JPH0452461A - Operation controller for air conditioner - Google Patents

Abstract

PURPOSE:To prevent hunting and contrive higher control performance by providing a setting means for making such a setting that the interval between operations of an electrically operated expansion valve by an opening-controlling means is made to be longer as the length of pipings for connection between an exterior unit and an interior unit is larger. CONSTITUTION:Where the length of pipings 8g, 8h for connection between an exterior unit A and an interior unit B is large, due to the conditions for installation of an air conditioner, and the interval between operations of an electrically operated expansion valve 5 is short in relation to the period of time required for a change in a refrigerant, there is a possibility that hunting may occur in control. In such a situation, a setting means (SWpls) is operated to make such a setting that the interval between operations of the expansion valve 5 by an opening-controlling means 51 is made to be longer. As a result, the operation of the expansion valve 5 is controlled at suitable intervals according to the period of time required for a change in the refrigerant. Thus, it is possible to prevent the hunting, while maintaining good follow-up characteristics of control.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an operation control device for an air conditioner, and particularly to measures for improving control performance.

(Prior Art) Conventionally, as disclosed in, for example, Japanese Unexamined Patent Publication No. 63-32257, there has been an air conditioner equipped with a refrigerant circuit in which a compressor, a heat source side heat exchanger, an electric expansion valve, and an evaporator are sequentially connected. , the output frequency of the inverter that adjusts the operating capacity of the compressor is detected at a fixed sampling period, and the opening degree of the electric expansion valve is adjusted according to the value of the output frequency. It is a known technique to maintain the dryness of the suction refrigerant within an appropriate range by changing the opening degree of the expansion valve from the controlled opening degree, thereby improving the air conditioning capacity.

(Problems to be Solved by the Invention) By the way, in so-called separate air conditioners that are separated into an outdoor unit and an indoor unit, electric When trying to change the opening of the expansion valve,
The opening degree of the electric expansion valve is adjusted according to changes in operating conditions.
As a result, state quantities such as the temperature, pressure, and degree of superheat of the refrigerant change, but there is a predetermined time delay depending on the length of the piping before a change in the refrigerant state appears due to the adjustment of the opening degree.

That is, for example, when the length of the connecting pipe between the outdoor unit and the indoor unit is short, even if the air conditioner is equipped with a refrigerant circuit that circulates the refrigerant in 1 to 2 minutes, the length of the connecting pipe is about 50 m. Sometimes, the time required for the refrigerant to circulate through the refrigerant circuit reaches 3-4 minutes. Therefore, the time required for a change in the state of the refrigerant to appear also changes accordingly.

However, when the operating state is detected at a fixed sampling time and the opening of the electric expansion valve is controlled accordingly, as in the conventional system described above, the opening of the electric expansion valve is longer than the time required for a change in the refrigerant to appear. It may be possible to control the degree first.

In that case, the state quantity of the refrigerant repeatedly exceeds the control target point in order to further change the opening degree even though the influence of the change in the opening degree of the electric expansion valve has not yet appeared.
There is a possibility that a so-called hunting condition may occur.

On the other hand, the length of the connecting piping of the air conditioner changes depending on the situation at the site, such as the building where the air conditioner is installed. Therefore, in order to prevent the above-mentioned control failures, it is conceivable to set the operation interval in advance to correspond to the longest possible connection piping length; however, conversely,
If the operating interval of the electric expansion valve is too long relative to the refrigerant change time, there is a risk that control followability may deteriorate.

The present invention has been made in view of the above, and its purpose is to provide a means for changing the operation interval for controlling the opening degree of the electric expansion valve depending on the mounting condition of the air conditioner. By doing so, it is possible to prevent hunting without causing deterioration in followability of control, thereby improving control performance.

(Means for solving the problem) In order to achieve the above object, the first means for solving the problem is as shown in FIG. ), electric expansion valve (5) and user-side heat exchanger (
6), and a refrigerant circuit (9) formed by sequentially connecting the outdoor unit (A) and the outdoor unit) (A), and a connecting pipe (9) to the outdoor unit (A).
Indoor unit (B) connected via (8g) and (8h)
).

As an operation control device for the air conditioner, the opening control means (51A) controls the opening degree of the electric expansion valve (5) to increase or decrease at predetermined operation intervals in accordance with changes in the operating state during operation of the air conditioner. ), and the longer the length of the connecting pipe (8g), (8h) between the outdoor unit (A) and the indoor unit (B), the more the electric expansion valve (5) is controlled by the opening control means (51A). This configuration includes a setting means (SWpls) for setting the operation interval to be longer.

The second solution, as shown in FIG. 1 (including the broken line portion), is based on an air conditioner similar to the first solution.

As an operation control device for the air conditioner, there is a discharge pipe temperature detection means (T h2) that detects the discharge pipe temperature, and an output of the discharge pipe temperature detection means (T h2) is received to adjust the discharge pipe temperature to an appropriate value. an opening degree control means (51B) for controlling the opening degree of the electric expansion valve (5) at predetermined operation intervals so that the electric expansion valve (5)
Connection piping (8g) between the outdoor unit (A) and the indoor unit (B).

The longer the length of (8h), the more the opening control means (51B)
This configuration includes a setting means (SWpls) for setting the operation interval of the electric expansion valve (5) to be longer.

(Function) With the above configuration, in the invention of claim (1), during operation of the air conditioner, the opening degree control means (51A) controls the opening degree of the electric expansion valve (5) to increase or decrease at a predetermined operation interval. The temperature, pressure, degree of superheat, etc. of the refrigerant are controlled.

In that case, if the length of the connecting pipes (8g) and (8h) between the outdoor unit (A) and the indoor unit (B) changes depending on the conditions at the installation site of the air conditioner, the refrigerant circuit (9) may The time required for refrigerant circulation varies, especially for connecting pipes (8g).

If the length of (8h) is long and the operation interval of the electric expansion valve (5) is short relative to the time required for changing the refrigerant, there is a risk of control hunting; however, in the present invention, the setting means (SWpls) , connecting pipe (8g), (8h)
The longer the length, the longer the operation interval of the electric expansion valve (5) is set, so the operation of the electric expansion valve (5) is controlled at appropriate intervals corresponding to the time required for changing the refrigerant. Therefore, hunting can be prevented while maintaining good control followability.

In the invention of claim (2), the electric expansion valve (5) is controlled by the opening control means (51B) so that the discharge pipe temperature detected by the discharge pipe temperature detection means (Th2) becomes an appropriate value of the discharge pipe temperature.
) is controlled, and the capacity of the utilization side heat exchanger (6) is controlled.

In that case, the refrigerant state changes due to the change in the opening degree of the electric expansion valve (5), and the discharge pipe temperature changes; There is a predetermined time delay for this to appear, especially when connecting piping (8g) between the outdoor unit (A) and the indoor unit (B)
, (8h) is long, the time delay is large.

Here, in the present invention, the operation interval of the electric expansion valve (5) is set to be lengthened according to the length of the connecting pipe (8g), (8h) by the same effect as the invention of claim (1) above. Therefore, the capacity of the utilization side heat exchanger (6) can be controlled to an appropriate value without causing control hunting.

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

FIG. 2 shows a refrigerant piping system of an air conditioner to which the present invention is applied, and has a so-called separate structure in which one indoor unit (B) is connected to an outdoor unit (A). In the above outdoor unit (A), (1) is a compressor, (2) is a four-way switching valve that switches as shown in the solid line in the figure during cooling operation and as shown in the broken line in the figure during heating operation, (3)
) is an outdoor heat exchanger that is a heat source side heat exchanger that functions as a condenser during cooling operation and as an evaporator during heating operation;
(4) is a receiver for storing liquid refrigerant, (5) is an electric expansion valve that has a refrigerant pressure reduction function and a refrigerant flow rate adjustment function, and (7) is installed in the suction pipe of the compressor (1). , an accumulator for removing liquid refrigerant in the suction refrigerant, and each of the above-mentioned devices is sequentially connected by refrigerant piping (8).

Further, in the indoor unit (B), (6) is an indoor heat exchanger that is a user-side heat exchanger that functions as an evaporator during cooling operation and as a condenser during heating operation,
The devices (1) to (7) of the outdoor unit (A) and the indoor unit (B) are sequentially connected by refrigerant piping (8), and the refrigerant circuit ( 9) is configured.

And between the outdoor unit (A) and the indoor unit (B) are the connecting pipes (8g) and (8h) of the refrigerant pipe (8).
connected by. Note that (14) and (,14) are manual shutoff valves provided at the outlet of the outdoor unit (A).

An oil recovery device (10) for recovering oil in the discharged refrigerant is interposed on the discharge side of the compressor (1) of the refrigerant circuit (9). Compressor (1)
- Oil skimmer (1) up to the suction pipe between the accumulator (7)
An oil return passage (11) is provided for returning the oil from the compressor (1) to the suction side of the compressor (1). This oil return passage (11) is provided with an on-off valve (12) that opens and closes the passage, and while the on-off valve (12) is normally closed, the compression II (1) is activated. An oil collector (10) is installed on the suction side of the compressor (1), and is opened under predetermined control at times.
It is designed to return some of the oil and discharged refrigerant.

Further, in the liquid pipe of the refrigerant circuit (9), the receiver (4) and the electric expansion valve (5) are connected to a common path (
8a), and between the point (P) which is the upper end of the receiver (4) of the common path (8a) and the outdoor heat exchanger (3), there is a connection between the outdoor heat exchanger (3) and the receiver (4) side. The first inflow path (8
According to b), a second check valve (22) is installed between the point (P) of the common path (8a) and the indoor heat exchanger (6), which allows the refrigerant to flow only to the receiver (4) side. through the second inflow channel (
8c), while the common path (8c)
A point (Q) which is the end of the electric expansion valve (5) side of a) and a point (Q) between the first check valve (21) and the outdoor heat exchanger (3)
S) means the first capillary tube (C1).
The outflow path (8d) allows the above point (Q) of the common path (8a)
and the point (R) between the second check valve (22) and the indoor heat exchanger (6) are connected to each other by a second outflow path (8e) via a second capillary tube (C2). .

That is, during cooling operation, the liquid refrigerant condensed and liquefied in the outdoor heat exchanger (3) passes through the first check valve (21) and is stored in the receiver (4), and then flows through the electric expansion valve (5) and the second capillary. After being depressurized in the tube (C2), the indoor heat exchanger (6
) and return to the compressor (1), while during heating operation, the liquid refrigerant condensed and liquefied in the indoor heat exchanger (6) passes through the second check valve (22) and returns to the receiver (4). is stored in the electric expansion valve (5) and the first capillary tube (C
]), is evaporated in an outdoor heat exchanger (3), and is circulated back to the compressor (1).

In addition, (8f) is a liquid seal prevention bypass path provided in the first inflow path (8b) between point CP) and point (S) by bypassing the first check valve (21). A third capillary tube (C3) for reducing the pressure of the refrigerant is interposed in the liquid seal prevention bypass path (8f).

In addition, sensors are installed in the air conditioner (
Th2) is a discharge pipe sensor arranged in the discharge pipe of the compressor (1) and serves as a discharge pipe temperature detection means for detecting the discharge pipe temperature T2, and (The) is arranged in the liquid pipe of the outdoor heat exchanger (3). An outdoor liquid pipe sensor (T ha
) is placed at the air inlet of the outdoor heat exchanger (3) to detect the outside air temperature, and (The) is placed at the liquid pipe of the indoor heat exchanger (6) to detect the evaporation temperature during cooling operation. , an indoor liquid pipe sensor that detects condensation temperature during heating operation;
(T hr) is an indoor suction sensor that is placed at the air suction port of the indoor heat exchanger (6) and detects the temperature of the suction air, and each of the above sensors is connected to a controller ( (not shown) so that signals can be input, and the controller controls the operation of each device according to the signals from the sensor.

Here, the opening degree control of the electric expansion valve (5) during cooling operation by the controller will be explained based on FIG. 3. FIG. 3 shows a measurement flag F pis which is a timer counter for determining the operation interval of the electric expansion valve (5).
(SWpls) is placed on the control panel of the air conditioner, and connects the connecting pipes (8g) and (8h) between the outdoor unit (A) and the indoor unit (B).
When the length of the connecting pipe is less than a predetermined value (for example, about 50 m on one side), the terminal is set to the "0" side (short time side), and when the length of the connecting pipe exceeds the predetermined value, the terminal is set to the "1" side (long time side). This is a dip switch (SWpls) for changing the valve time constant. This dip switch (SWp
ls) is set to the short-time side terminal "0", in step S1, the measurement flag F p! While determining whether or not the time value tpis of the integration timer for s has reached the first time constant "10 seconds" on the short time side, the dip switch (SWpls) is set to the terminal "1" on the long time side. If it has been set, in step S2, the timer's clock value t
It is determined whether or not pls has reached the second time constant "20 seconds" on the long-term side. When each time constant is reached, the process proceeds to step S3, and the measurement flag F pls is set to indicate memory overflow when the valve is not operating. It is determined whether the prevention threshold "20" has been exceeded, and if it has not been exceeded, the measurement flag F pls is integrated in step S4, and if the measurement flag F pis exceeds the threshold "20", the integration is performed. Without doing so, the process proceeds to step S5 and resets the time value tpls of the timer.

Next, FIG. 4 shows the electric expansion valve (5) based on the discharge pipe temperature T2.
) is an example showing a part of the opening degree control of step sho.
Then, it is determined whether the temperature difference ΔT2 between the discharge pipe temperature T2 detected by the discharge pipe sensor (T h2) and the optimum value Tk of the discharge pipe temperature T2 determined based on a predetermined formula from the state of the refrigerant is positive. , if it is not positive, it is determined that the opening degree of the electric expansion valve (5) is too large, and in step SI+, the heat exchange sensor (T
It is determined whether or not the condensing temperature Tc detected in he) is falling, and if it is not falling, in step SI2, it is determined whether or not Fpls≦4 for the measurement flag Fpls, that is, it corresponds to a predetermined operation interval. Determine whether or not the set value "4" has been exceeded, and determine the Fpl when the set value "4" has been exceeded.
When s>4, the process proceeds to step S13 and the electric expansion valve (5) is closed to a larger opening degree.

On the other hand, if the condensing temperature Tc is decreasing or F pls≦4 in the determination in step Sl+, the process proceeds to the next control without changing the opening degree of the electric expansion valve (5).

On the other hand, when the temperature difference ΔT2 between the discharge pipe temperature T2 and the optimum value Tk is positive in the determination in step SIO, it is determined that the opening degree of the electric expansion valve (5) is small, and in step S14, the temperature difference ΔT2 It is determined whether or not F is descending, and if it is not descending, the process proceeds to step SI5, and the measurement flag F is further set.
It is determined whether or not pis is "6" or less, and if it is not "6" or less, the electric expansion valve (5) is opened to a medium degree in step S+6. Note that step S14. With S+5 discrimination,
When the temperature difference ΔT2 is not decreasing and when the measurement flag F pis is "6" or less, the control in step 516 is not performed and the process proceeds to the next control.

In the above flow, the control in step S10""S+6 constitutes an opening degree control means (51A) that controls the opening degree of the electric expansion valve (5) to increase or decrease at predetermined operation intervals.

In particular, the above embodiment corresponds to the invention of claim (a), and the control in step 5IO=SI6 is based on the output of the discharge pipe sensor (discharge pipe temperature detection means) (Th2).
The electric expansion valve (5
) at predetermined operation intervals.
This corresponds to control 1B).

The operation interval of the electric expansion valve (5) controlled by the opening control means (51) is "4" (step 512) or "6" with respect to the integrated value of the measurement flag F pls.
(Step 515), and the unit "1" of this measurement flag F pls means that the time value t pls of the integration timer of the measurement flag F pls is the predetermined 1st. This value is accumulated when the second time constant 10 (seconds) or 20 (seconds) has elapsed, and is switched by the valve time constant switching dip switch (SWpls) (step S1 or S2). That is, the operation interval of the control in step S+3 is 40 seconds when the time constant changeover switch is switched to the first time constant 10 (seconds) side, and the dip switch (SWpls) is switched to the second time constant 2 (seconds).
When switched to the 0 (second) side, the time becomes 80 seconds. Further, the operation interval of the control in step S16 becomes 1 minute when the dip switch (SWIs) is switched to the first time constant 10 (seconds) side, and the operation interval of the dip switch (SWpls) becomes 1 minute.
) is switched to the second time constant 20 (seconds) side, 2
It will be a minute. And this dip switch (SWpls
) is the first time, which is the shortest time, depending on whether the length of the connecting pipe between the outdoor unit (A) and the indoor unit (B) is longer than a predetermined value. The first time constant is switched to a constant of 10 seconds) and a first time constant of 20 seconds, which is a longer time constant. Therefore, the dip switch for changing the valve time constant (
SWpls), a setting means is configured to set the operation interval of the electric expansion valve (5) by the opening control means (1) to be longer as the length of the connecting pipe (8g), (8h) is longer. .

Therefore, in the invention of claim (1), when the air conditioner is operating, the opening control means (51A) controls the opening degree of the electric expansion valve (5) to increase or decrease according to changes in the operating state of the air conditioner. temperature and pressure of the refrigerant.

Conditions such as the degree of superheating are adjusted appropriately. At that time, in so-called separate type air conditioners that are separated into an outdoor unit (A) and an indoor unit (B), the length of the connecting piping between the outdoor unit (A) and the indoor unit (B) is long. As a result, the length of the circulation path of the refrigerant circuit (9) becomes long, and it takes a long time until the state of the refrigerant, such as the temperature, changes due to the change in the opening degree of the electric expansion valve (5).

Therefore, after changing the opening degree of the electric expansion valve (5),
If the opening degree is changed before a change in the refrigerant appears, there is a risk that the control state will become unstable, such as hunting. On the other hand, if the operation interval of the electric expansion valve (5) is too long, control followability will deteriorate. However, such a connecting pipe (8g).

The length (8 h) depends on the conditions at the site where the air conditioner is installed. Therefore, like the conventional one, the electric expansion valve (5)
If the opening degree of the connecting pipe is controlled, it will not be possible to solve the problem of control based on the difference in the length of the connecting piping.

In contrast, in the present invention, the valve time constant switching dip switch (setting means) (SWpls) is used to set the operation interval of the electric expansion valve (5) to be longer depending on the length of the connecting pipe. That is, in the above embodiment, when installing the air conditioner, the basic time constant is set to the first time constant 10.
(seconds) or second time constant 20 (seconds)), the operation interval for controlling the opening of the electric expansion valve (5) by the opening control means (51) corresponds to the time required for the change in refrigerant. Therefore, hunting can be effectively prevented without deteriorating control followability. Therefore, it is possible to improve the 11m performance.

In addition, in the above embodiment, the discharge pipe temperature T2 was used as a parameter for controlling the opening degree of the electric expansion valve (5), but the present invention is not limited to such embodiment, and for example, It can also be applied to cases where so-called constant superheat degree control is performed, in which the suction superheat degree is detected and the value is converged to a predetermined target value.

In the invention of claim (2), as in the above embodiment, the opening degree control means (51B) adjusts the discharge pipe temperature T2 to the appropriate value Tk.
The opening degree of the electric expansion valve (5) is controlled so that the capacity of the utilization side heat exchanger (6) is controlled.

In that case, the refrigerant state changes due to the change in the opening degree of the electric expansion valve (5), and the discharge pipe temperature T2 changes.
There is a predetermined time delay before the effect of changing the opening degree of the electric expansion valve (5) appears as a change in the discharge pipe temperature T2. ).

If the length of (8h) is long, the time delay is large.

Here, in the present invention, the operation interval of the electric expansion valve (5) is set to be lengthened according to the lengths of the connecting pipes (8g) and (8h) by the same effect as the invention of claim (1) above. Therefore, the capacity of the utilization side heat exchanger (6) can be controlled to an appropriate value without causing control hunting. That is, the effect of the invention of claim (1) above can be obtained.

In the above embodiment, the dip switch (SWpls
), the two first . First time constant 10 (seconds) and 20
(seconds), the present invention is not limited to this embodiment, and can be set to be linearly variable by using three or more time constants or a volume.

Further, in the above embodiment, the electric expansion valve (5) is arranged on the outdoor unit (A) side, but it goes without saying that the electric expansion valve (5) can also be applied to one arranged on the indoor unit (B) side.

Furthermore, the present invention can be applied to a so-called multi-type air conditioner in which a plurality of indoor units are connected to one outdoor unit, and the control parameter of the opening control means (51) is the discharge pipe temperature T2 in the above embodiment. The temperature is not limited to , and may be the degree of superheating, the evaporation temperature, or the like.

(Effects of the Invention) As described above, according to the present invention, as an operation control device for an air conditioner in which an outdoor unit and an indoor unit are connected by a connecting pipe, changes in the operating state of the air conditioner can be realized. In addition to controlling the opening degree of the electric expansion valve to increase or decrease according to By adjusting the opening degree of the electric expansion valve in consideration of the delay in refrigerant state change relative to control caused by You can improve your performance.

In the invention of claim (2), when the discharge pipe temperature is detected and the opening degree of the electric expansion valve is controlled to make the discharge pipe temperature an appropriate value, the electric expansion valve similar to the invention of claim (1) is used. Since the operation interval of the valve is set, it is possible to properly maintain the capacity of the heat exchanger on the user side without causing hunting in response to changes in the discharge pipe temperature. ) can make the invention more effective.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention. Figure 2 and the following diagrams show embodiments of the present invention; Figure 2 is a refrigerant piping system diagram showing the overall configuration of an air conditioner; Figures 3 and 4;
The figures show the contents of control by the controller, and Fig. 3 is a flowchart showing a part of the measurement flag integration control, and Fig. 4 is a part of the opening degree control based on the discharge pipe temperature of the electric expansion valve. 1 Compressor 3 Outdoor heat exchanger (heat source side heat exchanger) 5 Electric expansion valve 6 Indoor heat exchanger (user side heat exchanger) 8g, 8h Connecting pipe 51 Opening control means A Outdoor unit B Indoor unit 5Wpls Deep Switch (setting means) Th2 Discharge pipe sensor (discharge pipe temperature detection means) 3rd section

Claims (2)

[Claims] (1) A refrigerant circuit (9) formed by sequentially connecting a compressor (1), a heat source side heat exchanger (3), an electric expansion valve (5), and a user side heat exchanger (6), and an outdoor unit In an air conditioner that is separated into (A) and an indoor unit (B) that is connected to the outdoor unit (A) via connecting pipes (8g) and (8h), when the air conditioner is operated, an opening control means (51A) for controlling the opening degree of the electric expansion valve (5) to increase or decrease at predetermined operation intervals according to changes in the state; Connecting piping (8g), (8h
) and a setting means (SWpls) for setting the operation interval of the electric expansion valve (5) by the opening degree control means (51A) to be longer as the length of the air conditioner becomes longer. Control device. (2) A refrigerant circuit (9) formed by sequentially connecting a compressor (1), a heat source side heat exchanger (3), an electric expansion valve (5), and a user side heat exchanger (6), and an outdoor unit In an air conditioner separated into (A) and an indoor unit (B) connected to the outdoor unit (A) via connecting pipes (8g) and (8h), a discharge pipe for detecting the temperature of the discharge pipe. In response to the outputs of the temperature detection means (Th2) and the discharge pipe temperature detection means (Th2), the opening degree of the electric expansion valve (5) is controlled at predetermined operation intervals so that the discharge pipe temperature becomes an appropriate value. The longer the length of the connecting pipes (8g) and (8h) between the opening control means (51B) and the outdoor unit (A) and the indoor unit (B), the more electrically controlled the opening control means (51B) becomes. Setting means (S) for setting the operation interval of the expansion valve (5) to be longer;
An operation control device for an air conditioner, characterized by comprising: