JPS61202052A - Refrigerator with electric type expansion valve - 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 (Field of Industrial Application) The present invention relates to a refrigerator equipped with an electrically operated expansion valve, and more specifically, an electrically operated expansion valve that is provided on the inlet side of an evaporator and whose opening degree can be adjusted. superheat degree detection means for detecting the degree of superheat of the refrigerant on the outlet side of the evaporator; and based on the output of the detection means, the valve opening degree of the expansion valve is adjusted so that the degree of superheat of the refrigerant on the outlet side becomes a set superheat degree. The present invention relates to a refrigerator including a control means for controlling the refrigerator.

(Prior technology) Generally, a refrigerator has an expansion mechanism such as a capillary tube or a temperature-sensitive expansion valve installed in the liquid pipe on the inlet side of the evaporator to superheat the suction gas refrigerant at the outlet side of the evaporator. I'm trying to adjust the degree.

(Problems to be Solved by the Invention) By the way, when a conventional refrigerator that uses the capillary tube or temperature-sensitive expansion valve as the expansion mechanism for controlling the degree of superheat is applied to a heating device, it is possible to The drawback was that it was not possible to obtain good rise characteristics. This point will be explained below with reference to FIG. 10 regarding a separate refrigerator using a temperature-sensitive expansion valve as the expansion mechanism.

In winter, the outside temperature is lower than the indoor temperature, so when the operation is stopped, the refrigerant is in the evaporator (51) and accumulator (52).
) etc. are concentrated on the outdoor unit (A) side.

When the operation is started in this state, the evaporator (5 units) and the accumulator (52 units) and the accumulator (52 units) are
), the degree of superheat of the suction gas refrigerant becomes zero (i.e., saturated), and therefore the expansion valve (50)
The valve opening is adjusted to an extremely small opening. For this reason, the amount of refrigerant circulation is suppressed, making it difficult to obtain an appropriate refrigerant distribution within the refrigerant circuit, and as a result, there is a problem in that good start-up characteristics cannot be obtained at the start of operation.

In addition, in FIG. 10, (53) is the expansion valve (50).
temperature sensing part, (54) is a compressor, (55) is a condenser, (5
B) is a liquid receiver.

Furthermore, even in refrigerators using capillary tubes, the tubes cannot be adjusted to actively reduce the resistance at the start of operation, so there is a similar problem of poor start-up characteristics.

Therefore, an object of the present invention is to forcibly adjust the expansion valve to a large opening at the start of operation to increase the amount of refrigerant circulation in a refrigerator using an electric expansion valve as the expansion mechanism. The objective is to quickly optimize the refrigerant distribution and obtain good start-up characteristics.

(Means for Solving the Problems) The structure of the present invention will be explained based on FIG. 1 and FIG. a valve (EV), a degree of superheat detection means for detecting the degree of superheat of the refrigerant on the outlet side of the evaporator (2), and a degree of opening of the expansion valve (EV) on the outlet side based on the output of the detection means. In a refrigerator equipped with a control means for controlling the degree of superheat of the refrigerant to a set degree of superheat, the valve opening of the expansion valve (EV) is set to be larger than the opening during standard operation upon input of an operation start signal. An initial opening degree setting means for forcibly setting the opening degree and a canceling means for canceling the valve opening degree setting of the expansion valve (EV) by the setting means are provided.

In addition, in FIG. 2, the evaporator (2) is shown as a heat source side heat exchanger.

Further, the canceling means detects optimization of the refrigerant distribution in the circuit based on a change in the degree of superheating of the suction gas refrigerant in the refrigerant circuit, and cancels the valve opening degree setting by the setting means. . Moreover, the cancellation of the valve opening degree setting by the cancellation means may be performed based on the passage of time from the start of operation.

(Function) At the start of operation, the expansion valve (EV) is forcibly held at a large opening, so the refrigerant circulation amount can be increased regardless of the degree of superheating of the suction gas refrigerant, and as a result, the refrigerant distribution is can be quickly optimized, and therefore good start-up characteristics can be obtained even during heating operation.

(First Embodiment) The refrigerator shown in FIG. 2 is one in which the refrigerator according to the present invention is applied to a heating device, in which a compressor (1) is installed in an outdoor unit (A).
, a heat source side heat exchanger (2) that acts as an evaporator, and an electrically operated expansion valve (hereinafter referred to as an electrically operated valve) (EV) that controls the degree of superheating of the suction gas refrigerant are sequentially connected.
A user-side heat exchanger (3) that acts as a condenser is installed in the indoor unit (B), and these outdoor units (A) and indoor units (B) are connected by connecting pipes (C), and the refrigerant are circulated as shown by solid arrows.

Further, each of the heat exchangers (2) and (3) is of the air type, and each is equipped with a fan (F, > (F□)).

Note that (4) is a liquid receiver, and (5) is an accumulator.

Further, the valve opening degree of the electric valve (EV) is controlled as follows.

That is, a first temperature detector (7) for detecting the temperature of the suction gas refrigerant is attached to the suction gas pipe (6) that connects the heat source side heat exchanger (2) and the compressor (1). , the liquid receiver (4) and the suction gas pipe (6) are connected by a detection circuit (9) having a capillary tube (8), and the detection circuit (9) includes a capillary tube (8). A second temperature detector (10) on the outlet side that detects the saturation temperature equivalent to the evaporation pressure
A microcomputer to be described later calculates the degree of superheating based on the detected temperatures of these detectors (7) and (10),
Based on this result, the degree of superheat is adjusted to the desired set degree of superheat (S
The valve opening degree of the electric valve (EV) is pulse-controlled so that the electric valve (EV) becomes HO).

In this embodiment, the control means for controlling the degree of superheating of the electric valve (EV) is configured using a microcomputer as described above.

Hereinafter, a control circuit for the refrigerator using this microcomputer will be explained based on FIG. 3.

The M microcomputer (11) is normally (7) M, so it consists of a central processing unit (12) and a memory (13) consisting of ROM and RAM, and an A/D converter (14) is connected to the input side. and said first and second temperature detectors (7) (1
0), and also an operation switch (15) and an indoor thermostat (16). Further, on the output side, drive circuits (17) and (18) connect the electric valve (EV), the drive motor (M) of the compressor (1), and each of the fans (F,) (F,), respectively. They are connected via (35) and (36).

In the refrigerator configured as described above, the operation start signal output from the operation switch (15) and the thermostat (16) is input, and the valve opening degree of the electric valve (EV) is adjusted to the opening degree during standard operation. a setting means for forcibly setting the opening degree (2α) (hereinafter referred to as the initial opening degree) that is twice the opening degree (α);
After the start of operation, a canceling means is provided for detecting that the degree of superheating first changes from above the set superheating degree (SH8) to below, and canceling the setting of the valve opening degree by the setting means.

All of these means are achieved using the microcomputer.

In this embodiment, the canceling means determines an appropriate refrigerant distribution within the refrigerant circuit based on a change in the degree of superheating of the suction gas refrigerant, and cancels the valve opening degree setting by the setting means. It will be explained in advance that the appropriate distribution of the refrigerant in the circuit can be determined based on the change in the degree of superheating.

The present inventors have found that when the opening degree of the expansion valve is forcibly set to a large opening degree at the start of heating operation, the relationship between the change in degree of superheating and the refrigerant distribution is roughly as follows. This was experimentally determined (see Figure 9). That is, at the start of operation, since the liquid refrigerant is stored in the accumulator (5), the degree of superheat is zero (saturated state). (Status ■ to ■) With the start of the operation, the stale refrigerant in the accumulator (5) is sucked into the compressor (1), while the gas refrigerant discharged from the compressor (54) is transferred to the user side. Since not only the heat exchanger (3) but also the connecting pipe (C) and the indoor refrigerant pipe are at a low temperature, the indoor unit) (B)
It gradually stays on the side. As a result, the refrigerant is biased toward the indoor unit (B), and the degree of superheating of the suction gas refrigerant increases, and this degree of superheating (SHo) becomes larger than the set degree of superheating (
Condition ■～■).

Eventually, as the operation continues, the condensing pressure increases, and as a result, the liquid refrigerant that had accumulated in the user-side heat exchanger (3) gradually returns to the accumulator (5) side, and as a result, The degree of superheating is decreasing again (state ■ ~■
).

In this way, the refrigerant is transferred to the outdoor/indoor units (A) (B).
), and the superheat degree becomes the set superheat degree (S
It was confirmed that the refrigerant distribution was almost in an appropriate state when the temperature was below HO).

Therefore, by detecting the degree of superheating of the suction gas refrigerant, it is possible to indirectly determine the state of good refrigerant distribution.

Hereinafter, the program to be installed in the computer (11) will be explained based on the flowchart of FIG. 4, and the operation of the refrigerator will also be explained. (Please refer to FIG. 9) When the power is turned on, the electric valve (EV) is closed, and the valve opening of the valve (EV) is adjusted to zero point (from step 1001 onwards, the word "step" is used). omitted).

Next, the signals from the indoor operation switch (15) and thermostat (16) are read (101), and it is determined whether to operate or stop (102).

If both the operation switch (15) and the thermostat (16) output ON signals, it is determined whether the operation has started or not.
It is determined whether the operation is to be continued (103), and if the operation is to be started, the valve opening of the electric valve (EV) is set to the initial opening (2α) (104), and the compressor (1) is driven (105). .

Then, the operation is continued for 3 minutes with the electric valve (EV) maintained at the initial valve opening degree (108).

On the other hand, if it is determined in step (103) that the operation is continued, the step (104, 105) is skipped and the process proceeds to step (106).

Then, after 3 minutes have elapsed, each of the temperature detectors (7) (1)
The temperature of the suction gas refrigerant and the saturation temperature equivalent to the evaporation pressure are read from 0) (107), and the degree of superheating is calculated based on these temperatures, and the change valve opening degree of the electric valve (EV) is calculated based on the degree of superheating. (108) (Hereinafter, the detected superheat degree is SH
).

The reason why the degree of superheat is not calculated for 3 minutes after the start of operation is that even if the degree of superheat is detected during this period, the value is extremely unstable and unreliable. This is because the distribution will never be appropriate.

At the same time, the electric valve (EV) has an initial opening degree (2α).
109), if the initial opening is (2α) (at the beginning of operation), whether the detected superheat degree (SH) has changed from above the set superheat degree (SHo) to below. , in other words, these deviation values (E=SHo-8)I)
It is determined whether or not has changed from negative to positive (110).

If the deviation value (E) remains positive (Fig. 9 ■~■
), when it changes from positive to negative ((3)), and when it remains negative (■ to ■), the process returns to step (101) and the above routine is repeated.

Therefore, in the step (110), the deviation value (E)
When changes from negative to positive (around 0), that is, when the detected degree of superheat (S) () changes from more than the set degree of superheat (S) Io) to less than the set degree of superheat (S), the refrigerant distribution in the refrigerant circuit It is determined that the valve opening degree of the electric valve (EV) is almost suitable, and the valve opening degree of the electric valve (EV) is adjusted to the changed valve opening degree (111).

Once the valve opening of the electric valve (E'V) is adjusted, since this valve opening is much smaller than the initial valve opening (2α), in the step (IO2), r N is always
When it is determined that the engine is OJ', the process jumps to step (111) and the superheat degree control by the electric valve (EV) is continued.

Note that step (112) is a step for instructing to stop operation or standby.

As described above, since the electric valve (EV) is forcibly held at a large opening at the start of operation, the amount of refrigerant circulation can be increased regardless of the degree of superheating of the suction gas refrigerant, and as a result, the refrigerant distribution can be quickly adjusted. Moreover, this optimization of the refrigerant distribution can be detected based on the degree of superheat, and the electric valve (E
Since the superheat degree control of V) can be started, good start-up characteristics can be obtained even during heating operation.

In the above embodiment, the change in the degree of superheating is directly detected, and the setting of the initial opening degree is canceled by the canceling means based on this change. It is also possible to experimentally obtain a time period in which the time period for which the time period is 1000 is reached, and then use a timer or the like to cancel the setting by the setting means.

(Second Embodiment) What is shown in FIGS. 5 to 8 is an example in which the refrigerator of the present invention is applied to a multi-type air-conditioning device.

The basic configuration of the refrigerant circuit is explained based on FIG. Side main pipe (22)
Multiple harmonic branch pipes (23) branching from the gas side main pipe (
24) and a plurality of gas side branch pipes (25) branching from this gas side main pipe (24).
and a user-side heat exchanger (3) and a fan (F,),
It consists of a plurality of indoor units (B) connected in parallel between the harmonic branch pipe (23) and the gas side branch pipe (25) via a plurality of connecting pipes (C), and Heating and cooling operation is possible by switching the road switching valve (21).

What is shown in FIG. 5 is a multi-type air conditioning system configured as described above, in which first electric valves (EV, -EV,) are respectively interposed in the wave harmonic branch pipes (23), and the A second electric valve (EV, ) is interposed in the side main pipe (22), and a liquid side main pipe ( 22) is interposed with a liquid receiver (4). Note that (2B) is a dryer.

The control circuit for the refrigerator is shown in FIG. 6, but since it is basically the same as the first embodiment shown in FIG. 4, the explanation will be omitted. In addition, (28) in Fig. 6 is the multiplexer 1 (31 to
34) are respective drive circuits.

The first electric valve (EV, -EV,) controls the degree of subcooling of the high-pressure liquid refrigerant on the outlet side of each user-side heat exchanger (3) during heating operation, and controls the degree of subcooling of the intake gas refrigerant during cooling operation. It acts as an expansion mechanism to adjust the degree of superheat.

Similarly, the second electric valve (EV) adjusts the degree of superheating of the suction gas refrigerant during heating operation, and adjusts the degree of subcooling of the high-pressure liquid refrigerant during cooling operation.

The first and second electric valves (EV, -EV4) mainly use a pulse motor that rotates by a certain angle with one pulse, and are configured so that the valve opening degree can be adjusted by a transmission pulse signal output from a micro combinator. are doing.

Here, to explain the correspondence between the configuration of the present invention and the configuration of this embodiment, during heating operation, the heat source side heat exchanger (2) corresponds to the evaporator of the present invention, and The second electric valve (EV4) corresponds to the expansion valve (EV) for superheat degree control in the present invention.

Similarly, during cooling operation, the user-side heat exchanger (
3) corresponds to the evaporator in the present invention, and the first
The electric valve (EV□~S) is an expansion valve (EV) for controlling the degree of superheating.
It corresponds to

The following explanation will be limited to the heating operation.

The degree of superheat control by the second electric valve (EV4) is the same as in the first embodiment, and the first and second temperature detectors (7) attached to the suction gas pipe (6) and the detection circuit (9) (10)
A microcomputer calculates the degree of superheating based on the output of
Based on this calculation result, the valve opening degree of the second expansion valve (EV) is controlled.

In addition, the valve opening degree of the first electric valve (EV, ~,) is not controlled by directly detecting the degree of supercooling of the high-pressure liquid refrigerant, but is first controlled in accordance with the number of operating indoor units (B). Initial setting (for example, 150 pulses for single room operation,
100 Hulst in 2-compartment operation, and 70 in 3-compartment operation
After pulse), the temperature of each high-pressure liquid refrigerant is detected by each third temperature detector (27) attached to each wave harmonic branch pipe (23), and the temperature of each electric motor is adjusted so that these detected values are equal. valve(
EV, #3) valve opening degree is readjusted. The reason for this readjustment is to finely adjust the degree of subcooling, but it is mainly to prevent uneven flow of the refrigerant between the user-side heat exchangers (3).

However, other than the above-mentioned points, the differences in the configurations related to operation control between the second embodiment and the first embodiment are as follows.

■ The timing at which the second electric valve (EV) is changed from the initial opening setting to the normal superheat degree control is determined by the superheat degree (S).
H) becomes below the set superheat degree (SH,) and stabilizes at zero (Fig. 9 ■ to ■), and then further increases to above the set superheat degree (SHO) (■). do.

(2) The valve opening of the second electric valve (EV4) is controlled by PID. That is, the degree of superheat (SH) of the suction gas refrigerant is changed every 20 seconds.
This superheat degree (SH) and the set superheat degree (SH,
), and calculate the deviation value (EmSHO-SH) from each of the three times up to the current sampling (EO, E, , E,
), the second electric valve (
It is like calculating the change valve opening degree of EV4).

Changed valve opening = AX (El-E2)+BX E2+C
X (E2 - 2

Since the steps up to step (10'3) are the same as in the first embodiment, the explanation will be omitted.

Note that in step (104), the first electric valve (EV,
The opening degrees of the valves (~, ) are set to 300 pulses in the driving chamber and 120 pulses in the stop chamber, respectively, while the second electric valve (EV,
) is set to a much larger valve opening (350 pulses) than the opening during standard operation (170 pulses).

In step (120), the degree of superheating (SH) of the suction gas refrigerant and the deviation value (EmSHO-8H) are calculated based on the detected temperature read in step (107).

It is determined whether the second electric valve (EV4) is currently under PID control (121). At the beginning of operation, as described above, the valve opening degree of the second electric valve (EV) is set to a constant value, so at the beginning of operation, rNOJ is determined in step (121), and step control is selected (122).
).

Then, the deviation value (E: initial data is E.

) is loaded (12
3). Since it has not been read during the first sampling, the process proceeds to step (124) and the deviation value (E O) is read. After that, the process returns to step (101), and when it reaches step (123) again in the next sampling, it is determined that it is rYEsJ this time, and the process proceeds to step (125), where the deviation value (El) at that time is read (12El).
, Furthermore, in the same way, step (
125), and the deviation value (E, ) at that time is read in step (127).

At the time of the next sampling, the deviation value (Eo.

E,,E,) are also read, so step (1
Proceeding to step 28), it is determined whether the degree of superheating has stabilized based on the three deviation values (EO to E2). In addition, l Eo-E
l I + I El −Em l , IEo
-EmI < 1.5°C is considered stable.

As shown in FIG. 9, after the start of operation, until the state of ■ to ■ is reached, that is, the degree of superheat (SH) increases once and then decreases again until it reaches zero (saturation), the deviation is Value (E)
is not stabilized, so until then step (128)
Proceed to step (129) and set E to Eo, and
E to El.

and read E3 at the next sampling (127
).

Then, the state shown in Figure 9 ■ to ■ is reached, and step (12
When it is determined in step 8) that the deviation value is stable, the process proceeds to step (130), and when it is determined that the deviation value (E, ) is negative, the second electric valve (EV4
) is adjusted to the closed side by 20 pulses (131).

After this adjustment, these steps are repeated again, and in step (131), the second electric valve (EV) is sequentially adjusted to the closing side.

As a result, in step (130), the deviation value (
E) is determined to be positive, that is, the superheat degree (
When SH) becomes larger than the set superheat degree (SHO) (9th
In the state shown in Figure (2), it is determined whether the second electric valve (EV4) is at the initial opening or not, and since it is not already at the initial opening,
If the determination is NO, the valve opening degree of the first electric valve (EV1 to EV1) is reset in step (132). (1 room operation; 2
50 pulses, 2 chamber operation; 200 pulses, 3 chamber operation; 15
0 pulse) Then, PID control of the valve opening of the second electric valve (EV) is started (133).

This PID control is as shown in FIG. 8. The deviation value (E,) at that time is read (134), and the change valve opening of the second motor-operated valve (EV4) is calculated using the change valve opening calculation formula described above. 135) and change the valve opening degree. (
136).

After this, the first electric valve (EV, ~,) is also feedback-controlled for each valve in the same way, and the changed valve opening degree is calculated using the control formula (% formula %), and based on this, the 1 Adjust the electric valve (EV, ~,) (steps 136 to 144)
.

In addition, E- is the average value (t.) of the temperature (t+-3) of the condensate refrigerant detected by the third temperature detector (27) and the detected temperature corresponding to each of the electric valves (EV, ~,). (1+~,), and Eo-~E,'' is the connected 3
The deviation values at the time of sampling are shown.

(Effects of the Invention) As described above, the present invention provides an initial opening that forcibly sets the valve opening of the expansion valve (EV) to a larger opening than the opening during standard operation by inputting an operation start signal. Since the setting means and the canceling means for canceling the valve opening degree setting of the expansion valve (EV) by the setting means are provided, the refrigerant distribution in the refrigerant circuit at the start of operation, such as during heating operation, is uneven. However, extremely good start-up characteristics can be obtained, and normal operating conditions can be reached in a short period of time.

[Brief explanation of the drawing]

Fig. 1 is a diagram corresponding to the claims of the present invention, Figs. 2 to 4 are drawings related to the first embodiment of the present invention, Fig. 2 is a refrigerant circuit diagram, and Fig. 3 is a diagram corresponding to the claims of the present invention.
6 is a control circuit diagram, FIG. 4 is a flowchart showing a program to be incorporated into the microcomputer, FIGS. 5 to 9 are drawings related to the second embodiment of the present invention, and FIG.
FIG. 7 is a control circuit diagram, FIGS. 7 and 8 are flowcharts of programs to be incorporated into the microcomputer, FIG. 9 is an explanatory diagram showing operating conditions, and FIG. 10 is a refrigerant circuit diagram showing a conventional technique. (2)・・・Heat source side heat exchanger (evaporator) (EV)・
...Motor-operated valve (expansion valve for superheat control) (EV4)...Second motor-operated valve (expansion valve for superheat control) Fig. 4 Ko 5 Fig. 8 [Yes] Fig. 9

Claims (1)

[Claims] (1) an electrically operated expansion valve (EV) with adjustable opening provided on the inlet side of the evaporator (2); and superheat degree detection means for detecting the degree of superheat of the refrigerant on the outlet side of the evaporator (2); and a control means for controlling the valve opening degree of the expansion valve (EV) based on the output of the detection means so that the degree of superheat of the outlet side refrigerant becomes a set degree of superheat, the operation start signal being input. initial opening setting means for forcibly setting the opening of the expansion valve (EV) to a larger opening than the opening during standard operation; and A refrigerator equipped with an electric expansion valve, characterized in that it is equipped with a release means for canceling the temperature setting.