JPH0751973Y2 - Electric power steering device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial field of application) The present invention relates to an electric power steering for a vehicle that uses an electric motor as a power source to reduce the steering force of a steering wheel of the vehicle. More specifically, the present invention relates to an electric power steering device including a clutch device for ensuring a failsafe in an abnormal state such as a failure of an electric motor.

(Prior Art) As the above-mentioned conventional device, for example, JP-A-61-37581
There is the one shown in the official gazette.

In this device, a control circuit drives an electric motor in response to a signal from a torque detector that detects a steering torque generated between an input shaft and an output shaft or a signal from a vehicle speed detector, and a driving force of the electric motor is clutched. Also, the steering force of the steering wheel connected to the input shaft is reduced by transmitting the force to the output shaft via the speed reducer.

This device uses an electromagnetic clutch controlled by the control circuit as an example of the clutch interposed between the electric motor and the speed reducer.The electromagnetic clutch is controlled by the control circuit according to the vehicle speed. , ON-OFF control improves steering feeling, and OF
F steering allows manual steering and secures a fail safe. Further, as another example of the clutch adopted by this device, a ball is interposed between the electric motor and the reducer in the fitting gap between the cylindrical shaft and the hexagonal section shaft, and the driving force from the electric motor is transmitted to the output shaft. However, conversely, there is a mechanical clutch in which the driving force from the output shaft is not transmitted to the electric motor side. By adopting this mechanical clutch, even if the electric motor is in an abnormal state, for example, even if the electric motor is in a locked state, the manual steering is not hindered and the fail safe is secured.

(Problems to be solved by the invention) However, in the above-mentioned conventional device, among the clutches interposed between the electric motor and the speed reducer, in the case of the electromagnetic clutch that is ON-0FF controlled by the 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 be significantly deteriorated. That is, for example, when the electric motor becomes abnormal and becomes unrotatable, the electromagnetic clutch is not turned off due to factors other than the electromagnetic clutch itself as described above, and steering is impossible, and the above-mentioned factors. Therefore, even if the electric motor is rotated in the direction opposite to the rotation direction input to the input shaft, the clutch may not be turned off and steering may be disabled. Further, in this device, when the electric motor becomes unrotatable due to foreign matter being caught, the abnormality cannot be detected immediately, so the electromagnetic clutch is not turned off and steering becomes impossible. However, it may not be possible to immediately determine whether it means the end of steering or the abnormality of the electric motor, and the traveling of the vehicle may become unstable.

On the other hand, also in the case of the mechanical clutch mentioned as another example, when an abnormality occurs in the control circuit and the electric motor rotates in the direction opposite to the steering direction, a load is applied to the electric motor and steering becomes impossible. As with the electromagnetic clutch described above, the abnormality cannot be immediately detected at this time, which may make the running of the vehicle unstable. Furthermore, since this mechanical clutch has a structure in which a ball that freely rotates is simply interposed, the connection and disconnection between the electric motor and the speed reducer is unstable, and especially when a steep steering is performed under a high load, the electric motor also To start spinning at high speed,
The ball may once move at a high speed in a narrow tapered space sandwiched by a hexagonal axis and a cylindrical axis, and may be bounced back by the impact to return to a wide space. There is also a problem that the steering force becomes heavy and abnormal noise is generated.

This is because the clutch of the conventional device described above intermittently connects or disconnects the electric motor and the output shaft by an electric signal or unilaterally transmits the driving force from the electric motor to the output shaft. This is because they do not mechanically interlock with each other.

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

In view of the above-mentioned conventional problems, the present invention aims to improve the safety and reliability of the electric power steering device when the electric motor is abnormal, and to improve the certainty of the assisting action of the electric motor. This is a technical issue.

[Constitution of device]

(Means for Solving the Problems) Means taken for solving the above-mentioned technical problem is, in the electric power steering device, the input shaft is formed in a tubular shape, and the both shafts are provided through an elastic body. The steering torque detector is connected to detect steering torque according to elastic deformation of the elastic body, and a plurality of through holes are formed at an end portion of the input shaft and an outer peripheral surface of the output shaft is formed. The output shaft is loosely fitted to the end of the input shaft so that the multi-faced portion is formed and the through hole overlaps with each other, and the clutch is concentric with the input / output shaft and the input shaft. A cylindrical outer ring that is arranged with a gap left between and to which the rotation of the electric motor is transmitted, and an inner peripheral surface of the cylindrical outer ring that is arranged in the through hole and that corresponds to the rotation of the input shaft. And the cylindrical shape that engages with each of the multifaceted portions. An engaging member that can connect the outer ring and the output shaft, and a biasing unit that is disposed in the through hole and biases the engaging member to the one end surface of the through hole in the rotation direction side of the input shaft. The clutch controls the connection and disconnection of the output shaft and the electric motor by elastic deformation of the elastic body, and at the time of engagement of the engagement member of the clutch, rotation of the cylindrical outer ring causes the engagement member to move. A rotation restricting means for restricting rotation is provided, and the rotation restricting means is made of an elastic member fitted in an annular groove formed on the outer peripheral surface of the multifaceted portion of the output shaft, or the input of the through hole. An elastic member fixed to the end surface of the shaft in the rotation direction or the end portion of the biasing means on the engagement member side is used.

(Operation) According to the above-described configuration, even if the electric motor is rotated in a direction opposite to the rotation corresponding to the steering torque detected by the steering torque detector due to a malfunction of the control means or the like, for example, the clutch is made of an elastic material. Is controlled by the elastic deformation of the electric motor, and is engaged so as to transmit the rotation of the electric motor to the output shaft only when the rotation direction of the electric motor and the elastic deformation direction of the elastic body match. The torque is transmitted, and when the two do not match, the clutch is disengaged and the force is not transmitted between the electric motor and the output shaft, so that manual steering is possible and steering operation is not disabled.

Further, according to the above-described configuration, the engaging force between the cylindrical outer ring of the engaging member and the output shaft is increased by compressing the elastic member according to the magnitude of the steering torque, that is, the elastic deformation amount of the elastic body. For example, even when a steep steering is performed under a high load, the engagement member surely engages the cylindrical outer ring with the output shaft,
The assistance from the electric motor can be secured.

Further, in the clutch having the above structure, when the engaging member engages with the inner peripheral surface of the cylindrical outer ring and the multifaceted portion of the output shaft respectively, the rotation of the electric motor causes the inner cylindrical surface of the cylindrical outer ring to rotate. Due to the frictional force between the peripheral surface and the engaging member, the engaging member tries to rotate about its own axis, whereby the transmission of the rotation of the cylindrical outer ring to the output shaft is reduced particularly with a small steering torque (elastic deformation amount of the elastic body). Is unstable (the engagement member rotates between the inner peripheral surface of the cylindrical outer ring and the multi-faced portion of the output shaft = slips), but the above-mentioned means causes the rotation restricting means to engage. Since the rotation of the coupling member is restricted, the rotation of the cylindrical outer ring is reliably transmitted to the output shaft via the engaging member, and the assisting action by the electric motor is reliably performed.

Embodiment An embodiment of the electric power steering device according to the present invention will be described below with reference to the drawings.

In the electric power steering device shown in FIGS. 1 and 2, one end of the input shaft 11 connected to the steering wheel 10 via a connecting member has a hollow stepped tubular shape, and the other end thereof is an output shaft formed by servicing. A pin 15a is connected to one end of a torsion bar 13 connected to 12. As a result, the input shaft 11 is connected via the torsion bar 13 to the output shaft 12 having the pinion 12a that meshes with the rack shaft (not shown), and one end of the output shaft 12 bears on the inner surface of the middle diameter portion 11b of the input shaft 11. Supported by 34, input shaft 1
The steering force applied to 1 is output to the output shaft 12 via the torsion bar 13.
Is being transmitted to. In addition, torch bar
Reference numeral 13 constitutes an elastic body in the present invention.

The input shaft 11 is rotatably supported by a small diameter portion 11a by a bearing 16 press-fitted and fixed to an upper housing 14a on the steering wheel side, and the output shaft 12 is a bearing 17a press-fitted and fixed in a lower housing 14b. , 17b are rotatably supported.

A dust seal 36 is fitted between the small-diameter portion 11a of the input shaft 11 and the upper housing 14a adjacent to the bearing 16, and the medium-diameter portion 11b of the input shaft 11 has a cylindrical shape inside the upper housing 14a. The slider 18 is loosely fitted. The slider 18 is provided with a through hole 18a into which a ball 19 engaged with a spiral groove 11d formed on the outer peripheral surface of the medium diameter portion 11b of the input shaft 11 is fitted. The ring 20 that restricts the movement of the ball 19 in the axial direction of the through hole 18a is a slider.
The outer circumference of 18 is fitted.

A pair of flanges is formed on the outer circumference of the slider 18, and an annular groove 18b is formed between the flanges. Further, on the outer circumference of the slider 18, there is provided a pin 21 fixed to the output shaft 12 and fitted in a long hole 11e formed in a medium diameter portion 11b of the input shaft 11 so that the input shaft 11 can be relatively rotated. An axial hole 18c to be fitted is formed so that the slider 18 can rotate integrally with the output shaft 12 and can freely move in the axial direction of the input shaft 11.

As shown in FIG. 3, a hexagonal hexagonal portion 12b, which is a multifaceted portion in the present invention, is formed on the outer peripheral surface of the output shaft 12. The large diameter portion 11c of the input shaft 11 extends so as to overlap the hexagonal portion 12b of the output shaft 12, and a predetermined gap is formed between the large diameter portion 11c and the hexagonal portion 12b.

As shown in FIG. 3, the large-diameter portion 11b of the input shaft 11 and the hexagonal portion 12b of the output shaft 12 overlap each other so that the hexagonal portions 12b face each other in the neutral state of the steering wheel. Six through holes 11f are provided at evenly spaced positions. A cylindrical roller 22 is inserted into each through hole 11f such that its axial center is aligned with the axial direction of the output shafts 11 and 12, and each of the through holes 11f has an interval of 120 °. Three through holes
A biasing member 33, which is a biasing means in the present invention and is composed of a metal spring (may be rubber or the like), is interposed between each roller 22 and one end surface of the through hole 11f on the rotation direction side of the input shaft 11 in the 11f. However, in each of the remaining three through holes 11f, each roller 22 and the through hole 11f
A biasing member 33, which is a biasing means in the present invention, made of a metal plate spring (may be rubber or the like) is interposed between the input shaft 11 and the other end surface on the rotation direction side. As a result, each roller 22 is pressed against one end face in the circumferential direction of each through hole 11f and is in contact with the surface portion of each hexagonal portion 12b, and the hexagonal portion 12b, the roller 22, an outer sleeve 23 described later, and a biasing member. The numeral 33 constitutes a clutch in the present invention.

Further, outside the large diameter portion 11c of the input shaft 11, the outer sleeve 23 is interposed between the outer sleeve 23 and the outer circumference of the large diameter portion 11b of the input shaft 11 so that a predetermined gap δ is formed between the outer sleeve 23 and the roller 22. Seated bearing 30
And a bearing 31 fixed on the output shaft 12 so as to be rotatable. The outer peripheral surface of the outer sleeve 23 meshes with a helical gear 25 (or a helical gear) fixed to the output shaft 24a of the electric motor 24 via idler gears 26a and 26b (helical gears or a helical gear). Helical gears 23a (or spiral gears) are engraved, and each helical gear (or spiral gear) 23a, 24a, 25 and idler gears 26a, 26b constitute the speed reducer of the present invention.

A case 26 is attached to the upper housing 14a, and the other end of a lever 28 formed of a leaf spring-like metal plate having a ball 27 held at one end is fixed in the case 26. Ball 27 held at one end of lever 28
Is fitted in the annular groove 18b of the slider 18, and a strain gauge (not shown) forming a resistance bridge is attached to the side surface of the lever 28 on the surface coated with an insulating layer. The strain gauge constitutes a well-known strain detection circuit including a bridge circuit, and an electric signal from the strain gauge is input to a control circuit 29, and the control circuit 29 responds to the electric signal from a power source 35 to an electric motor. Controls the current supplied to 24.

Further, in this embodiment, as shown in an enlarged view of a portion in FIGS. 4a and 4b, the outer peripheral surface of the hexagonal portion 12b of the output shaft 12 has an axial width, and the central portion of the roller 22. Is formed with an annular groove 12c, and a ring member 36 made of an elastic material (for example, a rubber material) having a friction coefficient higher than that of steel is fitted in the annular groove 12c. The ring member 36 constitutes the rotation restricting means in the present invention, and in the present embodiment, it is the third member.
In the non-operating state of the clutch shown in the figure, the outer peripheral surface of the roller 22 is in contact with the outer peripheral surface of the hexagonal portion 12b of the output shaft 12 and the ring member 36.

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

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

As a result, the slider 18 is prevented from rotating relative to the output shaft 12 by the pin 21, so that the relative rotation of the input shaft 11, that is, the rotation of the input shaft 11 with respect to the output shaft 12, causes a spiral shape. The ball 19 slides in the groove 12a of the slider 1
A thrust force in the axial direction of the input shaft 11 is applied to 8 to displace the slider 18 in the axial direction according to the rotation direction of the input shaft 11 and the relative rotation of the input shaft 11. The axial displacement of the slider 18 depends on the annular groove 18b.
Via a ball 27 that engages with a lever 28 that holds it
To bend the strain gauge to generate an electric signal according to the relative rotation amount of the input shaft 11 and the output shaft 12. This electric signal is input to the control circuit 29, and the control circuit 29 sends a supply current corresponding to this electric signal from the power supply 35 to the electric motor 24, and the electric motor 24 is rotated in the direction corresponding to the rotation direction of the input shaft 11. The rotation of the electric motor 24 is the helical gear 25 and the idler gears 26a and 26b.
And the helical gear 23a reduces the speed of the outer sleeve 2
Transmitted to 3.

At this time, in the present invention, the clutch is intermittently operated as follows. That is, in FIG. 3, the clutch state is shown when the steering torque detector composed of the slider 18, the ball 19, the ball 27, the lever 28, the strain gauge, etc. is in the neutral state. Gap δ
However, neither the input shaft 11 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 clockwise in FIG. 3, the large diameter portion 11c
Causes the three rollers 22 located on the rotation direction side with respect to the biasing member 33 to move in the rotation direction via the biasing member 33.
The gap δ between the outer sleeve 23 and the outer sleeve 23 disappears,
Is pressed by the wedge action between the inner surface of the outer sleeve 23 and the hexagonal portion 12b of the output shaft 12 to activate the clutch.In this state, the supply of electric current to the electric motor 24 is started and the outer sleeve 23 is input. Start rotating in the same direction as shaft 11. As a result, with the rollers 22 on the rotational direction side of the elastic member 33 being pressed against the inner surface of the outer sleeve 23 and the end surface of the hexagonal portion 12b, the outer sleeve 23 is rotated by the rollers 22.
The steering force applied to the steering wheel 10 is assisted by being smoothly transmitted to the output shaft 12 via. Here, the rotation direction of the outer sleeve 23 is controlled by the control circuit 29 by the input shaft 11
By controlling the rotation of the electric motor 24 in a rotation speed and a rotation direction corresponding to the relative rotation of the output shaft 12 and the output shaft 12, the relative rotation direction of the input shaft 11 coincides with the elastic deformation direction of the torsion bar 13. Is being done. Therefore, the roller 22 on the rotation direction side is strongly pressed against the hexagonal portion 12b by its frictional force, and the rotation force is reliably transmitted.

At this time, the road surface reaction force is large, and when the input shaft 11 is further rotated to the right in order to increase the current supplied to the electric motor 24, the large-diameter portion 11c compresses the urging member 33 and the urging member 33.
On the other hand, the roller 22 on the rotation direction side is to be further moved to the rotation direction side. Therefore, the road surface reaction force is large and the input and output shafts 1
As the relative rotation amount between 1 and 12 increases and the driving force of the electric motor 24 increases, the pressing force of the roller 22 on the rotation direction side by the biasing member 33 is increased in order to increase the engaging force of the clutch. , Engage the clutch securely. Therefore, the input shaft 11
If the roller 22 is simply put in the through hole 11f formed in the large diameter part 11b of the roller or if an appropriate pressing force is not applied to the roller 22, for example, quick steering is performed despite the large resistance on the ground side. When the relative rotation between the input shaft 11 and the output shaft 12 becomes large, the electric motor 24 rotates at high speed,
As a result of the roller 22 on the rotation direction side being suddenly engaged with the output shaft 12 and the outer sleeve 23, the reaction force may cause the roller 22 to bounce off, and the clutch may come off and the steering force may be suddenly increased without assistance. However, in the present embodiment, the roller 22 is urged by the urging member 33 formed of a metal leaf spring to the circumferential one end surface of the through hole 11f, and the larger the relative rotation amount, the rotative direction with respect to the urging member 33. Since the pressing force of the roller 22 on the side becomes large, the engagement of the clutch is secured even in the above case,
Stable assistance is provided.

Further, in the clutch of the present invention described above, the roller 22 includes the inner peripheral surface of the outer sleeve 23 and the multifaceted portion of the output shaft 12.
When the rollers 22 are engaged with each other, the rollers 22 are rotated by the rotation of the electric motor 24, and the outer sleeve 23 is rotated by frictional force between the inner peripheral surface of the outer sleeve 23 and the outer peripheral surface of the roller 22. The rotation of the outer sleeve 23 to the output shaft 12 is unstable when the steering torque is small (the amount of elastic deformation of the torsion bar 13 is small).
Rotation occurs between the inner peripheral surface of 23 and the multi-sided portion 12a of the output shaft 12 =
However, in this embodiment, since the ring member 36 is constantly in contact with the outer peripheral surface of the roller 22, the roller 22 is caused to rotate by the frictional force with the inner peripheral surface of the outer sleeve 23. The desired rotational force can be canceled by the frictional force between the ring member 36 and the roller 22. Therefore, Coro 22
Is the inner peripheral surface of the outer sleeve 23 and the hexagonal portion 12b of the output shaft 12.
The outer sleeve 23 and the output shaft 12 do not rotate relative to each other in the wedge space formed between them and the rotational force of the electric motor 24 is reliably transmitted to the output shaft 12 via the rollers 22 to assist the rotation. The action is surely performed.

As described above, the clutch in the present embodiment rotates the outer sleeve 23 only when the relative rotation of the input shaft 11 and the output shaft 12 is equal to or more than a certain set value and the relative rotation direction and the rotation direction of the outer sleeve 23 match. Is transmitted to the output shaft 12. Therefore, the electric motor 24 is rotated in the direction opposite to the rotation direction corresponding to the relative rotation of the input shaft 11 and the output shaft 12 due to a malfunction of the control circuit 29, and the input shaft 11 is rotated to the right in FIG. Assuming that the outer sleeve 23 is rotated counterclockwise at this time, the rollers 22 on the rotational direction side of the input shaft 11 with respect to the biasing member 33 have the inner peripheral surface of the outer sleeve 23 and the hexagonal portion 12 of the output shaft 12.
b In the state of being in contact with the end face, it is possible to vibrate in the rotation direction of the input shaft 11 in the hole 11f by the frictional force with the outer sleeve 23, and the rotation of the outer sleeve 23 is input and transmitted to the output shafts 11 and 12. No, on the other hand, the rotation of the input shaft 11
A flat width portion formed on the inner surface of the large diameter portion 11c of 11 and a flat width portion formed at the end of the output shaft 12 on the input shaft 11 side and loosely fitted in the flat width portion with a predetermined gap. The mechanical force is transmitted to the output shaft 12 via a manual locking mechanism that transmits the rotational force of the input shaft 11 to the output shaft 12 by engaging with the parts, and enables manual steering.

Further, when the electric motor 24 suddenly becomes a high rotation in the same direction as the rotation direction (right rotation in FIG. 2) corresponding to the relative rotation of the input shaft 11 and the output shaft 12 due to a malfunction of the control circuit 29, The input shaft 11 side becomes a resistance and the urging member 33 is shown in FIG.
On the other hand, the roller 22 on the rotation direction side is pushed in the counter-rotational direction by the illustrated left end surface of the through hole 11f of the input shaft 11 adjacent to the roller 22, and the roller 22 is separated from the inner surface of the outer sleeve 23, and the clutch is deactivated. The rotation of the input shaft 11 is transmitted to the output shaft 12 via the above-mentioned manual locking mechanism, thereby enabling manual steering.

Further, even if the electric motor 24 is caught in a foreign substance and cannot rotate, and thus the outer sleeve 23 cannot rotate, the roller 22 on the rotation direction side with respect to the biasing member 33 in FIG. The rotation of the input shaft 11 is mechanically transmitted to the output shaft 12 via the above-described manual locking mechanism by vibrating against the biasing member 33 by the frictional force with the vibration member 23, or rotating about its own axis. Steering is done. Therefore, for example, in FIG. 3, the input shaft 11 is assisted in the clockwise direction by the electric motor 24, and
24 became unrotatable, and the input shaft was moved in the direction in which it was further assisted.
Even when 11 is rotated, the roller 22 on the rotational direction side vibrates or rotates with respect to the biasing member 33 in FIG. 3, and the rotation of the input shaft 11 is mechanically transmitted through the above-described manual locking mechanism. To be done. Furthermore, even when the input shaft 11 is assisted by the electric motor 24 in the clockwise direction in FIG. 3 and the electric motor 24 becomes unrotatable, and the input shaft 11 needs to be returned in the opposite direction, FIG. , The roller 22 on the rotation direction side (right rotation) with respect to the urging member 33 is pushed in the returning direction (left rotation direction) by the left end surface of the through hole 11f of the input shaft 11 adjacent thereto in the drawing, and the roller 22 is rotated to the outer side. When the clutch is released from the inner surface of the sleeve 23, the clutch becomes inoperative, and the input and output shafts 11 and 12 are rotated with respect to the outer sleeve 23.
Manual steering is possible. In addition, even if the electric motor 24 rotates due to a malfunction of the control circuit 29 while the vehicle is traveling straight, the clutch will react to the input shaft 11 and the output shaft due to the road surface reaction force.
Unless the relative rotation amount with respect to 12 (the elastic deformation amount of the torsion bar 13 = steering torque) exceeds the set value, torque is not transmitted between the outer sleeve 23 and the output shaft 12, so the steering wheel 10 is suddenly cut. There is no such thing.
Furthermore, for example, even when abrupt steering is performed despite a large road surface load, the larger the relative rotation amount between the input shaft 11 and the output shaft 12, the inner surface of the outer sleeve 23 of the roller 22 and the hexagonal portion of the output shaft 12. The pressing force to the end face of 12b increases, and the outer sleeve 23 is well followed by the rapid rotation start, and the engagement with the output shaft 12 is secured. In this embodiment, the mechanical input / output shafts 11, 12 are mechanically driven through the above-mentioned manual locking mechanism.
The steering torque (= the amount of elastic deformation of the torsion bar 13 = the relative amount of rotation between the output shafts 11 and 12) when connecting the clutches is smaller than the steering torque when the biasing member 33 of the clutch is completely compressed. Is set to improve the reliability and durability of the clutch. Further, in this embodiment, the roller 22, the hexagonal portion 12b, and the ring member 36 are brought into contact with each other in the non-operating state of the clutch, but in the non-operating state, the roller 22 secures a gap with the outer sleeve 23 while maintaining the ring member 36.
When the clutch is in the operating state, that is, when the roller 22 is pushed by the large diameter portion 11c of the input shaft 11 when a predetermined relative rotation occurs between the input shaft 11 and the output shaft 12, The ring member 36 may be pushed into the annular groove 12c so that the roller 22 contacts the outer sleeve 23, the hexagonal portion 12b, and the ring member 36.

As described above, according to the present embodiment, the operation of the clutch that interrupts the 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 input shaft 11 is performed. By controlling, the safety and reliability of the electric power steering can be improved, and the device can be downsized. Further, by reliably engaging the clutch roller 22 with the outer sleeve 23 and the hexagonal portion 12b by the ring member 36, the assisting action of the electric motor 24 can be ensured, and the reliability of the clutch can be improved. .

In the above-described embodiment, the cantilever type using the strain gauge is used as the detector for extracting the relative rotation of the input shaft as an electric signal. However, the slip ring, the potentiometer, the photoelectric detector, the magnetostriction are used. It is also possible to adopt a formula detector or the like in the present invention.

In the embodiment described above, the rotation restricting means of the present invention is the annular groove 12c formed on the outer periphery of the hexagonal portion 12b of the output shaft 12.
Although the ring member 36 is fitted to the above, the moving range of at least the large-diameter portion 11c of the input shaft 11 of the roller 22 is at least the diameter of the hexagonal portion 12b in the circumferential direction as shown in FIG. A circular groove 12d is provided in the hexagonal portion 12b, and a circular elastic member 40 made of an elastic material having a higher friction coefficient than steel is provided in the groove 12d.
May be buried.

Further, as a modified example of the rotation regulation means of the present invention, as shown in FIGS. 6a and 6b, the through hole 1 of the large diameter portion 11c of the input shaft 11 is formed.
The rotation restricting means may be constituted by an elastic member 50 made of an elastic material having a friction coefficient higher than that of steel fixed to the end surface of the input shaft 11 facing the 1f roller 22 in the rotation direction. In this case, the clutch does not operate. In this state, it is desirable to bring the rollers 22 into contact with a predetermined preload. Further, as a modified example of the present invention, as shown in FIG. 7, the rotation restricting means is constituted by an elastic member 60 made of an elastic material having a higher friction coefficient than steel fixed to the end of the biasing member 30 on the roller 22 side. May be.

[Effect of device]

According to the present invention, the steering torque detector detects the steering torque according to the elastic deformation of the elastic body connecting the input shaft and the output shaft, and the intermittent operation of the clutch depends 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 direction opposite to the rotation in accordance with the steering torque detected by the steering torque detector due to malfunction of the control means, the clutch does not change to the steering torque detected by the steering torque detector. Depending on the rotation and elastic deformation of the elastic body, the connection and disconnection is controlled, and the rotation of the electric motor is transmitted to the output shaft only when the rotation direction of the reducer by the electric motor matches the elastic deformation direction of the elastic body. However, when the two do not match, the clutch is disengaged and the force is not transmitted between the electric motor and the output shaft, so that manual steering is possible and steering operation is not disabled.
Therefore, the safety and reliability of the electric power steering device can be improved.

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

Further, the present invention further comprises a rotation restricting means for restricting rotation of the engagement member due to rotation of the cylindrical outer ring when the engagement member of the clutch is engaged.

Therefore, when the engaging member engages with the inner peripheral surface of the cylindrical outer ring and the polyhedral surface of the output shaft, the inner peripheral surface of the cylindrical outer ring engages with the engaging member due to the rotation of the cylindrical outer ring due to the rotation of the electric motor. The frictional force of and causes the engaging member to rotate, thereby making the transmission of the rotation of the cylindrical outer ring to the output shaft unstable, especially when the steering torque is small. The rotation of the engaging member is restricted by the means, and relative rotation does not occur between the cylindrical outer ring and the output shaft, and the rotation of the electric motor is reliably transmitted to the output shaft through the cylindrical outer ring and the engaging member. It is possible to improve the reliability of the clutch.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of an electric power steering apparatus according to the present invention, FIG. 2 is a longitudinal sectional view showing details of the embodiment shown in FIG. 1, and FIG. 3 is A in FIG. -A sectional view, FIGS. 4a and 4b are explanatory views of the rotation restricting means shown in FIG. 2, and FIGS. 5, 6a, 6b and 7 are modifications of the rotation restricting means in the present invention. FIG. 10 …… Steering wheel, 11 …… Input shaft, 11d ……
Spiral groove, 11d ... Oval hole, 11f ... Through hole, 12, ... Output shaft, 12b ... Hexagonal part, 12c ... Annular groove, 13 ... Torsion bar, 18 ... Slider, 18c ... Axial direction Long hole, 19 ...
… Ball, 21 …… Pin, 22 …… Roller, 23 …… Outer sleeve, 24 …… Electric motor, 27 …… Ball, 28 …… Lever, 29 …… Control circuit, 33 …… Biasing member, 36… … Ring member (elastic member), 40 …… Elastic member, 50 …… Elastic member, 60
...... Elastic member.

Claims (2)

[Scope of utility model registration request] 1. A steering torque detector for detecting 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 detection signal from the steering torque detector. An electric motor whose rotation is controlled by a control signal from a corresponding control means and whose rotation is transmitted to the output shaft, and the output shaft for rotation of the electric motor which is interposed between the electric motor and the output shaft. In an electric power steering equipped with a clutch for intermittently controlling transmission to a steering shaft, the input shaft is formed in a tubular shape, and both shafts are connected via an elastic body, and the steering torque detector is connected to the elastic body. The steering torque is detected according to the deformation, a plurality of through holes are formed at the end of the input shaft, and a multi-faced portion is formed on the outer peripheral surface of the output shaft to form the multi-faced portion and the through-hole. The output shaft is loosely fitted to the end of the input shaft so as to overlap with each other, and the clutch is arranged concentrically with the input / output shaft with a gap left between the input shaft and the electric motor. And a cylindrical outer ring which is arranged in the through hole and is engaged with the inner peripheral surface of the cylindrical outer ring and the polyhedral portion, respectively, according to the rotation of the input shaft. And an engaging member capable of connecting the output shaft with each other, and an urging means disposed in the through hole for urging the engaging member toward one end face of the through hole in the rotation direction side of the input shaft. And the clutch controls the on-off of the output shaft and the electric motor by elastic deformation of the elastic body, and at the time of engagement of the engagement member of the clutch, rotation of the engagement member by rotation of the cylindrical outer ring. Is equipped with a rotation regulation means for regulating It means the electric power steering apparatus, wherein a made of an elastic member which is fitted in an annular groove formed in the polygonal outer peripheral surface of the output shaft. 2. A steering torque detector for detecting 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 detection signal from the steering torque detector. An electric motor whose rotation is controlled by a control signal from a corresponding control means and whose rotation is transmitted to the output shaft, and the output shaft for rotation of the electric motor which is interposed between the electric motor and the output shaft. In an electric power steering equipped with a clutch for intermittently controlling transmission to a steering shaft, the input shaft is formed in a tubular shape, and both shafts are connected via an elastic body, and the steering torque detector is connected to the elastic body. The steering torque is detected according to the deformation, a plurality of through holes are formed at the end of the input shaft, and a multi-faced portion is formed on the outer peripheral surface of the output shaft to form the multi-faced portion and the through-hole. The output shaft is loosely fitted to the end of the input shaft so as to overlap with each other, and the clutch is arranged concentrically with the input / output shaft with a gap left between the input shaft and the electric motor. And a cylindrical outer ring which is arranged in the through hole and is engaged with the inner peripheral surface of the cylindrical outer ring and the polyhedral portion, respectively, according to the rotation of the input shaft. And an engaging member capable of connecting the output shaft with each other, and an urging means disposed in the through hole for urging the engaging member toward one end face of the through hole in the rotation direction side of the input shaft. And the clutch controls the on-off of the output shaft and the electric motor by elastic deformation of the elastic body, and at the time of engagement of the engagement member of the clutch, rotation of the engagement member by rotation of the cylindrical outer ring. It is equipped with rotation control means for controlling Control means an electric power steering apparatus characterized by consists of the engaging member side fixed to the end portion by an elastic member in the rotational direction side end face or the biasing means of the input shaft of the through hole.