JPS62129669A - Drive controller for electric 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 drive control device for an electric expansion valve in a refrigeration system.

(Prior art) As a conventional drive control device for an electric expansion valve for a refrigeration system,
For example, the apparatus described in Japanese Patent Application Laid-Open No. 59'-205559 can be mentioned. This device detects the degree of superheat of the evaporated refrigerant, compares the detected degree of superheat with the reference degree of superheat, outputs a signal corresponding to the difference, and operates the electric expansion valve in response to this signal. This is to control the drive. Furthermore, the above device is configured to change the number of expansion valve drive pulses output per unit signal according to the difference in the degree of superheating, depending on the opening degree range of the electric expansion valve. That is, the operation gain is adjusted so that the number of drive pulses per unit signal is increased in the large opening range of the electric expansion valve, and the number of drive pulses per unit signal is decreased in the small opening range.

(Problems to be Solved by the Invention) However, the drive control device for an electric expansion valve as described above has the following drawbacks. This is because if you want to control the electric expansion valve as described above, that is, if you want to perform small-scale control even in a small opening range, you will need to use a motor with a small step angle per pulse. This means that the structure of the rotor and stator portions of the pulse motor becomes complicated, making the electric expansion valve and, by extension, the entire device expensive. It is also conceivable to use a pulse motor with a relatively large step angle and perform minute control using a deceleration mechanism, but in this case, the deceleration mechanism described above would be complicated and the entire device would be expensive. The problem arises that it becomes something else.

This invention was made in order to solve the above-mentioned conventional drawbacks, and its purpose is to provide an electric motor that can perform precise opening control even when using a pulse motor with a large step angle without incurring a cost increase. An object of the present invention is to provide a drive control device for an expansion valve.

(Means for Solving the Problems) Therefore, in the electric expansion valve drive control device of the present invention, superheat degree detection means 13 for detecting the degree of superheat of the evaporated refrigerant.
and a determining means 16 for determining whether or not the detected degree of superheat is close to the set degree of superheat according to item 2, and when the detected degree of superheat is far from the set degree of superheat. a step control means 18 for outputting a number of pulses to the electric expansion valve 5 according to the difference between the set superheat degree and the detected superheat degree, and when the detected superheat degree is close to the set superheat degree; Electric expansion valve 5 within the required time
An opening/closing control means 19 is provided for driving the opening and closing direction alternately by one step in the opening direction and the closing direction.

(Function) In the above-mentioned device, when the detected superheat degree is far from the set superheat degree, that is, when it is necessary to perform large opening control in the electric expansion valve 5, the same method as in the conventional device is used. The step control means 18 inputs a number of pulses corresponding to the difference in the degree of superheat to operate the electric expansion valve 5 in the opening or closing direction. - When the detected superheat degree is close to the set superheat degree, that is, when it is necessary to perform minute opening control in the electric expansion valve 5, the opening/closing control means 19 closes the electric expansion valve 5 to 1. It is driven alternately in the open direction and the close direction by steps. Then, in the electric expansion valve 5, an intermediate opening change corresponding to one step will occur, which makes it possible to perform minute changes in opening, that is, minute superheat degree control. .

(Example) Next, a specific example of the drive control device for an electric expansion valve according to the present invention will be described in detail with reference to the drawings.

In FIG. 1, 1 indicates an outdoor heat exchanger, and 2 indicates an indoor heat exchanger, and both 1.2 are connected in parallel by a liquid pipe 3 and a gas pipe 4.

An electric expansion valve 5 is provided in the liquid pipe 3, and a four-way switching valve 6 is provided in the gas pipe 4, and a compressor 7 is connected to the four-way switching valve 6.

In this case, the outdoor heat exchanger 1 serves as a condenser during cooling operation and an evaporator during heating operation, while the indoor heat exchanger 2 serves as an evaporator during cooling operation,
This part functions as a condenser during heating operation. A pair of temperature sensors 8.9 are attached to the liquid pipe 3 for detecting the refrigerant temperature on the evaporator inlet side, and a temperature sensor 10 is also attached to the pipe on the suction side of the compressor 7. It is attached. On the other hand, reference numeral 11 indicates the entire drive control device for the electric expansion valve, and this device 11 is based on the detection results of the temperature sensor 8 or 9 on the evaporator inlet side and the temperature sensor 10 on the compressor suction side. It has a superheat degree detection circuit 12 for detecting the degree of superheat at the sensor 8.
9.10 constitutes the superheat degree detection means 13. Note that 14 is an initial setting circuit for setting the opening degree of the electric expansion valve 5 at the start of operation. The respective outputs of the superheat degree detection circuit 12 and the initial setting circuit 14 are transmitted to the control circuit 1.
5, this control circuit 15 includes a determining means 16 for determining whether the degree of superheat detected by the detecting means 13 is close to the set degree of superheat, and other control functions 17. It has the following. If the detected degree of superheat is far from the set degree of superheat, the step control means 18 outputs a number of pulses to the electric expansion valve 5 according to the difference between the set degree of superheat and the detected degree of superheat. On the other hand, when the detected degree of superheat is close to the set degree of superheat, the opening/closing control means 19 applies one pulse in the valve opening direction and one pulse in the valve closing direction to the electric expansion valve 5. Each step is output alternately. The details of this control will be explained below.

FIG. 2 shows a first embodiment. First, the above initial setting circuit 1
4 to set the initial relationship of the electric expansion valve 5, and (
Step S1), drive compression t87 (Step S2
). Thereafter, in step S3, when a predetermined period of time has elapsed, the degree of superheat detected by the degree of superheat detecting means 13 is read out (step S4). And next step S
In step 5, it is determined whether the detected degree of superheat is within a reference preset degree of superheat range, smaller than that, or greater than that. In this case, if the detected degree of superheat is within the set range, the process returns to step S3 and repeats this operation. Further, if the detected superheat degree is smaller than the set superheat degree range, step S
6, a pulse is output to the electric expansion valve 5 in the valve closing direction. In this case, step control is performed in which a number of pulses corresponding to, for example, proportional to, the difference between the detected degree of superheat and the set degree of superheat are output to the electric expansion valve 5. After this, this state is maintained for a predetermined time (step S7),
Read out the detected superheat degree again (step S8),
In step S9, it is compared with a set superheat degree range. If the detected superheat degree is still smaller than the set superheat degree range, the process returns to step S6 and further valve closing operation is performed.
If the detected degree of superheat is within the set degree of superheat, the process returns to step S7 to maintain that state. When the detected superheat degree exceeds the set superheat degree range, the process moves to the following step S10 and shifts to the opening/closing control mode. If the detected degree of superheat exceeds the set superheat degree range in step S5, the reverse valve opening operation to the above is performed in steps Sll to S14, and the detected degree of superheat exceeds the set superheat degree range in step S14. When the size becomes smaller, the process moves to the opening/closing control mode in step S10.

In the opening/closing control mode, first, in step S15, a triangular wave voltage serving as a reference value for the degree of superheating is output.

As shown in Fig. 3(a), this triangular wave voltage is centered around the set superheat degree range and changes over time over a wider voltage range, and the width of the change is It is preferable to set the voltage to a value corresponding to the amount of change in the degree of superheat that occurs when the expansion valve 5 is changed by one step. On the other hand, along with the output of the triangular wave voltage, the detected superheat degree is output as a voltage in step 516, and then in step S17, the triangular wave voltage and the superheat degree voltage are compared. As a result, Figure 3 (al
When the two voltages do not overlap and the detected superheat degrees A and B are shifted up and down as shown in A and B shown in Fig. 3, it is determined that a change in the load or a change in the operation mode is likely, and step 318
At this point, this mode is stopped and the process returns to step S4. In addition, if the two voltages overlap as shown in the CSD in Figure 3 (al) and the detected superheat degree C is on the smaller side,
In step 319, a valve closing output is performed in the opening/closing control mode. That is, as shown in C of FIG. 3(b), the pulse motor of the electric expansion valve 5 is closed by one step from the current position within the sampling time, and opened by one step after 1/2 of the sampling time has elapsed. In other words, it performs an operation that causes it to return to its original position. By performing such an operation, the electric expansion valve 5 can obtain an opening equivalent to closing the valve by 1/2 step. Note that the opening/closing time ratio within the sampling time may be changed according to the deviation.

If the detected superheat degree voltage and the triangular wave voltage overlap and the detected superheat degree is on the larger side, a valve opening output in the opening/closing control mode is performed in step S20. In this case, contrary to the above valve closing output, within the sampling time,
The pulse motor of the electric expansion valve 5 is opened by one step from the current position, and after 1/2 of the sampling time has elapsed, the pulse motor is opened by one step from the current position.
It performs an operation that closes the valve by the amount of steps (
D) in Figure 3). As a result, in the electric expansion valve 5, an opening degree equivalent to opening the valve by 1/2 step is obtained. Note that the comparison of the triangular wave voltage and the superheat degree voltage in step s17 and the execution of each subsequent step are performed at each sampling time.

As described above, in the drive control device, when the detected degree of superheat is far from the set degree of superheat range,
In other words, if the detected degree of superheat does not overlap with the triangular wave voltage as shown in Fig. 3 (upper and lower positions A and H of al), the number of pulses corresponding to the difference between the set superheat degree range and the detected superheat degree is applied to the motor. Step control is performed to output the output to the expansion valve 5, and when the detected superheat degree is close to the set superheat degree range, that is, the superheat degree voltage and triangular wave voltage are If they overlap, the electric expansion valve 5 is driven alternately in the opening direction and the closing direction by one step within the sampling time. For this reason, in the above device, even if the electric expansion valve uses a pulse motor with a large step angle, the opening can be controlled to an apparent intermediate position of the step, which is equivalent to the high resolution of a pulse motor. As a result, it becomes possible to perform highly accurate superheat degree control.

FIG. 4 shows an example of a change in the control method. This is similar to the above, switching between the step control mode and the opening/closing control mode, but in this case, the procedure for determining whether or not to execute the opening/closing control mode is changed. First, the detected degree of superheat and the set degree of superheat are compared with the set superheat degree range using steps 31 to S5 that are exactly the same as in the above embodiment.

As a result, if the detected superheat degree is within the set range, the process returns to step S3 and the same procedure is repeated, and if the detected superheat degree is smaller than the set superheat range, then in step S6 A number of pulses corresponding to the deviation in the degree of superheat are output to the electric expansion valve 5 to operate the electric expansion valve 5 in the valve closing direction. If the detected degree of superheat exceeds the set superheat degree range, in step S7, a number of pulses corresponding to the deviation of the degree of superheat at that time are output to the electric expansion valve 5 to operate the electric expansion valve 5 in the valve opening direction. let Note that the steps after step S6 and the steps after step S7 are based on substantially the same idea, so below, only step S6 will be described.
Only the subsequent steps will be explained. When a pulse in the valve closing direction is output in the above step S6, the number of output steps at that time is counted in the next step S8. If the number of output steps is 2 or more, this state is held for a predetermined time (step s9>), then the degree of superheat is detected again (step 510), step S
The detected superheat degree and the set superheat degree range are compared at ll. As a result, if the detected degree of superheat is within the above range, step S9
Return to and repeat the same operation. If the detected degree of superheat is smaller than the set degree of superheat, the process returns to step S6 and the valve closing operation is repeated, and if the detected degree of superheat exceeds the set degree of superheat, the process proceeds to step S7 to open the valve. operation will be performed.

If the counted step number is 1 in step S8, it is held for a predetermined time in step S12, and then the degree of superheat is detected in step S13, and then the detected degree of superheat is detected in step S514. Compare with the set superheat degree range.

As a result, if the detected degree of superheat is within the set range, the process returns to step S12 to maintain this state, and if the detected degree of superheat is still smaller than the set degree of superheat, step S6
Return to and repeat the valve closing operation. On the other hand, if the detected degree of superheat exceeds the set degree of superheat in step S14, the degree of superheat detected in step 513 is stored in step S15. Next, in step 816, contrary to the above, a pulse in the direction of opening the electric expansion valve 5 by one step is outputted to open the electric expansion valve 5 by one step, and the electric expansion valve 5 is opened by one step. The temperature is maintained for a predetermined time in S17, and then the degree of superheat is detected again in step 318. And step S1
9, the degree of superheat detected above and the degree of superheat stored in step S15 are compared, and if they are the same or the degree of superheat detected later is greater, the load change is determined. It is determined that there has been a change in the operation mode, etc., and the process returns to the initial control, that is, step S5.

On the other hand, if the degree of superheat detected in step 318 is small, the detected degree of superheat is further compared with a set superheat degree range in step 520. As a result, if the detected superheat degree is within the set range, the process returns to step S3 and this opening degree is maintained, and if the detected superheat degree still exceeds the set superheat range, the first control ( Return to step S5). If the detected superheat degree is smaller than the set superheat degree range, the process moves to step 521 shown in FIG.
Performs valve closing output in opening/closing control mode.

The phenomenon of change in the degree of superheating from step S12 to step S20 will be explained based on FIG. In step S14, the set superheat degree is exceeded (point E of 61st m1a). And from this state 1
When the valve is opened by the number of steps (step 316), the superheat degree decreases (step S19), and further decreases beyond the set superheat degree range (step 520).
(Point F in Fig. 6 (al)) In other words, when the valve is opened for one step, the degree of superheating exceeds the set superheat degree range and becomes small (point F), and on the other hand, when the valve is opened for one step, When the valve is closed, the superheat degree exceeds the set superheat degree range (point G).

When such a state is reached, a valve closing output is performed in step S21 in FIG. 5. That is, as shown in the lower part of FIG. 6(b), the electric expansion valve 5
The electric expansion valve 5 is operated for a predetermined period of time to close the pulse motor by one step from the current position and open it by one step after 1/2 of the sampling time has elapsed, that is, to return to the original position. Only (step 522) is performed.

After this time has elapsed, the degree of superheat is read out again in step S23, and then this detected degree of superheat is read out in step S2.
Compare with the set superheat degree range in 4. As a result, if the detected degree of superheat is within the set range, step S21
If it is outside the setting range, the opening/closing control mode is stopped at step 525, and the process returns to the initial control, that is, step S5, to repeat the above-described series of operations. Repeat.

Even when the above-mentioned control is performed, as in the embodiment described above, even if the electric expansion valve 5 has a relatively large step angle, the opening degree can be controlled to an apparent intermediate position of the step. Therefore, it becomes possible to obtain a result equivalent to that obtained by increasing the resolution of a pulse motor, and it becomes possible to perform highly accurate superheat degree control.

(Effects of the Invention) The electric expansion valve drive control device of the present invention is provided with the step control means and the opening/closing control means as described above, and when it is necessary to perform minute opening control in the electric expansion valve, Since the opening/closing control means is designed to obtain an intermediate opening change corresponding to one step,
Even with an electric expansion valve using a motor with a relatively large step angle, it is possible to perform highly accurate superheat degree control. Further, when it is necessary to perform large opening degree control, it is possible to greatly change the opening degree using the step control means, so that it is possible to quickly cope with large superheat degree fluctuations.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a schematic configuration of the drive control device for an electric expansion valve according to the present invention together with a refrigerant circuit, FIG. 2 is a flowchart of an example of an operation control method in the device, and FIG.
a) is an explanatory diagram for explaining the relative positional relationship between the triangular wave voltage and the detected superheat degree voltage; FIG. Fig. 5 is a flowchart of a modification of the operation control method in the above device, Fig. 6 fa) is an explanatory diagram showing the state of change in the detected superheat degree due to the above operation, and Fig. 6 (bl shows the input state to the pulse motor). It is an explanatory diagram. 5... Electric expansion valve, 8.9.10... Temperature sensor number,
11... Drive control device, 12... Superheat degree detection circuit,
16... Discrimination means, 18... Step control means, 1
9... Opening/closing control means.

Claims (1)

[Claims] 1. superheat degree detection means (13) for detecting the degree of superheat of the evaporated refrigerant; and determination means (16) for determining whether or not the superheat degree detected above is close to the set superheat degree.
), and a step of outputting a number of pulses corresponding to the difference between the set superheat degree and the detected superheat degree to the electric expansion valve (5) when the detected superheat degree is far from the set superheat degree. a control means (18); and when the detected degree of superheat is close to the set degree of superheat, the electric expansion valve (5) is driven alternately in the opening direction and the closing direction by one step within the required time. 1. A drive control device for an electric expansion valve, comprising an opening/closing control means (19).