JP2005247088A - Reduction gear ratio variable type power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve durability of a reduction gear ratio variable type power steering device by circulating low pressure operating oil delivered from a servo valve device into a planetary gear chamber, dipping a planetary gear mechanism in oil and improving the lubricating characteristic. <P>SOLUTION: Steering force applied to a steering wheel is amplified by the hydraulic servo valve device, and is transmitted to a steered wheel. Rotation speed of a shaft on a steering wheel side is changed by the planetary gear mechanism in correspondence with rotation of a carrier rotated and controlled by a motor, and is transmitted to a steering gear, and a reduction gear ratio as the power steering device is varied. A valve housing hole wherein the servo valve device is housed and the planetary gear chamber wherein the planetary gear mechanism is housed are formed adjacent to a housing, a return port for delivering the operating fluid from the servo valve device is opened to the planetary gear chamber, and the planetary gear mechanism is lubricated by the operating fluid circulated to the planetary gear chamber from the servo valve device. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a power steering apparatus that amplifies a steering input acting on a handle by a hydraulic servo valve device and transmits the amplified steering input to a steered wheel.

  When the turning angle of the steering wheel is small, the reduction ratio of the steering gear may be reduced to improve the cutting of the steering wheel. When the turning angle is increased, the reduction ratio may be increased to facilitate operation. Further, when the steering angle of the steering wheel is small and the steering angle of the steering wheel is small, the steering gear reduction ratio is increased to improve the neutral stability of the steering wheel. Furthermore, it is desirable to reduce the steering angle by reducing the reduction ratio considerably in garage storage.

  In order to cope with these, conventionally, in a power steering device that amplifies a steering input acting on a steering wheel by a hydraulic servo valve device and transmits it to a steered wheel, a steering shaft connected to the steering wheel and an input of the servo valve device Japanese Patent Application Laid-Open No. 60-209362 discloses a variable speed reduction type power steering apparatus in which a rotation ratio with a shaft is variable.

  In this conventional device, the handle side shaft and the gear side shaft, which is the input shaft of the servo valve device, are supported by bearings on the housing, and the handle side shaft is centered by a torsion bar pinned in the shaft hole of the gear side shaft. This is supported coaxially. A first sun gear is spline coupled to the handle side shaft, and a second sun gear having a different number of teeth from the first sun gear is spline coupled to the gear side shaft.

  And the planet body which formed the 1st and 2nd planetary gear which meshes | engages with a 1st and 2nd sun gear, respectively is rotatably supported by the support shaft, and the both ends of this support shaft are supported by the carrier. The carrier is rotatably supported by the handle side shaft and the gear side shaft, and the worm meshed with the worm gear engraved on the outer periphery of the carrier is rotated by the motor so that the rotation ratio between the handle side shaft and the gear side shaft is a planet. It can be changed by a gear mechanism.

JP-A-60-209362 (pages 2, 3 and 1)

  In the above-described conventional variable reduction ratio type power steering device, a planetary gear is sealed in a liquid-tight manner by a seal member between a valve housing hole that houses a servo valve device and a planetary gear chamber that houses a planetary gear mechanism. The mechanism was lubricated with grease. However, lubrication with grease causes insufficient lubrication of the gear tooth surfaces and the gear bearing portion, which may cause a problem in durability. In addition, the processing of the seal member and its fitting hole is expensive, and the longitudinal dimension of the device is increased by the amount of the seal member.

  The present invention has been made to solve the above-described conventional problems, and by circulating the low-pressure hydraulic oil used in the servo valve device to the planetary gear chamber, the planetary gear mechanism is immersed in oil and has lubricity. It is to improve the durability of the power steering apparatus with variable reduction ratio.

  In order to solve the above-described problem, the structural feature of the invention described in claim 1 is a power steering device that amplifies the steering force acting on the steering wheel by a hydraulic servo valve device and transmits the amplified steering force to the steering wheel. A handle-side shaft connected to the handle and a gear-side shaft connected to the steering gear are rotatably supported on a central axis on a housing, and the number of teeth is slightly at the opposite shaft ends of both shafts. Different first and second sun gears are provided, and a planetary gear mechanism that supports the first and second planetary gears that mesh with the first and second sun gears and supports the first and second planetary gears so as to rotate about the central axis is provided. In the variable reduction ratio type power steering apparatus that rotates the carrier by a motor and changes the reduction ratio, a valve storage hole in which the servo valve apparatus is stored; A planetary gear chamber in which the planetary gear mechanism is housed is formed adjacent to the housing, a pressure port for supplying hydraulic oil to the servo valve device is opened in the valve housing hole, and the operation from the servo valve device is performed. A return port for discharging oil is opened in the planetary gear chamber, and the planetary gear mechanism is lubricated with hydraulic oil circulating through the planetary gear chamber from the servo valve device.

  According to a second aspect of the present invention, the hydraulic fluid discharged from the servo valve device is introduced into the planetary gear chamber through the communication passage formed in the handle side shaft. It is that.

  According to a third aspect of the present invention, there is provided a structural feature of the gear chamber according to the first aspect, wherein a handle-side shaft is connected to the handle via the servo valve device, and a steering gear formed in the housing is housed. This is because the space between the planetary gear chamber and the planetary gear chamber is liquid-tightly sealed by the seal member.

  According to a fourth aspect of the present invention, there is provided a structural feature of the invention according to any one of the first to third aspects, wherein both ends of a drive shaft connected to the output shaft of the motor and transmitting rotation to the carrier are connected to the housing in the precursor planetary gear chamber. And the space between the planetary gear chamber and the motor is liquid-tightly sealed with a seal member.

  In the invention according to claim 1 configured as described above, the steering force acting on the steering wheel is amplified by the servo valve device and transmitted to the steering wheel. The rotation of the handle-side shaft connected to the handle is shifted by the planetary gear mechanism according to the rotation of the carrier whose rotation is controlled by the motor and transmitted to the steering gear, and the reduction ratio as the power steering device is changed. The oil discharged from the hydraulic servo valve device circulates through the planetary gear chamber in which the planetary gear mechanism is housed and is discharged from the return port. Therefore, the planetary gear mechanism is immersed in oil and the gear tooth surfaces and gear bearings are securely lubricated. It is possible to improve the durability by reducing friction and wear. Furthermore, gear meshing noise can be reduced by oiling the planetary gear mechanism.

  In the invention according to claim 2 configured as described above, the oil discharged from the hydraulic servo valve device is discharged from the return port through the planetary gear chamber through the communication path formed in the handle side shaft. The oil discharged from the servo valve device can be accurately introduced into the planetary gear chamber.

  In the invention according to claim 3 configured as described above, the shaft on the handle side is connected to the handle via the servo valve device, and the planetary gear chamber into which the hydraulic oil flows from the servo valve device and the gear chamber that houses the steering gear. Is sealed liquid-tightly by the seal member, so that the working oil and the grease for lubricating the steering gear are not mixed.

  In the invention according to claim 4 configured as described above, both ends of the drive shaft connected to the output shaft of the motor and transmitting the rotation to the carrier are supported by the housing in the planetary gear chamber, and the planetary gear chamber and the motor are connected to each other. Since the gap is sealed, the hydraulic oil that flows into the planetary gear chamber from the hydraulic servo valve does not flow out to the motor side.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2. In the variable reduction ratio type power steering apparatus 1 according to the embodiment of the present invention, the rotation of the handle is transmitted to the input shaft 4 of the hydraulic servo valve device 3, and the rotation of the output shaft of the servo valve device 3 is caused by the planetary gear mechanism 6. The gear is shifted and transmitted to the pinion shaft 13 of the rack and pinion mechanism 7. As a result, the steering force acting on the steering wheel is amplified by the servo valve device 3 and transmitted to the steering wheel 8 via the rack and pinion mechanism 7 which is a steering gear.

  The upper housing 9 and the lower housing 10 constituting the housing are connected by bolts. A valve storage hole 9a is formed in the upper housing 9, and the servo valve device 3 is stored in the valve storage hole 9a. A handle-side shaft 11 that is an output shaft of the servo valve device 3 is rotatably supported around the central axis O by a bearing 12 at the lower housing 10 side opening end of the valve housing hole 9a of the upper housing 9.

  A gear chamber 10a is formed in the lower housing 10, and a rack and pinion mechanism 7 as a steering gear is accommodated in the gear chamber 10a. A gear side shaft 13 which is a pinion shaft of the rack and pinion mechanism 7 is supported by the lower housing 10 so as to be rotatable around the central axis O by bearings 14 and 15.

  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 in the valve housing hole 9 a formed in the upper housing 9 so as to be rotatable around the central axis O, and the rotary valve is inserted into the valve hole 21 formed in the sleeve 20. 18 is fitted so as to be rotatable around the central axis O. The servo valve device 3 is constituted by the rotary valve 18, the sleeve 20, and the like.

  The cylinder ports SA and SB communicated with the left and right chambers 28a and 28b of the cylinder device 30 according to the relative rotation between the rotary valve 18 and the sleeve 20, respectively, are connected to the hydraulic pump and the tank, and the pressure port P and the return port T are connected to the hydraulic pump and the tank, respectively. To be connected to. The input shaft 4 and the handle side shaft 11 are coupled to both ends of the torsion bar 24, respectively. When the steering input is not applied to the steering wheel and the input shaft 4 is in a free state, the pressure port P and the return port T are communicated with each other, and the rotary valve 18 is connected to the sleeve 20 in a neutral position where no hydraulic pressure is generated in the cylinder ports SA and SB. It is rotationally positioned relative to it.

  Here, the pressure port port P and the cylinder ports SA and SB are opened in the valve housing hole 9a, and the return port T is opened in a planetary gear chamber described later. The input shaft 4 is provided with a through hole 4a through which the torsion bar 24 is inserted, and the axial space 4b formed between the through hole 4a and the torsion bar 24 is discharged from the servo valve device 3. A discharge passage through which hydraulic oil flows is configured.

  A planetary gear chamber 10b is formed on the upper housing 9 side of the lower housing 10 adjacent to a valve storage hole 9a in which the servo valve device 3 is stored, and a planetary gear mechanism 6 having a configuration described later is stored in the planetary gear chamber 10b. Has been. The planetary gear chamber 10 b communicates with an axial space portion 4 b formed in the input shaft 4 through a plurality of communication holes 11 a formed in the handle side shaft 11. A return port T communicating with the tank is opened at the upper end of the planetary gear chamber 10b. As a result, the low-pressure hydraulic oil discharged from the servo valve device 3 circulates in the space 4b in the input shaft 4, the communication hole 11a of the handle shaft 11 and the planetary gear chamber 10b and is discharged from the return port T. Thus, the planetary gear chamber 10b is filled with the oil discharged from the servo valve device 3, and the planetary gear mechanism 6 is immersed in oil.

  On the other hand, the rack and pinion mechanism 7 housed in the gear chamber 10a is lubricated with grease. In order to prevent the hydraulic oil filled in the planetary gear chamber 10b from flowing into the gear chamber 10a, the planetary gear chamber 10b and the gear chamber 10a are liquid-tightly sealed by the seal member 17.

  The handle-side shaft 11 extends into the planetary gear chamber 10b, and a small diameter portion 11b projects from the shaft end. A bearing hole 13 a is formed at the shaft end of the gear side shaft 13 that faces the handle side shaft 11, and a small diameter portion 11 b is rotatably supported by the needle bearing 16 in the bearing hole 13 a. In this way, the opposed shaft end portions of the handle-side shaft 11 and the gear-side shaft 13 have high concentricity around the central axis O through the bearing 16 that supports the radial load, and can rotate relatively with high rigidity. Is fitted.

  A sliding hole 13b is continuously drilled in the bearing hole 13a at the shaft end of the gear side shaft 13, and a friction body 45 is slidably fitted into the sliding hole 13b. The friction body 45 is a compression spring. The spring force of 46 is pressed against the end face of the small diameter portion 11 a of the handle side shaft 11. Thereby, resistance is given to relative rotation between the handle-side shaft 11 and the gear-side shaft 13.

  In the planetary gear chamber 10 b of the lower housing 10, a carrier rotation mechanism 50 that is arranged in parallel on the planetary gear mechanism 6 on the central axis O and is driven to rotate by the motor 51 is housed. First and second sun gears 34 and 35 having slightly different numbers of teeth are integrally provided at opposite shaft ends of the handle side shaft 11 and the gear side shaft 13, respectively. Plates 36a and 36b are loosely fitted on the handle-side shaft 11 and the gear-side shaft 13, and a plurality of (for example, three) planets 37 arranged at substantially equal angular intervals on the circumference are provided on the plates 36a and 36b. Each of the plates 36a and 36b is rotatably supported via a bush 39 by a support shaft 38 supported at both ends.

  Each planetary body 37 is integrally formed on the same axis with first and second planetary gears 40 and 41 which mesh with the first and second sun gears 34 and 35 and rotate integrally therewith. A carrier 36 that supports the first and second planetary gears 40 and 41 is constituted by the plates 36a and 36b, the support shaft 38, and the like. As an example, the number of teeth of the first and second sun gears 34 and 35 and the first and second planetary gears 40 and 41 is 20, 21, 21, and 20, respectively. The first and second sun gears 34 and 35, the first and second planetary gears 40 and 41, the carrier 36, and the like constitute the planetary gear mechanism 6.

  The carrier rotation mechanism 50 is provided in the planetary gear chamber 10 b adjacent to the planetary gear mechanism 6, transmits the rotational force of the motor 51 mounted on the lower housing 10 to the carrier 36, and rotates the carrier 36. It is configured to drive. The carrier rotation mechanism 50 includes a worm mechanism including a worm shaft 48 and a worm wheel 43 as main components. The worm shaft 48 is supported at both ends by bearings 52, 53 so as to be rotatable about the axis perpendicular to the central axis O to the lower housing 10, and is rotatably connected to the output shaft of the motor 51. A seal member 54 is mounted between the output shaft of the motor 51 and the lower housing 10, and the planetary gear chamber 10 b and the motor 51 are sealed by the seal member 54.

  The worm wheel 43 is engaged with a worm 44 provided on the worm shaft 48. The worm wheel 43 is made of resin and is integrally formed on the outer peripheral surface of the metal sleeve 33. The metal sleeve 33 is supported by the gear side shaft 13 along the carrier 36 so as to be rotatable around the central axis O by a bearing 42. Yes.

  A spline protrusion 33 a having a rectangular cross section is formed on the cylindrical portion protruding from one end of the metal sleeve 33. The spline projection 33a is fitted into a spline groove formed on the inner peripheral surface of the plate 36b of the carrier 36, and is configured to transmit the rotational force of the metal sleeve 33 to the carrier 36 through the spline fitting portion. ing.

  Further, a wave washer 32 as a spring member is provided between the carrier 36 and the metal sleeve 33, and the carrier 36 is urged away from the metal sleeve 33 to determine the axial position of the carrier 36.

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

  Next, the operation of the embodiment having the above configuration will be described. When the handle is rotated, the rotary valve 18 and the sleeve 20 are rotated relative to each other by twisting the torsion bar 24, and the pressure oil supplied from the pressure port P is supplied from the cylinder port SA or SB to the cylinder device according to the rotation direction of the handle. 30 is supplied to the cylinder left chamber 28a or the right chamber 28b, the rack shaft 27 is pivoted, and the steering wheel 8 is deflected.

  At this time, if the rotation of the motor 51 is stopped, the carrier 36 that rotates integrally with the worm wheel 43 is fixed and held so as not to rotate by the irreversible rotation action of the worm mechanism. Therefore, even if the input-side first sun gear 34 or the output-side second sun gear 35 rotates, the first and second planetary gears 40 and 41 only rotate, and the steering reduction ratio is maintained at a predetermined value. The

  On the other hand, when the carrier 36 is rotated through the worm mechanism by the rotation of the motor 51, the gear side shaft 13 is shifted and rotated by the planetary gear mechanism 6 according to the rotation of the carrier 36. At this time, when the carrier 36 is rotated in the same direction as the handle, the rotation ratio between the gear side shaft 13 and the handle side shaft 11 is increased according to the number of rotations, and the steering reduction ratio is reduced. The reduction ratio as a whole of the power steering apparatus is reduced. On the other hand, when the carrier 36 is rotated in the direction opposite to the handle, the reduction ratio of the entire power steering apparatus is increased.

  Therefore, in conjunction with the turning of the steering wheel, the rotational direction and the rotational speed of the motor 51 are adjusted so that the reduction ratio of the power steering apparatus as a whole becomes an optimum value for the traveling state of the vehicle by an electronic control device (not shown). And the rotation of the motor 51 is transmitted to the worm shaft 48, and the worm 44 rotates the worm wheel 43. The worm wheel 43 rotates the carrier 36 of the planetary gear mechanism 6 and controls the steering reduction ratio to an optimum value for the running state of the vehicle.

  By the way, the hydraulic oil supplied from the hydraulic pump to the servo valve device 3 via the pressure port P is supplied to one cylinder chamber of the cylinder device 30 according to the turning direction of the handle and discharged from the other cylinder chamber. The hydraulic oil is discharged from the servo valve device 3 to the space 4b in the input shaft 4, and further circulated in the planetary gear chamber 10b through the communication hole 11a formed in the handle side shaft 11, and discharged from the return port T to the tank. Is done.

  Thus, since the planetary gear chamber 10b constitutes a part of the hydraulic oil circulation passage of the power steering apparatus 1, the planetary gear chamber 10b is filled in 80% by the low-pressure hydraulic oil that returns to the tank. The gear mechanism 6 is immersed in oil. Thereby, the gear tooth surfaces and the gear bearing portions of the planetary gear mechanism 6 and the worm mechanism are reliably lubricated, and the friction and wear are reduced and the durability is improved. Furthermore, since the planetary gear mechanism 6 is immersed in oil, gear meshing noise is reduced.

  When the gear side shaft 13 is rotated by the handle side shaft 11 via the planetary gear mechanism 6, the friction body 45 is pressed against the small diameter portion 11 a by the spring force of the compression spring 46. It resists relative rotation with the shaft 13, reduces play due to gear backlash, improves steering feel, and increases rigidity when the steering wheel is neutral.

  In the embodiment described above, the rotation of the handle is transmitted to the input shaft 4 of the hydraulic servo valve device 3, and the rotation of the output shaft of the servo valve device 3 is shifted by the planetary gear mechanism 6 and transmitted to the rack and pinion mechanism 7. Although the configuration has been described, the arrangement of the hydraulic servo valve device 3 and the planetary gear mechanism 6 disposed between the handle and the rack and pinion mechanism 7 is reversed, and the rotation of the handle is first shifted by the planetary gear mechanism 6. Thereafter, the signal can be amplified by the hydraulic servo valve device 3.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view of a variable reduction ratio type power steering apparatus according to a first embodiment. Sectional drawing cut | disconnected along the AA line of FIG. Sectional drawing cut | disconnected along the BB line of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Variable reduction ratio type power steering device, 3 ... Hydraulic servo valve device, 4 ... Input shaft, 6 ... Planetary gear mechanism, 7 ... Rack and pinion mechanism (steering gear), 8 ... Steering wheel, 9 ... Upper housing, DESCRIPTION OF SYMBOLS 9a ... Valve storage chamber, 10 ... Lower housing, 10a ... Gear chamber, 10b ... Planetary gear chamber, 11 ... Handle side shaft, 13 ... Gear side shaft, 17 ... Seal member, 18 ... Rotary valve, 24 ... Torsion bar, 27 ... rack shaft, 30 ... cylinder device, 34, 35 ... first and second sun gears, 36 ... carrier, 40, 41 ... first and second planetary gears, 43 ... worm wheel, 44 ... worm, 51 ... motor, P, T, SA, SB ... port.

Claims (4)

A power steering device that amplifies a steering force acting on the steering wheel by a hydraulic servo valve device and transmits the amplified steering force to the steering wheel, a steering wheel side shaft connected to the steering wheel, and a gear side shaft connected to the steering gear, The first and second sun gears having slightly different teeth are provided at opposite shaft ends of the two shafts, and meshed with the first and second sun gears, respectively. A planetary gear mechanism is configured by supporting a carrier supporting the first and second planetary gears that rotate integrally so as to be rotatable about the central axis, and a reduction ratio variable power that changes the reduction ratio by rotationally driving the carrier by a motor. In the steering apparatus, a valve housing hole in which the servo valve device is housed and a planetary gear chamber in which the planetary gear mechanism is housed are adjacent to the housing. Forming a pressure port for supplying hydraulic oil to the servo valve device in the valve housing hole, opening a return port for discharging the hydraulic oil from the servo valve device in the planetary gear chamber, and the servo valve device. The planetary gear mechanism is lubricated with hydraulic fluid that circulates through the planetary gear chamber. 2. The variable speed ratio variable power steering apparatus according to claim 1, wherein hydraulic oil discharged from the servo valve device is introduced into the planetary gear chamber through a communication passage formed in the handle side shaft. 2. The liquid-tight seal according to claim 1, wherein the handle-side shaft is coupled to the handle via the servo valve device, and a seal member is provided between the gear chamber housing the steering gear formed in the housing and the planetary gear chamber. A variable ratio reduction type power steering device that is sealed. 4. The drive shaft connected to the output shaft of the motor and transmitting rotation to the carrier is supported by the housing in the precursor planetary gear chamber according to claim 1, and the planetary gear chamber and the motor are A reduction ratio variable type power steering apparatus, characterized in that a gap is sealed liquid-tightly by a seal member.

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