A piston assembly for an internal combustion engine includes a cylinder bore and a piston having exactly two ring grooves, a scraper ring positioned in the upper ring groove, and an oil control ring positioned in the lower ring groove. A constant twist occurs in the scraper ring about a rotational center of the cross-section, the constant twist occurring at each cross-sectional location of the scraper ring about the circumference of the ring and between adjacent free ends of the ring. The oil control ring can be of a multi-segmented U-flex design, with a coil spring mounted in a channel thereof. The combination of the two rings leads to improved sealing and oil control so that the piston can be manufactured with only two rings, thus reducing overall weight and cost.

A gap seal device includes a housing with a fluid-filled guiding chamber and a multi-part piston that is translationally and/or rotationally moveable in the guiding chamber. The piston separates a high-pressure region from a low-pressure region of the guiding chamber. The piston forms an annular gap having a nominal gap width with an inner wall delimiting the guiding chamber. The piston has a stepped rod, a sleeve, which is slipped over a stepped-down region of the rod and which has a blind hole, and a coupling. The stepped-down region of the rod or in a tube portion of the sleeve includes a stiffness change. A gap width of the annular gap that is reduced compared with the nominal gap width can be set in a region radial to the stiffness change by stress-caused expansion of an outside diameter of the tube portion of the sleeve in accordance with the set stressing force.

A motor vehicle electric motor assembly includes a motor housing having an annular wall extending from a housing first end to an opposite housing second end about a central axis to bound a cavity. The housing first end has a base configured to support a bearing housing. A motor shaft extends along the central axis between a shaft first end and a shaft second end. A rotor is fixed to the shaft for rotation about the central axis. A stator is supported by the annular wall in radially spaced relation from the rotor. A bearing is fixed in the bearing housing to support the shaft first end for rotation about the central axis. An end cover assembly is fixed to the housing second end. The end cover assembly has a motor shaft opening with a periphery of the motor shaft opening supporting the shaft second end for rotation about the central axis.

A piston for a fluid-actuated working cylinder, with a piston base unit which is coaxial to a piston longitudinal axis, consisting of a rigid core body which has radial outer peripheral surface and of an annular filling body which is seated in an annular receiving groove. The receiving groove is coaxial to the piston longitudinal axis and in the region of the radial outer peripheral surface is designed with a radially outwardly facing groove opening in the core body. The piston further includes a ring element which consists of plastic. The ring element radially outwardly coaxially encompasses the piston base unit at least in the region of the filling body, being radially supported with a radial inner peripheral surface on the piston base unit, projecting radially beyond the radial outer peripheral surface of the core body and comprising an axially orientated axial support surface radially outside the piston base unit on its two axial face sides. The piston further includes an annular enveloping body which has rubber elastic characteristics.

The present disclosure provides an open-faced piston with a circumferential groove into which a piston ring assembly is arranged. Openings at the bottom of the circumferential groove and between a front land of the open-faced piston and the piston face are provided. The openings are arranged to allow for a combustion reaction to propagate through the volume defined between the bottom of the piston ring assembly and the piston face such that at least a portion of an air and fuel mixture located in that volume is reacted.

A piston for a compressor includes a bearing portion having a cylindrical shape to define a suction space into which refrigerant is accommodated therein, the bearing portion being provided with a bearing surface facing an inner circumferential surface of the cylinder, a head portion coupled to a front opening of the bearing portion and provided with a plurality of suction ports which communicate with the suction space, the head portion having a compression surface configured to face a compression space to compress the refrigerant in the compression space, and a flange portion coupled to a rear opening of the bearing portion and provided with a through-passage through which the refrigerant is introduced from a muffler unit to the suction space, the flange portion being coupled to a driving portion to transmit driving force to the piston. The bearing surface is subjected to a surface treatment to improve abrasion resistance.

An internal combustion may include a cylinder having a first combustion chamber at one end and a second combustion chamber at an opposing end, first and second cylinder heads located at an end of the first and second combustion chambers, respectively, and a double-faced piston slidably mounted therein. The piston may be configured to move in a first stroke that includes an expansion stroke portion and a non-expansion stroke portion. The engine may further include first and second piston rod portions extending from opposite faces of the piston. A recess in the piston rod portions may be configured to communicate gases between a combustion chamber and locations outside the cylinder. There may also be a chamber surrounding the first or second piston rod portion, the chamber configured to be supplied with gas and the chamber being isolated from the first combustion chamber and the second combustion chamber.

Provided is a plunger including: a plunger body; a first surface configured to come into contact with an inner peripheral surface of the cylindrical member; a second surface disposed on a base end side relative to the first surface, the second surface having an outer diameter that is smaller than that of the first surface; an outer stepped surface disposed between the first surface and the second surface; a first housing disposed in an area at least partly corresponding to the second surface in the recess, the first housing being provided for housing a tip part of the pin; a second housing disposed on the base end side relative to the first housing, the second housing having an inner diameter that is smaller than a largest inner diameter of the first housing; and an inner stepped surface disposed between the first housing and the second housing.

A piston includes an annular body including a crown portion defining a longitudinal axis, a radial direction perpendicular to the longitudinal axis, and a circumferential direction. The crown portion includes a top squish surface, and a circumferential annular wall extending downwardly axially from the top squish surface as well as a skirt. A first piston ring receiving groove is spaced away from the top squish surface, an upper land and a lower land extend from the first piston ring receiving groove, and a bottom blend connects the lower land to the first piston ring receiving groove.

A wear-preventive air-charger piston structure is provided. The piston rod has a top forming a piston top seat on which a piston ring is disposed. The piston ring is covered with a top cover that is combined with the piston top seat. The top cover is provided with an airtight plate mounted thereto to form a complete piston structure. A buffering element is arranged between the piston top seat and the piston ring. The buffering element has an outside diameter smaller than the piston ring, so that when the piston ring, which is driven by a crankshaft to do an up-and-down movement, is put in an inclined oscillating condition and at a high position of an oscillation side, the buffering element functions to absorb the stress acting on the piston ring at the high position of the oscillation side to effectively prevent detachment and breaking of the piston ring.