JP2007008391A - Seal structure, and power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a seal structure capable of reducing sliding/rotating resistance at a part where one side surface of a seal ring contacts with a side surface of an annular groove, and a power steering device capable of decreasing steering force required when a steering wheel connected to a valve body is steered and obtaining good steering feeling. <P>SOLUTION: A cylindrical valve body 5 and a valve spool fitted so as to displace a relative angle by steering the steering wheel; a valve housing 7 wherein the valve body 5 is internally fitted in a pressure liquid chamber 71 so as to rotate; and the seal ring 8 fitted with the annular groove 4 provided on the valve body 5, and pressed in a diametrical direction and to a first side in an axial length direction by pressure liquid of the pressure liquid chamber 71 to prevent the leakage of the pressure liquid are equipped. A pressure receiving recessed portion 81 wherein the pressure liquid in the annular groove 4 presses the seal ring 8 to a second side in the axial length direction is provided on one side surface 8a of the seal ring 8. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention includes a seal structure that prevents leakage of pressurized liquid between the first member and the second member, and a rotary hydraulic pressure control valve that performs a hydraulic pressure control operation using a relative angular displacement between the valve body and the valve spool. The present invention relates to a power steering device.

  A power steering device including a hydraulic pressure control valve includes an input shaft connected to a steering wheel and capable of rotating, an output shaft coaxially connected to the input shaft by a torsion bar, and a steering mechanism of the vehicle. A hydraulic pressure control valve that is connected to a hydraulic cylinder for assisting steering and a hydraulic pump, and that supplies and discharges hydraulic fluid in response to steering of the steering wheel, and the output shaft is a rack and pinion type It is comprised so that it may connect with the steering apparatus of (for example, refer patent document 1).

  Further, the hydraulic pressure control valve of Patent Document 1 includes a cylindrical valve body connected to the output shaft, a valve spool fitted to the valve body so as to be capable of relative angular displacement, and connected to the input shaft, A cylindrical valve housing having a pressure fluid chamber in which the valve body is accommodated and having a supply / discharge port, and a plurality of annular grooves provided on an outer peripheral surface of the valve body and the pressure fluid And a plurality of seal rings which are pressed by the chamber pressure fluid outward in the radial direction and in one axial direction to prevent leakage of the fluid pressure.

  The seal ring prevents pressure fluid supplied and discharged through the port of the valve housing from leaking from the gap between the inner peripheral surface of the valve housing and the outer peripheral surface of the valve body, and is parallel to both side surfaces of the annular groove. The cross section has a rectangular shape with two side surfaces having the same pressure receiving area, and is formed of a flexible material. Then, when the pressure fluid in the pressure fluid chamber enters the annular groove from the gap, the seal ring is pressed to one side in the axial direction and radially outward, and one side surface of the seal ring is one side surface of the annular groove. The outer peripheral surface of the seal ring comes into full contact with the inner peripheral surface of the valve housing.

As described above, in the power steering device having the seal ring, when the steering assist force by the hydraulic cylinder becomes large, such as when the vehicle turns, the throttle amount between the valve body and the valve spool increases, and the pressure The liquid pressure in the liquid chamber and the liquid pressure in the annular groove will increase, and the force for pressing the seal ring will be relatively large. The seal structure includes the annular groove and the seal ring.
JP 2003-312501 A

  By the way, the conventional power steering device and the seal ring of the seal structure disclosed in Patent Document 1 and the like are configured to be pressed in one axial direction and radially outward by the pressure liquid in the annular groove, so that the vehicle turns. When the fluid pressure in the pressure fluid chamber and the fluid pressure in the annular groove rise, the seal ring is fixed to the inner peripheral surface of the valve housing as a stationary member. Sliding occurs between one side surface and the side surface of the annular groove, and the valve body slides and rotates with respect to the seal ring and the valve housing. Therefore, the sliding rotation resistance of the valve body is relatively large, and steering means connected to the valve body is provided. Steering force required for steering is increased, and there has been a demand for an improvement in steering feeling.

  The present invention has been made in view of such circumstances, and a main object thereof is a seal structure and a valve body as a second member that can reduce sliding rotation resistance at a location where one side surface of the seal ring contacts the side surface of the annular groove. An object of the present invention is to provide a power steering device that can reduce the steering force required when the steering means connected to the vehicle is steered and can obtain a good steering feeling.

  A seal structure according to a first aspect of the present invention includes an annular groove provided on one of a first member having a pressurized fluid chamber and a second member fitted to the pressurized fluid chamber so as to be capable of relative rotation, and fitted in the annular groove. And a seal ring that is pressed by the pressure fluid in the pressure fluid chamber in one of the radial direction and the axial length direction thereof to prevent leakage of the pressure fluid, and the side surface of the annular groove and the seal ring At least one of the side surfaces has a pressure receiving recess that the pressure liquid presses the seal ring to the other in the axial direction.

  The seal structure according to a second aspect of the invention is characterized in that the annular groove is provided on the outer peripheral surface of the second member, and the pressure receiving recess is provided on one side surface of the seal ring and in the middle in the radial direction. .

  According to a third aspect of the present invention, there is provided a power steering device having a cylindrical valve body and a valve spool fitted so as to be capable of relative angular displacement by steering of a steering means, a pressure fluid chamber, and the valve body in the pressure fluid chamber. A valve housing fitted in a rotatable manner, and fitted in an annular groove provided in one of the valve housing and the valve body, and in the radial direction and the axial length direction thereof by the pressure liquid in the pressure liquid chamber A power ring device that includes a seal ring that is pressed to prevent leakage of the pressure fluid, and that assists steering by the pressure fluid that increases pressure based on the relative angular displacement, and at least one of a side surface of the annular groove and a side surface of the seal ring Is characterized in that the pressure liquid has a pressure receiving recess for pressing the seal ring in the other axial direction in a part of the radial direction.

  In a power steering device according to a fourth aspect of the invention, the annular groove is provided on an outer peripheral surface of the valve body, and the pressure receiving recess is provided on one side surface of the seal ring and in the middle in the radial direction. .

  In the first invention, the seal ring is pressed in one of the radial direction and the axial length direction by the pressure liquid in the annular groove, and the peripheral surface of the seal ring is pressed against the peripheral surface of the first member. One side is pressed against one side of the annular groove. However, a pressure receiving recess is provided on one of the side surface of the seal ring and the side surface of the annular groove, and the seal ring can be pressed to the other in the axial direction by the pressure liquid applied to the pressure receiving recess. The difference between the pressing force pressed to one side in the axial direction and the pressing force pressed to the other side in the axial direction can be reduced, and the location where one side surface of the seal ring contacts the side surface of the annular groove can be reduced. Sliding rotation resistance can be reduced. In addition, the contact area where the one side surface of the seal ring contacts the side surface of the annular groove can be reduced by the pressure receiving recess, and the sliding rotation resistance can be further reduced. Further, since the sliding rotation resistance can be reduced, the pressure liquid in the annular groove can be infiltrated and wetted between one side surface of the seal ring and the side surface of the annular groove. Can be reduced. Therefore, the rotability of the second member can be increased, and the force required to rotate the second member can be reduced.

  In the second and fourth inventions, the pressure receiving recesses are provided on one side of the seal ring and in the middle of the radial direction, and the surfaces on both sides in the radial direction of the pressure receiving recess are brought into contact with one side of the annular groove. Therefore, the pressure receiving recess can be provided by molding the seal ring, and the cost can be reduced instead of having the pressure receiving recess, and the stability in the annular groove of the seal ring can be increased.

  In the third invention, the seal ring is pressed in one of the radial direction and the axial length direction by the pressure liquid in the annular groove, the peripheral surface of the seal ring is pressed against the peripheral surface of the valve housing, and The side surface is pressed against one side surface of the annular groove. However, a pressure receiving recess is provided on one of the side surface of the seal ring and the side surface of the annular groove, and the seal ring can be pressed to the other in the axial direction by the pressure liquid applied to the pressure receiving recess. The difference between the pressing force pressed to one side in the axial direction and the pressing force pressed to the other side in the axial direction can be reduced, and the location where one side surface of the seal ring contacts the side surface of the annular groove can be reduced. Sliding rotation resistance can be reduced. In addition, the contact area where the one side surface of the seal ring contacts the side surface of the annular groove can be reduced by the pressure receiving recess, and the sliding resistance can be further reduced. Further, since the sliding rotation resistance can be reduced, the pressure liquid in the annular groove can be infiltrated and wetted between one side surface of the seal ring and the side surface of the annular groove. Can be reduced. Therefore, the steering force required when the steering means connected to the valve body is steered can be reduced, and a good steering feeling can be obtained.

  Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof. 1 is a cross-sectional view showing a configuration of a part of a power steering apparatus having a seal structure according to the present invention, FIG. 2 is a schematic longitudinal plan view of a main part, FIG. 3 is an enlarged cross-sectional view of the main part, and FIG. FIG. 5 is a schematic view of the entire power steering apparatus.

  A power steering device having a seal structure includes an input shaft 1 connected to a steering wheel A as a steering means and capable of rotating, an output shaft 3 coaxially connected to the input shaft 1 by a torsion bar 2, A tubular valve body 5 connected to the input shaft 1 and having four annular grooves 4 on the outer peripheral surface, and a valve spool 6 fitted to the valve body 5 so as to be capable of relative angular displacement and connected to the input shaft 1. And a valve housing 7 having a pressure fluid chamber 71 in which the valve body 5 is rotatably fitted, and a pressure fluid fitted in each annular groove 4 and supplied to the pressure fluid chamber 71 in the radial direction and There are four seal rings 8 that are pressed in the axial direction to prevent leakage of the pressurized liquid. The valve housing 7 constitutes a first member, and the valve body 5 constitutes a second member.

  The input shaft 1 has a cylindrical portion 1a on the side where the torsion bar 2 is connected, and a cylindrical valve spool 6 is integrally provided at the tip of the cylindrical portion 1a. A torsion bar 2 is inserted into the valve spool 6 and the cylinder part 1a, and one end of the torsion bar 2 is connected to the base end of the cylinder part 1a by a dowel pin 9. Further, the tip of the cylindrical portion 1 a is rotatably supported by one end portion of the output shaft 3 by a needle bearing 10.

  The output shaft 3 has a fitting hole 3a at one end and a pinion 11 that meshes with a rack tooth of a rack shaft, which will be described later, at the other end, and the other end of the torsion bar 2 and the needle in the fitting hole 3a. Each bearing 10 is fitted inside. The torsion bar 2 is connected by spline fitting.

  The valve body 5 has a cylindrical shape integrally connected to one end of the output shaft 3 by a connecting pin 12, and can be displaced relative to the valve spool 6 within the range of torsion of the torsion bar 2. . The amount of the relative angular displacement is about 5 ° at the maximum, and the valve body 5 and the valve spool 6 rotate integrally when the amount is greater than the maximum relative angular displacement amount, that is, beyond the torsional range of the torsion bar 2.

  Inside the valve body 5, a plurality of first liquid grooves 5 a each having an equal width are arranged in parallel in the circumferential direction, and each of the outer circumferences of the valve spool 6 is similarly arranged. A plurality of second liquid grooves 6a having equal widths are arranged in parallel in the circumferential direction.

  The first and second liquid grooves 5a, 6a are staggered in the circumferential direction in a neutral state where the torsion bar 2 is not twisted, and each of the first liquid grooves 5a is between the second liquid grooves 6a. Each of the second liquid grooves 6a is opposed to the land between the first liquid grooves 5a, and the first liquid groove 5a is disposed on the fitting periphery of the valve body 5 and the valve spool 6. The liquid chambers on the inner side and the liquid chambers on the outer side of the second liquid groove 6a are alternately arranged, and the communication portion between the liquid chambers, that is, the width of the first and second liquid grooves 5a and 6a. The groove edges on both sides in the direction act as throttle portions 5b and 6b that increase or decrease the respective communication areas (throttle areas) according to the relative angular displacement.

  Further, the valve body 5 has a liquid supply hole 5c that communicates with the discharge side of the hydraulic pump P that is a hydraulic pressure source, a first liquid supply hole 5d that communicates with one cylinder chamber of the hydraulic cylinder S, and a hydraulic pressure. A second liquid feed hole 5e communicating with the other cylinder chamber of the cylinder S and four annular grooves 4 are provided. As shown in FIG. 1, the liquid supply hole 5c and the first and second liquid supply holes 5d and 5e are separated from each other in the axial length direction, and the liquid supply hole is provided between the first and second liquid supply holes 5d and 5e. The hole 5c is arranged. Two annular grooves 4 are provided on the outer peripheral surface between the liquid supply hole 5c and the first and second liquid supply holes 5d and 5e, and the first and second liquid supply holes 5d and 5e One annular groove 4 is provided on the outer peripheral surface opposite to the liquid supply hole 5c. The annular groove 4 has two side surfaces 4a and 4b that are spaced apart and parallel to each other, and a peripheral surface 4c that is continuous with the side surfaces 4a and 4b. The valve spool 6 has a drain hole 6c that communicates with a liquid tank T serving as a drain destination.

  The valve housing 7 has ports 7a, 7b, 7c, 7d that open to the pressure chamber 71 at positions corresponding to the liquid supply holes 5c, the first and second liquid supply holes 5d, 5e, and the drain holes 6c. Each port 7a, 7b, 7c, 7d is connected to a hydraulic pump P, a hydraulic cylinder S, and a hydraulic tank T by liquid pipes 13-16.

  The seal ring 8 allows the pressure liquid supplied to the liquid supply hole 5 c and the pressure liquid supplied from the first and second liquid supply holes 5 d and 5 e to pass through the inner peripheral surface of the valve housing 7 and the valve body 5. In order to prevent leakage from the gap K between the outer peripheral surfaces, the two side surfaces 8a and 8b that face the two side surfaces 4a and 4b of the annular groove 4 in parallel and have the same pressure receiving area, and the peripheral surface 4c of the annular groove 4 It has a rectangular cross section having an inner peripheral surface having a larger diameter and an outer peripheral surface corresponding to the inner peripheral surface of the valve housing 7, and is formed of a flexible material.

  An annular pressure receiving recess 81 is provided in one side surface 8a of the seal ring 8 and in the radial central portion so that the pressure liquid in the annular groove 4 presses the seal ring 8 to the other in the axial direction. The pressure receiving recess 81 is formed of an annular groove having a width of about 2/3 of the radial thickness of the seal ring 8 and an equal depth over the entire width. The seal ring 8 is moved to the other side in the axial length direction in the pressure receiving recess 81. A pressing pressure is applied. Further, the surface roughness of the one side surface 8 a and the inner peripheral side from the pressure receiving recess 81 is such that the pressure liquid in the annular groove 4 can enter the pressure receiving recess 81.

  In the power steering apparatus configured as described above, the torsion bar 2 is twisted via the input shaft 1 when the steered wheel A as the steering means is operated from the steering neutral position, and the valve body 5 and A relative angular displacement occurs in the valve spool 6, and the pressure fluid supplied from the fluid pressure pump P to the first fluid groove 5a through the fluid pipe 13, the port 7a and the fluid supply hole 5c is controlled in flow rate by the throttle portion 5b or 6b. Then, pressurized liquid is supplied from one liquid feed hole 5d or 5e to one cylinder chamber of the hydraulic cylinder S, and the rack shaft R connected to one end of the piston of the hydraulic cylinder S moves in the axial direction. A pair of wheels connected to the rack shaft R and the other end of the piston are turned to provide steering assistance. During this steering assist, the output shaft 3 having the pinion 11 that meshes with the rack teeth of the rack shaft R rotates in conjunction with the movement of the rack shaft R in the axial length direction, and the valve connected to the output shaft 3. The body 5 rotates relative to the valve housing 7. Further, the pressurized liquid supplied to the first liquid groove 5 a flows into the annular groove 4 from the gap K between the inner peripheral surface of the valve housing 7 and the outer peripheral surface of the valve body 5, and the pressurized liquid in the annular groove 4 As a result, the seal ring 8 is pressed.

  When the steering assist is performed, the pressure of the pressurized liquid in the first liquid groove 5a and the annular groove 4 rises to a relatively high pressure, and the seal ring 8 moves from the gap K to the annular groove as shown in FIG. 4 is applied to the other side surface 8b in the axial length direction, and the pressure fluid pressure is applied radially outward to the inner peripheral surface of the seal ring 8, and the pressure fluid pressure is applied to the pressure receiving recess 81. Join. Accordingly, the seal ring 8 is relatively strongly pressed against the inner peripheral surface of the valve housing 7 by the pressure of the pressurized liquid applied to the inner peripheral surface, and the seal ring 8 is fixed to the valve housing 7. Further, the pressure ring P1 presses the seal ring 8 in one axial direction by the pressure liquid applied to the other side surface 8b of the seal ring 8, and the pressure ring applied to the pressure receiving recess 81 of the seal ring 8 causes the seal ring 8 to move in the other axial direction. The difference from the pressing force P2 that presses toward can be made relatively small. For this reason, the sliding rotation resistance of the location where one side surface 8a of the seal ring 8 contacts the side surface 4a of the annular groove 4 can be made relatively small.

  FIG. 6 is a graph showing the relationship between the sliding rotation resistance (torque) and the hydraulic pressure in the annular groove 4. The broken line in the figure indicates the characteristic when the pressure receiving recess 81 is not provided, and the solid line also indicates the characteristic when the pressure receiving recess 81 is provided. When the pressure receiving recess 81 is provided, the pressure receiving recess 81 is not provided. In comparison, the sliding rotation resistance (torque) can be reduced to about ½. Therefore, the steering force required when the steering means (steering wheel A) connected to the valve body 5 is steered can be reduced, and a good steering feeling can be obtained.

  FIG. 7 is a graph showing the relationship between the steering torque applied to the steering means and the hydraulic pressure generated by the hydraulic cylinder. The broken line in the figure shows the characteristic when the steering assist is not performed, and the alternate long and short dash line indicates the characteristic when the steering assist is performed by the steering assist force generated by the hydraulic cylinder S without the pressure receiving recess 81. Similarly, the solid line has a pressure receiving recess 81, and shows characteristics when the steering assist is performed by the steering assist force generated by the hydraulic cylinder. When the pressure receiving recess 81 is provided, the solid line pressure receiving recess 81 is shown. Steering torque can be reduced as compared with the case where there is no engine. Therefore, a good steering feeling can be obtained.

  In the embodiment described above, the valve spool 6 is connected to the input shaft 1 and the valve body 5 is connected to the output shaft 3. However, the valve spool 6 is connected to the output shaft 3. The valve body 5 may be connected to the input shaft 1.

  Further, in the embodiment described above, the annular groove 4 is provided on the outer peripheral surface of the valve body 5, but the annular groove 4 may be provided on the inner peripheral surface of the pressurized fluid chamber 71 of the valve housing 7.

  Further, although the pressure receiving recess 81 of the seal ring 8 is annular, the pressure receiving recess 81 may be configured to have an arc shape over substantially the entire circumference, or as a configuration having a plurality of circumferential positions. Also good. In this latter case, the plurality of pressure receiving recesses 81 may be arcuate, round, square, etc., and the configuration of the pressure receiving recesses 81 is not particularly limited. The plurality of pressure receiving recesses 81 may be configured to communicate with each other through a communication path.

  Further, the seal ring 8 has a surface roughness on one side surface 8a and on the inner peripheral side from the pressure receiving recess 81, so that the pressure liquid in the annular groove 4 can enter the pressure receiving recess 81. It is good also as a structure which has a pressurized liquid introduction path connected to the internal peripheral surface of the seal ring 8 and the pressure receiving recessed part 81.

  In addition, the seal structure according to the present invention is used in the power steering apparatus. In addition, the radial groove and the axial length direction of the annular groove 4 are fitted in the annular groove 4 and are pressurized by the pressure chamber 71. It can be used for an apparatus provided with a seal ring 8 that is pressed to prevent the pressure liquid from leaking.

It is sectional drawing which shows the structure of a part of power steering apparatus provided with the seal structure which concerns on this invention. It is a typical longitudinal section top view of the important section of a power steering device provided with the seal structure concerning the present invention. It is an expanded sectional view of the important section of a power steering device provided with the seal structure concerning the present invention. It is sectional drawing of the state in which the seal ring of a power steering apparatus provided with the seal structure which concerns on this invention is pressed. It is a schematic diagram of the whole power steering apparatus provided with the seal structure which concerns on this invention. It is a graph which shows the relationship between sliding rotation resistance (torque) and the hydraulic fluid force in an annular groove. It is a graph which shows the relationship between the steering torque added to a steering means, and the hydraulic pressure which a hydraulic cylinder generate | occur | produces.

Explanation of symbols

4 annular groove 4a side surface 5 valve body (second member)
6 Valve spool 7 Valve housing (first member)
Reference Signs List 71 Pressure chamber 8 Seal ring 8a One side 81 Pressure receiving recess A Steering wheel (steering means)

Claims (4)

  An annular groove provided on one of a first member having a pressurized fluid chamber and a second member fitted to the pressurized fluid chamber so as to be capable of relative rotation, and a pressure of the pressurized fluid chamber fitted in the annular groove. A seal structure that is pressed by the liquid in one of its radial direction and its axial length direction to prevent leakage of the pressurized liquid, and at least one of the side surface of the annular groove and the side surface of the seal ring is the pressurized liquid Has a pressure receiving recess for pressing the seal ring in the other axial direction.   The seal structure according to claim 1, wherein the annular groove is provided on an outer peripheral surface of the second member, and the pressure-receiving recess is provided on one side surface of the seal ring and in the middle of the radial direction.   A tubular valve body and a valve spool which are fitted so as to be capable of relative angular displacement by steering of the steering means, and a valve housing which has a pressure fluid chamber and in which the valve body is rotatably fitted. And is fitted into an annular groove provided in one of the valve housing and the valve body and is pressed in the radial direction and in the axial direction thereof by the pressurized liquid in the pressurized fluid chamber to prevent leakage of the pressurized fluid. A power steering device that assists steering with a pressurized liquid that is boosted based on the relative angular displacement, wherein at least one of a side surface of the annular groove and a side surface of the seal ring has the pressure liquid passing through the seal ring. A power steering device having a pressure receiving recess for pressing toward the other in the axial direction in a part in a radial direction. 4. The power steering apparatus according to claim 3, wherein the annular groove is provided on an outer peripheral surface of the valve body, and the pressure receiving recess is provided on one side surface of the seal ring and in the middle in the radial direction.

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