JP2007224872A - Pump device and power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pump device inhibiting the deterioration of torque transmission efficiency even if a pump rotation shaft is set horizontally. <P>SOLUTION: The pump device includes a pump housing, a drive shaft rotatably supported by the pump housing, an inner rotor driven and rotated by the drive shaft and including external teeth, an outer rotor including inner teeth meshing with the external teeth of the inner rotor and a drive source driving and rotating the drive shaft. The drive shaft is arranged roughly perpendicularly to the vertical direction and a meshing part having the minimum pump volume of a plurality of pump chambers formed between the inner rotor and the outer rotor is arranged at a roughly vertical direction upper side. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pump of a power steering device that assists steering force.

Conventionally, in the gear pump disclosed in Patent Document 1, the trochoid pump is driven by an electric motor. An internal gear pump such as a trochoid pump transmits torque from the inner rotor to the outer rotor at a meshing position where the pump volume is minimized, and management of meshing accuracy is important.
JP-A-5-202861

  However, in the above prior art, when the rotary shaft of the pump is horizontal, the outer rotor fitted between the cam ring and the inner rotor falls down vertically within the clearance. When the engagement between the inner rotor and the outer rotor deviates from an appropriate positional relationship due to this drop, there is a problem that the torque transmission efficiency is reduced when the pump is started.

  The present invention has been made paying attention to the above problems, and an object of the present invention is to provide a pump device that suppresses a decrease in torque transmission efficiency even when the pump rotating shaft is horizontal.

  To achieve the above object, according to the present invention, a pump housing, a drive shaft that is rotatably supported by the pump housing, an inner rotor that is rotationally driven by the drive shaft and has external teeth, and external teeth of the inner rotor In the pump device having an outer rotor having internal teeth meshing with each other and a drive source for rotationally driving the drive shaft, the drive shaft is disposed substantially perpendicular to the vertical direction, and between the inner rotor and the outer rotor. Among the plurality of pump chambers, the meshing portion having the minimum pump volume is arranged almost on the upper side in the vertical direction.

  Therefore, it is possible to provide a pump device that suppresses a decrease in torque transmission efficiency even when the pump rotation shaft is in the horizontal direction.

  Hereinafter, the best mode for realizing the pump device and the power steering device of the present invention will be described based on the embodiments shown in the drawings.

[System configuration of power steering system]
Example 1 will be described with reference to FIGS. FIG. 1 is a system configuration diagram of a power steering device to which the present pump device is applied. When the driver steers the steering wheel 2 (steering wheel), the pinion 4 is driven through the shaft 3, and the rack 5 moves in the axial direction by a so-called rack and pinion mechanism (steering mechanism) to steer the front wheels. The shaft 3 is provided with a torque sensor 6 (steering torque detecting means) for detecting the steering torque of the driver, and outputs a torque signal to the control unit 7 (electric motor control circuit).

  The rack 5 is provided with a power steering mechanism that assists the movement of the rack 5 in accordance with the steering torque of the driver. The power steering mechanism is provided with a motor M (drive source or electric motor) provided with a position sensor 9, a reversible pump 1, and a cylinder 8 (hydraulic power cylinder) that moves the rack 5 to the left and right. A piston 83 that is movable in the axial direction is provided inside the cylinder 8, and the piston 83 defines first and second cylinder chambers 81 and 82 (pressure chambers).

  The first cylinder chamber 81 is connected to the first passage P, and the first passage P is connected to the pump 1. The second cylinder chamber 82 is connected to the second passage S, and the second passage S is connected to the pump 1.

  In addition to the torque signal from the torque sensor 6, the control unit 7 receives a switch signal from the ignition switch, an engine speed signal from the engine speed sensor, a vehicle speed signal from the vehicle speed sensor, and the like. The steering assist force is determined to output a command signal to the motor M.

  Further, the control unit 7 switches the stop / rotation of the motor M and the rotation direction according to the vehicle running state. When the pump 1 is stopped / rotated and the direction of rotation is changed, the change in the pump pressure affects the outer rotor 30. By making the pump 1 into an appropriate meshing state, the response of the pump discharge pressure is improved and the steering response It enhances sex.

[Details of pump]
(Front view and sectional view)
2 is a front view of the pump 1 in the x-axis negative direction side, and FIG. 3 is a front view of the y-axis positive direction side. 4 is a partial cross-sectional view in the x-axis positive direction, and FIG. 5 is a front view in the y-axis direction with the second housing 20 removed.

  The axial motor M side of the pump 1 is the positive y-axis direction, the direction orthogonal to the y-axis and going from the suction port 210 to the discharge port 220 is the positive x-axis direction, orthogonal to the x and y axes, and from the drive shaft 50 to the reservoir tank. The side toward RSV is the z-axis positive direction. 5 is a straight line that passes through the axis O of the drive shaft 50 and is parallel to the z-axis.

  The pump 1 includes a housing 10, an inner rotor 40, an outer rotor 30, a drive shaft 50, and a cam ring 60. A motor M is provided on the negative side of the pump 1 in the y-axis direction, and a reservoir tank RSV is provided on the positive side of the z-axis.

  The drive shaft 50 is provided in parallel to the y axis, and the inner rotor 40 and the outer rotor 30 rotate in parallel to the z axis (vertical direction). In addition, a relief valve Ref / V is provided on the negative z-axis side of the pump 1, and when the pump pressure exceeds a predetermined value, the pressure is released to the reservoir tank RSV.

  The cam ring 60 is an annular member, and is accommodated inside the first and second housings 10 and 20 so that the outer rotor 30 is rotatably accommodated therein. On the other hand, the inner rotor 40 is supported by the drive shaft 50 and is accommodated on the inner periphery of the outer rotor 30.

  A first suction port 110 is provided in a region on the negative side in the negative direction of the y axis of the first housing 10 and on the negative side in the negative direction of the x axis from the II line (see FIG. 5). Is provided with a first discharge port 120. Similarly, second suction and discharge ports 210 and 220 are provided on the side surface 21 of the second housing 20 in the positive direction of the y axis and in the negative and positive direction of the x axis with respect to the II line.

  The outer rotor 30 has an internal gear 310 on the inner periphery, and the outer peripheral surface 320 and the cam ring 60 are accommodated so as to be relatively rotatable, and the internal gear 310 and a part of the external gear 410 of the inner rotor 40 mesh with each other. .

  The internal gear 310 and the external gear 410 are provided at the same pitch, and the number of teeth of the internal gear 310 is one more than the number of teeth of the external gear 410. The number of teeth of the internal gear 310 may be two or more with respect to the number of teeth of the external gear 410 and is not particularly limited.

  Since the number of teeth of the internal gear 310 is one more than the number of teeth of the external gear 410, the internal gear 310 and the external gear 410 mesh with each other eccentrically. Due to this eccentricity, the center O of the inner rotor 40 is shifted to the y-axis positive direction side with respect to the center O ′ of the outer rotor 30, and a pump chamber 500 separated by the internal gear 310 and the external gear 410 is formed.

  Due to the eccentricity of the outer rotor 30 and the inner rotor 40, the internal gear 310 and the external gear 410 mesh closely with each other toward the z-axis positive direction and completely mesh with each other at the meshing portion A that is the end in the z-axis positive direction. The pump chamber 500 has a minimum volume.

  The meshing portion A is located above the rotational center O ′ of the outer rotor 30 in the vertical direction (z-axis direction) and is disposed substantially above the vertical direction. In the embodiment of the present application, the meshing portion A is located on the most positive z-axis direction side of the inner rotor 40 and on the II line.

  Further, the meshing is disengaged toward the z-axis negative direction, and the meshing is completely disengaged at the closed position B which is the end portion in the z-axis negative direction, so that the maximum pump volume is obtained. The clearance between the internal gear 310 and the external gear 410 at the closed position B is provided to be substantially zero while avoiding contact.

  Here, the inner rotor 40 is pivotally supported by the drive shaft 50, and the position in the z-axis direction is fixed. On the other hand, since the outer rotor 30 is accommodated so as to be rotatable with respect to the cam ring 60, a clearance exists between the outer periphery 320 and the cam ring inner periphery 61, and the position in the z-axis direction is not fixed.

  Therefore, when the inner rotor 40 and the outer rotor 30 are provided parallel to the vertical direction as in the present embodiment, gravity Fg in the negative z-axis direction acts on the outer rotor 30 and attempts to move in the negative z-axis direction by the clearance. To do. Since the meshing portion A is disposed substantially upward in the vertical direction, the outer rotor 30 is thereby supported by the inner rotor 40 at the meshing portion A.

  Further, the II straight line parallel to the z-axis (vertical direction) passes through the meshing portion A where the outer teeth 410 of the inner rotor 40 and the inner teeth 310 of the outer rotor 30 mesh most closely. In FIG. 5, the meshing portion A is between the inner teeth 310 located on both sides of the external tooth 410, but the meshing portion A also moves in the counterclockwise direction as the drive shaft 50 rotates counterclockwise. And move between the external teeth 410 located on both sides of the internal teeth 310.

  For this reason, the I-I straight line is located between the inner teeth 310 located on both sides of the outer teeth 410 or between the outer teeth 410 located on both sides of the inner teeth 310.

  Therefore, the gravity Fg and the drag N of the inner rotor 40 against the outer rotor 30 are vectors in opposite directions, and both the Fg and N are on the same vertical line, so that the outer rotor 30 is suspended by the inner rotor 40 at the meshing portion A. It will be in the state. Thereby, the meshing property is improved.

  Further, the meshing portion A is located above the rotational center O ′ of the outer rotor 30 in the vertical direction (z-axis direction). Therefore, when the outer rotor 30 sinks in the negative z-axis direction, the outer rotor 30 reliably contacts the inner rotor 40 at the meshing portion A.

  For this reason, the outer rotor 30 is biased by the inner rotor 40 by the gravity Fg, the pump volume in the meshing portion A is reduced, and the external teeth 410 and the internal teeth 310 mesh closely. Therefore, in the meshing portion A, the separation between the inner rotor 40 and the outer rotor 30 is suppressed, and the meshing efficiency is improved. Since the state in which the outer teeth 410 and the inner teeth 310 are closely meshed with each other is continued even before and after the pump is started, the outer teeth 140 do not collide with the inner teeth 310, and sound vibration is reduced.

  The first and second suction ports 110 and 210 and the first and second discharge ports 120 and 220 are provided at positions corresponding to the pump chamber 500 in the first and second housings 10 and 20, respectively. Each of the suction ports 110 and 210 and each of the discharge ports 120 and 220 is a crescent-shaped recess that is symmetrical with respect to the line III-III, and communicates with the passages P and S to supply and discharge oil to the pump chamber 500.

  When the inner rotor 40 and the outer rotor 30 are rotated counterclockwise, in the x-axis negative direction side region (corresponding to the first and second suction ports 110 and 210 side) with respect to the III-III straight line in the pump chamber 500, the rotation occurs. Thus, the suction area 510 in which the volume increases and the discharge area 520 in which the volume decreases with rotation in the x-axis positive direction side area (corresponding to the first and second discharge ports 120 and 220 side). When rotating clockwise, suction and discharge are reversed.

  A drive shaft 50 provided in parallel with the y-axis is connected to the motor M to drive the inner rotor 40. As the inner rotor 40 and the outer rotor 30 mesh with each other, the outer rotor 30 is driven to rotate as the drive shaft 50 and the inner rotor 40 rotate. The pump 1 functions as a bidirectional pump by rotating the drive shaft 50 forward and backward.

  Further, the suction and discharge ports 110 and 120 in the first housing 10 are respectively provided with a suction side and discharge side communication grooves 111 and 121 (discharge pressure introduction passages) extending in the x-axis negative and positive directions. The suction-side and discharge-side communication grooves 111 and 121 are provided on the y-axis negative direction side with respect to the rotation center O of the drive shaft 50 and communicate with the clearance D between the cam ring 60 and the outer rotor 30 and the suction and discharge ports 110 and 120. Then, the hydraulic pressures of the suction and discharge ports 110 and 120 are introduced into the z-axis negative direction side region D1 of the clearance D.

(Disassembled perspective view)
FIG. 6 is an exploded perspective view. A radial discharge pressure introducing groove 62 is provided in the inner periphery 61 of the cam ring 60. The discharge pressure introduction groove 62 is provided in a donut-shaped cam ring 60 over a predetermined angle range on the z-axis negative direction side. In the embodiment of the present application, at least at the time of assembly, the suction side and discharge side communication grooves 111 and 121 are provided in an angular range where they can communicate with each other.

  Therefore, when the pump is driven, the discharge pressure is introduced into the discharge pressure introduction groove 62 from either the suction side or the discharge side communication grooves 111 and 121 regardless of the rotation direction of the pump 1. Accordingly, a discharge pressure is always introduced into the z-axis negative direction region D1 of the clearance D provided between the outer rotor 30 and the cam ring 60, and the outer rotor 30 is urged in the z-axis positive direction by this discharge pressure. .

  For this reason, when the pump is driven, gravity Fg in the negative z-axis direction acts on the outer rotor 30, and a biasing force Fp in the positive z-axis direction due to the discharge pressure in the region D1 acts (see FIG. 5). . By this urging force Fp, the z-axis negative direction force applied to the outer rotor 30 is relaxed, the surface pressure between the outer rotor 30 and the inner rotor 40 at the meshing portion A is prevented from becoming too high, and meshing friction is reduced. Plan.

  Further, since the discharge pressure introducing groove 62 is provided over a predetermined angle range on the z-axis negative direction side in the cam ring inner periphery 61, the outer rotor outer peripheral surface 320 is on the z-axis negative direction side (vertically below the discharge-side communication grooves 111 and 121). The discharge pressure is applied over the entire area of the side.

  Accordingly, the outer rotor 30 is urged uniformly from the z-axis negative direction side to the left and right (x-axis direction), the clearance of the confinement portion B is reduced to reduce leakage, and the confinement property is improved. Further, since the left and right are uniform, the meshing property of the meshing part A is also improved.

  Further, axial grooves 63 are provided at both ends of the discharge pressure introduction groove 62, and the suction side and discharge side communication grooves 111, 121 and the discharge pressure introduction groove 62 are connected to positively connect the discharge pressure introduction groove 62. Introduce discharge pressure.

[Contrast of the effects of the conventional example and the embodiment of the present application]
7 and 8 are enlarged views of the vicinity of the meshing portion A. FIG. FIG. 7 shows a conventional example, and FIG. 8 shows the present application. In both the conventional example and the present application, it is assumed that the inner rotors 40 and 40 'and the outer rotors 30 and 30' rotate in the counterclockwise direction.

  In the conventional example, the meshing portion A ′ is located at the end in the positive x-axis direction of the outer rotor 30 ′. Therefore, the gravity Fg against the outer rotor 30 ′ and the drag N ′ of the inner rotor 40 are not vectors on the same straight line.

  Therefore, the inner teeth 310 ′ of the outer rotor 30 ′ slide along the tooth surfaces of the inner rotor outer teeth 410 ′ by the x-axis positive direction component N′x + of the drag N ′, and the outer rotor 30 ′ is in contact with the cam ring 60 ′. It falls down vertically within the clearance.

  Due to this depression, the meshing between the inner rotor 40 ′ and the outer rotor 30 ′ deviates from an appropriate positional relationship, the inner rotor 40 and the outer rotor 30 are separated from each other, and the pump volume at the meshing portion A ′ is expanded.

  In FIG. 7, the meshing portion A ′ is located at the end in the positive x-axis direction of the inner rotor 40 ′, so that the outer rotor 30 falls vertically downward and the z-axis negative side surface of the inner rotor outer teeth 410 and the z of the outer rotor inner teeth 310. The axial positive side surface is separated. That is, in the meshing portion A ′, the tooth surface 411 ′ on the counterclockwise direction side of the inner rotor outer tooth 410 ′ and the tooth surface 311 ′ of the outer rotor inner tooth 310 ′ facing the tooth surface 411 ′ are separated from each other.

  Therefore, the torque transmission efficiency is reduced, and the external tooth surface 411 ′ and the internal tooth surface 311 ′ separated by the counterclockwise rotation of the inner rotor 40 ′ before the pump start collide with each other when the pump start is started. There was a problem that sound vibration occurred. In particular, in the pump of a power steering device, the sound vibration at the time of starting deteriorates the steering feeling, so the problem of sound vibration becomes significant.

  (1) On the other hand, in this embodiment, the pump housing 10, the drive shaft 50 rotatably supported by the pump housing 10, the inner rotor 40 that is rotationally driven by the drive shaft 50 and has external teeth 410, and the inner rotor 40 In the pump 1 having the outer rotor 30 having the inner teeth 310 that mesh with the outer teeth 410 and the motor M that rotationally drives the drive shaft 50, the drive shaft 50 is disposed substantially horizontally, and the inner rotor 40 and the outer rotor 30 are separated from each other. Among the plurality of pump chambers 500 formed therebetween, the meshing portion A having the minimum pump volume is arranged substantially on the upper side in the vertical direction.

  Thus, even when the outer rotor 30 moves in the z-axis negative direction by the clearance due to gravity, the gravity Fg and the drag N are set to vectors substantially in the vertical direction (z-axis direction) at the meshing contact A1. Is possible. Therefore, the meshing property can be improved and the torque transmission efficiency can be improved.

  Further, the tooth surfaces 310 and 410 of the meshing portion A are closely meshed, and the tooth surface 411 on the counterclockwise direction side of the inner rotor outer tooth 410 and the tooth surface 311 facing the tooth surface 411 in the outer rotor 30 are not separated. The vibration of the tooth surfaces 311 and 411 can be avoided along with the rotation to reduce the sound vibration.

  (2) The inner rotor 40 and the outer rotor 30 are provided substantially in parallel with the vertical axis, and the vertical line (z-axis direction) II line passing through the rotation center O of the drive shaft 50 corresponds to both the external teeth 410. It was decided to be located between the inner teeth 310 located on the sides or between the outer teeth 410 located on both sides of the inner teeth 310.

  As a result, the gravity Fg and the drag N can be almost certainly set as vectors in the vertical direction, and the torque transmission efficiency can be further improved.

  (3) In the pump chamber 500, the meshing portion A having the minimum pump volume is positioned above the rotation center O ′ of the outer rotor 30 in the vertical direction (z-axis direction).

  As a result, when the outer rotor 30 sinks in the negative z-axis direction, a drag force N of gravity Fg acts on the outer rotor 30 from the inner rotor 40 at the contact point A1, and the outer rotor 30 is urged and meshed with the inner rotor 40 by the gravity Fg. It becomes possible to reduce the pump volume in the part A.

  Therefore, the pump volume is prevented from expanding in the meshing portion A, the separation between the inner rotor 40 and the outer rotor 30 is suppressed, and the external teeth 410 and the internal teeth 310 are closely meshed to improve the meshing efficiency. Can do.

  (4), (5), (6) A hydraulic power cylinder 8 for assisting the steering force of the rack 5 and the pinion 4 connected to the steering wheel 2, and a pump for supplying hydraulic pressure to the pressure chamber of the hydraulic power cylinder 8 A motor M that drives the pump 1, a torque sensor 6 that detects the steering torque of the rack 5 and the pinion 4, and an ECU 7 that outputs a drive command signal to the motor M based on the steering torque detected by the torque sensor 6. The present pump 1 is applied to a power steering apparatus equipped with

Thereby, also in a hydraulic power steering device, the same operation effect as the above (1), (2), and (3) can be obtained.
(Other examples)

  The best mode for carrying out the present invention has been described based on the embodiments. However, the specific configuration of the present invention is not limited to each embodiment, and the scope of the invention is not deviated. Design changes and the like are included in the present invention.

  Further, technical ideas other than the claims that can be grasped from the above embodiments will be described below together with the effects thereof.

(A) In the pump device according to claim 1,
Of the plurality of pump chambers, a discharge pressure introduction groove for introducing discharge pressure is formed between the outer peripheral surface of the outer rotor on the closed position side having the largest pump volume and the inner peripheral surface of the housing facing the outer peripheral surface. The pump device characterized by being made.

  The cam ring is reduced by guiding discharge pressure to the lower side in the vertical direction of the outer periphery of the cam ring against the downward drop of the cam ring due to gravity. Therefore, it is possible to avoid an excessive increase in the surface pressure at the meshing portion between the inner rotor and the outer rotor, and it is possible to improve meshing properties and reduce friction between the outer periphery of the outer rotor and the housing.

(B) In the pump device according to (a) above,
The pump device according to claim 1, wherein the discharge pressure introduction path is a groove formed on an inner peripheral surface of the housing and in a circumferential direction over a predetermined angle range.

  By introducing the discharge pressure into the groove extending in the circumferential direction, the outer rotor can be pushed up uniformly in the range of the groove from the lower side in the vertical direction, and the closeability of the closed portion can be improved.

(C) In the pump device described in (b) above,
The pump device according to claim 1, wherein the discharge pressure introduction groove is formed from the lower side in the vertical direction to both sides in the circumferential direction over the same angle range.

  Since the force that pushes up the outer rotor from the lower side in the vertical direction is uniform in the left-right direction, errors in confinement and meshing characteristics due to the rotation direction can be suppressed.

(D) In the pump device described in (b) above,
The pump device according to claim 1, wherein the discharge pressure introduction groove further includes an axial groove that is an inner peripheral surface of the housing and connects the discharge pressure introduction groove and the pump chamber.

  By connecting the discharge pressure introducing groove and the discharge pressure introducing groove, the discharge pressure can be positively introduced into the groove.

(E) In the power steering device according to claim 4,
The power steering device according to claim 1, wherein the electric motor switches between stop and rotation according to a vehicle running state.

  When the rotation is started from the pump stop state, the pump is in an appropriate meshing state, so that the response of the pump discharge pressure is improved and the steering response can be improved.

(F) In the power steering device described in (e) above,
The power steering device according to claim 1, wherein the electric motor switches a rotation direction according to a vehicle running state.

  The rotation direction of the pump is also switched along with the switching of the rotation direction of the electric motor. At the time of this switching, the high pressure side and low pressure side of the pump are switched, so the outer rotor is also affected, but since the pump is in an appropriate meshing state, the switching responsiveness in the pump rotation direction is improved, Steering response can be improved.

It is a system configuration diagram of a power steering device to which the present pump device is applied. It is a x-axis negative direction side front view of a pump. It is the y-axis positive direction side front view of a pump. It is a x-axis positive direction partial sectional view of a pump. It is a y-axis direction front view of the pump which removed the 2nd housing. It is a disassembled perspective view of a pump. It is an enlarged view of the meshing part vicinity in a prior art example. It is an enlarged view of the meshing part vicinity in this application.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pump 2 Steering wheel 3 Shaft 4 Pinion 5 Rack 6 Torque sensor 7 Control unit 8 Hydraulic power cylinder 9 Position sensor 10 Pump housing 11 Y-axis negative side surface 20 Second housing 21 Y-axis positive side surface 30 Outer rotor 40 Inner rotor 50 Drive shaft 60 Cam ring 61 Inner circumference 62 Discharge pressure introduction groove 63 Axial groove 81, 82 First, second cylinder 83 Piston 110, 210 First, second suction port 120, 220 First, second discharge port 111, 121 Suction, Discharge side communication groove 310 Inner tooth 311 Tooth surface 320 Outer surface 400 Inner rotor 410 Outer tooth 411 Tooth surface 500 Pump chamber 510 Suction region 520 Discharge region A Engagement portion B Closed portion Ref / V Relief valve RSV Reservoir tank

Claims (6)

A pump housing;
A drive shaft rotatably supported by the pump housing;
An inner rotor that is rotationally driven by the drive shaft and has external teeth;
An outer rotor having inner teeth that mesh with outer teeth of the inner rotor;
A pump device having a drive source for rotationally driving the drive shaft,
The drive shaft is arranged substantially horizontally;
A pumping device characterized in that, among a plurality of pump chambers formed between the inner rotor and the outer rotor, a meshing portion having a minimum pump volume is disposed substantially upward in the vertical direction. A pump housing;
A drive shaft rotatably supported by the pump housing;
An inner rotor that is rotationally driven by the drive shaft and has external teeth;
An outer rotor having inner teeth that mesh with outer teeth of the inner rotor;
A pump device having a drive source for rotationally driving the drive shaft,
The drive shaft is arranged substantially horizontally;
The inner rotor and outer rotor are provided substantially parallel to a vertical axis,
The vertical axis passing through the rotation center of the drive shaft is a meshing portion where the outer teeth of the inner rotor and the inner teeth of the outer rotor are most closely meshed with each other, and the inner teeth located on both sides of the outer teeth. It is located between teeth or between the external teeth located on both sides of the internal teeth. A pump housing;
A drive shaft rotatably supported by the pump housing;
An inner rotor that is rotationally driven by the drive shaft and has external teeth;
An outer rotor having inner teeth that mesh with outer teeth of the inner rotor;
A pump device having a drive source for rotationally driving the drive shaft,
The drive shaft is arranged substantially horizontally;
The inner rotor and outer rotor rotate substantially parallel to the vertical axis;
Among the plurality of pump chambers formed between the inner rotor and the outer rotor, a meshing portion having a minimum pump volume is positioned above the rotation center of the outer rotor in the vertical direction. . A hydraulic power cylinder for assisting the steering force of the steering mechanism connected to the steering wheel;
A pump for supplying hydraulic pressure to the pressure chamber of the hydraulic power cylinder;
An electric motor for driving the pump;
Steering torque detection means for detecting steering torque of the steering mechanism;
An electric motor control circuit that outputs a drive command signal to the electric motor based on the steering torque detected by the steering torque detecting means;
The pump is
A pump housing;
A drive shaft rotatably supported by the pump housing and connected to the electric motor;
An inner rotor that is rotationally driven by the drive shaft and has external teeth;
An outer rotor having inner teeth that mesh with the outer teeth of the inner rotor,
The drive shaft is arranged substantially horizontally;
The power steering device according to claim 1, wherein among the plurality of pump chambers formed between the inner rotor and the outer rotor, a meshing portion having a minimum pump volume is disposed substantially upward in the vertical direction. A hydraulic power cylinder for assisting the steering force of the steering mechanism connected to the steering wheel;
A pump for supplying hydraulic pressure to the pressure chamber of the hydraulic power cylinder;
An electric motor for driving the pump;
Steering torque detection means for detecting steering torque of the steering mechanism;
An electric motor control circuit that outputs a drive command signal to the electric motor based on the steering torque detected by the steering torque detecting means;
The pump is
A pump housing;
A drive shaft rotatably supported by the pump housing and connected to the electric motor;
An inner rotor that is rotationally driven by the drive shaft and has external teeth;
An outer rotor having inner teeth that mesh with the outer teeth of the inner rotor,
The drive shaft is arranged substantially horizontally;
The inner rotor and outer rotor are provided substantially parallel to a vertical axis,
The vertical axis passing through the rotation center of the drive shaft is a meshing portion where the outer teeth of the inner rotor and the inner teeth of the outer rotor are most closely meshed with each other, and the inner teeth located on both sides of the outer teeth. The power steering device is located between teeth or between the outer teeth located on both sides of the inner teeth. A hydraulic power cylinder for assisting the steering force of the steering mechanism connected to the steering wheel;
A pump for supplying hydraulic pressure to the pressure chamber of the hydraulic power cylinder;
An electric motor for driving the pump;
Steering torque detection means for detecting steering torque of the steering mechanism;
An electric motor control circuit that outputs a drive command signal to the electric motor based on the steering torque detected by the steering torque detecting means;
The pump is
A pump housing;
A drive shaft rotatably supported by the pump housing and connected to the electric motor;
An inner rotor that is rotationally driven by the drive shaft and has external teeth;
An outer rotor having inner teeth that mesh with the outer teeth of the inner rotor,
The drive shaft is arranged substantially horizontally;
The inner rotor and outer rotor rotate substantially parallel to the vertical axis;
Of the plurality of pump chambers formed between the inner rotor and the outer rotor, a meshing portion having a minimum pump volume is positioned above the rotation center of the outer rotor in the vertical direction. apparatus.

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