Anti-skid braking systems

Claim 2

In a method for the anti-skid braking of a vehicle wheel, in which the braking fluid pressure is decreased and increased repeatedly during one braking operation in accordance with changes in the dynamic condition of the wheel, the improvement that, if the peak value of the braking fluid pressure is below a threshold, the braking fluid pressure may decrease to a zero value in a single phase substantially instantaneously, while, if the peak value of the braking fluid pressure is above the threshold, the braking fluid pressure may decrease toward a zero value in two phases, a first phase of a fixed decrement of pressure proportional to said peak value substantially instantaneously and a second phase at a comparatively gradual rate the extent of the fluid pressure decrease being dependent on the fluid pressure drop required to effect a change in the dynamic condition of the wheel.

Claim 3

In a method for the anti-skid braking of a vehicle wheel, in which the braking fluid pressure is decreased and increased repeatedly during one braking operation in accordance with changes in the dynamic condition of the wheel, the improvement that, if the peak value of the braking fluid pressure is below a threshold, the braking fluid pressure may decrease to a zero value in a single phase substantially instantaneously, while, if the peak value of the braking fluid pressure is above the threshold, the braking fluid pressure may decrease toward a zero value in two phases, a first phase of a fixed decrement of pressure proportional to said peak value substantially instantaneously and a second phase at a comparatively gradual rate the extent of the fluid pressure decrease being dependent on the fluid pressure drop required to effect a change in the dynamic condition of the wheel.

Claim 4

In a method for the anti-skid braking of a vehicle wheel, in which the braking fluid pressure is decreased and increased repeatedly during one braking operation in accordance with changes in the dynamic condition of the wheel, the improvement that, if the peak value of the braking fluid pressure is below a threshold, the braking fluid pressure may decrease to a zero value in a single phase substantially instantaneously, while, if the peak value of the braking fluid pressure is above the threshold, the braking fluid pressure may decrease toward a zero value in two phases, a first phase of a fixed decrement of pressure proportional to said peak value substantially instantaneously and a second phase at a comparatively gradual rate the extent of the fluid pressure decrease being dependent on the fluid pressure drop required to effect a change in the dynamic condition of the wheel.

Claim 5

The method of claim 1 in which, if in the two-phase pressure decrease the braking fluid pressure falls below the threshold during the first phase, the second phase may be followed by a third phase in which the pressure may decrease substantially instantaneously to a zero value.

Claim 6

In an apparatus for the anti-skid braking of a vehicle wheel, including a source of fluid pressure, a brake cylinder, a tube connecting the source to the brake cylinder, discharge means connected to the brake cylinder and an anti-skid apparatus connected in the tube and responsive to changes in the dynamic condition of the wheel for repeatedly causing a decrease and an increase in the pressure in the brake cylinder during a braking operation, the improvement that the apparatus further includes means connected to the discharge means and responsive to the peak value of the braking pressure for discharging the braking pressure substantially instantaneously in a single phase if the peak value is below a threshold, and for discharging the braking pressure in two phases, in a first phase of a fixed decrement of pressure proportional to said peak value substantially instantaneously and in a second phase at a comparatively gradual rate, if the peak value is above the threshold and the anti-skid apparatus does not increase the pressure prior to the initiation of said second phase, said means responsive to the peak value of the braking pressure including: a. a selector valve having a control port, an inlet connected to the discharge means, a first outlet leading to exhaust and a second outlet leading to an absorber, the absorber communicating with a restrictor which leads to exhaust; b. pressure-retaining means having an inlet connected to a point in the tube downstream of the anti-skid apparatus, and an outlet connected to the control port of the selector valve; c. the selector valve connecting its inlet to its first outlet if the pressure in the control port is below the threshold, and connecting its inlet to its second outlet if the pressure in the control port is above the threshold.

Claim 7

In an apparatus for the anti-skid braking of a vehicle wheel, including a source of fluid pressure, a brake cylinder, a tube connecting the source to the brake cylinder, discharge means connected to the brake cylinder and an anti-skid apparatus connected in the tube and responsive to changes in the dynamic condition of the wheel for repeatedly causing a decrease and an increase in the pressure in the brake cylinder during a braking operation, the improvement that the apparatus further includes means connected to the discharge means and responsive to the peak value of the braking pressure for discharging the braking pressure substantially instantaneously in a single phase if the peak value is below a threshold, and for discharging the braking pressure in two phases, in a first phase of a fixed decrement of pressure proportional to said peak value substantially instantaneously and in a second phase at a comparatively gradual rate, if the peak value is above the threshold and the anti-skid apparatus does not increase the pressure prior to the initiation of said second phase, said means responsive to the peak value of the braking pressure including: a. a selector valve having a control port, an inlet connected to the discharge means, a first outlet leading to exhaust and a second outlet leading to an absorber, the absorber communicating with a restrictor which leads to exhaust; b. pressure-retaining means having an inlet connected to a point in the tube downstream of the anti-skid apparatus, and an outlet connected to the control port of the selector valve; c. the selector valve connecting its inlet to its first outlet if the pressure in the control port is below the threshold, and connecting its inlet to its second outlet if the pressure in the control port is above the threshold.

Claim 8

The apparatus of claim 3, in which the pressure-retaining means includes a check valve.

Claim 9

The apparatus of claim 4, in which the pressure-retaining means includes a restrictor bypassing the check-valve.