JPS63547Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a control valve for a power steering device.

A control valve of a power steering device generally includes a first shaft and a second shaft that are coaxially supported within a housing, a conversion mechanism that converts rotational displacement between these two shafts into axial displacement, and a conversion mechanism that converts rotational displacement between these two shafts into axial displacement. A spool valve is disposed so as to be displaceable in the axial direction on the outer periphery of one side, and is displaceable in the axial direction in conjunction with the conversion mechanism to switch the pressure oil supply flow path. Conventionally, the conversion mechanism of this type of control valve includes a spiral groove provided on the outer periphery of one of the two shafts, and a ball that is rotatably assembled to the spool valve and engages with the spiral groove.
a retainer ring disposed on the outer periphery of the spool valve, fixed immovably to the spool valve in the axial direction using a positioning fixture, and having an inner periphery abutting against the outer periphery of the ball; There is a control valve that uses the following conversion mechanism. by the way,
In this control valve, play (backlash) may inevitably occur around the ball due to its structure. There is also an increase in backlash due to wear of each member. This backlash prevents the spool valve from displacing in the axial direction within a small relative rotation range between the two shafts, and also prevents spool valve vibration (vibration caused by the hydrodynamic axial force acting on the spool valve). This will adversely affect the hydraulic characteristics and operating feeling of the control valve.

The present invention has been devised to solve this problem in the above-mentioned conversion mechanism, and one embodiment thereof will be described below with reference to the drawings. Figure 1 shows easy
A part of a pinion type power steering device is shown, and a control valve 10 according to the present invention shown here has a valve housing 12 that is fluid-tightly fixed to a gear housing 11. Valve housing 12
are an inlet port 12a connected to a hydraulic pump (not shown), a port 12b connected to one oil chamber of a known hydraulic cylinder (not shown), and a port connected to the other oil chamber of the hydraulic cylinder. 12
c, and an outlet port 12d connected to a reservoir (not shown), and an input shaft 20.
and the output shaft 30 are coaxially supported. Further, inside the valve housing 12, a cylindrical spool valve 40 and a valve case 50 are arranged concentrically with the input shaft 20.

The input shaft 20 is formed in a hollow shape, is rotatably supported by the valve housing 12 via a needle bearing 21 at the center, and is connected to the upper end of the output shaft 30 via the needle bearing 22 at the lower end. and the torsion bar 23 inserted inside.
It is connected to the output shaft 30 by. The torsion bar 23 is connected at its upper end to the upper end of the input shaft 20 by a pin 24, and at its lower end to the output shaft 30 by a pin 25. Also,
As shown in FIG. 2, a pair of spiral grooves 20a, 20 having a V-shaped cross section are formed on the lower outer periphery of the input shaft 20.
a and a pair of notches 20b, 20 extending in the axial direction.
b, and a ball 41 fitted into a spool valve 40 is rotatably engaged with each spiral groove 20a. Note that the upper part of the input shaft 20 protrudes outside the valve housing 12 through the seal member 26 and is connected to a steering wheel (not shown).

The output shaft 30 is fluid-tightly sealed and extends into the gear housing 11, is rotatably supported by both housings 11 and 12 via a ball bearing 31 at the upper end, and is supported by a ball bearing 32 at the lower end. It is rotatably supported by the gear housing 11 via. This output shaft 30 is a pinion 30a
The pinion 30a meshes within the gear housing 11 with a rack 13 formed integrally with a part of the steering linkage (which is pushed by the operation of a hydraulic cylinder). Further, the output shaft 30 has a pair of protruding pieces 30 at its upper end that protrude into the respective notches 20b, 20b of the input shaft 20.
b, 30b, and each of these protruding pieces 30b
A predetermined gap (a gap that allows relative rotation between the input shaft 20 and the output shaft 30) is provided in the circumferential direction between the notches 20b and the notches 20b. Further, a guide pin 33 is fixed to each projecting piece 30b in the radial direction, and each guide pin 33 has a pair of axial guide holes 40a provided opposite to the lower end of the spool valve 40.
40a, and convert relative rotation of the input shaft 20 and output shaft 30 into axial displacement of the spool valve 40 in cooperation with the spiral grooves 20a, 20a, balls 41, 41, etc. do.

The spool valve 40 is fitted into the valve case 50 so as to be movable in the axial direction, and a pair of through holes 40b, 40b into which the balls 41 are fitted in a rolling manner are provided in the lower end thereof in the radial direction. ing.
Also, an annular groove 4 is formed on the upper outer periphery of the spool valve 40.
0c, 40d, and 40e are formed, and the upper and lower annular grooves 40c, 40e communicate with the inner hole of the spool valve 40 through the communication hole.

The valve case 50 is fluid-tightly incorporated into the valve housing 12, and is connected to the output shaft 30 via a thrust plate 51 at its lower end. The thrust plate 51 is shown in FIGS.
As shown in the figure, the output shaft 30
is rotatably fitted into an annular groove 30c provided in the
The outer peripheral portion of the output shaft 30 is fitted into a notch 50j of the valve case 50, and is fixed to the valve case 50 by a snap ring 52, allowing rotation of the output shaft 30 with respect to the valve case 50 and slight movement in the radial direction. Connect the valve case 50 to the output shaft 30
It is fixed at a predetermined position in the axial direction. Also, on the inner periphery of the upper part of the valve case 50, a first
an annular groove 50a that communicates with the annular grooves 40c and 40d of the spool valve 40 in the illustrated neutral position;
An annular groove 50b is formed which communicates with the annular grooves 40d and 40e of the spool valve 40.
0a communicates with the port 12b of the valve housing 12 through the communication hole 50c and the annular groove 50d, and the annular groove 50b communicates with the port 12c of the valve housing 12 through the communication hole 50e and the annular groove 50f. The valve case 50 also includes a radial communication hole 50g and an annular groove 50h that communicate the annular groove 40d of the spool valve 40 with the inlet port 12a of the valve housing 12, and a communication hole 50i that communicates the inside and outside of the valve case 50. is formed.

Therefore, in this embodiment, the balls 41,
41 from the outside of the spool valve 40, a single snap ring 60 having an abutment 60a is employed. The snap spring 60 is fitted into an annular groove 40f formed on the outer periphery of the spool valve 40 in such a manner that movement in the axial direction is restricted and expansion and contraction in the radial direction is allowed. The balls 41, 41 are brought into contact with the outer peripheries of the balls 41, 41 in a helical groove 20.
a, 20a. In this embodiment, the lower guide pin 33 in FIG. are doing.

In this embodiment configured as described above, when the spool valve 40 is in its neutral position, the hydraulic oil supplied from the hydraulic pump to the inlet port 12a passes through the annular groove 50h and the communication hole 50g of the valve case 50. and flows into the annular groove 40d of the spool valve 40, and the annular groove 5 of the valve case 50.
0a, flows into the spool valve 40 through the annular groove 40c of the spool valve 40, and the communication hole, while flowing into the spool valve 40 through the annular groove 50b of the valve case 50, the annular groove 40e of the spool valve 40, and the communication hole. Inflow, spool valve 4
0 guide holes 40a, 40a, etc. and valve case 5
The water flows back from the outlet port 12d to the reservoir through the communication hole 50i and the like, and is not supplied to the hydraulic cylinder. Therefore, the hydraulic cylinder does not operate.

In this state, the input shaft 20 is moved to the torsion bar 23 by rotating the steering wheel.
When the ball 41 rotates relative to the output shaft 30 while twisting, the ball 41 moves along the spiral groove 20a,
At the same time, the spool valve 40 opens its guide hole 4.
0a, is displaced upward (or downward) from its neutral position while being guided by the guide pin 33, and the annular groove 4
0c and 50a and annular grooves 40d and 50b (or annular grooves 40e and 50b and annular grooves 40d and 50a)
communication is cut off, inlet port 12a communicates with port 12b (or port 12c), port 12c (or port 12b) communicates with outlet port 12d, and hydraulic oil flowing from the hydraulic pump through inlet port 12a is supplied to one oil chamber (or the other oil chamber) of the hydraulic cylinder through port 12b (or port 12c), and at the same time, from the other oil chamber (or one oil chamber) of the hydraulic cylinder to port 12c (or port 12b)
The hydraulic oil flowing through the outlet port 1
Reflux to the reservoir through 2d. As a result, the hydraulic cylinder is actuated to push the rack 13 and reduce the operating force of the steering wheel. In addition, in this operation, the input shaft 20 stops by stopping the rotation operation of the steering wheel, and the output shaft 30 rotated by the rack 13 rotates relative to the input shaft 20, thereby moving the spool valve 40 to the neutral position. It stops by returning to .

By the way, in this embodiment, the tension force of the snap spring 60 causes the ball 41 to move into the spiral groove 20a.
The ball 41 is pressed so that it does not wobble, and problems associated with wobbling do not occur. Further, in this embodiment, the ball 41 is connected to the spool valve 4.
Since it is pressed along the radial direction of 0, both shafts 2
In the displacement conversion of the spool valve 40 in the axial direction due to the relative rotation of 0.0 and 30 degrees, the upward displacement and downward displacement do not become unbalanced. Therefore, in this embodiment, the hydraulic characteristics and operational feeling of the control valve 10 are improved compared to the conventional one. Further, in this embodiment, the spiral groove 20
a. If manufacturing errors or wear due to use occur in the ball 41, etc., the snap spring 60 expands and contracts in the radial direction, preventing play from occurring in the ball 4.
1 without any axial movement and automatically adjusts to the above-mentioned state.

Note that the present invention is not limited to the above-mentioned embodiments, and includes a first shaft and a second shaft coaxially supported within the housing, a conversion mechanism that converts rotational displacement between these two shafts into axial displacement, and Various control valves may be used as appropriate, including a spool valve disposed on the outer periphery of one of the shafts so as to be displaceable in the axial direction and displaceable in the axial direction in conjunction with the conversion mechanism to switch the pressure oil supply flow path. It can be implemented by

In short, in the present invention, in the various control valves described above, the conversion mechanism includes a spiral groove provided on the outer periphery of one of the two shafts, and a spiral groove that is rotatably assembled to the spool valve and connected to the spiral groove. A ball to be engaged and a ball disposed on the outer periphery of the spool valve such that the axial movement of the two shafts is regulated by the engagement with the spool valve, and the expansion and contraction in the radial direction is allowed. Its structural feature lies in the adoption of a conversion mechanism comprising a single snap spring that contacts elastically.
As a result, the ball can be pressed into the spiral groove, and the play that occurs around the ball can be automatically removed without axial movement of the ball, improving the hydraulic characteristics and operation feeling of the control valve. can be maintained well for a long period of time.

In addition, in the present invention, the ball holding means adopted to eliminate the above-mentioned backlash is the above-mentioned single snap spring, so the number of parts and assembly man-hours are reduced compared to those that use a pair of snap springs. Of course, it is possible to
Compared to the conventional holding means equipped with a retainer ring and positioning fixture to hold the ball, the number of parts and assembly man-hours can be reduced, and costs can be reduced.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing an embodiment of the present invention, and is an expanded longitudinal cross-sectional view taken along the line - in FIG. 2 is a cross-sectional view taken along the - line in FIG. 1, and FIG. 3 is a cross-sectional view taken along the - line in FIG. Explanation of symbols, 10... Control valve, 11... Gear housing, 12... Valve housing, 20...
Input shaft, 20a... spiral groove, 30... output shaft, 4
0...Spool valve, 41...Ball, 60...
...Snat Spring.

Claims (1)

[Scope of utility model registration request] A first shaft and a second shaft coaxially supported within the housing.
a shaft, a conversion mechanism that converts rotational displacement between these two shafts into axial displacement, and a conversion mechanism disposed on the outer periphery of one of the two shafts so as to be displaceable in the axial direction, and displaced in the axial direction by cooperation with the conversion mechanism. In a control valve for a power steering device equipped with a spool valve that switches the supply flow path of pressure oil, the conversion mechanism includes a spiral groove provided on the outer periphery of one of the two shafts and a rotatable groove in the spool valve. a ball that is assembled into the spool valve and engages with the helical groove; and a ball that is attached to the outer periphery of the spool valve so that movement of the two shafts in the axial direction is restricted by engagement with the spool valve, and expansion and contraction in the radial direction is allowed. 1. A control valve for a power steering device, characterized in that a conversion mechanism is employed, the conversion mechanism comprising a single snap spring disposed at the top of the ball and elastically abutting on the outer periphery of the ball.