JP3762547B2 - Power steering device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power steering apparatus having a hydraulic actuator that generates a steering assist force based on the pressure of oil discharged from a pump driven by an electric motor.
[0002]
[Prior art]
In a power steering device that generates a steering assist force by a hydraulic actuator based on the pressure of oil discharged from a tank by a pump driven by an electric motor, if the motor is always held at a speed required for steering assist, the motor This wastes the energy of the battery that serves as the power source.
[0003]
In view of this, it has been attempted to reduce the fuel consumption of the vehicle by providing a control device that sets the rotation speed of the motor to the steering assist speed only at the time of steering assist and to the standby speed when the steering assist is released.
[0004]
The control device includes a switching element such as an FET (field effect transistor) and a circuit element such as a shunt resistor in order to control electric power supplied to the motor. Such a circuit element generates a large amount of heat because a large current flows. Therefore, it has been proposed to cool the control device by disposing it near the hydraulic oil piping of the hydraulic actuator (see Japanese Patent Application Laid-Open No. 58-145572).
[0005]
[Problems to be solved by the invention]
However, the conventional configuration has a problem that the control device cannot be sufficiently cooled, and the stability of the control device is hindered by heat generation.
[0006]
It is an object of the present invention to provide a power steering device that can solve the above-described problems.
[0007]
[Means for Solving the Problems]
The present invention relates to a tank, a pump for circulating oil in the tank, an electric motor that drives the pump, and a hydraulic actuator that generates a steering assist force based on the pressure of the oil discharged from the pump. The present invention is applied to a power steering device for a vehicle including a control device that sets the rotational speed of the motor to a steering assist speed at the time of steering assist and to a standby speed lower than the steering assist speed at the time of steering assist release.
[0008]
According to a first aspect of the present invention, the tank in the power steering device includes a metal heat absorption part having thermal conductivity, and a metal heat radiation fin integrated with the heat absorption part. The control device is joined to the heat absorption portion from the control device so as to be able to conduct heat, and the fins are arranged to be immersed in oil in the tank.
According to this configuration, the heat generated by the control device is conducted to the fin through the heat absorbing portion, and is radiated from the fin into the oil.
[0009]
It is preferable that the fin is disposed at a position in contact with the oil flow from the inlet to the outlet in the tank, and has a streamline shape so that the oil flows smoothly.
According to this configuration, the fin is in contact with the oil flow and does not hinder the oil flow, so that heat can be efficiently radiated from the fin.
[0010]
The second feature of the present invention is that in the power steering device, the control device has a heat radiation fin, and a mechanism for blowing cooling air to the fin is provided.
According to this configuration, the heat generated by the control device is conducted to the fin and radiated from the fin into the air. At this time, since cooling air is blown onto the fins, heat can be radiated efficiently.
[0012]
The power steering device having the second feature includes a pinion that rotates by steering, a rack that meshes with the pinion, a housing that covers the rack, and a cover that covers the rack that protrudes from the housing, and the rotation of the pinion The rudder angle is changed by the movement of the rack, and the cover can be expanded and contracted so that the volume is increased or decreased by the movement of the rack, and the cooling air blowing mechanism is discharged from the cover when the volume is reduced. the that air, have a pipe leading to the fin, the pipe is provided outside of the housing and the cover, one end of the pipe is connected to a vent hole leading to the interior of the housing and the cover, the The other end of the pipe is disposed at a position facing the fin .
According to this configuration, the cooling air can be blown to the fins using the movement of the rack during steering. Moreover, since the cooling air is blown at the time of steering when the heat generated by the control device increases, cooling can be performed efficiently.
[0013]
It is preferable that the cooling air blowing mechanism has a pipe that guides air introduced from the outside of the vehicle into the vehicle during traveling to the fins.
According to this configuration, air introduced from the outside of the vehicle during traveling can be blown onto the fins as cooling air, and cooling can be performed efficiently.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment of the present invention will be described with reference to FIGS.
A rack and pinion type power steering apparatus 1 shown in FIG. 1 includes an input shaft 2 connected to a steering wheel H, and an output shaft 4 connected to the input shaft 2 via a torsion bar 3. The torsion bar 3 is connected to the input shaft 2 via a pin 5 and connected to the output shaft 4 via a serration 6. A pinion 7 is formed on the output shaft 4, and a rack 8 that meshes with the pinion 7 is connected to a wheel (not shown). The input shaft 2 is supported by a valve housing 10 a via a bearing 9, and is supported by an output shaft 4 via a bush 11. The output shaft 4 is supported by a pinion housing 10b via bearings 12 and 13. Oil seals 14 and 15 are provided between the input / output shafts 2 and 4 and the valve housing 10a. A support yoke 16 that supports the rack 8 is provided, and the support yoke 16 is pressed against the rack 8 by the elasticity of the spring 17.
[0015]
As shown in FIGS. 2 and 3, one end side of the rack 8 protruding from one end of the pinion housing 10 b is covered with a cylindrical rack housing 43. One end of the rack 8 protruding from the one end opening 43a of the rack housing 43 and the other end of the rack 8 protruding from the other end opening 10b 'of the pinion housing 10b are respectively connected to tie rods 45a and 45b via ball joints 44a and 44b. And are connected to wheels (not shown) via the tie rods 45a and 45b. As a result, the rotation of the input shaft 2 due to steering is transmitted to the pinion 7 via the torsion bar 3, so that the rack 8 moves in the vehicle width direction. The rudder angle changes as the rack 8 moves.
[0016]
The rack 8 protruding from one end opening 43a of the rack housing 43 and the other end opening 10b 'of the pinion housing 10b is covered with elastically deformable cylindrical expansion / contraction covers 46a and 46b made of synthetic resin, respectively. Each expansion / contraction cover 46a, 46b can be expanded and contracted in the axial direction of the rack 8 by having a bellows-like peripheral wall. One extensible cover 46a has one end fitted on the outer circumference of the rack housing 43 and the other end fitted on the outer circumference of the tie rod 45a. One end of the other telescopic cover 46b is fitted to the outer periphery of the pinion housing 10b, and the other end is fitted to the outer periphery of the tie rod 45b. Thereby, the expansion and contraction covers 46a and 46b expand and contract by the movement of the rack 8, and the volume of the expansion and contraction covers 46a and 46b increases and decreases by this expansion and contraction. The rack housing 43 is formed with a vent hole 43 ″ that leads to the inside of one of the expansion covers 46a so that the internal pressure of each of the expansion covers 46a, 46b does not fluctuate due to the expansion and contraction, and the pinion housing 10b has an inside of the other expansion cover 46b. A vent hole 10b ″ is formed.
[0017]
A pair of seal members 18a and 18b for sealing between the inner periphery of the rack housing 43 and the outer periphery of the rack 8 are provided, and the piston 20 is attached to the rack 8 between the seal members 18a and 18b. A pair of oil chambers 21 and 22 are partitioned by the piston 20 between the two seal members 18a and 18b. Thus, the hydraulic cylinder 18 is configured as a hydraulic actuator that applies a steering assist force.
[0018]
A rotary hydraulic control valve 23 built in the valve housing 10a is connected to the oil chambers 21 and 22 via pipes 19a and 19b. As shown in FIGS. 1 and 4, the control valve 23 includes a cylindrical first valve member 24 and a second valve member 25 that is inserted into the first valve member 24 so as to be relatively rotatable. . The first valve member 24 is attached to the output shaft 4 via a pin 26 so as to be able to rotate together. The second valve member 25 is integrally formed on the outer periphery of the input shaft 2.
[0019]
A plurality of recesses along the axial direction are formed at equal intervals in the circumferential direction on the inner periphery of the first valve member 24 and the outer periphery of the second valve member 25.
The first valve member-side recesses are composed of four right steering recesses 27 positioned at equal intervals in the circumferential direction and four left steering recesses 28 positioned at equal intervals in the circumferential direction.
The second valve member side recesses are constituted by four pressure oil supply recesses 29 located at equal intervals in the circumferential direction and four pressure oil discharge recesses 30 positioned at equal intervals in the circumferential direction.
The right steering recesses 27 and the left steering recesses 28 are alternately arranged in the circumferential direction, and the pressure oil supply recesses 29 and the pressure oil discharge recesses 30 are alternately arranged in the circumferential direction.
As shown in FIG. 1, each of the right steering recesses 27 has one oil chamber of the hydraulic cylinder 18 from a first flow path 31 formed in the first valve member 24 and a first port 32 formed in the valve housing 10a. 21 is communicated with the pipe 19a. Each left steering recess 28 connects a pipe 19b to the other oil chamber 22 of the hydraulic cylinder 18 through a second flow path 33 formed in the first valve member 24 and a second port 34 formed in the valve housing 10a. Through.
Each pressure oil supply recess 29 is connected to a pipe 19c from the third flow path 35 formed in the first valve member 24 and the inlet port 36 formed in the valve housing 10a to the discharge side of the pump 37 as shown in FIG. Through. The pump 37 is driven by an electric motor 50 such as a brushless motor, and can be constituted by, for example, a vane pump or a gear pump that discharges pressure oil at a flow rate corresponding to the rotation speed of the motor 50.
Each pressure oil discharge recess 30 is formed in the first discharge path 38 formed in the second valve member 25, the passage 47 between the inner and outer periphery of the input shaft 2 and the torsion bar 3, and the input shaft 2 shown in FIG. The second exhaust path 39 and the exhaust port 40 formed in the valve housing 10a lead to the tank 71 through the pipe 19d.
Thus, the oil passages that connect the oil chambers 21 and 22 of the pump 37, the tank 71, and the hydraulic cylinder 18 through the inter-valve flow path 42 between the inner and outer peripheries of the first valve member 24 and the second valve member 25. The oil in the tank 71 is circulated by the pump 37 through the oil passage.
Between the first valve member side concave portion and the second valve member side concave portion in the inter-valve flow path 42 are throttle portions A, B, C, and D whose opening degree changes due to relative rotation of both valve members 24 and 25. The The hydraulic pressure acting on the hydraulic cylinder 18 is controlled by changing the opening of the throttle portions A, B, C, and D.
[0020]
FIG. 4 shows the relative positions of the valve members 24 and 25 at the steering angle midpoint where steering is not performed. In this state, each of the pressure oil supply recesses 29 and each of the pressure oil discharge recesses 30 communicate with each other via all throttle portions A, B, C, and D. Therefore, the pressure oil supplied from the pump 37 directly returns to the tank 71 and no steering assist force is generated. Therefore, it is not necessary to drive the motor 50 at the steering assist speed necessary for steering assist.
[0021]
When steering to the right from the steering angle midpoint, the torsion bar 3 is twisted according to the steering torque, and both valve members 24 and 25 rotate relative to each other. As a result, the opening degree of the throttle portion A between each right steering concave portion 27 and each pressure oil supply concave portion 29 and the throttle portion B between each left steering concave portion 28 and each pressure oil discharge concave portion 30. The opening increases, and the opening of the throttle C between each left steering recess 28 and each pressure oil supply recess 29 and the throttle between each right steering recess 27 and each pressure oil discharge recess 30. The opening degree of the part D becomes small. Thereby, the oil in the tank 71 is circulated by the pump 37, pressure oil is supplied to one oil chamber 21 of the hydraulic cylinder 18, and the oil recirculates from the other oil chamber 22 of the hydraulic cylinder 18 to the tank 71. Based on the pressure of the oil discharged from the pump 37, a steering assist force to the right generated by the hydraulic cylinder 18 acts on the rack 8.
[0022]
When steering leftward from the rudder angle midpoint, the apertures of the throttles A, B, C, and D change in the opposite direction to when steering rightward. Thereby, the oil in the tank 71 is circulated by the pump 37, pressure oil is supplied to the other oil chamber 22 of the hydraulic cylinder 18, and the oil recirculates from the one oil chamber 21 of the hydraulic cylinder 18 to the tank 71. Based on the pressure of the oil discharged from the pump 37, a leftward steering assist force generated by the hydraulic cylinder 18 acts on the rack 8.
[0023]
As shown in FIG. 1, the motor 50 is connected to a control device 60. The control device 60 includes a control circuit 61 and a drive circuit 62. The rotational speed of the motor 50 is set to a steering assist speed at the time of steering assist, and is set to a standby speed lower than the steering assist speed at the time of steering assist release. .
[0024]
The control circuit 61 is configured by a computer and outputs an instruction signal to the drive circuit 62 based on a signal from the steering angle sensor 51 that detects the steering angle of the steering wheel H. That is, the control circuit 61 determines the presence or absence of steering based on the signal from the steering angle sensor 51. For example, when the steering angle detected by the rudder angle sensor 51 is equal to or greater than a preset reference value corresponding to the play of the steering wheel H, it is determined that steering is present. Further, when there is no change in the rudder angle, or when the rudder angle is less than the reference value for a certain time, it is determined that there is no steering. When it is determined that steering is present, an instruction signal for setting the rotation speed of the motor 50 to the steering assist speed is output to the drive circuit 62. The steering assist speed is set in advance so that the flow rate of pressure oil discharged from the pump 37 becomes a flow rate necessary for assisting steering. If it is determined that there is no steering, an instruction signal for setting the rotation speed of the motor 50 to the standby speed is output to the drive circuit 62 to release the steering assist. The standby speed when the steering assist is released is lower than the steering assist speed and may be zero.
[0025]
The drive circuit 62 includes a power control circuit element such as an FET or a shunt resistor, and supplies power corresponding to an instruction signal from the control circuit 61 from the battery power supply 63 to the motor 50.
[0026]
As shown in (1), (2), and (3) of FIG. 5, the tank 71 includes a tank body 72 and a cap 73 that opens and closes an oil filler opening formed in the tank body 72. An inlet 72 a and an outlet 72 b are formed in the tank main body 72. A pipe 19d connected to the discharge port 40 of the hydraulic control valve 23 is connected to the inlet 72a, and a pipe 19e connected to the suction side of the pump 37 is connected to the outlet 72b.
[0027]
The bottom wall of the tank body 72 is a metal heat absorption part 74 having thermal conductivity. In the present embodiment, the entire tank main body 72 is made of metal such as aluminum having high thermal conductivity, but at least the heat absorbing portion 74 only needs to be made of metal. A plurality of metal heat dissipating fins 75 are formed integrally with the heat absorbing portion 74. Each fin 75 is disposed so as to be immersed in the oil 76 in the tank 71. Further, the fins 75 are plate-like and parallel to each other, and the thickness direction thereof is orthogonal to the oil flow direction (indicated by arrow a in FIG. 5 (2)) from the inlet 72a to the outlet 72b. Is arranged.
[0028]
The heat absorption part 74 is joined to the control device 60 so as to conduct heat from the control device 60 to the heat absorption part 74. In the present embodiment, the control device 60 has a substrate 60 ′ on which the control circuit 61 and the drive circuit 62 are provided on the surface side, and a cover 60 ″ that covers circuit elements on the surface side of the substrate 60 ′. Then, the substrate 60 ′ and the tank body 72 are connected by screws or the like so that the back surface of the substrate 60 ′ is in close contact with the heat absorbing portion 74.
[0029]
Instead of the substrate 60 ′, a cover 60 ″ may be brought into close contact with the heat absorbing portion 74. Further, a circuit element such as an FET or a shunt resistor in the control device 60 is interposed via an insulating material having thermal conductivity. The heat absorbing portion 74 may be joined to the heat absorbing portion 74. As the insulating material having such heat conductivity, for example, a heat conductive rubber sheet containing glass fibers can be used.
[0030]
According to the above configuration, the heat generated by the control device 60 is conducted to the fins 75 via the heat absorbing portion 74 of the tank 71 and is radiated from the fins 75 into the oil 76.
[0031]
As shown in FIG. 6, pipes 19a and 19b connecting the control valve 23 and the hydraulic cylinder 18, a pipe 19c connecting the pump 37 and the control valve 23, a pipe 19d connecting the tank 71 and the control valve 23, a tank 71 and the pump It is preferable to provide a flange-like heat dissipating fin 19 ′ on the outer periphery of the pipe 19 e connecting the pipe 37 to reduce the temperature of the oil circulated by the pump 37. Thereby, the heat generated with the pressure loss due to the friction between the oil and the piping can be dissipated into the atmosphere. Therefore, the cooling effect of the control device 60 can be improved. Moreover, damage to the pipes 19a, 19b, 19c, 19d, and 19e due to heat can be prevented and the life can be extended. The pipes 19a, 19b, 19c, 19d, and 19e may be steel pipes or rubber pipes.
[0032]
FIG. 7 shows a modification of the first embodiment. In this modification, the metal heat dissipating fin 75 ′ integrated with the metal heat absorbing portion 74 is disposed at a position in contact with the oil flow from the inlet 72 a to the outlet 72 b of the tank 71. Therefore, the inflow port 72a and the outflow port 72b are formed in the tank main body 72 below the example shown in FIG. Further, each fin 75 ′ has a streamline shape shown in (3) of FIG. 7 so that the oil flow becomes smooth. As a result, each fin 75 'is in contact with the oil flow and does not hinder the oil flow, so that heat can be efficiently radiated from the fin 75'. Others are the same as in the first embodiment, and the same parts are denoted by the same reference numerals.
[0033]
(1) and (2) in FIG. 8 show comparative examples of the present invention. Hereinafter, differences from the first embodiment will be described, and the same parts are denoted by the same reference numerals. In the first embodiment, the heat generated by the control device is radiated into the oil. Instead, in the comparative example , the heat is radiated into the air. That is, the control device 160 includes a substrate 160 ′ provided with a control circuit and a drive circuit similar to those in the first embodiment, and a box-shaped casing 160 ″ covering the substrate 160 ′. A plurality of plate-like heat radiation fins 175 are attached to the entire outer periphery of the casing 160 ″. A mechanism 180 for blowing cooling air to the fins 175 formed on one side wall closest to the substrate 160 ′ in the casing 160 ″ as shown by an arrow in FIG.
[0034]
The cooling air blowing mechanism 180 includes a cooling air blowing fan 180a and a drive motor 180b for the fan 180a. The fan drive motor 180 b is supported on the vehicle body side via a bracket 181 attached to the control device 160. The fan drive motor 180b is controlled by the control device 160. That is, the rotational speed of the pump drive motor 50 is set to the steering assist speed at the time of steering assistance, and at the same time, the rotation speed of the fan drive motor 180b is set to a preset cooling acceleration speed. At the same time as the rotation speed is set to the standby speed, the rotation speed of the fan drive motor 180b is set lower than the cooling acceleration speed. The rotational speed of the fan drive motor 180b when the steering assist is released may be zero.
[0035]
The cooling air blowing mechanism 180 has a pipe 190 that guides air introduced from the outside of the vehicle into the vehicle during traveling to the fins 175, and the pipe 190 is supported by the vehicle body side via the bracket 181. . Other configurations of this comparative example are the same as those of the first embodiment.
[0036]
According to the comparative example , the heat generated by the control device 160 is conducted to the fins 175 and is radiated from the fins 175 to the air. At this time, since the cooling air is blown to the fins 175 by the fan 180a driven by the motor 180b, heat can be efficiently radiated. In addition, since the fan drive motor 180b is controlled so as to have a cooling acceleration speed at the time of steering assistance and to be lower than the cooling acceleration speed at the time of steering assistance release, the cooling air at the time of steering assistance when the heat generated by the control device 160 increases. The amount can be increased. Thereby, cooling can be performed efficiently. Furthermore, air introduced into the vehicle from outside the vehicle during traveling can also be blown onto the fins 175 as cooling air, so that cooling can be performed efficiently.
[0037]
(1) and (2) of FIG. 9 show a second embodiment of the present invention. Hereinafter, differences from the first embodiment will be described, and the same parts are denoted by the same reference numerals. In the first embodiment, the heat generated by the control device is radiated into the oil. Instead, in the second embodiment, the heat is radiated into the air. That is, the control device 260 includes a substrate 260 ′ provided with a control circuit and a drive circuit similar to those in the first embodiment, and a box-shaped casing 260 ″ covering the substrate 260 ′. A plurality of plate-like heat radiation fins 275 are attached to the outside of the side wall closest to the substrate 260 ′ in the casing 260 ″. A mechanism 280 for blowing cooling air is provided on the fin 275 as indicated by an arrow in FIG.
[0038]
The cooling air blowing mechanism 280 has pipes 276 a and 276 b that guide air discharged from the covers 46 a and 46 b covering the rack 8 when the volumes of the covers 46 a and 46 b are reduced to the fins 275. That is, the pipes 276a and 276b are fixed to the vehicle body side, and one end is connected to the vent holes 43 "and 10b" as shown by a two-dot chain line in FIGS. 2 and 3, and the other end is shown in FIG. As shown, it is disposed at a position facing the fins 275. Filters 277a and 277b are provided in the middle of the respective pipes 276a and 276b to prevent dust from entering the covers 46a and 46b. Others are the same as in the first embodiment.
[0039]
According to the second embodiment, the heat generated by the control device 260 is conducted to the fins 275 and is radiated from the fins 275 to the air. At this time, since cooling air is blown to the fins 275, heat can be radiated efficiently. Furthermore, the cooling air can be blown to the fins 275 by using the movement of the rack 8 at the time of steering, and the cooling air is blown at the time of steering when the heat generation of the control device 260 becomes large, so that the cooling is performed efficiently. be able to.
In the second embodiment, as in the comparative example , a pipe for guiding the cooling air introduced from the outside of the vehicle into the vehicle during traveling to the fins 275 may be provided.
[0040]
The present invention is not limited to the above embodiment. For example, a torque sensor that detects steering torque may be provided instead of the steering angle sensor 51, and the presence or absence of steering may be determined based on the value of the steering torque. Further, the conditions for performing the steering assistance and the conditions for releasing the steering assistance are not particularly limited. For example, the steering assistance conditions can be satisfied when the direction indicator is operated. The present invention can also be applied to a ball screw type power steering apparatus.
[0041]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the power steering apparatus which can cool the control apparatus of the drive motor of the pump which discharges the pressure oil for steering assistance force generation | occurrence | production reliably and efficiently can improve control stability.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a power steering apparatus according to an embodiment of the present invention. FIG. 2 is a partially broken front view of the power steering apparatus according to the embodiment of the present invention. FIG. 4 is a sectional view taken along line IV-IV in FIG. 1. FIG. 5 is a front sectional view of a main part of the power steering apparatus according to the first embodiment of the present invention, and FIG. , (3) is a cross-sectional view. FIG. 6 is a perspective view showing a modified example of the piping of the power steering apparatus according to the embodiment of the present invention. FIG. 7 is a schematic view of the power steering apparatus according to the modified example of the first embodiment of the present invention. (1) is a front sectional view, (2) is a side sectional view, (3) is a flat sectional view. FIG. 8 (1) is a front view of a main part in a power steering device of a comparative example of the present invention. 2) the power steering of a second embodiment of a plan view the present invention; FIG (1) is a front view of a main part of grayed device (2) is a plan view EXPLANATION OF REFERENCE NUMERALS
1 Power steering device 18 Hydraulic cylinder (hydraulic actuator)
37 Pump 46a, 46b Cover 50 Motor 60 Controller 71 Tank 72a Inlet 72b Outlet 74 Heat absorption part 75, 75 ', 175, 275 Fin 180, 280 Cooling air blowing mechanism 180b Fan drive motor 190 Piping 276a, 276b Piping

Claims (3)

A tank,
A pump for circulating the oil in the tank;
An electric motor that drives the pump;
A hydraulic actuator that generates a steering assist force based on the pressure of the oil discharged from the pump;
In a power steering device for a vehicle, including a control device that sets a rotation speed of the motor to a steering assist speed at the time of steering assist and a standby speed that is lower than the steering assist speed at the time of steering assist release.
The tank has a metal heat absorption part having thermal conductivity, and a metal heat radiation fin integrated with the heat absorption part,
The heat absorption part is joined to the control device so as to allow heat conduction from the control device to the heat absorption part,
The fins are arranged to be immersed in the oil in the tank ;
The power steering device according to claim 1, wherein the fin is disposed at a position in contact with an oil flow from the inlet to the outlet in the tank, and has a streamline shape so that the oil flows smoothly . A tank,
A pump for circulating the oil in the tank;
An electric motor that drives the pump;
A hydraulic actuator that generates a steering assist force based on the pressure of the oil discharged from the pump;
A control device that sets the rotation speed of the motor to a steering assist speed at the time of steering assist and a standby speed that is lower than the steering assist speed at the time of steering assist release;
A pinion rotating by steering,
A rack meshing with the pinion,
A housing covering the rack;
In a power steering device comprising a cover that covers a rack protruding from the housing,
The control device has a heat dissipation fin,
A cooling air blowing mechanism for blowing cooling air to the fins is provided,
The rudder angle is changed by the movement of the rack by the rotation of the pinion,
The cover can be expanded and contracted so that the volume increases and decreases as the rack moves.
The cooling air blowing mechanism has a pipe for guiding the air discharged from the cover when the volume is reduced to the fins,
The piping is provided outside the housing and the cover,
One end of the pipe is connected to a vent hole communicating with the inside of the housing and the cover, and the other end of the pipe is disposed at a position facing the fin . The power steering apparatus according to claim 2, wherein the cooling air blowing mechanism includes a pipe that guides air introduced into the vehicle from outside the vehicle to the fins during traveling .

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