JPH111170A - Electric power steering device - Google Patents

Abstract

(57) [Problem] To be able to positively control the driving of a steering system even in a neutral state of a clutch, and to obtain a good steering feeling in a region where a steering force is small. SOLUTION: A friction engagement type bidirectional clutch mechanism 41, 5 is provided.
1 is formed between an input member 32b connected to the electric motor, an output member 34 arranged coaxially with the input member and connected to the steering system, and an inner peripheral surface of the input member and an outer peripheral surface of the output member. Tapered space 61, engaging member 62 interposed in the tapered space, urging member 65 for urging the engaging member in the taper direction of the tapered space, and positioning of the engaging member A position control member 64 connected to the steering handle, and the position control member is disposed at a position away from the engagement member in the neutral state of the clutch, so that the input / output member in the neutral state is brought into the engaged state. Is what you do.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an improvement of an electric power steering device.

[0002]

2. Description of the Related Art In recent years, electric power steering devices have been frequently used in order to reduce the steering force of a steering wheel to provide a comfortable steering feeling. This type of electric power steering apparatus generates an auxiliary torque according to a steering torque by an electric motor and transmits the auxiliary torque to a steering system via a friction engagement type bidirectional clutch.
For example, there is a technique disclosed in Japanese Patent Laid-Open No. 1-218973 "Electric power steering device". This technology is described in
According to the figure, a cylindrical outer sleeve 23 connected to an electric motor 24 (the number is cited in the official gazette; the same applies hereinafter) via a gear mechanism, and a hexagonal portion 12b connected to a steering wheel. Output shaft 12 is connected to the output shaft 12 via a friction engagement type bidirectional clutch. That is, the assist system including the electric motor 24 and the steering system are connected by the friction engagement type bidirectional clutch.

According to FIGS. 3a and 3b of the publication, a plurality of sets of frictional engagement type bidirectional clutch mechanisms arranged on the same circle are provided with an inner surface of an outer sleeve 23 and a hexagonal portion 1.
Rollers 22 are interposed between the outer surface of 2b and
These rollers 22 selectively switch the outer sleeve 23 and the hexagonal portion 12b into engagement / disengagement (engage / disengage the clutch) as the large-diameter portion 11b of the input shaft 11 moves. Things.

[0004]

According to FIG. 5 of JP-A be Solved by the Invention] In the case of the steering torque T is below a predetermined value T _1, the frictional engagement type bidirectional clutch mechanism is in the release, the assist system from a steering system It is a structure that separates. The state in which the friction engagement type bidirectional clutch mechanism is released is a neutral state of the clutch. When the steering torque is T ₁ or less, because there is no influence of the inertia and frictional resistance of the electric motor 24, the steering wheel is good steering feeling is obtained. However, when the steering wheel is released, no assist torque is transmitted from the assist system to the steering system.

[0005] In recent years, there has been an increasing demand for more positive control of the steering system even in the neutral state of the clutch. For example, it is desired to enable automatic steering control of a steering system in a neutral state of a clutch. Therefore, an object of the present invention is to provide (1) even when the clutch is in a neutral state.
(2) Electric power steering capable of obtaining a good steering feeling (steering feeling) in a region where the steering force is small similarly to the above-described conventional technology. It is to provide a device.

[0006]

In order to achieve the above object, according to the first aspect of the present invention, an electric motor generates an auxiliary torque according to a steering torque, and the auxiliary torque is applied to a friction engagement type bidirectional clutch mechanism. An input member connected to the electric motor, an output member coaxially arranged with respect to the input member and connected to the steering system, and an input member. A tapered space formed between the inner peripheral surface of the member and the outer peripheral surface of the output member, an engaging member interposed in the tapered space, and the engaging member in the taper direction of the tapered space. A biasing member for biasing, and a position control member coupled to a steering handle for positioning the engaging member,
An engagement member that engages or disengages the friction engagement surface of the tapered space by wedge action with the rotation of the position control member, and switches the input / output member to the engagement / non-engagement state. In the electric power steering device, the position control member of the frictional engagement type bidirectional clutch mechanism is disposed at a position away from the engagement member in the neutral state of the clutch, so that the input / output member in the neutral state is engaged. It is characterized in that it was configured to be.

In the neutral state of the clutch, the position control member is located at a position away from the engagement member. All engagement members are
The input / output member is engaged by being pushed by the urging member and engaging with the frictional engagement surface of the tapered space. From such a neutral state, the steering torque for releasing the frictional engagement type bidirectional clutch mechanism by turning the output member with the steering handle is small enough to disengage the engagement member. At this time, since the electric motor is stopped and the friction engagement type bidirectional clutch mechanism is engaged, the steering handle receives a reaction force due to the inertia and frictional resistance of the electric motor. However, the maximum value of the effect does not exceed the steering torque for releasing the clutch. Therefore, the influence of the inertia and frictional resistance of the electric motor is extremely small as compared with the direct electric motor system without the clutch. As a result, a good steering feeling (steering feeling) can be obtained in a region where the steering force of the steering wheel is small. Further, even when the frictional engagement type bidirectional clutch mechanism is in a neutral state, the drive torque (auxiliary torque) of the electric motor can be transmitted to the steering system. Therefore, the steering control can be more positively performed, such as by automatically controlling the steering system in the neutral state of the clutch.

According to a second aspect of the present invention, a torque reduction mechanism is interposed between the frictional engagement type bidirectional clutch mechanism and the steering system so that the auxiliary torque of the electric motor can be reduced by the frictional engagement type bidirectional clutch mechanism, the reduction mechanism, and the steering. It is characterized in that it is transmitted in the order of the system.

As compared with the case where the friction engagement type bidirectional clutch mechanism is connected after the speed reduction mechanism, the auxiliary torque transmitted to the friction engagement type bidirectional clutch mechanism requires an extremely small torque inversely proportional to the reduction ratio of the reduction mechanism. Since the auxiliary torque is small, the transmission capacity of the clutch can be reduced, and as a result, the friction engagement type bidirectional clutch mechanism can be reduced in size and weight.

According to a third aspect of the present invention, the frictional engagement type bidirectional clutch mechanism is provided in a plurality of sets arranged on the same circle, and at least one of the plurality of sets of the frictional engagement type bidirectional clutch mechanism is replaced with another. An early release clutch that is disengaged at a timing earlier than the clutch mechanism of (1).

If only one set of clutch mechanisms is disengaged at an early timing, the other clutch mechanisms lose their balance and exert a resultant force in the direction of disengagement, so that the frictional force is reduced and disengagement is achieved with a small disengagement force. Therefore, the clutch mechanism can be reliably released with a smaller release force than when all the clutch mechanisms are released at once.

According to a fourth aspect of the present invention, an output shaft is provided on a steering system, and an output member is mounted on the output shaft so as to be movable in a radial direction.

Since the output member is attached to the output shaft so as to be movable in the radial direction, when a part of the plurality of engagement members engaged with the output member comes off, the balance of the force for pushing the output member by the engagement member is reduced. Crumble. When the balance is lost, the output member is pushed by one of the other engagement members and moves in the radial direction. As a result, the frictional force between the output member and the other engagement member is reduced, and the engagement is released more stably. In this way, when some of the clutch mechanisms are released, the other clutch mechanisms are released more stably, so that even when the electric motor rotates for some reason, all the clutch mechanisms are released at once. The release can be reliably performed with a release force smaller than the release.

The invention according to claim 5 is characterized in that a preload is applied to the output member in the moving direction with respect to the output shaft by providing an elastic member for pressing the output member against the output shaft.

The output member moved in the radial direction can be automatically returned to the original neutral position by the elastic force of the elastic member after all the clutch mechanisms are released. For this reason, the clutch mechanism can be disengaged with a small disengaging force as many times as possible, and the clutch function can be stabilized.
Productivity increases.

According to a sixth aspect of the present invention, even when the position of the engagement member in the tapered space changes with the radial movement of the output member, the wedge angle at the contact portion of the engagement member is substantially constant. The taper angle correcting portion is formed on the frictional engagement surface so as to be as follows.

For any reason, even if the output member is eccentric with respect to the input member, and the position of the engaging member in the tapered space changes due to the eccentricity, the taper angle correcting portion can be connected to the frictional engagement surface. Correction is made so that the wedge angle with the engaging member is substantially constant. As a result, even if the position of the engaging member in the tapered space changes with the eccentricity of the output member, the wedge angle is substantially constant, and the wedge action does not change. Therefore, the release force for releasing the engagement member from the tapered space does not increase, and the proper release force can be always maintained.

The invention according to claim 7 is characterized in that a part of the tapered space portion is expanded so that the engaging member can be separated from the frictional engagement surface when not engaged.

Since a part of the tapered space is expanded, the gap between the expanded part and the engagement member when not engaged is large. For this reason, since the engagement member at the time of non-engagement can be reliably separated from the friction engagement surface, the amount of radial movement of the output member can be increased, and as a result, the clutch mechanism is reliably released. be able to.

[0020]

Embodiments of the present invention will be described below with reference to the accompanying drawings. The drawings should be viewed in the direction of reference numerals. FIG. 1 is an overall configuration diagram of an electric power steering apparatus according to the present invention. An electric power steering apparatus 1 includes a steering torque detecting unit 3 that detects a steering torque of a steering system generated by a steering handle 2.
A control unit 4 for generating a control signal based on the detection signal of the steering torque detection unit 3; an electric motor 5 for generating an auxiliary torque corresponding to the steering torque based on the control signal of the control unit 4; 5, a torque transmission means 6 for transmitting an auxiliary torque of 5 to a steering system, and a mechanical clutch 40 for steering wheels (steered wheels) 9, 9 via a pinion 7 and a rack 8a.

FIG. 2 is a block diagram of the control means according to the present invention.
and a control signal generating means for generating a control signal for driving the electric motor 5 based on the signal Ta from the target auxiliary torque determining means 4a. 4b, and an electric motor driving unit 4c for driving the electric motor 5 based on the signal of the control signal generating means 4b.

FIG. 3 is an enlarged sectional view of a main part of the electric power steering apparatus according to the present invention. The electric power steering apparatus 1 includes the steering handle 2 (see FIG. 1).
A torsion bar (elastic member) 13 inserted into the input shaft 11 and having an upper portion connected to the input shaft 11 by a pin 12;
A main steering system is constituted by an output shaft 15 having a pin 14 attached to a lower portion of the shaft and a pinion 7 engraved at a lower portion. The torsion bar 13 is a member that literally generates a torsion angle with respect to the torque, and generates a relative torsional displacement between the input shaft 11 and the output shaft 15.

The steering torque detecting means 3 includes an input / output shaft 1
The steering torque of the steering system is detected by detecting the relative torsion angle between 1 and 15, and in this embodiment, a potentiometer is used. The potentiometer includes a detection body 21 having a resistance element (not shown) and a sliding contact that moves along the resistance element, and a rod-shaped operating element 22 rotatable to operate the sliding contact in the detection body 21. And a torsion spring 23 for urging the actuator 22 in one of the rotational directions. The potentiometer bolts the detection main body 21 to the lower outer peripheral surface of the input shaft 11,
The tip of the actuator 22 is used by hooking the engagement groove 15 a on the upper outer peripheral surface of the output shaft 15. Since the actuator 22 is always pressed against one side wall of the engagement groove 15a by the torsion spring 23, there is no play in the rotation direction. The detection main body 21 includes an electric cable 24.
Is wound on the cable reel 25 on the input shaft 11 side by a plurality of turns (for example, about 3 turns) and then connected to the connector 27 on the housing 26 side.

The wheel 32 of the torque transmitting means 6 described later
Is a thick cylindrical member rotatably supported on the upper portion of the output shaft 15 via a bush 33, and a gear portion 32a and an input member 32b are formed on the cylindrical member in order from the bottom in the axial direction. is there. The mechanical clutch 40 includes the input member 3
2b, and its sectional configuration is shown in FIG.
Will be described in detail. The rack 8a is engraved on a rack shaft 8 extending in the front and back directions in FIG. The input shaft 11, the torsion bar 13, and the output shaft 15 are coaxial. In the figure, 36, 37 and 38 are bearings, and 39 is a dust cover.

FIG. 4 is a sectional view taken along line 4-4 of FIG. The torque transmitting means 6
This is a worm gear reduction mechanism including a worm 31 coupled to an electric shaft (output shaft of the electric motor) 5 a of the electric motor 5 and a wheel 32 rotatably supported on the output shaft 15. As a result, the input member 32b shown in FIG. Therefore, in FIG. 3, the rack 8a is driven via the pinion 7 with the combined torque obtained by adding the auxiliary torque from the electric motor 5 to the steering torque of the steering system (input shaft 11 → torsion bar 13 → output shaft 15). The electric motor 5 was bolted to the housing 26.

FIG. 5 is an exploded perspective view of a main part of the electric power steering apparatus according to the present invention. The input shaft 11 is at the lower end,
An annular position control means 63 which is a component of the mechanical clutch 40 is serrated and fitted.
Is formed integrally with three position control members 64 extending downward (... denotes a plurality, the same applies hereinafter). Therefore, the position control members 64 are connected to the steering handle 2 shown in FIG. The output shaft 15 has an output member 34 connected to the upper end of the base, and the output member 34 is a member arranged coaxially with the input member 32b.

FIG. 6 is a sectional view taken along line 6-6 of FIG. The housing 2
6 is omitted. The mechanical clutch 40 is connected to the electric motor 5.
This is an assembly of a plurality of friction engagement clutch mechanisms that transmit the auxiliary torque of the electric motor 5 to the steering system only when the action direction of the auxiliary torque (see FIG. 3) matches the steering direction of the steering system. Specifically, the mechanical clutch 40
Is the arrow X direction of the input member 32b (counterclockwise direction in the figure)
, And three sets of second clutch mechanisms 51... Engaging in the reverse rotation direction are alternately arranged on the same circle. The second clutch mechanisms 41,..., 51 are one-way clutches composed of friction engagement type clutch mechanisms. The combination of the first clutch mechanism 41 and the second clutch mechanism 51 adjacent to each other is 1
There are a total of three sets of frictional engagement type bidirectional clutch mechanisms.

More specifically, the first and second clutch mechanisms 4
, 51 ... engage the input member 32b and the output member 34 with the tapered spaces 61 formed between the input / output members 32b, 34 interposed therebetween. Columnar engaging members 62 and position control members 64 for positioning these engaging members 62.
And the engaging members 62 toward these position control members 64.
(A biasing member 62 is biased in the taper direction of the tapered space portion 61) as a biasing member.
5 ...

The output member 34 has a generally tapered cross-sectional shape (a shape in which three sides of an equilateral triangular cross-section with corners cut off are arc-shaped). The tapered space portions 61 are space portions formed between the circular inner peripheral surface of the input member 32b and the polygonal outer peripheral surface of the output member 34, and having a tapered peripheral end. The position control members 64 are members that are rotatably arranged at equal pitches on the same circle between the input member 32b and the output member 34 while being separated from each other. The mechanical clutch 40 having such a configuration includes a position control member 64.
The input member 32b and the output member 34 are engaged with each other by engaging members 62 which engage or disengage with the frictional engagement surfaces of the tapered space portions 61 by wedge action with the movement (rotation) of the input member 32b. It selectively switches to non-engagement and transmits the auxiliary torque from the electric motor 5 to the output shaft 15.

The first and second clutch mechanisms 41
, 51 ..., each specific set (hereinafter referred to as "specific first
Second clutch mechanisms 41A, 51A ". ) Is an early release clutch which is disengaged earlier than the other sets. Specifically, the position control members 64.
They are arranged at the same pitch on the same circle, but the claws of the specific first and second clutch mechanisms 41A and 51A are
, 51 ... longer (L ₁ > L ₂ ).

More specifically, the position control members 64 are arranged such that their centers O _{1 to} O ₃ are output members 34 having a substantially equilateral triangular cross section.
Are matched to the respective corners. And two position control members 64 (specific position control members 64A, 64A)
The center O _1, part of the O ₂ Who face to face with each other (referred to as "long nails".) Arc length L ₁ and the other part of ( "short nails"
Called. Greater than the arc length L ₂ of). The long claws are the engaging members 62 of the specific first and second clutch mechanisms 41A, 51A.
Make positioning. The other position control member 64 is L ₂ , L ₂ having the same arc length on both the left and right sides from the center O ₃ ,
It is the same as the arc length of the short claw.

And, all the position control members 64...
In the neutral state of the first and second clutch mechanisms 41, 51, by arranging the first and second clutch mechanisms 41, 51 at positions away from the engagement members 62,
The input / output members 32b and 34 in the neutral state are configured to be engaged. Specifically, in the clutch neutral state shown in this figure, the arc lengths L ₁ and L ₂ are set such that the ends of all the position control members 64 are separated from the engagement members 62.

The output member 34 is connected to the input member 32.
It is mounted so as to be movable in the radial direction relatively to b. Specifically, the output member 34 is attached to the output shaft 15 so as to be movable in the radial direction. More specifically, the output member 34 is connected to the specific first clutch mechanism 41A and the specific second clutch mechanism 51A. Intermediate position (specific position control member 64
(A, 64A).

More specifically, an elliptical or elliptical through hole 34a is formed in the output member 34, a circular output shaft 15 is fitted into the through hole 34a, and the pin 14 is inserted through the longitudinal axis of the through hole 34a. An elastic member (compression spring or the like) is attached to the pin 14.
The elastic member 35 presses the through hole 34 a of the output member 34 relatively to the output shaft 15. That is, the elastic member 35 is interposed between the outer peripheral surface of the output shaft 15 and the surface of the through hole 34a in the longitudinal direction, and the elastic direction of the elastic member 35 is changed in the moving direction of the output member 34 (the longitudinal axis of the through hole 34a). Direction), and the output member 34 is pressed against the output shaft 15. Thereby, the output shaft 15
, A preload in the movement direction can be applied to the output member 34.

Further, a part of the tapered space portions 61 of one set of clutch mechanisms (specific first clutch mechanism 41A and specific second clutch mechanism 51A) is expanded to frictionally engage the engaging members 62 when disengaged. It can be separated from the engagement surface. Specifically, a relief recess 34c is formed in a part of the engagement surface 34b of the polygonal outer peripheral surface of the output member 34, and the engagement members 62, 6 of the specific first / specific second clutch mechanisms 41A, 51A.
2 can be separated from the friction engagement surface.

Further, one set of clutch mechanisms (specific first clutch mechanism 41A or specific second clutch mechanism 51)
When only A) is released, the polygonal outer peripheral surface of the output member 34 that engages with the engaging members 62 of the other clutch mechanisms 41. And That is, when the output member 34 moves in the radial direction, the outer peripheral surface of the polygon is formed to be easily detached from the engaging members 62. Therefore, when one set is released, the output member 34 can move in the radial direction without any restriction.
Accordingly, only by releasing one set of clutch mechanisms, the other clutch mechanisms can be released reliably.

FIG. 7 is a detailed view of part 7 of FIG.
It is the figure which expanded the frictional engagement surface of tapered space part 61 of clutch mechanism 41A. The first and second clutch mechanisms 4
The frictional engagement surfaces of the tapered spaces 61 in 1, 51 are “the inner peripheral surface 32 c of the input member 32 b (hereinafter, referred to as“ input-side frictional engagement surface 32 c ”) and the output member. 3
4 (hereinafter, referred to as an “output-side friction engagement surface 34b”).

When the output member 34 is coaxial with the input member 32b, the engagement member 62 engages with the frictional engagement surface of the tapered space 61 at the position shown by the imaginary line in the figure. Contact between the friction engagement surface 32c and the engaging member 62 on the input side at this time is P _1, the contact between the friction engagement surface 34b and the engaging member 62 of the output side is P _2.

As described above, the output member 34 is connected to the input member 3
The position of the engaging member 62 in the tapered space 61 is changed due to a poor return of the output member 34 or a manufacturing error of each member, though it is movable in the radial direction relative to 2b. To cope with this, a taper angle correcting portion 34d is formed on the frictional engagement surface of the tapered space portion 61 of the specific first clutch mechanism 41A, and the taper angle correcting portion 34d , The wedge angle θ at the contact portion of the engaging member 62 is substantially constant.

Specifically, the flat friction engagement surface 3 on the output side
4b, a slope is formed which is inclined in the direction in which the taper of the tapered space portion 61 widens (to the right in this figure), and preferably, the slope is an arc surface having a predetermined radius of curvature r. The proximal end of the arcuate surface is a position slightly displaced in the taper direction opposite to the direction from the contact point P _2. Further, the wedge angle θ at the contact portion of the engaging member 62 is obtained even if the position of the arc center and the diameter of the engaging member 62 change (even if the diameter changes due to dimensional tolerance or wear).
Is set appropriately so as to be substantially constant. That is, the above-described arc surface is used as the taper angle correction unit 34d. Similarly, the specific second clutch mechanism 51A also has a taper angle correction section 34d on the friction engagement surface.

Next, the operation of the taper angle correcting section having the above configuration will be described with reference to FIG. FIGS. 8A to 8C are operation diagrams of the taper angle correction unit according to the present invention, and schematically show the specific first clutch mechanism 41A and the taper angle correction unit 34d. (A) is a comparative example, in which the input member 32 is used.
When the output member 34 is coaxial with b, the first flat surface of the output member 34 (output side frictional engagement surface 34b) is at the lower level indicated by the thick solid line. Contact between the friction engagement surface 32c and the engaging member 62 on the input side at this time is P _1,
Contact the first surface and the engaging member 62 is P _2. Further, the wedge angle at the contact portion of the engaging member 62 is theta _1.

On the other hand, the output member 3 is
4 moves relatively radially, so that the first surface moves to the upper level indicated by a thin solid line. As a result, the engaging member 62 moves the taper direction opposite the direction of the tapered space 61 (the right direction in this figure), is also moved in the same direction position of the contact point P _1. Therefore, the inclination angle of the tangent to the friction engagement surface 32c of the input side contacts P ₁ position is reduced.
Since the inclination angle is small, the wedge angle θ _{2 at the} contact portion of the engagement member 62 is small. Therefore, the wedge angle θ ₂ after the movement is
According to the distance that the output member 34 has moved in the radial direction, the wedge angle θ ₁ at the original position becomes smaller. When the wedge angle theta ₂ decreases intensified wedge action, releasing force for releasing the engagement member 62 from the tapered space 61 is increased.

(B) shows the basic theory of the present embodiment.
This is an improvement of the above (a). A second surface is provided in the direction in which the taper of the tapered space portion 61 widens (to the right in the drawing) with respect to the first surface after the movement, and this second surface is
2 and the second surface and the frictional engagement surface 32 on the input side.
The wedge angle of the engaging member 62 engaged between the c and theta _3, and the wedge angle theta ₃ so that the wedge angle theta ₁ and the same angle. Therefore, despite the fact that the first surface has moved,
The wedge angle does not change. Since the wedge angle does not change, the wedge action does not change, and the engagement member 6 is moved from the tapered space 61.
The release force for releasing 2 does not increase.

(C) shows this embodiment, and (b)
Is a concrete example of An arc surface inclined in the direction in which the taper of the tapered space portion 61 widens was formed in the middle of the flat first surface on the output side, and this arc surface was defined as a second surface. Input member 3
When the output member 34 moves relatively in the radial direction (upward in the figure) with respect to 2b, the position of the engagement member 62 in the tapered space 61 changes with this relative movement. The second surface holds the engaging member 6 even when the position of the engaging member 62 changes.
2 is an arc surface in which the wedge angle at the contact portion is substantially constant. Proximal end of the arcuate surface is a position slightly displaced in the taper direction opposite to the direction from the contact point P _2.

As described above, even if the output member 34 moves in the radial direction relative to the input member 32b, the wedge angle is always substantially constant, so that the wedge action does not change, and the engagement from the tapered space 61 is performed. The release force for releasing the member 62 does not increase, and the proper release force can always be maintained. In the present embodiment, the second surface is a taper angle correction unit 34d, and the taper angle correction unit 34d always maintains the clutch release force of the specific first clutch mechanism 41A at an appropriate release force. Can be. Note that the specific second clutch mechanism 51A also performs the same operation.

Next, the principle of switching from the neutral state in the mechanical clutch 40 having the above configuration will be described with reference to FIG. FIGS. 9A to 9D are switching principle diagrams of the mechanical clutch. For convenience of explanation, in this figure, the engaging member of the first clutch mechanism 41 is referred to as “first engaging member 62F”, and the engaging member of the second clutch mechanism 51 is referred to as “second engaging member 62R”. .

First, the first and second clutch mechanisms 4 are operated by the steering torque of the steering handle 2 (see FIG. 1).
The principle of switching 1, 51 will be described. 6 and 7 above
As described above, the frictional engagement surface 32c on the input side is circular, while the frictional engagement surface 34b on the output side is a generally flat surface composed of three sides of an equilateral triangular section with corners cut off. It is. Input / output side frictional engagement surfaces 32c, 34b
The tapered space 61 formed therebetween is a space having a wide width at the center in the circumferential direction and tapered at both ends in the circumferential direction.

In (a), the first and second clutch mechanisms 41 and 51 are in a neutral state in which both are engaged. Electric motor 5
(See FIG. 3) has been stopped, so that the input member 32
b is also almost stopped. In this neutral state, the first and second engagement members 62F and 62R
Of the frictional engagement surfaces 32c, 3 on the input / output side
4b is engaged by wedge action. That is, the frictional engagement surfaces 32c of the input-output side, to the 34b, the first engagement member 62F engages with the point Q ₁ and the point Q _2, the second engagement member 62R is the point Q ₃
And to engage in a point Q _4. Hereinafter, these points Q ₁ , Q ₂ ,
Q ₃ and Q ₄ are referred to as “engagement points”. Rotation path of the outer peripheral surface of the output member 34 can be a represented by line K _1, can represent the rotational locus of the engagement point Q ₂ and the engagement point Q ₄ with a line K _2. And
Since the frictional engagement surface 34b on the output side is generally flat, in the engagement point Q ₂ and the engagement point Q _4, it intersects the rotation locus K _2.

When the output member 34 is turned in the direction of the arrow X by the steering torque of the steering handle 2, the tapered space portion 61 becomes wider with respect to the first engagement member 62F as it is rotated. At this time, the first engagement member 62F is in a direction to escape from the tip of the tapered space portion 61 in the wide direction, so that the steering torque from the output member 34 cannot be transmitted to the input member 32b.

When the output member 34 is turned by the steering handle 2 in the direction of arrow X, the tapered space 6
1 becomes narrower with rotation with respect to the second engagement member 62R. That is, the output side frictional engagement surface 34b rotates in the direction into which the second engagement member 62R is engaged. Therefore, the engagement of the second engagement member 62R is not released.
As a result, the second engagement member 62R can transmit the steering torque from the output member 34. By the way, the electric motor 5 and the input member 32b are connected by the torque transmitting means 6 (see FIG. 3). Since the torque transmitting means 6 is composed of a worm gear reduction mechanism, the frictional resistance is extremely large. Therefore, while the electric motor 5 is stopped, the second engagement member 62R
Is locked, the output member 34 does not rotate. The reaction force associated with the frictional resistance of the torque transmitting means 6 at this time acts on the steering handle 2 via the output member 34.

Thereafter, when the steering torque of the steering handle 2 is increased, the displacement angle of the position control member 64 in the direction of the arrow X increases. Then, in (b), the position control member 64 at the right end of the drawing moves the second engagement member 62R to the arrow X.
Direction to release the engagement. Steering torque at this time (switching torque) is T _10. At this point, it is possible by the steering torque T ₁₀ of the steering wheel 2, turn the output member 34.

[0052] Immediately thereafter, (c), the from the motor 5 to the input member 32b, by so that the arrow X direction of the auxiliary torque T ₂₀ is transmitted, assist torque T ₂₀ is the input member 32 b → first engagement member 62F acts on the path of the output member 34. Thus, the output member 34 and the output shaft 15 (see FIG. 6) is the combined torque obtained by adding the assist torque T ₂₀ of the electric motor 5 to the steering torque T ₁₀ of the steering system, the arrow X
Rotate in the direction.

As is clear from the above description, the motor 5
Is in a stopped state, so that the driver operating the steering handle 2 can use the electric clutch 5 via the mechanical clutch 40.
And the reaction force due to the inertia, viscous resistance and frictional resistance of the torque transmitting means 6, the maximum value of the reaction force is
· Second required to release only one of the clutch mechanism 41 and 51, not a steering torque T ₁₀ or more. Therefore, the influence of the inertia and the frictional resistance of the electric motor 5 and the torque transmitting means 6 is extremely small as compared with the direct electric motor system without the clutch. As a result, a good steering feeling (steering feeling) can be obtained in a region where the steering force of the steering wheel 2 is small.

Next, the principle of automatically switching the first and second clutch mechanisms 41 and 51 based on the motor torque of the motor 5 will be described. In (d), the first and second clutch mechanisms 41 and 51 are in the engaged neutral state. In this neutral state, the first and second engagement members 62F, 62R are connected to the input / output side frictional engagement surfaces 32c, 34b in the same manner as in the switching principle diagram by the steering torque shown in (a). Q
_1, engages _{Q 2, Q 3, Q 4} .

In this state, the input member 32b is
To, when convey motor torque in the arrow X direction, the electric motor torque T ₃₀ in engagement point Q _1, Q ₃ is applied. In order for the second engagement member 62R to be disengaged from the input / output side friction engagement surfaces 32c and 34b, the second engagement member 62R needs to be slightly displaced in the direction of the arrow X. However, since the first engaging member 62F is in the engaged state, the second engaging member 62R cannot be displaced. By the way, when the input member 32b is rotated in the direction of the arrow X, the tapered space portion 61 becomes wider with respect to the second engagement member 62R with the rotation. At this time, since the second engagement member 62 </ b> R escapes from the tip of the tapered space 61 in the wide direction, the motor torque cannot be transmitted to the output member 34. As a result, the motor torque T ₃₀ acts on the output member 34 in the path of the input member 32 b → first engaging member 62F. Therefore, the output member 34 and the output shaft 15
(See FIG. 6) is the motor torque T ₃₀ of the motor 5 is rotated in the arrow X direction.

Next, the operation of the mechanical clutch 40 having the above configuration will be described with reference to FIGS. FIG.
13 to 13 are operation diagrams of the mechanical clutch according to the present invention. In FIG. 1, when the steering wheel 2 is not steered, the control device 4 does not output a control signal (assist command signal) because there is no signal from the steering torque detecting means 3.
Therefore, the electric motor 5 is in a state where no electric motor torque (auxiliary torque) is generated. In this state, all the position control members 64 shown in FIG. 10 are separated from the engagement members 62, so that the first and second clutch mechanisms 41, 51,.
Are in the engaged neutral state. That is, all the engaging members 62 are in an engaged state in which they are merely pressed against the frictional engagement surfaces of the tapered spaces 61 by the compression springs 65.

Next, when the steering torque of the steering handle 2 is small and the motor 5 does not generate a motor torque (auxiliary torque), the position control members 64... Connected to the input shaft 11 (see FIG. 3) and the output member 34 Phase hardly changes. In this case, each position control member 64.
However, for example, it slightly moves in the counterclockwise direction in this figure, but does not push the engaging members 62.

Thereafter, when the steering torque of the steering handle 2 becomes equal to or more than a predetermined value, the first clutch mechanisms 41 and the second clutch mechanisms 51 operate based on the principle described with reference to FIGS. 9B and 9C. I do. That is, as shown in FIG. 11, the position control members 64 move in the direction of the arrow X, for example, and engage members 62 of the second clutch mechanisms 51.
Is disengaged. At this time, since the steering torque is large, the electric motor 5 generates an auxiliary torque. As the electric motor 5 rotates, the input member 32b rotates in the arrow X direction. Since the first clutch mechanisms 41 are engaged, the electric motor torque (auxiliary torque) from the electric motor 5 is steered along the path of the input member 32b → the first clutch mechanism 41 ... → the output member 34 → the pin 14 → the output shaft 15. It is transmitted to the system. As a result, the output shaft 15 is rotated in the direction of the arrow X by the combined torque obtained by adding the auxiliary torque of the electric motor 5 to the steering torque of the steering system (input shaft 11 → torsion bar 13 → output shaft 15).

Thereafter, if the transmission of the auxiliary torque by the electric motor 5 is continued for some reason, the first clutch mechanisms 41 are released as follows. When the steering handle 2 is rapidly steered in the reverse direction, all the position control members 64 turn in the direction opposite to the rotation direction of the input member 32b (the direction of the arrow Y) as shown in FIG. The specific position control member 64A is preceded by the other position control members 64... Before the right adjacent engagement member 62 (for convenience, the “engagement member 62A”).
Called. ), And extrudes against frictional force and urging force. Therefore, the engagement member 62A releases the engagement of the specific first clutch mechanism 41A.

By the way, at the moment when the steering handle 2 is rapidly steered in the reverse direction, the engaging members 62 of all the second clutch mechanisms 51 are still in the released state as shown in this figure. The second clutch mechanism 5 does not need to be turned at the time of rapid steering.
The engaging members 62 of the...
, And the second clutch mechanisms 51 are also in a non-engaged state. The other position control members 64 are not in contact with the engagement members 62. At this time, the vectors indicated by arrows Z ₁ and Z ₂ in the figure are continuously applied from the other engaging members 62 to the output member 34, and the output member 34 is acted on based on the resultant force of these vectors. unbalanced load indicated by the arrow Z ₃ in FIG acts. As a result, the output member 34 slightly moves toward the specific position control member 64A with the pin 14 as a guide against the elastic force of the elastic member 35. Therefore, the engaging forces of the other engaging members 62 are weakened. Immediately thereafter, the other position control members 64 contact the engagement members 62 to release the engagement.

As a result, the other first clutch mechanisms 41 are also released. The output member 34 automatically returns to the neutral position shown in FIG. 10 by the elastic force of the elastic member 35. in this case,
Since no frictional force is generated in the other engagement members 62, the release force pressed by the other position control members 64 is
It only needs to be small enough to withstand the urging force of. In this way, even if the rotation of the input member 32b is continued, the engagement of the three sets of first clutch mechanisms 41... Can be reliably released.

The second clutch mechanisms 51 operate in reverse to the first clutch mechanisms 41, and will be described with reference to FIGS. 10 to 12 when the steering handle 2 is steered in the reverse direction. In the same operation as the action
It can be switched to non-engagement.

Further, as shown in FIG.
The gap between the outer peripheral surface and the engaging member 62A is
It is big by the depth of. For this reason, the engagement member 62A can be reliably separated from the frictional engagement surface, and the radial movement amount of the output member 34 can be increased accordingly. Therefore, the first and second clutch mechanisms 41, 51,.
Can be more quickly and reliably released.

Incidentally, the first and second clutch mechanisms 41
, 51... Are in a neutral state as shown in FIG. 10, the steering system can be automatically controlled based on the principle described with reference to FIG. 9D. That is, when the electric motor 5 generates the electric motor torque under the control of the control means (not shown), the input member 32 shown in FIG.
b rotates in the direction of the arrow X, for example. According to the principle described with reference to FIG. 9D, the second clutch mechanisms 51 cannot transmit the motor torque. For this reason, the motor torque from the motor 5 is changed from the input member 32b to the first clutch mechanism 41.
The power is transmitted to the steering system through the path of the output member 34 → the pin 14 → the output shaft 15. As a result, the output shaft 15 is rotated in the direction of the arrow X by the auxiliary torque of the electric motor 5.

In this state, if the electric motor torque of the electric motor 5 is reduced to substantially zero, the first and second clutch mechanisms 41, 51,.
Returns to the state shown in FIG. Also, by generating a reverse motor torque from the motor 5, the first
The second clutch mechanisms 41, 51,... Are switched from the neutral state shown in FIG.
Can be rotated in the direction opposite to the arrow X. In this manner, the steering control can be more positively performed, such as by automatically steering the steering system in the neutral state of the first and second clutch mechanisms 41,.

FIG. 14 is a graph showing the relationship between the motor torque and the auxiliary torque of the electric power steering apparatus according to the present invention. FIG. 14A shows Comparative Example 1 in which the motor system and the steering system are always connected, and FIG. Comparative Example 2 including a clutch that is released when the steering torque is equal to or less than a predetermined value, (c) shows an embodiment of the present invention, in which the horizontal axis represents the generated torque (motor torque) TM of the electric motor 5, and the vertical axis represents the This is the auxiliary torque TA added to the steering system. When the influence of the inertia, viscous resistance, and frictional resistance of the electric motor 5 and the torque transmitting means 6 is α,
TA = TM−α.

In (a), if the first and third quadrants of the graph are the steering direction right and left, in the region of TM ≧ 0, a straight line of a → b → c (TA = TM−α) is obtained. TM <
In the region of 0, the line becomes a point-symmetric line (d → e → f) with respect to the origin 0 of the line. When the steering wheel is switched from the right steering torque state to the left steering torque state, a →
Although TA changes in the order of b → c → d → e → f, TA in the range of b → c becomes negative and the steering wheel becomes heavy. d
→ The same applies to the range of e. The hatched area in the graph is where the steering frequency is highest, so it is not desirable that the steering wheel becomes heavy.

In (b), the relationship between T M and T A is a → b → e → f. That is, the component of α accompanying the inertia and friction of the electric motor 5 and the torque transmitting means 6 has been cut, and the steering wheel does not become heavy in the range of b → e. However, automatic steering control of the steering system cannot be performed in the neutral state of the clutch mechanism.

On the other hand, in (c), as described in detail with reference to FIGS. 9 and 10, the first and second clutch mechanisms 41, 51,... Become neutral when the steering torque is smaller than a predetermined value. When the steering torque becomes equal to or more than the predetermined value, one of the states shifts to the release state. First and second clutch mechanisms 41 ..., 51 ... are switched torque until transition to a state of releasing the one from the neutral state (steering torque) is an T ₁₀ as hereinbefore described with reference to FIG. 9 (a) the switching torque T ₁₀ is TA and the point c, less than TA point d. As a result, the relationship between TM and TA is a → b → b ₀ → c ₀ → d ₀ → e ₀
→ e → f. That is, the weight of the handle in the range of b → e is need only switching torque T ₁₀ minutes. For this reason, the steering wheel operating force can be extremely small in the range of b → e as compared with the above (a), and the steering wheel is light. In addition, since both the first and second clutch mechanisms 41, 51,... Are in the neutral state in which both are engaged, steering control can be more positively performed, such as automatic steering control of the steering system.

Next, another embodiment of the present invention will be described with reference to FIG.
21 will be described with reference to FIG. The same components as those in the above embodiment are denoted by the same reference numerals, and description thereof will be omitted. FIG. 15 is an overall configuration diagram of an electric power steering device (other embodiment) according to the present invention. An electric power steering device 71 includes a steering torque detecting unit that detects a steering torque of a steering system generated by a steering handle 2. 73, a control means 4 for generating a control signal based on the detection signal of the steering torque detection means 73, an electric motor 75 for generating an auxiliary torque corresponding to the steering torque based on the control signal of the control means 4, Mechanical clutch 40 for transmitting the assist torque of electric motor 75 to the steering system
And a torque transmission means 76 for steering wheels (steered wheels) 9, 9 via a pinion 7 and a rack 8a.

FIG. 16 is a sectional view showing a main part of an electric power steering apparatus (another embodiment) according to the present invention.
The left half of the input / output axis L is cut along the input / output axis L, and the right half of the input / output axis L is cut along the axis of the electric motor 75 on the near side of FIG. .
The steering system of the electric power steering device 71
A tubular input shaft 11 connected to the steering handle 2 (see FIG. 15), and a torsion bar 1 inserted through the input shaft 11 and having an upper portion connected to the input shaft 11 by a pin 12
3 and an output shaft 15 which is serrated to the lower portion of the torsion bar 13 and provided with the pinion 7 at the lower portion are main components.

FIG. 17 is an enlarged view of a main part of an electric power steering apparatus (another embodiment) according to the present invention. The steering torque detecting means 73 detects the steering torque of the steering system by detecting the relative torsion angle between the input / output shafts 11 and 15, and includes a slider 81 and a variable inductance sensor. The slider 81 is a cylindrical body having an inclined groove 81a and a vertically long straight groove 81b on a side wall, and is bridged between the input shaft 11 and the output shaft 15 so as to move in the axial direction according to a relative torsional displacement. It is displaced. The amount of displacement of the slider 81 in the axial direction is proportional to the torque. The sensor 82 converts the displacement of the slider 81 into an electric signal. In the figure, reference numeral 83 denotes a compression spring.

FIG. 18 is a sectional view taken along the line 18-18 in FIG. 17, and the electric motor 75 is provided by interposing torque transmitting means 76 between the mechanical clutch mechanism 40 and the steering system.
Is transmitted in the order of the mechanical clutch mechanism 40, the torque transmitting means 76, and the steering system. The electric motor 75 includes a case 84 bolted to the housing 26, a stator 85, a rotor 86, and an electric shaft (output shaft of the electric motor) 87.

The torque transmitting means 76 is a worm gear reduction mechanism comprising a worm 88 connected to the electric shaft 87 of the electric motor 75 and a wheel 89 connected to the output shaft 15. The wheel 89 has a boss 89 connected to the output shaft 15.
It is provided integrally with a. The worm 88 has a structure in which a worm shaft 88 a is integrally formed, and one end of the worm shaft 88 a is rotatably supported by a tip of the electric shaft 87. In the figure, 91 and 92 are bearings for electric shafts, 93
Denotes a worm shaft bearing.

Here, once returning to FIG.
The slider 81 has a circumferential groove 81c formed on the outer periphery of the lower end. The worm shaft 88a is rotatably fitted with a cylindrical position control means 94. The position control means 94 is provided in the inclined hole 9 through which a pin 88b provided on the worm shaft 88a passes.
4a and an outer peripheral groove 94b. The housing 26 supports a central support portion 95a of an L-shaped link 95 in a side view so as to be vertically rotatable. Circumferential groove 94 of position control means 94
b is a combination configuration. Therefore, the position control means 94 is connected to the steering handle 2 shown in FIG.

FIG. 19 is a cross-sectional view of the periphery of a mechanical clutch mechanism according to the present invention (another embodiment). Electric shaft 87
Has an input member 96 connected to the distal end thereof, and an end of the worm shaft 88a rotatably supported at the end penetrating the input member 96 and concentrically via a needle bearing 97. The input member 96 includes an electric shaft bearing 92.
And is rotatably supported by the housing 26 via the. The mechanical clutch 40 shown in FIG.
The worm shaft 8
8a and three position control members 64 provided in the position control means 94 are arranged inside the input member 96. The cross-sectional configuration of the mechanical clutch 40 will be described in detail with reference to FIG. Note that no torsion bar is interposed between the electric shaft 87 as the input shaft and the worm shaft 88a as the output shaft.

FIG. 20 is a sectional view taken along line 20-20 of FIG. 19, and shows a sectional structure of a mechanical clutch 40 (another embodiment) according to the present invention. The housing 26 is omitted. The mechanical clutch 40 according to another embodiment has the same configuration as the mechanical clutch 40 shown in FIGS. In this configuration, the worm shaft 88a functions as an output shaft of the mechanical clutch 40. Further, the mechanical clutch 40 has the function shown in FIGS. 8 to 14 and the description thereof is omitted.

FIG. 21 is an operation diagram of the slider and the position control section (another embodiment) according to the present invention. Slider 81
Is displaced in the axial direction (arrow direction) according to the relative torsional displacement between the input shaft 11 and the output shaft 15 shown in FIG. 17 based on the steering torque of the steering handle 2. Accordingly, the link 95 swings in the arrow direction because the pin portion 95b at one end is pulled up by the circumferential groove 81c. The position control means 94 moves in the direction of the arrow because the circumferential groove 94b is pressed by the pin 95c at the other end. In this case, the position control means 94 is displaced in the circumferential direction (the direction of the arrow) by the engagement between the pin 88b and the inclined groove 94a. Accordingly, the mechanical clutch 40 performs the engaging action and the releasing action shown in FIGS.

In another embodiment, the mechanical clutch 40
Torque transmission means (reduction mechanism) between the motor and the steering system
Since the auxiliary torque of the electric motor 75 is transmitted in the order of the mechanical clutch 40, the torque transmission means 76, and the steering system by interposing the motor 76, FIGS.
As compared with the configuration shown in FIG. 7, the auxiliary torque transmitted to the mechanical clutch 40 can be an extremely small torque inversely proportional to the reduction ratio of the torque transmitting means 76. Since the auxiliary torque is small, the transmission capacity of the clutch can be reduced, and as a result,
The mechanical clutch 40 can be reduced in size and weight.

In the above-described embodiment and other embodiments, the elastic member 13 can generate a relative torsional displacement between the input shaft 11 and the output shaft 15 in proportion to the steering torque. Well, it is not limited to torsion bars. The number of the first and second clutch mechanisms 41, 51,... Is not limited to three sets, but can be set arbitrarily.

The output member 34 may be mounted so as to be movable in the radial direction relative to the input member 32b.
In addition to allowing the output member 34 to move in the radial direction, a configuration in which the input member 32b can move in the radial direction may be employed.
The tapered space portion 61 only needs to be partially expanded so that the engagement member 62 can be separated from the frictional engagement surface when not engaged. For example, a concave portion is formed on the inner peripheral surface of the input member 32b. May be provided.

The output member 34 may be moved in the radial direction by being pressed by the other engaging members 62 when some of the engaging members 62 are disengaged, regardless of the moving direction. If the output member 34 is moved by pressing with the other engaging members 62.
This is because the frictional engagement force between these other engagement members 62 and the output member 34 can be reduced. Output member 34
The member for guiding the movement in the radial direction is not limited to the pin 14. The elastic member that presses the output member 34 against the output shaft 15 is not limited to the compression spring 35 but may be, for example, a disc spring.

The tapered space portion 61 may be formed between the inner peripheral surface of the input member 32b and the outer peripheral surface of the output member 34, and may have the shape of the outer peripheral surface (friction engagement surface) of the output member 34. Also, the present invention is not limited to those shown in FIGS. Then, the inner peripheral surface of the input member 32b is formed into a predetermined polygon, and the output member 3
The outer peripheral surface of 4 may be circular. The engaging member 62 may be any member that can switch between engagement and non-engagement with the circumferential end of the tapered space portion 61, and may be, for example, spherical, in addition to column. The biasing member of the mechanical clutch 40 is a compression spring 65
However, the present invention is not limited to this, and may be made of, for example, a hard rubber material or a leaf spring.

Further, the first and second clutch mechanisms 41.
.. May have the configuration of a friction engagement type clutch, for example, a well-known sprag type clutch. The sprag type clutch is configured such that an outer member (corresponding to the input member 32b) having a cylindrical inner peripheral engaging surface and an inner member (corresponding to the output member 34) having a cylindrical outer peripheral engaging surface are concentric. The two engagement surfaces are opposed to each other, and a plurality of sprags (wedges) are provided in a gap therebetween, and a member (position control member) connected to a steering handle for positioning these sprags. 64) and a spring for urging the sprags toward the two engagement surfaces so as to wedge-engage them (such as a clutch device disclosed in JP-A-1-188727).

[0085]

According to the present invention, the following effects are exhibited by the above configuration. In order to achieve the above object, the invention according to claim 1 generates an auxiliary torque according to a steering torque by an electric motor,
An input member for transmitting the auxiliary torque to the steering system via a frictional engagement type bidirectional clutch mechanism, wherein the input member connects the frictional engagement type bidirectional clutch mechanism to an electric motor;
An output member arranged coaxially with the input member and connected to a steering system; a tapered space formed between an inner peripheral surface of the input member and an outer peripheral surface of the output member; It comprises an interposed engaging member, an urging member for urging the engaging member in the taper direction of the tapered space portion, and a position control member connected to the steering handle for positioning the engaging member. An input / output member is switched to an engaged / unengaged state by an engaging member which engages or disengages with the frictional engagement surface of the tapered space portion by wedge action with the rotation of the position control member. In the electric power steering device of the type, the position control member of the frictional engagement type bidirectional clutch mechanism is arranged at a position away from the engagement member in the neutral state of the clutch so that the input / output member in the neutral state is engaged. Structure And said that the content was.

In the neutral state of the clutch, the position control member is at a position away from the engagement member. All engagement members are
The input / output member is engaged by being pushed by the urging member and engaging with the frictional engagement surface of the tapered space. From such a neutral state, the steering torque for releasing the frictional engagement type bidirectional clutch mechanism by turning the output member with the steering handle is small enough to disengage the engagement member. At this time, since the electric motor is stopped and the friction engagement type bidirectional clutch mechanism is engaged, the steering handle receives a reaction force due to the inertia and frictional resistance of the electric motor. However, the maximum value of the effect does not exceed the steering torque for releasing the clutch. Therefore, the influence of the inertia and frictional resistance of the electric motor is extremely small as compared with the direct electric motor system without the clutch. As a result, a good steering feeling (steering feeling) can be obtained in a region where the steering force of the steering wheel is small. Further, even when the frictional engagement type bidirectional clutch mechanism is in a neutral state, the drive torque (auxiliary torque) of the electric motor can be transmitted to the steering system. Therefore, the steering control can be more positively performed, such as by automatically controlling the steering system in the neutral state of the clutch.

According to a second aspect of the present invention, a speed reduction mechanism is interposed between the frictional engagement type bidirectional clutch mechanism and the steering system so that the auxiliary torque of the electric motor can be reduced by the frictional engagement type bidirectional clutch mechanism, the reduction mechanism, and the steering. It is characterized in that it is transmitted in the order of the system.

As compared with the case where the frictional engagement type bidirectional clutch mechanism is connected after the speed reduction mechanism, the auxiliary torque transmitted to the frictional engagement type bidirectional clutch mechanism requires an extremely small torque inversely proportional to the reduction ratio of the reduction mechanism. Since the auxiliary torque is small, the transmission capacity of the clutch can be reduced, and as a result, the friction engagement type bidirectional clutch mechanism can be reduced in size and weight.

According to a third aspect of the present invention, the frictional engagement type bidirectional clutch mechanism is a plurality of sets arranged on the same circle, and at least one of the plurality of sets of the frictional engagement type bidirectional clutch mechanism is replaced with another. An early release clutch that is disengaged at a timing earlier than the clutch mechanism of (1).

If only one set of clutch mechanisms is released at an early timing, the other clutch mechanisms lose their balance and exert a resultant force in the direction of release, so that the frictional force is reduced and released with a small release force. Therefore, the clutch mechanism can be reliably released with a smaller release force than when all the clutch mechanisms are released at once.

The invention according to claim 4 is characterized in that an output shaft is provided in the steering system, and the output member is mounted on the output shaft so as to be movable in the radial direction.

Since the output member is mounted on the output shaft so as to be movable in the radial direction, when a part of the plurality of engagement members engaged with the output member comes off, the balance of the force for pushing the output member by the engagement member is reduced. Crumble. When the balance is lost, the output member is pushed by one of the other engagement members and moves in the radial direction. As a result, the frictional force between the output member and the other engagement member is reduced, and the engagement is released more stably. In this way, when some of the clutch mechanisms are released, the other clutch mechanisms are released more stably, so that even when the electric motor rotates for some reason, all the clutch mechanisms are released at once. The release can be reliably performed with a release force smaller than the release.

The invention according to claim 5 is characterized in that the output member is provided with an elastic member for pressing the output member against the output shaft, so that a preload in the movement direction is applied to the output member with respect to the output shaft.

After all clutch mechanisms are released, the output member that has moved in the radial direction can be automatically returned to the original neutral position by the elastic force of the elastic member. For this reason, the clutch mechanism can be disengaged with a small disengaging force as many times as possible, and the clutch function can be stabilized.
Productivity increases.

According to the present invention, even when the position of the engaging member in the tapered space portion changes with the radial movement of the output member, the wedge angle at the contact portion of the engaging member is substantially constant. The taper angle correcting portion is formed on the frictional engagement surface so as to be as follows.

Even if the output member is eccentric with respect to the input member for some reason, and the position of the engaging member in the tapered space portion is changed due to the eccentricity, the taper angle correcting portion is not in contact with the frictional engagement surface. Correction is made so that the wedge angle with the engaging member is substantially constant. As a result, even if the position of the engaging member in the tapered space changes with the eccentricity of the output member, the wedge angle is substantially constant, and the wedge action does not change. Therefore, the release force for releasing the engagement member from the tapered space does not increase, and the proper release force can be always maintained.

The invention according to claim 7 is characterized in that a part of the tapered space portion is expanded so that the engaging member can be separated from the frictional engagement surface when not engaged.

Since a part of the tapered space is expanded, the gap between the expanded part and the engagement member when not engaged is large. For this reason, since the engagement member at the time of non-engagement can be reliably separated from the friction engagement surface, the amount of radial movement of the output member can be increased, and as a result, the clutch mechanism is reliably released. be able to.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an electric power steering device according to the present invention.

FIG. 2 is a configuration diagram of a control unit according to the present invention.

FIG. 3 is an enlarged sectional view of a main part of the electric power steering device according to the present invention.

FIG. 4 is a sectional view taken along line 4-4 in FIG. 3;

FIG. 5 is an exploded perspective view of a main part of the electric power steering device according to the present invention.

FIG. 6 is a sectional view taken along line 6-6 in FIG. 3;

FIG. 7 is a detailed view of part 7 of FIG. 6;

FIG. 8 is an operation diagram of a taper angle correction unit according to the present invention.

FIG. 9 is a switching principle diagram of a mechanical clutch.

FIG. 10 is an operation diagram of a mechanical clutch according to the present invention.

FIG. 11 is an operation diagram of the mechanical clutch according to the present invention.

FIG. 12 is an operation diagram of a mechanical clutch according to the present invention.

FIG. 13 is an operation diagram of the mechanical clutch according to the present invention.

FIG. 14 is a graph showing a relationship between an electric motor torque and an auxiliary torque of the electric power steering device according to the present invention.

FIG. 15 is an overall configuration diagram of an electric power steering device (another embodiment) according to the present invention.

FIG. 16 is a cross-sectional configuration diagram of a main part of an electric power steering device (another embodiment) according to the present invention.

FIG. 17 is an enlarged view of a main part of an electric power steering device (another embodiment) according to the present invention.

18 is a sectional view taken along line 18-18 of FIG. 17;

FIG. 19 is a cross-sectional view around a mechanical clutch mechanism (another embodiment) according to the present invention.

20 is a sectional view taken along line 20-20 in FIG. 19;

FIG. 21 is an operation diagram of a slider and a position control unit (another embodiment) according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electric power steering device, 2 ... Steering handle, 5,75 ... Electric motor, 6,76 ... Torque transmission means as a reduction mechanism, 9 ... Steering wheel (wheel), 11 ... Input shaft, 13 ... Torsion bar, 15 ... Output shaft, 32b, 9
6: input member, 32c: inner peripheral surface of input member (input side frictional engagement surface), 34: output member, 34a: through hole, 34b
... engagement surface of output member (friction engagement surface on output side), 34c ...
Recessed recess, 34d: taper angle correction unit, 35: elastic member (compression spring), 40: mechanical clutch, 41, 41A ...
Friction engagement type clutch (first clutch mechanism), 51, 51
A: friction engagement type clutch (second clutch mechanism), 61 ...
Tapered space, 62, 62A ... engaging member, 64, 64
A: position control member, 65: urging member (compression spring), 87
... an electric shaft as an input shaft, 88a ... a worm shaft as an output shaft.

Claims (7)

[Claims] An electric motor generates an auxiliary torque according to a steering torque, and transmits the auxiliary torque to a steering system via a friction engagement type bidirectional clutch mechanism, wherein the friction engagement type bidirectional clutch mechanism is provided. An input member connected to the motor, an output member arranged coaxially with the input member and connected to the steering system, and a tapered shape formed between the inner peripheral surface of the input member and the outer peripheral surface of the output member. A space portion, an engagement member interposed in the tapered space portion, an urging member for urging the engagement member in a taper direction of the tapered space portion, and a positioning member for positioning the engagement member. Consists of a position control member connected to the steering handle,
The input / output member is brought into the engaged / unengaged state by the engaging member engaged or disengaged by the wedge action on the frictional engagement surface of the tapered space portion with the rotation of the position control member. In a switching type electric power steering device, a position control member of the friction engagement type bidirectional clutch mechanism is
The electric power steering apparatus according to claim 1, wherein in a neutral state of the clutch, the input / output member in the neutral state is engaged by disposing the clutch at a position away from the engaging member. 2. By interposing a speed reduction mechanism between the friction engagement type bidirectional clutch mechanism and a steering system,
2. The electric power steering apparatus according to claim 1, wherein the auxiliary torque of the electric motor is transmitted in the order of a friction engagement type bidirectional clutch mechanism, a speed reduction mechanism, and a steering system. 3. The friction engagement type bidirectional clutch mechanism has a plurality of sets arranged on the same circle, and at least one of the plurality of sets of friction engagement type bidirectional clutch mechanisms is more than other clutch mechanisms. 3. The electric power steering apparatus according to claim 1, wherein the clutch is an early release clutch which is disengaged at an early timing. 4. The electric power steering apparatus according to claim 3, wherein an output shaft is provided in the steering system, and the output member is mounted on the output shaft so as to be movable in a radial direction. 5. The pre-load according to claim 4, wherein an elastic member is provided for pressing the output member against the output shaft, so that a preload is applied to the output member in the movement direction. Electric power steering device. 6. A wedge angle at a contact portion of the engagement member is substantially constant even when a position of the engagement member in the tapered space changes with a radial movement of the output member. The electric power steering device according to claim 4 or 5, wherein a taper angle correction unit is formed on the friction engagement surface. 7. The device according to claim 4, wherein a part of said tapered space portion is expanded so that said engagement member can be separated from said friction engagement surface when not engaged. The electric power steering device according to claim 6.