Patent GB-190813260-A (GB)
Title: Improvement in and relating to Gas Engines.
Inventor: BROUGHAM FREDERICK JOHN
Filed: 1908-06-22
Granted: 1908-12-31
Abstract: 13,260. Brougham, F. J., [Southwark Foundry and Machine Co.]. June 22. Gas engines.-Cut-off valves controlling the gas and air supplies to the mixing-chambers are connected to the admission - valve gear by yielding connexions which are ncrmally prevented from moving with the valve-gear but are released to cut off the admission at a point determined by the governor, by the closing of electric circuits controlled by an adjustable rotary switch. The switch may comprise in addition a set of contacts also controlled by the governor for timing the ignition, and the arrangement may be such that the ignition is only appreciably adjusted when the speed of the engine falls considerably. The invention is described in connexion with a two-cylinder tandem double-acting engine, in which the admission and exhaust valves are actuated by two sets of reciprocating cams as described in Specification No. 19,539, A.D. 1906. The cut-off valve comprises a piston M, Fig. 4, and cylindrical sleeve M' having air and gas ports M<2>, M<3> which normally coincide with ports in the valve casing. The piston M works in a vacuum chamber, and is only free to descend when an electro-magnet 0<1> is energized and lifts a valve N to open a port D" to the atmosphere. A piston L<6> is mounted on the admission valve stem and carries a cylindrical sleeve having ports L<4>, L<5>. When the admission valve is opened by the valve-gear, the piston L<6> is moved downwards bringing the ports L<4>, L<5> into register with the ports M<2>, M<3>, and a vacuum is formed between the pistons L<6>, M, but air is admitted freely to the space M<7> so that gas is not drawn into the vacuum chamber from the admission ports. When the electro-magnet 0<1> is energized and lifts the valve N, the piston M descends and the gas and air supplies are cut off. The circuits of the electro-magnets for the four cut-off valves are controlled by a rotary switch, Figs. 5 and 6. The rotating contact is a roller P<9> mounted on a lever carried by a collar P<5> which is keyed to an insulated bushing on.a shaft P'. The roller is pressed outwards by the action of a spring P<8>, and makes contact in succession with the inner ends of insulated posts R<1>, R<2>, R<3>, R<4>, each connected to an insulated strip such as T<3>. The contacts R<1> &c. are mounted on drum R which is adjusted angularly by the governor. Fixed contacts T<6>, pressed inwards by springs T<8>, bear upon the circumferential parts of the strips T<3>, and each is connected to one end of the winding of the corresponding electro-magnet. The rotating contact P<9> is connected to one terminal of a battery through the collar P<5>, V-shaped ring P<11>, rod P<12>, and spring P<14> ; the other battery terminal and the other ends of the windings of the electro magnets are connected to earth through the engine. A similar rotating contact P<10> and adjustable contacts, such as S<4>, control the ignition circuits, timing being effected by the angular adjustment of the drum S. The drums R, S are connected by arm R<10>, S<10> and adjustable links W<1>, W<2>, Fig. 2, to arms W<3>, W<4> on a rock-shaft W controlled by the governor, the arm W' normally making an obtuse angle with the link W<2> so that the time of ignition is not appreciably altered until the speed has fallen considerably. The igniting-spark passes between an insulated terminal Z' and a bushing Z<5>, and more than one sparking-plug may be provided in each combustion chamber.