JPS58152664A - Flow rate controller for power steering - Google Patents

Abstract

PURPOSE:To prevent variations in the flow rate due to a steering load in a high rotation range by forming a variable orifice for controlling flow rate with a through hole of a piston body and a drooping pin to apply a downstream pressure thereof on a spool for controlling the escape of an access flow rate. CONSTITUTION:When a steering load is applied on a supply port 3, a downstream pressure of a variable orifice 21, namely the pressure of a rear pressure chamber 9 rises to put back a spool 7 to reduce the opening of a bypass port 4 thereby raising the pressure corresponding to the load. Consequently, a piston body 8 displaces against a spring 15 to maintain the same opening of the variable orifice 21 defined by a head 17A of a drooping pin 17 and a through hole 20 and prevents the increase in the supply flow rate. This can reduce the supply flow rate at a high rotation range of a pump regardless of variations in the load of a power steering to improve the operational stability while enabling direct application of a pressure at a pump port 2 on the spool for controlling the bypass flow rate to elevate the response thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to working fluid flow-control equipment in power steering.

In power steering, which reduces the burden on the driver by hydraulically assisting steering operations in heavy-duty vehicles, the hydraulic assist force is reduced at high speeds because the turning resistance of the skewer shaft decreases significantly at high speeds. Many vehicles are designed to improve maneuverability.

Since the pump that serves as the hydraulic pressure source is driven in synchronization with the engine rotation, the amount of discharge flow increases in the rotation range, resulting in a large amount of hydraulic oil being supplied to the hydraulic actuator of the power steering, but this can be prevented. A flow iron control device is provided with a flow control valve to control the flow rate, and a drooping bin type flow iron control device that reduces the supply flow rate as the rotational speed increases.

However, in this case, when the power steering load increases, the spool of the flow control valve is displaced in response to this load pressure, and the position of the drooping bin changes, so the supply flow rate may fluctuate depending on the load pressure. there were.

In order to deal with such problems, Japanese Patent Application Laid-Open No. 56-1041
In No. 86, the control spool that acts as a drooping bin is connected to the flow control valve's spool! - A method has been proposed in which the operation of the flow control valve does not affect the opening degree of the variable orifice by the control spool.

However, in this case, the restriction passage that provides a pressure difference between the front and rear of the control spool is installed separately from the i-control spool, which complicates the structure for guiding this pressure difference, and the spool of the flow control valve Since the pressure downstream of the restriction passage acts on the spool, the response of the spool to fluctuations in the flow rate of the pump boat is low, and there is a problem in that the control of the bypass flow rate, in other words, the feedback control characteristics of the supply flow rate deteriorates.

The present invention was proposed in order to solve such problems, and a piston body is freely slidably interposed between a pump boat from a hydraulic pump and a supply boat to a hydraulic actuator. A drooping bottle integrated with the spool is inserted into the through hole of the body to provide a variable flow control orifice, and the pressure upstream of the piston body and the pressure downstream of the variable orifice are adjusted to release the surplus flow to IIJ ml of the spool. Power steering flow control I with a simple structure and high control accuracy can prevent flow fluctuations due to the 9 steering directions in the rotation range by acting on both ends.
It provides equipment.

Embodiments of the present invention will be described below based on the drawings.

In the embodiment shown in FIG. 1, a body 1 of the control device includes a pump boat 2 connected to the hydraulic pump discharge side, a supply boat 3 connected to the hydraulic actuator side of the power steering via a switching valve (not shown), and a surplus A bypass boat 4 for returning the flow rate to the reservoir side is formed, and these boats open into the spool holes 5 of the body 1, respectively.

In the spool hole 5, a spool 7 that serves as a flow control valve to release excess oil and a piston body 8 that makes the flow path to the supply boat 3 variable are provided so as to be freely slidable. .

The spool 7 is pressed until it engages with the stopper 14 by the spring 10 of the back pressure chamber 9 to which the back pressure of the variable throttle is introduced, thereby closing the bypass port 4. However, when the front pressure of the throttle applied to the left end of the spool increases. , the spool 7 is pushed back to open the bypass port 4, allowing some of the hydraulic oil to escape to the reservoir side.

On the other hand, the piston body 8 is slidably inserted into a sleeve (cylindrical portion) 12 formed on the plug 13 of the supply boat 3 fitted into the spool hole 5 .

The piston body 8 is formed into a cylindrical shape, and the distance between them is ! ! A through hole 20 is provided in the center of the pump 11, and the pump 11 is pushed toward the pump boat by a spring 15 until it comes into contact with a stopper 14 secured to a retaining ring 16.

A drooping bin 17 whose tip end is a head 17A is integrally protruded from the spool 7, and this drooping bin 17 enters and exits a through hole 20 connecting the pump boat 3 and the inside of the sleeve v19. , constitutes a variable orifice (variable aperture) 21 that changes the opening degree of the orifice.

Note that a triangular notch groove 23 is formed in the portion of the through hole 20 to smoothly control the elevation of the area change of the variable orifice 21.

Note that the passage 22 guides the downstream pressure of the variable orifice 21 to the back pressure chamber 9 of the spool 7.

Next, the operation will be explained with reference to FIG. When the flow rate sent to the bob boat 2 is low, the hydraulic oil flows through the through hole 2.
Gold flows through the internal chamber 19 from 0 to the supply port 3.

When the supply flow rate of the pump boat 2 increases and the differential pressure generated in the through hole 20 increases beyond a certain value, the spool 7
moves backward against the spring 10 and begins to open the bypass port 4.

For this reason, a part of the hydraulic oil in the pump boat 2 is bypassed to the reservoir side, and the front and rear pressure of the through hole 20 is kept almost constant.

Therefore, the flow 11 to the supply port 3 is a substantially constant flow depending on the opening degree of the through hole 20 even if the pump rotation speed changes.

By the way, at this point, the piston body 8 does not move because the pressure difference between the front and back due to the through hole 20 does not overcome the force of the spring 15, and the opening degree of the through hole 20 does not change.

When the pump rotational speed further increases and the flow rate increases, the spool 7 is further displaced while bending the spring 10, and eventually the head 17A of the drooping bin 17
is inserted into the through hole 20.

As a result, the opening degree of the variable orifice 21 is rapidly reduced, and the flow rate flowing into the supply boat 3 is reduced.

Thereafter, even if the spool 7 is displaced, the effective area of the through hole 20 remains approximately constant, so the supply flow rate remains approximately constant at the minimum i.

Incidentally, the piston body 8 moves to a position where the longitudinal pressure of the variable orifice 21 and the fluid force of the passing flow are balanced with the acting force of the spring 15, but when the load on the hydraulic actuator side is small, the piston body 8 is displaced. Instead, it is held by the orifice spring 15 at a position where it abuts against the stopper 14.

On the other hand, when a steering load is applied to the supply boat 3 side, the pressure downstream of the variable orifice 21 increases in accordance with the load. Along with this, the pressure in the rear pressure chamber 9 is increased by 1, and the spool 7 is returned.
The opening degree of the bypass boat 4 is reduced and the pressure of the pump boat 2 is increased in accordance with the load, but this causes the piston body 8 to move against the spring 1 due to the differential pressure across it and the fluid force.
5 is displaced while being compressed, the opening degree of the variable orifice 21 is ultimately kept the same, and the supply flow rate can be prevented from increasing as in the conventional drooping bin system.

In other words, due to the displacement of the spool 7, the drooping bin 17
When the oil is drawn out, the flow rate passing through the variable orifice 21 tends to increase, but at this time, the fluid force of this increased amount of hydraulic oil acts on the piston body 8 in the same direction as the drooping bottle 17. In addition, the increase in differential pressure due to the relative increase in flow rate comes into play, and as the load pressure increases, the piston body 8 eventually displaces in the same direction as the spool 7, which prevents the relative relationship from changing and prevents stray running. Even if the steering is carried out inside the vessel, the increase in flow age can be suppressed as shown in Figure 2.

The reason why the area of the flat part in FIG. 2 expands due to the load pressure is that the flow control of the supply flow rate by the spool 7 gradually increases as the acting force of the spring 10 changes with the displacement of the spool 7. This is due to the fact that the starting point of the piston body 8 following the spool 7 is different.

The followability of the piston body 8 with respect to the spool 7 can be freely set by changing the spring constant of the spring 15 or 1-o, and the shape of the drooping pin 17 and the shape of the notch groove 23 can be set freely. By changing it, the droop characteristic when the load pressure is applied can be changed stepwise or continuously.

By the way, since the pump boat pressure (Fl pressure) directly acts on the spool 7 for differential pressure control, the responsiveness to this pressure fluctuation is extremely good, and accurate pressure feedback control can be performed.

As described above, according to the present invention, regardless of power steering load fluctuations, the supply flow rate in the pump high rotation range is reduced to improve maneuverability, while the spool that controls the bypass flow , the pressure of the pump boat is applied directly, which improves responsiveness.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a first embodiment of the present invention. FIG. 2 is a flow characteristic diagram of the present invention. 1...Body, 2...Pump boat, 3...Supply boat, 4...Bypass port, 7...Spool,
8...Bis 1~n body, 10. ．． 15... Spring, 12... Sleeve, 14... Stopper, 17...
・1 Nilbing pin, 2°...Through hole, 21...Variable orifice. Patent Applicant Kayaba Kogyo Co., Ltd. Figure 2 Rotary Soft (xloo rρm) Procedural Amendment June 14, 1981 Commissioner of the Patent Office Shima 1) Haruki Tono1, Indication of the case 1.・. 1985 Moshohoho No. 34659 2, Name of the invention 1 # Arm steering flow rate control device 3, Relationship with the amended case Patent applicant address: 2-chome Hamamatsucho, Minato-ku, Tokyo @ 4-Qiao 1 World Trade Center Pill Name (092) Senba Kogyo Co., Ltd. 4, Agent address: 3rd floor 6, Za 8-10 Building, 8-10-8 Chinza, Chuo-ku, Tokyo 104 "Detailed explanation" and "Simple drawing (1)
Insert the following sentence in the darkness of page 9, line 15 and line 16 of the specification. [Next, the embodiment shown in FIG.
is formed to prevent vibration of the piston body 8 and suppress flow rate fluctuations. The men/da 1130 connects the outer periphery of the piston body 8 and the bladder 13.
The piston body 8 is formed between the inner periphery of the piston body 8 and communicates with the inner diameter 19 through a nine orifice 31. When the piston body 8 moves, hydraulic oil enters the armpit chamber 30, and by squeezing this through the orifice 31 and imparting resistance, the vibration of the piston body 8 is suppressed. ”
(2) Similarly, on page 10, line 4, “......tI
t]1i1t+:! It is a sex diagram. "...
. . . The flow characteristic diagram, FIG. 3, is a sectional view of another embodiment. ” he corrected. (3) Among the drawings attached to the specification, Figure 3 will be added as an attached document.

Claims (1)

[Claims] The oil discharged from the hydraulic pump is sent from the pump boat to the supply boat that communicates with the hydraulic actuator via the throttle part, and the excess flow is returned via the spool that opens and closes the bypass boat in response to the above-mentioned back and forth pressure. In this power steering flow control system, a piston body is slidably interposed between a pump boat and a supply boat, and a drooping bottle integrated with the spool is inserted into a through hole provided in the piston body. A power steering link flow rate 11JIIll characterized in that the pressure of the pump boat and the downstream pressure of the variable orifice are guided to both ends of the spool by inserting a variable orifice to form a variable orifice.
If.