Patent GB-1132975-A (GB)
Title: Improvements in regulation devices for free piston internal combustion engines
IPC: F01B11/08
Filed: 1965-11-23
Abstract: 1,132,975. Hydraulic transmissions. SOC. ANON. ANDRE CITROEN. 23 Nov., 1965 [25 Nov., 1964], No. 49655/65. Heading F2D. [Also in Division F1] A free-piston I.C. engine has its piston 7 rigid with a pump plunger 2 forming part of an hydraulic transmission with a motor B. Each side of piston 7 is rigidly connected to tubular pistons 2 which reciprocate in cylinder 1. Two damping chambers C and D and a holding chamber E communicate with each cylinder 1. The hydraulic generator delivers pressurized fluid via delivery valves 4 and pipes 5 to motor B which returns fluid via pipes 6 and suction valve 3 to the hydraulic generator. On each piston stroke part of the fluid delivered by piston 2 is admitted into a chamber 41 which causes membrane 43 to expand to compress pressurized gas present in chamber 42 and also acts via passage 48, to move piston 49 thereby closing check valve 45. Delivery valve 4 then opens to permit delivery of the remaining part of the fluid. During the next suction stroke, the energy corresponding to the compression of gas in chamber 42 is restored to the plunger 2 and check valve 45 reopens. The power supplied to the motor B depends on the relative amounts of the two parts of the fluid delivery and therefore on the pressure of gas supplied from source M. The gas pressure is controlled by a pedal 50 which may control a distributing valve connecting a pressurized gas reservoir either with the delivery of a compressor or to atmosphere. In a modification pistons 53, Fig. 2, may be connected through a mechanism (not described) to control the pressure of the gas source M. Fuel regulation.-When pressure reduces in chamber 34 fuel from pipe 18 opens check valve 19 and pushes metering member 15 leftwards until washer 28a engages abutment 62a thus admitting fuel into space 17 proportionally to displacement l. At the end of movement of piston 7 to the right, pressure in chamber 34 is transmitted via passage 31 to head 15b. When the edge of sleeve 26 clears orifice 21 metering member 15 is driven to the right until orifice 21 is closed. A portion of the fuel volume is injected and is then driven by the air stream flowing through passages 31, 32 into chamber 33 where it is ignited. When orifice 22 is cleared the remaining fuel portion is injected and combustion in chamber 33 reverses the flow through passages 32 and 31 to cause an ignited fuel mixture to be injected into chamber 34. If the stroke of piston 2 exceeds a predetermined value the end of piston 2 enters hole 51 and fluid therein is directed via passage 56 and chamber 54 to act on piston 53. As piston 53 is moved leftwards the motion is transmitted via lever 66b, link 65b, lever 63b to move abutment 62b to the left, thus making the subsequent sliding displacement of the left hand metering member 15 smaller. This results in the next fuel injection on the left of piston 7 being smaller thereby reducing the length of the next rightwards movement of the piston. A similar adjustment occurs for the leftwards movement of the piston. If overpressure does not exist in hole 51, i.e. if the stroke is short, a check valve 59 is closed and fluid pressure is communicated via a small passage 60 to chamber 55. The differential pressures acting on piston 53 cause it to move to reduce the volume of chamber 54. This movement increases the length l at the opposite end of the engine thereby increasing the rate of fuel injection to increase the length of the subsequent stroke. In a modification piston 53, Fig. 3 (not shown), is biased by an external spring 61.