Linear motion actuator and electrically driven umbrella

Abstract

A linear motion actuator (1) according to an embodiment comprises: an electric motor (62) that has a motor shaft (62a); a speed reduction mechanism (31) that decelerates and outputs the rotation of the motor shaft (62a); a transmission mechanism (40) that is provided between the electric motor (62) and the speed reduction mechanism (31) and transmits the rotation of the motor shaft (62a); and a feed screw mechanism (2) that has a feed screw (19) connected to the speed reduction mechanism (31). The transmission mechanism (40) comprises a transmission flange (41) to which the electric motor (62) is attached, and a transmission shaft (42) that is rotatably supported by the transmission flange (41) and connected to the motor shaft (62a) and the speed reduction mechanism (31). The electric motor (62) is provided so as to be attachable to and detachable from the transmission mechanism (40).

Description

Linear actuator and electric umbrella

[0006] ,

[0001] The present invention relates to a linear actuator and an electric umbrella. This application claims priority for Japanese Patent Application No. 2024-*159192*, filed in Japan on September 13, 2024, and incorporates its content herein by reference.

[0002] A linear actuator converts rotational motion into linear motion to drive an object. The linear actuator includes, for example, a motor having a motor shaft, a speed reduction mechanism connected to the motor shaft, a ball screw to which the rotation of the motor shaft is transmitted via the speed reduction mechanism, and a movable member that meshes with the ball screw and moves in the axial direction of the ball screw as the ball screw rotates. The speed reduction mechanism and the motor are integrally incorporated. When an object is attached to the movable member, the linear actuator can linearly move the object in the axial direction by rotating the ball screw.

[0003] Japanese Patent Application Laid-Open No. 2017-187050

[0004] However, in the above prior art, since the speed reduction mechanism and the motor are integrally incorporated, it becomes difficult to replace only the motor when a problem occurs in the motor. Therefore, there is a problem of poor maintainability. In addition, when a problem occurs in the motor, there is a problem that it is difficult to maintain the function of the linear actuator, such as operating the linear actuator manually.

[0005] The present invention provides a linear actuator and an electric umbrella that can improve maintainability and maintain the function even when a problem occurs in the motor.

[0006] (1) A linear actuator according to one aspect of the present invention comprises a motor having a motor shaft, a reduction mechanism that reduces and outputs the rotation of the motor shaft, a transmission mechanism provided between the motor and the reduction mechanism for transmitting the rotation of the motor shaft, and a lead screw mechanism having a lead screw connected to the reduction mechanism. The transmission mechanism comprises a flange to which the motor is attached, and a transmission shaft that is rotatably supported by the flange and connected to the motor shaft and the reduction mechanism. The motor is detachably mounted to the transmission mechanism.

[0007] This configuration allows for the removal of only the motor in case of a malfunction, for example. This improves the maintainability of the linear actuator. After removing the motor, the function of the linear actuator can be maintained by manually rotating the transmission shaft.

[0008] (2) In the above configuration, at least the lead screw mechanism may be housed in a housing. The flange may be fixed to the housing, and the reduction mechanism may be supported by the flange.

[0009] (3) In the above configuration, the transmission shaft may have a power input section that can receive power other than the power from the motor transmitted via the motor shaft.

[0010] (4) In the above configuration, the power input unit includes a connecting unit to which a tool is connected, and rotation from the other power source may be input via the tool.

[0011] (5) In the above configuration, the connecting portion may be provided at the end of the transmission shaft located on the motor side. The connecting portion may include a polygonal recess into which the tool can be inserted, or a polygonal protrusion that is rotated by the tool.

[0012] (6) An electric umbrella according to another aspect of the present invention comprises a cylindrical base support, a movable support housed within the base support and movable along the axial direction of the base support so as to extend and retract relative to the base support, umbrella ribs provided on the base support and the movable support, which open and close in accordance with the relative movement of the movable support relative to the base support, and a linear actuator that moves the movable support linearly relative to the base support along the axial direction of the base support. The linear actuator comprises a motor having a motor shaft, a reduction mechanism that reduces and outputs the rotation of the motor shaft, a transmission mechanism provided between the motor and the reduction mechanism for transmitting the rotation of the motor shaft, and a lead screw mechanism having a lead screw connected to the reduction mechanism. The transmission mechanism comprises a flange to which the motor is attached, and a transmission shaft rotatably supported by the flange and connected to the motor shaft and the transmission mechanism. The motor is detachably provided with respect to the transmission mechanism.

[0013] This configuration allows for the removal of only the motor if, for example, a motor malfunction occurs. This improves the maintainability of the electric umbrella. After removing the motor, the electric umbrella can still be opened and closed by manually rotating the transmission shaft.

[0014] According to the linear actuator and electric umbrella of the present invention, maintainability can be improved, and functionality can be maintained even if a malfunction occurs in the motor.

[0015] This is a front view of the electric umbrella in the closed state according to an embodiment of the present invention. This is a front view of the electric umbrella in the open state according to an embodiment of the present invention. This is a schematic configuration diagram of part III in Figure 2. This is a schematic configuration diagram of part IV in Figure 2. This is a cross-sectional view of part V in Figure 3 along the vertical direction. This is a schematic configuration diagram of the linear actuator in an embodiment of the present invention. This is an enlarged view of part VII in Figure 6. This is an explanatory diagram of the maintenance method for the linear actuator in an embodiment of the present invention. This is an explanatory diagram of the maintenance method for the linear actuator in an embodiment of the present invention.

[0016] Next, embodiments of the present invention will be described with reference to the drawings.

[0017] <Electric Umbrella> Figures 1 and 2 are front views of the electric umbrella (parasol) 100. Figure 1 shows the umbrella ribs (main ribs 14, secondary ribs 15) of the electric umbrella 100 in the closed state. Figure 2 shows the umbrella ribs of the electric umbrella 100 in the open state. Figure 3 is a schematic diagram of section III in Figure 2. Figure 4 is a schematic diagram of section IV in Figure 2. In Figures 3 and 4, some parts are shown with dashed lines to show the internal structure.

[0018] As shown in Figures 1 to 4, the electric umbrella 100 is installed on a mounting surface F, such as a road surface or floor surface, in places like commercial facilities or outdoors. In the following description, the vertical direction is defined with the electric umbrella 100 installed on the mounting surface F.

[0019] The electric umbrella 100 comprises a cylindrical base column 10 fixed to the installation surface F, a cylindrical lifting column (an example of a movable column in the claim) 11 fitted to the inner circumference of the base column 10, and a linear actuator 1 for raising and lowering the lifting column 11. The base column 10 and the lifting column 11 have their axial directions aligned in the vertical direction. The upper part of the lifting column 11 protrudes (extends) above the base column 10. The linear actuator 1 moves the lifting column 11 linearly along the vertical direction relative to the base column 10.

[0020] An annular lower turn (lower connecting part) 12 is fixed to the upper end of the base support column 10. An annular upper turn (upper connecting part) 13 is fixed to the upper end of the lifting support column 11. A retractable bellows tube 9 is connected to these lower turn 12 and upper turn 13. The bellows tube 9 covers the protruding portion of the lifting support column 11 that extends above the base support column 10 from the outside. The lifting support column 11 is provided to be movable along the vertical direction so as to extend and retract relative to the base support column 10.

[0021] The base ends of multiple ribs 14 are rotatably connected to the lower ferrule 12. The multiple ribs 14 extend radially outward from the lower ferrule 12. The multiple ribs 14 hold umbrella fabric (not shown). A female hinge 16 is attached to the upper side of the longitudinal center of each rib 14. A male hinge 17, described later, is rotatably connected to the female hinge 16.

[0022] The base ends of multiple support ribs 15 are rotatably connected to the upper runner 13 at positions corresponding to the main ribs 14. The multiple support ribs 15 extend radially outward from the upper runner 13. A male hinge 17, which is connected to a female hinge 16, is attached to the tip of each support rib 15. These main ribs 14 and support ribs 15 constitute a link mechanism 18 for opening and closing the umbrella.

[0023] In the following description, the position where the lifting support 11 protrudes sufficiently upward from the base support 10, and the upper wheel 13 is sufficiently far above the lower wheel 12 (see Figure 1), is defined as the raised position of the upper wheel 13. Conversely, the position where the lifting support 11 hardly protrudes from the base support 10, and the upper wheel 13 is close to the lower wheel 12 (see Figure 2), is defined as the lowered position of the upper wheel 13.

[0024] When the upper ferrule 13 is in the raised position, the link mechanism 18 closes the multiple ribs 14 upward so that they narrow upwards. In other words, the electric umbrella 100 closes. When the upper ferrule 13 is in the lowered position, the link mechanism 18 opens the multiple ribs 14 so that they spread out radially. In other words, the electric umbrella 100 opens. More specifically, the link mechanism 18 closes the ribs 14 upwards by pulling up the longitudinal central part (female hinge 16) of the ribs 14 as the upper ferrule 13 rises. The link mechanism 18 pushes down the female hinge 16 of the ribs 14 as the upper ferrule 13 descends, pushing the ribs 14 outwards radially.

[0025] Figure 5 is a cross-sectional view along the vertical direction of section V in Figure 3. As shown in Figures 1 to 5, the base support column 10 comprises a lower support column 10L whose lower end is fixed to the installation surface F, an upper support column 10U to which the lower turntable 12 is fixed, and an intermediate support column 10I connecting the lower support column 10L and the upper support column 10U. Each of these support columns 10L, 10U, and 10I is formed in a cylindrical shape. The lower support column 10L and the intermediate support column 10I are coaxially connected via flange portions 10f that abut against each other. The intermediate support column 10I and the upper support column 10U are coaxially connected via flange portions 10f that abut against each other.

[0026] Multiple (for example, six in this embodiment) restricting plates 24 are fixed to the inner circumferential surfaces of the intermediate support column 10I and the upper support column 10U, respectively. Specifically, the restricting plates 24 are formed on the inner circumferential surface of the intermediate support column 10I near the lower end of the thick reinforcing block 25. The restricting plates 24 are also formed on the inner circumferential surface of the upper support column 10U near the center in the vertical direction. Each restricting plate 24 is arranged at equal intervals in the circumferential direction. Each restricting plate 24 is made of a rectangular metal plate that extends in the vertical direction. Each restricting plate 24 works in cooperation with the guide rail 23, which will be described later, to restrict the rotation of the lifting support column 11 relative to the base support column 10.

[0027] A partition wall 8 is installed between the lower support column 10L and the intermediate support column 10I of the base support column 10. A bearing 7 is provided in the radial center of the partition wall 8. A lead screw 19 is rotatably supported in the partition wall 8 via the bearing 7. The lead screw 19 constitutes part of the linear actuator 1. The lead screw 19 is installed to penetrate the partition wall 8 vertically via the bearing 7. The portion of the lead screw 19 located above the bearing 7 is inserted into the intermediate support column 10I of the base support column 10 and the lower lifting support column 11L of the lifting support column 11.

[0028] The lead screw 19 is, for example, a trapezoidal screw. A male threaded portion (not shown) is formed on the outer circumferential surface of the portion of the lead screw 19 located above the bearing 7. A nut 22 is engaged with the male threaded portion. The nut 22 has a female threaded portion that engages with the male threaded portion of the lead screw 19. Together with the lead screw 19, the nut 22 constitutes a lead screw mechanism (trapezoidal screw) 2. The lead screw mechanism 2 constitutes part of the linear actuator 1.

[0029] The lifting support column 11 comprises a lower lifting support column 11L whose lower region is housed within the base support column 10 so as to be able to move up and down, and an upper lifting support column 11U to which the upper turntable 13 is fixed at the upper end. Both lifting support columns 11L and 11U are formed in a cylindrical shape. The lower lifting support column 11L and the upper lifting support column 11U are coaxially connected via flange portions 11f that abut against each other.

[0030] Multiple guide rails 23 (for example, three in this embodiment) are attached to the outer circumferential surface of the lower lifting support column 11L. Each guide rail 23 is arranged at equal intervals in the circumferential direction. Each guide rail 23 is formed from a metal plate extending in the vertical direction. A recess 23a is formed on the radially outer side surface of each guide rail 23, opening radially outward.

[0031] Each of the restricting plates 24, fixed to the intermediate support 10I and the upper support 10U, is fitted into the recess 23a so as to be slidable in the vertical direction. This restricts the rotation of the lifting support 11 relative to the base support 10, while allowing the guide rails 23 (lower lifting support 11L) to slide vertically relative to each restricting plate 24 (intermediate support 10I and upper support 10U). The inner surface of the recess 23a in each guide rail 23 and each of the restricting plates 24 are polished to reduce sliding resistance.

[0032] An inner flange portion 11if is integrally molded at the lower end of the lower lifting support column 11L so as to close the lower end of the lower lifting support column 11L. A through hole 11h is formed in the radial center of the inner flange portion 11if, penetrating the inner flange portion 11if in the vertical direction. A nut 22 of the feed screw mechanism 2 is inserted into the through hole 11h. The nut 22 and the inner flange portion 11if are fastened and fixed together, for example, by a bolt (not shown). This integrates the nut 22 and the lower lifting support column 11L (lifting support column 11).

[0033] <Linear Actuator> Figure 6 is a schematic diagram of the linear actuator 1. Figure 7 is an enlarged view of part VII in Figure 6. As shown in Figures 5 to 7, the linear actuator 1 includes a drive unit 30 housed within the lower support column 10L of the base support column 10, in addition to the lead screw mechanism 2. An inner flange portion 10if is provided on the inner circumferential surface 10i of the lower support column 10L at a position corresponding to the drive unit 30. The inner flange portion 10if is formed in an annular shape so as to protrude radially inward from the inner circumferential surface 10i of the lower support column 10L.

[0034] Multiple through holes 10b are formed radially on the inner side of the inner flange portion 10if, arranged in a circumferential direction. A drive unit 30 is fixed to the inner flange portion 10if. The drive unit 30 comprises a reduction mechanism 31 connected to the lower end of the lead screw 19, a transmission mechanism 40 attached to the lower part of the reduction mechanism 31, and a motor unit 32 attached to the lower part of the transmission mechanism 40.

[0035] <Reduction Mechanism> As the reduction mechanism 31, for example, an eccentric oscillating type reduction mechanism is used. Detailed illustrations are omitted, but the eccentric oscillating type reduction mechanism mainly consists of a cylindrical case 31a, a carrier 31b and an oscillating gear (not shown) rotatably supported by the case 31a, and a crankshaft (not shown) rotatably supported by the carrier 31b. Multiple through holes 31d that penetrate the case 31a in the vertical direction are formed on the outer circumference of the case 31a at intervals in the circumferential direction. Each through hole 31d is used when attaching the transmission mechanism 40 to the reduction mechanism 31.

[0036] This type of reduction mechanism 31 inputs rotation from an external source to the crankshaft, then reduces the rotation from the external source and outputs it. The reduction mechanism 31 can use either the carrier 31b or the case 31a as the output member. In this embodiment, the case 31a is inserted into the opening 10a of the inner flange portion 10if, and the case 31a is attached to the transmission mechanism 40. Therefore, the reduction mechanism 31 uses the carrier 31b as the output member. An output attachment 33 is attached to the carrier 31b.

[0037] The output attachment 33 comprises a base plate 34 and an output shaft 35. The base plate 34 is attached to the carrier 31b and is formed in a disc shape. The output shaft 35 is formed to protrude upward from the base plate 34. The base plate 34 and the output shaft 35 are integrally molded. The base plate 34 has a plurality of bolt insertion holes 34a that penetrate the base plate 34 in the thickness direction. The plurality of bolt insertion holes 34a are spaced apart in the circumferential direction. Bolts 36 are inserted from above each bolt insertion hole 34a and these bolts 36 are tightened into the female threaded portion 31c formed in the carrier 31b. This integrates the carrier 31b and the output attachment 33.

[0038] The output shaft 35 is positioned coaxially with the lead screw 19. Therefore, the upper end of the output shaft 35 and the lower end of the lead screw 19 face each other in the vertical direction. The upper part of the output shaft 35 and the lower part of the lead screw 19 are connected via a coupling 37. As a result, the rotation of the output shaft 35 is transmitted to the lead screw 19 via the coupling 37.

[0039] <Transmission Mechanism> The transmission mechanism 40 mainly consists of a transmission flange 41 fixed to the inner flange portion 10if and a transmission shaft 42 rotatably supported by the transmission flange 41. The transmission flange 41 comprises a cylindrical flange body 43 and an outer flange portion 44. The outer flange portion 44 is formed to protrude radially outward from the outer circumference of the upper end of the flange body 43. Therefore, the flange body 43 and the outer flange portion 44 are integrally formed.

[0040] The outer flange portion 44 overlaps the lower surface of the inner circumference of the inner flange portion 10if. The outer flange portion 44 has a plurality of female threaded portions 44a formed thereon, which are arranged coaxially with the through hole 10b of the inner flange portion 10if. Therefore, a bolt 45 can be inserted from above the through hole 10b and tightened into the female threaded portions 44a. This fixes the transmission flange 41 (transmission mechanism 40) to the inner flange portion 10if (lower support column 10L).

[0041] A spigot fitting recess (hereinafter simply referred to as the fitting recess) 46 is formed on the upper surface of the flange body 43. The fitting recess 46 is formed in a circular shape when viewed from above. The inner diameter of the fitting recess 46 is smaller than the inner diameter of the inner flange portion 10if. Multiple female threaded portions 46a are formed on the outer circumference of the fitting recess 46 at intervals in the circumferential direction. The case 31a of the reduction mechanism 31, which is inserted into the opening 10a of the inner flange portion 10if, is fitted into the fitting recess 46 configured in this way. In the fitted state, the female threaded portion 46a and the through hole 31d of the case 31a are located coaxially. Therefore, a bolt 59 can be inserted from above the through hole 31d and the bolt 59 can be tightened into the female threaded portion 46a. In this way, the reduction mechanism 31 is supported by the transmission flange 41.

[0042] A receiving recess (reduction mechanism receiving recess) 47 is formed in most of the radial center of the fitting recess 46, avoiding the female thread portion 46a. The receiving recess 47 is formed in a circular shape when viewed from above, similar to the fitting recess 46. A part of the reduction mechanism 31 fitted into the fitting recess 46 is positioned inside the receiving recess 47.

[0043] On the bottom surface 47a of the receiving recess 47, a shaft insertion hole 48 penetrating in the vertical direction is formed at the center in the radial direction. The shaft insertion hole 48 is formed in a stepped hole shape. The shaft insertion hole 48 has a first insertion hole 48a formed at the upper part of the shaft insertion hole 48, a second insertion hole 48b formed below the first insertion hole 48a, and a third insertion hole 48c formed below the second insertion hole 48b. The inner diameter of the second insertion hole 48b is larger than the inner diameter of the first insertion hole 48a. The second insertion hole 48b is connected to the first insertion hole 48a via a first step portion 48d. The inner diameter of the third insertion hole 48c is larger than the inner diameter of the second insertion hole 48b. The third insertion hole 48c is connected to the second insertion hole 48b via a second step portion 48e.

[0044] The outer ring 49a of the rolling bearing 49 is fitted into the second insertion hole 48b. The upper end portion of the outer ring 49a abuts against the first step portion 48d from below, thereby positioning the rolling bearing 49 with respect to the transmission flange 41. A retaining ring 51 is attached to a portion of the second insertion hole 48b located below the rolling bearing 49. Thereby, using the retaining ring 51, the removal of the rolling bearing 49 from the second insertion hole 48b is restricted. An oil seal 52 is fitted into the third insertion hole 48c.

[0045] On the outer peripheral portion at the lower end of the flange body 43, a plurality of female screw portions 43b are formed at intervals in the circumferential direction so as to open to the lower surface 43a. A fitting projection (hereinafter simply referred to as a fitting projection inlay) 43c protruding downward is formed in a portion of the lower surface 43a of the flange body 43 located at the center in the radial direction with respect to the female screw portions 43b. The female screw portions 43b and the fitting projection 43c are used when attaching the motor portion 32 to the transmission mechanism 40.

[0046] The transmission shaft 42 is inserted into the shaft insertion hole 48. The transmission shaft 42 is rotatably supported by the transmission flange 41 via a rolling bearing 49. A retaining ring 56 is attached to the transmission shaft 42 on the side opposite to the retaining ring 51 of the flange body 43 with the bearing 49 interposed therebetween. The retaining ring 56 and the stepped portion 42c formed on the outer peripheral surface of the transmission shaft 42 restrict the axial movement of the transmission shaft 42 with respect to the flange body 43.

[0047] The upper part of the transmission shaft 42 protrudes upward from the bottom surface 47a of the receiving recess 47. External teeth 42a are formed on the outer peripheral surface of the upper end portion of the transmission shaft 42 that protrudes above the bottom surface 47a. The external teeth 42a are meshed with a part of the speed reduction mechanism 31 disposed inside the receiving recess 47. Thereby, the rotation of the transmission shaft 42 is input to the speed reduction mechanism 31.

[0048] The lower end surface 42b of the transmission shaft 42 is located on the same plane as the lower surface of the fitting convex portion 43c. Therefore, the space between the transmission shaft 42 and the flange body 43 is sealed by an oil seal 52. A shaft insertion recess 53 is formed in the central portion in the radial direction of the lower end surface 42b of the transmission shaft 42. Splines 54 are formed on the inner peripheral surface of the shaft insertion recess 53. The splines 54 are used for connecting the transmission shaft 42 and a connecting shaft 69 described later.

[0049] A tool connecting recess 55 is formed in the bottom surface 53a of the shaft insertion recess 53. A tool (see, for example, the tool 102 in FIG. 9) can be inserted into the tool connecting recess 55. The tool connecting recess 55 is formed such that the tool 102 and the transmission shaft 42 are connected so as not to be relatively rotatable. Specifically, the tool connecting recess 55 is formed in a hexagonal hole shape, for example, when viewed from the vertical direction. The tool connecting recess 55 is formed so as to be exposed downward through the shaft insertion recess 53.

[0050] <Motor section> The motor section 32 comprises a motor flange 61 fixed to the transmission flange 41, an electric motor 62 fixed to the lower part of the motor flange 61, and a connecting attachment 63 attached to the motor shaft 62a of the electric motor 62.

[0051] The motor flange 61 comprises a cylindrical portion 64 and an outer flange portion 65 that extends radially outward from the outer circumference of the upper end of the cylindrical portion 64. The cylindrical portion 64 and the outer flange portion 65 are integrally molded. A spigot fitting recess (hereinafter simply referred to as the fitting recess) 66 is formed on the upper surface of the cylindrical portion 64. The fitting recess 66 is formed in an annular shape when viewed from above or below.

[0052] The fitting projection 43c of the flange body 43 is fitted into the fitting recess 66. In this state, the lower surface 43a of the flange body 43 and the outer flange portion 65 of the motor flange 61 are superimposed. The outer flange portion 65 has a plurality of through holes 65a that penetrate the outer flange portion 65 in the vertical direction. The plurality of through holes 65a are arranged coaxially with the female thread portion 43b of the flange body 43. Therefore, a bolt 67 can be inserted from below the through hole 65a and the bolt 67 can be tightened into the female thread portion 43b of the flange body 43. This fixes the motor flange 61 to the transmission flange 41.

[0053] The electric motor 62 is fixed to the cylindrical portion 64 of the motor flange 61 from below. The motor shaft 62a of the electric motor 62 protrudes into the cylindrical portion 64 from below. Therefore, the connecting attachment 63 attached to the motor shaft 62a is inserted into the cylindrical portion 64.

[0054] The connecting attachment 63 comprises a friction fastener 68 attached to the motor shaft 62a and a connecting shaft 69 fastened to the friction fastener 68. The friction fastener 68 has an inner sleeve 71 and an outer sleeve 72. The friction fastener 68 is a so-called keyless bushing. The friction fastener 68 is fixed to the motor shaft 62a by tightening the sleeves 71 and 72 with a bolt 73, utilizing the principle of a wedge.

[0055] The connecting shaft 69 is formed to protrude upward from the outer sleeve 72 of the friction fastener 68. The connecting shaft 69 is arranged coaxially with the motor shaft 62a. The tip of the connecting shaft 69 is inserted into the shaft insertion recess 53. A spline 69a is formed on the outer circumferential surface of the tip of the connecting shaft 69. The spline 69a and the spline 54 of the shaft insertion recess 53 are spline-fitted to each other. Therefore, the connecting shaft 69 is non-rotatably connected to the transmission shaft 42 and is detachably mounted in the axial direction.

[0056] <Assembly of the Linear Actuator> Next, the assembly of the linear actuator 1 will be explained. The transmission mechanism 40, which constitutes the drive unit 30 of the linear actuator 1, is fixed to the inner flange portion 10if provided on the lower support column 10L. The reduction mechanism 31, which constitutes the drive unit 30, is attached to the transmission mechanism 40 so as to be inserted into the opening 10a of the inner flange portion 10if. The motor portion 32, which constitutes the drive unit 30, is also attached to the transmission mechanism 40. For this reason, the reduction mechanism 31, the transmission mechanism 40, and the motor portion 32 are assembled in advance to integrate the drive unit 30. After this, the reduction mechanism 31 is turned upward, and the drive unit 30 is assembled to the lower support column 10L so as to be inserted into the opening 10a of the inner flange portion 10if.

[0057] <Operation of the Linear Actuator> Next, the operation of the linear actuator 1 will be described. The electric motor 62 is driven to rotate the motor shaft 62a. This allows the rotation of the motor shaft 62a to be input to the reduction mechanism 31 via the connecting attachment 63 and the transmission shaft 42. The reduction mechanism 31 reduces the rotation of the motor shaft 62a and outputs it. The output of the reduction mechanism 31 is transmitted to the lead screw 19 via the output attachment 33 and the coupling 37. This allows the lead screw 19 to rotate.

[0058] The nut 22, which engages with the lead screw 19, is fixed to the lifting support column 11 (lower lifting support column 11L). The lifting support column 11 is provided with a plurality of guide rails 23 on the lifting support column 11 and a plurality of restricting plates 24 on the base support column 10, so as to be non-rotatable and slidable in the vertical direction relative to the base support column 10. Therefore, the nut 22 moves along the axial direction of the lead screw 19 as the lead screw 19 rotates in the forward and reverse directions. Consequently, the lifting support column 11 can be raised and lowered relative to the base support column 10 via the nut 22. In other words, the lifting support column 11 can be extended and retracted relative to the base support column 10.

[0059] Incidentally, there is a possibility that a malfunction may occur in the motor unit 32, preventing the linear actuator 1 from operating normally. The maintenance method in such a case will be described in detail below.

[0060] <Maintenance Method for Linear Motor> Figures 8 and 9 are explanatory diagrams of the maintenance method for the linear actuator 1. As shown in Figures 6 to 9, if a problem occurs in the motor section 32, first remove the bolts 67 that fix the motor section 32 to the transmission mechanism 40. At this time, since the transmission shaft 42 and the connecting shaft 69 are spline-fitted, the motor section 32 can be pulled downwards from the transmission mechanism 40 (see arrow Y1 in Figure 8).

[0061] By removing the motor unit 32 from the transmission mechanism 40, the lower end surface 42b of the transmission shaft 42 is exposed. Furthermore, the tool connection recess 55 is exposed downward through the shaft insertion recess 53 formed on the lower end surface 42b of the transmission shaft 42. This allows a tool 102, for example, attached to an electric screwdriver 101, to be inserted into the tool connection recess 55 via the shaft insertion recess 53 (see Figure 9). The electric screwdriver 101 corresponds to another power source. An example of the tool 102 is a hexagonal screwdriver bit.

[0062] By inserting the tool 102 into the tool connection recess 55 and driving the electric screwdriver 101, the rotation of the tool 102 can be input to the reduction mechanism 31 via the transmission shaft 42. Therefore, the linear actuator 1 can be driven using the electric screwdriver 101. After this, by fixing the normal motor unit 32 back to the transmission mechanism 40, the normal operation of the linear actuator 1 can be restored.

[0063] As described above, the linear actuator 1 of this embodiment comprises a motor unit 32, a reduction mechanism 31, a transmission mechanism 40, and a lead screw mechanism 2. The transmission mechanism 40 comprises a transmission flange 41 to which the reduction mechanism 31 and the motor unit 32 are attached, and a transmission shaft 42 rotatably supported by the transmission flange 41. The motor unit 32 is detachably mounted to the transmission mechanism 40. Therefore, even if a malfunction occurs in the motor unit 32, for example, only the motor unit 32 can be removed. Thus, the maintainability of the linear actuator 1 can be improved. Furthermore, even if the transmission shaft 42 is rotated manually after the motor unit 32 has been removed, the function of the linear actuator 1 can be maintained. Thus, it becomes possible to manually open and close the electric umbrella 100.

[0064] In the drive unit 30 of the linear actuator 1, the transmission flange 41 of the transmission mechanism 40 is fixed to the inner flange portion 10if provided on the lower support column 10L. The reduction mechanism 31 is attached to (supported by) the transmission flange 41. Therefore, the reduction mechanism 31 and the transmission mechanism 40 can be removed from the lower support column 10L as a single unit. Consequently, the positioning of the transmission mechanism 40 (transmission flange 41) and the reduction mechanism 31 can be performed regardless of the manufacturing precision of the lower support column 10L (inner flange portion 10if). This improves the ease of assembly of the linear actuator 1.

[0065] A tool connection recess 55 is formed on the lower end surface 42b of the transmission shaft 42. This makes it possible to easily connect, for example, the tool 102 of an electric screwdriver 101 to the transmission shaft 42 when the motor unit 32 is removed. Thus, it becomes possible to operate the linear actuator 1 using power from an electric screwdriver 101 or the like, independently of the motor unit 32.

[0066] The present invention is not limited to the embodiments described above, but includes various modifications to the embodiments described above, without departing from the spirit of the invention.

[0067] For example, in the above embodiment, an example of an electric umbrella 100 was described in which the main ribs 14 are connected to the lower ferrule 12 and the secondary ribs 15 are connected to the upper ferrule 13. However, it is not limited to this, and for example, the main ribs 14 may be connected to the upper ferrule 13 and the secondary ribs 15 may be connected to the lower ferrule 12. In this case, the umbrella can be closed by pulling the longitudinal central part (female hinge 16) of the main rib 14 upward by raising the upper ferrule 13, thereby narrowing the main rib 14 downward. Conversely, the umbrella can be opened by pushing the female hinge 16 of the main rib 14 downward by lowering the upper ferrule 13, thereby pushing the main rib 14 outwards radially.

[0068] In the above-described embodiment, the case in which the lifting support column 11 is housed in a base support column 10 that extends in the vertical direction so as to be able to move up and down was given as an example. However, it is not limited to this, and for example, each support column 10, 11 does not have to be installed on the installation surface F. In other words, the base support column 10 does not have to be fixed. It is sufficient that the lifting support column 11 is provided in relation to the base support column 10 so as to be able to extend and retract.

[0069] In the above-described embodiment, an example of the motor unit 32 was given in which an electric motor 62 is provided. However, it is not limited to this. For example, the motor unit 32 may be a motor that can transmit rotational force to the reduction mechanism 31 via the transmission mechanism 40. In this case, for example, a hydraulic motor can be used instead of the electric motor 62.

[0070] In the above-described embodiment, the case in which the transmission shaft 42 and the connecting shaft 69 are spline-fitted was used as an example. However, it is not limited to this. For example, the transmission shaft 42 and the connecting shaft 69 may be provided in a manner that prevents relative rotation and allows for detachment in the axial direction. For example, the transmission shaft 42 and the connecting shaft 69 may be connected using a key. In this case, it is not necessary to provide the connecting shaft 69 (fastener 68). For example, the motor shaft 62a may be directly attached to the transmission shaft 42 in a manner that prevents relative rotation and allows for detachment in the axial direction.

[0071] In the above-described embodiment, the case in which a tool connection recess 55 is formed on the lower end surface 42b of the transmission shaft 42 was used as an example. However, the invention is not limited to this. For example, the transmission shaft 42 may have a power input section to which other power sources other than the motor section 32 can be input. The tool connection recess 55 is an example of a power input section. For example, the power input section is preferably a connection section to which one of various tools can be connected. As an example of a connection section, it may be a hexagonal hole shape like the tool connection recess 55. For example, instead of the tool connection recess 55, the connection section may be a convex shape to which a wrench or the like (not shown) can be engaged.

[0072] In the embodiments described above, a trapezoidal screw was used as an example of a lead screw 19 in the lead screw mechanism 2. However, it is not limited to this. For example, the lead screw mechanism 2 and the lead screw 19 may be configured to convert rotational motion into linear motion. For example, the lead screw mechanism 2 may be a ball screw. In this case, for example, the nut 22 that engages with the male thread portion of the lead screw 19 may have a plurality of balls (not shown) that roll on the engagement portion with the lead screw 19.

[0073] In the above-described embodiment, an example of a connecting attachment 63 was described, which includes a fastener 68 attached to the motor shaft 62a and a connecting shaft 69 fastened to the fastener 68. However, it is not limited to this, and for example, the connecting shaft 69 may be integrally molded with the fastener 68.

[0074] In the above-described embodiment, the case in which the reduction mechanism 31 and the motor unit 32 are attached to the transmission flange 41 of the transmission mechanism 40 was given as an example. However, the invention is not limited to this, and for example, the motor unit 32 may be attached to the transmission flange 41 at least. In this case, the reduction mechanism 31 may be fixed to, for example, the inner flange 10if. Even in this configuration, if a malfunction occurs in, for example, the motor unit 32, only the motor unit 32 can be removed. Therefore, the same effects as in the above-described embodiment can be achieved.

[0075] In the above-described embodiment, an example of the outer flange portion 44 of the transmission flange 41 was explained using the case where it overlaps the lower surface of the inner circumference of the inner flange portion 10if. However, it is not limited to this, and for example, the outer flange portion 44 only needs to be fixed to the inner flange portion 10if (base support 10), and can be arranged in various ways. In this case, for example, the outer flange portion 44 may overlap the upper surface of the inner circumference of the inner flange portion 10if.

[0076] In the above-described embodiment, an example was given in which a recess 23a opening radially outward is formed on the radially outer side surface of each guide rail 23. The example was given in which a regulating plate 24 fixed to the intermediate support 10I and the upper support 10U is fitted into the recess 23a so as to be slidable in the vertical direction. However, the embodiment is not limited to this, and for example, the protrusions and recesses of each guide rail 23 and each regulating plate 24 may be reversed. In this case, for example, a recess may be formed in each regulating plate 24, and each guide rail 23 may be fitted into this recess.

[0077] Among the embodiments disclosed herein, those composed of multiple objects may be integrated, and conversely, those composed of a single object may be divided into multiple objects. Whether or not they are integrated, the invention can be constructed in a way that achieves its objective.

[0078] Linear actuators and electric umbrellas improve maintainability and allow the function to be maintained even if a motor malfunction occurs.

[0079] 1... Linear actuator 2... Lead screw mechanism 10... Base support (housing) 10L... Lower support (housing) 11... Lifting support (movable support) 14... Main ribs (umbrella ribs) 15... Secondary ribs (umbrella ribs) 19... Lead screw 31... Reduction mechanism 32... Motor section (motor) 40... Transmission mechanism 41... Transmission flange (flange) 42... Transmission shaft 42b... Lower end surface (end) 55... Tool connection recess (power input section, connection section, recess) 62... Electric motor (motor) 62a... Motor shaft 100... Electric umbrella

Claims

1. A linear actuator comprising: a motor having a motor shaft; a reduction mechanism that reduces the rotation of the motor shaft and outputs the reduced rotation; a transmission mechanism provided between the motor and the reduction mechanism for transmitting the rotation of the motor shaft; and a lead screw mechanism having a lead screw connected to the reduction mechanism, wherein the transmission mechanism comprises: a flange to which the motor is attached; and a transmission shaft rotatably supported by the flange and connected to the motor shaft and the reduction mechanism, and the motor is detachably mounted to the transmission mechanism.

2. The linear actuator according to claim 1, comprising a housing that houses at least the lead screw mechanism, the flange being fixed to the housing, and the reduction mechanism being supported by the flange.

3. The linear actuator according to claim 1 or 2, wherein the transmission shaft has a power input section to which a power other than the power from the motor transmitted via the motor shaft can be input.

4. The linear actuator according to claim 3, wherein the power input section includes a connecting section to which a tool is connected, and rotation from the other power source is input via the tool.

5. The linear actuator according to claim 4, wherein the connecting portion is provided at the end of the transmission shaft located on the motor side, and the connecting portion includes a polygonal recess into which the tool can be inserted, or a polygonal protrusion that is rotated by the tool.

6. An electric umbrella comprising: a cylindrical base support; a movable support housed within the base support and movable along the axial direction of the base support so as to extend and retract relative to the base support; umbrella ribs provided on the base support and the movable support, which open and close in accordance with the relative movement of the movable support relative to the base support; and a linear actuator that moves the movable support linearly relative to the base support along the axial direction of the base support, wherein the linear actuator comprises: a motor having a motor shaft; a reduction mechanism that reduces and outputs the rotation of the motor shaft; a transmission mechanism provided between the motor and the reduction mechanism for transmitting the rotation of the motor shaft; and a lead screw mechanism having a lead screw connected to the reduction mechanism, wherein the transmission mechanism comprises: a flange to which the motor is attached; and a transmission shaft rotatably supported on the flange and connected to the motor shaft and the transmission mechanism, wherein the motor is detachably provided with respect to the transmission mechanism.

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