Abstract: A unique method of operating a refrigeration system for rapidly pulling down a refrigerated container temperature includes the use and algorithm for operating several system components. The refrigeration system is preferably provided with a suction modulation valve, a compressor unloader and an economizer circuit. By utilizing each of these components in combination with one another, and at various stages during the pull down capacity and energy efficiency of the refrigeration system are optimized, while maintaining the system operation within preset limits.

Abstract: A control for a refrigeration system serviced by a special pulse width modulated compressor coupled to a condenser and evaporator. The system can be of the distributed type wherein the condenser and compressor may be coupled to service a group of adjacent refrigeration cases, wherein each case would have its own evaporator. A controller is coupled to a load sensor for producing a variable duty cycle control signal in which the duty cycle is a function of demand for cooling. Moreover, fuzzy logic techniques may be utilized in order to provide self adaptive tuning control for the system.

Abstract: A thermal zone demand controlled dual cascade arranged heat pump system and system controller for building spaces, having first and second heat pumps and having an air circulation system for circulating air to and from said thermal zones and including a conditioned air chamber having first and second heat exchange refrigerant coils being connected in refrigerant circulating relation respectively with the heat pumps. A plurality of thermal zone blowers conduct conditioned air, heated or cooled, from the conditioned air chamber to respective thermal zones of the building space. Electronic controller circuitry of the system is coupled for thermal demand control of the heat pumps and the thermal zone blowers for operation of the first heat pump to accommodate a predetermined range of thermal load and for operation of the second heat pump along with the first heat pump to accommodate a greater thermal load.

Abstract: In a positive displacement compressor having a plurality of banks, operation can be multi-staged or single staged. Single stage operation can be of a single bank or plural banks in parallel. Switchover between modes of operation is under the control of a microprocessor responsive to sensed inputs. During pulldown under ambient or condenser entering air temperatures of 100.degree. F., or more, suction modulation is used to limit the suction pressure thereby permitting a switchover to two-stage operation and the use of an economizer.

Abstract: In a positive displacement compressor having a plurality of banks, operation can be multi-staged or single staged. Single stage operation can be of a single bank or plural banks in parallel. Switch-over between modes of operation is under the control of a microprocessor responsive to sensed inputs.

Abstract: Two compressors are connected in tandem for an air conditioning system. A control board that includes a microcontroller controls the operation of the system in response to the energization of first and second stage terminals of a thermostat. The system includes anti-short cycling and eliminating operation of crankcase heaters during a time period following the shutting off of the compressors.

Abstract: System and process are disclosed for the hierarchial control of a plurality of discrete chiller units each having individual dedicated controls. The system and process imposes limits on the amount of compression that can be demanded by the individual dedicated controls. These limits are selectively changed in response to whether a level of chilling has been collectively achieved. The selective changing of these limits is premised on examinations of each individual chiller unit including the recent history of any changes in compression by the unit.

Abstract: A twinning controller or control circuit for use in an HVAC system is coupled between a system thermostat and at least two HVAC units coupled to a common duct. The HVAC units are heating, cooling or heating and cooling appliances such as heating furnaces, air conditioners, fans, other forced air systems, or other devices for heating and/or cooling an environment. The twinning controller is capable of operating in a single-stage mode (single mode) or a double-stage mode (dual mode). When operating in the double-stage mode, the twinning controller alternately operates the first HVAC unit and the second HVAC unit in order to extend the operating life of the HVAC units. The twinning controller includes a microcomputer which receives inputs from the system thermostat and provides outputs to the first and second HVAC units in order to efficiently control the temperature in an environment such as a living space.

Abstract: Multi-purpose indoor units and multi-purpose outdoor units are parallel-connected with each other by refrigerant pipes, and an operating capacity is obtained on the basis of the sum of the demanded capacities of the indoor units and on the basis of the compressor type and maximum capacity of the outdoor units using a control apparatus.

Abstract: A control for a multiple chiller refrigeration system whereby a chiller can be stopped at a predetermined load in order that the remaining building load can be picked up by the remaining running chillers without exceeding set load capacities of the running chillers.

Abstract: A method and control system for operating a chiller system having a lead compressor and a lag compressor in which the load on the compressors is balanced by limiting the % KW demand on the lag compressor from exceeding the 90 KW of the lead compressor while forcing the lag compressor to supply chilled water at a temperature lower than the lead compressor chilled water.

Abstract: A heat exchanger includes a rotary compressor having two compression pumps and a motor for driving the compressor pumps, a condenser connected to the rotary compressor, a regulator connected to the condenser and with an evaporator connected to the regulator. An electric power is supplied from an inverter circuit to the motor of the rotary compressor. The output frequency of the inverter circuit is controlled by a frequency controlling device according to a heat load of a heat exchange circuit subjected. The rotary compressor is operated according to a parallel operation pattern in which the two compression pumps are actuated or a single operation pattern in which a single compression pump is actuated. Either one of the two operation patterns is selected by a selecting device according to the operational condition of the heat exchanger. The switching between the single operation and the parallel operation is performed by a switching device according to the output signal of the selecting device.

Abstract: A control device for energizing and de-energizing temperature changing devices having a primary control unit and a secondary control unit is provided. The primary control unit includes means for sensing an external temperature and generating a signal (Ps) having a value proportional to the external temperature, means for generating a set point signal (Psp), representing one end of a predetermined primary temperature range, and means for generating a differential signal (Pd), representing the difference between signal Psp and the other end of the predetermined primary temperature range are included. Additionally, the primary unit includes a primary switch for connecting power to at least one temperature changing device which is opened and closed in response to combinations of signals Ps, Psp and Pd.

Abstract: A refrigerating cycle apparatus has, in a sealed casing, a compressor including first and second compressor means driven simultaneously. A refrigerating cycle circuit is constituted by connecting this compressor, a condenser, a pressure-reducing device, and an evaporator. Counterflow checking means is provided on the suction side of the first compressor means, for checking the counterflow of the refrigerant from the first compressor means to the evaporator. Switching means is provided on the discharge side of the second compressor means.

Abstract: Methods and apparatus for controlling the load temperature of a transport refrigeration system to a selected set point temperature by operating modes which include a high capacity cooling mode and a lower capacity cooling mode. The rate of change of the load temperature is monitored by time and temperature integration when the lower capacity cooling mode is entered, to insure that the lower capacity cooling mode has adequate capacity to reduce the load temperature to set point within an acceptable period of time. If the set point temperature is not reached within a period of time which is a function of time, load temperature relative to set point, and the rate of change of load temperature relative to set point, a signal is provided which forces the system to the higher capacity cooling mode until the set point temperature is reached.

Abstract: A control apparatus for an air conditioning system has an outdoor unit with a compressor, a condenser and a plurality of motorized valves installed to a plurality of branch pipings. A plurality of indoor units having, a plurality of indoor thermoswitches, a microcomputer, and a drive circuit for driving the motorized valves according to the output from the microcomputer are also provided for the control apparatus. The microcomputer counts the number of indoor units required for operation by receiving the output from the indoor thermoswitch. The microcomputer also controls the opening of the motorized valves by predetermined opening steps, according to the result of the counting and with reference to an opening table. The opening table relates the number of indoor units required for operation with the opening of each of the motorized valves. The control apparatus thus permits an optimum distribution of refrigerant to the indoor units to be set quickly.

Abstract: A cooling system for an electronic apparatus which cools the electronic apparatus using a plurality of cooling fans and controls the rotational speed of the cooling fans in accordance with the temperature of apparatus to be cooled or the temperature of the inlet air or the air to be exhausted. Operation of the electronic apparatus may be continued with high reliability even when one or more fans fail by using simplified circuitry which causes other normal cooling fans to operate at full speed.

Abstract: A method of operating a transport refrigeration system having a six cylinder compressor and a prime mover operable at a selected one of low and high speeds, to control the temperature of a served space by cooling and hot gas heating modes. Below a set point temperature 100, system heating capacity is controlled at the low compressor speed by the step 127 of unloading compressor cylinders and the step 129 of reloading compressor cylinders. A temperature rise of the served space above a set point temperature 106 controls cooling capacity by a combination of alternative steps 135, 137, 139, 141, and 143 which may or may not change the number of loaded compressor cylinders, and may or may not change compressor speed, based upon two predetermined trigger events which relate to what the temperature of the served space does relative to time 136 and 142, a set point temperature 106, and a temperature 108 above set point which is normally associated with a change in compressor speed.

Abstract: A multistage space thermostat control system for controlling a refrigeration heat pump and a furnace controls the heat pump from a first stage of a space thermostat and a furnace from a second stage with anticipation circuit means associated with said thermostat control system which is changed in effectiveness depending upon the operation to reduce temperature swings in the space.

Abstract: The invention provides a control system for a set up including a plurality of boilers, in which each boiler is associated with a control valve which permits or prevents flow through the boiler between common flow and return mains and in which each control valve is connected with a corresponding temperature sensor, whereby the control valves are temperature switched. This compares to conventional practice in multiple boilers set-ups where the said valves are time/delay switched.

Abstract: Apparatus and method for controlling compressor operation in conjunction with sensing the lowest temperature operating evaporator coil, or area serviced thereby, of a commonly-piped cooling system. A thermoelectric sensor voltage output is compared with a set-point voltage by an integrator, the output of which is applied to control the pressure for the system.

Abstract: A controlled refrigeration system includes a plurality of refrigerant compressors fed from a common suction manifold (line). Each compressor is associated with a respective controller. The individual controllers are set to effect the cutting in of its associated compressor at different levels of input voltage from a pressure transducer using digital techniques. The individual controllers each produce respective digital cut-in, cut-out, down-time delay and power-up delay signals. Respective logic circuitry is provided within each controller for producing control outputs which effect the energization and deenergization of the individual controllers. The compressors are turned on and off in sequence as the demand for compression respectively increases and decreases. The power-up delay period differs for each controller so that no more than one is energized at a given time when the system comes on line after a power failure or extended period of shut down.

Abstract: In one exemplar embodiment, method and apparatus for controlling capcity of a multiple-stage cooling system is disclosed which utilizes means for establishing a single predetermined cooling stage "cut-in" pressure and a single predetermined cooling stage "cut-out" pressure, means for determining that the "cut-in" or "cut-out" pressures have been reached in the system, a delay means for introducing a selected minimum time delay after determining that the refrigerant fluid pressure has either reached the established "cut-in" or "cut-out" pressures, and control means for controlling the turning on or off of the next cooling stage after the time delay has elapsed.

Abstract: A capacity control device for a variable displacement compressor in a refrigerating or air conditioning system is disclosed. The capacity control device controls the operation of a variable displacement device having two variable displacement valves for changing the capacity of the compressor as a function of the required refrigerating capacity of the air conditioning system. The capacity control device determines whether the compressor should operate at a high, medium or low capacity. If the required refrigerating capacity is smaller than the current capacity of the compressor, the capacity control device actuates the variable displacement device to enable the compressor to operate at a lower capacity. If the required refrigerating capacity is larger than the current capacity of the compressor, the capacity control device actuates the variable displacement device to enable the compressor to operate at a larger capacity.

Abstract: Apparatus for capacity selecting compressor energization and deenergization in a commonly piped, multiple compressor system comprising largely compressor of unequal capacity wherein the minimum number of such compressors are cycled on/off together and wherein equal capacity compressors in the system are alternately selected to even the wear therebetween.

Abstract: An air-conditioner for an automobile is disclosed which is provided with a compressor adapted to be directly connected to the engine, the compressor being provided with two coaxial compressing cylinders each having a different displacement, whereby the cylinder having the smaller displacement is adapted to be always operated to carry out the dehumidification, while the cylinder having the larger displacement is adapted to be operated only when it is desired to air-condition the compartment by a change in its operation rate through the actuation of such as a slide valve.

Abstract: A multiple chiller control system includes a temperature controller TC, a data base and optimizer DBO, and a plurality of driven-servo loops DSL1, DSL2, . . . DSLn. The temperature controller and the data base and optimizer monitor various parameters of the chilled water system. At periodic intervals, the system determines and stores the current values of these parameters. From this data, and from data determined from operator-selected signals supplied to the temperature controller, the temperature controller determines if a change in total operating capacity is required. If this determination is affirmative, the temperature contoller supplies a request for a system capacity adjustment to the data base and optimizer, which then proceeds to select the chillers to be operated and to adjust the capacity of the chillers so selected.

Abstract: The disclosed temperature control system for an air conditioner includes a sensor for sensing an actual air temperature and a comparator for determining the temperature difference between the sensed actual air temperature and a set air temperature after their conversion to digital voltages. The temperature difference is stored in a memory and is also applied to a calculator where a rate of change in temperature per unit time is calculated from the temperature difference thus formed and from that temperature which had occurred just before a predetermined time stored in the memory. A control unit responds to both the temperature difference and the rate of change in temperature per unit time to increase or decrease the number of compressors put into operation with respect to the number of the compressors operated at the just preceeding interval of time.

Abstract: A system for meeting building air conditioning load conditions by optimally selecting a combination of chillers having dissimilar efficiency characteristics, the system having a load sensor for sensing building load a refrigerant head sensor for sensing refrigerant head of the chillers, and a controller connected to the load sensor and to the refrigerant head sensor for sorting the chillers according to their efficiency characteristics data with the chiller having a minimum kw/ton versus capacity point being ranked first and for selecting a combination of the chillers which will require a minimum energy input to meet building load conditions.

Abstract: An air conditioner includes a plurality of refrigerant compressors, a plurality of ventilating fans and a cooling/warming water pump which is controlled by both a memory and a contact-less control unit in accordance with an outdoor temperature and a refrigerant temperature which are sensed by associated temperature sensors. Alternatively, the control unit may be connected to both protective devices disposed on the fans, the compressors, the pump, etc. and further connected to a digital indicator which indicates the operating status of the air conditioner.

Abstract: An electronically controlled programmable wall thermostat provides better control of comfort temperature and permits improved energy-saving temperature setback at selected intervals of the day or night in multistage heating and cooling systems and is particularly useful in achieving improved energy savings for systems having heat pump means in the main temperature conditioning stage of the system. The thermostat includes clock means, temperature sensing means, means for displaying desired parameters of time and temperature, data entry and storage means for programming the thermostat to maintain desired temperatures during selected time intervals, and a processing means with a memory incorporating a permanently stored program instruction sequence which responds to signals from the temperature sensing means for controlling the heating and cooling systems in accordance with the time-temperature sequence programmed into the thermostat by the user.

Abstract: An air conditioning economizer control method and apparatus for integrating the operation of the economizer with an air conditioning system is disclosed. An economizer position control arrangement is further disclosed incorporating a rotor locking circuit for maintaining the damper in position against a bias applied by mechanical means such as a spring. A multiple position indicator or multiple temperature sensor is utilized to modulate the position of the damper utilizing the motor for opening the damper, a spring for returning the damper and a rotor locking circuit for maintaining the damper in position. Multiple temperature sensors are also disclosed for making effective use of outdoor air when cooling through economizer operation is available. Staged cooling loads relative to outdoor ambient temperatures are utilized to select the appropriate mode of operation.

Abstract: A multistage thermostat means that is adapted for use with equipment such as a heat pump and auxiliary heat and which effects efficient operation upon a temperature setup after a nigh setback function by introducing an exponential change in the apparent control setpoint. The sensitivity of the signal processing channel of the system is altered to maintain stability. The system further contains a power-up reset function that also alters the signal processing channel for rapid reestablishment of normal control.

Abstract: A multiple-compressor refrigeration system for use in commercial refrigeration applications includes a plurality of compressors of unequal refrigeration capacity connected in a refrigeration circuit that includes a condenser and a plurality of associated evaporators and expansion devices in remotely located refrigerated enclosures. A system controller is connected to a pressure responsive transducer that measures the suction pressure of the system and compares the so-measured suction pressure to a desired suction pressure and selects one of a plurality of 2.sup.n available compressor operating states in accordance with the measured difference. The system advantageously increases overall system efficiency by providing increments or decrements of compressor capacity that are more precisely matched to system load changes as compared to prior multiple-compressor systems.

Abstract: A method of controlling heating and cooling sources utilizes a computer or an electronic thermostat to control a plurality of heating or cooling resources for regulating indoor temperature within a narrow temperature range. The method maintains a temperature within the control range by activating a required number of heating or cooling sources and proportionally controlling one of the sources within the control range. An additional heat source is activated each time the indoor temperature falls below a preset "add heat" temperature, and a heat source is deactivated each time the indoor temperature passes a preset "delete Heat" temperature. Similarly, when the method is operating in the cooling mode, an additional cooling source is activated when the indoor temperature passes an "add cooling" temperature, and an additional cooling source is deactivated each time the indoor temperature passes a "delete cooling" temperature.

Abstract: A solid-state control for a variable air volume (VAV) temperature conditioning system adapted to control a plurality of refrigerant cooling stages, and in particular, to modulate an outdoor air economizer. The control includes both an outdoor ambient air and a discharge air temperature sensor. Further included are means for selectively modulating the economizer either in response to the deviation of the discharge air temperature from a setpoint or in response to the discharge air temperature, depending upon the relative magnitudes of the outdoor and discharge air temperature, and upon one or more stages of cooling being energized.

Abstract: A lockout control system locks out the lag load upon occurrence of a predetermined condition in a dual load system set up in a lead-lag configuration. The lockout control system utilizes a lead-lag memory circuit for insuring that only the lag load is locked out when the lockout condition exists irrespective of which load is lead and which load is lag.

Abstract: A dual capacity air-conditioning/heating system including an evaporator, a blower, a compressor and compressor motor, the compressor motor having a two-speed mode of operation. The compressor motor speeds are changed by changing the shunt field current of the motor to achieve a significant reduction of energy consumption in the low-speed mode of operation. The blower motor has a two-speed mode of operation by changing the series armature resistance thereof.

Abstract: A temperature control system utilizing a plurality of heating or cooling devices to maintain the temperature at a desired level, minimizing rapid multi-stage cycling by using dual deadband zones.

Abstract: Apparatus and method for controlling a temperature conditioning system in which a plurality of stages of temperature conditioning apparatus may be selectively energized to meet a temperature conditioning demand in a comfort zone into which the flow of temperature conditioned air is varied in response to temperature therein. Control means are operative to determine the differential temperature of the return air and the supply air and to energize and de-energize stages of temperature conditioning in response thereto. Means are provided to measure the outdoor ambient temperature, thereby enabling the control means to determine the heating capacity of an ambient air source heat pump relative to the outdoor ambient air temperature, and to energize and de-energize heating stages as appropriate, to meet heating demand.

Abstract: Apparatus for rotating a fluid impeller of a centrifugal or axial flow fan, at multiple speeds. A fan is provided with a first and a second electric motor for drivingly rotating a fluid impeller at relatively fast and slow speeds, respectively. The rotor of the first motor directly drives the fluid impeller; the second motor is connected to the impeller shaft of the fan through a belt drive, with pulleys sized to reduce the impeller's rotational speed relative to that of the second motor.Only one of the motors is provided with a start winding. Control means selectively energize the first and second motors, and are operative to energize the one motor long enough to bring the other motor up to operating speed.

Abstract: A method of controlling energy usage of a multi-state heat pump system in which the system includes a preprogrammed microprocessor-based controller which places and maintains the system in the most energy efficient mode of operation consistent with achieving a desired room temperature level within a reasonable period of time. The controller responds to actual room temperature and a user-inserted temperature setting to place the heat pump system into an operating state indicated by a predetermined set of operating state criteria which establishes the required operating state and the timing of state changes. Changing to higher (less energy efficient) operating states is enabled only when periodic checks of the rate of change of room temperature indicate the desired temperature will not be achieved in a selected time period.

Abstract: A thermostat adapted to regulate the operation of a heating system and a cooling system in response to the temperature in a space conditioned by the systems. The thermostat has a pair of means selectively movable to respective ones of adjusted positions and adapted for sensing the temperature of the space within a preselected temperature range, respectively. A pair of sets of at least three switching means are associated with the sensing means and are operable for controlling the operation of the heating system and the cooling system, respectively.

Abstract: An optimization system for switching between plural parallel connected chillers in a refrigeration system is disclosed which system establishes optimized changeover criteria based upon the design refrigerant head for the chillers, the minimum refrigerant head for the chillers, the capacity of the chillers at design head and the capacity of the chillers at minimum head, and which system, using these criteria, calculates optimized switchover capacity as a function of the present actual refrigerant head. The system then compares the optimized switchover capacity to the present building load and, if the capacity is insufficient to meet the building load, an additional chiller is switched in and, if the optimized switchover capacity is greater than the building load and more than one chiller is operating, one of the chillers is disconnected.

Abstract: A refrigeration system including multiple parallel compressors for maintaining evaporator suction pressures within preselected ranges, said compressors being sequentially and cyclically operative through control switch means responsive to preselected upper and lower refrigerant suction pressures, a fluidic time delay system for operating the pressure responsive switch means comprising restrictor means interposed between the common suction header for the compressors and the pressure responsive switch means therefor to restrict refrigerant fluid flow to the pressure switches upon increases in suction header pressure, and unidirectional flow means for providing unrestricted reduction of the pressure acting on the switch means upon relative decreases in suction header pressure.