A piston engine may include a clearance gap between a piston assembly and a cylinder. The piston may be configured to translate in a bore of the cylinder. The clearance gap between the piston assembly and the bore may be actively or passively controlled. A control system may provide one or more adjustments based on, for example, a detected temperature, pressure, flow rate, work metric, and/or other indicator. The adjustments may include, for example, adjusting a cylinder liner, adjusting a flow through a bearing element, adjusting a coolant flow, adjusting a heat pipe property, and/or other adjustments. One or more auxiliary systems may be used to provide the adjustments.

A fluid actuator includes housing defining a cylinder bore and first and second fluid passages. A circumferential detent groove extends into the housing from the cylinder bore. The cylinder bore receives a piston having a top face and a skirt in sliding engagement. A circumferential detent ring groove extends radially inwardly into the skirt. The detent ring groove has a first portion of a first depth and a second portion of a second, greater depth. An o-ring is at least partially received in the second portion. A wear ring is at least partially received in the first portion and overlies the o-ring. The o-ring biases the wear ring outwardly of the detent ring so that the wear ring may be selectively engaged with the detent groove.

A fluid actuator includes housing defining a cylinder bore and first and second fluid passages. A circumferential detent groove extends into the housing from the cylinder bore. The cylinder bore receives a piston having a top face and a skirt in sliding engagement. A circumferential detent ring groove extends radially inwardly into the skirt. The detent ring groove has a first portion of a first depth and a second portion of a second, greater depth. An o-ring is at least partially received in the second portion. A wear ring is at least partially received in the first portion and overlies the o-ring. The o-ring biases the wear ring outwardly of the detent ring so that the wear ring may be selectively engaged with the detent groove.

An assembly method of a piston-cylinder group (10), where the piston-cylinder group (10) includes a cylinder (20) at an end of which a head (40) is fixable, provided with seal gaskets (43). The method includes the steps of: mounting the seal gaskets (43) in appropriate seatings in the head (40); coupling the head (40) with the cylinder (20); and a low-temperature welding of the coupling between the head (40) and the cylinder (20).

A pneumatic cylinder includes a cylinder body, a piston assembly, a connecting rod, and at least one pressure-relief valve. The cylinder body is formed with a cylinder chamber, and has an exterior disposed with at least one inlet-outlet passage and at least one pressure-relief opening, wherein the inlet-outlet passage is connected to the cylinder chamber. The piston assembly is contained within the cylinder chamber. The connecting rod is connected to the piston assembly, and protrudes out from the cylinder body. The pressure-relief valve is disposed in the pressure-relief opening, and has two ends connected to an outside of the pneumatic cylinder and the cylinder chamber respectively. When a gas pressure within the cylinder chamber is greater than a threshold value, the pressure-relief valve works to allow the cylinder chamber connecting to the outside for pressure relief.

In order to provide a master cylinder, in particular for a clutch system, an actuating system or a braking system of a vehicle, which enables secure sealing of the cylinder chamber relative to the outside, as well as a reliable flow of hydraulic medium into the cylinder chamber, it is proposed that the piston comprises a first section which has a cylindrical lateral surface and a second section which has at least one region which is set back radially inwardly with respect to the cylindrical lateral surface of the first section, wherein at least one set-back region extends to an end of the piston and wherein the first and second sections are arranged on the piston in such a way that in an actuating position of the piston, the main sealing element in the first section of the piston abuts in sealing manner thereagainst and in the pressure equalization position of the piston, in the second section of the piston between the piston and the main sealing element, at least one gap is formed, through which hydraulic medium can flow along the piston from the supply chamber into the cylinder chamber in order to equalize the pressure.

In order to provide a master cylinder, in particular for a clutch system, an actuating system or a braking system of a vehicle, which enables secure sealing of the cylinder chamber relative to the outside, as well as a reliable flow of hydraulic medium into the cylinder chamber, it is proposed that the piston comprises a first section which has a cylindrical lateral surface and a second section which has at least one region which is set back radially inwardly with respect to the cylindrical lateral surface of the first section, wherein at least one set-back region extends to an end of the piston and wherein the first and second sections are arranged on the piston in such a way that in an actuating position of the piston, the main sealing element in the first section of the piston abuts in sealing manner thereagainst and in the pressure equalization position of the piston, in the second section of the piston between the piston and the main sealing element, at least one gap is formed, through which hydraulic medium can flow along the piston from the supply chamber into the cylinder chamber in order to equalize the pressure.

The present disclosure relates to a piston-cylinder unit with a cylinder jacket and a piston rod longitudinally shiftably guided in the cylinder jacket as well as an evaluation unit which determines the position of the piston rod with respect to the cylinder jacket by the intrinsic electrical properties of an interconnection of cylinder jacket, piston rod and piston, wherein the piston rod is short-circuited against the cylinder or the cylinder head in a manner suitable for high frequencies via one or more contact elements in the region of the exit opening of the piston rod out of the cylinder head.

The present disclosure relates to a piston-cylinder unit with a cylinder jacket and a piston rod longitudinally shiftably guided in the cylinder jacket as well as an evaluation unit which determines the position of the piston rod with respect to the cylinder jacket by the intrinsic electrical properties of an interconnection of cylinder jacket, piston rod and piston, wherein the piston rod is short-circuited against the cylinder or the cylinder head in a manner suitable for high frequencies via one or more contact elements in the region of the exit opening of the piston rod out of the cylinder head.

A cylinder head includes a plurality of exhaust ports provided corresponding to a plurality of cylinders, and configured to converge outlets of the exhaust ports inside the cylinder head, at least one of the exhaust ports not being provided with a water jacket there above, and a pair of oil passages arranged so as to sandwich the at least one of the exhaust ports above which the water jacket is not provided. An inclined surface provided on an upper surface of the cylinder head and positioned between the pair of oil passages, the inclined surface being inclined from one oil passage, of the pair of oil passages, toward the other oil passage.