JP2004249763A - Power steering device with variable reduction ratio - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power steering device equipped with variable reduction ratio embodied in a small and light construction capable of performing a smooth rotational transmission and assuring easy installation. <P>SOLUTION: The power steering device equipped with variable reduction ratio is structured so that a steering wheel side shaft 11 coupled with a steering wheel 5 and a gear side shaft 13 coupled with steering gears are borne rotatably by a housing on the center axis O. The first 34 and the second sun gear 35 having slightly different number of teeth are installed at the ends confronting of the two shafts 11 and 13, and pair of plates 36a and 36b are loosely fitted on the shafts 11 and 13, and an epicyclic body 37 whereon the first 40 and the second planetary gear 41 meshing with the sun gears 34 and 35 and rotating in a single piece are formed coaxially is borne rotatably by a shaft 38 whose two ends are borne by the plates 36a and 36b, and thereby, and the epicyclic body 37 is held rotatably on the sun gears 34 and 35. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a power steering device that reduces the rotation of a steering wheel by a steering gear, amplifies a steering input acting on the steering wheel by a servo mechanism, and transmits the amplified steering input to steered wheels.
[0002]
[Prior art]
When the steering angle of the steering wheel is small, the reduction ratio of the steering gear is reduced to improve the turning of the steering wheel, and when the steering angle is large, the reduction ratio may be increased to make the operation easier. In addition, the relationship between the steering wheel turning angle and the reduction ratio may be reversed from the above-described relationship to increase the steering gear reduction ratio when the steering wheel turning angle is small to improve the neutral stability of the steering wheel. In addition, it is desired to reduce the turning angle of the steering wheel by making the reduction ratio considerably small in a garage. In order to cope with the above, in a power steering device in which the rotation of the steering wheel is reduced by a steering gear and the steering input acting on the steering wheel is amplified by a servo mechanism and transmitted to the steered wheels, a steering shaft connected to the steering wheel is provided. Japanese Patent Application Laid-Open No. 60-209362 discloses a variable speed reduction type power steering device in which the rotation ratio between the motor and the input shaft of the servo valve device is made variable.
[0003]
In this conventional device, the handle shaft and the gear shaft, which is the input shaft of the servo valve device, are respectively supported on the housing by bearings at one point, and the handle shaft is provided by a torsion bar pinned to a shaft hole of the gear shaft. It is centered and coaxially supported on it. A first sun gear is spline-coupled to the handle 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. A planetary body having first and second planetary gears meshing with the first and second sun gears is rotatably supported by a support shaft, and both ends of the support shaft are supported by the carrier. The carrier is rotatably supported on the handle shaft and the gear shaft, and the worm meshing with the worm gear engraved on the outer periphery of the carrier is rotated by a motor to change the rotation ratio between the handle shaft and the gear shaft. It is supposed to be.
[0004]
[Patent Document 1]
JP-A-60-209362 (pages 2, 3; FIG. 1)
[0005]
[Problems to be solved by the invention]
In the variable reduction ratio power steering device, a worm gear is engraved on an outer periphery of a carrier on which a planetary body on which first and second planetary gears meshing with the first and second sun gears are formed is supported. Since the worm fitted to the output shaft is meshed, the degree of freedom in assembling is reduced, and assembling and adjusting work becomes difficult. Further, since the carrier is rotationally driven by the worm gear engraved on the outer peripheral surface, the carrier is displaced by receiving a radial force, and the position of the planetary gear is shifted, so that smooth rotation transmission with the sun gear may not be performed. . Further, since the worm gear and the bearing hole for the handle shaft are formed in the carrier, the processing of the carrier is complicated, and the processing needs to be performed with high precision.
[0006]
SUMMARY OF THE INVENTION The present invention has been made in order to solve the conventional problem, and it is an object of the present invention to provide a small and lightweight variable speed ratio variable power steering device capable of smoothly transmitting rotation and easy to assemble.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a structural feature of the invention according to claim 1 is that the rotation of the steering wheel is reduced by the steering gear, and the steering force acting on the steering wheel is amplified by the servo mechanism and transmitted to the steered wheels. In a power steering device, a handle shaft connected to a steering wheel and a gear shaft connected to a steering gear are rotatably supported on a housing on a central axis, and teeth are provided on opposite shaft ends of these shafts. First and second sun gears having slightly different numbers are provided, and a carrier that supports the first and second planetary gears that mesh with the first and second sun gears and rotate integrally therewith is rotatably supported around a central axis, The rotating body connected to the motor is supported so that it can rotate around the central axis alongside the carrier, and only the rotating force can be transmitted between the rotating body and the carrier. Engaged, it is to change the reduction ratio of the carrier driven to rotate via the rotating member by a motor.
[0008]
According to a second aspect of the present invention, there is provided a power steering device for reducing the rotation of a steering wheel by a steering gear and amplifying a steering force acting on the steering wheel by a servo mechanism and transmitting the amplified steering force to a steered wheel. The connected handle-side shaft and the gear-side shaft connected to the steering gear are rotatably supported on the housing on a central axis, and the first and second shafts having slightly different numbers of teeth are provided at opposite shaft ends of the shafts. A second sun gear is provided, a pair of plates are loosely fitted to both shafts, and first and second planetary gears meshing with the first and second sun gears respectively and integrally rotating are formed on a coaxial line with a pair of plates. The planetary body is rotatably supported on the first and second sun gears by rotatably supporting a support shaft having both ends supported thereon, and is rotated by the motor. The connected rotating body is juxtaposed to one of the pair of plates and supported so as to be rotatable around the central axis, the rotating body and one of the plates are engaged so as to be able to transmit only rotational force, and the rotating body is driven by a motor. To change the speed reduction ratio by driving the pair of plates via the rotary shaft.
[0009]
A structural feature of the invention according to claim 3 is that, in claim 2, the one plate and the rotating body are engaged by spline engagement.
[0010]
A structural feature of the invention according to claim 4 is that, in claim 2, one plate is engaged with the rotating body by engaging an engaging pin protruding from one plate with the rotating body. .
[0011]
A structural feature of the invention according to claim 5 is that, in claim 4, the engagement pin is formed by extending a support shaft for rotatably supporting the planetary body and projecting from the plate.
[0012]
The structural feature of the invention according to claim 6 is that, in any one of claims 1 to 5, the gear-side shaft is supported on the housing by a bearing at at least two places separated in the center axis direction, and the handle-side shaft is mounted on the housing. That is, the bearing was supported by the bearing at one place in the housing.
[0013]
A structural feature of the invention according to claim 7 is that, in claim 6, the rotating body is supported on the gear-side shaft.
[0014]
According to an eighth aspect of the present invention, in any one of the first to seventh aspects, the handle-side shaft is connected to the handle via a servo mechanism.
[0015]
[Action and Effect of the Invention]
In the invention according to claim 1 configured as described above, the first and second sun gears having slightly different numbers of teeth are integrally provided on the handle shaft connected to the handle and the gear shaft connected to the steering gear. A carrier that supports the first and second planetary gears, which mesh with the first and second sun gears and rotate integrally, is supported rotatably about the central axis. Thereby, the rotation of the handle shaft is changed by the planetary gear mechanism in accordance with the rotation of the carrier and transmitted to the gear shaft, so that the reduction ratio as the power steering device is changed. The rotating body rotatably connected to the motor is rotatably supported around the same central axis alongside the carrier, and the rotating body and the carrier are engaged so as to transmit only the rotational force. Displacement due to a radial force by the force can be prevented, and smooth rotation can be transmitted between the planetary gear and the sun gear.
[0016]
In the invention according to claim 2 configured as described above, the first and second sun gears having slightly different numbers of teeth are integrally provided on the handle-side shaft connected to the handle and the gear-side shaft connected to the steering gear. A pair of plates are loosely fitted to both shafts, and first and second planetary gears that mesh with the first and second sun gears and rotate integrally therewith are formed on a coaxial line. The planetary body is rotatably supported on the first and second sun gears by being rotatably supported on the bearing shaft. As a result, the rotation of the handle shaft is changed by the planetary gear mechanism according to the rotation of the pair of plates and transmitted to the gear shaft, thereby changing the reduction ratio as the power steering device. Then, a rotating body that is rotationally connected to the motor is juxtaposed to one of the pair of plates and supported so as to be rotatable around the central axis, and the rotating body and one of the plates are engaged so as to transmit only the rotational force. As a result, the planetary gear, the handle shaft, and the gear shaft can be prevented from being displaced by receiving a radial force due to the rotational driving force, and smooth rotation can be transmitted between the planetary gear and the sun gear. Further, since the carrier is not held by the bearing as in the related art, but is rotatably supported and held on the first and second sun gears, the degree of freedom in assembling is increased. This makes it possible to reduce the backlash due to the engagement of the planetary gear and the sun gear, and to facilitate the assembly.
[0017]
In the invention according to claim 3 configured as described above, since one of the plates and the rotating body are engaged by spline engagement, the engagement between the carrier and the rotating body is made strong, The rotating body and the carrier can be engaged so that only the rotational force can be transmitted to the rotating body.
[0018]
In the invention according to claim 4 configured as described above, the engaging plate protruding from one of the plates is engaged with the rotating body, so that one of the plates is engaged with the rotating body. The configured carrier and the rotating body can be easily engaged.
[0019]
In the invention according to claim 5 configured as described above, the engagement pin is formed by extending the support shaft that rotatably supports the planetary body and protruding from the plate, so that the conventionally used support pin is used. By processing the shaft and using it as a carrier driving member, it is possible to prevent an increase in the number of parts and suppress an increase in cost.
[0020]
In the invention according to claim 6 configured as described above, the gear-side shaft is supported by the bearing at at least two places separated in the center axis direction by the housing, and the handle-side shaft is supported by the bearing at one place on the housing. . This makes it possible to reduce the size of the device by shortening the length in the axial direction and to mount the handle-side shaft and the gear-side shaft with high rigidity.
[0021]
In the invention according to claim 7 configured as described above, since the rotating body that is driven to rotate by the motor and engages with the carrier is supported on the gear-side shaft that is supported by the housing at two locations, high rigidity is maintained. As a result, the size of the device can be reduced.
[0022]
In the invention according to claim 8 configured as described above, since the handle-side shaft is connected to the handle via the servo mechanism, an existing servo mechanism and a steering gear are used, and a planetary gear mechanism is added between the two. By simply doing so, it is possible to obtain a variable reduction ratio type power steering device.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a variable speed reduction type power steering apparatus according to a first embodiment of the present invention will be described with reference to the drawings. In FIGS. 1 and 2, in a variable speed reduction type power steering device 1, rotation of a handle 5 is transmitted to an input shaft 4 of a servo valve device 3 of a hydraulic servo mechanism 2, and rotation of an output shaft of the servo valve device 3 is a planetary gear. The speed is changed by the mechanism 6 and transmitted to the pinion shaft of the rack and pinion mechanism 7. Thus, the rotation of the handle 5 is reduced by the rack and pinion mechanism 7 serving as a steering gear, and the steering force acting on the handle 5 is amplified by the servo mechanism 2 and transmitted to the steered wheels 8.
[0024]
The upper housing 9 and the lower housing 10 are connected by bolts to form a housing. The servo valve device 3 is housed in the upper housing 9, and a handle shaft 11, which is an output shaft of the servo valve device 3, is rotatably supported on the upper housing 9 by a bearing 12 so as to be rotatable around a central axis O. The rack and pinion mechanism 7 is housed in the lower housing 10, and a gear shaft 13, which is a pinion shaft of the rack and pinion mechanism 7, is rotatably supported around the central axis O by bearings 14 and 15 separated in the direction of the central axis O. I have.
[0025]
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 shaft 11 is fitted into a storage hole 19 formed in the upper housing 9 so as to be rotatable around a central axis O, and a rotary valve 18 is fitted into a valve hole 21 formed in the sleeve 20. Are rotatably fitted around the central axis O. 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 28 a and 28 b of the cylinder device 30 according to the relative rotation of the rotary valve 18 and the sleeve 20 are hydraulically operated. The P and T ports are connected to the pump 22 and the tank 23, respectively. The input shaft 4 and the handle shaft 11 are respectively connected to both ends of the torsion bar 24. When the steering shaft is not actuated on the handle 5 and the input shaft 4 is in a free state, the P and T ports are connected and A and B are connected. The rotary valve 18 is rotationally positioned relative to the sleeve 20 at a neutral position where no hydraulic pressure is generated at the port.
[0026]
A pinion 25 is formed between the bearings 14 and 15 on the gear-side shaft 13, and a rack shaft 27 on which a rack 26 meshing 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 form a cylinder device 30. Knuckle arms are connected to both protruding ends of the rack shaft 27 via tie rods by ball joints, and the steered wheels 8 are deflected by the axial movement of the rack shaft 27.
[0027]
As shown in FIG. 1, a planetary gear mechanism 6 and a rotating body 33 driven to rotate by a motor 32 are housed side by side in a gear housing portion 10 a of the lower housing 10. First and second sun gears 34 and 35 in which the number of teeth of the planetary gear mechanism 6 is slightly different are integrally provided at opposite shaft ends of the handle shaft 11 and the gear shaft 13, respectively. A plurality (three in the present embodiment) of planets are loosely fitted to the gear-side shaft 13 and the handle-side shaft 11, and a pair of plates 36a and 36b are loosely fitted on the plates 36a and 36b. The body 37 is rotatably supported via bushes 39 by bearing shafts 38 supported at both ends by plates 36a and 36b. First and second planetary gears 40 and 41, which mesh with the first and second sun gears 34 and 35, respectively, and integrally rotate, are integrally formed on each planetary body 37 on a coaxial line. 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. The number of teeth of the first and second sun gears 34 and 35 and the first and second planetary gears 40 and 41 was 20, 21, 21, 20 as an example.
[0028]
At the bottom of the gear housing portion 10a, a rotating body 33 is supported on the gear-side shaft 13 by bearings 42, 42 so as to be rotatable around the central axis O alongside the plate 36a of the carrier 36. The rotating body 33 and the plate 36a are spline-engaged with a spline shaft 45 rotatably supported around the central axis O, and are engaged so as to transmit only rotational force. The spline shaft 45 formed in a cylindrical shape is fitted with a spline formed in the outer circumference with a spline hole formed in the rotating body 33 and the plate 36a with a little play, and is loosely fitted in the gear-side shaft 13. I have. 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 on an output shaft of the motor 32 fixed to the lower housing 10.
[0029]
Next, the operation of the first embodiment will be described. When the handle 5 is turned, 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 supplied from the A or B port to the cylinder according to the rotation direction of the handle 5. It is supplied to the cylinder left chamber 28a or the right chamber 28b of the device 30, and the rack shaft 27 is axially moved to deflect the steered wheels 8. At this time, when the handle shaft 11 is rotated n1 times, the gear shaft 13 is shifted by the planetary gear mechanism 6 and rotated n2 times. 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, assuming that 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 z1, z2, z3 and z4, r is the rotation ratio r when the carrier 36 is stationary. = N2 / n1 = z1 / z3 / z2 / z4. Therefore, when the number of teeth is as in the above-described example, r = 20 · 20/21 · 21 = 0.91, and when the carrier 36 is rotated in the same direction as the handle 5, the rotation speed is determined according to the rotation speed n 3. The rotation ratio n2 / n1 is increased and acts in a direction to decrease the reduction ratio of the steering gear, so that the reduction ratio of the entire power steering device is reduced. When the carrier 36 is rotated in a direction opposite to that of the steering wheel 5, the reduction ratio of the power steering device as a whole increases. When the steering wheel 5 is turned, 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 device as a whole becomes an optimal reduction ratio for the running state of the vehicle. To rotate the motor 32.
[0030]
When the rotating body 33 is rotated by the motor 32, the spline formed on the outer periphery of the spline shaft 45 and the rotating body 33 and the spline holes formed in the plate 36a are meshed with each other. Only the rotational force is transmitted so as to be transmitted, and the rotational force is applied, so that the radial component of the rotational force for rotating the carrier 36 is canceled. Thus, the carrier 36, the handle shaft 11, and the gear shaft 13 can be prevented from being displaced by receiving a radial force due to the rotational driving force, and the first and second planetary gears 40, 41 receive the radial force. It is possible to smoothly mesh with the first and second sun gears 34 and 35 without any problem. In particular, the plates 36a, 36b are loosely fitted to the first and second sun gears 34, 35, and the plates 36a, 36b are connected and supported by a plurality of support shafts 38 supporting the planetary bodies 37, thereby forming the carrier 36. In the above-described carrier 36 in which the first and second planetary gears 40 and 41 formed on each planetary body 37 are respectively engaged with the first and second sun gears 34 and 35 to rotatably support the carrier 36. Since the housing 36 is not supported with high rigidity by bearings in the housing, it is effective to rotationally drive the carrier 36 so that no radial force acts on the housing 36 in order to obtain smooth engagement, and furthermore, the degree of freedom in assembling is increased. Therefore, the backlash can be reduced by the engagement of the planetary gear and the sun gear, and the assembling can be facilitated.
[0031]
In the first embodiment described above, the plate 36a and the rotating body 33 are engaged by spline engagement with the spline shaft 45, so that the plate 36a and the rotating body 33 are firmly engaged. In addition, the rotating body 33 and the plate 36a (carrier 36) can be engaged so that only the rotational force can be reliably transmitted. Further, since the rotating body 33 which is rotated by the motor 32 and engages with the carrier is supported by the gear-side shaft 13 which is supported by the housing at two places, the rigidity can be maintained and the apparatus can be downsized. . Further, since the handle shaft 11 is connected to the handle 5 via the servo mechanism 2, the existing servo mechanism and the steering gear are used, and only the planetary gear mechanism 6 is added between the two to enable the variable reduction ratio power steering. The device 1 can be obtained.
[0032]
In the above-described first embodiment, the plate 36a and the rotating body 33 are spline-engaged with the spline shaft 45 which is a separate member. However, the spline shaft is engaged with one of the plate 36a and the rotating body 33. May be integrally formed, and a spline hole may be formed in the other, and these may be spline-engaged.
[0033]
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 components are denoted by the same reference numerals and detailed description is omitted. Only the differences will be described. As shown in FIG. 3, the three bearing shafts 38 are formed with engaging pins 38 a that extend and pass through the plate 36 a, and the engaging pins 38 a are drilled on the side surfaces of the rotating body 42. The rotating body 33 and the plate 36a, that is, the carrier 36 are engaged so that only the rotational force can be transmitted. When the rotating body 33 is rotated by the motor 32, the engaging pins 38a of the three support shafts 38 are engaged with the engaging holes 33a and driven to rotate, so that the radial component of the rotating force for rotating the carrier 36 is canceled. You. According to this, the plate 36a of the carrier 36, which is a separate member, and the rotating body 33 can be easily engaged by the engagement pin 38a. Further, since the conventionally used member, that is, the bearing shaft 38 can be used as a driving member of the carrier 36, an increase in the number of parts is prevented, and an increase in cost is suppressed.
[0034]
In the above-described second embodiment, the engaging pin 38a provided with the support shaft 38 is engaged with the rotating body 33. In addition, the engaging pin 38a protrudes from the plate 36a of the carrier 36. The engagement pin provided as described above may be engaged with the rotating body 33. For example, an engagement pin provided on the side surface of the plate 36a may be engaged with the rotating body 33.
[0035]
In the above-described embodiment, the three planets 37 are supported on the plates 36a, 36b loosely fitted to the first and second sun gears 34, 35 by the support shaft 38 at equal angular intervals on the circumference, thereby supporting the carrier 36. 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, to support the carrier 36 so as to be rotatable around the central axis O. Alternatively, the carrier may be rotatably supported on the housing around the central axis O by a bearing.
[0036]
Further, in the above embodiment, the planetary gear mechanism 6 is disposed at the subsequent stage of the servo valve device 3 by using the handle shaft 11 as the output shaft of the servo valve device 3. The planetary gear mechanism 6 may be arranged at a stage prior to the servo valve device 3 by using the input shaft as described above.
[0037]
In the above embodiment, the handle shaft 11 is supported by one bearing 12, but may be supported by two bearings at two points.
[0038]
In the above embodiment, the power steering device operates the servo valve device by the rotation of the handle to supply and discharge pressure oil to and from the cylinder device to axially move the rack shaft. The motor may be driven to rotate, 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.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a variable speed reduction type power steering apparatus according to a first embodiment.
FIG. 2 is a sectional view taken along line 2-2 of FIG.
FIG. 3 is a longitudinal sectional view of a variable reduction ratio power steering apparatus according to a second embodiment.
[Explanation of symbols]
DESCRIPTION OF REFERENCE NUMERALS 1: Variable reduction ratio 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: steering Nominal wheels, 9: Upper housing, 10: Lower housing, 10a: Gear housing part, 11: Handle side shaft, 12, 14, 15, 42 ... Bearing, 13: Gear side shaft, 18: Rotary valve, 20: Sleeve, Reference numeral 22: hydraulic pump, 23: tank, 24: torsion bar, 25: pinion, 26: rack, 27: rack shaft, 30: cylinder device, 32: motor, 33: rotating body, 33a: engagement hole, 34, 35 ... first and second sun gears, 36 ... carriers, 36a, 36b ... plates, 37 ... planetary bodies, 38 ... support shafts, 38a ... engagement pins, 40,41 ... first and second sun gears The second planetary gear 43 ... worm wheel, 44 ... worm, 45 ... spline shaft.

Claims (8)

In a power steering device in which rotation of a steering wheel is reduced by a steering gear and a steering mechanism acting on the steering wheel is amplified by a servo mechanism and transmitted to a steered wheel, a steering shaft connected to the steering wheel and a steering gear are provided. The connected gear-side shaft is rotatably mounted on the housing on the central axis, and first and second sun gears having slightly different numbers of teeth are provided at opposed shaft ends of the two shafts. A carrier that supports the first and second planetary gears that mesh with and rotate integrally with the second sun gear is rotatably supported around the central axis, and a rotating body that is rotationally connected to a motor is aligned with the carrier around the central axis. Rotatively supported, the rotating body and the carrier are engaged so as to be able to transmit only a rotating force, and the motor is connected to the rotating body via the rotating body. Reduction ratio variable type power steering apparatus characterized by varying the reduction ratio and rotating the said carrier. In a power steering device in which rotation of a steering wheel is reduced by a steering gear and a steering mechanism acting on the steering wheel is amplified by a servo mechanism and transmitted to a steered wheel, a steering shaft connected to the steering wheel and a steering gear are provided. A first gear and a second sun gear having slightly different numbers of teeth are provided at opposed shaft ends of the two shafts, the first and second sun gears being rotatably supported on a center axis of the housing. A planetary body having first and second planetary gears, which are rotatably engaged with the first and second sun gears and integrally rotate, respectively, are formed on a coaxial line. The planetary body is rotatably supported on the first and second sun gears by rotatably supporting the planetary gear, and is rotatably connected to the motor. Are arranged side by side on one of the pair of plates and rotatably supported about the central axis, the rotating body and the one plate are engaged so as to transmit only rotational force, and the motor is used for the rotation. A variable reduction ratio power steering apparatus wherein the pair of plates are rotationally driven through a body to change a reduction ratio. 3. The variable reduction ratio power steering apparatus according to claim 2, wherein the one plate and the rotating body are engaged by spline engagement. 3. The variable speed reduction type power steering device according to claim 2, wherein the one plate is engaged with the rotating body by engaging an engaging pin projecting from the one plate with the rotating body. . 5. The variable speed reduction type power steering device according to claim 4, wherein the engagement pin is formed by extending a support shaft that rotatably supports the planetary body and protruding from the plate. The gear shaft according to any one of claims 1 to 5, wherein the gear-side shaft is supported by the bearing at at least two places separated in the central axis direction from the housing, and the handle-side shaft is supported by the bearing at one place in the housing. A variable speed reduction type power steering device, characterized in that: 7. The variable-speed-ratio power steering apparatus according to claim 6, wherein the rotating body is supported on the gear-side shaft. The power reduction steering device according to any one of claims 1 to 7, wherein the handle-side shaft is connected to the handle via the servo mechanism.

Images