JP2000337551A - Electric actuator for driving valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely eliminate a dewing in a casing receiving electrical equipment and to prevent a trouble or malfunction in the electrical equipment by detecting the humidity in the casing by a humidity detecting means, and controlling the current to be supplied to a heater base on the detected humidity. SOLUTION: The electric actuator 1 for driving valve is provided with a reversible electric motor 4 for driving the valve shaft 3 of a butterfly valve or the like, and a control base plate 5 on which an electrical equipment for controlling the electric motor 4 is mounted, within a casing 2. In this case, a humidity sensor is mounted on the control base plate 5 to detect humidity in the casing 2. A humidity signal detected by the humidity sensor is supplied to a humidity monitor function circuit through an A/D converter, hereat the detected humidity is compared with set humidity held in non-volatile memory, and in the case of the detected humidity over the set humidity, a current is carried to a heater 6 provided on the control base plate 5 to raise temperature in the casing 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric actuator for driving a valve, and more particularly, to an electric motor for driving a valve such as a butterfly valve, an electric component for controlling the electric motor, and an electric motor. The present invention relates to a valve driving electric actuator in which a heating heater is housed at least in a casing.

[0002]

2. Description of the Related Art For example, in a pipe of a building air conditioner, a valve driving electric actuator used for driving a valve is often installed outdoors such as on the roof of a building. In this case, the valve driving electric actuator is exposed to wind and rain or direct sunlight. If the electric motor and various electric components included in the valve driving electric actuator get wet, a failure or a malfunction may occur. Therefore, the electric motor and various electric components are usually housed in a casing. However, condensation may occur in the casing depending on the change in the outside air temperature. For example, when the electric actuator for driving a valve is installed on a cooling tower on a building roof, the outside air temperature in the vicinity of the electric actuator for driving a valve is 70 ° C. to 8 in the daytime on a hot summer day.
Although it may rise to about 0 ° C,
If the outside air temperature suddenly drops at night, there is a high possibility that dew condensation will occur in the casing. Even if the electric motor and the various electric components are protected from rainwater by the casing, if the electric motor and the various electric components continue to be condensed, a failure or a malfunction may still occur.
A technique aimed at preventing such dew condensation is described in, for example, JP-A-10-61809. According to the technique described in the above publication, a heater is disposed in a casing, and energization control of the heater is performed so as to maintain a temperature of an inner wall of the casing in a predetermined range.

[0003]

In the technique described in the above publication, dew condensation is prevented by maintaining the temperature of the inner wall of the casing within a predetermined range. If the humidity inside the casing changes more rapidly than the temperature, the temperature inside the casing may not rise sufficiently due to the control of the power supply to the heater, and the dew condensation may not be sufficiently prevented. In addition, if water enters the casing due to some external factor, and the temperature inside the casing rises in that state, the infiltrated water evaporates and the inside of the casing becomes a high-temperature and high-humidity state, so that dew condensation easily occurs. . Even in such a high-temperature and high-humidity state, it is difficult for the user to quickly grasp the situation because the technique described in the above publication cannot make a determination. In order to solve the problems in the prior art, the present invention improves an electric actuator for driving a valve, detects a humidity in a casing accommodating an electric motor and electric components, and detects a humidity based on the detected humidity. By performing dew condensation prevention measures such as controlling the heater energization to prevent dew condensation, even if water enters the casing due to external factors, this fact is automatically controlled. It is an object of the present invention to provide a valve-driving electric actuator that can determine the above and notify the user.

[0004]

In order to achieve the above object, an invention according to claim 1 includes an electric motor for driving a valve, an electric component for driving and controlling the electric motor,
In an electric actuator for driving a valve in which a heater for raising a temperature is housed at least in a casing, humidity detecting means for detecting humidity in the casing, and the heater based on the humidity in the casing detected by the humidity detecting means. And a dew-prevention processing means for controlling energization of the valve. According to a second aspect of the present invention, in the electric actuator for driving a valve according to the first aspect, the electric component includes an operating angle detecting means for detecting an operating angle of the electric motor, and the operating angle detecting means. A positioner including a control circuit for generating a control signal for the electric motor based on the detected operating angle of the electric motor, and a motor drive circuit for driving the electric motor based on the control signal generated by the control circuit Wherein the dew condensation preventing means stops the control circuit based on the operation angle of the electric motor, and sends a predetermined operation signal from the control circuit to the motor drive circuit. That the processing is further performed based on the humidity in the casing detected by the humidity detecting means. To. Also,
According to a third aspect of the present invention, in the electric actuator for driving a valve according to the first or second aspect, the dew-condensation preventing processing means is configured to control the inside of the casing based on the humidity in the casing detected by the humidity detecting means. The gist of the present invention is to further perform a process of notifying the humidity state to the outside. According to a fourth aspect of the present invention, in the electric actuator for driving a valve according to any one of the first to third aspects, the dew-condensation prevention processing means is activated for a predetermined time or more after the heater is turned on. The gist is that, if the humidity in the casing detected by the humidity detecting means does not fall below the set humidity even after the lapse of time, a process for notifying the outside that there is an abnormality in the casing is further performed. I do. The invention according to claim 5 is as follows.
5. The non-volatile memory according to claim 1, wherein the dew-prevention processing unit is capable of rewriting a history of humidity in the casing detected by the humidity detection unit. 6. It is the gist that it is created in

[0005] According to the electric actuator for driving a valve according to any one of claims 1 to 5, an electric motor,
Since the humidity in the casing in which the electric component for controlling the electric motor is accommodated is detected, and the energization control of the heater accommodated in the casing is performed based on the detected humidity in the casing, Even when the outside air temperature near the installation location of the valve driving electric actuator changes suddenly, it is possible to reliably prevent dew condensation from occurring in the casing. Further, according to the valve driving electric actuator of the second aspect, in addition to the control of the heater energization based on the humidity in the casing, the control based on the operation angle of the electric motor is stopped, and the predetermined operation signal is output. Since the process given to the motor drive circuit for driving the electric motor is performed, it is possible to prevent dangerous operation from being performed even if the electric motor or the electric component has a failure or malfunction due to dew condensation. According to the third aspect of the present invention, since the process of notifying the humidity state inside the casing to the outside is further performed, the user can quickly grasp the state inside the casing. . Further, according to the valve driving electric actuator according to the fourth aspect, even if a predetermined time or more has elapsed after the energization of the heater is started, if the humidity in the casing does not fall below the set humidity, Since it is notified to the outside that there is an abnormality in the casing, the user can quickly perform maintenance. According to the valve driving electric actuator of the fifth aspect, the history of the humidity in the casing is recorded in the rewritable nonvolatile memory, so that the user can easily take a countermeasure against dew condensation according to the installation environment. You can figure out.

[0006]

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 embodiment is a specific example of the present invention and does not limit the technical scope of the present invention. First, FIG. 1 is a diagram for explaining an overall schematic configuration of an electric actuator 1 for driving a valve according to an embodiment of the present invention. As shown in FIG. 1, an electric actuator 1 for driving a valve according to the present embodiment controls an electric motor 4 capable of rotating forward and reverse in a casing 2 for driving a valve shaft 3 such as a butterfly valve. And a control board 5 on which electrical components for performing the above operations are mounted. The casing 2 includes several detachable covers 21, and an attachment portion of each cover 21 is provided with an O-ring 22.
It has a waterproof structure sealed by using. A viewing window 23 made of a transparent resin is provided at a position corresponding to the uppermost portion of the casing 2. Immediately inside the sight glass 23 and at the top of the valve shaft 3, a dish-shaped member 31 is attached with a mark corresponding to the fully open or fully closed position of the valve. By checking the position of the marking through the viewing window 23, the approximate operating angle of the valve can be easily known. Below the dish-shaped member 31 of the valve shaft 3 is mounted a limit cam 32 having a groove in the circumferential direction corresponding to the operation angle from full opening to full closing of the valve. The limit rod 33 can be fixed to an arbitrary position of the above groove using a nut.
When the limit bar 33 contacts the limit switch 51 on the control board 5 and below the groove, it is possible to electrically detect whether the valve is fully open or fully closed. A lamp or the like is connected to the output side of the limit switch 51. When the valve is fully opened or closed, the lamp is turned on to notify the user of the fact.
Further, a gear is provided on the outer periphery of the limit cam 32, and a potentiometer 52 is arranged at a position where the gear meshes with the gear. When the limit cam 32 rotates, the resistance of the potentiometer (an example of the operation angle detecting means) 52 changes accordingly. The output of the potentiometer 52 can be directly output to the outside from the connection terminal of the terminal block 53 provided on the control board 5, but can also be supplied to a positioner disposed in the casing 2.

FIG. 2 shows a functional block diagram of the positioner. As shown in FIG.
00 denotes an operation angle feedback signal generator 201, a feedback input circuit 202, a set value input circuit 203,
A control unit including a determination circuit (corresponding to a control circuit) 204 and the like, and a motor drive circuit 205 for driving the electric motor 4 based on a command from the control unit are provided as basic components. For example, it is implemented. The operation angle feedback signal generator 201 in the control unit is, for example, the potentiometer 52, which detects the operation angle of the electric motor 4 and feeds back the detection signal. The detection signal from the operation angle feedback signal generator 201 is supplied to the feedback input circuit 202 and the A / D converter 20.
The signal is supplied to the determination circuit 204 via the control circuit 21. The set value input circuit 203 is a circuit for inputting a set value of a predetermined operation angle.
03 is also supplied to the determination circuit 204 via the A / D converter 2031. In the determination circuit 204, the P based on the deviation between the set value of the operation angle and the detection signal is determined.
I control and the like are performed, and a command signal is generated. The command signal is supplied to the motor drive circuit 205. The electric power corresponding to the command signal is supplied to the electric motor 4 by the motor drive circuit 205, and the operation angle of the electric motor 4 is controlled to a desired angle. The determination circuit 204 is realized by digital operation means such as a microcomputer, but the microcomputer and the A / D converter 202 are used.
1, 2031, a motor drive circuit 205, a limit switch 51, a potentiometer 52, and the like are examples of electrical components mounted on the control board 5 in the casing 2.

In the electric actuator 1 for driving a valve, as described above, the mounting portion of each cover 21 is provided with an O-ring 22 in order to prevent the electric components and the like from being exposed to rainwater.
Sealed using. Therefore, if there is no change in the seal, the amount of water vapor in the casing 2 is substantially constant. Therefore, the valve driving electric actuator 1
When the outside air temperature in the vicinity decreases rapidly, the casing 2
Condensation forms in the interior. If the dew condensation continues on the electrical components, a failure or malfunction may be caused. In the electric actuator 1 for driving a valve, the heater 6 is mounted on the control board 5. Prevention circuitry has been added. The circuit for preventing dew condensation includes a humidity sensor (an example of humidity detecting means) 20.
6. Humidity monitoring function circuit (corresponding to dew condensation preventing means) 20
7, a nonvolatile memory 208, a heater drive circuit 209, a humidity detection signal generation circuit 210, and a communication circuit 211. The humidity sensor 206 is mounted, for example, on the control board 5 and detects the humidity in the casing 2. A known sensor can be used as the humidity sensor 206. For example, in the humidity sensor shown in FIG. 3, a pair of comb-shaped electrodes are opposed to each other in a state where they are not in contact with each other, and a moisture-sensitive film using a polymer as a moisture-sensitive material is formed therebetween. If the moisture-sensitive film absorbs and desorbs moisture, the resistance changes, and an electrical signal corresponding to the humidity at that time is obtained. The humidity signal detected by the humidity sensor 206 is A / D
It is supplied to the humidity monitor function circuit 207 via the converter 2061. The humidity monitoring function circuit 207 stores the supplied humidity signal in the non-volatile memory 208 and creates a humidity history. By recording the history of the humidity in the non-volatile memory 208, the user can easily grasp a countermeasure according to the installation environment of the electric actuator 1 for driving the valve. The humidity monitoring function circuit 207
Compares the set humidity stored in the nonvolatile memory 208 with the humidity signal supplied from the humidity sensor 206, together with the recording of the humidity history in the nonvolatile memory 208. If the detected humidity is significantly lower than the set humidity, the humidity monitoring function circuit 207
It is determined that there is no risk of dew condensation, and a safety signal indicating that fact is supplied to the determination circuit 204. In the determination circuit 204, when the safety signal is supplied from the humidity monitoring function circuit 207, the operation angle of the electric motor 4 supplied from the A / D converter 2021 is processed as it is, and Drive circuit 205
Drives the electric motor 4. On the other hand, if the detected humidity is higher than the set humidity or the detected humidity is approaching the set humidity, it is determined that dew condensation may occur. Processing for ensuring safety in the event of a failure is performed. In the above processing, there is a user who energizes the heater 6 provided on the control board 5 to increase the temperature in the casing 2 or causes the electric motor 4 to perform a predetermined operation. The processing includes notifying the occurrence of dew condensation and the like to the outside.

For example, when the detected humidity is higher than the set humidity, there is a high possibility that dew condensation has occurred. In this case, the humidity monitoring function circuit 33 determines that dew condensation may occur, and the nonvolatile memory 20
8, a predetermined operation signal is read out, and
4 is supplied. The predetermined operation signal is, for example, a signal for driving the electric motor 4 to fully open or completely close the valve. Humidity monitoring function circuit 207
Is supplied from the A / D converter 2021, the determination circuit 204 does not perform the control corresponding to the operation angle of the electric motor 4 supplied from the A / D converter 2021. A corresponding command is output to the motor drive circuit 205. The predetermined operation signal can be rewritten by the user to the nonvolatile memory 208 according to the use environment from outside through the external communication device 212 and the communication circuit 211, for example. As the nonvolatile memory 208, for example, an EEPROM or a flash memory is used. The external communication device 212,
The communication circuit 211 in the casing 2 is connected by wire or wirelessly. Accordingly, even if a failure or malfunction occurs in the electrical components due to dew condensation, a safety operation selected by the user can be performed. Further, with the transmission of the predetermined operation signal, the humidity monitoring function circuit 207 is output.
Is supplied to the heater drive circuit 209. In the heater drive circuit 209, power is supplied to the heater 6 provided on the control board 5 in accordance with a power supply command supplied from the humidity monitoring function circuit 207.
This energization is performed, for example, until the detected humidity falls below the set humidity. As a result, the temperature inside the casing 2 rises and dew condensation is prevented. When the detected humidity is approaching the set humidity, the control of the electric motor 4 based on the operation angle is continued, and the energization control via the heater drive circuit 209 is performed. However, the above case of processing based on the detected humidity is an example.
In addition to the power supply control to the heater 6 based on the detected humidity, a user or the like may arbitrarily set. Further, when the detected humidity is extremely high, not only a command is given to the electric motor 4 and the heater 6 but also the user may be notified. In this case, the humidity monitoring function circuit 207 sends a command signal to the humidity detection signal generation circuit 210 to notify the humidity detection signal generation circuit 210 to the outside. The humidity detection signal generation circuit 210 is connected to an external contact provided on the casing 2, and the humidity at that time and a signal for giving a warning are supplied to the external terminal via the external contact. .

The valve driving electric actuator 1 prevents dew condensation and ensures safety in this way, but since the humidity in the casing 2 is directly detected by the humidity sensor 206, it is simply said that dew condensation has occurred. In addition to the determination, it is also possible to determine that water has entered the casing 2 due to some external factor. When the temperature inside the casing 2 rises after water enters the casing 2 due to an external factor, the inside of the casing 2 is in a high-temperature and high-humidity state, and dew condensation is extremely likely to occur. Therefore, if the humidity does not become lower than the set humidity for a predetermined time or more after the heater 6 is energized by a command of the humidity monitoring function circuit 207, the amount of water vapor initially contained in the casing 2 is reduced. If a large amount of water vapor is present in the casing 2, the humidity monitoring function circuit 207 makes a judgment, and the humidity detection signal generation circuit 2
Sends a command to 10 and informs it to the outside. As a result, even when a problem that cannot be dealt with only by the prevention of dew condensation occurs in the valve driving electric actuator 1, the user can quickly cope with the problem. As described above, according to the valve driving electric actuator of the present embodiment, the humidity in the casing accommodating the electric motor and the electrical components for driving and controlling the electric motor is detected, and the detected casing is detected. Because the energization control of the heater housed in the casing is performed based on the humidity in the inside,
Even when the outside air temperature near the installation location of the valve driving electric actuator changes suddenly, it is possible to reliably prevent dew condensation from occurring in the casing. Moreover, in addition to the control of energization of the heater based on the humidity in the casing, the control based on the operation angle of the electric motor is stopped, and a process of providing a predetermined operation signal to a motor drive circuit for driving the electric motor is performed. Even if the electric motor or the electric component has a failure or malfunction due to dew condensation, dangerous operation can be prevented from being performed. Furthermore, when the process of notifying the humidity state inside the casing to the outside is performed as necessary, the user can quickly grasp the state inside the casing. In addition, if the humidity in the casing does not fall below the set humidity even if a predetermined time or more has elapsed after the energization of the heater is started, it is notified to the outside that there is an abnormality in the casing.
The user can perform maintenance quickly.
Further, since the history of the humidity in the casing is recorded in a rewritable nonvolatile memory, the user can easily grasp the dew condensation countermeasures according to the installation environment. still,
In the above-described embodiment, the humidity sensor illustrated in FIG. 3 is used, but the humidity sensor is not limited to this, and another sensor may be used. Further, a temperature sensor may be provided in addition to the humidity sensor, and the humidity sensor may be compensated for by using a temperature sensor or the like. Further, the humidity sensor 20
The heater 6 and the heater 6 do not necessarily need to be mounted on the control board 5 and may be arranged at the most effective positions in the casing 2 based on the structure of the casing 2 and the like. Further, in the above embodiment, PI control or the like is performed on the operation angle of the electric motor 4 using the positioner, but the configuration for this need not necessarily be accommodated in the casing. The present invention can be applied to a valve driving electric actuator that does not include a servo unit. In the above-described embodiment, the heater 6 is energized in accordance with a command from the humidity monitoring function circuit 207. However, the present invention is not limited to this. The heater 6 may be energized in addition to when there is a command from the humidity monitoring function circuit 207, for example, in a time zone where dew condensation is likely to occur.

[0011]

As described above, according to the electric actuator for driving a valve according to any one of the first to fifth aspects, the electric motor and the electric components for driving and controlling the electric motor are housed. Humidity inside the casing is detected,
Since the energization control of the heater housed in the casing is performed based on the detected humidity in the casing, even if the outside air temperature near the installation location of the electric actuator for driving the valve suddenly changes, the inside of the casing is not changed. Thus, the occurrence of dew condensation can be reliably prevented. Moreover,
According to the valve driving electric actuator according to the second aspect, in addition to the heater energization control based on the humidity in the casing, the control based on the operation angle of the electric motor is stopped, and a predetermined operation signal is transmitted to the electric motor. Since the process given to the motor drive circuit that drives the motor is performed, it is possible to prevent dangerous operation from being performed even if the electric motor or the electric component has a failure or malfunction due to dew condensation. Also,
According to the third aspect of the present invention, since the process of notifying the humidity state inside the casing to the outside is further performed, the user can quickly grasp the state inside the casing. Further, according to the valve driving electric actuator according to the fourth aspect, even if a predetermined time or more has elapsed after the energization of the heater is started, if the humidity in the casing does not fall below the set humidity, Since it is notified to the outside that there is an abnormality in the casing, the user can quickly perform maintenance. According to the valve driving electric actuator of the fifth aspect, the history of the humidity in the casing is recorded in the rewritable nonvolatile memory, so that the user can easily take a countermeasure against dew condensation according to the installation environment. You can figure out.

[Brief description of the drawings]

FIG. 1 is a view for explaining a schematic configuration of an entire valve driving electric actuator according to an embodiment of the present invention.

FIG. 2 is a functional block diagram for explaining a positioner built in the electric actuator for driving a valve.

FIG. 3 is a diagram illustrating a configuration of a humidity sensor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electric actuator for valve drive 2 ... Casing 3 ... Valve shaft 4 ... Electric motor 5 ... Control board 6 ... Heater 21 ... Cover 22 ... O-ring 32 ... Limit cam 51 ... Limit switch 52 ... Potentiometer 201 ... Generation of operation angle feedback signal Unit 204 ... Judgment circuit 205 ... Motor drive circuit 206 ... Humidity sensor 207 ... Humidity monitoring function circuit 208 ... Non-volatile memory 210 ... Humidity detection signal generation circuit 211 ... Communication circuit

Claims (5)

[Claims] An electric actuator for driving a valve in which an electric motor for driving a valve, an electric component for driving and controlling the electric motor, and a heater for raising a temperature are housed at least in a casing. And a humidity detecting means for detecting the humidity of the casing, and a dew condensation preventing means for controlling energization of the heater based on the humidity in the casing detected by the humidity detecting means. Electric actuator for driving. 2. The electric component, comprising: an operation angle detection means for detecting an operation angle of the electric motor; and a control signal for the electric motor based on the operation angle of the electric motor detected by the operation angle detection means. A positioner including a control circuit for generating the electric motor and a motor drive circuit for driving the electric motor based on a control signal generated by the control circuit, wherein the dew-condensation prevention processing means includes a control circuit for controlling the dew condensation. A process of stopping the control based on the operation angle of the electric motor and sending a predetermined operation signal from the control circuit to the motor drive circuit,
The electric actuator for driving a valve according to claim 1, wherein the operation is further performed based on the humidity in the casing detected by the humidity detecting means. 3. The method according to claim 1, wherein the dew-condensation prevention processing means further performs processing for notifying the humidity state in the casing to the outside based on the humidity in the casing detected by the humidity detection means. 3. The electric actuator for driving a valve according to claim 1. 4. When the humidity in the casing detected by the humidity detecting means does not fall below a set humidity even when a predetermined time or more has passed since the dew condensation preventing means started energizing the heater. The electric actuator for driving a valve according to any one of claims 1 to 3, further performing a process of notifying an outside that the casing has an abnormality. 5. The non-volatile memory according to claim 1, wherein said dew-condensation prevention processing means creates a history of humidity in said casing detected by said humidity detection means in a rewritable nonvolatile memory.
The electric actuator for driving a valve according to any one of claims 1 to 4.