GB2134457A - Tyre-pressure regulating unit - Google Patents

Abstract

The compressed air and central air pressure pipes (7, 8) are bent to a U-shape so as to embrace the wheel between their connection to the outboard rotary manifold (6) and their securement to the axle in the region of the bearing (9). The arrangement permits simple maintenance of the rotary manifold, may be retro-fitted and is robust and reliable. <IMAGE>

Description

SPECIFICATION Tyre-pressure regulating unit for motor vehicles The invention relates to a tyre-pressure regulating unit for a motor vehicle, comprising a rigid compressed-air line connected to the vehicle, a íine arranged for rotation with the wheel, a rotary manifold which is arranged externally on the wheel rim and in alignment with the axle, and a connecting line from the rigid compressed-air line to the rotary manifold.

A unit of this type is known from the Patent Specification US 3 718 200. It has a rigid pipe compressed-air distribution system which is connected to the chassis of the vehicle. Flexible hose lines lead from the ends of this piping system to rotary manifolds each of which is installed on the wheel-rim dish or disc on the outside of the wheel in alignment with the axle. Pipe sections rotating with the wheel lead from the rotary manifold to the pneumatic tyre. Because of the large spring deflection between wheel and chassis, the flexible hose lines are subjected to considerable mechanical stress. Moreover, in this solution the rotating man if old and ducts are constantly under pressure, whereby the seals wear relatively rapidly.

Anothertyre-pressure regulating unit is known from Patent Specification DE-OS 21 41 087. Here the rotary manifold is installed on the wheel inside co-axially with the wheel axis. It comprises a stator part and a rotor part and directs the compressed air coming from a central pressure vessel to a control valve, which is fitted on the wheel rim and rotates therewith, from where it is directed to the tyre via the co-rotating line part.

Since the seals used in the rotary manifold are su bjected to not inconsiderable wear, they have to be regularly maintained or replaced. In the case of the solution proposed here, in orderto gain access to the rotary manifold it is necessary each time to dismount at least the wheel, sometimes even part of the axle itself. If the unit is fitted to a vehicle whose wheels are driven individually and therefore each have their own transmission, in particular an epicyclic gearing, it is also necessary to dismount parts of the transmission. All these operations can only be carried out in a correspondingly equipped workshop.

In other known designs, the rotary manifold is not fitted on the axle but incorporated with the compressed-air supply lines in the axle. Admittedly, space and weight are thereby saved, however, with certain dimensions this design can be installed only with difficulty.

If the rotary manifold is incorporated in the axle or transmission, inevitable negligence leads to an undesirable pressure build-up in the axle ortrans- mission housing, particularlywith increasing wear of the seals. Together with the heating up of the transmission components during operation of the motor vehicle, a pressure can thus build up which leads to fracture of the transmission cover, if a relief valve has not been additionally incorporated.

The present invention is based on the object of devising a tyre-pressure regulating unit of the type indicated initially, in which thé connecting line from the rigid compressed-air line to the rotary manifold is subjected to substantially lower stress, while at .

the same time being of simple construction, simple to install and reliable in operation.

This object is achieved in that the rigid compressed-air line is carried with the wheel axle and a U-shaped bent pipe embracing the wheel is provided for the compressed-air-supply from the axie to the rotary manifold.

Accordingly, the advantages are obtained that no relative movements occurs between the U-shaped bent pipe and the wheel apart from the rotary movement of the wheel in use of the vehicle, that service life is considerably improved, that motor vehicles with standard axles can be used without modification, that no pressure build-up has to be feared in the transmission or axle components and, above all, that motor vehicles already in service can also be equipped subsequently with this tyrepressure regulating unit.

Exhausting testing of the unit according to the invention has shown that it is very robust and that passing the pressure tube over the wheel does not involve any disadvantages in practical operation.

This is particularly the case when the rotary manifold is to be arranged protected within the wheel-rim disc and the U-shaped bent pipe is so directed that it does not extend beyond the outermost contour of the vehicle.

If a tyre-pressure regulating unit according to Patent Specification DE-OS 28 23 045 is used in which a wheel-control valve is provided mounted for rotation with the wheel, then in accordance with an advantageous development it is possible that a further U-shaped bent pipe embracing the wheel can be provided for supplying air to the valve. In this case, both tubes are preferably disposed parallel with one another.

Preferably, the or each pipe is inclined rearwards by about 40 relative to the vertical. It has been shown that with such an arrangement the clearance of the tyre is always assured even with maximum axle displacement.

If a relief or by-pass valve is also provided in addition to a wheel-control valve, the relief valve can preferably still be arranged protected within the vehicle body.

An embodiment of the invention will now be described by way of example and with reference to the accompanying drawings, of which: Figure 1 shows a side view of a motor vehicle wheel with a tyre-pressure regulating unit according totheinvention;and Figure2 shows a plan view, partly in section, of the wheel in Figure 1 with the tyre-pressure regulating unit.

Figure 1 shows a tyre 1 which is fitted on a wheel rim 2. On the rim 2 there is also mounted, for rotation with the wheel, a part of a tyre-pressure regulating unit 3 which essentially comprises a wheel-control valve 4, a valve supply line 5 and a rotary manifold 6. The rotary manifold 6 is situated externally and in alignment with the axle. The supply of compressed air and control air is effected by means of two U-shaped bent pipes 7, 8 embracing the wheel 1. The wheel 1, 2 and also the pressure pipes 7,8 are situated inside the outer contour of the motor vehicle formed by the wheel box 11, whereby they are adequately protected against external influences, as tests have shown.

Figure 2 shows the arrangement of the wheel and thetyre-pressure regulating unit on an axle 10. For greater clarity, the axle components not belonging to the invention, such as control arms, shock absorbers etc., are not designated It is evident that the wheel is mounted steerably on the axle 10 in a bearing 9. The pressure pipes 7, 8 are secured both inboard of the wheel in the vicinity of the bearing 9 and on the wheel outside to the rotary manifold 6. In this way the pipes 7,8 follow every movement, except rotation, of the wheel, whereby the clearance between the tyre 1 and the pressure pipes 7,8 is always assured. The protected arrangement of the rotary manifold 6 well within the interior of the wheel-rim disc is also evident.It is also evident that the pressure pipes 7, 8 do not extend beyond the outer contour of the motor vehicle, constituted by the wheel box 11.

An electropneumatic control and regulating device will normally be provided in the vehicle. Since this is not germane to the present invention; it is not discussed as described.

It is readily apparent from the drawings that inspection and maintenance of the most heavily loaded rotary manifold is particularly simple with this arrangement. Furthermore, it will be readily apparent that such design of a tyre-pressure regulating unit can also be subsequently fitted to motor vehicles, which was not possible or not always possible with the hitherto known designs. In this connection, it should be pointed out again that the design according to the invention has been shown to be extremely robust and reliable in operation in test runs over the most difficult terrain, with maximum axle displacement and when passing through undergrowth.

Claims (8)

1. Atyre-pressure regulating unit for a motor vehicle, comprising a rigid compressed-air line connected to the vehicle, a line arranged for rotation within the wheel, a rotary manifold which is arranged externally on the wheel rim and in alignment with the axle, and a connecting line from the rigid compressed-air line to the rotary manifold, wherein the rigid compressed-air line is carried with the wheel axle and a U-shaped bent pipe embracing the wheel is provided for the compressed-air supply from the axle to the rotary manifold.

2. Atyre-pressure regulating unit as claimed in Claim 1, wherein a wheel-control valve, mounted for rotation with the wheel, is provided and a further U-shaped bent pipe embracing the wheel is provided for supplying air to the valve.

3. Atyre-pressure regulating unit as claimed in Claim 2, wherein both pipes are disposed parallel with one another.

4. A tyre-pressure regulating unit as claimed in any one of Claims 1 to 3, wherein the or each U-shaped bent pipe is inclined rearwards by about 40 relative to the vertical.

5. A tyre-pressure regulating unit as claimed in any preceding claim, wherein the or each U-shaped bent pipe is so directed that it does not extend beyond the outermost contour of the vehicle.

6. Atyre-pressure regulating unit as claimed in any preceding claim, wherein, in addition to a wheel-control valve, a relief valve is also provided which is arranged protected within the vehicle body.

7. Atyre-pressure regulating unit as claimed in any preceding claim, wherein the rotary manifold is arranged protected within the wheel disc.

8. A tyre-pressure regulating unit substantially as herein described with reference to and as shown in the accompanying drawings.