A hydraulic apparatus including an electronically commutated machine having a plurality of working chambers which are controlled on each cycle of working chamber volume to carry out active or inactive cycles of working chamber volume allows only a plurality of defined fractions of cycles to be active cycles to avoid generating frequencies of active cycles which cause low frequency resonances. The demand signal may be quantised into fractions m/n where n is an integer below a threshold selected to avoid repeating patterns of active cycles of more than a cut-off length.

A hydraulic apparatus including an electronically commutated machine having a plurality of working chambers which are controlled on each cycle of working chamber volume to carry out active or inactive cycles of working chamber volume allows only a plurality of defined fractions of cycles to be active cycles to avoid generating frequencies of active cycles which cause low frequency resonances. The demand signal may be quantised into fractions m/n where n is an integer below a threshold selected to avoid repeating patterns of active cycles of more than a cut-off length.

A fuel pump includes a pump housing with a pumping chamber an inlet valve bore. An inlet valve selectively provides and prevents fluid communication between an inlet of the fuel pump and the pumping chamber. The inlet valve includes an inner housing received within the inlet valve bore such that an outer periphery of the inner housing is sealed to an inner periphery of the inlet valve bore. An outer housing circumferentially surrounds the inner housing. An annular chamber is defined radially between the inner housing and the outer housing and axially between the outer housing and the pump housing. A sealing ring is located within the annular chamber such that the sealing ring is compressed axially against the pump housing and the outer housing.

A fluid-conveying device for conveying a fluid, such as in particular water, from a tank. The fluid can be conveyed along a dosing line to an injection point by a pump, wherein the dosing line is attached at a pressure side of the pump by a connection plug which is attached to an outlet line. The fluid-conveying device has at least one first valve, which is preloaded by a spring and which is configured to prevent a fluid flow from the dosing line to the outlet line and which is furthermore configured to permit the fluid flow from the outlet line to the dosing line if a predefined minimum pressure p1 is reached on that side of the first valve which faces toward the outlet opening.

A compressor includes a cylinder housing having a number of pistons, a control chamber communicating with piston casings, a suction chamber and a discharge chamber communicating with the piston casings, a control valve includes a receptacle engaged in the cylinder housing, a valve member engaged in the receptacle for controlling the pressurized air to flow from the discharge chamber into the control chamber of the cylinder housing, and a valve element for controlling a bypass of the pressurized air through the receptacle. A bellow device is connected to actuate the sliding member internally, and a sliding member is slidably engaged in the control space of the receptacle, and to operate the valve element externally with a solenoid device.

A compressor includes a cylinder housing having a number of pistons, a control chamber communicating with piston casings, a suction chamber and a discharge chamber communicating with the piston casings, a control valve includes a receptacle engaged in the cylinder housing, a valve member engaged in the receptacle for controlling the pressurized air to flow from the discharge chamber into the control chamber of the cylinder housing, and a valve element for controlling a bypass of the pressurized air through the receptacle. A bellow device is connected to actuate the sliding member internally, and a sliding member is slidably engaged in the control space of the receptacle, and to operate the valve element externally with a solenoid device.

A pump mechanism for vacuum sealing an airtight cavity formed by a container and a lid, including a bore having a first one-way seal allowing air from the airtight cavity to enter the bore and blocking air inside the bore from returning to the airtight cavity and a second one-way seal allowing air inside the bore to leave the bore without returning to the airtight cavity and blocking air outside of the bore from entering the bore, a piston disposed inside the bore, and a chamber of air enclosed by the bore, the first and second one-way seals, and the piston, wherein actuation of the piston in a first direction causes air to evacuate the airtight cavity and enter the chamber through the first one-way seal, and wherein actuation of the piston in a second direction causes air to exit the chamber through the second one-way seal.

A pump mechanism for vacuum sealing an airtight cavity formed by a container and a lid, including a bore having a first one-way seal allowing air from the airtight cavity to enter the bore and blocking air inside the bore from returning to the airtight cavity and a second one-way seal allowing air inside the bore to leave the bore without returning to the airtight cavity and blocking air outside of the bore from entering the bore, a piston disposed inside the bore, and a chamber of air enclosed by the bore, the first and second one-way seals, and the piston, wherein actuation of the piston in a first direction causes air to evacuate the airtight cavity and enter the chamber through the first one-way seal, and wherein actuation of the piston in a second direction causes air to exit the chamber through the second one-way seal.

A pump system (120) has a central pump unit (110), with which at least one hook-up unit (130). The least one hook-up unit (130) is from a group of a plurality of hook-up units (130) that can be combined in modular form for setting an operating point of a pump (10) that forms the pump unit (110). A method uses such a hook-up unit (130) in a pump system (120) for setting an operating point of the pump unit (110) thereof. A medical device is provided with such a pump unit (110) or with such a pump unit (110) and at least one hook-up unit (130) combined with the pump unit (110).

A pump system (120) has a central pump unit (110), with which at least one hook-up unit (130). The least one hook-up unit (130) is from a group of a plurality of hook-up units (130) that can be combined in modular form for setting an operating point of a pump (10) that forms the pump unit (110). A method uses such a hook-up unit (130) in a pump system (120) for setting an operating point of the pump unit (110) thereof. A medical device is provided with such a pump unit (110) or with such a pump unit (110) and at least one hook-up unit (130) combined with the pump unit (110).