JPH0570063B2 - - 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 control 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 by 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.

(Problems to be Solved by the Invention) In a refrigerated container, the desired internal temperature varies depending on the type of items stored in the container. usually,
When the desired internal temperature of the refrigerator is high, the amount of ventilation inside the refrigerator tends to increase, and the outside air load due to this ventilation increases, and accordingly, the refrigeration load also becomes larger than when the desired internal temperature of the refrigerator is low. Tend.
Conversely, when the desired refrigerator internal temperature is low, the refrigeration load tends to be smaller when the outside air load is included, compared to when it is high.

However, with the conventional system described above, regardless of the type of items stored in the refrigerator, that is, the size of the refrigeration load including the outside air load, the compressor can be operated at high capacity by only bypassing the hot gas refrigerant from the compressor. The temperature inside the refrigerator is always brought to a desired temperature. Therefore, even when the refrigeration load is low, the compressor continues to operate at high capacity without being unloaded, and a large amount of refrigerant is bypassed without contributing to internal cooling, resulting in wasted refrigerant compression work. There was a problem that the energy consumption increased and went against energy conservation.

The present invention has been made in view of the above points, and its purpose is to save energy by properly controlling the capacity of the compressor according to the desired temperature inside the refrigerator, which is determined by the type of stored items. The objective is to quickly converge the temperature inside the refrigerator to the desired temperature in the refrigerator.

(Means for Solving the Problem) 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 passage connected to the circulating refrigerant circuit 7 so as to bypass the condensers 2 and 3 and the expansion mechanism 4. 8, and the bypass passage 8 for the refrigerant flowing through the circulating refrigerant circuit 7.
an adjustment means 9 for adjusting the amount of bypass to the refrigerator; an interior temperature setting device 12 for setting a desired interior temperature according to the type of stored items; a temperature sensor 13a or 13b for detecting the interior temperature; Internal temperature setting device 12
and a hot gas control means 14 which receives the output of the temperature sensor 13a or 13b and controls the adjustment means 9 so that the temperature inside the refrigerator reaches the desired temperature inside the refrigerator.
This assumes an operation control device for a refrigeration system equipped with the following. The compressor 1 receives the outputs of the temperature setting device 12 and the temperature sensor 13a or 13b, and when the temperature inside the refrigerator is outside the limit temperature range set within a predetermined range with respect to the desired temperature inside the refrigerator, 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 every time the internal temperature exceeds the above-mentioned limit temperature range and re-enters the above-mentioned limit temperature range. The compressor capacity control means 15 receives the output of the compressor capacity control means 15 which controls the capacity stages of the compressor 1 to gradually increase, and the chamber temperature setting device 12, and the compressor capacity control means 15 controls the compressor capacity control means 15 according to the desired chamber temperature. The apparatus further includes changing means 16 for changing the number of stages to be increased from the lowest stage of the capacity of the compressor 1 when entering the limit temperature range.

(Function) With the above configuration, in the present invention, the desired warehouse temperature is set by the warehouse temperature setter 12 according to the type of stored items in the warehouse, and the compressor capacity control means 15 is set based on the desired warehouse temperature. The mode for increasing the number of stages from the lowest stage of the compressor 1 capacity when entering the limit temperature range is changed.

Based on the mode of increasing the number of stages, when the temperature inside the refrigerator enters the limit temperature range set within a predetermined range with respect to the desired temperature inside the refrigerator, the capacity of the compressor 1 is initially increased from the high capacity stage to the lowest stage. After the refrigerant is heated, the temperature inside the refrigerator is made to converge to the desired temperature by adjusting the bypass amount of the hot gas refrigerant flowing through the circulating refrigerant circuit 7 to the bypass passage 8, that is, by controlling the bypass of the hot gas refrigerant.

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 compressor 1 is operated at a high capacity to bring the temperature inside the refrigerator into the above-mentioned limit temperature range again. Thereafter, each time the temperature re-enters the limit temperature range, the capacity stage of the compressor 1 is gradually increased by the compressor capacity control means 15, and then the internal temperature of the refrigerator is brought to the desired internal temperature by bypass control of the hot gas refrigerant. Let it converge.

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 in the refrigerator is controlled to converge to the desired temperature in the refrigerator, the control to converge the temperature in the refrigerator to the desired temperature in the refrigerator is performed as much as possible at the low capacity stage of the compressor 1, thereby saving energy. As a result, it is possible to prevent the continuation of high capacity operation of the compressor 1 even though the temperature inside the refrigerator has converged to the desired temperature inside the refrigerator, as in the past, and to prevent the amount of bypass of the hot gas refrigerant from increasing accordingly. .

In addition, the number of stages for increasing the capacity of the compressor when entering the above-mentioned limit temperature range is changed according to the desired temperature inside the refrigerator, which is determined by the type of items stored in the refrigerator, so the outside air load due to ventilation is large and the refrigeration load is large. If the desired temperature inside the refrigerator, which tends to increase The compressor 1 can be operated at the lowest possible capacity stage and at the optimum capacity stage depending on the temperature, resulting in further energy savings.

(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, and 3 is three blower fans 3a, 3a, .
4 is an expansion valve as an expansion mechanism, and 5 is an evaporator having two blowing fans 5a, 5a. Each of the above-mentioned devices 1 to 5 is connected to allow refrigerant circulation through refrigerant piping 6, . valve 4
By circulating the gas refrigerant through the evaporator 5 and the compressor 1, the water-cooled or air-cooled condensers 2 and 3 release the heat contained in the gas refrigerant to the outside of the refrigerator, and the evaporator 5 transfers the heat in the refrigerator to the liquid refrigerant. It is designed to cool the inside of the refrigerator by absorbing it.

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).

Furthermore, reference numeral 12 denotes an internal temperature setting device for setting a desired internal temperature according to the type of stored items; 13a a temperature sensor that detects the outlet temperature as the internal temperature;
3b is a temperature sensor that detects the suction temperature as the temperature inside the refrigerator. The internal temperature setting device 12 and temperature sensors 13a and 13b are each connected to the controller 1.
Connected to 0. The controller 10 includes:
A hot gas control means 14 is provided for outputting a control signal to the three-way proportional valve 9 so that the temperature inside the refrigerator reaches a desired temperature.

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 the internal temperature falls within a limit temperature range (desired internal temperature) set within a predetermined width relative to the desired internal temperature. When the temperature is outside the temperature range between the high limit temperature (+2.5℃) and the low limit temperature (-1.5℃) based on the internal temperature (SP), the capacity of compressor 1 is set to high capacity (100%). ), while
When the temperature reaches the above-mentioned limit temperature range, the capacity of the compressor 1 is initially set to the lowest stage, and then the capacity stage of the compressor 1 is gradually increased each time the temperature inside the refrigerator exceeds the above-mentioned limit temperature range and re-enters the range. The compressor capacity control means 15 receives the output of the internal temperature setting device 12 and controls the compressor capacity control means 15 to control the internal temperature according to the desired internal temperature determined by the type of stored items. A changing means 16 is configured to change the mode of the number of stages to be increased from the above-mentioned lowest stage of the capacity of the compressor 1 when entering the limit temperature range.
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.

The above desired temperature inside the refrigerator varies depending on the type of food stored in the refrigerator, for example, 13℃ for bananas, 0.5℃ for kiwi and asparagus, and 5℃ for oranges.
and each one is different. The optimal capacity stage of the compressor 1 is determined as shown in FIG. 6 for the outside air condition depending on the type of stored items in each warehouse. According to FIG. 6, for example, in the case of bananas, which have a high desired internal temperature, the amount of ventilation will be large, and the outside air load due to this ventilation will be large, and the refrigeration load will also tend to be large. The number of stages is 33%, 67%, and 100%, whereas in the case of kiwi fruit or oranges, which have a low desired internal temperature, ventilation is hardly required, and the refrigeration load can be reduced accordingly. , 33%, and 67%.

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-cooled condenser 3 to be energized; 10F is the blower fan motor MF of the evaporator 5; ₁
The evaporator fan relay 20S1 having a normally open contact 10F _-1 for operating the evaporator fan relay 20S1 is a solenoid valve that is installed in the refrigerant pipe 6 to allow or block the flow of refrigerant in the closed 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.

First, in step (S ₁ ), based on the desired refrigerator temperature set by the refrigerator temperature setting device 10, it is determined whether the desired refrigerator temperature is equal to or higher than the switching temperature (10° C.). If the desired temperature inside the refrigerator is 10°C or higher, flag F is set to "0" in step (S ₂ ), and if it is less than 10°C, the flag F is set to "0" in step (S ₃ ).
Set flag F to "1".

Then, in step (S ₄ ), when the compressor 1 is operated at a high capacity (100%) at the highest stage, the temperature inside the refrigerator decreases as shown in FIG. In (S ₅ ), it is determined whether the temperature inside the refrigerator has fallen below the high limit temperature (point A in Figure 5). The temperature inside the refrigerator is at the high limit temperature (A
point), the high capacity of compressor 1 (100
%) operation continues, and if the temperature drops below the high limit temperature (point A), proceed to step (S ₆ ).

In the above step (S ₆ ), the capacity of the compressor 1 is set to the lowest stage to perform low capacity (33%) operation, and in step (S ₇ ), the temperature inside the refrigerator reaches the PID control start temperature (desired temperature inside the refrigerator (SP ) +1.0℃:
It is determined whether or not the temperature has decreased to point B in the upper part of FIG. If the temperature inside the refrigerator is higher than the PID control start temperature (point B), it is determined in step ( _S8 ) whether or not the temperature inside the refrigerator is higher than the high limit temperature, and if it is below the high limit temperature, step Returning to step (S ₆ ), the compressor 1 continues to operate at a low capacity (33%), and if the temperature rises above the high limit temperature (point C in FIG. 5), proceed to step (S ₁₂ ).

On the other hand, in the above step (S ₇ ), if the temperature inside the refrigerator falls below the PID control start temperature (point B), the process proceeds to step (S ₉ ), and the three-way proportional valve 9 is opened.
Start PID control. (This control is performed by the temperature sensor 13a on the blowing air side). After that, in step (S ₁₀ ), it is determined whether the temperature inside the refrigerator has risen above the high limit temperature (C point), and the high limit temperature (C point) is determined.
point), the PID control of the three-way proportional valve 9 is continued, and if the temperature rises above the high limit temperature (point C), the PID control of the three-way proportional valve 9 is continued in step ( _S11 ).
Control is stopped and the process proceeds to step ( _S12 ).

Furthermore, in the above step (S ₁₂ ), the capacity of the compressor 1 is set to the highest stage and high capacity (100%) operation is performed, and the process proceeds to step (S ₁₃ ). At this step (S ₁₃ ), the temperature inside the refrigerator reaches the high limit temperature (point D in Figure 5).
It is determined whether the temperature has dropped below the high limit temperature (point D), and if it is higher than the high limit temperature (point D), high capacity (100%) operation of compressor 1 is continued, and if the temperature has dropped below the high limit temperature (point D). In step (S ₁₄ ), the capacity of the compressor 1 is set to an intermediate stage to perform medium capacity (67%) operation, and the process proceeds to step (S ₁₅ ).

Then, in the above step (S ₁₅ ), the flag F is set to 1" is determined. If the flag F is "1", the process directly proceeds to step ( _S22 ), while if the flag F is not 1, the above steps ( _S7 ) to ( _S7 ) are performed in steps (S16) to ( _S21 ).
After performing the same control as in step (S ₁₂ ) and operating the compressor 1 at the highest capacity (100%), the process proceeds to step (S ₂₂ ).

As a result, the temperature inside the refrigerator will increase in step (S ₂₂ ).
Wait for the temperature to drop below the PID control start temperature.
In step (S ₂₃ ), the PID control of the three-way proportional valve 9 is restarted, and the temperature inside the refrigerator converges to the desired temperature inside the refrigerator.

Therefore, in the above embodiment, the capacity of the compressor 1 is gradually increased from the lowest stage every time the temperature inside the refrigerator reaches the limit temperature range, so that the temperature inside the refrigerator converges to the desired temperature inside the refrigerator. Since this convergence control to the desired chamber temperature can be performed by operating the compressor 1 at the lowest possible capacity stage, it is possible to reduce wasteful refrigerant compression work as much as possible and save energy. Furthermore, since the desired warehouse temperature varies depending on the type of stored items, the compressor capacity control means 15 increases the capacity of the compressor 1 from the lowest stage when entering the limit temperature range according to the desired warehouse temperature. The number of stages can be changed, and the desired internal temperature is 10℃.
In the above cases, the compressor 1 is controlled in three control modes: the highest stage (100%), middle stage (67%) and lowest stage (33%), while if the desired chamber temperature is less than 10°C Since the compressor 1 is controlled in two control modes: middle stage (67%) and lowest stage (33%), when the desired warehouse temperature is low and the refrigeration load is low and no ventilation is required, The compressor 1 is not operated at high capacity (100%) with the highest stage remaining, and the compressor 1 can be operated in a mode that increases the number of stages depending on the type of stored items in the refrigerator, that is, the desired temperature inside the refrigerator. The refrigerant refrigerant can be operated at a relatively low capacity and at an optimum capacity stage, thereby further reducing wasteful refrigerant compression work and further saving energy.

In addition, in the case of pull-up in the refrigerator, step (S ₄ ) of the control flow (Fig. 4) during pull-down mentioned above.
, compressor 1 is set to the highest stage and has a high capacity (100
%) By performing heating operation, the temperature inside the refrigerator is raised to within the limit temperature range. In other respects, by performing the same control as in the above-mentioned pulldown (steps (S ₁ ) to (S ₂₃ ) in FIG. 4), the same operations and effects as in the above-mentioned pulldown can be achieved.

In addition, the compressor capacity control may use either the suction side or the blowout side temperature sensor 13b, 13a.
From the viewpoint of preventing air temperature hunting, it is preferable to use the temperature sensor 13b on the suction side.

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 point with the bypass passage 8. It is also possible to achieve the same functions and effects as those of the above embodiments.

(Effects of the Invention) As described above, the present invention provides an operation control device for a refrigeration system that performs compressor capacity control by the compressor capacity control means and hot gas refrigerant bypass control by the hot gas control means in parallel. Each time the temperature enters the limit temperature range, the capacity of the compressor is gradually increased from the lowest stage, and when the temperature enters the limit temperature range, the compressor capacity control means is controlled according to the desired temperature in the warehouse determined by the type of stored items. Since the capacity of the compressor is controlled by changing the number of stages in which the compressor capacity increases from the lowest stage, the compression The machine can be operated appropriately at the lowest possible capacity stage and at the optimum capacity stage, and wasteful refrigerant compression work can be kept to a minimum, thereby saving energy.

[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 temperature inside the refrigerator during operation of the refrigeration equipment;
FIG. 6 is a diagram showing the optimal number of capacity stages of the compressor depending on the stored items in the refrigerator. A... Refrigeration device, 1... Compressor, 2... Water-cooled condenser, 3... Air-cooled condenser, 4... Expansion valve, 5...
Evaporator, 7... Circulating refrigerant circuit, 8... Bypass passage, 9... Three-way proportional valve, 12... Internal temperature setting device, 13a, 13b... Temperature sensor, 14... Hot gas control means, 15... Compressor capacity control means, 16... changing 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 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, An internal temperature setting device 12 that sets a desired internal temperature, and a temperature sensor 13a or 13b that detects the internal temperature.
and the above-mentioned chamber temperature setting device 12 and temperature sensor 1.
3a or 13b, and a hot gas control means 14 for controlling the adjusting means 9 so that the temperature inside the refrigerator reaches the desired temperature inside the refrigerator, the refrigerator temperature setting device 12
In response to the output of the temperature sensor 13a or 13b, the capacity of the compressor 1 is set to a high capacity when the temperature inside the refrigerator is outside the limit temperature range set with a predetermined width with respect to the desired temperature inside the refrigerator; When the temperature falls within the above-mentioned limit temperature range, the capacity of the compressor 1 is initially set to the lowest stage, and then the capacity stage of the compressor 1 is gradually increased each time the temperature inside the refrigerator exceeds the above-mentioned limit temperature range and re-enters the range. a compressor capacity control means 15 for controlling the compressor capacity to
and a changing means 16 for changing the number of stages to be increased from the lowest stage of the compressor 1 capacity when entering the limit temperature range by the compressor capacity control means 15 in response to the output of the desired chamber temperature. An operation control device for a refrigeration system, characterized in that: