Patent Application
20080060366
The present teachings will become more fully understood from the detailed description and the accompanying drawings, wherein:
The following description of the present teachings is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.
The methods and systems described herein can be applied to a wide variety of cooling units. For the purpose of illustration, though, a typical absorption refrigeration system is used that has a cold storage compartment. Those skilled in the art will understand that the illustrative refrigeration system does not limit the invention in any way, but is used only to explain the invention.
With general reference to the drawings, an exemplary absorption refrigerator 10 including a control system in accordance with the present teachings is illustrated. The refrigerator 10 includes a cooling system 11 including an absorption cooling arrangement 12 mounted on a back wall 14 of a cabinet 16. The cabinet 16 encloses an insulated compartment (not specifically shown). The cooling arrangement 12 may include conventional gas absorption cooling components. In this regard, the cooling arrangement 12 may include an absorber, an evaporator, a condenser and a generator. The generator includes a boiler tube. Insofar as the present invention is concerned, it will be understood that these basic components of the gas absorption refrigerator 10 are conventional in both construction and operation.
The cooling arrangement 12 may be controlled electrically or with a gas source. In this regard, the cooling arrangement 12 may additionally include a DC electrical heater, an AC electrical heater and a gas burner. The cooling arrangement 12 may further include a burner and control box 18. The generator and heaters may be contained within a generator enclosure or canister 20 that upwardly extends proximate the burner box 18.
As is well known in the art of absorption cooling, the coolant mixture (typically ammonia and water) is heated in the generator or boiler tube 22 to preferentially releasing ammonia vapor. From the generator, the ammonia vapor flows to the condenser. In the condenser, the ammonia vapor cools and condenses. By gravity, the cool liquid ammonia flows from the condenser and into the evaporator. In the evaporator, the liquid ammonia absorbs heat from the interior of the refrigerator 10 thereby cooling the interior of the refrigerator 10. The vaporized ammonia then flows from the evaporator to the absorber where the partially depleted water—ammonia mixture absorbs the ammonia vapor to complete the refrigeration cycle.
Heat is required to vaporize the ammonia in the ammonia—water mixture. The heat source may be an electrical heater, a burner flame, or any other conventional heat source. More particularly, the electric heater may be either an A/C (e.g., 240 V.A.C.) or a D.C. (e.g., 12-48 V.D.C) heater. In the alternative, both types of electrical heaters and a burner flame may be provided with controls to allow the user to switch between the three sources of heat. When the refrigerator 10 is operating with the electrical heat source a relatively large quantity of electrical power must be supplied from a source external to the refrigerator 10 (e.g. from the recreational vehicle electrical system or from a hook up provided at the camp site). In certain applications, the refrigerator 10 may automatically choose the best available energy source upon which to operate.
It is desirable to operate the generator of the cooling arrangement 12 within an optimum temperature range. Accordingly, the present inventors recognized a need to monitor a temperature condition of the generator and control the cooling arrangement 12 when the generator temperature condition is outside an optimum temperature range, thereby improving the cooling performance efficiency of the cooling arrangement 12 inside the refrigerator 10.
Turning now to the schematic illustration of
The circuit 25 may operate to control the control device 24 to turn off the source of heat to generator or boiler tube 22 when a second temperature exceeds a predetermined temperature condition. The predetermined temperature condition may simply be a predetermined temperature. It will be noted that the predetermined temperature may be significantly above the optimum operating range of the generator temperature. The circuit 25 may alternatively or additionally operate to maintain the generator temperature substantially within the optimum operating range. In this regard, the circuit 25 may operate to reduce the source of heat to the generator upon detection of a generator temperature above the optimum operating range. The source of heat may be reduced by temporary interruption of the power source (e.g., the power to the unit 10 or the gas source) until such time that the generator temperature is sufficiently within the optimal operating range. Conversely, the circuit 25 may operate to increase the source of heat to the generator upon detection of a generator temperature below the optimum operating range.
In
The mounting bracket 36 may include a first portion or lower portion 38 that may be secured to the burner box 18. The lower portion 38 may be secured with discrete fasteners 40, through welding, or in any other suitable manner. The mounting bracket 36 may additionally include an upper portion 44 to which the sensor 24 may be mounted. The mounting bracket 36 may be constructed from metal. Importantly, the sensor 24 is positioned within the canister 20 proximate the generator or boiler tube 22.
Turning to
The canister bracket 50 may include a sensor mounting portion 56. The sensor mounting portion 56 may be inwardly displaced from a cylindrical wall 58 of the canister bracket 50. The sensor mounting portion 56 may include a general planar segment 60 to which the sensor 24 may be conventionally attached. Importantly, the sensor 24 is positioned within the canister 20 for sensing of the generator temperature.
As shown in
Turning to
Turning to
During operation, the circuit 25 receives signals representative of the temperature of the generator 22 from the temperature sensor 24. If a sensed generator temperature condition is calculated to be above the predetermined temperature condition, the circuit 25 may operate the control device 26 or 66. In this regard, the sensed generator temperature condition may simply be the sensed generator temperature and the predetermined temperature condition may simply mean a predetermined temperature. Alternatively, the sensed temperature condition may be a function of elapsed time within one or more temperature bands above a predetermined temperature. In this scenario, the predetermined temperature condition may be a predetermined time within on or more temperature bands above the predetermined temperature. In this regard, impact to the generator performance may be significantly more critical at increasingly higher temperatures above the predetermined temperature. In such an arrangement, a computer may continuously calculate the sensed temperature condition.
The refrigerator 10 may incorporate a three-way heat supply including both an A.C and a D.C. heater along with a fuel system for the fire heat source. Accordingly, a relay may be provided to open the current paths to the A.C. and D.C. heaters and to close the valve 66, thereby ensuring that the three heat sources are each turned off when it is desired to stop driving the generator. Note also, that if it should become necessary to turn off the heat source(s), the circuit 25 may illuminate a monitor (not shown) to alert the user to the possibility that the refrigerator 10 may need attention and/or maintenance. Thus, those skilled in the art will recognize that reference to opening and closing the valve 66 includes turning the electric heaters off and on (e.g., through opening and closing of the switch 26) as applicable. Conversely, reference to turning the electric heaters off and on includes opening and closing the valve 66.
In the event that the sensed temperature condition of the generator remains above the predetermined temperature condition, the circuit 25 may suspend further heating of the generator 22. When the condition clears, the circuit 25 may resume commanding the control device 26. In certain applications, the control system 11 may operate such that the control device 26 renders further heating of the generator impossible until the control system 11 is reset. For such applications, a reset switch may be provided to reset the circuit 25. The reset switch may be a push button switch. Alternatively, the reset switch may be a toggle switch or any other well known device capable of generating a binary (i.e., on/off) signal for the circuit. Upon being reset, the circuit 25 clears the control system 11 and begins monitoring the temperature sensor 24 anew. The circuit 25 may include a memory for storing an indication of whether the sensed temperature condition of the generator exceeded the predetermined temperature condition. The memory may be a flip flop, a relay, RAM or any conventional device capable of storing a binary state. Resetting of the circuit 25 may require authorized maintenance of the refrigerator 10.
In alternative embodiments, if the circuit closes the valve 66 or opens the switch 26 because the sensed temperature condition of the generator 22 is above the predetermined temperature condition, the circuit 25 may wait for pre-selected time. At the end of the time, the circuit 25 may then re-open the valve 66 (or the switch 26) and allow the heat source to resume driving the cooling system 12. If the predetermined temperature condition is again exceeded, the circuit 25 may then close the valve 66 (or open the switch 26) again. Moreover, because two attempts to produce the desired performance appear to have not succeeded, the circuit 25 preclude further heating of the generator.
Turning now to
Accordingly, it will be understood that a control arrangement or the present teachings may be incorporated into a passive in-line device for a refrigerator 10. In this regard, the present teachings may be utilized without a need to modify normal refrigerator controls by simply interrupting a source of heating power upon sensing of a predetermined temperature condition. Alternatively, the present teachings may be incorporated into a microprocessor configured to receive a signal indicative of a predetermined sensed temperature condition. The microprocessor may accordingly control the refrigerator otherwise in the manner discussed herein.
Turning to
The description of the invention is merely exemplary in nature and, thus, variations that do now depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.
