JPH0570062B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an operation control device for a refrigeration system, and in particular, to a device for controlling the operation of a refrigeration system, and in particular to a system for controlling the operation of a refrigeration system in parallel with bypass control of a hot gas refrigerant so that the temperature inside the refrigerator converges to a desired temperature inside the refrigerator. This invention relates to improvements in capacity control for compressors.

(Prior Art) Conventionally, as an operation control device for this type of refrigeration equipment, a pole change type compressor, a condenser, an expansion mechanism, and an evaporator have been used, for example, as disclosed in Japanese Utility Model Publication No. 55-48359. They are connected in series in a closed circuit to form a circulating refrigerant circuit, and the discharge pipe and suction pipe of the compressor are connected through a bypass passage with a solenoid valve interposed in the middle. It is known that the internal temperature of the refrigerator is converged to a desired temperature by performing capacity control and bypass control of the hot gas refrigerant from the compressor by opening and closing a solenoid valve in parallel.

(Problem to be Solved by the Invention) However, in the above-mentioned conventional system, when the defrost operation is performed, the temperature inside the refrigerator becomes considerably higher than the desired temperature inside the refrigerator, so after the defrost operation is completed, the compressor It is necessary to quickly lower the temperature inside the refrigerator through high-capacity operation, but even when the temperature inside the refrigerator drops to around the desired temperature inside the refrigerator, the temperature inside the refrigerator is maintained at the desired temperature by bypass control of the hot gas refrigerant. Despite the temperature convergence, the compressor may continue to operate at high capacity. As a result, when the refrigeration load decreases, the amount of bypassed hot gas refrigerant that does not contribute to internal cooling increases, causing the compressor to essentially overoperate, resulting in an increase in reactive energy due to wasted refrigerant compression work. It was hot.

The present invention solves the problem of the compressor continuing to operate at a high capacity even after the defrost operation is finished and the internal temperature converges to the desired temperature, resulting in an increase in the bypass amount of hot gas refrigerant. The objective is to quickly bring the temperature inside the refrigerator to a desired temperature while saving energy by properly controlling the capacity of the compressor.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention includes a compressor 1, a condenser 2,
3. A circulating refrigerant circuit 7 formed by connecting the expansion mechanism 4 and the evaporator 5 in series in a closed circuit, and a bypass connected to the circulating refrigerant circuit 7 so as to bypass the condensers 2, 3 and the expansion mechanism 4. a passage 8, an adjusting means 9 for adjusting the bypass amount of the refrigerant flowing through the circulation refrigerant circuit 7 to the bypass passage 8, an internal temperature setter 12 for setting a desired internal temperature, and an internal temperature setting device 12 for detecting the internal temperature. Temperature sensor 13a or 13b,
The above-mentioned chamber temperature setting device 12 and temperature sensor 13a
or 13b, and a hot gas control means 14 which controls the adjustment means 9 so that the temperature inside the refrigerator reaches the desired temperature inside the refrigerator. The compressor 1 receives the outputs of the internal temperature setting device 12 and the temperature sensor 13a or 13b, and when the internal temperature is outside the limit temperature range set within a predetermined range with respect to the desired internal temperature, the compressor 1 While setting the capacity of the compressor 1 to a high capacity, when entering the above-mentioned limit temperature range, the capacity of the above-mentioned compressor 1 is initially set to the lowest stage, and then each time the internal temperature exceeds the above-mentioned limit temperature range and re-enters. A compressor capacity control means 15 that controls the capacity stages of the compressor 1 to gradually increase, receives the outputs of the chamber temperature setting device 12 and the temperature sensor 13a or 13b, and determines that the chamber temperature is set to the desired chamber temperature. A reset means 16 is provided for resetting the compressor capacity control means 15 to restart the capacity control of the compressor 1 from the beginning when the temperature becomes higher than a predetermined temperature.

(Function) With the above configuration, the present invention allows the compressor to After the capacity control means 15 initially changes the capacity of the compressor 1 from the high capacity stage to the lowest stage, the hot gas control means 14 adjusts the bypass amount of the hot gas refrigerant flowing through the circulation refrigerant circuit 7 to the bypass passage 8, i.e. Bypass control of the hot gas refrigerant allows the temperature inside the refrigerator to converge to the desired temperature inside the refrigerator.

However, when the refrigeration load is large, the internal temperature of the refrigerator does not converge to the desired internal temperature due to the capacity operation of the lowest stage of the compressor 1, and exceeds the above-mentioned limit temperature range. In that case, the temperature inside the refrigerator is brought back into the above-mentioned limit temperature range by operating the compressor at a high capacity. Then, when it re-enters the critical temperature range,
After the compressor capacity control means 15 increases the capacity of the compressor 1 by one stage, the internal temperature of the refrigerator is brought to a desired temperature by bypass control of the hot gas refrigerant. Nevertheless, when the temperature inside the refrigerator exceeds the above-mentioned limit temperature range again, the number of capacity stages of the compressor 1 is gradually increased each time it re-enters the limit temperature range in the same way as above, and then the hot gas Bypass control of the refrigerant is used to control the temperature inside the refrigerator to converge to the desired temperature inside the refrigerator.

During that time, when the temperature inside the refrigerator exceeds the above-mentioned limit temperature range and the compressor 1 is operated at high capacity, the temperature inside the refrigerator becomes higher than the desired temperature inside the refrigerator by a predetermined temperature or more due to defrost operation, etc. In this case, the reset means 16 resets the compressor capacity control means 15.
The control of the compressor 1 is reset to the initial state, and the capacity control of the compressor 1 is restarted from the beginning.

In this way, each time the temperature inside the refrigerator falls within the above-mentioned limit temperature range, the capacity of the compressor 1 is changed from the high capacity stage to the lowest stage, and then gradually increased, as described above, by bypass control of the hot gas refrigerant. Since the temperature inside the refrigerator is controlled to converge to the desired temperature inside the refrigerator, the control to converge the temperature inside the refrigerator to the desired temperature inside the refrigerator is appropriately performed at the low capacity stage of the compressor 1 as much as possible, and energy saving is achieved. As a result, even though the temperature inside the refrigerator has converged to the desired temperature inside the refrigerator, the compressor 1
This prevents the continuation of high capacity operation of the refrigerant and the accompanying increase in the bypass amount of hot gas refrigerant.

(Example) Hereinafter, an example of the present invention will be described based on the drawings from FIG. 2 onwards.

FIG. 2 shows an embodiment in which the present invention is applied to a refrigeration system A. In the figure, 1 is a compressor, 2 is a water-cooled condenser, 3 is an air-cooled condenser having three blower fans 3a that operate when cooling water is not circulating in the water-cooled condenser 2, and 4 is an expansion mechanism. The expansion valve 5 is an evaporator having two blower fans 5a, 5a. Each of the above devices 1 to 5 has a refrigerant pipe 6...
The circulating refrigerant circuit 7 is connected to allow refrigerant circulation.
By circulating the refrigerant through the compressor 1 through the air-cooled condenser 3, the water-cooled condenser 2, the expansion valve 4, and the evaporator 5 in order, the refrigerant is circulated through the compressor 1. In the evaporator 5, the amount of heat contained in the gas refrigerant is released to the outside of the refrigerator, and the amount of heat inside the refrigerator is absorbed by the liquid refrigerant in the evaporator 5, thereby cooling the interior of the refrigerator.

8 is a bypass passage connected to the circulating refrigerant circuit 7 so as to bypass the water-cooled and air-cooled condensers 2 and 3 and the expansion valve 4; 9 is a bypass passage connected to the circulating refrigerant circuit 7;
This is an electromagnetic three-way proportional valve serving as an adjusting means, which is interposed at the branching portion of the valve to the bypass passage 8. The three-way proportional valve 9 is configured to adjust the amount of refrigerant flowing through the circulating refrigerant circuit 7 that bypasses the bypass passage 8 .

The pressure equalization pipe of the expansion valve 4 communicates with the suction pipe when the set temperature is high (10°C or higher) during freezing and refrigeration operation, and communicates with the suction pipe when the set temperature is low (10°C or higher) during refrigeration operation. A three-way valve SV is provided which is switched to communicate with the bypass passage 8 when the temperature is low (higher than -10°C).

Further, 12 is an internal temperature setting device for setting a desired internal temperature, 13a is a temperature sensor that detects the outlet temperature as the internal temperature, and 13b is a temperature sensor that detects the suction temperature as the internal temperature. The internal temperature setting device 12 and temperature sensors 13a, 13b are each connected to the controller 10. The controller 10 is equipped with a hot gas control means 14 that outputs a control signal to the three-way proportional valve 9 so that the temperature inside the refrigerator becomes a desired temperature inside the refrigerator.

As a feature of the present invention, the controller 10 includes a CPU as shown in FIG.
21, RAM22, ROM23, I/O port 2
4, A/D converter 25 and drivers 26, 27
It receives the outputs of the internal temperature setting device 12 and the intake air temperature sensor 13b, and when the internal temperature is outside the limit temperature range set within a predetermined range with respect to the desired internal temperature, The above compressor 1
While setting the capacity of the compressor 1 to a high capacity, when entering the above-mentioned limit temperature range, the capacity of the above-mentioned compressor 1 is initially set to the lowest stage, and then each time the internal temperature exceeds the above-mentioned limit temperature range and re-enters. A compressor capacity control means 15 that controls the number of capacity stages of the compressor 1 to gradually increase, receives the outputs of the refrigerator temperature setting device 12 and the temperature sensor 13b, and determines that the refrigerator temperature is within the desired refrigerator temperature. A reset means 16 is configured to reset the capacity control of the compressor 1 by the compressor capacity control means 15 from the beginning when the temperature rises by a predetermined temperature, for example, by 5° C. or more.
Note that the above control may be performed using the output of the temperature sensor 13a on the blown air side instead of the temperature sensor 13b.

Further, the internal configuration of the controller 14 is shown in FIG. In the figure, MC is the compressor motor, MF ₁ is the blower fan motor of the evaporator 5,
MF ₂ is the blower fan motor of air-cooled condenser 3, 10
c is a compressor relay having a normally open contact 10C _-1 that operates the compressor motor MC and at the same time allows the blower fan motor MF ₂ of the air cooling condenser 3 to be energized; 10F is the blower fan motor of the evaporator 5;
The evaporator fan relay 20S1 having a normally open contact 10F _-1 for operating MF ₁ is a solenoid valve that is installed in the refrigerant pipe 6 and allows or blocks the flow of refrigerant in the circulating refrigerant circuit 7.

In Figures 2 and 3, 31 is a high pressure switch, 32 is a low pressure switch, 35 is an accumulator with heat exchanger, Tr is a transformer, S is a run/stop switch, and 37 is a hydraulic protection pressure. Switch, 38 is a lamp switch, 39 is a hydraulic reset switch, 4
0 is the compressor protection thermo. 42 to 45 are manual switching switches, all of which are interlocked.
2 is for voltage switching, 43 is for switching the connection of the transformer Tr,
44 and 45 are for compressor motor MC. Also,
60W is a water pressure switch that opens when cooling water is circulated to the water-cooled condenser 3, and stops the blower fan motor _MF2 of the air-cooled condenser 3 when the switch opens.

Next, the operation of the above embodiment will be explained based on FIG. 4.

When the compressor 1 is set to the highest stage and operated at high capacity (100%) in step (S ₁ ) when pulling down the refrigerator, the temperature inside the refrigerator decreases as shown in FIG. In step (S ₂ ), it is determined whether the temperature inside the refrigerator has entered a limit temperature range set with a predetermined width with respect to the desired temperature inside the refrigerator (SP). If the temperature inside the refrigerator is higher than the high limit temperature (point A in Figure 5), the high capacity (100%) operation of compressor 1 is continued, and the temperature is lower than the high limit temperature (point A), that is, within the limit temperature range. If it enters, step (S ₃ )
Proceed to.

In the above step (S ₃ ), under the control of the compressor capacity control means 15, the capacity of the compressor 1 is switched to the lowest stage to operate at a low capacity (33%). 13b), and in step (S ₄ ), the temperature inside the refrigerator reaches the PID control start temperature (SP+ based on the desired temperature inside the refrigerator (SP)).
It is determined whether the temperature has decreased to 1:0°C (point B on the top of FIG. 5) or lower. If the temperature inside the refrigerator is higher than the PID control start temperature (point B), it is determined in step (S ₅ ) whether or not the temperature inside the refrigerator is higher than the high limit temperature. Return to _{step 3} ) and continue operating the compressor 1 at a low capacity (33%), and if the temperature rises above the high limit temperature, proceed to step (S ₉ ).
Proceed to.

On the other hand, in the above step (S ₄ ), when the temperature inside the refrigerator falls below the PID control start temperature (point B),
In step (S ₆ ), PID control of the three-way proportional valve 9 is started. This PID control is performed by temperature sensor 1 on the blowing air side.
Done in 3a. Next, in step (S ₇ ), it is determined whether the temperature inside the refrigerator has risen beyond the above-mentioned limit temperature range, that is, the high limit temperature (point C in FIG. 5). If the temperature inside the refrigerator is below the high limit temperature (point C), PID control continues, and if it becomes higher than the high limit temperature (point C), step ( _S8 ) is performed.
The PID control of the three-way proportional valve 9 is stopped at step _S9 .

Then, in the above step (S ₉ ), the compressor 1 is operated at a high capacity (100%), and in this state, in step (S ₁₀ ), the temperature inside the refrigerator is set to a predetermined temperature (for example, 50%) relative to the desired inside temperature. It is determined whether or not the temperature has risen above ℃). If the temperature inside the refrigerator is less than the predetermined temperature, the process proceeds to step (S ₁₁ ), while if it becomes higher than the predetermined temperature, the process returns to step (S ₁ ) and the compressor capacity control means 15 is initially controlled. Set the status again. Further, in step (S ₁₁ ), it is determined whether the temperature inside the refrigerator has fallen below the high limit temperature (point D in FIG. 5). If the temperature inside the refrigerator does not fall below the high limit temperature, the process returns to step (S ₃ ) and the high capacity (100%) operation of the compressor ₁ continues; ).

Then, in step (S ₁₂ ), the compressor 1 is switched to medium capacity (67%) operation, and in this state, in steps (S ₁₃ ) to (S ₁₈ ), the above steps (S ₄ ) to
The same control as in (S ₉ ) is performed and the process advances to step (S ₁₉ ).

Then, in the above step (S ₁₉ ), similarly to the above step (S ₁₉ ), it is determined whether or not the internal temperature of the refrigerator has become higher than the desired internal temperature by a predetermined temperature (for example, 5°C), and the predetermined temperature is If it becomes higher than that, the process returns to step (S ₁ ) and the control of the compressor capacity control means 15 is reset to the initial state and the control is restarted. On the other hand, if the internal temperature is lower than the desired internal temperature, step (S ₂₀ ) is performed.
Wait for the temperature inside the refrigerator to drop below the PID control start temperature, and then turn on the PID of the three-way proportional valve 9 in step ( _S21 ).
Control is restarted and the temperature inside the refrigerator is brought to the desired temperature.

Therefore, in the above embodiment, when the temperature inside the refrigerator enters the limit temperature range, the capacity of the compressor 1 is set to the lowest stage, and thereafter, every time the temperature inside the refrigerator exceeds the limit temperature range and re-enters, the compressor 1 is set to the lowest stage. In addition to increasing the capacity stage of the compressor, if the temperature inside the refrigerator rises by a predetermined temperature (for example, 5 degrees Celsius) or more higher than the desired temperature inside the refrigerator, such as during defrost operation, the compressor capacity control means The capacity control of the compressor by No. 15 was restarted from the initial state. This results in
Compressor 1 controls the temperature inside the refrigerator to converge to the desired temperature inside the refrigerator.
The compressor 1 can be operated at an appropriate capacity stage as low as possible according to the refrigeration load of the compressor 1. (100%) continuation of operation can be prevented, and the work of compressing refrigerant due to excessive operation of the compressor 1 can be suppressed to the lowest possible level, resulting in energy savings.

Furthermore, when the refrigerator is pulled up, the compressor 1 is set to the highest stage and a high capacity (100%) heating operation is performed to raise the temperature inside the refrigerator and bring it within the limit temperature range. Thereafter, the same control as in the pull-down process (steps (S ₂ ) to (S ₂₁ ) in FIG. 4) may be performed, and the same actions and effects as in the pull-down process can be achieved.

Although the compressor capacity may be controlled by the temperature sensors 13b and 13a on either the suction side or the outlet side, it is preferable to use the temperature sensor 13b on the suction side from the viewpoint of preventing air temperature hunting.

Further, in the above embodiment, the three-way proportional valve 9 was used as the adjustment means, but an electromagnetic two-way valve is provided in the circulating refrigerant circuit 7 and the bypass passage 8 downstream of the branching part with the bypass passage 8, respectively. Good too,
The same actions and effects as in the above embodiment can be achieved.

(Effects of the Invention) As described above, in the present invention, when the temperature inside the refrigerator falls within the limit temperature range set with a predetermined width with respect to the desired temperature inside the refrigerator, the compressor operating at high capacity The capacity is set to the lowest stage, and each time the internal temperature exceeds the above-mentioned limit temperature range and re-enters, the capacity stage of the compressor is gradually increased, and the internal temperature reaches a predetermined temperature (for example, If the temperature rises above 5°C, the compressor capacity control by the compressor capacity control means is restarted from the beginning, so if the internal temperature becomes considerably higher than the desired internal temperature due to defrost operation, etc. In this case, convergence control to the desired warehouse temperature is appropriately performed with the lowest possible capacity of the compressor depending on the refrigeration load, and over-operation can be prevented by operating the compressor at the lowest possible capacity stage. As a result, wasteful refrigerant compression work, such as continuing high-capacity operation of the compressor even though the internal temperature of the refrigerator has converged to the desired internal temperature, can be suppressed and energy can be saved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention. 2 to 5 show embodiments of the present invention, FIG. 2 is a refrigerant piping system diagram of a refrigeration system, FIG. 3 is an electric circuit diagram, and FIG. 4 is a flow chart showing the basic operation of the controller. FIG. 5 is a diagram showing temporal changes in the temperature inside the refrigerator during operation of the refrigeration system. A... Refrigeration device, 1... Compressor, 2... Water-cooled condenser, 3... Air cooling condenser, 4... Expansion valve, 5...
Evaporator, 7... Circulating refrigerant circuit, 9... Three-way proportional valve, 12... Internal temperature setting device, 13a, 13b...
...Temperature sensor, 14...Hot gas control means, 1
5... Compressor capacity control means, 16... Reset means.

Claims (1)

[Claims] 1 A circulating refrigerant circuit 7 in which a compressor 1, condensers 2, 3, an expansion mechanism 4, and an evaporator 5 are connected in series in a closed circuit, and the above-mentioned condensers 2, 3 are connected to the circulating refrigerant circuit 7.
and a bypass passage 8 connected to bypass the expansion mechanism 4, an adjusting means 9 for adjusting the bypass amount of the refrigerant flowing through the circulation refrigerant circuit 7 to the bypass passage 8, and a chamber for setting a desired chamber temperature. An internal temperature setting device 12, a temperature sensor 13a or 13b that detects the internal temperature, and the internal temperature setting device 1
2 and the output of the temperature sensor 13a or 13b, hot gas control means 14 controls the adjustment means 9 so that the temperature inside the refrigerator reaches the desired temperature inside the refrigerator.
In an operation control device for a refrigeration system, the refrigerator temperature is set to have a predetermined range with respect to the desired refrigerator temperature in response to the outputs of the refrigerator temperature setting device 12 and the temperature sensor 13a or 13b. When the temperature is outside the limit temperature range, the capacity of the compressor 1 is set to a high capacity, while when the temperature falls within the limit temperature range, the capacity of the compressor 1 is initially set to the lowest stage, and then the internal temperature is set to the above limit. Compressor capacity control means 15 controls the capacity stage of the compressor 1 to be gradually increased each time the compressor 1 reenters the temperature range, and receives the outputs of the internal temperature setting device 12 and the temperature sensor 13a or 13b. and reset means 16 for resetting the capacity control of the compressor 1 by the compressor capacity control means 15 from the beginning when the temperature inside the refrigerator becomes higher than the desired temperature inside the refrigerator by a predetermined temperature or more. An operation control device for a refrigeration system, characterized in that: