JPH0413262Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a power steering device for a vehicle equipped with a hydraulic reaction force mechanism.

[Prior art]

One type of power steering system for a vehicle has a reaction force chamber to which a portion of hydraulic fluid discharged from a hydraulic pump is supplied through a fixed throttle, and a reaction force is generated toward the handle according to the oil pressure in the reaction force chamber. There is a power steering device for a vehicle that is equipped with a hydraulic reaction force mechanism that transmits force.

In this type of power steering device,
As shown in Publication No. 30659, an electromagnetic proportional control valve is provided in a second oil passage connecting the first oil passage between the fixed throttle and the reaction force chamber and the reservoir, and By increasing the applied hydraulic pressure in accordance with an increase in vehicle speed, a steering reaction force corresponding to the vehicle speed is applied to the driver.

[Problem that the invention attempts to solve]

The present invention is a vehicle power steering device equipped with a rotary valve type switching valve mechanism, which is different from the above-mentioned known power steering device, that is, integrated with a first shaft rotatably supported within a valve housing. a valve rotor that rotates integrally with the valve rotor; and a second shaft that is coaxially and connected to the shaft end of the first shaft so as to be rotatable relative to the shaft by a predetermined amount, and rotates integrally with the second shaft that rotates concentrically around the outer periphery of the valve rotor. A valve sleeve is arranged, a switching valve mechanism is provided between the valve sleeve and the valve rotor and is capable of switching the oil supply/drainage path to each oil chamber of the power cylinder, and a switching valve mechanism is inserted concentrically between the two shafts to In a vehicle power steering device including a torsion bar that connects both shafts and generates relative rotation between the valve rotor and the valve sleeve in accordance with steering torque, a steering reaction force is applied to a driver in accordance with vehicle speed. The purpose is to make sure that

[Means for solving problems]

In order to deal with this, the present invention provides a hydraulic reaction force mechanism of this type of vehicle power steering device with a cam groove provided on the outer periphery of the first shaft at the fitting portion of the two shafts, and a cam groove provided on the outer periphery of the first shaft. a plunger that is liquid-tightly and slidably assembled in a through hole provided in the second shaft in the radial direction, and a reaction force chamber that is provided in the back of the plunger within the through hole; , a first oil passage for applying a part of the hydraulic oil discharged from the hydraulic pump to the reaction force chamber through a fixed throttle; and a variable throttle valve that increases the amount of throttle in accordance with an increase in vehicle speed; It is constituted by an oil passage and a second oil passage connecting the reservoir.

[Functions and effects of the idea]

As a result, in the present invention, the hydraulic pressure applied to the reaction force chamber is increased as the vehicle speed increases, increasing the pressing force against the cam groove of the plunger, and increasing the braking force against the rotation of the first shaft as the vehicle speed increases. It can be increased accordingly. For this reason, it is possible to accurately apply a steering reaction force to the driver according to the vehicle speed, making it easier to operate the steering wheel lightly when stationary or at very low speeds, and to increase the steering force as the vehicle speeds up to medium or high speeds. can.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a power steering device according to the present invention. This power steering device is a rack and pinion type power steering device, and includes a switching valve mechanism A and a hydraulic reaction force mechanism B.

In this power steering device, an input shaft 13 and a pinion shaft 14 are coaxially and rotatably supported within a valve housing 11 and a gear box 12 that is fluid-tightly fixed to the valve housing 11. Both shafts 13 and 14 are connected to each other so as to be relatively rotatable by a predetermined amount, and are connected by a torsion bar 15. Further, reaction force chambers of the switching valve mechanism A and the hydraulic reaction force mechanism B are provided in the valve housing 11 .

The switching valve mechanism A is a conventionally known open center type rotary valve, and its main components include a valve rotor 21 that is integrally provided with the input shaft 13, and a valve sleeve 22 that is arranged concentrically around the outer circumference of the valve rotor 21. The valve rotor 21 has circular arc grooves 21a that are evenly formed at eight locations on the outer periphery of the input shaft 13 and extend in the axial direction, and communicate with the inner hole 21b by extending from the bottom of every other circular groove 21a toward the axis. A hole 21c and an inner hole 21 extending from the outer periphery to the axis at a portion above the valve sleeve 22.
It is provided with a communication hole 21d that reaches b. On the other hand, the valve sleeve 22 is integrally connected at its lower end to the upper end of the pinion shaft 14 via a connecting pin 23. In this valve sleeve 22, switching grooves 22a are formed evenly at eight locations on the inner circumference and extend in the axial direction, and communication holes 2 are evenly formed at four locations between each switching groove 22a.
2b, and every other half of each switching groove 22a is provided with an annular groove 2 at the upper end of the outer periphery of the valve sleeve 22.
2c, and the remaining half communicate with the lower end annular groove 22d, and the communication hole 22b communicates with the central annular groove 22e. In this valve sleeve 22, the upper end annular groove 22c passes through the oil supply/drainage path P1 and connects to the right side oil chamber R1 of the power cylinder C.
The lower end annular groove 22d communicates with the left oil chamber R2 through the oil supply/discharge path P2, and the central annular groove 22e communicates with the hydraulic pump 31 through the oil supply/discharge path P3. Note that the upper oil chamber R3 in which the communication hole 21d opens communicates with the reservoir 32 through the discharge oil path P4.

As a result, in the power steering device, both shafts 1 can be controlled by operating the steering handle W.
When relative rotation occurs between 3 and 14, the supply oil path P3
The hydraulic oil supplied through the valve sleeve 22
The oil is supplied to either one of the oil chambers R1 or R2 of the power cylinder C through the central annular groove 22e, the switching groove 22a, one of the annular grooves 22c or 22d, and the oil supply/discharge path P1 or P2. At the same time, the hydraulic oil in either the other oil chamber R2 or R1 is transferred to the other oil supply/discharge passage P2 or P1, the annular groove 22d or 22c, the switching groove 22a, the communication hole 21c, the inner hole 21b, the communication hole 2d, and the discharge. It flows back to the reservoir 32 via the oil path P4. As a result,
The steering force when turning the steering wheel W to the right or to the left is assisted.

In this power steering device, as shown in FIGS. 1 and 2, there are four through holes 14 that penetrate in the upper part of the pinion shaft 14 in the radial direction.
a, and a plunger 33 constituting the hydraulic reaction force mechanism B is fitted into each through hole 14a so as to be slidable in the radial direction. Each plunger 33 faces each cam groove 13a provided on the outer periphery of the lower end of the input shaft 13, and has a reaction force chamber R at the back thereof.
4 is formed. As a result, each plunger 3
3 is pressed against each cam groove 13a of the input shaft 13 by the hydraulic pressure applied to each reaction force chamber R4,
The pinion shaft 14 according to the oil pressure in the reaction force chamber R4.
The rotational force of the input shaft 13 against the input shaft 13 is braked. Each reaction force chamber R4 has a first oil passage P5 that bypasses the supply oil passage P3, and a reserve 32 for the first oil passage P5.
The second oil passage P6 is connected to the second oil passage P6. In these oil passages, a fixed throttle 3 is installed in the first oil passage P5.
4 is interposed therein, and an electromagnetic control valve 35 having a variable throttle portion is interposed in the second oil passage P6. In the power steering system, the electromagnetic control valve 35 is controlled by a controller 36b that operates in response to a vehicle speed signal from a vehicle speed sensor 36a, and gradually increases its throttle amount as the vehicle speed increases.

In the power steering system configured in this way, the electromagnetic control valve 35 is
is opened to the maximum, and the amount of throttle increases gradually as the vehicle speed increases. Therefore, the hydraulic pressure applied to each reaction force chamber R4 is small when the vehicle is stopped and at extremely low speed, and gradually increases as the vehicle speed increases, thereby increasing the pressing force of each plunger 33 against each cam groove 13a of the input shaft 13. is increased according to the rise in the above oil pressure. Therefore, each plunger 33 can brake the rotation of the input shaft 13 according to the increase in vehicle speed, and can apply a steering reaction force to the driver according to the vehicle speed. It is possible to make the steering wheel operation lighter, and to make the steering wheel operation heavier as the speed increases.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of a power steering device according to an embodiment of the present invention, and FIG. 2 is a sectional view taken in the direction of the arrow in FIG. 1. Explanation of symbols, A...Switching valve mechanism, B...Hydraulic reaction force mechanism, 13...Input shaft, 14...
Pinion shaft, 21...Valve rotor, 22
... Valve sleeve, 33 ... Plunger, 34
...Fixed throttle, 35...Solenoid control valve, P5...First oil passage, P6...Second oil passage, R4...Reaction force chamber.

Claims (1)

[Scope of utility model registration request] a first rotatably supported within the valve housing;
a valve rotor that rotates integrally with the shaft;
a valve sleeve that rotates integrally with a second shaft coaxially and connected to the shaft end of the shaft so as to be relatively rotatable by a predetermined amount, and is arranged concentrically around the outer periphery of the valve rotor; A switching valve mechanism is provided between the valve rotors and is capable of switching the oil supply/drainage path to each oil chamber of the power cylinder, and a switching valve mechanism is inserted concentrically between the two shafts to connect the two shafts, and the switching valve mechanism can switch the oil supply/drainage path to each oil chamber of the power cylinder. A vehicle power steering device comprising: a torsion bar that generates relative rotation between a valve rotor and a valve sleeve; and a hydraulic reaction force mechanism that brakes rotation of the first shaft and transmits a reaction force to a handle side. A reaction force mechanism is provided in a liquid-tight manner in a cam groove provided on the outer periphery of the first shaft at the fitting portion of the two shafts, and a through hole provided in the radial direction in the second shaft opposite to the cam groove. and a plunger assembled so as to be slidable in the radial direction, a reaction force chamber provided at the back of the plunger in the through hole, and a part of the hydraulic fluid discharged from the hydraulic pump passed through a fixed throttle to absorb the reaction force. A first oil passage provided to the chamber, and a second oil passage that connects the first oil passage and the reservoir and includes a variable throttle valve that increases the amount of throttle according to an increase in vehicle speed. Characteristic power steering device for vehicles.