CA1263414A

CA1263414A - Restriction valve device for hydraulic pressure fluids in vehicle shock absorbing mechanisms

Info

Publication number: CA1263414A
Application number: CA000510950A
Authority: CA
Inventors: Magnus Lizell
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-06-05
Filing date: 1986-06-05
Publication date: 1989-11-28
Also published as: EP0268608B1; US5143186A; US5337863A; DE3788853D1; EP0268608A1; EP0268608A4; US4923038A; AU7237987A; AU599973B2; US5025899A; WO1987007565A1; DE3788853T2

Abstract

Abstract of Disclosure A restriction valve device for hydraulic pressure fluids in vehicle shock absorbing mechanisms comprises a valve seat member with at least one main passage for the flow of said pressure fluid, said main passage being closable by means of a movable spring-biased valve body, and at least one auxiliary passage for the pressure fluid, said auxiliary passage being selectively closable by a closure element. To provide for a fast a reliable change or control of the functional characteristics of the damper, yet making same inexpensive and uncomplicated, the invention suggests that a closed variable space is confined between the valve seat member and the valve body, the auxiliary passage being connected to said space to provide, under the control of the closure ele-ment, for a variable pressure of said fluid onto said valve body against the force of the biasing spring so as to change the functional characteristics of the restric-tion valve device.

Description

12~3~1~

A RESTRICTION VALVE DEVICE FOR HYDRAULIC PRESSURE
FL~IDS IN VEHICLE SHOCK ABSORBING MECHANISMS.

Background of the Invention The present invention refers to a restriction valve device for hydraulic pressure fluids in vehicle shock absorbing mechanisms comprising a valve seat member with at least one main passage for the flow of said pressure fluid, said main passage being closable by means of a movable spring-biased valve body, and at least one auxiliary passage for the pressure fluid for applying pressure from the pressure fluid onto the valve body, the flow of pressure fluid through said auxiliary passage being controlled by a closure element.
Restriction valve devices of this kind are previously known. As far as shock absorbers for vehicles and the like are concerned it is often desirable that the damping action obtained be variable so that the shock absorber can be adapted as requested to various requirements. As is known, the damping action of hydrau-lic shock absorbers is obtained by intentionally rest-ricting the flow of the hydraulic liquid between various chambers to either side of a movable piston or the like by means of a restriction valve device. Most often a flow passage or a plurality of circumferentially spaced openings are closable by means of a valve body which is spring-biased towards a closed position. By varying the number of openings and/or their cross-sectional area, a flow resistance and hence a restricting action of desired, predetermined characteristics can be obtained.
Particularly when it comes to vehicle shock absorbers it is also desirable, however, that the damping action be controllable. Almost without any ex-ceptions this has been effected in prior art devices by ~'~

12~;3~

exposing when desired one or more further flow passages for the hydraulic fluid by means of some further valve body or action. Common to these prior art structures is, that they are very complicated and thus expensive and also that they are slow in their action. A vehicle shock absorber, however, should be capable of changing the restriction characteristics very fast, i e in a shorter time than 5 ms, and the arrangement employed should not be too power-consuming.
An example of a prior controllable restriction valve device is disclosed in JP A 57 173 629. According to said publication a solenoid-operated valve means is adapted to be pressed against the mouth of at least one of a plurality of hydraulic fluid flow passages through a piston. The flow area thus is reduced and the restric-tion action and hence the damping action increased.
Another example of a previously known adjustable restriction valve device is GB A 2 112 104. With the exception of the fact that the adjustment of the charac-teristics of the restriction valve device is obtained by angularly adjusting a member provided with flow passages so as to expose a greater or smaller number of flow passages, the basic operation in principle is the same as in the afore-mentioned Japanese publication. The restriction valve device of this British reference also utilizes electromagnetic actuation although not in connection with a real solenoid mechanism.
A further example of an adjustable restriction valve device in connection with the shock absorbers is EP A 0123365. This European publication discloses a double-acting hydraulic shock absorber having a rest-riction valve device comprising a control body which is also provided with a solenoid and adapted to effect, by " .

,1 .
' ~ ' , , ::.
.
, ~

,. .
. .
.. . .
, lZ63 ~

energizing the solenoid, an axial displacement of a clo-sure means in order to expose at least one further flow passage for the hydraulic fluid. As a result, greater flow rates through the restriction valve device are pro-vided for and hence a reduced or smaller damping action.

SUMMARY OF THE INVENTION

The main object of the present invention is to provide a restriction valve device of the afore-men-tioned kind which is much simpler in design, less expen-sive, and which acts quicker than the prior art devices, the restriction valve device of the present invention based on a principle that is different from the approach used in the prior art, namely the arrangement of the pre-sent invention does not increase the hydraulic liquid flow so as to decrease the restricting action as in the prior art but instead operates to change the restricting action by causing the pressure fluid to act solely by its pressure and without any fluid flow onto the valve body of the restriction valve device.
According to the present invention, there is provided in a restriction valve device for hydraulic pres-sure fluid in a vehicle shock absorbing mechanism, said valve device being of the type comprising a valve seat member having at least one main opening for the passage of said pressure fluid, said main opening being closable by means of a movable valve body biased by a spring, and at least one auxiliary opening for the pressure fluid, said auxiliary opening being selectively closable by a closure element, an improvement wherein said valve device is configured to provide a closed var-iable space which is confined between the valve seat mem-ber and the valve body, the auxiliary opening being con-1263~
- 3a -nected with said space so that, when the closure element is open, the pressure fluid is admitted through said auxiliary opening to cause the pressure of said fluid so admitted to be exerted on said valve body and hence provide for an increased pressure force on said valve body against the force of the biasing spring so as to change functional characteristics of the restriction valve device without effecting any significant flow of the pres-sure fluid via said auxiliary opening.
According to the present invention, there is also provided a restriction valve device for hydraulic pressure fluid in a vehicle shock absorbing mechanism, comprising a valve seat member which defines at least one main opening for the passage of hydraulic pressure fluid therethrough, a movable valve body disposed adjacent said main opening, said valve body including a first por-tion for controlling the flow of pressure fluid through said main opening, spring means for urging said first portion of said valve body toward a closed position to said main opening, an auxiliary opening in said valve seat member for applying the pressure of said pressure fuid to a second portion of said valve body in a force direction opposite to the force exerted on said valve body by said spring means, and control means for selec-tively opening and closing said auxiliary opening to varythe total force which is exerted by said pressure fluid on said valve body in opposition to the force of said spring means thereby to vary functional characteristics of said restriction valve device, said auxiliary opening being so located relative to said valve body and valve seat member that there is no significant flow of pres-; sure fluid via said auxiliary opening past said valve seat member when said control means opens said auxiliary opening.

, ` ' :

~263;~1~

- 3b -According to the present invention, there is also provided a restriction valve device for hydraulic pressure fluid in a vehicle shock absorbing mechanism, comprising a valve seat having at least first and second passages extending therethrough in spaced relation to one another, a movable valve member disposed adjacent one end of each of said first and second passages, spring means for urging said valve member toward said one end of said first and second passages, the other ends of said first and second passages being exposed to the pressure of said hydraulic fluid whereby the pressure of said fluid is communicated via said first and second passages to spaced portions of said valve member to apply pressure forces to said valve member in opposition to the force of said spring means, said valve seat and valve member being so configured that when said valve member moves away from said one end of said first and sesond passages said hydraulic pressure fluid may flow through said first passage past said valve member but no significant flow of said hydraulic fluid can occur through said second passage past said valve member, whereby said first pas-sage act primarily as fluid flow passage while said second passage acts primarily as a pressure applying passage, and means for selectively closing the other end of said second passage to change the total fluid pressure force which is applied to said valve member in opposition to the force of said spring means thereby to control func-tional characteristics of said restriction valve device.
According to the present invention, there is also provided a restriction valve device for a hydraulic pressure fluid in a vehicle shock absorbing mechanism, comprising a valve seat member with at least one main passage for the flow of said pressure fluid, said main passage being closable by means of a movable valve body 12~;3 ~1~

- 3c -biased by spring means, and at least one auxiliary passage for pressure fluid for applying pressure from the pres-sure fluid onto the valve body, the flow of pressure fluid through said auxiliary passage being controlled by a clo-sure element, an improvement being distinguished by aclosed variable space confined between the valve seat member and the valve body, the auxiliary passage being connected to said space to provide under the control of the closure element for a variable pressure on said valve body against the force of the spring means so as to change functional characteristics of the restriction valve de-vice, said auxiliary passage extending through the valve seat member as well as through the valve body, the clo-sure element being adapted to variably decrease force from the pressure fluid onto the valve body against the force of the spring means.
A

1~63'~1~

Brief Description of the Drawings sy way of example the invention will be further described below with reference to the accompanying drawing in which Figure 1 is a diagrammatical longitu-dinal section through a shock absorber of a so-called twin-chamber type, Figure 2 illustrates in greater detail the portion of said longitudinal section indi-cated by broken lines in Figure 1, and Figure 3 is a longitudinal section similar to Figure 2 of another embodiment of the restriction valve device according to the invention.

Description of the Preferred Embodiments Although the restriction valve device according to the present invention can be applied in many diffe-rent connections, its advantages are most clearly evident as applied to vehicle shock absorbers. Such absorbers mainly are of two types, namely (a) so-called gas-dampers and (b) so-called twin-chamber dampers. The first-mentioned type of shock absorber comprises a cylinder, a piston with a piston rod, and a sealed volume filled with gas under a pressure of between 10 and 30 bar. Through a diaphragm the pressure acts on hydraulic liquid and prevents the liquid from starting to cavitate during the operation of the shock absorber.
The latter type of shock absorber consists of two cylinders, namely an outer and an inner cylinder, a piston with a piston rod, and a valve in the bottom of the shock absorber. The outer cylinder provides for expansion of the liquid during compression of the damper. This space has to be present due to the reduc-1~263~14 tion of volume which occurs in the inner cylinder whenthe piston rod moves downwardly (as seen in Figure 1 of the drawing). The present inventive restriction valve device can be applied to shock absorbers of both said kinds. When used in a gas damper a valve device is mounted at each side of the piston, and when used in a twin-chamber damper a restriction valve device according to the invention is disposed in the bottom of the inner cylinder and another is provided in the piston. In the following description the invention has been disclosed as applied to such a twin-chamber damper but of course this forms no limitation of the invention.
As known, a so-called twin-chamber damper of the type shown in Figure 1 operates in the following manner.
When piston 23 moves downwards (as illustrated in Figure 1) to compress the shock absorber, the damper is so designed that the liquid in the shock absorber will not be subjected to any sub-atmospheric pressure due to the liability of the liquid to cavitate. Should cavitation occur, the damping ability would be drastically impaired. Therefore, when compressing the damper no pressure differential exists on either side of the piston 23 since a check valve is mounted in the piston.
The damping force is created by restricting the liquid flow through the bottom valve (shown in greater detail in Figure 2) when the liquid passes from the inner to the outer cylinder. The over-atmospheric pressure acts on the area of the piston rod.
In expansion of such a twin-chamber absorber the damping force is formed due to the pressure differential across the piston. In the piston is mounted a restric-tion valve device like that shown in Figure 2, which gives the desired damping characteristics. The increase , .
.

1~3~4 in volume which occurs when the piston rod moves up-wardly (as seen in Figure 1) results in a suction of liquid from the outer to the inner cylinder through a check valve.
The present invention relates to an improved restriction valve device and the basic thought is that by said valve device for use in the afore-mentioned manner, two different kinds of restriction of the liquid flow are obtained. Said change of restriction charac-teristics furthermore occurs very fast (faster than 5 ms) and does not require too much power. In the pre-sent embodiment a valve device according to the inven-tion is illustrated as mounted in the bottom of a cylin-der of the shock absorber. In a complete shock absorber of this kind there is also a similar valve mounted in the piston.
As illustrated in Figure 2 of the drawing, a shock absorber of the twin-chamber type comprises an inner cylinder 21, concentrically arranged within an outer cylinder 22. Within the inner cylinder 21 is longitudinally movably mounted a piston 23 with an associated piston rod 24. In the bottom of the inner cylinder 21 is a double-acting valve mechanism which comprises a valve seat member 10 that is provided with at least one main passage 4 for the flow of the pressure fluid and at least one auxiliary passage 7 for the pressure fluid. The main passage 4 is closable at the outlet side by means of a movable valve body 5, biased against the valve seat member 10 by means of a biasing spring 6 as known per se. Furthermore, in the valve seat member 10 is arranged at least one return passage 25, which at the side of the valve seat member 10 opposite to the valve body 5 is closable by means of a spring ,, 1~t;3~1~

biased check valve 3 as also well known.
In a valve mechanism of this kind the damping action of the shock absorber when compressing the same, i e.when the piston 23 moves towards the valve mecha-nism, is determined by the pressure over the outlet area of the opening 4 against the force of the biasing spring 6. In order to provide for a change of this power inter-action there is arranged according to the present in-vention an auxiliary passage 7 through the valve seat means 10, said auxiliary passage 7 at its outlet side communicating with a space 11 that is confined between the valve body 5 and the valve seat member 10. In the embodiment illustrated in Figure 2 of the drawing said auxiliary passage 7 is located centrally of the valve seat means 10 and opens into the bottom of a cylindrical recess 10a, into which extends sealingly and slidable movable a corresponding cylindrical central projection 5a of the valve body 5. The end of auxiliary passage 7 remote from confined space 11 can be selectively opened or closed by a closure member 2. When closure member 2 is in the position illustrated in Figure 2, the over--atmospheric pressure occurring in the cylinder 21 upon compression of the shock absorber acts on the valve body 5 through the auxiliary passage 7 and the space 11 and thus creates an additional pressure force on the valve body 5 whichis counter-directed to the force of the biasing spring 6. As a result the valve body 5 will be urged further away from the opening 4 of the valve means 10. However no flow of pressure fluid occurs through the auxiliary passage 7 and the space 11 across the projec-tion 5a of the valve body 5.
Figure 3 shows another embodiment of the device according to the invention. In this Figure the same lZ63;~1~

reference characters as in Figure 2 have been used to denote similar elements.
In the embodiment of Figure 3 the auxiliary passage 7 is extended also through the valve body 5 and the closure member 2 is placed on the side of the valve body opposite the confined space 11. As in the embodi-ment of Figure 2 the over-atmospheric pressure occurring in the cylinder 21 upon compression of the shock absor-ber acts on the valve body 5 through the auxiliary passage 7 and the space 11, and the full pressure from the pressure fluid is applied to the valve body 5 and opposing the force of the biasing spring 6. By opening the closure member 2 some of the pressure of the pressure fluid can be relieved from the valve body in a controlled manner to change the restriction characte-ristics of the restriction valve device.
Although in the illustrated and above-described embodiments only one auxiliary passage 7 is used and said passage is located centrally, many modifications are of course possible in this connection in order to obtain the same action which will be obvious to those skilled in the art. Thus there might be a plurality of auxiliary passages 7, for instance circumferentially equally spaced around the longitudinal axis of the shock absorber in a manner similar to the main passages 4, and instead of a piston-like projection 5a on the valve body 5 the recess 1Oa in the valve seat means 10 might be covered by means of a diaphragm or the like (not illustrated) so as to form the confined space 11 for actuation of the valve body 5. Also the valve body 5 and the spring 6 can be replaced by a washer spring closing the main passage and defining a confined space in the valve seat member, the pressure in said space being controlled by means of an auxiliary passage and a coope-rating closure member.

1~63~1~

According to the invention the auxiliary passage 7 is closable by means of a movable closure member 2 which is movable from the exterior of the shock absorber in a suitable manner known per se, e g by means of a solenoid 1.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a restriction valve device for hydraulic pressure fluid in a vehicle shock absorbing mechanism, said valve device being of the type comprising a valve seat member having at least one main opening for the pas-sage of said pressure fluid, said main opening being clos-able by means of a movable valve body biased by a spring, and at least one auxiliary opening for the pressure fluid, said auxiliary opening being selectively closable by a closure element, an improvement wherein said valve de-vice is configured to provide a closed variable space which is confined between the valve seat member and the valve body, the auxiliary opening being connected with said space so that, when the closure element is open, the pressure fluid is admitted through said auxiliary opening to cause the pressure of said fluid so admitted to be exerted on said valve body and hence provide for an increased pressure force on said valve body against the force of the biasing spring so as to change functional characteristics of the restriction valve device without effecting any significant flow of the pressure fluid via said auxiliary opening.

2. A device according to claim 1, wherein a plurality of said main openings are spaced from one an-other around an axis of symmetry, said main o-penings having outlet sides closable by means of a disk-shaped portion of said valve body, said auxiliary opening being centrally located along said axis of symmetry, said closed space being provided between a central recess in said valve seat member and a protrusion of said valve body which is slidably movable in said recess and which sealingly engages the sides of said recess.

3. The restriction valve device of claim 1, wherein said valve seat member defines at least one return passage therein for the flow of pressure fluid therethrough in a direction opposite to the direction of pressure fluid flow through said main opening, and spring biased means for closing the end of said return passage which is remote from said valve body.

4. A restriction valve device for hydraulic pressure fluid in a vehicle shock absorbing mechanism, comprising a valve seat member which defines at least one main opening for the passage of hydraulic pressure fluid therethrough, a movable valve body disposed adjacent said main opening, said valve body including a first por-tion for controlling the flow of pressure fluid through said main opening, spring means for urging said first portion of said valve body toward a closed position to said main opening, an auxiliary opening in said valve seat member for applying the pressure of said pressure fluid to a second portion of said valve body in a force direction opposite to the force exerted on said valve body by said spring means, and control means for selec-tively opening and closing said auxiliary opening to vary the total force which is exerted by said pressure fluid on said valve body in opposition to the force of said spring means thereby to vary functional characteristics of said restriction valve device, said auxiliary opening being so located relative to said valve body and valve seat member that there is no significant flow of pressure fluid via said auxiliary opening past said valve seat member when said control means opens said auxil-iary opening.

5. The restriction valve device of claim 4, wherein said valve seat member and said second portion of said valve body cooperate with one another to define a confined space, the volume of which changes with movement of said valve body relative to said valve seat member, said auxiliary opening communicating with said confined space.

6. The restriction valve device of claim 5, wherein said valve seat member includes a recess, said valve body including a protrusion, the sides of which are in sliding sealing engagement with the sides of said recess, said confined space being defined between said protrusion and the portion of said recess which is not occupied by said protrusion.

7. The restriction device of claim 6, wherein said recess and said protrusion are each of cylindrical configuration.

8. The restriction device of claim 7, wherein said auxiliary opening is located at the central axis of said cylindrical recess, a plurality of said main o-penings being disposed in spaced relation to one another in a circular array surrounding said cylingrical recess.

9. The restriction device of claim 8, wherein said first portion of said valve body includes at least one disk-shaped member attached to and extending radially outward of said protrusion in overlying relation to one end of each of said main openings, said second portion of said valve body comprising the end of said protrusion interior of said recess which is disposed in facing re-lation to said auxiliary opening.

10. A restriction valve device for hydraulic pressure fluid in a vehicle shock absorbing mechanism, comprising a valve seat having at least first and second passages extending therethrough in spaced relation to one another, a movable valve member disposed adjacent one end of each of said first and second passages, spring means for urging said valve member toward said one end of said first and second passages, the other ends of said first and second passages being exposed to the pres-sure of said hydraulic fluid whereby the pressure of said fluid is communicated via said first and second passages to spaced portions of said valve member to apply pressure forces to said valve member in opposition to the force of said spring means, said valve seat and valve member being so configured that when said valve member moves away from said one end of said first and second passages said hydraulic pressure fluid may flow through said first passage past said valve member but no signif-icant flow of said hydraulic fluid can occur through said second passage past said valve member, whereby said first passage act primarily as fluid flow passage while said second passage acts primarily as a pressure applying passage, and means for selectively closing the other end of said second passage to change the total fluid pressure force which is applied to said valve member in opposition to the force of said spring means thereby to control functional characteristics of said restriction valve device.

11. A restriction valve device for a hydraulic pressure fluid in a vehicle shock absorbing mechanism, comprising a valve seat member with at least one main passage for the flow of said pressure fluid, said main passage being closable by means of a movable valve body biased by spring means, and at least one auxiliary pas-sage for pressure fluid for applying pressure from the pressure fluid onto the valve body, the flow of pressure fluid through said auxiliary passage being controlled by a closure element, an improvement being distinguished by a closed variable space confined between the valve seat member and the valve body, the auxiliary passage being connected to said space to provide under the con-trol of the closure element for a variable pressure on said valve body against the force of the spring means so as to change functional characteristics of the re-striction valve device, said auxiliary passage extending through the valve seat member as well as through the valve body, the closure element being adapted to var-iably decrease force from the pressure fluid onto the valve body against the force of the spring means.

12. A device according to claim 11, wherein the valve body and the spring means are constituted of a washer spring.

13. A device according to claim 11, comprising a plurality of said at least one main passage circum-ferentially spaced around an axis of symmetry, said pas-sages having outlet sides closable by means of the valve body having a disk - shaped portion, said auxiliary passage being centrally located, wherein for forming of the closed space the valve seat member is provided with a central recess and the valve body is provided with a protrusion sealingly and slidably movable in said recess.