JPH0545011A - Cooling device of automatic vending machine - Google Patents

Abstract

PURPOSE:To provide a stable circulation of refrigerant and reduce a running cost of a cooling device by a method wherein an amount of blowing air to a condensor is adjusted in response to a variation of a surrounding air temperature or load. CONSTITUTION:A refrigerant temperature at an outlet of a condensor 1 is detected by a temperature sensor 6, and a surrounding air temperature is detected by a temperature sensor 7. A control part 9 may adjust an amount of air blown toward the condensor 1 in response to each of the detected temperatures, adjust a heat exchanging amount at the condensor 1 and make an amount of circulating refrigerant to an appropriate value. With such an arrangement, a surplus power consumption can be eliminated and its running cost can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling device for a vending machine using a capillary as a refrigerant throttle.

[0002]

2. Description of the Related Art In order to simplify the structure and reduce the cost of a cooling device for an automatic vending machine, the refrigerant is throttled by a capillary without providing an expansion valve for adjusting the flow rate of the refrigerant. The small cooling device with such a structure does not adjust the flow rate of the refrigerant as it is, and when the outside air temperature is low or the cooling load is small like in winter, the cooling capacity becomes relatively large and the condensation Most of the refrigerant sent to the vessel is condensed at the inlet of the condenser. Therefore, the amount of the refrigerant sent to the evaporator is reduced, resulting in poor cooling. This is the so-called "cat" phenomenon.

Therefore, a conventional cooling device for a vending machine is
In order to prevent "catching", it is configured as shown in FIG.
That is, the heater 10 is installed in front of the condenser 1, and the thermostat 11 for controlling the operation of the heater 10 is also installed. When the outside air temperature becomes low, the heater 10 is operated to heat the condenser 1 so that warm air is supplied to the condenser 1. Supply. When hot air is supplied to the condenser 1, the temperature difference between the condenser 1 and the internal refrigerant becomes small,
The amount of heat exchange becomes smaller accordingly. As a result, the condensation of the refrigerant is almost completed at the outlet of the condenser 1 despite the decrease in the outside temperature, and the normal circulation amount of the refrigerant can be maintained to prevent the occurrence of cooling failure. In the figure, 2 is a capillary, 3 is an evaporator, 4 is a compressor, 5 is a fan, and 12
Is the main body of the vending machine.

[0004]

By the way, the above-mentioned conventional cooling device can prevent "catching" in response to fluctuations in the outside temperature, but the outside temperature is always set except for one period in summer. Since the temperature is lower than the temperature, the heater 10 is energized most of the year. The power consumed by the heater 10 is not used for cooling. Moreover, the amount of heat generated by the heater 10 is added to the compressor 4 as an extra load in the heat cycle, and the electric power is consumed twice.

That is, during the period when the outside air temperature is lower than the operating temperature of the heater 10, as compared with during the summer when the heater is not energized,
The power consumption increases by the amount consumed by the heater 10. Moreover, despite the fact that the cooling load decreased during that time,
Since the compressor 4 is heated by the heater 10, the power consumption is kept substantially constant. As described above, during most of the year, there is a problem that extra power is consumed even though the cooling load is small and the running cost is high.

Further, since the operation of the heater 10 is controlled only by the fluctuation of the outside temperature, the fluctuation in the refrigeration cycle can be reduced, but the response to the fluctuation of the outside temperature becomes slower and the cooling other than the outside temperature can be achieved. There is a problem in that it is not possible to deal with the shortage of the circulating amount of the refrigerant due to the load fluctuation or the like. The present invention has been made to solve the above problems, and an object of the present invention is to realize efficient cooling in a heat cycle and eliminate wasteful power consumption.
It is to provide a cooling device for a vending machine with a reduced running cost.

[0007]

In order to achieve the above object, the present invention provides a cooling device for a vending machine which liquefies a refrigerant compressed by a compressor by a condenser and sends it to an evaporator through a capillary. Based on the temperature sensor that detects the air temperature, the temperature sensor that detects the refrigerant temperature at the outlet of the condenser, and the detection values of both sensors, the heat exchange amount of the condenser will be the optimum value according to the cooling load and the outside air temperature. Thus, a control unit for adjusting the amount of air blown to the condenser is provided.

[0008]

In the present invention, the amount of air blown to the condenser is adjusted according to the cooling load and the outside air temperature based on the outside air temperature detected by each temperature sensor and the refrigerant temperature at the condenser outlet, and the heat exchange of the condenser is performed. The amount is optimal.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the configuration of an embodiment of the present invention. In the figure, 1 is a condenser, 2 is a capillary, 3 is an evaporator, 4
Is a compressor, 5 is a fan driven by a DC motor, 6
Is a temperature sensor for detecting the temperature of the refrigerant on the outlet side of the condenser 1,
Reference numeral 7 is a temperature sensor for measuring the outside air temperature, 8 is a DC chopper that outputs a variable voltage and operates the fan 5 at a variable speed, 9 is a control unit, and 12 is a vending machine body.

With this configuration, the temperature of the refrigerant detected by the temperature sensor 6 and the outside air temperature detected by the temperature sensor 7 are input to the control unit 9. The control unit 9 calculates the operation amount of the fan 5 from the refrigerant temperature and the outside air temperature, and the DC chopper 8
Send to. The DC chopper 8 converts the value of the operation amount into a DC voltage and sends it to the fan 5 to operate the fan 5 at a variable speed. Thereby, the amount of air blown to the condenser 1 is adjusted, and the heat exchange amount of the condenser 1 is adjusted to an appropriate value so as not to be in a "catching" state in which the circulation amount of the refrigerant decreases. The control unit 9
The specific content of the adjustment of the air flow rate of the fan 5 by means of the method is to decrease the output voltage of the DC chopper 8 and decrease the rotation speed of the fan 5 according to the extent of the decrease in the outside air temperature. At the same time, the refrigerant temperature is monitored and the rotation of the fan 5 is controlled until the temperature returns to the proper temperature. Regarding the control of the fan 5, it is also possible to control the rotation on / off to adjust the blown air amount.

Even when the outside air temperature is lowered by these controls, or when the cooling load is reduced and the refrigerant temperature is about to be lowered, both the normal refrigerant temperature and the proper refrigerant circulation amount are maintained and "catching" occurs. Is eliminated. Also,
The configuration of the embodiment also has a temperature sensor 6 and a DC as compared with the conventional device.
Since only relatively inexpensive parts such as the chopper 8 are added, the power consumption can be reduced and the running cost can be reduced with a slight increase in the initial cost.

FIG. 2 is a block diagram when the control unit 9 is fuzzy control. From the outside air temperature and the condenser outlet temperature input to the control unit 9, the fuzzy inference unit 91 obtains the optimum fan rotation speed 92 based on the fuzzy rule input in advance and sends it to the external DC chopper 8. Figure 3
Shows a specific example of the membership function for the outside temperature of the antecedent part set in the fuzzy inference unit 91.

Here, the outside air temperature has four levels of membership functions of “low”, “slightly low”, “slightly high”, and “high”, and the certainty μ (0 ≦ μ) for each detected outside air temperature. Find ≦ 1). Further, the operation amounts C _{1 to} C ₄ for the fan 5 with respect to these outside temperatures are set to the values shown in the following table.

[0014]

[Table 1]

As a result, the fan operation amount X _{1 with} respect to the change in the outside temperature can be obtained from the following equation.

[0016]

[Equation 1]

FIG. 4 shows a specific example of the membership function for the antecedent condenser outlet temperature set in the fuzzy reasoning section 91. Again, the condenser outlet temperature is determined by using the four-step membership functions of “low”, “slightly low”, “slightly high”, and “high”, and the certainty μ (0 ≦ μ ≦ 1) is asked. Also,
The operation amount C ₅ -C ₈ fans 5 for the values of these condenser outlet temperature, the values shown in the following table is set.

[0018]

[Table 2]

As a result, the fan operation amount X _{2 with} respect to the change in the condenser outlet temperature is obtained by the following equation.

[0020]

[Equation 2]

Further, as a consequent part, the required fan operation is performed.
Crop X₁, X₂Into the following equation to obtain the final fan operation amount
u is required. u = 0.8X₁+ 0.2X₂  In this formula, the manipulated variable X depending on the outside temperature₁The weighting of
Operation amount of condenser outlet temperature X₂4 times, but both
The weighting of is arbitrarily changed according to the characteristics and conditions of the cooling device
it can. In this way, the outside air temperature
Therefore, the fan operation amount should be determined according to the changes of both.
As a result, the amount of heat exchange in the condenser 1 is smaller than in the past.
Finely adjusted to prevent "catching".
Moreover, the fluctuation of the refrigeration cycle is reduced as a whole,
Stable operation becomes possible.

[0022]

As described above, according to the present invention, the amount of air exchanged to the condenser is appropriately adjusted based on the outside air temperature and the refrigerant temperature at the condenser outlet, so that the heat exchange amount of the condenser can be improved. It becomes an optimum value, and the circulation amount of the refrigerant becomes stable. As a result, the heater for heating, which has been conventionally installed, is no longer needed, and wasteful power consumption in the heat cycle is eliminated, and the running cost can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an exemplary embodiment of the present invention.

FIG. 2 is a block diagram showing the inside of a control unit.

FIG. 3 shows a specific example of a membership function set in a fuzzy inference unit.

FIG. 4 shows a specific example of a membership function set in a fuzzy inference unit.

FIG. 5 is an explanatory diagram showing a structure of a conventional example.

[Explanation of symbols]

 1 Condenser 2 Capillary 3 Evaporator 4 Compressor 5 Fan 6 Temperature Sensor 7 Temperature Sensor 8 DC Chopper 9 Controller 12 Vending Machine Main Body 91 Fuzzy Reasoning Unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiro Tsuruta 1-1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi Fuji Electric Co., Ltd.

Claims (1)

[Claims] 1. A cooling device for a vending machine, in which a refrigerant compressed by a compressor is liquefied by a condenser and sent to an evaporator through a capillary, a temperature sensor for detecting an outside air temperature, and a refrigerant temperature at an outlet of the condenser. A temperature sensor to detect, and a control unit that adjusts the amount of air blown to the condenser so that the heat exchange amount of the condenser becomes an optimum value according to the cooling load and the outside air temperature, based on the detected values of both sensors. A cooling device for a vending machine, characterized by being equipped with.