Anti-blocking control system

An anti-blocking control system for a vehicle with two brake circuits, in which the regulation of the brake pressure is achieved either at a wheel and/or the wheels of an axle by both brake circuits and in which the pressure generated in this manner at the wheel(s) is jointly varied in case of a tendency to block. In order to simplify this brake pressure variation, a valve arrangement is used, consisting of a magnetic member with a coil and an armature as well as of a valve member having two separate valves disposed in the brake lines to the wheel(s). These two valves are jointly operated by the magnetic member.

BACKGROUND OF THE INVENTION 
The present invention relates to an anti-blocking control system for a 
vehicle with dual brake circuits, wherein brake pressure is generated by 
means of both brake circuits at one and/or both wheels of an axle of the 
vehicle, the brake circuits consisting of data transmitters assigned to 
the wheels of the vehicle for the determination of the wheel movement 
attitude, of an analytic circuit to which the signals from these data 
transmitters are sent and which transforms them to brake pressure control 
signals, and of control valves for the control of the brake pressure at 
the wheel brakes. The brake pressure at the wheel(s) is varied jointly for 
both brake circuits. 
While, by virtue of the use of the presently common joint variation of the 
brake pressure at the brakes of the rear axle, for instance in accordance 
with the so-called "select-low" operation, a considerable savings is 
realized when compared with the 4-wheel control (only one valve and one 
output stage for their control), when the brake circuits are split between 
the front and rear wheels, so far two valves are needed for the control of 
the brake pressure at the wheels of the rear axle of a vehicle with 
diagonal brake circuit division, because of the separation of the brake 
circuits. For reasons of safety it is even necessary to control these 
valves via separate output stages, since otherwise a defect at a valve 
coil cannot be detected, except with considerable effort, and a 
single-circuit control during such a defect is not permissible. 
This also holds for brake circuit divisions in which the wheel brake is 
operated by way of both brake circuits. 
OBJECT AND SUMMARY OF THE INVENTION 
The present invention is designed to reduce the outlay necessary for the 
common control in vehicles with such a brake circuit division. 
Besides the advantages of a synchronous pressure control at both wheels and 
the savings of an output stage, inclusive of control line and of a magnet, 
space is saved in addition. 
In the embodiment in accordance with the present invention, the valves are 
preferably constructed as multiposition valves, especially triple position 
valves, wherein the magnet can be charged with differently staged output 
for the control of the several positions and wherein the electromagnet 
and/or the valves contain socalled pre-positioned barrier springs, which 
only begin to act after the intermediate position has been reached. The 
control output and the force of these springs have to be adjusted to each 
other in such a manner that with a predetermined control output the valves 
reach a determined position. 
The valves can be embodied as slide valves or as seat valves. Furthermore, 
the invention can also be used for brake systems with direct activation of 
a main brake cylinder (open systems) or for full power systems (closed 
systems). 
The invention will be better understood and further objects and advantages 
thereof will become more apparent from the ensuring detailed description 
of preferred embodiments taken in conjunction with the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In FIG. 1, the front wheels are designated 1 and 2 and the rear wheels 3 
and 4. A solidly drawn brake circuit leads from a main brake cylinder 5 to 
the wheels 2 and 3 and a brake circuit drawn with dotted lines leads to 
wheels 1 and 4. Magnetic control valves 6 and 7 are disposed in the brake 
lines leading to the front wheels 1 and 2. In the brake lines leading to 
the rear wheels, however, the double valve 8, built according to the 
present invention, is disposed. Brake pressure control signals are brought 
to the three valves 6-8 by an analytic element 9, which receives signals 
derived from well known data transmitters 41-44 located relative to each 
wheel in order to determine the wheel movement attitude of the wheels 1-4. 
FIG. 2 shows a possible embodiment of the double valve 8 of FIG. 1. It 
consists of a block 10, which has two triple position slide valves built 
in, and of an electromagnet 11 disposed thereon. 
The electromagnet 11 comprises a cup-shaped stator 12 with a coil 13 and an 
armature 14 disposed therein. The armature 14 is equipped with a plunger 
15 placed axially movable on the stator 12, which transfers the movements 
of the armature to a plate 16. A barrier spring 18, fastened between the 
armature 14 and a disc 17, fastened to the plunger, surrounds the plunger 
15. The valves, which are operated by the armature 14 via the plate 16, 
each comprises two slides 20 and 21, connected by a rod 19, which are 
mutually slidable in the bore 22, and of a return spring 23. The bore 22 
has three connectors 24-26, which are connected with the main brake 
cylinder (24), the wheel brake cylinder (25) and the return line (26). 
In the starting position the connectors 24 and 25 are connected to each 
other. This makes pressure generation possible. If the coil 13 is charged 
with a first (small) control output, the armature 14 with the plunger 15 
moves downwardly until the disc 17 touches the stator 12. The control 
output is insufficient to overcome the force of the barrier spring 18, 
which can be tensioned even more by the displacement of the disc 17 
relative to the plunger 15. In this intermediate position the slide 20 
closes the connection between the connectors 24 and 25, and the connection 
of the connectors 25 and 26 remains interrupted by the slide 21 (keeping 
the pressure constant). 
Only when by means of a higher control output the force of the barrier 
spring 18 is overcome and the armature 14 is moved further until it firmly 
touches the stator 12, -with continued interruption of the connection 
between the connectors 24 and 25-the connection between the connectors 25 
and 26 are opened, so that pressure release can take place. The 
construction of the valve slide is kept especially simple in view of its 
small size. Instead of the normal annular grooves for pressure relief, the 
diameter of the connecting line has been chosen to be larger than the 
diameter of the slide. This assures a simple pressure relief method. 
Furthermore, the slide gasket is outwardly stressed by only relatively low 
pressure, which results in small displacement forces. 
In FIG. 3 part of the drawing of FIG. 2 is shown, namely parts 15', 16' and 
20', corresponding to parts 15, 16 and 20. However, now the barrier spring 
18' is shown surrounding the slide 20' and fastened between the plate 16' 
and the disc 17'. 
A vehicle with a different brake circuit division is shown in FIG. 4, for 
which the present invention is also usable. Here the brake pressure at the 
front wheels 30 and 31 is derived from the two brake circuits 32 and 33, 
wherein the brake circuits remain separated from one another. The brakes 
of the rear wheels 34 and 35 are also operated from separate brake 
circuits 32 and 33. In this case three dual-valve arrangements 36 to 38, 
designed in accordance with the present invention, can be used, since the 
brake pressure at the single wheels 30 and 31 as well as at the wheels 
34/35 of the rear axle, coming from separate brake circuits, is intended 
to be commonly controlled. 
The foregoing relates to preferred exemplary embodiments of the invention, 
it being understood that other embodiments and variants thereof are 
possible within the spirit and scope of the invention, the latter being 
defined by the appended claims.