Torque sensing braking controller for brakes

A torque sensing braking controller for a drum brake, comprising a wheel cylinder housing fixedly mounted between adjacent ends of a pair of brake shoes and including two differential area pistons each having an enlarged diameter portion and operatively engaging an associated brake shoe, both pistons disposed within a bore of the wheel cylinder housing such that the enlarged diameter portions of the respective pistons and housing define first and second chambers each disposed on opposite sides of the enlarged diameter portions of the respective pistons, each piston having an interior opening receiving first valve means therein, communication passages between each of said first and second chambers with the interior opening disposed between the passages, resilient means between said brake shoes for biasing said brake shoes radially inwardly, and second valve means disposed between opposite adjacent ends of said brake shoes, the second valve means comprising a differential area piston device having opposite ends operatively engaged by respective ends of said shoes, the second valve means communicating with each of the first chambers in said wheel cylinder housing, communication of pressurized fluid to the second valve means and wheel cylinder housing effecting outward displacement of said differential area pistons to engage the brake shoes with the drum and retard rotation thereof, the outward displacement of said pistons causing the transfer of fluid from said first chambers to said second chambers and the pressurized fluid effecting outward displacement of the pistons independently of any output pressure from the second valve means, a sudden decrease in braking torque caused by cessation of drum rotation causing displacement of said piston device and the communication of an output pressure to each of the first chambers of said wheel cylinder housing to effect closure of said first valve means and increase the pressure in the first chambers to oppose the outward displacement of said pistons by said pressurized fluid, the increase of the pressure in the first chambers decreasing the force exerted by the pistons against the respective brake shoes such that the rotating drum is released for rotation.

A torque sensing braking controller for a servo brake, comprising a pair of brake shoes carrying friction elements thereon and adapted to be driven into frictional engagement with a rotating drum disposed thereabout, a wheel cylinder housing disposed between adjacent ends of said brake shoes and including in a bore therein a pair of wheel cylinder pistons with a pressure chamber therebetween communicating with a master cylinder of the vehicle and each wheel cylinder piston operatively engaging one of said brake shoes, the wheel cylinder pistons comprising differential area pistons each having an enlarged diameter portion received within an enlarged diameter section of said bore, the enlarged diameter portion of each piston defining with the enlarged diameter section a first and second chamber disposed on opposite sides of the enlarged diameter portion, the wheel housing further including a second bore having a control piston therein and receiving pressurized fluid from said master cylinder, the control piston biased by spring means and operatively engaging one of said brake shoes, the second bore communicating with a third bore containing valve means therein, the valve means communicating with the first and second chambers of the wheel cylinder housing to permit transfer of fluid therebetween when the respective pistons are displaced, the communication of pressurized fluid from said master cylinder to the pressure chamber effecting outward displacement of said pistons to effect engagement of the friction elements with the rotating drum such that braking torque is transmitted by one of said brake shoes to said control piston, the pressurized fluid from the master cylinder expanding the pistons independently of any pressure increase effected by the control piston, the pressurized fluid and spring means acting upon said control piston in opposition to said braking torque which causes said control piston to be displaced, a sudden decrease in braking torque resulting from the brake shoes causing said drum to cease rotation permitting the control piston to be displaced in an opposite direction and communicate fluid pressure to said valve means to cause said valve means to close and permit the fluid pressure to be communicated only to the first chambers of said wheel cylinder housing in opposition to the outward displacement of the pistons by the pressurized fluid from the master cylinder, the fluid pressure from the control piston causing said pistons to decrease the force exerted upon the brake shoes such that the rotating drum is permitted to recommence rotation.

A torque sensing braking controller for a disc brake operating responsively to a master cylinder, comprising a caliper, a torque support plate fixed to a vehicle and slidably supporting thereon the caliper, the caliper comprising a housing having a first bore therein receiving a differential area piston, the first bore including an enlarged bore section and the piston having an enlarged diameter portion received in the enlarged bore section such that the piston and housing define first and second chambers on opposite sides of said enlarged diameter portion, a pair of friction elements disposed on opposite sides of a rotor operatively attached to a vehicle wheel, one friction element engaged by said piston and the other friction element engaged by the caliper, a control piston disposed within a second bore within said caliper, the control piston biased by resilient means in one direction into engagment with connection means operatively connected to at least one of said friction elements, the second bore communicating with said master cylinder and with valve means disposed in a third bore within said caliper, the third bore communicating with each of said first and second chambers, the communication of pressurized fluid from said master cylinder to the first bore biasing the piston outwardly into engagement with the one friction element independently of any pressure received from said control piston and causing said friction element to engage the rotor, reaction forces causing the caliper to be displaced and cause the other friction element to engage the opposite side of the rotor in order to retard rotation thereof, braking torque causing said friction elements to be circumferentially displaced and cause the connection means to displace the control piston against the resilient means, a sudden cessation of rotation of said rotor effecting a sudden decrease in braking torque exerted against said control piston and permitting the control piston to be displaced in an opposite direction to cause the communication of an output pressure from said control piston to said valve means, the output pressure causing said valve means to close and prevent fluid transfer between said first and second chambers and permit communication of the output pressure only to said first chamber to oppose displacement of the differential area piston by the pressurized fluid from the master cylinder, the increase in pressure in the first chamber causing a reduction in braking force exerted by the differential area piston on the one friction element so that the rotor may recommence rotation.