JP2005247290A - Hydraulic power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To vary the steering auxiliary characteristic according to a driving state of a vehicle without requiring a complex structure or reducing steering feeling. <P>SOLUTION: A hydraulic control valve 30 controls the oil pressure of pressure oil supplied to a hydraulic actuator 20 for generating a steering auxiliary force according to an elastic relative rotation amount of input/outputs 2 and 3 according to the steering torque. A moving mechanism 50 has a moving body 51 moving by an amount according to the driving state of the vehicle. An elastic member 70 generates an elastic force for regulating a relative rotation of the input/outputs 2 and 3 according to the relative rotation amount. A rigidity adjusting mechanism 80 adjusts the rigidity of the elastic member 70 so that the generated elastic force of the elastic member 70 changes according to the moving amount of the moving body 51. <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.

  In a hydraulic power steering apparatus including a hydraulic control valve that controls the hydraulic pressure of pressure oil supplied to a hydraulic actuator for generating steering assist force according to the elastic relative rotational amount of an input shaft and an output shaft according to a steering torque. The steering assist characteristic can be changed according to the steering torque. In such a hydraulic power steering device, by changing the steering assist force according to the driving state such as the vehicle speed, it is possible to improve the running stability at a high vehicle speed and the responsiveness to the steering at a low vehicle speed. Yes.

For example, in a hydraulic power steering apparatus including a rotary hydraulic control valve that controls oil pressure according to the relative rotation amount of an outer side valve component and an inner side valve component due to torsion bar twisting, the twist angle of the torsion bar Is converted to the relative rotation angle of both valve components, a conversion mechanism is provided for changing the conversion rate according to the vehicle speed (see Patent Document 1), and the rotation of the valve component on the outer side is determined according to the vehicle speed. It has been proposed to provide a load applying device that applies a load to be regulated from the shaft axial direction via a rolling bearing (see Patent Document 2).
JP-A-7-117694 Japanese Patent Laid-Open No. 10-16805

  The conversion mechanism that changes the conversion rate between the torsion angle of the torsion bar and the relative rotation angle of both valve components includes a plurality of spherical bearings that support pins that transmit the relative rotation, and a mechanism that changes the support position. Since the conversion rate is changed by changing the support position, the structure becomes extremely complicated, and the weight and cost increase. When a load that restricts the rotation of the valve component is applied via the rolling bearing, the steering feeling is reduced due to friction and play between the bearing components. It is an object of the present invention to provide a hydraulic power steering apparatus that can solve such problems of the prior art.

The hydraulic power steering device according to the present invention supplies an input shaft, an output shaft connected to the input shaft so as to be elastically rotatable relative to the input shaft, a steering assist force generating hydraulic actuator, and the hydraulic actuator A hydraulic control valve that controls the hydraulic pressure of the pressurized oil according to the relative rotation amount of the input / output shaft, a moving mechanism that has a moving body that moves by an amount according to the driving state of the vehicle, An elastic member that generates an elastic force that restricts relative rotation according to the amount of relative rotation, and a rigidity adjustment mechanism that adjusts the rigidity of the elastic member so that the elastic force changes according to the amount of movement of the moving body. Prepare.
According to the present invention, the input / output shaft is relatively rotated by the action of the steering torque, the relative rotation of the input / output shaft is regulated by the elastic force generated by the elastic member, and the rigidity of the elastic member is an amount corresponding to the driving state of the vehicle. It is adjusted by the movement of the moving body. Therefore, the relative rotation amount of the input / output shaft changes according to the driving state of the vehicle, and the hydraulic pressure for generating the steering assist force controlled by the hydraulic control valve changes. It is preferable that the moving mechanism has a hydraulic pressure adjusting mechanism that adjusts the hydraulic pressure according to the driving state of the vehicle, and the moving body is moved according to the hydraulic pressure adjusted by the hydraulic adjusting mechanism.

  The moving body is axially moved with respect to the input / output shaft and connected to one of the input / output shafts so as to rotate together. The elastic member is a position eccentric from the axis of the input / output shaft. A fixed end that rotates together with the other of the input / output shafts, and a free end that is separated from the fixed end in the axial direction of the input / output shaft, and the rigidity adjusting mechanism rotates together with the movable body and has a shaft. A pressing portion that moves in the same direction, and the pressing portion is disposed at a position where the elastic member is pressed by relative rotation of the input / output shaft, and the elastic member is elastically deformed by the pressing of the pressing portion. The elastic force is generated, and the bending rigidity of the elastic member changes according to the change of the pressing position by the pressing portion in the axial direction of the input / output shaft. Masui. Accordingly, an elastic member that generates elasticity by bending deformation in the relative rotation direction of the input / output shaft can be used.

  The moving body includes a first moving body piece and a second moving body piece that move in the axial direction with respect to the input / output shaft and are disposed relative to each other at an interval in the axial direction of the input / output shaft, The first moving body piece and the second moving body piece move in directions opposite to each other by an amount corresponding to a driving state of the vehicle, and the rigidity adjusting mechanism is arranged between the input shaft and the output between the two moving body pieces. The elastic member is disposed between the first movable body piece and the displacement member. A first spring piece disposed, and a second spring piece disposed between the second moving body piece and the displacement member, and the displacement member is moved by the relative rotation of the input / output shaft. Axially displaced with respect to the output shaft, The elastic force is generated by elastic deformation along the axial direction of the input / output shaft of each spring piece due to the position, and each spring piece is longitudinally elastic according to the amount of elastic deformation along the axial direction of the input / output shaft. It is preferably a non-linear spring whose coefficient changes. Accordingly, an elastic member that generates elasticity by the axial deformation of the input / output shaft can be used. Further, when the moving body is moved according to the magnitude of the adjustment hydraulic pressure by the hydraulic pressure adjusting mechanism, the moving body can be displaced to a position where the hydraulic pressure for displacing the moving body and the elasticity of the elastic member are balanced.

  The movable body is axially moved with respect to the input / output shaft and connected to one of the input / output shafts so as to rotate together. The rigidity adjusting mechanism is accompanied with the other of the input / output shafts. The elastic member has a receiving portion that is rotated and spaced apart from the moving body in the axial direction of the input / output shaft, and the elastic member is connected to the moving body to rotate together with the one end portion and the The other end connected to the receiving portion so as to rotate together with the receiving portion, and is compressed between the moving body and the receiving portion, and the elastic member is elastically moved by relative rotation of the input / output shaft. It is preferable that the elastic force is generated by torsional deformation, and the torsional rigidity of the elastic member changes according to a change in the compression amount in the axial direction of the input / output shaft between the moving body and the receiving portion. Accordingly, an elastic member that generates elasticity by torsional deformation in the relative rotational direction of the input / output shaft can be used. In addition, since the relative rotation of the input / output shaft can be directly converted into the torsional deformation of the elastic member, the structure can be simplified. In this case, it is preferable to provide a blocking portion for blocking deformation of the elastic member in the radial direction of the input / output shaft. Thereby, it is possible to prevent the change in torsional rigidity according to the change in the axial compression amount of the elastic member from being suppressed by the radial deformation, increase the material selection range of the elastic member and increase the degree of freedom of design, The running stability can be improved by increasing the rigidity during high-speed straight running. Further, when the moving body is moved according to the magnitude of the adjustment hydraulic pressure by the hydraulic pressure adjusting mechanism, the moving body can be displaced to a position where the hydraulic pressure for displacing the moving body and the elasticity of the elastic member are balanced.

  According to the hydraulic power steering device of the present invention, the weight and cost can be reduced by changing the steering assist characteristic according to the driving state of the vehicle without requiring a complicated structure and without lowering the steering feeling. It can be reduced and the running stability can be improved.

  A rack and pinion type hydraulic power steering apparatus 1 according to the first embodiment of the present invention shown in FIG. 1 includes an input shaft 2 connected to a steering wheel (not shown) of a vehicle, and the input shaft 2 is elastic according to a steering torque. And an output shaft 3 connected coaxially via a torsion bar 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 by a pin 4, and is connected to the output shaft 3 through 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 supported by the inner periphery of the recess via the bush 12. 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 includes a port 42 a connected to the pressure oil discharge pump 42, a port 43 a connected to the tank 43, a port 22 a connected to one oil chamber 22 of the hydraulic cylinder 20, and the other oil chamber 23. Ports 22b connected to each other are provided, and each port communicates 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, the control valve 30 includes axial edges of the plurality of first grooves 48 on the inner periphery of the first valve member 31 and shafts of the plurality of second grooves 49 on the outer periphery of the second valve member 32. Apertures A, B, C, and D are defined between the direction edges. 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 are alternately arranged in the circumferential direction. The second groove 49 communicating with the tank 43 has a port 43a connected to the tank 43 via the oil passage 2a formed in the input shaft 2 and between the outer periphery of the torsion bar 6 and the inner periphery of the input shaft 2. Leads to 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 moving mechanism 50 having a moving body 51 that moves by an amount corresponding to the driving state of the vehicle is provided. The moving body 51 of the present embodiment is connected so as to move in the axial direction with respect to the input / output shafts 2 and 3 and to rotate together with the input shaft 2, and relatively rotates with respect to the output shaft 3, so that the vehicle is in a driving state. In accordance with the magnitude of the hydraulic pressure adjusted by the hydraulic pressure adjustment mechanism 60 that adjusts the magnitude of the hydraulic pressure accordingly. That is, as shown in FIGS. 4 and 5, the moving body 51 has a cylindrical shape, is inserted into the housing 7 so as to be axially movable relative to the control valve 30, and the input shaft 2 is concentrically disposed in the center hole thereof. It is inserted so that it can move in the axial direction. The space between the outer periphery of the moving body 51 and the inner periphery of the housing 7 and the space between the inner periphery of the moving body 51 and the outer periphery of the input shaft 2 are sealed in an oil-tight manner via seal members 55 and 56, respectively. . Thereby, an oil chamber 52 is formed between the moving body 51 and the upper end of the housing 7. Further, a ball is provided between a plurality of axial grooves provided on the outer periphery of the input shaft 2 at circumferential intervals and a plurality of axial grooves provided on the inner periphery of the moving body 51 at circumferential intervals. The moving body 51 rotates together with the input shaft 2 by 53 being sandwiched. A compression return spring 54 is fitted to the input shaft 2 between the moving body 51 and the first valve member 31.

  The oil chamber 52 is connected to the pump 42 via a hydraulic adjustment mechanism 60. The hydraulic adjustment mechanism 60 adjusts the hydraulic pressure applied to the moving body 51 according to the driving state of the vehicle. As shown in FIG. 6, the hydraulic adjustment mechanism 60 is inserted into the holding hole 61 formed in the housing 7 so as not to rotate relative to the cylindrical sleeve 62, and inserted into the sleeve 62 so as to be rotatable relative to its own axis. The spool 63 is provided. 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 52 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. 7, 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. That is, the hydraulic pressure applied to the moving body 51 is increased by increasing the opening degree of the variable throttle 60a during high-speed traveling, so that the moving body 51 moves downward in the figure against the elasticity of the return spring 54. To increase. The hydraulic pressure applied to the moving body 51 is reduced by reducing the opening of the variable throttle 60a as the vehicle speed decreases, whereby the moving amount of the moving body 51 increases upward in the figure due to the elasticity of the return spring 54. .

  As shown in FIGS. 1, 4, and 5, an elastic member 70 is provided that generates an elastic force that restricts the relative rotation of the input / output shafts 2 and 3 according to the amount of relative rotation. The elastic member 70 of the present embodiment is disposed between the first valve member 31 and the moving body 51 in the housing 7 and has a cylindrical shape having an axis parallel to the axis of the input / output shafts 2 and 3. One end of the elastic member 70 is a fixed end fixed to the first valve member 31 by press fitting or the like, and the fixed end rotates along with the output shaft 3 at a position eccentric from the axis of the input / output shafts 2 and 3. The other end of the elastic member 70 is a free end separated from the fixed end in the axial direction of the input / output shafts 2 and 3. A part of the moving body 51 has a notch 51 a so as not to interfere with the elastic member 70.

  A rigidity adjusting mechanism 80 is provided that adjusts the rigidity of the elastic member 70 so that the elastic force generated by the elastic member 70 changes according to the amount of movement of the moving body 51. The rigidity adjusting mechanism 80 of the present embodiment includes a pressing portion 82 ′ that rotates together with the moving body 51 at a position deviated from the axis of the input / output shafts 2 and 3 and moves in the axial direction. That is, the pressing portion 82 ′ is configured by the inner periphery of the opening 82 a provided in the ring-shaped plate 82 attached to the lower end of the moving body 51. By inserting the elastic member 70 into the opening 82 a, the pressing portion 82 ′ is disposed at a position where the elastic member 70 is pressed along the relative rotation direction by the relative rotation of the input / output shafts 2 and 3. Due to the elastic bending deformation of the elastic member 70 caused by the pressing of the pressing portion 82 ′, an elastic force that restricts the relative rotation of the input / output shafts 2 and 3 is generated. And the pressing position of the elastic member 70 by the pressing part 82 'in the axial direction of the input / output shafts 2 and 3 is changed by the movement of the moving body 51 according to the operating state. The bending rigidity of the elastic member 70 changes according to the change in the pressing position. That is, since the moving body 51 moves downward as the vehicle speed increases, the distance from the fixed end of the elastic member 70 to the pressing position by the pressing portion 82 ′ is shortened, and the bending rigidity of the elastic member 70 is increased. Since the moving body 51 moves upward due to the decrease in the vehicle speed, the distance from the fixed end of the elastic member 70 to the pressing position by the pressing portion 82 ′ increases, and the bending rigidity of the elastic member 70 decreases.

  According to the first embodiment, the input / output shafts 2 and 3 are relatively rotated by the action of the steering torque, and the relative rotation of the input / output shafts 2 and 3 is restricted by the elastic force generated by the torsion bar 6 and the elastic member 70. . The bending rigidity of the elastic member 70 is adjusted by changing the pressing position of the elastic member 70 by the pressing portion 82 ′ by moving the moving body 51 by an amount corresponding to the driving state of the vehicle. Therefore, the relative rotation amounts of the input / output shafts 2 and 3 according to the steering torque change according to the driving state of the vehicle, and the hydraulic pressure for generating the steering assist force controlled by the hydraulic control valve 30 changes. That is, since the flexural rigidity of the elastic member 70 increases as the vehicle speed increases, the relative rotation amount of the input / output shafts 2 and 3 decreases, and the steering assist force decreases. Since the bending rigidity of the elastic member 70 is reduced due to the decrease in the vehicle speed, the relative rotation amount of the input / output shafts 2 and 3 is increased, and the steering assist force is increased.

  8 and 9 show a second embodiment of the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. Differences will be described.

  The moving body 151 of the moving mechanism 150 according to the second embodiment moves in the axial direction with respect to the input / output shafts 2 and 3 and is relatively arranged with an axial interval between the input / output shafts 2 and 3. It has the piece 151a and the 2nd moving body piece 151b. In addition, a cylindrical member 141 that is coaxially fixed to the upper portion of the first valve member 31 is inserted into the housing 7 so as to be relatively rotatable. As a result, the cylindrical member 141 rotates along with the output shaft 3 and moves relative to the input shaft 2. Relative rotation. Each of the movable body pieces 151a and 151b has a cylindrical shape, and is inserted into the cylindrical member 141 so as to be axially movable relative to the control valve 30, and the input shaft 2 is inserted into the center hole thereof so as to be axially relatively movable. Has been. Between the outer periphery of each moving body piece 151a, 151b and the inner periphery of the cylindrical member 141, and between the inner periphery of each moving body piece 151a, 151b and the outer periphery of the input shaft 2, it is sealed in an oil-tight manner, respectively. The As a result, a first oil chamber 152a is formed between the first moving body piece 151a and the upper end of the housing 7, and a second oil chamber 152b is formed between the second moving body piece 151b and the control valve 30. Yes.

  The rigidity adjusting mechanism 180 according to the second embodiment includes a displacement member 181 that is screwed to the input shaft 2 and connected to the output shaft 3 so as to be able to rotate along with the output shaft 3 and move in the axial direction between the movable body pieces 151a and 151b. Have. The displacement member 181 is screwed to the input shaft 2 via a ball screw having a ball 182 that circulates in a screw groove formed on the inner periphery of the displacement member 181 and the outer periphery of the input shaft 2. Balls 153 are provided between a plurality of axial grooves provided on the outer periphery of the displacement member 181 at circumferential intervals and a plurality of axial grooves provided on the inner periphery of the cylindrical member 141 at circumferential intervals. By being sandwiched, the displacement member 181 rotates along with the output shaft 3. Accordingly, the displacement member 181 is displaced in the axial direction with respect to the input / output shafts 2 and 3 by the relative rotation of the input / output shafts 2 and 3.

  The elastic member 170 according to the second embodiment includes a first spring piece 170a that is a compression coil spring disposed between the first moving body piece 151a and the displacement member 181, and a second moving body piece 151b and the displacement member 181. And a second spring piece 170b which is a compression coil spring disposed between the spring pieces 170a and 170b. Accordingly, the spring pieces 170 a and 170 b are elastically deformed along the axial direction of the input / output shafts 2 and 3 due to the displacement of the displacement member 181 due to the relative rotation of the input / output shafts 2 and 3. Due to this elastic deformation, elasticity that restricts the relative rotation of the input / output shafts 2 and 3 is generated according to the relative rotation amount of the input / output shafts 2 and 3.

  In the second embodiment, the pressure oil delivery port 62b of the hydraulic adjustment mechanism 60 communicates with the first oil chamber 152a and the second oil chamber 152b. When traveling at a high speed, the hydraulic pressure acting on both moving body pieces 151a and 151b increases, so that both moving body pieces 151a and 151b move in the direction toward each other against the elasticity of both spring pieces 170a and 170b. To increase. As the vehicle speed decreases, the hydraulic pressure acting on both moving body pieces 151a and 151b decreases, and as a result, the amount of movement of both moving body pieces 151a and 151b in the direction away from each other increases due to the elasticity of both spring pieces 170a and 170b. To do. That is, the first moving body piece 151a and the second moving body piece 151b move in opposite directions by an amount corresponding to the driving state of the vehicle. In the second embodiment, the return spring 54 of the first embodiment is not necessary.

  Each of the spring pieces 170a and 170b is a non-linear spring whose longitudinal elastic coefficient changes according to the amount of elastic deformation along the axial direction of the input / output shafts 2 and 3. Thereby, when both the moving body pieces 151a and 151b move according to the operating state, the spring pieces 170a and 170b are elastically deformed along the axial direction, so that the longitudinal elastic modulus changes. That is, when the moving body pieces 151a and 151b come close to each other due to an increase in the vehicle speed, the longitudinal elastic modulus of each of the spring pieces 170a and 170b increases. When the moving body pieces 151a and 151b are separated from each other due to a decrease in the vehicle speed, the longitudinal elastic modulus of each of the spring pieces 170a and 170b becomes small. Others are the same as in the first embodiment.

  According to the second embodiment, the input / output shafts 2 and 3 are rotated relative to each other by the action of the steering torque, and the relative rotation of the input / output shafts 2 and 3 is caused by the elasticity generated by the torsion bar 6 and the two spring pieces 170a and 170b. Be regulated. The longitudinal elastic modulus of the two spring pieces 170a and 170b is adjusted by changing the amount of elastic deformation of the two spring pieces 170a and 170b by the movement of the two moving body pieces 151a and 151b in an amount corresponding to the driving state of the vehicle. . Therefore, the relative rotation amounts of the input / output shafts 2 and 3 according to the steering torque change according to the driving state of the vehicle, and the hydraulic pressure for generating the steering assist force controlled by the hydraulic control valve 30 changes. That is, since the rigidity of both the spring pieces 170a and 170b increases as the vehicle speed increases, the relative rotation amount of the input / output shafts 2 and 3 decreases, and the steering assist force decreases. Since the rigidity of both spring pieces 170a and 170b is reduced due to the reduction in the vehicle speed, the relative rotation amount of the input / output shafts 2 and 3 is increased, and the steering assist force is increased.

  FIGS. 10 and 11 show a third embodiment of the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals, the description thereof will be omitted, and different points will be described.

  The moving body 251 of the moving mechanism 250 in the third embodiment is connected to the input shaft 2 so as to move in the axial direction with respect to the input / output shafts 2 and 3, and rotate relative to the output shaft 3. That is, the movable body 251 has a cylindrical shape, is inserted into the housing 7 so as to be axially movable relative to the control valve 30, and the input shaft 2 is inserted into the center hole thereof so as to be axially relatively movable. . The space between the outer periphery of the moving body 251 and the inner periphery of the housing 7 and the space between the inner periphery of the moving body 251 and the outer periphery of the input shaft 2 are sealed in an oil-tight manner by seal members 55 and 56, respectively. Thereby, an oil chamber 252 is formed between the moving body 251 and the upper end of the housing 7. Further, similarly to the first embodiment, a plurality of axial grooves provided on the outer periphery of the input shaft 2 at circumferential intervals, and a plurality of grooves provided on the inner periphery of the moving body 251 at circumferential intervals. When the ball 53 is sandwiched between the axial grooves, the moving body 251 rotates along with the input shaft 2.

  The rigidity adjusting mechanism 280 according to the third embodiment includes a receiving portion 281 that rotates along with the output shaft 3 and is disposed at a distance from the moving body 251 in the axial direction of the input shaft 2. The receiving portion 281 of this embodiment is configured by the upper end portion of the first valve member 31.

  The elastic member 270 of the third embodiment has one end 270a connected to the moving body 251 so as to rotate together and the other end 270b connected so as to rotate accompanying the receiving portion 281. It is compressed between the body 251 and the receiving part 281. The elastic member 270 of this embodiment has a truncated cone shape with a central hole, and is a rubber whose torsional rigidity changes according to the amount of compression in the axial direction of the input / output shafts 2 and 3. One end portion 270a of the elastic member 270 is connected to the lower surface of the moving body 251, and the other end portion 270b is connected to the receiving portion 281 so as to rotate together with, for example, an uneven fitting portion or an adhesive. As a result, the elastic force that restricts the relative rotation of the input / output shafts 2 and 3 due to the elastic torsional deformation of the elastic member 270 due to the relative rotation of the input / output shafts 2 and 3 causes the relative rotation amount of the input / output shafts 2 and 3 In response.

  A pressure oil delivery port 62 b of the hydraulic adjustment mechanism 60 leads to the oil chamber 252. When traveling at high speed, the hydraulic pressure acting on the moving body 251 increases. Thereby, the moving body 251 increases the amount of movement downward in the figure against the elasticity of the elastic member 270. The hydraulic pressure acting on the moving body 251 decreases as the vehicle speed decreases. As a result, the moving amount of the moving body 251 increases upward in the figure due to the elasticity of the elastic member 270. In the third embodiment, the return spring 54 of the first embodiment is not necessary.

  When the moving body 251 moves according to the operating state, the amount of compression of the elastic member 270 in the axial direction of the input / output shafts 2 and 3 between the moving body 251 and the receiving portion 281 changes, and the elasticity changes according to the change. The torsional rigidity of the member 270 changes. That is, since the moving body 251 moves downward as the vehicle speed increases, the compression amount of the elastic member 270 increases and the torsional rigidity increases. Since the moving body 251 moves upward due to the decrease in the vehicle speed, the elastic member 270 has a reduced compression amount and a reduced torsional rigidity. Others are the same as in the first embodiment.

  The elastic member 270 may be a torsion coil spring that is fitted to the input shaft 2 and has a torsional rigidity that changes in accordance with a change in the compression amount in the axial direction of the input / output shafts 2 and 3.

  According to the third embodiment, the input / output shafts 2 and 3 are relatively rotated by the action of the steering torque, and the relative rotation of the input / output shafts 2 and 3 is restricted by the elastic force generated by the torsion bar 6 and the elastic member 270. . The torsional rigidity of the elastic member 270 is adjusted by changing the amount of compression of the elastic member 270 by the movement of the moving body 251 according to the driving state of the vehicle. Therefore, the relative rotation amounts of the input / output shafts 2 and 3 according to the steering torque change according to the driving state of the vehicle, and the hydraulic pressure for generating the steering assist force controlled by the hydraulic control valve 30 changes. That is, since the torsional rigidity of the elastic member 270 increases as the vehicle speed increases, the relative rotation amount of the input / output shafts 2 and 3 decreases, and the steering assist force decreases. As the vehicle speed decreases, the torsional rigidity of the elastic member 270 decreases, so that the relative rotation amount of the input / output shafts 2 and 3 increases and the steering assist force increases. In addition, since the relative rotation of the input / output shafts 2 and 3 can be directly converted into the torsional deformation of the elastic member 270, the structure can be simplified.

FIG. 12 shows a fourth embodiment of the present invention. The same parts as those of the third embodiment are denoted by the same reference numerals, and the description thereof will be omitted. Differences will be described.
In the fourth embodiment, a blocking portion 390 that prevents deformation of the elastic member 270 in the radial direction of the input / output shafts 2 and 3 is provided. The blocking portion 390 of the present embodiment surrounds the upper outer periphery of the elastic member 270 and has an annular shape in cross section. The outer peripheral surface is along a cylindrical surface, and the inner peripheral surface is an outer peripheral conical surface of the elastic member 270. The upper end is integrated with the lower end surface of the moving body 251. As a result, it is possible to prevent a change in torsional rigidity according to a change in the axial compression amount of the elastic member 270 from being suppressed by radial deformation, and to expand the material selection range of the elastic member 270 to increase the degree of design freedom, In addition, the running stability can be improved by increasing the rigidity during high-speed straight running. Others are the same as in the third embodiment.

FIGS. 13 and 14 show a fifth embodiment of the present invention. The same parts as those of the third embodiment are denoted by the same reference numerals, description thereof is omitted, and differences will be described.
In the fifth embodiment, a blocking portion 490 that prevents deformation of the elastic member 270 in the radial direction of the input / output shafts 2 and 3 is provided. The blocking portion 490 of the present embodiment is configured by a plurality (four in the illustrated example) of blocking pieces 490a arranged so as to surround the upper outer periphery of the elastic member 270, and each blocking piece 490a is in the circumferential direction of the elastic member 270. In the arrangement state, the outer peripheral surface is along the cylindrical surface, and the inner peripheral surface is along the outer peripheral conical surface of the elastic member 270. In addition, circumferential grooves 490a ′ are formed on the outer periphery of each blocking piece 490a, and the band 491 is fitted into these circumferential grooves 490a ′, thereby preventing the blocking pieces 490a from being dispersed during assembly. Further, instead of the seal between the outer periphery of the moving body 251 and the inner periphery of the housing 7, the outer periphery of the blocking portion 490 and the inner periphery of the housing 7 are sealed in an oil-tight manner by the seal member 55. As a result, the pressure oil in the oil chamber 252 passes through the gap between the outer periphery of the movable body 251 and the inner periphery of the housing 7, and reaches between the outer periphery of each blocking piece 490 a and the inner periphery of the housing 7. Therefore, the elastic member 270 can be pressed along the radial direction by the blocking pieces 490a by hydraulic pressure, and deformation of the elastic member 270 in the radial direction of the input / output shafts 2 and 3 can be effectively blocked. Others are the same as in the fourth embodiment.

  The present invention is not limited to the above embodiment. For example, the input shaft and the output shaft may be connected via only an elastic member without using a torsion bar. The driving state of the vehicle is not limited to the vehicle speed. For example, the hydraulic pressure may be adjusted by a hydraulic pressure adjustment mechanism in accordance with the steering angle. Further, the moving member may be moved by an electric actuator that moves according to the driving state of the vehicle without using the hydraulic pressure adjusting mechanism. In the first embodiment, the moving body may rotate along with the output shaft, and the elastic member may rotate along with the input shaft. In the second embodiment, the displacement member may be screwed onto the output shaft and connected to the input shaft so as to rotate along with the input shaft and move relative to the axial direction. In the third to fifth embodiments, the moving body may rotate along with the output shaft, and the receiving portion may rotate along with the input shaft. The present invention can be applied to hydraulic power steering devices other than the rack and pinion type. For example, the present invention may be applied to a ball screw type hydraulic power steering device in which an output shaft is integrated with a ball screw shaft.

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. Sectional drawing of the hydraulic adjustment mechanism in the hydraulic power steering apparatus of embodiment of this invention Action explanatory drawing of the hydraulic adjustment mechanism in the hydraulic power steering device of the embodiment of the present invention The longitudinal section of the important section in the hydraulic power steering device of a 2nd embodiment of the present invention. IX-IX sectional view of FIG. The longitudinal cross-sectional view of the principal part in the hydraulic power steering device of 3rd Embodiment of this invention XI-XI line sectional view of FIG. The longitudinal cross-sectional view of the principal part in the hydraulic power steering device of 4th Embodiment of this invention The longitudinal section of the important section in the hydraulic power steering device of a 5th embodiment of the present invention. XIV-XIV line sectional view of FIG.

Explanation of symbols

2 Input shaft 3 Output shaft 20 Hydraulic cylinder (hydraulic actuator)
30 Hydraulic control valve 50, 150, 250 Moving mechanism 51, 151, 251 Moving body 70, 170, 270 Elastic member 80, 180, 280 Rigidity adjusting mechanism 82 'Pressing portion 151a First moving body piece 151b Second moving body piece 170a First spring piece 170b Second spring piece 181 Displacement member 270a One end 270b Other end 281 Receiving portion 390 Blocking portion

Claims (5)

An input shaft;
An output shaft coupled to the input shaft in an elastically rotatable manner according to a steering torque;
A hydraulic actuator for generating steering assist force;
A hydraulic 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 moving mechanism having a moving body that moves by an amount according to the driving state of the vehicle;
An elastic member that generates an elastic force that restricts relative rotation of the input / output shaft according to the amount of relative rotation;
A hydraulic power steering apparatus comprising: a stiffness adjusting mechanism that adjusts the stiffness of the elastic member so that the elasticity changes according to the amount of movement of the movable body. The moving body is connected so as to move in the axial direction with respect to the input / output shaft and rotate along with one of the input / output shafts,
The elastic member has a fixed end that rotates together with the other of the input / output shafts at a position eccentric from the axis of the input / output shaft, and a free end separated from the fixed end in the axial direction of the input / output shaft. ,
The rigidity adjusting mechanism has a pressing portion that rotates along with the moving body and moves along the axial direction.
The pressing portion is disposed at a position where the elastic member is pressed by relative rotation of the input / output shaft.
The elasticity is generated by elastic bending deformation of the elastic member by pressing of the pressing portion,
2. The hydraulic power steering apparatus according to claim 1, wherein a bending rigidity of the elastic member changes according to a change in a pressing position by the pressing portion in an axial direction of the input / output shaft. The moving body has a first moving body piece and a second moving body piece that move in the axial direction with respect to the input / output shaft and are relatively disposed with an interval in the axial direction of the input / output shaft.
The first moving body piece and the second moving body piece move in opposite directions by an amount corresponding to the driving state of the vehicle,
The rigidity adjusting mechanism includes a displacement member that is screwed to one of the input shaft and the output shaft between the two moving body pieces, and is connected to the other so as to be able to rotate together and move in the axial direction. And
The elastic member includes a first spring piece disposed between the first moving body piece and the displacement member, and a second spring piece disposed between the second moving body piece and the displacement member. Have
The displacement member is axially displaced with respect to the input / output shaft by relative rotation of the input / output shaft,
The elasticity is generated by elastic deformation along the axial direction of the input / output shaft of each spring piece due to the displacement of the displacement member,
2. The hydraulic power steering apparatus according to claim 1, wherein each of the spring pieces is a non-linear spring whose longitudinal elastic coefficient changes in accordance with an elastic deformation amount along an axial direction of the input / output shaft. The moving body is connected so as to move in the axial direction with respect to the input / output shaft and rotate along with one of the input / output shafts,
The rigidity adjusting mechanism has a receiving portion that rotates along with the other of the input / output shafts and is disposed at an interval in the axial direction of the input / output shaft from the moving body,
The elastic member has one end connected to the moving body to rotate along with the moving body and the other end connected to rotate along with the receiving section, and the moving body and the receiving section Compressed between
The elasticity is generated by elastic torsional deformation of the elastic member due to relative rotation of the input / output shaft,
2. The hydraulic power steering apparatus according to claim 1, wherein the torsional rigidity of the elastic member changes in accordance with a change in compression amount in the axial direction of the input / output shaft between the moving body and the receiving portion. The hydraulic power steering device according to claim 4, further comprising a blocking portion that blocks deformation of the elastic member in a radial direction of the input / output shaft.

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