Power tool
By incorporating a sealing body and a labyrinth seal structure between the controller and switch of a power tool, the problem of insufficient sealing in the electrical connection is solved, achieving high sealing performance and short-circuit prevention, thus improving the reliability of the power tool.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- MAKITA CORP
- Filing Date
- 2022-08-10
- Publication Date
- 2026-07-31
AI Technical Summary
In existing power tools, the electrical connection between the controller and the switch is not well sealed, which can easily lead to the intrusion of substances such as iron powder and cause short circuits.
A sealing body is installed between the opposing surfaces of the controller and the switch. The sealing body seals the area around the two terminals even when they are in direct contact. Combined with a labyrinth sealing structure and a positioning mechanism, this ensures a high degree of sealing for the terminal connection.
Through simple assembly, a high degree of sealing is achieved between the controller and the switch, effectively preventing short circuits and improving the reliability and durability of the electrical connection.
Smart Images
Figure CN115922551B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to power tools such as grinders. Background Technology
[0002] In power tools such as grinders, as disclosed in Patent Document 1, a controller and a switch for turning the motor on / off are housed within a housing, and the controller is electrically connected to the switch. Patent Document 1 discloses an invention for a grinder in which a switch block with a switch is assembled on a housing, a male terminal is formed on the controller, and a connection portion containing a female terminal and having an inlet for the male terminal is formed in the switch block. Simultaneously with assembling the switch block and the controller, the male terminal is inserted into the female terminal and connected to it. In particular, a sealing portion is provided on the male terminal side, which covers the forming surface of the inlet of the connection portion when the male terminal is inserted and connected, thereby providing dust protection to the connection portion. [Existing Technical Documents] [Patent Literature]
[0003] Patent Document 1: Japanese Patent Publication No. 5468459 Summary of the Invention [The technical problem that the invention aims to solve]
[0004] In the aforementioned prior art power tools, since the sealing part is made of resin, it is difficult to ensure high sealing even when the surface covering the inlet of the male terminal is formed, thus raising concerns about allowing iron powder and other substances to enter and cause short circuits.
[0005] Therefore, the object of the present invention is to provide a power tool that can provide high sealing performance for the electrical connection parts of the controller and switch to effectively prevent short circuits. [Technical solutions used to solve technical problems]
[0006] To achieve the above objectives, the power tool of the present invention houses a motor, a controller, and a switch within a housing, wherein the controller has a circuit board and a controller-side terminal electrically connected to the circuit board; the switch has a switch-side terminal electrically connected to the controller-side terminal, the controller-side terminal being disposed on a first opposing surface of the switch side in the controller, and the switch-side terminal being disposed on a second opposing surface of the controller side in the switch, the controller-side terminal and the switch-side terminal being in direct contact and electrically connected, characterized in that a sealing body is provided between the first opposing surface and the second opposing surface, the sealing body sealing the area around the two terminals when the controller-side terminal and the switch-side terminal are in direct contact. [Invention Effects]
[0007] According to the present invention, a simple assembly operation can ensure the sealing between the first phase surface of the controller and the second phase surface of the switch. Therefore, a high degree of sealing can be imparted to the electrical connection between the controller and the switch, thereby effectively preventing short circuits. Attached Figure Description
[0008] Figure 1 This is a side view of the grinder. Figure 2 This is a central longitudinal sectional view of the grinding machine. Figure 3 yes Figure 2 An enlarged view of the rear cover section. Figure 4 This is a 3D view of the rear of the grinder without the rear cover. Figure 5 This is a top view of the rear of the grinder without the rear cover. Figure 6 This is a side view of the rear of the grinder without the rear cover. Figure 7 This is a three-dimensional exploded view of the inner casing, controller, and switch from above. Figure 8 This is a three-dimensional exploded view of the inner casing, controller, and switch from below. Figure 9 is an explanatory diagram of the switch, in which, Figure 9A This represents the main view. Figure 9B This represents a top view. Figure 9C This represents a bottom view. Figure 9D This represents a side view. Figure 9E This represents a sectional view of BB. Figure 10 yes Figure 3 AA sectional view. Figure 11 yes Figure 10 A CC sectional view (where the front motor housing, etc., is omitted). Figure 12 yes Figure 10 DD sectional view. [Explanation of reference numerals in the attached figures] 1: Grinding machine; 2: Gearbox; 3: Motor housing; 4: Rear cover; 5: Spindle; 6: Motor; 8: Switch; 8a: Lower surface; 9: Controller; 9a: Upper surface; 14: Output shaft; 25: Inner housing; 26: Bearing retainer; 27: Brush retainer; 28: Mounting plate; 31: Switch retainer; 32: Controller retainer; 35: Upper retaining wall; 36: Upper mounting base; 37: Upper threaded protrusion; 38: Upper front wall; 39A, 39B: Upper side wall; 42: Front rib; 48: Through hole; 50: Lower 51: Lower mounting base; 52: Lower front wall; 53A, 53B: Lower side wall; 54: Lower threaded protrusion; 60: Housing; 61: Button; 62: Output terminal; 63: Protection plate; 65: Seal; 67: Switch side terminal; 68: Square tube; 75: Positioning plate; 85: Housing; 86: Circuit board; 87: Terminal board; 88: Heat sink; 90: Positioning piece; 94: Power input terminal; 95: Protection tube; 97: Controller side terminal; 98: Front tube; 100: Elastic piece. Detailed Implementation
[0009] In one embodiment of the present invention, a sealing body may be disposed on either the first opposing surface or the second opposing surface, and a resin cylindrical portion may be disposed on the other opposing surface. The cylindrical portion abuts against the sealing body when the controller-side terminal and the switch-side terminal are in direct contact, thereby sealing the area around the two terminals. According to this structure, high sealing performance is achieved by the cylindrical part contacting the sealing surface. In one embodiment of the present invention, a second cylindrical portion made of resin may be provided on one of the opposing surfaces, the second cylindrical portion covering the periphery of the controller-side terminal or the switch-side terminal and protruding towards the cylindrical portion side, wherein, in the state where the controller-side terminal and the switch-side terminal are in direct contact, the cylindrical portion of either the first cylindrical portion or the second cylindrical portion is inserted into the cylindrical portion of the other. According to this structure, the distance between the labyrinth seals at the contact points between the terminals can be increased, thereby improving the sealing performance. In one embodiment of the present invention, the cylindrical portion and the second cylindrical portion may be integrated with the controller or switch. According to this structure, the positions of the first cylindrical section and the second cylindrical section are stable, and it is easy for the first cylindrical section and the second cylindrical section to be inserted into each other. In one embodiment of the invention, the cylindrical portion and the second cylindrical portion may cover the entire periphery of the controller-side terminal or the switch-side terminal. This structure reliably protects both the controller-side terminals and the switch-side terminals.
[0010] In one embodiment of the present invention, the outer casing may have an inner casing between the switch and the controller, with a switch holding portion for holding the switch provided on one side of the inner casing and a controller holding portion for holding the controller provided on the other side. Alternatively, either the cylindrical portion or the second cylindrical portion may be inserted into the other cylindrical portion via a through hole provided in the inner casing. This structure improves the sealing of the electrical connection between the controller and the switch, and also enables the positioning of the cylinder using the through hole. In one embodiment of the present invention, a switch positioning mechanism may be provided, which positions the switch within the inner shell. This structure allows the switch to be positioned stably without wobbling. In one embodiment of the present invention, a controller positioning mechanism may be provided, which positions the controller within the inner shell. This structure allows the controller to be positioned stably without shaking.
[0011] In one embodiment of the invention, the switch may have a housing and an output terminal connected to a motor, and a terminal protection portion is provided on the housing, which covers a portion of the output terminal in a non-contact manner. This structure can prevent short circuits between output terminals. In one embodiment of the present invention, the controller may have a pair of power input terminals that input power to the circuit board, and each power input terminal may have a protective portion for protecting the power input terminal at least on the opposite surface of each other. This structure can prevent short circuits between power input terminals. In one embodiment of the present invention, the sealing body may be a sheet-like elastomer. This structure ensures a larger sealing surface, thus improving sealing performance.
[0012] The embodiments of the present invention will now be described with reference to the accompanying drawings. Figure 1 This is a side view of a grinder, an example of a power tool. Figure 2 This is a central longitudinal section view. Figure 3 yes Figure 2 Enlarged view of the rear. The grinding machine 1 comprises a gearbox 2, a motor housing 3, and a rear cover 4 arranged sequentially from front to back. The gearbox 2 is made of metal, while the motor housing 3 and the rear cover 4 are made of resin. The gearbox 2 causes the main shaft 5 to protrude downwards. The motor housing 3 is cylindrical, extending in the front-to-back direction, and houses the motor 6. A switch 7 is located on the left side of the motor housing 3, allowing it to slide in the front-to-back direction. The rear cover 4 is cylindrical like the motor housing 3 and houses a switch 8 and a controller 9. A power cord 10 is connected to the rear of the rear cover 4. Motor 6 is a commutator motor having a stator 11, a rotor 12, and a commutator 13. An output shaft 14, which is mounted on the rotor 12, extends forward and its top protrudes into the gearbox 2. A bevel gear 15 is provided at the top of the output shaft 14. A fan 16 is provided on the output shaft 14 at the front of the motor housing 3.
[0013] A partition plate 17 is provided between the gearbox 2 and the motor housing 3, and the output shaft 14 passes through the partition plate 17. A bearing 18 supporting the output shaft 14 is provided on the partition plate 17. Inside the gearbox 2, a bevel gear 19 is provided on the upper part of the main shaft 5. The bevel gear 19 meshes with the bevel gear 15 of the output shaft 14. Multiple exhaust ports 20, 20... are formed on the front surface of the gearbox 2. A bearing housing 21 is assembled at the lower part of the gearbox 2. The spindle 5 is supported by a bearing 22 and two bearings 23, 23, wherein the bearing 22 is held in the gearbox 2, and the two bearings 23, 23 are held in the bearing housing 21. A top tool 24, such as a disc-shaped grinding wheel, can be mounted on the lower end of the spindle 5, which protrudes from the bearing housing 21.
[0014] An inner shell 25 is integrally formed at the rear end of the motor housing 3. The inner shell 25 extends rearward within the rear cover 4. Figure 4 , Figure 5 and Figure 6 As shown, the inner housing 25 includes: a bearing retainer 26 on the front side; a pair of brush retainers 27, 27 located above and below the bearing retainer 26; and a mounting plate 28. The bearing retainer 26 is cylindrical with the front-to-back direction as its axis, retaining the bearing 29 and supporting the rear end of the output shaft 14. The brush retainers 27 and 27 are quadrilateral frames with openings at the top and bottom respectively, retaining the brushes 30 and 30 that abut against the commutator 13. The mounting plate 28 extends rearward from the bearing holding portion 26 and the brush holding portions 27, 27. The mounting plate 28 is formed parallel to a plane defined by the front-back and left-right directions. The mounting plate 28 has a switch holding portion 31 for holding the switch 8 on the upper side and a controller holding portion 32 for holding the controller 9 on the lower side. Behind the switch holding portion 31, a wire receiving portion 33 for clamping the power cord 10 is provided on the upper surface of the mounting plate 28.
[0015] The switch holding part 31 includes an upper holding wall 35, an upper mounting base 36, and an upper threaded protrusion 37. like Figure 7 As shown, the upper retaining wall 35 is a quadrilateral wall that is erected on the upper surface of the mounting plate 28 and has an opening on the upper surface. The upper retaining wall 35 has: an upper front wall 38; left and right upper side walls 39A and 39B; and an upper rear wall 40. However, the left upper side wall 39A is only formed on the front side, and a notch 41 is formed on the rear side, thereby opening the left side of the upper retaining wall 35. A front rib 42 is provided in the center of the upper front wall 38 in the left-right direction and in the vertical direction. The front rib 42 is erected so as to cross the upper surface of the bearing retaining part 26 and the rear surface of the upper brush retaining part 27. Vents 43, 43 that pass through the front and rear are formed at the lower part of the connection between the upper front wall 38 and the left and right upper side walls 39A and 39B.
[0016] The front sides of the left and right upper sidewalls 39A and 39B are higher than the upper front wall 38 and the upper rear wall 40. A pair of grooves 44 and 44 are formed along the vertical direction on the opposing inner surfaces of the upper sidewalls 39A and 39B. A locking claw 45 is formed along the front-rear direction on the outer surface of the left upper sidewall 39A. A pair of left and right separating ribs 46 and 46 are formed along the vertical direction on the rear surface of the upper rear wall 40. A pair of holes 47 and 47 are formed on the mounting plate 28 on the left and right outer sides of the separating ribs 46 and 46. Between the upper sidewalls 39A and 39B on the left and right sides, a through hole 48 is formed on the mounting plate 28, which is a horizontally elongated quadrilateral shape when viewed from above. The upper assembly base 36 is formed between the left and right upper sidewalls 39A and 39B and behind the through hole 48, at a height one level lower than the rear upper surface of the mounting plate 28 in the left-right direction. A bottom rib 49 extending in the front-back direction is provided at the center of the upper assembly base 36 in the left-right direction. The upper threaded protrusion 37 is vertically mounted on the mounting plate 28 with its rear side and right side facing upward.
[0017] For example Figure 8 As shown, the controller holding part 32 includes a lower holding wall 50 and a lower mounting base 51. The lower holding wall 50 is a wall that is erected vertically from the left and right sides of the front of the mounting plate 28 and surrounds the lower front surface of the mounting plate 28. The lower retaining wall 50 has a lower front wall 52 and left and right lower side walls 53A and 53B. The lower front wall 52 is integrally formed with the lower brush retaining portion 27. The front portions of the left and right lower side walls 53A and 53B, which are continuous with the lower front wall 52, are longer downward than their rear portions. In the left and right lower side walls 53A and 53B, a pair of downward threaded protrusions 54 are provided rearward on the outer surface of the front portion. A lower mounting base 51 is formed on the entire lower surface of the mounting plate 28, including the area surrounded by the lower retaining wall 50. At the front of the lower mounting base 51, a downwardly projecting protrusion 55 is formed at the center in the left-right direction. The protrusion 55 is located forward of the through hole 48. Between the protrusion 55 and the holes 47, 47, an upwardly recessed recess 56 is formed on the lower surface of the mounting plate 28. The through hole 48 is located within the recess 56.
[0018] The switch 8 is a push-button switch that is activated by pressing a button 61 protruding from the housing 60. The housing 60 has a quadrilateral shape between the left and right upper sidewalls 39A and 39B of the switch holding part 31. The button 61 is positioned rearward on the rear surface of the housing 60. As shown in FIG. 9, a pair of plate-shaped positive and negative output terminals 62, 62 are also provided facing forward on the upper front surface of the housing 60. A pair of protective plates 63, 63 are provided protruding forward on the upper plate of the housing 60, which cover the output terminals 62, 62 from above, except for the top portion. Between the left and right protective plates 63, 63, a pair of left and right protrusions 64, 64 are formed at predetermined intervals, spanning the upper and front surfaces of the housing 60. Between the protrusions 64, 64, a plate-shaped sealing element (here, a sponge) 65 is bonded vertically to the front surface of the housing 60. The seal 65 corresponds to the front rib 42 provided on the upper front wall 38 of the upper retaining wall 35. On the left and right sides of the housing 60, a pair of transverse ribs 66, 66 are provided in the vertical direction. The transverse ribs 66, 66 correspond to the grooves 44, 44 provided on the upper side walls 39A, 39B of the left and right sides of the upper retaining wall 35.
[0019] At the front of the housing 60, a pair of plate-shaped positive and negative switch-side terminals 67, 67 are arranged downwards. On the lower surface 8a of the switch 8, at the front of the housing 60, a horizontally elongated rectangular section 68 is formed downwards, enclosing the area containing the switch-side terminals 67, 67. The lower surface of the rectangular section 68 is flat. Inside the rectangular section 68, a partition plate 69 is arranged downwards between the left and right switch-side terminals 67, 67, separating the left and right sides of the rectangular section 68. The lower end of the partition plate 69 is on the same plane as the lower end of the rectangular section 68. A separate enclosed plate 70 is formed on the lower part of the front side of the rectangular section 68 within the front panel of the housing 60. After the switch-side terminals 67, 67 are installed inside the housing 60, the enclosed plate 70 is integrated with the front panel by vibration welding or the like. By installing the enclosure plate 70 in this way, the front surface of the housing 60 can be opened when assembling the switch-side terminals 67, 67, making the installation of the switch-side terminals 67, 67 easier. On the rear side of the square tube portion 68, the lower rear surface of the housing 60 is formed to be one layer higher than the lower end of the square tube portion 68, and a lower groove 71 is provided in the center in the left-right direction and along the front-back direction. The lower groove 71 corresponds to the bottom rib 49 provided on the upper assembly base 36.
[0020] A positioning plate 75 is provided on the upper side of the switch 8. The positioning plate 75 has a top view of a quadrilateral shape with a length slightly larger than the left and right width of the housing 60. A fitting recess 76 is formed on the lower surface along the front-back direction. The protrusions 64, 64 on the upper surface of the housing 60 fit into the fitting recess 76. A fitting rib 77 is formed in the fitting recess 76 along the front-back direction. The fitting rib 77 fits between the protrusions 64, 64. At the rear right end of the positioning plate 75, a threaded fastening piece 78 is provided facing rearward. A through hole 79 is formed on the threaded fastening piece 78. The through hole 79 corresponds to the upper threaded protrusion 37, and can be threaded fastened by a screw 80. On the left side of the threaded fastening piece 78, a rear abutment piece 81 is formed downward at the rear end of the positioning plate 75. The lower end of the rear abutment piece 81 can abut against the rear surface of the housing 60. On the left edge of the positioning plate 75, a downward-facing transverse abutment piece 82 is formed. The transverse abutment piece 82 can abut against the outer surface of the upper sidewall 39A on the left side of the upper retaining wall 35. A locking hole 83 is formed on the transverse abutment piece 82, which can lock the locking claw 45 provided on the upper sidewall 39A.
[0021] like Figure 3 As shown, the controller 9 has a housing 85, a circuit board 86, a terminal board 87, and a heat sink 88. The housing 85 has a lateral width between the left and right lower sidewalls 53A and 53B that are accommodated in the controller holding part 32. For example... Figure 7 and Figure 8 As shown, the housing 85 is a rectangular shape extending in the front-to-back direction when viewed from above. The housing 85 is a disc-shaped structure with its peripheral walls 89 facing downwards. Positioning plates 90, 90 are formed on the left and right outer surfaces of the peripheral walls 89. Each positioning plate 90 has a through hole 91, which corresponds to the threaded bosses 54, 54 provided on the lower side walls 53A, 53B. A recess 92 is formed in the center of the front portion of the upper surface of the housing 85. The recess 92 fits into the protrusion 55 provided on the mounting plate 28. The circuit board 86 has a width that is accommodated within the housing 85. Viewed from above, the circuit board 86 has a rectangular shape extending in the front-to-back direction. Control components such as capacitors and triacs are mounted on the lower surface of the circuit board 86. A speed dial 93 for the motor 6 is located on the lower rear surface of the circuit board 86.
[0022] Terminal block 87, made of resin, is assembled on the upper side of circuit board 86. A pair of power input terminals 94, 94 are mounted on the rear upper surface of terminal block 87. Power input terminals 94, 94 are used to connect power cable 10. Power input terminals 94, 94 are held in protective sleeves 95, 95 and protrude upwards, wherein protective sleeves 95, 95 are integrally formed with terminal block 87 and protrude upwards. Protective sleeves 95, 95 can pass through holes 47, 47 provided at the rear of mounting plate 28. Power input terminals 94, 94 are electrically connected to circuit board 86. Screws 96, 96 for connecting the power cable 10 are screwed onto the upper end of power input terminals 94, 94. In front of the power input terminals 94, 94, controller-side terminals 97, 97 are arranged on the terminal plate 87. The controller-side terminals 97, 97 are used to connect to the switch 8. The controller-side terminals 97, 97 are embedded in the resin front cylindrical portions 98, 98, with their upper ends forming the connection side of the switch 8. The upper end of each controller-side terminal 97 is a female terminal with a pair of front and rear terminal plates. The switch-side terminals 67 of the switch 8 are inserted between the terminal plates of the controller-side terminals 97 and make contact with each other. The lower ends of the controller-side terminals 97, 97 are electrically connected to the circuit board 86. The front cylindrical portions 98, 98 are sized to be inserted from below and fitted into the left and right sides of the square cylindrical portion 68 of the switch 8. The heat sink 88 is a metal plate that covers the portion of the circuit board 86 below, excluding the gear shift dial 93. The heat sink 88 is connected to the triac by screws, forming a thermal contact.
[0023] The controller 9 is molded, and with the circuit board 86, on which the terminal block 87 is mounted on the upper surface and the heat sink 88 is mounted on the lower surface, housed in the housing 85, resin 99 is filled inside the housing 85 at a position above the heat sink 88. The power input terminals 94, 94 and the controller-side terminals 97, 97 protrude upward from the upper surface 9a of the controller 9. A sponge-made elastic sheet 100 is provided on the upper surface 9a of the controller 9. The elastic sheet 100 is formed as a top-view quadrilateral covering the upper surface of the housing 85 between the power input terminals 94, 94 and the recess 92. The front cylindrical portions 98, 98 of the controller side terminals 97, 97 protrude upwards through the horizontally elongated clearance holes 101 formed on the elastic sheet 100. The clearance holes 101 are formed to be slightly smaller than the opening of the square cylindrical portion 68. Furthermore, the elastic sheet 100 is formed to be longer rearward in a manner that includes the area around the controller-side terminal 97. This is so that even if the switch 8 is installed with its front and rear orientations reversed, the switch-side terminals 67, 67 are moved rearward, and the controller-side terminal 97 is also formed on the rearward side, the elastic sheet 100 can still be configured in a reversed front-to-back configuration. In addition, the large area of the elastic sheet 100 also improves the sealing performance between it and the mounting plate 28.
[0024] Next, the assembly of switch 8 and controller 9 will be explained. The controller 9 has the heat sink 88 located on the lower side and the shift dial 93 located on the rear side, with the recess 92 of the housing 85 engaging with the protrusion 55 of the mounting plate 28 from below. Furthermore, the power input terminals 94, 94 pass through the holes 47, 47 of the mounting plate 28 from below, and the controller-side terminals 97, 97 pass through the through holes 48 from below. In actual operation, the mounting plate 28 is inverted, and the controller 9 is assembled onto it from above. Furthermore, the left and right positioning pieces 90, 90 are positioned in contact with the rear sides of the lower threaded bosses 54, 54 on the lower assembly base 51 of the mounting plate 28. Screws 102, 102, passing through the through holes 91, 91 of the positioning pieces 90, 90 from the rear, are screwed onto the lower threaded bosses 54, 54. Thus, as... Figure 3 , Figure 6 , Figure 11 As shown, the controller 9 is fixed to the lower mounting base 51 of the mounting plate 28. Figure 10 As shown, power input terminals 94 and 94 pass through holes 47 and 47 in the mounting plate 28 and protrude to the left and right outer sides of the partition ribs 46 and 46. Controller side terminals 97 and 97 protrude to the upper side of the mounting plate 28 through through holes 48.
[0025] With button 61 located at the rear and the transverse ribs 66, 66 of housing 60 engaged in the left and right grooves 44, 44 of upper retaining wall 35, switch 8 is pressed from above between the left and right upper side walls 39A, 39B. Thus, the lower rear surface of housing 60 is placed on upper mounting base 36, and the bottom rib 49 of upper mounting base 36 engages in the lower groove 71 of the lower surface of housing 60. Furthermore, the front rib 42 of upper front wall 38 engages between the protrusions 64, 64 of the front surface of housing 60. Therefore, as Figures 10-12 As shown, the square cylindrical portion 68 of the housing 60 is fitted into the through hole 48 of the mounting plate 28, and the front cylindrical portions 98, 98 of the controller-side terminals 97, 97 of the controller 9 protruding from the through hole 48 are inserted into the square cylindrical portion 68 from below. Therefore, the switch-side terminals 67, 67 are inserted and connected to the controller-side terminals 97, 97. However, the assembly order of switch 8 and controller 9 can also be reversed. In this state, with the protrusions 64, 64 engaged in the engagement recess 76 and the engagement rib 77 engaged between the protrusions 64, 64, the positioning plate 75 is placed over the upper surface of the housing 60, causing the locking claw 45 of the upper sidewall 39A on the left side to engage in the locking hole 83 of the transverse abutment piece 82. Then, the screw 80 is inserted from above into the through hole 79 of the threaded fastening piece 78 and screwed into the upper screw protrusion 37. Thus, the housing 60 is pressed down from above by the positioning plate 75, thereby being fixed to the upper assembly base 36.
[0026] At this time, the lower end of the square tube 68 presses against the elastic sheet 100 on the upper surface 9a of the controller 9, causing it to deform elastically. Therefore, the area around the connection between the switch-side terminals 67, 67 and the controller-side terminals 97, 97 is sealed by the tight contact between the square tube 68 and the elastic sheet 100. Meanwhile, on the front surface of the housing 60, the front rib 42 presses against the seal 65, causing it to elastically deform. Therefore, the portion between the front surface of the housing 60 and the upper front wall 38 is sealed between the left and right output terminals 62, 62 by the tight contact between the front rib 42 and the seal 65. The output terminals 62, 62 are connected to connectors 106, 105, 105, 105, 106 ... Figure 12 Each connector 106 is provided with an insulating cover 106a that covers the connection portion connected to the output terminal 62. The output terminals 62, 62 are divided by the front rib 42 and the seal 65 between them, and are covered by the protective plate portions 63, 63 above, so that short circuits caused by iron powder or the like are not easily generated. The power input terminals 94, 94 are electrically connected to a pair of cables of the power line 10, which is fixed to the line receiving part 33, by screws 96, 96. Since the power input terminals 94, 94 are also separated by the partition ribs 46, 46 and the protective sleeve parts 95, 95, it is not easy for short circuits caused by iron powder or the like to occur.
[0027] The switch button 7 is connected to a slide rod 107 extending in the front-rear direction on the left side of the upper retaining wall 35 inside the motor housing 3. The slide rod 107 has a pressing part 108 that bends to the right. The pressing part 108 protrudes upward into the upper retaining wall 35 via a notch 41 and is located behind the button 61 of the switch 8. When the slide rod 107 moves forward with a sliding operation of the switch button 7, the pressing part 108 presses the button 61. The slide rod 107 and the switch button 7 are forced towards the retracted position of the pressing part 108 when the button 61 is not pressed by a helical spring 109 disposed between them and the inner housing 25. The rear cover 4 covers the inner housing 25, which houses the switch 8 and controller 9, from the rear. At the point where the front end of the rear cover 4 overlaps with the rear end of the motor housing 3, a screw 110, penetrating the rear surface, is screwed into a boss 111 located on the rear surface of the mounting plate 28. Thus, the rear cover 4 is fixed to the inner housing 25. Multiple air inlets 112, 112… are formed on the rear surface, left and right sides, and lower surface of the rear cover 4.
[0028] In the grinding machine 1 with the above-described structure, the switch button 7 is slid forward. This causes the slide bar 107 to move forward, pressing the button 61 of the switch 8 with the pressing part 108, thus activating the switch 8. Consequently, the controller 9 drives the motor 6 to rotate the output shaft 14. The main shaft 5 then rotates via bevel gears 15 and 19, enabling grinding operations such as grinding to be performed by the top tool 24. As the fan 16 rotates with the output shaft 14, it draws in outside air through the air inlets 112 of the rear cover 4. A portion of the air drawn in through the air inlets 112 becomes an airflow that passes over the upper side of the mounting plate 28 and between the upper retaining wall 35 and the switch 8, before reaching the motor 6 through the vents 43, 43. Therefore, the switch 8 and the motor 6 are cooled. The air drawn in through the air inlets 112 on the lower surface becomes an airflow that reaches the motor 6 after passing through the heat sink 88. Therefore, the airflow is concentrated in contact with the heat sink 88, promoting heat dissipation of the controller 9 (especially the bidirectional thyristor). When the release switch 7 is slid forward, the slide bar 107 retracts under the force of the coil spring, thereby releasing the pressure on the button 61 by the pressing part 108. Therefore, the switch 8 is turned off, and the drive of the motor 6 stops.
[0029] Thus, the grinding machine 1 described above houses a motor 6, a controller 9, and a switch 8 within the rear cover 4 (outer shell). The controller 9 has a circuit board 86 and a controller-side terminal 97 electrically connected to the circuit board 86. The switch 8 has a switch-side terminal 67 electrically connected to the controller-side terminal 97. Furthermore, the controller-side terminal 97 is disposed on the upper surface 9a (the first opposing surface on the switch side) of the controller 9, and the switch-side terminal 67 is disposed on the lower surface 8a (the second opposing surface on the controller side) of the switch 8. The controller-side terminal 97 and the switch-side terminal 67 are in direct contact and electrically connected. An elastic sheet 100 (sealing body) is located between the upper surface 9a of the controller 9 and the lower surface 8a of the switch 8. This elastic sheet 100 is used to seal the area around the two terminals 97 and 67 when the controller-side terminal 97 and the switch-side terminal 67 are in direct contact. According to this structure, the upper surface 9a of the controller 9 and the lower surface 8a of the switch 8 can be ensured by the elastic sheet 100 through a simple assembly operation. Therefore, a high degree of sealing can be given to the electrical connection between the controller 9 and the switch 8, thereby effectively preventing short circuits.
[0030] In particular, an elastic sheet 100 is provided on the upper surface 9a of the controller 9, and a resin-made square tube portion 68 (tube portion) is provided on the lower surface 8a of the switch 8. The square tube portion 68 abuts against the elastic sheet 100 when the controller-side terminal 97 and the switch-side terminal 67 are in direct contact, thereby sealing the area around the two terminals 97 and 67. Therefore, the square tube portion 68 is in contact with the surface of the elastic sheet 100, thereby achieving high sealing performance. A resin front tube portion 98 (second tube portion) is provided on the upper surface 9a of the controller 9. The front tube portion 98 covers the periphery of the controller side terminal 97 and protrudes towards the square tube portion 68. When the controller side terminal 97 is in direct contact with the switch side terminal 67, the front tube portion 98 is inserted into the square tube portion 68. Therefore, the distance between the labyrinth seals at the contact points between the terminals can be increased, thereby improving the sealing performance. The square tube portion 68 and the front tube portion 98 are integrated with the controller 9 or the switch 8. Therefore, the positions of the front tube portion 98 and the square tube portion 68 are stable, and it is easy to insert the front tube portion 98 into the square tube portion 68. The square tube portion 68 and the front tube portion 98 cover the entire periphery of the controller-side terminal 97 or the switch-side terminal 67. Therefore, the controller-side terminal 97 and the switch-side terminal 67 are reliably protected.
[0031] The motor housing 3 (outer housing) has an inner shell 25 located between the switch 8 and the controller 9. A switch holding part 31 for holding the switch 8 is provided on the upper surface of the inner shell 25, and a controller holding part 32 for holding the controller 9 is provided on the lower surface. Furthermore, the square tube part 68 is inserted into the front tube part 98 through a through hole 48 provided in the inner shell 25. Therefore, the sealing of the electrical connection between the controller 9 and the switch 8 is improved, and the square tube 68 can also be positioned using the through hole 48. It is provided with an upper threaded protrusion 37, a positioning plate 75, and a screw 80 (switch positioning mechanism) for positioning the switch 8 in the inner housing 25. Therefore, switch 8 can be stably positioned without wobbling. The device includes a threaded boss 54, a positioning plate 90, and a screw 102 (controller positioning mechanism) for positioning the controller 9 within the inner housing 25. Therefore, the controller 9 can be positioned stably without shaking.
[0032] The switch 8 has a housing 60 and an output terminal 62 connected to the motor 6. A protective plate 63 (terminal protection part) is provided on the housing 60, which covers a part of the output terminal 62 in a non-contact manner. Therefore, it is possible to prevent short circuits between output terminals 62 and 62. The controller 9 has a pair of power input terminals 94, 94 that input power to the circuit board 86. Each power input terminal 94 has a protective sleeve 95 (protection part) for protecting the power input terminal 94, at least on the opposite side of each other. Therefore, it is possible to prevent short circuits between power input terminals 94 and 94. The sealing body is an elastic sheet 100 (sheet-shaped elastomer). Therefore, it can ensure a larger sealing surface and improve sealing performance.
[0033] The following explains the example of the change. In the above method, an elastic sheet is used as the sealing body installed in the controller housing, but the strip-shaped sealing body can also be configured as a square ring to surround the controller side terminals. The sealing body is not limited to sponge, and rubber or the like can also be used. In the above method, a square tube covers the area around the two switch-side terminals, but a square tube can also be provided for each switch-side terminal. In this case, each square tube can be inserted into the front tube of the controller-side terminal respectively. In the above method, a cylindrical part (square cylindrical part) is provided on the switch housing and a sealing body (elastic sheet) is provided on the controller housing. However, it is also possible to do the opposite, with a cylindrical part provided on the controller housing and a sealing body provided on the switch housing. The shape of the terminals is not limited to the above-described manner. The switch-side terminals may be female terminals, and the controller-side terminals may be male terminals. The cylindrical portion and the second cylindrical portion are not limited to square tubes as described above; they may also be cylindrical. They are not limited to covering the entire circumference of the terminals and may be shorter than the terminals. The first and second cylindrical sections can be omitted. For example, the controller may not have a housing, but rather the circuit board is covered with insulating material or partially mounted with a plate. In this case, the controller-side terminals are disposed on the surface of the controller formed on the switch side (first opposing surface). Similarly, the switch may not have a housing. In this case, the switch-side terminals are disposed on the surface of the switch formed on the controller side (second opposing surface). Therefore, a sealing body covering the periphery of the two terminals can be provided between the two opposing surfaces.
[0034] In the above configuration, the switch is positioned on the top and the controller on the bottom. However, it is also possible to reverse this configuration, with the switch positioned on the bottom and the controller on the top. Alternatively, the switch and controller can be positioned side-by-side. The switch can also be configured so that the button faces forward. The switch can be turned on / off via a pressing part of a slider, regardless of the button's orientation, or via a linkage that swings in conjunction with the slider. Alternatively, the switch can be turned on / off via the swinging of a lever, rather than by pressing a button. The shape of the enclosure is not limited to the above-mentioned methods. For example, a square cylindrical section can be integrally formed on the enclosure without a closing panel. The positioning mechanism of the switch is not limited to the positioning plate described above. The position and number of screws can be changed, or the housing can be directly threaded to the inner shell without using a positioning plate. Positioning is not limited to using screws; a locking piece located in the inner shell can also be used to lock the switch into place within the housing for positioning. The terminal protection portion of the output terminal is not limited to a protective plate portion that only covers the upper surface as described above. It can also be a semi-cylindrical or cylindrical portion that covers multiple surfaces of the output terminal. The terminal protection portion can also be omitted. The sealing between the output terminals can also be achieved by reversing the above method, using ribs on the enclosure side and seals on the inner shell side. The shapes of the ribs and seals can be modified appropriately. Alternatively, seals can be achieved by the abutting of the ribs without using seals. The sealing between the output terminals can also be omitted.
[0035] The positioning mechanism of the controller is not limited to the threaded protrusion and positioning plate described above. A threaded protrusion may also be provided on the housing, and a positioning plate may be provided on the controller retaining part. Similar to the case of a switch, positioning is not limited to using screws; a locking plate provided in the inner housing may also be used to lock the controller in place for positioning. The protective portion for the power input terminals is not limited to the protective sleeve described above. It may also be a wall covering only the opposing surfaces of the power input terminals, or the protective portion may be omitted. The power cord may also be electrically connected using components other than screws. The shape of the housing and circuit board is not limited to the above-described manner. It is not limited to a front-to-back extension shape, but can also be a left-to-right extension shape. Other shapes, such as a square viewed from above, can also be used. Besides changes in shape and position, the shift dial can also be omitted. The shape and position of the heat sink are not limited to the above embodiments. A heat sink may also be omitted.
[0036] Furthermore, the structure of the grinding machine is not limited to the above-described manner. A brushless motor can also be used. A braking mechanism for the output shaft can also be installed at the front of the motor housing. Power tools are not limited to grinders. This invention can also be applied to other power tools such as polishers, angle screwdrivers, and angle impact drivers. Power tools can be DC power devices that use batteries as their power source.
Claims
1. A power tool comprising a motor, a controller, and a switch housed within a housing, wherein the controller has a circuit board and a controller-side terminal electrically connected to the circuit board; the switch has a switch-side terminal electrically connected to the controller-side terminal, the controller-side terminal being disposed on a first opposing surface of the controller on the switch side, and the switch-side terminal being disposed on a second opposing surface of the switch on the controller side, the controller-side terminal and the switch-side terminal being in direct contact and electrically connected, characterized in that... A sealing body is provided between the first opposing surface and the second opposing surface. This sealing body seals the area around the two terminals when the controller-side terminal and the switch-side terminal are in direct contact. It has a cylindrical section and a second cylindrical section, wherein, The cylindrical portion, made of resin, is disposed on the second facing surface and covers the area around the switch-side terminals; the second cylindrical portion, made of resin, is disposed on the first facing surface and covers the area around the controller-side terminals, protruding towards the cylindrical portion side. The housing has an inner shell disposed between the switch and the controller. A switch holding part for holding the switch is provided on one surface of the inner shell, and a controller holding part for holding the controller is provided on the other surface. The cylindrical portion of either the first cylindrical portion or the second cylindrical portion is inserted into the other cylindrical portion via a through hole provided in the inner shell.
2. The power tool according to claim 1, characterized in that, The sealing body is disposed on the first opposing surface. The cylindrical portion abuts against the sealing body to seal the area around the two terminals while the controller-side terminal and the switch-side terminal are in direct contact.
3. The power tool according to claim 2, characterized in that, With the controller-side terminal in direct contact with the switch-side terminal, the second cylindrical portion is inserted into the cylindrical portion of the cylindrical portion.
4. The power tool according to claim 3, characterized in that, The cylindrical section and the second cylindrical section are integrated with the controller or the switch.
5. The power tool according to claim 3 or 4, characterized in that, The cylindrical portion and the second cylindrical portion cover the entire periphery of the controller-side terminal or the switch-side terminal.
6. The power tool according to claim 1, characterized in that, The sealing body is disposed on the second opposing surface. The cylindrical portion abuts against the sealing body to seal the area around the two terminals while the controller-side terminal and the switch-side terminal are in direct contact.
7. The power tool according to claim 6, characterized in that, With the controller-side terminal in direct contact with the switch-side terminal, the cylindrical portion is inserted into the cylindrical portion of the second cylindrical portion.
8. The power tool according to any one of claims 1-4, 6, and 7, characterized in that, A switch positioning mechanism is provided, which positions the switch within the inner housing.
9. The power tool according to any one of claims 1-4, 6, and 7, characterized in that, A controller positioning mechanism is provided, which positions the controller within the inner shell.
10. The power tool according to any one of claims 1-4, 6, and 7, characterized in that, The switch has a housing and an output terminal connected to the motor. A terminal protection section is provided on the housing, which covers a portion of the output terminal in a non-contact manner.
11. The power tool according to any one of claims 1-4, 6, and 7, characterized in that, The controller has a pair of power input terminals for supplying power to the circuit board. Each of the power input terminals has a protective portion for protecting the power input terminal, at least on the opposite surfaces of each other.
12. The power tool according to any one of claims 1-4, 6, and 7, characterized in that, The sealing body is a sheet-like elastomer.