JPS63546Y2 - - 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, as a conversion mechanism for this type of control valve, a spiral groove is provided on the outer periphery of one of the two shafts, and a ball is rotatably assembled to the spool valve and engages with the spiral groove from the outside. and a retaining means having a retainer ring arranged on the outer periphery of the spool valve so as to be restricted from moving in the axial direction and abutting the outer periphery of the ball on the inner periphery. There is. By the way, in this control valve, play (bumps) 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 fixed to the valve case 50 by a snap ring 52, allowing rotation and small movement of the output shaft 30 in the radial direction with respect to the valve case 50, and 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 pair of upper and lower snap springs 61 and 62 shown in FIGS. 1 and 4 are employed. The snap springs 61 and 62 have a circular cross section,
A pair of upper and lower annular stepped portions 40f and 40g provided on the outer periphery of the spool valve 40 and the outer periphery of the ball 41 are each contractably fitted and fixed, spaced apart from each other by a predetermined distance in the axial direction, and abut against the outer periphery of the ball 41, respectively. Ball 4 in the axial direction of spool valve 40
1 in a resilient manner. For this reason, the ball 41
is urged toward the spiral groove 20a, and the spiral groove 20a
is under pressure. Incidentally, when implementing the present invention, it is also possible to employ snap rings 161, 162 shown in FIG. 5 in place of the snap rings 61, 62. Snap spring 161, 16
2 has a rectangular cross section with tapered surfaces 161a and 162a, and the annular stepped portion 40f of the spool valve 40,
40g and the outer periphery of the ball 41, each of which is retractably fitted and fixed at a predetermined distance in the axial direction, and abuts the outer periphery of the ball 41 at the tapered surfaces 161a and 162a, so that the ball 41 is compressible in the axial direction of the spool valve 40. holding it elastically.

In this embodiment configured in this manner, 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 of 0, etc., 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 boat 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 ball 41 is pressed against the spiral groove 20a by the tension force of both the snap springs 61, 62 (or 161, 162), so the ball 41 does not wobble, and problems caused by rattling are avoided. Does not occur. Furthermore, in this embodiment, since the balls 41 are pressed along the radial direction of the spool valve 40, the displacement of the spool valve 40 in the axial direction due to the relative rotation of the shafts 20 and 30 is changed upwardly and downwardly. There is no imbalance between the displacement and the displacement. Therefore, in this embodiment, the hydraulic characteristics and operational feeling of the control valve 10 are improved compared to the conventional one. In addition, in this embodiment, if manufacturing errors or wear due to use occur in the spiral groove 20a, the ball 41, etc.,
Along with this, the snap springs 61 and 62 (or 161 and 162) expand and contract in the radial direction to prevent play from occurring without causing any movement of the ball 41 in the axial direction and automatically adjust to the above-mentioned state.

The above explanation is based on one embodiment of the present invention, and the present invention is not limited to the above embodiment. a conversion mechanism that converts the displacement into an 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 displaceable in the axial direction in cooperation with the conversion mechanism to open the pressure oil supply flow path. The present invention can be implemented by appropriately changing to various control valves equipped with switching spool valves.

In summary, in the present invention, in the various types of control valves described above, the conversion mechanism includes a spiral groove provided on the outer periphery of one of the shafts, and a spiral groove rotatably assembled to the spool valve. and a ball that is provided at a predetermined distance in the axial direction on the outer periphery of the spool valve and abuts on the outer periphery of the spool valve and the ball, respectively, to elastically sandwich the ball in the axial direction. Its structural feature lies in the adoption of a conversion mechanism comprising a pair of snap springs, which allows the ball to be pressed into the spiral groove and eliminates the play that occurs around the ball by moving it in the axial direction of the ball. It can be automatically removed without causing any problems, and the hydraulic characteristics and operational feeling of the control valve can be maintained satisfactorily for a long period of time.

In addition, in the present invention, since the member used to remove the above-mentioned backlash is a pair of snap springs, the structure is simple and can be implemented at low cost. The ball can be positioned more accurately in the axial direction.

[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. Figure 2 is a cross-sectional view taken along the - line in Figure 1, Figure 3 is a cross-sectional view taken along the - line in Figure 1, Figure 4 is an enlarged longitudinal cross-sectional view of the main part of Figure 1, and Figure 5 is a modified version. It is an enlarged vertical cross-sectional view of the same essential part showing an example. 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, 61,
62...A pair of snap rings.

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 shafts and a rotatable groove in the spool valve. a ball that is assembled into the spool valve and engages with the spiral groove from the outside; A control valve for a power steering device, characterized in that it employs a conversion mechanism comprising a pair of snap springs that are elastically sandwiched in a direction.