Abstract: Apparatus for picking-up and analyzing emitted accoustic and ultrasonic signals by means of a piezoelectric pick-up element connected to an amplifier with high input resistance, the output of the amplifier being connected for further evaluation to selective circuits and to an evaluation device. The piezoelectric pick-up element is situated in a casing, said casing being fixed to a hollow body being tested as by a strap encompassing at least partly both the casing and the tested hollow body.

Abstract: Inverted current rectifier with self commutation for smaller and medium output and three-stage commutation in which the disconnection of thyristors of the inverted rectifier and the current commutation in the phases are separated and the accumulated power of capacitors of the inverted rectifier is, without losses, discharged to the current source and thus to the load of the inverted rectifier.

Abstract: A process of pulse duration modulation for improved voltage and frequency efficiency of a multi-phase converter. The sum of the time dependent voltage of a load phase and of an auxiliary time dependent voltage is formed, wherein the auxiliary time dependent voltage is the same for all converter phases. The pulse duration of the output voltage of each converter phase is modulated with said voltage sum.

Abstract: A three phase current inverter has a commutation circuit wherein a blocking voltage is generated which is applied from the anode to the cathode of the main control thyristors. The load current from the then-conductive phase is simultaneously transferred to the commutating or disconnect circuit. A separate accumulation circuit including a capacitor then takes over the load current, the energy stored in the load inductance being transferred to the capacitance in the accumulation circuit. The control thyristor for the next phase is switched to the conductive state, current is transferred from the accumulation circuit to the subsequent output phase and from the load of the first phase to the load of the second phase. The capacitor in the disconnect circuit is smaller than that in the accumulation circuit so that optimum characteristics for both circuits are obtained.

Abstract: Circuit arrangement for inverters with three stage self-commutation suitable for large outputs and for parallel connection of main thyristors and separating reactors.

Abstract: A circuit arrangement for the driving and for independent recuperation braking of a vehicle provided with DC compound traction motors, a DC feeding circuit, and pulse control for obtaining braking with so-called clean recuperation. The series windings of the motors and their armatures are connected to a tetragonal circuit with four terminals, with a pulse converter controlling the armature voltage of the motors.

Abstract: An arrangement for complex diagnosis of internal combustion engines in the course of their operation comprising a control unit, a measuring unit, an operating unit, an evaluation unit and an indication unit, and a transducer for determining parameters such as pressures, vibrations, emitted supersonic signals and temperatures at different positions of the crankshaft and under various engine operating conditions.

Abstract: There is disclosed a liquid cooler for semiconductor power elements, the cooler having an external surface for bearing against the cooled element. The internal space of the cooler is formed so as to generate a whirling motion of the cooling medium supplied thereto.

Abstract: A test circuit for determining when one of a number of source voltages deviates from its set point. Each source voltage has coordinated comparison circuit which compares the voltage with a preset value, and which has a limited range of output voltage. Each comparison circuit has its output connected to a switching circuit. The output of each switching circuit is connected to a short circuit coil of one coupling transformer. The coupling transformer is fed from an auxiliary current source through an auxiliary coil and has as output a pick-up coil connected to an evaluation device.

Abstract: An improved construction for a two or three terminal power semiconductive device provides efficient thermal and electrical conduction between the heat-generating semiconductive wafer and the associated terminal electrodes with the use of a permanent, flowable thin layer of liquid metal therebetween. The liquid metal is carried in annular reservoirs within the outer surfaces of the terminal electrodes confronting the planar surfaces of the wafer, and serve to conduct the heat from the wafer to a hollow heat-dissipating well within the terminal electrodes. The wall of the well is made porous or is otherwise configured or reinforced to effectively increase the surface area thereof to aid in heat dissipation. If desired, an auxiliary seal-bearing groove is disposed concentric with and radially inwardly of the reservoir on at least one of the terminal electrodes, such groove bearing an O-ring or similar seal which bears against the confronting surface of the wafer to confine the flow of the liquid metal layer.

Abstract: A flat surface of a planar power semiconductive element, such as a thyristor or diode, is adjustably urged downwardly against a heat sink in electrical and thermal contact therewith by means of a spring-loaded eccentric element. The spring extends transversely over the opposite surface of the semiconductive element between a pair of anchor members carried by the heat sink. The eccentric is secured to an intermediate portion of the transversely extending spring, and is adapted to rotate in a vertical plane whereby successive portions of the eccentric periphery are urged with different pressures downwardly against the opposed surface of the semiconductive element, either directly or through an insulating spacer element. If desired, a pair of flattened abutment areas may be established on diametrically opposed portions of the eccentric periphery to correspondingly define a two-position stable adjustment of the bearing pressure.

Abstract: A rapid and accurate technique for generating indications representative of the specific resistance of a test sample, such as a silicon disc, is described. A capacitive probe is electrostatically coupled to the sample, and the input terminals of the probe are coupled to the output terminals of a reactive circuit that is excited with a high-frequency current and that includes a capacitive path connected across an input coil to transform the measured loss resistance of the sample (proportional to the specific resistance) to the terminals of the first coil. An auxiliary path including a pair of serially connected compensating inductors is connected between the junction of the capacitors in the capacitive path and a reference terminal of the input coil, with the junction of the compensating coils and the reference terminal forming the output of the reactive circuit.

Abstract: An arrangement including a hydraulic chamber for simultaneously regulating the contact pressure on a plurality of heat sinks associated with planar semiconductor devices to be cooled is described. A corresponding plurality of elongated rods coupled at their outer ends to one surface of each of the heat sinks extend outwardly through aligned holes in a boundary wall of the chamber. A plunger or other suitable device extends into the chamber through a second opening therein to vary the pressure on the compressible medium and thereby to urge the heat sinks against the associated semiconductive elements with a uniform pressure. Facilities are provided for electrically deactivating the semiconductive elements when the pressure within the chamber falls below a predetermined value.

Abstract: An apparatus for testing engine oils and in particular oils to be used in compression ignition engines. The apparatus includes a receptacle in which a sample of the liquid oil to be tested is poured. The receptacle has a cover plate with an opening. A test plate is mounted in the opening of the cover plate and seals the receptacle. A shaft with radial projections is mounted in the receptacle and submerged in the liquid oil to be tested. When the shaft rotates the projections splash oil against the test plate. First temperature sensing means are mounted in the test plate and second temperature sensing means are submerged in the liquid oil. A heating element is mounted over the cover plate. The first temperature sensing means are operatively connected to the heating element via a thermal regulator to thereby maintain the test plate at a preselected temperature. The second temperature sensing means serve to maintain the liquid oil sample at a preselected temperature.

Abstract: A high-power semiconductive device having a conductive liquid for maintaining contact between the active semiconductive element and the associated current supply and feeding facilities is described. A resilient insulating ring disposed in contact with the periphery of the active semiconductive element is contacted on respectively opposite sides by a pair of heat-conductive tubes that serve as the current supply elements of the device. A pair of conductive plates disposed on opposite sides of the semiconductive element are secured to the sides of the heat-conductive tubes to close off a pair of mutually insulated chambers which are bounded on the other side by the terminal areas of the semiconductive element. The conductive liquid is disposed in each of the so-defined chambers to provide thermal and electrical contact between the heat-conductive tubes and the terminal areas of the semiconductive element.

Abstract: A supporting ring for stator vanes in an axial compressor. The supporting ring permits an adjustment of the angular position of the stator vanes. The adjustment is carried out by removing the stator body while the machine is at standstill. The supporting ring is provided with recesses which are defined by an elastic wall which also defines the bores in which the stator vanes are mounted. Clamping bolts are provided in the elastic wall and by tightening these clamping bolts the stator vanes are held in a predetermined position.

Abstract: A semi-conductor cooling system formed of a container having a wall portion made of soft yieldable material which is adapted to contact the surface of a semi-conductor device. A porous member is disposed within the container adjacent the inner surface of the yieldable wall. A liquid medium partially fills the remainder of the chamber immersing at least a portion of the porous member. The latent heat of the semi-conductor device is dissipated via the porous member in a closed evaporator-condensing cycle.

Abstract: A semi-conductor cooling system formed of a container having a wall portion made of soft yieldable material which is adapted to contact the surface of a semi-conductor device. A porous member is disposed within the container adjacent the inner surface of the yieldable wall. A liquid medium partially fills the remainder of the chamber immersing at least a portion of the porous member. The latent heat of the semiconductor device is dissipated via the porous member in a closed evaporator-condensing cycle.

Abstract: Piezoelectric pick-up device for measuring internal overpressure of hollow bodies such as cylindrical pipes. The device has similar parts which present a cavity therebetween with a circular cross section with a circular groove. Within the groove there is disposed an insert composed of four parts, said insert encompassing the hollow body and transmits the deformations of the hollow body due to overpressure therewithin to piezoelectric plates. The four parts of the insert are advantageously made of steel.