GB2244784A

GB2244784A - Elastomeric mounting

Info

Publication number: GB2244784A
Application number: GB9012702A
Authority: GB
Inventors: William John Mortel
Original assignee: Dunlop Ltd
Current assignee: Dunlop Ltd
Priority date: 1990-06-07
Filing date: 1990-06-07
Publication date: 1991-12-11
Anticipated expiration: 2010-06-07
Also published as: FR2663099A1; JPH04231742A; GB2244784B; NL9100964A; GB9012702D0; DE4118818A1

Abstract

A heavy duty elastomeric mounting (10) comprising a pair of rigid end members (11, 12) which define a pair of confronting surfaces (13, 14) each of substantially planar form and between those surfaces at least two discrete elastomeric bearing elements (15) arranged with the elastic centre to lie at infinity. Preferably each elastomeric bearing element is of an asymmetric construction about a median plane lying between the rigid end members to assist in reducing resonance and vibration transmission. <IMAGE>

Description

d 1.

ELASTOMERIC MOUNTING This invention relates to an elastomeric mounting and in particular, although not exclusively, to an elastomeric mounting such as is used in a marine engine installation and which typically comprises a thick layer of elastomeric material bonded ibetween flat confronting surfaces of a pair of rigid end members, those surfaces generally being arranged to lie in horizontal or inclined planes when in situ to support a marine engine.

The standard elastomeric mountings manufactured for land based use generally are intended to support machinery of lighter weight than that of marine engines. For marine installations typically it is necessary to provide a large number of the standard elastomeric mountings in order that the elastomeric material of each mounting is not over-stressed and unable effectively to absorb vibration. For a large marine engine inst;-;!'L;-:i--ion it can be necessary to provide up to 100 conventional mountings though this may be reduced to, say, 24 by providing specially manufactured larger size mountings. However, the decrease in number of individual mountings arising from use of larger mountings is not wholly advantageous. Whilst there is the advantage of a reduction in installation time and expense, difficulties can arise in moulding the larger size mountings and furthermore it is found that the larger size mountings generally are not so effective to adequately absorb high frequency vibrations which lie within the audible range.

The present invention seeks to provide an improved elastomeric mounting of a kind suitable for heavy duty use and which facilitates ease of manufacture and installation whilst also being effective to reduce transmission of high frequency vibrations which lie in the audible range.

In accordance with one aspect of the present invention there is provided an elastomeric mo unting 2. comprising a pair of rigid end members which def ine a pair of confronting surfaces, said surfaces being maintained spaced apart by interposed resilient elastomeric material, the elastomeric material being provided by at least two discrete elastomeric bearing elements each arranged to extend between said end members and to act in parallel with one another resiliently to resist relative movement of the end members in a normal direction generally perpendicular relative to said confronting surfaces and which tends to move the members towards and away from one another, and each said elastomeric bearing element having a thickness of at least 50 mm as considered in said normal direction.

Preferably each said confronting surface is "effectively planar" by which is meant that the confronting surfaces do not impose any significant sideways load on the elastomeric bearing elements in a direction perpendicular to said normal The confronting surfaces may be truly flat or at least one of them may be profiled in a balanced manner whereby locally induced sideways components of force on an individual elastomeric bearing element are balanced for that element as a whole.

Elastomeric material of at least one elastomeric bearing element may be bonded or otherwise secured directly to one or each of the rigid end members. Alternatively at least one of the elastomeric bearing elements may have one or a pair of end f ace members of metal or other substantially rigid material to which elastomeric material of the bearing element is secured, e g by bonding, and which end f ace member in turn is securable, e g by spot welding, to one of said rigid end members. An end face member may be of a truly planar f orm, i e f lat, or may be prof iled so as to depart from a truly planar form but be "effectively planar" in the manner described above in respect of profiling of confronting surfaces of the rigid end 3. members.

Preferably each elastomeric bearing element is asymmetric about a median plane which lies mid-way between said confronting surfaces of the rigid end members and is perpendicular to said normal direction. The asymmetry ritay result from provision of a profiled confronting surface or end face member at one end of the elastomeric bearing element and a truly planar surface at the other end, or each end of an elastomeric bearing element may be secured to a confronting surface or be provided with an end face member the profile of which is different at one end of the bearing element from that at the other end.

Alternatively asymmetry may be provided by arranging that the elastomeric material of each bearing element is non-uniform cross-section, to vary differently at respective sides of a median plane. In a further alternative asymmetry may be achieved for example by provision of an intczledf of reinforcing material which lies asymmetrically relative to the median plane.

It is to be appreciated that the aforementioned means for achieving asymmetry are not mutually exclusive and that two or more may be provided in combination.

Although the invention provides an elastomeric mounting in which the thickness of each elastomeric bearing element as considered in said normal direction is at least 50 mm, it is particularly envisaged that the thickness shall be greater than 75 mm. It is however further envisaged that the thickness shall be less than 200 mm.

The invention further teaches that the volume of elastomeric material in each bearing element shall be less than 7.5 litres and more preferably less than 5 litres.

The cross-sectional area of each elastomeric bearing element at the median plane preferably does not exceed 0.10 square metres and more preferaSly is 4. less than 0.05 square metres.

Preferably the cross-sectional area at the median plane lies in the range 2 to 0. 2 and more preferably 1.0 to 0.3 times the thickness of the element (i e distance between the rigid end members in said normal direction), the area and length being measured in like units.

Preferably the elastomeric material of each bearing element has a hardness in the range 35 to 70 Shore A. Suitable materials include natural rubber, nitrile rubber, chloroprene and natural/synthetic rubber blends.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings in which:Figure 1 is a side view of an elastomeric mounting in accordance with the present invention; Figure 2 is a plan view of the mounting of Figure 1; Figure 3 is a section on the line X-X of Figure 2; Figure 4 is a side view of a mounting in accordance with another embodiment of the invention; Figure 5 is a sectional view, corresponding to that of Figure 3, of the mounting of Figure 4; Figure 6 is a side view of a mounting in accordance with a further embodiment of the invention; Figure 7 is an end view of the mounting of Figure 6, and Figures 8, 9 and 10 are side views of mountings in accordance with yet further embodiments of the invention.

An elastomeric mounting 10 comprises a pair of rigid metal end members 11, 12 which define a pair of planar confronting surfaces 13,14.

0 5.

Each end member. is of a rectangular shape in plan and (when the mounting is in an unloaded condition) the two end members are maintained spaced apart at a spacing of 100 mm (in a normal direction perpendicular to the planar surfaces 13,14) by an interposed pair of elastomeric bearing elements 15. In this embodiment each element is of square shape in plan, but for example a rectangular cross-sectional shape may be used.

Each elastomeric bearing element 15 is formed from natural rubber and end faces of each element are bonded to respective confronting surfaces 13,14 of the rigid end members. The bearing element material has a hardness of 55 Shore A and each element has a volume of 3 litres. For each element the cross-sectional area at the median plane is 0.034 square metres.

Each elastomeric bearing element 15 is of an asymmetric construction comprising an outwardly extendling rib formation 16 which extends continueusly 1 2 around the periphery of the element as considered in plan and lies adjacent one side of a median plane 17 mid-way between the ends of the element.

The rib portion of one element lies above the median plane and the other below that plane as illustrated by Figures 1 and 3, Figure 3 showing in its left and right-hand portions sections through respectively parts of the left and right-hand elements of Figure 1. Thus the elements 15 are each of the same overall shape but are of reverse orientation in situ between the end members 11,12.

The end plates 11,12 are provided with apertures 18 to facilitate attachment to supported and supporting structure.

In a modification of the first embodiment the two bearing elements 15 are arranged in corresponding orientations such that their rib formations 16 each lie offset to the same side of the median plane.

In a second embodiment of the invention, 6. illustrated with reference to Figures 4 and 5, an elastomeric mounting is constructed substantially as described in respect of the preceding embodiment except that each elastomeric bearing element 151 has a metal reinforcing interleaf 20 embedded therein. The interleaf 20 is airanged to lie in a plane parallel with the confronting surfaces 131,141 of the end members 111,12' and to be spaced a small distance from the median plane 171. The elastomeric material of each bearing element is bonded to the confronting surfaces 131,141, as in respect of the first embodiment, and also to the surfaces of the reinforcing interleaf.

In a third embodiment illustrated in Figures 6 and 7, a pair of rigid end members 61,62 of a mounting 60 have bonded therebetween two bearing elements 63 each of a trapezoidal shape in cross-section as viewed in Figure 6. The elements 63 are each of a uniform depth as apparent f rom the end view of Figure 7. In the illustrated arrangement each elemei--,.,03 is arranged with its end of smaller area bonded to the upper end member 61 but in a modified construction one of the elements may be of reversed orientation whereby each of the end members 61,62 has bonded thereto the larger end of one element and the smaller end of the other element.

In the embodiment illustrated in Figure 8 a pair of end members 81,82 of a mounting 80 are maintained spaced apart by a pair of elastomeric bearing elements 83 each having identical external profiles. The bearing elements are, however, each of an asymmetric form insofar as they each have embedded therein a metal reinforcing -interleaf 84 which is inclined (in the direction as viewed in Figure 8) relative to the planes of the confronting surfaces of the end members 81,82. Thus for each bearing element the reinforcing interleaf in its inclined orientation results in asymmetry about the median plane lying between ends of the element.

Figure 9 shows an elastomeric mounting 90 1 7. constructed substantially similar to that of Figure 8 except that in place of a metal reinforcing interleaf of a simple inclined form, each interleaf 91 comprises a plurality of inclined portions as provided by a plate of substantially zig-zag or corrugated shape in crosssection. As in the Figure 8 construction the reinforcing interleaf results in asymmetry about a median plane.

In the Figure 10 construction an elastomeric mounting 100 comprises a pair of elastomeric bearing elements 101 in which end faces of the elastomeric material have rigid metal end plates 102,103 bonded thereto. These plates in turn are secured e g by welding to the upper and lower rigid end members 104,105. The rigid end member 103 at a lower end of each bearing element is of a corrugated form comprising four inclined surface portions whereas the end member 102 at the upper end of each bearing element is of a rigid form comprising just two inclined portions; accordingly each bearing element is of an asymmetric construction about a median plane by virtue of the difference in profiles of the respective end members of each bearing element. The end members of the bearing elements may be integral with one another (as shown in Figure 10) or may be separate, and for example may be arranged to abut one another in a side-by-side manner when in situ between the rigid end members.

8.

Claims

CLAIMS:-

1. An elastomeric mounting comprising a pair of rigid end members which def ine a pair of confronting surfaces, said surf aces being maintained spaced apart by interposed resilient elastomeric material, the elastomeric material being provided by at least two discrete elastomeric bearing elements each arranged to extend between said parallel with one another resiliently to resist relative movement of the end members in a normal direction generally perpendicular relative to said confronting surfaces and which tends to move the members towards and away from one another, and each said elastomeric bearing element having a thickness of at least 50 mm as considered in said normal direction.

2. An elastomeric mounting according to claim 1 wherein each said confronting surface is effectively planar as hereinbefore defined.

3. An elas;-omeric mounting according to claim 1 or claim 2 wherein at least one of the confronting surfaces is truly flat.

4. An elastomeric mounting according to claim 1 or claim 2 wherein at least one of the confronting surfaces is profiled in a balanced manner whereby locally induced sideways components of force acting on an elastomeric bearing element in a direction perpendicular to said normal direction are balanced for that element.

5. An elastomeric mounting according to any one of the preceding claims wherein at least one of the elastomeric bearing elements is secured directly to at least one of the end members.

6. An elastomeric mounting of claims 1 to 4 wherein at bearing element has at least end members and to act in according to any one least one elastomeric one end f ace member of substantially rigid material secured thereto, said end face member being secured to one of said rigid end members.

S 1 9.

7. An elastomeric mounting according to claim 6 wherein said end face member is of a truly planar form.

8. An elastomeric mounting according to claim 6 wherein said end face member is profiled in a balanced manner whereby locally induced sideways components of force on an individual elastomeric bearing element are balanced for that element.

9. An elastomeric mounting according to any one of the preceding claims wherein at least one of the elastomeric bearing elements is asymmetric about a median plane lying mid-way between confronting surfaces of the rigid end members.

10. An elastomeric mounting according to claim 9 wherein said asymmetry exists by virtue of a difference between the shape of end faces of the elastomer.ic bearing element.

11. An elastomeric mounting according to claim 9 or claim 10 wherein said asymmetry arises from the elastomeric material of a bearing element beJng of non-uniform cross-section to vary differently at respective sides of a median plane.

12. An elastomeric mounting according to any one of claims 9 to 11 wherein said asymmetry arises by provision of an interleaf of reinforcing material within the elastomeric material of a bearing element.

13. An elastomeric mounting according to any one of the preceding claims in which the thickness of each elastomeric bearing element is at least 75 mm in said direction of normal loading.

14. An elastomeric mounting according to any one of the preceding claims wherein said at least two bearing elements lie in close proximity to one another.

15. An elastomeric mounting according to any one of the preceding claims wherein the volume of elastomeric material in each bearing element is less than 7.5 litres.

16. An elastomeric mounting according to claim 15 wherein the volume is less than 5 litres.

c 10.

17. An elastomeric mounting according to any one of the preceding claims wherein the cross-sectional area of each elastomeric bearing element at the median plane does not exceed 0.1 square metres.

18. An elastomeric mounting according to claim 17 wherein said area does not exceed 0.05 square metres.

19. An elastomeric mounting according to any one of the preceding claims wherein the cross-sectional area of the median plane lies in the range 0. 2 to 2. 0 times the thickness of the element.

20. An elastomeric mounting according to claim 18 the cross-sectional area lies in the range 1.0 times the thickness of the element.

wherein 0. 3 to 21. An elastomeric mounting according to any one of the preceding claims wherein each bearing element is formed of an elastomeric material having a hardness in the range 35 to 70 Shore A.

22. An elastomeric mounting constructed and arranged substantially as hereinbefore described with reference to Figures 1 to 3, Figures 4 and 5, Figures 6 and 7 or Figure 8 or Figure 9 or Figure 10 of the accompanying drawings.

t 11 AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWS CLAIMS:- An elastomeric mounting comprising a pair of rigid end members which def ine a pair of confronting surfaces each of which is effectively planar as hereinbefore defined, said surfaces being maintained spaced apart by interposed resilient elastomeric material, the elastomeric material being provided by at least two discrete elastomeric bearing elements each arranged to extend between said end members and to act in parallel with one another resiliently to resist relative movement of the end members in a normal direction generally perpendicular relative to said confronting surfaces and which tends to move the members towards and away from one another, and each said elastomeric bearing element having a thickness of at least 50 mm, as considered in said normal direction.

2. An elastomeric mounting according to claim 1 wherein at least one of the confronting surfaces is truly flat.

3. An elastomeric mounting according to claim 1 wherein at least one of the confronting surfaces is profiled in a balanced manner whereby locally induced sideways components of force acting on an elastomeric bearing element in a direction perpendicular to said normal direction are balanced for that element.

4. An elastomeric mounting according to any one of the preceding claims wherein at least one of the elastomeric bearing elements is secured directly to at least one of the end members.

5. An elastomeric mounting according to any one of claims 1 to 3 wherein at least one elastomeric bearing element has at least substantially rigid material end face member being secured end members.

6. An elastomeric mounting according to claim 5 wherein said end face member is of a truly planar form.

7. An elastomeric mounting according to claim 5 one end f ace member of secured thereto, said to one of said rigid 1 IL wherein said end face member is profiled in a balanced manner whereby locally induced sideways components of force on an individual elastomeric bearing element are balanced for that element.

8. An elastomeric mounting according to any one of the preceding claims wherein at least one of the elastomeric bearing elements is asymmetric about a median plane lying mid-way between confronting surfaces of the rigid end members.

9. An elastomeric mounting according to claim 8 wherein said asymmetry exists by virtue of a difference between the shape of end faces of the elastomeric bearing element.

10. An elastomeric mounting according to claim 8 or claim 9 wherein said asymmetry arises from the elastomeric material of a bearing element being of non-uniform cross-section to vary differently at respective sides of a median plane.

11. An elastomeric mounting according to any one of claims 8 to 10 wherein said asymmetry arises by provision of an interleaf of reinforcing material within the elastomeric material of a bearing element.

12. An elastomeric mounting according to any one of the preceding claims in which the thickness of each elastomeric bearing element is at least 75 mm in said direction of normal loading.

13. An elastomeric mounting according to any one of the preceding claims wherein said at least two bearing elements lie in close proximity to one another.

14. An elastomeric mounting according to any one of the preceding claims wherein the volume of elastomeric material in each bearing element is less than 7.5 litres.

15. An elastomeric mounting according to claim 14 wherein the volume is less than 5 litres.

16. An elastomeric mounting according to any one of the preceding claims wherein the cross-sectional area of each elastomeric bearing element at the median A 1 1 G - plane does not exceed 0.1 square metres.

17. An elastomeric mounting according to claim 16 wherein said area does not exceed 0.05 square metres.

18. An elastomeric mounting according to any one of the preceding claims wherein the cross-sectional area of the median plane lies in the range 0. 2 to 2. 0 times the thickness of the element.

19. An elastomeric mounting according to claim 17 wherein the crosssectional area lies in the range 0.3 to 1.0 times the thickness of the element.

20. An elastomeric mounting according to any one of the preceding claims wherein each bearing element is formed of an elastomeric material having a hardness in the range 35 to 70 Shore A.

21. An elastomeric mounting constructed and arranged substantially as hereinbefore described with reference to Figures 1 to 3, Figures 4 and 5, Figures 6 and 7 or Figure 8 or Figure 9 or Figure 10 of the accompanying drawings.

JRB/ML - PY 10584 Published 1991 atThe Patent Office, Concept House, Cardiff Road, Newport, Gwent NP9 1P.H. Further copies may be obtained from Sales Branch. Unit 6. Nine Mile Point. Cwmfellnfach. Cross Keys. Newport. N P I 7HZ. Printed by Multiplex techniques lid, St Mary Cray. Kent.