DE2742991C2 - Electronic anti-lock control system for wheeled vehicles - Google Patents

Description

An anti-lock control system according to the generic term of claim 1 is for example known from US-PS 39 53 080.

This control system enables adaptation to different driving conditions due to changing

Licher coefficients of friction of the roadway being traveled on and different road loads.

A brake air signal is generated in a control channel, "vnn the wheel deceleration a predetermined Exceeds threshold. A second tax channel! leads a from the difference between measured wheel speed and the estimated vehicle speed. For this, the wheel deceleration compared with an assumed vehicle deceleration and the difference in an integrator

integrated. The estimated vehicle deceleration is also determined in part by the increase in idle speed, while the brake is released. The second control channel also includes an accelerator switch, which clears the error sign to put the brakes back on

b5 to be applied when a predetermined wheel acceleration is exceeded. At the end of a control process the integrator is reset to zero under all braking conditions. Furthermore, the changeable component

component from the wheel acceleration during the entire control process, i.e. also when the brake is applied available.

The invention is based on the object, proceeding from the known Blockicrschutz-Stcucranlagc, the The adaptability of such continues to improve.

This object is achieved by the features set out in the characterizing part of claim 1.

Further advantageous refinements of the invention emerge from the subclaims.

The design according to the invention enables the control system to work optionally in three different modes of operation, with the duration of the brake release being controlled solely by the delay switch in a first mode of operation, which results in optimal braking behavior for a heavily loaded vehicle and / or a high coefficient of friction on the roadway. 1t * n J »roriHt

In the second mode of operation, the braking duration, which is determined by the delay switch, is through increases the influence of the brake cycle depth integrator, which means optimal braking conditions for medium vehicle loads and medium friction coefficients of the roadway be created.

Finally, in the third mode of operation, the braking duration is controlled by the brake release lock switch, whereby the control system for braking conditions with low vehicle load and / or low Coefficient of friction of the road works favorably. With a weak application of the brakes on a roadway low coefficient of friction, the actual wheel deceleration can be the value of the maximum vehicle deceleration, represented by the delay reference signal. If this exceeding is retained, so the braking cycle depth signal is continuously set to a progressively higher value until it reaches a value reached, in which the brakes are released so that the wheel at risk of locking can catch up with speed.

The test circuits provided enable the control system to be switched off if errors occur, whereby the control circuits are prevented from releasing the driving brakes if there is no brake release signal or if the brake release signal persists for longer than a specified time.

The invention is explained with reference to the drawings

1 is a block diagram of a preferred embodiment of an anti-lock control system according to the invention,

Fig.2a and 2L put together a schematic Circuit diagram of the control system according to FIG. 1 and

F i g. 3a, 3b, 3c and 3d diagrams, the three possible Modes of operation of the control system according to FIGS. 1 and 2 explain.

The following description is a preferred embodiment of a control system for heavy towing vehicles with air brakes. However, the invention is general to all types of wheeled vehicles with any Brake systems applicable.

In the preferred embodiment it is provided that each vehicle axle is independent of the others Axles is monitored, whereby both the axles of the tractor and the trailer are monitored so that each axle is equipped with a complete anti-lock control system. The only thing the brake systems of the various axles have in common is an arbitrarily actuatable air pressure source. which supplies the braking systems. The control of all brakes of tandem axles could be modified Way can be monitored by a single anti-lock control system, as well as other desired ones Combinations can be used.

The control system is based on the well-known principle of sensing a risk of blocking when the vehicle is in use Braking, lowering the brake pressure for a specified time and then increasing the

ίο brake pressure, with such braking cycles if necessary repeated several times. The term "brake cycle depth" used in the description below represents the size of the discrepancy between the wheel speed and the wheel speed during a brake release process at the beginning of the brake release.

As FIG. I shows, the wheels 10 and 12 of an axle located on opposite sides of the vehicle are assigned speed sensors 14 and 16, respectively. These are νθΓΖί! ^η £ ^ω0 ί ^{εΑ Q} ' ^c a! * »1 / Ir / MTiQCTn /» ticphp \ VnnHli * r designed with variable reluctance and toothed wheels that supply alternating current signals, the frequency of which is proportional to the wheel speeds. These signals are fed to square-wave amplifiers 18 and 20, respectively, which form square-wave signals, the frequency of which is the same as the frequency of the alternating current signals. The square-wave signals of the square-wave amplifiers 18 and 20 are fed to associated tachometer generator circuits 22 and 24, respectively, which supply electrical analog signals, the magnitude of which is proportional to the speed of the wheels 10 and 12, respectively. These analog signals are fed to a speed selector 26, which feeds the analog signal representing the lower wheel speed to a conductor 28.

The wheel speed signal is transmitted via conductor 28 to a delay switch 30, a brake cycle depth integrator

grator 32, a deceleration amplifier 34, an acceleration switch 36, a brake release lock switch 38 and the negative inlet of a brake cycle depth comparator 40 forwarded.

The brake cycle depth comparator 40 delivers a brake release signal when the size of the signals at its positive inlet exceeds the magnitude of the signals appearing at the negative inlet. The brake release signal is fed to a shutdown circuit 42 which energizes a brake release magnet 44, so that a release of the Brake takes place while a brake release signal is present.

The deceleration switch 30 provides a control signal when the wheel deceleration is a reference deceleration which indicates a risk of blocking The reference delay is roughly equal to the maximum possible vehicle deceleration and is based on the number of wheels addicted. In the exemplary embodiment it is assumed that the reference delay, which indicates a risk of blocking, at a wheel speed of zero 03 g and at a wheel speed corresponding to 96 km / h is 13 g. The delay switch 30 terminates the control signal when the deviation the wheel speed from the integral of the reference speed during the brake fan becomes zero The control signal is fed to the positive inlet of the brake cycle depth comparator 40

The brake cycle depth integrator 32 provides a brake cycle depth signal to the positive inlet of the Brake cycle depth comparator 40. This signal is a composite signal with a first part.

which shows the amount by which the time integral of the Deceleration reference signal exceeds the wheel speed while the brake is being applied and a second Part that is the integral of the wheel acceleration during

7 8

of the brake fan «. The delay reference signal for switched! and supplies a brake release lock signal to the

the braking cycle depth integrator 32 is approximately the negative inlet of the braking cycle depth comparator 40.

train delay of the delay shutter 30 equal. The brake release lock signal is activated by a control signal

so that the braking cycle depth signal of the braking cycle depth supplied by the delay switch 30 is cleared

fenintegrators 32 essentially the size of the turning 5 or when sensing an acceleration that is greater

represents change in number during the brake fan. In ßer is a given lower acceleration

Embodiment is assumed that this level, which is a function of the size of the braking cycle

Zugsverziiiii ₆ 1.0 gist. depends on the signal. In the exemplary embodiment

The brake release signal of the brake cycle depth, the brake release lock signal of the brake release lock disappears 40 clears the reference delay in braking cycle switch 38 upon sensing an acceleration of depth integrator 32 as long as it is available. If the 0.5 g ends when the braking cycle depth signal is zero Brake air signal of the brake cycle depth comparator 40, and at 0.1 g for the largest brake cycle depth signal. at to cause the brake to be reapplied, there is no control signal and the wheel is accelerated sets the braking cycle depth signal to a value that is less than the specified lower acceleration, which corresponds to the amount by which the timing level falls, the brake release lock signal occurs on After the reference delay, turn the wheel speed up again using the brake release lock switch. increases during the time in which the brake is applied and the size of the brake release lock signal is released by the brake release was. If the mean wheel deceleration is less, the lock switch 38 is greater than the maximum value of the as the reference delay, the braking cycle signal is used by the braking cycle signal set to zero. Is the mean value of the 20 grator 32. There can thus be a brake release signal at the outlet The wheel deceleration is greater than the reference deceleration, as determined by the brake cycle depth comparator 40 by the controller the braking cycle depth signal to a corresponding signal of the delay switch 30 only occur, set the appropriate value as described above. if the wheel deceleration is the reference deceleration of the

The delay amplifier 34 supplies a braking cycle delay switch 30 which exceeds the blocking

Klustiefenverbindssignai, the size of the delay 25 indicates danger. Furthermore, the size of the control signal

is proportional until it is greater than the largest at a predetermined delay from the delay switch 30

is saturated, which is lower than the braking cycle depth reference signal at the braking cycle depth

delay reference signal of the delay switch 30. comparator 40, so that the control signal at any time

In the exemplary embodiment, the deceleration booster delivers the brake release signal and thus during its best-

34 saturated when the wheel deceleration causes the brake to be released approx. 0.8 g too soon, is enough, the delay amplifier 34 is designed in such a way- After the brake is released by the control

det that the control signal of the delay switch 30 is triggered gnal, the response of the control changes

always returns to the low value before the plant as a function of the length and depth of the

Output of the deceleration amplifier 34 on the low braking cycle indicated by the braking cycle depth signal

toggles the value. This ensures that the braking cycle 35 from the braking cycle depth integrator 32, the deceleration

depth reference signal of the deceleration amplifier 34 of the vehicle and the acceleration of the vehicle wheels

long cf lasts as the control signal of the delay that is displayed.

switch 30. The braking cycle depth reference signal of the With heavy load on the vehicle and / or high

Deceleration booster 34 goes into an inlet of a hen coefficient of friction of the roadway, in which the brake cycle

Grid 46 a. 40 is short and shallow, the control

The acceleration switch 36 supplies a braking system solely through the deceleration switch 30. At

Cliff depth reference signal when sensing a given operating mode causes the control system to go out

nen upper level of a wheel acceleration. In the output of the delay switch 30 a reapplication,

The acceleration switch 36 of the brake provides an exemplary embodiment. This mode of operation is favorable

this braking cycle depth reference signal in the case of a wheel condition 45 is a prerequisite for this driving condition, acceleration of about 2.0 g. The outlet of the accelerator With average coefficient of friction of the roadway and / or

inclination switch 36 is a second inlet of the grille- average load on the vehicle is the braking cycle-

ters 46 fed, the outlet of which is deeper into the negative inlet. The duration of the brake release signal is shown in

of the braking cycle depth comparator 40 is received. in this case from the brake cycle depth signal from

The grid 46 connects the larger braking cycle 50 braking cycle depth integrator 32 in conjunction with the

brake cycle reference signal of the delay amplifier 34 brake cycle reference signal at the negative inlet of the

or the acceleration switch 36 controlled by the negative braking cycle depth comparator 40 in this case

ven inlet of the brake cycle depth comparator 40. The mode of operation is the brake cycle depth signal larger

The sum of this signal forms at the negative inlet as the brake cycle depth reference signal at the negative

Brake cycle depth comparator 40 a reference value, 55 inlet of the brake cycle depth comparator 40, if the

which ends with the brake cycle depth signal from the brake cycle control signal from the delay switch 30 and

depth integrator 32 is compared. In the execution example, the brake release signal remains until the brake cycle

backlash corresponds to the saturated outlet of the deceleration class depth falling below the braking cycle depth reference signal

tion amplifier 34 corresponds to a braking cycle depth 4.8 km / h and the outlet of the acceleration ω movements reached optimal braking conditions switch 36 when sensing the upper acceleration - With low load on the vehicle and / or small

level also provides a braking cycle depth based on the friction coefficient of the road surface due to the brake release

Speaking 4.8 km / h. Furthermore, the wheel speed lock switch 38 represents a third mode of operation gnal from conductor 28 at the negative inlet of the braking / braking cycle depth signal from the braking / braking cycle depth comparator 40 maintains a part of the reference indicator 38 as long as the brake is released

Gnals that about 2.4 km / h for every 16.1 km / h travel speed until the brake release lock switch 38 is reapplied

the brake demands when the wheel acceleration

The brake release lock switch 38 is normally set to a low value which indicates

ίο

that the wheel speed approaches the driving speed. At this low level of acceleration delivers the brake release lock switch 38 the brake release lock signal to clear the brake release signal and that To bring about reapproximation of the brake. This mode of operation gives the specified driving conditions optimal braking behavior. The remaining parts of the control system shown in Fig. 1 are used for self-control, to report errors in the control system and, if errors occur, to switch off the control system to effect.

For this purpose, a test circuit 48 is provided for the speed sensors 14 and 16, which sends an error signal to a timer 50 if one of the circles of the speed sensors 14 and 16 is sensed as being interrupted. Another error signal is fed to the timer 50 from the power supply 52, for example the vehicle battery, if its voltage B + falls below the operating voltage Z -t- uci Sicueianlege sifiki. The peeling off

The outlet of the test circuit 58 causes the brake to be released over the maximum time limit until the test circuit described above gives a switch-off signal for the control system supplies.

In Fig.2a and 2b of the drawings is a Circuit diagram of the control system according to FIG. 1 shown in more detail.

A regulated voltage source 52 supplies a regulated operating voltage Z + for the control system. One

ίο Vehicle battery has an unregulated voltage B + and is in a circuit made up of a resistor 60, a Zener diode 62 and a resistor 64. The Zener diode supplies a regulated voltage which is connected to the base electrode of an NPN transistor 66, the collector electrode of which is on the battery lies. The transistor 66 is loaded into the conductive state to the regulated voltage Z +, which reduces the voltage at the cathode of the Zener diode 62 by the voltage drop between the base electrode and the emitter'.ek-

Circuit 42 also supplies an error signal to the timer 20 trodc in transistor 66 is the same to be supplied. The Span-50, if in the excitation circuit of the magnet 44 a sub-zero Z + is tapped at a resistor 68.

The remainder of the voltage source 52 is used to provide an error signal if the battery voltage B + becomes lower than the desired operation

net is or has a ground fault or remains energized to release the brake for a time that exceeds a specified Time limit which is a function of the

breakage or an earth fault occurs.

The timer delivers its output at the trigger level to a comparator circuit 54 if one of the error signals from the test circuit 48 is longer than a predetermined 25 voltage Z + of the control system, which is present at the correct time or if the brake release magnet 44 is necessary. This error signal is generated by means of

of an NPN transistor 70, the emitter electrode of which grounded and its collector electrode connected to the emitter electrode of transistor 66 via a resistor

Brake cycle depth signal from Bremszyklustiefeninte- 30 is connected. If the battery voltage B + grator32ist is above the breakdown voltage of the Zener diode 62, then

The comparison circuit 54 then provides a switch-off signal, the voltage drop in the resistor 64 is sufficient to signal to the switch-off circuit 42 to make the brake release magnet conductive, so that the voltage 44 is de-energized and the brake release is terminated at its collector electrode is close to the ground or around the excitation of the brake release magnet and thus 35 potential. However, the battery voltage B + should prevent the brake from being released. the breakdown voltage of the Zener diode 62 decrease, so

In order to prevent a wrong worker of the control system, the transistor 70 is blocked and the voltage on if due to a sensed error, its collector electrode rises to about the battery position, although it is prevented from releasing the vehicle brakes, voltage B + to send an error signal via a Diode 73 when a brake release signal is present, the comparison 40 is to be supplied. This error signal can be blocked via a conductor 74 circuit 54, depending on whether the controller is supplied to the timer 50.

system requires ventilation or not. The square wave amplifier 18 contains a resistor

The comparison circuit 54 receives a signal from the output 76, which is in series with the output coil of the speed circuit 42, which represents the outlet of the control system sensor 14 between the operating voltage Z + and. If an error is detected and corrected itself, 45 is ground. The alternating current output of the speed sensor while the control system is applying the brake controller 14, which acts as a measure of the speed of the vehicle wheel, if the switch-off signal from the comparison circuit 10 is on one side of the vehicle axle, it is with the ses 54 only as long as the error signal is present. If, however, there is a positive inlet of a functional amplifier 78, the error signal is also only briefly connected to resistors 80 and 82 in series at the same time. The one brake release signal from the brake cycle depth comparison 50 operating voltage Z + is present at the connection point between 40, so the comparison circuit 54 supplies the appearance of the resistors 80 and 82 via a condensing signal for the longer-lasting signal. In this way, the brake release signal blocks the converter 78 via a resistor 86. A pre-equalization circuit 54 to block the voltage at the negative inlet of the functional amplifier switch signal during its duration. When the Aus55 ker 78 disappears, provided by a voltage divider, the switching signal, the control system works again in the series-connected resistors 88 and 90 between

prescribed way.

The error signal of the comparison circuit 54 is fed to a warning lamp circuit 56 in order to give the driver the Indicate the presence of an error.

For further testing of the speed sensor 14 and a dynamic test circuit 58 is also provided, the the wheel speeds of the tachometer generators 22 and monitored and an outlet to the brake cycle depth

between the operating voltage Z + and ground is a feedback resistor 92 is between the outlet of the operational amplifier 78 and its positive inlet.

The functional amplifier 78 and the remaining functional amplifiers in the control system according to Fig..2a and 2b are current amplifiers, the current at the positive Inlet disconnected from the flow at the negative inlet

comparator 40 supplies in order to initiate a brake release - it is pulled and for which a positive output is removed, when the speed of one wheel stands the other tks when the current is more positive. Let in the stream Rades by a predetermined value, which exceeds im at the negative inlet. Furthermore, the radio embodiment chosen according to 27 km / h, the booster normally has a large outlet,

when no current is supplied to the inlets. Of the In-load current generated by the voltage divider of d ^ n resistors 88 and 90 to the negative inlet of the The friction amplifier 78 is fed in, serves as a bias voltage for the output of the functional amplifier 78 at ground potential. The square wave amplifier 18 speaks to the alternating current signals of the speed sensor 14 and delivers a square wave of the same frequency.

The square wave amplifier 20 includes resistors 94, 96, 98, 100, 102, 104 and 106, a capacitor 108 and a functional amplifier 110, which is connected in the same way as the square-wave amplifier 18 to a To deliver square wave of the same frequency as the alternating current signal, which the speed sensor 16 accordingly the speed of the vehicle wheel 12 supplies.

The square wave of the square wave amplifier 18 is fed to a differentiator circuit in the tachometer generator 22, which consists of a resistor 112 and a capacitor 114. A püäiiivci Sirumpuls will be the positive input of a functional amplifier 116 through a diode llfc on each leading edge of each Square wave is fed to the square wave amplifier 18 and a negative current pulse is applied to the negative inlet of the functional amplifier 116 via a diode 120 at each trailing edge of each square wave of the Rectangular amplifier 18 supplied. The negative inlet of the operational amplifier 116 is through a capacitor 122 in mass. A feedback capacitor 124 is located between the output of the motion amplifier 116 i'.nd its negative inlet to an integrator create, the integration of which is determined by a feedback resistor 126 parallel to the Capacitor 124 is located. The output of the operational amplifier 116 is an analog voltage that is directly proportional the speed of the vehicle wheel 10 is.

The tachometer generator 24 includes resistors 128 and 130, capacitors! 32,! 34 and! 36, diodes 138 and 140 and a function amplifier 142, which works in the same way as the function amplifier in the tachometer circuit 22 is switched. The output of the tachometer generator 24 is an analog voltage of magnitude that is directly proportional the speed of the vehicle wheel 12 is.

The speed selector 26 responds to the wheel speed signals of the tachometer generator circuits 22 and 24 and provides a wheel speed signal to the conductor 28 corresponding to the lower speed of the vehicle wheels 10 or 12 Resistor 148 is connected to the regulated operating voltage Z + . The wheel speed signal of the tachometer generator 22 is fed to the base electrode of the transistor 144 and the wheel speed signal from the tachometer generator 24 is fed to the base electrode of the transistor 146 conductive transistor 144 or 146.

The delay switch 30 includes a filter resistor 150 which is in series with a capacitor 152 which is connected between the conductor 28 carrying the wheel speed signal and a summing point 154. The inlet to summing point 154 from capacitor 152 is a current, the magnitude of which represents the wheel acceleration This acceleration signal ! is combined at summing point 154 with a current the magnitude of which is a reference deceleration corresponding to the maximum vehicle deceleration. This delay reference signal consists of two parts. The first part is a constant current to the summing point 154, which is fed from the operating voltage Z + via a resistor 156, while a second part is a current whose strength is proportional to the wheel speed ^; st and the summing point 154 is fed from the conductor 28 via a resistor 158. The deceleration reference signal shown at the summing point 154 corresponds to a wheel deceleration of 0.9 g at zero wheel speed and increases to 1.3 g for a speed corresponding to 96 km / h.

The outlet at summing point 154 which is the sum of the wheel acceleration signal and the deceleration reference signal is connected to the negative inlet of a functional amplifier 160 via a resistor 162 and a diode 164 supplied. Between the anode of the diode 164 and the outlet of the function amplifier 160 is a diode 166 to remove a speed threshold introduced by the diode Ϊ64. Of the positive inlet of operational amplifier 160 is grounded.

A feedback filter capacitor 168 is between the output of operational amplifier 160 and the summing point 154 provided.

In the absence of a wheel deceleration and for wheel decelerations that are smaller than the reference deceleration, the delay reference signal fed to summing point 154 via resistors 156 and 158 is sufficient and is connected to the negative inlet of the operational amplifier 160, out to the operational amplifier to be brought to ground potential at the outlet. During wheel decelerations, the capacitor is used 152 Current subtracted from summing point 154, the fraction being a function of the amount of wheel deceleration is. Is the wheel deceleration such that the current through capacitor 152 matches the deceleration reference current comes soon, in which case a Bioekier danger is indicated, the outlet of the function amplifier switches 160 to a positive voltage which contains the control signal from the delay switch 30. Of the Resistor 162 determines a wheel speed change required before the negative inlet of the operational amplifier 160 can be reduced to zero, to effect the control signal.

The control signal is fed to the brake release blocking circuit 38 via a diode 170 in order to generate the brake release blocking signal to end. For this purpose, it is fed to the brake cycle depth comparator 40 via a diode 172, to release the brake.

As a result of the dead times in the brake system, the brake pressure will continue to rise after the control signal is present by the deceleration switch 30, so that a greater wheel deceleration occurs than that Corresponds to the threshold value of the reference delay. The decreasing speed signal in conductor 28 lowers the Voltage at summing point 154 and the reference delay current to summing point 154 seeks the voltage at summing point 154 approximately to the threshold value of the delay. The decreased tension at summing point 154 represents the amount of deviation of the wheel speed from a deceleration reference speed approximately corresponding to the threshold value. If the wheel deceleration ends and the wheel begins again To accelerate, the voltage at the summing point i54 increases as the deviation approaches the wheel speed from the time integral of the reference deceleration to zero, at which point in time the Current to the negative inlet of the operational amplifier

160 to terminate the control signal.

The control signal is fed to the positive inlet of a function amplifier 174 in the brake cycle depth comparator 40 via a resistor 176

The Bremszykl'istiefenintegrator 32 includes a filter resistor 1/8, which is in series with a differentiating capacitor 180 between the wheel speed signal-carrying conductor 28 and a summing junction 182. The summing junction 182 of the inlet

Since the delay reference signal which is fed to the summing point 182 via the transistor 184 corresponds approximately to the delay reference signal of the delay switch 30 which is fed to the summing point 154 , the brake cycle depth signal of the brake cycle depth integrator has a magnitude that essentially represents the magnitude of the change in the wheel speed during the presence of the brake release signal occurs This is the brake cycle depth ver-

A current of a strength equal to 40 is supplied from the capacitor 180 in such a way that the size of the braking cycle corresponds accordingly the wheel acceleration. This acceleration depth signal of the braking cycle depth integrator actually A measure of the size of the changes in wheel speed is that during the duration of the brake release signal occurs The brake cycle depth signal is applied to the positive inlet of function amplifier 174 des Brake cycle depth comparator 40 via a resistor 202 forwarded

While the brake is being released, the transistor 184 is blocked and the capacitor 190 discharges via the

Operating voltage Z + is a capacitor 190 is 20 resistor 188. The speed of the discharge of the parallel to resistor 188. capacitor 190 is related to the delay

The reference delay current becomes the summation reference current at summing point 182, during point 182 fed through the transistor 184 when the transistor 184 is conductive so that at the ends of the The brake release signal is conductive and the resulting conductive

The sum of the vehicle acceleration signal and 25 become a surge current through the transistor 184

The transmission signal is optionally combined at summing point 182 with a current which has a reference delay of 1.0 g, which is approximately equal to the reference delay of the delay switch 30, and the rest represents the maximum possible vehicle deceleration The reference deceleration current is optionally through a PNP transistor 184 and resistors 186 and 188 provided between the summing point 182 and the

of the delay reference signal is applied to the negative input of an operational amplifier 192 through a diode 194
The positive inlet of the operational amplifier 192

Resistance 186 occurs resulting from the recharging of the capacitor 190 and a strength and The duration of which the strength of the braking cycle depth signal of the braking cycle depth integrator is fixed at a value in bulk. A diode 196 is placed between the anode 30, which corresponds to the brake cycle depth signal of the diode 194 and the outlet of the function amplifier would assume this if the reference delay 192 is provided in order to continuously output the counter signal through the diode 194 to the summing point 182 via the to remove the speed threshold. The function transistor 184 would be fed. Is the middle wheel amplifier 192 has a feedback capacitor 198 lag less than that across resistors 186 and

35

between its outlet and summing point 182 to form an integrator.

The output of the operational amplifier 192 is normally held at ground potential through the delay applied to summing point 182

188 supplied deceleration reference signal, the braking cycle depth signal is! of the brake cycle depth integrator brought back to ground potential. However, if the mean value of the wheel deceleration exceeds that of the Resistors 186 and 188 supplied delay control

reference current. If, however, the train signal from the summing 40, then the brake cycle depth signal is on the point 182 set by the capacitor 180 as a result of a previously mentioned value Wheel deceleration current outflowing the current to the wheel deceleration under the reference deceleration signal Exceeds summing point 182 via transistor 184, causes a progressive increase in the level the output of the function amplifier the brake cycle the brake cycle depth signal is reset, cliff-depth signal. This is the integral of summation 45. This is reflected in the increased current to the positive

of the currents until the integral returns to zero or ground potential reached whereby the limit of integration is determined.

The conductivity of transistor 184 is determined by the brake release signal from the outlet of the brake cycle depth comparator 40, which is connected to the base electrode of the transistor 184 via a resistor 200 is. In the absence of a brake release signal, the outlet of the brake cycle depth comparator 40 has ground potential and transistor 184 is biased to conduct the delay reference current to summing point 182. When a brake release signal occurs, the transistor 184 is blocked, so that the brake cycle depth integrator only the wheel acceleration signal is integrated

Inlet of the functional amplifier 174 via the resistor 202 again.

The delay amplifier 34 includes an operational amplifier 204 with its positive input connected to ground lies. A filter resistor 206 and a differentiating capacitor 208 are connected in series between the the wheel speed signal leading conductor 28 and a summing point 210 is provided. The current through the Capacitor 208 represents the wheel acceleration. This signal is added to the negative inlet of the function amplifier 204 fed through a diode 212 between the outlet of the functional amplifier 204 and the Summing point 210 is a feedback filter capacitor 214, to which a resistor 216 is connected in parallel.

and the summing point 182 is switched via the resistor 180 & q,

feeds. The braking cycle depth signal is thus a to- The delay amplifier 34 supplies a first

Composite signal, the first part of which is the value part of a Brcmszykiustiefe reference signal, which is one of the

represents by which the time integral of the delay vehicle delay has a proportional amount until the

train signal the wheel speed during the application of the at a predetermined delay level, which in the

Brake exceeds and the second part of which is the integral 65 Ausführungsbeispiei 0.8 g, is saturated. Thereafter

the wheel acceleration is during the brake release, a further wheel deceleration causes a decrease in the

wherein the composite signal has a lower In voltage at summing point 210, while the current

integration limit of zero. through resistor 216 to summing point 210

seeks to restore the tension to the level of about 0.8 g. The voltage at summing point 210 then represents the deviation of the wheel speed from a reference speed, which is delayed in accordance with the delay represented by the feedback through resistor 216. The wheel starts to accelerate and the voltage at summing junction 210 according to the approach of the deviation of the wheel speed to zero, so the outlet of the first portion decreases the operational amplifier 204 again to ground potential of the braking cycle depth reference signal from the delay amplifier 34 in the saturation state in the exemplary embodiment a value corresponding to 4.8 km / h.

The delay amplifier 34 is designed so that the control signal supplied by the delay switch 30 is always terminated before the outlet of the delay amplifier 34 goes out of saturation to ensure that the first part of the braking cycle depth reference signal of the delay amplifier 34 is at 4.8 km / h corresponding level is when the delay switch 30 terminates the control signal

The Beschleunigungsbchalter 36 includes a filter resistor 218 which is in series with a differentiating capacitor 220 between a summing junction 221 and a filter 224 of a wheel speed signal representing feeds the filter 224 composed of a resistor 226 and a connected in series to capacitor 228, between the conductor 28 and Mass ·; lie. The voltage across capacitor 228 is a filtered wheel speed signal. The current at the inlet of summing point 221 through capacitor 220 represents the wheel acceleration. A resistor 222 is connected between summing point 221 and ground. The summing point 221 is connected via a resistor 232 to the base electrode of a PNP transistor 230, the emitter electrode of which is connected to the regulated operating voltage Z + and the collector electrode of which is connected to the negative inlet of a functional amplifier 234 via a resistor 236.The positive inlet of the functional amplifier 234 becomes Operating voltage Z + fed in via a resistor 238

The base of transistor 230 is grounded through resistors 222 and 232 and is normally conductive. The outlet stream from the summing point 221 via the resistor 222 has a size that represents a Radbezugsbeschleunigung, which in the exemplary embodiment is 2.0 g This acceleration reference signal is combined in summing junction 221 with the wheel acceleration signal that comes from the differentiating capacitor 220th In the absence of wheel acceleration and also in the case of wheel accelerations below the reference acceleration represented by the current through resistor 222, the current from summing point 221 through resistor 222 is sufficient to make transistor 230 conductive. In the times of wheel acceleration, the capacitor 220 supplies current to the summing point 221 in a quantity that is a function of the wheel acceleration. If the wheel acceleration is such that the current through capacitor 220 is equal to the acceleration reference current, transistor 230 is blocked. Resistor 232 determines a value for the wheel speed change that is required before transistor 230 is turned off.

The operational amplifier 234 acts as a current and voltage amplifiers and also causes a phase inversion so that its outlet has g a high level for accelerations above 2.0 This high level of the acceleration switch 36 includes a second portion of the braking cycle depth reference signal, for example, according to a braking cycle depth corresponding 4.8 km / h is selected

The two portions of the braking cycle depth reference signal from deceleration amplifier 34 and acceleration switch 36 are connected to anodes 240 and 242 in grid 46, respectively. The cathodes of diodes 240 and

ίο 242 are connected to the negative inlet of the function amplifier 174 in the brake cycle depth comparator 40 via a resistor 244 . The diodes 240 and 242 cause a coupling of the higher part of the braking cycle depth reference signal with the radio

IC amplifier 174.

The wheel speed signal in conductor 28 goes to the negative inlet of functional amplifier 174 of the Bre * cycle depth comparator via resistor 246 . The current inlet to the function amplifier 174 through the resistor 246 contains a third part of the braking cycle depth reference signal and can, for example, be a braking cycle depth corresponding to 2.4 km / h for every 16 km / h wheel speed. The brake cycle depth reference signal composed of these three parts is compared with the brake cycle depth, which is represented by the size of the brake cycle depth signal of the brake cycle depth integrator 32, in order to determine the duration of the brake release in detail and thus the operation of the control system.

The brake release blocking circuit 38 contains a filter resistor 245 and a differentiating capacitor 247 lying in series with it, which are located between the outlet of the filter 224 and the negative inlet of a function amplifier 248 . Capacitor 247 provides an acceleration signal to the negative inlet of operational amplifier 248. A feedback filter capacitor 250 is provided between the outlet of operational amplifier 248 and its negative inlet.

A first part of an acceleration reference signal for the brake release blocking circuit 38 is a constant current from the operating voltage Z +, which is connected to the positive inlet of the functional amplifier 248 via a resistor 252. A second portion of the acceleration reference signal is a current having a magnitude proportional to the braking cycle depth which is supplied to the negative inlet of the operational amplifier 248 via a resistor 254 which is connected to the outlet of the braking cycle depth integrator 32 . The total acceleration reference signal that is fed to the inlets of the function amplifier 248 represents the wheel speed approaching the vehicle speed and can be, for example, a wheel acceleration of 0.5 g with a braking cycle depth of zero, which decreases to 0.1 g when the braking cycle depth has a maximum value.

If the wheel decelerates or if the acceleration is less than the reference acceleration, then the function amplifier 248 supplies the brake release blocking signal to the negative inlet of the function amplifier 174 in the brake cycle depth comparator 40 via a diode 256 and a resistor 258.

The brake release lock signal is cleared when the wheel acceleration exceeds the acceleration reference signal. It is also cleared by the control signal of the delay switch 30 connected to the negative input of the operational amplifier 248 through a resistor 260 . The brake release lock signal is

effective again when the control signal ends and when the wheel acceleration falls to the low reference acceleration value decreases, which results when the wheel speed approaches the driving speed

In addition to the elements already mentioned, the braking cycle depth comparator 40 contains a resistor 262 between the regulated operating voltage Z + and the positive inlet of the function amplifier 174 to remove the bias voltage introduced in the speed selector 26 by the voltage drop in the emitter-base path of the transistors 144 and 146. A feedback resistor 264 is located between the positive inlet and the outlet of the function amplifier 174, whereby a feedback current occurs during a brake release signal which is equal to the third part of the brake cycle depth reference signal and is proportional to the wheel speed when the wheel speed is 40 km / h, for example

Resistors 176, 202, 244 and 246 and 258 are like that sized, dafc aer the negative inlet of the functional insurer 174 current fed through resistor 258 during a brake release lock signal from Brake release blocking circuit 38 is greater than the current fed to the positive inlet via resistor 202 maximum values of the brake cycle depth signal from the brake cycle depth integrator 32. Further, the current to the positive inlet through resistor 176 during a control signal from the delay switch greater than the maximum total brake cycle depth reference signal presented to the negative inlet through the resistors 244 and ΙΊ6 is supplied. The brake cycle depth integrator 32 is therefore unable to cause a brake release and the delay switch 30 is itself effective to the brake release signal i-nd the resulting To cause the brake to be released when the risk of blocking is sensed. It also causes the brakes to be released to hold as long as the control signal is present. The brake release lock signal of the brake release lock circuit can also 38 always request that the brake be applied.

The disable circuit 34 includes a Darlington transistor 266, which is controlled by the Bremslüftsignal, and a Darlington transistor 268, which prevents the ¹ th Abolition of the control system effected and a release of the brake when Abfühien certain error in the system. The transistors 266 and 268 are connected to one another in series via the vehicle battery with the voltage B + via a resistor 270, a resistor 272 and a resistor 274. The emitter electrode of the transistor 266 is connected to the base electrode of an NPN transistor 276, the emitter electrode of which is connected to ground and the collector electrode of which is connected to one side of the brake release magnet 44. The connection between the resistors 270 and 272 is connected to the base electrode of a PNP transistor 278, the emitter electrode of which is connected to the battery voltage B + and the collector electrode of which is connected to the other side of the brake release magnet 44. A resistor 280 is connected between the emitter electrode and the collector electrode of transistor 278,

Shutdown transistor 268 normally receives a positive voltage from conductor 282 and a resistor 284 by the test group in the absence of errors in the system. The transistor 268 is therefore normally switched on when the control system is working properly.

The brake release signal from brake cycle depth comparator 40 is applied to the base electrode of transistor 266 connected through a resistor 286. The brake release signal causes a load on transistor 266 in the conductive state, which in turn turns the transistor 276 conductive to ground potential

to bring one side of the brake release magnet 44. At the same time, the current through the resistors 270 and 272 biases the transistor 278 in order to make it conductive, so that the battery voltage B + is transferred to the other side of the brake release magnet 44

ίο which is thus excited, comes to the release of the vehicle brake to effect while the brake release signal from the brake cycle depth comparator 40 is present. When the brake release signal ends, the transistor 266 is blocked, so that the brake release magnet 44 current- -os and the brake is applied again

The mode of operation of the control system according to the circuit diagrams according to FIGS. 2a and 2b will be explained with reference to FIGS. 3a to 3d, the three different modes of operation being shown. In each of FIGS. 3a to 3d, curve A represents the size of the wheel speed which changes after the rough brakes are released. Curve B is a reference wheel speed which decreases according to the reference deceleration in deceleration switch 30. Curve C is a reference wheel speed that decreases according to the reference deceleration in deceleration booster 34, and curve D is the braking cycle reference depth provided to braking cycle depth comparator 40 from deceleration booster 34, acceleration switch 36, and conductor 28.

The control system begins to control the braking of the vehicle when the brakes are applied and the wheel deceleration exceeds the reference deceleration of the deceleration switch 30. Here the Control system three ways of working to ensure optimal braking behavior with different vehicle loads and different friction levels in the roadway to enable. In all three modes of operation, the delay switch 30 itself is effective in order to release the brake to cause when the wheel deceleration exceeds the reference deceleration caused by it, whereby the risk of blocking is displayed.

In the first mode of operation, the duration of the brake release is controlled solely by the delay switch 30. This mode of operation generally takes place when the vehicle is heavily loaded and / or the road surface has a high coefficient of friction, under which conditions the braking cycle depth during brake release is shallow and short. These relationships are shown in Fig. 3a. 1.Ti time fo the wheel deceleration exceeds the reference deceleration, so that the deceleration switch 30 supplies the control signal to the brake release lock circuit 38 to clear the brake release lock signal, and also to the brake cycle depth comparator 40, which supplies a brake release signal to energize the brake release magnet 44. As a result of the dead times in the brake system, the brake pressure continues to rise after the brake release magnet 44 has been energized, so that the wheel is decelerated below the amount given by the deceleration switch 30. This is shown in the braking cycle depth signal (curve A). At time t \ , the braking depth becomes greater than the reference braking cycle depth (curve D). At time t ₂ , the wheel deceleration ends as a result of the decreasing brake pressure that results when the brakes are released, and the wheel begins to accelerate again to travel speed. At the time u

the braking cycle depth decreases to below the braking cycle depth reference values (curve D) . However, the brake release signal is retained at the outlet of the brake cycle depth comparator 40, since the control signal is still supplied by the delay switch 30. At time U , the deviation of the wheel speed from the reference speed (curve B) is reduced to zero, so that the control signal of the delay switch 30 ends of the brake cycle depth comparator 40, thereby causing a reapplication of the braking. The release of the brake release signal causes the brake cycle depth signal to be reset to ground potential, the mean value of the wheel deceleration being smaller than the reference deceleration in the brake cycle depth integrator 32. Then the wheel acceleration ends and the deceleration of the wheel begins depending on the increasing brake pressure. The braking cycle is repeated in the manner described until the vehicle comes to a standstill or the vehicle brakes are released by the driver or other road surface properties or loads occur, whereby the operation of the control system is changed. This mode of operation, in which the delay switch 30 controls the duration of the brake fan, results in optimal braking behavior when the vehicle is heavily loaded and / or the road surface has a high coefficient of friction.

In the second mode of operation of the control system, the duration of the ventilation is controlled by the brake cycle depth signal of the brake cycle depth integrator 32. This mode of operation is given with an average coefficient of friction of the roadway and / or average load on the vehicle, where the braking cycle depth is greater and longer during the brake fan than in the first mode of operation. 3b and 3c referenced. At time f ₀ , the wheel deceleration exceeds the reference deceleration, which indicates the risk of locking and the deceleration switch 30 supplies the control signal to clear the brake release lock signal and to initiate the brake release signal, as is the case with the first operating mode. When the vehicle brakes are released, the wheels are decelerated further, as indicated by curve A of the braking cycle depth, as a result of the dead times in the braking system. As a result of the lower coefficient of friction of the roadway and the lower vehicle load, the braking cycle depth is generally greater and also has a longer duration than in the first-mentioned case.

At time ii, the braking cycle depth (curve / V is greater than the reference braking cycle depth (curve D). At time h , the wheel deceleration ends and the wheel begins to accelerate towards the driving speed, since the braking forces decrease. In Fig. 3b the wheel reaches a maximum acceleration of less than 2 g, which is given by the acceleration switch 36 as the reference acceleration and in Fig. 3c a maximum wheel acceleration greater than 2 g is achieved. At time / 3, the deviation of the wheel speed from the reference speed is reduced (curve B) the retarder booster g <addrehzahl 34 in F i 3b; according to the influence of the delay switch 30 to zero and the time delay switch 30 deletes the control signal, but is at the braking cycle depth h is still greater than the reference braking cycle depth (curve D) passing through the '.. and the acceleration switch 36 in Fig. 3c is determined so that the brake release signal from the brake cycle depth comparator 40 is recorded remains intact.

According to FIG. 3b, the size of the brake cycle depth decreases to below the reference brake cycle depth at time £ 4, whereby the brake release signal of the brake cycle depth comparator 40 ends and the brake is reapplied. According to FIG. 3c, the deviation of the wheel speed from the reference speed (curve C) is reduced to zero at time U , the output of the deceleration amplifier 34 being reduced to ground potential. which exceeds 2 g. The brake cycle depth reference signal thus remains unchanged and the brake release signal is maintained by the brake cycle depth comparator 40. At the moment in Fig. 3c, the braking cycle depth decreases to below the reference braking cycle depth, at which time the Brem.sliiftv.5na] is deleted. reapplying the brake ri! cause.

When clearing the brake release signal according to Fig. 3b and 3c, the braking cycle depth signal is reset to ground potential, it being assumed that the The mean value of the wheel deceleration is smaller than the reference deceleration in the braking cycle depth integrator 32. Thereafter if the wheel continues to accelerate for a certain time and then begins to decelerate again as a result of the applied brakes. This braking cycle is repeated several times, if necessary, until the vehicle to The vehicle comes to a standstill, or the vehicle brakes are released by the driver, or other surface properties the road surface or the load on the vehicle a transition to another mode of operation of the Initiate control system. This second mode of operation of the control system according to FIGS. 3b and 3c is suitable under the given conditions of average vehicle load and average friction coefficients of the roadway optimal braking conditions by controlling the duration of the brake fan through the brake cycle depth integrc.or to obtain.

Ip, F i g. 3d illustrates the third mode of operation of the control system, in which the duration of the brake fan is controlled by the brake release lock circuit 38. This mode of operation is suitable for a low coefficient of friction on the road surface and / or light vehicle loads, in which the braking cycle depth when the brakes are released becomes deeper and longer than in the two aforementioned modes of operation. As with these, the brake release is initiated at the time fo when the wheel deceleration exceeds the reference deceleration of the deceleration switch 30, in that the deceleration switch 30 supplies the Sfeuersijviil. This clears the brake release lock signal and generates the brake release signal. At time u , the braking cycle depth (curve A) exceeds the reference value for the braking cycle depth (curve D). The wheel deceleration ends at time f ₂ and the wheel begins to accelerate as a result of the decreasing braking forces. Because of the low coefficient of friction of the roadway and / or the low vehicle load, the wheel acceleration remains below the reference value of 2 g given by the acceleration switch 36, but is greater than the reference acceleration given by the brake release locking circuit 38. At time / 3 is the deviation of the wheel speed! from the reference speed (curve B) corresponding to the delay switch 30 to zero, whereupon the delay switch 30 cancels the control signal.

However, the brake cycle depth is still greater than the reference brake cycle depth, which is given by the wheel speed signal and the delay amplifier 34, so that the brake release signal is maintained by the brake cycle depth comparator 40. At time / ₄ , the deviation of the wheel speed from the reference speed (curve C) is reduced to zero and the outlet of the delay amplifier 34 is lowered to ground potential The reference acceleration of 2 g, which is given by the acceleration switch 36, is. The braking cycle depth remains greater than this low reference value, so that the brake release signal from the braking cycle depth comparator 40 is maintained.

At time / 5, the wheel acceleration falls below the Bcztigsbcschicüni ^ nn ", which is given by the Brernslüits ^ srrkreis 38, whereby the approach of the wheel speed to the driving speed is indicated. The brake release lock signal is therefore fed to the brake cycle depth comparator 40, whereby the brake release signal is deleted and the brake is reapplied he follows

If the vehicle is lightly loaded and / or the road surface has a low coefficient of friction, this results in Way optimal braking conditions, whereby the control system is able to adapt to all possible operating conditions.

In all modes of operation of the control system, the transistor 184 in the brake cycle depth integrator 32 is in the Blocked time in which the brake release signal is present. During this time, the capacitor 190 discharges before has been charged through resistor 188, through resistor 188 to an extent that corresponds to the reference delay when transistor 184 is conductive. When the brake release signal is deleted, transistor 184 becomes conductive again and the resulting current pulse becomes negative inlet of operational amplifier 192 is such that capacitor 190 is charged and that Brake cycle depth signal is set to the value which it would have achieved if the transistor 184 had been switched continuously in the conductive state and the the reference delay supplied by it would have progressively been added to the wheel acceleration signal. If the mean value of the wheel deceleration is less than the reference deceleration fed in when transistor 184 is conductive, the braking cycle depth signal becomes set to ground potential when one of the brake release signals ends indicates possible vehicle deceleration, the braking cycle depth signal is set to a positive level that is equal to the level it would have reached, if the reference deceleration was continuously added to the vehicle acceleration signal while the brake release signal is present, the mean value remains of the wheel deceleration above the reference deceleration level, the braking cycle depth signal is progressively adjusted to a higher level until the outlet of the braking cycle depth integrator is greater than that via the brake release Reference brake cycle depth signal fed to resistors 244 and 246 has ends around the brake release signal of the control signal of the delay switch 30 to maintain, so that the wheel speed of the Fahr speed can approach. This prerequisite can be given, for example, if the vehicle brakes are small by the driver on a roadway Coefficient of friction can only be applied gently, so that the braking cycle depth is similar to braking on a The roadway runs with a high coefficient of friction and so the control system works in the first mode of operation. If the brake cycle depth signal reaches a sufficient size to allow the brake to be released after the To maintain the control signal, the reapplication of the brakes is generally in accordance with the third mode of operation controlled so that the wheel speed is again up to the vicinity of the driving speed can increase. In this way it is prevented that a blocking condition is reached which could otherwise occur.

The remaining parts of the circles in FIGS. 2a and 2b are directed to the test circuits for switching off the control system, with errors detected in the following the control system provides for the brake to be applied and for the brake to be prevented from being released.

The timer 50 has a power inlet to the negative inlet of the operational amplifier 288 from the outlet of the shutdown circuit 42 via a conductor 293, a diode 294 and a resistor 296. This current comes Via the shutdown circuit 42 from the vehicle battery via the resistor 280 and the brake release magnet 44, when the transistor 276 is blocked if the brake release magnet 44 is caused by a short circuit or a Interruption not working properly This current, which is insufficient to excite the Brerrxlüftmagneten, is greater than the bias voltage on the amplifier 288 via resistor 292 in timer SO, so that its outlet normally has ground potential, provided that there are no additional inlets to amplifier 292.

The timer 50 also receives power to the negative input of amplifier 288 at a magnitude equal to Brake cycle depth signal when working the control system is proportional This current is via the brake cycle depth integrator 32 via conductor 298, resistor 300 and resistor 296.

When initiating a brake release, wherein the transistor 276 is switched on, or when the circuit is interrupted or there is a ground fault in the Brake release solenoid 44 terminates power to timer 50 through conductor 293 and the outlet of the amplifier 288 begins to integrate positively as a result of the current flowing through resistor 292, namely in Function on the current through conductor 298 corresponding to the brake cycle depth The outlet of the timer integrated up to the trigger level of the comparison circuit 54, this time being based on an excessively long brake release that occurs with increasing brake cycle depth gets bigger. At the end of the brake release or the elimination of the error on the brake release magnet 44, the timer integrates backwards down to ground potential.

The timer 50 also receives a leakage current at the positive inlet of the amplifier 288 from the speed sensors via the speed test circuit 48 which controls the rotation number sensors 14 and 16 monitored

The test circuit 48 includes an NPN transistor 302, the collector electrode of which is connected to the battery voltage B + via a resistor 304 and the emitter electrode is connected to the positive input of the functional amplifier 288 of the timer 50 on the non-grounded side of each of the speed sensors 14 and 16 is with the base electrode of transistor 302

connected via associated resistors 308 and 306. A filter capacitor 310 is connected to ground between the base electrode of transistor 302.

The base electrode of transistor 302 is normally close to ground potential via the low impedance of speed sensors 14 and 16. Are the Speed sensors 14 and 16 in the error-free state, is therefore Gi '. ■ · Transistor 302 blocked. Should an interruption of the circuit occur in one or both of the speed sensors 14 and 16, the voltage is applied the base electrode of transistor 302 is increased by the supplied operating voltage Z +, which is generated via resistors 76 and / or 94 and resistors 306 and / or 308 is forwarded. This voltage is sufficient to switch the transistor 302 on, so that a fault indicating current is supplied to the positive input of operational amplifier 288 in timer 50. This Current, combined with the bias current via the resistor »2, always exceeds the current used for the negative inlet of the functional amplifier 288 flows, so that the outlet of the functional amplifier integrates positively and the switching point of the comparison circuit 54 reached after a specified time. Ending of the error signal causes the timer 50 to integrate downwards in the direction of ground potential.

The fault current which is fed from the regulated power source to the positive inlet of amplifier 288 via conductor 74 when the battery voltage B + falls below the regulated operating voltage Z + has already been described. This fault current acts in the same way as the fault current for failure of the speed sensor and causes the outlet of the functional amplifier 288 to be integrated in the positive sense and to reach the switching point of the comparison circuit 54 after a predetermined time If the battery voltage B + increases again and exceeds the operating voltage Z - r, So ends the Fchlcfsiföm and the outlet of the timer 50 integrated again downwards in the direction of ground potential.

The outlet of the timer 50 is connected to the negative inlet of a function amplifier 312 of the comparison circuit 54 through a resistor 314. A bias current is fed to the negative inlet via a resistor 316 which is between the operating voltage Z + and the negative inlet The inlet is via a diode 322. The anode of this diode is connected to the outlet. A current is fed to the positive inlet of the function amplifier 312 from the shutdown circuit 42 via a conductor 324, a resistor 326 connected to the cathode of the diode 322 and the resistor 320 when the control system delivers a brake release signal Operating voltage Z + limited by a diode 327, which lies between the diode 322 and the operating voltage Z + The current flows from the vehicle battery via the switch-off circuit 42 and a resistor 328, which lies between the battery voltage B + and the conductor 324. The conductor 324 is furthermore connected to the collector electrode of the transistor 266, so that when a braking signal is present and the transistor 266 is therefore conductive, the current flowing through the comparison circuit 54 and the conductor 324 is interrupted. The current to the comparison circuit through conductor 324 only flows.

if there is a signal to apply the brake at the outlet of the control system, i.e. a brake release signal is missing.

The values of the components are chosen so that in the absence of an outlet on the timer 50 of the positive ven inlet of the operational amplifier 312 fed Current from conductor 324 and resistor 320 in the presence of a brake apply signal is greater than the current at the negative inlet across the Resistance 316 and the sum of the currents at the positi ven input through resistor 318 and the diode 322 and resistor 320 when the outlet is high, the negative inlet flow through resistor 316 predominates. If the control system is excited for the first time and provides a signal to apply the brake, the

is output of operational amplifier 312 to a high Voltage switched by which the outlet is locked via the feedback via the resistors 318 and 320. This normally high outlet is with connected to transistor 268 by conductor 282 to to load the transistor 268 in the conductive state, so that the shutdown circuit 42 can cause the brake to be released when a brake release signal is present.

Function amplifier 312 in comparison circuit 54 goes from its normally high level to ground potential only switched when it receives a current from Timer 50 receives which is greater than the switching level of the comparison circuit 54, which is the difference between the feedback currents to the positive inlet of operational amplifier 312 and the bias current to negative inlet via resistor 316 The timer 50 is integrated to form a signal of this strength after a predetermined time after a fault has been sensed or after the brake has been released took place. When the outlet of the timer 50 reaches the order switching level of the comparison circuit 54, then the outlet of the functional amplifier 312 switched to ground potential and contains the Abschäiiäignai that blocks the transistor 268 in the shutdown circuit 42, whereby the brake release magnet 44 is de-energized and a release of the

Braking is inhibited. The switch-off signal is from Comparison circuit 54 supplied as long as the timer

50 above the switching level of the comparison circle 54 stays

The response of comparison circuit 54 to the end

that of the fault current and the subsequent decrease in the output of the timer 50 below the switching level of the comparison circuit depends on whether the control system delivers a brake release signal Condition of applied brakes, it causes an end

so the fault current and the consequent reduction in the output of the timer 50 below the toggle level of the comparison circuit 54 that this cancels the switch-off signal by setting its outlet back to the positive Voltage level is switched because the current is too the positive inlet of operational amplifier 312 from Shutdown circuit 42 but the conductor 324 is fed. However, if the fault current ends during ventilation of the brakes, no currents are fed to the positive inlet of the function amplifier 312 and the Bias current through resistor 316 maintains the output of the operational amplifier at ground potential The comparison circuit 54 is therefore kept locked and continues its switch-off signal. Thus, the switch-off circuit 42 cannot release the brake if one is present Initiate braking signal. When the brake release signal from the control system ends, the is deleted Switch-off signal due to the current flowing via conductor 324 to function amplifier 312. To this

25 26

The comparison circuit 54 causes the control system to be switched off in an unlocked manner for the duration of an error if this occurs with the brakes applied occurs and a locked downshift, provided that the error signal is present at least temporarily Brake release signal is available. The dynamic test circuit 58 includes two PNP transistors 330 and 332. The speed signal from the tachometer generator 22 is sent to the base electrode of the transistor 330 and the emitter electrode of the transistors 330 and 332 via a diode 334 and a resistor 336 connected. The speed signal from the tachometer generator 24 is connected to the base electrode of the transistor 332 and to the emitter electrodes of the transistors 330 and 332 via a diode 338 and resistor 340 connected.

The emitter electrodes are all connected to ground via a resistor 340.

The diodes 334 and 338 carry the maximum wheel speed signal! via a voltage divider from the. Resistors 336 and 340 too. Exceeds the higher wheel speed the lower wheel speed by a specified amount, for example corresponding to 27.4 km / h, so the transistor 330 or 332, to the base electrode of which the lower speed signal is fed, in switched to the conductive state and causes a current to the positive inlet of the brake cycle depth comparator 40 via a conductor 342, so that a brake release signal is generated and the brake release magnet 44 is excited. gnal to disable the control system. In this way, in the event of any failure of the speed sensor 14 or 16, the control system is switched off.

The triggering of a switch-off signal is made visible in order to notify the driver of the presence of the error. For this purpose, the error signal is fed to the base electrode of an NPN transistor 344 in the warning lamp circuit 56 via a resistor 346. The collector electrode of the transistor is connected to the base electrode of a Darlington transistor 348, the emitter electrode of which is connected to ground. The collector electrodes of the transistors 344 and 348 are connected to a lamp 350 via associated resistors 352 and 354, while the other side of the lamp is connected to the battery voltage B + switch, whereupon the lamp 350 is energized and visibly indicates the fault present

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For this purpose 4 sheets of drawings

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60

Claims (7)

Patent claims: 1. Electronic anti-lock control system for a pressure medium-actuated vehicle brake with at least one speed sensor that continuously issues a speed signal, to which a delay switch responds and generates a control signal when the change in the speed signal exceeds a predetermined threshold value indicating the risk of blocking, with devices that generate a delay reference signal form which, based on the speed signal, corresponds to a simulated vehicle deceleration, with devices that supply a wheel acceleration signal, with an integrator that is derived from the deceleration reference signal and the wheel acceleration signal Error signal generated that ends the brake pressure reduction when the error signal falls below a certain Weri fäih, with a solenoid valve built into the brake line which - as long as it is energized - remains in the "lowering the brake pressure" position, characterized in that a comparator (40) is provided, the output signal of which is sent to both the solenoid valve (44) and the device (32; 184, 186, 188) is supplied to form the delay reference signal, this device contains a circuit (174, 184, 200) which suppresses the delay reference signal for the duration of the output signal, at the output of the integrator (ϊ92, 198), the error consisting of several parts ^ ignal (brake cycle depth signal) is formed, the first part of which represents the amount by which the time integral of the delay reference signal exceeds the wheel speed signal, and the second part of which represents the integral of the wheel acceleration signal during the output signal, a circuit responsive to the end of the output signal (184 to 190 ) contains a capacitor (190) which the integrator (192,198) on a We rt, which would result from a continuous summation of the deceleration reference signal and the wheel acceleration signal, the comparator (40) emits its output signal during the duration of the control signal and during the period in which the error signal (braking cycle depth signal) exceeds its reference value. 2. Anti-lock control system according to claim 1, characterized in that the wheel acceleration signal and the deceleration reference signal are combined in a summing point (182) in which their algebraic sum is formed from which the integrator (192, 198) forms the braking cycle depth signal, that the means (184, 186, 188) for forming the delay reference signal consist of a voltage source (Z +), a series-connected resistor (186, 188) and a switch (184) between the voltage source and the summing point & q, a capacitor ( 190) is connected in parallel to the resistor and the switch is connected to the comparator (40) while the brake is being released and is switched to non-conductive when the brake is applied and the capacitor is charged when the brake is applied and via the resistor via the resistor when the brake is released is discharged speed matched to the delay reference signal, so that the summing point is a charge pulse at When the switch becomes conductive and the braking cycle depth signal is set at the outlet of the integrator to a value which is equal to its value which it would assume if the switch was permanently switched on to supply the delay reference signal. 3. Anti-blocking control system according to claim 1, characterized in that the braking cycle depth signal acting together with the control signal on the comparator (40) is assigned a first high threshold value which is greater than all braking cycle depth signals during the application of the brake, and a second lower threshold value during the release of the brake, so that the deceleration switch itself controls the release of the brake, and that the devices (178, 180) responsive to the speed signal in the brake cycle depth integrator (32) form an acceleration or deceleration signal, and the brake cycle depth signal when one of the deceleration switch disappears (30) supplied control signal lies below the second threshold value in a first range of friction coefficients of the roadway and the wheel load, so that the deceleration switch alone controls the braking cycle, in a second range of friction coefficient of the roadway and the wheel load one above the second threshold has a value so that the brake cycle depth integrator increases the duration of the release of the brake, the devices (184-190) responding to the reapplication of the brake adjusting the integrator (192, 198) so that the brake cycle depth signal that is formed receives a value that is equal to its value, which it would reach with continuous summation of the deceleration reference signal and the wheel acceleration signal, and which becomes greater than the second threshold value over a series of braking cycles when the mean value of the kid's deceleration exceeds the maximum vehicle deceleration by the time the vehicle was ventilated Brake to enlarge. 4. Anti-lock control system according to claim I _1, characterized in that the delay switch (30) responds to the speed signal and forms a control signal when the speed of the change in speed exceeds a predetermined threshold value indicating the risk of locking, and this clears when the wheel speed is a first Reference speed is equal, which decelerates with the speed of the predetermined threshold value of the deceleration, that a delay amplifier (34) supplies a first reference signal when the wheel deceleration exceeds a deceleration reference level which is lower than the predetermined deceleration threshold value and this clears when the wheel speed of a second Reference speed becomes the same, which has a delay equal to the delay of the delay reference signal, that an acceleration switch (36) responsive to the wheel speed supplies a second reference signal in the time in which the speed of the speed change is a given When the acceleration level is exceeded, devices (14-28, 246) responding to the wheel speed supply a third reference signal, the magnitude of which is matched to the wheel speed, so that a device (46) sums the respectively larger first or second reference signal with the third reference signal the braking cycle depth Reference signal to form that a brake air lock switch (38) supplies a BrcmslOftsperrsignal if there is no control signal or the wheel acceleration is below a predetermined lower level, which is the approach of the wheel speed to the driving speed represents that the comparator (40) delivers a brake release signal when the sum of the Brake cycle depth signal and the control signal is greater than the sum of the brake cycle depth reference signal and the brake release lock signal, wherein the brake release lock signal is greater than the maximum value of the Brake cycle depth signals and the control signal larger than the maximum value of the braking cycle depth reference signal, so that the delay switch itself causes the brake release signal, the brake cycle depth signal being the wheel speed change during the brake release signal indicating size, and that a control device (42, 44) on the brake release signal responds and causes the brake to be released during the brake release signal, wherein the delay switch the duration of the release of the brake in a first operating mode of the control system, the brake cycle depth integrator in a second mode of operation and the brake release lock switch controls in a third mode of operation. 5. Anti-lock control system according to one of claims 1 to 3, characterized in that Control circuits (30, 32, 38, 40, 42) respond to the speed signal and deliver a brake release signal, if the speed signal indicates a risk of locking, and a control device in response to the brake release signal (44) responds and the brake is released for the duration of the brake release signal, and that the control system a circle that detects an error (48,50,52) contains, which, depending on a sensed error, delivers an error signal to which a Brake release signal responsive logic circuit (54) responds and a switch-off signal for the control system supplies solely by the error signal, which is only deleted when the error signal! and the brake release signal end, with a device (268) responding to the switch-off signal and the response of the Control device for the brake prevents the brake release signal. 6. anti-lock control system according to claim 5, characterized in that the logic circuit is a Means (316) for forming a reference signal and a comparator (312) which contains the switch-off signal form that the comparator receives ei.ι feedback signal in the absence of the switch-off signal, whose size is smaller than the sum of the error signal and the reference signal, but larger? ls the reference signal is that devices (280, 44, 293) acting on the control device at Fehion of a brake release signal deliver a brake application signal whose size is smaller than the sum of the error signal and the reference signal, but is greater than the reference signal, that the comparator is based on the error signal, the reference signal, the feedback signal and the Bremsanlcgsignal respond and the switch-off signal at the time when the sum of the magnitudes of the error signal and the reference signal exceeds the size of the feedback signal or the brake application signal, so that the switch-off signal is formed solely by the error signal, but only ends when the error signal and Brake release signal end. 7. Anti-lock control system according to one of the Claims 1 to 3, characterized in that control circuits (30, 32, 38, 40, 42) respond to the speed signal respond and deliver a brake release signal when the speed signal indicates a risk of locking and a control device (44) responds to the brake release signal and the brake during the Duration of the brake release signal ventilates, the control system contains a fault-detecting circuit, which a timer circuit (50) and a plurality of devices (48, 50, 52) for forming error signals, which are sent to the timer, in which there is also a Signa! comes in, wherein the timer forms a main error signal of a predetermined magnitude when one of the Error signals or the signal indicating the brake release time exist for a predetermined time, with Means (316) for forming a reference signal and a comparator deliver a switch-off signal and the comparator receives a feedback signal in the absence of the switch-off signal, the size of which is smaller than the sum of the size of the main figure and the reference signal, but greater than the reference signal, that means responsive to the control circuits (280,44,293) deliver a brake application signal in the absence of a brake release signal, the size of which smaller than the sum of the magnitudes of the main fault signal and the reference signal, but larger than that The reference signal is that the comparator is based on the main error signal, the reference signal, the feedback signal and the brake application signal responds and then supplies a switch-off signal when the sum of the Size of the reference signal and the main error signal the size of the feedback signal or the Brake application signal exceeds, so that the switch-off signal is caused solely by the main error signal , but deleting it requires the end of the main error signal and the brake release signal, and that on the switch-off signal a device (? 68) responds and prevents the control device for the brake from responding to the brake release signal.