JPH10252922A - Positioner for valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the heat from being applied to a member for mounting, and avoid the defective operation and degradation or damages of the equipment by providing a temperature judging means to detect the temperature in a casing, and judge whether or not the detected temperature is in the prescribed range of the set temperature. SOLUTION: A positioner for valve is provided with a temperature detecting means 10 to detect the temperature in a casing, such as a temperature sensor, and a temperature judging circuit 11 (a temperature judging means) to judge whether or not the detected temperature is in the prescribed range of the set temperature. When the detected temperature by the temperature detecting means 11 is judged not to be in the prescribed range of the set temperature by the temperature judging circuit 11, the output command to be transmitted to an electric actuator from a control means 8 is switched to the predetermined set output command. A non-volatile memory 12 in which the history of the temperature detected by the temperature detecting means 11 is stored, is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positioner for a valve, and more particularly, to an abnormal operation and damage of a relatively low heat-resistant electronic component which is covered in a substantially sealed shape by a main casing. The present invention relates to a valve positioner.

[0002]

2. Description of the Related Art For the purpose of controlling the flow rate of a low-pressure fluid having a large flow rate, for example, a butterfly valve having excellent control resolution is often used as a valve. FIG. 2 shows an electric actuator (E.C.) for driving and controlling the butterfly valve.
FIG. 3A is a diagram showing a schematic configuration of a valve positioner incorporated therein, and FIG. 3 is a block diagram showing a functional configuration of the valve positioner.

As shown in FIG. 2, the electric actuator C0 includes a motor 2 for driving a valve shaft 1 of a butterfly valve (not shown) and a forward / reverse rotatable motor 2 and an operation of the electric actuator C0. It comprises a control means CG for controlling the angle, and a mounting member 3 such as a substrate on which the valve positioner CP is mounted.
More specifically, the valve positioner CP is shown in FIG.
As shown in FIG. 3, an angle detecting means 4 such as a potentiometer for detecting the operation angle of the electric actuator C0.
An A / D converter 5 for digitizing the operation angle of the electric actuator C0 detected by the angle detection means 4, a set value input circuit 6 for inputting a set value of a predetermined operation angle, An A / D converter 7 for digitizing the output of the set value input circuit 6 and a motor 2 built in the electric actuator C0, for example, based on the digitized operation angle and set value of the electric actuator C0. A control circuit 8 comprising digital operation means for transmitting an output command; and a motor drive circuit 9 for driving the motor 2 based on the output command transmitted from the control circuit 8.
Control drive.

In the above valve positioner CP,
When a set value is input to the set value input circuit 6 and the flow control by the butterfly valve is started, the operating angle of the electric actuator C0 is monitored by the angle detecting means 4. In the control circuit 8, for example, PI control is performed based on a deviation between the operation angle of the electric actuator C0 digitized by the A / D converter 5 and the set value, and an output command to the motor 2 is generated. Is done. Then, electric power corresponding to the output command is supplied to the motor 2 by the motor drive circuit 9. Then, the valve shaft is rotated by the torque of the motor 2, and the flow rate is controlled by the butterfly valve.

[0005]

In the electric actuator C0 as described above, the electronic components such as the valve positioner CP are protected, and the valve positioner CP and the like are used in order to improve the appearance of the device. Covered by casing C. However, when the actuator C0 is used frequently, the ambient temperature in the casing C rises due to heat generated by the motor 2 or the like depending on the installation environment, and exceeds the heat-resistant temperature of the control circuit 8 or other electronic components. There is a risk that it will. Here, FIG. 4 is a diagram showing the motor ambient temperature, the on-board temperature, and the environmental temperature in time series.

As shown in FIG. 4, when the ambient temperature is about 30.degree. C., the ambient temperature of the electric actuator during driving exceeds 90.degree.
The temperature on the substrate inside has risen to near 50 ° C.
Therefore, if such a high-temperature state continues for a long time without being detected by the user, etc., it may cause malfunction of the control circuit and deterioration and damage of the electronic components, which may reduce the operational reliability of the actuator and the valve positioner. Becomes SUMMARY OF THE INVENTION In order to solve the problems in the prior art, the present invention has improved a valve positioner and provided with a temperature determining means for determining whether or not the temperature in a casing is within a set temperature. It is an object of the present invention to provide a valve positioner that can detect the above at an early stage and avoid the above-mentioned adverse effects.

[0007]

In order to achieve the above object, the present invention provides control means for controlling a forward / reverse rotatable electric actuator for driving a valve, and a mounting member on which the control means is mounted. In a valve positioner provided with the control means and the mounting member being substantially hermetically covered by a casing, a temperature detecting means for detecting a temperature in the casing and a temperature detected by the temperature detecting means are provided. A temperature determining means for determining whether the temperature is within a predetermined set temperature is provided as a valve positioner. In the valve positioner, it is possible to determine that the temperature in the casing has risen by the temperature determination means. Based on the determination, the surrounding heat source is stopped or the like, and the control means and the control means are controlled. Heat is prevented from being applied to the mounting member on which the control means is mounted for a long time, and as a result, malfunction of the control means and deterioration and damage of equipment can be avoided.

In the valve positioner, for example, when the temperature detected by the temperature detecting means is determined not to be within the predetermined set temperature by the determining means, the control means sends the temperature to the electric actuator. If the output command is switched to a predetermined set output command, the drive of the electric actuator, which is one of the heat sources, is stopped or reduced in frequency, so that the temperature rise in the casing can be reduced.

In the valve positioner, an output means for notifying to the outside that the temperature detected by the temperature determining means is not within the predetermined set temperature is determined by the determining means. If it is provided, for example, it is possible to use the signal from the output means to notify the operator or other control devices and take emergency measures. By the way, the valve positioner is effective especially when the control means is formed of an electronic component having relatively low heat resistance, and a decrease in reliability of the valve positioner due to a malfunction of a semiconductor or the like is reduced. Further, if a storage means for holding a history of the temperature detected by the temperature detection means is provided, the temperature history in the casing at the time of the butterfly valve drive control is obtained.
The user can easily grasp the operating environment and determine a response to the temperature abnormality.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention.
The following embodiments show specific examples of the present invention, and do not limit the technical scope of the present invention. FIG. 1 is a block diagram showing a functional configuration of a valve positioner according to one embodiment of the present invention. As shown in FIG. 1, the valve positioner 0 includes an angle detecting means 4 such as a potentiometer for detecting an operating angle of the electric actuator C0, and an operating angle of the electric actuator C0 detected by the angle detecting means 4. A / D converter 5 for digitizing the data
A set value input circuit 6 for inputting a set value of a predetermined operation angle, an A / D converter 7 for digitizing the output of the set value input circuit 6, and the digitized electric actuator C0. A control circuit 8 composed of, for example, digital operation means for transmitting an output command of the motor 2 built in the electric actuator C0 based on the operation angle and the set value of the electric actuator C0, and an output command transmitted from the control circuit 8 And a control circuit 8 (corresponding to control means) for controlling a forward / reverse rotatable motor for driving a valve (not shown) such as a butterfly valve, for example. The control circuit 8 includes a mounting member 3 such as a substrate on which the control circuit 8 is mounted, and the control circuit 8 and the mounting member 3 are substantially sealed by a casing C. Is the same as the come of technology.

On the other hand, the valve positioner 0 is different from the conventional one in that a temperature detecting means 10 for detecting the temperature in the casing C, such as a temperature sensor, and a temperature detected by the temperature detecting means 10 are provided. Temperature determination circuit 11 (corresponding to temperature determination means) for determining whether or not the temperature is within a predetermined set temperature, and the temperature determination circuit 11 determines that the temperature detected by the temperature detection means 11 is not within the predetermined set temperature. When a determination is made by the circuit, a setting output command switched from an output command sent from the control means to the electric actuator, a setting of a set temperature, and a history of the temperature detected by the temperature detecting means are retained. And a nonvolatile memory 12.

In the valve positioner 0, the settings such as the set temperature and the set output command are input to the nonvolatile memory 12 via an external communication device 13 such as a personal computer and a communication circuit 14 such as RS-232C. Will be retained. Here, in the valve positioner 0 according to the present embodiment, an EPROM or the like having good data storability is used for the non-volatile memory 12, so that the component configuration on the mounting member is simplified. The set value of the operation angle of the electric actuator is input to the set value input circuit 6 in advance, as in the conventional case. In the valve positioner 0, when the control by the butterfly valve is started, the operation angle of the electric actuator C0 is monitored by the angle detecting means 4. In the control circuit 8, the deviation between the operation angle of the electric actuator C0 digitized by the A / D converter 5 and the set value is, for example, P
The I control is performed, and an output command to the motor 2 is created. Then, electric power corresponding to the output command is supplied to the motor 2 by the motor drive circuit 9. Then, the flow rate is controlled by the butterfly valve driven by the motor 2.

If the temperature in the casing C rises because the motor 2 is frequently used, for example, the electronic components such as the control circuit 8 may malfunction or deteriorate, as described above. Therefore, the valve positioner 0 is monitored by the temperature detecting means 10 during use.

The temperature signal sent from the temperature detecting means 10 is digitized by an A / D converter 15 and input to a temperature determining circuit 11. The temperature determination circuit 11 stores the input temperature signal in the non-volatile memory 12 to create a temperature history, and sets the temperature stored in the non-volatile memory 12 and the temperature detected by the temperature detection means 10. If the detected temperature is higher than the set temperature, the temperature determination circuit 11 determines that the ambient temperature in the casing C has abnormally increased, and is sent from the control circuit 8 to the motor. The output command is switched to the setting output command stored in the nonvolatile memory 12. The setting output command has a content of, for example, stopping the motor 2 or reducing the operation frequency. On the other hand, when the temperature determination circuit 11 does not determine that the ambient temperature in the casing C has abnormally increased, the normal control by the control circuit 8 is continued.

As described above, in the valve positioner 0 according to the present embodiment, even if an abnormal temperature rise occurs in the casing C, the temperature rise is detected early and the amount of heat from the motor 2 and the like is reduced. In addition, malfunction of the control circuit 8 and deterioration and damage of components can be prevented. Further, since the temperature change in the casing C is stored in the non-volatile memory 12, the user can easily grasp the operating environment from the stored contents,
A response to the temperature rise can be determined.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the above embodiment, the temperature judgment circuit 11 has been described.
When it is determined that a temperature abnormality has occurred, the output command sent from the control circuit 8 to the motor 2 is switched to the set output command held in the nonvolatile memory 12.
An output unit 16 for notifying an abnormal temperature is provided outside, and a warning light is turned on by a signal output from the output unit 16 or a buzzer sounds to stop the control of the motor 2 by a user. Alternatively, the temperature may be lowered by a cooling device or the like. Here, the output means 1
For example, a relay contact may be used for 6, or a digital signal or the like may be output. Further, the switching of the output command as described above and the notification to the outside by the output means 16 may be simultaneously performed. In this case, the temperature rise in the casing C can be suppressed at an early stage, and it is not necessary for the user to constantly monitor the temperature, so that the burden on the user can be reduced. Such a valve positioner is also an example of the valve positioner in the present invention.

[0017]

As described above, the present invention comprises control means for controlling a forward / reverse rotatable electric actuator for driving a valve, and a mounting member on which the control means is mounted.
In a valve positioner in which the control means and the mounting member are substantially sealed by a casing,
Temperature detecting means for detecting the temperature in the casing; and temperature determining means for determining whether or not the temperature detected by the temperature detecting means is within a predetermined set temperature. It is configured as a valve positioner. In the valve positioner, it is possible to determine that the temperature in the casing has risen by the temperature determination means. Based on the determination, the surrounding heat source is stopped or the like, and the control means and the control means are controlled. Heat is prevented from being applied to the mounting member on which the control means is mounted for a long time, and as a result, malfunction of the control means and deterioration and damage of equipment can be avoided.

In the valve positioner, for example, when the temperature detected by the temperature detecting means is determined not to be within the predetermined set temperature by the determining means, the control means sends the temperature to the electric actuator. If the output command is switched to a predetermined set output command, the drive of the electric actuator, which is one of the heat sources, is stopped or reduced in frequency, so that the temperature rise in the casing can be reduced.

In the valve positioner, an output means for notifying to the outside that the temperature detected by the temperature determining means is not within the predetermined set temperature is determined by the determining means. If it is provided, for example, it is possible to use the signal from the output means to notify the operator or other control devices and take emergency measures. By the way, the valve positioner is effective especially when the control means is formed of an electronic component having relatively low heat resistance, and a decrease in reliability of the valve positioner due to a malfunction of a semiconductor or the like is reduced.

Further, if a storage means for holding a history of the temperature detected by the temperature detecting means is provided, the user can easily read the temperature history in the casing at the time of the butterfly valve drive control. It is possible to grasp the operating environment and determine the response to the temperature abnormality.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a valve positioner 0 according to an embodiment of the present invention.

FIG. 2 is a diagram showing a schematic configuration of an electric actuator C0 that drives a butterfly valve.

FIG. 3 is a diagram showing a schematic configuration of a conventional valve positioner CP.

FIG. 4 is a view for explaining a temperature state in a casing C;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Valve shaft 2 ... Motor with built-in electric actuator 3 ... Mounting member 4 ... Angle detection means 6 ... Set value input circuit 8 ... Control circuit 9 ... Motor drive circuit 10 ... Temperature detection means 11 ... Temperature determination circuit 16 ... Output means C0: Electric actuator

Claims (5)

[Claims] A control means for controlling a forward / reverse rotatable electric actuator for driving a valve, and a mounting member on which the control means is mounted, wherein the control means and the mounting member are substantially sealed by a casing. A temperature detecting means for detecting the temperature in the casing, and determining whether or not the temperature detected by the temperature detecting means is within a predetermined set temperature. A valve positioner comprising: a temperature determining unit. 2. An output command sent from the control means to the electric actuator when the temperature detection means determines that the temperature detected by the temperature detection means is not within the predetermined set temperature. 2. The valve positioner according to claim 1, wherein the position is switched to a predetermined set output command. 3. An output means for notifying to the outside that a determination has been made by said determination means that the temperature detected by said temperature determination means is not within the predetermined set temperature. 3. The positioner for a valve according to 1 or 2. 4. The valve positioner according to claim 1, wherein said control means comprises an electronic component having relatively low heat resistance. 5. The valve positioner according to claim 1, further comprising storage means for holding a history of the temperature detected by said temperature detection means.