JP2000065348A - Proportional valve control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent occurrences of erroneous operation even when a small proportional valve is used, by stopping the operation of a closing means in the case where the calculated opening of a proportional valve is not less than a first given opening which is near the maximum opening. SOLUTION: When an operational switch 51 of an electric rice cooker is turned on, a control unit 5 determines an opening of a proportional valve 1 on the basis of the various kinds of parameters such as a detected temperature or the like from a temperature sensor 52 for detecting temperature of an inner pot. At this moment, a comparison is made between a current value corresponding to the opening which has been calculated by the control unit 5 and a current value obtained from an actually detected voltage value which has been inputted to an A/D terminal of the control unit 5. If the difference between the two values is not less than a first given opening which is near the maximum opening, either one is determined to be in failure and safety valves 12, 13 are closed, thereby cutting off gas which is supplied to a gas burner through a gas supply tube 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a proportional valve control device for controlling an opening of a proportional valve provided in a gas supply pipe for supplying gas to a gas burner, for example.

[0002]

2. Description of the Related Art As a conventional device of this type, for example, Japanese Patent Application Laid-Open No. 5-296452 discloses an opening control for calculating the opening of a proportional valve and controlling the operating current value of the proportional valve based on the calculation result. And an operating current to the proportional valve when an actual operating current value flowing through the proportional valve is detected and a difference between the opening corresponding to the detected operating current value and the calculated opening is equal to or greater than a predetermined value. There is known a proportional valve control device in which the supply of air is stopped and the proportional valve is closed. A maximum rated current value is set for the proportional valve, and an operating current value controlled by the proportional valve control device is set so as not to exceed the maximum rated current value. Therefore, when the calculated opening degree becomes the maximum and the operating current value becomes the maximum value, a threshold value is set between the maximum value of the operating current and the maximum rated current value, and the detected operating current value becomes When the threshold value is exceeded, the supply of the operating current to the proportional valve is stopped, and the proportional valve is closed.

[0003]

In the above-described conventional proportional valve control apparatus, in order to prevent an erroneous operation in which the proportional valve is forcibly closed even though no abnormality has occurred, it is necessary to operate the proportional valve. The difference between the maximum value of the current and the threshold value must be more than a certain value. Therefore, a proportional valve whose maximum rated current value is considerably larger than the maximum value of the operating current must be used. However, a proportional valve having a large maximum rated current value has a large shape, and there is a problem that the size of a device incorporating the proportional valve cannot be reduced. Also, the proportional valve becomes expensive as the maximum rated current value increases. Therefore, it is desirable to use a proportional valve having the smallest maximum rated current value as much as possible. However, if the maximum rated current value is reduced, the maximum value of the operating current is close to the threshold value, which may cause malfunction as described above.

In view of the above problems, an object of the present invention is to provide a proportional valve control device which does not cause a malfunction even if a proportional valve having a small maximum rated current value is used.

[0005]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention calculates an opening of a proportional valve and controls an operating current value of the proportional valve based on the calculation result. Detecting the actual operating current value flowing through the proportional valve and supplying the operating current to the proportional valve when the difference between the opening corresponding to the detected operating current and the calculated opening is equal to or greater than a predetermined value. In a proportional valve control device having a closing means for stopping, the operation of the closing means is stopped when the calculated opening degree is equal to or more than a first predetermined opening degree close to the maximum opening degree.

Generally, the time during which the calculation result of the opening degree of the proportional valve continuously exceeds the first predetermined opening degree is short. for that reason,
Even if the operation of the closing means is stopped when the calculated opening is equal to or more than the first predetermined opening, the calculated opening immediately becomes equal to or less than the first predetermined opening, and the stop for the closing means is released. You. Then, if a failure has occurred, the closing means is immediately activated to close the pipeline.

By the way, even when the opening corresponding to the detected operating current is smaller than the calculated opening, the closing means is operated to close the pipeline, but the calculated opening is close to the minimum opening. When the opening degree becomes equal to or less than the predetermined opening degree of 2, the operating current value itself becomes small, so that it becomes difficult to set a threshold value between the operating current value and the current value 0. On the other hand, the state where the calculated opening degree is equal to or less than the second predetermined opening degree does not last long. Therefore, when the calculated opening is equal to or less than the second predetermined opening, the operation of the closing means is stopped, and when the calculated opening becomes equal to or more than the second predetermined opening, a failure occurs. If this is the case, the stopping means may be activated to close the pipeline.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, reference numeral 1 denotes a proportional valve provided in a gas supply pipe 11 of a gas cooker. The gas supply pipe 11 has safety valves 12 and 13 composed of electromagnetic on-off valves.
Is provided upstream of the proportional valve 1. In the present embodiment, two safety valves 12 and 13 are provided, but only one of them may be provided. The opening of the proportional valve 1 is controlled by a solenoid coil 2 built in the proportional valve 1.
Is proportional to the value of the current flowing through. The solenoid coil 2 is connected in series with a transistor 31 constituting a constant current circuit 3 and a voltage dividing resistor 4 for current detection, and is connected to VCC which is a power supply. On the other hand, 5 is a control device for the rice cooker, which is constituted by a microcomputer. Temperature sensor 5 for detecting the temperature of the inner pot when the operation switch 51 of the rice cooker is turned on.
The control device 5 determines the opening degree of the proportional valve 1 based on various parameters such as the detected temperature from the control valve 2. Then, a pulse signal subjected to duty control so that a current corresponding to the determined opening degree flows through the solenoid coil 2 of the proportional valve 1 is output from the PWM terminal. The pulse signal output from the PWM terminal is converted by the smoothing circuit 6 into a DC signal having a voltage corresponding to the duty ratio. The constant current circuit 3 supplies a current corresponding to the voltage of the DC signal obtained by the smoothing circuit 6 to the solenoid coil 2.
The degree of opening of the transistor 31 is adjusted so that the current flows through the transistor 31.
Further, the current value actually flowing through the solenoid coil 2 is converted into a voltage value by the voltage dividing resistor 4 and input to the A / D terminal of the control device 5. In the control device 5, a current value corresponding to the calculated opening degree is compared with a current value obtained from a voltage value actually detected and input to the A / D terminal. When it was determined that a crab failure had occurred, the safety valves 12 and 13 were closed to shut off the gas supplied to the gas burner via the gas supply pipe 11. In this case, a notification means such as a buzzer may be operated.

This will be described in more detail with reference to FIG. 2. A table diagram shown in FIG. 2 is stored in the control device 5 in advance, and a current value flowing through the solenoid coil 2 is stored using the table diagram. Is calculated. For example, if the opening of the proportional valve 1 at that time is calculated as R from the elapsed time from the start of rice cooking, the temperature detected by the temperature sensor 52, and the like, the solenoid coil 2 of the proportional valve 1 The current value IR to be passed is calculated. Then, as described above, a pulse signal subjected to duty control so that the current flowing through the solenoid coil 2 becomes IR is output from the PWM terminal. On the other hand, the current value actually flowing through the solenoid coil 2 is obtained from the potential of the voltage dividing resistor 4, and the actual current value is compared with the current value IR obtained by the above calculation. An error upper limit UL and an error lower limit LL are set on the table line T. When the opening is R, the current value actually flowing through the solenoid coil 2 is equal to the upper limit value IRU which is a threshold value around IR. It suffices if it is between the lower limit value IRL and the threshold value. If the detected actual current value does not fall between the upper limit value IRU and the lower limit value IRL, it is determined that an error has occurred as described above, and the safety valves 12 and 13 are closed.

In the present invention, the calculated proportional valve 1 is used.
When the opening degree is equal to or more than the first predetermined opening degree of 80% and the second opening degree.
The calculated current value is not compared with the detected actual current value when the predetermined opening degree is 20% or less. That is, the current value I calculated when the opening is 100%
100 is 170 mA, and the maximum rated current value Imax of the solenoid coil 2 is 200 mA.
max is close to the upper limit, and an upper limit value, which is a threshold value, cannot be set between the two. Therefore, when the calculated current value becomes about 140 mA and the opening degree becomes 80% or more, the calculated current value is not compared with the detected actual current value. Note that the calculated opening becomes 80% or more during about several tens of seconds during rice cooking, and even if the calculated opening becomes 80% or more, the calculated opening immediately becomes 80% or less. . Then, the calculated current value is compared with the detected actual current value again. If the actual current value does not fall between the error upper limit UL and the error lower limit LL, the safety valves 12 and 13 are closed. So there is no problem. Also, when the opening degree becomes 20% or less, the error lower limit LL becomes 0.
mA or less. Since the current value does not fall below 0 mA, it is not possible to set the lower error limit LL, which is the lower threshold. Therefore, the opening degree 20% corresponding to a current value of about 50 mA
Hereinafter, the calculated current value is not compared with the detected actual current value. It should be noted that the opening calculated during the cooking of rice is less than 20% only for about several tens of seconds, so that when the calculated opening returns to 20% or more, the current value calculated and the actual value detected are detected. The current values are compared with each other. If the actual current value does not fall between the error upper limit UL and the error lower limit LL, there is no problem because the safety valves 12 and 13 are closed.
OS is an offset value set for each proportional valve.

In the above embodiment, when the calculated opening is 80% or more or 20% or less, the calculated current value is not compared with the detected actual current value. The safety valves 12 and 13 should not be closed even if the comparison is not performed. Further, in the above embodiment, the case where the present invention is applied to a gas cooker has been described. However, the present invention can be applied to any apparatus using a proportional valve such as a gas water heater.

[0012]

As is apparent from the above description, according to the present invention, even if a proportional valve having a small maximum rated current value is used,
It is possible to prevent an erroneous operation in which the supply of gas is forcibly stopped even though no failure has occurred.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a calculated opening degree and a current value to be supplied to a proportional valve;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Proportional valve 2 Solenoid coil 4 Voltage division resistance 5 Controller 11 Gas supply pipe 31 Transistor

Claims (2)

[Claims] 1. An opening control unit for calculating an opening of a proportional valve provided in a pipeline, and controlling an operating current value of the proportional valve based on the calculation result, and an actual operating current flowing through the proportional valve. A proportional valve control device having a closing means for closing the pipeline when the difference between the opening degree corresponding to the detected operating current value and the calculated opening degree is greater than or equal to a predetermined value. When the calculated opening is equal to or greater than a first predetermined opening close to the maximum opening, the operation of the closing means is stopped. 2. The proportional valve control device according to claim 1, wherein the operation of the closing means is stopped when the calculated opening is equal to or less than a second predetermined opening close to the minimum opening. .