JPS6129648A - 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 [Technical Field of the Invention] The present invention relates to a refrigeration system, and more particularly to an improvement in a refrigeration system that uses an inverter to control the rotation of a compressor.

[Prior art]

In recent years, with the rapid development of inverter technology, there is a tendency for inverters to be used in refrigeration equipment as well.

In this case, the refrigeration system having an inverter continuously changes the refrigeration capacity by controlling the rotation of the electric motor that drives the refrigerant compressor by varying the power supply frequency.

FIG. 1 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, and 2 is a high-pressure refrigerant discharged from the compressor 1, which is completely cooled and condensed. 3 is an expansion valve that rapidly expands the refrigerant supplied from the condenser 2; 4 is an evaporator that absorbs heat by evaporating the refrigerant expanded in the expansion valve 3; Its output side is connected to the compressor 1. 5
6 is an inverter that outputs a variable high-frequency power supply frequency; 6 is a control unit that controls the output frequency of the inverter according to the output signal level of a pressure detector 7 that detects the entire refrigerant pressure on the low-pressure side of the compressor 1; be. 8.9 is an electromagnetic contactor and an overcurrent relay connected in series in the middle of the power line connecting the inverter 5 and the compressor 1.

In the refrigeration system configured in this way, when the power switch (not shown) is fully turned on, the electromagnetic contactor 8 is closed and the electric power output from the inverter 5 is supplied to the electric motor (not shown) that drives the compressor 1. Then, the electric motor rotates the compressor 1 at a speed corresponding to the output frequency of the inverter 5. When the compressor 1 is driven, the compressed refrigerant is discharged and flows through the refrigeration cycle, and accordingly, cooling is performed by the evaporator 4 as is well known.

Here, when the cooling load decreases, the refrigerant pressure on the low pressure side of the refrigeration cycle decreases, so the output signal level output from the pressure detector T decreases accordingly. In the control section 6, the output frequency of the inverter 5 is controlled according to the difference between the output signal level of the pressure detector 7 and a reference value. If the output signal level of the pressure detector 7 is lower than the reference value, the control section 6 controls the inverter 5 to lower the output frequency. When the power supply frequency is lowered, the rotation of the electric motor (not shown) is lowered, so the rotation of the compressor 1 is lowered and the cooling capacity is lowered. 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. Furthermore, when the cooling load is high, the refrigerant pressure on the low pressure side of the refrigeration cycle increases, and accordingly, the pressure detection section 7
The output signal level output to the control unit 6 increases from then on.

As a result, the control unit 6 controls the inverter 5 to increase its output frequency, thereby increasing the rotational speed of the compressor 1 and increasing the cooling capacity.

Therefore, in a refrigeration system having an input/output unit configured in this way, the cooling capacity can be controlled in accordance with the cooling load, so that operation savings can be achieved.

However, in the refrigeration system having the above configuration, in order to operate the inverter 5 by continuously changing the output frequency of the inverter 5 at a constant frequency, for example, at IH2 intervals, at intervals of, for example, 5 seconds, the conduit A Resonance occurs at a portion that matches the natural frequency of the pipe A, which causes a crack in the pipe A, causing the refrigerant to be released into the atmosphere, making cooling impossible. In this case, since the natural frequency of pipe A differs depending on the refrigeration equipment, by operating the pipe so that it does not match the natural frequency of pipe A in any refrigeration equipment, it is possible to It is impossible to avoid the resonance state of .

In addition, a vibration isolator is provided to completely prevent the entire refrigeration system from vibrating due to the excitation force of the compressor, but when the output frequency of the inverter 5 is continuously changed,
Because there is an output frequency of the inverter that causes the entire refrigeration system to resonate, it is extremely difficult to manufacture a vibration isolator to prevent the vibration of the entire refrigeration system, and it also has the problem of requiring a large amount of cost. are doing.

[Summary of the invention]

In order to solve such problems, the present invention detects the refrigerant pressure on the low pressure side and controls the inverter to control the cooling capacity and converge the low pressure side refrigerant pressure to a predetermined value. A resonant operation prohibition circuit is provided for prohibiting operation of the compressor at an inverter output frequency where the output signal of the inverter exceeds a predetermined value.

In the refrigeration system configured in this manner, the resonant operation prohibition circuit operates while avoiding the resonant frequency of the refrigeration cycle, so that the refrigeration system can always operate in a normal state.

〔Example〕

FIG. 2 is a block diagram showing an embodiment of the refrigeration system according to the present invention, and the same parts as in FIG. 2 are indicated using the same symbols. In the figure, reference numeral 10 denotes a vibration detection unit fixed to the part of the pipe constituting the entire refrigeration cycle that is most likely to vibrate, for example, the pipe A connecting the compressor 1 and the condenser 2; Generates an output signal according to vibration. 11 is the control unit 6
and the inverter 5, which prohibits operation of the compressor 1 at an inverter output frequency where the vibration detection signal generated from the vibration detection unit 10 exceeds a predetermined value, for example, 5G. do.

The resonance operation prohibition section 11 is provided with a storage circuit that stores the inverter frequency once determined to be in a resonance state by the vibration detection section 10.

In the refrigeration system configured in this way, the vibration detection section 1
0 detects the vibration of the conduit A and the resonance operation prohibition section 11
supply its output signal to The resonance operation prohibition section 11 inputs the output signal of the vibration detection section 1o, thereby controlling the conduit A.
The region where the vibration is in a resonance state, for example, the vibration acceleration is 5G
When the frequency exceeds that level, it is determined that a resonance state exists, and the inverter 5 is controlled so as not to generate an output frequency in this region. The output frequency of the inverter 5, which has been determined even once to be a frequency at which this resonance state occurs, is stored in a memory circuit provided inside the resonance operation prohibition section 11, and is stored in a memory circuit provided inside the resonance operation prohibition section 11, and is used at a later time. The generation of the output from the inverter 5 is prohibited. Therefore, even in existing refrigeration equipment whose operating conditions and vibration systems are unknown, it is possible to operate the resonant frequency of pipe A, and the entire pipe does not become resonant due to a leak. This means that the vehicle can always be operated in a normal state. That is, if the cooling load is large during cooling operation and the compressor 1 needs to be operated at the output frequency of the inverter 5 at which the output of the vibration detection section 10 is determined to be in a resonant state, the control section 6 The rotation speed of the compressor 1 is controlled by increasing the inverter output frequency sound by, for example, IH2 every 5 seconds, and when it reaches the inverter output frequency range where resonance occurs, the resonance operation prohibition circuit 11 causes the frequency range to be exceeded. The compressor 1 is operated at the frequency, and then the rotation speed of the compressor 1 is sequentially increased to a predetermined frequency by the control unit 6. Furthermore, when the cooling load becomes small, the control is opposite to that described above.

Furthermore, when it is necessary to control the operation to an inverter frequency that causes resonance, and when the cooling load increases or decreases, the compressor 1 is operated at a frequency one step before the inverter output frequency that causes resonance.

Therefore, in the device configured in this manner, the entire pipe line will not be in a resonant state, thereby preventing the cooling operation from being stopped due to the occurrence of cracks in the pipe line.

In the above embodiment, the vibration detecting section 1° is connected to the conduit A.
Although the case where K is installed has been described, the present invention is not limited to this, and by installing it in the place where vibration is most likely to occur or the place where it is most likely to be damaged within the refrigeration equipment, it is possible to completely prevent vibration of the entire cooling equipment. [Effects of the Invention] As explained above, the refrigeration system according to the present invention detects the output frequency generated by the vibration detection section from among the output frequencies of the inverter. Since it is equipped with a resonance operation prohibition section that prohibits the compressor from operating at the inverter output frequency where the signal level exceeds a predetermined value, it is possible to operate the refrigeration cycle while avoiding the resonance frequency. Accordingly, cracks in the pipes, etc. are prevented and normal operation can be performed at all times.

Furthermore, since the refrigerating cycle can be operated while avoiding the resonant frequency, the vibration isolating device for the compressor can be made simple and inexpensive. Furthermore, when installing the refrigeration system, the installation frame can be made simple and inexpensive. Furthermore, since the vibration of the entire refrigeration system can be reduced, it has various excellent effects such as lower noise.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a conventional refrigeration system, and FIG. 2 is a block diagram showing an embodiment of a refrigeration system according to the present invention. 1-... Compressor, 2... Condenser, 4... Evaporator, 5
...Inverter, 6...Control unit, γ...Pressure detection unit, 8...-Magnetic contactor, 9...-Overcurrent relay, 10
--- Vibration detection section, 11... Resonance operation prohibition section. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] A refrigeration cycle configured by connecting a compressor, a condenser, an expansion valve, and an evaporator in a closed loop; an inverter that varies a power frequency and supplies it to an electric motor that drives the compressor; and the refrigeration cycle. a pressure detection unit that detects the refrigerant pressure on the low pressure side of the refrigeration system; a control unit that controls the inverter according to the output signal of the pressure detection unit to converge the refrigerant pressure on the low pressure side to a predetermined set value; a vibration detection unit that is attached to a part of the cycle to detect a vibration state, and the compressor at an inverter output frequency at which an output signal generated from the vibration detection unit is equal to or higher than a set value among the output frequencies of the inverter. A refrigeration system comprising: a resonance operation prohibition circuit that prohibits operation of the refrigeration system.