GB2484681A

GB2484681A - A vibration damper for an auxillary machine and battery of a vehicle and method of reducing vibration

Info

Publication number: GB2484681A
Application number: GB1017630.3A
Authority: GB
Inventors: James Hawkings; Philip Guest; Peter Hawkings; Dave Hird; Joseph JOYCE
Original assignee: Land Rover UK Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2010-10-19
Filing date: 2010-10-19
Publication date: 2012-04-25
Anticipated expiration: 2030-10-19
Also published as: GB2484681B; GB201017630D0

Abstract

In a vehicle an auxiliary machine 13 such as an air compressor is physically associated with the vehicle battery 12. The battery 12 provides for substantial additional mass which resists transmission of noise and vibration from the small machine 13 to the vehicle structure 11. The small machine 13 may itself form part of a battery clamp arrangement 17. A vibration damper comprises a tray 15 which provides a mount for the auxiliary machine 13 and battery 12, and a resilient mount 14 disposed between the tray and the vehicle structure 11. The vibration damping arrangement may also include resilient snubbers 16.

Description

Vibration Damper of a Vehicle and Method of Reducing Vibration This invention relates to a vibration damper of a motor vehicle, and particularly to a vibration damper for a small machine of such a vehicle.

Conventionally a motor vehicle has an internal combustion engine, and a battery for starting the engine and powering electrical equipment of the vehicle. The vehicle may also be provided with one or more small auxiliary machines associated with the vehicle and separately mounted on the vehicle structure. Such machines typically operate intermittently on demand, or are otherwise not directly associated with normal operation of the vehicle engine.

Examples of auxiliary machines are electrically driven compressors/pumps (e.g. for air conditioning and air suspension systems), and brake modulators. These machines, whilst being small compared with the vehicle engine, can impart significant noise and vibration through the vehicle structure, which cannot sufficiently be attenuated in a cost-effective manner.

As a partial solution, the small machine(s) may be mounted resiliently in order to insulate the vehicle structure, and/or may be mounted to a very stiff portion of the vehicle structure so that the structure resists transmission of noise and vibration. These solutions are not particularly effective, and the latter can require additional material to strengthen a mounting region.

An object of this invention is to reduce such noise and vibration towards the point where it is no longer apparent to an occupant of the vehicle.

According to a first aspect of the present invention there is provided in combination a vehicle battery and a mounting for a small machine of a vehicle, the combination further including a resilient support for attachment to a vehicle structure.

The invention provides for the mass of the vehicle battery, typically greater than 15 kg, to be associated with the small machine (typically 2-5kg) so as to substantially increase the effective mass thereof, the combined mass being supported by the resilient means thereby to reduce the level of noise and vibration transmitted to the vehicle structure.

Preferably the mass ratio of small machine and battery is greater than 1:3, and preferably greater than 1:5.

The vehicle battery acts both to increase the effective mass which must be excited by the vibration source, and may also act as a damper for vibrations by virtue of the somewhat resilient nature thereof, and the fluid constituents in the form of a liquid or a gel.

In one embodiment the mounting for the small machine is substantially rigid with the battery, may be integrated with the battery, and in particular forms part of the casing of the battery.

The mounting may comprise the battery casing. In this embodiment the small machine may be mounted in use directly to the mounting, or indirectly via a resilient isolator. The isolator typically comprises a spring or springs of any suitable form, and may further incorporate damping.

In another embodiment the mounting for the small machine is mounted to the battery via a resilient isolator. In this embodiment a support or tray of the battery may for example also comprise a support for a resilient mounting of the small machine. Such an arrangement permits first and second resilient isolators, namely that between the battery and the mounting of the small machine, and between the combination and the vehicle structure.

In a second aspect of the invention the combination further includes one or more small machines mounted on the mounting. A particular feature of the invention is that it allows the inevitable large mass of the battery to be used for the secondary purpose of reducing the level of noise and vibration from a small machine.

According to a third aspect of the invention there is provided a rigid support for a battery of a vehicle, the support being adapted to permit mounting of a small machine thereon, and having a resilient support for attachment to a vehicle structure. Such a rigid support may be in the form of a battery tray, and the resilient support may be any suitable kind of spring/damper system.

In a preferred embodiment of the invention the auxiliary machine forms part or all of the battery retaining clamp.

In this embodiment, by virtue of forming the battery clamp, the noise and vibration of the small machine must pass via the battery to the vehicle structure. Accordingly, as explained above, the battery can itself act as an isolator and/or damper of noise and vibration.

In one embodiment the small machine is mounted on top of the battery and is part of the clamping arrangement which secures the battery to an undertray or the like. The small machine may comprise a top frame having screw-threaded fasteners for connection to the supporting structure beneath the battery.

It will be appreciated that effective reduction of transmission of noise and vibration permits additional mounting possibilities for the small machine in the vehicle under bonnet region, in particular the combination of battery and small machine may be mounted in a less stiff structural area which, but for the invention, would otherwise have been deemed unsuitable, or which would have required stiffening by addition of material. Accordingly the invention offers the possibility of weight and cost savings, as well as packaging advantages.

The invention also provides a method of isolating vibration transmitted from a small machine through the structure of a vehicle having a battery, the method comprising the steps of physically associating the small machine with the battery via a common mounting structure, and attaching the common mounting structure to the vehicle through a resilient isolator.

The invention may further comprise a method of reducing noise and vibration from an electrically powered auxiliary machine of a vehicle having a battery, the method comprising the steps of physically associating the small machine and battery and resiliently mounting the resulting combination to the vehicle.

Several embodiment of the invention are now described by reference to the accompanying drawings in which: Fig. 1 illustrates in schematic elevation a first embodiment of the invention; Fig. 2 illustrates in schematic elevation a second embodiment of the invention.

Fig. 3 illustrates in schematic elevation a third embodiment of the invention.

Fig. 4 illustrates a prior art mounting.

In the accompanying drawings, the dimensions are illustrative and should not be taken as representative of any particular installation. Furthermore certain dimensions are exaggerated in order to better explain the invention.

Fig. 4 illustrates a tyçcaI prior arrangement of a vehicle in which the vehicle structure (11), typically the body shell, supports a battery (12) and a small machine (13). The battery and small machine are not adjacent, but positioned according to packaging and maintenance requirements -in practice they may be quite distant.

The battery is heavy, in the range 15-30kg for an internal combustion engined vehicle, and is securely mounted via a clamp arrangement (not shown). In a hybrid or range extended vehicle, the battery may be larger than a conventional lead/acid battery, and heavier. I0

The small machine (13) is typically a compressor, pump, modulator or the like, and may be fixed rigidly or resiliently. Where possible a resilient mounting (14) using or consisting of rubber is often used to minimize transmission of noise and vibration to the vehicle structure.

Fig. 1 illustrates a first embodiment in which the small machine (13) is physically associated with the battery (12) via common mounting tray (15) to which both are rigidly attached by means not shown.

The tray (15) in turn is resiliently supported on the vehicle structure (ii). This construction requires the small machine to excite the combined mass in order to generate significant noise and vibration, and in any event provides for tuneable resilient mounting which can be selected for the required frequency range and amplitude.

Typically the resilient mounting is selected to ensure that during highway driving movement of the tray (15) with respect to the structure (11) is within limits imposed by resilient snubbers (16) The snubbers however ensure that excessive travel of the tray (15) is prevented it the vehicle travels over rough terrain.

In a typical example a H8 battery has a mass of about 26kg, and an air suspension pump has a mass of 4.5kg. The resilient support (14) consists of four elastomeric mountings operating in shear and having a design rate of about 30N/mm. Total free travel between the snubbers is around 3-4mm.

Fig. 2 illustrates an alternative embodiment in which the small machine (13) is directly attached to the battery (12), the combination being mounted upon a tray (15) of the kind illustrated in Fig. 1 (snubbers not shown). The small machine may be mounted to the side, or above (dotted outline) where it forms part of the usual battery clamp arrangement (17).

This latter arrangement permits the cost and weight of the conventional battery clamp to be reduced.

In the arrangement of Fig. 3, the small machine (13) or the mounting thereof is attached to the tray (or battery) via a second resilient mount (18). This arrangement provides for further damping or isolation, and for a small machine of about 4.5kg may consist of three metal coil compression springs having 3-4mm float between snubbers (not shown), and a rate of 5.7 N/mm.

Adjustment of spring rates and the provision of additional damping is within the ordinary skill of an appropriately educated engineer, taking into account the nuisance frequencies and the component mass(es). The invention provides an inexpensive means of substantially reducing noise and vibration, can result in material and weight savings of the vehicle structure and can also eliminate somewhat expensive treatment of noise and vibration by additional isolation and sound proofing materials.

The invention may also increase battery life by protecting the battery from vibrations transmitted to it via the vehicle structure, such as those generated by the vehicle engine and road suspension at key frequencies. The invention is particularly effective at frequencies above 20Hz.

In the case of a hybrid vehicle, when running in electric motor mode, the mass of the battery can very substantially reduce transmission of noise and vibration to the passenger cell.

Claims

Claims 1. In physical combination, a vehicle battery and small machine, the combination further including a resilient support for attachment to a vehicle structure.
2. The combination of claim 1, wherein the battery and small machine are attached to a tray, and said resilient support bears upon the tray.
3. The combination of claim 2, wherein the small machine and battery are rigidly attached to said tray.
4. The combination of claim 3, wherein the small machine and battery are in physical contact.
5. The combination of any preceding claim, wherein the small machine comprises a battery clamp.
6. The combination of claim 6, wherein the small machine overlies the battery.
7. The combination of any of claims 1-5, wherein the small machine and battery are side by side.
8. The combination of claim 2, wherein the small machine is resiliently supported on said tray.
9. The combination of claim 8, wherein the small machine and battery are side by side.
10. The combination of any preceding claim, wherein the small machine is an electrically powered pump.
11. A vehicle incorporating the combination of any of claims 1-10.
12. A vehicle according to claim 11, wherein the combination is directly attached to the body shell thereof via said resilient support.
13. A method of reducing noise and vibration from an auxiliary machine of a vehicle having a battery, the method comprising the steps of physically associating the small machine and battery, and resiliently mounting the combination of small machine and battery to a vehicle.
14. ln physical combination a vehicle battery and a small machine, substantially as described herein with reference to Figs. 1-3 of the accompanying drawings.
15. A method of reducing noise and vibration substantially as described herein with reference to the accompanying drawings.