JP2018173024A - Electric actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that the number of components increases and the size and cost increase in a configuration where a rotation operation shaft and an output shaft of an actuator are connected in parallel.SOLUTION: An electric actuator includes a motor part 7 for rotatably driving a rotation operation shaft 3 of a valve for adjusting an opening degree of a fluid channel. A connection part 23 is disposed coaxially with an output shaft 12 of the motor part 7 inside the electric actuator, and connected to the rotation operation shaft 3 of the valve so as to rotate integrally with each other.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an electric actuator.

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

  As this type of electric actuator, for example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2006-46318) describes an actuator that rotates a butterfly valve to adjust the opening degree. In this configuration, the butterfly valve is disposed in parallel with the output shaft of the actuator, and the butterfly valve shaft (rotation operation shaft) and the output shaft of the actuator are connected via a gear.

JP 2006-46318 A

  However, in the configuration in which the butterfly valve and the output shaft of the actuator are connected in parallel via the gear, there are problems that the number of parts increases, and the size and cost increase.

  Therefore, an object of the present invention is to provide an electric actuator that reduces the number of parts and is advantageous for downsizing and cost reduction.

  As a technical means for achieving the above-described object, the present invention provides an electric actuator including a motor unit that rotationally drives a rotary operation shaft of a valve that adjusts the opening of a fluid passage, and is coaxial with an output shaft of the motor unit. In the electric actuator, a connecting portion connected so that the rotation operation shaft of the valve rotates integrally is arranged.

  Thus, in the electric actuator according to the present invention, the connecting portion connected so that the rotation operation shaft of the valve rotates integrally is coaxial with the output shaft of the motor portion and is inside the electric actuator. By being arranged, it is possible to achieve a reduction in size and cost in the radial direction as compared with a configuration in which an output shaft of an actuator and a rotation operation shaft such as a valve are arranged in parallel.

  Further, in a configuration including a speed reducer that decelerates rotation of the motor unit and transmits it to the rotation operation shaft, the speed reducer has an output shaft arranged coaxially with the output shaft of the motor unit. The connecting portion can be arranged coaxially with the output shaft of the motor portion on the inner periphery of the output shaft.

  By using a traction drive type planetary speed reducer as the speed reducer, it is possible to provide an electric actuator with less backlash due to backlash and excellent positioning accuracy in the rotational direction and low noise.

  Further, by providing a heat insulating material at the connecting portion, it is possible to reduce a temperature change of the electric actuator due to cold air or hot air on the rotating operation shaft side.

  According to the present invention, the number of components can be reduced, and the electric actuator can be reduced in size and cost.

It is an external view which shows the state which connected the electric actuator which concerns on one Embodiment of this invention to the rotating operation shaft of the butterfly valve. It is a longitudinal cross-sectional view of the electric actuator which concerns on this embodiment. FIG. 3 is a cross-sectional view taken along line YY in FIG. 2. It is a wave form diagram of the output signal of a sine wave and the output signal of a cosine wave which a magnetic sensor outputs. It is a waveform diagram of arc tangent calculated from the output signal of a sine wave and the output signal of a cosine wave. It is a longitudinal cross-sectional view of the electric actuator which has arrange | positioned the connection part to the axial direction outer side of the output shaft of a motor part. It is a longitudinal cross-sectional view of the electric actuator which has arrange | positioned the connection part on the outer side of the output shaft of a reduction gear. It is a longitudinal cross-sectional view of the electric actuator which is not provided with the reduction gear. It is a longitudinal cross-sectional view of the electric actuator suitable for series.

  Hereinafter, as an embodiment of an electric actuator according to the present invention, a case where the present invention is applied to an actuator for a butterfly valve will be described as an example with reference to the accompanying drawings.

FIG. 1 is an external view of a state in which a butterfly valve is connected to the electric actuator according to the present embodiment.
As shown in FIG. 1, the butterfly valve 1 includes a disc-like valve body 2 as a rotational operation target and a rotational operation shaft 3 provided at a diameter portion of the valve body 2. The rotary operation shaft 3 is rotatably attached to a housing 5 in which a fluid passage 4 is formed, and the valve body 2 is disposed in the fluid passage 4. Further, one end of the rotary operation shaft 3 is connected to the electric actuator 6, and the rotary operation shaft 3 is rotated by the electric actuator 6, whereby the valve body 2 rotates and the opening area of the fluid passage 4 is adjusted. Is done.

FIG. 2 is a longitudinal 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 includes a motor unit 7 as a drive source for rotationally driving the rotary operation shaft 3, and the rotation of the motor unit 7 is decelerated and transmitted to the rotary operation shaft 3. The reduction gear 8 is a main component.

  The motor unit 7 includes a stator 10 fixed to the casing 9, a rotor 11 disposed so as to face the radially inner side of the stator 10 with a gap, and a cylindrical output shaft fixed to the inner peripheral surface of the rotor 11. 12 and an electric motor. Bearings 13 and 14 are fixed to the outer peripheral surfaces of both sides in the axial direction of the portion where the rotor 11 of the output shaft 12 is fixed, and the output shaft 12 rotates with respect to the casing 9 by these bearings 13 and 14. Supported as possible. As the bearings 13 and 14, rolling bearings capable of supporting both radial loads and thrust loads, for example, deep groove ball bearings, can be used.

  The casing 9 is divided at one place or a plurality of places in the axial direction for the convenience of assembly. In the present embodiment, the casing 9 is divided into a bottomed cylindrical bottom portion 91, a cylindrical portion 92 that is open at both ends, and a lid portion 93. A lid portion 93 is disposed on one axial side of the cylindrical portion 92, and a bottom portion 91 is disposed on the other axial side of the cylindrical portion 92. The bottom part 91, the cylinder part 92, and the cover part 93 are integrated using fastening means, such as a volt | bolt. Of the bearings 13 and 14 that support the output shaft 12 of the motor unit 7, the bearing 13 on one axial side is fixed to the inner peripheral surface of the cylindrical portion 92, and the bearing 14 on the other axial side is the inner peripheral surface of the bottom 91. Fixed to.

Next, the configuration of the speed reducer 8 will be described based on FIG. 2 and FIG. 3 which is a cross-sectional view taken along line YY in 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 planetary rollers 17, and a carrier 18. In the present embodiment, the sun roller 15 is integrally provided at one axial end of the output shaft 12 of the motor unit 7. The planetary 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 is clamped at one end in the axial direction (the right end in FIG. 2) to sandwich the inner ring of the rolling bearing 20 and the carrier 18 between the flange provided at the other end. It is fixed with.

  The planetary roller 17 is given 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 shrink-fitting 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 planetary roller 17, and the planet Traction is imparted to the contact portion between the roller 17 and the sun roller 15.

  The carrier 18 is connected so that the rotation operation shaft 3 rotates integrally, and functions as an output shaft that decelerates and outputs the rotation from the motor unit 7 to the rotation operation shaft 3. The carrier 18 extends in the radial direction, extends from the center portion of the disk portion 181 to the output shaft 12 side of the motor portion 7 to the output shaft 12 side through which the rolling bearing 20 and the planetary roller 17 are attached via the hollow shaft 19. An inner cylindrical portion 182 disposed on the inner periphery of the shaft 12 and an outer portion that extends from the center of the disk portion 181 to the side opposite to the output shaft 12 side of the motor portion 7 and is disposed outside the output shaft 12 in the axial direction. And a cylindrical portion 183. A rolling bearing 22 (for example, a deep groove ball bearing) is fixed to the outer peripheral surface of the inner cylindrical portion 182, and the carrier 18 is rotatably supported by the rolling bearing 22 with respect to the output shaft 12 of the motor unit 7. An annular seal member 21 is mounted on the outer peripheral surface of the outer cylinder portion 183, and the space between the outer cylinder portion 183 and the casing 9 (lid portion 93) is sealed by the seal member 21.

  The inner cylinder part 182 and the outer cylinder part 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 part 7. A cylindrical heat insulating material 24 is inserted into the inner periphery thereof, and the rotary operation shaft 3 is connected to the inner cylindrical portion 182 and the outer cylindrical portion 183 through the heat insulating material 24. Therefore, a connecting portion 23 connected so that the rotation operation shaft 3 rotates integrally is disposed coaxially with the output shaft 12 of the motor portion 7 on the inner periphery of the inner cylindrical portion 182 and the outer cylindrical portion 183. ing. The heat insulating material 24 is connected to the inner peripheral surfaces of the inner cylindrical portion 182 and the outer cylindrical portion 183 by spline (or serration) fitting, and the rotary operation shaft 3 is also connected to the inner peripheral surface of the heat insulating material 24. Are connected by spline (or serration) fitting (see FIG. 3). The heat insulating material 24 is composed 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 when cold air or hot air passes through the rotary operation shaft 3. In order to suppress the influence on the electric actuator 6.

  In the electric actuator 6 including the speed reducer 8 configured as described above, when the output shaft 12 of the motor unit 7 rotates, the sun 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 by the revolving motion of the planetary roller 17, whereby the rotation is decelerated and transmitted to the rotation operation shaft 3.

  As shown in FIG. 2, the electric actuator 6 according to the present embodiment is provided with a rotation angle detection device 30 that detects the rotation angle of the motor unit 7. The rotation angle detection device 30 includes a pair of magnets 31 and 32 that are magnetized on different magnetic poles of S and N poles in the rotation direction, and a magnetic sensor 33 that detects the magnetic flux of each magnet 31 and 32. The magnets 31 and 32 are held by a 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 via a disk-like attachment member 35. On the other hand, the magnetic sensor 33 is fixed to the casing 9 (bottom portion 91) so as to face the magnets 31 and 32 with a space therebetween.

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 sensor 33 detects the magnetic flux of the magnets 31 and 32. 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. An output signal of α and an output signal of cosine wave β are obtained. Then, the rotation angle is calculated by classifying the output signals according to the magnitude relationship. Specifically, the arc tangent 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, the arc tangent Arctan θ has a characteristic that the waveform γ of the calculated angle with respect to the actual angle has linearity. Therefore, by performing an angle calculation using this, the rotation angle of the output shaft 12 can be calculated. I can grasp it. Thereby, the output shaft 12 of the motor unit 7 can be rotated by a predetermined angle, and the opening degree of the butterfly valve can be adjusted to an appropriate degree.

  In the electric actuator 6 according to the present embodiment configured as described above, the connecting portion 23 is arranged coaxially with the output shaft 12 of the motor portion 7, so that the rotary operation shaft 3 is output from the motor portion 7. The shaft 12 can be connected coaxially. As a result, it is possible to reduce the size and cost in the radial direction as compared with the conventional configuration in which the output shaft of the actuator and the rotation operation shaft such as a valve are arranged in parallel.

  Further, in the electric actuator 6 according to the present embodiment, the connecting portion 23 is disposed inside the electric actuator 6. That is, at least a part of the carrier 18 (inner cylinder part 182) is coaxially arranged on the inner circumference of the output shaft 12 of the motor part 7, and the connecting part 23 is arranged on the inner circumference of this part (inner cylinder part 182). The connecting portion 23 is arranged inside the electric actuator 6 (in this case, the inner circumference of the output shaft 12 of the motor portion 7). As described above, the connecting portion 23 is arranged inside the electric actuator 6, and the space in the electric actuator 6 is effectively used as the arrangement space of the connecting portion 23, whereby the electric actuator can be downsized.

  Further, in this embodiment, the rolling bearing 22 that supports the carrier 18 is disposed on the inner periphery of the output shaft 12 of the motor unit 7, thereby effectively utilizing the space in the output shaft 12. Thereby, since it is not necessary to ensure the space which arrange | positions the rolling bearing 20 in the area | region of the axial direction outer side of the output shaft 12 of the motor part 7, size reduction of the axial direction of an electric actuator can also be achieved.

  In the present embodiment, the connecting portion 23 has a spline fitting structure. However, when the rotating operation shaft 3 is inserted into the heat insulating material 24, a spline-shaped protrusion formed in advance on the outer peripheral surface of the rotating operation shaft 3. By press-fitting while cutting the inner peripheral surface of the heat insulating material 24 by the portion, high adhesion can be obtained between the heat insulating material 24 and the rotary operation shaft 3. The inner peripheral surface of the heat insulating material 24 may be a uniform cylindrical surface without unevenness, or a spline-shaped concave portion having a tightening margin with respect to the spline-shaped convex portion formed on the rotary operation shaft 3. It may be formed in advance. As described above, since the spline fitting structure with high adhesiveness can reduce the backlash in the rotational direction between the heat insulating material 24 and the rotary operation shaft 3, positioning of the butterfly valve in the rotational direction can be reduced. Accuracy can be improved. Similarly, when the heat insulating material 24 is fitted to the carrier 18 (the inner cylindrical portion 182 and the outer cylindrical portion 183), the heat insulating material 24 is placed in the carrier 18 in which spline-shaped convex portions are formed in advance on the inner peripheral surface. By press-fitting, it is possible to cut the outer peripheral surface of the heat insulating material 24 with the convex portion and obtain a spline fitting structure with high adhesion.

  In the present embodiment, a radial gap type electric motor including the stator 10 fixed to the casing 9 and the rotor 11 disposed so as to face the inner side in the radial direction of the stator 10 with a gap is illustrated as the motor unit 7. However, a motor having an arbitrary configuration can be employed. For example, an axial gap type electric motor including a stator fixed to a casing and a rotor arranged so as to face the inner side in the axial direction of the stator with a gap may be used.

  In this embodiment, a traction drive type planetary speed reducer is adopted as a speed reducer that has little backlash due to backlash and is excellent in rotational positioning accuracy and low noise.However, the gear is not limited to this. It is also possible to use the planetary gear reducer used. Moreover, you may use the speed reducer which has structures other than a planetary speed reducer.

  In the present embodiment, as a technique for imparting traction to the traction drive type planetary speed reducer, the outer ring 16 is compressed by press-fitting or shrink-fitting the outer ring 16 to the inner peripheral surface of the casing 9 with a predetermined tightening allowance. Although the method of making a diameter was given as an example, the present invention is not limited to this, and any method can be adopted. For example, traction can be imparted by applying an axial pressure to the outer ring 16 and elastically deforming the outer ring 16 so as to bend toward the inner diameter side. Note that the method of reducing the diameter of the outer ring 16 by press-fitting or shrink-fitting does not require the outer ring 16 to be easily bent, so the outer ring 16 having a block shape or a solid cross section (see FIG. 2) is employed. And the strength of the outer ring 16 can be improved.

  In this embodiment, in order to reduce the size of the electric actuator, a part of the carrier 18 (inner cylinder part 182) is configured to enter the output shaft 12 of the motor part 7, but FIG. It is good also as a structure which does not enter the carrier 18 in the output shaft 12 of the motor part 7 (it does not have the inner cylinder part 182) like the structure shown. In this case, the rotation operation shaft 3 is inserted and connected only to the outer cylindrical portion 183 of the carrier 18. In addition, the rolling bearing 22 that supports the carrier 18 is fixed to the outer peripheral surface of the outer cylindrical portion 183, and is disposed on the outer side in the axial direction of the output shaft 12 of the motor portion 7. For this reason, the axial direction dimension of the electric actuator 6 becomes large compared with embodiment shown in FIGS. However, even in this configuration, the connecting portion 23 is coaxial with the output shaft 12 of the motor portion 7 and is inside the electric actuator 6 (in this case, inside the outer cylindrical portion 183 of the carrier 18). Compared to the configuration in which the output shaft of the actuator and the rotary operation shaft such as a valve are arranged in parallel, the radial direction can be reduced and the cost can be reduced. In the configuration shown in FIG. 6, the configuration other than the portion described above is omitted by giving the same reference numerals to members having the same functions as those in FIGS.

  In the present embodiment described above, the connecting portion 23 is arranged coaxially with the output shaft 12 of the motor portion 7, and is connected to the inner periphery of the output shaft (inner cylinder portion 182 or outer cylinder portion 183) of the speed reducer 8. Although the portion 23 is arranged, the connecting portion 23 may be arranged on the outer periphery of the output shaft of the speed reducer 8.

  For example, as shown in FIG. 7, a flange portion 184 may be provided on the outer periphery of the outer cylindrical portion 183 of the carrier 18, and the flange portion 184 may be used as a connecting portion 23 to which the rotary operation shaft 3 is connected. In the configuration shown in FIG. 7, the flange portion 3 a provided on the rotation operation shaft 3 is fastened to the flange portion 184 of the carrier 18 via a heat insulating material 24 using fastening means (not shown) such as a bolt. . Even in such a configuration, the connecting portion 23 is arranged coaxially with the output shaft 12 of the motor unit 7, so that the rotation operation shaft 3 is coaxial with the output shaft 12 of the motor unit 7 with respect to the electric actuator. It becomes possible to connect directly, and size reduction and cost reduction in the radial direction can be achieved. The embodiment shown in FIG. 7 is the same as the electric actuator 6 shown in FIGS. 1 to 3 except for the configuration described above.

  Moreover, this invention is applicable not only to the electric actuator provided with a reduction gear but to the thing which is not provided with the reduction gear.

FIG. 8 is a view showing an embodiment in which the present invention is applied to an electric actuator not provided with a reduction gear.
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 connected to the inner peripheral surface of the output shaft 12 of the motor unit 7 via the heat insulating material 24. It is connected on the same axis. That is, also in this case, the connecting portion 23 is coaxial with the output shaft 12 of the motor unit 7 and is disposed inside the electric actuator 6 (in this case, within the output shaft 12 of the motor unit 7). Thus, it is possible to reduce the size and cost in the radial direction. In the electric actuator 6 shown in FIG. 8, 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 disposed on the inner periphery of the lid portion 93. Is not provided. Other than that, it is the structure similar to the electric actuator 6 shown to the said FIGS. 1-3.

  The example shown in FIG. 9 is the electric actuator 6 including the 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. The inner diameter φA1 and the outer diameter φB1 of the outer cylinder portion 183 are set to 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 sun roller 15 side (the right end portion in FIG. 9). (ΦA1 = φA2, φB1 = φB2). In this configuration, the heat insulating material 24 is not inserted into the inner cylindrical portion 182, and the rotary operation shaft 3 is connected via the heat insulating material 24 inserted into the outer cylindrical portion 183. Other than that, the configuration is basically the same as that of the above-described embodiment shown in FIGS.

  By adopting such a configuration, the member fitted to the outer peripheral surface or inner peripheral surface of the outer cylindrical portion 183 can be fitted also to the outer peripheral surface or inner peripheral surface of the output shaft 12 of the motor unit 7. Thus, a common member can be used when the reduction gear 8 is provided and when the reduction gear 8 is not provided. For example, a heat insulator 24 (FIG. 8) that fits in the output shaft 12 of the motor unit 7 in a type that does not include the speed reducer 8 illustrated in FIG. 8 and a type that includes the speed reducer 8 illustrated in FIG. The heat insulating material 24 having the same outer diameter can be used as the heat insulating material 24 (FIG. 9) to be fitted into the 18 outer cylindrical portion 183. In particular, such a configuration is preferable because the electric actuator can be made into a series without changing many common parts when various types of electric actuators are developed according to various applications.

  It should be noted that the present invention is not limited to the above-described embodiment, and can of course be implemented in various forms without departing from the gist of the present invention. An electric actuator according to the present invention includes an EGR valve used in an exhaust gas recirculation system of an internal combustion engine, a throttle valve that adjusts an intake air amount to a combustion engine to control engine output, and a ball valve other than a butterfly valve It is applicable to the above.

3 Rotating operation shaft 6 Electric actuator 7 Motor unit 8 Reducer 12 Output shaft (output shaft of motor unit)
18 Carrier (Speed reducer output shaft)
23 connecting part 24 heat insulating material

Claims (4)

In an electric actuator including a motor unit that rotationally drives a rotary operation shaft of a valve that adjusts the opening of a fluid passage,
An electric actuator, characterized in that a connecting portion that is coaxial with an output shaft of the motor portion and is connected inside the electric actuator so as to integrally rotate a rotation operation shaft of the valve. A speed reducer that decelerates the rotation of the motor unit and transmits it to the rotation operation shaft;
The speed reducer has an output shaft disposed coaxially with the output shaft of the motor unit,
The electric actuator according to claim 1, wherein the connecting portion is disposed coaxially with the output shaft of the motor unit on the inner periphery of the output shaft of the speed reducer.   The electric actuator according to claim 2, wherein the reduction gear is a traction drive type planetary reduction gear.   The electric actuator of any one of Claim 1 to 3 which provided the heat insulating material in the said connection part.

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