Piston arrangement and internal combustion engine

Abstract

As disclosed herein, a piston arrangement may include a cylinder, a piston head movable along a piston axis within the cylinder, a con rod, and a track. The con rod has a first end which is coupled to the piston head and a second end which is coupled to the track. The track is adapted to be moved relative to the cylinder and is shaped such that, as the track moves relative to the cylinder, the piston head moves in reciprocating motion along the piston axis in accordance with a path of the track. The path of the track may be shaped such that piston head displacement is non simple harmonic with respect to displacement of the track relative to the cylinder.

1 . An internal combustion engine having a piston arrangement, the piston arrangement comprising:
 a cylinder;   a piston head movable along a piston axis within the cylinder;   a con rod;   a swinging arm pivotally attached to a fixed point on the engine and to the con rod; and   a track having a path;   wherein the con rod has a first end which is coupled to the piston head and a second end which is coupled to the track;   wherein the track is adapted to be moved relative to the cylinder and is shaped such that, as the track moves relative to the cylinder, the piston head moves in reciprocating motion along the piston axis in accordance with the path of the track; and   wherein the path of the track is shaped such that piston head displacement is non simple harmonic with respect to displacement of the track relative to the cylinder.   
     
     
         2 . An internal combustion engine according to  claim 1 , wherein the track has a path shape which is not sinusoidal. 
     
     
         3 . An internal combustion engine according to  claim 1 , wherein the track has a first local minimum and a second local minimum different to the first local minimum such that as the piston head moves in reciprocating motion along the piston axis it passes through a first bottom dead center position corresponding to the first local minimum of the track and subsequently passes through a second bottom dead center position corresponding to the second local minimum of the track, wherein the piston head is at a different displacement with respect to the cylinder when it is in the second bottom dead center position to when it is in the first bottom dead center position. 
     
     
         4 . An internal combustion engine according to  claim 1 , wherein the track includes at least one portion of reduced gradient at a location between a local minimum of the track and an adjacent local maximum of the track such that as the piston head moves between a bottom dead center position corresponding to the local minimum and a TDC position corresponding to the local maximum it experiences at least one period of reduced speed. 
     
     
         5 . An internal combustion engine according to  claim 1 , wherein the track includes a prolonged portion of low gradient or zero gradient at or near a local maximum or local minimum of the track such that, as the piston head moves through a top dead center position corresponding to the local maximum or through a bottom dead center position corresponding to the local minimum, it experiences a substantial period of dwell time. 
     
     
         6 . An internal combustion engine according to  claim 1 , wherein the track forms a closed loop and is provided on a rotating body. 
     
     
         7 . An internal combustion engine according to  claim 1 , wherein the track is provided on a drum or disk which rotates relative to the cylinder. 
     
     
         8 . An internal combustion engine according to  claim 7 , wherein the track is provided on an inner or outer radial surface of a drum, or on an end surface of a drum, or on an outer radial surface of a disk or on an end surface of a disk. 
     
     
         9 . An internal combustion engine according to  claim 8 , wherein the track is recessed into and/or protrudes from a surface of the drum or disk. 
     
     
         10 . An internal combustion engine according to  claim 1 , wherein the con rod has one or more followers which engage the track to control displacement of the con rod. 
     
     
         11 . An internal combustion engine according to  claim 10 , wherein the con rod has at least two followers which are spaced apart from each other in a direction parallel to the cylinder axis. 
     
     
         12 . An internal combustion engine according to  claim 10 , wherein the con rod has at least two followers mounted to the con rod via a bogie which is pivotally mounted to the con rod. 
     
     
         13 . An internal combustion engine according to  claim 10 , wherein the track includes a first surface which engages one or more of the followers to move the piston head in a first direction along the piston axis and a second surface opposing the first surface which engages one or more of the followers to move the piston head in a second direction opposite to the first direction along the cylinder axis. 
     
     
         14 . An internal combustion engine according to  claim 1 , wherein the con rod is constrained to move substantially in the direction of the cylinder axis without rotating relative to the piston head. 
     
     
         15 . An internal combustion engine according to  claim 1 , including at least two piston arrangements which are each said piston arrangement recited in  claim 1 , wherein the respective con rods of the at least two piston arrangements are coupled to a common track. 
     
     
         16 . An internal combustion engine according to  claim 1 , comprising first and second piston arrangements which are each said piston arrangement recited in  claim 1 , wherein con rods of the first and second piston arrangements are respectively coupled to separate first and second tracks, wherein the first and second tracks are moveable with respect to each other to vary the relative timing of the respective piston heads of the first and second piston arrangements. 
     
     
         17 . An internal combustion engine comprising first and second piston arrangements which are each said piston arrangement recited in  claim 1 , wherein the first and second piston arrangements respectively comprise first and second piston heads movable within a common cylinder, wherein the first and second piston heads oppose each other such that a chamber is formed between the first and second piston heads. 
     
     
         18 . An internal combustion engine according to  claim 1 , wherein the con rod is coupled to the track via a bogie. 
     
     
         19 . An internal combustion engine according to  claim 18 , wherein the swinging arm is attached to the con rod at the bogie. 
     
     
         20 . An internal combustion engine according to  claim 18 , wherein the bogie has a wheel mounted on the bogie for engaging the track. 
     
     
         21 . An internal combustion engine according to  claim 20 , wherein the wheel is received in the track. 
     
     
         22 . An internal combustion engine according to  claim 18 , wherein the swinging arm reacts a side load exerted on the bogie by the track. 
     
     
         23 . An internal combustion engine according to  claim 1 , wherein the swinging arm has an oil delivery passage.