DE2327508A1 - VEHICLE BRAKING SYSTEM - Google Patents

Description

TELDIX Gm b H
6900 Heidelberg
Grenzhöfer Weg 36

Heidelberg, the 24th shark 1973 E / Pt-Ka / Pr E-287

Vehicle braking system

The invention relates to a vehicle brake system for at least one vehicle i-ad. at which a pulp actuation device provided that one of the hatred the brake actuation dependent first electrical signal generated, in which a brake pressure source is provided is, in which a valve arrangement is switched on in the connection between the brake pressure source and the wheel brake which temporarily establishes the connection between the brake pressure source and the wheel brake cylinder and for the purpose of reducing the pressure on the wheel brake cylinder temporarily connects it to an outlet.

State of the art:

The vehicle brakes commonly used today <- this applies to brake systems with pedal-operated master brake cylinders or brake boosters and to so-called Fuil-power systems - control the wheel brakes Brake pressure, which depends solely on the degree of brake actuation

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depends, with changes "in the braking system, such as Brake lining wear or changes in the elongation properties of the brake lines, loading of the vehicle, Coefficient of friction in the brake, etc., a change effect of the ratio of brake actuation to brake pressure.

So-called electrical brake systems are also known, which depend on the brake actuation on the wheel brake adjust a certain brake pressure (OS 2 128: 169). This requires a brake pressure measuring device Device, the signal of which is compared with the signal generated by the brake actuation device, the the signal generated by the comparison causes the pressure control.

Task and solution:

In contrast, the invention is based on the object to design this vehicle brake system © so that one a certain amount of brake actuation a certain vehicle deceleration is equivalent to.

This object is achieved by the features specified in claim 1. The brake system according to the invention can be designed hydraulically or pneumatically.

The brake system according to the invention accordingly has the advantage that it controls a brake pressure that of the corresponds to the vehicle deceleration required by the amount of brake actuation. Depending on the coefficient of friction in the Different pressures are applied to the brakes to achieve this vehicle deceleration. The those Vehicle deceleration determining device can in be designed in some way, e.g. B. a facility be, in which a mass moves as a function of the deceleration, which changes a resistance or by approaching a magnet

Deemflusst magnetic field sensitive member / or via one of the

■ Mass operated pulse wheel direct digital signals

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generated. The generated signal can be an analog signal or be a digital signal, and also, the comparison can be analog or digitally.

Advantageous further training:. ·

To prevent the failure of the brake pressure source, one pump - possibly with a connected storage chamber - Can be, a failure of the brake system occurs, is according to a development of the invention a piston connected to the brake actuation device, which is movable in a cylinder "- the one with the wheel brake cylinder communicates. This piston "is when actuated the brake actuator moved beyond a certain amount and then together with the cylinder represents an emergency brake pressure generator. In this case, the connection between brake pressure - source and wheel brake cylinder.interrupted «With the appropriate Activation of the cylinder space in the line between the brake pressure source .. and the wheel brake cylinder is only achieved by the displacement of the piston that a closed system between the emergency pressure generator and the Wheel brake is effective, so that a fixed volume between these elements is included. However, according to a development of the invention, in particular if the emergency pressure generator is connected in the shunt is also a separate additional valve device provide that between the first valve device and the wheel brake cylinder is switched on, which is due to a piston displacement, in particular via a mechanical Connection is actuated. The actuation of the valve can according to another possibility, also when the pressure of the brake pressure source drops below a predetermined value, for which purpose the valve is preferably carried out is designed as a pressure-controlled valve. The valve device causing the pressure control can can also be combined with the further valve device.

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The brake actuation device is preferably designed in such a way that, as the pedal travel increases, that of the brake actuation counteracting force disproportionately, e.g. B. increases square or parabolic. Furthermore can the system is designed so that the rate of pressure rise depends on the pedal speed in such a way that as the pedal speed increases, the rate of pressure increase also increases. In This can easily be achieved by providing pulsed signals for actuating the valve arrangement generated and. the duty cycle of these pulsed signals changes.

In the same way, the rate of pressure change can be changed as a function of the vehicle speed, the rate of pressure change the greater the vehicle speed, the lower it is. According to a further development of the invention there is first a pressure increase at a given speed for a given time, which if necessary can also be dependent on other variables (pressure), and only then does fine control of the pressure change set according to the vehicle deceleration (rate of change = f (v'-p).

It should also be mentioned that you can use the vehicle deceleration sensor if necessary or its signals to eliminate rapid changes, e.g. due to bumps, must dampen. If the amount of brake actuation changes, this damping is preferably ineffective made.

The combination of the braking system according to the invention with an anti-lock regulator is particularly advantageous, whereby a known arrangement for brake pressure variation in the connection between the valve assembly

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voltage and brake cylinder or the emergency pressure generator and the brake cylinder is switched on. This arrangement for brake pressure variation, which is determined by an electrical control circuit when a wheel tends to lock is actuated, a modulator (an arrangement that interrupts the connection to the wheel brake cylinder and the "volume for the enclosed Pressure medium can vary) or a valve arrangement that increases the pressure depending on the switching position and lowering the pressure and possibly keeping the pressure constant. Of particular advantage it is when the decelerator can also be used within the anti-lock controller, ζ. B. according to an older proposal for monitoring the functionality of the anti-lock controller.

Up to now, the application of the braking system according to the invention to a vehicle wheel has been dealt with. It can can also be used with several wheels, whereby it is possible for all brake circuits of the vehicle to use a brake pressure source. Preferably is however, a number of emergency pressure generators corresponding to the number of brake circuits is provided, each of which one is assigned to a brake circuit. It is advantageous here to use the means for interrupting the connection between the brake pressure source and the wheel brake cylinder Provide piston displacement or lowering of the brake pressure for each brake circuit separately, since then with one Malfunction of the brake system two completely separate brake circuits are effective, so that in the event of a fault in one Circle the other circle remains intact.

As usual you can with the inclusion of several wheels Arrangements for brake pressure variation in the event of a tendency to blockage assign to the individual wheels or wheel groups;

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The existing measured value of the vehicle deceleration is favorably used brought to the vehicle driver by means of a corresponding display device for display and, if necessary possibly stored in connection with the initial brake speed for accident analysis.

Figure description;

An exemplary embodiment of the invention is shown in the drawing. The electrical lines are in this drawing made thinner than the hydraulic lines.

The pressure generator consists of the one according to the invention Exemplary embodiment consisting of an engine 1 which drives a pump that draws pressure medium from the reservoir 3. The pressure generator also includes a small pressure accumulator 4 ·, which is also designed as a pressure gauge at the same time can be. The pressure control switched on in the lines between the pressure generator and the wheel brake Valve arrangement 5 serving on the brakes is designed as a three-stage solenoid valve. It connects in the unexcited position shown, the wheel brake cylinders 6a and 7a of the front wheels 6 and 7 and the wheel brake cylinders 8a and 9a of the rear wheels 8 and 9 with the return line 10 leading to the reservoir 3 and thus holds the brakes depressurized. In another switch position, caused by a first control signal is effected, the line is disconnected and in a third it is caused by an additional switching signal Position, the pressure source is connected to the wheel brake cylinder. After the valve 10 there is a Separation into two brake circuits, namely one brake circuit for the front wheels 6 and 7 and one for the Rear wheels 8 and. 9. This division is only effective if the valves 11 and 12 in the not shown Position are switched, - what in the Ausführungsbeispiei then takes place when the pressure of the

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Pressure source 1-4- drops below a specified value, including the valves 11 and 12 as pressure-sensitive valves "of known design. In those of the valves 11 and 12 to the wheel brake cylinders 6a and 7a or 8a and 9a leading lines are beer for the Front wheels separate (13i 14 ·) and for the rear wheels a common solenoid valve 15 for pressure variation Blocking tendency switched on. These valves are also designed as three-stage valves that allow a pressure increase in the position shown, however can be switched to positions in which the pressure is on the wheel brake cylinders either kept constant or through Letting brake fluid flow out into the return line 10 is lowered. Instead of the three-stage valves would also be a combination of inlet and outlet valve or (without maintaining constant pressure) a three-way valve can be used.

Between valves 11 and 12 and the solenoid valves .13 to 15 is an emergency pressure generator for each brake circuit .In the form of a cylinder 16 or 17 is provided. In these Cylinders are arranged pistons 16a and 17a, the are held by springs 18 in the position shown.

A pedal 19 is provided for brake actuation, at the actuation of which a displacement of the part 22 opposes the force of the spring 20 comes about, whereby a signal in the encoder 21 is generated that of the measure the displacement and thus the applied force depends. For example, the transmitter can be based on the principle of differently influencing a magnetic field-sensitive Member, e.g. semiconductor sensitive to magnetic fields, work when a magnet approaches. That analog or digital output signal of the encoder is via the element 23, which can be used for signal adaptation, the * comparator 25 is supplied. Furthermore, a delay generator 26 is provided, which acts as a pendulum 26a and

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Receiver 26b is indicated. The signal that is dependent on the deflection and thus on the vehicle deceleration is also fed via an adapter 24- to the comparator 25, which is derived from the transmitter 21 in the case of a larger one Signal generates a first control signal, when the signals match, a second and when the signals are smaller Signal of the encoder "21 generates a signal O. By means of the AND gate 27 ensures that valve 5 can only be excited when the brake pedal is actuated. That Member 28 is a switch coupled to the pedal 19. With 29 is the control circuit for the valves 13 to 15, which for example via lines 30 rotational speed signals of attached to the wheels 6, 7 and 8/9, not shown speed sensor and via the lines 31 rotation delay signals of the Front wheels are fed and from these signals on the lines leading to the valves 13 to 15 Control signals generated for these valves.

On the panel 33, the vehicle speed is digitally displayed in the top line, in the middle line the correspondingly implemented (element 3 ² O vehicle deceleration and in the bottom line a malfunction of the braking system and / or anti-lock controller is displayed.

The system shown works as follows: If the pedal 19 is actuated, gate 27 is removed from the link prepared so that the output signal of the comparison element generated when the signal from the transmitter is larger, the valve 5 can bring into the position in which the brake pressure on the wheel brake cylinders increases. Due to the braking, the vehicle decelerates a corresponding signal from the transmitter 26 triggers. Does the vehicle deceleration correspond to that caused by the actuation of the pedal 19 required delay, a signal is generated in the comparator 25 that the valve

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til 5 brings into an intermediate position in which the pressure is kept constant (disconnected position). If the pedal actuation is reduced, the output signal of the comparison element 25 becomes zero and the valve 5 continues to operate into the switching position shown until the delay of the vehicle corresponds to the required deceleration.

Falls due to a system failure (leak, pump failure) if the pressure falls below a specified value, it switches the pressure-sensitive double valve 11/12 umund creates thus a common two-circuit braking system. The pistons 16 a and 17 a are used by the driver when the expected braking effect does not occur, moved by further actuation of the pedal 14 via the rod 35. This shift occurs when the part 22 has approximately reached the encoder 21, that is, after covering a predetermined one Way.

In both of the operating modes described, the individual wheels are subject to the locking tendency of the Control circuit 29 actuates the solenoid valves 1 $ to 15 and thereby the brake pressure on the wheel brake, the coefficient of friction adapted between tire and road. Of this is the pressure control by the valve 6 or the pistons 16a and 17a completely independent.

· -. Claims -

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Claims (12)

Claims ~ ',. ι .ιιιι.ι Λ, vehicle brake system for at least one vehicle wheel, V_ ^ in which a brake actuation device is provided which generates a first electrical signal dependent on the degree of brake actuation, in which a brake pressure source is provided, in which a valve arrangement is switched on in the connection between the brake pressure source and the wheel brake , which temporarily establishes the connection between the brake pressure source and the wheel brake cylinder and temporarily connects this to an outlet for the purpose of reducing the pressure on the bath brake cylinder, characterized in that a device which determines the vehicle deceleration is provided on the vehicle, which generates an electrical signal dependent on the vehicle deceleration and that Switching means are provided for comparing the signal dependent on the brake actuation and the signal dependent on the vehicle deceleration and for generating a control signal for the valve arrangement, such that a certain degree of brake actuation is a best immte vehicle deceleration is assigned. 2. Vehicle brake system according to claim 1, characterized in that that with the brake actuation device a piston in one with the wheel brake cylinder in connection standing cylinder is connected in such a way that when operated of the brake operating device beyond a predetermined extent, the piston and the cylinder as ÜDead brake pressure generators are effective. 3. Vehicle brake system according to claim 2 »characterized in that that means are provided that the connection between the brake pressure source and the wheel brake cylinder interrupt the piston displacement. / 11, 409851/0502 4. Vehicle brake systems according to claim 2 or 3, characterized characterized in that means are provided which establish the connection between the brake pressure source and the wheel brake cylinder when the pressure of the brake pressure source drops interrupt below a specified value. 5 · Vehicle brake systems according to claim 3 or 4, characterized characterized in that one on the pressure of the pressure source or the mechanical deflection of the brake actuator responsive valve switched into the connection between the valve arrangement and the wheel brake cylinder is. 6. Vehicle brake system according to one of claims 1 to 5 » characterized in that in the from the valve arrangement and / or the cylinder-piston arrangement to the wheel brake cylinder leading line an arrangement for modulating the brake pressure is switched on and that a control circuit for "influencing this arrangement is provided depending on the tendency of the wheel to lock. 7. Vehicle brake systems according to claim 6, characterized in that that the arrangement for modulation consists of a valve device which, depending on the switching position a pressure increase or pressure decrease and, if necessary allows a constant pressure. 8. Vehicle brake system according to one of claims 1 to 7i characterized by their application to several vehicle wheels. 9. Vehicle brake systems according to claim 8, characterized in that that when divided into several brake circuits, one pressure source is used for all circuits. / 12 409851/050 2 10. Vehicle brake system according to claim 2, 8 or 9, characterized. characterized in that a number of piston / cylinder assemblies corresponding to the number of brake circuits is provided ^ all are assigned to the brake circuits. 11. Vehicle brake system according to one of claims 3 or 5 and one of claims 8 to 10, characterized in that that the means for interrupting the connection between the brake pressure source and the wheel brake cylinder when the piston is displaced or lowering of the brake pressure are provided separately for each brake circuit. 12. Vehicle brake system according to one of claims 6 to 11, characterized in that arrangements for modulation of the brake pressure is provided for individual wheels and / or wheel groups depending on the tendency of the wheels to lock are. 13 · Vehicle brake system according to one of claims 1 to 12, characterized in that a display arrangement for Vehicle deceleration display is provided. Heidelberg, May 24, 1973
E / Pt-Ka / Pr E-287 09851/0502