JPH01249575A - Electrically driven power steering device - Google Patents

Abstract

PURPOSE:To enhance reliability, when a control means performs misoperation, by constituting a device forming a clutch, transmitting rotation of an electric motor to an output shaft side, to be provided with two or more paired rolls and controlling interrupted action of the clutch by rotating the electric motor and by elastically deforming a torsion bar. CONSTITUTION:An input shaft 11, to which steering force of a steering wheel is transmitted, is connected to an output shaft 12, connected to a steering gear, by a torsion bar 13 so as to enable the steering force to be transmitted, and one end of the output shaft 12 is fitted with a play into a large contour part 11b of the input shaft 11. While a device is constituted controlling an electric motor being based on an output from a steering torque detector S detecting steering torque in accordance with the elastic deformation of the torsion bar 13 and transmitting power of the electric motor from a worm gear 25 to the output shaft 12 through a clutch containing an outer sleeve 23. And the clutch is constituted forming three holes 11d in an angular part 11, formed in the large contour part 11b of the input shaft 11 and fitted to a hexagonal part 11c of the output shaft 12, and fitting a pair of rolls 22 respectively to the holes 11d.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to an electric power steering for a vehicle that uses an electric motor as a power source in order to reduce the steering force of the steering wheel of the vehicle. More specifically, the present invention relates to an electric power steering device equipped with a clutch device for ensuring fail-safety in the event of an abnormality such as a failure of the electric motor.

(Prior Art) As the above-mentioned conventional device, for example, Japanese Patent Laid-Open No. 61-37
There was one shown in Publication No. 581.

This device drives an electric motor using a control circuit in response to a signal from a torque detector that detects steering torque generated between an input shaft and an output shaft, or a signal from a vehicle speed detector, and transfers the driving force of the electric motor to a clutch. The power is transmitted to the output shaft via the speed reducer and reduces the steering force of the steering wheel connected to the input shaft.

This device uses an electromagnetic clutch controlled by the same control circuit as an example of a clutch interposed between the electric motor and the speed reducer. The -OFF control not only improves the steering feeling, but also enables manual steering by turning OFF when an abnormality occurs, ensuring fail-safety. In addition, as an example of another clutch adopted by this device, a ball is interposed between the electric motor and the speed reducer in the fitting gap between the cylindrical shaft and the hexagonal cross-section shaft, and the driving force from the electric motor is transmitted to the output shaft. However, on the other hand, there is a mechanical clutch that does not transmit the driving force from the output shaft to the electric motor. By employing this mechanical clutch, even if the electric motor becomes abnormal, for example in a locked state, there is no problem with manual steering, ensuring fail-safety.

(Problems to be Solved by the Invention) However, in the conventional device described above, among the clutches interposed between the electric motor and the reduction gear, in the case of an electromagnetic clutch that is controlled from ON to OFF by a control circuit, Due to factors other than the clutch itself, such as malfunction of the control circuit, the electromagnetic clutch may become inoperable and the steering feeling may deteriorate significantly. In other words, for example, when the electric motor malfunctions and becomes unable to rotate, the electromagnetic clutch may not be turned off due to factors other than the electromagnetic clutch itself as described above, and steering becomes impossible. Even if the electric motor is rotated in a direction opposite to the direction of rotation input to the input shaft, the clutch may not be turned off and steering may become impossible. In addition, with this device, when the electric motor becomes unable to rotate due to foreign matter getting caught, etc., it is not possible to immediately detect the abnormality, so the electromagnetic clutch is not turned off and steering becomes impossible. , it is not immediately possible to determine whether this means the end of steering or an abnormality in the electric motor, which may make the vehicle run unstable.

On the other hand, in the case of mechanical clutches mentioned on the other side, for example, when an abnormality occurs in the control circuit and the electric motor rotates in the opposite direction to the steering direction, a load is applied to the electric motor and steering becomes impossible. In this case, similar to the electromagnetic clutch described above, since the abnormality cannot be detected immediately, the running of the vehicle may become unstable.

Furthermore, since this mechanical clutch has a structure in which a freely rotating ball is simply interposed, the connection between the electric motor and the reducer is unstable, and especially when sudden steering is performed under high load, the electric motor also becomes unstable. As the ball starts rotating at high speed, it moves at one end at high speed into a narrow tapered space between the hexagonal shaft and the cylindrical shaft, and the impact may cause it to bounce back and return to the wider space, causing the clutch to instantly disengage and assist. As a result of the loss of power, a problem arises in that the steering force suddenly becomes heavy.

This is because the clutch in the conventional device described above connects and disconnects the electric motor and the output shaft using an electric signal, or unilaterally transmits the driving force from the electric motor to the output shaft. This is because interlocking is not performed mechanically.

As described above, the conventional devices have a problem in that the safety and reliability of the electric power steering device are not sufficiently ensured.

Therefore, in view of the above-mentioned conventional problems, the present invention improves the safety and reliability of an electric power steering device when an abnormality occurs in the electric motor, and improves the steering feeling of the electric power steering device and the reliability of the clutch. The technical challenge is to improve it.

Structure of the Invention C] (Means for Solving the Problem) The means taken to solve the above-mentioned technical problem is to connect an input shaft connected to a steering wheel of a vehicle and an output shaft connected to a steering gear. a steering torque detector that detects a steering torque applied therebetween; an electric motor whose rotation is controlled by a control signal from a control means in response to a detection signal from the steering torque detector, and whose rotation is transmitted to an output shaft; In the electric power steering device, the steering torque detector includes a clutch that is interposed between the electric motor and the output shaft and controls transmission of the rotation of the electric motor to the output shaft on and off. a cylindrical outer ring that detects steering torque in accordance with elastic deformation of an elastic body connecting the clutch and that is arranged to decelerate the rotation of the electric motor by disposing the clutch concentrically with the output shaft and leaving a gap between the two; , a plurality of pieces disposed within the gap and capable of engaging between the inner circumferential surface of the cylindrical outer ring and the outer circumferential surface of the output shaft in accordance with rotation of the human power shaft to connect the cylindrical outer ring and the output shaft; The engagement member is arranged in the gap so as to bias the retaining member toward the engagement side, and is compressed in response to the rotation of the input shaft, and the engagement member is compressed in response to the magnitude of the steering torque. and an elastic member that increases the resultant force, and the clutch is configured to control connection and disconnection of the output shaft and the electric motor by elastic deformation of the elastic body, and when the elastic member of the clutch is fully compressed, The elastic deformation of the elastic body is made larger than the elastic deformation of the elastic body when the input shaft and the output shaft are mechanically connected.

(Function) According to the above configuration, even if the electric motor is rotated in the opposite direction to the rotation according to the steering torque detected by the steering torque detector due to a malfunction of the control means, etc., the clutch is made of an elastic body. Its on/off is controlled by the elastic deformation of the elastic body, and only when the direction of rotation of the electric motor and the direction of elastic deformation of the elastic body match, the elastic body engages to transmit the rotation of the electric motor to the output shaft from the electric motor to the output shaft. Transmits the force of
When the two do not match, the clutch is always disengaged and no force is transmitted between the electric motor and the output shaft, so manual steering is possible and the steering operation is not disabled.

In addition, according to the configuration described in ``2'', the engagement force between the cylindrical outer ring of the engagement member and the output shaft is increased by the elastic member according to the magnitude of the steering torque, so that, for example, sudden steering is performed under high load. Even in such a case, the engaging member reliably engages the cylindrical outer ring and the output shaft to ensure support from the electric motor, and the elastic member is compressed in accordance with the rotation of the input shaft before being completely compressed. Since the input shaft and the output shaft are mechanically connected, force transmission between the input shaft and the output shaft is prevented through the fully compressed elastic member, thereby preventing damage to the elastic member. This improves the reliability of the clutch.

(Example) Hereinafter, an example of an electric power steering device according to the present invention will be described based on the drawings.

In FIGS. 1 and 2, the input shaft 11, which has one end connected to the steering wheel 10, has a hollow stepped tube shape, and the other end is one end of the torsion bar 13, which is connected to the output shaft 12 by a pin 15b. are connected to each other by a pin 15a. As a result, the input shaft 11 is connected to an output shaft 12 connected to a steering gear (not shown) of the vehicle via the torsion bar 13, and one end of the output shaft 12 is allowed to play freely within the large diameter portion 11b of the input shaft 11. The steering force applied to the input shaft 11 is transmitted to the output shaft 12 via the torsion bar 13. Note that the torsion bar 13 constitutes an elastic body in the present invention.

The input shaft 11 is rotatably supported on the steering wheel 10 side by a bearing 16 press-fitted into the upper housing 14a, and the output shaft 12 is rotatably supported by a bearing 17 press-fitted into the lower housing 14b. has been done.

A dust cover 36 is fitted on the outer periphery of the small diameter portion 11a of the input shaft 11 on the outside of the upper housing 14a, and a finger-like portion of a cylindrical slider 18 as shown in FIG. 4 is fitted inside the upper housing 14a. 18b is loosely fitted, and the slider 18 has a radial hole 18a on the output shaft 12 side into which a ball 19 that is engaged with a spiral groove 12a formed on the outer peripheral surface of the output shaft 12 is fitted. is provided. Three finger-shaped parts 18b are formed at equal intervals,
Each finger-shaped portion 18b is loosely fitted into a through hole lie formed in a stepped portion of the input shaft II.

A ring 20 having flanges at both ends and forming an annular groove 20a between the flanges is fixed to the outer periphery of the finger portion 18b of the slider 18 so as to be integral with the slider 18. Further, an elongated hole 18C in the axial direction into which a pin 21 fixed to the human power shaft 11 is inserted is formed on the outer periphery of one of the finger-shaped portions 18b of the slider 18, so that the slider 18 is connected to the input shaft 11. It is integrally rotatable and can freely move in the axial direction.

The outer circumferential surface of the output shaft 12 is provided with the aforementioned spiral groove 12a.
is engraved, and a hexagonal hexagonal portion 12b is formed. The large diameter portion 11b of the input shaft 11 is the output shaft 12
It extends to the hexagonal part 12b of the large diameter part 11b, and the fitting surface with the hexagonal part 12b of the large diameter part 11b has a hexagonal part corresponding to the hexagonal part 12b.
A corner portion 11c having a square shape is formed, and the corner portion 1
A predetermined gap is formed between 1c and the hexagonal portion 12b.

A corner portion 11c formed in the large diameter portion 11b of the input shaft 11 is provided with three holes lid at equally spaced positions. Each hole
Inside the ID, a pair of cylindrical rollers 22 have their axes aligned with the axial directions of the output shafts 11 and 12, as shown in enlarged views in FIGS. 3a and 3b, respectively. In this embodiment, a plate-shaped spring 33 made of a corrugated plate is interposed between each pair of rollers 22. As a result, each roller 22 is pressed against the circumferential end surface of the hole lid and is in contact with one end surface of the hexagonal portion 12b.
and the outer sleeve 23 constitute a clutch in the present invention.

Further, on the outside of the large diameter portion 11b of the input shaft 11, an outer sleeve 23 is press-fitted into the upper housing 14a so that a predetermined gap l is formed between the outer sleeve 23 and the output shaft 12. It is rotatably supported by a bearing 32 fixedly attached to the bearing 32 . A worm wheel 23a that meshes with a worm 25 fixed to an output shaft 24a of an electric motor 24 is formed on the outer peripheral surface of the outer sleeve 23, and the worm 25 and the worm wheel 23a constitute a speed reducer of the present invention. are doing. In addition, in FIG. 2, 30 and 31 are bearings that support the large diameter portion 11b of the input shaft 11 and the outer sleeve 23, respectively.

Further, a case 26 is attached to the upper housing 14a, and a ball 27 is provided at one end of the case 26.
Lever 2 consisting of a leaf spring-like metal plate that holds
The other end of 8 is fixed.

The ball 27 held at one end of the lever 28 is connected to the ring 20
The lever 28 is fitted into an annular groove 20a, and a strain gauge (not shown) forming a resistance bridge is attached to the side surface of the lever 28, which is coated with an insulating layer. The strain gauge constitutes a well-known strain detection circuit consisting of a bridge circuit, and the electric signal from the strain gauge is manually input to the control circuit 29, which in turn controls the electric motor 24 according to the electric signal. Control the supply current.

The operation of this embodiment having the above configuration will be explained.

When the steering wheel 10 is rotated, the input shaft 11
The torsion bar 13 is twisted with respect to the output shaft 12 connected to the steering gear, which rotates and is subjected to a load such as a road reaction force, and a relative rotation occurs between the output shaft 12 and the input shaft 11.

As a result, the relative rotation of this input shaft 11, that is, the output shaft 1
2, the slider rotates 180 times with respect to the spiral groove 12°a, and this rotation applies thrust in the axial direction of the input shaft 11 to the slider 18 via the ball 19, causing the slider 18 to move toward the input shaft. 11 rotation direction and input shaft 1
displacement in the axial direction according to the relative rotation of 1. Slider 1
The axial displacement of 8 is determined by bending the lever 28 that holds the ball 27 through the ball 27 that engages with the annular groove 20a of the ring 20, and adjusting the strain gauge according to the amount of relative rotation between the input shaft 11 and the output shaft 12. Generate an electrical signal. This electric signal is input to the control circuit 29, and the control circuit 29 sends a supply current according to this electric signal to the electric motor 24, and the electric motor 24
is rotated in a direction corresponding to the rotational direction of the input shaft 11, and the rotation of the electric motor 24 is decelerated by the worm 25 and the worm wheel 23a and transmitted to the outer sleeve 23.

At this time, in the present invention, the clutch is engaged and engaged as follows. That is, FIG. 3a shows the state of the clutch when the steering torque detector S is in the neutral position, and each roller 22 has a gap l with respect to the outer sleeve 23,
Input shaft 11. Neither the output shaft 12 nor the output shaft 12 is coupled to the outer sleeve 23, that is, the electric motor 24. From this state,
When the input shaft 11 is rotated to the left in the direction of the arrow in FIG. 3A, the rollers 22 on the left side in the rotational direction are
The gap l between the outer sleeve 23 and the outer sleeve 23 disappears, and the left roller 22 is pressed between the inner surface of the outer sleeve 23 and the hexagonal part 12b of the output shaft 12, and the clutch is activated, and in this state, the electric motor 24 is The supply of current is started, and the outer sleeve 23 begins to rotate in the same direction as the input shaft 11. As a result, the rotation of the outer sleeve 23 is smoothly transmitted to the output shaft 12 via the rollers 22 with the rollers 22 on the rotational direction side pressed against the inner surface of the outer sleeve 23 and the end face of the hexagonal part 12b, and the steering wheel 10 assists the applied steering force. Here, the rotation direction of the outer sleeve 23 is controlled by the control circuit 29 to control the rotation of the electric motor 24 at a rotation speed and rotation direction according to the relative rotation of the input shaft 11 and the output shaft 12. The direction of the relative rotation of the human power shaft 11 coincides with the direction of elastic deformation of the shaft. Therefore, the rollers 22 on the side in the rotational direction are strongly pressed against the hexagonal portion 12b by the frictional force, and the rotational force is reliably transmitted.

At this time, the road reaction force is large (if the input shaft 11 is further rotated to the left in order to increase the current supplied to the electric motor 24, the rollers 22 on the rotation direction side will be at the position shown in Fig. 30). The roller 22 on the counter-rotation direction side deflects the spring 33 by the large diameter portion 11b and is displaced to the left-rotation direction side.Therefore, the road reaction force is large, and the amount of relative rotation between the person and the output shafts 11 and 12 becomes large. As the driving force of the electric motor 24 increases, in order to increase the engagement force of the clutch, the pressing force of the spring 33 on the rollers 22 on the rotation direction side is increased to ensure that the clutch is engaged. 11 large diameter part 11
If the roller 22 is simply inserted into the hole lid formed in the hole lid, or if no appropriate pressing force is applied to the pair of rollers 22, for example, even though the resistance on the ground contact side is large, a quick steering is performed and the input is When the relative rotation between the shaft 11 and the output shaft 12 increases, the electric motor 24 rotates at high speed, and the rollers 22 on the rotation direction side suddenly engage with the output shaft 12 and the outer sleeve 23. The reaction force may cause the clutch to dislodge and suddenly lose assist, resulting in a momentary increase in steering force.
3, as the amount of relative rotation increases, the pressing force of the rollers 22 on the rotational direction side increases, so even in the above case, engagement of the clutch is ensured and stable assistance is performed.

Further, in the present invention, input torque Tm (steering torque applied to steering wheel 10 - amount of elastic deformation of torsion bar 13) and output torque Ts (output shaft 1
The relationship between the input torques Tm2 and Tm2° when the spring 33 is completely compressed (the corrugated plate is fully extended) is as shown in Figure 5.
The amount of elastic deformation of the torsion bar 13 - the input torque Tm) is made larger than the input torques Tml and Tml' when the input shaft 11 and the output shaft 12 are mechanically connected. This prevents torque from being transmitted between the input shaft 11 and the output shaft 12 via the fully compressed spring 33, thereby preventing damage to the spring 33 and improving the reliability of the clutch. In this embodiment, the mechanical connection between the human power shaft 11 and the output shaft 12 is
This is done by engaging the inner surface of the corner 11C formed in the large diameter portion 11b of the output shaft 12 with the outer surface of the hexagonal portion 12b of the output shaft 12, and Tml, Tm2 (Tml
', Tm2°) are the spring constant of the torsion bar 13, the inner diameter dimension of the outer sleeve 23, the outer diameter of the roller 22,
The middle dimension of the corner llC of the input shaft 11, 6 of the output shaft 12
It can be arbitrarily set by various combinations of the width across flats of the corner portion 12b, the hole 11d of the input shaft 11, the spring constant and dimensions of the spring 33, etc. In addition, the input shaft 11
The mechanical connection between the output shaft 12 and the output shaft 12 is TmL < Tm2 (
As long as the relationship (Tml'<Tm2') is maintained, it may be used anywhere, and a compression coil spring may be used as the spring 33.

In this way, the clutch in this embodiment has the input shaft 11
and the relative rotation (input torque Tm) of the output shaft 12 is greater than a certain set value, and the direction of the relative rotation and the outer sleeve 2
The rotation of the outer sleeve 23 is transmitted to the output shaft 12 only when the directions of rotation of the outer sleeve 23 and the outer sleeve 23 coincide with each other. Therefore,
Even if the electric motor 24 is rotated in the opposite direction to the rotation direction according to the relative rotation between the input shaft 11 and the output shaft 12 due to a malfunction of the control circuit 29, etc., the rollers on the left side (rotation direction side) in FIG. 22 is in contact with the inner circumferential surface of the outer sleeve 23 and the end surface of the hexagonal portion 12b of the output shaft 12, and vibrates and rotates within the hole lld due to the frictional force with the outer sleeve 23. Output shaft 11
．． On the other hand, the rotation of the input shaft 11 is transmitted to the output shaft 12 through a mechanical connection or torsion bar 13 by the engagement of the corner portion 11c and the hexagonal portion 12b, and is transmitted to the output shaft 12 through manual steering. enable.

In addition, when the electric motor 24 suddenly rotates at a high speed in the same direction as the relative rotation between the input shaft If and the output shaft 12 due to a malfunction of the control circuit 29, the input shaft 11 side becomes a resistance and the 3rd C In the figure, the roller 22 on the left side in the figure is pushed in the right direction (in the opposite rotational direction) in the figure by the left end surface of the hole lid of the input shaft 11, and the roller 22 on the left side in the figure separates from the inner surface of the outer sleeve 23, causing the clutch to become inoperative. state, the rotation of the input shaft 11 is transmitted to the output shaft 12 via the torsion bar 13, making manual steering possible.

Furthermore, even if the electric motor 24 catches a foreign object and becomes unable to rotate, and thereby the outer sleeve 23 becomes unable to rotate, the roller 22 on the left side in FIG.
The input shaft 1 may vibrate against the
1 rotation is transmitted to the output shaft 12 via the torsion bar 13, and manual steering is performed. Therefore, input shaft 1
1 is assisted by the electric motor 24 in one direction, and even when the electric motor 24 becomes unable to rotate and the input shaft 11 is further rotated in the direction in which it was assisted, the roller 22 on the left side in FIG. 3C vibrates. Or rotate, input shaft 1
1 rotation is transmitted to the output shaft 12 via the torsion bar 13. Furthermore, even if the input shaft 11 is assisted in one direction by the electric motor 24 and the electric motor 24 becomes unable to rotate and it becomes necessary to return the input shaft 11 in the opposite direction, the rollers on the left side in FIG. 22 is pushed in the right direction (returning direction) in the figure by the left end surface of the hole 11 (i in the figure) of the input shaft 11, and the roller 22 on the left side in the figure pushes against the outer sleeve 2.
3, the clutch becomes inactive and the output shaft 11.12 becomes rotatable relative to the outer sleeve 23, allowing manual steering. Furthermore, even if the electric motor 24 rotates due to a malfunction of the control circuit 29 while the vehicle is traveling straight, the clutch is activated by the relative rotation between the input shaft 11 and the output shaft 12 (the elasticity of the torsion bar 13) due to the road reaction force. Since no torque is transmitted between the outer sleeve 23 and the output shaft 12 unless the deformation (input torque Tm) exceeds a set value, the steering wheel 10 is not suddenly cut. Furthermore, even when sudden steering is performed despite a large road load, for example, the larger the amount of relative rotation between the input shaft 11 and the output shaft 12, the more the inner surface of the outer sleeve 23 of the roller 22 and the hexagonal shape of the output shaft 12. The pressing force against the end face of the portion 12b increases, and the sudden rotation start of the outer sleeve 23 is closely followed to ensure engagement with the output shaft 12.

As described above, according to the present embodiment, the clutch operates to intermittent rotation transmission between the electric motor 24 and the reduction gear by utilizing the elastic deformation of the torsion bar 13 for detecting the relative rotation of the human power shaft 11. By controlling the electric power steering, the safety and reliability of the electric power steering can be improved, and the device can be downsized. Moreover, the steering feeling of the electric power steering device and the reliability of the clutch can be improved.

FIG. 6 shows a modification of the electric power steering device according to the present invention. In this embodiment, relative rotation occurring between the input shaft and the output shaft in the embodiment shown in FIG. The only difference is that the relative rotation is directly detected, whereas the axial direction conversion mechanism is provided, and the other configurations and operations are the same as the embodiment shown in FIG. 2, so the details will be explained here. Further explanation will be omitted.

In FIG. 6, a flange portion 111e is formed at the end of the large diameter portion 111b of the input shaft 111, and the output shaft 11
A flange portion 112c is formed on the outer peripheral surface of 2. Brush 1 is installed between the end faces of both flanges ttte and +12C.
A slip ring is configured with 34 in between, so that an electric signal corresponding to the relative rotation between the two is detected. In this embodiment, the configuration for detecting relative rotation is simple, and since the number of parts is small, there is little backlash between each member, and highly accurate detection is possible. In addition,
In FIG. 6, the same configuration as the embodiment shown in FIG.
The number code attached to the figure is 1o.

A number code is added.

In the above two embodiments, examples have been explained in which a cantilever type using a strain gauge and a slip ring type were used as detectors for extracting the relative rotation of the input shaft as an electric signal. It is also possible to employ a detector or the like in the present invention.

〔Effect of the invention〕

According to the present invention, the steering torque detector detects the steering torque in accordance with the elastic deformation of the elastic body that connects the input shaft and the output shaft, and the engagement and disengagement of the clutch is determined based on the steering torque detected by the steering torque detector. It is controlled by the rotation of the electric motor and the elastic deformation of the elastic body.

Therefore, even if the electric motor is rotated in the opposite direction to the rotation according to the steering torque detected by the steering torque detector due to a malfunction of the control means, the clutch will rotate according to the steering torque detected by the steering torque detector. The connection is controlled by the corresponding rotation and the elastic deformation of the elastic body, and the rotation of the electric motor is transmitted to the output shaft only when the direction of rotation of the reducer by the electric motor and the direction of elastic deformation of the elastic body match. When the two do not match, the clutch is always disengaged and no force is transmitted between the electric motor and the output shaft, so manual steering is possible and the steering operation is not disabled.

Therefore, the safety and reliability of the electric power steering device can be improved.

Furthermore, since the steering torque detector and the clutch in the present invention share an elastic body that requires a large space,
Electric power steering can be made more compact.

Furthermore, according to the present invention, an elastic member that increases the engagement force of the clutch retaining member in accordance with the steering torque is disposed in the gap between the cylindrical outer ring and the output shaft, and the elastic member increases as the input shaft rotates. The elastic deformation of the elastic body when fully compressed is made larger than the elastic deformation of the elastic body when the input shaft and the output shaft are mechanically connected.

Therefore, when the electric motor is operating normally, engagement of the clutch can be ensured, and torque from the input shaft is prevented from being transmitted to the output shaft via the fully compressed elastic member. As a result, damage to the elastic member can be prevented and reliability of the clutch can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a schematic configuration of an embodiment of an electric power steering device according to the present invention, and FIG.
Longitudinal cross-sectional view showing details of the embodiment shown in the figure, Figure 3a, Figure 3.
Figure b and Figure 3C are explanatory diagrams of the clutch in the embodiment shown in Figure 2, Figure 4 is a diagram showing the slider in Figure 1, and Figure 5 is an illustration of the input torque Tm in the embodiment shown in Figure 2.
(Steering torque - elastic deformation of elastic body) and output torque Ts
FIG. 6 is a longitudinal sectional view showing a modified embodiment of the present invention. 10... Steering wheel, 11,111...
Input shaft, llc, 1llc... corner, lid, 1ll
d...-hole, 11113--flange part, 12, 11
2... Output shaft, 12a... Groove, 12b, 112b.
... Hexagonal part, 112C... Flange part, 13,113
...Torsion bar, 18...Slider, 19...
- Ball, 20... Ring, 22, 122... Roller, 23.123... Outer sleeve, 23a. 123a... Gear, 24, 124... Electric motor,
25.125... Worm gear, 27... Ball,
28...Lever, 29...Control circuit, 33...Spring, 134...Brush. ;3a; ko3c'':.

Claims (1)

[Claims] A steering torque detector that detects a steering torque applied between an input shaft connected to a steering wheel of a vehicle and an output shaft connected to a steering gear, and a control means responsive to a detection signal from the steering torque detector. an electric motor whose rotation is controlled by a control signal and whose rotation is transmitted to the output shaft; and an electric motor which is interposed between the electric motor and the output shaft and controls intermittently the transmission of the rotation of the electric motor to the output shaft. In the electric power steering device, the steering torque detector detects steering torque according to elastic deformation of an elastic body connecting the input shaft and the output shaft, and the clutch is connected to the output shaft. a cylindrical outer ring that is arranged concentrically with a gap left between them and decelerates the rotation of the electric motor; a plurality of engaging members that can engage between the outer peripheral surfaces of the output shaft and connect the cylindrical outer ring and the output shaft; and a plurality of engaging members disposed within the gap so as to bias the engaging members toward the engaging side. an elastic member that is compressed in accordance with the rotation of the input shaft and increases the engagement force of the engagement member in accordance with the magnitude of the steering torque, and the clutch is connected to the output shaft by elastic deformation of the elastic body. The on/off of the electric motor is controlled, and the elastic deformation of the elastic body when the elastic member of the clutch is fully compressed is the same as the elastic deformation when the input shaft and the output shaft are mechanically connected. An electric power steering device characterized in that the elastic deformation is larger than that of an elastic body.