JP5387812B2 - Deceleration device and transmission ratio variable steering system - Google Patents

Description

  The present invention is provided between a pair of input / output rotating members facing each other on a first rotating shaft and is capable of changing the transmission ratio of the amount of rotation between them, and the transmission provided with the reducing device The present invention relates to a variable ratio steering system.

As this type of conventional speed reducer, a device described in Patent Document 1 includes a pair of relay gears that are integrally rotated by a motor between opposed surfaces of a pair of input / output rotating members. A third gear having a different number of teeth is connected between the input rotating member and one of the relay gears by a first gear and a second gear having different numbers of teeth, and the other relay gear and the output rotating member having a different number of teeth. And the fourth gear. The output shaft extending from the rotor of the motor extends through the output rotating member to a region between the pair of input / output rotating members, and intersects the first rotating shaft obliquely at a portion located in the region. The second rotating shaft portion is provided. The second rotating shaft portion passes through the center portion of the pair of relay gears and rotatably supports the relay gears. When the motor rotates, the second rotating shaft rotates so as to draw a cone, so that the pair of relay gears swing, and the meshing position of the first gear and the second gear and the third gear and the second gear. The meshing position with the four gears moves in the circumferential direction. Thereby, the rotation of the motor is decelerated according to the difference in the number of teeth between the first gear and the second gear and the difference in the number of teeth between the third gear and the fourth gear, and transmitted to the output rotating member. It was.
JP 2006-82718 A (paragraphs [0037] to [0039], FIG. 2)

  However, in the conventional reduction gear described above, the motor that is the drive source of the relay gear is arranged side by side in the facing direction of the pair of input / output rotation members (the direction of the first rotation shaft). There is a problem that the variable ratio steering system becomes longer in the direction of the first rotation axis.

  The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a speed reducer and a transmission ratio variable steering system capable of shortening the length of a pair of input / output rotating members in the rotation axis direction as compared with the conventional one. And

The speed reducer (20) according to the invention of claim 1 made to achieve the above object is a region between a pair of input / output rotating members (31, 32) facing each other on the first rotating shaft (X1). Is surrounded by a rotation drive sleeve (45), and the input / output rotation members (31, 32) and the rotation drive sleeve (45) are rotatable about the first rotation axis (X1), and the rotation drive sleeve (45 ) For the first rotation of the inner (50B) of the bearing (50) comprising the outer (50A), the inner (50B) and the ball (50C) between the outer (50A) and the inner (50B). A pair of relay gears that are rotatable about a second rotation shaft (X2) that obliquely intersects the shaft (X1), and that are provided back to back at both axial ends of the inner (50B) and rotate together. (41 , 42G) is engaged with a pair of input / output gears (31G, 32G) formed on the opposing surfaces of the pair of input / output rotation members (31, 32). ) Between the pair of relay gears (41G, 42G) and the inner (50B). ) Is formed in a flange portion (42B) projecting radially outward from one end portion in the axial direction to between the outer (50A) and the inner (50B) .

The invention of claim 2 is the speed reduction device (20) according to claim 1 , further comprising press-fit shaft portions (41A, 42A) that can be press-fitted to an intermediate position in the width direction of the bearing (50). 41A, 42A) is provided with a pair of relay rotating members (41, 42) having a structure in which the flange portions (41B, 42B) protrude from the rear ends, and the pair of relay rotating members (41, 42) are provided with bearings (50). ) Is symmetrically assembled.

The invention according to claim 3, in the deceleration device according to claim 2 (20), between the press-fit the shaft portion (41A, 42A) and the bearing (50), or press-fit the shaft portion (41A, 42A) between each other Further, it has a feature in that a concave and convex engaging portion (40A) for prohibiting idling is provided.

A fourth aspect of the present invention, the reduction gear transmission of claim 1 (20), a pair of flange portions at both ends in the axial direction of the inner (50B) (41B, 42B) and integrally formed, an inner (50B ) Is characterized by a cross-sectional groove shape.

According to a fifth aspect of the present invention, in the speed reducer (20) according to any one of the first to fourth aspects, the rotary drive sleeve (45) is a hollow rotor (45) provided in the cylindrical motor (43). However, it has characteristics.

The transmission ratio variable steering system (100) according to the invention of claim 6 is in the middle of the steering transmission shaft (17) for transmitting the steering of the handle (16) of the vehicle (10) to the steered wheels (11, 11). The speed reduction device (20) according to any one of claims 1 to 5 is provided, and the transmission ratio of the steering angle from the steering wheel (16) to the steered wheels (11, 11) can be changed.

[Inventions of Claims 1 , 2, 4 , and 5 ]
The speed reducer according to claim 1 configured as described above surrounds a region between the pair of input / output rotating members with a rotary drive sleeve, and an inner bearing of the rotary drive sleeve is defined as a first rotary shaft. It was made rotatable about the second rotation axis that crossed diagonally. In addition, a pair of relay gears that mesh with the input / output gears formed on the opposing surfaces of the pair of input / output rotating members and rotate integrally with each other are provided back-to-back at both axial ends of the inner. As a result, the drive source of the pair of relay gears can be disposed on the side of the pair of relay gears, and the length in the direction of the first rotating shaft can be made shorter than before. .

Here, the outer peripheral surface of the rotational drive sleeve may be gear-coupled to a motor that rotates about the rotational axis offset from the first rotational axis, and the rotational drive sleeve may be rotated by the motor. As in the invention of claim 5 , the rotary drive sleeve itself may be constituted by a hollow rotor provided in a cylindrical motor.

According to the invention of claim 1, at least one relay gear of the pair of relay gears is formed on the flange portion projecting radially outward from one end portion in the axial direction of the inner portion to between the outer portion and the inner portion. Since it is formed, the meshing pitch diameter of the input / output gear and the relay gear can be increased without increasing the outer diameter of the bearing.

Here, as in the invention of claim 4, a pair of flange portions may be integrally formed at both ends in the axial direction of the inner, and the inner may be formed into a cross-sectional groove shape. You may comprise with another component. Specifically, as in the invention of claim 2 , a relay rotating member having a structure in which a press-fit shaft portion that can be press-fitted to an intermediate position in the width direction of the bearing is provided and a flange portion projects from the rear end of the press-fit shaft portion. A pair of relay rotating members may be provided symmetrically to the bearing. According to the invention of claim 4 , the number of parts can be reduced as compared with the case where the pair of flange portions are constituted by separate parts from the inner.

[Invention of claim 3 ]
According to the invention of claim 3 , when a torque is applied to the pair of relay rotating members from the input / output rotating member, the idle rotation between the pair of relay rotating members and the bearings or the pair of relay rotating members Relative rotation can be reliably prohibited.

[Invention of claim 6 ]
Since the transmission ratio variable steering system according to claim 6 configured as described above includes the speed reduction device according to any one of claims 1 to 6 , the transmission ratio variable steering system is arranged in the direction of the first rotation shaft. It can be made shorter than before.

  Hereinafter, a first embodiment according to the present invention will be described with reference to FIGS. FIG. 1 shows an entire vehicle 10 equipped with a transmission ratio variable steering system 100 of the present invention. A rack 12 is passed between a pair of front wheels 11, 11 (corresponding to a “steered wheel” according to the present invention) of the vehicle 10, and both ends of the rack 12 are respectively connected via tie rods 13, 13. It is connected to the front wheels 11. The rack 12 is accommodated in a rack case 12C fixed to the body 14 of the vehicle 10 so as to be able to move directly, and meshes with a pinion 15 provided in an intermediate portion of the rack case 12C.

  The pinion 15 and the handle 16 are connected by a steering shaft 17. The steering shaft 17 includes a first steering shaft 18 on the handle 16 side and a second steering shaft 19 on the pinion 15 side. As shown in FIG. 2, the ends of the first and second steering shafts 18 and 19 are abutted in a housing 21 fixed to the body 14 of the vehicle 10 and arranged on a common first rotation axis X1. In such a state, the speed reducer 20 according to the present invention is provided between them. Universal joints 18J and 19J are provided at intermediate portions of the first steering shaft 18 and the second steering shaft 19, respectively.

  As shown in FIG. 2, the second steering shaft 19 has a structure in which the entire shaft shaft 191 except the upper end portion on the handle 16 side is covered with a shaft sleeve 192. The core shaft 191 has a relatively large diameter at both axial end portions and a relatively thin intermediate portion. The shaft sleeve 192 has a cylindrical shape extending in the vertical direction, and includes an upper sleeve 193 and a lower sleeve 194. The upper sleeve 193 covers the upper half of the core shaft 191 and is fitted and fixed to a portion near the upper end of the core shaft 191.

  The lower sleeve 194 extends upward from the lower end of the core shaft 191. The lower sleeve 194 is splined to the lower end of the upper sleeve 193, and the lower end of the core shaft 191 protruding from the lower end of the upper sleeve 193 is fitted and fixed to the lower end of the lower sleeve 194.

  The transmission ratio variable steering system 100 is configured to house a cylindrical motor 43 inside the housing 21, decelerate the rotation of the cylindrical motor 43, and output it to the second steering shaft 19. As shown in FIG. 2, the housing 21 includes an upper end plate 22, a motor housing 23, an inner housing 24, and a lower end plate 25 in order from the first steering shaft 18 side to the second steering shaft 19 side. These are fastened to each other by bolts 26.

  The upper end plate 22 has a structure in which a shaft insertion hole 22B is formed through the central portion of the disc wall 22A, and the shaft housing cylinder portion 22C stands upward from the peripheral edge thereof (to the handle 16 side). The lower end portion of the first steering shaft 18 is inserted into the housing 21 from the shaft insertion hole 22B.

  The motor housing 23 has a cylindrical structure with one end and opened downward (to the pinion 15 side), and the bottom wall 23 </ b> A is assigned to the disk wall 22 </ b> A of the upper end plate 22. A bottom wall through hole 23B that is coaxial with the shaft insertion hole 22B formed in the upper end plate 22 is formed in the center of the bottom wall 23A. The bottom wall 23A extends downward from the peripheral edge of the bottom wall through hole 23B (on the pinion 15 side). The bearing fitting cylinder portion 23C extends toward the end.

  The inner housing 24 has a disc wall 24A in which the lower end opening of the motor housing 23 is closed, and a central portion of the disc wall 24A includes the shaft insertion hole 22B and a bottom wall through hole 23B formed in the motor housing 23. A coaxial inner insertion hole 24B is formed so as to penetrate therethrough, and the inner cylinder portion 24C stands upward from the opening edge of the inner insertion hole 24B (toward the handle 16).

  The lower end plate 25 has a flat cup shape with a lower end and sandwiches a portion near the outer edge of the inner housing 24 between the upper end opening edge of the cylindrical wall 25 </ b> A and the lower end opening edge of the motor housing 23. Further, a bearing fitting hole 25B that is coaxial with the shaft insertion hole 22B, the bottom wall through hole 23B, and the inner insertion hole 24B is formed in the center of the bottom wall 25C of the lower end end plate 25 so as to pass therethrough. A steering shaft 19 is inserted into the housing 21 through the bearing fitting hole 25B.

  An input side rotation base 31 is attached to the lower end portion of the first steering shaft 18. The input-side rotation base 31 includes a connecting cylinder portion 31A splined to the lower end portion of the first steering shaft 18, and a flange portion 31B projecting radially outward from the lower end of the connecting cylinder portion 31A. . The connecting cylinder portion 31A is loosely fitted inside the bearing fitting cylinder 23C in the motor housing 23, and a bearing 52 is fitted between the inner peripheral surface of the bearing fitting cylinder 23C and the outer peripheral surface of the connecting cylinder portion 31A. Are combined. Thereby, the input side rotation base 31 rotates together with the first steering shaft 18 and rotates relative to the housing 21. Further, an input side gear 31G in which tooth traces extend radially is formed on the lower surface of the flange portion 31B, that is, the surface facing the output side rotation base 32 described later. The input side gear 31G is formed at a radially outward position on the lower surface of the flange portion 31B.

  As shown in FIG. 2, the second steering shaft 19 passes through the bearing fitting hole 25 </ b> B of the lower end plate 25 and the inner insertion hole 24 </ b> B of the inner housing 24, and the upper end of the second steering shaft 19 is the bearing of the motor housing 23. It extends to the inside of the fitting cylinder 23C. And the upper end part exposed from the shaft sleeve 192 among the 2nd steering shaft 19 has plunged into the inner side of the input side rotation base 31 (specifically connection cylinder part 31A).

  Between the outer peripheral surface of the upper end portion of the second steering shaft 19 and the inner peripheral surface of the connecting cylinder portion 31A, a bearing 53 (specifically, a bearing having a plurality of needles as rolling elements) is provided. Also, bearings 54 and 55 are fitted between the second steering shaft 19 and the bearing fitting hole 25B and between the inner insertion hole 24B, respectively. By these bearings 53, 54 and 55, the second steering shaft 19 is pivotally supported so as to rotate relative to the housing 21 and the first steering shaft 18.

  An output side rotation base 32 is attached to a position near the upper end of the second steering shaft 19. The output side rotation base 32 is disposed opposite to the input side rotation base 31 on the first rotation axis X1. The output side rotation base 32 includes a connecting cylinder portion 32A splined to the outer peripheral surface of the shaft sleeve 192 (upper sleeve 193), and a flange portion 32B projecting radially outward from the upper end of the connecting cylinder portion 31A. ing. The coupling cylinder part 32A is loosely fitted inside the inner cylinder part 24C of the inner housing 24, and a bearing 56 is fitted between them. As a result, the output side rotation base 32 rotates integrally with the second steering shaft 19 and rotates relative to the housing 21. Further, an output side gear 32G in which tooth traces extend radially is formed on the upper surface of the flange portion 32B, that is, the surface facing the flange portion 31B of the input side rotation base 31. The output side gear 32G is formed at a radially outward position on the upper surface of the flange portion 32B. The input side rotation base 31 and the output side rotation base 32 correspond to “a pair of input / output rotation members” of the present invention (see FIG. 3).

  A center gear 40 is disposed between the flange portion 31B of the input side rotation base 31 and the flange portion 32B of the output side rotation base 32. In the center gear 40, a pair of relay gears 41G and 42G having tooth traces extending radially are provided on the surface facing the flange portions 31B and 32B.

  As shown in FIG. 3, in the center gear 40, the surface facing the flange portion 31B of the input side rotation base 31 can mesh with the input side gear 31G and has a number of teeth different from the number N1 of teeth of the input side gear 31G. An N2 relay gear 41G is formed, and the surface facing the flange portion 32B of the output side rotation base 32 has a number of teeth N3 that can mesh with the output side gear 32G and is different from the number N4 of teeth of the output side gear 32G. A relay gear 42G is formed. Hereinafter, when the pair of relay gears 41G and 42G are distinguished, they are referred to as “input-side relay gear 41G” and “output-side relay gear 42G”.

  The center gear 40 is rotationally driven by a cylindrical motor 43 accommodated in the housing 21. The cylindrical motor 43 includes a stator 44 fixed to the inner peripheral surface of the motor housing 23, and a hollow rotor 45 that rotates inside the stator 44. The rotor 45 has a substantially cylindrical structure, and a magnet 45M is fixed at a position facing the stator 44 on the outer peripheral surface thereof.

  The rotor 45 extends between the inner cylinder portion 24C and the bearing fitting cylinder portion 23C so as to surround a region between the input side rotation base 31 and the output side rotation base 32, and the outer peripheral surfaces thereof. A pair of bearings 57 and 58 (specifically, bearings using a plurality of needles as rolling elements) are fitted between the inner peripheral surface of the rotor 45 and the rotor 45. Thus, the rotor 45 is supported so as to be rotatable relative to the housing 21, the input side rotation base 31 (first steering shaft 18), and the output side rotation base 32 (second steering shaft 19). The rotor 45 corresponds to the “rotary drive sleeve” of the present invention.

  Here, a resolver 48 for detecting the rotational position of the rotor 45 is provided near the opening end of the motor housing 23. The resolver 48 includes a resolver rotor 48 </ b> R that rotates integrally with the rotor 45, and a resolver stator 48 </ b> S fixed to the motor housing 23.

  A cylinder centering on a second rotation axis X2 inclined at an angle θ with respect to the first rotation axis X1 is located at an intermediate position between the pair of bearings 57 and 58 on the inner peripheral surface 45A of the rotor 45. A shape fitting surface 46 is formed (see FIG. 4B). When the rotor 45 rotates, the second rotation axis X2 rotates so as to draw a cone having the first rotation axis X1 as the central axis. The cylindrical fitting surface 46 is fitted with a bearing 50 that holds the center gear 40 rotatably inside the rotor 45.

The bearing 50 is a ball bearing in which a plurality of balls 50C are rotatably held between an outer race 50A (corresponding to the “outer” of the present invention) and an inner race 50B (corresponding to the “inner” of the present invention). The outer race 50 </ b> A is fitted and fixed to the cylindrical fitting surface 46. Further, the inner race 50B is rotatable around a second rotation axis X2 that obliquely intersects the first rotation axis X1 of the first and second steering shafts 18 and 19 at an angle θ. And the center gear 40 is assembled | attached to the inner race 50B so that integral rotation is possible (refer FIG. 4 (A)). That is, the center gear 40 can rotate relative to the rotor 45 about the second rotation axis X2. Further, as shown in FIG. 3, the input side gear 31G of the input side rotation base 31 and the input side relay gear 41G of the center gear 40 partially mesh with each other in a part in the circumferential direction, and about 180 degrees from the meshing position. The output side relay gear 42G of the center gear 40 and the output side gear 32G of the output side rotation base 32 are partially engaged with each other at a distant position. Further, as the rotor 45 rotates, the meshing position of the input side gear 31G and the input side relay gear 41G and the meshing position of the output side relay gear 42G and the output side gear 32G move in the circumferential direction. Yes. Here, a step surface 45B substantially perpendicular to the cylindrical fitting surface 46 is formed on the lower end side of the cylindrical fitting surface 46 in the inner peripheral surface 45A of the rotor 45, and a bearing is formed on the step surface 45B. The end surfaces of the 50 outer races 50A are in contact with each other to position the bearing 50.

  The center gear 40 is constituted by a pair of relay rotating members 41 and 42. The pair of relay rotating members 41 and 42 includes press-fit cylinder portions 41A and 42A (corresponding to the “press-fit shaft portion” of the present invention) that can be press-fitted to an intermediate position in the width direction of the inner race 50B, and a press-fit cylinder portion 41A. , 42A and flange portions 41B, 42B projecting laterally from the rear end, and the pair of relay rotating members 41, 42 are assembled symmetrically with respect to the bearing 50. Of the pair of relay rotating members 41 and 42, the input side relay gear 41G is formed on the flange portion 41B of the relay rotating member 41 assembled on the input side rotating base 31 side of the bearing 50, and the output side rotating base. An output-side relay gear 42G is formed on the flange portion 42B of the relay rotating member 42 assembled on the 32 side. That is, a pair of relay gears 41G and 42G are provided back to back with the inner race 50B interposed therebetween (see FIG. 4).

  The above is the description regarding the speed reducer 20 and the transmission ratio variable steering system 100 of the present invention. Next, the operation of this embodiment will be described. In this variable transmission ratio steering system 100, the rotation of the first steering shaft 18 accompanying the operation of the handle 16 is caused by the input side rotation base 31, the center gear 40 (a pair of relay rotation members 41, 42), the output side rotation base. 32 to the second steering shaft 19. Further, the rotation of the rotor 45 of the cylindrical motor 43 is decelerated and transmitted to the second steering shaft 19. Then, the rotational transmission ratio between the input-side and output-side rotary bases 31 and 32 can be changed by the rotational drive of the rotor 45.

  That is, when the first steering shaft 18 rotates, the center gear 40 meshes the relay gear 41G with the input side gear 31G of the input side rotation base 31, and the output side relay gear 42G becomes the output side gear of the output side rotation base 32. In the state of meshing with 32G, it rotates around the second rotation axis X2. At this time, when the cylindrical motor 43 is driven, the difference in the number of teeth between the input-side gear 31G and the input-side relay gear 41G and the difference in the number of teeth between the output-side relay gear 42G and the output-side gear 32G The rotation is decelerated, and the decelerated rotation is transmitted to the second steering shaft 19. Thereby, the transmission ratio of the steering angle from the steering wheel 16 to the steered wheels 11, 11 can be changed between the first and second steering shafts 18, 19.

  Hereinafter, the operation of the reduction gear 20 will be described in detail. For convenience of explanation, a case where the first steering shaft 18 is fixed and the rotor 45 rotates with respect to the first steering shaft 18 will be described.

  When the rotor 45 rotates, the center gear 40 fitted to the cylindrical fitting surface 46 of the rotor 45 via the bearing 50 rotates integrally. At this time, since the second rotation axis X2 rotates so as to draw a cone with the first rotation axis X1 as the center axis, the center gear 40 is as if between the input side rotation base 31 and the output side rotation base 32. Swing around like a soloist just before stopping. That is, it swings in the direction of the thick arrow shown in FIG. 3 while rotating around the first rotation axis X1 integrally with the rotor 45.

  When the center gear 40 swings, the meshing position of the input side relay gear 41G of the center gear 40 and the input side gear 31G of the input side rotation base 31 and the output side relay gear 42G and output side of the center gear 40 are obtained. The meshing position of the rotation base 32 with the output side gear 32G moves in the circumferential direction (around the first rotation axis X1). Then, the center gear 40 rotates with respect to the rotor 45 by the difference in the number of teeth between the input side gear 31G and the input side relay gear 41G. Further, the output side rotation base 32 rotates relative to the rotor 45 by the difference in the number of teeth between the output side relay gear 42G and the output side gear 32G.

  For example, when the number of teeth N1 of the input side gear 31G of the input side rotation base 31 is "100" and the number of teeth N2 of the input side relay gear 41G of the center gear 40 is "101", the rotor 45 rotates once in the forward direction. The center gear 40 rotates forward by 1/100 with respect to the rotor 45. Further, for example, when the number of teeth N1 of the input side gear 31G is “100” and the number of teeth N2 of the input side relay gear 41G is “99” and the rotor 45 rotates once in the forward direction, the center gear 40 is moved to the rotor. Reverse rotation by 1/100 with respect to 45. That is, when the rotor 45 rotates once, the center gear 40 rotates in the same direction or in the opposite direction by (N2-N1) / N1 with respect to the rotor 45.

  Similarly, the number of teeth N3 of the output-side relay gear 42G of the center gear 40 is set to “100”, and the number of teeth N4 of the output-side gear 32G of the output-side rotating base 32 is set to “101”. In this case, the output side rotation base 32 rotates forward by 1/100 with respect to the rotor 45. Further, for example, when the number of teeth N3 of the output-side relay gear 42G is set to “100” and the number of teeth N4 of the output-side gear 32G is set to “99”, the rotor 45 is rotated once in the forward direction. Rotates counterclockwise by 1/100 with respect to the rotor 45. That is, when the rotor 45 rotates once, the output side rotation base 32 rotates in the forward direction or the reverse direction by (N4−N3) / N3 with respect to the rotor 45.

  Here, the number of teeth N1 to N4 of each gear 31G, 32G, 41G, and 42G and the rotation speed (reduction ratio) R of the output side rotation base 32 when the rotor 45 makes one rotation are expressed by the following relational expression. The

      R = 1− (N4 × N2) / (N3 × N1)

As described above, in the speed reduction device 20 and the transmission ratio variable steering system 100 according to the present embodiment, the region between the input side rotation base 31 and the output side rotation base 32 is surrounded by the rotor 45 of the cylindrical motor 43 and the inner side of the rotor 45. The inner race 50 </ b> B of the bearing 50 provided at the center is rotatable about a second rotation axis X <b> 2 that obliquely intersects the first rotation axis X <b> 1. A pair of relay gears 41G and 42G meshing with the input side gear 31G of the input side rotation base 31 and the output side gear 32G of the output side rotation base 32 and rotating integrally with each other are connected to both ends of the inner race 50B in the axial direction. The parts were provided back to back. Since the motor 43 that is the drive source of the pair of relay gears 41G and 42G is arranged on the side of the relay gears 41G and 42G so as to surround the region between the input side rotation base 31 and the output side rotation base 32. The length in the direction of the first rotation axis X1 can be made shorter than before.

Further, a pair of relay gears 41G and 42G are formed on a pair of flange portions 41B and 42B projecting radially outward from both axial sides of the inner race 50B to between the outer race 50A and the inner race 50B . Therefore, the meshing pitch diameter between the input side gear 31G and the input side relay gear 41G and the meshing pitch diameter between the output side gear 32G and the output side relay gear 42G can be increased without increasing the outer diameter of the bearing 50. Yes (see FIG. 4).

[Other Embodiments]
The present invention is not limited to the above-described embodiment. For example, the embodiments described below are also included in the technical scope of the present invention, and various other than the following can be made without departing from the scope of the invention. It can be changed and implemented.

( 1 ) Here, when the pair of relay gears 41G and 42G is formed on the inner race 50B of the bearing 50, as shown in FIG. 5 (A), radially outward from both axial ends of the inner race 50B. A pair of flange portions 41B and 42B projecting on the inner race 50B are integrally formed with the inner race 50B, and the inner race 50B is formed into a cross-sectional groove shape (concave shape). 41G and 42G may be formed.

( 2 ) Further, only one of the pair of relay gears 41G and 42G is formed integrally with the inner race 50B, and the other is formed on the inner race 50B like the relay rotating members 41 and 42 described in the first embodiment. It is good also as an assembled structure. For example, as shown in FIG. 5 (B), while the input-side relay gear 41G (output-side relay gear 42G) integrally formed on one axial end of the inner race 50B, the inner axial direction of the inner race 50B on the opposite side The relay rotation member 42 (relay rotation member 41) may be assembled at the end .

( 3 ) In order to reliably prevent idle rotation between the relay rotating members 41, 42 and the inner race 50B of the bearing 50, the inner peripheral surface of the inner race 50B and the press-fit cylinder portions 41A, 42A of the relay rotating members 41, 42 are provided. Concave and convex engagement (for example, spline coupling) may be performed between the outer peripheral surface and the outer peripheral surface. Further, in order to prevent relative rotation between the intermediary rotary member 41, as shown in FIG. 5 (C), which recess-projection engaging in the insertion direction into the inner race 50B between the press-fit tube portion 41A, 42A An uneven engagement portion 40A may be provided.

( 4 ) In the above embodiment, the center gear 40 (the pair of relay rotating members 41 and 42) is held by the hollow rotor 45 provided in the cylindrical motor 43. The region between the bases 31 and 32 is covered with a rotation drive sleeve, and a gear portion is formed on the outer peripheral surface of the rotation drive sleeve, and the motor and the rotation drive sleeve rotate around a rotation axis offset from the first rotation axis X1. The rotary drive sleeve may be rotated by a motor by gear coupling with the outer peripheral surface of the motor.

( 5 ) As a bearing used for the rotating portion of the speed reduction device 20 and the transmission ratio variable steering system 100 of the above-described embodiment, a ball bearing (ball bearing), a roller bearing (needle bearing), and other bearings may be appropriately selected and used. .
Although not belonging to the technical scope of the present invention, as shown in FIGS. 6 and 7 as a reference example, a pair of relay gears 41G and 42G are integrally formed on both end surfaces of the inner race 50B of the bearing 50 in the axial direction. It may be formed. In this way, the number of parts can be reduced. Further, although not shown, a raceway groove on which the ball 50C rolls may be formed on the cylindrical fitting surface 46 of the rotor 45 so that the rotor 45 also serves as the outer race 50A of the bearing 50.

The conceptual diagram of the vehicle provided with the transmission ratio variable steering system which concerns on one Embodiment of this invention. Cross section of transmission ratio variable steering system Cross section of reduction gear (A) Enlarged cross-sectional view of rotor, (B) Cross-sectional view of bearing and relay rotating member Sectional drawing of the bearing and relay rotation member which concern on a modification Sectional view of variable transmission ratio steering system according to reference example Sectional view of bearing and relay rotating member according to reference example

Explanation of symbols

10 Vehicle 11, 11 Front wheel (steering wheel)
16 Steering wheel 17 Steering shaft (steering transmission shaft)
20 Reduction gear 31 Input side rotation base (input / output rotation member)
31G Input side gear (I / O gear)
32 Output-side rotating base (input / output rotating member)
32G output side gear (input / output gear)
40A Concavity and convexity engaging portion 41, 42 Relay rotating member 41A, 42A Press-fit cylinder portion (press-fit shaft portion)
41B, 42B Flange 41G Input side relay gear (relay gear)
42G Output side relay gear (relay gear)
43 Cylindrical motor 45 Rotor (rotary drive sleeve)
50 Bearing 50A Outer race 50B Inner race 100 Transmission ratio variable steering system X1 First rotation axis X2 Second rotation axis

Claims (6)

A region between a pair of input / output rotation members facing each other on the first rotation shaft is surrounded by a rotation drive sleeve, and the input / output rotation member and the rotation drive sleeve are rotatable about the first rotation shaft. , provided inside the rotary drive sleeve outer, inner and rotatable about a second rotation axis bearing said inner consisting of ball crossed diagonally with the first rotation axis between these outer and inner age,
A pair of relay gears, which are provided back to back at both ends in the axial direction of the inner and rotate integrally with each other, mesh with a pair of input / output gears formed on opposing surfaces of the pair of input / output rotating members. The transmission ratio of the rotation amount between the pair of input / output rotation members can be changed by the rotation drive of the rotation drive sleeve,
The at least one relay gear of the pair of relay gears is formed in a flange portion projecting radially outward from one end portion in the axial direction of the inner portion to between the outer portion and the inner portion. To reduce the speed.   A relay rotary member having a structure in which a press-fit shaft portion that can be press-fitted to an intermediate position in the width direction of the bearing is provided and the flange portion projects from the rear end of the press-fit shaft portion is provided as a pair. The speed reducer according to claim 1, wherein the speed reducer is assembled symmetrically to the bearing.   The speed reducer according to claim 2, wherein an uneven engagement portion for prohibiting idle rotation is provided between the press-fit shaft portion and the bearing or between the press-fit shaft portions. .   The speed reducer according to claim 1, wherein a pair of the flange portions are integrally formed at both ends in the axial direction of the inner, and the inner is formed into a cross-sectional groove shape.   The reduction gear according to any one of claims 1 to 4, wherein the rotation drive sleeve is a hollow rotor provided in a cylindrical motor.   A reduction device according to any one of claims 1 to 5 is provided in the middle of a steering transmission shaft for transmitting steering of a vehicle handle to a steered wheel, and a transmission ratio of a steering angle from the handle to the steered wheel is set. A transmission ratio variable steering system characterized in that it can be changed.