Patent GB-1364068-A (GB)
Title: Starting a free piston engine
IPC: F02N99/00
Filed: 1971-08-18
Abstract: 1364068 Free piston engines; starting ignition devices A BRAUN 18 Aug 1971 [24 Aug 1970] 38810/71 Headings F1B and F1K A free piston engine includes ignition means for igniting fuel in a cylinder for combustion on a compression stroke of the piston during normal running of the engine, means for supplying at starting a combustible starting mixture to the (or another) cylinder, means for driving the piston in a preliminary compression stroke prior to ignition for a first working stroke and auxiliary means for igniting the combustible starting mixture for initiating the first working stroke as the piston reaches a position on the preliminary compression stroke at which pressure in the cylinder is substantially below the pressure at which ignition occurs during normal running of the engine. During operation, the output from compressor chamber 34 is fed through the one-way valve 32 into a compressor discharge manifold 52. The discharge manifold has an outlet conduit 53 which communicates with a further conduit 54 connected to a suitable air storage tank or reservoir 56. Communication between conduits 53 and 54 is controlled by a discharge valve 57. When the engine starts operation and sufficient pressure is generated within the conduit 53 the output from the compressor will be fed to the storage reservoir. In order to relieve the pressure within the compressor chamber 34 whenever the engine shuts down and thus facilitate the arrangements for starting the engine, a manifold pressure discharge conduit 59 is connected at one end to the discharge manifold 52. The other end of the conduit 59 is controlled by a valve 61. Upward movement of the movable portion of the valve against the urging of the spring 62 effectively connects the conduit 59 with a conduit 63 by the passage 64. The valve 61 is operated in any suitable manner at the time the engine is shut down in order to ensure closing of the outlet valve 57 and thus prevent escape of pressure from the reservoir 56 back through the manifold 52. When the engine 17 is shut down and it is desired to position the pistons 20 and 26 for a starting cycle the valve 68 is operated towards the right air is introduced under pressure into the bouncer chamber 42 and the compressor chamber is connected to the atmosphere so that the piston assembly is moved to the right. For a starting cycle the power cylinder 21 is charged with a combustible mixture which may be introduced through its inlet port 14. A starting valve 94 is provided. When the valve is operated to the left it connects an auxiliary air supply 98 to the carburetter 91 and an appropriate starting mixture is introduced into the power cylinder 21. To start the engine the valve 68 is operated to  the left so that the valve section 81 will connect the low-pressure air from the conduit 73 through the conduit 82 to the compressor chamber 34 and vent the bounce chamber 42 to atmosphere at 78. Thus the higher pressure in the chamber 34 moves the piston assembly to the left to start the engine. The starting arrangement may utilize a manual air pump for air at 73 and 98. The starting switch 136 is actuated when it is desired to have the breaker points 112 in circuit. The ignition adjustment member 116 may be gradually moved to the left so that successive power strokes are started by combustion at points gradually closer to the normal desired inner reversal point 138. Switch 136 may be opened so that the ignition point is controlled by breaker points 137. Modified ignition arrangements are described.