JPS5937421B2 - Refrigerant cycle refrigerant flow control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a refrigerant flow rate control device for a refrigeration cycle in an air conditioner.

Conventional Structure and Problems Conventionally, in the refrigeration cycle of an air conditioner, as shown in FIG.
The refrigerant is sucked into the compressor 1 after passing through the thermal expansion valve 3 and the evaporator 4.The refrigerant flow rate is controlled by detecting the refrigerant temperature in the evaporator 4 at the same time as the start of operation. The opening degree of the thermal mold engraving expansion valve 3 is controlled by an electronic control device 7 that connects a first temperature sensor (thermistor) 5 that detects the outlet temperature of the evaporator 4 and a second temperature sensor (thermistor) 6 that detects the outlet temperature of the evaporator 4. control and maintain appropriate cooling or heating conditions according to the load.

As shown in FIG. 2, the expansion valve 3 is equipped with a bimetal 3B that is displaced according to the amount of heat generated by the electric heater 3H, and the valve body 3C and the valve seat 3D are opened depending on the amount of current applied to the electric heater 3H. It was a configuration in which the temperature was controlled.

In this case, the control circuit is as shown in Figure 3, the power supply +VoO
and 1st. First thermistor 5 as second temperature sensor
a, a second thermistor 6a forming a series circuit with the thermistors 5a and 6a, an amplifier 8 that receives the voltage vT obtained by dividing the power supply voltage by the thermistors 5a and 6a, and a buffer 9 that amplifies the output of the amplifier 8. ing.

In this circuit, the difference between the evaporator outlet temperature Ts and the temperature TR given by the evaporator center temperature is given by the voltage vT, and if the voltage vT is positive, TR>Ts, and if it is negative, T
R<'rs.

Therefore, if TR>Ts, then vT>o, which is inverted and amplified by the amplifier 8 and buffer 9, and the electric heater 3H
The applied voltage vH becomes smaller, the opening degree of the expansion valve 3 becomes smaller, the refrigerant flow rate decreases, and the temperature Ts increases.

If 'rR<'rs, vT<o, the opening degree of the expansion valve 3 becomes a dog, the refrigerant flow rate increases, and the temperature 'rs decreases.

By repeating the above operations, the refrigerant temperature T at the outlet of the evaporator 4 is
By keeping s constant, the degree of superheating is kept constant.

This control circuit is constructed as shown in Fig. 3, and the temperature deviation Δ
For T-=(Ts-TR,), it has the characteristics as shown in FIG.

That is, the voltage vH applied to the electric heater 3H is VH-1 to 1・■T10vcc 2Kt(K2”ΔT)+Vac However,: Gain of amplifier 8 2:ΔT=VT conversion constant.

Here, is fixed, K1=RB/RA (A: resistance value of resistor 8A, B: resistance value of resistor 8
This is the resistance value of B.

Also, the constant is 1. 2 is selected so that the refrigeration cycle operates stably without bunching over the entire load range Q.

However, in this control device, since the refrigeration cycle is very unstable when the compressor starts operating, the temperature deviation ΔT fluctuates greatly, and if this is controlled as it is, it will cause malfunction.

Another problem is that it takes a considerable amount of time until the refrigeration cycle becomes stable, since the refrigerant flow rate is determined depending on the temperature deviation.

OBJECTS OF THE INVENTION The present invention is intended to eliminate the above-mentioned conventional drawbacks, and one of its objects is to stabilize the refrigerant flow rate control operation.

Structure of the Invention To achieve this object, the present invention detects the temperature at the inlet or intermediate part of the evaporator with a first temperature detection means, as shown in FIG. The temperature is detected by the second temperature detection means, the outputs of the first and second temperature detection means are compared by the comparison means Q, the comparison result is inputted to the inversion detection means, and the signal of this inversion detection means is Then, the output of the timing means for measuring the time after the start of compressor operation is input to the transition means, and based on the comparison result, the output means controls the amount of electricity to be applied to the electric heater of the thermoelectric expansion valve in stages. It is something to do.

This allows stabilization of the refrigeration cycle after it starts operating in a short period of time.

DESCRIPTION OF THE EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 6 to 10 of the accompanying drawings.

In FIG. 6Q, the control circuit includes an AC power supply 10, a body switch 11, a transformer 12, a rectifier circuit 13, and a capacitor 1.
The power supply circuit is constructed from 4G, and a microcomputer (hereinafter referred to as LSI) 15 controls the entire air conditioner, a timer control circuit 16 controls the internal timer circuit of the LS 115, an operation input switch 17, and an indoor fan motor. Output circuit 18, compressor output circuit 19, evaporator (
(not shown), a second thermistor 6a that detects the evaporator outlet temperature, and a comparison circuit that detects the difference between the evaporator outlet temperature Ts and the evaporator center temperature TR. 20. Output circuit 21 that controls the voltage supply to the heater 3H provided inside the expansion valve shown in FIG.
and an electric heater 3H for the expansion valve.

Here, to explain the relationship between the block circuit shown in FIG. 5 and the control circuit shown in FIG.
The thermistor 5a and the second thermistor 6a correspond to the first temperature detection means and second temperature detection means shown in FIG. 5, and the comparison circuit 20 shown in FIG. 6 corresponds to the comparison means shown in FIG. Furthermore, the LS 115 and the timer control circuit 16 in FIG. 6 correspond to the time measurement means, transition means, and storage means in FIG. 5, and the output circuit 21 in FIG. 6 corresponds to the D/A conversion means in FIG. ,
The output means corresponds to an electric heater.

Next, the structure and operation of the control circuit having the above structure will be explained with reference to FIGS. 7 to 10.

If the evaporator outlet temperature Ts is higher than the temperature TR given by the evaporator center temperature, the output from the comparator circuit 20 becomes H, which is input to the LS 115.

Further, if the evaporator outlet temperature Ts is lower than the temperature TR given by the evaporator center temperature, the output from the comparison circuit 20 is L.
Then, it is input to LSI 15.

The LS 115 receives the output from the external timer 16 and has an internal timer function that counts a certain period of time.

Depending on the input status from this timer or comparison circuit 20,
The output state of the output circuit 21 is changed to control the voltage vH supplied to the electric heater 3H of the expansion valve 3.

Furthermore, this LS115 has a storage means for storing which operating mode it is operating in, out of the predetermined first mode and second mode, and has a storage means for storing the electric heater 3H.
The supply voltage vH to is controlled.

The contents of control from this LS 115 are shown in FIGS. 7 and 8.

That is, in the same figure, when the compressor is operated, the output port 211 or H becomes the output port 211 or H for a certain period of time T1 from the start of the compressor operation as the first output mode, and the constant voltage VHt is supplied to the electric heater 3H of the expansion valve, and the refrigeration Control is not changed when the cycle is unstable.

Also, after a certain time T1 has passed, the second output mode is set, and as long as the input from the comparator circuit 20 is not inverted, the output mode is set for a predetermined time T2.
lapses, a constant voltage deviation ΔV is added to the supply voltage vH to control the opening degree of the expansion valve 3 in the positive direction.

Therefore, the output port 211. '212 respectively become H, and the voltage VH2 is supplied to the expansion valve heater 3H.

Furthermore, when time T2 elapses, output capo-1-211, 21
3 becomes H, and the voltage VH3 is applied to the expansion valve heater 3H.
is supplied.

Similarly, the output ports 1-21L214 are set to H, and the voltage vH4 is supplied to the expansion valve heater 3H, and the refrigerant amount is minimized (or increased) regardless of the temperature deviation Δt=(Ts TR,) to start the refrigeration cycle. stabilize quickly.

Which port is set to H for this output supply is defined, for example, as shown in Figure 9, and the resistance from each port is R2□1 J R212) R213JR214
J R2155R216 values should be determined appropriately.

If this situation is expressed using the relational characteristic of output voltage V-flow rate Q, it will become as shown in FIG.

Effects of the Invention As is clear from the above embodiments, the refrigerant flow rate control device for a refrigeration cycle according to the present invention includes a first temperature sensor provided at the evaporator inlet or intermediate portion, and a first temperature sensor provided at the evaporator outlet. The valve opening of the thermoelectric expansion valve is controlled by the temperature data from the second temperature sensor, a timer that outputs a time signal, and the stored output mode contents of the valve controller, so if the refrigeration cycle is not stable, It has excellent features such as preventing malfunctions, reducing the amount of time it takes to follow fluctuations in the refrigeration cycle by reducing the refrigerant flow rate as low as possible (or high flow rate), and enabling stable refrigerant flow control. You can get some effect.

[Brief explanation of drawings]

Fig. 1 is a diagram of a refrigeration cycle equipped with a refrigerant flow control device showing the basic control of the present invention, Fig. 2 is an internal sectional view of a thermoelectric expansion valve in the refrigerant flow control device, and Fig. 3 is a thermal chamber type expansion valve. A schematic control circuit diagram for controlling the opening and closing of the valve, FIG. 4 is a characteristic diagram showing the control relationship between the input voltage vT of the amplifier and the voltage vH applied to the electric heater in the control circuit of FIG. 3, and FIG. A block diagram expressing the refrigerant flow rate control device of the present invention using function realizing means, FIG. 6 is a control circuit diagram embodying the refrigerant flow rate control device, FIG. 7 is a flowchart of the control device, and FIGS. 8a and b 9 is a characteristic diagram showing the energization state to the thermoelectric expansion valve when the refrigeration cycle is stabilized by the same control device, FIG. 9 is a voltage characteristic diagram of the output port of the LSI in the control circuit Q shown in FIG. 6, and FIG. FIG. 10 is a characteristic diagram showing the relationship between the output voltage V and the flow rate Q, showing the change in the flow rate when the refrigeration cycle is stabilized in the control device O. 3...Thermoelectric expansion valve, 3H...Electric heater, 5...First temperature sensor, 5a...
...First thermistor, 6...Second temperature sensor, 6a...Second thermistor, 7...
・Electronic control unit, 15...LSI, 20...
... Comparison circuit, 21 ... Output circuit.

Claims (1)

[Claims] 1 A refrigeration cycle is constructed by connecting a compressor, a condenser, a pressure reducing device, and an evaporator in a ring, and the pressure reducing device is composed of an electric heater, a bimetal whose degree of curvature changes depending on the heating degree of the electric heater, and a bimetallic A thermal mold engraving expansion valve consisting of a valve body whose opening degree is controlled depending on the degree of curvature, and further provided with an energization amount control device for controlling the amount of energization of the electric heater, and this energization amount control device is connected to the electric heater. an output means for controlling the output voltage stepwise in the direction of increasing or decreasing through D/A conversion; and an output means provided at the inlet or intermediate portion of the evaporator and converting the refrigerant temperature into an electrical signal. Comparing the magnitude of the electric signals from the first temperature detection means, the second temperature detection means provided at the outlet of the evaporator and converting the refrigerant temperature into an electric signal, and the first and second temperature detection means. a first output mode for keeping the output voltage of the output means constant;
storage means storing a second output mode for controlling the output voltage of the output means stepwise in the direction of increasing or decreasing; and storage means storing the operating time of the first output mode and the second output mode Q. a clock means for measuring stepwise variable control time of the output voltage in the output voltage; a reversal detecting means for detecting reversal of the output of the comparing means; A refrigerant flow rate control device for a refrigeration cycle, comprising a transition means for shifting an output mode from a first output mode to a second output mode.