JP3482647B2 - Operation control device for refrigeration equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating machine operation control device which heats or cools a liquid such as water flowing through a liquid flow circuit by heat exchange with a refrigerant, and particularly, the control performance thereof is improved. Regarding measures.

[0002]

2. Description of the Related Art Conventionally, for example, JP-A-3-14855.
As disclosed in Japanese Patent No. 0, a compressor, a heat source side heat exchanger,
A refrigerant circuit in which an expansion mechanism and a use side heat exchanger are sequentially connected, and a chiller circuit in which a cooling liquid circulates are provided, and the use side heat exchanger performs heat exchange between the refrigerant in the refrigerant circuit and the cooling liquid in the chiller circuit. In the refrigerating apparatus configured to perform the operation, the water temperature at the outlet side of the heat exchanger on the use side is compared with the control target value at every predetermined sampling time to control the capacity of the compressor in a plurality of load steps, and at the side of the use side. When the water temperature at the outlet side of the heat exchanger greatly deviates from the control target value to the capacity request side or the capacity non-request side, the sampling time for performing capacity control is shortened to improve the controllability of control against a sudden load change. What is to be improved is a known technique.

[0003]

According to the above-mentioned conventional publication, when the load is abruptly fluctuated and greatly deviates from the keep area, the convergence to the keep area is delayed in the control in which the normal sampling time is constant. This is because the controllability of the water temperature may deteriorate. That is, normally
If the sampling time is too long, the control followability will deteriorate.On the other hand, if the sampling time is too short, the compressor capacity will be changed frequently and control will become unstable. It is set to a value that seems to be optimal in terms of balance with sex. However, when the load fluctuates abruptly, it is more important than the stability of control to follow the capability control that immediately responds to the fluctuating load. Therefore, by performing the sampling time change control as described above, it is possible to improve the control followability without impairing the control stability under normal conditions.

However, in the sampling time change control according to the above-mentioned conventional publication, the sampling time is changed only when the outlet water temperature largely deviates from the control target value.
Although the followability after that improved, there was a feeling that the measures would be ex post facto. That is, the fluctuation of the load is caused by the increase / decrease of the circulating amount of the cooling liquid in the chiller circuit, the change of the heat load, etc. In that case, as shown in FIG. After that, the outlet water temperature Two changes with a constant control delay. Therefore, even if the change of the outlet water temperature Two is checked and the sampling time tsamp for controlling the capacity of the compressor is changed to be shortened, the predetermined time delay cannot be eliminated. On the other hand, when the inlet water temperature Twi is always used as the control index, such a time delay is almost eliminated, but on the other hand, it becomes difficult to accurately converge the water temperature supplied to the utilization system of the chiller circuit to the original control target value. .

The present invention has been made in view of the above problems, and a first object thereof is to use the liquid temperature at the outlet side of the heat exchanger of the use side as a control index and to determine the capacity of the compressor at every predetermined sampling time. While controlling, also monitor the change in the liquid temperature on the inlet side of the heat exchanger on the use side, and if the change in the inlet liquid temperature becomes large enough to deviate from the stable state, control to shorten the sampling interval of capacity control should be performed. By doing so, it is intended to improve the followability of the capacity control with respect to changes in the load while maintaining the control stability.

A second object of the present invention is to provide a temperature difference between the capacity of the compressor under normal conditions (load step) and the inlet liquid temperature of the utilization side heat exchanger-the outlet liquid temperature (inlet / outlet liquid temperature difference). If the change in the inlet liquid temperature becomes large enough to deviate from the stable state, the capacity of the compressor is calculated as the sum of the inlet liquid temperature and the inlet / outlet temperature difference at that time. It is intended to maintain control stability and improve followability by switching to the so-called inlet liquid temperature control in which the load step is controlled so that the outlet temperature corresponding to the control target value matches as much as possible.

[0007]

Means for Solving the Problems In order to achieve the first object, the means of the invention of claim 1 is, as shown in FIG. 1, a compressor whose operating capacity is adjusted to a plurality of load steps ( 1), a heat source side heat exchanger (2), and an expansion mechanism (4)
And a refrigerant circuit (7) which sequentially connects a utilization side heat exchanger (5) for exchanging heat between the liquid flowing through the liquid flow passage (20) and the refrigerant.

As an operation control device for the refrigeration system,
An outlet liquid temperature detecting means (Th2) for detecting the liquid temperature at the outlet side of the utilization side heat exchanger (5) in the liquid flow passage (20), and the outlet liquid temperature detecting means (Th2) at predetermined time intervals. Capacity control means (51) for adjusting the operating capacity of the compressor (1) according to the temperature difference between the liquid temperature at the outlet side of the utilization side heat exchanger (5) and the control target value. And shall be provided.

Further, the inlet side liquid temperature detecting means (Th1) for detecting the inlet side liquid temperature detecting means (Th1) and the detected value of the inlet side liquid temperature detecting means (Th1) are input every moment and used. Liquid temperature change calculation means (52) for calculating the time change of the liquid temperature on the inlet side of the side heat exchanger (5), and the inlet of the use side heat exchanger (5) calculated by the liquid temperature change calculation means (52) When the time variation of the liquid temperature on the side becomes larger as it deviates from the stable state, the time interval changing means (53) for changing the time interval of the capacity control means (51) to be shorter than the reference value is provided. Is.

According to a second aspect of the present invention, in the first aspect of the present invention, the time interval changing means (53) is set so that the liquid temperature at the inlet side of the utilization side heat exchanger (5) changes with time. The capacity control means (51) is configured to increase the amount of time interval reduction.

According to a third aspect of the invention, in the second aspect of the invention, the inlet liquid temperature detecting means is provided after the time interval of the capacity control means (51) is shortened by the time interval changing means (53). When the liquid temperature at the inlet side of the utilization side heat exchanger (5) detected at (Th1) becomes stable, the time interval gradually returned to the reference value by the time interval changing means (53). A reset means is provided.

In order to achieve the second object, the invention according to claim 4
The means taken by the invention of claim 1 is based on the same refrigeration system as the invention of claim 1, and the outlet liquid temperature detection means (Th2), the capacity control means (51), and the inlet similar to those of the invention of claim 1 are provided. A liquid temperature detecting means (Th1) and a liquid temperature change calculating means (52) are provided.

Further, as shown by the broken line portion in FIG. 1, the inlet liquid temperature detecting means (Th1) and the outlet liquid temperature detecting means (T
Inlet / outlet temperature difference calculating means (54) for receiving the output of h2) and calculating the temperature difference (inlet / outlet temperature difference) between the inlet liquid temperature and the outlet liquid temperature.
And a correlation between the load step of the compressor and the inlet / outlet temperature difference calculated by the inlet / outlet temperature difference calculating means in a stable state in which the liquid temperature on the outlet side of the use side heat exchanger (5) is near the control target temperature. When the change of the liquid temperature at the inlet side of the utilization side heat exchanger (5) calculated by the storage means (31) for storing the above and the liquid temperature change calculation means (52) is large enough to deviate from the stable state, the capacity control is performed. The control of the means (51) is forcibly stopped, and the operating capacity of the compressor (1) is set to the temperature of the inlet liquid temperature detected by the inlet liquid temperature detecting means (Th1) and the control target value of the outlet liquid temperature. The control index switching means (55) for switching the control index so that the load step corresponds to the inlet / outlet temperature difference closest to the difference is provided.

[0014]

With the above structure, in the first aspect of the invention, the capacity control means (51) controls the liquid temperature at the outlet side (outlet liquid temperature) of the utilization side heat exchanger (5) at a predetermined time interval. As, the capacity of the compressor (1) is controlled at each load step.

At this time, when the change in the liquid temperature (inlet liquid temperature) on the inlet side of the utilization side heat exchanger (5) calculated by the liquid temperature change calculating means (52) becomes large enough to deviate from the stable state, the time interval is changed. The means (53) shortens the time interval of the capacity control using the outlet liquid temperature as an index. Therefore, when there is a change in the load or the like, the capacity of the compressor (1) is controlled in response to the effect of the change in the outlet liquid temperature.

That is, the stability of control in a normal stable state is not impaired, and the followability of capacity control with respect to sudden changes in load and the like is improved.

In the invention of claim 2, in the operation of the invention of claim 1, the greater the time change of the liquid temperature at the inlet side of the utilization side heat exchanger (5), the more the time interval is shortened. It is possible to adjust the balance between stable control stability and followability.

According to the third aspect of the present invention, when there is a change in the load or the like, a sudden change appears after that even if the liquid temperature at the inlet side of the utilization side heat exchanger (5) is stable. However, since the shortened time interval is gradually restored to the reference value by the time interval restoring means, the control stability is ensured.

According to the fourth aspect of the present invention, in the stable control state, the capacity control means (51) uses the liquid temperature (outlet liquid temperature) on the outlet side of the utilization side heat exchanger (5) as a control index for the compressor ( Although the capacity control of 1) is performed, when the load fluctuation or the like is large, there is a possibility that the control followability deteriorates.

Here, when the time change of the liquid temperature (inlet liquid temperature) on the inlet side of the utilization side heat exchanger (5) becomes so large that it deviates from the stable state, the control index switching means (55) causes the compressor (1) to change. Based on the correlation between the load step of the compressor (1) and the inlet / outlet temperature difference stored in the storage means (31), it is closest to the temperature difference between the inlet liquid temperature and the control target value at that time. The load step is controlled to correspond to the inlet / outlet temperature difference. In that case, from the correlation between the load step of the compressor (1) and the inlet / outlet temperature difference calculated by the inlet / outlet temperature difference calculating means (54), the outlet liquid temperature corresponding to the inlet liquid temperature is determined by the compressor (1). Once the load step is determined, it is uniquely expected for it.

Therefore, by switching the control index in this way, the outlet liquid temperature is eventually controlled so as to match the control target value, and the inlet liquid temperature that has changed more rapidly is used as the control index. Thus, the control followability is improved.

[0022]

Embodiments of the present invention will be described below with reference to the drawings starting from FIG.

FIG. 2 shows a refrigerant piping system of an air conditioner according to an embodiment of the present invention. The air conditioner has a refrigerator (A) having a closed refrigerant circuit (7) in which a refrigerant circulates.
And a utilization system (B) having a circulation path (20) in which chilled water for cooling is circulated in the summer and hot water for heating is circulated in the winter, and the refrigerator (A) and the utilization system (B). ) And a controller (C) for controlling the operation.

The refrigerant circuit (7) of the refrigerator (A) includes a compressor (1) provided with an unloader (9) described later, and a solid line in the figure during a cooling operation, and a broken line in the figure during a heating operation. An air-side heat, which is a heat-source-side heat exchanger that includes a four-way switching valve (20RS) that is switched and a pair of fin units (2a) and (2b) and functions as a condenser during cooling operation and as an evaporator during heating operation. An exchanger (2), a receiver (3) for storing liquid refrigerant, an expansion mechanism (4) for expanding the refrigerant, and a user side that functions as an evaporator during cooling operation and as a condenser during heating operation. It is configured as a closed circuit in which a water side heat exchanger (5) which is a heat exchanger is connected by a refrigerant pipe (6).

Here, the unloader (9) has three first to third on-off valves (20R1) to (20R3) between the three intermediate pressure portions of the compressor (1) and the suction side. It is installed in parallel, and the operating capacity of the compressor (1) (load step)
To full load (100%) when all the on-off valves (20R1) to (20R3) are closed, and the third on-off valve (2
0R3) only opens to 75% load, and 3rd and 2nd on-off valves (20R3), (20R2) open to 5%
All open / close valves (20R1) to (20R3) at 0% load
When the valve is opened, the load is set to 25%, that is, when 0% in the stopped state is included, the operating capacity of the compressor (1) is adjusted to four load steps.

Further, the expansion mechanism (4) is formed by connecting an expansion valve for cooling operation (20E1) which is an external pressure equalizing type temperature type automatic expansion valve and a first capillary tube (CP1) in parallel. A second expansion path formed by connecting the first expansion path (4a), the heating operation expansion valve (20E2), which is an external pressure-equalizing temperature automatic expansion valve, and the second capillary tube (CP2) in parallel. (4b) and a third expansion path (4c) formed by interposing a third capillary tube (CP3).

That is, during the cooling operation, the four-way switching valve (20RS) is switched as shown by the solid line in the figure, so that the refrigerant discharged from the compressor (1) is condensed and liquefied in the air side heat exchanger (2). After being stored in the receiver (3), the first
It is expanded in the expansion path (4a), evaporated in the water side heat exchanger (5), and circulated so as to return to the compressor (1) (see a solid arrow in the figure). At this time, the water side heat exchanger (5)
Then, the circulating water is cooled by heat exchange with the circulating water of the utilization system (B) to be chilled water, and the cold heat is used for cooling the utilization system (B). On the other hand, during the heating operation, the four-way switching valve (20RS) is switched as shown by the broken line in the figure, so that the refrigerant discharged from the compressor (1) is the water side heat exchanger (5).
After being condensed and liquefied in the receiver (3) and stored in the receiver (3), they are expanded in the second expansion path (4b) and the third expansion path (4c), and each fin unit of the air side heat exchanger (2) ( 2a) and (2b) evaporate respectively, and the compressor (1)
(See the dashed arrow in the figure). At this time, in the water side heat exchanger (5), the circulating water is heated by the heat exchange with the circulating water of the utilization system (B) to be hot water, and the warm heat is used for heating the utilization system (B). Has been done.

Incidentally, (20R5) is a fifth opening / closing valve provided in the liquid line of the refrigerant circuit (7), and (20R6) is a degassing passage (connecting between the upper portion of the receiver (3) and the suction line ( A sixth opening / closing valve for opening / closing 11) and a seventh opening / closing valve (20R7) for opening / closing the liquid-sealing prevention passage (12).

Further, the expansion mechanism (4) and the water side heat exchanger (5) are bypassed between the liquid line on the downstream side of the receiver (3) of the refrigerant circuit (7) and the suction pipe. Liquid injection circuit (1
0) is provided, and the liquid injection circuit (10) is provided with a third expansion valve (20) which is an external pressure equalizing type temperature type automatic expansion valve for adjusting the injection amount.
E3) and the eighth opening / closing valve (20R8) are interposed.

Next, the refrigerator (A) is provided with sensors, (63D) is a high pressure switch for defrosting, and (6)
3H) is a pressure sensor for pressure control, (HLPS) is a pressure switch for high / low pressure protection, and (LPS) is a low pressure switch for pump down operation.

In the utilization system (B), an inlet water temperature sensor (Th1) as an inlet side liquid temperature detecting means for detecting the inlet side water temperature Twi of the water side heat exchanger (5), and a water side heat exchanger. (5) An outlet water temperature sensor (Th2) as an outlet side liquid temperature detecting means for detecting the outlet side water temperature Two, and an antifreezing thermostat (26) which operates at 3 ± 1 ° C. and outputs a command signal for antifreezing operation
WL) and are arranged.

On the other hand, the controller (C) has a storage circuit (3 as storage means for storing control data and the like.
1), a setting circuit (32) for setting the control target value Tws of the outlet water temperature Two, and an arithmetic circuit (33) for performing various calculations
Etc. are built in. Each of the sensors is connected to the controller (C) via a signal line, and the controller (C) detects the detection value of each of the sensors and the storage circuit (3).
The operation of the air conditioner is controlled according to the stored contents of 1), the set contents of the setting circuit (32), and the like.

Next, regarding the control content of the controller (C), a first embodiment corresponding to the control content of the invention of claim 1 will be described.

FIG. 3 shows the contents of the capacity control of the compressor (1) using the outlet water temperature Two detected by the outlet water temperature sensor (Th2) as a control index, and shows the contents above and below the control target value (set value) Tws. Is provided with upper and lower switching points (end values) Ts1 and Ts2 separated by a predetermined thermo-differential D. When the outlet water temperature Two drops, three minutes elapse after the outlet water temperature Two reaches the lower switching point Ts1. When the water temperature is lower than the lower switching point Ts1, the step value of the capacity is reduced, and when the outlet water temperature Two rises, after reaching the upper switching point Ts2, 3
If the upper switching point Ts2 is exceeded when the time elapses, the step value of the capacity is increased, while if the outlet water temperature returns to the original value after the elapse of 3 minutes even when the upper and lower switching points Ts1 and Ts2 are reached, the capacity remains unchanged. Is designed to maintain. The set value Tws is the median of the switching points Ts1 and Ts2. Further, this control is performed every predetermined sampling time tsamp, and this sampling time tsamm
p is designed to be switched among three values t1, t2, t3 by the control described later.

By the above control, the capacity control means (51) according to the invention of claim 1 is constituted.

Next, the flow chart of FIG. 4 shows the contents of the switching control of the sampling time tsamp, and step ST
In step 1, the inlet water temperature Twi detected by the inlet water temperature sensor (Th1) is stored in the storage circuit (31), and step ST
In step 2, wait for 10 seconds and then step S
Proceeding to T3, the detected value Twi ′ of the inlet water temperature sensor (Th1) at that time is input, and in step ST4, the temperature difference between the inlet water temperatures Twi and Twi ′ before and after 10 seconds, that is, the inlet water temperature change amount ΔTwi ( = Twi'-Twi) is calculated. Then, in step ST5, this time change amount Δ of the inlet water temperature
Twi is a predetermined first and second reference change value ΔT1, ΔT2 (Δ
T1 <ΔT2), and if ΔTwi <ΔT1 is in a stable state, it is determined that the sampling time tsamp does not need to be shortened, and the sampling time tsamp is set to the reference value t.
It is set to s (for example, about 30 seconds). On the other hand, ΔT
If 1 ≦ ΔTwi <ΔT2, it is determined that the sampling time tsamp needs to be shortened because the load or the like changes considerably rapidly, and the sampling time tsamp is set to the reference value t.
Switch to 2/3 of s (ie 20 seconds). Also, ΔT
If wi ≧ ΔT2, it is determined that there is a very sudden change in load, and the sampling time tsamp is set to 3 of the reference value ts.
Switch to one-half (that is, 10 seconds).

That is, the inlet water temperature Twi as shown in FIG.
In a stable state in which the change of the inlet water temperature Twi is gradual with respect to the change of time, the sampling time tsamp is set to the reference value ts (area in the figure), and the sampling time tsamp is set to (2 / 3) · ts (region in the figure), and in the region where the inlet water temperature Twi changes extremely rapidly, the sampling time tsamp can be switched to (1/3) · ts (region in the figure) to change the outlet water temperature. T
The capacity control of the compressor (1) using wo as an index is made to follow abrupt changes in load and the like.

In the above flow, the liquid temperature change calculating means (5) according to the invention of claim 1 is controlled by the control of step ST4.
2) is configured, and the time interval changing means (53) according to the invention of claim 1 is controlled by step ST7 or ST8.
Is configured.

Therefore, in the first embodiment, the capacity control means (51) causes the predetermined sampling time tsamp.
Each time, the capacity of the compressor (1) is controlled at each load step using the water temperature Two at the outlet side of the water side heat exchanger (5) as a control index.

At this time, this sampling time tsamp
Is set to a reference value ts (ts = 30 seconds in the first embodiment) which is considered to be most appropriate for the air conditioner in consideration of stability and followability of normal control. When there is a sudden change such as an increase or decrease in the heat load of the air-conditioning target or an increase or decrease in the circulating cold water amount, the inlet water temperature Twi changes abruptly accordingly, but if the capacity control is performed for each reference value ts of the sampling time tsammp. During that time, the outlet water temperature Two largely changes, so that the followability of the capacity control deteriorates.

On the other hand, in the first embodiment, when the change in the inlet water temperature Twi calculated by the liquid temperature change calculating means (52) becomes large enough to deviate from the stable state, the outlet water temperature is changed by the time interval changing means (53). Since the sampling time tsamp for capacity control with Two as an index is shortened (two-thirds or one-third in the first embodiment), the compressor (1) can be immediately adjusted in response to a change in load or the like. Ability can be controlled.

That is, as shown in FIG. 6, even if the inlet water temperature rises, it immediately converges near the target value. Therefore, the stability of the control in the normal stable state is not impaired, and the followability to a sudden change in the load can be improved.

Further, in that case, as in the first embodiment, the greater the temporal change of the inlet water temperature Twi, the larger the shortening amount of the sampling time tsamp is. The balance can be adjusted.

Although the embodiment is omitted, the sampling time tsamp shortened by the above flow is restored to the original reference value ts when the inlet water temperature Twi becomes stable thereafter, but at that time, for example, ts It is designed to gradually return rather than immediately returning from / 3 to ts. That is, as shown in FIG. 6, ts (1/3) to ts (2
/ 3), ts and gradually returns to the reference value ts. By this control, the time interval returning means according to the invention of claim 3 is constituted.

That is, once there is a change in the load or the like, the control state may not stabilize immediately thereafter and it may take some time, and in the case of a large load change, it may be the inlet water temperature Twi. Since there is a certain time lag until the influence on the temperature of the inlet water temperature Twi is stabilized, there is a possibility that a sudden change may appear thereafter. Therefore, the stability of control can be ensured by gradually returning the sampling time tsamp thus shortened to the reference value ts by the time interval returning means.

Next, a second embodiment according to the invention of claim 4 will be described.

Also in the second embodiment, the capacity control of the compressor (1) using the outlet water temperature Two as an index is the same as that shown in FIG. 3 in the first embodiment, and the capacity control means (5
The function of 1) is common.

The contents of the calculation control of the inlet / outlet temperature difference ΔTio will be described. As shown in the flow chart of FIG. 7, in step SQ1, it is determined whether or not the outlet water temperature Two is between the lower switching point Ts1 and the upper switching point Ts2, that is, in the stable state near the set temperature Tws. It is determined whether or not, and in step SQ2, ΔTb = ΔTa and ΔTc = ΔTb,
After updating the memory of the data ΔTa, ΔTb, ΔTc for obtaining the inlet / outlet temperature difference ΔTio as an average value, the data ΔT1 of the inlet / outlet temperature difference ΔTio is calculated in step SQ3 with ΔTa = Twi−Two. Then, in step SQ4, the expression ΔTio = (ΔTa + ΔTb + ΔTc) /
3, the inlet / outlet temperature difference ΔTio is calculated as the average value of the respective data ΔTa, ΔTb, ΔTc obtained from the three measurements, and when the predetermined time X seconds has elapsed in step SQ5, the control of step SQ1 and thereafter is repeated.

In the above flow, steps SQ2-S
The inlet / outlet temperature difference calculating means (54) according to the invention of claim 4 is constituted by the control of Q4.

The memory circuit (31) built in the controller (C) stores the relationship between the load step of the compressor (1) in the stable state and the inlet / outlet temperature difference ΔTio obtained by the above control. Has been done. An example thereof is shown in Table 1 below.

[0051]

[Table 1] That is, as the capacity of the compressor (1) increases, the refrigerant circulation amount of the refrigerant circuit (7) increases, so that the heating or cooling capacity of the water side heat exchanger (5) increases.
The inlet / outlet temperature difference ΔTio also increases. However, usage system (B)
When the water circulation amount of the circulation path (20) of No. 1 changes, the inlet / outlet temperature difference ΔTio for the same load step changes,
Correlation as shown in Table 1 above is stored as a map with respect to changes in the water circulation amount.

Next, FIG. 8 shows a flow of control. After performing the same control as steps ST1 to ST4 (see FIG. 4) in the first embodiment in steps SR1 to SR4,
In step SR5, the change amount ΔTwi of the inlet water temperature is the first
It is determined whether or not it is the reference change value ΔT1 or more. And ΔT
If wi ≧ ΔT1 is not satisfied, it is determined that the stable state is reached, the process proceeds to step SR6, the detected value Two of the outlet water temperature sensor (Th2) is input, and the differential temperature ΔT (= T
After calculating wo-Ts), the operating capacity of the compressor (1) is controlled as described above (see FIG. 3) according to the temperature difference Δ.

On the other hand, if the determination in step SR5 is made, ΔT
When wi ≧ ΔT1, the process proceeds to step SR9, the temperature difference ΔT ′ between the inlet water temperature Twi ′ and the control target temperature Ts is calculated, and this temperature difference ΔT ′ is calculated in step SR10 as the load step and the inlet / outlet temperature difference. Compare with the map of the correlation with ΔTio. Then, in step SR11, the load step corresponding to the inlet / outlet temperature difference ΔTio closest to the temperature difference ΔT ′ is selected. For example, in Table 1 above, the capacity of the compressor (1) is currently operating at a load of 50%, the inlet water temperature Twi is 13 ° C., and the outlet water temperature is the set temperature (control target value).
If Tws is 7 ° C., ΔT ′ = 6 (° C.), and the closest inlet / outlet temperature difference ΔTio is 6 ° C., so the load step of the compressor (1) is eventually selected as 75% load. Become.

In the above flow, steps SR9-S
The control of R11 constitutes the control index switching means (55) according to the invention of claim 4.

Therefore, in the second embodiment, in the stable control state, the capacity control means (51) uses the outlet water temperature Two of the water side heat exchanger (5) as a control index to control the capacity of the compressor (1). The control is performed, but as described above, when the load variation or the like is large, the control followability may be deteriorated.

Here, in the second embodiment, when the change ΔTwi in the inlet water temperature exceeds the predetermined reference change value ΔT1, the control index switching means (55) causes the operating capacity of the compressor (1) to change to the storage circuit. Based on the correlation between the load step of the compressor (1) and the inlet / outlet temperature difference ΔTio stored in (31), it corresponds to the inlet / outlet temperature difference ΔTio closest to the temperature difference between the inlet water temperature Twi and the set temperature Tws at that time. It is controlled to change to the load step. In other words, the control index has been switched from the outlet water temperature Two to the inlet water temperature Twi.

The relationship between the inlet water temperature Twi and the outlet water temperature Two at this time will be described. As shown in FIG. 9, in the stable state during cooling operation (area in the figure), the inlet water temperature Twi shown by the solid line in the figure. The outlet water temperature Two shown by a broken line and the outlet water temperature Two show the same time change with a constant temperature difference ΔTio (for example, 5 ° C. in the same figure), but when the inlet water temperature Twi suddenly changes due to a change in load (region in the figure) When the capacity control of the compressor (1) is performed using the outlet water temperature Two as a control index as it is, the outlet water temperature T
wo does not immediately follow the change in the inlet water temperature Twi, but
The change of the outlet water temperature Two occurs after a while.

On the other hand, the inlet / outlet temperature difference Δ calculated by the load step of the compressor (1) and the inlet / outlet temperature calculating means (54).
From the correlation with Tio, the outlet water temperature Two corresponding to the inlet water temperature Twi is uniquely predicted when the load step of the compressor (1) is determined. Therefore, by switching the control index in this way, the outlet water temperature Two is eventually controlled so as to match the set temperature Tws (see the broken line portion in the figure), and the inlet water temperature Twi that changes faster appears. By using the index as the control index, the followability of the control is improved.

In the above embodiment, the liquid flow passage is the circulation path (20) of the utilization system (B), that is, the closed system, but the present invention is not limited to this embodiment, and the liquid flow passage is It may be an open system. The liquid flowing through the liquid flow passage is not limited to water, but may be a liquid such as brine or an aqueous solution.

[0060]

As described above, according to the first aspect of the present invention, the compressor having the operating capacity adjusted to a plurality of load steps is provided, and the refrigerant flowing through the refrigerant and the liquid flow passage in the utilization side heat exchanger. As an operation control device for a refrigeration system configured to perform heat exchange with a compressor, the compressor is operated at predetermined time intervals in accordance with the temperature difference between the outlet liquid temperature of the heat exchanger in the liquid flow passage and the control target value. While controlling the operating capacity, if the time change of the inlet liquid temperature of the heat exchanger on the use side becomes large enough to deviate from the stable state, the time interval for capacity control is changed to be shorter than the reference value. It is possible to control the capacity of the compressor in response to the fluctuation of the above condition. Therefore, it is possible to improve the followability of the control in the changed state without impairing the stability of the control in the normal stable state.

According to the second aspect of the present invention, in the first aspect of the invention, the smaller the time interval of the inlet liquid temperature is, the larger the time interval is shortened. The balance with the followability can be adjusted.

According to the invention of claim 3, in the invention of claim 1 or 2, the shortened time interval is set when the inlet liquid temperature becomes stable after the time interval for volume control is shortened. Since the value is gradually returned to the reference value, it is possible to effectively prevent the control from becoming unstable due to the delay of the influence of the fluctuation of the load on the liquid temperature.

According to the fourth aspect of the present invention, a compressor whose operating capacity is adjusted to a plurality of load steps is provided, and heat is exchanged between the refrigerant and the liquid flowing through the liquid flow passage in the utilization side heat exchanger. As an operation control device for the refrigeration system, it controls the operating capacity of the compressor at a predetermined time interval according to the temperature difference between the outlet liquid temperature of the utilization side heat exchanger in the liquid flow passage and the control target value, while stabilizing the operation capacity. The correlation between the load step of the compressor in the state and the inlet / outlet temperature difference is stored in advance, and when the time change of the inlet liquid temperature of the utilization side heat exchanger becomes large enough to deviate from the stable state, the operating capacity of the compressor Based on the correlation
Since the control index is switched so that the load step corresponds to the inlet / outlet temperature difference that is closest to the temperature difference between the inlet liquid temperature and the control target value at that time, the inlet that has an immediate effect in response to changes in load etc. The volume control can be performed so that the outlet liquid temperature matches the control target value while using the liquid temperature as a control index. Therefore, while ensuring the stability of the control in the stable state, the followability of the control in the changed state can be improved. Can be planned.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of the invention.

FIG. 2 is a piping system diagram of the air conditioning apparatus according to the embodiment.

FIG. 3 is a switching characteristic diagram showing a method for controlling the outlet water temperature.

FIG. 4 is a flowchart showing the contents of sampling time switching control for capacity control.

FIG. 5 is an explanatory diagram showing a relationship between a change in inlet water temperature and a control sampling time.

FIG. 6 is an explanatory diagram showing a state in which control followability is improved by changing a sampling time.

FIG. 7 is a flowchart showing the control contents for obtaining the correlation between the load step of the compressor and the inlet / outlet temperature difference.

FIG. 8 is a flowchart showing the contents of control index switching control.
FIG.

FIG. 9 is a diagram showing an example of a temporal change in water temperature due to the capacity control of the second embodiment.

FIG. 10 is a diagram showing a change in water temperature due to conventional outlet water temperature control.

[Explanation of symbols]

1 compressor 2 Air side heat exchanger (heat source side heat exchanger) 4 Expansion mechanism 5 Water side heat exchanger (use side heat exchanger) 7 Refrigerant circuit 20 Circulation path (liquid flow path) 31 memory circuit (memory means) 51 capacity control means 52 Liquid temperature change calculation means 53 time interval change means 54 Inlet / Outlet temperature difference calculation means 55 Control index switching means Th1 inlet water temperature sensor (inlet liquid temperature detection means) Th2 outlet water temperature sensor (outlet liquid temperature detection means)

─────────────────────────────────────────────────── --Continued from the front page (56) Reference JP-A-3-148550 (JP, A) JP-A-56-157745 (JP, A) JP-A-53-117241 (JP, A) JP-A-57- 43150 (JP, A) JP-A-6-185796 (JP, A) JP-A-2-208455 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) F25B 1/00 371

Claims (4)

(57) [Claims] 1. A compressor (1) whose operating capacity is adjusted to a plurality of load steps, a heat source side heat exchanger (2), an expansion mechanism (4), and a liquid flowing through a liquid flow passage (20). A refrigeration apparatus provided with a refrigerant circuit (7) in which a user side heat exchanger (5) for exchanging heat with a refrigerant is sequentially connected, wherein the user side heat exchanger (5) in the liquid flow passage (20) is provided. An outlet liquid temperature detecting means (Th2) for detecting the liquid temperature on the outlet side, and a detection value of the outlet liquid temperature detecting means (Th2) are input at predetermined time intervals, and the outlet on the use side heat exchanger (5) And a capacity control means (51) for adjusting the operating capacity of the compressor (1) according to the temperature difference between the liquid temperature on the side and the control target value, and the inlet side of the utilization side heat exchanger (5). The inlet liquid temperature detecting means (Th1) for detecting the liquid temperature of and the detection value of the inlet liquid temperature detecting means (Th1) are input every moment and used. Liquid temperature change calculation means (52) for calculating the time change of the liquid temperature on the inlet side of the side heat exchanger (5), and the inlet of the use side heat exchanger (5) calculated by the liquid temperature change calculation means (52) And a time interval changing means (53) for changing the time interval of the capacity control means (51) so as to be shorter than a reference value when the time change of the liquid temperature on the side becomes larger as it deviates from the stable state. The operation control device for the refrigeration system. 2. The operation control device for a refrigerating apparatus according to claim 1, wherein the time interval changing means (53) has a larger capacity control means as the time change of the liquid temperature at the inlet side of the utilization side heat exchanger (5) increases. 5
An operation control device for a refrigeration system, characterized in that the reduction amount of the time interval of 1) is increased. 3. The operation control device for a refrigerating apparatus according to claim 1, wherein the capacity control means (51) comprises a time interval changing means (53).
After the time interval of is shortened, the inlet liquid temperature detection means (Th1)
When the liquid temperature at the inlet side of the utilization side heat exchanger (5) detected in step S3 becomes stable, a time interval restoring means for gradually returning the time interval changed by the time interval changing means (53) to the reference value is provided. An operation control device for a refrigeration system, which is provided. 4. A compressor (1) whose operating capacity is adjusted to a plurality of load steps, a heat source side heat exchanger (2), an expansion mechanism (4), and a liquid flowing through a liquid flow passage (20). A refrigeration apparatus provided with a refrigerant circuit (7) in which a user side heat exchanger (5) for exchanging heat with a refrigerant is sequentially connected, wherein the user side heat exchanger (5) in the liquid flow passage (20) is provided. An outlet liquid temperature detecting means (Th2) for detecting the liquid temperature on the outlet side, and a detection value of the outlet liquid temperature detecting means (Th2) are input at predetermined time intervals, and the outlet on the use side heat exchanger (5) And a capacity control means (51) for adjusting the operating capacity of the compressor (1) according to the temperature difference between the liquid temperature on the side and the control target value, and the inlet side of the utilization side heat exchanger (5). The inlet liquid temperature detecting means (Th1) for detecting the liquid temperature of and the detection value of the inlet liquid temperature detecting means (Th1) are input every moment and used. A liquid temperature change calculating means (52) for calculating a time change of the liquid temperature at the inlet side of the side heat exchanger (5) and the outputs of the inlet liquid temperature detecting means (Th1) and the outlet liquid temperature detecting means (Th2) are received. , An inlet / outlet temperature difference calculating means (5) for calculating a temperature difference between the inlet liquid temperature and the outlet liquid temperature (inlet / outlet temperature difference).
4), and the load step of the compressor and the inlet / outlet temperature difference calculated by the inlet / outlet temperature difference calculating means in a stable state in which the liquid temperature on the outlet side of the use side heat exchanger (5) is close to the control target temperature. When the storage means (31) for storing the correlation and the change in the liquid temperature at the inlet side of the utilization side heat exchanger (5) calculated by the liquid temperature change calculating means (52) are large enough to deviate from the stable state, The control of the capacity control means (51) is forcibly stopped, and the operating capacity of the compressor (1) is set to the control target values of the inlet liquid temperature and the outlet liquid temperature detected by the inlet liquid temperature detecting means (Th1). And a control index switching means (55) for switching the control index so that the load step corresponds to the inlet / outlet temperature difference closest to the temperature difference.