JP2004224085A - Reduction gear ratio variable type power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a miniaturized, lightweight and rigid reduction gear ratio variable type power steering device wherein the number of parts is reduced. <P>SOLUTION: In the power steering device wherein the rotation of a steering wheel is reduced by a steering gear and a steering input acting on the steering wheel is amplified by a servo mechanism in order to transmit it to a steered wheel, a steering wheel side shaft connected to the steering wheel and a gear side shaft connected to the steering gear are rotatably supported on a housing along a central axis. First and second sun gears having slight different numbers of teeth from each other are integrally provided at shaft ends wherein both the shafts are confronted, and a planetary body wherein first and second planetary gears meshed with the first and the second sun gears, respectively, so as to integrally rotate are formed along the same axis is held on a carrier rotatably supported on the housing around the central axis. The carrier is rotated and driven by a motor fixed on the housing, and a rotation ratio of the steering wheel side shaft and the gear side shaft is varied. <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 wheel turning angle is small, the steering gear reduction ratio is reduced to improve the steering wheel sharpness, and when the steering angle is large, the steering gear reduction ratio is increased to make operation easier, or the steering wheel turning angle and the reduction ratio are reduced. The relationship may be reversed from the one described above. In addition, it is desired to reduce the turning angle of the steering wheel by making the reduction ratio considerably small in a garage or the like. To cope with this, in a power steering device in which the rotation of the steering wheel is reduced by the steering gear and the steering input acting on the steering wheel is amplified by the 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-ratio power steering apparatus in which the rotation ratio of a servo valve device to an input shaft is variable. In this conventional device, a first sun gear is spline-coupled to a steering shaft, and a second sun gear having a different number of teeth from the first sun gear is spline-coupled to an input shaft. First and second planetary gears, which are respectively meshed with the first and second sun gears and are integrally formed, are rotatably supported by the support shaft, and both ends of the support shaft are supported by the carrier. The carrier is rotatably supported on a steering shaft and an input shaft, and a worm that meshes with a worm gear engraved on the outer periphery is rotated by a motor to change the rotation ratio between the steering shaft and the input shaft.
[0003]
[Patent Document 1]
JP-A-60-209362 (pages 2, 3; FIG. 1)
[0004]
[Problems to be solved by the invention]
In the variable speed reduction type power steering device, the first sun gear is spline-coupled to the steering shaft connected to the steering wheel, the second sun gear is spline-coupled to the input shaft of the servo valve device, and both ends of the bearing shaft supporting the planetary gear are provided. Since the carrier is supported by the carrier and the carrier is rotated by the motor by the worm wheel, there are problems that the number of parts increases and the size of the apparatus increases. Further, since the carrier is supported on the steering shaft and the input shaft, there is a problem that sufficient rigidity cannot be obtained.
[0005]
SUMMARY OF THE INVENTION The present invention has been made to solve such a conventional problem, and it is an object of the present invention to provide a high-rigidity variable-ratio-ratio power steering apparatus in which the number of parts is reduced and the apparatus is reduced in size and weight.
[0006]
[Means for Solving the Problems]
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 input acting on the steering wheel is amplified by the servo mechanism to the steering wheel. In a power steering apparatus for transmitting, a handle shaft connected to the handle and a gear shaft connected to the steering gear are rotatably supported on a housing on a central axis, and opposed shaft ends of both shafts. First and second sun gears having slightly different numbers of teeth are integrally provided on the portion, and a planetary body in which first and second planetary gears meshing with the first and second sun gears and integrally rotating are formed on a coaxial line. The carrier is supported on the housing so as to be rotatable around the center axis, and the carrier is rotationally driven by a motor fixed to the housing. Reduction ratio, characterized in that changing the rotational ratio between the gear-side shaft and the handle-side shaft Te variable power steering system.
[0007]
A structural feature of the invention according to claim 2 is that, in claim 1, the handle-side shaft is a steering shaft connected to the handle, and the gear-side shaft is an input shaft of the servo mechanism. is there.
[0008]
A structural feature of the invention according to claim 3 is that, in claim 1 or 2, the carrier is disposed between opposing side surfaces of the first and second sun gears, and the planetary body is rotated by the carrier at a central portion. Preferably, the first and second planetary gears protrude from both side surfaces of the carrier, respectively, and mesh with the first and second sun gears.
[0009]
A structural feature of the invention according to claim 4 is that, in any one of claims 1 to 3, the motor is disposed parallel to the center axis, and a pinion rotationally connected to an output shaft of the motor is provided on the carrier. That is, it meshed with the large gear provided on the outer periphery.
[0010]
A structural feature of the invention according to claim 5 is that, in any one of claims 1 to 4, the first and second planetary gears have the same specifications, and the first and second sun gears shift at least one of them. That is, the number of teeth was different.
[0011]
The structural feature of the invention according to claim 6 is that, in claim 5, the planetary gears having the same specifications are continuously formed over the entire width of the planetary body, and a collar is fitted to a central portion of the planetary body. The planet is supported by the carrier with the collar.
[0012]
A structural feature of the invention according to claim 7 is that, in any one of claims 1 to 6, the planetary body includes first and second planetary gears that mesh with the first and second sun gears and rotate integrally. A planetary main body integrally formed on a coaxial line, and first and second gears meshed with the first and second sun gears and urged by a spring member to rotate relative to the planetary main body on the coaxial line. And a second backlash removing gear.
[0013]
[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. , The first and second planetary gears meshing with the first and second sun gears are rotatably supported on the housing for supporting the planetary body formed on the housing, so that the rotation of the handle shaft depends on the rotation of the carrier. The speed is changed by the planetary gear mechanism and transmitted to the gear shaft, so that the reduction ratio as the power steering device is changed. In such a variable speed reduction type power steering device, the number of components can be reduced to reduce the size of the device, and the rigidity of the device can be increased by supporting the carrier on the housing.
[0014]
In the invention according to claim 2 configured as described above, the handle-side shaft is the steering shaft connected to the handle, and the gear-side shaft is the input shaft of the servo mechanism. It is small and the device can be miniaturized.
[0015]
In the invention according to claim 3 configured as described above, the carrier is arranged between the opposed side surfaces of the first and second sun gears. The planet is rotatably supported by the carrier at a central portion, and first and second planetary gears projecting from both side surfaces of the carrier are meshed with the first and second sun gears. Thus, the length of the device in the axial direction can be reduced.
[0016]
In the invention according to claim 4 configured as described above, the motor is arranged in parallel with the center axis of the handle-side shaft or the like, and the pinion rotatably connected to the output shaft of the motor is provided on the large gear provided on the outer periphery of the carrier. Since they are engaged, the configuration can be simplified and the size can be reduced.
[0017]
In the invention according to claim 5 configured as described above, the first and second planetary gears have the same specifications, and at least one of the first and second sun gears is transposed to have a different number of teeth from the other. A planetary gear can be easily manufactured at low cost.
[0018]
In the invention according to claim 6 configured as described above, the planetary gears having the same specifications are continuously formed over the entire width of the planetary body, and a collar is fitted to a central portion of the planetary body, and the planetary gear is fitted with the collar. Since the carrier is supported by the carrier, the planetary gear and its bearing can be easily manufactured at low cost.
[0019]
In the invention according to claim 7 configured as described above, the first and second planetary gears formed on the coaxial line in the planet main body mesh with the first and second sun gears respectively, and are coaxial with the planet main body. The first and second backlash removing gears biased by the spring member to relatively rotate on the line mesh with the first and second sun gears, respectively, so that the first and second sun gears, the first and second planetary gears, Can be engaged with each other by removing the backlash with a simple configuration.
[0020]
Embodiment
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. 1 and 2, a variable reduction ratio type power steering device 1 mainly includes a handle shaft 3 to which the rotation of a handle 2 is transmitted, and a planetary gear mechanism that changes the speed of rotation of the handle shaft 3 and transmits the rotation to a gear shaft 4. 5, a servo valve device 7 of a hydraulic servo mechanism 6 having the gear shaft 4 as an input shaft, a rack and pinion mechanism 8 as a steering gear connected to the servo valve device 7, and hydraulic pressure supplied according to the functions of the servo valve device 7. It comprises a cylinder device 11 which is driven out and is driven by a rack shaft 10 connected to the steering wheel 9.
[0021]
The upper housing 12, the middle housing 13, and the lower housing 21 are connected to each other to form a housing. The handle-side shaft 3 is rotatably supported on the center axis O by the upper housing 12, and the upper housing 12, the middle housing 13, The planetary gear mechanism 5 is housed in a gear housing 14 formed at a joint portion of the gears, and the gear-side shaft 4 is rotatably supported on a middle housing 13 on a central axis O. A rotary valve 15 is formed on the gear-side shaft 4 that is the input shaft of the servo mechanism. A sleeve 17 rotatably connected to a pinion shaft 19 of the rack and pinion mechanism 8 is rotatably fitted in a storage hole 16 formed in the middle housing 13, and a rotary valve 15 is fitted in a valve hole 18 formed in the sleeve 17. It is fitted rotatably. The servo valve device 7 is constituted by the rotary valve 15, the sleeve 17, etc., and the A and B ports respectively connected to the left and right chambers of the cylinder device 11 according to the relative rotation of the rotary valve 15 and the sleeve 17 are connected to the hydraulic pump 43 and The ports are connected to the P and T ports respectively connected to the tank 44. The gear shaft 4 and the pinion shaft 19 are respectively connected to both ends of the torsion bar 20. When the steering shaft is not actuated on the steering wheel 2 and the gear shaft 4 is in a free state, the P and T ports are communicated and A and T are connected. The rotary valve 15 is rotationally positioned relative to the sleeve 17 at a neutral position where no oil pressure is generated at the B port.
[0022]
The pinion shaft 19 is rotatably mounted on a lower housing 21 fixed to the middle housing 13 so as to be rotatable on a center axis O, and includes a rack shaft 10 provided with a rack 23 meshed with a pinion 22 formed on the pinion shaft 19. It is slidably mounted on the lower housing 21. As shown in FIG. 2, a cylinder 24 is fixed to the lower housing 21, and a piston 25 fixed to the rack shaft 10 is fitted to the cylinder 24 to constitute the cylinder device 11. A knuckle arm is connected to both protruding ends of the rack shaft 10 via a tie rod by a ball joint, and the steering wheel 26 is deflected by the axial movement of the rack shaft 10.
[0023]
First and second sun gears 27 and 28 in which the number of teeth of the planetary gear mechanism 5 is slightly different are integrally provided at the opposed shaft ends of the handle shaft 3 and the gear shaft 4, respectively. A carrier 29 is disposed between opposing side surfaces of the first and second sun gears 27 and 28. The carrier 29 is rotated around a central axis O by a bearing 30 in the gear housing 14 by a bearing portion 29a projecting cylindrically from both side surfaces. Supported as possible. One or more (for example, three on the circumference) planetary bodies 31 are rotatably supported on the carrier 29 by a bearing bush 34 at a central portion thereof. First and second planetary gears 32 and 33 which mesh with first and second sun gears 27 and 28 and rotate integrally with the first and second sun gears 27 and 28, respectively, are integrally formed on both ends of each planet 31 protruding from both side surfaces of the carrier 29 on a coaxial line. Is formed. The axial movement of each planetary body 31 is restricted by the outer surfaces of the first and second planetary gears 32 and 33 contacting the inner wall surface of the gear housing 14. The number of teeth of the first and second sun gears 27 and 28 and the number of teeth of the first and second planetary gears 32 and 33 were set to 20, 21, 21 and 20, for example. A large gear 35 is formed in a large diameter portion between the bearings 30 on both sides of the carrier 29, and a small gear 36 meshing with the large gear 35 is rotatably supported by the gear housing 14 in parallel with the central axis O. A motor 37 is fixed to the gear housing 14 in parallel with the central axis O, and an output shaft 38 is rotatably connected to the small gear 36.
[0024]
Next, the operation of the first embodiment will be described. When the handle 2 is turned and the handle shaft 3 is rotated n1 times, the gear shaft 4 is shifted by the planetary gear mechanism 5 and rotated n2 times. At this time, the rotation ratio r = n2 / n1 between the gear-side shaft 4 and the handle-side shaft 3 is n2 / n1 = r + n3 / n1 (1-r), where n3 is the rotation of the carrier 29. Here, assuming that the number of teeth of the first and second sun gears 27 and 28 and the first and second planetary gears 32 and 33 is z1, z2, z3 and z4, r is the rotation ratio r when the carrier 29 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. When the carrier 29 is rotated in the same direction as the handle 2, 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 29 is rotated in the opposite direction to the steering wheel 2, the reduction ratio of the power steering device as a whole increases.
[0025]
When the steering wheel 2 is turned, the electronic control unit (not shown) calculates the rotation direction and the number of rotations of the motor 37 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. The motor 37 is driven to rotate. When the gear shaft 4 is rotated by the planetary gear mechanism 5 and rotated at the rotation speed n2, the rotary valve 15 and the sleeve 7 are rotated relative to each other by twisting the torsion bar 20, and the pressure oil supplied from the pump 43 is supplied to the handlebar. In accordance with the rotation direction 2, the air is supplied from the A or B port to the left chamber 24a or the right chamber 24b of the cylinder device 11, the rack shaft 10 is axially moved, and the steered wheels 26 are deflected.
[0026]
Next, a second embodiment will be described. 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. Therefore, the same components are denoted by the same reference numerals, and detailed description is omitted. Only points will be described. As shown in FIG. 3, the planetary body 40 of the planetary gear mechanism 5 has a planetary gear 41 of the same specifications continuously formed over the entire width, and displaces one or both of the first and second sun gears 27 and 28. The center distance with the planetary gear 41 is adjusted. A collar 42 is fitted to the center of the planetary body 40, and the planetary body 40 is rotatably supported by the carrier 29 with the collar 42 fitted into the bearing bush 34. Portions of the planetary gear 41 projecting from both side surfaces of the carrier 29 function as first and second planetary gears 32, 33, and mesh with the first and second sun gears 27, 28, respectively.
[0027]
Next, a third embodiment will be described. Since the configuration of the variable speed reduction type power steering apparatus of the third 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 points will be described. As shown in FIG. 4, the rotation of the steering wheel 2 is transmitted to the input shaft 45 of the servo valve device 7 of the hydraulic servo mechanism 6 and the output of the servo valve device 7 is changed. The rotation of the shaft 46 is shifted by the planetary gear mechanism 5 and transmitted to the pinion shaft 47 of the rack and pinion mechanism 8. The output shaft 46 and the pinion shaft 47 function as the handle shaft 3 and the gear shaft 4, respectively.
[0028]
The upper housing 48 and the lower housing 49 are connected by bolts to form a housing. The upper housing 48 houses the servo valve device 7, and the lower housing 49 houses the rack and pinion mechanism 8. The planetary gear mechanism 5 is housed in the gear housing 14 formed at the joint between the upper housing 48 and the lower housing 49. First and second sun gears 27 and 28 in which the number of teeth of the planetary gear mechanism 5 is slightly different from each other are integrally provided at opposed shaft ends of the output shaft 46 and the pinion shaft 47, respectively. A carrier 50 is supported by the gear housing 14 such that the small diameter portions at both ends are rotatable around a central axis O by bearings 51. In the carrier 50, a large gear 35 is formed in a large diameter portion between the bearings 51, and a single or plural (for example, three on the circumference) which accommodates and supports the first and second planetary gears 32, 33 in a middle diameter portion. The first and second sun gears 27 and 28 are arranged in a through hole 50b formed in the axis.
[0029]
A support shaft 53 that rotatably supports the planet main body 54 via a bearing bush 55 is fitted to the hole wall of each holding hole 50a at both ends in parallel with the center axis O. First and second planetary gears 32, 33 which mesh with the first and second sun gears 27, 28 and rotate integrally therewith are formed on a coaxial line. First and second backlash removing gears 56 and 57 that mesh with the first and second sun gears 27 and 28, respectively, are rotatably supported on both sides of the planet main body 54 via bearing bushes on each bearing shaft 53. . Torsion springs 58a and 58b for removing backlash are inserted into the bearing shaft 53 by helical portions and housed in concave portions 54a and 54b formed on both side surfaces of the planet main body 54. One end of each of the torsion springs 58a, 58b is engaged with a hole formed through the planetary body 54 in the axial direction, and the other end is formed in the first and second backlash removing gears 56, 57. The first and second backlash removing gears 56 and 57 are urged to rotate relative to the planet main body 54 on the support shaft 53, and the first and second sun gears 27 and 28 are engaged with the retaining holes. The backlash in each meshing between the first and second planetary gears 32 and 33 is eliminated.
[0030]
In the third embodiment, when the handle 2 is turned, the rotary valve 15 and the sleeve 7 are relatively rotated by twisting the torsion bar 20, and the pressure oil supplied from the pump 43 is changed according to the rotation direction of the handle 2. The air is supplied from the A or B port to the left chamber 24a or the right chamber 24b of the cylinder device 11, and the rack shaft 10 is pivoted to deflect the steered wheels 26. At this time, the rotation speed n2 of the output shaft 46 is changed to the rotation speed n2 by the planetary gear mechanism 5 in accordance with the rotation speed of the motor 37 and the rotation speed n3 of the carrier 50 as described above, and transmitted to the pinion shaft 47. Is done.
[0031]
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 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 vertical sectional view of a variable reduction ratio power steering apparatus according to a first embodiment.
FIG. 2 is a sectional view taken along the line II-II of FIG.
FIG. 3 is a longitudinal sectional view of a second embodiment.
FIG. 4 is a longitudinal sectional view of a third embodiment.
5 is a sectional view taken along line VV of FIG. 4;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Variable-speed-ratio variable power steering device, 2 ... Handle, 3 ... Handle side shaft, 4 ... Gear side shaft, 5 ... Planetary gear mechanism, 6 ... Hydraulic servo mechanism, 7 ... Servo valve device, 8 ... Rack and pinion mechanism, 9: Steering wheel, 10: Rack shaft, 11: Cylinder device, 12, 48: Upper housing, 13: Middle housing, 14: Gear housing, 17: Sleeve, 18: Rotary valve, 19: Pinion shaft, 20: Torsion Bar, 21, 49 Lower housing, 22 Pinion, 23 Rack, 27, 28 First and second sun gear, 29, 50 Carrier, 31, 40 Planet, 32, 33 First and second Planetary gear, 35: Large gear, 36: Small gear, 37: Motor, 41: Planetary gear, 42: Collar, 43: Hydraulic pump, 45: Input shaft, 46 Output shaft (handle side shaft) 47 ... pinion shaft (gear-side shaft), 53 ... support shaft, 54 ... planet body portion, 56, 57 ... first and second backlash removing gear, 58a, 58b ... torsion spring.

Claims (7)

In a power steering device in which the rotation of a steering wheel is reduced by a steering gear, and a steering input 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 integrally provided at opposed shaft ends of the shafts with a gear side shaft connected to the housing on a central axis of the housing. First and second planetary gears that mesh with and rotate integrally with the second sun gear respectively support a planetary body formed on a coaxial line on a carrier rotatably supported on the housing around the central axis. Rotationally driven by a motor fixed to the housing to change the rotation ratio between the handle shaft and the gear shaft Reduction ratio, wherein the door variable power steering system. 2. The variable speed reduction type power steering apparatus according to claim 1, wherein the handle-side shaft is a steering shaft connected to the handle, and the gear-side shaft is an input shaft of the servo mechanism. The carrier according to claim 1 or 2, wherein the carrier is disposed between opposing side surfaces of the first and second sun gears, the planetary body is rotatably supported on the carrier at a central portion, and the first and second planetary gears are arranged. A variable reduction ratio type power steering device characterized in that the carrier projects from both side surfaces of the carrier and meshes with the first and second sun gears. The motor according to any one of claims 1 to 3, wherein the motor is disposed parallel to the center axis, and a pinion rotatably connected to an output shaft of the motor meshes with a large gear provided on an outer periphery of the carrier. Variable speed ratio type power steering device. 5. The reduction ratio according to claim 1, wherein the first and second planetary gears have the same specifications, and at least one of the first and second sun gears is displaced to have a different number of teeth. Variable power steering. 6. The planetary gear according to claim 5, wherein the planetary gears having the same specifications are continuously formed over the entire width of the planetary body, and a collar is fitted to a center portion of the planetary body, and the collar supports the planetary body on the carrier. A variable speed reduction type power steering device, characterized in that: The planetary body according to any one of claims 1 to 6, wherein the first and second planetary gears that respectively mesh with the first and second sun gears and integrally rotate are integrally formed on a coaxial line, A first and a second backlash removing gear meshed with the first and second sun gears and urged by a spring member so as to rotate relative to the planet main body on the coaxial line. Variable speed ratio type power steering device.

Images