WO2012090711A1

WO2012090711A1 - Work tool

Info

Publication number: WO2012090711A1
Application number: PCT/JP2011/078961
Authority: WO
Inventors: 洋規生田; 祐太松浦; 順平紙元; 洋介西尾
Original assignee: 株式会社マキタ
Priority date: 2010-12-27
Filing date: 2011-12-14
Publication date: 2012-07-05
Also published as: JP2012135844A

Abstract

[Problem] To provide an effective technology for preventing wear and tear related to power transmission in a work tool having a power transmission mechanism for transmitting drive-motor power to the tip of the tool. [Solution] This work tool is an electric screwdriver (101) that has a drive motor (111) and a power transmission mechanism (131) for transmitting the power of the drive motor (111) to a driver bit (119), and that tightens screws on a material being processed via the driver bit (119). The power transmission mechanism (131) comprises: a drive gear (133) that is rotated and driven by the drive motor (111); a spindle (117) that holds the driver bit (119) and is disposed spaced apart from the drive gear (133) in the longitudinal axis direction of the driver bit (119), and to which relative rotation between itself and the drive gear (133) is allowed; a magnet (134) provided in the drive gear (133); and a conductor (137) provided to the spindle (117) and disposed at a prescribed distance from the magnet (134). In a state where the magnet (134) and the conductor (137) are disposed with a prescribed distance therebetween, when the drive gear (133) rotates relative to the drive gear (133), an eddy current produced by the magnetic flux of the magnet (134) flows through the conductor (137) and as a result power is transmitted from the drive gear (133) to the spindle (117).

Description

Work tools

The present invention relates to a work tool having a power transmission mechanism for transmitting power of a drive motor to a tip tool.

JP-A-5-253854 discloses a screw tightening machine (screw driver) used for screw tightening work. The power transmission mechanism of the screw tightener is configured such that a driving side member that is rotationally driven by a driving motor and a driven side member that is connected to a tip tool are engaged by a meshing clutch so that the power of the driving motor is It is configured to transmit to the tool.

The screw tightening machine disclosed in the above publication employs a power transmission mechanism that generates torque transmission when the driving side member and the driven side member come into contact with each other. There is concern about the problem of
Therefore, when designing this type of work tool such as a screw tightener, a technique effective for preventing wear of the power transmission portion between the drive motor and the tip tool is required.

The present invention has been made in view of the above points, and an object of the present invention is to provide a work tool having a power transmission mechanism effective for preventing wear related to power transmission.

In order to solve the above problems, the working tool according to the present invention according to the claims is configured.

The working tool according to a preferred embodiment of the present invention is a working tool that performs a predetermined machining operation on a workpiece through a tip tool, and has at least a drive motor and a power transmission mechanism as its constituent elements. The tip tool may be a component of the work tool or may be a separate component from the work tool. The drive motor is configured as an electric or air-driven motor. The power transmission mechanism is configured as a mechanism for transmitting the power of the drive motor to the tip tool. The power transmission mechanism further includes a driving side member, a driven side member, a magnet, and a conductor. The drive side member is configured as a member that is rotationally driven by a drive motor. The driven member is configured as a member that holds the tip tool, is disposed away from the drive side member in the long axis direction of the tip tool, and is allowed to rotate relative to the drive side member. The magnet is provided on one of the driving side member and the driven side member. The conductor is provided on the other of the driving side member and the driven side member, and is disposed at a predetermined distance from the magnet. That is, a mode in which the magnet is provided on the driving side member and the conductor is provided on the driven side member, and a mode in which the magnet is provided on the driven side member and the conductor is provided on the driving side member are included.

Then, in a state where the magnet and the conductor are arranged at a predetermined distance, an eddy current flows through the conductor due to the magnetic flux of the magnet during the relative rotation operation of the driving side member with respect to the driven side member. Power is transmitted from the driven member to the driven member. According to such a configuration, when power is transmitted from the driving side member to the driven side member, the driving side member and the driven side member are separated from each other and do not come into contact with each other (a non-contact state). Therefore, it is possible to reliably prevent the occurrence of wear related to power transmission. In addition, since the drive side member and the driven side member are not in contact with each other, a work tool that directly connects the drive side member and the driven side member coaxially with respect to misalignment between the drive side member and the driven side member. Therefore, there is an advantage that a high degree of dimensional accuracy is not required.

In the work tool according to a further aspect of the present invention, the conductor is preferably configured as a non-magnetic material. Further, it is preferable that the driving side member and the driven side member are configured to be relatively movable in the long axis direction of the tip tool and biased in a direction away from each other. According to such a configuration, since the conductor is a non-magnetic material, the attracting action of the conductor and the magnet does not affect the operation in which the driven member approaches the driving member. In addition, it becomes possible to easily set the driving side member and the driven side member at a position where power transmission from the driving side member to the driven side member is released.

The work tool according to a further aspect of the present invention is preferably configured as a screw tightening machine that is used for screw tightening work. It is preferable that the power transmission mechanism further includes a support mechanism and an urging mechanism. The support mechanism functions to support the driven member so that the driven member can move in the long axis direction of the tip tool with respect to the driving member. The urging mechanism performs a function of generating an urging force such that the driving side member and the driven side member are separated from each other. In this configuration, the driven-side member is pushed away from the driving-side member together with the tip tool against the biasing force of the biasing mechanism during the screw tightening operation, so that the magnet and the conductor are arranged at a predetermined distance. A state is formed. Thereby, a power transmission mechanism suitable for a screw tightening machine used for screw tightening work among various work tools is realized.

In the work tool according to a further aspect of the present invention, the drive side member is directly connected to the motor shaft of the drive motor, the driven side member constitutes an output shaft directly connected to the tip tool, and the motor shaft It is preferable that the output shaft be arranged coaxially. Moreover, it is preferable that the driven side member is configured to be spaced apart from the driving side member so that a state in which the magnet and the conductor are arranged at a predetermined distance is always formed. Thereby, a power transmission mechanism suitable for a die grinder that performs a grinding work, a polishing work, a cutting work or the like of a workpiece among various work tools is realized.

According to the present invention, it is possible to prevent wear associated with power transmission in a work tool having a power transmission mechanism for transmitting the power of the drive motor to the tip tool. Other characteristics, operations, and effects of the present invention can be readily understood with reference to the present specification, claims, and accompanying drawings.

It is sectional drawing which shows the whole structure of the electric screwdriver 101 of this Embodiment. It is the elements on larger scale of the A area | region in FIG. 1, Comprising: The initial state which is not performing the screw fastening operation | work is shown. FIG. 3 is a view showing a cross-sectional structure taken along line BB in FIG. 2. It is the elements on larger scale of A area | region in FIG. 1, Comprising: The state at the time of screw fastening operation | work is shown. It is sectional drawing which shows the whole structure of the electric die grinder 201 of another embodiment. It is the elements on larger scale of C area | region in FIG. It is a figure which shows the cross-section regarding the DD line | wire in FIG.

The configurations and methods according to the above and the following description are separately or separately from other configurations and methods in order to realize the manufacture and use of the “work tool” according to the present invention and the use of the components of the “work tool”. Can be used in combination. Exemplary embodiments of the present invention include these combinations and will be described in detail with reference to the accompanying drawings. The following detailed description is only to teach those skilled in the art with detailed information to implement preferred embodiments of the invention, and the scope of the invention is not limited by the detailed description, but is limited by the scope of the claims. It is determined based on the description. For this reason, combinations of configurations and method steps in the following detailed description are not all essential to implement the present invention in a broad sense, but are described in detail with reference numerals in the accompanying drawings. However, only representative embodiments of the present invention are disclosed.

Hereinafter, an embodiment of a work tool according to the present invention will be described in detail with reference to the drawings. In the present embodiment, as an example of a work tool, an electric screwdriver used to perform a screw tightening operation will be described. FIG. 1 shows the overall configuration of an electric screwdriver 101 (also referred to as a “screw tightener”) according to the present embodiment, and FIG. 2 shows a partially enlarged view of region A in FIG. Has been.

As shown in FIG. 1, the electric screw driver 101 is mainly configured by a main body 103, a hand grip 109, and a driver bit 119 when viewed generally. The main body 103 constitutes a work tool main body of the electric screw driver 101. The handgrip 109 is connected to the opposite side of the driver bit 119 across the main body 103 and is configured as a handle portion that is gripped by an operator. The driver bit 119 is configured as a long tool (tip tool) that is detachably attached to the tip region (right side in FIG. 1) of the main body 103 via a spindle 117. The driver bit 119 may be a component of the electric screw driver 101 or may be a component separate from the electric screw driver 101. The driver bit 119 here corresponds to the “tip tool” in the present invention.

In the present embodiment, for convenience, the driver bit 119 side of the electric screwdriver 101 is defined as the “front side” or “front side” of the work tool or the components of the work tool, and the handgrip 109 side is defined. Are defined as “rear side” or “rear side” of the work tool or components of the work tool. 1 is defined as the major axis direction of the driver bit 119.

The main body 103 is mainly composed of a motor housing 105 and a gear housing 107. The motor housing 105 is configured as a housing (housing body) that houses at least a drive motor (also referred to as “electric motor”) 111. The drive motor 111 is driven by an operation of the trigger 109 a provided on the hand grip 109 by the operator. Specifically, when the trigger 109a is pulled, the drive motor 111 is driven by energization control, and when the pull operation is released, the drive motor 111 is stopped driving. The drive motor 111 here corresponds to a “drive motor” in the present invention. The gear housing 107 is configured as a housing (accommodating body) that accommodates at least the power transmission mechanism 131. A locator 123 that defines the screwing depth by the driver bit 119 is provided at the front end of the main body 103.

As shown in FIG. 2, the spindle 117 is relatively movable in the major axis direction of the driver bit 119 via a bearing 121 that receives a radial load in the radial direction, and is rotatable around the major axis of the driver bit 119. Is attached to the gear housing 107. That is, the bearing 121 has at least a function of supporting the spindle 117 so that the spindle 117 constituting the driven member can move in the major axis direction of the driver bit 119. Therefore, the bearing 121 here constitutes the “support mechanism” in the present invention.

The front end portion 117a on the front side of the spindle 117 is provided with a bit insertion hole 117b into which the driver bit 119 is inserted. The driver bit 119 inserted into the bit insertion hole 117b includes a small diameter portion 119a whose outer diameter is relatively reduced. Further, a steel ball 118 (steel ball) urged in a radial direction toward the bit insertion hole 117b by a ring-shaped leaf spring (not shown) is disposed at the front end portion 117a of the spindle 117. Is engaged with the small diameter portion 119a of the driver bit 119 in the radial direction, thereby holding the driver bit 119. The spindle 117 here has a function of holding the driver bit 119 and constitutes a “driven member” in the present invention.

The power transmission mechanism 131 functions to transmit the rotational output of the drive motor 111 to the spindle 117 and the driver bit 119 and to function as a clutch that blocks the transmission. As shown in FIG. 2, the power transmission mechanism 131 is composed mainly of a drive gear 133, a magnet 134, a drive shaft 135, a spindle 117, a conductor 137, and a coil spring 139. The power transmission mechanism 131 here corresponds to the “power transmission mechanism” in the present invention.

The drive gear 133 is opposed to the rear end portion 117c on the rear side of the spindle 117, and is integrally formed with the long drive shaft 135 in the rotational direction, and meshes with the motor shaft 115 of the drive motor 111. , And is driven to rotate around the drive shaft 135. With respect to the drive gear 133, the spindle 117 is disposed away from the drive gear 133 with respect to the major axis direction of the driver bit 119, and relative rotation with the drive gear 133 is allowed. The drive gear 133 and the drive shaft 135 here are drive side members that are rotationally driven by the drive motor 111, and constitute the “drive side member” in the present invention.

The drive gear 133 is pivotally supported via front and

rear bearings

141 and 142 that receive a thrust load in the major axis direction of the driver bit 119 (also defined as the major axis direction of the drive shaft 135). . The drive gear 133 has a facing surface 133a that faces the rear end portion 117c of the spindle 117, and a plurality of magnets (also referred to as “permanent magnets”) 134 are embedded in the facing surface 133a. Each magnet 134 is arranged so that the front end surface thereof is flush with the facing surface 133 a of the drive gear 133. The magnet 134 here corresponds to a “magnet” in the present invention.

The drive shaft 135 is configured to extend on the same axis as the driver bit 119. The rear end portion 117c on the rear side of the spindle 117 is formed with a spring accommodating hole 117d having a circular cross section that is open at the rear. The front end portion 135a on the front side of the drive shaft 135 is inserted into the spring accommodating hole 117d, and is rotatably supported via a bearing 143 that receives a radial radial load. The rear end portion on the rear side The shaft 135b is rotatably supported by a bearing 144 that receives a radial radial load.

The conductor 137 is integrally attached around the rear end portion 117c of the spindle 117. In the present embodiment, the conductor 137 is disposed away from the magnet 134. The conductor 137 is typically configured as a nonmagnetic material containing aluminum or copper, and has a facing surface 137a facing the facing surface 133a of the drive gear 133. By configuring the conductor 137 as a non-magnetic material, the attracting action of the conductor 137 and the magnet 134 has an influence on the operation in which the spindle 117 approaches the drive gear 133 in accordance with the pushing operation during the screw tightening operation. There is nothing. The conductor 137 here corresponds to the “conductor” in the present invention.

The coil spring 139 is disposed around the front end portion 135a of the drive shaft 135, and is housed together with the front end portion 135a of the drive shaft 135 in the spring housing hole 117d of the spindle 117. The coil spring 139 functions as a compression coil spring that generates an urging force (elastic urging force) such that the spindle 117 and the drive gear 133 are separated from each other in the longitudinal direction of the driver bit 119. Therefore, the front end 139a on the front side of the coil spring 139 is attached to the spindle 117 side, and the rear end 139b on the rear side is attached to a stopper 145 disposed on the opposite side of the drive gear 133 with the bearing 142 interposed therebetween. It is attached. The coil spring 139 here constitutes an “urging mechanism” in the present invention.

The coil spring 139 has a position where the spindle 117 is close to the drive gear 133 (also referred to as “push-in position”) and a position where the spindle 117 is separated from the drive gear 133 (“push-in release position” or “initial state before push-in operation”). (Also referred to as “position”). That is, during the pushing operation of the driver bit 119, the spindle 117 is pushed in the direction close to the drive gear 133 together with the driver bit 119 against the elastic biasing force of the coil spring 139, and the rear end portion 117c is on the drive gear 133 side. It comes into contact with a stopper 145 that is a stop portion of the. Thus, the minimum separation distance d1 (separation distance at the pushing position) between the facing surface 133a of the drive gear 133, that is, the end surface of the magnet 134, and the facing surface 137a of the conductor 137 is defined. The minimum separation distance d1 here corresponds to the “predetermined distance” in the present invention. On the other hand, in the spindle 117, when the driver bit 119 is pushed out, the conductor 137 provided around the rear end portion 117 c comes into contact with the stopper 108 which is a stop portion on the gear housing 107 side. Thereby, the maximum separation distance d2 (separation distance at the push-in release position) between the facing surface 133a of the drive gear 133, that is, the end surface of the magnet 134, and the facing surface 137a of the conductor 137 is defined.

For the number and arrangement of the magnets 134 in the drive gear 133 configured as described above, reference is made to FIG. 3 showing a cross-sectional structure with respect to the line BB in FIG. As shown in FIG. 3, a plurality of (12 in the form shown in FIG. 3) magnets 134 are embedded at equal intervals in the circumferential direction of the facing surface 133 a on the circular facing surface 133 a of the drive gear 133. . Particularly in the present embodiment, the opposing surface 133a side is indicated by an N-pole magnet 134 (a magnet indicated by “N” in FIG. 3) and the opposing surface 133a side is indicated by an S-pole magnet 134 (indicated by “S” in FIG. 3). Magnets) are alternately arranged. According to such a configuration, it is possible to smooth the rotation operation of the conductor 137 with respect to the drive gear 133. Note that the number and arrangement of the magnets 134 can be appropriately changed as necessary. For example, a configuration in which 1 to 11 magnets 134 having N or S poles on the facing surface 133a side or 13 or more magnets 134 are provided in the drive gear 133 may be employed.

2 and 4 are referred to for the operation of the electric screw driver 101 having the above-described configuration. The state shown in FIG. 2 is an initial state where the screw tightening operation is not performed. In this initial state, the spindle 117 is moved forward by the elastic biasing force of the coil spring 139. In this case, the rotation output of the drive gear 133 is not transmitted to the spindle 117. Thereafter, when the drive motor 111 is driven by the pulling operation of the trigger 109a, the drive gear 133 is rotationally driven through the motor shaft 115 of the drive motor 111, but the opposing surface 137a of the conductor 137 is on the drive gear 133 side. Since the magnet 134 is separated from the magnet 134 by the above-described maximum separation distance d2, a load sufficient to rotate the conductor 137 due to the magnetic flux of the magnet 134 is not generated, and the spindle 117 is not rotationally driven. The electric screwdriver 101 is in an idling state.

In this idling state, the main body 103 is moved forward (to the workpiece side) to actually perform the screw tightening operation, and the screw (not shown) attached to the driver bit 119 is pressed by the operator by the pressing force. The spindle 117 is pushed together with the driver bit 119 together with the driver bit 119 against the elastic biasing force of the coil spring 139. That is, the spindle 117 retreats relatively to the left side in FIG. 2 with respect to the main body 103 and the drive gear 133, and moves to a predetermined pushing position.

FIG. 4 is a partially enlarged view of region A in FIG. 1 and shows a state during the screw tightening operation. This state shown in FIG. 4 is a state in which the spindle 117 comes close to the drive gear 133 in accordance with the pushing operation of the driver bit 119 and is set to the pushing position described above. In this state, the rear end portion 117c of the spindle 117 is in contact with the stopper 145 on the drive gear 133 side, so that the spindle 117 is prevented from further approaching the drive gear 133. At this time, the opposing surface 137a of the conductor 137 is separated from the magnet 134 on the drive gear 133 side by the aforementioned minimum separation distance d1. The minimum separation distance d1 is preferably set as appropriate according to the number and type of magnets 134, the material of the conductor 137, and the like so as to achieve a desired form of power transmission in the power transmission mechanism 131.

In the state where the spindle 117 is set to the indented position or in the process of moving to the indented position, a load sufficient to rotationally drive the conductor 137 due to the eddy current flowing through the conductor 137 due to the magnetic flux of the magnet 134. The generated power is transmitted to the spindle 117 so that the power of the drive gear 133 in the rotationally driven state is transmitted. This power transmission is caused by rotating the magnet 134 on the drive gear 133 side along the opposing surface 137a of the conductor 137 and rotating the conductor 137 in the rotation direction of the magnet 134, so-called "Arago disk". The principle is used.

Specifically, in a state where the magnet 134 and the conductor 137 are arranged with a minimum separation distance d1, the magnetic flux moves on the conductor 137 by the rotation of the magnet 134, and the magnetic flux penetrates the conductor 137. As a first step, an induced electromotive force due to the magnetic flux is generated in the conductor 137 based on Fleming's right-hand rule, and an eddy current flows in the conductor 137. When an eddy current flows through the conductor 137, as a second step, an electromagnetic force is generated that pulls the conductor 137 in the tangential direction between the eddy current and the magnetic flux of the magnet 134 according to Fleming's left-hand rule. It is pulled by the magnet 134 and rotates together with the spindle 117 in the moving direction of the magnet 134. At this time, since the induced electromotive force is generated when the magnetic flux moves on the conductor 137 and the magnetic flux penetrates the conductor 137, the rotational speeds of the conductor 137 and the spindle 117 around the drive shaft 135 are: It becomes slower than the rotational speed of the magnet 134 and the drive gear 133. Thus, the rotational output of the drive motor 111 is transmitted to the spindle 117 and the driver bit 119 via the power transmission mechanism 131, and the actual screw tightening operation is performed by the rotationally driven driver bit 119.

On the other hand, when the screw tightening operation is finished and the screw pressing operation by the driver bit 119 is released, the spindle 117 moves together with the driver bit 119 in a direction away from the drive gear 133 according to the elastic biasing force of the coil spring 139. Move in one piece. That is, the spindle 117 moves forward relative to the right side in FIG. 2 with respect to the main body 103, moves to a predetermined push release position, and returns to the state shown in FIG. In this return state shown in FIG. 2, the conductor 137 abuts against the stopper 108 on the gear housing 107 side, thereby preventing the spindle 117 from being further separated from the drive gear 133.

In the process in which the spindle 117 moves to the push-in release position, the power transmission in which the power of the drive gear 133 in the rotational drive state is transmitted to the spindle 117 is released. This release of power transmission is caused by the influence of the magnetic flux of the magnet 134 on the conductor 137 weakening as the spindle 117 moves away from the drive gear 133. Thus, the operation in which the rotational output of the drive motor 111 is transmitted to the spindle 117 and the driver bit 119 via the power transmission mechanism 131 is released, and the above-described electric screw driver 101 enters the idling state. As described above, in this embodiment, by using the elastic biasing force of the coil spring 139, the drive gear 133 and the spindle 117 can be easily set to a position where the power transmission from the drive gear 133 to the spindle 117 is released. It becomes possible. Further, the driving operation of the driving motor 111 is stopped by releasing the pulling operation of the trigger 109a.

According to the power transmission mechanism 131 configured as described above, when power is transmitted from the drive gear 133 constituting the drive side member to the spindle 117 constituting the driven side member, the drive side member and the driven side member are separated from each other. Therefore, no contact is made (because it is a non-contact state), so that it is possible to reliably prevent the occurrence of wear related to power transmission. Further, since the drive gear 133 that constitutes the drive side member and the spindle 117 that constitutes the driven side member are in a non-contact state, the misalignment between the drive side member and the driven side member can be avoided. There is an advantage that a high degree of dimensional accuracy as required for a work tool for directly connecting members on the same axis is not required. Moreover, the power transmission mechanism suitable for the screwing machine especially used for screwing work among various work tools can be realized.

In the above embodiment, the case where the present invention is applied to the electric screw driver 101 as a work tool has been described. However, the present invention can also be applied to work tools other than the electric screw driver. Reference is made to FIGS. 5 to 7 for an example of a working tool according to another embodiment. FIG. 5 shows an example of a working tool according to another embodiment, which is an electric grinder 201 (““ grinder work ”) used to perform a grinding work, a grinding work, a cutting work, or the like (also referred to as“ grinding work ”). FIG. 6 shows a partially enlarged view of a region C in FIG. 5. FIG. 7 shows a cross-sectional structure taken along line DD in FIG.

As shown in FIG. 5, the electric die grinder 201 is composed mainly of a main body 203 and a grindstone 219 when viewed generally. The main body 203 constitutes a work tool main body of the electric die grinder 201. The grindstone 219 is configured as a long tool (tip tool) that is detachably attached to the tip region (right side in FIG. 5) of the main body 203 via a spindle 217. The grindstone 219 may be a component of the electric die grinder 201 or may be a component separate from the electric die grinder 201. The grindstone 219 here corresponds to the “tip tool” in the present invention.

The main body 203 is mainly composed of a motor housing 205 and a gear housing 207. The motor housing 205 is configured as a housing (housing body) that houses at least a drive motor (also referred to as “electric motor”) 211. The motor housing 205 also has a function as a grip part whose outer surface is gripped by an operator. The gear housing 207 is configured as a housing (accommodating body) that accommodates at least the power transmission mechanism 231. The drive motor 211 here corresponds to the “drive motor” in the present invention.

The spindle 217 is attached to the gear housing 207 so as to be rotatable around the long axis of the grindstone 219. The spindle 217 is provided with a fixing member 218 that fastens and fixes the grindstone 219 on the front side thereof. The spindle 217 has a function of holding the grindstone 219 and constitutes an output shaft directly connected to the grindstone 219. In this embodiment, the spindle 217 is arranged coaxially with the motor shaft 215 of the drive motor 211. Therefore, the spindle 217 here corresponds to the “driven member” and the “output shaft” in the present invention.

The power transmission mechanism 231 functions to transmit the rotational output of the drive motor 211 to the spindle 217 and the grindstone 219. As shown in FIG. 6, the power transmission mechanism 231 is mainly composed of a drive body 233, a magnet 234, a spindle 217, and a conductor 237. The power transmission mechanism 231 here corresponds to the “power transmission mechanism” in the present invention.

The driving body 233 is disposed on the rear side of the spindle 217 and is separated from the spindle 217. The drive body 233 is directly connected to the motor shaft 215 and is driven to rotate around the motor shaft 215. The drive body 233 is pivotally supported so as to be relatively rotatable via a bearing 241 that receives a radial load in the radial direction. On the front side of the driving body 233, a facing surface 233a facing the conductor 237 is formed, and a plurality of magnets 234 similar to the above-described magnet 134 are embedded in the facing surface 233a. Each magnet 234 is configured such that the front end surface thereof is flush with the facing surface 233a of the driving body 233.

The conductor 237 is provided integrally with the rear end 217b on the rear side of the spindle 217. Similar to the conductor 137, the conductor 237 is typically configured as a nonmagnetic material containing aluminum or copper, and has a facing surface 237a facing the facing surface 233a of the driver 233. The conductor 237 here corresponds to the “conductor” in the present invention. On the other hand, the spindle 217 in which the conductor 237 is integrated with the rear end 217b has a front end 217a on the front side via a bearing 242 that receives a radial radial load, and the rear end 217b has a radial radial. It is supported so as to be relatively rotatable via a bearing 243 that receives a load. With the above configuration, the spindle 217 is disposed away from the driving body 233 so that the state in which the magnet 234 and the conductor 237 are always disposed at a predetermined distance similar to the aforementioned minimum separation distance d1 is formed. Will be.

Regarding the number and arrangement of the magnets 234 in the driving body 233 having the above-described configuration, as shown in FIG. 7, a plurality of circular opposing surfaces 233a of the driving body 233 are arranged at equal intervals in the circumferential direction of the opposing surface 233a. Magnets 234 (eight in the form shown in FIG. 7) are embedded. Particularly in the present embodiment, the opposing surface 233a side is indicated by an N-pole magnet 234 (a magnet indicated by “N” in FIG. 7) and the opposing surface 233a side is indicated by an S-pole magnet 234 (“S” in FIG. 7). Magnets) are alternately arranged. According to such a configuration, it is possible to achieve smooth rotation of the conductor 237 relative to the drive body 233. Note that the number and arrangement of the magnets 234 can be appropriately changed as necessary. For example, a configuration in which 1 to 7 magnets 234 having N or S poles on the facing surface 233a side and nine or more magnets 234 are provided in the driving body 233 may be employed.

FIG. 6 is referred to for the operation of the electric die grinder 201 configured as described above. As shown in FIG. 6, in this electric die grinder 201, the opposing surface 237a of the conductor 237 and the opposing surface 233a of the driving body 233 (end surface of the magnet 234) are always arranged with a predetermined separation distance therebetween. Similar to the above-described embodiment shown in FIG. 4, a state in which the power of the driving body 233 can be transmitted to the spindle 217 is formed. Therefore, when the drive motor 211 is driven by an operation on an operation member (not shown) to actually perform the grinder work, power transmission is performed in which the power of the drive body 233 in the rotational drive state is transmitted to the spindle 217. The This power transmission is generated by rotating the magnet 234 on the drive body 233 side along the facing surface 237a of the conductor 237 and rotating the conductor 237 in the rotation direction of the magnet 234.

Specifically, the magnetic flux moves on the conductor 237 by the rotation of the magnet 234, and the magnetic flux penetrates the conductor 237. Therefore, as the first step, the conductor 237 is subjected to the right-hand rule of Fleming. An induced electromotive force due to the magnetic flux is generated, and an eddy current flows through the conductor 237. When an eddy current flows through the conductor 237, as a second stage, an electromagnetic force is generated that pulls the conductor 237 in the tangential direction between the eddy current and the magnetic flux of the magnet 234 according to Fleming's left-hand rule. It is pulled by the magnet 134 and rotates together with the spindle 117 in the moving direction of the magnet 234. At this time, since the induced electromotive force is generated when the magnetic flux moves on the conductor 237 and the magnetic flux penetrates the conductor 237, the rotational speeds of the conductor 237 and the spindle 217 around the drive shaft 235 are as follows. It becomes slower than the rotational speed of the magnet 234 and the driving body 233. Thus, the rotational output of the drive motor 211 is transmitted to the spindle 217 and the grindstone 219 via the power transmission mechanism 231 and the actual grinder work is performed by the grindstone 219 that is rotationally driven.

On the other hand, when the grinder operation is completed and the drive motor 211 is stopped, the relative rotation operation of the drive body 233 with respect to the driver bit 217, that is, the relative rotation operation of the magnet 234 with respect to the conductor 237 is stopped. The power transmission from the drive body 233 to the spindle 217 is stopped.

According to the power transmission mechanism 231 having the above configuration, when power is transmitted from the drive body 233 constituting the drive side member to the spindle 217 constituting the driven side member, the drive side member and the driven side member are separated from each other. Therefore, it is possible to reliably prevent the occurrence of wear associated with power transmission. Further, since the driving body 233 constituting the driving side member and the spindle 217 constituting the driven side member are not in contact with each other, the misalignment between the driving side member and the driven side member is caused by the driving side member and the driven side. There is an advantage that a high degree of dimensional accuracy as required for a work tool for directly connecting members on the same axis is not required. Moreover, it is possible to realize a power transmission mechanism suitable for a die grinder that performs a grinding work, a grinding work, a cutting work, or the like of a workpiece among various work tools.

[Other Embodiments]
In addition, this invention is not limited only to said embodiment, A various application and deformation | transformation can be considered. For example, each of the following embodiments to which the above embodiment is applied can be implemented.

In the power transmission mechanisms 113 and 213 of the above-described embodiment, the case where the magnet is arranged on the driving side member and the conductor is arranged on the driven side member has been described. However, in the present invention, the conductor is arranged on the driving side member. A configuration in which a magnet is arranged on the driven member can also be adopted.

In the above-described embodiment, the case where the

conductors

137 and 237 are configured as nonmagnetic materials has been described. However, the conductors can also be configured as magnetic materials as necessary.

Moreover, although the case where this invention was applied to the power transmission mechanism of an electric screwdriver or an electric die grinder was described in the said embodiment, in order to transmit the motive power of a drive motor to a tip tool other than these work tools. The present invention can also be applied to a work tool having a power transmission mechanism. In this case, the drive motor may be configured as an air-driven motor other than the electric motor.

DESCRIPTION OF SYMBOLS 101 Electric screwdriver 103 Main part 105 Motor housing 107 Gear housing 108 Stopper 109 Hand grip 109a Trigger 110 Drive motor 111 Drive motor 115 Motor shaft 117 Spindle 117a Front end 117b Bit insertion hole 117c Rear end 117d Spring accommodation hole 118 Steel ball 119 Driver bit 119a Small diameter portion 121 Bearing 123 Locator 131 Power transmission mechanism 133 Driving gear 133a Opposing surface 134 Magnet 135 Driving shaft 135a Front end portion 135b Rear end portion 137 Conductor 137a Opposing surface 139 Coil spring 139a Front end portion 139b

Rear end portions

141, 142, 143, 144 Bearing 145 Stopper 201 Electric die grinder 203 Main body 205 Motor housing 205 Gear housing 211 Drive motor 217 Spin End 217a Front end 217b Rear end 218 Fixing member 219 Grinding wheel 231 Power transmission mechanism 233 Driver 233a Opposing surface 234 Magnet 237 Conductor

237a Opposing surfaces

241, 242, 243 Bearing

Claims

A work motor having a drive motor and a power transmission mechanism for transmitting the power of the drive motor to a tip tool, and performing a predetermined machining operation on a workpiece through the tip tool,
The power transmission mechanism is
A drive side member that is rotationally driven by the drive motor;
A driven-side member that holds the tip tool, is disposed apart from the drive-side member in the longitudinal direction of the tip tool, and is allowed to rotate relative to the drive-side member;
A magnet provided on any one of the driving side member and the driven side member;
A conductor provided on the other of the driving side member and the driven side member and disposed at a predetermined distance from the magnet,
In a state where the magnet and the conductor are arranged at a predetermined distance, an eddy current flows through the conductor due to the magnetic flux of the magnet during the relative rotation operation of the driving side member with respect to the driven side member. Thus, the working tool is configured to transmit power from the driving side member to the driven side member.
The work tool according to claim 1,
The conductor is configured as a non-magnetic material, and the driving side member and the driven side member are relatively movable in a major axis direction of the tip tool and are biased in a direction away from each other. Work tool to do.
The work tool according to claim 1 or 2,
The work tool is configured as a screw tightening machine used for screw tightening work,
The power transmission mechanism further includes a support mechanism that supports the driven member so that the driven member can move in the major axis direction of the tip tool with respect to the driving member, and the driving member. An urging mechanism for generating an urging force that separates the driven side members from each other;
The driven side member is pushed in a direction close to the driving side member together with the tip tool against the biasing force of the biasing mechanism during the screw tightening operation, so that the magnet and the conductor are separated from each other by the predetermined distance. A working tool characterized in that a state of being arranged is formed.
The work tool according to claim 3,
The power transmission mechanism further includes a stopper attached to the drive side member via a bearing so as to be relatively rotatable,
When the driven-side member is pushed in a direction approaching the driving-side member, an end of the driven-side member in the long axis direction comes into contact with the stopper, whereby the magnet and the conductor are separated from each other by the predetermined distance. A working tool characterized in that a state of being arranged is formed.
The work tool according to claim 1,
The drive side member is directly connected to a motor shaft of the drive motor, the driven side member constitutes an output shaft directly connected to the tip tool, and the motor shaft and the output shaft are coaxial. Is the configuration placed above,
The driven side member is configured to be spaced apart from the driving side member so that the state in which the magnet and the conductor are spaced apart from each other by a predetermined distance is always formed. Work tools.