WO2004022994A2

WO2004022994A2 - Damper for fluid vibrations comprising two diaphragms

Info

Publication number: WO2004022994A2
Application number: PCT/IB2003/003799
Authority: WO
Inventors: Filipe Franco; Patrick Desbois
Original assignee: Automotive Products France S.A.
Priority date: 2002-09-04
Filing date: 2003-08-29
Publication date: 2004-03-18
Also published as: AU2003253223A8; EP2140160A2; GB2408553A; GB0503913D0; WO2004022994A3; GB2408553B; AU2003253223A1; GB0220530D0; WO2004022994A8

Abstract

The invention is concerned with a damper having a housing (41) including a port (42) for connection with an associate fluid actuation system and a relatively flexible diaphragm (43) carried by said housing and defining therewith a chamber (50) with one face of the relatively flexible diaphragm in communication with the port so that the relatively flexible diaphragm may deflect in response to and hence damp low frequency vibrations transmitted through the hydraulic fluid in the associated actuation system to effect damping of such vibrations. A further diaphragm (46) is carried by the housing and positioned parallel to and proximate the other face of the relatively flexible diaphragm (43) so as to form a backup for the relatively flexible) diaphragm so that the relatively flexible diaphragm may deform against the further diaphragm in response to high frequency vibrations transmitted through the hydraulic fluid to cause deflection of the further diaphragm to effect damping of the high frequency vibrations. The relatively flexible diaphragm is sealed to the housing by a seal (44) having two lobes (44a) arranged concentrically one radially inside the other and which both project from the same side of the flexible diaphragm (43) and extend around a peripheral portion of the relatively flexible diaphragm.

Description

DAMPERS AND RESERVOIRS This invention relates to fluid dampers and fluid containing reservoirs.

In particular the invention is concerned with a damper, hereinafter referred to as a damper of the type specified, comprising a housing including port means for connection with an associate fluid actuation system, a relatively flexible diaphragm carried by said housing and defining therewith a chamber with one face of the relatively flexible diaphragm in communication with the port means so that the relatively flexible diaphragm may deflect in response to and hence damp low frequency vibrations transmitted through the hydraulic fluid in the associated actuation system to effect damping of such vibrations, and a further diaphragm carried by said housing and positioned parallel to and proximate the other face of the relatively flexible diaphragm so as to form a backup for the relatively flexible diaphragm so that the relatively flexible diaphragm may deform against the further diaphragm in response to high frequency vibrations transmitted through the hydraulic fluid to cause deflection of the further diaphragm to effect damping of the high frequency vibrations.

Such a damper is described and claimed in the Applicant's earlier European patent application no 01 117177.4.

Whilst dampers of the type described operate efficiently problems are experienced in sealing the relatively flexible diaphragm to the housing. Such relatively flexible diaphragms are also subjected to relatively high internal stress when they deflect which can also lead to premature failure.

It is an object of the present invention to provide a damper of the type specified which mitigates one or both of the above problems. Thus according to the present invention there is provided a damper of the type described in which the relatively flexible diaphragm is sealed to the housing by a seal having two lobes arranged concentrically one radially inside the other and which both project from the same side of the flexible diaphragm and extend around a peripheral portion of the relatively flexible diaphragm.

Preferably the relatively flexible diaphragm is formed from elastomeric material.

Preferably also the further diaphragm is a spring steel diaphragm.

Although the main application of the twin lobe seal arrangement of the present invention is seen as a fluid damper for use between a master cylinder and slave cylinder in a vehicle clutch actuating system other applications of this seal are envisaged. For example, this type of diaphragm seal is applicable to a fluid reservoir such as a fluid pressure accumulator in which pressurised fluid is stored in a chamber beneath a flexible diaphragm for supply to a fluid pressure actuating system. Another application of the twin lobe seal is, for example, as part of a fluid filled vehicle suspension damper.

The invention also provides a damper of the type described in which the relatively flexible diaphragm may have a dished configuration including a peripheral portion engaging with a peripheral portion of the further diaphragm and a central recessed portion positioned proximate to but spaced from the central portion of the further diaphragm.

In an alternative construction both diaphragms may be of a dished construction with the central recessed portions thereof projecting away from each other to maximise the volume therebetween or towards each other so that the diaphragms are in direct contact for greater support. The above dished diaphragm constructions allow the amount of deflection of the relatively flexible diaphragm before making contact with the further diaphragm to be tuned to provide the desired operating characteristics of the system in which the damper is to be fitted.

In accordance with a further inventive concept of the present invention there is provided a damper of the type described in which the flexible diaphragm has a central region bounded by an annular convoluted ridge which projects from the general plane of the diaphragm, this ridge being designed to straighten as the central region of the relatively flexible diaphragm is deflected due to changes in pressure within the damper chamber to allow deflection of the central region of the flexible diaphragm without any significant internal stressing of the diaphragm itself.

In a damper of the type described the relatively flexible diaphragm may have an axially extending lip which extends around the outer periphery of the further diaphragm between the further diaphragm and the walls of the housing to assist in sealing both diaphragms to the housing. This arrangement also assists in anchoring the flexible diaphragm to the housing.

Also in a damper of the type described the relatively flexible diaphragm may have a flexible central zone and a rigid annular outer zone bonded to the central zone, the rigid outer zone being clamped against the housing.

If desired, the rigid outer zone may include an integral sealing means. This sealing means could be provided on both sides of the rigid outer zone and could be an O- ring type seal or the twin lobe arrangement described above.

The invention also provides a hydraulic damper in which hydraulic fluid is confined in a chamber defined by a damper housing and a diaphragm, the diaphragm being held in sealed relation with the housing by an annular clamping ring which contacts the peripheral region of the diaphragm and is retained in position in the housing by a split-ring or similar fastening which engages a groove in the housing and is positioned beneath the claiming ring.

As will be appreciated, the various aspects of the present invention can be combined in a variety of combinations as will emerge from the following description.

Several embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which :-

Figure 1 shows a schematic diagram of a vehicle clutch operating system including a damper in accordance with the present invention;

Figure 2 shows details of the damper of figure 1 ;

Figure 3 shows a scrap view of part of the damper of figure 3;

Figure 4 shows a view on the line IV-IV of figure 2;

Figure 5 shows a modified form of the damper of figure 2;

Figure 6 shows a scrap view of part of the damper of figure 5;

Figure 7 shows a further modified form of the damper of Figure 2;

Figure 8 shows a further form of damper in accordance with the present invention;

Figure 9 shows a scrap view of part of the damper of figure 8;

Figure 9A shows how the diaphragm of the damper of Figures 8 and 9 deflects;

Figure 10 shows a yet further form of damper in accordance with the present invention; Figure 11 show a scrap view of part of the damper of figure 10;

Figure 12 shows yet a further form of damper in accordance with the present invention;

Figure 13 shows a scrap view of part of the damper of figure 12, and

Figures 14 and 15 show yet further forms of damper in accordance with the present invention.

Referring to Figure 1 this shows schematically a vehicle clutch operating system which includes a master cylinder 10, a slave cylinder 12, and a conduit 14 extending between the outlet of the master cylinder and the inlet of the slave cylinder.

Master cylinder 10 includes an input rod 16 connected in known manner to the clutch pedal 18 of an associated motor vehicle so that pivotal movement of the clutch pedal by the vehicle operator moves a piston of the master cylinder in known manner to discharge pressure fluid from the cylinder. Cylinder 10 further includes a flange 10a to facilitate attachment of the master cylinder to the firewall 20 of the vehicle.

Slave cylinder 12 is secured as by a bracket 22 to bell housing 23 enclosing the clutch 24 of the vehicle and includes an output rod 25 coacting in known manner with a clutch release lever 26 so that pivotal movement of clutch pedal 18 by the operator results in discharge of pressure fluid from master cylinder 10 for conveyance through conduit 14 to slave cylinder 12 to provide extension of output rod 25 and pivotal movement of release lever 26 to move clutch release bearing 27 in a direction to disengage the clutch 24. Clutch 24 is driven in known manner by a flywheel 30 which in turn is driven by an engine crank shaft 32.

Interposed in conduit 14 between master cylinder 10 and slave cylinder 12 is a damper 40. Damper 40 comprises a housing 41 having a port 42 for connection with conduit 14. A relatively flexible diaphragm 43 has, in accordance with the present invention, a twin lobe seal 44 which extends around a peripheral portion of the diaphragm 43 and which is clamped against an annular sealing surface 45 of housing 41. The lobes 44a of the seal are arranged concentrically one radially inside the other and both projecting from the same side of diaphragm 43.

On the side of the relatively flexible diaphragm 43 remote from port 42 a further diaphragm 46 is provided with diaphragms 43 and 46 being clamped against annular sealing surface 45 by an annular clamping ring or washer 47 held in position by a circlip 48 or similar split ring which engages an internal groove 49 in housing 41.

Relatively flexible diaphragm 43 includes an axially extending lip 43b which extends around the periphery of diaphragm 43 between the further diaphragm 46 and the housing 41 to assist in sealing the two diaphragms to the housing and anchoring the relatively flexible diaphragm 43 to the housing.

In the preferred construction the relatively flexible diaphragm 43 is formed from elastomeric material such as rubber and the further diaphragm 46 is formed from spring steel.

The relatively flexible diaphragm 43 is of a dished construction with a central recessed portion 43a positioned proximate to but spaced from the central portion 46a of the further diaphragm 46 to define an air-filled void 46b.

The damper is designed to operate so that as the pressure in the chamber 50 formed between the relatively flexible diaphragm 43 and housing 41 increases the relatively flexible diaphragm 43 is displaced towards the further diaphragm 46 thus damping the low frequency vibrations (e.g. 0-10 hertz) in the clutch operating system to which the damper is connected. Higher frequency vibrations (e.g. more than 20 hertz) are damped by contact of the relatively flexible diaphragm 43 with the further diaphragm 46 which forms a backup for the relatively flexible diaphragm 43 so that the two diaphragms together respond to high frequency vibrations in the actuating system thus damping these high frequency vibrations.

As will be appreciated the damping characteristics of the damper can be tuned by the amount of dishing of the relatively flexible diaphragm 43 in its central recessed portion 43a since this governs the volume of void 46b and the amount of movement of the relatively flexible diaphragm before the further diaphragm 46 comes into operation.

The housing 41 has a slotted cylindrical projection 51 surrounding the port 42 (see figure 4). This ensures that should the relatively flexible diaphragm 43 be drawn up towards the port 42 it will contact the axially outer end 52 of slotted projection 51 thus still allowing communication between the port and the chamber 50 via the slots 53 provided in the projection 51.

The housing 41 is formed from plastics material and has a central domed portion 41a and an outer peripheral portion 41b on which the sealing surface 45 is formed and against which the two diaphragms are clamped. In order to reinforce the domed portion 41a of the housing radially extending internal ribs 54 are provided which extend radially outwardly from the cylindrical projection 51.

As indicated above, the twin lobe diaphragm seal arrangement described above is suitable for a wide range of damper/fluid reservoir applications such as, for example, in a fluid pressure accumulator where the pressurised fluid is stored in the chamber between a flexible diaphragm or in, for example, fluid filled vehicle suspension dampers.

Figures 5 and 6 show an alternative form of the present invention in which both the relatively flexible diaphragm 143 and the further diaphragm 146 are both of a dished form with their central recessed portions 143a and 146a projecting away from each other in order to increase the clearance void 146b between the diaphragms in their unstressed condition. All the remaining details of figures 5 and 6 are as previously described in figures 1 to 4 and will therefore not be repeated but are simply marked with the same reference numerals as Figures 1 to 4 increased by 100. Figure 7 shows a further alternative form of the present invention in which both the relatively flexible diaphragm 543 and the further diaphragm 546 are both of dished form with their central recessed portions 543a and 546a projecting towards each other so that flexible diaphragm 543 is always supported by direct contact with the further diaphragm 546. The further diaphragm 546 is held in place by clamping ring 547 and circlip 548.

Figures 8, 9 and 9A show a further independent feature of the present invention which is a provision on the relatively flexible diaphragm 243 of an annular convoluted ridge 260 which surrounds a central region 243a of the diaphragm. The convoluted ridge 260 is arranged to be clear of the annular sealing surface 245 so that when, for example, the diaphragm 243 is displaced towards the diaphragm 246 this displacement results in the straightening of the convolution 260 as shown in the dotted detail of 243a' figure 8A. This straightening of the ridge 260 occurs without a significant internal stressing of the diaphragm thus significantly extending its operating life.

Figures 10 and 11 show a further independent feature of the present invention in which the relatively flexible diaphragm 343 has a flexible central portion 343a and an outer rigid portion 343b. The central portion 343a is formed from elastomate material such as rubber and is bonded to the rigid outer portion 343b which may be formed, for example, from metal or from rigid plastics material. The rigid outer portion 343b may be provided with integral seals 343c which, as shown in figure 11 , may be of the O ring type. Alternatively, these seals could be of the twin lobe type previously described with reference to figure 2 etc.

As shown in figures 10 and 11 the further diaphragm 346 is shown as being of a dished construction although it could be of a flat planer design if desired.

Figures 12 and 13 show yet a further combination of features of the present invention in which the relatively flexible diaphragm 443 has the flexible central portion 443a and rigid outer portion 443b shown in figures 10 and 11 and also includes the annular convoluted ridge 460 described above in relation to figures 8 and 9.

In the configuration shown in figures 12 and 13 the convoluted ridge 460 faces towards the further diaphragm 446 which is of a dished configuration.

As shown in Figure 14, the annular clamping ring or washer 47 held in place by the circlip 48 or other similar split ring which engages a groove 49 in housing 41 can be used to secure a relatively flexible diaphragm 43 and further diaphragm 46 in position whether or not diaphragm 43 has a peripheral twin lobe seal. For example, in Figure 14 the diaphragm 43 has a single peripheral sealing lobe 44b and an axially extending lip 43b.

Figure 15 shows the application of the clamping ring or washer 47 and circlip 48 to clamp a single metal diaphragm 46 to housing 41 with a separate seal 44c clamped therebetween.

Claims

1. A damper of the type described in which the relatively flexible diaphragm is sealed to the housing by a seal having two lobes arranged concentrically one radially inside the other and which both project from the same side of the flexible diaphragm and extend around a peripheral portion of the relatively flexible diaphragm.

2. A damper according to claim 1 in which the relatively flexible diaphragm has a dished configuration including a peripheral portion engaging with a peripheral portion of the further diaphragm and a central recessed portion positioned proximate to but spaced from the central portion of the further diaphragm.

3. A damper according to claim 1 in which the further diaphragm has a dished configuration including a peripheral portion engaging with a peripheral portion of the relatively flexible diaphragm and a central recessed portion positioned proximate to but spaced from the central portion of the relatively flexible diaphragm.

4. A damper according to claims 2 and 3 in which both diaphragms are of a dished construction with the central recessed portions thereof projecting away from each other

5. A damper according to claim 2 and 3 in which both diaphragms are of a dished construction with the central recessed portions projecting towards each other to be in direct contact.

6. A damper according to any one of claims 1 to 5 in which the flexible diaphragm has a central region bounded by an annular convoluted ridge which projects from the general plane of the diaphragm, this ridge being designed to straighten as the central region of the relatively flexible diaphragm is deflected due to changes in pressure within the damper chamber to allow deflection of the central region of the diaphragm without any significant internal stressing of the diaphragm itself.

7. A damper according to any one of claims 1 to 6 in which the relatively flexible diaphragm has a flexible central zone and a rigid annular outer zone bonded to the central zone, the rigid outer zone carrying the two seal lobes and being clamped against the housing.

8. A damper according to any one of claims 1 to 7 in which the diaphragms are held against the housing by an annular clamping ring which contacts the peripheral region of the further diaphragm and is retained in position in the housing by a split ring or similar fastening which engages a groove in the housing and is positioned beneath the clamping ring.

9. A damper according to any one of claims 1 to 8 in which the relatively flexible diaphragm is formed from elastomeric material.

10. A damper according to any one of claims 1 to 8 in which the further diaphragm is formed from spring steel.

11. A damper according to any one of claims 1 to 10 in which the relatively flexible diaphragm may have an axially extending lip which extends around the outer periphery of the further diaphragm between the further diaphragm and the walls of the housing to assist in sealing both diaphragms to the housing and anchoring the flexible diaphragm to the housing.

12. A damper of the type described in which the relatively flexible diaphragm has a dished configuration including a peripheral portion engaging with a peripheral portion of the further diaphragm and a central recessed portion positioned proximate to but spaced from the central portion of the further diaphragm.

13. A damper of the type described in which the flexible diaphragm has a central region bounded by an annular convoluted ridge which projects from the general plane of the diaphragm, this ridge being designed to straighten as the central region of the relatively flexible diaphragm is deflected due to changes in pressure within the damper chamber to allow deflection of the central region of the flexible diaphragm without any significant internal stressing of the diaphragm itself.

14. A damper of the type described in which the relatively flexible diaphragm has a flexible central zone and a rigid annular outer zone bonded to the central zone, the rigid outer zone being clamped against the housing.

15. A damper according to claim 14 in which the rigid outer zone includes an integral sealing means for contact with the housing and/or the further diaphragm.

16. A damper according to claim 15 in which the sealing means is of the O-ring type.

17. A damper of the type described in which the diaphragms are held against the housing by an annular clamping ring which contacts the peripheral region of the further diaphragm and is retained in position in the housing by a split-ring or similar fastening beneath the clamping ring which engages a groove in the housing.

18. A hydraulic damper in which hydraulic fluid is confined in a chamber defined by a damper housing and a diaphragm, the diaphragm being held in sealed relation with the housing by an annular clamping ring which contacts the peripheral region of the diaphragm and is retained in position in the housing by a split-ring or similar fastening which engages a groove in the housing and is positioned beneath the clamping ring.

19. A fluid reservoir/accumulator in which pressurised fluid is stored in a chamber bounded in part by a flexible diaphragm which is sealed to a housing by a seal having two lobes arranged concentrically one radially inside the other and which both project from the same side of the flexible diaphragm and extend around a peripheral portion of the flexible diaphragm.

20. A damper of the type described constructed and arranged substantially as hereinbefore described with reference to and as shown in Figures 1 to 4 or 5 and 6 or 7 or 8, 9 and 9A or 10 and 11 or 12 and 13 or 14 or 15 of the accompanying drawings.