Electro-pneumatic control system

Claim 2

In a vehicle brake actuation system having a fluid pressure source and brake actuators operated by fluid pressure: an operator-operated brake control valve communicated with said fluid pressure source; first means for generating a first signal proportional to the difference between the pressure levels at said brake control valve and the pressure level delivered to said brake actuators; second means for comparing said first signal with a predetermined reference signal and generating a second signal if said first signal is greater than the reference signal and terminating said second signal if the first signal again drops below said reference signal; and third means responsive to said second signal for initiating communication between said brake actuators and said pressure source if the pressure level delivered to the brake actuators is less than the pressure level at the brake control valve and venting said brake actuators if the pressure level in the brake actuators is greater than the pressure level at said brake control valve.

Claim 3

In a vehicle brake actuation system having a fluid pressure source and brake actuators operated by fluid pressure; an operator-operated brake control valve communicated with said fluid pressure source; control means for comparing the fluid pressure level at the brake control valve and the pressure level delivered to the brake actuators and generating a first error signal if the pressure leVel at the brake control valve exceeds the pressure level delivered to said actuators by more than a predetermined amount and terminating said first error signal if the pressure differential of the brake control valve over the brake actuators decreases to a value less than the predetermined amount, said control means including means for generating a second error signal if the pressure level delivered to said brake actuators exceeds the pressure level at said brake control valve by more than a predetermined amount and terminating said second error signal if the pressure differential of the brake actuators over that of the brake control valve decreases to a value less than the predetermined amount; and valve means responsive to said first error signal to communicate said brake actuators with said fluid pressure source and responsive to said second error signal to vent said brake actuators.

Claim 4

In a vehicle brake actuation system having a fluid pressure source and brake actuators operated by fluid pressure; an operator-operated brake control valve communicated with said fluid pressure source; control means for comparing the fluid pressure level at the brake control valve and the pressure level delivered to the brake actuators and generating a first error signal if the pressure leVel at the brake control valve exceeds the pressure level delivered to said actuators by more than a predetermined amount and terminating said first error signal if the pressure differential of the brake control valve over the brake actuators decreases to a value less than the predetermined amount, said control means including means for generating a second error signal if the pressure level delivered to said brake actuators exceeds the pressure level at said brake control valve by more than a predetermined amount and terminating said second error signal if the pressure differential of the brake actuators over that of the brake control valve decreases to a value less than the predetermined amount; and valve means responsive to said first error signal to communicate said brake actuators with said fluid pressure source and responsive to said second error signal to vent said brake actuators.

Claim 5

The invention of claim 2: said control means including first means for generating a first intermediate signal proportional to the difference between the pressure level at the brake control valve and the pressure level delivered to the brake actuators and second means for generating a second intermediate signal proportional to the difference between the pressure level delivered to said brake actuators and the pressure level at said brake control valve.

Claim 6

The invention of claim 3: said control means further including a first comparator for comparing said first intermediate signal with a first reference signal and generating said first error signal if the first intermediate signal exceeds the first reference signal and a second comparator for comparing said second intermediate signal with a second reference signal and generating said second error signal if the second intermediate signal is greater than the second reference signal.

Claim 7

The invention of claim 3: said control means including first pressure responsive means at said brake valve for generating an electrical signal proportional to the pressure level at said brake valve; and second pressure responsive means for generating an electrical signal proportional to the pressure level delivered to said brake actuators; said electrical signal generated by said first and second pressure responsive means being transmitted to said first means and to said second means.

Claim 8

The invention of claim 5: said first and second pressure responsive means being piezo-resistive pressure transducers.

Claim 9

The invention of claim 2; and a relay valve for controlling fluid communication between the pressure source and the brake actuators; said brake control valve being operable to transmit pressure to said relay valve to actuate the latter to initiate fluid communication between the brake actuators to the pressure source when the brake control valve is applied and to release said relay valve to vent said brake actuators when the brake control valve is released; said valve means responding to said first error signal to actuate the relay valve to thereby initiate communication between said brake actuators and the pressure source and to said second error signal to release said relay valve to vent said brake actuators.

Claim 10

The invention of claim 7: said valve means including a first electrically operated valve responsive to said first error signal to terminate fluid communication between the relay valve and the brake control valve and to initiate fluid communication between the pressure source and the relay valve to actuate the latter to admit fluid pressure to the brake actuators and a second electrically operated valve responsive to said second error signal to release said relay valve to vent said brake actuators.

Claim 11

The invention of claim 2: a warning device mounted in the operator''s compartment of the vehicle; and fail-safe means for actuating said warning device when a malfunction prevents satisfactory operation of said control means.

Claim 12

The invention of claim 4: said controL means further including a device responsive to the output of one of said comparators for generating a signal for a predetermined time period, the length of said time period being independent of fluctuations in the value of said error signals and first gating means inhibiting the output of said one comparator after the signal generated by said device expires.

Claim 13

The invention of claim 10: said control means further including a device responsive to the output of the other comparator for generating a signal for a predetermined time period, the length of said time period being independent of fluctuations in the value of said error signals, and second gating means inhibiting the output of the other comparator after the signal generated by said device expires.

Claim 14

The invention of claim 4: said control means further including a device responsive to the output of said first comparator for generating a signal for a predetermined time period, a window comparator for comparing said first intermediate signal with a pair of reference signals and generating an output signal if the first intermediate signal is greater than one of the reference signals but less than the other reference signal, and gating means inhibiting the output of said first comparator unless said window comparator and said device produces an output signal.

Claim 15

The invention of claim 10; and a warning device mounted in the operator''s compartment of the vehicle; said control means further including means for actuating said warning device if the output of the corresponding gating means is not equal to the output of said one comparator.

Claim 16

The invention of claim 11; and a warning device mounted in the operator''s compartment of the vehicle; said control means further including means for actuating said warning device if the output of said first gating means is not equal to the output of said one comparator and if the output of said second gating means is not equal to the output of the other comparator.

Claim 17

The invention of Claim 4: a warning device mounted in the operator''s compartment of the vehicle; and first and second power amplifiers for amplifying said first and second error signals respectively; said control means further including means for actuating said warning device when either of said first or second power amplifiers malfunction.

Claim 18

In a tractor-trailer breaking system having a fluid pressure source and brake actuators operated by fluid pressure: a first fluid reservoir carried by said tractor; a second fluid reservoir carried by said trailer; a relay valve carried by said trailer for actuating the brake actuators carried by the trailer, said relay valve having a primary section and a delivery section, said primary section being responsive to fluid pressure to cause said delivery section to communicate said second reservoir with the brake actuators carried by the trailer; electrically operated valve means for controlling fluid communication between said primary section and said second reservoir and between said primary section and the atmosphere; an operator-operated brake control valve communicated to said first reservoir for actuating the brakes of the tractor and trailer; control means for comparing the fluid pressure level at the brake control valve and the fluid pressure level at the brake actuators carried by the trailer and generating a first error signal if the pressure level at the brake control valve exceeds the pressure level delivered to said trailer actuators by more than a predetermined amount and generating a second error signal if the pressure level delivered to said trailer brake actuators exceeds the pressure level at said control valve by more than a predetermined amount; said electrically operated valve means being responsive to said first error signal to communicate said primary section of the relay valve with said second reservoir to thereby cause said delivery section to communicate saiD second reservoir with the brake actuators carried by the trailer and responsive to said second error signal to vent said primary section to atmosphere to thereby permit said delivery section to also vent said trailer brake actuators to atmosphere.

Claim 19

In a tractor-trailer breaking system having a fluid pressure source and brake actuators operated by fluid pressure: a first fluid reservoir carried by said tractor; a second fluid reservoir carried by said trailer; a relay valve carried by said trailer for actuating the brake actuators carried by the trailer, said relay valve having a primary section and a delivery section, said primary section being responsive to fluid pressure to cause said delivery section to communicate said second reservoir with the brake actuators carried by the trailer; electrically operated valve means for controlling fluid communication between said primary section and said second reservoir and between said primary section and the atmosphere; an operator-operated brake control valve communicated to said first reservoir for actuating the brakes of the tractor and trailer; control means for comparing the fluid pressure level at the brake control valve and the fluid pressure level at the brake actuators carried by the trailer and generating a first error signal if the pressure level at the brake control valve exceeds the pressure level delivered to said trailer actuators by more than a predetermined amount and generating a second error signal if the pressure level delivered to said trailer brake actuators exceeds the pressure level at said control valve by more than a predetermined amount; said electrically operated valve means being responsive to said first error signal to communicate said primary section of the relay valve with said second reservoir to thereby cause said delivery section to communicate saiD second reservoir with the brake actuators carried by the trailer and responsive to said second error signal to vent said primary section to atmosphere to thereby permit said delivery section to also vent said trailer brake actuators to atmosphere.

Claim 20

The invention of claim 16: said brake control valve being communicated to said primary section to actuate said relay valve when a malfunction prevents normal operation of the electrically operated valve means; said electrically operated valve means terminating fluid communication between the brake valve and the primary section when communication between said second reservoir and said primary section is initiated.

Claim 21

In a vehicle brake actuation system having a fluid pressure source and brake actuators operated by fluid pressure: an operator-operated brake control valve communicated with said fluid pressure source; control means for comparing the difference between said fluid pressure level at the brake control valve and at said actuators with a first reference value and generating a first error signal if said difference exceeds said reference value and terminating said first error signal when said difference drops below said predetermined amount, said control means comparing the difference between the fluid pressure level at said control valve with a second reference value and generating a second error signal if said last-mentioned difference exceeds said second reference value and terminating said second error signal when said last-mentioned difference drops below said second reference value; and valve means responsive to said first error signal to communicate said actuators with said fluid pressure source and responsive to said second error signal to vent said actuators.

Claim 22

In a vehicle brake actuation system having a fluid pressure source and brake actuators operated by fluid pressure: an operator-operated brake control valve communicated with said fluid pressure source; control means for comparing the difference between said fluid pressure level at the brake control valve and at said actuators with a first reference value and generating a first error signal if said difference exceeds said reference value and terminating said first error signal when said difference drops below said predetermined amount, said control means comparing the difference between the fluid pressure level at said control valve with a second reference value and generating a second error signal if said last-mentioned difference exceeds said second reference value and terminating said second error signal when said last-mentioned difference drops below said second reference value; and valve means responsive to said first error signal to communicate said actuators with said fluid pressure source and responsive to said second error signal to vent said actuators.