DE1914114A1 - Anti-lock control system with two-stage pressure reduction - Google Patents

Description

Anti-lock control system with two-stage pressure reduction The invention relates to an anti-lock control system for pressure medium-actuated vehicle brakes a valve device in which, inter alia. two specific operating states are possible, in which the brake pressure according to different pressure% time functions, e.g. fast and slowly, descending, and with a signal transmitter containing a wheel sensor, which among other things can emit an acceleration signal and two deceleration signals, namely a first deceleration signal that occurs as long as the rotation deceleration value of the the wheel to be braked is greater than a lower limit value, and a second deceleration signal, this occurs as long as the rotation deceleration value is greater than an upper limit value.

Such a system is from the German Auslegeschrift 1166 012 (same content with U.S. Patent 3,017,145). With this system, the operating status goes along with it faster pressure reduction, which is initiated by the second delay signal, im further Braking process always takes place immediately in an operating state with a pressure increase above. However, it has been found that such abrupt changes in the pressure movement should be avoided as far as possible if one is aiming for gentle changes in the rotational speed of the wheel. And this is the goal of further developments in this area: you want wheel speed diagrams achieve that with the smallest possible amplitude fluctuations around the braking-favorable Winding wheel speed curve, and in its shape a sine line close to con. In view of this, it is desirable between the phase of rapid pressure reduction and a subsequent increase in pressure to switch on a phase of slow pressure reduction.

The invention makes use of this basic concept from an earlier proposal according to patent application P 16 55 432.8, according to which a bistable Switching device is provided, which when a rotational delay occurs The wheel tilts into a switching state that causes the pressure to drop and only when a certain rotational acceleration occurs in the normal switching state tilts back. Such a bistable switching device should be the one to be switched on again Timing the phase of slow pressure reduction.

The proposal according to the invention is therefore that a bistable Switching device provided with a working position and a normal position which is connected to the valve device in such a way that its working position assigned to the operating state of the valve device with slow pressure reduction is, and that the bistable switching device on the other hand at the signal generator in such a way is connected that the second Delay signal them into the Working position and the acceleration signal tilts them into the normal position.

Such an extension can only be achieved with a large rotational deceleration initiate the operating state with slow pressure drop, while with low Rotation decelerations the same operating state only lasts as long as the first deceleration signal self.

The advantage results from a consideration of the assessment principles for the response delay of the delay signals.

Signal generators of the type under consideration here give their delay signals does not depend on the exact point in time in the mathematical sense. to which the rotation delay a certain limit value in terms of the differential quotient of the rotational speed exceeds, but only when a further condition is met, according to which since If the rotation delay limit value is exceeded, the rotation speed is increased by one certain amount gSv must have changed. We refer to a more detailed explanation these considerations on our German patent application P 16 55 454.4. Purpose of this Another condition is certain interfering influences, i.e. short-term, but otherwise Harmless changes in rotational speed, e.g. road bumps or wheel vibrations with other reasons to stay away from the control system. On the other hand, however, the system as sensitive as possible, which is tantamount to striving to to achieve a possible uniform and sinusoidal wheel speed diagram, shouldv be as small as possible. So far the lower limit was determined by the fact that after each pressure drop, a high enough spin had to occur was to generate an acceleration signal and the bistable switching device to tilt. This limit was around Av = 7 km / h.

If #v had been made smaller, then a corresponding Rotation delay can initiate a pressure drop that can no longer be stopped. Security considerations, those that start at this point should not be pursued further here. It should only become clear that there is a by the bistable switching device after earlier suggestion gives conditional lower grams for #v.

In a system with two delay signals and two operating states With slow and fast pressure reduction, the invention now makes it possible for everyone Assign a signal to its own #v. The second, due to a strong delay in turning The signal called up to now has received a #v of about 7 km / h and the first, from A signal caused by a lower delay can be significantly lower #v, for example from about 3.5 km / h. The system then recognizes you beginning blocking process earlier than before and also smaller turning delays are wicksam regulated. On the other hand, the system is insensitive to short-term strong rotation delays, as this only causes a rapid pressure drop cause when the rotational speed changes by a larger value Has.

The embodiment shows in detail that according to the invention The duration of the operating state with a slight pressure drop is then not of a bistable type Switching device depends when only a first delay signal has occurred and this was not preceded by a second delay signal @@. In this case it ends the operating state with the increase of the first delay signal, however, closes then a phase of a further operating state with constant pressure, the is controlled by a timer with a fixed Voreins @ @@@@.

In the following it is explained with which valve devices can implement a system according to the invention. Valve devices for pressure reduction two slopes are known per se, e.g. from the German mentioned in the introduction Universal script. There it is also possible to apply the pressure with two slopes to increase. In a further development of the invention, as mentioned above, in addition to A fifth of these known four operating states can be provided during this the pressure is kept constant. A valve device capable of this can be made up of four open-close valves, for example. two of which in parallel switched on between the pressure source and the edge brake cylinder and opened normally Are parallel while two more between the wheel brake cylinder and an outlet turned on and normally closed. Preferably one of the two Valves lying in parallel are throttled, i.e. with an upstream flow throttling point or designed with a smaller flow cross-section.

Another way of realizing such a valve device results from the use of open-close valves on the one hand and two-cross-section valves on the other hand, which latter is wide in one position and wide in the other Position have a narrow flow cross-section. One two-cross-section valve each and an on-off valve are placed in series and in the inlet line as well placed in the outlet pipe, with the on-off valve in the inlet pipe normal open and the corresponding valve in the outlet line is normally closed.

However, the invention is not only suitable for anti-lock control systems, in which the combustion pressure is changed by valves becomes that immediate are arranged in the hydraulic lines of the brake system, it is suitable rather also for systems with indirect pressure control. An example of a US Pat. No. 3 gives such a system with a corresponding valve device 301,608. There is a liquid cylinder directly with the wheel brake cylinder in connection, the piston of which is movable with another in an air cylinder Piston interacts and by a strong spring in the end position with the smallest possible Content of the liquid cylinder is pushed. The other piston, by the way could also be replaced by a rolling membrane, divides the air twister into one Air chamber and a vacuum chamber with vacuum connection. When the air chamber is opened the pistons move against the spring force and lower the brake pressure.

According to the invention it is proposed here that the air chamber is parallel is connected to the outside air via two normally closed valves. Will one If these valves are opened, the pressure drops slowly, if both are opened, the pressure drops he off faster. The operating state "hold pressure" results when both valves are closed. A very slow increase in pressure is also attributable to this condition, which results in some known valve devices in that in the Air piston is a fine nozzle which connects the air and vacuum chambers to one another connects For the operating state "slow pressure increase" according to the previous Definitive a special connection line is proposed between the air and vacuum chambers. In the "hold pressure" operating state, this connecting line is normally quiet open valve closed. The operating state "rapid pressure increase" results Finally, if there is one in the main pressure line in front of the liquid cylinder Lying inlet valve opens.

According to another further development of the establishment, a system with direct pressure control and five operating states with only three valves be trained. It is suggested, in addition to a normally open one, with the Pressure source connected open-close valve and a normally closed, with the outlet connected open-close valve between the connection of these two valves with each other and to arrange a two-cross-section valve on the brake cylinder. This then effects the greater or lesser steepness of both the pressure build-up and the pressure drop. Optionally, instead of the two-cross-section valve here and in the previous examples an on-off valve with a flow resistance connected in parallel is also used will.

In the following an embodiment of the anti-lock control system, which can optionally be used for various valve devices, together with these are explained in detail.

Fig. 1 shows the logic block diagram of the system, Fig. 2 shows a graphical representation of wheel speed, d @ brake pressure and electrical Pulse of the Blockssbaltbildes, Fig. 3 is a first valve device with four Open-close valves Fig. 4 shows a second valve device with two open-close and two two-cross-section valves, Fig. 5 is a valve device for indirect pressure @@@ flow, Fig. 6 is another valve device with only three valves for direct pressure control, also two electrical symbols explaining the block diagram of FIG. 1 are entered, Fig. 7 shows a correspondingly modified timing diagram, and Fig-. 8 shows a further development of the block diagram according to FIG. 1.

First of all, FIG. 1 is described together with FIG the identically designated terminals in the two figures are connected to one another must think. A signal transmitter 1 is indicated schematically on the left. It has three exits which are normally at ground potential, but at times have a positive potential, i.e. signal potential. The outputs and their corresponding signals are marked with -b1, + b and -b2 bc. -b1 is the first delay signal that occurs as long as the rotational deceleration value of the wheel is greater than a lower limit value. -b2 is the second delay signal that always occurs together with -b1 when the rotation deceleration value is greater than an upper limit value.

+ b is the acceleration signal that occurs when the spin exceeded a lower limit, but not yet exceeded an upper limit Has. If the upper acceleration limit is also exceeded. then disappears this acceleration signal again. With reference to Fig. 2 will be referred to later on Temporal relationship of the three signals to one another and to the speed of rotation of the wheel.

In FIG. 1 there is also an oil pressure switch 2 and a brake light 3 indicated. This switch closes right at the beginning of a braking process, if the brake pressure exceeds a few atmospheres, e.g. three or four atmospheres.

At connection point 4 of the brake light and switch is open Switch positive potential and ground potential when the switch is closed. the Circuit has four outputs e1, e2, a1 and a2. These are shown in Fig. 3 with in the hydraulic Pressure line system lying solenoid valves connected, correspondingly with large Letters are designated. The pressure cylinder, not shown, is on the pipeline 5 of the brake system or the other controlled pressure source is connected at 5 the wheel brake cylinder and at 7 an outlet line, possibly a return pump, connected. Between 5 and 6 are the two inlet valves E1 and E2, between 6 and 7 the two outlet valves A1 and A2, each in a parallel arrangement. With a flow restrictor 8 or 9 is connected in series to one of the two pairs of valves.

The block diagram contains a flip-flop 10, which here is the bistable Switching device embodied according to the invention.

It has two entrances on the left and two exits on the right. The signals on the two outputs are always opposite to each other. So if that denoted by k The signal at the lower output is "O", then the signal at the upper output is "1".

This is the normal position of the flip-flop. In the working position the two output signals are reversed. The b output of the signal generator is with the upper input and the -b-tusgang with the lower input of the flip-flop 10 tied together. A branch of the 42 output also leads to terminal a2. The exit of the flip-flop 10 is connected to one input of an OR gate 11 while the second input of this OR gate is at the -b1- output of the signal generator.

The -b1 line also leads to the input of an AND gate 12, whose second input is connected to the upper output of the Zlip-Flop 1 (. The output of the AND element is with a Monoflop 13 connected to its Output the signal m occurs. It is fed to an OR-member 14. The exit this OR gate, equipped with three inputs, leads to terminal e1. Again Arrow in the nonoflop symbol indicates 1, the signal m is normally "O". Only if If an impulse occurs at the input of the monoflop, the monoflop flips over, so that then the signal m becomes "1". After a certain holding time, the monoflop falls back. If a signal of a longer duration is present at the input of the monoflop, the monoflop tips over also and cannot fall back sooner than the input signal disappears. In particular, the monoflop is designed in such a way that the continuation of the signal m after the disappearance of the input signal on the monoflop always the same and thus is independent of the duration of the input signal.

The other two inputs of the AND gate 14 are connected to the output of the signal generator and connected to terminal a1.

Finally a second flip-flop 15 is also provided has two inputs, but only one output connected to the output terminal e2. In the normal position of this flip-flop, the output signal is "O", this position occurs as long as there is no braking or is only braked so hard that the anti-lock control system does not come into operation. The upper input of the flip-flop is connected to terminal 4 connected between the brake light 3 and the associated contact 2, while the lower The input is at the -b1 output of the signal generator.

First of all, the method of operation known per se will be described with reference to FIG of the signal generator 1 explained. The diagram at the top shows how the speed is VF of the vehicle to be braked decreases slowly but steadily.

The peripheral speed vR of a vehicle wheel is plotted below this. As long as there is no braking (all the way to the left), the wheel circumferential speed is the same the vehicle speed. The recorded one then results during the braking process Wheel speed curve, during which the wheel speed is always lower than the vehicle speed. The wheel speed curve is ultimately that t result of the pressure influence brought about by the anti-lock control system. First but just accept the curve.

It should only be made clear that on the signal transmitter in the first signals entered in three lines of the signal diagram occur. As long as the wheel speed drops, and the slope does not exceed a certain level, the signal occurs -b1 on. This is the case immediately at the beginning of the braking process, then it recovers the bike speed again and then a very steep descent follows. During this If the vehicle drops steeply, a second limit of the wheel deceleration is exceeded for a short time and this creates the signal -b2. In order for the signal + b to arise, the wheel speed must Achieve a certain steepness during the acceleration times.

This is not the case in the first half of the chart, however when rising again in the second half. It is now a specialty of here described signal generator that according to an earlier proposal, the signal + b also then becomes "O" again when the wheel speed increase is particularly steep. It So there are two single + b-pulses in the diagram, for as long as it is the steepness of the increase in wheel speed assumes average values.

The description of the mode of operation of the overall system is now given under Addition of the brake pressure P and the other recorded signals. The signals at the output terminals of the logical system in connection with the respective chosen Valve device, initially that of FIG. 3, the valve positions again and thus also the pressure movement tendency. Since the inlet valves E1 and E2 are normal are open, signal "O" at terminals e1 and e2 means "valve open" and that Signal "1" at these terminals means "valve closed. The opposite applies to the Outlet valves A1 and A2.

Signal "1" at terminals a1 and a2 means "valve open" here.

The flip-flops and the monoflop are at the beginning of the braking process of the logical system in the normal position. All signals are "0". The first Brake pressure P controlled by the driver alone rises steeply because both inlet valves open and both exhaust valves are closed. Even with a very small one Brake pressure closes the oil pressure switch 2, that is, at a point in time that is still outside of the diagram. Now the brake light lights up, the change in potential at terminal 4, however, has no effect on the logic system, since the flip-flop 15 is in its normal position anyway.

The first appearance of the -b1 signal has three effects Flip-flop 15 toggles and generates the signal e2. About the AND gate 12, at its second If a signal is applied to the input from the flip-flop 10, the monoflop 13 is triggered. It generates the signal mund this via the OR gate 14, the signal e1. Finally the signal a1 is generated via the OR gate 11. The output signals mentioned cause both inlet valves to close and the throttled one to open Exhaust valve A1. As a result, the pressure will slowly decrease. As a result of this pressure drop the wheel catches down and the signal -b1 ends. Hence a, that ends as well The exhaust valve closes and the pressure in the wheel brake cylinder is kept constant, since the line 6 to the wheel brake cylinder is closed on all sides.

With the disappearance of -b1, the holding time T of the monoflop begins 13, which is entered in the diagram by a double arrow. After this Time the monoflop falls back, and with m also e1 ends, so that now the throttled Inlet valve E1 opens. The pressure increases slowly.

One must now imagine that the wheel is on a slippery spot the road becomes slow and for this reason the wheel speed is initially slow and then it decreases faster and faster. Also now the signal -b1 appears with the corresponding and consequences already explained. The slow pressure reduction is not enough, however to stop falling wheel speed. There is a risk of the wheel locking. That Signal -b2, which now appears, therefore causes signal a2 and opens that unthrottled exhaust valve A2. The pressure is therefore now falling rapidly. Simultaneously however, the flip-flop 10 according to the invention is also tilted into the working position.

a1 is now additionally. caused by k, while the AND-Giied 12 blocks and thus the hold time of the monoflop 13 begins.

The rapid drop in pressure causes the wheel to quickly recover catches and -b2 soon disappears. This also closes the second exhaust valve AS, however, the flip-flop 10 does not yet flip back into the normal position. That throttled The outlet valve is still open, as I said, as a result of the signal -b1 on the one hand and independently as a consequence of the signal k on the other hand. In the further course ends the hold time T and thus the signal m, but this has no effect, since the Signal e1 as a result of the line connection between terminal a1 via the OR gate 14 is maintained with terminal e1. Without this connection, in this intermediate stable, in which neither an acceleration nor a deceleration signal there is 1 pressure again increase. But as it is, the pressure falls further slowly, until the appearance of the + b signal. This is the deciding factor the end idea of the present invention. While at the beginning of the braking process as no -b2 signal had yet preceded, the slow pressure reduction together with ended with the -b1 signal, it only ends when + b appears.

The + signal now takes over the further locking of the inlet valve E1 and tilts the flip-flop 10 back into the normal position. This disappears on and the exhaust valve closes, while on the other hand the AND gate 12 prepares will let future -b1 signals to monoflop 13 through. The pressure remains for the time being constant until the + b signal disappears, which is what happens here first, because the wheel speed increases particularly steeply. This is due to an increase in pressure encountered as a result of opening the throttled inlet valve E1. As well as the wheel speed curve becomes flatter again, E1 closes again, so the system waits for further developments away. But there is no further steep increase because the aircraft speed has already been largely achieved. Thus, the second + b pulse ends as a result of falling below of the lower acceleration limit value, which is the desired three-movement state of the wheel is reached and the control cycle has ended. The pressure is increasing now continues and will subsequently lead to another rule cycle.

After the braking process has ended, i.e. when the driver shuts his foot off the brake takes, and the brake pressure goes back to its minimum operating value, The oil pressure switch 2 also opens, which then sends a signal to the upper input of the flip-flop 15 arrives and this also tilts back into the normal position.

At this moment, which is no longer shown in the diagram, the initial state of the overall system is then reached again. The one on the left in the diagram The steep rise in pressure shown only occurs once at the beginning of a braking process on. This is the conditions at the beginning of a firing process, where only once a relatively large volume of pressure medium must flow into the wheel brake cylinder, around the sealing sleeves and the supply hoses switched on in the system to stretch, best suited.

FIG. 4 shows an alternative to the valve device according to FIG. 3 with the difference, however, that only two really tightly closing valves E1 and A1 are required. The two cross section valves shown are E2 and A2 in a sense only adjustable flow restrictors. As with E2, they exist referred to, from a cylinder 16 with two opposite line connections and a piston 17 movable in the cylinder with a circumferential groove 18 very rubbed Cross-section. The piston is connected to a magnet armature 19 via a piston rod, which is attracted by a coil 20. The line connections are located at E2 on the left side of the cylinder, so that when the winding is de-energized, the piston 17, which is held in its right end position by a spring 21, the free one Flow between the two line connections is not obstructed. When the coil 20 However, is excited, the piston is on the left and now throttles its circumferential groove the flow area. In the case of valve A2 'they are. Line connections on the right Half of the cylinder is attached and accordingly the flow is not here excited winding (normal position) throttled. Same signal combinations on the Clamps e1, e2, a1 and a2 therefore cause the same pressure movements as in Figure 2 are shown.

The same is done with the help of indirect pressure influence according to Fig. 5 reached. Here is between a performance 22 for liquid pressure medium, which with connected to the master pressure cylinder or another pressure source controlled by the driver is, and a line 23, which leads to the wheel brake cylinder, a normally open Inlet valve E2 switched on. There is also a fluid cylinder with the wheel brake cylinder 24 in connection, in which a liquid piston 25 moves.

This is larger than a piston rod with an air piston 26 Connected diameter, which bee in an air cylinder. He shares this air cylinder into an air chamber 27 and a vacuum chamber 28 with a vacuum connection 29.

A spring 30 pushes the double piston thus formed to the left in the position in which the cylinder of liquid has its smallest content. The air chamber 27 stands above two normally closed valves, namely A'1 and A2 ', which are referred to here as Air valves are formed, and through two filters 34 with the atmospheric air in connection. The two valves are parallel to each other and the first valve A1 '' is also equipped with a throttle 2. Finally in a bypass line which connects the air chamber 27 with the vacuum chamber 28 at the ends of the cylinder, a normally open air valve E1 '' is switched on.

The device according to FIG. 5 acts as follows: In the first operating state the brake pressure is built up very quickly in a direct way, namely when the inlet valve E2 is open. However, this valve is closed during a control process. It can therefore also be replaced by a ball valve in a manner known per se, which is pushed open by the liquid piston 25 in its extreme left position wfrd uri is always closed when this piston is not in its extreme position left position.

The spring 30 is dimensioned so strongly that the double piston also remains in the left position when the greatest brake pressure occurs, provided that on Air piston there is no pressure difference. The operating state with slow pressure reduction also requires signals e1 and a1. e1 closes valve E1 "so that sets Air and vacuum chambers are separated from each other. A small passage opening 33 in flask will be mentioned later. The signal a1 opens the throttled air valve As air flows into chamber 27, the double piston moves To the right. This increases the capacity of the liquid cylinder 24 and the brake pressure decreases accordingly. If A'2 is also opened, then flows more air into the chamber 27 and the pressure reduction is correspondingly faster themselves. This is the third operating state. The fourth operating state "slower Pressure rise "occurs when both valves A" and Å'2 are closed, the valve E1 "is however open. Now the pressure difference between air chambers and balance the vacuum chamber, so that now the spring 30 moves the double piston to the left shifts and thus increases the pressure. The fifth operating state "hold pressure" results if the fine bore 33 in the air piston is missing and all valves are closed are. The air piston can be in all intermediate positions in this situation stay.

However, it will result from leaks that cannot be completely avoided adjust a very slow movement anyway.

In order to create defined relationships here, it is recommended how known per se to provide the bore 33, so that also1 when all valves are closed the piston moves extremely slowly to the left and the pressure corresponds to increases. The bore can easily be dimensioned in such a way that the pressure increase is still much slower than the slow pressure increase according to the pressure diagram of Fig. 2.

You can then easily hold this operational status as "pressure" describe. This valve device is also electrically connected to the logic system Fig. 1 connected and works as described there.

Finally, FIG. 6 shows a fourth exemplary embodiment of a valve device shown, which has only three valves and therefore not easily connected to the four Terminals of the logic system according to Fig. 1 can be connected. Fig. 6 contains hence a small extension of the logical system that makes such a connection enables.

The valves E1 in the inlet line and A1 in the outlet line correspond the valves according to Fig. 3 and 4. They are also as there to the terminals e1 and a1 connected. The third valve Z is normally open and is in the direction of the Rodbrcas cylinder leading line. A flow throttle is arranged parallel to Z. How nice this valve and its parallel throttle could also be mentioned by a two-cross-section valve like food to be replaced. The terminal a2 is shown in FIG. 6 with the input of an inverter 34 connected, the output of which is connected to an input of an AND gate 35. At the other The input of the AND element is connected to terminal e2 and the output that connects the Signal z leads, controls valve Z.

The five operating states of this valve device are as follows: When Z is closed, the pressure becomes slow depending on the position of E1 and A1 rise or fall slowly. If Z is open, the pressure is correspondingly fast rise or fall rapidly. When both valves E1 and A1 are closed, so the pressure remains constant, regardless of whether Z is open or closed is.

Fig. 7 shows the signal z as it results from e2 and a2, where e2 and a2 from Fig. 2 are simply taken over. If e2 and a2 are at "O", then z also to "O". If only e2 is on "1", then z is also on "1" because the AND element 35 has a signal at both inputs. If, on the other hand, e2 and a2 are 1, then z goes again back to "O". This is during the -b2 signal during the strong rotation deceleration the case. So Z opens and the pressure can drop steeply. Overall, therefore also achieved with the valve device according to FIG. 6, the same pressure curve as it is drawn in FIG.

After the anti-lock control system according to the invention using the example of Figure 1 and various valve devices is explained below some further developments of the invention shown in FIG. 8 will be discussed.

In order to understand these further training courses, one blacks out the processes during the Braking, i.e. when the pressure rises for the first time before the anti-lock braking system takes effect, visualize. The brake pressure should be built up quickly and unhindered, therefore it must be ensured that initially both inlet valves E1 and E2 remain open. However, there is a risk that this first pressure increase will be caused by -b1- or + b-signal that is affected by an uneven road surface or by a start changing Could be caused by the friction coefficient of the roadway. The + b signals can be particularly easy occur, because their response threshold is kept particularly low. As before but described + b-Sigral cause a closing of the inlet valve E1 and thus at least one prevention of the initial pressure increase. It is therefore suggested that an AND gate 39 (gate) in the + b-channel between the signal transmitter 1 and turn on the OR gate 44, d with its second input at the output of the flip-flop 15 is connected. In Figure 8, this additional AND gate 39 is next to one further AND element 38 and a time delay element §7 permanently entered.

Otherwise, FIG. 8 is identical to FIG. 1.

So as long as the flip-flop 15 is in its normal position, a possible + b signal cannot to the OR gate 14 and thus to the inlet valve Penetrate E1. Rather, this is only possible when a -b1 signal has occurred is and the flip-flop 15 has tilted into its working position.

But since a -b1 signal also occurs during braking can not help much. The first -b1 signal flips the flip-flop 15 and thus closes the inlet valve E2, which usually has the larger cross-section.

It is therefore also proposed to add a time delay element 37 to the flip-flop 15 upstream. Only when the input signal of this time delay element is one of this Member has lasted its own delay time appears; an output signal. A -b1 signal can therefore only be effective on flip-flop 15 if there is a Holds for a delay.

To finally also an undesired closing of the inlet valve To prevent E1 as a result of a -b1 signal on the way via the monoflop 13, should yet another AND gate 38 switched between the monoflop and the OR gate 14 will. Its second input is just like that of the AND gate 39 at the output of the flip-flop 15 to connect.

It sure does not cause any difficulty, the lag time of the link 37 to be dimensioned in such a way that all interfering signals are filtered out with certainty and thus all obstructions to the pressure increase when braking are avoided.

- Claims -.

Claims (13)

P a t e n t a n s p r ü c h e 1) Anti-lock control system for pressure medium-actuated vehicle brakes with a valve device in which and target certain operating states are possible are; in which the brake pressure is determined by different pressure-time functions, e.g. fast and slow, descends, and with one containing a wheel sensor Signal generator, which includes an acceleration signal and two deceleration signals can emit, namely a first deceleration signal that occurs as long as the rotation deceleration value of the wheel to be braked is greater than a lower limit value, and a second deceleration signal ^ .l, this occurs as long as the rotation deceleration value is greater than an upper limit value, characterized in that a bistable holding device (10) with a working position and a normal position is provided which is connected to the valve device in this way is that its working position corresponds to the operating state of the valve device (E1, E2? A1, A2) is assigned with slow pressure reduction, and that the bistable switching device on the other hand is connected to the signal generator (1) in such a way that the second delay signal (-b2) it in the working position and the acceleration signal (+ b) it in the normal position tilts. 2) anti-lock lever system according to claim 1, characterized in that that a timer (13) is connected to the signal transmitter and the valve device, which is triggered by the first delay signal (-b) and the valve device Holds for a certain period of time in a further operating position in which the Brake pressure does not change. 3) anti-skid control system according to claim 1 and 2, characterized in that that a switching connection (12) between the bistable switching device (10) and the timer (13) is provided, which causes that during the working position of the bistable switching device, the timer cannot be triggered. 4) anti-lock control system according to claim 1 - 3, characterized by a second bistable switching device (15), which of one when opening the brake light switch (2) generated signal in their normal position and from the first delay signal (-b1) is tilted into its working position. 5) anti-lock control system according to claim 1 - 4, characterized gekennzeiclmet, that the signal generator (1) is connected to the valve device via a gate circuit (39) is in such a way that the acceleration signal (+ b) that operating position one, yours, in which the brake pressure does not change, and that the gate switch on the second bistable switching device is connected and in its normal position locks. 6) anti-lock control system according to claim 1 to 4, characterized in that that the second bistable switching device (15) is preceded by a time delay element (37) is which the first delay signal to the bistable switching device only can be evaluated effectively after this signal has lasted a certain delay time Has. 7) anti-lock control system according to claim 1 to 4, characterized in that that the timing element (13) is followed by a gate circuit (38)}, which also is connected to the second bistable switching device and in its normal position locks. 8) anti-lock control system according to claim 1, characterized by a valve device consisting of four open-close valves, two of which (E1, E2) switched on in parallel between the pressure source and the wheel brake cylinder and are normally open, while two more (A1., A2) between the R3dbremsylinders and an outlet are switched on in parallel and normally closed. 9) anti-lock control system according to claim 1, characterized by a valve device with two open-close valves and two two-cross-section valves, which latter one broadens in one position and one in the other result in a narrow flow cross-section, with a normally open on-off valve (21) and a two-cross section valve (E2 ') between the pressure source and the wheel brake cylinder as well as a normally closed open-close valve <A1) and a two-cross-section valve (A2,) are connected in series between the wheel brake cylinder and an outlet. 10) anti-lock control system according to claim 1, characterized in that that a liquid cylinder (24) is directly connected to the wheel cylinder whose piston is connected to a further piston that can be moved in an air cylinder (26) cooperates and by a strong spring (30) in the end position with the smallest possible Contents of the liquid cylinder is urged that further the further piston the Air cylinder in an air chamber (27) and a vacuum chamber (28) with a vacuum connection (29) divides, so that when the air chamber is opened, the pistons move and the brake pressure is increased lower and that the air chamber is parallel via two normally closed valves (A1, A'2) is connected to the outside air. 11) anti-lock control system according to claim 6, characterized in that that the Zuftammer is connected to the vacuum chamber via a normally open valve (E'1) is. 12) anti-lock control system according to claim 1, characterized in that that a valve device is provided, consisting of a normally open, open-close valve (E1) connected to the pressure source, a normally closed, with an outlet connected on-off valve (A1) and one with the wheel brake cylinder connected two-cross-section valve, with the second connections of all three valves are connected to each other. 13) anti-lock control system according to claim 5 and 7, characterized in that that on-off valves (Z) with flow resistors (36) connected in parallel instead the dual cross-section valves are used.