JPH0541317Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to a refrigeration system capable of controlling capacity to improve pull-down performance.

[Conventional technology]

FIG. 3 is a refrigerant circuit diagram showing a conventional refrigeration system. In FIG. 3, 1 is a compressor, and 1a is an electric motor for driving the compressor 1. In FIG. The refrigerant gas compressed by this compressor is sent to a condenser 3 through a discharge pipe 2. The condenser 3 liquefies the refrigerant gas and sends this liquid refrigerant to the expansion valve 5 through the liquid pipe 4.

The expansion valve 5 is for decompressing and expanding the liquid refrigerant.
The refrigerant whose pressure has been reduced by the expansion valve 5 is sent to the evaporator 6, where it evaporates and exchanges heat with the object to be cooled. 7 is a refrigerator that stores the objects to be cooled.

The refrigerant evaporated in the evaporator 6 is transferred to the suction pipe 8
The compressor 1 is configured to return to the compressor 1 through the compressor 1.

Note that 9 is a low pressure and force detector that detects the low pressure and force of the refrigerant in this suction pipe 8, and in order to detect this low pressure and force, a low pressure and force extraction pipe 1 is connected to the suction pipe 8.
0 is concatenated. This low pressure force extraction piping 10
A low-pressure force detector 9 is provided.

The frequency converter 11 determines the output frequency based on the command from the low pressure and force detector 9.

In the refrigeration system configured and operated as described above, when high-temperature items are placed in the refrigerator 7 and when the evaporator 6 is pulled down after defrosting, the low pressure increases. The force detector 9 detects low pressure and force from the low pressure and force extraction pipe 10, compares it with a set value, and instructs the frequency converter 11 to increase the frequency, thereby increasing the output frequency and increasing the output frequency of the drive motor 1a. Increase the rotation speed.

As a result, the low pressure is reduced to the set value and cooling operation is performed. Note that this low pressure setting value sets the required pressure in a state where the cooling operation is stable.

[Problem that the invention attempts to solve]

In the above conventional refrigeration equipment, the pressure setting value is constant even when the internal temperature is high, so the frequency is increased and when the set value is reached, the frequency stops increasing, so the cooling rate (pulldown) is gradual. becomes.

In addition, due to the increase in load, the suction pipe 8
The pressure loss of the evaporator 6 increases and the evaporation pressure of the evaporator 6 becomes high, which also causes the problem that the cooling rate becomes slow.

On the other hand, as a solution to this problem, there is a method of lowering the set pressure to a level higher than the required pressure, but there is a problem in that even in a stable state, the low pressure force is unnecessarily lowered, resulting in inefficient operation.

This idea was made to solve these problems, and it not only speeds up the pulldown, but also
The purpose is to obtain a refrigeration system that can obtain optimal low pressure and force even in a stable state.

[Means for solving problems]

The refrigeration system according to this invention is provided with a temperature sensor inside the refrigerator that lowers the low pressure set value of the low pressure force detector by a predetermined amount when the temperature inside the refrigerator is higher than a predetermined value.

[Effect]

In this device, when the temperature inside the refrigerator becomes higher than a predetermined temperature, the temperature sensor lowers the pressure setting value of the low pressure and pressure detector by a predetermined amount, thereby increasing the output frequency of the frequency converter. It acts so that it is quickly pulled down.

〔Example〕

Hereinafter, embodiments of the refrigeration system of this invention will be described based on the drawings. FIG. 1 is a refrigerant circuit diagram showing the configuration of one embodiment. In FIG. 1, parts that are the same as those in FIG. 3 are given the same reference numerals to avoid duplication, and their explanation will be omitted, and the explanation will focus on the parts that are different from FIG. 3.

As is clear from comparing FIG. 1 with FIG. 3, in FIG.
2 is provided, and the detected force of this temperature sensor 12 is sent to the low pressure force detector 9. The other configurations are the same as in FIG. 3.

Next, the operation will be explained. The operation of the cooling operation is the same as that shown in FIG. 3, and the explanation thereof will be omitted.

Next, when a high-temperature item is placed in the refrigerator 7 or when the evaporator 6 is pulled down after defrosting, the temperature inside the refrigerator becomes high, so the temperature sensor 12 inside the refrigerator detects the temperature. do.

If this internal temperature is higher than the temperature set by the low pressure pressure detector 9, the set pressure value of the low pressure pressure detector 9 is lowered by a predetermined value, and compared with the low pressure pressure, the frequency Instructs the frequency converter 11 to increase the output frequency, and increases the output frequency of the drive motor 1.
Increase the rotation of a. This speeds up the pulldown, lowers the low pressure force, and performs cooling operation. FIG. 2 is a graph showing the relationship between the internal temperature and the set pressure value in this case.

As described above, when the temperature inside the refrigerator becomes lower than the set value, the set pressure value of the low-pressure pressure detector 9 returns to the previously set pressure value due to the deviation value of the lower temperature, and the output frequency changes accordingly. The temperature inside the refrigerator reaches the target temperature by keeping the low pressure constant. In this manner, when the detected temperature is a deviation value lower than the set temperature, the pressure set value of the low pressure pressure detector 9 is set to the previous set value and is not lowered.

Note that when the load decreases, the low pressure force decreases and becomes below the set pressure value, so the output frequency is further reduced and the operation is performed so that the low pressure force becomes constant.

Furthermore, the amount by which the pressure setting value is lowered by a predetermined amount can be made linear in accordance with the deviation.

[Effect of idea]

Since the predetermined pressure setting value of the low pressure pressure detector is lowered by a predetermined amount based on the deviation value of the high temperature inside the refrigerator from the preset temperature value set in the low pressure pressure detector, the temperature inside the refrigerator is lowered by a predetermined amount. When the temperature is lower than the preset temperature value, energy-efficient cooling operation is performed.
When the temperature inside the refrigerator is higher than a preset temperature value, a cooling operation with good cooling rate performance for the objects to be cooled is performed. In particular, when the outside air temperature is low and the temperature of the objects to be cooled inside the refrigerator is high, such as in winter, the low outside air temperature condition lowers the refrigerant pressure in the entire refrigeration system, so the refrigerant returning to the compressor decreases. The pressure difference between the pressure and the predetermined pressure setting of the low-pressure pressure detector becomes smaller, which reduces the frequency of the electric power supplied to the drive motor of the compressor. acts to reduce the cooling rate of However, on the other hand, the high temperature state of the cooled object in the refrigerator is determined by the deviation value of the high temperature inside the refrigerator from the preset temperature value set in the low pressure pressure detector. Since the value is lowered by a predetermined amount, the pressure difference between the pressure of the refrigerant returning to the compressor and the predetermined pressure setting value of the low-pressure pressure sensor becomes large, which reduces the frequency of the power supplied to the drive motor of the compressor. This increase in frequency acts to increase the cooling rate of the objects to be cooled inside the refrigerator, and even if the outside temperature fluctuates, the cooling rate performance is always maintained and controlled according to the temperature inside the refrigerator, making it highly reliable. A refrigeration device is obtained.

[Brief explanation of the drawing]

Fig. 1 is a refrigerant circuit diagram of an embodiment of the refrigeration system of this invention, Fig. 2 is a graph showing the relationship between internal temperature and set pressure value to explain the operation of the above refrigeration system, and Fig. 3 is a graph showing the relationship between internal temperature and set pressure value. FIG. 2 is a refrigerant circuit diagram of a conventional refrigeration system. 1... Compressor, 1a... Drive motor, 3...
Condenser, 5... Expansion valve, 6... Evaporator, 7... Refrigerator, 9... Low pressure force detector, 11... Frequency converter, 12... Temperature sensor. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of utility model registration request] A compressor that compresses a refrigerant, a condenser that liquefies the refrigerant compressed by the compressor, an expansion valve that depressurizes and expands the refrigerant that has been liquefied in the condenser, and a refrigerant that has been depressurized and expanded by the expansion valve. an evaporator that evaporates a refrigerant through heat exchange with an object to be cooled in the refrigerator and returns the refrigerant to the compressor; a temperature sensor that detects a temperature in the refrigerator that cools the object to be cooled; and the compressor. A frequency converter that varies the frequency of the electric power supplied to the drive motor that drives the compressor detects the pressure of the refrigerant returning to the compressor, and compares the detected pressure with a predetermined pressure setting value to adjust the frequency. Determine the frequency of the converter and also
A low-pressure pressure detector that lowers the predetermined pressure set value by a predetermined amount based on a high temperature deviation value of the temperature detected by the temperature sensor from a preset set temperature value. Device.