JPH03217744A - Operation control system for temperature control device - 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 provides an operation control method for a temperature control device incorporating a plurality of refrigeration cycles each including a refrigerant compressor, an evaporator, a condenser, a pressure reduction mechanism, and a reheater. It is related to.

[Prior Art] Air conditioners or temperature control devices that utilize a refrigeration cycle to maintain a desired temperature in a living room, an environmental test chamber, a constant temperature room, etc. are well known in the art. Various types of these air conditioners or temperature control devices have been proposed. For example, JP-A-59-1.15959, JP-A-59-16
Japanese Patent No. 4873 proposes a temperature control device incorporating a refrigeration cycle and an electric heater. According to this device, since the capacity of the electric heater can be controlled while operating the refrigeration cycle, the device has the feature that the room temperature can be controlled with high precision, but has the disadvantage that energy consumption is large. Therefore, a temperature control device using only a refrigeration cycle has been proposed, for example, in Japanese Patent Laid-Open No. 59-38568. This refrigeration cycle is equipped with a westward valve, and by switching this valve, the indoor heat exchanger can be used selectively as a cooler or a heater. This device does not have an electric heater, so it has the advantage of low power consumption, but it also uses a four-way valve to selectively use the heat exchanger for the cooler and heater. The disadvantage is that detailed control is not possible.

On the other hand, in recent years, temperature control devices that incorporate a reheater using a refrigerant in the refrigeration cycle have been proposed, and furthermore, temperature control devices that incorporate multiple refrigeration cycles each having such a reheater have also been proposed. ing. This type of temperature control device adjusts the flow rate of refrigerant using a refrigerant flow control valve installed on the reheater side in response to load fluctuations, thereby maintaining a balance between the heating capacity of the reheater and the cooling capacity of the evaporator. The room temperature is controlled to a predetermined temperature. In addition, in response to large load changes, the number of operating refrigeration cycles is controlled.

[Problem to be solved by the invention] By incorporating a reheater into a refrigeration cycle, energy-saving operation can be achieved. Conventional temperature control devices that are used in conjunction with switching the number of refrigeration cycles in operation do not take into account an appropriate cooperative relationship between adjusting the refrigerant flow rate to the reheater and switching the number of refrigeration cycles in operation. The temperature fluctuation range when switching the number of cycle operating units may be as large as, for example, 3 to 4° C., which has the disadvantage that a constant temperature state cannot be maintained satisfactorily. This is because the control of switching the number of operating refrigeration cycles and the control of adjusting the flow rate of refrigerant flowing to the reheater are performed independently of each other, so the flow rate of refrigerant to the reheater at the time of switching the number of operating refrigeration cycles is This is because the number of operating refrigeration cycles may be changed regardless of the situation, which tends to cause discontinuity in the cooling power or heating power.

Therefore, the present invention provides a temperature control device in which a plurality of refrigeration cycles each having a reheater are incorporated, and when large fluctuations occur in the load, causing discontinuity in the cooling power or heating power when switching the number of operating refrigeration cycles. First, the purpose is to maintain the room temperature with high precision, for example, within a range of ±1°C.

[Means for Solving the Problems] In order to achieve the above object, the gist of the present invention is as set forth in each claim. [Function] While a certain number of compressors are in operation, the refrigerant flow rate to the reheater is continuously controlled (for example, PID control) in response to load fluctuations to maintain the set temperature by controlling the capacity. When the load fluctuation becomes larger and reaches a predetermined limit temperature with respect to the set temperature, the refrigerant flow rate to the reheater is forcibly adjusted to the maximum or minimum to maintain the set temperature. If the heat load fluctuation becomes even larger, the number of operating compressors will be changed. At this time, when the number of units in operation is increasing, the refrigerant flow rate to the reheater is forcibly increased to the maximum value, and
When the number of operating units is decreasing, the refrigerant flow rate is forcibly reduced to the minimum value at the same time, and after switching, the same control as above is continued. This makes it possible to prevent sudden changes in cooling capacity due to changes in the number of operating compressors.

[Embodiment] Fig. 1 shows the internal structure arrangement of an air conditioner according to an embodiment of the present invention, and Fig. 2 shows its refrigeration cycle system.

Two sets of refrigeration cycles each having compressors 1 and 3 are provided within the modulator main body. In addition, a blower fan 50 is provided in the upper position of the main body, near the air intake port 5l (
or air temperature sensor 53 (near the air outlet 52)
or 54) is further provided with an auxiliary heater 55 near the center.
is provided.

Each refrigeration cycle is equipped with an evaporator 13, 33 and a reheater 14, 34, respectively, and in the air flow generated by the fan 50, these reheaters are arranged downstream of the evaporator. When the refrigeration cycle is operated and the fan 50 is rotated, indoor air to be conditioned is sucked into the main body through the suction port 51, exchanges heat with the evaporator 13, 33, and is cooled. ．． ．． 34 (this is a type of condenser), and is blown out from the blower opening 52 into the room as temperature-controlled air. The air flow at this time is indicated by arrows a, b,
Indicated by c.

The lower position of the main body receives the detected air temperature from the temperature sensor 53 (or 54), compares it with the set temperature, and uses the deviation signal to switch the number of operating compressors, as described later, or to perform reheating. A control unit 55 is disposed to perform controls necessary for operation of the temperature control device, such as transmitting an applied voltage signal for opening degree control to the refrigerant flow rate regulating valve.

FIG. 2 is a diagram showing the above two sets of refrigeration cycles in detail. One set of refrigeration cycle elements is written without parentheses,
In addition, if the elements of another set of refrigeration cycles are written in parentheses and with quotation marks, each refrigeration cycle consists of compressor 1 (3), condenser 12 (32), and evaporator 1 3 (3 3). The refrigerant flow path includes a reheater 14 (34) connected in parallel between the upstream side and the downstream side of the condenser 12 (32). And evaporator 13 (33)
An expansion valve 17 as an expansion mechanism is installed in the middle of the branch pipe leading to
(37), and a refrigerant flow rate regulating valve 18 (38) whose flow rate is controlled by an applied voltage is interposed in the middle of the branch pipe line from which the refrigerant returns from the reheater. In addition,
The condenser 12 (32) is installed outdoors.

The compressors 1 and 3 are operated on or off (that is, operated or stopped), while the refrigerant flow control valves 18 and 38 of the reheaters 14 and 34 are fully closed and closed, respectively. Continuous opening control (PI'D control) including full opening is performed.

In addition, the cooling power when both compressors 1 and 3 are operated and both reheater refrigerant flow rate adjustment valves 18 and 38 are fully open (that is, the cooling power from both evaporators 13 and 33 and the reheater refrigerant flow rate adjustment valves 18 and 38) 14 and the maximum heating power due to
8.38 are both designed to be slightly smaller than the cooling power when the system is completely idle (that is, the cooling power by only the evaporator of one refrigeration cycle).

Note that, of course, the maximum heating power by the reheater in each set of refrigeration cycle is smaller than the cooling power by the evaporator.

Next, the operation control controlled by the control section 55 in this embodiment with the above configuration will be explained.

In FIG. 3, To is the target temperature, that is, the set temperature, and above and below the target temperature are the allowable limit temperatures T and T.
2. Are the differential limit temperatures Tc, Tc, for switching the number of compressors in operation, and the limit temperatures TR■ and TR2 for adjusting the reheater refrigerant flow rate set? ing. Temperature range (T
c■-Tcz) and ('rit■-TR2) are approximately 70% and approximately 50% of the allowable temperature range (Ta'rz), respectively.
It is stipulated in

When the air temperature detected by the temperature sensor 53 (or 54) is between the temperature Tc and T02, the control unit 55 controls the refrigerant flow rate adjustment valve 18.38 without changing the number of operating compressors. The reheater refrigerant flow rate is adjusted by controlling the opening of the valve by controlling the applied voltage. That is, temperatures Tel and T. If the detected temperature is higher than temperature TR■ within the temperature range between 2 and 2, the valve is completely turned off and temperature TR
■In the following cases, the above valve is fully opened, and between TR1 and TR2, the detected temperature and set temperature T. The valve opening degree is PID controlled based on the difference from J. Such control of the reheater alone cannot keep up, and the detected air temperature falls within the temperature range Tc-T.
When exiting from 02, the number of operating compressors is switched.

This will be explained in detail below. Now, if the air temperature detected by the temperature sensor 53 (or 54) is T1 or higher, both compressors 1 and 3 are operated, and the flow rate regulating valves 18, ? 8 are both fully opened (that is, both reheaters 14 and 34 are inactive), so that the air is cooled by the two evaporators 13 and 33. The air temperature is TR, and T. When the temperature has dropped to between (2), the opening degree of the flow rate adjustment valve 18.38 is adjusted to the air detection temperature and the set temperature T while the two compressors are still operating. Both reheaters 14 are controlled by PID based on the difference between
, 34 is PID-controlled, thereby controlling the detected temperature to be maintained within the temperature range between TR2 and TR2. When the detected temperature drops to T1■, the flow rate adjustment valve 18
, 38 are fully opened to fully operate both reheaters 14, 34, and the detected temperature is set to T. Try to return the temperature to between ■ and T1■. Conversely, when the detected temperature rises to T1■, the flow rate adjustment valve 18.38 is fully closed, both reheaters 14 and 34 are rendered inactive, and the detected temperature is returned to the temperature between T1■ and TR■. 6 In this way, control is performed to maintain the detected temperature at a temperature between Tl and TR2 while the two compressors remain in operation.

If the flow rate regulating valve 1 is set as described above at the temperature T12,
8. Fully open 38 and reheater 14, 34? When the detected temperature further drops to temperature Tc2 despite the effect of the Heaters 14, 34 are rendered inactive. As a result, the detected temperature is returned to a temperature between T, and TR2, and TR
When the temperature returns to between TR1 and TR2, the opening degree of the flow rate regulating valve 18.38 is PID-controlled based on the difference between the detected temperature and the set temperature T0 while one compressor remains in operation. While performing this PID control, when the detected temperature drops to TR2, the flow rate adjustment valve 18.38 is fully opened and the detected temperature is reduced to TR2.
The temperature should be returned to between 2 and TR1.

When the detected temperature rises to temperature TR■ with one compressor in operation and PID control as described above, the flow rate regulating valves 18 and 38 are fully closed. Even so, if the detected temperature continues to rise and reaches temperature T01, the compressor 2
At the same time as switching to machine operation, the flow rate adjustment valve 18.38 is switched to full open, and if the detected temperature returns to between TR■ and T, then? While the two compressors remain in operation, PID control of the opening of the flow control valves 18 and 38 is performed as described above.

Also, if while continuing the control with one compressor operating as described above, the detected temperature further drops to temperature Tc2 even though the flow rate adjustment valves 18 and 38 are fully opened at temperature TR■. In this case, by stopping all the compressors (that is, reducing the number of operating units to zero), the operation of the refrigeration cycle is reduced to zero. As a result, the detected temperature (indoor air temperature)
(In this case, use the auxiliary heater 5 as necessary.
5).

As described above, the number of operating compressors is switched and the flow rate of refrigerant to the reheater is controlled.

FIG. 4 shows the reheater refrigerant flow rate regulating valve 18 in the above embodiment.
, 38 and the number of compressors in operation. The valve is fully opened with an applied voltage of 200V. It is fully opened at 6V, and the opening degree is continuously variable in the applied voltage range between these, and the above-mentioned PID control is performed within this range. As shown in the figure, as described above, when switching from one compressor operation to two compressor operation, the opening degree of the reheater refrigerant flow rate regulating valve 18.38 is forcibly switched to full open at the same time as the switching.

Furthermore, when switching from two-unit operation to one-unit operation, the opening degree of the valve is forcibly switched to full idle at the same time.

FIG. 5 shows a control flowchart.

[Effects of the Invention] As detailed above, according to the present invention, in a temperature control device having a plurality of refrigeration cycles incorporating a reheater, switching control of the number of operating compressors, that is, refrigeration cycles, and control of the reheater are performed. Since the control is performed in conjunction with the control of the flow rate of the refrigerant flowing, it is possible to continuously control the capacity of cooling power and reheating power, and the control temperature can be controlled with high precision, for example ±
The temperature can be maintained within the range of 1°C, and energy-saving operation is possible.

[Brief explanation of drawings]

Fig. 1 is a side view showing a schematic configuration of an air conditioner that is an embodiment of the present invention, Fig. 2 is a detailed view of a refrigeration cycle in the same embodiment, and Fig. 3 is an illustrative diagram of the progress of operating conditions during operation. , Figure 4 is an explanatory diagram of the applied voltage of the reheater refrigerant flow rate adjustment valve, Figure 5
The figure is a flow chart diagram of temperature control. 1,3...Compressor 12.32...Condenser 13
．． 33...Evaporator 14,34...Reheater 18,3
8... Reheater refrigerant flow rate adjustment valve 53.54... Air temperature sensor (1 other person) Fig. 1 Fig. 3 Fig. 4 Fig. Elapsed time

Claims (1)

[Scope of Claims] 1. A system comprising a plurality of refrigeration cycles each including a refrigerant compressor, an evaporator, a condenser, a depressurization mechanism, and a reheater, and a temperature sensor for detecting the ambient temperature in the temperature control space; The ambient temperature is maintained at the set temperature by switching the number of operating refrigerant compressors and controlling the refrigerant flow rate of the reheater according to the heat load using the cooling power of the reheater and the heating power of the reheater. In the operation control method of the temperature control device, when the number of operating refrigerant compressors is switched to increase, at the same time, the refrigerant flow rate of the reheater is forced to the maximum, and the number of operating compressors is switched to decrease. Sometimes, at the same time, the refrigerant flow rate in the reheater is forcibly controlled to be minimized, and
An operation control method for a temperature control device, characterized in that when there is no change in the number of operating compressors, the refrigerant flow rate of the reheater is continuously controlled according to the deviation between the temperature detected by the temperature sensor and the set temperature. 2. In the control of the refrigerant flow rate of the reheater when there is no change in the number of operating compressors, the temperature detected by the temperature sensor is equal to or higher than a predetermined limit temperature above the set temperature or below a predetermined limit temperature below the set temperature. 2. The operation control system for a temperature control device according to claim 1, wherein the refrigerant flow rate of the reheater is controlled to be maximum or minimum at certain times.