JP2005238947A - Hydraulic power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain surely comfortable steering feeling. <P>SOLUTION: A hydraulic power steering device changes a steering assist force according to the operation state of a vehicle speed. In the hydraulic power steering device, a hydraulic control valve 30 controls the hydraulic pressure of the pressurized oil supplied to the hydraulic actuator 20 for generating the steering assist force according to an elastic relative rotation amount of input/output shafts 2, 3 responding to the steering torque. A pressed part 51 which rotates along with the one side of the input/output shafts 2, 3 is constituted so that the pressing force is controlled by the pressing part 52 which rotates along with the other side according to the operation state of the vehicle. The pressed part 51 is constituted of the inside surface relatively facing to the groove, and the both inside surfaces proximate to each other as they go toward the groove center. The pressing part 52 has a rolling bearing 53 and a support member supporting the rolling bearing 53, and the outer periphery of the outer ring of the rolling bearing 53 is pressed to both inside surface of the groove. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a hydraulic power steering apparatus capable of changing a steering assist characteristic in accordance with a driving state such as a vehicle speed.

Hydraulic power steering equipped with a control valve that controls the hydraulic pressure of the pressure oil supplied to the hydraulic actuator for generating steering assist force according to the amount of elastic relative rotation through the torsion bar of the input shaft and output shaft according to the steering torque In the apparatus, the steering assist characteristic can be changed according to the steering torque. In such a hydraulic power steering device, there is known one provided with a regulating means for regulating the relative rotation of the input / output shaft according to the driving state of the vehicle. The restricting means includes a pressed portion that rotates together with one side of the input / output shaft, and a direction that rotates together with the other side of the input / output shaft and moves away from the pressed portion. A pressing part capable of reciprocating, an output mechanism that causes the pressing part to act on the pressing part, and a control device that controls the generated force of the output mechanism in accordance with the driving state of the vehicle (see Patent Document 1) . As a result, the steering assist force is changed by regulating the relative rotation amount of the input / output shaft according to the driving state such as the vehicle speed, and the driving stability at high vehicle speed and the response to steering at low vehicle speed are improved. Can do.
JP-A-6-321124

  In the conventional hydraulic power steering apparatus, the pressing portion is constituted by a ball, the pressed portion is constituted by inner surfaces facing each other of the groove, and both inner surfaces are close to each other toward the groove center. Therefore, there is a problem that the rolling of the ball is hindered by the friction with the inner surface of the groove during the relative rotation of the input / output shaft, and the steering feeling is lowered. An object of the present invention is to provide a hydraulic power steering apparatus that can solve such a problem.

The present invention includes an input shaft, an output shaft that is coaxially connected to the input shaft via an elastic member so as to elastically rotate relative to the input shaft, a steering assist force generating hydraulic actuator, A control valve for controlling the hydraulic pressure of the pressure oil supplied to the hydraulic actuator according to the relative rotation amount of the input / output shaft; and a regulating means for regulating the relative rotation of the input / output shaft according to a driving state of the vehicle. The restricting means includes a pressed portion that rotates together with one side of the input / output shaft, and a direction that rotates along with the other side of the input / output shaft and approaches the pressed portion. A pressing portion capable of reciprocating in a separating direction; an output mechanism that causes the pressing portion to act on the pressing portion; and a force generated by the output mechanism. In the hydraulic power steering device, the pressed portion is configured by inner surfaces facing each other of the groove, and both inner surfaces are close to each other toward the center of the groove. The pressing portion includes a rolling bearing and a support member that supports the rolling bearing, and the outer periphery of the outer ring of the rolling bearing is pressed against both inner side surfaces of the groove.
According to the present invention, since the outer periphery of the outer ring of the rolling bearing that constitutes the pressing portion is pressed against the inner surface of the groove that constitutes the pressed portion, the contact between the pressing portion and the pressed portion is ensured by the rolling of the outer ring. As a rolling contact, friction can be reduced.

  ADVANTAGE OF THE INVENTION According to this invention, in the hydraulic power steering apparatus which changes steering assist force according to driving | running states, such as a vehicle speed, a favorable steering feeling can be obtained reliably.

  A rack and pinion type hydraulic power steering apparatus 1 according to the first embodiment shown in FIG. 1 includes an input shaft 2 coupled to a steering wheel (not shown) of a vehicle, and an input shaft 2 that is elastically coaxially centered according to a steering torque. And an output shaft 3 connected coaxially via a torsion bar (elastic member) 6 so as to rotate relative to each other. The torsion bar 6 passes through the input shaft 2, is connected to the input shaft 2 via a pin 4, and is connected to the output shaft 3 via a serration 5. One end side of the input shaft 2 is supported by the housing 7 via a bearing 8. The other end side of the input shaft 2 is inserted into a recess formed at the end portion on the one end side of the output shaft 3 and is supported via the bush 12 by the inner periphery of the recess. The output shaft 3 is rotatably supported by the housing 7 via bearings 10 and 11. A pinion 15 is integrally formed on the outer periphery of the other end of the output shaft 3, and wheels (not shown) are connected to a rack 16 that meshes with the pinion 15. Thereby, the rotation of the input shaft 2 by steering is transmitted to the pinion 15 through the torsion bar 6, the rack 16 moves in the vehicle width direction by the rotation of the pinion 15, and the steering angle of the vehicle changes by the movement of the rack 16. To do. Oil seals 17 and 18 are provided between the input shaft 2 and the housing 7 and between the output shaft 3 and the housing 7. The support yoke 40 that supports the rack 16 is pressed against the rack 16 by the elasticity of the spring 41.

  A hydraulic cylinder 20 is provided as a steering assist force generating hydraulic actuator. The hydraulic cylinder 20 includes a cylinder tube integrated with the housing 7 and a piston 21 integrated with the rack 16. Oil chambers 22 and 23 partitioned by the piston 21 are formed in the cylinder tube.

  A rotary hydraulic control valve 30 that controls the hydraulic pressure of the pressure oil supplied to the hydraulic cylinder 20 according to the relative rotation amount of the input shaft 2 and the output shaft 3 is provided. The control valve 30 includes a cylindrical first valve member 31 that is rotatably inserted into the housing 7, and a second valve member 32 that is inserted into the first valve member 31 so as to be relatively rotatable about a coaxial center. Yes. The first valve member 31 is connected to the output shaft 3 via a pin 33 so as to rotate along the same axis. The second valve member 32 is integrally formed on the outer periphery of the input shaft 2, whereby the second valve member 32 rotates along the same axis as the input shaft 2. The housing 7 is connected to a port connected to the pressure oil discharge pump 42, a port connected to the tank 43, a port connected to one oil chamber 22 of the hydraulic cylinder 20, and the other oil chamber 23. The ports communicate with each other via an inter-valve flow path 27 between the first valve member 31 and the second valve member 32. The opening degree of the throttle portion in the inter-valve flow path 27 changes according to the relative rotation amount of the input / output shafts 2 and 3. For example, as shown in FIG. 2, between the axial edges of the plurality of first grooves 48 on the inner periphery of the first valve member 31 and the axial edges of the plurality of second grooves 49 on the outer periphery of the second valve member 32. Are the aperture portions A, B, C, and D. The first grooves 48 communicating with one oil chamber 22 and the first grooves 48 communicating with the other oil chamber 23 are alternately arranged in the circumferential direction. The second grooves 49 that communicate with the pump 42 and the second grooves 49 that communicate with the tank 43 via the through holes 2 a formed in the input shaft 2 and between the torsion bar 6 and the input shaft 2 are alternately arranged in the circumferential direction. Is done. Thereby, the hydraulic circuit shown in FIG. 3 is configured. When the steering is not performed, the throttle portions A, B, C, and D are opened and the hydraulic pressure does not increase, so that the steering assist force is not generated. During right steering, the apertures of the throttles A and D are increased according to the relative rotation amounts of the input shaft 2 and the output shaft 3, and the apertures of the throttles B and C are decreased. Oil is supplied, the oil flows back to the tank 43 from the other oil chamber 23, and the hydraulic cylinder 20 generates a steering assist force in the right direction corresponding to the relative rotation amount. During left steering, the apertures of the throttles A, B, C, and D are opposite to those during right steering, and the hydraulic cylinder 20 generates a steering assist force in the left direction corresponding to the relative rotation amount.

  A restricting means 50 for restricting the relative rotation of the input shaft 2 and the output shaft 3 according to the driving state of the vehicle is provided. As shown in FIGS. 4 to 8, the regulating means 50 includes a pressed portion 51, a pressing portion 52, an output mechanism 60, and a control device 67.

  The pressed portion 51 is configured by opposed inner surfaces of grooves 31 ′ formed at four circumferentially spaced positions on the upper surface of the ring member 51 a that is fixed to the upper portion of the first valve member 31 by press-fitting or the like. Is done. As a result, the pressed portion 51 rotates along with the output shaft 3. The longitudinal direction of the groove 31 ′ is along the radial direction of the input / output shafts 2, 3, and is V-shaped when the input / output shafts 2, 3 are viewed in the radial direction. As a result, both inner side surfaces of the groove 31 'approach each other toward the center of the groove 31'.

  The pressing portion 52 rotates along with the input shaft 2 and can reciprocate in a direction approaching and separating from the pressed portion 51. That is, the pressing portion 52 includes a rolling bearing 53 constituted by the same number of ball bearings as the grooves 31 ′ and a support member 54 that supports these rolling bearings 53. The support member 54 has a stepped cylindrical shape having a small diameter portion 54a and a large diameter portion 54b, and the input shaft 2 is inserted into the center hole thereof. Support shafts 54c extending in the radial direction are fixed at four positions on the outer periphery of the small-diameter portion 54a at equal intervals in the circumferential direction, and the inner ring 53a of the rolling bearing 53 is fitted to each support shaft 54c. The tip of the support shaft 54 c has a diameter larger than that of the base end to prevent the rolling bearing 53 from coming off. As a result, the outer ring 53 b of each rolling bearing 53 rotates around the axis along the radial direction of the input / output shafts 2 and 3. Between a plurality of axial grooves 2 ″ provided on the outer periphery of the input shaft 2 at circumferential intervals and a plurality of axial grooves 54 ″ provided on the inner periphery of the support member 54 at circumferential intervals. When the ball 55 held by the retainer is sandwiched between the support member 54 and the input shaft 2, the support member 54 rotates in the same direction as the input shaft 2 and is movable in the axial direction relative to the input shaft 2. A compression coil spring 56 for preventing rattling of the support member 54 is fitted to the input shaft 2 between the upper end of the support member 54 and the upper inner surface of the housing 7. The space between the outer periphery of the support member 54 and the inner periphery of the housing 7 and the space between the inner periphery of the support member 54 and the outer periphery of the input shaft 2 are sealed in an oil-tight manner via seal members 58a and 58b, respectively. . Thereby, the oil chamber 59 is formed between the support member 54 and the upper part of the housing 7, and the support member 54 functions as a piston.

  The output mechanism 60 causes the pressing portion 52 to exert a force pressing the pressed portion 51. With this force, the outer periphery of the outer ring 53b of the rolling bearing 53 is pressed against both inner side surfaces of the groove 31 '. The generated force of the output mechanism 60 is controlled by the control device 67 according to the driving state of the vehicle. As shown in FIG. 7, the output mechanism 60 of this embodiment includes a cylindrical sleeve 62 inserted so as not to rotate relative to a holding hole 61 formed in the housing 7, and a relative rotation about the axis of the sleeve 62. The spool 63 is inserted so as to be able to be inserted. A pressure oil introduction port 62 a communicating with the pump 42 via the control valve 30 and a pressure oil delivery port 62 b communicating with the oil chamber 59 are formed in the sleeve 62. An outer peripheral groove 63a that communicates with the pressure oil introduction port 62a, a through hole 63b that is disposed at a position overlapping the pressure oil delivery port 62b, a pressure oil passage 63c that connects the outer peripheral groove 63a and the through hole 63b, and a passage through the spool 63. A throttle passage 63d that connects the hole 63b to the holding hole 61 is formed. The inside of the holding hole 61 communicates with the tank 43 through the drain channel 63e. As shown in FIG. 8, the overlapping portion (shown by hatching) of the pressure oil delivery port 62b of the sleeve 62 and the through-hole 63b of the spool 63 forms a variable throttle 60a. It changes according to the amount of rotation. The spool 63 is connected to the motor 66 via the speed reduction mechanism 65, and the rotation amount of the motor 66 is controlled by the control device 67. For example, a stepping motor can be used as the motor 66. The control device 67 controls the motor 66 according to a signal from a sensor that detects the driving state of the vehicle. The control device 67 of the present embodiment controls the motor 66 so that the opening degree of the variable throttle 60a increases as the vehicle speed increases, based on the vehicle speed signal from the sensor that detects the vehicle speed as the driving state of the vehicle. In other words, the hydraulic pressure applied to the support member 54 is increased by increasing the opening degree of the variable throttle 60a during high-speed traveling, and the restriction force on the relative rotation of the input / output shafts 2 and 3 is increased. As the vehicle speed decreases, the opening of the variable throttle 60a is reduced to reduce the hydraulic pressure applied to the support member 54, thereby relaxing the relative rotation of the input / output shafts 2 and 3. As a result, when the vehicle speed is high, an increase in the steering assisting force generation hydraulic pressure corresponding to the relative rotation amount of the input shaft 2 and the output shaft 3 is restricted, and traveling stability is achieved. At low vehicle speeds, the steering assisting force generation hydraulic pressure is increased. The regulation of the increase is eased and high response of steering is achieved.

  According to the above embodiment, the outer periphery of the outer ring 53b of the rolling bearing 53 that constitutes the pressing portion 52 is pressed against the inner surface of the groove 31 ′ that constitutes the pressed portion 51, so that the pressing portion 52 is rolled by the rolling of the outer ring 53b. And the pressed part 51 can be reliably rolled to reduce friction.

  9 to 12 show a second embodiment of the present invention, which has a restricting means 150 different from the restricting means 50 of the first embodiment. Hereinafter, the same parts in the second embodiment as those in the first embodiment are denoted by the same reference numerals, description thereof will be omitted, and differences will be described.

  The pressed portion 151 of the restricting means 150 in the second embodiment is an inner surface opposite to the groove 2 ′ formed at four positions at equal intervals in the circumferential direction of the input shaft 2 below the first valve member 31. Consists of. As a result, the pressed portion 151 rotates together with the input shaft 2. The longitudinal direction of the groove 2 'is along the axial direction of the input shaft 2, and is V-shaped when the input / output shafts 2, 3' are viewed in the axial direction. Thereby, both inner side surfaces of the groove 2 'come closer to each other toward the center of the groove 2'.

  The pressing portion 152 rotates along with the output shaft 3 ′ and can reciprocate in a direction approaching and separating from the pressed portion 151. That is, the pressing portion 152 includes a rolling bearing 153 configured by the same number of ball bearings as the grooves 2 ′ and a support member 154 that supports each rolling bearing 153. Each support member 154 has a support shaft 154b that is supported at both ends in a recess 154a that is open at one end along the cylindrical surface.

  The output shaft 3 'in the second embodiment has a main body 3a and an annular member 3b fitted concentrically to the outer periphery of the main body 3a. Similarly to the output shaft 3 of the first embodiment, the main body 3 a is connected to the input shaft 2 via the torsion bar 6 and is connected to the first valve member 31 via the pin 33. The same number of guide holes 155 as support members 154 are formed in the annular member 3b. The inner periphery of each guide hole 155 is along the cylindrical surface, and its axis is along the radial direction of the input / output shafts 2, 3 '. One end of each guide hole 155 opens so as to face both inner side surfaces of the groove 2 ′ through a through hole 3 a ′ formed in the main body 3 a, and the other end faces the inner peripheral surface of the housing 7. Open. The through hole 3a ′ of the main body 3a has a larger diameter than the guide hole 155.

  Each support member 154 is inserted into the guide hole 155 and the through hole 3a ′ so as to be movable in the radial direction of the input / output shafts 2 and 3 ′. As a result, the pressing portion 152 can reciprocate in the direction approaching and separating from the pressed portion 151. The inner ring 153a of the rolling bearing 153 is fitted to each support shaft 154b. As a result, the outer ring 153b of each rolling bearing 153 rotates around the axis offset in the axial direction of the input / output shafts 2, 3 '.

  A plunger 156 is inserted into each guide hole 155 between the support member 154 and the housing 7. Each plunger 156 can reciprocate along the radial direction of the input / output shafts 2, 3 '. The outer periphery of each plunger 156 is assumed to be along the cylindrical surface. Between the inner periphery of the guide hole 155 and the outer periphery of the plunger 156, a steel ball 158 held by a retainer is interposed as a friction reducing member. An oil seal may be interposed between the inner periphery of the guide hole 155 and the outer periphery of the plunger 156. A pair of seal members 159 and 160 that seal the gap between the outer periphery of the output shaft 3 ′ and the inner periphery of the housing 7 in an oil-tight manner are provided at intervals in the axial direction, and each plunger is interposed between the seal members 159 and 160. 156 is arranged. As a result, an oil chamber 161 is formed between the other end of each plunger 156 and the inner periphery of the housing 7, and each oil chamber 161 communicates via a circumferential groove 3 a ″ formed on the outer periphery of the output shaft 3 ′. 9, the oil chamber 161 is connected to the pump 42 through the same output mechanism 60 as in the above embodiment, whereby the control device 67 increases the opening of the variable throttle 60a during high-speed travel. As a result, the hydraulic pressure applied to the support member 154 via the plunger 156 is increased, and the restricting force of relative rotation of the input / output shafts 2 and 3 'is increased, and the opening degree of the variable throttle 60a is decreased as the vehicle speed decreases. The hydraulic pressure applied to the support member 154 via the plunger 156 is reduced, and the restriction on the relative rotation of the input / output shafts 2 and 3 'is relaxed, whereby the input shaft 2 and the output shaft are driven at high vehicle speeds. The increase of the steering assist force generation hydraulic pressure according to the relative rotation amount of ′ is regulated to improve running stability, and at low vehicle speed, the increase control of the steering assist force generation hydraulic pressure is relaxed and the steering responsiveness is improved. Figured.

  When the steering torque is not acting, the center axis of the rolling bearing 153 constituting the pressing portion 152 and the center position of the groove 2 'constituting the pressed portion 151 are relatively in the radial direction of the input / output shafts 2, 3'. As shown in FIG. 10, a screw 3c is provided as a member for preventing relative rotation of the center of the annular member 3b with respect to the main body 3a as shown in FIG. The relative rotation of the annular member 3b with respect to the main body 3a by the screw 3c is performed after the input shaft 2 is connected to the main body 3a via the torsion bar 6. The connection between the input shaft 2 and the main body 3a via the torsion bar 6 is performed after positioning the relative positions of the input / output shafts 2, 3 'in the relative rotation direction so that a desired hydraulic control characteristic can be obtained by the control valve 30. . That is, the degree of opening of each of the throttle portions A, B, C, and D changes inversely symmetrically as described above when the left steering is performed and the right steering is performed from the state where the steering torque is not applied. The relative positions of the input / output shafts 2, 3 ′ are positioned in the relative rotational direction, and then the torsion bar 6 connected to the main body 3 a via the serration 5 is connected to the input shaft 2 via the pin 4.

  When the central axis of the rolling bearing 153 and the central position of the groove 2 'are opposed to each other in the radial direction of the input / output shafts 2, 3', the outer ring 153b of the rolling bearing 153 is in contact with both inner surfaces of the groove 2 '. Therefore, for example, by pressing the outer ring 153b against both inner side surfaces of the groove 2 'by applying hydraulic pressure to the plunger 156, the annular member 3b is rotated relative to the main body 3a about the axis, and the center axis of the rolling bearing 153 is set. And the relative position of the center of the groove 2 'can be performed. After the positioning, the screw 3c is screwed into the screw hole 3d of the main body 3a through the through hole 3b 'of the annular member 3b. As shown in FIG. 12, the through-hole 3b 'is a long hole whose circumferential direction is a longitudinal direction so as to allow relative rotation of the axial center of the annular member 3b with respect to the main body 3a, and a step for receiving the head of the screw 3c. Thus, when no steering torque is applied, the central axis of the rolling bearing 153 and the central position of the groove 2 'are opposed to each other in the radial direction of the input / output shafts 2, 3', and the steering angle is increased. The hydraulic pressure to be changed is not generated, and the rest is the same as in the second embodiment, as a means for preventing the relative rotation of the axial center of the annular member 3b with respect to the main body 3a, as shown in FIG. A split portion 3e is provided on the lower end side of the annular member 3b, and a screw 3f that is screwed into a screw hole that opens at the opposite end face of the split portion 3e is used to reduce the interval between the split portions 3e and apply the tightening force of the main body 3a. May be allowed

  The present invention is not limited to the above embodiment. For example, the rolling bearing constituting the pressing portion is not limited to a ball bearing, and may be a roller bearing or a needle bearing. The output mechanism is not limited to one that applies a force by hydraulic pressure, and a force that presses the pressed portion may be applied to the pressing portion by an electric actuator that moves according to the driving state of the vehicle. Further, the hydraulic pressure may be adjusted by a hydraulic pressure adjusting mechanism according to, for example, a steering angle other than the vehicle speed as the driving state of the vehicle. The present invention can also be applied to hydraulic power steering devices other than the rack and pinion type. For example, the output shaft is integrated with the ball screw shaft, and the ball nut screwed to the ball screw shaft is integrated with the piston of the hydraulic cylinder for generating steering assist force. The present invention may be applied to a ball screw type hydraulic power steering apparatus.

1 is a longitudinal sectional view of a hydraulic power steering apparatus according to a first embodiment of the present invention. 1 is a cross-sectional view of a control valve in a hydraulic power steering apparatus according to a first embodiment of the present invention. Hydraulic circuit in hydraulic power steering apparatus of first embodiment of the present invention The longitudinal cross-sectional view of the principal part in the hydraulic power steering device of 1st Embodiment of this invention VV line sectional view of FIG. The partial expanded side sectional view in the hydraulic power steering device of an embodiment of the present invention Sectional drawing of the output mechanism in the hydraulic power steering apparatus of embodiment of this invention Action explanatory drawing of the output mechanism in the hydraulic power steering device of the embodiment of the present invention The longitudinal cross-sectional view of the hydraulic power steering device of 2nd Embodiment of this invention The longitudinal section of the important section in the hydraulic power steering device of a 2nd embodiment of the present invention. XI-XI line sectional view of FIG. The partial side view in the hydraulic power steering device of a 2nd embodiment of the present invention. The partial cross-sectional view in the hydraulic power steering device which concerns on the modification of this invention

Explanation of symbols

2 Input shaft 2 'Groove 3, 3' Output shaft 6 Torsion bar (elastic member)
20 Hydraulic cylinder (hydraulic actuator for generating steering assist force)
30 Control valve 31 'Groove 50, 150 Restricting means 51, 151 Pressed portion 52, 152 Pressed portion 53, 153 Rolling bearing 53b, 153b Outer ring 54, 154 Support member 60 Output mechanism 67 Control device

Claims (1)

An input shaft;
An output shaft coupled to the input shaft coaxially through an elastic member so as to elastically rotate relative to the steering torque; and
A hydraulic actuator for generating steering assist force;
A control valve for controlling the hydraulic pressure of the pressure oil supplied to the hydraulic actuator according to the relative rotation amount of the input / output shaft;
A regulation means for regulating the relative rotation of the input / output shaft according to the driving state of the vehicle,
The restricting means is rotated with the other side of the input / output shaft while being rotated with the one side of the input / output shaft, and is spaced apart from a direction close to the pressed portion. A pressing portion that can reciprocate in a direction, an output mechanism that causes the pressing portion to act on the pressing portion, and a control device that controls the generated force of the output mechanism in accordance with a driving state of the vehicle. And
In the hydraulic power steering device, the pressed portion is configured by inner surfaces facing each other of the groove, and both inner surfaces approach each other toward the groove center.
The pressing portion includes a rolling bearing and a support member that supports the rolling bearing,
The hydraulic power steering apparatus, wherein an outer periphery of an outer ring of the rolling bearing is pressed against both inner side surfaces of the groove.

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