JPH09224361A - Power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a steering device which can perform optimum power assistance by outputting specific output torque according to vehicle driving state to a steering output shaft. SOLUTION: In an armature 36 of a motor part provided in a power steering device, brushes 76 and 78 are rotatably retained and a contact state for the armature 36 is changed due to rotation according to, for example, vehicle speed. When the brushes 76 and 78 rotate, the coil wire of the armature 36 is partially short-circuited, the practically effective length of the coil wire of the armature 36 is modified, and drive force at the motor changes. Therefore, by rotating the brushes 76 and 78 according to the driving state of the vehicle, specific output torque according to the driving state of the vehicle is outputted to a steering output shaft, thereby being able to perform an optimum power assistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power steering system in which a motor performs power assist based on an input torque from a steering input shaft (generates an auxiliary driving force) and outputs a predetermined output torque to a steering output shaft. Related to the device.

[0002]

2. Description of the Related Art In an electric power steering apparatus using a motor, a means for changing a power supply frequency and a power supply voltage is used to control an output generated by the motor. Circuits are indispensable and costly. Therefore, a so-called actual air gap type electric motor capable of solving such a defect has been proposed (for example, Japanese Patent Application Laid-Open No. 53-47908).

[0003] In this electric motor, there are provided first and second stators having windings through which an alternating current flows, and a rotor is arranged between the first and second stators. Further, the opposed positions of the first and second stators can be relatively changed by manual adjustment. According to this motor, the phase of the torque generated by the first stator and the rotor and the phase of the torque generated by the second stator and the rotor are changed by manually changing the facing positions of the first and second stators. Is changed (variable phase type), whereby the output torque of the rotor (rotating shaft) can be adjusted to obtain an arbitrary output. Therefore, an electronic circuit or the like having a complicated configuration for torque control is not required, and the cost is reduced with a simple structure.

By the way, in a power steering apparatus (power steering) for a vehicle, it is desirable to change the power assist force according to the vehicle running state such as vehicle speed and steering angle. In this respect, the electric motor disclosed in the above publication has a structure in which the output torque of the rotor (rotating shaft) is adjusted by manually moving the first or second stator, and therefore, the electric motor using this electric motor as it is. In the power steering apparatus, the power assist force cannot be changed according to the input torque from the steering input shaft, the vehicle speed, the steering angle, etc., that is, the power assist according to the vehicle running state is performed to obtain a predetermined output torque. There was a drawback that it could not output to the steering output shaft.

[0005]

SUMMARY OF THE INVENTION In consideration of the above facts, the present invention provides a power steering apparatus capable of outputting a predetermined output torque corresponding to a running state of a vehicle to a steering output shaft to perform optimum power assist. The purpose is to obtain.

[0006]

A power steering apparatus according to a first aspect of the present invention is a motor comprising an armature and first and second magnetic pole pieces provided on opposite sides of the armature. In the power steering apparatus, which performs power assist based on an input torque from a steering input shaft connected to a steering wheel and outputs a predetermined output torque to a steering output shaft for steering a steered wheel, An energization switching mechanism that switches the energization direction of the motor to the power supply brush according to the left-right rotation direction of the input shaft, and the contact state of the power supply brush with the armature according to the running state of the vehicle, and the motor And output torque control means for controlling the power assist force.

In the power steering apparatus according to the first aspect, the motor is connected to a steering input shaft to which a steering wheel is attached and a steering output shaft connected to steered wheels. When the steering input shaft is steered, the energization switching mechanism operates to energize the motor and drive the motor. As a result, the driving force of the motor acts on the steering output shaft, and is applied to the steering output shaft (steered wheels) as an auxiliary driving force. Therefore, the steering input shaft (steering wheel)
Steering force is reduced. Further, when the steering input shaft is switched between left and right, the direction of energization to the motor is switched by the conduction switching mechanism, and the rotation direction of the steering output shaft is switched, so that it is possible to respond to the steering direction of the steering input shaft.

Further, in this power steering apparatus, the output torque control means operates in accordance with the running state of the vehicle to change the contact state of the motor power supply brush with the armature. As a result, the energized state of the armature, that is, the effective effective length of the armature coil is changed, and the driving force of the motor is increased or decreased. That is, by changing the contact state of the power feeding brush with the armature according to the running state of the vehicle,
The power assist force (motor driving force) output to the steering output shaft will increase or decrease in accordance with the running state of the vehicle, and as with the conventional hydraulic power steering device, Based on the power assist, a predetermined output torque can be output to the steering output shaft. Furthermore, the power steering apparatus has a simple structure that does not require a torque sensor, a motor controller, or the like as in the related art, and can significantly reduce the cost and reduce the size and weight.

As described above, in the power steering apparatus according to the first aspect of the present invention, the output torque control means operates in accordance with the traveling state of the vehicle to change the contact state of the power supply brush with the armature, whereby the vehicle travels. The drive control of the motor according to the state is performed, and the steering force can be favorably assisted. Further, the structure is simple, and the cost and the size and weight can be significantly reduced.

A power steering apparatus according to a second aspect of the present invention is the power steering apparatus according to the first aspect, wherein the first magnetic pole piece and the second magnetic pole piece are provided in accordance with the magnitude of the input torque from the steering input shaft. The relative position of the magnetic pole of the is relatively changed around the axis,
It is characterized by comprising magnetic pole control means for controlling the power assisting force of the motor.

In the power steering apparatus according to the second aspect, when the steering input shaft is steered, the magnetic pole control means operates according to the input torque from the steering input shaft, and the first magnetic pole piece and the second magnetic pole piece. The position facing the pole piece is relatively changed around the axis.
In this case, the operation of the magnetic pole control means corresponds to the magnitude of the input torque from the steering input shaft, and the first magnetic pole piece and the second magnetic pole piece are operated.
The position of the magnetic pole piece facing the magnetic pole piece is changed according to the magnitude of the input torque. Therefore, the magnetic flux density (magnetic field strength) of the motor (first and second magnetic pole pieces and armature) changes according to the input torque. For this reason, the power assist force (motor driving force) output to the steering output shaft increases or decreases in proportion to the magnitude of the input torque from the steering input shaft. Similarly, power assist based on the input torque from the steering input shaft can be performed to output a predetermined output torque to the steering output shaft.

A power steering apparatus according to a third aspect of the present invention is the power steering apparatus according to the second aspect, wherein the magnetic pole control means includes one of the first and second magnetic pole pieces and the steering input shaft. And a connecting member for transmitting the swing caused by the left and right rotations of the steering input shaft to move one of the first and second magnetic pole pieces around the axis, and the energization switching mechanism includes: It is characterized in that it is provided integrally with the motor, is connected to the connecting member, and is operated by the connecting member.

In the power steering apparatus according to the third aspect of the invention, the swing caused by the left and right rotations of the steering input shaft is transmitted through the connecting member so that one of the first and second magnetic pole pieces rotates about the axis. Be moved to. Further, the energization switching mechanism provided integrally with the motor is operated by the connecting member. That is, the opposing positions of the first and second magnetic pole pieces are changed and the energization switching mechanism is operated by the connecting member. Therefore, the structure of the device can be simplified.

[0014]

1 to 3 schematically show a power steering apparatus 10 according to an embodiment of the present invention in a schematic sectional view.

The power steering apparatus 10 is used, for example, as an electric power steering apparatus for a vehicle and has an input shaft (steering shaft) 12. The input shaft 12 is arranged in a direction substantially orthogonal to the steered rod 24 as a steering output shaft, supported by a housing 194 by a bearing 192, and a steering wheel (not shown) is attached. The bearing 192 that supports the input shaft 12 is of a self-centering type, and the input shaft 12 can slightly swing about the bearing 192 as a fulcrum. The input shaft 12 has a pinion 196
Is provided and meshes with the rack gear 198 of the steered rod 24 serving as a steering output shaft. In addition, at the tip of the input shaft 12, a holding cylinder 2 that can move to the left and right corresponding to this is provided.
00 is provided, and the holding cylinder 200 further includes
One end of the lever 202 as a connecting member is connected. Therefore, when the input shaft 12 slightly swings around the bearing 192, the lever 202 is moved in the longitudinal direction.

Further, the power steering apparatus 10 includes a motor unit 3
4 is provided. The motor unit 34 is a so-called print motor, and includes an armature 36, and a first magnetic pole piece 38 and a second magnetic pole piece 40 that are provided on opposite sides of the armature 36.
It is composed of A motor rotation shaft 42 is fixed to the center of the armature 36, and the motor rotation shaft 42 is rotatably supported by the housing 16. Armature 36
The motor rotating shaft 42 is provided with a gear 204,
Further, it is connected to a rack gear 210 of the steered rod 24 via a reduction gear 206 and a pinion 208.

On the other hand, the first magnetic pole piece 38 is fixed to the housing 16 so as to face the armature 36. On the other hand, a holding plate 176 is attached to the second pole piece 40, and the holding plate 176 is rotatably mounted on the housing 16.
It is supported by. For this reason, by rotating the second magnetic pole 40 together with the holding plate 176, the position facing the first magnetic pole 38 can be relatively changed around the axis. The holding plate 176 is provided with a gear 212, and the gear 212 is further provided with the lever 20 described above.
2 is engaged with a rack portion 203 formed at the other end. Therefore, the second magnetic pole element 40 is configured to be rotationally moved by moving the lever 202 along the longitudinal direction.

The lever 202 (that is, the input shaft 1
2) In the neutral state, the polarities of the first magnetic pole 38 and the second magnetic pole 40 are the same (N pole-N pole state, or S pole state).
(Pole-S pole state), the length and the like of the lever 202 are set.

Further, the motor section 34 is integrally provided with a limit switch 214 as an energization switching mechanism. As shown in FIG. 4, in the limit switch 214, the operating contact 216 connected to the lever 202 moves to the left and right to come into contact with the fixed contacts 217 and 219, whereby the steering state of the input shaft 12 (the left and right switching state). ) Can be detected. The limit switch 214 is connected to the brush 76 and the brush 78 of the motor unit 34, and can switch the energization direction to the motor unit 34 (armature 36) according to the steering direction of the input shaft 12.

Further, the brush 76 and the brush 78 of the motor section 34 are the moving mechanism section 50 as the output torque control means.
Is held by Here, in FIG. 5, a schematic configuration of the moving mechanism section 50 is shown in a partially cutaway front view. 6 shows a partially broken plan view of the moving mechanism section 50, and FIG. 7 shows a sectional view of the moving mechanism section 50.

In the moving mechanism 50, the brush 76 and the brush 78 are held by the holder 52 so as to be movable in the axial direction. A spring 54 is provided in the holder 52 and constantly urges the brush 76 and the brush 78 in the protruding direction. Further, the holder 52 is rotatably supported by the housing 16 by the bearing 56. Therefore, the brush 76 and the brush 78 can rotate around the axis together with the holder 52. One end of the belt 58 is wound around one end of the holder 52, and the other end of the belt 58 is connected to the operating lever 60. For this reason,
By moving the operating lever 60 in the axial direction, the holder 52, that is, the brush 76 and the brush 78 are rotated, and the contact state with the armature 36 is changed.

The other end of the operating lever 60 is connected to the actuator 62. The actuator 62 is a hydraulic cylinder and can be actuated according to the traveling speed of the vehicle to move the actuating lever 60.

Next, the operation of the present embodiment will be described. In the power steering device 10 having the above-described configuration, when the steering wheel (the input shaft 12) is not steered (the vehicle is in a straight-ahead state), FIG.
As shown in (B), the operating contact 216 of the limit switch 214 has not moved, and the limit switch 214 is in the O position.
In the FF state, the motor section 34 is not energized.

When the steering wheel (input shaft 12) is steered, the motor section 34 is operated according to the steering torque.

That is, when the input shaft 12 is steered to the left or right, the steering force of the input shaft 12 is passed through the pinion 196 and the rack gear 198 when turning to the right as shown by arrow A in FIG. Transmitted to the steering rod 24,
The steered rod 24 is driven in the axial direction (arrow B direction) to steer the steered wheels.

In this case, immediately after the input shaft 12 is steered, the resistance of the steered rod 24 (that is, the tire side) is large, so that the steered rod 24 does not move. Therefore, the input shaft 12 uses the bearing 192 as a fulcrum. It rocks slightly. Therefore, the swing of the input shaft 12 causes the lever 202 to move in the longitudinal direction, and the second magnetic pole element 40 to rotate. As a result, the facing position of the first magnetic pole 38 and the second magnetic pole 40 is relatively changed around the axis, and the polarity of each magnetic pole is in the same polarity state (N pole-N pole state or S pole). (−S pole state) to a different pole state (N pole−S pole state or S pole−N pole state).

Further, at this time, as shown in FIG.
As the lever 202 moves, the operating contact 216 of the limit switch 214 moves, and the limit switch 214 is turned off.
Then, the motor portion 34 (armature 36) is energized and the armature 36 of the motor portion 34 rotates.

As a result, the driving force of the motor section 34 acts on the steered rod 24 to which the motor rotation shaft 42 is connected, and is applied as an auxiliary driving force. Therefore, the steering force of the input shaft 12 (steering wheel) is reduced.

On the other hand, when the input shaft 12 is steered to the left (direction of arrow C in FIG. 2), the steering force of the input shaft 12 is increased by the pinion 1.
It is transmitted to the steered rod 24 through the 96 and the rack gear 198, the steered rod 24 is driven in the axial direction (direction of arrow D), and the steered wheels are steered.

In this case as well, immediately after the steering of the input shaft 12, the steering rod 24 (ie, the tire side) has a large resistance, so the steering rod 24 is immovable.
Slightly swing about the bearing 192 as a fulcrum. For this reason,
The tip portion of the input shaft 12 swings, the lever 202 moves in the longitudinal direction, and the second magnetic pole piece 40 rotates. As a result, the first pole piece 38 and the second pole piece 40
The position facing each other is relatively changed around the axis, and the polarities of the magnetic poles are gradually changed from the same-polarity state to the different-polarity state. Further, at this time, as shown in FIG. 4C, as the lever 202 moves, the operating contact 216 of the limit switch 214 is moved.
However, the limit switch 214 is turned on in the opposite direction to that described above, the motor section 34 (armature 36) is energized, and the armature 36 of the motor section 34 rotates in the opposite direction.

As a result, the driving force of the motor section 34 acts on the steered rod 24 to which the motor rotation shaft 42 is connected, and is applied as an auxiliary driving force. Therefore, the steering force of the input shaft 12 (steering wheel) is reduced.

In this case, the second pole piece 40 and the input shaft 12
The movement of the lever 202 for connecting the first magnetic pole 38 corresponds to the magnitude of the input torque from the input shaft 12.
The opposing position of the second magnetic pole 40 is changed according to the magnitude of the input torque. Therefore, the driving force of the motor unit 34 increases or decreases according to the input torque, and similar to the conventional hydraulic power steering apparatus, power assist based on the input torque from the input shaft 12 is performed to perform a predetermined operation. Output torque can be applied to the steered rod 24.

The steering wheel (input shaft 1
When 2) is switched between left and right, the energization direction of the motor section 34 to the armature 36 is switched by the operation of the lever 202 and the limit switch 214 as described above, and the rotation direction of the motor rotation shaft 42 is switched. Input shaft 12
It can handle the steering direction.

Furthermore, in the power steering apparatus 10, the moving mechanism section 50 operates according to the running state of the vehicle, and the contact state of the brush 76 and the brush 78 of the motor section 34 with the armature 36 is changed. That is, for example, when the vehicle is running at a low speed such as stationary steering, as shown in FIG.
The brush 76 and the brush 78 are in contact with the coil wire of the armature 36 in a substantially parallel state. Therefore, the motor unit 34 generates a predetermined driving force. On the other hand, as the vehicle speed increases, the actuator 62 operates and the operating lever 6
0 is moved axially. As a result, the holder 52, that is, the brush 76 and the brush 78 are rotated, and the armature 3
The contact state with respect to 6 is changed to be in a state substantially orthogonal to the coil wire of the armature 36, as shown in FIG. 8 (B). As a result, the coil wire of the armature 36 is partially short-circuited, and as a result the effective length of the coil wire of the armature 36 is shortened, and the driving force of the motor unit 34 is reduced.

As described above, the contact state of the brush 76 and the brush 78 with the armature 36 is changed according to the running state (vehicle speed) of the vehicle, so that the power assist force (motor portion) applied to the steered rod 24 is increased. The driving force of 34) increases or decreases according to the running state of the vehicle. Therefore,
The power assist characteristics can be changed depending on the low speed running state and the high speed state of the vehicle when the vehicle is stationary, etc., and power assist based on the running state of the vehicle is performed like the conventional hydraulic power steering device. Steering rod 24 with a predetermined output torque
Can be output to

As described above, in the power steering apparatus 10 according to the present embodiment, the moving mechanism section 50 is changed according to the running state of the vehicle.
The (output torque control means) operates to change the contact state of the brush 76 and the brush 78 with respect to the armature 36, thereby controlling the drive of the motor unit 34 according to the running state of the vehicle. The assistance can be done well. Further, the structure is simple, and the cost and the size and weight can be significantly reduced. In addition, since it has a simple structure that does not require a torque sensor, a motor controller, and the like as in the related art, it is possible to significantly reduce costs and reduce size and weight.

Further, in the power steering apparatus 10, the input shaft 1
Independently of 2, the motor portion 34 is directly connected to the steered rod 24 as a rack member, the swing of the input shaft 12 is transmitted by the lever 202, and the second pole piece 40 is rotated around the axis. . In this way, the motor unit 34 is connected to the input shaft 12
Since it can be separated and placed independently, the mountability on the vehicle is improved. Therefore, it is possible to easily increase the size of the motor unit 34 and increase the output. Further, since the limit switch 214 that switches the energization direction to the motor unit 34 (armature 36) is integrally provided in the motor unit 34, the limit switch 214 is operated by the movement of the lever 202, which is a simple configuration. The device structure can be simplified.

In this embodiment, the moving mechanism 50 is operated in accordance with the running state (vehicle speed) of the vehicle to change the contact state of the brush 76 and the brush 78 with the armature 36. The configuration is not limited to this, and the moving mechanism unit 50 may be configured to operate according to the steering angle (rack stroke of the steered rod 24).

That is, for example, when the vehicle is in a straight traveling state (neutral state), the brush 76 and the brush 78 are set substantially orthogonal to the coil wire of the armature 36 as shown in FIG. Figure 8
As shown in (A), the brush 76 and the brush 78 may be changed so as to contact the coil wire of the armature 36 in a substantially parallel state. According to this, since the driving force of the motor unit 34 becomes small when the vehicle is traveling straight,
The power assist force applied to the steered rod 24 is also small, and the feeling of response is increased. On the other hand, since the driving force of the motor unit 34 increases with the steering, the power assist force applied to the steered rod 24 also increases, and the steering force of the input shaft 12 (steering wheel) is reduced.

Further, in the present embodiment, the actuator 6 for moving the operating lever 60 of the moving mechanism section 50.
Although 2 is a hydraulic cylinder, the invention is not limited to this, and the operating lever 60 may be moved by another moving source such as a solenoid coil. Furthermore, in the present embodiment, the brush 76 and the brush 78 are used.
The holder 52 for holding the actuator is connected to the operating lever 60 via the belt 58. However, the present invention is not limited to this.
The linear movement of the above may be converted into the rotational movement of the holder 52.

[0041]

As described above, the power steering apparatus according to the present invention has an excellent effect that a predetermined output torque corresponding to the running state of the vehicle can be output to the steering output shaft to perform optimum power assist. have.

[Brief description of drawings]

FIG. 1 is a cross-sectional view, as viewed from the front, showing the entire configuration of a power steering device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the entire configuration of the power steering device according to the embodiment of the present invention, as viewed from the rear side.

FIG. 3 is a sectional view taken along line 3-3 in FIG. 2 showing a configuration of a motor unit of the power steering apparatus according to the embodiment of the present invention.

FIG. 4 is a schematic configuration diagram showing an operating state of a limit switch of the power steering apparatus according to the embodiment of the present invention.

FIG. 5 is a partially cutaway schematic front view showing the configuration of the moving mechanism section of the power steering apparatus according to the embodiment of the present invention.

FIG. 6 is a partially cutaway schematic plan view showing a configuration of a moving mechanism portion of the power steering apparatus according to the embodiment of the present invention.

FIG. 7 is a schematic cross-sectional view corresponding to FIG. 6 showing a configuration of a moving mechanism portion of the power steering apparatus according to the embodiment of the present invention.

FIG. 8 is a schematic configuration diagram showing a correspondence relationship between a brush and a coil wire of an armature of the power steering apparatus according to the embodiment of the present invention.

[Explanation of Codes] 10 Power Steering Device 12 Input Shaft (Steering Input Shaft) 24 Steering Rod (Steering Output Shaft) 34 Motor Section 36 Armature 38 First Magnetic Pole 40 Second Magnetic Pole 42 Motor Rotation Shaft 50 Moving mechanism (output torque control means) 52 Holder 58 Belt 60 Actuating lever 62 Actuator 76 Brush (power feeding brush) 78 Brush (power feeding brush) 176 Holding plate 202 Lever (connecting member) 214 Limit switch (energization switching mechanism)

Claims (3)

[Claims] 1. A motor based on an input torque from a steering input shaft connected to a steering wheel by a motor including an armature and first and second magnetic poles provided on opposite sides of the armature. In a power steering apparatus that performs power assist to output a predetermined output torque to a steering output shaft for steering steered wheels, in a power supply brush of the motor according to a left-right rotation direction of the steering input shaft. An energization switching mechanism that switches the energization direction, and an output torque control unit that changes the contact state of the power feeding brush with the armature according to the running state of the vehicle and controls the power assist force of the motor. Characteristic power steering device. 2. The power assist of the motor is configured such that the facing positions of the first magnetic pole piece and the second magnetic pole piece are relatively changed around the axis according to the magnitude of the input torque from the steering input shaft. The power steering apparatus according to claim 1, further comprising magnetic pole control means for controlling force. 3. The magnetic pole control means includes the first and second magnetic pole control means.
Any one of the magnetic pole pieces of the steering wheel and the steering input shaft are coupled to each other to transmit the swing caused by the left and right rotation of the steering input shaft to transmit the first input.
And a connecting member for moving one of the second magnetic pole pieces around the axis, and the energization switching mechanism is integrally provided on the motor and is connected to the connecting member and is operated by the connecting member. The power steering apparatus according to claim 2.