Abstract: A method for defrosting a refrigeration system makes provision for partial defrosting of the cooling surface to be carried out at relatively short intervals, and for full defrosting to be carried out at longer intervals. To that end an associated control unit has four timers which determine the switching on and switching off times of the defrosting processes. In this manner the interval between successive full defrostings can be considerably increased.

Abstract: A hydraulic control arrangement is disclosed having a directional valve, a metering pump unit which has two metering pumps which are connected hydraulically in parallel and are operable mechanically in parallel, and a shut-off valve in a hydraulic connection between the two metering pumps, a pump connection and a tank connection which are connected to the metering pump unit by way of the directional valve, and also two working connections which are connected to the directional valve, a control inlet of the shut-off valve being connected to the pump connection. Such a control unit should be constructed to be user-friendly, especially for emergency operation. For that purpose, a safety valve arrangement is arranged between the control inlet of the shut-off valve and the directional valve.

Abstract: A water-operated hydraulic control valve is disclosed, having a throttling device which comprises a throttling element (20) which is in the form of a piston which cooperates with a substantially hollow-cylindrical counter-element (8).In order also to be able to operate such a control valve with water, that is, a non-lubricating fluid of low boiling point, the throttling element (20) projects with one end (29) into the counter-element (8). Distributed in the circumferential direction, several apertures (30) are provided in the throttling element (20) or in the counter-element (8), forming a flow path through the overlap region between throttling element (20) and counter-element (8), and distributed in the circumferential direction there is provided an arrangement of pressure pockets (33), which arrangement is in fluid connection with the apertures (30) and is arranged at least partially in the overlap region.

Abstract: A refrigerant compressor arrangement is disclosed, having a compressor which is arranged in a housing and which has a suction connection, the housing being provided with a suction connector which is joined to the suction connection by way of a suction channel. In such an arrangement, it is desirable to increase the opportunity of the compressor to move, that is, to reduce noise, without at the same time having to accept a deterioration in efficiency. To that end, at its housing end the suction channel is in the form of a telescope tube which is capable of being telescoped into the suction connector.

Abstract: A method for operating a motor/compressor combination, especially for hermetically-encapsulated small refrigerating machines, comprises a compressor having a periodically operating displacement element, which is driven by a brushless motor (3). To start the motor, it is subjected to asynchronous and then synchronous commutation of its stator windings (7,8,9). For starting, the rotor is turned by asynchronous commutation from any given rest position to a starting position that facilitates running-up and is then started from that starting position. A motor/compressor combination for carrying out that method has a control arrangement (10) which, in asynchronous commutation, enables the current-application patterns to succeed one another in such a manner that the rotor is turned from the rest position to the starting position and is started therefrom. In that manner, the motor/compressor combination can be started reliably even in the event of unfavourable conditions.

Abstract: A pressure-applying arrangement in a hydraulic axial piston machine is disclosed, having a pressure plate (7) and a piston (9) that is axially displaceable in a cylinder body (3), is biased by a spring (10) and acts against the pressure plate (7). It should also be possible to use such a pressure-applying arrangement when the axial piston machine is operated with a hydraulic fluid that has no or only very little lubricating property, for example, water. For that purpose, the piston (9) is formed from a high-strength thermoplastics material.

Abstract: A method is disclosed for calibrating an analysis system having a membrane, the outside of which is in contact with a medium to be analyzed, in order to detect a concentration of a species there, and a corresponding analysis system. In this connection it is desirable to be able to perform a calibration in situ. In this calibration, a first fluid of a predetermined first concentration of the species is conveyed along the inside of the membrane, at least a second fluid of a predetermined second concentration which differs from the first concentration is likewise conveyed past the inside of the membrane and the concentrations of the two fluids after passing the inside of the membrane are recorded. From these concentrations, parameters for a correlation between the concentration on the outside of the membrane and a measurement signal are ascertained.

Abstract: A piston with a slide shoe for a hydraulic piston engine, where the slide shoe comprises a ball socket, and where the piston is arranged with a corresponding ball head, whereby these are joined in a ball-and-socket joint, and where at least partially the ball head is constituted of a spherical surface of a friction reducing material moulded onto and retained in relation the piston. As a consequence of the subsequent shrinking of the moulded-on, friction reducing material, a possibility is obtained of good fixation of the ball head on the piston, while at the same time a gap can be created between the ball socket and the ball head.

Abstract: A control arrangement for the superheat temperature of at least one evaporator of a refrigeration system having a refrigerant circulation, in which at least one compressor, a condenser, an electronically controlled expansion valve and the evaporator are arranged in series, contains a measuring device connected to the evaporator, which device produces a measurement signal Tu that is a measure of the superheat temperature of the refrigerant in the evaporator, a comparator to which the measurement signal Tu and a desired superheat temperature signal Tu.sub.s are arranged to be supplied, and a PID controller arranged between the comparator and the expansion valve. For rapid compensation of changes in the superheat temperature, a control signal S proportional to the evaporation temperature T.sub.o of the refrigerant is arranged to be supplied additionally to the PID controller.

Abstract: An analysis method is disclosed, in which several samples are passed in succession through a reaction channel (16) to a detector (17), and at least one reagent is introduced into the reaction channel (16) for reaction with the samples. An apparatus for implementing the method is also disclosed. Using the method and the apparatus, it is intended to specify an analysis method more capable of coping with different flow characteristics of the samples in fluid form. For that purpose, each sample and its associated reagent is introduced in a controlled manner into the reaction channel so that they form a block, along the length of which the local volume ratio between sample and reagent, averaged over a segment of predetermined length, is substantially constant, the length of the segment being substantially shorter than half the length of the block.

Abstract: A hydraulic axial piston machine is disclosed, having a cylinder drum, which has at least one cylinder in which a piston is arranged to move back and forth, which piston bears by way of a slide shoe against a swash plate, wherein the cylinder drum and the swash plate are rotatable relative to one another, and a pressure plate, which holds the slide shoe in contact with the swash plate, is joined, articulated, to the cylinder drum by way of a ball-and-socket joint having a convexly spherical bearing surface. It is desirable for manufacture of such a machine to be simplified. To that end, the bearing surface is formed by a friction-reducing plastics material.

Abstract: A method for achieving a specific temperature behavior of adjusting elements, operating in dependence on temperature, of valves or thermostatic apparatus is disclosed, and also an adjusting element, operating in dependence on temperature, of valves or thermostatic apparatus. Such adjusting elements work in many cases by means of pressure from a pressure chamber, which is provided with a liquid-gas filling. This filling is in many cases toxic or environmentally harmful, in order to achieve satisfactorily the desired temperature behavior. In order to be able to use also non-toxic and environmentally harmless substances, the pressure chamber is filled with a zeotropic mixture of at least two substances. The ratio of component substances is set in dependence on the desired temperature behavior.

Abstract: An add-in device for a hydraulic control arrangement provides a function unit (24) to be arranged between successive modules, which function unit takes the connection between the pump channels of the preceding and the subsequent module by way of at least one function slide valve (117, 217) which is arranged to be displaced into several positions. In its positions this function slide valve initiates different functions, by which fluid under pressure is arranged to be admitted to the subsequent control module in at least two different amounts and/or in at least two different levels of pressure. In this manner operation of the subsequent control modules can be better matched to the particular operating conditions that obtain.

Abstract: An analysis method and an analysis apparatus are disclosed, in which several fluid samples are passed in succession through a reaction channel to a detector, and at least one reagent is introduced into the reaction channel for reaction with the samples. It is intended thereby to be able to reduce the consumption of chemicals. For that purpose, successive samples are introduced adjoining one another into the reaction channel.

Abstract: A hydraulic machine with two displacement elements (2,3) rotatably movable relative to one another, namely, a gearwheel (2) and an annular gear (3) of which the number of teeth is one more than the number of teeth (N) of the gearwheel (2), in which machine the tooth form of a least one displacement element (2,3) is defined at least over sections by a trochoid-type curve T=f (RC, E, RT) as the function of a reference circle radius RC, an eccentricity E and a generating circle radius RT. In a machine of that kind, it is desirable for the efficiency and the running behaviour to be improved and for wear to be reduced. To that end, of the parameters (RC, E, RT) determining the function f, at least one parameter varies in the circumferential direction periodically with the period of a tooth pitch (Z).

Abstract: A hydraulic control valve for controlling flow between a pump, a hydraulic device, and a vessel containing hydraulic fluid. The control valve has an elongated valve slide which is slidably mounted in an elongated valve housing. The valve has three positions, a central neutral position, a float position axially offset in one direction from the neutral position and a constant pressure position axially offset in the opposite direction from the neutral position. In the neutral position, flow of hydraulic fluid to the hydraulic device is inhibited. In the float position, connection is such that a raised device, such as a hydraulically operated bucket, is lowered slowly by gravity until it rests on the ground or another object. In the constant pressure position, the valve connects pump pressure to the load sensing circuit to facilitate, for example, shaking of a bucket of a piece of earth moving equipment.

Abstract: A piston/slide shoe arrangement of a hydraulic piston machine is disclosed having a slide shoe in connection with a piston (4), with a friction reducing plastics material there between, wherein the plastics material, forming channel, extend into a through opening in the slide shoe in a direction towards a sliding contact surface of the slide shoe. The sliding contact surface in operation lies against a swash plate. The slide shoe and the plastics material are provided outside the through-opening with at least one connecting element which takes up the shear forces between the slide shoe and the plastics material.

Abstract: A piston with a slide shoe is described for a hydraulic piston engine, where the piston is designed with a ball socket, and where the slide shoe is provided with a corresponding ball head, whereby these are connected in a ball-and-socket joint, and where the ball head of the slide shoe is designed as a unit moulded into the ball socket in friction reducing material so that the ball head is captured in the ball socket. Hereby an improved fixation of the moulded-on all head on the slide shoe is achieved.

Abstract: A hydraulic axial piston motor (1) is disclosed, having a cylinder drum (4) which is connected, so that it is non-movable axially, to a shaft (3) and so that they rotate together, and which has at least one cylinder (5), for each cylinder a piston (6) arranged in the cylinder, which piston bears at its end projecting from the cylinder drum (4) against a swash plate (8) via the intermediary of a slider shoe (7), a pressure-applying arrangement (9) for holding at least one slider shoe (7) against the swash plate and a control plate (12) with control kidneys. It is desirable for such a motor to be reliably operable even when the shaft is provided with axial play. Leakages in particular are to be avoided. For that purpose, the pressure-applying device (9) is mounted so as to e axially movable relative to the cylinder drum (4).

Abstract: A steering system for vehicles or ships is provided, with a steering handwheel and a steering element with no mechanical linkage line therebetween, with a steering handwheel sensor device, a steering element sensor device and a control arrangement which, in dependence on the output signals of the sensor devices, operates an electromechanical transducer, on the output side of which the steering element is arranged. It is desirable to increase the reliability of such a steering system For that purpose, the control arrangement comprises at least two independent control units, and a fault-monitoring device is provided which precludes a defective control unit from influencing the steering element.