WO2023276999A1 - 直動アクチュエータ - Google Patents
直動アクチュエータ Download PDFInfo
- Publication number
- WO2023276999A1 WO2023276999A1 PCT/JP2022/025704 JP2022025704W WO2023276999A1 WO 2023276999 A1 WO2023276999 A1 WO 2023276999A1 JP 2022025704 W JP2022025704 W JP 2022025704W WO 2023276999 A1 WO2023276999 A1 WO 2023276999A1
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- WIPO (PCT)
- Prior art keywords
- shaft
- linear motion
- hole
- screw shaft
- rotor
- Prior art date
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- 230000007246 mechanism Effects 0.000 claims abstract description 104
- 238000006243 chemical reaction Methods 0.000 claims abstract description 42
- 239000000463 material Substances 0.000 claims description 18
- 230000004048 modification Effects 0.000 description 32
- 238000012986 modification Methods 0.000 description 32
- 239000002184 metal Substances 0.000 description 27
- 239000011347 resin Substances 0.000 description 27
- 229920005989 resin Polymers 0.000 description 27
- 230000009467 reduction Effects 0.000 description 26
- 241001232202 Chrysothamnus stylosus Species 0.000 description 7
- 239000012530 fluid Substances 0.000 description 5
- 235000019589 hardness Nutrition 0.000 description 5
- 230000006872 improvement Effects 0.000 description 3
- 230000007423 decrease Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000003780 insertion Methods 0.000 description 2
- 230000037431 insertion Effects 0.000 description 2
- 239000007769 metal material Substances 0.000 description 2
- 238000000465 moulding Methods 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
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Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K7/00—Arrangements for handling mechanical energy structurally associated with dynamo-electric machines, e.g. structural association with mechanical driving motors or auxiliary dynamo-electric machines
- H02K7/06—Means for converting reciprocating motion into rotary motion or vice versa
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
- F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
- F16H25/20—Screw mechanisms
- F16H25/24—Elements essential to such mechanisms, e.g. screws, nuts
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
- F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
- F16H25/20—Screw mechanisms
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
- F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
- F16H25/20—Screw mechanisms
- F16H25/22—Screw mechanisms with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
- F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
- F16H25/20—Screw mechanisms
- F16H25/22—Screw mechanisms with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members
- F16H25/2247—Screw mechanisms with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members with rollers
- F16H25/2252—Planetary rollers between nut and screw
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K7/00—Arrangements for handling mechanical energy structurally associated with dynamo-electric machines, e.g. structural association with mechanical driving motors or auxiliary dynamo-electric machines
- H02K7/003—Couplings; Details of shafts
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
- F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
- F16H25/20—Screw mechanisms
- F16H2025/2062—Arrangements for driving the actuator
- F16H2025/2075—Coaxial drive motors
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
- F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
- F16H25/20—Screw mechanisms
- F16H2025/2062—Arrangements for driving the actuator
- F16H2025/2087—Arrangements for driving the actuator using planetary gears
Definitions
- the present invention relates to a linear actuator.
- a linear motion actuator that includes an electric motor, a speed reduction mechanism, and a linear motion conversion mechanism, as seen in Patent Document 1.
- a screw mechanism including a rotatable nut and a threaded shaft that linearly moves in the direction of extension of the rotation axis of the nut according to the rotation of the nut is adopted as the linear motion conversion mechanism.
- a planetary gear mechanism is employed as a reduction mechanism.
- the sun gear of the planetary gear mechanism is connected to the electric motor, and each planetary gear of the planetary gear mechanism is pivotally supported by the nut of the linear motion conversion mechanism.
- the linear motion actuator of the document includes a shaft alignment plate having holes through which the gear shafts of the sun gear and each planetary gear are inserted.
- the plate aligns the revolution shaft of each planetary gear with the rotation shaft of the sun gear.
- the coaxiality of the rotation shafts of the electric motor and the linear motion conversion mechanism may be required.
- the plate for axial alignment of the above-mentioned conventional linear motion actuator performs axial alignment between the rotating shaft of the sun gear of the planetary gear mechanism and the revolution shaft of the planetary gear.
- Such a plate can only indirectly align the rotary shafts of the electric motor and the direct-acting conversion mechanism. Therefore, there is a possibility that the precision of alignment of the rotating shafts of the electric motor and the linear motion conversion mechanism cannot be sufficiently ensured.
- a linear motion actuator for solving the above problems includes a linear motion conversion mechanism and an electric motor.
- the direct-acting conversion mechanism includes one of a screw shaft and a nut screwed onto the screw shaft as a rotatable rotating member, and the other as a direct-acting member that moves linearly according to the rotation of the rotating member.
- the electric motor has a rotor that rotates coaxially with the rotating member. The electric motor rotates the rotating member according to the rotation of the rotor.
- the linear actuator includes a shaft member connected to the rotor so as to rotate together with the rotor. A shaft member is inserted into the threaded shaft of the linear motion actuator to form a hole for aligning the rotating shaft of the rotating member and the rotating shaft of the rotor.
- the axis of rotation of the rotating member and the axis of rotation of the rotor are aligned by inserting the shaft material into the hole provided in the screw shaft.
- the shaft member inserted into the hole of the screw shaft is connected to the rotor of the electric motor so as to rotate together. Therefore, direct shaft alignment between the electric motor and the linear motion conversion mechanism is possible. Therefore, according to the linear motion actuator, it is possible to easily and highly accurately align the axes of the electric motor and the linear motion conversion mechanism.
- FIG. 1 is a cross-sectional view of an electric cylinder provided with an embodiment of a linear actuator; FIG. Sectional drawing which shows the state at the time of assembly of the linear motion actuator.
- the schematic of the shaft alignment structure with which the modification 3 of a linear-acting actuator is provided.
- FIG. FIG. 11 is a cross-sectional view of an electric cylinder provided with a linear motion actuator according to Modification 4;
- FIG. A direct-acting actuator 20 of the present embodiment is provided in an electric cylinder 10 that generates hydraulic pressure that is converted into braking force in a braking device of a vehicle, for example.
- the electric cylinder 10 includes a cylinder 14 and a piston 15 that slides inside the cylinder 14 .
- the sliding direction of the piston 15 within the cylinder 14 is referred to as stroke direction S.
- a fluid chamber 16 filled with brake fluid is defined in the cylinder 14 by a piston 15 .
- the electric cylinder 10 presses the brake fluid in the fluid chamber 16 by the operation of the piston 15, thereby generating fluid pressure that is converted into braking force.
- a groove 17 extending in the sliding direction of the piston 15 is formed in the side wall of the cylinder 14 .
- a projection 18 formed on the piston 15 is engaged with the groove 17 . The engagement between the groove 17 and the projection 18 prevents the rotation of the piston 15 within the cylinder 14 .
- the electric cylinder 10 is roughly composed of two units, a cylinder unit 11 and a motor unit 12 .
- the electric cylinder 10 is manufactured by individually assembling the cylinder unit 11 and the motor unit 12 and then assembling them together. Note that the cylinder 14 and the piston 15 described above are provided in the cylinder unit 11 .
- the electric cylinder 10 is provided with a direct acting actuator 20 for driving the piston 15 .
- the linear motion actuator 20 includes an electric motor 21 , a reduction mechanism 22 and a linear motion conversion mechanism 23 .
- the speed reduction mechanism 22 and the linear motion conversion mechanism 23 are provided in the cylinder unit 11, and the electric motor 21 is provided in the motor unit 12, respectively.
- the motor unit 12 is provided with a control board 36 for power control of the electric motor 21 . It should be noted that the electric motor 21, the speed reduction mechanism 22, and the linear motion conversion mechanism 23 are arranged in series in the stroke direction S when the cylinder unit 11 and the motor unit 12 are assembled together.
- the direct-acting conversion mechanism 23 is a screw mechanism having a screw shaft 24 and a nut 25 screwed onto the screw shaft 24 .
- a ball screw mechanism in which a ball circulation mechanism is built in the nut 25 is adopted as the linear motion converting mechanism 23 .
- the screw shaft 24 is attached to the case 13 of the cylinder unit 11 while being rotatably supported by bearings 26 .
- the nut 25 is connected with the piston 15 so as to slide in the stroke direction S together.
- the linear motion converting mechanism 23 converts rotation of the screw shaft 24 into linear motion of the nut 25 in the stroke direction S. As shown in FIG.
- the electric motor 21 includes a stator 27 fixed to the case 19 of the motor unit 12 and a rotor 28 arranged radially inside the stator 27 .
- a motor shaft 29, which is a cylindrical shaft member, is coaxially connected to the rotor 28 so as to rotate together.
- the motor shaft 29 is positioned on the rotation axis O ⁇ b>2 of the rotor 28 and is a shaft member extending along the rotation axis O ⁇ b>2 of the rotor 28 .
- the motor shaft 29 is attached to the case 19 of the motor unit 12 while being rotatably supported by bearings 30 and 31 . A part of the motor shaft 29 protrudes from the case 19 in the direction in which the cylinder unit 11 is positioned when viewed from the motor unit 12 .
- the deceleration mechanism 22 is a mechanism that decelerates the rotation of the rotor 28 of the electric motor 21 and transmits it to the screw shaft 24 of the linear motion converting mechanism 23 .
- a planetary gear mechanism is adopted as the reduction mechanism 22 .
- the reduction mechanism 22 includes a sun gear 32 which is an external gear, a ring gear 33 which is an internal gear arranged radially outside the sun gear 32, and a plurality of gears interposed between the sun gear 32 and the ring gear 33. of planetary gears 34;
- a motor shaft 29 is inserted through the sun gear 32 .
- the sun gear 32 and the motor shaft 29 are connected by spline engagement or the like so as to rotate together.
- each planetary gear 34 is rotatably attached to the screw shaft 24 . That is, in the linear motion actuator 20, the screw shaft 24 also functions as a planetary carrier of the planetary gear mechanism.
- a hole 35 is formed in the screw shaft 24 from the end face of the screw shaft 24 on which the speed reduction mechanism 22 is located.
- the hole 35 is a round hole located on the rotation axis O1 of the screw shaft 24 and extending along the rotation axis O1 of the screw shaft 24 .
- the inner diameter of the hole 35 is approximately the same as the outer diameter of the motor shaft 29 .
- the tip of the motor shaft 29 is inserted into the hole 35 when the cylinder unit 11 and the motor unit 12 are assembled together.
- the inner diameter of the hole 35 is approximately the same as the outer diameter of the motor shaft 29 . Therefore, the hole 35 at this time is in sliding contact with the tip portion of the inserted motor shaft 29 .
- the rotation of the electric motor 21 is reduced by the reduction mechanism 22 and transmitted to the screw shaft 24 of the linear motion conversion mechanism 23 .
- the rotation of the screw shaft 24 is converted into a linear motion of the nut 25 in the linear motion converting mechanism 23 .
- the linear motion of the nut 25 causes the piston 15 to move in the stroke direction S within the cylinder 14 . It should be noted that a speed difference occurs in the rotation of the motor shaft 29 and the screw shaft 24 at this time.
- the electric motor 21 is installed in the motor unit 12 among the three elements of the linear motion actuator 20 , namely the electric motor 21 , the reduction mechanism 22 , and the linear motion conversion mechanism 23 .
- the remaining two speed reduction mechanisms 22 and direct-acting conversion mechanisms 23 are installed in the cylinder unit 11 .
- the electric cylinder 10 is manufactured by assembling the cylinder unit 11 and the motor unit 12 together. In such a linear motion actuator 20, if the rotation axis O1 of the screw shaft 24 of the linear motion converting mechanism 23 and the rotation axis O2 of the rotor 28 of the electric motor 21 are out of alignment, the linear motion actuator 20 can be smoothly operated. stop working. Therefore, when the cylinder unit 11 and the motor unit 12 are integrally assembled, the rotation axis O1 of the screw shaft 24 and the rotation axis O2 of the rotor 28 need to be aligned.
- FIG. 2 shows the assembled state of the cylinder unit 11 and the motor unit 12 in the electric cylinder 10 .
- the tip portion of the motor shaft 29 is inserted through the sun gear 32 and inserted into the hole 35 provided in the screw shaft 24 .
- the inner diameter of this hole 35 is approximately the same as the outer diameter of the tip portion of the motor shaft 29 . Therefore, the hole 35 and the motor shaft 29 are coaxial when the tip portion is inserted.
- the hole 35 is formed so as to be coaxial with the rotation axis O1 of the screw shaft 24 .
- the motor shaft 29 is coaxially connected to the rotor 28 so as to rotate together.
- the rotation axis O1 of the screw shaft 24 and the rotation axis O2 of the rotor 28 are aligned.
- the alignment between the electric motor 21 and the linear motion conversion mechanism 23 can be performed easily and with high accuracy.
- the linear motion conversion mechanism 23 is configured such that the nut 25 is linearly moved according to the rotation of the screw shaft 24 .
- the direct-acting conversion mechanism 23 is configured so that the screw shaft 24 moves linearly according to the rotation of the nut 25, the screw shaft 24 moves in the stroke direction S during the assembly work. Therefore, there is a possibility that the tip portion of the motor shaft 29 may come off from the hole 35 . If assembly is performed in this state, coaxiality between the rotation axis O1 of the screw shaft 24 and the rotation axis O2 of the rotor 28 cannot be obtained. In contrast, in the case of this embodiment, the screw shaft 24 does not move in the stroke direction S during the assembly work. Therefore, the direct-acting conversion mechanism 23 and the electric motor 21 can be aligned more reliably.
- the linear motion conversion mechanism 23 when the linear motion conversion mechanism 23 is configured so that the screw shaft 24 linearly moves according to the rotation of the nut 25, the screw shaft 24 moves in the stroke direction S according to the operation of the linear motion actuator 20. Moving. As the screw shaft 24 moves, the tip portion of the motor shaft 29 moves in and out of the hole 35 of the screw shaft 24 . When entering and exiting, the motor shaft 29 may not be properly inserted into the hole 35 and the screw shaft 24 and the motor shaft 29 may interfere with each other.
- the linear motion conversion mechanism 23 of the present embodiment is configured such that the nut 25 linearly moves according to the rotation of the screw shaft 24 . Therefore, the state in which the motor shaft 29 is inserted into the hole 35 is maintained even during the operation of the linear actuator 20 . Therefore, interference between the screw shaft 24 and the motor shaft 29 as described above does not occur when the linear motion actuator 20 is operated.
- the screw shaft 24 corresponds to the rotating member
- the nut 25 corresponds to the linear motion member
- the hole 35 provided in the screw shaft 24 and the motor shaft 29 constitute a shaft alignment structure for aligning the rotation axis O1 of the screw shaft 24 and the rotation axis O2 of the rotor 28 .
- the motor shaft 29 corresponds to the shaft material in the shaft alignment structure.
- the motor shaft 29 is connected to the sun gear 32 of the speed reduction mechanism 22 in the linear motion actuator 20 of the present embodiment.
- the screw shaft 24 constitutes a planetary carrier of the speed reduction mechanism 22 . That is, the threaded shaft 24 functionally has a structure in which the rotating member of the linear motion conversion mechanism 23 and the planetary carrier of the reduction mechanism 22 are integrally connected.
- the rotation axis O1 of the screw shaft 24 and the rotation axis of the motor shaft 29 are aligned by inserting the motor shaft 29 into the hole 35 provided in the screw shaft 24.
- the shaft alignment structure in the linear motion actuator 20 of the present embodiment includes alignment of the rotation shafts of the electric motor 21 and the linear motion conversion mechanism 23, and also of the rotation shaft of the sun gear 32 of the reduction mechanism 22 and the planetary gear 34. Alignment with the revolution axis is also performed.
- the motor shaft 29 that transmits the rotation of the rotor 28 of the electric motor 21 to the sun gear 32 extends from the sun gear 32 toward the linear motion converting mechanism 23 .
- the motor 21 and the linear motion converting mechanism 23 are aligned. That is, the motor shaft 29 is formed as an integral part including a portion inserted into the hole 35 for shaft alignment.
- the part to be inserted into the hole 35 for such shaft alignment may be a separate part from the motor shaft 29 .
- the portion inserted into the hole 35 at this time is a shaft member as follows.
- this shaft member is located on the rotation axis O2 of the rotor 28 and extends along the rotation axis O2 of the rotor 28, and is a shaft member that rotates integrally with the rotor 28.
- motor shaft 29 is the length from rotor 28 to sun gear 32 .
- a metal pin that can be inserted into the hole 35 of the screw shaft 24 is connected to the tip of the motor shaft 29 so as to rotate together with the motor shaft 29 .
- the axes of the electric motor 21 and the linear motion conversion mechanism 23 are aligned according to the insertion of the metal pin into the hole 35 .
- the speed reduction mechanism 22 reduces the speed of rotation of the rotor 28 of the electric motor 21 and transmits it to the screw shaft 24 . Therefore, the screw shaft 24 rotates relative to the motor shaft 29 when the linear motion actuator 20 is actuated.
- the linear motion actuator 20 of the above-described embodiment by inserting the tip portion of the motor shaft 29 into the hole 35 provided in the screw shaft 24, the motor 21 and the direct motion conversion mechanism 23 are aligned. . To increase the degree of coaxiality between them, it is necessary to tighten the fit of the tip portion of the motor shaft 29 in the hole 35 .
- the threaded shaft 40 of the linear motion actuator 20 of Modification 1 includes a base material 41 made of metal and a resin bush 43 that is a bush made of resin.
- a bush mounting hole 42 is formed in the base material 41 from the end face on the side where the speed reduction mechanism 22 is located when viewed from the screw shaft 40 .
- a resin bush 43 is mounted in the bush mounting hole 42 .
- the resin bushing 43 is formed with a through hole 44 extending in the extending direction of the rotation axis O ⁇ b>1 of the screw shaft 40 .
- the rotation axis O1 of the screw shaft 40 and the rotation axis O2 of the rotor 28 are aligned by inserting the motor shaft 29 into the through hole 44 . That is, the through hole 44 of the resin bushing 43 provided in the screw shaft 40 corresponds to the hole of the shaft alignment structure, and the motor shaft 29 corresponds to the shaft member of the coaxial alignment structure.
- the contact surface of the hole with the shaft member is made of a resin material, while the contact surface of the shaft member with the hole is made of a metal material.
- the tip portion of the motor shaft 29 is in sliding contact with the resin bushing 43 .
- the surface of the through hole 44 of the resin bushing 43 made of resin has a lower hardness than the motor shaft 29 made of metal and is easily worn. Therefore, when the linear motion actuator 20 operates and the screw shaft 40 and the motor shaft 29 rotate relative to each other, the wear of the surface of the through hole 44 in the resin bushing 43 progresses, causing the motor shaft 29 and the through hole 44 to slide. resistance decreases. Therefore, by adopting the shaft alignment structure of Modification 1, it is possible to both improve the accuracy of the shaft alignment and facilitate the operation of the linear motion actuator 20 .
- a motor shaft 50 that constitutes the shaft member of the shaft alignment structure in Modification 2 is composed of a metal base 51 and a resin ring 52 attached to the tip of the base 51. It is configured.
- the base material 51 is a cylindrical member extending in the stroke S direction.
- the resin ring 52 is a hollow cylindrical member made of resin.
- the outer diameter of the resin ring 52 is approximately the same as the inner diameter of the hole 35 of the screw shaft 24 .
- the contact surface of the hole 35 with the motor shaft 50 is made of a metal material, and the contact surface of the motor shaft 50 with the hole 35 is made of a resin material.
- one of the contact surface of the hole with the shaft material and the contact surface of the shaft material with the hole is made of metal, while the resin having a hardness lower than that of the metal is used. form the other.
- the contact surface having a lower hardness and being more easily worn gradually wears away thereby reducing the sliding resistance of both contact surfaces. do. Therefore, it is possible to achieve both the improvement of the accuracy of the shaft alignment and the smooth operation of the linear motion actuator 20 .
- a combination other than resin and metal may be adopted as long as it is a combination of materials having different hardnesses.
- Modification 3 The configuration of Modified Example 3 of the shaft alignment structure of the linear actuator 20 will be described with reference to FIGS. 5 and 6.
- FIG. 5 As shown in FIG. 5, in the shaft alignment structure of Modification 3, a metal pin 61, which is a metal pin attached to the tip of the motor shaft 29, is inserted into the hole 35 of the screw shaft 24 for shaft alignment. and
- the metal pin 61 is integrated with the motor shaft 60 by resin insert molding. That is, the metal pin 61 is connected to the motor shaft 60 via a resin portion 63 which is a portion made of resin.
- the metal pin 61 has a cylindrical portion with the same outer diameter as the motor shaft 60 .
- a spline 62 is formed on the side circumference of the cylindrical portion of the metal pin 61 .
- the extending direction of the spline 62 is the extending direction of the rotation axis of the motor shaft 60, that is, the extension of the rotation axis O2 of the rotor 28 of the electric motor 21 to which the motor shaft 60 is coaxially connected so as to rotate together. direction.
- the screw shaft 24 is provided with a hole 64 into which the metal pin 61 can be inserted.
- a side wall of the hole 64 is formed with a spline 65 that can be engaged with the spline 62 of the metal pin 61 .
- a torsional torque T is generated between the screw shaft 24 and the motor shaft 60 .
- the torsional torque T breaks the joint between the motor shaft 60 or the metal pin 61 and the resin portion 63 .
- the joint between the metal pin 61, the motor shaft 60, and the resin portion 63 is a fragile portion that breaks according to relative rotation between the rotor 28 and the screw shaft 24 as the electric motor 21 operates.
- the metal pin 61 that constitutes the shaft member of the shaft alignment structure of Modification 3 is connected to the rotor 28 via such a fragile portion. 6 shows a state in which the joint between the motor shaft 60 and the resin portion 63 is broken.
- the linear motion actuator 20 of the above-described embodiment employs the linear motion conversion mechanism 23 configured such that the nut 25 linearly moves according to the rotation of the screw shaft 24 .
- a linear motion conversion mechanism may be employed in which the screw shaft linearly moves according to the rotation of the nut.
- FIG. 7 shows a cross-sectional structure of an electric cylinder 110 provided with a linear motion actuator 120 that employs such a linear motion conversion mechanism 123 .
- the configurations of the electric motor 21 and the speed reduction mechanism 22 in the linear motion actuator 120 are the same as those of the above embodiment.
- a linear motion conversion mechanism 123 in the linear motion actuator 120 includes a nut 125 rotatably attached to the case 13 by a bearing 26 and a screw shaft 124 screwed onto the nut 125 . In such a linear motion converting mechanism 123 , the screw shaft 124 linearly moves according to the rotation of the nut 125 .
- a piston 115 in the electric cylinder 110 is connected to a screw shaft 124 so as to move in the stroke direction S together.
- each planetary gear 34 of the speed reduction mechanism 22 is rotatably attached to a nut 125 instead of a screw shaft 124. As shown in FIG. That is, in the linear motion actuator 120, the nut 125 also functions as a planetary carrier of the planetary gear mechanism.
- the screw shaft 124 is formed with a hole 35 into which the tip portion of the motor shaft 60 can be inserted.
- the rotation axis O1 of the nut 125 of the linear motion conversion mechanism 123 and the rotation axis O2 of the rotor 28 of the electric motor 21 are aligned. Therefore, in such a linear motion actuator 120 as well, the axis alignment between the electric motor 21 and the linear motion conversion mechanism 123 can be performed easily and with high accuracy.
- the linear motion actuator 120 the movement of the screw shaft 124 in the extending direction of the rotation axis O1 of the nut 125 is allowed. Therefore, it is desirable that the motor 21 and the linear motion conversion mechanism 123 are aligned while the movement of the screw shaft 124 is restricted.
- the ball screw mechanism was adopted as the linear motion conversion mechanism 23, 123. If the screw mechanism has a screw shaft and a nut screwed onto the screw shaft, and one of them moves linearly according to the rotation of the other, a mechanism other than the ball screw mechanism is used as the linear motion conversion mechanism 23, 123 may be employed.
- a screw mechanism that can be employed as the linear motion converting mechanisms 23 and 123 includes a feed screw mechanism in which a screw shaft and a nut are directly screwed together without a ball.
- a planetary gear mechanism is employed as the speed reduction mechanism 22 in the above-described embodiment and modifications.
- a mechanism other than the planetary gear mechanism may be employed as the reduction mechanism 22 .
- Mechanisms that can be employed as the reduction mechanism 22 include a cycloid reduction gear, a paradox gear, and a worm gear.
- the direct acting actuators 20 and 120 may be configured such that the electric motor 21 and the direct acting conversion mechanisms 23 and 123 are directly connected without providing the speed reduction mechanism 22 .
- linear actuators 20 and 120 ⁇ Regarding applications of linear actuators 20 and 120>
- the direct-acting actuators 20, 120 of the above embodiments and modifications are used as actuators for driving the pistons 15, 115 of the electric cylinders 10, 110.
- the linear motion actuators 20 and 120 of the above embodiments and modifications can also be used for other applications.
- the structure related to the shaft alignment between the screw shaft 24 and the rotor 28 in the above-described embodiment and Modifications 1 to 3 can be used for shaft alignment between two rotating bodies that rotate relative to each other.
- one of the two rotating bodies is the first rotating body, and the other is the second rotating body.
- the following shaft member is provided as a shaft alignment structure for these two rotating bodies. This shaft member is located on the rotation axis of the first rotor and extends along the rotation axis of the first rotor, and rotates integrally with the first rotor. It is wood. Also, the following holes are provided in the second rotor.
- This hole is a hole located on the rotation axis of the second rotor and extending along the rotation axis of the second rotor.
- the hole is a hole into which the tip portion of the shaft member can be inserted, and which is in sliding contact with the tip portion of the coaxial member when the tip portion is inserted.
- the shaft alignment structure can be configured according to Modification 1 above. That is, a bush made of resin is attached to the base material of the second rotating body. A hole into which the shaft member is inserted is provided in the resin bush. In such a case, when the rotating bodies are rotated relative to each other after the shafts are aligned, the hole of the resin bush rubs against the shaft member inserted into the hole, and the surface of the hole of the resin bush is worn. The wear reduces the sliding resistance between the hole and the shaft member. Therefore, even if the fitting between the shaft member and the hole is tight in order to increase the degree of coaxiality between the two rotating bodies, the two rotating bodies can be smoothly rotated relative to each other.
- the shaft alignment structure can be configured according to Modification 2 above. That is, the sliding contact surface of the shaft member inserted into the hole of the second rotating body and the same hole is formed of resin.
- the sliding contact surface of the shaft member made of resin is worn due to friction with the hole, and the sliding resistance between the hole and the shaft member is reduced. Therefore, even if the fitting between the shaft member and the hole is tight in order to increase the degree of coaxiality between the two rotating bodies, the two rotating bodies can be smoothly rotated relative to each other.
- a shaft alignment structure for aligning the first and second rotating bodies which are two rotatably installed rotating bodies that rotate relative to each other, wherein the first rotating body A shaft member positioned on the rotation shaft and extending along the rotation axis of the first rotor, the shaft member rotating integrally with the first rotor, and the second the rotating body has a hole positioned on the rotating shaft of the second rotating body and extending along the rotating shaft of the second rotating body, wherein the tip portion of the shaft member can be inserted; and a shaft alignment structure for a rotating body, in which a hole is provided for slidably contacting the tip portion of the shaft member when the tip portion is inserted.
- the second rotary body has a metal base material and a resin bush attached to the base material, and the hole is provided in the bush. ).
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Power Engineering (AREA)
- Transmission Devices (AREA)
- Connection Of Motors, Electrical Generators, Mechanical Devices, And The Like (AREA)
Abstract
Description
まず、図1を参照して電動シリンダ10の構成を説明する。電動シリンダ10は、シリンダ14と、シリンダ14内を摺動するピストン15と、を備えている。以下の説明では、シリンダ14内でのピストン15の摺動方向を、ストローク方向Sと記載する。シリンダ14内には、ブレーキ液が充填される液室16がピストン15により区画形成されている。電動シリンダ10は、ピストン15の作動により液室16内のブレーキ液を押圧することで、制動力に転換される液圧を発生する。シリンダ14の側壁には、ピストン15の摺動方向に延びる溝17が形成されている。溝17には、ピストン15に形成された突起18が係合されている。そして、溝17と突起18との係合により、シリンダ14内でのピストン15の回り止めがなされている。
電動シリンダ10には、ピストン15を駆動するための直動アクチュエータ20が設けられている。直動アクチュエータ20は、電動機21と、減速機構22と、直動変換機構23と、を備えている。これらのうち、減速機構22及び直動変換機構23はシリンダユニット11に、電動機21はモータユニット12に、それぞれ設けられている。また、モータユニット12には、電動機21の電力制御のための制御基板36が設けられている。なお、シリンダユニット11及びモータユニット12を一体に組付けた状態において、電動機21、減速機構22、及び直動変換機構23は、ストローク方向Sに直列に並んだ配置となる。
上記のように構成された本実施形態の直動アクチュエータ20の作用及び効果について説明する。
本実施形態は、以下のように変更して実施することができる。本実施形態及び以下の変更例は、技術的に矛盾しない範囲で互いに組み合わせて実施することができる。
上記実施形態では、電動機21の回転子28の回転をサンギア32に伝えるモータシャフト29が、サンギア32よりも直動変換機構23側に延長されていた。そして、その延長したモータシャフト29の先端部分を、ねじ軸24に設けた穴35に挿入することで、電動機21と直動変換機構23との軸合せを行っていた。すなわち、軸合せに際して穴35に挿入される部分を含む一体の部品としてモータシャフト29が形成されていた。このような軸合せに際して穴35に挿入される部分をモータシャフト29と別部品としてもよい。このときの穴35に挿入される部分は、次のような軸材となる。すなわち、この軸材は、回転子28の回転軸O2上に位置して回転子28の回転軸O2に沿って延びる軸材であって、回転子28と一体となって回転する軸材となる。例えば、モータシャフト29を、回転子28からサンギア32までの長さとする。そして、ねじ軸24の穴35に挿入可能な金属ピンをモータシャフト29の先端に、モータシャフト29と一体となって回転するように連結する。こうした場合にも、金属ピンの穴35への挿入に応じて電動機21と直動変換機構23との軸合せが行われる。
図3を参照して、直動アクチュエータ20の軸合せ構造の変形例1の構成を説明する。変形例1の直動アクチュエータ20のねじ軸40は、金属製の基材41と、樹脂製のブッシュである樹脂ブッシュ43と、を備えている。基材41には、ねじ軸40から見て減速機構22が位置する側の端面より穿たれたブッシュ取付穴42が形成されている。そして、樹脂ブッシュ43がそのブッシュ取付穴42に装着されている。樹脂ブッシュ43には、ねじ軸40の回転軸O1の延伸方向に抜ける通孔44が形成されている。そして、シリンダユニット11とモータユニット12との組付けに際しては、その通孔44内にモータシャフト29の先端部分が挿入される。ちなみに樹脂ブッシュ43の通孔44に先端部分が挿入されるモータシャフト29は、金属製である。
図4を参照して、直動アクチュエータ20の軸合せ構造の変形例2の構成を説明する。図4に示すように、変形例2における軸合せ構造の軸材を構成するモータシャフト50は、金属製の基材51と、その基材51の先端部分に取り付けられた樹脂リング52と、により構成されている。基材51は、ストロークS方向に延びる円柱形状の部材である。樹脂リング52は、樹脂製の中空円筒形状の部材である。なお、樹脂リング52の外径は、ねじ軸24の穴35の内径とほぼ同じ径とされている。こうした変形例2では、穴35におけるモータシャフト50との接触面が金属材料により形成されるとともに、モータシャフト50における穴35との接触面が樹脂材料により形成されている。
図5及び図6を参照して、直動アクチュエータ20の軸合せ構造の変形例3の構成を説明する。図5に示すように、変形例3の軸合せ構造では、モータシャフト29の先端に取り付けられた金属製のピンである金属ピン61を、軸合せに際してねじ軸24の穴35に挿入する軸材としている。
上記実施形態の直動アクチュエータ20では、ねじ軸24の回転に応じてナット25が直動する構成の直動変換機構23を採用していた。これとは逆に、ナットの回転に応じてねじ軸が直動する直動変換機構を採用してもよい。
上記実施形態及び変形例では、遊星ギア機構を減速機構22として採用していた。遊星ギア機構以外の機構を減速機構22として採用してもよい。減速機構22として採用可能な機構としては、サイクロイド減速機や、不思議歯車、ウォームギアがある。また、減速機構22を設けずに、電動機21と直動変換機構23、123とを直接連結するように、直動アクチュエータ20、120を構成してもよい。
上記実施形態及び変形例の直動アクチュエータ20、120は、電動シリンダ10、110のピストン15、115を駆動するアクチュエータとして使用されていた。上記実施形態及び変形例の直動アクチュエータ20、120は、それ以外の用途にも利用可能である。
上記実施形態及び変形例1~3におけるねじ軸24と回転子28との軸合せに係る構造は、それ以外の、互いに相対回転する2つの回転体の間の軸合せに利用できる。ここでは、2つの回転体のうちの一方を第1の回転体とし、もう一方を第2の回転体とする。これら2つの回転体の軸合せ構造として、次の軸材を設ける。この軸材は、第1の回転体の回転軸上に位置して該第1の回転体の回転軸に沿って延びる軸材であって、第1の回転体と一体となって回転する軸材である。また、第2の回転体に、次の穴を設ける。この穴は、第2の回転体の回転軸上に位置して該第2の回転体の回転軸に沿って延びる穴である。そして、同穴は、軸材の先端部分が挿入可能であり、かつ同軸材の先端部分が挿入された状態において同先端部分と摺接する穴である。こうした穴に上記軸材が挿入された状態では、第1の回転体の回転軸と第2の回転体の回転軸とが軸合せされた状態となる。そのため、第2の回転体に設けられた穴への軸材の挿入を通じて、第1の回転体と第2の回転体との直接の軸合せが可能となる。したがって、上記のような軸合せ構造によれば、電動機及び直動変換機構間の容易かつ高精度の軸合せが可能となる。
次に、上記実施形態及び変更例から把握できる技術的思想について記載する。
(イ)回転自在に設置された2つの回転体であって、互いに相対回転する第1及び第2の回転体の軸合せを行うための軸合せ構造であって、前記第1の回転体の回転軸上に位置して該第1の回転体の回転軸に沿って延びる軸材であって、前記第1の回転体と一体となって回転する軸材を備えており、かつ前記第2の回転体には、該第2の回転体の回転軸上に位置して該第2の回転体の回転軸に沿って延びる穴であって、前記軸材の先端部分が挿入可能であり、かつ前記軸材の先端部分が挿入された状態において同先端部分と摺接する穴が設けられている回転体の軸合せ構造。
(ニ)前記軸材は、前記電動機の作動に伴う前記回転子と前記ねじ軸との相対回転に応じて破断する脆弱部を介して前記回転子に連結されている請求項1~請求項4のいずれか1項に記載の直動アクチュエータ。
Claims (4)
- ねじ軸及び同ねじ軸に螺合したナットの一方を回転自在な回転部材として備えるとともに、他方を前記回転部材の回転に応じて直動する直動部材として備える直動変換機構と、
前記回転部材と同軸を有して回転する回転子を備える電動機であって、同回転子の回転に応じて前記回転部材を回転させる電動機と、
前記回転子と一体となって回転するように同回転子に連結された軸材と、
を備えており、かつ
前記軸材が挿入されることで、前記回転部材の回転軸と前記回転子の回転軸との軸合せを行う穴が前記ねじ軸に設けられている
直動アクチュエータ。 - 前記ねじ軸が前記回転部材であり、前記ナットが前記直動部材である請求項1に記載の直動アクチュエータ。
- 前記回転子の回転を減速して前記回転部材に伝達する機構であって、前記軸材に連結されたサンギアと、前記回転部材に連結されたプラネタリキャリアと、を有した遊星ギア機構を備える請求項1又は請求項2に記載の直動アクチュエータ。
- 前記穴における前記軸材との接触面、及び前記軸材における前記穴との接触面のうちの一方は、他方よりも硬度が高い請求項1~請求項3のいずれか1項に記載の直動アクチュエータ。
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CN202280046477.6A CN117581459A (zh) | 2021-07-02 | 2022-06-28 | 直动促动器 |
DE112022003385.1T DE112022003385T5 (de) | 2021-07-02 | 2022-06-28 | Linearstellglied |
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Citations (3)
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JPH07241065A (ja) * | 1994-02-25 | 1995-09-12 | Fuji Elelctrochem Co Ltd | リードスクリュー型ステッピングモータ |
JP2006174690A (ja) * | 2004-11-18 | 2006-06-29 | Smc Corp | アクチュエータ制御システム |
JP2018105434A (ja) * | 2016-12-27 | 2018-07-05 | Ntn株式会社 | 電動アクチュエータ |
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FR3037839B1 (fr) * | 2015-06-24 | 2017-12-08 | Pellenc Sa | Outil electroportatif a reducteur epicycloidal |
DE102015214584A1 (de) | 2015-07-31 | 2017-02-02 | Robert Bosch Gmbh | Rotations/Translations-Wandlergetriebe |
US11384820B2 (en) * | 2018-01-11 | 2022-07-12 | Linak A/S | Linear actuator |
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Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
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JPH07241065A (ja) * | 1994-02-25 | 1995-09-12 | Fuji Elelctrochem Co Ltd | リードスクリュー型ステッピングモータ |
JP2006174690A (ja) * | 2004-11-18 | 2006-06-29 | Smc Corp | アクチュエータ制御システム |
JP2018105434A (ja) * | 2016-12-27 | 2018-07-05 | Ntn株式会社 | 電動アクチュエータ |
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JP2023007796A (ja) | 2023-01-19 |
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