JP2004256087A - Reduction ratio variable power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reduction ratio variable power steering device capable of smooth rotation transmission. <P>SOLUTION: The power steering reduces the rotation of a steering wheel by a steering gear and amplifies steering force applied to the steering wheel by a servo mechanism to transmit it to a steerable wheel. A steering wheel shaft connected to the steering wheel and gear shaft connected to the steering gear are axially supported by a housing on a center axis line to be rotatable. Opposing axial ends of the steering shaft and the gear shaft are fitted thorough a bearing supporting radial loads to be relatively rotatatable around the center axis line. First and second sun gears having the slightly different number of teeth are provided on the opposing axial ends of both shafts to support a carrier, which supports first and second planetary gears respectively engaging the first and second gears and rotating together, to be rotatable around the center axis line. The carrier is rotated and driven by a motor to vary the reduction ration of the power steering device. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  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.

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. 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.
JP-A-60-209362 (pages 2, 3; FIG. 1)

  In the variable reduction ratio power steering apparatus, the handle shaft and the gear shaft are respectively supported by bearings at one location in the housing, and the handle shaft is centered by a torsion bar pinned to a shaft hole of the gear shaft. It is difficult to ensure concentricity between the handle shaft and the gear shaft due to the misalignment of the torsion bar and the gear shaft, and at the tip of both shafts. The rigidity of mutual support is low, and the rotation centers of the first and second sun gears may be displaced, and smooth rotation transmission between the sun gear and the planetary gear may not be performed. 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, 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, and the worm gear is fitted to an output shaft of a motor. Since the worm is engaged, the degree of freedom in assembling is reduced, and assembling and adjusting work becomes difficult. Further, since the first and second sun gears are rotationally connected only via the first and second planetary gears, play occurs on the handle side shaft with respect to the gear side shaft due to the backlash of the gear, so that the neutral position of the handle when the handle is in the neutral position is obtained. There is a problem that rigidity is reduced and steering feeling is reduced.

  SUMMARY OF THE INVENTION The present invention has been made to solve such a conventional problem, and an object of the present invention is to provide a variable reduction ratio power steering device capable of smoothly transmitting rotation.

  In order to solve the above-mentioned problem, 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 to the steering wheel. In a power steering apparatus for transmitting, a handle-side shaft connected to the handle and a gear-side shaft connected to the steering gear are rotatably supported on a housing on a central axis, and the handle-side shaft and the gear-side Opposite shaft ends of the shafts are fitted rotatably about the central axis via a bearing that supports a radial load, and the first and second shafts have slightly different numbers of teeth at the opposite shaft ends. And a second sun gear, and a carrier that supports the first and second planetary gears that mesh with the first and second sun gears and rotate integrally therewith. Rotatably supported around an axis is to vary the speed reduction ratio of the carrier was rotated by a motor.

  A structural feature of the invention according to claim 2 is that, in claim 1, the opposed shaft ends of the handle-side shaft and the gear-side shaft are arranged around the center axis through a bearing that supports a radial load. In order to fit relatively rotatably, a small-diameter portion extending along the central axis protrudes from one of the opposite shaft ends of the handle-side shaft and the gear-side shaft, and is the other of the two shaft ends. When a bearing for supporting the small diameter portion is provided, and the small diameter portion is inserted into the bearing in a state where the second planetary gear supported by the carrier is meshed with a second sun gear provided on the gear shaft, When the tip of the small-diameter portion is inserted into the open end of the bearing, a front sun gear provided on the handle shaft and the first planetary gear supported by the carrier are located forward. Clearance of the central axis line direction is that is formed.

  A structural feature of the invention according to claim 3 is that, in claim 1 or 2, a rotating body that is rotationally connected to the motor is rotatably supported around the central axis along with the carrier, and The carrier is rotatably engaged with the carrier, and the carrier is rotationally driven by the motor via the rotator to change the reduction ratio.

  A feature of the invention according to claim 4 is that, in any one of claims 1 to 3, the gear-side shaft is supported on the housing by a bearing at at least two positions separated in the center axis direction, and the handle-side shaft is provided. At one place in the housing by means of a bearing.

  A structural feature of the invention according to claim 5 is that, in claim 4, the rotating body is supported on the gear-side shaft.

  A structural feature of the invention according to claim 6 is that, in any one of claims 1 to 5, the handle-side shaft is connected to the handle via the servo mechanism.

  A structural feature of the invention according to claim 7 is that in the power steering device, 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. A handle-side shaft connected to the steering wheel and a gear-side shaft connected to the steering gear are rotatably supported on the housing on a central axis, and a relative rotation between the handle-side shaft and the gear-side shaft is prevented. First and second sun gears having slightly different numbers of teeth are provided at opposed shaft ends of the shafts with frictional members interposed therebetween, and mesh with the first and second sun gears to rotate integrally. A carrier that supports the first and second planetary gears is rotatably supported around the central axis, and the carrier is rotated by a motor to change the reduction ratio. Is Rukoto.

  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 that rotate integrally with the first and second sun gears is rotatably supported around a 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 opposite shaft ends of the handle-side shaft and the gear-side shaft are supported with high rigidity by bearings that support a load in the radial direction, and rotate relative to each other about the central axis, so that the rotation centers of the first and second sun gears are shifted. Highly consistent, smooth rotation transmission between the sun gear and the planetary gear can be performed.

  In the invention according to claim 2 configured as described above, 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, concentricity between the handle shaft and the gear shaft is established. The first sun gear and the first planetary gear can be meshed with each other in a state where is established, and the assembling work can be facilitated.

  In the invention according to claim 3 configured as described above, the rotating body rotatably connected to the motor is rotatably supported around the same central axis alongside the carrier, so that the rotating body and the carrier can be transmitted in rotation. Since the carrier is engaged, the carrier can be prevented from being displaced by receiving the force in the radial direction by the rotational driving force, and the rotation can be smoothly transmitted between the planetary gear and the sun gear.

  In the invention according to claim 4 configured as described above, the gear-side shaft is supported by the housing at at least two places separated in the center axis direction by the bearing. The handle-side shaft is supported by a bearing at one location in the housing, and the shaft end is supported by the bearing on the gear-side shaft. 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.

  In the invention according to claim 5 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 at two locations on the housing, high rigidity is maintained. As a result, the size of the device can be reduced.

  In the invention according to claim 6 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.

  In the invention according to claim 7 configured as described above, the relative rotation between the handle-side shaft and the gear-side shaft which are rotationally connected by the engagement of the first and second sun gears and the first and second planetary gears is provided. Since the frictional body serving as the resistance is interposed, the play due to the backlash of the gear is reduced by the frictional body, the steering feeling is improved, and the rigidity when the steering wheel is neutral is also increased.

(Example 1)
Hereinafter, a variable reduction ratio 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.

  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 around the central axis O by a bearing 12 at one position in the upper housing 9. The rack and pinion mechanism 7 is housed in the lower housing 10, and the gear-side shaft 13, which is the pinion shaft of the rack and pinion mechanism 7, is rotatable around the central axis O by bearings 14 and 15 at two places separated in the direction of the central axis O. It is bearing. The handle 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 protrudes from the shaft end. A bearing hole 13a is formed at the shaft end of the gear-side shaft 13 opposite the handle-side shaft 11, and a small-diameter portion 11a is rotatably supported by the needle bearing 16 in the bearing hole 13a. In this way, the opposite shaft ends of the handle shaft 11 and the gear shaft 13 have high concentricity around the central axis O through the bearings that support the radial load, and are relatively rotatable with high rigidity. 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 shaft 11 is rotatably fitted around the central axis O into a distribution hole 19 formed in the upper housing 9, 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, etc., 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 connected to the hydraulic pump 22 and The ports are connected to the P and T ports respectively connected to the tank 23. 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.

  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.

  The planetary gear mechanism 6 and a rotating body 33 driven to rotate by a motor 32 are housed side by side in the gear housing 9 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. 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 of the plate 36a and 36b, Both ends are supported rotatably via a bush 39 by a bearing shaft 38 having both ends supported by 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. At the bottom of the gear housing portion 9a, a rotating body 33 is supported by the bearing 42 on the gear shaft 13 so as to be rotatable around the central axis O alongside 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 on an output shaft of the motor 32 fixed to the lower housing 10. Each bearing shaft 38 penetrates the plate 36a and is fitted in 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 be able to transmit rotation.

  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 example, r = 20 · 20/21 · 21 = 0.91, and when the carrier 36 is rotated in the same direction as the handle 5, the number of teeth is determined according to the rotation speed n3. 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.

  At this time, the opposing shaft ends of the handle shaft 11 and the gear shaft 13 have high concentricity around the central axis O through a needle bearing 16 that supports a radial load, and are relatively rotatable with high rigidity. , The rotation centers of the first and second sun gears 34 and 35 match with high precision, and smooth rotation transmission between the sun gear and the planetary gears can be performed. When the rotating body 33 is rotated by the motor 32, the bearing shaft 38 engaged with the rotating body 33 is driven to rotate, and the radial component of the rotating force for rotating the carrier 36 is canceled. Thus, the first and second planetary gears 40, 41 can smoothly mesh with the first and second sun gears 34, 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 the plurality of planets 37 are supported on the plates 36a and 36b by the support shaft 38 at equal angular intervals on the circumference to support the carrier 36. In the above-described carrier 36 configured and configured to mesh 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, to rotatably support the carrier 36. Since the carrier 36 is not supported with high rigidity by a bearing on the housing, it is effective to rotationally drive the carrier 36 so that no radial force acts on the carrier 36 in order to obtain smooth engagement.

(Example 2)
Next, a second embodiment will be described. Since the configuration of the variable speed reduction type power steering device 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 thereof will be omitted. Only the differences will be described. As shown in FIG. 3, in the second embodiment, a sliding hole 13b is formed in the shaft end of the gear-side shaft 13 continuously with the bearing hole 13a, 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 11a of the handle shaft 11 by the spring force of the compression spring 46. In this way, the friction body 45 that acts as a resistance against relative rotation is interposed between the handle shaft 11 and the gear shaft 13. The friction member may be interposed between the opposing side surfaces of the first and second sun gears 34, 35. Further, even when the opposed shaft ends of the handle-side shaft 11 and the gear-side shaft 13 are not fitted through a bearing, resistance to relative rotation between the handle-side shaft and the gear-side shaft is reduced. May be interposed.

  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 the engagement 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, the friction body 45 becomes resistant to the relative rotation between the handle shaft 11 and the gear shaft 13, thereby reducing the play due to the backlash of the gear, Improves steering feeling and increases rigidity when the steering wheel is neutral.

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

  Further, in the above embodiment, the planetary gear mechanism 5 is disposed at the subsequent stage of the servo valve device 3 by setting the output shaft of the servo valve device 3 to the handle shaft 11, but the gear shaft 13 is connected to the servo valve device 3. The planetary gear mechanism 5 may be arranged in front of the servo valve device 3 by using the input shaft 3.

  In the above embodiment, the power steering device operates the servo valve device by the rotation of the handle to supply and discharge the pressure oil to and from the cylinder device to axially move the rack shaft. May be driven to rotate the rack shaft 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 speed reduction type power steering apparatus of the third embodiment is the same as that of the second embodiment, except that the dimensional relationship of the components is different. That is, as shown in FIG. 4, the length of the small diameter portion 11a protruding from the shaft end of the handle shaft 11 is set to L1, and the second sun gear 35 and the planetary gears 40, 41 and the like are assembled to the lower housing 10. When the distance from the shaft end of the gear-side shaft 13 to the end surface of the first planetary gear 40 on the opening side of the lower housing 10 is L2, the length L1 is longer than the length L2. With such a dimensional relationship, the first planetary gear 40 supported by the carrier 36 and the first sun gear 34 provided on the handle shaft 11 when the tip of the small diameter portion 11a is inserted into the open end of the bearing hole 13a. And a gap in the central axis direction is formed between them. The procedure of the assembling work will be described below. Assembling is performed separately in 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-connected. The servo valve device 3 is assembled. Then, the assembled servo valve device 3 is accommodated in the upper housing 9 by being supported by the 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 bearing shaft 38 is fitted in an engaging hole 33a of the rotating body 33 with the planetary body 37 and the plates 36a, 36b. The planetary gear mechanism 6 configured as described above is fitted. Then, 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 shaft 13, the worm 44 is meshed with the worm wheel 43 of the rotating body 33, and the motor 32 is moved to the lower housing 10. Fixed to.

   As described above, the servo valve device 3 is stored in the upper housing 9, and the planetary gear mechanism 6 and the rack and pinion mechanism 7 are stored in the lower housing 10. Thereafter, the compression spring 46 and the friction sliding body 45 are housed in the sliding hole 13b of the gear-side shaft 13 assembled in the lower housing 10, and the needle bearing 16 is housed in the bearing hole 13a. Then, the small diameter portion 11a of the handle 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 shaft 11 are meshed. At this time, as shown in FIG. 4, the small-diameter portion 11a is supported by the needle bearing 16 before the first planetary gear 40 and the first sun gear 34 mesh. This allows the first planetary gear 40 and the first sun gear 34 to mesh with each other after the handle shaft 11 and the gear shaft 13 are aligned on the rotation axis O, so that both can be meshed and inserted. It will be easier. 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 mesh with each other, the small-diameter portion 11a is inserted up to the sliding hole 13b and comes into contact with the friction sliding member 45, compressing the compression spring 46 to compress the small-diameter portion 11a and the friction sliding member 45. Will adhere. Thereafter, the upper housing 9 and the lower housing 10 are fixed by the bolts 47, and the assembling operation is completed.

   In the embodiment shown in FIG. 4, the sliding hole 13b is formed in the gear shaft 13 following the bearing hole 13a, and the friction sliding body 45 is used in combination. It is not always necessary to use the moving body 13b together. Alternatively, the small-diameter portion 11a may be formed in the gear-side shaft 13, the bearing hole 13a may be formed in the handle-side shaft 11, and the gear-side shaft 13 may be supported by the handle-side shaft 11.

FIG. 2 is a longitudinal sectional view of the variable speed reduction type power steering device according to the first embodiment. Sectional drawing cut | disconnected along the II-II line of FIG. FIG. 6 is a longitudinal sectional view of the second embodiment. FIG. 11 is a longitudinal sectional view illustrating an assembled state of an upper housing and a lower housing according to a third embodiment.

Explanation of reference numerals

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, 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 gear, 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 (7)

In a power steering device in which the rotation of a steering wheel is reduced by a steering gear and the steering force acting on the steering wheel is amplified by a servo mechanism and transmitted to steered wheels, a steering shaft connected to the steering wheel and a steering gear are provided. The coupled gear-side shaft is rotatably mounted on the housing on the center axis so as to be rotatable, and the handle-side shaft and the opposite shaft end of the gear-side shaft are interposed with a bearing for supporting a radial load. First and second sun gears having slightly different numbers of teeth are provided at opposed shaft ends of both shafts, 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 rotationally driven by a motor. Reduction ratio, characterized in that changing the reduction ratio variable type power steering device. 2. The handle side according to claim 1, wherein opposite shaft ends of the handle side shaft and the gear side shaft are fitted so as to be relatively rotatable around the central axis through a bearing that supports a radial load. 3. A small-diameter portion extending along the central axis is protruded at one of two opposed shaft ends of the shaft and the gear-side shaft, and a bearing for supporting the small-diameter portion is provided at the other of the two shaft ends, and the gear is provided. When the small diameter portion is inserted into the bearing in a state where the second planetary gear supported by the carrier is meshed with the second sun gear provided on the side shaft, the tip of the small diameter portion is inserted into the open end of the bearing. A gap in the center axis direction is formed between a first sun gear provided on the handle shaft and the first planetary gear supported by the carrier when the first sun gear is provided. Reduction ratio wherein the variable type power steering device. The rotary body according to claim 1 or 2, wherein the rotary body rotatably connected to the motor is rotatably supported around the central axis alongside the carrier, and the rotary body and the carrier are engaged so as to transmit rotation. A variable reduction ratio type power steering device wherein the carrier is rotated by a motor via the rotating body to change the reduction ratio. The gear shaft according to any one of claims 1 to 3, wherein the gear-side shaft is supported by the bearing at at least two places separated in the center axis direction by the bearing, and the handle-side shaft is supported by the bearing at one place on the housing. Characteristic variable speed ratio type power steering device. 5. The variable speed reduction type power steering device according to claim 4, wherein the rotating body is supported on the gear-side shaft. 6. The variable speed reduction type power steering device according to claim 1, wherein the handle-side shaft is connected to the handle via the servo mechanism. 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 coupled gear-side shaft is rotatably mounted on the housing on the center axis so as to be rotatable, and a friction member that resists relative rotation is interposed between the handle-side shaft and the gear-side shaft. First and second sun gears having slightly different numbers of teeth are provided at opposite shaft ends, and the carrier that supports the first and second planetary gears that mesh with the first and second sun gears and rotate integrally therewith is provided at the center. A variable reduction ratio type power, which is rotatably supported around an axis and changes the reduction ratio by rotating the carrier by a motor. Take apparatus.

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