JPH04222353A - Operation controller for air conditioner - Google Patents

Abstract

PURPOSE:To reduce the frequencies of starts and stops by preventing occurrence of instant overrising of high pressure side pressure and discharged-refrigerant temperature at the time of compressor start during heating operation of an air conditioner. CONSTITUTION:At the time of start of a compressor during heating operation, an initial opening degree of a motor-operated expansion valve 5 is retained small by an initial opening degree control means 40. If the discharged-refrigerant temperature exceeds a prescribed value, the opening degree of the motor- operated expansion valve 5 is increased gradually little by an opening degree increasing control means 51. When a prescribed time period has elapsed after starting, control is transferred by a transfer control means 52 to a normal opening degree control means 53 which controls the opening degree of the motor-operated expansion valve 4 depending on a refrigerant state. By this, first an overrising of high pressure side pressure is restricted, and next, an overrising of the discharged refrigerant temperature is restricted.

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 an air conditioner, and more particularly to a measure for reducing the number of times a compressor starts and stops during heating operation.

0002

[Prior Art] Conventionally, for example, Japanese Patent Application Laid-Open No. 60-185
As disclosed in Publication No. 076, as an operation control device for an air conditioner equipped with a refrigerant circuit in which a compressor, a heat source side heat exchanger, an electric expansion valve, and a user side heat exchanger are sequentially connected, it is possible to control the degree of superheating or The degree of supercooling is detected, and the opening degree of the electric expansion valve is controlled to maintain the degree of superheat at a predetermined value during normal cooling operation and the degree of subcooling during normal heating operation. This is a known technique that attempts to quickly converge to a target opening by controlling the opening of an electric expansion valve to a predetermined opening that is set in advance according to the operation mode.

0003

However, in the above-mentioned conventional device, when the initial opening degree of the electric expansion valve is controlled to be constant during heating operation, there are the following problems. For example, when the initial opening degree of the electric expansion valve is small, as shown in FIG. 7, the high-pressure side pressure Hp changes from xo at the time of startup in a substantially good condition without excessive rise, but the discharge refrigerant temperature T2 As shown in FIG. 8, a peak portion resulting in instantaneous excessive rise occurs at the time of startup (section a at time x1 in the figure), and the air conditioner may be stopped due to discharge pipe protection or the like. On the other hand, when the opening degree of the electric expansion valve is large, the discharge refrigerant temperature T2 changes in an almost favorable condition without showing a peak as shown in Fig. 10, but the high pressure side pressure Hp changes as shown in Fig. 9. A peak portion occurs at startup (portion b at time x2 in the diagram), and the air conditioner may stop due to high pressure cut, etc. In other words, during heating operation, if the opening degree of the electric expansion valve is small, the amount of refrigerant evaporated in the heat exchanger on the user side, that is, the amount of refrigerant circulated to the compressor is small, and the temperature of the discharged refrigerant rises excessively. This is because when the opening degree of the expansion valve is large, the amount of refrigerant circulated is large, but a large amount of refrigerant is discharged before the condensing capacity of the heat source side heat exchanger is insufficient. Since the air conditioner frequently stops operating due to such excessive rises in discharge refrigerant temperature and high-pressure side pressure, the operating limits of the air conditioner are narrowed, and each valve has to be switched or the compressor must be changed each time. Since startup processing is required, there is a problem in that the reliability of the air conditioner is impaired.

[0004] The present invention has been developed in view of the above points, and particularly in FIGS. 8 and 9, the discharge refrigerant temperature peaks at 6 pm after the start of operation.
The peak of high-pressure side pressure appears when a time of about 0 seconds has passed (times xo to x1 in Figure 8), whereas the peak of high pressure side pressure occurs after a time of about 10 seconds has passed (times xo to x2 in Figure 9) after the start of operation. This was done by focusing on the fact that there is a time lag in the high-pressure side pressure that appears when the compressor starts up. The purpose is to reduce the number of times the air conditioner starts and stops by taking measures to suppress excessive rise in the air conditioner, thereby expanding the usage limit and improving reliability.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the solving means of the present invention maintains the opening degree of the electric expansion valve at a small level immediately after the start of operation, and operates the electric expansion valve as the temperature of the discharged refrigerant rises. The purpose is to gradually increase the opening degree of the valve.

Specifically, the measures taken by the invention of claim 1 are as follows:
As shown in Figure 1 (not including the dashed line part), the compressor (1)
, a refrigerant circuit (9) formed by sequentially connecting a heat source side heat exchanger (3), an electric expansion valve (5), and a user side heat exchanger (6);
The present invention is based on an operation control device for an air conditioner including normal opening degree control means (53) for controlling the opening degree of the electric expansion valve (5) according to the state of the refrigerant in the refrigerant circuit (9).

A discharge temperature detection means (Th2) for detecting the temperature of the refrigerant discharged from the compressor (1), and a discharge temperature detection means (Th2) for detecting the temperature of the refrigerant discharged from the compressor (1), and a discharge temperature detection means (Th2) for detecting the temperature of the refrigerant discharged from the compressor (1); After receiving the output of the initial opening degree control means (50) that controls the opening degree to maintain it at a small opening degree and the discharge temperature detection means (Th2), after the compressor (1) is started, the discharge refrigerant temperature is set to a predetermined value. An opening increase control means (51) that controls the opening of the electric expansion valve (5) to gradually increase by small openings from the initial opening when the opening of the electric expansion valve (5) is reached, and a predetermined opening after starting the compressor (1). When the time elapses, the opening degree increase control means (51)
A transition control means (52) is provided to stop the control and shift to the control of the normal opening degree control means (53).

The means taken by the invention of claim 2 is that in the invention of claim 1, evaporation temperature detection means (Thc) for detecting the evaporation temperature of the refrigerant, and condensation temperature detection means (Thc) for detecting the condensation temperature of the refrigerant. The) is provided.

The normal opening control means (53) is connected to the discharge temperature detection means (Th2) and the evaporation temperature detection means (T).
hc) and the output of the condensing temperature detection means (The),
The opening degree of the electric expansion valve (5) is controlled so that the temperature of the discharged refrigerant converges to the optimum temperature of the discharged refrigerant that provides the optimum refrigeration effect determined from the evaporation temperature and condensation temperature of the refrigerant.

0010

[Operation] With the above configuration, in the invention of claim 1, when the compressor (1) is started up during heating operation, the initial opening degree control means (5
0), the initial opening degree of the electric expansion valve (5) is maintained at a predetermined small opening degree, so almost a good change can be obtained without causing an instantaneous excessive rise when the high pressure side pressure rises. . When the discharge refrigerant temperature detected by the discharge temperature detection means (Th2) reaches a predetermined value or higher, the opening degree increase control means (51) slightly decreases the opening degree of the electric expansion valve (5) from the above-mentioned initial opening degree. Since the electric expansion valve (5) is controlled to gradually increase the opening degree, the increase in the discharge refrigerant temperature is suppressed by increasing the opening degree of the electric expansion valve (5). You can get change. Further, when a predetermined period of time has elapsed after startup, the transition control means (52) switches to normal operation using the normal opening degree control means (53), so that the refrigerant state thereafter is maintained appropriately. Therefore, the operation of the air conditioner is prevented from being stopped due to an excessive rise in the high pressure side pressure or the discharge refrigerant temperature, and the number of times the air conditioner starts and stops is reduced, so the operating limit of the air conditioner is expanded and the reliability is improved.

In the invention of claim 2, the normal opening degree control means (
53), the opening degree of the electric expansion valve (5) is controlled so that the discharge refrigerant temperature converges to the optimum temperature that provides the optimum refrigeration effect, so while using an inexpensive constant displacement compressor (1), It becomes possible to configure an efficient air conditioner, and instantaneous excessive increases in the high-pressure side pressure and the discharge refrigerant temperature, which tend to occur when the constant displacement compressor (1) is started, are prevented.

0012

Embodiments Hereinafter, embodiments of the present invention will be described with reference to FIG. 2 and subsequent drawings.

FIG. 2 shows a refrigerant piping system of an air conditioner to which the present invention is applied, in which (1) is a constant displacement compressor, (2)
(3) 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, and (3) is the heat source side heat exchanger that functions as a condenser during cooling operation and as an evaporator during heating operation. An outdoor heat exchanger, (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 (6) is installed indoors. , an indoor heat exchanger (7) is a user-side heat exchanger that functions as an evaporator during cooling operation and as a condenser during heating operation; This is an accumulator for removing refrigerant.

Each of the above-mentioned devices (1) to (7) has refrigerant piping (8
) are successively connected to form a refrigerant circuit (9) that causes heat transfer by circulating the refrigerant. Note that (13) is a supercooling capillary tube installed on the liquid pipe side of the outdoor heat exchanger (3).

[0015] Here, the compressor (1) of the refrigerant circuit (9)
) An oil recovery device (10) for recovering oil in the discharged refrigerant is interposed on the discharge side, and the oil recovery device (10) is connected between the compressor (1) and the accumulator (7). up to the suction pipe of
An oil return passage (11) for returning oil from the oil recovery device (10) to the suction side of the compressor (1) is provided via a flow control valve (12).

Furthermore, in the liquid pipe of the refrigerant circuit (9), the receiver (4) and the electric expansion valve (5) are arranged such that the electric expansion valve (5) is connected to the lower part of the receiver (4), that is, the liquid part. The common path (8a) is arranged in series so as to communicate with the common path (8a).
Between the point (P), which is the upper end of the receiver (4) in a), and the outdoor heat exchanger (3), the refrigerant flows from the outdoor heat exchanger (3) to the receiver (4). The indoor heat exchanger (6) is connected between the point (P) of the common path (8a) and the indoor heat exchanger (6) by the first inflow path (8b) via the first check valve (D1) that allows only the flow of A second inflow path (
8c), while the common path (8c)
The point (Q) which is the other end of the electric expansion valve (5) in a)
) and the point (S) between the first check valve (D1) and the outdoor heat exchanger (3).
3) A third check valve (D3) that allows only the flow of refrigerant to
between the point (Q) of the common path (8a) and the point (R) between the second check valve (D2) and the indoor heat exchanger (6) via the first outflow path (8d). are connected to each other by a second outflow path (8e) via a fourth check valve (D4) that allows only the flow of refrigerant from the electric expansion valve (5) to the indoor heat exchanger (6). Further, between a point (W) on the upstream side of the receiver in the common path (8a) and a point (U) on the upstream side of the fourth check valve (D4) in the second outflow path (8e), Liquid seal prevention bypass path (8f) with capillary tube (C) interposed
is provided to prevent liquid sealing when the compressor (1) is stopped.

[0017] Also, sensors are arranged in the air conditioner, and (Thd) is arranged in the discharge pipe of the compressor (1), and serves as a discharge temperature detection means for detecting the discharge refrigerant temperature T2. The sensor, (Thc) is the outdoor heat exchanger (3
), and during cooling operation, the condensation temperature of the refrigerant,
An external heat exchange sensor (Tha) serving as an evaporation temperature detection means for detecting the evaporation temperature of the refrigerant during heating operation is arranged at the air suction port of the outdoor heat exchanger (3), and an outside temperature sensor (Tha) for detecting the outside air temperature. The) is an internal heat exchange sensor that is placed in the liquid pipe of the indoor heat exchanger (6) and serves as a condensing temperature detection means that detects the evaporation temperature during cooling operation and the condensation temperature during heating operation; (Thr) is the indoor heat exchanger (6) A room temperature sensor located at the air intake port to detect the intake air temperature, (HPS
) is a high-pressure operating pressure switch that operates and abnormally stops when the high-pressure side pressure reaches the upper limit, and (LPS) is a low-pressure operating pressure switch that operates and abnormally stops when the low-pressure side pressure reaches the lower limit. The controller is connected to a controller (not shown) for controlling the operation of the air conditioner so that signals can be input, and the controller controls the operation of each device according to the sensor signals. It is made to be.

In the refrigerant circuit (9), during cooling operation, the liquid refrigerant condensed and liquefied in the outdoor heat exchanger (3) flows from the first flow path (8b) to the common path (8a) and passes through the receiver ( 4) and after being depressurized by the electric expansion valve (5),
It is circulated through the second outlet path (8e), evaporated in the indoor heat exchanger (6), and returned to the compressor (1). Also, during heating operation, the liquid refrigerant condensed and liquefied in the indoor heat exchanger (6) is transferred to the second
It flows from the flow path (8c) to the common path (8a) and flows into the receiver (
4), and after being depressurized by the electric expansion valve (5), it passes through the first outflow path (8d), evaporates in the outdoor heat exchanger (3), and returns to the compressor (1), resulting in circulation.

Here, regarding the control contents at the time of starting the compressor (1) during the heating operation of the air conditioner, the flowchart in FIG. 3 and the time change in the opening degree of the electric expansion valve (5) in FIG. This will be explained based on the diagram. First, in step ST1, the initial opening degree of the electric expansion valve (5) is set to 250 pulses. This electric expansion valve (5) has 500 pulses when fully opened, and this opening degree corresponds to exactly half open. Next, in steps ST2, ST3, and ST4, an outdoor fan (not shown) is installed.
, the four-way selector valve (2), and the compressor (1) are turned on in sequence to start operation (time to in FIG. 4). Then, in step ST5, it is determined whether 3 minutes have elapsed since the start of the compressor (1), and the following start-up control is performed until the 3 minutes have elapsed. That is, in step ST6, the discharge pipe sensor (
The discharge refrigerant temperature T2 detected at Th2) is 70 (℃)
The electric expansion valve (5) is operated by maintaining the opening degree of the electric expansion valve (5) at 250 pulses set in step ST1 until T2>70 (between times to and t1 in FIG. 4).
℃), the process proceeds to step ST7 and the electric expansion valve (5℃) is reached.
) is increased by 2 pulses. Then, this control is repeated for sampling every 2 seconds, and the opening degree of the electric expansion valve (5) is gradually increased from 250 pulses by 2 pulses every 2 seconds (time t1 in FIG. 4).
~ t2), and when 3 minutes have elapsed after startup in the determination in step ST5 (time t2 in FIG. 4), step ST8
and perform normal operation.

In this normal operation, the opening degree of the electric expansion valve (5) is controlled as follows. That is, the evaporation temperature Te of the refrigerant detected by the external heat exchanger sensor (Thc),
From the condensation temperature Tc of the refrigerant detected by the internal heat exchange sensor (The), the formula Tk = 4-1.13Te +
1.72Tc, the optimum temperature Tk that provides the optimum refrigerating effect of the device is calculated, and the opening degree of the electric expansion valve (5) is controlled so that the discharge refrigerant temperature T2 converges to this optimum temperature Tk.

In the above flow, the control in step ST1 constitutes the initial opening control means (50) of the present invention, and the control in step ST7 constitutes the opening increase control means (50).
1) is configured. Further, the transition control means (52) is controlled to transition from step ST5 to step ST8.
is configured, and a normal opening degree control means (53) is configured by the control in step ST8.

Therefore, in the above embodiment, when the compressor (1) is started during heating operation, the initial opening degree control means (50) controls the initial opening degree of the electric expansion valve (5) to a predetermined small opening degree ( 2
50 pulses). At this time, electric expansion valve (5
) is small, so the high pressure side pressure Hp does not cause the instantaneous excessive rise at the time of rise as shown in Fig. 9 above.
As shown in FIG. 5, almost good rise characteristics are exhibited. However, since the initial opening degree of the electric expansion valve (5) is small, the discharge refrigerant temperature T2 tends to rise momentarily at a slightly delayed rise as shown in Fig. 8 above; When the discharge refrigerant temperature T2 detected by the pipe sensor (Th2) reaches a predetermined value (70°C), the opening degree increase control means (51) slightly reduces the opening degree of the electric expansion valve (5) from the above-mentioned initial opening degree. Since it is controlled to gradually increase the opening degree (2 pulses), the increase in the opening degree of the electric expansion valve (5) suppresses the rise in the discharge refrigerant temperature T2 as shown in FIG. Good change characteristics can be obtained without causing instantaneous excessive rise like in No. 8. Furthermore, when a predetermined period of time (3 minutes) has elapsed after startup, the transition control means (52) switches to normal operation using the normal opening control means (53), so that the refrigerant state can be maintained appropriately thereafter. Become. In other words, the shutdown of the air conditioner due to an excessive rise in the high-pressure side pressure Hp or the discharge refrigerant temperature T2 is avoided, and the number of starts and stops is reduced, which expands the operating limits of the air conditioner and improves its reliability. can be achieved.

In particular, as in the above embodiment, the compressor (1)
is a constant capacity type, and the discharge refrigerant temperature T2 is set to the optimum temperature T that provides the optimum refrigerating effect by the normal opening control means (53).
When controlled so as to converge to Therefore, at the time of startup, instantaneous excessive increases in the high-pressure side pressure Hp and the discharge refrigerant temperature T2 as described above tend to occur. Therefore, a significant effect can be obtained by avoiding a shutdown through a series of controls on the opening degree of the electric expansion valve (5) as described above.

[0024]

As explained above, according to the invention of claim 1, as an operation control device for an air conditioner, when the compressor (1) is started during heating operation, the initial opening degree of the electric expansion valve is controlled. In addition to maintaining a small opening, when the discharge refrigerant temperature rises and exceeds a predetermined value, the electric expansion valve is gradually opened in small increments, and returns to normal operation after a predetermined period of time has passed after startup. Therefore, it is possible to prevent the occurrence of instantaneous excessive rises in the high-pressure side pressure and discharge refrigerant temperature, thereby avoiding the shutdown of the air conditioner.Therefore, the operating limit is expanded by reducing the number of times the compressor starts and stops. and reliability can be improved.

According to the invention of claim 2, in the invention of claim 1, the electric expansion valve is configured to converge the temperature of the discharged refrigerant to the optimum temperature of the discharged refrigerant calculated from the evaporation temperature and the condensation temperature during normal operation. Since the opening degree of the
It is now possible to use a constant displacement compressor, and while performing efficient air conditioning through simple control, it is possible to prevent excessive rises in high-pressure side pressure and discharge refrigerant temperature, making it highly effective. .

[Brief explanation of the drawing]

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

FIG. 2 is a refrigerant piping system diagram of the air conditioner according to the embodiment.

FIG. 3 is a flowchart showing the details of compressor startup control.

FIG. 4 is a diagram showing changes over time in the opening degree of the electric expansion valve during startup.

FIG. 5 is a characteristic diagram showing temporal changes in high-pressure side pressure at startup in the example.

FIG. 6 is a characteristic diagram showing temporal changes in discharge refrigerant temperature at startup in the example.

FIG. 7 is a characteristic diagram showing a time change in high pressure side pressure at a small opening degree in a conventional example.

FIG. 8 is a characteristic diagram showing temporal changes in discharge refrigerant temperature at a small opening in a conventional example.

FIG. 9 is a characteristic diagram showing a time change in high pressure side pressure at a large opening degree in a conventional example.

FIG. 10 is a characteristic diagram showing temporal changes in discharge refrigerant temperature at a large opening degree in a conventional example.

[Explanation of symbols]

1 Compressor 3 Outdoor heat exchanger (heat source side heat exchanger) 5
Electric expansion valve 6 Indoor heat exchanger (user side heat exchanger) 9
Refrigerant circuit 50 Initial opening control means 51 Opening increase control means 52 Transition control means 53 Normal opening control means

Claims (2)

[Claims] [Claim 1] Compressor (1), heat source side heat exchanger (3)
, a refrigerant circuit (9) formed by sequentially connecting an electric expansion valve (5) and a user-side heat exchanger (6), and a refrigerant circuit (9) in which the electric expansion valve (5) In the operation control device for an air conditioner, the operation control device includes a normal opening degree control means (53) for controlling the opening degree, and a discharge temperature detection means (Th2) for detecting the temperature of the refrigerant discharged from the compressor (1); an initial opening degree control means (50) that controls the initial opening degree of the electric expansion valve (5) to be maintained at a small opening degree when the compressor (1) in operation is started; and the discharge temperature detection means (Th2). ), after starting the compressor (1), when the discharge refrigerant temperature reaches a predetermined value or more, the opening degree of the electric expansion valve (5) is gradually increased by small opening degrees from the initial opening degree. the opening increase control means (51) to control, and the opening increase control means (51) when a predetermined time has elapsed after starting the compressor (1);
1. An operation control device for an air conditioner, comprising: a transition control means (52) for stopping control of the normal opening degree control means (53) and shifting to control of the normal opening degree control means (53). 2. The operation control device for an air conditioner according to claim 1, comprising evaporation temperature detection means (Thc) for detecting the evaporation temperature of the refrigerant, and condensation temperature detection means (The) for detecting the condensation temperature of the refrigerant. and normal opening control means (5
3) receives the outputs of the discharge temperature detection means (Th2), the evaporation temperature detection means (Thc), and the condensation temperature detection means (The), and determines the discharge refrigerant temperature at the optimum temperature determined from the evaporation temperature and condensation temperature of the refrigerant. An operation control device for an air conditioner that controls the opening degree of an electric expansion valve (5) so that the temperature of the discharged refrigerant converges to the optimum temperature that provides a refrigeration effect.