JP7101459B2 - Electric actuator - Google Patents

Description

The present invention relates to an electric actuator.

An electric actuator equipped with a motor is used as a drive device for rotating the rotation operation shaft.

As an electric actuator of this type, for example, Patent Document 1 (Japanese Unexamined Patent Publication No. 2006-46318) describes an actuator that adjusts an opening degree by rotating a butterfly valve. Further, in Patent Document 2 (Japanese Unexamined Patent Publication No. 2009-270440), as a means for specifying the opening degree of the valve from the rotation angle of the motor, the rotor uses the phase change of the voltage output from the coil of the rotor in the motor. A configuration using a rotation angle sensor such as a resolver that detects the rotation angle of the above is described.

Japanese Unexamined Patent Publication No. 2006-46318 Japanese Unexamined Patent Publication No. 2009-270440

By the way, in the electric actuator provided with the rotation angle sensor as described above, it is one of the solutions to reduce the installation space of the rotation angle sensor in order to reduce the size.

Therefore, an object of the present invention is to provide an electric actuator capable of reducing the installation space of the rotation angle detecting device and reducing the size.

As a technical means for achieving the above-mentioned object, the present invention is electrically equipped with a motor unit for rotationally driving the rotation operation shaft via a speed reducer and a rotation angle detection device for detecting the rotation angle of the motor unit. The rotation angle detection device, which is an actuator, is configured to detect the magnetic flux of a magnet that is magnetized on different magnetic poles of the S pole and the N pole in the rotation direction of the motor unit and rotates integrally with the output shaft of the motor unit. Assuming that the movable range of the rotary operation shaft is θ °, the reduction ratio of the speed reducer is set to less than 360 ° / θ °.

By setting the reduction ratio of the speed reducer to less than 360 ° / θ ° with respect to the movable range (θ °) of the rotation operation shaft, the rotation range of the motor unit required for the rotation operation of the rotation operation shaft is 360. It will be possible to control in the range of less than °. In this case, the absolute value (rotation angle) of the rotation operation axis can be estimated by detecting the absolute angle position of the motor unit. Therefore, as a rotation angle detection device, the S pole is used in the rotation direction of the motor unit. The rotation angle of the motor unit can be detected and the rotation angle of the rotation operation shaft can be controlled by using a magnet that is magnetized to different magnetic poles of the N pole and detects the magnetic flux of the magnet that rotates integrally with the output shaft of the motor unit. It will be like. By using such a rotation angle detection device, it is possible to reduce the installation space as compared with a rotation angle sensor such as a resolver.

Further, as a rotation angle detection device that can reduce the installation space as described above, it is provided so as to rotate integrally with the output shaft of the motor unit, and detects magnets magnetized on different magnetic poles and the magnetic flux of the magnets. It is possible to use a magnetometer provided with a magnetic sensor capable of obtaining a sinusoidal output signal and a cosine wave output signal.

Further, the present invention can be applied to, for example, an electric actuator in which a connecting portion for connecting the rotation operation shafts so as to rotate integrally is arranged coaxially with the output shaft of the motor portion.

Further, when the electric actuator according to the present invention includes a magnet holding member for holding a magnet and a mounting member into which the magnet holding member is fitted, the mounting member is mounted on the inner peripheral surface of the output shaft of the motor unit. Magnets can be placed on the inner circumference of the output shaft. As a result, the space in the output shaft can be effectively used as the installation space for the magnet, and the size can be reduced.

Further, it is desirable that the mounting member has a dropout prevention portion provided so as to overlap the magnet holding member so that the magnet holding member does not fall off.

In addition, by forming a plurality of grooves at intervals in the circumferential direction of the outer peripheral edge of the mounting member and making the outer peripheral edge elastically deformable in the radial direction, the mounting member can be mounted in the output shaft of the motor section. It will be easy to do.

Further, the electric actuator according to the present invention can be applied to an electric actuator that rotates and operates the rotation operation shaft of the butterfly valve that adjusts the opening degree of the fluid passage.

According to the present invention, since the installation space of the rotation angle detecting device is reduced, the size of the electric actuator can be reduced.

It is an external view which shows the state which connected the electric actuator which concerns on one Embodiment of this invention to the rotation operation shaft of a butterfly valve. It is a vertical sectional view of the electric actuator which concerns on this embodiment. FIG. 2 is a cross-sectional view taken along the line YY of FIG. It is a waveform diagram of the output signal of a sine wave and the output signal of a cosine wave output by a magnetic sensor. It is a waveform diagram of the arctangent calculated from the output signal of a sine wave and the output signal of a cosine wave. It is sectional drawing of the area X in FIG. It is a perspective view of a mounting member. It is a vertical sectional view of the electric actuator which does not have a reducer. It is a vertical sectional view of the electric actuator suitable for making a series.

Hereinafter, a case where the electric actuator according to the present invention is applied to an actuator for a butterfly valve will be described as an example based on the attached drawings.

FIG. 1 is an external view of a state in which a butterfly valve is connected to an electric actuator according to the present embodiment.
As shown in FIG. 1, the butterfly valve 1 is composed of a disk-shaped valve body 2 as a rotation operation object and a rotation operation shaft 3 provided in a diameter portion of the valve body 2. The rotation operation shaft 3 is rotatably attached to the housing 5 in which the fluid passage 4 is formed, and the valve body 2 is arranged in the fluid passage 4. Further, one end of the rotation operation shaft 3 is connected to the electric actuator 6, and the rotation operation shaft 3 is rotated by the electric actuator 6, so that the valve body 2 rotates and the opening area of the fluid passage 4 is adjusted. Will be done.

FIG. 2 is a vertical sectional view of the electric actuator according to the present embodiment.
As shown in FIG. 2, the electric actuator 6 according to the present embodiment has a motor unit 7 as a drive source for driving the rotation operation shaft 3 to rotate, and the rotation of the motor unit 7 is decelerated and transmitted to the rotation operation shaft 3. The speed reducer 8 is the main component.

The motor unit 7 includes a stator 10 fixed to the casing 9, a rotor 11 arranged so as to face each other with a gap inside the stator 10 in the radial direction, and a cylindrical output shaft fixed to the inner peripheral surface of the rotor 11. It is composed of an electric motor provided with a twelve. Bearings 13 and 14 are fixed on the outer peripheral surfaces of the portion of the output shaft 12 to which the rotor 11 is fixed on both sides in the axial direction, respectively, and the output shaft 12 is rotated with respect to the casing 9 by these bearings 13 and 14, respectively. It is supported as much as possible. As the bearings 13 and 14, rolling bearings capable of supporting both radial load and thrust load, for example, deep groove ball bearings can be used.

The casing 9 is divided into one or a plurality of points in the axial direction for convenience of assembly. In the present embodiment, the casing 9 is divided into a bottom portion 91 having a bottomed cylindrical shape, a tubular portion 92 having both ends open, and a lid portion 93. The lid portion 93 is arranged on one side in the axial direction of the tubular portion 92, and the bottom portion 91 is arranged on the other side in the axial direction of the tubular portion 92. The bottom portion 91, the cylinder portion 92, and the lid portion 93 are integrated by using a fastening means such as a bolt. Of the bearings 13 and 14 that support the output shaft 12 of the motor unit 7, the bearing 13 on one side in the axial direction is fixed to the inner peripheral surface of the tubular portion 92, and the bearing 14 on the other side in the axial direction is the inner peripheral surface of the bottom 91. Is fixed to.

Subsequently, the configuration of the speed reducer 8 will be described with reference to FIG. 2 and FIG. 3, which is a cross-sectional view taken along the line YY of FIG.
The speed reducer 8 is a traction drive type planetary speed reducer including a sun roller 15, an outer ring 16, a plurality of planet rollers 17, and a carrier 18. In the present embodiment, the solar roller 15 is integrally provided at one end of the output shaft 12 of the motor unit 7 in the axial direction. The planet roller 17 is rotatably attached to the carrier 18 by a rolling bearing 20 (for example, a deep groove ball bearing) mounted on the outer periphery of the hollow shaft 19. The hollow shaft 19 sandwiches the inner ring of the rolling bearing 20 and the carrier 18 between the hollow shaft 19 and the flange portion provided at the other end portion by crimping one end portion in the axial direction (the right end portion in FIG. 2). It is fixed at.

The planet roller 17 is provided with traction (preload) in the inner diameter direction by the outer ring 16. Specifically, the outer ring 16 is reduced in diameter by press-fitting or shrinking the outer ring 16 into the casing 9 (cylinder portion 92) with a predetermined tightening allowance, and the contact portion between the outer ring 16 and the planet roller 17 and the planet. Traction is applied to the contact portion between the roller 17 and the solar roller 15.

The carrier 18 is connected so that the rotation operation shaft 3 rotates integrally, and functions as an output shaft that decelerates the rotation from the motor unit 7 to the rotation operation shaft 3 and outputs the rotation. The carrier 18 extends in the radial direction, extends from the central portion of the disc portion 181 to which the rolling bearing 20 and the planetary roller 17 are attached via the hollow shaft 19 to the output shaft 12 side of the motor portion 7, and outputs. The inner cylinder portion 182 arranged on the inner circumference of the shaft 12 and the outer side arranged on the axially outer side of the output shaft 12 extending from the central portion of the disk portion 181 to the side opposite to the output shaft 12 side of the motor portion 7. It has a cylinder portion 183. A rolling bearing 22 (for example, a deep groove ball bearing) is fixed to the outer peripheral surface of the inner tubular portion 182, and the carrier 18 is rotatably supported by the rolling bearing 22 with respect to the output shaft 12 of the motor portion 7. An annular seal member 21 is attached to the outer peripheral surface of the outer cylinder portion 183, and the seal member 21 seals between the outer cylinder portion 183 and the casing 9 (cover portion 93).

The inner cylinder portion 182 and the outer cylinder portion 183 are formed to have the same outer diameter and the same inner diameter, and are arranged coaxially with the output shaft 12 of the motor portion 7. A tubular heat insulating material 24 is inserted in the inner circumference thereof, and the rotation operation shaft 3 is connected to the inner cylinder portion 182 and the outer cylinder portion 183 via the heat insulating material 24. Therefore, on the inner circumference of the inner cylinder portion 182 and the outer cylinder portion 183, a connecting portion 23 connected so that the rotation operation shaft 3 rotates integrally is arranged coaxially with the output shaft 12 of the motor portion 7. ing. The heat insulating material 24 is connected to the inner peripheral surfaces of the inner tubular portion 182 and the outer tubular portion 183 by spline (or serration) fitting, and the rotation operation shaft 3 is also connected to the inner peripheral surface of the heat insulating material 24. They are connected by spline (or serration) fitting (see FIG. 3). The heat insulating material 24 is made of, for example, a heat-resistant synthetic resin in which GF (glass fiber) is mixed with PPS (polyphenylene sulfide), and the temperature of the valve that changes due to the passage of cold or hot air changes via the rotation operation shaft 3. It is provided to suppress the influence on the electric actuator 6.

In the electric actuator 6 provided with the speed reducer 8 configured as described above, when the output shaft 12 of the motor unit 7 rotates, the solar roller 15 integrated with the output shaft 12 rotates, so that the plurality of planetary rollers 17 rotate. While revolving along the outer ring 16. Then, the carrier 18 rotates due to the revolution motion of the planet roller 17, so that the rotation is decelerated and transmitted to the rotation operation shaft 3.

Further, as shown in FIG. 2, in the electric actuator 6 according to the present embodiment, a rotation angle detecting device 30 for detecting the rotation angle of the motor unit 7 is provided. The rotation angle detecting device 30 has a pair of magnets 31 and 32 magnetized on magnetic poles having different S poles and N poles in the rotation direction, and a magnetic sensor 33 for detecting the magnetic flux of each of the magnets 31 and 32. The magnets 31 and 32 are held by the magnet holding member 34, and the magnet holding member 34 is attached to the inner peripheral surface of the output shaft 12 of the motor unit 7 via the disk-shaped mounting member 35. On the other hand, the magnetic sensor 33 is fixed to the casing 9 (bottom 91) so as to face the magnets 31 and 32 at intervals.

When the motor unit 7 is driven and the output shaft 12 rotates, the magnets 31 and 32 rotate integrally with the output shaft 12, and the magnetic flux of each magnet 31 and 32 is detected by the magnetic sensor 33. The magnetic sensor 33 has two magnetic detection elements arranged with a predetermined phase difference (for example, 90 °) in the rotation direction, and a sine wave as shown in FIG. 4 from the magnetic flux detected by these two magnetic detection elements. The output signal of α and the output signal of the cosine wave β can be obtained. Then, the rotation angle is calculated by classifying the cases from the magnitude relation of these output signals. Specifically, the arctangent Arctan θ (= tan ^-1 (sin θ / cos θ)) is calculated from the output signal of the sine wave α and the output signal of the cosine wave β shown in FIG. As shown in FIG. 5, this inverse tangent Arctan θ has a characteristic that the waveform γ of the calculated angle with respect to the actual angle has a linearity. Therefore, by performing an angle calculation using this, the rotation angle of the output shaft 12 can be determined. Can be grasped. As a result, the output shaft 12 of the motor unit 7 can be rotated by a predetermined angle to adjust the opening degree of the butterfly valve to an appropriate degree.

Here, in the electric actuator according to the present invention, when the movable range (maximum rotation angle) of the rotation operation shaft 3 is θ °, the reduction ratio of the speed reducer 8 is set to be less than 360 ° / θ °. There is. For example, assuming that the movable range of the rotation operation shaft 3 is 90 °, the reduction ratio of the speed reducer 8 is set to less than 360 ° / 90 ° = 4.

As described above, in the electric actuator according to the present invention, by setting the reduction ratio of the speed reducer 8 to be less than 360 ° / θ °, the rotation of the motor unit 7 required for the rotation operation of the rotation operation shaft 3 is performed. The range can be controlled in the range of less than 360 °. In this case, since the absolute value (rotation angle) of the rotation operation shaft 3 can be estimated by detecting the absolute angle position of the motor unit 7, the rotation angle detection device can be used on different magnetic poles as described above. It is possible to use a rotation angle detecting device 30 including a pair of magnetized magnets 31 and 32 and a magnetic sensor 33 that can obtain an output signal of a sinusoidal wave and an output signal of a cosine wave by detecting these magnetic fluxes. become able to. By using such a rotation angle detection device 30, the installation space can be reduced as compared with a rotation angle sensor such as a resolver, and the size of the electric actuator can be reduced.

Further, as shown in FIG. 2, in the present embodiment, the magnets 31 and 32 are arranged on the inner circumference of the output shaft 12 of the motor unit 7, and the space inside the output shaft 12 is effective as the installation space for the magnets 31 and 32. By utilizing it, we are aiming for further miniaturization. That is, in the configuration of the present embodiment, it is not necessary to secure the installation space for the magnets 31 and 32 on the outer side of the output shaft 12 of the motor unit 7 in the axial direction, so that the miniaturization in the axial direction can be achieved.

As shown in FIG. 6, in the present embodiment, the magnets 31 and 32 are held by being fitted into the recess 34a provided in the center of the magnet holding member 34. Further, the magnet holding member 34 is fitted in the recess 35a provided in the center of the mounting member 35. By fitting the magnet holding member 34 into the recess 35a of the mounting member 35 in this way, the magnet holding member 34 is basically held so as not to fall off from the mounting member 35.

However, if there is anxiety about the holding force of the magnet holding member 34 by the mounting member 35, the mounting member 35 is further provided with a plurality of falling-off prevention portions 35b for preventing the magnet holding member 34 from falling off, as shown in FIG. You may. As a result, the magnet holding member 34 is regulated by the plurality of dropout prevention portions 35b so as not to fall off from the recess 35a of the mounting member 35. The fall-off prevention portion 35b is formed, for example, by crimping (bending) a notch piece formed by making a U-shaped notch in a sheet metal mounting member 35 so as to overlap the magnet holding member 34. be able to. Further, the fall prevention portion 35b is arranged so as not to overlap the magnets 31 and 32 so that the fall prevention portion 35b does not affect the magnetic flux of the magnets 31 and 32.

Further, as shown in FIG. 6, in the present embodiment, the inner peripheral surface of the output shaft 12 of the motor portion 7 is formed in a stepped shape, and the mounting member 35 is from the opening inner peripheral portion 12a on the magnetic sensor 33 side. Is also fitted and attached to the large diameter inner peripheral portion 12b formed on the inner side with a large inner diameter. In such a mounting structure, in order to insert the mounting member 35 into the large-diameter inner peripheral portion 12b from the magnetic sensor 33 side, it is necessary to elastically deform the mounting member 35 in the inner diameter direction at the opening inner peripheral portion 12a. Therefore, in the present embodiment, as shown in FIG. 7, a plurality of groove portions (notches) 35d are formed on the outer peripheral edge 35c of the mounting member 35 at intervals in the circumferential direction, and in particular, the outer peripheral edge 35c portion is in the inner diameter direction. It is formed so that it can be easily elastically deformed. This facilitates the work of mounting the mounting member 35 in the output shaft 12 of the motor unit 7.

In the present embodiment, a radial gap type electric motor including a stator 10 fixed to a casing 9 and a rotor 11 arranged so as to face each other with a gap inside the stator 10 in the radial direction is exemplified as a motor unit 7. However, a motor having any configuration can be adopted. For example, it may be an axial gap type electric motor including a stator fixed to a casing and a rotor arranged so as to face each other with a gap inside the stator in the axial direction.

Further, in the present embodiment, a traction drive type planetary reducer is adopted as a reducer having less backlash due to backlash and excellent in positioning accuracy in the rotation direction and low noise, but the gear is not limited to this. The planetary gear reducer used can also be used. Further, a speed reducer having a configuration other than the planetary speed reducer may be used.

Further, in the present embodiment, as a method of applying traction to the traction drive type planetary reducer, the outer ring 16 is compressed by press-fitting or shrinking the outer ring 16 onto the inner peripheral surface of the casing 9 with a predetermined tightening allowance. The method of making the diameter is given as an example, but the method is not limited to this, and any method can be adopted. For example, it is possible to impart traction by applying axial pressure to the outer ring 16 to elastically deform the outer ring 16 so as to bend toward the inner diameter side. In the method of reducing the diameter of the outer ring 16 by press fitting or shrink fitting, since the outer ring 16 does not have to be easily bent, the outer ring 16 having a block-shaped or solid cross section (see FIG. 2) is adopted. And the strength of the outer ring 16 can be improved.

FIG. 8 is a diagram showing an example of an electric actuator without a speed reducer.
In the electric actuator 6 shown in FIG. 8, since the speed reducer 8 as described above is not provided, the rotation operation shaft 3 is coaxially connected to the output shaft 12 of the motor unit 7 via the heat insulating material 24. Will be done. Further, in addition to the speed reducer 8, the rolling bearing 22 that supports the speed reducer 8, the lid portion 93 of the casing 9, and the seal member 21 arranged on the inner circumference of the lid portion 93 are not provided. Other than that, it has the same configuration as the electric actuator 6 shown in FIGS. 1 to 3.

Similar to the electric actuator according to the above-described embodiment, the electric actuator 6 also includes a pair of magnets 31 and 32 and a magnetic sensor 33 as a rotation angle detection device for detecting the rotation angle of the motor unit 7. By using the angle detection device 30, the installation space can be reduced and the size of the electric actuator can be reduced.

Further, the example shown in FIG. 9 is an electric actuator 6 provided with a speed reducer 8, but here, the outer cylinder portion 183 of the carrier 18 is formed larger in the radial direction than the inner cylinder portion 182. Then, the inner diameter φA1 and the outer diameter φB1 of the outer cylinder portion 183 are made the same size as the inner diameter φA2 and the outer diameter φB2 of the portion of the output shaft 12 of the motor portion 7 on the solar roller 15 side (right end portion in FIG. 9). (ΦA1 = φA2, φB1 = φB2). Further, in this configuration, the heat insulating material 24 is not inserted in the inner cylinder portion 182, and the rotation operation shaft 3 is connected via the heat insulating material 24 inserted in the outer cylinder portion 183. Other than that, the configuration is basically the same as that of the above-described embodiment shown in FIGS. 1 to 3.

With such a configuration, the member to be fitted to the outer peripheral surface or the inner peripheral surface of the outer cylinder portion 183 can also be fitted to the outer peripheral surface or the inner peripheral surface of the output shaft 12 of the motor portion 7. Therefore, a common member can be used depending on whether the speed reducer 8 is provided or not. For example, a type without the speed reducer 8 shown in FIG. 8 and a type with the speed reducer 8 shown in FIG. 9 have a heat insulating material 24 (FIG. 8) fitted in the output shaft 12 of the motor unit 7 and a carrier. A heat insulating material 24 having the same outer diameter can be used for the heat insulating material 24 (FIG. 9) to be fitted in the outer tubular portion 183 of 18. In particular, such a configuration is preferable because it is possible to make a series of electric actuators without changing many common parts when a wide variety of electric actuators are developed according to various uses.

It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention can be further implemented in various forms within a range not deviating from the gist of the present invention. In the above embodiment, the output shaft 12 of the motor unit 7 and the rotation operation shaft 3 are arranged coaxially, but the present invention is not limited to the case where it is applied to such an electric actuator. For example, even in an electric actuator in which the output shaft of the motor unit and the rotation operation shaft are arranged in parallel, the reduction ratio of the speed reducer can be set to less than 360 ° / θ ° (θ is the movable range of the rotation operation shaft). , The same rotation angle detection device as described above can be used, and the size of the electric actuator can be reduced. Further, the electric actuator according to the present invention is a rotation operation such as an EGR valve used in an exhaust gas recirculation system of an internal combustion engine, a throttle valve for adjusting an intake amount to a combustion engine to control engine output, a robot arm, or the like. It is applicable to devices and members whose shaft is rotated by rotation of the motor unit by less than 360 °.

3 Rotation operation shaft 6 Electric actuator 7 Motor unit 8 Reducer 12 Output shaft 23 Connecting unit 30 Rotation angle detection device 31 Magnet 32 Magnet 33 Magnetometer 34 Magnet holding member 35 Mounting member 35b Falling prevention unit 35c Outer peripheral edge 35d Groove

Claims (6)

The motor unit that drives the rotary operation shaft to rotate via the reducer,
An electric actuator provided with a rotation angle detecting device for detecting the rotation angle of the motor unit.
The rotation angle detection device is provided so as to rotate integrally with the output shaft of the motor unit, and detects a magnet magnetized on magnetic poles having different S poles and N poles in the rotation direction and the magnetic flux of the magnet. It has a magnetic sensor arranged so that a sinusoidal output signal and a cosine wave output signal can be obtained.
An electric actuator characterized in that the reduction ratio of the speed reducer is larger than 0 and less than 360 ° / θ °, where the movable range of the rotary operation shaft is θ °. The first aspect of the present invention, wherein the connecting portion for connecting the rotation operation shaft so as to rotate integrally is arranged coaxially with the output shaft of the motor portion. Electric actuator. A magnet holding member for holding the magnet and a mounting member into which the magnet holding member is fitted are provided.
The first or second aspect of the present invention, wherein the mounting member is mounted on the inner peripheral surface of the output shaft of the motor unit. Electric actuator. The third aspect of the present invention, wherein the mounting member has a fallout prevention portion provided so as to overlap the magnet holding member so that the magnet holding member does not fall off. Electric actuator. The third or fourth aspect of the present invention, wherein a plurality of grooves are formed at intervals in the circumferential direction of the outer peripheral edge of the mounting member, and the outer peripheral edge is elastically deformable in the radial direction. Electric actuator. The rotation operation shaft is the rotation operation shaft of a butterfly valve for adjusting the opening degree of a fluid passage, according to any one of claims 1 to 5. Electric actuator.

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