Patent GB-742323-A (GB)
Title: Improvements in and relating to braking systems for vehicles driven by internal combustion engines
Inventor: SLEE ALFRED GRAHAM
IPC: F01L13/00
Filed: 1953-05-15
Abstract: 742,323. Regulating; starting and stopping oil engines; alarms. ASH & CO., Ltd., T., and BRITISH ELECTRIC TRACTION CO., Ltd. March 5, 1954 [May 15, 1953], No. 13631/53. Classes 7(2), 7(3), 7(5) and 7(6) [Also in Group XXXI] A butterfly valve in the exhaust pipe pivoted about an offset axis so that the exhaust gases tend to open the valve is closed for engine braking by a solenoid a the circuit of which is closed and opened by a switch i operated by the brake pedal so that the exhaust valve is closed before the friction wheel brakes are applied. In Fig. 1 the closing of the switch i causes a relay h to close the contacts c, c', which energizes both the solenoid a to close the exhaust brake valve and a solenoid k which moves the control rod of a fuel injection pump to the fuel cut-off position. A switch f, which normally short-circuits a resistance e, is opened a predetermined time after the.closing of the contacts c, c<SP>1</SP>, by a solenoid d in the circuit of the solenoid a whereby the resistance e is connected in this circuit to reduce the current therein. A separate manually operable switch may be provided for controlling the relay h and a solenoid connected in the brake valve circuit may prevent the engine throttle valve being opened during engine braking. The brake valve may be associated with a stop which prevents it closing completely alternatively it may close completely and a switch j may be provided which is opened when the clutch pedal is depressed to re-open the brake valve and prevent stalling of the engine. In a further modification stalling is prevented by a voltage-controlled switch in the dynamo circuit which breaks the brake valve circuit when the voltage drops below a predetermined value at low engine speeds. The electrical relay h may be replaced by pneumatic or hydraulic relay means for controlling the brake valve circuit and a hand-operated lever may be provided in addition to the electrical means for closing the brake-valve. A tell-tale light or other warning device may be provided to indicate when the brake valve is closed. In a fuel-injection engine having a suction-type governor controlling the fuel injection pump, the brake valve solenoid a, Fig. 2, and the solenoid k for moving the pump control rod to cut-off positions are controlled by the brake-pedal switch i and by a switch m actuated by the intake pipe suction which operates the suction governor. At the beginning of braking the switches i and m are both closed to energize the solenoids a, k, but when the engine speed drops to idling the switch m opens to open the brake valve and restore the idling fuel supply and switch n may be closed to stop the engine. A plunger u<SP>1</SP>, Fig. 4, may be provided to prevent the pump control rod moving beyond the normal maximum supply position, which plunger is raised by a solenoid v, Fig. 2, in parallel with the engine starter solenoid y to bring a recess x opposite the rod w to permit the supply of excess fuel for starting. In a further embodiment the fuel pump control rod may be moved to cut-off position during engine braking by a plunger connected by a cable to the brake valve operating means. In a carburettertype engine, an extra air valve may be opened when the brake valve is closed to allow air to be drawn directly into the induction pipe.