Impact tools

Abstract

To provide a technology that contributes to improvement of inertia moment related to impact energy in an impact tool using a brushless motor.SOLUTION: A hammer drill 101 includes a cooling fan 7 which has a blade part 72 and is rotated by rotational force of a rotary member 26. The cooling fan 7 includes a resin member and a metallic member (a weight 73). The metallic member is disposed at a position overlapping with at least a range of a diameter of the cooling fan 7, where the blade part 72 is disposed, when viewed in a rotation axis A2 direction of the cooling fan 7.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an impact tool that drives a tool bit. [Background technology]

[0002] It is known that brushless motors are used as motors mounted on power tools. By using a brushless motor in a power tool, for example, the following advantages can be obtained. Compared to a commutator motor (hereinafter also referred to as a brush motor), a brushless motor can eliminate the need for brush replacement. In addition, the motor itself can be made smaller and lighter, and energy conversion efficiency can be improved. For example, Patent Document 1 listed below discloses an impact tool using a brushless motor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-79557 A Summary of the Invention [Problem to be solved by the invention]

[0004] An impact tool processes a workpiece by converting the rotational force of a motor into impact energy. The magnitude of the impact energy output from an impact tool depends on the moment of inertia of the motor. Due to its structure, a brushless motor has a smaller moment of inertia of rotating members including a rotor and a motor shaft compared to a brush motor of the same output. Therefore, when a brushless motor is used for an impact tool, the load current for outputting the required impact energy becomes larger than when a brush motor of the same output is used.

[0005] An object of the present invention is to provide a technique that contributes to improving the moment of inertia, which is related to impact energy, in an impact tool using a brushless motor. [Means for solving the problem]

[0006] According to one aspect of the present invention, there is provided an impact tool for driving a tool tip. The impact tool includes a brushless motor and a cooling fan. The brushless motor has a rotating member including a rotor and a motor shaft, and drives the tool tip by the rotational force of the rotating member. The cooling fan has a blade portion and rotates by the rotational force of the rotating member. The cooling fan includes a resin member and a metal member. The metal member is arranged at a position overlapping at least the radial range of the cooling fan in which the blade portion is arranged, when viewed from the direction of the rotation axis of the cooling fan.

[0007] According to this aspect, since a brushless motor is used to drive the tool bit, compared to a configuration using a brush motor, brush replacement is not necessary, 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 member, the moment of inertia of the cooling fan can be made larger compared to a cooling fan that does not include a metal member. Therefore, the moment of inertia of the rotating part including the rotating member and the cooling fan can be made larger. In addition, according to this aspect, the metal member is arranged at a position that overlaps at least the range of the diameter of the cooling fan in which the blade portion is arranged when viewed from the direction of the rotation axis of the cooling fan. Therefore, this aspect can increase the moment of inertia of the cooling fan compared to a configuration in which the metal member is arranged only on the periphery of the rotation axis of the cooling fan to increase the coupling strength with the motor shaft. Therefore, the impact energy that can be output by an impact tool using a brushless motor can be improved. In this way, the impact tool of this aspect can obtain the advantages of using a brushless motor, and can output the required impact energy while suppressing the load current when the impact tool is driven.

[0008] 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.

[0009] According to this embodiment, by making the mass of the metal member 15% or more of the sum of the mass of the rotating member and the mass of the plastic member of the cooling fan, the moment of inertia of the rotating member and cooling fan of an impact tool driven by a brushless motor can be made equivalent to the moment of inertia of the rotor, motor shaft and cooling fan of an impact tool of an equivalent size driven by a brush motor.

[0010] In one aspect of the present invention, the cooling fan may be formed by integrally molding a resin member and a metal member.

[0011] According to this aspect, the cooling fan including the resin member and the metal member can be easily manufactured. Moreover, since the cooling fan is molded as a single unit, it can have sufficient strength.

[0012] In one aspect of the present invention, the metal member may be disposed in a range at least outside half the radius of the cooling fan when viewed from the direction of the rotation axis of the cooling fan.

[0013] According to this embodiment, the moment of inertia of the cooling fan can be increased, compared to a configuration in which metal members of the same mass are arranged only inside half the radius of the cooling fan.

[0014] In one aspect of the present invention, the cooling fan may be coupled to the motor shaft. A portion of the cooling fan coupled to the motor shaft may be formed of a metal member. The cooling fan may be coupled to the motor shaft by press-fitting the motor shaft into an insertion hole provided in the cooling fan.

[0015] According to this aspect, the strength of the connection between the cooling fan and the motor shaft can be increased.

[0016] In one embodiment of the present invention, the cooling fan may have a diameter of 80 mm or more.

[0017] According to this aspect, the diameter of the cooling fan is made relatively large, so that the moment of inertia of the cooling fan can be increased.

[0018] In one aspect of the present invention, the cooling fan may have blades disposed on one surface of the cooling fan in the direction of a rotation axis, and a metal member disposed on the other surface of the cooling fan in the direction of the rotation axis.

[0019] According to this aspect, the structure of the cooling fan can be simplified.

[0020] In one aspect of the present invention, the cooling fan may have blades arranged on both sides in a direction of a rotation axis of the cooling fan, and a metal member may be arranged between the blades arranged on both sides.

[0021] According to this aspect, the amount of air blown by the cooling fan can be increased, and the cooling efficiency can be improved.

[0022] In one embodiment of the present invention, the moment of inertia of the rotating part including the rotating member and the cooling fan of the brushless motor is 1.6×10 -4 [kg m 2 ] or more.

[0023] Among impact tools equipped with brushless motors, 1.6 x 10 -4 [kg m 2 The inventors have found that for impact tools of a size requiring a moment of inertia of 100 mm or more, incorporating a metal member in the cooling fan is particularly useful for increasing the moment of inertia. Therefore, according to this embodiment, 1.6×10 -4 [kg m 2 It is possible to effectively increase the moment of inertia of an impact tool which requires a moment of inertia of at least 100 mm.

[0024] In one aspect of the present invention, the outputtable impact energy may be 9.0 [J] or more.

[0025] The inventors have discovered that for impact tools equipped with brushless motors that require an impact energy of 9.0 [J] or more, incorporating a metal component in the cooling fan to increase the moment of inertia is particularly useful for outputting the required impact energy. Therefore, according to this embodiment, it is possible to output an impact energy of 9.0 [J] or more, so that the effect of increasing the moment of inertia by including a metal member in the cooling fan can be further enhanced.

[0026] In one aspect of the present invention, the impact tool may be configured to perform a machining operation on a workpiece by linearly driving the tool bit. The driving direction of the tool bit and the rotation axis of the brushless motor may intersect.

[0027] According to this aspect, the driving direction of the bit and the rotation axis of the brushless motor intersect, so that the impact tool as a whole can be made compact. By adopting this aspect to a large impact tool in particular, it is possible to efficiently make the tool compact while still enabling the output of large impact energy.

[0028] In one aspect of the present invention, a battery mounting section configured to allow a rechargeable battery to be attached and detached may be provided, and the brushless motor may be driven by power supplied from a battery attached to the battery mounting section.

[0029] As described above, since the cooling fan includes a metal member, the moment of inertia is efficiently improved, and therefore the load current for outputting the required impact energy can be reduced, and therefore, according to this aspect, the runtime of the impact tool driven by the power supplied from the battery can be extended. [Brief description of the drawings]

[0030] [Figure 1] FIG. [Diagram 2]FIG. 2 is a perspective view of the cooling fan according to the first embodiment. [Diagram 3] FIG. 2 is a top view of the cooling fan in the first embodiment. [Figure 4] 4 is a cross-sectional view corresponding to the line AA in FIG. 3. [Diagram 5] FIG. 1 is an explanatory diagram showing the moment of inertia and impact energy of a plurality of types of hammer drills and hammers. [Figure 6] FIG. 4 is an explanatory diagram showing a load current of a hammer drill. [Figure 7] FIG. 4 is an explanatory diagram showing a load current of a hammer. [Figure 8] FIG. 11 is a perspective view of a cooling fan according to a second embodiment. [Figure 9] FIG. 11 is a top view of a cooling fan according to a second embodiment. [Figure 10] 10 is a cross-sectional view corresponding to the line AA in FIG. 9. [Figure 11] 11 is a cross-sectional view corresponding to the line BB in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0032] [First embodiment] A hammer drill 101 according to a first embodiment will be described below with reference to Fig. 1 to Fig. 7. The hammer drill 101 is an impact tool configured to be capable of performing an operation of linearly driving the tip tool 18 attached to a tool holder 34 along a predetermined drive axis A1 (hereinafter referred to as a hammering operation) and an operation of rotationally driving the tip tool 18 around the drive axis A1 (hereinafter referred to as a drilling operation).

[0033] First, the schematic configuration of a hammer drill 101 will be described with reference to Fig. 1. As shown in Fig. 1, the outer shell of the hammer drill 101 is mainly formed by a housing 10. The housing 10 in 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 movable relative to the first housing 11.

[0034] The first housing 11 is generally formed in a substantially L-shape. The first housing 11 includes a motor accommodating portion 117 that accommodates the motor 2, and a drive mechanism accommodating portion 111 that accommodates the drive mechanism 3 that is configured to drive the tool bit 18 by the power of the motor 2.

[0035] The drive mechanism housing 111 is formed in an elongated shape and extends along the drive axis A1. A tool holder 34 to which the tool bit 18 can be detachably attached is disposed at one end of the drive mechanism housing 111 in the longitudinal direction. The tool bit 18 is driven in the drive axis A1 direction by the motor 2. The motor housing 117 is fixedly connected to the other end of the drive mechanism housing 111 in the longitudinal direction. The motor housing 117 is disposed so as to intersect the drive axis A1 and protrude from the drive mechanism housing 111 in a direction away from the drive axis A1. The motor 2 is disposed so that the rotation axis A2 of the motor shaft 25 is perpendicular to the drive axis A1. The direction in which the tool bit 18 is driven (the drive axis A1 direction) and the direction of the rotation axis A2 of the motor shaft 25 intersect, so that the entire hammer drill 101 is configured compactly.

[0036] In the following description, for convenience, the extending direction of the drive shaft A1 of the hammer drill 101 (the longitudinal direction of the drive mechanism housing 111) is defined as the front-rear direction of the hammer drill 101. In the front-rear direction, one end side where the tool holder 34 is provided is defined as the front side (also referred to as the tip area side) of the hammer drill 101, and the opposite side 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 117 protrudes from the drive mechanism housing 111 is defined as the downward direction, and the opposite direction is defined as the upward direction. Furthermore, the direction perpendicular to the front-rear direction and the up-down direction is defined as the left-right direction.

[0037] The second housing 13 is a hollow body formed in a generally U-shape as a whole, and includes a grip portion 131, an upper portion 133, and a lower portion 137.

[0038] The grip portion 131 is a portion configured to be gripped by a user. The grip portion 131 is spaced rearward from the first housing 11 and extends in the up-down direction. A trigger 14 that can be pressed (pulled) by a user with a 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 this 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 accommodating 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 this embodiment, the lower portion 137 extends forward from the lower end of the grip portion 131 and most of it is disposed below the motor accommodating portion 117. A battery mounting portion 15 is provided at the lower end of the center of the lower portion 137 in the front-rear direction. The hammer drill 101 operates using a battery 19 that is removably mounted in the battery mounting portion 15 as a power source.

[0039] With the above-described configuration, in the hammer drill 101, in addition to the second housing 13, the motor accommodating portion 117 of the first housing 11 is exposed to the outside while being sandwiched from above and below between the upper portion 133 and the lower portion 137. The second housing 13 and the motor accommodating portion 117 form the outer surface of the hammer drill 101.

[0040] Next, the detailed configuration of the hammer drill 101 will be described.

[0041] First, the vibration-proof structure of the housing 10 will be briefly described with reference to Fig. 1. As described above, in the housing 10, the second housing 13 including the grip portion 131 is elastically connected to the first housing 11 that houses the motor 2 and the drive mechanism 3 so as to be movable relative to the first housing 11.

[0042] More specifically, as shown in FIG. 1, an elastic member 171 is interposed between the drive mechanism accommodating portion 111 of the first housing 11 and the upper portion 133 of the second housing 13. Furthermore, an elastic member 175 is interposed between the motor accommodating portion 117 of the first housing 11 and the lower portion 137 of the second housing 13. In this embodiment, a compression coil spring is used for the elastic members 171 and 175. The elastic members 171 and 175 respectively bias the first housing 11 and the second housing 13 in a direction away from each other (a direction in which the grip portion 131 moves away from the first housing 11) in the extending direction of the drive shaft A1. That is, the first housing 11 and the second housing 13 are respectively biased forward and backward.

[0043] Furthermore, the upper portion 133 and the lower portion 137 are configured to be slidable relative to the upper end and lower end of the motor accommodating portion 117, respectively. More specifically, the lower end surface of the upper portion 133 and the upper end surface of the motor accommodating portion 117 are slidable in abutting contact with each other. Also, the upper end surface of the lower portion 137 and the lower end surface of the motor accommodating portion 117 are slidable in abutting contact with each other. Furthermore, although not shown in detail, a sliding guide is provided near the elastic member 171 and the elastic member 175 to guide the relative movement of the first housing 11 and the second housing 13 in the front-rear direction.

[0044] The vibration-proof structure described above allows relative movement in the front-rear direction between the first housing 11 and the second housing 13. Therefore, it is possible to effectively prevent the transmission of the largest and most dominant vibration generated in the first housing 11 during hammering operation in the direction in which the drive shaft A1 extends (front-rear direction) to the second housing 13.

[0045] Next, the internal structure of the first housing 11 will be described.

[0046] As shown in FIG. 1, the motor 2 is accommodated in the motor accommodating section 117. In this embodiment, a brushless motor (brushless DC motor) is adopted as the motor 2. The motor 2 includes a stator 21, a rotor 23, and a motor shaft 25 extending from the rotor 23 in the direction of the rotation axis A2 (up and down direction). The motor shaft 25 is rotatably supported by bearings at the upper and lower ends. When the motor 2 is driven, the rotor 23 and the motor shaft 25 rotate integrally. In this embodiment, the rotor 23 and the motor shaft 25 are collectively referred to as a rotating member 26. The upper end of the motor shaft 25 protrudes into the drive mechanism accommodating section 111, and a drive gear 28 is formed on this portion.

[0047] A cooling fan 7 is coupled to the motor shaft 25. A coupling portion 27 of the motor shaft 25 with the cooling fan 7 is knurled. The motor shaft 25 is press-fitted into an insertion hole 71 provided at the radial center of the cooling fan 7, whereby the cooling fan 7 is coupled to the rotating member 26. When the motor 2 is driven, the rotating member 26 and the cooling fan 7 rotate integrally about the rotation axis A2. That is, the cooling fan 7 rotates due to the rotational force of the rotating member 26 (motor 2). Air sucked in from an intake port (not shown) formed in the housing 10 by the rotation of the cooling fan 7 mainly cools the controller 5 and the motor 2, and is discharged from an exhaust port (not shown). The cooling fan 7 will be described in detail later.

[0048] The drive mechanism accommodating portion 111 accommodates the drive mechanism 3. The drive mechanism 3 includes a motion conversion mechanism 30, an impact element 36, and a rotation transmission mechanism 38. Note that the drive mechanism 3 having such a configuration is well known, and therefore will be described briefly below.

[0049] 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 striking element 36. In this embodiment, a crank mechanism including a crankshaft and a piston is used as the motion conversion mechanism 30. When the motor 2 is driven and the piston moves forward, the striking element 36 transmits kinetic energy to the tool tip 18 due to the action of the air spring. As a result, the tool tip 18 is driven linearly along the drive axis A1 and strikes the workpiece. On the other hand, when the piston moves backward, the striking element 36 and the tool tip 18 return to their original positions. In this manner, the hammering action is performed by the motion conversion mechanism 30 and the striking element 36.

[0050] The rotation transmission mechanism 38 is configured to transmit the rotational power of the motor shaft 25 to the tool holder 34. In this embodiment, the rotation transmission mechanism 38 is configured as a gear reduction mechanism including a plurality of gears. A meshing clutch 39 is disposed on the power transmission path of the rotation transmission mechanism 38. When the clutch 39 is in an engaged state, the tool holder 34 is rotated by the rotation transmission mechanism 38, and the tool tip 18 attached to the tool holder 34 is rotationally driven about the drive shaft A1. On the other hand, when the clutch 39 is disengaged (FIG. 1 shows the disengaged state), the power transmission by the rotation transmission mechanism 38 to the tool holder 34 is interrupted, and the tool tip 18 is not rotationally driven.

[0051] In this embodiment, the hammer drill 101 is configured to operate according to a selected one of two modes, a hammer mode and a hammer drill mode. The hammer mode is a mode in which only the hammering action is performed by disengaging the clutch 39 and driving only the motion conversion mechanism 30. The hammer drill mode is a mode in which the clutch 39 is engaged and driving the motion conversion mechanism 30 and the rotation transmission mechanism 38, thereby performing both the hammering action and the drilling action.

[0052] The hammer drill 101 includes a mode dial 4 that allows a user to select a mode. The mode dial 4 is supported on an upper rear end portion of the first housing 11 (more specifically, the drive mechanism accommodating portion 111) so as to be rotatable about a rotation axis R extending in the vertical direction. The upper rear end portion of the drive mechanism accommodating portion 111 is covered by an upper portion 133 of the second housing 13, but the disk-shaped operating portion 41 of the mode dial 4 is exposed to the outside of the second housing 13 through an opening provided in the upper portion 133.

[0053] The mode switching dial 4 has switching positions set in the circumferential direction around the rotation axis R, which respectively correspond to the hammer mode and the hammer drill mode. Although detailed illustration is omitted, marks corresponding to each switching position are printed on the upper portion 133. The user can select a mode by rotating the operation unit 41 and aligning a pointer on the operation unit 41 with a switching position (one of two marks) corresponding to the desired mode. In the following, the switching positions corresponding to the hammer mode and the hammer drill mode, respectively, are referred to as the hammer position and the hammer drill position.

[0054] As shown in FIG. 1, the drive mechanism accommodating section 111 includes a clutch switching mechanism 40 connected to the mode switching dial 4 and 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 disengages the clutch 39. 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 engages the clutch 39. Note that the configuration of the clutch switching mechanism 40 is a well-known technique, and therefore detailed description and illustration thereof will be omitted here.

[0055] Next, the internal structure of the second housing 13 will be described.

[0056] First, a description will be given of the internal structure of the upper portion 133. As shown in Fig. 1, a lock mechanism 6 is disposed inside the rear portion of the upper portion 133. The lock mechanism 6 is a mechanism configured to restrict the movement of the trigger 14 according to the switching position of the mode switching dial 4 (i.e., the mode selected by the user).

[0057] Next, the internal structure of the grip portion 131 will be described. As shown in FIG. 1, the grip portion 131 is configured as a cylindrical portion extending in the vertical direction. The front portion of the grip portion 131 is provided with a trigger 14 that can be pressed (pulled) by the user. The trigger 14 is configured to be rotatable in the approximately front-rear direction within a predetermined rotation range around a rotation axis extending in the left-right direction. The trigger 14 is always biased forward, and is held at the frontmost position in the rotation range in a non-pressed state. The trigger 14 is biased by a plunger (and / or a biasing spring) of the main switch 145. The trigger 14 can be rotated to the rearmost position in response to a pressing operation by the user. An engagement protrusion 141 that protrudes upward is provided at the upper end of the trigger 14. In this embodiment, two engagement protrusions 141 are arranged spaced apart from each other on the left and right.

[0058] A main switch 145 is provided inside the grip portion 131. The main switch 145 is switched 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 in a non-pressed state in which the trigger 14 is disposed at the most forward position. On the other hand, when the trigger 14 is pressed and reaches a predetermined actuation position within the rotation range, the main switch 145 is turned on. Although not shown in the drawings, in this embodiment, the rearmost position of the trigger 14 is set slightly rearward of this actuation position. The main switch 145 is turned off when the trigger 14 is between the most forward position and the actuation position (excluding the actuation position) within the rotation range, and is turned on when the trigger 14 is between the actuation position and the rearmost position (including the actuation position). Hereinafter, the position of the trigger 14 that turns the main switch 145 off is referred to as the off position, and the position of the trigger 14 that turns the main switch 145 on is referred to as the on position.

[0059] Next, a description will be given of the internal structure of the lower portion 137. As shown in Fig. 1, the lower portion 137 is formed in a rectangular box shape with a part of the upper side open, and is disposed below the motor accommodating portion 117.

[0060] The controller 5 is disposed inside the lower portion 137. Although detailed illustration is omitted, the controller 5 includes a control circuit, a board on which the control circuit is mounted, and a case that houses them. In this 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 section 15, and the like by electric wires (not shown). In this embodiment, the controller 5 (control circuit) is configured to start energizing the motor 2 (i.e., driving the tip tool 18) when the trigger 14 is pressed and the main switch 145 is turned on, and to stop energizing the motor 2 when the trigger 14 is released and the main switch 145 is turned off.

[0061] As described above, the lower portion 137 is provided with a battery mounting section 15. In this embodiment, two battery mounting sections 15 are arranged side by side in the front-rear direction. That is, two batteries 19 can be mounted on the hammer drill 101. In this embodiment, the batteries 19 are rechargeable batteries. The battery mounting section 15 has an engagement structure that can slidably engage with the battery 19, and terminals that can be electrically connected to the battery 19. The configuration of such a battery mounting section 15 is well known, so detailed illustration and description will be omitted.

[0062] As described above, the hammer drill 101 is configured such that, when the motor 2 is driven, the motion converting mechanism 30 converts the rotational motion of the motor shaft 25 into linear motion and transmits it to the striking element 36. The striking element 36 then transmits kinetic energy to the tool tip 18. The tool tip 18 outputs the transmitted kinetic energy to the workpiece as striking energy. That is, in the hammer drill 101, the kinetic energy of the motor 2 is converted into striking energy and output.

[0063] In the hammer drill 101, when the motor 2 is driven, the rotor 23, the motor shaft 25, and the cooling fan 7 perform rotational motion. 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 performing rotational motion is proportional to the moment of inertia and the square of the angular velocity of the rotating object. Therefore, in this embodiment, the moment of inertia of the rotating cooling fan 7 is increased to suppress an increase in the load current, thereby improving the impact energy output by the hammer drill 101. The cooling fan 7 provided in the hammer drill 101 will be described below.

[0064] The structure of the cooling fan 7 will be described with reference to FIGS.

[0065] As shown in FIG. 2, the cooling fan 7 includes a blade portion 72 and a weight 73. The blade portion 72 is formed on the lower surface of the cooling fan 7. The weight 73 is disposed on the upper surface of the cooling fan 7. The blade portion 72 is molded from a resin member. The weight 73 is composed of a metal member. In this embodiment, the cooling fan 7 is formed by integrally molding (insert molding) a resin member and a metal member. In other words, the cooling fan 7 is formed by integrally molding a resin member and a metal member by casting. By applying a structure in which the weight 73 is disposed on one side and the blade portion 72 is disposed on the other side as the structure of the cooling fan, it is possible to simplify the structure and the manufacturing process.

[0066] Also, the peripheral portion of the insertion hole 71 provided in the cooling fan 7 is formed of a metal member. In other words, the coupling portion 74 of the cooling fan 7 with the rotating member 26 (motor shaft 25) is formed of a metal member. As described above, the motor shaft 25 is press-fitted into the insertion hole 71 provided in the radial center of the cooling fan 7, whereby the cooling fan 7 is coupled to the rotating member 26. This makes it possible to increase the strength of the coupling between the cooling fan 7 and the motor shaft 25.

[0067] A through hole 731 is formed in the weight 73. When the metal member and the resin member are insert-molded, the resin member is filled inside the through hole 731. The through hole 731 of the metal member and the resin member filled inside the through hole 731 function as a retainer (anchor).

[0068] As shown in FIG. 3 and FIG. 4, when the rotation axis A2 is set as the center of the radial direction of the cooling fan 7, the blade portion 72 is arranged in the range of radius r2 to radius r4 in the radial direction of the cooling fan 7. The weight 73 is arranged in the range of radius r1 to radius r3 in the radial direction of the cooling fan 7. When viewed from the direction of the rotation axis A2 (vertical direction), the range of radius r1 to radius r3 overlaps with the range of radius r2 to radius r4. In other words, the weight 73, which is a metal member, is arranged at a position that overlaps at least the radial range of the cooling fan 7 in which the blade portion 72 is arranged, when viewed from the direction of the rotation axis A2 (vertical direction). By applying such a configuration, the moment of inertia of the cooling fan 7 can be increased.

[0069] Furthermore, when viewed from the direction of rotation axis A2, weight 73, which is a metal member, is disposed in a range at least outside half the radius (r4) of cooling fan 7. Therefore, the moment of inertia of cooling fan 7 can be made larger than in a configuration in which weight 73 of the same mass is disposed only in a range inside half the radius of cooling fan 7.

[0070] In this embodiment, the cooling fan 7 has a diameter of 80 mm or more. More specifically, the diameter of the cooling fan 7 applied to this embodiment is 90 mm. By making the diameter of the cooling fan 7 relatively large, the moment of inertia of the cooling fan 7 can be further increased.

[0071] In addition, in this embodiment, the mass of weight 73 (metal member) included in cooling fan 7 is 15% or more of the sum of the mass of rotating member 26 including rotor 23 and motor shaft 25 and the mass of the resin member included in cooling fan 7. The reason for applying such a mode will be described later.

[0072] Furthermore, in this embodiment, the moment of inertia of the rotating part 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 2The reason for applying such an embodiment will be described later.

[0073] In this embodiment, the cooling fan 7 having such a configuration is applied to a relatively large hammer drill 101 that can output impact energy of 9.0 [J] or more in the hammer mode. The reason for applying such an embodiment will be described later.

[0074] The effect of incorporating a weight (metallic member) in the cooling fan will be described below.

[0075] Fig. 5 is a table showing the results of calculating the moment of inertia of the rotating members (rotor, motor shaft, cooling fan) of a hammer drill and a hammer, which are types of impact tools. The upper part of Fig. 5 shows the moment of inertia of the rotating members of the hammer drill. The lower part of Fig. 5 shows the moment of inertia of the rotating members of the hammer. Note that the moment of inertia of the rotating members of the hammer drill shown in the upper part of Fig. 5 shows the moment of inertia in hammer mode.

[0076] In Fig. 5, the left side shows a model of a smaller size, and the right side shows a model of a larger size. For example, of the multiple hammer drills shown in Fig. 5, the hammer drill HR1 is the smallest size hammer drill, and the hammer drill HR7 is the largest size hammer drill. Also, of the multiple hammers shown in Fig. 5, the hammer HM2 is the smallest size hammer drill, and the hammer HM10 is the largest size hammer drill. The hammer drill 101 in this embodiment corresponds to the hammer drill HR7 shown in Fig. 5.

[0077] In the table shown in Fig. 5, when corresponding hammer drills and hammers are shown above and below, the corresponding models indicate hammer drills and hammers of the same size. For example, in Fig. 5, the hammer drill HR3 and the hammer HM3 indicate hammer drills and hammers of the same size.

[0078] The "Motor" column in FIG. 5 indicates the type of motor used in that model. Brush motors are indicated as "BR" (brush motor), and brushless motors are indicated as "BL" (brushless motor). In FIG. 5, when two models are shown adjacent to each other, the model on the left indicates a model in which a brush motor (BR) is used, and the model on the right indicates a model in which a brushless motor (BL) is used. For example, a brush motor is used in the hammer drill HR2, and a brushless motor is used in the hammer HM3. These two models are of the same size. As another example, the hammer HM4 and hammer HM5 are models of the same size. A brush motor (BR) is used in the hammer HM4, and a brushless motor (BL) is used in the hammer HM5.

[0079] In this experimental example, for models that use a brush motor (BR), a brush motor of an optimal size for that model is used. On the other hand, for models that use a brushless motor (BL), two sizes of brushless motors are used. Specifically, a brushless motor "BLtype1" and a brushless motor "BLtype2" are used. These two types of brushless motors are different in size. The length of the rotor of the brushless motor BLtype2 in the direction of the rotation axis A2 (total length of the magnet in the rotor) is twice the length of the rotor of the brushless motor BLtype1. The diameters of these two types of brushless motors are the same.

[0080] The "Weight" column in Figure 5 indicates whether or not the cooling fan includes a weight. Specifically, if the cooling fan includes a weight (metallic member), it is marked as "included," and if the cooling fan does not include a weight (metallic member), it is marked as "not included."

[0081] The "Moment of Inertia" column in Fig. 5 shows the values ​​of the moment of inertia of the rotor, motor shaft, and cooling fan. As shown in Fig. 5, for the hammer drill HR3 and hammer HM3, the values ​​of the moment of inertia were calculated using the brushless motor BLtype1. Therefore, the values ​​of the moment of inertia shown in the columns for the hammer drill HR3 and hammer HM3 show the values ​​of the moment of inertia of the rotor and motor shaft of the brushless motor BLtype1, and the cooling fan.

[0082] For the hammer drill HR5 and hammer HM5, the moment of inertia values ​​were calculated in two patterns. In one pattern, the brushless motor BL type 1 was used to calculate the moment of inertia value. In the other pattern, the brushless motor BL type 2 was used to calculate the moment of inertia value. The moment of inertia value for the pattern using the brushless motor BL type 2 was calculated only when the cooling fan did not include a weight (metallic member). The reason for this will be explained later.

[0083] The moment of inertia values ​​were calculated using the brushless motor BL type 2 for the hammer drill HR7, hammer HM7, and hammer HM9.

[0084] The "Impact Energy" column in FIG. 5 shows the impact energy value required for each model, and also shows the impact energy value that has been confirmed as being possible to output through actual measurement.

[0085] The "Fan diameter" column in Figure 5 shows the diameter of the cooling fan used in each model.

[0086] The "Fan mass" column in Figure 5 shows the mass of the cooling fan used in each model. The value in parentheses shows the mass of the weight (metallic component) included in the cooling fan. For example, in the case of the Hammer Drill HR7, where the cooling fan includes a weight, the mass of the entire cooling fan, including the plastic and metallic components (weight), is 140.3 g. And the mass of just the metallic component (weight) included in the cooling fan of the Hammer Drill HR7 is 101.5 g.

[0087] The column "Mass of Rotating Members" in Figure 5 shows the mass of the rotating members (rotor, motor shaft) used in each model.

[0088] Below we will describe the results of a comparison of the moment of inertia of models that use brush motors (BR) and models that use brushless motors (BL).

[0089] As can be seen from FIG. 5, in models with a required impact energy value of less than 9.0 [J], there is no significant difference in the mass of the rotating members between models using brush motors and models using brushless motors. That is, there is no significant difference in the mass of the rotating members of the hammer drill HR2 and the hammer drill HR3. Also, there is no significant difference in the mass of the rotating members of the hammer HM2 and the hammer HM3. Therefore, even if the cooling fan of the model using a brushless motor does not include a weight (metal member), there is no significant difference in the moment of inertia between models using brush motors and models using brushless motors. In other words, even if the mass of the cooling fan of the model using a brushless motor is not increased, there is no significant difference in the moment of inertia between models using brush motors and models using brushless motors. As a result, the load current when outputting the required impact energy can be made approximately equal between the corresponding models (models using brush motors and models using brushless motors).

[0090] On the other hand, as shown in FIG. 5, for models with required impact energy values ​​of 9.0 [J] or more, there is a large difference in the mass of the rotating members between models using brush motors and models using brushless motors.

[0091] For example, the mass of the rotating members of the hammer drill HR4 is 684 [g]. On the other hand, the mass of the rotating members of the hammer drill HR5 is 346 [g] when the brushless motor BL type 1 is used, and there is a large difference between the mass of the rotating members of the hammer drill HR4. If the cooling fan of the hammer drill HR5 does not include a weight, there will be a large 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 the moment of inertia of the hammer drill HR4.

[0092] When a weight is added to the cooling fan of the hammer drill HR5 using the brushless motor BL type 1, the moment of inertia of the hammer drill HR5 and the moment of inertia of the hammer drill HR4 have similar values. Therefore, for the hammer drill HR5 using the brushless motor BL type 1, adding a weight to the cooling fan is useful for outputting the required impact energy. The same reasons as for the hammer drills HR4 and HR5 can also be applied to the hammers HM4 and HM5.

[0093] Furthermore, when the brushless motor BL type 2 is used with the hammer drill HR5, the mass of the rotating parts is 524 g, which is not significantly different from the mass of the rotating parts of the hammer drill HR4. Therefore, in this case, there is no need to include a weight in the cooling fan. This is the reason why, in the case where the brushless motor BL type 2 is used with the hammer drill HR5, the moment of inertia was calculated only when the cooling fan does not include a weight.

[0094] As another example, the mass of the rotating members of the hammer drill HR6 is 920 g. On the other hand, the mass of the rotating members of the hammer drill HR7 is 524 g when the brushless motor BL type 2 is used, which is a large difference from the mass of the rotating members of the hammer drill HR6.

[0095] The hammer drills HR6 and HR7 require greater impact energy than the hammer drills HR4 and HR5. In other words, greater output is required of the motor. For the brush motor (BR), the greater the required output, the larger the size and mass of the rotor. This is because the rotor of the brush motor (BR) is made up of a coil. In the brush motor (BR), the rotor coil is increased to increase output. Therefore, the mass of the rotating members of the brush motor (BR) used in the hammer drill HR6 is greater than the mass of the brush motor (BR) used in the hammer drill HR4.

[0096] On the other hand, for a brushless motor (BL), even if the required motor output increases, the rotor is made of a permanent magnet, so the size and mass of the rotor do not increase significantly. In other words, when the required motor output increases, the rate of increase in the size and mass of the rotating members of a brushless motor (BL) is smaller than the rate of increase in the size and mass of the rotating members of a brush motor (BR).

[0097] For these reasons, even if the brushless motor BL type 2 is used in the hammer drill HR7, there is a large difference in mass between the rotating members of the hammer drill HR7 and the rotating members of the hammer drill HR6. As a result, if the cooling fan of the hammer drill HR7 does not include a weight, there is a large difference in the moment of inertia between the hammer drill HR7 and 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.

[0098] On the other hand, if a weight is added to the cooling fan of the hammer drill HR7, the moment of inertia of the hammer drill HR7 and the moment of inertia of the hammer drill HR6 will be close to each other. Therefore, it is useful to add a weight to the cooling fan of the hammer drill HR7. The same reason can be applied to the hammers HM6, HM7, HM8, and HM9.

[0099] In this way, for impact tools equipped with a brushless motor (BL) that require an impact energy of 9.0 [J] or more, adding a weight (metal member) to the cooling fan to increase the moment of inertia is particularly useful for outputting the required impact energy.

[0100] In addition, by adding a weight to the cooling fan of a model using a brushless motor (BL) to optimize the moment of inertia for that model, the load current can be reduced while outputting the required impact energy when machining is performed, which results in a longer runtime for the battery-powered impact tool.

[0101] Below, using Figures 6 and 7, we will show that the load current can be reduced by adding a weight to the cooling fan of a model that uses a brushless motor and optimizing the moment of inertia of the rotating parts (rotor, motor shaft, cooling fan).

[0102] FIG. 6 shows the measured load current when the cooling fan of the hammer drill HR7 includes a weight and when the cooling fan of the hammer drill HR7 does not include a weight. In this measurement, the hammer drill HR7 was driven in hammer mode. In addition, FIG. 7 shows the measured load current when the cooling fan of the hammer HM7 includes a weight and when the cooling fan of the hammer HM7 does not include a weight. The measured values ​​in both FIG. 6 and FIG. 7 are the load current values ​​when a processing operation is performed while outputting the required impact energy. In addition, the pressing load on the workpiece during the measurement is the same in both FIG. 6 and FIG. 7. In the load current measurement when the cooling fan includes a weight, three values ​​of the moment of inertia were adopted by adjusting the mass of the weight, and the load current value at each value of the moment of inertia was measured. For this measurement, two types of tip tools (tip tools A and B) were attached to the hammer drill HR7 and the hammer HM7, and the load current value at each tip tool was measured.

[0103] As can be seen from these measurement results, when a weight is included in the cooling fan, there exists a value of the moment of inertia at which the load current value is smaller than when the cooling fan does not include a weight. In the measurement of the hammer drill HR7, for the three values ​​of the moment of inertia and all the tool tips (tool tips A and B), when a weight is included in the cooling fan, the load current value can be reduced more than when the weight is not included. In the measurement of the hammer HM7, for the three values ​​of the moment of inertia and all the tool tips (tool tips A and B), when a weight is included in the cooling fan, the load current value can be reduced more than when the weight is not included. Furthermore, in the measurement of the hammer drill HR7 and the measurement of the hammer HM7, when a weight is included in the cooling fan, there exists a value of the moment of inertia at which the load current value is smallest. Specifically, in the measurement of the hammer drill HR7, when a weight is included in the cooling fan and the moment of inertia is set to 2.5×10 -4 [kg m 2In addition, in the measurement of the hammer HM7, a weight was added to the cooling fan to make the moment of inertia 2.4×10 -4 [kg m 2 ], the load current value can be minimized. That is, when adjusting the moment of inertia by incorporating a weight in the cooling fan, there is an optimal value of the moment of inertia that can minimize the load current value. In an impact tool, by adjusting the mass of the weight included in the cooling fan to obtain the optimal moment of inertia that can minimize the load current value, the load power value when machining a workpiece can be effectively reduced.

[0104] Therefore, by adding a weight to the cooling fan of a model using a brushless motor to optimize the moment of inertia, it is possible to reduce the load current while maintaining the required impact energy output. Furthermore, as explained in Figure 5, adding a weight to the cooling fan is particularly effective in reducing the load current for models using brushless motors with a required impact energy value of 9.0 [J] or more.

[0105] In addition, as shown in Fig. 5, among the models using brushless motors, 1.6 × 10 -4 [kg m 2 For models that require a moment of inertia of 1.6×10 or more, adding a weight (metallic component) to the cooling fan is particularly useful for increasing the moment of inertia. -4 [kg m 2 For models of a size that require a moment of inertia of 1.6 x 10 , if the cooling fan does not include a weight (metallic component), there will be a large difference in the moment of inertia between the model and a model of the same size that uses a brush motor. -4 [kg m 2In models of a size that require a moment of inertia of 1000 V or more, incorporating a weight (metal component) into the cooling fan is particularly effective in increasing the moment of inertia while suppressing an increase in load current.

[0106] Also, as shown in FIG. 5, when the mass of the weight (metallic member) included in the cooling fan is 15% or more of the sum of the mass of the rotating member and the mass of the plastic member of the cooling fan, the moment of inertia of the rotating member and the cooling fan of an impact tool (hammer drill, hammer) driven by a brushless motor can be made equal to the moment of inertia of the rotor, motor shaft, and cooling fan of an impact tool (hammer drill, hammer) of the same size driven by a brush motor. For example, in the hammer HM5, the mass of the cooling fan is 114.6 [g]. The mass of the weight of the cooling fan is 74.5 [g]. Therefore, the mass of the plastic member of the cooling fan is 40.1 [g] (114.6-74.5). The sum of the mass (346 [g]) of the rotating member (BL type 1) and the mass (40.1 [g]) of the plastic member of the cooling fan is 386.1 [g] (346 + 40.1). The mass (74.5 g) of the weight (metallic component) included in the cooling fan is 15% or more of the sum of the mass of the rotating components and the mass of the plastic components of the cooling fan (386.1 g).

[0107] As shown in Figure 5, for models using brushless motors with a required impact energy value of 9.0 [J] or more, cooling fans with a diameter of 80 mm or more were used. When the diameter of the cooling fan is relatively large and a weight is included in the cooling fan, the moment of inertia can be increased efficiently. In other words, by making the diameter of the cooling fan 80 mm or more for models of this size, the moment of inertia can be increased efficiently while maintaining high cooling efficiency.

[0108] As described above, the hammer drill 101 in this embodiment uses a brushless motor as the motor 2 to drive the tool tip 18, and therefore can obtain the advantages of using a brushless motor. For example, compared to a configuration using a brush motor, the hammer drill 101 in this embodiment can eliminate the need for brush replacement, the motor 2 can be made smaller and lighter, and energy conversion efficiency can be improved. Also, in this embodiment, the cooling fan 7 includes the weight 73 (metal member), so the moment of inertia of the cooling fan 7 can be made larger than that of a cooling fan that does not include a metal member. Therefore, the moment of inertia of the rotating part including the rotating member (rotor 23, motor shaft 25) and the cooling fan 7 can be made larger. Furthermore, Weight 73 (metallic component) When viewed from the direction of the rotation axis of the cooling fan 7, the blades 72 are arranged at a position that overlaps at least the radial range of the cooling fan 7 in which they are arranged. This makes it possible to increase the moment of inertia of the cooling fan 7 compared to a configuration in which a metal member is arranged only on the periphery of the rotation axis of the cooling fan to increase the coupling strength with the motor shaft. This makes it possible to improve the impact energy that the hammer drill 101 can output. In this way, the hammer drill 101 of this embodiment can obtain the advantages of using a brushless motor, and can output the required impact energy while suppressing the load current when the hammer drill 101 is driven.

[0109] Furthermore, the cooling fan 7 can be easily manufactured because the resin member and the metal member are integrally molded. Moreover, the cooling fan 7 is provided with sufficient strength because it is integrally molded.

[0110] Furthermore, the portion of the cooling fan 7 that is connected to the motor shaft 25 is formed from a metal member (weight 73), and the cooling fan 7 is connected to the motor shaft 25 by pressing the motor shaft 25 into an insertion hole 71 provided in the cooling fan 7, thereby increasing the strength of the connection between the cooling fan 7 and the motor shaft 25.

[0111] Weight 73 (metal member) is positioned in a range at least outside half the radius of cooling fan 7 when viewed from the direction of rotation axis A2 of cooling fan 7, thereby making it possible to increase the moment of inertia of cooling fan 7 compared to a configuration in which a weight (metal member) of the same mass is positioned only inside half the radius of the cooling fan.

[0112] Furthermore, since the mass of weight 73 (metal member) is 15% or more of the sum of the mass of rotating member 26 and the mass of the resin member of cooling fan 7, the moment of inertia of rotating member 26 and cooling fan 7 can be made equivalent to the moment of inertia of a rotor, motor shaft, and cooling fan provided in an impact tool of an equivalent size driven by a brush motor.

[0113] The hammer drill 101 of this embodiment is provided with a cooling fan 7 having a diameter of 80 mm or more, so that the moment of inertia of the cooling fan 7 can be increased while maintaining high cooling efficiency.

[0114] Furthermore, the cooling fan 7 has the blades 72 arranged on one surface in the direction of the rotation axis A2, and the weight (metallic member) arranged on the other surface, so that the structure can be simplified.

[0115] In the above description, among the impact tools equipped with brushless motors, 1.6×10 -4 [kg m 2 For impact tools of a size requiring a moment of inertia of 1.6×10 or more, it has been shown that including a metal member in the cooling fan is particularly useful for increasing the moment of inertia. Therefore, in the hammer drill 101 of this embodiment, the moment of inertia of the rotating part including the rotating member 26 of the brushless motor (motor 2) and the cooling fan 7 is 1.6×10 -4 [kg m 2 ] As described above, by incorporating weight 73 in cooling fan 7, the moment of inertia can be effectively increased.

[0116] In the above description, it has been shown that for impact tools equipped with brushless motors that require an impact energy of 9.0 [J] or more, including a metallic member in the cooling fan to increase the moment of inertia is particularly useful for outputting the required impact energy. Since the hammer drill 101 in this embodiment is capable of outputting an impact energy of 9.0 [J] or more, the effect of increasing the moment of inertia by including the weight 73 (metallic member) in the cooling fan 7 can be further enhanced.

[0117] Furthermore, as described above, the cooling fan 7 includes the weight 73 (metallic member), which efficiently improves the moment of inertia, and therefore the load power required to output the required impact energy can be reduced. The hammer drill 101 of this embodiment includes a battery mounting section 15 configured to allow a rechargeable battery 19 to be attached / detached, and the motor 2 (brushless motor) is driven by power supplied from the battery 19 attached to the battery mounting section 15. Therefore, the cooling fan 7 includes the weight 73, which makes it possible to extend the runtime of the hammer drill 101 driven by power supplied from the battery 19.

[0118] In the hammer drill 101 of this embodiment, the direction in which the tool bit 18 is driven intersects with the rotation axis A2 of the motor 2 (brushless motor), so that the size of the hammer drill 101 can be made compact.

[0119] [Second embodiment] The second embodiment differs from the first embodiment in the configuration of the cooling fan.

[0120] The cooling fan 8 in the second embodiment will be described with reference to FIGS.

[0121] The cooling fan 8 has blades arranged on both sides (top and bottom) 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 from a resin member. The cooling fan 8 also has a weight 83 made of a metal member between the upper blade portion 82a and the lower blade portion 82b. In this embodiment, the cooling fan 8 In the above embodiment, the resin member and the metal member are integrally molded (insert molded), which simplifies the manufacturing process.

[0122] Also, similarly to the above-described first embodiment, the peripheral portion of the insertion hole 81 provided in the cooling fan 8 is formed of a metal member. In other words, a coupling portion 84 of the cooling fan 8 with the rotating member 26 (motor shaft 25) is formed of a metal member. Also, the motor shaft 25 is press-fitted into the insertion hole 81 provided in the radial center of the cooling fan 8, thereby coupling the cooling fan 8 to the rotating member 26. Therefore, since the motor shaft 25 is press-fitted into the insertion hole 81 of the metal member in the cooling fan 8, the strength of coupling between the cooling fan 8 and the motor shaft 25 can be increased.

[0123] As in the first embodiment, weight 83, which is a metal member, is disposed at a position overlapping at least the radial range of cooling fan 8 in which upper blade portion 82a and lower blade portion 82b are disposed, when viewed from the direction of rotation axis A2 (vertical direction). By employing such a configuration, the moment of inertia of cooling fan 8 can be increased.

[0124] Furthermore, the weight 83, which is a metal member, is at least a part of the cooling fan when viewed from the direction of the rotation axis A2. 8 Therefore, the cooling fan 8 The moment of inertia can be increased.

[0125] In this embodiment, the cooling fan 8 has a diameter of 80 mm or more. Therefore, the moment of inertia of the cooling fan 8 can be increased.

[0126] Furthermore, in this embodiment, the mass of the weight 83 (metal member) included in the cooling fan 8 is 15% or more of the sum of the mass of the rotating member 26 including the rotor 23 and the motor shaft 25 and the mass of the resin member included in the cooling fan 8.

[0127] In this embodiment, the moment of inertia of the rotating part 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 m 2 In this embodiment, the cooling fan 8 having such a configuration is applied to a relatively large hammer drill 101 that can output impact energy of 9.0 [J] or more in the hammer mode.

[0128] As described above, the hammer drill 101 in this embodiment includes the cooling fan 8. The cooling fan 8 has blade portions (upper blade portion 82a and lower blade portion 82b) arranged on both sides in the direction of the rotation axis A2, so that the amount of air blown by the cooling fan can be increased and the cooling efficiency can be improved. Also, as in the first embodiment, the cooling fan 8 includes the weight 83, so that the same effect as in the first embodiment can be obtained. That is, the moment of inertia of the cooling fan 8 can be increased, and the impact energy can be improved while suppressing the load power.

[0129] The correspondence between each component of the above embodiment and each component of the present invention is shown below. However, each component of the above embodiment is merely an example and does not limit each component of the present invention. The hammer drill 101, the hammer drill shown in FIG. 5, and the hammer are examples of the "impact tool" of the present invention. The tip tool 18 and the tip tools A and B shown in FIG. 6 and FIG. 7 are examples of the "tip tool" of the present invention. The cooling fan 7 and the cooling fan 8 are examples of the "cooling fan" of the present invention. The rotating member 26 including the rotor 23 and the motor shaft 25 is an example of the "rotating member" of the present invention. The weights 73 and 83 are examples of the "metal member" of the present invention. The configuration consisting of the rotating member 26 (the rotor 23 and the motor shaft 25) and the cooling fan 7 is an example of the "rotating part" of the present invention. The battery mounting part 15 is an example of the "battery mounting part" of the present invention. The battery 19 is an example of the "battery" of the present invention.

[0130] The above embodiment is merely an example, and the impact tool according to the present invention is not limited to a hammer drill and a hammer, which are impact tools that drive a tool tip linearly along a drive shaft. Other impact tools can be used as long as the tool tip is driven by the rotational force of a rotor and a motor shaft that are rotated by driving a brushless motor, and the tool tip is driven by the rotational force of the rotor and the motor shaft.

[0131] In the above embodiment, the cooling fans 7 and 8 are directly connected to the motor shaft 25, but other configurations may be adopted. The cooling fans may be connected to the motor shaft 25 via gears or other connecting parts. That is, a configuration may be adopted in which the rotational force of the motor shaft 25 is transmitted to the cooling fans via gears or other connecting parts, causing the cooling fans to rotate. Even if such a configuration is adopted, if a weight (metal member) is included in the cooling fans, the moment of inertia involved in the impact energy output by the impact tool can be increased, and the same effect as in the above embodiment can be obtained.

[0132] In addition, in the above embodiment, various metal members can be used as the metal members for the weight, such as iron, copper, silver, lead, tin, stainless steel, brass, aluminum, tungsten, or alloys containing these metals.

[0133] In the above embodiment, the weight (metal member) is configured to be positioned from inside half the radius of the cooling fan to outside half the radius of the cooling fan when viewed from the direction of the cooling fan's rotational axis, but a configuration in which the weight is positioned only outside half the radius of the cooling fan may also be adopted.

[0134] Alternatively, a configuration may be adopted in which a portion of the blade of the cooling fan is made of a metal member, a weight is disposed on the pressure surface or the negative pressure surface of the blade of the cooling fan, or the weight is disposed in multiple regions of the cooling fan.

[0135] Furthermore, in consideration of the spirit of the present invention and the above-mentioned embodiment and its modified examples, the following aspects are constructed. The following aspects can be adopted in combination with the configurations shown in the embodiment.

[0136] [Aspect 1] The mass of the metal member (weight) included in the cooling fan is set so that the load current value is minimized when the impact tool is driven so that the pressing load on the workpiece is a constant value.

[0137] [Aspect 2] The moment of inertia of the rotating part, including the rotating member of the brushless motor and the cooling fan, is set so that the load current value is smallest when the impact tool is driven so that the pressing load on the workpiece is a constant value. [Explanation of symbols]

[0138] 2...motor, 3...drive mechanism, 4...mode switching 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 section, 18...tool, 19...battery, 21...stator, 23...rotor, 25...motor shaft, 26...rotating member, 28...drive gear, 30...motion conversion mechanism, 34...tool holder, 36...striking element, 38...rotation transmission mechanism, 39...clutch, 40...clutch switching mechanism, 41...operation section, 71. ..through hole, 72...wing portion, 73...weight, 74...connecting portion, 81...through hole, 82a...upper wing portion, 82b...lower wing portion, 83...weight, 84...connecting portion, 101...hammer drill, 111...drive mechanism accommodating portion, 117...motor accommodating portion, 131...gripping portion, 133...upper portion, 137...lower portion, 141...locking projection, 145...main switch, 171...elastic member, 175...elastic member, 731...through hole, A1...drive shaft, A2...rotating shaft, R...rotating shaft, r1 to r4...radius, HR1 to HR7...hammer drill, HM2 to HM10...hammer

Claims

1. An impact tool that drives a tool tip, a brushless motor having a rotating member including a rotor and a motor shaft, and driving the tool bit by a rotational force of the rotating member; a cooling fan coupled to the motor shaft within a housing of the impact tool, the cooling fan having a blade portion and rotating by a rotational force of the rotating member to cool at least the brushless motor; Equipped with The cooling fan includes a resin member and a metal member, the metallic member is disposed at a position overlapping at least a radial range of the cooling fan in which the blade portion is disposed, when viewed from a direction of a rotation axis of the cooling fan, The impact energy that the impact tool can output is 9.0 [J] or more, The moment of inertia of the rotating part including the rotating member and the cooling fan of the brushless motor is 1.6×10 －４ [kg m ２ ] and above, 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. An impact tool characterized by

2. The impact tool according to claim 1, a motion conversion mechanism that converts the rotational motion of the rotating part including the cooling fan into linear motion of a piston and transmits the linear motion of the piston to the tool bit via an air spring; An impact tool characterized by

3. The impact tool according to claim 2, The motion conversion mechanism includes: The rotational motion of the rotating part is converted into the linear motion of the tool bit via a crankshaft. An impact tool characterized by

4. An impact tool according to any one of claims 1 to 3, The cooling fan is formed by integrally molding the resin member and the metal member. An impact tool characterized by

5. An impact tool according to any one of claims 1 to 4, The metal member is disposed in a range at least outside half the radius of the cooling fan when viewed from the direction of the rotation axis of the cooling fan. An impact tool characterized by

6. An impact tool according to any one of claims 1 to 5, the cooling fan is coupled to the motor shaft; a portion of the cooling fan that is coupled to the motor shaft is formed from the metal member; The motor shaft is press-fitted into an insertion hole provided in the cooling fan, whereby the cooling fan is coupled to the motor shaft. An impact tool characterized by

7. An impact tool according to any one of claims 1 to 6, The diameter of the cooling fan is 80 mm or more. An impact tool characterized by

8. An impact tool according to any one of claims 1 to 7, The cooling fan has the blade portion disposed on one surface in the direction of the rotation axis of the cooling fan, and the metal member disposed on the other surface in the direction of the rotation axis of the cooling fan. An impact tool characterized by

9. An impact tool according to any one of claims 1 to 8, The cooling fan has the blades arranged on both sides in the direction of the rotation axis of the cooling fan, and the metal member is arranged between the blades arranged on both sides. An impact tool characterized by

10. An impact tool according to any one of claims 1 to 9, The impact tool is configured to perform a processing operation on a workpiece by linearly driving the tip tool, The direction in which the tool bit is driven and the rotation axis of the brushless motor intersect. An impact tool characterized by

11. An impact tool according to any one of claims 1 to 10, A battery mounting section is provided that is configured to allow a rechargeable battery to be attached and detached, The brushless motor is driven by power supplied from the battery attached to the battery attachment section. An impact tool characterized by

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