Abstract: A filter device may include a filter housing having at least one filter element configured to separate the filter housing into a raw side and a clean side. A bypass valve may control a bypass for circumventing the at least one filter element, wherein the bypass valve may have a valve member for controlling a bypass opening connecting the clean side of a coupling chamber of the bypass valve with the raw side. The valve member may be configured to close the bypass opening via a pretension generated by a closing spring. The bypass valve may be an actuating device for changing the pretension acting on the valve member and the actuating device may be coupled with at least one control chamber and configured to set the pretension acting on the valve member based at least in part on a control pressure of the control chamber.

Abstract: A differential pressure measurement device may include a piston arranged in a cylinder and configured to define a first pressure space from a second pressure space within the cylinder. A first piston rod may be fixed to the piston and guided through the first pressure space out of the cylinder. A pressure sensor may be configured to interact with the first piston rod to measure a compressive force with which the first piston rod presses against the pressure sensor. A second piston rod may be fixed to the piston and guided through the second pressure space out of the cylinder. The chamber may be connected to a surface section of the pressure sensor which interacts with the first piston rod.

Abstract: A filter device may include a filter housing having at least one filter element configured to separate the filter housing into a raw side and a clean side. A bypass valve may control a bypass for circumventing the at least one filter element, wherein the bypass valve may have a valve member for controlling a bypass opening connecting the clean side of a coupling chamber of the bypass valve with the raw side. The valve member may be configured to close the bypass opening via a pretension generated by a closing spring. The bypass valve may be an actuating device for changing the pretension acting on the valve member and the actuating device may be coupled with at least one control chamber and configured to set the pretension acting on the valve member based at least in part on a control pressure of the control chamber.

Abstract: A particle counter that operates according to the blackout and/or light blockade method for counting foreign particles in a fluid stream, in particular in a hydraulic fluid stream, has a photoelectric barrier whose beam of light penetrates through a measurement channel through which a bypass substream of the fluid stream flows and has an electronic analyzer downstream from the receiver of the photoelectric barrier. To this end, such a particle counter includes a pressure regulating device acting on the fluid stream forces a predefined pressure difference which is independent of the flow properties of the main fluid stream onto the area situated between the inlet and outlet of the measurement channel. (11), The particle counter includes a heating or cooling device for regulating the temperature of the substream flowing through the measurement channel at a predetermined temperature level.