Abstract: A procedure for startup and shutdown of an internal combustion engine with an electronically-controlled turbocharger (ECT) is disclosed. The startup and shutdown procedures are determined to provide the desired lubrication to engine and ECT components and sufficient cooling of the engine and ECT. In one embodiment, the system includes an electric oil pump that can supply oil to the oil circuit in the engine and ECT independently of an engine-driven mechanical oil pump. In another embodiment, the oil circuit is provided with an oil accumulator to provide oil for cooling after engine rotation has stopped.

Abstract: It is important to maintain the temperature in the ring pack area of the piston of an internal combustion engine below about 270° C. to maintain proper ring function and lubrication. Disclosed is a piston with a heat barrier groove between the piston top and the ring pack and a method to construct such a piston. The heat barrier groove extends inwardly toward the center of the piston a greater distance than the compression ring grooves. In one embodiment, a low thermal conductivity material is placed in the inner portion of the heat barrier groove and a split ring is place in the outer portion. In another embodiment, a gas is provided in the inner portion and the split ring is welded to the piston so that the inner portion of the heat barrier groove is sealed, i.e., welding at the upper and lower edges and at the gap.

Abstract: An opposed-piston engine has a plurality of intake ports wrapped around the cylinder wall. It is desirable to obtain high swirl ratio flow with minimal pressure drop. A system have a generally-volute shaped plenum is disclosed. A centerline of the volute spirals inwardly. Furthermore, the cross-sectional area of the volute decreases in the direction of flow. The area is decreased as the flow from the plenum enters intake ports so that the velocity of flow in the plenum near the downstream end does not slow precipitously. The intake system may have multiple such volute-shaped plena coupled to mutually exclusive subsets of the intake ports. The volute shape leads to a high swirl ratio with limited drop in flow energy.

Abstract: In a piston-ported engine, a sealing ring may be placed in a groove in the cylinder. As the groove is of greater diameter than the cylinder, the sealing ring overlaps into a helix allowing it to be enter the cylinder. However, such a helix does not fit into a groove without when in the helix. Alternatively, a shorter sealing ring is placed into the groove. However, the gap is too large. According to one embodiment, a groove of double the width of the ring is provided and the helical ring is installed and caused to unwind in the groove so that the ring sits in a plane. A spacer ring is placed in the groove to fill the extra space in the groove. An elastomeric material or a tension spring in an outer groove in the sealing ring can be used to cause the ring to press against the piston.

Abstract: In two-stroke engines, it is common to provide two compression rings on the piston and an additional oil ring. The oil ring can be on the piston, but yields a longer piston. Alternatively, the oil ring is placed in a circumferential groove in the cylinder liner. One problem with such a configuration is that the compression rings move with respect to the oil ring and the annular volume between the two is compressed during reciprocation of the piston, which can cause pumping of oil into the ports. According to embodiments of the present disclosure, axial slots are formed in the cylinder liner that extends from the circumferential groove toward the ports extending along the bridges and beyond the ports. This provides a vent for the annular volume to avoid pumping the oil into the ports.

Abstract: In some two-stroke engines, a stationary ring is disposed in a groove in the cylinder liner. However, it is a challenge to install such a stationary ring while maintaining a narrow gap to minimize gas flow through the gap. A ring system for an internal combustion engine is disclosed that includes an L-shaped, split ring with a reentrant angle and a nested, split ring with a convex quadrilateral cross section nested with the L-shaped ring proximate the reentrant angle. The two rings are affixed so that the two gaps of the split rings cannot align. Or, in other embodiments, the two are allowed to rotate relative to each other over a predetermined angle.

Abstract: Reciprocating motion can be converted to rotary motion through a crankshaft and a connecting rod. In a connecting rod that is primarily in tension, two opposing connecting rods can be coupled to a single journal. Two bearing caps are placed over the journal, the bearing caps having fingers that extend away from the bearing cap with the fingers of the two bearing caps being enmeshed. Fingers of each bearing cap are coupled to the connecting rods. The resulting joint is compact and lighter weight with a shorter journal than prior joints.

Abstract: A combustion chamber of an internal combustion engine has primary intake ports located a first distance from the crankshaft and primary intake ports located a second distance from the crankshaft. One or more unidirectional valves, such as reed valves, are place in an intake duct upstream of the primary intake ports. The valves prevent backflow from the cylinder into the intake when the pressure in the cylinder exceeds that of the intake. The backflow into the intake is reduced by having valves in the intake; therefore scavenging efficiency is improved. Furthermore, the asymmetry between the intake and exhaust port timing may be reduced by providing such valves. Additionally, the total intake port area can be increased with two sets of intake ports and valves disposed in the primary ports, thereby improving the volumetric efficiency in spite of the pressure drop presented by the valves.

Abstract: Returning engine oil to the primary oil sump from outboard locations in a flat engine can be a challenge. In the present disclosure, the pressure fluctuations occurring at the underside of the piston, due to reciprocation of the piston, are used to pump the oil from outboard locations to the primary oil sump. To prevent backflow of oil during periods of negative pressure difference, a check valve is placed in the oil drain passage. The check valve allows flow from the outboard location to the primary oil sump and no flow from the primary oil sump to the outboard location by opening and closing as driven by pressure fluctuations due to piston reciprocation. Such a check valve also prevents backflow of the oil to one of the outboard locations when the engine is tilted.

Abstract: In systems in which there is insufficient pressure difference between the intake and the exhaust to drive the EGR, an EGR pump is provided. In a dual-engine system, disclosed herein, the EGR system, i.e., the EGR cooler and EGR pump, is shared to obviate the need for two of each. Shutoff valves may be provided between the EGR system and a secondary of the two engines to isolate the secondary engine when it is not operating. When the engines are OPOC engines, exhaust aftertreatment devices, such as diesel oxidation catalysts and/or diesel particulate filters, may be placed upstream of where the EGR gases tee off from the engine's exhaust to thereby maintain a high pressure ratio across an exhaust turbine located downstream in the engine's exhaust.

Abstract: An opposed-piston, opposed-cylinder OPOC engine is disclosed in which the central axis of the two cylinders is collinear. In four-stroke engines, this is possible with a built up crankshaft. Disclosed are connecting rod configurations that are suitable for a two-stroke engine that can be assembled to a unitary crankshaft, including both pullrods in tension and pushrods in compression. The configuration includes pistons arranged symmetrically, but with offset timing of the intake and exhaust pistons. The offset timing leads to a slight imbalance which can be partially overcome by having the center of gravity of the crankshaft offset from the axis of rotation.

Abstract: An opposed-piston, opposed-cylinder engine in which the intake and exhaust pistons are symmetrically arranged has a small inertial force imbalance in the direction of reciprocation of the pistons. A center of gravity of the crankshaft can be displaced from the axis of rotation to at least partially overcome this imbalance. Such counterweighting of the crankshaft cancels a portion of the inertial balance due to the pistons but introduces an inertial imbalance in an orthogonal direction with respect to the piston-induced imbalance. By providing additional counterweights on pulleys rotating at the same speed, but the opposite direction, as the crankshaft, the imbalance can be substantially eliminated to yield substantially a perfectly-balanced engine.

Abstract: Reciprocating motion can be converted to rotary motion through a crankshaft and a connecting rod. In a joint between a connecting rod and a piston, the connecting rod rocks with respect to the piston. In some situations, the connecting rod is a pullrod always in tension or a pushrod always in compression making it difficult to lubricate the bearing surfaces. A joint is disclosed in which the bearing surfaces rock with respect to each other with no sliding between the surfaces. The connecting rod has a bearing surface that is part of a cylinder having a radius equal to a distance between a central axis of the journal to which the connecting rod is coupled and the bearing surface. The pin has a convexly- or concavely-curved bearing surface and the local radius is based on material properties and the local peak force that the rocking joint is designed to transmit.

Abstract: A piston coupled to a crankshaft via pullrods presents challenges for coupling the piston to the crankshaft because the connections are provided outside the piston. A bridge is coupled to a piston skirt at the end of the piston away from the piston crown. The bridge structure includes: a central support structure, a first projection extending outwardly from the central support structure in a first radial direction, and a second projection extending outwardly from the central support structure in a second radial direction. The central support structure is substantially hollow with a series of internal braces to yield a lightweight piston.

Abstract: A combustion chamber in an opposed-piston, internal-combustion engine is disclosed in which the pistons tops are designed so that when they approach each other, they induce a tumble flow in one or two hemispherical spaces defined in the piston tops. The combustion chamber further includes injectors side mounted in the cylinder wall. In one embodiment, the tumble flows in the two hemispheres are in the same direction and in another embodiment, in opposite directions. In yet another embodiment, there is only one injector and one hemisphere in which a tumble flow is induced.

Abstract: In an electric machine, there may be lubrication and cooling needs, such as lubricating bearings and cooling coils of the electric machine. When lubricant is used for both, it is desirable to prioritize the lubrication to the bearings. By providing check valves between a pressurized oil manifold and the cooling coils, lubricant is diverted to the coils only when pressure in the system is sufficient to satisfy both lubrication and cooling. In some embodiments, an oil gallery is provided on an outside surface of a back iron of the stator of the electric machine and orifices are provided in the back iron so that oil drips onto the coils of the electric motor. In some embodiments, the current commanded to the electric motor is based on whether or not lubricant (or other coolant) is being provided to the coils.

Abstract: Peak performance of an electric motor can be enhanced by effective cooling of windings of the stator to avoid overheating. A liquid coolant is effective at cooling the stator; but in high-speed motors, it is advisable to avoid allowing coolant on the rotor to avoid high frictional losses. A shield provided in the air gap between the rotor and the stator guides the coolant back to a sump without gaining access to the rotor. Furthermore, if the electric machine is proximate a high temperature component, the shield may further prevent radiative and conductive heat transfer to the electric machine.

Abstract: An opposed-piston, opposed-cylinder engine is disclosed that has the pistons symmetrically arranged in the opposed cylinders. In one embodiment, the inner pistons are exhaust pistons and the outer pistons are intake pistons. Alternatively, the inner pistons are intake pistons and the outer pistons are exhaust pistons. The pistons are coupled to the crankshaft that is situated between the opposed cylinders. Central axes of the two cylinders are offset by a predetermined distance. The connecting rods that couple between the crankshaft and the pistons are arranged adjacent to each other on journals of the crankshaft. The journal to which the pushrods couple is not a split-pin type. Instead, it is one that has a common central axis. Furthermore, the crankshaft is a one-piece or unitary structure.

Abstract: In systems in which there is insufficient pressure difference between the intake and the exhaust to drive the EGR, an EGR pump is provided. In a dual-engine system, disclosed herein, the EGR system, i.e., the EGR cooler and EGR pump, is shared to obviate the need for two of each. Shutoff valves may be provided between the EGR system and a secondary of the two engines to isolate the secondary engine when it is not operating. When the engines are OPOC engines, exhaust aftertreatment devices, such as diesel oxidation catalysts and/or diesel particulate filters, may be placed upstream of where the EGR gases tee off from the engine's exhaust to thereby maintain a high pressure ratio across an exhaust turbine located downstream in the engine's exhaust.

Abstract: A toroidal combustion chamber shape with side injectors is being developed for an opposed-piston engine. Favorable combustion characteristics of such configuration are transferred to a conventional engine, i.e., one with a combustion chamber delimited by a piston, a cylinder wall, and a cylinder head. At least one injector is disposed in the cylinder head at the periphery. The fuel is injected substantially along the plane of interface between the cylinder head and the cylinder block. The intake system is configured to provide a swirling flow in the combustion chamber. The fuel is injected in an angle that is displaced from the central axis of the cylinder and directed along the swirl. In some embodiments, a substantially torus-shaped volume is formed between the piston and the cylinder head when the piston is at top center. The injector or injectors spray fuel into the toroidally-shaped volume substantially tangent to the torus.