GB1579301A

GB1579301A - Anti-skid systems for motor vehicles

Info

Publication number: GB1579301A
Application number: GB1766878A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1977-09-02
Filing date: 1978-05-04
Publication date: 1980-11-19
Also published as: DE2739513C2; JPS5449470A; DE2739513A1; JPS6318538B2; FR2401804A1; FR2401804B1

Description

(54) IMPROVEMENTS IN OR RELATING TO ANTI-SKID SYSTEMS FOR MOTOR VEHICLES (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 anti-skid systems for motor vehicles.

In one known anti-skid system for brake systems of motor vehicles having at least two pressure controlled main valves and a solenoid pilotcontrol valve for each main valve the individual members of the system are adjusted to their operational behaviour, although their operational reliability leaves much to be desired, at least under extreme operating conditions. Thus, satisfactory functioning of the valves is not always ensured in the case of wet roads or in the-case of low temperatures in winter. The draining of the brake pressure control valves involves considerable expense in conventional compressed-air brake systems.However, the formation of condensate, promoted by the rapid pressure-change, is intensified particularly in anti-skid systems, and, in addition to the corrosive action, can result in the risk of freezing during winter and thus possibly lead to complete operational failure.

According to the present invention there is provided an-anti-skid system for the brake system of motor vehicles in which at least two pressure-controlled main valves and a solenoid pilot-control valve for each main valve are provided in a common housing which has a single common atmospheric air connection for all the valves and is adapted to be mounted on a vehicle such that the solenoid pilotcontrol valves are below the main valves and the common atmospheric air connection is on the underside of the housing.

An anti-skid system embodying the present invention can have the advantage that water collecting in the pressure-controlled valve assembly can be reliably discharged to the outside, so that the valve assembly cannot fail as-a result of corrosion and/or freezing. Control chambers of the main valves, and the solenoid pilotcontrol valves, can be so arranged on the pressurecontrol valve that water of condensation which is produced is conveyed to the atmosphere solely by gravity by way of an atmospheric air connection below the solenoid valves.

Furthermore, passages in the pressurecontrolled valve are arranged in a special manner which effectively prevents the accumulation of water, and a preferred arrangement of the main valves results in a very compact construction, which also facilitates the discharge of water.

The-invention will be further described-by way of example with reference to the accompanying drawings in which: Figure 1 is a diagrammatic illustration of a brake system having an anti-skid system according to one embodiment of the invention and showing a pressure-control valve assembly in section; Figure 2 is a side elevation, partially in section, of the pressure-control valve assembly of Figure 1, and Figure 3 is-an inverted plan view of the pressurecontrol valve assembly of Figure 1.

An anti-skid system for brakes is incorporated in a brake line 1, 1', 1", between a brake valve 2 and two wheel brake cylinders 3 and 4.

The anti-skid system comprises two sensors 5 and 6 on the wheels 7 and 8 of a vehicles axle 9, an electronic control device 10 to which are connected the sensors 5 and 6 and also three solenoid valves 11, 12 and 13, only two of the solenoid valves being shown in Figure 1, since the third solenoid valve is located behind the first solenoid valve (see Figure 3).

The three solenoid valves 11,12 and 13 are pilotcontrol valves and, together with three main valves 14, 15 and 16, are combined in a common housing 17 to form a so-called pressure-control valve assembly. The housing 17 basically bipartite and has an upper portion 18 and a lower portion 19 which are clamped to gether by means of a bolted connection having bolts 20.

The three pilotcontrol valves 11, 12, 13 have housings 21,22 and 23 each having a mounting surface 21', 22', and 23' respectively by means of which the housings abut against an under-surface 24 of the upper portion 18 and are secured at this location by the aforementioned bolted connection of the housing portions 18 and 19. A push rod 25,26 and 27 (the third push rod is not shown) of the solenoid pilotcontrol valve 11, 12 and 13 respectively passes through each mounting surface 21 ',22' and 23' respectively, and the top ends of the push rods are provided with valve closure members 28,29 and 30 respectively for respective valve seats 31,32 and 33 (the third closure member and the third valve seat are not illus trated).

Each valve closure member 28, 29 and 30 controls communication between a respective branch passage 34, 35, 36 (the third one is not illustrated) and a respective passage 40, 41 , 42 leading to a respective working chamber 37,38, 39 (the third one is not illustrated) of the three main valves 14, 15 and 16.

The upper portion 18 of the housing has, for the brake line portion 1, an inlet connection 43 having a bore extension 44 which is intersected above the lowest level of its transverse cross section by the branch passages 34,35 and 36 which commence from here. An atmospheric air connection leads downwardly from the working chambers 37,38,39 of the three main valves 14, 15 and 16 by way of passages 40,41, 42 through the housings 21,22,23 of the solenoid valves 11, 12 and 13, and then outwardly.

The atmospheric air connection, common to all the valves, is provided on the underside of the housing 17. This atmospheric air connection is in the form of an outwardly opening non-return valve 45.

The main valves 14, 15 and 16 in the upper portion 18 of the housing are two inlet valves 15 and 16 (Figure 2) and an outlet valve 14 (Figure 1). The axes of the main valves 14,15 and 16 are horizontal and are disposed at angles to one another, so that the two main inlet valves 15 and 16 are located opposite one another on a common axis, and the axis of the main outlet valve 14 is at right angles thereto.

Thus, it is possible for the valve unit to be of very compact construction. Furthermore, owing to the fact that water drains off down 'wardly, the axis of the main outlet valve 14 is disposed higher than those of the other two main valves 15 and 16.

The three main valves 14,15 and 16 are fitted in housing recesses 46,47,48 which are all externally sealed by identical covers 49, 50 and 51. Furthermore, the two main inlet valves 15 and 16 are each provided with a pressurecontrolled actuating diaphragm 52, 54 in part defining the working chamber 38, 39 respectively, and a valve closure member diaphragm 53, 55 respectively, the diaphragms being identical. Furthermore, an actuating diaphragm 56 of the main outlet valve 14 is identical to the said diaphragms 52 to 55.

In contrast to the main inlet valves 15 and 16, the main outlet valve 14 has a valve closure plate 72 which is designed to cooperate with two valve seats 57 and 58 and is urged towards one valve seat 58 by the action of a spring 59.

The respective valve seats 60 and 61 of the two main inlet valves 15 and 16, and one valve seat 57 of the main outlet valve 14, communicate with the brake line portion 1, and chambers 62, 63, located respectively between the valve seat 60, 61 and the diaphragms 53, 55 are connected by way of respective passages 64, 65 (see Figure 2) to the brake line portions 1' and 1" respectively and, by way of the latter, to the brake cylinders 3 and 4 respectively.

As will be seen from the inverted plan view of Figure 3, the three solenoid pilot control valves 11, 12 and 13 are arranged at three corners 66, 67 and 68 of a rectangle. A plug 70 (see also Figure 2), required for establishing electrical lead connections, is located at the fourth corner 69.

It may also be mentioned that the two main inlet valves 15 and 16 are two port, two position valves by means of which the passage through the brake line is either shut off or kept open. On the other hand, the main outlet valve 14 is a three port, two position valve which controls the passage through the brake line on the one hand and, on the other hand, an almost pheric air connection. The main valve 14 is provided with an annular passage 71 which is connected to the inlet connection 43 and the brake line portion 1 and which is intersected by the branch passages 34 and 36 above its lowest level and which communicates with the inlet connection 43 only at its uppermost level.

The system described operates as follows: During normal braking, a free brake line passage exists between the brake valve 2 and the brake cylinders 3 and 4 by way of the brake line 1, 1' and 1", wherein the braking air flows to the brake cylinders 3 and 4 by way of the three port, two position main valve 14 and the two port, two position main inlet valves 15, 16 respectively.

The anti-skid device responds when a wheel, such as the wheel 7 with brake cylinder 3,is over-braked, and the pilotcontrol valves 11 and 13 change over. The three port, two position main outlet valve 14 is thereby changed over and allows air to flow to the atmosphere from the brake cylinder 3. The two port, two position main inlet valve 16 at the same time switches to its closed position, so that the pressure is maintained in the brake cylinder 4 which is not tending to lock. All the pilot-control valves 11, 12 and 13 change over at the end of the pressure drop phase of brake cylinder 3.

The three port, two position main valve 14 and the two port, two position main valve 15 change over to allow the passage of air, the pressure in the brake cylinder 4 continues to increase, and the two port, two position main valve 15 switches to its closed position, so that the reduced brake pressure in the brake cylinder 3 is maintained. The pilotcontrol valve 12 closes again after a certain period of time at the end of the holding phase, so that the main valve 15 again assumes its initial position for an increase in pressure. The reduced brake pressure in the brake cylinder 3 is increased again in a pulsed manner by the switching-on and switching-off of the pilotcontrol valve 12.

It is advantageous that the reduction of the brake pressure and the build-up of the brake pressure of the two brake cylinders 3 and 4 are effected in common by means of the three port, two position main valve 14, and that the common brake pressure modulation thus effected can be interrupted by pressurizing and venting the brake cylinders 3 and 4 at any time by means of the two port, two position valves 15 and 16 connected in series with the respective brake cylinders and downstream of the main valve 14. Thus, despite economising on one valve compared with a system having individual wheel regulation it is possible to control each of the two brake cylinders 3 and 4 individually.It is only during the phase of pressure reduction in one brake cylinder 3 or 4 that the build-up of pressure in the other brake cylinder is interrupted by a holding phase for the short duration of the pressure drop phase.

It will be appreciated that it is also possible to reduce the pressure in the two brake cylinders 3 and 4 simultaneously by means of the proposed system.

Figures 1 and 2 show that the passage of the braking air and the exhaust air is switched such that scarcely any water can remainin the housing 17. The main valves 14, and 16 are arranged horizontally, the pilotcontrol valves 11,12 and 13 are located below the main valves 14, 15 and 16, and the perpendicular branch passages 34,35 and 36 open into the main passage (bore extension 44) at an elevated level, so that any water accumulating in the main passage cannot fill the branch passages 34, 35 and 36, and, finally, two of three pilotcontrol valves 11, 12 and 13 are fed by way of the annular passage 71 which is only connected at its uppermost level to the inlet connection 43 and which is intersected by the branch passages 34 and 36 above its lowest level.As a re snlt of this, and owing to the short connection passages resulting from the compact arrangement, the valve assembly is substantially protected from any freezing accumulations of water.

Alternatively, it is possible to perform singlechannel control instead of the twochannel control described. Only a three port, two position and a single two port, two position main valve and only two solenoid pilotcontrol valves are then required in the valve assembly.

The two brake cylinders of one axle are then controlled in the same manner; WHAT WE CLAIM IS: 1. An anti-skid system for the:brake system of motor vehicles, in which at least two pressurecontrolled main-valves and a solenoid pilotcontrol valve for each main valve are provided in a common housing which has a single common atmospheric air connection for all the valves and is adapted to be mounted own a vehicle such that the solenoid piloteontrol valves are below the main valves and the common atmospheric air connection is on the underside of the housing.

2. An anti-skid system as claimed in claim 1, in which each solenoid pilotcontrol valve controls communication between a working chamber of its associated pressurecontrolled main valve and either a brake line inlet connection for connection to a brake valve or the atmospheric air connection, and in which communication between the brake line inlet connection and a respective solenoid valve is established by way of a respective branch passage which commences above the lowest level of the transverse cross section of the brake line inlet connection.

3. An anti-skid system as claimed in claim 1 or 2, in which the axes of the main valves are arranged at angles to one another.

4. An anti-skid system as claimed in claim 3, having three main valves, of which two main valves are located opposite to one another on a common axis, whilst the axis of a third main valve is arranged at right angles thereto.

5. An anti-skid system as claimed in claim 4, in which said two main valve is an outlet valve.

6. An anti-skid system as claimed in claim 4 or 5, in which the axis of the third main valve is located in a different plane from that of said two main valves.

7. An anti-skid system as claimed in claim 6, in which the axis of the third main valve is arranged higher than the common axis of the said.lwo main valves.

8. An anti-skid system as claimed in any of claims 1 to 7, in which the main valves are disposed in housing recesses which are externally sealed by identical covers.

9. An anti-skid system as claimed in claim 8, in which each of said two main valves has a pressure-controlled actuating diaphragm and a valve closure member diaphragm and the two diaphragms of each of said two main valves are identical.

10. An anti-skid system as claimed in any of the claims 1 to 9, in which the common housing has an upper portion and a lower portion, and the lower portion is of cup-shaped construction and has an outwardly opening nonreturn valve as the common atmospheric air connection for all the valves.

11. An anti-skid system as claimed in any of the claims 1 to 10, in which three pilot-control valves are arranged on the underside of the housing together with a plug for electrical lead

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

Claims

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

change over to allow the passage of air, the pressure in the brake cylinder 4 continues to increase, and the two port, two position main valve 15 switches to its closed position, so that the reduced brake pressure in the brake cylinder 3 is maintained. The pilotcontrol valve 12 closes again after a certain period of time at the end of the holding phase, so that the main valve

15 again assumes its initial position for an increase in pressure. The reduced brake pressure in the brake cylinder 3 is increased again in a pulsed manner by the switching-on and switching-off of the pilotcontrol valve 12.

It is advantageous that the reduction of the brake pressure and the build-up of the brake pressure of the two brake cylinders 3 and 4 are effected in common by means of the three port, two position main valve 14, and that the common brake pressure modulation thus effected can be interrupted by pressurizing and venting the brake cylinders 3 and 4 at any time by means of the two port, two position valves 15 and 16 connected in series with the respective brake cylinders and downstream of the main valve 14. Thus, despite economising on one valve compared with a system having individual wheel regulation it is possible to control each of the two brake cylinders 3 and 4 individually.It is only during the phase of pressure reduction in one brake cylinder 3 or 4 that the build-up of pressure in the other brake cylinder is interrupted by a holding phase for the short duration of the pressure drop phase.

It will be appreciated that it is also possible to reduce the pressure in the two brake cylinders 3 and 4 simultaneously by means of the proposed system.

Figures 1 and 2 show that the passage of the braking air and the exhaust air is switched such that scarcely any water can remainin the housing 17. The main valves 14, and 16 are arranged horizontally, the pilotcontrol valves 11,12 and 13 are located below the main valves 14, 15 and 16, and the perpendicular branch passages 34,35 and 36 open into the main passage (bore extension 44) at an elevated level, so that any water accumulating in the main passage cannot fill the branch passages 34, 35 and 36, and, finally, two of three pilotcontrol valves 11, 12 and 13 are fed by way of the annular passage 71 which is only connected at its uppermost level to the inlet connection 43 and which is intersected by the branch passages 34 and 36 above its lowest level.As a re snlt of this, and owing to the short connection passages resulting from the compact arrangement, the valve assembly is substantially protected from any freezing accumulations of water.

Alternatively, it is possible to perform singlechannel control instead of the twochannel control described. Only a three port, two position and a single two port, two position main valve and only two solenoid pilotcontrol valves are then required in the valve assembly.

The two brake cylinders of one axle are then controlled in the same manner; WHAT WE CLAIM IS: 1. An anti-skid system for the:brake system of motor vehicles, in which at least two pressurecontrolled main-valves and a solenoid pilotcontrol valve for each main valve are provided in a common housing which has a single common atmospheric air connection for all the valves and is adapted to be mounted own a vehicle such that the solenoid piloteontrol valves are below the main valves and the common atmospheric air connection is on the underside of the housing.
2. An anti-skid system as claimed in claim 1, in which each solenoid pilotcontrol valve controls communication between a working chamber of its associated pressurecontrolled main valve and either a brake line inlet connection for connection to a brake valve or the atmospheric air connection, and in which communication between the brake line inlet connection and a respective solenoid valve is established by way of a respective branch passage which commences above the lowest level of the transverse cross section of the brake line inlet connection.
3. An anti-skid system as claimed in claim 1 or 2, in which the axes of the main valves are arranged at angles to one another.
4. An anti-skid system as claimed in claim 3, having three main valves, of which two main valves are located opposite to one another on a common axis, whilst the axis of a third main valve is arranged at right angles thereto.
5. An anti-skid system as claimed in claim 4, in which said two main valve is an outlet valve.
6. An anti-skid system as claimed in claim 4 or 5, in which the axis of the third main valve is located in a different plane from that of said two main valves.
7. An anti-skid system as claimed in claim 6, in which the axis of the third main valve is arranged higher than the common axis of the said.lwo main valves.
8. An anti-skid system as claimed in any of claims 1 to 7, in which the main valves are disposed in housing recesses which are externally sealed by identical covers.
9. An anti-skid system as claimed in claim 8, in which each of said two main valves has a pressure-controlled actuating diaphragm and a valve closure member diaphragm and the two diaphragms of each of said two main valves are identical.
10. An anti-skid system as claimed in any of the claims 1 to 9, in which the common housing has an upper portion and a lower portion, and the lower portion is of cup-shaped construction and has an outwardly opening nonreturn valve as the common atmospheric air connection for all the valves.
11. An anti-skid system as claimed in any of the claims 1 to 10, in which three pilot-control valves are arranged on the underside of the housing together with a plug for electrical lead

connections.
12. An anti-skid system for the brake systems of motor vehicles, constructed and arranged and adapted to operate substantially as hereinbefore particularly described with reference to and as illustrated in the accompanying drawings.