A pivoting piston machine includes a housing, a first piston and a second piston arranged in the housing, the first and second pistons being pivotable away from one another and toward one another about a pivot axis. The machine has a working chamber arranged between first and second piston. The working chamber increases and decreases in size in alternating fashion during pivoting of the first piston and of the second piston. The machine also has a inlet mouth for admission and discharge of the working medium. A closing element for closing and opening the inlet or the outlet has a valve disk interacting with a valve seat. Either the inlet mouth or the outlet mouth is arranged within the working chamber between the first end surface and the second end surface, and the valve seat and the valve disk are arranged at either the inlet mouth or the outlet mouth.

A method for manufacturing an engine poppet valve having a valve head portion and a stem portion made integral by way of a neck portion that increases in diameter toward a tip end, comprising: a valve head portion manufacturing operation in which hot forging is employed to form a stem/head intermediate product comprising an intermediate stem portion and a valve head portion which is made integral with the intermediate stem portion by way of a neck portion; a stepped stem portion manufacturing operation in which cold drawing in which a part of the intermediate stem portion is inserted in press-fit fashion from a base end portion into a stem member inlet surface and a stem member compressing surface of a hollow circular hole die that has a drawing hole and at which the stem member inlet surface that gradually narrows toward a central axis, and the stem member compressing surface that is continuous with the stem member inlet surface and that has a constant inside diameter which is less than an outside diameter of the intermediate stem portion are provided at least at a portion thereof is employed to cause a stepped stem portion comprising a first stem portion which has been made to be of decreased diameter, a step portion which has been formed by the stem member inlet surface, and a second stem portion in which there is absence of decrease in diameter and which is continuous by way of the step portion with the first stem portion to be formed from the intermediate stem portion; and a joining operation in which a stem end portion having a same outside diameter as the first stem portion is joined to a base end portion of the first stem portion.

At a diameter-decreasing operation during manufacture of a poppet valve, an intermediate stem portion at which a valve head portion and an intermediate stem portion are made integral by way of a neck portion may be inserted between/among diameter-decreasing tools. Application of compressive forces from compressing surfaces of the diameter-decreasing tools may cause a part of the intermediate stem portion to be decreased in diameter and may cause a main body portion of a first stem portion to be formed and may cause formation of a stepped portion which is continuous with the main body portion, and formation, by an absence of decrease in diameter, of a second stem portion which is broader in girth than the main body portion and which is continuous with the neck portion and which is also continuous with the main body portion by way of the stepped portion.

At a diameter-decreasing operation during manufacture of a poppet valve, an intermediate stem portion at which a valve head portion and an intermediate stem portion are made integral by way of a neck portion may be inserted between/among diameter-decreasing tools. Application of compressive forces from compressing surfaces of the diameter-decreasing tools may cause a part of the intermediate stem portion to be decreased in diameter and may cause a main body portion of a first stem portion to be formed and may cause formation of a stepped portion which is continuous with the main body portion, and formation, by an absence of decrease in diameter, of a second stem portion which is broader in girth than the main body portion and which is continuous with the neck portion and which is also continuous with the main body portion by way of the stepped portion.

A method for expanding a compressed gas (GD) at a gas pressure (pD) with a reciprocating-piston machine, wherein the reciprocating-piston machine includes a piston that can move to and fro and a working chamber delimited by the movable piston. The method being carried out as follows: the compressed gas (GD) is supplied to the working chamber via an actuatable rotary slide valve, wherein the compressed gas (GD) in the working chamber is expanded in the working chamber.

A valve system that includes a housing defining an intake port, a cylinder port and a valve bore; wherein the intake port defining a valve seat portion at an interface between the intake port and the cylinder port. The valve system also includes a valve to control fluid communication between the intake port and the cylinder port. The valve includes a valve stem disposed within the valve bore and extending into the cylinder port and extending out of the housing, the valve stem having an open face exposed to atmospheric pressure and a valve head coupled to the valve stem comprising a first face and an opposing second face. A diameter of the valve stem is selected to control a closing force on the first face of the valve head.

A valve system that includes a housing defining an intake port, a cylinder port and a valve bore; wherein the intake port defining a valve seat portion at an interface between the intake port and the cylinder port. The valve system also includes a valve to control fluid communication between the intake port and the cylinder port. The valve includes a valve stem disposed within the valve bore and extending into the cylinder port and extending out of the housing, the valve stem having an open face exposed to atmospheric pressure and a valve head coupled to the valve stem comprising a first face and an opposing second face. A diameter of the valve stem is selected to control a closing force on the first face of the valve head.

A multi-valve for a cooling system of a motor vehicle includes: a valve housing, which has a plurality of inlets and a plurality of outlets and delimits a cylindrical valve chamber, the plurality of inlets and the plurality of outlets opening into the cylindrical valve chamber; and a valve unit, which is arranged inside the cylindrical valve chamber of the valve housing and is rotatable about an axis of rotation between a plurality of switching positions by an actuator. Depending on a switching position of the valve unit, different inlets of the plurality of inlets are fluidically connectable to different outlets of the plurality of outlets. The valve unit has a plurality of fluid channel structures which are offset from one another in a circumferential direction. Each switching position of the plurality of switching positions is respectively assigned a fluid channel structure of the plurality of fluid channel structures.

A multi-valve for a cooling system of a motor vehicle includes: a valve housing, which has a plurality of inlets and a plurality of outlets and delimits a cylindrical valve chamber, the plurality of inlets and the plurality of outlets opening into the cylindrical valve chamber; and a valve unit, which is arranged inside the cylindrical valve chamber of the valve housing and is rotatable about an axis of rotation between a plurality of switching positions by an actuator. Depending on a switching position of the valve unit, different inlets of the plurality of inlets are fluidically connectable to different outlets of the plurality of outlets. The valve unit has a plurality of fluid channel structures which are offset from one another in a circumferential direction. Each switching position of the plurality of switching positions is respectively assigned a fluid channel structure of the plurality of fluid channel structures.

A valve assembly for an engine includes a gas exchange valve, a valve guide, and a seal. The gas exchange valve includes a valve stem. The valve guide includes an outer surface having a stem seal retention surface disposed at a seal end thereof. The valve stem extends through the valve guide such that the valve is reciprocally movable over a range of travel along the longitudinal axis with respect thereto. The seal is mounted to the stem seal retention surface of the valve guide such that the seal is in running, sealing engagement with the valve stem. The stem seal retention surface includes a shoulder surface to help retain the seal.