JPS5888554A - Controller for refrigerating cycle - 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 The present invention aims to maintain the refrigeration cycle efficiently at all times in a refrigeration system or air conditioner H using an electric expansion valve such as a thermoelectric expansion valve. The objective is to detect the condition and stably control the refrigeration cycle using an electric expansion valve to achieve 1M optimization.

Conventionally, one method of optimizing the refrigeration cycle is to maintain the difference between the temperature of the evaporator and the temperature of the mold-filled part of the compressor, that is, the degree of superheat (superheat and one), at a predetermined value. It has been adopted.

Conventionally, in this type of control device, in order to maintain the superheat degree at a set value tcM, a method has been considered in which proportional integral or proportional integral derivative mva is continuously performed according to the value of the deviation. This method has good characteristics under stable @ control conditions, but on the other hand, there are cases in which the degree of superheat changes in response to changes in the state of the refrigeration cycle, which are slow on the order of 6 minutes or fast on the order of seconds. There is also a problem with the response speed of the expansion valve, and it is extremely difficult to configure a MA device to always maintain the degree of superheat at the set value in response to these situations. Changes in the load status of the refrigeration cycle, etc.

Depending on the condition of the spears, the superheated aim often causes a large vibration phenomenon, and stable control has not been achieved.

Conventionally, in order to alleviate the above problems, the degree of superheating is compared with the set value, and detection is performed in two positive and negative regions.

Some devices add or subtract the voltage applied to the expansion valve by a predetermined value at predetermined time intervals or when the sign changes depending on the sign. In this method, the degree of superheat control is basically in an oscillating state, but if the load on the refrigeration cycle is large (and the refrigerant flow rate is large), the degree of superheat can be controlled to be approximately equal to the set value. However, when the refrigeration cycle is operated under a low load, that is, when the refrigerant flow rate is low, large vibrations occur, making it easy for liquid to back up into the compressor.

If an attempt was made to improve the control performance under low loads, the control response under normal conditions would become extremely slow, and the system would also have problems in terms of stability and efficiency.

The present invention aims to eliminate the conventional problems as much as possible, stably control the degree of superheating, and improve the efficiency of refrigeration and air conditioning equipment (so-called ICLM, 81111) by improving the efficiency of the refrigeration cycle.

In particular, the present invention takes into account the advantages over the conventional methods described above,
The difference between the degree of superheating and the set value, that is, the deviation, is divided into three or more regions (previously two regions, positive and negative), and a method is provided to change the amount of output change according to the magnitude of the deviation performed in LA and proportional control. The present invention provides a refrigeration cycle control device that achieves early stabilization and suppresses the amplitude of oscillation, thereby always achieving optimum operation of the refrigeration cycle.

The configuration of the refrigeration cycle kIII-device of the present invention will be explained below based on the drawings. FIG. 1 is a block diagram showing one embodiment of a refrigeration cycle control device based on the present invention, and particularly shows the case where it is used in a cooling device.

In Figure 1, (1) is a compressor, (2) is a condenser, (
2) is a condenser (shungetsu blower), and (2) is an expansion valve whose opening degree can be adjusted by an electric signal (in this case, it is a thermoelectric expansion valve).

(ri is the evaporator, (6) is the blower for the evaporator (6), (υ
Inputs the temperature signal from the temperature sensor installed at the inlet of the evaporator (5), (2) the temperature sensor installed at the suction section of the compressor, and (9) the temperature sensor (wa and wa). , expansion valve-)
This is a control circuit that outputs an electrical signal (DC voltage) to the

FIG. 8 is a structural sectional view showing the internal structure of the expansion valve (4) shown in FIG. 1. In the first intention, @ is an expansion valve (4-inch case, @ is an electric heater, and @- is a bimetal.

Bimetal @- is a pair.

The electric heater tube is mounted on a bimetallic plate, which is held parallel by a plate support. Pi and metal are for atmospheric temperature correction. Control is a terminal.

A DC voltage supplied from the f1i11111 circuit (9) is connected.

2) is a spindle connected to a bimetallic body, 2 is a spring that pushes the spindle upward, and 2 is a seat that serves as a valve seat for the spindle. This expansion valve (4) is
When DC voltage is supplied smoothly to the electric heater, the bimetallic
is heated, and due to the deformation of the bimetal, the plate,
Via bimetal.

on the spindle) downwards. The spindle (2) is balanced at a position corresponding to the magnitude of the DC voltage by the stress of the spring and bimetal ring and the pressure of the refrigerant, which gives the degree of opening of the refrigerant passage and changes the refrigerant flow rate. The structure shown in Figure 2 is a closed energized type, and if the DC applied voltage (this is V) that is supplied to the expansion valve 4) is increased, the refrigerant flow rate (this is Q) is decreased, and Then, the refrigerant flow rate Q is increased.A characteristic example of the refrigerant flow IQ with respect to the applied voltage v is shown in Fig. 811. In the figure.

QL and Q indicate the minimum and maximum range of the refrigerant flow rate Q when the compressor (1) is operating, and the reason there are two curves is because of the hysteresis characteristic.

Therefore, in the configuration shown in Fig. 1, the refrigerant is compressed by the compressor (υ) into the condenser (2),
), evaporator (-), and compressor (circulates through the suction path of υ and outputs cooling capacity to the evaporator). In the operation of this refrigeration cycle, ideally, the most efficient operating state is when the refrigerant evaporated in the evaporator (5) becomes dry saturated vapor at its outlet. However, in the actual configuration, there is a temperature drop due to the passage resistance of the refrigerant piping inside the evaporator and from the evaporator to the suction part of the compressor (1). In order to prevent suction and liquid compression in the liquid mixing area (although this is not necessarily the case if an accumulator is provided), it is appropriate to operate the refrigerant gas in a slightly superheated area. Therefore, in order to achieve such an operating state, temperature sensors (ゎ and (
6) The difference between the detected temperatures (this is called the superheat degree SM)
The amount of refrigerant is controlled by changing the voltage mi applied to the expansion valve (4) so that the set value Sad (for example, the number 4@M, although it varies depending on the refrigerant piping) is always equal to the set value Sad.

Note that the degree of superheat of 3 Rin is not a degree of superheat in the strict sense (superheat), as there is a temperature drop due to passage resistance of the refrigerant piping as mentioned above, compared to that in an ideal refrigeration cycle, but here, It is assumed that the values obtained by temperature sensors (7) and (8) shown in FIG. 1 are shown.

Next I! The configuration of the l sister circuit (9) is shown in FIG. In FIG. 4, (6) is an area determination section, (b) is an arithmetic processing section,
@ is a signal output section, which is composed of a microcomputer (hereinafter referred to as microcomputer) (Ll), which includes all of the arithmetic processing section (B), the area determination section (H), and a part of the signal output section (6).
Area judgment department God is in addition to part of the microcomputer box.

Resistor-side differential amplifier, D/mu converter (b), comparator (
(to). The signal output section (6) includes a part of the microcomputer, a D7 MU converter CJS, and an operational amplifier So.

It consists of a resistor and a transistor (2).

In this configuration, the operation of the area determination section So is explained as follows.
From the temperature sensor (υ and resistor (b)), the voltage V at the inlet of the compressor (1) corresponding to the temperature T at the inlet of the evaporator (from the temperature sensor (υ) and the resistor (b)) is A voltage v3 corresponding to the temperature KiS is obtained and input to the differential amplifier (to), respectively. This differential amplifier (b) amplifies and outputs the difference between voltage ma8 and Vt, and its output is determined by superheat degree siis.
This value corresponds to mts-TIE. Here, if the set value of superheat degree is SM-, then the deviation ΔSH is ΔSH-sM
-8lid. As shown in Figure 6, the area M of the deviation ΔSH is set to 4 areas (MU1.MU2.MU1.A4), and the boundaries are defined as ΔSH.
”-2h6.0. +L646 rin.

Therefore, by using a microcomputer, ΔSH Fuji, iL5. O,
+154a, each inputs a digital amount of 5H4+ΔSH into the D/MU conversion 1mH, and its output Sm
Compare 1l (asH4+M1i1) and superheat degree SMWi
By comparing by t@.

The difference between the superheat degree ssi and the set value IHm at that time, that is, the area of the deviation ΔSH, is determined. The four regions shown in FIG. 6 are centered around the deviation Δ$-0-1, with two regions for each of positive and negative values.

Next, the operation of the arithmetic processing section (b) will be explained. Arithmetic processing unit (
b) is the deviation ΔS divided by area judgment @rJ4
Due to the area H, the expansion valve (4
) is used to determine the value of the applied voltage v1.

This arithmetic processing unit @ is used when the area ^ changes (for example, from Mu 1 to Mu 4, etc.) and when the same area ^ changes for a predetermined time (for example, 2
minutes), the increase/decrease t-1 corresponding to each state, that is, the change in intensity for changing the applied voltage VT, is added or subtracted from the value of the applied voltage τ up to that point, and the applied voltage to be newly output is determined. Determine the value of MaT. In this case, increase/decrease C
is as shown in Table 1, for example. "MuF" in the table
indicates the area when the previous applied voltage VT change process was performed, the symbol "Mr" indicates the area in which the current applied voltage VT change process is performed, and in the case of MF to Mt, the area This is a case where the time has changed, and the case where a predetermined time has elapsed in the same area ^ is the case where M V - M r is the same.

Table 1 For example, the increase/decrease growth can be expressed in concrete numerical values as shown below.

sB ” !5smmaCyi, -wrinkle 5・-V su,exp 60pengmaCng Opengma8g -1o・wama and tL et al., the area where the absolute value of the deviation ΔS! is large, that is, the lees, A4 is that small area, ie mu,
, A11C, the increase/decrease e in time for M1-M is set to a large value (mHl > s!l). This is similar to line 1 in proportional control (method #c'I/A of giving the amount of change in response to a large deviation hs. The larger the deviation Δill, the larger the increase/decrease jis, and the larger the corrective action. This is to make the deviation Δ5M-0-1 quickly. Also, in the operation of ^F~Mude, from Al to A2 or M1
to A1, that is, when the $J deviation Δ8M changes from a large region to a small region, the increase/decrease is treated as 2-0 theory, and the opposite case is distinguished from the increase/decrease of −5 gImV. This is because the direction in which the deviation N1 changes is ΔSum 04·, which is a desirable characteristic.

This is to prevent the superheat degree sii from falling into an oscillating characteristic if the opening is set to 'alt' at this time, causing the overheating to become too thick.

Also, the area is A! The increase and decrease C when changing from A1 and Mue to Mui is 100 mV. This is a change in which the deviation Δ■ is approximately an appropriate value, so no corrective action is taken. Input that is appropriate! As shown in Fig. 8, the relationship between the applied voltage v1 of the tension valve (4) and the refrigerant flow rate Q has a slight hysteresis characteristic, and the deviation Δ5H=Od@Rin is the boundary for this region M^ 1.
Mu, is an addition process, Mutom 6 is a subtraction process, so in this case, considering the subsequent processing, it is assumed to be 10GmV,
This gives an increase or decrease corresponding to hysteresis.

By the above operation, the arithmetic processing unit (b) sets the new applied voltage MAT to VT■, assuming that the applied voltage after the previous change is VTF.
VTF±e (+ means addition, - means subtraction) Next, the signal output section (2) converts the digital signal of the value of the new applied voltage FEvt given by the arithmetic processing section (b) into a D/A Input the voltage to the converter and apply the output voltage to the expansion valve (a) using the operational amplifier transistor (to).The voltage applied to the expansion valve (47) is calculated by the arithmetic processing IIA (b). Until a new addition/subtraction process is performed, fC always remains at the previously given value.

Due to the above! Although the configuration and operation of the control circuit have been explained, characteristic examples such as the deviation A51 of the degree of superheating when the device shown in Figure 1 is operated using the control circuit (9) of Figure 4 are shown in Figure 6.
As shown in the figure. #j6 Figure (1) shows the characteristics when the refrigerant flow rate is low and the air volume of fan <8> is the lowest, and (h) shows the characteristics when the air volume of fan (2) is the maximum and under standard conditions. It is a characteristic. Also, the superheat degree setting value is the same as fc SH
It is about dm4d@g.

In the figure, (a) (and (Xun)'s t-ri both have the same area and indicate a predetermined darkness when changing the applied voltage Vτ, and t4-"2 minutes 12 seconds, ts" 2 minutes (so
f'Lwt source frequency 501g, 60Hz reference (l
jri) ToL.

Ta.

As is clear from the figure, the variation of the deviation ΔSH in a stable state is better in (1), and (s) is an oscillation of about ±1−·l. It is desirable to make it more constant, but (
Even in the case of a), this level of vibration does not cause any problems in the refrigeration cycle, and is almost satisfactory in terms of efficiency.

Note that (in -, stable state -, increase W4 ji c=s
However, the area changes to MU2 and MU (the sign of the deviation Δ8M is negative), but this is because the axis is slightly larger than the hysteresis width shown in Figure 8, and + ejll is set to a slightly smaller value. In addition, in order to further improve the (head) characteristics, @11 may also be set to a slightly smaller value. However, if the e-sieve described above is made smaller, the response at (-) may become worse.
It is desirable to select

Here, in the 1 table of increase/decrease C for the area ^, @n■1 (although it is set as 01 Pengma* "H-Om
In addition to the increase and decrease corresponding to the hysteresis, ・a”
1091a, and the movement can be added to each increase/decrease C only when the current process is the reverse of the previous addition/subtraction process.In this case, regardless of the change '4 in the area ^, The present invention can be applied even when the applied voltage v'r is changed by a predetermined value, and the applicable range is expanded.

Next, FIG. 7 shows a case where the number of area divisions in the area processing section (to) is increased. In the figure, the deviation ΔSHm
It is divided into a total of 8 areas of 14·g each with Od@g as the center. Specific examples of increases and decreases e for these areas are shown below. In this Table 2, both areas A4 and A5 are considered as so-called dead zone areas, and even if a predetermined time passes in this area or changes to this area from other areas, the voltage equivalent to hysteresis is 100 mV (from Mu4). Except when changing from MU1 to MU4), the increase/decrease is always assumed to be ``e'' and ``o''. Therefore, as long as this dead band region is 1, the applied voltage VT will not change except for a change of 1 oom corresponding to the hysteresis.For example, when changing from A to MU, 29m, when a predetermined time elapses in A1, increase or decrease when the area changes, and the larger the absolute value of the deviation Δ11H, the greater the increase or decrease. In addition, if the absolute value of the -difference ΔsWN changes from a large area to a small area,
The increase/decrease is basically zero, but the deviation ΔSH
A slight increase/decrease is given only in the case of A1 from the largest AI and M1 from M1, in order to improve responsiveness.

Area determination unit (a) and arithmetic processing unit based on this Fig. 7
Since the value of the degree of superheating sI can be detected in detail from the operation iζ, controllability is further improved (
Stability, responsiveness, efficiency) can be expected.

In addition, in the increase/decrease e based on Fig. 7, Nysteresis Kirito e6-Zoo■ma is given when changing from Mu to A5 or from Mu diagnosis to A4, but as another method, the previous increase/decrease e This time from addition and subtraction processing where is not zero.

The process is the opposite of the previous one, and only when the increase/decrease e is not zero, add eo corresponding to hysteresis to the increase/decrease ζ. In System S, the applied voltage is not changed at all. These methods are preferably determined depending on the state of controllability.

Next, FIG. 1 shows an example of the simplest area division having a dead zone area. This figure is a highly simplified version of the one shown in FIG. 7, and the dead zone area is ^. In this case, although the controllability is inferior to that shown in the diagram, the configuration of the area determination member and the operation of the arithmetic processing unit (b) are simpler. In addition, the increase and decrease e・ corresponding to the hysteresis in FIG. 7 is given by the area
In the case where the number has changed to 2, it is time to perform addition and subtraction processing that is the opposite of the previous one.

Although the refrigeration cycle control device based on the present invention has been described above using the embodiment shown in the drawings, the following configurations are possible in addition to this embodiment.

1) Temperature sensors (7) and (8) are evaporating! !
(Any position from the inlet to the middle of the season, the evaporator (5
) can be placed at any position from the outlet of the compressor (IJ) to the inlet of the compressor (IJ).If the relationship between the detected temperature and the degree of superheat at each position is determined and the set value is given, Similar operations are possible.

2) 8112 circuit (In the current example, the microcomputer O was used as the main component, but it is also possible to use other digital integrated circuits or analog circuits.

8) As the expansion valve (4), a so-called thermoelectric expansion valve shown in FIG. In addition, as the characteristics of the expansion valve (4), as shown in the HS diagram, we have explained iζ and Eζ when it has hysteresis characteristics, but it is better if this hysteresis characteristic can be almost ignored or there is no hysteresis. In the arithmetic processing unit (b), the increase/decrease c corresponding to hysteresis is calculated.

It is no longer necessary to feed the plant, and the processing becomes narrower.

4) In the region determination section (10), in the configuration where the degree of superheating SH and the comparison data $111 are compared, if a differential is given to the comparator (to) or the comparison data sIm, malfunctions at the time of region determination can be reduced. , it becomes possible to make reliable judgments.

Alternatively, the temperature signals T and S detected by the temperature sensors (7') and (8) may be directly converted into digital signals by a ^/D converter, and the area can be determined based on these signals, reducing the cost. In terms of performance, etc., it is desirable to select according to the intended use.

6) In the example, the characteristics and operation were explained in a situation where the degree of superheat BH is relatively stable. However, when the compressor (1) is stopped or immediately after starting, the applied voltage VT to the expansion valve (4) is maintained at a predetermined constant value #C (including fully open), and the refrigeration cycle is relatively stable after starting the compressor (1), that is, at the point when several minutes have passed from starting the compressor (υ), Example Cζ is shown. Stability control can be achieved either by performing a control operation or by increasing or decreasing the applied voltage VT by a predetermined value at regular time intervals until the deviation Δ$■ reaches a predetermined value, and then by performing the tIl gentle operation shown in the embodiment. - It will be possible to transition to the first state reliably and quickly.

the law of nature! Figure 1 shows the air conditioner.

In addition, it is clear that it can be applied to heat pump type air-conditioning equipment and refrigeration equipment, and it is expected that it will contribute to increasing the efficiency of equipment for both.

The refrigeration cycle @ pure device of the present invention has been explained in detail above.According to the present invention, the difference between the degree of superheating and its set value, that is, the deviation, is detected in at least eight regions, and the state is detected. Accordingly, the electric signal to the expansion valve is finely changed by a predetermined increase/decrease.
In a characteristic.

Its stability and responsiveness can be sufficiently improved.

The refrigeration cycle can be maintained efficiently at all times. In addition, it is expected to improve the efficiency of the freezing cycle, especially the improvement of the SG fuyaku, and it can have an extremely excellent effect in terms of energy saving.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an embodiment of a refrigeration cycle control device based on the present invention, FIG. 2 is a structural sectional view showing an example of the expansion valve in FIG. 1, and FIG. 8 is a structural diagram of an example of the expansion valve shown in FIG. Characteristic diagram,
Fig. 4 is a #1 diagram of the control 112 circuit in 1E, Fig. 6 is a diagram of the area division detected by the area determination unit, and Fig. 6 (Xu and (b) are Figs. 1 to 1). 7 and 8 are explanatory diagrams of other embodiments of the area classification detected by the n area determination unit. (υ-・Compressor, -) -Condenser, (4 doors...expansion valve, ψ
) - Evaporator, (7 units/1st temperature sensor, (8) - 2nd
Temperature sensor, (11) - control circuit, Ql - area determination section, (b) - arithmetic processing section, Iwa - signal output section, DI -.
・Microcomputer 1 Figure 3 Figure 4 Figure 5 ASH (・5H-!;Hd) Figure 6 e.

Claims (1)

[Scope of Claims] 1. An expansion valve whose throttle amount can be adjusted by an electric signal, a first temperature sensor provided at the inlet or intermediate portion of the evaporator, and an outlet of the evaporator or the suction portion of the compressor. The control circuit is comprised of a second temperature sensor provided in the second temperature sensor, and a control circuit that inputs the temperature signals from the @l and second temperature sensors and issues an electric signal to the expansion valve. a region determination unit that compares the difference between the two temperature signals and its set value and divides the deviation into at least eight or more regions; and when the region obtained by the region determination unit changes or is the same region. an arithmetic processing unit that adds or subtracts a predetermined increase or decrease corresponding to each state every time a predetermined period of time elapses, and determines the value of the electrical signal to be sent to the expansion valve; A refrigeration cycle fi! comprising a signal output section that outputs to the expansion valve. lI! I device. L is a tension valve, a control grip path Q is supplied with an electric signal emitted by an electric heater, a bimetal that deforms due to the heat generated by the electric heater, and a spindle that liquefies the refrigerant passage through deformation of the bimetal. A refrigeration cycle control device according to claim 1.