JP2011226592A - Transmission ratio variable device and vehicular steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission ratio variable device and a vehicular steering device, allowing reduction of vibration/noise accompanying operation of a differential mechanism by excellently maintaining a meshing state of the differential mechanism.SOLUTION: This transmission ratio variable device 12 includes a tubular housing 21 storing a wave gear mechanism 16 and a motor, and rotatably supports a second shaft 15 to an annular support member 46 provided in the housing 21 through a bearing 47. The support member 46 can be installed to the second shaft 15 in a state that the shaft center L4 of the support member 46 and the shaft center L1 of the second shaft 15 are brought into line. The transmission ratio variable device 12 includes a connection member 51 connecting the support member 46 and the housing 21 such that they cannot be relatively moved while maintaining a state that the support member 46 is provided in the housing 21 such that the shaft center L5 of the bearing 47 come into line with the shaft center L1 of the second shaft 15.

Description

  The present invention relates to a transmission ratio variable device and a vehicle steering device.

  2. Description of the Related Art Conventionally, there is a transmission ratio variable device that uses a differential mechanism to add rotation based on motor drive to rotation of an input shaft based on a steering operation and transmit the rotation to an output shaft. Such transmission ratio variable devices include a housing-integrated rotation type in which a housing that houses a motor and a differential mechanism rotates together with an input shaft (see, for example, Patent Document 1), and a housing in a non-rotating part of a vehicle. There is a fixed housing type (for example, see Patent Document 2).

  In a housing-integrated rotation type transmission ratio variable device described in Patent Document 1, an output shaft connected to a differential mechanism is provided so as to protrude from a cylindrical housing, and the output shaft is a lower end portion of the housing. It is rotatably supported via a bearing on an annular support member (boss portion) fixed to the base. Such a transmission ratio variable device is assembled in such a manner that a motor and a differential mechanism are accommodated in a housing, and a bearing provided on a support member is externally fitted to the output shaft in a state where the output shaft is coupled to the differential mechanism. . The support member is fixed to the housing by being press-fitted into the lower end of the housing.

  On the other hand, in the housing-fixed transmission ratio variable device described in Patent Document 2, the cylindrical housing that houses the motor and the differential mechanism is fixed to the lower housing fixed to the rack housing and to the upper end of the lower housing. The upper housing is divided and formed. An input shaft connected to the differential mechanism is provided so as to protrude from the upper end of the upper housing, and the input shaft is rotatably supported on the upper end portion of the upper housing via a bearing. The assembly of such a transmission ratio variable device is such that a bearing is externally fitted to an input shaft and a differential mechanism and a motor are accommodated inside the differential mechanism and motor to which the input shaft is coupled. The housing is fixed to the lower housing.

JP 2003-306155 A (paragraph [0042] etc., FIG. 3) JP 2008-87599 A

  By the way, in the transmission ratio variable device described in Patent Document 1, since the output shaft is connected to a differential mechanism assembled to the motor, the shaft center of the output shaft is the motor shaft center ( It is provided so as to coincide with the axis of the motor shaft. On the other hand, the bearing that supports the output shaft is fixed to the support member, and the support member is directly fixed to the housing by press-fitting or the like, so that the axis of the support member matches the axis of the housing. Therefore, the bearing is provided so that its axis coincides with the axis of the housing.

  Here, the motor is housed in the housing so that its axis is coaxial with the axis of the housing. However, due to the dimensional accuracy of the motor and the housing, the motor axis and the housing axis are not necessarily required. Does not always match. In this case, the output shaft is supported in a state in which the shaft center is deviated with respect to the bearing, and the load is received from the bearing. As a result, when a load is applied to the meshing portion of the differential mechanism, there is a possibility that vibration and noise associated with the operation increase.

  In the transmission ratio variable device disclosed in Patent Document 2, the shaft center of the input shaft is provided so as to match the shaft center of the motor, and the shaft center of the bearing matches the shaft center of the housing (upper housing). Provided. For this reason, the above-described problem can occur in the same manner even in a housing-fixed type as shown in Patent Document 2.

  The present invention has been made to solve the above-mentioned problems, and its purpose is to maintain a good meshing state of the differential mechanism and to reduce the vibration and noise associated with its operation. An apparatus and a steering apparatus for a vehicle are provided.

  In order to achieve the above object, a first aspect of the present invention provides a differential mechanism that adds rotation based on motor driving to rotation of an input shaft and transmits it to an output shaft, and a cylinder that houses the differential mechanism and the motor. And the input shaft or the output shaft is a transmission ratio variable device that is rotatably supported by a ring-shaped support member provided in the housing via a bearing. A connecting member for connecting a member to the housing is provided, and the support member can be attached to either the input shaft or the output shaft so that the shaft center of the bearing coincides with the one shaft center. The coupling member holds the support member and the housing while maintaining a radial relative position between the support member and the housing in a state where the shaft center of the bearing and the one shaft center coincide with each other. Can not move relative to each other And summarized in that those be connected to.

  According to the above configuration, the support member and the housing are connected in a state in which the relative position in the radial direction is maintained in a state in which the shaft center of the bearing is coincident with any one of the input shaft and the output shaft. The members are connected so as not to move relative to each other. That is, the support member is fixed to the housing via the connecting member in a state where the shaft center of the bearing is coincident with one of the input shaft and the output shaft. For this reason, even when the differential mechanism and the motor are housed in the housing in a state where the shaft centers of the motor and the housing do not coincide with each other, either the input shaft or the output shaft is in contact with the bearing. It is possible to prevent the shaft center from being supported in a shifted state. Therefore, the meshing state of the differential mechanism can be maintained satisfactorily, and vibration and noise associated with the operation can be reduced.

  According to a second aspect of the present invention, in the transmission ratio variable device according to the first aspect, the support member extends in a radially outer side from the cylindrical main body portion on which the bearing is provided, and the main body portion. An extension portion, and the connecting member extends inward in the radial direction from the fixing portion and clamps the extension portion between the housing and the tubular fixing portion fixed to the housing. The extending portion is formed so as to be loosely fitted in the fixed portion, and a restricting means for restricting movement of the support member in the radial direction and the circumferential direction is provided. The gist.

  According to the above configuration, the support member is fixed so as not to move in the axial direction with respect to the housing by the extension portion being sandwiched between the housing and the sandwiching portion. The support member is fixed so as not to move in the radial direction and the circumferential direction with respect to the housing by the movement of the support member being restricted in the radial direction and the circumferential direction by the restriction means. Thus, since a connection member consists of a cylindrical fixing | fixed part and a clamping part, the same connection member can be made into a simple structure.

  According to a third aspect of the present invention, in the transmission ratio variable device according to the second aspect, the restricting means includes a recess formed on a contact surface that contacts the clamping portion of the extension portion, and the bearing. A convex portion formed by plastically deforming the clamping portion so as to engage with the concave portion in a state where the support member is provided with respect to the housing so that an axis coincides with the one axial center; The gist is that movement of the support member in the radial direction and the circumferential direction is restricted by engaging the convex portion with the concave portion.

  According to the above configuration, the support member is moved in the radial direction and the circumferential direction by engaging the convex portion formed by plastically deforming the clamping portion with the concave portion formed on the contact surface of the extension portion. Is regulated. Thus, since the restricting means is constituted by the concave portion and the convex portion, the support member can be fixed to the housing so as not to move in the radial direction and the circumferential direction without increasing the number of parts.

  According to a fourth aspect of the present invention, in the transmission ratio variable device according to the third aspect, the contact surface of the extension portion and the contact surface that contacts the extension portion of the clamping portion are low The gist is that each surface treatment is performed to have a friction coefficient.

  According to the above configuration, since each contact surface is surface-treated so as to have a low friction coefficient, for example, in the case where the convex portion is formed by caulking the clamping portion, the connecting member is changed to the support member. The acting frictional force is reduced, and the relative position of the support member relative to the housing can be suppressed from shifting.

The gist of the fifth aspect of the present invention is the transmission ratio variable device according to any one of the first to fourth aspects, wherein the bearing is a cross roller bearing.
According to the above configuration, since the bearing is constituted by the cross roller bearing, the load in the radial direction and the thrust direction can be received by one bearing, and the apparatus can be reduced in size.

The gist of the sixth aspect of the invention is a vehicle steering apparatus including the transmission ratio variable device according to any one of the first to fifth aspects.
According to the above configuration, since the meshing state of the differential mechanism of the transmission ratio variable device can be kept good and vibrations and noises associated with its operation can be reduced, a vehicle steering device with excellent quietness is provided. Can do.

  ADVANTAGE OF THE INVENTION According to this invention, the transmission ratio variable apparatus and vehicle steering apparatus which can maintain the meshing state of a differential mechanism favorable and can reduce the vibration and noise accompanying the operation | movement can be provided.

The schematic block diagram of the steering apparatus for vehicles. Sectional drawing of the transmission ratio variable apparatus of 1st Embodiment. The expanded sectional view near the supporting member of a 1st embodiment. The expanded sectional view of the support member vicinity in the state before assembling the connection member of 1st Embodiment. The expanded sectional view of the support member vicinity in the state after attaching the connecting member of 1st Embodiment. Sectional drawing of the transmission ratio variable apparatus of 2nd Embodiment. The expanded sectional view of the support member vicinity of 2nd Embodiment.

(First embodiment)
Hereinafter, a first embodiment in which the present invention is embodied in a vehicle steering apparatus provided with a so-called housing-integrated rotation type transmission ratio variable device in which a housing rotates integrally with an input shaft will be described with reference to the drawings.

  As shown in FIG. 1, in the vehicle steering apparatus 1, a steering shaft 3 to which a steering 2 is fixed meshes with a rack shaft 6 that is reciprocally inserted into a rack housing 5 via a rack and pinion mechanism 4. Has been. Thereby, the rotation of the steering shaft 3 accompanying the steering operation is converted into the reciprocating linear motion of the rack shaft 6 by the rack and pinion mechanism 4. The steering shaft 3 is formed by connecting a column shaft 8, an intermediate shaft 9, and a pinion shaft 10. The rudder angle of the steered wheels 11, that is, the traveling direction of the vehicle is changed by the reciprocating linear motion of the rack shaft 6.

  Further, the vehicle steering apparatus 1 includes a transmission ratio variable device 12 that varies the ratio of the steering angle (tire angle) of the steered wheels 11 to the steering angle (steering angle) of the steering wheel 2, that is, a transmission ratio (gear ratio). Yes.

  The transmission ratio variable device 12 of the present embodiment is provided on the intermediate shaft 9 constituting the steering shaft 3. Specifically, the intermediate shaft 9 includes a first shaft 14 as an input shaft positioned on the steering 2 side and a second shaft 15 as an output shaft positioned on the rack shaft 6 side. The transmission ratio variable device 12 includes a wave gear mechanism 16 as a differential mechanism that connects the first shaft 14 and the second shaft 15, and a motor 17 that drives the wave gear mechanism 16. Thereby, the transmission ratio variable device 12 adds the rotation based on the drive of the motor 17 to the rotation of the input shaft accompanying the steering operation and transmits it to the output shaft, thereby transmitting between the steering wheel 2 and the steered wheels 11. The ratio is made variable.

  More specifically, as shown in FIG. 2, the transmission ratio variable device 12 has a substantially cylindrical housing 21 and a bottomed cylindrical shape that closes an opening 21a on the input side (upper side in FIG. 2) of the housing 21. The upper lid part 22 is provided with a cylindrical connecting part 23 at a position coaxial with the housing 21. One end of the first shaft 14 is connected to the connecting portion 23 via a joint 24. Therefore, the housing 21 is connected to the first shaft 14 so as to be rotatable integrally with the first shaft 14, and constitutes an input shaft together with the first shaft 14.

  The motor 17 is accommodated in the housing 21 so as to be coaxial with the housing 21. Specifically, the substantially bottomed cylindrical casing 25 is fixed so as to be coaxial with the housing 21, and the substantially bottomed cylindrical casing 26 is fixed to the upper lid portion 22 in the upper lid portion 22. Has been. The stator 27 of the motor 17 is fixed to the inner peripheral surface of the casing 25, while the rotor 28 of the motor 17 is inner peripheral surfaces of the casings 25 and 26 so as to be coaxial with the stator 27 (housing 21). Are supported so as to be relatively rotatable with respect to the housing 21 via ball bearings 31 and 32 provided on the housing. The rotor 28 is provided with a motor shaft 33 so as to rotate integrally with the rotor 28 in a state where the motor shaft 33 protrudes from the casing 25 toward the second shaft 15 (the lower side in FIG. 2).

  The upper lid portion 22 is provided with a spiral cable device 34. The spiral cable device 34 electrically connects the motor 17 and an ECU (not shown) for controlling the operation of the motor 17 within a predetermined rotation range (allowable rotation range).

  On the other hand, the wave gear mechanism 16 is juxtaposed on the second shaft 15 side in the axial direction of the motor 17. More specifically, the wave gear mechanism 16 includes a stay circular spline 41 and a drive circular spline 42 that are coaxially arranged, and a cylindrical flex spline 43 that is coaxially disposed so as to partially mesh with each of the circular splines 41 and 42. And a wave generator 44 that rotates the meshing portion of the flex spline 43 by driving the motor.

  The circular splines 41 and 42 are each formed in a cylindrical shape, and are arranged in parallel with the motor shaft 33 via a wave generator 44. A large number of internal teeth are formed on the inner peripheral surfaces of these circular splines 41 and 42, and different numbers of teeth are set. The stay circular spline 41 disposed on the first shaft 14 side is fixed to the housing 21 so as to be coaxial with the housing 21. On the other hand, the drive circular spline 42 disposed on the second shaft 15 side is coaxially connected to the second shaft 15 via the intermediate member 45. The intermediate member 45 is connected to the second shaft 15 so as to be rotatable integrally with the second shaft 15 and constitutes an output shaft together with the second shaft 15. The second shaft 15 is rotatably supported via a bearing 47 with respect to an annular support member 46 provided at the lower end portion 21 b on the output side (lower side in FIG. 2) of the housing 21.

  The flex spline 43 is configured to have flexibility by being formed into a thin cylindrical shape, that is, can be elastically deformed, and meshes with the inner teeth of the circular splines 41 and 42 on the outer peripheral surface thereof. A large number of external teeth are formed. The flex spline 43 is disposed inside each of the circular splines 41 and 42 in a state of being bent in a substantially elliptical shape by the wave generator 44. Thereby, the outer teeth of the flexspline 43 are partially meshed with the inner teeth of the circular splines 41 and 42, respectively. In this embodiment, the number of teeth of the stay circular spline 41 is set equal to the number of teeth of the flex spline 43, and the number of teeth of the drive circular spline 42 is the number of teeth of the stay circular spline 41 (flex spline 43). Set less than the number.

  The wave generator 44 includes an elliptical cam 44 a that is spline-fitted to one end of the motor shaft 33, and a thin ball bearing 44 b that is externally fitted to the cam 44 a, and the flex spline so as to be coaxial with the motor 17. 43 is disposed inside. The inner ring of the ball bearing 44b is fixed to the outer peripheral surface of the cam 44a, and the outer ring is configured to be elastically deformed via the ball. Then, when the cam 44a rotates together with the motor shaft 33, the outer ring of the ball bearing 44b is elastically deformed, and the portion that is convex in the radial direction moves along the circumferential direction. Thus, the cam 44a is rotated by the drive of the motor 17, so that the flexspline 43 has a substantially elliptical shape, that is, the meshing position (meshing portion) between the flexspline 43 and each circular spline 41, 42 is the circular spline 41, 42. It is made to move along the circumferential direction.

  Then, by driving the wave gear mechanism 16 connected to the first shaft 14 and the second shaft 15 and the motor shaft 33 in this way, the transmission ratio between the steering wheel 2 and the steered wheels 11 ( The gear ratio) can be changed.

  Specifically, the rotation of the first shaft 14 accompanying the steering operation is transmitted from the stay circular spline 41 connected to the first shaft 14 to the drive circular spline 42 via the flex spline 43, and thereby to the second shaft 15. Is communicated. Further, the wave generator 44 is driven by the motor 17, and the elliptical shape of the flex spline 43, that is, the meshing portion with each of the circular splines 41, 42 rotates, so that the number of teeth between the circular splines 41, 42 is based. The difference in rotation is added to the rotation based on the steering operation and transmitted to the second shaft 15 as the rotation based on the motor drive. As a result, the rotation transmission ratio between the first shaft 14 and the second shaft 15, that is, the transmission ratio between the steering wheel 2 and the steered wheels 11 can be changed.

Further, the transmission ratio variable device 12 includes a lock mechanism (not shown) that temporarily fixes the rotational position of the motor shaft 33 (rotor 28) to the housing 21.
(Fixing structure of support member)
Next, a structure for fixing the support member 46 to the housing 21 in this embodiment will be described.

  As shown in FIG. 3, the second shaft 15 is coaxially connected to a drive circular spline 42 that is arranged so as to be coaxial with the motor shaft 33, and due to its structure, the axial center of the second shaft 15 ( The central axis L1 is provided so as to coincide with the axis L2 of the motor 17. Here, the motor 17 is accommodated in the housing 21 so as to be coaxial with the housing 21, but due to the dimensional accuracy of the motor 17 and the housing 21, the axis L <b> 2 of the motor 17 and the housing 21 are not necessarily limited. The axis L3 does not always match. Thus, when the axis L2 of the motor 17 and the axis L3 of the housing 21 do not coincide with each other, the housing 21 is arranged so that the axis L4 of the support member 46 coincides with the axis L3 of the housing 21 as in the prior art. On the other hand, if it is directly fixed, the second shaft 15 is supported in a state of being off-axis with respect to the bearing 47. 3 to 5, the deviation between the axis L3 of the housing 21 and the axis L2 (axis L1, L4) of the motor 17 is exaggerated for convenience of explanation.

  In consideration of this point, in the transmission ratio variable device 12 of the present embodiment, the support member 46 is configured to be attachable to the second shaft 15 with its axis L4 coincident with the axis L1 of the second shaft 15. ing. The transmission ratio variable device 12 maintains the relative position in the radial direction between the housing 21 and the support member 46 in a state where the axis L5 of the bearing 47 and the axis L1 of the second shaft 15 coincide with each other. A connecting member 51 for connecting the support member 46 and the housing 21 so as not to move relative to each other is provided.

  More specifically, the support member 46 includes a substantially cylindrical main body portion 52 and a substantially annular extending portion 53 that extends outward from the main body portion 52 in the radial direction. A bearing 47 is provided on the inner periphery of the main body 52 so as to be coaxial with the main body 52, and the second shaft 15 is rotatably supported by the bearing 47. In the present embodiment, the bearing 47 employs a cross roller bearing that is disposed between the inner ring and the outer ring so that the axes of adjacent rollers intersect. Further, a seal member 55 is provided on the output side (lower side in FIG. 3) of the bearing 47 in the main body 52 via an annular spacer 54.

  On the other hand, the connecting member 51 has a substantially cylindrical fixing portion 57 fixed to the housing 21, and a substantially annular shape that extends radially inward from the fixing portion 57 and sandwiches the extending portion 53 between the housing 21. The clamping part 58 is provided. A screw portion 61 is formed on the inner periphery of the fixing portion 57, and a screw portion 62 that is screwed to the screw portion 61 is formed on the outer periphery of the lower end portion 21 b of the housing 21. The connecting member 51 is fixed to the housing 21 by screwing the screw portion 61 of the fixing portion 57 to the screw portion 62 of the housing 21. Furthermore, in this embodiment, the outer periphery of the fixing portion 57 is caulked by applying a pressing force radially inward, so that the screw portions 61 and 62 are not loosened.

  The extending portion 53 has an outer diameter that is larger than the inner diameter of the lower end portion 21 b and smaller than the inner diameter of the fixing portion 57 by a predetermined value or more, and is arranged in a loosely fitted state in the fixing portion 57. Is formed. That is, the extending portion 53 is formed so as not to contact the inner peripheral surface of the fixing portion 57 and to be disposed in the fixing portion 57 in a state where no load is received from the inner peripheral surface. The predetermined value is the maximum value of the axial deviation between the support member 46 (bearing 47) and the housing 21 (second shaft 15) caused by the dimensional accuracy of the motor 17 and the housing 21. Accordingly, the support member 46 is configured to be attachable to the second shaft 15 with its axis L4 aligned with the axis L1 of the second shaft 15. The support member 46 is fixed so as not to move in the axial direction with respect to the housing 21 by the extension portion 53 being sandwiched between the lower end portion 21 b of the housing 21 and the sandwiching portion 58 of the connecting member 51. It has a configuration.

  A plurality (four in this embodiment) of recesses 64 are formed on the contact surface 63 that contacts the clamping portion 58 of the extension portion 53. The recesses 64 are formed in a circular cross section and are formed at equal angular intervals in the circumferential direction of the support member 46. Further, the abutment surface 63 and the abutment surface 65 that abuts on the extending portion 53 of the clamping portion 58 are mirror-finished as a surface treatment, and the friction coefficient of the abutment surfaces 63 and 65 is reduced. It is configured as follows. The clamping portion 58 receives a pressing force in the axial direction in a state where the support member 46 is attached to the housing 21 so that the axis L5 of the bearing 47 coincides with the axis L1 of the second shaft 15. A convex portion 66 that is caulked by being applied and engages with the concave portion 64 is formed. As described above, the convex portion 66 engages with the concave portion 64, whereby the support member 46 is fixed to the connecting member 51 so as not to be relatively movable in the circumferential direction and the radial direction. That is, the support member 46 is fixed to the housing 21 by the connecting member 51 so as not to move relative to the housing 21 in the circumferential direction and the radial direction. Accordingly, in the present embodiment, the concave portion 64 and the convex portion 66 constitute a regulating means.

  Note that an annular projecting portion 68 projecting toward the housing 21 is formed on the extending portion 53 of the present embodiment, and a disc spring 69 is interposed between the projecting portion 68 and the intermediate member 45. Has been. The outer diameter of the projecting portion 68 is larger than the inner diameter of the lower end portion 21b of the housing 21 so that the support member 46 can be attached to the second shaft 15 by aligning the axis L1, L4. It is formed to be smaller than a predetermined value and is formed so as to be loosely fitted in the housing 21.

Next, assembly of the transmission ratio variable device of this embodiment will be described.
As shown in FIG. 4, the motor 17 and the wave gear mechanism 16 are fixed in the housing 21, and the intermediate member 45 and the second shaft 15 are coupled to the drive circular spline 42 constituting the wave gear mechanism 16. The support member 46 is fitted onto the second shaft 15 such that the shaft center L5 of 47 (the axis L4 of the support member 46) coincides with the axis L1 of the second shaft 15. At that time, the position of the support member 46 follows the position of the second shaft 15 by rotating the second shaft 15 one or two times without fixing the motor shaft 33 by the lock mechanism. 46 axial center L4 and the axial center L1 of the 2nd shaft 15 correspond reliably. Subsequently, as shown in FIG. 5, the screw portion 61 of the fixing portion 57 is screwed into the screw portion 62 of the lower end portion 21 b, whereby the connecting member 51 is fixed to the housing 21.

  Here, since the extending portion 53 is formed so as to be loosely fitted in the fixing portion 57, even if the connecting member 51 is fixed to the housing 21, the connecting member 51 supports the support member 46. A radial load does not act, and the relative position in the radial direction between the housing 21 and the support member 46 is maintained. That is, the state where the axis L1 of the second shaft 15 and the axis L5 of the bearing 47 coincide with each other is maintained, and no load acts on the second shaft 15 from the bearing 47.

  After that, the clamping portion 58 is caulked to fix the support member 46 so as not to move relative to the housing 21, and the fixing portion 57 is caulked so that the screw portions 61 and 62 are not loosened. Then, the transmission ratio variable device 12 is assembled. The support member 46 is assembled so that the circumferential position of the concave portion 64 with respect to the second shaft 15 is a predetermined position, and the holding member 46 is clamped by caulking the vicinity of the predetermined position in the holding portion 58. A convex portion 66 that engages with the concave portion 64 is formed in the portion 58.

As described above, according to the present embodiment, the following operational effects can be achieved.
(1) The transmission ratio variable device 12 includes a wave gear mechanism 16 that transmits rotation to the second shaft 15 by adding rotation based on motor driving to rotation of the first shaft 14, and a cylinder that houses the wave gear mechanism 16 and the motor 17. The second shaft 15 is rotatably supported via a bearing 47 on an annular support member 46 provided on the housing 21. Further, the support member 46 is configured to be attachable to the second shaft 15 such that the axis L4 of the support member 46 coincides with the axis L1 of the second shaft 15. The support member 46 and the housing 21 are maintained while maintaining the relative position in the radial direction between the housing 21 and the support member 46 in a state where the axis L5 of the bearing 47 and the axis L1 of the second shaft 15 are aligned. Are connected to each other so as not to move relative to each other.

  According to the above configuration, the support member 46 and the housing 21 are connected in a state in which the relative position in the radial direction in the state where the axis L5 of the bearing 47 and the axis L1 of the second shaft 15 coincide with each other is maintained. The members 51 are connected so as not to move relative to each other. That is, the support member 46 is fixed to the housing 21 by the connecting member 51 in a state where the axis L5 of the bearing 47 and the axis L1 of the second shaft 15 are aligned. Therefore, even when the wave gear mechanism 16 and the motor 17 are accommodated in the housing 21 in a state where the axis L2 of the motor 17 and the axis L3 of the housing 21 do not coincide with each other, the second shaft 15 is supported by the bearing 47. In contrast, it is possible to prevent the shaft center L1 from being supported in a shifted state. Therefore, the meshing state of the wave gear mechanism 16 can be maintained satisfactorily, and vibration and noise associated with the operation can be reduced. Thereby, the steering apparatus 1 for vehicles excellent in silence can be provided.

  (2) The support member 46 includes a cylindrical main body 52 on which the bearing 47 is provided, and an extending portion 53 that extends radially outward from the main body 52. The connecting member 51 includes a cylindrical fixing portion 57 that is fixed to the housing 21, and a clamping portion 58 that extends radially inward from the fixing portion 57 and sandwiches the extending portion 53 between the housing 21. Equipped with. The extending portion 53 is formed so as to be loosely fitted in the fixed portion 57, and the convex portion 66 of the clamping portion 58 is engaged with the concave portion 64 of the extending portion 53, whereby the support member 46. The movement of the housing 21 is restricted in the radial direction and the circumferential direction. According to the said structure, since the connection member 51 consists of the cylindrical fixing | fixed part 57 and the clamping part 58, the same connection member 51 can be made into a simple structure.

  (3) When the convex portion 66 formed by plastically deforming the clamping portion 58 is engaged with the concave portion 64 of the extending portion 53, the movement of the support member 46 in the radial direction and the circumferential direction in the housing 21 is restricted. Therefore, the support member 46 can be fixed to the housing 21 so as not to be movable in the radial direction and the circumferential direction without increasing the number of parts. Further, since the convex portion 66 is formed in a state where the support member 46 is attached to the housing 21 so that the axis L5 of the bearing 47 coincides with the axis L1 of the second shaft 15, the connecting member 51 is provided. When the fixing portion 57 is screwed to the housing 21, the relative position of the support member 46 to the housing 21 can be suppressed from shifting. Therefore, the connecting member 51 can be configured to be fixed to the housing 21 by screwing the fixing portion 57 to the housing 21.

  (4) Since the connecting member 51 is fixed to the housing 21 by screwing the fixing portion 57 to the housing 21, the connecting member 51 can be easily fixed to the housing. it can.

  (5) The respective contact surfaces 63 and 65 are mirror-finished so that the contact surface 63 of the extending portion 53 and the contact surface 65 of the sandwiching portion 58 have a low friction coefficient. Therefore, for example, when the convex portion 66 is formed by caulking the clamping portion 58 or when the fixing portion 57 of the connecting member 51 is screwed to the housing 21, the connecting member 51 acts on the support member 46. The frictional force to be reduced is reduced, and the relative position of the support member 46 with respect to the housing 21 can be suppressed from shifting.

(6) Since a cross roller bearing is adopted as the bearing 47, the load in the radial direction and the thrust direction can be received by one bearing, and the apparatus can be downsized.
(Second Embodiment)
Hereinafter, a second embodiment in which the present invention is embodied in a vehicle steering apparatus including a so-called rack housing integrated type transmission ratio variable device in which a housing is fixed to a rack housing will be described with reference to the drawings. For convenience of explanation, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  As shown in FIG. 6, the transmission ratio variable device 71 of the present embodiment is provided on the pinion shaft 10 integrally with the rack housing 5. Specifically, the pinion shaft 10 includes an input shaft 72 connected to the intermediate shaft 9 (see FIG. 1) and an output shaft 73 meshed with the rack shaft 6. The transmission ratio variable device 71 includes a wave gear mechanism 75 as a differential mechanism that connects the input shaft 72 and the output shaft 73, and a motor 76 that drives the wave gear mechanism 75. As a result, the transmission ratio variable device 71 adds the rotation based on the drive of the motor 76 to the rotation of the input shaft 72 accompanying the steering operation and transmits the rotation to the output shaft 73, so that the steering wheel 2 and the steered wheels 11 are connected. The transmission ratio is made variable.

  More specifically, the transmission ratio variable device 71 includes a substantially cylindrical housing 81 fixed to the upper surface of the rack housing 5, and the housing 81 includes a lower housing 82 fixed to the upper portion of the rack housing 5, and The upper housing 83 is connected to the upper end of the lower housing 82. The wave gear mechanism 75 and the motor 76 are accommodated in the upper housing 83.

  More specifically, the output shaft 73 is rotatably supported through ball bearings 85 and 86 provided in the lower housing 82 with one end projecting into the upper housing 83. Further, a brushless motor having a hollow motor shaft 87 (rotor) is adopted as the motor 76 of the transmission ratio variable device 71. The motor 76 is provided so as not to rotate relative to the upper housing 83, which is a non-rotating part, by fixing the stator 89 to the inner periphery of the upper housing 83 via the motor housing 88. One end of the output shaft 73 protruding into the upper housing 83 is inserted into the motor shaft 87 so as to extend to the vicinity of the upper end portion 83a (the upper end portion in FIG. 6) of the upper housing 83. Has been. In the present embodiment, the output shaft 73 includes a first shaft member 91 connected to the wave gear mechanism 75 and a second shaft member 92 formed with pinion teeth that mesh with the rack shaft 6. It is formed by connecting via a torsion bar 93.

  An input shaft 72 is connected to the stay circular spline 94 disposed on the motor 76 side of the wave gear mechanism 75, and each drive circular spline 95 disposed on the upper end portion 83 a side of the upper housing 83 has each circular. One end of the output shaft 73 that protrudes toward the upper end 83a side in the axial direction from the splines 94 and 95 is connected. In addition, a cylindrical flex spline 96 is disposed inside each of the circular splines 94 and 95, and a wave generator 97 that rotates a meshing portion of the flex spline 96 by driving a motor is disposed.

  Specifically, as shown in FIG. 7, the output shaft 73 includes a cylindrical portion 98 a fitted to the outer periphery of the output shaft 73, and a drive circular spline 95 extending radially outward from the outer periphery. It is connected to the drive circular spline 95 via an intermediate member 98 composed of a flange portion 98b fitted to the inner periphery. In addition, a cylindrical portion 72 a having an inner diameter larger than the outer diameter of each of the circular splines 94 and 95 is formed at the inner end of the input shaft 72. The input shaft 72 is a mode in which the wave gear mechanism 75 and the intermediate member 98 are accommodated in the cylindrical portion 72 a, and the inner circumference thereof is press-fitted and fitted to the outer circumference of the stay circular spline 94. A spline 94 is connected.

  The input shaft 72 is rotatably supported via a bearing 47 with respect to an annular support member 46 provided at the upper end 83 a of the upper housing 83. The support member 46 is connected to the upper housing in a state where the shaft center L5 of the bearing 47 (the shaft center L4 of the support member 46) coincides with the shaft center L6 of the input shaft 72 by the connecting member 51, as in the first embodiment. It is fixed so that it cannot move relative to 83. A screw part 99 corresponding to the screw part 61 formed in the fixing part 57 of the connecting member 51 is formed on the outer periphery of the upper end part 83 a of the upper housing 83. Thereby, even when the wave gear mechanism 75 and the motor 76 are accommodated in the upper housing 83 in a state where the shaft center L7 of the motor 76 and the shaft center L8 of the upper housing 83 do not coincide with each other, the input shaft 72 is The bearing 47 is prevented from being supported in a state in which the axis L6 is displaced.

As described above, according to the present embodiment, the same operational effects as the operational effects of the first embodiment can be achieved.
In addition, the said embodiment can also be implemented in the following aspects which changed this suitably.

In each of the above embodiments, a cross roller bearing is used as the bearing 47. However, the present invention is not limited to this, and other bearings such as a ball bearing and a needle bearing may be used.
In each of the above embodiments, the annular protrusion 68 that protrudes toward the housing 21 is formed on the extension 53. However, the present invention is not limited to this, and the protrusion 68 may not be formed on the extension 53. .

  In each of the above-described embodiments, the surface of the contact surfaces 63 and 65 is mirror-finished so that the friction coefficient of the contact surfaces 63 and 65 is reduced. The friction coefficient may be lowered by forming a resin layer made of fluororesin or the like having low friction characteristics. Moreover, it is not necessary to perform the surface treatment for making each contact surface 63 and 65 have a low friction coefficient.

  In each of the above embodiments, the connecting member 51 is fixed to the housing 21 or the upper housing 83 by fixing the fixing portion 57 to the housing 21 or the upper housing 83. However, the present invention is not limited to this. For example, the connecting member 51 may be fixed to the housing 21 or the upper housing 83 by press-fitting the housing 21 or the upper housing 83 into the fixing portion 57.

  In each of the above embodiments, the convex portion 66 formed by plastically deforming the clamping portion 58 is engaged with the concave portion 64 of the extending portion 53, whereby the support member 46 is moved in the radial direction and the circumferential direction. Be regulated. However, the present invention is not limited to this, and the contact surfaces 63 and 65 are configured to have a high friction coefficient, and the contact surfaces 63 and 65 are frictionally engaged with each other, whereby the radial direction and the circumferential direction of the support member 46 are provided. The movement to may be regulated. In this case, the contact means 63 and 65 constitute a restricting means. Further, for example, by applying an adhesive as a regulating means to the contact surface 63, the movement of the support member 46 may be regulated in the radial direction and the circumferential direction. In these cases, it is preferable that the connecting member 51 is fixed to the housing 21 or the upper housing 83 by, for example, press fitting the housing 21 or the upper housing 83 into the fixing portion 57.

  In each of the above embodiments, the connecting member 51 is configured by the substantially cylindrical fixing portion 57 and the sandwiching portion 58. However, the connecting member 51 is not limited to this, and the support member 46 and the housing 21 or the upper housing 83 cannot move relative to each other. Any configuration may be used as long as it can be connected to the.

  In each of the above-described embodiments, the wave gear mechanisms 16 and 75 are so-called ring-shaped members having a pair of cylindrical splines that are coaxially arranged side by side. However, a single circular spline and a bottomed cylindrical shape are used. You may apply to what is called a cup type which takes out the rotation difference based on the number-of-teeth difference with the formed flexspline as a reduction ratio. Moreover, you may apply to what uses a planetary gear mechanism as a differential mechanism.

  In the second embodiment, the present invention is embodied in a vehicle steering apparatus provided with a so-called rack housing integrated type transmission ratio variable device. However, the present invention is not limited to this, and a housing-fixed type may be embodied, for example, as a so-called column-type transmission ratio variable device or the like that is fixed to a non-rotating part other than the rack housing.

  In each of the embodiments described above, the present invention is embodied in the transmission ratio variable devices 12 and 71 of the vehicle steering apparatus 1, but may be applied to a transmission ratio variable device used for other purposes.

  DESCRIPTION OF SYMBOLS 1 ... Vehicle steering device, 12, 71 ... Transmission ratio variable device, 14 ... 1st shaft, 15 ... 2nd shaft, 16, 75 ... Wave gear mechanism, 17, 76 ... Motor, 21, 81 ... Housing, 46 ... Support member, 47 ... bearing, 51 ... connecting member, 52 ... main body part, 53 ... extension part, 57 ... fixing part, 58 ... clamping part, 61, 62, 99 ... screw part, 63, 65 ... contact surface, 64 ... concave portion, 66 ... convex portion, 72 ... input shaft, 73 ... output shaft, L1-L8 ... axial center.

Claims (6)

A differential mechanism that adds rotation based on motor driving to rotation of the input shaft and transmits the rotation to the output shaft; and a cylindrical housing that houses the differential mechanism and the motor, and includes any one of the input shaft and the output shaft. One of them is a transmission ratio variable device that is rotatably supported by a ring-shaped support member provided in the housing via a bearing,
A connecting member for connecting the support member to the housing;
The support member can be attached to any one of the input shaft and the output shaft such that the shaft center of the bearing coincides with the one shaft center,
The connecting member holds the support member and the housing relative to each other while maintaining the relative position in the radial direction between the support member and the housing in a state in which the shaft center of the bearing and the one shaft center coincide with each other. A transmission ratio variable device characterized by being connected so as to be immovable. The transmission ratio variable device according to claim 1,
The support member includes a cylindrical main body provided with the bearing, and an extending part extending radially outward from the main body,
The connecting member includes a cylindrical fixing part fixed to the housing, and a clamping part that extends radially inward from the fixing part and sandwiches the extension part between the housing and the housing.
The extension portion is formed so as to be loosely fitted in the fixed portion,
A transmission ratio variable device, characterized in that a regulating means for regulating movement of the support member in the radial direction and circumferential direction is provided. The transmission ratio variable device according to claim 2,
The regulating means is
A recess formed on the abutting surface that abuts on the clamping part of the extension part;
In a state where the support member is provided to the housing so that the shaft center of the bearing coincides with the one shaft center, the holding portion is formed by plastic deformation so as to engage with the recess. Consists of convex parts,
The transmission ratio variable device according to claim 1, wherein movement of the support member in a radial direction and a circumferential direction is restricted by engaging the convex portion with the concave portion. The transmission ratio variable device according to claim 3,
The transmission ratio variable device according to claim 1, wherein the contact surface of the extension portion and the contact surface of the holding portion that contacts the extension portion are surface-treated so as to have a low friction coefficient. In the transmission ratio variable device according to any one of claims 1 to 4,
The transmission ratio variable device, wherein the bearing is a cross roller bearing.   A vehicle steering system comprising the transmission ratio variable device according to any one of claims 1 to 5.

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