GB2334245A

GB2334245A - Noise absorption in vehicle steering gear

Info

Publication number: GB2334245A
Application number: GB9825770A
Authority: GB
Inventors: Roland John Hayward
Original assignee: MG Rover Group Ltd
Current assignee: MG Rover Group Ltd
Priority date: 1998-02-12
Filing date: 1998-11-26
Publication date: 1999-08-18
Anticipated expiration: 2018-11-26
Also published as: GB9802964D0; GB2334245B; GB9825770D0

Abstract

A valve housing 6 of a vehicle power steering gear is enclosed in a layer 8 of noise absorbing material which extends over its top end and down its sides to its base where it joins the steering rack housing. The top of the layer of noise absorbing material is held in light compression against the firewall 2 through which the steering gear pinion 3 extends thereby forming a seal between the firewall 2 and the valve housing 6.

Description

VEHICLE STEERING GEAR The present invention relates to vehicle steering noise abatement and more particularly to such noise abatement in rack and pinion type steering mechanisms.

With the ever-increasing requirement to improve refinement, comfort and performance within motor vehicles, noise abatement has remained a relevant issue. Generally, it is passenger received noise which is more important to the manufacture whilst external noise is typically controlled by legislative limits.

A vehicle panel can be sound deadened by application of an appropriate material but openings and orifices through that panel can create significant problems.

A major sound tunnel within a motor vehicle is from the steering mechanism through an orifice in the vehicle body. The significance of this sound pathway is that it leads generally to the passenger cabin and so creates noise problems for the manufacturer in terms of comfort for passengers within that cabin.

In accordance with the present invention there is provided a vehicle steering assembly comprising a valve housing at least partially enclosed in a layer of vibration absorbing material, and a rotatable input shaft protruding from an end of the valve housing, wherein the shaft is arranged to extend through an aperture in a vehicle panel member and the vibration absorbing material covering said end of the valve housing is arranged to contact the panel around the aperture to form a seal between the valve housing and the panel.

The vibration absorbing material may be attached to the valve housing by means of adhesive which forms a seal between them.

Preferably the vibration absorbing material is under slight compressive engagement about said aperture of the panel to ensure retention of the seal about said panel despite configurational variation between said seal and said panel.

Preferably the vibration absorbing material extends down the sides of the valve housing substantially to its base where it is joined to a steering rack housing.

Preferably the valve housing has ports through which hydraulic pipes are connected to it and the vibration absorbing material covers the ports.

An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawing illustrating in side cross-section a sound deadening arrangement.

Referring to the drawing, a steering mechanism 1 is arranged within a motor vehicle such that a portion of the mechanism, the steering gear pinion 3, extends through an aperture 7 in a panel 2 which forms the firewall defining the front of the passenger compartment. The steering gear pinion 3 extends from a steering gear valve element including a housing 6 which houses valves which are operated by rotation of the pinion 3 to control the power steering by controlling the flow of fluid through the steering gear pipes 6a, 6b connected to respective ports in the valve housing. The valve element is of a greater diameter than the pinion 3 and its upper end therefore forms a shoulder 10 parallel to the panel 2 but spaced from it. The steering gear pinion 3 is of a smaller diameter than the aperture 7.

A shroud of noise and vibration absorbing material 8 encloses the valve housing 6, extending over the shoulder 10 at its top end, and down its sides towards its base where it joins the steering rack housing 11. This shroud is made up of a relatively hard inner layer 5 and a thicker, relatively soft, outer layer 4.

The top part of the shroud 8 also is in contact with the panel 2 around the aperture 2 and therefore forms a seal or plug preventing the transmission of noise through the aperture 7 into the passenger compartment.

The outer layer 4 of the shroud may be a non-woven fabric or a foam material.

In order to ensure adequate waterproofing it is normal to provide an environmental seal about the pinion 3 to prevent ingress of water through the aperture 7 into the passenger compartment. Such an environmental seal may be provided by an 0 ring arrangement 9 located about the pinion 3 or alternatively the top part of the shroud 8 may be sealed onto the shoulder 10 of the valve element using an adhesive or mastic type coating therebetween.

It will be understood by those skilled in the art that despite the best efforts of a designer there will be dynamic and potentially static variations between the panel 2 and the steering mechanism 1 in terms of configuration. In terms of noise abatement it is movement in the direction of the arrow heads 12 which is of most importance. It will be understood that if the top of the shroud 8 became disengaged from the panel 2 an air gap would be created through which both noise and water etc. might pass.

Conversely, if the shroud 8 and the panel 2 became into too great a compressive engagement then the sound absorption effect of those portions of the shroud 8 which engage the surround of aperture 7 would be reduced.

Thus, in an ideal situation the seal 8 would be under slight compressive engagement with the panel 2 and there would be a sufficient depth in the top portions of the shroud 8 to provide a relatively wide range of deformation before sound deadening functions significantly attenuated. In order to anchor the shroud 8 in such a slight compressive engagement with the panel 2 the valve element 6 can be used as locating "keys" upon which such anchoring can take place.

The shroud 8 could be directly moulded onto the mechanism 1. The sound deadening material 1 would thereby be attached directly to the mechanism 1 without the need for separate sealing using "0" rings, etc., and a reduce requirement for manual assembly.

Claims

CLAIMS 1. A vehicle steering assembly comprising a valve housing at least partially enclosed in a layer of vibration absorbing material, and a rotatable input shaft protruding from an end of the valve housing, wherein the shaft is arranged to extend through an aperture in a vehicle panel member and the vibration absorbing material covering said end of the valve housing is arranged to contact the panel around the aperture to form a seal between the valve housing and the panel.
2. An assembly as claimed in claim 1, wherein the vibration absorbing material is attached to the valve housing by means of adhesive which forms a seal between them.
3. An assembly as claimed in claim 1 or claim 2, wherein the vibration absorbing material is under slight compressive engagement about said aperture of the panel to ensure retention of the seal about said panel despite configurational variation between said seal and said panel.
4. An assembly according to any foregoing claim wherein the vibration absorbing material extends down the sides of the valve housing substantially to its base where it is joined to a steering rack housing.
5. An assembly according to any foregoing claim wherein the valve housing has ports through which hydraulic pipes are connected to it and the vibration absorbing material covers the ports.
6. An assembly according to any foregoing claim wherein the panel is a firewall defining the front of a passenger compartment of the vehicle.
7. A sound deadening arrangement substantially as hereinbefore described with reference to the accompanying drawings.