WO2008093861A1

WO2008093861A1 - Electric power steering device

Info

Publication number: WO2008093861A1
Application number: PCT/JP2008/051710
Authority: WO
Inventors: Toru Segawa; Haruhiko Kiyota
Original assignee: Nsk Ltd.
Priority date: 2007-01-30
Filing date: 2008-01-29
Publication date: 2008-08-07
Also published as: JPWO2008093861A1; JP2013121839A; JP5561388B2; JP2013126869A; JP5309997B2

Abstract

Provided is an electric power steering device, in which the output shaft of an electric motor and a worm are connected by a coupling. At the worm side end portion of the motor output shaft and the motor output shaft side end portion of the worm, there are alternately formed arm portions, which are disposed at a predetermined interval in a circumferential direction on the faces confronting each other in an axial direction and which protrude in the axial direction. The coupling is made of an elastic member, which has a plurality of holes formed to insert those arm portions individually and which has torque transmitting portions formed between the adjoining holes.

Description

Electric power steering device Technical field

The present invention relates to a torque transfer mechanism suitable for being provided in a torque transfer mechanism for transferring torque from an electric motor to a reduction mechanism or the like. The present invention detects the steering torque applied to the steering wheel with a torque sensor, and assist steering torque generated from the electric motor in response to the detected steering torque through the speed reduction mechanism, and the steering mechanism. The present invention relates to an electric power steering apparatus for transmitting power to an output shaft of a motor. Background art

In an electric power steering apparatus using an electric motor as a power source, an auxiliary steering torque generated from the electric motor in response to a steering torque applied to a steering wheel is steered through a power transmission mechanism including a reduction mechanism. It is transmitted to the output shaft of the mechanism.

In an electric power steering apparatus using a worm reduction gear as a power transmission mechanism comprising a reduction mechanism, a worm wheel is coupled to a worm connected to a drive shaft of an electric motor, and the worm wheel is connected to a steering mechanism. It is fitted on the shaft.

By the way, in the electric power steering apparatus disclosed in the table 2004-052712, the worm is biased to the worm wheel, and the output shaft of the worm and the motorized motor is splined at the center of the bearing that supports the worm. Combined with In addition, Japanese Patent Application Publication No. 2002-518242 discloses a motor-assisted steering device in which a motor rotor and an input shaft are connected by a flexible joint. In JP 2002-518242 A, the flexible joint comprises 16 radial bearings. It has a rubber spider with eight identical, circumferentially spaced arms that define a dynamic surface. The hub that supports the motor shaft at the end on the input shaft side is provided with four drive teeth that project axially toward the input shaft. Four drive teeth are engaged between the arms of the flexible joint. The cup formed at the end of the motor shaft of the input shaft is provided with four drive teeth that project axially toward the motor, and the four drive teeth are bent Engaged between the remaining arms of the fitting. In such a configuration, torque is transmitted from the motor rotor to the input shaft through the flexible joint. The flexible shaft allows the input shaft to move.

Further, according to Japanese Patent Application Laid-Open No. 2 0 535 1 9 9 2 2, the contact surface of the member that supports the pivot so as to be able to bias the worm shaft toward the worm wheel side with other members is the same. An electric power steering apparatus is disclosed which is formed by an elastic layer made of an inertia material. In Japanese Patent Application Laid-Open No. 2 0 5 3 1 9 9 2 2, the power transmission joint for connecting the output shaft of the electric motor and the ohmic shaft is interposed between the first and second engagement members of the power transmission joint. The power transmission surface of the transmission member is formed by the elastic layer.

In Japanese Patent Application Laid-Open No. 2 0 5 2 1 2 6 2 3 3, the output shaft and the worm shaft of the electric motor are connected so as not to cause defects such as abnormal noise and the like due to permanent distortion caused by deterioration with time. Of the power transmission surfaces of the transmission member connected by the power transmission coupling and interposed between the first and second engagement members, a part of the interference is increased relative to the interference of the remaining power transmission surfaces. An electric power steering apparatus is disclosed.

However, in the configuration described in the back surface of the table, if there is a large gap between the two splines, there is a problem that noise is generated due to the sound of tapping between the tooth surfaces. On the other hand, if the gap between the splines is small, there is a problem that the rocking motion of the worm is hindered and a tapping noise is generated on the gear tooth surface.

In addition, since the output shaft of the motorized motor and the accuracy of the spline of the worm are required, there is a problem that the cost becomes expensive and the performance varies depending on the accuracy of assembling the motorized motor. In the configuration described in JP-A-2002-518242, although the drive face of the flexible joint and the drive teeth provided on the hub allow deflection and eccentricity due to the slip pair, the contact state changes depending on the phase. The transmission angular velocity may change, and the torsional rigidity may differ.

In the configuration described in Japanese Patent Application Laid-Open No. 2005-319922 or Japanese Patent Application Laid-Open No. 2005-212623, there is a possibility that the rocking of the worm may be inhibited by the frictional resistance caused by the interference. Disclosure of the invention

The present invention has been made in view of the above-mentioned circumstances, and the output shaft of the worm motor drive system is not required to have precision, and the manufacturing cost can be reduced. It is an object of the present invention to provide an electric power steering device capable of obtaining stable performance without being affected by the assembly accuracy of the vehicle.

In order to achieve the above object, an electric power steering apparatus according to the present invention is characterized in that, in order to transmit an auxiliary steering torque generated from an electric motor to an output shaft of a steering mechanism via a worm reduction gear, In the electric power steering apparatus, the output shaft of the motor and the worm are coupled by a coupling disposed between respective opposite side ends,

The side end of the output shaft is provided at a predetermined interval in the circumferential direction, and a torque transmission portion formed of a torque transmission member axially projecting toward the worm is formed, and the side end of the worm The torque receiving portion is formed of a torque receiving member provided at predetermined intervals in the circumferential direction and axially projecting toward the output shaft, and the torque transmitting member and the torque receiving member have a circumferential shape. Alternately arranged in a direction, wherein the force-pulling is an elastic member that intervenes between the torque transmitting portion and the torque receiving portion, and transmits torque between the torque transmitting portion and the torque receiving portion. It is characterized by In the electric power steering apparatus according to the present invention, preferably, the elastic member has a portion extending at right angles to the axis, and the torque transmission member is inserted into the portion. A first opening having a torque receiving surface in contact with the transmission member and to which torque is transmitted from the torque transmission member, and the torque receiving member is inserted, and contacts the torque receiving member at the time of torque transmission to receive the torque receiving member. And a second opening having a torque transmission surface for transmitting torque to the member;

The first opening and the second opening each have a plurality of radially arranged holes.

Further, in the electric power steering apparatus according to the present invention, preferably, the elastic member forms a central hole connected to the plurality of radially arranged holes in a radiation central portion of the plurality of radially arranged holes. A cylindrical projection formed at the central end of the side end of the output shaft or the side end of the worm at the central hole is inserted and positioned.

Preferably, in the electric power steering device according to the present invention, the elastic member has an annular portion formed in an annular shape on the outer peripheral side of the connecting portion.

In the electric power steering apparatus according to the first aspect of the present invention, in order to transmit auxiliary steering torque generated from an electric motor to an output shaft of a steering mechanism via a worm reduction gear, In an electric power steering apparatus in which an output shaft and the worm are connected by couplings disposed between respective opposite side ends,

On the surfaces facing each other in the axial direction of the side end of the output shaft and the side end of the worm, arm portions protruding in the axial direction are alternately formed at predetermined intervals in the circumferential direction. Has been

The coupling is characterized in that it forms a plurality of holes for individually inserting these arm portions, and is made of an elastic body in which a torque transmission portion is formed between the adjacent holes. Preferably, in the electric power steering apparatus according to the first aspect of the present invention, the coupling has an annular portion formed in an annular shape on the outer peripheral side of the connecting portion.

Preferably, in the electric power steering apparatus according to the first aspect of the present invention, the arm formed at the side end of the output shaft and the side end of the worm extends in a radial direction. The plurality of holes in which the arms are inserted and the plurality of holes of the spring are formed radially.

In the electric power steering apparatus according to the first aspect of the present invention, preferably, the coupling has a central hole formed in a radial center portion of the radial hole and connected to the radial hole. A cylindrical projection formed at the center of the side end of the output shaft or the side end of the worm is inserted and positioned.

Preferably, in the electric power steering apparatus according to the first aspect of the present invention, the torque transmitting portion of the force plucking includes the side end surface of the output shaft and the side end of the ohmic member. A convex portion is in contact with at least one of the surfaces.

Preferably, the electric power steering apparatus according to the first aspect of the present invention includes a preloading mechanism for biasing the worm to a worm wheel.

Further, according to a second aspect of the present invention, there is provided an electric power steering apparatus, wherein: the electric steering wheel is configured to transmit auxiliary steering torque generated from the electric motor to an output shaft of a steering mechanism via a worm reduction gear. In the electric power steering apparatus, the output shaft of the evening and the worm are coupled by a coupling disposed between the respective opposite side ends,

The side end of the output shaft and the side end of the worm are provided with first and second connecting members each having a plurality of arms formed to engage with the pull-up,

The coupling includes a plurality of power transmission members having curved surfaces interposed between the arms and transmitting torque between the first and second connection members. The contact surface of the arm portion with the power transmission member may be configured by a curved surface having a smaller curvature than the power transmission member.

In the electric power steering apparatus according to the second aspect of the present invention, preferably, the curved surface of the arm portion has a substantially partially spherical recess.

Preferably, in the electric power steering apparatus according to the second aspect of the present invention, the power transmission member is circumferentially connected to the inner diameter side of the annular member, and the annular member is the annular member. It is biased toward the center of the member.

Preferably, the electric power steering apparatus according to the second aspect of the present invention includes a preloading mechanism for biasing the worm to a worm wheel.

Further, according to a third aspect of the present invention, there is provided an electric power steering apparatus comprising: an output shaft of the electric motor for transmitting auxiliary steering torque generated from the electric motor to an output shaft of a steering mechanism via a worm reduction gear. In the electric power steering apparatus, the motor and the worm are coupled by a coupling disposed between the respective opposite side ends,

On the side end of the output shaft and the side end of the worm, a plurality of axially projecting arms are formed at predetermined intervals in the circumferential direction on surfaces facing each other in the axial direction. First and second connecting members are provided;

The arm portions of the first connection member and the arm portions of the second connection member are alternately arranged in the circumferential direction,

A plurality of power transmission members, which are interposed between the adjacent arm portions and transmit torque between the first and second coupling members, are formed in the coupling at predetermined intervals in a circumferential direction,

The first and second connection members are provided with a restricting means for restricting the displacement of the power transmission member in the radial direction by the centrifugal force generated by the rotation of the output shaft of the motorized motor. I assume.

Preferably, in the electric power steering apparatus according to the third aspect of the present invention, The respective arm portions of the first and second connection members project in the circumferential direction from the outer diameter side of the surface on the circumferential direction side of the arm portion, and are disposed in the circumferential direction adjacent to the respective arm portions. A convex portion is formed in contact with a portion on the substantially outer diameter side of the power transmission member to restrict displacement of the power transmission member in the radial direction.

Preferably, in the electric power steering apparatus according to the third aspect of the present invention, the coupling has an annular member on the outer side in the radial direction of the power transmission member disposed in the circumferential direction. The power transmission member is integrally connected to the annular member in one-to-one correspondence with a plurality of support portions formed on the inner peripheral side of the annular member, and between the convex portion and the support portion There is always a gap.

Preferably, in the electric part steering system according to the third aspect of the present invention, the coupling has an annular member inward in a radial direction of the power transmission member disposed in the circumferential direction. The power transmission member is integrally connected to the annular member in one-to-one correspondence with a plurality of support portions formed on the outer peripheral side of the annular member, the first connecting member or the second connecting member A cylindrical portion for supporting the annular member is provided on one side.

In the electric power steering apparatus according to the third aspect of the present invention, preferably, there is always a gap between the support and the arm of the first and second connection members.

Preferably, the electric power steering apparatus according to the third aspect of the present invention includes a preloading mechanism for biasing the worm to a worm wheel.

Further, in the connection structure of the power transmission mechanism according to the present invention, the output shaft to be rotationally driven and the input shaft to which the rotational torque of the output shaft is transmitted are powers disposed between the respective opposite side ends. In the coupling structure of the rotation transmission mechanism coupled by the transmission member,

A first connecting member integrally rotatably connected to the output shaft is provided at the side end of the output shaft, and the side end of the input shaft is connected to the input shaft so as to be integrally rotatable. A second connecting member provided between the first and second connecting members, A power transmission member for transmitting torque between the first and second connection members is interposed between the first and second connection members, and the output shaft is provided in the first and second connection members. A restriction means is provided for restricting the radial displacement of the power transmission member due to the centrifugal force generated by the rotation of the motor.

According to the present invention, accuracy is not required for the output shaft of a worm or an electric motor, manufacturing cost can be reduced, and the motor motor is stable without being affected by assembly accuracy. Performance can be obtained.

According to the first aspect of the present invention, in addition to the above effects, stabilization of the contact state between the torque transfer portion of the coupling and the torque transfer surface of the arm portion can be achieved.

According to the second aspect of the present invention, in addition to the effects of the first aspect, it is possible to simplify the connection process between the motor and the motor. Also, the possibility of inhibiting the rocking of the worm can be reduced. In addition, displacement of the power transmission member can be prevented, and even if permanent distortion occurs in the power transmission member, occurrence of guarding can be prevented.

According to the third aspect of the present invention, in addition to the effects of the first and second aspects, at the time of torque transmission, the displacement of the power transmission member due to the centrifugal force is restricted, and the variation in torsional rigidity is reduced. It is possible to provide an electric power steering device capable of. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is an overall view showing a cross section of a part of a power assist portion of an electric parking steering apparatus according to a first embodiment of the present invention, and FIG. It is a cross-sectional view enlarging the main part of the

FIG. 2A is a view of the worm side connecting portion according to the first embodiment as viewed from the axial direction, and FIG. 2B is an axial view of the electric motor side connecting portion according to the first embodiment. FIG. 2C is a front view of the coupling portion of the coupling according to the first embodiment as viewed from the axial direction, and FIG. 2D is a modification of the first embodiment. FIG. 6 is a front view of the coupling portion of the coupling as viewed from the axial direction. 3A is a perspective view of the worm side connecting portion according to the first embodiment, FIG. 3B is a perspective view of the electric motor side connecting portion according to the first embodiment, and FIG. FIG. 3 is a cross-sectional view taken along line 3 c-3 c in FIG. 2C of the coupling portion of the coupling according to the first embodiment.

Fig. 4 shows a connecting portion in a state where the worm side connecting portion and the electric motor side connecting portion are connected via a coupling according to the first embodiment, taken along line 4c-4c in Fig. 2C. It is an expanded sectional view shown corresponding to a section.

FIG. 5 is a cross-sectional view of a portion of a power assist portion of the electric power steering apparatus according to the second embodiment.

6A is a partial perspective view of the connecting structure of the output shaft of the motorized motor and the worm shaft in the second embodiment, and FIG. 6B is a sectional view taken along the line A-A in FIG. It is the figure seen from.

FIG. 7 is a cross-sectional view of a portion of a power assist portion of an electric power steering apparatus according to a third embodiment.

FIG. 8 is an exploded perspective view of the connection structure between the output shaft of the electric motor and the worm shaft in the third embodiment.

FIG. 9 is a view of the connecting structure portion in the axial direction of the cross section taken along line A_A of FIG. 7 in the third embodiment.

FIG. 10 is a view of the linked structure in an axial direction in a cross section corresponding to the line A-A in FIG. 7 in the fourth embodiment. Embodiment of the Invention

Hereinafter, an electric power steering apparatus according to a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1A is an overall view showing a cross section of a part of a power assisting portion of an electric power steering apparatus according to a first embodiment of the present invention, and FIG. 1B is a cross-sectional view enlarging a main part of FIG. It is a front view.

Fig. 2A is a view of the worm side connecting portion as viewed in the axial direction, Fig. 2B is a view of the electric motor side connecting portion as viewed in the axial direction, and Fig. 2C is a view of the first embodiment. FIG. 2D is a front view of the coupling portion of the coupling according to the embodiment as viewed from the axial direction, and FIG. 2D is a front view of the coupling portion of the coupling according to the modification of the first embodiment as viewed from the axial direction.

3A is a perspective view of the worm side connecting portion, FIG. 3B is a perspective view of the electric motor side connecting portion, and FIG. 3C is a view of the connecting portion of the coupling according to the first embodiment. It is a 3 c- 3 c line sectional view in 2 C.

FIG. 4 is a cross-sectional view taken along line 4 c-4 c in FIG. 2 C, showing the connecting portion in the state where the worm side connecting portion and the electric motor side connecting portion are connected via the coupling in the first embodiment. Is an enlarged sectional view corresponding to FIG.

An electric motor 1, which is an auxiliary power source of the electric power steering apparatus, is fixed to the housing 2. In the housing 2, a worm 3 constituting a worm reduction gear and a worm wheel 4 fitted to the worm 3 are provided.

The worm 3 is supported on the housing 2 by two bearings 5, 6. The motor side bearing 5 is capable of rotating the worm 3 and is rockable with the motor side bearing 5 as a fulcrum and is supported so as not to move in the axial direction. The worm side bearing 6 is fitted with a gap between the inner ring 6 a and the worm 3.

Adjacent to the worm side bearing 6, there is provided a preload mechanism 7 for urging the worm 3 in the worm wheel 4 direction (the kneading direction) by the elastic body 7a, and from the tire (not shown) The hitting noise between the gear teeth of worm 3 and worm wheel 4 due to input is suppressed. In addition, since it is possible to use various well-known techniques, a detailed description is abbreviate | omitted.

The output shaft 8 of the motorized motor 1 is coupled to the worm 3 via a torque transmission coupling mechanism 20 which will be described in detail later, and transmits torque. Numeral 9 is a torque sensor. The rotation of the worm 3 is reduced via the worm wheel 4 which fits into the worm 3 It is quickly transmitted to the output shaft 1 1. The output shaft 11 is connected to the steering gear of the steering mechanism via a universal joint (not shown), a ground steering shaft and the like. A connecting portion 15 is provided at the stern end 3 a of the worm 3. The connecting portion 15 is formed on the center of the axis on the flat portion 16 radially extending at the motor side end, as shown in FIGS. 2A and 3A, and is axially directed toward the output shaft 8 of the electric motor 1. And a cylindrical portion 17 that protrudes into the The flat portion 16 is provided with at least two (three in the illustrated example) arm portions 19 extending substantially radially from the cylindrical portion 17 and axially projecting from the flat portion 16. . The arms 19 are formed on the flat portion 16 at equal intervals in the circumferential direction.

A flat torque receiving surface 19a is provided on one of the surfaces on both sides in the circumferential direction of each arm 19 so as to transmit torque with a force pulling 20 described later. The torque receiving surface 19a and the flat portion 16 are substantially perpendicular.

The outer diameter of the connecting portion 15 is the same diameter as the bearing press-in portion so as not to hinder the press-in of the motor-side bearing 5 or a small diameter within a range which does not affect the use of the retaining ring 23. On the other hand, a connecting portion 30 is provided at the end of the output shaft 8 facing the motor side end 3 a of the worm 3. The connecting portion 30 is a cylindrical portion axially projecting toward the worm side end portion 3 a at the axial center on the flat portion 32 extending in the radial direction of the shaft end as shown in FIGS. 2A and 3B. The flat portion 32 is provided with at least two (three in the illustrated example) arm portions 36 extending substantially radially from the axial center. The arm portions 36 are formed on the flat portion 32 at equal intervals in the circumferential direction. The connecting portion 30 on the output shaft 8 side is different from the connecting portion 15 on the warm 3 side, and the cylindrical portion 34 at the center of the axis and the arm portion 36 are not connected. Further, the axial length of the cylindrical portion 34 from the flat portion 32 is set to be shorter than the axial length of the arm 36 from the flat portion 32.

A torque transmission surface 3 6 a for transmitting torque to the coupling 20 is provided on both sides of the arm 36 in the circumferential direction. The torque transmission surface 3 6 a is a plane substantially perpendicular to the flat portion 32 of the connecting portion 30. In the present embodiment, the connecting portion 15 and the worm 3, and the connecting portion 30 and the output shaft 8 are respectively integrally molded, but in the case where it is desired to increase the diameter of the connecting portion in consideration of transmission of large torque, , Machining · If integral molding is difficult due to the convenience of assembly, etc., it may be a separate member. In that case, however, it is necessary to devise a fitting or fixing method such as serrations, press fitting, screwing, welding, etc. so that there is no rubbing in the rotational direction or axial direction. The shapes of the arms 19 and the arms 36 may be interchanged with each other. Both may be in the shape of arms 36. That is, 1. The arm of the connecting part 15 has the shape of FIG. 2A, FIG. 3B, and the arm of the connecting part 30 has the shape of FIG. 2B, FIG. 3B as in this embodiment. 2. Combinations in which the arms of the connector 15 have the shapes of FIGS. 2B and 3B, and the arms of the connector 30 have the shapes of FIGS. 2A and 3A, and 3. Both the arm part of the part 15 and the arm part of the connecting part 30 can be combined in three ways, as shown in FIGS. 2B and 3B.

The shaft end of the worm 3 configured as described above and the shaft end of the motor output shaft 8 are connected via a coupling 20.

The coupling 20 is a cylindrical elastic body as shown in FIGS. 2C and 3C. An axial hole 38 is formed in the axial center of the coupling 20 for positioning the connecting portion 15 and the connecting portion 30. A hole 40 extending substantially radially from the axial hole 38 is formed. Are formed continuously (in the present embodiment, six).

The cylindrical portion 17 of the connecting portion 15 is inserted into the axial hole 38 of the coupling 20 from the worm 3 side, and the cylindrical portion 34 of the connecting portion 30 is inserted from the output shaft 8 side. There is. In the radial holes 40, the arms 19 are alternately inserted from the side of the worm 3 and the arms 36 from the output shaft 8 side.

The radial holes 40 are formed including the number, phase, and thickness of the arms 19 and the arms 36. Therefore, when arm 19 and arm 36 are inserted, there is no space between torque receiving surface 19 a of arm 19 and torque transmitting surface 36 a of arm 36. It is set to have some or some margin. The generally fan-shaped small pieces 4 2 of the coupling 20, which are surrounded by adjacent radial holes 40, have a function of transmitting torque between the couplings. That is, the torque generated from the motorized motor 1 is transmitted to the arm 36 of the connecting portion 30 of the output shaft 8, and the small piece 42 is pushed from the torque transmitting surface 36 a to the coupling 20. Reportedly. The torque transmitted to the coupling 20 is transmitted through the small piece 4 2 and transmitted to the worm 3 by pressing the torque receiving surface 1 9 a of the arm 1 9 inserted into the adjacent radial hole 40. In this way, the torque generated from the electric motor 1 is transmitted to the worm 3.

In addition, the arm portion 19 of the connecting portion 15 and the arm portion 36 of the connecting portion 30 are in the form of the combination of the above-described 3 ·, that is, the arm portion 19 of the connecting portion 15 and the connecting portion 30 In the combined form in which both arms 36 have the shapes of FIGS. 2B and 3B, the coupling 20 is, as in the variant of FIG. 2D, an axial bore in which the cylindrical part 34 is inserted. An axial hole 41 into which the arm portion 36 is inserted is formed outward of the axial hole 38 in the radial direction of the axial hole 38 (six in this modification).

Since the coupling 20 is an elastic body, it is conceivable that deformation occurs during torque transmission and that torque is absorbed. In addition, it is conceivable that the endurance life becomes short due to repeated deformation. Therefore, an annular member 44 is disposed on the outer periphery of the coupling 20 to suppress deformation. The annular member 44 is made of a material such as metal, resin, or the like according to the required rigidity. Further, it is preferable that the annular member 44 be integrally fixed to the elastic material forming the small piece portion 42 by adhesion, slip molding, or the like.

The flat portion 16 of the worm 3 is in close contact with one surface in the axial direction of the small piece portion 42 of the coupling 20. The flat portion 32 of the output shaft 8 is in close contact with the other surface in the axial direction of the small piece 42.

A convex portion 14 is formed on at least one of two end faces in the axial direction of the small piece portion 42 of the coupling 20. In the present embodiment, the convex portion 14 is formed on the surface of the small piece portion 42 on the worm 3 side. As described above, since the flat portion 16 of the worm 3 is in close contact with one surface of the small piece portion 42 in the axial direction, the convex portion 14 is flat. It is axially compressed by the face portion 16 and the small piece portion 42 to generate a reaction force in the axial direction. By this reaction force, the internal clearance between the bearing 5 and the bearing 6 can be eliminated, and the generation of abnormal noise can be suppressed. When the convex portion 14 is formed on the surface on the output shaft 8 side of the small piece portion 42, the convex portion 14 is axially compressed by the flat portion 32 of the output shaft 8 and the small piece portion 42. As a result, an axial reaction force is generated.

From the above, in the present embodiment, the connection portions 15 and 30 of both the worm 3 and the output shaft 8 of the electric motor 1 allow eccentricity and swing due to deformation of the elastic body of the coupling 20. Therefore, the accuracy of the output shaft 8 of the worm 3 or the electric motor 1 is not required, the manufacturing cost can be reduced, and stable performance can be obtained without being affected by the assembling accuracy of the electric motor. Be

In this embodiment, although the preloading mechanism has been described as an electric power steering apparatus with a preloading mechanism as a countermeasure against the tapping noise of the gear tooth surface generated from the displacement of the shaft center of the worm and the shaft center of the output shaft. Regardless of the presence or absence, as described above, eccentricity and oscillation resulting from the drilling accuracy and the assembly accuracy can be suppressed inexpensively. Next, a second embodiment of the present invention will be described. In the second embodiment, a configuration different from the first embodiment will be described. The same reference numerals are used for the same configuration as that of the first embodiment.

FIG. 5 is a cross-sectional view of a portion of a power assist portion of the electric power steering apparatus according to the second embodiment. In the present embodiment, the structure for connecting the output shaft 8 of the motorized motor 1 and the worm 3 is different from that of the first embodiment.

6A is an exploded perspective view of the connecting structure of the output shaft 8 of the electric motor 1 and the worm 3 in the present embodiment, and FIG. 6B is a sectional view taken along the line A-A in FIG. It is the figure seen from.

A first connecting member 50 is provided at an end 8 a of the motor output shaft 8 on the worm 3 side. As shown in FIG. 6A, the first connecting member 50 includes a flange portion 51 disposed on the outer peripheral side of the output shaft 8, and a plurality of arm portions 52 formed on the flange portion 51. There is. The flange portion 51 is formed with a center hole 53 through which the end 8a of the output shaft 8 on the worm 3 side is passed. The central hole 53 is formed in a cylindrical fitting portion 54 axially projecting toward the worm 3. The end 8a on the worm 3 side of the output shaft 8 is fitted in the fitting portion 54, and the output shaft 8 and the first connecting member 50 are connected to rotate integrally.

The plurality of arm portions 52 of the flange portion 51 are formed on the surface 55 on the worm 3 side so as to axially project toward the worm 3 side. In the present embodiment, three arms 5 2 are formed. The arm portions 52 are formed on the surface 5 5 on the worm 3 side of the flange portion 51 at equal intervals in the circumferential direction. The arm 52 protrudes more than the fitting portion 54 toward the worm 3 side. The inner peripheral side of the arm portion 52 is continuous with the outer periphery of the fitting portion 54, and extends from the fitting portion 54 in the radial direction to a position having the same diameter as the outer periphery of the flange portion 51.

A torque transmission surface 52a is formed on both sides of the arm 52 in the circumferential direction. The torque transmitting surface 52 a is a curved surface having a predetermined curvature which is recessed inward of the arm 52. The curved surface of the torque transfer surface 5 2 a may be formed into a substantially partially spherical depression. The torque transmission surface 52a contacts the power transmission member 65 of the coupling 60 described later to transmit torque.

The second connecting member 70 having the same configuration as the first connecting member 50 is also connected to the end 3 a on the output shaft 8 side of the worm 3, and the worm 3 and the second connecting member 70 are integrated. Rotate. The second connecting member 70 is, as shown in FIG. 6A, similarly to the first connecting member 50, the flange portion 71, the central hole 73, and the central hole 73 toward the output shaft 8 And an extending fitting portion 74. A plurality of arms 72 are formed projecting on the surface 7 5 on the motor output shaft 8 side of the flange 7 1, and torque receiving surfaces 7 2 a are formed on both sides of the arm 72 in the circumferential direction. Is formed. The first connecting member 50 of the output shaft 8 and the second connecting member 70 of the worm 3 are connected via a coupling 60. The first connecting member 50 and the second connecting member 70 are formed on the side where the respective arm portions 52 and 72 are formed. The arm portions 52 of the first connecting member 50 and the arm portions 72 of the second connecting member 70 are disposed in such a manner as shown in FIG. 6B. As shown, they are arranged alternately in the circumferential direction. The first connecting member 50 and the second connecting member 70 are made of a highly rigid material such as metal.

As shown in FIG. 6A, the coupling 60 includes a plurality of power transmission members 65 that transmit torque between the first connection member 50 and the second connection member 70, and a power transmission member 65. It comprises a short cylindrical annular member 66 connected to the inner peripheral side.

The power transmission member 65 is made of a relatively low-rigidity elastic material and is formed into a substantially spherical shape. The material of the power transmission member 65 is preferably a rubber such as ditolyl rubber, silicone rubber, urethane rubber, an elastomer such as polyurethane, or a resin, but not limited thereto. As shown in FIG. 6B, the power transmission member 65 is disposed between the arms 52 and 72 of the first and second connection members 50 and 70 alternately arranged in the circumferential direction. It is done. More specifically, the torque transmission surface 5 2 a and the torque receiving surface 7 2 a that face each other in the circumferential direction of the arm portion 52 of the adjacent first connection member 50 and the arm portion 72 of the second connection member 70. It is arranged with a clearance in between. In the present embodiment, since three arms are formed on each of the first connection member 50 and the second connection member 70, six power transmission members 65 are disposed. .

The annular members 66 are, as shown in FIG. 6B, in the radial direction of the arms 52 of the first connection member 50 and the arms 72 of the second connection member 70 alternately arranged in the circumferential direction. It is located outside. On the inner circumferential side of the annular member 66, a plurality of support portions 67 projecting toward the center of the annular member 66 are provided at equal intervals in the circumferential direction. A power transmission member 65 is connected to an end of the support member 67 located on the center side of the annular member 66. Since the coupling 60 has such a configuration, it can not rotate relative to the first and second coupling members 50, 70. The annular member 66 pre-loads the coupled power transmission member 65 in the central direction of the annular member 66 in the assembled state. In the present embodiment, the annular member 66, the power transmission member 65, and the support portion 6 7 And are integrally formed.

Since the connection structure between the electric motor 1 and the worm 3 in the second embodiment is as described above, the torque transmission path is as follows. That is, the torque generated from the electric motor 1 is transmitted to the arm 52 of the first connecting member 50 connected to the output shaft 8, and the torque transmission surface 52 a of the arm 52 is coupled to the coupling 6. The power transmission member 0 is transmitted to the coupling 60 by pushing the power transmission member 6 5. The torque transmitted to the coupling 60 is transmitted to the power transmission member 65 and transmitted to the worm 3 in such a manner as to push the torque receiving surface 7 2 a of the arm 7 2 of the second transmission member 70. In this way, the torque generated from the electric motor 1 is transmitted to the worm 3.

The power transmission member 65 is formed into a substantially spherical shape as described above. Therefore, the portion of the power transmission member 65 that contacts the torque transmission surface 5 2 a of the arm 52 and the torque receiving surface 7 2 a of the arm 72 is partially spherical. The torque transmitting surface 52a and the torque receiving surface 72a formed on the arms 52 and 72 of the first and second connecting members 50 and 70 are the arms 52 and 7 as described above. It is a curved surface that is recessed toward the inside of 2. The curved surface constituting the torque transfer surface 52a and the torque receiving surface 72a is a curved surface having a curvature smaller than that of the power transfer member 65 of the coupling 60. Since the power transmission member 65, the torque transmission surface 52a and the torque receiving surface 72a have such a configuration, the power transmission member 65, the torque transmission surface 52a and the torque receiving surface 72a and The contacts are in surface contact with each other.

Also in the present embodiment, as in the first embodiment, eccentricity and rocking of the motor output shaft and the worm are permitted by the inertia deformation of the power transmission member of the coupling. Therefore, the accuracy of the worm and motor output shaft is not required, the manufacturing cost can be reduced, and stable performance can be obtained without being affected by the assembly accuracy of the electric motor.

Furthermore, in the present embodiment, by making the power transmission member of the coupling approximately spherical, the contact state between the power transmission member and the torque transmission surface and the torque receiving surface is stabilized. Can be implemented. That is, even if an angle or eccentricity occurs between both the motor output shaft and the worm shaft, the contact position between the power transmission member and the torque transmission surface and the torque receiving surface changes, but the contact state does not change. In other words, even if a declination or eccentricity occurs between the two axes, no local contact or contact occurs, and there is no change from surface contact to line contact. Therefore, stable transmission characteristics can always be maintained. Further, by making the power transmission member substantially spherical, the allowable angle for the phasing of the coupling in the connection process between the motorized motor and the worm is relaxed. As a result, the connection process between the electric motor and the worm can be simplified.

In the present embodiment, the torque transmitting surface and the torque receiving surface respectively formed on the arm portions of the first and second connecting members are curved surfaces having a curvature smaller than that of the power transmitting member of the coupling. Therefore, when high torque is transmitted, the contact area with the power transmission member can be increased, and stress can be relieved. When there is no torque transmission, or when transmitting low torque, the contact area is small, so the change in the elastic reaction force against the interference is small, and it is difficult for frictional resistance to occur. Therefore, the possibility of inhibiting the rocking of the worm is reduced.

The inertia reaction force of the power transmission member generates a force in the direction perpendicular to the torque transmission surface of the arm or the contact surface of the torque receiving surface with the power transmission member. In the case where the contact surface between the power transmission member and the torque transmission surface or the torque receiving surface is a flat surface, relative torsion occurs between the motor output shaft and the torque so that the contact surfaces are not parallel to each other. The force is applied to the power transmission member in the radial direction to cause displacement. On the other hand, in the configuration of this embodiment, since the contact surface is a curved surface and has a curvature, the elastic reaction of the power transmission member is directed substantially in the central direction of the power transmission member. For this reason, it is difficult to generate force in the radial direction, and it is difficult to generate displacement. Similarly, when the contact surface of the arm portion or the contact surface of the torque receiving surface with the power transmission member is configured as a substantially partial spherical recess, the power transmission member is displaced in the worm axial direction. It becomes difficult.

Also, even if the power transmission member is permanently strained, the annular member of the coupling Since the extension member is preloaded in the center direction of the annular member, the wedge effect between the curved surfaces on which the power transmission member is disposed does not cause the generation of gestation.

Next, a third embodiment of the present invention will be described. The third embodiment is substantially the same as the second embodiment, so a configuration different from the second embodiment will be described. The same symbols are used for the same configuration as the second embodiment.

FIG. 7 is a cross-sectional view of a portion of a power assist portion of an electric power steering apparatus according to a third embodiment. FIG. 8 is an exploded perspective view of the connection structure between the output shaft 8 and the worm 3 of the electric motor 1 according to the third embodiment. FIG. 9 is a view of the connecting structure portion in the axial direction taken along line A-A of FIG. 7 in the third embodiment.

In the present embodiment, an end 8a on the worm 3 side of the motor output shaft 8 and an end 3a on the output shaft 8 side of the worm 3 respectively have the first connection as in the second embodiment. A member 150 and a second connecting member 170 are provided. The first connecting member 150 integrally rotates with the output shaft 8, and the second connecting member 1 70 integrally rotates with the worm 3. The first connecting member 150 and the second connecting member 170 are connected by a coupling 160 as shown in FIG. The configuration of the coupling 160 is the same as that of the coupling 60 in the second embodiment, and can not be rotated relative to the first and second coupling members 150 and 170. There is.

The first connecting member 150 is, as shown in FIG. 8, a flange portion 15 1 disposed on the outer peripheral side of the output shaft 8 and a plurality of arm portions 1 5 2 formed on the flange portion 15 1. And have. The flange portion 15 1 is formed with a central hole 1 5 3 through which the end 8 a of the output shaft 8 on the worm 3 side is inserted. The hole 15 3 3 is formed in a cylindrical fitting 1 5 4 axially projecting toward the worm 3. The end 8 a of the worm 3 side of the output shaft 8 is fitted in the fitting portion 1 54.

The plurality of arm portions 1 5 2 of the flange portion 1 5 1 are formed so as to project in the axial direction toward the worm 3 side on the surface 1 5 5 on the worm 3 side. In the present embodiment, the arm Three parts 15 2 are formed. The arms 1 52 are formed on the surface 15 5 on the worm 3 side of the flange 1 5 1 at equal intervals in the inner circumferential direction. The arm portion 152 protrudes more than the fitting portion 154 toward the worm 3 side. The inner peripheral side of the arm portion 152 is continuous with the outer periphery of the fitting portion 154, and extends from the fitting portion 154 in the radial direction to a position having the same diameter as the outer periphery of the flange portion 151. ing.

Torque transmitting surfaces 1 5 2 a are formed on both sides of the arm 1 5 2 in the circumferential direction. The torque transmitting surface 1 52 2 a is a curved surface having a predetermined curvature which is recessed inward of the arm portion 1 5 2. The curved surface of the torque transmission surface 1 52 2 a may be formed into a substantially partially spherical depression. The torque transmission surface 1 5 2 a contacts the power transmission member 1 6 5 of the coupling 1 6 0 to perform torque transmission.

As shown in FIG. 8, the second connecting member 170 is, similarly to the first connecting member 150, the flange portion 1 71, the central ridge L 1 7 3 and the periphery of the central hole 1 7 3 And a fitting portion 1 74 that extends toward the output shaft 8. A plurality of arms 1 72 are formed projecting on the surface 1 7 5 on the side of the output shaft 8 of the flange 1 7 1, and torque receiving surfaces 1 are formed on both sides of the arms 1 2 2 in the circumferential direction. 7 2 a is formed. The first connecting member 150 of the output shaft 8 and the second connecting member 170 of the ohmic 3 are connected via a coupling 160. The first connecting member 150 and the second connecting member 170 are such that the surfaces 15 5 and 17 5 of the flange on the side on which the respective arms 1 52 and 1 72 are formed face each other. As shown in FIG. 9, the arm portions 152 of the first connecting member 150 and the arm portions 172 of the second connecting member 150 are alternately arranged in the circumferential direction. It is arranged as. The first connecting member 150 and the second connecting member 170 are made of a highly rigid material such as metal.

A portion of the torque transmitting surface 1 52 2 a formed on the arm portion 1 52 of the first connecting member 150 is protruded in the circumferential direction to form a convex portion 180. When the coupling 160 is assembled, the convex portion 180 projects toward a support portion 167 that supports the power transmission member 1 6 5 on the annular member 1 6 6. The surface 180a of the first connecting member 150 of the convex portion 180 on the axial center side is near the connecting portion between the power transmission member 165 and the support portion 167, and is substantially spherical. The power transmission member 165 is in contact with the power transmission member 165 at a portion that faces the inner periphery of the annular member 166 substantially in the radial direction. That is, a convex portion 1 8 0 is formed between the portion of the power transmission member 16 5 facing the inner peripheral side of the annular member 16 6 in the substantially radial direction and the inner peripheral side of the annular member 1 66. Is located.

The end face 1800 on the circumferential direction of the convex portion 180 does not contact the support portion 167 connecting the power transmission member 16.5 and the annular member 1660. Therefore, a gap 182 is present between the tip end surface 1803 of the convex portion 180 and the support portion 167. This gap 182 is set to exist even when transmitting the torque of the maximum specification. Similarly to the first connecting member 150, the portion of the torque receiving surface 1 72 2a formed on the arm portion 1 72 of the second connecting member 1 70 is also protruded in the circumferential direction to be convex like the first connecting member 150. It forms part 190.

The end face 1 90 b on the circumferential direction side of the convex portion 1 90 formed on the arm 1 72 of the second connecting member 1 7 0 also has the power transmission member 1 6 5 and the annular member 1 6 6 There is no contact with the support part 167 to be connected. Therefore, a gap 192 is present between the end face 1 90 b of the convex portion 190 of the second connecting member 1 70 and the support portion 1 6 7. This clearance 192 is set to exist even when transmitting the maximum specification torque.

Thus, the power transmission member 1 65 is a torque transmission surface 1 5 2 a of the first connection member 1 50 in the circumferential direction of the first and second connection members 1 5 0 and 1 7 0 in the circumferential direction. The second connecting member 1 70 respectively in contact with the torque receiving surface 1 7 2 a of the first connecting member 1 5 0 in contact with the annular member 1 6 6 substantially radially. The surface on the axial center side of the convex portion 180 formed on the axis 1 and the surface on the axial center side of the convex portion 190 formed on the arm portion 1 72 of the second connecting member 170. It is configured to be in contact with 90 a.

At the time of torque transmission, the torque of the power transmission member 16 is the torque of the first connection member 150 The first connecting member 1 is in contact with the transmission surface 15 2 2 a, the torque receiving surface 1 7 2 a of the second connecting member 1 70, and the convex portion 1 80 and the convex portion 1 90. Torque is transmitted between the contact surfaces of 50 and the second connecting member 1 70. At this time, although the centrifugal force by rotation acts on the power transmission member 1 65, the first connection member 1 5 0 is provided on the side of the power transmission member 1 6 that faces the annular member 1 6 6 in the substantially radial direction. Since the convex portion 180 formed on the arm portion 152 and the convex portion 190 formed on the arm portion 172 of the second connecting member 170 are in contact with each other, The displacement of the member 165 in the radial direction is restricted. On the other hand, since the gap 18 2 exists between the tip end surface 1 80 0 b on the circumferential direction of the projection 1 180 and the support portion 16 7 even when transmitting the torque of the maximum specification, the power There is no torque transmission between the transmission member 165 and the convex portion 180. Similarly, since a gap 192 is present between the tip end surface 1 90 b on the circumferential direction of the convex portion 190 and the support portion 16 7 even when torque of the maximum specification is transmitted, There is no torque transmission between the power transmission member 165 and the projection 190.

Since this embodiment has such a configuration, the movement of the power transmission member 165 in the radial direction is restricted when the output shaft 8 rotates, ie, when torque is transmitted, and the power transmission member 1 65 is the first connecting member. Torque transmission surface 1 5 2 a formed on arm portion 1 5 2 0 5 and torque receiving surface 1 7 2 a formed on arm portion 1 7 2 of second connecting member 1 7 0 Contact each other to transmit torque. As a result, in addition to the effects of the second embodiment, the effect of being able to reduce the variation in torsional rigidity is exhibited.

In steering the steering wheel, the operation of rotating the steering from the neutral state and repeatedly returning the steering to the neutral state is repeatedly performed. According to the configuration of the present embodiment, the change in torque feeling at each steering time The same steering feeling can always be obtained without

The present embodiment is not limited to the above-described electric power steering apparatus, but is a member used for a rotation transmission mechanism, which wants to restrict radial displacement due to centrifugal force. Is also applicable.

Next, a fourth embodiment of the present invention will be described. The fourth embodiment is substantially the same as the second embodiment and the third embodiment, and so a configuration different from these embodiments will be described. The same reference numerals are used for the same configuration as the second and third embodiments.

FIG. 10 is a view of the linked structure in an axial direction in a cross section corresponding to the line A-A in FIG. 7 in the fourth embodiment.

A first connecting member 20 0 and a second connecting member 2 20 are provided at an end 8 a of the worm 3 side of the motor output shaft 8 and an end 3 a of the output shaft 8 side of the worm 3 respectively. Is provided. The first connecting member 200 rotates integrally with the output shaft 8, and the second connecting member 220 rotates integrally with the ohm 3. In the fourth embodiment, the configurations of the first connecting member 200 and the coupling 230 are different from those of the second embodiment.

At a central portion of the flange portion 201 of the first connecting member 200, a cylindrical portion 240 projecting in the axial direction is formed. The cylindrical portion 240 is disposed radially inward of the plurality of arm portions 202 of the first connecting member 200 disposed at predetermined intervals in the circumferential direction. The outer peripheral side of the cylindrical portion 240 and the inner peripheral side of the arm portion 202 are not continuous, and the cylindrical portion 240 projects in the same direction as the arm portion 202 toward the worm 3 direction. The configuration is different from the fitting portion 54 and the arm portion 52 in the second embodiment. The end 8 a of the output shaft 8 is internally fitted on the inner peripheral side of the cylindrical portion 240. The configuration of the second connecting member 220 is the same as the configuration of the second connecting member 72 in the second embodiment.

The first connecting member 200 and the second connecting member 220 are connected by a coupling 230 as shown in FIG. As shown in FIG. 10, the coupling 230 in the present embodiment includes a plurality of power transmission members that perform torque transmission between the first connection member 200 and the second connection member 220. 5 and an annular member 2 32 in which a power transmission member 2 6 5 is linked on the outer peripheral side. A cylindrical portion 2 40 formed in the first connecting member 200 is penetrated on the inner peripheral side of the annular member 2 32 to support the annular member 2 32. The annular members 2 32 are radially inward of the arm portions 2 0 2 of the first connection member 2 0 0 and the arm portions 2 2 2 of the second connection member 2 0 2 arranged alternately in the circumferential direction. Is located in On the outer periphery of the annular member 232, a plurality of support portions 223 projecting toward the outer diameter direction of the annular member 232 are provided at equal intervals in the circumferential direction. A power transmission member 2 6 5 is connected to each of the support portions 2 3 5 at an end portion of the annular member 2 3 2 that is radially outward. The coupling 230 can not rotate relative to the first and second coupling members 200 0 and 220. The end portion 2 0 2 b of the arm portion 2 0 2 formed on the first connecting member 2 0 0 is not formed with a portion corresponding to the convex portion 1 8 0 in the third embodiment. Therefore, there is no contact with the support portion 2 3 5 connecting the force transfer member 2 6 5 and the annular member 2 3 2. Therefore, a gap 2 3 8 exists between the end 2 0 0 2 b near the inner peripheral side of the arm 2 0 2 2 and the support 2 3 5. This clearance 2 3 8 is set to exist even when transmitting the maximum specification torque. The end 22 2 b of the arm 22 2 formed on the second connecting member 220 is also not in contact with the support 23 5 in the same manner. A gap 2 4 8 exists between the end 2 2 2 b closer to the inner circumferential side and the support portion 2 3 5.

At the time of torque transmission, a torque transmission surface 2 0 2 a formed with the power transmission member 2 6 5 on the arm 2 0 2 of the first connection member 2 0 0 2 and an arm 2 2 0 of the second connection member 2 2 0 By being in contact with the torque receiving surface 2 2 2 a formed in 2, the torque is transmitted between the first connecting member 2 0 0 and the second connecting member 2 2 0. At this time, although the centrifugal force by rotation acts on the power transmission member 2 6 5, since the power transmission member 2 6 5 is connected to the annular member 2 3 2 by the support portion 2 3 5, the power transmission member 2 6 5 The radial displacement of 2 6 5 is restricted.

On the other hand, since the gap 2 3 8 exists between the arm 2 0 2 0 of the first connecting member 2 0 0 0 and the support 2 3 5 even when transmitting the torque of maximum specification, the arm 2 0 2 and support part There is no transmission of torque between 2 3 5. Similarly, since a gap 2 4 8 exists between the arm 22 2 of the second connecting member 2 20 and the support 2 3 5 even when transmitting the torque of the maximum specification, the arm 2 There is no torque transmission between the 2 2 2 and the support 2 3 5.

Since this embodiment has such a configuration, when the output shaft 8 rotates, that is, when torque is transmitted, the radial movement of the power transmission member 2 65 is restricted, and the power is the same as in the third embodiment. The transmission member 2 6 5 is a torque transmission surface 2 0 2 a formed on the arm 2 0 2 of the first connection member 2 0 0 and a torque formed on the arm 2 2 2 of the second connection member 2 2 0 The torque is transmitted each time by contacting approximately the same place on each of the transmission surfaces 22 2 a. As a result, as in the third embodiment, in addition to the effects of the second embodiment, the effect of being able to reduce the variation in torsional rigidity can be exhibited.

As in the third embodiment, this embodiment is not limited to the above-described electric power steering device, but may be any member used in the rotation transmission mechanism for restricting radial displacement due to centrifugal force. It is applicable.

Claims

The scope of the claims

1. The output shaft of the electric motor and the worm face each other in order to transmit the assist steering torque generated from the electric motor to the output shaft of the steering mechanism via the worm reduction gear. In the electric power steering apparatus coupled by a coupling disposed between the side ends,

The side end portion of the output shaft is formed at a predetermined interval in a circumferential direction, and a torque transmission portion formed of a torque transmission member axially projecting toward the worm is formed, and the worm of the worm The side end portion is provided with a torque receiving portion formed of a torque receiving member provided at a predetermined interval in the circumferential direction and axially projecting toward the output shaft, and the torque transmitting member and the torque receiving member Are alternately arranged in the circumferential direction,

The electric power steering apparatus according to any one of claims 1 to 6, wherein the force plucking is an elastic member that is interposed between the torque transmitting unit and the torque receiving unit and that transmits torque between the torque transmitting unit and the torque receiving unit.

2. The elastic member has a portion extending at right angles to the axis, and the torque transfer member is inserted into the portion, and the torque transfer member contacts the torque transfer member at the time of torque transfer to transmit torque from the torque transfer member. A second opening having a torque receiving surface, the torque receiving member being inserted, and a torque transmitting surface contacting the torque receiving member at the time of torque transmission and transmitting the torque to the torque receiving member; With an opening,

The electric power steering apparatus according to claim 1, wherein the first opening and the second opening each have a plurality of radially arranged holes.

3. The elastic member is disposed on the radiation center of the plurality of radially arranged holes. A cylindrical hole formed in the center of the side end of the output shaft or in the center of the side end of the worm. The electric power steering apparatus according to claim 2, characterized in that:

4. The electric power steering device according to any one of claims 1 to 3, wherein the elastic member has an annular portion formed in an annular shape on the outer peripheral side of the connection portion.

5. The output shaft of the electric motor and the worm are opposed to each other in order to transmit the auxiliary steering torque generated from the electric motor to the output shaft of the steering mechanism via the worm reduction gear. In the electric power steering apparatus connected by a coupling disposed between the ends,

On the surfaces facing each other in the axial direction between the side end of the output shaft and the side end of the worm, arm portions protruding in the circumferential direction are provided alternately at predetermined intervals in the circumferential direction. Is formed,

The electric power steering includes an elastic body in which a plurality of holes for individually inserting the arms are formed, and the torque transmitting portion is formed between the adjacent holes. apparatus.

6. The electric joint steering system according to claim 5, wherein the force-pulling includes an annular portion formed in an annular shape on an outer peripheral side of the connection portion.

7. The arms formed at the side end of the output shaft and the side end of the worm extend in a radial direction, and the holes of the coupling into which the arms are inserted are: The electric power according to claim 5, wherein the electric power is formed radially. Steering device.

8. The coupling has a central hole formed in the radial central portion of the radial hole and connected to the radial hole, and the central hole forms a center of the side end of the output shaft or the center of the side end of the worm. The electric power steering apparatus according to claim 7, wherein the cylindrical projection formed in the portion is positioned in a wedged manner.

9. The torque transmission portion of the coupling has a convex portion in contact with at least one of the side end surface of the output shaft and the side end surface of the worm. The electric power steering apparatus according to claim 5.

10. The electric joint steering system according to any one of claims 5 to 9, further comprising a preloading mechanism for urging the worm toward the worm wheel.

1 1. The output shaft of the electric motor and the worm are opposed to each other at the opposite end in order to transmit the auxiliary steering torque generated from the electric motor to the output shaft of the steering mechanism via the worm reduction gear. In the electric power steering apparatus connected by a coupling disposed between the parts,

The side end portion of the output shaft and the side end portion of the worm are provided with first and second connecting members each having a plurality of arm portions engaged with the force-pulling,

The coupling is formed with a plurality of power transmission members having curved surfaces interposed between the arms and transmitting torque between the first and second coupling members.

An electric power steering apparatus characterized in that a contact surface of the arm with the power transmission member is formed by a curved surface having a curvature smaller than that of the power transmission member.

12. The electric power steering apparatus according to claim 11, wherein the curved surface of the arm portion has a substantially partial spherical recess.

The power transmission member is circumferentially connected to the inner diameter side of the annular member, and the annular member biases the power transmission member in the central direction of the annular member. The electric power steering apparatus according to 1.

1 4. The electric power steering apparatus according to any one of claims 1 to 13, further comprising a preloading mechanism for urging the worm toward the worm wheel.

1 5. The output shaft of the electric motor and the worm are opposed to each other at the opposite end in order to transmit the auxiliary steering torque generated from the electric motor to the output shaft of the steering mechanism via the worm reduction gear. In a power steering system connected by a coupling disposed between the parts,

On the side end of the output shaft and the side end of the worm, a plurality of axially projecting arm portions are formed at predetermined intervals in the circumferential direction on surfaces facing each other in the axial direction. First and second connection members are provided,

The first and second connection members are provided with restriction means for restricting radial displacement of the front third power transmission member due to centrifugal force generated by rotation of the output shaft of the electric motor. An electric power steering apparatus characterized by

The respective arm portions of the first and second connecting members project in the circumferential direction from the outer diameter side of the surface on the circumferential direction side of the arm portion, and are adjacent to the respective arm portions, circumferential direction A convex portion is formed in contact with a portion on the substantially outer diameter side of the power transmission member disposed on the rear surface, and which restricts the displacement of the power transmission member in the radial direction.

The electric power steering apparatus according to 15.

The coupling has an annular member on the outer side in the radial direction of the power transmission member disposed in the circumferential direction, and the power transmission member is formed on the inner circumferential side of the annular member. 17. The electric power according to claim 16, characterized in that a plurality of support portions and one-to-one are integrally connected to the annular member, and a gap is always present between the convex portion and the support portion. Steering device.

The coupling has an annular member inward in the radial direction of the power transmission member disposed in the circumferential direction, and the power transmission member is formed on the outer peripheral side of the annular member. A cylindrical portion that is integrally connected to the annular member in one-to-one correspondence with the support portion of the second support member, and supports the annular member on one of the first connection member or the second connection member. The electric power steering device according to claim 15, characterized in that:

The electric power steering apparatus according to claim 18, wherein a gap is always present between the support portion and the arm portions of the first and second connection members.

20. The electric power steering apparatus according to any one of claims 15 to 19, further comprising a preloading mechanism that biases the worm toward the worm wheel.

The output shaft to be rotationally driven and the input shaft to which the rotational torque of the output shaft is transmitted are In a coupling structure of a rotation transmission mechanism coupled by a power transmission member disposed between respective opposite side ends,

The side end of the output shaft is provided with a first connecting member integrally rotatably coupled to the output shaft, and the side end of the input shaft is integrally rotatably coupled to the input shaft A second connecting member is provided,

Between the first and second connecting members, there is interposed a power transmission member that can not rotate relative to the first and second connecting members and performs torque transmission between the first and second connecting members.

A power transmission mechanism characterized in that the first and second connection members are provided with a regulation means for regulating the displacement of the power transmission member in the radial direction due to the centrifugal force generated by the rotation of the output shaft. Connection structure.