DE2335666A1 - MOTOR VEHICLE BRAKING SYSTEM - Google Patents

Description

COHAUSZ & FLORACK

"'" A DÜSSELDORF SCHUMANNSTR. 97

PATENT LAWYERS: Dipl.-lng. W. COHAUSZ Dipl.-Ing. W. FLORACK Dipl.-Ing. R. KNAUF · Dr.-Ing., Dipl.-Wirtsch.-Ing. A. GERBER

The Lucas Electrical Company Limited

Well "treet

GB Birmingham 11th July 1973

Motor vehicle brake systems

The invention relates to a motor vehicle brake system with wheel skid protection .

A system according to the invention is characterized by a sensor device for the delivery of a signal as a Wi eel would result in the rotation delay a vehicle wheel and a brake controller responsive to the signal to release the brakes from the wheel when the magnitude of the signal exceeds a setpoint value, the brake control device has a hydraulically driven actuator, which releases the brakes when switched on, the system further comprising a test circuit which can be actuated for a certain period of time when the brakes are not applied to the wheel is such that the operation of the actuator is checked and the system is normal Braking is returned when the actuator is not working properly.

Preferably the. Test circuit during the specified time The function is always set when the ignition switch of the vehicle is closed.

The sensor device preferably consists of a wheel sensor for Generation of a signal that depends on the speed of the wheel, and a differentiation circuit to which the signal is applied and which has an output signal representing the rotational delay of the wheel generated, the output signal from the differentiation circuit is fed to an amplifier which, when the size of the signal

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never exceeds the setpoint, a solenoid to switch on of the actuator, the actuator being used in the switched-on state to actuate a switching device which has a P 'input supplies to the test circuit, which then de-energizes the Hubmairneten ensures such that the actuator is in its rest position returns, whereby a return of the actuator to its rest position is detected by the test circuit, but a no-i-actuation of the actuator or its failure to return to its rest position is determined by the test circuit, which is then sent to the a function of the wheel skid protection circuit for a specific period of time; prevents the braking system from returning to normal braking.

^{In many arrangements, the differentiation hold-} up is used when it is first connected to an energy source to supply a signal which sets the actuator in puncture, such that the test circuit only detects the function of the actuator and then causes the actuator to return to its rest position; If necessary, however, the test circuit can have means for actuating the actuator independently of the switching of the reduction circuit in its puncture state.

The test circuit preferably also monitors proper functioning the differentiation circuit and switches the wheel skid protection circuit at the end of the certain period of time if the actuator or the differentiating circuit does not during the test period works flawlessly.

The test circuit is preferably also used for testing several hydraulic ones powered actuators used in the combustion system.

The test circuit preferably has a switching device which is biased into a conductive state and prevents operation of the wheel skid protection circuit in the conductive state, wherein the switching device by means of a first inhibitor circuit

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over a certain period of time and by a second inhibitor circuit is kept switched off after the certain period of time, the second inhibitor circuit is only set in function when the exams are satisfactory.

In some arrangements' the solenoid can only be excited when the brakes are applied, and in this case the test circuit includes means which are operable for the specified time and enable the lifting magnet to be excited in such a way that the actuator is or can be set into operation.

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The invention is explained in more detail below using an exemplary embodiment with reference to the drawings. In the drawings are:

Pig. 1 is a block diagram of the braking system in which the hydraulic and electrical arrangements are shown,

Fig. 2 is a circuit diagram showing the power supply arrangements; 3 is a block diagram of the wheel skid protection system,

Fig. 4 is a circuit diagram showing the frequency / voltage converter with that is being worked in the system,

Fig. 5 is a circuit diagram showing a differentiating circuit and a Shows amplifiers used in the system,

Fig. 6 is a sound diagram showing an inhibitor circuit with which the system is being worked on,

7 is a circuit diagram showing the safety circuit with which the system is being worked on,

Fig. 8 is a circuit diagram showing the detection circuit for a failure of the basic speed sensor;

Fig. 9 is a circuit diagram showing the rear wheel lock detection circuit shows,

Fig. 10 is a circuit diagram showing the test circuit with which in the System is being worked

11 is a circuit diagram of a monitoring unit with which in the system is being worked on.

According to Fig. 1, four wheels of a vehicle are shown schematically. The front wheels are marked with 21 and 22, the rear wheels with 23 and 24 designated. The brakes assigned to each wheel are identified by the reference number of the wheel to which the letter a is appended, and In addition, a sensor for generating a signal is assigned to the wheel, and with a frequency that is proportional to the speed of his wheel. The sensors are marked with the reference number of the wheel, to which the letter b is attached.

When the brake pedal 25 of the motor vehicle is depressed,

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Brake fluid is supplied to the brakes on the front wheels 21, 22 through actuators 26 and 27, respectively, and brake fluid is made fed through an actuator 28 to both rear brakes. If the wheel anti-skid system is not working, they play Actuators 26, 27 and 28 have no role in the function of the circuit, and it can be assumed that the brake fluid flows directly to the brakes concerned.

The wheel skid protection system has a brake fluid reservoir 29 on, the brake fluid to a feed line 31 over an electric pump J2, a check valve 33, and a Pressure switch 34 supplies. The pressure switch 34 controls a relay 35 'which in turn controls the function of the pump 32, so that a substantially constant pressure in the supply line 31 is maintained will. The line 31 supplies the inlet of three control valves 36, 37, 38, which the actuators 26, 27 and 28, respectively assigned. The valves 36, 37 and 38 have been assigned each lifting magnet 39 »41» 42, which is controlled by an electronic Control device 43 is controlled which receives inputs from sensors 21b, 22b, 23b and 24b.

If the wheel anti-skid system is not working, will the brakes are applied in the usual way as mentioned. However, under certain conditions (which will have to be described), one of the lifting magnets is excited. For example, if it is assumed that the front wheel 21 is about to close spin or slip, the electronic control device 43 feeds a signal in the lifting magnet 39 to the lifting magnet 39 to energize and the valve 36 to operate. The valve 36 serves in the actuated state to control the actuator 26 in such a way that brake fluid is kept away from the brakes 21a and at the same time a chamber within the actuator 26, through which the brake fluid is supplied to the brakes 21a, in volume so that the brakes from the wheel 21 are released. The brakes can be released from the other front wheel 22 in a similar manner

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but in the case of the rear wheels the arrangement shown solves the brakes of both rear wheels 23 and 24 when one or the other of the rear wheels is about to slip or to hurl.

Fig. 2 branches off the power supply arrangements for the overall system. The vehicle battery 51 is with its negative pole with a Power line A connected, which is connected to ground. The positive pole of the battery 51 is connected to the ignition switch 52 of the vehicle connected to one end of a relay winding 53 to which a diode D1 is connected in parallel. The other end of the winding 53 is with the line A connected via a safety circuit 54 which is connected in parallel to the battery 51 via the switch 52 and inputs from a number of points in the system, which will be described. If there are no defects in the system are, the safety circuit 54 forms a path to the power line A for the winding 53 »so that the winding 53 is energized, provided that that the ignition switch 5 ^ 2 is closed. The winding When excited, 53 closes a normally open contact 53a, which connects the positive pole of the battery to a power line B. There is another positive energy line C, which has the same voltage as the line B, but with it is connected via a fuse 50, and the line C is further connected to the emission electrode of a p-n-p transistor T1, its collector with another positive energy line D is connected, in which regulation to a voltage of 10 volts takes place in one embodiment in a 12-volt system.

Lines D and A are in series through two resistors R1, R2 connected to each other, also by a capacitor C1. The connection between the resistors R1, R2 is to the control electrode of an n-p-n transistor T2 via a Zener diode Z1 and a Capacitor connected in parallel, the control electrode of transistor T2 being further connected to line A via a resistor R3 is connected. The emission electrode of the transistor

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T2 is connected to line A and its collector is connected to line D and also to the control electrode via a resistor R4 an n-p ~ n transistor TJ connected. The transistor TJ is with its control electrode with the line A via a Capacitor CJ is connected, and its collector is through a resistor RS connected to the control electrode of the transistor T1 and to the line A via a resistor R6. The emission electrode of transistor T5 is connected to line A.

The transistor TJ provides control electrode current for the transistor T1, and thus it controls the conduction of transistor T1. That Conducting transistor T3 is controlled by transistor T2, and when the voltage on line D goes over 10 YoIt, higher control electrode current flows in transistor T2 to decrease control electrode current from transistor TJ, so that less Control electrode current flows to transistor T1 and the voltage on line D drops. When the voltage on line D is below 10 volts drops, the resulting lower \ grounding increases Control electrode current of transistor T2, the control electrode current to transistor T3, and thus the conductivity of the transistor increases T1.

Fig. 2 also shows the vehicle brake switch 55 t this is connected to the battery in series with the headlights 56 of the vehicle in parallel. The lights 56 are connected in parallel. The connection between the switch 55 and the lights 56 is via a diode D2 and a resistor R7 in series with the control electrode of an npn transistor T4, whose emission electrode is connected to line A and whose collector is connected to line B via a relay winding., to which a diode DJ is connected in parallel. The winding 57 is used in the excited state to close a normally open contact 57a, which is connected between the inertial line B and a further positive energy line E. The line E is only energized when the transistor T4 conducts. The transistor T4 not only conducts when the switch 55 closes,

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but also for a short period of time when a timer circuit 58 in is turned on in a manner to be described. All positive energy lines B, C, D and E are under the control of the Relay 53.

The emission electrode of transistor T1 is connected to line A via a Zener diode Z2 connected.

A description of the block diagram shown in FIG. 3 now follows of the system. The wheel sensor 21b, which is assigned to the wheel 21, has a toothed element which is driven by the wheel 21 and generating pulses in a take-up winding at a frequency that is proportional to the speed of rotation of the wheel. These impulses will be a frequency / voltage converter 61 which produces an output in the form of a voltage derived from the speed of the wheel depends. This output is fed to a differentiation circuit 62, the output of which is fed through an inhibitor circuit to an amplifier 64 which supplies energy to the lifting device 39. The converter 61, the differentiation circuit 62 and the inhibitor circuit 63 are supplied with power from the lines D, A, but part of the amplifier 64 and the solenoid 39 are supplied by the Lines E, A supplied with power. When the brakes of the system are applied, the solenoid 39 is energized to apply the brakes 21a from the wheel 21 when the input to the amplifier 64 indicates that the speed delay of the wheel 21 is such that a slip of the wheel is imminent.

The components assigned to the other wheels are the same, and they are denoted by the same reference numerals to which the letters a, b and c are appended. It is understood, however, that the Amplifiers 64b, 64c both supply the lifting magnet 42 with current, which releases the brakes of both rear wheels when it is energized is.

The safety circuit 54 is also shown in FIG. 3, and they

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- can have eight different inputs. One input is from a defective sensor circuit 65 »the inputs from the output terminals the transducer 61, 61a, 61b and 61c receives. Another input to the safety circuit 54 comes from a rear wheel lock detector circuit 66, which also receives inputs from the converters. A third input comes from a gate circuit 67, the Detects mass defects on the solenoids 39, 41, 42, and of

A switching device 68 which monitors the function of the pump 32 and generates an output when the pump 32 is defective. Each of the actuators 26, 27 and 28 operates a switch when turned on and a switching device 69, which is controlled by the switches, provides a further input to the safety circuit 54 · A satisfactory operation of the components 33 »34 and 35 is determined by a switching device 7I, the one provides a seventh input to safety circuit 54 and the final input comes from a test circuit 72. Any of these inputs can operate the safety circuit 54 to switch the relay 53 to de-energize and thus to interrupt the energy supply. However, as will be explained, some of the circuits work with delay, and some only when the brakes are not on.

The various parts of the block diagram are described in turn below.

Frequency / voltage converter

As shown in Fig. 4 4 ^s "fc, the transducer has two npn-Transistören T5 and T6, whose control electrodes are respectively connected via Widersiände H8. And H9 connected to the ends of the winding of the sensor 21b. The control electrodes of the transistors T5 and T6 'also connected to line A via diodes D8 and D9, respectively, and their emission electrodes are also connected to line A. The collectors of transistors T5 and T6 are connected via resistors H10 and RI3, to line C and via diodes D4 and D5, respectively connected to the line D. Further connections from the control electrodes of the

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Transistors T5 and T ^ to line D are via resistors R11 and R12 manufactured.

The collector of the transistor T ^ is connected to line D via a capacitor Go, a resistor R15 and a diode Ώ7 in series, and correspondingly the collector of the Trensistn ^ n T6 is connected to the line D via a capacitor 05, a resistor R1 / ^r and a diode Db connected in series. The connection between the resistor R15 and the diode D7 is connected to the plmispionselektror'p of a pnp transistor T8, and <*? .. <* connection between the resistor R1 / i and the diode D6 is with the emission electrode a pnp transistor T7 connected. The transistors T7> T8 have their control electrodes connected to the line D and their collectors are connected to the line A via a storage capacitor 07. The transducer generates 07 ^p ine voltage which is proportional to the speed of the wheel 21 on the capacitor. As the wheel turns, the voltage at the top of the winding becomes alternately positive and negative with respect to the voltage at the bottom of the winding. When the voltage at the top of the winding is positive, transistor Τβ is off, but transistor T5 is on, due to the current flowing through resistor R8. Current flows through the diode D7, the resistor R15> the capacitor C6 and the transistor T5> so that the capacitor 06 is landed in such a way that its upper plate becomes positive and its lower plate negative.

If the winding above is negative with respect to the winding below, turns off the transistor T5, and the lower plate of the capacitor C6 is connected to the Snergieleline C, so that the The upper plate of the capacitor C6 goes strongly positive and turns on the transistor T8, whereupon the capacitor C6 turns into the Storage capacitor 07 is discharging. The transistor T6 now conducts, and the capacitor 05 is now charged via the diode D6, the resistor R14 and the transistor T6. When the transistor T5 turns on again, the capacitor 05 becomes through the resistor R13 is connected to the line C, and it s switches the transistor T7

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a, so that the capacitor C5 is also s in the storage capacitor C7 discharges.

Two outputs are taken from the circuit. The first of these Output is that of the collectors of transistors T7 i ^ nd T8, and it goes directly to the differentiation circuit 62 as shown is. In addition, the collectors of transistors T7 and T8 are with connected to the control electrode of an n-p-n transistor T9, and the The control electrode is further connected to the connection via a resistor R17 connected between two resistors R16 and R18 which are between the lines D, A are connected. The collector of the transistor T9 is connected to the line D and to its emission electrode it is connected to line A via parallel paths, one of which is a resistor R19 and the other a resistor R20 and a capacitor G8 in series. The capacitor 08 is connected in parallel to a resistor R21, and the connection between the resistor R20 and the capacitor C8 is connected to the defective sensor circuit 65 connected. The inputs to the other circuits 62 and 65 are represented by terminals 75 »76 for identification in the drawings below.

Differentiation circuit and amplifier

In Pig. 5 shows the differentiation circuit with the amplifier, but the circuit 63 is disregarded, its task yet to be described.

Referring to Fig. 5, terminal 75 provides an input to the control electrode of an n-p-n transistor TI9 »whose collector connects to line D and the emission electrode of which is connected to the line A through a resistor R22. The emission electrode of transistor T19 is continue with line A through a resistor R2J and a capacitor C9 connected in series, and the connection between resistor R23 and capacitor C9 * is to the gate of a Pelde-effect transistor 81 through a resistor R24 and a capacitor C10

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connected in series. The source of transistor 581 is with the Connection between two resistors R29, R31 connected between a line 82 and the line A are connected. The line 82 is connected to the connection between a resistor R25 and a capacitor C13 connected in series between the lines D, A are connected. The drain and the gate of the transistor 81 are connected to one another via a capacitor C11, and the Drain is also to the collector of a p-n-p transistor T10 connected, its emission electrode via a resistor R2? 6 with the line 82 is connected. Lines 82, 2 are connected by a series circuit including diodes D11, D10 and R28, and the connection between diode D10 and resistor R28 is connected to the control electrode of transistor 5P10. The collector of the Transistor T10 is in series with the line through resistors R27, R43 82 connected, and the connection between the resistors R27, R43 is connected to the control electrode of a p-n-p transistor T11, its emission electrode connected in series to line 82 and its collector to line A through resistors R32, R33 is. The connection between the resistors R32, R33 is with the Control electrode of an n-p-n transistor T12 connected, the emission electrode are connected to the line A and whose collector is connected to the line 82 via a resistor R34. The collector and the emission electrode of the transistor T12 are through a capacitor 012 connected, the Kdlektor of the transistor T12 with the Gate of transistor 81 through a resistor R44 and the collector of transistor T12 with the control electrode of an n-p-n transistor T13 is connected through a resistor R35. The emission electrode voltage of transistor T13 is made up of three resistors R40, R41 and R47 specified, which are connected in series between the lines D, A, the connection between the resistors R40, R41 with the emission electrode d5s transistor T13 is connected. The collector of the transistor TI3 is via two resistors R37, R36 with the Line D connected, with a capacitor C3I connected to the resistors R36, R37 are connected in parallel. The connection between the resistors R36, R37 is connected to the control electrode of a p-n-p transistor TI4 connected, whose emission electrode is connected to the line D and des-

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sen collector through a resistor R38 and a diode D12 in series are connected to the control electrode of an n-p-n transistor T1 5. Its collector is connected to the line E via a resistor RI4I connected, and its emission electrode through a resistor R42 are connected to line A and also to the control electrode of an n-p-n transistor TI7. The emission electrode of this transistor is connected to the line A, and the collector of the same is connected to the line E via the solenoid 39, to the one Diode DI3 is connected in series with a resistor R39 in parallel.

As will be remembered, the signal on terminal 75 is a voltage which represents the speed of the wheel. This voltage switches the transistor TI9, which provides an input to the amplifier, which is formed by the transistors 81, T10, T11 and T12. The amplifier has a feedback path between the collector of the transistor T12 and the gate of the transistor 81 via a resistor R44 » and it is used to differentiate the input and to supply a signal at the collector of transistor T12 that the rate of change represents the speed of the wheel. During operation, the transistor T10 is conducted through the diodes D11, D10 and the resistor R28 determined, and the transistor T10 is used in conjunction with the transistor 81 to determine the conduction of the transistor T11, which in turn the conduction of the transistor T12 is determined. The tension on The collector of transistor T12 is normally between the voltages of lines D, A, and when the wheel decelerates, the voltage reaches the voltage of line D, when accelerating but it approaches the voltage of the line AB.

The emission electrode voltage of the transistor TI3 is determined by the resistors R40, R4I are set to R47, trnd is usually that Transistor TI3 not conducting. The falls during acceleration Voltage at the collector of transistor T12, and thus conducts Transistor TI3 still not. However, during a delay the voltage at the collector of transistor T12 increases until one certain rotational delay of the wheel, the transistor TI3 switched on

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will. The particular rotation delay is chosen so that the wheel is just about to slip. When the transistor T1 3 conducts, it supplies control electrode current for transistor T14 » which conducts to turn on transistors T145 and T17 so the solenoid 39 is energized. When the wheel accelerates again, the transistor T13 is switched off, and the cube magnet is de-excited.

In the case of the rear wheels, the collectors of the transistors are T17 connected with each other. When one or the other of the rear wheels is about to slip, the associated transistor conducts T1J, so that the associated transistors T14> T15 and T16 conduct and provide an input to the common rear wheel lift magnet 42.

Inhibitor circuit

The job of the inhibitor circuit is to stop unnecessary to prevent the brakes released when the vehicle is driving over a poor surface. For example, if a vehicle drives over cobblestones, one wheel is delayed with his Go up the cobblestone, and it accelerates when it goes down the cobblestone. If the vehicle is braked, the mean speed of the wheel decreases and therefore a deceleration signal occurs on. Superimpose acceleration and deceleration signals , however, this signal with a much greater frequency than one Result of the acceleration and deceleration caused by the cobblestones. These signals are not just very high Frequency, but they are also of considerable magnitude, determined to be sufficient to excite the lifting magnet 39 in FIG. So if one imagines a situation where the mean delay is such that the sad is unlikely to slip is, so that the solenoid 39 should not be excited, the solenoid 39 is still energized and de-energized, and very quickly as a result of the high-frequency signals that result from riding the bike over the cobblestones. Because also the brakes on one It turns out that the vehicle wheel takes longer to put on than to loosen

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found that a situation is quickly reached in which the brakes im. "Ultimately, are kept constantly released, so that the braking force get lost.

The inhibitor circuit shown in Fig. 6 is designed to overcome this difficulty. As can be seen from Fig. 6, the circuit is connected to the collector of the transistor T12, and it acts on the control electrode of the transistor T15 ^ in the amplifier. D "> ο inhibitor circuit has an npn transistor T22, whose emission electrode with line A, its collector with line I) via a resistor R49 and its control electrode via a resistor R48 with the collector of transistor T12k via a resistor Ή.Α6 line A and via two diodes D16, D17 in series with line A. The collector of transistor T22 is connected via a capacitor CI4 to the connection between diodes D16 and DI7, and via a resistor R51 to the control electrode of an npn -Transistor T24. The emission electrode of the transistor T24 is connected to the line A. The collector of the transistor T24 is connected to the control electrode of the transistor T15 via the diode D12.

As you can remember, the collector voltage of the transistor T12 is present normally between the voltages on lines D and A, but increases during deceleration and decreases during acceleration. Normally transistor T22 conducts, and thus there is no control electrode current for the transistor T24 present, and the capacitor CI4 discharges.

When the wheel decelerates, the voltage on the collector increases of the transistor T12, but the transistor T22 remains switched on. If the specific delay is exceeded and the brakes are released, the transistor T24 can clear the Do not disable the amplifier. When the wheel starts to accelerate again, the collector voltage of the transistor drops T12, and transistor T22 turns off. When the trans-

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istor T22 switches off, the capacitor CI4 charges through the resistor E49 iind the diode DI7 on, and if the capacitor CI4 has charged, transistor T2 / J turns on.

Of course, when the wheel is accelerated, there will be Applying the brakes again, but when the wheel is decelerated, the voltage at the collector of transistor T12 increases again, namely to such a value that without the capacitor CI4 the transistor T22 would be turned on. At this stage, however, the transistor T22 is turned off for a certain time by discharging the capacitor CI4 held off, and during that particular period of time current flowing through the resistors R49 and R51 keeps the transistor T24 switched on, thereby rendering the transistor T15 inoperative to put. At the end of the certain period of time, the transistor switches T22 on again while transistor T24 turns off. So if the certain delay during the certain period of time is exceeded, the brakes are not released. Because the frequency with which the brakes are released when the vehicle is on cobblestones is much higher than the frequency at which the brakes would be released during normal braking if the wheel is likely to slip, the specific period of time can easily be chosen so that when the wheel is is on a good surface and is about to slide until the time at which the specified deceleration occurs the second time has been exceeded, the capacitor CI4 has discharged so that transistor T24 turns off and the brakes can be released again. ON cobblestones, however an attempt to release the brakes is made before unloading of the capacitor CI4 »and in these circumstances the required Prevention caused by conducting the transistor T24.

Safety circuit

Fig. 7 shows the safety circuit together with parts from Fig. 2. There are also the various inputs to the safety circuit

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54, which in Pig. 3 and are designated 65 to 72, also identified in Fig. 7, although Fig. 3 is purely a hematic Illustration is what will become apparent from the following description and some of the circuits 65 to 72 are in Effect simply connections or switches.

Referring to FIG. 7, the lower end of the HeIaiswicklung 53 to the collector of an npn ^r J? Ransistors T25 is connected to the emission electrode is connected to the A line. The terminal M is connected to a monitoring unit (which will be described in connection with FIG. 11), which leaves a control lamp lit, a timer when the heating coil 53 is not energized. The [transistor T25 has its control electrode connected to the emission electrode of an npn transistor T26, the collector of which is connected to the collector of the transistor T25 and its control electrode via a resistor · R54 to the collector of an npn transistor.T27, the emission electrode of which is connected to the Line A and its collector are connected via a resistor R55 to a power line 82 which is connected to line A via a capacitor C90 and via a resistor R53 to the connection between the ignition switch 52 and the winding 53. The collector of transistor £ 27 is further connected via a diode D19 and a resistor R56 in series with the control electrode of a pnp transistor Τ2Θ, whose collector is connected to line A via parallel paths, one of which has two resistors R57 and R58 in series while the other includes a capacitor CI5. The connection between resistors R57 and R58 is connected to the control electrode of transistor T27. The control electrode of the transistor T28 is connected to the anodes of two diodes D21 and D22, the anodes being further connected in parallel to the emission electrode of the transistor T28 via a resistor r61 and a capacitor CI6. The cathodes of diodes D21 and D22 are connected to circuits 72 and 66 through resistors R59 and R60, respectively.

The control electrode of the transistor T28 is further through a diode

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D25, a resistor R67, a resistor R70 and a "diode 1) 2fi connected in series with the collector of a transistor T29, the transistor T29 with my emission electrode connected to the line A. and has its collector connected to the line 82 through a resistor R7I. The connection between the diode D2 ^ and dem4 Resistor R67 is + connected to the i-ei + nnj »82 via pa.-rp.Hele Were, which each contain a resistor R62 and a capacitor CI7, and also through a diode D24 and a resistor R63 in series with the connection between the brake light holder 55 and the Brake lights 56 connected. The connection between the resistors R67 and R70 are connected to the anodes of three diodes D25, D26 and D27, their cathodes via resistors R64, R65 and R66 iiit the Circuits 68, 67 and 65 are connected. The connection between the resistor R64 and the diode D25 are connected to the line A via a resistor R68. The connection between the resistors R67 and R70 is further through a diode D36 and a resistor R69 in series with the collector of an n-p-n transistor T3I connected, its emission electrode to the line A and its control electrode to the cathodes of three diodes DJ ?, D34 and D35 are connected. The anodes of the diodes D33 »D34 and D35 are via resistors R77> R78 and R79 each connected to line C, and die.Verbindungen are also connected to the circuit 7I.

The control electrode of the transistor T29 is connected to the line A via a resistor R72 and to the cathodes of three diodes D29, DJ51 and D32 via a resistor R73. The anodes of diodes D29, D3I and D32 are connected to line 82 through resistors RfA, R75 and R76, respectively, and they are further connected to circuit 6? tied together. Finally, the emission electrode of the transistor T28 is kept at a constant voltage due to a connection from the emission electrode to the connection between two resistors R81, R82 connected between the lines 82 and A.

The various possible defects caused by the safety circuit are now considered. Circuit 67 is

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ήτα End ^ ffek + · simply a connection to line E, as shown in Fig. * ■ i ^ t. From Fig. 5 it can be seen that the lower ends of the lifting magnets are connected to the line S, but if for any reason one of the lifting magnets is short-circuited at its lower end to the cash register, current flows from the line 82 through the capacitor C17, the Resistor R67, diode D26 and resistor R65 to ground, and with that capacitor C17 begins to charge. The transistor T28 is kept at a constant voltage with its emission electrode, and the voltage of the capacitor C17 is applied to the control electrode of the transistor T28 due to Λρ.τ diode D ?? created. After a delay, which is determined by the resistors R67, R65, the capacitor CI7 charges sufficiently to turn on the transistor T28, whereby BtfVuer el ektrorienstron is provided for the transistor T27. Conducting the transistor T27 switches off the transistors T26 and T25, so that the relay 53 is de-energized. Also, after transistor T27 and T28 are turned on once, current can flow through resistor R56 and diode DI9 to keep transistors T27, T28 turned on; so if a defect is found, the winding 55 can only be re-energized by opening the ignition switch and then closing it again.

The defect detection described above only takes place when the brakes are not applied. When the brakes are applied, the connection across resistor R63 and diode D? A prevents the capacitor from charging. This prevention applies to the defects that are fixed by all circuits 65, 67, 68, 69 and 71.

Circuit 65, to be described later, detects a failure in any of the wheel sensors and, if such failure occurs, connects to ground. Circuit 68 is just a switch operated by pump J2 and used to establish a till connection if the pump fails. The three circuits 65, 67 , 68 all work in exactly the same way, although the

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Neten delays can be different by adding appropriate values can be selected for the resistors E.64, E65 and R66.

The circuit only consists of three switches, the are operated by the three actuators ". Whenever one the actuators come into operation, the corresponding switch becomes connected to the anode of one of the diodes D29, D3I or D32 with a to connect positive energy conduction. As soon as an actuator is set to function, control electrode current flows to the transistor T29 to turn on transistor T29. The capacitor CI7 charges now through the resistor E70, the diode D28 and the transistor T29, and after a certain delay the capacitor switches CI7 the transistors T28, T27, so that the transistor T25 switches off as described above.

Circuit 7I effectively consists of three switches that operate from pressure are switched in the supply line 31. If any defect occurs, the anode becomes one of the diodes D33 »D34 or D35 with a positive power line connected, and thereby the transistor T3I is turned on. The capacitor CI7 now charges through the resistor R67 »the diode D36 and the resistor R69, and again after the certain delay, the transistors T27 and T28 turn on, while the transistor T25 turns off.

All of the above defects are only monitored when the brakes are not applied, but there are two defects that are monitored to determine whether the brakes are applied or not. These defects will controlled by circuits 66 and 72, both below yet to be described. Circuit 66 senses locking of the rear wheels, and when that happens, connects he the cathode of the diode D22 with a negative energy line, so that the transistors T28, T27 are turned on without a Delay occurs, with transistor T25 being turned off again. The test circuit 72 connects the diode D21 accordingly with a negative power line when the test circuit indicates

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that there is some error. Again, the transistors T28, T27 turned on to turn off transistor T25 and the winding 53 to de-excite.

Defective sensor circuit

According to FIG. 8, the series connection of the diode D27 and the resistor R66, which is shown in FIG. 7, completes a connection to the collector of an npn transistor T32, the collector of which is also connected to the line C via a diode D90. The emission electrode of the transistor T32 is connected to the line A, the control electrode is connected to the connection between two resistors R83, H84, which are connected in series between the collector of the pnp transistor T33 and the like. The transistor T33 has its emission electrode connected to the line D and its control electrode to the collector of an npn transistor T34, the emission electrode of which is connected to the anodes of four diodes D41 »D42, D43 * D44 and its control electrode to the cathodes of the diodes D37 »^ 38, D39 and D40 are connected via a resistor Ή. & 5 . The cathodes of the diodes D37, D38, D39 and D40 are connected to the anodes of the diodes D4I, D42, D43 and D44 via a capacitor G18, and the diodes are connected in pairs, the anode of the diode 37 and the cathode of the diode D4I with a terminal "J6 are connected. Corresponding compounds exist between the other pairs of diodes and the terminals 76a, 76b and 76c. the terminal 76 is the terminal shown in Fig. §4, and the terminals 76a, 76b and 76c are the equivalent lines in the other three frequency / voltage converters.

The arrangement is such that provided that all Sensors work perfectly, every wheel at the same speed

et

running, and the control electrode and the emission electrode of the transistor T34 are under essentially the same voltage. However, if one of the wheels is different from the other wheels Speed should run, a voltage arises between the control electrode and the emission electrode of the transistor T34, around the

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Turn on transistor T34. The transistor T34 now supplies control electrode current for the traensistor T33 »which in turn supplies control electrode current for the transistor T32 to complete a ground return path through the diode D27 and the resistor R66, so that the transistor T25 in Fig. 3 is switched off, as explained above has been. The circuit can be designed to operate at a certain difference between the speeds of any pair of wheels by appropriately choosing resistors R20 and R21 in FIG. The diode D90 switches off the transistor T25 when the fuse 50 blows!

Rear wheel lock detection

Referring to Fig. 9, the rear wheel lock detection circuit includes one n-p-n transistor T35 »its emission electrode with line A. and its control electrode via resistors R86 and R87 with the connections 83 and 8;, a are connected. The collector of the transistor T35 is connected to the line D through a resistor R88, and it is further in via a resistor E93 and a resistor S94 Row connected to line A «The connection between the resistors R93> H94 is with the control electrode of an n-p-n transistor T37, the emission electrode of which is connected to line A. Furthermore, an n-p-n transistor T36 is provided, the Emission electrode connected to line A and its control electrode connected to terminals 84 and 84a via resistors R89 and R90, respectively is, furthermore via diodes I> 96 and D97 in series with the line A. The collector of transistor T36 is connected to the connection between connected to the diodes D96 and D97 via a capacitor G20, further via a resistor R91 to the line D and via a resistor R92 with the control electrode of an n-p-n transistor T38. Of the Transistor T38 has its emission electrode connected to line A and its control electrode connected to line A via a resistor R95 connected in parallel with the collector emission electrode path of transistor T37. The collector of transistor T38 provides one Input to the safety circuit through resistor R60 and diode D22 in Figure 7, and it is also through diodes D46 and D47, respectively connect with the connections 85 and 85a.

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oar

Terminals 84 and 84a are connected to the frequency / voltage converters associated with the rear wheels. The location of port 84 is in Pig. 4 indicated, and as can be seen, does the control electrode receive? of the transistor T36 a signal directly from the corresponding capacitor C] in the rear wheel frequency / voltage converter, so that the control electrode voltage of the transistor T36 depends on the speed of the rear wheels. The connections 83 and 83a are connected to the frequency / voltage converters, which are respectively assigned to the front wheels. The position of the connection 83 is also shown in Fig. 4, and it can be seen that, due to the connection of the connection 83 with the emission electrode of the transistor T9, the voltage at the connection 8 * for a certain wheel speed is generally corresponding to the corresponding frequency voltage converter is slightly less than the voltage at terminal 84. The reason for this will still be apparent. It should also be noted that the collector of the transistor T ^ o is connected in series with the connection between the brake light switch 55 and the lights 56 via a diode D48 and a resistor HI42, and this connection is also connected to the line via a resistor RI43 A is connected.

Provided that the front wheels of the vehicle are in operation run at a speed that corresponds to a low vehicle speed of the order of 8 km / h transistor T35 is switched on, and it takes control electrode current away from transistor T37, which is thus switched off and disregarded can be left. When the vehicle brakes are not applied, diode D48 can conduct current that flows through resistor R9I, namely via the lights 56> whereby this current is not sufficient to to keep the lights 56 on, but to ensure that the transistor T38 does not conduct, so that the circuit in effect is disabled. The resistor R143 forms this current path, if the lights 56 are burned out. However, if accepted When the vehicle's brakes are applied, switch 55 is closed and diode D48 is reversely biased and does not matter in the function there? Circuit. The resistor R142 protects the diode D48 from switch-on voltage surges. A Dre-

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hung of the rear wheels generates signals at connections 84 and 84a, which serve to keep the transistor T36 switched on, and current flowing through resistor R91 thus flows through transistor S36, and transistor T38 switches off. Simultaneously the capacitor C20 is discharged. In normal operation, the transistor T38 does not turn on at all. When out for some reason, however, the system on the rear wheels does not work, if both rear wheels start to slip, the control electrode drive removed from transistor T36, and after a brief delay during which capacitor C20 charges, transistor T36 turns off, and through the resistor R91 flowing current now flows through the resistor R92 to the Turn on transistor T38. Conducting transistor T38 provides a path to ground through diode D22, and that has the effect of like above in connection with Pig. 7 explains that the transistor T25 is switched off, so that the '"' relay winding 53 is de-energized will. Conducting transistor T38 also provides a path to ground from terminals 85 and 85a associated with the amplifiers that monitor the front wheels of the vehicle. The position of the Connection is in Pig. 5, and as can be seen, shuntet one Effectively conducts the diode D46 control electrode current of the transistor TI5 in Pig. 5 to ground, so that transistor T15 does not conduct can. The equivalent transistor T15 in the amplifier, that of the other Front wheel is assigned, also ceases to conduct, so that the circuits to the front wheel lift magnets are separated.

The job of capacitor C20 is to ensure that when the rear wheels lock momentarily during braking, the transistor T36 remains switched on and the transistor T38 does not conduct. A momentary locking of the rear wheels is acceptable, however, if the rear wheels lock up as a result of a defect and the system still kicks in to put the brakes in the usual way to loosen and tighten the other wheels, it is possible that the vehicle is a strong turning force which can cause the entire vehicle to turn.

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When the vehicle comes to a normal standstill, transistor T36 turns off, although of course it is not necessary to turn on transistor T38. As you can remember, the signal at the connections 83 and 83a is somewhat smaller than the signal at the connections 84 and 84a for a certain speed of a wheel. For this reason, the transistor T35 switches off if the vehicle comes to a standstill before the transistor T36 does. When the transistor T35 turns off, the transistor T37 turns on, and therefore when the transistor T36 is turned off, the transistor T38 is not turned on because current flowing through the resistor Έ $ 2 flows through the transistor T37.

The reason the gearshift is inoperable except during braking is done, by means of the diode D48, is that a false display should be prevented when the front wheels on one Front wheel drive vehicle skid during acceleration.

The job of diodes D96 and D97 is to compensate for to create the possibility that all vehicle wheels lock in transition and then released at the same time. If this happens without the diodes D96 and D97 being provided, it is possible to that the transistor T38 receives control electrode current in the transition and turns on. In this circumstance, however, diode D97 will be forward biased while diode D96 will be reverse biased so that the collector voltage of transistor T36 will drop rapidly can, and this effectively disables the capacitor C20. As a result, the transistor T38 can in transition received no control electrode current and the problem is solved. In normal operation, diode D96 is forward biased, the diode D97, on the other hand, is reverse biased and capacitor G20 works in the manner described.

Test circuit

The test circuit, which includes a timing network, is shown in FIG. By first considering the time network, an n-p-n transistor T39 is provided, the control electrode of which is connected to the emission

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electrode of an n-p-n transistor T41 is connected, the collectors of transistors TJ9 and T4I connected to line C. are. The transistor T39 is connected with its emission electrode via a diode D5I and a resistor R97 in series with the line A, and the emission electrode is further through a diode D52 and resistor R7 in series with the control electrode of the transistor T4 connected as shown in Fig. 2 so that when transistor T39 conducts, transistor T4 is turned on, and aar by current flowing through diode D52 and resistor R7. The connection between diode D5I and resistor R97 is also connected to a power line 99, so that the line 99 is energized when the transistor T39 is switched on.

The control electrode of the transistor T41 is via resistors R98, R99 connected in series with line C, and the connection between the resistors R98 and R99 is connected to the collector of an n-p-n transistor T42, whose emission electrodes are connected to the line A and its control electrode to the collector via a resistor R102 an n-p-n transistor T43 are connected. The transistor T43 is with its emission electrode with the line A, with his Collector with the line A through a capacitor C21 and with his Collector continues through a resistor RIO3 to line C as well with its control electrode via a diode D54 with line A. and in series through a capacitor C22 and a resistor R101 connected to the collector of transistor T42. The connection between the capacitor G22 and your resistor R101 is via a Diode D53 and a resistor B100 in series with the connection between connected to resistors R98 and R99.

The rest of the test circuit has three pairs of transistors T44, T45, T46, T47, T48 and T49. The transistors T44, T46 and T48 are with their emission electrodes each with the collectors of the transistors T45> T47 and T49 connected, and the emission selectors of the Transistors T45, T47, T49 are connected to line A. The control electrodes of the transistors T45 »T47 and T49 are via resistors R 104, RI05, RIO6 connected to ports 88a, 88b, 88c,

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and the control electrodes of the transistors T44> ¹ SA ^, T48 are connected to line 99 via resistors E107, E10_8, E112. The Koi lnktoren of the transistors T44 and T4-6 are through diodes D55 'and D56 connected to terminals 85a and BR, and the collector of the transistor 748 is ^m through diodes D57 ¹¹¹¹ O- ^ 58 it the terminals 85b, 85c connected.

In addition, an n-p-n transistor T51 is provided, its emission electrode are connected to the line A and its collector via a resistor El 19 nit the line D. The control electrode of the transistor T51 is across a resistor B120 to the cathodes of five Diodes D59, D61, D62, Do? and D64 connected. The diodes D59 »D6I are with their anodes via resistors R115 and E114 with the connections 98b, 98c, while diodes D62, D63 and D64 with their anodes via resistors R115 »RII6 or EII7 with the line D are connected. The connections between the resistors EII5 ,. E116 and EII7 and their associated diodes D62, D65, D64 are respectively verburiden with the collectors of 'transistors T49> T47 and T45. The collector of the transistor T51 is further through a capacitor G28 and a resistor R126 in series with the "connection between two diodes D65, D66 connected, which are connected in series between the control electrode of an n-p-n transistor T52 and the line A. are. The transistor T52 is with its emission electrode connected to line A and to its collector via a resistor RII9 to line D. The collector is further over ■ a capacitor C2J connected to the line A, also through resistors RI09, R110 and R111 with the control electrodes of the transistors T45, T47 and T49. The control electrode of transistor T52 is connected to the collector of an n-p-n transistor via a resistor R122 T53 connected, the emission electric is connected to the line A, whose collector is connected to the line D via a resistor RI23 is connected and its control electrode via a resistor R121 is connected to the collector of transistor T52. The collector of the transistor T53 is through a resistor EI25 connected to the collector of an n-p-n transistor T54, its emission electrode to the line A and its collector via a

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Capacitor C24 with line A and also with the control electrode an n-p-n transistor T55 are connected. The transistor T55 is with its emission electrode with the line A and with its collector connected to the safety circuit in Pig. 7 is shown. The control electrode of the Transistor T54 is connected to the emission electrode via a resistor RI24 of the transistor T39 connected.

As related to Pig. Recalling 7, will be the relay winding 53 de-energized if transistor T55 conducts at any point in time. When the ignition switch is closed for the first time, the Energy lines C, D are energized, and current flowing through the resistors R99, R98 switches on the transistors T41, T39. The capacitor C21 initially keeps the transistor T42 switched off. Current also flows through resistor R101 and capacitor 022, to turn on the transistor T43, but after a certain period of time the capacitor G22 is charged, and the transistor T43 turns off. When transistor T43 turns off, control electrode current flows to transistor T42, which turns on Remove control electrode current from transistors T4I and T39, so that the transistors T4I and T39 turn off. The timer works for a certain period of time, for example one second, to supply current to line 99 and also to the transistor Keep T4 switched on. Because transistor T4 is kept on, current is not only conducted to line B, but also to line E, which supplies the amplifiers, even if the vehicle's brake pedal is not depressed at this stage.

If the timer works for one second, Current flowing through resistor R124 switches the transistor T54 a. Current flowing through resistors RI23 and R125 can now flow through the transistor T54, and thus the transistor T55 cannot be switched on during the period of one second will.

The task of the circuit is to puncture the wheel lock

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check the protection system for a period of one second and prevent the system from being operated if any one of several specific defects is detected.

During the delay time, a delay signal is to be simulated that causes the actuators to be actuated. This can be done by feeding a suitable signal into the amplifier _t concerned, but when working with the arrangement shown, when the circuit is first connected to the current source until the various components work in, each amplifier receives in effect Signal that simulates a delay beyond the nominal maximum so that each of the actuators is put into operation. It goes without saying that a function of the actuator in question is enabled by virtue of the connection through the diode D52 to the control electrode of the transistor T4 for the connections 88a, 88b and 88c, the connection 88c being connected to the actuator for the rear wheels. When the terminals 88a, 88b and 88c receive their signals, the transistors T45> T47 imci T49 are switched on, and since the line 99 is live at this moment, the transistors T44 »T46 and T48 also switch on. Conducting the transistor T44 through the diode D55 serves to apply the connection 85 to ground. The connection 85, as will be remembered, is shown in Fig. 5, and when it is connected to ground, it clamps the control electrode of the transistor T15 in the amplifier, which is assigned to one of the front wheels, so that the solenoid 39 is de-energized and the actuator in its rest position begins to return. Correspondingly, the diode D56 disconnects the amplifier that is assigned to the other front wheel, and the diodes D57 and D58, which are both switched by the transistor T48, disconnect the two amplifiers that are assigned to the rear wheels. The movement of the actuators during the delay time of one second does not significantly affect the function of the vehicle brake system.

When all transistors T44, T45, T46, T47 and T48 and T49 are conducting,

309885/1094 " ² ^ -

becomes the control electrode of the through diodes D62, D63 and D64 Transistor T5I current flowing through the transistors T45, T47 and T49 diverted, but the transsitor T5I only switches off when there is no current from diodes D59 or D6I or from a of which is received. The diodes D59 and D61 receive their inputs from the terminals S98b, 98c, and the position of the terminal 98 is shown in FIG. Terminal 98 is one of the rear wheel differentiation circuits assigned, and as can be seen, falls provided that the rear wheel differentiation circuit operates, the voltage at terminal 98b at zero during the duration of one second, and thus the signal via the diode D59 disappears · The connection 98c is of course the other Rear wheel differentiation circuit assigned, and provided that both differentiation circuits, which are assigned to the rear wheels, and all actuators work properly, switches transistor T51 turns off during the delay time.

As soon as the actuator switch is closed again, what happens if the system works fine, because the amplifier from the diodes D55> D56, D57 and D58 are prevented from working, too if the rear wheel differentiation circuits are working properly, will control electrode current to transistor T51 via the diodes D62, D63, D64 are fed back again, and the transistor T5I switches see you again. While transistor T51 is off, are the transistors T52 and T53 switched on and off. The condenser C23 prevents the transistor T53 from being conducted when the ignition switch closes. If the transistor T51 is again turns on, the bistable circuit formed by transistors T52 and T53 and their associated components switches so that the transistor T53 is switched on and the transistor T52 is switched off is. When transistor T52 turns off, flows through the current flowing through the resistor RII9 now through the resistors R109, Silo and R111 to hold transistors T45, T47 and T49 like that that the transistors T44> T46 and T48 can remain conductive until the Energiezuei * i-jleitung is removed from the line 99 and the Diodes D55, D56, D57 and D58 do the work of the amplifiers for the rest

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stop the delay time.

Liunmehr has reached a situation in which a series of operations during the delay ^ ζext have been checked, and as a result of a If the check is successful, the circuit is left in a state in which the transistor T53 is switched on. At the end of the delay time Transistors T39 and T41 turn off as above mentioned, and thus a control electrode drive is removed from transistor T? 4. Now, however, the transistor T53 conducts and takes control PI Electrode current away from transistor Tfjfj so that transistor T55 does not directs. The capacitor C24 prevents the transistor Tf35 from conducting in transition at the beginning of the test period.

If any of the tests are unsuccessful, will the required clearance is not performed, and the TmnsiBor Tfj1 does not turn off and on again. In this circumstance remains the bistable circuit in its normal state with transistor Tfj2 conducting and transistor Tfj3 off. At the end the delay time, the transistor TfJ4 turns off, and current flows through resistors R12J and R125 to turn on transistor Tf35, so that the relay winding is de-energized and the wheel anti-skid system does not work to keep the normal braking system of the vehicle working.

FIG. 10 also shows the components associated with the monitoring unit shown in FIG. 11. The line 99 is with the positive pole of the battery 51 via the cathode-anode path of a diode D96 and connected to a starter switch 200 of the vehicle. Whenever the When starter switch 200 is closed to start the vehicle, line 99 assumes a positive voltage. Furthermore is in series between the lines C, A connected a pair of resistors R142, R143, whose Connection connected to the control electrode of a p-np transistor T92 is, whose collector is connected to the line 99 and via a diode D95 whose emission electrodes are connected to the line D. The control electrode voltage of the transistor T92 is through the resistors RI42

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and BI45, and provided that the line D is under the If the voltage is correct, transistor T92 does not conduct. However, if the voltage on line D drops below a set point, for example 11 volts, transistor T92 conducts, and line 99 assumes a positive voltage. So, as can be seen, is located 10, line 99 is at a positive voltage during the delay time when an attempt is made on the motor ziu start, or when the stabilized voltage drops below 11 volts.

Monitoring unit

Vie in Pig. 11, the positive terminal of the battery 51 is shown with a Power line 100 via the ignition switch 52 of the vehicle and a Control lamp 81 connected in series. The line 100 is connected to the line A via switches 101, 102 in a parallel arrangement. The line 100 is also connected to the emission electrode of a p-n-p transistor Τ9Θ, the control electrode of which is connected to the collector of an n-p-n transistor T97 is connected, the emission electrode is connected to line A via a resistor RI56. the Control electrode of transistor T97 and the collector of the transistor T98 are connected to each other and to line 100 through a resistor R155, and the control electrode of transistor T97 is further Connected via a plug-in coupling 201 to the collector of an n-p-n transistor T96, the emission electrode of which is connected to line A. and whose control electrode is connected to the line D via a resistor RI54. The transistor T96 is also connected to its control electrode connected to the collector of an n-p-n transistor T95, its control electrode with the line A via a resistor R153 and its diode D99 is connected in parallel and its Control electrode further via resistors R152 or R.I5I with the connection M (Fig. 2) and connected to line 99 (Fig. 10).

The switches 101, 102 are each closed when the handbrake of the vehicle is attracted and when the level of the liquid drops below a full position in the brake fluid reservoir. A

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Closing one or the other of the switches 101, 102 switches the lamp 81 off. Any number of switches can of course be provided in parallel for the driver to give a hint. Other switches that can be used in certain vehicles are pad wear switches that indicate when the brake pads are worn, and a pressure differential switch, which in a system with a two-circuit hydraulic system is closed when the pressures in the two circuits differ differ.

The 7 _: ampe 81 is also switched on when the transistor pair T98, T97 is switched on. The transistor pair T97, T98 is switched on by current flowing through the resistor R155, except when this current is diverted via the unit 201 and the transistor T96. The transistor T96 is normally kept conductive by current flowing through the resistor R154, so that the transistor pair T97, T98 is switched off. However, if there is a defect in the system resulting in a voltage at terminal M, transistor T95 turns on to remove control electrode current from transistor T96 so that lamp 81 is turned on. Transistor T95 continues to turn on when a voltage is present on line $$ , and as recalled with reference to Figure 10, this occurs during the delay time when the engine is started and when the voltage on line D falls below a set point falls off. Under any of these circumstances, transistor T95 is turned on, transistor T96 is turned off, and transistor pair T97 and T98 are turned on to turn on lamp 81.

The unit 201 has a number of quick couplings that are used in the system. If any of these quick couplings is disconnected, the pair of transistors T97 and T98 are turned on by current flowing through resistor E155. The unit 201 can Connector for a real connection between the controller and the vehicle have, so that the lamp 81 is also switched on when the regulator

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removed from the vehicle.

It will be understood that a wide variety of modifications can be made in the system. In the preferred embodiment there are three actuators and four wheel sensors. It is not difficult to have four actuators in such an arrangement if that is believed to be advantageous for a particular application. Furthermore, instead of two rear wheel speed sensors, you can work with a single rear wheel sensor that acts on the drive to the rear wheels. If necessary, only two actuators can be used, one for the rear wheels and one for the front wheels, and in this case ^"11 can either sensors with two wheel or work dderehzshlsensoren four R?, Again depending on the application.

In the event of a defective sensor circuit, it is not decisive to control the outputs of the frequency voltage converters, although that is preferable that the work of the frequency-to-voltage converter is automatically checked at the same time. The sensor output -j can, however be compared in other ways, either as a direct current or an alternating current circuit.

Expectations

309885/1094

Claims (8)

1 J E vehicle braking system with wheel skid protection, marked by a sensor device for supplying a signal as a reproduction the rotational deceleration of a vehicle wheel and a brake control device responsive to the signal to release the brakes from the wheel, when the magnitude of the signal exceeds a setpoint value, the brake control device being a hydraulically driven actuator which releases the brakes in the switched-on state, the system further comprising a test circuit which determines one Can be actuated for a while when the brakes are not applied to the wheel are such that the operation of the actuator is checked and the system is returned to normal braking when the actuator not working properly. ?. System according to Claim 1, characterized in that the test circuit then always put into operation for the specified period of time when the ignition switch of the vehicle is closed. 3. System according to claim 1 or 2, characterized in that the sensor device has a wheel sensor for generating a signal which depends on the speed of the wheel, furthermore a differentiating circuit to which the signal is applied and the input / output signal as output Rotational delay of the wheel generated, the output signal from the differentiation circuit being fed to an amplifier which, when the size of the signal exceeds the setpoint value, energizes a lifting magnet sum switching on the actuator, the actuator being used in the switched-on state to actuate a switching device which an input to the test circuit supplies, which then ensures a jjäitregen of the solenoid, such that the actuator returns to its rest position, with a return of the actuator? in its rest position by the test circuit, iedooh a non-actuation of the actuator or its return to its rest position is determined by the P & rüfschalts, which then at the end of the certain period of time prevents a function of the wheel ■ Bohlpudpulpchsltung, so that the brake system to normal braking returns. 7 / a / Ti -P- 309885/1094 ORIGINAL BATHROOM 4. System according to claim 3> characterized in that the differentiation circuit ^1, is used that sets the actuator in function at their first Yerbinchmg with a iiiergi equelle cure providing a signal such that the test circuit detects only the puncture of the actuator and then a return causes the actuator in its rest position. 5. System according to Claim 3, characterized in that the test circuit has means for actuating the actuator independently of the switching of the differentiation circuit into its functional state. 6. System according to one of claims 3 to 5 »characterized in that that the test circuit · also ensures proper functioning of the differentiation circuit monitored and the wheel skid protection circuit at the end of the certain period of time, if the actuator or the Differentiation circuit does not work properly during the test period. 7. System according to one of Claims 1 to 6, characterized in that that the test circuit is also used to test a plurality of hydraulically driven actuators in the brake system. 8. System according to one of claims 1 to 7 »characterized in that that the same test circuit for testing several hydraulically driven Actuators used in the braking system. 9. System according to one of Claims 1 to 8, characterized in that that the solenoid can only be excited when the brakes are applied, and that the test circuit has means which during de ^ determined Period of time to enable the lifting magnet to be energized can be actuated in such a way that the actuator is put into operation. 309885/1094