FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
ELECTRIC POWER STEERING APPARATUS;
MITSUBISHI ELECTRIC CORPORATION, A CORPORATION ORGANISED AND EXISTING UNDER
THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3, MARUNOUCHI 2-CHOME, CHIYODA-KU,
TOKYO 1008310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND
THE MANNER IN WHICH IT IS TO BE PERFORMED.
2
DESCRIPTION
Technical Field
[0001]
The present disclosure relates to an electric 5 power steering
apparatus in which a motor and a control unit are integrated with
each other.
Background Art
10 [0002]
As is well known, an electric power steering apparatus is
configured in such a way that auxiliary torque corresponding to
steering torque exerted on a steering shaft by a driver of a vehicle
is generated by a motor so that steering by the driver is assisted;
15 however, in an electric power steering apparatus in which a motor
and a control unit for controlling the motor are integrated with each
other, in consideration of a case where the electric power steering
apparatus is installed in the vicinity of a rack axel outside the
vehicle interior, there are required not only waterproofing measures
20 for the motor itself and the control unit itself but also waterproofing
measures for the coupling portion between the motor and the control
unit. To date, as waterproofing measures for the coupling portion
between the motor and the control unit, there have been taken measures
in which, for example, a seal is applied to or an O-ring is mounted
25 on the coupling portion.
3
[0003]
In an electric power steering apparatus disclosed in Patent
Document 1, a motor and a control unit are integrated with each other
and, as waterproofing measures for the space between the power
steering apparatus and a gear housing that are provided 5 at the vehicle
side, there is adopted a structure in which a ring-shaped sealing
member passing through the outside of an electric connection portion
of the motor is mounted between the motor and a motor mounting portion
of the gear housing. The conventional electric power steering
10 apparatus disclosed in Patent Document 1 make it possible to secure
the waterproof property and the dust resistance in the connection
portion between the motor and the gear housing and to secure the
waterproof property also in the electric connection portion of the
motor.
15 [0004]
Meanwhile, in the case of an electric power steering apparatus
having a watertight structure in which a motor and a control unit
are completely waterproof, when due to heat generation in the motor
or the control unit, the temperature of air inside the electric power
20 steering apparatus rises, the pressure inside the electric power
steering apparatus may become higher than that of the outer air; in
contrast, when for example, due to stoppage of the electric power
steering apparatus, the temperature of air inside the electric power
steering apparatus falls, the pressure inside the electric power
25 steering apparatus may become lower than that of the outer air, i.e.,
4
a so-called negative pressure may occur. When the pressure change
in the inside of the electric power steering apparatus is repeated,
the waterproofing member of the electric power steering apparatus
is deteriorated; therefore, there exists a probability that due to
a pressure difference between the inside of 5 the electric power
steering apparatus and the outside thereof, water intrudes into the
inside of the electric power steering apparatus.
[0005]
Patent Document 2 discloses an electric power steering
10 apparatus having a completely waterproof and watertight structure;
it is proposed that in order to prevent a pressure change in air inside
the electric power steering apparatus from deteriorating a
waterproofing member, there is provided a respiratory hole for making
the inside and the outside of the electric power steering apparatus
15 communicate with each other, and a filter is inserted into the
respiratory hole. The conventional electric power steering
apparatus disclosed in Patent Document 2 makes it possible that even
when a self-heating member causes the temperature inside the electric
power steering apparatus to rise, the air inlet reduces or relaxes
20 the pressure difference between the inside and the outside of the
electric power steering apparatus so that water is prevented from
intruding into the inside of the electric power steering apparatus.
[0006]
Each of the conventional electric power steering apparatus
25 disclosed in Patent Document 1 and Patent Document 2 is configured
5
in such a way that as described above, a predetermined waterproof
property can be secured; however, when being installed in the vicinity
of a rack axel for turning tires of the vehicle, the electric power
steering apparatus is exposed to water and dust and may be submerged
in the water, in some cases; thus, it is required to 5 take waterproofing
measures having a considerable durability. Thus, it is required to
secure the waterproof property of the electric power steering
apparatus itself in which a motor and a control unit are integrated
with each other and to secure the waterproof property of the mounting
10 portion between the electric power steering apparatus and the vehicle.
[Prior Art Reference]
[Patent Literature]
[0007]
[Patent Document 1] Japanese Patent Application Laid-Open No.
15 2009-184492
[Patent Document 2] Japanese Patent Application Laid-Open No.
2005-132165
Disclosure of the Invention
20 Problems to be Solved by the Invention
[0008]
As described above, the conventional electric power steering
apparatus disclosed in Patent Document 1 is configured in such a way
that by use of a so-called O-ring, as a ring-shaped sealing member,
25 the waterproof property of the space between the motor and the
6
motor-mounting face of the gear housing is secured; however, the
output axel of the motor is pivotably supported by use of a bearing
whose waterproof property is not secured. Accordingly, by the
intermediary of the bearing, a respiratory action is performed between
the inside of the electric power steering apparatus 5 and a ventilation
path in the outer circumferential surface thereof.
[0009]
However, because the foregoing ventilation path communicates
with the outside by way of the inside of the gear housing provided
10 at the vehicle side and the circumferential surface of the rack axel,
a respiratory action, although slightly, is taken through the gear
housing; thus, sufficient waterproofing measures have not been taken.
Accordingly, because in some cases, water intrudes into the inside
of the gear housing, there has been a problem that when the foregoing
15 sealing member is deteriorated or broken, the waterproof property
of the electric power steering apparatus cannot be secured.
[0010]
The conventional electric power steering apparatus disclosed
in Patent Document 2 has a respiratory hole for performing a
20 respiratory action; a filter is inserted in the respiratory hole.
In general, because having water-repellency, a filter is impervious
to water but allows air to pass therethrough. Accordingly, the filter
inserted into the air inlet can exert a limited waterproof property
on sprinkled water like rain; however, there has been a problem that
25 for example, when the pressure difference between the inside and the
7
outside of the electric power steering apparatus, which is caused
by the temperature difference therebetween, becomes large, no
sufficient waterproof performance can be secured.
[0011]
The present disclosure has been implemented 5 in order to solve
the foregoing problems in conventional electric power steering
apparatuses; the objective thereof is to provide an electric power
steering apparatus that secures a sufficient waterproof property and
in which a motor and a control unit are integrated with each other.
10
Means for Solving the Problems
[0012]
An electric power steering apparatus disclosed in the present
application includes a motor for generating auxiliary torque
15 corresponding to steering torque exerted by a driver of a vehicle
and a control unit for controlling the motor; the motor and the control
unit are integrally coupled with each other, and the motor is mounted
in the vehicle through the intermediary of a gear unit. The electric
power steering apparatus is characterized
20 in that the motor has a motor housing in which motor constituent
members are contained, one axis-direction end portion of which is
sealed, and the other axis-direction end portion of which is opened,
in that the control unit has a control unit case in which control
apparatus constituent members are contained, one axis-direction end
8
portion of which is opened, and the other axis-direction end portion
of which is sealed,
in that the other axis-direction end portion of the motor
housing and the one axis-direction end portion of the control unit
case are coupled with each other while maintaining 5 a waterproofing
function,
In that the one axis-direction end portion of the motor housing
and the gear unit are coupled with each other while maintaining a
waterproofing function,
10 In that an output axle of the motor extends to the outside of
the motor housing while maintaining a waterproofing function, and
In that the motor housing has a respiratory apparatus that
performs a respiratory action, based on a pressure change in at least
one of the motor housing and the control unit.
15
Advantage of the Invention
[0013]
In the electric power steering apparatus disclosed in the
present application, the motor has a motor housing in which motor
20 constituent members are contained, one axis-direction end portion
of which is sealed, and the other axis-direction end portion of which
is opened; the control unit has a control unit case in which control
apparatus constituent members are contained, one axis-direction end
portion of which is opened, and the other axis-direction end portion
25 of which is sealed; the other axis-direction end portion of the motor
9
housing and the one axis-direction end portion of the control unit
case are coupled with each other while maintaining a waterproofing
function; the one axis-direction end portion of the motor housing
and the gear unit are coupled with each other while maintaining a
waterproofing function; an output axle of the motor 5 extends to the
outside of the motor housing while maintaining a waterproofing
function; the motor housing has a respiratory apparatus that performs
a respiratory action, based on a pressure change in at least one of
the motor housing and the control unit. As a result, it is made
10 possible to maintain a respiratory action and to suppress the
waterproof performance from being deteriorated.
Brief Description of the Drawings
[0014]
15 FIG. 1 is a configuration view illustrating a steering system
of a vehicle in which an electric power steering apparatus according
to Embodiment 1 is mounted;
FIG. 2 is a perspective view of the electric power steering
apparatus according to Embodiment 1;
20 FIG. 3 is a partial cross-sectional view of the electric power
steering apparatus according to Embodiment 1;
FIG. 4A is a plan view, at a control unit side, of the electric
power steering apparatus according to Embodiment 1;
FIG. 4B is a partial side view, at the control unit side, of
25 the electric power steering apparatus according to Embodiment 1; and
10
FIG. 5 is a partial cross-sectional view of the electric power
steering apparatus according to Embodiment 3.
Best Mode for Carrying Out the Invention
5 [0015]
Embodiment 1
Hereinafter, an electric power steering apparatus according
to Embodiment 1 will be explained in detail with reference to the
drawings. FIG. 1 is a configuration view illustrating a steering
10 system of a vehicle in which an electric power steering apparatus
according to Embodiment 1 is mounted. In FIG. 1, an electric power
steering apparatus 10 according to Embodiment 1 has a motor 7 and
a control unit 6 for controlling the motor 7. The motor 7 and the
control unit 6 are arranged in the axial direction on one and the
15 same axial line and are integrated with each other in such a way that
the respective axis-direction end portions facing each other are
coupled with each other. The electric power steering apparatus 10
is mounted to a gear unit 8 in such a way that the direction in which
the center axis thereof extends is in parallel with the direction
20 in which the center axis of a rack axel unit 2 extends.
[0016]
A torque sensor 3, provided in a steering column containing
a steering shaft 101, detects steering torque exerted by a driver
of a vehicle on the steering shaft 101 through the intermediary of
25 a steering wheel 1, and then inputs the steering torque to the control
11
unit 6 of the electric power steering apparatus 10. Based on the
steering torque inputted from the torque sensor 3, the control unit
6 controls the motor 7 so as to make the motor 7 generate auxiliary
torque corresponding to the steering torque exerted by the driver.
5 [0017]
The gear unit 8 mounted in the rack axel unit 2 has a gear
mechanism engaged with a rack axel contained in the rack axel unit
2 of the vehicle and with the output axel 11 of the motor 7, and drives
the rack axel unit 2 in the axial direction thereof, based on the
10 auxiliary torque outputted through the output axe of the motor 7,
so that steering of vehicle wheels 5 is turned. The steering shaft
101 is coupled with the rack axel unit 2 through the intermediary
of a pinion gear 4.
[0018]
15 As illustrated in FIG. 1, the torque sensor 3 is mounted at
a position farther from the ground G with respect to the rack axel
unit 2; the electric power steering apparatus 10 is mounted at a
position closer to the ground G with respect to the rack axel unit
2. Because as described above, the electric power steering apparatus
20 is mounted at a position closer to the ground G with respect to the
rack axel unit 2, it is indispensable that in comparison with a case
where the electric power steering apparatus is mounted above the rack
axel unit 2, a waterproof property conforming to a stricter
specification is secured.
25
12
[0019]
Next, the electric power steering apparatus according to
Embodiment 1 will be explained further in detail. FIG. 2 is a
perspective view of the electric power steering apparatus according
to Embodiment 1; FIG. 3 is a partial cross-sectional 5 view of the
electric power steering apparatus according to Embodiment 1; FIG.
4A is a plan view, at the control unit side, of the electric power
steering apparatus according to Embodiment 1; FIG. 4B is a partial
side view, at the control unit side, of the electric power steering
10 apparatus according to Embodiment 1. In each of FIGS. 2, 3, 4A, and
4B, the motor 7 has a cylindrical tubular motor housing 7a; motor
constituent members such as stator windings and a rotor are
incorporated in the motor housing 7a.
[0020]
15 The motor housing 7a is formed of metal, for example, aluminum,
and is provided with a housing wall portion 7b for sealing one
axial-direction end portion 7a1. The other axial-direction end
portion 7a2 of the motor housing 7a is opened and coupled with one
axial-direction end portion 6a1 of an after-mentioned control unit
20 case 6a in the control unit 6. An output axel 11 of the motor 7
penetrates the central portion of the housing wall portion 7b in the
motor housing 7a, through the intermediary of a bearing 12 and extends
in the axial direction. An output-axel gear 11a formed in the
axis-direction end portion of the output axel 11 is engaged with the
25 foregoing gear mechanism in the gear unit 8. With regard to the motor
13
housing 7a, because as described above, the one axial-direction end
portion 7a1 is formed to be bottomed due to the housing wall portion
7b, water intrusion into the motor 7 through the housing wall portion
7b, as a side surface of the motor 7, is completely blocked, except
for 5 the bearing 12.
[0021]
The bearing 12 may be either a bearing having a non-waterproof
structure or a bearing having a waterproof structure; in this
embodiment, the bearing 12 has a waterproof structure. In other words,
10 with regard to the bearing 12, there exist gaps in two or more positions
such as a position between the output axle 11 and a bearing inner
ring 121, a position between the bearing inner ring 121 and a bearing
outer ring 122, and a position between the bearing outer ring 122
and the housing wall portion 7b; thus, it is required to apply
15 waterproofing measures to all of these gaps.
[0022]
Accordingly, as illustrated in FIG. 3, an outer-circumference
O-ring 12a is inserted between the housing wall portion 7b and the
bearing outer ring 122, and a sealing member 12b, which is a metal
20 plate having a rubber material bonded to the outer circumference
thereof, is mounted between the bearing inner ring 121 and the bearing
outer ring 122. The output axle 11 and the bearing inner ring 121
are made to fit with each other through press-fitting or the like,
so that no gap exists between the bearing inner ring 121 and the outer
25 circumferential surface of the output axle 11. Accordingly, in the
14
electric power steering apparatus 10 according to Embodiment 1, no
respiratory path is formed in the periphery of the output axle 11,
especially through the bearing 12.
[0023]
The motor housing 7a has four motor fixing 5 portions 131, 132,
133, and 134 formed in such a way as to be spaced evenly apart from
one another in the peripheral portion of the one axial-direction end
portion 7a1 thereof. A ring-shaped U-shaped groove 14 in the surface
of the housing wall portion 7b is formed at the inner diameter side
10 with respect to the motor fixing portions 131, 132, 133, and 134 and
at the outer diameter side with respect to the bearing 12. A
ring-shaped O-ring (unillustrated) is inserted into the U-shaped
groove 14. In addition, the number of the motor fixing portions is
not limited to 4; it goes without saying that the number thereof may
15 be 3 or any of other numbers.
[0024]
The foregoing motor fixing portions 131, 132, 133, and 134 are
screwed to the motor mounting portion (unillustrated) of the gear
unit 8, so that the electric power steering device 10 is coupled with
20 the gear unit 8. In this situation, because the O-ring inserted into
the U-shaped groove 14 in the housing wall portion 7b of the electric
power steering device 10 is pressed against the surface of the motor
mounting portion of the gear unit 8, the waterproof property in the
coupling portion between the electric power steering device 10 and
25 the gear unit 8 is secured.
15
[0025]
A first respiratory apparatus 15, as a motor-side respiratory
apparatus, is provided in the housing wall portion 7b in such a way
as to be between the output axel 11 and the motor fixing portions
131, 132, 133, and 134. The first respiratory apparatus 5 15 includes
a penetration hole portion 15a provided in the bottom surface of a
U-shaped portion 15c formed in the outer surface portion of the housing
wall portion 7b and a filter 15b that has a water repellency and is
mounted inside the U-shaped portion 15c in such a way as to cover
10 the opening portion of the penetration hole portion 15a. The first
respiratory apparatus 15 is provided in the space between the bearing
12 and the U-shaped groove 14 in which the O-ring is mounted; however,
it is desirable that within the foregoing space, the first respiratory
apparatus 15 is disposed at an uppermost position in the radial
15 direction of the housing wall portion 7b. Unlike conventional
apparatuses, the electric power steering apparatus 10 according to
Embodiment 1 has the first respiratory apparatus 15, as the sole
respiratory path in the housing wall portion 7b.
[0026]
20 As described above, the first respiratory apparatus 15 is
disposed at a position surrounded by the bearing 12 to which
waterproofing measures are applied and the O-ring for preventing water
from intruding into the electric power steering device 10. The filter
15b makes the electric power steering device 10 secure a respiratory
25 function of allowing air but no water to pass therethrough. In
16
addition, the first respiratory apparatus 15 may be provided at an
arbitrary position in the outer circumferential surface of the motor
housing 7a, for example, in the vicinity of the vertex portion of
the outer circumferential surface of the motor housing 7a. In the
case where a pressure difference between the inside 5 and the outside
of the motor 7 occurs, the first respiratory apparatus 15 allows only
air to pass therethrough; thus, the pressure difference can be
eliminated.
[0027]
10 Meanwhile, the control unit 6 has a cylindrical tubular control
unit case 6a formed of, for example, an insulating resin; control
apparatus constituent members such as a circuit network for
controlling the motor 7 and the like are contained in the control
unit case 6a. The one axial-direction end face 6a1 of the control
15 unit case 6a is opened, and the other axial-direction end portion
6a2 thereof is sealed with a case wall portion 6b. The dimension of
the outer diameter of the control unit case 6a is formed to be a value
that is the same as the dimension of the outer diameter of the motor
housing 7a or a value that is extremely close thereto and is determined
20 as being substantially equal thereto; however, the dimension of the
outer diameter of the control unit case 6a may be formed to a value
other than the foregoing values.
[0028]
The control unit case 6a has three control unit fixing portions
25 161, 162, and 163 formed in such a way as to be spaced evenly apart
17
from one another in the peripheral portion of the one axial-direction
end face 6a1 thereof. The control unit fixing portions 161, 162, and
163 are screwed to three control-unit-fixing protrusion portions 171,
172, and another (in FIG. 2, only two thereof are illustrated) provided
in the other axial-direction end portion 7a2 of 5 the motor housing
7a, so that the control unit 6 is coupled with the motor 7. In this
situation, a waterproof packing is inserted into or a waterproof
sealing compound is applied to the space between the axis-direction
end face of the one axial-direction end portion 6a1 of the control
10 unit case 6a and the axis-direction end face of the other
axial-direction end portion 7a2 of the motor housing 7a, so that the
waterproof property of the coupling portion between the control unit
6 and the motor 7 is secured. In addition, each of the number of the
control unit fixing portions and the number of the fixing protrusion
15 portions is not limited to 3; it goes without saying that the number
thereof may be any of other numbers.
[0029]
In the case wall portion 6b, a power source connector 20, a
signal connector 21, an electric component containing portion 23,
20 and a second respiratory apparatus 22 are formed integrally with the
control unit case 6a. A vehicle-side power source connector 20a
connected with a power source harness 20b is connected with the power
source connector 20. A vehicle-side signal connecter 21a connected
with a signal harness 21b for transmitting signals or the like from
25 the torque sensor 3 is connected with the signal connector 21. Large
18
electric components such as a noise filter and a capacitor are
contained in the electric component containing portion 23. The power
source connector 20, the vehicle-side power source connector 20a,
the signal connector 21, and the vehicle-side signal connecter 21a
are formed conforming to respective waterproof 5 specifications.
[0030]
FIG. 4B illustrates the state where the vehicle-side power
source connector 20a connected with the power source harness 20b is
connected with the power source connector 20 and where the
10 vehicle-side signal connecter 21a connected with the signal harness
21b is connected with the signal connector 21; FIG. 4A illustrates
the state where the vehicle-side power source connector 20a is not
connected with the power source connector 20 and where the
vehicle-side signal connecter 21a is not connected with the signal
15 connector 21.
[0031]
The power source connector 20 has two terminals, i.e., a
positive-side power source connection terminal 20d1 and a
negative-side power source connection terminal 20d2; the respective
20 cross-sectional areas of these terminals are made large so that a
large current for driving the motor 7 can be supplied. A large number
of relatively small signal connection terminals 21d are arranged in
the signal connector 21 so that in addition to information from the
torque sensor 3, vehicle-side information such as a vehicle speed
25 is inputted therethrough and a transmission signal from the control
19
unit 6 is outputted therethrough. As illustrated in FIG. 1, the
electric power steering apparatus 10 is mounted at a lowest position
of the vehicle, and a vehicle battery (unillustrated), a vehicle speed
sensor (unillustrated), and the like are provided at positions upper
than the position where the electric power steering 5 apparatus 10 is
provided; therefore, all of the power source harness 20b and the signal
harness 21b extend toward the upper side of the vehicle.
[0032]
The second respiratory apparatus 22, as a control-unit-side
10 respiratory apparatus, is provided in the vicinity of the power source
connector 20 and the signal connector 21 in the case wall portion
6b of the control unit case 6a. The second respiratory apparatus 22
has a hollow protrusion portion 22a and a filter 22b having a
water-repellency. The hollow protrusion portion 22a protrudes in the
15 axial direction of the control unit 6 from the axis-direction endface
portion of the case wall portion 6b and makes the respective insides
of the control unit case 6a and the motor housing 7a communicate with
the outside of the electric power steering apparatus 10. The filter
22b is mounted in such a way as to cover the root portion of the hollow
20 protrusion portion 22a, i.e., the opening portion that opens toward
the inside of the control unit case 6a.
[0033]
When the motor 7 is driven, the electronic components and large
electric components such as the noise filter and the capacitor
25 included in the circuit network and the like contained in the control
20
unit 6 generate heat. When being driven, the motor 7 itself also
generates heat. Accordingly, a heat radiation member such as a heat
sink is contained in the control unit case 6a; the heat generated
by the foregoing components is transferred also to the motor
constituent members included in the motor 7 through 5 the heat sink
or in a direct manner.
[0034]
At a vehicle-driving time when the electric power steering
apparatus 10 is driven, air in the electric power steering apparatus
10 10 expands due to the foregoing heat generation; in contrast, at a
vehicle-drive-stoppage time when the electric power steering
apparatus 10 is stopped, the temperature of the electric power
steering apparatus 10 decreases and hence the air therein contracts;
thus, the pressure inside the electric power steering apparatus 10
15 becomes a negative pressure. As a result, a respiratory action occurs
in the electric power steering apparatus 10. Moreover, in the case
where the electric power steering apparatus 10 is mounted at the lowest
position of the vehicle, there exists a probability that for example,
when the vehicle travels in a road puddle, the whole electric power
20 steering apparatus 10 is submerged in the water.
[0035]
Because communicating with the respective insides of the
control unit case 6a and the motor housing 7a, the second respiratory
apparatus 22 makes it possible that the foregoing respiratory action
25 in the electric power steering apparatus 10 is performed. Moreover,
21
the second respiratory apparatus 22 is provided with the filter 22b
having a water repellency; thus, even when water intrudes into the
hollow protrusion portion 22a of the second respiratory apparatus
22, the water can be prevented from intruding into the control unit
5 case 6a.
[0036]
In order to reduce water, dust, and like as much as possible,
it is desirable that the respiration opening of the second respiratory
apparatus 22 is disposed at an uppermost position in the case wall
10 portion 6b of the control unit case 6a. When the hollow protrusion
portion 22a of the second respiratory apparatus 22 is formed to be
long in the axis direction, intrusion of water, dust, or the like
can further be reduced. In addition, when the second respiratory
apparatus 22 is not provided in the case wall portion 6b but is disposed
15 in the vicinity of the vertex portion of the cylindrical tubular outer
circumferential surface of the control unit case 6a, it is made
possible to make the second respiratory apparatus 22 situated at a
further upper position. In addition, the respiration opening of the
second respiratory apparatus may be disposed at a position that is
20 upper in the vertical direction than the respiration opening of the
first respiratory apparatus.
[0037]
In the motor 7, for example, there exist a gap between the stator
and the rotor and a gap between the outer circumferential surface
25 of the stator and the inner circumferential surface of the motor
22
housing 7a; in the inside of the control unit 6, a CPU (Central
Processing Unit), various kinds of electric lines, an IC (Integrated
Circuit), a driving circuit for driving the motor 7, and the like
are mounted on a substrate, a relay member, a heat sink, and the like;
among the substrate, the relay member, the heat sink, 5 and the control
unit case 6a, a great number of spaces exist. Accordingly, the
foregoing gaps and spaces inside the electric power steering apparatus
10 function as ventilation paths, in the electric power steering
apparatus 10, that communicate with the first respiratory apparatus
10 15 and the second respiratory apparatus 22.
[0038]
As described above, because the electric power steering
apparatus according to Embodiment 1 is provided with the first
respiratory apparatus, as the motor-side respiratory apparatus, and
15 the second respiratory apparatus, as the control-unit-side
respiratory apparatus, waterproofing measures are applied to the
motor itself and the control unit itself; in addition, although
waterproofing measures are applied to the coupling portion between
the motor and the control unit, it is made possible to make the electric
20 power steering apparatus maintain the respiratory function thereof.
Moreover, in Embodiment 1, each of the first respiratory apparatus
and the second respiratory apparatus has a filter having a water
repellency; thus, the waterproofing function of the whole electric
power steering apparatus can be secured. Moreover, the respective
25 respiratory functions of the first respiratory apparatus and the
23
second respiratory apparatus make it possible that the respective
waterproofing functions based on the waterproofing measures applied
to the motor itself and the control unit itself and based on the
waterproofing measures applied to the coupling portion between the
motor and the control unit are prevented from being 5 deteriorated.
[0039]
In the foregoing explanation, both of the first respiratory
apparatus, as the motor-side respiratory apparatus, and the second
respirator apparatus, as the control-unit-side respiratory apparatus,
10 are provided; however, because even only any one of the respiratory
apparatuses makes it possible to secure the respiratory function,
it is allowed that only any one of the respiratory apparatuses is
provided.
[0040]
15 Because the second respiratory apparatus 22 has a higher
probability of being inundated with water than the first respiratory
apparatus 15, it is desirable that the second respiratory apparatus
22 is disposed at a position upper than the position of the first
respiratory apparatus 15.
20 [0041]
Embodiment 2
Next, an electric power steering apparatus according to
Embodiment 2 will be explained. The electric power steering
apparatus according to Embodiment 2 is characterized by including
25 the first respiratory apparatus, as a motor-side respiratory
24
apparatus, and the second respiratory apparatus, as a
control-unit-side respiratory apparatus, and characterized in that
the level of the respiratory function of the second respiratory
apparatus is made higher than that of the respiratory function of
the first respiratory apparatus. The other 5 configurations and
operational actions thereof are the same as those of the electric
power steering apparatus according to Embodiment 1.
[0042]
Comparison between the foregoing first respiratory apparatus
10 15 and the second respiratory apparatus 22 indicates that there exists
a large difference between the respective external environments where
the foregoing respiratory apparatuses are arranged. That is to say,
the ventilation path communicating with the first respiratory
apparatus 15 is connected with the outside from the inside of the
15 electric power steering apparatus 10, by way of the gear unit 8 and
the rack axel unit 2. In contrast, the ventilation path communicating
with the second respiratory apparatus 22 expands from the inside of
the electric power steering apparatus 10 toward the outer air; thus,
the respiratory resistance and the pressure loss of the second
20 respiratory apparatus 22 is smaller than those of the first
respiratory apparatus 15. Accordingly, in comparison with raising
the respiratory function of the first respiratory apparatus 15, it
is easy to raise the respiratory function of the second respiratory
apparatus 22.
25 [0043]
25
Accordingly, in the electric power steering apparatus
according to Embodiment 2, there have been taken measures for securely
making the respiratory function of the second respiratory apparatus
higher than the respiratory function of the first respiratory
apparatus. The specific measure for raising the respiratory 5 function
of the second respiratory apparatus 22 can be obtained by making the
air permeability of the water-repellent filter 22b of the second
respiratory apparatus 22 higher than that of the water-repellent
filter 15b of the first respiratory apparatus 15, by making the
10 diameter of the water-repellent filter 22b of the second respiratory
apparatus 22 larger than that of the water-repellent filter 15b of
the first respiratory apparatus 15, by making the diameter of the
penetration hole portion of the second respiratory apparatus 22 larger
than that of the penetration hole portion of the first respiratory
15 apparatus 15, or by combining some of the above measures.
[0044]
Because regardless of the level of the respiratory function,
the second respiratory apparatus 22 has a higher probability of being
inundated with water than the first respiratory apparatus 15, it is
20 desirable that the second respiratory apparatus 22 is disposed at
a position upper than the position of the first respiratory apparatus
15.
[0045]
As described above, the electric power steering apparatus
25 according to Embodiment 2 includes the first respiratory apparatus,
26
as a motor-side respiratory apparatus, and the second respiratory
apparatus, as a control-unit-side respiratory apparatus, and the
respiratory function of the second respiratory apparatus is made
higher than the respiratory function of the first respiratory
apparatus; therefore, it is made possible that 5 the respiratory
function of the electric power steering apparatus is secured and
raised.
[0046]
Embodiment 3
10 Next, an electric power steering apparatus according to
Embodiment 3 will be explained. FIG. 5 is a partial cross-sectional
view of the electric power steering apparatus according to Embodiment
3. In FIG. 5, on the side-surface portion, at the anti-motor side,
of the bearing 12 having no waterproof property, an oil seal portion
15 18 is mounted between the output axle 11 and a bearing mounting portion
7b1 of the housing wall portion 7b. The oil seal 18 includes a seal
lip 18a made of, for example, a fluoride resin, an outer circumference
metal ring 18b, and an inner circumference metal ring 18c; the outer
circumferential portion of the seal lip 18a is pinched by the outer
20 circumference metal ring 18b and the inner circumference metal ring
18c. The inner circumferential surface of the seal lip 18a makes tight
contact with and slides on the outer circumferential surface of the
output axle 11. The foregoing configuration secures the
waterproofing function in the peripheral portion of the bearing 12.
25 [0047]
27
At the radially outside of the bearing 12 and the oil seal 18,
the U-shaped portion 15c is provided in the housing wall portion 7b
of the motor housing 7a; the penetration hole portion 15a is provided
in the central portion of the U-shaped portion 15c. The filter 15b
having a water repellency is mounted inside the U-5 shaped portion 15c
in such a way as to cover the opening portion, at the anti-motor side,
of the penetration hole portion 15a. Although in comparison with the
bearing 12, the axial-direction length of the bearing mounting portion
7b1 in the housing wall portion 7b of the motor housing 7a becomes
10 large, a spatial margin exists in the axial direction (in the
left-and-right direction in the drawing) of the first respiratory
apparatus 15; therefore, the inner diameter of the opening portion,
at the motor side, of the penetration hole portion 15a can be made
smaller than the inner diameter of the opening portion with the filter
15 15b mounted thereto, at the anti-motor side, of the penetration hole
portion 15a.
[0048]
Because being determined by the respective inner diameters of
the water-repellent filter 15b and the opening portion, at the
20 anti-motor side, of the penetration hole portion 15a, the respiratory
resistance of the first respiratory apparatus 15 does not change even
when the inner diameter, at the motor side, of the opening portion
is made smaller. Decreasing the inner diameter of the opening portion,
at the motor side, of the penetration hole portion 15a makes it
25 possible to prevent foreign materials from intruding into the
28
penetration hole portion 15a, without reducing the respiratory
resistance.
[0049]
As described above, in the electric power steering apparatus
according to Embodiment 3, the waterproof property 5 of the peripheral
portion of the output axle 11 is secured by the oil seal 18, so that
while demonstrating a chimney effect and an effect of preventing
intrusion by foreign materials, obtained through the length of the
penetration hole portion 15a in the first respiratory apparatus 15,
10 the number of water intrusion paths into the electric power steering
apparatus 10 can be decreased without reducing the respiratory
resistance and hence the waterproof property can be raised.
[0050]
Although the present application is described above in terms
15 of various exemplary embodiments and implementations, it should be
understood that the various features, aspects and functions described
in one or more of the individual embodiments are not limited in their
applicability to the particular embodiment with which they are
described, but instead can be applied, alone or in various
20 combinations to one or more of the embodiments. Therefore, an
infinite number of unexemplified variant examples are conceivable
within the range of the technology disclosed in the present
application. For example, there are included the case where at least
one constituent element is modified, added, or omitted and the case
29
where at least one constituent element is extracted and then combined
with constituent elements of other embodiments.
Industrial Applicability
5 [0051]
An electric power steering apparatus according to the present
application can be applied to the field of a vehicle such as an
automobile.
10 Description of Reference Numerals
[0052]
1: steering wheel 2: rack axel unit 3: torque sensor 4: pinion gear
5: vehicle wheel 6: control unit 6a: control unit case 6b: case
wall portion 7: motor 7a: motor housing 7b: housing wall portion
15 7b1: bearing mounting portion 8: gear unit 10: electric power
steering apparatus 11: output axle 11a: output-axel gear 12:
bearing 14: U-shaped groove 15: first respiratory apparatus 15a:
penetration hole portion 15c: U-shaped portion 18: oil seal
18a: seal lip 18b: outer circumference metal ring 18c: inner
20 circumference metal ring 15b, 22b: filter 20: power source
connecter 20a: vehicle-side power source connector 20b: power
source harness 20d1, 20d2: power source connection terminal 21:
signal connector 21a: vehicle-side signal connector 21b: signal
harness 21d: signal connection terminal 22: second respiratory
25 apparatus 22a: hollow protrusion portion 23: electric component
30
containing portion 101: steering shaft 131, 132, 133, 134: motor
fixing portion 161, 162, 163: control unit fixing portion 171, 172:
control-unit-fixing protrusion portion
31
We Claim:
1. An electric power steering apparatus comprising:
a motor for generating auxiliary torque corresponding to
steering torque exerted by a driver of a vehicle; and
a control unit for controlling 5 the motor,
wherein the motor and the control unit are integrally coupled
with each other and the motor is mounted in the vehicle through the
intermediary of a gear unit,
wherein the motor has a motor housing in which motor constituent
10 members are contained, one axis-direction end portion of which is
sealed, and the other axis-direction end portion of which is opened,
wherein the control unit has a control unit case in which control
apparatus constituent members are contained, one axis-direction end
portion of which is opened, and the other axis-direction end portion
15 of which is sealed,
wherein the other axis-direction end portion of the motor
housing and the one axis-direction end portion of the control unit
case are coupled with each other while maintaining a waterproofing
function,
20 wherein the one axis-direction end portion of the motor housing
and the gear unit are coupled with each other while maintaining a
waterproofing function,
wherein an output axle of the motor extends to the outside of
the motor housing while maintaining a waterproofing function, and
32
wherein the motor housing has a respiratory apparatus that
performs a respiratory action, based on a pressure change in at least
one of the motor housing and the control unit.
2. The electric power steering apparatus according 5 to claim 1,
wherein the motor housing is provided with a bearing that has
a waterproofing function and pivotably supports the output axle,
wherein the motor housing is coupled with the gear unit through
the intermediary of an O-ring, and
10 wherein the respiratory apparatus is disposed at a position
that is between the O-ring and the bearing and is upper in the vertical
direction than the output axle.
3. The electric power steering apparatus according to any one of claims
15 1 and 2, wherein the control unit case has a respiratory apparatus
that performs a respiratory action, based on a pressure change in
at least one of the motor housing and the control unit.
4. The electric power steering apparatus according to any one of claims
20 1 through 3, wherein the respiratory apparatus provided in the control
unit case is configured in such a way as to have a higher respiratory
function than the respiratory apparatus provided in the motor housing
has.
25 5. The electric power steering apparatus according to claim 2,
33
wherein the bearing has a bearing outer ring and a bearing inner
ring,
wherein an O-ring is inserted between the motor housing and
the bearing outer ring, and
wherein a sealing member is mounted between 5 the bearing inner
ring and the bearing outer ring.
6. The electric power steering apparatus according to claim 2, further
comprising an oil seal that makes contact with the side surface, at
10 the anti-motor side, of the bearing.
7. The electric power steering apparatus according to claim 3,
wherein the respiratory apparatus provided in the control unit
case includes a penetration hole provided in the control unit case
15 and a water-repellent filter that covers an opening portion of the
penetration hole, and
wherein the respiratory apparatus provided in the motor housing
includes a penetration hole provided in the motor housing and a
water-repellent filter that covers an opening portion of the
20 penetration hole.
8. The electric power steering apparatus according to any one of claims
1 through 7, wherein the electric power steering apparatus is disposed
34
at a lower position than a rack axel of the vehicle is.