GB732829A - Improvements in or relating to exhaust braking apparatus for motor vehicles driven by internal-combustion engines - Google Patents

Abstract

732,829. Regulating. stopping. CLAYTON DEWANDRE CO., Ltd. May 25, 1954 [June 9, 1953], No. 15873/53. Classes 7(5) and 7(6). [Also in Group XXXI] An exhaust braking apparatus comprises an exhaust throttle valve 12 which is closed for braking by fluid pressure or vacuum operated means 6 controlled by the accelerator pedal 16 or like engine control device. As shown the exhaust throttle valve 12 is situated in a tubular section 5 inserted in the exhaust pipe and is operated by a compressed-air motor 6 comprising a spring-loaded piston 8 connected to the throttle valve operating arm 11, the compressed air being supplied to one side of the piston 8 from a reservoir through a pipe 14 under the control of a valve 15 actuated by a solenoid 17 the circuit of which includes a micro-switch 20 operated by the engine accellerator pedal 16. On release of the pedal 16 the switch 20 is closed and the solenoid 17 operates the valve 15 to supply compressed air to the cylinder 7, whereby the valve 12 is closed for engine braking. The compressed air may also be tapped off at 23 to actuate a second piston device 22 which shuts off the fuel supply in a diesel engine during braking or, in an engine supplied by a carburetter, shuts off the combustible mixture supply and opens a subsidiary air valve in the induction system. The motor 6 is carried by a plate 9 bolted between the throttle section 5 and the exhaust manifold 4 and the initial position of the piston 8 is determined by an adjustable stop 21. To assist re-opening of the valve 12 by the spring 19, the piston 8 may be constructed as a differential piston both sides of which are supplied with compressed air to close valve 12, the supply to the larger face of the piston being cut off when the pedal 16 is depressed so that the supply to the smaller face assists the spring 19 to open the valve 12. The exhaust braking apparatus may be rendered inoperative by the opening of a master switch 25 in the circuit of the solenoid 17 ; alternatively a cock may be provided to cut off the supply of compressed air to the valve 15. In modifications the system is adapted for operation by vacuum from a vacuum reservoir or by hydraulic fluid from an accumulator and the piston-type motor 6 may be replaced by a diaphragm type motor.