SINGLE-PIECE MOUNT WITH SPLIT METAL PLATES

Abstract: A single-piece elastomeric mount (22) installed over a plurality of openings (15) has a like plurality of reinforcing plates (44 and 46) to permit the elastomeric rib between the plates' edges to flex. The apertures (24 and 26) in the mount can then be aligned with holes (15) in a support (13) having wider tolerances on their end positions. The mount may include two sets of plates - an upper load-distribution set (44 and 46) and a lower wear-reducing set (30 and 32), each set being bonded to the elastomer.

Description: SINGLE-PIECE MOUNT WITH SPLIT METAL PLATES Background and Summary ofthe Invention This invention relates to the field of elastomeric mounts. More particularly, the present invention is directed to a mount having split plates which increase wear resistance while permitting flexing of the mount to permit variations in the support plate's hole spacing to be accommodated. A concern arose regarding the wear life of a bushing mount being used to support a diesel truck engine. The mount is a cylindrical center-bonded bushing or grommet-style mount which was used in a flanged support that is formed as a casting. A small diameter portion of the mount (the "shank") extends through a hole formed in the support while a larger diameter portion (the "head") rests on the surface of the support. The lower surface of the head was experiencing considerable wear as a result of the vibration-induced movement between that surface and the rough cast surface of the support. In addition, test parts developed significant cracks at the transition point between the shank and the head. Further the upper surface of the head offered minimal surface area through which to react loads. The present invention seeks to remedy whichever one of these problems is most serious for a particular application by extending the mount to reach between at least two holes in the supporting member and incorporating a metallic plate into the upper or lower surface to reduce wear. A problem arose when a single plate was provided that extended between the two holes: in forming the casting, dowel rods are used to position the grommet-receiving holes in the support. As the molten metal is poured into the casting, the dowel rods can be caused to move within a Umited range of positions resulting in non-uniformity in the center hole spacing in the support. The lack of flexibility in the mount caused by the wear-reducing plate necessitated the customer to assume the additional expense of machining their part to provide a more uniform hole spacing or resulted in even greater additional costs associated with discarding out-of-spec castings. To resolve this problem, the flexibility of the present mount is enhanced by subdividing the reinforcement plate(s), with each fastener- receiving aperture being provided with its own wear-reducing and/or load distributing plate. The elastomer between the surface plates serves as a flexible spine or rib enabling the center-to-center spacing of the apertures to be flexed to accommodate the out-of-spec hole spacing in the support. The upper load-distributing plates significantly increase the surface area which engages the supported member thereby more widely distributing the load. For this particular application, it is preferred that each aperture be provided with a set of both upper load-distributive plates and a set of lower wear-reducing plates, but some applications may require only one of these sets of plates. Various other features, advantages and characteristics of the present invention will become apparent after a reading of the following specification. Brief Description of the Drawings The drawings depict the preferred embodiments of the present invention, like items bearing like reference numerals in which FIG. 1 is side view in partial cross section of a first embodiment of the elastomeric mount of the present invention; FIG. 2A is a top view ofthe embodiment depicted in Fig. 1; FIG. 2B is a bottom view of the Fig. 1 embodiment; FIG. 3 is a cross-sectional side view of a portion of the mount of the present invention shown in its installed position; and FIG. 4 is a top view of a second embodiment of the present invention. Detailed Description of the Preferred Embodiments A first embodiment of the elastomeric mount of the present invention is depicted in Fig. 1 generally at 20. A first fastener -receiving aperture 24 extends through an elastomeric layer 22 and is preferably lined by a center- bonded metallic sleeve 28. A second fastener receiving aperture 26 also extends through the elastomeric layer 22 and is lined by a second sleeve (not shown). Although the mount 20 of this design is shown as a grommet-type mount having center-bonded sleeves 28, the principles of this invention apply to other types of mounts, as well. A first set of metallic plates 30, 32 (Fig. 2B) are bonded to a lower surface 21 of elastomeric layer 22 and, indeed, the elastomer may be permitted to fill the recess 34 created when central throughbore 36 is formed by extruding collar 38. An elastomeric boot 40 is formed by elastomer extruded between sleeves 28 and collar 38 for a purpose to be described below. Upper plates 44 and 46 (Fig. 2A) are bonded to the upper surface 23 of elastomeric layer 22 and have apertures 48 and 50 which are coaxial with apertures 24 and 26, respectively. Upper plates 44 and 46 are formed with sprue holes 42 to permit the elastomer of layer 22 to be injected into the mold (not shown) therethrough. A rib of elastomer 52 is formed between the ends of the first set of plates 30, 32 and the second set of plates 44, 46. Rib 52 permits the mount to be flexed to permit center-bonded apertures 24, 26 to accommodate variations in center-to-center spacing of holes 15 in support 13. The terminal ends of pairs of plates 30 and 44 and 32 and 46 are shown as being coplanar which is preferred, although not necessary. As best seen in Fig. 3, nut 54 is threaded onto end of bolt 56 to secure supported member 11 to support 13. Support 13 is a rough finished cast member and plates 30, 32 of the first set of plates will protect elastomeric layer 22 from abrasion caused by rubbing as the supported member, a diesel engine, for example, vibrates relative to support 13. The supported member 11 (which may for example be an engine bracket), upper plates 44, 46, sleeves 38, and washer 58 provide a sohd metallic path between the head of bolt 56 and nut 54 permitting the elastomer of boot 42 to be collapsed as shown in Fig. 3. Normally, as mount 20 receives its half of the diesel engine load (or 1300 lbs. each, two mounts 20 being used), the design of the mount will be such that a slight gap will open between boot 42 and the nether surface of support 13. This gap will enhance vibrational isolation. In any case, boot 42 serves as a rebound cushion damping upward movement of the supported member 11 which may be caused by engine torque or road bumps, for example. The present mount was tested in a test fixture against the grommet- style mount it replaced until each mount was worn out (defined as a 30% reduction in stiffness). The mount of the present invention achieved more than an 8 fold increase in wear life (221,000 cycles vs. 25,000 cycles). In addition, reduced wear on the underhead portion of the mount was experienced as a result of the presence of plates 30, 32 in spite of the additional cycles. The advantages of the present mount design are not Umited to apphcation to bushing type mounts nor to mounts having only two throughbores. A second embodiment is depicted in Fig. 4 in which mount 20' is shown having four fastener-receiving apertures 24' each having its separate plate 44'. The horizontal and vertical ribs 52' and 53' permit the aUgnment of apertures 24' to be varied to permit the mount 20' to accommodate variations in center to center spacing of apertures 15 in support 13. Obviously, the configuration shown is exemplary and not intended to be Umiting in any sense. Various changes, alternatives and modifications wdl become apparent to one of ordinary skill in the art following a reading of the foregoing specification. It is intended that aU such changes, alternatives and modifications as fall within the scope of the appended claims be considered part of the present invention.

Claims: Claims What is claimed is: 1. An elastomeric mount comprising a) a layer of elastomer; b) at least two fastener-receiving apertures extending through said elastomeric mount; c) at least one separate metallic plate for each of said at least two fastener-receiving apertures adjacent an upper or lower surface of said elastomer forming a first set of metalUc plates to provide a wear-protecting, load-distributing surface for said elastomer, each of said plates of said first set having an aperture which is coaxial with its corresponding fastener-receiving aperture in said mount and being bonded to said upper or lower elastomer surface; whereby said separate metallic plates permit flexing of said elastomeric mount enabUng a distance between said at least two fastener-receiving apertures to be adjusted to accommodate variations in hole center spacing in a supporting member to which said mount is attached. 2. The elastomeric mount of Claim 1 wherein said first set of metalUc plates are positioned adjacent said lower elastomer surface to reduce wear on said lower surface. 3. The elastomeric mount of Claim 2 further comprising a second set of separate metallic plates having apertures coaxial with each of said fastener-receiving apertures in said mount, said second set of plates being positioned adjacent said upper elastomer surface to distribute load. 4. The elastomeric mount of Claim 3 wherein each fastener- receiving aperture in said mount is Uned by a metalUc sleeve extending therethrough. 5. The elastomeric mount of Claim 4 wherein said separate metallic plates positioned adjacent said lower surface are each formed as separate stampings having a central throughbore formed by an extruded collar which receives one of said metalUc sleeves. 6. The elastomeric mount of Claim 5 further comprising a deformable elastomeric boot surrounding and extending beyond said metalUc sleeve, said elastomeric boot being deformable around a through bolt to form a rebound cushion. 7. The elastomeric mount of Claim 5 wherein a thickness of said plate from said second set and said metalUc sleeve form a fixed distance between an underneath surface of a bolt head and an opposing surface of a connected nut. 8. The elastomeric mount of Claim 7 wherein said fixed distance exceeds a thickness normally occupied by a supported member, said elastomeric mount, said supporting member, said elastomeric boot in a fully compressed position, and washer means against which said connected nut seats, whereby said elastomeric boot operates as a rebound cushion against an upward movement of said supported member relative to said supporting member. 9. The elastomeric mount of Claim 1 wherein said first set of metallic plates is are positioned adjacent and bonded to said upper elastomer surface to distribute load.

Inventors: DORTON DAVID W, DORTON, DAVID, W.
Applicants: LORD CORP, LORD CORPORATION
Application year: 1996
Main classification: F16M13
IPC codes: F16B5, F16F1