JPH05280809A - Refrigeration system operation controller - Google Patents

Abstract

(57) [Abstract] [Purpose] To prevent the instability of control due to frequent start / stop of the compressor in the one in which the outlet temperature of the heat exchanger on the use side of the heat exchange medium is controlled to be constant. When the compressor 1 is stopped by the stop control means 51, the outlet temperature at that time is stored as a stop temperature in the stop temperature storage means 52, and the outlet temperature when a certain time has elapsed after the stop is the temperature of the stop temperature. The difference is stored in the reference temperature difference storage means 53 as a reference temperature difference. The return control means 53 restarts the compressor 1 when the change in the outlet temperature from the stop temperature becomes larger than the reference temperature difference by a predetermined value or more. Also, when the reference temperature difference at the time of the stop is larger than the average temperature difference of the reference temperature difference during each stop until a predetermined time or more, when the change in the outlet temperature from the stop temperature becomes larger than the average temperature difference. Return. As a result, the outlet temperature at the time of restoration is maintained at an appropriate value, the control is stabilized, and the heat exchange medium temperature is properly maintained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation control device for a refrigerating apparatus which controls the refrigerating capacity according to the outlet temperature of the heat exchange medium on the side of the use side.

[0002]

2. Description of the Related Art Conventionally, as an operation control device for a refrigeration system, a compressor, a heat source side heat exchanger, a pressure reducing mechanism and a use side heat exchanger are sequentially connected as disclosed in, for example, Japanese Patent Application Laid-Open No. 3-144256. Then, in the chiller that cools the cold water of the utilization system by heat exchange with the refrigerant in the utilization side heat exchanger, the outlet temperature of the utilization side heat exchanger of the cold water that is the heat exchange medium is detected and the outlet temperature is set. When the value is reached, the compressor is stopped for a certain period of time, for example, about 3 minutes, and when the chilled water temperature becomes higher than the temperature obtained by adding the specified differential to the set temperature after a certain period of time, the compressor is restarted. This is a known technique.

[0003]

However, the above-mentioned conventional devices have the following problems.

That is, since the heat exchange in the utilization side heat exchanger is stopped while the compressor to be compressed is stopped, the outlet temperature of the utilization side heat exchanger of the cold water becomes considerably high, and the capacity of the compressor is accordingly increased. It is controlled to increase rapidly. However, this outlet temperature decreases immediately after the heat exchange in the utilization side heat exchanger resumes, so that the outlet temperature falls below the set value immediately after the restart of the compressor. As a result, the start and stop of the compressor are frequently repeated, which causes a problem of destabilizing the control.

On the other hand, it is conceivable that the inlet temperature of the utilization side heat exchanger is detected and the start / stop timing of the compressor is controlled according to the change of the inlet temperature. Attaching the temperature sensors to both the outlet and the outlet causes an increase in cost.

The present invention has been made in view of the above point, and an object thereof is to set the outlet temperature of the heat exchange medium for the heat exchange medium to the inlet temperature after a certain time has elapsed after the compressor is stopped. Paying attention to the points that are almost equal, remember the outlet temperature at that time, and determine the restart timing of the compressor based on the relationship between this temperature and the outlet temperature to stabilize control and control performance. It is aimed at improvement.

[0007]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the means taken by the invention of claim 1 is, as shown in FIG. 1, a compressor (1), a heat source side heat exchanger (2), and a decompressor. It is assumed that the refrigerating apparatus has a refrigerant circuit (6) in which the mechanism (3) and the usage-side heat exchanger (4) are sequentially connected.

As an operation control device for the refrigeration system,
Outlet temperature detecting means (Thw) for detecting the outlet temperature of the medium to be exchanged for heat exchange with the refrigerant in the use side heat exchanger (4).
2) and the output of the outlet temperature detecting means (Thw2),
A stop control means (51) for controlling the compressor (1) to stop according to the reduction in the required capacity, and an outlet temperature when the compressor (1) is stopped by the stop control means (51). Temperature storage means (52) for storing as
And the temperature difference between the detected value of the outlet temperature detection means (Thw2) and a stop temperature stored in the stop temperature storage means (52) when a certain time has elapsed after the compressor (1) was stopped. Reference temperature difference storage means (53) for storing as a temperature difference
And the output of the outlet temperature detection means (Thw2), the contents stored in the stop temperature storage means (52) and the reference temperature difference storage means (53) indicate that the compressor (1) is stopped and the temperature is stopped. When the change in the outlet temperature exceeds the reference temperature difference by a predetermined value or more, a return control means (54) for restarting the compressor (1) is provided.

The means taken by the invention of claim 2 is, as shown by the broken line portion in FIG. 1, in the operation control device of the refrigerating apparatus according to claim 1, when the compressor (1) is stopped until then. An average temperature difference storage means (55) for storing the average value of the reference temperature differences stored in the reference temperature difference storage means (52) as an average temperature difference is provided. Then, the return control means (54) compares the reference temperature difference and the average temperature difference at the time of the stop based on the stored contents of the reference temperature difference storage means (53) and the average temperature storage means (55) to obtain a reference value. When the temperature difference is larger than the average temperature difference by a predetermined value or more, when the change in the outlet temperature from the stop temperature becomes larger than the average temperature difference by a predetermined value or more, the compressor (1) is controlled to restart. is there.

According to a third aspect of the invention, in the invention of the first or second aspect, after the compressor (1) is stopped, the compressor (1) is operated for a predetermined time longer than the predetermined time. A return limiting means (56) for prohibiting restart is provided.

[0011]

According to the invention of claim 1, when the compressor (1) is stopped by the stop control means (51), the stop temperature storage means (52).
Thus, the detected value of the outlet temperature detecting means (Thw2) is stored as the stop temperature, and after a certain time has elapsed, the outlet temperature becomes substantially equal to the inlet temperature. Then, the reference temperature difference storage means (53) stores the temperature difference between the outlet temperature and the stop temperature at this time as the reference temperature difference, and thereafter, the change in the outlet temperature from the stop temperature is a predetermined value than the reference temperature difference. When it becomes larger than the above, the return control means (54) controls to restart the compressor (1).

At that time, the outlet temperature after the elapse of a certain time after the compressor (1) is stopped becomes substantially equal to the inlet temperature, so that the reference temperature difference becomes substantially constant depending on the model. Therefore, the change value of the outlet temperature immediately before the return of the compressor (1) becomes substantially constant, and the compressor (1) is restarted in a state where the outlet temperature does not greatly deviate from the control range. Stabilize.

According to the invention of claim 2, in addition to the invention of claim 1, the reference temperature difference at this stop is the average value of the reference temperature differences stored so far in the average temperature difference storage means (55). If the change in the outlet temperature from the stop temperature becomes greater than the average temperature difference by a predetermined value or more when the predetermined temperature is exceeded,
Since it is determined that the compressor (1) should be restarted, even if a rapid change in the inlet temperature occurs due to fluctuations in the heat load of the utilization system, the heat due to the delay in restarting the compressor (1) Deterioration of controllability of the exchange medium temperature is prevented.

According to a third aspect of the invention, the first or second aspect of the invention is provided.
In the invention of claim 1, the return limiting means (56) allows the compressor (1) to continue until a predetermined time elapses after the compressor (1) is stopped.
Since the restart of the compressor (1) is prohibited, the compressor (1) immediately recovers due to a sudden decrease in the inlet temperature after the compressor (1) has stopped, etc. Stabilization is prevented.

[0015]

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 a liquid cooling device according to an embodiment of the present invention. The liquid cooling device is a utilization system for cooling a machine tool and the like, and a chilling unit (B).
The chilling unit (B) comprises a refrigerating device (A) for cooling the circulating liquid. The refrigeration system (A) includes a compressor (1) including an unloader mechanism (9) described below, and a condenser as a heat source side heat exchanger that condenses and liquefies the refrigerant discharged from the compressor (1). (2), a decompression mechanism (3) for decompressing the refrigerant liquefied in the condenser (2), and an evaporator (a utilization side heat exchanger for evaporating the refrigerant decompressed in the decompression mechanism (3) ( 4) is provided with a refrigerating circuit (6) sequentially connected with a refrigerant pipe (5).

Here, the pressure reducing mechanism (3) includes an opening / closing valve (20Rn) (n = 1 to 4) and a capillary tube (C).
n) (n = 1 to 4). And
The tube diameters of the respective capillary tubes (C1) to (C4) become smaller in order, that is, the first capillary tube (C4).
1) is large, the second capillary tube (C2) is inside,
The third capillary tube (C3) is provided in a small size and the fourth capillary tube (C4) is provided in a minimum size. Therefore, the degree of pressure reduction is gradually increased. That is, by individually opening each of the on-off valves (R1) to (R4), the decompression degree of the decompression mechanism (3) by the first to fourth capillary tubes (C1) to (C4) having different decompression degrees can be adjusted. It is designed to be adjustable.

Then, the first step (100% capacity) of the maximum capacity for opening the first opening / closing valve (20R1) by fully loading the compressor (1) and the second step by unloading the compressor (1). The second step (75% capacity) to open only the on-off valve (20R2) and the third step (50% to open only the third on-off valve (20R3) by unloading the compressor (1).
Capacity) and the minimum fourth step (25% capacity) of unloading the compressor (1) and opening only the fourth opening / closing valve (20R4).

Further, the compressor (1) is provided with an unloader mechanism (9) for switching the capacity between full load and unload by opening and closing a pilot valve (20Ru). (Cu) is a backflow preventing capillary tube.

Here, the chiller circuit (10) of the chilling unit (B) is provided in the utilization medium circulation portion of the evaporator (4).
The cooling liquid that circulates through is circulated, and the cold heat applied in the condenser (2) in the refrigeration circuit (6) is applied to the cooling liquid by heat exchange in the evaporator (4), and the cooling liquid is transferred. It is designed to cool.

Between the liquid line of the refrigeration circuit (6) and the suction pipe, a liquid injection circuit (by which the liquid refrigerant is injected into the suction pipe by bypassing the pressure reducing mechanism (3) and the evaporator (4) ( 7) is provided, and the liquid injection circuit (7) is provided with a capacity adjusting mechanism (8) for switching the injection amount. The capacity adjusting mechanism (8) includes capillary tubes (CI1), (CI2) and opening / closing valves (20R) having large and small pipe diameters.
Two sets formed by connecting 1) and (20R2) in series are arranged in parallel with each other. That is, each on-off valve (2
By individually opening and closing 0I1) and (20I2),
The injection amount and temperature are variable.

Further, the liquid cooling device is provided with sensors, (HPS1) is a pressure switch for high pressure protection, and (HPS1) is
2) is a pressure switch for high pressure control, (26CH) is a discharge gas overheat protector, (Thd) is a discharge pipe sensor that detects the discharge pipe temperature, and (Thw) is the water temperature Wo at the outlet of the evaporator (4). A chilled water temperature controller (26WL) provided with a temperature sensor (outlet temperature detecting means) for operating the anti-freezing operation which outputs a command signal for anti-icing operation by operating at 3 ± 1 ° C. The signals from the above-mentioned sensors are control signals for controlling the operation of the refrigeration system (A).
It is made possible to input to a printer (not shown). Then, according to the detected value of each of the above sensors by the controller,
It is designed to control the operation of the cooling device.

Here, the control contents according to the first embodiment (corresponding to the invention of claim 1) will be explained based on the flowchart of FIG. 3 and the temperature change diagram of FIG.

When the outlet water temperature Wo becomes equal to or lower than the set temperature Ts during the operation of the refrigeration system (A), in step ST1, the compressor (1) is stopped to be in the thermo-off state (time to in FIG. 4). Next, in step ST2, the count value C of the timer (22) is reset and counting is started, and at the same time, the outlet water temperature Wo at that time is stored as the stop temperature Wm (that is, in the present embodiment, Wm = Ts. Will be).
Next, at step ST3, when the count value C becomes a certain time x seconds (for example, about 30 seconds) or more (time t1 in FIG. 4), the process proceeds to step ST4, at which the outlet water temperature Wo at this time and the above stop are set. The temperature difference Y from the temperature Wm is stored as a reference temperature difference.

Then, in step ST5, the outlet water temperature Wo
And the stop temperature Wm, the reference temperature difference Y, and the predetermined value ΔTs
(For example, a value of about 2 ° C.) and the sum (Wm + Y + ΔTs) are compared, wait until Wo ≧ Wm + Y + ΔTs (time t2 in FIG. 4), then proceed to step ST6 to restart the compressor (1). Let

In the above flow, in accordance with the invention of claim 1, the stop control means (5
1) is configured, the stop temperature storage means (52) is configured by the control of step ST2, the reference temperature difference storage means (53) is configured by the control of step ST4, and the return control means (by the control of steps ST5 and ST6. 54) is configured.

Therefore, in the control of the first embodiment,
As shown in FIG. 4, after the stop of the compressor (1) by the stop control means (51), when a certain time has elapsed, the outlet water temperature Wo becomes substantially equal to the inlet water temperature Wi shown by the broken line in the figure. Then, the reference temperature difference storage means (53) stores the temperature difference between the outlet water temperature Wo and the stop temperature Wm at this time as the reference temperature difference Y, and then the outlet water temperature Wo between the stop temperature Wm and the reference temperature difference Y. Predetermined value Δ than the sum (Wm + Y)
When it becomes higher than Ts, that is, when the change of the outlet water temperature Wo from the stop temperature Wm becomes larger than the reference temperature difference by a predetermined value ΔTs or more, the return control means (54) causes the compressor (1) to operate.
Is controlled to restart.

Here, after a lapse of a certain time after the thermostat is turned off, the outlet water temperature Wo is substantially equal to the inlet water temperature Wi, so the reference temperature difference Y is substantially equal to the temperature difference between the outlet water temperature Wo and the inlet water temperature Wi during operation. .. On the other hand, the temperature difference between the outlet water temperature Wo and the inlet water temperature Wi during operation is substantially constant depending on the model and the type of the heat exchange medium. Therefore, as in the above-described embodiment, when the increase in the outlet water temperature Wo from the stop temperature Wm becomes higher than the reference temperature difference Y by the predetermined value ΔTs, it is determined that the compressor (1) is restarted. Outlet water temperature W when the compressor (1) returns
It is possible to keep o substantially constant, and it is possible to effectively prevent the control from becoming unstable due to the excessive rise in the outlet water temperature Wo when the compressor (1) is restarted.

Next, the control contents of the second embodiment according to the invention of claim 2 will be explained based on the flowchart of FIG.

When the compressor (1) is stopped by the thermo-off command in step SS1 during operation of the refrigeration system, the count value C of the timer is reset and counting is started in step SS2, and at the same time, the outlet water temperature at that time is reset. Wo
Is stored as the stop temperature Wm. Also, step SS3
Then, (ΣΔTn) / n = X (n = 0, 1, ...)
Average value X of the reference temperature difference ΔTn for each thermo-off
Is calculated and the value is stored as the average temperature difference X.

Next, in step SS4, wait until the count value C of the timer reaches x seconds, and then in step SS5,
The temperature difference Y between the outlet water temperature Wo and the stop temperature Wm at that time is calculated as Y = Wo-Wm, and the temperature difference Y is stored as a reference temperature difference, and ΔTn is calculated in step SS6.
= ΔTn-1, ΔTn-1 = ΔTn-2, ... ΔT1 = ΔTo,
After setting ΔTo = Y and updating the memory for calculating the average temperature difference X in the next control, a predetermined numerical value α (α> 1) is set for the reference temperature difference Y and the average temperature difference X in step SS7. ) And the value αX.

If Y ≧ αX is not satisfied, that is, if the rise of the outlet water temperature Wo when x seconds have elapsed after the compressor (1) is stopped is a normal value, the process proceeds to step SS8 and the first embodiment described above is performed. Similarly to the example, when Wo ≧ Wm + Y + ΔTs, the process proceeds to step SS10. On the other hand, the above step SS
If Y ≧ αX in the determination of 7, that is, if the rise of the outlet water temperature Wo is abnormally large when x seconds have elapsed after the compressor (1) was stopped, the rise of the water temperature due to load fluctuations during this period is severe. Therefore, it is determined that the determination of the return timing based on the reference temperature difference Y is not appropriate, and the process proceeds to step SS9, where W
When o ≧ Wm + X + ΔTs, the process proceeds to step SS10. Then, if a predetermined time y minutes (for example, about 2 minutes) have passed since the thermostat was turned off, it remains as it is, and if the predetermined time y minutes has not passed, wait until y minutes have passed, and then proceed to step SS11. Restart the compressor (1).

In the above flow, the average temperature storage means (55) according to the invention of claim 2 is constituted by the control of step SS3, and steps SS7 to SS are carried out.
The control of step SS11 via 9 leads to claim 2
The function of the return control means (54) referred to in the invention is constituted. As in the first embodiment, the stop control means (51) is controlled by the control of step SS1, the stop temperature storage means (52) is controlled by the step SS2, and the reference temperature difference storage means (53) is controlled by the control of step SS5. It is configured.

Further, by the control of step SS10,
The return limiting means (56) according to the invention of claim 3 is constituted.

Therefore, in the control of the second embodiment,
In addition to the control of the first embodiment, when the reference temperature difference Y at the current thermo-off is greater than or equal to a predetermined multiple α of the average value X of the reference temperature differences stored in the average temperature difference storage means (55), it is stopped. When the change of the outlet water temperature Wo from the temperature rises from the average temperature difference X instead of the reference temperature difference Y by a predetermined value ΔTs or more, it is determined to return to the thermo-on. That is, when the inlet water temperature Wi of the evaporator (4) rises due to fluctuations in the heat load of the utilization system during the thermo-off, the outlet water temperature W after a certain period of time has passed since the thermo-off.
When o is abnormally high, when the return timing is judged based on the reference temperature difference Y at that time, a return delay occurs, during which the temperature of the circulating fluid supplied to the utilization system rises excessively, causing deterioration of control performance. At that time, however, by determining the return timing to the thermo-on based on the average temperature difference X, it is possible to eliminate the delay in the return and prevent the circulating fluid temperature from rising excessively.

Further, the return limiting means (56) prohibits the return to the thermo-on until a predetermined time y has elapsed after the thermo-off, so that the inlet water temperature Wi is rapidly reduced after the thermo-off and the compression is immediately performed. It is possible to effectively prevent destabilization of the control state in which the machine (1) returns to start and stop frequently.

Although the chiller unit (B) is used as the utilization system in the above embodiment, the present invention is not limited to this embodiment, and the utilization side heat exchanger is used as a condenser to supply hot water. Alternatively, it can be applied to an air conditioner in which the heat exchange medium is air and the outlet temperature thereof is controlled.

[0038]

According to the first aspect of the present invention, the capacity is controlled according to the outlet temperature of the heat exchanger to be used for heat exchange with the refrigerant in the heat exchanger on the use side. As the operation control device of the refrigeration system, the outlet water temperature when the compressor is stopped is stored as the stop temperature, and the temperature difference between the outlet water temperature and the stop temperature when a certain time has elapsed after the compressor is stopped is set as the reference temperature difference. Remember, then
Since the compressor is restarted when the change in the outlet water temperature from the stop temperature exceeds the reference temperature difference by a predetermined value or more, it is possible to effectively prevent an excessive rise in the outlet water temperature when the compressor is restarted. Therefore, it is possible to stabilize the control.

According to the invention of claim 2, in addition to the invention of claim 1, when the reference temperature difference in the current stop is equal to or more than a predetermined multiple of the average value of the reference temperature differences in the respective stops till then, the stop is performed. Since the compressor is restarted when the change in the outlet temperature from the temperature exceeds the average temperature difference by a predetermined value or more, it is necessary to eliminate the delay in the return due to the rapid change in the inlet temperature. Therefore, it is possible to suppress the deviation of the temperature of the heat exchange medium from the control range.

In the invention of claim 3, the above-mentioned claim 1 or 2
In the invention, since the restart of the compressor is prohibited until a predetermined time elapses after the compressor is stopped, a rapid change to the set value side of the inlet water temperature after the compressor is stopped causes Thus, the destabilization of the control state in which the compressor returns to start and stop frequently is prevented.

[Brief description of drawings]

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

FIG. 2 is a refrigerant pipe system diagram of the cooling device according to the embodiment.

FIG. 3 is a flowchart showing the control contents when the thermostat is stopped according to the first embodiment.

FIG. 4 is a diagram showing a change state of the outlet water temperature when the thermostat is stopped.

FIG. 5 is a flowchart showing the control contents when the thermostat is stopped according to the second embodiment.

[Explanation of symbols]

 1 Compressor 2 Condenser (heat source side heat exchanger) 3 Decompression mechanism 4 Evaporator (use side heat exchanger) 6 Refrigerant circuit 51 Stop control means 52 Stop temperature storage means 53 Reference temperature difference storage means 54 Return control means 55 Average Temperature difference storing means 56 Recovery limiting means Thw2 Outlet temperature detecting means

Claims (3)

[Claims] 1. A compressor (1), a heat source side heat exchanger (2),
In a refrigeration system equipped with a refrigerant circuit (6) in which a decompression mechanism (3) and a usage-side heat exchanger (4) are sequentially connected, a storage device for exchanging heat with a refrigerant in the usage-side heat exchanger (4). Outlet temperature detecting means (Thw
2) and the output of the outlet temperature detection means (Thw2), and a stop control means (51) for controlling to stop the compressor (1) according to the reduction of the required capacity, and the stop control means (51). ), A stop temperature storage means (52) for storing the outlet temperature when the compressor (1) is stopped as a stop temperature, and the outlet temperature detection means when a certain time has elapsed after the compressor (1) was stopped. Reference temperature difference storage means (53) for storing the temperature difference between the detected value of (Thw2) and the stop temperature stored in the stop temperature storage means (52) as a reference temperature difference, and the outlet temperature detection means (Thw2) Is received, the stop temperature storage means (52) and the reference temperature difference storage means (5
From the stored contents of 3), when the change in the outlet temperature from the stop temperature becomes larger than the reference temperature difference by a predetermined value or more during the stop of the compressor (1), the return control means (54) for restarting the compressor (1). ) And an operation control device for a refrigerating machine. 2. The operation control device for a refrigerating apparatus according to claim 1, wherein an average value of the reference temperature differences stored in the reference temperature difference storage means (52) at the time of each stop of the compressor (1) is averaged. An average temperature difference storage means (55) for storing the temperature difference is provided, and the return control means (54) is provided with the reference temperature difference storage means (5).
3) and the stored contents of the average temperature storage means (55), the reference temperature difference at the time of the stop and the average temperature difference are compared, and when the reference temperature difference is greater than a predetermined multiple of the average temperature difference, the stop temperature An operation control device for a refrigeration system, which controls to restart the compressor (1) when a change in outlet temperature exceeds a difference in average temperature by a predetermined value or more. 3. The operation control device for a refrigerating apparatus according to claim 1, wherein after the compressor (1) is stopped, the restart of the compressor (1) is prohibited for a predetermined time period longer than the certain time period. An operation control device for a refrigerating apparatus, comprising: return limiting means (56) for