Abstract: In general, a sealing apparatus for substantially preventing the flow of air through a damper assembly having a plurality of movable vanes includes a first, rigid sealing member having a generally circular cross-section and adapted to be attached to a first edge of a first movable vane. The first edge is movable through a first arc between a damper-open position and a damper-closed position. A second resilient sealing member has a generally rectangular cross-section and is adapted to be attached to a second edge of a second movable vane. The second edge is movable through a second arc between the damper-open and damper-closed positions. The sealing members make substantially line contact one with the other as the edges are moved toward the damper-closed position and are in substantially gas flow-preventing area contact one with the other when the vanes are in the damper-closed position.

Abstract: A control apparatus for repetitively verifying the integrity of a main fuel valve control circuit in a standing pilot burner system includes a probe circuit adapted to receive an electrical signal representative of the presence of a standing pilot flame and a first circuit which coacts with the probe circuit for energizing a first relay in response to the electrical signal. A second circuit is adapted to receive a heat demand signal and coacts with the first circuit for sequentially disabling the probe circuit, de-energizing the first relay, energizing a second relay, re-enabling the probe circuit and re-energizing the first relay to actuate a main fuel valve.

Abstract: In general, an electronic control module includes a module frame adapted for swingable mounting to a rail member. The module includes a plurality of bus conductors constructed and arranged to engage the bus conductors of adjacent modules when mounted. The module also includes a plurality of electrically-conductive pads for engaging a circuit board which is attachable to the module frame. Terminals are included for the connective termination of external wiring. The module is swingably removable from a rail member while yet avoiding movement of a module which may be mounted adjacent thereto. The invention is particularly useful for the construction of electronic digital communication systems used with heating, ventilating and air conditioning equipment.

Abstract: The compressor motor controller of the present invention includes a hot motor detector adapted to be coupled to a plurality of temperature sensors for detecting an overtemperature condition of the compressor motor. The hot motor detector incorporates logic switching means for generating a motor control signal. A self diagnostic sensor is coupled to the hot motor detector for detecting an electrically shorted condition of the temperature sensors while a low voltage detector is coupled to the hot motor detector for sensing a low line voltage condition. Means are provided for protecting the compressor motor against the undesirable effects of short cycle operation while a lubricating oil pressure detector receives signals from a pressure transducer which are representative of oil pressure.

Abstract: The thermostat of the present invention includes a sensor for providing a signal representative of the actual temperature within a space. A microcomputer is coupled to the sensor and intermittently utilizes power at a first level when in an operating state for controllably generating output signals in response to the temperature signal. The microcomputer is adapted to be connected to a battery as a sole power source therefor. An isolating interface device such as an electromagnetic relay is coupled to the microcomputer and is adapted for connection to temperature-affecting equipment such as a heating or cooling system controller. The relay actuates the equipment in response to output signals from the microcomputer. A voltage detection circuit may optionally be provided for signalling a low battery voltage condition.

Abstract: The invention facilitates the reception of bus-transmitted digital signals in the presence of electrical noise and includes a transmitter adapted to be coupled to a two wire communication bus. The transmitter has a controllable transistor for switching one wire of the bus between zero and reference voltages, thereby generating digital output signals. A receiver is coupled to the bus for receiving digital input signals which define a first wave form and are transitory between a first voltage and a second voltage. The receiver includes an R-C circuit for shaping the first wave form to a second wave form and a hysteresis switch for providing a first output condition when the second wave form transcends through a first intermediate voltage in a first transition direction. A second output condition is provided when the second wave form transcends through a second intermediate voltage in a second transition direction.

Abstract: An apparatus for maintaining a relatively moist ambient gas in intimate contact with a humidity sensing element includes a control nozzle for flowing relatively dry pneumatic control gas therethrough. The nozzle is adapted to be modulated for controlling the humidity within a space. A rigid control cone is coupled to the nozzle for defining a cavity therebetween and having a fixed volume. The cone includes a pin member which is movable with respect to the cone for effecting nozzle modulation. A discharge spigot is disposed in fluid flow communication with the cavity, the spigot being arranged for exhausting the pneumatic control gas to a region remote from the humidity sensing element.

Abstract: A low level, microprocessor based direct digital system controller includes power supply means for providing a source of regulated electrical power to the controller. A field programmable processor means transfers selected data base information to and receives status signals from a field interface means, digitally executes control and energy management algorithms respecting those signals in accordance with computer program routines selected from a library of mnemonically identified routines residing in the read only memory (ROM) portion of the processor means. The processor means responsively directs programmed data and digital command signals to the field interface means which periodically updates the data base of the processor means, analyzes and conditions signals received therein from the processor means and from remote data points and selectively controls the data points.

Abstract: The hinge of the present invention comprises an I-shaped support bracket including an elongage body member and a plurality of laterally extending flanges. A panel bracket is adapted for attachment to a generally planar panel member and includes means for pivotably coupling the panel bracket to the flanges along a first pivot axis. A door bracket is provided for attachment to a generally planar door member and includes means for pivotably coupling the door member to the flanges along a second pivot axis. When closed, the supported door member is disposed in a reference plane and in generally normal, edgewise relationship to the panel member. The support bracket, panel bracket and door bracket cooperate during door opening and closing for permitting lateral door movement generally parallel to the reference plane. The panel bracket and the door bracket may optionally be configured to be interchangeable one with the other.

Abstract: A motor-driven rotary actuator includes an electric drive motor adapted to be configured for providing one of a plurality of output torques and power transmission means including a rotatable output shaft. The transmission means is coupled to the drive motor and includes drive elements adapted to be formed of disparate materials selected for transmitting one of the output torques. An electric controller is coupled to the motor for providing rotation positioning control of the actuator output shaft in response to analog command signals.

Abstract: An electronically controlled apparatus for controllably positioning pneumatic actuators includes, in a first embodiment, first means for selectively flowing compressed fluid to the actuator and valve means for selectively exhausting compressed fluid from the actuator. An electronic control panel is adapted to receive digital command signals from a computerized controller and is coupled to the first means and to the valve means for actuation thereof in response to the command signals. Means are included for isolating electrical switching transients from the controller.In a second preferred embodiment, the positioner also includes transducer means for generating a feedback signal representative of the position of the actuator piston assembly. A third preferred embodiment is similar to that of the second embodiment and incorporates a control adapted to receive analog rather than digital command signals. An optional high limit pressure switch may be used with any embodiment.

Abstract: A transducer for generating a feedback signal representative of the position of a movable member includes a signal generating mechanism for providing an electrical feedback signal representative of the position of the movable member. The signal generating mechanism includes a first shaft portion having a first longitudinal centerline and a drive mechanism having a shaft member coupled in driving engagement to the first shaft portion. The drive mechanism is adapted to be cable connected to one of a plurality of movable members having maximum travel spans different one from the other. The shaft member has a shaft longitudinal centerline which is concentric with the first centerline, the centerlines defining a first axis. An alignment mechanism is coupled to the drive mechanism and the signal generating mechanism and permits limited movement of the first axis with respect to a reference axis. The alignment mechanism thereby isolates the signal generating mechanism from misalignment reaction forces.

Abstract: An amplifying pneumatic switch which is responsive to low pressure signals includes a first chamber for receiving an input signal from a first pneumatic pressure source at a first pressure. The first chamber includes a wall formed by a movable, highly resilient diaphragm. A diaphragm plate is disposed generally coextensive with the diaphragm and is responsive to diaphragm movement. A nozzle is coupled to a second source of pneumatic pressure and is sealable for generating a pneumatic output signal at a second pressure. A sealing mechanism including a lever and a plunger coact between the diaphragm and the nozzle for sealing the nozzle in response to the input signal. A spring is provided for biasing the diaphragm plate to a quiescent position in the absence of an input signal.

Abstract: A mechanical draft controller integrated in the draft hood of a furnace and coupled to a flue damper is responsive to the draft in the flue for controlling exhaust stack heat loss and eliminating heated room air loss via the draft hood under normal operating conditions. The pressure-sensitive controller is variably positioned as a face damper on a surface of the draft hood and is coupled to the flue damper by means of mechanical linkage. Increasing pressure in the draft hood caused by a reduction in the draft value due to partial flue blockage, large down draft, etc., displaces the pivoted controller resulting in a corresponding opening of the flue damper to re-establish the desired draft value. Similarly, excessive draft causes the displacement of the controller in an opposite direction resulting in flue damper displacement so as to reduce the draft value and exhaust stack heat loss.

Abstract: An x-ray probe carrier for the inspection of circumferential welds in cylindrical pipes includes a carriage supported on omnidirectional ball transfers for movement along the bottom of a pipe section. A centrally mounted adjustable probe holder is preset to coincide with the centerline of the pipe for single exposure x-ray examination of a full circumferential weld. The probe is maintained centered during travel along the pipe and is automatically recentered after travel through a horizontal bend. The probe holder is easily adjustable for use in a wide range of pipe sizes.

Abstract: An humidistat has an element movable in response to ambient relative humidity operatively connected to a core of a linearly variable differential transformer for moving the core. The core is supported within a body portion of the transformer for minimal friction of movement relative to the body portion. The body portion has a primary winding and two secondary windings. An oscillator excites the primary winding to provide output signals from the secondary windings proportioned to movement of the core in the body portion and, therefore, indicative of the relative humidity sensed by the element.

Abstract: A digital start-stop multiplexing system including a sender which sequentially scans a plurality of monitoring points and generates a train of digital pulses coded to represent information provided at the monitoring points for transmission over a transmission line to a receiver which is responsive to the digital pulse to automatically synchronize itself with the sender, store the data pulses and provide indications of conditions indicated at the monitoring points. The receiver also monitors the transmission line and detects and displays open or short circuit conditions of the transmission line. Coded pulses may also be transmitted from the receiver location to the remote sender over the same transmission line during stop portions of the primary signal.

Abstract: An analog signal comparator receives a variable potential signal at each of two input ports. The signal at each input port is provided to a gate of one programmable unijunction transistor (PUT) and an anode of another PUT to form mirror-image symmetrical connections to the two PUT's. An output signal from either of the PUT's then indicates the lesser of the potentials at a corresponding one of the input terminals. The comparator is preferably intended for use in a closed-loop motor positioning system.

Abstract: A fail-safe timing circuit energizable in response to a starting signal for activating a system, such as a fuel ignition system or an air conditioning system, includes a first switching circuit responsive to the request signal to activate the system to commence its operation tentatively, a time-out circuit responsive to the starting signal for generating a time-out signal after a predetermined time delay interval, a circuit responsive to a system variable such as the establishment of a flame in a fuel ignition system or the sufficient increase in oil pressure of a compressor in an air conditioning system becoming a predetermined condition, such as the flame occurring or the compressor oil pressure achieving a given desired value, for preventing the time-out circuit from generating its time-out signal, and a second switching circuit for causing the first switching circuit to de-activate the system in response to the time-out signal.

Abstract: A pilot fuel ignition system including an ignition circuit for generating sparks for igniting fuel emanating from a pilot burner to establish a pilot flame, a control circuit responsive to the ignition circuit to operate a pilot valve to supply fuel to the pilot burner, and a sampling circuit controlled by the control circuit to maintain the pilot valve operated and to operate a main burner valve to supply fuel to a main burner for ignition by the pilot flame. A flame sensing circuit enabled whenever a pilot flame is established normally disables the ignition circuit, but periodically enables the ignition circuit to test the operability of the ignition circuit. Failure of the ignition circuit to operate results in the disabling of the sampling circuit causing shutoff of the pilot and main burner valves. Also, a warp switch energized whenever the pilot flame is extinguished effects shutoff of the pilot valve interrupting the supply of fuel to the pilot and the main burners.