TITLE: Vibration Damping Device

Technical Field

The present invention relates to a vibration damping device.

The invention has been developed for use in reducing noise generated by vibration in wheels, such as in driving and idler wheels in tracked earthmoving vehicles and tracked military-type vehicles, rail bogey wheels, and gear wheels, and will be described hereinafter with reference to these applications. However, the present invention may also be used wherever wheels are used or where vibration is sought to be damped, for example in mechanical or structural engineering applications.

Background of the Invention

Tracked earthmoving vehicles, such as dozers, generate track noise, which is commonly referred to as "track clatter". This noise originates from a combination of sources, including, track-on-drive-sprocket, track-on-idler-wheel, track-on-support rollers, and track-on-track. One specific area contributing to the noise generation is the "ring" of idler wheels when impacted by the track. Other wheeled equipment also suffer from adverse noise generation, particularly where the wheels have an acoustic shape. Such wheels include rail bogey wheels and gear wheels.

The noise generated by such wheels can be significant and poses an occupational health and safety risk to vehicle operators, as well as contributing to noise pollution of the surrounding environment.

Known methods of reducing wheel noise include the use of wheel web stiffeners and damping rings fixed in various ways to wheel webs. For example, US Patent No. 1,695,529 discloses a damping ring system.

A disadvantage of known wheel vibration damping systems is that they are difficult to install and/or reduce the operational efficiency of the device with which they are used. Moreover, known vibration damping systems damp a relatively narrow spectrum of vibration frequencies and are also difficult to tune to the particular harmonics of a given

wheel. Also, many known wheel damping systems provide inadequate damping for the whole wheel, such that some portions of the wheel are still free to resonate.

Object of the Invention

It is the object of the present invention to substantially overcome or at least ameliorate 5 one or more of the above disadvantages.

Summary of the Invention

Accordingly, in a first aspect, the present invention provides a vibration damping device comprising: a strut adapted to extend between a first surface and a second surface fixed relative o to the first surface; a first damper connected to one end of said strut and adapted for engagement with said first surface; a bearing surface on an opposite end of said strut and adapted for engagement with said second surface; s an adjustment mechanism between said bearing surface and said first damper for adjusting the distance therebetween.

The first and second surfaces are preferably, respectively, a rim and a hub of a wheel.

o The bearing surface is preferably provided on a second damper connected to the opposite end of said strut. The first and second dampers are preferably formed from an elastomeric material. The elastomeric material is preferably adapted to damp a broad range of vibration frequencies. The elastomeric material is preferably polyurethane. However, other elastomeric materials can alternatively be used. The dampers can also be 5 hollow, air impregnated, cored, laminated or complex in structure.

The first damper preferably has a convex end surface for engaging a curved inner surface of the rim. The second damper preferably has a concave end surface for engaging a curved surface of the hub. The first and second dampers preferably have side surfaces for 0 engaging a wheel web extending between said hub and said rim.

The adjustment mechanism is preferably adapted to allow the vibration damping device to be tuned to the harmonics of the wheel. The adjustment mechanism preferably includes a nut engaged with a threaded portion of said strut, the first damper preferably being engageable by said nut.

In a second aspect, the present invention provides a structure adapted for vibration damping, said structure comprising: a first surface; a second surface fixed with respect to said first surface; a strut extending generally radially between said first surface and said second surface; a first damper connected to one end of said strut and engaged with said first surface; a bearing surface on an opposite end of said strut and engaged with said second surface; and an adjustment mechanism between said bearing surface and said first damper for adjusting the distance therebetween.

The first and second surfaces are preferably, respectively, a rim and a hub of a wheel.

The bearing surface is preferably provided on a second damper connected to the opposite end of said strut. The first and second dampers are preferably formed from an elastomeric material. The elastomeric material is preferably adapted to damp a broad range of vibration frequencies. The elastomeric material is preferably polyurethane. However, other elastomeric materials can alternatively be used. The dampers can also be hollow, air impregnated, cored, laminated or complex in structure.

The adjustment mechanism is preferably adapted to allow the wheel vibration damping device to be tuned to the harmonics of the wheel. The adjustment mechanism preferably includes a nut engaged with a threaded portion of said strut, the first damper preferably being engageable by said nut.

Preferably, a plurality of the wheel vibration damping devices are provided. The adjustment mechanisms of the wheel vibration damping devices are preferably independently adjustable. The wheel vibration damping devices are preferably

symmetrically disposed about said hub. The wheel vibration damping devices are preferably provided in multiples of two. In some embodiments, the rim extends on both sides of the web and a plurality of the vibration damping devices are provided on each side of the web.

A plate preferably extends over said wheel vibration damping devices. The plate is preferably annular and extends between said hub and said rim. The first and second dampers preferably have outer side surfaces for engaging said plate.

Brief Description of the Drawings Preferred embodiments will now be described, by way of examples only, with reference to the accompanying drawings, in which:

Fig. IA is a schematic cross-sectional front elevational view of a preferred embodiment of a vibration damping device;

Fig. IB is a schematic cross-sectional side elevational view of the vibration damping device of Fig. IA;

Fig. 2 is a side elevational view of a first embodiment dozer idler wheel;

Fig. 3 is a cross sectional view taken along line 3-3 of Fig. 2;

Fig. 4 is a side elevational view of a second embodiment dozer idler wheel;

Fig. 5 is a cross sectional view taken along line 5-5 of Fig. 4; Fig. 6 is a side elevational view of a third embodiment dozer idler;

Fig. 7 is a cross sectional view taken along line 7-7 of Fig. 6;

Fig. 8 is a side elevational view of a fourth embodiment dozer idler wheel;

Fig. 9 is a cross sectional view taken along line 9-9 of Fig. 8;

Fig. 10 is a side elevational view of a first embodiment rail bogey wheel; Fig. 11 is a cross sectional view taken along line 11-11 of Fig. 10;

Fig. 12 is a side elevational view of a second embodiment rail bogey wheel;

Fig. 13 is a cross sectional view taken along line 13-13 of Fig. 12;

Fig. 14 is a side elevational view of a first embodiment gear wheel;

Fig. 15 is a cross sectional view taken along line 15-15 of Fig. 14; Fig. 16 is a side elevational view of a second embodiment gear wheel; and

Fig. 17 is a cross sectional view taken along line 17-17 of Fig. 16.

Detailed Description of the Preferred Embodiments

Figs. 1 A and IB show a preferred embodiment of a vibration damping device 10. The device 10 is adapted for use with a wheel comprising a hub, a rim and a web extending therebetween. The device 10 includes a strut 12 adapted to extend generally radially between the hub and the rim. A first damper 14 is connected to one end of the strut 12 and has a convex end bearing surface 16 adapted for engagement with the rim. A second damper 18 is provided at an opposite end of the strut 12 and has a concave end bearing surface 20 adapted for engagement with the hub. The first 14 and second 18 dampers have side surfaces 22, generally perpendicular to the end bearing surfaces 16, 20, for engaging the wheel web.

An adjustment mechanism, comprising a nut 24 attached to a threaded portion of the strut 12, is provided between the first damper 14 and the second damper 18. The nut 24 is engageable with the first damper 14 to adjust the distance between the first damper 14 and the second damper 18 and thereby to vary the force applied between the first damper 14 and the rim, and between the second damper 18 and the hub.

The selection of damper material is the first step to determining the vibration damping characteristics of the device 10. Depending on the particular application, softer damper materials can be used to damp a broad range of vibration frequencies, or alternatively, harder damper materials can be used to target more specific vibration frequencies. In the illustrated embodiment, the first 14 and second 18 dampers are formed from solid polyurethane and damp a broad spectrum of vibration frequencies. The adjustment mechanism also allows the wheel vibration damping device 10 to be tuned to the harmonics of the wheel by varying the distance between the dampers 14, 18 and thereby varying the force applied between the dampers 14, 18 and the hub and rim until the wheel ceases to resonate.

Figs. 2-17 show preferred embodiments of wheels 30, each having a hub 32, rim 34 and web 36, to which are connected various configurations of vibration damping devices 10 as described above with reference to Fig. IA and IB. As shown, the vibration damping devices 10 are provided in multiples of four.

Figs. 2 and 3 show a dozer idler wheel 30 including four vibration damping devices 10 symmetrically disposed about the wheel hub 32. The adjustment mechanisms (i.e. nuts 24) of the vibration damping devices 10 are independently adjustable. The convex end surface 16 of the first damper 14 engages the rounded inner surface of the wheel rim 34. Likewise, the concave end surface 20 of the second damper 18 engages the wheel hub 32. Also, the side surfaces 22 of the dampers 14, 18 engage the wheel web 36. Engagement of the dampers 14, 18 with the hub 32, rim 34, and web 36 damps the vibration of these components and thereby reduces noise.

Figs. 4 and 5 show a dozer idler wheel 30 similar to that shown in Figs. 2 and 3, but with four vibration damping devices 10 on each side of the wheel web 36.

Figs. 6 and 7 show a dozer idler wheel 30 similar to that shown in Figs. 2 and 3, but with eight vibration damping devices 10 on each side of the wheel web 36.

Figs. 8 and 9 show a dozer idler wheel 30 similar to that shown in Figs. 4 and 5, but further comprising annular plates 38 bolted to the web 36 and extending over the vibration damping devices 10 between the hub 32 and the rim 34. Outer side surfaces 40 of the dampers 14, 18, which extend generally perpendicular to the end surfaces 16, 20, engage the plates 38 to damp vibration of the plates 38 and thereby reduce noise.

Figs. 10 and 11 show a rail bogey wheel 30 including four vibration damping devices 10 symmetrically disposed about the wheel hub 32. The adjustment mechanisms (i.e. nuts 20) of the vibration damping devices 10 are independently adjustable. The convex end surface 16 of the first damper 14 engages the rounded inner surface of the wheel rim 34. Likewise, the concave end surface 20 of the second damper 18 engages the wheel hub 32. Also, the side surfaces 22 of the dampers 14, 18 engage the wheel web 36. Engagement of the dampers 14, 18 with the hub 32, rim 34 and web 36 damps the vibration of these components and thereby reduces noise.

Figs. 12 and 13 show a rail bogey wheel 30 similar to that shown in Figs. 10 and 11, but further comprising an annular plate 38 bolted to the web 36 and extending over the vibration damping devices 10 between the hub 32 and the rim 34. Outer side surfaces 40

of the dampers 14, 18, which extend generally perpendicular to the end surfaces 16, 20, engage the plates 38 to damp vibration of the plates 38 and thereby reduce noise.

Figs. 14 and 15 show a gear wheel 30 including four vibration damping devices 10 symmetrically disposed about the wheel hub 32. The adjustment mechanisms (i.e. nuts 24) of the vibration damping devices 10 are independently adjustable. The convex end surface 16 of the first damper 14 engages the rounded inner surface of the wheel rim 34. Likewise, the concave end surface 20 of the second damper 18 engages the wheel hub 32. Also, the side surfaces 22 of the dampers 14, 18 engage the wheel web 36. Engagement of the dampers 14, 18 with the hub 32, rim 34 and web 36 damps the vibration of these components and thereby reduces noise.

Figs. 16 and 17 show a gear wheel 30 similar to that shown in Figs. 14 and 15, but further comprising an annular plate 38 bolted to the web 36 and extending over the vibration damping devices 10 between the hub 32 and the rim 34. Outer side surfaces 40 of the dampers, which extend generally perpendicular to the end surfaces 16, 20, engage the plate 38 to damp vibration of the plate 38 and thereby reduce noise.

An advantage of the illustrated vibration damping devices 10 is that they are relatively easy to retrofit on existing wheels and generally require no modification of the wheel prior to installation. Another advantage is that the elastomeric material from which the dampers are formed provides for broad spectrum vibration damping, thereby reducing the need to tune the devices 10. However, if required, accurate tuning can be achieved due to the damping devices 10 being independently adjustable. A further advantage is that the vibration damping devices 10 damp the entire wheel, as the dampers 14, 18 engage the wheel hub 32, rim 34 and web 36. Yet another advantage is that the annular plates 38 protect the vibration damping devices 10 from damage and also safeguard against personnel tampering with or being injured by the devices 10.

Whilst the invention has been described with reference to specific embodiments, it will be appreciated that it may also be embodied in many other forms. For example:

• The threaded nut 20 adjustment mechanism can be replaced with a pneumatic system, a wedge system or a spring system for adjusting the spacing between the first damper 14 and the second damper 16;

• Additional intermediate dampers can be provided along the length of the strut 12;

• The dampers 14, 18 can be configured to engage only one or two of the hub 32, rim 34, and web 36;

• The dampers 14, 18 can be provided at discrete locations as illustrated, or can be provided as manifolds extending completely around the wheel hub 32 and/or rim

34;

• hi the illustrated embodiments, the nuts 24 are held in place by reaction loading of the dampers 14, 18. However, in other embodiments, the nuts 24 are welded in position on the threaded portion of the strut 12; • The end bearing surfaces 16, 20 of the dampers 14, 18 can be flat and can deform to conform to the shape of the associated wheel hub 32 or rim 34;

• The dampers 14, 18 can be formed from other elastomeric materials, such as rubber;

• The dampers 14, 18 can be hollow, air impregnated, cored, laminated or complex in structure;

• Where annular plates 38 are provided on opposite sides of the web 36, the plates 38 can be connected to each other through holes (not shown) in the web 36;

• The device 10 can also be used to dampen vibration in structural beams (not shown) by installing the device 10 between beam flanges.