JP6464719B2 - Torque transmission joint and electric assist device - Google Patents

Description

  The torque transmission joint according to the present invention is incorporated in various mechanical devices and used to transmit torque between the drive shaft and the driven shaft. The electric assist device of the present invention is incorporated in a steering device of an automobile and uses an electric motor as an auxiliary power source to reduce the force required for the driver to operate the steering wheel.

  Power steering devices are widely used as devices for reducing the force required for the driver to operate the steering wheel when giving a steering angle to the steered wheels (usually the front wheels except for special vehicles such as forklifts). It is used. In addition, an electric power steering apparatus that uses an electric motor as an auxiliary power source in such a power steering apparatus has begun to spread in recent years. Such an electric power steering apparatus has a steering shaft rotated by an operation of a steering wheel or a member (pinion shaft or rack shaft constituting a steering gear unit) displaced with the rotation of the steering shaft. Auxiliary power is applied through a speed reducer. In general, a worm reducer is used as the reducer. In the case of an electric power steering apparatus using a worm speed reducer, a worm that is rotationally driven by the electric motor and a worm wheel that rotates together with a rotating shaft that is an output portion of the worm speed reducer are meshed, and the electric motor The auxiliary power can be transmitted to the rotating shaft. However, in the case of a worm reducer, if no measures are taken, it is called a rattling sound when changing the rotation direction of the rotating shaft based on the backlash existing in the meshing portion of the worm and the worm wheel. Unpleasant noise may occur.

  Conventionally, it has been considered to elastically press the worm toward the worm wheel by an elastic member such as a spring as a structure capable of suppressing the generation of such rattling noise. 9 to 11 show an example of the electric power steering device described in Patent Document 1. FIG. The electric power steering apparatus includes a steering shaft 2 with a steering wheel 1 supported and fixed at a rear end portion, a steering column 3 with the steering shaft 2 rotatably supported on the inner diameter side thereof, and the steering shaft 2. And an electric assist device 4 for applying auxiliary power. Among these, the electric assist device 4 includes an electric motor 5, a housing 6, and a worm reduction gear 7. The worm speed reducer 7 is housed in the housing 6 and is applied to the steering shaft 2 while increasing the torque of the output shaft 8 of the electric motor 5, and includes a worm wheel 9 and a worm 10 And have. The worm wheel 9 is supported and fixed concentrically with the steering shaft 2 at a front end portion of the steering shaft 2 rotatably supported in the housing 6. The worm 10 is provided with a worm tooth 11 that meshes with the worm wheel 9 at an intermediate portion in the axial direction, and both ends in the axial direction are attached to the housing 6 by a pair of rolling bearings 12a and 12b such as deep groove ball bearings. It is supported and fixed so that it can rotate. Further, a pressing piece 13 is externally fitted to a portion protruding from one of the rolling bearings 12 a and 12 b (right side in FIG. 10) of the rolling bearing 12 a at the tip of the worm 10. A coil spring 14, which is an elastic member, is provided between the housing 6. The worm teeth 11 provided on the worm 10 are pressed toward the worm wheel 9 through the pressing piece 13 by the elasticity of the coil spring 14. With such a configuration, backlash between the worm teeth 11 and the worm wheel 9 is suppressed, and generation of the rattling noise is suppressed.

  In the case of the conventional structure as described above, it is possible to suppress the occurrence of the rattling noise at the meshing portion between the worm tooth 11 and the worm wheel 9, but the tip of the output shaft 8 of the electric motor 5 (see FIG. 10 at the right end) and the base end of the worm 10 (left end in FIG. 10) cannot be suppressed. This point will be described below. In the case of the structure shown in the figure, a spline hole 15 is formed in the base end portion of the worm 10 in order to couple the tip end portion of the output shaft 8 of the electric motor 5 and the base end portion of the worm 10 so that torque can be transmitted. The worm 10 is formed so as to open to the base end face. On the other hand, a spline shaft portion 16 is formed at the distal end portion of the output shaft 8. The spline shaft portion 16 and the spline hole 15 are spline-engaged so that the output shaft 8 and the worm 10 are coupled so that torque can be transmitted.

  By the way, if the spline shaft portion 16 and the spline hole 15 are in spline engagement with no circumferential clearance (without backlash), the distal end portion of the output shaft 8 and the proximal end portion of the worm 10 No noise is generated at the connecting portion (spline engaging portion). However, in the actual case, a backlash exists in the spline engaging portion. In particular, as shown in FIG. 10 described above, a structure in which backlash between the worm teeth 11 and the worm wheel 9 can be suppressed by elastically pressing the worm teeth 11 toward the worm wheel 9. In this case, since it is necessary to swing and displace the worm 10, the backlash of the spline engaging portion cannot be completely eliminated, and it is difficult to prevent the generation of abnormal noise.

  In Patent Document 2, the tip end portion of the output shaft of the electric motor and the base end portion of the worm are coupled via a torque transmission joint (shaft joint) provided with an elastic material such as rubber. A structure is described in which the output shaft and the worm are prevented from coming into direct contact with each other, and the generation of abnormal noise as described above can be effectively prevented. In the case of such a structure described in Patent Document 2, in order to improve the responsiveness of the electric assist device (rotational synchronization between the output shaft and the worm), the elastic coefficient of the elastic material is increased. Thus, it is necessary to increase the elasticity of the elastic material. However, when the elasticity of the elastic material increases, the worm becomes difficult to swing and displace.

  On the other hand, in Patent Document 3, the worm and the output shaft of the electric motor are made of a plate material such as spring steel, and a flat base (base) is extended from the base to the base end of the worm. A pair of driven side arms (first arm) to be connected, and a pair of driving side arms extending from the base to the opposite side of the both driven side arms and connected to the output shaft A structure is described that is coupled via a torque transmission joint (connecting member) composed of a portion (second arm). In the case of such a structure described in Patent Literature 3, the rigidity of the torque transmission joint with respect to the rotation direction of the output shaft of the worm and the electric motor can be increased, and the responsiveness of the electric assist device is improved. Can be. On the other hand, by reducing the rigidity of the torque transmission joint in the radial direction of the output shaft of the worm and the electric motor, the worm can be swung. However, in the case of the structure described in Patent Document 3, the worm and the electric motor are connected to each other by a pair of driven side arm portions and driving side arm portions that extend in opposite directions with respect to the axial direction. Since the output shaft is connected, the axial dimension of the connecting portion between the worm and the output shaft of the electric motor becomes longer. As a result, there is a possibility that the overall size of the worm speed reducer is increased, or the deviation (swing) between the central axis of the worm and the central axis of the output shaft of the electric motor due to the oscillating displacement of the worm becomes too large. . Further, in the case of the structure described in Patent Document 3, the both driven side arm portions and the both driven side arm portions are provided in a state where their phases are shifted by 90 degrees. The rigidity related to the direction of the force applied to the torque transmission joint in accordance with the swing displacement varies depending on the position (phase) in the rotational direction of the torque transmission joint (worm). Therefore, the reaction force applied to the worm from the torque transmission joint may change depending on the position (phase) in the rotational direction of the torque transmission joint (worm).

JP 2004-306898 A Japanese Patent Laid-Open No. 2004-203154 JP 2012-201173 A

  In view of the circumstances as described above, the present invention can smoothly transmit torque between the drive shaft and the driven shaft, and can ensure rotational synchronization between the drive shaft and the driven shaft. Furthermore, a torque transmission joint structure capable of making the reaction force applied to the driven shaft almost constant regardless of the position of the driven shaft in the rotational direction is realized while suppressing an increase in axial dimension. It is aimed at things.

Torque transmitting joint of the torque-transmitting joint and electric assist device of the present invention is to transmit torque between the ends of the drive shaft and a driven shaft arranged in series with each other in the axial direction A drive-side transmission member that is supported on the end of the drive shaft concentrically with the drive shaft and is formed in a substantially disc shape by a metal plate having elasticity, such as spring steel, and an end of the driven shaft. And a driven-side transmission member formed in a substantially disc shape by a metal plate having elasticity such as spring steel, which is supported concentrically with the driven shaft.
At least one of the drive-side transmission member and the driven-side transmission member is elastically deformable in the axial direction and the radial direction over the entire circumference (at the central portion and the outer portion). An elastically deformable portion is provided that has lower rigidity in the axial direction and the radial direction than the peripheral portion.
Drive-side engagement pieces are provided at a plurality of locations in the circumferential direction of the outer peripheral edge of the drive-side transmission member.
Driven side engagement pieces are provided at a plurality of locations in the circumferential direction of the outer peripheral edge of the driven side transmission member.
The drive-side engagement pieces and the driven-side engagement pieces are alternately arranged in the circumferential direction (the drive-side engagement pieces are located between adjacent driven-side engagement pieces. And the driven side engaging piece is engaged with the driving side notched part existing between adjacent driving side engaging pieces). The torque can be transmitted between the drive side transmission member and the driven side transmission member.
Further, in a state where the elastic deformation portion is incorporated between the drive shaft and the driven shaft, the drive shaft and the driven shaft are given elasticity in directions away from each other in the axial direction.

  When the torque transmission joint of the present invention as described above is implemented, the drive-side engagement pieces and the driven-side engagement pieces are engaged with no gap (without backlash) in the circumferential direction. It is preferable that In other words, each driving side engaging piece and each driven side notch are engaged without a gap in the circumferential direction (without backlash), and each driven side engaging piece and It is preferable that each drive-side notch is engaged with no gap in the circumferential direction.

Further, when performing the torque-transmitting joint such present invention described above, for example, the pre-Symbol elastically deformable portion, can be a radially peaks and troughs bellows portion is continuously alternately.

The electric assist device of the present invention includes an electric motor, a housing, and a worm reduction gear.
Of these, the housing is supported by a fixed portion and does not rotate.
The worm speed reducer is housed in the housing and increases the torque of the output shaft of the electric motor while rotating the steering shaft supported by the rear end portion of the steering shaft or rotating the steering shaft. It transmits to the member which moves with it. Such a worm speed reducer is provided with a worm wheel rotatably supported in the housing and a worm tooth at an axially intermediate portion, and the worm gear meshes with the worm wheel in the housing. And a worm supported rotatably.
The output shaft of the electric motor and the worm are connected to each other by a torque transmission joint so that torque can be transmitted.
Particularly in the electric assist device of the present invention, the torque transmission joint is the torque transmission joint of the present invention as described above. In this case, the output shaft of the electric motor corresponds to the drive shaft, and the worm corresponds to the driven shaft.
When implementing the electric assist device of the present invention as described above, preferably, the tip of the worm (the end opposite to the side coupled to the output shaft of the electric motor via a torque transmission joint) A preload applying mechanism that elastically presses the worm teeth toward the worm wheel can be provided between the housing and the housing.

According to the torque transmission joint of the present invention as described above, torque can be smoothly transmitted between the drive shaft and the driven shaft, and the rotational synchronization between the drive shaft and the driven shaft can be improved. Furthermore, it is possible to realize a structure capable of making the reaction force applied to the driven shaft substantially constant regardless of the position of the driven shaft in the rotational direction, while suppressing an increase in axial dimension. .
That is, when the driven shaft tends to become inconsistent due to rocking displacement with respect to the driving shaft, or due to the eccentricity of the central axis of the driving shaft and the central axis of the driven shaft, An elastic deformation portion provided on at least one of the driving side transmission member and the driven side transmission member is elastically deformed in the axial direction or the radial direction, so that the oscillating displacement and the driving shaft Deviation (bending) between the central axes of the driven shafts is allowed. Further, in the case of the present invention, the elastically deforming portion is provided over the entire circumference in the radial intermediate portion of the at least one transmission member. Accordingly, the rigidity of the torque transmission joint with respect to the direction of swinging displacement of the driven shaft is substantially uniform (predetermined range) regardless of the rotational position (phase) of the torque transmission joint (driven shaft). Inside). Therefore, the reaction force applied to the driven shaft from the torque transmission joint can be made constant (or almost constant) regardless of the position (phase) in the rotational direction of the driven shaft and the torque transmission joint. . As a result, torque transmission between the drive shaft and the driven shaft can be performed smoothly (with transmission loss suppressed).
Further, the rotational torque of the drive shaft is provided at the circumferential side edge of the drive side engaging piece provided at the outer peripheral edge portion of the drive side transmission member and at the outer peripheral edge portion of the driven side transmission member. It is transmitted to the driven shaft through a contact portion with the circumferential side edge of the driven side engaging piece. If the rigidity in the circumferential direction between each of the driving side engaging pieces and each of the driven side engaging pieces is sufficiently increased, the rotational synchronization between the driving shaft and the driven shaft can be improved.
In addition, the torque transmission joint of the present invention is configured by combining a substantially disk-shaped drive side transmission member and a driven side transmission member, and therefore, compared with the structure described in Patent Document 3 described above. The axial dimension of the coupling portion between the drive shaft and the driven shaft can be easily kept short. As a result, the overall size of the worm reduction gear can be reduced.

Sectional drawing which shows one example of embodiment of this invention. Sectional drawing which takes out and shows the coupling for torque transmission. Sectional drawing which takes out a transmission member and shows with a shaft and a volt | bolt. The front view which shows the state which took out the transmission member and was seen from the right side of FIG. The rear view which takes out the transmission member and shows the state seen from the left of FIG. Sectional drawing which shows a transmission member in a free state. 1 is a partially cut side view showing an example of a rack assist type electric power steering device in which the electric assist device of the present invention can be incorporated. 1 is a partially cut side view showing an example of a pinion assist type electric power steering device in which the electric assist device of the present invention can be incorporated. The partially cut side view which shows an example of the conventional structure of a column-assist type electric power steering device. The expanded XX sectional view of Drawing 9 showing an example of the conventional structure of an electric assistant device. YY sectional drawing of FIG.

  1 to 6 show an example of an embodiment of the present invention. The electric assist device 4a of this example is used by being incorporated in a column assist type electric power steering device as shown in FIG. 9, for example, and includes an electric motor 5a, a housing 6a, and a worm speed reduction device. The machine 7a and the torque transmission joint 17 are provided. Of these, the worm speed reducer 7a is housed in the housing 6a and is applied to the steering shaft 2 (see FIG. 9) while increasing the torque of the output shaft 8a of the electric motor 5a. It has a wheel 9 and a worm 10a. The worm wheel 9 is supported and fixed concentrically with the steering shaft 2 at a front end portion of the steering shaft 2 rotatably supported in the housing 6a. The worm 10a is provided with a worm tooth 11 that meshes with the worm wheel 9 at an axially intermediate portion, and both ends in the axial direction are rotatably supported and fixed to the housing 6a by a pair of rolling bearings 12a and 12b. ing. Further, a pressing piece 13 is externally fitted to a portion projecting from one of the rolling bearings 12a and 12b (left side in FIG. 1) of the rolling bearing 12a at the tip of the worm 10a. A coil spring 14 is provided between the housing 6a. The worm teeth 11 provided on the worm 10 a are pressed toward the worm wheel 9 through the pressing piece 13 by the elasticity of the coil spring 14. With such a configuration, backlash between the worm teeth 11 and the worm wheel 9 is suppressed, and generation of the rattling noise is suppressed.

  In the case of this example, the distal end portion (left end portion in FIG. 1) of the output shaft 8a of the electric motor 5a and the proximal end portion (right end portion in FIG. 1) of the worm 10a are connected via the torque transmission joint 17. Coupled to allow torque transmission. The torque transmission joint 17 includes a transmission member 18a that is a drive-side transmission member described in claims, and a transmission member 18b that is a driven-side transmission member. These transmission members 18a and 18b have the same shape and size as each other, and are reversed in the direction in the axial direction and slightly shifted in the phase in the circumferential direction (by the pitch of engagement pieces 24a and 24b described later). It is combined in the state. Each of the transmission members 18a and 18b is formed into a substantially disk shape by punching and bending a metal plate having elasticity such as a spring steel plate by press working. Bolts 19a and 19b for supporting and fixing the two transmission members 18a and 18b to the distal end portion of the output shaft 8a and the proximal end portion of the worm 10a are inserted through the central portions in the radial direction of the transmission members 18a and 18b. Through holes 20a and 20b are provided respectively. That is, the transmission members 18a and 18b are respectively connected to the bolts 19a and 19b inserted into the through holes 20a and 20b by screw holes 21a and 19b formed in the distal end surface of the output shaft 8a and the proximal end surface of the worm 10a. By being screwed into 21b and further tightened, it is supported and fixed to the output shaft 8a and the worm 10a, respectively. Further, among the opposite side surfaces of the transmission members 18a and 18b, the circumferential portions of the parts surrounding the through holes 20a and 20b are equally spaced at a plurality of locations (four locations in the illustrated example). Projections 22a and 22b projecting toward the distal end surface of the output shaft 8a and the proximal end surface of the worm 10a are formed in a state of extending in the radial direction. On the other hand, the locking grooves 31a and 31b are extended in the radial direction at a plurality of circumferentially equally spaced locations (four locations in this example) on the distal end surface of the output shaft 8a and the proximal end surface of the worm 10a. Is formed. When the transmission members 18a and 18b are supported and fixed to the output shaft 8a and the worm 10a, the projections 22a and 22b, the distal end surface of the output shaft 8a and the proximal end surface of the worm 10a. The engaging grooves 31a and 31b formed on the concave and convex portions are engaged with each other.

Further, in the radially intermediate portion of the transmission members 18a and 18b, the ridges and troughs are formed in the radial direction over the entire circumference in the radially outer portion of the portion where the projections 22a and 22b are formed. And bellows portions 23a and 23b, which are alternately and continuously formed, are formed. As shown in FIG. 6, these bellows portions 23a and 23b are in a free state before the transmission members 18a and 18b are assembled between the distal end portion of the output shaft 8a and the proximal end portion of the worm 10a. Inclined in a direction approaching each other as it goes outward in the radial direction. That is, an imaginary plane α ₀ (see FIG. 6) passing through the central portion (center line) of the peak portion and the valley portion of the bellows portion 23a (23b) in the free state has a partial conical surface shape. . Note that the number, height (depth), pitch, and the like of the ridges and valleys constituting the bellows portion 23a (23b) are not limited to the configuration of this example. Furthermore, engagement pieces 24a and 24b are formed at a plurality of circumferential positions (10 in the illustrated example) on the outer peripheral edge of the transmission members 18a and 18b, respectively. Each of the engagement pieces 24a and 24b is inclined between the transmission members 18a and 18b so as to approach each other toward the outer side in the radial direction. In addition, notches 25a and 25b are formed in portions between the engaging pieces 24a and 24b adjacent in the circumferential direction, respectively. Each of these notches 25a, the width _{W 25} in the circumferential direction of 25b, the respective engaging pieces 24a, or equal to the width _{W 24} in the circumferential direction of 24b, is slightly smaller than the width _{W 24} (W ₂₅ ≦ W ₂₄ ). With such a configuration, rigidity in the circumferential direction of each of the engagement pieces 24a and 24b is ensured.

In the case of this example, among the transmission members 18a and 18b, the engagement pieces 24a and 24a formed on one transmission member 18a supported and fixed to the tip of the output shaft 8a are connected to the worm 10a. The other transmission member is engaged with the notches 25b and 25b formed on the other transmission member 18b supported and fixed to the base end portion without any gap in the circumferential direction (without backlash). The respective engagement pieces 24b, 24b formed on 18b are engaged with the respective notches 25a, 25a formed on the one transmission member 18a without any clearance in the circumferential direction. Further, both the transmission members 18a and 18b are assembled between the distal end portion of the output shaft 8a and the proximal end portion of the worm 10a, and the both bellows portions 23a and 23b are arranged in the axial direction and the radial direction. An imaginary plane α (see FIG. 2) that is elastically deformed (crushed) and passes through the central part of the crests and troughs of both bellows parts 23a, 23b is formed on the central axis of both transmission members 18a, 18b. It is almost parallel to the orthogonal plane. Therefore, in a state in which both the transmission members 18a and 18b are assembled between the distal end portion of the output shaft 8a and the proximal end portion of the worm 10a, the output shaft 8a and the worm 10a are connected to the both transmission members. 18a and 18b are elastically pressed in directions away from each other with respect to the axial direction.

According to the electric assist device 4a of this example as described above, torque can be smoothly transmitted between the output shaft 8a of the electric motor 5a and the worm 10a, and the response of the electric assist device 4a. It is possible to realize a structure that can secure the property while suppressing an increase in the axial dimension.
That is, when the worm 10a is oscillated and displaced, or when the center axis of the output shaft 8a and the center axis of the worm 10a tend to become inconsistent, the transmission members 18a, 18b The bellows portions 23a and 23b provided at the intermediate portion in the radial direction are elastically deformed in the axial direction and the radial direction, so that the oscillating displacement of the worm 10a and the shift between the output shaft 8a and the central axis of the worm 10a are made. (Dripping) is allowed. Further, in the case of this example, the bellows portions 23a and 23b are provided over the entire circumference in the radial direction intermediate portions of the transmission members 18a and 18b, and the engagement pieces 24a and 24b are circumferential. It is provided at equal intervals with respect to the direction. Therefore, the rigidity of the torque transmission joint 17 with respect to the swing displacement direction of the worm 10a is substantially uniform (predetermined range) regardless of the position (phase) in the rotational direction of the torque transmission joint 17 (worm 10a). Inside). Therefore, the reaction force applied to the worm 10a from the torque transmission joint 17 constituted by the transmission members 18a and 18b is constant regardless of the rotational position (phase) of the worm 10a and the torque transmission joint 17. (Or almost constant). As a result, the torque transmitted from the output shaft 8a to the worm 10a is suppressed, and torque transmission between the output shaft 8a and the worm 10a is performed smoothly (with reduced transmission loss). Can do.

Further, the rotational torque of the output shaft 8a is applied to the worm 10a through the contact portions between the circumferential edges of the engagement pieces 24a and 24b provided on the outer peripheral edges of the transmission members 18a and 18b, respectively. Communicated. In the case of this example, the rigidity in the circumferential direction of each of the engagement pieces 24a and 24b is sufficiently secured, so that the rotation synchronism between the output shaft 8a and the worm 10a can be improved (this output shaft 8a The delay of the rotation of the worm 10a relative to the rotation of the electric assist device 4a can be reduced), and the response of the electric assist device 4a can be improved.
Further, the width W _{25 in} the circumferential direction of the notches 25a and 25b is equal to or slightly smaller than the width W _{24 in} the circumferential direction of the engagement pieces 24a and 24b (W ₂₅ ≦ W ₂₄ ) The engaging pieces 24a, 24b and the notches 25a, 25b are engaged with each other without any gap in the circumferential direction (without backlash). For this reason, generation | occurrence | production of abnormal noise can be suppressed in the engaging part of each said engagement piece 24a, 24b and each said notch part 25a, 25b.
Further, in the case of this example, the transmission members 18a and 18b are provided with the projections 22a and 22b, and are formed on the projections 22a and 22b, the distal end surface of the output shaft 8a, and the proximal end surface of the worm 10a. Further, the engaging grooves 31a and 31b are engaged with the concave and convex portions. For this reason, the engagement strength of these engaging portions can be increased, and it is possible to prevent a torque transmission loss from occurring between the transmission members 18a and 18b, the output shaft 8a and the worm 10a.

Further, the torque transmission joint 17 constituting the electric assist device 4a of the present example is provided with bellows portions 23a and 23b for allowing the worm 10a to swing and displace at the radially intermediate portion, and at the outer peripheral edge portion. The engagement pieces 24a and 24b and the cutout portions 25a and 25b for torque transmission are provided, and the whole is formed by combining a pair of transmission members 18a and 18b which are substantially disk-shaped. . For this reason, the driving shaft and the driven shaft described in the above-mentioned Patent Document 3 are formed by a pair of the driving side arm portion and the driven side arm portion respectively extending in opposite directions with respect to the axial direction. Compared with the connected structure, the axial dimension of the coupling portion between the output shaft 8a and the worm 10a can be kept short. Accordingly, the worm speed reducer 7a can be easily reduced in size, and the deviation between the central axis of the output shaft 8a and the central axis of the worm 10a due to the swinging displacement of the worm 10a can be suppressed to be small.
When the electric assist device 4a of this example is implemented, only one of the transmission members 18a and 18b is provided with a bellows portion that can be elastically deformed in the axial direction and the radial direction. You can also do things. That is, one transmission member and the other transmission member can be formed in different shapes. Moreover, the elastic deformation part provided in a transmission member is not limited to a bellows part like this example.

The electric assist device 4a of this example is not limited to the column assist type electric power steering device as shown in FIG. 9, but is a rack assist type electric power steering device as shown in FIG. It can be incorporated into a pinion assist type electric power steering device.
In the case of the rack assist type electric power steering apparatus shown in FIG. 7, universal joints 28 and 28 and an intermediate shaft 29 are provided at the front end portion of the steering shaft 2a at a part of the rack 27 constituting the steering gear unit 26 in the axial direction. A rotating shaft (not shown) is disposed in a portion that is disengaged from the pinion shaft 30 that is connected via the pinion shaft 30. And the worm wheel 9 (refer FIG. 1) which comprises the electric assist apparatus 4a is supported and fixed to this rotating shaft.
Further, in the case of the pinion assist type electric power steering apparatus shown in FIG. 8, a pinion that constitutes a steering gear unit 26a and is connected to the front end portion of the steering shaft 2a via universal joints 28 and 28 and an intermediate shaft 29. The worm wheel 9 constituting the electric assist device 4a is supported and fixed to the shaft 30a.

DESCRIPTION OF SYMBOLS 1 Steering wheel 2, 2a Steering shaft 3 Steering column 4, 4a Electric assist device 5, 5a Electric motor 6, 6a Housing 7, 7a Worm speed reducer 8, 8a Output shaft 9 Worm wheel 10, 10a Worm 11 Worm tooth 12a, 12b Rolling bearing 13 Pressing piece 14 Coil spring 15 Spline hole 16 Spline shaft part 17 Torque transmission joint 18a, 18b Transmission member 19a, 19b Bolt 20a, 20b Through hole 21a, 21b Screw hole 22a, 22b Protrusion 23a, 23b Bellows part 24a, 24b engagement piece 25a, 25b notch 26, 26a steering gear unit 27 rack 28 universal joint 29 intermediate shaft 30, 30a pinion shaft 31a, 31b locking groove

Claims (3)

A torque transmission joint that transmits torque between ends of a drive shaft and a driven shaft that are arranged in series with each other in the axial direction,
A drive-side transmission member made of a metal plate supported concentrically with the drive shaft at the end of the drive shaft, and a driven plate made of metal plate supported concentrically with the driven shaft at the end of the driven shaft. A side transmission member,
An elastically deformable portion that is elastically deformable in the axial direction and the radial direction over the entire circumference is provided at the radial intermediate portion of at least one of the driving side transmission member and the driven side transmission member. And
Drive-side engagement pieces are provided at a plurality of locations in the circumferential direction of the outer peripheral edge of the drive-side transmission member,
Driven side engagement pieces are provided at a plurality of locations in the circumferential direction of the outer peripheral edge of the driven side transmission member,
The drive-side engagement pieces and the driven-side engagement pieces are alternately arranged in the circumferential direction, so that torque between the drive-side transmission member and the driven-side transmission member can be reduced. Communication is possible ,
Torque transmission, in which the elastically deforming portion is incorporated between the drive shaft and the driven shaft, and gives elasticity to the drive shaft and the driven shaft in directions away from each other in the axial direction. Fittings. The joint for torque transmission according to claim 1, wherein the elastically deformable portion is a bellows portion in which a ridge portion and a valley portion are alternately continued in a radial direction. An electric motor;
A housing that is supported by a fixed part and does not rotate;
A steering shaft that is housed in this housing and increases the torque of the output shaft of the electric motor, and is rotated by a steering wheel supported and fixed at the rear end, or a member that is displaced as the steering shaft rotates. With a worm reducer to transmit to
The worm speed reducer is provided with a worm wheel rotatably supported in the housing and a worm tooth at an intermediate portion in the axial direction, and the worm gear rotates with the worm wheel meshed with the worm wheel. Having a worm supported freely,
In the electric assist device in which the output shaft of the electric motor and the worm are connected to each other by a torque transmission joint so that torque can be transmitted.
Said torque transmitting joint, the torque transmitting coupling according to claim 1 or 2, electric assist device.

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