DE2742991A1 - BRAKE JACK PROTECTION CONTROL SYSTEM FOR WHEELED VEHICLES - Google Patents

Description

- li -

The invention relates to an anti-lock control system for wheeled vehicles with devices for generating a wheel speed signal to which a deceleration switch responds and forms a control signal when the speed of the change in the wheel speed is a predetermined, exceeds the threshold value indicating the risk of blocking.

Such a control system is for example

known from U.S. Patent 3,953,080. This control system enables an adaptation to the different driving conditions, so Driving on roadways with variable coefficients of friction with different Vehicle load. It is particularly suitable for heavy towing vehicles with air brakes.

The invention is based on the object

to further develop a brake anti-lock control system of the type mentioned at the outset so that its adaptability to different driving conditions is improved. |

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 sub-claims.

The inventive design is the Control system that allows you to work in three different ways of working, with the

-12-RO 98 1 3/099 1

Duration of brake release by the delay switch alone is controlled, thereby making for a heavily loaded vehicle and / or a high coefficient of friction of the road surface results in optimal braking behavior.

In a 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, whereby optimal braking conditions are created for medium loads and medium friction coefficients of the roadway.

Finally, in the third mode of operation, the braking duration is controlled by the brake air lock switch, whereby the control system for driving conditions with low vehicle load and / or low coefficient of friction of the roadway has the most favorable braking conditions.

The provided test circuits enable the control system to be switched off in the event of errors, whereby the control circuits are prevented from venting the travel mats, if there is no brake release signal or if the brake lift signal is present for longer than a specified time.

The invention is explained with reference to the accompanying drawings. In the drawings is

-13-

809813/0991

Figure 1 is a block diagram of a preferred embodiment a brake block protection control system according to the invention,

2a and 2b put together a schematic

Circuit diagram of the steeper system according to Fig. 1 and Fig. 3a, 3b, 3c and 3d diagrams, the three

possible modes of operation of the control system according to FIGS. 1 and 2 ereildutern.

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

In the preferred embodiment of the

The invention provides that each vehicle axle is monitored independently of the other axles, both the axles both the tractor and the trailer are monitored so that each axle has a complete anti-lock control system is equipped. The only thing the brake systems of the various axes have in common is one that can be actuated at will Air pressure source that supplies the braking systems. The control of all brakes on tandem axles could be modified in a modified way monitored by a single anti-lock control system

809813/0991

as well as other desired combinations can be used.

The control system according to the invention is based on the known principle of sensing a risk of blocking applied brakes, lowering the brake pressure for a specified time and then increasing the brake pressure, such braking cycles are repeated several times if necessary. The term used in the description below "Brake cycle depth" 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. 1 shows, the wheels 10 and 12 lying on opposite strings of the vehicle are of an axle Speed sensor 14 or 16 assigned. These are preferred designed as an electromagnetic transducer with variable reluctance and toothed rudders, the alternating current signals deliver, the frequency of which is proportional to the wheel speeds. These signals are fed to square-wave amplifiers 18 or 20, which form square wave signals, the frequency of which is equal to the frequency of the alternating current signals. The square wave signals of the square wave amplifiers 18 and 20 are supplied to associated tachometer generator circuits 22 and 24, respectively, the electrical analog signals

-15-

809813/0991

deliver the size of the speed of the wheels 10 and 12, respectively
is proportional. 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
a delay switch 30, a brake cycle depth integrator 32, a delay amplifier 3 ^, an acceleration switch 36, a brake release lock switch 38 and the
negative inlet of a brake cycle depth comparator Ao
forwarded.

The brake cycle depth comparator ^ O delivers a brake release signal when the size of the signals at its positive inlet exceeds the size of the signals occurring at the negative inlet. The brake release signal is fed to a disconnection circuit 42 which has a brake release magnet kh
energized, so that the brake is released while a brake release signal is being delivered.

The delay switch 30 supplies a control signal if the wheel deceleration exceeds a reference deceleration, which indicates a risk of blocking. The reference delay is approximately the maximum possible vehicle delay the same and depends on the wheel speed. In the exemplary embodiment is assumed that the reference delay, the one

-16-

80981 3/0991

Indicates the risk of locking, at a wheel speed of zero 0.9 g and at a wheel speed of 96 km / h corresponding to 1.3 g. The delay switch 30 terminates the control signal when the deviation of the wheel speed from the integral of the reference speed during the brake release approaches the value zero. That Control signal is fed to the positive inlet of 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 being a composite signal having a first part indicating 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 which is the integral of the wheel acceleration is during brake release. The delay reference signal for the brake cycle depth integrator 32 is approximately equal to the reference delay of the delay switch 30, so that the Brake cycle depth signal from brake cycle depth integrator 32 essentially represents the size of the speed change during brake release. In the exemplary embodiment it is assumed that this reference delay is 1.0g.

The brake air signal of the brake cycle depth comparison Ärs 40 deletes the reference delay in the brake cycle depth

-17-809813 / 0991

integrator 32 as long as it is available. If the brake release signal of the brake cycle depth comparator 40 ends, in order to reapply to cause the brake, the brake cycle depth signal set to a value that corresponds to the amount by which the time integral of the reference deceleration exceeds the wheel speed, during the time the brakes were applied and released. Is the mean wheel deceleration less than the reference delay, then the brake cycle depth signal set to zero. If the mean value of the wheel deceleration is greater than the reference deceleration, the braking cycle depth signal is set to an appropriate value as previously described.

The delay amplifier 34 supplies a brake cycle depth enbefehlssignal, the size of which is proportional to the delay until it is saturated at a predetermined delay level that is lower than the delay reference signal of the delay switch 30. In the exemplary embodiment, the delay amplifier 34 is saturated when the wheel deceleration reached about 0.8g. The delay amplifier 34 is designed so that the control signal of the delay switch 30 always returns to the low value before the output of the delay amplifier 34 switches to the low value. This ensures that the braking cycle depth

-18-80981 3/0991

Reference signal of the delay amplifier 34 lasts longer than the control signal of the delay switch 30. The brake cycle depth reference signal of the delay amplifier 34 enters an inlet of a grating 46.

The acceleration switch 36 delivers

Brake cycle depth reference signal when sensing a predetermined upper level of a wheel acceleration. In the exemplary embodiment, the acceleration switch 36 supplies this braking cycle depth reference signal at a wheel acceleration of approximately 2.0 g. The outlet of the accelerator switch 36 is fed to a second inlet of the grid 46, the outlet of which into the negative Inlet of the brake cycle depth comparator 40 is received. The grid 46 connects the larger Deceleration amplifier 34 braking cycle depth reference signal or the accelerator switch 36 with the negative inlet of the brake cycle depth comparator 40. The sum of this signal forms at the negative inlet of the brake cycle depth comparator 40 is a reference value associated with the brake cycle depth signal from Brake cycle depth integrator 32 is compared. In the working example the saturated outlet of the deceleration booster 34 corresponds to a braking cycle depth corresponding to 4.8 km / h and the outlet of the accelerator switch 36 in sensing

-19-

809813/0991

of the upper acceleration level also represents a braking cycle depth corresponding to 4.8 km / h. Furthermore, the wheel speed signal from the conductor 28 at the negative inlet of the Brake cycle depth comparator 40 a part of the reference signal, which corresponds to about 2.4 km / h for every 16.1 km / h driving speed, represent.

The brake release lock switch 38 is normally switched on and provides a brake release lock signal to the negative inlet of the brake cycle depth comparator 40. The brake release lock signal is cleared by a control signal supplied by the delay switch 30 or upon sensing a Acceleration that is greater than a predetermined lower acceleration level that is a function of the size of the braking cycle depth signal is dependent. In the exemplary embodiment, the brake air lock signal of the brake air lock switch disappears 38 when sensing an acceleration of 0.5g with a large zero of the braking cycle depth signal and with 0.1g with the largest Brake cycle depth signal. In the absence of a control signal and if the wheel acceleration falls below the specified lower acceleration level, the brake air lock signal occurs on the brake air lock switch.

The size of the brake air lock signal from the brake air lock switch 38 is greater than the maximum value of the braking

-20-

80981 3/0991

27A2991

cycle depth signal from brake cycle depth integrator 32. Es Thus, a BremsIUftsignal at the outlet of the braking cycle depth comparator 40 by the control signal of the delay switch 30 can only occur when the wheel deceleration exceeds the reference deceleration of the deceleration switch 30, which is the Indicates a risk of blocking. Furthermore, the size of the control signal from the delay switch 30 is greater than the largest brake cycle depth reference signal at the brake cycle depth comparator 40, so that the control signal delivers a brake release signal at any time and thus releases the brake while it is in existence caused.

After the brake is released by the control signal, the response of the control system changes as a function of the length and depth of the braking cycle determined by the braking cycle depth signal from the braking cycle depth integrator 32, the deceleration of the vehicle and the acceleration of the vehicle wheels is shown.

When the vehicle is heavily loaded and / or the road surface has a high coefficient of friction at which the braking cycle depth is short and flat, the control system works solely through the delay switch 30. In this mode of operation causes the control signal of the delay

-21-

809813/0991

switch 30 a reapplication of the brake. This mode of operation conditionally favorable conditions for this driving situation.

With an average coefficient of friction of the roadway and / or average load on the vehicle, the braking cycle depth is greater ,, The duration of the brake air signal is in this case from the brake cycle depth signal from brake cycle depth integrator 32 in conjunction with the brake cycle depth reference signal controlled at the negative inlet of the brake cycle depth comparator 40. In this mode of operation, the brake cycle depth signal is greater than the brake cycle depth reference signal at the negative inlet of the brake cycle depth comparator 40, if the control signal from the delay switch 30 ends and that The brake air signal remains until the brake cycle depth falls below the brake cycle depth reference signal. At this Operating mode, optimal braking conditions are achieved under these driving conditions.

If the vehicle is under low load and / or the road surface has a low coefficient of friction, the brake release lock switch is required 38 a third mode of operation, wherein the braking cycle depth signal from the Bramszyklustiefenintegrator 38 a release of the Brake is maintained until the brake air lock switch 38 calls for the brake to be reapplied, namely when the

-22-80981 3/0991

Wheel acceleration drops to a low value, which indicates that the wheel speed equals the driving speed approach. At this low acceleration level j, the brake air lock switch 38 supplies the brake air lock signal, to delete the brake release signal and to apply the brake again. This mode of operation is among the specified Driving conditions optimal braking behavior. The remaining parts of the control system shown in Fig. 1 are used Self-check to report errors in the control system and to switch off the control system if errors occur cause. '

For this purpose, a test circuit 48 is provided for the speed sensors IA and 16, which a timer 50 generates an error

signal when one of the circles of the speed sensor 14 and 16 is sensed as interrupted. Another mistake- j

i signal is supplied to timer 50 from power supply 52, for example the vehicle battery, if its voltage B + is below the operating voltage Z + of the control system sinks. The shutdown circuit 42 also provides an error signal to the timer 50 if in the excitation circuit of the magnet 44 An interruption or a ground fault occurs.

The timer provides its output at the trigger level to a comparator circuit 54 when either of the

-23-809813 / 0991

Error signals from the test circuit 48 longer than a predetermined one
Time is present or when the brake release magnet 44 is open
or earth fault or to release the brake for a time
remains energized beyond a predetermined time limit
which is a function of the brake cycle depth signal from
Brake cycle depth integrator 32 is.

The comparison circuit 54 then supplies a switch-off signal to the switch-off circuit 42 in order to de-energize the brake release magnet 44 and to end the brake release or to stop the brake release
Excitation of the brake release magnet and thus the release of the brake
to prevent. !

To prevent the control system from working incorrectly! if, due to a sensed error, the control system is prevented from releasing the vehicle brakes when a brake air signal is present, the comparison circuit 54 can be blocked, and \

depending on whether the control system requires ventilation or j

not calling. j

i The comparison circuit 54 receives a signal from '■

Shutdown circuit 42, which is the outlet of the control system. j If an error is detected and corrected by yourself while

the control system causes the brake to be applied, then there is

the hold signal of the comparison circuit 54 only as long as that
Error signal is present. However, the error signal is also present

-24-809813 / 099 1

only briefly at the same time as a brake air signal from the brake cycle depth comparator 40, the comparison circuit 54 supplies the switch-off signal for the longer-lasting signal. In this way, the brake release signal blocks the comparison circuit 5h in order to block the switch-off signal during its duration. When the switch-off signal disappears, the control system works again in the prescribed manner.

The error signal of the comparison circuit 5h is fed to a warning lamp circuit 56 in order to indicate the presence of an error to the driver.

For further testing of the speed sensors 14 and 16, a dynamic tester 50 is also provided, which the The wheel speeds of the tachometer generators 22 and 24 are monitored and an outlet is supplied to the brake cycle depth comparator 40, to cause the brake to be released when the speed of one wheel exceeds that of the other wheel by a specified value, which is selected in the exemplary embodiment corresponding to 27 km / h. The outlet of the tester 58 causes the brake release via the maximum time limit until the test circuit described above delivers a switch-off signal for the control system.

2a and 2b of the drawings show a more detailed circuit diagram of the control system according to FIG. 1.

-25-809813 / 0991

2742901

A regulated voltage source 52 supplies

a regulated operating voltage Z + for the control system. A 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 provides a regulated one Voltage shared with the base electrode of an NPN transistor is connected, the collector electrode of which is connected to the battery. The transistor 66 is loaded into the conductive state the regulated voltage Z +, which is the voltage at the cathode of the Zener diode 62 reduced by the voltage drop between Base electrode and emitter electrode in transistor 66 is the same ^ i The voltage Z + is tapped off at a resistor GB.

The remaining part of the voltage source 52 is used creating an error signal when the battery voltage is low B + is lower than the desired operating voltage Z + der Control system that is necessary for proper work. This error signal is generated by means of an NPN transistor 70 formed, whose emitter electrode is grounded and whose collector electrode is connected to the emitter electrode of transistor 66 a resistor 72 is connected. If the battery voltage B + is above the breakdown voltage of the Zener diode 62, then it is sufficient the voltage drop in resistor 64 is used to make the transistor conductive, so that the voltage at its collector

-26-

809813/099 1

electrode is close to ground potential. However, the battery voltage B + should be below the breakdown voltage of the Zener diode 62 decrease, the transistor 70 is blocked and the voltage at its collector electrode rises to about Battery voltage Bf to provide an error signal through a diode 73. This error signal is transmitted via a conductor 74 supplied to the timer 50.

The square wave amplifier 18 includes a resistor 76 in series with the output coil of the speed sensor 14 lies between the operating voltage Z + and ground. The alternating current outlet of the speed sensor 14, which is a measure for the speed of the vehicle wheel 10 is on one side of the vehicle axle, there is one with the positive inlet Function amplifier 78 connected via series resistors 82 and 82. The operating voltage Z + is at the connection point applied between resistors 80 and 82 via a capacitor 84 and to the positive inlet of the functional amplifier 7 * J via a resistor 86. A bias is provided at the negative inlet of the operational amplifier 78 through a voltage divider made of in series Resistors 88 and 90 between the operating voltage Z + and ground. A feedback resistor 92 is between

-27-

809813/0991

de «outlet of the functional amplifier 78 and its positive Admission provided.

The functional amplifier 78 and the rest

Functional amplifiers in the control system according to FIGS. 2a and 2b are current amplifiers, with the current at the positive inlet being subtracted from the current at the negative inlet and with a positive output when the current at the positive inlet exceeds the current at the negative inlet. Furthermore, the function amplifiers usually have a large outlet when no current is supplied to the inlets. The at-load current, which is fed through the voltage divider from the resistors 88 and 90 to the negative inlet of the functional amplifier 78, serves as a bias voltage for the outlet of the functional amplifier 78 at ground potential. The square-wave amplifier 18 responds to the alternating current signals of the speed sensor lh and supplies a square wave of the same frequency.

The square wave amplifier 20 includes resistors 9 ^, 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 square wave to deliver the same frequency as the alternating current signal that the speed sensor 16 according to the speed of the vehicle wheel 12 supplies.

-28-

8098 1 3/099 1

The square wave of the square amplifier 18

is fed to a differentiator circuit in the tachometer generator 22, which consists of a resistor 112 and a capacitor 114. A positive current pulse is applied to the positive inlet of a functional amplifier 116 via a diode 118 at each leading Edge of each square wave of the square wave amplifier 18 and a negative current pulse is fed to the negative inlet of the functional amplifier 116 via a diode 120 at each trailing edge of each square wave of the square wave amplifier 18 forwarded. The negative inlet of the function amplifier 116 is connected to ground via a capacitor 122. A feedback capacitor 124 lies between the outlet of the operational amplifier 116 and its negative inlet, around an integrator to create its integration through a feedback resistor 126 is determined, which is parallel to the capacitor 124. The outlet of the operational amplifier 116 is a Analog voltage that is directly proportional to the speed of the vehicle wheel 10.

The tachometer generator 24 includes resistors 128 and 130, capacitors 132, 134 and 136, diodes 138 and 140 and a function amplifier 142, which in the same way as the function amplifier in the tachometer generator circuit is 22 switched

-29-

809813/0991

274299

is. The output of the tachometer generator 24 is an analog voltage a strength that is directly proportional to the speed of the vehicle wheel 12.

The speed selector 26 responds to the wheel speed signals of the tachometer generator circuits 22 and 24 and provides a wheel speed signal on conductor 28 corresponding to the lower speed of vehicle wheels 10 or 12. The speed selector 26 includes PNP transistors 144 and 146, their collector electrodes are connected to ground and their emitter electrodes are connected to the regulated operating voltage 7+ via a resistor 148 lie. 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 to the base electrode of the transistor 146. The outlet of the speed selector 26 to the Conductor 28 is the speed signal of the tachometer generator 22 or 24 plus the voltage drop in the base-emitter path of the each conducting transistor 144 or 146.

The delay switch 30 includes a filter resistor 150, which is in series with a capacitor 152 between the conductor 28 carrying the wheel speed signal and a summing point 154 is connected. The inlet to summing point 154 from capacitor 152 is a stream whose

-30-

13/0991

Strength represents the wheel acceleration. This acceleration signal is combined at summing point 154 with a stream whose Large a reference delay corresponding to the maximum vehicle deceleration is. This delay reference signal consists of two parts. The first part is a constant current to the Summing point 154, from the operating voltage Z + via a Resistor 156 is fed, while a second part is a current, the strength of which is proportional to the wheel speed and the buzzer point 154 from the conductor 28 via a resistor 158

at

is forwarded. The delay reference signal shown at summing point 154 corresponds to a wheel deceleration of 0.9g at zero wheel speed and increases to 1.3g for one 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 fed to the negative inlet of a functional amplifier via resistor 162 and diode 164. Between the anode of the diode 164 and the outlet of the functional amplifier 160 there is a diode 166 to set a speed threshold, inserted through diode 164. The positive inlet of the operational amplifier 160 is grounded.

-31-

809813/0991

2 7 Λ 2 9 y

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

In the absence of a wheel deceleration and for wheel decelerations that are smaller than the reference deceleration, it is sufficient the delay reference signal applied to summing point 154 the resistors 156 and 158 is fed and connected to the negative inlet of the function amplifier 160, to bring the function amplifier to ground potential at the outlet. During wheel decelerations, the capacitor is used 152 Current subtracted from summing point 154, where the portion is a function of the amount of wheel deceleration. Is the wheel deceleration such that the current flows through the capacitor 152 equals the delay reference current, in which case a risk of blocking is indicated, the outlet of the functional amplifier 160 switches to a positive voltage, the contains the control signal from delay switch 30. Resistor 162 determines a wheel speed change that is required is before the negative inlet of the operational amplifier 160 can be reduced to zero in order to control the signal cause.

-32-

80981 3/099 1

27A2991

The control signal is transmitted via a diode 170

the brake release lock circuit 38 supplied to the brake release lock signal to end. For this purpose, it is fed to the brake cycle depth comparator AO via a diode 172 for ventilation to effect the brake.

As a result of the delays 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 the threshold value of the Reference delay corresponds to. 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 at the threshold value of the delay to manufacture. The decreased voltage at summing point 154 represents the size of the deviation of the wheel speed from one The deceleration reference speed approximately corresponds to the threshold value. If the wheel deceleration ends and the wheel begins again To accelerate, the voltage at summing point 154 increases in accordance with the approximation of the deviation of the wheel speed from Time integral of the reference delay at zero at which point in time the current to the negative inlet of the function amplifier 160 is fed to terminate the control signal.

-33-

809813/099 1

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

The brake cycle depth integrator 32 includes one Filter resistor 178 in series with a differentiating one Capacitor 180 between conductor 28 carrying the wheel speed signal and a summing point 182. The inlet of summing point 182 from capacitor 180 is a current one Strength according to the wheel acceleration. This acceleration signal is optionally at summing point 182 with a current which represents a reference delay of 1.0g which is approximately equal to the reference delay of the delay switch 30 and also represents the maximum possible vehicle deceleration. The reference delay current is optionally set by a PNP transistor 184 and resistors 186 and 188 supplied, the between the summing point 182 and the operating voltage Z +. A capacitor 190 is in parallel with resistor 188.

The reference delay factor becomes the summing point 182 fed through transistor 184 when it is conductive.

The sum of the vehicle acceleration signal and the deceleration reference signal becomes the negative inlet of a functional amplifier 192 via a diode 194.

-34-

809813/099 1

The positive inlet of operational amplifier 192 is ground. A diode 196 is provided between the anode of the diode 194 and the outlet of the function amplifier 192 in order to transmit the through remove the diode 194 given speed threshold. The operational amplifier 192 has a feedback capacitor 1Q8 between its outlet and summing point 182 to form an integrator.

The outlet of the operational amplifier 192 is

normally held at ground potential by the delay reference current applied to summing point 102. However, if the current flowing through the capacitor from summing point 182 as a result of wheel deceleration changes the current to the Exceeds summing point 182 via transistor 184, the output of the function amplifier becomes the brake cycle depth signal. This is the integral of the summation of the currents until the integral reaches zero or ground potential, 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 controlled, the one with the base electrode of the transistor is connected via a resistor 200. In the absence of a brake release signal, the outlet of the brake cycle depth comparator has

-35-

809813/0991

2742931

40 is ground potential and transistor 184 is conductively polarized in order to conduct the delay reference current to summing point 182. When a brake release signal occurs, the transistor is blocked, so that the brake cycle depth integrator only integrates the wheel acceleration signal and feeds it to summing point 182 via resistor 180. The brake cycle depth signal is thus a composite signal, the first part of which represents the V / ert by which the time integral of the delay reference signal the wheel speed exceeds while the brake is being applied and its second part is the integral of Wheel acceleration during brake release is, where the composite signal has a lower limit of integration of zero.

Since the delay reference signal provided to summing point 182 via transistor 184 is approximately the The delay reference signal of the delay switch 30, which is fed to the summing point 154, corresponds to that Brake cycle depth signal of the brake cycle depth integrator a Large, which is essentially the size of the change in wheel speed which occurs while the brake release signal is present. This is used by the brake cycle depth comparator 40 supplied so that the magnitude of the braking cycle depth signal

-36-

8098 13/099 1

274299

of the Breins cycle depth integrator is actually a measure of The size of the changes in wheel speed that occurs during the duration of the brake air signal. The Brees Cycle Depth Signal is connected to the positive inlet of the functional amplifier of the brake cycle depth comparator 40 via a resistor forwarded.

During brake release the transistor is blocked and the capacitor 190 discharges through the resistor 188. The rate of discharge of the capacitor 190 is related to the Vörzöjjerungs reference current to the summing point 182, while the transistor 184 is conductive, so that at the ends of the brake release signal and that from it After transistor 184 becomes conductive, a current surge occurs through resistor 186, which results from the recharging of capacitor 190 and has a strength and duration that sets the strength of the braking cycle depth signal of the braking cycle depth integrator to a value that corresponds to the braking cycle depth signal that it would assume when the reference delay signal would be continuously fed to the summing junction 182 through transistor 184, _E is the average wheel deceleration is smaller than the through resistors 186 and 188 supplied Verzögerungßbezugssignal initiated, the brake cycle of depth signal is Bremszyklus-

-37-

809813/0991

27429 ^ 1

deep integrators returned to ground potential, Exceeds however, the mean value of the wheel deceleration is the deceleration reference signal supplied via resistors 186 and 18 (3, so the braking cycle is deep ensignal on the previously mentioned Value set. Continuous wheel deceleration below that The reference delay signal causes a progressive increase the level to which the brake cycle depth signal is reset will. This is reflected in the increased current to the positive inlet of the function amplifier 174 via the Resistor 202 again.

The delay amplifier 34 includes one

Functional amplifier 204, the positive inlet of which is grounded. A filter resistor 206 and a differentiating capacitor 208 are connected in series between the conductor 28 carrying the wheel speed signal and a summing point 210. Of the Current through capacitor 208 represents the wheel acceleration. This signal is fed to the negative inlet of function amplifier 204 via diode 212. Between the Outlet of operational amplifier 204 and summing point 210 is a feedback filter capacitor 214, to which in parallel a resistor 216 is connected.

The delay amplifier 34 provides a first one Part of a braking cycle depth reference signal that represents one of the driving

-38-80981 3/0991

tool delay has a projected height until the at a given Delay level, which in the exemplary embodiment O.iJg cheats, is satiated. Then it causes a further wheel deceleration a drop in the voltage at summing point 210 while the current tries through resistor 216 to summing point 210, restore the tension to the level of about 0.8g. The voltage at the summing point 210 then represents the deviation of the ftad speed from a reference speed, which changes accordingly the delay represented by the feedback through the resistor. The wheel begins to close accelerate and the voltage at summing point 210 increases in accordance with the approximation of the deviation in wheel speed towards zero, the outlet of the functional amplifier 204 again drops to ground potential. The first part of the Bremszyklustief enverbindssigna Ls from the deceleration amplifier 34 in the steady state in the exemplary embodiment is a value corresponding to 4.8 km / h.

The delay amplifier 34 is designed in such a way that the control signal supplied by the delay switch 30 is always terminated before the outlet of the delay amplifier a jk goes out of saturation in order to ensure that the first part of the braking cycle depth reference signal of the delay amplifier 34>

-39-

80981 3/099 1

27-2991

is at the 4.8 km / h level when the deceleration switch 30 terminates the control signal.

The accelerator switch 36 includes one

Filter resistor 218, which is in series with a differentiating capacitor 220 between a summing point 221 and a
Filter 224 is located, which feeds a signal representing the wheel speed. The filter 224 consists of a resistor 226 and a capacitor 22fi connected in series thereto, which are connected between the conductor 28 and ground. The voltage on 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 between the
Summing point 221 and ground switched. The summing point 221 is connected to the base electrode via a resistor 232
PNP transistor 230 connected, 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 one
At the inlet of the functional amplifier 234, operating voltage Z + is fed in via a resistor 238.

The base of transistor 230 is grounded through resistors 222 and 232 and is normally

-40-

R09813 / 0991

-AO-

conductive. The outlet flow from the summing point 221 via the resistor 222 has a magnitude which represents a wheel reference acceleration which, in the exemplary embodiment, is 2.0 g. This acceleration reference signal is combined at summing point 221 with the wheel acceleration signal that comes from differentiating capacitor 220. 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 keep transistor 230 conducting. During the times of the wheel acceleration, the capacitor 220 supplies current to the summing point 221 in a magnitude 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 functional amplifier 234 acts as a current and voltage amplifier and also effects a phase reversal so that its outlet has a high level for accelerations above xmw ± 2.0g. This high level of the accelerator switch 36 contains a second part of the braking cycle

-Al-

809813/0991

2742yyι

-Altief en reference signal, for example corresponding to a Braking cycle depth is selected according to 4.8 km / h.

The two parts of the braking cycle depth reference signal the deceleration amplifier 34 and the acceleration switch 36 are with the anodes 240 and 242 in the grid 46, respectively tied together. The cathodes of diodes 240 and 242 are connected to the negative inlet of the function amplifier 174 in the üremszyklustiefen comparator 40 connected through a resistor 244. The diodes 240 and 242 cause a coupling of the respective higher part of the Breras cycle depth reference signal with the functional amplifier 174.

The wheel speed signal in conductor 28 goes into the

negative inlet of the function amplifier 174 of the braking cycle depth comparator via a resistor 246. The power inlet to function amplifier 174 through 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 end Brake cycle depth reference signal composed of these three parts is compared with the braking cycle depth, which is determined by the size of the braking cycle depth signal of the braking cycle depth integrator 32 is shown in order to determine the duration of the brake release in detail and thus the operation of the Control system.

-42-8098 13/099 1

The Brera air lock circuit 30 contains a filter resistor 245 and a differentiating capacitor 247 lying in series with it, which lies between the outlet of the filter 224 and the negative inlet of a function amplifier 24b. Capacitor 247 provides an acceleration signal to the negative inlet of functional amplifier 248. A feedback filter capacitor 250 is provided between the outlet of functional amplifier 240 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 function amplifier 248 via a resistor 252. A second part of the acceleration reference signal is a current with a strength proportional to the braking cycle depth, which is fed to the negative inlet of the functional 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 240 represents the wheel speed which is approaching the vehicle speed and can be, for example, a wheel acceleration of 0.5g with a braking cycle depth of zero _# which decreases to 0.1g when the braking cycle depth has a maximum value.

-43-809813 / 099 1

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

The brake release inhibit 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 inlet of the Function amplifier 248 is connected via a resistor 260. The brake release lock signal becomes effective again when it ends of the control signal and when the wheel acceleration decreases to the low reference acceleration value, which is at Approach of the wheel speed to the driving speed results.

Except for the elements already mentioned

the brake cycle depth comparator 40 includes a resistor 262 between the regulated operating voltage Z + and the positive inlet of the functional amplifier 174 in order to reduce the throughput by the Voltage drop in the emitter-base path of the transistors 144 and 146 in the speed selector 26 introduced bias voltage remove. A feedback resistor 264 is located between the

-44-

8098 13/099 1

-4A-

positive inlet and the outlet of the function amplifier 174 ^,!

whereby a feedback current j during a brake release signal

takes place, which the third part of the brake cycle depth reference j signals is the same and is proportional to the wheel speed if the wheel speed is 40 km / h, for example.

Resistors 176, 202, 244 and 246 and 258

are dimensioned so that the current j fed to the negative inlet of the function amplifier 174 through the resistor 258 during a brake release lock signal from the brake release lock circuit! 38 is larger than the positive inlet via the resistor 202 supplied conducted current at maximum values of the braking cycle low signal from the brake cycle low integrator 32. Further, the current to the positive inlet through the resistor 176 i during a control signal from the delay switch large ', as the maximum total braking cycle depth reference signal is fed to the negative inlet via resistors 244 and 246. The brake cycle depth integrator 32 is therefore incapable of causing the brake to be released and the delay switch 30 itself is effective in order to cause the brake release signal and the resulting release of the brake when the risk of locking is sensed. It also has the effect of keeping the brakes released as long as the control signal is present. Likewise can

-45-

809813/0991

the brake release lock signal of the brake release lock circuit 38 always request that the brake be applied.

The shutdown circuit 34 contains a Darlington transistor 266, which is controlled by the brake release signal, and a Darlington transistor 268 which causes the control system to be switched off and the brake to be released prevents certain errors in the system. Transistors 266 and 268 are in series with the vehicle battery Voltage B + connected to one another via a resistor 270, a resistor 272 and a resistor 274. The emitter electrode of transistor 266 is connected to the base electrode of an NPN transistor 276, the emitter electrode of which is on Ground and whose collector electrode is connected to one side of the brake release magnet 44. The connection between 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 + is and its collector electrode is connected to the other side of the brake air magnet 44. A Resistor 280 is between the emitter electrode and the collector electrode of transistor 278.

The turn-off transistor 268 normally receives a positive voltage from a conductor 202 and a Widdr-

-46-

809813/0991

stood 284 by the audit committee in the absence of errors the plant. 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 • a resistor 286 connected. The brake release signal causes a load on the transistor 266 in the conductive state, which in turn turns the transistor 276 on is to bring ground potential to one side of the brake release magnet 44. At the same time the current works through the resistors 270 and 272 bias the transistor 278 to make it conductive, so that the battery voltage B + reaches the other side of the brake release magnet 44, which is thus energized to release the vehicle brake during the To cause the existence of the brake air signal from the brake cycle depth comparator 40. When the brake release signal ends, the Transistor 266 blocked, so that the brake release magnet 44 is de-energized 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 is illustrated with reference to FIG 3a to 3d explained, the three different Operating modes are shown. In each of Figs. 3a to 3d

-47-80981 3/0991

the curve A represents the size of the wheel speed of the, which changes after releasing the wheel brakes. It also represents the brake cycle depth which is determined by the brake cycle depth integrator 32 is delivered. Curve B is a reference wheel speed that changes according to the reference deceleration in the deceleration switch 30 decreased. Curve C is a reference wheel speed which varies according to the reference delay in the deceleration amplifier 34 decreased and curve D is the braking cycle depth, those to the brake cycle depth comparator 40 from the deceleration booster 34, the acceleration switch 36 and from the conductor 28 is forwarded.

The control system starts braking the

Control the vehicle when the brakes are applied and the wheel deceleration the reference deceleration of the deceleration switch Exceeds 30. The control system has three modes of operation to ensure optimal braking behavior with different To enable vehicle loads and different coefficients of friction of the roadway. In all three modes of operation the delay switch 30 itself is effective to release the brake to cause when the wheel deceleration exceeds the reference deceleration caused by it, thereby increasing the risk of locking is shown.

-48-

809813/0991

In the first mode of operation, the duration of the brake release is controlled solely by the delay switch 30. This mode of operation is generally carried out 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 the Brake release is flat and short. These relationships are shown in Fig. 3a. At time t, the wheel deceleration exceeds the reference delay, so the delay switch 30 supplies the control signal to the brake release locking circuit 38 in order to the brake release lock signal to Bfcchen, and also to the brake cycle depth en comparator 40, which supplies a brake release signal to the Brake air solenoid 44 to excite. As a result of the delays in the brake system, the brake pressure increases after the Brake release magnet 44 is still on, so that a deceleration of the wheel is below that given by the deceleration switch 30 Purchase delay takes place. 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 the time t « the wheel deceleration ends as a result of the decreasing brake pressure, which results when the brakes are released, and the wheel begins to move to accelerate again to the driving speed. At time t, the braking cycle depth decreases to below the braking cycle depth reference values (Curve D). However, the Brwnsluftsignal remains

-49-

80981 3/0991

obtained at the outlet of the brake cycle depth comparator 40, since the control signal is still activated by the delay switch 30. At time t, 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. At this time, the brake cycle depth reference signal exceeds the brake cycle depth and the end of the control signal from the delay switch 30 causes the brake release signal to end at the outlet of the brake cycle depth comparator 40, causing the brakes to be reapplied the wheel deceleration is smaller than the reference deceleration in the braking cycle depth integrator 32. The wheel acceleration then ends and the deceleration of the wheel begins depending on the increasing brake pressure g comes to a standstill or the vehicle brakes are released by the driver or other road surface characteristics or loads occur, which changes the operation of the control system. This mode of operation, in which the delay switch 30 controls the duration of the brake fan, results in optimal braking behavior under heavy loads

809813/0 991

27A2991

of the vehicle and / or a large heating coefficient of the roadway.

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 is greater and longer than in the first mode of operation during braking. Reference is made to FIGS. 3b and 3c. At time t, the wheel deceleration exceeds the reference deceleration, indicating the risk of locking and the deceleration switch 30 supplies the control signal to clear the brake lift lock signal and to cause the brake lift signal, as is the case with the first operating mode ict. When the vehicle brakes are released, the wheels continue to decelerate, as indicated by curve A of the braking cycle depth, as a result of the decelerations in the brake 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 ^ eLt t is the drill cycle depth (curve A) greater than the reference braking cycle depth (curve D). At the time

-51-

8098 13/099 1

The wheel deceleration ends at point t and the wheel begins to move

2
to accelerate towards the driving speed as the braking forces decrease. In FIG. 3b, the wheel reaches a maximum acceleration of less than 2g, which is given by the acceleration switch 36 as the reference acceleration, and in FIG. 3c, a maximum wheel acceleration greater than 2g is achieved. At time t the deviation of the

Wheel speed from the reference speed (curve B) according to the influence of the delay switch 30 to zero and the delay switch 30 cancels the control signal. However, at time t, the braking cycle depth is still greater than the reference braking cycle depth (curve D), which is determined by the wheel speed, the deceleration amplifier ~ $ h in FIG. 3b and the acceleration switch 36 in FIG is maintained.

According to FIG. 3b, the size of the brake cycle depth decreases to below the reference brake cycle depth at time t ^, whereby the brake release signal of the brake cycle depth comparator UO ends and the brake is reapplied. According to F, -ig. 3c, the deviation of the wheel speed from the reference speed (curve C) at time t is reduced to zero, with the outlet of the deceleration amplifier

-52-809813 / 0 991

34 reduced to ground potential. However, the accelerator switch delivers 36 continues its share of the braking cycle depth reference signal through the grid 46 depending on the wheel acceleration, which exceeds 2g. The brake cycle depth reference signal and the brake release signal thus remain unchanged is maintained by the brake cycle depth comparator 40. At time t, - in Fig. 3c, the braking cycle depth decreases to below the reference brake cycle depth from the time at which the brake release signal is canceled in order to re-apply the brake cause.

When the brake release signal according to FIGS. 3b and 3c is deleted, the brake cycle depth signal is at ground potential reset, it being assumed that the mean value of the wheel deceleration is smaller than the reference deceleration im Brake cycle depth integrator 32 is. After that, the bike will continue to accelerate for a while and then start again to decelerate due to the applied brakes. This braking cycle is repeated several times, if necessary, until the vehicle comes to a standstill or the vehicle brakes are released by the driver or other surface properties of the Road surface or the load on the vehicle

-53-

809813/0991

cause the control system to work differently. 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 Obtain braking conditions by controlling the duration of the brake release by the brake cycle depth integrator.

In Fig. 3d, the third mode of operation is

Control system illustrated in which the duration of the brake release is controlled by the brake release locking circuit 38. This way of working is suitable for a low coefficient of friction on the road surface and / or light vehicle loads where the braking cycle depth when the brakes are released it becomes deeper and longer than in the two above-mentioned working methods. As with these, this will be The brake is released at time t when the wheel deceleration exceeds the reference deceleration of the deceleration switch 30, by the delay switch 30 providing the control signal. This clears the brake release lock signal and generates the brake release signal. At time t, exceeds the braking cycle depth (curve A) the reference value of the braking cycle depth (curve D). The wheel deceleration ends at time t ~ and the wheel begins to accelerate as a result of the decreasing braking forces. Because of the low coefficient of friction of the roadway

-54-80981 3/099 1

and / or the low vehicle load remains the wheel acceleration however, below the reference value of 2g given by the acceleration switch 36 is greater as the reference acceleration given by the brake release lock circuit 38. At time t, there is the deviation the wheel speed from the reference speed (curve B) accordingly the delay switch 30 is reduced to zero, whereupon the delay switch 30 cancels the control signal. However is the braking cycle depth is still greater than the reference braking cycle depth generated by the wheel speed signal and the deceleration amplifier 34 is given, so that the brake release signal ■ is maintained by the brake cycle depth comparator 40 remain. At time t, the deviation of the wheel speed from the reference speed (curve C) is reduced to zero and the The outlet of the delay amplifier 34 is lowered to ground potential. This increases the braking cycle depth reference signal decreases a value determined by the wheel speed signal when the wheel inclination is less than the reference acceleration of 2g set by the acceleration switch 36; is given is. The braking cycle depth remains greater than this low reference value, so that the brake release i signal from brake cycle depth comparator 40 is maintained

-55-

809813/0991

At the point in time te, the wheel acceleration falls below the reference acceleration given by the brake release lock circuit 38 which indicates the approach of the wheel speed to the driving speed. The brake release lock signal is therefore fed to the brake cycle depth comparator 40, whereby the The brake release signal is deleted and the brake is applied again.

When the vehicle is lightly loaded and / or the road surface has a low coefficient of friction, this results in 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, transistor 184 in brake cycle depth integrator 32 is in the time in which the brake release signal exists, blocked. During this time, the capacitor 190, which was previously through the resistor; 188 has been charged, through resistor 188 to an extent corresponding to the reference delay when transistor 184 is conductive. When the brake release signal is deleted, the transistor 184 conductive again and the resulting current pulse to the negative inlet of the function amplifier 192 is such that the capacitor 190 is charged and the braking depth signal is adjusted to the value it would have reached,

-56-809813 / 099 1

when the transistor 184 is continuously switched to the conductive state j

would have been and the reference deceleration j supplied by it is progressively summed up with the wheel acceleration signal; would have been. If the mean value of the wheel deceleration is less than the reference deceleration supplied when transistor 184 is conductive, the braking cycle depth signal is set to ground potential, when one of the brake release signals ends. However, if the mean value of the wheel deceleration is greater than that of the

Transistor 184 applied value of the reference delay, which the ' indicates the maximum possible vehicle deceleration, the braking cycle depth signal is set to a positive level, which is equal to the cone it would have reached if the reference deceleration were continuous with the vehicle acceleration signal was added while the brake lift signal is present. If the mean value of the wheel deceleration remains above the reference i Delay level, the brake cycle depth signal is progressively adjusted to a higher level until during a brake release the outlet of the brake cycle depth integrator has a value greater than the reference brake cycle depth signal fed in via resistors 244 and 246 in order to avoid the brake lift signal after the end of the control signal of the delay switch 30 to maintain so that the wheel speed can approach the driving speed. This requirement can

-57-809813 / 0991

for example, be provided when the vehicle brakes j by the driver to a lane small coefficient of friction only eanft are applied, so that the braking cycle depth similar to \ during braking on a road surface with a high coefficient of friction extends and thus the control unit operates in the first mode of operation. Reached the Bremszyklusttefensignal sufficient Grosse, \ to release the brake after the expiry of the control signal to maintain, so the re-application of the brakes is | generally controlled in accordance with the third mode of operation, so that the wheel speed can again increase to near the driving speed. 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 on the test circuits for switching off the control system directed, in the case of detected errors in the control system applying the brake and preventing the Air release of the brake is provided.

The timer 50 has a power inlet to the

negative inlet of the functional amplifier 288 from the outlet of the shutdown circuit 42 via a conductor 293, a diode 29 ^ »and a resistor 296. This current comes through the switch-off

-5a-

80981 3/0991

circuit 42 from the vehicle battery via the resistor 280 and the brake air magnet 44 when the transistor 276 is blocked, provided that the brake magnet 44 is not working properly due to a short circuit or an interruption. This Stroa, which is insufficient to excite the brake air magnet, is greater than the pre-tensioning at amplifier 288 via resistor 292 in timer 50, 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 inlet of amplifier 288 at an amount proportional to the brake cycle depth signal when the control system is operating. This current is fed through the brake cycle depth integrator 32 via a conductor 298, a resistor 300 and the resistor 296 .

When causing a BremslUftens, wherein the transistor is turned on 276, or interruption of the circuit or a ground fault of the Bremslüftmagneten the current ends to the timer 50 through the conductor 293 and the outlet of the verse türkers? 8ö begins positively to integrate due to the stream, df ? r flows through the resistor 292, in function of the current through the conductor 298, which the

-59-

80981.3 / 0991

BREESCYCLE DEPTH. The outlet of the timer is integrated bie to the trigger level of the comparison circuit 54, this time being based on an excessively long brake release is, which becomes greater as the braking cycle depth increases. At the The timer integrates backwards until the end of the brake release or the elimination of the fault on the brake lift agent 44 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 the speed sensor 14 and 16 monitored.

The test circuit 48 contains an NPN transistor 302, whose collector electrode is connected through a resistor 30A of the battery voltage B + and its emitter electrode to the positive inlet of the operational amplifier 288 of the timer 50 is connected. The non-grounded side of each of the speed sensors 14 and 16 is with the base electrode of transistor 302 through associated resistors 308 and 308. A filter capacitor 310 lies between the base electrode of transistor 302 to ground.

The base electrode of transistor 302 is normally close to ground above the low Impedance of the speed sensors 14 and 16. Are the

-60-80981 3/0991

Speed sensors 14 and 16 in the error-free state is therefore the Transistor 302 blocked. Should an interruption of the circuit occur in one or both of the speed sensors 14 and 16, the voltage at the base electrode of transistor 302 is increased by the supplied operating voltage Z +, which is fed in via resistors 76 and / or 94 and resistors and / or 308. This tension is enough to to switch transistor 302 conductive, so that a fault-indicating current to the positive inlet of the functional amplifier 288 in timer 50 is supplied. This current, combined with the bias current through resistor 292, always exceeds the current flowing to the negative inlet of the operational amplifier 288, so that the outlet of the operational amplifier positively integrated and the switching point of the comparison circuit 54 is reached after a predetermined time. Ends of the error signal B. causes the timer 50 to go down towards on Integrated ground potential.

The leakage current received from the regulated power source to the positive inlet of amplifier 288 through the Conductor 74 is fed when the battery voltage drops below B + the regulated operating voltage Z + falls has already been described. This fault current acts in the same way as the

-61- 809813/0991

Fault current for failure of the speed sensor and causes j

i the outlet of the function amplifier 288 is integrated in the positive sense i and after a predetermined time the switchover point
of the comparison circle 54 is reached. Increases the battery voltage [B + again and exceeds the operating voltage + Z i, so the fault current and the outlet ends' of the timer 50 integrates

again · downwards in the direction of ground potential.

The outlet of the timer 50 is connected to the |

negative inlet of a functional amplifier 312 of the comparison circuit 54 connected through a resistor 314 A bias i current is fed to the negative inlet via a resistor 316 j, which is between the operating voltage Z + and the nega-! tive inlet. A first knockback resistor 318; lies between the outlet of the function amplifier 312 and!

ti !

its positive inlet, while a second feedback

resistance 320 between the outlet and the positive inlet
across a diode 322. The application of this diode is with the
Outlet connected. A stream becomes the positive inlet of the
Function amplifier 312 from the shutdown circuit 42 via a
Conductor 324, one connected to the cathode of diode 322
Resistor 326 and resistor 320 fed when the
Control system delivers a brake release signal. The tension on

-62-809813 / 0991

the cathode of the diode 322 is limited to the regulated operating voltage Z + by a diode 327, which is between the Diode 322 and the operating voltage Z + is located. The current flows j from the vehicle battery via the shutdown circuit 42 and a Resistor 328 connected between battery voltage B + and conductor 324. The conductor 324 is also connected to the collector electrode of the transistor 266 so that when present of a brake release signal and therefore conductive transistor 266, which is connected to conductor 324 by comparison circuit 54 Deasuring current is interrupted. The current to the comparison circuit through the conductor 324 therefore only flows when at the outlet the control system has a signal to apply the brake, i.e. a brake air signal is missing.

The values of the components are chosen so that, in the absence of an outlet on the timer 50, the j Inlet of operational amplifier 312 supplied power from ■ Conductor 324 and resistor 320 when there is a signal to apply the brake is greater than the current on the negative Inlet through resistor 316 and the sum of the currents

at the positive input via resistor 318 and diode 322 j j and resistor 320 at high outlet the current at the negative: inlet through resistor 316 predominates. Will the control system

j

; -63-

! 809813/0991

energized for the first time and provides a signal to apply the Brake, the outlet of the function amplifier 312 is switched to a high voltage, through which the outlet over the feedback via resistors 318 and 320 is locked. This normally high outlet is with the transistor 268 connected by conductor 282 to load transistor 268 into the conductive state, so that the shutdown circuit 42 can cause the brake to be released when a brake release signal is present.

J-I

The functional amplifier 312 in the comparison circuit is from its normally high level to Mas ^ potential only switched when it receives a current from the timer 50 which is greater than the switching level of the comparison circuit 54, the ibtizk the difference between the feedback currents to the positive inlet of the operational amplifier 312 and the bias current to the negative inlet via the resistor 316 is. The timer 50 integrates to form a signal of this strength after a predetermined time after a Fault has been sensed or the brake has been released. When the outlet of the timer 50 reaches the switching level of the Comparison circuit 54, the outlet of the functional amplifier 312 is switched to ground potential and contains the

-64-809813 / 0991

Shutdown signal that the transistor 268 in the shutdown circuit 42
blocks, whereby the brake release magnet 44 is de-energized
and the brakes are not released. The switch-off signal 'is supplied by the comparison circuit 54 as long as the time!

i encoder 50 above the switching level of the comparison circuit 54 j

remain. j

The response of the comparative crisis 54

the end of the fault current and the subsequent decrease in the output of the timer 50 below the switching level of the comparison circuit depend on whether the control system is supplying a brake air signal. If the control system is in the state of applied i brakes, the fault current ends and the
subsequent reduction in the output of the timer 50 below
the switching level of the comparison circuit 54 that this the
The switch-off signal is cleared by turning its outlet back on
positive voltage level is switched because of the current
to the positive inlet of operational amplifier 312 from
Shutdown circuit 42 is fed via conductor 324. Ends
however, the fault current during Uiftens the brakes, see above
become the positive inlet of the function booster 312
no currents fed and the bias current through the
Resistor 316 stops the output of the operational amplifier

-65-809813 / 0991

Ground potential. The comparison circle is therefore kept locked and continues its switch-off signal. This means that the shutdown circuit 42 cannot release the brake when a brake release signal is present cause. When the brake release signal from the control system ends, the switch-off signal is deleted by the the conductor 324 to the function amplifier 312 current flowing. In this way, the comparison circuit 54 causes an unlocked condition Switching off the control system during the duration of a fault if this occurs with the brakes applied and on Locked downshift, provided that a brake release signal is present at least temporarily when the error signal is present. The dynamic test circuit 58 contains two PNP transistors 330 and 332. The speed signal from tachometer generator 22 is to the base electrode of transistor 330 and the emitter electrode of transistors 330 and 332 through a diode 334 and a resistor 336 are connected. The speed signal from the tachometer generator 24 is connected to the base electrode of transistor 332 and to the emitter electrodes of transistors 330 and 332 via a Diode 338 and resistor 340 connected.

The emitter electrodes 22fcxn £ x? 28 are all connected to ground via a resistor 340.

-66-

80981 3/0991

The diodes 334 and 338 carry the maximum wheel speed signal through a voltage divider from the resistors 336 and 340 too. If the higher wheel speed exceeds the lower wheel speed by a predetermined amount, for example corresponding to 27.4 km / h, the transistor 330 or 332 is fed to the base electrode of the lower speed signal is 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. After the predetermined time of the timer 50, the comparison circuit 54 delivers the switch-off signal to the control system to render ineffective. 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 becomes the base electrode of an NPN transistor 344 in the warning lamp circuit 56 via a resistor 346. The collector electrode of the The transistor is connected to the base electrode of a Darlington transistor 348, the emitter electrode of which is connected to ground

-67-809813 / 0991

lieso The collector electrode of transistors 344 and are connected to a lamp 350 via associated resistors 352 and 354 while the other side of the lamp is on the battery voltage is B +. If there is a switch-off signal, the normally conductive transistor 344 is blocked, to switch the transistor 348 conductive, whereupon the lamp 350 is energized and the present fault is visible indicates.

809813/0991

Claims (7)

Patent attorney Dipl.-Ir.g. K. Walther Bolivarsl ee 9 10C0 BERUH 19th W / Vh-3222 9/22/77 General Motors Corporation, Detroit, Mich., V.St.A ₀ Anti-lock control system for wheeled vehicles Patent claims: ί \, J Anti-lock control system for wheeled vehicles with devices (14 - 26) for generating a wheel speed signal to which a delay switch (30) responds and generates a control signal when the speed of the change in wheel speed exceeds a predetermined threshold value indicating the risk of locking, characterized in that a braking cycle depth integrator (32) forms a braking cycle depth signal and a control device (40) responds to the control signal and the braking H 0 9 B! 3 / U 9 9 1 ORIGINAL INSPECTED cycle depth signal responds and a BremslUftsignal during the time of the control signal, in which the Bremszyklustief ensignal exceeds a predetermined value that the braking cycle depth integrator to the wheel speed signal responsive devices (178 _and 180) that form a wheel acceleration signal and devices (184,186,188), which when applying the brake form a deceleration reference signal which represents a maximum vehicle deceleration, which disappears during the release of the brake, that integrators (192,198) integrate the sum of the acceleration signal and the deceleration reference signal to the braking cycle depth signal, which is a composite signal from a first part, the the amount by which the time integral of the deceleration reference signal liberates the wheel speed while the brake is being applied! increases, and a second part, which represents the integral j of the wheel acceleration during the release of the brake, and that on the reapplication of the brake-responsive devices (184-190) set the braking cycle depth signal output of the integrating devices to a value corresponding to its value, the with continuous summation of the deceleration reference signal and the acceleration signal would result, the braking cycle depth signal after repeated Release and re-apply the brake to a reference value, 809813/0 9 91 Exceeding size increases when the mean value of the wheel deceleration exceeds the maximum possible vehicle deceleration in order to keep the brake released so that the wheel speed increases can accelerate to the driving speed. 2. Brake anti-lock control system according to claim 1, characterized in that the acceleration signal and the deceleration reference signal are combined in a summing point (182) in which their algebraic sum is formed, from which the integrators (192, 198) the braking cycle depth signal form that the devices (184,186,188) for forming the delay reference signal from a voltage source (Z +), a a series-connected resistor (186,188) and a switch (18A) exist between the voltage source and the summing point, wherein a capacitor (190) is connected in parallel to the resistor and the switch is connected to the control device while the brake is being released, it is non-conductive and when the brake is applied, and the capacitor is switched on when the brake is applied, the brake is charged and the brake is released the resistor is discharged at a rate matched to the delay reference signal, so that the summing point receives a charge pulse when the switch becomes conductive, and the braking cycle depth signal at the outlet of the integrating -H- B 0 9 H 1 3/0 9 9 1 sets facilities to a value equal to its value that it would assume if the switch for supplying the delay reference signal was permanently switched on. 3. Brake anti-lock control system according to claim 1, characterized in that the brake cycle depth signal acting together with the control signal on the control device (40) is assigned a first high threshold value, which is greater than all braking cycle depth signals while the brake is being applied, and a second, lower threshold value while releasing the brake, so that the deceleration switch itself controls the release of the brake, and that the devices (178, 160) responsive to the wheel speed signal in the Brees cycle depth integrator (32) an acceleration or Form delay signal, and the brake cycle depth signal when a control signal supplied by the delay switch (30) disappears below the second threshold value into a first The range of friction coefficients of the roadway and the wheel load is so that the deceleration switch only controls the braking cycle controls, has a value lying above the second threshold value in a second range of the coefficient of friction of the roadway and the wheel load, so that the braking cycle depth integrator the; The duration of the brake release increased, with the -5- 809813/0991 Re-application of the brake-responding devices (104-190) adjust the integrating devices (192, 198) so that the generated braking cycle depth signal receives a value that is equal to its value, which it with continuous Summing the deceleration reference signal and the acceleration signal would achieve, and that over a number of Braking cycles is greater than the second threshold value when the mean value of the wheel deceleration is the maximum vehicle deceleration to increase the brake release time. 4. Anti-lock control system according to Claim 1, characterized in that the delay switch (30) responds to the wheel speed signal and a Control signal forms when the speed of the speed change is a predetermined, indicating the risk of locking Threshold exceeds, and this clears when the wheel speed is equal to a first reference speed, which is with the speed of the predetermined threshold value of the delay that a delay amplifier (34) is delayed provides a first reference signal when the wheel deceleration exceeds a deceleration reference level which is lower than that is the specified deceleration threshold value and this is deleted when the wheel speed becomes equal to a second reference speed, -6- 809 8 13/0991 which has a delay equal to the delay of the delay reference signal that one more responsive to the wheel speed Acceleration switch (36) provides a second reference signal in the time in which the speed of the speed change a predetermined acceleration level exceeds that of the wheel speed responsive devices (14-28, 246) deliver a third reference signal, the size of which is matched to the wheel speed, that a device (46) the larger the first or second reference signal is summed with the third reference signal to form the brake cycle depth reference signal, that a brake air lock switch (38) a brake air lock signal delivers, 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 a comparator (40) delivers a BremsIUftsignal ^ i if the sum of the braking cycle depth signal and the control] signal large than the sum of the braking cycle low reference signal and the brake air lock signal, wherein the brake air blocking signal the maximum value of the braking cycle low signal and the control signal are larger than larger than the maximum value of the braking cycle depth reference signal so that the delay switch itself causes the brake release signal, wherein the brake cycle depth signal a, the wheel speed change during -7- 09813/0991 of the brake air signal, and that a Control device (42,4A) responds to the brake release signal 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 Breas ventilation lock switch in a third mode of operation controls. 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 wheel speed signal and deliver a brake air signal when the wheel speed signal indicates a risk of locking, and a control device (44) responds to the brake air signal and the brake during the duration of the BremslUftsitnals, and that the control system contains a fault-detecting circuit (48,50,52), the depending on a sensed error, supplies an error signal to which a more responsive to the brake release signal logic circuit (54) responds and provides a switch-off signal for the control system solely through the error signal that is only deleted if the error signal and the brake release signal end, a device (268) responding to the switch-off signal and the response of the control device for the brake on the brake release signal prevented. -8-809813 / 0991 6. Anti-lock control system according to Claim 5, characterized in that the logical circle
means (316) for forming a reference signal and
a comparator (312) contains the switch-off signal
form that the comparator receives a feedback signal in the absence of the switch-off signal, the magnitude of which is smaller than the sum of the error signal and the reference signal, but larger than the reference signal, that devices (280, 44, 293) acting on the control device in the absence of a brake release signal deliver a brake application signal, the size of which is smaller than the sum of the error signal and the reference signal, but larger than the reference signal, that the comparator on the error signal, the reference signal, the feedback signal and
the brake application signal responds and delivers the switch-off signal at the time in which the sum of the magnitude of the error signal and the reference signal exceeds the magnitude 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 claims 1 to 3, characterized in that
Control circuits (30,32,38,40,42) respond to the wheel speed signal and deliver a brake air signal when the wheel speed -9-80981 3/0991 27A2991 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 air signal reveals that the control system contains an error-detecting circuit, which consists of a timer circuit (50) and several devices (48,50,52) for forming error signals, which are fed to the timer which also includes a signal indicating the brake release duration, the timer being a main error signal of a predetermined Large forms when one of the error signals or the signal indicating the brake release time is for a given Time exist, wherein means (316) for forming a reference signal and a comparator supply a switch-off signal and in the absence of the switch-off signal, the comparator receives a feedback signal whose magnitude is smaller than that Sum of the magnitude of the main error signal and the reference signal, but greater than the reference signal, is that on the Control circuits responding facilities (200,44,2 ^ 3) in the absence of a brake air signal deliver a brake application signal, whose Large is smaller than the sum of the magnitudes of the main error signal and the reference signal, but larger than the reference signal, that the comparator responds to the main error signal, the reference signal, the feedback signal and the brake application signal, and then supplies a switch-off signal when the sum of the large -10. 809813/0991 of the reference signal and the main error signal is the size of the Exceeds the feedback signal or the brake application signal, so that the switch-off signal is solely due to the main fault signal is effected, but its deletion requires the end of the main error signal and the brake release signal, and that on the switch-off signal responds to a device (268) and the response of the control device for the brake to the Brake release signal prevented. -11- 809813/0991