JPH1061809A - Motor-driven valve actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively prevent the occurrence of dew condensation during a cold period without the occurrence of an excessive heating state during the daytime and a summer season by arranging a heater in a containing case for electrical equipment. SOLUTION: A heater 13 and a thermostat 14 to prevent the increase of temperature in a containing case 1 to a value higher than a specified temperature and the occurrence of dew condensation through ON and OFF of energization to the heater 13 through self-actuated control are arranged in the containing case 1 and a sever temperature increasing state in the containing case 1 when the heater 13 is always operated is prevented from occurring. Thereby, reversely, sufficient capacity is provided for the heater 13 and the actual effect of heating of an internal part during a cold period is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor-operated valve actuator which can be used outdoors, particularly suitably used in a piping section of a petroleum complex, a power plant, a building air conditioner or the like.

[0002]

2. Description of the Related Art Electric valve actuators used in piping sections of petroleum complexes, power plants, building air conditioners and the like are generally used outdoors. For this reason, a storage case for electrical components for controlling the electric motor is required to be waterproof and dustproof, and often has a closed structure. But,
Because the temperature difference in the outdoors is severe due to day and night and seasonal changes,
The inside of the storage case is easily condensed, and if left unchecked, a serious accident may occur due to failure or malfunction of electrical components. Therefore, a heater is usually attached to the electrical component storage case of the electric valve actuator having such a structure, and the heater is always energized to prevent dew condensation by warming the inside of the case.

[0003]

By the way, in the above-mentioned configuration, since the heater is always operated, the temperature rises excessively in the daytime or in summer when the outside air temperature is high, and the electric components and the case are damaged. May be given. For this reason, there is a restriction that the heater capacity must be determined in accordance with the maximum temperature rise. However, in this case, when the outside air temperature suddenly decreases at night or the like, the case temperature cannot be prevented from being reduced due to insufficient capacity of the heater, and dew condensation may occur. That is, when the temperature difference between the outside temperature and the outside temperature is large or when the temperature difference suddenly occurs, it is not enough as a measure to surely prevent dew condensation only by taking measures to always operate the heater.

The present invention has been made in view of such circumstances, and reliably prevents the occurrence of dew condensation in a storage case for electrical components even when the device is placed in a place where the outside temperature changes drastically. It is an object of the present invention to provide an electric valve actuator that can be used.

[0005]

In order to achieve the above object, the present invention provides an electric motor for driving a valve and accommodates electric components necessary for controlling the electric motor in a closed storage case. In the storage case, a heater that heats the inside of the storage case, a power supply to the heater is turned on and off by self-control, and the inside of the storage case is not heated to a certain temperature or more and condensation is formed. A switching element for maintaining the temperature in a temperature range that does not occur.

With such a configuration, the heater is operated by the switching element when the inside of the storage case approaches a temperature range where dew condensation is likely to occur, and the heater is operated by the switching element when the inside of the storage case reaches a certain high temperature. Is stopped, so that the inside of the storage case is not further heated when the outside air temperature is high, and there is no need to set the heater capacity based on such a high outside air temperature. For this reason, even if this electric valve actuator is arranged in a place where the outside air temperature rises sharply in the daytime or summertime, the necessary and sufficient capacity of the heater can be ensured and the occurrence of dew condensation in cold weather can be reliably prevented.

[0007]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an overall sectional view of an electric valve actuator according to the present embodiment, and FIG. 2 is a circuit diagram showing an electric system. In FIG. 1, many component parts constituting an electric valve actuator are incorporated in a closed storage case 1, and this storage case 1 has a first storage part 2 mainly storing drive system component parts. And a second storage unit 3 for storing the component parts of the control system. The first storage section 2 has a center column 4 connected to a valve shaft (not shown), an electric motor 5 for applying power to the center column 4, and an output of the electric motor 5 transmitted to the center column 4. A worm speed reducer 6 for driving a valve shaft (not shown) in a direction perpendicular to the paper surface and a limit switch mechanism 7 for detecting an overload state, an excessive displacement, and the like are incorporated.

On the other hand, in order to control the electric motor 5, component parts such as a transformer 8, an electromagnetic on-off valve 9, a printed board 10 and the like are supported by a support plate 10 a in the second storage section 3. At the same time, these component parts are connected to external wiring via a wiring inlet 11a of the terminal block 11, which also serves as insulation and sealing. The outline of the connection is as shown in FIG. 2. An external three-phase power supply 12 is connected to the electric motor 5 through an electromagnetic on-off valve 9, and the driving direction of the electromagnetic on-off valve 9 can be reversed.
A control power is taken from the three-phase power supply 12 via the transformer 8, and the power is supplied to the printed board 10. The printed board 10 includes circuits necessary for enabling interlock and remote control of the electric motor 5, and includes the above-described limit switch mechanism 7.
, A position limit signal and a torque limit signal are input, and an open / close signal is issued from the printed board 10 to the electromagnetic open / close valve 9.

In this embodiment, in this embodiment, a heater 13 for heating the inside of the storage case 1 and a thermostat 14 as a switching element for turning on and off the power supply to the heater 13 by self-control are provided in the storage case 1. Are provided. The heater 13 is inserted into a connection portion between the three-phase power supply 12 and the transformer 8, and has a spatial margin inside the storage case 1,
A portion having a small number of heating elements around the portion and capable of effectively heating the space, for example, on the support plate 10a or the first and second storage portions 2, 3
A flange inner wall portion 1a or the like that connects between them is selected. As the heater 13 of this embodiment, a heater having the ability to raise the internal temperature of the storage case 1 from 5 ° C. or lower to 40 ° C. or higher, for example, is used. On the other hand, the thermostat 14 is inserted in series with the heater 13 at a connection portion between the three-phase power supply 12 and the transformer 8, and is located at a location where dew condensation easily occurs first in the storage case 1. For example, the inner wall 1b of the bottom plate of the storage case 1 is selected. In the thermostat 14 of this embodiment,
One having a switching characteristic that turns on at 5 ° C. or lower and turns off at 40 ° C. or higher is used.

With this configuration, when the outside air temperature decreases and the temperature of the inner wall 1b of the storage case 1 falls below 5 ° C., the thermostat 14 is turned on and the heater 13 is activated. Then, the inside of the storage case 1 starts to be heated. On the other hand, the inner wall 1 of the storage case 1
If a situation occurs in which the temperature of b rises to 40 ° C. or higher, the thermostat 14 is turned off, and the operation of the heater 13 is stopped. For this reason, when this electric valve actuator is arranged in a place where the outside air temperature changes drastically, even if the outside air temperature rises in the daytime or summertime, the internal temperature of the storage case 1 rises at least greatly outside the outside air temperature. Therefore, it is possible to reliably prevent a burnout accident or the like due to excessive heating of the heater 13. Moreover,
If the outside temperature drops below freezing, for example,
Since the inside of the storage case 1 is maintained in a temperature range where dew condensation does not occur due to sufficient heating by the heater 13, an accident due to dew condensation, for example, a valve caused by conduction of contacts such as a solenoid switch 9 and a micro switch constituting the limit switch mechanism 7. Runaway,
It is possible to reliably prevent malfunctions due to oxidation, short-circuiting of the transformer 8 and the like, and to reliably improve the reliability of the electric valve actuator and, consequently, the safety of the entire plant system to which the electric valve actuator is applied. The effect is achieved.

The specific configuration of each part is not limited to only the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

[0012]

The present invention is embodied in the form described above and has the following effects. That is, in the electric valve actuator of the present invention, in a motor-operated valve actuator that can be used outdoors having an electric component for controlling an electric motor, a heater for preventing dew condensation occurring in a storage case of the electric component is set. A thermostat capable of automatically turning the heater on and off at a temperature is provided, and the heater is automatically operated by the thermostat only when the temperature in the storage case reaches a temperature range where dew condensation occurs. For this reason, even if a heater having a sufficient capacity is used, there is no problem that the heater operates when the outside air temperature is high and the temperature inside the storage case further rises excessively. It is possible to effectively achieve both prevention and prevention of a burnout accident caused by using a heater.

[Brief description of the drawings]

FIG. 1 is an overall perspective view showing one embodiment of the present invention.

FIG. 2 is a block diagram showing an electric system of the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Storage case 5 ... Electric motor 13 ... Heater 14 ... Switching element

Claims (1)

[Claims] An electric motor for driving a valve is provided, and electrical components required for controlling the electric motor are housed in a closed storage case. And a switching element that keeps the inside of the storage case in a temperature range that does not raise the temperature above a certain temperature and does not cause dew condensation by turning on and off the power supply to the heater by self-control. Electric valve actuator.