Linear actuator

Abstract

To provide a linear actuator capable of suppressing sudden operation of a linear motion mechanism part when a trouble occurs.SOLUTION: A linear actuator 10 has a drive gear 22 provided in a revolving shaft 21 of a motor 20, a transmission gear group 23, a linear motion mechanism part 30, and a cover 12. The transmission gear group 23 has a first transmission gear 24, and further has a brake disc 40 connected to the first transmission gear 24 rotatably together, a magnet holder 42 facing the brake disc 40 and fixed and provided to the cover 12, and a plurality of magnets 43 arranged in the magnet holder 42.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a linear actuator. [Background technology]

[0002] A known example of a conventional linear actuator used in aircraft is the linear actuator described in Patent Document 1. This linear actuator has a linear motion mechanism that converts the driving force of an electric motor into linear motion, and operates a movable part of the aircraft connected to the linear motion mechanism. For example, if the movable part of the aircraft is a cargo bay door that opens when lifted, the cargo bay door is lifted and opened by extending the linear motion mechanism of the linear actuator connected to the cargo bay door. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Registered Utility Model No. 3135267 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the linear actuator described in Patent Document 1 is a linear actuator capable of backdriving, there is a problem in that when a failure occurs in the linear actuator, the linear motion mechanism unit cannot maintain its extended state, causing the linear motion mechanism unit to suddenly shorten and the cargo door to suddenly drop.

[0005] The present invention has been made to solve such problems, and aims to provide a linear actuator that can suppress sudden movement of the linear motion mechanism when a failure occurs in the linear actuator. [Means for solving the problem]

[0006] In order to solve the above problems, the linear actuator of the present invention comprises a motor, a drive gear provided on the rotating shaft of the motor, a group of transmission gears connected to the drive gear and transmitting the rotational driving force of the drive gear, a linear motion mechanism connected to the group of transmission gears and moving linearly by the rotational driving force transmitted by the group of transmission gears, and a case that houses the motor, drive gear, group of transmission gears, and linear motion mechanism, wherein the group of transmission gears has at least one transmission gear, and the linear motion mechanism has a ball screw connected to the group of transmission gears, a nut threaded onto the ball screw, and a rod connected to the nut, and comprises a conductor disk rotatably connected to at least one of the rotating shaft of the transmission gear and the ball screw, a magnet holder facing the conductor disk and fixed to the case, and a plurality of permanent magnets arranged circumferentially on the magnet holder.

[0007] In addition, the permanent magnets may be arranged in the magnet holder along the circumferential direction of the conductive disk, with the north pole facing the conductive disk and the south pole facing the conductive disk alternately arranged at equal angular intervals. In addition, some of the permanent magnets may be arranged in the magnet holder along the circumferential direction of the conductive disk, with two or more consecutive north or south poles facing the conductive disk at equal angular intervals. In addition, the other permanent magnets may be arranged in the magnet holder along the circumferential direction of the conductive disk, with the north pole facing the conductive disk and the south pole facing the conductive disk alternately arranged at equal angular intervals. Furthermore, the permanent magnets may be arranged in the magnet holder along the circumferential direction of the conductive disk within a sector-shaped range having a central angle exceeding 180° and centered on the central axis of the conductive disk. The permanent magnets may be arranged in the magnet holder along the circumferential direction of the conductive disk within a sector having a central angle of 180° or less, centered on the central axis of the conductive disk. In addition, the magnet holder may have multiple accommodating holes formed at equal angular intervals along the circumferential direction of the conductor disk, and the permanent magnets may be accommodated in the accommodating holes, with at least one accommodating hole between adjacent permanent magnets that does not accommodate a permanent magnet. The permanent magnets may also include first permanent magnets arranged in the magnet holder at equal angular intervals on a first circumference centered on the central axis of the conductive disk, and second permanent magnets arranged in the magnet holder at equal angular intervals on a second circumference centered on the central axis and having a diameter smaller than the first circumference. In addition, the number of first permanent magnets and the number of second permanent magnets may be the same, and a virtual line extending from the center of each first permanent magnet to the central axis may overlap with a virtual line extending from the center of each second permanent magnet to the central axis. In addition, the number of first permanent magnets and the number of second permanent magnets may be the same, and a virtual line extending from the center of each first permanent magnet to the central axis may intersect with a virtual line extending from the center of each second permanent magnet to the central axis.

[0008] In addition, in order to solve the above-mentioned problems, the manufacturing method of the linear actuator of the present invention includes the steps of forming a first magnet holder on a first circumference centered on the central axis of a conductive disk, in which a plurality of accommodating holes for accommodating permanent magnets are formed; forming a second magnet holder on a second circumference centered on the central axis and having a diameter smaller than the first circumference, in which a plurality of accommodating holes for accommodating permanent magnets are formed; and selecting one magnet holder from the first magnet holder and the second magnet holder, accommodating a permanent magnet in the selected magnet holder, and fixing it to a case portion. [Effects of the Invention]

[0009] The linear actuator of the present invention has a linear motion mechanism unit which has a ball screw connected to a group of transmission gears which transmit the rotational driving force of the motor, a nut threaded onto the ball screw, and a rod connected to the nut, and is equipped with a conductor disk rotatably connected to at least one of the rotation shafts of each transmission gear of the transmission gear group and the ball screw, a magnet holder facing the conductor disk and fixed to the case unit, and multiple permanent magnets arranged circumferentially on the magnet holder, so that sudden movement of the linear motion mechanism unit can be suppressed when a malfunction occurs in the linear actuator. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a perspective view of a linear actuator according to a first embodiment of the present invention. [Figure 2] 1 is a partial front cross-sectional view of a linear actuator according to a first embodiment of the present invention. [Figure 3] 1 is a partial exploded view of a linear actuator according to a first embodiment of the present invention. [Figure 4] FIG. 2 is a diagram showing the arrangement of magnets according to the first embodiment of the present invention. [Figure 5] FIG. 10 is a diagram showing the arrangement of magnets according to the second embodiment of the present invention. [Figure 6] FIG. 10 is a diagram showing the arrangement of magnets according to a third embodiment of the present invention. [Figure 7] FIG. 10 is a diagram showing the arrangement of magnets according to a fourth embodiment of the present invention. [Figure 8] FIG. 10 is a diagram showing the arrangement of magnets according to a fifth embodiment of the present invention. [Figure 9] FIG. 10 is a diagram showing the arrangement of magnets according to a sixth embodiment of the present invention. [Figure 10] FIG. 13 is a diagram showing the arrangement of magnets according to a seventh embodiment of the present invention. [Figure 11] FIG. 13 is a diagram showing the arrangement of magnets according to an eighth embodiment of the present invention. [Figure 12] FIG. 13 is a diagram showing the arrangement of a first magnet according to a ninth embodiment of the present invention. [Figure 13] FIG. 13 is a diagram showing the arrangement of a second magnet according to a ninth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] Embodiment 1 A linear actuator according to a first embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a perspective view of a linear actuator 10 according to the first embodiment. The linear actuator 10 is a linear actuator provided on an aircraft, and includes a motor 20 housed inside a case 11 and a linear motion mechanism 30 that converts the rotational driving force of the motor 20 into linear motion. When the motor 20 is driven, a rod 31 of the linear motion mechanism 30 moves linearly and extends and contracts, and the extension and contraction of the rod 31 can open and close a cargo bay door, which is a movable part of the aircraft (not shown) and is connected to a rod tip 32. When the rod 31 extends, the cargo bay door is lifted and opened, and when the rod 31 retracts, the cargo bay door is lowered and closed.

[0012] The linear actuator 10 is a linear actuator capable of backdrive operation, which is an operation of extending and retracting the rod 31 by applying an external force to the rod 31. Furthermore, when the rod 31 is extended and the motor 20 is not driven, the linear motion mechanism 30 can hold the cargo door in an open state by fixing the rod 31 in the extended state using a locking mechanism (not shown).

[0013] 2 is a partial front cross-sectional view of the linear actuator 10 shown in FIG. A drive gear 22 that transmits the driving force of the motor is provided on a rotary shaft 21 of a motor 20. A transmission gear group 23 that transmits the rotational driving force of the drive gear 22 is connected to the drive gear 22. The transmission gear group 23 includes a first transmission gear 24 that meshes with the drive gear 22, a second transmission gear 25 that meshes with the first transmission gear 24, a third transmission gear 26 that is formed integrally and coaxially with the second transmission gear 25, and a fourth transmission gear 27 that meshes with the third transmission gear 26 and is provided coaxially with a ball screw 33 provided in the linear motion mechanism 30. The transmission gear group 23 is housed in a case 11 and a case end 11a that is connected to an end of the case 11.

[0014] The linear motion mechanism 30 has a ball screw 33. The ball screw 33 includes a rotatable screw shaft 34, a nut 35, and a rod 31 connected to the nut. The rotation of the fourth transmission gear 27 causes the screw shaft 34 of the ball screw 33 to rotate. The rotation of the screw shaft 34 causes the nut 35 to move linearly along the axial direction of the screw shaft 34, and the rod 31 connected to the nut 35 to move linearly and expand and contract. The linear motion mechanism 30 is housed in a case 11 and a case end 11a connected to an end of the case 11.

[0015] A brake disc 40 is attached to the rotating shaft 24a of the first transmission gear 24. The brake disc 40 is a circular plate made of aluminum, and rotates together with the rotating shaft 24a, with the rotating shaft 24a as its central axis. The brake disc 40 is also disposed inside a mounting portion 11b, which is formed in a cylindrical shape at the case end 11a of the case 11 so as to extend along the axial direction of the rotating shaft 24a.

[0016] The mounting portion 11b is provided with a cover 12 that fits onto the mounting portion 11b and covers the opening of the mounting portion 11b. A disk-shaped magnet base 41 made of a ferromagnetic material such as a steel plate is provided on the surface of the cover 12 that faces the brake disc 40. The case 11, case end 11a, mounting portion 11b, and cover 12 form the case portion of the linear actuator 10.

[0017] A disk-shaped magnet holder 42 made of a non-magnetic material such as resin, and a magnet 43 held by the magnet holder 42 are provided on the surface of the magnet base 41 facing the brake disc 40. The magnet holder 42 shares a central axis with the brake disc 40. The magnet holder 42 and the magnet 43 are arranged facing the brake disc 40 and not in contact with the brake disc 40. The magnet base 41 holds the magnets 43 by attracting them, and is also provided to form magnetic paths between the magnets 43 and reduce leakage magnetic flux of the magnets 43.

[0018] 3 is a partial exploded view of the linear actuator 10 shown in FIG. 2. The cover 12 is fixed to the mounting portion 11b with screws 13. The magnet holder 42 has a plurality of circular accommodating holes 42a formed along the circumferential direction. Each accommodating hole 42a accommodates a cylindrical magnet 43 that is formed so as to be able to fit into the accommodating hole 42a. A bearing 44 is attached to the rotating shaft 24a between the cover 12 and the brake disc 40.

[0019] FIG. 4 is a view of the surface of the magnet holder 42 shown in FIG. 2 that faces the brake disc 40, viewed from a direction along the rotation axis 24a, illustrating the arrangement of magnets according to the first embodiment. A total of 18 accommodating holes 42a are formed at equal angular intervals on a circumference of the same diameter from the center of the magnet holder 42. In FIG. 4, of the magnets 43 accommodated in each accommodating hole 42a, those arranged so that the side facing the brake disc 40 is the north pole are indicated by the symbol "N," and those arranged so that the side facing the brake disc 40 is the south pole are indicated by the symbol "S." The magnets 43 accommodated in each accommodating hole 42a are arranged so that the side facing the brake disc 40 is the north pole and the side facing the brake disc 40 is the south pole, alternately. In other words, the magnets 43 are arranged so that the polarity of adjacent magnets 43 in the circumferential direction is opposite to that of the adjacent magnets 43.

[0020] Next, the operation of the linear actuator 10 of the first embodiment will be described. In the linear actuator 10 shown in FIG. 2, when the motor 20 is driven by a control circuit (not shown), the rotation shaft 21 rotates, thereby rotating the drive gear 22. The rotation of the drive gear 22 transmits the driving force of the motor 20 to the first transmission gear 24, the second transmission gear 25, the third transmission gear 26, and the fourth transmission gear 27 in this order. Next, the fourth transmission gear 27 is driven, thereby rotating the screw shaft 34 of the ball screw 33. The rotation of the screw shaft 34 causes the nut 35 to move linearly along the axial direction of the screw shaft 34, and the rod 31 connected to the nut 35 moves linearly and expands and contracts. A cargo bay door of an aircraft is connected to a rod tip 32 (see FIG. 1) of the rod 31. The cargo bay door of the aircraft is lifted and opened when the rod 31 extends, and the cargo bay door is pulled down and closed when the rod 31 contracts.

[0021] Furthermore, when the rod 31 is extended and the cargo door is lifted, in order to maintain this state when the motor 20 is not driven, the linear motion mechanism unit 30 fixes the rod 31 in the extended state using a locking mechanism (not shown), thereby holding the cargo door in the open state.

[0022] If the locking mechanism fails when the motor 20 is not driven and the linear motion mechanism 30 has fixed the rod 31 in an extended state, the weight of the cargo door will cause the rod 31 to retract. Also, if the driving force of the motor 20 is no longer applied to the ball screw 33 due to a malfunction of the motor 20 or a loss of power supplied to the motor 20 while the motor 20 is driven, the weight of the cargo door will also cause the rod 31 to retract. In such cases, conventional linear actuators have had the problem of the rod 31 being rapidly retracted, causing the cargo door to rapidly descend.

[0023] On the other hand, in the first embodiment of the present application, if the locking mechanism fails when the motor 20 is not driven and the linear motion mechanism 30 has fixed the rod 31 in an extended state, or if the driving force of the motor 20 is no longer applied to the ball screw 33 due to a failure of the motor 20 or a loss of power supplied to the motor 20 while the linear actuator 10 is in operation, and the rod 31 is shortened by the weight of the cargo door, the nut 35 moves and the screw shaft 34 is driven to rotate, and the driving force is transmitted in this order to the fourth transmission gear 27, the third transmission gear 26, the second transmission gear 25, and the first transmission gear 24. Then, the rotation of the first transmission gear 24 rotates the brake disc 40 provided on the rotation shaft 24a.

[0024] Because the brake disc 40, made of aluminum, rotates while facing the magnet 43 housed in the magnet holder 42, eddy currents are generated in the brake disc 40 due to the action of electromagnetic induction between the brake disc 40 and the magnet 43. The magnetic flux generated by the eddy currents interacts with the magnetic force of the magnet 43, generating a braking force that brakes the rotation of the brake disc 40. The generation of braking force in the brake disc 40 suppresses the rotational speed of the brake disc 40, which in turn suppresses the rotational speed of the screw shaft 34 of the ball screw 33 connected to the brake disc 40 via the transmission gear group 23. The suppression of the rotational speed of the screw shaft 34 suppresses the axial movement speed of the nut 35 and the shortening speed of the rod 31, thereby suppressing the descent speed of the cargo door connected to the rod 31. In other words, the brake disc 40 and the magnet 43 act as an eddy current brake device that brakes the movement of the rod 31 and suppresses the descent speed of the cargo door.

[0025] 4, 18 magnets 43 are arranged at equal angular intervals on a circumference of the same diameter from the center of the magnet holder 42, and the magnets 43 are arranged alternately with one arranged so that the side facing the brake disc 40 shown in FIG. 3 is the north pole and the other arranged so that the side facing the brake disc 40 is the south pole. This makes it possible to increase the number of magnetic fluxes of the magnets 43 that link with the brake disc 40, and to increase the braking force that brakes the brake disc 40.

[0026] Furthermore, the magnet holder 42 holds the magnet 43 by inserting the cylindrical magnet 43 into a cylindrical accommodation hole 42a formed on the circumference of a circle of the same diameter. Therefore, the magnet 43 can be easily arranged in the magnet holder 42, and the braking force acting on the brake disc 40 can be easily adjusted by rearranging the magnet 43 once it has been arranged, taking into account the necessary braking force acting on the brake disc 40.

[0027] As described above, the linear actuator 10 according to the first embodiment includes the motor 20, the drive gear 22 provided on the rotation shaft 21 of the motor 20, the transmission gear group 23 connected to the drive gear 22 and transmitting the rotational driving force of the drive gear 22, the linear motion mechanism unit 30 connected to the transmission gear group 23 and performing linear motion by the rotational driving force transmitted by the transmission gear group 23, and the case 11, case end 11a, mounting portion 11b, and cover 12 that accommodate the motor 20, the drive gear 22, the transmission gear group 23, and the linear motion mechanism unit 30. The transmission gear group 23 has first, second, third, and fourth transmission gears 24, 25, 26, and 27, and performs linear motion. The mechanism unit 30 has a ball screw 33 connected to the transmission gear group 23, a nut 35 threaded onto the ball screw 33, and a rod 31 connected to the nut 35, and is also equipped with a brake disc 40 rotatably connected to the rotation axis of the first transmission gear 24, a magnet holder 42 that shares a central axis with the brake disc 40 and faces the brake disc 40, and is fixed to the cover 12, and multiple magnets 43 arranged circumferentially on the magnet holder 42, so that sudden operation of the linear motion mechanism unit 30 can be suppressed when a failure occurs in the linear actuator 10.

[0028] In addition, the magnets 43 are arranged at equal angular intervals along the circumferential direction of the magnet holder 42, with some magnets oriented with their north poles facing the brake disc 40 and others oriented with their south poles facing the brake disc 40, thereby increasing the number of magnetic fluxes interlinked with the brake disc 40 and increasing the braking force that brakes the brake disc 40.

[0029] Embodiment 2 Next, the configuration of a linear actuator according to a second embodiment of the present invention will be described. In the following embodiments, the same reference symbols as those in Figures 1 to 4 indicate the same or similar components, and detailed descriptions thereof will be omitted. The linear actuator according to the second embodiment is different from the linear actuator of the first embodiment in that the arrangement of the magnets is changed so that two or more consecutive north or south poles of the magnets face the brake disc. Fig. 5 is a diagram showing the arrangement of magnets according to the present embodiment 2. Magnet 43a, magnet 43b adjacent to magnet 43a, and magnet 43c adjacent to magnet 43b are each arranged so that the side facing brake disc 40 shown in Fig. 2 is the north pole.

[0030] That is, three magnets 43a, 43b, and 43c are arranged consecutively along the circumferential direction so that the side facing the brake disc 40 is the north pole. The other magnets 43 are arranged alternately, with some arranged so that the side facing the brake disc 40 is the north pole and others arranged so that the side facing the brake disc 40 is the south pole. The rest of the configuration is the same as in the first embodiment.

[0031] In the first embodiment, as shown in Fig. 4, the magnets 43 are arranged alternately, with some magnets being arranged so that the side facing the brake disc 40 is the north pole and others being arranged so that the side facing the brake disc 40 is the south pole. On the other hand, in the second embodiment, the magnets 43a, 43b, and 43c are arranged in a series of three magnets along the circumferential direction, with the north pole being the side facing the brake disc 40. Therefore, in the second embodiment, compared to the first embodiment, the magnetic flux linking the brake disc 40 is smaller in the portions where the magnets 43a, 43b, and 43c are arranged when the brake disc 40 is rotating. As a result, in the second embodiment, the braking force acting on the brake disc 40 is smaller than in the first embodiment, and therefore the braking force acting on the linear motion mechanism unit 30 is also reduced.

[0032] In this way, in the linear actuator 10 according to the second embodiment, the magnets 43a, 43b, and 43c are arranged at equal angular intervals along the circumferential direction of the magnet holder 42, with two or more consecutive north poles facing the brake disc 40. Therefore, the magnetic flux interlinking with the brake disc 40 is smaller in the areas where the magnets 43a, 43b, and 43c are arranged, and therefore the braking force acting on the brake disc 40 and the linear motion mechanism unit 30 can be set lower than in the first embodiment.

[0033] In addition, the other magnets 43 are arranged at equal angular intervals along the circumferential direction of the magnet holder 42, with some magnets oriented with their north poles facing the brake disc 40 and others oriented with their south poles facing the brake disc 40, so that sufficient braking force acting on the brake disc 40 can be secured in the areas where the other magnets 43 are arranged.

[0034] In the second embodiment, the magnets 43a, 43b, and 43c are arranged so that three consecutive north poles face the brake disc 40 in the circumferential direction, but they may also be arranged so that three consecutive south poles face the brake disc 40 in the circumferential direction. Also, the number of magnets arranged consecutively in the circumferential direction so that the sides facing the brake disc 40 have the same pole may be at least two or more, as long as it is less than the total number of accommodating holes 42a of the magnet holder 42.

[0035] Embodiment 3 Next, we will explain the configuration of a linear actuator according to embodiment 3 of the present invention. The linear actuator according to embodiment 3 differs from the linear actuator of embodiment 1 in that the magnets are arranged in the magnet holder in a sectorial range with a central angle exceeding 180°. 6 is a diagram showing the arrangement of magnet 43 according to embodiment 3. Magnet 43 is not inserted into accommodation hole 42b, which is one of the accommodation holes of magnet holder 42. That is, magnet 43 in embodiment 3 is arranged within the range of sector B, which is centered on central axis A of magnet holder 42 and has central angle C exceeding 180°. The other configurations are the same as those in embodiment 1.

[0036] In comparison with the first and second embodiments of the present invention, in the third embodiment, the magnetic flux interlinking with the brake disc 40 is smaller in the portion of the accommodating hole 42b where the magnet 43 is not accommodated, and therefore the braking force acting on the brake disc 40 is lower than in the first and second embodiments, thereby reducing the braking force acting on the linear motion mechanism unit 30.

[0037] In this way, in the linear actuator 10 according to the third embodiment, the magnet 43 is arranged in the circumferential direction of the magnet holder 42 within the range of a sector B having a central angle C of more than 180° centered on the central axis A, and therefore the braking force acting on the brake disc 40 and the linear motion mechanism unit 30 can be set lower than in the first and second embodiments.

[0038] In this embodiment 3, the number of accommodating holes 42b of the magnet holder 42 in which the magnet 43 is not provided is one, but the number of accommodating holes 42b of the magnet holder 42 in which the magnet 43 is not provided may be two or more, as long as the magnet 43 is arranged within the range of a sector B centered on the central axis A of the magnet holder 42 and having a central angle C exceeding 180 degrees.

[0039] Embodiment 4 Next, we will explain the configuration of a linear actuator according to embodiment 4 of the present invention. The linear actuator according to embodiment 4 differs from the linear actuator of embodiment 1 in that the magnets are arranged in the magnet holder in a sectorial range with a central angle of 180° or less. 7 is a diagram showing the arrangement of magnets according to the fourth embodiment. Magnets 43 are not inserted into nine consecutive accommodating holes 42b out of a total of 18 accommodating holes in magnet holder 42. That is, magnets 43 in the fourth embodiment are arranged within the range of a sector B whose center is on central axis A of magnet holder 42 and whose central angle C is 180° or less. The rest of the configuration is the same as that of the first embodiment.

[0040] In comparison with Embodiments 1 and 2, in this Embodiment 4, magnets 43 are not accommodated in nine consecutive accommodation holes 42b out of a total of 18 accommodation holes, and therefore the magnetic flux linking with the brake disc 40 is smaller in the area of ​​accommodation holes 42b, and the braking force acting on the brake disc 40 is lower than in Embodiment 1, and therefore the braking force acting on the linear motion mechanism unit 30 is also lower. Also, compared with Embodiment 3, in the magnet holder 42 of the invention of this Embodiment 4, the magnets 43 are arranged within the range of sector B with a central angle C of 180° or less, and therefore the width of the arrangement portion of the magnets 43 that brake the brake disc 40 is half or less, and therefore the braking force acting on the brake disc 40 is lower than in Embodiment 3, and therefore the braking force acting on the linear motion mechanism unit 30 is also lower.

[0041] In this way, in the linear actuator of this embodiment 4, the magnet 43 is arranged on the circumference of the magnet holder 42 within the range of a sector B centered on the central axis A and having a central angle C of 180° or less, so that the braking force acting on the brake disc 40 and the linear motion mechanism unit 30 can be set lower than in embodiments 1, 2 and 3.

[0042] In this embodiment 4, the number of accommodating holes 42b of the magnet holder 42 in which the magnet 43 is not provided is nine, but the number of accommodating holes 42b of the magnet holder 42 in which the magnet 43 is not provided may be any other number as long as the magnet 43 is arranged within the range of a sector B centered on the central axis A of the magnet holder 42 and having a central angle C of 180° or less.

[0043] Embodiment 5 Next, we will explain the configuration of a linear actuator according to embodiment 5 of the present invention. In contrast to the linear actuator of embodiment 1, the linear actuator according to embodiment 5 has magnets arranged in the accommodating holes of the magnet holder at every other magnet in the circumferential direction. 8 is a diagram showing the arrangement of magnets according to the fifth embodiment. Magnets 43, 43a are provided in accommodating holes 42a of magnet holder 42, spaced apart by the width of one accommodating hole 42b. That is, magnets 43, 43a are not accommodated in accommodating holes 42b adjacent to accommodating holes 42a that accommodate magnets 43, 43a, and magnets 43, 43a are accommodated in accommodating holes 42a adjacent to accommodating holes 42b that do not accommodate magnets 43, 43a.

[0044] In addition, in the fifth embodiment, the first to eighth magnets 43 are arranged so that the side facing the brake disc 40 is the north pole and the second magnets 43 are arranged so that the side facing the brake disc 40 is the south pole, and the ninth magnet 43a is arranged so that the side facing the brake disc 40 is the north pole. In other words, the ninth magnet 43a is arranged so that it is adjacent to the magnet 43 whose side facing the brake disc 40 is the south pole and the magnet 43 whose side facing the brake disc 40 is the north pole. The other configurations are the same as those in the first embodiment.

[0045] In comparison with Embodiment 1, in Embodiment 5, magnets 43, 43a are provided in nine of the 18 accommodating holes 42a, spaced apart by the width of one accommodating hole 42b. Therefore, the magnetic flux linking with the brake disc 40 is smaller around the entire circumferential direction of the magnet holder 42, so that the braking force acting on the brake disc 40 is lower than in Embodiment 1, and therefore the braking force acting on the linear motion mechanism 30 is also lower. Furthermore, compared with Embodiments 2, 3, and 4, in the magnet holder 42 of the present invention in Embodiment 5, the magnets 43, 43a are provided at intervals of one accommodating hole 42b, so that the magnetic flux linking with the brake disc 40 is smaller, so that the braking force acting on the brake disc 40 is lower than in Embodiments 2, 3, and 4, and therefore the braking force acting on the linear motion mechanism 30 is also lower.

[0046] In this way, in the linear actuator 10 according to the fifth embodiment, the magnet holder 42 has a plurality of accommodating holes 42a, 42b formed at equal angular intervals along the circumferential direction, the magnet 43 is accommodated in the accommodating hole 42a, and between adjacent magnets 43 there are accommodating holes 42b that do not accommodate a magnet 43. Therefore, the braking force acting on the brake disc 40 can be set lower than in the first, second, third and fourth embodiments, and the braking force acting on the linear motion mechanism unit 30 can be set lower.

[0047] In this embodiment 5, the ninth magnet 43a is positioned so that the side facing the brake disc 40 is the north pole, but it may also be positioned so that the side facing the brake disc 40 is the south pole.

[0048] Embodiment 6 Next, a description will be given of the configuration of a linear actuator according to embodiment 6 of the present invention. The linear actuator according to embodiment 6 is different from the linear actuator according to embodiment 5 in that the polarity direction of the magnet is changed. 9 is a diagram showing the arrangement of magnets according to the sixth embodiment. Magnets 43 are provided in the accommodation holes 42a of the magnet holder 42, spaced apart by one accommodation hole 42b. Three magnets 43, each with a north pole on the side facing the brake disc 40, are arranged consecutively along the circumferential direction, followed by two magnets 43, each with a south pole on the side facing the brake disc 40, followed by two magnets 43, each with a north pole on the side facing the brake disc 40, followed by two magnets 43, each with a north pole on the side facing the brake disc 40, and finally two magnets 43, each with a south pole on the side facing the brake disc 40, arranged consecutively along the circumferential direction. The rest of the configuration is the same as in the first embodiment.

[0049] In comparison with the first to fourth embodiments, in the sixth embodiment, magnets 43 are provided spaced apart from one another in nine of the total of eighteen accommodating holes 42a, and the magnetic flux linking with the brake disc 40 is reduced around the entire circumference of the magnet holder 42, resulting in a lower braking force acting on the brake disc 40 than in the first embodiment. Furthermore, in the magnet holder 42 of the invention of the sixth embodiment, the polarities of the magnets 43 are not arranged alternately but are arranged continuously along the circumferential direction, resulting in a smaller magnetic flux linking with the brake disc 40 and a lower braking force acting on the brake disc 40 than in the fifth embodiment. That is, in the sixth embodiment, the braking force acting on the brake disc 40 is set lower than in the first, second, third, fourth, and fifth embodiments, and therefore the braking force acting on the linear motion mechanism 30 can be set lower.

[0050] In this embodiment 6, the number of consecutive poles of the magnet 43 along the circumferential direction on the side facing the brake disc 40 is just an example, and the number of consecutive poles along the circumferential direction may be any other number.

[0051] Furthermore, in the fifth and sixth embodiments of the present invention, the magnets 43 are arranged at intervals of one accommodating hole 42b along the circumferential direction, but this is not limited to this, and the magnets 43 may be arranged at intervals equal to the number of accommodating holes 42b.

[0052] When comparing the braking forces acting on the brake disc 40 in the linear actuator 10 according to the above-described first to sixth embodiments, the braking forces acting on the brake disc 40 in descending order are: first embodiment, second embodiment, third embodiment, fourth embodiment, fifth embodiment, and sixth embodiment. Therefore, the braking forces acting on the linear motion mechanism unit 30 in descending order are: first embodiment, second embodiment, third embodiment, fourth embodiment, fifth embodiment, and sixth embodiment.

[0053] Embodiment 7 Next, a description will be given of the configuration of a linear actuator according to embodiment 7 of the present invention. The linear actuator according to embodiment 7 differs from the linear actuator of embodiment 1 in that magnets are arranged in multiple concentric circles. FIG. 10 is a diagram showing the arrangement of magnets according to the seventh embodiment. Eighteen first magnets 43d are arranged at equal angular intervals on a first circumference of the magnet holder 42c, with the same diameter from the central axis A. Each first magnet 43d is a cylindrical magnet formed to be able to fit into each accommodating hole 42a. One first magnet 43d is arranged so that its side facing the brake disc 40 shown in FIG. 3 has its north pole, and the other first magnet 43d is arranged so that its side facing the brake disc 40 has its south pole, alternately arranged in the circumferential direction. Furthermore, 18 second magnets 43e are arranged at equal angular intervals on a second circumference of the magnet holder 42c, with the same diameter from the central axis A and a smaller diameter than the first circumference. Each second magnet 43e is a cylindrical magnet formed to be able to fit into each accommodating hole 42a. One second magnet 43e is arranged so that its side facing the brake disc 40 shown in FIG. 3 has its north pole, and the other second magnet 43e is arranged so that its side facing the brake disc 40 has its south pole, alternately arranged in the circumferential direction.

[0054] When viewing magnet holder 42c from the direction along central axis A, first magnets 43d and second magnets 43e are arranged so that imaginary line D extending from the center of each first magnet 43d to central axis A of magnet holder 42c overlaps with imaginary line E extending from the center of each second magnet 43e to central axis A of magnet holder 42c. In other words, each first magnet 43d provided on the radially outer side and second magnet 43e provided on the radially inner side are arranged adjacent to each other along the radial direction.

[0055] Furthermore, the first magnet 43d and the second magnet 43e, which are arranged so that the imaginary lines D and E overlap, are arranged so that the polarity facing the brake disc 40 differs from that of the magnets adjacent to them in the radial direction. That is, in FIG. 7, the second magnet 43e adjacent to the inside of the first magnet 43d, which has an N pole on the side facing the brake disc 40, is arranged so that the polarity facing the brake disc 40 is an S pole. Furthermore, the second magnet 43e adjacent to the inside of the first magnet 43d, which has an S pole on the side facing the brake disc 40, is arranged so that the polarity facing the brake disc 40 is an N pole. The other configurations are the same as those in the first embodiment.

[0056] In this way, the magnets include first magnets 43d arranged in the magnet holder 42c at equal angular intervals on a first circumference centered on the central axis A of the brake disc 40, and second magnets 43e arranged in the magnet holder 42c at equal angular intervals on a second circumference centered on the central axis A and having a diameter smaller than the first circumference, so that the braking force acting on the brake disc 40 and the linear motion mechanism unit 30 can be improved without changing the diameter of the magnet holder 42c.

[0057] Furthermore, since the number of first permanent magnets 43d and the number of second permanent magnets 43e are the same, and a virtual line D extending from the center of each first permanent magnet 43d to the central axis A overlaps with a virtual line E extending from the center of each second permanent magnet 43e to the central axis A, the braking force acting on the brake disc 40 and the linear motion mechanism unit 30 can be more effectively improved.

[0058] Embodiment 8 Next, the configuration of a linear actuator according to embodiment 8 of the present invention will be described. In the following embodiments, the same reference numerals as those in FIG. 10 of embodiment 7 indicate the same or similar components, and detailed description thereof will be omitted. The linear actuator according to embodiment 8 is different from the linear actuator of embodiment 7 in that the position of the second magnet is changed. Fig. 11 is a diagram showing the arrangement of magnets according to embodiment 8. Eighteen first magnets 43d are arranged at equal angular intervals on a first circumference of the magnet holder 42d, the first circumference having the same diameter from the central axis A, and eighteen second magnets 43e are arranged at equal angular intervals on a second circumference having a smaller diameter than the first circumference. The first magnets 43d and second mass nets 43e are arranged alternately in the circumferential direction, with some arranged so that the side facing the brake disc 40 shown in Fig. 3 is the north pole and others arranged so that the side facing the brake disc 40 is the south pole.

[0059] When viewing magnet holder 42d from the direction along central axis A, first magnets 43d and second magnets 43e are arranged so that imaginary line D extending from the center of each first magnet 43d to central axis A of magnet holder 42d and imaginary line E extending from the center of each second magnet 43e to central axis A of magnet holder 42d do not overlap but intersect. In other words, second magnets 43e are arranged radially inward of each first magnet 43d so as not to be adjacent to each other. The other configurations are the same as those of embodiment 7.

[0060] In this way, the number of first permanent magnets 43d is the same as the number of second permanent magnets 43e, and a virtual line D extending from the center of each first permanent magnet 43d to the central axis A intersects with a virtual line E extending from the center of each second permanent magnet 43e to the central axis A, so that the braking force acting on the brake disc 40 and the linear motion mechanism unit 30 can be adjusted to be lower than in the case of embodiment 7.

[0061] Embodiment 9 Next, a description will be given of the configuration of a linear actuator according to embodiment 9 of the present invention. The method for manufacturing a linear actuator according to embodiment 9 is to appropriately use magnet holders with different magnet arrangement positions for the linear actuator of embodiment 7. 12 is a diagram showing the arrangement of the first magnet according to embodiment 9. First magnet holder 42e has 18 accommodating holes 42a at equal angular intervals on a first circumference of the same diameter from central axis A. In the arrangement of the first magnets by first magnet holder 42e, first magnets 43d are arranged on the first circumference.

[0062] FIG. 13 is a diagram illustrating the arrangement of second magnets according to the ninth embodiment. The second magnet holder 42f has 18 accommodating holes 42a at equal angular intervals on a second circumference of the same diameter from the central axis A. In the arrangement of the second magnets using the second magnet holder 42f, the second magnets 43e are arranged on the second circumference. This second circumference has a smaller diameter than the first circumference of the first magnet holder 42e shown in FIG. 12. That is, in the arrangement of the second magnets using the second magnet holder 42f shown in FIG. 13, the second magnets 43e are arranged on a second circumference with a smaller diameter than the first circumference of the arrangement of the first magnets using the first magnet holder 42e. Therefore, the braking force acting on the brake disc 40 and the linear motion mechanism 30 is smaller in the arrangement of the second magnets than in the arrangement of the first magnets. The other configurations are the same as those in the seventh embodiment.

[0063] Next, a manufacturing method of the linear actuator according to the ninth embodiment will be described. When manufacturing the linear actuator 10, the first magnet holder 42e and the second magnet holder 42f are formed. Then, when assembling the linear actuator 10, either the first magnet holder 42e with the first magnet arrangement or the second magnet holder 42f with the second magnet arrangement is selected depending on the required braking force acting on the brake disc 40 and the linear motion mechanism 30 of the linear actuator 10. Specifically, the first magnet holder 42e is selected when the required braking force is relatively large, and the second magnet holder 42f is selected when the required braking force is relatively small. Next, a magnet is attached to the selected magnet holder, either the first magnet holder 42e or the second magnet holder 42f, and the selected magnet holder is attached to the mounting portion 11b of the case 11 together with the brake disc 40, magnet base 41, bearing 44, and cover 12 shown in FIG. 2. In this manner, the linear actuator 10 can be manufactured.

[0064] In this way, the method for manufacturing a linear actuator includes the steps of: forming a first magnet holder 42e on a first circumference centered on the central axis A of the brake disc 40, the first magnet holder having a plurality of accommodating holes 42a for accommodating a first magnet 43d; forming a second magnet holder 42f on a second circumference centered on the central axis A and having a diameter smaller than the first circumference, the second magnet holder having a plurality of accommodating holes 42a for accommodating a second magnet 43e; and selecting one magnet holder from the first magnet holder 42e and the second magnet holder 42f, accommodating a magnet in the selected magnet holder, and fixing it to the case portion 12.Therefore, the braking force acting on the brake disc 40 and the linear motion mechanism portion 30 can be appropriately adjusted according to the braking force required for the linear actuator.

[0065] In the ninth embodiment, either the first magnet holder 42e or the second magnet holder 42f is selected and used, but the magnet holder 42c shown in FIG. 10, which was used in the seventh embodiment, may be used, with the magnet provided on either the inner or outer circumferential side. Also, the magnet holder 42d shown in FIG. 11, which was used in the eighth embodiment, may be used, with the magnet provided on either the inner or outer circumferential side. This allows the magnet holder 42c or the magnet holder 42d to be used in common whether the magnet is arranged on the first circumference or the second circumference.

[0066] Furthermore, the position and polarity direction of the magnet in the linear actuator 10 according to embodiments 1 to 9 of the present invention are merely examples, and the position and polarity direction of the magnet 43 may be appropriately changed depending on the magnitude of the desired braking force by considering the braking force acting on the brake disc 40 and linear motion mechanism 30 of the linear actuator 10.

[0067] Furthermore, in the first to ninth embodiments of the present invention, a total of 18 accommodating holes 42a, 42b are provided in the magnet holder, but this number is an example, and the number of accommodating holes 42a, 42b in the magnet holder may be changed appropriately depending on the magnitude of the desired braking force, taking into consideration the braking force acting on the brake disc 40 and the linear motion mechanism 30. Furthermore, the outer shape of the magnet holder may be changed to any shape, such as oval or square, and the shape of the accommodating holes 42a, 42b may be a shape other than circular to match the shape of the magnet 43.

[0068] Furthermore, in the first to ninth embodiments of the present invention, the movable part of the aircraft connected to the rod tip 32 of the linear actuator 10 is the cargo door, but this is not limited thereto, and the rod tip 32 may be connected to any movable part of the aircraft, such as a landing gear or a landing gear cover. Furthermore, in the first to sixth embodiments, the linear actuator 10 is provided in an aircraft, but it may be provided in any other transportation equipment or various facilities, devices, etc.

[0069] Furthermore, in embodiments 1 to 9 of the present invention, the brake disc 40 is attached to the rotating shaft 24a of the first transmission gear 24, but instead, it may be provided on the rotating shaft of any of the second transmission gear 25, the third transmission gear 26, and the fourth transmission gear 27, or on the ball screw 33.

[0070] The components included in the first to ninth embodiments of the present invention and the components included in the modifications thereof can be used in any suitable combination.

[0071] The above describes in detail preferred embodiments, but the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the claims.

[0072] Various aspects of the present disclosure are summarized below as appendices.

[0073] (Appendix 1) A motor (20); a drive gear (22) provided on a rotation shaft (21) of the motor (20); a transmission gear group (23) connected to the drive gear (22) and transmitting the rotational driving force of the drive gear (22); a linear motion mechanism (30) connected to the transmission gear group (23) and linearly moving by the rotational driving force transmitted by the transmission gear group (23); a case portion (11, 11a, 11b, 12) that accommodates the motor (20), the drive gear (22), the transmission gear group (23), and the linear motion mechanism portion (30); Equipped with The transmission gear group (23) has at least one transmission gear (24, 25, 26, 27), The linear motion mechanism (30) includes a ball screw (33) connected to the transmission gear group, a nut (35) threaded onto the ball screw (33), and a rod (31) connected to the nut, a conductor disk (40) rotatably connected to at least one of the rotation shafts of the transmission gears (24, 25, 26, 27) and the ball screw (33); a magnet holder (42) facing the conductive disk (40) and fixed to the case portion (12); A plurality of permanent magnets (43) are arranged in the magnet holder (42); A linear actuator comprising: (Appendix 2) The linear actuator described in Appendix 1, wherein the permanent magnets (43) are arranged alternately at equal angular intervals along the circumferential direction of the conductor disk (40) in the magnet holder (42), with the north pole facing the conductor disk (40) and the south pole facing the conductor disk (40). (Appendix 3) A linear actuator as described in Appendix 1, in which some of the permanent magnets (43) are arranged in the magnet holder (42) along the circumferential direction of the conductor disk (40), with two or more consecutive north poles or south poles facing the conductor disk (40) at equal angular intervals. (Appendix 4) The other permanent magnets (43) are arranged in the magnet holder (42) along the circumferential direction of the conductor disk (40), with the north pole facing the conductor disk (40) and the south pole facing the conductor disk (40) alternately arranged at equal angular intervals. (Appendix 5) A linear actuator according to any one of appendices 1 to 4, wherein the permanent magnet (43) is arranged in the magnet holder (42) along the circumferential direction of the conductor disk (40) within a sector-shaped range having a central angle of more than 180° centered on the central axis of the conductor disk (40). (Appendix 6) A linear actuator according to any one of appendixes 1 to 4, wherein the permanent magnet (43) is arranged in the magnet holder (42) along the circumferential direction of the conductor disk (40) within a sector-shaped range having a central angle of 180° or less, centered on the central axis of the conductor disk (40). (Appendix 7) The magnet holder (42) has a plurality of accommodating holes (42a, 42b) formed at equal angular intervals along the circumferential direction of the conductor disc (40), the permanent magnets (43) are accommodated in the accommodating holes (42a), and between adjacent permanent magnets (43) there is at least one accommodating hole (42b) in which the permanent magnet (43) is not accommodated. A linear actuator as described in any one of Appendices 1 to 6. (Appendix 8) The permanent magnet (43) is In the magnet holder (42), a plurality of first permanent magnets (43d) are arranged at equal angular intervals on a first circumference centered on the central axis of the conductive disk (40); In the magnet holder (42), a plurality of second permanent magnets (43e) are arranged at equal angular intervals on a second circumference having a diameter smaller than that of the first circumference and centered on the central axis; 8. The linear actuator according to any one of claims 1 to 7, comprising: (Appendix 9) A linear actuator as described in Appendix 8, wherein the number of the first permanent magnets (43d) is the same as the number of the second permanent magnets (43e), and a virtual line extending from the center of each of the first permanent magnets (43d) to the central axis overlaps with a virtual line extending from the center of each of the second permanent magnets (43e) to the central axis. (Appendix 10) A linear actuator according to Appendix 8, wherein the number of the first permanent magnets (43d) is the same as the number of the second permanent magnets (43e), and a virtual line extending from the center of each of the first permanent magnets (43d) to the central axis intersects with a virtual line extending from the center of each of the second permanent magnets (43e) to the central axis. (Appendix 11) A method for manufacturing the linear actuator according to any one of Supplementary Notes 1 to 10, forming a first magnet holder (42c) on a first circumference centered on the central axis of the conductive disk (40), the first magnet holder having a plurality of accommodating holes (42a) for accommodating the permanent magnets (43); forming a second magnet holder (42d) on a second circumference having a diameter smaller than that of the first circumference and centered on the central axis, the second magnet holder having a plurality of accommodating holes (42a) for accommodating the permanent magnets (43); a step of selecting one magnet holder (42) from the first magnet holder (42c) and the second magnet holder (42d), accommodating the permanent magnet (43) in the selected magnet holder (42c, 42d), and fixing the magnet holder to the case portion (12); A method for manufacturing a linear actuator having the following features. [Industrial Applicability]

[0074] A linear actuator 10 according to the present invention includes a motor 20, a drive gear 22 provided on a rotation shaft 21 of the motor 20, a transmission gear group 23 connected to the drive gear 22 and transmitting the rotational driving force of the drive gear 22, a linear motion mechanism unit 30 connected to the transmission gear group 23 and moving linearly by the rotational driving force transmitted by the transmission gear group 23, a case 11, a case end 11a, a mounting portion 11b, and a cover 12 for accommodating the motor 20, the drive gear 22, the transmission gear group 23, and the linear motion mechanism unit 30, and the transmission gear group 23 has first, second, third, and fourth transmission gears 24, 25, 26, and 27, and the linear motion mechanism unit 30 is connected to the transmission gear group 23. The linear actuator 10 has a ball screw 33 threaded thereto, a nut 35 threaded onto the ball screw 33, and a rod 31 connected to the nut 35. The linear actuator 10 is equipped with a brake disc 40 rotatably connected to at least one of the rotation shafts of the first, second, third, and fourth transmission gears 24, 25, 26, and 27 and the ball screw 33, a magnet holder 42 facing the brake disc 40 and fixed to the cover 12, and a plurality of magnets 43 arranged in the magnet holder 42. Therefore, when a failure occurs in the linear actuator 10, sudden operation of the linear motion mechanism unit 30 can be suppressed, and the linear actuator 10 is suitable for use in driving moving parts of an aircraft. [Explanation of symbols]

[0075] 11 Case (case part) 11a Case end (case part) 11b Mounting part (case part) 12 Cover (case part) 20 Motor 21 Rotation axis 22 Drive gear 23 Transmission gears 24 Transmission gear 25 Transmission gear 26 Transmission gear 27 Transmission gear 30 Linear motion mechanism section 31 Rod 33 Ball screw 35 Nut 40 Brake disc (conductor disc) 42 Magnet holder 42a Receiving hole 42b Storage Cave 42c Magnet Holder 42d Magnet Holder 42e First magnet holder 42f Second magnet holder 43 Magnet (permanent magnet) 43a Magnet 43b Magnet 43c Magnet 43d 1st Magnet 43e Second Magnet

Claims

1. A motor (20); a drive gear (22) provided on a rotation shaft (21) of the motor (20); a transmission gear group (23) connected to the drive gear (22) and transmitting the rotational driving force of the drive gear (22); a linear motion mechanism (30) connected to the transmission gear group (23) and linearly moving by the rotational driving force transmitted by the transmission gear group (23); a case portion (11, 11a, 11b, 12) that accommodates the motor (20), the drive gear (22), the transmission gear group (23), and the linear motion mechanism portion (30); Equipped with The transmission gear group (23) has at least one transmission gear (24, 25, 26, 27), The linear motion mechanism (30) includes a ball screw (33) connected to the transmission gear group, a nut (35) screwed onto the ball screw (33), and a rod (31) connected to the nut, a conductor disk (40) rotatably connected to at least one of the rotation shafts of the transmission gears (24, 25, 26, 27) and the ball screw (33); a magnet holder (42) facing the conductor disk (40) and fixed to the case portion (12); A plurality of permanent magnets (43) arranged in the magnet holder (42); A linear actuator comprising:

2. 2. The linear actuator according to claim 1, wherein the permanent magnets (43) are arranged in the magnet holder (42) along the circumferential direction of the conductor disk (40), with the north pole facing the conductor disk (40) and the south pole facing the conductor disk (40) alternately arranged at equal angular intervals.

3. 2. The linear actuator according to claim 1, wherein a portion of the permanent magnets (43) are arranged in the magnet holder (42) along the circumferential direction of the conductor disk (40), with two or more consecutive north or south poles facing the conductor disk (40) at equal angular intervals.

4. 4. A linear actuator as described in claim 3, wherein the other permanent magnets (43) are arranged in the magnet holder (42) along the circumferential direction of the conductor disk (40), with the north pole facing the conductor disk (40) and the south pole facing the conductor disk (40) alternately arranged at equal angular intervals.

5. A linear actuator as described in any one of claims 1 to 4, wherein the permanent magnet (43) is arranged in the magnet holder (42) along the circumferential direction of the conductor disk (40) within a sector-shaped range having a central angle of more than 180° centered on the central axis of the conductor disk (40).

6. A linear actuator as described in any one of claims 1 to 4, wherein the permanent magnet (43) is arranged in the magnet holder (42) along the circumferential direction of the conductor disk (40) within a sector-shaped range having a central angle of 180° or less centered on the central axis of the conductor disk (40).

7. The magnet holder (42) has a plurality of accommodating holes (42a, 42b) formed at equal angular intervals along the circumferential direction of the conductor disk (40), the permanent magnets (43) are accommodated in the accommodating holes (42a), and between adjacent permanent magnets (43) there is at least one accommodating hole (42b) in which the permanent magnet (43) is not accommodated. A linear actuator as described in any one of claims 1 to 4.

8. The permanent magnet (43) In the magnet holder (42), a plurality of first permanent magnets (43d) are arranged at equal angular intervals on a first circumference centered on the central axis of the conductor disk (40); In the magnet holder (42), a plurality of second permanent magnets (43e) are arranged at equal angular intervals on a second circumference having a diameter smaller than that of the first circumference and centered on the central axis; The linear actuator according to any one of claims 1 to 4, comprising:

9. 9. The linear actuator of claim 8, wherein the number of the first permanent magnets (43d) is the same as the number of the second permanent magnets (43e), and a virtual line extending from the center of each of the first permanent magnets (43d) to the central axis overlaps with a virtual line extending from the center of each of the second permanent magnets (43e) to the central axis.

10. 9. The linear actuator of claim 8, wherein the number of the first permanent magnets (43d) is equal to the number of the second permanent magnets (43e), and a virtual line extending from the center of each of the first permanent magnets (43d) to the central axis intersects with a virtual line extending from the center of each of the second permanent magnets (43e) to the central axis.

11. A method for manufacturing a linear actuator according to any one of claims 1 to 4, comprising: forming a first magnet holder (42c) on a first circumference centered on the central axis of the conductor disk (40), the first magnet holder having a plurality of accommodation holes (42a) for accommodating the permanent magnets (43); forming a second magnet holder (42d) on a second circumference having a diameter smaller than that of the first circumference and centered on the central axis, the second magnet holder having a plurality of accommodating holes (42a) for accommodating the permanent magnets (43); a step of selecting one magnet holder (42) from the first magnet holder (42c) and the second magnet holder (42d), accommodating the permanent magnet (43) in the selected magnet holder (42), and fixing the magnet holder to the case portion (12); A method for manufacturing a linear actuator having the following features.

Images