This invention relates to the field of internal combustion engines and compressors in general and to linear compressors, in particular these used as in U.S. Pat. No. 8,056,527, by accurately controlling the pressure being delivered into the combustion chambers of said engine while returning unused energy of the compression phase into the motor for complete expansion.

Another improvement relates to a pressure compensated vane to be used inside grooves of the motor assembly rotor. This invention enables the vane to seal against the cavity of the housing tightly with minimal force.

This invention relates to the field of internal combustion engines and compressors in general and to linear compressors, in particular these used as in U.S. Pat. No. 8,056,527, by accurately controlling the pressure being delivered into the combustion chambers of said engine while returning unused energy of the compression phase into the motor for complete expansion.

Another improvement relates to a pressure compensated vane to be used inside grooves of the motor assembly rotor. This invention enables the vane to seal against the cavity of the housing tightly with minimal force.

Provided is an improved bypass durable dart plunger that descends faster in a hydrocarbon well, is capable of lifting more fluids and has a durable and replaceable clutch assembly. The various components of the durable dart plunger includes a sleeve, a dart body with a one or more flow ports (chokes) cut at right angles through the dart body, a pin and a replaceable clutch assembly (also referred to a retention assembly). The chokes can be of varying sizes. In one embodiment, the clutch assembly includes a plurality of clutch mechanisms wherein each mechanism includes a ball, a socket screw and a resilient spacer.

Provided is an improved bypass durable dart plunger that descends faster in a hydrocarbon well, is capable of lifting more fluids and has a durable and replaceable clutch assembly. The various components of the durable dart plunger includes a sleeve, a dart body with a one or more flow ports (chokes) cut at right angles through the dart body, a pin and a replaceable clutch assembly (also referred to a retention assembly). The chokes can be of varying sizes. In one embodiment, the clutch assembly includes a plurality of clutch mechanisms wherein each mechanism includes a ball, a socket screw and a resilient spacer.

An improved free piston assembly for use in combination with a plunger lift assembly is provided. The piston assembly includes a sleeve member, a retention sleeve, and a flow restriction member. The sleeve member has an inner surface defining an opening for the flow of formation fluids. The opening includes a first section and a second section. The retention sleeve is configured to be affixed to the first section of the opening. The flow restriction member is not latched to the sleeve member and is configured to have an interference fit with the retention sleeve. The interference fit provides a force that is sufficient to overcome the force of gravity on the flow restriction member when formation fluid forces acting on the flow restriction member are decreased or removed. The second section of the opening is configured to prevent the passage of the flow restriction member.

An improved free piston assembly for use in combination with a plunger lift assembly is provided. The piston assembly includes a sleeve member, a retention sleeve, and a flow restriction member. The sleeve member has an inner surface defining an opening for the flow of formation fluids. The opening includes a first section and a second section. The retention sleeve is configured to be affixed to the first section of the opening. The flow restriction member is not latched to the sleeve member and is configured to have an interference fit with the retention sleeve. The interference fit provides a force that is sufficient to overcome the force of gravity on the flow restriction member when formation fluid forces acting on the flow restriction member are decreased or removed. The second section of the opening is configured to prevent the passage of the flow restriction member.

A free piston device, comprises a housing with a cylindrical inner wall having a first wall opening and a second wall opening; a cylindrical piston movable in axial direction and rotatable around its longitudinal axis; the piston comprising a first skirt forming a first chamber, said first skirt having at least a first opening in the form of a hole through the wall of the skirt for allowing passage of a fluid directly into or out of said chamber; control means for controlling axial and angular movement of said piston; sensing means for providing signals related to the axial position and/or the angular position of the piston; a digital control unit for rotating the piston around its longitudinal axis in synchronism with its axial movement.

A free piston device, comprises a housing with a cylindrical inner wall having a first wall opening and a second wall opening; a cylindrical piston movable in axial direction and rotatable around its longitudinal axis; the piston comprising a first skirt forming a first chamber, said first skirt having at least a first opening in the form of a hole through the wall of the skirt for allowing passage of a fluid directly into or out of said chamber; control means for controlling axial and angular movement of said piston; sensing means for providing signals related to the axial position and/or the angular position of the piston; a digital control unit for rotating the piston around its longitudinal axis in synchronism with its axial movement.

Provided is an improved bypass durable dart plunger that descends faster in a hydrocarbon well, is capable of lifting more fluids and has a durable and replaceable clutch assembly. The various components of the durable dart plunger includes a sleeve, a dart body with a one or more flow ports (chokes) cut at right angles through the dart body, a pin and a replaceable clutch assembly (also referred to a retention assembly). The chokes can be of varying sizes. In one embodiment, the clutch assembly includes a plurality of clutch mechanisms wherein each mechanism includes a ball, a socket screw and a resilient spacer.

Provided is an improved bypass durable dart plunger that descends faster in a hydrocarbon well, is capable of lifting more fluids and has a durable and replaceable clutch assembly. The various components of the durable dart plunger includes a sleeve, a dart body with a one or more flow ports (chokes) cut at right angles through the dart body, a pin and a replaceable clutch assembly (also referred to a retention assembly). The chokes can be of varying sizes. In one embodiment, the clutch assembly includes a plurality of clutch mechanisms wherein each mechanism includes a ball, a socket screw and a resilient spacer.