Abstract: The invention relates to an electropneumatic position controller having a controllable valve group (9, 10, 13) arranged in the position controller and having at least one valve (9, 10), by means of which in normal operation either compressed air supplied by means of a compressed air supply line (6) can be fed to an exhaust connection (8) or air fed by means of the exhaust connection (8) can be discharged to the outside, depending on the actuation of the valve group. In order for the valve group to be brought in a safe position, even in the event of a leak in one of the components thereof, said group is arranged in a gas-tight housing (14) within the position controller and means (15) are provided for monitoring the pressure in the housing (14) and for actuating the valve group (9, 10, 13) such that if the pressure in the housing (14) exceeds a predefined threshold value, said group is brought in the predefined safe position.

Abstract: The invention relates to an electropneumatic position controller having a controllable valve group (9, 10, 13) arranged in the position controller and having at least one valve (9, 10), by means of which in normal operation either compressed air supplied by means of a compressed air supply line (6) can be fed to an exhaust connection (8) or air fed by means of the exhaust connection (8) can be discharged to the outside, depending on the actuation of the valve group. In order for the valve group to be brought in a safe position, even in the event of a leak in one of the components thereof, said group is arranged in a gas-tight housing (14) within the position controller and means (15) are provided for monitoring the pressure in the housing (14) and for actuating the valve group (9, 10, 13) such that if the pressure in the housing (14) exceeds a predefined threshold value, said group is brought in the predefined safe position.

Abstract: A two-stage servo-valve has a first stage in which four flow resistances are arranged in a bridge circuit. At least one of the flow resistances is variable, and two opposite switching points of the bridge circuit are connected to an air inlet and to an air outlet respectively. A differential pressure of variable size and sign is provided between the two other switching points. The servo-valve also has a second stage in which a control piston which can be actuated by the differential pressure is arranged and controls a three-way valve. In order to enable the current position of a process valve driven by the servo-valve to be maintained by the most simple means in the event of a power failure, the switching points which provide the differential pressure are interconnected by a magnetic valve which is closed in the driven state and open in the unconnected state, thus pneumatically interconnecting the switching points.

Abstract: A valve having at least one first valve chamber (1) which has an inlet opening (2) for the supply of a medium and a valve opening (3) which can be closed off by means of a valve body (4), which valve body (4) is acted on by a spring force (F K) which acts in the closing direction and which is generated by a force store (9) which has a spring constant and which valve body (4) can be adjusted counter to the spring force (F K) by means of an actuating element (5) to which an actuating force (F S) which acts counter to the spring force (F K) can be applied at an action point (10), is characterized in that means (7, 8) are provided, by way of which the spring constant which acts at the action point (10) of the actuating force (F S) can be set.

Abstract: There is described a 3-port directional control valve having a first valve chamber, a second valve chamber and a third valve chamber, wherein a first fluid passage, which can be closed off by means of a first adjustable valve body, is provided between the first valve chamber and the second valve chamber, and a second fluid passage, which can be closed off by means of a second adjustable valve body, is provided between the second valve chamber and the third valve chamber. The first valve body and the second valve body are arranged on an actuating element which is mounted so as to be rotatable about at least one rotational axis, so that the adjusting movements of the valve bodies take place in opposition to one another. A diaphragm is arranged between the valve bodies, and the actuating element, herein the effective area of the diaphragm is matched to the effective cross section of the respective valve body for the purpose of force equalization.

Abstract: A two-stage servo-valve has a first stage in which four flow resistances are arranged in a bridge circuit. At least one of the flow resistances is variable, and two opposite switching points of the bridge circuit are connected to an air inlet and to an air outlet respectively. A differential pressure of variable size and sign is provided between the two other switching points. The servo-valve also has a second stage in which a control piston which can be actuated by the differential pressure is arranged and controls a three-way valve. In order to enable the current position of a process valve driven by the servo-valve to be maintained by the most simple means in the event of a power failure, the switching points which provide the differential pressure are interconnected by a magnetic valve which is closed in the driven state and open in the unconnected state, thus pneumatically interconnecting the switching points.

Abstract: A positioner for a valve that is actuated by means of a drive. The positioner includes a locator (9) and a control unit (13). The locator (9) detects the actual position of an actuator (7). The control unit (13) compares the actual position with a predefined desired position, and generates an actuating signal. A magnet (18) having a magnetoresistive sensor, preferably a GMR sensor, is provided as the locator. The locator (9) is less susceptible to dirt and less prone to wear and tear than a conventional slide potentiometer. The positioner is thus less fault-prone.

Abstract: A position controller including a position transmitter (9) and a control unit (13). The position transmitter detects the actual position of an actuator (7). The control unit (13) is arranged in an ignition-proof enclosure that is separate from the housing of the position transmitter (9). The interface (18) between the control unit (13) and the position transmitter (9) as well as the position transmitter (9) itself—which comprises a magnet (10) and a magnetoresistive sensor (50)—have an inherent electrical safety design.

Abstract: A position controller including a position transmitter (9) and a control unit (13). The position transmitter detects the actual position of an actuator (7). The control unit (13) is arranged in an ignition-proof enclosure that is separate from the housing of the position transmitter (9). The interface (18) between the control unit (13) and the position transmitter (9) as well as the position transmitter (9) itself—which comprises a magnet (10) and a magnetoresistive sensor (50)—have an inherent electrical safety design.

Abstract: A positioner for a valve that is actuated by means of a drive. The positioner includes a locator (9) and a control unit (13). The locator (9) detects the actual position of an actuator (7). The control unit (13) compares the actual position with a predefined desired position, and generates an actuating signal. A magnet (18) having a magnetoresistive sensor, preferably a GMR sensor, is provided as the locator. The locator (9) is less susceptible to dirt and less prone to wear and tear than a conventional slide potentiometer. The positioner is thus less fault-prone.

Abstract: A print head consists of an ink chamber with heater elements and orifices. Connected to the ink chamber is a pump chamber which is supplied with ink through an ink supply opening. The ink chamber and the pump chamber are enclosed between a first and a second end plate. The pump element is integrated within the pump chamber which forms part of the print head and there are divider elements and valve elements arranged lengthways along both sides of the pump element.

Abstract: An optical scanning device, which includes a transparent support plate having a supporting surface on which an original is positioned, a scanner carriage being mounted for transverse movement below the support plate on two guide elements extending parallel to each other characterized by the guide elements being frame parts having surfaces forming the guide tracks for the carriage and also having surfaces facing the guide tracks for engaging the supporting surface of the support plate so that the distance between the supporting surface and the scanner is determined by the position of the seating surface relative to the guide track.