JPH0473052B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a capacity control device for an air conditioner having a control function for varying air conditioning capacity in response to load fluctuations.

Conventional technology Conventionally, as shown in Japanese Utility Model Publication No. 53-10588, an automatic expansion valve is used as a throttling device in a refrigeration cycle to control the refrigerant temperature, etc. as shown in Japanese Utility Model Publication No. 53-10588. The opening degree of the automatic expansion valve was controlled by the fluctuation, and the capacity was controlled.

Furthermore, in recent years, for example, as shown in Japanese Patent Publication No. 59-34935, the rotational speed of the compressor is varied using an inverter device, and capacity control is also performed in accordance with load fluctuations.

Problems to be Solved by the Invention However, in the former case, there is a problem that the compression function is constant and the load fluctuation range that can be handled is small, and the control content is the same for both heavy loads and light loads. Because it is driven,
Particularly when the load is light, the compressor operates and stops frequently, and as a result, the room temperature fluctuates greatly due to the time required for pressure balance due to the stoppage of the compressor, causing a problem in which comfort is impaired.

In the latter case, although the problem of the former mentioned above is solved, there is a limit to the lowest operating frequency due to the compressor's lubricating oil supply capacity, and as with the former, the compressor The room temperature must be controlled by starting and stopping the system, and there is a problem in that the room temperature fluctuates widely.

The present invention aims to improve comfort in view of the above-mentioned conventional problems.

Means for Solving the Problems In order to solve the above problems, the present invention provides a control device that controls the operating frequency of a compressor and a refrigerant flow rate using an electric valve device, a load detection means for detecting an air conditioning load, and a load detection means for detecting an air conditioning load. A load determining means for determining an increase or decrease in air conditioning load based on a signal from the detecting means, and an ability to increase or decrease the operating frequency of the compressor and the refrigerant flow rate by the electric valve device in accordance with the increase/decrease signal of the load determining means. The capacity control means includes a frequency variable means for varying the operating frequency according to an increase/decrease signal from the load determining means, and a lowest frequency determining means for determining that the operating frequency is the lowest. , a valve driving means for driving the electric valve device to open and close; and a signal from the load determining means to be outputted to a frequency variable means; It is composed of an output determining means for outputting a signal to the valve driving means.

Effect With this configuration, especially when the compressor is operated at the lowest frequency corresponding to the load size at that time, the electric valve device can control the capacity more precisely, expanding the load response range. can.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

First, the refrigeration cycle structure will be explained with reference to FIGS. 2 and 3.

In Fig. 2, 1 is a compressor whose capacity is variable by an inverter, 2 is a four-way valve, 3 is an indoor heat exchanger, 4 is an electric expansion valve, and 5 is an outdoor heat exchanger, which are connected in a ring. This constitutes a refrigeration cycle.

The electric expansion valve 4 is equipped with a stepping motor (hereinafter referred to as a motor) that rotates in small increments by intermittent pulse output, as shown in FIG. 3, for example.
4a, and the valve seat 4b is rotated by the rotation of the motor 4a.
It is composed of a needle 4c that adjusts the opening degree of the needle 4c.

Further, the compressor 1 and the electric expansion valve 4 are operated by a control device 7 that determines the load based on a signal from a temperature sensor 6 that detects the pipe temperature of the indoor heat exchanger 3, etc.
Its operation is controlled by

Next, the configuration of the control device 7 will be explained.

The control device 7 includes, as shown in FIG. 1, a load determining means for determining an increase or decrease in the air conditioning load based on a signal from the load detecting means (temperature sensor 6 in FIG. 2);
Depending on the signal from this load determining means, a frequency variable means for varying the operating frequency of the compressor or a valve driving device 7 (as shown in FIG. 3) that controls an electric valve device (electrically operated expansion valve 4 in FIG. 2) is used. Output determining means for determining which of the motors 4a) is to be controlled and outputting to the selected side; and minimum output determining means for determining whether the operating frequency of the compressor is the lowest and outputting to the output determining means. It is comprised of a frequency determining means and a valve opening degree determining means for determining whether the valve opening degree of the expansion valve device is the minimum.

Furthermore, the configuration of the control circuit will be explained with reference to FIG. Here, the same parts as in FIGS. 2 and 3 are given the same reference numerals, and the explanation will be omitted.

In the figure, a comparator 11 compares the detection signal from the temperature sensor 6 with a set value set in the microcomputer 12, and the set value can be arbitrarily varied as is well known.
The comparator 11 corresponds to the load determining means in FIG. 13 is an inverter which creates the operating frequency of the compressor 1, and together with the microcomputer 12 constitutes the frequency variable means shown in FIG. 14
1 is a buffer that generates a pulse output for driving the motor 4a, which together with the microcomputer 12 constitutes the valve driving means shown in FIG. 15 is a variable resistor for setting the room temperature, and 16 is a scan resistance group for creating a set value for the load determination. Reference numeral 17 denotes an operation switch for operating the microcomputer 12 for finely controlled performance. In addition to the above, the microcomputer 12 is also equipped with minimum frequency determining means and valve opening degree determining means shown in FIG.

Next, we will discuss the control operation with the above configuration in the fifth section.
This will be explained with figures. Here, for convenience of explanation,
Only the point where the operation switch 17 is turned on and fine-grained capacity control is performed will be described.

When the operation switch is turned on and the compressor 1 is driven with the operating switch 17 turned on, the refrigerant flows as shown by the solid line arrow during cooling and as shown by the broken line arrow during heating. Hereinafter, for convenience of explanation, the explanation will be made in terms of cooling.

At the initial setting stage shown in FIG. 5, the valve opening degree of the electric expansion valve 4 is set, for example, to the minimum, and the compressor 1 is operated at a predetermined frequency.

Then, the temperature sensor 6 detects the pipe temperature, and the load determining means determines the load state based on the increase in the pipe temperature. When the air conditioning load is large, that is, when the capacity is insufficient, the pipe temperature rises, and the valve opening degree of the electric expansion valve 5 is increased by one step. If the valve opening is not at its maximum, the system waits for a predetermined period of time for temperature detection again, and repeats this operation thereafter.

In the above operating state, when the valve opening determination means detects that the valve opening has reached the maximum, the frequency variable means including the inverter 13 increases the operating frequency of the compressor 1 by one step.

When the capacity is insufficient, the capacity is finely controlled by the above-mentioned valve opening degree control and frequency control.

On the other hand, if the capacity is too large, the pipe temperature will decrease, so the load determination means determines this, and the frequency variable means lowers the operating frequency of the compressor 1 to lower the capacity.

Then, unless the valve opening degree of the electric expansion valve 4 is the minimum, the above-mentioned operation is repeated to perform capacity control.

When the operating frequency of the compressor 1 reaches the minimum, the opening degree of the electric expansion valve 4 is adjusted stepwise in the direction of closing, and if the pipe temperature further decreases when the operating frequency reaches the minimum, the capacity will be excessive. It is determined that the operation of the compressor 1 is stopped.

With the above control, when the user turns on the operating switch 17 to finely control the capacity, such as when sleeping, the electric expansion valve 4 finely varies the capacity, so the compressor 1 is simply Compared to rough control that increases the operating frequency in steps, power consumption is lower. In addition, especially when the air conditioning load is small and the compressor 1 has excess capacity even if it is operated at the lowest operating frequency, the electric expansion valve 4 provides more detailed control, so you can simply start or stop the compressor. Therefore, compared to control that adjusts the room temperature, temperature changes are smaller and comfort is improved.

Although the cooling operation has been described in this embodiment, the heating operation can also be carried out in the same way by reversing the opening and closing direction of the electric expansion valve 4, and is beyond the scope of the present invention. It's not a thing.

Effects of the Invention As described above, the present invention enables detailed capacity control as required, improving comfort. In particular, capacity control is achieved by the electric expansion valve even when the compressor operating frequency is at its lowest. As a result, the range in which load fluctuations can be handled is expanded, and compared to temperature control using intermittent operation of the compressor, temperature changes are kept small, further improving comfort. Further, such control is highly reliable because capacity control can be performed without causing a shortage of lubricating oil in the compressor.

[Brief explanation of drawings]

Fig. 1 is a block diagram expressing the capacity control device of the present invention as a function realizing means, Fig. 2 is a block diagram including the refrigeration cycle of an air conditioner equipped with the capacity control device, and Fig. 3 is a block diagram of the refrigeration cycle of the air conditioner equipped with the capacity control device. FIG. 4 is a sectional view of the electrically operated expansion valve, FIG. 4 is a schematic electrical circuit diagram of the same-capacity control device, and FIG. 5 is a flowchart showing the operation details of the same-capacity control device. 1...Compressor, 3...Indoor heat exchanger, 4...Electric expansion valve, 5...Outdoor heat exchanger, 6...Temperature sensor, 7...Control device, 11...Comparator,
12...microcomputer, 13...inverter, 14...batshua.

Claims (1)

[Claims] 1 variable frequency compressor, indoor heat exchanger,
An expansion valve device and an outdoor heat exchanger are connected in a ring to form a refrigeration cycle, the expansion valve device is an electric valve device that controls the refrigerant flow rate by intermittent signals, and the compression A control device is provided to control the operating frequency of the machine and the refrigerant flow rate by the electric valve device, and this control device is controlled by a load detection means for detecting the air conditioning load and a signal from the load detection means to increase or decrease the air conditioning load. and a capacity control means for increasing or decreasing the operating frequency of the compressor and the refrigerant flow rate by the electric valve device in accordance with the increase/decrease signal of the load determining means,
Further, the capacity control means includes a frequency variable means for varying the operating frequency according to an increase/decrease signal from the load determining means, a lowest frequency determining means for determining that the operating frequency is the lowest, and the electric valve device. A valve driving means for driving the opening and closing, a signal from the load determining means is outputted to the frequency variable means, and a signal from the load determining means is sent to the valve driving means according to the lowest operating frequency signal of the lowest frequency determining means. A capacity control device for an air conditioner, comprising an output determination means.