Impact Tools

Abstract

The present invention provides an impact tool. A hammer drill (101) has a cooling fan (7), which has a blade portion (72) and is rotated by the rotational force of a rotating component (26). The cooling fan (7) includes a resin component and a metal component (weight portion (73)). When viewed from the rotation axis A2 direction of the cooling fan (7), the metal component is at least arranged at a position that overlaps with the range of the diameter of the cooling fan (7) equipped with the blade portion (72). Accordingly, in an impact tool using a brushless motor, it is helpful to increase the inertia moment related to the impact energy.

Description

Technical Field

[0001] The present invention relates to an impact tool for driving a top tool. Background Art

[0002] As a motor mounted on an electric tool, it is known to use a brushless motor. By using a brushless motor in an electric tool, for example, the following advantages can be obtained. Compared with a commutator motor (hereinafter also referred to as a brushed motor), a brushless motor can eliminate the need to replace brushes. In addition, the motor itself can be made small and light, and the energy conversion efficiency can be improved. For example, the following patent document 1 discloses an impact tool using a brushless motor.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Publication No. 2018-79557 Summary of the invention

[0006] [Technical problem to be solved by the invention]

[0007] The impact tool processes the workpiece by converting the rotational force of the motor into impact energy. The magnitude of the impact energy output from the impact tool depends on the inertia moment of the motor. In terms of its structure, the brushless motor has a smaller inertia moment of the rotating parts including the rotor and the motor shaft than a brushed motor with the same output. Therefore, when a brushless motor is used in an impact tool, the load current for outputting the required impact energy increases compared to the case of using a brushed motor with the same output.

[0008] The technical problem to be solved by the present invention is to provide a technology that helps to improve the inertia moment related to the impact energy in an impact tool using a brushless motor.

[0009] [Technical solutions for solving technical problems]

[0010] According to one embodiment of the present invention, an impact tool for driving a top tool is provided. The impact tool has a brushless motor and a cooling fan. The brushless motor has a rotating part including a rotor and a motor shaft, and drives the top tool by the rotational force of the rotating part. The cooling fan has a blade portion, and rotates by the rotational force of the rotating part. The cooling fan includes a resin component and a metal component. The metal component is at least arranged at a position that overlaps with the range of the diameter of the cooling fan on which the blade portion is arranged when viewed from the rotation axis direction of the cooling fan.

[0011] According to this method, a brushless motor is used to drive the top tool, so compared with a structure using a brushed motor, it is not necessary to replace the brush, and the motor can be made smaller and lighter, and the energy conversion efficiency can be improved. In addition, since the cooling fan includes a metal component, the inertia moment of the cooling fan can be increased compared with a cooling fan that does not include a metal component. Therefore, the inertia moment of the rotating part including the rotating component and the cooling fan can be increased. In addition, according to this method, the metal component is at least arranged at a position that overlaps with the range of the diameter of the cooling fan configured with the blade portion when viewed from the rotation axis direction of the cooling fan. Therefore, compared with a structure in which a metal component is only arranged on the periphery of the rotation axis of the cooling fan in order to improve the bonding strength with the motor shaft, this method can increase the inertia moment of the cooling fan. Therefore, the impact energy that can be output by the impact tool using a brushless motor can be increased. In this way, the impact tool of this method can obtain the advantages of using a brushless motor, and can output the required impact energy while suppressing the load current when driving the impact tool.

[0012] In one aspect of the present invention, the mass of the metal member may be 15% or more of the sum of the mass of the rotating member and the mass of the resin member of the cooling fan.

[0013] According to this method, by making the mass of the metal part more than 15% of the sum of the mass of the rotating part and the mass of the resin part of the cooling fan, the moment of inertia of the rotating part and the cooling fan of the impact tool driven by a brushless motor can be made the same as the moment of inertia of the rotor, motor shaft and cooling fan of the impact tool of the same size driven by a brushed motor.

[0014] In one aspect of the present invention, the cooling fan may be formed integrally with a resin member and a metal member.

[0015] According to this aspect, a cooling fan including resin components and metal components can be easily manufactured. In addition, since the cooling fan is integrally molded, it can have sufficient strength.

[0016] In one aspect of the present invention, the metal member may be disposed at least in a range outside one half of the radius of the cooling fan when viewed from the rotation axis direction of the cooling fan.

[0017] According to this aspect, the moment of inertia of the cooling fan can be increased compared to a structure in which a metal member of the same mass is arranged only at a position inside of half the radius of the cooling fan.

[0018] In one embodiment of the present invention, the cooling fan can be combined with the motor shaft. The portion of the cooling fan combined with the motor shaft can be formed by a metal component. Alternatively, the cooling fan and the motor shaft can be combined by pressing the motor shaft into a through hole provided on the cooling fan.

[0019] According to this aspect, the strength of the connection between the cooling fan and the motor shaft can be increased.

[0020] In one aspect of the present invention, the cooling fan may have a diameter of 80 mm or more.

[0021] According to this aspect, by increasing the diameter of the cooling fan, it is possible to increase the moment of inertia of the cooling fan.

[0022] In one aspect of the present invention, the cooling fan may have blades disposed on one side of the cooling fan in the direction of the rotation axis, and may have a metal member disposed on the other side of the cooling fan in the direction of the rotation axis.

[0023] According to this aspect, the structure of the cooling fan can be simplified.

[0024] In one aspect of the present invention, the cooling fan may have blades disposed on both surfaces in the rotation axis direction of the cooling fan, and may have a metal member disposed between the blades disposed on both surfaces.

[0025] According to this aspect, the air volume of the cooling fan can be increased, thereby improving the cooling efficiency.

[0026] In one embodiment of the present invention, the moment of inertia of the rotating part including the brushless motor and the rotating part of the cooling fan can be 1.6×10 -4 [kg·m 2 ]above.

[0027] The inventors know that for an impact tool having a brushless motor, a 1.6×10 -4 [kg·m 2 ]For impact tools with a moment of inertia of greater than 100 mm, it is particularly useful to include metal parts in the cooling fan to increase the moment of inertia.

[0028] Therefore, according to this method, it is possible to effectively increase the 1.6×10 -4 [kg·m 2 ]The above moment of inertia is the required moment of inertia of the impact tool.

[0029] In one aspect of the present invention, the impact energy that can be output may be 9.0 [J] or more.

[0030] The inventors have found that, for an impact tool having a brushless motor and requiring an impact energy of 9.0 [J] or more, including a metal member in the cooling fan to increase the moment of inertia is particularly useful for outputting the required impact energy.

[0031] Therefore, according to this aspect, since an impact energy of 9.0 [J] or more can be output, the effect of increasing the moment of inertia can be further exhibited by including a metal member in the cooling fan.

[0032] In one aspect of the present invention, the impact tool may be configured to perform processing on a workpiece by driving the tip tool in a linear manner. The tip tool may be driven in a direction that intersects with the rotation axis of the brushless motor.

[0033] According to this method, the driving direction of the tip tool intersects with the rotation axis of the brushless motor, so that the overall structure of the impact tool can be made compact. In particular, this method can be adopted in a large impact tool to efficiently achieve compactness while being able to output a large impact energy.

[0034] In one aspect of the present invention, a battery mounting portion configured to detachably mount a rechargeable battery may be provided. The brushless motor may be driven by power supplied from the battery mounted on the battery mounting portion.

[0035] As described above, by making the cooling fan include a metal component, the inertia moment can be efficiently increased, thereby reducing the load current for outputting the required impact energy. Therefore, according to this embodiment, the operating time of the impact tool driven by the power supplied by the battery can be extended. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a cross-sectional view of a hammer drill.

[0037] Figure 2 It is a perspective view of the cooling fan in the first embodiment.

[0038] Figure 3 It is a top view of the cooling fan in the first embodiment.

[0039] Figure 4 is with Figure 3 AA corresponds to the cross-sectional view.

[0040] Figure 5 This diagram shows the inertia moment and impact energy of various hammer drills and electric hammers.

[0041] Figure 6 This is an explanatory diagram showing the load current of a hammer drill.

[0042] Figure 7This is an explanatory diagram showing the load current of an electric hammer.

[0043] Figure 8 It is a perspective view of a cooling fan in the second embodiment.

[0044] Fig. 9 It is a top view of the cooling fan in the second embodiment.

[0045] Fig.10 is with Fig. 9 AA corresponds to the cross-sectional view.

[0046] Fig.11 is with Fig.10 The cross-sectional view corresponding to BB.

[0047] [Explanation of Reference Numerals]

[0048] 2: Motor; 3: Drive mechanism; 4: Mode switch dial; 5: Controller; 6: Lock mechanism; 7: Cooling fan; 8: Cooling fan; 10: Housing; 11: First housing; 13: Second housing; 14: Trigger; 15: Battery mounting portion; 18: Top tool; 19: Battery; 21: Stator; 23: Rotor; 25: Motor shaft; 26: Rotating member; 28: Drive gear; 30: Motion conversion mechanism; 34: Tool holder; 36: Impact structural element; 38: Rotation transmission mechanism; 39: Clutch; 40: Clutch switching mechanism; 41: Operation portion; 71: Through hole; 72: Blade part; 73: weight part; 74: coupling part; 81: through hole; 82a: upper blade part; 82b: lower blade part; 83: weight part; 84: coupling part; 101: hammer drill; 111: drive mechanism housing part; 117: motor housing part; 131: gripping part; 133: upper part; 137: lower part; 141: locking protrusion; 145: main switch; 171: elastic component; 175: elastic component; 731: through hole; A1: drive axis; A2: rotation axis; R: rotation axis; r1~r4: radius; HR1~HR7: hammer drill; HM2~HM10: electric hammer. DETAILED DESCRIPTION

[0049] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0050] [First embodiment]

[0051] Below, refer to Figure 1 to Figure 7The hammer drill 101 according to the first embodiment is described. The hammer drill 101 is an impact tool configured to be able to perform the following actions: an action of linearly driving a top tool 18 mounted on a tool holder 34 along a predetermined drive axis A1 (hereinafter referred to as a hammer action), and an action of rotating the top tool 18 around the drive axis A1 (hereinafter referred to as a drill action).

[0052] First, refer to Figure 1 , the schematic structure of the hammer drill 101 is described. Figure 1 As shown, the outer contour of the hammer drill 101 is mainly formed by the housing 10. The housing 10 of this embodiment is configured as a so-called vibration-proof housing, and includes a first housing 11 and a second housing 13 elastically connected to the first housing 11 so as to be relatively movable.

[0053] The first housing 11 is formed in a substantially L-shape as a whole and includes a motor housing portion 117 for housing the motor 2 and a drive mechanism housing portion 111 for housing the drive mechanism 3 configured to drive the top tool 18 by the power of the motor 2 .

[0054] The drive mechanism housing portion 111 is formed in an elongated shape and extends along the drive axis A1. A tool holder 34 capable of detaching and attaching the top tool 18 is arranged at one end in the long axis direction of the drive mechanism housing portion 111. The top tool 18 is driven along the direction of the drive axis A1 by the drive of the motor 2. The motor housing portion 117 is connected and fixed to the other end in the long axis direction of the drive mechanism housing portion 111. The motor housing portion 117 is arranged to intersect with the drive axis A1 and protrude from the drive mechanism housing portion 111 in a direction away from the drive axis A1. The motor 2 is arranged so that the rotation axis A2 of the motor shaft 25 is orthogonal to the drive axis A1. By making the driving direction of the top tool 18 (the direction of the drive axis A1) and the direction of the rotation axis A2 of the motor shaft 25 intersect, the hammer drill 101 as a whole is compactly constructed.

[0055] In the following description, for the sake of convenience, the extending direction of the drive axis A1 of the hammer drill 101 (the long axis direction of the drive mechanism housing portion 111) is defined as the front-to-back direction of the hammer drill 101. In the front-to-back direction, the side of one end portion where the tool holder 34 is provided is defined as the front side (also referred to as the top region side) of the hammer drill 101, and the side opposite to the one end portion where the tool holder 34 is provided is defined as the rear side. In addition, the extending direction of the rotation axis A2 of the motor shaft 25 is defined as the up-down direction of the hammer drill 101. In the up-down direction, the direction in which the motor housing portion 117 protrudes from the drive mechanism housing portion 111 is defined as the downward direction, and the direction opposite to the direction in which the motor housing portion 117 protrudes from the drive mechanism housing portion 111 is defined as the upward direction. Furthermore, the direction orthogonal to the front-to-back direction and the up-down direction is defined as the left-right direction.

[0056] The second housing 13 is a hollow body formed in a substantially U-shape as a whole, and includes a grip portion 131 , an upper portion 133 , and a lower portion 137 .

[0057] The grip portion 131 is a portion configured to be gripped by the user. The grip portion 131 is away from the first housing 11 toward the rear and extends in the up-down direction. A trigger 14 that can be pressed (pulled) by the user's finger is provided at the front of the grip portion 131. The upper portion 133 is a portion connected to the upper end of the grip portion 131. In the present embodiment, the upper portion 133 is configured to extend forward from the upper end of the grip portion 131 and cover most of the drive mechanism housing portion 111 of the first housing 11. The lower portion 137 is a portion connected to the lower end of the grip portion 131. In the present embodiment, the lower portion 137 extends forward from the lower end of the grip portion 131, and most of it is arranged on the lower side of the motor housing portion 117. A battery mounting portion 15 is provided at the lower end of the center portion in the front-back direction of the lower portion 137. The hammer drill 101 operates using a battery 19 that is detachably mounted on the battery mounting portion 15 as a power source.

[0058] With the above structure, in the hammer drill 101, in addition to the second housing 13, the motor housing 117 in the first housing 11 is exposed to the outside while being sandwiched from top to bottom by the upper portion 133 and the lower portion 137. The second housing 13 and the motor housing 117 form the outer surface of the hammer drill 101.

[0059] Next, the detailed structure of the hammer drill 101 will be described.

[0060] First, refer to Figure 1The vibration-proof structure of the housing 10 will be briefly described. As described above, in the housing 10 , the second housing 13 including the grip portion 131 is elastically connected to the first housing 11 accommodating the motor 2 and the drive mechanism 3 so as to be relatively movable.

[0061] In more detail, Figure 1 As shown, an elastic member 171 is sandwiched between the drive mechanism housing portion 111 of the first housing 11 and the upper portion 133 of the second housing 13. In addition, an elastic member 175 is sandwiched between the motor housing portion 117 of the first housing 11 and the lower portion 137 of the second housing 13. In addition, in the present embodiment, the elastic member 171 and the elastic member 175 are compression coil springs. The elastic member 171 and the elastic member 175 respectively apply forces to the first housing 11 and the second housing 13 in the extending direction of the drive axis A1 in the direction away from each other (the direction in which the gripping portion 131 is away from the first housing 11). That is, the first housing 11 and the second housing 13 are respectively applied forces to the front and rear.

[0062] Furthermore, the upper portion 133 is configured to be slidable relative to the upper end of the motor housing portion 117, and the lower portion 137 is configured to be slidable relative to the lower end of the motor housing portion 117. More specifically, the lower end surface of the upper portion 133 and the upper end surface of the motor housing portion 117 are slidable in a state of abutting each other. In addition, the upper end surface of the lower portion 137 and the lower end surface of the motor housing portion 117 are slidable in a state of abutting each other. Furthermore, although detailed illustrations are omitted, a sliding guide is provided near the elastic member 171 and the elastic member 175, and the sliding guide is used to guide the first housing 11 and the second housing 13 to move relative to each other in the front-rear direction.

[0063] By means of the vibration-proof structure as described above, the first housing 11 and the second housing 13 can move relative to each other in the front-rear direction. Therefore, the vibration in the extension direction (front-rear direction) of the drive axis A1, which is the largest and dominant one among the vibrations generated by the first housing 11 during the hammer action, can be effectively prevented from being transmitted to the second housing 13.

[0064] Next, the internal structure of the first housing 11 will be described.

[0065] like Figure 1As shown, the motor 2 is accommodated in the motor housing portion 117. In the present embodiment, the motor 2 adopts a brushless motor (brushless DC motor). The motor 2 has a stator 21, a rotor 23 and a motor shaft 25, wherein the motor shaft 25 extends from the rotor 23 in the direction of the rotation axis A2 (up and down direction). The upper and lower ends of the motor shaft 25 are rotatably supported by bearings. When the motor 2 is driven, the rotor 23 and the motor shaft 25 rotate as a whole. In the present embodiment, the rotor 23 and the motor shaft 25 are also collectively referred to as a rotating component 26. The upper end of the motor shaft 25 protrudes into the drive mechanism housing portion 111, and a drive gear 28 is formed at this portion.

[0066] In addition, a cooling fan 7 is coupled to the motor shaft 25. The coupling portion 27 on the motor shaft 25 coupled to the cooling fan 7 is knurled (roulette processing). The cooling fan 7 is coupled to the rotating member 26 by pressing the motor shaft 25 into a through hole 71 provided at the center of the radial direction of the cooling fan 7. When the motor 2 is driven, the rotating member 26 and the cooling fan 7 rotate integrally around the rotation axis A2. That is, the cooling fan 7 is rotated by the rotational force of the rotating member 26 (motor 2). As the cooling fan 7 rotates, the air entering from the air inlet (not shown) formed in the housing 10 mainly cools the controller 5 and the motor 2, and is discharged from the exhaust port (not shown). The details of the cooling fan 7 will be described later.

[0067] The drive mechanism 3 is accommodated in the drive mechanism accommodation portion 111. The drive mechanism 3 includes a motion conversion mechanism 30, an impact component 36, and a rotation transmission mechanism 38. The drive mechanism 3 having such a structure is a well-known mechanism, and thus will be briefly described below.

[0068] The motion conversion mechanism 30 is configured to convert the rotational motion of the motor shaft 25 into linear motion and transmit it to the impact structural element 36. In the present embodiment, a crank mechanism including a crank shaft and a piston is used as the motion conversion mechanism 30. When the motor 2 is driven and the piston moves forward, the impact structural element 36 transmits kinetic energy to the top tool 18 through the action of the air spring. Accordingly, the top tool 18 is driven linearly along the drive axis A1, thereby impacting the workpiece. On the other hand, when the piston moves backward, the impact structural element 36 and the top tool 18 return to their original positions. In this way, the hammer action is performed by the motion conversion mechanism 30 and the impact structural element 36.

[0069] The rotation transmission mechanism 38 is configured to transmit the rotational power of the motor shaft 25 to the tool holder 34. In the present embodiment, the rotation transmission mechanism 38 is configured as a gear reduction mechanism including a plurality of gears. A meshing clutch 39 is arranged on the power transmission path of the rotation transmission mechanism 38. When the clutch 39 is in an engaged state, the tool holder 34 rotates through the rotation transmission mechanism 38, thereby driving the top tool 18 mounted on the tool holder 34 to rotate around the drive axis A1. On the other hand, when the clutch 39 is released from the engaged state ( Figure 1 denoting a disengaged state), the power transmission from the rotation transmission mechanism 38 to the tool holder 34 is cut off, so that the tip tool 18 is not driven to rotate.

[0070] In the present embodiment, the hammer drill 101 is configured to operate in one of two modes, a hammer mode and a hammer drill mode. The hammer mode is a mode in which the clutch 39 is in a disengaged state and only the motion conversion mechanism 30 is driven to perform only the hammer operation. The hammer drill mode is a mode in which the clutch 39 is in an engaged state and the motion conversion mechanism 30 and the rotation transmission mechanism 38 are driven to perform both the hammer operation and the drill operation.

[0071] The hammer drill 101 has a mode switching dial 4 for the user to select a mode. The mode switching dial 4 is supported at the upper rear end of the first housing 11 (specifically, the drive mechanism housing portion 111) in a manner that allows rotation around a rotation axis R extending in the up-down direction. In addition, the upper rear end of the drive mechanism housing portion 111 is covered by the upper portion 133 of the second housing 13, but the disc-shaped operating portion 41 of the mode switching dial 4 is exposed to the outside of the second housing 13 through an opening provided in the upper portion 133.

[0072] The mode switching dial 4 is provided with switching positions corresponding to the hammer mode and the hammer drill mode along the circumferential direction around the rotation axis R. Although detailed illustration is omitted, marks corresponding to the respective switching positions are marked on the upper portion 133. The user can select the mode by rotating the operating portion 41 so that the pointer of the operating portion 41 is aligned with the switching position (one of the two marks) corresponding to the desired mode. In addition, the switching positions corresponding to the hammer mode and the hammer drill mode are referred to as the hammer position and the hammer drill position, respectively, hereinafter.

[0073] like Figure 1As shown, a clutch switching mechanism 40 is provided in the drive mechanism housing portion 111. The clutch switching mechanism 40 is connected to the mode switching dial 4 and is configured to switch the clutch 39 between an engaged state and a disengaged state. When the mode switching dial 4 is switched to the hammer position (i.e., when the hammer mode is selected), the clutch switching mechanism 40 puts the clutch 39 in a disengaged state. On the other hand, when the mode switching dial 4 is switched to the hammer drill position (i.e., when the hammer drill mode is selected), the clutch switching mechanism 40 puts the clutch 39 in an engaged state. In addition, since the structure of the above-mentioned clutch switching mechanism 40 is a well-known technology, detailed description and illustration are omitted here.

[0074] Next, the internal structure of the second housing 13 will be described.

[0075] First, the internal structure of the upper portion 133 will be described. Figure 1 As shown, the lock mechanism 6 is disposed in the rear portion of the upper portion 133. The lock mechanism 6 is a mechanism configured to restrict movement of the trigger 14 according to the switch position of the mode switch dial 4 (ie, the mode selected by the user).

[0076] Next, the internal structure of the gripping portion 131 will be described. Figure 1 As shown, the gripping portion 131 is configured as a cylindrical portion extending in the up-down direction. A trigger 14 that can be pressed (pulled) by the user is provided at the front portion of the gripping portion 131. The trigger 14 is configured to be able to rotate approximately in the front-to-back direction within a specified rotation range, with a rotation axis extending in the left-right direction as the center. The trigger 14 is always forced forward and is maintained at the frontmost position within the rotation range in a non-pressed state. In addition, the trigger 14 is forced by the plunger (and / or force spring) of the main switch 145. The trigger 14 can rotate to the rearmost position in response to the user's pressing operation. A locking protrusion 141 protruding upward is provided at the upper end portion of the trigger 14. In the present embodiment, the two locking protrusions 141 are separated and arranged in the left-right direction.

[0077] A main switch 145 is provided inside the grip 131. The main switch 145 switches between an on state and an off state in response to the operation of the trigger 14. Specifically, the main switch 145 is maintained in an off state when the trigger 14 is in a non-pressed state configured at the frontmost position. On the other hand, when the trigger 14 is pressed and reaches a prescribed working position within the rotation range, the main switch 145 is in an on state. In addition, although the illustration is omitted, in the present embodiment, the rearmost position of the trigger 14 is set to a position slightly behind the working position. The main switch 145 is in an off state when the trigger 14 is located between the frontmost position and the working position (excluding the working position) within the rotation range, and is in an on state when it is located between the working position and the rearmost position (including the working position). Hereinafter, the position of the trigger 14 when the main switch 145 is in an off state is referred to as an off position, and the position of the trigger 14 when the main switch 145 is in an on state is referred to as an on position.

[0078] Next, the internal structure of the lower portion 137 will be described. Figure 1 As shown, the lower portion 137 is formed in a rectangular box shape with a partially open upper side, and is arranged on the lower side of the motor housing portion 117 .

[0079] A controller 5 is disposed inside the lower portion 137. Although detailed illustrations are omitted, the controller 5 includes a control circuit, a substrate on which the control circuit is mounted, and a housing for accommodating these components. In addition, in the present embodiment, the control circuit is configured as a microcomputer including a CPU, a ROM, a RAM, and the like. The controller 5 (control circuit) is electrically connected to the motor 2, the main switch 145, the battery mounting portion 15, and the like through wires not shown. In the present embodiment, the controller 5 (control circuit) is configured so that when the trigger 14 is pressed and the main switch 145 becomes in the on state, power is started to be supplied to the motor 2 (i.e., the top tool 18 is driven), and when the pressing operation of the trigger 14 is released and the main switch 145 becomes in the off state, power is stopped to the motor 2.

[0080] In addition, as described above, the battery mounting portion 15 is provided on the lower portion 137. In the present embodiment, two battery mounting portions 15 are provided side by side in the front-rear direction. That is, two batteries 19 can be installed in the hammer drill 101. In the present embodiment, the battery 19 is a rechargeable battery. The battery mounting portion 15 has a snap-fit ​​structure that can be slidably engaged with the battery 19 and a terminal that can be electrically connected to the battery 19. Since the structure of such a battery mounting portion 15 is well known, detailed illustration and description are omitted.

[0081] As described above, the hammer drill 101 is configured such that when the motor 2 is driven, the motion conversion mechanism 30 converts the rotational motion of the motor shaft 25 into linear motion and transmits it to the impact structural element 36. Then, the impact structural element 36 transmits the kinetic energy to the top tool 18. The top tool 18 outputs the transmitted kinetic energy to the workpiece as impact energy. That is, in the hammer drill 101, the kinetic energy of the motor 2 is converted into impact energy and output.

[0082] In the hammer drill 101, when the motor 2 is driven, the rotor 23, the motor shaft 25, and the cooling fan 7 rotate. That is, the kinetic energy of the rotating rotor 23, the motor shaft 25, and the cooling fan 7 is converted into impact energy and output. The kinetic energy of an object that rotates is proportional to the inertia moment of the rotating object and the square of the angular velocity. Therefore, in this embodiment, by increasing the inertia moment of the cooling fan 7 that rotates, it is possible to suppress the increase in load current while improving the impact energy output by the hammer drill 101. Next, the cooling fan 7 of the hammer drill 101 will be described.

[0083] use Figure 2 to Figure 4 , the structure of the cooling fan 7 is described.

[0084] like Figure 2 As shown, the cooling fan 7 has a blade portion 72 and a weight portion 73. The blade portion 72 is formed on the lower surface of the cooling fan 7. The weight portion 73 is arranged on the upper surface of the cooling fan 7. The blade portion 72 is molded by a resin component. The weight portion 73 is composed of a metal component. In the present embodiment, the cooling fan 7 is formed by integrally molding (insert molding) a resin component and a metal component. In other words, the cooling fan 7 is formed by integrally molding a resin component and a metal component by casting. Such a structure of a cooling fan is suitable for a structure in which the weight portion 73 is arranged on one side and the blade portion 72 is arranged on the other side, so that the structure can be simplified and the manufacturing can be simplified.

[0085] In addition, the peripheral portion of the insertion hole 71 provided in the cooling fan 7 is formed by a metal member. In other words, the coupling portion 74 of the cooling fan 7 coupled to the rotating member 26 (motor shaft 25) is formed by a metal member. In addition, as described above, the cooling fan 7 is coupled to the rotating member 26 by pressing the motor shaft 25 into the insertion hole 71 provided at the center in the radial direction of the cooling fan 7. Therefore, the strength of coupling between the cooling fan 7 and the motor shaft 25 can be improved.

[0086] The weight portion 73 has a through hole 731. When the metal component and the resin component are insert-molded, the resin component is filled inside the through hole 731. The through hole 731 of the metal component and the resin component filled inside the through hole 731 function as a fall-off prevention component (anchor).

[0087] like Figure 3 and Figure 4 As shown, with the rotation axis A2 as the center in the radial direction of the cooling fan 7, the blade portion 72 is arranged in the range from radius r2 to radius r4 in the radial direction of the cooling fan 7. In addition, the weight portion 73 is arranged in the range from radius r1 to radius r3 in the radial direction of the cooling fan 7. When viewed from the direction of the rotation axis A2 (up and down direction), the range from radius r1 to radius r3 overlaps with the range from radius r2 to radius r4. That is, when viewed from the direction of the rotation axis A2 (up and down direction), the weight portion 73, which is a metal component, is at least arranged at a position that overlaps with the range of the diameter of the cooling fan 7 on which the blade portion 72 is arranged. By applying this structure, the moment of inertia of the cooling fan 7 can be increased.

[0088] Furthermore, when viewed from the direction of the rotation axis A2, the weight portion 73, which is a metal component, is disposed at least in a range outside half of the radius (r4) of the cooling fan 7. Therefore, compared with a structure in which the weight portion 73 of the same mass is disposed only in a range inside half of the radius of the cooling fan 7, the inertia moment of the cooling fan 7 can be increased.

[0089] In the present embodiment, a cooling fan 7 having a diameter of 80 mm or more is used. More specifically, the diameter of the cooling fan 7 applicable to the present embodiment is 90 mm. By making the diameter of the cooling fan 7 larger, the inertia moment of the cooling fan 7 can be further increased.

[0090] In addition, in the present embodiment, the mass of the weight portion 73 (metal component) included in the cooling fan 7 is 15% or more of the sum of the mass of the rotating component 26 including the rotor 23 and the motor shaft 25 and the mass of the resin component included in the cooling fan 7. The reason for applying such a method will be described later.

[0091] In this embodiment, the inertia moment of the rotating parts including the rotating member 26 of the motor 2 (including the rotor 23 and the motor shaft 25) and the cooling fan 7 is 1.6×10-4 [kg·m 2 The reason for applying such a method will be described later.

[0092] In the present embodiment, the cooling fan 7 having such a configuration is applied to a relatively large hammer drill 101 that can output an impact energy of 9.0 [J] or more in the hammer mode. The reason for applying such a method will be described later.

[0093] Next, the effect of including a weight portion (metal member) in the cooling fan will be described.

[0094] Figure 5 This is a table showing the results of calculating the inertia moment of the rotating parts (rotor, motor shaft, cooling fan) of a hammer drill and an electric hammer, which are a type of impact tool. Figure 5 The upper part represents the moment of inertia of the rotating parts of the hammer drill. Figure 5 The lower part of represents the inertia moment of the rotating parts of the electric hammer. Figure 5 The inertia moment of the rotating parts of the hammer drill shown in the upper part represents the inertia moment in the hammer mode.

[0095] Figure 5 The left side of the indicates a smaller model, and the right side indicates a larger model. For example, Figure 5 Among the multiple hammer drills shown in FIG. 1 , hammer drill HR1 is the smallest hammer drill, and hammer drill HR7 is the largest hammer drill. Figure 5 Among the multiple electric hammers shown, the electric hammer HM2 is the smallest electric hammer, and the electric hammer HM10 is the largest electric hammer. Figure 5 The hammer drill shown corresponds to HR7.

[0096] exist Figure 5 In the table shown, when the hammer drill and electric hammer are shown in the upper and lower corresponding positions, the corresponding machine models represent the hammer drill and electric hammer of the same size. Figure 5 In the table, hammer drill HR3 and electric hammer HM3 represent hammer drills and electric hammers of the same size.

[0097] Figure 5 The "Motor" column indicates the type of motor used in the model. Brushed motors are marked with "BR" (brush motor) and brushless motors are marked with "BL" (brushless motor). Figure 5 In the diagram, when two adjacent models are shown, the model on the left indicates a model using a brushed motor (BR), and the model on the right indicates a model using a brushless motor (BL). For example, a brushed motor is used in the hammer drill HR2, and a brushless motor is used in the electric hammer HM3. These two models are models of the same size. As another example, the electric hammer HM4 and the electric hammer HM5 are models of the same size. A brushed motor (BR) is used in the electric hammer HM4, and a brushless motor (BL) is used in the electric hammer HM5.

[0098] In this embodiment, the model using a brushed motor (BR) uses a brushed motor of the most suitable size for the model. On the other hand, the model using a brushless motor (BL) uses two sizes of brushless motors. Specifically, a brushless motor "BLtype1" and a brushless motor "BLtype2" are used. The two brushless motors are different in size. The length of the rotor of the brushless motor BLtype2 in the direction of the rotation axis A2 (the total length of the magnet of the rotor) is twice the length of the rotor of the brushless motor BLtype1. The diameters of the two brushless motors are the same.

[0099] Figure 5 The "Weight Part" column indicates whether the cooling fan includes a weight part. Specifically, if the cooling fan includes a weight part (metal part), it is displayed as "included", and if the cooling fan does not include a weight part (metal part), it is displayed as "not included".

[0100] Figure 5 The "Moment of Inertia" column shows the value of the moment of inertia of the rotor, motor shaft and cooling fan. Figure 5 As shown, the values ​​of the inertia moment are calculated using the brushless motor BLtype1 in the hammer drill HR3 and the electric hammer HM3. Therefore, the values ​​of the inertia moment indicated in the columns of the hammer drill HR3 and the electric hammer HM3 represent the values ​​of the inertia moment of the rotor and motor shaft of the brushless motor BLtype1 and the cooling fan.

[0101] The values ​​of the moment of inertia in two styles are calculated in the hammer drill HR5 and the electric hammer HM5. The value of the moment of inertia is calculated as one style using the brushless motor BLtype1. The value of the moment of inertia is calculated as another style using the brushless motor BLtype2. The value of the moment of inertia of the style using the brushless motor BLtype2 is calculated only when the cooling fan does not include a weight part (metal part). The reason for this will be described later.

[0102] The value of the moment of inertia is calculated using the brushless motor BLtype2 used in the hammer drill HR7, rotary hammer HM7, and rotary hammer HM9.

[0103] Figure 5 The "Impact Energy" column is the value of the impact energy found for each model, and is the value of the impact energy that can be output confirmed through actual measurement.

[0104] Figure 5 The "Fan Diameter" column shows the diameter of the cooling fan used in each model.

[0105] Figure 5The "Fan Mass" column shows the mass of the cooling fan used in each model. The value in parentheses shows the mass of the weight part (metal part) included in the cooling fan. For example, when the cooling fan of the hammer drill HR7 includes a weight part, the mass of the entire cooling fan including the resin part and the metal part (weight part) is 140.3 [g]. In addition, the mass of the metal part (weight part) included in the cooling fan of the hammer drill HR7 alone is 101.5 [g].

[0106] Figure 5 The "Mass of rotating parts" column shows the mass of the rotating parts (rotor, motor shaft) used in each model.

[0107] Next, the results of comparing the inertia moment of a model using a brushed motor (BR) and the inertia moment of a model using a brushless motor (BL) will be described.

[0108] As per Figure 5 As can be seen, in the model where the value of the required impact energy is lower than 9.0 [J], there is not much difference in the mass of the rotating parts between the model using a brushed motor and the model using a brushless motor. That is, there is not much difference between the mass of the rotating parts of the hammer drill HR2 and the mass of the rotating parts of the hammer drill HR3. In addition, there is not much difference between the mass of the rotating parts of the electric hammer HM2 and the mass of the rotating parts of the electric hammer HM3. Therefore, even if the cooling fan of the model using a brushless motor does not include a weight part (metal parts), there is not much difference in the moment of inertia between the model using a brushed motor and the model using a brushless motor. In other words, even if the mass of the cooling fan of the model using a brushless motor is not increased, there is not much difference in the moment of inertia between the model using a brushed motor and the model using a brushless motor. As a result, the load current when the required impact energy is output can be made roughly the same between the corresponding models (the model using a brushed motor and the model using a brushless motor).

[0109] On the other hand, Figure 5 As shown, in the models with a required impact energy value of 9.0 [J] or more, there is a large difference in the mass of the rotating parts between the models using a brushed motor and the models using a brushless motor.

[0110] For example, the mass of the rotating parts of the hammer drill HR4 is 684 [g]. On the other hand, the mass of the rotating parts of the hammer drill HR5 is 346 [g] when the brushless motor BLtype1 is used, which is significantly different from the mass of the rotating parts of the hammer drill HR4. In the case where the cooling fan of the hammer drill HR5 does not include a weight portion, there is a significant difference between the moment of inertia of the hammer drill HR5 and the moment of inertia of the hammer drill HR4. The moment of inertia of the hammer drill HR5 is much smaller than that of the hammer drill HR4.

[0111] When the cooling fan of the hammer drill HR5 using the brushless motor BLtype1 includes a weight portion, the moment of inertia of the hammer drill HR5 and the moment of inertia of the hammer drill HR4 are close in value. Therefore, for the hammer drill HR5 using the brushless motor BLtype1, including a weight portion in the cooling fan is useful for outputting the required impact energy. In addition, the same reason as that of the hammer drill HR4 and the hammer drill HR5 can also be applied to the electric hammer HM4 and the electric hammer HM5.

[0112] In the case where the brushless motor BLtype2 is used in the hammer drill HR5, the mass of the rotating parts is 524 [g], which is not much different from the mass of the rotating parts of the hammer drill HR4. Therefore, in this case, it is not necessary to include a weight portion in the cooling fan. The reason for this is that in the model where the brushless motor BLtype2 is used in the hammer drill HR5, only the moment of inertia when the weight portion is not included in the cooling fan is calculated.

[0113] As another example, the mass of the rotating part of the hammer drill HR6 is 920 [g]. On the other hand, the mass of the rotating part of the hammer drill HR7 is 524 [g] when the brushless motor BLtype2 is used, which is significantly different from the mass of the rotating part of the hammer drill HR6.

[0114] The impact energy required for hammer drills HR6 and HR7 is greater than that for hammer drills HR4 and HR5. That is, the output required of the motor is greater. For a brushed motor (BR), the greater the required output, the greater the size and mass of the rotor. This is because the rotor of the brushed motor (BR) is composed of coils. In the brushed motor (BR), the coil of the rotor is enlarged to increase the output. Therefore, the mass of the rotating parts of the brushed motor (BR) used in the hammer drill HR6 is greater than that of the brushed motor (BR) used in the hammer drill HR4.

[0115] On the other hand, for the brushless motor (BL), even if the required motor output increases, the rotor size and mass do not increase because the rotor is composed of permanent magnets. That is, when the required motor output increases, the increase rate of the size and mass of the rotating parts of the brushless motor (BL) is smaller than the increase rate of the size and mass of the rotating parts of the brushed motor (BR).

[0116] For such reasons, even if the brushless motor BLtype2 is used in the hammer drill HR7, there is a large mass difference between the mass of the rotating parts of the hammer drill HR7 and the mass of the rotating parts of the hammer drill HR6. As a result, when the cooling fan of the hammer drill HR7 does not include a weight portion, there is a large moment difference between the moment of inertia of the hammer drill HR7 and the moment of inertia of the hammer drill HR6. The moment of inertia of the hammer drill HR7 is much smaller than the moment of inertia of the hammer drill HR6.

[0117] On the other hand, when the cooling fan of the hammer drill HR7 includes a weight portion, the moment of inertia of the hammer drill HR7 and the moment of inertia of the hammer drill HR6 are close in value. Therefore, it is useful for the hammer drill HR7 to include a weight portion in the cooling fan. The same reason can also be applied to the electric hammers HM6, HM7, HM8, and HM9.

[0118] As described above, for an impact tool having a brushless motor (BL) that requires an impact energy of 9.0 [J] or more, it is particularly useful to include a weight portion (metal component) in the cooling fan to increase the moment of inertia in order to output the required impact energy.

[0119] In addition, by making the cooling fan of the model using the brushless motor (BL) include a weight portion and making the inertia moment the most suitable value for the model, it is possible to reduce the load current during the machining operation while outputting the required impact energy. As a result, the operating time of the battery-driven impact tool can be extended.

[0120] Next, use Figure 6 and Figure 7 The following technology is presented: by including a weight portion in the cooling fan of a model using a brushless motor, the inertia moment of the rotating parts (rotor, motor shaft, cooling fan) is made to be the most optimal value, thereby reducing the load current.

[0121] Figure 6 The measured values ​​of the load current when the cooling fan of the hammer drill HR7 includes a weight portion and when the cooling fan of the hammer drill HR7 does not include a weight portion are shown. In addition, in this measurement, the hammer drill HR7 is driven in the hammer mode. In addition, Figure 7 The measured values ​​of the load current are shown when the cooling fan of hammer HM7 includes a weight portion and when the cooling fan of hammer HM7 does not include a weight portion. Figure 6 and Figure 7 Any measured value in is the value of the load current when the machining operation is performed while outputting the required impact energy. Figure 6 and Figure 7The pressing load on the workpiece during measurement is the same for any measured value in the measurement. In the load current measurement including the weight portion in the cooling fan, the load current value of each moment of inertia is measured by using the values ​​of three moments of inertia by adjusting the mass of the weight portion. This measurement is performed by installing two top tools (top tools A and B) on the hammer drill HR7 and the electric hammer HM7 to measure the load current value in each top tool.

[0122] According to the above measurement results, it can be seen that when the cooling fan includes a weight portion, there is a value of inertia moment that reduces the load current value compared to when the cooling fan does not include a weight portion. In the measurement of hammer drill HR7, among the values ​​of the three moments of inertia and all the top tools (top tools A and B), the case where the cooling fan includes a weight portion can reduce the load current value more than the case where it does not include a weight portion. In the measurement of electric hammer HM7, among the values ​​of the three moments of inertia and all the top tools (top tools A and B), the case where the cooling fan includes a weight portion can reduce the load current value more than the case where it does not include a weight portion. Moreover, in the measurement of hammer drill HR7 and the measurement of electric hammer HM7, there is a value of inertia moment that minimizes the load current value when the cooling fan includes a weight portion. Specifically, in the measurement of hammer drill HR7, by making the cooling fan include a weight portion and making the moment of inertia 2.5×10-4[kg·m 2 ], the load current value can be minimized. In the measurement of the electric hammer HM7, the cooling fan is made to include a weight portion and the inertia moment is made 2.4×10-4 [kg·m 2 ], the load current value can be minimized. That is, when the cooling fan includes a weight portion and the inertia moment is adjusted, there is an optimum inertia moment value that can minimize the load current value. In the impact tool, by adjusting the mass of the weight portion included in the cooling fan to achieve the optimum inertia moment that can minimize the load current value, the load power value when processing the workpiece can be effectively reduced.

[0123] Therefore, by making the cooling fan of the model using a brushless motor include a weight portion and making the inertia moment the most suitable value, it is possible to reduce the load current while maintaining the required impact energy output. Figure 5 As described in , for a model using a brushless motor with a required impact energy value of 9.0 [J] or more, including a weight portion in the cooling fan is particularly effective in reducing the load current.

[0124] In addition, if Figure 5 As shown in the figure, it can be understood that for the model using a brushless motor, 1.6×10-4 [kg·m 2] or above, it is particularly useful to include a weight portion (metal component) in the cooling fan to increase the moment of inertia. In other words, for a machine requiring 1.6×10-4[kg·m 2 ], if the cooling fan does not include the weight part (metal parts), there will be a large difference in inertia between the models of the same size using brushed motors. Therefore, in models with brushless motors, the inertia required is 1.6×10-4[kg·m 2 In models with a moment of inertia of 1000 mm or more, it is particularly effective to include a weight portion (metal component) in the cooling fan in order to increase the moment of inertia while suppressing the increase in load current.

[0125] In addition, if Figure 5 As shown, when the mass of the weight part (metal part) included in the cooling fan is more than 15% of the sum of the mass of the rotating part and the mass of the resin part of the cooling fan, the inertia moment of the rotating part and the cooling fan of the impact tool (hammer drill, electric hammer) driven by the brushless motor can be made the same as the inertia moment of the rotor, motor shaft and cooling fan of the impact tool (hammer drill, electric hammer) of the same size driven by the brush motor. For example, in the electric hammer HM5, the mass of the cooling fan is 114.6 [g]. The mass of the weight part of the cooling fan is 74.5 [g]. Therefore, the mass of the resin part of the cooling fan is 40.1 [g] (114.6-74.5). The sum of the mass (346 [g]) of the rotating part (BLtype1) and the mass (40.1 [g]) of the resin part of the cooling fan is 386.1 [g] (346+40.1). The mass (74.5 [g]) of the heavy portion (metal parts) included in the cooling fan is 15% or more of the sum of the mass of the rotating parts and the mass of the resin parts of the cooling fan (386.1 [g]).

[0126] In addition, if Figure 5 As shown in the figure, the model using a brushless motor with a required impact energy value of 9.0 [J] or more adopts a cooling fan with a diameter of 80 mm or more. When the cooling fan has a large diameter and contains a weight part, the moment of inertia can be increased efficiently. That is, for a model of this size, the diameter of the cooling fan is set to 80 mm or more, which can effectively increase the moment of inertia while maintaining high cooling efficiency.

[0127] As described above, the hammer drill 101 in this embodiment uses a brushless motor as the motor 2 to drive the top tool 18, so the advantages of using a brushless motor can be obtained. For example, compared with a structure using a brushed motor, the hammer drill 101 in this embodiment can eliminate the need to replace the brushes, and the motor 2 can be made smaller and lighter, and the energy conversion efficiency can be improved. In addition, in this embodiment, the cooling fan 7 includes the weight portion 73 (metal component), so the inertia moment of the cooling fan 7 can be increased compared with a cooling fan that does not include a metal component. Therefore, the inertia moment of the rotating part including the rotating component (rotor 23, motor shaft 25) and the cooling fan 7 can be increased. In addition, the metal component is at least arranged at a position that overlaps with the range of the diameter of the cooling fan 7 where the blade portion 72 is arranged when viewed from the rotation axis direction of the cooling fan 7. Therefore, compared with a structure in which a metal component is arranged only on the periphery of the rotation axis of the cooling fan in order to improve the bonding strength with the motor shaft, the inertia moment of the cooling fan 7 can be increased. Therefore, the impact energy that can be output by the hammer drill 101 can be increased. In this way, the hammer drill 101 of the present embodiment can obtain the advantage of using a brushless motor and can output required impact energy while suppressing the load current when the hammer drill 101 is driven.

[0128] In addition, since the resin member and the metal member are integrally molded, the cooling fan 7 can be easily manufactured. In addition, since the cooling fan 7 is integrally molded, it can have sufficient strength.

[0129] Furthermore, the portion of the cooling fan 7 that is coupled to the motor shaft 25 is formed of a metal component (weight portion 73), and the cooling fan 7 is coupled to the motor shaft 25 by pressing the motor shaft 25 into a through hole 71 provided on the cooling fan 7, thereby improving the strength of the coupling between the cooling fan 7 and the motor shaft 25.

[0130] When viewed from the direction of the rotation axis A2 of the cooling fan 7, the weight portion 73 (metal component) is at least arranged in a range outside half of the radius of the cooling fan 7. Therefore, compared with a structure in which the weight portion (metal component) of the same mass is only arranged in a position inside half of the radius of the cooling fan, the inertia moment of the cooling fan 7 can be increased.

[0131] In addition, since the mass of the weight portion 73 (metal component) is more than 15% of the sum of the mass of the rotating component 26 and the mass of the resin component of the cooling fan 7, the moment of inertia of the rotating component 26 and the cooling fan 7 can be made the same as the moment of inertia of the rotor, motor shaft and cooling fan of an impact tool of the same size driven by a brushed motor.

[0132] Since the hammer drill 101 of the present embodiment includes the cooling fan 7 having a diameter of 80 mm or more, it is possible to increase the moment of inertia of the cooling fan 7 while maintaining high cooling efficiency.

[0133] Furthermore, since the cooling fan 7 has the blade portion 72 disposed on one surface in the direction of the rotation axis A2 and a weight portion (metal member) disposed on the other surface, the structure can be simplified.

[0134] The above description shows that, for an impact tool having a brushless motor and requiring a moment of inertia of 1.6×10-4 [kg·m2] or more, it is particularly useful to increase the moment of inertia by including a metal component in the cooling fan. Therefore, in the hammer drill 101 of the present embodiment, since the moment of inertia of the rotating part including the rotating component 26 of the brushless motor (motor 2) and the cooling fan 7 is 1.6×10-4 [kg·m2] or more, the moment of inertia can be effectively increased by including the weight portion 73 in the cooling fan 7.

[0135] In addition, the above description shows that, for an impact tool having a brushless motor and requiring an impact energy of 9.0 [J] or more, it is particularly useful to increase the moment of inertia by including a metal component in the cooling fan for outputting the required impact energy. Since the hammer drill 101 in the present embodiment can output an impact energy of 9.0 [J] or more, the effect of increasing the moment of inertia by including a weight portion 73 (metal component) in the cooling fan 7 can be further exerted.

[0136] In addition, as described above, by including the weight portion 73 (metal component) in the cooling fan 7, the inertia moment can be efficiently increased, and thus the load power for outputting the required impact energy can be reduced. The hammer drill 101 of this embodiment has a battery mounting portion 15 configured as a removable rechargeable battery 19, and the motor 2 (brushless motor) is driven by the power supplied by the battery 19 mounted on the battery mounting portion 15. Therefore, by including the weight portion 73 in the cooling fan 7, the operating time of the hammer drill 101 driven by the power supplied by the battery 19 can be extended.

[0137] In the hammer drill 101 of the present embodiment, since the driving direction of the tip tool 18 intersects with the rotation axis A2 of the motor 2 (brushless motor), the size of the hammer drill 101 can be made compact.

[0138] [Second embodiment]

[0139] The second embodiment is different from the first embodiment described above in the structure of the cooling fan.

[0140] use Figure 8 to Figure 11 , the cooling fan 8 in the second embodiment will be described.

[0141] The cooling fan 8 is provided with blade portions on both sides (upper and lower sides) in the direction of the rotation axis A2. Specifically, the cooling fan 8 has an upper blade portion 82a and a lower blade portion 82b. The upper blade portion 82a and the lower blade portion 82b are molded by resin components. In addition, the cooling fan 8 has a weight portion 83 of a metal component between the upper blade portion 82a and the lower blade portion 82b. In the present embodiment, the cooling fan 8 is formed by integrally molding the resin component and the metal component (insert molding). Therefore, it is possible to achieve simplification of manufacturing.

[0142] In addition, similarly to the first embodiment, the peripheral portion of the insertion hole 81 provided in the cooling fan 8 is formed by a metal component. In other words, the coupling portion 84 of the cooling fan 8 coupled to the rotating member 26 (motor shaft 25) is formed by a metal component. In addition, the cooling fan 8 is coupled to the rotating member 26 by pressing the motor shaft 25 into the insertion hole 81 provided at the center in the radial direction of the cooling fan 8. Therefore, since the motor shaft 25 is pressed into the insertion hole 81 of the metal component of the cooling fan 8, the strength of the coupling between the cooling fan 8 and the motor shaft 25 can be improved.

[0143] In addition, similar to the first embodiment, when viewed from the direction of the rotation axis A2 (up and down direction), the weight portion 83 as a metal component is at least arranged at a position overlapping with the range of the diameter of the cooling fan 8 where the upper blade portion 82a and the lower blade portion 82b are arranged. By applying such a structure, the inertia moment of the cooling fan 8 can be increased.

[0144] Furthermore, when viewed from the direction of the rotation axis A2, the weight portion 83, which is a metal member, is disposed at least outside half the radius of the cooling fan 8. Therefore, the moment of inertia of the cooling fan 8 can be further increased.

[0145] In addition, in the present embodiment, the cooling fan 8 having a diameter of 80 mm or more is adopted. Therefore, the inertia moment of the cooling fan 8 can be increased.

[0146] Furthermore, in the present embodiment, the mass of the weight portion 83 (metal component) included in the cooling fan 8 is 15% or more of the sum of the mass of the rotating component 26 including the rotor 23 and the motor shaft 25 and the mass of the resin components included in the cooling fan 8 .

[0147] In the present embodiment, the moment of inertia of the rotating parts including the rotating member 26 (including the rotor 23 and the motor shaft 25) of the motor 2 and the cooling fan 8 is 1.6×10-4 [kg·m2] or more. In addition, in the present embodiment, the cooling fan 8 of such a structure is applied to a relatively large hammer drill 101 that can output an impact energy of 9.0 [J] or more in the hammer mode.

[0148] As described above, the hammer drill 101 in this embodiment includes the cooling fan 8. Since the cooling fan 8 is provided with blade portions (upper blade portion 82a, lower blade portion 82b) on both sides in the direction of the rotation axis A2, the air volume of the cooling fan can be increased, thereby improving the cooling efficiency. In addition, as in the above-mentioned first embodiment, since the cooling fan 8 includes the weight portion 83, the same effect as the above-mentioned first embodiment can be obtained. That is, the inertia moment of the cooling fan 8 can be increased, and the impact energy can be improved while suppressing the load power.

[0149] The following shows the correspondence between the various components of the above-mentioned embodiment and the various components of the present invention. However, the various components of the above-mentioned embodiment are only examples and do not limit the various components of the present invention. Figure 5 The hammer drill and electric hammer shown are examples of "impact tools" of the present invention. Figure 6 , Figure 7 The top tools A and B shown in the figure are examples of "top tools" of the present invention. The cooling fan 7 and the cooling fan 8 are examples of "cooling fans" of the present invention. The rotating component 26 including the rotor 23 and the motor shaft 25 is an example of a "rotating component" of the present invention. The weight portion 73 and the weight portion 83 are examples of "metal components" of the present invention. The structure composed of the rotating component 26 (rotor 23, motor shaft 25) and the cooling fan 7 is an example of a "rotating part" of the present invention. The battery mounting portion 15 is an example of a "battery mounting portion" of the present invention. The battery 19 is an example of a "battery" of the present invention.

[0150] The above-mentioned embodiment is only an example, and the impact tool involved in the present invention is not limited to a hammer drill and an electric hammer which are impact tools that drive the top tool linearly along the drive shaft. Other impact tools can be used as long as the top tool is driven by the rotational force of the rotor and the motor shaft that are rotated by the brushless motor and the impact tool has a cooling fan that is rotated by the rotational force.

[0151] In the above embodiment, the cooling fan 7 and the cooling fan 8 are structures directly connected to the motor shaft 25, but other structures may also be used. The cooling fan may also be connected to the motor shaft 25 through gears or other connecting parts. That is, a structure may also be used in which the rotational force of the motor shaft 25 is transmitted to the cooling fan through gears or other connecting parts, thereby rotating the cooling fan. The use of such a structure can also increase the inertia moment related to the impact energy output by the impact tool when the cooling fan includes a weight portion (metal component), thereby being able to obtain the same effect as the above embodiment.

[0152] In the above-described embodiment, various metal members such as iron, copper, silver, lead, tin, stainless steel, brass, aluminum, tungsten, or alloys containing these can be used as the metal member used for the weight portion.

[0153] In the above embodiment, when viewed from the direction of the rotation axis of the cooling fan, the weight portion (metal component) is a structure arranged from a position closer to the inside than one-half of the radius of the cooling fan to a position closer to the outside than one-half of the radius of the cooling fan, but a structure in which the weight portion is only arranged at a position closer to the outside than one-half of the radius of the cooling fan may also be adopted.

[0154] In addition, a part of the blade portion of the cooling fan may be formed of a metal component. In addition, a weight portion may be arranged on the pressure surface or negative pressure surface of the blade portion of the cooling fan. A weight portion may be arranged separately in multiple areas of the cooling fan.

[0155] Furthermore, the following aspects are constructed in view of the gist of the present invention and the above-described embodiments and their modifications. The following aspects can be adopted in combination with the configurations described in the embodiments.

[0156] [Method 1]

[0157] The mass of the metal member (weight portion) included in the cooling fan is set so that the load current value becomes minimum when the impact tool is driven so that the pressing load on the workpiece becomes a constant value.

[0158] [Method 2]

[0159] The inertia moment of the rotating member including the brushless motor and the rotating part of the cooling fan is set so that the load current value becomes minimum when the impact tool is driven so that the pressing load on the workpiece becomes a constant value.

Claims

1. An impact tool for driving a top tool, characterized in that: With brushless motor and cooling fan, The brushless motor has a rotating part including a rotor and a motor shaft, and drives the top tool by a rotational force of the rotating part; The cooling fan is coupled to the motor shaft in the housing of the impact tool, has a blade portion, and is rotated by the rotational force of the rotating member to cool at least the brushless motor. The cooling fan includes a resin component and a metal component. The metal member is arranged at least at a position overlapping with a range of a diameter of the cooling fan where the blade portion is arranged when viewed from the rotation axis direction of the cooling fan. The impact energy that the impact tool can output is 9.0J or more. The moment of inertia of the rotating part including the brushless motor and the rotating part of the cooling fan is 1.6×10-4kg·m2 or more, The mass of the metal member is 15% or more of the sum of the mass of the rotating member and the mass of the resin member of the cooling fan.

2. The impact tool according to claim 1, characterized in that The resin member and the metal member of the cooling fan are integrally molded.

3. The impact tool according to claim 1 or 2, characterized in that: The metal member is disposed at least in a range outside one half of the radius of the cooling fan when viewed in the rotation axis direction of the cooling fan.

4. The impact tool according to claim 1 or 2, characterized in that: The cooling fan is combined with the motor shaft, The portion of the cooling fan coupled to the motor shaft is formed by the metal component. The cooling fan is coupled to the motor shaft by press-fitting the motor shaft into a through hole provided on the cooling fan.

5. The impact tool according to claim 1 or 2, characterized in that: The diameter of the cooling fan is greater than 80 mm.

6. The impact tool according to claim 1 or 2, characterized in that: The cooling fan has the blade portion disposed on one surface in the rotation axis direction of the cooling fan, and has the metal member disposed on the other surface in the rotation axis direction of the cooling fan.

7. The impact tool according to claim 1 or 2, characterized in that: The cooling fan has the blade portions arranged on both surfaces in the rotation axis direction of the cooling fan, and the metal member is arranged between the blade portions arranged on the both surfaces.

8. The impact tool according to claim 1 or 2, characterized in that: The impact tool is configured to perform processing on a workpiece by driving the tip tool in a linear manner. The driving direction of the top tool intersects with the rotation axis of the brushless motor.

9. The impact tool according to claim 1 or 2, characterized in that: A battery installation portion configured to be a removable rechargeable battery is provided, The brushless motor is driven by electric power supplied from the battery mounted on the battery mounting portion.

Images