FREE-PISTON ENGINE HAVING A FLUID PRESSURE UNIT

摘要

A free-piston engine having a fluid pressure unit, comprises a cylinder (1) and a piston (2) arranged herein. The piston (2) has been equipped with a plunger-shaped extension (8) including a working section having a room bordered by a first axial face (15) of the plunger-shaped extension (8) and the volume of which is reduced when the piston (2) makes its expansion stroke, and to which discharge channel (19) means to a high pressure accumulator and supply channel means (25) from a supply reservoir (23) connects, and further comprises a compression section (33) including a chamber (34) having a first chamber portion (35) closed by a second axial face (42) in the bottom dead centre of the piston (2) and a second chamber portion (36) bordered by a third axial face (43). The first chamber (35) section decreasing at the start of the compression stroke of the piston, wherein the first chamber portion (35) has an open connection with a compression accumulator (37) through first connecting channel means (38) and the second chamber portion (36) is connected to the compression pressure accumulator (37) through a second connecting channel (39) and is connectable to pressure means (37, 50) for starting the compression stroke, whereafter the first connecting channel means (38) are opened in order to exert pressure on the third axial face (43). The plunger-shaped extension (8) comprises passage means extending from the first to the second chamber portion (36) in the bottom dead centre of the piston (2), whereas further a resiliently supported and axially movable closure element extends within the second chamber portion (36) that lies in the path of the passage means in the third axial face (43) and closes the passage means at the end of the expansion stroke of the piston (2) and opens it at the start of the compression stroke.