Work machine and blade unit
By adopting an outer sleeve design in the operating machinery, the problem of friction and wear between the retaining unit and the first blade is solved, achieving wear resistance of the retaining unit and extending the service life of the operating machinery.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- MAKITA CORP
- Filing Date
- 2023-03-09
- Publication Date
- 2026-06-09
Smart Images
Figure CN116724750B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to operating machinery and blade units. Background Technology
[0002] Patent Document 1 discloses a working machine. The working machine includes a prime mover, a conversion mechanism that rotates with the prime mover, a first blade connected to the conversion mechanism, a second blade overlapping the first blade in the vertical direction, and a holding unit that holds the first and second blades in an overlapping state. When the conversion mechanism operates, the first blade reciprocates relative to the second blade in a reciprocating direction orthogonal to the vertical direction. The first blade has a first elongated hole in the length direction in the reciprocating direction. The second blade has a second elongated hole in the length direction in the reciprocating direction. The holding unit is inserted into the first elongated hole of the first blade and the second elongated hole of the second blade.
[0003] Existing technical documents
[0004] Patent documents
[0005] Patent Document 1: Japanese Patent Application Publication No. 2016-49082 Summary of the Invention
[0006] The problem the invention aims to solve
[0007] In the aforementioned working machinery, the first blade reciprocates relative to the second blade, causing the retaining unit to rub against the first blade and wear. This specification discloses a technique capable of suppressing wear on the retaining unit.
[0008] Solution for solving the problem
[0009] The working machine disclosed in this specification includes: a prime mover; a conversion mechanism that operates with the rotation of the prime mover; a first blade connected to the conversion mechanism; a second blade overlapping the first blade in the vertical direction; and a holding unit that holds the first and second blades in a vertically overlapping state. When the conversion mechanism operates, the first blade reciprocates relative to the second blade in a reciprocating direction orthogonal to the vertical direction. The first blade has a first elongated hole in the length direction in the reciprocating direction. The second blade has a second elongated hole in the length direction in the reciprocating direction. The holding unit includes: a holding portion inserted into the first elongated hole of the first blade and the second elongated hole of the second blade; and an outer sleeve having a cylindrical shape, supported on the holding portion in a manner that allows rotation about the holding portion.
[0010] According to the above structure, if the first blade reciprocates relative to the second blade, the outer sleeve rotates around the retaining part in coordination with the reciprocating motion of the first blade. This can suppress wear caused by friction between the outer sleeve and the first blade.
[0011] The blade unit disclosed in this specification is a blade unit whose motion of a prime mover is transmitted via a conversion mechanism. The blade unit includes: a first blade connected to the conversion mechanism; a second blade overlapping the first blade in the vertical direction; and a holding unit that holds the first and second blades in a vertically overlapping state. When the conversion mechanism operates with the movement of the prime mover, the first blade reciprocates relative to the second blade in a reciprocating direction orthogonal to the vertical direction. The first blade has a first elongated hole in the length direction in the reciprocating direction. The second blade has a second elongated hole in the length direction in the reciprocating direction. The holding unit includes: a holding portion inserted into the first elongated hole of the first blade and the second elongated hole of the second blade; and an outer sleeve having a cylindrical shape, supported on the holding portion in a manner rotatable about the holding portion.
[0012] Based on the above structure, it can achieve the same effect as the aforementioned operating machinery. Attached Figure Description
[0013] Figure 1 This is a perspective view of the operating machinery 2 in the first embodiment.
[0014] Figure 2 This is a perspective view of the vicinity of the rear end unit 6 of the operating machine 2 in the first embodiment.
[0015] Figure 3 This is a perspective view of the electric motor 32 and the reduction mechanism 34 of the working machine 2 in the first embodiment.
[0016] Figure 4 This is a perspective view of the vicinity of the front end unit 8 of the working machine 2 in the first embodiment.
[0017] Figure 5 This is a longitudinal sectional view near the front end unit 8 of the working machine 2 in the first embodiment.
[0018] Figure 6 This is an exploded perspective view of the blade unit 46 of the working machine 2 in the first embodiment.
[0019] Figure 7 This is an exploded perspective view of the holding unit 80 of the working machine 2 in the first embodiment.
[0020] Figure 8 This is a longitudinal sectional view of the blade unit 46 of the working machine 2 in the first embodiment.
[0021] Figure 9 This is a top sectional view near the front end unit 8 of the working machine 2 in the first embodiment.
[0022] Figure 10 This is an exploded perspective view of the blade unit 246 of the working machine 2 in the second embodiment.
[0023] Explanation of reference numerals in the attached figures
[0024] 2. Working machinery; 8. Front-end unit; 32. Electric motor; 44. Conversion mechanism; 46, 246. Blade unit; 70, 270. First blade; 72, 272. Second blade; 74. Intermediate plate; 76, 276. First guide member; 78, 278. Second guide member; 80. Holding unit; 88, 288. First elongated hole; 90. First central elongated hole; 92. First side elongated hole; 92a. First right elongated hole; 92b. First left elongated hole; 102, 302. Second elongated hole; 104. Second central elongated hole; 106. Second side elongated hole; 106a. Second right elongated hole; 106 b. Second left-end elongated hole; 120. First retaining unit; 122. Second retaining unit; 124. Third retaining unit; 126. Outer sleeve; 128. Inner sleeve; 130. Bolt component; 132. Nut component; 134. Washer component; 136. Retaining part; 138. Shaft part; 140. Head; 288a. First front-end elongated hole; 288b. First rear-end elongated hole; 288c. First central elongated hole; 288d. First central elongated hole; 302a. Second front-end elongated hole; 302b. Second rear-end elongated hole; 302c. Second central elongated hole; 302d. Second central elongated hole; BP. Battery pack. Detailed Implementation
[0025] The present invention will now be described in detail with reference to the accompanying drawings, providing representative and non-limiting examples. This detailed description is merely intended to show those skilled in the art the details of preferred embodiments for carrying out the invention, and is not intended to limit the scope of the invention. Furthermore, in order to provide further improved working machinery and blade units, methods of manufacturing them, and methods of use, the additional features and technical solutions disclosed below may be used independently of other features and technical solutions, or in combination with other features and technical solutions.
[0026] Furthermore, the features and combinations of processes disclosed in the following detailed description are not, in the broadest sense, necessary for carrying out the invention, but are described only to illustrate representative specific examples of the invention. Moreover, in providing additional and useful embodiments of the invention, the various features of the above and following representative examples, as well as the various features recited in the independent and dependent claims, are not necessarily required to be combined in the same order as the examples described herein or in the listed order.
[0027] All features set forth in this specification and / or claims are intended to be disclosed separately and independently of the specific matters disclosed and claimed in the original application, with respect to the structure of the features set forth in the embodiments and / or claims. Furthermore, all numerical ranges and descriptions relating to organizations or groups are intended to limit the specific matters disclosed and claimed in the original application, with the intention of disclosing these intermediate structures.
[0028] In one or more embodiments, the outer sleeve may be disposed in the first elongated hole and the second elongated hole.
[0029] According to the above structure, even if the first blade reciprocates relative to the second blade, only the outer sleeve contacts the first and second blades, while the retaining part does not contact the first and second blades. This suppresses wear on the retaining unit.
[0030] In one or more embodiments, the retaining part may have an inner sleeve that is inserted into an outer sleeve and has a circular cross-sectional shape on its outer circumferential surface. Alternatively, the vertical length of the outer sleeve may be shorter than the vertical length of the inner sleeve.
[0031] In typical machinery, the first and second blades are sometimes sandwiched between the first and second components. If the outer sleeve is longer vertically than the inner sleeve, it may be unable to rotate around the inner sleeve because it is sandwiched between the first and second components. The structure described above prevents the outer sleeve from rotating around the inner sleeve.
[0032] In one or more embodiments, the retaining part may further include: a bolt member having a head that supports the inner sleeve; a nut member threadedly engaged with the bolt member; and a washer member for insertion of the bolt member, disposed between the inner sleeve and the head. Alternatively, the inner sleeve, bolt member, nut member, and washer member may hold the first and second blades in a state where the first and second blades overlap in the vertical direction.
[0033] Based on the above structure, the first blade and the second blade can be held in a state where the first blade and the second blade overlap in the vertical direction using the simple structure of the holding part.
[0034] In one or more embodiments, the inner sleeve may be independent of the bolt member.
[0035] If the inner sleeve and bolt components are a single, integrated structure, the construction of this integrated component becomes complex. Based on the structure described above, it is possible to prevent the construction of the inner sleeve and bolt components from becoming complex.
[0036] In one or more embodiments, the hardness of the outer sleeve may be different from that of the inner sleeve.
[0037] If the outer sleeve rotates around the inner sleeve, frictional heat is generated. If the hardness of the outer sleeve is the same as that of the inner sleeve, frictional heat may sometimes cause the outer sleeve and the inner sleeve to stick together. According to the above structure, it is possible to suppress the sticking of the outer sleeve and the inner sleeve.
[0038] In one or more embodiments, the material of the outer sleeve may be different from that of the inner sleeve.
[0039] If the outer sleeve rotates relative to the inner sleeve, frictional heat is generated. If the outer sleeve and the inner sleeve are made of the same material, frictional heat can sometimes cause the outer sleeve and the inner sleeve to stick together. The structure described above can suppress this sticking.
[0040] In one or more embodiments, the first blade may have a plurality of first elongated holes arranged in the reciprocating direction. Alternatively, the second blade may have a plurality of second elongated holes arranged in the reciprocating direction. Alternatively, the plurality of first elongated holes may include an end-side first elongated hole disposed at one end in the reciprocating direction. Alternatively, the plurality of second elongated holes may include an end-side second elongated hole disposed at one end in the reciprocating direction and overlapping the end-side first elongated hole in the vertical direction. Alternatively, the retaining portion may be inserted into both the end-side first elongated hole and the end-side second elongated hole.
[0041] Generally, when the first blade reciprocates, it vibrates in a predetermined direction. This vibration increases towards the end of the first blade in the left-right direction. If the retaining part is inserted into a first elongated hole and a second elongated hole located at the end in the reciprocating direction, the retaining unit is pressed against the first blade with a greater force due to the reciprocating motion of the first blade. According to this structure, even when the retaining unit is pressed against the first blade, the force exerted on the retaining unit by the outer sleeve rotating around the retaining part can be released. This suppresses wear on the retaining unit.
[0042] In one or more embodiments, the working machine may include multiple retaining units. Alternatively, the multiple first elongated holes may also include a first elongated hole on the other end side disposed at the other end in the reciprocating direction. Alternatively, the multiple second elongated holes may also include a second elongated hole on the other end side disposed at the other end in the reciprocating direction and overlapping the first elongated hole on the other end side in the vertical direction. Alternatively, the retaining portion of one of the multiple retaining units may be inserted into one end side first elongated hole and one end side second elongated hole. Alternatively, the retaining portion of another of the multiple retaining units may be inserted into one end side first elongated hole and one end side second elongated hole.
[0043] The vibration of the first blade caused by its reciprocating motion sometimes increases towards one end in the reciprocating direction and also towards the other end in the reciprocating direction. According to the above structure, even if another retaining unit among the multiple retaining units is pressed against the first blade due to the vibration of the first blade, the force exerted on the other retaining unit by the outer sleeve rotating around the retaining part can be released. This suppresses wear on the other retaining unit among the multiple retaining units.
[0044] (First Embodiment)
[0045] like Figure 1 As shown, the gardening machine 2 of the first embodiment is an electric gardening machine, such as a ground trimmer, used to trim grass, lawn, etc. growing on the ground. The gardening machine 2 includes a linearly extending operating lever 4, a rear end unit 6 mounted at one end of the operating lever 4 along its length, a front end unit 8 mounted at the other end of the operating lever 4 along its length, a pair of wheels 10 mounted near the other end of the operating lever 4 along its length, a ring handle 12 mounted near the center of the operating lever 4 along its length, and a battery pack BP. The gardening machine 2 operates using electricity supplied from the battery pack BP. When the user holds the rear end unit 6 with one hand and the ring handle 12 with the other, pushing the gardening machine 2 forward causes the pair of wheels 10 to rotate, thereby enabling the gardening machine 2 to move on the ground while simultaneously cutting grass, lawn, etc. growing on the ground. Hereinafter, the direction in which the gardening machine 2 moves due to the rotation of the pair of wheels 10 will be referred to as the forward-backward direction, the direction perpendicular to the ground will be referred to as the up-down direction, and the direction perpendicular to both the forward-backward and up-down directions will be referred to as the left-right direction. Furthermore, the direction in which the working machine 2 moves to cut grass, lawn, etc. growing on the ground (in this embodiment, the direction in which the working machine 2 is pushed out) is called the forward direction, and the direction opposite to the forward direction is called the backward direction.
[0046] like Figure 2As shown, the rear unit 6 includes a rear housing 16. The rear housing 16 includes a support portion 18, a grip portion 20, and a battery mounting portion 22.
[0047] The operating lever 4 is inserted into the support portion 18. A main power switch 24 is disposed on the upper surface of the support portion 18. The main power switch 24 switches the on and off states of the working machine 2.
[0048] The grip 20 is located on the rear side of the support 18. The trigger 26 is rotatably mounted on the lower front side of the grip 20. The trigger 26 can be pushed in by the fingers of a user holding the grip 20. If the trigger 26 is pushed in while the machine 2 is in the energized state, the electric motor 32 (described later) will activate. Figure 3 To perform an action.
[0049] Furthermore, the fin 28 is rotatably mounted on the upper front side of the grip 20. The fin 28 can be pushed in by the palm of a user holding the grip 20. With the fin 28 pushed in, the user can push the trigger 26 in. On the other hand, with the fin 28 not pushed in, the user cannot push the trigger 26 in.
[0050] The battery mounting section 22 is located at the rear of the grip section 20. The battery pack BP is detachably mounted to the rear end of the battery mounting section 22. The battery pack BP can be mounted to the battery mounting section 22 by sliding it along the rear end of the battery mounting section 22 from top to bottom relative to the battery mounting section 22. Furthermore, the battery pack BP can be detached from the battery mounting section 22 by sliding it along the rear end of the battery mounting section 22 from bottom to top relative to the battery mounting section 22 from the state where the battery pack BP is mounted to the battery mounting section 22. Therefore, the battery pack BP can be detached from the battery mounting section 22 for charging.
[0051] like Figure 3 As shown, an electric motor 32 and a reduction gear 34 are housed inside the battery mounting section 22. The electric motor 32 is an example of a prime mover. The electric motor 32 is, for example, a brushless motor. In a variation, the electric motor 32 may also be a brushed motor. The electric motor 32 utilizes power from the battery pack BP (see reference BP). Figure 2 The supplied electricity enables it to rotate.
[0052] The reduction mechanism 34 includes a first reduction gear 34a and a second reduction gear 34b. Both gears are spur gears. The first reduction gear 34a is connected to the motor shaft 32a of the electric motor 32. The second reduction gear 34b meshes with the first reduction gear 34a. The second reduction gear 34b has more teeth than the first reduction gear 34a. While the first reduction gear 34a rotates with the rotation of the motor shaft 32a of the electric motor 32, the second reduction gear 34b rotates at a lower speed than the first reduction gear 34a.
[0053] A transmission shaft 36 is connected to the second reduction gear 34b. The transmission shaft 36 extends from the rear unit 6 (see reference). Figure 1 ) Pass through operating lever 4 (refer to) Figure 1 The interior extends to the front-end unit 8 (refer to...) Figure 1 The transmission shaft 36 rotates along with the rotation of the second reduction gear 34b.
[0054] like Figure 4 As shown, the front-end unit 8 is mounted on the operating lever 4 at a position forward of the pair of wheels 10. The front-end unit 8 includes a front-end housing 40 and a reduction mechanism 42 (see reference). Figure 5 ), conversion mechanism 44 (refer to) Figure 5 ) and blade unit 46.
[0055] like Figure 5 As shown, the front housing 40 includes a gear housing 50 and a cover member 52. The gear housing 50 is connected to the front end of the operating lever 4 using screws (not shown). The cover member 52 closes the lower opening of the gear housing 50. This forms a gear storage chamber 56 between the gear housing 50 and the cover member 52.
[0056] A reduction mechanism 42 is disposed in a gear housing 56. The reduction mechanism 42 includes a third reduction gear 42a and a fourth reduction gear 42b. Both the third and fourth reduction gears 42a and 42b are bevel gears. The third reduction gear 42a is connected to the front end of the transmission shaft 36. The fourth reduction gear 42b meshes with the third reduction gear 42a. The fourth reduction gear 42b has more teeth than the third reduction gear 42a. While the third reduction gear 42a rotates with the transmission shaft 36, the fourth reduction gear 42b rotates at a lower speed than the third reduction gear 42a. Furthermore, the fourth reduction gear 42b rotates about a rotation axis along the vertical direction.
[0057] The conversion mechanism 44 is a cam-crank type conversion mechanism. The conversion mechanism 44 converts the electric motor 32 (see reference) Figure 3The action of the motor 32 is converted into other actions. Furthermore, the conversion mechanism 44 transmits the action of the electric motor 32 to the blade unit 46. The conversion mechanism 44 includes a crankshaft 60, an upper plate 62, and a lower plate 64. The crankshaft 60 is rotatably supported on the gear housing 50 and the cover member 52 by means of bearings 66 and 68. The crankshaft 60 is connected to the fourth reduction gear 42b. Furthermore, the crankshaft 60 passes through the cover member 52, and its lower end is disposed outside the gear housing 56.
[0058] The upper plate 62 and lower plate 64 are connected to the lower end of the crankshaft 60. Both the upper plate 62 and lower plate 64 are circular in shape. The upper plate 62 and lower plate 64 rotate due to the rotation of the crankshaft 60. Figure 9 As shown, the rotation center of the upper plate 62 is offset from the center of the circular plate shape of the upper plate 62, and the rotation center of the lower plate 64 is offset from the center of the circular plate shape of the lower plate 64. If the upper plate 62 rotates from the rear to the front, then the lower plate 64 rotates from the front to the rear; if the upper plate 62 rotates from the front to the rear, then the lower plate 64 rotates from the rear to the front.
[0059] Reference Figure 6 The blade unit 46 is described below. The blade unit 46 of this embodiment is capable of trimming grass, lawns, etc., that grow on the ground. The blade unit 46 includes a first blade 70, a second blade 72, an intermediate plate 74, a first guide member 76, a second guide member 78, and multiple (five in this embodiment) retaining units 80.
[0060] The first blade 70 includes a first blade body 82, a plurality of first cutting edges 84, and a first crank plate 86. The first blade body 82 extends in a left-right direction. The lower surface (sliding surface) of the first blade body 82 is orthogonal to the vertical direction. The first blade body 82 has a plurality of (five in this embodiment) first elongated holes 88 extending along its length in the left-right direction. The first elongated holes 88 penetrate the first blade body 82 along its thickness direction (vertical direction). The five first elongated holes 88 include a first central elongated hole 90 and four first side elongated holes 92. The first central elongated hole 90 corresponds to the first elongated hole 88 located in the center of the five first elongated holes 88. The width of the first central elongated hole 90 in the front-back direction is shorter than the width of the first side elongated holes 92 in the front-back direction. The width of the first central elongated hole 90 in the left-right direction is approximately the same as the width of the first side elongated holes 92 in the left-right direction. Two first side elongated holes 92 are positioned to the right of the first central elongated hole 90, and the remaining two first side elongated holes 92 are positioned to the left of the first central elongated hole 90. Hereinafter, the first side elongated hole 92 positioned to the rightmost is sometimes referred to as the first right-end elongated hole 92a, and the first side elongated hole 92 positioned to the leftmost is sometimes referred to as the first left-end elongated hole 92b.
[0061] Multiple first cutting edges 84 protrude forward from the front surface of the first blade body 82. The multiple first cutting edges 84 are arranged in a left-right direction. A first crank plate 86 is located near the center of the first blade body 82 in the left-right direction and is positioned at the rear of the first blade body 82. The first crank plate 86 has a first crank opening 94 that extends vertically through the first crank plate 86. (See upper plate 62 for reference...) Figure 5 The first blade 70 is positioned at the first crank opening 94, thereby connecting the first blade 70 to the conversion mechanism 44 (see reference). Figure 5 ).
[0062] The second blade 72 overlaps the lower side of the first blade 70 in the vertical direction. The second blade 72 has a shape consistent with that of the first blade 70. The second blade 72 includes a second blade body 96, a plurality of second cutting edges 98, and a second crank plate 100. The second blade body 96 extends in the left-right direction. The upper surface (sliding surface) of the second blade body 96 is orthogonal to the vertical direction. The upper surface of the second blade body 96 is opposite to the lower surface of the first blade body 82. The second blade body 96 has a plurality (five in this embodiment) of second elongated holes 102 having a longitudinal direction in the left-right direction. The second elongated holes 102 overlap with the first elongated holes 88 in the vertical direction. The second elongated holes 102 penetrate the second blade body 96 in the thickness direction (vertical direction). The five second elongated holes 102 include a second central elongated hole 104 and four second side elongated holes 106. The second central elongated hole 104 corresponds to the centrally located second elongated hole 102 among the five second elongated holes 102. The front-to-back width of the second central elongated hole 104 is approximately the same as the front-to-back width of the first central elongated hole 90, and shorter than the front-to-back width of the second side elongated hole 106. The left-to-right width of the second central elongated hole 104 is approximately the same as the left-to-right width of the first central elongated hole 90 and the left-to-right width of the second side elongated hole 106, respectively. The front-to-back width of the second side elongated hole 106 is approximately the same as the front-to-back width of the first side elongated hole 92. Two of the second side elongated holes 106 are located to the right of the second central elongated hole 104, and the remaining two second side elongated holes 106 are located to the left of the second central elongated hole 104. Hereinafter, the second elongated hole 106 located on the far right is sometimes referred to as the second right-end elongated hole 106a, and the second elongated hole 106 located on the far left is referred to as the second left-end elongated hole 106b.
[0063] Multiple second cutting edges 98 protrude forward from the front surface of the second blade body 96. The multiple second cutting edges 98 are arranged in a left-right direction. A second crank plate 100 is positioned near the center of the second blade body 96 in the left-right direction and is located at the rear of the second blade body 96. The second crank plate 100 has a second crank opening 108 that extends vertically through the second crank plate 100. (See lower plate 64) Figure 5The second blade 72 is positioned at the second crank opening 108, thereby connecting the second blade 72 to the conversion mechanism 44 (see reference). Figure 5 ).
[0064] The intermediate plate 74 overlaps the upper side of the first blade 70 in the vertical direction. The intermediate plate 74 extends in the horizontal direction. Protrusions 110 extending forward are formed at both ends of the intermediate plate 74. The intermediate plate 74 closes a plurality of first elongated holes 88 from the top. The intermediate plate 74 has a plurality of (five in this embodiment) intermediate threaded holes 74a that penetrate the intermediate plate 74 in the thickness direction (vertical direction). The plurality of intermediate threaded holes 74a are arranged in the horizontal direction.
[0065] The first guide member 76 overlaps the upper side of the intermediate plate 74 in the vertical direction. The first guide member 76 extends in the horizontal direction. The first guide member 76 has a plurality of (five in this embodiment) first threaded holes 76a passing through the first guide member 76 in the thickness direction (vertical direction). The plurality of first threaded holes 76a are arranged in the horizontal direction.
[0066] The second guide member 78 overlaps the lower side of the second blade 72 in the vertical direction. The second guide member 78 includes a second guide member body 112 and a cover member 114. The second guide member body 112 extends in the left-right direction. The second guide member body 112 closes a plurality of second elongated holes 102 from the lower side in the vertical direction. The second guide member body 112 has a plurality of second front threaded holes 112a penetrating the second guide member body 112 in the thickness direction (vertical direction). The plurality of second front threaded holes 112a are arranged in the left-right direction. The cover member 114 is disposed near the center of the second guide member body 112 in the left-right direction and is located at the rear side of the second guide member body 112. The cover member 114 has a plurality of second rear threaded holes 114a penetrating the cover member 114 in the thickness direction (vertical direction). The second guide member 78 is fixed to the cover member 52 (see reference 52) by inserting a screw 116 into the second rear threaded holes 114a. Figure 5 ).
[0067] The five holding units 80 include two first holding units 120, two second holding units 122, and one third holding unit 124. For example... Figure 7 As shown, the first retaining unit 120 includes an outer sleeve 126, an inner sleeve 128, a bolt member 130, a nut member 132, and a washer member 134. Hereinafter, the inner sleeve 128, bolt member 130, nut member 132, and washer member 134 are sometimes referred to as the retaining part 136.
[0068] The outer sleeve 126 has a cylindrical shape. The outer sleeve 126 is made of metal or resin material. For example... Figure 8As shown, the outer sleeve 126 is disposed in the first elongated hole 92 and the second elongated hole 106. The diameter of the outer peripheral surface of the outer sleeve 126 is smaller than the width in the front-rear direction of the first elongated hole 92 and the width in the front-rear direction of the second elongated hole 106, respectively. The thickness (width in the vertical direction) of the outer sleeve 126 is greater than or equal to the combined thickness (width in the vertical direction) of the first blade body 82 and the second blade body 96. In a modified example, the thickness of the outer sleeve 126 may also be less than the combined thickness of the first blade body 82 and the second blade body 96.
[0069] like Figure 7 As shown, the inner sleeve 128 has a cylindrical shape. The inner sleeve 128 is made of metal or resin. The material of the inner sleeve 128 is different from that of the outer sleeve 126. The hardness of the inner sleeve 128 is different from that of the outer sleeve 126. That is, the hardness of the inner sleeve 128 can be either less than or greater than that of the outer sleeve 126. Even when the hardness of the inner sleeve 128 is different from that of the outer sleeve 126, the material of the inner sleeve 128 can be the same as that of the outer sleeve 126.
[0070] like Figure 8 As shown, the inner sleeve 128 is disposed in the first elongated hole 92 and the second elongated hole 106. The inner sleeve 128 is inserted into the outer sleeve 126. The outer circumferential surface of the inner sleeve 128 is opposite to the inner circumferential surface of the outer sleeve 126. The diameter of the outer circumferential surface of the inner sleeve 128 is slightly smaller than the diameter of the inner circumferential surface of the outer sleeve 126. Therefore, the outer sleeve 126 can rotate around the inner sleeve 128. The thickness (width in the vertical direction) of the inner sleeve 128 is greater than the combined thickness of the first blade body 82 and the second blade body 96. Therefore, the inner sleeve 128 is sandwiched between the intermediate plate 74 and the second guide member 78. The inner sleeve 128 cannot move relative to the intermediate plate 74 and the second guide member 78. Furthermore, the thickness of the inner sleeve 128 is greater than the thickness of the outer sleeve 126. Therefore, the outer sleeve 126 is not sandwiched between the intermediate plate 74 and the second guide member 78. The outer sleeve 126 is movable relative to the intermediate plate 74 and the second guide member 78.
[0071] like Figure 7 As shown, the bolt member 130 includes a shaft portion 138 and a head 140. The shaft portion 138 extends in a vertical direction. One end of the shaft portion 138 is threaded into the nut member 132. The head 140 is disposed at the other end of the shaft portion 138.
[0072] like Figure 8As shown, the shaft portion 138 passes through the inner sleeve 128, the first elongated hole 92, the second elongated hole 106, the intermediate threaded hole 74a, and the first threaded hole 76a. The shaft portion 138 supports the inner sleeve 128.
[0073] like Figure 7 As shown, the washer component 134 has a circular plate shape with a through hole 134a at its center. Figure 8 As shown, the shaft portion 138 passes through the through hole 134a. The washer member 134 is sandwiched between the inner sleeve 128 and the head 140 and between the second blade 72 and the head 140.
[0074] If the nut member 132 is threaded onto the shaft portion 138, the first blade 70, the second blade 72, the intermediate plate 74, and the first guide member 76 are clamped between the nut member 132 and the washer member 134. Thus, the retaining portion 136 fixes the vertical position of the second blade 72, the intermediate plate 74, and the first guide member 76 relative to the first blade 70. That is, the retaining portion 136 holds the first guide member 76, the intermediate plate 74, the first blade 70, and the second blade 72 in a state where they overlap vertically.
[0075] like Figure 6 As shown, the second retaining unit 122 includes an outer sleeve 126, an inner sleeve 128, a bolt member 130, and a nut member 132. In the second retaining unit 122, the second guide member body 112 functions as a washer member. Furthermore, the shaft portion 138 passes through the inner sleeve 128, the second front threaded hole 112a, the first side elongated hole 92, the second side elongated hole 106, the intermediate threaded hole 74a, and the first threaded hole 76a.
[0076] The third retaining unit 124 includes an inner sleeve 128, a bolt member 130, and a nut member 132. In the third retaining unit 124, the second guide member body 112 functions as a washer member. Only the inner sleeve 128 is disposed in the first central elongated hole 90 and the second central elongated hole 104. Furthermore, the shaft portion 138 passes through the inner sleeve 128, the second front threaded hole 112a, the first central elongated hole 90, the second central elongated hole 104, the intermediate threaded hole 74a, and the first threaded hole 76a.
[0077] The operation of the first blade 70 and the second blade 72 will be explained next. For example... Figure 9 As shown, if electric motor 32 (refer to...) Figure 3When the upper plate 62 rotates while abutting the inner surface of the first crank opening 94, the lower plate 64 rotates while abutting the inner surface of the second crank opening 108. As a result, the first blade 70 and the second blade 72 reciprocate relative to the front end housing 40 in the left-right direction. If the first blade 70 moves to the left, the second blade 72 moves to the right; if the first blade 70 moves to the right, the second blade 72 moves to the left.
[0078] During the reciprocating motion of the first blade 70 and the second blade 72, the inner sleeve 128 guides the first blade 70 and the second blade 72 simultaneously, abutting against the inner surfaces of the first central elongated hole 90 and the second central elongated hole 104. The inner sleeve 128 is clamped within the intermediate plate 74 (see reference). Figure 6 ) and the second guide member 78 (refer to) Figure 6 Therefore, it does not rotate around the axis 138.
[0079] Furthermore, during the reciprocating motion of the first blade 70 and the second blade 72, the outer sleeve 126 guides the first blade 70 and the second blade 72 simultaneously, abutting against the inner surfaces of the first side elongated hole 92 and the second side elongated hole 106. The outer sleeve 126 is not clamped within the intermediate plate 74 (see reference). Figure 6 ) and the second guide member 78 (refer to) Figure 6 The inner sleeve 128 rotates in conjunction with the reciprocating motion of the first blade 70 and the second blade 72. The inner sleeve 128 is clamped between the intermediate plate 74 (see reference 72). Figure 6 ) and the second guide member 78 (refer to) Figure 6 Therefore, even if the outer sleeve 126 rotates, the inner sleeve 128 will not rotate.
[0080] When the first blade 70 and the second blade 72 reciprocate, they generate back-and-forth vibrations. The further away from the crankshaft 60, that is, the further from the center of the first blade 70 and the second blade 72 towards both ends in the left-right direction, the greater the back-and-forth vibration. Therefore, the back-and-forth vibration of the first blade 70 and the second blade 72 near the first side elongated hole 92 and the second side elongated hole 106 is greater than the back-and-forth vibration of the first blade 70 and the second blade 72 near the first central elongated hole 90 and the second central elongated hole 104. Furthermore, the back-and-forth vibration of the first blade 70 and the second blade 72 is greatest near the first right elongated hole 92a, the first left elongated hole 92b, the second right elongated hole 106a, and the second left elongated hole 106b. Near the first right-end elongated hole 92a, the first left-end elongated hole 92b, the second right-end elongated hole 106a, and the second left-end elongated hole 106b, the first blade 70 and the second blade 72 are pressed against the outer sleeve 126 with a large force as the first blade 70 and the second blade 72 vibrate in the front-back direction. Even though the first blade 70 and the second blade 72 are pressed against the outer sleeve 126 with a large force, the outer sleeve 126 is not easily worn because it rotates around the inner sleeve 128.
[0081] (Effect)
[0082] The working machine 2 includes an electric motor 32 (an example of a prime mover), a conversion mechanism 44 that operates with the rotation of the electric motor 32, a first blade 70 connected to the conversion mechanism 44, a second blade 72 that overlaps the first blade 70 in the vertical direction, and a holding unit 80 that holds the first blade 70 and the second blade 72 in a state where the first blade 70 and the second blade 72 overlap in the vertical direction. When the conversion mechanism 44 operates, the first blade 70 reciprocates relative to the second blade 72 in a left-right direction (an example of a reciprocating direction) orthogonal to the vertical direction. The first blade 70 has a first elongated hole 88 in the horizontal direction with a length direction. The second blade 72 has a second elongated hole 102 in the horizontal direction with a length direction. The retaining unit 80 includes: a retaining portion 136 that is inserted into a first elongated hole 88 of the first blade 70 and a second elongated hole 102 of the second blade 72; and an outer sleeve 126 that has a cylindrical shape and is supported on the retaining portion 136 in a manner that allows it to rotate about the retaining portion 136.
[0083] According to the above structure, if the first blade 70 reciprocates relative to the second blade 72, the outer sleeve 126 rotates around the retaining portion 136 in coordination with the reciprocating motion of the first blade 70. This can suppress wear caused by friction between the outer sleeve 126 and the first blade 70.
[0084] Furthermore, the blade unit 46 is a blade unit whose motion is transmitted to the electric motor 32 (an example of a prime mover) via the conversion mechanism 44. The blade unit 46 includes a first blade 70 connected to the conversion mechanism 44, a second blade 72 overlapping the first blade 70 in the vertical direction, and a holding unit 80 that holds the first blade 70 and the second blade 72 in a vertically overlapping state. When the conversion mechanism 44 operates in conjunction with the electric motor 32, the first blade 70 reciprocates relative to the second blade 72 in a left-right direction (an example of a reciprocating direction) orthogonal to the vertical direction. The first blade 70 has a first elongated hole 88 in the horizontal direction with a length direction. The second blade 72 has a second elongated hole 102 in the horizontal direction with a length direction. The retaining unit 80 includes: a retaining portion 136 that is inserted into a first elongated hole 88 of the first blade 70 and a second elongated hole 102 of the second blade 72; and an outer sleeve 126 that has a cylindrical shape and is supported on the retaining portion 136 in a manner that allows it to rotate about the retaining portion 136.
[0085] Based on the above structure, it can achieve the same effect as the aforementioned operating machinery.
[0086] In addition, the outer sleeve 126 is disposed in the first elongated hole 88 and the second elongated hole 102.
[0087] According to the above structure, even if the first blade 70 reciprocates relative to the second blade 72, only the outer sleeve 126 contacts the first blade 70 and the second blade 72, while the retaining part 136 does not contact the first blade 70 and the second blade 72. This can suppress wear of the retaining unit 80.
[0088] Furthermore, the retaining part 136 includes an inner sleeve 128, which is inserted into the outer sleeve 126 and has a circular cross-sectional shape on its outer circumferential surface. The vertical length of the outer sleeve 126 is shorter than the vertical length of the inner sleeve 128.
[0089] In typical operating machinery, the first blade 70 and the second blade 72 are sometimes sandwiched between the intermediate plate 74 (an example of the first component) and the second guide member 78 (an example of the second component). If the structure has a vertical length of the outer sleeve 126 that is longer than that of the inner sleeve 128, the outer sleeve 126 may be unable to rotate around the inner sleeve 128 because it is sandwiched between the intermediate plate 74 and the second guide member 78. With the structure described above, it is possible to prevent the outer sleeve 126 from rotating around the inner sleeve 128.
[0090] Furthermore, the retaining part 136 also includes: a bolt member 130 having a head 140 supporting the inner sleeve 128; a nut member 132 threadedly engaged with the bolt member 130; and a washer member 134 for the bolt member 130 to be inserted into, disposed between the inner sleeve 128 and the head 140. The inner sleeve 128, bolt member 130, nut member 132, and washer member 134 hold the first blade 70 and the second blade 72 in a vertically overlapping state.
[0091] According to the above structure, the first blade 70 and the second blade 72 can be held in a state where the first blade 70 and the second blade 72 overlap in the vertical direction using the simple structure of the holding part 136.
[0092] Furthermore, the inner sleeve 128 is independent of the bolt member 130.
[0093] If the inner sleeve 128 and the bolt member 130 are a single integrated component, the construction of the single integrated component becomes complex. Based on the above structure, it is possible to prevent the construction of the inner sleeve 128 and the bolt member 130 from becoming complex.
[0094] In addition, the hardness of the outer sleeve 126 is different from that of the inner sleeve 128.
[0095] If the outer sleeve 126 rotates around the inner sleeve 128, frictional heat is generated. If the hardness of the outer sleeve 126 is the same as that of the inner sleeve 128, frictional heat may sometimes cause the outer sleeve 126 and the inner sleeve 128 to stick together. According to the above structure, it is possible to suppress the sticking of the outer sleeve 126 and the inner sleeve 128.
[0096] In addition, the outer sleeve 126 is made of a different material than the inner sleeve 128.
[0097] If the outer sleeve 126 rotates relative to the inner sleeve 128, frictional heat is generated. If the outer sleeve 126 and the inner sleeve 128 are made of the same material, frictional heat may sometimes cause the outer sleeve 126 and the inner sleeve 128 to stick together. According to the above structure, it is possible to suppress the sticking of the outer sleeve 126 and the inner sleeve 128.
[0098] Furthermore, the first blade 70 has a plurality of first elongated holes 88 arranged in a left-right direction. The second blade 72 has a plurality of second elongated holes 102 arranged in a left-right direction. The plurality of first elongated holes 88 includes a first right-end elongated hole 92a (an example of a first elongated hole on one end) located at the right end (an example of one end) in the left-right direction. The plurality of second elongated holes 102 includes a second right-end elongated hole 106a (an example of a second elongated hole on one end) located at the right end (an example of one end) in the left-right direction and overlapping the first right-end elongated hole 92a in the vertical direction. The retaining unit 80 is inserted into the first right-end elongated hole 92a and the second right-end elongated hole 106a.
[0099] Generally, when the first blade 70 reciprocates, it vibrates in a predetermined direction. This vibration increases towards the right end in the left-right direction of the first blade 70. If the retaining part 136 is inserted into the first right-end elongated hole 92a and the second right-end elongated hole 106a located at the left-right end, the retaining unit 80 is pressed against the first blade 70 with a greater force due to the reciprocating motion of the first blade 70. According to the above structure, even when the retaining unit 80 is pressed against the first blade 70, the force on the retaining unit 80 can be released from the first blade 70 by rotating the outer sleeve 126 around the retaining part 136. This can suppress wear on the retaining unit 80.
[0100] Furthermore, the working machine 2 includes multiple holding units 80. The multiple first elongated holes 88 also include a first left-end elongated hole 92b (an example of the first elongated hole on the other end) disposed at the left end (an example of the other end) in the left-right direction. The multiple second elongated holes 102 also include a second left-end elongated hole 106b disposed at the left end (an example of the other end) in the left-right direction and overlapping the first left-end elongated hole 92b in the vertical direction. The holding portion 136 of one of the multiple holding units 80 is inserted into the first right-end elongated hole 92a and the second right-end elongated hole 106a. The holding portion 136 of another of the multiple holding units 80 is inserted into the first left-end elongated hole 92b and the second left-end elongated hole 106b.
[0101] The vibration of the first blade 70 caused by the reciprocating motion of the first blade 70 sometimes increases towards the right end in the left-right direction and also towards the left end in the left-right direction. According to the above structure, even if another retaining unit 80 among the plurality of retaining units 80 is pressed against the first blade 70 due to the vibration of the first blade 70, the force on the other retaining unit 80 from the first blade 70 can be released by rotating the outer sleeve 126 around the retaining portion 136. This can suppress wear on the other retaining unit 80 among the plurality of retaining units 80.
[0102] (Second Embodiment)
[0103] Reference Figure 10 The second embodiment will be described. In the second embodiment, only the differences from the first embodiment will be described, while the same reference numerals will be used for the same points as in the first embodiment, and descriptions will be omitted. The blade unit 246 of the second embodiment is used in a hedge trimmer. The blade unit 246 is fixed to the front housing 40 (see reference 1). Figure 4 ).
[0104] The blade unit 246 includes a first blade 270, a second blade 272, a first guide member 276, a second guide member 278, and a plurality of (four in this embodiment) retaining units 80. The first blade 270 includes a first blade body 282 extending in the front-rear direction, a plurality of first cutting edges 284 disposed on both the left and right surfaces of the first blade body 282, and connected to the upper plate 62 (see reference). Figure 4 The first crank plate 286. The first blade body 282 has a plurality of (four in this embodiment) first elongated holes 288 in the longitudinal direction in the front-rear direction. The first elongated hole 288 disposed at the foremost side will be referred to as the first front end elongated hole 288a, and the first elongated hole 288 disposed at the rearmost side will be referred to as the first rear end elongated hole 288b. Furthermore, the first elongated hole 288 disposed at the rear side of the first front end elongated hole 288a will be referred to as the first central elongated hole 288c, and the first elongated hole 288 disposed at the front side of the first rear end elongated hole 288b will be referred to as the first central elongated hole 288d.
[0105] The second blade 272 overlaps the lower side of the first blade 270 in the vertical direction. The second blade 272 includes a second blade body 296 extending in the front-rear direction, a plurality of second cutting edges 298 disposed on both the left and right surfaces of the second blade body 296, and connected to the lower plate 64 (see reference). Figure 4 The second crank plate 300. The second blade body 296 has a plurality of (four in this embodiment) second elongated holes 302 extending along its length in the front-rear direction. The second elongated holes 302 overlap with the first elongated holes 288 in the vertical direction. Hereinafter, the second elongated hole 302 disposed at the foremost side will be referred to as the second front elongated hole 302a, and the second elongated hole 302 disposed at the rearmost side will be referred to as the second rear elongated hole 302b. Furthermore, the second elongated hole 302 disposed at the rear side of the second front elongated hole 302a will be referred to as the second central elongated hole 302c, and the second elongated hole 302 disposed at the front side of the second rear elongated hole 302b will be referred to as the second central elongated hole 302d.
[0106] The first guide member 276 overlaps the upper side of the first blade 270 in the vertical direction. The second guide member 278 overlaps the lower side of the second blade 272 in the vertical direction.
[0107] The four holding units 80 include two first holding units 120 and two second holding units 122. One first holding unit 120 is inserted into a first front elongated hole 288a and a second front elongated hole 302a, and the other first holding unit 120 is inserted into a first central elongated hole 288c and a second central elongated hole 302c. One second holding unit 122 is inserted into a first rear elongated hole 288b and a second rear elongated hole 302b, and the other second holding unit 122 is inserted into a first central elongated hole 288d and a second central elongated hole 302d.
[0108] In the four retaining units 80, if the nut member 132 is threaded onto the upper part of the shaft portion 138, the retaining portion 136 fixes the vertical positions of the second blade 272, the first guide member 276, and the second guide member 278 relative to the first blade 270. That is, the retaining portion 136 holds the first guide member 276, the first blade 270, the second blade 272, and the second guide member 278 in a vertically overlapping state. The inner sleeve 128 is sandwiched between the first guide member 276 and the second guide member 278, while the outer sleeve 126 is not sandwiched between them. Furthermore, in the second retaining unit 122, the second guide member 278 functions as a washer member.
[0109] The operation of the first blade 270 and the second blade 272 will be explained next. If the electric motor 32 (refer to...) Figure 3 When the blade 270 and the blade 272 rotate relative to the front housing 40 (refer to...), the blade 270 and the blade 272 rotate relative to the front housing 40 (refer to...). Figure 4 It reciprocates along the front-back direction. In this embodiment, the front-back direction is an example of the reciprocating direction. If the first blade 270 moves forward, the second blade 272 moves backward; if the first blade 270 moves backward, the second blade 272 moves forward.
[0110] During the reciprocating motion of the first blade 70 and the second blade 72, the outer sleeve 126 guides the first blade 270 and the second blade 272 while abutting against the inner surfaces of the first elongated hole 88 and the second elongated hole 302. Since the outer sleeve 126 is not sandwiched between the first guide member 276 and the second guide member 278, it rotates around the inner sleeve 128 in conjunction with the reciprocating motion of the first blade 270 and the second blade 272.
[0111] When the first blade 270 and the second blade 272 reciprocate, they vibrate in the left and right directions. The further away from the crankshaft 60 (refer to...) Figure 5The greater the lateral vibration is from the rear end of the first blade 270 and the second blade 272 towards the front end, the stronger the lateral vibration is in the vicinity of the first front end elongated hole 288a and the second front end elongated hole 302a. Near the first front end elongated hole 288a and the second front end elongated hole 302a, the first blade 270 and the second blade 272 are pressed against the outer sleeve 126 with a large force, accompanying the lateral vibration of the first blade 270 and the second blade 272. Even though the first blade 270 and the second blade 272 are pressed against the outer sleeve 126 with a large force, the outer sleeve 126 is not easily worn because it rotates around the inner sleeve 128.
[0112] (Modified Example)
[0113] In one embodiment, the inner sleeve 128 and the bolt member 130 may also be an integral component.
[0114] In one embodiment, the outer sleeve 126 and the inner sleeve 128 can also be configured as ball bearings or needle roller bearings.
[0115] In the above embodiments, the retaining unit 80 includes an outer sleeve 126 and an inner sleeve 128, i.e., two sleeves, but is not limited thereto, and may also include three or more sleeves.
[0116] In one embodiment, the working machine 2 can also be a lawnmower.
[0117] In one embodiment, the working machine 2 may also be without a battery pack BP, and instead use power supplied from an external power source via an external wire to operate.
[0118] In one embodiment, the working machine 2 may also be without a pair of wheels 10.
[0119] In one embodiment, the working machine 2 may also have an engine instead of an electric motor 32.
Claims
1. A type of operating machinery, wherein, The operating machinery includes: prime mover; The conversion mechanism operates as the prime mover rotates; The first blade is connected to the conversion mechanism; The second blade overlaps the first blade in the vertical direction; and A holding unit that holds the first blade and the second blade in a state where the first blade and the second blade overlap in the vertical direction. When the conversion mechanism operates, the first blade reciprocates relative to the second blade along a reciprocating direction orthogonal to the vertical direction. The first blade has a first elongated hole in the longitudinal direction in the reciprocating direction. The second blade has a second elongated hole in the longitudinal direction in the reciprocating direction. The holding unit includes: A retaining part, which is inserted into the first elongated hole of the first blade and the second elongated hole of the second blade; and The outer sleeve, having a cylindrical shape, is supported on the retaining portion in a manner that allows it to rotate about the retaining portion. The retaining part includes an inner sleeve that is inserted into the outer sleeve and has a circular cross-sectional shape on its outer circumferential surface. The vertical length of the outer sleeve is shorter than the vertical length of the inner sleeve.
2. The operating machinery according to claim 1, wherein, The outer sleeve is disposed in the first elongated hole and the second elongated hole.
3. The operating machinery according to claim 1, wherein, The retaining part further includes: A bolt component having a head that supports the inner sleeve; A nut component, threadedly engaged with the bolt component; and A washer component, into which the bolt component is inserted, is disposed between the inner sleeve and the head. The inner sleeve, the bolt member, the nut member, and the washer member hold the first blade and the second blade in a state where the first blade and the second blade overlap in the vertical direction.
4. The operating machinery according to claim 3, wherein, The inner sleeve is independent of the bolt component.
5. The operating machinery according to any one of claims 1 to 4, wherein, The hardness of the outer sleeve is different from that of the inner sleeve.
6. The operating machinery according to any one of claims 1 to 4, wherein, The outer sleeve is made of a different material than the inner sleeve.
7. The operating machinery according to any one of claims 1 to 4, wherein, The first blade has a plurality of first elongated holes arranged along the reciprocating direction. The second blade has a plurality of the second elongated holes arranged along the reciprocating direction. The plurality of the first elongated holes have a first elongated hole disposed on one end side of one end in the reciprocating direction. The plurality of the second elongated holes have a second elongated hole disposed at one end in the reciprocating direction and overlapping with the first elongated hole at one end in the vertical direction. The retaining part is inserted into the first long hole on one end side and the second long hole on one end side.
8. The operating machinery according to claim 7, wherein, The working machine is equipped with multiple of the aforementioned holding units. The plurality of the first elongated holes also include a first elongated hole disposed on the other end side of the other end in the reciprocating direction. The plurality of the second elongated holes also include a second elongated hole on the other end side disposed at the other end in the reciprocating direction and overlapping with the first elongated hole on the other end side in the vertical direction. The retaining portion of one of the plurality of retaining units is inserted into the first elongated hole and the second elongated hole on one end side. The retaining part of another retaining unit among the plurality of retaining units is inserted into the first elongated hole on the other end side and the second elongated hole on the other end side.
9. A blade unit whose motion of a prime mover is transmitted via a conversion mechanism, wherein, The blade unit includes: The first blade is connected to the conversion mechanism; The second blade overlaps the first blade in the vertical direction; and A holding unit that holds the first blade and the second blade in a state where the first blade and the second blade overlap in the vertical direction. When the conversion mechanism operates in response to the action of the prime mover, the first blade reciprocates relative to the second blade along a reciprocating direction orthogonal to the vertical direction. The first blade has a first elongated hole in the longitudinal direction in the reciprocating direction. The second blade has a second elongated hole in the longitudinal direction in the reciprocating direction. The holding unit includes: A retaining part, which is inserted into the first elongated hole of the first blade and the second elongated hole of the second blade; and The outer sleeve, having a cylindrical shape, is supported on the retaining portion in a manner that allows it to rotate about the retaining portion. The retaining part includes an inner sleeve that is inserted into the outer sleeve and has a circular cross-sectional shape on its outer circumferential surface. The vertical length of the outer sleeve is shorter than the vertical length of the inner sleeve.