JP6802104B2 - Rotation control device - Google Patents

Description

The present invention relates to a rotation control device that controls the rotation of an operation target shaft, for example, a rotation control device having a valve shaft of a control valve as an operation target shaft.

Generally, a rotation control device that controls the rotation of an operation target shaft such as a valve shaft detects a mechanical displacement of the operation target shaft in the rotation direction by a position sensor, and determines the operation amount of the shaft based on the detection result. There is. For example, in an electric actuator (actuator) that operates a valve shaft of a rotary type control valve such as a ball valve, a potentiometer composed of a variable resistor is used as a position sensor, and the direction of rotation of the valve shaft detected by the potentiometer The valve shaft is controlled based on the amount of mechanical displacement (see Patent Document 1).

In addition, as a position sensor for measuring the amount of mechanical displacement in the rotation direction of the shaft, in addition to a contact type position sensor represented by a potentiometer, a position in the rotation direction of the shaft to be measured like a rotary encoder. There is a non-contact type position sensor that detects non-contact. Further, the non-contact type position sensor outputs an absolute position sensor that outputs a signal corresponding to the angular position of the detection target axis and a signal corresponding to the rotation angle of the detection target axis, that is, the amount of change in the angular position. There is a relative position sensor. For example, as a non-contact type absolute position sensor, an absolute rotary encoder that outputs a code signal corresponding to the absolute angular position of the detection target axis is used, and as a non-contact type relative position sensor, a detection target. Incremental rotary encoders that output pulses corresponding to the rotation angle of the shaft are known (see Patent Document 2).

Japanese Unexamined Patent Publication No. 2011-074935 Japanese Unexamined Patent Publication No. 2010-286444

In general, a potentiometer is a sensor that outputs a change in resistance value by mechanically operating a slider, and therefore tends to have low durability and a short product life. In addition, when an absolute type rotary encoder as an absolute non-contact position sensor is used instead of a potentiometer, the unit cost of parts is generally high, and a separate battery for driving the absolute type rotary encoder is required. Therefore, the product cost increases.

Therefore, the inventor of the present application uses a non-contact relative position sensor such as a rotary encoder and an ON / OFF sensor that outputs a detection signal when the operation target axis reaches a predetermined position instead of the potentiometer. We proposed a new rotation control device (Japanese Patent Application No. 2017-034014). In this rotation control device, for example, as shown in FIG. 18, the ON / OFF sensor is provided on the main surface 20a of the printed circuit board 20 on which the IC chip 30 is provided near the operation target axis 200 and performs various arithmetic processes. The electrode 21a is arranged, and the short plate 201 connected to the operation target shaft 200 is brought into contact with any of the electrodes 21a to detect the absolute position of the operation target shaft although it is discontinuous. Hereinafter, a position sensor that detects the absolute position of the operation target axis while being discontinuous by using such an ON / OFF sensor may be referred to as a “discontinuous absolute position sensor”.

However, in such a configuration, if the short plate 201 is not brought into contact with the printed circuit board 20, it is necessary to finely adjust the distance between the short plate and the printed circuit board 20, which not only causes an increase in cost but also realizes the realization. It's not easy. In addition, there is a problem in the reliability of contact resistance due to the secular change of the springiness of the short plate. On the contrary, if the short plate 201 slides the main surface 20a of the printed circuit board 20, the printed circuit board 20 may be adversely affected, which causes problems of durability and product life as in the potentiometer.

The present invention has been made in view of the above problems, and an object of the present invention is rotation control for measuring the position of the operation target axis in the rotation direction by a non-contact relative position sensor and an ON / OFF sensor. The purpose is to improve the durability and reliability of the device while realizing it at a lower cost.

The rotation control device (100) for controlling the rotation of the operation target shaft (200) according to the present invention is operated by a relative position sensor (1) that non-contactly detects mechanical displacement of the operation target shaft in the rotation direction. At least one predetermined intermediate position (Pa,) excluding the first position and the second position in the rotatable range (SR) from the first position (Pc) to the second position (Po) in the rotation direction of the target axis. The ON / OFF sensor (2_1 to 2_n) that outputs a detection signal when the axis to be operated reaches Pm, Pb) and the mechanical displacement detected by the relative position sensor after the detection signal is output. The absolute position in the rotation direction of the operation target axis is calculated based on the integrated value (RP) and the reference value (AP) indicating a predetermined intermediate position corresponding to the ON / OFF sensor that outputs the detection signal. The operation target axis is based on the information of the position calculation unit (3), the target position (SP) in the rotation direction of the operation target axis, and the absolute position (PV) of the operation target axis calculated by the position calculation unit. Based on the operation amount calculation unit (4) that calculates the operation amount (MV) of, and the operation amount calculated by the operation amount calculation unit, it is possible to rotate from the first position to the second position in the rotation direction of the operation target axis. The operation unit (5) for operating the operation target axis is provided within the above range, and the ON / OFF sensor is provided around the operation target axis and has a main surface (20a, 20b) orthogonal to the axis of the operation target axis. The substrate (20) to be held, at least one electrode (21a, 21b) arranged on the main surface of the substrate, and one end fixed to the operation target shaft, extending in the radial direction of the operation target shaft, and the operation target shaft. A contactor (201a, 201b) in which a part of the other end contacts one of the electrodes when is in a predetermined intermediate position, and a detection circuit that outputs a detection signal when the contactor contacts one of the electrodes (201a, 201b). 23_i) and cam members (24a, 24b) arranged on the main surface of the substrate and moving the other end of the contactor in a direction away from the main surface when the operation target axis is not at a predetermined intermediate position. Be prepared.

In the rotation control device, the electrodes (21a, 21b) are arranged at positions corresponding to predetermined intermediate positions on the main surface, and the cam members (24a, 24b) have a circumference about the axis of the operation target axis. It may be arranged along (C2) so that the height from the main surface decreases as it approaches a position corresponding to a predetermined intermediate position on the main surface along the circumference.

In the rotation control device, the electrodes (21a, 21b) and the cam members (24a, 24b) have a first circumference (C1) having different radii about the axis of the operation target axis on the main surface, respectively. The ends of the two cam members that are arranged along the second circumference (C2) and are adjacent to each other on the main surface may be separated from each other on the main surface.

In the rotation control device, the electrodes (21a, 21b) and the cam member (24a, 24b) are arranged on the same circumference (C1) centered on the axis of the operation target axis on the main surface, and the cam member. (24a, 24b) are each formed of an insulating material, and the opposite ends of the two adjacent cam members on the main surface of the cam member each cover a part of the electrode (21). They may be separated from each other on the electrodes.

In the rotation control device, the contacts (201a, 201b) are elastically deformable plate-shaped members, and the width of the portion that comes into contact with the electrodes when the operation target axis is at a predetermined intermediate position is on the main surface. It may be narrower than the distance between the opposite ends of the two adjacent cam members.

In the rotation control device, the substrate has a first main surface (20a) and a second main surface (20b) opposite to the first main surface as main surfaces, and the electrodes are on the first main surface. The contact is composed of at least one first electrode (21a) arranged on the second main surface and at least one second electrode (21b) arranged on the second main surface, and one end of the contactor is fixed to the operation target shaft. A first contact (201a) extending in the radial direction of the operation target shaft, and a part of the other end side contacting one of the first electrodes when the operation target shaft is in a predetermined intermediate position, and a first While being electrically connected to the contactor, one end is fixed to the operation target shaft, extends in the radial direction of the operation target shaft, and when the operation target shaft is in a predetermined intermediate position, a part of the other end side is Composed of a second contact (201b) that contacts one of the second electrodes, the cam member is placed on the first main surface of the substrate and first contacts when the operating axis is not in a predetermined intermediate position. A plurality of first cam members (24a) for moving the other end of the child in a direction away from the main surface, and a second cam member (24a) arranged on the second main surface of the substrate and when the operation target axis is not in a predetermined intermediate position. The detection circuit includes a plurality of second cam members (24b) that move the other end of the contact in a direction away from the main surface, and a part of the other end side of the first contact contacts the first electrode. In addition, a detection signal may be output when a part of the other end side of the second contactor comes into contact with the second electrode.

The rotation control device further includes a reversal count counting unit (6) that counts the number of times the rotation direction of the operation target axis has been reversed, and the operation amount calculation unit (4A) counts the number of reversals without outputting a detection signal. When the value counted by the unit exceeds a predetermined threshold value, the operation amount for moving the operation target axis to any one of the first position, the second position, and the predetermined intermediate position is calculated, and the operation unit is calculated. In (5), the operation target axis may be operated based on the operation amount calculated by the operation amount calculation unit.

The rotation control device further includes an absolute value integrating unit (7) that integrates the absolute value of the mechanical displacement of the operation target shaft in the rotation direction, and the operation amount calculation unit (4B) does not output a detection signal. Calculates the amount of operation to move the operation target axis to any one of the first position, the second position, and the predetermined intermediate position when the value integrated by the absolute value integrating unit exceeds a predetermined threshold value. , The operation unit (5) may operate the operation target axis based on the operation amount calculated by the operation amount calculation unit.

The rotation control device further includes a timer (8) that integrates the elapsed time without outputting the detection signal, and the operation amount calculation unit (4C) determines the elapsed time without outputting the detection signal. When the threshold value of is exceeded, the operation amount for moving the operation target axis to any one of the first position, the second position and the predetermined intermediate position is calculated, and the operation unit (5) calculates the operation amount. The operation target axis may be operated based on the operation amount calculated by the unit.

The rotation control device further includes a start count counting unit (9) that counts the number of times the operation target axis has started to move, and the operation amount calculation unit (4D) counts by the start count count unit without outputting a detection signal. When the set value exceeds a predetermined threshold value, the operation amount for moving the operation target axis to any one of the first position, the second position, and the predetermined intermediate position is calculated, and the operation unit ( In 5), the operation target axis may be operated based on the operation amount calculated by the operation amount calculation unit.

In the rotation control device, the position calculation unit (3) includes a reference value update unit (32) that resets the integrated value of the mechanical displacement detected by the relative position sensor when the detection signal is output. May be good.

In the above description, as an example, reference numerals on drawings corresponding to the components of the invention are described in parentheses.

As described above, according to the present invention, a rotation control device that measures the position of the operation target axis in the rotation direction by a non-contact relative position sensor and an ON / OFF sensor can be realized at a lower cost. , Its durability and reliability can be improved.

FIG. 1 is a diagram showing a configuration of a rotation control device according to the first embodiment. FIG. 2 is a diagram illustrating the concept of a discontinuous absolute position sensor. FIG. 3A is a diagram showing an example of the configuration of a discontinuous absolute position sensor. FIG. 3B is a diagram showing an example of the configuration of a discontinuous absolute position sensor. FIG. 3C is a diagram showing an example of the configuration of a discontinuous absolute position sensor. FIG. 3D is a diagram showing an example of the configuration of a discontinuous absolute position sensor. FIG. 3E is a diagram illustrating the relationship between the electrode and the cam member in an example of the configuration of the discontinuous absolute position sensor. FIG. 4 is a flow chart illustrating the operation of the rotation control device according to the first embodiment in the origin return operation mode. FIG. 5 is a flow chart illustrating the operation of the rotation control device according to the first embodiment in the normal operation mode. FIG. 6A is a diagram showing another configuration example of the discontinuous absolute position sensor. FIG. 6B is a diagram illustrating the relationship between the electrode and the cam member in another configuration example of the discontinuous absolute position sensor. FIG. 7A is a diagram showing a modified example of a discontinuous absolute position sensor. FIG. 7B is a diagram illustrating a relationship between an electrode and a cam member in a modified example of a discontinuous absolute position sensor. FIG. 7C is a diagram showing a modified example of the discontinuous absolute position sensor. FIG. 7D is a diagram showing a modified example of the discontinuous absolute position sensor. FIG. 8 is a diagram showing the configuration of the rotation control device according to the second embodiment. FIG. 9A is a flow chart illustrating the operation of the rotation control device according to the second embodiment. FIG. 9B is a flow chart illustrating the operation of the rotation control device according to the second embodiment. FIG. 10 is a diagram showing the configuration of the rotation control device according to the third embodiment. FIG. 11A is a flow chart illustrating the operation of the rotation control device according to the third embodiment. FIG. 11B is a flow chart illustrating the operation of the rotation control device according to the third embodiment. FIG. 12 is a diagram showing the configuration of the rotation control device according to the fourth embodiment. FIG. 13A is a flow chart illustrating the operation of the rotation control device according to the fourth embodiment. FIG. 13B is a flow chart illustrating the operation of the rotation control device according to the fourth embodiment. FIG. 14 is a diagram showing the configuration of the rotation control device according to the fifth embodiment. FIG. 15A is a flow chart illustrating the operation of the rotation control device according to the fifth embodiment. FIG. 15B is a flow chart illustrating the operation of the rotation control device according to the fifth embodiment. FIG. 16A is a diagram showing another arrangement example of the discontinuous absolute position sensor. FIG. 16B is a diagram showing another configuration example of the discontinuous absolute position sensor. FIG. 17A is a diagram showing another arrangement example of the discontinuous absolute position sensor. FIG. 17B is a diagram showing another configuration example of the discontinuous absolute position sensor. FIG. 18 is a diagram illustrating an example of the configuration of the discontinuous absolute position sensor in the prior application.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same reference reference numerals will be given to the components common to each embodiment, and the repeated description will be omitted.

<Embodiment 1>
≪Rotation control device configuration≫
FIG. 1 is a diagram showing a configuration of a rotation control device according to the first embodiment.
The rotation control device 100 shown in the figure is, for example, an electric actuator that controls the rotation of the valve shaft of a rotary type control valve such as a ball valve used for process control of flow rate in a plant or the like.

Specifically, the rotation control device 100 includes a target value (set value) SP of the valve opening of the control valve given by a higher-level device (not shown) and an actually measured value of the valve opening of the control valve (hereinafter, “actual opening”). It is also referred to as "degree".) An operator that calculates the deviation ΔP from PV and drives the valve shaft 200 so that the deviation ΔP becomes 0, thereby controlling the valve opening degree of the control valve to be the target value. Is.

Hereinafter, a specific configuration of the rotation control device 100 will be described.
As shown in FIG. 1, the rotation control device 100 includes a relative position sensor 1, a plurality of ON / OFF sensors 2_1 to 2_n (n is an integer of 2 or more), a position calculation unit 3, an operation amount calculation unit 4, and an operation amount calculation unit 4. The operation unit 5 is provided. The plurality of ON / OFF sensors 2_1 to 2_n form a discontinuous absolute position sensor.

These components are housed inside a housing made of, for example, a metal material. In addition to the above-mentioned functional unit, the rotation control device 100 transmits / receives data to / from a display unit (for example, a liquid crystal display) for presenting various information such as the valve opening degree of the control valve to the user and an external device. A communication circuit or the like for performing the above may be provided.

First, a discontinuous absolute position sensor including a relative position sensor 1 and an ON / OFF sensor 2_1 to 2_n for measuring the actual opening degree of the control valve, that is, the position of the valve shaft 200 in the rotational direction will be described.

The relative position sensor 1 is a functional unit that non-contactly detects the mechanical displacement Md of the valve shaft 200 as the operation target shaft of the rotation control device 100 in the rotation direction. As the relative position sensor 1, an incremental rotary encoder that outputs a pulse corresponding to the rotation angle of the detection target axis (valve shaft 200) can be exemplified. In the present embodiment, the relative position sensor 1 will be described as an incremental rotary encoder.

On the other hand, the discontinuous absolute position sensor includes the ON / OFF sensors 2_1 to 2_n, and corresponds to the predetermined position when the valve shaft 200, which is the operation target axis, reaches a predetermined position in the rotation direction. Each of the provided ON / OFF sensors 2_1 to 2_n outputs detection signals P1 to Pn, respectively. The ON / OFF sensors 2_1 to 2_n may be any component capable of outputting an electric signal indicating that the valve shaft 200 has reached a specific position in the rotation direction. Specifically, for example, a limit switch can be used as the ON / OFF sensor 2_1 to 2_n. Here, the electric signal may be any signal indicating that the valve shaft 200 has reached a specific position in the rotation direction, and is, for example, an on / off signal (a signal indicating a state, for example, a digital signal).

The arrangement of the ON / OFF sensors 2_1 to 2_n will be described with reference to FIG. FIG. 2 shows an arrangement example of the ON / OFF sensors 2_1 to 2_5 when n = 5.

As shown in FIG. 2, the ON / OFF sensors 2_1 to 2_5 are provided corresponding to a plurality of different positions within the rotatable range SR of the valve shaft 200, and the valve shaft 200 reaches the corresponding position. When this is done, the detection signals P1 to Pn are output respectively.

Here, the rotatable range SR is a rotatable range in the rotation direction of the valve shaft 200, and is, for example, a second from the fully closed position Pc where the valve opening degree as the first position in the rotation direction is 0%. The range up to the fully open position Po where the valve opening as a position becomes 100% is shown.

In the rotation control device 100, the ON / OFF sensors 2-1 to 2_5 are provided corresponding to any position in the range where the valve opening degree is from 0% to 100%. For example, in the case of the arrangement example shown in FIG. 2, the ON / OFF sensor 2_1 is provided corresponding to the fully closed position Pc in which the valve opening is 0%, and the ON / OFF sensor 2_2 has a valve opening of 20%. The ON / OFF sensor 2_3 is provided corresponding to the position Pa corresponding to the position Pa, the ON / OFF sensor 2_3 is provided corresponding to the position Pm at which the valve opening is 50%, and the ON / OFF sensor 2_4 is provided at the valve opening of 70%. The ON / OFF sensor 2_5 is provided corresponding to the position Pb, and is provided corresponding to the fully open position Po at which the valve opening degree is 100%.
In the valve shaft 200, the position Pa where the valve opening is 20% and the valve opening is 50, excluding the fully closed position Pc where the valve opening is 0% and the fully open position Po where the valve opening is 100%. The position Pm at% and the position Pb at which the valve opening degree is 70% correspond to the “predetermined intermediate position” in the present invention, respectively.

In the case of the arrangement example shown in FIG. 2, the ON / OFF sensor 2_1 outputs the detection signal P1 when the valve shaft 200 reaches the fully closed position Pc. The ON / OFF sensor 2_2 outputs a detection signal P2 when the valve shaft 200 reaches the position Pa (valve opening: 20%). The ON / OFF sensor 2_3 outputs a detection signal P3 when the valve shaft 200 reaches the position Pm (valve opening: 50%). The ON / OFF sensor 2_4 outputs a detection signal P4 when the valve shaft 200 reaches the position Pb (valve opening: 70%). The ON / OFF sensor 2_5 outputs a detection signal P5 when the valve shaft 200 reaches the fully open position Po (valve opening: 100%).

Next, the specific structure of the ON / OFF sensors 2_1 to 2_n will be described.
The ON / OFF sensors 2_1 to 2_n are provided around the valve shaft 200, and have a printed circuit board 20 having a first main surface 20a and a second main surface 20b orthogonal to the axis of the valve shaft 200, and a first printed circuit board. A plurality of first electrodes 21a and second electrodes 21b arranged on the main surface 20a and the second main surface 20b, a short plate 201 fixed to the side surface of the valve shaft 200, and a first contactor of the short plate 201. The detection circuit 23_i that outputs a detection signal Pi when the 201a and the second contactor 201b come into contact with one of the plurality of first electrodes 21a and the second electrode 21b, respectively, and the first main surface 20a of the printed circuit board 20 are arranged. A plurality of first cam members 24a and a plurality of second cam members 24b arranged on the second main surface 20b are provided.

Hereinafter, the first main surface 20a and the second main surface 20b of the printed circuit board 20 may be collectively referred to as "main surfaces 20a and 20b". Further, the first electrode 21a and the second electrode 21b may be collectively referred to as "electrodes 21a and 21b". Further, the first contactor 201a and the second contactor 201b of the short plate 201 may be collectively referred to as "contactors 201a, 201b". Further, the first cam member 20a and the second cam member 20b may be collectively referred to as "cam members 20a, 20b".

3A to 3E are diagrams showing an example of a specific structure of the ON / OFF sensors 2_1 to 2_n. Here, the case where n = 5 is illustrated.

Here, in FIGS. 3A and 3B, the valve shaft 200 is in the fully closed position Pc, the position Pa (valve opening: 20%), the position Pm (valve opening: 50%), and the position Pb (valve opening: 20%), respectively. It is a plan view and a cross-sectional view schematically showing the structure of the ON / OFF sensor 2_1 to 2_n in a state where it reaches either 70%) or the fully open position Po (valve opening: 100%). 3C and 3D are plan views and cross-sectional views schematically showing the structure of the ON / OFF sensors 2_1 to 2_n when the valve shaft 200 does not reach any of the above-mentioned predetermined positions, respectively. is there. Further, FIG. 3E is a side view schematically showing the structure of the ON / OFF sensors 2_1 to 2_n.

In this example, the individual ON / OFF sensors 2_i (1 ≦ i ≦ n) have resistors R and electrodes 21a on a printed circuit board 20 provided around the valve shaft 200, as shown in FIGS. 3A-3E. This can be achieved by arranging 21b and providing a short plate 201 on the valve shaft 200.

Specifically, the first electrode 21a is formed on the first main surface 20a of the printed circuit board 20, and the resistor R is connected between the first electrode 21a and the power supply line Vcc to which the power supply voltage is supplied. Further, the second electrode 21b is formed on the second main surface 20b of the printed circuit board 20, and the second electrode 21b is connected to the ground line GND to which the ground voltage is supplied. The plurality of electrodes 21a and 21b formed on the two main surfaces 20a and 20b of the printed circuit board 20 are arranged along the circumference C1 centered on the axis of the valve shaft 200, respectively. Here, the resistor R may be arranged, for example, on the first main surface 20a of the printed circuit board 20. Further, the power supply line Vcc may be formed on the first main surface 20a of the printed circuit board 20, for example, and the ground line GND may be formed on the second main surface 20b of the printed circuit board 20, for example.

On the first main surface 20a of the printed circuit board 20, an IC chip 30 including a program processing device such as a microcontroller or a CPU that functions as a position calculation unit 3 and an operation amount calculation unit 4 described later is arranged. Here, the node na to which the resistor R and the electrode 21a described above are connected is connected to any one input terminal of the IC chip 30.

The valve shaft 200 is inserted through a through hole 20c provided in the printed circuit board 20. The axis of the valve shaft 200 and the main surfaces 20a and 20b of the printed circuit board 20 are orthogonal to each other. A short plate 201 is joined to the outer peripheral surface of the valve shaft 200.

As shown in FIGS. 3B and 3D, the short plate 201 is formed, for example, in a side view “U” shape. The short plate 201 may be formed in a "U" shape in a side view by bending a strip-shaped plate member made of a metal such as brass or stainless steel, for example. By fixing such a short plate 201 to the side surface of the valve shaft 200 with a screw or the like, one end of the short plate 201 is fixed to the valve shaft 200 and the first contact extends in the radial direction of the valve shaft 200. The child 201a is electrically connected to the first contactor 201a, and one end thereof is fixed to the valve shaft 200 to provide a second contactor 201b extending in the radial direction of the valve shaft 200. The first contactor 201a and the second contactor 201b are both elastically deformable plate-shaped members. The printed circuit board 20 is arranged between the pair of contacts 201a and 201b. In this state, the contacts 201a'and 201b' of these contacts 201a and 201b are urged in the directions of the two main surfaces 20a and 20b on the front and back sides of the printed circuit board 20, respectively. Therefore, the short plate 201 fixed to the valve shaft 200 rotates together with the valve shaft 200 with the pair of opposing contacts 201a and 201b sandwiching the printed circuit board 20.

The valve shaft 200 is in any of the fully closed position Pc, the position Pa where the valve opening is 20%, the position Pm where the valve opening is 50%, the position Pb where the valve opening is 70%, and the fully open position Po. When the position is reached, the contacts 201a and 201b of the short plate 201 come into contact with the electrodes 21a and 21b arranged at the positions corresponding to these predetermined positions. For example, as shown in FIG. 3A, when the valve shaft 200 rotates and the short plate 201 reaches the position of the ON / OFF sensor 2_3, the contact 201a'of the short plate 201 becomes the electrode 21a of the ON / OFF sensor 2_3. At the same time, the contact 201b'of the short plate 201 comes into contact with the electrode 21b of the ON / OFF sensor 2_3. At this time, a current path is formed from the power supply line Vcc to the ground line GND via the resistor R, the electrode 21a, the short plate 201, and the electrode 21b, and the potential of the node na becomes 0V (ground potential).

On the other hand, as shown in FIG. 3C, when the short plate 201 is between the ON / OFF sensor 2_1 and the ON / OFF sensor 2_2, that is, when the valve shaft 200 is not in a predetermined intermediate position, the short plate 201 The contacts 201a'and 201b' are in a state where they do not come into contact with the electrodes 21a and 21b of any of the ON / OFF sensors 2_1 to 2_5. As a result, the potential of the node na of each ON / OFF sensor 2_1 to 2_5 becomes Vcc (power supply voltage).

In this way, by inputting the voltage change of the node na of each ON / OFF sensor 2_1 to 2_5 as a detection signal to the IC chip 30, it is possible to detect that the valve shaft 200 has reached a predetermined position in the rotation direction. It will be possible. Therefore, the resistor R whose one end is connected to the power supply line Vcc, the electrode 21a connected to the other end of the resistor R, and the electrode 21b connected to the ground line GND are the contacts 201a and 201b of the short plate 201. A detection circuit that outputs a detection signal Pi when a part of the other end side comes into contact with one of the plurality of electrodes 21a and 21b is configured.

Further, in the present embodiment, the ON / OFF sensor includes a cam member 24a arranged on the first main surface 20a of the printed circuit board 20 and a cam member 24b arranged on the second main surface 20b. There is. As shown in FIGS. 3A and 3C, these cam members 24a and 24b are arranged on the two main surfaces 20a and 20b of the printed circuit board 20 along the circumference C2 centered on the axis of the valve shaft 200, respectively. Has been done.

The cam members 24a and 24b are made of a material such as plastic, and as they approach a position corresponding to a predetermined intermediate position on the main surface along the circumference C2, that is, a position where the electrodes 21a and 21b are arranged. It has a shape in which the height from the main surface is low. The opposing ends of two adjacent cam members on the two main surfaces 20a and 20b are separated from each other.
In order to fix these cam members 24a and 24b to the printed circuit board 20 with an adhesive, an adhesive or screws may be used. Instead of mounting the cam members 24a and 24b on the printed circuit board 20, the cam members 24a and 24b may be formed on a structure such as a resin case (not shown).

FIG. 3D shows a discontinuous absolute position when the valve shaft 200 is not in a predetermined position, that is, at any of the fully closed position Pc, position Pa, position Pm, position Pb, and fully open position Po shown in FIG. It is a figure explaining the state of a sensor. As shown in FIG. 3D, when the valve shaft 200 is not in any of the predetermined positions, the contacts 201a and 201b of the short plate 201 are cams provided on both main surfaces 20a and 20b of the printed circuit board 20, respectively. It comes into contact with the members 24a and 24b, and the other end side of the contacts 201a and 201b moves in a direction away from both main surfaces 20a and 20b of the printed circuit board 20. Therefore, in this case, the contacts 201a'and 201b' of the contacts 201a and 201b do not come into contact with the main surfaces 20a and 20b of the printed circuit board 20.
On the other hand, when the valve shaft 200 is at any of the predetermined positions, the contacts 201a and 201b of the short plate 201 come into contact with the electrodes 21a and 21b, as shown in FIG. 3B.

Next, the position calculation unit 3, the operation amount calculation unit 4, and the operation unit 5 will be described.

The position calculation unit 3 is a functional unit that calculates the absolute position of the valve shaft 200. The position calculation unit 3 includes the integrated value of the mechanical displacement Md detected by the relative position sensor 1 after the detection signals P1 to Pn of the ON / OFF sensors 2_1 to 2_n are output, and the detection signals P1 to Pn. The absolute position in the rotation direction of the operation target axis is calculated based on the reference value indicating the position corresponding to the ON / OFF sensor 2_1 to 2_n that outputs.

The position calculation unit 3 can be realized by, for example, program processing by a program processing device such as a microcontroller or a CPU. In the case of the above example, it is realized by the IC chip 30 mounted on the printed circuit board 20.

More specifically, the position calculation unit 3 includes a reference value update unit 32, a relative position information acquisition unit 31, and a position determination unit 33.

The reference value update unit 32 is a functional unit that updates the reference value AP and outputs the reset signal RST when the detection signals P1 to Pn are output from the ON / OFF sensors 2_1 to 2_n.

Here, the reference value AP is a value indicating an absolute position within the rotatable range SR, and serves as a reference when calculating the absolute position of the valve shaft 200 in the rotation direction.

Specifically, the reference value updating unit 32 corresponds to the reference value AP and the ON / OFF sensor 2_1 to 2_n that outputs the detection signal each time the ON / OFF sensor 2_1 to 2_n outputs the detection signals P1 to Pn. Set to a value that indicates the position to be used. For example, in the case of the example of FIG. 2, when the valve shaft 200 first reaches the position Pa where the valve opening becomes 20% and the ON / OFF sensor 2_2 outputs the detection signal P2, the reference value update unit 32 sets the reference value AP to a value indicating the position Pa corresponding to the ON / OFF sensor 2_2. After that, when the valve shaft 200 further rotates and the valve shaft 200 reaches the position Pm where the valve opening degree becomes 50% and the ON / OFF sensor 2_3 outputs the detection signal P3, the reference value update unit 32 uses the reference value update unit 32 as a reference. The value AP is changed from the value indicating the position Pa to the value indicating the position Pm corresponding to the ON / OFF sensor 2_3.

The relative position information acquisition unit 31 is a functional unit that acquires the mechanical displacement Md of the valve shaft 200 in the rotation direction detected by the relative position sensor 1 and calculates the integrated value RP of the mechanical displacement Md. For example, the relative position information acquisition unit 31 counts the pulses output from the incremental rotary encoder as the relative position sensor 1 and calculates the integrated value RP of the number of pulses.

Further, when the reset signal RST is output from the reference value updating unit 32, the relative position information acquisition unit 31 resets the integrated value RP of the number of pulses counted up to that point. After the reset, the relative position information acquisition unit 31 resumes the pulse counting operation.

That is, the relative position information acquisition unit 31 resets the integrated value RP each time a detection signal is output from any of the ON / OFF sensors 2_1 to 2_n. Therefore, the integrated value RP calculated by the relative position information acquisition unit 31 is the cumulative number of pulses output from the rotary encoder from the time when the reference value AP is updated immediately before to the time when the reference value AP is updated next time. It becomes a value.

The position determination unit 33 is a mechanical displacement amount in the rotation direction of the valve shaft 200 based on the reference value AP generated by the reference value update unit 32 and the integrated value RP of the number of pulses calculated by the relative position information acquisition unit 31. And are added to calculate the absolute position of the valve shaft 200 in the rotatable range SR. The position determining unit 33 converts the calculated absolute position of the valve shaft 200 into a valve opening degree, and outputs the converted value as an actual opening degree PV.

The operation amount calculation unit 4 operates the valve shaft 200 based on the target value SP of the valve opening as the target position in the rotation direction of the valve shaft 200 and the actual opening PV calculated by the position calculation unit 3. It is a functional part that calculates. The operation amount calculation unit 4 can be realized by program processing by a program processing device such as a microcontroller or a CPU, as in the position calculation unit 3, for example. In the case of the above example, it is realized by the IC chip 30 mounted on the printed circuit board 20.

Specifically, the operation amount calculation unit 4 includes a target value acquisition unit 41, a deviation calculation unit 42, and an operation amount determination unit 43.

The target value acquisition unit 41 is a functional unit that acquires the target value SP of the valve opening degree given by, for example, a higher-level device (not shown) in the valve control system. The target value SP is set by communication from an external controller or an analog signal of, for example, 4-20 mA.

The deviation calculation unit 42 is a functional unit that calculates the deviation ΔP between the target value SP of the valve opening degree acquired by the target value acquisition unit 41 and the actual opening degree PV calculated by the position calculation unit 3.

The operation amount determination unit 43 calculates the operation amount MV required for the valve shaft 200 to reach the target position in the rotation direction based on the target value SP based on the deviation ΔP calculated by the deviation calculation unit 42.

The operation unit 5 is a functional unit that operates the valve shaft 200 within the rotatable range SR based on the operation amount MV calculated by the operation amount calculation unit 4. Specifically, the operation unit 5 includes an electric motor 52, an electric motor drive unit 51, and a speed reducer 53.

The electric motor 52 is a component that generates a rotational force for operating the valve shaft 200. Examples of the electric motor 52 include brushless motors, stepping motors, and synchronous motors.

The electric motor drive unit 51 is a functional unit that drives the electric motor 52. Specifically, the electric motor drive unit 51 rotates the output shaft of the electric motor 52 by applying a current (or voltage) corresponding to the operation amount MV calculated by the operation amount calculation unit 4 to the electric motor 52. ..

The speed reducer 53 is a power transmission mechanism that reduces the rotational force generated by the electric motor 52 and transmits it to the valve shaft 200. For example, the speed reducer 53 is composed of various gear mechanisms such as a planetary gear mechanism. By connecting the output shaft of the speed reducer 53 to the valve shaft 200, the valve shaft 200 can be rotated by the rotational force obtained by reducing the rotational force of the electric motor 52 by a predetermined reduction ratio.

<< Operating Principle of Rotation Control Device 100 According to Embodiment 1 >>
Next, the operating principle of the rotation control device 100 according to the first embodiment will be described.
First, the operation of returning to the origin by the rotation control device 100 will be described.

FIG. 4 is a diagram showing an operation flow in the origin return operation mode of the rotation control device 100 according to the first embodiment.
Here, a case where the valve shaft 200 has reached a position where the valve opening degree becomes 80% at the time of turning on the power of the rotation control device 100 will be described as an example.

When the power is turned on to the rotation control device 100, the rotation control device 100 starts the operation in the origin return operation mode in which the origin return process of the relative position sensor is performed. In the home position return operation mode, the rotation control device 100 drives the electric motor 52 in the direction of closing the control valve (S11). Specifically, the electric motor drive unit 51 drives the electric motor 52 based on the operation amount MV calculated by the operation amount determination unit 43 so that the valve opening degree becomes 0%.

Next, the rotation control device 100 determines whether or not the detection signal is output from the ON / OFF sensors 2_1 to 2_n (S12). If the detection signal is not output from the ON / OFF sensors 2-1 to 2_n in step S12, the rotation control device 100 continues to drive the electric motor 52 so that the valve opening degree becomes 0%.

On the other hand, when the detection signal is output from the ON / OFF sensors 2_1 to 2_n in step S12, the rotation control device 100 positions the valve shaft at the position corresponding to the ON / OFF sensors 2_1 to 2_n that output the detection signal. The reference value AP (initial point) when calculating the absolute position of 200 is used (S13).

For example, in the case of the example of FIG. 2, the valve shaft 200 rotates in the direction from the position where the valve opening is 80% to 0% in step S11, and then the valve shaft is moved to the position Pb where the valve opening is 70%. When 200 arrives, the detection signal P4 is output from the ON / OFF sensor 2_4. At this time, the reference value updating unit 32 in the position calculation unit 3 sets a value indicating the position Pb corresponding to the ON / OFF sensor 2_4 that has output the detection signal P4 as the reference value AP, and outputs the reset signal RST.

The relative position information acquisition unit 31 that has received the reset signal RST from the reference value update unit 32 resets the integrated value RP of the number of pulses counted up to that point (S14).

As a result, the home-returning process is completed, and the rotation control device 100 shifts from the home-returning operation mode to the normal operation mode.

Next, the operation of the rotation control device 100 in the normal operation mode after returning to the origin will be described.
FIG. 5 is a flow chart showing an operation flow in the normal operation mode of the rotation control device according to the first embodiment.

When the home position return operation mode ends, the rotation control device 100 shifts to the normal operation mode. In the normal operation mode, the rotation control device 100 waits until the host device instructs to change the target value SP of the valve opening degree (S20). When a change in the target value SP of the valve opening is instructed, the deviation calculation unit 42 of the rotation control device 100 determines the actual opening PV based on the absolute position of the valve shaft 200 calculated by the position calculation unit 3. Is larger than the target value SP instructed by the host device (S21).

In step S21, when the actual opening PV is larger than the target value SP, the rotation control device 100 drives the electric motor 52 in the direction of closing the control valve (S22a). Specifically, the operation amount determination unit 43 calculates the operation amount MV so that the valve opening becomes the target value SP based on the deviation ΔP calculated by the deviation calculation unit 42, and the electric motor drive unit 51 calculates the operation amount MV. , The electric motor 52 is driven based on the operation amount MV.

On the other hand, in step S21, when the actual opening PV is smaller than the target value SP, the rotation control device 100 drives the electric motor 52 in the direction of opening the control valve (S22b). Specifically, the operation amount determination unit 43 calculates the operation amount MV so that the valve opening becomes the target value SP based on the deviation ΔP calculated by the deviation calculation unit 42, and the electric motor drive unit 51 calculates the operation amount MV. , The electric motor 52 is driven based on the operation amount MV.

After step S22a or step S22b, the rotation control device 100 determines whether or not a detection signal is output from one of the ON / OFF sensors 2_1 to 2_n (S23).

In step S23, when the detection signal is not output from the ON / OFF sensors 2_1 to 2_n, the rotation control device 100 acquires the relative position information with the reference value AP set by the reference value update unit 32 immediately before. The actual opening PV (absolute position of the valve shaft 200) is determined based on the mechanical displacement of the valve shaft 200 based on the integrated value RP of the number of output pulses from the relative position sensor 1 calculated by the unit 31. Calculate (S26).

For example, if the detection signal has never been output from the ON / OFF sensors 2_1 to 2_n after the home return processing (steps S11 to S14) described above, the reference value set in step S13 of the home return operation mode By adding the amount of mechanical displacement of the valve shaft 200 based on the integrated value RP calculated by the relative position information acquisition unit 31 to the AP (the position where the valve opening is 70% in the above example), the actual displacement is achieved. Calculate the opening PV.

On the other hand, in step S23, when the detection signal is output from the ON / OFF sensors 2_1 to 2_n, the rotation control device 100 updates the reference value AP (S24). Specifically, the reference value updating unit 32 sets the position corresponding to the ON / OFF sensors 2_1 to 2_n that output the detection signal in the new reference value AP. For example, in the above-mentioned home position return operation mode, the detection signal P3 is output from the ON / OFF sensor 2_3 in step S23 immediately after the reference value AP is set to a value indicating the position Pb (valve opening: 70%). In this case, the reference value updating unit 32 changes the reference value AP from a value indicating the position Pb (valve opening: 70%) to a value indicating the position Pm (valve opening: 50%). At this time, the reference value updating unit 32 also outputs the reset signal RST.

The relative position information acquisition unit 31 that has received the reset signal RST from the reference value update unit 32 resets the integrated value RP of the number of output pulses of the relative position sensor 1 that has been counted up to that point (S25).

Next, the rotation control device 100 is based on the reference value AP set by the reference value update unit 32 in step S24 and the integrated value RP counted by the relative position information acquisition unit 31 after being reset in step S25. Then, the actual opening PV (absolute position of the valve shaft 200) is calculated (S26). For example, when the reference value AP is changed to a value indicating the position Pm (valve opening: 50%) in step S24, the reference value AP is counted by the relative position information acquisition unit 31 after step S25. The absolute position of the valve shaft 200 is calculated by adding the mechanical displacement amount of the valve shaft 200 based on the integrated value RP, and the actual opening PV is calculated from that position.

Next, the rotation control device 100 determines whether or not the actual opening PV calculated in step S26 matches the target value SP (S27).

If the actual opening PV does not match the target value SP in step S27, the process returns to step S21, and the rotation control device 100 again performs the above-mentioned processes (S21 to S26). On the other hand, in step S27, when the actual opening PV matches the target value SP, the rotation control device 100 ends a series of processes for setting the valve opening to the target value.

<< Effect of Rotation Control Device 100 According to Embodiment 1 >>
As described above, in the rotation control device 100 according to the present invention, the valve shaft 200 is fully closed in addition to the non-contact relative position sensor 1 as a position sensor for measuring the position of the valve shaft 200 in the rotation direction. It is equipped with ON / OFF sensors 2_2 to 2_4 that output a detection signal when the third position (Pa, Pm, Pb) excluding the position Pc and the fully open position Po is reached. The rotation control device 100 includes a reference value AP indicating a position corresponding to the ON / OFF sensor 2_2 to 2_4 that outputs the detection signal, and a mechanical detection by the relative position sensor 1 after the detection signal is output. The absolute position of the valve shaft 200 in the rotation direction is calculated based on the integrated value RP of the displacement Md.

According to this, not only the fully closed position Pc and the fully open position Po but also the third position can be regarded as a reference point in the position measurement of the valve shaft 200, that is, the “origin”, so that the fully closed position Pc or the fully open position is fully opened. Compared with the case where only the position Po is set as the origin, the time required for the origin return process can be shortened.

Specifically, when n ON / OFF sensors 2_1 to 2_n are arranged within the rotatable range SR, it is necessary to return the valve shaft 200 at the fully open position Po to the origin when the rotation control device 100 is turned on. The time T is represented by the following equation (1). Here, Tf is the time required for the valve shaft to move from the fully open position to the fully closed position (full stroke time).

For example, when five (n = 5) ON / OFF sensors 2_1 to 2_5 are arranged and the full stroke time Tf is 60 [seconds], the time required to return the valve shaft 200 at the fully open position Po to the origin. T is 60 / (5-1) = 15 [seconds].

As described above, according to the rotation control device 100 according to the present invention, the time required for returning the valve shaft 200 to the origin, which is required when the relative position sensor 1 such as the incremental rotary encoder is used, is shortened. Is possible.
That is, in a rotation control device that measures the position of the operation target axis in the rotation direction by a non-contact relative position sensor, the time required for returning to the origin of the operation target axis is shortened, and the position measurement error of the operation target axis is reduced. Can be made smaller.

Further, the rotation control device 100 according to the present invention performs the same process as the home return every time the valve shaft 200 passes through the third position excluding the fully closed position Pc and the fully open position Po. Specifically, when n = 5, the rotation control device 100 sets the reference value AP to the ON / OFF sensor that outputs the detection signal when the detection signal is output from the ON / OFF sensor 2_2 to 2___. The integrated value RP is reset while updating to the value indicating the position corresponding to 2_2 to 2_4.

According to this, even when the rotation control device 100 is operated for a long time, the cumulative back crash of the gears constituting the speed reducer 53 and the like described above, and the electric motor such as a stepping motor and a synchronous motor as the electric motor 52 Reduces the measurement error of the mechanical displacement of the valve shaft 200 by the relative position sensor 1 due to the step-out of the electric motor when the is used in the open loop and the fluctuation of the power supply frequency when the synchronous motor is used. can do. This makes it possible to control the valve opening degree of the control valve more accurately.

Further, according to the rotation control device 100, by providing a plurality of ON / OFF sensors 2_1 to 2_n, even if one of the ON / OFF sensors 2_1 to 2_n fails, the other ON / OFF sensors 2_1 to 2_n The valve opening control can be continued. As a result, the reliability of the rotation control device 100 can be improved.

Further, by increasing the number of ON / OFF sensors 2_1 to 2_n installed in the rotatable range SR, the time required for returning to the origin and the measurement error of the mechanical displacement amount of the valve shaft 200 by the relative position sensor 1 are further reduced. It becomes possible to do.

<Other configuration examples of cam members>
In the first embodiment described above, an example in which the cam members 24a and 24b are arranged on the main surfaces 20a and 20b of the printed circuit board 20, respectively, has been described. However, the arrangement of the cam members 24a and 24b is not limited to this. As described below, instead of the cam members 24a and 24b, for example, one plate-shaped member having a corrugated surface may be arranged on both main surfaces 20a and 20b of the printed circuit board 20. .. An example of the configuration of a discontinuous absolute position sensor using such a cam member will be described with reference to FIGS. 6A and 6B.

FIG. 6A is a diagram showing another configuration example of the discontinuous absolute position sensor, and FIG. 6B is a diagram schematically showing a part of a cross section at the circumference C1 in FIG. 6A, and the other configuration. It is a figure explaining the relationship between an electrode and a cam member in an example.

As shown in FIG. 6A, in the other configuration example, the electrodes 21a (21b) of the ON / OFF sensors 2_1 to 2_5 are centered on the axis of the valve shaft 200 on the main surface 20a (20b) of the printed circuit board 20. One cam member 34a (which is formed in an arc shape in a plan view) is common to the discontinuous absolute position sensors shown in FIGS. 3A to 3E in that they are arranged on the same circumference C1. 34b) are discontinuous as shown in FIGS. 3A to 3E in that they are arranged on the main surface 20a (20b) of the printed circuit board 20 and on the circumference C2 centered on the axis of the valve shaft 200, respectively. Different from the absolute position sensor.

In another configuration example, the cam members 34a and 34b are each formed of an insulating material. The surfaces of the cam members 34a and 34b are formed in a wavy shape along the circumference C2, respectively, and when arranged on both main surfaces 20a and 20b of the printed circuit board 20, in the radial direction centered on the valve shaft 200, The portion corresponding to the wavy bottom coincides with the electrodes 21a and 21b of the ON / OFF sensors 2_1 to 2_5.

Therefore, the contacts 201a and 201b of the short plate 201 move in the circumferential direction while being in contact with the cam members 34a and 34b, and when the valve shaft 200 is not at any of the predetermined positions, the cam members 34a and 34b are contacted. Since the other ends of 201a and 201b are moved in a direction away from both main surfaces 20a and 20b, in this case, the contacts 201a'and 201b'of the contacts 201a and 201b are the main surfaces 20a and 20b of the printed circuit board 20. Does not touch. On the other hand, when the valve shaft 200 is at any of the predetermined positions, the heights of the cam members 34a and 34b from both main surfaces 20a and 20b of the printed circuit board 20 are lowered, and the contacts 201a of the short plate 201 are lowered. , 201b come into contact with the electrodes 21a, 21b.

Further, as shown in FIG. 6B, by devising the surface shapes of the cam members 34a and 34b, the range W in which the contacts 201a and 201b of the short plate 201 can contact the electrodes 21a and 21b along the circumference C1 is set. It is desirable that the width is slightly wider than the width of the portions of the contacts 201a and 201b that come into contact with the electrodes 21a and 21b, and is as close as possible to the width of the contacts 201a and 201b. The reason is as follows.

Since the electrodes 21a and 21b have a width in the circumferential C1 direction, even if the valve shaft 200 reaches the same position, the rotation angle of the valve shaft and the output of the detection circuit are determined according to the direction when the valve shaft 200 reaches that position. So-called hysteresis occurs, in which the relationship between the two is different. On the other hand, as in the other configuration examples, the surface shapes of the cam members 34a and 34b are devised to limit the range in which the electrodes 21a and 21b and the contacts 201a and 201b can be electrically contacted to the interval W. Thereby, the hysteresis can be reduced.

<Modification example of discontinuous absolute position sensor>
As described above, the discontinuous absolute position sensor has hysteresis because the electrodes 21a and 21b of the ON / OFF sensor have a width in the circumferential C1 direction. Therefore, a modified example of the discontinuous absolute position sensor having a configuration for reducing this hysteresis will be described.

FIG. 7A is a diagram showing a modification of a discontinuous absolute position sensor, FIG. 7B is a diagram schematically showing a part of a cross section at a circumference C1 in FIG. 7A, and FIG. 7C is shown in FIG. 7A. It is a figure which shows the cross section in III-III shown, and is the figure explaining the relationship between an electrode and a cam member in this modification.
In the discontinuous absolute position sensor according to this modification, as shown in FIG. 7A, the electrodes 21a and 21b and the cam members 44a and 44b have the valve shaft 200 on the main surfaces 20a and 20b of the printed circuit board 20, respectively. It differs from the discontinuous absolute position sensor shown in FIGS. 3A to 3E in that it is arranged on the same circumference C1 centered on the axis of.

In another configuration example, the cam members 44a and 44b are each formed of an insulating material. Further, as shown in FIG. 7B, each of the cam members 44a and 44b extends between the adjacent electrodes 21a and 21b. Further, as shown in FIGS. 7A and 7B, of the cam members 44a and 44b, the opposite ends of the two adjacent cam members on the main surfaces 20a and 20b are one of the electrodes 21a and 21b, respectively. It covers the part. The opposing ends of two adjacent cam members on the main surfaces 20a, 20b are separated from each other on the electrodes 21a, 21b.

FIG. 7B illustrates that two adjacent first cam members 44a arranged on the first main surface 20a are arranged along the circumference C1 with an interval Wg. Similarly, the second cam members 44b adjacent to each other on the second main surface 20b are also arranged along the circumference C1 at intervals Wg. Therefore, the electrodes 21a and 21b are exposed over a distance Wg along the direction in which the contacts 201a and 201b of the short plate 201 move, that is, along the circumference C1, and the other parts are covered with the cam members 44a and 44b, respectively. It has been.

Therefore, when the valve shaft 200 is not in any of the predetermined positions, the contacts 201a and 201b of the short plate 201 come into contact with the cam members 44a and 44b, respectively, from both main surfaces 20a and 20b of the printed circuit board 20. When the valve shaft 200 is in any of the predetermined positions while moving in the direction of separation, the contacts 201a'and 201b' of the contacts 201a and 201b of the short plate 201 are respectively, as shown in FIGS. 7A and 7B. A detection signal is output in contact with the electrodes 21a and 21b.
At this time, as shown in FIG. 7B, the ends of the cam members 44a and 44b cover a part of the electrodes 21a and 21b, and the range in which the electrodes 21a and 21b and the contacts 201a and 201b can be electrically contacted is the interval Wg. Since it is limited to, the accuracy of the position detection of the valve shaft 20 can be improved and the hysteresis can be reduced.

Further, the cam members 44a and 44b in this modification have grooves formed along the circumference C1 in a state of being arranged on the main surfaces 20a and 20b of the printed circuit board 20. Therefore, as shown in FIG. 7A, when the valve shaft 200 is not in a predetermined position and the contacts 201a and 201b of the short plate 201 are located between the electrodes in a plan view, the contacts 201a and 201b The contacts 201a'and 201b'are in contact with the cam members 44a and 44b at positions other than the contacts 201a'and 201b', and as shown in FIG. 7C, the contacts 201a' and 201b'do not come into contact with the cam members 44a and 44b due to the groove. Therefore, it is possible to prevent wear of the contacts and contribute to the improvement of reliability and durability.
In this modification, an example in which the cam members 44a and 44b are provided with grooves as shown in FIG. 7C has been described, but instead of providing the grooves, as shown in FIG. 7D, the cam members 44a', Even if the cam members 44a'and 44b' are formed in a shape such that the thickness of 44b'or the height of the printed circuit board 20 from the main surfaces 20a and 20b decreases in the radial direction with respect to the valve shaft 200. Good.

<Effects of other configuration examples>
Since the electrodes 21a and 21b have a width in the circumferential C1 direction, even if the valve shaft 200 reaches the same position, the rotation angle of the valve shaft and the output of the detection circuit are determined according to the direction when the valve shaft 200 reaches that position. So-called hysteresis occurs, in which the relationship between the two is different. On the other hand, in the other configuration example, as shown in FIG. 7B, the ends of the cam members 44a and 44b cover a part of the electrodes 21a and 21b, and the electrodes 21a and 21b and the contacts 201a and 201b are formed. By limiting the range of electrical contact to the interval Wg, it is possible to approach the structure in which the contacts 201a and 201b and the electrodes 21a and 21b are in contact only when the valve shaft 200 is in a predetermined position. It is possible to improve the detection accuracy and reduce the hysteresis.

From the viewpoint of reducing hysteresis, accuracy can be improved by making this interval Wg as narrow as possible.
Further, by providing grooves in the cam members 44a and 44b and providing an inclined surface with respect to the main surfaces 20a and 20b of the printed circuit board 20, the contacts 201a'and 201b' of the contacts 201a and 201b are the electrodes 21a. It does not come into contact with the cam member or other members in any place other than. Therefore, the life and reliability of the ON / OFF sensor can be improved.

<Embodiment 2>
When the rotation control device according to the first embodiment is continuously operated without turning off the power, the process of returning to the origin is not performed for a long time, so that a speed reducer or the like is configured when the rotation direction of the valve shaft is switched. Due to the accumulation of back crashes that occur in the gears, there is a discrepancy between the integrated value of the output pulse number of the rotary encoder and the amount of mechanical displacement in the actual rotation direction of the valve shaft, resulting in an error in the valve opening measurement result. Occurs.
Further, even when a plurality of ON / OFF sensors are arranged, backlash may accumulate if the valve shaft repeatedly moves between adjacent ON / OFF sensors.

Therefore, the rotation control device according to the second embodiment is a rotation control device that measures the position of the operation target axis in the rotation direction by a non-contact relative position sensor, and reduces the measurement error due to the accumulation of backlash. With the goal.
<< Configuration of the rotation control device according to the second embodiment >>
FIG. 8 is a diagram showing the configuration of the rotation control device according to the second embodiment.
The rotation control device 100A according to the second embodiment counts the number of times the rotation direction of the valve shaft 200 is reversed, and when the count value exceeds the threshold value, the valve shaft is operated and detected by the relative position sensor. It differs from the rotation control device 100 according to the first embodiment in that it has a forced reset function based on the number of times the valve shaft 200 is reversed in the rotation direction, which resets the integrated value RP of the mechanical displacement Md. Since the other configurations including the configuration of the ON / OFF sensor are the same as those in the first embodiment described above, the common components are designated by the same reference numerals, and detailed description thereof will be omitted.

Specifically, the rotation control device 100A further includes a reversal number counting unit 6. The reversal count counting unit 6 counts the number of times the rotation direction of the valve shaft 200 as the operation target shaft is reversed and holds the count value. The inversion count counting unit 6 can be realized by, for example, a counter and a program built in the microcontroller.

For example, the reversal count counting unit 6 stores the direction in which the valve shaft 200 is rotated immediately before, and when the direction in which the valve shaft is rotated next is different from the direction in which the valve shaft 200 is rotated immediately before, the reversal number is counted. Increment Rc. On the other hand, when the direction in which the valve shaft is rotated next coincides with the direction in which the valve shaft 200 is rotated immediately before, the reversal count counting unit 6 does not increment the reversal count Rc.

Further, the inversion count counting unit 6 resets the inversion count Rc when a detection signal is output from the ON / OFF sensors 2_1 to 2_n. For example, the inversion count counting unit 6 resets the inversion number Rc in response to the reset signal RST output from the reference value updating unit 32.

The operation amount calculation unit 4A turns on the valve shaft 200 by operating the valve shaft 200 via the operation unit 5 when the reversal count Rc counted by the reversal count counting unit 6 exceeds a predetermined threshold value Rt. / OFF Rotate the sensor to the position corresponding to any one of 2_1 to 2_n.

Specifically, the manipulated variable determination unit 43A in the manipulated variable calculation unit 4A monitors the flip count Rc by the flip count counting unit 6. When the number of inversions Rc exceeds the threshold value Rt, the operation amount determination unit 43A rotates the valve shaft 200 to a position corresponding to any one of the ON / OFF sensors 2_1 to 2_n to reset the integrated value RP. Perform the process (forced reset process).

In the forced reset process, the valve shaft 200 is placed at a position corresponding to the ON / OFF sensor 2_1 to 2_n closest to the position of the valve shaft 200 (short plate 201) when the count value of the reversal count counting unit 6 exceeds the threshold value. From the viewpoint of time reduction, it is preferable to move the sensor. On the other hand, when the operation target shaft is a valve shaft, the valve may be moved in the closing direction or the opening direction depending on the intended use of the valve.

After the forced reset process, the operation amount determination unit 43A determines the operation amount MV based on the deviation ΔP calculated by the deviation calculation unit 42, similarly to the operation amount determination unit 43 according to the first embodiment.

<< Operating principle of the rotation control device 100A according to the second embodiment >>
Next, the operation of the rotation control device 100A according to the second embodiment in the normal operation mode will be described.
9A and 9B are flow charts showing an operation flow in the normal operation mode of the rotation control device 100A according to the second embodiment.

First, the rotation control device 100A shifts to the normal operation mode when the origin return operation mode ends, similarly to the rotation control device 100 according to the first embodiment. In the normal operation mode, the rotation control device 100A waits until the host device instructs to change the target value SP of the valve opening degree (S20).

When the change of the target value SP of the valve opening degree is instructed in step S20, in the second embodiment, the forced reset process (S3) based on the number of times the rotation direction of the valve shaft 200 is reversed is executed. The procedure of the forced reset process based on the number of inversions is shown in FIG. 9B.
First, in the rotation control device 100A, whether or not the valve shaft 200 is reversed, that is, whether the direction in which the valve shaft 200 is rotated is opposite to the direction in which the valve shaft 200 is rotated immediately before. It is determined whether or not (S30). If it is determined in step S30 that the valve shaft 200 does not reverse, the rotation control device 100A ends the forced reset process (S3) based on the number of reverse turns, returns to the main routine, and performs the processes of steps S21 to S27. Execute.
Since the series of processes from steps S21 to S27 are the same as those of the rotation control device 100 according to the first embodiment, detailed description thereof will be omitted.

On the other hand, when it is determined in step S30 that the valve shaft 200 is inverted, the inversion count counting unit 6 increments the inversion number Rc (S31).

Next, the manipulated variable determination unit 43A determines whether or not the inversion number Rc counted by the inversion number counting unit 6 is larger than the threshold value Rt (S32). In step S32, if the number of inversions Rc does not exceed the threshold value Rt, the rotation control device 100A ends the forced reset process (S3) based on the number of inversions, returns to the main routine, and rotates according to the first embodiment. The processes of steps S21 to S27 are executed in the same manner as in the control device 100.

On the other hand, in step S32, when the number of inversions Rc is larger than the threshold value Rt, the manipulated variable calculation unit 4A calculates (φh−φ) and (φ−φl), respectively, and (φ−φl) ≦ (φh). It is determined whether or not it is −φ) (S33). Here, φh indicates an opening corresponding to an ON / OFF sensor that is larger than the current valve opening φ and is closest to the current valve opening φ. For example, the current valve opening φ is 60%. For example, φh is 70% (Pb, 2_4). Further, φl indicates an opening degree corresponding to an ON / OFF sensor that is smaller than the current valve opening degree φ and is closest to the current valve opening degree φ. For example, if the current valve opening degree φ is 60%. , Φl is 50%% (Pm, 2_3).

As a result of the determination in step S33, when (φ−φl) ≦ (φh−φ), the manipulated variable calculation unit 4A moves the valve shaft 200 in the direction of closing the control valve (S34a). On the other hand, when (φ−φl)> (φh−φ), the manipulated variable calculation unit 4A moves the valve shaft 200 in the direction of opening the control valve (S34b).

After step S34a or step S34b, the rotation control device 100 determines whether or not a detection signal is output from the ON / OFF sensors 2_1 to 2_n (S35). If the detection signal is not output from the ON / OFF sensors 2_1 to 2_n in step S35, the rotation control device 100 returns to step S33 and performs the above-described processing (S33 to S35) again.

On the other hand, in step S35, when the detection signal is output from any one of the ON / OFF sensors 2_1 to 2_n, the rotation control device 100 stops the electric motor (S36) and updates the reference value AP. (S37). Specifically, the reference value updating unit 32 sets the position corresponding to the ON / OFF sensors 2_1 to 2_n that output the detection signal in the new reference value AP. At this time, the reference value updating unit 32 also outputs the reset signal RST.

The relative position information acquisition unit 31 receives the reset signal RST from the reference value update unit 32, and resets the integrated value RP of the number of output pulses from the relative position sensor 1 that has been counted up to that point (S38). ..

Further, the inversion count counting unit 6 receives the reset signal RST from the reference value updating unit 32 and resets the inversion count Rc counted up to that point (S39).

With the above, the forced reset process (S3) based on the number of inversions is completed, and the process returns to the main routine. After that, the rotation control device 100A performs the processes of steps S21 to S27 as in the rotation control device 100 according to the first embodiment. To execute.
When the integrated value RP is reset in step S25, the reversal count Rc by the reversal count counting unit 6 is also reset (step S39 in FIG. 9A).

<< Effect of rotation control device 100A according to the second embodiment >>
In a general control valve control system, the valve shaft 200 does not reach the position corresponding to the ON / OFF sensor 2_1 to 2_n for a long time, for example, the position where the valve shaft 200 corresponds to the ON / OFF sensor 2_2 (valve opening). The situation of going back and forth between the degree (20%) and the position corresponding to the ON / OFF sensor 2_3 (valve opening: 50%) may continue for a long time. In this case, backlash accumulates, and there is a possibility that an error may occur in the measurement result by the relative position sensor 1 (for example, an incremental rotary encoder).

On the other hand, according to the rotation control device 100A according to the second embodiment, when the number of inversions Rc exceeds a predetermined number (threshold value Rt), the integrated value RP is forcibly reset, so that even in the above-mentioned situation, the backlash It is possible to suppress the measurement error caused by the accumulation of rush.

As described above, according to the rotation control device 100A according to the second embodiment, it is possible to further reduce the error in the position measurement of the operation target axis.

<Embodiment 3>
The rotation control device 100B according to the third embodiment, like the rotation control device 100A according to the second embodiment, aims to reduce the measurement error due to the accumulation of backlash. The rotation control device 100A according to the second embodiment forcibly operates the valve shaft based on the number of times of reversal of the valve shaft 200 in the rotation direction, and the integrated value RP of the mechanical displacement Md detected by the relative position sensor. However, the rotation control device 100B according to the third embodiment forcibly operates the valve shaft based on the integrated value of the movement distance of the valve shaft of the valve shaft, and is relatively relative. The difference is that the integrated value RP of the mechanical displacement Md detected by the position sensor is configured to be reset.
<< Configuration of the rotation control device according to the third embodiment >>
FIG. 10 is a diagram showing the configuration of the rotation control device 100B according to the third embodiment.
The rotation control device 100B according to the third embodiment integrates the moving distance of the valve shaft of the valve shaft in a situation where the valve shaft 200 does not reach the position corresponding to the ON / OFF sensors 2_1 to 2_n for a long time, and the integrated value thereof. Has a forced reset function based on the so-called integrated value of the travel distance of the valve shaft 200, which resets the integrated value RP of the mechanical displacement Md detected by the relative position sensor by operating the valve shaft when the value exceeds the threshold value. In that respect, it differs from the rotation control device 100 according to the first embodiment and the rotation control device 100A according to the second embodiment. The configuration including the configuration of the ON / OFF sensor other than the forced reset process is the same as that of the first and second embodiments described above. Therefore, the common components are designated by the same reference numerals and the details thereof. Description will be omitted.

Specifically, the rotation control device 100B further includes an absolute value integrating unit 7. The absolute value integrating unit 7 integrates the moving distance of the valve shaft 200 as the operation target axis in the rotation direction, and holds the integrated value. More specifically, the absolute value integrating unit 7 integrates the absolute value | ΔP | of the mechanical displacement Md of the valve shaft 200 in the rotation direction. For example, the absolute value integrating unit 7 integrates the absolute value | ΔP | of the mechanical displacement Md detected by the relative position sensor 1 and stores the integrated value. Such an absolute value integrating unit 7 can be realized by, for example, a counter and a program built in the microcontroller.

Further, the absolute value integrating unit 7 resets the integrated value of the moving distance of the valve shaft B200 when the detection signal is output from the ON / OFF sensors 2_1 to 2_n. For example, the absolute value integrating unit 7 receives the reset signal RST output from the reference value updating unit 32, and resets the integrated value of the moving distance of the valve shaft 200 in the rotational direction.

The operation amount calculation unit 4B operates the valve shaft 200 via the operation unit 5 when the integrated value of the movement distance in the rotation direction of the valve shaft 200 integrated by the absolute value integration unit 7 exceeds a predetermined threshold value. As a result, the valve shaft 200 is rotated to a position corresponding to any one of the ON / OFF sensors 2_1 to 2_n.

Specifically, the manipulated variable determination unit 43B in the manipulated variable calculation unit 4B monitors the integrated value of the moving distance of the valve shaft 200 stored in the absolute value integrating unit 7. When the integrated value of the movement distance of the valve shaft 200 exceeds a predetermined threshold value, the operation amount determination unit 43B shifts the valve shaft 200 to a position corresponding to any one of the ON / OFF sensors 2_1 to 2_n. The process of resetting the integrated value RP by rotating the device (forced reset process) is performed.

After the forced reset process, the operation amount determination unit 43B determines the operation amount MV based on the deviation ΔP calculated by the deviation calculation unit 42, similarly to the operation amount determination unit 43 according to the first embodiment.

<< Operating principle of the rotation control device 100B according to the third embodiment >>
Next, the operation of the rotation control device 100B according to the third embodiment in the normal operation mode will be described.
11A and 11B are flow charts showing an operation flow in the normal operation mode of the rotation control device 100B according to the third embodiment.

First, the rotation control device 100B shifts to the normal operation mode when the origin return operation mode ends, similarly to the rotation control device 100 according to the first embodiment. In the normal operation mode, steps S22a and S22b for driving the electric motor from step S20 are the same as those in the first embodiment, and thus the description thereof will be omitted.

When the operation unit 5 drives the electric motor 52 to rotate the valve shaft 200 (step S22a or S22b), the rotation control device 100B executes a forced reset process (S4) based on the integrated value of the travel distance. FIG. 11B shows a procedure of the forced reset process based on the integrated value of the moving distance of the valve shaft 200.
As shown in FIG. 11B, first, the absolute value of the mechanical displacement Md due to the rotation of the valve shaft 200 by the operating unit 5, that is, the moving distance is integrated (S41).
Next, it is determined whether or not the integrated value of the travel distance integrated by the absolute value integrating unit 7 is larger than a predetermined threshold value (S42). In step S42, if the integrated value of the movement distance does not exceed the threshold value, the rotation control device 100B ends the forced reset process (S4) based on the integrated value of the orbital distance, returns to the main routine, and returns to the main routine, which is the embodiment. The processes of steps S23 to S27 are executed in the same manner as in the rotation control device 100 according to 1.

On the other hand, in step S42, when the integrated value of the movement distance is larger than the threshold value, the operation amount calculation unit 4B performs the forced reset process according to steps S33 to S38, similarly to the operation amount calculation unit 4A in the second embodiment. To execute. Procedure S33~S38 of the forced reset process, because it is identical to the procedure in the second embodiment, a description thereof will be omitted.

Further, when the detection signal is output from any of the ON / OFF sensors 2_1 to 2_n, the absolute value integrating unit 7 receives the reset signal RST from the reference value updating unit 32, and the valve shaft 200 up to that point receives the reset signal RST. The integrated value of the travel distance is reset (S49).

With the above, the forced reset process (S4) based on the movement distance is completed, and the process returns to the main routine. After that, the rotation control device 100B is the process of steps S23 to S27 as in the rotation control device 100 according to the first embodiment. To execute.
When the integrated value RP is reset in step S25, the integrated value of the moving distance stored in the absolute value integrating unit 7 is also reset (step S49 in FIG. 11A).

<< Effect of rotation control device 100B according to the third embodiment >>
If the valve shaft 200 does not reach the position corresponding to the ON / OFF sensor 2_1 to 2_n for a long time, backlash accumulates and the measurement result by the relative position sensor 1 (for example, an incremental rotary encoder). There is a risk of error.

On the other hand, according to the rotation control device 100B according to the third embodiment, the integrated value of the moving distance of the valve shaft 200 is calculated in a situation where the valve shaft 200 does not reach the position corresponding to the ON / OFF sensors 2_1 to 2_n for a long time. When the threshold value is exceeded, the integrated value RP is forcibly reset, so that it is possible to suppress the measurement error due to the accumulation of backlash.

Therefore, according to the rotation control device 100B according to the third embodiment, it is possible to further reduce the error in the position measurement of the operation target axis.

<Embodiment 4>
Similar to the rotation control device according to the second and third embodiments, the rotation control device according to the fourth embodiment also measures the position of the operation target axis in the rotation direction by a non-contact relative position sensor. The purpose is to reduce the measurement error due to the accumulation of backlash in the rotation control device.
<< Configuration of the rotation control device according to the fourth embodiment >>
FIG. 12 is a diagram showing the configuration of the rotation control device according to the fourth embodiment.
In the rotation control device 100C according to the second embodiment, when the valve shaft 200 does not reach the position corresponding to the ON / OFF sensors 2_1 to 2_n and the elapsed time without outputting the detection signal exceeds the threshold value. , The rotation control device according to the first to third embodiments is different in that the valve shaft is forcibly operated to reset the integrated value RP of the mechanical displacement Md detected by the relative position sensor. Hereinafter, the configuration including the configuration of the ON / OFF sensor other than the forced reset process is the same as that of the above-described first, second, and third embodiments. Therefore, the common components are designated by the same reference numerals. A detailed description will be omitted. The time elapsed without the valve shaft 200 reaching the position corresponding to the ON / OFF sensors 2-1 to 2_n and the detection signal being output may be referred to as "residence time".

Specifically, the rotation control device 100C has a timer 8. The timer 8 counts the time elapsed without the valve shaft 200 as the operation target shaft reaching the position corresponding to the ON / OFF sensor 2_1 to 2_n and the detection signal is not output, that is, the residence time, and counts the time. Hold the value. The timer 8 can be realized by, for example, a clock circuit, a counter, and a program built in the microcontroller.

For example, when the valve shaft 200 reaches the position corresponding to the ON / OFF sensors 2_1 to 2_n and the detection signal is detected, the timer 8 is reset once and counts the time elapsed from that position as the residence time.

When the residence time counted by the timer 8 exceeds a predetermined threshold value, the operation amount calculation unit 4C operates the valve shaft 200 via the operation unit 5 to turn on / off the valve shaft 200. Rotate to the position corresponding to any one of 2_n.

Specifically, the operation amount determination unit 43C in the operation amount calculation unit 4C monitors the residence time counted by the timer 8. When the residence time exceeds a predetermined threshold value, the operation amount determination unit 43C rotates the valve shaft 200 to a position corresponding to any one of the ON / OFF sensors 2_1 to 2_n, and the integrated value RP. Performs a process to reset (forced reset process).

After the forced reset process, the operation amount determination unit 43A determines the operation amount MV based on the deviation ΔP calculated by the deviation calculation unit 42, similarly to the operation amount determination unit 43 according to the first embodiment.

<< Operating Principle of Rotation Control Device 100C According to Embodiment 4 >>
Next, the operation of the rotation control device 100C according to the fourth embodiment in the normal operation mode will be described.
13A and 13B are flow charts showing an operation flow in the normal operation mode of the rotation control device 100C according to the fourth embodiment.

First , the rotation control device 100C shifts to the normal operation mode when the origin return operation mode ends, similarly to the rotation control device 100 according to the first embodiment. In the normal operation mode, the rotation control device 100C waits until the host device instructs to change the target value SP of the valve opening degree (S20).

When the change of the target value SP of the valve opening degree is instructed in step S20, the forced reset process (S5) based on the residence time is executed in the fourth embodiment. The procedure of the forced reset process based on this residence time is shown in FIG. 13B.
First, the manipulated variable determination unit 43C reads out the residence time stored in the timer 8 (S51) and determines whether or not the residence time is larger than the threshold value (S52). In step S52, if the residence time does not exceed the threshold value, the rotation control device 100C ends the forced reset process (S5) and returns to the main routine, similarly to the rotation control device 100 according to the first embodiment. , Steps S21 to S27 are executed.

On the other hand, in step S52, when the residence time is larger than the threshold value, the operation amount calculation unit 4C executes the forced reset process according to steps S33 to S38, similarly to the operation amount calculation unit 4A in the second embodiment. .. Procedure S33~S38 of the forced reset process, because it is identical to the procedure in the second embodiment, a description thereof will be omitted.

Further, when a detection signal is output from any of the ON / OFF sensors 2_1 to 2_n, the timer 8 receives the reset signal RST from the reference value update unit 32 and determines the residence time counted up to that point. Reset (S59).

With the above, the forced reset process (S3) based on the number of inversions is completed, and the process returns to the main routine. After that, the rotation control device 100C performs the processes of steps S21 to S27 in the same manner as the rotation control device 100 according to the first embodiment. To execute.
When the integrated value RP is reset in step S25, the residence time counted by the timer 8 up to that point is also reset (step S59 in FIG. 13A).

<< Effect of Rotation Control Device 100C According to Embodiment 4 >>
On the other hand, according to the rotation control device 100C according to the fourth embodiment, when the number of inversions Rc exceeds a predetermined number (threshold value Rt), the integrated value RP is forcibly reset. Therefore, even in the above-mentioned situation, the backlash is performed. It is possible to suppress the measurement error caused by the accumulation of rush.

As described above, according to the rotation control device 100C according to the fourth embodiment, it is possible to further reduce the error in the position measurement of the operation target axis.

<Embodiment 5>
The rotation control device 100D according to the fifth embodiment, like the rotation control device 100A according to the second embodiment, aims to reduce the measurement error due to the accumulation of backlash. The rotation control device 100A according to the second embodiment is configured to perform a forced reset process based on the number of times the valve shaft 200 is reversed in the rotation direction, whereas the rotation control device 100D according to the fifth embodiment is configured. The difference is that the forced reset process is performed based on the number of times the valve shaft 200 starts to move (hereinafter, may be referred to as “starting number”) regardless of the rotation direction of the valve shaft 200.

<< Configuration of the rotation control device according to the fifth embodiment >>
FIG. 14 is a diagram showing a configuration of the rotation control device 100D according to the fifth embodiment. The rotation control device 100D further includes a start count counting unit 9, and when the start count counted by the start count count unit 9 exceeds a predetermined threshold value Rt, the operation amount calculation unit 4D executes a forced reset process. To be equipped.
Since the other configurations including the configuration of the ON / OFF sensor are the same as those in the above-described first embodiment, the common components are designated by the same reference numerals, and detailed description thereof will be omitted. ..

The activation number counting unit 9 counts the number of times the valve shaft 200 as the operation target axis starts to move and holds the value Rs. Specifically, since the valve shaft rotates each time the target value ST is changed, the number of times the target value ST is changed may be counted as the number of activations. Such an activation count counting unit 9 can be realized by, for example, a counter and a program built in the microcontroller.
When the detection signal is output from any of the ON / OFF sensors 2-1 to 2-n, the activation count counting unit 9 receives the reset signal RST output from the reference value updating unit 32 of the position calculation unit 3. It will be reset.

In the normal operation mode, the operation amount calculation unit 4D is based on the target value SP of the valve opening as the target position in the rotation direction of the valve shaft 200 and the actual opening PV calculated by the position calculation unit 3. While calculating the operation amount of the valve shaft 200, when the forced reset process is executed, the valve shaft 200 is turned on by operating the valve shaft 200 via the operation unit 5, and the valve shaft 200 is turned on by any one of the ON / OFF sensors 2_1 to 2_n. Rotate to the position corresponding to.

More specifically, the operation amount determination unit 43D monitors the number of activations counted by the activation number counting unit 9. When the number of activations exceeds the threshold value, the operation amount determination unit 43D resets the integrated value RP by rotating the valve shaft 200 to a position corresponding to any one of the ON / OFF sensors 2_1 to 2_n. Perform processing (forced reset processing).

In the forced reset process, the valve shaft 200 is placed at a position corresponding to the ON / OFF sensor 2_1 to 2_n closest to the position of the valve shaft 200 (short plate 201) when the count value of the activation count unit 9 exceeds the threshold value. From the viewpoint of time reduction, it is preferable to move the sensor. On the other hand, when the operation target shaft is a valve shaft, the valve may be moved in the closing direction or the opening direction depending on the intended use of the valve.

After the forced reset process, the operation amount determination unit 43D determines the operation amount MV based on the deviation ΔP calculated by the deviation calculation unit 42, similarly to the operation amount determination unit 43 according to the first embodiment.

<< Operating Principle of Rotation Control Device 100D According to Embodiment 5 >>
Next, the operation of the rotation control device 100D according to the fifth embodiment in the normal operation mode will be described.
15A and 15B are flow charts showing an operation flow in the normal operation mode of the rotation control device 100D according to the fifth embodiment.

First, the rotation control device 100D shifts to the normal operation mode when the origin return operation mode ends, similarly to the rotation control device 100 according to the first embodiment. In the normal operation mode, the rotation control device 100D waits until the host device instructs to change the target value SP of the valve opening degree (S20).

When a change in the target value SP of the valve opening is instructed in step S20, a forced reset process (S6) based on the number of times the valve shaft 200 is started is executed.

The procedure of the forced reset process based on the number of activations is shown in FIG. 15B.
First, the activation number counting unit 9 of the rotation control device 100D increments the activation number (S61).

Next, the operation amount determination unit 43D determines whether or not the number of activations counted by the activation number counting unit 9 is larger than a preset threshold value (S62). In step S62, if the number of activations does not exceed the threshold value, the rotation control device 100D ends the forced reset process (S6) based on the number of inversions and returns to the main routine.

On the other hand, in step S62, when the number of activations is larger than the threshold value, the operation amount calculation unit 4B executes the forced reset process according to steps S33 to S38, similarly to the operation amount calculation unit 4A in the second embodiment. .. Procedure S33~S38 of the forced reset process, because it is identical to the procedure in the second embodiment, a description thereof will be omitted.

Further, when a detection signal is output from any of the ON / OFF sensors 2_1 to 2_n, the activation count counting unit 9 receives the reset signal RST from the reference value update unit 32 and resets the activation count up to that point. (S69).

With the above, the forced reset process (S6) based on the number of startups is completed, and the process returns to the main routine. After that, the rotation control device 100D executes the processes of steps S23 to S27 in the same manner as the rotation control device 100 according to the first embodiment.
Since the series of processes from steps S21 to S27 are the same as those of the rotation control device 100 according to the first embodiment, detailed description thereof will be omitted.
Further, when the integrated value RP is reset in step S25, the number of activations stored in the activation number counting unit 9 is also reset (step S69 in FIG. 15A).

<< Effect of Rotation Control Device 100D According to Embodiment 5 >>
According to the rotation control device 100D according to the fifth embodiment, when the number of activations exceeds a predetermined number (threshold value), the integrated value RP is forcibly reset, so that the measurement error due to the accumulation of backlash can be suppressed. It will be possible.

As described above, according to the rotation control device 100D according to the fifth embodiment, it is possible to further reduce the error in the position measurement of the operation target axis.

<Expansion of embodiment>
Although the inventions made by the present inventors have been specifically described above based on the embodiments, it goes without saying that the present invention is not limited thereto and can be variously modified without departing from the gist thereof. No.

For example, in the first embodiment described above, since the short plate 201 having a substantially “U” shape in the side view is used, the electrodes 21a and 21b and the cam member 24a are used on the two main surfaces 20a and 20b of the printed circuit board 20, respectively. , 24b has been described, but the electrode 21 and the cam member 24 may be arranged only on the printed circuit board 20, for example, the first main surface 20a.

Further, for example, in the above embodiment, the valve shaft 200 has a fully closed position Pc, a position Pa where the valve opening degree is 20%, a position Pm where the valve opening degree is 50%, and a valve opening degree 70%. Although the case where the five ON / OFF sensors 2-1 to 2_5 are installed at the five positions of the position Pb and the fully open position Po, respectively, the position and the number of the ON / OFF sensors to be installed are not limited to this. Hereinafter, another example of arrangement of the ON / OFF sensor will be shown.

FIG. 16A is a diagram showing another arrangement example of the ON / OFF sensor.
In this example, when n = 3, the valve shaft 200 has a fully closed position Pc in which the valve opening is 0%, an intermediate point between the fully closed position Pc and the fully open position Po, that is, an intermediate in which the valve opening is 50%. A case is shown in which three ON / OFF sensors 2_1, 2_2, and 2_3 are provided to detect that the position Pm and the fully opened position Po where the valve opening degree is 100% are reached. FIG. 16B is a diagram showing an arrangement example of the electrode 21 of the absolute position sensor and the cam member 24 corresponding to the arrangement example shown in FIG. 16A. As shown in FIG. 16B, a cam member 24 is provided between the electrodes 21 constituting the ON / OFF sensors 2_1, 2_2, and 2_3 in the circumferential direction.

According to this, when the valve shaft 200 reaches the fully closed position Pc, the fully open position Po, and the intermediate position Pm at the midpoint between the fully closed position Pc and the fully open position Po, the origin returns (update of the reference value AP). As compared with the case where only the fully closed position Pc or the fully open position Po is set as the origin of the valve shaft 200, the time required for returning to the origin and the measurement error of the mechanical displacement amount by the relative position sensor 1 are reduced. It becomes possible. In addition, it is possible to suppress the additional cost by installing the ON / OFF sensor.

In FIGS. 16A and 16B, the ON / OFF sensor is arranged not at both the fully closed position Pc where the valve opening is 0% and the fully open position Po where the valve opening is 100%, but at one of them. You may.

Further, FIG. 17A is a diagram showing still another example of arrangement of the ON / OFF sensor.
In this example, a case is shown in which one ON / OFF sensor 2 for detecting that the valve shaft 200 has reached the intermediate position Pm where the valve opening degree is 50% is provided. At this time, as shown in FIG. 17B, cam members 24 are arranged on both sides of the electrodes 21 constituting the ON / OFF sensor 2. These cam members are arranged along the trajectory of the contact point of the short plate 201 between the fully closed position Pc and the intermediate position Pm and between the intermediate position Pm and the fully open position Po.

According to this, since the origin return is performed at the position Pm which is the intermediate point between the fully closed position Pc and the fully open position Po, the origin return is performed as compared with the case where only the fully closed position Pc or the fully open position Po is set as the origin. It is possible to reduce the time required for the measurement and the measurement error of the mechanical displacement amount by the relative position sensor 1. Further, since only one ON / OFF sensor is required, it is possible to further reduce the additional cost due to the installation of the ON / OFF sensor.

Further, in the above embodiment, the case where the incremental type rotary encoder is used as the relative position sensor 1 is illustrated, but any mechanical displacement Md in the rotation direction of the operation target axis can be detected without contact. For example, it can be used as the relative position sensor 1. For example, when a brushless motor is used as the electric motor 52, the signal output from the Hall element (Hall IC) constituting the brushless motor can be used as the relative position sensor 1.

Further, when a stepping motor is used as the electric motor 52, the position calculation unit 3 counts the pulse signal for driving the stepping motor without separately providing the relative position sensor 1, so that the operation target axis can be operated. It is also possible to calculate the amount of mechanical displacement in the direction of rotation.

Further, when a synchronous motor is used as the electric motor 52, it is possible to calculate the amount of mechanical displacement of the operation target shaft in the rotational direction without separately providing the relative position sensor 1. For example, when the drive time for driving the synchronous motor is T [s], the rotation speed is N [rpm], and the reduction ratio of the reduction gear is 1 / G, the rotation angle Φ [°] is (T × N). It is represented by × 360) / (60 × G). Therefore, the position calculation unit 3 can calculate the amount of mechanical displacement of the operation target shaft in the rotation direction by performing the above calculation.

Further, in the above embodiment, the case where the rotation control device 100 is applied as an electric actuator for operating the valve shaft 200 of the control valve is illustrated, but the operation target shaft operated by the rotation control device 100 is a valve. It is not limited to the axis, and can be applied to any opening measurement system that uses a relative position sensor in the rotation control device. For example, the rotation control device 100 can be applied as an actuator for a damper that operates a damper shaft.

Further, in the above embodiment, the case where the valve shaft 200 is inserted through the through hole 20c formed in the printed circuit board 20 has been illustrated, but the present invention is not limited to this. For example, as shown in FIG. 18, a notch portion 20d having a semicircular shape in a plan view may be provided on one side of the printed circuit board 20, and the valve shaft 200 may be arranged in the notch portion 20d. In this case, the electrodes 21a may be arranged around the notch 20d on the main surface 20a of the printed circuit board 20.

100 ... Rotation control device (operator), 200 ... Valve shaft, 1 ... Relative position sensor, 2,2_1 to 2_n ... ON / OFF sensor, 3 ... Position calculation unit, 4,4A ... Operation amount calculation unit, 5 ... Operation unit, 6 ... Inversion count count unit, 7 ... Absolute value integration unit, 8 ... Timer, 9 ... Start count count unit, 20 ... Printed circuit board, 20a, 20b ... Main surface, 21a, 21b ... Electrode, 201 ... Short plate , 201a, 201b ... Contact, 23_i ... Detection circuit, 24a, 24b ... Cam member, 31 ... Relative position information acquisition unit, 32 ... Reference value update unit, 33 ... Position determination unit, 41 ... Target value acquisition unit, 42 ... Deviation calculation unit, 43 ... Operation amount determination unit, 51 ... Electric motor drive unit, 52 ... Electric motor, 53 ... Reducer, SP ... Target value, PV ... Actual opening, ΔP ... Deviation, MV ... Operation amount, RP … Integrated value, AP… Reference value, RST… Reset signal.

Claims (11)

A rotation control device that controls the rotation of the operation target axis.
A relative position sensor that non-contactly detects the mechanical displacement of the axis to be operated in the rotational direction,
When the operation target axis reaches at least one predetermined intermediate position excluding the first position and the second position in a rotatable range from the first position to the second position in the rotation direction of the operation target axis. An ON / OFF sensor that outputs a detection signal to
A reference indicating the integrated value of the mechanical displacement detected by the relative position sensor after the detection signal is output and the predetermined intermediate position corresponding to the ON / OFF sensor that outputs the detection signal. A position calculation unit that calculates the absolute position of the operation target axis in the rotation direction based on the value, and
The operation amount calculation unit that calculates the operation amount of the operation target axis based on the information of the target position in the rotation direction of the operation target axis and the absolute position of the operation target axis calculated by the position calculation unit. When,
Based on the operation amount calculated by the operation amount calculation unit, the operation unit that operates the operation target shaft within a rotatable range from the first position to the second position in the rotation direction of the operation target shaft. Prepare,
The ON / OFF sensor is
A substrate provided around the operation target axis and having a main surface orthogonal to the axis of the operation target axis.
With at least one electrode arranged on the main surface of the substrate,
One end is fixed to the operation target shaft, extends in the radial direction of the operation target shaft, and when the operation target shaft is in the predetermined intermediate position, a part of the other end side contacts one of the electrodes. With the contactor
A detection circuit that outputs the detection signal when the contactor comes into contact with one of the electrodes.
A cam member arranged on the main surface of the substrate and moving the other end of the contactor in a direction away from the main surface when the operation target axis is not in the predetermined intermediate position.
A rotation control device. In the rotation control device according to claim 1,
The electrodes are arranged at positions corresponding to the predetermined intermediate positions on the main surface.
The cam members are arranged along a circumference centered on the axis of the operation target axis, and the main surface is approached to a position corresponding to the predetermined intermediate position on the main surface along the circumference. The height from is low,
Rotation control device. In the rotation control device according to claim 2.
The electrode and the cam member are arranged along a first circumference and a second circumference having radii different from each other about the axis of the operation target axis on the main surface, respectively.
The opposite ends of the two cam members adjacent to each other on the main surface of the cam member are separated from each other on the main surface.
Rotation control device. In the rotation control device according to claim 2.
The electrode and the cam member are arranged on the same circumference centered on the axis of the operation target shaft on the main surface.
The cam members are each made of an insulating material.
The opposing ends of two adjacent cam members on the main surface of the cam member each cover a part of the electrode and are separated from each other on the electrode.
Rotation control device. In the rotation control device according to claim 4,
The contact is a plate-shaped member that can be elastically deformed.
The width of the portion that contacts the electrode when the operation target axis is at the predetermined intermediate position is narrower than the distance between the opposing ends of the two adjacent cam members on the main surface.
Rotation control device. In the rotation control device according to any one of claims 1 to 5.
The substrate has a first main surface and a second main surface opposite to the first main surface as the main surface.
The electrode comprises at least one first electrode arranged on the first main surface and at least one second electrode arranged on the second main surface.
One end of the contact is fixed to the operation target shaft, extends in the radial direction of the operation target shaft, and when the operation target shaft is in the predetermined intermediate position, a part of the other end side is the first. The first contactor in contact with one of the electrodes is electrically connected to the first contactor, and one end thereof is fixed to the operation target shaft and extends in the radial direction of the operation target shaft. When the operation target shaft is in the predetermined intermediate position, a part of the other end side is composed of a second contactor that comes into contact with one of the second electrodes.
The cam member is arranged on the first main surface of the substrate, and moves in a direction in which the other end of the first contact is separated from the main surface when the operation target axis is not in the predetermined intermediate position. A plurality of first cam members to be operated and the other end of the second contact are separated from the main surface when they are arranged on the second main surface of the substrate and the operation target axis is not in the predetermined intermediate position. Including a plurality of second cam members to be moved in the direction of
In the detection circuit, when a part of the other end side of the first contactor comes into contact with the first electrode and a part of the other end side of the second contactor comes into contact with the second electrode, the detection signal To output,
Rotation control device. In the rotation control device according to any one of claims 1 to 6.
Further, a reversing number counting unit for counting the number of times the rotation direction of the operation target axis is reversed is provided.
When the value counted by the inversion count counting unit exceeds a predetermined threshold value without outputting the detection signal, the operation amount calculation unit shifts the operation target axis to the first position and the second position. And the operation amount for moving to any one of the predetermined intermediate positions is calculated.
The operation unit operates the operation target axis based on the operation amount calculated by the operation amount calculation unit.
Rotation control device. In the rotation control device according to any one of claims 1 to 6.
Further provided with an absolute value integrating unit for integrating the absolute value of the mechanical displacement of the operation target shaft in the rotational direction.
The operation amount calculation unit shifts the operation target axis to the first position and the second position when the value integrated by the absolute value integration unit exceeds a predetermined threshold value without outputting the detection signal. And the operation amount for moving to any one of the predetermined intermediate positions is calculated.
The operation unit operates the operation target axis based on the operation amount calculated by the operation amount calculation unit.
Rotation control device. In the rotation control device according to any one of claims 1 to 6.
Further provided with a timer that integrates the elapsed time without outputting the detection signal.
When the time elapsed without outputting the detection signal exceeds a predetermined threshold value, the operation amount calculation unit sets the operation target axis at the first position, the second position, and the predetermined intermediate position. Calculate the operation amount to move to any one,
The operation unit operates the operation target axis based on the operation amount calculated by the operation amount calculation unit.
Rotation control device. In the rotation control device according to any one of claims 1 to 6.
Further provided with a start-up count unit for counting the number of times the operation target axis has started to move.
When the value counted by the activation number counting unit exceeds a predetermined threshold value without outputting the detection signal, the operation amount calculation unit shifts the operation target axis to the first position and the second position. And the operation amount for moving to any one of the predetermined intermediate positions is calculated.
The operation unit operates the operation target axis based on the operation amount calculated by the operation amount calculation unit.
Rotation control device. In the rotation control device according to any one of claims 1 to 10.
The position calculation unit
When the detection signal is output from the ON / OFF sensor, it includes a reference value update unit that resets the integrated value of the mechanical displacement detected by the relative position sensor.
Rotation control device.

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