In an opposed-piston engine, a piston has a top land. The piston top land has a non-cylindrical shape which affords more clearance with a piston bore to thrust and anti-thrust sides than to front-facing and rear facing sides.

An electric device has a driveshaft with at least one stator cylinder positioned between opposing, curvilinear shaped cams mounted on the driveshaft, where the center axis of the stator cylinder is parallel with but spaced apart from the driveshaft axis. A magnet assembly is disposed in each end of the stator cylinder, with one magnet assembly engaging one cam and the other magnet assembly engaging the other cam. Each magnet assembly includes a cam follower that can move along a curvilinear shaped cam. A magnet slide arm attached to the cam reciprocates magnets carried on the magnet slide arm through electromagnetic windings disposed around the stator cylinder. An electrical input delivered to the windings can reciprocate the arm, driving the cams to rotate the driveshaft. Alternatively, rotation of the driveshaft can be used to reciprocate the arm to induce electric current in the windings.

Improvements to an engine comprise an air compressor cylinder with a piston, a combustion chamber cylinder with a piston. An engine has added an expansion chamber cylinder with a piston. Pistons each have a connecting rod and connecting rod head and associated parts adapted for reciprocating motion via combustion products, and a transmission associated with the engine. Improvements are to the piston seals, ignition assembly, valve shape and stem/rocker, valve operating mechanism, construction of head, heat management/heat shield, connecting rod/piston rotator, engine balancing, fuel pump placement, and a machining process.

A cylinder for an internal combustion opposed-piston engine includes a bore, either as part of the cylinder directly or of a liner. The bore has a surface for guiding a pair of pistons disposed for opposing movement in the cylinder. The cylinder bore has three zones of surface finishes: an inner zone extending between and including exhaust and intake ports, where only piston compression rings travel on the bore surface; two instances of an outer zone where only piston oil control rings travel on the bore surface; and two instances of a port zone where both types of rings travel on overlapping paths in the same bore surface portion. Each zone may have a particular surface finish that is tailored to specific requirements including oil control, ring wear, and scuff resistance relevant to the zone.

A hybrid drive system has two sources of driving power: a non-combustion drive system to provide mechanical torque and rotation to a driveshaft, and an opposed-piston, internal combustion engine configured to provide energy for the non-combustion drive system.

An internal combustion engine system includes a reciprocating compressor for pressurizing a fluid medium and having a compressor cylinder for accommodating a compressor piston. The compressor cylinder has a main cylinder volume and a secondary adjustable volume in fluid communication with the main cylinder volume so as to provide a variable geometrical compression ratio.

Compact and quiet opposed piston engines (OPEs) are provided. Though compact and quiet, the OPEs provide substantial mechanical shaft power that is required for a range of applications. The inventive OPEs may have a plurality of size displacements.

A connecting rod assembly has a connecting rod with a large end and a small end, a piston wrist pin, and fasteners to connect the connecting rod to the piston wrist pin and optionally one or more shims in between the connecting rod and piston wrist pin. A notch on the wrist pin allows for the seating of a flat surface on the small end of the connecting rod in the connecting rod assembly. Side walls on both the notch and the small end of the connecting rod limit twist. The connecting rod assembly allows for the adjustment of piston location in a cylinder while limiting connecting rod twist.

A hybrid drive system has two sources of driving power: a non-combustion drive system to provide mechanical torque and rotation to a driveshaft, and an opposed-piston, internal combustion engine configured to provide energy for the non-combustion drive system.

An engine placement configuration for a heavy-duty truck includes a chassis having two spaced-apart frame rails running in a longitudinal direction of the chassis, between front and rear ends, and a front wheel assembly with an axle attached to the frame rails. An opposed-piston engine is supported on the frame rails and positioned between the front end and the axle. The opposed-piston engine includes a cylinder assembly with a longitudinal axis disposed between the frame rails and oriented vertically with respect to the longitudinal direction. Alternatively, the opposed-piston engine includes a row of cylinders disposed between the rails and running in the longitudinal direction.