摘要:
An anti-skid brake conrol system includes a sensor which produces a signal proportional to the acceleration of a braked wheel and a comparator that responds to the acceleration signal by producing a signal which undergoes a step change at set acceleration levels so as to divide successive deceleration/acceleration cycles into successive acceleration periods separated by intermediate periods. The output of the comparator is integrated to produce an output signal which changes in a progressive manner in one sense during each acceleration period and in the opposite sense during each intermediate period so as to vary in accordance with surface friction conditions. The output signal is used to vary a control parameter or function within the system in accordance with the surface friction conditions. The integrator may comprise a capacitor which is discharged so that its potential falls during each acceleration period from an initial predetermined level and is then charged during each intermediate period so that its potential rises, the charging rate being increased at a predetermined threshold potential below which low friction conditions are signalled.
摘要:
An anti-lock brake control system for a vehicle with braked wheels comprises a sensor to produce a signal proportional to the deceleration/acceleration of the braked wheel, a deceleration sensing switch to respond to the deceleration/acceleration signal by producing a brake pressure release pulse when deceleration of the wheel exceeds a predetermined threshold level, a charge storage device which is adapted so that it charges in a predetermined progressive manner while the brake pressure release pulse is produced and discharges at a predetermined decay rate, a comparator that compares the potential on the charge storage device with a reference potential and produces an extension brake pressure release pulse according to their relative values, and apparatus to vary one of said potentials in a manner dependent on acceleration of the wheel above a preset acceleration threshold so that the extension brake pressure release pulse is terminated by increasing wheel acceleration. In one embodiment, the apparatus varies the reference potential so that the change of the reference potential with increasing acceleration is in the same sense as the change in the potential on the charge storage device when charging, the comparator producing said extension pulse only while the potential on the charge storage device exceeds the fixed reference potential. In another embodiment, the apparatus varies the potential on the charge storage device by discharging the latter after it has been charged from a fixed starting potential, the comparator producing an extension pulse as soon as the potential on the charge storage device exceeds a fixed reference potential and terminating the extension pulse once the potential on the charge storage device falls to a fixed terminating potential above the fixed reference potential.
摘要:
In an anti-lock brake control system for a vehicle with braked wheels, a brake pressure release pulse is produced in a manner dependent on wheel deceleration and is processed so that it cannot exceed a preset maximum length and is spaced from any other brake pressure release pulses by a preset inhibit period so that brake pressure release pulses cannot be produced above a certain maximum repetition frequency. A deceleration sensing switch produces an output pulse, and a pulse circuit is triggered by the leading edge of the output pulse to commence said brake pressure release pulse, and is reset by the lagging edge of said output pulse to terminate said brake pressure release pulse. A pulse timing circuit is also triggered by the leading edge of said output pulse and operates to terminate said brake pressure release pulse after said predetermined maximum duration if it has not been terminated already. An inhibit timing circuit is triggered by the brake pressure release pulse from the pulse circuit, and while triggered, produces an inhibit pulse that prevents the pulse circuit from being re-triggered, the inhibit timing circuit resetting to remove said inhibit pulse after expiry of said preset inhibit period following termination of the brake pressure release pulse.
摘要:
An electronically controlled braking system wherein improved braking distribution in a multi-axle vehicle is achieved by making allowance for sources of background braking by assessing through measurement the total background braking force and assigning this in a predetermined proportion between the vehicle axles.
摘要:
An electronic braking system for wheeled vehicles comprising an electronic controller which produces, in response to driver braking demands, electronic signals for controlling the braking pressures applied to the vehicle wheels from a source of braking pressure. The system includes a second, back-up braking pressure source which can be selected when required, and means for switching over from the first-mentioned normal source of braking pressure to the back-up pressure source at selected occasions when the vehicle is being braked and has come to rest, provided that the prevailing driver's braking demand is above a predetermined minimum threshold. A test is then performed on the braking pressure signals generated by the system while it is energized by the back-up source and a warning signal is generated if the back-up source is found to be faulty.
摘要:
A dual computer cross-checking system includes a control computer for controlling a process in accordance with input data and a monitoring computer. The two computers are interconnected to exchange check data on a cyclic basis, each computer carrying out a number of processing operations on the received check data before transmitting the data thus processed to the other computer. In addition, each computer checks the received check data against an expected value. An error condition is detected if the result of at least one of these comparisons is found to be incorrect.
摘要:
An anti-skid braking system for a vehicle comprising a supply of fluid for actuating a plurality of wheel brakes, a skid control unit interposed between the fluid supply and the brakes, sensors to detect the skidding of a plurality of wheels and actuating means responsive to skid signals from the sensors and adapted to actuate the skid control unit to relive the fluid pressure at the brake of the wheel at impending lock by means of a plurality of successive first brake release periods. In order to reduce yawing, when an impending skid condition is detected at one wheel, the skid control unit is arranged to induce second, shorter brake release periods in one or more of the brakes of the wheels not at impending lock.
摘要:
An electronically controlled braking system for a vehicle in which vehicle load measurements, made dynamically, as used to modify the braking demand, individually for each axle of the vehicle and in which, under predetermined conditions of vehicle speed, braking level and operating gradient, the deceleration error formed between braking demand by the driver and measured actual vehicle deceleration is used gradually, over a number of vehicle stops, to form an adaptive factor for correcting the braking demand in order to restore expected braking performance. No correction to the adaptive factor based on the deceleration error is made during a given stopping operation of the vehicle, but a summation of previous errors is arranged to cause a small increment in correction to be made after each stop until, over a number of vehicle stops, the error formed under the predetermined conditions falls to zero. Braking demands by the driver can be arranged to be compensated by introducing a demand offset dependent on the prevailing gradient on which the vehicle is operating.
摘要:
The invention provides a control system which predicts the brake re-apply point during a brake pressure release/re-apply cycle by measuring the duration of the synchronous running period, that period during which the wheel is decelerating at substantially the same rate as the vehicle. An increase in the synchronous running period above an optimum period is arranged to bring about an earlier re-application of the brakes in a cycle, and a decrease in the synchronous running period is used to effect a later re-application of the brakes. Various circuits are disclosed for detecting the duration of the synchronous running period. In a preferred circuit a track and store circuit compares an acceleration/deceleration signal with a stored signal whose amplitude follows that of the acceleration/deceleration signal, and the synchronous running period is taken to be the period between coincidences between the acceleration/deceleration signal and the stored signal. The timing of the brake re-apply signal is preferably controlled by varying a re-set threshold of a threshold switch responsive to wheel acceleration/deceleration.
摘要:
An anti-skid braking system including a plurality of independent solenoid energizing circuits which are controlled in accordance with the outputs of sensors on separate wheels of a vehicle, has a failure detection circuit comprising a timer triggered into operation each time any one of the solenoids is energized, and reset when a back e.m.f. generated by the deactivation of any solenoid is detected. If the timer is not reset within a fixed period the system is disabled and a warning lamp is energized. The system also includes a circuit utilizing the back e.m.f. signals for testing the system each time it is switched on.