JPS6349667Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a frozen or refrigerated case for Western confectionery and other foods.In particular, it uses a rotational speed variable speed control device such as an inverter to speed up the temperature drop inside the refrigerator. This paper proposes a case that controls the refrigerator accordingly and achieves energy-saving effects.

Generally, the cooling mechanism of a refrigerated case is composed of a commercially available condensing unit, an expansion mechanism, and a cooler, and the cooling capacity is determined by the evaporation temperature of the refrigerant and the rotation speed of the compressor. Therefore, when the temperature inside the refrigerator reaches the set temperature, the compressor is stopped by the temperature controller, and then when the temperature inside the refrigerator rises, the compressor is started, and so on. Controls internal temperature. Therefore, a large amount of starting current flows each time the compressor is started. Furthermore, since the condenser fan is running at full capacity even during operation, a large amount of hot air from the condenser causes discomfort, especially in the summer. Also, when the power is turned on to the compressor (when the switch is turned on), the load on the case is large, but since the rotation speed of the compressor is a predetermined constant value, it takes time for the temperature to drop.

The present invention aims to provide a show case that has been improved in this respect, and its configuration is such that the drive circuit for the compressor drive motor and/or condenser fan drive motor used in the refrigerating or freezing show case has a low rotation speed when starting up. A rotation speed change mechanism consisting of an inverter that gradually increases the frequency to gradually increase the rotation speed to a high rotation speed, and a rotation speed change mechanism that operates at a frequency higher than the power supply frequency when starting when the temperature inside the case is higher than the set cooling temperature range. The present invention is characterized by incorporating a control device consisting of a temperature sensor and a control circuit that controls the rotation of the motor, reduces the frequency to the steady operating range when the set cooling temperature range is reached, and stops the motor drive when the set cooling temperature range is lower than the set cooling temperature range. Refrigerated or frozen storage case.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a rear view of the refrigerating case, FIG. 2 is an explanatory diagram of an example of an operating circuit, and FIG. 3 is an explanatory diagram of an example of the operation of an inverter.

In FIGS. 1 and 2, 1 is an inverter;
2 is a compressor, 3 is a condenser, 4 is a condenser fan, 5 is an expander, 6 is a cooler, 7
is a temperature sensor, 8 is a control circuit, and 9 is a power switch. When the power switch 9 is turned on, the inverter 1 gradually increases its output frequency (Fig. 3a).
), the rotational speed of each drive motor of the compressor 2 and condenser fan 4 is increased according to the output frequency thereof. Therefore, excessive rush current at startup can be prevented. The output frequency is controlled by a control circuit 8 based on a temperature sensor 7 inside the show case.
It is controlled as shown in the figure.

In Figure 3, the upper part shows the output frequency Hz and time T.
The lower part shows the relationship between the set temperature and time T, the upper part between 30 and 50 Hz shows the steady operation range, the lower part K shows the set cooling temperature, and K' and K'' show the set cooling temperature control range. .

Further explaining the control with reference to Fig. 3, when the power switch 9 is turned on, the output frequency is gradually increased (see a), and when the temperature inside the show case is high, it is possible to increase the output frequency from the normal operating range (30 to 50 Hz as an example in the figure). The compressor 2 and condenser fan 4 are powerfully driven by this high frequency output to quickly cool the inside of the show case. In this case, since the rotation gradually increases, even though the starting current at starting is increased to a high frequency, the starting current can be started without flowing excessively as in the conventional case.

When the temperature inside the show case falls to a control range K' near the set temperature K, the output frequency is controlled to drop to the steady operating range (50 to 30 Hz) as shown at point c. Depending on the load and set temperature, it is possible to maintain a constant temperature, and the current can also be kept low as shown in d.

Below the set cooling temperature control range due to load reduction
K'' or lower, the temperature controller (temperature sensor 7 and control circuit 8) temporarily eliminates the output of inverter 1 (see point e), and then when the temperature inside the case reaches the set cooling temperature K, inverter 1 is turned off again.
The operation starts and is then controlled in an on-off manner. In this case as well, the inverter output gradually increases at the time of ON startup as described above, so the startup current does not become as large as in the conventional case.

Since the temperature has already reached a certain level, the maximum frequency at startup can be controlled to a low level within the steady operation range of the inverter. Since the rotation of the condenser fan 4 is controlled in the same way as the compressor, the discomfort caused by hot air is reduced due to rotation restriction, and clogging of the condenser can also be suppressed.

As explained above, the present invention uses an inverter to increase the driving power frequency of each motor of the compressor and condenser fan to a frequency higher than the normal operating range at startup to achieve rapid cooling. This eliminates the generation of rush current, eliminates the sudden increase in current even during on-off operation during continuous operation, and allows low-load operation, which is superior to conventional products. It is an on-off operation of rated frequency control (see Figure 3 X),
There were various problems such as excessive inrush current flowing every time it was turned on, large current loss, and large wear and tear on equipment, but this invention can solve these problems. It is very effective.

[Brief explanation of the drawing]

The attached drawings are for explaining the embodiment of the present invention.
2 is an explanatory diagram of an example of an operating circuit, and FIG. 3 is an explanatory diagram of an example of an inverter's operation. 1...Inverter, 2...Compressor, 3
...Condenser, 4...Condenser fan,
5... Expander, 6... Cooler, 7... Temperature sensor, 8... Control circuit, 9... Power switch.

Claims (1)

[Scope of utility model registration request] A rotation speed change mechanism including an inverter for gradually increasing the frequency of a compressor drive motor and/or a condenser fan drive motor used in a refrigerating or freezing case so as to gradually increase the rotation speed from a low rotation speed at start-up to a high rotation speed;
The rotational speed change mechanism rotates at a frequency higher than the power supply frequency when started when the temperature inside the case is higher than the set cooling temperature range, drops to a frequency within the normal operating range when the temperature reaches the set cooling temperature range, and stops the motor drive when the temperature falls below the set cooling temperature range. This refrigerated or freezer case is characterized by incorporating a control device consisting of a temperature sensor and a control circuit that controls the rotational speed change mechanism so that the rotational speed change mechanism rotates at a frequency higher than the power supply frequency when started when the temperature inside the case is higher than the set cooling temperature range, drops to a frequency within the normal operating range when the temperature reaches the set cooling temperature range, and stops the motor drive when the temperature falls below the set cooling temperature range.