JP5124426B2 - Control valve for hydraulic power steering - Google Patents

Description

  The present invention relates to an improvement in a control valve for hydraulic power steering that is used in, for example, a hydraulic power steering device applied to a vehicle and controls the amount of hydraulic oil supplied to a so-called power cylinder of the hydraulic power steering device.

  As a conventional hydraulic power steering control valve, for example, a hydraulic power steering control valve applied to a rack and pinion steering device described in Patent Document 1 below is known.

  Briefly, this control valve is housed in a housing with one end open, and one end is rotatable relative to the input shaft via a torsion bar. The hydraulic oil supplied from an external hydraulic source is selected for each pressure chamber of the power cylinder according to the torsion amount of the torsion bar based on the relative rotation with the output shaft connected to the steered wheel at the other end. To supply.

  A cover member for closing the opening is provided at one end opening of the housing, and a ball bearing for rotatably supporting the input shaft is accommodated and held on the inner peripheral side of the cover member. ing. The cover member is fixed to the opening end surface of the housing with a plurality of bolts.

In this way, in the control valve, by adopting a configuration in which the input shaft is supported by the housing via the cover member and the ball bearing, the support stability of the input shaft can be improved, and input due to vehicle vibration can be achieved. Even when a radial load is applied to the shaft, it is possible to suppress the radial deformation of the input shaft.
JP 2005-225370 A

  However, in the conventional control valve, since the cover member for holding the ball bearing is fixed to the housing by the bolt, the shaft center of the ball bearing accommodated in the cover member is processed in the threaded portion of the housing. It depends on the accuracy and the assembly accuracy of the cover member.

  For this reason, there are many causes of axial misalignment between the ball bearing housing portion of the cover member and the first bearing housing portion of the housing, and it is difficult to match the two shaft centers, and the input shaft is properly supported. Invited a technical challenge that could not be done.

  The present invention has been devised by paying attention to such a technical problem, and provides a control valve for hydraulic power steering capable of appropriately supporting the input shaft and suppressing the bending deformation of the input shaft. It is.

  In the present invention, hydraulic oil supplied from an external hydraulic power source is accommodated in each power cylinder according to the torsion amount of the torsion bar based on the relative rotation between the input shaft and the output shaft. A control valve for hydraulic power steering, comprising: a valve element that selectively supplies a pressure chamber; and a support member that closes one end opening of the housing and supports an input shaft by an inner peripheral portion, The support member is provided with a press-fitting portion, and the support member is press-fitted from the one end opening of the housing through the press-fitting portion.

  According to the present invention, by press-fitting a support member that supports the input shaft into the housing, the support member and the housing are integrally configured, and the shaft center of the support member and the housing can be aligned as much as possible. The input shaft can be properly supported by the support member.

  Hereinafter, an embodiment in which a control valve for hydraulic power steering according to the present invention is applied to a so-called rack and pinion type steering device will be described with reference to the drawings.

  First, a power steering apparatus to which a control valve according to the present invention is applied will be described. As shown in FIG. 1, an input shaft 1 whose one end is linked to a steering wheel (not shown), and the other end of the input shaft 1 Are connected via a torsion bar 2 and have an output shaft 3 having pinion teeth 3a on the outer periphery on the front end side, and rack teeth 4a meshing with the pinion teeth 3a in a predetermined range in the axial direction and extending in the vehicle body width direction. A rack shaft 4 whose both ends are linked to the left and right steered wheels via a knuckle (not shown), a power cylinder 5 configured using the rack shaft 4 as a piston rod, and hydraulic oil circulating in the power cylinder 5 are stored. A reservoir tank 6 to be driven, an oil pump 7 for sucking hydraulic oil from the reservoir tank 6 and pumping it to the power cylinder 5, and a torsion bar 2 being twisted. The shaft 1 and the output shaft 3 are opened and closed by relative rotation, and the amount of hydraulic oil supplied to the power cylinder 5 is controlled in accordance with the relative rotation amount of the both shafts 1 and 3 (the twist amount of the torsion bar 2). And a control valve 10 for performing.

  Based on this configuration, the power steering device changes the direction of the steered wheels by moving the rack shaft 4 in the axial direction along with the rotation of the output shaft 3 that rotates following the steering wheel. In addition, the control valve 10 assists the driver's steering operation by applying hydraulic pressure in the power cylinder 5 according to the rotational torque of the steering wheel based on the driver's steering operation.

  The input shaft 1 has a substantially cylindrical shape, and a torsion bar 2 is inserted on the inner peripheral side. One end of the torsion bar 2 is connected to one end of the input shaft 1 by a pin 8. . The input shaft 1 is housed at the other end in a housing 11 having an opening at one end, and the other end of the input shaft 1 constitutes a part of the control valve 10 inside the housing 11. The first rotor 1a is integrally formed.

  The output shaft 3 is entirely accommodated in the housing 11, and one end portion, an intermediate portion, and the other end portion are respectively provided by the first bearing 9a, the second bearing 9b, and the third bearing 9c accommodated and held in the housing 11. It is supported rotatably. Also, a second rotor 3b that has a substantially bottomed cylindrical shape and forms the control valve 10 in cooperation with the first rotor 1a is integrally formed in the housing 11 at one end side of the output shaft 3. The second rotor 3b is fitted on the first rotor 1a of the input shaft 1 and is superposed in the radial direction with respect to the first rotor 1a, thereby constituting the control valve 10 together with the first rotor 1a.

  The power cylinder 5 includes a cylinder tube 5a formed in a substantially cylindrical shape, a piston 5b provided in the cylinder tube 5a so as to be movable in the axial direction, and a non-illustrated fitting on the outer periphery of the piston 5b. A piston seal, and the cylinder tube 5a is separated into a first pressure chamber P1 on the left side and a second pressure chamber P2 on the right side in FIG. 5 by the piston seal.

  In other words, the power cylinder 5 is supplied with the hydraulic oil discharged from the oil pump 7 into the pressure chamber on the side that propels the rack shaft 4 among the pressure chambers P1 and P2, and the hydraulic oil in the pressure chamber on the opposite side. Is discharged to the reservoir tank 6 so that a propulsive force based on the differential pressure generated between the pressure chambers P1 and P2 is applied to the rack shaft 4.

  As shown in FIGS. 1 and 2, the control valve 10 is formed in a stepped diameter with respect to the one end opening 11a inside the housing 11 so as to face the one end opening 11a. The valve element 12 which is accommodated in the chamber 11b and includes the first rotor 1a and the second rotor 3b, and is press-fitted from the one end opening portion 11a, and the input shaft 1 is closed on the inner peripheral side while closing the one end opening portion 11a. A support member 13 that is rotatably supported, and a female screw portion 11c provided in a predetermined axial range on the opening side on the inner peripheral surface of the one end opening portion 11a, and is provided on one end side of the support member 13. A regulating member 14 that regulates axial movement of the support member 13 by being pressed against a receiving surface 13h (see FIG. 4) described later, and the regulating member 14 is fixed to the housing 11. It includes a lock nut 15 is fixed member.

  Further, as shown in FIG. 1, the control valve 10 includes a supply oil passage 20a communicating with the oil pump 7, a discharge oil passage 20b communicating with the reservoir tank 6, and a left side of the power cylinder 5 in the figure. A first oil passage 20c that communicates with the first pressure chamber P1 and a second oil passage 20d that communicates with the second pressure chamber P2 on the right side of the power cylinder 5 in the drawing are connected.

  The control valve 10 is connected to the supply and discharge oil passages 20a and 20b and the first and second oil passages 20c and 20d according to the rotation direction of the steering wheel, that is, the rotation direction of the input shaft 1 with respect to the output shaft 3. By selectively switching the connection, the hydraulic oil discharged from the oil pump 7 is selectively supplied to one pressure chamber of each of the pressure chambers P1 and P2 via the control valve 10 and the other pressure chamber. Is returned to the reservoir tank 6.

  The valve element 12 is supplied and discharged by selectively switching the circumferentially adjacent oil passages defined between the rotors 1a and 3b based on the relative rotation of the first rotor 1a with respect to the second rotor 3b. The oil passages 20a and 20b are configured to selectively connect the first and second oil passages 20c and 20d. The specific structure is the same as that of a known control valve (rotary valve). Since there is, explanation is omitted.

  As shown in FIGS. 2 to 6, the support member 13 is formed in a substantially cylindrical shape, and becomes a bearing holding portion that is formed in a reduced diameter by projecting inward in the radial direction at the inner periphery of the intermediate portion in the axial direction. A support portion 13a is provided. A bush 16 that is a bearing member formed in a substantially cylindrical shape by a resin material is fitted into the support portion 13a from the upper end side in the drawing. Further, the support portion 13a is provided with an annular locking projection 13b which is a protruding portion protruding inward at the lower end in the axial direction in the figure, and the locking projection 13b allows the bushing 16 to be The downward movement in the figure is restricted.

  The inner diameter R1 of the bearing 16 is set so that the radial clearance C1 between the bearing 16 and the input shaft 1 is larger than the valve clearance C2 that is the radial clearance between the rotors 1a and 3b. As a result, it is possible to ensure an appropriate valve clearance C2 without depending on the processing accuracy of the support member 13 and the bush 16, and the processing accuracy of the support member 13 and the bush 16 becomes the valve characteristic during normal use of the control valve 10. There is no risk of adverse effects.

  Further, the support member 13 is formed so that an outer peripheral portion corresponding to the support portion 13 a has a substantially arcuate longitudinal section, and an outer diameter of the protrusion is a shaft that is accommodated in the housing 11 of the support member 13. The maximum outer diameter R2 of the projecting portion is set to be slightly larger than the inner diameter R3 of the one end opening 11a of the housing 11, and the main portion is formed by the projecting portion. A press-fit portion 13c according to the invention is configured. That is, the support member 13 is press-fitted and fixed in the one end opening portion 11a of the housing 11 through the press-fit portion 13c based on such a configuration.

  An annular groove 13d continuous in the circumferential direction is formed in the outer peripheral surface on the other end side of the support member 13, and the elastic groove 13d is elastically formed on the inner peripheral surface of the one end opening 11a of the housing 11. An O-ring 17 that is a first seal member that contacts and holds the inside of the valve accommodating chamber 11b in a liquid-tight manner is fitted.

  Further, the other end side of the support member 13 is formed with a reduced diameter with respect to the vicinity of the press-fitting portion 13 c, and is a control valve with respect to the O-ring 17 between the inner peripheral surface of the one end opening portion 11 a of the housing 11. 10 is configured to form a hydraulic pressure introduction passage 18 for applying a hydraulic pressure in the inside. That is, by applying a hydraulic pressure to the O-ring 17 through the hydraulic pressure introducing passage 18, the O-ring 17 is bulged and deformed in a flat shape in the radial direction by the hydraulic pressure, and the O-ring 17 is formed on the bottom surface of the annular groove 13c. And the inner peripheral surface of the one end opening 11a of the housing 11 is more strongly biased, and the sealing performance of the O-ring 17 is improved by this hydraulic pressure introducing action.

  The other end surface of the support member 13 is provided with a substantially annular contact surface 13e that contacts the outer race of the first bearing 9a when the support member 13 is assembled to the housing 11. In the assembled state of the member 13, the support member 13 is fastened and fixed in the one end opening portion 11 a, whereby the outer race of the first bearing 9 a becomes a boundary between the one end opening portion 11 a and the valve accommodating chamber 11 b in the housing 11. It is clamped and fixed between the step part 11d formed in the part and the said contact surface 13e. Note that the inner race of the first bearing 9 a is clamped and fixed by a nut at a step provided at one end of the output shaft 3.

  Further, an annular groove 13f continuous along the circumferential direction is formed in the inner peripheral surface of one end portion of the support member 13, and the annular groove 13f is elastically contacted with the outer peripheral surface of the input shaft 1. An oil seal 19 that is a second seal member that holds the valve clearance C2 of the first rotor 1a and the second rotor 3b in a liquid-tight manner is fitted. That is, the oil seal 19 prevents the hydraulic oil from leaking to the outside through the valve clearance C2.

  On the other hand, the one end portion of the support member 13 is formed with a step reduced diameter portion 13g whose outer peripheral side is formed in a step reduced diameter with respect to the press-fit portion 13c. A plane continuous in the circumferential direction is configured as a receiving surface 13 h that receives an axial force from the regulating member 14.

  As shown in FIG. 6, the restricting member 14 has an annular recess 14 a provided in an enlarged diameter on the inner circumference on one end side, and the annular recess 14 a is a step-reduced diameter portion of the support member 13 during assembly. It fits on 13g. An annular convex portion 14b, which is a projecting portion projecting to the outer end side (axially outer side), is provided on the inner end surface of the annular concave portion 14a in a range where the oil seal 19 is overlapped in the axial direction in the assembled state. In this assembled state, the annular protrusion 14b is brought into contact with the outer end surface of the oil seal 19 held in the annular groove 13f of the support member 13, thereby preventing the oil seal 19 from falling off the annular groove 13f. Is planned.

  Further, the regulating member 14 has one end side screwed to the female screw portion 11c of the one end opening portion 11a of the housing 11 via a male screw portion 14c provided on the outer peripheral surface, and a lock nut screwed to the other end side. 15 is fastened to the housing 11, and the axial movement of the support member 13 is firmly restricted by the axial force of the restriction member 14 itself and the fastening force of the lock nut 15.

  In order to assemble the control valve 10 according to the present embodiment having the above-described configuration, first, as shown in FIGS. 1 and 2, the input shaft 1 and the output shaft 3 are connected by a torsion bar 2, and these are connected. The components constituting the valve element 12 are inserted into the housing 11 from the one end opening 11a while the pinion teeth 3a of the output shaft 3 are engaged with the rack teeth 4a of the rack shaft 4. Thereafter, the output shaft 3 is fixed to the step portion 11d with the nut via the first bearing 9a.

  Next, as shown in FIG. 5, the bush 16 is fitted into the support portion 13 a of the support member 13, and then the oil seal 19 is fitted into the annular groove 13 f of the support member 13. Further, after the O-ring 17 is fitted into the annular groove 13d of the support member 13, as shown in FIG. 7, the support member 13 is inserted from one end opening portion 11a of the housing 11, and is fitted to the outer periphery of the other end side. The support member 13 is temporarily assembled to the housing 11 by inserting the attached O-ring 17 until it passes through the female screw portion 11c and elastically contacts the inner peripheral wall of the one end opening portion 11a.

  At this time, the support member 13 inserted into the one end opening portion 11a is formed such that the outer diameter of the press-fitting portion 13c is maximized in the axial direction region and both ends are reduced in diameter with respect to the press-fitting portion 13c. Further, it is possible to suppress the hooking at the time of inserting the support member 13, and the insertion workability of the support member 13 is good. In addition, since the other end side of the support member 13 that is the side to be inserted has a shape that gradually decreases in diameter toward the insertion direction, the insertion workability of the support member 13 is further improved. .

  Subsequently, after the regulating member 14 is externally fitted to the step reduced diameter portion 13g of the supporting member 13, the regulating member 14 is tightened until one end surface thereof abuts on the receiving surface 13h of the supporting member 13, Screw onto the female thread 11c. Thereafter, a lock nut 15 is screwed onto the other end of the restricting member 14, and the lock nut 15 is tightened to fasten the restricting member 14 to the housing 11 as shown in FIG. Assembly is complete.

  Since the restriction member 14 is screwed into the one end opening 11a of the housing 11, the support member 13 is automatically press-fitted into the one end opening 11a by screwing the restriction member 14 as described above. Thus, the press-fit workability of the support member 13 is good. In other words, the assembly of the restriction member 14 and the assembly of the support member 13 can be performed at the same time only by the screwing operation of the restriction member 14, and the assembly workability of the control valve 10 can be improved.

  Therefore, according to the present embodiment, since the support member 13 is press-fitted and fixed to the one end opening portion 11a of the housing 11 via the press-fit portion 13a, the support member 13 is configured integrally with the housing 11. As a result, it is possible to make the axial center of the support member 13 and the one end opening 11a coincide as much as possible. As a result, the input shaft 1 can be properly supported by the support member 13 without depending on the processing accuracy or assembly accuracy of the support member 13.

  Further, since the press-fit portion 13c is formed on the outer peripheral surface of the support member 13, the load input from the inner peripheral side by the input shaft 1 is supported by the press-fit portion 13c on the outer peripheral side. Can be improved.

  Further, since the press-fitting portion 13c is formed so as to have a substantially arcuate longitudinal section, the contact area between the press-fitting portion 13c and the inner peripheral surface of the one end opening 11a of the housing 11 when the support member 13 is press-fitted. Can be reduced as much as possible. For this reason, it becomes possible to suppress generation | occurrence | production of the sludge by the said press injection, and mixing of the said sludge in the valve | bulb accommodating chamber 11b can be suppressed. Furthermore, by reducing the contact area, it is possible to reduce the press-fitting resistance when the support member 13 is press-fitted, and the press-fitting workability of the support member 13 can be improved.

  Further, since the support portion 13a is provided with the bush 16, it is possible to select a material different from the support member 13, that is, a material having a smaller friction coefficient than the support member 13 (for example, PTFE). The input shaft 1 can be supported more smoothly. Thereby, when the support member 13 receives the input of the radial direction from the input shaft 1, the influence on the valve characteristic by the said input can be restrained small.

  Further, since the restricting member 14 is used for fixing the support member 13, the shaft of the restricting member 14 is received even when a large input is received from the input shaft 1 or the output shaft 3 to release the press-fitting and fixing of the support member 13. The support member 13 can be held in the housing 11 by force.

  Further, since the lock nut 15 is used when the restriction member 14 is fixed, an excessive input is received from the input shaft 1 or the output shaft 3, and the press-fitting of the support member 13 and the axial force of the restriction member 14 become invalid. Even in this case, the support member 13 can be securely held in the housing 11 to ensure the valve function.

  Further, in the support member 13, the receiving surface 13h that receives the axial force of the regulating member 14 is formed in an annular shape, so that it is possible to secure a wider area of the receiving surface 13h. . Thereby, the reliability of the bearing surface strength of the regulating member 14 can be improved.

  The present invention is not limited to the configuration of the embodiment described above. For example, the shapes of the support member 13 and the regulating member 14 are appropriately changed according to the specifications of the control valve 10 and the power steering device using the control valve 10. Is possible.

  In particular, the shape of the press-fit portion 13c is not limited to a substantially circular arc shape in longitudinal section, and any configuration can be used as long as the contact area with respect to the inner peripheral surface of the one end opening portion 11a of the housing 11 can be reduced. It is also possible to adopt.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view showing an outline of a control valve provided in an embodiment of the present invention and a hydraulic power steering apparatus using the control valve. It is a principal part enlarged view of FIG. It is the A section enlarged view of FIG. It is a longitudinal cross-sectional view which shows a supporting member single-piece | unit. It is a longitudinal cross-sectional view which shows the assembly state of a support member and components accompanying this. It is a longitudinal cross-sectional view which shows a control member single-piece | unit. It is a longitudinal cross-sectional view which shows the assembly process of a control valve.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Input shaft 1a ... 1st rotor 2 ... Torsion bar 3 ... Output shaft 3b ... 2nd rotor 5 ... Power cylinder 7 ... Oil pump (hydraulic source)
DESCRIPTION OF SYMBOLS 10 ... Control valve 11 ... Housing 11a ... One end opening part 12 ... Valve element 13 ... Support member 13a ... Support part 13c ... Press-fit part 16 ... Bush (inner peripheral part of support member)
P1 ... 1st pressure chamber (pressure chamber of power cylinder)
P2 ... Second pressure chamber (Power cylinder pressure chamber)

Claims (10)

One end is linked to the steering wheel, and an input shaft that rotates by a steering force input from the steering wheel;
An output shaft that has one end connected to the input shaft through a torsion bar so as to be relatively rotatable, and rotates by a restoring force of torsional deformation of the torsion bar and outputs a steering force to a steered wheel linked to the other end;
A control valve for a hydraulic power steering used in a hydraulic power steering apparatus, including a power cylinder linked to the output shaft and generating a steering assist force by a differential pressure between two pressure chambers separated by a piston. And
A first rotor provided on the other end side of the input shaft and a first rotor provided on one end side of the output shaft so as to overlap in the radial direction with respect to the first rotor in a housing having an opening at least one end. The hydraulic oil supplied from an external hydraulic source is selectively supplied to each pressure chamber of the power cylinder according to the amount of twist of the torsion bar due to the relative rotation of the input shaft and the output shaft. A valve element;
Its outer peripheral surface longitudinal section is approximately one opening or al pressure of the housing via a press-fit portion formed in an arc shape input to, supporting the input shaft by the inner peripheral portion with closing one end opening of the housing A control valve for hydraulic power steering, comprising: a support member;   2. The control valve for hydraulic power steering according to claim 1, wherein a radial clearance between the support member and the input shaft is set larger than a radial clearance between the first rotor and the second rotor. . Wherein the outer diameter of the press-fitting direction leading end side of the support member, a hydraulic power steering control valve according to claim 1, characterized in that set smaller than the outer diameter of the press fit portion. 4. The control valve for hydraulic power steering according to claim 3 , wherein an outer diameter of the press-fit portion is set to be maximum in an axial region accommodated in the housing of the support member . 5. An annular groove is provided on the outer peripheral surface on the distal end side in the press-fitting direction with respect to the press-fitting portion of the support member, and an annular first seal member is fitted into the annular groove,
Hydraulic pressure acting to urge the first seal member toward the inner peripheral surface of the housing between the outer peripheral surface of the support member at the front end side in the press-fitting direction with respect to the annular groove and the inner peripheral surface of the housing. The hydraulic power steering control valve according to any one of claims 1 to 4 , further comprising a hydraulic pressure introduction passage for guiding the pressure . Said support bearing holding portion is provided on the inner periphery of the member, the hydraulic pressure according to any one of claims 1 to 5, characterized in that fitted the bearing member for supporting the input shaft to the bearing holder Control steering valve. 7. The hydraulic power steering control valve according to claim 6 , wherein a projecting portion projecting inward is provided at an end of the bearing holding portion opposite to the side on which the bearing member is fitted . The control for hydraulic power steering according to any one of claims 1 to 7 , wherein a restriction member for restricting axial movement of the support member is provided on a rear end side in the press-fitting direction of the support member. valve. 9. The control valve for hydraulic power steering according to claim 8 , wherein the support member is provided with an annular receiving surface that receives an axial force from the restricting member . Wherein between the support member and the regulating member, as claimed in claim 8 or 9, characterized in that a second sealing member for sealing a radial gap between the supporting member and the input shaft in a liquid tight manner Control valve for hydraulic power steering.

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