A fluid machine for a pneumatic or hydraulic drive system, said fluid machine being able to work as a fluid motor or as a fluid pump, comprising: at least two piston assemblies each comprising a piston means (110a-c), the at least two piston assemblies being operable to cause sequential reciprocating movement of the pistons means (110a-c); a drive member (120) rotatable about an axis and providing an annular, wave-like surface (122) extending at least partially radially to the axis, towards which the piston means (110a-c) project, wherein, in case of working as a fluid motor, the pistons means (110a-c) are arranged to drive rotation of the drive member (120) about the axis at least by a pushing action on said wave-like surface (122) or, in the case of working as a fluid pump, the piston means (110a-c) are arranged to cooperate with said wave-like surface (122) so that rotation of the drive member (120) drives sequential reciprocating motion of the piston means (110a-c).

An opposed piston engine has a driveshaft with at least one combustion cylinder positioned between opposing, curvilinear shaped cams mounted on the driveshaft, where the center axis of the combustion cylinder is parallel with but spaced apart from the driveshaft axis. A piston assembly is disposed in each end of the cylinder, with one piston assembly engaging one cam and the other piston assembly engaging the other cam. Each piston assembly includes a cam follower that can move along a curvilinear shaped cam to reciprocate the piston assembly within the cylinder. The combustion cylinder includes an intake port in fluid communication with an annular intake channel formed in the engine block in which the cylinder is mounted, and an exhaust port in fluid communication with an annular exhaust channel formed in the engine block.

Stepper motor with a housing 1,2,4,6,16, in which a cylindrical rotor 11,15 fixed on a central shaft 12 can rotate but not translate along an axial direction. There are cylindrical translators 9, 14 on both sides of the rotors 11, 15, where the translators 9, 14 are sealed fit in a cylindrical space within the housing 6 and around the central shaft 12 and where the translators 9, 14 can only translate in an axial direction, where in one axial position of a translator 9, 14 a set of triangular asymmetric teeth 20 located on the translator 9, 14 can interact and fit into a set of triangular asymmetric teeth 21 on the rotor 11, 15, where the shape of the teeth 21 on both sides of the rotor 11, 15 is symmetric and where one of the sets of teeth 20, 21 between one translator 9 (14) and the rotor 11 (15) and a set of teeth 20, 21 between the other translator 9 (14) and the rotor 11 (15) are tangentially shifted, i.e. offset over a length equal to half the width of a tooth 20, 21 and where the translators 9, 14 can be moved by a pressure difference between the part of the cylindrical space between the housing 6 and a translator 9, 14 and the part of the cylindrical space between the translator 9, 14 and the rotor 11, 15.

An opposed piston engine has a driveshaft with at least one combustion cylinder positioned between opposing, curvilinear shaped cams mounted on the driveshaft, where the center axis of the combustion cylinder is parallel with but spaced apart from the driveshaft axis. A piston assembly is disposed in each end of the cylinder, with one piston assembly engaging one cam and the other piston assembly engaging the other cam. Each piston assembly includes a cam follower that can move along a curvilinear shaped cam to reciprocate the piston assembly within the cylinder. The combustion cylinder includes an intake port in fluid communication with an annular intake channel formed in the engine block in which the cylinder is mounted, and an exhaust port in fluid communication with an annular exhaust channel formed in the engine block.

A hybrid engine having a plurality of combustion power assemblies disposed about an engine driveshaft on which is mounted spaced apart cams, each combustion power assembly disposed between the cams radially outward of the driveshaft and having a combustion cylinder with a fuel injector mounted thereon and with a reciprocating piston assembly disposed in each end of the combustion cylinder. A cam follower is attached to each piston assembly and engages a respective cam. An electric power assembly may be mounted radially outward from the driveshaft and adjacent at least one cam as a radial power assembly or may be mounted along the driveshaft between the two cams as an axial power assembly.

Stepper motor with a housing 1,2,4,6,16, in which a cylindrical rotor 11,15 fixed on a central shaft 12 can rotate but not translate along an axial direction. There are cylindrical translators 9, 14 on both sides of the rotors 11, 15, where the translators 9, 14 are sealed fit in a cylindrical space within the housing 6 and around the central shaft 12 and where the translators 9, 14 can only translate in an axial direction, where in one axial position of a translator 9, 14 a set of triangular asymmetric teeth 20 located on the translator 9, 14 can interact and fit into a set of triangular asymmetric teeth 21 on the rotor 11, 15, where the shape of the teeth 21 on both sides of the rotor 11, 15 is symmetric and where one of the sets of teeth 20, 21 between one translator 9 (14) and the rotor 11 (15) and a set of teeth 20, 21 between the other translator 9 (14) and the rotor 11 (15) are tangentially shifted, i.e. offset over a length equal to half the width of a tooth 20, 21 and where the translators 9, 14 can be moved by a pressure difference between the part of the cylindrical space between the housing 6 and a translator 9, 14 and the part of the cylindrical space between the translator 9, 14 and the rotor 11, 15.

A hybrid engine having a plurality of combustion power assemblies disposed about an engine driveshaft on which is mounted spaced apart cams, each combustion power assembly disposed between the cams radially outward of the driveshaft and having a combustion cylinder with a fuel injector mounted thereon and with a reciprocating piston assembly disposed in each end of the combustion cylinder. A cam follower is attached to each piston assembly and engages a respective cam. An electric power assembly may be mounted radially outward from the driveshaft and adjacent at least one cam as a radial power assembly or may be mounted along the driveshaft between the two cams as an axial power assembly.

An opposed piston engine has a driveshaft with at least one combustion cylinder positioned between opposing, curvilinear shaped cams mounted on the driveshaft, where the center axis of the combustion cylinder is parallel with but spaced apart from the driveshaft axis. A piston assembly is disposed in each end of the cylinder, with one piston assembly engaging one cam and the other piston assembly engaging the other cam. Each piston assembly includes a cam follower that can move along a curvilinear shaped cam to reciprocate the piston assembly within the cylinder. The combustion cylinder includes an intake port in fluid communication with an annular intake channel formed in the engine block in which the cylinder is mounted, and an exhaust port in fluid communication with an annular exhaust channel formed in the engine block.

An opposed piston engine has a driveshaft with at least one combustion cylinder positioned between opposing, curvilinear shaped cams mounted on the driveshaft, where the center axis of the combustion cylinder is parallel with but spaced apart from the driveshaft axis. A piston assembly is disposed in each end of the cylinder, with one piston assembly engaging one cam and the other piston assembly engaging the other cam. Each piston assembly includes a cam follower that can move along a curvilinear shaped cam to reciprocate the piston assembly within the cylinder. The combustion cylinder includes an intake port in fluid communication with an annular intake channel formed in the engine block in which the cylinder is mounted, and an exhaust port in fluid communication with an annular exhaust channel formed in the engine block.

An opposed piston engine has a driveshaft with a first combustion cylinder parallel with a driveshaft and disposed about the driveshaft at a first radius and a second combustion cylinder parallel with the driveshaft and disposed about the driveshaft at a second radius greater than the first radius. A first pair of curvilinear shaped cams are associated with the first combustion cylinder and disposed on the driveshaft and a second pair of curvilinear shaped cams are associated with the second combustion cylinder and disposed on the driveshaft outwardly of the first pair of cams.