Abstract: A variable-displacement piston-cylinder device may be adapted for providing work output, and/or for pumping or compressing fluids. The piston-cylinder device defines two or more coaxial cylindrical expansion chambers between a piston having two or more coaxial and conjoined piston members, and a correspondingly-shaped cylinder. Substantially any combination of the expansion chambers may be activated or deactivated in order to vary the effective displacement of the piston-cylinder device. The effective displacement of each piston-cylinder may be changed in mid-operation in order to reduce power output and fuel consumption (or pumping or compressing capacity), without introducing vibration. In addition, a control system is provided for managing the effective displacement of each piston-cylinder according to output required, desirable operating parameters, and other parameters that can effect the operation of the device.

Abstract: A variable-displacement piston-cylinder device may be adapted for providing work output, and/or for pumping or compressing fluids. The piston-cylinder device defines two or more coaxial cylindrical expansion chambers between a piston having two or more coaxial and conjoined piston members, and a correspondingly-shaped cylinder. Substantially any combination of the expansion chambers may be activated or deactivated in order to vary the effective displacement of the piston-cylinder device. The effective displacement of each piston-cylinder may be changed in mid-operation in order to reduce power output and fuel consumption (or pumping or compressing capacity), without introducing vibration. In addition, a control system is provided for managing the effective displacement of each piston-cylinder according to output required, desirable operating parameters, and other parameters that can effect the operation of the device.