JPH1120716A - Power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simply constructed inexpensive power steering device, by which predetermined output torque complying with steering torque of a steering wheel can be outputted to a steering output shaft and optimum power assist can be accomplished. SOLUTION: In a power steering device 10, the second magnetic pole element 40, which can be rotated relatively to the first magnetic pole element, in a motor unit 34 is rotated by means of a small motor 60. The small motor 60 is driven on the basis of input torque detection signals from oscillation sensors 52A, 52B. The small motor 60 is driven in compliance with the steering torque when a steering wheel is steered, and the second magnetic pole element 40 is rotated relatively to the first magnetic pole element, so that magnetic flux density fluctuates, and as a result, a motor driving force complying with the steering force is applied to a steering rod 24. By means of a limit switch 214, the excitation direction to the motor unit 34 is switched in compliance with the steering direction for application to rightward or leftward steering.

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 A power steering device (so-called,
Among power steering devices), those having a configuration in which a steering assist force (assist force) is generated by a motor are generally known (for example, Japanese Patent Application Laid-Open No. Hei 6-171518).

[0003] This power steering device (electric power steering device) includes a motor for generating a steering assist force in addition to a steering mechanism including a steering shaft and the like. This motor is connected to the steering shaft and has a configuration capable of transmitting a driving torque. Further, a torsion bar is interposed in the middle of the steering shaft, and a torque detecting mechanism (torque sensor) is provided on the torsion bar. When the steering wheel is steered, the steering torque is detected by a torque detection mechanism, the motor is driven based on the detected steering torque, and the driving torque of the motor is transmitted to the steering shaft to obtain a steering assist force. It has become. In such an electric power steering device, the motor is driven in accordance with the steering torque of the steering wheel, and the steering force can be favorably assisted.

However, in the conventional electric power steering apparatus disclosed in the above publication, components such as a torque sensor or a large motor controller for supplying a large current are used to control the motor in accordance with the steering torque of the steering wheel. This is an indispensable configuration, and has the drawback that the system as a whole is large, complicated, and expensive.

[0005]

SUMMARY OF THE INVENTION In consideration of the above facts, the present invention outputs a predetermined output torque corresponding to the steering torque from a steering input shaft to a steering output shaft at a low cost by using a simple structure and low cost. An object is to obtain a power steering device capable of performing power assist.

[0006]

According to a first aspect of the present invention, there is provided a power steering apparatus comprising a motor having an armature and first and second magnetic poles provided on both sides of the armature. A power steering device that performs a power assist based on an input torque from a steering input shaft connected to a steering means and outputs a predetermined output torque to a steering output shaft for steering a steered wheel; An energization switching mechanism for switching the energization direction to the power supply brush of the motor according to the left and right rotation directions of the input shaft, and detecting a swing caused by the left and right rotation according to the magnitude of the input torque of the steering input shaft; An input torque detecting unit, which is connected to one of the first and second magnetic poles, and an opposing position between the first magnetic pole and the second magnetic pole based on a detection result by the input torque detecting unit; Relative to the axis Change is characterized by comprising a Jikyokuko driving means for controlling the power assist force of the motor.

In the power steering apparatus according to the first aspect, a motor is connected to the steering output shaft connected to the 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 force of the steering input shaft (steering means) 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 swing caused by the left and right rotation corresponding to the magnitude of the input torque of the steering input shaft is detected by the input torque detecting means,
Further, the magnetic pole driving means is operated based on the detection result detected by the input torque detecting means. Thereby, the facing position of the first magnetic pole and the second magnetic pole is relatively changed around the axis. In this case, the operation of the magnetic pole driving means corresponds to the magnitude of the input torque from the steering input shaft, and the facing position between the first magnetic pole and the second magnetic pole corresponds to the magnitude of the input torque. Will be changed. Therefore, the magnetic flux density (magnetic field strength) of the motor (the first and second magnetic poles and the armature) changes according to the input torque. Therefore, the power assist force (motor driving force) output to the steering output shaft increases and decreases in proportion to the magnitude of the input torque from the steering input shaft. A predetermined output torque can be output to the steering output shaft by performing power assist based on the input torque from the steering input shaft.

As described above, in the power steering apparatus according to the first aspect, a predetermined output torque corresponding to the steering torque (of the steering means) from the steering input shaft is output to the steering output shaft at a low cost with a simple structure. Output to perform optimal power assist.

According to a second aspect of the present invention, in the power steering apparatus according to the first aspect, the power supply switching mechanism is provided integrally with the motor and connected to the magnetic pole driving means. It is characterized by being actuated by child drive means.

In the power steering apparatus according to the second aspect, the power supply switching mechanism provided integrally with the motor is operated by the magnetic pole driving means. That is, the change of the opposing positions of the first and second magnetic poles and the operation of the current supply switching mechanism are performed by the magnetic pole driving means. Therefore, the structure of the device can be simplified.

[0012]

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 device 10 is used, for example, as an electric power steering device for a vehicle, and includes an input shaft (steering shaft) 12. The input shaft 12 has one end arranged in a direction substantially orthogonal to the rack bar 24 as a steering output shaft, supported by the housing 194 by a bearing 192, and the other end provided with a steering wheel (steering means) (not shown). 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. Input shaft 1
2 is provided with a pinion 196, which meshes with a rack gear 198 of a rack bar 24 as a steering output shaft. In addition, a holding cylinder 200 that can move to the left and right corresponding to the input shaft 12 is provided at the tip of the input shaft 12.

As shown in FIG. 4, a magnet 50 is attached to the tip of the input shaft 12.
Opposite to the magnet 50, swing sensors 52A and 52B as input torque detecting means are arranged. The swing sensors 52A and 52B are, for example, Hall element sensors. When the input shaft 12 is steered to the right, for example, the magnet 50 moves toward the swing sensor 52A as shown in FIG. For example, at the time of left steering, the magnet 50 moves to the side of the swing sensor 52B as shown in FIG. 4B, and the swing sensors 52A and 52B generate electromotive force by the left and right movement of the magnet 50. That is, as shown by the line A in FIG.
The swing sensor 52B generates an electromotive force by the lateral movement of the magnet 50 as shown by a line B in FIG. Accordingly, the swing sensors 52A and 52B detect the left and right movement of the magnet 50, that is, the left and right swing about the bearing 192 of the input shaft 12 (in other words, the left and right switching state of the input shaft 12). It is a configuration that can be performed.

The swing sensors 52A and 52B are connected to a small motor 60 described later via a simple controller (not shown).

Further, the power steering device 10 includes a motor 3
4 is provided. The motor unit 34 is a so-called print motor, and includes an armature 36 and first and second magnetic poles 38 and 40 provided on both 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
A gear 204 is provided on the motor rotation shaft 42 of
Further, it is connected to a rack gear 210 of the rack bar 24 via a reduction gear 206 and a pinion 208.

On the other hand, the first magnetic pole 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
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.

The motor section 34 is provided integrally with a small motor 60 as a magnetic pole driving means. A worm gear 64 is attached to the rotation shaft 62 of the small motor 60, and the worm gear 64 is meshed with the gear 212 described above. Therefore, when the small motor 60 is driven, the gear 212, that is, the second
Is rotated and moved.

A limit switch 214 as an energization switching mechanism is provided integrally with the motor section 34. The limit switch 214 has an operating contact 216. The operating contact 216 is held by the lever 215 and moves together with the lever 215. further,
A gear portion 218 is formed at the upper end of the lever 215 and meshes with the gear 212 described above. For this reason,
When the gear 212 is rotated, the lever 215, that is, the operating contact 216 is moved left and right, respectively. The operating contact 216 is connected to the brush 7 of the motor unit 34.
6. Connected to the brush 78. In the limit switch 214, the fixed contact 2 is opposed to the operating contact 216.
17, 219 are provided. These fixed contacts 21
7, 219 are connected to a power supply. Thereby, the driving contact 216 moves left and right by driving the small motor 60 and contacts the fixed contacts 217 and 219, so that the direction of energization to the motor unit 34 (armature 36) can be switched.

Next, the operation of the present embodiment will be described. In the power steering device 10 having the above configuration, when the steering wheel (the input shaft 12) is not steered (the vehicle is in a straight running state), the swing sensors 52A and 52B do not detect the rotation (swing) of the input shaft 12. Therefore, the small motor 60 is not driven, the operating contact 216 of the limit switch 214 is not moved, and the limit switch 214 is kept in the OFF state, so that the motor unit 34 is not energized.

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

That is, when the input shaft 12 is steered in either the left or right direction, for example, when turning right as shown by the arrow A direction in FIG. 1, the steering force of the input shaft 12 is transmitted via the pinion 196 and the rack gear 198. The power is transmitted to the rack bar 24, and the rack bar 24 is driven in the axial direction (the direction of arrow D) to steer the steered wheels.

In this case, immediately after the input shaft 12 is steered, the rack bar 24 (that is, the tire side) has a large resistance, so that the rack bar 24 does not move. Therefore, the input shaft 12 is slightly moved around the bearing 192 as a fulcrum. Rocks. Therefore, the swing of the input shaft 12 is detected by the swing sensors 52A and 52B, the small motor 60 is driven, and the second magnetic pole piece 40 is rotated. Thereby, the first magnetic pole 3
8 and the second magnetic pole 40 are opposed relative to each other about the axis, and the polarity of each magnetic pole is changed from the same polarity state (N pole-N pole state or S pole-S pole state) to a different polarity. The state (N pole-S pole state or S pole-N pole state) is gradually changed.

Further, at this time, the operating contact 216 of the limit switch 214 moves with the driving of the small motor 60, the limit switch 214 is turned on, and the motor unit 34
(Armature 36), and the armature 36
Rotates.

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

On the other hand, when the input shaft 12 is steered to the left (in the direction of arrow C in FIG. 1), the steering force of the input shaft 12 becomes
The rack bar 24 is transmitted to the rack bar 24 via the rack gear 96 and the rack gear 198, and the rack bar 24 is driven in the axial direction (the direction of arrow B) to steer the steered wheels.

Also in this case, immediately after the input shaft 12 is steered, the rack bar 24 (ie, the tire side) has a large resistance, so that the rack bar 24 does not move. Therefore, the input shaft 12 is supported by the bearing 192 as a fulcrum. Swings slightly. Therefore, the swing of the input shaft 12 is controlled by the swing sensors 52A, 52B.
The small motor 60 is driven in the opposite direction to that described above, and the second magnetic pole element 40 is rotated. Thereby, the opposing positions of the first magnetic pole piece 38 and the second magnetic pole piece 40 are relatively changed around the axis, and the polarity of each magnetic pole piece is gradually changed from the same polarity state to the different polarity state. Further, at this time, the limit switch 2
14 moves in the opposite direction to the above, the limit switch 214 is turned on, and the motor unit 34 (the armature 3
6), the armature 36 of the motor section 34 rotates in the opposite direction to that described above.

Thus, the driving force of the motor section 34 acts on the rack bar 24 to which the motor rotating shaft 42 is connected, and is applied as an auxiliary driving force. Therefore, the input shaft 12
The steering force of the (steering wheel) is reduced.

In this case, the driving of the small motor 60 corresponds to the magnitude of the input torque from the input shaft 12, and
The opposing position between the magnetic pole 38 and the second magnetic pole 40 is changed according to the magnitude of the input torque. Accordingly, the driving force of the motor unit 34 increases and decreases in accordance with the input torque, and performs power assist based on the input torque from the input shaft 12 in the same manner as in a conventional power assist device (power steering device). A predetermined output torque can be applied to the rack bar 24.

The steering wheel (input shaft 1)
When the steering direction in 2) is switched between left and right, the energizing direction to the armature 36 of the motor section 34 is switched by the operation of the small motor 60 and the limit switch 214 as described above, and the rotation direction of the motor rotating shaft 42 is changed. Can be switched to correspond to the steering direction of the input shaft 12.

As described above, in the power steering apparatus 10 according to the present embodiment, the predetermined output torque corresponding to the steering torque of the steering wheel is output to the steering output shaft at a low cost with a simple structure and low cost. Power assist can be performed.

In the power steering device 10, the input shaft 12
Since the small motor 60 is driven based on the input torque from the motor to rotate the second magnetic pole 40 around the axis, the driving force of the motor unit 34 (ie, the auxiliary steering force)
Can be changed without affecting the steering force of the input shaft 12 even under the influence of the magnetic flux, so that the load on the driver does not increase and the steering feeling does not deteriorate.

Further, in the power steering device 10, the input shaft 1
The motor unit 34 is directly connected to the rack bar 24 as a rack member independently of the motor 2, and the swing of the input shaft 12 is detected by the swing sensors 52A and 52B, based on which the small motor 60 is driven. The second pole piece 40 is rotated around the axis. As described above, since the motor unit 34 can be disposed separately and independently from the input shaft 12, the mountability on the vehicle is improved. For this reason, it is possible to easily increase the size of the motor section 34 to increase the output. Further, a limit switch 214 for switching the direction of energization to the motor unit 34 (armature 36) is provided integrally with the motor unit 34, and the simple configuration is such that the limit switch 214 is operated by driving the small motor 60. Therefore, the structure of the device can be simplified.

In the above embodiment, the first magnetic pole 38 and the second magnetic pole 40 have a configuration in which an 8-pole magnetized portion is formed. However, the present invention is not limited to this. The number of poles may be used.

In the above embodiment, the magnetized portions of the first magnetic pole 38 and the second magnetic pole 40 are formed to have a magnetization angle of 45 degrees. The magnetization angle of the magnetized portion is not limited to this.

For example, as in the second magnetic pole piece 40 shown in FIG. 6, the configuration may be such that the magnetization angle of the magnetized portion is 35 degrees. In this case, the motor unit 3 according to the input torque
4 improves the responsiveness and can quickly generate the assist force. That is, the polarities of the first magnetic pole 38 and the second magnetic pole 40 are in the same polarity state (N pole-N pole state, or S pole state).
To change from the pole-S pole state to the different pole state (N pole-S pole state or S pole-N pole state) (in other words, to change the state of the assist force from the zero state to the maximum state). of)
The required movement rotation angle of the second magnetic pole piece 40 is reduced. Therefore, as a result, the first magnetic pole 38 and the second magnetic pole 4
0 can be quickly rotated relative to each other, so that the cyst force can be generated with even higher response, and the steering feeling can be improved.

[Brief description of the 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. 1 showing a configuration of a motor unit of the power steering apparatus according to the embodiment of the present invention.

FIG. 4 is a front view showing a correspondence relationship between an input shaft and a swing sensor of the power steering device according to the embodiment of the present invention.

FIG. 5 is a diagram showing a correspondence relationship between a steering direction detected by a swing sensor of the power steering apparatus according to the embodiment of the present invention and an output voltage.

FIG. 6 is a schematic plan view showing another example of the magnetized portion of the magnetic pole of the power steering apparatus according to the embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 10 power steering device 12 input shaft (steering input shaft) 24 rack bar (steering output shaft) 34 motor unit 36 armature 38 first magnetic pole 40 second magnetic pole 42 motor rotating shaft 50 magnet (input torque detecting means) 52A swing sensor (input torque detecting means) 52B swing sensor (input torque detecting means) 60 small motor (magnetic pole driving means) 214 limit switch (energization switching mechanism)

 ──────────────────────────────────────────────────続 き Continued from the front page (72) Inventor Shuji Fujita 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation

Claims (2)

[Claims] 1. A motor comprising an armature and first and second magnetic poles provided on opposite sides of the armature based on an input torque from a steering input shaft connected to steering means. In a power steering device that performs power assist and outputs a predetermined output torque to a steering output shaft for turning a steered wheel, a power supply brush of the motor is supplied to a power supply brush of the motor in accordance with a left-right rotation direction of the steering input shaft. An energization switching mechanism for switching an energization direction; input torque detection means for detecting a swing caused by left and right rotation according to the magnitude of the input torque of the steering input shaft; and any one of the first and second magnetic pole pieces And the first torque is connected based on the detection result by the input torque detecting means.
And a magnetic pole driving means for controlling the power assisting force of the motor by relatively changing the facing position between the magnetic pole and the second magnetic pole around the axis. . 2. The power steering apparatus according to claim 1, wherein the power supply switching mechanism is provided integrally with the motor and connected to the magnetic pole driving means to be operated by the magnetic pole driving means.