Patent GB-816263-A (GB)
Title: Improvements relating to internal-combustion engine driving systems
IPC: F01L13/00
Filed: 1957-03-21
Abstract: 816,263. Controlling vehicles. VOITH G.m.b.H., J. M. March 21, 1957 [March 21. 1956], No. 9349/57. Class 79(5) [Also in Groups XXVII and XXIX] In an engine having an exhaust brake 5, Fig. 1, and driving through a transmission which has a hydraulic torque converter 33 for a lower working range and a mechanical or hydraulic coupling 34 for an upper working range, an overriding device renders the exhaust brake inoperative below a working speed which is above the lowest speed of changeover from the upper to the lower working range of the transmission to prevent stalling of the engine. In Fig. 1 the exhaust brake 5 is operated by fluid pressure applied to a piston 7 under the control of an electromagnetically operated valve 18 controlled by a foot-operated switch 8 and by a switch 11 constituing the overriding device. The pressure medium supplied through pipe 21 to operate the valve 5 simultaneously operates upon a piston 30 connected to the injection pump control rod 26, normally operated from accelerator pedal 27, to move the pump control lever from the idling position L to cut-off position S. The change-over of the transmission from the torque converter 33 to the friction clutch 34 is effected by pressure fluid supplied through pipe 42 to piston 41 under the control of a spring- loaded valve 38 which is actuated at a predetermined engine speed by a pressure proportional to engine speed set up in pipe 36 by an engine driven pump 35, the spring load of valve 38 and hence the speed at which changeover occurs being controlled by a cam 47 actuated by the accelerator pedal 27. When the accelerator pedal is released and the brake pedal 8 operated whereby the exhaust brake 5 is operated and the fuel supply cut off, the valve 38 is set so that the transmission changeover occurs at idling speed. The spring-load of the over-riding switch 11, operated by the pressure from pipe 36, is set so that the switch 11 opens to cancel the exhaust braking and restore the idling fuel supply at a speed slightly above idling speed. The speed responsive device 36 may comprise an engine driven electric generator. In Fig. 3 the transmission comprises a hydraulic torque converter 33 and hydraulic coupling 34, the changeover being controlled manually by a lever 164 which opens a supply of pressure fluid from pipe 145 through pipe 166 containing a non-return valve 168 to piston 140. The exhaust brake 105 and fuel cut-off device 130 are controlled by a hand lever 163 which opens the pressure fluid supply to pipe 121<SP>1</SP> containing a spring-loaded overriding valve 170 which is held open by the pressure in pipe 166 when the coupling 134 is in operation. When the changeover lever 164 is moved to change down to the converter 133, the pressure supply to pipe 166 is cut off and valve 170 closes to render the exhaust brake inoperative and restore the idling fuel supply. The pressure in pipe 167 flows away slowly through a bleed orifice 173 so that the transmission changeover occurs after the exhaust brake 105 has opened. If the exhaust brake is not in operation when the lever 164 is moved to change down, a by-pass. 174, arranged to be closed by a valve 175 actuated by the pressure in the exhaust brake circuit 121<SP>1</SP> is opened and permits a rapid drop in pressure in pipe 167 so that the changeover is not delayed by the device 173. Specification 732,651 [Group XXIX] is referred to.