JPS63194161A - Refrigerator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a refrigeration system, and particularly relates to an improvement of a refrigeration system that uses an inverter to control the rotation of a compressor.

[Conventional technology]

A refrigeration system having an inverter controls the rotation of an electric motor that drives a refrigerant compressor by changing the power frequency. By controlling the rotational speed of the compressor in this way, the refrigerating capacity can be changed continuously.

FIG. 2 is a block diagram showing an example of a conventionally commonly used refrigeration system having an inverter, in which (1) is a compressor that compresses refrigerant, (2) is a condenser, and (3) is an expansion valve. , (4) are evaporators, which are connected in a closed loop via pipes to form a refrigeration cycle. (5) is commercial! (6) changes the output frequency of the inverter (5) according to the output signal of the pressure detection section (7) that detects the refrigerant pressure on the low pressure side of the compressor (1). This is a control unit that controls the (
8) is an electromagnetic contactor provided on the power supply fin connecting the inverter (5) and the compressor (1), and (9) is an overcurrent relay also provided in series with the power supply fin.

In this conventional refrigeration system configured as described above,
When M (not shown) is turned on, the magnetic contactor (
8) is closed, the electric power output from the inverter (5) is supplied to the electric motor (not shown) of the compressor (1), and the compressor (1) is operated.The compressor (1) is operated. As a result, when the compressed refrigerant reaches the refrigeration cycle μ, it is cooled by the evaporator (4) as is well known.

Here, when the refrigeration load decreases, the refrigerant pressure on the low pressure side of the refrigeration cycle μ decreases, and the pressure detector (7)
The level of the pressure detection signal outputted to the control unit (6) also decreases. The control unit (6) compares the pressure detection signal with the reference value, so if the pressure detection signal is lower than the reference value, the control unit (6) controls the inverter (5) so that the output frequency is reduced. The rotational speed of the compressor (1) is controlled to be lowered, thereby lowering the cooling capacity. When the cooling capacity is lowered in this way, the refrigerant pressure on the low-pressure side of the refrigeration cycle increases and converges to the set pressure.

First, when the cooling load is light, the refrigerant pressure on the low pressure side of the refrigeration cycle μ increases, and this causes the pressure detection part (7
) increases the pressure detection signal output from the controller (6). As a result, the control unit (6) controls the inverter (5) to increase its output frequency, and increases the rotational speed of the compressor (1), thereby increasing the cooling capacity.

Therefore, in a refrigeration system having such an inverter (5), the cooling capacity C is adjusted according to the cooling load.
ζ control is possible, and power saving is possible.

[Problem that the invention seeks to solve]

Since the conventional refrigeration system is configured as described above, the output frequency of the inverter (5) when restarting the compressor (1) after stopping is fixed at, for example, 40H2, and the output frequency of the inverter (5) is fixed at 40H2, for example. ) If the refrigerant pressure on the low pressure side of the refrigeration cycle increases during stoppage and the pressure detection signal becomes much higher than the reference value, it will take a long time to reach the target refrigerant pressure and the temperature of the cooled object will increase. However, there was a drawback that the freshness of the object to be cooled was not maintained. In addition, if the refrigerant pressure on the low pressure side of the refrigeration cycle increases when the compressor (1) is stopped, and the pressure detection signal is almost the same as the reference value, the refrigerant pressure on the low pressure side will suddenly decrease when restarting, causing the compression Machine (1) stopped,
There was a drawback that the interval between the start and stop of the compressor (υ) became shorter, and the life of the compressor (1) was shortened.

The present invention solves the above-mentioned conventional problems by detecting the refrigerant pressure on the low pressure side and converging the refrigerant pressure to a predetermined value. By controlling the inverter output frequency when restarting the compressor according to the pressure difference, the predetermined pressure can be quickly reached and power consumption can be reduced. The purpose is to provide equipment.

[Means to solve the problem]

The present invention includes a pressure detection unit that detects refrigerant pressure on the low pressure side of the refrigeration cycle and generates a pressure detection signal, and a pressure detection unit that converges the refrigerant pressure on the low pressure side to a predetermined set value in response to the pressure detection signal. - The frequency control section that sets the output frequency of the inverter and the pressure difference between the pressure detection signal and the refrigerant pressure to be converged, set the output frequency of the inverter when restarting the compressor after stopping. The above object is achieved by configuring a refrigeration system by providing a restart output frequency control section for controlling the restart output frequency.

[Effect]

In accordance with this invention, the refrigeration system detects the refrigerant pressure on the low pressure side and converges the refrigerant pressure to a predetermined value, and the pressure difference between the pressure detection signal and the refrigerant pressure to be converged. By controlling the inverter output frequency when restarting after a stop.

A predetermined pressure can be reached quickly, and the freshness of the object to be cooled is maintained.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of a refrigeration system according to the invention E, and the same parts as in FIG. 2 are indicated using the same symbols. In the figure, αQ is a frequency control section,
The inverter output frequency during the compressor operation is controlled according to the pressure difference between the pressure detection signal output from the pressure detection section (7) and the refrigerant pressure to be converged.

Further, (l) l is a restart output frequency control unit, which controls the compressor according to the pressure difference of 1 between the pressure detection signal outputted from the pressure detection unit (7) and the refrigerant pressure to be converged. It determines only the output frequency of the inverter when restarting after a stop. For example, if the pressure difference between the pressure detection signal output from the pressure detection part (7) and the refrigerant pressure to be converged is large, the inverter output when the compressor (1) is restarted after stopping. When the frequency is set to 75Hz and the pressure difference between the pressure detection signal output from the pressure detection section (7) and the refrigerant pressure to be converged is small, the compressor (
1) When restarting after stopping, set the inverter output frequency to 80
It can be set to H2.

Moreover, since the refrigerant pressure when the compressor (1) is stopped is constantly detected and compared with the refrigerant pressure to be converged, the refrigerant pressure is adjusted depending on the pressure difference when restarting the compressor (1) after stopping. For example, the inverter output frequency is 80Hz.

It can be changed from 31Hz to 15Hz.

However, if the refrigerant pressure when the compressor (1) is stopped becomes extremely high by one point higher than the reference value, the inverter (5) is operated at a higher frequency, so that the target refrigerant pressure is reached. The time required for cooling is shortened, and the freshness of the items to be cooled is maintained. In addition, when the refrigerant pressure at the time of stopping the compressor (υ) is almost the same as the reference value, the inverter (5) is operated at a lower frequency, so the refrigerant pressure on the low pressure side does not suddenly drop by 1, and the compressor (υ) The interval between starting and stopping of compressor (1) becomes longer, and the life of the compressor (1) also becomes longer.

〔Effect of the invention〕

As explained above, the refrigeration system according to the present invention includes a pressure detection section that detects the refrigerant pressure on the low pressure side of the refrigeration cycle and generates a pressure detection signal, and a pressure detection section that detects the refrigerant pressure on the low pressure side in accordance with the pressure detection signal. The frequency control section controls the output frequency of the inverter so that it converges to the set value of Since it is equipped with a restart output frequency control section that controls the output frequency of the inverter, the inverter output upon restart after the compressor is stopped is adjusted according to the pressure difference between the pressure detection signal and the refrigerant pressure to be converged. The frequency can be controlled, a predetermined pressure can be quickly reached, and the freshness of the object to be cooled can be maintained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a refrigeration system according to the present invention, and FIG. 2 is a block diagram showing a conventional refrigeration system. (1) is a compressor, (2) is a condenser, (3) is an expansion valve, (
4) is an evaporator, (5) is an inverter, (7) is a pressure detection section, CLG is a frequency control section, and aυ is a restart output frequency control section. In the drawings, the same reference numerals indicate corresponding parts.

Claims (1)

[Claims] A refrigeration cycle configured by a variable frequency inverter, a compressor driven by the output of this inverter, a condenser, an expansion valve, and an evaporator connected in a closed loop, and a refrigerant on the low pressure side of the refrigeration cycle. a pressure detection section that detects pressure and generates a pressure detection signal; a frequency control section that controls the output frequency of the inverter so that the refrigerant pressure on the low pressure side converges to a predetermined set value in accordance with the pressure detection signal; It is characterized by comprising a restart output frequency control section that controls the output frequency of the inverter when the compressor is restarted after stopping the compressor, according to the pressure difference between the pressure detection signal and the refrigerant pressure to be converged. refrigeration equipment.