GB2369415A

GB2369415A - Improved variable operation shack-absorber

Info

Publication number: GB2369415A
Application number: GB0205015A
Authority: GB
Inventors: Zarazaga Manuel Gaston
Original assignee: Quinton Hazell Espana SA
Current assignee: Quinton Hazell Espana SA
Priority date: 1999-08-04
Filing date: 1999-08-04
Publication date: 2002-05-29
Anticipated expiration: 2019-08-04
Also published as: WO2001011255A1; GB0205015D0; AU5291399A; DE19983973T1; GB2369415B

Abstract

The shock-absorber comprises a cylindrical casing (1) wherein is concentrically mounted a cylindrical body (4) wherein a displaceable hollow rod (7) is associated to a piston (8) with valve means to communicate a compression chamber (9) set between a pressure relief valve (5) closing the lower extremity of the cylindrical body (4) with an extension chamber (10). Thereby, there is provided a fluid compensation in the displacements of the rod (7) with the piston (8) of the shock-absorber when the vehicle runs in holes or over bumps on the road. The shock-absorber includes a solenoid valve to regulate the rigidity of the shock-absorber, the valve body (24) being comprised of a unique part which is obtained from a bush to which is made a wedge-type annular cut with trapezoidal cross-section; the cut is filled with solder of amagnetic material (27); the external and internal surfaces of said body (24) are then machined; the amagnetic material acts as a gap impeding the circulation of magnetic current through the valve body (24).

Description

t\:t.- 5: -._ \ - 1 t., 4, - < PERFECTED VARIABLE ACTION SHOCK ABSORBER

DESCRIPTION

5 OBJECT OF THE INVENTION

The present invention relates to a variable action shock absorber, which has been perfected in determined structural components thereof, specifically in a valve element by means of which the stiffness of the shock absorber itself can be varied.

It is an object of the invention to facilitate a shock absorber applicable in the field of wheeled transport, specifically in motor- driven vehicles, which is based

on a specific type of hydraulic shock absorber, but which incorporates some innovations in the configuration and fabrication of the valve element which permits a 15 good dimensional control to be ensured of the valve assembly at a reduced cost.

BACKGROUND OF THE INVENTION

The hydraulic shock absorbers of variable action or characteristic that 20 are mounted in motor vehicles and similar, are prepared to counteract in part the "bumps" that occur in the event of prominences and/or potholes found in the surface over which a vehicle is running. That is, the irregularities which through deficient wxwcution or through deterioration of the surface (pavement, road, tracks, etc.), are counteracted by the shock absorbers which are fitted on vehicles in order to achieve 25 a comfortable and agreeable ride for the passengers.

Clearly numerous types of shock absorber are known which are applicable to vehicles depending on the use or traffic characteristics for which the shock absorber in question has been designed.

?, ,.:; =j it,,{:,;.!' 'in.

<r:: - 2 In any case, in the European patent of the same author with publication number 0297194, a shock absorber is described of variable action, controlled electrically and foreseen for its application in motor vehicles.

5 Said shock absorber is formed from a casing with one of its ends prepared for being fastened, by means of the pertinent support or suitable means, to the wheel of the vehicle, whilst the other end is prepared for fixing to the bodywork.

On the inside of this casing of the shock absorber is mounted an axial and concentric cylinder, which at one end is closed by means of a relief valve element capable of 10 communicating the peripheral chamber determined between said cylinder and the casing, with the chamber determined between said valve body and a piston sliding on the inside of the cylinder, the opposite end of the latter being provided with a capping element. 15 The piston sliding on the inside of the cylinder is attached, by its end opposite to that of the aforementioned pressure relief valve, to a hollow rod which by its opposite end is attached to the pertinent means of fastening the shock absorber assembly to the casing or bodywork of the vehicle, with the particularity that the chamber 20 determined between the sliding piston and the relief valve is termed compression chamber, whilst the chamber determined between said sliding piston and the closed end of the cylinder is termed extension chamber, both chambers being occupied by the hydraulic fluid (normally oil). The piston is provided with a series of ducts which communicate the two chambers referred to, and to which ducts are attached valves which permit oil to pass in a single direction for each group of ducts; that is, some permit oil to pass from the compression chamber to the extension chamber, and the others permit the oil to pass 30 in the opposite direction, that is from the extension chamber to the compression :, \

4 1- 3

t- chamber, in such a manner that in each case the closure of one of the extremities of these ducts is determined by a spring-loaded valve.

With respect to the pressure relief valve fitted at the lower end of the 5 cylinder mounted axially and concentrically in the casing of the shock absorber, it is bi-directional, that is, it permits the oil to pass from the so-called compression chamber to the annular and external chamber determined between the cylinder and the casing, chamber which is hereinafter termed "compensating chamber", in such a manner that depending on the position of the sliding piston the oil shall pass from the 10 compression chamber to the compensating chamber or vice versa.

With these characteristics the shock absorber works in a manner such that when the vehicle encounters a protuberance or a pothole on the roadway, the displacement shall occur in one direction or the other of the piston and therefore the 15 reduction in volume of the compression chamber and thereby the increase in that of the extension chamber and vice versa, giving rise thereby to the adequate transfer from one to the other through the openings in the piston, as well as the transfer of oil from the compression chamber to the compensating chamber or vice versa.

20 However, the shock absorber referred to includes also a valve which enables the stiffness to be changed of the shock absorber itself, adapting thus to the variable conditions of the roadway and to the different styles of driving, said valve being operated electrically through a solenoid which permits discharging of the extension chamber and thus make possible the variation in proportional form of the 25 suspension characteristics, foreseeing for this purpose that the axial cylinder with which the sliding piston is associated is hollow in order to incorporate on its inside a double body formed by two hollow and mutually concentric cylinders, the interior of which is fixed at one of their ends to the pressure relief valve itself, whilst the other end remains in the interior of the cylinder which is outermost and associated with the 30 solenoid valve itself, the actuation of which permits the communication to be formed

-4 I from the chamber established between the external cylindrical body of the two last mentioned and the hollow stem in which is axially and concentrically housed the former, with the outlet chamber established precisely in the two cylindrical concentric bodies, permitting the passage of the fluid from the extension chamber to the 5 compensating chamber, it being possible in this manner to vary the stiffness of the shock absorber, since the operation of the aforementioned solenoid valve permits discharging part of the volume in the extension chamber to the compensating chamber via the two concentric cylinders formed inside the hollow stem. That is, part of the volume in the chamber determined between the hollow stem and the outermost of the 10 two concentric cylinders is emptied into the compensating chamber, thus reducing the difference in pressure on the sliding piston and as a consequence the flow of fluid through this shall be less, being less the dissipation of energy by viscous friction through the piston itself and therefore reducing the stiffness of the shock absorber both in compression and in extension.

The valve assembly is constituted from a cylindrical body, around which is arranged a solenoid coil, whilst internally it incorporates a sliding piston which, depending on the position it occupies, disables or enables communication between the extension chamber and the compensating chamber. To this end the valve body is made 20 up of two parts or pieces separated by an air gap such that the lines of the magnetic field have their path blocked through the valve body, being closed through the sliding

piston and provoking, due to the force of magnetic induction, the displacement thereof and the enabling of said communication between the chambers mentioned.

25 However, the aforementioned solenoid valve mounted on the shock absorber corresponding to said European patent, has been improved in determined structural aspects thereof in order to achieve new facilities and better dimensional control of the valve body itself and particularly insofar as the constitution of the valve body is concerned

-2A - 5 -

^\G __.

DESCRIPTION OF THE INVENTION

The variable action shock absorber which is proposed is based precisely on that described in European patent 0297194 referred to in the previous section, and 5 presents as fundamental innovation the incorporation of a new type of solenoid valve and elements associated therewith, in order not only to achieve optimal performance in its operation, but also to achieve a more straightforward fabrication of the valve assembly, resulting in a reduction in its price.

10 One of the improvements object of the invention relates to the configuration of the valve body and, specifically, to that said valve body is made up of a single piece obtained from a cylindrical shell on which is practiced a wedge shaped notch which determines a radial channel, having cross section in the form of a truncated cone, the inside of which is filled, by means of welding metal, with an 15 amagnetic material, proceeding thereafter to the machining of the inside and outside face of the aforementioned valve body.

This manner of implementing the valve body permits good dimensional control thereof to be assured and its manufacture in a straightforward and economical 20 way.

A further novel characteristic is the fact that the spring that presses against the sliding piston produces always an axial thrust on the aforementioned piston, for which said spring rests at one of its extremities on a ledge prepared for this 25 purpose in a kind of thick washer which rests precisely on the end of the sliding piston, whilst at the other end the spring referred to rests on a self-centring ring or disc, with a circular and concentric projection, such that its outside diameter shall be in correspondence with the inside diameter of the spring itself, whilst the upper or external base superior of said disc has a boss that is positioned in a depression made 30 for this purpose in the bottom of the valve body, thereby achieving a self-centring of

V''\;\. -6

^ C- -. 21 - 4,. - r the spring itself, which ensures an axial thrust at all times on the sliding piston, termed also valve core.

Finally, and as another novel characteristic, provision is made that 5 between the sliding piston or valve core mentioned and the valve body itself, there be a hermetically sealing joint which prevents any type of leakage that might arise from the opening provided for this purpose in said valve body and which is opened and closed by the piston when it slides.

10 DESCRIPTION OF THE DRAWINGS

To complete the description being made and for the purpose of assisting

in a better understanding of the characteristics of the invention, in accordance with a preferred example of practical embodiment thereof, as an integral part of said 15 description, a collection of drawings is attached in which, by way of illustration and

not restrictively, the following is shown: Figure 1.- A longitudinal illustration is shown in cross section of the shock absorber implemented in accordance with the object of the invention.

Figure 2.- An enlarged view is shown of the assembly which constitutes the solenoid valve as novel element of the invention.

Figure 3.- A schematic illustration is shown of how the valve body is 25 obtained, according to the object of the present invention.

PREFERRED EMBODIMENT OF THE INVENTION

As can be seen from the figures mentioned, the variable action shock 30 absorber in which are applied the improvements object of the invention, is constituted

| tI\\ , urad ,. Ha To I p lca. 6 1,;-z? 7 Or from a cylindrical casing (1), which on one of its ends has the means (2) appropriate for its fastening, via a support or whatever other conventional system, to the wheel of a vehicle, whilst at the opposite end it has means (3) for fastening to the bodywork of the same vehicle.

On the inside of the casing (1) is mounted axially and concentrically a cylinder (4) on one of the ends of which is fitted a pressure relief valve (5), whilst the opposite end is closed by means of a body (6) included on said opposite and end zone proper of the casing (1).

On the inside of the cylinder (4) is mounted, with capacity for axial displacement, a hollow rod (7), with one of its ends in association with a sliding piston (8) on the inside of the cylindrical body (4), piston (8) which establishes in said body (4) two chambers (9) and (10), the first of these being termed compression and the 15 second extension.

The sliding piston (8) is held to the hollow rod (7) by means of an intermediate body (11).

20 The compression chambers (9) and extension chambers (10) are filled with oil and are capable of communicating through the groups of openings (12) and (12'), in such a manner that the first group of openings (12) permits the passage in a single direction of the fluid or oil, specifically from the extension chamber to the compression chamber (9), whilst through the openings (12') both chambers can be in 25 communication, but only in the direction running from the compression chamber (9) to the extension chamber (10), those groups of openings (12) and (12') being closed at one end and open at the opposite one, by means of respective valves, constituted in each case by a small plate (13) or (13') and a spring (14) or (14').

30 With respect to the pressure relief valve (5), this is provided in order

11 rmc 6 < n,= 2z 420 \. - 8 AlC 014, ORi,.

out -'I that the compression chamber (9) and the chamber (15) termed compensating can communicate, and is established between the cylinder (4) and the casing (1) of the shock absorber, in such a manner that said chamber (15) contains one part of hydraulic fluid or oil, whilst the remainder is occupied by air or gas at a pressure equal to or 5 greater than atmospheric for the purpose of permitting offsetting of the variations produced in the volume of the compression chamber (9) during shock absorber operation. In the body constituting said valve (5), some openings (16) have been 10 provided which are closed by means of a small plate (17) against which pushes a spring (18), permitting communication in both directions between the aforementioned compression chamber (9) and the compensating chamber (15).

In accordance with these characteristics, the operation of the shock 15 absorber is as follows: When the vehicle wheel which is associated with said shock absorber encounters a protuberance in the hardtop or road surface, a force is exercised which tends to displace upwards the casing (1) and at the same time the cylindrical body (4), 20 producing a reduction in the volume of the compression chamber (9) and an increase in the volume of the extension chamber (10), which results in a pressure difference between the two chambers which shall cause oil to flow from the compression chamber (9) to the extension chamber (10), through the transfer openings (12').

25Meanwhile, this difference in pressure causes the oil to flow between the compression chamber (9) and the compensating chamber (15) itself, through the openings (16) established for this purpose in the pressure relief valve (5).

However, when the wheel of the vehicle encounters a pothole, the 30opposite effect takes place, that is extension of the shock absorber is produced, the

- I; i;; l l i i.

r,,, , o',, 4, i locale. 'at;: 1 _ 9 _ _. casing (1) and therefore the cylindrical body (4) being displaced downwards, producing an increase in volume of the compression chamber (9) and a diminution in the extension chamber (10), causing the oil to flow from the latter towards the aforementioned compression chamber (9). Simultaneously, the transfer is produced of 5 oil from the compensating chamber (15) to the compression chamber (9), in order to offset the increase in volume undergone in the latter.

The shock absorber described, and which corresponds to the characteristics of that referred to in European patent 0297194, includes, moreover, 10 axially and concentrically a pair of cylinders (19) and (20), this last one joined, through a socket (21), to the body proper of the pressure relief valve (5), whilst the external cylinder (19) is joined at the opposite end to the solenoid valve assembly which said shock absorber incorporates, provision having been made that those cylinders (19) and (20) establish an outlet chamber (22) whilst between the hollow rod 15 (7) and the outermost cylinder (19) of the two referred to, an annular compensating chamber (23) is formed, both chambers (22) and (23) being connected through a radial opening (34) provided in the valve body (24).

The solenoid valve, provided in order to be able to change the stiffness 20 of the shock absorber, is constituted habitually of a valve body (24) formed by two pieces separated by an air gap over which is wound the coil (25), there being arranged on the inside of the valve body (24) a piston (26) which can be displaced inside the valve body (24) in response to the operation of the solenoid coil (25) since the air gap prevents the flow of the magnetic flux through the valve body. The displacement of 25 the piston (26) results in the opening or closing of the communication channel (34), piston which is forced towards the closed position of the opening (34) by means of a spring (28).

In this manner it is possible to vary the stiffness of the shock absorber, 30 the solenoid valve described being foreseen for discharging part of the volume of the

-.2---;, - ail,'. i',,-,,...t'RiN0 ' r ret '- - 10 la. o14 A. extension chamber (10) into the compensating chamber (IS), via the cylindrical bodies (19) and (20), in such a manner that the operation of said solenoid valve empties part of the volume of the chamber (23) into the compensating chamber (15), reducing the difference in pressure in the hollow rod (7) and as a consequence, the flow of fluid 5 through said piston shall be less, likewise being less the dissipation of energy through viscous friction through said hollow rod (7), whereby the stiffness of the shock absorber is reduced, both in compression and in extension.

Thus, one of the improvements object of the invention relates to the fact 10 that the valve body is constituted by a single piece obtained from a shell (24) in which is practiced a wedge-shaped annular notch, defining a channel of trapezoidal section, which is filled, by means of welding metal, with an amagnetic material (27), the inside and outside faces of the valve body (24) being machined thereafter, in such a manner that this amagnetic material (27) acts as an air gap preventing the circulation of 15 magnetic flux through the valve body (24).

Another innovation of the invention, relates to the fact that the spring (28) which pushes the sliding piston (26) rests at one end on a ledge of a kind of thick washer (29) conveniently located on a chamfer or flaring from the end of the sliding 20 piston (26), as can be clearly appreciated in figure 2, whilst the other end of said spring (28) rests in a guided manner on a disc (30) with a circular protuberance (31) the outside diameter of which corresponds precisely with the inside diameter of the spring (28), the object being that the latter be perfectly centred between the kind of thick washer (29) and the disc (30), the latter being self-centred by means of a 25 protuberance or projection (32) of convex surface which is located in a complementary depression provided in the bottom of the valve body (24) itself, as may also be clearly seen in figure 2, so achieving perfect self-centring of the spring (28), thereby guaranteeing an axial thrust at all times on the sliding piston (26), at the same time as the convex-surfaced projection (32) permits swivelling of the disc (30) in all directions 30 and as a consequence of the spring (28), the self-centring effect to which allusion is

-;--':i' - -:''i r 1, ' I aC3 2 1 to - 11 Wo \)D made above is achieved.

The fact must likewise be noted that on the sliding piston (26) has been incorporated a hermetically sealing O-ring (33), which rests against the inside surface 5 of the valve body (24), establishing a hermetic seal between the two bodies, and preventing possible leakage that could arise through the radial opening (34) that establishes communication, depending on the position of the piston (26), between the outlet chamber (22) of the cylindrical bodies (19) and (20) and the annular compensating chamber (23), established between the cylinder (19) and the hollow rod 10 (7).

Claims

\ - CLAIMS

1.- Perfected variable action shock absorber, which being constituted from a cylindrical casing (1) with means (2) and (3) for fastening to the wheel and 5 bodywork of a vehicle, being equipped on the inside with a cylinder (4) with one of its ends fitted with a pressure relief valve (5), through which a chamber (9) can communicate with an extension chamber (10), the first of these established between the valve (5) and a sliding piston (8) on the inside of the cylindrical body (4), and the second established between the latter and the external casing (1), said sliding piston (8) 10 having valve means which permit unidirectional communication between the chambers (9) and (10), and that sliding piston (8) also being in association with a hollow rod (7) which by its opposite end is fixed to the means of fastening (3) to the vehicle bodywork, having also some internal and concentric cylindrical bodies (19) and (20), between which is established an outlet chamber (22) connected, by means of a radial 15 opening (34), with a compensating annular chamber (23) defined between the cylinder (19) and the inside wall of the hollow rod (7), establishing communication or closure between the two chambers (22) (23) by means of a solenoid valve constituted from a valve body (24) which has two parts or pieces of magnetic material separated by an air gap, and upon which is wound a coil (25), being mounted inside the valve body a 20 sliding piston (26) which can be displaced on the inside of the valve body (24) in response to the operation of the solenoid coil (25) in order to open or close the communication channel (34), the sliding piston (26) being compelled towards the closed position of the opening (34) by means of a spring (28), is characterized in that the valve body (24) is constituted in a single piece, obtained from a shell in which a 25 wedge- shaped annular notch has been practiced, of trapezoidal section, the inside of which is filled, by means of welding metal, with an amagnetic material (27), the outside and inside faces of the valve body being machined thereafter, in such a manner that the amagnetic material (27) acts as an air gap to prevent the circulation of the magnetic flux through the valve body (24).

-; i,, i..-.,,l 1; it I juerzCo d.- It a =74 o i - 13 t6,c, Ga 5 it, - ?. \1) _

2.- Perfected variable action shock absorber, in accordance with claim 1, characterised in that the spring (28) rests on one side against a thick washer (29) which pushes the piston (26) and at the other end on a disc (30) which permits the self-

centring of the spring, for which purpose the supporting disc (30) has on its outside 5 surface a projection of convex surface (32) which rests in a complementary depression established for this purpose in the bottom of the valve body (24), permitting the swivelling of said disc (30) in all directions and therefore of the spring (28) in order to achieve thereby an axial thrust of the spring on the piston or valve core.

10

3.- Perfected variable action shock absorber, in accordance with claim 1, characterised in that the sliding piston (26) comes with a hermetically sealing O-ring (33), which rests against the inside surface of the valve body (24), establishing a hermetic seal preventing possible leakage that could arise through the side opening (34).