GB1591970A

GB1591970A - Circuit protective valves

Info

Publication number: GB1591970A
Application number: GB21464/78A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1977-08-29
Filing date: 1978-05-23
Publication date: 1981-07-01
Also published as: DE2738842A1; IT7827041A0; IT1098700B; FR2402139A1

Description

(54) IMPROVEMENTS IN OR RELATING TO CIRCUIT PROTECTIVE VALVES (71) We, ROBERT BOSCH GmbH, a Germany company of Postfach 50, 7 Stuttgart 1, Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to circuit protective valves.

One known form of circuit protective valve has a valve closure member which is disposed at the base of a cup-shaped member and which co-operates with a valve seat which is fixed in the valve housing and towards which it is urged by a spring disposed in the cup-shaped member.

This form of valve is suitable for installation in a housing. In the case of a multiple valve arrangement, such as is necessary, for example, when used as a multi-circuit protective valve assembly for a vehicle compressed air braking system, the total effect is a complicated unit which takes up a great deal of space.

According to the present invention there is provided a circuit protective valve, comprising a housing having a compressed-air outlet passage, an annular body inserted and fixed in an extension of the inlet passage internally of the housing, a sealing ring sealing the annular body to the inlet air passage, the annular body having thereon an annular valve seat downstream of the inlet passage, a cup-shaped member displaceably guided in the housing and having on its base a valve closure co-operating with the valve seat, and a spring disposed in the cup-shaped member and acting thereon to urge the closure against the valve seat, the arrangement being such that a desired minimum pressure in the inlet passage, lifts the valve closure part from the valve seat against the spring force and is maintained by a throttling action in the event of a pressure loss from the outlet passage.

A protective valve embodying the present invention can have the advantage that its single pattern which basically comprises the cupshaped member and the annular body, is very versatile. While being inexpensive to produce, it can be used both as a single circuit-protective valve and as a built-in element in a multi-circuit protective valve assembly, and it may be constructed either with or without a nonreturn valve. The annular bodies for a fourcircuit protective valve assembly and for a safety valve differ, however, in sealing diameter and throttle action.

By using the annular body, both the valve seal and a throttle gap are provided not on the housing - which would necessitate expensive processing of the housing - but on the annular body so that manufacture is made simpler. The annular body can be an inexpensive die cast metal part or a moulded part which may be finished separately before insertion into the housing. After its manufacture in the first instance, the annular body is inserted in the housing and is fixed there by a caulking.

This makes it possible, if required, to fixing the valve closure body of a non-return valve on the underside of the annular body, the seat of the non-return valve being formed on a shoulder of an air-inlet channel.

The invention will be further described by way of example, with reference to the accompanying drawings, in which: Figure 1 is a longitudinal section through one embodiment of circuit protective valve according to the present invention; and Figure 2 is a sectional view of a multicircuit protective valve according to the present invention.

Referring initially to Figure 1, a circuit protective valve comprises a housing 1 which has on one side an inlet 2 having a threaded connection 3 and on the other side, coaxial with the inlet 2, an outlet 4 having a threaded connection 5. Adjoining the inlet 2 at right angles is an air-inlet channel 6 coaxial with a multistepped housing bore 7 whose axis is perpendicular to the axis of the inlet 2 and outlet 4.

A shoulder 8 in the air-inlet channel 6 serves as a bearing surface for an annular body 9 which is a die cast metal part or a moulded part and is finished before insertion into the housing 1. On its outer surface it has an annular groove 10 for fixing the annular body 9 in the housing 1. This is achieved by caulking 13 which is applied at several points of a shoulder 14 in the housing and distributed uniformly around its periphery.

The annular body 9 is inserted into an exten sion 12 of the air-inlet channel 6 together with a sealing ring 11 and is in this way sealed.

The annular body 9 is provided with an annular valve seat 29 inside the caulking 13.

The housing bore 7 accomodates a tubular member 15 and a cap 16 each having a flange 17,18 respectively. The two flanges 17 and 18 are fixed between a bore shoulder 19 and a spring ring 20 in the bore 7.

An externally actuable screw 21 having a nut 22 is inserted in the cap 16, the nut 22 being fitted into the cap 16 in such a manner as to be non-rotatable. A spring abutment 23 engaged on the inner end of the screw abuts one end of a spring 24 which extends through the tubular member 15 and of which the other end acts on a cup-shaped member 25.

This cup-shaped member 25 is a metalreinforced plastics material part provided at its cup edge with an annular sealing lip 26 by means of which it is placed slidingly and sealingly on an outer surface of the tubular member 15. A base surface of the cup-shaped member 25 is a valve closure member of the safety valve and cooperates with the valve seat 29 carried by the annular body 9, a throttle gap being formed between the base surface and the annular body. As illustrated, a non-return valve 27 may if desired be provided inside the annular body 9. The non-return valve 27 has a valve closure member 28 fixed on the annular body 9.For this purpose, the valve closure member 28 is frusto-conical in shape and of a yielding material and has on its smaller diameter an extension 30 by means of which it is fixed centrally in the annular body 9 leaving coaxial channels 31 for the flow through of air. On its larger diameter the valve closure member 28 has a resilient annular edge 32 which normally rests in a lip-like manner against the shoulder 8.

The valve described above operators as follows: With no pressure in the inlet 2, the movable parts of the valve assume the positions illustrated in Figure 1. When the pressure in the inlet 2 is increased, the annular edge 32 is raised from the shoulder 8 and the non-return valve 27 opens. The pressure under the cupshaped member 25 then rises in turn. Depending upon the initial stress of the spring 24 adjusted by the screw 21, at a predetermined level of the input pressure the cup-shaped member 25 is lifted from its valve seat 29 and the circuit protective valve is opened. At the start of this lifting of the cup-shaped member 25, the air flowing through is throttled by the narrow annular passage inside the annular valve seat 29 which only permits the pressure to build-up in a delayed manner under the surface inside the valve seat 29.In the course of the lifting process, the throttle action is reduced down to zero once the member 25 is fully lifted.

When the protective valve is fully opened, it is held open by the pressure in the outlet passage 4 and air can flow impeded through it; however, the non-return valve-27 always remains fully effective. If there should be a loss of pressure in the outlet passage 4, the spring 24 urges the cup-shaped member 25 towards the valve seat 29 and so the above mentioned throttle action is re-introduced, whereby the air passage in the inlet passage 2 is prevented from falling below the valve at which the cup-shaped member is lifted. If there should be a loss of pressure in the inlet 2, the nonreturn valve 27 closes to hold the pressure in the outlet passage 4.

Figure 2 illustrates how the protective valve embodying the present invention can be used in multiple groupings as a multi-circuit protective valve assembly for compressed-air braking systems, preferably of motor vehicles. It may be seen that its single pattern, which basically comprises the valve closure members, i.e.

the cup-shaped member 25 and the annular body 9, is very versatile, for example as illustrated in a multi-circuit protective valve assembly. Such a valve assembly 35 is inserted between a compressor and two compressed air supply reservoirs and has a number of protective valves corresponding to the number of circuits to be protected; the valves from a predetermined pressure level, open an air passage through the valves and are each provided with a restrictor or throttle and a non-return valve.

Should there be a pressure loss in one of the outlet passages, the respective protective valve throttles the air flowing to the defective circuit to keep the inlet pressure at a valve sufficient to maintain the supply to the remaining circuits. The purpose of the non-return valves is to maintain full pressure in the individual circuits in the event of a breakdown in pressure supply.

One frequently used multi-circuit protective valve assembly serves to protect four circuits.

For such an assembly four protective valves are required and the non-return valves function to protect individual brake circuits against pressure drop in the event of failure or leakage in any other circuit.

If required, a valve assembly can be made in a multiple grouping in that safety or protective valves are assembled next to and/or behind one another. It is, of course, also possible by omitting a valve closure member 28 to dispense with a non-return valve 27 in a safety valve.

WHAT WE CLAIM IS:- 1. A circuit protective valve comprising a housing having a compressed-air inlet passage and a compressed-air outlet passage, an annular body inserted and fixed in an extension of the inlet passage internally of the housing, a sealing ring sealing the annular body to the inlet passage, the annular body having thereon an annular valve seat downstream of the inlet passage, a cup-shaped member displaceably guided in the housing and having on its base a valve closure part co-operating with the

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. sion 12 of the air-inlet channel 6 together with a sealing ring 11 and is in this way sealed. The annular body 9 is provided with an annular valve seat 29 inside the caulking 13. The housing bore 7 accomodates a tubular member 15 and a cap 16 each having a flange 17,18 respectively. The two flanges 17 and 18 are fixed between a bore shoulder 19 and a spring ring 20 in the bore 7. An externally actuable screw 21 having a nut 22 is inserted in the cap 16, the nut 22 being fitted into the cap 16 in such a manner as to be non-rotatable. A spring abutment 23 engaged on the inner end of the screw abuts one end of a spring 24 which extends through the tubular member 15 and of which the other end acts on a cup-shaped member 25. This cup-shaped member 25 is a metalreinforced plastics material part provided at its cup edge with an annular sealing lip 26 by means of which it is placed slidingly and sealingly on an outer surface of the tubular member 15. A base surface of the cup-shaped member 25 is a valve closure member of the safety valve and cooperates with the valve seat 29 carried by the annular body 9, a throttle gap being formed between the base surface and the annular body. As illustrated, a non-return valve 27 may if desired be provided inside the annular body 9. The non-return valve 27 has a valve closure member 28 fixed on the annular body 9.For this purpose, the valve closure member 28 is frusto-conical in shape and of a yielding material and has on its smaller diameter an extension 30 by means of which it is fixed centrally in the annular body 9 leaving coaxial channels 31 for the flow through of air. On its larger diameter the valve closure member 28 has a resilient annular edge 32 which normally rests in a lip-like manner against the shoulder 8. The valve described above operators as follows: With no pressure in the inlet 2, the movable parts of the valve assume the positions illustrated in Figure 1. When the pressure in the inlet 2 is increased, the annular edge 32 is raised from the shoulder 8 and the non-return valve 27 opens. The pressure under the cupshaped member 25 then rises in turn. Depending upon the initial stress of the spring 24 adjusted by the screw 21, at a predetermined level of the input pressure the cup-shaped member 25 is lifted from its valve seat 29 and the circuit protective valve is opened. At the start of this lifting of the cup-shaped member 25, the air flowing through is throttled by the narrow annular passage inside the annular valve seat 29 which only permits the pressure to build-up in a delayed manner under the surface inside the valve seat 29.In the course of the lifting process, the throttle action is reduced down to zero once the member 25 is fully lifted. When the protective valve is fully opened, it is held open by the pressure in the outlet passage 4 and air can flow impeded through it; however, the non-return valve-27 always remains fully effective. If there should be a loss of pressure in the outlet passage 4, the spring 24 urges the cup-shaped member 25 towards the valve seat 29 and so the above mentioned throttle action is re-introduced, whereby the air passage in the inlet passage 2 is prevented from falling below the valve at which the cup-shaped member is lifted. If there should be a loss of pressure in the inlet 2, the nonreturn valve 27 closes to hold the pressure in the outlet passage 4. Figure 2 illustrates how the protective valve embodying the present invention can be used in multiple groupings as a multi-circuit protective valve assembly for compressed-air braking systems, preferably of motor vehicles. It may be seen that its single pattern, which basically comprises the valve closure members, i.e. the cup-shaped member 25 and the annular body 9, is very versatile, for example as illustrated in a multi-circuit protective valve assembly. Such a valve assembly 35 is inserted between a compressor and two compressed air supply reservoirs and has a number of protective valves corresponding to the number of circuits to be protected; the valves from a predetermined pressure level, open an air passage through the valves and are each provided with a restrictor or throttle and a non-return valve. Should there be a pressure loss in one of the outlet passages, the respective protective valve throttles the air flowing to the defective circuit to keep the inlet pressure at a valve sufficient to maintain the supply to the remaining circuits. The purpose of the non-return valves is to maintain full pressure in the individual circuits in the event of a breakdown in pressure supply. One frequently used multi-circuit protective valve assembly serves to protect four circuits. For such an assembly four protective valves are required and the non-return valves function to protect individual brake circuits against pressure drop in the event of failure or leakage in any other circuit. If required, a valve assembly can be made in a multiple grouping in that safety or protective valves are assembled next to and/or behind one another. It is, of course, also possible by omitting a valve closure member 28 to dispense with a non-return valve 27 in a safety valve. WHAT WE CLAIM IS:-

1. A circuit protective valve comprising a housing having a compressed-air inlet passage and a compressed-air outlet passage, an annular body inserted and fixed in an extension of the inlet passage internally of the housing, a sealing ring sealing the annular body to the inlet passage, the annular body having thereon an annular valve seat downstream of the inlet passage, a cup-shaped member displaceably guided in the housing and having on its base a valve closure part co-operating with the

valve seat, and a spring disposed in the cupshaped member and acting thereon to urge the closure part against the valve seat, the arrangement being such that a desired minimum pressure in the inlet passage lifts the valve closure part from the valve seat against the spring force and is maintained by a throttling action in the vent of a pressure loss from the outlet passage.

2. A valve as claimed in Claim 1, in which the annular body is held securely in the valve housing by caulking.

3. A valve as claimed in Claim 1 or 2, in which the annular body is a die cast metal part or a moulded part.

4. A valve as claimed im Claim 1, 2 or 3, in which a valve closure member of a non-return valve is fixed on the annular body, and a valve seat of the non-return valve is provided on a shoulder of the air-inlet passage.

5. A valve as claimed in Claim 4, in which the valve closure member of the non-return valve is a frusto-conical in shape and of a yielding material and has a resilient annular edge on its larger diameter.

6. A valve as claimed in Claim 5, in which the frusto-conically shaped valve closure member has on its smaller diameter an extension by means of which it is fixed centrally in the annular body leaving coxial air channels for air flow through.

7. A valve as claimed in any preceding claim in which the cup-shaped member is sealingly guided in the housing so that it is held in the housing so that it is held in the fully open position by the pressure of the air in the outlet passage so long as the outlet pressure remains above a predetermined valve.

8. A valve as claimed in any claims 1 to 7, assembled with other similar valves in multiple groupings next to and/or behind one another to form a valve assembly for use as a multicircuit protective valve assembly for compressed-air braking systems.

9. A valve assembly as claimed in Claim 8, in which all of the valves have a common housing.

10. A circuit protective valve, constructed and arranged and adapted to operate substantially as hereinbefore particularly described with reference to and as illustrated in Figure 1 of the accompanying drawings.

11. A multi-circuit protective valve assembly constructed and arranged substantially as hereinbefore particularly described with reference to and as illustrated in Figure 2 of the accompanying drawings.