JPH0833242B2 - Refrigeration equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a refrigerating device such as an air conditioner, a chiller, a refrigerator, or the like.

(Prior Art) An example of a refrigerant circuit of a conventional air conditioner is shown in FIG. 6, in which a refrigerant gas discharged from a compressor 1 is cooled by a condenser 2 to be condensed and liquefied, and then an electronic expansion is performed. It is decompressed by the valve 3 and adiabatically expanded. Then, the evaporator 4 evaporates and vaporizes by absorbing heat from the air in the chamber flowing through the evaporator 4 and returns to the compressor 1.

The refrigerant temperature at the outlet of the evaporator 4 is the refrigerant temperature detector 5
The refrigerant pressure at the outlet of the evaporator 4 is detected by the refrigerant pressure detector 6, and the opening of the electronic expansion valve 3 is controlled by the output of the control device 7 which receives signals from these detectors 5 and 6. , The flow rate of the refrigerant passing through this is adjusted.

Thus, the refrigerant temperature at the outlet of the evaporator 4 is about 5d below the saturation temperature corresponding to the refrigerant pressure at the outlet of the evaporator 4.
For example, it is overheated and the full capacity of the evaporator 4 is exerted.

When operating this refrigerating apparatus with a partial refrigerating capacity equal to or lower than the refrigerating capacity, that is, during the refrigerating capacity control operation, the compressor 1
The refrigerant gas discharged from the condenser 2 and the electronic expansion valve 3
Via the bypass circuit 10 and the electronic control valve 11 for bypassing the refrigerant.

The temperature of the air blown through the evaporator 4 is measured by the air temperature detector 8
This signal is input to the controller 7 and the difference between the set temperatures set by the temperature setter 9 is calculated.
Then, the electronic control valve 11 is controlled by the output from the control device 7, and the amount of the refrigerant passing through the electronic control valve 11 is adjusted so that the blown air temperature becomes the set temperature.

(Problems to be Solved by the Invention) In the conventional refrigeration system described above, the electronic expansion valve 3 is provided so that the evaporator 4 exhibits its maximum refrigeration capacity even during the refrigeration capacity control operation. The refrigerant flow rate is adjusted, and the refrigerating capacity is reduced by combining the high-temperature and high-pressure refrigerant gas that has passed through the electronic control valve 11 with the refrigerant that has flowed out of the electronic expansion valve 3, thus reducing the compressor capacity. There is a problem in that the amount of refrigerant circulating through 1 hardly decreases, and therefore, the power consumption of the compressor 1 hardly changes despite the small refrigerating capacity. Further, since the bypass circuit 10 and the electronic control valve 11 for the refrigerating capacity control operation are required, there is a problem that the refrigerant circuit becomes complicated and the cost and installation space for this are increased.

(Means for Solving Problems) The present invention was invented to address the above problems, and the gist of the present invention is to provide a compressor, a condenser,
In the refrigeration system in which the refrigerant circulates through the electronic expansion valve and the evaporator in this order, a detector for detecting the refrigerant temperature and pressure at the outlet of the evaporator and the temperature of the medium to be cooled is provided, and the temperature of the medium to be cooled is predetermined. When the upper limit temperature T _H or higher, the opening degree of the electronic expansion valve is maximized so that the refrigerant superheat degree calculated based on the outlet refrigerant temperature and pressure of the evaporator becomes a predetermined refrigerant superheat degree, and the medium to be cooled is cooled. When the temperature is equal to or lower than the predetermined lower limit temperature T _{L, the} compressor is stopped, and when the temperature of the medium to be cooled is between the upper limit temperature T _H and the lower limit temperature T _L , the opening degree of the electronic expansion valve is changed. Smaller than the maximum opening, and
A refrigeration apparatus is provided with a control device for controlling an opening degree corresponding to a temperature difference between a temperature of a medium to be cooled and a set temperature T _S.

(Operation) Since the present invention has the above configuration, when the temperature of the medium to be cooled is equal to or higher than the predetermined upper limit temperature T _H, the refrigerant superheat degree calculated based on the outlet refrigerant temperature and pressure of the evaporator is the predetermined refrigerant. The degree of opening of the electronic expansion valve is maximized so that the superheat degree is reached, the compressor is stopped when the temperature of the medium to be cooled is equal to or lower than the predetermined lower limit temperature T _L, and the temperature of the medium to be cooled is set to the upper limit temperature T _H and the lower limit temperature T _L. When it is between _L and _L , the degree of opening of the electronic expansion valve is controlled to be smaller than the above-mentioned maximum degree of opening and corresponding to the temperature difference between the temperature of the medium to be cooled and the set temperature T _S.

(Embodiment) An embodiment of the present invention will be specifically described with reference to FIGS.

FIG. 1 is a refrigerant circuit diagram, in which 1 is a compressor, 2 is a condenser, 3 is an electronic expansion valve, 4 is an evaporator, 5 is a refrigerant temperature detector, 6 is a refrigerant pressure detector, and 8 is a refrigerant pressure detector. Blown air temperature detector,
Reference numeral 9 is a temperature setting device, and the above is the same as the conventional one shown in FIG.

An intake air temperature detector 12 for detecting the temperature of the air sucked into the evaporator 4 is provided. Then, signals from the refrigerant temperature detector 5, the refrigerant pressure detector 6, the blown air temperature detector 8, the intake air temperature detector 12 and the temperature setting device 9 are input to the control device 21, and the control device 21 outputs signals. The output controls the electronic expansion valve 3 and the compressor 1.

A functional block diagram of the control device 21 is shown in FIG. 2, and its flowchart is shown in FIG.

In FIG. 3, the blown air temperature detector 8 is stepwise.
From the intake air temperature detector 12 or the intake air temperature from the intake air temperature detector 12 is input to the temperature difference calculation circuit 211 of the control device 21, and the set temperature from the temperature setter 9 is input to the temperature difference calculation circuit 211 in step. It Next, at step, the temperature difference calculation circuit 211 calculates the temperature difference between the blown air temperature or the intake air temperature and the set temperature. Then, in step, it is determined whether or not the refrigerating capacity is appropriate, and if it is determined to be appropriate, the process returns to step, but if it is determined to be excessive, in step the valve opening output command circuit 212 is passed. An output signal for reducing the opening is output to the electronic expansion valve 3. If it is judged to be too small, an output signal for increasing the opening is output to the electronic expansion valve 3 through the valve opening output command circuit 212 in step. Then, the fourth
As shown in the figure, the maximum refrigerating capacity Q ₁ is exhibited at the expansion valve opening A, and the refrigerating capacity Q ₂ is reduced at an expansion valve opening less than this, for example, B. When the expansion valve opening becomes A or more, a part of the refrigerant returns to the compressor 1 as a liquid and the compressor 1 is damaged, so that the expansion valve opening does not become larger than A.

Then, as shown in FIG. 5, when the blown air temperature or the sucked air temperature is equal to or higher than the temperature T _H , the maximum capacity operation is performed, and the control device 21 controls the evaporator 4 detected by the refrigerant temperature detector 5. The refrigerant temperature at the outlet of the refrigerant is about 5 degrees below the saturation temperature corresponding to the refrigerant pressure at the outlet of the evaporator 4 detected by the refrigerant pressure detector 6.
The opening of the electronic expansion valve 3 is controlled so that it is overheated.
When the blown air temperature or the sucked air temperature is equal to or lower than the temperature T _L , the control device 21 outputs it to the compressor 1 and stops it. Then, the refrigerating capacity control operation is performed between the temperatures T _H and T _L , that is, within a range of several degrees above and below the set temperature T _s , and the outlet air temperature or the intake air temperature gradually converges to the set temperature T _s .

As a result, during the refrigerating capacity control operation, the opening degree of the electronic expansion valve 3 is made smaller than that at the maximum capacity so as to correspond to the refrigerating load, and therefore, the amount of refrigerant circulating through the electronic expansion valve 3 is reduced. The power consumption of the compressor 1 is also reduced. that's all,
Although the example in which the present invention is applied to an air conditioner has been described,
The cooled medium cooled by the evaporator 4 may be liquid or solid.

(Effect of the Invention) In the present invention, the temperature of the medium to be cooled is the predetermined upper limit temperature.
When T _H or higher, the maximum refrigerating capacity is achieved by maximizing the opening degree of the electronic expansion valve so that the refrigerant superheat degree calculated based on the evaporator outlet refrigerant temperature and pressure becomes the predetermined refrigerant superheat degree. Therefore, the temperature of the medium to be cooled can be quickly brought close to the set temperature T _s .

Further, since the opening degree of the electronic expansion valve does not exceed the maximum opening degree, it is possible to prevent the compressor from being damaged due to the liquid refrigerant returning to the compressor.

Further, when the temperature of the medium to be cooled is equal to or lower than the predetermined lower limit temperature T _L , the compressor is stopped, so that the power consumption of the compressor can be saved.

Further, when the cooled medium temperature is between the upper limit temperature T _H and the lower limit temperature T _L , the opening degree of the electronic expansion valve is smaller than the maximum opening degree, and the cooled medium temperature and the set temperature T _s The refrigerating capacity can be reduced from the maximum capacity by controlling the opening degree corresponding to the temperature difference of.

Therefore, since the refrigerant circulation amount during the refrigerating capacity control operation is smaller than that during the maximum capacity operation, the power consumption of the compressor is also reduced.

Further, since the conventional bypass circuit and the electronic adjusting valve for opening and closing the bypass circuit can be omitted, not only the refrigerant circuit can be simplified, but also the cost and the installation space can be saved.

[Brief description of drawings]

1 to 5 show one embodiment of the present invention, FIG. 1 is a refrigerant circuit diagram, FIG. 2 is a functional block diagram of a control device, FIG. 3 is a flow chart of the control device, and FIG. FIG. 5 is a diagram showing the relationship between the valve opening and the refrigerating capacity, and FIG. 5 is a diagram showing the relationship between the temperature of the medium to be cooled and the operating mode. FIG. 6 is a refrigerant circuit diagram of a conventional refrigeration system. Compressor …… 1, condenser …… 2, electronic expansion valve …… 3, evaporator …… 4, control unit …… 21, refrigerant temperature detector …… 5,
Refrigerant pressure detector …… 6, Cooled medium temperature detector …… 8,
12, temperature setting device ... 9

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Toshio Yamashita Toshio Yamashita 3-1, Asahi-cho, Nishibiwajima-cho, Nishi-Kasugai-gun, Aichi Prefecture Mitsubishi Heavy Industries, Ltd. Nagoya Cold Energy Plant (72) Inventor Kan, Nakamura, Naka City, Aichi Prefecture No. 1 Takamichi, Iwatsuka-cho, Ward, Nagoya Research Institute, Mitsubishi Heavy Industries, Ltd. (56) Reference JP-A-60-196569 (JP, A) JP-A-60-185075 (JP, A)

Claims (1)

[Claims] 1. A refrigeration system in which a refrigerant circulates through a compressor, a condenser, an electronic expansion valve and an evaporator in this order, and a detector for detecting the refrigerant temperature and pressure at the outlet of the evaporator and the temperature of a medium to be cooled. When the temperature of the medium to be cooled is equal to or higher than a predetermined upper limit temperature T _{H, the} electronic expansion is performed so that the refrigerant superheat degree calculated based on the outlet refrigerant temperature and pressure of the evaporator becomes the predetermined refrigerant superheat degree. Maximum valve opening,
When the cooled medium temperature is equal to or lower than a predetermined lower limit temperature T _{L, the} compressor is stopped, and when the cooled medium temperature is between the upper limit temperature T _H and the lower limit temperature T _L , the electronic expansion valve A refrigeration system provided with a control device for controlling the opening to be smaller than the maximum opening and controlling the opening to correspond to the temperature difference between the temperature of the medium to be cooled and the set temperature T _S.