JPH03209026A - Clutching mechanism and motor-driven power steering device - Google Patents

Abstract

PURPOSE:To prevent a cam face from eccentric wear and accomplish stabilized clutching/declutching motions in transmitting the assist force, by locating the center of the circular internal circumferential surface of a driving side member eccentrically from the rotational center of this driving side member. CONSTITUTION:A clutch mechanism 1d is embodies in such an arrangement that the center O2 of the circular internal circumferential surface of a driving side member 6 is eccentrical from its rotational center O1. When this member 6 rotates relative to a following side member 4, the width of a wedge form gap increases or decreases as a whole. Consequently the bite-in position of a cam follower is dislocated in the circumferential direction, and the cam follower contacting position on the applicable cam face will never be in the same place at all times. Thus the cam face is prevented from eccentric wear, and its durability can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a mechanical clutch mechanism and an electric power steering device equipped with this clutch mechanism.

[Conventional technology]

Conventionally, electric power steering devices include a steering force transmission system that transmits steering force from the steering wheel to the steering gear, an electric motor that serves as a power source for auxiliary force that assists the steering force, and a transmission system from the electric motor to the steering gear. It is known that the vehicle is equipped with a clutch mechanism that connects and disconnects the transmission of auxiliary force (driving force of the motor) in response to steering.

Conventionally, electromagnetic clutches were commonly used as the clutch mechanism used in the electric power steering systems mentioned above, but in recent years, mechanical types have been increasingly used due to their high reliability in intermittent operation. ing.

By the way, as the above-mentioned mechanical clutch mechanism, one constructed as shown in, for example, Japanese Utility Model Application Publication No. 59-79467 is known.

That is, this clutch mechanism includes a driving side member (clutch hub) connected to the electric motor via a reduction gear train or the like, and a driven side member (clutch hub) connected to the steering gear.
lower shaft) and multiple circular cross-section cam followers (
The steering wheel basically consists of a steering wheel (ball) and an operating member (cage) connected to the steering wheel via an upper shaft.

The drive side member has a circular inner peripheral surface and is rotatably provided, and the center of the circular inner peripheral surface coincides with the rotation center of the drive side member. The driven member is provided coaxially with the driving member and rotatable relative to the driving member.

Follow! The outer circumferential surface of the 11111 member faces the circular inner circumferential surface of the drive side member, and a gap is formed between the outer circumferential surface and the circular inner circumferential surface that narrows in a pattern from the center toward both ends in the circumferential direction. A cam surface is formed, and the cam surface is flat.

Each cam follower is formed so that its diameter is slightly smaller than the width of the wide part a, and one cam follower is formed in the above gap.
They are inserted movably in the circumferential direction one by one. For this reason,
Each cam follower is separated from the circular inner circumferential surface or cam surface when it is located in the wide part of Fllll+, and when it moves to the narrow part of the gap, it is caught between the circular inner circumferential surface and the cam surface. It has become.

The operating member holds the cam follower and is provided to be rotatable relative to the driven member, and when a relative rotational displacement occurs between the cam follower and the driven member, the cam follower is moved between the circular inner circumferential surface and the cam surface. It is configured to move to a position where it is caught in between, and to a position where it is released when the relative rotational displacement is eliminated.

In the configuration of the clutch mechanism described above, when a relative rotational displacement occurs between the operating member and the driven member, the operating member immediately moves the cam follower to a position where it is caught between the circular inner peripheral surface and the cam surface. As a result, the driving side member and the driven side member are coupled via the cam follower.

Therefore, in an electric power steering system using the clutch mechanism described above, when a steering force is applied to the steering wheel, the clutch mechanism is immediately engaged and the driving force of the electric motor is transmitted to the steering gear. Therefore, the steering force can be assisted with good responsiveness.

[Problem to be solved by the invention]

However, the conventional clutch mechanism has the following problems.

That is, in the configuration of the conventional clutch mechanism, the center of the circular inner circumferential surface of the driving side member provided coaxially with the driven side member coincides with the rotation center of this driving side member, so that the driving side member is connected to the driven side member. Even if it rotates relative to the auxiliary side member, the distance between the cam surface of the auxiliary side member and the circular inner circumferential surface of the driving side member facing it does not change, and a constant wedge-shaped gap is always formed. .

For this reason, there was a problem in that the cam follower placed in the gap always contacted the cam surface at the same position, causing uneven wear of the cam surface.

In view of the above circumstances, the present invention provides a clutch mechanism that can prevent uneven wear on the cam surface and improve the durability of the cam surface, and an electric power steering device equipped with the clutch mechanism. The purpose is to

(Means for Solving the Problems) A clutch mechanism according to the present invention includes a drive side member rotatably provided with a circular inner circumferential surface, and a drive side member coaxially with the drive side member and a drive side member rotatably provided with a circular inner circumferential surface. a driven member rotatable relative to the member; a cam follower having a circular cross section;
an operating member that holds the cam follower and is rotatable relative to the driven member; A cam surface is formed that forms a gap that narrows in a pattern in the circumferential direction between the inner peripheral surface and the cam follower.
It is disposed so as to be movable in the circumferential direction between I, and by moving in the circumferential direction, the circular inner circumferential surface of the driving side member and the cam surface of the driven side member are engaged and released. In a clutch mechanism configured to move the cam follower in the circumferential direction by rotating relative to the driven side member, the operating member is configured to move the cam follower in the circumferential direction by rotating relative to the driven side member. The center is eccentric with respect to the rotation center of this drive side member.

Further, the electric power steering device according to the present invention includes a steering force transmission system that transmits steering force from a steering wheel to a steering gear, an electric motor that serves as a power source of an auxiliary force that assists the steering force, and a steering force transmission system that transmits steering force from a steering wheel to a steering gear. A clutch mechanism is provided that performs on/off transmission of auxiliary force to the steering gear in response to steering, and the clutch mechanism includes a driving side member that works in conjunction with the electric motor, a driven side member that works in conjunction with the steering gear, A cam follower having a circular cross section, and an operation member that holds the cam follower and is provided to be rotatable relative to the driven side member and move relative to the steering wheel, and the driving side member has a circular inner circumferential surface. The driven side member is provided coaxially with the drive side member and is rotatable relative to the drive side member, and the driven side member has the drive side member. A cam surface is formed opposite to the circular inner circumferential surface and forms a gap that narrows in a pattern in the circumferential direction between the circular inner circumferential surface, and the cam follower is disposed in the gap so as to be movable in the circumferential direction. The operating member is configured such that it is engaged between the circular inner circumferential surface of the driving side member and the cam surface of the driven side member and released by moving in the circumferential direction, and the operating member includes: In the electric power steering device configured to move the cam follower in the circumferential direction by rotating relative to the driven member, the center of the circular inner circumferential surface of the driving member is located at the center of the driving member. It is eccentric to the center of rotation.

(Function) According to the above configuration, when the driving side member rotates relative to the driven side member, the distance from the predetermined cam surface to the circular inner circumferential surface facing this cam surface changes, and the wedge-shaped gap is closed. Width increases or decreases overall. For this reason, the biting position of the cam follower shifts in the circumferential direction, and the contact position of the cam follower on the cam surface varies.

〔Example) 1 to 4 show one embodiment of the present invention.

This electric power steering device includes a steering force transmission system 1a that transmits steering force from a steering wheel 2 to a steering gear (not shown), and an electric motor 19 that serves as a power source for an auxiliary force that assists the steering force. This electric motor 1
The clutch mechanism 1d transmits the auxiliary force from the steering wheel 9 to the steering gear only during steering.

The steering force transmission system 1a basically includes the steering wheel 2, a steering shaft 3 connected to a steering gear, and a driving force relay member 4.

The driving force relay member 4 has its boss portion 4a fitted onto the serrations 3C at the tip of the steering shaft 3, and is supported by the steering shaft 3 in a removable manner by fastening a nut 25.

The steering wheel 2 includes a handle 26, an annular operating member 22 coupled to the handle, and a disc 21 attached to the center of the operating member 22. The steering wheel 2 is coupled to the steering shaft 3 so that the disk 21 can be rotated outwardly by the boss 8I34a of the driving force relay member 4, so that the steering wheel 2 can be relatively supported. In this way, the operating member 22 and the driving force relay member 4 are connected to the same @(steering shaft 3
> is arranged so as to be relatively rotatable.

The operation member 22 has a plurality of screw holes 22a formed in the circumferential direction for bolts 71, which will be described later, and a plurality of screw holes 22a are formed in the circumferential direction on the back side of the operation member 22, as shown in FIG. Six protrusions 24 are disposed intermittently. The protrusions 24 are shaped like an arc along the operating member 22, and side surfaces 24a of each protrusion 24 face each other. Further, a protrusion 23 is provided on a part of the circumferential direction of the operating member 22 and protrudes toward the center.
28 is formed, and an end portion 92 of a U-shaped torsion spring 9, which will be described later, is fitted into the projection 23. II 29 is formed, and the contact 13 is held on the protrusion 28 via an insulating material. This contactor 13 is made of a conductive material,
The tip is bifurcated.

As shown in FIGS. 1 to 4, a polygonal cam portion 5 is formed to protrude from the hooked surface side of the driving force relay member 4. As shown in FIGS.

An inner peripheral surface 5b forming an arcuate surface is formed at the center of the polygonal cam portion 5, and a protrusion 52 projecting toward the center is formed integrally with the polygonal cam portion 5 on the inner peripheral surface 5b. This protrusion 52 has a U-shaped torsion spring 9 which will be described later.
A locking groove 59 into which the end portion 91 of is inserted is formed.

A U-shaped torsion spring 9 is provided inside the inner circumferential surface 5b of the polygonal cam portion 5 so as to straddle the steering shaft 3 so that it can be elastically deformed in a plane orthogonal to the axial direction of the steering shaft 3. The arrangement is such that this elastic deformation is not interfered with by the boss portion 4a.

The U-shaped torsion spring 9 has one end 91
is a locking groove 59 formed in the protrusion 52 of the polygonal cam portion 5.
The other end 92 is inserted into the protrusion 23 of the operating member 22.
It is fitted into a locking groove 29 formed in. And 8
In the wA portions 91 and 92, the fixing bins 97 and 98 are respectively located in the recesses 9a. 59a. 9b. 29b, each end 91, 92 is fixed in the locking groove 59, 29 so as not to wobble. As a result, the operating member 22 of the steering wheel 2 and the driving force relay member 4 are connected to each other.
They are connected via a U-shaped torsion spring 9, and when the steering wheel 2 is neutral (when the steering wheel 2 is traveling straight without being steered), the spring force of the U-shaped torsion spring 9 prevents the steering wheel 2 from wobbling. . Moreover, when a steering force is applied to the steering wheel 2 (when the handlebar 26 is operated), the operating member 22 rotates relative to the driving force relay member 4, and the U-shaped torsion spring 9 is deflected according to the amount of deflection. The resulting steering force is transmitted from the handle 26 to the steering shaft 3 via the driving force relay member 4.

A flange 55 is formed on the outer periphery of the driving force relay member 4, and an elongated hole 5 for a bolt 71 (described later) is formed in the inner periphery of the flange 55.
A plurality of 5a are formed in the circumferential direction.

A ring member 6 having a larger diameter than the polygonal cam portion 5 is arranged on the outer peripheral side of the polygonal cam portion 5 of the driving force relay member 4 . This ring member 6 has a circular inner circumferential surface 60a formed inside, and an external gear 60b formed on the outer circumference.

A ball bearing 62a is interposed between the rear surface of the operating member 22 and the arm surface of the ring member 6, and a ball bearing is interposed between the rear surface of the ring member 6 and the outer circumference of the flange portion 55 of the driving force relay member 4. 52a is interposed, whereby the ring member 6 is held coaxially with the operating member 22 and the drive force relay member 4 on the same axis 3 and rotatable relative to these members 22.4. Further, the circular inner circumferential surface 60a of the ring member 6 is formed so that its center 02 is slightly eccentric from the rotation center O of the ring member 6 when the ring member 6 is assembled (see FIGS. (See Figure 7).

A support ring 50 is arranged on the rear side of the driving force relay member 4, and a ball bearing 51 is interposed between the support ring 50 and the driving force relay member 4. A bolt 71 is engaged with this support ring 50, as shown in FIG.
It is threaded into the screw hole 22a of the operating member 22 and secured with a nut 72. As a result, the support ring 50 and the operating member 22 are integrally connected by the bolt 71, the screw hole 22a, and the nut 72, and the ring member 6 is connected to the ball bearing 52a. It is sandwiched between the collar portion 55 of the driving force relay member 4 and the operating member 22 via 62a. Moreover, since the bolt 71 is passed through the elongated hole 55a of the driving force relay member 4, the operating member 22 can only rotate relative to the driving force relay member 4 within the range of the elongated hole 55a. , when attempting to rotate the bolt 71 relative to the edge 55b of the elongated hole 55a. 55c so that the driving force relay member 4 and the operating member 22 rotate together.

As shown in FIG. 1, an interaxial distance retaining plate 16 is externally fitted onto the base end of the boss portion 4a of the driving force relay member 4 via a bearing 16G, and is prevented from coming off by a ring 16d. This inter-axle distance retaining plate 16 has a retaining portion 16a extending outward, and this retaining portion 16a is coupled to the tip of a motor support member 20, and this motor support member 20 is connected to the steering shaft 3 through a bracket 21. The electric motor 19 is fixed to the outer [130] provided on the outer circumferential side of the motor support member 20, and the electric motor 19 is attached to the rear end of the motor support member 20.

A rotating shaft 19a is inserted into the hollow portion of the motor support member 20. The rotating shaft 19a has a base end connected to a drive shaft 191 of the electric motor 19, and a pinion gear 18 is provided at the tip end.
8 meshes with the external gear 6ob. This results in
The driving force of the electric motor 19 is transmitted to the external gear 60b via the rotating shaft 19a. Note that the teeth of the binion gear 18 and the external gear 60b are formed to be inclined in order to ensure smooth meshing and reduce noise.

As shown in FIG. 2, a resistor 14 constituting a steering force detection means is attached to the inside of the inner circumferential surface 5b of the driving force relay member 4, and an electric resistor 14a and a conductor 14b are attached to the upper surface of the resistor 14. is installed.

The electric resistor 14a and the conductor 14b each extend in the tangential direction or circumferential direction (not shown) of an arc centered on the rotation center of the driving force relay member 4, and the electric conductor 14b
are arranged parallel to the electric resistor 14a. The bifurcated tip of the contactor 13 described above is in contact with the electrical resistor 14a and the conductor 14b so as to straddle them. Therefore, when a steering force is applied to the steering wheel 2 and the operating member 22 is rotated relative to the driving force relay member 4, the respective tips of the contacts 13 attached to the operating member 22 are connected to the electrical resistor 14a and Conductor 1
The resistance value corresponding to the position of the contact 13 that slides on the contact 4b and connects the electrical resistor 14a and the conductor 14b changes,
This allows the steering force to be detected.

Further, the electric motor 19 is turned on and off, and the magnitude of the driving force, rotation direction, etc. are controlled based on the detected value from the resistor 14, and when the road surface resistance is generally low, such as when driving at high speed, is controlled to stop in order to improve steering stability.

As shown in FIG. 2, the clutch mechanism 1d includes the aforementioned ring member (driving side member) 6, driving force relay member (driven side member) 4, operating member 22, and a pair of cam followers (left rotation cam follower 7a. ty and a clockwise rotation cam follower 7b).

The outer peripheral surface of the polygonal cam portion 5 of the driving force relay member 4 faces the circular inner peripheral surface 60a of the ring member 6, and a left rotation cam surface 5C and a right rotation cam surface 5d are formed on the outer peripheral surface. There is. The left-turning cam surface 5C and the right-turning cam surface 5d are both formed into curved surfaces curved in the same direction as the circular inner peripheral surface 60a, and the left-turning cam surface 5C is curved in the same direction as the circular inner peripheral surface 60a. The shape is such that the cam surface 5C gradually approaches the counterclockwise direction when viewed from the steering wheel 2 side, and the right rotation cam surface 5d gradually approaches the clockwise direction. As a result, each cam surface 5
Between c, 5d and the inner circumferential surface 60a, there are formed a left rotation gap 64a that narrows in a wedge shape counterclockwise when viewed from the steering wheel 2 side, and a right rotation gap 64b that narrows in a wedge shape clockwise when viewed from the steering wheel 2 side. has been done. Further, the left rotation cam surface 5C and the right rotation cam surface 5d are the left rotation clearance 6.
4a and the right rotation gap 64b are provided adjacent to each other so as to be connected to each other at the wide portion.

The left-turning cam follower 7a and the right-turning cam follower 7b each have a cylindrical shape and a diameter of the gap 64a. 6
4b, and is disposed so as to be movable in the circumferential direction in the left rotation gap 64a and the right rotation gap 64b. Therefore, each cam follower 7a, 7b has a corresponding gap 64a. 64b, each corresponding cam surface 5c
, 5d or the inner circumferential surface 60a, and as shown in FIG.
It is designed to be inserted between a and a.

Cam follower 7a for left rotation and cam follower 7b for right rotation
A pair of mutually connected gaps 64a. 64
A coil spring 8 is interposed in a natural length state or in a slightly compressed state so as to span b.

The side surface 24a of the protrusion 24 of the operating member 22 is arranged to face the circumferential surface of each cam follower 7a, 7b on the side opposite to the coil spring 8, and is in contact with the circumferential surface when the steering wheel 2 is in the neutral position. As a result, when the steering wheel 2 is in the neutral position, each cam follower 7a,
7b and the corresponding cam surfaces 5c, 5d or inner peripheral surface 60a
A minute gap is formed between each cam foor 7a.
, 7b are prevented from being caught between the corresponding cam surfaces 5c, 5d and the inner circumferential surface 60a.

In the above device configuration, when a steering force is applied to the steering wheel 2 and the operating member 22 is rotated, for example, to the left from a neutral state of the steering wheel, the operating member 22 and the driving force relay member 4 are connected to the U-shaped torsion spring 9. Since the operating member 2 is connected to be relatively rotatable via the
2 and the driving force relay member 4, a relative rotational displacement of an amount corresponding to the magnitude of the steering force occurs, and the contact 1
3 is the electrical resistor 14a and conductor 14b of the resistor 14
As a result, the steering force is detected by the resistor 14. As a result, the electric motor 19 is controlled and driven based on the detected value of the resistor 14, the binion gear 18 is rotated, and the ring member 6 is given an appropriate counterclockwise rotational force according to the magnitude of the steering force. (auxiliary power) is given.

Moreover, when the operating member 22 rotates counterclockwise, the clockwise rotating cam follower 7b, which is the upstream side in the rotational direction of the coil spring 8, of the cam followers 7a and 7b that are in contact with the side surface 24a of the protrusion 24 of the operating member 22, first. It is pushed by the side surface 24a and moves in the rotational direction, and this movement causes the coil spring 8 to
is compressed, and due to the restoring force, the left rotation force force 7a on the downstream side in the rotation direction is also pushed in the rotation direction. Simultaneously with the above operation, the side surface 24a of the protrusion 24 that was in contact with the left-turning cam follower 7a also moves in the rotational direction and moves away from (retreats) from the cam follower 7a, so that the left-turning cam follower 7a turns counterclockwise. It moves to the narrow part of the moving gap 64a and gets caught between the left rotating cam surface 5C and the inner circumferential surface 60a of the ring part 416, and the driving force relay member 4 and the ring member 6 rotate as one unit due to the imitation effect. combined in a sloppy manner. That is, as shown in FIG. 7, the clutch mechanism 1d is brought into the engaged state. Thereby, the appropriate rotational force applied to the ring member 6 is transmitted to the steering shaft 3 via the driving force relay member 4, and the steering force is assisted.

Then, when the rotational force applied to the ring member 6 is transmitted to the driving force relay member 4 and there is no relative rotational displacement between the operating member 22 and the driving force relay member 4, a detection value from the steering force detection means is detected. Based on this, the electric motor 19 is controlled to stop rotating, and at the same time, the left rotation cam follower 7a
The counterclockwise rotation gap 64 is in contact with the side surface 24a of the protrusion 24 of No. 2.
It is moved to the wide part of a and the jamming is released.

In this way, the state of simultaneous rotation of the ring member 6 and the driving force relay member 4 is released. That is, as shown in FIG. 2, the clutch mechanism 1d is in a released state. Thereby, when there is no relative rotational displacement, no rotational force is transmitted from the ring member 6 to the driving force relay member 4.

Note that when the operating member 22 is rotated to the right, it operates in the same manner as when it is rotated to the left. However, in this case, a rotational force is applied to the ring member 6 in the right direction, and in the clutch mechanism 1d, the right rotation cam follower 7b connects the right rotation cam surface 5d and the inner peripheral surface 60a of the ring member 6. It becomes stuck in between.

On the other hand, the steering wheel 2 Apply steering force to the operating member 2.
2, the amount of relative rotational displacement of the operating member 22 with respect to the driving force relay member 4 increases, and the bolt 71 may engage with the edges 55b, 550 of the elongated hole 55a. That is, in this case, when the operating member 22 is rotated to the left in FIG. It engages with the edge 55c. In steering when the road resistance is abnormally high as described above, the operating member 22 and the driving force relay member 4 are connected via the bolt 71, and when the steering force is increased thereafter, the operating member 22 and the driving force relay member 4 and 4 will begin to rotate as one body.

In the configuration of the clutch mechanism 1d of this device, the ring member 6
The center 02 of the circular inner peripheral surface 60a is eccentric with respect to the rotation center 01 of the ring member 6.

Therefore, by applying steering force to the steering wheel 2,
When the operating member 22 rotates relative to the driving force relay member 4 and the cam followers 7a or 7b are bitten between the circular inner peripheral surface 60a and the cam surfaces 5C or 5d, each cam follower 7a and each cam surface 5C or each cam follower 7b
When each contact position between and each cam surface 5d is not eccentric (
The contact position will shift from the contact position (in the conventional case). For example, when the operating member 22 is rotated to the left as shown in FIG. 7, the conventional state is shown by a two-dot m line, whereas the configuration of this device is shown by a solid line. That is, even if eccentric, the distance from the rotation center 01 to each cam surface 5c, 5d of the driving force relay member 4 does not change. However, when eccentric, the distance between each cam surface 5c, 5ci and the circular inner circumferential surface 60a facing the cam surface 5c, 5d changes. For this reason, each wedge-shaped Flil64a. 64b have different widths, and as a result, the contact position IB of the cam followers 7a, 7b on the cam surfaces 5c, 5d is shifted from the contact position A in the conventional case.

FIG. 7 illustrates a case where the center 02 is located to the left of the rotation center 01. As the ring member 6 rotates relative to the driving force relay member 4, the center 02 moves on a circumference centered on the rotation center 01 and having a radius of the distance from 01 to 02. When the center 02 moves from the position shown in FIG. 7 to another position, each gap 64a, 64
In b, each cam surface 5c, 5d and this cam surface 5C. 5
Since the distance between the circular inner circumferential surface 60a facing d changes before and after the movement, each space 64a. The width of 64b increases or decreases overall. Therefore, the biting positions of the cam followers 7a and 7b are shifted in the circumferential direction between before and after the movement, and the cam followers 7a on the cam surfaces 5c and 5d are
, 7b start to change their contact positions. In addition, in this device, when the rotation force is not applied to the ring member 6 and the driving force relay member 4 is rotated by the operation of the steering wheel 2, such as when driving at high speed, the ring member 6 is rotated. It may rotate relative to the driving force relay member 4.

According to the configuration of this clutch mechanism 1d, as the ring member 6 rotates relative to the driving force relay member 4, the cam followers 7a, 7 on the cam surfaces 5c, 5d
The contact position of b will change. For this reason, the cam surface 5c
, 5d, the contact positions of the cam faces 7a, 7b are not biased to the same position, but vary, and the cam surfaces 5c, 5d
uneven wear can be prevented.

Note that a single cam follower may serve as both the left-turning cam follower 7a and the right-turning cam follower 7b. Further, the cam surfaces 5c and 5d may be formed flat.

〔Effect of the invention〕

In the clutch mechanism according to the present invention, the center of the circular inner peripheral surface of the drive side member is eccentric with respect to the rotation center of the drive side member. As a result, when the driving side member rotates relative to the driven side member, the width of the wedge-shaped gap increases or decreases as a whole. As a result, the biting position of the cam follower shifts in the circumferential direction, and the contact position of the cam follower on the cam surface is prevented from being biased to the same position. Therefore, uneven wear on the cam surface can be prevented, and the durability of the cam surface can be improved.

Further, since the electric power steering device according to the present invention includes the clutch mechanism described above, it is possible to stably perform the intermittent operation of transmitting the auxiliary force from the electric motor to the steering gear. Moreover, only when the clutch mechanism causes a relative rotational displacement between the operating member and the driven member,
Since the driving side member and the driven side member are configured to be connected immediately, when a steering force is applied to the steering wheel to generate a relative rotational displacement between the operating member and the driven side member, the clutch mechanism are immediately connected, and the driving force of the electric motor is transmitted to the steering gear.

Therefore, the steering force can be applied with good responsiveness and can be assisted only during steering, thereby achieving high reliability.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view showing one embodiment of the present invention, Fig. 2 is a front view with the steering wheel removed, Fig. 3 is an exploded perspective view thereof, and Fig. 4 is the rV- I
VI sectional view, FIG. 5 is a partial vertical cross-sectional view of a connecting portion between the operating member and the support member, FIG. 6 is a front view of the operating member, and FIG. 7 is a front view showing the coupled state of the clutch mechanism. 1a... Steering force transmission system, 1d... Clutch mechanism, 2
... Steering wheel, 4... Driving force relay member (servant side member), 5C, 5d... Cam surface, 6... Ring member (drive side member), 7a, 7b... Cam follower, 19... Electric motor, 22... Operation member, 60
a...Circular inner peripheral surface, 64a. 64b...Gap, 01
... Center of rotation of the driving force relay member, 02 ... Center of the circular inner peripheral surface. Figure 2

Claims (1)

[Claims] 1. A drive-side member having a circular inner peripheral surface and rotatably provided, and a drive-side member provided coaxially with the drive-side member and rotatable relative to the drive-side member. a driven side member, a cam follower having a circular cross section, and an operating member that holds the cam follower and is rotatable relative to the driven side member; A cam surface is formed opposite to the circular inner circumferential surface of the member and forms a gap that narrows in a wedge shape in the circumferential direction between the circular inner circumferential surface, and the cam follower is movable in the circumferential direction into the gap. The operation member is arranged such that the driving side member is engaged with and released between the circular inner circumferential surface of the driving side member and the cam surface of the driven side member by moving in the circumferential direction, and the operating member is In the clutch mechanism configured to move the cam follower in the circumferential direction by rotating relative to the driven member, the center of the circular inner circumferential surface of the driving member is the rotation center of the driving member. A clutch mechanism characterized by being eccentric with respect to the 2. A steering force transmission system that transmits the steering force from the steering wheel to the steering gear, an electric motor that serves as a power source for the auxiliary force that assists the steering force, and an intermittent transmission of the auxiliary force from the electric motor to the steering gear. A clutch mechanism that operates in response to steering is provided, and this clutch mechanism
a driving side member interlocking with the electric motor; a driven side member interlocking with the steering gear; a cam follower having a circular cross section; The drive-side member has a circular inner peripheral surface and is rotatably provided, and the driven-side member is coaxially with and connected to the drive-side member. The driven member is provided with a cam that faces the circular inner circumferential surface of the drive side member and forms a wedge-shaped gap in the circumferential direction between the driven member and the circular inner circumferential surface of the drive side member. The cam follower is disposed in the gap so as to be movable in the circumferential direction, and by moving in the circumferential direction, the cam follower moves between the circular inner circumferential surface of the driving side member and the cam surface of the driven side member. The electric power steering device is configured to engage and release the cam follower, and the operating member is configured to move the cam follower in a circumferential direction by rotating relative to the driven side member. An electric power steering device characterized in that the center of the circular inner circumferential surface of the drive side member is eccentric with respect to the rotation center of the drive side member.