JPS5937420B2 - Refrigerant cycle refrigerant flow control device - Google Patents

Description

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

Conventional Structure and Problems Conventionally, in the refrigeration cycle of an air conditioner, refrigerant discharged from a compressor 1 sequentially passes through a condenser 2, a thermoelectric expansion valve 3, and an evaporator 4, as shown in FIG. The refrigerant flow rate is controlled by a first temperature sensor 5 that detects the refrigerant temperature of the evaporator 4 and a refrigerant of the evaporator 4 at the same time as the start of operation. The opening degree of the thermoelectric expansion valve 3 was controlled by an electronic control device 7 connected to a second temperature sensor 6 that detects the outlet temperature, and an appropriate cooling or heating state was maintained depending on the load.

The expansion valve 3 is connected to an electric heater 3H as shown in FIG.
The opening of the valve body 3C and the valve seat 3D is controlled by the amount of electricity supplied to the electric heater 3H.

In this case, the circuit is connected to the power supply +V as shown in Figure 3.
cc, a first thermistor 5a and a second thermistor 6a as first and second temperature sensors, both thermistors 5a
, 6a, and a buffer 9 that amplifies the output of the amplifier 8.

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, 'rR>'rs, and if it is negative, TR It is Ts.

Therefore, if T□>Ts, vT>o, which is inverted and amplified by the amplifier 8 and buffer 9,
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 TR>Ts, vT<o, the valve opening 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 a characteristic as shown in FIG.

That is, the voltage vH applied to the electric heater 3H is VH2 K1 “VT+VCC 2 Kt(K2”ΔT) +Vcc However, K1: Gain of amplifier 8 2:ΔT=VT conversion constant.

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

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

However, in this control device, the thermoelectric expansion valve 3 generally has voltage-flow characteristics as shown in FIG. 5 (normally open type that closes when energized) and FIG. 6 (normally closed type that opens when energized). With a simple proportional-integral type control device as shown in FIG. 3, even if this type of expansion valve 3 is controlled, it is difficult to eliminate the hysteresis characteristic seen in the voltage-flow characteristic. If controlled by a method, for example, T
Even if the heater voltage vH is increased to increase the valve opening of the expansion valve 3 at R〈Ts, the flow rate does not change, and after a considerable period of time, the flow rate increases and the device changes in the direction of decreasing the degree of superheating. is activated.

In other words, such conventional control is performed when the outlet of the evaporator 4 is too wet or the degree of superheat is too high, which slows down the recovery operation of the device and prevents the refrigeration cycle from functioning properly. The problem is that it takes a long time to return.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned conventional drawbacks, and aims to shorten the time it takes for the refrigeration cycle to stabilize.

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, the comparison results are inputted to the reversal detection means and the transition means, and the storage means stores them. The energization of the electric heater of the thermoelectric expansion valve is controlled in order from the first output mode to the second output mode, and in the first output mode and the second output mode, the output means G'
In addition to controlling the voltage applied to the electric heater in stages,
The output control deviation means makes the initial output value in the reverse direction Q larger than the value subsequently output in the same direction.

Thereby, stabilization of the refrigeration cycle after the start of operation can be achieved in a short time.

DESCRIPTION OF THE EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 8 to 12 of the accompanying drawings.

Here, a heat conductive expansion valve having the characteristics shown in FIG. 5 is used.

In FIG. 8, the control circuit includes an AC power source 10, a body switch 11, a transformer 12, a rectifier circuit 13, and a capacitor 14.
A microcomputer (hereinafter referred to as LSI) 1 constitutes the power supply circuit and controls the entire air conditioner.
5. Detects the temperature near the center of the timer control circuit 16 that controls the internal timer circuit of LS115, the operation input switch 17, the indoor fan morph output circuit 18, the compressor output circuit 19, and the evaporator (not shown). The first thermistor 5
a, a second thermistor 6a that detects the outlet temperature of the evaporator;
, a comparison circuit 20 that detects the difference between the evaporator outlet temperature Ts and the evaporator center temperature TI (,), an output circuit 21 that controls the voltage supply to the electric heater 3H provided inside the expansion valve shown in FIG. An electric heater 3H for the expansion valve is provided.

Now, to explain the relationship between the block circuit shown in FIG. 7 and the control circuit shown in FIG. 8, the first thermistor 5a and the second thermistor 6a shown in FIG. The comparison circuit 20 in FIG. 8 corresponds to the comparison means G in FIG. 7,
Furthermore, the LS 115 and the timer control circuit 16 in FIG. 8 correspond to the time measurement means, transition means, storage means, and output control deviation means in FIG. 7, and the output circuit 21 in FIG.
/A conversion means, output means, and electric heater.

Next, the configuration and operation of the control circuit with the above configuration will be explained in the ninth section.
This will be explained with reference to FIGS.

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;
It is input to LS115.

If the evaporator outlet temperature Ts is lower than the temperature TR given by the evaporator center temperature, the output from the comparator circuit 20 becomes L and is input to the LS115.

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 the timer or comparison circuit 20, the output status of the output circuit 21 is changed to control the voltage vH supplied to the electric heater 3H of the expansion valve 3.

Moreover, this LS115 has a predetermined first,
It has a storage means for storing which operation mode it is operating in among the second modes, and the supply voltage v to the electric heater 3H.
It controls H.

The control contents from this LSI 15 are shown in Figure 9 and Figure 1.
0, and its mode will be explained.

That is, when the compressor is operated, the output port 2 is in the first output mode for a certain period of time T1 from the start of the compressor operation.
11 becomes H, and a constant voltage VHI is supplied to the electric heater 3H of the expansion valve.

If the output from the comparator circuit 20 is not inverted after the predetermined time T1 has elapsed, the timer outputs T1.
After time elapses, the voltage changes from H1 to vH2Q.

Further, when the output from the comparator circuit 20 is inverted and the first output mode shifts to the second output mode, the voltage supplied to the expansion valve 3 changes from Vk12 to VH3.

Also, which output port is set to H for this output supply is defined, for example, as shown in Fig. 11, and the resistance value from each port is R211t R212J R21
3J R214? R215J R216 value is O
All you have to do is decide.

At this time, the voltage deviation Δv1-1 (VH2VHI)l controlled by the timer time T1G is the voltage deviation ΔV2 = l (controlled by the input from the comparator circuit 20).
Port 211 so that it is smaller than VH2-VH3]
~216 is selected and the LS115 controls the output.

Hereinafter, the amount of current applied to the heater 3H of the expansion valve 3 is controlled by this output mode, and when ΔT2 (evaporator amount temperature Ts - evaporator center temperature Tn) is reversed, the valve opening is the same as before the reversal. The voltage deviation in the direction of the opening in the opposite direction is ΔV2, and when the timer outputs the voltage deviation in the same direction as the previous valve opening, ΔV1 (this control is performed to eliminate the hysteresis of the valve itself (the deviation value is ΔV2>ΔV1).

By repeating this, the time required for the refrigeration cycle to stabilize can be shortened.

If this situation is expressed using voltage-flow characteristics, it will be as shown in FIG. 12.

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 Q. The valve opening of the expansion valve is controlled by the temperature data from the second temperature sensor, a timer that outputs a time signal, and a memory that stores the output mode of the valve controller. By changing the deviation between G during reversal and non-reversal, excellent effects such as eliminating the hysteresis of the valve itself, shortening the time to follow fluctuations in the refrigeration cycle, and enabling stable refrigerant flow control are achieved. It will be done.

[Brief explanation of drawings]

Fig. 1 is a diagram of a refrigeration cycle equipped with a refrigerant flow rate control device showing the basic control of the present invention, Fig. 2 is an internal sectional view of a thermal mold engraving expansion valve in the refrigerant flow rate control device, and Fig. 3 is a diagram of a refrigeration cycle equipped with a refrigerant flow rate control device showing the basic control of the present invention. A schematic control circuit diagram for controlling the opening and closing of the expansion valve, FIG.
FIG. 5 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 shown in FIG.
Fig. 6 is a voltage-flow characteristic diagram of the thermal die engraving expansion valve in the normally open type and normally open type, respectively, Fig. 7 is a block diagram expressing the refrigerant flow rate control device of the present invention as a function realizing means, and Fig. 8 The figure is a control circuit diagram embodying a refrigerant flow rate control device in one embodiment of the present invention, FIG. 9 is a flowchart of the same control device, and FIG.
Figures 0 a and b are characteristic diagrams showing the energization state to the thermoelectric expansion valve when the refrigeration cycle is stabilized by the same control device G, and Figure 11 is the output port when using the control circuit shown in Figure 8. FIG. 12 is an output voltage-flow characteristic diagram showing changes in flow rate when stabilizing the refrigeration cycle in the same control device. 3...Thermoelectric expansion valve, 3H...Electric heater, 5...First temperature sensor, 5a...
...First thermistor, 6...Second temperature sensor, 6a...Second thermistor, 7...
・Electronic side device, 15...LSI. 16...Timer control circuit, 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 The thermoelectric expansion valve is made of a valve body whose opening degree is controlled depending on the degree of curvature, and is further provided with an energization amount control device that controls the amount of energization of the electric heater, and this energization amount control device is connected to the electric heater. and an output means for controlling the output voltage stepwise in the direction of increase or decrease by D/A conversion, and a first temperature detection device provided at the inlet or intermediate portion of the evaporator and converting the refrigerant temperature into an electrical signal. a second temperature detecting means provided at the outlet of the evaporator and converting the refrigerant temperature into an electrical signal, and comparing the magnitudes of the electrical signals from the first and second temperature detecting means to generate two control signals. a first output mode for controlling the output voltage of the output means stepwise in the direction of increasing or decreasing; and a first output mode for controlling the opening degree of the thermoelectric expansion valve in a direction opposite to the first output mode. a storage means storing second output modes for controlling the output mode alternately in the same direction from
a clock means for measuring variable control time of the output voltage in the first output mode and the second output mode; a reversal detecting means for detecting reversal of the output of the comparing means; a clock signal of the time measuring means and reversal detection; A transition means for sequentially shifting the output mode of the storage means according to a reversal detection signal of the means, and an output control deviation means for making a conversion amount of the output of the output means in the opposite direction larger than a value continuously output in the same direction. Refrigerant flow control device for refrigeration cycle.