Itt Industries, Inc.

Itt Manufacturing Enterprises, Inc.

Alfred Teves Gmbh

Itt Automotive Europe Gmbh

Hans-Wilhelm Bleckmann

Heinz Loreck

Jochen Burgdorf

Lutz Weise

Juan Belart

Dieter Kircher

Helmut Fennel

Peter Lohberg

Michael Zydek

Hans-Dieter Reinartz

Peter Volz

Helmut Steffes

Dieter Dinkel

Erhard Beck

Norbert Ocvirk

Hans Wupper

Karlheinz Haupt

Hermann Esselbruegge

Michael Zydeck

In so-called active sensors which transmit an output signal to an electronic controller, the amplitude of the output signal depending neither on the speed of the encoder nor on the distance between the sensor and the encoder, the problem is that the output signal does not permit identifying whether the air slot size set between the sensor and the encoder is chosen sufficiently small to ensure an appropriate amplitude of the input signal, generated in the sensor, even when dynamic increases in the air slot occur. If the input signal induced by the encoder in the sensor is too low, a sensor-inherent hysteresis threshold is not exceeded, and no output signal is generated. To prevent the sensor from being inadvertently operated at the limits of its maximum permissible air slot, according to the present invention, the sensor-inherent hysteresis threshold is changed over to the higher hysteresis threshold for testing purposes. If a sufficient input signal is generated even by way of this higher hysteresis, it may be supposed that the sensor is correctly mounted.

Active motion sensor having air gap checking function

In normal operation, a sensor element emits information only as to whether two or more field-sensitive components are located in peripheral zones of identical or different electromagnetic field strengths of a pulse generator. In order to permit sensor elements of this type determining immediately upon activation of a supply voltage whether an identical electromagnetic field strength on both components corresponds to a zone of low (L) or high (H) field strength, according to the present invention, the sensor element, upon activation of the supply voltage, is initially operated so that the absolute field strength is measured for a given time. If there is a difference circuit between two field-sensitive components (,), the measurement is carried out because one of the components is temporarily switched off, both components are connected in parallel, or both components are connected in series.

Motion sensor having a timer and a switch for measuring absolute field strength

Active motion sensor having post-assembly air slot signal adjustment

Redundant wheel sensor signal processing in both controller and

Anti-lock hydraulic brake system

This is a circuit configuration provided for an anti-lock-controlled brake system and serving for processing sensor signals obtained by wheel sensors (5) and for generating braking pressure control signals. This circuit configuration contains two microcontrollers (1, 2) interconnected by data exchange lines (7). The handled signals are concurrently processed by the microcontrollers independently of one another and the exchanged signals are checked for consistency. A deviation of the exchanged signals which is due to malfunctions is signalized to a safety circuit (8) which, thereupon, interrupts the power supply to the solenoid valves (Ll . . . Ln). The monitoring signal (WD1, WD2) fed to the safety circuit (8) is a predetermined alternating signal in case of consistency of the exchanged signals and in case of proper operation of the circuit configuration. The safety circuit (8) compares the alternating signal with a time standard derived from a clock generator (TG2, TG3) which is independent of the operating cycle (TG1) of the microcontrollers (1,2). A change in the alternating signal, as well as a failure in the time standard, causes a cut-off of power supply and, hence, of anti-lock control.

Circuit configuration for an anti-lock-controlled brake system

A circuit configuration for monitoring the final stages of a plurality of valves, particularly the power transistors (LT1-LT4) and their circuitry, for defects as well as for leakage currents or by-path currents comprises a comparator circuit (1), an OR-link (2) and of a further comparator element (XOR4). By way of the monitoring circuit, the actuation connections (S1-S4) of electromagnetically operable valves are connected to a sole output (A3). By applying short test pulses to the actuation inputs (E1-E4) of the final stages (LT1-LT4) and by comparing the signal variation at the output (A3) with the test pulse variation defects, leakage currents and the like are detected.

Circuit configuration for monitoring the final stages of a plurality of

In the braking system of a motor vehicle, a hydraulically or electromagnetically actuatable valve is inserted into the return line to control and monitor hydraulic brake slip control devices supplied with energy from an external source. This valve opens or closes the return passage of hydraulic fluid from pressure reducing valves of static brake circuits in dependence upon the dynamic pressure developing in the booster chamber of brake valve network or in the prechamber of the master cylinder upon application of the brake or upon start of the brake slip control. Pressure reduction in the static brake circuits for preventing a wheel lock-up will thereby be avoided, if in the event of a control action no dynamic pressure develops in the booster chamber or in the prechamber on account of a defect.

Method and apparatus for controlling and monitoring hydraulic brake slip

To control a brake slip control apparatus, the rotational behavior of the wheels or of the axles is sensed with the aid of sensors, and the sensor signals for the generation of valve control signals, by which the braking pressure at the wheels is controlled dependent upon the wheel rotational behavior, will be processed electronically. On the basis of these sensor signals, valve control signals will be produced in at least two independently acting, synchronously driven logical circuit units, which may be integrated circuit configurations or complete 'microcontrollers' or single-chip-microcomputers, and the signals' waveforms of each of the two circuit units can be compared and checked for agreement externally and internally at corresponding locations within the two circuit units. Upon the occurrence of variations in the external and/or the internal signals or in the signals' waveform, there will be caused, initiated or prepared a complete or partial disconnection of the brake slip control. A circuit configuration for implementing this method comprises a synchronizable astable multivibrator to process the sensor signals, a valve driver circuit including a level adjusting circuit as well as monitoring circuits for disconnecting the current supply for the regulator and for blocking the valve drivers in the event of interferences or variations in the signals' waveform occurring within the two circuit units. The monitoring circuits, one for each of the two circuit units, act on at least one transistor connected in series in the exciter circuit of a relay, by which the current supply is established or interrupted.

Method and circuit for the control of a brake slip control apparatus

To monitor and control hydraulic brake slip control devices supplied with energy from an external source and intended for use on motor vehicles equipped with several brake circuits, a check is kept on the fluid level in the reservoir holding the hydraulic fluid and on the pressure in the chambers supplied with the external energy. When the fluid level drops, which is detected by a reservoir level warning device, or when the pressure drops causing pressure warning switches to respond, the brake slip control will be only partially deactivated initially by halting the reduction in pressure in the static brake circuits and inhibiting the dynamic fluid flow into the static brake circuits. The dynamic brake circuit will continue to allow a controlled deceleration of the connected wheels. The partial deactivation will be initiated immediately or with a time delay or only if the error signals continue to be present beyond a predetermined period of time. Depending on the duration of the error signals or following the lapse of a predetermined period of time, the brake slip control will be deactivated fully or, if the error signals cease, the partial deactivation will be cancelled.

Method for monitoring and controlling hydraulic brake slip control

A control arrangement of a hydraulic vehicle braking system provided with antiskid control equipment includes a master cylinder device which is actuatable by a brake pedal and is provided with at least one master piston cooperating with an associated replenishment chamber. The replenishment chamber is hydraulically connected through a substantially radial bore with the secondary side of the master piston. An axially displaceable circumferentially sealed positioning piston is disposed at the secondary side of the master piston, and a piston rod of the master piston concentrically and sealingly passes through the positioning piston. The piston rod of the master piston is provided, at its free end which is closer to the brake pedal, with an enlarged circumferential projection which can be brought in engagement with an associated circumferential edge of the positioning piston upon depression of the brake pedal and after admission of the pressurized hydraulic fluid from the auxiliary energy source to the secondary side of the master piston in such a manner that the master piston is moved into a defined position during antiskid control operation. Alternatively, this engagement of the positioning piston can take place with a circumferential projection of a throttling valve which is interposed between the brake pedal and the master cylinder device.

Pressure controlling arrangement for use in a vehicle brake system

An arrangement for controlling the pressure in brake actuating cylinders incorporated in a hydraulic vehicle braking system which is supplied with auxiliary energy includes a master cylinder device having at least one master piston accommodated in a bore communicating with a replenishment chamber. A brake pedal actuated control valve device is arranged between the master cylinder device and the brake pedal and controls the supply of auxiliary energy from an auxiliary energy supply source through a hydraulic conduit to the replenishment chamber. Electromagnetically actuatable control valves are included in the braking circuit and locking of the wheels by controlling the operation of the wheel brake actuating cylinders. Furthermore, there is provided a return conduit to a hydraulic reservoir which incorporates a normally open hydraulic shutoff valve which closes when the pressure of the auxiliary energy drops below a predetermined threshold value. An electromagnetically actuatable normally closed valve is interposed in the hydraulic conduit, being opened when there is a need for antiskid control action. Another valve connects the replenishment chamber with the reservoir when the brake pedal is in its rest position, while discontinuing such communication during the antiskid control action. Thus, pressure in the replenishment chamber is relieved during normal braking operation and rises up to that of the auxiliary pressure source during antiskid control operation. All of the valves which are hydraulically actuatable in dependence on the pressure of the auxiliary energy can be structurally incorporated in a valve unit.

Arrangement for controlling the pressure in brake actuating cylinders of

A digital phase-locked loop for speed measurement, in particular for use in antiskid control systems, for the conversion of the frequency of an input pulse sequence, proportional to a speed, into a digital numerical value to be used in the digital arithmetic unit for an antiskid control system is provided wherein there is a certain numerical value which will always be the same which is allocated to any input pulse sequence and which can be applied to a first storage register and added to the contents therein. At regular intervals, determined by a clock generator, a positive digital output numerical value is generated by a detector if the content of the first storage register is above a predetermined upper limit and a negative digital output numerical value will be generated if the contents of the first storage register are below a predetermined lower limit. Furthermore, the respective digital output numerical value of the detector can be added to the content of a second storage register, observing a correct sign. The contents of the second storage register are at digital numerical value corresponding to the frequency of the input pulse sequence, with that digital numerical value always being subtracted from the content of the first storage register upon each clock pulse generated by the clock generator.

Digital phase-locked loop for speed measurement, in particular for use

This invention discloses a device for converting the rate of a pulse train which is proportional to the velocity of a vehicle wheel into a binary number for use in a digital computer for anti-skid control systems wherein the pulse train is supplied to a comparator, the output of the comparator being coupled to the input of a storage register which cumulatively adds to its contents, taking due consideration of the sign of the input. A frequency generator which is controlled by the contents of the storage register, with the comparison pulse train produced by the generator being supplied to the comparator and an adapter being added to establish a difference between the frequencies of the two pulse trains in the form of a binary number, which binary number is supplied to said register so that the content of said register represents the binary number corresponding to the frequency. The comparator and the register are both controlled by a clock pulse generator.

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Bad Nauheim, Germany

Hans-Wilhelm Bleckmann