FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
BREATHING DEVICE AND ELECTRIC POWER STEERING 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 invention relates to a breathing device
configured to provide a breathing action, and to 5 an electric power
steering device.
Background Art
[0002] Hitherto, some devices such as electric power steering
10 devices and motor generators including a rotating machine and a
control unit integrated with each other are mounted to a vehicle
in the vicinity of a rack shaft outside a cabin. In such devices,
in order to secure waterproofness, methods such as application of
a sealing material and installation of an O-ring are employed not
15 only as the waterproof structure for the rotating machine and the
control unit but also as the waterproof structure for connection
surfaces of the rotating machine and the control unit.
[0003] Incidentally, when such a device has the sealed
structure for complete waterproofness, the air inside the device
20 expands due to generation of heat from the rotating machine or the
control unit, and the air inside the device shrinks when the device
is cooled thereafter. Such a load deteriorates the waterproof
structure, and hence the structure for promoting a breathing action
is required.
25 [0004] Therefore, as a related art, there has been known an
3
electric power steering device which is configured to prevent
clogging of a breathing hole and a filter to improve ventilation
efficiency of a case, and is configured to reduce a pressure
difference between an outside and an inside of the case when the
temperature and pressure in the case rapidly 5 increase (see, for
example, Patent Literature 1).
Citation List
Patent Literature
10 [0005] [PTL 1] JP 2005-132165 A
Summary of Invention
Technical Problem
[0006] According to the above-mentioned technology disclosed
15 in Patent Literature 1, a case forming a breather includes a
breathing hole provided with a filter. This filter is
water-repellent, and thus is impermeable to water but permeable
to air. Therefore, the filter provides a certain level of
waterproofness against water spray such as rain. However, there
20 is such a problem that the filter alone cannot maintain sufficient
waterproofness unless a way of use is devised in an environment
in which a pressure difference equal to or larger than that expected
according to a standard specification occurs due to, for example,
a temperature difference equal to or larger than a difference
25 determined in advance.
4
[0007] The present invention has been made to solve such a
problem, and has an object to provide a breathing device capable
of improving waterproofness, and an electric power steering device.
Solution 5 to Problem
[0008] In order to achieve the above-mentioned object, a
breathing device according to one embodiment of the present
invention includes a ventilator, which is provided to an electric
power steering device, and is arranged so as to protrude from an
10 inside of the electric power steering device to an outside of the
electric power steering device, the ventilator being configured
to provide a breathing action through ventilation between the inside
and the outside, the electric power steering device being mounted
to a vehicle and including a rotating machine and a control unit
15 configured to drive the rotating machine, which are integrated with
each other so as to have waterproof structure, wherein the
ventilator protrudes in a horizontal direction or upward with
respect to the horizontal direction.
20 Advantageous Effects of Invention
[0009] According to the present invention, through employment
of the above-mentioned configuration, the breathing device can
improve the waterproofness.
25
5
Brief Description of Drawings
[0010] FIG. 1 is a schematic view for illustrating a main part
of a vehicle to which an electric power steering device according
to a first embodiment of the present invention is mounted.
FIG. 2 is a partially transparent perspective 5 view for
illustrating the basic structure of the electric power steering
device illustrated in FIG. 1.
FIG. 3 is an end view for illustrating the electric power
steering device illustrated in FIG. 2 as seen from a control unit
10 side.
FIG. 4 is a partially cutaway side view for illustrating the
electric power steering device illustrated in FIG. 2, with vehicle
members, as seen from a side-surface side of the control unit.
FIG. 5 is a side sectional view for illustrating the control
15 unit side of a main part of the electric power steering device
according to a second embodiment of the present invention.
FIG. 6 is a partially cutaway side sectional view for
illustrating the basic structure of the electric power steering
device according to a third embodiment of the present invention,
20 with an inside thereof being exposed.
FIG. 7 is a plan view for illustrating a connector provided
on an end surface of the control unit of the main part of the electric
power steering device according to a fourth embodiment of the
present invention.
25 FIG. 8 is a side sectional view for illustrating a part of
6
the connector illustrated in FIG. 7 taken along the line C-C.
Description of Embodiments
[0011] Now, with reference to drawings, a detailed description
is given of a breathing device and an electric power 5 steering device
according to the present invention with several embodiments.
[0012] First Embodiment
FIG. 1 is a schematic view for illustrating a main part of
a vehicle to which an electric power steering device 10 according
10 to a first embodiment of the present invention is mounted.
[0013] Referring to FIG. 1, the main part of the vehicle
includes a steering wheel 1, a rack shaft 2, a torque sensor 3,
a pinion 4, tires 5, and the electric power steering device 10.
The torque sensor 3 among these components is mounted to a column
15 extending from the steering wheel 1, and is configured to detect
a steering torque by a driver. The electric power steering device
10 has the waterproof structure formed through integration of a
motor 7, which is a rotating machine, and a control unit 6, and
is configured to mesh with a gear 8 along a rack shaft 2.
20 [0014] The electric power steering device 10 is mounted at a
position closer to the ground than the rack shaft 2 along the rack
shaft 2. Compared with the case in which the electric power steering
device 10 is mounted to a portion above the rack shaft 2 as in the
case of the torque sensor 3, when the electric power steering device
25 10 is mounted at the position close to the ground, higher
7
waterproofness are essentially required in specifications.
[0015] FIG. 2 is a partially transparent perspective view for
illustrating the basic structure of the electric power steering
device 10.
[0016] Referring to FIG. 2, in the electric 5 power steering
device 10, the motor 7 incorporates a stator, windings, a rotor,
and the like in a motor housing 7a, as is publicly known. A distal
end of an output shaft 11 protruding from an end surface meshes
with the gear 8 of the vehicle. The motor housing 7a is made of
10 metal, and has a bottom on a right side of FIG. 2 and an opening
on a left side. Therefore, the entry of water from a side surface
of the motor 7 illustrated in FIG. 2 can completely be blocked.
[0017] When the motor 7 is mounted to the gear 8 of the vehicle,
motor mounting portions 13 provided at four positions and the gear
15 8 are fixed to each other by fastening with screws. The motor
mounting portions 13 may be provided at three positions depending
on a mounting direction. In this case, the waterproofness between
the motor 7 and the gear 8 is secured by fitting an O-ring to an
O-ring groove 14 formed on a radially inner side of the motor
20 mounting portions 13.
[0018] A bearing 12 is mounted at a base portion of the output
shaft 11 in a surface of the motor mounting portions 13 on a radially
inner side of the O-ring groove 14. The bearing 12 may have the
non-waterproof structure or the waterproof structure. In the case
25 of the waterproof structure, for example, it is only required that
8
the O-ring be mounted on an outer periphery and that a seal member
obtained by affixing rubber to an outer periphery of a metal plate
be mounted to each of an inner ring and an outer ring. With such
structure, a breathing passage is eliminated between an inside and
an outside of this bearing 12. Moreover, when 5 the waterproof
structure is not employed in the bearing 12, the waterproof
performance may be secured through installation of an oil seal on
the gear side of the bearing 12.
[0019] Meanwhile, the control unit 6 integrally coupled to the
10 motor housing 7a incorporates, for example, a circuit network and
the like in a case 6a made of an insulation resin material. The
motor housing 7a and the case 6a are mounted to each other so as
to form the waterproof structure by fastening with screws at three
positions of mounting portions 16, and further, for example,
15 applying a gasket or a sealing material to inner walls on contact
surfaces of the motor housing 7a and the case 6a. A power supply
connector 20 and a signal connector 21 including a torque sensor
3 are formed integrally with the case 6a in a rear end portion of
the control unit 6.
20 [0020] When the electric power steering device 10 is driven,
both of the motor 7 and the control unit 6, which serves to control
the drive of the motor 7, generate heat. Particularly, in order
to radiate the heat generated inside the control unit 6 when the
motor 7 is driven, there is provided the structure in which a heat
25 radiation member is arranged so as to transfer the heat also to
9
the motor 7 and the motor components.
[0021] Incidentally, most of structures of the motor 7 itself
are made of metal, and the entire motor 7 thus also serves as a
heat radiation member. When the motor 7 is driven, the air expands
due to the generation of heat in the electric power 5 steering device
10. In contrast, when the electric power steering device 10 is
cooled while driving of the vehicle is stopped, the air becomes
negative in pressure and thus shrinks. Therefore, the structure
configured to provide a breathing action is required for the
10 electric power steering device 10.
[0022] For that purpose, in the electric power steering device
10, a breathing device 22 is arranged at a position close to the
power supply connector 20 and the signal connector 21 on an end
surface of the control unit 6 on the side opposite to the output
15 shaft 11 of the motor 7. The breathing device 22 includes a
ventilator which protrudes from an inside of the electric power
steering device 10 to an outside of the electric power steering
device 10, to thereby be capable of ventilation. The breathing
device 22 is configured to provide the breathing action through
20 ventilation between the inside and the outside of the electric power
steering device 10. It is only required that the ventilator
protrude basically in a horizontal direction or upward with respect
to the horizontal direction, and may be considered as a tubular
chimney in terms of functionality.
25 [0023] In the arrangement of the breathing device 22, when the
10
breathing device 22 is mounted to a lowest portion of the vehicle,
there is a risk in that the entire electric power steering device
10 may be submerged due to, for example, traveling in a puddle.
In consideration of this point, it is preferred that the breathing
device 22 be arranged at a position as high as possible 5 on the end
surface of the control unit 6.
[0024] It is preferred that the breathing device 22 include
a water-repellent filter 22a mounted on an inner side of the electric
power steering device 10. The water-repellant filter 22a can
10 prevent the entry of water into the control unit 6 when the water
enters the breathing device 22.
[0025] FIG. 3 is an end view for illustrating the electric
power steering device 10 as seen from the control unit 6 side. FIG.
4 is a partially cutaway side view for illustrating the electric
15 power steering device 10, with vehicle members, as seen from a
side-surface side of the control unit 6.
[0026] Referring to FIG. 3, the breathing device 22 is arranged
at a substantially middle position between the power supply
connector 20 and the signal connector 21 on the end surface of the
20 electric power steering device 10 on the control unit 6 side.
Moreover, a large-component accommodation portion 23 configured
to incorporate large components such as a noise filter and a
capacitor, which are difficult to be incorporated in the control
unit 6, is provided in a diagonal direction of the breathing device
25 22.
11
[0027] The power supply connector 20 includes two terminals
on a plus side and a minus side. Sectional areas of the terminals
are set to be large so that a large current for driving the motor
7 can be supplied. In contrast, in the signal connector 21, a large
number of small terminals are arranged so as to be 5 used for inputting
information on the vehicle side such as that from the torque sensor
3 and vehicle speed and outputting transmission signals from the
control unit 6. A ventilation hole is formed at the center of the
breathing device 22 so as to be capable of ventilation.
10 [0028] Referring to FIG. 4, in the electric power steering
device 10, moreover, a vehicle-side connector 20a is connected to
the power supply connector 20, and a harness 20b is further connected
to the vehicle-side connector 20a. A vehicle-side connector 21a
is connected also to the signal connector 21, and a harness 21b,
15 which is a signal line, is further connected to the vehicle-side
connector 21a. All of these connectors have waterproof
specifications.
[0029] The mounting position of the electric power steering
device 10 to the vehicle is on the lowest layer, and hence all of
20 the vehicle side connectors 20a and 21a and the harnesses 20b and
21b are connected so as to extend upward. Incidentally, the torque
sensor 3 is illustrated in FIG. 1, and other components such as
a battery and a vehicle speed sensor are arranged above the rack
shaft 2. Therefore, the harnesses 20b and 21b extend upward.
25 [0030] In the breathing device 22, when the water-repellant
12
filter 22a is to be mounted, it is only required that the
water-repellant filter 22a be mounted so as to cover the hole formed
in a part of an inner peripheral surface of the case 6a. Moreover,
a ventilator 22b of the breathing device 22 extends so as to protrude
on the outer side of the case 6a. The structure 5 that includes the
ventilator 22b as a part and is further extended can be employed.
For example, a pipe, a tube 22c, or the like can be added to a distal
end portion of the ventilator 22b. It is preferred that, as
illustrated in FIG. 4, the pipe, the tube 22c, or the like have
10 a shape bent upward.
[0031] The breathing device 22 having the extended structure
including the ventilator 22b may be arranged in a lower portion
of the end surface of the control unit 6. Moreover, for example,
the ventilator 22b and the tube 22c may be extended along the
15 vehicle-side harnesses 20b and 21b, or may be fixed together with
the harnesses 20b and 21b. Further, when a distal end portion of
the tube 22c is extended to an inside of the vehicle body in which
there is not a fear of exposure to water, complete waterproofness
is achieved. When the tube 22c can be extended to the inside of
20 the cabin, the water-repellant filter 22a of the breathing device
22 is not required.
[0032] As a ventilation passage from the breathing device 22
to the inside the electric power steering device 10, in a case of
the motor 7, for example, a gap defined between the stator and the
25 rotor or a gap defined between an outer layer of the stator and
13
an inner surface of the motor housing 7a may be used. Moreover,
a control CPU, various electric lines, ICs, a drive circuit for
the motor windings, and the like are mounted to substrates, relay
members, and heatsinks inside the control unit 6. Many spaces are
defined between the substrates, the relay members, 5 the heatsinks,
and the like, and the case 6a, and an infinite number of ventilation
passages thus is present. Therefore, as the ventilation passages
inside the control unit 6 and the motor 7, the spaces defined by
respective portions can be used.
10 [0033] As described above, the electric power steering device
according to the first embodiment has the configuration in which
the breathing device is arranged on the outer surface of the case
of the control unit. Therefore, while the breathing action of the
breathing device effectively functions, the waterproofness can be
15 secured even in an environment in which a pressure difference equal
to or larger than that expected according to a standard
specification occurs. Moreover, the breathing action of the
breathing device can prevent deterioration of the waterproof
performance of the electric power steering device.
20 [0034] Further, in the electric power steering device
according to the first embodiment, the waterproof structure can
be provided by extending the ventilator of the breathing device,
and arranging the extension along the harnesses or fixing the
extension together with the harnesses. With this configuration,
25 even when the electric power steering device is submerged, the
14
breathing action of the breathing device can be secured. Moreover,
when the ventilator of the breathing device is extended, the
structure to achieve complete waterproofness of the ventilator is
not required. Further, the ventilation passage can be secured
through use of a path having suitable shape inside 5 the electric
power steering device.
[0035] Second Embodiment
FIG. 5 is a side sectional view for illustrating the control
unit 6 side of a main part of the electric power steering device
10 according to a second embodiment of the present invention. In the
second embodiment, components of the electric power steering device
having the same configuration are denoted by the same reference
numerals as those in the first embodiment. Thus, description of
those components is omitted, and description is mainly given of
15 different configurations.
[0036] In the electric power steering device according to the
second embodiment, a breathing device 24 is provided on a side
surface of the case 6a, which has a cylindrical case, of the control
unit 6. In this configuration, the breathing device 24 is provided
20 separately from the case 6a. Therefore, a mounting hole 6b for
mounting the breathing device 24 is formed in the case 6a.
[0037] A water-repellant filter 24a is mounted to a lower end
portion of the breathing device 24 located inside the control unit
6. The breathing device 24 includes a ventilator 24b extending
25 upward. When the breathing device 24 is inserted into a mounting
15
hole 6b of the case 6a to be mounted, an O-ring 24c is arranged
between an outer peripheral wall of the case 6a and a lower portion
of the breathing device 24 in order to secure waterproofness between
the case 6a and the breathing device 24. Through the insertion of
the breathing device 24 into the mounting hole 5 6b to be mounted,
the O-ring 24c is compressed, thereby securing the waterproofness.
A waterproof adhesive or a sealing material may be used in place
of the O-ring 24c.
[0038] The breathing device 24 according to the second
10 embodiment is provided in an upper portion of the side surface of
the control unit 6, and the exposure to water of the breathing device
24 thus is less liable to occur. Therefore, the water-repellant
filter 24a is not always required. Moreover, in FIG. 5,
illustration is given of an example case in which a diameter of
15 the ventilation passage of the ventilator 24b is constant. However,
the ventilation passage of the ventilator 24b may be formed so that
the diameter thereof increases as the position approaches the
water-repellant filter 24a.
[0039] In the breathing device 24, in consideration of a
20 resistance in the breathing action, the water-repellant filter 24a
has the highest resistance, and a portion causing a resistance is
not present in the ventilation passage in the ventilator 24b.
Therefore, even when the diameter of the ventilation passage is
smaller than the hole diameter at the mounting position of the
25 water-repellant filter 24a, the effect of the breathing action is
16
not reduced.
[0040] In the case of the electric power steering device
according to the second embodiment, description is given of the
configuration in which the breathing device 24 is mounted to the
upper portion of the side surface of the control 5 unit 6. However,
in place of this configuration, the breathing device 24 may be
mounted to an upper portion of the side surface of the motor housing
7a illustrated in FIG. 2. The motor housing 7a incorporates the
stator, the motor windings, and the like, and it is thus required
10 to mount the breathing device 24 at a position without interference
with these components.
[0041] Incidentally, in a case in which the generation of heat
on the motor 7 side is large due to the presence of the motor windings
and the like, when the breathing device 24 is mounted to the motor
15 housing 7a, the pressure difference between the inside and the
outside of the electric power steering device 10 can be promptly
eliminated. Moreover, in the case in which the generation of heat
on the control unit 6 side is large due to the presence of the CPU
and the like, when the breathing device 24 is mounted to the case
20 6a, the pressure difference between the inside and the outside of
the electric power steering device 10 can be promptly eliminated.
[0042] In the second embodiment, the ventilation passage at
the center of the ventilator 24b extends upward in the form of a
chimney also in the breathing device 24 provided separately of the
25 case 6a. With this configuration, the ventilator 24b can be used
17
as a ventilation passage, and the ventilation in the control unit
6 is thus particularly achieved. As a result, a change in pressure
inside the electric power steering device can be reduced through
use of the breathing action of the breathing device 24, and
deterioration of a waterproof function of other 5 portions can also
be prevented.
[0043] It is preferred that the breathing device 24 according
to the second embodiment be arranged in a position as high as
possible in the electric power steering device. Moreover, there
10 is given the configuration in which the water-repellant filter 24a
is mounted to the lower portion of the ventilator 24b, but the
water-repellant filter 24a may be mounted to an upper portion of
the ventilator 24b.
[0044] Third Embodiment
15 FIG. 6 is a partially cutaway side sectional view for
illustrating the basic structure of the electric power steering
device according to a third embodiment of the present invention,
with an inside thereof being exposed. In the third embodiment,
components of the electric power steering device having the same
20 configuration are denoted by the same reference numerals as those
in the first and second embodiments. Thus, description of those
components is omitted, and description is mainly given of different
configurations.
[0045] In the electric power steering device according to the
25 third embodiment, the breathing device 24 is provided on an end
18
surface of the motor housing 7a of the motor 7. Moreover, the
electric power steering device according to the third embodiment
is of a type in which the control unit 6 is arranged on the output
side of the output shaft 11 of the motor 7.
[0046] In the motor 7, as in the related-art 5 type, a rotor 72,
a stator 71, and windings 73 are arranged inside the motor housing
7a from the output shaft 11 as a central axis toward an outer side
in a radial direction. End portions of the windings 73 are connected
by an annular circuit 74, and are further extended to a unit inner
10 portion 6c of the control unit 6. Bearings 12a and 12b are
respectively interposed on both of end sides of the output shaft
11. The output shaft 11 can freely be rotated through use of these
bearings 12a and 12b.
[0047] The control unit 6 includes a housing 6d made of, for
15 example, aluminum, so as to also serve as a heat radiation member.
A relay member 63, a control substrate 60, power elements 62, and
the like are arranged in the unit inner portion 6c. The relay member
63 is configured to mount wires and components. The control
substrate 60 includes electronic components such as the CPU 61
20 mounted thereon. The power elements 62 are configured to supply
currents to the motor windings 73. Moreover, the power supply
connector 20 and the signal connector 21 for the electrical
connection to the vehicle are arranged so as to protrude from the
side surface of the control unit 6.
25 [0048] As described above, in the integrated structure of the
19
motor 7 and the control unit 6 arranged on the output side of the
output shaft 11, in some cases, a hole is formed in an end surface
of a rear end portion of the motor 7 in order to arrange an axial
center of the output shaft 11 with high accuracy.
[0049] In view of such cases, in the electric 5 power steering
device according to the third embodiment, the breathing device 24
is arranged so as to close this hole. The breathing device 24 itself
has basically the same structure as that described in the second
embodiment. That is, the breathing device 24 includes the
10 water-repellant filter 24a, the O-ring 24c, and the ventilator 24b.
However, in the breathing device 24 according to the third
embodiment, an extended ventilator 24e bent upward is provided in
a distal end portion of the ventilator 24b. In the drawing of FIG.
6, the extended ventilator 24e is illustrated in a state in which
15 the extended ventilator 24e is bent toward the left side, but this
left side corresponds to the upper side in a state in which the
motor 7 is actually installed.
[0050] When the electric power steering device according to
the third embodiment is arranged below the rack shaft 2 illustrated
20 in FIG. 1, it is only required that the extended ventilator 24e
of the breathing device 24 be extended to a position close to the
rack shaft 2. In this case, even when the electric power steering
device is submerged, the breathing action of the breathing device
24 can be secured.
25 [0051] Conversely, when the electric power steering device
20
according to the third embodiment is arranged above the rack shaft
2, the extended ventilator 24e of the breathing device 24 may be
extended downward. When the extended ventilator 24e of the
breathing device 24 is extended downward, there is an advantage
in that entry of dust or foreign matters into 5 the ventilator 24b
is significantly rare. Further, ventilation performance can also
be improved through elimination of the water-repellant filter 24a
depending on a total length of the ventilator 24b and the extended
ventilator 24e.
10 [0052] In the third embodiment, there is given the structure
in which the hole formed in the end surface of the rear end portion
of the motor 7 is used to mount the breathing device 24. The
direction of the extended ventilator 24e of the breathing device
24 can be changed in accordance with the arrangement, the waterproof
15 performance, and the like of the electric power steering device.
Even in such a case, the breathing action of the breathing device
24 can be secured.
[0053] Fourth Embodiment
FIG. 7 is a plan view for illustrating a power supply connector
20 20A provided on an end surface of the control unit 6 in a fourth
embodiment of the present invention. Moreover, FIG. 8 is a side
sectional view for illustrating a part of the power supply connector
20A illustrated in FIG. 7 taken along the line C-C. In the fourth
embodiment, components of the electric power steering device having
25 the same configuration are denoted by the same reference numerals
21
as those in the first to third embodiments. Thus, description of
those components is omitted, and description is mainly given of
different configurations.
[0054] In the electric power steering device according to the
fourth embodiment, a ventilator is formed of 5 gaps 20f defined
between terminals 20c and a connector housing 20e in the power supply
connector 20A on the end surface of the control unit 6 on the side
opposite to the output shaft 11 of the motor 7. That is, this
ventilator functions as the breathing device.
10 [0055] Specifically, the power supply connector 20A
illustrated in FIG. 7 has the structure in which two terminals 20c
are arranged side by side. Referring to FIG. 7, gaps 20f each having
a width narrower than that of the terminal 20c are formed in a
widthwise direction of the terminals 20c. Further, referring to
15 FIG. 8, the gaps 20f having the same width are formed on both sides
of each of the terminal 20c.
[0056] In the power supply connector 20A, the terminals 20c
are made of copper, and the connector housing 20e is made of a plastic
resin. The connector housing 20e serves to support the terminals
20 20c. Therefore, contact portions between the terminals 20c and the
connector housing 20e have certain amounts of area and length.
Therefore, the length of the gaps 20f is long along the terminals
20c, and the gaps 20f can be considered as tubular chimneys.
[0057] For example, as illustrated in FIG. 8, the width of the
25 terminal 20c is represented by L, and the half width of the gap
22
20f is represented by α/2. The gaps 20f serve as holes for the
breathing. The width of the gap 20f is determined in accordance
with the ambient temperature and linear expansion coefficients of
respective portions.
[0058] Thus, the following representative values 5 are given as
specific examples.
Linear expansion coefficient Ec of the copper of the terminals
20c: 16.5 ppm
Linear expansion coefficient Ep of the resin of the connector
10 housing 20e: 100 ppm (polybutylene terephthalate (PBT))
Ambient temperature: -40°C to normal temperature of 25°C
Width L of the terminals 20c: 8 mm
Width of the gaps 20f: α (mm)
[0059] In consideration of the fact that the width of the gaps
15 20f decreases as the terminals 20c and the connector housing 20e
shrink, it is required to determine the width α of the gaps 20f
at the normal temperature. For the determination of the width α,
the following relational expression (1) is considered.
(L+α)(1+Ep*(-40-25))-L*(1+Ec*(-40-25))
20 =65*L*(Ec-Ep)+(1-65Ep)*α
[0060] In consideration of path resistances and volumes of the
control unit 6 and the motor 7, in order to secure a gap 20f=0.1
mm even at low temperature, it is required to satisfy relational
expression (1)>0.1 as given by the following.
25 α>65*L*(Ec-Ep)/(1-65*Ep)>0.1
23
α>0.095
Thus, when approximately 0.1 mm is secured as the width α of
the gap 20f, the chimneys are not blocked in the usage environment,
and the breathing action given by the ventilator of the breathing
device 5 can be secured.
[0061] In the fourth embodiment, the gaps 20f configured to
promote the breathing action are provided in the vicinities of the
terminals 20c of the power supply connector 20A, and the area of
the gaps 20f can be determined in consideration of a usage
10 environment temperature of the electric power steering device. As
a result, the gaps 20f are used as the chimneys, to thereby be able
to secure the breathing action as the breathing device without
providing a ventilator as the breathing device separately of the
case 6a.
15 [0062] The ventilators of the breathing devices described in
the respective embodiments may have any suitable shape, which
includes the cases in which the ventilators are extended, as long
as the waterproofness of the distal end portions is secured.
20 Reference Signs List
[0063] 1 steering wheel, 2 rack shaft, 3 torque sensor, 4
pinion, 5 tire, 6 control unit, 6a case, 6b mounting hole, 6c unit
inner portion, 6d housing, 7 motor (rotating machine), 7a motor
housing, 10 electric power steering device, 11 output shaft, 12,
25 12a, 12b bearing, 13 motor mounting portion, 14 O-ring groove, 16
24
mounting portion, 20, 20A power supply connector, 20a, 21a
vehicle-side connector, 20b, 21b harness, 20c terminal, 20e
connector housing, 20f gap, 21 signal connector, 22, 24 breathing
device, 22a, 24a water-repellant filter, 22b, 24b ventilator, 22c
tube, 24c O-ring, 24e extended 5 ventilator
25
We claim:
[Claim 1] A breathing device, comprising a ventilator, which is
provided to an electric power steering device, and is arranged so
as to protrude from an inside of the electric power 5 steering device
to an outside of the electric power steering device, the ventilator
being configured to provide a breathing action through ventilation
between the inside and the outside, the electric power steering
device being mounted to a vehicle and including a rotating machine
10 and a control unit configured to drive the rotating machine, which
are integrated with each other so as to have waterproof structure,
wherein the ventilator protrudes in a horizontal direction
or upward with respect to the horizontal direction.
15 [Claim 2] The breathing device according to claim 1, wherein the
ventilator is arranged on an end surface of the control unit provided
with a connector on a side opposite to an output shaft of the rotating
machine.
20 [Claim 3] The breathing device according to claim 1, wherein the
ventilator is arranged on a side surface of a case of the control
unit.
[Claim 4] The breathing device according to claim 1, wherein the
25 ventilator is arranged on an end surface of a housing of the rotating
26
machine.
[Claim 5] The breathing device according to claim 1, wherein the
ventilator is formed of a gap defined between a terminal and a
connector housing in a connector provided on an 5 end surface of the
control unit on a side opposite to an output shaft of the rotating
machine.
[Claim 6] The breathing device according to claim 2, wherein the
10 ventilator is integrated with a case of the control unit at a
position close to the connector.
[Claim 7] The breathing device according to claim 3 or 4, wherein
the ventilator is mounted to the case of the control unit or the
15 housing of the rotating machine separately of the case or the
housing.
[Claim 8] The breathing device according to any one of claims 2
to 7, wherein the ventilator is arranged along a harness on the
20 vehicle side, or is fixed together with the harness, and a distal
end portion of the ventilator is arranged so as to be extended.
[Claim 9] The breathing device according to any one of claims 2
to 8, wherein a distal end portion of the ventilator on the vehicle
25 side is extended to a vicinity of a cabin.
27
[Claim 10] An electric power steering device, comprising:
the breathing device of any one of claims 1 to 9;
the rotating machine; and
5 the control unit.