JP2500522B2 - Refrigeration system operation controller - Google Patents

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 machine, and more particularly to reducing the number of times of starting and stopping of a compressor by repeating thermo-off and restart.

[0002]

2. Description of the Related Art Conventionally, for example, JP-A-60-1850.
As disclosed in Japanese Patent Laid-Open No. 76-76, as an operation control device of a refrigerating apparatus having a refrigerant circuit in which a compressor, a heat source side heat exchanger, an electric expansion valve, and a use side heat exchanger are sequentially connected, the degree of superheat of refrigerant or Detecting the degree of cooling, the degree of superheat during normal cooling operation, while controlling the opening of the electric expansion valve to maintain the degree of supercooling at a predetermined value during normal heating operation, respectively, at the start of operation of the refrigeration system, By controlling the opening of the electric expansion valve to a predetermined opening preset according to the operating mode,
A known technique is to try to achieve a prompt convergence to a target opening.

[0003]

By the way, in the operation control device of the refrigeration system, which controls the opening of the electric expansion valve with the optimum temperature of the discharged refrigerant giving the optimum refrigeration effect as the control target value, In order to protect the compressor from excessive rise in the discharge refrigerant temperature, when the discharge refrigerant temperature reaches or exceeds the specified temperature, the compressor is stopped for a specified time, the so-called thermo-off state is set, and when the specified time elapses, the thermo-on state is established. It is designed to switch to the state and restart the compressor.However, in the operation control device for such a refrigeration system, when the initial opening of the electric expansion valve is set to a constant value as in the conventional device described above, There was a problem.

That is, as shown in FIG. 5, after the initial opening of the electric expansion valve is set to a constant value and the operation is started, the refrigerant circulation amount is reduced due to the accumulation of the refrigerant in the refrigerant circuit during the operation. When insufficient, the discharged refrigerant temperature rises, and the opening degree of the electric expansion valve also increases accordingly, but under the condition that the refrigerant circulation amount is insufficient, it is not possible to suppress the rise of the discharged refrigerant temperature, The refrigerant temperature rises above a predetermined temperature, and the compressor stops thermo-off (time x1 in the figure). Then, after the elapse of a predetermined time, the initial opening of the electric expansion valve is set to a constant value and restarted (time x1 in the figure), and under the condition that the circulation amount of the refrigerant is insufficient, the discharged refrigerant is discharged. The temperature rises again and reaches a predetermined temperature, and the compressor stops thermo-off (time x2 in the figure). Then, after a certain period of time, the process switches to thermo-on and restarts (time x3 in the figure), but immediately the temperature of the discharged refrigerant rises to thermo-off (time x4 in the figure). Will be performed (time x5 or less in the figure). Then, until the discharged refrigerant state reaches a steady state, the compressor may be repeatedly started and stopped due to switching between thermo-on and thermo-off, which may lead to a decrease in operating efficiency and reliability. It was

The present invention has been made in view of the fact that the repetition of thermo-on / thermo-off at the time of starting the compressor as described above is caused by the retention of the refrigerant in any one of the refrigerant circuits. Under such a condition that the refrigerant remains stagnant, it is possible to reduce the number of times of starting and stopping the compressor by improving the efficiency and reliability of the compressor by taking measures to secure the refrigerant circulation amount. .

[0006]

To achieve the above object, the solution means of the present invention is to increase the initial opening degree of the electric expansion valve at the time of restarting more than the initial opening degree at the time of previous starting.

Specifically, the means taken by the invention of claim 1 is, as shown in FIG. 1, a compressor (1), a heat source side heat exchanger (3), an electric expansion valve (5) and a utilization side. It is assumed that the refrigerating apparatus has a refrigerant circuit (9) in which heat exchangers (6) are sequentially connected.

As an operation control device for the refrigeration system,
Initial opening setting means (51) for setting the initial opening of the electric expansion valve (5) to a constant value at the start of operation of the refrigeration system.
And a discharge temperature detecting means (Th2) for detecting the discharge refrigerant temperature
And an opening control means (53) for controlling the opening of the electric expansion valve (5) by receiving the output of the discharge temperature detection means (Th2) and using the optimum temperature of the discharge refrigerant that gives the optimum refrigeration effect as a control target value. ) And the output of the discharge temperature detecting means (Th2), and when the discharge refrigerant temperature reaches or exceeds a predetermined temperature, the operation control means (50) for stopping and restarting the compressor (1) for a predetermined time. ) And shall be provided.

Further, the initial opening degree of the electric expansion valve (5) when the compressor (1) is restarted by the operation control means (50) is changed to be increased by a predetermined opening degree from the initial opening degree at the previous startup. The opening degree increasing means (52) is provided.

[0010]

With the above construction, in the present invention, the initial opening of the electric expansion valve (5) is set to a constant value by the initial opening setting means (51) at the start of operation of the refrigeration system, and then the opening control is performed. The opening degree of the electric expansion valve (5) is controlled by the target value by the means (53) so that the discharged refrigerant temperature converges to the optimum temperature.
At that time, when the refrigerant circulation amount to the compressor (1) becomes insufficient due to the accumulation of the refrigerant in the refrigerant circuit (9) during the operation of the refrigeration system, the discharged refrigerant temperature rises and the target value is accordingly increased. The controlled opening of the electric expansion valve (5) gradually increases,
Since the discharge refrigerant temperature rises rapidly, the opening degree control of the electric expansion valve (5) cannot be sufficiently followed, and the discharge refrigerant temperature exceeds a predetermined temperature. Then, when the operation control means (53) restarts the compressor (1) after stopping it for a predetermined time, the temperature of the discharged refrigerant again becomes equal to or higher than the predetermined temperature, and the temperature rises.
Although there is a risk that the moff, restart, thermo-off, ... Are repeated, in the present invention, the opening degree increasing means (52) causes the operation control means (53) to restart the electric expansion valve (5). Since the initial opening is changed so as to be increased by a predetermined opening from the initial opening at the time of the previous startup, the engine is started in a state in which the refrigerant circulation amount is large. Therefore, the opening of the electric expansion valve (5) against the rise of the discharged refrigerant temperature is opened. The followability of the degree control gradually improves, and thereafter, the rise of the discharge refrigerant temperature is gradually suppressed and converges to a steady state. Therefore, the thermo-off,
Frequent start / stop of the compressor (1) due to repeated restarts, ... Is prevented, deterioration of the air conditioning effect is avoided, and reliability is improved.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.

FIG. 2 shows a refrigerant piping system of an air conditioner to which the present invention is applied. An alternate four-way switching valve, (3) 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, and (4) is a receiver for storing liquid refrigerant. A bar (5) is an electric expansion valve having a function of decompressing the refrigerant and a function of adjusting the flow rate of the refrigerant, and (6) is installed indoors and functions as an evaporator during cooling operation and as a condenser during heating operation. An indoor heat exchanger, which is an exchanger, (7) is an accumulator for removing the liquid refrigerant in the suction refrigerant, which is provided in the suction pipe of the compressor (1).

The above-mentioned devices (1) to (7) are sequentially connected by a refrigerant pipe (8), and a refrigerant circuit (9) is constructed so as to cause heat transfer by circulation of the refrigerant. Incidentally, (13) is a supercooling capillary tube provided on the liquid pipe side of the outdoor heat exchanger (3).

On the discharge side of the compressor (1) of the refrigerant circuit (9), an oil recovery unit (10) for recovering the oil in the discharged refrigerant is provided. (10)
From the compressor to the suction pipe between the compressor (1) and the accumulator (7), an oil return passage (11) for returning the oil of the oil recovery device (10) to the suction side of the compressor (1) has a flow control valve. It is provided through (12).

In addition, in the liquid pipe of the refrigerant circuit (9), the receiver (4) and the electric expansion valve (5) are the lower portion of the receiver (4), that is, the liquid portion. Are arranged in series with the common path (8a) so as to communicate with the common path (8a).
The refrigerant from the outdoor heat exchanger (3) to the receiver (4) is provided between the outdoor heat exchanger (3) and the point (P), which is the upper end of the receiver (4) of a). 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 While being connected by the second inflow passage (8c) via the second check valve (D2) that allows only the flow of the refrigerant from the heat exchanger (6) to the receiver (4), the common passage Point (Q) at the other end of the electric expansion valve (5) of (8a) and the first check valve (D1) -outdoor heat exchanger (3).
A third check valve (D) that allows only the refrigerant to flow from the electric expansion valve (5) to the outdoor heat exchanger (3) between the point (S) and the point (S).
3) via the first outflow path (8d) to the common path (8
From the electric expansion valve (5) to the indoor heat exchanger (6) between the point (Q) in a) and the point (R) between the second check valve (D2) and the indoor heat exchanger (6). The second outflow passages (8e) are connected to each other via the fourth check valve (D4) that allows only the flow of the refrigerant to and from the refrigerant. Also, one point (W) on the receiver upstream side of the common path (8a) and the fourth point of the second outflow path (8e).
A liquid-sealing prevention bypass passage (8f) provided with a capillary tube (C) is provided between the check valve (D4) and a point (U) on the upstream side, and the compressor (1 ) Is designed to prevent liquid sealing when stopped.

Further, the air conditioner is provided with sensors, (Th2) is arranged in the discharge pipe of the compressor (1), a discharge pipe sensor for detecting the discharge pipe temperature, and (Thc) is outdoor. An external heat exchange sensor which is arranged in the liquid pipe of the heat exchanger (3) and detects the condensation temperature of the refrigerant during the cooling operation and the evaporation temperature of the refrigerant during the heating operation, (Tha) is the air intake of the outdoor heat exchanger (3) An outside air temperature sensor placed in the mouth to detect the outside air temperature,
(The) is arranged in the liquid pipe of the indoor heat exchanger (6), an internal heat exchange sensor for detecting the evaporation temperature during the cooling operation and the condensation temperature during the heating operation, and (Thr) is the air inside the indoor heat exchanger (6). A room temperature sensor that is located at the suction port and detects the temperature of the intake air, (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 when the low pressure side pressure reaches the lower limit. A low-pressure operating pressure switch for operating and abnormally stopping, wherein the sensors are connected to a controller (not shown) for controlling the operation of the air conditioner so that signals can be input to the controller. The controller controls the operation of each device according to the signal from the sensor.

In the refrigerant circuit (9), during the cooling operation, the liquid refrigerant condensed and liquefied in the outdoor heat exchanger (3) flows from the first flow passage (8b) to the common passage (8a) and the receiver ( After being stored in 4) and decompressed by the electric expansion valve (5),
The circulation is returned to the compressor (1) by evaporating in the indoor heat exchanger (6) via the second outflow passage (8e). During the heating operation, the liquid refrigerant condensed and liquefied in the indoor heat exchanger (6) is
After flowing from the flow passage (8c) to the common passage (8a), stored in the receiver (4) and decompressed by the electric expansion valve (5),
The circulation is performed by evaporating in the outdoor heat exchanger (3) through the first outflow passage (8d) and returning to the compressor (1).

Here, the control contents during the cooling operation by the controller will be described based on the flowchart of FIG. When the operation of the air conditioner is started, first, at step ST1, the thermo-off count Up is set to an initial value "0", and at step ST2, the electric expansion valve (5) (500
The initial opening Po of the pulse (fully opened) is Po = 25
Set based on 0 + Up x 50 (pulse). That is,
Immediately after the start of operation of the air conditioner, Po = 250 (pulses). Next, steps ST3, ST4 and ST5
Then, the outdoor fan (not shown), the four-way switching valve (2) and the compressor (1) are sequentially turned on, and in step ST6, the discharge refrigerant temperature T2 detected by the discharge pipe sensor (Th2) is input. Then, in step ST7, the opening P of the electric expansion valve (5) is controlled to a target value. That is, the internal heat exchange sensor (The)
From the evaporation temperature Te of the refrigerant detected by the above and the condensation temperature Tc of the refrigerant detected by the external heat exchange sensor (Thc),
Based on Tk = 4-1.13Te + 1.72Tc, the optimum temperature Tk that gives the optimum refrigerating effect of the device is calculated, and the electric expansion valve (5) is opened so that the discharged refrigerant temperature T2 converges to this optimum temperature Tk. Control the degree P.

Then, while the target value control of the opening P of the electric expansion valve (5) is being performed, the discharge refrigerant temperature T2 rises, and the discharge refrigerant temperature T2 is determined by the determination in step ST8.
If the temperature exceeds the set value of 135 ° C for 100 seconds, the process proceeds to step ST9 to protect the compressor (1) and so on, and the number of thermo-offs Up after the start of operation of the air conditioner Up
Is added by 1, and in step ST10, the compressor (1)
After stopping the thermostat, in step ST11,
After waiting 3 minutes after the power-off, the process returns to step ST2.

In the above flow, step ST10,
The operation control means (50) of the present invention is configured by the control of ST11 to steps ST3, ST4, ST5, and the initial opening setting means (5) is controlled by the control of steps ST1 and ST2.
1) is configured. Also, steps ST9 and ST
The opening degree increasing means (52) is configured by the control of step 2, and the opening degree control means (53) is configured by the control of step ST7.

Therefore, in the above embodiment, when the operation of the air conditioner is started, the initial opening degree setting means (51) sets the initial opening degree Po of the electric expansion valve (5) to a constant value (205 pulses).
After that, the opening degree control means (53) controls the opening degree P of the electric expansion valve (5) by the target value so that the discharged refrigerant temperature T2 converges to the optimum temperature Tk. At that time,
As shown in, the refrigerant circuit (9) during operation of the air conditioner
When the refrigerant circulation amount to the compressor (1) becomes insufficient due to the accumulation of refrigerant in the inside, the discharged refrigerant temperature T2 rises, and the opening P of the electric expansion valve (5) whose target value is controlled accordingly. Gradually increases, but since the discharge refrigerant temperature T2 rises sharply,
The control of the opening degree P of the electric expansion valve (5) may not be in time. After that, when the opening degree P of the electric expansion valve (5) reaches an allowable maximum value (for example, an opening degree of about 480 pulses), the rise of the discharge refrigerant temperature T2 cannot be suppressed, and the predetermined temperature (thermo-off setting Value 135 ° C.) (time to in the figure). Then, the operation control means (53) controls to restart the compressor (1) after maintaining it in a so-called thermo-off state in which the compressor (1) is stopped for a predetermined time (3 minutes). However, in a situation where the circulation amount of the refrigerant is insufficient, after restarting the compressor (1), the initial opening degree Po of the electric expansion valve (5) is set to a constant value to continue the operation. However, the discharge refrigerant temperature T2 again exceeds the thermo-off set value (135 ° C), and thermo-off, restart, thermo-off, etc. are repeated again, which not only impairs the air conditioning effect but also compresses it. Frequent start and stop of the machine (1) may impair reliability. In particular, as in the above embodiment, the constant capacity type compressor (1) is used, and the discharge refrigerant temperature T
Adjusting the opening of the electric expansion valve (5) using 2 as a control index has the advantage that a high air conditioning effect can be obtained with a simple configuration, but on the other hand, the capacity of the compressor (1) is fixed. There is a possibility that the excessive rise of the discharge refrigerant temperature T2 cannot be suppressed.

Here, in the above embodiment, the opening degree increasing means (52) causes the initial opening degree Po of the electric expansion valve (5) at the time of restarting by the operation control means (53) to be the initial opening degree at the previous starting time. It is changed so as to increase by a predetermined opening (50 pulses). That is, as shown in FIG. 4, after the initial opening Po is increased to 300 pulses and restarted at time t1, the discharge refrigerant temperature T2 rises again and exceeds the thermo-off set value (135 ° C.) (see FIG. At the middle time t2), when the thermostat is turned off, at the next restart (time t3 in the figure), the initial opening degree Po of the electric expansion valve (5) is set to 350 pulses. Therefore, such an electric expansion valve (5)
Since the operation is started from a state in which the circulation amount of the refrigerant is secured to some extent by changing the initial opening Po of the above, the followability of the opening control of the electric expansion valve (5) by the opening control means (53) is re-established. It becomes better each time it starts up, and then the discharged refrigerant temperature T2
The rise of is gradually suppressed and converges to a steady state. Therefore, frequent start / stop of the compressor (1) due to repeated thermo-off, restart, ... Is prevented, deterioration of the air conditioning effect can be avoided, and reliability can be improved.

Although the cooling operation has been described in the above embodiment, it goes without saying that the present invention can be applied not only to the cooling operation but also to the heating operation.

[0024]

As described above, according to the operation control device for the refrigeration system of the present invention, the discharge refrigerant temperature is optimized after the initial opening of the electric expansion valve is set to a constant value at the start of the operation of the refrigeration system. The electric expansion valve opening is controlled to a target value so that it converges to the temperature, and if the discharge refrigerant temperature rises above a predetermined temperature during operation of the refrigeration system, the compressor is stopped after thermostating for a predetermined time and then restarted. At the same time, the initial opening of the electric expansion valve at the time of restart is set to be larger than the initial opening at the previous startup by a predetermined amount, so that the discharge refrigerant temperature rises due to insufficient refrigerant circulation and the compressor is supported. -Even if the power-off is stopped, it is possible to prevent the process of restarting and the power-off after that being repeated many times, and to improve the air conditioning effect and reliability by reducing the number of times the compressor is started and stopped. You can

[Brief description of drawings]

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

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

FIG. 3 is a flowchart showing the control contents of the controller.

FIG. 4 is a time change diagram of a discharged refrigerant temperature and an electric expansion valve opening degree in the embodiment.

FIG. 5 is a time change diagram of discharged refrigerant temperature and electric expansion valve 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 (Use Side Heat Exchanger) 9 Refrigerant Circuit 50 Operation Control Means 51 Initial Opening Setting Means 52 Opening Increasing Means 53 Opening degree control means Th2 discharge pipe sensor (discharge temperature detection means)

Claims (1)

(57) [Claims] 1. A compressor (1), a heat source side heat exchanger (3),
In a refrigeration system provided with a refrigerant circuit (9) in which an electric expansion valve (5) and a utilization side heat exchanger (6) are sequentially connected, the electric expansion valve (5) is initially opened at the start of operation of the refrigeration system. Opening degree setting means (51) for setting the degree to a constant value
And a discharge temperature detecting means (Th2) for detecting the discharge refrigerant temperature
And an opening control means (53) for controlling the opening of the electric expansion valve (5) by receiving the output of the discharge temperature detection means (Th2) and using the optimum temperature of the discharge refrigerant that gives the optimum refrigeration effect as a control target value. ) And the output of the discharge temperature detecting means (Th2), and when the discharge refrigerant temperature reaches or exceeds a predetermined temperature, the compressor (1) is controlled to stop after thermostating for a predetermined time and then restart. And a compressor (1) by the operation control means (50).
Of the electric expansion valve (5) at the time of restarting the vehicle, the refrigeration apparatus comprising opening degree increasing means (52) for changing the initial opening degree by a predetermined amount from the initial opening degree at the previous startup. Operation control device.