JPS63543Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention includes 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 a A spool in a control valve of a power steering device, comprising a spool valve displaceable in the axial direction on one outer periphery of the spool valve, the spool valve being displaceable in the axial direction in conjunction with the conversion mechanism to switch the pressure oil supply flow path. This invention relates to a valve displacement conversion mechanism.

In conventional control valves of this type, for example, a ball, which is a component of the conversion mechanism, is rotatably held 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. Therefore, in order to improve the displacement conversion efficiency of the spool valve and improve the operability of the control valve, it is necessary to make the balls roll smoothly in the spiral groove, and to ensure the smooth rolling of the balls. To achieve this, it is essential to form a minute gap between the balls and the ball retainer ring that allows the balls to roll. However, if this minute gap is large, the ball can move in the radial direction of the input shaft, and the point contact between the ball and both side walls of the V-shaped spiral groove changes, and the spool valve is held at the set position. without damaging the operating characteristics of the control valve. Furthermore, if the minute gap is extremely small or nonexistent, smooth rolling of the balls cannot be ensured, and the displacement conversion efficiency of the spool valve decreases.
Abrasion causes play between the spiral groove, the ball, and the ball retainer ring, impairing the operating characteristics of the control valve. For this reason, in conventional control valves of this type, it is necessary to secure a predetermined minute gap between the ball and the ball retainer ring, and in order to cope with this, an extremely high precision ball retainer ring is required. This inevitably increases the cost of the control valve.

The present invention was developed in light of these circumstances, and its purpose is to provide control that provides good operability and maintains good operating characteristics without using a high-precision retainer ring. In other words, it is an object of the present invention to provide a control valve that has good operability and can maintain good operating characteristics at a low cost.

Hereinafter, the present invention will be explained based on the drawings. FIG. 1 shows an example of a control valve embodying 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 fluid-tightly fixed to a gear housing 110 of a gearbox 100. , an input shaft 20 and an output shaft 30 are inserted fluid-tightly and coaxially supported via a needle bearing 12 and a ball bearing 13. Further, inside the valve housing 11, a cylindrical spool valve 40 and a valve case 5 are arranged concentrically with the input shaft 20.
0 is arranged.

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, on the lower outer periphery of the input shaft 20, as shown in FIGS. 1 to 3, a pair of spiral grooves 24, 24 are provided.
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 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 is fitted into the valve case 50 so as to be movable in the axial direction. Further, on the outer peripheral surface of the spool valve 40, an upper annular groove 43a, a central annular groove 44a, and a lower annular groove 4 are provided.
5a is provided. In addition, both upper and lower annular grooves 43
a, 45a communicate with the inside of the spool valve 40 via through holes 43b, 45b.

The valve case 50 has a central annular groove 51a constantly communicating with the inflow port 11A of the valve housing 11 on its outer peripheral surface, and a first annular groove 51a of the valve housing 11.
Upper annular groove 52a constantly communicating with port 11B
A lower annular groove 53a is provided which constantly communicates with the second port 11C of the valve housing 11. In addition, a spool valve 40 is provided on the inner circumferential surface.
An upper annular groove 52b selectively communicates with the upper and central annular grooves 43a and 44a, and a lower annular groove 53b selectively communicates with the central and lower annular grooves 44a and 45a.
a and 52b communicate through a through hole 52c, and lower annular grooves 53a and 53b communicate through a through hole 53c. As shown in FIGS. 1 and 4, the valve case 50 is fixed in a predetermined position by engagement with a support member 34 that is relatively rotatably fitted to the upper end of the output shaft 30. Groove 51
a is always in communication with the central annular groove 44a of the spool valve 40 via the through hole 51c. Further, when the spool valve 40 is in the neutral state (see FIG. 1), the central annular groove 44a of the spool valve 40 is connected to the upper and lower annular grooves 52a of the valve case 50,
It communicates with the upper and lower annular grooves 43a and 45a of the spool valve 40 via 53a. As a result, the pressure oil from the inflow port 11A is transferred to the spool valve 4.
0 and returns to the reservoir via the drain port 11D of the valve housing 11. Note that when the spool valve 40 is displaced upward, the pressure oil from the inflow port 11A flows through the through hole 52c and the first port 1.
1B to one oil chamber of the power cylinder, and at the same time, pressure oil in the other oil chamber of the power cylinder is returned to the reservoir via the second port 11C, the through hole 53c, and the drain port 11D. Also,
When the spool valve 40 is displaced downward, the pressure oil from the inflow port 11A is supplied to the other oil chamber of the power cylinder through the through hole 53c and the second port 11C, and at the same time, the pressure oil in one oil chamber of the power cylinder is supplied to the other oil chamber of the power cylinder. The water is returned to the reservoir via the first port 11B, the through hole 52c, and the drain port 11D.

Therefore, both spiral grooves 2 in the control valve 10
4, as shown in FIGS. 2 and 3, both side walls are formed into U-shaped grooves in cross section parallel to each other along the radial direction of the input shaft 20 passing through the center of the spiral groove, and each spiral groove The inner ends of the pin rollers 61 inserted into the respective through holes 42 of the spool valve 40 face inside the grooves 24 . As shown in FIGS. 5 and 6, the pin roller 61 has a cylindrical shape with substantially hemispherical ends 61a and 61b, and is inserted into each through hole 42 of the spool valve 40 so that its inner end 61a
It is formed so that it can roll in a state where it faces into each spiral groove 24. The pin roller 61 is rotatably held in place by a retainer ring 63 attached by a circlip 62 that fits into each annular attachment groove of the spool valve 40.

In the control valve 10 configured in this manner, when a steering wheel (not shown) is operated, the input shaft 20 rotates relative to the output shaft 30 while twisting the torsion bar 21, and the pin roller 61 is moved into the spiral groove 24. to displace the spool valve 40 upward or downward from its neutral position. Therefore, the pressure oil flowing in from the inflow port 11A is supplied to the right or left oil chamber of the power cylinder (not shown) through the first port 11B or the second port 11C, and at the same time, the pressure oil in the left or right oil chamber is supplied to the second port 11B or the second port 11C. 11C, the first port 11B, and the drain port 11D, the water is returned to a reservoir (not shown). As a result, the steering operation force of the steering wheel is significantly reduced. In addition, in steering operation of the steering wheel,
The spool valve 40 displaced from the neutral position is returned to the neutral position by the relative rotation of the output shaft 30 with respect to the input shaft 20 via the steering rack 120.

By the way, in the control valve 10, both the spiral grooves 24 are formed into U-shaped cross sections as described above, and the pin rollers 61 are used as rolling members. Therefore, the pin roller 61 rolls smoothly within the spiral groove 24, and the side wall of the spiral groove 24 and the pin roller 61 are always in line contact, so even if the pin roller 61 moves slightly in the axial direction, The spool valve 40 merely moves on the same line of contact, and the spool valve 40 is held at the set position. Therefore, the pin roller 61 rolls smoothly to ensure good operability of the control valve 10, and even if there is slight variation in the minute gap, the operational characteristics of the control valve 10 are maintained well without being impaired. be done. Therefore, the retainer ring 63 does not need to be of high precision, and a control valve that has good operability and can maintain good operating characteristics can be provided at a low cost.

Note that the pin roller 61 can be modified as shown in FIGS. 7 and 8. This pin roller 61 has a cylindrical shape with an inner end 61a formed into a spherical shape and an outer end 61b formed into a hemispherical shape, and functions similarly to the pin roller shown in the first embodiment.

The present invention 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 an outer periphery of one of the two shafts. The present invention can be implemented in various types of control valves of power steering devices including a spool valve that is arranged to be displaceable in the axial direction and that is displaceable in the axial direction to switch the pressure oil supply flow path in conjunction with the conversion mechanism. .

In summary, in the present invention, in the various types of control valves described above, the conversion mechanism is replaced by a spiral groove provided on the outer periphery of one of the two shafts and having both side walls parallel to each other, and the spool valve. A pin roller is movably assembled and engages with the spiral groove on its parallel side wall, and a retainer ring is assembled around the outer periphery of the spool valve to prevent the pin roller from coming off. There is. Therefore, according to the present invention, it is possible to provide a control valve that has good operability and can maintain good operating characteristics without using a high-precision holding member, and to provide this type of control valve at a low cost. can do.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional view taken along the - line in Fig. 2 showing an example of a control valve embodying the present invention;
3 is a partially enlarged view of FIG. 2, FIG. 4 is a cross sectional view taken along line - of FIG. 1, FIG. 5 is an enlarged side view of the pin roller, and FIG.
The figure is a front view thereof, FIG. 7 is an enlarged side view showing a modified example of the pin roller, and FIG. 8 is a front view thereof. Explanation of symbols, 10... Control valve, 20... Input shaft, 21... Torsion bar, 24... Spiral groove,
30...Output shaft, 40...Spool valve, 50
...Valve case, 61...Pin roller, 63...
...retainer ring.

Claims (1)

[Scope of utility model registration request] A first shaft and a second shaft coaxially supported within the housing, a conversion mechanism that converts the rotational displacement between these two shafts into axial displacement, and one of the two shafts that can be displaced in the axial direction on the outer periphery thereof. In the control valve of the power steering device, the control valve is provided with a spool valve that is disposed in the axial direction and switches the supply flow path of pressure oil in conjunction with the conversion mechanism. a spiral groove provided on the outer periphery and having both side walls parallel to each other; a pin roller that is rotatably assembled to the spool valve and engages the spiral groove with its parallel side walls; and an outer periphery of the spool valve. A spool valve displacement conversion mechanism characterized in that it is configured to include a retainer ring that is assembled to the pin roller and prevents the pin roller from coming off.