GB1599867A

GB1599867A - Pressure-control valve assemblies

Info

Publication number: GB1599867A
Application number: GB2272078A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1978-03-09
Filing date: 1978-05-25
Publication date: 1981-10-07
Also published as: JPS643700B2; DE2810219A1; JPS54126337A; DE2810219C2

Description

(54) IMPROVEMENTS IN OR RELATING TO PRESSURE-CONTROL VALVE ASSEMBLIES (71) We, ROBERT BOSCH 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 pressurecontrol valve assembles for wheel brakes of motor vehicles.

In one known pressure-control valve unit for an anti-skid system for wheel brakes of motor vehicles a relay valve only monitors an atmospheric air connection.

Furthermore, it is known to construct anti-skid pressure-control values as fully effective relay valves. In addition to a saving on the special relay valve required in many cases, or even a rapid-release valve, the main advantages are:during normal braking (without anti-skid regulation) rapid pressurizing and venting in the case of long brake lines rapid release action when releasing the brake moving of the actuating elements each time the brake is applied load-dependent control devices having small flow-through cross sections when connected in the control circuit.

during regulation braking (anti-skid regulation) pressure gradient rendered largely independent of the volume of the brake cylinder as a result of standardisation. The quality of regulation is not affected by brake cylinders of differing sizes or the effective cylinder volume being rendered larger by wear on the brake linings possibility of connecting and regulating a plurality of brake cylinders simultaneously, such as in the case of regulation per axle.

However, the regulating function is impaired by the relatively large volume of these values. The long actuating times caused thereby result in undermodulation values of the pressure which do not permit adequate power for the regulation of individual wheels.

Furthermore, relay pressure-control valves are too expensive for individual wheel regulation since, with this type of regulation, a relay pressure-control valve is required for each wheel.

Therefore, relay pressure-control valves are used predominantly as axle regulating valves, that is, for a system of regulation in which is plurality of brake cylinders are simultaneously regulated to a common level of brake pressure.

On the other hand, rapid-acting control valves of simple construction (without relay function and without proportional characteristics) and having a small volume are used for the regulation of individual wheels and, by reason of the function characteristic, do not have the advantages, also desirable for individual wheel regulation, of the relay pressure-control valves.

According to the present invention there is provided a pressure-control valve assembly for an anti-skid system for wheel brakes of motor vehicles comprising a valve unit in which a three port, two position valve responsive to a control pressure is provided for a single- or multi-channel control, and a two port, two position valve is provided for each channel, in combination with a supplementary three port, two position valve connected to a brake valve control line and a compressed air supply line.

A pressure-control valve assembly embodying the present invention can have the advantage that, by combining individual actuating elements of relay valves and control valves, the advantages of these two groups of valves can be combined without having to accept their disadvantages.

Furthermore, it is advantageous that the pressure-control valve assembly opens up new ranges of application over and above the normal anti-skid function and which can be. obtained by relatively simple supplementary controls.

The supplementary three port, two position valve can be arranged either on or in the pressure-control valve unit itself, or anywhere in the vehicle. The three port, two position valve can be in the form of a solenoid valve. Alternatively, however, the controlled introduction of pressure into individual brake cylinders can be effected by means of a normal mechanically operated three port, two position valve which, for example, can be engaged by the driver by means of a handle whenever the regulation of drive slip is required.

'When a locking button having a withdrawable key is provided instead of the handle, an anti-theft safeguard can be additionally provided which prevents or at least hinders theft of the vehicle in a simple manner through a single operation causing full pressure to be applied continuously to the connected brake cylinders.

Furthermore, with the exclusive -use of solenoid valves, a construction embodying the present invention has the advantage that all the valve elements, including the solenoid valves can be tested under pressure. Although pressure is introduced into the relay valve by the simultaneous setting of all the solenoid valves, a further build-up of brake pressure in brake cylinders is prevented by shutting off the two-position valves, so that a test cycle can be performed even when the vehicle is travelling.

It is also advantageous that, when full pressure is applied continuously to connected brake cylinders as an anti-theft safeguard, the control chambers are controlled by brake valve pressure. Thus, it is ensured that the brakes can be released by the driver at any time irrespective of the position of the valve or the position of the solenoid, an advantage which, in the known constructions, has to be provided by additional non-return valves.

It is also advantageous that, in each case, only small control chambers have to be pressurized or vented by way of the solenoid valves or, alternatively, by way of the mechanically operable three port, two position valve. Thus, these valves can be constructed with small flow-through cross sections which are advantageous with respect to costs.

This advantage also applies when an automatic load-dependent brake force control device is connected with control in the control circuit.

As a result of this, and also by virtue of the saving on the relay valve required in many cases, considerable advantages with respect to costs can be obtained.

By way of example, compared with conventional anti-skid pressure control valves, the following devices can be dispensed with on the rear axle of a tractor vehicle, or smaller devices can be used: 1 Relay valve 1 Anti-skid pressure control valve 1 Rapid-release valve Furthermore, a mechanical differential lock and expensive anti-theft devices can be omitted. Finally, any load-dependent brake force regulator required can be of smaller dimensions.

The invention will be further described by way of example with reference to Figs. 2 to 6 of the accompanying drawings in which: Fig. I is a section through a pressurecontrol valve unit used in the embodiments of Figs. 2 to 5, Fig. 2 shows diagrammatically an assembly including a valve unit of Fig. 1 and an integrated supplementary three port, two position solenoid valve, Fig. 3 shows diagrammatically an assembly including a valve unit of Fig. 1 and an external supplementary three port, two position solenoid valve, Fig. 4 shows diagrammatically an assembly including a valve unit of Fig. 1 and a supplementary valve for manual actuation, Fig. 5 shows diagrammatically an assembly including a valve unit of Fig. 1 and a lockable supplementary three port, two position solenoid valve, and Fig. 6 shows diagrammatically an assembly having conventional control valves and a supplementary valve.

A pressure-control valve unit 4 which forms part of each of the embodiments of Figs. 2 to 5 will first be described in detail with reference to Fig. 1. Such pressurecontrol valve unit is described in greater detail in the complete specification of our copending Patent Application No. 22719/78 (Serial No. 1,599,866). A pressure-control-valve unit 4 is connected through a foot-brake valve 2 to a reservoir 1, and is also connected to the reservoir 1 through a compressed air supply line 3. A control line 5 is connected between the brake valve 2 and the pressure-control valve unit 4.

The compressed air supply line 3 is connected, in the pressure-control valve unit 4, to a supply pressure chamber 6 which has a valve seat 7 for a valve closure member 8 of a relay valve 9. A pressurerelieved plunger 10 of the valve closure member 8 passes through the valve seat 7 and its other end carries a diaphragm plate 11 intended for co-operation with a control diaphragm 12.

The plunger 10 and the diaphragm plate 11 are located in a pressure-change chamber 13 which is defined by a valve seat 14 and which is subjected to supply pressure when the diaphragm 12 is located on the seat 14, and is connected to atmospheric air by way of an annular passage 15 when the diaphragm 12 is moved away from the seat 14 (see also Figs. 2 and 3). The seat 14 and the diaphragm 12 thus form an outlet valve 12, 14. A control chamber 12' is disposed below the diaphragm 12.

In the two-channel construction shown in Figure 1, the pressure-change chamber 13 has, at the ends thereof, two further valve seats 16 and 17 of two two port, two position valves 18 and 19 whose diaphragm valve closure members 20 and 21 are arranged in chambers 22 and 23 respectively to which are connected brake cylinder lines 26 and 27 leading to the brake cylinders 24 and 25 respectively. Control chambers 33 and 34 are located at the other sides of the diaphragm valve closure members 20 and 21 respectively.

Three solenoid valves 29, 30 and 31 are arranged in a bottom portion 28 of the housing, the central solenoid valve 30 being in the form of a three port, two position valve and the other two solenoid valves 29 and 31 being in the form of three port, two position valves. The solenoid valves 29, 30, 31 are pilot control valves for the control chambers 33, 12' and 34 respectively. The bottom of the bottom portion 28 of the housing has an atmospheric air connection 32 controlled by a non-return valve, and the top of the bottom portion 28 of the housing is covered by an upper portion 50 which accommodates the relay valve 9 and the outlet valve 12, 14.

The unit described above operates as follows: When the solenoid valve 30 is open (deenergized) pressure from the reservoir 1 is admitted to the control chamber 12' by way of the control line 5. The control diaphragm 12 moves upwardly, abuts against the valve seat 14, and thus shuts off the reaction pressure/relief connection (shown more clearly in Figure 2).

The pressure-relieved valve plunger 10 is subsequently raised by the diaphragm plate I 1 and the valve closure member 8 is lifted from the valve seat 7. Compressed air flows out of the chamber 6 to the brake cylinders 24 and 25 by way of the open two port, two position valves 18 and 19. The brakes are applied.

A pressure builds up in the pressurechange chamber 13 and, acting as a reaction pressure, increases until the level of the control pressure in the control chamber 12' is attained. By virtue of the equilibrium of forces obtained on the control diaphragm 12, the spring-loaded valve plunger 10 can move towards, and reach, the valve seat 7.

When in this position, the diaphragm 12 is resting on the valve seat 14. Thus, lines and chambers under the supply pressure, the brake cylinder pressure and the venting or atmospheric pressure are isolated from one another.

If the control pressure below the control diaphragm 12 is reduced, for example by way of the brake valve 2 or, alternatively, by way of the solenoid valve 30, the reaction pressure in the chamber 13 immediately predominates and moves the control diaphragm 12 away from the valve seat 14, so that the reaction pressure and thereby, when the two-position valves 18, 19 are not shut off, also the brake pressure in the brake cylinders 24 and 25, is reduced until the equilibrium of forces on the diaphragm 12 is re-established.

In addition to the regulation of the brake cylinder pressure by the control pressure, the brake cylinder pressure in the connected brake cylinders 24 and 25 can also be influenced by the two-position valves 18 and 19, which are controllable by the pilot-controlled solenoid valves 29 and 31, such that the brake pressures in the brake cylinders 24 and 25 can be shut off from the pressure-change chamber 13.

Since this shut-off function can be effected by the two-position valves 18 and 19 irrespective of the prevailing position (drop in pressure or build up of pressure) of the relay valve 9, the following pressure changes can be effected simultaneously: pressure drop in the two brake cylinders 24 and 25 pressure drop in one brake cylinder and -pressure maintained in the other brake cylinder pressure maintained in one brake cylinder and build-up of pressure in the other brake cylinder build-up of pressure in the two brake cylinders 24 and 25, to the same or differing levels.

Thus, by means of only one pressurecontrol valve unit 4, common, or, alternatively, individual wheel regulation can be performed in which, compared with the control valves normally used in individual wheel regulation, functional advantages are additionally obtained by virtue of the relay function.

Figs. 2 and 3 show diagrammatically two embodiments including the two-channel combined pressure-control valve unit of Fig. 1. These embodiments can also use a three-channel construction of pressurecontrol valve unit. The parts which are the same as those shown in Fig. 1 are provided with the same reference numerals.

Referring to Fig. 2, a supplementary three port, two position solenoid valve 51 is used and is also arranged in the housing of the pressure-control valve unit. Compressed air can be introduced into the control chamber 12' directly through the solenoid valve 30 by way of the supplementary solenoid valve 51 and an internal connection line 52. Consequently, brake pressure can be introduced into the connected brake cylinders by way of the solenoid valve 51 as well as by way of the brake valve 2. However, whilst the introduction of pressure by the brake valve 2 is effective at all axles, individual brake cylinders 24 and 25 can be controlled by way of the solenoid valve 51.

By way of example, drive slip regulation can be performed on the drive axle of a tractor vehicle by means of this one supplementary solenoid valve 51 and a relatively simple elaboration of the anti-skid logic. A spinning or slipping wheel, which the anti-skid logic can detect by way of wheel sensors, is braked by way of the solenoid valve 51, and at the same time a build-up of the brake pressure of a nonslipping wheel can be prevented by simultaneously shutting off the associated two port, two position valve 18 or 19. By regulating the two wheels to the same amount of slip or the same rotational speed, the action of a mechanical differential lock can be accurately obtained, but at considerably reduced expense.

Readiness for slip regulation can be initiated by the driver in a conventional manner, by means of, for example, a switch or, alternatively, automatically by the elaborated anti-skid logic which detects a spinning or slipping wheel by means of a positive slip threshold switch circuit and triggers the automatic slip regulation.

It will be appreciated that the solenoid valve 51 need not be arranged directly in the combined pressure-control valve unit as is shown in Fig. 2. Alternatively, as is shown in Fig. 3, it can be located as solenoid valve 51' anywhere in the vehicle.

Instead of using a solenoid valve, in the embodiment of Fig. 4 the controlled introduction of pressure into the individual brake cylinders can also be effected by means of a normal, mechanically operated three port, two position supplementary valve 53 which can be engaged by, for example, the driver by means of a handle 54 whenever the drive slip regulation is required.

In the embodiment of Fig. 5 the supplementary valve 53 is provided with a locking button 55 having a withdrawable key, instead of the handle 54, whereby the three port, two position supplementary valve can additionally provide an anti-theft safeguard which, in a simple manner, prevents or at least hinders theft of the vehicle through a single operation causing full reservoir brake pressure to be continuously applied to the connected brake cylinders.

In the embodiment of Fig. 6 a vehicle has two pressure-control valve units 56 and 57 for vehicles axles 58, 59 respectively. In this instance, the pressure-control valve units 56 and 57 are not in the form of relay valves, but are switch valves having an on-off function. Alternatively, the two-channel valves illustrated may each be in the form of two single-channel valve units.

A three port, two position supplementary valve 60 is constructed with a throttle 61 in its change-over position, so that the buildup of supply pressure is effected more slowly when the three port, two position supplementary valve 60 is changed over than when the valve is not actuated.

WHAT WE CLAIM IS: 1. A pressure-control valve assembly for an anti-skid system for wheel brakes of motor vehicles, comprising a valve unit in which a three port, two position valve responsive to a control pressure, is provided for a single- or multi-channel control, and a two port, two position valve is provided for each channel, in combination with a supplementary three port, two position valve connected to a brake valve control line and a compressed air supply line.

2. A pressure-control valve assembly as claimed in claim 1, in which the supplementary three port, two position valve is a solenoid valve which, when in its de-engergized state, can establish communication between the brake valve control line and a control chamber for receiving the control pressure and, when in its energized state, control pressure can be introduced into the said control chamber by way of the compressed air supply line.

3. A pressure-control valve assembly as claimed in claim 1 or 2, in which the supplementary three port, two position valve is arranged outside a bottom portion of the housing of the valve assembly.

4. A pressure-control valve assembly as claimed in any of claims 1 to 3, in which the supplementary three port, two position valve, is operable mechanically.

5. A pressure-control valve assembly as claimed in claim 4, in which the supplementary three port, two position valve is operable by means of a handle or by means of a locking button.

6. A pressure-control valve assembly as claimed in any of claims 1 to 5, in which anti-slip regulation can be performed by

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. same as those shown in Fig. 1 are provided with the same reference numerals. Referring to Fig. 2, a supplementary three port, two position solenoid valve 51 is used and is also arranged in the housing of the pressure-control valve unit. Compressed air can be introduced into the control chamber 12' directly through the solenoid valve 30 by way of the supplementary solenoid valve 51 and an internal connection line 52. Consequently, brake pressure can be introduced into the connected brake cylinders by way of the solenoid valve 51 as well as by way of the brake valve 2. However, whilst the introduction of pressure by the brake valve 2 is effective at all axles, individual brake cylinders 24 and 25 can be controlled by way of the solenoid valve 51. By way of example, drive slip regulation can be performed on the drive axle of a tractor vehicle by means of this one supplementary solenoid valve 51 and a relatively simple elaboration of the anti-skid logic. A spinning or slipping wheel, which the anti-skid logic can detect by way of wheel sensors, is braked by way of the solenoid valve 51, and at the same time a build-up of the brake pressure of a nonslipping wheel can be prevented by simultaneously shutting off the associated two port, two position valve 18 or 19. By regulating the two wheels to the same amount of slip or the same rotational speed, the action of a mechanical differential lock can be accurately obtained, but at considerably reduced expense. Readiness for slip regulation can be initiated by the driver in a conventional manner, by means of, for example, a switch or, alternatively, automatically by the elaborated anti-skid logic which detects a spinning or slipping wheel by means of a positive slip threshold switch circuit and triggers the automatic slip regulation. It will be appreciated that the solenoid valve 51 need not be arranged directly in the combined pressure-control valve unit as is shown in Fig. 2. Alternatively, as is shown in Fig. 3, it can be located as solenoid valve 51' anywhere in the vehicle. Instead of using a solenoid valve, in the embodiment of Fig. 4 the controlled introduction of pressure into the individual brake cylinders can also be effected by means of a normal, mechanically operated three port, two position supplementary valve 53 which can be engaged by, for example, the driver by means of a handle 54 whenever the drive slip regulation is required. In the embodiment of Fig. 5 the supplementary valve 53 is provided with a locking button 55 having a withdrawable key, instead of the handle 54, whereby the three port, two position supplementary valve can additionally provide an anti-theft safeguard which, in a simple manner, prevents or at least hinders theft of the vehicle through a single operation causing full reservoir brake pressure to be continuously applied to the connected brake cylinders. In the embodiment of Fig. 6 a vehicle has two pressure-control valve units 56 and 57 for vehicles axles 58, 59 respectively. In this instance, the pressure-control valve units 56 and 57 are not in the form of relay valves, but are switch valves having an on-off function. Alternatively, the two-channel valves illustrated may each be in the form of two single-channel valve units. A three port, two position supplementary valve 60 is constructed with a throttle 61 in its change-over position, so that the buildup of supply pressure is effected more slowly when the three port, two position supplementary valve 60 is changed over than when the valve is not actuated. WHAT WE CLAIM IS:

1. A pressure-control valve assembly for an anti-skid system for wheel brakes of motor vehicles, comprising a valve unit in which a three port, two position valve responsive to a control pressure, is provided for a single- or multi-channel control, and a two port, two position valve is provided for each channel, in combination with a supplementary three port, two position valve connected to a brake valve control line and a compressed air supply line.

means of the supplementary three port, two position valve in combination with anti-skid logic.

7. A pressure-control valve assembly as claimed in any of claims 3 to 6, in which safeguard against theft can be obtainable by means of the supplementary three port, two positive valve.

8. A pressure-control valve assembly as claimed in any of claims 1 to 7, in which a throttle is provided in the supplementary three port, two position valve whereby a build-up of supply pressure can be delayed when the said valve is in its changed-over position.

9. A pressure-control valve assembly for wheel brakes of motor vehicles comprising a valve unit in combination with a supplementary valve, constructed and arranged and adapted to operate substantially as hereinbefore particularly described with reference to and as illustrated in Fig. 2, or Fig. 3, or Fig. 4, or Fig. 5, of Fig. 6 of the accompanying drawings.