JP7197385B2 - Electric actuator and deterioration index calculation method - Google Patents

Description

The present invention relates to a spring-return type electric actuator, and more particularly to a deterioration index calculation technique for calculating a deterioration index used to determine the deterioration state of a power transmission section of an electric actuator.

As one of the electric actuators that electrically controls the opening and closing of operating ends such as valves and dampers, so-called spring return type actuators return the output shaft to a predetermined rotation position when the power supply is cut off by the restoring force of the return spring attached to the output shaft. electric actuator (see, for example, Patent Document 1).

When energized, the electric actuator rotates the output shaft with the motor through the power transmission section to adjust the opening of the operating end, and at the same time winds up the return spring to hold the rotating position by the detent torque of the motor. . As a result, when the power supply from the outside is cut off after that, the power supply to the electric clutch of the motor is stopped and the clutch is disconnected. The output shaft is forcibly returned to a predetermined rotational position such as a fully closed position or a fully opened position.

JP-A-10-164878 JP 2015-125038 A JP 2015-114188 A

A power transmission unit used in an electric actuator is usually composed of a reduction gear, and is considered to have sufficient durability over a long period of time. Therefore, there is little need to detect the state of deterioration of the power transmission unit, and conventionally, this function has not been embodied as a deterioration determination function for electric actuators.
On the other hand, field devices such as electric actuators have a warranty period, and must be replaced with a new one when the warranty period expires. However, in practice, it may be used for a long period of time beyond the warranty period.

If the actuator is used for a long period of time beyond the warranty period, the power transmission part of the electric actuator may deteriorate, and the power transmission torque originally designed may not be obtained due to failure or aging. In such a case, it may not be possible to accurately control the opening and closing of the operating end, or when the power supply is cut off, the return force of the return spring may make it impossible to reliably return the output shaft to a predetermined rotational position such as the fully closed position or the fully opened position. there's a possibility that. Therefore, it is important to grasp the state of deterioration of the power transmission unit.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a deterioration index calculation technique capable of easily calculating a deterioration index indicating the deterioration state of a power transmission unit of an electric actuator.

In order to achieve such an object, an electric actuator according to the present invention includes an output shaft for rotating a valve body, a motor for rotating the output shaft via a power transmission section, and a motor for driving the motor. a control circuit that controls the opening of the valve body by controlling; The control circuit includes an opening control unit that drives and controls the motor to rotate the output shaft to an arbitrary control opening, and a control circuit that rotates the output shaft to first and second control openings different from each other. a torque sum of the spring torque and the valve body torque generated in the return spring and the valve body at this time; and a motor torque generated in the motor when the output shaft is rotated to the second control opening. and a deterioration index processing unit that calculates the power transmission torque of the power transmission unit as the deterioration index of the power transmission unit based on.

In one configuration example of the electric actuator according to the present invention, the deterioration index processing unit causes the return spring and the valve body to rotate when the output shaft is rotated to the first and second control opening degrees. The torque sum is calculated based on the generated synthetic torque.

Further, in one configuration example of the electric actuator according to the present invention, the deterioration index processing unit calculates a difference between the first and second control opening degrees regarding the opening degree deviation of the output shaft and the valve body. The combined torque is calculated based on the opening deviation difference shown.

Further, one configuration example of the electric actuator according to the present invention includes an output-side angle sensor that detects the rotation angle of the output shaft as the output-side opening, and a rotation angle of the valve body that detects the valve-side opening. and a valve-side angle sensor, wherein the deterioration index processing unit detects the output-side angle sensor and the valve-side angle sensor when the output shaft is rotated to the first and second control opening degrees. The opening degree deviation difference is calculated based on the detected output side opening degree and the valve side opening degree.

Further, in one configuration example of the electric actuator according to the present invention, when the deterioration index processing unit rotates the output shaft to the first and second control opening degrees, the output side angle sensor detects The output side opening degree deviation indicating the opening degree deviation of the first and second output side opening degrees detected by the valve side angle sensor, and the opening degree deviation of the first and second valve side opening degrees detected by the valve side angle sensor. A valve-side opening deviation is calculated, and the difference between the output-side opening deviation and the valve-side opening deviation is calculated as the opening deviation difference.

Further, in one configuration example of the electric actuator according to the present invention, when the deterioration index processing unit rotates the output shaft to the first control opening, the output side angle sensor detects the second degree of opening. 1 and the first valve-side opening detected by the valve-side angle sensor; A second opening degree deviation between the second output side opening degree detected by the output side angle sensor and the second valve side opening degree detected by the valve side angle sensor when the valve is rotated to the second , and the difference between the first opening deviation and the second opening deviation is calculated as the opening deviation difference.

Further, in one configuration example of the electric actuator according to the present invention, the deterioration index processing unit sets the motor torque to Tm2, the opening deviation difference to Δθd, the lateral elastic modulus of the valve body, the cross-sectional secondary pole When the moment and the axial lengths of a series of connecting shafts connecting the electric actuator and the valve body are G, Ip, and L, respectively, the power transmission torque Td is calculated by the formula described later. is.

Further, in one configuration example of the electric actuator according to the present invention, the deterioration index processing unit controls the valve body torque generated in the valve body when the output shaft is held at the first control opening, The torque sum is calculated based on the spring torque generated in the return spring when the moving output shaft passes through the second control opening.

Further, in one configuration example of the electric actuator according to the present invention, when the deterioration index processing unit holds the output shaft at the first control opening, the motor and the return spring are affected. The valve body torque is calculated based on the torque and the spring torque.

In one configuration example of the electric actuator according to the present invention, the deterioration index processing unit sets the motor torques detected at the first control opening and the second control opening to Tm1 and Tm2, When the output-side openings of the output shaft detected by the first control opening and the second control opening are θa1 and θa2, and the spring constant of the return spring is k, the power transmission torque Td is calculated by the formula described later.

Further, a deterioration index calculation method according to the present invention includes an output shaft for rotating a valve body, a motor for rotating the output shaft via a power transmission section, and driving and controlling the motor to control the valve. A deterioration indicator used in an electric actuator comprising a control circuit for controlling the opening of the body, and a return spring attached to the output shaft to return the output shaft to a predetermined opening position by its own restoring force when power is cut off. A calculation method comprising: an opening degree control step in which an opening degree control section of the control circuit drives and controls the motor to rotate the output shaft to an arbitrary control opening degree; and a deterioration index processing section of the control circuit. is the sum of the spring torque and the valve body torque generated in the return spring and the valve body when the output shaft is rotated to the first and second control opening degrees different from each other, and the output shaft a deterioration index processing step of calculating the power transmission torque of the power transmission unit as a deterioration index of the power transmission unit based on the motor torque generated in the motor when the motor is rotated to the second control opening; It has

Further, in the deterioration index calculation method according to the present invention, in the deterioration index processing step, when the output shaft is rotated to the first and second control opening degrees, the combined Based on the torque, calculating the torque sum.

Further, in the deterioration index calculation method according to the present invention, the deterioration index processing step includes the valve body torque generated in the valve body when the output shaft is held at the first control opening, and calculating the torque sum based on the spring torque generated in the return spring when the output shaft passes through the second control opening.

According to the present invention, since the power transmission torque of the power transmission unit can be easily grasped as the deterioration index of the power transmission unit, the deterioration state of the power transmission unit can be easily grasped according to the deviation width from the initial design value. can do. Therefore, when the range of divergence increases and the deterioration progresses, appropriate countermeasures can be taken before a failure occurs, and extremely effective predictive maintenance can be realized. This makes it possible to provide a certain level of reliability even when long-term use beyond the warranty period is assumed. In addition, the deterioration index can be easily calculated using the existing configuration of the electric actuator, such as the angle sensor and control circuit, making it possible to improve the reliability of the electric actuator without increasing the circuit scale or product cost. becomes.

FIG. 1 is a block diagram showing the configuration of an electric actuator. FIG. 2 is a flow chart showing flow control processing. FIG. 3 is a graph showing the relationship between the valve-side sensor output value and the valve-side opening degree. FIG. 4 is a flowchart showing deterioration index processing according to the first embodiment. FIG. 5 is an explanatory diagram showing the deterioration index processing operation according to the first embodiment. FIG. 6 is an explanatory diagram showing another example of the deterioration index processing operation according to the first embodiment. FIG. 7 is a flowchart showing deterioration index processing according to the second embodiment. FIG. 8 is an explanatory diagram showing the deterioration index processing operation according to the second embodiment.

Next, embodiments of the present invention will be described with reference to the drawings.
[First embodiment]
First, an electric actuator 10 according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing the configuration of an electric actuator.

The electric actuator 10 is, for example, a device for electrically controlling a valve body such as a flow rate control valve that controls the flow rate of hot and cold water flowing through a pipe or an air volume adjustment damper that adjusts the air volume in equipment such as an air conditioning system. . In the following, as shown in FIG. 1, the case where the electric actuator 10 is attached to the valve body 20 of the flow control valve will be described as an example. It can be applied in the same way when it is attached to other equipment having a valve body.

[Valve body]
The valve body 20 is made of a metal tube in which a flow path 21 through which fluid flows is formed. A valve shaft 26 having one end led out of the valve main body 20 is connected to the valve body 22. By rotating the valve shaft 26, the valve body 22 rotates, and the cross-sectional area of the flow path 21 increases. That is, the valve opening degree is changed to control the flow rate of the fluid.

A pressure sensor S1 is arranged on the primary side (fluid upstream side) of the valve element 22 in the inner wall 23 of the flow path 21, and a pressure sensor S2 is arranged on the secondary side (fluid downstream side) of the valve element 22. It is These pressure sensors S<b>1 and S<b>2 detect the primary side pressure P<b>1 and the secondary side pressure P<b>2 of the flow path 21 , respectively, and output pressure detection signals indicating the obtained detection results to the electric actuator 10 . The flow rate of the fluid flowing through the flow path 21 is measured based on the primary side pressure P1, the secondary side pressure P2, and the current opening value θ, which is the output side opening θa corresponding to the valve opening.

[Electric actuator]
The electric actuator 10 is attached to the main body upper surface 24 of the valve body 20 via the yoke 31 , and controls the rotation of the output shaft 16 connected to the valve shaft 26 via the joint 30 to rotate the valve body 22 . It has a function of controlling the flow rate of the fluid by controlling the opening degree of the valve.
The main components of the electric actuator 10 include a setting circuit 11, a motor drive circuit 12, a motor 13, a power transmission section 14, a return spring 15, an output shaft 16, an output side angle sensor 17A, a valve side angle sensor 17V, and a memory circuit. 18 and a control circuit 19 are provided.

The setting circuit 11 has a function of acquiring a set value such as a flow rate target value Qref included in a setting signal such as a flow rate target signal received from a host device (not shown) and outputting the set value to the control circuit 19. .
The motor drive circuit 12 has a function of driving the motor 13 based on the motor control signal output from the control circuit 19 .

The motor 13 is a control motor such as a DC motor, an AC motor, or a stepping motor. and a clutch function for switching whether or not detent torque is generated depending on whether or not power is supplied to the electric actuator 10 from.
The power transmission unit 14 is composed of a power transmission mechanism such as a gearbox in which a plurality of gears having different numbers of teeth are meshed, and has a function of reducing the rotational speed of the shaft 13A of the motor 13 to rotate the output shaft 16. ing.

As a result, the drive signal is output from the motor drive circuit 12 to the motor 13 based on the motor control signal output from the control circuit 19 . In response to this drive signal, the shaft 13A of the motor 13 rotates, the rotational output of which is decelerated by the power transmission section 14 to rotate the output shaft 16, and the valve body 22 moves through the joint 30 and the valve shaft 26. It rotates to a predetermined rotation angle, that is, the valve opening degree.

The return spring 15 consists of a general coil spring, and is attached to the output shaft 16. When the power is cut off, the output shaft 16, which is released from the shaft 13A of the motor 13 by the power transmission section 14, is opened by its own restoring force. It is a spring that returns to the degree position.
The output shaft 16 is a shaft that is connected to the valve body 22 via a joint 30 and a valve shaft 26 to rotate the valve body 22 .

The output side angle sensor 17A is attached to the power transmission portion 14 or the output shaft 16, detects the rotation angle of the output shaft 16, and outputs the output side sensor output value Sa according to the rotation angle to the control circuit 19. It is an angle sensor.
In the following, a case where, for example, a circular differential transformer type angle sensor (Patent Document 2) or a magnetoresistive type angle sensor (Patent Document 3) is used as the output side angle sensor 17A will be described as an example. The present invention includes all the contents described in these Patent Documents 2 and 3. Note that the output angle sensor 17A is not limited to this, and a sensor capable of measuring a rotation angle, such as a potentiometer, incremental encoder, or absolute encoder, may be used as the output angle sensor 17A.

The valve-side angle sensor 17V is attached to the body upper surface 24 outside the valve body 20, detects the rotation angle of the valve shaft 26 in the vicinity of the valve body 22, and outputs the valve-side sensor output value Sv corresponding to the rotation angle. to the electric actuator 10 . The valve-side angle sensor 17V is attached to the valve main body 20 via a heat insulating material, and the influence of the fluid temperature is suppressed.
A temperature sensor S3 is attached to the valve-side angle sensor 17V, and based on the detected temperature Tx detected by the temperature sensor S3, the valve-side opening θv of the valve-side angle sensor 17V changes to the current opening value θ. Temperature compensated. Note that the temperature correction of the valve-side opening degree θv is not essential in this embodiment, and the temperature correction can be omitted if the sensor output of the valve-side angle sensor 17V is not affected by the ambient temperature.

In the following description, as the valve-side angle sensor 17V, for example, a circular differential transformer angle sensor (Patent Document 2) or a magnetoresistive angle sensor (Patent Document 3) is used. The present invention includes all the contents described in these Patent Documents 2 and 3. The valve-side angle sensor 17V is not limited to this, and a potentiometer, incremental encoder, absolute encoder, or other sensor capable of measuring a rotation angle may be used as the valve-side angle sensor 17V.

1, the mounting position of the valve-side angle sensor 17V may be the bottom surface 25 of the valve body 20 instead of the top surface 24 of the valve body.
When the valve body 22 is rotatably attached to the flow path 21 in the valve main body 20 , the upper and lower portions of the inner wall 23 engage the valve shaft 26 . Therefore, the lower end of the valve shaft 26 can be led out of the valve body 20 from the bottom surface 25 of the valve body 25, and the rotation angle of the lower end of the valve shaft 26 led out of the valve body 20 is detected by the valve side angle sensor 17V. should be detected by

The storage circuit 18 consists of a non-volatile semiconductor memory, and stores various processes used for flow rate control and deterioration index calculation, such as a characteristic table for specifying the flow rate coefficient Cv unique to the valve body 22 used for calculating the current flow rate value Q. It has the function of storing data. In this characteristic table, for each combination of the differential pressure ΔP=P1−P2 between the primary side pressure P1 and the secondary side pressure P2 of the flow path 21 and the current opening value θ of the valve body 22, A flow coefficient Cv is registered in advance. Each data of these characteristic tables is separately calculated based on the characteristics of the valve body 22 such as shape and material.

The control circuit 19 has a CPU and its peripheral circuits, and has the function of realizing various processing units that execute processing for flow rate control and deterioration index calculation by cooperating the CPU and programs. .
The control circuit 19 includes an opening control section 19A and a deterioration index processing section 19B as main processing sections.

The opening controller 19A controls the flow rate of the fluid flowing through the flow path 21 based on the primary side pressure P1 and the secondary side pressure P2 indicated by the pressure detection signals output from the pressure sensors S1 and S2 and the current opening value θ. By outputting a predetermined motor control signal to the motor drive circuit 12 based on the function of calculating the current flow rate Q and the flow rate deviation ΔQ between the current flow rate value Q and the target flow rate value Qref, the valve body 22 is opened. A function to control the flow rate current value Q by adjusting the degree and an arbitrary control opening degree when calculating the deterioration index, for example, to a first control opening degree θ1 and a second control opening degree θ2 that are preset and different from each other , and the function of rotating the output shaft 16 .

The deterioration index processing unit 19B detects the spring torque and the valve body generated in the return spring 15 and the valve body 22 when the output shaft 16 is rotated to the first control opening degree θ1 and the second control opening degree θ2 which are different from each other. As a deterioration index of the power transmission unit 14, the power transmission unit 14, and a function of determining the deterioration state of the power transmission unit 14 based on the obtained power transmission torque Td and the preset normal range E. .

Specifically, the deterioration index processing unit 19B has a function of calculating the torque sum Tw based on the combined torque Ts+Tv generated in the return spring 15 and the valve body 22 when the output shaft 16 is rotated to θ1 and θ2. and the opening degree deviation difference Δθd between θ1 and θ2, which indicates the difference in the opening degree deviation between the output shaft 16 and the valve body 22. A function of calculating an opening degree deviation difference Δθd based on the output side opening degrees θa1 and θa2 and the valve side opening degrees θv1 and θv2 detected by the output side angle sensor 17A and the valve side angle sensor 17V when rotating. have.

More specifically, when the output shaft 16 is rotated to θ1 and θ2, the deterioration index processing unit 19B detects an output side angle deviation θa2−θa1 of θa1 and θa2 detected by the output side angle sensor 17A. A function of calculating the opening degree deviation Δθa, a function of calculating the valve side opening degree deviation Δθv indicating the opening degree deviation θv2−θv1 of θv1 and θv2 detected by the valve side angle sensor 17V, and a function of calculating the opening degree deviation Δθv of these Δθa and Δθv. It has a function of calculating the difference Δθa−Δθv as the opening deviation difference Δθd.

Alternatively, when the output shaft 16 is rotated to θ1, the deterioration index processing unit 19B detects an opening degree deviation θa1− θa2 detected by the output side angle sensor 17A and θv2 detected by the valve side angle sensor 17V when the output shaft 16 is rotated to θ2. and a function of calculating the difference Δθav2−Δθav1 between Δθav1 and Δθav2 as the opening degree deviation difference Δθd.

Further, the deterioration index processing unit 19B has a function of calculating the motor torque Tm based on the motor current flowing through the motor 13 at the second control opening θ2, the motor torque being Tm, the opening deviation difference being Δθd, and the valve When G, Ip, and L denote the transverse elastic modulus of the body 22, the polar moment of inertia of the area, and the axial lengths of the series of connecting shafts that connect the electric actuator 10 and the valve body 22, respectively, the power transmission torque Td is is calculated by equation (3) to be described later. In addition, although the case where the motor torque is calculated based on the motor current will be described below as an example, the present invention is not limited to this, and the motor torque may be specified by other methods.

In the present invention, the first and second control openings θ1 and θ2 are target values used for opening control by the opening control section 19A, and the first and second output side openings θa1 and θa2 are output It is assumed to be a detection value indicating the rotation angle of the output shaft 16 detected by the side angle sensor 17A. Also, the first and second valve-side opening degrees θv1 and θv2 are assumed to be detection values indicating the rotation angle of the valve element 22 detected by the valve-side angle sensor 17V. The degree of opening is a percentage value between the fully closed state and the fully open state, and the rotation angle is a value that expresses the degree of opening as an angle. In the invention, the control opening degree, the output side opening degree, or the valve side opening degree may be simply referred to as the rotation angle.

[Flow rate control operation]
Next, with reference to FIG. 2, the flow control operation of the electric actuator 10 according to the present embodiment using the valve-side opening degree θv detected by the valve-side angle sensor 17V will be described. FIG. 2 is a flow chart showing flow control processing.
When controlling the flow rate of the fluid flowing through the flow path 21, the control circuit 19 executes the flow rate control process of FIG.

It is assumed that the setting circuit 11 is preset with a flow rate target value Qref at the start of the flow rate control process of FIG. It is also assumed that a characteristic table relating to the valve body 22 is registered in advance in the storage circuit 18 .
A storage unit (not shown) in the control circuit 19 stores a valve-side output reference value that serves as a reference for the correspondence between the valve-side sensor output value Sv of the valve-side angle sensor 17V and the valve opening degree of the valve body 22. It is assumed that Ss is set in advance.

FIG. 3 is a graph showing the relationship between the valve-side sensor output value and the valve-side opening degree. The circular differential transformer type angle sensor and magnetoresistive type angle sensor used as the valve-side angle sensor 17V are symmetrical in the fully closed direction and the fully open direction centering on the intermediate position angle of the valve shaft 26, that is, the 50% opening degree. It has a structure that outputs the valve-side sensor output value Sv. Therefore, as shown in FIG. 3, the relationship between the valve-side sensor output value Sv and the valve-side opening degree θv is linearly proportional, and the voltage value indicating fully closed and fully opened is the voltage value indicating 50% opening=0v are the voltage values -Ss and Ss apart from each other by an equal voltage width Ss.

First, the opening control unit 19A acquires the valve-side sensor output value Sv from the valve-side angle sensor 17V (step S100), and based on the preset valve-side output reference value Ss, the opening degree control unit 19A obtains the current value θ from Sv. (Valve side opening θv)=50×(1+Sv/Ss) [%] is calculated (step S101).

At this time, the current opening value θ of the valve-side angle sensor 17V (valve-side opening θv) is temperature-corrected based on the detected temperature Tx detected by the temperature sensor S3 attached to the valve-side angle sensor 17V. Note that the temperature correction of the current value θ is not essential in this embodiment, and the temperature correction can be omitted if the sensor output of the valve-side angle sensor 17V is not affected by the ambient temperature.

Next, the opening degree control unit 19A acquires the primary side pressure P1 and the secondary side pressure P2 indicated by the pressure detection signals output from the pressure sensors S1 and S2 (step S102). =P1-P2 is calculated (step S103).
Subsequently, the opening control unit 19A acquires the flow coefficient Cv corresponding to the differential pressure ΔP and the current opening value θ from the characteristic table of the storage circuit 18 (step S104), and based on the flow coefficient Cv and the differential pressure ΔP , the current flow rate Q of the fluid flowing through the flow path 21 is calculated (step S105). At this time, if A is a constant determined by the diameter of the flow path 21, etc., the current flow rate Q is obtained by Q=A.Cv.(.DELTA.P).sup.1/ ² .

After that, the opening controller 19A calculates the flow rate deviation ΔQ=Q−Qref between Q and Qref (step S106), and compares ΔQ with zero (step S107).
Here, when ΔQ is equal to zero and ΔQ=0 (step S107: ΔQ=0), the opening degree control unit 19A does not change the valve opening degree, but the flow rate target value Qref does not change. However, since the current flow rate Q changes depending on the state of the pipeline, the process returns to step S100.

On the other hand, when ΔQ is smaller than zero and ΔQ<0 (step S107: ΔQ<0), the opening control unit 19A outputs a predetermined motor control signal to the motor drive circuit 12 to set the motor 13 to ΔQ. The valve is driven in the opening direction by the corresponding valve opening degree (step S108), and the process returns to step S100.
Further, when ΔQ is greater than zero and ΔQ>0 (step S107: ΔQ>0), the opening controller 19A outputs a predetermined motor control signal to the motor drive circuit 12 to set the motor 13 to ΔQ. The valve is driven in the closing direction by the corresponding valve opening degree (step S109), and the process returns to step S100.

In the above, the flow rate control operation using the valve-side opening θv detected by the valve-side angle sensor 17V was described with reference to FIG. A flow rate control operation may be performed using the output side opening θa.

Specifically, in steps S100-S101 of FIG. 2, the output side sensor output value Sa is obtained from the output side angle sensor 17A (step S100), and based on the preset output side output reference value Sb, Sa current value θ (output side opening θa)=50×(1+Sa/Sb) [%] is calculated (step S101). Note that an output-side output reference value serving as a reference for the correspondence relationship between the output-side sensor output value Sa of the output-side angle sensor 17A and the valve opening degree of the valve body 22 is stored in a storage unit (not shown) in the control circuit 19. It is assumed that Sb is set in advance.

The output-side output reference value Sb is used instead of the valve-side output reference value Ss. When a circular differential transformer type angle sensor or a magnetic resistance type angle sensor is used as the output side angle sensor 17A, the relationship between the output side sensor output value Sa and the output side opening θa is linear, as in FIG. In addition to being proportional, the voltage values indicating fully closed and fully open are voltage values −Sb, Sb separated by an equal voltage width Sb centering on the voltage value indicating 50% opening=0v.
Other steps in FIG. 2 are the same as described above, and descriptions thereof are omitted here.

[Deterioration index processing operation]
Next, the deterioration index processing operation of the electric actuator 10 according to the present embodiment will be described with reference to FIGS. 4 and 5. FIG. FIG. 4 is a flowchart showing deterioration index processing according to the first embodiment. FIG. 5 is an explanatory diagram showing the deterioration index processing operation according to the first embodiment.

When calculating the deterioration index of the power transmission unit 14, the control circuit 19 executes the deterioration index processing of FIG. As shown in FIG. 5, the first and second control openings θ1 and θ2 for rotating the output shaft 16 when calculating the deterioration index are set in advance, and in this example, θa1<θa2. .

First, the opening controller 19A drives the motor 13 by outputting a predetermined motor control signal to the motor drive circuit 12, and rotates the output shaft 16 to the control opening θ1 and holds it (step S150). .
Next, the deterioration index processor 19B acquires the output side opening θa1 obtained from the output side sensor output value Sa of the output side angle sensor 17A while the output shaft 16 is held at the control opening θ1. At the same time, the valve-side opening degree θv1 obtained from the valve-side sensor output value Sv of the valve-side angle sensor 17V is acquired (step S151).

Thereafter, the opening controller 19A drives the motor 13 by outputting a predetermined motor control signal to the motor drive circuit 12 to rotate the output shaft 16 from the control opening θ1 to the control opening θ2. start (step S152).
Next, when the output shaft 16 passes through the control opening θ2, the deterioration index processing unit 19B acquires the output opening θa2 obtained from the output sensor output value Sa of the output angle sensor 17A. The valve-side opening degree θv2 obtained from the valve-side sensor output value Sv of the valve-side angle sensor 17V is obtained (step S153), and the motor torque Tm2 is obtained based on the motor current flowing through the motor 13 (step S154). .

Subsequently, the deterioration index processing unit 19B calculates the output side opening deviation Δθa (=θa2−θa1) based on the difference between the output side opening θa1 and the output side opening θa2 obtained from the output side sensor output value Sa. is calculated (step S155), and based on the difference between the valve-side opening degree θv1 and the valve-side opening degree θv2 obtained from the valve-side sensor output value Sv, the valve-side opening degree deviation Δθv (= θv2 - θv1) is calculated. Calculate (step S156).

Thereafter, the deterioration index processing unit 19B calculates an opening degree deviation difference Δθd (=Δθa−Δθv) based on the difference between the output side opening degree deviation Δθa and the valve side opening degree deviation Δθv (step S157). Based on the deviation difference Δθd, the lateral elastic modulus G, the polar moment of inertia Ip relating to the valve body 22, and the axial length L indicating the length of a series of connecting shafts connecting the electric actuator 10 and the valve body 22, A torque sum Tw is calculated (step S158), and a power transmission torque Td is calculated based on the motor torque Tm2 and the torque sum Tw (step S159).

Normally, when the output shaft 16 is rotating, the torques generated by the motor 13, the power transmission section 14, the return spring 15, and the valve body 22 are in balance with each other, and the sum of these torques is zero. becomes. As shown in FIG. 5, for example, the motor torque of the motor 13 at an arbitrary control opening θ is Tm2, the spring torque of the return spring 15 is Ts2, the power transmission torque in the power transmission unit 14 is Td, and the valve body 22 , the balance of these torques at an arbitrary control opening θ is expressed by the following equation (1).

On the other hand, when a fluid load is applied to the valve body 22, the return spring 15 and the valve body 22, which are connected via a series of connecting shafts including the output shaft 16, the joint 30, and the valve shaft 26, A twist occurs between the output-side opening θa obtained from the output-side sensor output value Sa of the output-side angle sensor 17A and the valve-side opening θv obtained from the valve-side sensor output value Sv of the valve-side angle sensor 17V. There is a discrepancy between them.

Between the control openings θ1 and θ2, the difference between the output side opening deviation Δθa (= θa2 - θa1) and the valve side opening deviation Δθv (= θv2 - θv1) is defined as the opening deviation difference Δθd. , where G is the transverse elastic modulus of the valve body 22, Ip is the polar moment of area, and L is the axial length indicating the length of the connecting shaft, the sum of the torques of the return spring 15 and the valve body 22 is Tw, That is, the combined torque Ts2+Tv is represented by the following equation (2).

Therefore, based on these formulas (1) and (2), the power transmission torque Td is expressed by the following formula (3). Thus, it can be seen that the power transmission torque Td can be calculated from the opening deviation difference Δθd and the motor torque Tm2.

After that, the deterioration index processing unit 19B compares the obtained power transmission torque Td with a preset normal range E of the power transmission torque Td (step S160). If there is (step S160: YES), it is determined that the deterioration state of the power transmission unit 14 is normal (step S161), and the series of deterioration index processing ends. The normal range E may be determined based on the initial value and allowable range of the power transmission torque Td calculated when the power transmission section 14 is designed.

On the other hand, when the power transmission torque Td is outside the normal range E (step S160: NO), it is determined that the deterioration state of the power transmission unit 14 is abnormal (step S162), and the series of deterioration index processing is terminated. . The deterioration index processing unit 19B may display an alarm on the obtained deterioration state determination result on a display unit (not shown) using an LCD or LED, or may notify the higher-level device of the deterioration state determination result by data communication.

At this time, the deterioration index processing unit 19B may periodically calculate the temporal change of the power transmission torque Td and sequentially notify the higher-level device of the change by data communication. Furthermore, the deterioration index processing unit 19B sequentially stores the calculated power transmission torque Td in the storage circuit 18 as time-series data, and estimates the future power transmission torque Td based on the approximation function generated from this time-series data. The value Td' may be estimated, and the timing at which the estimated value Td' departs from the normal range E may be predicted as a point of caution. This makes it possible to predict when the power transmission unit 14 will deteriorate, that is, when it should be replaced.

4 and 5, the case where the opening degree deviation difference Δθd is calculated based on the output side opening degree deviation Δθa and the valve side opening degree deviation Δθv has been described as an example, but the present invention is not limited to this. For example, the opening degree deviation difference Δθd can be calculated based on the deviation between the output side opening degrees θa1 and θa2 and the valve side opening degrees θv1 and θv2 in the control opening degrees θ1 and θ2, that is, the opening degree deviations Δθav1 and Δθav2. good.

FIG. 6 is an explanatory diagram showing another example of the deterioration index processing operation according to the first embodiment. In this example, the output shaft 16 is rotated to the control opening degrees θ1 and θ2, the output side opening degrees θa1 and θa2 and the valve side opening degrees θv1 and θv2 are obtained, and the respective opening degree deviations Δθav1 (=θa1 −θv1: first opening deviation) and Δθav2 (=θa2−θv2: second opening deviation), and based on these opening deviations Δθav1 and Δθav2, the opening deviation difference Δθd (=θav2−θav1 ) can be calculated.

[Effects of the first embodiment]
Thus, in the present embodiment, the opening controller 19A drives and controls the motor 13 to rotate the output shaft 16 to an arbitrary control opening θ, and the deterioration index processor 19B controls the output shaft 16 to the first and second control opening degrees θ1 and θ2, the torque sum Tw of the spring torque and the valve body torque generated in the return spring 15 and the valve body 22, and the output shaft 16 to the second The power transmission torque Td of the power transmission unit 14 is calculated as a deterioration index of the power transmission unit 14 based on the motor torque Tm2 generated in the motor 13 when it rotates to the control opening θ2 of be.

If the electric actuator 10 is used for a long period of time beyond the warranty period, the power transmission unit 14 may deteriorate, and the power transmission torque Td originally designed may not be obtained due to failure or aging. If the initial design power transmission torque Td cannot be obtained, the operating end cannot be controlled to open and close with high accuracy, or if the power supply is interrupted, the return force of the return spring 15 will move the output shaft 16 to a predetermined position such as the fully closed position or the fully open position. There is a possibility that it may not be possible to reliably return to the rotation position of . Therefore, it is important to grasp the deterioration state of the power transmission section 14 .

According to the present embodiment, since the power transmission torque Td of the power transmission unit 14 can be easily grasped as the deterioration index of the power transmission unit 14, the power transmission torque Td of the power transmission unit 14 can be determined according to the deviation from the initial design value. The state of deterioration can be easily grasped. Therefore, when the range of divergence increases and the deterioration progresses, appropriate countermeasures can be taken before a failure occurs, and extremely effective predictive maintenance can be realized. This makes it possible to provide a certain level of reliability even when long-term use beyond the warranty period is assumed. In addition, the deterioration index can be easily calculated using the existing configuration of the electric actuator 10, such as the output side angle sensor 17A, the valve side angle sensor 17V, the control circuit 19, etc., without increasing the circuit scale and product cost. , the reliability of the electric actuator 10 can be enhanced.

In addition, by monitoring the change over time of the power transmission torque Td with the deterioration index processing unit 19B or a host device, the deterioration time of the power transmission unit 14, that is, the replacement time, can be predicted, and the predictive maintenance of the electric actuator 10, valves, dampers, etc. can be performed. very useful for Further, although the degree of opening of the valve body 22 temporarily changes during the deterioration index calculation, the required time is extremely short as the degree of opening is detected by the output-side angle sensor 17A and the valve-side angle sensor 17V. Therefore, depending on the application, the deterioration index calculation can be performed even during normal driving operation. Therefore, by periodically executing the deterioration index processing operation, it is possible to quickly detect a change in the deterioration state of the power transmission unit 14 and take prompt action.
Moreover, according to the present embodiment, the spring constant k of the return spring 15 is not required when obtaining the power transmission torque Td, as in the second embodiment described later. Therefore, it is possible to obtain the power transmission torque Td that is not affected by aging of the spring constant k.

Further, in the present embodiment, the deterioration index processing unit 19B calculates the torque sum Tw based on the combined torque Ts+Tv generated in the return spring 15 and the valve body 22 when the output shaft 16 is rotated to θ1 and θ2. It may be calculated. More specifically, the combined torque Ts+Tv is calculated based on the opening degree deviation difference Δθd indicating the difference regarding the opening degree deviation of the output shaft 16 and the valve body 22 between the first and second control opening degrees θ1 and θ2. It may be calculated.
As a result, without requiring a configuration for directly measuring the combined torque Ts+Tv, it can be easily calculated based on the easily obtained physical quantity of the opening degree deviation of the output shaft 16 and the valve body 22.

Further, in the present embodiment, the output side angle sensor 17A that detects the rotation angle of the output shaft 16 as the output side opening degree θa and the valve side angle sensor 17A that detects the rotation angle of the valve body 22 as the valve side opening degree θv When the deterioration index processing unit 19B rotates the output shaft 16 to the first and second control opening degrees θ1 and θ2, the output side angle sensor 17A and the valve side angle sensor 17V detect the deterioration index processing unit 19B. The opening degree deviation difference Δθd may be calculated based on the output side opening degrees θa1 and θa2 and the valve side opening degrees θv1 and θv2. As a result, the opening degree deviation difference Δθd can be calculated with a very simple configuration including the output side angle sensor 17A and the valve side angle sensor 17V.

Further, in the present embodiment, when the deterioration index processing unit 19B rotates the output shaft 16 to the first and second control opening degrees θ1 and θ2, the first and second degrees detected by the output side angle sensor 17A Output-side opening degree deviation Δθa indicating the opening degree deviation of the second output-side opening degrees θa1 and θa2, and the opening degree deviation of the first and second valve-side opening degrees θv1 and θv2 detected by the valve-side angle sensor 17V , and the difference between the output side opening deviation Δθa and the valve side opening deviation Δθv may be calculated as the opening deviation difference Δθd. This makes it possible to calculate the opening degree deviation difference Δθd with extremely simple arithmetic processing.

Further, in the present embodiment, when the deterioration index processing unit 19B rotates the output shaft 16 to the first control opening degree θ1, the first output side opening degree θa1 detected by the output side angle sensor 17A is , the first opening degree deviation Δθav1 indicating the opening degree deviation from the first valve side opening degree θv1 detected by the valve side angle sensor 17V, and the output shaft 16 is rotated to the second control opening degree θ2. At this time, a second opening degree indicating the opening degree deviation between the second output side opening degree θa2 detected by the output side angle sensor 17A and the second valve side opening degree θv2 detected by the valve side angle sensor 17V. Δθav2, and the difference between the first opening deviation Δθav1 and the second opening deviation Δθav2 may be calculated as the opening deviation difference Δθd. This makes it possible to calculate the opening degree deviation difference Δθd with extremely simple arithmetic processing.

Further, in the present embodiment, the deterioration index processing unit 19B calculates the motor torque Tm based on the motor current flowing through the motor 13 when the output shaft 16 is rotated to the second control opening θ2. can be As a result, the motor torque Tm can be calculated by extremely simple arithmetic processing.

Further, in the present embodiment, the deterioration index processing unit 19B sets the motor torque to Tm2, the opening degree deviation difference to Δθd, the lateral elastic modulus and the secondary polar moment of area regarding the valve body 22, and the electric actuator 10 and the valve If the shaft lengths of a series of connecting shafts that connect the body 22 are G, Ip, and L, respectively, the power transmission torque Td may be calculated by the above-described formula (3). As a result, the power transmission torque Td can be calculated with extremely simple arithmetic processing.

[Second embodiment]
Next, an electric actuator 10 according to a second embodiment of the invention will be described.
In the first embodiment, when calculating the power transmission torque, the return spring 15 and the valve body 22 A case has been described in which the torque sum Tw of the spring torque and the valve body torque generated in , is calculated based on the combined torque Ts+Tv generated in the return spring 15 and the valve body 22 . In the present embodiment, the valve body torque Tv generated in the valve body 22 when the output shaft 16 is held at the first control opening degree θ1 A case will be described where the torque sum Tw is calculated based on the spring torque Ts2 generated in the return spring 15 when it passes.

That is, in the present embodiment, the deterioration index processing unit 19B measures the valve body torque Tv generated in the valve body 22 when the output shaft 16 is held at the first control opening θ1 and the output shaft 16 during rotation. The function of calculating the torque sum Tw based on the spring torque Ts2 generated in the return spring 15 when passes through the second control opening θ2, and the output shaft 16 was held at the first control opening θ1 It also has a function of calculating the valve element torque Tv based on the motor torque Tm1 and the spring torque Ts1 generated in the motor 13 and the return spring 15 at this time.

Specifically, the deterioration index processing unit 19B sets the motor torque detected at the first control opening θ1 and the second control opening θ2 to Tm1 and Tm2, and sets the motor torque detected at the first control opening θ1 and the second control opening θ2 to Assuming that the output side opening deviation indicating the opening deviation of the output side opening θ of the output shaft 16 detected at the control opening θ2 is Δθa and the spring constant of the return spring 15 is k, the power transmission torque Td will be described later. and a function of calculating by the formula (7).
In addition, in the electric actuator 10 according to the present embodiment, the valve-side angle sensor 17V is not required in the deterioration index processing operation, but other configurations are the same as those in FIG. 1, and detailed description thereof will be omitted here. do. Also, the flow control operation in the electric actuator 10 according to the present embodiment is the same as the flow control processing in FIG. 2 described above, and detailed description thereof will be omitted here. 2, the output sensor output value Sa of the output angle sensor 17A may be used instead of the valve sensor output value Sv of the valve angle sensor 17V, as described above.

[Deterioration index processing operation]
Next, the deterioration index processing operation of the electric actuator 10 according to the present embodiment will be described with reference to FIGS. 7 and 8. FIG. FIG. 7 is a flowchart showing deterioration index processing according to the second embodiment. FIG. 8 is an explanatory diagram showing the deterioration index processing operation according to the second embodiment.

When calculating the deterioration index of the power transmission unit 14, the control circuit 19 executes the deterioration index processing of FIG. As shown in FIG. 8, the first and second control openings θ1 and θ2 for rotating the output shaft 16 when calculating the deterioration index are set in advance, and in this example, θa1<θa2. .

First, the opening controller 19A drives the motor 13 by outputting a predetermined motor control signal to the motor drive circuit 12, and rotates the output shaft 16 to the control opening θ1 and holds it (step S200). .
Next, the deterioration index processor 19B acquires the output side opening θa1 obtained from the output side sensor output value Sa of the output side angle sensor 17A while the output shaft 16 is held at the control opening θ1. (Step S201).

Subsequently, the deterioration index processing unit 19B calculates the motor torque Tm1 based on the motor current flowing through the motor 13, and calculates the spring torque Ts1 based on the spring constant k of the return spring 15 and the output side opening θa1. (step S202), and based on these motor torque Tm1 and spring torque Ts1, the valve body torque Tv of the valve body 22 is calculated (step S203).

Thereafter, the opening controller 19A drives the motor 13 by outputting a predetermined motor control signal to the motor drive circuit 12 to rotate the output shaft 16 from the control opening θ1 to the control opening θ2. start (step S204).
Next, when the output shaft 16 passes through the control opening θ2, the deterioration index processing unit 19B acquires the output opening θa2 obtained from the output sensor output value Sa of the output angle sensor 17A (step S205).

Subsequently, the deterioration index processing unit 19B calculates the motor torque Tm2 based on the motor current flowing through the motor 13, and calculates the spring torque Ts2 based on the spring constant k of the return spring 15 and the output side opening θa2. (step S206), calculate the torque sum Tw based on the valve element torque Tv and the spring torque Ts2 (step S207), and calculate the power transmission torque Td based on the torque sum Tw and the motor torque Tm2. (Step S208).

Normally, when the output shaft 16 is held at an arbitrary opening, the torques generated by the motor 13, the power transmission section 14, the return spring 15, and the valve body 22 are in balance with each other, and the sum of these torques is becomes zero. As shown in FIG. 8, for example, when the motor torque of the motor 13 at the control opening θ1 is Tm1, the spring torque of the return spring 15 is Ts1, and the valve body torque of the valve body 22 is Tv, the output shaft 16 is Since the power transmission torque Td in the power transmission unit 14 is zero when the control opening θ1 is maintained, the balance of these torques at the control opening θ1 is expressed by the following equation (4).

Here, the spring torque Ts1 at the control opening θ1 is obtained by multiplying the spring constant k of the return spring 15 by the output side opening θa1 at the control opening θ1. ).

Further, the spring torque Ts2 at the control opening θ2 is also obtained by multiplying the spring constant k of the return spring 15 by the output side opening θa2 at the control opening θ2. When the deviation θa2−θa1 is Δθa, the torque sum Tw representing the sum of the valve body torque Tv and the spring torque Ts2 is expressed by the following equation (6).

On the other hand, since the torque balance at the control opening θ2 is represented by the above-mentioned formula (1), based on these formulas (1) and (6), the power transmission torque Td is expressed by the following formula (7) is represented by Thus, it can be seen that the power transmission torque Td can be calculated from the motor torques Tm1 and Tm2, the spring constant k of the return spring 15, and the opening deviation difference Δθd.

Thereafter, the deterioration index processing unit 19B compares the obtained power transmission torque Td with a preset normal range E of the power transmission torque Td (step S209), and determines that the power transmission torque Td is within the normal range E. If there is (step S209: YES), it is determined that the deterioration state of the power transmission unit 14 is normal (step S210), and the series of deterioration index processing ends. The normal range E may be determined based on the initial value and allowable range of the power transmission torque Td calculated when the power transmission section 14 is designed.

On the other hand, if the power transmission torque Td is outside the normal range E (step S209: NO), it is determined that the deterioration state of the power transmission unit 14 is abnormal (step S211), and the series of deterioration index processing is terminated. . The deterioration index processing unit 19B may display an alarm on the obtained deterioration state determination result on a display unit (not shown) using an LCD or LED, or may notify the higher-level device of the deterioration state determination result by data communication.

At this time, the deterioration index processing unit 19B may periodically calculate the temporal change of the power transmission torque Td and sequentially notify the higher-level device of the change by data communication. Furthermore, the deterioration index processing unit 19B sequentially stores the calculated power transmission torque Td in the storage circuit 18 as time-series data, and estimates the future power transmission torque Td based on the approximation function generated from this time-series data. The value Td' may be estimated, and the timing at which the estimated value Td' departs from the normal range E may be predicted as a point of caution. This makes it possible to predict when the power transmission unit 14 will deteriorate, that is, when it should be replaced.

[Effects of Second Embodiment]
As described above, in the present embodiment, the deterioration index processing unit 19B performs the valve body torque Tv generated in the valve body 22 when the output shaft 16 is held at the first control opening θ1, and the output during rotation. The torque sum Tw is calculated based on the spring torque Ts2 generated in the return spring 15 when the shaft 16 passes through the second control opening θ2.
Specifically, based on the motor torque Tm1 and the spring torque Ts1 generated in the motor 13 and the return spring 15 when the output shaft 16 is held at the first control opening θ1, the deterioration index processing unit 19B: It is designed to calculate the valve element torque Tv.

As a result, only the spring constant k is required when calculating the power transmission torque Td, and the lateral elastic modulus G, the polar moment of inertia Ip, and the , characteristic parameters such as the axial length L of a series of connecting shafts connecting the electric actuator 10 and the valve body 22 are not required. Therefore, it is possible to significantly reduce the burden of deriving these unique parameters, and to greatly simplify the calculation processing of the power transmission torque Td.

Further, in the present embodiment, the deterioration index processing unit 19B sets the motor torque detected at the first control opening θ1 and the second control opening θ2 to be Tm1 and Tm2, and the first control opening θ1 and If the output side opening deviation indicating the opening deviation of the output side opening θ of the output shaft 16 detected at the second control opening θ2 is Δθa, and the spring constant of the return spring 15 is k, the power transmission torque is Td may be calculated by the above-described formula (7). As a result, the power transmission torque Td can be calculated with extremely simple arithmetic processing.

[Expansion of Embodiment]
Although the present invention has been described with reference to the embodiments, the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

DESCRIPTION OF SYMBOLS 10... Electric actuator 11... Setting circuit 12... Motor drive circuit 13... Motor 13A... Shaft 14... Power transmission part 15... Return spring 16... Output shaft 17A... Output side angle sensor 17V... Valve Side angle sensor 18 Storage circuit 19 Control circuit 19A Opening degree control unit 19B Degradation index processing unit 20 Valve main body 21 Flow path 22 Valve body 23 Inner wall 24 Main body Upper surface 25 Body bottom 26 Valve shaft 30 Coupling 31 Yoke S1, S2 Pressure sensor S3 Temperature sensor Qref Target flow rate Q Current flow rate ΔQ Flow deviation Sa ... output side sensor output value, Sb ... output side output reference value, Sv ... valve side sensor output value, Ss ... valve side output reference value, Tx ... detected temperature, P1 ... primary side pressure, P2 ... secondary side pressure, ΔP Differential pressure θ, θ1, θ2 Control opening θa, θa1, θa2 Output side opening θv, θv1, θv2 Valve side opening Δθa Output side opening deviation Δθv Valve side opening Deviation, Δθav, Δθav1, Δθav2 ... opening degree deviation, Δθd ... opening degree deviation difference, Tm, Tm1, Tm2 ... motor torque, Td ... power transmission torque, Ts, Ts1, Ts2 ... spring torque, Tv ... valve body torque, Tw : sum of torque, G: modulus of transverse elasticity, Ip: polar moment of area, L: shaft length.

Claims (13)

an output shaft for rotating the valve body;
a motor that rotates the output shaft via a power transmission unit;
a control circuit that controls the opening of the valve body by driving and controlling the motor;
a return spring attached to the output shaft to return the output shaft to a predetermined opening position by its own restoring force when power is cut off;
The control circuit is
an opening control unit that drives and controls the motor to rotate the output shaft to an arbitrary control opening;
The torque sum of spring torque and valve body torque generated in the return spring and the valve body when the output shaft is rotated to first and second control opening degrees different from each other, and and a deterioration index processing unit for calculating the power transmission torque of the power transmission unit as a deterioration index of the power transmission unit based on the motor torque generated in the motor when the motor is rotated to the control opening of No. 2. An electric actuator characterized by: The electric actuator according to claim 1,
The deterioration index processing unit calculates the torque sum based on a combined torque generated in the return spring and the valve body when the output shaft is rotated to the first and second control openings. An electric actuator characterized by: The electric actuator according to claim 2,
The deterioration index processing unit calculates the combined torque based on an opening degree deviation difference indicating a difference between the opening degree deviations of the output shaft and the valve body between the first and second control opening degrees. An electric actuator characterized by: The electric actuator according to claim 3,
an output side angle sensor that detects the rotation angle of the output shaft as an output side opening;
a valve-side angle sensor that detects the rotation angle of the valve body as a valve-side opening,
The deterioration index processing unit detects the output side opening detected by the output side angle sensor and the valve side angle sensor when the output shaft is rotated to the first and second control openings and the An electric actuator, wherein the opening degree deviation difference is calculated based on the valve side opening degree. The electric actuator according to claim 4,
The deterioration index processing unit calculates the first and second output-side openings detected by the output-side angle sensor when the output shaft is rotated to the first and second control openings. An output side opening degree deviation indicating the deviation and a valve side opening degree deviation indicating the opening degree deviation of the first and second valve side opening degrees detected by the valve side angle sensor are calculated, and these output side opening degrees are calculated. An electric actuator, wherein a difference between a deviation and a valve-side opening deviation is calculated as the opening deviation difference. The electric actuator according to claim 4,
The deterioration index processing unit detects a first output-side opening detected by the output-side angle sensor and the valve-side angle sensor when the output shaft is rotated to the first control opening. A first opening degree deviation indicating an opening degree deviation from the first valve side opening degree detected by the output side angle sensor when the output shaft is rotated to the second control opening degree. A second opening degree deviation indicating an opening degree deviation between the second output side opening degree detected by the valve side angle sensor and the second valve side opening degree detected by the valve side angle sensor is calculated. An electric actuator, wherein a difference between a deviation and a second opening deviation is calculated as the opening deviation difference. The electric actuator according to claim 3,
The deterioration index processing unit sets the motor torque to Tm2, the opening degree deviation difference to Δθd, the lateral elastic modulus and the secondary polar moment of area related to the valve body, and connects the electric actuator and the valve body. An electric actuator, wherein the power transmission torque Td is calculated by the following equation, where G, Ip, and L are the lengths of a series of connecting shafts.

The electric actuator according to claim 1,
The deterioration index processing unit controls the valve body torque generated in the valve body when the output shaft is held at the first control opening, and The electric actuator, wherein the torque sum is calculated based on the spring torque generated in the return spring when it passes through. The electric actuator according to claim 8,
The deterioration index processing unit calculates the valve body torque based on motor torque and spring torque generated in the motor and the return spring when the output shaft is held at the first control opening. An electric actuator characterized by: The electric actuator according to claim 8,
The deterioration index processing unit sets the motor torque detected at the first control opening and the second control opening to Tm1 and Tm2, and sets the motor torque detected at the first control opening and the second control opening to Tm1 and Tm2. If the output side opening deviation indicating the opening deviation of the output side opening of the output shaft detected in is Δθa and the spring constant of the return spring is k, the power transmission torque Td is calculated by the following equation. An electric actuator characterized by:

an output shaft for rotating a valve body, a motor for rotating the output shaft via a power transmission section, a control circuit for controlling the opening of the valve body by driving and controlling the motor, A deterioration index calculation method used in an electric actuator including a return spring attached to an output shaft and returning the output shaft to a predetermined opening position by its own restoring force when power is cut off,
an opening control step in which the opening controller of the control circuit drives and controls the motor to rotate the output shaft to an arbitrary control opening;
When the deterioration index processing unit of the control circuit rotates the output shaft to first and second control opening degrees different from each other, the difference between the spring torque and the valve body torque generated in the return spring and the valve body. Power transmission torque of the power transmission unit is determined as a deterioration index of the power transmission unit based on the torque sum and the motor torque generated in the motor when the output shaft is rotated to the second control opening. and a deterioration index processing step of calculating In the deterioration index calculation method according to claim 11,
The deterioration index processing step is a step of calculating the torque sum based on the combined torque generated in the return spring and the valve body when the output shaft is rotated to the first and second control openings. A deterioration index calculation method, comprising: In the deterioration index calculation method according to claim 11,
In the deterioration index processing step, the valve disc torque generated in the valve disc when the output shaft is held at the first control opening degree and the output shaft during rotation is controlled by the second control opening degree. A deterioration index calculation method, comprising: calculating the torque sum based on the spring torque generated in the return spring when it passes.

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