A cooler machine using the Stirling cycle and comprising: at least one compressor with a compressor piston movable in a compression cyclinder; a regenerator with a regenerator piston movable in a regeneration cyclinder placed at a given angle relative to the compression cyclinder; a rotary drive crank; and two connecting rods, respectively a compressor connecting rod coupled to the compressor piston, and a regenerator connecting rod coupled to the regenerator piston, and both coupled to the crank with a mutual angular offset; the compressor and/or regenerator connecting rod is arranged to be of length that is variable over a rotation of the crank in such a manner that the movement of the corresponding piston is least slowed down on passing through top and/or bottom dead center.