JP3666764B2 - Electric power steering device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to an improvement in an electric power steering apparatus.
[0002]
[Prior art]
  In recent years, electric power steering devices have been frequently used in order to reduce the steering force of the steering wheel to give a comfortable steering feeling. This type of electric power steering apparatus generates an auxiliary torque corresponding to the steering torque by an electric motor, and transmits this auxiliary torque to a steering system via a mechanical clutch. For example, Japanese Patent Application Laid-Open No. 64-69829. There is a technology of “clutch device”.
  According to FIGS. 1 to 3 of this publication, this technique includes a cylindrical external member 21 connected to a motor 15 (the numbers are those cited in the publication; the same applies hereinafter) and a steered wheel. The shaft portion 32 with the inner member 22 connected to is connected via the clutch device 20.
[0003]
  The clutch device 20 is composed of a plurality of sets of friction engagement clutch mechanisms arranged on the same circle, and these clutch mechanisms are a pair formed between the inner surface of the outer member 21 and the outer surface of the inner member 22. A wedge-shaped space 28, 28 '(corresponding to a tapered space), a pair of rolling elements 24, 24' interposed in the wedge-shaped space 28, 28 ', and a spring 25 interposed between the rolling elements 24, 24'; It comprises a cage 23 for positioning the rolling elements 24, 24 '.
  The rolling elements 24, 24 ′ selectively switch the outer member 21 and the inner member 22 to engagement / disengagement (engage / release clutch) as the retainer 23 moves.
[0004]
[Problems to be solved by the invention]
  Generally, at the time when reverse steering of the steering wheel 11 is started (for example, when changing from the right steering state to the left steering state), the motor 15 is stopped because the steering torque is minute, and the auxiliary torque is transmitted to the clutch device 20. Not. For this reason, in order to release the clutch device 20, it is necessary to apply a release force larger than the friction force for engaging the rolling elements 24 or 24 '. However, in order for the driver to obtain a comfortable steering feeling, the release force is preferably as small as possible.
  On the other hand, the clutch device 20 of the electric power steering device is required to be able to be surely released even when the auxiliary torque from the motor 15 is transmitted for some reason. In this case, there is an inconvenience that a larger release force than usual is required, and the burden on the driver is increased.
[0005]
  Therefore, the object of the present invention is the following (1) and (2).
(1) To provide an electric power steering device provided with a friction engagement clutch mechanism having a small release force.
(2) To provide an electric power steering apparatus provided with a friction engagement clutch mechanism that can be released more reliably.
[0006]
[Means for Solving the Problems]
  In order to achieve the above-mentioned object, the invention according to claim 1 connects an input member connected to an electric motor and an output shaft with an output member connected to a steering wheel via a plurality of sets of friction engagement clutch mechanisms. An engagement member interposed between the input / output members to engage the input / output members; a position control member coupled to a steering handle for positioning the engagement members; And a biasing member that biases the engagement member toward the position control member, and the input / output member is switched to engagement / disengagement by the engagement member as the position control member rotates. In the electric power steering device that transmits the auxiliary torque from the electric motor to the output shaft,
  The output member and the output shaft are configured as separate members, and the output member is attached to the output shaft so as to be movable in the radial direction.,
  Position control members of the plurality of sets of clutch mechanisms are arranged on the same circle while being separated from each other, and one set of the plurality of sets of clutch mechanisms is disengaged at an earlier timing than the other clutch mechanisms. In order to achieve this, the arc length of the position control member of the one set of clutch mechanisms is set larger than the other position control members,
  Provided with an elastic member for pressing the output member against the output shaftIt is characterized by that.
[0007]
  Since the output member having a complicated shape for engaging the engaging member between the input and output members is constituted by a member separate from the output shaft, the output member can be easily manufactured and the productivity is high.
  Further, 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 engaging members engaged with the output member is removed, the balance of the force pressing the output member with the engaging member is balanced. Collapse. For this reason, the output member is pressed in one direction by the other engaging member and moves in the radial direction. As a result, the frictional force between the output member and the other engaging member decreases, and the engagement is released. Thus, when a part of the clutch mechanisms is released, the other clutch mechanisms are also released with a reduced frictional force. Therefore, it can be reliably released with a smaller release force than releasing all the clutch mechanisms at once.
[0008]
  Moreover,With a simple configuration in which the arc length of the position control member of one set of clutch mechanisms is simply increased, only one set of clutch mechanisms can be easily released at an early timing. As a result, when one set of clutch mechanisms is released, the other clutch mechanisms are also released with a reduced frictional force. Therefore, it can be reliably released with a smaller release force than releasing all the clutch mechanisms at once.
[0009]
  Further, the output member moved in the radial direction can be automatically returned to the original neutral position with respect to the output shaft by the elastic force of the elastic member after all the clutch mechanisms are released. this Therefore, the output member can be automatically and repeatedly moved in the radial direction, and therefore the clutch mechanism can be reliably released with a small releasing force any number of times.
[0010]
  According to a second aspect of the present invention, when only the one set of clutch mechanisms is disengaged, the output engaged with the engaging member of the other clutch mechanism so as to freely move the output member in the radial direction. The engaging surface of the member is made to have a draft angle.
When one set is released, the output member can move in the radial direction without any restriction. For this reason, it is possible to release the other clutch mechanisms more reliably by simply releasing one set of clutch mechanisms.
[0011]
  Claim3The described invention is characterized in that the elastic direction of the elastic member is matched with the moving direction of the output member.
  Due to the elastic force of the elastic member, the output member can be held at the original neutral position with respect to the output shaft, so that the output member does not rattle in the moving direction. As a result, although the output member and the output shaft are separated from each other, no rattling noise or the like is generated and the quality can be improved.
[0012]
  Claim4The described invention is characterized in that the output member is held on the output shaft by an elastic member having a damping function such as rubber.
  The operating sound (sounding sound) generated in the clutch mechanism can be attenuated by the elastic member. For this reason, since the operating sound is difficult to be transmitted to the vehicle interior, the noise prevention effect is high, and the commercial value of the electric power steering device is increased.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
  Embodiments of the present invention will be described below with reference to the accompanying drawings. The drawings are viewed in the direction of the reference numerals.
  FIG. 1 is an overall configuration diagram of an electric power steering apparatus according to the present invention. The electric power steering apparatus 1 includes a steering torque detecting means 3 for detecting a steering torque of a steering system generated by a steering handle 2, and the steering torque detection. A control means 4 that generates a control signal based on the detection signal of the means 3, an electric motor 5 that generates an auxiliary torque according to the steering torque based on the control signal of the control means 4, and steering the auxiliary torque of the electric motor 5 It consists of a torque transmission means 6 for transmitting to the system and a mechanical clutch 40, and steers wheels (steering wheels) 9, 9 via a pinion 7 and a rack 8a.
[0014]
  FIG. 2 is an enlarged cross-sectional view of a main part of the electric power steering apparatus according to the present invention. A tubular input shaft 11 connected to the steering handle 2 (see FIG. 1), and an input shaft that is inserted into the input shaft 11 and is input. 11 is composed of a torsion bar (elastic member) 13 whose upper part is coupled with a pin 12 and an output shaft 15 which is coupled to the lower part of the torsion bar 13 with a pin 14 and engraved with the pinion 7 below. It is a thing.
  The torsion bar 13 is a member that literally generates a torsion angle accurately with respect to torque, and generates a relative torsional displacement between the input shaft 11 and the output shaft 15. The rack 8a is engraved on the rack shaft 8 extending in the front and back direction in this figure. The input shaft 11, the torsion bar 13, and the output shaft 15 are concentric.
[0015]
  The steering torque detecting means 3 detects the steering torque of the steering system by detecting the relative torsion angle between the input / output shafts 11 and 15, and in this embodiment, a potentiometer is used. The steering torque detecting means (potentiometer) 3 includes a detection main body 21 including a resistance element (not shown) and a sliding contact that moves along the resistance element, and a rotation for operating the sliding contact in the detection main body 21. It consists of a rod-shaped actuator 22 that moves.
  The steering torque detecting means 3 attaches the detection main body 21 to the lower outer peripheral surface of the input shaft 11 with a bolt, and attaches the tip end of the actuator 22 to the engagement groove 15 a provided on the upper outer peripheral surface of the output shaft 15. By engaging, the relative torsion angle between the input and output shafts 11 and 15 is detected.
[0016]
  The steering torque detecting means 3 includes a torsion spring 23 for urging the actuator 22 toward one side wall of the engagement groove 15a. For this reason, the actuator 22 has no play in the rotating direction.
  The input shaft 11 includes an electric cable 25 that is wound a plurality of times (for example, about 3 turns) around the cable reel 24, one end of the electric cable 25 is connected to the detection main body 21 of the steering torque detecting means 3, and the other end is a housing. It is connected to the connector 27 on the 26th side.
[0017]
  A 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 connected to the cylindrical member. It is formed in order from the bottom in the direction.
  The mechanical clutch 40 is disposed inside the input member 32b, and its cross-sectional configuration will be described in detail with reference to FIG.
  In the figure, 36, 37 and 38 are bearings, and 39 is a dust cover.
[0018]
  3 is a cross-sectional view taken along line 3-3 in FIG. 2, and shows a cross-sectional structure of the torque transmitting means 6. As shown in FIG.
  The torque transmission means 6 is a worm gear mechanism including a worm 31 coupled to the output shaft 5a of the electric motor 5 and a wheel 32 rotatably supported on the output shaft 15. The electric motor 5 is bolted to the housing 26.
  Accordingly, in FIG. 2, the rack 8 is driven via the pinion 7 with a 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).
[0019]
  FIG. 4 is an exploded perspective view of a main part of the electric power steering apparatus according to the present invention.
  An annular position control means 63 with a tripod, which is a component of the mechanical clutch 40, is serrated to the lower end of the input shaft 11, and three position control members 64 (... are a plurality of parts) below the position control means 63. The same shall apply hereinafter). Therefore, the position control members 64 are connected to the steering handle 2 shown in FIG.
  On the other hand, the output shaft 15 includes an output member 34 at the upper end of the base.
[0020]
  FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 2, and shows a cross-sectional configuration of the mechanical clutch 40 according to the present invention. The housing 26 is omitted.
  The mechanical clutch 40 transmits the auxiliary torque of the electric motor 5 to the steering system only when the direction of operation of the auxiliary torque of the electric motor 5 coincides with the steering direction of the steering system (one-way clutch assembly). The assembly of a plurality of sets of friction engagement clutch mechanisms.
  These friction engagement clutch mechanisms include three sets of first clutch mechanisms 41... That engage in the arrow X direction (counterclockwise direction in the drawing) of the input member 32b, and three sets that engage in the reverse direction of the arrow X. The second clutch mechanism 51. The first clutch mechanisms 41 and the second clutch mechanisms 51 are alternately arranged on the same circle.
[0021]
  Specifically, the first and second clutch mechanisms 41... 51 are input via the tapered space portions 61 formed between the input / output members 32 b and 34 and the tapered space portions 61. A cylindrical engagement member 62 that engages the member 32 b and the output member 34, a position control member 64 that positions the engagement member 62, and the position control member 64. It comprises compression springs 65 as urging members for urging the combined members 62.
[0022]
  The output member 34 generally has a rice ball-shaped cross-sectional shape (a shape in which three sides of an isosceles triangular cross-section with corners cut off are arc-shaped).
  The tapered space portion 61 is a space portion formed between the circular inner peripheral surface of the input member 32b and the engagement surface (polygonal outer peripheral surface) of the output member 34 and having a tapered end in the circumferential direction. . The position control members 64... Are members that are rotatably arranged at an equal pitch on the same circle between the input member 32 b and the output member 34 while being separated from each other.
  The mechanical clutch 40 having such a configuration selectively switches the input member 32b and the output member 34 between engagement and disengagement as the position control members 64.
[0023]
  Of the first and second clutch mechanisms 41... 51..., One specific set (hereinafter referred to as “specific first and second clutch mechanisms 41A and 51A”) is earlier than the other sets. It becomes a non-engagement state at timing.
  Specifically, the arc length L of the position control member 64 (hereinafter referred to as “specific position control member 64A”) that positions the engaging members 62 of the specific first and second clutch mechanisms 41A, 51A.₁Is the arc length L of the other position control member 64.₂Bigger than. In the output member 34 having a substantially isosceles triangle cross section, the specific position control member 64A is disposed at one corner, and the other position control members 64 are disposed at two corners having the same angle. .
[0024]
  Further, the output member 34 is attached to the output shaft 15 so as to be movable in the radial direction.
  Specifically, an elliptical or elliptical through hole 34a is formed in the output member 34, the circular output shaft 15 is fitted into the through hole 34a, and the pin 14 is passed over the longitudinal axis of the through hole 34a. The pin 14 is provided with an elastic member (compression spring or the like) 35, and the elastic member 35 is configured to press the through hole 34 a of the output member 34 against the output shaft 15.
  That is, an elastic member 35 is interposed between the outer peripheral surface of the output shaft 15 and the surface in the longitudinal axis direction of the through hole 34a, and the elastic direction of the elastic member 35 is determined by the moving direction of the output member 34 (the longitudinal axis of the through hole 34a). The output member 34 is pressed against the output shaft 15.
  The output member 34 is relatively pressed toward the center of the width of the specific position control member 64A.
[0025]
  When only one set of clutch mechanisms (specific first clutch mechanism 41A or specific second clutch mechanism 51A) is released, the other clutch mechanisms 41, 51, ... are engaged so that the output member 34 can be moved in the radial direction. The engaging surface of the output member 34 that engages with the members 62. Therefore, when one set is released, the output member 34 can move in the radial direction without any restriction. For this reason, it is possible to reliably release the other clutch mechanisms only by releasing one set of clutch mechanisms.
[0026]
  Next, the operation of the mechanical clutch 40 having the above configuration will be described with reference to FIGS. 1 and 6 to 9.
  6 to 9 are operation diagrams of the mechanical clutch according to the present invention.
  In FIG. 1, when the steering handle 2 is not steered, the control device 4 does not output an assist command signal because there is no signal from the steering torque detecting means 3. Therefore, the electric motor 5 is in a state in which no auxiliary torque is generated, and the first and second clutch mechanisms 41, 51,... Are all in a released state (neutral state) as shown in FIG.
[0027]
  Next, when the steering torque of the steering handle 2 is small and the electric motor 5 does not generate auxiliary torque, the phase between the position control member 64... Connected to the input shaft 11 (see FIG. 2) and the output member 34 is almost the same. It does not change. In this case, the position control members 64... Move slightly in the counterclockwise direction of the figure, for example, but the first clutch mechanisms 41. For this reason, the output member 34 is not affected by the friction or inertia of the electric motor 5, and rotates with the steering torque of the steering system (input shaft 11 → torsion bar 13 → output shaft 15) shown in FIG. To drive.
[0028]
  On the other hand, when the steering torque of the steering wheel 2 is large and the electric motor 5 generates auxiliary torque, the position control member 64 (including the specific position control member 64A) connected to the input shaft 11 and the output member 34 The phase of changes significantly. For example, as shown in FIG. 7, when the position control members 64 are largely moved in the direction of the arrow X, the engagement members 62 of all the first clutch mechanisms 41 are tapered by the urging force of the urging members 65. It moves to the circumferential direction edge part of space part 61 ..., and the input / output members 32b and 34 are switched to an engagement state with a frictional force. As a result, all the first clutch mechanisms 41 are engaged.
  As the electric motor 5 rotates, the input member 32b rotates in the direction of the arrow X, via the first clutch mechanism 41.Output member 34Auxiliary torque is transmitted to. For this reason, the output member 34 rotates in the direction of arrow X with the combined torque obtained by adding the auxiliary torque generated by the electric motor 5 to the steering torque of the steering system (input shaft 11 → torsion bar 13 → output shaft 15). 15 is driven.
[0029]
  Thereafter, when 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 steered in the reverse direction, as shown in FIG. 8, all the position control members 64... Rotate in the direction opposite to the rotation direction of the input member 32b (arrow Y direction). The specific position control member 64A comes into contact with the right adjacent engagement member 62 (referred to as “engagement member 62A” for convenience) prior to the other position control members 64. Extrude against the forces.
[0030]
  For this reason, the engaging member 62A releases the engagement of the specific first clutch mechanism 41A.
  At this time, the other position control members 64 are not in contact with the engagement members 62. Therefore, the other engagement members 62... Continue to the output member 34 and the arrow Z in the figure.₁, Z₂The vector indicated by 作用 acts, and based on the resultant force of these vectors, the output member 34 has an arrow Z in the figure.₃The eccentric load shown by acts. As a result, the output member 34 resists the resilience of the elastic member 35 and moves slightly toward the specific position control member 64A with the pin 14 as a guide. Accordingly, the engagement force of the other engagement members 62 is weakened.
[0031]
  Immediately thereafter, the other position control members 64 are also brought into contact with the engaging members 62 to return to the original neutral position as shown in FIG. As a result, the other first clutch mechanisms 41 are also released. The output member 34 automatically returns to the neutral position by the elastic force of the elastic member 35.
  In this case, since no frictional force is generated in the engaging members 62, the releasing force pressed by the other position control members 64 is small enough to resist the urging force of the urging members 65.
  Thus, in order to release the engagement of the three sets of the first clutch mechanisms 41, despite the rotation of the input member 32b, only a small release force for a maximum of one set is required, It can be released reliably.
[0032]
  The second clutch mechanisms 51 are reversely operated to the first clutch mechanisms 41, and when the steering handle 2 is steered in the reverse direction, the operation described with reference to FIGS. It can be switched to engagement / disengagement by the same operation.
[0033]
  Next, another embodiment of the present invention will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected about the same structure as the said embodiment, and the description is abbreviate | omitted.
  FIG. 10 is a sectional view of a mechanical clutch (another embodiment) according to the present invention, and shows a modification of the mechanical clutch 40 shown in FIG.
  The mechanical clutch 40 according to another embodiment is provided with a shaft piece 15b having elasticity in the output shaft 15 by forming a slit S extending in the axial direction at the tip of the output shaft 15, and this shaft piece 15 b serves as the elastic member 35. The shaft piece portion 15 b is interposed so as to press the output member 34 against the output shaft 15, and the elastic direction is made to coincide with the moving direction of the output member 34.
[0034]
  FIG. 11 is a cross-sectional view taken along line 11-11 of FIG. 10, and the output member 34 has a generally rice-shaped cross-sectional shape (a shape in which three sides of a regular triangular cross-section with corners cut off are arc-shaped).
  In another embodiment, both end portions of the distal end portion of the output shaft 15 are chamfered to form a straight portion 15 c, while an elongated hole for fitting the through hole 34 a of the output member 34 to the straight portion 15 c of the output shaft 15. It is characterized by that. The straight portion 15 c has a role of guiding the radial movement of the output member 34.
[0035]
  Further, the position control members 64 are arranged at the same pitch on the same circle, but the claws on the specific clutch mechanisms 41A, 51A side are longer than the claws on the other clutch mechanisms 41, 51 ... (L₃> L₄).
  Specifically, the position control members 64...₁~ O₃Is matched with each corner of the output member 34 having a substantially equilateral triangle cross section. The two position control members 64 (specific position control members 64A and 64A) are₁, O₂Arc length L of the parts facing each other (referred to as "long nails")₃Is the arc length L of the other part (referred to as “short claw”).₄Bigger than. The long claws position the engaging members 62 of the specific first and second clutch mechanisms 41A and 51A. The other one position control member 64 has a center O₃L is the same for both left and right arcs₄, L₄It is the same as the arc length of the short claw.
[0036]
  The output member 34 is movable toward an intermediate position between the specific first clutch mechanism 41A and the specific second clutch mechanism 51A (intermediate position between the specific position control members 64A and 64A). The direction of the through hole 34a matches the moving direction of the output member 34..
  The torsion bar 13 is coupled to the output shaft 15 by serration or the like.
  According to such other embodiment, the pin 14 and the elastic member 35 which consist of another member are unnecessary, there are few parts, and the assembly | attachment of an electric power steering device is easy.
[0037]
  Next, the operation of the mechanical clutch 40 of the other embodiment will be described with reference to FIGS. 1 and 12 to 15.
  12 to 15 are operation diagrams of a mechanical clutch (another embodiment) according to the present invention.
  When the steering handle 2 is not steered, the first and second clutch mechanisms 41, 51,... Are all in a released state (neutral state) as shown in FIG.
[0038]
  Next, when the steering torque of the steering wheel 2 is small and the electric motor 5 does not generate auxiliary torque, the phase between the position control members 64 and the output member 34 hardly changes, so that the first clutch mechanism 41 is engaged. It does n’t come together. For this reason, the output member 34 is not affected by the friction or inertia of the electric motor 5, and FIG.And FIG.Steering system shown in(Input shaft 11 → torsion bar 13 → output shaft 15)And the output shaft 15 is driven.
[0039]
  On the other hand, when the steering torque of the steering wheel 2 is large and the electric motor 5 generates the auxiliary torque, the phase between the position control members 64... For example, as shown in FIG. 13, the position control members 64... Move greatly in the direction of the arrow X, so that all the first clutch mechanisms 41. For this reason, the output member 34 rotates in the direction of arrow X with a composite torque obtained by adding the auxiliary torque generated by the electric motor 5 to the steering torque of the steering system, and drives the output shaft 15.
[0040]
  Thereafter, when the auxiliary torque is continuously transmitted by the electric motor 5 for some reason, when the steering handle 2 is steered in the reverse direction, as shown in FIG. 14, all the position control members 64. Turn in the direction opposite the rotation direction (arrow Y direction). AndIn the specific first clutch mechanism 41AThe specific position control member 64A abuts on and engages with the engagement member 62A prior to the other position control members 64. For this reason, the engaging member 62A releases the engagement of the specific first clutch mechanism 41A.
[0041]
  At this time, the other position control members 64 are not in contact with the engagement members 62. Therefore, the other engagement members 62... Continue to the output member 34 and the arrow Z in the figure.₁, Z₂The vector indicated by 作用 acts, and based on the resultant force of these vectors, the output member 34 has an arrow Z in the figure.₃The eccentric load shown by acts. As a result, the output member 34 resists the resilience of the shaft piece 15b and moves slightly with the straight portion 15c as a guide. Accordingly, the engagement force of the other engagement members 62 is weakened.
  Immediately thereafter, the other position control members 64... Press the engagement members 62..., And the other first clutch mechanisms 41. The output member 34 automatically returns to the neutral position by the elastic force of the shaft piece 15b.
[0042]
  Thus, in order to release the engagement of the three sets of the first clutch mechanisms 41, despite the rotation of the input member 32b being continued,Release force that releases only one set of the specific first clutch mechanism 41A, that is,A small release force for one set is sufficient, and it can be released reliably.
  The second clutch mechanisms 51 are reversely operated to the first clutch mechanisms 41, and when the steering handle 2 is steered in the reverse direction, the operation described with reference to FIGS. It can be switched to engagement / disengagement by the same operation.
[0043]
  Next, still another embodiment of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected about the same structure as said other embodiment, and the description is abbreviate | omitted.
  FIG. 16 is a cross-sectional view of a mechanical clutch (another embodiment) according to the present invention, and shows a modification of the mechanical clutch 40 of the other embodiment shown in FIG.
  The mechanical clutch 40 of still another embodiment is characterized in that the output member 34 is held on the output shaft 15 by an elastic member 71 having a damping function such as rubber.
[0044]
  Specifically, the elastic member 71 is interposed between the straight portion 15 c of the output shaft 15 and the through hole 34 a of the output member 34. Further, the elastic member 71 includes an elastic pressing portion 71a having a cavity so as to play the same role as the compression spring 35 of FIG. 5 and the shaft piece portion 15b of FIG. That is, the elastic pressing portion 71 a is interposed so as to press the output member 34 against the output shaft 15, and the elastic direction matches the moving direction of the output member 34.
  According to such further another embodiment, the operating sound (sounding sound) generated in the mechanical clutch 40 can be attenuated by the elastic member 71.
  The action of the mechanical clutch 40 is the same as that of the other embodiments shown in FIGS.
[0045]
  In the above embodiment, other embodiments, and other embodiments, the elastic member 13 generates a relative torsional displacement between the input shaft 11 and the output shaft 15 in proportion to the steering torque. It is not limited to the torsion bar.
  The number of the first and second clutch mechanisms 41, 51, ... is not limited to three sets, but can be arbitrarily set.
[0046]
  The output member 34 may be any member that moves in the radial direction by being pressed by the other engaging members 62 when some of the engaging members 62 are disengaged. This is because if the output member 34 is pressed and moved by the other engagement members 62, the friction engagement force between the other engagement members 62 and the output member 34 can be reduced.
  The member that guides the radial movement of the output member 34 is not limited to the pin 14 and the straight portion 15 c of the output shaft 15.
  The elastic member that presses the output member 34 against the output shaft 15 is not limited to the compression spring 35, the shaft piece portion 15b, and the elastic pressing portion 71a, and may be a disc spring, for example.
[0047]
  The tapered space 61 may be formed between the inner peripheral surface of the input member 32b and the outer peripheral surface of the output member 34. The shape of the outer peripheral surface (engagement surface) of the output member 34 is also shown in FIG. The present invention is not limited to that shown in FIG. The inner peripheral surface of the input member 32b may be a predetermined polygon, and the outer peripheral surface of the output member 34 may be circular.
  The engaging member 62 only needs to be able to switch between engagement and disengagement with the circumferential end portion of the tapered space portion 61, and may be, for example, spherical in addition to the columnar shape.
  The urging member of the mechanical clutch 40 is not limited to the compression spring 65, and may be composed of, for example, a hard rubber material or a leaf spring.
[0048]
  Further, the first and second clutch mechanisms 41... 51 may be a friction engagement type clutch, for example, a known sprag type clutch.
  In the sprag clutch, an outer member (corresponding to the input member 32b) having a cylindrical inner peripheral engagement surface and an inner member (corresponding to the output member 34) having a cylindrical outer peripheral engagement surface are concentric. The two engaging surfaces are opposed to each other, a plurality of sprags (wedge action) are provided in the gap between them, and a member (position control member) connected to the steering wheel for positioning these sprags. 64) and a spring for biasing the sprags so as to wedge-engage toward the two engaging surfaces (such as a clutch device shown in Japanese Patent Laid-Open No. 1-188727).
[0049]
【The invention's effect】
  The present invention exhibits the following effects by the above configuration.
  In the first aspect of the invention, since the output member having a complicated shape for engaging the engaging member between the input and output members is constituted by a member different from the output shaft, the output member can be easily manufactured. High productivity.
  Further, 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 engaging members engaged with the output member is removed, the balance of the force pressing the output member with the engaging member is balanced. Collapse. For this reason, the output member is pressed in one direction by the other engaging member and moves in the radial direction. As a result, the frictional force between the output member and the other engaging member decreases, and the engagement is released. Thus, when a part of the clutch mechanisms is released, the other clutch mechanisms are also released with a reduced frictional force. Therefore, it can be reliably released with a smaller release force than releasing all the clutch mechanisms at once.
[0050]
  furtherClaim1In the described invention, the position control members of the plurality of sets of clutch mechanisms are arranged on the same circle while being separated from each other, and one set of the plurality of sets of clutch mechanisms is disengaged at an earlier timing than the other clutch mechanisms. Since the arc lengths of the position control members of one set of clutch mechanisms are set larger than those of the other position control members in order to achieve a combined state, only the arc lengths of the position control members of one set of clutch mechanisms are increased. With this simple configuration, only one set of clutch mechanisms can be easily released at an early timing. As a result, when one set of clutch mechanisms is released, the other clutch mechanisms are also released with a reduced frictional force. Therefore, it can be reliably released with a smaller release force than releasing all the clutch mechanisms at once.
[0051]
  Furthermore, since the invention according to claim 1 includes the elastic member that presses the output member against the output shaft, the output member moved in the radial direction is output by the elastic force of the elastic member after all the clutch mechanisms are released. It is possible to automatically return to the original neutral position with respect to the shaft. For this reason, the output member can be automatically and repeatedly moved in the radial direction, and therefore the clutch mechanism can be reliably released with a small releasing force any number of times.
[0052]
  According to the second aspect of the present invention, when only one set of clutch mechanisms is disengaged, the engagement of the output member that engages with the engagement member of another clutch mechanism so that the radial movement of the output member can be performed freely. Since the mating surface has a draft, when one set is released, the output member can move in the radial direction without any restriction. For this reason, just releasing one set of clutch mechanisms, It can be released more reliably.
[0053]
  Claim3In the described invention, since the elastic direction of the elastic member is matched with the moving direction of the output member, the elastic force of the elastic member can hold the output member in the original neutral position with respect to the output shaft. The output member does not rattle in the moving direction. As a result, although the output member and the output shaft are separated, no rattling noise or the like is generated and high quality can be maintained.
[0054]
  Claim4In the described invention, since the output member is held on the output shaft by the elastic member having a damping function such as rubber, the operation sound (sounding sound) generated in the clutch mechanism can be attenuated by the elastic member. For this reason, since the operating sound is difficult to be transmitted to the vehicle interior, the noise prevention effect is high, and the commercial value of the electric power steering device is increased.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of an electric power steering apparatus according to the present invention.
FIG. 2 is an enlarged sectional view of a main part of an electric power steering apparatus according to the present invention.
3 is a cross-sectional view taken along line 3-3 in FIG.
FIG. 4 is an exploded perspective view of a main part of an electric power steering apparatus according to the present invention.
5 is a cross-sectional view taken along line 5-5 of FIG.
FIG. 6 is an operation diagram of a mechanical clutch according to the present invention.
FIG. 7 is an operation diagram of a mechanical clutch according to the present invention.
FIG. 8 is an operation diagram of a mechanical clutch according to the present invention.
FIG. 9 is an operation diagram of a mechanical clutch according to the present invention.
FIG. 10 is a sectional view of a mechanical clutch (another embodiment) according to the present invention.
11 is a cross-sectional view taken along line 11-11 in FIG.
FIG. 12 is an operation diagram of a mechanical clutch (another embodiment) according to the present invention.
FIG. 13 is an operation diagram of a mechanical clutch according to the present invention (another embodiment).
FIG. 14 is an operation diagram of a mechanical clutch (another embodiment) according to the present invention.
FIG. 15 is an operation diagram of a mechanical clutch (another embodiment) according to the present invention.
FIG. 16 is a sectional view of a mechanical clutch (another embodiment) according to the present invention.
[Explanation of symbols]
  DESCRIPTION OF SYMBOLS 1 ... Electric power steering apparatus, 2 ... Steering handle, 5 ... Electric motor, 6 ... Torque transmission means, 9 ... Steering wheel (wheel), 11 ... Input shaft, 13 ... Elastic member (torsion bar), 15 ... Output shaft, 15b ... elastic member (shaft piece part), 15c ... straight part, 32b ... input member, 34 ... output member, 34a ... through hole, 35 ... elastic member (compression spring), 40 ... mechanical clutch, 41, 41A ... frictional engagement Combined clutch (first clutch mechanism), 51, 51A ... friction engagement clutch (second clutch mechanism), 61 ... tapered space, 62 ... engagement member, 64, 64A ... position control member, 65 ... biasing member (Compression spring), 71... Elastic member, 71a... Elastic member (elastic pressing portion).

Claims (4)

An input member connected to the electric motor and an output shaft with an output member connected to the steering wheel are connected via a plurality of sets of friction engagement clutch mechanisms, and these clutch mechanisms are engaged with the input / output members. An engagement member interposed between the input / output members, a position control member connected to the steering handle for positioning the engagement member, and a bias for biasing the engagement member toward the position control member An electric power steering device configured to switch an input / output member to an engagement / disengagement with an engagement member as the position control member rotates, and transmit auxiliary torque from the motor to the output shaft In
The output member and the output shaft are configured as separate members, and the output member is attached to the output shaft so as to be movable in a radial direction ,
Position control members of the plurality of sets of clutch mechanisms are arranged on the same circle while being separated from each other, and one set of the plurality of sets of clutch mechanisms is disengaged at an earlier timing than the other clutch mechanisms. In order to achieve this, the arc length of the position control member of the one set of clutch mechanisms is set larger than the other position control members,
An electric power steering apparatus comprising an elastic member that presses the output member against the output shaft . When only the one set of clutch mechanisms is disengaged, the output member engaging surface of the other clutch mechanism engages with the engaging member of the other clutch mechanism so as to freely move the output member in the radial direction. The electric power steering apparatus according to claim 1, wherein 3. The electric power steering apparatus according to claim 1, wherein an elastic direction of the elastic member is matched with a moving direction of the output member. It said output member, according to claim 1, claim 2 or claim 3 Symbol mounting of the electric power steering apparatus is characterized in that it is held in the output shaft by an elastic member having a damping function such as rubber.

Images