CN110815138B

CN110815138B - Electric tool

Info

Publication number: CN110815138B
Application number: CN201810906022.2A
Authority: CN
Inventors: 内田洋树; 曹健
Original assignee: Hitachi Koki Co Ltd
Current assignee: Koki Holdings Co Ltd
Priority date: 2018-08-10
Filing date: 2018-08-10
Publication date: 2024-02-02
Anticipated expiration: 2038-08-10
Also published as: JP6863415B2; CN110815138A; JP2020026029A

Abstract

The invention provides an electric tool, which realizes miniaturization of a shell by applying effort to a supporting structure of an inner cover and a gear ring. The electric tool has a reduction mechanism for decelerating the rotation of a motor, and a housing for housing the motor and the reduction mechanism, wherein a planetary gear reduction mechanism having a ring gear (35) located outside a planetary gear is used as the reduction mechanism, and an inner cover (20) for supporting a reduction mechanism bearing is held between the motor and the reduction mechanism through the housing. The inner cover (20) has a recess (38) protruding in the axial direction, and the ring gear has a protrusion (25) corresponding to the recess, and the ring gear (35) is held so as not to rotate in the circumferential direction relative to the housing by engaging these protrusions.

Description

Electric tool

Technical Field

The present invention relates to an electric power tool that realizes miniaturization of the apparatus itself by improving the mounting structure of a planetary gear reduction mechanism and a bearing holding portion of a motor.

Background

Electric tools that rotate a tool bit by decelerating the rotational force of a motor and driving a power transmission mechanism are known, and as one example, impact drive, impact wrench, and hydraulic drive are widely used. For example, in an impact tool, a rotational force is transmitted to a hammer, and the anvil is struck by the hammer, so that the rotational force of a motor is converted into an intermittent striking force in a rotational direction, and a bolt or the like is fastened by a tip tool using the striking force. When the wrench for pulling the switch of the impact tool is pulled, the motor is driven, and the spindle is rotated by the reduction mechanism. The reduction mechanism is a mechanical device that reduces an input rotational speed generated by a motor using a plurality of gears and outputs the reduced rotational speed. Torque proportional to the reduction ratio can be obtained by the reduction mechanism. When the spindle rotates, the hammer coupled to the spindle rotates by a cam mechanism using a hammer case and a cam roller. When the hammer rotates, the striking claw of the hammer and the blade portion (struck claw) of the anvil transmit rotational force, and the anvil rotates. The screw and the bolt are fastened by a nose tool such as a hexagonal wrench mounted on the nose of the anvil in the axial direction, for example, by forming a mounting portion of the nose tool.

In the case of performing a screw tightening operation on wood, the hammer rotates (continuously rotates) with the anvil during a certain time period from the start of tightening. Then, when the reaction torque generated in the screw gradually increases according to the progress of tightening, and the reaction torque exceeds the spring pressure of the hammer spring, the hammer gradually retreats toward the motor side while gradually compressing the hammer spring along the shapes of the anvil cam groove and the hammer cam groove. By the retraction of the hammer, the contact length (engagement amount) in the front-rear direction of the striking claw of the hammer and the struck claw of the anvil becomes smaller. When the engagement amount of the striking claw of the hammer with the struck claw of the anvil is 0, the engagement of the hammer with respect to the anvil with respect to the rotation direction is released. When the striking claw of the hammer retreats and passes over the struck claw of the anvil, the hammer is pushed out toward the distal tool side by the compression force of the hammer spring and collides with the next struck claw of the anvil, thereby applying a strong striking force to the anvil. In this way, the striking claw provided on the hammer and the struck claw provided on the anvil repeatedly perform the operations of disengagement, advance, and striking (striking operations) before the fastening of the screw is completed.

Prior art literature

Patent document 1: japanese patent laid-open No. 2002-355767

A conventional electric tool such as an impact drive uses a planetary gear reduction mechanism as a reduction mechanism. At this time, the main shaft bearing and the ring gear of the planetary gear reduction mechanism are coaxially supported by the inner cover. The support structure of the ring gear in patent document 1 is a structure that supports an outer peripheral surface of the ring gear on an inner peripheral surface of an inner cover, which is located on an outer peripheral side of the ring gear. That is, the ring gear is accommodated by the inner cover. As such, as a structure in which the inner cover is located radially outward of the ring gear, the apparatus main body becomes larger in the outer peripheral portion of the inner cover than the ring gear in the radial dimension.

Disclosure of Invention

The present invention has been made in view of the above circumstances, and an object thereof is to provide an electric power tool in which the size of a housing is reduced and the size is reduced by applying effort to a support structure for an inner cover and a ring gear.

Another object of the present invention is to provide an electric power tool in which an outer peripheral portion of an inner cover is supported by an inner peripheral surface of a ring gear of a planetary gear reduction mechanism, and a housing is directly located on an outer peripheral surface side of the inner cover.

Another object of the present invention is to provide a core alignment electric tool capable of aligning the rotation center of a spindle and the rotation center of a ring gear with high accuracy by an inner cover.

The invention disclosed in this application is described in terms of the following if representative structural features are described.

According to one feature of the present invention, an electric power tool includes a motor, a reduction mechanism that reduces rotation of the motor, and a housing that houses the motor and the reduction mechanism, wherein the reduction mechanism includes a planetary gear, a ring gear positioned outside the planetary gear, and a sun gear positioned inside the ring gear and connected to the motor, and is disposed so as to hold a bearing that supports the reduction mechanism between the motor and the reduction mechanism via the housing, and an outer peripheral surface of an inner cover is supported by an inner peripheral surface of the ring gear. In other words, a part of the inner cover is housed on the inner peripheral side of the ring gear. The inner cover is an integrally formed product, and the outer peripheral surface is supported by the inner peripheral surface of the ring gear.

According to another feature of the present invention, the ring gear is made of metal or synthetic resin, a gear portion is formed on the inner side, a cylindrical portion extending in the axial direction adjacent to the gear portion is formed, and a part of the inner cover is accommodated on the inner side of the cylindrical portion. The inner cover includes a concave-convex portion protruding or recessed in the radial direction, and the ring gear includes a concave-convex portion having a convex-concave shape corresponding to the concave-convex portion, and the concave-convex portion is engaged with the concave-convex portion to prevent relative rotation between the ring gear and the inner cover. The plurality of concave-convex portions and the plurality of concave-convex portions are respectively arranged.

According to another feature of the invention, the rotation shaft of the motor is arranged coaxially with the rotation center of the reduction structure. The inner cover is fixed to one of the motor bearings for supporting the rotation shaft and one of the gear bearings of the shaft support reduction mechanism, and includes a first cylindrical portion for holding an outer peripheral surface of the motor bearing and a second cylindrical portion for holding an outer peripheral surface of the gear bearing. The housing is constituted by a synthetic resin member which is divided by a dividing surface including a rotation axis of the motor, and the inner cover is sandwiched by the housing so as to intersect the dividing surface, and the inner cover and the housing form a rotation stopper so as not to rotate relative to each other. The housing is formed by a cup-shaped metal case that houses a power transmission mechanism that converts the output of the speed reducer into the driving force of the front end tool, and the ring gear is disposed in an axial alignment with the opening edge of the metal case so as to have the same diameter as the opening edge.

Effects of the invention

According to the present invention, since the inner cover is not located radially outward of the outer peripheral surface of the ring gear, the radial dimension of the housing of the power tool can be made to be the minimum dimension required for housing the ring gear, and the power tool can be miniaturized. Further, since the outer peripheral surface of the inner cover is held on the inner peripheral surface of the ring gear, the rotation shaft of the main shaft and the central axis of the ring gear can be coaxially maintained, and the rotation accuracy can be ensured. Further, since the concave-convex portion formed on the main shaft side and the concave-convex portion formed on the inner cover side are engaged, the inner cover held by the outer case so as not to rotate in the rotational direction can be used to prevent the ring gear from rotating.

Drawings

Fig. 1 is a side view of an impact tool 1 according to an embodiment of the invention.

Fig. 2 is a longitudinal sectional view showing the internal structure of the impact tool 1 of the embodiment of the present invention.

Fig. 3 is an enlarged view of a portion B in fig. 2.

Fig. 4 is a perspective view of the inner cover 20 and the ring gear 35 in fig. 2.

Fig. 5 is a view in a state where the inner cover 20 and the ring gear 35 in fig. 2 are assembled, where (a) is a front view, (B) is a view seen from the direction E of (a), and (C) is a view seen from the direction F of (a).

Fig. 6 (a) is a C-C cross-sectional view in fig. 5 (a), and (B) is a D-D cross-sectional view in fig. 5 (a).

Fig. 7 is a perspective view of an inner cover 20A and a ring gear 35A of an impact tool according to a second embodiment of the present invention.

Fig. 8 is a view in which the inner cover 20A in fig. 7 is assembled with the ring gear 35A, (a) is a front view, (B) is a C-C sectional view in (a), and (C) is a D-D sectional view in (a).

Fig. 9 is a perspective view of an inner cover 20B and a ring gear 35B of an impact tool according to a third embodiment of the present invention.

Fig. 10 is a view showing a state in which the inner cover 20B and the ring gear 35B in fig. 9 are assembled, wherein (a) is a front view, (B) is a C-C sectional view in (a), and (C) is a D-D sectional view in (a).

Fig. 11 is an enlarged view of the vicinity of an inner cover 20C and a ring gear 35C of an impact tool according to a fourth embodiment of the present invention.

Fig. 12 is a perspective view of the inner cover 20C and the ring gear 35C in fig. 11.

Fig. 13 is a view showing a state in which the inner cover 20C in fig. 11 is assembled with the ring gear 35C, (a) is a front view, (B) is a C-C sectional view in (a), and (C) is a D-D sectional view in (a).

Fig. 14 is a perspective view of an inner cover 20D and a ring gear 35D of an impact tool according to a fifth embodiment of the present invention.

Fig. 15 is a diagram showing a state in which the inner cover 20D in fig. 14 is assembled with the ring gear 35D, where (a) is a front view, (B) is a C-C sectional view in (a), and (C) is a D-D sectional view in (a).

In the figure: 1-an impact tool, 2-a main body casing, 2 a-a body part, 2 b-a handle part, 2 c-a battery mounting part, 3-a hammer case, 4-a motor, 4 b-a stator core, 4 c-a rotary shaft, 5a, 5 b-an insulator, 6-a trigger switch, 6 a-a trigger lever, 6D-a plunger, 7-a forward/reverse rotation switching lever, 8a, 8 b-a bearing, 9 a-a bearing, 9 b-a bearing, 11-a sensor substrate, 13-a cooling fan, 14-a control circuit substrate, 15-a rib, 16 a-a power line, 16 b-a signal line, 17 a-an air suction port, 17 b-an air discharge port, 18a to 18 h-a bolt, 19a to 19 h-a bolt boss, 20A to 20D-an inner cover, 21-a first cylindrical part, 21 a-an opening part, 21 b-a bearing holding surface, 22-a connecting part, 23-a second cylindrical part, 23 b-a bearing holding surface, 24-extending portion, 24 a-outer peripheral surface 24 b-protruding portion, 25a, 25 b-recessed portion, 26-notched portion, 28-switch button, 29-light emitting mechanism, 30-speed reducing mechanism, 31-sun gear, 32-planetary gear, 35-ring gear, 36-gear portion, 37-cylindrical inner surface, 38 c-notched portion, 39a, 39b, 39D-protruding portion, 40-striking mechanism, 41-spindle, 42-hammer, 42a, 42 b-striking claw, 43-hammer spring, 44-stopper ring, 46-fitting hole, 47-planetary gear carrier portion, 50-anvil, 51a, 51 b-blade portion, 52-mounting hole, 60-front tool holding portion, 61-sleeve, 62-steel ball, 63-compression spring, 65-limited stepped portion, 100-battery, 101-release switch, A1— (axis of rotation shaft).

Detailed Description

Example 1

Embodiments of the present invention are described below with reference to the drawings. In the following description, the directions of up, down, left, right, front and rear are described as directions shown in the drawings. An embodiment which is an electric power tool in this embodiment is represented by an impact tool 1.

Fig. 1 is a side view of an impact tool 1 according to an embodiment of the invention. The impact tool 1 uses a rechargeable battery 100 as a power source, uses a motor as a driving source to drive a rotary striking mechanism, and converts rotation of a rotary member into intermittent striking force in a rotation direction by the rotary striking mechanism to drive a tip tool holding portion 60 connected to the striking mechanism portion. The main body case 2 is composed of three parts, namely a body part 2a formed cylindrically, a handle part 2b as a part to be held by an operator with one hand, and a battery mounting part 2c for mounting the detachable battery 100. The handle portion 2b extends downward so as to be substantially orthogonal to a central axis (rotation axis A1) of the body portion 2a, and an operation handle (actuation lever 6 a) for controlling a trigger switch (described later in fig. 3) for turning on or off the motor is provided at a position where an index finger is located when the operator grips the motor. A forward/reverse rotation switching lever 7 for switching the rotation direction of the motor is provided above and rearward of the start lever 6 a.

The lower portion in the handle portion 2b is formed with a battery mounting portion 2c for mounting the battery 100. The battery mounting portion 2c is an enlarged diameter portion formed so as to be widened in the radial direction (orthogonal direction) from the longitudinal center of the handle portion 2b, and the battery 100 is mounted on the lower side of the battery mounting portion 2c. The battery 100 is a rechargeable battery such as a lithium battery, and is a pack type in which a plurality of cells are housed in a battery case. The battery 100 can be taken out from the main body casing 2 by being moved forward while pushing the release button 101. The power supply of the impact tool 1 of the present embodiment may be any power supply that uses a commercial power supply via an AC power cable. The main body case 2 is made of synthetic resin in a two-part form on the left and right, and is bolted by a plurality of bolts 18a to 18 h.

An air intake port 17a formed as a plurality of slits is disposed on the side surface of the body 2a and on the rear side, and a plurality of air discharge ports 17b are disposed at a position spaced apart from the air intake port 17a by a predetermined distance on the front side. The air outlet 17b is provided on the front side of the motor 4. The anvil 50 is exposed on the front side of the body 2a, and a distal end portion of the anvil 50 is provided with a distal end tool holding portion 60 for holding a distal end tool to be attached.

Fig. 2 is a longitudinal sectional view showing the internal structure of the impact tool 1 of fig. 1. The external appearance of fig. 1 is not identical to that of fig. 2, but it is different from that of fig. 2 only in whether or not this includes a change in design, and the internal structure of the impact tool 1 in fig. 1 is the same as that shown in fig. 2 to 15. The housing of the impact tool 1 is composed of a main body housing 2 (2 a, 2b, 2 c) made of synthetic resin and a metal hammer case 3 housing the striking mechanism 40. A plurality of bolt bosses 19a to 19h for bolt fastening are formed on one side (left side) of the main body casing 2. The hammer case 3 is formed in a cup shape with a thin tip, and has an opening on the rear side and a small opening (through hole) through which the anvil 50 passes through at the bottom center on the front side. The hammer case 3 is fixed by being sandwiched between the front sides of the left and right divided main body cases 2. The motor 4, the reduction mechanism 30 using a planetary gear, and the striking mechanism 40 are arranged coaxially with the rotation axis A1 on the cylindrical body portion 2a of the main body case 2.

The trigger switch 6 is provided at an upper portion in the handle portion 2b integrally extending substantially at right angles from the body portion 2a of the main body case 2, and a trigger lever 6a as an operation portion is exposed from the trigger switch 6 to the front side of the main body case 2. The trigger switch 6 includes a housing in which a switching mechanism is incorporated, and an operating portion (trigger lever 6 a) provided outside for driving the switching mechanism, and the trigger lever 6a and the switching mechanism are connected by a plunger 6d, and the plunger 6d is moved in and out to turn on and off the switch. The switch mechanism inside the housing is disposed in the closed space, and the trigger lever 6a is pulled into the body case 2 to pull the coupled plunger 6d into the housing, thereby turning on the trigger switch 6. The trigger switch 6 may have any form or structure, and may be provided with a swing type trigger lever that swings around a swing axis, for example, in addition to the slide type trigger lever 6 a.

A control circuit board 14 having a function of controlling the speed of the motor 4 by the pulling operation of the trigger lever 6a is also housed in the handle portion 2 b. The control circuit board 14 is disposed in the vertical direction so as to be parallel to the central axis of the handle portion 2 b. A microcomputer (hereinafter referred to as a "microcomputer") not shown and a semiconductor switching element (not shown) for forming a conversion circuit are mounted on the control circuit board 14. The semiconductor switching element can be configured using six FET (Field effect transistor). The battery mounting portion 2c is a portion formed so as to be expanded radially (in the orthogonal direction) from the longitudinal center axis of the handle portion 2b, and the battery 100 is mounted on the lower side thereof. A switch button 28, such as a switch for switching the operation mode, is provided on the outer upper surface of the battery mounting portion 2c. A light emitting mechanism 29 for irradiating a target object to be worked by a tip tool, not shown, is provided in front of the switch button 28. As the light emitting means 29, a light emitting diode is used here. The switch button 28 is provided with various operation buttons such as a setting button for the striking strength, an irradiation switch of the light emitting mechanism 29, and a remaining amount inspection button of the battery 100, and a display lamp or the like corresponding to the operation buttons.

The motor 4 is driven by exciting current generated by a conversion circuit using a brushless DC motor. The rotation shaft 4c of the motor 4 is disposed such that its axis A1 extends in the longitudinal direction of the body 2 a. The stator of the motor 4 is constituted by a stator core 4b formed by laminating cores and forming a plurality of pole pieces, an insulator 5a of a non-conductive body attached to the front side of the stator core 4b, an insulator 5b of a non-conductive body attached to the rear side of the stator core 4b, and a coil (not shown) wound with the insulators 5a, 5b. A rotor, not shown, forms a magnetic circuit with permanent magnets housed in the laminated core. The motor 4 (stator core 4 b) is supported by ribs 15 extending from the inside of the main body case 2 (body portion 2 a) toward the motor 4 side.

A cooling fan 13 for cooling the motor 4 is provided axially rearward of the motor 4 and coaxially with the rotary shaft 4 c. The rotation shaft 4c is supported by a bearing 8a located on the front side and a bearing 8b located on the rear side of the stator core 4b, and the cooling fan 13 is disposed between the bearing 8b and the stator core 4 b. The cooling fan 13 rotates in synchronization with the motor 4, and when the cooling fan 13 rotates, outside air is taken in from an air intake port 17a (see fig. 1) on the rear side of the main body casing 2, the motor 4 is cooled, and the outside air is discharged from an air discharge port 17b, not shown.

The sensor substrate 11 is disposed axially forward of the motor 4 between the stator core 4b and the bearing 8 a. The sensor board 11 is a device equipped with three magnetic force detection means (not shown) for detecting the magnetic field of the permanent magnet included in the rotor, and is formed of an annular printed board. As the magnetic force detection means, a plurality of (e.g., three) hall ICs can be mounted at predetermined intervals on positions facing the permanent magnets of the rotor using commercially available hall ICs. The sensor board 11 is used for connecting a power line 16a and a signal line 16b to a coil of the motor 4. The motor 4 is a star-shaped wire, and a coil end portion, not shown, wound around the insulators 5a and 5b is connected to a wiring pattern of the sensor substrate 11 by soldering.

The speed reduction mechanism 30 is configured to reduce the output of the motor 4 at a predetermined speed reduction ratio and transmit the reduced output to the main shaft 41, and here, a speed reduction mechanism having a planetary gear is used. As will be described later with reference to fig. 3, the detailed structure of the speed reduction mechanism 30 is such that a spindle cam groove, not shown, is formed in the outer peripheral surface of the spindle 41, and a carrier portion of the speed reduction mechanism 30 is formed on the rear side of the shaft portion of the spindle 41. The main shaft 41 is manufactured by integrally molding a metal in view of strength.

The hammer 42 is disposed on the outer peripheral side of the shaft portion of the main shaft 41, and a hammer cam groove, not shown, is formed on the inner peripheral side. The hammer 42 is held by a cam mechanism using steel balls, and the outer peripheral surface of the spindle 41 is in contact with a part of the inner peripheral surface of the hammer 42. In fig. 2 and 3, the cam mechanism is shown in a cross-sectional position in which it is not visible. When the reaction force received from the tip tool is low, the hammer 42 rotates so as to be interlocked with the rotation of the spindle 41, but when the reaction force received from the tip tool is large, the relative position of the hammer 42 and the spindle 41 in the rotation direction slightly fluctuates due to the cam ball movement of the cam mechanism, not shown, and the hammer 42 moves greatly rearward. Since the hammer 42 is always urged forward by the hammer spring 43 with respect to the spindle 41, the movement of the hammer 42 rearward moves while compressing the hammer spring 43. The front side of the hammer spring 43 abuts against the hammer 42, and the rear side abuts against the carrier portion 47 of the main shaft 41.

On the rear end of the anvil 50, two blade portions 51 (51 a, 51 b) as hit portions are formed at positions spaced apart by 180 degrees in the circumferential direction. The blade 51 is shaped to extend radially outward and is struck by the striking claws 42a and 42b of the hammer 42. The side surfaces of the blade portions 51a and 51b in the rotation direction form both the surface to be struck when the hammer 42 rotates in the tightening direction and the surface to be struck when the hammer is rotated in the unscrewing direction, which are formed on opposite sides thereof. The main shaft 41 and the rotary body of the anvil 50 are axially supported on the front side by the inner wall of the hammer case 3 via a bearing 9a, and are axially supported on the rear side by the inner cover 20 via a ball bearing 9 b.

The distal tool holding section 60 includes a mounting hole 52 having a hexagonal cross-sectional shape extending axially rearward from the distal end of the anvil 50, two hole portions formed at two positions in the circumferential direction and penetrating in the radial direction for disposing the steel balls 62, and a sleeve 61 provided on the outer peripheral side. A compression spring 63 for urging the sleeve 61 to the rear side is attached to the inside of the sleeve 61.

Fig. 3 is a partial enlarged view of the portion B surrounded by the circular frame in fig. 2. The reduction mechanism 30 includes a sun gear 31 fixed to the front end of the rotary shaft 4c of the motor 4, a ring gear 35 provided on the outer peripheral side of the sun gear 31 so as to surround the sun gear at a distance, and a plurality of planetary gears 32 arranged in a space between the sun gear 31 and the ring gear 35 and engaged with both gears. The ring gear 35 is also called external teeth, and a gear is formed on the inner peripheral surface of the annular member. The ring gear 35 is configured to be held on its outer peripheral surface by the main body case 35, and the ring gear 35 itself does not rotate. The ring gear 35 has the same diameter as the opening edge of the hammer case 3, and the front end surface of the ring gear 35 contacts the rear end of the hammer case 3 and the rear end surface is held in the front-rear direction so as to contact the front of the defining step 65 formed in the body 2a of the main body case 2. That is, the ring gear 35 is sandwiched between the main body case 2 and the hammer case 3 in the axial direction.

A sun gear 31 is fixed to the tip of the rotary shaft 4c of the motor 4. The sun gear 31 is a spur gear as an input portion of the reduction mechanism 30. A plurality of (three in this case) planetary gears 32 are arranged between the outer peripheral gear surface of the sun gear 31 and the inner peripheral gear surface of the ring gear 35. The three planetary gears 32 are axially supported by a carrier portion 47 formed at the rear end portion of the main shaft 41, and the planetary gears 32 revolve around the sun gear 31 while rotating around an axis (not shown) axially supported by the carrier portion 47. The ring gear 35 itself does not rotate. When the rotation shaft 4c of the motor 4 rotates, the sun gear 31 also rotates in synchronization therewith. The rotational force of the sun gear 31 is decelerated at a predetermined ratio and transmitted to the carrier portion 47, and thus the main shaft 41 rotates. A fitting hole 46 is formed in the axial center of the rear side (motor 4 side) of the main shaft 41 as a receiving space for the sun gear 31.

The inner cover 20 is a member integrally formed of synthetic resin, and is held by the body 2a of the main body case 2 so as to be sandwiched from the left-right direction. At this time, the inner cover 20 is provided with a protruding portion 25 protruding radially outward so that the inner cover 20 does not rotate relative to the main body case 2 (see fig. 4 described later). Since one (18 b) of the plurality of bolt bosses is provided at the upper portion of the inner cover 20, the inner cover 20 is stably held by the main body casing 2. The main function of the inner cover 20 is to coaxially center the rotation shaft 4c of the motor 4 with the rotation center of the main shaft 41 while maintaining the two bearings 8a and 9 b. The bearing 8a held by the inner cover 20 is used to axially support the rotary shaft 4c of the motor 4, such as with a ball bearing. The bearing 9b held by the inner cover 20 is a rear end for shaft supporting the main shaft 41, such as using a ball bearing.

The ring gear 35 has an axial length extending rearward (toward the inner cover 20) from the planetary gears 32, and an extension 24 of the inner cover 20 is disposed inside the ring gear. By disposing the inner cover 20 inside the ring gear 35 in this manner, the inner cover 20 is centered with high accuracy. The inner cover 20 is manufactured by integrally molding synthetic resin such as plastic, but may be manufactured by light metal such as aluminum alloy. The ring gear 35 is made of iron-based metal, but may be made of a molded product of synthetic resin. In the present embodiment, the rotation of the inner cover 20 is stopped inside the body portion 2a of the main body case 2. The rotation of the ring gear 35 is stopped by the inner cover 20. By fixing in this manner, since there is no need to dispose a structural member for stopping rotation of the ring gear 35 on the outer peripheral side of the ring gear 35, the body portion 2a of the main body casing 2 can be formed slim, and an increase in size of the striking tool 1 can be suppressed. Further, since the two bearings 8a and 9b are held by the inner cover 20, the positioning accuracy of the rotation shafts of the inner cover 20 and the reduction mechanism 30 can be improved.

In the single body of the ring gear 35, the rotation is not stopped with respect to the body portion 2 a. The inner cover 20 is held in a state where the ring gear 35 and the body 2a are relatively movable, not firmly held by the body 2 a. A carrier portion 47 formed at the rear end portion of the main shaft 41 is housed inside the ring gear 35. The carrier 47 is configured to axially support two parallel disk parts extending radially outward from the center, and the planetary gear 32 that is disposed between the disk parts and rotates between the disk parts using its shaft. A stepped stopper ring 44 is interposed between the carrier portion 47 and the hammer spring 43 on the front side of the carrier portion 47.

Fig. 4 is a perspective view of the inner cover 20 and the ring gear 35. The inner cover 20 is provided with a first cylindrical portion 21 and a second cylindrical portion 23, the first cylindrical portion 21 forming a cylindrical surface of the bearing 8a for holding the motor 4 on the inner peripheral side, and the second cylindrical portion 23 forming a cylindrical surface of the bearing 9b for holding the rear end portion of the shaft support main shaft 41 on the inner peripheral side. The first cylindrical portion 21 and the second cylindrical portion 23 are connected by a disk-shaped connecting portion 22 extending in the radial direction, and are formed as a unitary structure. An extension 24 extending radially outward in a disk shape is also formed radially outward from the rear end of the second cylindrical portion 23. The outer periphery of the extension 24 is formed to have an outer peripheral surface 24a having a predetermined width in the axial direction, and the inner cover 20 and the ring gear 35 are disposed coaxially with the rotation axis A1 of the motor 4 by the contact of the outer peripheral surface 24a with the cylindrical inner surface 37 of the ring gear 35. The front end of the first cylindrical portion 21 is an opening 21a through which the rotary shaft 4c of the motor 4 passes while the bearing 8a is pressed. A bearing holding surface 21b having a stepped shape is formed at the inner rear end of the first cylindrical portion 21 so that the pressed bearing 8a does not move rearward and the inner diameter thereof is reduced.

The ring gear 35 is an internal gear in which a gear portion 36 is formed continuously in the circumferential direction on the inner peripheral surface. A cylindrical inner surface 37, on which the gear portion 36 is not formed, is formed on one side in the axial direction of the ring gear 35. The cylindrical inner surface 37 is a surface against which the outer peripheral surface 24a of the extension 24 abuts, except for a part (cutout portion 38) which is continuous in the circumferential direction. Since the cylindrical inner surface 37 is provided for holding the extension 24 of the inner cover 20, the length in the direction of the rotation axis A1 is the minimum required and is almost the same as the axial width of the outer peripheral surface 24 a. Concave portions or convex portions for stopping rotation are formed in the inner cover 20 and the ring gear 35, respectively. For the purpose of stopping, any of the concave portion and the convex portion is provided on either side of the inner cover 20 and the ring gear 35, and here, the protruding portion 25 as a convex portion is formed on the inner cover 20 side and the cutout portion 38 as a concave portion is formed on the ring gear 35 side. The protruding portion 25 protrudes radially outward from the outer peripheral surface 24a, and a part of the protruding portion on the rear side thereof is located in the notch 38. In this way, the protrusion 25 abuts against the notch 38, and thus the relative rotation between the inner cover 20 and the ring gear 35 is prevented.

The protruding portion 25 of the inner cover 20 not only prevents relative rotation with the ring gear 35, but also functions to prevent relative rotation with the main body casing 2. The protruding portion 25 is a member formed to be large so as to protrude radially outward from the second cylindrical portion 23, and is provided at two positions 180 degrees apart from the rotation axis A1 as a reference. One side of the protruding portion 25 is positioned by two ribs formed on one side inner wall surface of the divided main body casing 2, and the other side of the protruding portion 25 is positioned by two ribs formed on the other side inner wall surface of the divided main body casing 2.

Fig. 5 is a diagram of a state in which the inner cover 20 and the ring gear 35 are assembled, in which (a) is a front view, (B) is a view from the direction E in (a) (left side view), and (C) is a view from the direction F in (a) (bottom view). As seen in the drawing of (a), the radially outer edge position of the protruding portion 25 is the same position as the outer edge position of the ring gear 35, and the front-view outer edge shape is the same position as the outer peripheral surface of the ring gear 35. Thus due to the inner partThe cover 20 does not protrude to the outer side than the outer peripheral surface of the ring gear 35, so that the outer diameter of the body portion 2a of the main body case 2 can be suppressed from becoming large, and the main body case 2 can be miniaturized. Diameter D of inner side of first cylinder portion 21 ₅ Almost the same size as the outer ring of the bearing 8 a. Since the outer peripheral surface 24a of the extension 24 abuts against the inner peripheral surface of the ring gear 35, the ring gear 35 and the inner cover 20 can be kept in a good contact state without rattling.

Fig. 5 (B) shows the dimensions of the respective portions of the inner cover 20 and the ring gear 35. The diameter of the outer side of the ring gear 35 is D ₁ The diameter of the inner side is D ₂ (refer to fig. 5 (a)). Therefore, the outer diameter of the portion of the inner cover 20 excluding the extension 24 of the protruding portion 25 is also D ₂ . On the other hand, the outer diameter D of the first cylinder portion 21 ₃ An outer diameter D of the second cylindrical portion 23 ₄ Is small. In the view in the direction F of FIG. 5 (C), the largest outer diameter of the inner cover 20 is the protruding portion 25, the outer diameter D1 of which is equal to the outer diameter D of the ring gear 35 ₁ Equal. In this way, since the outer diameter of the assembly of the inner cover 20 and the ring gear 35 is the diameter D1 even at a certain position in the circumferential direction and does not exceed the size of the ring gear 35, the ring gear 35 having the largest size can be used within the size range limited by the body portion 2a of the main body case 2.

Fig. 6 (a) is a C-C cross-sectional view of fig. 5 (a), and fig. 6 (B) is a D-D cross-sectional view of fig. 5 (a). As understood herein, in the C-C section, the extension 24 is located inboard of the ring gear 35. Therefore, since the outer peripheral surface of the extension portion 24 is held by the inner peripheral surface of the ring gear 35, the loosening of the inner cover 20 and the ring gear 35 can be effectively suppressed, and centering of the rotation center of the rotation shaft 4c of the motor 4 and the ring gear 35 can be achieved with high accuracy. On the other hand, in the D-D section, the ring gear 35 and the protruding portion 25 are arranged in the axial direction, and the left-right width of the protruding portion 25 is equal to the left-right width of the ring gear 35, so that the dimension in the left-right direction can be suppressed in the left-right width of the ring gear 35. The second cylindrical portion 23 includes a bearing holding surface 23b for supporting the bearing 9 b.

As described above, according to the present embodiment, since the connection structure between the inner cover 20 and the ring gear 35 is changed so that the outer edge portion of the inner cover 20 is brought into contact with the inner peripheral side of the ring gear 35, the inner cover 20 can be constituted to be small, and as a result, the outer diameter of the body portion 2a of the main body case 2 can be formed to be small. Further, since the inner cover 20 includes the convex portion protruding in the radial direction and the ring gear 35 includes the concave portion corresponding to the convex portion, the relative rotation between the ring gear 35 and the inner cover 20 can be prevented by the engagement of these portions, and therefore, it is not necessary to stop the rotation of the ring gear 35 by the housing. Further, since the axial direction (front-rear direction) of the ring gear 35 is fixed by being sandwiched between the restriction step surface of the main body case 2 and the hammer case 3 not inside the hammer case 3, the ring gear 35 having the same diameter as the maximum diameter of the hammer case 3 can be used.

Example 2

Fig. 7 is a perspective view of the vicinity of the inner cover 20A and the ring gear 35A of the impact tool of the second embodiment of the present invention. The basic structure is the same, in particular, in terms of the inner shaft side of the ring gear 35A holding the extension 24 of the inner cover 20A, but the concave-convex structure for the rotation stop of the inner cover 20A and the ring gear 35A is opposite to that of the first embodiment. That is, the protruding portion 39a protruding axially forward is formed on the ring gear 35A, and the recess 25A for accommodating the protruding portion 39a is formed on the protruding portion 25 of the inner cover 20A. In this way, the concave portion 25A for preventing relative rotation and the convex portion (protruding portion 39 a) can be formed on the ring gear 35A side on the inner cover 20A side. Even in the structure of the second embodiment, the structure in which the outer peripheral surface 24a of the extension portion 24 abuts against the cylindrical inner surface 37 of the ring gear 35A is the same as that of the first embodiment. The second embodiment is characterized in that since the notch portion is not formed on the ring gear 35A side but the protruding portion 39a is formed, the ring can be prevented from being lowered in rigidity due to the notch being formed.

Fig. 8 is a diagram of a state in which the inner cover 20A is assembled with the ring gear 35A, (a) is a front view, (B) is a C-C sectional view in (a), and (C) is a D-D sectional view in (a). In the C-C section, the extension 24 is located inside the ring gear 35A, and the outer peripheral surface of the extension 24 is in contact with the inner peripheral surface of the ring gear 35A, so that the loosening of the inner cover 20A and the ring gear 35A can be effectively suppressed, and the centering of the rotation center of the rotation shaft 4C of the motor 4 and the ring gear 35A can be performed with high accuracy. On the other hand, in the D-D section, since the protruding portion 39a of the ring gear 35A is fitted into the recessed portion 25A of the protruding portion 25, not only the circumferential positioning of the ring gear 35A can be performed, but also the rattling can be suppressed. In the D-D section, the ring gear 35A and the protruding portion 25 are arranged in the axial direction, and the axial length of the inner cover 20A is the same as that of the first embodiment, so that the electric power tool can be prevented from being enlarged.

According to the second embodiment, since the outer edge portion of the inner cover 20A is brought into contact with the inner peripheral side of the ring gear 35A, the inner cover 20A can be constituted smaller as in the first embodiment. Further, since the structure in which the ring gear 35A is fixed by being sandwiched between the main body case 2 and the hammer case 3 in the axial direction (the front-rear direction) is the same, it is not necessary to store the ring gear 35A inside the hammer case 3, and therefore, it is possible to use the ring gear 35A having the same diameter as the maximum diameter of the hammer case 3, and it is possible to realize a planetary gear reduction mechanism having a large size relative to the hammer case 3.

Example 3

Fig. 9 is a perspective view of an inner cover 20B and a ring gear 35B of an impact tool according to a third embodiment of the present invention. The basic structure is the same as that of the second embodiment shown in fig. 7 and 8, except that the protruding portion 39B formed in the ring gear 35B is long in the axial direction (front-rear direction), and the concave portion 25B formed in the protruding portion 25 of the inner cover 20B is continuous from the axial rear end to the front end of the protruding portion 25. As another insight, the concave portion 25b is not formed from the axially rear end of the protruding portion 25 to the front side, but may be formed so as to be recessed from the radially outer surface to the radially inner side. If so formed, since the portion (contact surface) where the concave portion 25B of the inner cover 20B and the protruding portion 39B of the ring gear 35B are in contact in the circumferential direction becomes large, the rigidity against rotation can be made stronger than in the second embodiment.

Fig. 10 is a diagram in which the inner cover 20B is assembled with the ring gear 35B, (a) is a front view, (B) is a C-C sectional view in (a), and (C) is a D-D sectional view in (a). As shown in fig. 10 (B), in the C-C section, the cross-sectional shapes of the inner cover 20B and the ring gear 35B are the same as those of the inner cover 20A and the ring gear 35A shown in the second embodiment. On the other hand, it can be understood that the length of the ring gear 35B is greatly increased in the D-D end face as shown in fig. 10 (C) compared with the ring gears 35, 35A of the first and second embodiments. In the third embodiment, since the front-rear length of a portion passing through the left and right side surfaces of the ring gear 35B becomes large, the contact area with the main body casing 2 made of synthetic resin increases, and therefore the ring gear 35B can be held more stably by the main body casing 2.

Example 4

Fig. 11 is an enlarged view of the vicinity of an inner cover 20C and a ring gear 35C of an impact tool according to a fourth embodiment of the present invention. The basic structure is the same as that of the first embodiment shown in fig. 3, and the upper and lower ends (the projection 24b described later in fig. 12) of the inner cover 20C are not in contact with the inner periphery of the ring gear 35C but in contact with the main body casing 2 when viewed in the longitudinal cross-sectional position. The holding method of the inner cover 20C is the same as that of the inner cover 20 of the first embodiment, and the second cylindrical portion 23 is sandwiched by the restricting step portion 65 formed inside the housing 2. In addition, the radially inner wall surface of the restriction step portion 65 is in contact with or adjacent to the extension portion 24.

Fig. 12 is a perspective view of an inner cover 20C and a ring gear 35C of a feeding tool according to a fourth embodiment of the present invention. The inner cover 20C has a structure in which a protruding portion 24b protruding in the up-down direction is added to the extending portion 24 of the inner cover 20 of the first embodiment. On the other hand, since the cutout portions 38C fitted to the protruding portions 24b are added to the ring gear 35C side, a total of 4 concave portions of the cutout portions 38C arranged at the upper and lower positions are formed in the ring gear 35C in addition to the two cutout portions 38 arranged at the left and right sides. The 4 concave portions (the cut portions 38, 38C) are fitted to the 4 convex portions (the protruding portions 24b, 25) formed on the inner cover 20C side.

Fig. 13 is a view showing a state in which the inner cover 20C and the ring gear 35C are combined, in which (a) is a front view, (B) is a C-C cross-sectional view in (a), and (C) is a D-D cross-sectional view in (a). As shown in fig. 13 (B), the cross-sectional shapes of the inner cover 20C and the ring gear 35C are the same diameter even in the C-C section. As shown in fig. 13 (C), the inner cover 20C and the ring gear 35C have the same diameter in cross section even in the D-D cross section. In this way, since the number of concave-convex portions for stopping rotation of the ring gear 35C and the inner cover 20C is increased, the ring gear 35C can be stably held so as not to rotate relative to the main body casing 2.

Example 5

Fig. 14 is an enlarged view of the vicinity of an inner cover 20D and a ring gear 35D of an impact tool according to a fifth embodiment of the present invention. The basic consideration is to make the number of concave-convex portions formed on the inner cover 20D side protruding or recessed in the radial direction four and the number of concave-convex portions formed on the ring gear 35D side four, which is close to the idea of the fourth embodiment. Here, four protruding portions 39D protruding toward the axial forward side are formed on the ring gear 35D side. Further, a cutout 38 is formed in a portion between the adjacent protruding portions 39d, where the cylindrical inner surface 37 is not formed. The protruding portion 39d is a shape extending horizontally in the left-right direction, and is a slightly larger protruding portion 39d protruding inward than the gear portion 36. On the other hand, the inner cover 20D side is formed with four cutout portions 26 that cut the extension portion 24 largely in the left-right direction. The feature of this shape is that the protruding portions 39d are fitted in the cutout portions 26 so that the four protruding portions 39d form a part of the protruding portion 25 and are located on both sides in the circumferential direction of the protruding portion 25. As a result, not only the protruding portion 25 but also the protruding portions 39D located on both sides in the circumferential direction thereof are fitted into the recessed portions (not shown) formed in the inner peripheral surface of the main body casing 2, and the ring gear 35D can be stably held because the same structure as the ring gear 35D is prevented from rotating even with respect to the main body casing 2.

Fig. 15 is a diagram showing a state in which the inner cover 20D is assembled with the ring gear 35D, (a) is a front view, (B) is a C-C sectional view in (a), and (C) is a D-D sectional view in (a). As shown in fig. 15 (B), in the C-C section, the outer diameter of the inner cover 20D is the same diameter as the inner peripheral surface of the ring gear 35D. In the D-D section, as shown in fig. 15 (C), the inner cover 20D has the same diameter as the ring gear 35C in cross-sectional shape, but the inner cover 20D does not protrude radially outward from the ring gear 35C. In this way, since the number of the concave-convex portions for stopping rotation of the ring gear 35D and the inner cover 20D is increased, the ring gear 35D can be stably held so as not to be rotated with respect to the main body casing 2. Since the total front-rear length of the ring gear 35D and the inner cover 20D is the same as that of the first to fourth embodiments, the entire size of the assembly of the inner cover 20D and the ring gear 35D does not increase even if the ring gear 35D is stopped with respect to the main body casing 2. The height of the protruding portion 25 of the inner cover 20D in the up-down direction is H ₁ (the dimension is the same as H of FIG. 5 (A)) ₁ The same) and the total height of the additional protrusions 39d in the up-down direction is H ₂ If in H ₂ And the height H of the protruding portion 25 of the first embodiment ₁ The height (length in the circumferential direction) of the protruding portion 25 is made smaller to H in the same manner ₂ ＝H ₁ The inner cover 20 and the ring gear 35 of the impact tool 1 used in the first embodiment can be replaced with the inner cover 20D and the ring gear 35D of the fifth embodiment without changing the shape of the main body casing 2 side.

The present embodiment has been described above with reference to the embodiments, but the present invention is not limited to the above embodiments, and can be modified within a range not departing from the spirit thereof. For example, although the impact tool 1 is described as an example of the electric tool in the above embodiment, the present invention is also applicable to a power tool for driving a drill, a grinder, or the like, as long as the rotational force generated by the drive source is transmitted to the power transmission mechanism using the planetary gear reduction mechanism, and the same applies to a tool such as the driving of a tip tool. The electric power tool according to the above embodiment has the housing formed by the synthetic resin main body housing 2 and the metal hammer case 3, but the same applies to an electric power tool in which the housing is formed as a whole by the synthetic resin main body housing without using the hammer case 3.

Claims

1. An electric tool having a motor, a speed reducing mechanism for reducing the rotation of the motor, and a housing for housing the motor and the speed reducing mechanism,

the reduction mechanism comprises a planetary gear, a gear ring positioned outside the planetary gear, and a sun gear positioned inside the planetary gear and connected with the motor,

the electric tool is characterized in that,

an inner cover which is provided between the motor and the reduction mechanism so as not to rotate relative to the housing and is held by the housing, the inner cover supporting a bearing of the reduction mechanism,

the inner cover and the ring gear are supported by the inner peripheral surface of the ring gear so as to prevent relative rotation.

2. An electric tool having a motor, a speed reducing mechanism for reducing the rotation of the motor, and a housing for housing the motor and the speed reducing mechanism,

the electric tool is characterized in that,

an inner cover which is provided with a bearing for supporting the speed reducing mechanism and is held by the outer cover in a mode of not rotating relatively to the outer cover,

the internal cover is configured to be partially housed on the inner peripheral side of the ring gear so as to prevent relative rotation between the internal cover and the ring gear.

3. The power tool according to claim 2, wherein,

the inner cover is disposed between the motor and the reduction mechanism, and an outer peripheral surface of the inner cover is supported by an inner peripheral surface of the ring gear so as to prevent relative rotation between the inner cover and the ring gear.

4. The power tool according to any one of claim 1 to 3, wherein,

the gear ring is made of metal or synthetic resin, has a gear portion formed on the inner side, and has a cylindrical portion extending in the axial direction so as to be adjacent to the gear portion,

a part of the inner cover is accommodated inside the cylinder.

5. The power tool of claim 4, wherein the power tool comprises a power tool,

the inner cover has a concave-convex portion protruding or recessed in a radial direction, and the ring gear has a concave-convex portion having a convex-concave shape corresponding to the concave-convex portion, and the relative rotation of the ring gear and the inner cover is prevented by engagement of the concave-convex portion with the concave-convex portion.

6. The power tool of claim 5, wherein the power tool comprises,

the concave-convex portions are respectively arranged in plurality.

7. The power tool of claim 6, wherein the power tool comprises a power tool,

the rotation shaft of the motor and the rotation center of the reduction mechanism are coaxially arranged,

the inner cover fixes one of the motor bearings for supporting the rotary shaft and one of the gear bearings for supporting the reduction mechanism, and has a first cylindrical portion for holding an outer peripheral surface of the motor bearing and a second cylindrical portion for holding an outer peripheral surface of the gear bearing.

8. The power tool of claim 7, wherein the power tool comprises a power tool,

the housing includes a synthetic resin member which can be divided by a dividing surface including a rotation axis of the motor, the inner cover is sandwiched by the housing so as to intersect the dividing surface,

the inner cover and the outer cover are formed with rotation stopping parts in a manner of not rotating relatively.

9. The power tool of claim 7, wherein the power tool comprises a power tool,

based on the power transmission mechanism converting the output of the above-described reduction mechanism into the driving force of the front end tool,

the housing includes a cup-shaped metal shell for accommodating the power transmission mechanism,

the ring gear and the opening edge of the metal case have the same diameter and are arranged so as to be aligned with the opening edge in the axial direction.