JP7572230B2 - Actuator - Google Patents

Description

The present invention relates to an actuator, and more specifically to an actuator having multiple shafts connected by a coupling.

Actuators having a first shaft and a second shaft connected by a coupling are known. An example of such an actuator is a flow control valve. A flow control valve has an output shaft (first shaft) that is rotated by a motor, a valve shaft (second shaft) that is connected to the output shaft by a coupling, and a valve body that is connected to the valve shaft and controls the flow rate of the fluid flowing through the pipe. Such flow control valves may be equipped with a torque sensor that detects the valve body torque that rotates the valve body and valve shaft relative to the output shaft.

On the other hand, Patent Document 1 discloses an invention in which the torque applied to a rotating shaft is detected by a strain gauge and a strain generating part provided on the rotating shaft. Patent Document 1 also states (paragraph 0018) that this invention makes it unnecessary to use a shaft coupling on the load side.

JP 2016-8827 A

In an actuator having a torque sensor such as the flow control valve, the torque sensor is disposed between the first shaft and the second shaft, and two couplings are provided to connect the torque sensor to the first shaft and the second shaft, respectively. However, such a configuration has the problem that the overall axial length of the actuator becomes long. As mentioned above, Patent Document 1 states that a shaft coupling with the load side is not necessary, and according to this description, the overall axial length of the rotating shaft can be shortened, thereby solving the above problem. However, the invention described in Patent Document 1 is not a structure that assumes the use of multiple shafts such as the first shaft and the second shaft, and therefore cannot be applied to the actuator.

The present invention has been made in consideration of the above points, and aims to prevent the overall axial length of an actuator capable of detecting the torque that rotates a second shaft relative to a first shaft from becoming too long.

In order to solve the above problem, the actuator of the present invention comprises a first shaft, a second shaft coaxial with the first shaft, a coupling that connects the first shaft and the second shaft so that the first shaft and the second shaft rotate together, and a strain gauge that is disposed on the surface of the coupling and configured to detect strain that occurs on the surface when the second shaft rotates relative to the first shaft.

The coupling may have a first surface on which a first hole into which one end of the first shaft is inserted opens, a second surface on the opposite side to the first surface on which a second hole into which one end of the second shaft is inserted opens, and a third surface connecting the first surface and the second surface, and the strain gauge may be disposed on the third surface.

The coupling may be cylindrical and have a communication hole that connects the first hole and the second hole, the one end of the first shaft and the one end of the second shaft are spaced apart within the communication hole, and the strain gauge is disposed between the one end of the first shaft and the one end of the second shaft in the axial direction of the first shaft.

The actuator may further include a torque derivation unit configured to derive a torque applied to the second shaft based on the strain detected by the strain gauge, the first shaft being a drive shaft that is driven to rotate by a drive source, the second shaft being a driven shaft that rotates following the rotation of the first shaft to rotate a rotating object, and the torque may be applied to the second shaft due to a load on the rotating object.

The actuator may be a flow control valve, the rotating object may be a valve body that controls the flow rate of a fluid flowing through a pipe, and the torque applied to the second shaft may be a valve body torque applied to the valve body.

The actuator may further include a temperature sensor configured to detect a temperature in the vicinity of the strain gauge of the coupling, and the torque derivation unit may be configured to derive the torque based on the strain and the temperature detected by the temperature sensor.

The actuator may include the driving source, a control unit that controls the driving source, and a housing that houses the driving source and the control unit, and the torque derivation unit may be configured by a circuit board that is disposed outside the housing.

The circuit board may have a through hole or a notch through which the first shaft or the second shaft passes, and may be fixed to the coupling.

The control unit may be configured to communicate with the torque derivation unit via a wire and to supply power to the torque derivation unit via a wire.

The control unit may be configured to wirelessly communicate with the torque derivation unit and to wirelessly supply power to the torque derivation unit.

According to the present invention, since a strain gauge is disposed on the surface of the coupling that connects the second shaft and the first shaft, it is not necessary to provide a torque sensor between the second shaft and the first shaft separately from the coupling. Therefore, according to the present invention, the total axial length of the actuator is not increased. Furthermore, according to the present invention, the strain gauge detects the strain that occurs on the surface of the coupling when the second shaft rotates relative to the first shaft. This strain is due to the torque that rotates the second shaft relative to the first shaft. Therefore, it can be said that the strain gauge that detects the above-mentioned strain detects the torque that rotates the second shaft relative to the first shaft. As described above, according to the present invention, the total axial length of the actuator that can detect the torque that rotates the second shaft relative to the first shaft is prevented from increasing.

FIG. 1 is a block diagram showing a configuration of an actuator according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of a portion of the actuator of FIG. FIG. 3 is an enlarged elevational view of the vicinity of the coupling of the actuator of FIG. FIG. 4 is a flowchart of a torque derivation process executed by the first control unit in FIG. FIG. 5 is a block diagram showing a partial configuration of an actuator according to a modified example. FIG. 6 is a block diagram showing a partial configuration of an actuator according to a modified example. FIG. 7 is a block diagram showing a partial configuration of an actuator according to a modified example.

The actuator 10 according to the embodiment of the present invention will be described below with reference to Figs. 1 to 4. The actuator 10 according to the embodiment of the present invention is configured as a flow control valve that controls the flow rate of hot and cold water flowing through piping in equipment such as an air conditioning system. In the following description, the direction in which a first shaft 43 and a second shaft 44, which will be described later, extend as shown in Fig. 1 is the up-down direction, and the valve body 20, which will be described later, is the bottom. This up-down direction does not have to coincide with the actual top-bottom direction.

As shown in FIG. 1, the actuator 10 includes a valve body 20 that controls the flow rate of the fluid flowing therethrough, a drive unit 30 that drives the valve body 20, and a yoke 90 that is attached to the valve body 20 and supports the drive unit 30.

The valve body 20 comprises a cylindrical pipe fitting 21 that forms a flow path 21A through which a fluid flows, and a valve body 22 that is disposed inside the pipe fitting 21, i.e., midway through the flow path 21A. The valve body 22 is driven to rotate by a drive device 30. The valve body 22 changes the opening area of the flow path 21A by rotating, thereby controlling the flow rate of the fluid flowing through the flow path 21A.

The drive device 30 includes a drive mechanism 40 that drives the valve body 22, a control mechanism 50 that controls the drive mechanism 40, and a torque detection mechanism 60 that detects the valve body torque, which is the torque applied to the valve body 22. A part of the drive mechanism 40 and the control mechanism 50 are housed in a housing 31 of the drive device 30, and the torque detection mechanism 60 is disposed on a coupling 45 (described below) that is a component of the drive mechanism 40 and is disposed outside the housing 31.

The drive mechanism 40 that drives the valve body 22 includes a drive source 41, a first shaft 43, a second shaft 44, and a coupling 45.

The driving source 41 is a mechanism that drives and rotates the first shaft 43, and is configured to include a motor 41A and a reduction gear 41B. The motor 41A is not limited to a specific motor, and may be, for example, any of various control motors such as a DC motor, an AC motor, or a stepping motor. The motor 41A has a rotating shaft 41AA. The motor 41A is controlled by a control mechanism 50 and rotates the rotating shaft 41AA. The reduction gear 41B is a power transmission mechanism such as a gear box including multiple meshed gears with different numbers of teeth. The reduction gear 41B reduces the rotation of the rotating shaft 41AA of the motor 41A and transmits it to the first shaft 43, causing the first shaft 43 to rotate.

The first shaft 43 and the second shaft 44 have a rod shape. The first shaft 43 and the second shaft 44 are arranged coaxially, and their central axes are located on the same axis line. The first shaft 43 and the second shaft 44 are connected by a coupling 45. This connection allows the first shaft 43, the coupling 45, and the second shaft 44 to rotate as a unit. The valve body 22 of the valve body 20 is connected to the lower end of the second shaft 44. When the motor 41A rotates the first shaft 43 via the reducer 41B, this rotation is transmitted to the valve body 22 via the coupling 45 and the second shaft 44, and the valve body 22 rotates. Therefore, the first shaft 43 is a drive shaft that is driven and rotated by the drive source 41. The second shaft 44 is a driven shaft that rotates the valve body 22 as a rotating object by rotating following the rotation of the first shaft 43. The rotation angle of the valve body 22, i.e., the valve opening, is adjusted by the rotation angle of the rotating shaft 41AA of the motor 41A.

Here, the structures of the first shaft 43, the second shaft 44, and the coupling 45 will be described with reference to FIG. 2.

A gear 41BA constituting the reduction gear 41B is fixed to the first shaft 43. The first shaft 43 is rotatably supported by the lower part 31A of the housing 31 via a bearing B. A part of the lower end side of the first shaft 43 protrudes outside the housing 31.

The coupling 45 has an upper surface (first surface) 45B where the first hole 45A opens, a lower surface (second surface) 45D opposite the upper surface 45B where the second hole 45C opens, and a side surface (third surface) 45E connecting the upper surface 45B and the lower surface 45D. The first hole 45A and the second hole 45C communicate with each other to form a communication hole 45G. Therefore, the coupling 45 has a cylindrical shape with the inner wall of the communication hole 45G as the inner peripheral wall.

The lower end 43A of the first shaft 43 is inserted into the first hole 45A and fixed to the coupling 45. The upper end 44A of the second shaft 44 is inserted into the second hole 45C and fixed to the coupling 45. The lower end 43A of the first shaft 43 and the upper end 44A of the second shaft 44 are fixed in the communication hole 45G with a gap D between them, that is, facing each other at a distance. The fixing method of the lower end 43A and the upper end 44A is arbitrary. For example, the lower end 43A and the upper end 44A are fixed to the first hole 45A or the second hole 45C by being fastened to the coupling 45. For example, the lower end 43A and the upper end 44A have a D-shaped cross section, and are fastened to the coupling 45 by pressing the flat part of the D shape with a bolt (not shown) that penetrates the cylindrical coupling 45 in the radial direction. The fastening method is arbitrary, and may be clamp fastening, surface pressure fastening, pin fastening, or the like.

As shown in FIG. 1, the control mechanism 50 includes a signal processing circuit 51, a power supply circuit 52, a motor drive circuit 53, a rotational position sensor 54, and a first control unit 55.

The signal processing circuit 51 processes various signals to relay communication between the higher-level device UD and the first control unit 55. The signal processing circuit 51 receives an opening target signal indicating a target value for the opening of the valve body 22 from the higher-level device UD. The signal processing circuit 51 processes the input opening target signal, extracts the target value indicated by the opening target signal, and outputs it to the first control unit 55. Furthermore, when warning information described below is input from the first control unit 55, the signal processing circuit 51 generates a signal indicating the warning information and transmits it to the higher-level device UD.

The power supply circuit 52 converts the power supplied from the power supply PS into power for operating each part of the actuator 10 and outputs it. In particular, the power supply circuit 52 converts the power from the power supply PS into power for the motor drive circuit 53 and power for the first control unit 55, and supplies the converted power to the motor drive circuit 53 and the first control unit 55, respectively.

The motor drive circuit 53 operates using power from the power supply circuit 52 and drives the motor 41A based on a control signal from the first control unit 55, as described below.

The rotational position sensor 54 is attached to the reducer 41B, detects the rotational angle of the first shaft 43, and outputs the detected rotational angle to the first control unit 55. The rotational position sensor 54 may be any sensor capable of detecting the rotational angle. Examples of such sensors include a circular differential transformer type angle sensor, a magnetoresistive type angle sensor, a potentiometer, an incremental encoder, and an absolute encoder.

The first control unit 55 is composed of various computers such as a microcomputer, and controls the entire actuator 10. The first control unit 55 operates with power from the power supply circuit 52, and controls the driving of the motor 41A by the motor drive circuit 53 by supplying a control signal to the motor drive circuit 53. The first control unit 55 supplies a control signal to the motor drive circuit 53 based on the target value of the opening of the valve body 22 supplied from the signal processing circuit 51 and the rotation angle of the first shaft 43 supplied from the rotation position sensor 54, to bring the rotation angle of the first shaft 43 closer to the rotation angle corresponding to the target value. The motor drive circuit 53 drives the motor 41A according to the control signal. The first control unit 55 controls the motor 41A by such feedback control, and controls the rotation angle of the first shaft 43 so that the opening of the valve body 22 becomes the target value supplied from the upper device UD.

The first control unit 55 further supplies power to the torque detection mechanism 60 and acquires the torque value of the valve element torque described below from the torque detection mechanism 60. The first control unit 55 performs a predetermined operation when the acquired torque value of the valve element torque exceeds a predetermined threshold value. This will be described in detail after explaining the torque detection mechanism 60.

As shown in FIG. 1, the torque detection mechanism 60 that detects the valve body torque applied to the valve body 22 includes a strain gauge 61, a temperature sensor 62, an analog processing circuit 63, and a second control unit 64. The analog processing circuit 63 and the second control unit 64 are configured by a circuit board 65 shown in FIG. 2 and FIG. 3. The second control unit 64 is configured by a microcomputer and the like mounted on the circuit board 65. Note that in FIG. 2 and FIG. 3, the circuit board 65 is depicted in a simplified manner, and the circuit elements and the like that are actually mounted are omitted.

As shown in FIG. 3, the strain gauge 61 is disposed on the side 45E of the coupling 45. The strain gauge 61 is attached to the side 45E of the coupling 45 with an adhesive or the like, and detects the strain of the side 45E. The strain gauge 61 has a thin sheet-like electrical insulator and a metallic resistor formed in a folded pattern on the electrical insulator. The resistance value of the resistor of the strain gauge 61 changes according to the strain of the side 45E of the coupling 45. That is, the strain gauge 61 converts the strain into the resistance value of the resistor. The strain gauge 61 detects the strain by this conversion. Instead of the resistor, a semiconductor strain gauge having a semiconductor whose resistance value changes according to the strain may be adopted as the strain gauge 61. The resistance value of the resistor or semiconductor of the strain gauge 61, that is, the strain detected by the strain gauge 61, is output in the form of a voltage signal to the analog processing circuit 63 via two lead wires L1. The strain gauge 61 may be any detector as long as it can detect strain.

The distortion of the side surface 45E of the coupling 45 occurs when the second shaft 44 rotates relative to the first shaft 43, and the coupling 45 twists due to this relative rotation. This relative rotation occurs when the valve body torque applied to the valve body 22 is applied to the second shaft 44 through the valve body 22. Here, the valve body torque specifically refers to the torque that rotates the valve body 22 relative to the first shaft 43. The valve body torque also includes a force applied to the valve body 22 so as not to rotate the valve body 22 when the first shaft 43 rotates, that is, a torque that rotates the valve body 22 that tries to rotate together with the first shaft 43 in the opposite direction. Furthermore, the valve body torque includes a torque applied to the valve body 22 when the first shaft 43 is not rotating. Since the valve body torque is applied to the second shaft 44 through the valve body 22, it can also be said to be a torque that rotates the second shaft 44 relative to the first shaft 43. The strain gauge 61 detects the distortion of the side surface 45E to detect the torque that rotates the second shaft 44 relative to the first shaft 43.

Considering that the strain gauge 61 detects the strain on the side surface 45E of the coupling 45, the coupling 45 is made of a material that has sufficient strength to connect the first shaft 43 and the second shaft 44, but has a large surface strain. Examples of such materials include duralumin or super duralumin.

The position of the strain gauge 61 may be any position on the side surface 45E where distortion occurs. Here, as shown in FIG. 3, the strain gauge 61 is placed at a position (distance D) between the lower end 43A of the first shaft 43 and the upper end 44A of the second shaft 44 in the vertical direction. This position is also a part where the twist or distortion is large, so by placing the strain gauge 61 at this position, distortion can be detected with high accuracy. The strain gauge 61 may be placed on the surface of the coupling 45, and may be provided on the inner surface of the communication hole 45G (this surface is also considered as the surface). The strain gauge 61 may be placed on the inner surface of the communication hole 45G between the lower end 43A of the first shaft 43 and the upper end 44A of the second shaft 44. In this case, the two lead wires L1 are routed through holes or cutouts formed in the coupling 45.

The temperature sensor 62 is provided near the strain gauge 61 on the side surface 45E of the coupling 45, and detects the temperature near the strain gauge 61 in the coupling 45. The temperature sensor 62 may be a thermistor or the like whose resistance value changes depending on the temperature. The temperature sensor 62 detects the temperature by converting the temperature into a resistance value. The resistance value of the temperature sensor 62, i.e., the temperature detected by the temperature sensor 62, is output in the form of a voltage signal via two lead wires L2 to the analog processing circuit 63. The temperature sensor 62 may be any sensor that detects temperature.

2 and 3, the circuit board 65 constituting the analog processing circuit 63 and the second control unit 64 is fixed to the upper surface 45B of the coupling 45 by bolts (not shown) or the like. The circuit board 65 may be covered by a case or the like. The circuit board 65 has a through hole (or cutout; hereinafter, the same applies to this through hole) 65A through which the first shaft 43 passes. By having the first shaft 43 pass through the through hole 65A, it is possible to prevent the circuit board 65 from being unevenly distributed only in the area facing in one direction from the first shaft 43.

Returning to FIG. 1, the analog processing circuit 63 is configured to include analog circuits such as various filter circuits, amplifier circuits, and detection circuits such as a Wheatstone bridge circuit. The analog processing circuit 63 performs analog processing on each voltage signal output from the strain gauge 61 and the temperature sensor 62, and obtains the resistance value indicated by each voltage signal, that is, the strain detected by the strain gauge 61 or the temperature detected by the temperature sensor 62, and outputs it to the second control unit 64.

The second control unit 64 is connected to the first control unit 55 by wire, and operates by power supplied from the first control unit 55 by wire, and also supplies the necessary power to the analog processing circuit 63 by wire. The second control unit 64 performs analog/digital conversion of the strain and temperature (resistance value) from the analog processing circuit 63, and derives the valve element torque based on the strain and temperature as digital data after conversion. In other words, the second control unit 64 operates as a torque derivation unit that derives the valve element torque based on the strain detected by the strain gauge 61 and the temperature detected by the temperature sensor 62. The second control unit 64 derives the valve element torque, for example, by executing the torque derivation process shown in FIG. 4. The strain and temperature from the analog processing circuit 63 may be converted to digital data by an analog/digital conversion circuit outside the second control unit 64 and input to the first control unit 55.

In the torque derivation process shown in FIG. 4, the second control unit 64 first derives a torque value of the valve body torque based on the distortion (step S11). The second control unit 64 may derive the torque value by calculation based on the distortion, or may derive the torque value by referring to a table in which distortion and torque values are associated. Note that since the distortion is represented by a resistance value here, the second control unit 64 may derive the distortion value by calculation based on the resistance value or by referring to a table, etc., and derive the torque value based on the derived distortion.

Then, the second control unit 64 acquires a correction value for the torque value of the valve body torque derived in step S11 based on the temperature (step S12). The second control unit 64 stores in its own memory a correction table in which temperatures and correction values for torque values are associated with each other. This correction table is unique for each product, that is, for each strain gauge 61 to actuator 10, and is stored in the memory of the second control unit 64 when the actuator 10 is shipped from the factory. The second control unit 64 refers to the correction table based on the temperature and acquires a correction value corresponding to the temperature. The second control unit 64 may acquire the correction value by calculation based on the temperature. Note that the temperature is indicated by a resistance value here, so the second control unit 64 may derive the temperature by calculation based on the resistance value or by referring to a table, etc., and acquire the correction value based on the derived temperature.

Then, the second control unit 64 corrects the torque value derived in step S11 with the correction value obtained in step S12 (step S13), and outputs the corrected torque value as the torque value of the current valve body torque to the first control unit 55 (step S14).

As described above, the first control unit 55 shown in FIG. 1 performs a predetermined operation, for example, when the torque value of the valve body torque exceeds a predetermined threshold value. The threshold value is set as a value that indicates, for example, that an abnormality has occurred in the valve body 20 when the torque value exceeds this threshold value, or a value that the valve body 22 or the coupling 45, etc. may be damaged. Examples of abnormalities include an abnormality in which a foreign object collides with the valve body 22 and the valve body torque increases, and an abnormality in which a load is applied to the valve body 22 by a foreign object or the like when the valve body 22 tries to rotate with the rotation of the first shaft 43, and the valve body torque increases. Examples of cases in which the valve body 22 or the coupling 45, etc. may be damaged include, in addition to the presence of the foreign object, a case in which the flow of the fluid in the pipe 21A is greater than expected and a valve body torque greater than expected is applied to the rotating valve body 22. As the predetermined operation, the first control unit 55 outputs, for example, information to the signal processing circuit 51 to notify that the torque value of the valve body torque is higher than expected. The signal processing circuit 51 generates a signal indicating the information and transmits it to the higher-level device UD. Based on the information, the higher-level device UD notifies the user that the torque value of the valve disc torque indicates an abnormal value, thereby notifying the user of the abnormality of the actuator 10.

As described above, in the actuator 10 according to this embodiment, the strain gauge 61 is provided on the side surface 45E of the coupling 45 that connects the first shaft 43 and the second shaft 44 so that they rotate together, and detects the strain generated on the side surface 45E when the second shaft 44 rotates relative to the first shaft 43. This makes it unnecessary to provide a torque sensor separately from the coupling 45. Therefore, the total length of the actuator 10 in the vertical direction, which is the axial direction, is short. Furthermore, the strain gauge 61 can detect the torque that rotates the second shaft relative to the first shaft by detecting the above-mentioned strain. Thus, according to this embodiment, the total length of the actuator 10 in the axial direction (vertical direction) that can detect the torque that rotates the second shaft 44 relative to the first shaft 43 is suppressed from becoming long. In addition, according to this embodiment, both functions of connecting the first shaft 43 and the second shaft 44 and detecting the valve torque are integrated into the coupling 45, simplifying the device configuration, which allows for a significant reduction in the cost of valve torque measurement. It is also possible to detect the valve element torque from the current value of the motor 41A. However, because the actuator 10 of this embodiment amplifies the output torque of the motor 41A using the gears of the reducer 41B, there is a problem in that the control mechanism 50 of the actuator cannot distinguish whether the detected torque increase is due to an increase in the valve element torque of the valve element 22. According to this embodiment, this inconvenience is eliminated by using the strain gauge 61.

The coupling 45 also has an upper surface 45B on which the first hole 45A opens, into which the lower end 43A of the first shaft 43 is inserted, a lower surface 45D on which the second hole 45C opens, into which the upper end 44A of the second shaft 44 is inserted, and a side surface 45E connecting the upper surface 45B and the lower surface 45D. The strain gauge 61 is disposed on the side surface 45E of the coupling 45. With this configuration, in a coupling 45 having a conventional structure, the strain gauge 61 can be disposed on the side surface 45E, which is prone to distortion due to valve body torque, and the overall axial length of the actuator 10 is effectively prevented from becoming long.

Furthermore, the coupling 45 is cylindrical and has a communication hole 45G that communicates the first hole 45A and the second hole 45C. With this configuration, the strain gauge 61 can be provided in the coupling 45 of the conventional structure, and the overall axial length of the actuator 10 is more effectively prevented from increasing. Furthermore, the lower end 43A of the first shaft 43 and the upper end 44A of the second shaft 44 are spaced apart from each other within the communication hole 45G, and the strain gauge 61 is disposed between the lower end 43A of the first shaft 43 and the upper end 44A of the second shaft 44 in the vertical direction. With this configuration, the strain gauge 61 is disposed at a position on the side surface 45E of the coupling 45 that is relatively distorted when the valve body torque is applied to the second shaft 44, making it easier to detect distortion. This also makes it easier to detect the valve body torque.

Furthermore, a second control unit (torque derivation unit) 64 is provided that derives the valve body torque applied to the second shaft 44 due to the load on the valve body 22 based on the strain detected by the strain gauge 61, making it possible to monitor abnormalities, etc. within the valve body 20 based on the torque.

Furthermore, a temperature sensor 62 is provided to detect the temperature in the vicinity of the strain gauge 61 of the coupling 45, and the second control unit (torque derivation unit) 64 is configured to correct the valve body torque based on the temperature detected by the temperature sensor 62. The torque value of the valve body torque based on the strain detected by the strain gauge 61 may not be a true value due to the influence of thermal expansion of the coupling 45. As described above, the torque value of the valve body torque is corrected based on the temperature in the vicinity of the strain gauge 61 of the coupling 45, thereby obtaining a highly accurate torque value of the valve body torque. Note that the resistance value of the resistor or semiconductor of the strain gauge 61 may change due to heat, and as a result, the strain (particularly the strain indicated by the resistance value) or torque value detected by the strain gauge 61 may not be a true value. For this reason, the second control unit 64 may correct the value of the strain based on the temperature when deriving the torque value. The object and method of the temperature-based correction performed by the second control unit 64 are arbitrary. The second control unit 64 may be configured to derive the valve element torque based on, for example, the strain detected by the strain gauge 61 and the temperature detected by the temperature sensor 62. This allows for a highly accurate valve element torque to be obtained.

Furthermore, the circuit board 65 constituting the second control unit (torque derivation unit) 64 is arranged outside the housing 31 that houses the drive source 41 of the actuator 10 and the first control unit 55, etc. As a result, when the second control unit 64 breaks down, it is only necessary to replace the circuit board 65, so that the trouble of opening the housing 31 can be eliminated. Here, consider a case where the second control unit 64 stores the correction table as described above, and the correction table has different contents for each strain gauge 61. In this case, if either the strain gauge 61 or the second control unit 64 breaks down at the site where the actuator 10 is actually used, it becomes necessary to replace both the strain gauge 61 and the second control unit 64. Even in such a case, the second control unit 64 can be replaced at the site by simply replacing the circuit board 65 arranged outside the housing 31, so that the replacement work of the second control unit 64 is easy. Furthermore, since the circuit board 65 and the strain gauge 61 are gathered on the coupling 45, the replacement work of both the circuit board 65 and the strain gauge 61 is easy. These advantages are especially evident when compared to an embodiment in which torque derivation and correction are performed by the first control unit 55. In the above embodiment, replacing the strain gauge 61 requires updating the correction table stored in the first control unit 55 or replacing the first control unit 55, which requires opening the housing 31 and is time-consuming.

In addition, in this embodiment, the circuit board 65 constituting the second control unit (torque derivation unit) 64 has a through hole (or cutout) 65A through which the first shaft 43 passes, and is fixed to the coupling 45. The circuit board 65 may be fixed to the lower surface 45D of the coupling 45. In this case, the second shaft 44 passes through the through hole 65A. By passing the first shaft 43 or the second shaft 44 through the through hole 65A, it is possible to prevent the circuit board 65 from being unevenly distributed only in the area facing one direction from the first shaft 43 or the second shaft 44. This reduces the eccentricity of the rotating coupling 45. Furthermore, in this embodiment, since the strain gauge 61 and the circuit board 65 are provided on the coupling 45, a configuration for torque detection can be easily added later. Instead of or in addition to transmitting the derived torque to the first control unit 55, the second control unit 64 may compare the torque with a predetermined threshold value or the like by itself. In this case, when the torque exceeds a threshold value, the second control unit 64 may output a notification to that effect using a speaker, an indicator light, or any combination of two or more of these.

Furthermore, the first control unit 55 communicates with the second control unit (torque derivation unit) 64 via a wired connection, and supplies power to the second control unit 64 via a wired connection, thereby ensuring high accuracy of communication and power supply.

The actuator 10 according to this embodiment is configured as a flow control valve. It is required to measure the valve torque of a flow control valve inexpensively. Commercially available torque sensors are used in the arms of robots and the like, and are required to measure axial torque at high speed, multiple rotations, high torque, and high accuracy, and are usually expensive with a complex structure. For this reason, the torque sensor is not suitable for the flow control valve. On the other hand, the torque measurement in this embodiment is performed, for example, when the valve body 22 is rotated about 90 degrees over 50 to 60 seconds, and is further intended to detect whether there is an abnormality in the valve body 20. For this reason, measurement accuracy is not required to be high. For this reason, the configuration for torque detection using the strain gauge 61 can be simplified.

The present invention is not limited to the above-described embodiment. Various modifications may be made to the above-described embodiment. Below, modifications of the above-described embodiment are described, and at least some of the modifications may be combined with each other.

The positions of the analog processing circuit 63 and the second control unit 64 of the torque detection mechanism 60 can be changed as appropriate. For example, as shown in FIG. 5, the analog processing circuit 63 and the second control unit 64 may be arranged inside the housing 31. In FIG. 5, the drive mechanism 40 and the like are omitted (the same applies to FIG. 6 and the following). The first control unit 55 and the second control unit 64 may be configured by a common computer such as a microcomputer. In other words, one computer may operate as the first control unit 55 and the second control unit 64. With this configuration, it is not necessary to arrange the circuit board 65 and the like outside the housing 31, and the device configuration of the actuator 10 is simplified. The analog processing circuit 63 may be configured by the circuit board 65 on the coupling, and only the second control unit 64 may be arranged inside the housing 31. In this case, the first control unit 55 may operate as the second control unit 64.

The first control unit 55 and the second control unit 64 may communicate wirelessly and supply power wirelessly. For example, as shown in FIG. 6, in addition to the first control unit 55, a wireless power supply unit 59A that transmits power wirelessly and a wireless communication unit 59B that transmits and receives information such as the torque value wirelessly are provided inside the housing 31. Also, a wireless power receiving unit 69A that receives power from the wireless power supply unit 59A and a wireless communication unit 69B that transmits and receives information such as the torque value wirelessly are provided on the coupling 45 or the circuit board 65. The wireless power supply unit 59A and the wireless power receiving unit 69A are composed of various circuits that supply power wirelessly. The wireless communication units 59B and 69B are each composed of an antenna and a modulation or demodulation circuit. By performing communication and power supply wirelessly, it is not necessary to lay wires connecting the first control unit 55 and the second control unit 64. This configuration is advantageous when applying the present invention to any device in which the first and second shafts rotate multiple times, such as a robot in which the first and second shafts rotate 360 degrees or more, as described below. This prevents problems such as tangling of the wiring caused by the rotation of the first shaft, etc.

The first control unit 55 and the second control unit 64 may perform at least one of the communication and power supply wirelessly and the other wired. For example, as shown in FIG. 7, power may be supplied wired. If power is supplied wirelessly, the electric field strength may increase depending on the environmental conditions, which may cause adverse effects such as crosstalk on the radio waves used for wireless communication. By supplying power wired as described above, crosstalk of the radio waves used for wireless communication is prevented.

The shape of the components that make up the actuator 10 can be changed as appropriate. For example, the shape of the coupling 45 may be a polygonal tube. The first hole 45A and the second hole 45C of the coupling 45 do not have to be connected to each other.

The present invention can also be applied to actuators other than flow control valves. For example, the present invention may be applied to an air volume adjustment damper having a valve body that adjusts the volume of air. The present invention can be applied to actuators having a first shaft and a second shaft connected by a coupling in general. The first shaft may be, for example, a drive shaft that rotates by directly or indirectly transmitting driving force from a drive source such as a motor or an engine. The second shaft may be, for example, a shaft that is integral with the first shaft, rotates following the first shaft, and rotates a predetermined rotating object (such as a valve body or a robot arm). The present invention can be applied to actuators of large valves, various dampers, and all devices in which two or more shafts are connected by a coupling, such as robots.

Although the present invention has been described above with reference to the embodiments and modifications, the present invention is not limited to the above-mentioned embodiments and modifications. For example, the present invention includes various modifications to the above-mentioned embodiments and modifications that can be understood by a person skilled in the art within the scope of the technical concept of the present invention. The configurations listed in the above-mentioned embodiments and modifications can be combined as appropriate within a range that does not cause inconsistencies.

10...actuator, 20...valve body, 22...valve body, 30...drive device, 31...housing, 40...drive mechanism, 41...drive source, 41A...motor, 43...first shaft, 44...second shaft, 45...coupling, 45A...first hole, 45B...upper surface, 45C...second hole, 45D...lower surface, 45E...side surface, 45G...communication hole, 50...control mechanism, 55...first control unit, wireless power supply unit...59A, wireless communication unit...59B, 60...torque detection mechanism, 61...strain gauge, 62...temperature sensor, 64...second control unit, wireless power receiving unit...69A, wireless communication unit...69B.

Claims (6)

An actuator configured as a flow control valve,
A driving source;
A control unit that controls the driving source;
a housing that houses the driving source and the control unit;
A first shaft which is a drive shaft that is driven to rotate by the drive source ;
A second shaft is a driven shaft that is coaxial with the first shaft and rotates following the rotation of the first shaft to rotate a valve body that controls the flow rate of a fluid flowing through a pipe ;
a coupling that connects the first shaft and the second shaft so that the first shaft and the second shaft rotate together;
a strain gauge disposed on a surface of the coupling and configured to detect strain on the surface when the second shaft rotates relative to the first shaft;
a torque deriving unit configured to derive a valve element torque applied to the valve element based on the strain detected by the strain gauge,
the torque derivation unit is configured by a circuit board disposed outside the housing,
The circuit board has a through hole or a notch through which the first shaft or the second shaft passes, and is fixed to the coupling.
Actuator. the coupling includes a first surface on which a first hole into which one end of the first shaft is inserted opens, a second surface on the opposite side to the first surface on which a second hole into which one end of the second shaft is inserted opens, and a third surface connecting the first surface and the second surface,
the strain gauge is disposed on the third surface;
The actuator of claim 1 . the coupling has a cylindrical shape and a communication hole through which the first hole and the second hole communicate with each other,
the one end of the first shaft and the one end of the second shaft are spaced apart from each other within the communication hole,
The strain gauge is disposed between the one end of the first shaft and the one end of the second shaft in an axial direction of the first shaft.
The actuator according to claim 2 . a temperature sensor configured to detect a temperature in a vicinity of the strain gauge of the coupling;
The torque derivation unit is configured to derive the torque based on the strain and the temperature detected by the temperature sensor.
The actuator of claim 1 . The control unit is configured to communicate with the torque derivation unit via a wire and to supply power to the torque derivation unit via a wire.
The actuator of claim 1 . The control unit is configured to wirelessly communicate with the torque derivation unit and wirelessly supply power to the torque derivation unit.
2. The actuator of claim 1 .

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