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 100-8310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
2
DESCRIPTION
5 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
vehicle dissipates heat generated by electronic components with a cooler into airflow
10 created by the traveling vehicle to cool the electronic components. Patent Literature 1
describes an example of such an electronic device. The power converter described in
Patent Literature 1 is attached to the roof of a railway vehicle, and includes fins attached
to an upper surface and a side surface of a housing.
Citation List
15 Patent Literature
[0003] Patent Literature 1: Unexamined Japanese Patent Application Publication
No. 2009-124038
Summary of Invention
Technical Problem
20 [0004] The power converter described in Patent Literature 1 flows airflow created
by a traveling railway vehicle between the fins to cool electronic components, such as a
semiconductor element, accommodated in the housing of the power converter. The
power converter supplies power to electronic devices installed on the railway vehicle, for
example, an air-conditioning device or a lighting device, and operates when the railway
25 vehicle is traveling as well as when the railway vehicle is stopped. Thus, the electronic
components in the power converter generate heat also when the railway vehicle is
stopped.
3
[0005] The above electronic components in the power converter described in Patent
Literature 1 generate heat also when the railway vehicle is stopped. The electronic
components are thus not fully cooled when the railway vehicle is stopped. In other
words, the power converter described in Patent Literature 1 has insufficient cooling
5 performance through natural convection. This issue is common to the power converter
that supplies power to, for example, the air-conditioning device or the lighting device
installed on the railway vehicle as well as to an electronic device including electronic
components that generate heat when a vehicle is stopped, in addition to when the vehicle
is traveling.
10 [0006] In response to the above circumstances, an objective of the present
disclosure is to provide an electronic device that can cool electronic components also
when a vehicle is stopped.
Solution to Problem
[0007] To achieve the above objective, an electronic device according to an aspect
15 of the present disclosure includes a heat conductive heat-receiving block, a heat transfer
member, and one or more fins. The heat-receiving block has a first main surface to
which an electronic component is attached. The heat transfer member is attached to a
second main surface of the heat-receiving block. The second main surface is opposite to
the first main surface. The heat transfer member extends away from the second main
20 surface to transfer heat transferred from the electronic component through the heatreceiving block in a direction away from the second main surface. The one or more fins
have main surfaces, and are attached to the heat transfer member with the main surfaces
being inclined with respect to a horizontal plane for the vehicle being located
horizontally. The one or more fins dissipate heat transferred from the electronic
25 component through the heat-receiving block and the heat transfer member into ambient
air.
Advantageous Effects of Invention
4
[0008] The electronic device according to the above aspect of the present disclosure
includes the heat transfer member to transfer heat from the electronic component, and the
one or more fins attached to the heat transfer member with the main surfaces inclined
with respect to a horizontal plane for the vehicle being located horizontally. The fins
5 dissipate heat transferred from the electronic component into air. Thus, the electronic
device can cool the electronic component also when the vehicle is stopped.
Brief Description of Drawings
[0009] FIG. 1 is a block diagram of an electronic device according to Embodiment
1;
10 FIG. 2 is a diagram of the electronic device according to Embodiment 1,
illustrating an example installation on a vehicle;
FIG. 3 is a cross-sectional view of the electronic device according to Embodiment
1 taken along line III-III as viewed in the direction indicated by the arrows in FIG. 2;
FIG. 4 is a cross-sectional view of the electronic device according to Embodiment
15 1 taken along line IV-IV as viewed in the direction indicated by the arrows in FIG. 3;
FIG. 5 is a diagram of the electronic device according to Embodiment 1,
illustrating example airflow;
FIG. 6 is a diagram of fins located horizontally, illustrating example natural
convection around the fins;
20 FIG. 7 is a diagram of the fins in Embodiment 1, illustrating example natural
convection around the fins;
FIG. 8 is a diagram of the electronic device according to Embodiment 1,
illustrating an example flow of natural convection;
FIG. 9 is a diagram of an electronic device according to Embodiment 2, illustrating
25 an example installation on a vehicle;
FIG. 10 is a cross-sectional view of the electronic device according to Embodiment
2 taken along line X-X as viewed in the direction indicated by the arrows in FIG. 9;
5
FIG. 11 is a diagram of the electronic device according to Embodiment 2,
illustrating example natural convection;
FIG. 12 is a cross-sectional view of an electronic device according to Embodiment
3;
5 FIG. 13 is a cross-sectional view of the electronic device according to Embodiment
3 taken along line XIII-XIII as viewed in the direction indicated by the arrows in FIG. 12;
FIG. 14 is a diagram of the electronic device according to Embodiment 3,
illustrating an example flow of natural convection;
FIG. 15 is a cross-sectional view of an electronic device according to Embodiment
10 4;
FIG. 16 is a cross-sectional view of the electronic device according to Embodiment
4 taken along line XVI-XVI as viewed in the direction indicated by the arrows in FIG.
15;
FIG. 17 is a cross-sectional view of an electronic device according to a first
15 modification of an embodiment;
FIG. 18 is a cross-sectional view of an electronic device according to a second
modification of an embodiment;
FIG. 19 is a cross-sectional view of an electronic device according to a third
modification of an embodiment;
20 FIG. 20 is a cross-sectional view of an electronic device according to a fourth
modification of an embodiment;
FIG. 21 is a cross-sectional view of an electronic device according to the fourth
modification of an embodiment; and
FIG. 22 is a cross-sectional view of an electronic device according to a fifth
25 modification of an embodiment.
Description of Embodiments
[0010] An electronic device according to one or more embodiments of the present
6
disclosure is described below in detail with reference to the drawings. In the figures, the
same reference signs denote the same or equivalent components.
[0011] Embodiment 1
As an example of an electronic device, a power converter is installable on a
5 railway 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 Embodiment 1 is described using, in an
example, a power converter installed on the roof of a railway vehicle to cool electronic
components through natural convection and airflow, the airflow being airflow caused by
10 a traveling railway vehicle and flowing in a direction opposite to the travel direction of
the railway vehicle.
[0012] 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-conditioning device 62 serving as example loads,
15 and supplies the resulting AC power to the motor 61 and the air-conditioning device 62.
The motor 61 is, for 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, or more specifically, during power running, the
motor 61 generates propulsion of the railway vehicle. The air-conditioning device 62 is
20 an air conditioner in the railway vehicle. When the electronic device 1 supplies power
to the air-conditioning device 62 during the operation of the railway vehicle, or more
specifically, during traveling or stopping of the railway vehicle, the air-conditioning
device 62 operates to adjust the temperature in the railway vehicle to an intended
temperature.
25 [0013] The components of the electronic device 1 are described below. The
electronic device 1 includes an input terminal 1a connected to the power supply and an
input terminal 1b grounded. The electronic device 1 further includes a transformer 11
7
that lowers the voltage of AC power supplied from the power supply connected to the
input terminal 1a, a converter 12 that converts the AC power having the voltage lowered
by the transformer 11 to 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
5 the capacitor C1 to AC power.
[0014] The input terminal 1a is electrically connected to, for example, a current
collector that acquires AC power supplied from an electrical substation through a power
line. For example, the power line is an overhead power line or a third rail. The current
collector is a pantograph or a current collector shoe. The input terminal 1b is short10 circuited to rails through a ground brush, which is not illustrated, and is grounded.
[0015] The transformer 11 includes a primary winding having one end connected to
the input terminal 1a and the other end connected to the input 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
15 collector to single-phase AC power with a voltage of 1520 V, and supplies the AC power
with the lowered voltage to the converter 12.
[0016] 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
20 winding of the transformer 11 is connected to the connecting 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 the connecting point of the two switching elements SW1 in the other
pair.
[0017] Each switching element SW1 includes an insulated-gate bipolar transistor
25 (IGBT) and a freewheeling diode including an anode connected to an emitter terminal of
the IGBT and a cathode connected to a collector terminal of the IGBT. A controller,
which is not illustrated, provides a gate signal to a gate terminal of the IGBT included in
8
each switching 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.
5 [0018] The capacitor C1 is charged with DC power output from the converter 12.
The capacitor C1 has one end connected to a connecting point between a positive
terminal of the converter 12 and primary positive terminals of the inverters 13 and 14,
and the other end connected to a connecting point between a negative terminal of the
converter 12 and primary negative terminals of the inverters 13 and 14.
10 [0019] The inverter 13 includes three pairs of two switching elements SW2 that are
connected in series. The three pairs of switching elements SW2 correspond to a U
phase, a V phase, and a W phase of three-phase AC power, respectively . 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
15 connected parallel to one another. Similarly to the switching elements SW1, each
switching element SW2 includes an IGBT and a freewheeling diode. A controller,
which is not illustrated, provides a gate signal to a gate terminal of the IGBT included in
each switching element SW2 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
20 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 are
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, respectively. The
25 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. Similarly to the switching elements SW1,
9
each switching element SW3 includes an IGBT and a freewheeling diode. A controller,
which is not illustrated, provides a gate signal to a 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 off the switching element SW3. Each switching element
5 SW3 performs switching to cause the inverter 14 to convert DC power to three-phase AC
power.
[0021] 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 airconditioning device 62. The three-phase AC power with the voltage lowered by the
10 transformer 15 is supplied to the air-conditioning device 62.
[0022] When the railway vehicle is traveling, the converter 12 and the inverters 13
and 14 are in operation. Thus, the switching elements SW1, SW2, and SW3 are
repeatedly turned on and off, or more specifically, perform switching and generate heat.
When the railway vehicle is stopped, the motor 61 receives no power, but the air15 conditioning device 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
and generate heat. Thus, the electronic device 1 cools electronic components including
20 the switching elements SW1, SW2, and SW3 with airflow created by the traveling
railway vehicle, and cools electronic components including the switching elements SW1
and SW3 through natural convection when the railway vehicle is stopped.
[0023] 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.
25 As illustrated in FIG. 3 that is a cross-sectional view of the electronic device 1 taken
along line III-III as viewed in the direction indicated by the arrows in FIG. 2, the
electronic device 1 includes a housing 20 located on the roof 100a and accommodating
10
electronic components including the switching elements SW1, SW2, and SW3, and a
heat-receiving block 21 that is heat conductive and attached to the housing 20 to cover an
opening 20a of the housing 20. The heat-receiving block 21 has a first main surface 21a
receiving electronic components. The electronic device 1 further includes heat transfer
5 members 22 and fins 23. The heat transfer members 22 are attached to a second main
surface 21b of the heat-receiving block 21, and transfer heat transferred from the
electronic components through the heat-receiving block 21 in a direction away from the
second main surface 21b. The fins 23 are attached to the heat transfer members 22, and
dissipate heat transferred from the electronic components through the heat-receiving
10 block 21 and the heat transfer members 22 into air.
[0024] To suppress breakage of the heat transfer members 22 and the fins 23, the
electronic device 1 preferably includes a cover 30 attached to the housing 20 to cover the
heat transfer members 22 and the fins 23.
[0025] In FIGS. 2 and 3, Z-axis indicates a vertical direction for the vehicle 100
15 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.
[0026] The housing 20 is attached to a vertically upper portion of the roof 100a.
The housing 20 has such high rigidity and strength as to resist deformation under the
20 maximum expected vibration from the railway vehicle. For example, the housing 20 is
formed from metal such as iron or aluminum. The housing 20 has the opening 20a in a
vertically upper portion.
[0027] The heat-receiving block 21 is attached to the housing 20 to cover the
opening 20a. In Embodiment 1, the heat-receiving block 21 is a plate of a highly
25 thermally conductive material including metal such as iron or aluminum, and is attached
to the outer surface of the housing 20 to cover the opening 20a. Electronic components
that generate heat, or more specifically, the switching elements SW1, SW2, and SW3, are
11
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 surface
21a. For the vehicle 100 located horizontally, the first main surface 21a and the second
main surface 21b extend horizontally.
5 [0028] Each heat transfer member 22 extends away from the second main surface
21b, and transfers heat transferred from the electronic components through the heatreceiving block 21 in a direction away from the second main surface 21b. In
Embodiment 1, each heat transfer member 22 includes a heat pipe that contains a coolant
therein. More specifically, each heat transfer member 22 serving as a heat pipe includes
10 a header 24a attached to the heat-receiving block 21 and a branch pipe 24b attached to the
header 24a and continuous with the header 24a. The header 24a and the branch pipe
24b contain a coolant in vapor and liquid phases at ordinary temperature. An example
of the coolant is water.
[0029] As illustrated in FIG. 3 and FIG. 4 that is a cross-sectional view taken along
15 line IV-IV as viewed in the direction indicated by the arrows in FIG. 3, multiple headers
24a extending in X-direction are arranged in Y-direction. In Embodiment 1, eight
headers 24a extending in X-direction are arranged in Y-direction. Each header 24a 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,
20 welding, or soldering. Each header 24a is a pipe formed from a highly thermally
conductive material including metal such as iron or aluminum. Each header 24a
receives multiple branch pipes 24b.
[0030] When the vehicle 100 is traveling, airflow heated with heat transferred from
the fins 23 at the front in the travel direction of the vehicle 100 flows rearward in the
25 travel direction of the vehicle 100. Thus, the electronic device 1 may fail to sufficiently
cool electronic components located at the rear in the travel direction of the vehicle 100
compared with electronic components located at the front in the travel direction of the
12
vehicle 100. As described above, the headers 24a extending in X-direction and
convection of the coolant in the headers 24a facilitate dispersion of heat in X-direction,
and reduce variations in cooling the electronic components arranged in X-direction.
[0031] Each branch pipe 24b extends in Z-direction. Each branch pipe 24b is
5 attached to the corresponding header 24a by, for example, welding or soldering and
continuous with the header 24a. Each branch pipe 24b is a pipe formed from a highly
thermally conductive material including metal such as iron or aluminum. Each branch
pipe 24b has a dimension below a vehicle limit in the cross section taken perpendicular to
the travel direction of the vehicle 100, or more specifically, a YZ plane. The vehicle
10 limit indicates a maximum dimension of the vehicle 100. In Embodiment 1, the branch
pipes 24b have different dimensions corresponding to the vehicle limit. More
specifically, the dimension of the branch pipes 24b in Z-direction attached to the two
headers 24a at two ends in Y-direction is shorter than the dimension of the branch pipes
24b in Z-direction attached to the four headers 14a at the center in Y-direction.
15 [0032] The fins 23 are attached to the heat transfer members 22. More
specifically, the fins 23 are attached to the heat transfer members 22 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
20 Embodiment 1, the fins 23 are plates of a highly thermally conductive material including
metal such as iron or aluminum.
[0033] To enhance the cooling performance of the electronic components when the
vehicle 100 is traveling, the main surfaces of the fins 23 is preferably parallel to X-axis.
The airflow created by the traveling vehicle 100 flows in X-direction. Thus, the fins 23
25 having the main surfaces parallel to X-axis can efficiently transfer heat to airflow flowing
between the fins 23. This structure can cool the electronic components including the
switching elements SW1, SW2, and SW3.
13
[0034] To cool electronic components through natural convection when the vehicle
100 is stopped, the fins 23 are attached to the heat transfer members 22 with the main
surfaces inclined with respect to the horizontal plane for the vehicle 100 located
horizontally. The main surfaces inclined with respect to the horizontal plane refer to the
5 main surfaces that are not parallel to the horizontal plane. The main surfaces of the fins
23 inclined with respect to the horizontal plane allow air heated with heat transferred
from the fins 23 to move vertically upward along the fins 23. This airflow causes
outside air to flow in, and transfers heat from the fins 23 to the inflow air. The main
surfaces of the fins 23 inclined with respect to the horizontal plane cause this airflow and
10 thus can cool the electronic components including the switching elements SW1, SW2,
and SW3.
[0035] In Embodiment 1, the multiple fins 23 are arranged in Y-direction and Zdirection. As illustrated in FIG. 3, four fins 23 are arranged in Y-direction. The fins
23 at each end in Y-direction are four fins 23 arranged in Z-direction. The fins 23 at the
15 center in Y-direction are seven fins 23 arranged in Z-direction. The fins 23 at the two
ends in Y-direction are attached to the heat transfer members 22, or more specifically, to
the branch pipes 24b with one end 231 of each fin 23 nearer the center of the vehicle 100
in Y-direction located vertically higher than the other end 232 of each fin 23 for the
vehicle 100 located horizontally. In other words, the fins 23 at the two ends in Y20 direction are attached to the heat transfer members 22 to be higher toward the center in Ydirection, rather than being attached horizontally.
[0036] The fins 23 at the center in Y-direction are attached to the heat transfer
members 22, or more specifically, to the branch pipes 24b with one end 231 of each fin
23 nearer the center of the vehicle 100 in Y-direction located vertically lower than the
25 other end 232 of each fin 23 for the vehicle 100 located horizontally. In other words,
the fins 23 at the center in Y-direction are attached to the heat transfer members 22 to be
higher toward the ends in Y-direction, rather than being attached horizontally.
14
[0037] The cover 30 is attached to the housing 20 to cover the heat-receiving block
21, the heat transfer members 22, and the fins 23. The cover 30 has multiple ventilation
holes 30a in a surface extending along X-axis. The ventilation holes 30a allow outside
air to flow into the cover 30, and allow air flowing near the heat transfer members 22 and
5 the fins 23 to flow out of the cover 30. As illustrated in FIG. 4, the cover 30 has
multiple ventilation holes 30b in surfaces perpendicular to X-axis. The ventilation holes
30b allow outside air to flow into the cover 30, and allow air flowing near the heat
transfer members 22 and the fins 23 to flow out of the cover 30.
[0038] Cooling of electronic components of the electronic device 1 with the above
10 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 24a. Thus, the coolant evaporates. The evaporated coolant moves in
the branch pipes 24b in the positive Z-direction. The coolant transfers heat to air around
the heat transfer members 22 through the branch pipes 24b and the fins 23 while moving
15 in the positive Z-direction, and is cooled and liquefies. The liquefied coolant moves in
the negative Z-direction along the inner walls of the branch pipes 24b. As described
above, the coolant circulates while repeatedly evaporating and liquefying to transfer heat
generated by at least one of the switching elements SW1, SW2, and SW3 to air around
the heat transfer members 22, and to cool the switching elements SW1, SW2, and SW3
20 generating heat.
[0039] For example, when the vehicle 100 travels in the positive X-direction,
airflow flowing in the negative X-direction as indicated by arrow AR1 in FIG. 5 occurs.
For simplicity, FIG. 5 simply illustrates a part of airflow. The airflow flows between the
fins 23. The airflow flowing between the fins 23 receives heat transferred from the fins
25 23 and cools the switching elements SW1, SW2, and SW3.
[0040] When the vehicle 100 is stopped, no airflow illustrated in FIG. 5 occurs.
Air heated with heat transferred from the fins 23 has lower density than distant air at
15
ordinary temperature, for example, air outside the cover 30. When buoyancy caused by
the difference in air density exceeds the air viscous force, air flows around the fins 23.
The ratio of the buoyancy to the viscous force in natural convection is expressed by the
Grashof number Gr in Formula 1 below. Higher Grashof numbers Gr are more likely to
5 cause natural convection.
[0041]
(1)
[0042] In Formula 1, g denotes gravitational acceleration (in m/s2 10 ). β denotes the
coefficient of cubical expansion (in 1/K) of a fluid, or more specifically, air. ΔT denotes
a representative temperature difference, or more specifically, a temperature difference
between a heating body and the fluid, or the temperature difference (in K) between the
fins 23 and air. L denotes a representative dimension, or more specifically, a dimension
15 of the heating body along airflow, for example, a dimension of the fins 23 along airflow
in the YZ plane. ν denotes a coefficient of kinematic viscosity (in m2
/s) of a fluid, or
more specifically, air.
[0043] As illustrated in FIG. 6, in a known electronic device including fins 41
having the main surfaces horizontally attached to heat pipes 42 for the vehicle located
20 horizontally, the dimension of the fins along airflow flowing vertically upward is the
vertical dimension of the side surfaces of the fins that come in contact with air flowing
vertically upward, and is thus sufficiently small. Thus, the Grashof number Gr is small.
In other words, natural convection is less likely to occur. Although natural convection
occurs slightly and transfers heat from the fins 41 located vertically downward or
25 vertically lower portions of the heat pipes 42 to move air vertically upward, the fins 41
located horizontally at positions vertically upward interrupt air transfer. Thus, air
stagnates as indicated by the arrows in FIG. 6 in spaces defined by the heat pipes 42
16
adjacent to one another in Y-direction and the fins 41 adjacent to one another in Zdirection. Thus, a known electronic device including the fins 41 having the main
surfaces located horizontally has insufficient cooling performance through natural
convection.
5 [0044] In the electronic device 1 according to Embodiment 1, in contrast, the fins
23 are attached to the heat transfer members 22 with the main surfaces inclined with
respect to the horizontal plane. The electronic device 1 thus has a larger representative
dimension L, and has a higher Grashof number Gr than a known electronic device
including horizontally extending fins. In other words, the electronic device 1 is more
10 likely to cause natural convection than a known electronic device including horizontally
extending fins. As illustrated in FIG. 7, air that has received heat transferred from the
fins 23 located vertically downward or vertically lower portions of the branch pipes 24b
moves vertically upward, and further moves vertically upward along the fins 23 inclined
with respect to the horizontal plane.
15 [0045] Thus, as indicated by arrows AR2 in FIG. 8, air inside the cover 30 receives
heat transferred from the fins 23 to be heated and moves vertically upward along the fins
23. Air moving vertically upward flows through the ventilation holes 30a in the
vertically upper portion of the cover 30, and flows out of the cover 30. When air inside
the cover 30 flows out through the ventilation holes 30a, air outside the cover 30 flows
20 into the cover 30 through the ventilation holes 30a in the side surfaces of the cover 30 as
indicated by arrows AR3. In addition, air outside the cover 30 flows into the cover 30
through the ventilation holes 30b not illustrated in FIG. 8. For simplicity, FIG. 8 simply
illustrates a part of airflow.
[0046] As described above, air flowing into the cover 30 receives heat transferred
25 from the fins 23 to be heated and moves vertically upward along the fins 23, and flows
out of the cover 30 through the ventilation holes 30a. The fins 23 attached to the heat
transfer members 22 with the main surfaces inclined with respect to the horizontal plane
17
cause airflow moving vertically upward along the fins 23. The switching elements
SW1, SW2, and SW3 can thus be cooled through natural convection in this manner also
when the vehicle 100 is stopped.
[0047] As the angle between the main surfaces of the fins 23 and the horizontal
5 plane increases for the vehicle 100 located horizontally, the representative dimension L in
Formula 1 increases, and the Grashof number Gr also increases. Thus, the electronic
device 1 enhances cooling performance through natural convection. However, when the
angle between the main surfaces of the fins 23 and the horizontal plane increases for the
vehicle 100 located horizontally, the dimension of each fin in Z-direction increases, and
10 thus the electronic device 1 can install fewer fins 23 below the vehicle limit. The fewer
fins 23 reduce the dissipation area and lower the cooling performance. Thus, the angle
between the main surfaces of the fins 23 and the horizontal plane for the vehicle 100
located horizontally is preferably determined based on the cooling performance through
natural convection and the space that can receive the fins 23.
15 [0048] In Embodiment 1, for example, the angle between the main surfaces of the
fins 23 and the horizontal plane in the YZ plane for the vehicle 100 located horizontally is
preferably within a range of less than or equal to 15 degrees. More specifically, the
angle between the main surfaces of the fins 23 and the horizontal plane in the YZ plane is
preferably within a range of 5 to 15 degrees inclusive.
20 [0049] As described above, the electronic device 1 according to Embodiment 1
includes the fins 23 attached to the heat transfer members 22 with the main surfaces
inclined with respect to the horizontal plane for the vehicle 100 located horizontally.
When the vehicle 100 is stopped, air heated with heat transferred from the fins 23 moves
vertically upward along the fins 23. The fins 23 inclined with respect to the horizontal
25 plane cause airflow moving vertically upward along the fins 23. Thus, the electronic
device 1 can cool electronic components including the switching elements SW1, SW2,
and SW3 through natural convection also when the vehicle 100 is stopped.
18
[0050] Embodiment 2
The electronic device 1 may be at any position, and the heat transfer members 22
and the fins 23 may be arranged in any manner other than in the above example to cool
the electronic components through natural convection. In an example, an electronic
5 device 2 according to Embodiment 2 includes heat transfer members 22 located in a
container 100b on the roof 100a of the vehicle 100. The heat transfer members 22
extend at an acute angle with respect to the second main surface 21b.
[0051] As illustrated in FIG. 9, the roof 100a of the vehicle 100 includes the
container 100b being a recess that is open vertically upward. More specifically, the
10 surface of the container 100b with the opening is flush with the vertically upper end of
the roof 100a of the vehicle 100. The container 100b accommodates the housing 20 in
the electronic device 2. More specifically, the bottom surface of the housing 20 is
attached to the bottom surface of the container 100b.
[0052] To enhance the cooling performance, at least parts of the heat transfer
15 members 22 and at least parts of the fins 23 are preferably located vertically above the
upper end of the roof 100a.
[0053] The electronic device 2 includes the same components as the electronic
device 1 according to Embodiment 1, but differs from the electronic device 1 in the
arrangement of the heat transfer members 22 and the fins 23. More specifically, as
20 illustrated in FIG. 10 that is a cross-sectional view taken along line X-X as viewed in the
direction indicated by the arrows in FIG. 9, the heat transfer members 22 extend at an
acute angle with respect to the second main surface 21b. More specifically, each heat
transfer member 22 includes headers 24a that are the same as the headers 24a in
Embodiment 1, and branch pipes 24b attached to the headers 24a to extend at an acute
25 angle with respect to the second main surface 21b. In Embodiment 2, each branch pipe
24b extends away from the second main surface 21b and extends from the center of the
vehicle 100 in the width direction toward an end of the vehicle 100 in the width direction.
19
FIG. 10 illustrates, with two-dot-dash lines, an extension direction D1 of the branch pipes
24b in the heat transfer members 22 located in the negative Y-direction from the center of
the vehicle 100 in Y-direction and an extension direction D2 of the branch pipes 24b in
the heat transfer members 22 located in the positive Y-direction from the center of the
5 vehicle 100 in Y-direction. An angle θ1 between the extension direction D1 and the
second main surface 21b and an angle θ2 between the extension direction D2 and the
second main surface 21b are acute angles.
[0054] More specifically, eight headers 24a are attached to the second main surface
21b in Y-direction. The branch pipes 24b attached to the four headers 24a located in the
10 negative Y-direction from the center of the second main surface 21b in Y-direction
extend away from the second main surface 21b and extend in the negative Y-direction.
The branch pipes 24b attached to the four headers 24a located in the positive Y-direction
from the center of the second main surface 21b in Y-direction extend away from the
second main surface 21b and extend in the positive Y-direction.
15 [0055] The fins 23 are attached to the heat transfer members 22 with the main
surfaces inclined with respect to the horizontal plane for the vehicle 100 located
horizontally. More specifically, the fins 23 are attached to the heat transfer members 22
with the main surfaces perpendicular to the extension direction of the branch pipes 24b.
The heat transfer members 22 extend at an acute angle with respect to the second main
20 surface 21b, and thus the main surfaces of the fins 23 perpendicular to the extension
direction of the branch pipes 24b are inclined with respect to the second main surface
21b. The second main surface 21b extends horizontally for the vehicle 100 located
horizontally. Thus, the main surfaces of the fins 23 are inclined with respect to the
horizontal plane.
25 [0056] In Embodiment 2, each fin 23 has, in Y-direction, one end 231 nearer the
center of the vehicle 100 located vertically higher than the other end 232.
[0057] When the vehicle 100 is traveling, as in Embodiment 1, airflow flows
20
between the fins 23 to receive heat transferred from the fins 23 and cools the switching
elements SW1, SW2, and SW3.
[0058] When the vehicle 100 is stopped, no airflow occurs. As described above,
the fins 23 are attached to the branch pipes 24b with the main surfaces perpendicular to
5 the extension direction of the branch pipes 24b extending at an acute angle with respect to
the second main surface 21b. Thus, as indicated by arrows AR4 in FIG. 11, air inside
the cover 30 receives heat transferred from the fins 23 to be heated and moves vertically
upward along the fins 23. Air moving vertically upward flows out of the cover 30
through the ventilation holes 30a. When the air inside the cover 30 flows out through
10 the ventilation holes 30a, air outside the cover 30 flows into the cover 30 through the
ventilation holes 30a as indicated by arrows AR5. In addition, air outside the cover 30
flows into the cover 30 through the ventilation holes 30b not illustrated in FIG. 11. For
simplicity, FIG. 11 simply illustrates a part of airflow.
[0059] As described above, air flowing into the cover 30 receives heat transferred
15 from the fins 23 to be heated and moves vertically upward along the fins 23, and flows
out of the cover 30 through the ventilation holes 30a. The fins 23 attached to the branch
pipes 24b cause airflow moving vertically upward along the fins 23, with the main
surfaces perpendicular to the extension direction of the branch pipes 24b extending at an
acute angle with respect to the second main surface 21b. The switching elements SW1,
20 SW2, and SW3 can thus be cooled through natural convection also when the vehicle 100
is stopped.
[0060] As the acute angle between the extension direction of the branch pipes 24b
and the second main surface 21b decreases, or in other words, as the angles θ1 and θ2 in
FIG. 10 decrease, the representative dimension L in Formula 1 increases, and the Grashof
25 number Gr also increases. Thus, the electronic device 1 enhances cooling performance
through natural convection. However, when the acute angle between the extension
direction of the branch pipes 24b and the second main surface 21b decreases, the
21
dimension of each branch pipe 24b in Z-direction increases. Thus, the electronic device
1 can install fewer branch pipes 24b below the vehicle limit. The fewer branch pipes
24b reduce the fins 23 attached to the branch pipes 24b below the vehicle limit. The
fewer fins 23 reduce the dissipation area and lower the cooling performance. Thus, the
5 acute angle between the extension direction of the branch pipes 24b and the second main
surface 21b may be determined based on the cooling performance through natural
convection and the space that can receive the fins 23.
[0061] For example, the acute angle between the extension direction of the branch
pipes 24b and the second main surface 21b may be greater than or equal to 75 degrees.
10 More specifically, the acute angle between the extension direction of the branch pipes
24b and the second main surface 21b may be 75 to 85 degrees inclusive.
[0062] As described above, the electronic device 2 according to Embodiment 2
includes the heat transfer members 22 that extend at an acute angle with respect to the
second main surface 21b, and the fins 23 attached to the heat transfer members 22 with
15 the main surfaces perpendicular to the extension direction of the heat transfer members
22. When the vehicle 100 is stopped, air heated with heat transferred from the fins 23
moves vertically upward along the fins 23. The fins 23 inclined with respect to the
horizontal plane cause airflow moving vertically upward along the fins 23. Thus, the
electronic device 2 can cool the electronic components including the switching elements
20 SW1, SW2, and SW3 through natural convection also when the vehicle 100 is stopped.
[0063] Embodiment 3
The heat transfer members 22 may have any shape and the fins 23 may be located
at any positions other than in the above examples to cool the electronic components with
airflow and natural convection. An electronic device 3 according to Embodiment 3
25 includes heat transfer members and fins different from the heat transfer members and the
fins in Embodiments 1 and 2 and is described focusing on the differences from the
electronic devices 1 and 2.
22
[0064] As illustrated in FIG. 12 and FIG. 13 that is a cross-sectional view taken
along line XIII-XIII as viewed in the direction indicated by the arrows in FIG. 12, the
electronic device 3 according to Embodiment 3 includes heat transfer members 51
attached to the heat-receiving block 21 to transfer heat transferred from the electronic
5 components through the heat-receiving block 21 in a direction away from the second
main surface 21b, and fins 52 attached to the heat transfer members 51 to dissipate heat
transferred from the electronic components through the heat-receiving block 21 and the
heat transfer members 51 into air. The heat transfer members 51 are arranged in Xdirection and Y-direction. The fins 52 are arranged in Y-direction and attached to the
10 heat transfer members 51.
[0065] The electronic device 3 may include heat dissipaters 53 extending in Xdirection or the travel direction of the vehicle 100. The heat dissipaters 53 have the
same function as the headers 24a in the heat transfer members 22 in the electronic device
1. For example, the heat dissipaters 53 are pipes formed from a highly thermally
15 conductive material including metal such as iron or aluminum, and contain a coolant
therein. The coolant is a substance in vapor and liquid phases at ordinary temperature,
such as water.
[0066] Each heat transfer member 51 includes a base 51a, an extension 51b
attached to the base 51a, and a holder 51c attached to the extension 51b. The base 51a
20 extends in Y-direction, and is attached to the heat-receiving block 21 to be fully in
contact with the heat-receiving block 21. For example, the base 51a, the extension 51b,
and the holder 51c are pipes formed from a highly thermally conductive material
including metal such as iron or aluminum, and continuous with one another. Thus, the
base 51a, the extension 51b, and the holder 51c form a U-shaped heat pipe. The heat
25 pipe including the base 51a, the extension 51b, and the holder 51c contains a coolant
therein.
[0067] The bases 51a are received in grooves on the second main surface 21b of the
23
heat-receiving block 21 and attached to the heat-receiving block 21 by, for example,
bonding with an adhesive, or soldering. The bases 51a extend in the horizontal direction
for the vehicle 100 located horizontally. The bases 51a in contact with the heatreceiving block 21 extend in Y-direction. Thus, heat is efficiently transferred from the
5 heat-receiving block 21 to the coolant in the bases 51a. In Embodiment 3, each base
51a has one end continuous with the corresponding heat dissipater 53.
[0068] Each extension 51b has one end continuous with the other end of the
corresponding base 51a. The extensions 51b extend in Z-direction, or more specifically,
away from the heat-receiving block 21 to transfer heat in a direction away from the
10 second main surface 21b of the heat-receiving block 21.
[0069] Each holder 51c is continuous with the other end of the corresponding
extension 51b and extends away from the extension 51b. More specifically, the holders
51c extend along the second main surface 21b. In Embodiment 3, the holders 51c
extend in the horizontal direction for the vehicle 100 located horizontally. The fins 52
15 are attached to the holders 51c. The holders 51c hold the attached fins 52.
[0070] The electronic device 3 according to Embodiment 3 includes different heat
transfer members 51 including the extensions 51b with three different dimensions. The
heat transfer members 51 adjacent to one another in X-direction include the extensions
51b with different dimensions.
20 [0071] Each fin 52 is attached to the holders 51c in the heat transfer members 51
with the main surface substantially perpendicular to the horizontal direction for the
vehicle 100 located horizontally. In other words, the direction normal to the main
surface of each fin 52 is substantially aligned with the horizontal direction for the vehicle
100 located horizontally. The main surface substantially perpendicular to the horizontal
25 direction refers to the angle formed by the main surface and the horizontal plane being
within a range of 80 to 100 degrees inclusive. As described above, when the fins 52 are
attached to the heat transfer members 51, the main surface of each fin 52 is substantially
24
aligned with the vertical direction for the vehicle 100 located horizontally. To enhance
the performance of cooling electronic components when the vehicle 100 is traveling, the
main surfaces of the fins 52 are preferably parallel to X-axis. In other words, the
direction normal to the main surface of the vehicle 100 is preferably aligned with Y5 direction.
[0072] The heat dissipaters 53 are arranged in Y-direction. More specifically, the
heat dissipaters 53 are received in grooves on the second main surface 21b of the heatreceiving block 21 and attached to the heat-receiving block 21 by, for example, bonding
with an adhesive, or soldering. Each heat dissipater 53 receives multiple bases 51a.
10 [0073] Cooling of electronic components of the electronic device 3 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 bases 51a. Thus, the coolant evaporates. The evaporated coolant moves in the
extensions 51b in the positive Z-direction, and flows into the holders 51c. While
15 moving in the above manner, the coolant is cooled by transferring heat to air around the
heat transfer members 51 through the extensions 51b or the holders 51c and the fins 23,
and liquefies. The liquefied coolant returns to the bases 51a along the inner walls of the
holders 51c and the extensions 51b. As described above, the coolant circulates while
repeatedly evaporating and liquefying to transfer heat generated by at least one of the
20 switching elements SW1, SW2, and SW3 to air around the heat transfer members 51, and
cools the switching elements SW1, SW2, and SW3 generating heat.
[0074] As in Embodiment 1, when the vehicle 100 is traveling, the airflow flows
between the fins 52 to receive heat transferred from the fins 52 and cools the switching
elements SW1, SW2, and SW3.
25 [0075] When the vehicle 100 is stopped, no airflow occurs. As described above,
the fins 52 are attached to the holders 51c in the heat transfer members 51 with the main
surfaces perpendicular to the horizontal direction for the vehicle 100 located horizontally.
25
Thus, as indicated by arrows AR6 in FIG. 14, air inside the cover 30 receives heat
transferred from the fins 52 to be heated and moves in the positive Z-direction along the
fins 52. Air moving in the positive Z-direction flows out of the cover 30 through the
ventilation holes 30a. When air inside the cover 30 flows out through the ventilation
5 holes 30a, air outside the cover 30 flows into the cover 30 through the ventilation holes
30a as indicated by arrows AR7. In addition, air outside the cover 30 flows into the
cover 30 through the ventilation holes 30b not illustrated in FIG. 14. For simplicity,
FIG. 14 simply illustrates a part of airflow.
[0076] As described above, air flowing into the cover 30 receives heat transferred
10 from the fins 52 to be heated and moves vertically upward along the fins 52, and flows
out of the cover 30 through the ventilation holes 30a. The fins 52 attached to the heat
transfer members 51 with the main surfaces perpendicular to the horizontal direction for
the vehicle 100 located horizontally cause airflow moving vertically upward along the
fins 52. The switching elements SW1, SW2, and SW3 can thus be cooled through
15 natural convection in this manner also when the vehicle 100 is stopped.
[0077] As described above, the electronic device 3 according to Embodiment 3
includes the fins 52 attached to the heat transfer members 51 with the main surfaces
perpendicular to the horizontal direction for the vehicle 100 located horizontally. When
the vehicle 100 is stopped, air heated with heat transferred from the fins 52 moves
20 vertically upward along the fins 52. This causes airflow moving vertically upward
along the fins 52. Thus, the electronic device 3 can cool the electronic components
including the switching elements SW1, SW2, and SW3 through natural convection also
when the vehicle 100 is stopped.
[0078] The heat transfer members 51 including the bases 51a in contact with the
25 heat-receiving block 21 extending in Y-direction have higher efficiency of heat transfer
from the heat-receiving block 21 to the heat transfer members 51 than in Embodiments 1
and 2. Thus, the electronic device 3 has high cooling performance.
26
[0079] The electronic device 3 including the heat dissipaters 53 dissipates heat
transferred from the switching elements SW1, SW2, and SW3 through the heat-receiving
block 21 in X-direction. Thus, the electronic device 3 suppresses variations in
temperature of the heat-receiving block 21 in X-direction. Thus, the electronic device 3
5 can uniformly transfer heat to the heat transfer members 51 arranged in X-direction, and
enhance cooling performance.
[0080] Embodiment 4
The heat transfer members 51 and the fins 52 may have any shapes other than in
the examples in Embodiment 3. An electronic device 4 according to Embodiment 4
10 including heat transfer members 51 and fins 52 different from the heat transfer members
51 and the fins 52 in the electronic device 3 is described focusing on the differences from
the electronic device 3.
[0081] As illustrated in FIG. 15 and FIG. 16 that is a cross-sectional view taken
along line XVI-XVI as viewed in the direction indicated by the arrows in FIG. 15, each
15 heat transfer member 51 included in the electronic device 4 includes a base 51a, an
extension 51b, and a holder 51d. The holder 51d has one end attached to the extension
51b at a position vertically lower than the other end. Thus, the coolant liquefied in the
holder 51d more quickly reaches the extension 51b and the base 51a than the coolant in
Embodiment 3. The electronic device 4 thus circulates the coolant more quickly, and
20 has enhanced cooling performance.
[0082] The electronic device 4 according to Embodiment 4 includes different heat
transfer members 51 including the extensions 51b with four different dimensions. The
heat transfer members 51 adjacent to one another in X-direction include the extensions
51b with different dimensions.
25 [0083] As in Embodiment 3, each fin 52 is attached to the holders 51d in the heat
transfer members 51 with the main surface perpendicular to the horizontal direction for
the vehicle located horizontally. In Embodiment 4, at the center of the vehicle 100 in
27
the width direction, the fins 52 are arranged in a direction away from the second main
surface 21b of the heat-receiving block 21. In other words, the fins 52 are arranged in
Z-direction at the center of the vehicle 100 in Y-direction. More specifically, as
illustrated in FIG. 15, the fins 52 arranged in Y-direction and Z-direction are attached to
5 the heat transfer members 51 attached to the four heat dissipaters 53 located at the center
in Y-direction.
[0084] As in Embodiment 3, the coolant contained in the heat transfer members 51
circulates while repeatedly evaporating and liquefying to transfer heat generated by at
least one of the switching elements SW1, SW2, and SW3 to air around the heat transfer
10 members 51 and cools the switching elements SW1, SW2, and SW3 generating heat.
[0085] When the vehicle 100 is traveling, airflow flows between the fins 52 as in
Embodiment 1 to receive heat transferred from the fins 52 and cools the switching
elements SW1, SW2, and SW3. When the fins 52 are arranged in Z-direction, the
airflow also flows between the fins 52 adjacent to one another in Z-direction. Thus, the
15 fins 52 in the electronic device 4 have an area that comes in contact with the airflow
larger than the area in the electronic device according to Embodiment 3. Thus, the
electronic device 4 has enhanced cooling performance.
[0086] When the vehicle 100 is stopped, no airflow occurs. As in Embodiment 3,
air inside the cover 30 receives heat transferred from the fins 52 to be heated and moves
20 in the positive Z-direction along the fins 52. When the airflow flows in the positive Zdirection along the fins 52, a laminar boundary layer is formed near the fins 52. When
the airflow flows in the positive Z-direction, the velocity gradient at the surfaces of the
fins 52 decreases in the positive Z-direction, and the boundary layer may separate at the
position where the velocity gradient is 0, or more specifically, at the separation point.
25 The separation of the boundary layer causes airflow in a direction away from the fins 52,
and interrupts air flowing near the fins 52.
[0087] To suppress separation of the boundary layer, at least one of the fins 52
28
arranged in Z-direction is preferably displaced in Y-direction from the other fins 52
adjacent in Z-direction. More specifically, as illustrated in FIG. 15, the multiple fins 52
attached to the heat transfer members 51 attached to the two heat dissipaters 53 located at
the center in Y-direction may be located at different positions in Y-direction. When the
5 fins 52 are displaced in Y-direction, and air that has received heat transferred from the
fins 52 located downward in Z-direction moves in the positive Z-direction when the
vehicle 100 is stopped, the air comes in contact with another one of the fins 52 and causes
turbulence. The turbulence suppresses separation of the boundary layer near the fins 52
and allows air to flow near the fins 52. Thus, airflow occurs near the fins 52, and the
10 electronic device 4 has enhanced cooling performance.
[0088] As described above, the holder 51d included in each heat transfer member
51 included in the electronic device 4 according to Embodiment 4 has one end attached to
the extension 51b at a position vertically lower than the other end. Thus, the liquefied
coolant can quickly return to the base 51a through the extension 51b, and the electronic
15 device 4 has higher cooling performance than the electronic device 3.
[0089] When the fins 52 adjacent to one another in Z-direction are displaced from
one another in Y-direction, separation of the boundary layer near the fins 52 is
suppressed. Thus, the electronic device 4 has enhanced cooling performance.
[0090] The present disclosure is not limited to the above embodiments. For
20 example, the embodiments may be combined as appropriate.
[0091] The inverter 14 may supply power to any load, other than the airconditioning device 62, that operates when the vehicle 100 is stopped. In an example,
the inverter 14 can supply power to a lighting device or a door opening/closing device in
the vehicle 100.
25 [0092] The housing 20 may have any shape that can accommodate electronic
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 a housing 25 in an
29
electronic device 5 illustrated in FIG. 17 is inclined with respect to the horizontal plane
for the vehicle 100 located horizontally. More specifically, for the vehicle 100 located
horizontally, the surface with an opening 25a is inclined with respect to the horizontal
plane.
5 [0093] As described above, the second main surface 21b of the heat-receiving block
21 that covers the opening 25a inclined with respect to the horizontal plane is inclined
with respect to the horizontal plane for the vehicle 100 located horizontally. In this case,
the heat transfer members 22 may extend perpendicular to the second main surface 21b.
Thus, the heat transfer members 22 extend at an acute angle with respect to the horizontal
10 plane. More specifically, the branch pipes 24b are attached to the headers 24a so as to
extend in a direction perpendicular to the second main surface 21b.
[0094] In this case, the fins 23 may be attached to the heat transfer members 22
with the main surfaces perpendicular to the extension direction of the heat transfer
members 22. More specifically, the fins 23 may be attached to the branch pipes 24b
15 with the main surfaces perpendicular to the extension direction of the branch pipes 24b.
The heat transfer members 22 extend at an acute angle with respect to the horizontal
plane, and the main surfaces of the fins 23 are inclined with respect to the horizontal
plane. Thus, when the vehicle 100 is stopped, airflow vertically upward along the fins
23 occurs, and the electronic components including the switching elements SW1, SW2,
20 and SW3 can be cooled through natural convection.
[0095] The heat-receiving block 21 may be a plate having a curved surface
protruding away from the housing 20. In this case, the heat transfer members 22 may
extend at an acute angle with respect to the horizontal plane for the vehicle 100 located
horizontally.
25 [0096] The heat-receiving block 21 may be a single plate as described in the above
embodiments, or a combination of multiple plates. FIG. 18 illustrates an electronic
device 6 including multiple heat-receiving blocks 21. The electronic device 6 includes
30
the multiple heat-receiving blocks 21 and heat transfer members 51 attached to the heatreceiving blocks 21. Each heat transfer member 51 has the same structure as the heat
transfer member 51 in the electronic device 3 according to Embodiment 3. The heatreceiving blocks 21 in contact with each other are attached to the housing 20 to cover the
5 opening 20a. Each heat transfer member 51 is attached to the corresponding heatreceiving block 21. Thus, when any of the heat transfer members 51 has a defect, the
heat transfer member 51 with the defect can be simply replaced. This structure
facilitates maintenance and reduces maintenance costs.
[0097] Electronic components attached to the heat-receiving block 21 may be, for
10 example, any electronic components, other than the switching elements SW1, SW2, and
SW3, that are accommodated in the housing 20 or 25 such as a thyristor or a diode.
[0098] The heat transfer members 22 and 51 may not be heat pipes but may be
formed from any material that transfers heat in a direction away from the second main
surface 21b. For example, the heat transfer members 22 or 51 may be rod-like members
15 formed from a highly thermally conductive material including metal such as iron or
aluminum.
[0099] The heat transfer members 22 and 51 may be arranged in any manner other
than in the above examples to cool the electronic components through natural convection.
More specifically, in Embodiments 3 and 4, the holders 51c and 51d extend from the
20 extension 51b toward the center of the vehicle 100 in the width direction, but may extend
in another direction. In an example, as in one of the holders 51c in the heat transfer
members 51 in the electronic device 6 illustrated in FIG. 18 at the end in the width
direction of the vehicle 100, or in other words, the holder 51c in the heat transfer member
51 at the end in Y-direction, the holder 51c may extend from the extension 51b to the end
25 of the vehicle 100 in the width direction.
[0100] In another example, as in an electronic device 7 illustrated in FIG. 19, the
branch pipes 24b nearer the end of the vehicle 100 in Y-direction may extend away from
31
the second main surface 21b and extend toward the end of the vehicle 100 in Y-direction.
The branch pipes 24b nearer the center of the vehicle 100 in Y-direction may extend
away from the second main surface 21b and extend toward the center in Y-direction.
[0101] More specifically, in the electronic device 7, the two branch pipes 24b
5 nearer the end of the vehicle 100 in the negative Y-direction extend away from the
second main surface 21b and extend in the negative Y-direction. The two branch pipes
24b nearer the end of the vehicle 100 in the positive Y-direction extend away from the
second main surface 21b and extend in the positive Y-direction. Of the four branch
pipes 24b located at the center in Y-direction, the two branch pipes 24b located in the
10 negative Y-direction extend away from the second main surface 21b and extend in the
positive Y-direction. Of the four branch pipes 24b located at the center in Y-direction,
the two branch pipes 24b located in the positive Y-direction extend away from the second
main surface 21b and extend in the negative Y-direction.
[0102] As described above, each branch pipe 24b included in the electronic device
15 7 extends at an acute angle with respect to the second main surface 21b. As in
Embodiment 1, the fins 23 are attached to the branch pipes 24b with the main surfaces
perpendicular to the extension direction of the branch pipes 24b. Thus, the main
surfaces of the fins 23 are inclined with respect to the horizontal plane. Thus, airflow
vertically upward occurs to cool the electronic components including the switching
20 elements SW1, SW2, and SW3.
[0103] The headers 24a and the branch pipes 24b may have any shape, other than in
the above examples, that transfers heat in a direction away from the second main surface
21b. In an example, the header 24a and the branch pipe 24b may be integral with each
other to form a U-shaped or L-shaped heat pipe as the heat transfer member 22.
25 [0104] When taken perpendicular to the extension direction, each heat transfer
member 22 or 51 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
32
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 straight lines.
[0105] In an example, FIG. 20 illustrates an electronic device 8 including heat
5 transfer members 51 including holders 51c with elliptic cross sections. When the crosssectional areas are the same, the holders 51c with an elliptic cross section have a greater
surface area than the holders 51c with a circular cross section. Thus, the electronic
device 8 has higher cooling performance than the structure including the holders 51c with
a circular cross section independently of whether the vehicle 100 is traveling or stopped.
10 The electronic device 8 also produces the same effects when the heat transfer members
22 each have an elongated circular cross section taken perpendicular to the extension
direction.
[0106] To facilitate airflow in the positive Z-direction when the vehicle 100 is
stopped, as in the electronic device 8 illustrated in FIG. 21, an elongated circular cross
15 section of at least one of the holders 51c may have the longitudinal direction inclined with
respect to the horizontal plane, for the vehicle 100 located horizontally.
[0107] To flow the airflow to the vertical center of the fins 52 when the vehicle 100
is traveling, at least one of the holders 51c in the heat transfer members 51 to which the
same fins 52 are attached preferably has the longitudinal direction inclined with respect to
20 the horizontal plane for the vehicle 100 located horizontally. For example, in one of the
above holders 51c located vertically upward, one end nearer the center of the fins 52 in
the travel direction of the vehicle 100 is preferably located vertically lower than the other
end. In one of the above holders 51c located vertically downward, one end nearer the
center of the fins 52 in the travel direction of the vehicle 100 is preferably located
25 vertically higher than the other end.
[0108] The fins 23 having the main surfaces inclined with respect to the horizontal
plane may be attached to the heat transfer members 22 in any direction other than in the
33
above examples. For example, as in an electronic device 9 illustrated in FIG. 22, the
fins 23 may be attached to the branch pipes 24b extending perpendicular to the second
main surface 21b with one end 231, of two ends in Y-direction, nearer the center of the
vehicle 100 located vertically higher than the other end 232 of the two ends.
5 [0109] The fins 23 and 52 may be formed from the same material, or at least one of
the fins 23 or 52 may be formed from a material different from the material of the other
fins 23 or 52. When at least one of the fins 23 or 52 is formed from a material different
from the material of the other fins 23 or 52, the fins 23 or 52 has thermal conductivity
different from the thermal conductivity of the other fins 23 or 52. For example, the fins
10 23 located vertically upward preferably have higher thermal conductivity than the fins 23
located vertically downward. For example, the fins 23 located vertically upward may be
formed from copper, and the fins 23 located vertically downward may be formed from
aluminum.
[0110] Any number of fins 23 or 52 in any shape may be arranged in any manner
15 other than in the above examples. For example, the fins 23 or 52 may be plates with
curved surfaces. In another example, the fins 23 or 52 may have different shapes. In
another example, the fins 23 may be arranged in Z-direction. In this case, the fins 23
located vertically downward may be attached to all the heat transfer members 22. In
another example, the fins 52 may be arranged in X-direction and Y-direction. When the
20 fins 52 are arranged in X-direction, air receives heat transferred from the fins 52 to be
heated when the vehicle 100 is stopped, and can move vertically between the fins 52
adjacent to one another in X-direction. Thus, the electronic devices 3 and 4 have
enhanced cooling performance.
[0111] The cover 30 may have any shape that covers the heat transfer members 22
25 and the fins 23 or the heat transfer members 51 and the fins 52 and allows air to flow
inside. In an example, the cover 30 may have a vertically upper surface that is curved.
In another example, the cover 30 may have a vertically upper surface that is flat. The
34
cover 30 may have a shape that maximizes the inside space below the vehicle limit.
[0112] As in the electronic device 2, each of the electronic devices 3 to 9 may be
received in the container 100b that is a recess open vertically upward on the roof 100a of
the vehicle 100.
5 [0113] When other devices are located around each of the electronic devices 1 to 9,
the fins 23 located vertically upward can more easily come in contact with air flowing
from the outside than the fins 23 located vertically downward. Similarly, the fins 52
located vertically upward can more easily come in contact with air flowing from the
outside than the fins 52 located vertically downward. For example, when the fins 23
10 located vertically upward have higher thermal conductivity, and the fins 52 having the
vertically upper ends located higher than the vertically upper ends of the other fins 52
have higher thermal conductivity, the electronic devices 1 to 9 can have enhanced cooling
performance.
[0114] The electronic devices 1 to 9 may each be installable on a DC feeding
15 railway vehicle, rather than on an AC feeding railway vehicle. The electronic devices 1
to 9 may each be installable on any vehicle that creates airflow such as a trolley bus or a
streetcar, rather than the railway vehicle.
[0115] The foregoing describes some example embodiments for explanatory
purposes. Although the foregoing discussion has presented specific embodiments,
20 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, the
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
25 equivalents to which such claims are entitled.
This application claims the benefit of International Application No.
PCT/JP2021/022795, filed on June 16, 2021, the entire disclosure of which is
35
incorporated by reference herein.
Reference Signs List
[0116]
1, 2, 3, 4, 5, 6, 7, 8, 9 Electronic device
5 1a, 1b Input terminal
11 Transformer
12 Converter
13, 14 Inverter
15 Transformer
10 20, 25 Housing
20a, 25a Opening
21 Heat-receiving block
21a First main surface
21b Second main surface
15 22, 51 Heat transfer member
23, 41, 52 Fin
24a Header
24b Branch pipe
30 Cover
20 30a, 30b Ventilation hole
42 Heat pipe
51a Base
51b Extension
51c, 51d Holder
25 53 Heat dissipater
61 Motor
62 Air-conditioning device
36
100 Vehicle
100a Roof
100b Container
231, 232 End
5 AR1, AR2, AR3, AR4, AR5, AR6, AR7 Arrow
C1 Capacitor
D1, D2 Extension direction
SW1, SW2, SW3 Switching element
θ1, θ2 Angle

We Claim :
[Claim 1] An electronic device installable on a vehicle, the electronic device
comprising:
a heat-receiving block being heat conductive, the heat-receiving block having a
5 first main surface to which an electronic component is attached;
a heat transfer member attached to a second main surface of the heat-receiving
block, the second main surface being opposite to the first main surface, the heat transfer
member extending away from the second main surface to transfer heat transferred from
the electronic component through the heat-receiving block in a direction away from the
10 second main surface; and
one or more fins having main surfaces, the one or more fins being attached to the
heat transfer member with the main surfaces being inclined with respect to a horizontal
plane for the vehicle being located horizontally and configured to dissipate heat
transferred from the electronic component through the heat-receiving block and the heat
15 transfer member into ambient air.
[Claim 2] The electronic device according to claim 1, further comprising:
a housing accommodating the electronic component, the housing having an
opening in a vertically upper portion of the housing, the housing being installable on a
20 roof of the vehicle, wherein
the heat-receiving block is attached to the housing with the first main surface
covering the opening of the housing.
[Claim 3] The electronic device according to claim 1 or 2, wherein
25 the one or more fins include a plurality of fins arranged in a width direction of the
vehicle, and
each fin of the plurality of fins attached to the heat transfer member has, for the
38
vehicle being located horizontally, one of two ends in the width direction nearer a center
of the vehicle located vertically lower than the other of the two ends.
[Claim 4] The electronic device according to claim 1 or 2, wherein
5 the one or more fins include a plurality of fins arranged in four rows in a width
direction of the vehicle,
the plurality of fins attached to the heat transfer member include fins in two rows at
respective two ends in the width direction, and each of the fins in the two rows at the
respective two ends has, for the vehicle being located horizontally, one of two ends in the
10 width direction nearer a center of the vehicle located vertically higher than the other of
the two ends, and
the plurality of fins attached to the heat transfer member include fins in two rows at
the center of the vehicle in the width direction, and each of the fins in the two rows at the
center has, for the vehicle being located horizontally, one of two ends in the width
15 direction nearer the center of the vehicle vertically lower than the other of the two ends.
[Claim 5] The electronic device according to any one of claims 1 to 4, wherein
the one or more fins include a plurality of fins arranged in the width direction and
in the direction away from the second main surface.
20
[Claim 6] The electronic device according to claim 1 or 2, wherein
the one or more fins include a plurality of fins arranged in a width direction of the
vehicle, and
the plurality of fins attached to the heat transfer member have main surfaces
25 substantially perpendicular to a horizontal direction for the vehicle being located
horizontally.
39
[Claim 7] The electronic device according to claim 6, wherein
the plurality of fins are arranged in the width direction and in the direction away
from the second main surface, and
at least one fin of the plurality of fins arranged in the direction away from the
5 second main surface is displaced in the width direction from another of the plurality of
fins adjacent to the at least one fin in the direction away from the second main surface.
[Claim 8] The electronic device according to any one of claims 1 to 7, wherein
the heat transfer member extends vertically for the vehicle being located
10 horizontally.
[Claim 9] The electronic device according to any one of claims 1 to 7, wherein
the heat transfer member extends at an acute angle with respect to the horizontal
plane for the vehicle being located horizontally.
15
[Claim 10] The electronic device according to claim 9, wherein
the electronic device includes a plurality of the heat transfer members arranged in a
width direction of the vehicle, and
the plurality of heat transfer members extend away from the second main surface
20 and extend from a center toward an end in the width direction.
[Claim 11] The electronic device according to claim 9, wherein
the electronic device includes a plurality of the heat transfer members arranged in a
width direction of the vehicle,
25 the plurality of heat transfer members include a heat transfer member nearer an end
of the vehicle in the width direction extending away from the second main surface and
extending toward the end of the vehicle in the width direction, and
40
the plurality of heat transfer members include a heat transfer member nearer a
center of the vehicle in the width direction extending away from the second main surface
and extending toward the center of the vehicle in the width direction.
5 [Claim 12] The electronic device according to any one of claims 1 to 11, wherein
the second main surface of the heat-receiving block is inclined with respect to the
horizontal plane for the vehicle being located horizontally.
[Claim 13] The electronic device according to any one of claims 1 to 12, wherein
10 the heat transfer member includes
a base attached to the heat-receiving block,
an extension attached to the base and extending away from the heatreceiving block, and
a holder attached to the extension, the holder extending away from the
15 extension, the holder holding the one or more fins attached to the holder.
[Claim 14] The electronic device according to claim 13, wherein
the holder extends along the second main surface.
20 [Claim 15] The electronic device according to claim 13, wherein
the holder has one end attached to the extension at a position vertically lower than
the other end of the holder.
[Claim 16] The electronic device according to any one of claims 13 to 15,
25 wherein
the heat transfer member includes a plurality of the holders, and
the plurality of holders each have an elongated circular cross section when taken
41
perpendicular to an extension direction of the holder, and the elongated circular cross
section of at least one of the plurality of holders has a longitudinal direction inclined with
respect to the horizontal plane for the vehicle being located horizontally.
5 [Claim 17] The electronic device according to any one of claims 1 to 16, wherein
the electronic component receives power and generates heat independently of
whether the vehicle is traveling.
[Claim 18] The electronic device according to any one of claims 1 to 17, wherein
10 the heat transfer member includes a heat pipe containing a coolant therein.
[Claim 19] The electronic device according to claim 2, wherein
the housing is accommodated in a container being a recess open vertically upward
on the roof of the vehicle.
15
[Claim 20] The electronic device according to claim 19, wherein
for the vehicle being located horizontally, the heat transfer member and the one or
more fins each have a vertically upper end located higher than a vertically upper end of
the recess.