Abstract: Thermoelectric heat pumps using parallel flow, crossflow, or counter-flow of the input and output fluid streams have been designed and built, but performance has been insensitive to flow arrangement due to the use of one-piece, essentially isothermal heat exchangers on the heated and cooled thermoelectric junctions. Thus, none of these designs have capitalized on the sensitivity of the thermoelectric coefficient of performance to the junctions temperature differences and the smaller temperature differences possible with the counter-flow arrangement. In the improved design, the thermoelectric heat pump is broken down into discrete sections which heat or cool the input fluid in stages. The system thus operates as several discrete heat pumps each doing only a small portion of the heat pumping without sacrificing the desired final outlet temperature. Thus, the junction temperature differentials for each thermoelectric unit in the system is less than that with conventional one-piece heat sink designs.

Abstract: A plural switch matrix is connected as a direct ac-to-dc converter between an induction generator and an a-c load. The generator provides three-phase output energy which is switched and controlled by the converter, to supply a controlled three-phase quasi-square wave (QSW) voltage to a load. The converter switching provides periodic shorts across the generator terminals, translating some of the mechanical input energy into electrical energy to sustain the generator field. The converter is regulated by gating signals from a combinational logic circuit.

Abstract: A control system used to change the gear ratio in a gear set regulated by a change-gear signal from a control unit is disclosed. A transducer provides an output torque signal which is compared to other signals for initiating the gear change.In another arrangement, an automatic transmission changes a gear ratio when engine torque is transferred from one member to another member of a three member planetary gear set. This transfer is accomplished through friction elements engaged by hydraulic pressure. A closed loop electrical circuit is completed between a transducer, which provides an electrical signal related to the output torque of the transmission, and a control valve, to vary the control valve pressure. A circuit for computing reaction torque is coupled between the transducer and a logic control circuit, which provides logic command signals for controlling operation of components in the closed loop circuit.

Abstract: A longitudinal joint is supported adjacent the paving form by a plurality of hangers, each of which includes an attaching portion for affixing to the paving form, thus obviating the need for chair supports or other known devices for supporting a longitudinal joint. Each of these hangers includes a support-holder portion extending at an acute angle with respect to the paving form, defining an angle for receiving a portion on the longitudinal joint. This both supports the joint vertically and restrains it against horizontal movement away from the paving form. In addition the longitudinal joint is modified so that the normal apertures for receiving the extension of the tie bar, instead of being formed in a flat surface of the joint, are provided in a plane substantially perpendicular to the length or axis of the joint.

Abstract: A bipolar inverter has power switches connected such that the inverter can be energized with a d-c voltage of either polarity, or by an a-c voltage. Each power switch of the bipolar arrangement can include inverse-parallel connected thyristors, an individual triac, or a diode bridge with a thyristor connected across the bridge. A commutation circuit for a bipolar inverter is described. A single power switch also has utility as a power transfer component in addition to its use with an additional power switch in one leg of a bipolar inverter. Different circuit implementations for the bipolar inverter are described, including use with an induction generator, a heterodyne frequency converter, and a power regeneration system.

Abstract: A three-phase rectifier circuit is connected to provide a d-c output voltage as a function of the three-phase energy passed to the rectifier circuit. This energy is reduced in amplitude over a voltage divider circuit and passed through an optically-coupled detector circuit to provide a control signal indicating the presence of energy on all phase conductors of the supply line. If a fuse blows in one line, or if the power on that line is interrupted for any reason, the ripple content of the rectified voltage increases. This is sensed by a detector circuit to energize an alarm and/or interrupt the main power bus to the load.

Abstract: A background discussion of induction machine equivalent circuits, including operation as an induction generator, is provided. Selective shorting of the machine terminals is described, to convert at least some of the mechanical input energy into electrical field energy for the machine. Systems are described for accomplishing the selective shorting with a single-phase machine, including sensing of the zero-crossing of the output voltage to insure that the shorting is effected at the appropriate time to replenish the field. The shorting time duration can be varied as a function of load. A three-phase shorting circuit is also described.

Abstract: A background discussion of induction machine equivalent circuits, including operation as an induction generator, is provided. Selective shorting of the machine terminals is described, to convert at least some of the mechanical input energy into electrical field energy for the machine. Systems are described for accomplishing the selective shorting with a single-phase machine, including sensing of the zero-crossing of the output voltage to insure that the shorting is effected at the appropriate time to replenish the field. The shorting time duration can be varied as a function of load. A three-phase shorting circuit is then described.

Abstract: A measuring system indicates the tension in a belt which transfers power between driving and driven pulleys. A support member has a pair of idler rollers journalled in the proper positions to pinch the belt, thus providing a force on each idler roller. A strain gauge or mechanical spring-and-indicator is used to display the difference in forces at the two idler rollers, which difference is a function of the tension in the belt.

Abstract: The disclosed voltage generating system includes certain known components, such as an induction machine driven as a generator, the output connections of which are coupled to the normal load connections of a switching system, which can be a bridge-type inverter. The system switching frequency f.sub.1 is regulated by firing pulses from a logic circuit in turn controlled by an oscillator. By controlling operation of the inverter switches with respect to the synchronous frequency (mechanical rotational speed) of the machine, a d-c voltage is provided on the normal inverter bus conductors.In the disclosed system the conventional inverter switches (such as SCR's) are replaced by true two-way power switches, capable of passing current in either direction. In addition the firing signals provided by the usual logic circuit and applied to these power switches are modified so that the switching occurs as a function not only of the first oscillator frequency f.sub.

Abstract: A bipolar inverter circuit comprises power switches for providing alternating energy to the load notwithstanding the polarity of the energizing voltage. Each leg of the bipolar inverter or power conversion circuit includes a pair of power switches, each having a diode bridge with a thyristor coupled across the normal bridge output terminals to complete a path for current flow through the power switch when the thyristor is gated on. Each leg also has a complementary commutating circuit for turning off one of the thyristors whenever the other is gated on.

Abstract: An induction machine is driven to operate as a generator, and has its electrical output conductors coupled to a switching system, which can be an inverter circuit. An oscillator and logic circuit are connected to regulate the switching of the power switches, such as thyristors, in the inverter circuit which operates as a switching system. The thyristors in the switching system are regulated to switch at a frequency sufficiently below the synchronous frequency of the induction machine to enable the machine to build up and operate as a generator. A modulator is connected to the oscillator to vary the oscillator frequency, and thus change the switching frequency of the switching system, above and below a reference level to provide a corresponding a-c output voltage, with a d-c average level, on the d-c bus conductors of the inverter circuit which operates as the switching system.

Abstract: A static switch including main and auxiliary SCR's has a commutating capacitor coupled between the common connections of these main and auxiliary SCR's. An independent external charging circuit is provided and connected to complete a charging path for the commutating capacitor which is isolated by at least one diode from the main d-c bus. This enables the commutating capacitor to charge to a level above that of the d-c bus voltage and maintain effective commutation.

Abstract: A tape transport of the type with a resilient capstan abutting the tape packs on the supply and takeup reels includes a bias unit coupled between the supply reel support and takeup reel support to urge both reels against the capstan with the same force. A drag torque is applied to the supply reel during operation to maintain the appropriate tape tensions in the system.

Abstract: A simulated alcoholic breath sample is provided by circulating a known volume of a gas such as air or non-alcoholic breath over the outer surface of a container filled with ethyl alcohol and maintained at a given temperature, the container having a wall permeable by ethyl alcohol at a known permeation rate. Circulation of the volume of gas is continued until the gas has the desired alcohol concentration.

Abstract: An automotive control system utilizes a pulse-generating circuit driven as a function of wheel angular velocity to produce electrical signals related to vehicle wheel rotation. The signals are shaped, filtered and passed to associated equipment, such as regulated braking circuits, to perform the regulating function. The frequency doubling circuit is provided to accommodate different sensing systems which produce fewer output signals for a given angular displacement of a vehicle wheel.