FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
ELECTRONIC DEVICE
MITSUBISHI ELECTRIC CORPORATION, A CORPORATION ORGANISED AND
EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3,
MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO 1008310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
2
DESCRIPTION
Technical Field
[0001] The present disclosure relates to an electronic device.
Background Art
[0002] An electronic device, such as a power converter, installed on a railway vehicle5
dissipates, through a cooler, heat generated by electronic components into, for example,
passing air created by the traveling vehicle or cooling air supplied from a fan to cool the
electronic components. An example of such an electronic device is described in Patent
Literature 1. Patent Literature 1 describes a power converter attached to the roof of a
railway vehicle. The power converter includes fins attached to the upper surface and the10
side surfaces of a housing. The power converter described in Patent Literature 1
dissipates heat through heat transfer from the fins into air flowing along the fins and thermal
radiation from the fins to cool electronic components including semiconductor devices
accommodated in the housing of the power converter.
Citation List15
Patent Literature
[0003] Patent Literature 1: Unexamined Japanese Patent Application Publication
No. 2009-124038
Summary of Invention
Technical Problem20
[0004] In sunny weather, the fins are exposed to sunlight that reduces thermal
radiation from the fins, lowering the cooling performance of the electronic device. An
electronic device including a cover for the fins has vents across the cover surface for airflow.
The fins are thus exposed, through the vents, to sunlight that reduces thermal radiation,
lowering the cooling performance of the electronic device.25
[0005] Under such circumstances, an objective of the present disclosure is to provide
an electronic device that can cool electronic components also in sunny weather.
3
Solution to Problem
[0006] To achieve the above objective, an electronic device according to an aspect
of the present disclosure is installable on a roof of a vehicle. The electric device includes
a heat-receiving block being heat conductive, a heat transfer member, a plurality of fins,
and a cover. The heat-receiving block has a first main surface to which an electronic5
component is attached. The heat transfer member is attached to the heat-receiving block.
The heat transfer member extends away from a second main surface of the heat-receiving
block located opposite to the first main surface of the heat-receiving block and facing
vertically upward. The heat transfer member transfers heat transferred from the electronic
component through the heat-receiving block away from the second main surface. The10
plurality of fins is attached to the heat transfer member and dissipate heat transferred from
the electronic component through the heat-receiving block and the heat transfer member
into ambient air. The plurality of fins is arranged in at least one of a width direction of
the vehicle or a travel direction of the vehicle with spaces between the plurality of fins.
The cover includes a side wall and a lid. The side wall extends in a direction surrounding15
a normal line to the second main surface. The lid is attached to the side wall with the heat
transfer member located between the lid and the heat-receiving block. The cover
accommodates the heat transfer member and the plurality of fins in a space surrounded by
the side wall and the lid. The cover has a vent in at least an outer surface of the side wall
intersecting with the travel direction of the vehicle. A ratio of an open area of the vent on20
the side wall to an area of the outer surface of the side wall is higher than a ratio of an open
area of a vent on the lid to an area of an outer surface of the lid.
Advantageous Effects of Invention
[0007] The cover included in the electronic device according to the above aspect of
the present disclosure has the ratio of the open area of the vent to the area of the outer25
surface of the side wall that is higher than the ratio of the open area of the vent to the area
of the outer surface of the lid. The cover can thus reduce the amount of exposure of the
4
fins to sunlight and lower the likelihood of reduced thermal radiation from the fins. Thus,
the electronic device can cool the electronic component also in sunny weather.
Brief Description of Drawings
[0008] FIG. 1 is a block diagram of an electronic device according to Embodiment
1;5
FIG. 2 is a diagram of the electronic device according to Embodiment 1, mounted
on a vehicle in an example manner;
FIG. 3 is a cross-sectional view of the electronic device according to Embodiment 1
taken along line III-III in FIG. 2 as viewed in the direction indicated by the arrows;
FIG. 4 is a cross-sectional view of the electronic device according to Embodiment 110
taken along line IV-IV in FIG. 3 as viewed in the direction indicated by the arrows;
FIG. 5 is an exploded perspective view of a cover in Embodiment 1;
FIG. 6 is a top view of the electronic device according to Embodiment 1;
FIG. 7 is a diagram of example first vents in a side wall of the cover in Embodiment
1;15
FIG. 8 is a diagram of example second vents in a lid of the cover in Embodiment 1;
FIG. 9 is a diagram illustrating example passing air through the electronic device
according to Embodiment 1;
FIG. 10 is a diagram illustrating an example natural convection flow through the
electronic device according to Embodiment 1;20
FIG. 11 is a diagram illustrating an example natural convection flow through the
electronic device according to Embodiment 1;
FIG. 12 is a cross-sectional view of an electronic device according to Embodiment
2;
FIG. 13 is a top view of the electronic device according to Embodiment 2;25
FIG. 14 is a diagram of example second vents in a lid of a cover in Embodiment 2;
FIG. 15 is a cross-sectional view of an electronic device according to Embodiment
5
3;
FIG. 16 is a cross-sectional view of the electronic device according to Embodiment
3 taken along line XVI-XVI in FIG. 15 as viewed in the direction indicated by the arrows;
FIG. 17 is a perspective view of a cover in Embodiment 3;
FIG. 18 is a diagram illustrating an example natural convection flow through the5
electronic device according to Embodiment 3;
FIG. 19 is a cross-sectional view of an electronic device according to Embodiment
4;
FIG. 20 is a perspective view of a cover in Embodiment 4;
FIG. 21 is a top view of the electronic device according to Embodiment 4;10
FIG. 22 is a diagram illustrating an example natural convection flow through the
electronic device according to Embodiment 4;
FIG. 23 is a cross-sectional view of an electronic device according to Embodiment
5;
FIG. 24 is a perspective view of a cover in Embodiment 5;15
FIG. 25 is a top view of the electronic device according to Embodiment 5;
FIG. 26 is a diagram illustrating an example natural convection flow through the
electronic device according to Embodiment 5;
FIG. 27 is a cross-sectional view of an electronic device according to Embodiment
6;20
FIG. 28 is a cross-sectional view of the electronic device according to Embodiment
6 taken along line XXVIII-XXVIII in FIG. 27 as viewed in the direction indicated by the
arrows;
FIG. 29 is a diagram illustrating an example natural convection flow through the
electronic device according to Embodiment 6;25
FIG. 30 is a diagram illustrating an example natural convection flow through the
electronic device according to Embodiment 6;
6
FIG. 31 is a diagram of an electronic device according to a modification of an
embodiment; and
FIG. 32 is a diagram of the electronic device the embodiment, mounted on a vehicle
in another example manner.
Description of Embodiments5
[0009] An electronic device according to one or more embodiments of the present
disclosure is described in detail with reference to the drawings. Components identical or
corresponding to each other are provided with the same reference sign in the drawings.
[0010] Embodiment 1
One example of an electronic device is a power converter installable on a railway10
vehicle to convert alternating current (AC) power supplied from an AC power supply to
AC power to be supplied to a load and to supply the resulting AC power to the load. An
electronic device 1 according to an embodiment is described using, as an example, a power
converter installed on the roof of a railway vehicle to cool electronic components through
natural convection and passing air that is an airflow caused by a traveling railway vehicle15
and flowing in a direction opposite to the travel direction of the railway vehicle.
[0011] The electronic device 1 illustrated in FIG. 1 is installed on an AC feeding
railway vehicle. The electronic device 1 converts supplied AC power to AC power
appropriate for a motor 61 and an air-conditioner 62 serving as example loads, and supplies
the resulting AC power to the motor 61 and the air-conditioner 62. The motor 61 is, for20
example, a three-phase induction motor that generates propulsion of the railway vehicle.
When the electronic device 1 supplies power to the motor 61 during traveling of the railway
vehicle, more specifically, during power running, the motor 61 generates propulsion of the
railway vehicle. The air-conditioner 62 is an air conditioner in the railway vehicle.
When the electronic device 1 supplies power to the air-conditioner 62 during the operation25
of the railway vehicle, more specifically, during traveling or stopping of the railway vehicle,
the air-conditioner 62 operates to adjust the temperature in the railway vehicle to an
7
intended temperature.
[0012] The components of the electronic device 1 are described below. The
electronic device 1 includes a terminal 1a connected to the power supply and a terminal 1b
grounded. The electronic device 1 further includes a transformer 11 that lowers the
voltage of AC power supplied from the power supply connected to the terminal 1a, a5
converter 12 that converts the AC power having the voltage lowered by the transformer 11
to direct current (DC) power, a capacitor C1 charged with the DC power output from the
converter 12, and inverters 13 and 14 that convert the DC power input through the capacitor
C1 to AC power.
[0013] The terminal 1a is electrically connected to, for example, a current collector10
that acquires AC power supplied from an electrical substation through a power line. The
current collector serves as the power supply that supplies power to the electronic device 1.
The power line is, for example, an overhead power line or a third rail. The current
collector is a pantograph or a current collector shoe. The terminal 1b is short-circuited to
rails through, for example, a ground brush, a ground ring, or wheels, which are not15
illustrated, and grounded.
[0014] The transformer 11 includes a primary winding having one end connected to
the terminal 1a and the other end connected to the terminal 1b, and a secondary winding
connected to the converter 12. For example, the transformer 11 lowers single-phase AC
power with a voltage of 25 kV supplied from the current collector to single-phase AC20
power with a voltage of 1520 V, and supplies the AC power with the lowered voltage to
the converter 12.
[0015] The converter 12 includes two pairs of two switching elements SW1 that are
connected in series. The switching elements SW1 in one pair and the switching elements
SW1 in the other pair are connected in parallel. One end of the secondary winding in the25
transformer 11 is connected to the connection point of the two switching elements SW1 in
one pair, and the other end of the secondary winding of the transformer 11 is connected to
8
the connection point of the two switching elements SW1 in the other pair.
[0016] Each switching element SW1 includes an insulated-gate bipolar transistor
(IGBT) and a freewheeling diode having an anode connected to the emitter terminal of the
IGBT and a cathode connected to the collector terminal of the IGBT. A non-illustrated
controller provides a gate signal to the gate terminal of the IGBT included in each switching5
element SW1 included in the converter 12 to turn on or off the IGBT, or in other words, to
turn on or off the switching element SW1. Each switching element SW1 performs
switching to cause the converter 12 to convert AC power supplied from the transformer 11
to DC power.
[0017] The capacitor C1 is charged with DC power output from the converter 12.10
The capacitor C1 has one end connected to the connection point between the positive
terminal of the converter 12 and the primary positive terminals of the inverters 13 and 14
and the other end connected to the connection point between the negative terminal of the
converter 12 and the primary negative terminals of the inverters 13 and 14.
[0018] The inverter 13 includes three pairs of two switching elements SW2 that are15
connected in series. The three pairs of switching elements SW2 correspond to the U
phase, the V phase, and the W phase of three-phase AC power. The switching elements
SW2 corresponding to the U phase, the switching elements SW2 corresponding to the V
phase, and the switching elements SW2 corresponding to the W phase are connected
parallel to one another between the primary positive terminal and the primary negative20
terminal of the inverter 13. The connection point of the two switching elements SW2
corresponding to the U phase, the connection point of the two switching elements SW2
corresponding to the V phase, and the connection point of the two switching elements SW2
corresponding to the W phase are connected to the motor 61.
[0019] Similarly to the switching elements SW1, each switching element SW225
includes an IGBT and a freewheeling diode. The non-illustrated controller provides a
gate signal to the gate terminal of the IGBT included in each switching element SW2
9
included in the inverter 13 to turn on or off the IGBT, or in other words, to turn on or off
the switching element SW2. Each switching element SW2 performs switching to cause
the inverter 13 to convert DC power to three-phase AC power and supply the three-phase
AC power to the motor 61.
[0020] The inverter 14 includes three pairs of two switching elements SW3 that are5
connected in series. The three pairs of switching elements SW3 correspond to the U
phase, the V phase, and the W phase of three-phase AC power. The switching elements
SW3 corresponding to the U phase, the switching elements SW3 corresponding to the V
phase, and the switching elements SW3 corresponding to the W phase are connected
parallel to one another between the primary positive terminal and the primary negative10
terminal of the inverter 14.
[0021] Similarly to the switching elements SW1, each switching element SW3
includes an IGBT and a freewheeling diode. The non-illustrated controller provides a
gate signal to the gate terminal of the IGBT included in each switching element SW3
included in the inverter 14 to turn on or off the IGBT, or in other words, to turn on or off15
the switching element SW3. Each switching element SW3 performs switching to cause
the inverter 14 to convert DC power to three-phase AC power.
[0022] The inverter 14 further includes a transformer 15 that lowers the voltage of
the three-phase AC power converted from DC power to a voltage appropriate for the air-
conditioner 62. The connection point of the two switching elements SW3 corresponding20
to the U phase, the connection point of the two switching elements SW3 corresponding to
the V phase, and the connection point of the two switching elements SW3 corresponding
to the W phase are connected to the transformer 15. The three-phase AC power with the
voltage lowered by the transformer 15 is supplied to the air-conditioner 62.
[0023] When the railway vehicle is traveling, the converter 12 and the inverters 1325
and 14 are in operation. Thus, the switching elements SW1, SW2, and SW3 are
repeatedly turned on and off, more specifically, perform switching and generate heat.
10
When the railway vehicle is stopped, the motor 61 receives no power, but the air-
conditioner 62 is to operate although the railway vehicle is stopped. Thus, when the
railway vehicle is stopped, the inverter 13 is stopped, and the converter 12 and the inverter
14 are in operation. In other words, the switching elements SW2 generate no heat,
whereas the switching elements SW1 and SW3 are repeatedly turned on and off and5
generate heat.
[0024] The electronic device 1 thus includes a structure that cools electronic
components including the switching elements SW1, SW2, and SW3 with passing air when
the railway vehicle is traveling and cools electronic components including the switching
elements SW1 and SW3 through natural convection when the railway vehicle is stopped.10
The electronic device 1 further includes a structure that lowers the likelihood of reduced
radiation from the fins resulting from exposure to sunlight in sunny weather both when the
railway vehicle is traveling and when the railway vehicle is stopped.
[0025] The structure of the electronic device 1 is described in detail below. As
illustrated in FIG. 2, the electronic device 1 is installed on a roof 100a of a vehicle 100.15
As illustrated in FIG. 3 that is a cross-sectional view taken along line III-III in FIG. 2 as
viewed in the direction indicated by the arrows, the electronic device 1 includes a heat
conductive heat-receiving block 21 having a first main surface 21a to which the electronic
components are attached, and heat transfer members 22 attached to a second main surface
21b of the heat-receiving block 21 facing vertically upward, more specifically, in the20
positive Z-direction, to transfer heat transferred from the electronic components through
the heat-receiving block 21 away from the second main surface 21b. The electronic
device 1 further includes multiple fins 23 attached to the heat transfer members 22. The
fins 23 dissipate heat transferred from the electronic components through the heat-
receiving block 21 and the heat transfer members 22 into ambient air.25
[0026] Preferably, the electronic device 1 further include a housing 20 installed on
the roof 100a and accommodating electronic components including the switching elements
11
SW1, SW2, and SW3. In this case, the heat-receiving block 21 may be attached to the
housing 20 to close an opening 20a of the housing 20. To suppress breakage of the heat
transfer members 22 and the fins 23, the electronic device 1 includes a cover 30 attached
to the housing 20 to cover the heat transfer members 22 and the fins 23.
[0027] In FIGS. 2 and 3, Z-axis indicates a vertical direction for the vehicle 1005
located horizontally. X-axis indicates a travel direction of the vehicle 100. Y-axis
indicates a width direction of the vehicle 100. X-axis, Y-axis, and Z-axis are
perpendicular to one another. The same applies to the subsequent figures.
[0028] The housing 20 is attached to a vertically upper portion of the roof 100a.
The housing 20 is rigid and strong enough to resist deformation under the maximum10
expected vibration from the railway vehicle. For example, the housing 20 is formed of
metal such as iron or aluminum. The housing 20 has the opening 20a in a vertically upper
portion.
[0029] The heat-receiving block 21 is attached to the housing 20 to close the opening
20a. In the embodiment, the heat-receiving block 21 is a plate formed of a highly15
thermally conductive material including metal such as iron or aluminum, and is attached
to the outer surface of the housing 20 to close the opening 20a. Electronic components
that generate heat, more specifically, the switching elements SW1, SW2, and SW3, are
attached to the first main surface 21a of the heat-receiving block 21. The heat transfer
members 22 are attached to the second main surface 21b opposite to the first main surface20
21a and facing vertically upward. For the vehicle 100 located horizontally, the first main
surface 21a and the second main surface 21b extend horizontally.
[0030] Each heat transfer member 22 extends away from the second main surface
21b and transfers heat transferred from the electronic components through the heat-
receiving block 21 away from the second main surface 21b. In the embodiment, each25
heat transfer member 22 includes a heat pipe that contains a coolant. More specifically,
each heat transfer member 22 serving as a heat pipe includes a header 24 attached to the
12
heat-receiving block 21 and a branch pipe 25 attached to the header 24 and continuous with
the header 24. The header 24 and the branch pipe 25 contain a coolant in vapor and liquid
phases at ambient temperature. An example of the coolant is water. In Embodiment 1,
the headers 24 and the branch pipes 25 are symmetrically arranged with respect to an XZ
plane.5
[0031] As illustrated in FIG. 3 and FIG. 4 that is a cross-sectional view taken along
line IV-IV in FIG. 3 as viewed in the direction indicated by the arrows, multiple headers
24 extending in X-direction are arranged in Y-direction. Each header 24 is received in a
groove on the second main surface 21b of the heat-receiving block 21, and attached to the
heat-receiving block 21 by, for example, bonding with an adhesive, welding, brazing, or10
soldering. Each header 24 is a pipe formed of a highly thermally conductive material
including metal such as iron or aluminum. Multiple branch pipes 25 are attached to each
header 24.
[0032] When the vehicle 100 is traveling, passing air heated with heat transferred
from the fins 23 at the front in the travel direction of the vehicle 100 flows rearward in the15
travel direction of the vehicle 100. Thus, the electronic device 1 may cool the electronic
components located at the rear in the travel direction of the vehicle 100 less effectively than
the electronic components located at the front in the travel direction of the vehicle 100.
As described above, the headers 24 extending in X-direction and convection of the coolant
in the headers 24 facilitate dispersion of heat in X-direction, and reduce nonuniform20
cooling of the electronic components arranged in X-direction.
[0033] Each branch pipe 25 extends away from the heat-receiving block 21, for
example, in the positive Z-direction. Each branch pipe 25 is attached to the corresponding
header 24 by, for example, welding, brazing, or soldering and continuous with the header
24. Each branch pipe 25 is formed of a highly thermally conductive material including25
metal such as iron or aluminum.
[0034] Each branch pipe 25 has a length below a vehicle limit in the cross section
13
taken perpendicularly to the travel direction of the vehicle 100, more specifically, a YZ
plane. The vehicle limit indicates a maximum dimension of the vehicle 100. In
Embodiment 1, the branch pipes 25 have different lengths corresponding to the vehicle
limit. More specifically, as illustrated in FIG. 3, the length of the branch pipes 25 in Z-
direction attached to the two headers 24 at both the ends in Y-direction is shorter than the5
length of the branch pipes 25 in Z-direction attached to the four headers 24 in the middle
in Y-direction.
[0035] The fins 23 are arranged in at least the width direction or the travel direction
of the vehicle 100 with spaces between the fins 23. In Embodiment 1, the fins 23 are
arranged in the width direction of the vehicle 100, or in other words, in Y-direction, with10
spaces between the fins 23. The fins 23 are further arranged in the direction away from
the heat-receiving block 21, or in other words, in Z-direction, with spaces between the fins
23.
[0036] The fins 23 arranged in the above manner are attached to the heat transfer
members 22. More specifically, the fins 23 are attached to the heat transfer members 2215
to receive the heat transfer members 22 in through-holes in the fins 23. The fins 23
attached to the heat transfer members 22 dissipate heat transferred from the electronic
components through the heat-receiving block 21 and the heat transfer members 22 into
ambient air. In Embodiment 1, the fins 23 are plates of a highly thermally conductive
material including metal such as iron or aluminum.20
[0037] To enhance the cooling performance for the electronic components when the
vehicle 100 is traveling, the main surfaces of the fins 23 may be parallel to X-axis. The
passing air created by the traveling vehicle 100 flows in X-direction. Thus, the fins 23
having the main surfaces parallel to X-axis can efficiently transfer heat from the fins 23 to
passing air flowing between the fins 23. This structure can cool the electronic25
components including the switching elements SW1, SW2, and SW3.
[0038] In Embodiment 1, the fins 23 are attached to the heat transfer members 22,
14
more specifically, to the branch pipes 25, with the main surfaces extending substantially
horizontally for the vehicle 100 located horizontally. The main surfaces extending
substantially horizontally refer to the main surfaces that form a sufficiently small angle
with the horizontal plane, for example, lower than or equal to 10 degrees.
[0039] The cover 30 is attached to the housing 20 to cover the heat-receiving block5
21, the heat transfer members 22, and the fins 23. The cover 30 is rigid and strong enough
to resist deformation under the maximum expected vibration from the railway vehicle.
For example, the cover 30 is formed of metal such as iron or aluminum. The cover 30 is
attached to the housing 20 by, for example, fastening with fasteners, welding, or brazing.
[0040] As illustrated in FIGS. 5 and 6, the cover 30 includes a side wall 31 extending10
in a direction surrounding the normal line to the second main surface 21b, and a lid 32
attached to the side wall 31 with the heat transfer members 22 located between the lid 32
and the heat-receiving block 21. The normal line to the second main surface 21b is
parallel to Z-axis. The side wall 31 thus has a tubular shape extending about Z-axis. The
lid 32 is attached to the side wall 31 in an orientation to close an opening at one end of the15
side wall 31.
[0041] The cover 30 accommodates the heat-receiving block 21, the heat transfer
members 22, and the fins 23 in the space surrounded by the side wall 31 and the lid 32.
The cover 30 has through-holes serving as vents in at least the outer surfaces of the side
wall 31 intersecting with the travel direction of the vehicle, or in other words, X-direction.20
The ratio of the open areas of the vents to the areas of the outer surfaces of the side wall 31
is higher than the ratio of the open areas of the vents to the areas of the outer surfaces of
the lid 32.
[0042] In Embodiment 1, the vents include first vents 31a that are through-holes in
the side wall 31 and second vents 32a that are through-holes in the lid 32. More25
specifically, the first vents 31a are located in the outer surfaces of the side wall 31, and the
second vents 32a are located in the outer surfaces of the lid 32. In this case, the ratio of
15
the open areas of the vents to the areas of the outer surfaces of the side wall 31 is the ratio
of the sum of the open areas of the first vents 31a in the outer surfaces of the side wall 31
to the sum of the areas of the outer surfaces of the side wall 31. The ratio of the open
areas of the vents to the areas of the outer surfaces of the lid 32 is the ratio of the sum of
the open areas of the second vents 32a in the outer surfaces of the lid 32 to the sum of the5
areas of the outer surfaces of the lid 32.
[0043] The first vents 31a in the surfaces of the side wall 31 have the same shape.
As illustrated in FIG. 7 that is an enlarged view of an outer surface of the side wall 31
intersecting with X-axis as viewed in the negative X-direction, each first vent 31a is
substantially square, with a length d1 on each side. In the outer surfaces of the side wall10
31 intersecting with X-axis, the first vents 31a are arranged at intervals g1 in Z-direction
and Y-direction. Although not illustrated, in the outer surfaces of the side wall 31
intersecting with Y-axis, the first vents 31a are arranged at intervals g1 in Z-direction and
X-direction.
[0044] As illustrated in FIGS. 5 and 6, the second vents 32a in the outer surfaces of15
the lid 32 have the same shape. As illustrated in FIG. 8 that is an enlarged view of the
outer surface of the lid 32 perpendicular to Z-axis as viewed in the negative Z-direction,
each second vent 32a is substantially square, with a length d2 on each side. The second
vents 32a are arranged at intervals g1 in X-direction and a direction perpendicular to X-
axis in the outer surface of the lid 32. In the outer surfaces of the lid 32 perpendicular to20
Z-axis, the second vents 32a are arranged at intervals g1 in X-direction and Y-direction.
[0045] As described above, the intervals g1 between the first vents 31a are the same
as the intervals g1 between the second vents 32a, and the length d2 of each side of the
second vents 32a is shorter than the length d1 of each side of the first vents 31a. Thus,
the ratio of the open areas of the first vents 31a to the areas of the outer surfaces of the side25
wall 31 is higher than the ratio of the open areas of the second vents 32a to the areas of the
outer surfaces of the lid 32. The electronic device 1 can thus lower the likelihood of
16
reduced thermal radiation from the fins 23 resulting from sunlight exposure more
effectively than an electronic device having many vents, such as the first vents 31a, located
uniformly across the full portion of the cover. For example, the ratio of the open areas of
the first vents 31a to the areas of the outer surfaces of the side wall 31 is preferably higher
than or equal to 0.7, and the ratio of the open areas of the second vents 32a to the areas of5
the outer surfaces of the lid 32 is preferably lower than or equal to 0.6.
[0046] Cooling of the electronic components of the electronic device 1 with the
above structure is described below. Heat generated by at least one of the switching
elements SW1, SW2, and SW3 is transferred to the coolant through the heat-receiving
block 21 and the headers 24. This evaporates the coolant. The evaporated coolant flows10
into the branch pipes 25 from the headers 24 and moves in the branch pipes 25 in the
positive Z-direction. While moving in the positive Z-direction, the coolant transfers heat
to air around the heat transfer members 22 through the branch pipes 25 and the fins 23.
The coolant then cools and liquefies. The liquid coolant moves in the negative Z-
direction along the inner walls of the branch pipes 25. As described above, the coolant15
circulates while repeating evaporation and liquefaction to transfer heat generated by at least
any of the switching elements SW1, SW2, and SW3 to air around the heat transfer
members 22 and cool the switching elements SW1, SW2, and SW3 generating heat.
[0047] For example, when the vehicle 100 travels in the positive X-direction, passing
air flows in the negative X-direction as indicated by the arrow AR1 in FIG. 9. For20
simplicity, FIG. 9 illustrates a portion of the airflow. The passing air flows between the
fins 23. The passing air flowing between the fins 23 receives heat transferred from the
fins 23 and cools the switching elements SW1, SW2, and SW3.
[0048] When the vehicle 100 is stopped, no passing air flows unlike in FIG. 9. Air
heated with heat transferred from the fins 23 or the branch pipes 25 moves vertically25
upward through the spaces between the fins 23 as indicated by the arrows AR2 in FIGS.
10 and 11. For simplicity, FIGS. 10 and 11 simply illustrate a portion of airflow. Air
17
moving vertically upward flows out of the cover 30 through the second vents 32a in the lid
32 of the cover 30
[0049] As the air inside the cover 30 flows out through the second vents 32a, air
outside the cover 30 flows into the cover 30 through the first vents 31a in the side wall 31
of the cover 30 as indicated by the arrows AR3 in FIGS. 10 and 11.5
[0050] The air flowing into the cover 30 as indicated by the arrows AR3 receives
heat transferred from the fins 23 to be heated and moves vertically upward through the
spaces between the fins 23 as indicated by the arrows AR2, flowing out of the cover 30
through the second vents 32a. The switching elements SW1, SW2, and SW3 can thus be
cooled also when the vehicle 100 is stopped through such natural convection.10
[0051] Both when the vehicle 100 is traveling and when the vehicle 100 is stopped,
thermal radiation from the fins 23 located at the vertically upper end transfers heat to the
inner surfaces of the lid 32 to cool the switching elements SW1, SW2, and SW3.
[0052] As described above, the cover 30 included in the electronic device 1 according
to Embodiment 1 has the ratio of the open areas of the first vents 31a to the areas of the15
outer surfaces of the side wall 31 higher than the ratio of the open areas of the second vents
32a to the areas of the outer surfaces of the lid 32. In other words, the ratio of the open
areas of the second vents 32a to the areas of the outer surfaces of the lid 32 is lower than
the ratio of the open areas of the first vents 31a to the areas of the outer surfaces of the side
wall 31. The electronic device 1 thus lowers the likelihood of reduced thermal radiation20
from the fins 23 resulting from exposure to sunlight more effectively than an electronic
device having many vents, such as the first vents 31a, located uniformly across the full
portion of the cover. Thus, the electronic device 1 can cool the electronic components
also in sunny weather.
[0053] The ratio of the open areas of the first vents 31a to the areas of the outer25
surfaces of the side wall 31 intersecting with the travel direction, or in other words, X-
direction, is higher than the ratio of the open areas of the second vents 32a to the areas of
18
the outer surfaces of the lid 32. This structure can lower the likelihood of reduced thermal
radiation from the fins 23 resulting from exposure to sunlight, when the vehicle 100 is
traveling, this structure can effectively cool the switching elements SW1, SW2, and SW3
with passing air created by the vehicle 100.
[0054] The lid 32 having the second vents 32a smaller than the first vents 31a can5
lower the likelihood of reduced thermal radiation from the fins 23 resulting from exposure
to sunlight and allow, when the vehicle 100 is stopped, air heated with heat transferred
from the fins 23 to flow out of the cover 30 through the second vents 32a. Thus, the
switching elements SW1, SW2, and SW3 can be cooled through natural convection when
the vehicle 100 is stopped.10
[0055] Embodiment 2
The cover 30 may have any shape other than the shape in the above example to lower
the likelihood of reduced thermal radiation from the fins 23 resulting from exposure to
sunlight. An electronic device 2 according to Embodiment 2 includes a cover 30 having
a shape different from the shape of the cover 30 in Embodiment 1, and is described focusing15
on the differences from the electronic device 1.
[0056] The cover 30 included in the electronic device 2 illustrated in FIG. 12 includes
the side wall 31 and a lid 33 attached to the side wall 31 with the heat transfer members 22
located between the lid 33 and the heat-receiving block 21. The cover 30 accommodates
the heat-receiving block 21, the heat transfer members 22, and the fins 23 in the space20
surrounded by the side wall 31 and the lid 33. The cover 30 has vents in at least the
surfaces of the side wall 31 intersecting with X-direction. The ratio of the open areas of
the vents to the areas of the outer surfaces of the side wall 31 is higher than the ratio of the
open areas of the vents to the areas of the outer surfaces of the lid 33.
[0057] In Embodiment 2, as in Embodiment 1, the vents include first vents 31a in the25
outer surfaces of the side wall 31 and second vents 33a in the outer surfaces of the lid 33.
In this case, as in Embodiment 1, the ratio of the open areas of the vents to the areas of the
19
outer surfaces of the side wall 31 is the ratio of the sum of the open areas of the first vents
31a in the outer surfaces of the side wall 31 to the sum of the areas of the outer surfaces of
the side wall 31. The ratio of the open areas of the vents to the areas of the outer surfaces
of the lid 33 is the ratio of the sum of the open areas of the second vents 33a in the outer
surfaces of the lid 33 to the sum of the areas of the outer surfaces of the lid 33. The5
intervals between the second vents 33a in the lid 33 are wider than the intervals between
the second vents 32a in the lid 32 illustrated in FIG. 3.
[0058] As illustrated in FIG. 13, the second vents 33a in the outer surfaces of the lid
33 have the same shape. As illustrated in FIG. 14 that is an enlarged view of the surface
of the lid 33 perpendicular to Z-axis as viewed in the negative Z-direction, each second10
vent 33a is substantially square, with a length d2 on each side as in the second vents 32a in
Embodiment 1. The second vents 33a are arranged at wider intervals than the second
vents 32a in Embodiment 1.
[0059] More specifically, the second vents 33a are arranged in the outer surfaces of
the lid 33 at intervals g2 = g1 + d2 + g1 in X-direction and in a direction perpendicular to15
X-axis. In the outer surfaces of the lid 33 perpendicular to Z-axis, the second vents 33a
are arranged at the intervals g2 in X-direction and Y-direction. Thus, the second vents
33a are fewer than the second vents 32a in the lid 32 of the cover 30 included in the
electronic device 1 according to Embodiment 1.
[0060] As described above, the intervals g1 between the first vents 31a are shorter20
than the intervals g2 between the second vents 33a, and the length d2 of each side of the
second vents 32a is shorter than the length d1 of each side of the first vents 31a. Thus,
the ratio of the open areas of the first vents 31a to the areas of the outer surfaces of the side
wall 31 is higher than the ratio of the open areas of the second vents 33a to the areas of the
outer surfaces of the lid 33.25
[0061] The electronic device 2 with the above structure cools the electronic
components with the same mechanism as in Embodiment 1.
20
[0062] As described above, the cover 30 included in the electronic device 2 according
to Embodiment 2 has the ratio of the open areas of the second vents 33a to the areas of the
outer surfaces of the lid 33 lower than the ratio of the open areas of the first vents 31a to
the areas of the outer surfaces of the side wall 31. The ratio of the open areas of the second
vents 33a to the areas of the outer surfaces of the lid 33 is lower than in Embodiment 1.5
The structure can further lower the likelihood of reduced thermal radiation from the fins 23
resulting from exposure to sunlight. Thus, the electronic device 2 has higher cooling
performance for the electronic components in sunny weather.
[0063] Embodiment 3
The fins and the cover 30 may have any shapes other than in the above examples.10
An electronic device 3 according to Embodiment 3 includes fins and a cover 30 with shapes
different from the shapes of the fins and the cover 30 in Embodiments 1 and 2, and is
described focusing on the differences from Embodiments 1 and 2.
[0064] The electronic device 3 illustrated in FIGS. 15 and 16 includes multiple fins
26 arranged in X-direction, Y-direction, and Z-direction with spaces between the fins 26.15
For the vehicle 100 located horizontally, the fins 26 are attached to the heat transfer
members 22, or in other words, the branch pipes 25, with the main surfaces extending
substantially horizontally.
[0065] The cover 30 included in the electronic device 3 includes the side wall 31 and
a lid 34 attached to the side wall 31 with the heat transfer members 22 located between the20
lid 34 and the heat-receiving block 21. The cover 30 accommodates the heat-receiving
block 21, the heat transfer members 22, and the fins 26 in the space surrounded by the side
wall 31 and the lid 34.
[0066] The cover 30 has vents in at least the outer surfaces of the side wall 31
intersecting with X-direction. In Embodiment 3, the side wall 31 has the first vents 31a25
in each of the outer surfaces. The first vents 31a in the outer surfaces of the side wall 31
have the same shape and are at the same intervals as in Embodiment 1.
21
[0067] As illustrated in FIGS. 15, 16, and 17, the lid 34 has no vents, and thus the
ratio of the open areas of the vents to the areas of the outer surfaces of the lid 34 is zero.
In other words, in Embodiment 3, the side wall 31 alone has vents, more specifically, the
first vents 31a. The ratio of the open areas of the vents to the areas of the outer surfaces
of the side wall 31 is thus higher than the ratio of the open areas of the vents to the areas of5
the outer surfaces of the lid 34.
[0068] Cooling of the electronic components of the electronic device 3 with the
above structure is described below. When the vehicle 100 is traveling, as in Embodiment
1, passing air receives heat from the fins 26 and cools the electronic components, more
specifically, the switching elements SW1, SW2, and SW3.10
[0069] When the vehicle 100 is stopped, no passing air occurs. Air heated with heat
transferred from the fins 26 or the branch pipes 25 moves vertically upward through the
spaces between the fins 26, as indicated by the arrows AR4 in FIG. 18. The lid 34 of the
cover 30 has no vents. Thus, the air that has moved in the positive Z-direction moves
along the lid 34 of the cover 30, and flows out of the cover 30 through the first vents 31a.15
For simplicity, FIG. 18 illustrates a portion of the airflow. Although not illustrated in FIG.
18, a portion of the air that have moved vertically upward flows out of the cover 30 through
the first vents 31a in the surfaces of the side wall 31 intersecting with Y-direction.
[0070] When air inside the cover 30 flows out through the first vents 31a, as in
Embodiment 1, air outside the cover 30 flows into the cover 30 through the first vents 31a20
in the side wall 31 of the cover 30 as indicated by the arrows AR3. Although not
illustrated in FIG. 18, as in Embodiment 1, air outside the cover 30 also flows into the cover
30 through the first vents 31a in the surfaces of the side wall 31 intersecting with Y-
direction.
[0071] The air flowing into the cover 30 receives heat transferred from the fins 2625
and the branch pipes 25 to be heated, moves vertically upward through the spaces between
the fins 26 as described above, and flows along the lid 34 and out of the cover 30 through
22
the first vents 31a. The switching elements SW1, SW2, and SW3 can thus be cooled
through such natural convection also when the vehicle 100 is stopped.
[0072] Both when the vehicle 100 is traveling and when the vehicle 100 is stopped,
heat is transferred to the inner surfaces of the lid 34 by thermal radiation from the fins 26
located at the vertical upper end to cool the switching elements SW1, SW2, and SW3.5
[0073] As described above, the lid 34 of the cover 30 included in the electronic device
3 according to Embodiment 3 has no vents. This structure lowers the likelihood of
reduced thermal radiation from the fins 26 resulting from exposure to sunlight. Thus, the
electronic device 3 has higher cooling performance for the electronic components in sunny
weather.10
[0074] Embodiment 4
The fins and the cover 30 may have any shapes other than in the above examples.
An electronic device 4 according to Embodiment 4 includes fins and a cover 30 with shapes
different from the shapes of the fins and the cover 30 in Embodiments 1 to 3, and is
described focusing on the differences from Embodiments 1 to 3.15
[0075] The electronic device 4 illustrated in FIG. 19 includes multiple fins 27
attached to the heat transfer members 22 with the main surfaces inclined with respect to
the second main surface 21b. In other words, the multiple fins 27 are attached to the
branch pipes 25 of the heat transfer members 22 with the main surfaces inclined with
respect to the horizontal plane for the vehicle 100 located horizontally. More specifically,20
the fins 27 are attached to the branch pipes 25 with the main surfaces inclined with respect
to the second main surface 21b and parallel to X-axis.
[0076] The cover 30 included in the electronic device 4 includes the side wall 31 and
a lid 35 attached to the side wall 31 with the heat transfer members 22 located between the
lid 35 and the heat-receiving block 21. The cover 30 accommodates the heat-receiving25
block 21, the heat transfer members 22, and the fins 27 in the space surrounded by the side
wall 31 and the lid 35.
23
[0077] The cover 30 has vents in at least the outer surfaces of the side wall 31
intersecting with X-direction. The ratio of the open areas of the vents to the areas of the
outer surfaces of the side wall 31 is higher than the ratio of the open areas of the vents to
the areas of the outer surfaces of the lid 35.
[0078] In Embodiment 4, as in Embodiment 1, the vents include first vents 31a in the5
outer surfaces of the side wall 31 and second vents 35a in the outer surfaces of the lid 35.
In this case, as in Embodiment 1, the ratio of the open areas of the vents to the areas of the
outer surfaces of the side wall 31 is the ratio of the sum of the open areas of the first vents
31a in the outer surfaces of the side wall 31 to the sum of the areas of the outer surfaces of
the side wall 31. The ratio of the open areas of the vents to the areas of the outer surfaces10
of the lid 35 is the ratio of the sum of the open areas of the second vents 35a in the outer
surfaces of the lid 35 to the sum of the areas of the outer surfaces of the lid 35.
[0079] As illustrated in FIGS. 19 to 21, the outer surfaces of the lid 35 has the second
vents 35a at or near the positions to face the second main surface 21b across the spaces
between the fins 27. In other words, the second vents 35a are located to allow air moving15
vertically upward through the spaces between the fins 27 to flow out of the cover 30. The
second vents 35a in the surfaces of the lid 35 have the same shape. For example, the
second vents 35a have the same shape as the second vents 32a in the lid 32 of the cover 30
included in the electronic device 1 according to Embodiment 1, and are at the same
intervals as the second vents 32a at the positions to face the second main surface 21b across20
the spaces between the fins 27.
[0080] Although the second vents 35a have the same shape as the second vents 32a
and are at the same intervals from one another as the second vents 32a, the second vents
35a are located to allow air moving vertically upward through the spaces between the fins
27 to flow out of the cover 30. In other words, the lid 35 has no second vents 35a at25
positions in the lid 35 other than the above positions, for example, at positions in the lid 35
facing the middle portions of the fins 27 in Y-direction. Thus, the second vents 35a are
24
fewer than the second vents 32a in the lid 32 of the cover 30 included in the electronic
device 1 according to Embodiment 1.
[0081] Cooling of the electronic components of the electronic device 4 with the
above structure is described below. The fins 27 are attached to the heat transfer members
22 with the main surfaces extending along X-axis. When the vehicle 100 is traveling, as5
in Embodiment 1, passing air receives heat transferred from the fins 27 and cools the
electronic components, more specifically, the switching elements SW1, SW2, and SW3.
[0082] When the vehicle 100 is stopped, no passing air occurs. Air heated with heat
transferred from the fins 27 and the branch pipes 25 moves vertically upward along the
main surfaces of the fins 27, as indicated by the arrows AR5 in FIG. 22, and then moves10
vertically upward through the spaces between the fins 27 adjacent to one another in Y-
direction. The air that has moved vertically upward through the spaces between the fins
27 flows out of the cover 30 through the second vents 35a in the lid 35. For simplicity,
FIG. 22 illustrates a portion of the airflow.
[0083] When air inside the cover 30 flows out through the second vents 35a, as in15
Embodiment 1, air outside the cover 30 flows into the cover 30 through the first vents 31a
in the side wall 31 of the cover 30 as indicated by the arrows AR3. Although not
illustrated in FIG. 22, as in Embodiment 1, air outside the cover 30 also flows into the cover
30 through the first vents 31a in the surfaces of the side wall 31 intersecting with Y-
direction.20
[0084] The air flowing into the cover 30 receives heat transferred from the fins 27
and the branch pipes 25 to be heated, moves vertically upward along the fins 27 and then
vertically upward through the spaces between the fins 27, and flows out of the cover 30
through the second vents 35a as described above. The switching elements SW1, SW2,
and SW3 can thus be cooled through such natural convection also when the vehicle 100 is25
stopped.
[0085] Both when the vehicle 100 is traveling and when the vehicle 100 is stopped,
25
heat is transferred to the inner surfaces of the lid 35 by thermal radiation from the fins 27
located at the vertical upper end to cool the switching elements SW1, SW2, and SW3.
[0086] As described above, the ratio of the open areas of the second vents 35a to the
areas of the outer surfaces of the lid 35 of the cover 30 included in the electronic device 4
according to Embodiment 4 is lower than the ratio of the open areas of the first vents 31a5
to the areas of the outer surfaces of the side wall 31. The second vents 35a are located to
face the second main surface 21b across the spaces between the fins 27. The ratio of the
open areas of the second vents 35a to the areas of the outer surfaces of the lid 35 is lower
than in Embodiment 1. This structure can further lower the likelihood of reduced thermal
radiation from the fins 27 resulting from exposure to sunlight. Thus, the electronic device10
4 has higher cooling performance for the electronic components in sunny weather.
[0087] The fins 27 are attached to the branch pipes 25 of the heat transfer members
22 with the main surfaces inclined with respect to the horizontal plane for the vehicle 100
located horizontally. The second vents 35a in the lid 35 are located to face the second
main surface 21b across the spaces between the fins 27. Thus, the air heated with heat15
transferred from the fins 27 and the branch pipes 25 moves vertically upward along the fins
27, moves vertically upward through the spaces between the fins 27, and flows out of the
cover 30 through the second vents 35a in the lid 35. Air thus smoothly moves vertically
upward through natural cooling. This increases cooling performance through natural
cooling when the vehicle 100 is stopped.20
[0088] Embodiment 5
The fins and the cover 30 may have any shapes other than in the above examples.
An electronic device 5 according to Embodiment 5 includes fins and a cover 30 with shapes
different from the shapes of the fins and the cover 30 in Embodiments 1 to 4, and is
described focusing on the differences from Embodiments 1 to 4.25
[0089] The electronic device 5 illustrated in FIG. 23 includes multiple fins 28 having
through-holes 28a. The fins 28 are attached to the branch pipes 25 of the heat transfer
26
members 22 with the main surfaces substantially parallel to the second main surface 21b.
The fins 28 have the through-holes 28a extending through the fins 28 away from the second
main surface 21b.
[0090] The cover 30 included in the electronic device 5 includes the side wall 31 and
a lid 36 attached to the side wall 31 with the heat transfer members 22 located between the5
lid 36 and the heat-receiving block 21. The cover 30 accommodates the heat-receiving
block 21, the heat transfer members 22, and the fins 28 in the space surrounded by the side
wall 31 and the lid 36.
[0091] The cover 30 has vents in at least the outer surfaces of the side wall 31
intersecting with X-direction. The ratio of the open areas of the vents to the areas of the10
outer surfaces of the side wall 31 is higher than the ratio of the open areas of the vents to
the areas of the outer surfaces of the lid 36.
[0092] In Embodiment 5, as in Embodiment 1, the vents include first vents 31a in the
outer surfaces of the side wall 31 and second vents 36a in the outer surfaces of the lid 36.
In this case, as in Embodiment 1, the ratio of the open areas of the vents to the areas of the15
outer surfaces of the side wall 31 is the ratio of the sum of the open areas of the first vents
31a in the outer surfaces of the side wall 31 to the sum of the areas of the outer surfaces of
the side wall 31. The ratio of the open areas of the vents to the areas of the outer surfaces
of the lid 36 is the ratio of the sum of the open areas of the second vents 36a in the outer
surfaces of the lid 36 to the sum of the areas of the outer surfaces of the lid 36.20
[0093] As illustrated in FIGS. 23 to 25, as in Embodiment 5, the second vents 36a
are located in the outer surfaces of the lid 36 at or near the positions to face the second main
surface 21b across the spaces between the fins 28 and at or near the positions to face the
through-holes 28a in the fins 28. In other words, the second vents 36a are located to allow
air moving vertically upward through the spaces between the fins 28 and air moving25
vertically upward through the through-holes 28a in the fins 28 to flow out of the cover 30.
The second vents 36a in the surfaces of the lid 36 have the same shape. For example, the
27
second vents 36a have the same shape as the second vents 32a in the lid 32 of the cover 30
included in the electronic device 1 according to Embodiment 1, and are at the same
intervals as the second vents 32a at the positions to face the second main surface 21b across
the spaces between the fins 28 and at the positions to face the through-holes 28a in the fins
28.5
[0094] Although the second vents 36a have the same shape as the second vents 32a,
and the second vents 36a adjacent to one another are at the same intervals as the second
vents 32a, the second vents 36a are located to allow air moving vertically upward through
the spaces between the fins 28 and air moving vertically upward through the through-holes
28a in the fins 28 to flow out of the cover 30. In other words, the lid 36 has no second10
vents 35a at the positions other than the above positions, for example, at positions facing
the portions between the ends of the fins 28 and the through-holes 28a. Thus, the second
vents 36a are fewer than the second vents 32a in the lid 32 of the cover 30 included in the
electronic device 1 according to Embodiment 1.
[0095] Cooling of the electronic components of the electronic device 5 with the15
above structure is described below. When the vehicle 100 is traveling, as in Embodiment
1, passing air receives heat from the fins 28 and cools the electronic components, more
specifically, the switching elements SW1, SW2, and SW3.
[0096] When the vehicle 100 is stopped, no passing air occurs. As in Embodiment
1, a portion of the air heated with heat transferred from the fins 28 and the branch pipes 2520
moves vertically upward through the spaces between the fins 28, as indicated by the arrows
AR2 in FIG. 26. Other portions of the air heated with heat transferred from the fins 28
and the branch pipes 25 move vertically upward through the through-holes 28a in the fins
28, as indicated by the arrows AR6. The air that has moved vertically upward in the
above manner flows out of the cover 30 through the second vents 36a in the lid 36. For25
simplicity, FIG. 26 illustrates a portion of the airflow.
[0097] When air inside the cover 30 flows out through the second vents 36a, as in
28
Embodiment 1, air outside the cover 30 flows into the cover 30 through the first vents 31a
in the side wall 31 of the cover 30 as indicated by the arrows AR3. Although not
illustrated in FIG. 26, as in Embodiment 1, air outside the cover 30 also flows into the cover
30 through the first vents 31a in the surfaces of the side wall 31 intersecting with Y-
direction.5
[0098] The air flowing into the cover 30 receives heat transferred from the fins 28
and the branch pipes 25 to be heated, moves vertically upward through the spaces between
the fins 28 or the through-holes 28a in the fins 28 as described above, and flows out of the
cover 30 through the second vents 36a. The switching elements SW1, SW2, and SW3
can thus be cooled through such natural convection also when the vehicle 100 is stopped.10
[0099] Both when the vehicle 100 is traveling and when the vehicle 100 is stopped,
heat is transferred to the inner surfaces of the lid 36 by thermal radiation from the fins 28
located at the vertical upper end to cool the switching elements SW1, SW2, and SW3.
[0100] As described above, the ratio of the open areas of the second vents 36a to the
areas of the outer surfaces of the lid 36 of the cover 30 included in the electronic device 515
according to Embodiment 5 is lower than the ratio of the open areas of the first vents 31a
to the areas of the outer surfaces of the side wall 31. The second vents 35a are located to
face the second main surface 21b across the spaces between the fins 28 and to face the
through-holes 28a in the fins 28. Thus, the ratio of the open areas of the second vents 36a
to the areas of the outer surfaces of the lid 36 is lower than in Embodiment 1. The20
structure can further lower the likelihood of reduced thermal radiation from the fins 28
resulting from exposure to sunlight. Thus, the electronic device 5 has higher cooling
performance for the electronic components in sunny weather.
[0101] The fins 28 have the through-holes 28a, and the second vents 36a in the lid
36 are located to face the second main surface 21b across the spaces between the fins 2825
and to face the through-holes 28a. Thus, air heated with heat transferred from the fins 28
and the branch pipes 25 moves vertically upward through the spaces between the fins 28
29
and through the through-holes 28a in the fins 28, and flows out of the cover 30 through the
second vents 36a in the lid 36. Air thus smoothly moves vertically upward through
natural cooling. This increases cooling performance through natural cooling when the
vehicle 100 is stopped.
[0102] Embodiment 65
The cover 30 may have any shape other than in the above examples. An electronic
device 6 according to Embodiment 6 includes a cover 30 with a shape different from the
shape of the cover 30 in Embodiments 1 to 5, and is described focusing on the differences
from Embodiments 1 to 5.
[0103] The electronic device 6 illustrated in FIG. 27 includes a cover 30 including10
the side wall 31 and a lid 37 having a multilayer structure. The lid 37 is attached to the
side wall 31 with the heat transfer members 22 located between the lid 37 and the heat-
receiving block 21. The cover 30 accommodates the heat-receiving block 21, the heat
transfer members 22, and the fins 23 in the space surrounded by the side wall 31 and the
lid 37.15
[0104] The lid 37 includes an outer lid 38 and an inner lid 39 located closer to the
heat-receiving block 21 than the outer lid 38.
[0105] The cover 30 has vents in at least the outer surfaces of the side wall 31
intersecting with X-direction. The ratio of the open areas of the vents to the areas of the
outer surfaces of the side wall 31 is higher than the ratio of the open areas of the vents to20
the areas of the outer surfaces of the lid 37.
[0106] In Embodiment 6, the vents include first vents 31a in outer surfaces of the
side wall 31 as in Embodiment 1, second vents 38a in outer surfaces of the outer lid 38,
and second vents 39a in outer surfaces of the inner lid 39. As in Embodiment 1, the ratio
of the open areas of the vents to the areas of the outer surfaces of the side wall 31 is the25
ratio of the sum of the open areas of the first vents 31a in the outer surfaces of the side wall
31 to the sum of the areas of the outer surfaces of the side wall 31. The ratio of the open
30
areas of the vents to the areas of the outer surfaces of the lid 37 is the ratio of the sum of
the open areas of the second vents 38a in the outer surfaces of the outer lid 38 to the sum
of the areas of the outer surfaces of the outer lid 38, and the ratio of the sum of the open
areas of the second vents 39a in the outer surfaces of the inner lid 39 to the sum of the areas
of the outer surfaces of the inner lid 39. The outer surfaces of the inner lid 39 are surfaces5
of the inner lid 39 opposite to the heat-receiving block 21.
[0107] In Embodiment 6, the ratio of the open areas of the first vents 31a to the areas
of the outer surfaces of the side wall 31 is higher than the ratio of the open areas of the
second vents 38a to the areas of the outer surfaces of the outer lid 38 and higher than the
ratio of the open areas of the second vents 39a to the areas of the outer surfaces of the inner10
lid 39.
[0108] As illustrated in FIG. 27 and FIG. 28 that is a cross-sectional view taken along
line XXVIII-XXVIII in FIG. 27 as viewed in the direction indicated by the arrows, the
second vents 38a in the outer lid 38 and the second vents 39a in the inner lid 39 are
staggered from each other, or in other words, located without the openings facing each15
other. More specifically, the second vents 38a in the outer lid 38 face the portions of the
inner lid 39 having no second vents 39a, or in other words, the portions of the inner lid 39
between the second vents 39a. Similarly, the second vents 39a in the inner lid 39 face the
portions of the outer lid 38 having no second vents 38a, or in other words, the portions of
the outer lid 38 between the second vents 38a.20
[0109] For example, as in Embodiment 2, the outer lid 38 has substantially square
second vents 38a with a length d2 on each side at intervals g2. The inner lid 39 has
substantially square second vents 39a with a length d2 on each side at intervals g2 at
positions not to face the second vents 38a.
[0110] A part of sunlight is thus blocked by the outer lid 38, and another part of25
sunlight that has passed through the second vents 38a in the outer lid 38 is blocked by the
inner lid 39. This structure can thus lower the likelihood of reduced thermal radiation
31
from the fins 23 resulting from exposure to sunlight.
[0111] Cooling of the electronic components of the electronic device 6 with the
above structure is described below. When the vehicle 100 is traveling, as in Embodiment
1, passing air receives heat from the fins 23 and cools the electronic components, more
specifically, the switching elements SW1, SW2, and SW3.5
[0112] When the vehicle 100 is stopped, no passing air occurs. Air heated with heat
transferred from the fins 23 and the branch pipes 25 moves vertically upward through the
spaces between the fins 23, as indicated by the arrows AR7 in FIGS. 29 and 30. The air
that has moved vertically upward flows out of the cover 30 through the second vents 39a
in the inner lid 39 and then through the second vents 38a in the outer lid 38. For simplicity,10
FIGS. 29 and 30 simply illustrate a portion of airflow.
[0113] When the air inside the cover 30 flows out sequentially through the second
vents 39a and 38a, as in Embodiment 1, air outside the cover 30 also flows into the cover
30 through the first vents 31a in the side wall 31 of the cover 30 as indicated by the arrows
AR3.15
[0114] The air flowing into the cover 30 receives heat transferred from the fins 23
and the branch pipes 25 to be heated, moves vertically upward through the spaces between
the fins 23 as described above, and flows out of the cover 30 sequentially through the
second vents 39a and 38a. The switching elements SW1, SW2, and SW3 can thus be
cooled through such natural convection also when the vehicle 100 is stopped.20
[0115] Both when the vehicle 100 is traveling and when the vehicle 100 is stopped,
heat is transferred to the inner surfaces of the lid 37, more specifically, the inner surfaces
of the inner lid 39, by thermal radiation from the fins 23 located at the vertical upper end
to cool the switching elements SW1, SW2, and SW3. The inner surfaces of the inner lid
39 are surfaces of the inner lid 39 adjacent to the heat-receiving block 21.25
[0116] As described above, the cover 30 included in the electronic device 6 according
to Embodiment 6 has the ratio of the open areas of the first vents 31a to the areas of the
32
outer surfaces of the side wall 31 higher than the ratio of the open areas of the second vents
38a to the areas of the outer surfaces of the outer lid 38 and higher than the ratio of the open
areas of the second vents 39a to the areas of the outer surfaces of the inner lid 39. In other
words, the ratio of the open areas of the second vents 38a to the areas of the outer surfaces
of the outer lid 38 and the ratio of the open areas of the second vents 39a to the areas of the5
outer surfaces of the inner lid 39 are lower than the ratio of the open areas of the first vents
31a to the areas of the outer surfaces of the side wall 31. The second vents 38a in the
outer lid 38 and the second vents 39a in the inner lid 39 are staggered from each other.
[0117] As described above, the cover 30 includes the outer lid 38 and the inner lid 39
having vents staggered from each other. The electronic device 6 can lower the likelihood10
of reduced thermal radiation from the fins 23 resulting from exposure to sunlight more
effectively than an electronic device including many vents, such as the first vents 31a,
located uniformly across the full portion of the cover. Sunlight that has passed through
the second vents 38a in the outer lid 38 is blocked by the inner lid 39. This structure can
thus further lower the likelihood of reduced thermal radiation from the fins 23 resulting15
from exposure to sunlight than the structure in Embodiment 1. Thus, the electronic device
6 has higher cooling performance for the electronic components in sunny weather.
[0118] Embodiments of the present disclosure are not limited to the embodiments
described above. Some of the embodiments may be combined as appropriate. For
example, as illustrated in FIG. 31, the electronic device 5 may include fins 29 attached to20
the branch pipes 25 of the heat transfer members 22 with the main surfaces inclined with
respect to the second main surface 21b and having through-holes 29a extending away from
the second main surface 21b.
[0119] Any number of first vents 31a and any number of second vents 32a, 33a, 35a,
36a, 38a, and 39a may be arranged in a manner other than in the above examples in a shape25
or a size other than in the above examples. Any number of first vents 31a and any number
of second vents 32a, 33a, 35a, and 36a in any shape or size may be arranged at any interval
33
in any manner to have the ratio of the open areas of the first vents 31a to the areas of the
outer surfaces of the side wall 31 higher than the ratio of the open areas of the second vents
32a, 33a, 35a, and 36a to the areas of the outer surfaces of the lids 32, 33, 35, and 36.
Similarly, any number of first vents 31a and any number of second vents 38a and 39a in
any shape or size may be arranged at any interval in any manner to have the ratio of the5
open areas of the first vents 31a to the areas of the outer surfaces of the side wall 31 higher
than the ratio of the open areas of the second vents 38a to the areas of the outer surfaces of
the outer lid 38 and higher than the ratio of the open areas of the second vents 39a to the
areas of the outer surfaces of the inner lid 39.
[0120] For example, the first vents 31a and the second vents 32a, 33a, 35a, 36a, 38a,10
and 39a may be, for example, rectangular, circular, or elliptic, rather than square.
[0121] The inverter 14 may supply power to any load, other than the air-conditioner
62, that operates when the vehicle 100 is stopped. In an example, the inverter 14 can
supply power to a light equipment or a door opening and closing device in the vehicle 100.
[0122] The housing 20 may have any shape that can accommodate electronic15
components including the switching elements SW1, SW2, and SW3 and that is attachable
to the roof 100a. In an example, the vertically upper surface of the housing 20 may be
inclined with respect to the horizontal plane for the vehicle 100 located horizontally.
[0123] The heat-receiving block 21 may be a plate having a curved surface
protruding away from the housing 20. As described in the above embodiments, the heat-20
receiving block 21 may be a single plate or a combination of multiple plates.
[0124] Electronic components attached to the heat-receiving block 21 may be, for
example, any electronic components, other than the switching elements SW1, SW2, and
SW3, that are accommodated in the housing 20 such as a thyristor or a diode.
[0125] The heat transfer members 22 may not be heat pipes but may be formed of25
any material that transfers heat away from the second main surface 21b. For example,
the heat transfer members 22 may be rod-like members formed of a highly thermally
34
conductive material including metal such as iron or aluminum.
[0126] The heat transfer members 22 may be arranged in any manner other than in
the above examples to cool electronic components with passing air and through natural
convection. More specifically, the branch pipes 25 of the heat transfer members 22
extending in the positive Z-direction in the above embodiment may extend in a direction5
inclined with respect to Z-axis.
[0127] The headers 24 and the branch pipes 25 may have any shape other than in the
above examples to transfer heat away from the second main surface 21b. In an example,
the header 24 and the branch pipe 25 may be integral with each other and may be a U-
shaped or L-shaped heat pipe as the heat transfer member 22.10
[0128] When taken perpendicular to the extension direction, each heat transfer
member 22 may have an elongated circular cross section rather than a circular cross section.
The elongated circular shape is acquired by deforming a circle to narrow a part of the
dimension, and includes an ellipse, a streamline shape, and an oval. The oval refers to an
outline of perimeters of two circles with the same diameter connected with two straight15
lines.
[0129] The fins 23, 26, 27, 28, and 29 may be formed of the same material, or at least
one of the fins 23, 26, 27, 28, or 29 may be formed of a material different from the material
of the other fins 23, 26, 27, 28, and 29. When at least one of the fins 23, 27, 28, and 29 is
formed of a material different from the material of the other fins 23, 26, 27, 28, and 29, at20
least one of the fins 23, 26, 27, 28, and 29 has thermal conductivity different from the
thermal conductivity of the other fins 23, 26, 27, 28, and 29.
[0130] For example, the fins 23, 26, 27, 28, and 29 located vertically upward may
have higher thermal conductivity than the fins 23, 26, 27, 28, and 29 located vertically
downward. For example, the fins 23, 26, 27, 28, and 29 located vertically upward may25
be formed of copper, and the fins 23, 26, 27, 28, and 29 located vertically downward may
be formed of aluminum.
35
[0131] When other devices are located around the electronic devices 1 to 6, the fins
23, 26, 27, 28, and 29 located vertically upward can more easily come in contact with air
flowing from the outside than the fins 23, 26, 27, 28, and 29 located vertically downward.
The fins 23, 26, 27, 28, and 29 located vertically upward having higher thermal
conductivity than the other fins 23, 26, 27, 28, and 29 can thus increase the cooling5
performance of the electronic devices 1 to 6.
[0132] Any number of fins 23, 26, 27, 28, and 29 in any shape may be arranged in
any manner other than in the above examples. For example, the fins 23, 26, 27, 28, and
29 may be plates with curved surfaces. In another example, the fins 23, 26, 27, 28, and
29 may have different shapes from each other.10
[0133] The cover 30 may have any shape that covers the heat transfer members 22
and the fin 23, 26, 27, 28, or 29 and allows air to flow inside. In an example, the lid 32,
33, 34, 35, 36, or 37 of the cover 30 may have a curved surface. The cover 30 preferably
has a shape that maximizes the inside space within the vehicle limit.
[0134] Each of the electronic devices 1 to 6 may be received in a recess on the roof15
100a of the vehicle 100. FIG. 32 illustrates an example of the electronic device 1 received
in a recess. As illustrated in FIG. 32, the roof 100a of the vehicle 100 includes a container
100b being a recess that is open vertically upward. The electronic device 1 may be
received in the container 100b. A part of the fins 23, 26, 27, 28, and 29 are preferably
located higher than the vertically upper end of the container 100b.20
[0135] Each of the electronic devices 1 to 6 may be any electronic device installable
on the vehicle 100 and including heat-generating electronic components, rather than the
power converter illustrated in FIG. 1. In an example, each of the electronic devices 1 to
6 may be a heat exchanger in an air-conditioner.
[0136] In the above embodiments, each of the electronic devices 1 to 6 cools the25
electronic components with passing air. The electronic devices 1 to 6 may cool electronic
components with air supplied from external devices rather than with the passing air. In
36
an example, the electronic devices 1 to 6 may each cool the electronic components with air
supplied from a fan located adjacent to the electronic devices 1 to 6.
[0137] The electronic devices 1 to 6 is installable on a DC feeding railway vehicle,
rather than on an AC feeding railway vehicle. The electronic devices 1 to 6 are installable
on any vehicle that creates passing air such as a trolley bus or a streetcar, rather than the5
railway vehicle.
[0138] The foregoing describes some example embodiments for explanatory
purposes. Although the foregoing discussion has presented specific embodiments,
persons skilled in the art will recognize that changes may be made in form and detail
without departing from the broader spirit and scope of the invention. Accordingly, the10
specification and drawings are to be regarded in an illustrative rather than a restrictive sense.
This detailed description, therefore, is not to be taken in a limiting sense, and the scope of
the invention is defined only by the included claims, along with the full range of equivalents
to which such claims are entitled.
Reference Signs List15
[0139]
1, 2, 3, 4, 5, 6 Electronic device
1a, 1b Terminal
11, 15 Transformer
12 Converter20
13, 14 Inverter
20 Housing
20a Opening
21 Heat-receiving block
21a First main surface25
21b Second main surface
22 Heat transfer member
37
23, 26, 27, 28, 29 Fin
24 Header
25 Branch pipe
28a, 29a Through-hole
30 Cover5
31 Side wall
31a First vent
32, 33, 34, 35, 36, 37 Lid
32a, 33a, 35a, 36a, 38a, 39a Second vent
38 Outer lid10
39 Inner lid
61 Motor
62 Air-conditioner
100 Vehicle
100a Roof15
100b Container
AR1, AR2, AR3, AR4, AR5, AR6, AR7 Arrow
C1 Capacitor
d1, d2 Length
g1, g2 Interval20
SW1, SW2, SW3 Switching element
38
WE CLAIM:
[Claim1] An electronic device installable on a roof of a vehicle, the electric
device comprising:
a heat-receiving block being heat conductive, the heat-receiving block having a first
main surface to which an electronic component is attachable;5
a heat transfer member attached to the heat-receiving block, the heat transfer
member extending away from a second main surface of the heat-receiving block located
opposite to the first main surface of the heat-receiving block and facing vertically upward,
the heat transfer member being configured to transfer heat transferred from the electronic
component through the heat-receiving block away from the second main surface;10
a plurality of fins attached to the heat transfer member, the plurality of fins being
configured to dissipate heat transferred from the electronic component through the heat-
receiving block and the heat transfer member into ambient air, the plurality of fins being
arranged in at least one of a width direction of the vehicle or a travel direction of the vehicle
with spaces between the plurality of fins; and15
a cover including a side wall and a lid, the side wall extending in a direction
surrounding a normal line to the second main surface, the lid being attached to the side wall
with the heat transfer member located between the lid and the heat-receiving block, the
cover accommodating the heat transfer member and the plurality of fins in a space
surrounded by the side wall and the lid, wherein20
the cover has a vent in at least an outer surface of the side wall intersecting with the
travel direction of the vehicle, and a ratio of an open area of the vent on the side wall to an
area of the outer surface of the side wall is higher than a ratio of an open area of the vent
on the lid to an area of an outer surface of the lid.
25
[Claim 2] The electronic device according to claim 1, further comprising:
a housing accommodating the electronic component, having an opening in a
39
vertically upper portion of the housing, and installable on the roof of the vehicle, wherein
the heat-receiving block is attached to the housing with the first main surface closing
the opening of the housing.
[Claim 3] The electronic device according to claim 1 or 2, wherein5
the vent in the cover is located in the side wall alone.
[Claim 4] The electronic device according to claim 1 or 2, wherein
the vent includes a first vent in at least a surface of the side wall intersecting with the
travel direction and a second vent in the lid, and10
a ratio of an open area of the first vent to the area of the outer surface of the side wall
intersecting with the travel direction is higher than a ratio of an open area of the second
vent to the area of the outer surface of the lid.
[Claim 5] The electronic device according to claim 4, wherein15
the open area of the first vent is larger than the open area of the second vent.
[Claim 6] The electronic device according to claim 4 or 5, wherein
a plurality of the first vents is located in at least the surface of the side wall
intersecting with the travel direction,20
a plurality of the second vents is located in the lid, and
adjacent first vents of the plurality of first vents are at a smaller interval than adjacent
second vents of the plurality of second vents.
[Claim 7] The electronic device according to any one of claims 4 to 6, wherein25
the lid has the second vent at a position facing the second main surface across the
spaces between the plurality of fins.
40
[Claim 8] The electronic device according to any one of claims 4 to 7, wherein
each of the plurality of fins has a through-hole extending therethrough away from
the second main surface, and
the lid has the second vent at a position facing the through-hole.5
[Claim 9] The electronic device according to any one of claims 4 to 8, wherein
the lid includes an outer lid and an inner lid located closer to the heat-receiving block
than the outer lid, and
the second vent in the outer lid and the second vent in the inner lid are staggered10
from each other.