GB1599210A

GB1599210A - Control valves

Info

Publication number: GB1599210A
Application number: GB20607/78A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1977-09-17
Filing date: 1978-05-19
Publication date: 1981-09-30
Also published as: DE2742023A1; SE7809685L; FR2403251A1; FR2403251B3; BR7806034A; SE437133B

Description

(54) IMPROVEMENTS IN OR RELATIN G TO CONTROL VALVES (71) We, ROBERT Botch GmbH, a German 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 control valves, particularly for motor vehicle brake systems.

In one known form of control valve comprising a thrust-piece provided with a cupshaped recess which receives a push rod whereby the thrust piece can be displaced to act through a spring on a reaction piston which actuates a double seat valve, the recess allows the push rod or tappet to execute a certain swivelling movement in order to compensate for the effect of eccentric forces.

However, in the known valve the recess is arranged outside the spring, so that the valve has a great length of construction, which is a disadvantage in narrow space conditions, as they occur in particular in motor vehicles. Moreover the known control valve is constituted of relatively many parts in the region of the tappet.

According to the present invention, there is provided a control valve, for a vehicle brake system, comprising a thrust-piece provided with a cup-shaped recess or the like which receives a push rod or tappet whereby the thrust-piece can be displaced to act through a spring on a reaction piston which actuates a valve element of a valve which monitors flow from a supply inlet to a pressure chamber and from the pressure chamber to exhaust, the reaction piston being exposed to the pressure in the pressure chamber, in which the thrust-piece projects at least into the spring and is provided with a shoulder and a pin extending beyond the shoulder and passing centrally through a base of the reaction piston, the pin having on its free end at the side of the piston base remote from the spring a clamping part which abuts the base of the reaction piston and thereby holds the spring under initial prestress.

A control valve embodying the present invention can have the advantage that it can be af very short construction. It can therefore be very readily accommodated also in case of narrow space conditions. Moreover, there are fewer components in the region of the reaction piston, so that it is cheaper than the known type. Finally the invention can be used to equal advantage for a control valve with a rubber spring as with a steel spring.

The invention will be further described by way of example with reference to the accompanying drawings in which : - Fig. 1 is an axial section through a control valve in the form of a two-circuit brake valve with a rubber spring, according to a first embodiment of the invention Fig. 2 is a partial axial section through a control valve similar to that of Fig. 1 but vJitll a steel spring, Fig. 3 is a partial axial section through a control valve, according to a second em bodiment of the invention and Fig. 4 is part of the valve of Fig. 3.

Referring first to Fig. 1, a control valve 1 is constructed as a two-circuit control valve and is intended for a motor vehicle brake system. The control valve 1 comprises a housing with two supply line connections 3 and 4, two connections 5 and 6 for brake lines 7 and 8 and an exhaust or pressure relief connection 9.

Inside the housing 2, two double-seat valves 10 and 11 are arranged one above the other and each has an inlet valve and an outlet valve, which monitor the connection of the brake lines 7 and 8 either with the supply line connections 5 and 6 or with the exhaust connection 9. An outlet seat 12,13 respectively of the double-seat valves 10,11 respectively is located on a balancing piston 14 which balances out the controlled brake pressures against one another. Each doubleseat valve 10,11 respectively is provided with a valve closure member 15,16 respectively, which is loaded by a valve spring 151,161 respectivelv. and which is hollow to permit pressure relief and connection to outside atmosphere.

In the upper part of the housing 2, a two part reaction piston 17 carries an inlet valve seat 18 of the first double-seat valve 10 and can be displaced by a push rod 19 through a thrust-piece 20 with a cup-shaped recess 21 for the push rod 19 and through a spring 22. An inlet valve seat 23 of the second double-seat valve 11 is fixed relatively to the housing.

The thrust piece 20 projects into the spring 22. It has a shoulder 24 which in the illustrated position is spaced a distance "A" from a base 25 of the reaction piston 17.

A pin 26 extends from the shoulder 24 of the thrust-piece 20, passes centrally through the piston base 25 and has at its end a threaded portion 27. A nut 28 is screwed onto the threaded portion 27.

By means of the nut 28 an initial or prestress is imparted to the spring 22 which acts between the piston 17 and a washer 30 engaging a flange 29 of the thrust piece 20.

An outer edge of the washer 30 serves for guiding the thrust-piece 20 inside an annular housing insert 31, against which the thrustpiece flange 29 rests in the initial or resting position of the control valve.

The control valve described above operates as follows: The initial prestress of the spring 22 is adjusted by means of the nut 28. The initial prestress is chosen so that it is equal to or greater than the forces opposing the actuation of the control valve comprising the valve spring 151, and the supply pressure at connection 3 as well as friction. Thus the initial prestress is adiusted so that these forces are first overcome and the inlet valve pushed open, whilst at the same time or only subsequently is the initial stress of the spring overcome and the spring then yields. For a two-circuit brake valve with two single valves arranged in tandem, as illustrated in the drawing, the initial prestress of the spring can be adiusted to a value greater than the sum of the actuating forces of both single valves.The result of this arrangement is that the spring will only yield when both inlet valves are open.

After the opening of the inlet valves of the two double-seat valves 10 and 11, the balancing piston 14 ensures compensation between the two brake circuits.

In the embodiment of Fig. 2, a control valve 32 is illustrated which is equipped with a steel sprint 33 instead of the rubber spring 30 in the embodiment of Fig. 1. Components corresponding to those in the embodiment of Fig. 1 are given the same reference numerals as in Fig. 1. The steel spring 33 is damped between a plastics flange ring 34 and a spring abutment plate 35. The flange ring 34 rests with interposition of a washer 291 firmly against the flange 29 of the thrustpiece 20, and the spring abutment plate 35 forms a fixed piston base on a piston 36. In this embodiment the nut 28 that can be screwed onto the pin 26 of the thrust piece 20 engages the spring abutment plate 35.

For the rest, the method of operation of this control valve 32 and the adjustment of the initial prestress of the spring 33 are the same as in the embodiment of Fig. 1.

Fig. 3 shows partly in section a control valve 38 according to a third embodiment of the invention in which a thrust-piece 39 has a pin 40 which instead of a thread is provided with a fixed head 41. The head 41 has a diameter greater than the diameter of the pin. A base 42 of the pro-part reaction piston 43 has a radially extending opening 44 in the shape of a keyhole through which the pin 40 can pass. The opening 44 is provided eccentrically with a portion 45 of enlarged width through which pin head 41 can pass. With the help of this portion 45 it is possible to pass the pin head 41 eccentrically through the base. Subsequently the pin 40 is axially aligned with the reaction piston 43, whereupon the head of the pin is located against the base 42 of the reaction piston around the selectively narrower part of the elongated opening 44.

The initial prestress of the spring 22 so adjusted can be modified by inserting spacers. One such spacer 46 is located between the spring 22 and the washer against the flange of the thrust piece 20. The method of operation of this control valve 38 is the same as that of the control valve of Fig. 1.

It will be apparent that all the embodiments of the control valve can be constructed in a very short and compact manner in the region of the push rod 19. Each can therefore be accommodated without difficulties in narrow space conditions, such as those encountered in particular in motor vehicles.

Moreover, each of the control valves has fewer components compared with other known types.

WHAT WE CLAIM IS:- 1. A control valve for a vehicle brake system, comprising a thrust-piece provided with a cup-shaped recess or the like which receives a push rod or tappet whereby the thrust-piece can be displaced to act through a spring on a reaction piston which actuates a valve element of a valve which monitors flow from a supply inlet to a pressure chamber and from the pressure chamber to exhaust, the reaction piston being exposed to the pressure in the pressure chamber, in which the thrust-piece projects at least into the spring and is provided with a shoulder and a' pin extending beyond the shoulder and passing centrally through a base of the reaction piston, the pin having on its free end at the side of the piston base remote from the spring a clamping part which abuts

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. part reaction piston 17 carries an inlet valve seat 18 of the first double-seat valve 10 and can be displaced by a push rod 19 through a thrust-piece 20 with a cup-shaped recess 21 for the push rod 19 and through a spring 22. An inlet valve seat 23 of the second double-seat valve 11 is fixed relatively to the housing. The thrust piece 20 projects into the spring 22. It has a shoulder 24 which in the illustrated position is spaced a distance "A" from a base 25 of the reaction piston 17. A pin 26 extends from the shoulder 24 of the thrust-piece 20, passes centrally through the piston base 25 and has at its end a threaded portion 27. A nut 28 is screwed onto the threaded portion 27. By means of the nut 28 an initial or prestress is imparted to the spring 22 which acts between the piston 17 and a washer 30 engaging a flange 29 of the thrust piece 20. An outer edge of the washer 30 serves for guiding the thrust-piece 20 inside an annular housing insert 31, against which the thrustpiece flange 29 rests in the initial or resting position of the control valve. The control valve described above operates as follows: The initial prestress of the spring 22 is adjusted by means of the nut 28. The initial prestress is chosen so that it is equal to or greater than the forces opposing the actuation of the control valve comprising the valve spring 151, and the supply pressure at connection 3 as well as friction. Thus the initial prestress is adiusted so that these forces are first overcome and the inlet valve pushed open, whilst at the same time or only subsequently is the initial stress of the spring overcome and the spring then yields. For a two-circuit brake valve with two single valves arranged in tandem, as illustrated in the drawing, the initial prestress of the spring can be adiusted to a value greater than the sum of the actuating forces of both single valves.The result of this arrangement is that the spring will only yield when both inlet valves are open. After the opening of the inlet valves of the two double-seat valves 10 and 11, the balancing piston 14 ensures compensation between the two brake circuits. In the embodiment of Fig. 2, a control valve 32 is illustrated which is equipped with a steel sprint 33 instead of the rubber spring 30 in the embodiment of Fig. 1. Components corresponding to those in the embodiment of Fig. 1 are given the same reference numerals as in Fig. 1. The steel spring 33 is damped between a plastics flange ring 34 and a spring abutment plate 35. The flange ring 34 rests with interposition of a washer 291 firmly against the flange 29 of the thrustpiece 20, and the spring abutment plate 35 forms a fixed piston base on a piston 36. In this embodiment the nut 28 that can be screwed onto the pin 26 of the thrust piece 20 engages the spring abutment plate 35. For the rest, the method of operation of this control valve 32 and the adjustment of the initial prestress of the spring 33 are the same as in the embodiment of Fig. 1. Fig. 3 shows partly in section a control valve 38 according to a third embodiment of the invention in which a thrust-piece 39 has a pin 40 which instead of a thread is provided with a fixed head 41. The head 41 has a diameter greater than the diameter of the pin. A base 42 of the pro-part reaction piston 43 has a radially extending opening 44 in the shape of a keyhole through which the pin 40 can pass. The opening 44 is provided eccentrically with a portion 45 of enlarged width through which pin head 41 can pass. With the help of this portion 45 it is possible to pass the pin head 41 eccentrically through the base. Subsequently the pin 40 is axially aligned with the reaction piston 43, whereupon the head of the pin is located against the base 42 of the reaction piston around the selectively narrower part of the elongated opening 44. The initial prestress of the spring 22 so adjusted can be modified by inserting spacers. One such spacer 46 is located between the spring 22 and the washer against the flange of the thrust piece 20. The method of operation of this control valve 38 is the same as that of the control valve of Fig. 1. It will be apparent that all the embodiments of the control valve can be constructed in a very short and compact manner in the region of the push rod 19. Each can therefore be accommodated without difficulties in narrow space conditions, such as those encountered in particular in motor vehicles. Moreover, each of the control valves has fewer components compared with other known types. WHAT WE CLAIM IS:-

1. A control valve for a vehicle brake system, comprising a thrust-piece provided with a cup-shaped recess or the like which receives a push rod or tappet whereby the thrust-piece can be displaced to act through a spring on a reaction piston which actuates a valve element of a valve which monitors flow from a supply inlet to a pressure chamber and from the pressure chamber to exhaust, the reaction piston being exposed to the pressure in the pressure chamber, in which the thrust-piece projects at least into the spring and is provided with a shoulder and a' pin extending beyond the shoulder and passing centrally through a base of the reaction piston, the pin having on its free end at the side of the piston base remote from the spring a clamping part which abuts

the base of the reaction piston and thereby holds the spring under initial prestress.

2. A control valve as claimed in claim 1 in which a distance between the shoulder and the piston base determines the extent to which the spring can be compressed after overcoming its initial prestress.

3. A control valve as claimed in claim 1 or 2, in which the clamping part is a nut which can be screwed onto a threaded end portion of the pin for modifying the initial prestress of the spring.

4. A control valve as claimed in claim 1, 2 or 3, in which the piston base is formed by a spring abutment plate which rests firmly against the reaction piston.

5. A control valve as claimed in claim 1 or 2, in which the clamping part is a head of the pin with a diameter greater than the diameter of the pin, and in which the piston base has a radially extending opening in the form of a keyhole through which the pin can pass, in that the opening has an eccentric portion of larger width corresponding to that of the head of the pin and through which the head of the pin can pass eccentrically.

6. A control valve as claimed in claim 5, in which the initial prestress of the spring is determined by a least one spacer disposed between the spring and the reaction piston or between the spring and the thrust-piece.

7. A control valve as claimed in any of claims 1 to 6, which is in the form of a twocircuit control valve with two single valves arranged in tandem.

8. A control valve as claimed in claim 7, in which the initial prestress of the spring corresponds at least to the sum of the actuating forces of both single valves.

9. A control valve as claimed in any preceding claim, in which the valve element belongs to a double-seat valve whose elements are an inlet valve seat, an outlet valve seat and a common valve closure member co-operating with said seats.

10. A control valve as claimed in claim 9, in which the inlet valve seat is on the reaction piston.

11. A control valve for a vehicle brake system, constructed and adapted to operate substantially as hereinbefore particularly described with reference to and as illustrated in Fig. 1 or Fig. 2 or Figs. 3 and 4 of the accompanying drawin.