Patent GB-753308-A (GB)
Title: Improvements in and relating to dual fuel engines
Inventor: SMITH JAMES MILLAR
IPC: F02D19/10
Filed: 1954-01-08
Abstract: 753,308. Regulating dual-fuel engines. ENGLISH ELECTRIC CO., Ltd. April 7, 1955 [Jan. 8, 1954], No. 1028/53. Class 7(6) In a dual-fuel engine wherein the air-control valves, metering the admission of combustion air to the engine in accordance with the different requirements for operation on oil fuel cnly, on gas fuel only or gas and oil fuel combined, are coupled to a cam follower Z, Fig. 1 (Provisional) which is both linked to the valves, not shown, metering the gas supply and follows a cam M operated by linkage controlled by the speed governor and by a hand lever R, the latter sets the cam M to positions corresponding to the operation of the engine on any of the above fuels and limits, if desired, the maximum amount of any of the fuels which can be adjusted by the governor. APPARATUS The lever R has a pawl co-operating with a segment T; the lever position determines the quantity of fuel with which the engine is to operate and the top and bottom parts of the segment, correspond to operation on gas and oil, respectively. The lever R is linked by a rod Q to a floating beam S, the latter also having the speed governor pivoted thereto at K and the slotted cam M articulated at J; the cam M which has two parallel but offset ranges that are interconnected by a third range, is formed with an extension guided between two knife edges N. The two extreme parts of the cam range need not be parallel and may be angled or curved. A lever P engages the cam M through the followed Z at one of its ends, the other end being linked to a rod F that is joined to a cam E, Fig. 2, (Provisional) with an arcuate form of slot therein, which cam is pivoted at G; the cam E is engaged by a pin at one end of a lever C, the apex of which is articulated to a rod B controlled by the gas metering valve or valves. The pin on which lever C and rod B are pivoted is arranged at the end of an arm H idly mounted on the axle A of the control linkage for the combustion air; an arm D is fixed to the axle A and engages a slot in the other end of the lever C. MODIFIED APPARATUS (a) OPERATION ON OIL FUEL In a modification, when the lever R, Fig. 1 (Complete) is in the position shown for operation of the engine on oil fuel, a slotted plate r has that part of its slot s, which is concentric with the pivot m of the lever R; engaged by a pin q<SP>11</SP> on the latter whereby motion of the lever is not transmitted to the plate r, and due to a rod Q joining a floating lever S to a lever fixed to the plate r, the lever S pivots about a point L under the influence of a governor arm a connected to the lever at a point K on a floating beam b. This motion of the lever S is transferred to the cam M articulated at J to the lever S but as the follower Z on a lever P is in a straight part of the cam the position of the air-metering valves is unaltered. A bell crank c mounted cn the pivot t of the plate r is prevented from turning anti-clockwise by dogs, not shown, engaging the plate r, therefore through a rod l the right end of the beam b is made a fixed fulcrum about which the beam rotates under the action of the governor arm a; consequently the movements of the latter are transmitted via a spring-loaded telescopic link j to a lever d connected to the fuel-pump racks, for example, not shown. As a fork d' abuts a pin q<SP>1</SP> on the lever R the arm a cannot adjust the fuel supply to exceed that set by the lever R whereupon the link j is compressed when the governor arm a tends to further move the fork d<SP>1</SP>. (b) OPERATION ON GAS FUEL When the lever R is moved to effect engine operation on gas fuel the pin q<SP>11</SP> engages the eccentric upper part of the slot s and rotates the plate r 'anti-clockwise about the pivot t whereupon the dogs disengage and the bell crank c is free to rotate anti-clockwise under the impulsion of the governor arm a, the point K serving as the fulcrum for the beam b and the oil supply being cut off due to the articulation of the beam b to the lever d through the link j. Motion of the bell crank c is transmitted via a rod h to a shaft x on which the lever P is mounted, and hence to the air-metering valves. Both the gas and air metering valves are thus controlled by the governor. The rotation of the plate r changes the position of the point' L and the lever S turns clockwise about the point K and pulls the cam M to the right so that the follower Z engages the left end of the cam slot and rotates the lever P thereby pulling down the rod F, Fig. 2, to adjust the air metering valves. Since the follower Z is again located in one of the parallel parts of the cam slot any further action of the governor arm has no effect on the air metering valves. When the engine is operating on gas fuel,  a  pilot injection of oil is preferably used, the amount of which is controlled by a nut p<SP>1</SP> on the link whereby the left side of the beam b is raised or lowered; by means of the slotted attachment at f of a part of the link j the quantity of pilot oil injected is determined by the engine load. (c) OPERATION OF A MIXTURE OF OIL AND GAS FUEL If as a result of failure of the gas supply or because a higher engine load is experienced than that for which the lever R is set, continued movement of governor arm a turns the beam b about the pivot L and rotates the fuel lever d through the link j to increase the air fuel supply; concomitantly the governor arm a turns the lever S to move the cam M so that the follower Z engages the oblique portion of the cam slot thereby adjusting the air-metering valves. The latter are thus controlled differently for engine operation on oil, gas and a mixture of both fuels. Specification 712,365 is referred to.