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: The present invention relates to the measuring of phase currents in an inverter, where by pulse width modulation controlled semiconductor switches invert a direct voltage from an intermediate circuit into a three-phase alternating voltage. The phase currents are measured by measuring the intermediate circuit current when an active switch state creates an unambiguous relation between the intermediate circuit current and a phase current. Time shifts in the phase current measuring can be avoided by measuring the value i.sub.d of the intermediate circuit current in two separate settings (u.sub.1, u.sub.1, u.sub.6, u.sub.6) of the same active switch state (u.sub.1, u.sub.6) in a modulation period (T.sub.sw) and by creating a resulting means value of the measured values. The mean values can be related in time to the center of the modulation period, and the third phase current at the same time can be calculated, because the sum of the phase currents is equal to zero.

Abstract: A refrigerant compressor is disclosed, having an electric motor, the stator of which has windings with winding heads and the rotor of which drives a compressor which comprises a compressor lock having an axially projecting bearing part for a rotor shaft, one winding head extending in the direction of the compressor block and electrical insulation being provided between the winding head and the compressor block. With the same overall size, it is desirable to be able to improve the efficiency of such a refrigerant compressor without markedly increasing the effort involved in assembly. To that end, the insulation is formed by a film which is pushed with a substantially centrally arranged opening onto the bearing part.

Abstract: A two-way seat-type valve is provided, having a valve seat which is arranged between a first and a second connection, and having a closure element which co-operates with the valve seat, is arranged in a guide so as to be movable towards the valve seat or away from the valve seat, and which is subjected to a control pressure prevailing in a pressure chamber on the side, remote from the valve seat, of the closure element. A valve of this type should also be able to exhibit good reaction characteristics with water as hydraulic fluid. For this purpose, the closure element is guided seallessly in the guide.

Abstract: A hydraulic piston machine is disclosed, having a piston arranged to move back and forth in a cylinder body. In such a machine it is desirable to be able to achieve a longer service life, even when the hydraulic medium is not suitable for lubricating the bearing faces. For that purpose, at least on its outer face sliding on the cylinder body, the piston has a layer of a friction-reducing plastics material, wherein at the end of the piston there is provided a bearing face of an articulated joint by means of which a slide shoe is connected, articulated to the piston, the layer being continued onto the bearing face.

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: There is disclosed a method and system for improving the user interface between operator and motor controller, in particular a frequency converter. According to the invention, instead of presenting all information on a display at one time, a method of programming the motor controller is suggested, in which the operator is guided through the set up procedure, so that only relevant parameters are displayed on the different views. Another aspect of the invention is a method of programming a motor controller not in terms of parameter and parameter numbers, but in physical, technical and process terms. In this way, a high level mode of programming a motor controller is achieved, because the user interface does not deal with the less interesting motor controller specific parameters, but instead allows the operator to program the unit in terms he uses.

Abstract: A hydraulic control system for work vehicles including a control unit to control the steering wheels of a vehicle via a cylinder and a priority valve which by a first load-sensing system controls the pressure fluid flow to the control unit and to a subsequent proportional valve group. By a second load-sensing system the proportional valve group controls the pressure fluid flow to secondary hydraulic motors or work cylinders to control the work tools of the vehicle. The control system also includes an open-centre valve connection and a fixed displacement pump. The first load-sensing system is connected with a second load-sensing system, whereby drop-off of the pressure fluid flow to the control unit is avoided at simultaneous operation of the latter and of one or several of the proportional valves as is the case with known control systems. Hereby a control system is provided which is particularly agreeable to operate for the driver of the work vehicle.

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: 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: 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 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.