JP2006082718A - Steering device with variable steering angle ratio - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering device with variable steering angle ratio capable of reducing the noise and vibration using Coriolis motion gears and of establishing a low-cost construction. <P>SOLUTION: The steering device with variable steering angle ratio has a reduction gear 19 which is equipped with an outer ring gear part 194c of a swinging gear 194 having a first gear 191 fixed to an upper steering shaft 2, a fourth gear 192 set on a lower steering shaft 4 with the rotation restrained, a tilting shaft 193 coupled with a motor shaft 143 and having an inclined peripheral surface 193b1, a second gear supported rotatably on the inclined peripheral surface 193b1 and meshing with the first gear 191, and a third gear to mesh with the fourth gear 192. Further, an axial direction pressing spring 195 to give an axially directed force toward the swinging gear 194 to the fourth gear 192 is installed at a housing 13 coupled rigidly with the upper steering shaft 12. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a steering angle ratio variable steering apparatus.

  The steering angle ratio variable steering device can vary the steering angle ratio of the turning angle of the lower steering wheel with respect to the steering angle of the upper steering shaft. The steering angle ratio variable steering apparatus includes a steering angle ratio variable motor and a reduction gear. And this reduction device uses the reduction gear which consists of a planetary gear mechanism, the reduction gear which consists of a wave gear mechanism, etc. (for example, refer patent document 1).

  However, a reduction gear composed of a planetary gear mechanism, a wave gear mechanism, and the like generates radial rattle between the gears, generates tooth contact noise and rubbing noise, and causes noise and vibration. Moreover, although the said problem can be reduced by improving the processing precision and surface roughness of a gear, it leads to a cost increase.

By the way, as a reduction gear, the reduction gear using what is called a Coriolis movement gear other than a planetary gear mechanism and a wave gear mechanism is indicated (for example, refer to patent documents 2).
Japanese Patent No. 3189627 JP-A-11-315892

  The present invention has been made in view of such circumstances, and provides a variable steering angle ratio steering device that can reduce noise and vibration and reduce costs by using a so-called Coriolis motion gear. The purpose is to do.

  A steering angle ratio variable steering apparatus according to the present invention includes an upper steering shaft that is connected to a steering wheel and transmits a steering angle of the steering wheel, and is disposed substantially coaxially with the upper steering shaft and outputs a motor to the upper steering shaft. A variable steering angle ratio motor capable of rotating the shaft relatively, a reduction gear connected to the motor output shaft and outputting a turning angle with a reduced motor rotation angle of the motor output shaft, and the rotation output from the reduction gear. A lower steering shaft that transmits a steering angle to a steered wheel side, and a device that varies a steering angle ratio of the steered angle with respect to the steered angle.

  A characteristic feature of the steering angle ratio variable steering apparatus according to the present invention is that the speed reducer is rotationally restrained by the upper steering shaft and has a first gear having a first tooth with n1 teeth on the end surface, and the lower gear. A fourth gear having a fourth tooth having a number of teeth n4 formed on an end surface facing the end surface of the first gear, the rotation being restricted by the steering shaft; and a rotation shaft of the motor output shaft fixed to the motor output shaft An inclined shaft having a tilted rotation axis inclined at a predetermined angle as a center and an inclined shaft formed on the outer peripheral side, and between the first gear and the fourth gear and rotatably supported on the tilted surface. A second gear that meshes with the first gear and has a second tooth having a number of teeth n2 and a third gear that meshes with the fourth gear and has a third tooth having a number of teeth n3 formed on an end surface. A first common passing through each pitch circle of the first gear and the second gear A swing gear and the center point of the second common spherical matches through each pitch circle of the third gear and the fourth gear and the center point of the surface, is to comprise a.

  Thus, according to the steering angle ratio variable steering apparatus of the present invention, radial backlash can be eliminated by using a so-called Coriolis motion gear. Thereby, generation | occurrence | production of a noise and a vibration can be reduced. Furthermore, with the above configuration, radial play can be eliminated without further reducing play by further improving the processing accuracy and surface roughness of the gear. That is, cost reduction can be achieved.

  The Coriolis movement gear is a gear composed of at least the first gear, the fourth gear, the tilt shaft, and the swing gear among the members constituting the reduction gear of the steering angle ratio variable steering device of the present invention described above. Means.

  Next, the present invention will be described in more detail with reference to embodiments.

  As described above, the steering angle ratio variable steering apparatus of the present invention includes the upper steering shaft, the housing, the steering angle ratio variable motor, the speed reducer, and the lower steering shaft. Furthermore, as described above, the speed reducer includes a first gear, a fourth gear, an inclined shaft, and a swing gear.

(1) Axial force imparting member The steering angle ratio variable steering device according to the present invention is further provided for the upper steering shaft, the lower steering shaft, the upper steering shaft, or the housing fixedly disposed on the lower steering shaft. It is preferable that at least one of the first gear and the fourth gear be provided with an axial force applying member that applies an axial force toward the swinging gear. As described above, the axial force application member that presses the first gear or the fourth gear toward the swing gear side includes the axial gap between the first gear and the second gear, and the shafts of the third gear and the fourth gear. It acts to narrow the gap in the direction. As a result, the axial gap (backlash) can be further reduced. Therefore, noise and vibration can be further reduced.

  Here, the axial force applying member is a member that applies an axial force to the first gear toward the swing gear with respect to the upper steering shaft or a housing fixedly disposed on the upper steering shaft, and upper steering. A member that applies axial force to the fourth gear to the swing gear side with respect to a housing that is fixedly disposed on the shaft or the upper steering shaft; a housing that is fixedly disposed on the lower steering shaft or the lower steering shaft; On the other hand, a member that applies axial force to the first gear on the swing gear side, or a lower steering shaft or a housing that is fixedly disposed on the lower steering shaft, the fourth gear toward the swing gear side. One or more members selected from among members that apply an axial force. Here, the housing is a member that houses the rudder angle ratio variable motor and the reduction gear. And when this housing is fixedly arranged on the upper steering shaft, when fixedly arranged on the lower steering shaft, this housing is fixedly arranged on the vehicle body etc. and can be rotated relative to the upper steering shaft and the lower steering shaft. It may be arranged.

  When the axial force applying member is a member that applies an axial force to the first gear toward the swing gear with respect to the upper steering shaft or the housing fixedly disposed on the upper steering shaft. The first gear needs to be disposed so as to be axially movable with respect to the upper steering shaft or the housing while being rotationally restrained by the upper steering shaft or the housing. Further, when the axial force applying member is a member that applies an axial force toward the swing gear side to the fourth gear with respect to the upper steering shaft or the housing fixedly disposed on the upper steering shaft, The fourth gear needs to be disposed so as to be axially movable with respect to the upper steering shaft or the housing. Further, when the axial force application member is a member that applies an axial force toward the swing gear to the first gear with respect to the lower steering shaft or the housing fixedly disposed on the lower steering shaft, The first gear needs to be arranged so as to be axially movable with respect to the lower steering shaft or the housing. Further, when the axial force application member is a member that applies an axial force toward the swing gear to the fourth gear with respect to the lower steering shaft or the housing fixedly disposed on the lower steering shaft, The fourth gear needs to be disposed so as to be axially movable with respect to the lower steering shaft or the housing while being rotationally restrained by the lower steering shaft or the housing.

  The axial force imparting member may be a spring whose one end in the axial direction presses the upper steering shaft or the lower steering shaft or the housing and whose other end in the axial direction presses the first gear or the fourth gear. Good. For example, the axial force applying member formed of a spring is formed with the first teeth of the first gear when the upper steering shaft or the housing fixedly disposed on the upper steering shaft and the first gear are pressed. The upper steering shaft or the end surface of the housing disposed on the opposite side to the surface on which the first gear is disposed, and the surface opposite to the surface on which the first teeth of the first gear are formed. Further, the axial force applying member formed of a spring is formed with the fourth teeth of the fourth gear when the upper steering shaft or the housing fixedly disposed on the upper steering shaft and the fourth gear are pressed. The upper steering shaft or the end surface of the housing disposed on the opposite side to the surface on which the second gear is disposed are disposed between the surface opposite to the surface on which the fourth teeth of the fourth gear are formed. Further, the axial force imparting member made of a spring is formed with the first teeth of the first gear when the lower steering shaft or the housing fixedly disposed on the lower steering shaft and the first gear are pressed. The lower steering shaft or the end surface of the housing disposed on the opposite side to the surface on which the first gear is disposed, and the surface opposite to the surface on which the first teeth of the first gear are formed. In addition, when the axial force application member formed of a spring presses the lower steering shaft or the housing fixedly disposed on the lower steering shaft and the fourth gear, the fourth tooth of the fourth gear is formed. The lower steering shaft or the end surface of the housing disposed on the opposite side to the surface on which the fourth gear is disposed are disposed on the surface opposite to the surface on which the fourth teeth of the fourth gear are formed.

  Thus, by using such a spring as the axial force applying member, the first gear or the fourth gear can be pressed to the swing gear side reliably and easily at low cost. In addition, as a spring, a disc spring, a wave washer, etc. can be used, for example. Further, the axial force can be appropriately adjusted by the spring force of the spring.

  The axial force applying member is screwed to the upper steering shaft, the lower steering shaft or the housing so as to be movable in the axial direction, and one end side is screwed to press the first gear or the fourth gear. It is good also as a member. As a result, the first gear or the fourth gear can be easily and reliably pressed to the swing gear side. The adjustment of the axial force can be achieved by adjusting the axial position of the screwing member. Here, since the adjustment of the axial position of the screwing member is very easy, the adjustment of the axial force applied to the first gear or the fourth gear can be performed very easily.

  Further, the axial force applying member includes the upper steering shaft or one of an outer ring and an inner ring fixed to the housing fixedly disposed on the upper steering shaft, and an outer ring fixed to the fourth gear. A bearing having either one of the inner rings and capable of applying at least one axial load; and pressing the outer ring of the bearing toward the fourth gear side against the upper steering shaft or the housing. You may make it have a pressing member which gives the 4th gear with the axial direction force to the said rocking | fluctuation gear side with respect to a steering shaft or the said housing. Here, the fourth gear is a member that rotates relative to the upper steering shaft or the housing fixedly disposed on the upper steering shaft. Therefore, the fourth gear may be provided with a bearing (radial bearing) capable of applying a radial load so as to be rotatably supported by the upper steering shaft or the housing. An angular ball bearing or a tapered roller bearing that can apply axial preload to the bearing is used, and the fourth gear is swung with respect to the upper steering shaft or the housing using the preload that can be applied to the bearing. Press to the gear side. In other words, by using a bearing capable of applying an axial load, the fourth gear can be rotatably supported with respect to the upper steering shaft or the housing, and the fourth gear can be securely connected to the swing gear side. Can be pressed. In addition, the spring or screwing member mentioned above can be used for the pressing member which presses a bearing.

(2) Others Further, the steering angle ratio variable steering apparatus of the present invention further includes an engaging member that engages with the outer peripheral surface of the motor output shaft and engages with the inner peripheral surface of the inclined shaft. Also good. Thereby, the motor output shaft and the tilt shaft can be rotated integrally.

  In this case, for example, the radial shape of the outer peripheral surface of the motor output shaft and the radial shape of the engaging member, the radial shape of the inner peripheral surface of the inclined shaft, and the radial shape of the engaging member, At least one of these may have a non-circular shape. For example, it may be a cross or a polygon. As a result, the motor output shaft and the tilt shaft can be rotated together more reliably.

  The inclined shaft may be integrally formed with the motor output shaft. As a result, the motor output shaft and the tilt shaft can be integrally rotated, and the number of components can be reduced, thereby reducing the cost.

  Further, as described above, the variable steering angle ratio steering apparatus of the present invention includes the upper steering shaft, the variable steering angle ratio motor, the speed reducer, and the lower steering shaft. You may make it provide a cable, a locking device, etc. For example, the spiral cable is disposed on the upper steering shaft side of the rudder angle ratio variable motor, and even when the stator of the rudder angle ratio variable motor rotates with respect to the vehicle body, electric power and signals are transmitted to the rudder angle ratio variable motor. It is a cable for enabling supply. The lock device is a device that connects an upper steering shaft or a housing fixedly disposed on the upper steering shaft and a motor output shaft of the steering angle ratio variable motor. In other words, the lock device is a device that rotates the upper steering shaft and the lower steering shaft integrally.

  Next, an Example is given and this invention is demonstrated more concretely.

(1) Overall Configuration of Vehicle Power Steering Device First, the overall configuration of the vehicle power steering device will be described with reference to FIG. FIG. 1 is a diagram showing an overall configuration of a vehicle power steering apparatus. As shown in FIG. 1, the vehicle power steering apparatus mainly includes a steering wheel 1, an upper steering shaft 2, a steering angle ratio variable unit 3, a lower steering shaft 4, and an electric power steering apparatus 5. The Here, the steering angle ratio variable steering apparatus of the present invention is an apparatus that includes the upper steering shaft 2, the steering angle ratio variable unit 3, and the lower steering shaft 4.

  The upper steering shaft 2 is connected to the steering wheel 1 and transmits a steering angle of the steering wheel 1 by the driver. The steering angle ratio variable unit 3 is connected substantially coaxially to the lower end side of the upper steering shaft 2 and to the upper end side of the lower steering shaft 4. The rudder angle ratio variable unit 3 is a unit including a motor (shown in FIG. 2) 14 that varies the rudder angle ratio that is the turning angle of the lower steering shaft 4 with respect to the steering angle of the upper steering shaft 2. Details of the steering angle ratio variable unit 3 will be described later. An outer peripheral spline is formed on the outer peripheral side of the upper end side of the lower steering shaft 4, and an outer peripheral spline of the lower steering shaft 4 is provided on the inner peripheral side of the portion of the rudder angle ratio variable unit 3 that engages with the lower steering shaft 4. An inner peripheral spline is formed that can be engaged with and rotationally restricted.

  The electric power steering device 5 is a rack and pinion type electric power steering device. That is, a pinion (not shown) is formed on the lower end side of the lower steering shaft 4, and the pinion meshes with a rack (not shown). Then, the assist electric motor that constitutes the electric power steering device 5 generates an auxiliary steering force for turning the wheels (steered wheels).

(2) Detailed Configuration of Steering Angle Ratio Variable Unit 3 The steering angle ratio variable unit 3 will be described with reference to FIG. FIG. 2 shows an axial sectional view of the steering angle ratio variable unit 3. As shown in FIG. 2, the rudder angle ratio variable unit 3 includes a first housing 11, a second housing 12, a third housing 13, a motor (steering angle ratio variable motor) 14, a lock device 15, and an angle. A sensor 16, a spiral cable 17, a rubber coupling 18, and a speed reducer 19 are included.

(2.1) Housings 11-13
The first housing 11 has a substantially cylindrical cup shape with a shaft hole formed in the center, and the outer side of the bottom surface, that is, the outer side of the upper end surface (the left side in FIG. 2) is integrally coupled to the upper steering shaft 2. The second housing 12 has a substantially cylindrical shape, and is integrally connected to the inner peripheral surface of the first housing 11 on the opening side (right side in FIG. 2). A female screw is formed on the inner peripheral surface of the second housing 12 on the lower steering shaft 4 side (the right side in FIG. 2). The third housing 13 has a substantially disk shape with a shaft hole formed in the center, and a male screw that can be screwed into a female screw formed in the second housing 12 is formed on the outer peripheral surface. The third housing 13 is screwed into a female screw formed in the second housing 12.

(2.2) Motor 14
The motor 14 is disposed substantially in the center in the axial direction in the first housing 11 and the second housing 12. That is, the motor 14 is disposed in the upper steering shaft 2 side half (the left half in FIG. 2) of the second housing 12. The motor 14 includes a motor housing 141, a stator 142, and a motor shaft (motor output shaft) 143.

  Here, the motor housing 141 includes a motor housing main body 141a and a motor end plate 141b. The motor housing body 141 a has a substantially cylindrical cup shape with a shaft hole formed in the center, and the outer peripheral end is fixed to the second housing 12. The motor end plate 141b has a substantially disk shape with a shaft hole formed in the center. The motor end plate 141b is fixed to the first housing 11 so as to close the opening of the motor housing main body 141a on the upper steering shaft 2 side.

  The stator 142 is formed by winding a winding 142a around a laminated disk-shaped silicon steel plate, and is fixed to the inner peripheral surface of the motor housing body 141a. The motor shaft 143 includes a motor shaft main body 143a and a magnet 143b fixed to the outer peripheral surface of the motor shaft main body 143a. The motor shaft main body 143a is supported by a deep groove ball bearing disposed in the central shaft hole of the motor housing main body 141a and the motor end plate 141b, and is rotatable relative to the housings 11 to 13 and the stator 142 on the same axis. ing. The end of the motor shaft main body 143a on the lower steering shaft 4 side extends on the lower steering shaft 4 side of the deep groove ball bearing supported by the motor housing main body 141a. The radial cross-sectional shape of the end portion of the motor shaft main body 143a on the lower steering shaft 4 side is formed in a substantially cross shape. The magnet 143b of the motor shaft 143 is disposed at a position facing the stator 142 on the outer peripheral surface of the motor shaft main body 143a.

  The motor 14 is angle-controlled so that the turning angle of the lower steering shaft 4 becomes the turning target angle of the lower steering shaft 4 calculated according to the steering angle of the upper steering shaft 2 and the like.

(2.3) Locking device 15
The lock device 15 includes a lock holder 151 and a lock lever 152. The lock holder 151 is fixed to the end of the motor shaft main body 143a on the upper steering shaft 2 side, and lock teeth (not shown) are formed on the outer peripheral surface. The lock lever 152 is swingable about a support shaft (not shown) fixed to the first housing 11, and a lever claw (not shown) that can mesh with the lock teeth of the lock holder 151 on one end side. Is formed. When the lever claw of the lock lever 152 meshes with the lock teeth of the lock holder 151, the first housing 11 and the motor shaft 143 are locked together. On the other hand, when the lever claw of the lock lever 152 is not meshed with the lock teeth of the lock holder 151, the first housing 11 and the motor shaft 143 are unlocked so as to be relatively rotatable. That is, the lock device 15 performs a switching operation between the locked state and the unlocked state.

(2.4) Angle sensor 16
The angle sensor 16 is disposed on the outer peripheral side of the motor shaft main body 143a and between the deep groove ball bearing supported by the motor end plate 141b and the lock device 15. This angle sensor 16 detects the rotation angle of the motor shaft 143.

(2.5) Spiral cable 17
The spiral cable 17 includes a housing 171, an inner cylinder 172, and a flexible flat cable 173. The housing 171 has a substantially cylindrical shape and is fixed to a vehicle body (not shown). The inner cylinder 172 is fixed to the outer peripheral side of the first housing 11 and is disposed inside the housing 171 so as to be relatively rotatable with respect to the housing 171. The flexible flat cable 173 has a plurality of lead wires covered with insulation, and is disposed between the housing 171 and the inner cylinder 172. One end of the flexible flat cable 173 is connected to the inner cylinder 172. The lead wire connected to one end of the flexible flat cable 173 extends from the inner cylinder 172 and is connected to the winding 142a of the stator 142 of the motor 14, the angle sensor 16, and the like. The flexible flat cable 173 has the other end connected to the housing 171. And the lead wire connected to the other end side of the flexible flat cable 173 is extended from the housing 171 and connected to an ECU (not shown) or the like. That is, the spiral cable 17 is a cable for enabling power and signals to be supplied to the motor 14 and the like even when the motor 14 and the like rotate with respect to the vehicle body.

(2.6) Rubber coupling 18
The rubber coupling 18 is made of rubber, and is formed in a ring shape having a substantially cross-shaped radial cross section. The rubber coupling 18 is press-fitted to the end of the motor shaft main body 143a on the lower steering shaft 4 side, and the outer peripheral side is press-fitted to the inner periphery of an inclined shaft 193 of a speed reducer 19 described later. Yes. That is, the rubber coupling 18 is engaged with the motor shaft main body 143a and the inclined shaft 193 so as to eliminate the radial play and to be integrally rotatable.

(2.7) Reducer 19
The reducer 19 uses a so-called Coriolis movement gear mechanism. Below, after demonstrating the schematic structure and detailed structure of the reduction gear 19, operation | movement of the reduction gear 19 is demonstrated. Note that the speed reduction mechanism of the speed reducer 19 in this embodiment uses substantially the same principle as that of a speed reducer composed of a so-called Coriolis motion gear mechanism described in, for example, Japanese Patent Laid-Open No. 11-315892. .

(A) Schematic Configuration of Reducer 19 The reducer 19 is disposed in the second housing 12 on the lower steering shaft 4 side of the motor 14. The speed reducer 19 has one side connected to the motor shaft 143 and the other side connected to the lower steering shaft 4. The speed reducer 19 outputs to the lower steering shaft 4 a turning angle obtained by reducing the input rotation angle (motor rotation angle) of the motor shaft 143.

  The speed reducer 19 is integrally connected to a first gear 191 fixed to the second housing 12, a fourth gear 192 engaged so as to rotationally restrain the lower steering shaft 4, and a motor shaft 143. An oscillating gear 194 having an inclined shaft 193 and a gear that can mesh with the first gear 191 and the fourth gear 192, and an inclined outer peripheral surface (inclined surface) of the inclined shaft 193 disposed so as to be relatively rotatable, An axial pressing spring (axial force applying member, pressing member) 195 that presses the fourth gear 192 against the housing 13 toward the swinging gear 194 is configured.

(B) Detailed structure of the reduction gear 19 Next, each part which comprises the reduction gear 19 is demonstrated in detail with reference to FIGS. FIG. 3 shows an axial sectional view of the fourth gear 192. FIG. 4 shows an axial sectional view of the tilt shaft 193.

(B1) First gear 191
The first gear 191 includes a first gear main body 191a and a plurality of first roller gears (first teeth) 191b. The first gear main body 191a has a substantially disk shape with a shaft hole formed at the center, and n1 radial grooves (not shown) are formed on one end surface (the right side surface in FIG. 2). The first gear body 191a is fixed to the motor 14 side of the inner peripheral side of the second housing 12 so that the radial groove faces the lower steering shaft 4 side. Further, an outer ring of a deep groove ball bearing supported by an outer peripheral surface of an inclined shaft 193 described later is fitted to the inner peripheral surface of the first gear main body 191a. The first roller gear 191b is supported in the radial groove of the first gear main body 191a so as to be rotatable about the radial direction. That is, the first gear 191 is a gear that forms a roller gear having n1 teeth.

(B2) Fourth gear 192
The fourth gear 192 will be described with reference to FIGS. As a whole, the fourth gear 192 has a substantially disk shape with a shaft hole formed in the center. Specifically, the fourth gear 192 includes a lower shaft engaging portion 192a, an inner diameter support portion 192b, an angular ball bearing contact portion 192c, and a fourth roller gear (fourth tooth) 192d. The lower shaft engaging portion 192a has a disk shape with a shaft hole formed in the center. Specifically, the lower shaft engaging portion 192 a is formed with an inner peripheral spline 192 e that can be engaged with an outer peripheral spline formed on the outer periphery on the upper end side of the lower steering shaft 4. Further, an inner ring of an angular ball bearing supported on the inner peripheral surface of the second housing 12 is fitted to the outer peripheral surface of the lower shaft engaging portion 192a. The angular ball bearing supported on the inner peripheral surface of the second housing 12 has a contact angle (from the ball center to the direction vector from the ball center to the axial center to the direction vector toward the position where the roller and the inner ring contact. (Angle) is arranged at a predetermined angle of less than 90 degrees on the upper steering shaft 2 side.

  The inner diameter support portion 192b has a substantially disk shape with a shaft hole formed in the center. The inner diameter support portion 192b has an inner diameter larger than the inner diameter of the lower shaft engaging portion 192a, and has an outer diameter larger than the outer diameter of the lower shaft engaging portion 192a and slightly smaller than the inner diameter of the second housing 12. The inner diameter support portion 192b is integrally coupled to the outer peripheral side of the end surface of the lower shaft engagement portion 192a on the upper steering shaft 2 side. Further, the inner diameter support portion 192b has n4 radial grooves (not shown) formed on one end surface (the left side surface in FIGS. 2 and 3). Further, an outer ring of a deep groove ball bearing supported on an outer peripheral surface of an inclined portion 193 described later is fitted to the inner peripheral surface of the inner diameter support portion 192b.

  The angular ball bearing contact portion 192c is an angular ball bearing supported on the inner peripheral surface of the second housing 12 on the outer peripheral side of the lower shaft engaging portion 192a and on the end surface of the inner diameter support portion 192b on the lower steering shaft 4 side. The end face of the inner ring is in contact. The fourth roller gear 192d is supported rotatably in the radial direction in the radial groove of the inner diameter support portion 192b.

  That is, the fourth gear 192 is a gear that forms a roller gear having n4 teeth. Further, the fourth gear 192 is fixed so as to be rotationally restrained by the lower steering shaft 4 so that the fourth roller gear 192d faces the upper steering shaft 2 side. That is, the fourth gear 192 is arranged so that the fourth roller gear 192d of the fourth gear 192 faces the first roller gear 191b of the first gear 191.

(B3) Inclined shaft 193
The tilt axis 193 will be described with reference to FIGS. The inclined shaft 193 generally has a substantially cylindrical shape with a shaft hole formed at the center. Specifically, the inclined shaft 193 includes a motor connecting portion 193a, a swinging gear support portion 193b, and a fourth gear support portion 193c.

  The motor connecting portion 193a has a substantially disk shape in which a cross hole 193d into which the rubber coupling 18 can be press-fitted is formed at the center. That is, the rotation of the motor shaft 143 is transmitted to the motor connecting portion 193a via the rubber coupling 18. An inner ring of a deep groove ball bearing supported on the inner peripheral surface of the first gear 191 is fitted to the outer peripheral surface of the motor connecting portion 193a. That is, the inclined shaft 193 is rotatable relative to the first gear 191.

  The swing gear support portion 193b has a substantially disk shape with a shaft hole formed in the center, and is integrally coupled to the motor steering portion 193a on the lower steering shaft 4 side. The outer diameter of the oscillating gear support 193b is larger than the outer diameter of the motor connecting portion 193a and smaller than the inner diameter of the first gear main body 191a. Further, an inclined outer peripheral surface (inclined surface) 193b1 is formed on the outer peripheral side of the swinging gear support portion 193b with the rotation axis X2 inclined by a predetermined angle θ with respect to the rotation axis X1 of the inclination shaft 193. Yes. An inner ring of a rocking gear 194, which will be described later, is press-fitted to the inclined outer peripheral surface 193b1. Further, a contact portion 193b2 of the inner ring of the swing gear 194 is formed on the outer peripheral side of the inclined outer peripheral surface 193b1 of the swing gear support portion 193b on the upper steering shaft 2 side.

  The fourth gear support portion 193c has a substantially cylindrical shape with a shaft hole formed in the center, and is integrally coupled to the swinging gear support portion 193b on the lower steering shaft 4 side. An inner ring of a deep groove ball bearing supported on the inner peripheral surface of the inner diameter support portion 192b of the fourth gear 192 is fitted to the outer peripheral surface of the fourth gear support portion 193c. That is, the inclined shaft 193 is rotatable relative to the fourth gear 192.

(B4) Oscillating gear 194
The swing gear 194 will be described with reference to FIG. The swing gear 194 includes an inner ring portion 194a, a plurality of rollers 194b, and an outer ring gear portion 194c. The inner ring portion 194a has a substantially cylindrical shape, and the inner peripheral side is press-fitted to the inclined outer peripheral surface 193b1 of the swinging gear support portion 193b of the inclined shaft 193. Further, the end surface of the inner ring portion 194a on the upper steering shaft 2 side is in contact with a contact portion 193b2 of the swinging gear support portion 193b of the inclined shaft 193. Furthermore, a substantially arc-shaped circumferential groove (not shown) is formed on the outer peripheral surface of the inner ring portion 194a.

  The roller 194b has a spherical shape, and is disposed so as to be able to roll in the circumferential groove of the inner ring portion 194a. The outer ring gear portion (second gear, third gear) 194c has a substantially cylindrical shape, and a substantially arc-shaped circumferential groove (not shown) in which the roller 194b can roll is formed on the inner peripheral surface. . And this outer ring | wheel gear part 194c is arrange | positioned through the roller 194b on the outer peripheral side of the inner ring part 194a. That is, the outer ring gear portion 194c is rotatable about the rotation axis X2 (shown in FIG. 4) with respect to the inner ring portion 194a.

  Further, gears are formed on both end faces of the outer ring gear portion 194c. Specifically, a second gear (second tooth) having n2 teeth is formed on the end surface of the outer ring gear portion 194c on the upper steering shaft 2 side. A part of the second gear (upper side portion in FIG. 2) can mesh with the first roller gear 191 b of the first gear 191. A third gear (third tooth) having n3 teeth is formed on the end surface of the outer ring gear portion 194c on the lower steering shaft 4 side. A part of the third gear (the lower side portion in FIG. 2) can mesh with the fourth roller gear 192 d of the fourth gear 192.

(B5) Axial pressing spring 195
The axial pressing spring 195 has a disc spring having an outer diameter slightly smaller than the inner diameter of the second housing 12 and an inner diameter larger than the inner ring of the angular ball bearing supported on the inner peripheral surface of the second housing 12. The axial pressing spring 195 has one axial end abutting against the outermost end surface of the third housing 13 on the upper steering shaft 2 side, and the other axial end is supported by the inner peripheral surface of the second housing 12. The outer ring of the angular ball bearing is in contact with the lower steering shaft 4 side. That is, the axial pressing spring 195 presses the outer ring of the angular ball bearing against the third housing 13 toward the upper steering shaft 2 side. As a result, the inner ring of the angular ball bearing is pressed toward the upper steering shaft 2 side. Furthermore, since the inner ring of the angular ball bearing is in contact with the angular ball bearing contact portion 192c of the fourth gear 192, the fourth gear 192 is pressed toward the upper steering shaft 2. That is, the axial pressing spring 195 presses the fourth gear 192 against the third housing 13 toward the upper steering shaft 2 side, that is, the swinging gear 194 side.

(B6) Positional relationship between the first gear 191, the fourth gear 192, and the rocking gear 194 Here, with respect to the positional relationship between the first gear 191, the fourth gear 192, and the rocking gear 194, refer to FIG. Further details will be described. FIG. 5 is a view for explaining the positional relationship between the first gear 191, the fourth gear 192, and the swing gear 194, and corresponds to the axial sectional view of FIG. 2.

  As shown in FIG. 5, the center of the first spherical surface (first common spherical surface) passing through the pitch circle of the first roller gear 191b of the first gear 191 and the pitch circle of the second gear of the rocking gear 194 is O1. Further, the center of the second spherical surface (second common spherical surface) passing through the pitch circle of the fourth roller gear 192d of the fourth gear 192 and the pitch circle of the third gear of the rocking gear 194 is also O1. That is, the first gear 191, the fourth gear 192, and the swing gear 194 are formed and arranged so that the center of the first spherical surface coincides with the center of the second spherical surface.

(C) Operation of Reducer 19 Next, the operation of the reducer 19 having the above-described configuration will be described. Here, in order to facilitate the description of the operation of the speed reducer 19, a case will be described in which the housings 11 to 13 are fixed and the motor shaft 143 rotates with respect to the housings 11 to 13.

  First, the rotation of the motor shaft 143 that rotates relative to the housings 11 to 13 is input to the speed reducer 19. When the motor shaft 143 rotates with respect to the housings 11 to 13, the inclined shaft 193 integrally connected to the motor shaft 143 rotates integrally. At this time, the swinging gear support portion 193b of the tilt shaft 193 operates to swing the neck. Here, since the first gear 191 is fixed to the second housing 12, the inclined shaft 193 rotates with respect to the second housing 12.

  When the swinging gear support portion 193b swings its head by the rotation of the tilt shaft 193, the swinging gear 194 is rotatably supported on the tilted outer peripheral surface 193b1 of the swinging gear support portion 193b. The outer ring gear portion 194c swings as if it is just before the stop. The operation of the outer ring gear portion 194c of the swing gear 194 is called Coriolis motion.

  Then, when the outer ring gear portion 194c of the swing gear 194 performs Coriolis motion, the second gear of the swing gear 194 is changed to the first roller gear 191b, and the third gear of the swing gear 194 is changed to the fourth roller gear. 192d is meshed with each other. Then, the first gear 191 is swung with respect to the first gear 191 by an amount corresponding to the tooth number difference between the number n1 of the first roller gear 191b and the number n2 of the second gear of the outer gear 194c of the rocking gear 194. The outer ring gear portion 194c of 194 rotates. Further, the outer ring gear portion 194c of the oscillating gear 194 corresponds to the difference between the number of teeth n4 of the fourth roller gear 194d and the number of teeth n3 of the third gear of the outer ring gear portion 194c of the oscillating gear 194. In contrast, the fourth gear 192 rotates.

  For example, when the number of teeth n1 of the first gear 191 is 100, the number of teeth n2 of the second gear of the outer ring gear portion 194c of the swing gear 194 is 101, and the motor shaft 143 rotates once in the forward direction. The outer ring gear portion 194 c of the swing gear 194 rotates forward by 1/100 with respect to the motor shaft 143. Further, when the number of teeth n1 of the first gear 191 is 100 and the number of teeth n2 of the second gear of the outer ring gear portion 194c of the swing gear 194 is 99, and the motor shaft 143 makes one rotation in the forward direction. In this case, the outer ring gear portion 194 c of the swing gear 194 rotates reversely by 1/100 with respect to the motor shaft 143.

  Further, for example, when the number of teeth n3 of the third gear of the outer ring gear portion 194c of the swinging gear 194 is 100 and the number of teeth n4 of the fourth gear 192 is 101, the motor shaft 143 rotates once in the forward direction. In this case, the fourth gear 192 rotates forward by 1/100 with respect to the motor shaft 143. Further, when the number of teeth n3 of the third gear of the outer ring gear portion 194c of the swinging gear 194 is 100 and the number of teeth n4 of the fourth gear 192 is 99, and the motor shaft 143 rotates once in the forward direction. The fourth gear 192 rotates reversely by 1/100 with respect to the motor shaft 143.

  That is, when the motor shaft 143 makes one rotation, the reduction ratio R, which is the number of rotations of the lower steering shaft 4, is expressed by the following equation (1). That is, for example, when the number of teeth is about 100, the reduction ratio is about 2%.

  Since the fourth gear 192 is pressed against the third housing 13 by the axial pressing spring 195 toward the swing gear 194, the second gear 194c of the outer ring gear portion 194c of the first gear 191 and the swing gear 194 is used. The meshing with the gear and the meshing with the second gear of the outer ring gear portion 194c of the fourth gear 192 and the swing gear 194 can be made very good. That is, the axial play can be reduced by the axial pressing spring 195. As a result, it is possible to greatly reduce the noise and vibration caused by the gear backlash.

(3) Others In the above embodiment, the axial pressing spring 195 is disposed so as to press the outer ring of the angular ball bearing against the third housing 13 toward the upper steering shaft 2 side, but is not limited thereto. Absent. For example, the axial pressure spring 195 is disposed between the third housing 13 and the fourth gear 192 in the axial direction, and directly presses the fourth gear 192 toward the swing gear 194 against the third housing 13. You may do it. The axial direction pressing spring 195 may be disposed between the lower steering shaft 4 and the fourth gear 192 in the axial direction so as to directly press the fourth gear 192 against the lower steering shaft 4. Further, the axial direction pressing spring 195 is disposed between the second housing 12 and the first gear 191 so as to press the first gear 191 against the second housing 12 toward the swinging gear 194 side. Also good.

  Further, instead of using the axial pressing spring 195 as the axial force applying member, the third housing 13 itself can be used as the axial force applying member. Specifically, the end surface on the upper steering shaft 2 side of the third housing 13 may be pressed against the end surface on the lower steering shaft 4 side of the outer ring of the angular ball bearing toward the swing gear 194 side. Alternatively, the end surface of the third housing 13 on the upper steering shaft 2 side may be pressed directly against the end surface of the fourth gear 192 on the lower steering shaft 4 side toward the swing gear 194 side.

  Further, although the angular ball bearing is disposed between the inner peripheral surface of the third housing 13 and the outer peripheral surface of the fourth gear 192, the present invention is not limited to this. The bearing may be any bearing that can be loaded with an axial load.

It is a figure which shows the whole structure of the power steering device for vehicles. An axial sectional view of the steering angle ratio variable unit 3 is shown. An axial sectional view of the fourth gear 192 is shown. An axial sectional view of the inclined shaft 193 is shown. It is a figure explaining the positional relationship of the 1st gearwheel 191, the 4th gearwheel 192, and the rocking | fluctuation gearwheel 194. FIG.

Explanation of symbols

1: Steering wheel, 2: Upper steering shaft, 3: Steering angle ratio variable unit, 4: Lower steering shaft, 5: Electric power steering device, 11: First housing, 12: Second housing, 13: Third housing, 14: Motor (steering angle ratio variable motor), 15: Locking device, 16: Angle sensor, 17: Spiral cable, 18: Rubber coupling, 19: Reducer, 141: Motor housing, 142: Stator, 143: Motor shaft (Motor output shaft), 151: lock holder, 152: lock lever, 171: housing, 172: inner cylinder, 173: flexible flat cable, 191: first gear, 192: fourth gear, 193: inclined shaft, 194 : Oscillating gear, 195: Axial pressing spring ( (Axial force applying member, pressing member)

Claims (7)

An upper steering shaft connected to the steering wheel and transmitting a steering angle of the steering wheel;
A rudder angle ratio variable motor that is arranged substantially coaxially with the upper steering shaft and capable of rotating a motor output shaft relative to the upper steering shaft;
A speed reducer connected to the motor output shaft and outputting a turning angle with a reduced motor rotation angle of the motor output shaft;
A lower steering shaft that transmits the steered angle output from the speed reducer to the steered wheels;
With
In the steering angle ratio variable steering device that varies the steering angle ratio of the steering angle to the steering angle,
The speed reducer is
A first gear that is rotationally restrained by the upper steering shaft and has first teeth with n1 teeth formed on the end face;
A fourth gear having rotation-constrained rotation on the lower steering shaft and having fourth teeth with a number of teeth n4 formed on an end surface facing the end surface of the first gear;
An inclined shaft formed on an outer peripheral side with an inclined surface fixed to the motor output shaft and having an inclined rotation shaft that is inclined at a predetermined angle with respect to the rotation shaft of the motor output shaft;
A second gear between the first gear and the fourth gear, rotatably supported on the inclined surface, meshed with the first gear and having second teeth of n2 on the end face; A third gear that meshes with the fourth gear and has third teeth with n3 teeth formed on the end face; a center point of a first common spherical surface that passes through each pitch circle of the first gear and the second gear; A swing gear in which the center point of the second common spherical surface passing through each pitch circle of the third gear and the fourth gear coincides;
A steering angle ratio variable steering apparatus comprising:   Furthermore, at least one of the first gear and the fourth gear with respect to the upper steering shaft, the lower steering shaft, the upper steering shaft, or the housing fixedly disposed on the lower steering shaft, The steering angle ratio variable steering apparatus according to claim 1, further comprising an axial force applying member that applies an axial force to the wheel.   The axial force applying member is a spring that presses the upper steering shaft or the lower steering shaft or the housing at one end in the axial direction and presses the first gear or the fourth gear at the other end in the axial direction. The steering angle ratio variable steering apparatus according to claim 2,   The axial force applying member is a screwing member that is screwed to the upper steering shaft, the lower steering shaft, or the housing so as to be movable in the axial direction, and that one end side presses the first gear or the fourth gear. The steering angle ratio variable steering apparatus according to claim 2, wherein the steering angle ratio variable steering apparatus is provided. The axial force applying member is
And at least one of an outer ring and an inner ring fixed to the upper steering shaft or the housing fixedly disposed on the upper steering shaft, and one of an outer ring and an inner ring fixed to the fourth gear. A bearing capable of loading an axial load in one direction;
The outer ring of the bearing is pressed against the fourth gear side against the upper steering shaft or the housing, and the axial force toward the swing gear side against the fourth gear against the upper steering shaft or the housing. A pressing member for providing
The steering angle ratio variable steering apparatus according to claim 2, wherein:   The steering angle according to any one of claims 1 to 5, further comprising an engaging member that engages with an outer peripheral surface of the motor output shaft and engages with an inner peripheral surface of the inclined shaft. Variable ratio steering device.   The steering angle ratio variable steering apparatus according to any one of claims 1 to 5, wherein the tilt shaft is integrally formed with the motor output shaft.

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