A mechanical liquid piston slow expansion compressor defining a variable pneumatic volume which forms a compressor or an expander, a working gas being able to enter said volume via an input port or exit from said volume via an outlet port, comprising:
- A liquid cylinder which can, directly or indirectly, pivot about a tilt axis which is perpendicular to the axis of said cylinder and which is secured to a static frame;
- A hydraulic piston which can sealingly translate into the liquid cylinder to form with the latter, a variable hydraulic volume which is totally or partially filled with a working liquid;
- A gas and liquid reservoir which is connected to the variable hydraulic volume by a communication conduit, such that said reservoir is mainly or totally filled with working liquid when the variable hydraulic volume is minimum, and is totally or partially filled with working gas when the variable hydraulic volume is maximum, the variation of absolute volume of the working gas contained in the variable pneumatic volume forming on the one hand, the variable pneumatic volume, and being on the other hand, approximately equal to the variation of absolute volume of the working liquid contained in the variable hydraulic volume;
- Heat exchange and accumulation means housed in the gas and liquid reservoir, said means being able, on the one hand, to exchange heat with the working gas or with the working liquid and on the other hand, to temporarily store all or some of said heat;
- Heat export or input means which take or which transfer, directly or indirectly, heat to the heat exchange and accumulation means and/or to the working liquid and/or to the working gas, said heat taken then being transferred to heating means or said transferred heat having been taken beforehand to cooling means, said heating means and said cooling means being external to the gas and liquid reservoir;
- Filling means which enable or prohibit the passage of working gas from an intake plenum to the gas and liquid reservoir via the inlet port;
- Draining means which enable or prohibit the passage of working gas from the gas and liquid reservoir to a repression plenum via the outlet port;
- A connecting rod a first rod end of which is fixedly secured to the hydraulic piston, said rod being approximately parallel to the longitudinal axis of said piston;
- Piston guiding means which maintain the hydraulic piston and the connecting rod parallel to said cylinder, whatever the position of said piston in said cylinder;
- A crankshaft which can rotate about an axis parallel to the tilt axis in at least one shaft bearing, and which has at least one crank around which a second rod end of the connecting rod is articulated;
- At least one drive motor which directly or indirectly rotates the crankshaft;
- Kinetic energy storage means, which are directly or indirectly connected to the crankshaft.