Abstract: A compressor (1) with at least one piston (9) movable in a cylinder (10), a drive shaft (2) and a wobble plate arrangement (4, 5) between piston (9) and drive shaft (2), having an inclined plate (4) with variable inclination angle, and with a spring arrangement (17; 41 to 43), acting on the wobble plate arrangement in the direction of a minimum displacement. Such a compressor should also be able to operate at higher pressures without increasing its size, e.g. to enable the use of CO.sub.2 as refrigerant. For this purpose the spring arrangement (17; 41 to 43) acts on the wobble plate arrangement (4, 5) in the area of the radial edge.

Abstract: A control plate (1) of a hydraulic machine having a core (2) is disclosed, which at least on its upper side (O), lying in operation against a cylinder drum, is covered with a layer of friction-reducing plastics material (3). The plastics material (3) is joined to the core (2) by means of a connecting element (8) which, as a result of interlocking engagement with the plastics material (3) and/or the core (2), takes up tensile forces substantially at right angles to the upper side (O).

Abstract: A valve, which has heat-sensitive parts, has at least one connecting tube to which a pipe is arranged to be soldered using local heating. The connecting tube consists of a material of such low thermal conductivity that the heat-sensitive parts remain below the limit temperature as the heat required for soldering is applied. No cooling measures are therefore needed while the pipe is being joined by soldering.

Abstract: An analysis method is disclosed, in which several samples are passed in succession through a reaction channel 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 described, having axially movable pistons, which at one end bear by means of slider shoes against a slanting plate, and having a pressure plate (10) for holding the slider shoes in contact with the slanting plate. Under certain operating conditions the slider shoes have a tendency to tilt and lift away from the slanting plate at one side. To prevent this, the pressure plate (10) acts only on a part lying, in the radial direction of the slanting plate (7), outside a predetermined region (28).

Abstract: A hydraulic system with a pressure source controllable via a load sensing signal, a pressure sink, at least two working sections, each having a hydraulic consumer and a control valve with a load sensing signal connection and at least one back-pressure valve arranged in a tank pipe between the control valve and the pressure sink. In such a system the pressure required from the pump in the neutral position must be as low as possible. On the other hand, however, oscillations should not occur, when an external force acts on another hydraulic consumer in the neutral position of a control valve. In the neutral position of the control valves the load sensing signal connection is therefore connected with the pressure sink via an auxiliary tank pipe by-passing the back-pressure valve.

Abstract: The invention concerns a control valve with a housing, having a pump connection, a tank connection device, a working connection device and a load pressure connection device, each connected with an opening device in a control surface, and with a slide, arranged movably in the housing and co-operating with the control surface, the slide having grooves and/or channels, so that it connects or separates predetermined opening devices with/from each other. In such a control valve the tightness must be improved. For this purpose an additional auxiliary tank connection device is provided, which is connected with an auxiliary tank opening device in the control surface. The slide has an auxiliary tank pipe or groove, which, in its neutral position, connects the auxiliary tank opening device with the load pressure opening device.

Abstract: A sampling means of a chemical analysis apparatus includes a membrane, which is attached to a membrane carrier, which has an inlet passage to the side of the carrier facing the membrane and a discharge passage going therefrom. The passages conduct the medium to be measured and which medium absorbs ions, molecules or particles which pierce the membrane. In order to provide a sampling means, which has a short reaction time and makes use of small amounts of the medium to be measured and is easy to manufacture, the mouths of the inlet passage and of the discharge passage, which opens to the membrane, are interconnected by means of at least one groove, which is open towards the membrane. The groove is formed in a surface layer, which is attached between the membrane and the membrane carrier or is manufactured on the surface of the membrane carrier. The open side of the groove is closed by the membrane such that the membrane adheres to the surface layer or to the surface of the carrier facing the membrane.

Abstract: A compressor is disclosed, in particular for air-conditioning systems in vehicles, having at least one piston movable in a cylinder, a drive shaft and a wobble plate arrangement between the piston and the drive shaft. To improve the efficiency and to reduce leaks, the wobble plate arrangement comprises a swash plate, on which a wobble plate is rotatably mounted. Between the wobble plate and the piston is arranged a bearing which allows movement of the wobble plate relative to the piston in the circumferential direction.

Abstract: A hydraulic piston machine is disclosed, having a cylinder body, which has at least one cylinder, in which a piston is arranged to move back and forth and bears by way of a slide shoe against a control surface, and having a pressure plate which holds the slide shoe in engagement with the control surface. It is desirable to be able to operate such a machine also with a fluid that has no or only poor lubricating properties. To that end, the pressure plate and/or the control surface is provided with a layer of a friction-reducing plastics material at least in one of the regions with which in operation they rub against other parts.

Abstract: In a valve, in particular an expansion valve for refrigeration systems, at least the housing (2) and all nozzles (3, 4, 5) are deep-drawn parts of stainless steel having a carbon content of less than 0.05%. These parts are joined to one another by soldering. The steel has such a low content of carbon that despite being subjected to the effects of heat during soldering, it is practically insensitive to intercrystalline corrosion. This produces a visually attractive valve that is not harmful to the environment.

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 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.