GB737353A - Improvements in the braking of motor vehicles with four-stroke reciprocating internal combustion engines - Google Patents

Abstract

737,353. Regulating; valve gear. SOC. ANON. A. SAURER. Sept. 1, 1953 [Sept. 24, 1952], No.24126/53. Class 7(6). In a four-stroke engine having means for cutting off the fuel and throttling the exhaust pipe to produce engine braking, the actuating means of the exhaust valve is adjusted to cause opening of the exhaust valve on the normal compression stroke as well as on the normal exhaust stroke simultaneously with the throttling of the exhaust pipe. In Fig. 1 an auxiliary valve lever 9 mounted on an eccentric pivot 8 and connected to the exhaust valve tappet 4 through a rod 14, is normally positioned out of contact with the cam 3 which acts directly on the tappet 4 to open the exhaust valve once each cycle for normal four stroke operation. For engine braking, a lever 10, connected to means for throttling the exhaust pipe and cutting off the fuel, is rotated to adjust the eccentric 8 to bring the lever 9 against the cam 3 whereby the exhaust valve is additionally opened through the lever 9 and rod 14 on the normal compression stroke, the braking action of the throttled exhaust gases thus occurring twice on each complete cycle. In a modification the lever 9 has a fixed fulcrum and is put into or out of operation by a movable link connected to the tappet 4. In Fig. 6 each exhaust valve has associated therewith two cams 65, 66 and tappets 62, 63 which operate the valve tappet 60 through a lever 72 pivoted on the tappet 62 and a movable roller 70. In the position shown the roller 70 is immediately above the tappet 62 whereby the tappet 63 is rendered ineffective and the engine operates normally. For engine braking the roller is moved to an intermediate position (shown dotted) whereby each tappet is operative and the exhaust valve is opened on each inward stroke of the piston, the exhaust pipe being simultaneously throttled. Alternatively for braking the roller 70 may be moved to a position above the tappet 63 which renders tappet 62 inoperative the cam 66 in this case having two cam rises 180 degrees apart to open the exhaust valve twice in each cycle. In Fig. 3 the exhaust valve is normally operated by a central cam 42 flanked by two cams 44, which latter are brought into operation for engine braking to open the valve on the normal compression stroke by the introduction of a forked member 56 between the cams and the tappet 48. In a further modification the cam shaft actuating the exhaust valves may be moved axially for engine braking to bring double lobed cams into action to cause the desired exhaust valve opening. The admission valves may also be caused to open twice each complete cycle during engine braking in addition to the exhaust valves by mechanism similar to that used for the exhaust valves, the time of opening on each outward stroke preferably being arranged when the air pressure in the cylinder is equal to that in the intake pipe.