CN210307665U

CN210307665U - Electric tool

Info

Publication number: CN210307665U
Application number: CN201790001087.1U
Authority: CN
Inventors: 西河智雅
Original assignee: Hitachi Koki Co Ltd
Current assignee: Koki Holdings Co Ltd
Priority date: 2016-09-30
Filing date: 2017-08-25
Publication date: 2020-04-14
Anticipated expiration: 2027-08-25
Also published as: JP6792627B2; DE212017000224U1; WO2018061556A1; JPWO2018061556A1

Abstract

The utility model provides an electric tool, it can not carry out the operation of fixed output portion and can carry out the installation of front end instrument easily. The electric tool is provided with a motor (4), a rotating shaft (41) which extends in the left-right direction and is rotated by the motor (4), an output part (61) which is rotated by transmitting the rotating force of the rotating shaft (41) and can be used for assembling and disassembling a saw blade (P), and a one-way overrunning clutch (8) which is positioned at the right end of the rotating shaft (41) in the left-right direction and can only transmit the positive rotation to limit the rotation of the rotating shaft (41).

Description

Electric tool

Technical Field

The utility model relates to an electric tool.

Background

Conventionally, the following electric power tools have been known: in order to prevent free rotation of an output shaft to which a tip tool (e.g., a saw blade) is attached when the tip tool is attached, a spindle lock that cuts off rotational force from a motor by an operation from the outside by an operator is provided in a rotational force transmission path through which the rotational force from the motor is transmitted (see patent document 1).

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2004-225642

SUMMERY OF THE UTILITY MODEL

Problem to be solved by utility model

However, in the electric power tool having the above-described configuration, it is necessary for the operator to rotate a coupling tool (e.g., a bolt) for fixing the tip tool to the output shaft while operating the spindle lock at the time of attaching or detaching the tip tool, which is troublesome.

Therefore, an object of the present invention is to provide an electric power tool in which a tip tool can be easily replaced without performing an operation of fixing an output portion.

Means for solving the problems

Provided is a power tool characterized in that: the tool includes a motor, a rotary shaft extending in a predetermined direction and rotated by the motor, an output portion rotated by transmitting a rotational force of the rotary shaft and to which a tool bit can be attached and detached, a speed reduction mechanism for reducing the speed of rotation of the rotary shaft and transmitting the reduced speed to the output portion, and a restricting member located at one end of the rotary shaft in the predetermined direction, the restricting member allowing rotation of the rotary shaft in one of forward and reverse directions and prohibiting rotation in the other direction.

According to the electric power tool configured as described above, the restricting member supports the rotary shaft that transmits the rotational force to the output portion so as to transmit the rotation only in one of the forward and reverse directions. Therefore, the rotation in one direction of the output unit is allowed, and the rotation in the other direction is restricted. This makes it possible to omit the operation of fixing the output portion and to easily replace the tip tool.

In the above configuration, it is preferable to provide a fixing mechanism for restricting the rotation of the output unit in both the forward and reverse directions.

According to this configuration, the restricting member supports the rotary shaft as a bearing while restricting rotation in the other direction of the rotary shaft. Thus, since the rotation support and the rotation restriction of the rotation shaft can be performed by a single member, a simple and low-cost configuration can be achieved without providing a new member.

Preferably, the motor includes a rotor that rotates integrally with the rotating shaft.

According to this configuration, by restricting the rotation of the rotating shaft before deceleration, the rotation of the output portion can be restricted by restricting the rotation at a position where the torque is relatively small, and the load applied to the restricting member can be suppressed, thereby achieving a long life.

The speed reduction mechanism is located on the output portion side with respect to the rotor in the predetermined direction, and the electric power tool further includes a gear housing that supports an end portion of the rotary shaft located on the output portion side with respect to the rotor in the predetermined direction and the speed reduction mechanism, and the gear housing preferably supports the end portion via the regulating member.

According to this configuration, since the end portion of the rotary shaft and the reduction mechanism are supported by one gear housing, the overall length of the electric power tool can be suppressed. Further, since the gear housing is formed so as to support the end portion of the rotating shaft by the regulating member, the gear housing can be manufactured to be suitable for the specification of the regulating member, and the assembly of the electric power tool becomes easy by using the gear housing suitable for the specification of the regulating member. The restricting member supports the rotary shaft as a bearing while restricting rotation of the rotary shaft in the other direction. Thus, the rotation support and the rotation restriction of the rotation shaft can be performed by a single member, and a simple and low-cost structure can be obtained without providing a new member.

The gear housing is preferably made of metal.

According to such a configuration, the strength of the position where the bearing member of the gear housing is disposed can be increased as compared with the case where the resin gear housing is used, and the electric power tool can be prevented from being damaged from the position where the regulating member is disposed.

In the above configuration, the restricting member is preferably a one-way clutch.

With this configuration, the rotation of the rotary shaft can be restricted with a relatively simple configuration.

In the above configuration, the motor is preferably a brushless motor.

According to such a configuration, the size of the electric power tool can be reduced and the weight thereof can be reduced by using a brushless motor that is smaller than a conventional commutator motor.

The motor is preferably provided with a housing for housing the motor, and a base for supporting the housing, the housing is provided with a handle that can be gripped, and the restriction member is preferably provided inside the housing at a position between the handle and the base.

In addition, it is preferable that the rotor is provided with a fan for cooling the motor, and the handle is positioned in the radial direction of the regulating member when the radial direction of the fan is defined as the radial direction.

Effect of the utility model

According to the electric tool of the present invention, the front end tool can be easily attached or detached without performing the operation of fixing the output portion.

Drawings

Fig. 1 is a sectional view showing an internal structure of a housing of an electric circular saw according to a first embodiment of the present invention.

Fig. 2 is a plan view showing an upper external view of the electric circular saw according to the first embodiment of the present invention, and shows an engagement state of the rotation shaft of the motor and the spindle lock in the plan view by a cross section.

Fig. 3 is a sectional view taken along line L-L of fig. 2, showing a state where rotation of the rotary shaft of the motor is permitted.

Fig. 4 is an enlarged cross-sectional view showing a gear portion of an electric circular saw according to a first embodiment of the present invention.

Fig. 5 is an enlarged cross-sectional view of the one-way clutch in the left side view of the electric circular saw according to the first embodiment of the present invention, and is a view showing a state in which the rotation shaft of the motor is allowed to rotate in the normal direction by the one-way clutch.

Fig. 6 is an enlarged cross-sectional view of the one-way clutch in a left side view of the electric circular saw according to the first embodiment of the present invention, and is a view showing a state in which the reverse rotation of the rotation shaft of the motor is restricted by the one-way clutch.

Fig. 7 is a sectional view taken along line L-L of fig. 2, showing a state in which a rotary shaft of a motor is fixed by a spindle lock.

Fig. 8 is a sectional view showing an internal structure of a housing of an electric circular saw according to a second embodiment of the present invention.

Fig. 9 is a sectional view taken along line a-a of fig. 8, showing a structure of the dog clutch.

Fig. 10 is a rear view showing a rear appearance of a table-type circular saw according to a third embodiment of the present invention, and shows an internal structure of a housing in a rear view in cross section.

Fig. 11 is a cross-sectional view showing an internal structure of a disc grinder according to a fourth embodiment of the present invention.

Detailed Description

[ first embodiment ]

Hereinafter, an electric circular saw 1 according to a first embodiment of the present invention will be described with reference to fig. 1 to 7. First, the structure of the electric circular saw 1 will be described with reference to fig. 1 to 5. In the following description of the electric circular saw 1, "up" shown in fig. 1 is defined as an upward direction, "down" as a downward direction, "right" as a right direction, and "left" as a left direction. The depth of the paper surface is defined as the rear direction, and the front of the paper surface is defined as the front direction.

The electric circular saw 1 is an electric tool for cutting wood or the like (material to be cut). As shown in fig. 1 and 2, the electric circular saw 1 includes a housing 2, a handle 3, a motor 4, a gear portion 5, a blade mounting portion 6, a spindle lock 7, a one-way overrunning clutch 8, and a base 9. Fig. 1 is a sectional view showing an internal structure of a housing 2 of an electric circular saw 1 according to a first embodiment of the present invention. Fig. 2 is a plan view showing an appearance of the electric circular saw 1 according to the first embodiment of the present invention in plan view, and shows an engagement mode of the rotation shaft of the motor 4 and the spindle lock 7 in plan view by a cross section.

As shown in fig. 1, the housing 2 includes a motor housing 21, a gear housing 22, and a cover 23. A base 9 that abuts against a material to be cut (wood or the like) during cutting operation is provided at a lower right portion of the housing 2. The base 9 indicated by a broken line in fig. 1 indicates that the base 9 can be tilted about an axis extending in the front-rear direction as a tilt center. The base 9 is an example of the "base" in the present invention. The housing 2 is an example of the "housing" in the present invention.

As shown in fig. 1 and 2, the motor housing 21 has a substantially cylindrical shape extending in the left-right direction, and houses the motor 4 and the spindle lock 7 therein.

As shown in fig. 1, the gear housing 22 extends rightward from the right end of the motor housing 21, and houses the right end portion of the motor 4, the gear portion 5, the left portion of the blade mounting portion 6, and the one-way clutch 8. The gear housing 22 is made of metal (e.g., aluminum). The gear housing 22 is an example of the "gear housing" in the present invention. The right end of the motor 4 is an example of the "end" in the present invention.

The cover 23 is made of resin (e.g., plastic), extends rightward from a lower portion of the gear housing 22, and houses a right portion of the blade mounting portion 6.

The handle 3 is a portion that is gripped by an operator when using the electric circular saw 1, and extends in the front-rear direction above the housing 2. A wrench, not shown, for driving the motor 4 is provided on the handle 3. The handle 3 is an example of the "handle" in the present invention.

The motor 4 is a DC brushless motor, and includes a rotating shaft 41 and a rotor 42. The motor 4 is an example of the "motor" and the "brushless motor" in the present invention. The rotary shaft 41 is an example of the "rotary shaft" in the present invention.

As shown in fig. 1, the rotary shaft 41 extends in the left-right direction, and is supported by the housing 2 so as to be rotatable about the shaft center a as a rotation shaft center via the first bearing 46 and the one-way clutch 8. A pinion gear 43 is provided to the right of the rotary shaft 41. The rotary shaft 41 and the pinion 43 rotate integrally. A rotation-restricted portion 44 is provided on the left portion of the rotating shaft 41. A fan 45 for cooling the motor 4 is fixed to the left of the rotation restricted portion 44 so as to rotate coaxially with the rotary shaft 41. The one-way clutch 8 is circular and is disposed substantially parallel to the circular fan 45. That is, the radial direction of the one-way clutch 8 is parallel to and in the same direction as the radial direction of the fan 45. Here, the axis a shown in the drawing is an imaginary rotation axis extending in the left-right direction through the center of the rotation shaft 41 in the right view. The left-right direction is an example of the "predetermined direction" in the present invention. The fan 45 is an example of the "fan" in the present invention.

The rotation-restricted portion 44 extends in the left-right direction and the up-down direction, and is provided between the one-way clutch 8 and the fan 45 in the left-right direction. As shown in fig. 3, the rotation-restricted portion 44 has a first engagement surface 44A and a second engagement surface 44B. Fig. 3 is a sectional view taken along line L-L of fig. 2, showing a state in which the rotation shaft 41 of the motor 4 is allowed to rotate.

The first engagement surface 44A is a flat surface substantially orthogonal to the vertical direction. The second engagement surface 44B is a flat surface substantially orthogonal to the vertical direction, and is formed substantially parallel to the first engagement surface 44A. The first engagement surface 44A is located above the second engagement surface 44B.

The rotor 42 is formed in a cylindrical shape extending in the left-right direction. The rotor 42 is coaxially fixed to the rotary shaft 41, and rotates integrally with the rotary shaft 41 with the axis a as a rotation axis. The rotor 42 is an example of the "rotor" in the present invention.

As shown in fig. 1, the gear portion 5 is located in the gear housing 22, is provided on a rotational force transmission path from the motor 4 to the blade mounting portion 6, and is capable of transmitting the rotational force to the blade mounting portion 6 while decelerating the rotation of the rotational shaft 41. The gear portion 5 is located on the output side with respect to the rotor. As shown in fig. 4, the gear portion 5 includes a first gear 51, a second gear 52, a third gear 53, an intermediate shaft 54, a second bearing 55, and a third bearing 56. Fig. 4 is an enlarged cross-sectional view showing the gear portion 5 of the electric circular saw 1 according to the first embodiment of the present invention. In fig. 4, the gear housing 22 is hatched with an oblique line from the upper right to the lower left, and the cover 23 is hatched with an oblique line from the upper left to the lower right. The gear portion 5 is an example of the "reduction mechanism" in the present invention.

The intermediate shaft 54 extends in the left-right direction, and is supported by the gear housing 22 and the cover 23 via a second bearing 55 and a third bearing 56 so that the shaft center B can rotate as a rotation shaft center. Here, the axial center B shown in the drawing is an imaginary rotational axial center passing through the center of the intermediate shaft 54 in the right-view and extending in the left-right direction. The axis B is substantially parallel to the axis A.

The first gear 51 meshes with the pinion 43 of the motor 4. The first gear 51 is fixed to the intermediate shaft 54 by press fitting. The first gear 51 rotates integrally with the intermediate shaft 54 about the shaft center B as a rotation shaft center. The first gear 51 has an outer diameter larger than that of the pinion 43.

The second gear 52 is positioned to the right of the first gear 51, and is fixed to an intermediate shaft 54 by press fitting. The second gear 52 rotates integrally with the intermediate shaft 54 and the first gear 51 about the axial center B as a rotation axial center.

The third gear 53 is located below the second gear 52. The third gear 53 has an outer diameter larger than that of the second gear 52.

As shown in fig. 1, the blade mounting portion 6 extends rightward from a lower portion of the gear housing 22 and is configured to be attachable to and detachable from the blade P. The blade mounting portion 6 includes an output portion 61, a socket 62, a blade fixing cover 63, and a bolt 64.

As shown in fig. 4, the output portion 61 has a substantially cylindrical shape extending in the left-right direction, and a bolt 64 can be coupled to a substantially center in the radial direction. The output portion 61 is supported by the gear housing 22 and the cover 23 via a fourth bearing 65 and a fifth bearing 65 so as to be rotatable about the axis C as a rotation axis. The third gear 53 of the fixing gear portion 5 is press-fitted into the right portion of the output portion 61. The output portion 61 rotates integrally with the third gear 53 with the axis C as a rotation axis. The output unit 61 is an example of the "output unit" in the present invention.

The socket 62 shown in fig. 1 is made of metal, and fixes the output portion 61 by press fitting or the like. The socket 62 includes a body portion 62A and a protruding portion 62B.

The body section 62A is formed in a cylindrical shape extending in the left-right direction.

The protruding portion 62B protrudes from the right end of the body portion 62A radially outward of the body portion 62A. The protruding portion 62B includes an abutment surface 62C that is in a right loop shape and is orthogonal to the left-right direction. The inner diameter of the contact surface 62C is substantially the same as the inner diameter of the annularly formed saw blade P.

The blade fixing cover 63 is made of resin and includes an annular portion 63A and a fixing portion 63B.

The annular portion 63A is formed in a right-view ring shape.

The fixing portion 63B protrudes leftward and outward in the radial direction from the radially outer end of the annular portion 63A. The fixing portion 63B includes a contact surface 63C having a right-view ring shape and orthogonal to the left-right direction. The inner diameter of the contact surface 63C is substantially the same as the inner diameter of the ring-shaped saw blade P. As shown in fig. 1, the abutment surface 63C is positioned to face the abutment surface 62C in the left-right direction when the bolt 64 is fastened.

As shown in fig. 1, in a state where the bolt 64 is coupled to the output section 61, the bolt 64 extends in the left-right direction. The bolt 64 includes a right hexagonal head 64A to allow an operator to connect the bolt from the outside.

The spindle lock 7 shown in fig. 2 and 3 is a member for restricting the rotation of the rotary shaft 41 when the saw blade P is attached to and detached from the blade mounting portion 6 during non-operation. As shown in fig. 3, the spindle lock 7 includes an arm portion 71, a pressed portion 72, a regulating portion 73, and a forced portion 74.

The arm portion 71 is formed in a thin plate shape extending in the front-rear direction, and a front portion thereof protrudes outward of the housing 2.

As shown in fig. 2, the pressed portion 72 is located at the tip of the arm portion 71. The pressed portion 72 includes a pressed surface 72A extending rightward from the front end of the arm portion 71 and operable by the operator from the outside.

As shown in fig. 3, the restricting portion 73 extends in the front-rear direction and includes a first restricting surface 73A and a second restricting surface 73B.

The first limiting surface 73A is a flat surface substantially orthogonal to the vertical direction. The second limiting surface 73B is a flat surface substantially orthogonal to the vertical direction, and is formed substantially parallel to the first limiting surface 73A. The first restriction surface 73A is located above the second restriction surface 73B. The distance between the first limiting surface 73A and the second limiting surface 73B and the distance between the first engaging surface 44A and the second engaging surface 44B of the rotation-regulated portion 44 of the motor 4 are substantially the same.

The urged portion 74 extends in the front-rear direction, and abuts against the spring 2A at its tip.

The arm portion 71, the pressed portion 72, the regulating portion 73, and the urged portion 74 are integrally formed, and can be integrally moved rearward by pressing the pressed portion 72 rearward by the operator.

The one-way clutch 8 is a member that allows (allows transmission of) normal rotation (clockwise rotation in fig. 5, the same applies to the first embodiment below) of the rotary shaft 41 and the pinion 43 that rotates integrally with the rotary shaft 41, and restricts reverse rotation (counterclockwise rotation in fig. 5, the same applies to the first embodiment below). The one-way clutch 8 is provided between the inner wall of the gear housing 22 and the rotary shaft 41 of the motor 4. The one-way overrunning clutch 8 is arranged between the handle 3 and the base 9 in the up-down direction, and the handle 3 is positioned in the radius direction of the one-way overrunning clutch 8. In other words, the one-way clutch 8 is located substantially on the same plane as the handle 3 in an imaginary plane extending vertically and longitudinally. The one-way overrunning clutch 8 is located at the right end of the rotating shaft 41. The one-way clutch 8 includes a cylindrical portion 81, a plurality of rollers 82, and a plurality of springs 83. Fig. 5 is an enlarged cross-sectional view of the one-way clutch 8 in the rear view of the electric circular saw 1 according to the first embodiment of the present invention, and is a view showing a state in which the one-way clutch 8 allows the rotation shaft 41 of the motor 4 to rotate in the normal direction. In fig. 5, the rotary shaft 41 of the motor 4 is hatched with an oblique line from the upper right to the lower left, and the gear housing 22 is hatched with an oblique line from the upper left to the lower right. The one-way overrunning clutch 8 is an example of the "restricting member", the "bearing member", and the "one-way overrunning clutch" of the present invention. The right end of the rotary shaft 41 is an example of "one end of the rotary shaft" in the present invention. The forward rotation is an example of "rotation in one of the forward and reverse directions" in the present invention.

As shown in fig. 1, the cylindrical portion 81 has a cylindrical shape extending in the left-right direction, and is fixed to the inner wall of the gear housing 22 by press fitting. As shown in fig. 5, a plurality of receiving grooves 81a are formed in the inner circumferential surface of the cylindrical portion 81. The housing groove 81a is a groove formed by recessing from the inner circumferential surface of the cylindrical portion 81 to the outer side in the radial direction of the cylindrical portion 81, and extends in the left-right direction. A set of rollers 82 and a spring 83 are accommodated in the plurality of accommodating grooves 81a, respectively.

The roller 82 is a needle-like needle roller extending in the left-right direction, and is housed in the housing groove 81a in a state of being capable of rotating about its axis and abutting against the rotary shaft 41. The roller 82 is immovable in the left-right direction inside the housing groove 81a and is movable by a predetermined amount in the circumferential direction of the rotary shaft 41.

The depth of the housing groove 81a increases from the upstream side to the downstream side of the housing groove 81a in the normal rotation direction of the rotary shaft 41, and the depth of the upstream side edge is smaller than the diameter of the roller 82 and the depth of the downstream side edge is larger than the diameter of the roller 82. Further, a spring 83 is provided as an urging member between the roller 82 accommodated in the accommodating groove 81a and the downstream edge of the accommodating groove 81a, and the roller 82 is urged from the downstream edge to the upstream edge.

Next, the operation of the electric circular saw 1 in the cutting operation of the material to be cut (wood or the like) using the electric circular saw 1 according to the first embodiment will be described with reference to fig. 3 to 7.

When performing the cutting operation, the operator holds the handle 3 and places the electric circular saw 1 in a state where the base 9 is in contact with the material to be cut. In this state, when a pulling operation is performed on a wrench, not shown, of the handle 3, electric power is supplied from a power supply, not shown, to the motor 4, and the motor 4 starts to be driven. When the motor 4 starts driving, the rotary shaft 41, the rotor 42, and the pinion 43 start normal rotation with the axis a as the rotation axis.

As shown in fig. 5, when the rotary shaft 41 starts to rotate in the normal direction, the rollers 82 that abut against the outer peripheral surface of the rotary shaft 41 rotate about their respective axial centers inside the respective receiving grooves 81a that receive the rollers, and move from the upstream edge portion to the downstream edge portion in the normal rotation direction of the rotary shaft 41 against the urging force of the springs 83. When the roller 82 is located at the downstream edge of the deepest receiving groove 81a, the contact surface pressure between the outer peripheral surface of the rotary shaft 41 and the roller 82 is reduced. The frictional force between the rollers 82 and the outer peripheral surface of the rotary shaft 41 due to the contact surface pressure in this state is not so strong as to prevent the rotary shaft 41 from rotating normally with respect to the cylindrical portion 81, and the rotary shaft 41 can continue to rotate normally in this state. That is, the one-way clutch 8 allows normal rotation of the rotary shaft 41, the rotor 42, and the pinion 43.

In this state, the first gear 51 meshing with the pinion 43 starts to rotate reversely with the shaft center B as the rotation shaft center. Thereby, the first gear 51, the second gear 52, and the intermediate shaft 54 integrally reverse the shaft center B as the rotation shaft center. Here, as shown in fig. 4, since the outer diameter of the first gear 51 is configured to be larger than the outer diameter of the pinion gear 43, the rotation speed of the first gear 51, the second gear 52, and the intermediate shaft 54 is smaller than the rotation speed of the pinion gear 43.

In this state, the third gear 53 meshing with the second gear 52 starts normal rotation with the shaft center C as the rotation shaft center. Thus, the third gear 53 and the output portion 61 rotate normally integrally about the axial center C as the rotation axial center. Here, since the outer diameter of the third gear 53 is configured to be larger than the outer diameter of the second gear 52, the rotation speed of the third gear 53 and the output portion 61 is smaller than the rotation speed of the second gear 52. That is, the rotation of the rotary shaft 41 is decelerated twice and transmitted to the output unit. This enables a high torque to be generated in the output portion 61.

In this state, the saw blade P fixed to the blade mounting portion 6 rotates with the rotation of the output portion 61, and cuts the material to be cut.

Further, with reference to fig. 5 to 7, the operation of attaching (replacing) the saw blade P of the electric circular saw 1 by the operator will be described.

First, the operation of detaching the saw blade P of the electric circular saw 1 by an operator will be described.

When performing the removal operation, the operator presses the pressed surface 72A of the spindle lock 7 rearward. Thereby, the spindle lock 7 moves rearward.

As shown in fig. 7, the first engagement surface 44A of the rotation-restricted portion 44 of the rotating shaft 41 and the first restriction surface 73A of the restriction portion 73 of the spindle lock 7 face each other at substantially the same position in the vertical direction as the spindle lock 7 moves rearward. Thereby, the rotation of the rotating shaft 41 is restricted.

In this state, the operator rotates in the direction (forward rotation direction) of loosening the connection of the bolt 64 using a tool (wrench or the like), not shown, while pressing the pressed surface 72A of the spindle lock 7 rearward. In this state, the output portion 61 rotates normally, but the rotation of the rotary shaft 41 is restricted, so that the rotation of the first gear 51, the second gear 52, and the intermediate shaft 54 is restricted, and the rotation of the output portion 61 is restricted by restricting the rotation of the third gear 53 that rotates integrally with the output portion 61. Thus, the saw blade P can be detached from the blade mounting portion 6 by loosening the connection of the bolt 64 with a tool (wrench or the like) not shown. The main shaft locking member 7 and the rotation-restricted portion 44 are examples of the "fixing mechanism" in the present invention.

Next, the operation of attaching the saw blade P of the electric circular saw 1 by the operator will be described.

When performing the mounting operation, the operator rotates in a direction (reverse direction) in which the bolt 64 is tightened, using a tool (wrench or the like) not shown. In this state, the rotation shaft 41 starts to rotate in reverse as the output unit 61 rotates in reverse.

As shown in fig. 6, when the rotation shaft 41 starts to rotate in the reverse direction, the rollers 82 start to move from the downstream edge to the upstream edge in the normal rotation direction of the rotation shaft 41 against the biasing force of the springs 83 while rotating around their axes in the respective storage grooves 81a that store the rollers. When the roller 82 is located at the upstream edge portion where the depth of the receiving groove 81a is the shallowest, the contact surface pressure between the outer circumferential surface of the rotary shaft 41 and the roller 82 becomes the largest. In this state, the frictional force between each roller 82 and the outer peripheral surface of the rotating shaft 41 due to the contact surface pressure is maximized, and the rotating shaft cannot be reversed with respect to the cylindrical portion 81. That is, the one-way clutch 8 restricts the reverse rotation of the rotary shaft 41, the rotor 42, and the pinion 43. In this state, since the reverse rotation of the rotary shaft 41 is restricted, the reverse rotation of the output portion 61 is restricted by restricting the normal rotation of the first gear 51, the second gear 52, and the intermediate shaft 54 and restricting the reverse rotation of the third gear 53 that rotates integrally with the output portion 61. This allows the operator to easily attach the saw blade P without performing an operation of fixing the output portion 61. Fig. 6 is an enlarged cross-sectional view of the one-way clutch 8 in the rear view of the electric circular saw 1 according to the first embodiment of the present invention, and is a view showing a state in which the reverse rotation of the rotary shaft 41 of the motor 4 is restricted by the one-way clutch 8. In fig. 6, the rotary shaft 41 of the motor 4 is hatched with an oblique line from the upper right to the lower left, and the gear housing 22 is hatched with an oblique line from the upper left to the lower right.

[ second embodiment ]

An electric circular saw 201 according to a second embodiment of the present invention will be described with reference to fig. 8 and 9. The same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. Fig. 8 is a sectional view showing an internal structure of a housing 2 of an electric circular saw 201 according to a second embodiment of the present invention. Fig. 9 is a sectional view taken along line a-a of fig. 8, showing a structure of the dog clutch.

First, the structure of the electric circular saw 201 will be described. In the following description of the electric circular saw 201, "up" shown in fig. 8 is defined as an upward direction, "down" as a downward direction, "right" as a right direction, and "left" as a left direction. The depth of the paper surface is defined as the rear direction, and the front of the paper surface is defined as the front direction.

As shown in fig. 8, in the electric circular saw 201 according to the second embodiment, a bearing 208 that allows rotation of the rotating shaft 41 of the motor 4 in both forward and reverse directions is provided in place of the one-way clutch 8, and a dog clutch 210 is provided at the left portion inside the motor housing 21.

The dog clutch 210 shown in fig. 8 and 9 is positioned at the left end of the rotary shaft 41, and is a member that allows normal rotation and restricts reverse rotation of the rotary shaft 41 and the pinion 43 that rotates integrally with the rotary shaft 41. The dog clutch 210 includes a ratchet 210A, a rotation restricting member 210B, and a spring 210C.

As shown in fig. 9, the ratchet 210A is formed in a substantially ring shape as viewed from the right. The rotating shaft 41 of the motor 4 is press-fitted and fixed to the substantially center of the ratchet 210A in the radial direction. The ratchet 210A and the rotating shaft 41 of the motor 4 can rotate integrally with the shaft center a as a rotation shaft center. The ratchet 210A includes a plurality of rotation-restricted surfaces 210D at predetermined intervals in the circumferential direction.

As shown in fig. 8 and 9, the rotation restricting member 210B is a member extending in the vertical direction. The rotation restricting member 210B abuts on the ratchet 210A below the rotating shaft 41. The rotation restricting member 210B includes a rotation restricting surface 210E orthogonal to the front-rear direction.

As shown in fig. 9, the lower end of the spring 210C abuts against the motor housing 21, the upper end abuts against the lower end of the rotation restricting member 210B, and the rotation restricting member 210B is urged upward with respect to the motor housing 21.

Next, the operation of the electric circular saw 201 in the cutting operation of the material to be cut (wood or the like) using the electric circular saw 201 according to the second embodiment will be described.

When performing the cutting operation, the operator holds the handle 3 and places the electric circular saw 201 in a state where the base 9 is in contact with the material to be cut. In this state, when a wrench, not shown, of the handle 3 is pulled, electric power is supplied from a power supply, not shown, to the motor 4, and the motor 4 starts to be driven. When the motor 4 starts driving, the rotary shaft 41, the rotor 42, and the pinion 43 start normal rotation with the axis a as the rotation axis. In the second embodiment, the counterclockwise rotation of the rotary shaft 41 in fig. 9 is defined as the normal rotation, and the clockwise rotation is defined as the reverse rotation.

When the rotation shaft 41 starts to rotate forward, the ratchet 210A starts to rotate forward integrally with the rotation shaft 41. As the ratchet gear 210A rotates forward, friction is generated at the contact point between the ratchet gear 210A of the dog clutch 210 and the rotation restriction member 210B. In this state, the rotation restricting member 210B moves downward against the urging force of the spring 210C, and the contact surface pressure at the contact point between the ratchet 210A and the rotation restricting member 210B is reduced. Accordingly, since the frictional force acting on the contact point between the ratchet 210A and the rotation restricting member 210B is small, the ratchet 210A can continue the normal rotation integrally with the rotary shaft 41. That is, the dog clutch 210 allows the rotation shaft 41, the rotor 42, and the pinion 43 to rotate in the normal direction.

In this state, the first gear 51 meshing with the pinion 43 starts to rotate reversely with the shaft center B as the rotation shaft center. Thereby, the first gear 51, the second gear 52, and the intermediate shaft 54 integrally reverse the shaft center B as the rotation shaft center. Here, as shown in fig. 4, since the outer diameter of the first gear 51 is larger than the outer diameter of the pinion gear 43, the rotation speed of the first gear 51, the second gear 52, and the intermediate shaft 54 is smaller than the rotation speed of the pinion gear 43.

In this state, the third gear 53 meshing with the second gear 52 starts normal rotation with the shaft center C as the rotation shaft center. Thus, the first gear 53 and the output portion 61 rotate normally integrally about the axial center C as the rotation axial center. Here, since the outer diameter of the third gear 53 is configured to be larger than the outer diameter of the third gear 52, the rotation speed of the third gear 53 and the output portion 61 is smaller than the rotation speed of the second gear 52. This can generate high torque in the output portion 61.

Referring to fig. 8 and 9, the operation of attaching the blade P of the electric circular saw 201 by the operator will be described. Since the operation of detaching the saw blade P is the same as that of the electric circular saw 1, the description thereof is omitted.

When the bolt 64 is to be attached, the operator rotates the bolt in a direction (reverse direction) in which the bolt is to be tightened (reverse direction) using a tool (wrench, etc.), not shown. In this state, the rotation shaft 41 starts to rotate in reverse as the output unit 61 rotates in reverse.

When the rotation shaft 41 starts to rotate reversely, the ratchet 210A starts to rotate reversely integrally with the rotation shaft 41. As the ratchet 210A rotates in the reverse direction, the rotation-restricted surface 210D of the ratchet 210A and the rotation-restricting surface 210E of the rotation-restricting member 210B face each other at substantially the same position in the front-rear direction. In this state, since the reverse rotation of the ratchet 210A is restricted, the reverse rotation of the rotary shaft 41 is restricted. That is, the dog clutch 210 regulates the reverse rotation of the rotary shaft 41, the rotor 42, and the pinion 43. In this state, since the reverse rotation of the rotary shaft 41 is restricted, the normal rotation of the first gear 51, the second gear 52, and the intermediate shaft 54 is restricted, and the reverse rotation of the output portion 61 is restricted by restricting the reverse rotation of the third gear 53 that rotates integrally with the output portion 61. This allows the operator to easily attach the saw blade P without performing an operation of fixing the output portion 61.

[ third embodiment ]

A table-type circular saw 301 according to a third embodiment of the present invention will be described with reference to fig. 10. The same components as those in the first and second embodiments are denoted by the same reference numerals, and the description thereof is omitted. Fig. 10 is a rear view showing a rear appearance of a table-type circular saw according to a third embodiment of the present invention, and an internal structure of a housing in the rear view is shown in a cross-sectional view.

First, the structure of the circular table saw 301 will be described. In the following description of the table-top circular saw 301, "up" shown in fig. 10 is defined as an up direction, "down" as a down direction, "right" as a right direction, and "left" as a left direction. The depth of the paper surface is defined as the forward direction, and the near side of the paper surface is defined as the backward direction.

The table-type circular saw 301 is an electric tool for cutting wood or the like (material to be cut) on a table. As shown in fig. 10, the table-type circular saw 301 includes a housing 302, a handle 303 held by an operator during operation, a motor 304, a gear portion 305, a blade mounting portion 306 to which a blade Q is detachably attached, a spindle lock 307, a one-way clutch 308, a base portion 309 on which a material to be cut (wood or the like) is placed during cutting operation, and a pulley mechanism 310 that transmits a rotational force of the motor 304 to the gear portion 305.

The housing 302 includes a motor housing 302A that houses a motor 304 therein, a gear housing 302B, and a cover 302C.

The gear housing 302B extends downward from the lower end of the right portion of the motor housing 302A, and houses a gear portion 305, the right portion of the blade mounting portion 306, and a one-way clutch 308. The gear housing 302B is made of metal (e.g., aluminum).

The cover 302C is made of resin (e.g., plastic), extends leftward from a lower portion of the gear housing 302B, and receives a right portion of the blade mounting portion 306.

The handle 303 is a portion that is held by the operator when the desk-top circular saw 301 is used, and extends in the front-rear direction above the housing 302. A wrench, not shown, for driving the motor 304 is provided on the handle 303.

The gear portion 305 is located in the gear housing 302B, is provided on a rotational force transmission path from the motor 304 to the blade mounting portion 306, and is capable of transmitting the rotational force of the rotational shaft 304A to the blade mounting portion 306 while decelerating the rotation. The gear portion 305 includes a shaft 305A to which the rotational force of the motor 304 can be transmitted via the pulley mechanism 310, and a rotation-restricted gear 305B.

The shaft 305A extends in the left-right direction, and is supported by the housing 302 so as to be rotatable about an axial center substantially parallel to the left-right direction via the one-way clutch 308.

The rotation-restricted gear 305B is provided with a rotation-restricted hole 305a into which the spindle lock 307 can be inserted.

The blade mounting portion 306 has an output portion 306A extending in the left-right direction and to which a bolt 306B can be coupled.

The spindle lock 307 extends in the left-right direction, is positioned to the right of the rotation-restricted gear 305B of the gear portion 305, and can be inserted into the rotation-restricted hole 305a by an operation from the outside by an operator.

The one-way clutch 308 is a member that is located at the left end of the shaft 305A and restricts reverse rotation (rotation in the counterclockwise direction of the rotating shaft of the motor 4 in the left view, which is the same in the third embodiment) while allowing forward rotation of the shaft 305A (rotation in the clockwise direction of the rotating shaft 41 of the motor 4 in the left view, which is the same in the third embodiment below).

Next, the operation of the table circular saw 301 in the cutting operation of the material to be cut (wood or the like) using the table circular saw 301 according to the third embodiment will be described with reference to fig. 10.

When performing a cutting operation, the operator holds the handle 303 and places a material to be cut on the base 309. In this state, when a wrench, not shown, of the handle 303 is pulled, electric power is supplied from a power supply, not shown, to the motor 304, and the motor 304 starts to be driven. When the motor 304 starts driving, the rotary shaft 304A starts rotating forward.

In this state, the shaft 305A of the gear portion 305 receives the rotational force from the motor 304 via the pulley mechanism 310 and performs the normal rotation. Here, since the one-way clutch 308 permits the forward rotation of the shaft 305A, the shaft 305A can continue the forward rotation.

In this state, the output portion 306A rotates forward in accordance with the forward rotation of the gear portion 305, and the blade Q fixed to the blade mounting portion 306 rotates forward, thereby cutting the material to be cut.

The operation of attaching and detaching (replacing) the saw blade Q of the table-type circular saw 301 by the operator will be described.

When performing the detaching operation, the operator rotates in a direction (reverse direction) in which the bolt 306B is loosened using a tool (wrench or the like) not shown. In this state, the shaft 305A starts to rotate reversely as the output unit 306A rotates reversely.

In this state, the reverse rotation of the shaft 305A is restricted by the one-way clutch 308, and therefore the reverse rotation of the output portion 306A is restricted. This allows the operator to easily remove the saw blade Q without performing an operation of fixing the output portion 306A.

Next, the operation of attaching the saw blade Q of the table-type circular saw 301 by the operator will be described.

When performing the detaching operation, the operator presses the spindle lock 307 to the left. Thereby, the spindle lock 307 moves leftward.

In this state, the rotation of the rotation-restricted gear 305B is restricted as the spindle lock 307 is inserted into the rotation-restricted hole 305a of the rotation-restricted gear 305B. This restricts the transmission of the rotational force to the output portion 306A, and the operator can tighten the bolt 306B with a tool (wrench or the like), not shown, and can attach the saw blade Q to the blade attachment portion 306.

[ fourth embodiment ]

A disc grinder 401 according to a fourth embodiment of the present invention will be described with reference to fig. 11. The same components as those in the first, second, and third embodiments are denoted by the same reference numerals, and the description thereof is omitted. Fig. 11 is a cross-sectional view showing an internal structure of a disc grinder according to a fourth embodiment of the present invention.

First, the structure of the disc grinder 401 will be described. In the following description of the disc grinder 401, "up" shown in fig. 11 is defined as an up direction, "down" as a down direction, "front" as a front direction, and "back" as a back direction. The depth of the paper surface is defined as the right direction, and the near side of the paper surface is defined as the left direction.

The disc grinder 401 is an electric tool for cutting and grinding a metal steel material or the like (workpiece). As shown in fig. 11, the disc grinder 401 includes a housing 402, a motor 403, a bevel gear 404, a blade attachment portion 405 to which a blade R can be attached and detached, a spindle lock 406, and a one-way clutch 8.

The housing 402 includes a motor housing 402A that houses a motor 403 therein, a gear housing 402B, and a cover 402C. A switch, not shown, for driving the motor 403 is provided in the housing 402.

The gear housing 402B extends forward from the front of the motor housing 402A, and houses the bevel gear 404, the upper portion of the blade attachment portion 405, and the one-way clutch 8. The gear housing 402B is made of metal.

The cover 402C is made of metal, extends downward from the lower portion of the gear housing 402B, and houses the lower portion of the blade mounting portion 405.

Motor 403 includes rotating shaft 403A and rotor 403B.

The rotary shaft 403A extends in the left-right direction, and is supported by the housing 402 so as to be rotatable about the shaft center D as a rotary shaft center via the bearing 403 and the one-way clutch 8. A pinion gear 403C is provided to the right of the rotary shaft 403A. The rotary shaft 403A and the pinion gear 403C rotate integrally. A fan 403D that rotates coaxially with the rotary shaft 41 is fixed between the one-way clutch 8 and the rotor 403B in the front-rear direction. Here, the axis D shown in the drawing is an imaginary rotation axis extending in the left-right direction through the front center of the rotation shaft 403A.

A bevel gear 404 is located within the gear housing 402B and meshes with the pinion gear 403C. The bevel gear 404 can rotate about an axis substantially parallel to the vertical direction.

The blade mounting portion 405 extends downward from the lower portion of the gear housing 402B, and is configured to detachably mount a blade R (grinding blade). The blade attachment portion 405 includes an output portion 405A, a first flange 405B, a second flange 405C, a bearing 405D, and a bearing 405E.

As shown in fig. 11, the output portion 405A has a substantially cylindrical shape extending in the vertical direction. The output portion 405A is rotatably supported by the gear housing 402B and the cover 402C via a bearing 405D and a bearing 405E, with an axis orthogonal to the axis D and parallel to the vertical direction. The conical gear 404 is fixed to the output portion 405A by press fitting. The output portion 405A and the bevel gear 404 can rotate integrally around an axis perpendicular to the axis D and parallel to the vertical direction.

The spindle lock 406 is configured to restrict rotation of the bevel gear 404.

Here, the operation of the disc grinder 401 in cutting the workpiece (such as a steel material) using the disc grinder 401 according to the fourth embodiment will be described with reference to fig. 11.

When performing the cutting operation, the operator holds the housing 402 and presses the saw blade R against the workpiece. In this state, when a slide switch, not shown, disposed on a side surface of the housing 402 is operated, electric power is supplied from an external commercial power supply to the motor 4 through the power supply line, and the motor 4 starts to be driven. When the motor 403 starts to be driven, the rotation shaft 403A, the rotor 403B, and the pinion gear 403C start to rotate in the normal direction about the shaft center D as the rotation shaft center. In this state, the one-way clutch 8 allows the rotation shaft 403A to rotate in the normal direction, and therefore the rotation shaft 403A can continue to rotate in the normal direction. In the fourth embodiment, the clockwise rotation of the motor 403 in the rear view and the clockwise rotation of the output unit 405A in the plan view are defined as the normal rotation. The counterclockwise rotation of the motor 403 in the rear view and the counterclockwise rotation of the output unit 405A in the plan view are defined as the reverse rotation.

In this state, the bevel gear 404 meshing with the pinion gear 403C rotates integrally with the output portion 405A about an axial center substantially parallel to the vertical direction. The saw blade R fixed to the blade mounting portion 405 rotates with the rotation of the output portion 405A, and cuts and grinds the workpiece.

Further, the operation of attaching and detaching (replacing) the saw blade R of the disc grinder 401 by the operator will be described.

First, the operation of detaching the saw blade of the disc grinder 401 by the operator will be described.

When the removal operation is performed, the operator presses the spindle lock 406 downward. Thereby, the spindle lock 406 moves downward and engages with the bevel gear 404, thereby restricting the rotation of the bevel gear 404.

In this state, the operator rotates in a direction (forward rotation direction) to loosen the connection of the second flange 405C. In this state, the output unit 405A intends to rotate normally, but the rotation of the output unit 405A is restricted because the rotation of the bevel gear 404 is restricted. Thus, the operator can detach the saw blade R from the blade attachment portion 405 by loosening the connection of the second flange 405C using a special tool not shown.

Next, the operation of attaching the saw blade R of the disc grinder 401 by the operator will be described.

When performing the mounting work, the operator rotates in a direction (reverse direction) to tighten the second flange 405C. In this state, the rotation shaft 403A of the motor 403 starts to rotate in reverse as the output unit 405A rotates in reverse.

In this state, since the reverse rotation of the rotary shaft 403A of the motor 403 is restricted by the one-way clutch 8, the reverse rotation of the output part 405A is restricted by restricting the reverse rotation of the bevel gear 404 that rotates integrally with the output part 405A. This allows the operator to easily attach the saw blade R without performing an operation of fixing the output portion 405A.

As described above, the electric circular saw 1 according to the first embodiment of the present invention includes the motor 4, the rotating shaft 41 extending in the left-right direction and rotated by the motor 4, the output portion 61 rotated by transmitting the rotational force of the rotating shaft 41 and capable of attaching and detaching the saw blade P, and the one-way clutch 8 positioned at the right end of the rotating shaft 41 in the left-right direction and capable of transmitting only the rotation of the rotating shaft 41 to be restricted in the forward rotation. Therefore, only the normal rotation of the output section 61 is permitted, and the reverse rotation is restricted. This makes it possible to easily attach the saw blade P without performing an operation of fixing the output portion 61.

The one-way clutch 8 in the electric circular saw 1 supports the rotary shaft 41 in a normal rotation. Thus, the bearing can be simplified without newly providing a bearing.

The electric circular saw 1 further includes a gear portion 5 between the motor 4 and the output portion 6 for reducing the rotation speed of the motor 4 and transmitting the rotation speed to the output portion 61. This enables a high torque to be generated in the output portion 61 even when the output of the motor 4 is small.

The motor 4 of the electric circular saw 1 includes a rotor 42 that rotates integrally with the rotating shaft 41. According to such a configuration, since the gear portion 5 is interposed between the rotary shaft 41 of the motor 4 supported by the one-way clutch 8 and the output portion 61, the one-way clutch 8 is located at a position separated from the output portion 61 generating the highest torque through the gear portion 5 during operation. This can restrict the rotation of the rotary shaft 41 at a position where the one-way clutch 8 is under a low load, and can ensure the durability of the electric circular saw 1.

Further, in the electric circular saw 1, the output portion 61 can rotate with high torque by a mechanism (two-stage speed reduction mechanism) that performs secondary speed reduction using the first gear, the second gear, and the third gear of the gear portion 5, and three rotation shafts (the rotation shaft 41, the intermediate shaft 54, and the output portion 61) are present in the rotation transmission path from the motor 4 to the output portion 61, but since the one-way overrunning clutch 8 is also used as a bearing of the rotation shaft 41, it is possible to suppress a load applied to the one-way overrunning clutch 8 and the gear housing 22, and to ensure durability of the electric circular saw 1.

Further, since the handle 3 is provided in the radial direction of the one-way clutch 8 (the one-way clutch 8 and the handle 3 are located on the same imaginary plane extending vertically and longitudinally), the rotational torque transmitted from the one-way clutch 8 to the gear housing 22 can be received on the same plane as the generation position of the one-way clutch when the tool bit is attached. Accordingly, when the tool bit is attached, the blade P can be stably attached because no twisting force acts on the electric circular saw 1.

The gear portion of the electric circular saw 1 further includes a gear housing 22 supporting the right end portion of the rotary shaft 41 and the gear portion 5, the gear portion 5 being located on the output portion 61 side with respect to the rotor 42 in the left-right direction, and the rotor 42 being located on the output portion 61 side in the left-right direction, and the gear housing 22 supports the right end portion of the rotary shaft 41 via the one-way clutch 8. Accordingly, the right end portion of the rotary shaft 41 and the gear portion 5 are supported by the gear housing 22, and therefore the overall length of the electric circular saw 1 can be suppressed. Further, since the gear housing 22 is formed so as to support the right end portion of the rotating shaft 41 by the one-way clutch 8, the gear housing 22 can be manufactured to a specification suitable for the one-way clutch 8, and the assembly of the electric circular saw 1 is facilitated by using the gear housing 22 to a specification suitable for the one-way clutch 8.

The gear housing 22 of the electric circular saw 1 is made of metal. Thus, the strength of the gear housing at the position where the one-way clutch 8 is disposed can be increased as compared with the case where a resin gear housing is used, and damage of the electric circular saw 1 from the position where the one-way clutch 8 is disposed can be suppressed.

Further, since the one-way clutch 8 is used as a bearing of the rotating shaft 41 of the motor 4 in the electric circular saw 1, the rotation of the rotating shaft can be restricted with a relatively simple structure.

In addition, since the motor 4 of the electric circular saw 1 is a DC brushless motor that is smaller than a conventional commutator motor, the size of the electric circular saw 1 can be reduced.

As described above, the electric circular saw 201 according to the second embodiment of the present invention includes the motor 4, the rotary shaft 41 extending in the left-right direction and rotated by the motor 4, the output portion 61 rotated by transmitting the rotational force of the rotary shaft 41 and to which the saw blade P can be attached and detached, and the dog clutch 210 positioned at the right end of the rotary shaft 41 in the left-right direction and capable of transmitting only the forward rotation to restrict the rotation of the rotary shaft 41. Therefore, only the normal rotation of the output section 61 is permitted, and the reverse rotation is restricted. This makes it possible to easily attach the saw blade P without performing an operation of fixing the output portion 61.

The electric circular saw 201 further includes a gear portion 5 between the motor 4 and the output portion 6 for reducing the rotation speed of the motor 4 and transmitting the rotation speed to the output portion 61. This enables a high torque to be generated in the output portion 61 even when the output of the motor 4 is small.

The motor 4 of the electric circular saw 201 includes a rotor 42 that rotates integrally with the rotating shaft 41. According to such a configuration, since the gear portion 5 is interposed between the output portion 61 and the motor 4 supported by the dog clutch 210 on the rotary shaft 41, the dog clutch 210 is located at a position separated from the output portion 61 generating the highest torque through the gear portion 5 during operation. This can restrict the rotation of the rotary shaft 41 at a position where the load on the dog clutch 210 is small, and can ensure the durability of the electric circular saw 210.

Further, since the electric circular saw 201 employs the dog clutch 210, the rotation of the rotary shaft 41 can be restricted with a relatively simple structure.

Further, since the motor 4 of the electric circular saw 201 is a DC brushless motor that is smaller than a conventional commutator motor, the size of the electric circular saw 1 can be reduced.

As described above, the circular saw 301 according to the third embodiment of the present invention includes the motor 304, the shaft 305A extending in the left-right direction and rotated by the motor 304, the output portion 306A rotated by the rotational force of the transmission shaft 305A and to which the saw blade Q can be attached and detached, and the one-way clutch 308 positioned at the left end of the shaft 305A in the left-right direction and capable of transmitting only the rotation of the shaft 305A restricted in the normal rotation. Therefore, only the normal rotation of the output unit 306A is permitted, and the reverse rotation is restricted. This makes it possible to easily detach the saw blade Q without performing an operation of fixing the output portion 306A.

In addition, the one-way clutch 308 in the table-type circular saw 301 supports the shaft 305A in the forward rotation. Thus, the bearing can be simplified without newly providing a bearing.

The table-type circular saw 301 includes a gear portion 305 between the motor 304 and the output portion 306A for reducing the rotation speed of the motor 304 and transmitting the rotation speed to the output portion 306A. Thus, even when the output of the motor 304 is small, a high torque can be generated in the output portion 306A.

The gear housing 302B of the circular saw 301 is made of metal. As a result, the strength of the gear housing at the position where the one-way clutch 8 is disposed can be increased as compared with the case where a resin gear housing is used, and damage to the table-type circular saw 301 from the position where the one-way clutch 308 is disposed can be suppressed.

Further, since the one-way clutch 308 is employed as a bearing of the shaft 305A, the rotation of the rotary shaft can be restricted with a relatively simple structure.

Further, since the motor 304 of the table-top circular saw 301 is a DC brushless motor that is smaller than a conventional commutator motor, the size of the table-top circular saw 301 can be reduced.

As described above, the disc grinder 401 according to the fourth embodiment of the present invention includes the motor 403, the rotating shaft 403A extending in the front-rear direction and rotated by the motor 403, the output portion 405A rotated by transmitting the rotational force of the rotating shaft 403A and detachably attached to the saw blade R, and the one-way clutch 8 located at the front end of the rotating shaft 403A in the front-rear direction and capable of transmitting only the rotation of the rotating shaft 403A restricted in the forward rotation. Therefore, only the normal rotation of the output unit 405A is permitted, and the reverse rotation is restricted. This makes it possible to easily attach the saw blade R without performing an operation of fixing the output portion 405A.

In addition, the one-way overrunning clutch 8 in the disc grinder 401 rotatably supports the rotating shaft 403A. This makes it possible to provide a simple structure without newly providing a bearing.

Further, since the disc grinder 401 employs the one-way clutch 8 as a bearing of the rotating shaft 403A of the motor 403, the rotation of the rotating shaft can be restricted with a relatively simple configuration.

The embodiments of the present invention are explained, but the electric power tool of the present invention is not limited to the above-mentioned embodiments, and various modifications are possible within the scope of the invention described in the claims. In the above embodiment, the electric circular saw 1 including the one-way clutch 8 for supporting the rotary shaft 41 only in the forward rotation is described by way of example, but the present invention is not limited to this, and any configuration may be applied as long as the one-way clutch is provided, and an electric tool such as a mower that performs work with a rotating tip tool and requires locking of the output portion (spindle) when the tip tool is attached and detached may be applied.

In the present embodiment, the regulating member is provided at only one location, but a plurality of regulating members may be provided. In this case, since the load applied at the time of reverse rotation can be dispersed and received by the plurality of regulating members, the life of the vehicle can be prolonged.

Description of the symbols

1-electric circular saw, 2-housing, 3-handle, 4-motor, 5-gear portion, 6-blade mounting portion, 7-main shaft locking piece, 8-one-way overrunning clutch, 9-base, 21-motor housing, 22-gear housing, 41-rotation axis, 42-rotor, 44-restricted rotation portion, 46-first bearing, 51-first gear, 52-second gear, 53-third gear, 55-second bearing, 56-third bearing, 61-output portion, 64-bolt, 65-fourth bearing, 66-fifth bearing, 73-restricted portion, 81-barrel portion, 82-roller, 83-spring.

Claims

1. An electric tool is characterized in that the electric tool is provided with a power supply unit,

comprising: a motor;

a rotating shaft extending in a predetermined direction and rotated by the motor;

an output part which rotates by transmitting the rotating force of the rotating shaft and can assemble and disassemble the front end tool;

a speed reduction mechanism for reducing the speed of rotation of the rotating shaft and transmitting the rotation to the output unit; and

a restricting member located at one end of the rotary shaft in the predetermined direction,

the restricting member permits rotation of the rotary shaft in one of forward and reverse directions and prohibits rotation in the other direction.

2. The power tool of claim 1,

the device has a fixing mechanism for limiting the rotation of the output part in the forward and reverse directions.

3. The power tool of claim 1,

the motor has a rotor that rotates integrally with the rotating shaft.

4. The power tool of claim 3,

the speed reduction mechanism is located on the output side with respect to the rotor in the predetermined direction,

the electric power tool further includes a gear housing that supports an end portion of the rotary shaft located on the output side with respect to the rotor in the predetermined direction and the speed reduction mechanism,

the gear housing supports the end portion via the restricting member.

5. The power tool of claim 4,

the gear housing is made of metal.

6. The electric power tool according to any one of claims 1 to 5,

the limiting member is a one-way overrunning clutch.

7. The electric power tool according to any one of claims 1 to 5,

the motor is a brushless motor.

8. The power tool of claim 6,

the motor is a brushless motor.

9. The electric power tool according to any one of claims 3 to 5,

the motor control device is provided with a shell for accommodating the motor and a base for supporting the shell, wherein the shell is provided with a handle which can be held, and the limiting component is arranged in the shell at a position between the handle and the base.

10. The power tool of claim 9,

the rotor is provided with a fan for cooling the motor, and the handle is positioned in the radial direction of the regulating member when the radial direction of the fan is defined as the radial direction.