JPS61278469A - Power steering device - Google Patents

Abstract

PURPOSE:To aim at simplification and miniaturization in a device structure, by forming a spool, controlling a discharge flow rate out of a pump, in a pump body, while installing a variable throttle part, controlling a position of the spool by differential pressure, in the said body. CONSTITUTION:A flow control valve V consisting of a variable throttle part (f) and a flow control part (s) should be solidly assembled in a body 11 of a pump P, while the body 11 is made up of installing an inflow hole 12 to be interconnected to the discharge side of the pump P, a return hole 13 returning a hydraulic fluid to the inside of the pump P and feed hole 16 to be interconnected to a control valve 15 of a power cylinder 14. In addition, a partition wall 17 is installed in a passage process between the inflow hole and the feed hole 16, forming a discharge hole 18 herein, and a spool 19 of the flow control part (s) is installed at the upstream side of the said hole 18, while a sliding shaft 20 of the variable throttle part (f) making a proportional solenoid 25 a driving source is installed at the downstream side, respectively. This proportional solenoid 25 is energized with a continuous rating current and controlled by a controller C on the basis of a car speed v and a pump revolving speed N.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a power steering device that controls steering force according to vehicle speed and pump rotation speed (prior art) The conventional device shown in FIG. is a first flow control valve a and a second flow control valve a in the flow path connecting the pump P and the power cylinder 1.
A flow control valve is provided.

The first flow control valve a is integrated with the pump P, and controls the discharge amount of the pump P according to the differential pressure before and after the fixed throttle 2, and also sets the number of rotations of the pump P. In other words, when the discharge amount of the pump P exceeds the set flow rate, as shown in FIG. 5, the discharge amount is kept constant.

Further, the second flow control valve is equipped with a variable throttle 3 that controls the opening degree according to the vehicle speed of the vehicle, and as shown in FIG.
As the vehicle speed increases, the opening degree of the variable throttle 3 is reduced to reduce the flow rate supplied to the power cylinder 1.

In other words, this conventional device controls the opening area of the variable throttle 3 of the second flow rate control valve depending only on the vehicle speed when the discharge amount of the pump P exceeds the set flow rate.

(Problems to be Solved by the Present Invention) In the conventional device as described above, the first flow rate control valve a and the second flow rate control valve a must be provided separately, which increases the complexity of the structure. At the same time, there was a problem in that the overall size of the device also increased.

In addition, in this device, when the pump P reaches a predetermined rotation speed or higher, the supply flow rate is controlled depending only on the vehicle speed. When the engine speed increases as in the case of
There was a problem that the above-mentioned supply flow rate increased, making accurate control impossible.

The object of the present invention is to provide a device that integrates flow control valves into one and controls the flow rate depending on both vehicle speed and rotational speed.

(Means for Solving Problems) In order to achieve the above object, the present invention includes a spool for controlling the discharge flow rate from the pump inside the body, a discharge hole is formed on the downstream side of the spool, and , a sliding shaft is provided downstream of the discharge hole, the amount of movement of which is controlled according to the amount of energization to the proportional solenoid, and the actual opening surface of the discharge hole is controlled according to the position of the movement;
The spool stops at a position where the front pressure and back pressure of the discharge hole are balanced, and the flow rate is specified at that stop position, while the proportional solenoid adjusts its energization amount according to the vehicle speed and pump rotation speed. It is configured to control.

(Operation of the present invention) Since the present invention is configured as described above, the opening area of the discharge hole is controlled according to the vehicle speed and the pump rotation speed, and the opening area of the discharge hole is controlled according to the controlled opening area of the discharge hole. , the supply flow rate is controlled.

(Effects of the Present Invention) According to the device of the present invention, only one flow control valve is required, so the configuration is simplified and the entire device is downsized as compared to the conventional device.

In addition, since this flow control valve is controlled depending on both the vehicle speed and the pump rotation speed, for example, even when driving at low speeds such as when going up the hill, and even when the engine rotation speed, that is, the pump rotation speed is high, The supply flow rate does not increase beyond a predetermined flow rate, therefore, depending on the driving conditions of the vehicle,
Accurate control becomes possible.

(Embodiment of the present invention) The embodiment shown in FIGS. 1 to 3 is a body 1 of a pump P.
1, a flow rate control valve V is integrated into the flow rate control valve V, and this flow rate control valve V is composed of a variable throttle part f and a flow rate control part S, as is clear from FIG.

The variable throttle part g is connected to a controller c5 that outputs a signal according to the vehicle speed and the pump rotation speed.

The throttle opening degree of the variable throttle section f is controlled depending on the vehicle speed and the pump rotation speed.

A pressure difference is generated before and after the variable throttle section f depending on the opening degree of the variable throttle section f, and the front pressure and the back pressure are made to act on the flow rate control section S.

The specific structure of the flow control valve V thus constructed is as shown in FIG.

That is, the body 11 has an inflow hole 12 that communicates with the discharge side of the pump P, a return hole 13 that returns hydraulic oil to the inside of the pump P, and a supply hole 1B that communicates with the control valve 15 of the power cylinder 14. and is formed.

A partition wall 1 is provided in the flow path between the inflow hole 12 and the supply hole 1B.
7, a discharge hole 18 is formed in this partition wall 17, a spool 19 is provided on the upstream side of this discharge hole 18, and a sliding shaft 20 is provided on the downstream side.

The spool 19 has one end facing a chamber 21 communicating with the inflow hole 12 and the other end facing a chamber 22 communicating with the supply hole 1B, and a spring 23 is interposed in the chamber 22 communicating with the supply hole 1B. The spool 18 is normally kept at the normal position shown in the figure.

When the spool 19 is in the normal position shown, the land portion 24 causes the chamber 21. ! ; Communication with the return hole 13 is cut off, but when the spool 18 moves against the spring 23 and the land portion 24 is located outside the opening edge of the return hole 13, the opening degree of the return hole 13 changes. Accordingly, the flow flows out from the inlet hole 12 to the return hole 13.

Further, the sliding shaft 20 has its tip opposed to the discharge hole 18, and is inserted into a proportional solenoid 25, and moves according to the amount of current applied to the proportional solenoid 25, and at the moving position, slides. Shaft 20 and discharge hole 1
He is trying to control the facing distance with respect to B, that is, the substantial opening degree of the discharge hole 18. The proportional solenoid 25 is connected to the controller C, and
The amount of energization is controlled according to a signal depending on the vehicle speed and engine rotation speed (pump rotation speed) of the vehicle.

In this specific example, the spool 19 constitutes the main element of the above-mentioned flow rate control section S, and the discharge hole 1B and the sliding shaft 20
These constitute the variable aperture section f.

Thus, a signal dependent on both the vehicle speed and the engine speed is output from the controller C, and the amount of current applied to the proportional solenoid 25 is controlled in accordance with the output signal.

Therefore, the sliding shaft 20 specifies the moving position depending on the amount of current supplied to the proportional solenoid 25, in other words, depending on the vehicle speed and engine rotation speed.

When the moving position of the sliding shaft 20 is specified in this way,
The opposing interval between the sliding shaft 20 and the discharge hole 18 at that time is specified, and the opening degree of the discharge hole 18 is controlled. The narrower the facing interval, the smaller the opening degree of the discharge holes 18, and conversely, the wider the facing interval, the larger the opening degree.

Now, when the hydraulic oil of the pump P flows in from the inflow hole 12,
This hydraulic oil is supplied to the power cylinder 14 via the chamber 21 → discharge hole 18 → supply hole 16 → control valve 15. When the hydraulic oil flows into the discharge hole 18 in this manner, a differential pressure is generated before and after the hydraulic oil, and the front pressure acts on the chamber 21 and the back pressure acts on the chamber 23.

Therefore, if the pressure difference before and after the discharge hole 18 becomes large, the pressure difference will act on both ends of the pool 19, but when the spool 19 is in the middle, the spool 19 will move while bending the spring 23, and the above-mentioned repressurization will occur. Maintain a balanced position.

At this balance position, the opening degree of the return hole 13 is controlled and the return flow rate is specified, so that the flow rate flowing out from the supply hole 16 is controlled.

Furthermore, if the vehicle speed signal and engine rotation speed signal input to the proportional solenoid 25 change, the amount of electricity supplied to the proportional solenoid 25 changes in accordance with the signals, changing the moving position of the sliding shaft 20 and opening the discharge hole 18. Control opening degree.

Therefore, the pressure difference before and after the discharge hole 18 changes depending on the opening degree, so the spool 1θ moves according to the pressure difference, and the supply flow rate is controlled at the moving position.

As described above, in this embodiment, the opening degree of the discharge hole 18 is controlled depending on the vehicle speed and the engine rotation speed, and the supply flow rate is controlled according to the opening degree of the discharge hole 18. Therefore, for example, even under running conditions where the engine speed is low and the engine rotational speed increases, such as when climbing a hill, the flow rate supplied to the power cylinder 14 will not become too large, and accurate control will be possible.

In other words, in this embodiment, as shown in FIG. 3, the flow rate supplied to the power cylinder 14 is always controlled depending on the vehicle speed and engine speed, so that control suitable for the running conditions of the vehicle can be performed. It becomes possible.

[Brief explanation of drawings]

Drawings 1 to 3 show examples of this invention.
Figure 1 is a circuit diagram, Figure 2 is a cross-sectional view of the main parts, Figure 3 is a characteristic diagram showing the relationship between vehicle speed, pump rotational speed, and flow rate supplied to the power cylinder, and Figures 4 to 6 are Figure 4 shows a circuit diagram, Figure 5 shows a characteristic diagram showing the relationship between pump rotation speed and pump discharge amount, and Figure 6 shows the relationship between vehicle speed and flow rate supplied to the power cylinder. FIG. P...Pump, 11...Body, ■...Flow rate control valve, 18...Discharge hole, 18...Spool, 20...
...Sliding shaft, 25...Proportional solenoid.

Claims (1)

[Claims] A spool that controls the discharge flow rate from the pump is installed in the body, and a discharge hole is formed on the downstream side of this spool.Furthermore, downstream of this discharge hole, the amount of movement is controlled according to the amount of electricity applied to the proportional solenoid. In addition, the spool is provided with a sliding shaft that controls the substantial opening area of the discharge hole according to its movement position, and the spool stops at a position where the front pressure and rear pressure of the discharge hole are balanced. The power steering device is configured to specify the flow rate based on the position, and control the amount of current supplied to the proportional solenoid according to the vehicle speed and the pump rotation speed.