JP4055001B2 - Reduction ratio variable power steering system - Google Patents

Description

  The present invention relates to a power steering apparatus that decelerates rotation of a steering wheel by a steering gear, and amplifies a steering input acting on the steering wheel by a servo mechanism and transmits it to a steered wheel.

When the turning angle of the steering wheel is small, the reduction ratio of the steering gear may be reduced to improve the cutting of the steering wheel. When the turning angle is increased, the reduction ratio may be increased to facilitate operation. Further, when the steering angle of the steering wheel is small and the steering angle of the steering wheel is small, the steering gear reduction ratio is increased to improve the neutral stability of the steering wheel. Furthermore, it is desirable to reduce the steering angle by reducing the reduction ratio considerably in garage storage. In order to deal with these problems, in a power steering apparatus that decelerates the rotation of the handle by the steering gear and amplifies the steering input acting on the handle by the servo mechanism and transmits it to the steered wheel, the handle-side shaft connected to the handle Japanese Patent Laid-Open No. 60-209362 discloses a variable reduction ratio type power steering apparatus in which the rotation ratio between the servo valve device and the input shaft of the servo valve device is variable. In this conventional device, the handle side shaft and the gear side shaft, which is the input shaft of the servo valve device, are supported by bearings at one location on the housing, and the handle side shaft is supported by a torsion bar pinned in the shaft hole of the gear side shaft. It is centered and supported coaxially. A first sun gear is spline coupled to the handle side shaft, and a second sun gear having a different number of teeth from the first sun gear is spline coupled to the gear side shaft. And the planet body in which the 1st and 2nd planetary gear which meshes with the 1st and 2nd sun gears respectively was formed was rotatably supported by the support shaft, and both ends of the support shaft were supported by the carrier. The carrier is rotatably supported by the handle side shaft and the gear side shaft, and the rotation ratio between the handle side shaft and the gear side shaft is changed by rotating the worm meshed with the worm gear engraved on the outer periphery of the carrier by the motor. It is supposed to be.
JP-A-60-209362 (pages 2, 3 and 1)

  In the variable reduction ratio type power steering apparatus, the handle-side shaft and the gear-side shaft are each supported by a bearing at one location on the housing, and the handle-side shaft is centered by a torsion bar pinned to the shaft hole of the gear-side shaft. Therefore, it is difficult to secure the concentricity between the handle side shaft and the gear side shaft due to misalignment between the torsion bar and the gear side shaft, and at the tip of both shafts. The mutual support rigidity is low, and there is a possibility that the rotation center of the first and second sun gears is displaced and smooth rotation transmission cannot be performed between the sun gear and the planetary gear. Further, since the carrier is rotationally driven by a worm gear engraved on the outer peripheral surface, the carrier is displaced by receiving a radial force, and the planetary gear is displaced so that smooth rotation transmission with the sun gear may not be performed. . Further, a worm gear is engraved on the outer periphery of the carrier on which the planets on which the first and second planetary gears meshed with the first and second sun gears, respectively, are supported, and the worm gear is fitted to the output shaft of the motor. Since the worm is meshed, the degree of freedom in assembling becomes small, and assembling and adjusting operations become difficult. Further, since the first and second sun gears are rotationally connected only through the first and second planetary gears, the handle side shaft is free to play with respect to the gear side shaft due to the backlash of the gear, and the neutral position of the handle is There is a problem that rigidity is lowered and steering feeling is lowered.

  The present invention has been made in order to solve the conventional problems, and it is an object of the present invention to provide a reduction gear ratio variable power steering apparatus capable of smooth rotation transmission.

According to a first aspect of the present invention, there is provided a power steering apparatus that decelerates rotation of a handle by a steering gear and amplifies a steering force acting on the handle by a servo mechanism and transmits the steering force to a steered wheel. A handle-side shaft connected to the steering gear and a gear-side shaft connected to the steering gear are rotatably supported on the housing on a central axis, and the handle-side shaft and the gear-side shaft are opposed to each other at a radius of the opposite end. The first and second sun gears having slightly different number of teeth are provided at opposite shaft end portions of the shafts so as to be relatively rotatable around the central axis via a bearing for supporting a directional load. A carrier that supports the first and second planetary gears that mesh with the first and second sun gears and rotate integrally is supported to be rotatable about the central axis. In the speed reduction ratio variable type power steering device for changing the reduction ratio by driving rotating the carrier by the motor, a shaft end portion facing the handle side shaft and the gear-side shaft by interposing a bearing for supporting the radial load A small-diameter portion extending along the central axis is protruded from one of the opposing shaft ends of the handle-side shaft and the gear-side shaft in order to fit in a relatively rotatable manner around the central axis. A bearing for supporting the small diameter portion is provided on the other end of the shaft, and the small diameter portion is engaged with the second planetary gear supported by the carrier in a second sun gear provided on the gear side shaft. When the tip of the small-diameter portion is inserted into the opening end of the bearing, the first sun gear provided on the handle-side shaft and the carrier are supported. Serial is the fact that the central axis line direction of the gap is formed between the first planetary gear.

According to a second aspect of the present invention, there is provided a structural feature of the first aspect of the present invention, wherein the rotating body rotatably coupled to the motor is supported alongside the carrier so as to be rotatable about the central axis, and the rotating body and the carrier are supported. Are engaged so as to be able to transmit rotation, and the carrier is rotationally driven by the motor through the rotating body to change the reduction ratio.

The structural feature of the invention according to claim 3 is that, in claim 2 , the gear side shaft is supported by the housing at at least two locations spaced apart in the central axis direction, and the handle side shaft is attached to the housing. This is because it was supported by bearings at one place.

The structural feature of the invention according to claim 4 is that, in claim 3 , the rotating body is supported on the gear side shaft.

The structural feature of the invention according to claim 5 is that in any one of claims 1 to 4 , the handle side shaft is connected to the handle via the servo mechanism.

In the invention according to claim 1 configured as described above, the first and second sun gears having slightly different number of teeth are integrally provided on the handle-side shaft connected to the handle and the gear-side shaft connected to the steering gear. The carrier for supporting the first and second planetary gears, which mesh with the first and second sun gears and rotate integrally, is supported so as to be rotatable about the central axis, and the opposite end portions of the handle side shaft and the gear side shaft are opposed to each other. A state where a small-diameter portion extending along the central axis is projected on one side, and a bearing for supporting the small-diameter portion is provided on the other side, and a second planetary gear supported by the carrier is engaged with a second sun gear provided on the gear-side shaft. When the small diameter portion is inserted into the bearing with the first sun gear provided on the handle side shaft and the cam when the tip of the small diameter portion is inserted into the open end of the bearing. Clearance of the central axis line direction is formed between the first planetary gear which is supported on A.
Thereby, the rotation of the handle side shaft is changed by the planetary gear mechanism according to the rotation of the carrier and transmitted to the gear side shaft, and the reduction ratio as the power steering device is changed. At this time, the shaft end portions of the handle-side shaft and the gear-side shaft that are opposed to each other are supported with high rigidity by bearings that support a radial load, and rotate relative to each other around the central axis, so that the rotation centers of the first and second sun gears Can be matched with high accuracy, and smooth rotation transmission can be performed between the sun gear and the planetary gear. Since the bearing supports the small-diameter portion before the first sun gear and the first planetary gear mesh with each other at the time of assembly, the first sun gear and the first planetary gear are installed with the concentricity of the handle side shaft and the gear side shaft established. It can be meshed, and the assembly work can be facilitated.

In the invention according to claim 2 configured as described above, the rotating body rotationally connected to the motor is supported so as to be rotatable around the same central axis along with the carrier so that the rotating body and the carrier can transmit rotation. Since they are engaged, the carrier can be prevented from being displaced by receiving a radial force due to the rotational driving force, and smooth rotation transmission can be performed between the planetary gear and the sun gear.

In the invention according to claim 3 configured as described above, the gear-side shaft is supported by the bearing at at least two locations spaced apart from each other in the central axis direction. The handle side shaft is supported by the bearing at one location on the housing, and the shaft end is supported by the bearing on the gear side shaft. Accordingly, the axial length of the apparatus can be shortened to reduce the size, and the handle side and gear side shaft can be supported with high rigidity.

In the invention according to claim 4 configured as described above, the rotating body that is rotationally driven by the motor and engages the carrier is supported by the gear-side shaft that is supported at two locations on the housing, so that high rigidity is maintained. Thus, the apparatus can be miniaturized.

In the invention according to claim 5 configured as described above, the handle-side shaft is connected to the handle via a servo mechanism, so an existing servo mechanism and a steering gear are used, and a planetary gear mechanism is added between them. By simply doing this, a reduction ratio variable power steering apparatus can be obtained.

Example 1
A variable reduction ratio type power steering apparatus according to a first embodiment of the present invention will be described below with reference to the drawings. 1 and 2, the variable speed reduction type power steering device 1 transmits the rotation of the handle 5 to the input shaft 4 of the servo valve device 3 of the hydraulic servo mechanism 2, and the rotation of the output shaft of the servo valve device 3 causes the planetary gear. The gear is shifted by the mechanism 6 and transmitted to the pinion shaft of the rack and pinion mechanism 7. Thereby, the rotation of the handle 5 is decelerated by the rack and pinion mechanism 7 which is a steering gear, and the steering force acting on the handle 5 is amplified by the servo mechanism 2 and transmitted to the steering wheel 8.

  The upper housing 9 and the lower housing 10 are connected by bolts to form a housing. A servo valve device 3 is accommodated in the upper housing 9, and a handle side shaft 11, which is an output shaft of the servo valve device 3, is supported on the upper housing 9 so as to be rotatable around the central axis O by a bearing 12. A rack and pinion mechanism 7 is housed in the lower housing 10, and a gear side shaft 13, which is a pinion shaft of the rack and pinion mechanism 7, can be rotated around the central axis O by bearings 14 and 15 at two locations separated in the direction of the central axis O. It is bearing. The handle side shaft 11 extends into a gear housing portion 9a formed on the upper housing 9 side of the lower housing 10, and a small diameter portion 11a projects from the shaft end. A bearing hole 13 a is formed at the shaft end of the gear side shaft 13 that faces the handle side shaft 11, and a small diameter portion 11 a is rotatably supported by the needle bearing 16 in the bearing hole 13 a. In this way, the opposite shaft ends of the handle-side shaft 11 and the gear-side shaft 13 have a high concentricity around the central axis O through a bearing for supporting a radial load, and can be relatively rotated with high rigidity. It is mated.

  A rotary valve 18 is formed on the input shaft 4 of the servo valve device 3. A sleeve 20 rotatably connected to the handle-side shaft 11 is fitted into the distribution hole 19 formed in the upper housing 9 so as to be rotatable around the central axis O, and the rotary valve 18 is inserted into the valve hole 21 formed in the sleeve 20. Are fitted around the central axis O so as to be rotatable. The servo valve device 3 is constituted by the rotary valve 18, the sleeve 20 and the like, and the A and B ports respectively connected to the left and right chambers of the cylinder device 30 according to the relative rotation of the rotary valve 18 and the sleeve 20 are the hydraulic pump 22 and The P and T ports connected to the tank 23 are connected. The input shaft 4 and the handle shaft 11 are coupled to both ends of the torsion bar 24, respectively, and when the input shaft 4 is in a free state without any steering input being applied to the handle 5, the P and T ports are communicated and A and B The rotary valve 18 is rotationally positioned relative to the sleeve 20 in a neutral position where no hydraulic pressure is generated in the port.

  A pinion 25 is formed between the bearings 14 and 15 on the gear side shaft 13, and a rack shaft 27 in which a rack 26 meshed with the pinion 25 is engraved is slidably mounted on the lower housing 10. As shown in FIG. 2, a cylinder tube 28 is fixed to the lower housing 10, and a piston 29 fixed to the rack shaft 27 is fitted to the cylinder tube 28 to constitute a cylinder device 30. A knuckle arm is connected to both projecting ends of the rack shaft 27 by a ball joint via a tie rod, and the steering wheel 8 is deflected by the axial movement of the rack shaft 27.

  In the gear housing portion 9a of the lower housing 10, a rotating body 33 that is rotationally driven by the planetary gear mechanism 6 and the motor 32 is stored side by side. First and second sun gears 34 and 35 having slightly different number of teeth of the planetary gear mechanism 6 are integrally provided at opposite shaft ends of the handle side shaft 11 and the gear side shaft 13. Plates 36a and 36b are loosely fitted to the gear side shaft 13 and the handle side shaft 11, and a plurality of (for example, three) planetary bodies 37 arranged at substantially equal angular intervals on the circumference are provided on the plates 36a and 36b. The bearings 38a and 36b are rotatably supported via bushes 39 by bearing shafts 38 supported at both ends. First and second planetary gears 40 and 41 are integrally formed on the coaxial line so that each planetary body 37 meshes with the first and second sun gears 34 and 35 and rotates integrally therewith. A carrier 36 that supports the first and second planetary gears 40 and 41 is constituted by the plates 36a and 36b, the support shaft 38, and the like. As an example, the number of teeth of the first and second sun gears 34 and 35 and the first and second planetary gears 40 and 41 is 20, 21, 21, and 20, respectively. At the bottom of the gear housing portion 9a, the rotating body 33 is supported by the gear side shaft 13 so as to be rotatable around the central axis O by a bearing 42 along with the carrier 36. A worm wheel 43 is engraved on the outer periphery of the rotating body 33, and the worm wheel 43 meshes with a worm 44 fitted to the output shaft of the motor 32 fixed to the lower housing 10. Each support shaft 38 passes through the plate 36a and fits into an engagement hole 33a formed in the side surface of the rotating body 42, and engages the rotating body 33 and the carrier 36 so as to transmit rotation.

  Next, the operation of the first embodiment will be described. When the handle 5 is rotated, the rotary valve 18 and the sleeve 20 are rotated relative to each other by twisting the torsion bar 24, and the pressure oil supplied from the hydraulic pump 22 is changed from the A or B port to the cylinder according to the rotation direction of the handle 5. The cylinder 30 is supplied to the cylinder left chamber 28a or the right chamber 28b of the device 30, and the rack shaft 27 is pivoted to deflect the steering wheel 8. At this time, when the handle side shaft 11 is rotated n1, the gear side shaft 13 is shifted by the planetary gear mechanism 6 and rotated n2. At this time, the rotation ratio n2 / n1 between the gear side shaft 13 and the handle side shaft 11 is n2 / n1 = r + n3 / n1 (1-r), where n3 is the rotation of the carrier 36. Here, r is the rotation ratio r when the carrier 36 is stationary, assuming that the number of teeth of the first and second sun gears 34, 35 and the first and second planetary gears 40, 41 is z1, z2, z3, z4. = N2 / n1 = z1 / z3 / z2 / z4. Therefore, when the number of teeth is as in the above example, r = 20 · 20/21 · 21 = 0.91. When the carrier 36 is rotated in the same direction as the handle 5, the rotation number n3 The rotation ratio n2 / n1 is increased and acts in the direction of decreasing the reduction ratio of the steering gear, and the reduction ratio of the power steering apparatus as a whole is reduced. When the carrier 36 is rotated in the direction opposite to the handle 5, the reduction ratio of the entire power steering apparatus is increased. When the handle 5 is turned off, the electronic control unit (not shown) calculates the rotation direction and the number of rotations of the motor 32 so that the reduction ratio of the power steering apparatus as a whole becomes the optimum reduction ratio for the traveling state of the vehicle. The motor 32 is rotated.

  At this time, the opposite shaft end portions of the handle side shaft 11 and the gear side shaft 13 are provided with a high concentricity around the central axis O through a needle bearing 16 for supporting a radial load, and can be relatively rotated with high rigidity. Therefore, the rotation centers of the first and second sun gears 34 and 35 coincide with each other with high accuracy, and smooth rotation transmission can be performed between the sun gear and the planetary gear. Further, when the rotating body 33 is rotated by the motor 32, the support shaft 38 engaged with the rotating body 33 is rotationally driven, and the radial component of the rotational force that rotates the carrier 36 is canceled out. Accordingly, the first and second planetary gears 40 and 41 can smoothly mesh with the first and second sun gears 34 and 35 without receiving a radial force. In particular, the plates 36a and 36b are loosely fitted to the first and second sun gears 34 and 35, and a plurality of planets 37 are supported on the plates 36a and 36b by the support shaft 38 at equal angular intervals on the circumference. In the carrier 36 described above, the first and second planetary gears 40 and 41 formed on each planetary body 37 are meshed with the first and second sun gears 34 and 35, respectively, and the carrier 36 is rotatably supported. Since the carrier 36 is not supported by the housing with high rigidity by a bearing, it is effective to obtain a smooth engagement by rotationally driving the carrier 36 so that no radial force acts.

(Example 2)
Next, a second embodiment will be described. Since the configuration of the variable speed reduction type power steering apparatus of the second embodiment is almost the same as that of the first embodiment, the same reference numerals are assigned to the same components, and detailed description is omitted. Only the differences will be explained. As shown in FIG. 3, in the second embodiment, a sliding hole 13b is continuously drilled in the bearing hole 13a at the shaft end of the gear side shaft 13, and the friction body 45 slides in the sliding hole 13b. The friction body 45 is pressed against the end surface of the small diameter portion 11 a of the handle side shaft 11 by the spring force of the compression spring 46. In this manner, the friction body 45 that resists relative rotation is interposed between the handle-side shaft 11 and the gear-side shaft 13. Note that the friction body may be interposed between the opposing side surfaces of the first and second sun gears 34 and 35 .

  In the second embodiment, when the handle 5 is turned and the gear side shaft 13 is rotated by the handle side shaft 11 by meshing between the first and second sun gears 34 and 35 and the first and second planetary gears 40 and 41. Since the friction body 45 is pressed against the small diameter portion 11a by the spring force of the compression spring 46, it becomes a resistance against the relative rotation between the handle side shaft 11 and the gear side shaft 13, and the play due to the backlash of the gear is reduced. Improves the steering feeling and increases the rigidity when the steering wheel is neutral.

  In the above embodiment, the carrier 36 is configured by supporting a plurality of planets 37 on the plates 36a, 36b loosely fitted to the first and second sun gears 34, 35 by the support shaft 38 at substantially equal angular intervals on the circumference. The carrier 36 is rotatably supported by meshing the first and second planetary gears 40 and 41 formed on each planetary body 37 with the first and second sun gears 34 and 35, respectively. It may be supported rotatably and may support one or more planetary bodies on the carrier.

In the above embodiment, the planetary gear mechanism 5 is arranged at the rear stage of the servo valve device 3 by setting the output shaft of the servo valve device 3 to the handle side shaft 11, but the gear side shaft 13 is replaced by the servo valve device. The planetary gear mechanism 5 may be arranged at the front stage of the servo valve device 3 by using the output shaft 3.

  In the above embodiment, the power steering device operates the servo valve device by rotating the handle to supply and discharge the pressure oil to and from the cylinder device to move the rack shaft, but the electric servomotor is driven according to the rotation of the handle. And the rack shaft may be axially moved via a ball screw mechanism. Further, a sector gear may be used as the steering gear instead of the rack and pinion mechanism.

(Example 3)
Next, a third embodiment will be described. The configuration of the variable gear ratio variable power steering apparatus of the third embodiment is the same as that of the second embodiment, except for the dimensional relationship of the components. That is, as shown in FIG. 4, the shaft length of the small diameter portion 11a protruding from the shaft end of the handle side shaft 11 is L1, and the second sun gear 35, the planetary gears 40, 41, etc. are assembled to the lower housing 10. In this state, when the distance from the shaft end of the gear side shaft 13 to the lower housing 10 opening side end surface of the first planetary gear 40 is L2, the length L1 is made longer than the length L2. With such a dimensional relationship, the first sun gear 34 provided on the handle-side shaft 11 and the first planetary gear 40 supported by the carrier 36 when the tip of the small diameter portion 11a is inserted into the opening end of the bearing hole 13a. A gap in the central axis direction is formed between the two. The procedure of assembly work will be described below. Assembling is performed separately for the upper housing 9 and the lower housing 10, and finally the upper housing 9 and the lower housing 10 are integrated.

   On the upper housing 9 side, after the torsion bar 24 is press-fitted to the handle side shaft 11, the neutral position of the input shaft 4 and the handle side shaft 11 is adjusted, and the torsion bar 24 and the input shaft 4 are pin-coupled. The servo valve device 3 is assembled. Then, the assembled servo valve device 3 is supported and accommodated in the upper housing 9 by a bearing 12.

   On the other hand, on the lower housing 10 side, a rotating body 33 is rotatably mounted on the gear side shaft 13 via a bearing 42, and a support shaft 38 is inserted into an engagement hole 33a of the rotating body 33, and the planetary body 37 and the plates 36a, 36b. The planetary gear mechanism 6 composed of, for example, is fitted in the assembled state. In a state where the planetary gear mechanism 6 and the rotating body 33 are assembled, the gear-side shaft 13 is supported and accommodated in the lower housing 10 by bearings 15 and 14 so as to be relatively rotatable. Thereafter, the rack and pinion mechanism 7 including the rack shaft 27 is assembled to the pinion 25 formed on the gear side shaft 13, the worm 44 is engaged with the worm wheel 43 of the rotating body 33, and the motor 32 is connected to the lower housing 10. Fixed to.

   As described above, the servo valve device 3 is accommodated in the upper housing 9, and the planetary gear mechanism 6 and the rack and pinion mechanism 7 are accommodated in the lower housing 10. Thereafter, the compression spring 46 and the friction sliding body 45 are accommodated in the sliding hole 13b of the gear side shaft 13 assembled in the lower housing 10, and the needle bearing 16 is accommodated in the bearing hole 13a. Then, the small diameter portion 11a of the handle side shaft 11 housed in the upper housing 9 is inserted into the bearing hole 13a, and the first planetary gear 40 of the planetary gear mechanism 6 and the first sun gear 34 of the handle side shaft 11 are engaged. At this time, as shown in FIG. 4, the small-diameter portion 11 a is supported by the needle bearing 16 before the first planetary gear 40 and the first sun gear 34 are engaged with each other. As a result, the first planetary gear 40 and the first sun gear 34 can be engaged with each other after the handle-side shaft 11 and the gear-side shaft 13 are aligned on the rotation axis O. It becomes easy. In particular, when the first planetary gear 40 and the first sun gear 34 are helical gears, the meshing operation is further facilitated.

   When the first planetary gear 40 and the first sun gear 34 are engaged with each other, the small diameter portion 11a is inserted into the sliding hole 13b and comes into contact with the friction sliding body 45, and the compression spring 46 is compressed to compress the small diameter portion 11a and the friction sliding body 45. Is in close contact. Thereafter, the upper housing 9 and the lower housing 10 are fixed with bolts 47 to complete the assembling work.

   In the embodiment shown in FIG. 4 described above, an example in which the sliding shaft 13b is formed in the gear side shaft 13 following the bearing hole 13a and the friction sliding body 45 is used together is shown. The moving body 13b is not necessarily used together. Alternatively, the small diameter portion 11 a may be formed in the gear side shaft 13, the bearing hole 13 a may be formed in the handle side shaft 11, and the gear side shaft 13 may be supported by the handle side shaft 11.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view of a variable reduction ratio type power steering apparatus according to a first embodiment. Sectional drawing cut | disconnected along the II-II line | wire of FIG. The longitudinal cross-sectional view of 2nd Embodiment. The longitudinal cross-sectional view explaining the assembly | attachment state of the upper housing and lower housing which concern on 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Variable reduction ratio type power steering device, 2 ... Hydraulic servo mechanism, 3 ... Servo valve device, 4 ... Input shaft, 5 ... Handle, 6 ... Planetary gear mechanism, 7 ... Rack and pinion mechanism (steering gear), 8 ... Operation Direction wheel, 9 ... Upper housing, 10 ... Lower housing, 10a ... Gear housing, 11 ... Handle side shaft, 12, 14, 15, 42 ... Bearing, 13 ... Gear side shaft, 16 ... Needle bearing, 18 ... Rotary valve , 22 ... hydraulic pump, 24 ... torsion bar, 27 ... rack shaft, 30 ... cylinder device, 32 ... motor, 33 ... rotating body, 34, 35 ... first and second sun gears, 36 ... carrier, 37 ... planetary body, 38 ... bearing shaft, 40, 41 ... first and second planetary gears, 43 ... worm wheel, 44 ... worm, 45 ... friction body, 46 ... compression spring, L ... of small diameter portion length, the distance from the shaft end of L2 ... gear-side shaft 13 until the lower housing 10 opening-side end face of the first planetary gear 40.

Claims (5)

In a power steering apparatus that decelerates rotation of a steering wheel by a steering gear and amplifies a steering force acting on the steering wheel by a servo mechanism and transmits the steering force to a steered wheel, a steering wheel side shaft coupled to the steering wheel, and the steering gear The connected gear side shaft is rotatably supported on a central axis on the housing, and the shaft side opposite to the handle side shaft and the gear side shaft is interposed via a bearing for supporting a radial load. The first and second sun gears having slightly different number of teeth are provided at opposite shaft end portions of the shafts so as to be relatively rotatable around each other, and mesh with the first and second sun gears to rotate integrally. A carrier for supporting the first and second planetary gears is rotatably supported around the central axis, and the carrier is driven to rotate by a motor. In the speed reduction ratio variable type power steering device for changing the reduction ratio,
The handle-side shaft and the gear-side shaft are fitted to the handle-side shaft and the gear-side shaft so as to be relatively rotatable around the central axis via a bearing for supporting a radial load. A small-diameter portion extending along the central axis is provided on one of the opposite shaft end portions of the shaft, and a bearing for supporting the small-diameter portion is provided on the other end of the shaft ends. When the small diameter portion is inserted into the bearing in a state where the second planetary gear supported by the carrier is engaged with the second sun gear, the handle when the tip of the small diameter portion is inserted into the opening end of the bearing A reduction ratio in which a gap in the direction of the central axis is formed between a first sun gear provided on a side shaft and the first planetary gear supported by the carrier Strange-type power steering system. 2. The rotating body rotatably coupled to the motor according to claim 1 , wherein the rotating body is rotatably supported around the central axis along with the carrier, and the rotating body and the carrier are engaged so as to be able to transmit rotation. A reduction ratio variable power steering apparatus, wherein the reduction ratio is changed by rotationally driving the carrier via the rotating body. 3. The reduction gear according to claim 2 , wherein the gear side shaft is supported by a bearing at at least two locations spaced apart from each other in the central axis direction on the housing, and the handle side shaft is supported by the bearing at one location on the housing. Ratio variable power steering device. 4. The variable speed reduction type power steering apparatus according to claim 3 , wherein the rotating body is supported on the gear side shaft. In any one of claims 1 to 4, the reduction gear ratio variable type power steering apparatus characterized by the handle-side shaft coupled to the handle via the servo mechanism.

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