JPS6212708Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention comprises a first shaft and a second shaft coaxially supported within a housing, a conversion mechanism that converts rotational displacement between these two shafts into axial displacement, and this conversion mechanism. The present invention relates to a control valve for a power steering device equipped with a spool valve that is axially displaced in conjunction with a spool valve to switch a pressure oil supply flow path.

In conventional control valves of this type, for example, a ball, which is a component of the conversion mechanism, is held rotatably by a ball retainer ring, and is held in a spiral groove having a V-shaped cross section provided on either of the shafts. engaged. By the way, in this control valve, the distance from the center of the ball to the point contact point A between the ball and the ball retainer ring is longer than the distance from the center of the ball to the point contact point B between the ball and both wall surfaces of the spiral groove. When the ball slips, a large sliding friction force is generated at the point contact portion A, and a displacement regulating force against the spool valve, which is greater than this friction force, acts on the point contact portion B. As a result, the following various problems occur. That is, (1) the displacement of the spool valve is restricted, resulting in poor operability of the control valve, and wear occurs on both walls of the spiral groove.

(2) Due to wear on both walls, play occurs between the spiral groove, ball, and ball retaining ring, making it impossible to hold the spool valve at the set neutral position, resulting in a major change in the operating characteristics of the control valve. may damage the function of the control valve.

The present invention has been made in order to deal with such problems, and its gist is that a ball that engages with a spiral groove provided on either one of the two shafts is adopted as a component of the conversion mechanism, The ball is pressed into the helical groove by a retainer ring and a pressing member located inside the retainer ring and made of a material with a low coefficient of friction. Therefore, the pressing member of the present invention is made of a material with a low coefficient of friction, and such materials include fluorocarbon resin such as polytetrafluoroethylene, polycarbonate,
Synthetic resins such as polyacetal, nylon, and polyester, low-friction metals such as bronze for bearings, and sintered alloys are preferably used.

FIG. 1 shows an example of a control valve according to the present invention. This control valve 10 is used in a rack and pinion type power steering device, and a valve housing 11 of the control valve 10 is connected to a gearbox 1.
The input shaft 20 and the output shaft 30 are fluid-tightly inserted into the valve housing 11, and the needle bearing 12 and the ball bearing 1 are fluid-tightly fixed to the gear housing 110 of the valve housing 11.
It is coaxially supported via 3. Further, a cylindrical spool valve 40 is arranged within the valve housing 11 concentrically with the input shaft 20.

The input shaft 20 is pivotally supported at its lower end by the upper end of the output shaft 30 via a needle bearing 14, and is connected to the output shaft 30 by a torsion bar 21 inserted through its axis. This torsion bar 21 connects its upper end to the input shaft 22 with a pin 22.
It is assembled by connecting the upper end to the output shaft 30 and the lower end thereof to the upper end of the output shaft 30 using the pin 23. Further, as shown in FIGS. 1 and 2, a pair of spiral grooves 24 are provided on the lower outer periphery of the input shaft 20.
24 and a pair of notches 25, 25 are provided.

The output shaft 30 has at its upper end a pair of protruding pieces 31, 31 that protrude into each notch 25 of the input shaft 20, and a guide pin 32 is fixed to each of these protruding pieces 31 in the radial direction. . Each guide pin 32
are respectively fitted into a pair of axial guide grooves 41, 41 provided opposite to each other at the lower end of the spool valve 40, and guide the movement of the spool valve 40 in the axial direction. In addition, each protruding piece 3 of the output shaft 30
1 are arranged in each notch 25 of the input shaft 20 with a predetermined gap in the circumferential direction, thereby allowing the input shaft 20 and the output shaft 30 to rotate relative to each other. Note that a pinion 3 is provided at the lower end of the output shaft 30.
3 is provided, and this pinion 33 faces into the gear housing 110 and is connected to the gear housing 110.
It meshes with the rack of the steering rack 120 assembled inside.

The spool valve 40 has a pair of through holes 42, 42 provided at its lower end, and an upper annular groove 43a, a central annular groove 44a, and a lower annular groove 45a on its outer peripheral surface. The annular grooves 43a, 45a communicate with the inside of the spool valve 40 via through holes 43a, 45b. This spool valve 40 has a valve housing 11
The central annular groove 44a is slidably and rotatably fitted within the valve housing 11, and the central annular groove 44a is always in communication with the inlet port 11A provided in the valve housing 11. This inflow port 11A is connected to the upper annular groove 43a of the spool valve 40 via the central annular groove 44a and the upper annular groove 11e of the valve housing 11 when the spool valve 40 is in the neutral state (see FIG. 1). It communicates with the lower annular groove 45a of the spool valve 40 via the central annular groove 44a and the lower annular groove 11f of the valve housing 11. Therefore, the pressure oil that has flowed in from the inflow port 11A is returned to a reservoir (not shown) via the drain port 11B of the valve housing 11.
On the other hand, when the spool valve 40 is displaced upward,
Communication between the central annular groove 44a of the spool valve 40 and the lower annular groove 11f of the valve housing 11 is cut off. Therefore, the pressure oil flowing in from the inflow port 11A is supplied to one oil chamber of the power cylinder (not shown) through the upper annular groove 11e of the valve housing 11 and the first port 11C, and at the same time, the pressure oil is supplied to one oil chamber of the power cylinder (not shown). Pressure oil flows through the second port 11D of the valve housing 11, the lower annular groove 11f, and the lower annular groove 4 of the spool valve 40.
5a, and is further refluxed to the reservoir via the drain port 11B. In addition, the spool valve 40
is displaced downward, the pressure oil flowing in from the inflow port 11A is supplied to the other oil chamber of the power cylinder via the second port 11D, and at the same time, the pressure oil in one oil chamber of the power cylinder is supplied to the first port 11C and the drain. It is returned to the reservoir via port 11B.

Therefore, each through hole 42 of the spool valve 40
A ball 5, which is a component of the displacement conversion mechanism, is shown in FIG.
1 is fitted, and a portion thereof is engaged with the helical groove 24 of the input shaft 20. Further, the ball 51 is rotatably held by a holding member. This holding member is a retainer ring such as a snap spring 5.
2 and a pressing member 53. The pressing member 53 is made of a material with a lower coefficient of friction than the snap spring 52, and as shown in FIG. A fitting groove 53b for the snap spring 52 is provided on the back surface.
This pressing member 53 is inserted into the fitting groove 53 with its spherical contact surface 53a in contact with the outer periphery of the ball 51.
It is held elastically by a snap spring 52 fitted to b. As a result, the ball 51 is pressed against the spiral groove 24 of the input shaft 20.

In the control valve 10 configured in this manner, when the steering wheel (not shown) is operated, the input shaft 20 twists the torsion bar 21 and rotates relative to the output shaft 30, causing the ball 5 to rotate.
1 in the spiral groove 24 to displace the spool valve 40 upward or downward from its neutral position. As a result, the pressure oil flowing in from the inflow port 11A is transferred to the first port 11C or the second port 11.
D is supplied to the right or left oil chamber of the power cylinder, and at the same time, pressure oil in the left or right oil chamber is returned to the reservoir via the second port 11D or first port 11C, and the drain port 11B. Therefore, the steering operation of the steering wheel is significantly reduced. Note that when the steering operation of the steering wheel is stopped, the spool valve 40 is operated via the steering rack 120 to the output shaft 3.
0 returns to the neutral position by relative rotation with respect to the input shaft 20.

Incidentally, in the control valve 10, the holding member for the ball 51 is constituted by a snap ring 52 and a pressing member 53 made of a material having a lower coefficient of friction than the snap ring 52. For this reason,
Since the sliding friction force between the ball 51 and the pressing member 53 is small, the ball 51 rolls smoothly within the spiral groove 24,
Displacement of the spool valve 40 is not restricted, the operability of the control valve is good, and wear on both wall surfaces of the spiral groove 24 is suppressed. In addition, in the control valve 10, since the pressing member 53 is held elastically by the snap spring 52 and the ball 51 is pressed against the spiral groove 24, the spherical contact surface 53 of the pressing member 53
Even if wear occurs on a, the play caused by this wear is automatically eliminated. For this reason, spool valve 4
0 can be maintained at the set neutral position, the operating characteristics of the control valve 10 can be maintained well, and the operational feeling can be improved. Note that the control valve 10 does not require a highly accurate holding member.

FIG. 4 shows a modification of the holding member. This holding member includes a flexible retainer ring 54 having a wider width than the snap ring 52, and a pressing member 55 made of a material having a lower coefficient of friction than the retainer ring 54. As shown in FIG. 5, this retainer ring 54 has a pair of mutually opposing recesses 54a formed on its inner peripheral surface, and a mounting hole 54b is formed in each recess 54a, 54a. On the other hand, the pressing member 55 has a poppet shape as shown in FIG. 6, and has a spherical contact surface 55a that comes into contact with the outer periphery of the ball 51 on the front surface of its head, and its legs 55b are attached to the retainer. It can be fitted into the mounting hole 54b of the ring 54.
This pressing member 55 is elastically attached to the retainer ring 54 with its spherical contact surface 55a in contact with the outer periphery of the ball 51 and its legs 55b fitted into the mounting holes 54b of the retainer ring 54. This presses the ball 51 into the helical groove 24 of the input shaft 20. It should be noted that a control valve employing such a holding member functions in the same manner as the control valve 10 of the above embodiment, and has the same effects.

In addition, in the present invention, not only the control valve shown in the above embodiment but also a type control valve in which the spool valve is arranged in parallel with both shafts, A first shaft and a second shaft supported by a shaft, a conversion mechanism that converts the rotational displacement between these two shafts into an axial displacement, and a mechanism that displaces the pressure oil in the axial direction by linking with this conversion mechanism to open the pressure oil supply flow path. The invention can be implemented in various types of control valves of power steering systems equipped with switching spool valves.

In summary, the present invention employs a ball that engages with a spiral groove provided on either one of the shafts as a component of the conversion mechanism in the various types of control valves described above, and a retainer ring and the retainer. Its structural feature lies in that the ball is pressed into the helical groove by a pressing member located inside the ring and made of a material with a low coefficient of friction.
Therefore, according to the present invention, it is possible to suppress the displacement regulating force on the spool valve caused by the sliding friction force of the ball, thereby improving the operability of the control valve, and also automatically eliminating backlash. Good operating characteristics can be maintained.

[Brief explanation of the drawing]

FIG. 1 is a second diagram showing an example of a control valve according to the present invention.
FIG. 2 is a cross-sectional view taken along the - line in FIG. 1, FIG. 3 A is a front view of the pressing member, FIG. 3 B is a rear view thereof, and FIG. 3 C is the third
A side view in the direction of arrow C in Figure B, Figure 3D is Figure 3B
4 is a partial vertical sectional view showing a modified example of the holding member, FIG. 5A is a plan view of the retainer ring constituting the holding member, and FIG. Figure 6A is a front view of the pressing member constituting this holding member, Figure 6B is its rear view, and Figure 6C.
is its side view. Explanation of symbols, 10... Control valve, 20... Input shaft, 21... Torsion bar, 24... Spiral groove,
30...Output shaft, 40...Spool valve, 42
... Through hole, 51 ... Ball, 52, 54 ... Retainer ring, 53, 55 ... Pressing member.

Claims (1)

[Scope of utility model registration request] The first and second shafts are coaxially supported within the housing, a conversion mechanism that converts the rotational displacement between these two shafts into axial displacement, and the interaction with this conversion mechanism causes displacement in the axial direction to generate pressure. In a control valve for a power steering device equipped with a spool valve that switches an oil supply flow path, a ball that engages with a spiral groove provided on either one of the shafts is employed as a component of the conversion mechanism. . A control valve, characterized in that the ball is pressed into the spiral groove by a retainer ring and a pressing member located inside the retainer ring and made of a material with a low coefficient of friction.