Abstract: A refrigerated display case with multiple air curtains and a refrigerating apparatus for refrigerating circulating air. The refrigerating apparatus includes a compressor, a condenser and two evaporators. The suction sides of both evaporators are connected with one another by a first passage line which includes first and second compression device with check valves in series, this line being connected to the compressor through valve devices. The discharge sides of both evaporators are also connected with one another by a second passage line which includes a pair of check valves, this second line being connected to the compressor through valve devices, respectively. The first and second passage lines are connected with one another and connected to the condenser through a valve device whereby both evaporators are parallel or serial connected with one another due to operation of the valve devices to accomplish the refrigerating mode or refrigerating and defrosting mode of the refrigerating means.

Abstract: Apparatus and a method for determining the appropriate time-to-initiate a defrost cycle in conjunction with a refrigeration circuit having a heat exchanger upon which frost may accumulate. The elapsed time period from a previous defrost cycle is used to adjust the time between defrost cycles such that the time period between defrost cycles is varied as a funtion of the length of the previous defrost cycle.

Abstract: Described herein is a refrigeration defrost cycle monitoring and bypass circuit which monitors the condition of the defrost terminator switch. More specifically, the circuit monitors whether the defrost terminator switch is stuck in either the open or the closed position. This is accomplished using timers to determine the period of time of the defrost cycle and the period of time the terminator switch is open. If either of these times exceed preset values, the defrost terminator switch function is eliminated from the circuit and the control it normally performs is substituted by predetermined times. This occurs by providing a resettable ground to the defrost relay so that it can sense the need to defrost and initiate a defrost cycle. After a defrost cycle is initiated, a user selectable timer ends the defrost cycle after the selected time.

Abstract: Disclosed are apparatus and methods for controlling the defrosting of the outdoor heat exchange coil of a heat pump. In general, the disclosed apparatus and methods use the differencee between the outdoor heat exchanger and the outdoor ambient temperature to determine when to initiate a defrosting operation. Only a single sensor is employed, this single sensor being positioned at least proximate the outdoor heat exchanger such that the sensor responds to ambient temperature when the heat pump is first started and the heat exchanger is free of frost, and such that the sensnor becomes surrounded with frost as frost builds up on the heat exchanger during operation. At the beginning of a run the sensor is employed to read the ambient temperature, which is memorized. As frost builds, the sensor begins to reflect the temperature of the heat exchanger as the sensor becomes increasingly insulated by the frost from the surrounding air.

Abstract: A control circuit for a refrigerator in which the compressor is operated in a pre-cool cycle prior to automatic defrost and in a rapid cooling mode. The control circuit defrosts immediately following rapid cooling when a defrost signal is produced during rapid cooling.

Abstract: A refrigerated display cabinet with multiple air curtains has refrigerating apparatus for refrigerating circulating air. The refrigerating apparatus comprises a compressor, a condenser and two evaporators. The suction sides of both evaporators are connected with one another by a first passage line which includes first and second decompression devices with check valves in series, this line being communicated with the compressor through valve devices. The discharge sides of both evaporators are also connected with one another by a second passage line which includes a pair of check valves, this second line being connected to the compressor through valve devices, respectively. The first and second passage lines are connected with one another and connected to the condenser through a valve device whereby the flow path of the refrigerant can be selectively controlled by operation of the valve devices.

Abstract: A control system for controlling a heating system having a heat pump and a source of supplemental heat. The control system monitors the defrost cycling of the heat pump, and when the heat pump is in its defrost cycle for more than a predetermined portion of a heating cycle, the heat pump will be shut down until the outdoor ambient temperature has risen by a predetermined amount or a given interval of time has elapsed. The heat pump is also shut down if the outside ambient temperature falls below a certain level and is automatically reenabled is the outside ambient exceeds a second level. The system results in more efficient operation of the heat pump/supplemental heat system by disabling the heat pump when weather conditions do not favor efficient heat pump operation.

Abstract: An electronic de-icing thermostat adapted to be connected to an air-cooling apparatus, such as an air conditioner, to control its state of operation. The thermostat includes means for generating a digital electrical signal representative of a desired temperature setpoint, means for measuring the ambient temperature of the thermostat and means for generating control signals for deenergizing the compressor in the air-cooling apparatus for a first preselected period of time whenever the compressor is determined to have run continuously for a second preselected period of time in order to inhibit the accumulation of ice on the cooling element of the air-cooling apparatus. The device preferably includes means for adaptively adjusting the length of the second and/or first preselected periods of time as a function of the change in the rate of change of the ambient temperature measured during the operation of the air-cooling apparatus.

Abstract: Apparatus and method for detecting a failure in an automatic defrost system for a refrigerator. A current sensor means monitors the current supplied to the defrost heater and generates an "on" signal when current is sensed in the defrost heater circuit. A microprocessor determines the "off" time, that is the time between successive "on" signals, and compares this time to a predetermined reference time longer than the normal "off" time. A user discernible signal is generated upon detection of an "off" time greater than the reference time, signifying to the user that the defrost system is not operating properly, and corrective action may be necessary.

Abstract: A control system provides slow and fast defrost cycles for a heat pump by providing an auxiliary manual switch to select different cams of a timing means for cycle operation. Selective ones of the cam switches are connected in parallel to permit two different defrost time cycles utilizing four cams rotating at the same speed.

Abstract: The invention relates to an ice-cream machine for family use with removable whisking vessel, of the type comprising its own refrigerating unit formed by a compressor, a condenser, a lamination valve or a capillary and an evaporator in conditions of thermal exchange with the vessel container. In order to allow for the removal of the vessel when the ice-cream is ready, the refrigerating circuit, between said compressor and condenser, has a duct controlled by a solenoid valve, which opens between said lamination valve or capillary and said evaporator, in order to send at the end of the ice-cream formation, the hot gas outflowing from said compressor directly into said evaporator.

Abstract: A refrigeration system having compressor, condenser, surge receiver and multiple evaporator means, and high side control means including gas defrost means for selectively defrosting the evaporator means with saturated refrigerant gas, a surge control valve for the surge receiver means, and other means for operating the surge control valve in response to differential high side pressures, liquid levels in the receiver means and/or gas defrost operations to regulate refrigerant pressures within the surge receiver means.

Abstract: A microcomputer based monitor and display system for a refrigerator in which visual indicia are provided to indicate to the user the degree of door usage on a rolling average time basis. Threshold time limits are established to correspond to heavy, normal and light usage. The actual door-open time is sensed and accumulated in successive time segments. The rolling average door open time over a predetermined number of time segments is calculated at the end of each time segment and the appropriate lamp is lit depending on how the calculated average door-open time compares to the established threshold values.

Abstract: A defrosting apparatus for removing frost deposited on a cooler of a refrigerator or an air conditioner employs a defrosting heater exhibiting a positive temperature coefficient of resistance which changes sharply at a specific temperature. A specific rate of change of the heater current of the defrosting heater is detected, and on the basis of the detected current change rate, stopping or starting of current supply to the defrosting heater is controlled. The defrosting heater is an organic type heater or an inorganic ceramic type heater possessing the function of self-temperature control.

Abstract: A proximity sensor is mounted on a remote controlled moveable base and is used for detecting a layer of frost of a specified thickness when it accumulates on the subfreezing surface of a refrigeration system. The sensor is positioned at a distance from the subfreezing surface which is greater than the specified thickness of the frost layer which is to be detected. At periodic intervals the moveable base is driven by remote control to move the sensor closer to the subfreezing surface by an amount sufficient for the sensor to make contact with the frost layer when it has accumulated to the specified thickness to be detected.

Abstract: An outdoor coil defrost control system for a reverse cycle refrigeration system comprising outdoor air temperature sensing means, means for producing an output signal indicative of the operation of the refrigeration compression means, and a special controller means having operative connections to the temperature sensing means and compression sensing means and comprising in part (a) a special variable frequency oscillator having an input indicative of the outdoor air temperature and an output signal the frequency of which varies as a non-linear function of the magnitude of the outdoor air temperature, (b) a counter means having an input connected to receive the output signal of the variable frequency oscillator, and (c) means for placing said refrigeration system into an outdoor coil defrost mode of operation upon the counter means counting a preselected number of counts or pulses.

Abstract: A defrost control system is provided for initiating one or more (defrost) timing cycles each at a preselected different time and for terminating the cycles at the end of their respective predetermined (defrost) periods. The unit generally includes a solid-state, microprocessor based, programmable twenty-four hour timer, and a display panel having an electrooptical digital time display and two sets of defrost status/program indicators. The two sets of defrost indicators are separately or concurrently activated to visually present a display indicative of a plurality of program and operating status events, for example, the occurrence of an automatic or manual defrost initiation.

Abstract: A control and method for defrosting the outdoor heat exchanger of an air source heat pump. A defrost cycle is initiated when ice and frost have accumulated on the outdoor heat exchanger sufficiently such that, as a function of the indoor temperature of a comfort zone, the maximum permissible heat transfer degradation at which the efficiency and reliability of the temperature conditioning system are optimized, has occurred. Heat transfer degradation is determined from the outdoor ambient air temperature and the temperature of either the outdoor heat exchanger, or the compressor suction line. If the temperature of the outdoor heat exchanger or the suction line is less than a predetermined value, a deferred defrost cycle is initiated wherein the defrost cycle starts after a fixed time interval has elapsed.

Abstract: A defrost control system is provided for initiating one or more (defrost) timing cycles each at a different time and for terminating the cycles at the end of their respective predetermined (defrost) periods. The unit generally includes a solid-state, microprocessor based, programmable twenty-four hour timer, and a display panel. The system also includes a proportional defrost module which measures the absolute humidity of the atmosphere and adjusts the defrost initiate time(s) in accordance therewith.

Abstract: The time between constant speed defrost cycles is shortened by monitoring the opening and closing of a door of a cooling unit. The control system for doing so includes cam means rotating at a constant speed and electrical switches responsive thereto, a ratchet with missing teeth coupled to the cam means, a pawl engaging the door and the ratchet.

Abstract: A defrost system for refrigerating apparatus having a refrigerating mode and a defrosting mode including an evaporator and an electric resistance heater in heat transfer relationship with the evaporator. There is provided a timer to actuate a normally open defrost initiation switch to energize the heater periodically and initiate a defrosting mode. A defrost terminating thermostat switch is in the heater circuit and will open at a predetermined elevated temperature to deenergize the heater and close at a lower temperature. A voltage sensor across the normally open defrost initiation switch senses periodically and provides a signal when voltage in the heater circuit is interrupted. The multiple voltage sensor signals are stored in a memory bank over a predetermined period of time and when the voltage is interrupted for the predetermined period of time, an alarm is actuated to indicate failure of the defrost system.

Abstract: A refrigerator including a compressor, an evaporator and a condenser with a temperature control to energize and de-energize the compressor. There is an electrical defrost heater for periodically warming the evaporator to defrost temperatures which is energized and de-energized by an electrical motor-driven defrost control timer having a predetermined period of run time between initiation of each successive defrost cycle. The defrost control timer is energized to run only when the compressor is energized and the defrost control timer is delayed in running for a period of time each time the compressor is energized.

Abstract: An improved system for control of defrost in a refrigeration system of the type wherein one or more evaporators are defrosted by hot gas from the compressor while one or more evaporators remain in refrigeration operation. Prior to operating diverting valves to establish defrosting gas flow in an evaporator, a liquid line valve is closed and the system is pumped down to a predetermined amount of refrigerant charge in the defrost loop. In a preferred embodiment, this is accomplished by first opening the liquid line valve to flood the system, then closing it for a predetermined time interval to pump down to the predetermined amount of charge prior to operating the diverting valves.

Abstract: The resonant frequency of an electroacoustic transducer controls the frequency of an oscillating circuit while the transducer vibratile element remains unobstructed. An extended small area portion of the vibratile element is mounted at a fixed distance from the sub-freezing surface of a freezer compartment on which a specified layer of frost is to be detected. When the frost layer builds up to the specified thickness it makes contact with the extended vibratile tip portion of the vibratile element and inhibits the vibration of the vibratile element thus causing the oscillator circuit to stop oscillating. The detected change in the circuit condition is used to initiate the defrost cycle.

Abstract: A heat pump having successive defrosting operations initiated, controlled and timed by a microprocessor-based controller. The time intervals between defrost cycles are periodically varied as needed, dependent on outdoor temperature and certain operating conditions of the heat pump system. Initially the microprocessor is programmed to select and establish a minimum outdoor temperature-related defrost lockout time interval which may then be automatically extended during the lockout period by amounts of time during which, simultaneously, the outdoor coil is above a predetermined coil temperature level and the heat pump compressor is not running. The minimum defrost lockout interval is periodically revised and established, within certain limits, at a value which is dependent on outdoor temperature. An optional feature allows different time vs. temperature lockout time interval functions to be established for different geographical areas having marked differences in average cold weather climatic conditions.

Abstract: A fail-safe electronically controlled defrost system is provided for use in a frost-free refrigerator suitable for home use. The defrost cycle, in the interests of power conservation, is made subject to plural input electronic control in a circuit in which the intrinsic reliability of the defrost system is specifically designed to revert to a non-power conservation mode in the event of failure of the electronics. Compressor time, door openings and user (vacation mode) settings are typical inputs for control of the period between defrosts.

Abstract: A refrigerator includes a compressor, an evaporator fan, a condensor fan and a defrost heater which are controlled by a defrost control system. The control senses the number and duration of freezer and fresh food compartment openings, the duration of the previous defrost operation, and the total accumulated compressor run time since the previous defrosting operation. A stored count is decremented by weighting functions which are adaptably varied in accordance with the number and duration of compartment door openings and the duration of the previous defrosting operation. When the stored count is decremented to zero, the defrosting operation may be initiated, unless inhibited. The defrosting operation is inhibited if the total accumulated compressor run time is less than a predetermined amount. The control is reset to a point just short of a defrosting operation if a power outage occurs.

Abstract: A refrigeration system employing ambient air defrost and a method of operating such a system. The refrigeration system includes a cabinet having an opening in one of its walls, for enabling access to products in the interior of the cabinet. Extending along the walls of the cabinet are an inner, primary air conduit and an outer, secondary air conduit. The primary air conduit contains a plurality of fans for circulating the air along the conduit and a mechanism for refrigerating air passing through the conduit during a refrigeration cycle. The air circulated through the primary conduit forms a closed primary air band. A plurality of second fans are arranged within the secondary air conduit and during a refrigeration cycle circulate air through the conduit, thereby establishing a closed secondary air band during the refrigeration cycle. When the system is to be defrosted, the refrigeration mechanism is deactivated so that the air passing along the primary air conduit is not refrigerated.

Abstract: A refrigerated display cabinet of the open top or open front type having a conduit extending around a storage and display space in the cabinet between an inlet and an outlet, refrigerated coils located in the conduit, air circulating fans for propelling air through the conduit over and/or around and/or through the refrigeration coils in a first direction during a refrigeration cycle, and in a second substantially opposite direction, during a defrost cycle, whereby during a defrost cycle ambient air is drawn into the conduit through the outlet and is passed around and/or through the refrigeration coils to defrost same, a supplemental defroster located in the conduit upstream of the refrigeration coils in the direction of air flow through the conduit in the defrost cycle; and, a sensing and control mechanism coupled with the supplemental defroster for sensing defrost conditions during the defrost cycle and for energizing the supplemental defroster means upon the detection of an abnormal defrost condition to the

Abstract: A system wherein the pulses from a pulse source or the pulses divided or doubled in frequency are selected depending upon environmental conditions, and the number of selected pulses is counted so that an electronic counter generates the defrosting instruction.

Abstract: An automatic defrost system in which the actual defrost time of an evaporator coil, for example, is the controlling parameter for establishing a defrost cycle. The system automatically adjusts itself so that a predetermined amount of frost builds up in the frost accumulating period.

Abstract: Apparatus and method for storing material at and below a permissible upper temperature below the freezing point in a refrigeration chamber containing a heat exchanger and a thermostat to activate a refrigeration to supply coolant to the heat exchanger to maintain a set temperature. Periodically defrosting the heat exchanger by introducing heat, usually by an electric heating element in the refrigeration chamber, but prior to initiating defrosting, the thermostat is taken out of control of the refrigeration unit and the latter automatically activated to effect a drop in temperature in the chamber sufficient to prevent the stored material from exceeding it permissible upper temperature during subsequent defrosting.

Abstract: A control system for a reverse cycle refrigeration system for controlling the defrosting of the outdoor coil thereof on a cost effective basis; the control system comprising a controller means receiving inputs indicative of the outdoor air temperature, the temperature of the outdoor coil, and the operation of the compressor means; the controller means having a timing function which is initiated upon the outdoor coil temperature being at or below a preselected value and the compressor means being operated; the duration of the timing function being determined on a substantially continuous basis as a function of the magnitude of the outdoor air temperature; and the controller means having an operative connection to the system so as to, upon completion of the timing function, place the reverse cycle refrigeration system into an outdoor coil defrost mode of operation.

Abstract: A refrigeration system contains a common compressor supplying refrigerant to a plurality of evaporators that are refrigerated and defrosted independently of one another. Individual refrigeration/defrost controls are provided in solid state form for the respective evaporators, and the individual controls are connected with a master control that prevents all of the evaporators from being defrosted at one time. The master control includes a digital time clock providing time signals to each of the individual refrigeration/defrost controls, and each of the individual controls can initiate a defrost operation for its respective evaporator on either a timed or demand basis. The master control includes a scanner that interrogates the individual controls in a special manner to initiate defrosting of the units in order of priority.

Abstract: An automatically-defrosting household refrigerator including a user-operable "vacation switch" effective to enable the operation of the refrigerator in a mode appropriate to a condition of zero usage. When the vacation switch is thrown to the vacation position, the user is assured at once that unnecessary energy consumption will be avoided and the likelihood of failure of the refrigerator while unattended will be diminished. The mode appropriate to a condition of zero usage includes having the interval between successive automatic defrosting operations extended. Additionally, the vacation switch may be effective to simultaneously disable an automatic icemaker, to increase the temperature set point of the thermostatic control means which maintains the temperature within the refrigerator to disable anti-condensation heaters, and to disable butter conditioner heaters.There is further disclosed a particular means for extending the interval between successive automatic defrosting operations.

Abstract: A demand defrost control system which responds to whether a predetermined evaporator temperature is reached during a defrosting operation. If the predetermined temperature is not reached, then a relatively shorter interval before the next defrosting operation is established. If the predetermined temperature is reached, then a relatively longer interval before the next defrosting operation is established.

Abstract: The invention relates to a refrigeration assembly and particularly to defrosting apparatus therefor. The assembly includes a bellows operated thermostatic motor switch responsive to evaporator temperatures for operating the compressor motor. After a predetermined number of operating cycles of the compressor the defrost apparatus is actuated. There is a linkage between the bellows and the motor switch with a main spring acting thereon to oppose the bellows and a differential spring acting thereon to assist the bellows. The differential spring is made inoperative by the defrosting unit during the defrost setting. The main spring and the differential spring are calibrated so that when both springs are effective the motor switch is actuated at a predetermined evaporator temperature. When only the main spring is effective during the defrost setting the motor switch is actuatable at an evaporator temperature higher than the above referred to temperature.

Abstract: A demand defrost control system which bases the interval between future defrosting operations on the time (heater ON time) required for the defrost heater to raise the evaporator temperature to a predetermined temperature during a previous defrosting operation. There is an inverse relationship between heater ON time and defrost intervals. Additionally, an override is provided which measures the time the compressor and evaporator are energized during any single operation cycle. If this time exceeds a predetermined length of time, the interval before the next defrosting operation is shortened.

Abstract: A refrigeration system contains a common compressor supplying refrigerant to a plurality of evaporators that are refrigerated and defrosted independently of one another. Individual refrigeration/defrost controls are provided in solid state form for the respective evaporators, and the individual controls are connected with a master control that prevents all of the evaporators from being defrosted at one time. The master control includes a digital time clock providing time signals to each of the individual refrigeration/defrost controls, and each of the individual controls can initiate a defrost operation for its respective evaporator on either a timed or demand basis. The master control includes a scanner that interrogates the individual controls in a special manner to initiate defrosting of the units in order of priority.

Abstract: A defrost control scans, in a predetermined sequence, the several evaporators of a refrigeration system of the type that is installed in a supermarket and that typically comprises a series of refrigerated food display cases in which the evaporators are mounted. Individual to each evaporator is a defrosting means and a sensing device that operates to put the defrosting means in a standby, ready-to-operate condition whenever it senses that the evaporator is in need of defrost. When the control means reaches, in the scanning sense, an evaporator whose defrosting means has been placed in a ready-to-operate condition, it acts to initiate actual operation of the defrosting means associated with that evaporator. In these circumstances, the scanning of evaporators that follow in the predetermined sequence is temporarily arrested. This assures against overloading of the defrosting means, which may typically be of the "hot gas" type, and hence particularly sensitive to overloading.

Abstract: A method and apparatus for initiating the defrost of refrigeration equipment on demand. A defrost clock which normally controls the conventional refrigeration and defrost modes of a refrigeration system includes an auxiliary switch to cease operation of the clock motor a predetermined time prior to normal defrost initiation. The defrost clock thus remains in the refrigeration mode until the demand defrost sensor switch, or an optional demand switch, initiates a defrost cycle of the refrigeration equipment. The closure of the demand defrost switch or the optional switches causes the defrost clock motor to run for a predetermined short period of time. The defrost clock switch subsequently closes slightly prior to initiation of a defrost to guarantee that the clock runs throughout the defrost mode. Thereafter, the defrost clock controls the length of the defrost and will terminate defrost upon a signal from a thermostat, or by a time signal, or a pressure signal.

Abstract: A selectable cycle defrost timer having two timing cams and two timing switches that are switched from first to second switch positions by the respective cams. The two cams rotate different numbers of times in a given time period, but the two switches are simultaneously in their second switch positions just once each given time period. Interconnection means between the two switches permits the timer to be connected into a defrost control system in such a manner that a selectable switch permits a normal defrost operation of several defrost cycles per day, or alternatively, just one energy saving defrost cycle per day.

Abstract: The electrical control panel for a refrigeration unit using single or three phase power. The control portion has an oil pressure safety switch, defrost timer, temperature controls and perhaps a refrigerant pressure control in conjunction with the normal internal overload circuit breakers for the compressor. After operation of the refrigeration unit for a period of time, a defrost control device cuts off the compressor and turns on the electric defrost heaters. As the evaporator coils are defrosted, defrost thermostats open the defrost heater supply circuits. When the current sensing relay senses that all the defrost heaters have been shut off via the defrost thermostats, a time delay relay will return the refrigeration unit to the normal refrigeration cycle. The same current sensing relay will prevent false triggering by the oil pressure safety switch if the compressor's internal overload circuit breaker opens.

Abstract: A multiple curtain, refrigerated display case employing an energy saving air defrost system that, during the first defrost stage, draws defrosting ambient air into the refrigerated air curtain passage from both directions, and during the second defrost stage employs part of the defrost air to form a circulating air curtain over the open front of the case. The case has defrost exhaust fans in the upper rear thereof actuated by a timer simultaneously with deactuation of the guard curtain fans and the refrigeration condensing unit. The circulation fans for the refrigerated air of the case have a total propulsive capacity significantly greater than that of the exhaust fans, such refrigerated air circulation fans being upstream of the refrigeration coils in the refrigerated air curtain passage, and the exhaust fans being downstream of such coils.