JPH0624947B2 - Hydraulic reaction force control device for power steering device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic reaction force control device that presses an input shaft of a power steering device with hydraulic pressure at high speed to obtain rigidity.

(Prior Art) FIGS. 4 and 5 show a hydraulic reaction force control system of a conventional power steering system. The pressure oil from the oil pump 1 is guided to the import 2a of the reaction pressure control valve 2. 3 is a main spool of the reaction pressure control valve 2 and 4 is a sub spool. The sub spool 4 has a reaction chamber side port 10 and a return outlet 2.
A fixed throttle 4a connecting b is formed, and the main spool 3
The relative displacement between the auxiliary spool 4 and the auxiliary spool 4 prevents the reaction force pressure from rising due to the pressure oil leaking from the gap between the spools when the variable throttle 5 on the reaction force chamber side is closed. The pressure oil from the oil pump 1 is guided to the reaction force chamber 8 formed on the pinion shaft 7 on the outer periphery of the input shaft 6, pressurizes the plunger 9 in the reaction force chamber 8 and causes the concave groove 6a on the outer periphery of the input shaft 6 to be formed. It is designed to be pressed to obtain steering reaction force.

However, in such a conventional hydraulic reaction force control device, the variable throttle 5 is closed to cut the reaction force pressure when the vehicle is stopped or at a low speed. If it is installed apart from the valve, the pressure Pf in the reaction force chamber may differ due to the length of the return circuit and the difference in the line resistance.
Since but not always made the pressure Pr ₂ greater than made structure on the input shaft side, Pr ₂ is when greater than Pf is out beam outwardly plunger produces a gap between the groove 6a of the input shaft,
During steering, the plunger comes into contact with the reaction force chamber wall 8a to cause a catch, and when the reaction force chamber side variable throttle is opened, the plunger collides with the input shaft, causing abnormal noise and smooth steering force. I couldn't get a change. Further, when the oil noise increases and the viscosity of the hydraulic oil decreases, there is a problem that the amount of leakage from the fixed throttle 4a increases and the reaction force pressure characteristic changes.

(Objective) The present invention was made by focusing on the above-mentioned conventional problems,
An object of the present invention is to eliminate the conventional drawback by eliminating the fixed throttle formed on the auxiliary spool of the conventional reaction force control valve and providing the fixed throttle on the pinion shaft in the reaction force chamber.

(Structure) In order to achieve the above object, the present invention fixes the other end of the torsion bar, one end of which is fixed to the input shaft connected to the handle, to the output shaft connected to the steering wheel, and the outer peripheral groove of the central part of the input shaft. And the rotary valve groove engaged with the output shaft controls the hydraulic pressure from the pump to control the power assisting force. Plural radial through holes are provided in a part of the output shaft and the plungers are provided. A power steering device in which the outside of the plunger is used as a hydraulic reaction chamber by allowing the tip of the plunger to fit into the groove of the input shaft tip and applying the hydraulic pressure from the pump to the outside of the plunger. In the hydraulic reaction force control device, the output shaft is further provided with a through hole in the radial direction to form a fixed throttle, and the outside of the plunger and the tip of the plunger are communicated by the fixed throttle. It is a thing.

Hereinafter, a specific description will be given based on the embodiment shown in FIGS. 1 to 3. Reference numeral 21 is a main valve, 22 is a reaction pressure control valve, and pressure oil from the oil pump flows into the import 23a of the valve housing 22, operates the solenoid 24 according to the vehicle speed, and moves relative to the main spool 25 and the spool 26. Port 27 to the power steering side due to displacement
Alternatively, it is selectively guided to the port 28 on the reaction force chamber side. Reference numeral 29 is an input shaft. Four radial reaction force chambers 31 are formed on the outer circumference of the pinion shaft 30, and a plunger 32 is slidably fitted to the pinion shaft 30. The pinion shaft 30 is made of a synthetic resin having a large linear expansion coefficient. The orifice 33 is provided, and the orifice 33 has a small hole 33.
A fixed diaphragm made of a is formed.

The torsion bar 36 has one end fixed to the input shaft 29 and the other end fixed to the pinion shaft 30, and the torsional displacement of the torsion bar 36 causes relative displacement between the rotary valve groove 37 and the input shaft center outer peripheral groove 3. The main valve 21 operates.

Next, the operation will be described. When stopped and at low speed, the solenoid 24 causes the auxiliary spool 26 to be pulled to the left as shown in FIG. 3, the variable throttle 34 on the reaction force chamber side is closed, and only the variable throttle 35 on the main valve side is open. ,
Since all the pressure oil from the oil pump 1 flows to the main valve 21 side through the port 27, the reaction pressure does not increase and a light steering force can be obtained. At this time, since the oil is not supplied into the reaction force chamber 31, the return pressure Pr ₂ acts on the surface 32a of the input shaft of the plunger 32, and the reaction pressure Pf lower than Pr ₂ acts on the reaction force chamber side 32b. Works. Then, the oil of the return pressure Pr ₂ flows into the reaction force chamber side through the small hole 33a of the orifice 33, so that the hydraulic pressures of the both surfaces 32a and 32b of the plunger 32 are balanced and the plunger 32 moves outside the reaction force chamber 31. There is no displacement to one side. Therefore, the auxiliary spool 26 is moved to the right by the solenoid 24 at high speed, and the variable throttle 3 on the reaction force chamber side is moved.
When 4 is opened and the pressure oil acts on the rear surface of the plunger 32, the reaction torque changes smoothly.

If the orifice 33 is made of a material such as a synthetic resin having a large linear expansion coefficient, the diameter of the small hole 33a becomes small at a high temperature, so that the amount of oil leaking from the small hole 33a will decrease even if the viscosity of the oil decreases. Small changes in performance such as reaction force characteristics can be suppressed.

(Effect) According to the present invention, the other end of the torsion bar having one end fixed to the input shaft connected to the handle is fixed to the output shaft connected to the steering wheel, and is engaged with the outer peripheral groove of the input shaft central portion and the output shaft. The hydraulic pressure from the pump is controlled by the relative displacement with the rotary valve groove, and a plurality of radial through holes are provided in a part of the output shaft to slidably fit the plungers. Insert the valve, insert the plunger tip into the input shaft tip groove, and apply the hydraulic pressure from the pump to the outside of the plunger to make the outside of the plunger a hydraulic reaction chamber. In this case, since the output shaft is further provided with a radial through hole to form a fixed throttle and the outside of the plunger and the tip of the plunger are communicated by the fixed throttle, the plunger is pushed outward. And the reaction chamber is scratched on the side wall Preparative can be reliably prevented, since no plunger when the reaction force pressure is applied collides with the input shaft, without occurrence of abnormal noise, it is possible to smoothly perform the change of the reaction torque.

[Brief description of drawings]

1 is a front sectional view of an embodiment of the present invention, FIG. 2 is a front sectional view of a reaction force chamber portion of FIG. 1, FIG. 3 is a front sectional view of a reaction force control valve of FIG. 1, and FIG. FIG. 5 is a plan sectional view of a conventional reaction force chamber portion, and FIG. 5 is a front sectional view of a conventional reaction force control valve. 21 ... Main valve 22 ... Reaction force control valve 23 ... Valve housing 23a ... Import 24 ... Solenoid 25 ... Main spool 26 ... Sub spool 27,28 ... Port 29 ... Input shaft 30 ... Pinion shaft 31 ... Reaction chamber 32 ... Plunger 33 ... Orifice 33a ... Small hole 34 ... Variable throttle on reaction chamber side 35 ... Variable throttle on main valve side

Claims (2)

[Claims] 1. A rotary valve in which the other end of a torsion bar, one end of which is fixed to an input shaft connected to a handle, is fixed to an output shaft connected to a steering wheel, and which is engaged with an outer peripheral groove of a central portion of the input shaft and the output shaft. The hydraulic pressure from the pump is controlled by the relative displacement with the groove to control the power assisting force. Plural radial through holes are provided in a part of the output shaft, and the plungers are slidably inserted in each A hydraulic reaction force control device for a power steering system in which the plunger tip is fitted into the input shaft tip groove and the hydraulic pressure from the pump is applied to the outside of the plunger to make the outside of the plunger a hydraulic reaction chamber. A hydraulic reaction force control of a power steering device characterized in that a fixed throttle is formed by further providing a radial through hole on the output shaft, and the outside of the plunger and the tip of the plunger are communicated by the fixed throttle. apparatus. 2. A hydraulic reaction force control device for a power steering apparatus according to claim 1, wherein the fixed throttle is made of synthetic resin having a large linear expansion coefficient.