US 4,393,447 A · Method and a circuit for controlling the pressure in wheel brake cylinders of fluid-operated vehicular brakes

Abstract

It is known that an output valve providing a pressure decrease in a wheel brake cylinder can be controlled by a pulse train which is variable in response to the acceleration or deceleration of the associated wheel. A disadvantage of such an arrangement is that a wheel at standstill will not be able--under certain circumstances--to accelerate again during a control cycle. Additionally, the wheel brake cylinder pressure may have been decreased to such an extent that the wheel will neither continue to decelerate, or accelerate sufficiently. According to the present invention the control behavior is improved in these critical cases by generating pulses proportional to wheel acceleration and to transmit an opening signal to the outlet valve upon cessation of the accelerating pulses. The opening signal is immediately switched off as soon as the acceleration pulses occur again.

Claims8

Dependent claims

In a method for controlling pressure in a wheel brake cylinder by a control pulse train proportional to acceleration or deceleration of an associated wheel controlling an outlet valve coupled to said cylinder, an improvement comprising the steps of:

monitoring said control pulse train during each control cycle;
generating at least one opening pulse for coupling to said outlet valve whenever, after a first predetermined time interval, said pulse train is absent;
and
stopping the generation of said opening pulse immediately upon re-occurrence of said pulse train.

1 more element

In an arrangement for controlling pressure in a wheel brake cylinder in response to control pulse trains proportional to acceleration and deceleration of an associated wheel, a circuit comprising:

an input terminal for each of said control pulse trains;
an output terminal coupled to an outlet valve coupled to said cylinder to control pressure in said cylinder;
a first OR gate having three inputs and an output, two of said three inputs each being coupled to a different one of said input terminals;
a counter including a first output, a clock input coupled to a clock and a reset input coupled to said output of said first OR gate, said counter continuously counting up in response to said clock to provide a first pulse train having a first repetition frequency at said first output whenever, after a first predetermined time interval, said control pulse trains are absent;
and
means to couple said first pulse train to said output terminal to control said outlet valve and to the third of said three inputs of said first OR gate to reset said counter.

3 more elements

Dependencies are inferred from the claim text.

Method and a circuit for controlling the pressure in wheel brake cylinders of fluid-operated vehicular brakes

Life of this patent

Method and a circuit for controlling the pressure in wheel brake cylinders of fluid-operated vehicular brakes

Life of this patent

Abstract

Claims8