JP2000304396A - Hybrid refrigerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide means for stably holding the cooling or heating temp. of a hybrid refrigerator. SOLUTION: A compressor 11 compresses a vapor refrigerant evaporated by an evaporator 14 and sends it to a condenser 12. The condenser 12 cools the vapor refrigerant from the compressor to condense it into a liq. refrigerant. The condensed high-pressure liq. refrigerant is changed through an expansion valve 13 to a low pressure one and sent to the evaporator 14. The evaporator 14 at low pressure evaporates the liq. refrigerant, thus constituting a refrigeration cycle for absorbing heat from surroundings. A specified current is caused to flow from a power source 22 to the evaporator 14 by bringing one junction of a Peltier element 21 into thermal contact and the other junction is, e.g. cooled to cool the interior 31a of a covered box 31 through a heat exchanger 25 such as absorbing fins attached to this junction. A heat storage body 24 composed of a Cu thick plate or the like having a high thermal conductivity and a high specific heat is set between the evaporator 14 in the refrigeration cycle and one junction of the Peltier element 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hybrid refrigerator capable of stably maintaining a cooling or heating temperature.

[0002]

2. Description of the Related Art Peltier elements are frequently used because they have no moving parts and can control the temperature of cooling (or heating) with high accuracy. In this Peltier element, COP (Coefficent of Performance) of cooling (or heating)
Because of its small size, sufficient cooling or the like cannot often be performed depending on the purpose. In such a case, a hybrid refrigerator that can obtain a large temperature difference by a refrigeration cycle using a refrigerant and perform stable temperature control by a Peltier element is conceivable. In such a hybrid refrigerator, generally, one joint of a Peltier element is brought into thermal contact with an evaporator of a refrigeration cycle, and the other joint cools (or heats) an object.
Will be done. However, temperature control performed on the refrigeration cycle side to cope with fluctuations in heat load or the like is inaccurate, and as a result, the temperature of one junction of the Peltier element also fluctuates greatly. In addition, it is difficult to control the temperature of the object within a predetermined temperature range.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide means for easily and stably maintaining the cooling or heating temperature of a hybrid refrigerator.

[0004]

Means for Solving the Problems A compressor for compressing and sending vapor refrigerant evaporated by an evaporator, a condenser for cooling and condensing the vapor refrigerant sent from the compressor, A refrigeration cycle consisting of an expansion valve that sends high-pressure liquid refrigerant to a low-pressure evaporator, an evaporator that cools the surroundings by evaporating the liquid refrigerant sent through the expansion valve, and two junctions that perform cooling or heating depending on the direction of current In a hybrid refrigerator in which one of the Peltier elements is brought into thermal contact with the evaporator of the refrigeration cycle and the other is cooled or heated, the junction between the evaporator and the Peltier element is provided. A heat storage body having a high thermal conductivity and a large specific heat is interposed therebetween.

The joint between the evaporator, the heat storage element and the Peltier element that comes into contact with the evaporator is covered with a heat insulating material that is thermally isolated from the other joint of the Peltier element.

[0006] The heat storage body is formed of a thick plate of a copper plate.

A power supply for driving the Peltier element performs defrosting at predetermined time intervals or in accordance with a signal from frost adhesion detection means for detecting the adhesion of frost to the cooling section by reversing the current flowing through the Peltier element. Provide a defrost function.

[0008] The frost adhesion detecting means is a temperature detecting means for detecting the temperature of each of the two joints of the Peltier element, a temperature difference calculating means for calculating a difference between the temperatures, and comparing the calculated temperature difference with a predetermined value. It is determined that frost has adhered when the temperature difference between the two joints of the Peltier element is equal to or higher than a predetermined temperature.

The temperature detecting means for detecting the temperature of each of the two junctions of the Peltier element includes a temperature sensor for detecting the temperature of one of the junctions, and a temperature, a voltage and a current of the Peltier element, and a physical constant of the Peltier element. It comprises a temperature calculator for calculating the temperature of the other joint.

[0010] The temperature calculating section receives the temperature of one junction of the Peltier element, the voltage and current of the Peltier element, and the physical constant of the Peltier element as inputs, and outputs the LUT (Look) which outputs the temperature of the other junction of the Peltier element. Up Table).

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a conceptual diagram of one embodiment of a hybrid refrigerator according to the present invention. Consider a thermostat that cools the inside 31a of the covered box body 31 made of a heat insulating material or the like to a predetermined temperature. In the compressor 11, the vapor refrigerant evaporated in the evaporator 14 is compressed and sent to the condenser 12. In the condenser 12, the vapor refrigerant sent from the compressor is cooled and condensed to be a liquid refrigerant. The condensed high-pressure liquid refrigerant is reduced in pressure through the expansion valve 13 and sent to the evaporator 14. Low pressure evaporator 14
The liquid refrigerant evaporates and absorbs heat from the surroundings,
A refrigeration cycle is configured. One of the joints of the Peltier element 21 is brought into thermal contact with the evaporator 14 so that
Then, a predetermined current is passed through the cooling device to cool the other joint, for example, and cool the inside 31a of the closed box 31 via the heat exchanger 25 including heat absorbing fins provided at the joint. Between the evaporator 14 of the refrigeration cycle and one joint of the Peltier element 21, a heat storage body 24 made of a thick copper plate or the like and having high heat conductivity and high specific heat is interposed. As a result, the refrigeration cycle is turned on and off, and the evaporator 14 is controlled.
Even if the temperature of the Peltier element 21 greatly fluctuates, the temperature of one of the joints on the heat radiation side of the Peltier element 21 is averaged by the heat storage unit 24 and becomes substantially constant, and the temperature of the other joint on the cooling side also fluctuates accordingly. Will not be done. In addition, a heat insulator 31b is provided around the joint on the heat radiation side of the evaporator 14, the heat storage body 24, and the Peltier element 21 connected to the evaporator 14, so as to be thermally isolated from the joint on the cooling side of the Peltier element 21.

When the above-mentioned closed box 31 is, for example, a refrigerator or the like, it adheres to the heat exchanger 25 at predetermined time intervals or according to a signal from frost adhesion detecting means for detecting the adhesion of frost to the cooling section. The frost needs to be removed. In this case, defrosting is performed by flowing the current of the Peltier element 21 in the power supply 22 for driving the Peltier element 21 at predetermined time intervals or in reverse by a signal from the frost adhesion detection means for a predetermined time. Provide a defrost function. By flowing the current of the Peltier element 21 in reverse for a predetermined time, heat is generated at the junction on the cooling side and defrosting is performed. At this time, the junction on the heat radiation side and the heat storage body 24 in contact with the junction are cooled. You.
Then, after returning to the original current direction after a predetermined time, the heat storage body 2
Since the heat radiation side is cooled by 4, the temperature of the junction on the cooling side is rapidly cooled, and the inside 31a of the closed box body 31 can be quickly returned to the original temperature.

As the frost adhesion detecting means, a conventional technique can be used. Alternatively, a means suitable for this configuration can be adopted as follows. That is, if frost adheres to the heat exchanger 25 on the cooling side of the Peltier element 21, the amount of heat absorbed decreases, and the temperature difference between the junction of the cooling side and the radiation side of the Peltier element 21 increases. Therefore, a Peltier element is provided by providing temperature detecting means for detecting the temperatures of both of these junctions, temperature difference calculating means for calculating the difference between the temperatures, and comparing means for comparing the calculated temperature difference with a predetermined value. It is determined that frost has adhered when the temperature difference between the two joints 21 is equal to or higher than a predetermined temperature. FIG. 2 is a schematic block diagram of the power supply 22 of the Peltier device 21 including these functions. The current control unit of the power supply 22 inputs the temperature Tc on the cooling side of the Peltier element 21, calculates a current value by PID control or the like to keep the temperature at a predetermined temperature, and sends the current to the Peltier element 21. The temperature Tc on the cooling side of the Peltier element 21 includes, for example, a temperature Th on the heat radiation side detected by a temperature sensor 23 composed of a thermistor or the like, a current I and a voltage V of the Peltier element 21 detected by an ammeter 22c, a voltmeter 22d, and the like. Using the Seebeck coefficient S and the resistance R of the element 21, the temperature can be calculated by the temperature calculation unit 22 a using V = S × (Th−Tc) + R × I. Temperature calculator 22a
Is an LUT composed of a ROM that uses, for example, a temperature Th, a current I, and a voltage V as address inputs and a temperature Tc as a data output.
Can be composed of

The frost adhesion detecting means 26 includes a Peltier device 21
And a comparing section 26b as a comparing section for comparing the calculated temperature difference with a predetermined value. The above temperature calculation unit 22a and the temperature sensor 23
Are input to the difference unit 26a to calculate the temperature difference between them. The calculated temperature difference is compared with the comparison unit 26.
When the temperature difference is larger than the predetermined value, the frost adhesion signal F is output. The frost adhesion signal F is supplied to the current control unit 22.
b, when the frost adhesion signal F is true, the Peltier element 2
The current flowing through the heat exchanger 1 is reversed for a predetermined time to remove frost attached to the heat exchanger 25.

[0015]

As described above, the compressor for compressing and sending out the vapor refrigerant evaporating from the evaporator, the condenser for cooling and condensing the vapor refrigerant sent from the compressor, An expansion valve that sends high-pressure liquid refrigerant from the device to a low-pressure evaporator, and a refrigeration cycle consisting of an evaporator that evaporates the liquid refrigerant sent through the expansion valve and cools the surroundings.
A hybrid refrigeration system comprising a Peltier element consisting of two junctions for cooling or heating depending on the direction of electric current, wherein one junction of the Peltier element is brought into thermal contact with the evaporator of the refrigeration cycle and the other junction is cooled or heated. The heat exchanger with high thermal conductivity and high specific heat is interposed between the evaporator and the junction of the Peltier element to cool the hybrid refrigerator regardless of the temperature change of the evaporator in the refrigeration cycle. Alternatively, the heating temperature can be stably maintained.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of one embodiment of a hybrid refrigerator according to the present invention.

FIG. 2 is a schematic block diagram of a power supply of a Peltier device of one embodiment of the hybrid refrigerator according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Compressor 12 Condenser 13 Expansion valve 14 Evaporator 21 Peltier element 22 Power supply 22a Temperature calculation unit 22b Current control unit 22c Ammeter 22d Voltmeter 23 Temperature sensor 24 Heat storage unit 25 Heat exchanger 26 Frost adhesion detection means 26a Difference unit 26b Comparison section 26c Constant power supply 31 Covered box

Claims (7)

[Claims] 1. A compressor for compressing and sending vapor refrigerant evaporated from an evaporator, a condenser for cooling and condensing the vapor refrigerant sent from the compressor, and a high-pressure liquid refrigerant from the condenser. A refrigeration cycle consisting of an expansion valve that sends air to a low-pressure evaporator, an evaporator that cools the surroundings by evaporating the liquid refrigerant sent through the expansion valve, and a Peltier that consists of two joints that perform cooling or heating depending on the direction of electric current In a hybrid refrigerator in which one of the Peltier elements is brought into thermal contact with the evaporator of the refrigeration cycle and the other is cooled or heated, heat is applied between the evaporator and the Peltier element junction. A hybrid refrigerating machine characterized by interposing a heat storage body having high conductivity and high specific heat. 2. The structure according to claim 1, wherein the junction between the evaporator, the heat storage element and the Peltier element in contact with the evaporator is covered with a heat insulating material that is thermally insulated from the other junction of the Peltier element. The hybrid refrigerator as described. 3. The hybrid refrigerator according to claim 1, wherein the heat storage body is formed of a thick copper plate. 4. A power supply for driving the Peltier element is defrosted by reversing a current flowing through the Peltier element at predetermined time intervals or by a signal from frost adhesion detection means for detecting the adhesion of frost to the cooling unit. The hybrid refrigerator according to claim 1, further comprising a defrosting function for performing the defrosting. 5. A frost adhesion detecting means comprising: a temperature detecting means for detecting the temperature of each of the two joints of the Peltier element; a temperature difference calculating means for calculating a difference between the temperatures; 5. The hybrid refrigerator according to claim 4, wherein the temperature difference between the two joints of the Peltier element is equal to or higher than a predetermined temperature, and it is determined that frost has adhered. . 6. A temperature sensor for detecting the temperature of each of the two junctions of the Peltier element, a temperature sensor for detecting the temperature of one of the junctions, the temperature and the voltage and current of the Peltier element, and the physical characteristics of the Peltier element. 6. The hybrid refrigerator according to claim 5, further comprising a temperature calculator for calculating the temperature of the other junction from the constant. 7. The LUT which receives the temperature of one junction of the Peltier element, the voltage and current of the Peltier element, and the physical constant of the Peltier element as inputs, and outputs the temperature of the other junction of the Peltier element as an output. 7. The hybrid refrigerator according to claim 6, comprising a (Look Up Table).