Power tool

Abstract

The present invention provides a power tool that adopts a rear cover method to achieve shortening of the overall length and compactness in the radial direction of the motor housing. The driving drill (1) includes: a brushless motor (20) including a stator (21) and a rotor (22) capable of rotating relative to the stator (21); a cylindrical motor housing (8) that houses the brushless motor (20) and has a left housing (8a) and a right housing (8b); a grip portion connected to the lower part of the motor housing (8); a main shaft (41) disposed in front of the brushless motor (20) and driven by the brushless motor (20); and a rear cover (7) that supports the rear part of the rotor (22) and closes the rear part of the motor housing (8), and the rear cover (7) is fixed by being sandwiched between the left housing (8a) and the right housing (8b).

Description

Technical Field

[0001] The present invention relates to power tools such as driving drills. Background Art

[0002] Regarding power tools such as driving drills, the following power tools are known. A cylindrical motor housing extends in the front-rear direction. A motor is housed behind the motor housing, and an output part such as a main shaft is arranged in front of the motor housing by means of a speed reduction mechanism. In this case, the motor housing is formed by screwing together left and right split housings. As disclosed in Patent Document 1, for example, the rotating shaft of the motor has the following structure. That is, with respect to the split housing, a bearing support member separate from the split housing is screwed, and the rotating shaft of the motor is supported by a bearing supported by the bearing support member.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent No. 6537402 Gazette Summary of the Invention

[0006] If a separate bearing support member is used for screwing as in Patent Document 1, the assemblability deteriorates, and threaded fastening parts such as threaded bosses for mounting the bearing holding member need to be provided inside the motor housing. As a result, there is also a drawback that the motor housing becomes larger in the radial direction.

[0007] Therefore, an object of the present invention is to provide a power tool that adopts a rear cover method and is simple to assemble. Another object of the present invention is to provide a power tool that does not become larger in the radial direction.

[0008] To achieve the above object, in the present invention, a first invention is characterized by having: a motor including a stator and a rotor capable of rotating relative to the stator; a cylindrical motor housing that houses the motor and has a left housing and a right housing that are split left and right; a grip portion connected to the lower portion of the motor housing; an output portion provided in front of the motor and driven by the motor; and a rear cover that supports the rear portion of the rotor and closes the rear portion of the motor housing, and the rear cover is fixed by being sandwiched between the left housing and the right housing.

[0009] Another aspect of the first invention is characterized in that, on the basis of the above configuration, the rotor has a rotating shaft extending in the front-rear direction, and the rear cover holds a bearing that supports the rear end of the rotating shaft on the inner surface.

[0010] Another aspect of the first invention is characterized in that, in addition to the above-mentioned configuration, a fan is fixed to the rotating shaft in front of the bearing, and the bearing overlaps the fan in a radial direction of the bearing.

[0011] In order to achieve the above-mentioned purpose, in the present invention, the second invention is characterized in that it comprises: a motor, which includes a stator and a rotor capable of rotating relative to the stator; a cylindrical motor housing, which accommodates the motor and has a left housing and a right housing divided into left and right parts; a holding part, which is connected to the lower part of the motor housing; an output part, which is arranged in front of the motor and is driven by the motor; and a rear cover, which supports the rear of the rotor and closes the rear of the motor housing, the rear cover is clamped and fixed by the left housing and the right housing, and the bearing supporting the rear of the rotor overlaps with the motor side in the radial direction of the bearing.

[0012] Another aspect of the second invention is characterized in that, in addition to the above-mentioned configuration, the motor further includes a fan disposed behind the rotor, and the bearing overlaps the fan in a radial direction.

[0013] Another solution common to the first and second inventions is characterized in that, based on the above-mentioned structure, the rear cover is in the shape of a hood with an opening at the front, and a connecting piece sandwiched by the left and right shells is formed forward at the inner edge of the opening.

[0014] Another solution common to the first and second inventions is characterized in that, based on the above-mentioned configuration, a pair of left and right connecting pieces are provided.

[0015] Another solution common to the first and second inventions is characterized in that, in addition to the above-mentioned configuration, a protrusion protruding outward is formed on the outer peripheral surface of the connection piece, and a locking groove for locking the protrusion is formed on the inner surface of the motor housing.

[0016] Another means common to the first and second inventions is characterized in that, in addition to the above-mentioned configuration, the back surface of the rear cover forms a plane defined in the up-down and left-right directions.

[0017] Another aspect common to the first and second inventions is characterized in that, in addition to the above-mentioned configuration, a vent hole is formed on the peripheral surface of the rear cover.

[0018] Another means common to the first and second inventions is characterized in that, in addition to the above-mentioned configuration, the peripheral surface of the rear cover is continuously connected to the peripheral surface of the motor housing.

[0019] Another solution common to the first and second inventions is characterized in that, based on the above-mentioned structure, the rear cover is circular in a rear view.

[0020] Another common solution in the first and second inventions is based on the above configuration, and is characterized in that the rear cover is located at a position more forward than the rear end face of the motor housing.

[0021] Another common solution in the first and second inventions is based on the above configuration, and is characterized in that the left housing and the right housing are fixed by being fastened with screws.

[0022] According to the present invention, there is no need to provide a threaded fastening portion such as a threaded boss for installing the rear cover inside the motor housing. As a result, the assembly of the rear cover becomes simple. Additionally, as another effect, the overall length is shortened by adopting the rear cover, and the motor housing is also made more compact in the radial direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a perspective view of the driving drill of Solution 1 as viewed from the rear.

[0024] Figure 2 is a side view of the driving drill of Solution 1.

[0025] Figure 3 is a top view of the driving drill of Solution 1.

[0026] Figure 4 is a partial enlarged front view of the driving drill of Solution 1.

[0027] Figure 5 is a partial enlarged rear view of the driving drill of Solution 1.

[0028] Figure 6 is Figure 5 a cross-sectional view taken along line A - A of

[0029] Figure 7 is Figure 5 a cross-sectional view taken along line B - B of

[0030] Figure 8 is an exploded perspective view of a part of the housing and the gear assembly.

[0031] Figure 9 is Figure 6 an enlarged cross-sectional view taken along line C - C of

[0032] Figure 10 is Figure 6 an enlarged cross-sectional view taken along line D - D of

[0033] Figure 11 is a perspective view of the driving drill of Solution 2 as viewed from the rear.

[0034] Figure 12 is a partial enlarged rear view of the driving drill of Solution 2.

[0035] Figure 13Yes Figure 12 Cross-sectional view of the E-E line

[0036] Figure 14 Yes Figure 12 Cross-sectional view of the F-F line

[0037] Figure 15 Perspective view of the driving drill of Solution 3 as viewed from the rear

[0038] Figure 16 Partial enlarged rear view of the driving drill of Solution 3

[0039] Figure 17 Yes Figure 16 Cross-sectional view of the G-G line

[0040] Figure 18 Yes Figure 16 Cross-sectional view of the H-H line

[0041] Symbol Explanation

[0042] 1, 1A, 1B... driving drills; 2... main body; 3... gripping part; 4... drill chuck; 5... battery pack; 6... main body housing; 6a, 6b... half-split housings; 7, 7A, 7B... rear covers; 8... motor housing part; 8a... left housing; 8b... right housing; 8c... rear end face; 9, 71... screws; 10... bearing holding part; 12... connecting piece; 13... rib; 13a... groove; 14... rear rib; 15... front rib; 16... locking groove; 17, 67... threaded bosses; 20... brushless motor; 21... stator; 22... rotor; 31... rotating shaft; 32... bearing; 33... fan; 40... gear assembly; 41... main shaft; 50... first gearbox; 51... second gearbox; 52... gear cover; 53... clutch adjusting ring; 57... flange; 61... large diameter part; 62... medium diameter part; 63... small diameter part; 66... threaded fastening part; 68... protruding end; 75... reduction mechanism; 105... receiving groove. Detailed Implementation Manner

[0043] Hereinafter, embodiments of the present invention will be described based on the drawings.

[0044] [Solution 1]

[0045] Figure 1 Perspective view of the driving drill, which is an example of a power tool, as viewed from the rear Figure 2 Side view Figure 3 Top view Figure 4 Partial enlarged front view Figure 5 Partial enlarged rear view

[0046] The driving drill 1 includes: a main body 2 and a gripping portion 3. The main body 2 extends in the front-rear direction. The gripping portion 3 projects from the lower side of the main body 2. The main body 2 and the gripping portion 3 are in a T shape when viewed from either the left or right direction. A drill chuck 4 is provided at the front end of the main body 2. The front end of the drill chuck 4 can hold a drill bit.

[0047] A battery pack 5 as a power source is assembled at the lower end of the gripping portion 3. The housing of the driving drill 1 includes: a main body housing 6 and a rear cover 7. A cylindrical motor housing portion 8 and the gripping portion 3 are connected and provided on the main body housing 6. The main body housing 6 has left and right half-divided housings 6a, 6b. The half-divided housings 6a, 6b are fixed by a plurality of screws 9, 9... screwed in from the right side.

[0048] The rear cover 7 is in the shape of a cover with an open front surface. The outer periphery of the rear cover 7 is continuously connected to the outer periphery of the motor housing portion 8. The back surface 7a of the rear cover 7 becomes a plane defined in the up-down, left-right directions. As Figure 6 shown, a bearing holding portion 10 that is circular when viewed from the front is formed at the center of the inner surface of the rear cover 7. A plurality of exhaust ports 11, 11... are formed on the left and right side surfaces of the rear cover 7. As Figure 7 shown, a pair of connecting pieces 12, 12 are formed at the left and right inner edges of the opening of the rear cover 7. The connecting pieces 12, 12 are arranged left and right, but are connected at their respective lower portions. As Figure 8 shown, each connecting piece 12 has a shape that is arc-shaped when viewed from the front and extends forward. A protrusion 13 that projects radially outward is formed at the front end of each connecting piece 12. A concave groove 13a is formed circumferentially along the outer peripheral surface of the connecting piece 12 on the rear side of the protrusion 13.

[0049] The motor housing portion 8 is formed by assembling a left housing 8a and a right housing 8b that are the upper side portions of the half-divided housings 6a, 6b. The left housing 8a and the right housing 8b are assembled while sandwiching the connecting pieces 12, 12 of the rear cover 7. A rear end surface 8c that is orthogonal to the axial direction of the motor housing portion 8 is formed at the rear portion of the motor housing portion 8 slightly behind the last screw 9. As Figure 6 shown, a tongue piece portion 6c that extends rearward from the lower end of the rear end surface 8c is formed at the rear portion of the main body housing 6. The upper surface of the tongue piece portion 6c becomes a plane defined in the front-rear and left-right directions.

[0050] Again, as Figure 8 shown, on the left and right inner surface sides at the rear ends of the left housing 8a and the right housing 8b, a rear rib 14, a front rib 15, and a locking groove 16 are respectively formed in a semi-circular shape when viewed from the front. The rear rib 14 is locked in the concave groove 13a behind the protrusion 13 of the connecting piece 12. The front rib 15 receives the front surface of the connecting piece 12 and holds the stator 21 described later. The locking groove 16 is formed between the rear rib 14 and the front rib 15, so that, as Figure 9As shown, the protrusion 13 of the connecting piece 12 is engaged.

[0051] The protrusion 13 of each connecting piece 12 is engaged with the engaging groove 16, and each rear rib 14 is alternately engaged with the concave groove 13a, thereby preventing the rear cover 7 from falling off backward. In this state, it is clamped and fixed by the left and right outer casings 8a, 8b fastened by the screws 9. As Figure 6 and Figure 9 shown, the threaded bosses 17, 17 on the left outer casing 8a side for screwing in the last screw 9 are respectively provided above and below the connecting pieces 12, 12. Thus, by clamping the connecting pieces 12, 12 from left and right, the rear cover 7 can be reliably prevented from falling off. A retreating portion 7b for avoiding interference with the threaded bosses 17, 17 is formed on the front surface of the rear cover 7 and above the connecting pieces 12, 12.

[0052] A flat portion 18 is formed on the lower surface of the rear cover 7. The flat portion 18 abuts against the tongue piece portion 6c in the fixed state of the rear cover 7. Thus, the rear cover 7 is continuously connected to the motor housing portion 8 and the tongue piece portion 6c.

[0053] A brushless motor 20 is housed in the motor housing portion 8 at the rear part in the main body 2. The brushless motor 20 is an inner rotor type motor, which has: a stator 21 and a rotor 22, and the rotor 22 is disposed inside the stator 21. The stator 21 has: a stator core 23, front and rear insulators 24, 24, and a plurality of coils 25, 25... The coils 25, 25... are wound around the stator core 23 by means of the front and rear insulators 24, 24. Three fuse terminals 26, 26... are held below the front insulator 24. The fuse terminals 26 are fused with the coils 25 of each phase. By adopting the fuse terminals 26, a three-phase connection is formed. The connector 27 is fastened to the fuse terminal 26 by a screw from below. The connector 27 is connected to a controller described later through a wire.

[0054] A sensor circuit board 28 is mounted at the front end of the front insulator 24. A rotation detection element for detecting the magnetic field of a permanent magnet 30 described later is mounted on the sensor circuit board 28.

[0055] The rotor 22 has: a rotor core 29, and four permanent magnets 30, 30... A rotating shaft 31 is fixed to the axis of the rotor core 29. The permanent magnets 30, 30... are embedded in the through holes of the rotor core 29. The rear end of the rotating shaft 31 is axially supported by a bearing 32. The bearing 32 is held in the bearing holding portion 10 of the rear cover 7. A fan 33 is disposed in front of the bearing 32 and behind the rotor core 29. The fan 33 is a centrifugal fan and is fixed to the rotating shaft 31. The fan 33 and the bearing 32 overlap each other in the radial direction of the bearing 32. A plurality of air inlets 34, 34... are formed on the left and right of the stator 21 and on the left and right side surfaces of the motor housing portion 8 ( Figure 1 、2 ).

[0056] A gear assembly 40 is assembled in front of the brushless motor 20. The gear assembly 40 includes a spindle 41 protruding forward from a second gear box 51 described later. The drill chuck 4 is mounted on the front end of the spindle 41. A switch 42 is housed below the gear assembly 40 and on the upper part of the grip 3. A trigger 43 is connected to the front side of the switch 42. A forward / reverse switching button 44 for switching the rotation direction of the brushless motor 20 is provided above the switch 42. A light 45 for illuminating the front of the drill chuck 4 is provided in front of the forward / reverse switching button 44.

[0057] A battery mounting portion 46 is formed at the lower end of the grip portion 3. The battery pack 5 is slidably mounted on the battery mounting portion 46 from the front. The battery mounting portion 46 accommodates a terminal block and a controller (not shown). The controller includes a control circuit board on which a microcomputer, switching elements, etc. for controlling the brushless motor 20 are mounted.

[0058] The gear assembly 40 includes a cylindrical first gear box 50, a cylindrical second gear box 51, a gear cover 52, and a clutch adjustment ring 53. The first gear box 50, the second gear box 51, and the clutch adjustment ring 53 are all made of resin. The gear cover 52 is made of metal such as aluminum alloy. The clutch adjustment ring 53 can also be switched to a drilling mode.

[0059] The first gearbox 50 has a bearing holding portion 54 at the center of the rear end. The bearing holding portion 54 holds a bearing 55, and the bearing 55 supports the front part of the rotating shaft 31. The rotating shaft 31 protrudes into the first gearbox 50 and has a pinion 56 at the front end. A flange 57 is formed on the outer periphery of the front part of the first gearbox 50. Figure 7 and Figure 8 As shown, a pair of upper and lower first ribs 58, 58 extending in the front-to-back direction are respectively protruded behind the flange 57 and on the left and right of the first gear box 50. Semicircular receiving ribs 59, 59 are respectively formed on the left and right inner surfaces of the motor housing portion 8. In addition to receiving the bearing retaining portion 54, the receiving ribs 59, 59 also receive the rear surface of the first gear box 50. The outer periphery of the front surface of each receiving rib 59 is formed as a thick wall that is thicker than the inner periphery. First grooves 60, 60 for the first ribs 58, 58 to be locked are respectively formed in the thick wall portion. The first gear box 50 is restricted from rotating in the motor housing portion 8 by the locking of the first ribs 58, 58 and the first grooves 60, 60.

[0060] The second gearbox 51 has a multi-stage cylindrical shape with a large-diameter portion 61, a medium-diameter portion 62, and a small-diameter portion 63 coaxially arranged starting from the rear side. The large-diameter portion 61 covers the front end of the first gearbox 50, and the rear end of the large-diameter portion 61 is clamped to the flange 57. A snap ring 64 is held between the large-diameter portion 61 and the first gearbox 50. As Figure 7 and Figure 8 shown, on the front side of the large-diameter portion 61 and on the left and right of the medium-diameter portion 62, three second ribs 65, 65... are formed which project forward at a prescribed interval in the circumferential direction.

[0061] The gear cover 52 is annular. The gear cover 52 abuts against the front end of the motor housing portion 8 from the front. As Figure 4 shown, on the outer circumference of the gear cover 52, four threaded fastening portions 66, 66... are respectively provided and project at intervals in the circumferential direction. It should be noted that regarding the left and right intervals of the threaded fastening portions 66, 66, the upper two are close to each other and the lower two are separated. Each threaded fastening portion 66 projects to a position outside the clutch adjusting ring 53 when observed in the front view. As Figures 1 - 3 shown, on the outer circumference of the motor housing portion 8, threaded bosses 67, 67... are respectively formed behind each threaded fastening portion 66.

[0062] The inner circumference of the gear cover 52 becomes an annular protruding end portion 68 which projects toward the center side beyond the front end of the motor housing portion 8. The protruding end portion 68 abuts against the front surface of the large-diameter portion 61 of the second gearbox 51. As Figure 8 shown, three second grooves 69, 69... are formed on the left and right of the protruding end portion 68. As Figure 10 shown, the second ribs 65, 65... provided on the second gearbox 51 are respectively clamped to the second grooves 69, 69.... The rotation of the second gearbox 51 is restricted by the clamping of the second ribs 65 and the second grooves 69.

[0063] The clutch adjusting ring 53 has a cylindrical shape with the rear end covering the medium-diameter portion 62 of the second gearbox 51. The front end of the gear cover 52 faces the rear end of the clutch adjusting ring 53. It should be noted that the clutch adjusting ring 53 and the gear cover 52 can be in contact. At the front end of the small-diameter portion 63 of the second gearbox 51, a pressure plate 70 is fixed by three screws 70a, 70a.... The pressure plate 70 positions the clutch adjusting ring 53 from the front. Thus, the clutch adjusting ring 53 is held so as to be able to rotate between the gear cover 52 and the pressure plate 70.

[0064] The screws 71 respectively penetrate through the respective threaded fastening portions 66 of the gear cover 52 from the front. The screws 71 penetrating through the respective threaded fastening portions 66 are respectively screwed into the respective threaded bosses 67 of the motor housing portion 8. Thus, the gear assembly 40 is fixed to the motor housing portion 8. At this time, the protruding end portion 68 of the gear cover 52 presses the large-diameter portion 61 of the second gear box 51 rearward. Thus, the large-diameter portion 61 is pressed against the flange 57 of the first gear box 50. The first gear box 50 is pressed rearward by means of the flange 57 and abuts against the receiving rib 59 to be axially positioned.

[0065] In this way, by fastening the gear cover 52 with screws, the gear cover 52 is brought close to the receiving rib 59, whereby the second gear box 51 is in close contact with the first gear box 50.

[0066] A reduction mechanism 75 is provided inside the gear assembly 40. The reduction mechanism 75 is obtained by arranging the gear carriers 76A to 76C in parallel in the axial direction in three stages. The gear carrier 76A supports three planetary gears 78, 78,... respectively by means of pins 77. The gear carrier 76B also supports three planetary gears 78, 78,... respectively by means of pins 77. The gear carrier 76C also supports three planetary gears 78, 78,... respectively by means of pins 77. The planetary gears 78 at each stage perform planetary motion inside the internal gears 79A to 79C. The first-stage planetary gear 78 meshes with the pinion 56 of the rotating shaft 31. The second-stage internal gear 79B is arranged to be rotatable and axially movable inside the first gear box 50. The internal gear 79B is engaged with the engagement ring 64 in a state of meshing with the second-stage planetary gear 78 at the forward position to be restricted from rotating. The internal gear 79B meshes with the second-stage planetary gear 78 and the first-stage gear carrier 76A simultaneously at the rearward position to be rotatable. An annular groove 80 is formed over the entire circumference on the outer periphery of the internal gear 79B.

[0067] On the upper side of the outer periphery of the first gear box 50, a leaf spring 81 that is semicircular when viewed from the front is provided. As Figure 8As shown, the middle portions on the left and right of the leaf spring 81 are inserted through the support pins 82, 82 protruding from the left and right side surfaces of the first gearbox 50. Thus, the leaf spring 81 can swing back and forth about the support pins 82, 82. Locking pins 83, 83 are provided at the lower ends on the left and right of the leaf spring 81. The locking pins 83, 83 penetrate below the support pins 82, 82 and are inserted into the arc-shaped guide holes 84, 84 formed on the left and right of the first gearbox 50. The locking pins 83, 83 that penetrate the guide holes 84, 84 are locked to the annular groove 80 of the internal gear 79B. The center of the upper end of the leaf spring 81 is engaged with the lower surface of the front part of the slider 85. The slider 85 is arranged to be able to move back and forth on the upper side of the first gearbox 50. A speed change lever 86 is connected to the upper surface of the slider 85 by means of front and rear coil springs 87, 87. The speed change lever 86 is supported on the upper surface of the motor housing part 8 to be able to move back and forth. A recess 52a ([ Figure 6 , Figure 10 ) for allowing the slider 85 and the speed change lever 86 to slide forward is formed in the upper part of the rear surface of the gear cover 52.

[0068] When the speed change lever 86 is slid forward, the slider 85 advances. Then, the center of the upper end of the leaf spring 81 advances, and the lower ends on the left and right swing backward about the support pins 82, 82. Thus, the internal gear 79B moves backward by means of the locking pins 83, 83. This state is: the second-stage planetary gear 78 and the first-stage gear carrier 76A rotate integrally by means of the internal gear 79B and cancel the high-speed mode (2nd gear speed) of the second-stage reduction.

[0069] Conversely, when the speed change lever 86 is slid backward, the slider 85 retreats. Then, the center of the upper end of the leaf spring 81 retreats, and the lower ends on the left and right swing forward about the support pins 82, 82. Thus, the internal gear 79B moves forward by means of the locking pins 83, 83. This state is: the internal gear 79B is restricted from rotating by the engagement ring 64 so that the low-speed mode (1st gear speed) in which the second-stage reduction takes effect.

[0070] The third-stage internal gear 79C is arranged to be rotatable within the middle-diameter portion 62 of the second gearbox 51. A plurality of balls 90, 90... that abut against the front surface of the internal gear 79C are held within the middle-diameter portion 62. Each ball 90 engages with a not-shown locking projection provided on the front surface of the internal gear 79C in the rotational direction. Each ball 90 is biased rearward by means of a washer 91 through a plurality of disc springs 92, 92.... The front end of each disc spring 92 is held by a receiving ring 93 externally fitted to the small-diameter portion 63 of the second gearbox 51. The receiving ring 93 is locked by engaging with a plurality of grooves 94, 94... in the front-rear direction formed on the outer periphery of the small-diameter portion 63, thereby being restricted from rotating. Thus, the receiving ring 93 can only move in the front-rear direction. A feed ring 96 is disposed on the front side of the receiving ring 93. The feed ring 96 is screwed onto a threaded portion 95 provided on the outer periphery of the small-diameter portion 63. The outer periphery of the feed ring 96 engages with the inner periphery of the clutch adjusting ring 53. Thus, when the clutch adjusting ring 53 is rotationally operated, the feed ring 96 rotates integrally with the clutch adjusting ring 53 and performs a helical feed in the axial direction. Thereby, the receiving ring 93 moves back and forth, causing the pressing force of the disc spring 92 to change. The clutch adjusting ring 53 can vary the pressing force from the minimum to the maximum. In the case where the pressing force is maximum, even if the torque of the drill chuck 4 increases, the balls 90 cannot cross the locking projection of the internal gear 79C due to the pressing force of the disc spring 92. That is, in the case where the pressing force is maximum, it can be used as a drill in which the clutch does not operate.

[0071] The main shaft 41 is axially supported within the small-diameter portion 63 of the second gearbox 51 by a bearing 97A (ball bearing) and a bearing 97B (metal bearing). The rear end of the main shaft 41 is loosely inserted into the third-stage gear carrier 76C. Three claws 98, 98... are protrudingly provided in front of the gear carrier 76C. Each claw 98 engages with the outer periphery of the main shaft 41. Thus, the main shaft 41 rotates integrally with the gear carrier 76C.

[0072] Three wedge pins 99, 99... are disposed between the claws 98, 98. Each wedge pin 99 abuts against three chamfered portions 100, 100... formed on the outer periphery of the main shaft 41. When the drill chuck 4 is rotated for drill bit disassembly and assembly in the stopped state of the brushless motor 20, each wedge pin 99 enters between the claw 98 and the chamfered portion 100, thereby locking the rotation of the main shaft 41.

[0073] In the driving drill 1 configured as described above, an operator presses the trigger 43 to turn on the switch 42. By turning on the switch 42, the microcomputer of the controller turns on and off each switching element and starts energizing the coil 25. By energizing the coil 25, the stator 21 generates a magnetic field. Using this magnetic field, the rotor 22 rotates.

[0074] The rotation detection element of the sensor circuit board 28 outputs a rotation detection signal indicating the position of the permanent magnet 30. Through this output, the microcomputer of the controller obtains the rotation state of the rotor 22. The microcomputer controls the ON / OFF of each switching element according to the obtained rotation state. Through the ON / OFF of the switching element, current flows through the coils 25 of each phase of the stator 21 in sequence. Thereby, the rotor 22 continues to rotate, and the rotation of the rotor 22 causes the rotation shaft 31 to rotate. The rotation of the rotation shaft 31 causes the pinion 56 to rotate, and the rotation of the pinion 56 causes the main shaft 41 to rotate via the reduction mechanism 75. Thereby, operations such as screw fastening can be performed using the drill bit held by the drill chuck 4.

[0075] When the torque of the main shaft 41 increases and exceeds the pressing force of the disc spring 92 that restricts the rotation of the internal gear 79C by means of the ball 90, the ball 90 relatively crosses over the locking projection on the front surface of the internal gear 79C, causing the internal gear 79C to rotate idly. Thereby, the rotational transmission toward the main shaft 41 is cut off. The clutch operating torque can be changed by the rotational operation of the clutch adjusting ring 53.

[0076] The driving drill 1 of the above-mentioned solution 1 includes a brushless motor 20 (motor), and the brushless motor 20 includes a stator 21 and a rotor 22 that can rotate relative to the stator 21. In addition, the driving drill 1 includes: a cylindrical motor housing portion 8 (motor housing) that houses the brushless motor 20 and has a left housing 8a and a right housing 8b that are divided left and right; and a grip portion 3 that is connected to the lower portion of the motor housing portion 8. In addition, the driving drill 1 includes: a main shaft 41 (output portion) that is provided in front of the brushless motor 20 and is driven by the brushless motor 20; and a rear cover 7 that supports the rear portion of the rotor 22 and closes the rear portion of the motor housing portion 8. And, the rear cover 7 is fixed by being sandwiched between the left housing 8a and the right housing 8b.

[0077] According to this configuration, it is not necessary to provide a threaded fastening portion such as a threaded boss for installing the rear cover 7 inside the motor housing portion 8. Thereby, the overall length is shortened by adopting the rear cover 7, and moreover, the compactness in the radial direction of the motor housing portion 8 can be achieved. In addition, no screws for installing the rear cover 7 are required, making the assembly simple, and thus the manufacturing cost is also reduced.

[0078] In particular, here, the rotor 22 has a rotation shaft 31 that extends in the front-rear direction, and the rear cover 7 holds the bearing 32 that supports the rear end of the rotation shaft 31 on the inner surface. Thereby, the bearing 32 can be held with good accuracy in the radial direction.

[0079] A fan 33 is fixed to the rotation shaft 31 on the front side of the bearing 32, and the bearing 32 overlaps the fan 33 in the radial direction of the bearing 32.

[0080] Thus, even if the fan 33 is provided, the rear cover 7 can be formed to be shorter in the front-rear direction, which is effective in shortening the overall length.

[0081] The rear cover 7 is in the shape of a front-opening cover, and a connecting piece 12 sandwiched by the left and right outer shells 8a and 8b is formed on the front inner edge of the opening. Thus, the rear cover 7 can be reliably clamped and fixed by the connecting piece 12.

[0082] A pair of left and right connecting pieces 12 are provided. Thus, the rear cover 7 can be clamped and fixed by the left and right outer shells 8a and 8b with good balance.

[0083] A protrusion 13 protruding outward is formed on the outer peripheral surface of the connecting piece 12, and a locking groove 16 for locking the protrusion 13 is formed on the inner surface of the motor housing portion 8. Thus, the clamped and fixed rear cover 7 can be reliably prevented from falling off backward.

[0084] The back surface of the rear cover 7 becomes a plane defined in the up-down, left-right directions. Thus, the front-rear dimension of the rear cover 7 is shortened.

[0085] By tightening the gear cover 52 with screws, the gear cover 52 is brought close to the receiving rib 59, and the second gear box 51 is closely attached to the first gear box 50. By this close attachment, the first gear box 50 and the second gear box 51 are not separated. If they are separated, it cannot be used as the aforementioned drill. This is because: even if the clutch adjusting ring 53 is rotated to maximize the pressing force of the disc spring 92, the ball 90 will cross the locking protrusion.

[0086] Next, another embodiment of the present invention will be described. However, except for the shape of the rear cover and its fixing structure, it is the same as the above Embodiment 1. Thus, the same reference numerals are given to the same components, and repeated descriptions are omitted.

[0087] [Embodiment 2]

[0088] In Figures 11 - 14 In the driving drill 1A shown, the tongue piece portion that abuts against the lower surface of the rear cover 7A as in Embodiment 1 is not provided on the main body housing 6. Thus, the entire circumference of the rear end surface 8c of the motor housing portion 8 becomes a plane. A hanging portion 7c replacing the tongue piece portion is integrally formed at the lower part of the rear cover 7A in place of the flat portion.

[0089] In the driving drill 1A, it is not necessary to provide a threaded fastening portion such as a threaded boss for installing the rear cover 7A inside the motor housing portion 8. Thus, by adopting the rear cover 7A, the overall length is shortened, and furthermore, the compactness in the radial direction of the motor housing portion 8 can be achieved. In addition, since screws for installing the rear cover 7A are not required, the assembly becomes simple, and thus the manufacturing cost is also reduced.

[0090] [Embodiment 3]

[0091] Figures 15 - 18 In the drive drill 1B shown, the rear part of the motor housing 8 is formed to be long, and the rear end surface 8c is located behind the fan 33. On the rear side of the fan 33 and on the inner surfaces of the left and right housings 8a and 8b along the circumferential direction, receiving grooves 105 and 105 are respectively formed in a semicircular shape.

[0092] The rear cover 7B is a plate body that is circular when viewed from the front, rather than a cover shape. A bearing holding portion 10 is provided at the center of the front surface of the rear cover 7B. The rear cover 7B is clamped by the left and right housings 8a and 8b by being fitted across the receiving grooves 105 and 105. Thus, the rear cover 7B is located at a position more forward than the rear end surface 8c of the motor housing 8 and is not exposed when viewed from the side. Exhaust ports 11 and 11... are formed on the left and right side surfaces of the motor housing 8 outside the fan 33.

[0093] In the drive drill 1B, it is not necessary to provide a threaded fastening portion such as a threaded boss for installing the rear cover 7B inside the motor housing 8. Thus, by using the rear cover 7B, the overall length is shortened, and furthermore, the compactness in the radial direction of the motor housing 8 can be achieved. In addition, since there is no need for screws for installing the rear cover 7B, the assembly becomes simple, and thus the manufacturing cost is also reduced. Moreover, since the rear cover 7B is located at a position more forward than the rear end surface 8c of the motor housing 8, the overall length is further shortened.

[0094] Hereinafter, modification examples will be described.

[0095] In Solutions 1 and 2, the connecting pieces of the rear cover are not limited to a pair on the left and right. The circumferential width can be reduced and the number can be increased. The length can also be changed. On the outer peripheral surface of the connecting piece, protrusions can be provided instead of ridges. The number of combinations of ridges and the like with the locking groove can be increased. Conversely, the concave groove can be eliminated, and only one combination of ridges and the like with the locking groove can be used to prevent detachment.

[0096] In Solution 3, the structure of clamping the rear cover by providing a receiving groove on the inner peripheral surface of the rear end of the motor housing is not limited either. For example, according to the thickness of the rear cover, a receiving groove can be provided on the outer peripheral surface of the rear cover, and a ridge or protrusion that is locked to the receiving groove can be provided on the inner peripheral surface of the rear end of the motor housing.

[0097] In each solution, the motor can be a commutator motor or the like instead of a brushless motor.

[0098] In each solution, the left housing and the right housing can not be semi-separated. The motor housing portion and the holding portion can be connected separately.

[0099] In each embodiment, the bearing held by the rear cover is not limited to a structure overlapping with the fan. For example, when the fan is located on the front side of the rotor, the bearing may also overlap radially with an insulator on the motor side or the like. However, the bearing and the motor side do not necessarily have to overlap. When the fan is on the front side, an air inlet can be provided in the rear cover as a vent port.

[0100] In each embodiment, the number of stages of the speed reduction mechanism can be increased or decreased. The speed change mechanism can also be redesigned, or the speed change mechanism can be omitted. An electric clutch can be used instead of a mechanical clutch.

[0101] The electric tool claimed in the present invention is not limited to a driving drill. In addition to being applicable to a driving drill, the present invention is also applicable to electric tools such as a vibration driving drill having a vibration mechanism, an impact screwdriver, and a screwdriver. These electric tools can be AC tools that use an AC power supply instead of a battery pack.

Claims

1. An electric tool, characterized in that, it has: a motor including a stator and a rotor capable of rotating relative to the stator; a cylindrical motor housing that houses the motor and has a left housing and a right housing divided left and right; a grip portion connected to the lower portion of the motor housing; an output portion provided in front of the motor and driven by the motor; and a rear cover that supports the rear portion of the rotor and closes the rear portion of the motor housing, the rear cover is fixed by being sandwiched between the left housing and the right housing, the rear cover is in the shape of a front-opening cover, and a connecting piece sandwiched between the left housing and the right housing is formed forward on the inner edge of the opening, a protrusion protruding outward is formed on the outer peripheral surface of the connecting piece, and a locking groove for locking the protrusion is formed on the inner surface of the motor housing.

2. The electric tool according to claim 1, characterized in that, the rotor has a rotating shaft extending in the front-rear direction, and the rear cover holds a bearing that supports the rear end of the rotating shaft on the inner surface.

3. The electric tool according to claim 2, characterized in that, a fan is fixed to the rotating shaft on the front side of the bearing and the bearing overlaps the fan in the radial direction of the bearing.

4. An electric tool, characterized in that, it has: a motor including a stator and a rotor capable of rotating relative to the stator; a cylindrical motor housing that houses the motor and has a left housing and a right housing divided left and right; a grip portion connected to the lower portion of the motor housing; an output portion provided in front of the motor and driven by the motor; and a rear cover that supports the rear portion of the rotor and closes the rear portion of the motor housing, the rear cover is fixed by being sandwiched between the left housing and the right housing, a bearing that supports the rear portion of the rotor overlaps the motor side in the radial direction of the bearing, the rear cover is in the shape of a front-opening cover, and a connecting piece sandwiched between the left housing and the right housing is formed forward on the inner edge of the opening, a protrusion protruding outward is formed on the outer peripheral surface of the connecting piece, and a locking groove for locking the protrusion is formed on the inner surface of the motor housing.

5. The electric tool according to claim 4, characterized in that, the motor further has: a fan disposed behind the rotor, the bearing overlaps the fan in the radial direction.

6. The electric tool according to any one of claims 1 to 5, characterized in that, there are a pair of left and right connecting pieces provided.

7. The electric tool according to any one of claims 1 to 5, characterized in that, the back surface of the rear cover becomes a plane defined in the up-down, left-right directions.

8. The electric tool according to any one of claims 1 to 5, characterized in that, ventilation openings are formed on the peripheral surface of the rear cover.

9. The electric tool according to any one of claims 1 to 5, characterized in that, the peripheral surface of the rear cover is continuously connected to the peripheral surface of the motor housing.

10. The power tool according to any one of claims 1 to 5, characterized in that, the rear cover is circular when viewed from the rear.

11. The power tool according to any one of claims 1 to 5, characterized in that, the rear cover is located at a position more forward than the rear end surface of the motor housing.

12. The power tool according to any one of claims 1 to 5, characterized in that, the left housing and the right housing are fixed by being fastened with screws.

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