GB2201755A

GB2201755A - Pressure equilibrating and/or safety device for fluid systems, particularly for motor vehicle tyres

Info

Publication number: GB2201755A
Application number: GB08804154A
Authority: GB
Inventors: Esterina Zorzi; Cero Daniele Dal
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-02-25
Filing date: 1988-02-23
Publication date: 1988-09-07
Also published as: GB8804154D0; IT8753066V0; DE3805575A1; FR2611248B1; FR2611248A1

Description

1 - - - 1 2201755 1 "Pressure equilibrating and/or safety device for fluid

systems, particularly for motor vehicle tyres".

The present invention relates to a device for use in a fluid system including chambers which can contain pressurised fluid.

The invention has been developed with particular attention to its possible use as a pressure equilibrating andlor safety device for tyres or sets of tyres of motor vehicles, particularly commercial vehicles.

However, the device can also be used with equal functionality and effectiveness in different fluid systems, for example, groups of liquid gas cylinders, etc.

The device according to the invention is characterised in that it comprises:.

- a body with at least two connectors which can each be connected to a respective one of the chambers and a duct which interconnects the at least two connectors, and - valve means interposed in the duct and sensitive to the pressure in the duct, the valve means having an operating threshold pressure which is fixed so that the valve means close the duct when the pressure in the duct falls to the operating threshold pressure.

Further characteristics and advantages of the invention will become clear form the description which follows, purely by way of non-limiting example, with reference to the appended drawings, in which:

Figure 1 shows a device according to the invention in median section, and Figures 2 to 4 show schematically some configurations 2 2 of use of the device according to the invention.

The device according to the invention, generally indicated 1, is constituted essentially by a body of metal or hard plastics material 2 obtained by the subjection of one or more pieces to mechanical working so as to form two or more connectors (3 and 4 in the embodiment of Figure 1) which enable the device 1 to be inserted in a fluid system including two or more chambers Cl, C 21 C 3 intended to contain pressurised f luid.

The nature and characteristics of these two chambers will be explained more fully below.

In Figure 1, the two branches, indicated 5, of a generally arcuate duct extending through the body 2 establish communication between the connectors 3 and 4 through a chamber 6, usually cylindrical, in which a piston 7 is movable axially.

More precisely, the two duct branches 5 open onto the base wall of the chamber 6 facing the connectors 3 and 4. A deformable diaphragm 71, usually of rubber, is fitted to this base wall and is intended to ensure the fluid-tight sealing of the portion of the chamber 6 into which the duct branches 5 open.

When the piston 7 is forced against the base wall of the chamber 6 into which the duct branches 5 open, the diaphragm 71 is forced against the ends of the ducts 5 sealingly to separate the connectors 3 and 4 and consequently the chambers connected thereto.

1 -5 1 3 When the piston 7 moves away from the base wall, however, the diaphragm 71 is free to extend into the chamber 6, enabling passage of the pressurised fluid between the connectors 3 and 4 and the chambers connected thereto.

Movement of the piston 7 within the chamber 6 is controlled by a helical spring 8 which acts on the piston 7, urging it into the position in which the ducts 5 are obturated with a force which is selectively adjustable by means of an adjustment screw 9.

In other words, the screw 9 enables the adjustment of the operating threshold pressure of the piston 7 which behaves to all intents like the obturator of a valve. When the fluid pressure in the duct branches 5 is greater than the operating threshold, the piston is urged away from the connectors 3 and 4 by the pressure, so that the connectors and the respective chambers are in communication with each other. When the pressure in the duct branches 5 drops below the operating threshold set by means of the screw 9 (typically due to a pressure drop in one of the chambers), however, the piston-obturator 7 closes the duct branches 5 to isolate the chambers from each other.

A warning sensor of some known type (not illustrated) may, to advantage, enable detection of the pressure drop causing displacement of the pistonobturator 7 towards the position in which the duct 5 is obturated, by the emission of a corresponding alarm signal intended, for example, to be transmitted to a central control.

In the embodiment to which Figure 1 refers, the chambers Cl. C 2 are constituted by two tyres of a motor 1 Z 4 vehicle. These could, for example, be two paired (twinned) tyres mounted on one half-axle of a commercial vehicle.

In this case, the operating threshold pressure of the piston-obturator 7 may be fixed at a pressure value (for example, atmosphere) corresponding to the minimum inflation pressure which is required to be maintained under all conditions by at least one of the tyres Cl j C 2 In this situation, as long as the pressure in the two tyres remains above the operating threshold, the two tyres are in communication with each other through the duct branches 5. The piston-obturator 7 is in fact kept in the position in which it is spaced from the base wall of the chamber 6 due to the pneumatic pressure acting against the diaphragm V. The pressure in the two tyres thus remains at the same level, which is advantageous for ensuring a balanced ride. If, for example, due to a puncture or a burst, the pressure in one of the tyres drops below the operating pressure, there is a drop in pressure in the corresponding branch of the duct 5 and in the chamber 6 such that the piston-obturator 7, urged by the spring 8, closes communication between the two connectors 3 and 4. The two tyres are thus separated from each other so that, even if one of the two is deflated due to a burst or puncture, the other safely retains the minimum pressure level fixed by means of the screw 9. The alarm sensor associated with the device simultaneously enables the pressure drop of one of the tyres to be signalled to the driver of the motor vehicle. The device according to the invention thus enables the use of a single warning sensor (possibly with an associated Z1 i k transmitter) for signalling an anomaly in one of the tyres, without the need to provide two sensors (and two associated transmitters) fgr this purpose.

In the embodiment to which Figure 3 relates, the chamber C 2 is again constituted by the tyre of a motor vehicle, whilst the chamber C 1 is constituted by the pipe which enables remote inflation of the tyre C 2 to be effected through a valve A. In a configuration of use frequently found in commercial motor vehicles, the pipe C 1 extends through the twinned tyre, illustrated by a broken line and indicated P. In this situation of use, the pipe C 1 may be cut due to relative movement of the twinned tyres.

In this case, the device 1, interposed between the pipe C 1 and the tyre C 2' enables inflation of the tyre to be carried out freely: in fact, the inflation pressure is such as to overcome the resistance of the pistonobturator 7, so that the air can flow freely into the tyre C 2 During normal use, the inflation pipe C 1 and the tyre C 2 are at the same pressure level, which is the inflation pressure of the tyre. If the pipe C 1 is accidentally cut or perforated, the pressure within the pipe C 1 drops. By virtue of a mechanism exactly the same as that described above with reference to Figure 2, this causes a pressure drop in the corresponding branch of the duct 5 in the chamber 6. The piston-obturator 7 operates to isolate the tyre C 2 from the outside, so that it retains a minimum level of inflation pressure selected by means of the screw 9.

The solution of Figure 4 constitutes a combination of the solutions illustrated in Figures 2 and 3.

6 In this case, the device 1 comprises three connectors 3, 4 and 34 extending radiallY through the body 2 in an arrangement essentially similar to that shown in Figure 1 with reference to only two connectors. The connectors 3 and 4 are connected to the two twinned tyres C 1 and C 21 while the connector 34 is connected to a common inflation pipe C 3 (acting as the third chamber of the system).

in this case also, the device 1 enables inflation of the two tyres C,. C 2 to be effected.through the valve A associated with the pipe C 31 furthermore ensuring that the same pressure level exists in the two tyres C,, C 2 in normal conditions of use; in these conditions, the two tyres C, j, C 2 actually communicate with each other and with the common inflation pipe C 3 In the presence of an anomaly which causes:

- a pressure drop in one or other of the tyres C,. C 21 or - a breakage and consequent pressure drop in the inflation pipe C 31 the device 1 intervenes (closure of the obturator 7) to isolate the connectors 3, 4 and 34 from each other and thus to isolate the tyre or tyres which are still intact from the damaged tyre or from the perforated pipe, ensuring that at least one of the tyres C 11 C2 retains an adequate inflation pressure in each case.

Naturally, the scope of the present invention extends to models which achieve equal utility by means of the same innovative concept and particularly to models in which:

- the device has a shape which differs from the generally T-shaped form illustrated in Figure 1, for A4 l!' f 7 example, a Y-shape or an angled shape, and - devices in which the piston-obturator 7 is controlled in a different manner, for example, by a solenoid valve operated by a pressure sensor which is sensitive to the pressure level in the branches of the duct 5, rather than having a spring of some sQrt.

j

Claims

8 CLAIMS

1. A device for use in a fluid system including chambers which can contain pressurised fluid, comprising:

- a body with at least two connectors which can each be connected to a respective one of the chambers and a duct which interconnects the at least two connectors, and - valve means interposed in the duct and sensitive to the pressure in the duct, the valve means having an operating threshold pressure which is fixed so that the valve means close the duct when the pressure in the duct drops to the operating threshold pressure.

2. A device according to Claim 1, in which the operating threshold pressure is selectively adjustable.

3. A device according to Claim 1 or Claim 2, in which the valve means comprise an obturator which is urged in the direction of closure of the duct by at least one resilient element.

4. A device according to Claim 3, in which the obturator carries an associated diaphragm for sealing the duct.

5. A pressure equilibrating and/or safety device for fluid systems, substantially as herein described with reference to, and as shown in, the accompanying drawings.

Published 1988 at The Patent OMce, 8tate House, 6(3171 High Holborn, London WClR 4TP. Further copies may be obtained from The Patent Office, Sales Branch, St Mary Cray, Orpington, Kent BRS 3RD. Printed by Multiplex technicraes ltd, St Mary Cray, Kent. Con- 1/87.