Abstract:
A circuit for a brake system with pressure fluid distribution, anti-lock control, and traction slip control. The circuit includes circuits to monitor the brake system and to change over or disconnect the control in response to defects and/or the respective control situation or driving situation. Upon failure of any one of the sensors which sense wheel rotation behavior or one sensor per axle or in the presence of an incorrect sensor signal, the vehicle reference speed is produced on basis of the intact sensors, and an electronic brake force distribution control function is still possible, however, an anti-lock control or a traction slip control is prevented. When the defective sensor is a rear-wheel sensor, both rear wheels are controlled synchronously. Upon the occurrence of a defect or a malfunction of a hydraulic pump system or when the supply voltage drops, an electronic brake force distribution control function is possible until a defined limit value, however, an anti-lock control/traction slip control is prevented.
Abstract:
To control the braking pressure in the wheel brakes of a slip-controlled hydraulic brake system for automotive vehicles with all-wheel drive and with lockable or automatically locking differentials (2, 3), a circuit configuration is provided which influences the variation of the vehicle reference speed (v.sub.REF). This is to say, in the event of the wheel (v.sub.Rn) which is momentarily decisive for the formation of references becoming instable, the reference speed (v.sub.REF) will first be declined with a relatively flat gradient which corresponds to a vehicle deceleration at a low frictional coefficient. A decrease of the vehicle reference speed (v.sub.REF) with a very steep gradient will follow after a predetermined period of time (T.sub.1). This decrease is continued until the vehicle reference speed (v.sub.REF) reaches the decisive wheel speed again or falls thereunder. To avoid oscillations, the change-over of the reference (v.sub.REF) after the attainment of the wheel speed curves (v.sub.Rn) will not be effected until after a predetermined time of delay (T.sub.2 or T.sub.3).
Abstract:
The circuit configuration for a brake system having an anti-locking control generates pulse-type brake pressure control signals. For pressure rebuild-up after a pressure decrease, brake pressure is applied first at a steep and subsequently at a flatter gradient, this being achieved by a variable pulse (P1) and by short fixed pulses (P2) succeeding one another at a large interval. Circuits are provided rendering dependent the pulse and pulse break times (T.sub.1, T.sub.2, T.sub.k) determining the pressure build-upon the duration of the pressure build-up (T.sub.1) during the steep-rise build-up in the preceding cycle,on the duration (T.sub.1 +nT.sub.2) of the entire pressure build-up in the preceding cycle, andon the duration (T.sub.o) of the preceding pressure decrease, with the pulse times being so dimensionedthat, at a constant coefficient of friction and at a constant static pressure, the locking limit of the wheel is rereached after a predetermined period of time or after a predetermined pulse number. The duration of the variable and of the fixed pressure build-up pulses is computed from the pressure build-up of the preceding pressure or determined from a stored Table.
Abstract:
A method and electronic circuit for use in an automotive vehicle brake system with electronic anti-lock control and/or traction slip control is equipped with circuits for identifying a state of vehicle cornering. The slip of the controlled wheel during the time intervals in which the wheel is running stably, and the control frequency or the duration of the control cycles are measured. If the wheel slip exceeds a constant predetermined limit value or a value which depends on the velocity of the vehicle, and if, simultaneously, the control cycles are short on identification of vehicle cornering and corresponding signal is generated.
Abstract:
A method of monitoring a brake system which is equipped with anti-lock control (ABS) and a system for electronic control of brake force distribution (EBV). The system includes two brake circuits in a black/white brake circuit split-up, the EBV function or control is principally released only when the vehicle deceleration exceeds a predetermined limit value (GWN). To identify a front-axle brake circuit failure, acceleration criteria, i.e., criteria responsive to the acceleration behavior of the vehicle wheels, are predetermined and monitored. Further, slip range monitoring in conjunction with acceleration range monitoring is performed. Upon `detection` of an acceleration criterion or when a limit value (GW2) predetermined as an acceleration criterion is exceeded, and/or upon `detection` of values which are outside the slip range (GW1) or the acceleration range (GW5), a `suspected` front-axle brake circuit failure is signaled, and intervention into the electronic control of the brake force distribution (EBV) is performed.
Abstract:
For the reduction of disadvantageous effects of engine stall torques on the braking behavior of a vehicle which is equipped with a brake unit having an anti-lock control system, the brake slip of the driven wheels is monitored independently of any actuation of the brake. In the event of a rotational behavior of the driven wheels which is typical of the effect of engine stall torques, in particular in the event of a brake slip at the driven wheels exceeding a limit value, brake pressure existing in the wheel brakes of the driven wheels is maintained constant or reduced, or, if the braking action has not yet commenced, the supply of brake pressure into the wheel brakes of the driven wheels is prevented.
Abstract:
A circuit configuration for an anti-lock brake system, including a master cylinder (1) with a travel switch (27, 27') and an electromotively (31, 31') driven hydraulic pump (32, 32'), disposes of a "pump control" (45) which switches on the drive motor (31, 31') of the hydraulic pump (32, 32') in dependence on the vehicle deceleration and on the pressure fluid requirement during an anti-lock controlled braking operation, or on corresponding criteria and test results.
Abstract:
A method for controlling an anti-lock brake system for automotive vehicles with all-wheel drive. Electric signals representative of the rotational behavior of the wheels are generated and logically combined. Upon the occurrence of a tendency to lock, the braking pressure is modulated wherein the instantaneous wheel slip, wheel acceleration and wheel deceleration are evaluated as control criteria and the individual wheel speed (v.sub.R) is compared in each case with a vehicle reference speed (v.sub.REF) which serves as a reference value for the modulation of braking pressure. In the event of a wheel rotational behavior that is typical of spinning and that shows in the rise of the vehicle reference speed (v.sub.REF) in excess of the actual vehicle speed (v.sub.FZG), the control concept is modified until a specific point of time by deleting the instantaneous wheel slip as a control criterion for this phase of spinning and by the brake slip control becoming dependent on solely wheel acceleration or wheel deceleration.
Abstract:
A circuit arrangement which is provided for a vehicle with an electronic anti-lock control system and is used to enhance the driving stability in critical driving situations includes circuits for the individual control of the braking pressure on the front wheels and for limiting the yawing torque following braking maneuvers on .mu.-split road surfaces. In defined, especially critical driving situations, in particular during driving maneuvers with an abrupt change in .mu.-conditions or during braking maneuvers on .mu.-patch road surfaces, when predetermined criteria for a critical driving situation of this type are satisfied, a special control is started to bring about braking pressure reduction on the HM-wheel for a predetermined period which is responsive to vehicle speed.
Abstract:
The invention provides a method of detecting a defective condition on a pressure switch arrangement which at least assumes a defective condition on the said pressure switch assembly whenever a signal arrives at an input of an electronic computing unit which cannot be associated either to the opened or to the closed condition of the pressure switch. Moreover, a defective condition on the pressure switch arrangement mounted in the brake system of a vehicle is assumed, once the pressure switch signal refers to an actuated brake although the vehicle is significantly accelerated. Conversely, a defective condition is also assumed if the vehicle significantly decelerates although the pressure switch signal refers to a lack of brake pressure. Also, an appropriate pressure switch arrangement is provided which, with the pressure switch closed, generates a rectangular signal and, with the pressure switch opened, generates a high level on the input II of an electronic computing unit. With an incoming low level, an error on the pressure switch arrangement is assumed.