Abstract: Pump or motor having a rotor with chambers with a through rotation variable volume which are connectable via switches to either a first line connection or a second line connection. During switching between the line connections, the volume of the chamber changes and to avoid pressure peaks or cavitation the chambers are interconnected with connecting lines. Each connecting line has closures to stop the flow through the connecting line after a limited volume of fluid has passed in one direction.

Abstract: The invention relates to an apparatus for executing activities assisted by equipment driven by means of rotating or linear hydromotors. The hydromotors may be loaded and/or moved in two directions. The hydromotors are coupled via a connecting line and a hydraulic transformer with a high-pressure line. The hydraulic transformer is provided with adjusting means for controlling the hydromotor and control means are provided for restricting the fluid flow in the hydraulic transformer.

Abstract: The invention relates to a hydraulic device provided with a housing having at least a first line connection and a second line connection and, if appropriate, further line connections, a rotor which can rotate in the housing and chambers which are alternately connected to one of the line connections as a result of the rotation of the rotor. According to the invention, chambers are connected by connecting lines in which there are means for closing a connecting line after a limited volume of fluid has flowed through the connecting line in one direction.

Abstract: The invention relates to a free-piston unit for pumping fluid from a low pressure to a high pressure. The free piston is displaced by a hydraulic part under the influence of the fluid pressure on a plunger which is connected to a combustion piston. The force exerted on the plunger by the fluid pressure in a pressure chamber during the compression stroke can be set using conversion means by setting a third pressure for fluid which is to be displaced via a pressure chamber from the first fluid source to the second fluid source.

Abstract: A hydraulic installation comprising a hydraulic motor for linearly or rotatively moving against a load, a first connection with a source of pressurized hydraulic fluid of mainly constant high pressure, a second connection with a source of pressurized hydraulic fluid of mainly constant low pressure, a hydraulic transformer for transforming a flow of hydraulic fluid of a first pressure into a flow of hydraulic fluid of a second pressure and connected to the first connection and the second connection and at least one connecting line connecting the hydraulic motor and the hydraulic transformer, the hydraulic transformer comprising a housing, a rotor freely rotatable in the housing, chambers in the rotor with means for changing the volume of the chambers between a minimum and a maximum value during a full rotation of the rotor and means for alternately connecting each chamber with the first connection, the second connection and the connecting line, and wherein the hydraulic motor and the hydraulic transformer are

Abstract: A free piston combustion engine and method by which additional combustion air is supplied by a charge air system. The charge air system includes a piston-cylinder charge air pump in which the piston is movable independently of the movement of the free piston. The charge air pump may be hydraulically driven.

Abstract: A hydraulic system includes a hydraulic transformer with a rotor which is coupled with the hydromotor. The hydromotor may be subjected to a variable load which has to be moved in different directions. By using various switching means, the combination hydromotor and hydraulic transformer has been made suitable for the necessary four-quadrant operation.

Abstract: The invention relates to a pressure transformer for the conversion of a hydraulic power from a first fluid flow having a first pressure into the hydraulic power of a second fluid flow having a second pressure. In the housing (3) a rotor (26) is mounted, able to rotate around a rotation shaft (4) due to the effect of the pressure differences between the three pipe connections (16). Around the rotation shaft chambers (24) are distributed comprising displacement means (27, 29) such as pistons (27) which, when the rotor (26) in the housing (3) rotates, vary the volume in the chambers (24) between a minimum and a maximum value, and channels (19, 22) provided with valves (20, 21) activated by the rotation of the rotor (26) and connecting each chamber (24) alternately with the first, the second and the third pipe connection (16).

Abstract: An hydraulic switching valve (35) comprises, among other parts, a valve housing (45, 62) with a first connection (33, 36) and a second connection (34, 67) and a valve body (37, 63) which is movable in the valve housing (45). The switching valve (35) is open when the pressure at the first connection (33) is higher than the pressure at the second connection (34) as a result of the fact that the pressure difference caused by the movement of the valve body (37) allows a flow past the valve body (37). The switching valve is closed when the pressure at the first connection (33) is lower than the pressure at the second connection (34) as a result of the fact that the movement of the valve body (37) caused by the pressure difference closes a valve seal (40) which blocks the flow. The switching valve (35) further comprises a lock (39) with switching element (42) for selectively keeping the valve seal (40) closed, and unblocking the valve body (37), respectively.

Abstract: A free-piston engine comprises a combustion part (1), a hydraulic control system (2), an energy consumption system and an engine control system. The combustion part comprises a combustion cylinder with at least one combustion piston (4). The hydraulic control system (2) comprises a hydraulic piston (24) which, together with a combustion piston (4), forms a piston assembly, and which has a first surface that, when under hydraulic pressure, exerts a force on the piston assembly (24) that is directed towards the combustion space (6) and a second surface, smaller than the first surface, that, when under hydraulic pressure, exerts a force on the piston assembly that is directed away from the combustion space.

Abstract: A free-piston engine having a fluid energy unit comprises a cylinder and a piston reciprocating within the cylinder. The piston is equipped with a plunger-shaped extension including a first axial face moving within a chamber when the piston is moved. There are supply means for supply of liquid from a reservoir to the chamber and discharge means for discharge of fluid from the chamber to an accumulator. The plunger-shaped extension further comprises an axial face opposite the first axial face and bordering a pressurized room in the top dead center of the piston. The hydraulic unit further includes a compression section for making a compression stroke of the piston. The discharge means include separate first and second discharge channels. The first discharge channel connects to the chamber in such a manner that a discharge of liquid from the chamber to the accumulator can take place only in a first part of the expansion stroke of the piston and the first discharge channel having a low flow resistance.

Abstract: The invention relates to a method for the cold start of a free-piston diesel engine, comprising a cylinder having a combustion room therein and an air inlet, fuel supply and combustion gas outlet connected thereto, and a piston movable within the cylinder and limiting one side of the combustion room. Energy is supplied to the piston to compress air supplied through the inlet by reducing the combustion room, whereafter fuel is injected to allow the fuel-air mixture to ignite by spontaneous combustion. So much compression energy is delivered to the piston that the combustion room is reduced to a volume of less than 3% of the combustion room volume when the outlet is closed. The corresponding free-piston engine has a dead volume of less than 3%.

Abstract: A free piston engine having a fluid pressure unit which includes a cylinder and a piston arranged within the cylinder and reciprocating therein between the bottom dead center and the top dead center. The piston includes a plunger-shaped piston extension cooperating with the fluid pressure unit. This fluid pressure unit is equipped with an auxiliary member for moving the piston in a direction to its bottom dead center. This auxiliary member includes a connecting channel adapted to communicate a liquid pressure source with a room in which the plunger-shaped piston extension extends and which room is closed on one side by an axial face of the piston extension which is directed such that, by pressure loading the axial face, the piston is moved towards the bottom dead center. The axial face is formed on a ring slidably arranged on the plunger-shaped extension. The plunger-shaped extension includes a stop adapted for engagement by the ring when it is moved for displacing the piston to its bottom dead center.

Abstract: A free-piston engine having a fluid pressure unit, comprises a cylinder and a piston arranged therein. The piston is equipped with a plunger-shaped extension including a working section having a room bordered by a first axial face of the plunger-shaped extension and the volume of which is reduced when the piston makes an expansion stroke, and to which a discharge channel to a high pressure accumulator and a supply channel from a supply reservoir connects. The piston further includes a compression section including a chamber having a first chamber portion enclosed by a second axial face in the bottom dead center of the piston and a second chamber portion bordered by a third axial face.