Abstract: The invention relates to a control circuit for a brushless self-starting D.C. motor of the type which has a permanent magnet rotor and a stator coil, a magnetic field-dependent component subjected to the rotor field to determine the rotary position, and a controllable electronic servo-element lying in series with the stator coil at the D.C. source, the servo-element controlling the flux through the stator coil in dependence on the rotary position of the rotor, the magnetic field-dependent parameter changes of the magnetic field-dependent component being convertible to a control signal for the servo-element. The control circuit is characterized by including an oscillator with an LC resonance circuit of which the inductance is formed by the magnetic field-dependent component in the form of a sensing coil (10) with a core. The circuit includes a modulator for modulating the oscillation of the oscillator in response to the induction brought about in the sensing coil by the torot field.

Abstract: The invention relates to a piston assembly for compressor and the method of making the assembly. A piston body is molded with spaced apart downwardly open grooves formed with concave semicylindrically shaped summits and parallel side walls. The summits and sidewalls are formed with pimples. A connecting rod pin having a connecting rod attached thereto is press fitted into the grooves. The pimples may serve as weld pimples by being softened by a welding current. The pimples on the sidewalls may alternatively be mechanically swaged to press inwardly against the rod to hold it in its installed position.

Abstract: The invention relates to a method and apparatus for controlling a three-phase inverted rectifier. In this method each half wave is divided into six intervals with the third and fourth intervals forming a first zone with a constant voltage level, the second and fifth intervals forming a second zone with impulses of varying width, and the first and sixth intervals forming a third zone with impulses of varying width narrower than the impulses in the second zone. The narrower and wider impulses are treated similarly with regard to their number and have a constant width ratio as the result of a factor X. The center spacings of the narrower and wider impulses are equal. The number of impulses in each of the zones two and three is n. When n is 1.5, X should be about 0.78.

Abstract: The invention relates to a spring brake assembly of the compressed air type for truck tractor types of vehicles. The brake actuators of the assembly each includes a heavy coil type emergency spring which is held in a compressed state on the back side of a diaphragm by compressed air applied to the front side of the diaphragm during operation of the vehicle. The emergency spring expands to actuate a brake setting push rod when the compressed air is vented from the front side of the diaphragm and this occurs when the vehicle engine is turned off or when there is an accidental loss of compressed air from the brake unit. The emergency spring is housed in a chamber and, due to the movement of the diaphragm, atmospheric air is continually being drawn into and expelled from that chamber. As the brake actuators are mounted on the rear axle of the vehicle, they are in low positions relative to the roadway and the air drawn into the emergency spring chambers thereof is laddened with salt and water.

Abstract: The invention relates to a method and apparatus for controlling an inverted rectifier having a constant DC supply voltage and adjustable frequency and amplitude of the fundamental oscillation of the output voltage. The rectifier is for an AC motor and the phase voltage is at least partly formed by width-modulated pulses and the voltage-time area of the pulse series is increased to eliminate an inadequate pulse spacing. Switching elements in the rectifier require a certain switching time and care must thus be taken to ensure that certain minimum pulse widths or pulse spacings must be observed to avoid short circuiting in the rectifier. Also to be avoided is pulse bridging which leads to a sudden increase in the voltage-time area and thus to a leap in the amplitude of the fundamental oscillation of the output voltage. The effects of this, e.g. in the magnetization of a connected motor, are undesirable.

Abstract: The invention relates to a temperature control system for refrigeration unit. In this system a capillary tube extends between the condenser and the evaporator and a chamber upstream from at least a section of the capillary tube contains a PTC resistor. The PTC resistor is supplied with current in response to a thermostatic sensing of a predetermined low temperature in the room or compartment which contains the evaporator. In response thereto the PTC resistor generates enough heat to produce a vapor plug which throttles of stops the flow of refrigerant in the capillary section but not enough heat to cause coking of the refrigerant oil which would permanently plug the capillary tube. The downstream capillary section is so dimensioned that it is permeable to liquid refrigerant but is substantially impermeable to the refrigerant vapor generated in the chamber.

Abstract: This invention relates to a snap action type of switch in which a generally G-shaped sheet metal strip has a fixed terminus and a movable terminus forming an inwardly and upwardly extending arm which is pivotally mounted in a knife bearing. The midportion of the strip extends between fixed contacts and has a contact thereon which alternately engages the fixed contacts. An actuator is movable transversely of the strip and engages the arm of the strip to move the movable contact in the opposite direction relative to the movement of the actuator.

Abstract: The invention relates to a control circuit for a servomotor of the type having a piston displaceable to selectable positions in one direction by an expansible substance heatable by an electric heating element and in the other direction by a return spring. The circuit includes a pulsating power supply and a control switch and a thermostatic unit for generating a temperature responsive control voltage. A potentiometer for generating voltages corresponding to different positions of the piston is operably connected to the piston. A comparator for comparing the control voltage with the potentiometer voltage generates a go-no go signal which is relayed to the heating element control switch. Upper and lower limit switches are associated with the selectable positions of the piston. The limit switches selectively override the potentiometer to effect operation of the heating element control switch. Light emitting diodes are provided which give visual indications of the heating and cooling cycles.

Abstract: The invention relates to an electric switch assembly of the type operated by a thermostatic bellows, for use on refrigerators. The operating bellows is part of a system having a liquid/vapor filling and the movement of the bellows operates a microswitch. A hinged arm which operates the microswitch is biased in a switch closing direction by the bellows and in a switch opening direction by a spring system which includes a main spring and a differential spring in series. The force displacement line of the spring system approximates the force displacement line of the bellows and has two segments with different slopes. The two segments are formed by arresting the movement of the differential spring to make it ineffective at an intermediate point in the displacement of the bellows. The first segment with a lesser slope represents the action of both springs in series while the other segment, of greater slope, represents only the main spring.

Abstract: The invention relates to a cut-off valve assembly for an oil burner assembly. The cut-off valve is of the type which is spring biased and rapidly opens and closes above and below a predetermined pump pressure. The rapid closing is to prevent fuel oil from dripping from the nozzle. The valve assembly has an expansible chamber formed with a diaphragm. The chamber has inlet and outlet ports with a valve seat formed on the outlet port. A spring biased adjustment element has a disk shaped portion below the diaphragm which carries a closure member for the outlet port. The face of the closure member is displaceable relative to the disk shaped portion and is of a larger diameter than the diameter of the valve seat for the outlet port.

Abstract: The invention relates to a control unit for an inverted rectifier of the type having a constant DC voltage supply and a frequency settable by a frequency control signal. The main feature of the control unit relative to the invention hereof is the monitoring of the critical pulse spacings of the pulse generator output without the use of time-dependent elements. The control unit includes a voltage controlled oscillator for generating a triangular wave form controlled by a frequency control voltage. A variable width pulse generator is fed by the triangular wave form and is controlled by a pulse width control voltage. The control unit includes an analog computer for generating internally thereof a function which corresponds to the spacing of the pulses of the pulse generator. The computer includes an amplifier having a noninverting input for receiving a control signal which corresponds to the amplitude of the triangular wave form.

Abstract: The invention relates to a hydraulic regulator of a type which may be operated by electromagnetic switching valves. The assembly includes a piston and cylinder arrangement with position setting chambers at opposite ends thereof of larger diameter than the servo piston. Movable abutment elements in the chambers of larger diameter than the servo piston are biased by centering springs. There are parallel circuit branches in which the end chambers are disposed and switching valves are in these branches. The actuating of one of the valves to block its branch lower the pressure in the end chamber in that branch causing the piston to move towards the blocked branch so as to move away from the biasing force of the opposite spring biased element and engage the biasing force of the adjacent spring biased element. When the other switching valve is actuated to block its branch to stop the piston in a desired position, the fluid pressure in the end chambers is equal.

Abstract: The invention relates to a hydraulic regulator of a type which may be operated by electromagnetic switching valves. The assembly includes a piston and cylinder arrangement with position setting chambers at opposite ends thereof of larger diameter than the servo piston. Movable abutment elements in the chambers of larger diameter than the servo piston are biased by centering springs. There are parallel circuit branches in which the end chambers are disposed and switching valves are in these branches. The actuating of one of the valves to block its branch raises the pressure in the end chamber in that branch causing the piston to move in the other direction so as to move away from the biasing force of one spring biased element and engage the biasing force of the other spring biased element. When the other switching valve is actuated to block its branch to stop the piston in a desired position, the fluid pressure in the end chambers is equal.

Abstract: The invention relates to a hydraulic control unit for a servomotor of the type used for vehicle steering systems. The unit has a control circuit with a power operated pump and a hand operated metering motor and an operating circuit with a power operated pump. The two circuits intersect upstream from the servomotor. A pressure comparison, throttling and proportioning valve is disposed between the outlets of the two pumps of the control and operating circuits. The proportioning valve is controlled by a differential pressure applied by the pumps and a spring which supplements the operating pump pressure. In the normal operating mode the proportioning valve allows a minor fractional flow of the pressurized fluid generated by the control pump to flow through the valve to the operating circuit.

Abstract: The invention relates to a brushless self-starting D.C. motor assembly of the type having a rotor with a permanent magnet providing a rotor field, a stator, and one or more stator windings. A D.C. source is provided along with electrically controllable power transistor switch means between said source and each of the windings. A position sensing coil element is mounted adjacent the rotor and has a core which is saturatable by the rotor field at a predetermined position of the rotor to provide a control signal. A control unit is disposed between the means and each of the switches for receiving the control signal and actuating each of the switches in turn in response thereto. The core is preferably ferrite and preferably a permanent magnet.

Abstract: The invention relates to a system for measuring or controlling the thermal comfort in spaces used by living beings. In operation an output signal is produced which indicates whether or how much the actual thermal conditions in the space differ from comfort conditions and this output signal may be used to control the comfort conditions in the space. The sensing means takes into account the same conditions as does a living being with respect to convection heat, radiation heat and the heat produced by metabolism. The last mentioned heat might be set in accordance to the activity level of the living being. The surface temperature of the sensing means is compared with a comfort temperature set by a second setting means. If the first setting means is set to a higher heat supply, the second setting means is simultaneously set to a lower comfort temperature and vice versa.

Abstract: An electromagnetic valve assembly of the type having a tube for guiding the plunger armature which tube also supports the surrounding coil unit. A U-shaped yoke surrounds the coil and a housing is provided. The tube, which is attached to a valve casing, has an annular recess at the opposite end for receiving the slotted ring of a ring and nut pair which uses the tube as an abutment for biasing the yoke and the housing towards the valve casing. A lock ring is between the slotted ring and the yoke which has a first lug in a slot of the slotted member and a second lug in a recess in the housing to prevent relative rotation between the slotted ring and the housing.

Abstract: The invention relates to a hydraulic control apparatus of the type used in vehicle steering systems. In all such systems there is a reversible type hydraulic motor connected to the steering linkage. The motor has complementary expansible chambers. With the use of control means pressurized fluid is selectively delivered to one chamber which is caused to expand concomitantly with the collapsing of the other chamber from which fluid is returned to a sump. There is provided in the control and power circuit throttle valves having respective opening positions which correspond to the pressure difference on both sides of the valves. Between the passages which extend to the two control circuit throttle valves is a pressure comparator which is operable to vary the pressure upstream of the power circuit throttle valve in proportion to the pressure upstream of the control circuit throttle valve.

Abstract: The invention relates to a single-phase motor assembly which includes in the circuit means thereof a starting winding in series with a starting resistor having NTC and PTC characteristics. The NTC and PTC characteristics are sequentially related. The NTC characteristic has an ohmic range which extends from a value above to a value below a predetermined critical ohm value at which a current sufficient for starting the motor flow in the starting winding. The PTC characteristic has an ohm range which extends from a value below to a value above the critical ohmic value referred to.

Abstract: The invention relates to a hydraulic control valve assembly, or a plurality of control valve assemblies, for controlling one or more consumer units such as hydraulic motors. Each valve assembly has conventional supply and exhaust ports for selectively and alternately pressuring and exhausting two ports to which a consumer unit is connected. Each valve assembly has pressure sensing control ports which sense pressure in the consumer unit ports. Conduit means connected to the control ports include a pressure differential regulator which shunts the supply pressure and which reacts to pressure supplied to the consumer unit to control the regulator. In a preferred embodiment comprising a plurality of control valve assemblies and associated consumers and a common pressure differential regulator, the individual sensing conduits of all control units are connectable at one end to the return conduit in the neutral position and are combined at the other end to form a collecting sensing conduit.