JPS62129640A - Air conditioner - Google Patents

Abstract

PURPOSE:To make it possible to shorten the time to reach a most suitable overheating with a larger initially set opening if the temperature of sucked air in an evaporator is high and a smaller initially set opening if it is low by providing a control circuit which changes an initially set opening of a flow rate control valve according to the temperature of the sucked air in an evaporator. CONSTITUTION:Outputs from a temperature sensor C which are digitized by an A/D converter 7 are led to arithmetic means 12, where the temperature difference T between the temperature T1 of the sucked air in an evaporator 4 and a set temperature T0 is calculated, and at the same time the initial valve opening for flow rate control valve 3 corresponding to this temperature difference T is calculated. And the result of the calculation is outputted from an output converter 11 to a valve 3 through set signal generating means 13 to set an initial opening of the valve 3. After this outputs from temperature sensors A and B which are digitized by an A/D converter9 are led to the arithmetic means 12 to calculate the difference SH of temperatures of the inlet and outlet in an evaporator 4 and at the same time the difference between the temperature difference SH and the set temperature difference SHO is calculated. The result of this calculation is outputted to judgement means 13 and an air conditioner is controlled so as to bring the temperature different SH closer to the set value SHO.

Description

[Detailed description of the invention] Technical fields> The present invention relates to an air conditioner.

<Prior Art> The heat medium compression cycle of a conventional air conditioner has a configuration as shown in FIG. That is, in FIG. 7,
1 is a compressor, 2 is a condenser connected to the discharge side of this compressor 1, 3 is a flow rate control valve (expansion valve) connected to the discharge side of this condenser, and 4 is the discharge side of this flow rate control valve. evaporators connected to the evaporators, which form a sequentially connected circulation circuit. 6 is a control circuit, and this control circuit 6
detects the degree of superheating in the evaporator 4 from the heat medium temperature on the inlet side a and the heat medium temperature on the outlet side of the evaporator 4, and adjusts the flow rate so that this degree of superheat becomes a set constant value. The opening degree of the control valve 3 is adjusted.

By the way, in such a conventional heat medium compression cycle, the initial valve opening setting of the flow rate control valve 3 has conventionally been constant regardless of the intake air temperature on the evaporator side.

Therefore, when the suction air temperature on the evaporator side is low, only a small amount of heat medium flows into the evaporator 4, so the flow rate control valve needs to be throttled considerably, and it takes until the optimum valve opening is reached. It takes time. During this time, the flow rate control valve becomes under-throttled.

Furthermore, when the temperature of the suction air on the evaporator side is high, a large amount of heat medium is required in the evaporator 4, and the flow control valve performs a steep opening operation until the optimum valve opening is reached. . During this time, the flow control valve is being throttled too much. For this reason, if the initial valve opening setting is constant regardless of the temperature of the intake air on the evaporator side, it takes time for the heat medium compression cycle to stabilize.

<Purpose> The present invention detects the intake air temperature of the evaporator at the start of operation, increases the initial setting opening of the flow control valve if the temperature is high, and decreases the opening if the temperature is low. The purpose is to shorten the time it takes for the compression cycle to stabilize.

<Examples> Examples of the present invention will be described below with reference to the drawings. Note that parts that are the same as the conventional ones are given the same reference numerals.

In Fig. 1, 1 is a compressor, 2 is a condenser, 3 is a flow control valve (expansion valve) whose opening degree can be adjusted, and 4 is an evaporator, which are connected in sequence to perform a heat medium compression cycle. It consists of

Reference numeral 6 denotes a control circuit that electrically controls the opening degree of the flow rate control valve 3, and this control circuit 6 controls the opening degree of the control valve 3 based on the temperature detected by the intake air temperature sensor C of the evaporator 4. The opening degree of the flow control valve 3 is controlled based on the degree of superheating based on the temperature difference between the inlet and outlet heat medium temperatures detected by temperature detectors A and B provided on the inlet and outlet sides of the evaporator 4. It controls the

The evaporator 4 functions as an indoor heat exchanger during the cooling cycle and as an outdoor heat exchanger during the heating cycle. In an air conditioner capable of cooling/heating operation, temperature detectors A, B, and C are actually attached to both an indoor heat exchanger and an outdoor heat exchanger that can serve as evaporators.

This control circuit 6 will be explained in more detail using FIG. 2. In FIG. 2, the control circuit 6 includes an A/D converter 7 that converts the detection output of the intake air temperature detector C of the evaporator 4 into a digital quantity, and an A/D converter 7 that receives the output of the A/D converter 7. , a control unit 8 that generates a signal for setting the initial opening degree of the flow rate control valve 3, and the detection outputs of temperature detectors A and H provided on the inlet side and the outlet side of the evaporator 4, respectively, are converted into digital quantities. An A/D converter 9 that converts the temperature into a 100% A/D converter 9, and a temperature difference SH (degree of superheat) between the inlet temperature and the outlet temperature is calculated based on the output from this A/D converter 9, and this SH is set to a certain target. The superheat degree S is calculated to maintain the value 5HO (set superheat degree).
A control unit 8 generates a signal for controlling the opening of the flow rate control valve 3 according to H, and a signal generated by the control unit 8 is converted and outputted in order to be transmitted to the drive unit of the flow rate control valve 3. It is composed of an output converter 11.

The control section 8 is composed of an electric circuit including, for example, a microcomputer, and has a configuration as shown in FIG. 3. In FIG. 3, 12 is a calculation means, and this calculation means 12 calculates the difference between the intake air temperature T1 of the evaporator 4, which is the detection output from the A/D converter 7, and the set temperature TQ (20°C). By calculating , the initial opening degree of the flow control valve 3 is calculated. 1
Reference numeral 3 denotes a setting signal generating means for generating a signal for setting the opening degree of the flow rate control valve 3 in accordance with the result of the above calculation. In addition, as a specific method for setting the initial valve opening degree of the flow control valve 3, the suction air temperature T1 of the evaporator 4 and the set temperature T
The temperature difference T between O and O is calculated, and if T1 >To, the initial valve opening is set to the basic opening 10T. Further, if TI<To, the initial valve opening is set to the basic opening - 1. In other words, the larger T1 is, the greater the initial valve opening degree is, and the smaller T1 is, the smaller the initial valve opening degree is proportional control (proportional setting).

Further, the calculating means 12 calculates the degree of superheating SH by calculating the difference between the inlet temperature SHI and the outlet temperature SH2 of the evaporator 4, which are the detection outputs from the A/D converter 9, and also Calculate the difference from the superheat degree SHO.

Further, 13 is a means for determining whether or not the degree of superheating SH has reached the set value SHO based on the result from the calculation means 12, and the difference between the set value SHO and the degree of superheat 5l-1 is When the superheat degree SH reaches the set value SHO, a SHO reaching signal is generated.

14 is a control signal generating means for generating a signal for controlling the opening of the flow rate control valve 3 according to the result of the determination means 13 and the setting signal generating means; Means 14 generate a control signal for bringing the degree of superheating SH closer to a set value S HO.

A specific method for bringing the degree of superheating SH closer to the set value SHO is to increase the valve lift when SH increases in response to a change in the temperature difference SH, and conversely to increase the valve lift when SH decreases. , the proportionality (P) that causes the valve lift to decrease
The opening of the flow rate control valve is controlled by combining control and integral (I) control, which calculates the deviation between the temperature difference SH and the target set value S HO, and changes the valve lift in a direction that corrects the deviation at regular intervals. (P・■ control), the temperature difference SH becomes S I
-10.

Returning to FIG. 2, the signal generated by the control unit 8 is outputted from the output converter 11 and sent to an opening adjustment means such as a drive control unit of a drive motor that adjusts the valve lift of the flow rate control valve. A signal is transmitted.

Now, regarding the operation of this control circuit 6, 70-- in FIG.
To explain with reference to the chart, first, A/D converter 7
The output of the temperature detector C digitized by
The temperature difference T between 1 and the set temperature TO is measured, and the initial valve opening degree of the flow rate control valve 3 according to this temperature difference T is calculated. Then, the result of the calculation in item 1 is the flow rate control valve 3.
The signal is outputted from the output converter 11 to the flow control valve 3 through the setting signal generating means 13 which generates a signal for setting the opening of the flow control valve 3, and the initial opening of the flow control valve 3 is set. Thereafter, the outputs of the temperature detectors A and B digitized by the A/D converter 9 are introduced into the calculation means 12, so that the temperature difference (superheat degree) SH at the entrance and exit of the evaporator 4 is calculated as
At the same time, the difference between this temperature difference SH and the set temperature difference (set superheat degree) SHO is calculated. This calculation result is output to the determination means 13, and the temperature difference 5I-1 becomes the set value S l-
Whether the temperature difference SH has reached 10=7- is determined, and if the temperature difference SH has not reached the set value SHO, the above-mentioned P-I control is performed.

Therefore, since the initial opening of the flow rate control valve 3 is set according to the suction air temperature of the evaporator 4 at the start of operation, there is almost no time loss until the optimum valve opening is reached, and the heating medium is The compression cycle becomes stable.

This will be explained with reference to FIGS. 5 and 6.

FIG. 5 shows a case where the temperature of the intake air of the evaporator 4 is high, where the solid line is the present invention and the broken line is the conventional one. Conventionally, P/I control was performed to reach the optimum superheat degree from point D, which is the initial setting opening degree. For this reason, it took E minutes to reach the optimum degree of superheating, and during that time the flow rate control valve was throttled too much. In the present invention, since point F, which is the sum of temperature difference T to point D, is the initial setting opening degree, the optimum degree of superheating can be reached immediately.

Moreover, FIG. 6 shows the sixth case when the suction temperature of the evaporator 4 is low.
As in the figure, the solid line is the conventional one, and the broken line is the conventional one.

Conventionally, P・■ control was performed from point D, which is the initial setting opening, so it took E minutes, and during that time, the flow rate control valve 3
The aperture was insufficient. In the present invention, since point F, which is obtained by subtracting the temperature difference T from point D, is the initial setting opening degree, the optimum degree of superheating can be quickly reached.

<Effects> As is clear from the explanation in section 2 below, the present invention includes a compressor that compresses and discharges a heat medium, a condenser connected to the compressor, and a flow rate control valve that connects the condenser to the compressor. In an air conditioner in which a heat medium compression cycle is configured with an evaporator connected on one side and connected to the compressor on the other side, a temperature detector is provided for detecting the temperature of the intake air of the evaporator, and the temperature detector A control circuit is provided for controlling the valve opening of the flow control valve based on an output signal of the flow control valve, and the control circuit increases the valve opening of the flow control valve at the start of operation when the intake air temperature of the evaporator is high;
The present invention relates to an air conditioner characterized by having a function of controlling the setting to be small when the temperature is low.

Therefore, according to the present invention, a control circuit is provided that changes the initial setting opening degree of the flow control valve depending on the evaporator suction air temperature. By making it as small as possible, there is an excellent effect that the time required to reach the optimum superheat degree can be shortened and the heat medium compression cycle can be stabilized quickly.

[Brief explanation of drawings]

Fig. 1 is a diagram of the heat medium compression cycle used in the embodiment of the present invention, Fig. 2 is a block diagram of the control circuit, Fig. 3 is a block diagram of the control section, Fig. 4 is the flowchart, Fig. 5, FIG. 6 is a diagram showing the relationship between the degree of superheating, the degree of valve opening, and time in the embodiment of the present invention, and FIG. 7 is a diagram of a conventional heat medium compression cycle. 1: Compressor, 2: Condenser, 3: Flow rate control valve, 4: Evaporator, 6: Control circuit, 7, 9: A/D converter, 8: Control section, 11: Output converter, 12: Calculation means, 13: determination means, 14: control signal generation means.

Claims (1)

[Claims] A heat medium is supplied from a compressor that compresses and discharges a heat medium, a condenser connected to the compressor, and an evaporator whose one side is connected to the condenser via a flow control valve and the other side is connected to the compressor. The air conditioner configured with a compression cycle is provided with a temperature detector that detects the temperature of the intake air of the evaporator, and a control circuit that controls the valve opening of the flow rate control valve based on the output signal of the temperature detector. The control circuit is characterized in that it has a function of controlling the valve opening of the flow rate control valve at the start of operation by setting it large when the intake air temperature of the evaporator is high and small when it is low. Air conditioner.