Traction control apparatus

Traction control means adapted for use with a vehicle including at least one pair of driven wheels arranged on opposite sides of the vehicle;

• means including a differential mechanism for driving said driven wheels;
• a plurality of wheel brake means associated with each of said driven wheels, respectively;
• a plurality of brake-operating means for operating each of said wheel brake means, respectively, each of said brake operating means including a housing, a brake diaphragm (24, 24') mounted in said housing to define first and second compartments, said brake diaphragm being operable between brake-engaged and brake-released positions in which the associated brake means are in braking and released conditions, respectively;
• a plurality of brake-locking means associated with each of said brake-operating members, respectively, each of said brake-locking means including brake spring means (28, 28') for normally biasing the associated brake diaphragm toward its brake engaged position;
• and a plurality of disabling means associated with said brake-locking means, respectively, each of said disabling means including a spring diaphragm (22, 22') mounted in the associated housing to define third and fourth compartments in one of which the associated spring means is mounted, said spring diaphragm being operable between spring-enabling and spring-disabling positions in which said spring means is activated and de-activated relative to said brake diaphragm, respectively;
• said vehicle braking system further including first conduit means (46a, 46b) for supplying pressure fluid simultaneously to one of said first and second compartments of each of said housings to position all of said brake diaphragms in their brake-engaged positions, and second conduit means (54a, 54b) for supplying pressure fluid simultaneously to one of said third and fourth compartments of each of said housings to position all of said spring diaphragms in their disabling positions;
• said traction control means including
• a. a plurality of velocity sensing means (60, 62) for generating signal voltages which are a function of the rotational velocities of said driven wheels, respectively;
• b. voltage comparison circuit means (64) for comparing said signals voltages of said one pair of driven wheels and for producing a control signal when the rotational velocity of one driven wheel of said pair exceeds that of the other driven wheel of said pair by a predetermined value;
• and
• c. solenoid valve means responsive to said control signal for placing in the spring enabling position only that spring diaphragm which is associated with the driven wheel having the greater rotational velocity, thereby to effect selective braking of the faster wheel of said one wheel pair, said solenoid valve means including a plurality of solenoid valves (56, 58) connected in said second conduit means for interrupting the supply of pressure fluid to, and for simultaneously venting, the said one of said third and fourth compartments of that housing which is associated with the driven wheel having the greater rotational velocity.

Traction control means adapted for use with a vehicle braking system including at least one pair of driven wheels connected by a differential mechanism, and a plurality of wheel brake means associated with said driven wheels, respectively, each of said wheel brake means including diaphragm operable between brake-engaged and brake-released positions, and brake spring means (26, 26') biasing the brake diaphragm toward its brake-released position;

• said traction control system comprising
• a. a plurality of locking spring means (28, 28') normally biasing each of said brake diaphragms toward its brake-engaged position;
• b. means including a plurality of spring diaphragms (22, 22') associated with said locking spring means, respectively, each of said spring diaphragms being operable between enabling and disabling positions in which the associated locking spring means is in operative and inoperative conditions relative to said brake diaphragm, respectively, and a plurality of housings associated with said wheel brake means, respectively, each of said housings containing superimposed upper and lower diaphragm chambers, said spring and brake diaphragms being mounted in said upper and lower chambers, respectively, thereby to define upper and lower compartments in each of said chambers, said locking spring being a compression spring mounted in the upper compartment of the upper chamber for biasing said spring diaphragm from the spring-disabling position downwardly toward the spring-enabling position, said brake diaphragm spring being mounted in the lower compartment of the lower chamber for biasing the brake diaphragm from the brake-engaged position upwardly toward the brake-released position, and pusher rod means (30, 30') slidably extending through an opening contained in the housing wall which separates the upper and lower chambers, said pusher rod means being operable by said spring diaphragm to force said brake diaphragm toward the brake-engaged position when the spring diaphragm is in the spring-enabling position;
• c. first conduit means (46a, 46b) for simultaneously connecting the upper compartments of the lower chambers of the housing with a pressure fluid source to lower the brake diaphragms toward their brake-engaged positons;
• d. second conduit means (54a, 54b) for simultaneously connecting the lower compartments of the upper chambers of said housings with a pressure fluid source, thereby to raise the spring diaphragms associated therewith to their spring-disabling positions;
• e. a plurality of velocity sensing means for generating signal voltages which are a function of the rotational velocities of said driven wheels, respectively;
• f. voltage comparison circuit means for comparing said signal voltages and for producing a control signal when the rotational velocity of one driven wheel exceeds that of the other driven wheel by a predetermined value;
• and
• g. means responsive to said control signal for placing in the enabling position the spring diaphragm associated with the driven wheel having the greater rotational velocity, thereby to automatically brake the faster driven wheel, said control signal responsive means including valve means (56, 58) connected in said second conduit means for venting and interrupting the supply of pressure fluid to the lower compartment of the upper chamber of the housing associated with the faster driven wheel, whereby the locking spring of that housing causes the brake diaphragm associated therewith to be lowered to its brake-engaged position effect braking of the faster driven wheel.

A traction control system for a vehicle including at least one pair of driven wheels (2, 4) connected by differential means (6), and separate wheel brake means (8, 10) associated with said driven wheels, respectively, comprising

• a. a pair of spring means (28, 28') normally operating both said wheel brake means to a brake-engaged condition, respectively;
• b. means (22, 22', 50) for normally de-activating both said spring means relative to their respective wheel brake means;
• c. a plurality of velocity sensing means (60, 62) for generating signal voltages which are a function of the rotational velocities of said driven wheels, respectively;
• d. voltage comparison means (64) for comparing said signal voltages of said driven wheels, respectively, and for producing a control signal when the rotational velocity of one driven wheel exceeds that of the other driven wheel by a predetermined value;
• and
• e. means (56, 58) responsive to said control signal for activating only that spring means which is associated with the driven wheel having the faster rotational velocity, thereby to effect braking of the faster driven wheel, whereby driving torque is transferred through said differential means to the driven wheel having the lower rotational velocity.