JPS5853564A - Power steering device - Google Patents

Abstract

PURPOSE:To smooth the variation of the opening area of the flow passage of pressure oil and consequently the controlling of oil flow rate by a structure wherein the center lines of the oil grooves provided in the rotor, which controls the flow rate of pressure oil, of a rotary control valve is so arranged as to cross the center line of the oil groove provided in a valve body. CONSTITUTION:The oil grooves 11 are axially provided throughout nearly whole the length of the rotor 10 of the rotary control valve. The oil grooves 11 are provided with a certain inclination angle to the axis center of the valve body, to which the rotor 10 is fitted. Accordingly, the center lines of the oil grooves 11 of the rotor 10 and the center line of the coil groove of the valve body are arranged so as to cross each other. Owing to the structure as described above, the state of the variation of the opening area of the flow passage of pressure oil or of pressure with the angle of rotation of the rotor 10 can be made smoother as indicated with the dotted line than that in case of conventional rotor as indicated with the solid line.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a power steering device in which an input shaft and an output shaft are connected on the same axis via a torsion bar, and a rotor that rotates together with the input shaft and a rotor that rotates freely. A rotation control valve is constructed from a valve body that is fitted and rotates together with the output shaft, and the valve body is provided with grooves for supplying and discharging pressure oil from a hydraulic pump to a hydraulic cylinder for assisting steering operation. This invention relates to a power steering device that operates an output shaft system by controlling the opening amount of a discharge groove according to the relative rotational position between a valve body and a rotor by twisting a torsion bar according to a load on an output shaft. .・ Conventionally, in this type of power steering device, when the input shaft and output shaft are connected via a torsion bar, the torsion bar twists according to the load on the output shaft, and the torsion is used to connect the input shaft to the output shaft. A rotary control valve consists of a rotor that rotates with the rotor and a valve body that rotates with the output shaft, so the opening amount of the discharge groove in the valve body is controlled according to the relative rotational position between the rotor and the valve body, and the output is controlled. Controls the axis system. At this time, the steering force to operate the input shaft,
The torsion angle of the torsion bar is proportional to the load on the output shaft, and the hydraulic characteristics of a power steering device having a rotation control valve are determined by the relationship between the rotation angle of the rotor with respect to the valve body and the opening area. In conventional technology, the oil grooves of the rotor that control pressure oil are arranged parallel to the grooves of the valve body, so sudden changes in oil pressure occur due to the positional relationship due to relative rotation between the rotor and the valve body. The scope of what can be done is limited.

Generally, the following relationship exists between the opening area of a pressure control valve and the pressure.

2・△P Q=“°S°　.

Here, Q = flow rate α = flow coefficient S = opening area P = pressure difference ρ = kinematic viscosity According to this relational expression, when the flow rate is constant, the pressure is inversely proportional to the square of the opening area. Further, the hydraulic pressure of the power steering device is generally used at a pressure of 100 Kf/cd or less, and the opening area of the pressure control valve at this time is about 0.8 to 10 −.

Therefore, if the oil groove provided in the rotor is arranged parallel to the groove in the valve body, the rotation angle of the oil groove in the rotor with respect to the groove in the valve body that creates the opening area of this control valve will be small, and the oil pressure Changes occur rapidly, and the rotor requires high-precision machining, resulting in high costs and problems as a power steering device. Therefore, in the past, a hydraulic control edge was machined shallowly in an arc shape along the entire length of the groove on the edge of the oil groove of the rotor that was provided parallel to the axis of the rotor to control the pressure oil. was made gentler and the control range was wider (Patent Application No. 79988, 1982). However, even with this method, the hydraulic control range is narrow, and machining an arcuate hydraulic control edge over the entire length of the dowel groove on the edge of the oil groove of the rotor has the drawback of increasing costs.

The present invention provides a power steering device having a rotation control valve constituted by a valve body and a rotor, in order to eliminate the drawbacks of the above-mentioned well-known techniques and to supply and discharge pressure oil to the power steering device as desired. The challenge is to provide the following.

This problem is solved by the configurations described in the characterizing part of the claims. That is, the present invention provides a rotary control valve having a rotor having an oil groove in which the rotor is inclined with respect to the axis of the valve body. Provided is a rotary control valve having a valve body having an oil groove provided therein. By doing so, it is possible to provide a power steering device equipped with a low-cost rotary control valve that solves the conventional problems and has a smooth control range over a wide range.

Next, the present invention will be explained in detail with reference to drawings showing embodiments.

As shown in FIG. 1, the rotor 2 is fitted into a valve body 1 connected to an output shaft (not shown) and to an input shaft (not shown) via a torsion bar 3. The valve body I B is fitted into the pulp housing, and the input shaft and output shaft do not perform relative rotational movement in the radial direction due to bearings provided in the valve housing or the case of the power steering device connected thereto, respectively. The illustrated arrows in FIG. 1 indicate the supply and discharge of pressure oil from the hydraulic pump, and pressure oil is supplied from the supply hole 4 through a ring-shaped groove (not shown) formed on the inner diameter surface of the pulp housing. The supply receiver returns the pressure oil to the oil reservoir of the hydraulic pump through a ring-shaped groove 5 formed between the rotor 2 and the torsion pad 3.

Holes 6.7 indicated by dotted lines and dashed-dotted lines are respectively connected to ring-shaped grooves formed on the inner diameter surface of the valve body 1, and are respectively connected to the pistons of hydraulic cylinders that hydraulically operate the output shaft side of the power steering device. Connected to the right or left pressure chamber.

In this case, the supply hole 5 and the ring-shaped groove for controlling the hydraulic cylinder are provided at intervals in the axial direction of the pulp body 1. FIG. 2 shows a rotor having an oil groove provided in an open hearth with respect to the axis of the valve body. As is clear from this figure, the oil groove 9 of the rotor 8 is parallel to the axis of the rotor 8 and extends over the entire length of the rotor.

The control characteristics expressed by the angle, pressure, and opening area are shown by solid lines in FIG.

FIG. 3 shows a cross-sectional view of a rotary control valve using the rotor shown in FIG. The rotor shown in FIG. 4 is an embodiment of the present invention having long grooves inclined with respect to the valve body. An oil groove 11 is provided over almost the entire length of the valve body, and this oil groove 11 is provided at an angle of inclination with respect to the axis of the valve body. The control characteristics expressed by the rotor rotation angle, pressure, and opening area of a rotation control valve using this rotor can be approximated to a desired characteristic curve as shown by the dotted line in FIG.

6 and 7 show other embodiments of the present invention.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view at right angles to the mounting direction of the rotation control valve, FIG. 2 shows a rotor with an oil groove arranged parallel to the axis of the valve body, and FIG. FIG. 4 is an axial cross-sectional view of a rotation control valve having the rotor shown in FIG. 4, and FIG. Figure 6 shows the control characteristics of the opening area and pressure with respect to the rotor rotation angle.
7 show another embodiment of the present invention. 1: Valve body 2: Rotor 2a: Rotor oil groove 3: Torsion bar 4: Supply hole 5: Ring-shaped groove 6.7: Pressure oil supply/discharge groove 11.12.13: Pressure oil inclined with respect to the axis Oil groove with control edge Fig. 1 N Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 11 - Loader rotation hexagon → Rotor rotation angle No. 6
Figure 7

Claims (3)

[Claims] (1) The input shaft and output shaft are connected on the same axis via a torsion bar, and the valve body consists of a rotor that rotates together with the input shaft and a valve body that is rotatably fitted to the rotor and rotates together with the output shaft. Equipped with a rotation control valve, the valve body is provided with grooves for supplying and discharging pressure oil from the hydraulic pump to the hydraulic cylinder for steering operation assistance, and the torsion bar is adjusted according to the load on the output shaft. A rotation control valve that controls the flow rate of pressure oil to a hydraulic cylinder in a power steering device that operates an output shaft system by controlling the opening amount of a discharge groove according to the relative rotational position of the valve body and rotor through twisting. A power steering device having a rotation control valve, characterized in that the center line of an oil groove provided in a rotor and the center line of a groove provided in a knob body are arranged to intersect with each other. . (2) In the power steering device according to claim (1), “the oil that controls the flow rate of pressure oil of the rotor constituting the rotation control valve that controls the flow rate of pressure oil to the hydraulic cylinder” A power steering device having a rotation control valve consisting of a rotor having an oil groove so that the center line of the groove is parallel to the axis. (3) In the power steering device according to claim (1), the valves constituting the rotation control valve that controls the flow rate of pressure oil to the hydraulic cylinder are parallel to the axis. A power steering bag device having a rotation control valve consisting of a valve body having a groove provided in the same manner.