Abstract: The invention concerns a frequency converter for an electromotor with an intermediary circuit, in which a braking circuit with a switch and a load is arranged. With such a frequency converter, it is possible to ease the demands on protection measures, even though the load is placed outside the frequency converter. For this purpose the load is galvanically separated from the intermediary circuit.

Abstract: A hydraulic function-performing unit is described, having a main housing and at least one movable function-performing element, the position and/or movement of which in the main housing determines flow and/or pressure conditions and/or chamber volumes for hydraulic fluid, and having at last one sensor. It is desirable for the construction of such a function-performing unit to be simplified. To that end, the sensor is accommodated inside a sensor housing. The sensor housing and the main housing have adjoining interface faces and there is provided a transmission channel which is led through the interface face and connects a measuring point in the main housing to the sensor.

Abstract: Hydraulic vane machine with a stator having a stator bore with a guiding contour, a rotor arranged in the stator bore and having substantially radially movable vanes bearing on the guiding contour, and a shaft connected fixedly rotatable with the rotor via a coupling. In such a machine the operation behaviour must be improved. For this purpose the coupling has a transmission element located horizontally with the shaft being vertical. The transmission element is radially displaceable relative to the shaft in one direction and is laterally displaceable relative to the rotor in a second direction.

Abstract: The invention concerns a hermetic cooling compressor with an electric motor having a variable speed controlled by a converter cooled by a cooling medium flow. The compressor and the converter are formed together as a unit, in which a medium flowing through the unit is used for cooling of the electronic circuit of the converter. Thus the electronic circuit can be made without bulky cooling plates.

Abstract: A method for the field-oriented control of an induction motor (2) by means of a frequency converter (1) is disclosed, in which method a transformation angle (.delta.) is determined by estimation and is corrected in dependence on a rotational speed (.omega..sub.mR) of a rotor flux vector (i.sub.mR) or of the induction motor (2) and/or in dependence on a delay time (T.sub.del). In this connection it is desirable to improve the control behavior. To that end, the transformation angle (.delta.) is corrected a second time to compensate for a phase shift in the frequency converter (1).

Abstract: Method for commutation of a brushless motor being supplied with electrical energy from a DC intermediary circuit via a multi-phase inverter, by which a first current and a second current value are determined and the length of a commutation interval is set in dependence of these current values. With motors being exposed to heavily varying load torques during one rotation, e.g. motors driving a compressor, a stable operation must be reached. For this purpose a correction value is added to the pre-set commutation interval determined by the speed of the motor, said correction value being the result of the difference of the actual value of the intermediary circuit current and a filtered and delayed value of the intermediary circuit current, multiplied by a weighting factor.

Abstract: A hydraulic vane machine has a rotor, in which several vanes are arranged radially movable, and a stator having a stator bore, whose wall is made as a guiding contour on which the vanes bear. It is intended to prolong the life of such a machine, even when the machine is operated with a poorly lubricating hydraulic fluid, such as water. For this purpose at least one vane has a wearing surface on the end bearing on the guiding contour. Further, a channel arrangement is provided between high pressure and low pressure sides of the vane, which channel is blocked as long as the wearing surface has a predetermined thickness, and opened when the wearing surface is thinner than the predetermined thickness.

Abstract: In a method for controlling the superheat temperature (T.sub.u) of the refrigerant in an evaporator arrangement (1) of a refrigeration system or heat pump system (1-4), the evaporator arrangement (1), a compressor arrangement (2), a condenser and a controllable expansion valve (4) are arranged in succession in a closed circuit. The superheat temperature (T.sub.u) is controlled in dependence on a comparison between desired and actual values. The desired value (W.sub.2) of the superheat temperature (T.sub.u is varied automatically in dependence on the difference (d) from a reference value (W.sub.1) of a periodically determined function (S) of a number of sampled values of a temperature (T.sub.1 ; T.sub.2) of the refrigerant with the aim of a stable control of the superheat temperature (T.sub.u). To achieve optimum filling and to optimize the superheating in such systems, provision is made for the said function (S) to characterize the variability of a number of sampled values of the temperature (T.sub.

Abstract: A suction sound damper for a refrigerant compressor is disclosed, having an inlet, which is arranged to be connected to a suction port, and an outlet, which is arranged to be connected to the refrigerant compressor, and also having at least one damping volume. It is desirable for a suction sound damper of that kind to be of simple and inexpensive construction, and to contribute to increasing the efficiency of a refrigerant compressor. For that purpose, it is formed from a first and second half which define an internal space in which the damping volume is arranged, the first half having projecting into the internal space a gas deflection wall which, at least over sections thereof, forms a lateral limitation of a flow path free from throttle points between inlet and outlet.

Abstract: A hydraulic control device is disclosed, having a pressure connection and a tank connection and having a metering pump unit (4) that comprises at least two metering pumps (5, 6) connected hydraulically in parallel and operable mechanically in parallel and also a cut-off valve (8) in hydraulic connection between the two metering pumps (5, 6), the cut-off valve (8) being flange-mounted on a metering pump (6) and having in a housing (13) a slider member (12) which, under pressure form the pressure connection (P), is movable axially towards the metering pump (6). It is desirable to keep wear and tear to a low level such a control device. For that purpose, a displacement-limiting device (26, 28) for the slider member (12) is provided, which prevents the slider member from bearing on the metering pump (6).

Abstract: A process for controlling a refrigeration system, as well as the refrigeration system and a new expansion valve for the refrigeration system. An electronic regulator is used to operate a sensor system having a device for applying heat power to the sensor system in direct dependence on sensed superheat of the refrigerant leaving the evaporator. By locating the sensing system in communication with liquid refrigerant upstream of the evaporator, heat transfer to the liquid refrigerant is utilized for operation of the sensor system rather than heat transfer to the superheat, resulting in a far more stable and efficient refrigeration control.

Abstract: A refrigeration system having a plurality of cooled surfaces, each of which has a thermostatically controlled refrigerant supply valve. The valves are pulse-width modulated, each having the same period and being so controlled so they have staggered openings relative to one another thus providing a more uniform load on the system.

Abstract: A suction valve for an axial piston compressor has a leaf spring fixed at one end, which spring at one end is fixed with a fixed portion between valve plate and cylinder block, at its other end covers over the suction valve opening with a closure portion and has an intermediate portion connecting these portions. The intermediate portion is located substantially outside the cylinder cross-section. A stop for the suction valve leaf spring is arranged in the region of the cylinder wall facing the fixed portion. This produces an optimum filling of the cylinder and thus an improvement in the efficiency of the compressor, as is especially desirable for refrigeration compressors.

Abstract: A hydraulic axial piston machine (1) is disclosed, having a cylinder drum (3) with at least one cylinder (4), in which a piston (5) is arranged to move back and forth, which piston bears by way of a slider shoe (7) against a swash plate (8), wherein a pressure plate (9) is provided which holds the slider shoe (7) in contact with the swash plate (8) and is supported against the cylinder drum (3) by way of a ball-and-socket joint (10) comprising a ball-like body (12) and a counterpart (13). In such an arrangement, one would like to avoid weakening the pressure plate by the ball-and-socket joint. To that end, a part of the ball-and-socket joint (10) is provided with a supporting surface (17) which extends substantially parallel to the surface of the pressure plate (9) and by means of which this element (12) lies in face-to-face contact with the pressure plate (9).

Abstract: A valve is disclosed having a closure member which co-operates with a valve seat and is movable by an actuating device with a driver element, which driver element is guided in a housing. It is desirable for such a valve to operate reliably and have a long service life. For that purpose, a high-temperature thermoplast is arranged between the housing and the driver element.

Abstract: A hydraulic valve with a housing, which is made of a plastic material, and with at least two fluid connections and a valve element arranged movably in the housing. A valve of this kind must on the one hand be able to withstand a sufficient pressure and on the other hand the production of the valve must be inexpensive. For this purpose the housing is surrounded by a metal sheet enclosure having at each fluid connection an opening, which is surrounded by a metal sheet wall projecting from and connected with the metal sheet enclosure.

Abstract: An enclosure for a transmitter, particularly a pressure transmitter, comprising an upper part containing connection terminals and an outer enclosure connected with the upper part. A printed circuit board is mounted in the chamber formed by the upper part and the outer enclosure. To increase the immunity of the pressure transmitter from electrical noise, an inner conducting cylinder is used, the cylinder being fixed by a pressure fitting with the outer enclosure. At the same time stampings in the inner cylinder fix the printed circuit board and create earth connection from the printed circuit board via the inner cylinder to the outer enclosure. Besides improving the noise immunity, the invention simplifies assembly of the transmitter and increases mechanical strength, including resistance towards turning and tilting torques.

Abstract: A refrigerant compressor has a reciprocating piston with a projection extending therefrom is disposed in a cylinder. The cylinder has an end wall with a discharge opening operably closeable by a discharge valve. The projection is disposed on an end face of the piston and extends into the opening of the discharge valve when the piston is in the region of its end position. Extending the projection into the discharge valve enables gas remaining in the region above the piston and in the region of the discharge opening to be displaced out of the discharge valve. The projection has an asymmetrical construction with a circumferential wall has a gradient changing along the circumference of the wall. The discharge valve seat and the flow channel in the region of the discharge valve are operably contoured to prevent turbulent flow from occurring when gas is discharged from the discharge valve.

Abstract: A three-way or multi-way valve is provided, which is built up of a plurality of two-way valves, each of which has a high pressure connection and a low pressure connection which are separated from each other by means of a valve seat with which a closure element co-operates, the two-way valves being arranged to be operated in pairs or in groups by means of a control pressure fluid by way of a control pressure line opening into a pressure chamber, and one of the two-way valves of each group being arranged in a connection between a pressure source and a load, and another two-way valve of the same groups being arranged in a connection between the load and a pressure sink. With a valve of this type, it is desired to obtain improved closing behavior with simple construction. For this purpose, at least one of the connections, especially the high pressure connection, of at least one valve of each group communicates with the control pressure line by way of a throttle channel.