JPS63163748A - Method of controlling expansion valve in air conditioner - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a method for controlling the opening of an expansion valve in an air conditioner using an expansion valve as a pressure reducer.

<Prior Art> FIG. 3 is a diagram of a refrigeration cycle used in a general air conditioner. In FIG. 3, l is a compressor,
The operation is controlled by an inverter circuit 4 connected to an AC power source 2 via a converter 3. 5 is a four-way switching valve that switches the direction of refrigerant discharged from the compressor 1. 6 is an indoor heat exchanger, 7 is an outdoor heat exchanger, and 8 is an expansion valve as a pressure reducer.

Figure 4 shows a control circuit for a typical air conditioner.

(The same parts as in Fig. 3 are given the same reference numerals.)
In the figure, 9 is an indoor control circuit, 10 is an outdoor control circuit, and both control circuits 9. ! 0 is a power line II so that both are supplied with power by an AC power source 2.

12. I3 is a relay switch interposed in this power line 12, and the outdoor control circuit 10 is turned on from ON and 0FFK of this relay switch 13.
It is configured to be turned off.

Reference numeral 14 denotes a microcomputer on the indoor side. This microcomputer 14 is connected to the power supply 2 via a transformer 15 and a diode bridge I6. A DC voltage is generated by the diode bridge 16, and this DC voltage is applied to the microcomputer 14. are doing. Reference numeral 17 denotes a remote controller placed indoors, and the remote controller 17 is connected to the microcomputer 14 so that information such as the air conditioning mode and set temperature is input to the microcomputer 14. 18 is a temperature sensor such as a thermistor, which inputs room temperature information to the microcomputer 14.

Next, regarding the outdoor control circuit 1o, 3 is the above converter, which constitutes a diode bridge. The inverter circuit section 4 has six power transistors, and controls the operation of the compressor 1 connected to the inverter circuit 4 by switching these transistors. 19 is a microcomputer on the outdoor side, and is connected to the power line 1 via a transformer 20 and a diode bridge 21.
1° Power is supplied from I2. This microcomputer 19
are the bases Bu, By+BW+BX+BY+BZ of the transistors of the inverter circuit 4 in the outdoor unit 10.
A signal is outputted via the driver 22 to the four-phase coil φ1 of the expansion valve 8. φ2. Signals are output to φ3° and φ4 via the driver 23.

Now, in such a heat pump cycle, the operation of the compressor 1 is controlled according to the air conditioning load by controlling the power supply frequency by the inverter circuit 4, and
The opening degree of the expansion valve 8 is appropriately controlled according to the amount of refrigerant circulation,
As shown in FIG. 5, the refrigerant flow rate is proportionally controlled according to the valve opening degree.

The structure of this expansion valve 8 will be explained. In FIG. 6, 24 is a case, and a refrigerant discharge port 25 is provided on the lower surface of the case, and the periphery of the discharge port 25 is formed as a valve seat. Reference numeral 26 denotes a needle for controlling the amount of refrigerant discharged from the discharge port 25, and is formed to be moved up and down by a motor shaft 26 supported by the case 24, and the distance from the periphery serving as the valve seat is determined by the needle 26. The refrigerant flow rate is adjusted by Δt.

27 is a step motor for fully rotating this motor shaft 26, and this motor 27 is connected to the microcomputer 1 mentioned above.
Rotation is controlled by commands from 9. A timing chart of signals applied to the four phases of the step motor 27 is shown in FIG.

Reference numeral 28 denotes a stopper pin provided on the motor shaft 26. When the motor shaft 26 rotates to a predetermined position and descends, it comes into contact with a stopper 29 provided on the top surface of the case 24 to prevent the motor shaft 26 from rotating any further. Become ill. Incidentally, when the stopper pin 27 is in contact with the stopper 2g, Δ1 is not 0 and there is a slight gap, so that a small amount of refrigerant can flow. This takes into account variations in the dimensions of the mechanism.

Now, such an expansion valve 8 is equipped with the ability to adjust its opening degree from fully closed to fully open in N steps (for example, 240 steps), but when restarting operation after stopping the operation, the opening of the valve 8 itself is adjusted. Since the opening degree is unknown, initialize the valve opening degree. In other words,
As shown in FIG. 8, after the valve 8, which is at a predetermined opening degree, is brought to -H fully closed a, the operating opening degree is adjusted based on this fully closed state.

On the other hand, when the operation is stopped, it is necessary to balance the high and low pressures in the cycle in order to prevent the compressor from being overloaded when the operation is resumed. For this reason, I opened the expansion valve 8 for a few minutes and then turned off the power to the outdoor unit.

In this case, if the expansion valve 8 is opened too quickly, the high and low pressures will become unbalanced all at once, creating a loud noise, so to avoid this, the expansion valve 8 is opened only for a few minutes.

However, when the operation is stopped, the opening is opened for a few minutes from the opening just before the end of the operation, and then when the operation is started, it is always fully closed. It is outputted to the step motor 27 to ensure that it is in a fully closed state.

However, in order to prevent the needle 26 from getting stuck in the discharge port 25 and becoming unable to drive, the stopper pin 27. Since the stopper 28 is provided, if the driver is driven in the closing direction by (N+α) steps to fully open from a state that is not fully open (for example, assuming a N1 (N>Nl) step state), the stopper 28 will stop when the drive reaches Nl steps. The pin 27 comes into contact with the stopper 28, and the remaining (N+
α)-N+ minutes result in a blank firing state. In other words, stopper 2
Since the motor 27 continues to rotate even if the rotation is stopped at 8, the stopper pin 27 rotates slightly in reverse due to the reaction of the stopper pin 27 contacting the stopper 28, and then the motor 27 repeatedly contacts the stopper 28 and reverses again. Stopper pin 27,
Since the stoppers 28 are all made of metal, they produce a clicking sound due to the above-mentioned blank firing, which is unpleasant to the user's ears and also has a negative effect on the expansion valve itself.

<Means for solving the conventional problems> When the operation is stopped, the expansion valve is fully opened.

Once fully opened, the initial setting is performed by fully opening, so even if a fully closed command is issued by adding an extra α to N during opening adjustment, the blank firing will only be for the extra α, and this α will be Since the step width is usually very small, there are almost no blank shots.

<Example> Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing the opening degree of the expansion valve over time. FIG. 2 is a flowchart of the same example.

A control method according to an embodiment of the present invention will be explained based on FIGS. 1 and 2.

First, it is determined whether the operation is ON or OFF. When the operation is turned on by operating the operation switch, etc., the microcomputer 14 on the indoor side is completely passed through and the microcomputer 19 on the outdoor side is opened by the opening width 2.
A closing command for 250 steps, which is 40 steps plus an extra IO step, is output. The expansion valve opening degree is initialized by this fully opening, and the initial setting (c) of the expansion valve is performed based on this fully closed state. After the initial settings are made, the expansion valve opening control is turned off depending on the air conditioning status.
◇ When the operation is turned off by operating the operation switch, etc., a command to open the expansion valve 8 by 50 steps is first output from the indoor/outside microcomputer 19 to the step motor 27, and this command causes the expansion valve 8 to open by 50 steps. The step motor 27 is the needle 2
6 to open the flow path slightly. This state of opening for 50 steps is continued for 30 seconds, during which time the high and low pressures in the cycle are balanced to some extent.

After 30 seconds have elapsed, a drive command is output to the step motor 27 until it is fully open. After performing this full opening operation, the power to the outdoor unit is turned off.

In this OFF state, ON and OFF of the operation are monitored. When the operation is turned on here, the expansion valve 8 is fully closed by performing the closing drive for 250 steps, which is 240 steps during the opening and 10 steps over the opening, as described above. After the expansion valve 8 is fully opened, initial settings are made again and the opening degree of the expansion valve 8 is controlled.

Therefore, even if -H250 steps of fully-closed operation are performed at the start of operation, the expansion valve is once fully opened before the start of operation, so the expansion valve blank operation is only for an extra 10 steps, which is different from the conventional one. In comparison, there is almost no blank firing.

Further, when the operation is stopped, the valve is first opened for 50 steps and then fully opened, so that the high and low pressures are balanced to some extent when the 50 steps are opened, and no noise is generated due to the balance between high and low pressures during the fully opened operation.

Effects> As described above, according to the present invention, it is possible to suppress dry firing due to the fully closed operation at the start of operation.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the valve opening degree of an embodiment of the present invention, Fig. 2 is a flowchart of the same example, Fig. 3 is a general heat pump cycle diagram, Fig. 4 is an electric circuit diagram used in an air conditioner, # Figure f5 is a t% relationship between valve opening and flow rate, Figure 6 is a cross-sectional view of the expansion valve, Figure 7 is an input timing chart for each phase of the expansion valve, and Figure 8 is the valve opening of the conventional control method. Explanatory diagram. 8: Expansion valve, 27: Step motor.

Claims (1)

[Scope of Claims] 1. An expansion valve in an air conditioner whose opening is controlled to a desired opening after being fully closed at the start of operation, and in which the opening of the expansion valve is controlled to be fully open when the operation is stopped. Control method.