power tools

Abstract

We provide technology to improve the user experience of power tools. [Solution] The power tool comprises a motor, a spindle, and a planetary gear mechanism. The spindle rotates due to the rotational force transmitted from the motor. The planetary gear mechanism transmits the rotational force from the motor to the spindle. The rotation axis of the motor and the rotation axis of the spindle are arranged on the same straight line. The planetary gear mechanism has a sun gear, a plurality of planetary gears, a carrier, and an internal gear. The sun gear receives rotational force from the motor. The plurality of planetary gears are arranged radially outward from the rotation axis of the sun gear. The carrier is fixed so as not to rotate relative to the sun gear and supports the plurality of planetary gears so as to be able to rotate. The internal gear is rotatably arranged radially outward from the plurality of planetary gears and transmits rotational force to the spindle.

Description

Technical Field

[0001] The present disclosure relates to power tools.

Background Art

[0002] Among power tools equipped with a planetary gear mechanism as a speed reducer, in a power tool in which the rotation axis of the motor and the rotation axis of the spindle are arranged on the same straight line, a configuration using the planetary gear mechanism in a planetary operation mode is adopted. When the planetary gear mechanism is used in the planetary operation mode, the rotational force from the motor is input to the sun gear, the internal gear is fixed, the planetary gear rotates and revolves, and the driving force is output from the carrier (planetary carrier) that supports the planetary gear.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a power tool that operates a planetary gear mechanism in a planetary type, the rotation direction of the motor and the rotation direction of the carrier are the same. That is, the spindle to which the rotational force is transmitted from the carrier also rotates in the same direction as the motor. Among power tools, particularly in an impact tool equipped with a hammer that imparts an impact in the rotation direction, the rotation directions of members such as the motor, carrier, spindle, hammer, and anvil are the same. In the case of a power tool having such a configuration, at the start-up or stop, the moment of inertia of these members rotating in the same rotation direction increases, and a phenomenon occurs in which the power tool body vibrates in the direction opposite to the rotation direction of the motor. As a result, at the start-up or stop of the power tool, the user's hand is shaken, and the work load is large.

[0005] One non-limiting purpose of this disclosure is to provide improvements that contribute to reducing the burden on the user when working with power tools. [Means for solving the problem]

[0006] One non-limiting aspect of this disclosure provides a power tool comprising a motor, a spindle, and a planetary gear mechanism. The spindle rotates by a rotational force transmitted from the motor. The planetary gear mechanism transmits the rotational force from the motor to the spindle. The rotation axis of the motor and the rotation axis of the spindle are collinear. The planetary gear mechanism comprises a sun gear, a plurality of planetary gears, a carrier, and an internal gear. The sun gear receives the rotational force from the motor. The plurality of planetary gears are arranged radially outward from the rotation axis of the sun gear. The carrier is fixed to the sun gear so as not to rotate and supports the plurality of planetary gears so as to rotate. The internal gear is rotatably positioned radially outward from the plurality of planetary gears and transmits the rotational force to the spindle.

[0007] According to this embodiment, the planetary gear mechanism is configured to operate in a star configuration with the carrier fixed so as not to rotate. When the planetary gear mechanism operates in a star configuration, the direction of rotation of the motor and the direction of rotation of the internal gear and spindle are opposite. As a result, the moment of inertia due to the rotation of the motor and the moment of inertia due to the rotation of the internal gear and spindle cancel each other out, and the phenomenon of the power tool body being shaken by the moment of inertia during initial operation and stopping of the power tool can be suppressed. Therefore, the load on the user when working with the power tool can be reduced, and the user experience of the power tool can be improved.

[0008] Furthermore, the statement that the motor's rotation axis and the spindle's rotation axis are aligned on the same line does not mean that they are perfectly aligned on the same line. It also includes cases where the motor's rotation axis and the spindle's rotation axis are approximately aligned on the same line. Finally, it includes cases where the motor's rotation axis and the spindle's rotation axis are slightly off the same line due to manufacturing tolerances, gaps, looseness, or play in the rotation axis.

[0009] Another non-limiting aspect of this disclosure provides a power tool comprising a motor and a spindle, the spindle rotating by a rotational force transmitted from the motor. The axis of rotation of the motor and the axis of rotation of the spindle are parallel or collinear. The direction of rotation of the motor and the direction of rotation of the spindle are opposite.

[0010] According to this embodiment, since the rotation direction of the motor and the rotation direction of the spindle are opposite, the moment of inertia due to the rotation of the motor and the moment of inertia due to the rotation of the spindle cancel each other out, and the phenomenon of the power tool body being shaken by the moment of inertia when the power tool is started and stopped can be suppressed. Therefore, the load on the user when working with the power tool can be reduced and the user experience of the power tool can be improved.

[0011] Furthermore, the statement that the motor's rotation axis and the spindle's rotation axis are parallel is not limited to cases where they are perfectly parallel. It also includes cases where they are approximately parallel. Finally, it includes cases where, due to manufacturing tolerances, clearances, looseness, or play in the rotation axes, the motor's rotation axis and the spindle's rotation axis are slightly deviated from their parallel positions. [Brief explanation of the drawing]

[0012] [Figure 1] This is a perspective view of an impact tool according to the first embodiment. [Figure 2] This is a longitudinal cross-section of an impact tool. [Figure 3] This is a vertical cross-sectional view showing the top of an impact tool. [Figure 4] This is an exploded view of the power transmission mechanism of an impact tool. [Figure 5] This is an explanatory diagram showing the relationship between the planetary gear mechanism and the spindle. [Figure 6] This is an explanatory diagram illustrating the configuration of a planetary gear mechanism and spindle. [Figure 7] This is an exploded perspective view of the planetary gear mechanism and spindle. [Figure 8] This is an explanatory diagram showing the relationship between the spindle and the inner hammer. [Figure 9] This is a schematic diagram of the impact tool according to the second embodiment. [Modes for carrying out the invention]

[0013] Hereinafter, representative and non-limiting examples of the present invention will be described in detail with reference to the drawings. This detailed description is intended solely to show those skilled in the art details for carrying out preferred examples of the present invention and is not intended to limit the scope of the present invention. Furthermore, additional features and inventions disclosed below may be used separately from or in conjunction with other features and inventions to provide further improved apparatus, methods for manufacturing and using the same.

[0014] Furthermore, the combinations of features and processes disclosed in the following detailed description are not essential for carrying out the present invention in the broadest sense, and are described solely to illustrate representative examples of the present invention. Moreover, the various features of the representative examples described above and below, as well as the various features described in the independent and dependent claims, do not necessarily have to be combined in the same way as the examples described herein or in the order listed, in order to provide additional and useful embodiments of the present invention.

[0015] In one or more non-limiting embodiments of the present disclosure, the power tool may include a housing that houses at least a part of the planetary gear mechanism, and a carrier fixing member that fixes the carrier to the housing in a non-rotatable manner.

[0016] According to this embodiment, the carrier can be fixed to the housing in a non-rotatable manner via the carrier fixing member. Thus, the carrier can be firmly fixed so that the planetary gear to which a strong rotational force from the motor (sun gear) is applied does not revolve. As a result, the rotational force of the sun gear can be transmitted to the internal gear without being weakened by the planetary gear and the carrier.

[0017] In addition to or instead of the above embodiment, the internal gear and the spindle may be configured as separate bodies.

[0018] According to this embodiment, when manufacturing the internal gear and the spindle, they can be manufactured more simply than when formed integrally. Also, it becomes easier to use different materials for the respective members than when the internal gear and the spindle are formed integrally.

[0019] In addition to or instead of the above embodiment, the internal gear and the spindle may be connected so as to be relatively movable in the axial direction of the rotation axes of the internal gear and the spindle.

[0020] According to this embodiment, it is possible to suppress the vibration in the axial direction of the rotation axis from the spindle from being transmitted to the internal gear when the power tool is driven. As a result, the durability of the planetary gear mechanism can be improved.

[0021] In addition to or instead of the above embodiment, the internal gear and the spindle may be connected by splines in the axial direction of the rotation axes of the internal gear and the spindle.

[0022] According to this embodiment, when driving a power tool, it is possible to suppress the transmission of axial vibrations of the rotating shaft from the spindle to the internal gear, while simultaneously enabling the transmission of rotational power from the internal gear to the spindle, and providing a structure with excellent self-alignment capabilities.

[0023] In addition to or in lieu of the above embodiments, the carrier fixing member may have a gear-shaped first locking portion with a plurality of teeth formed in the circumferential direction around the rotation axis of the sun gear. The housing may have a second locking portion that engages with the first locking portion.

[0024] According to this embodiment, since the carrier fixing member is fixed to the housing by a circumferential gear shape, the housing can easily receive the rotational force of the carrier. As a result, the carrier can be indirectly and firmly fixed to the housing.

[0025] In addition to or instead of the above embodiments, the carrier may be made of metal. The carrier fixing member may be made of resin.

[0026] According to this embodiment, the strength of the carrier can be increased by using a metal component for the carrier that receives force from the planetary gear, while the weight can be reduced by using a resin component for the carrier fixing member.

[0027] In addition to, or in place of, the above embodiments, a hammer may be provided, which is positioned around the spindle and is capable of rotating in the same direction as the spindle by the rotational force of the spindle. An anvil may also be provided, which at least a portion of which is positioned in front of the spindle and is struck in the rotational direction by the hammer.

[0028] According to this embodiment, by canceling out the moment of inertia due to the rotation of the motor and the moment of inertia due to the rotation of the hammer, it is possible to suppress the phenomenon of the power tool body being shaken in the rotational direction during initial movement and stopping, thereby improving the user experience of the power tool.

[0029] In other, non-limiting embodiments of this disclosure, a power tool comprising a motor and a spindle may be employed. The spindle may be rotated by a rotational force transmitted from the motor. The axis of rotation of the motor and the axis of rotation of the spindle may be parallel or collinear. The direction of rotation of the motor and the direction of rotation of the spindle may be opposite.

[0030] According to this embodiment, since the rotation direction of the motor and the rotation direction of the spindle are opposite, the moment of inertia due to the rotation of the motor and the moment of inertia due to the rotation of the spindle cancel each other out. This suppresses the phenomenon of the power tool body being shaken by the moment of inertia when the power tool is started and stopped, thereby improving the user experience of the power tool.

[0031] In addition to, or in place of, the above embodiments, a planetary gear mechanism may be provided to transmit the rotational force of the motor to the spindle. The planetary gear mechanism may include a sun gear, a planetary gear, a carrier that supports the planetary gear so as to be able to rotate, and an internal gear. The rotational force of the motor may be input to the sun gear. The carrier may be fixed so as not to rotate. The internal gear may be rotatable. The rotational force of the internal gear may be output to the spindle.

[0032] According to this embodiment, the planetary gear mechanism is configured to operate in a star configuration with the carrier fixed so as not to rotate. When the planetary gear mechanism operates in a star configuration, the direction of rotation of the motor and the direction of rotation of the internal gear and spindle are opposite. As a result, the moment of inertia due to the rotation of the motor and the moment of inertia due to the rotation of the internal gear and spindle cancel each other out, which can suppress the phenomenon of the power tool body being shaken by the moment of inertia when the power tool is started and stopped, and can improve the user experience of the power tool.

[0033] A. First Embodiment: An impact tool 1, as an example of a power tool according to a representative and non-limiting embodiment of this disclosure, will be described in detail with reference to the drawings. First, the configuration of the impact tool 1 will be described. Then, the operation of the impact tool 1 will be described.

[0034] [Impact tool configuration] Referring to Figures 1 to 3, the configuration of the impact tool 1 will be described. In this embodiment, the impact tool 1 is an impact driver.

[0035] The impact tool 1 is an electric tool that enables screw tightening by rotating the anvil 81 while applying rotational impact to the tip tool (e.g., a screwdriver bit) inserted into the anvil 81. Specifically, when the user pulls the trigger lever 26, which is an operating part located on the grip portion 22 of the impact tool 1, power is supplied from the battery pack 10 to the motor 40 via the controller 29, causing the rotor 44 of the motor 40 to rotate. The rotational force output from the motor 40 is transmitted to the spindle 60 via a planetary gear mechanism 50 that functions as a reduction gear. The rotational force transmitted to the spindle 60 is transmitted to the anvil 81 via an inner hammer 78, which is part of the impact mechanism 70. As the anvil 81 rotates, the tip tool inserted into the anvil 81 rotates, enabling screw tightening. When rotational resistance occurs between the screw and the workpiece during screw tightening, and a load exceeding a predetermined level is applied to the anvil 81, the inner hammer 78 and outer hammer 73, which are part of the impact mechanism 70, apply an impact force to the anvil 81. The anvil 81 rotates the screw while applying rotational force and an impact force in the rotational direction to the screw. In this way, the impact tool 1 enables screw tightening.

[0036] In this embodiment, the direction parallel to the rotation axis AX of the motor 40 is defined as the front-rear direction. Of the front-rear direction, the side on which the spindle 60 is positioned relative to the motor 40 is defined as the front side, and the opposite side of the front side is defined as the rear side. Of the directions perpendicular to the axial direction of the rotation axis AX, the direction in which the grip portion 22 extends is defined as the up-down direction. Of the up-down direction, the side on which the grip portion 22 is positioned relative to the motor 40 is defined as the down side, and the opposite side of the down side is defined as the up side. The direction perpendicular to the up-down direction and the front-rear direction is defined as the left-right direction of the impact tool 1.

[0037] The impact tool 1 comprises a main housing 2, a rear cover 3, and a hammer housing 4. The main housing 2 is made of synthetic resin. The main housing 2 consists of a pair of split housings, which are a right housing and a left housing. The right housing and the left housing are fixed together by a number of screws 2S.

[0038] The main housing 2 has a motor housing section 21, a grip section 22, and a battery holding section 23.

[0039] The motor housing 21 has a cylindrical shape and houses the motor 40 inside. The motor housing 21 also houses a portion of the hammer housing 4. The internal structure of the motor housing 21 will be described later.

[0040] The grip section 22 is held by the user when using the impact tool 1. The grip section 22 extends downward from the motor housing section 21. A trigger lever 26 and a forward / reverse rotation switch lever 27 are located at the top of the grip section 22. The trigger lever 26 is an operating part operated by the user to start the motor 40. When the trigger lever 26 is pulled by the user, the motor 40 is driven. When the user releases the pull of the trigger lever 26, the motor 40 stops. The forward / reverse rotation switch lever 27 is an operating part operated by the user to switch the rotation direction of the motor 40 from one direction to the other. When the rotation direction of the motor 40 is switched, the rotation direction of the spindle 60 and the anvil 81 is also switched.

[0041] The battery holder 23 is connected to the lower end of the grip portion 22. The battery holder 23 holds the battery pack 10 via the battery mounting portion 28. The external dimensions of the battery holder 23 are larger than those of the grip portion 22 in the front-to-back and left-to-right directions.

[0042] The rear cover 3 is positioned to cover the opening at the rear end of the motor housing 21. The rear cover 3 is made of synthetic resin. The rear cover 3 houses at least a portion of the fan 31. The rear cover 3 also houses the rear rotor bearing 32. The rear rotor bearing 32 rotatably supports the rear end of the rotor shaft 45 of the motor 40.

[0043] The motor housing 21 has an air intake 24. The rear cover 3 has an exhaust port 25. As the fan 31 rotates, air from outside the main housing 2 flows into the internal space of the main housing 2 through the air intake 24. The air in the internal space of the main housing 2 flows out to the external space of the main housing 2 through the exhaust port 25.

[0044] The fan 31 is positioned between the stator 41 (motor 40) and the rear rotor bearing 32. The fan 31 is fixed to the rear of the rotor shaft 45 of the motor 40. When the motor 40 is started, the fan 31 rotates together with the rotor shaft 45, generating an airflow to cool the motor 40. As the fan 31 rotates, air from the external space of the main housing 2 flows into the internal space of the main housing 2 through the intake port 24. The air that flows into the internal space of the main housing 2 cools the motor 40 by circulating through the internal space of the main housing 2. As the fan 31 rotates, the air that has circulated through the internal space of the main housing 2 flows out into the external space of the main housing 2 through the exhaust port 25.

[0045] Motor 40 will be described with reference to Figure 3. Motor 40 is the power source for impact tool 1. Motor 40 is an inner rotor type brushless motor. Motor 40 has a stator 41 and a rotor 44.

[0046] The stator 41 is supported by the motor housing 21. The stator 41 has a stator core 42 and a coil 43.

[0047] At least a portion of the rotor 44 is positioned inside the stator 41. The rotor 44 rotates relative to the stator 41. The rotor 44 rotates around a rotation axis AX that extends in the longitudinal direction. The rotor 44 has a rotor shaft 45, a rotor core 46, a rotor magnet 47, and a sensor magnet 48.

[0048] The rotor shaft 45 and the rotor core 46 are each made of steel. In this embodiment, the rotor shaft 45 and the rotor core 46 are integrated. The front portion of the rotor shaft 45 protrudes forward from the front end surface of the rotor core 46. The rear portion of the rotor shaft 45 protrudes rearward from the rear end surface of the rotor core 46.

[0049] The rotor magnet 47 is fixed to the rotor core 46. In this embodiment, the rotor magnet 47 is arranged around the rotor core 46. The sensor magnet 48 is fixed to the rotor core 46. In this embodiment, the sensor magnet 48 is arranged on the front end face of the rotor core 46.

[0050] A sensor substrate 49 is positioned at the front end of the stator 41. The sensor substrate 49 has an annular circuit board and a rotation detection element supported by the circuit board. At least a portion of the sensor substrate 49 faces the front end surface of the sensor magnet 48. The rotation detection element detects the position of the rotor 44 in the rotational direction by detecting the position of the sensor magnet 48.

[0051] The rear end of the rotor shaft 45 is rotatably supported by the rear rotor bearing 32. The rear rotor bearing 32 is held in place by the rear cover 3.

[0052] A pinion gear 58 is fixed to the front end of the rotor shaft 45. The rotor shaft 45 is connected to a planetary gear mechanism 50, which is a reduction gear, via the pinion gear 58. The pinion gear 58 functions as a sun gear in the planetary gear mechanism 50. That is, the power (rotational force) of the motor 40 is input to the planetary gear mechanism 50 via the pinion gear 58. The power of the motor 40 is output from the cutting tool via a power transmission mechanism that includes the planetary gear mechanism 50, a spindle 60, a striking mechanism 70, and an anvil 81.

[0053] Referring to Figures 3 to 8, the power transmission mechanism that transmits power from the motor 40 will be described.

[0054] The planetary gear mechanism 50 will now be described. In this embodiment, the planetary gear mechanism 50 is configured to operate in a star configuration. Generally, when a planetary gear mechanism operates in a star configuration, the sun gear is rotatable. The planetary gears are rotatable. The carriers supporting the planetary gears are fixed in a non-rotatable manner. Because the carriers supporting the planetary gears are fixed in a non-rotatable manner, the planetary gears are rotatable, but they cannot revolve around the sun gear. The internal gears are rotatable. The configuration of the planetary gear mechanism 50 will now be described in detail.

[0055] As shown in Figure 4, the planetary gear mechanism 50 includes a carrier fixing member 51, an O-ring 53, a carrier 55, a gear shaft pin 56, a planetary gear 57, a pinion gear 58, and an internal gear 59.

[0056] An opening 55A is formed in the center of the carrier 55. A circular groove-shaped bearing fixing portion 55B is formed in the center of the rear side of the carrier 55 (Figure 7). The opening 55A and the bearing fixing portion 55B are in communication. The pinion gear 58 passes through the opening 55A. The front rotor bearing 33 is held in the bearing fixing portion 55B from the rear side of the carrier 55. The front rotor bearing 33 functions as a bearing for the pinion gear 58. As described above, the pinion gear 58 is connected to the rotor shaft 45 of the motor 40. Power from the motor 40 is input to the planetary gear mechanism 50 via the pinion gear 58.

[0057] The pinion gear 58 functions as the sun gear in the planetary gear mechanism 50. Three planetary gears 57 are arranged around the radially outer circumference of the pinion gear 58, which has a rotation axis. Each planetary gear 57 is rotatably supported on the carrier 55 by a gear shaft pin 56. The pinion gear 58 and the three planetary gears 57 mesh with each other. As the pinion gear 58 rotates, each planetary gear 57 rotates around the gear shaft pin 56 as its axis of rotation.

[0058] The carrier fixing member 51 has a through-hole, which is a holding portion 51A. The carrier 55 is fitted into and held in the holding portion 51A. In this embodiment, the carrier 55 is a metal member, and the carrier fixing member 51 is a resin member. By making the carrier 55, which receives force from the planetary gear 57, a metal member, the strength of the carrier 55 can be increased. Also, by making the carrier fixing member 51 a resin member, weight can be reduced. In this embodiment, the carrier 55 and the carrier fixing member 51 are integrally molded by insert molding.

[0059] A gear-shaped first locking portion 51B is formed on the periphery of the carrier fixing member 51. A second locking portion 4B is formed on the hammer housing 4, which fits into the first locking portion 51B of the carrier fixing member 51. The second locking portion 4B has teeth and grooves formed in the front-rear direction. The first locking portion 51B of the carrier fixing member 51 and the second locking portion 4B of the hammer housing 4 fit together, so that the carrier fixing member 51 is firmly fixed so that it does not rotate around the rotation axis AX.

[0060] The carrier fixing member 51 is fixed to the hammer housing 4, and the carrier 55 is fixed to the carrier fixing member 51, so the carrier 55 is fixed in a way that it cannot rotate in the rotational direction around the rotation axis AX. In other words, the carrier 55 is fixed in a way that it cannot rotate relative to the sun gear, which is the pinion gear 58. Therefore, when the motor 40 is driven and the pinion gear 58 rotates, the three planetary gears 57 supported by the carrier 55 rotate on their own axis, but they do not revolve around the sun gear (pinion gear 58).

[0061] An O-ring 53 is placed between the carrier fixing member 51 and the hammer housing 4. The inside of the hammer housing 4 is filled with grease. By placing the O-ring 53 between the carrier fixing member 51 and the hammer housing 4, it is possible to prevent grease from leaking out of the hammer housing 4 from the connection between the carrier fixing member 51 and the hammer housing 4.

[0062] The internal gear 59 is located outside the three planetary gears 57. The internal gear 59 is cylindrical. A flat surface is formed on the front of the cylindrical internal gear 59, and a circular opening 59B is formed on this surface. The internal gear 59 houses the three planetary gears 57 inside its cylindrical body. The internal gear 59 has gears formed on the inner wall 59A of the cylindrical body, which mesh with each of the three planetary gears 57.

[0063] When the motor 40 is driven and the rotor shaft 45 rotates, the pinion gear 58, acting as a sun gear, rotates in the same direction as the rotor shaft 45. As the pinion gear 58 rotates, the three planetary gears 57 rotate on the gear shaft pin 56 as their axis of rotation. At this time, the three planetary gears 57 do not revolve. Then, the rotation of the three planetary gears 57 causes the internal gear 59 to rotate. When viewed from the direction of the rotation axis AX, the direction of rotation of the pinion gear 58 and the direction of rotation of the internal gear 59 are opposite. The internal gear 59 is connected to rotate together with the spindle 60, which will be described later. That is, the direction of rotation of the rotor 44 of the motor 40 is opposite to the direction of rotation of the internal gear 59 and the spindle 60.

[0064] By adopting this configuration, when the impact tool 1 is driven, the moment of inertia caused by the rotor 44 due to the rotation of the motor 40 cancels out the moment of inertia caused by the rotation of the internal gear 59 and spindle 60, thereby suppressing the phenomenon in which the impact tool 1 body is shaken by the moment of inertia during initial movement and stopping of the impact tool 1.

[0065] Furthermore, the impact tool 1 in this embodiment includes an outer hammer 73 and an inner hammer 78, which will be described later. When the motor 40 rotates, the rotation directions of the internal gear 59, spindle 60, outer hammer 73, and inner hammer 78 are the same. Therefore, when the impact tool 1 is driven, the moment of inertia caused by the rotor 44 due to the rotation of the motor 40 cancels out the moment of inertia caused by the internal gear 59, spindle 60, outer hammer 73, and inner hammer 78, thereby suppressing the phenomenon of the impact tool 1 being shaken by the moment of inertia at the start and stop of the impact tool 1. The impact tool 1 is designed so that the magnitude of the moment of inertia caused by the rotor 44 due to the rotation of the motor 40 is approximately the same as the magnitude of the moment of inertia caused by the internal gear 59, spindle 60, outer hammer 73, and inner hammer 78.

[0066] Furthermore, the impact tool 1 in this embodiment does not include components such as bearings for aligning the shaft of the internal gear 59. The reason for this will be explained below.

[0067] The rotor shaft 45 is rotatably supported by the rear rotor bearing 32. The pinion gear 58, which is fixed to the rotor shaft 45, is rotatably supported by the front rotor bearing 33. Therefore, the axis of rotation of the pinion gear 58 connected to the rotor shaft 45 coincides with the axis of rotation of the motor 40 AX. In other words, the pinion gear 58 is axially aligned, and its axis of rotation is positioned in the correct location.

[0068] The planetary gear 57 is also in a state where its axis is aligned. That is, the rotation axis of the planetary gear 57 is positioned in the appropriate location by the carrier fixing member 51, the carrier 55, and the gear shaft pin 56.

[0069] When two of the three types of gears (sun gear, planetary gear, and internal gear) in the planetary gear mechanism 50 are aligned, the remaining gear will be aligned automatically due to its self-aligning ability, even without the need for bearings or other components. In this embodiment, the pinion gear 58 (sun gear) and the planetary gear 57 are aligned. Therefore, the rotation axis of the internal gear 59 will align with the rotation axis AX of the motor 40 without the need for bearings or other components to align the internal gear 59. In other words, the impact tool 1 of this embodiment does not require a bearing for aligning the internal gear 59. As a result, the impact tool 1 of this embodiment can be simplified in structure, made lighter, and reduced in cost.

[0070] The internal gear 59 has a connecting portion 59C on the periphery of the opening 59B for connecting to the spindle 60. On the other hand, the spindle 60 has a connecting portion 60C for connecting to the internal gear 59. The connecting portion 59C of the internal gear 59 and the connecting portion 60C of the spindle 60 are connected by a spline in the axial direction of the rotating shaft AX. That is, the internal gear 59 and the spindle 60 are connected so as to be relatively movable in the axial direction of the rotating shaft AX. Therefore, when the impact tool 1 is driven, the transmission of axial vibrations of the rotating shaft AX transmitted from the spindle 60 to the internal gear 59 can be suppressed. As a result, the durability of the planetary gear mechanism 50 can be improved. Furthermore, by connecting the internal gear 59 and the spindle 60 by a spline, it is possible to realize a structure with excellent ability to transmit rotational force from the internal gear 59 to the spindle 60 and excellent self-alignment.

[0071] The configuration of the planetary gear mechanism 50 has been described above. Next, the other components of the power transmission mechanism that transmits power from the motor 40 will be described.

[0072] A spindle 60 is positioned in front of the planetary gear mechanism 50. The spindle 60 rotates around the rotation axis AX by the motor 40. The spindle 60 rotates due to the rotational force of the rotor 44 transmitted via the planetary gear mechanism 50. More specifically, the spindle 60 rotates due to the rotational force transmitted between the connection part 59C of the internal gear 59 of the planetary gear mechanism 50 and the connection part 60C of the spindle 60. The spindle 60 outputs the rotational force of the motor 40 transmitted from the planetary gear mechanism 50 to the striking mechanism 70, which will be described later.

[0073] The spindle 60 has a spindle shaft portion 60A, a flange portion 60B, a connecting portion 60C, a tip opening 60D, and a spindle groove 61. The spindle shaft portion 60A is a rod-shaped structure that is long in the front-rear direction. The central axis of the spindle shaft portion 60A coincides with the rotation axis AX. The flange portion 60B extends radially outward from the rear end of the outer circumferential surface of the spindle shaft portion 60A. A spline shape in the axial direction of the rotation axis AX is formed on the periphery of the side surface of the flange portion 60B as the connecting portion 60C. As described above, a spline shape in the axial direction of the rotation axis AX is also formed on the connecting portion 59C of the internal gear 59. The connecting portion 59C of the internal gear 59 and the connecting portion 60C of the spindle 60 are connected by a spline in the axial direction of the rotation axis AX.

[0074] A tip opening 60D is provided at the tip of the spindle shaft portion 60A. The anvil projection 81D of the anvil 81, which will be described later, is inserted into the tip opening 60D.

[0075] The spindle 60 has spindle grooves 61 on the outer circumferential surface of the spindle shaft portion 60A. Three spindle grooves 61 are provided on the outer circumferential surface of the spindle shaft portion 60A. One spindle groove 61 has a central spindle groove portion 61A, a first spindle groove portion 61B, and a second spindle groove portion 61C. The central spindle groove portion 61A is located at the front end of the spindle groove 61. The first spindle groove portion 61B extends from the central spindle groove portion 61A inclined backward toward one side in the circumferential direction. The second spindle groove portion 61C extends from the central spindle groove portion 61A inclined backward toward the other side in the circumferential direction. One ball 62 is placed in each spindle groove 61. Specifically, one ball 62 is placed between the hammer groove 79 of the inner hammer 78, which will be described later, and the spindle groove 61. The rotational force of the spindle 60 is transmitted to the inner hammer 78 via the ball 62. The behavior of the ball 62 and the inner hammer 78 when the spindle 60 rotates will be described later.

[0076] Next, the striking mechanism 70 will be described. The striking mechanism 70 is driven by the motor 40. The rotational force of the motor 40 is transmitted to the striking mechanism 70 via the planetary gear mechanism 50 and the spindle 60. The striking mechanism 70 strikes the anvil 81 in the rotational direction based on the rotational force of the spindle 60, which is rotated by the motor 40. The striking mechanism 70 includes a spiral retaining ring 71, a retainer 72, an outer hammer 73, a ball 73F, a ball 73G, a first coil spring 74, a second coil spring 75, a washer 76, a support coil spring 77, and an inner hammer 78.

[0077] The inner hammer 78 strikes the anvil 81 in a rotational direction around the rotation axis AX. The inner hammer 78 is supported by the spindle 60. The inner hammer 78 is positioned around the spindle shaft portion 60A.

[0078] The inner hammer 78 has a hammer body 78A, a hammer projection 78B, and a hammer groove 79. The hammer body 78A is cylindrical. The hammer body 78A is positioned around the spindle shaft 60A. The hammer projection 78B is provided at the front of the hammer body 78A. The hammer projection 78B protrudes forward from the front of the hammer body 78A. Two hammer projections 78B are provided around the rotation axis AX.

[0079] The hammer body 78A has a plurality of hemispherical recesses 78C along the perimeter of its outer wall. The inner hammer 78 has a plurality of balls 78D. The balls 78D are made of metal. One ball 78D is placed in each recess 78C. More specifically, the plurality of balls 78D are positioned between the inner hammer 78 and the outer hammer 73, and transmit the rotational force of the inner hammer 78 to the outer hammer 73.

[0080] Three hammer grooves 79 are formed in the inner wall of the hammer body 78A. The hammer grooves 79 are narrower at the rear and widen towards the front. Each hammer groove 79 has a central hammer groove portion 79A located at the rear end of the hammer groove 79, a first hammer groove portion 79B extending from the central hammer groove portion 79A to one side in the circumferential direction, and a second hammer groove portion 79C extending from the central hammer groove portion 79A to the other side in the circumferential direction. As described above, one ball 62 is positioned between each of the three spindle grooves 61 and the three hammer grooves 79. The rotational force of the spindle 60 is transmitted to the inner hammer 78 via the balls 62. The behavior of the balls 62 and the inner hammer 78 when the spindle 60 rotates will be described later.

[0081] The outer hammer 73 is positioned around the inner hammer 78. The outer hammer 73 is cylindrical. The outer hammer 73 is positioned to surround the axis of rotation AX. The outer hammer 73 rotates together with the inner hammer 78 in the direction of rotation around the axis of rotation AX. By rotating together with the inner hammer 78, the outer hammer 73 increases the moment of inertia of the striking mechanism 70.

[0082] The outer hammer 73 includes a cylindrical portion 73A, a stepped portion 73B, and a rear end surface portion 73C. The cylindrical portion 73A extends from the front to the rear. The stepped portion 73B is connected to the rear end of the cylindrical portion 73A and has a smaller diameter than the cylindrical portion 73A. The rear end surface portion 73C is connected to the rear end of the stepped portion 73B and is an annular surface that intersects perpendicularly with the rotation axis AX. A circular opening 73D is formed in the rear end surface portion 73C, centered on the rotation axis AX. The spindle shaft portion 60A of the spindle 60 passes through the opening 73D from the rear to the front (Figure 3).

[0083] A retaining groove 73E is formed on the inner surface of the cylindrical portion 73A of the outer hammer 73 to guide the balls 78D in the axial direction. The retaining groove 73E has a groove shape that extends in the axial direction of the rotation axis AX. Multiple retaining grooves 73E are provided at intervals in the circumferential direction on the inner surface of the cylindrical portion 73A. Multiple balls 78D are positioned between the recess 78C of the inner hammer 78 and the retaining groove 73E of the outer hammer 73, and transmit the rotational force of the inner hammer 78 to the outer hammer 73.

[0084] The inner hammer 78 and the outer hammer 73 can move relative to each other in the axial direction of the rotation axis AX. The inner hammer 78 moves axially relative to the outer hammer 73 while being guided by the retaining groove 73E of the outer hammer 73 via the ball 78D.

[0085] The inner hammer 78 and outer hammer 73 are fixed relative to each other in the direction of rotation around the rotation axis AX by a plurality of balls 78D. When rotational force is transmitted from the spindle 60 to the inner hammer 78, the plurality of balls 78D transmit the rotational force of the inner hammer 78 to the outer hammer. The inner hammer 78 and outer hammer 73 rotate together around the rotation axis AX. That is, the inner hammer 78 and outer hammer 73 are movable relative to the axial direction of the rotation axis AX, but are fixed relative to the direction of rotation of the rotation axis AX. As will be described later, the inner hammer 78 moves in the axial direction of the rotation axis AX when the impact tool 1 is driven. Therefore, the inner hammer 78 generates vibration in the axial direction of the rotation axis AX when the impact tool 1 is driven. However, the outer hammer 73 is fixed immovably to the hammer housing 4, and is movable relative to the inner hammer 78 in the axial direction of the rotation axis AX. Therefore, even if the inner hammer 78 vibrates in the axial direction of the rotation axis AX, the outer hammer 73 does not vibrate in the axial direction of the rotation axis AX. As a result, the outer hammer 73 can increase the moment of inertia in the rotational direction around the rotation axis AX without increasing the vibration in the axial direction of the rotation axis AX, thereby increasing the striking force of the striking mechanism 70.

[0086] A spiral retaining ring 71 and a retainer 72 are positioned between the internal gear 59 and the outer hammer 73. The spiral retaining ring 71 is positioned in front of the internal gear 59. The spiral retaining ring 71 is fixed to the inner wall of the hammer housing 4 by an outward biasing force, thereby preventing it from moving in the front-rear direction. The inner diameter of the spiral retaining ring 71 is smaller than the outer diameter of the internal gear 59. Therefore, the spiral retaining ring 71 restricts the forward movement of the internal gear 59.

[0087] A retainer 72 is positioned in front of the spiral retaining ring 71. The inner diameter of the spiral retaining ring 71 is smaller than the outer diameter of the retainer 72. Therefore, the spiral retaining ring 71 restricts the rearward movement of the retainer 72.

[0088] Multiple balls 73F are positioned between the flange portion 60B of the spindle 60, the outer hammer 73, and the rear end surface portion 73C. The rear end surface portion 73C has circular grooves formed therein that movably hold the balls 73F. The balls 73F assist in the relative rotation of the outer hammer 73 with respect to the spindle 60.

[0089] Multiple balls 73G are positioned between the stepped portion 73B of the outer hammer 73 and the retainer 72. The stepped portion 73B and the retainer 72 movably hold the multiple balls 73G. The balls 73G assist in the relative rotation of the outer hammer 73 with respect to the retainer 72.

[0090] Between the front surface of the rear end surface 73C of the outer hammer 73 and the inner hammer 78, a first coil spring 74, a second coil spring 75, a washer 76, and a support coil spring 77 are arranged. The support coil spring 77 biases the second coil spring 75 rearward via the washer 76. The first coil spring 74 and the second coil spring 75 generate a spring force that moves the inner hammer 78 forward. The support coil spring 77 also has a spring force that moves the inner hammer 78 forward, but is mainly positioned to support the second coil spring 75 with a predetermined spring force to prevent it from moving in the front-rear direction. The spring constant of the first coil spring 74 is smaller than the spring constant of the second coil spring 75. The spring constant of the support coil spring 77 is smaller than the spring constant of the first coil spring 74. The springs, in order from smallest to largest spring constant, are the support coil spring 77, the first coil spring 74, and the second coil spring 75. The behavior of the first coil spring 74 and the second coil spring 75 will be described later. This concludes the explanation of the configuration of the striking mechanism 70.

[0091] An anvil 81 is positioned in front of the impact mechanism 70. The anvil 81 is connected to the front end of the spindle 60. The anvil 81 rotates around the rotation axis AX by the inner hammer 78. The anvil 81 is also struck in the rotational direction by the inner hammer 78. The anvil 81 is the output shaft of the impact tool 1, which outputs the rotational force of the motor 40 and the impact force of the impact mechanism 70 to the tip tool.

[0092] The anvil 81 has an anvil shaft portion 81A and an arm portion 81B. The anvil shaft portion 81A is a rod-shaped member that is long in the front-rear direction. The central axis of the anvil shaft portion 81A and the rotation axis AX coincide. The arm portion 81B is a pair of projection members that extend radially outward from the rear end of the anvil shaft portion 81A.

[0093] A tool hole 81C is provided on the front end face of the anvil 81. The tool hole 81C is formed to extend rearward from the front end face of the anvil shaft portion 81A. A tip tool is inserted into the tool hole 81C. A cylindrical anvil projection 81D is provided on the rear end face of the anvil 81, extending from front to rear. The anvil projection 81D is inserted into the tip opening 60D of the spindle 60.

[0094] On the front side of the anvil 81, anvil bearings 84 and 86 are arranged in the front-to-back direction around the anvil shaft portion 81A. The anvil 81 is rotatably supported by anvil bearings 84 and 86. The rotation axis of the anvil 81 coincides with the rotation axis of the inner hammer 78, the rotation axis of the spindle 60, and the rotation axis AX of the motor 40. An O-ring 85 is placed between anvil bearing 84 and the spindle shaft portion 60A. An O-ring 87 is placed between anvil bearing 86 and the spindle shaft portion 60A. Anvil bearings 84 and 86 are held inside the small cylindrical portion 4C of the hammer housing 4. The hammer housing 4 supports the anvil 81 via anvil bearings 84 and 86.

[0095] A spiral retaining ring 82 and a washer 83 are positioned in front of the arm portion 81B. The spiral retaining ring 82 fixes the washer 83 to the hammer housing 4 by an outward biasing force against the inner wall of the hammer housing 4. The spiral retaining ring 82 is positioned so as not to come into contact with the anvil 81. The washer 83 comes into contact with the anvil 81. When the motor 40 is started and the anvil 81 rotates, the washer 83 rotates in response to the rotational force of the anvil 81.

[0096] The tool holding mechanism 88 is positioned around the front of the anvil 81. The tool holding mechanism 88 holds the tip tool inserted into the tool hole 81C of the anvil 81. The tool holding mechanism 88 is detachable from the tip tool. The tool holding mechanism 88 is a well-known technology, so its explanation is omitted.

[0097] [Impact Tools] Next, we will explain the operation of the impact tool 1 when it is started. We will explain using the example of a user performing a screw tightening operation. The user inserts the tip tool (driver bit) to be used for screw tightening into the tool hole 81C of the anvil 81. The tip tool inserted into the tool hole 81C is held by the tool holding mechanism 88. After that, the user operates the forward / reverse rotation switch lever 27 so that the motor 40 rotates in the forward direction.

[0098] The user grasps the grip section 22 and pulls the trigger lever 26 with their fingers. When the trigger lever 26 is pulled, power is supplied from the battery pack 10 to the motor 40, and the motor 40 starts up. When the motor 40 starts up, the rotor shaft 45 of the rotor 44 rotates. When the rotor shaft 45 rotates, the rotational force of the rotor shaft 45 is input to the planetary gear mechanism 50. Specifically, the rotational force of the rotor shaft 45 rotates the pinion gear 58 of the planetary gear mechanism 50. The pinion gear 58 rotates in the same direction as the rotor shaft 45. The pinion gear 58 is aligned with the rear rotor bearing 32 that supports the rotor shaft 45 and the front rotor bearing 33 that supports the pinion gear 58 itself.

[0099] When the pinion gear 58 rotates, the three planetary gears 57 arranged around the pinion gear 58 rotate on their own axis. As described above, the three planetary gears 57 are supported by a carrier 55. The carrier 55 is fixed in place by a carrier fixing member 51 so as not to rotate. Therefore, the planetary gears 57 can rotate on their own axis but do not revolve. Each planetary gear 57 is aligned by a gear shaft pin 56 fixed to the carrier 55.

[0100] The rotation of the three planetary gears 57 causes the internal gear 59 to rotate. When viewed from the direction of the rotation axis AX, the direction of rotation of the pinion gear 58 is opposite to the direction of rotation of the internal gear 59. In other words, the direction of rotation of the rotor 44 of the motor 40 is opposite to the direction of rotation of the internal gear 59.

[0101] The rotational force of the internal gear 59 is transmitted to the spindle 60, which is connected to the internal gear 59 by a spline. The rotational speed of the spindle 60 is lower than the rotational speed of the rotor 44. The rotational direction of the internal gear 59 and the rotational direction of the spindle 60 are the same. That is, the rotational direction of the rotor 44 of the motor 40 is opposite to the rotational direction of the spindle 60.

[0102] The rotational force of the spindle 60 is transmitted to the inner hammer 78 via three balls 62 positioned between three spindle grooves 61 and three hammer grooves 79. The spindle 60 and the inner hammer 78 are biased away from each other by a first coil spring 74, a second coil spring 75, and a support coil spring 77. Therefore, at the start of the impact tool 1, the three balls 62 are localized between the central spindle groove 61A of the spindle 60 and the central hammer groove 79A of the inner hammer 78.

[0103] When the rotational force of the spindle 60 is transmitted to the inner hammer 78 via the three balls 62, the inner hammer 78 rotates. The rotational force of the inner hammer 78 is transmitted to the outer hammer 73 via the ball 78D. The outer hammer 73 rotates at the same rotational speed as the inner hammer 78.

[0104] The inner hammer 78 transmits rotational force to the arm portion 81B of the anvil 81 via the hammer projection 78B. That is, the anvil 81 rotates with the hammer projection 78B and the arm portion 81B in contact. When the spindle 60 rotates (forward) with the hammer projection 78B and the arm portion 81B in contact, the anvil 81 rotates together with the inner hammer 78, the outer hammer 73, and the spindle 60. In this case, the anvil 81 rotates without any impact force being applied from the inner hammer 78 and the outer hammer 73, and the screw tightening operation proceeds.

[0105] This section describes the case where the load on the anvil 81 increases as the screw tightening process progresses, and a striking force is applied to the anvil 81. First, the actions of the first coil spring 74, the second coil spring 75, and the support coil spring 77 are described. The biasing forces of these coil springs act on the striking force that the inner hammer 78 applies to the anvil 81. Note that the spring constant of the support coil spring 77 is very small compared to the first coil spring 74 and the second coil spring 75, so in effect, it is the first coil spring 74 and the second coil spring 75 that act on the striking force that the inner hammer 78 applies to the anvil 81.

[0106] The spring constant of the first coil spring 74 is smaller than the spring constant of the second coil spring 75. When the load on the anvil 81 is small during screw tightening, the biasing force (spring force) of the first coil spring 74 acts on the inner hammer 78. When the load on the anvil 81 is large during screw tightening, the biasing forces (spring forces) of the first coil spring 74 and the second coil spring 75 act on the inner hammer 78.

[0107] The following will explain two cases in which impact force is applied to the anvil 81. The first case will be described when the load acting on the anvil 81 is less than a predetermined value. The second case will be described when the load acting on the anvil 81 is greater than or equal to a predetermined value.

[0108] Let's describe the first case. If a load smaller than a predetermined value is acting on the anvil 81 as the screw tightening operation progresses, the rotation of the anvil 81, inner hammer 78, and outer hammer 73 will stop. With the rotation of the inner hammer 78 and outer hammer 73 stopped, when the spindle 60 rotates, the ball 62 moves backward between the second spindle groove 61C and the second hammer groove 79C, resisting the spring force of the first coil spring 74.

[0109] The inner hammer 78 receives a backward force from the ball 62 and moves backward. As the inner hammer 78 moves backward, contact between the hammer projection 78B and the arm 81B is released. The inner hammer 78, having moved backward, moves forward while rotating due to the spring force of the first coil spring 74. The outer hammer 73 does not move in the front-to-back direction, but rotates together with the inner hammer 78.

[0110] The anvil 81 is struck in the rotational direction by the inner hammer 78. The anvil 81 is subjected to rotational force around the rotation axis AX and impact force in the rotational direction. The inner hammer 78, having struck the anvil 81, moves backward while rotating in the opposite direction due to the impact. As the inner hammer 78 moves backward, contact between the hammer projection 78B and the arm portion 81B is released again. Then, the inner hammer 78 moves forward while rotating due to the spring force of the first coil spring 74 and strikes the anvil 81 again. Through this series of actions, the impact tool 1 can continuously apply impact force and rotational force to the screw.

[0111] Let's explain the second case. If the load on the anvil 81 exceeds a predetermined value as the screw tightening operation progresses, the inner hammer 78 initially behaves the same as in the first case. As the load on the anvil 81 increases, the impact on the inner hammer 78 after striking the anvil 81 also increases. The amount of movement of the anvil 81 as it rotates backward is greater than in the first case. In this case, the inner hammer 78 is subjected to the spring force of the second coil spring 75 in addition to the spring force of the first coil spring 74. The inner hammer 78 rotates forward due to the spring forces of the first coil spring 74 and the second coil spring 75 and strikes the anvil 81. Through this series of actions, the impact tool 1 can apply a stronger impact force and rotational force to the screw than in the first case.

[0112] Impact tool 1 can start impacting when the load is low at the beginning of screw tightening by applying a soft spring (first coil spring 74). Then, when the load increases, a stiff spring (second coil spring 75) is added to the impact, enabling stronger screw tightening. The operation of impact tool 1 has been explained above.

[0113] As described above, in the impact tool 1 of this embodiment, the planetary gear mechanism 50 is configured to operate in a star configuration with the carrier 55 fixed so as not to rotate. When the planetary gear mechanism 50 operates in a star configuration, the rotation direction of the motor 40 and the rotation direction of the internal gear 59 and spindle 60 are opposite. As a result, the moment of inertia due to the rotation of the motor 40 and the moment of inertia due to the rotation of the internal gear 59 and spindle 60 cancel each other out, and the phenomenon of the impact tool 1 being shaken by the moment of inertia at the start and stop of the impact tool 1 can be suppressed. As a result, the burden on the user when working with the impact tool 1 can be reduced, and the usability of the impact tool 1 can be improved.

[0114] In the impact tool 1 of this embodiment, the carrier 55 is fixed to the hammer housing 4 so as not to rotate via the carrier fixing member 51. Therefore, the carrier 55 can be firmly fixed so that the planetary gear 57, which is subjected to a strong rotational force from the motor 40 (pinion gear 58), does not revolve. As a result, the rotational force of the pinion gear 58 can be transmitted to the internal gear 59 without being weakened by the planetary gear 57 and the carrier 55. If the fixing of the carrier 55 is weak, the rotational force from the pinion gear 58 will be absorbed by the planetary gear 57, and the rotational force transmitted to the internal gear 59 will also be weakened. On the other hand, in this embodiment, since the carrier 55 is fixed to the hammer housing 4 so as not to rotate via the carrier fixing member 51, the rotational force of the pinion gear 58 can be efficiently transmitted to the internal gear 59.

[0115] The impact tool 1 of this embodiment is equipped with an inner hammer 78 positioned around the spindle 60 and capable of rotating in the same direction as the spindle 60 by the rotational force of the spindle 60. It also includes an anvil 81, at least a portion of which is positioned in front of the spindle 60 and is struck in the rotational direction by the inner hammer 78. Therefore, by canceling out the moment of inertia due to the rotation of the motor 40 and the moment of inertia due to the rotation of the inner hammer 78, the phenomenon of the impact tool 1 body being shaken in the rotational direction during initial movement and stopping can be suppressed. As a result, the burden on the user during work using the impact tool 1 can be reduced, and the usability of the impact tool 1 can be improved.

[0116] In this embodiment, the internal gear 59 and the spindle 60 are constructed as separate components. Therefore, compared to the case where the internal gear 59 and the spindle 60 are manufactured as a single unit, manufacturing can be simplified. Furthermore, compared to the case where the internal gear 59 and the spindle 60 are formed as a single unit, it becomes easier to use different materials for each component.

[0117] In this embodiment, the internal gear 59 and the spindle 60 are connected so as to be relatively movable in the axial direction of the rotation shafts of the internal gear 59 and the spindle 60. Therefore, when the impact tool 1 is driven, it is possible to suppress the transmission of vibrations in the axial direction of the rotation shaft from the spindle 60 to the internal gear 59. As a result, the durability of the planetary gear mechanism 50 can be improved.

[0118] In this embodiment, the internal gear 59 and the spindle 60 are connected by splines running along the axial direction of the rotation shafts of the internal gear 59 and the spindle 60. Therefore, when the impact tool 1 is driven, it is possible to suppress the transmission of axial vibrations from the rotation shaft of the spindle 60 to the internal gear 59, while simultaneously enabling the transmission of rotational power from the internal gear 59 to the spindle 60, and providing a structure with excellent self-aligning ability.

[0119] In this embodiment, the carrier fixing member 51 has a gear-shaped first locking portion 51B with multiple teeth formed in the circumferential direction around the pinion gear 58. The hammer housing 4 has a second locking portion 4B that engages with the first locking portion 51B. Therefore, since the carrier fixing member 51 is fixed to the hammer housing 4 by its circumferential gear shape, the housing can easily receive the rotational force of the carrier 55. As a result, the carrier 55 can be indirectly and strongly fixed to the hammer housing 4.

[0120] In this embodiment, the carrier 55 is a metal component, and the carrier fixing member 51 is a resin component. Therefore, by making the carrier 55, which receives force from the planetary gear 57, a metal component, the strength of the carrier 55 can be increased, while making the carrier fixing member 51 a resin component can reduce weight.

[0121] The following describes the advantages of this embodiment compared to power tools that use a planetary gear mechanism in a planetary operating mode. In power tools that use a planetary gear mechanism in a planetary operating mode, the carrier and spindle are sometimes formed as a single unit. When the carrier and spindle are formed as a single unit, the manufacturing process is very time-consuming, such as by machining metal materials. Furthermore, in power tools with such a structure, it is necessary to form a hollow gear chamber between the carrier and spindle to house the planetary gears, which makes the structure complex. As a result, the manufacturing process is further complicated.

[0122] On the other hand, in this embodiment, the impact tool 1 can be manufactured by forming the internal gear 59 and the spindle 60 as separate components, thus simplifying manufacturing. Furthermore, it is not necessary to form a hollow gear chamber for arranging the planetary gear, as is the case with conventional power tools. The internal gear itself can serve as the gear chamber for arranging the planetary gear, thus simplifying the structure and reducing costs. In this embodiment, the internal gear 59 has a large opening at the rear, making it easy to manufacture. During the assembly of the impact tool 1, the planetary gear is simply placed from the rear of the internal gear and supported by the gear shaft pin 56, thus simplifying the assembly of the impact tool 1. This also reduces manufacturing costs.

[0123] Furthermore, in the impact tool 1 of this embodiment, a bearing for aligning the spindle 60 is not required. Therefore, the number of parts required to manufacture the impact tool 1 can be reduced, resulting in a simpler structure and lower costs.

[0124] B. Second Embodiment: The impact tool 1a according to the second embodiment will now be described. Figure 9 is an explanatory diagram showing the schematic configuration of the impact tool 1a. The difference between the impact tool 1a and the impact tool 1 is the positional relationship between the axis of rotation of the motor 40 and the axis of rotation of the spindle 60. Hereinafter, the axis of rotation of the motor 40 will be referred to as rotation axis MAX, and the axis of rotation of the spindle 60 will be referred to as rotation axis SAX. In the impact tool 1 of the first embodiment, the rotation axis MAX of the motor 40 and the rotation axis SAX of the spindle 60 are located on the same straight line. On the other hand, in the impact tool 1a of the second embodiment, the rotation axis MAX of the motor 40 and the rotation axis SAX of the spindle 60 are parallel. In the following description, the same reference numerals will be used for mechanisms and components of the impact tool 1a according to the second embodiment that have the same configuration and function as those of the impact tool 1 according to the first embodiment.

[0125] As shown in Figure 9, the impact tool 1a includes a motor 40, a planetary gear mechanism 50, a spindle 60, a striking mechanism 70, a first gear shaft 91, and a second gear shaft 92. Similar to the first embodiment, the planetary gear mechanism 50 in the second embodiment is configured to operate in a star configuration. That is, the pinion gear 58 is rotatable. The planetary gear 57 is rotatable. The carrier 55 supporting the planetary gear 57 is fixed so as not to rotate by a carrier fixing member 51. Since the carrier 55 supporting the planetary gear 57 is fixed so as not to rotate, the planetary gear 57 is rotatable but cannot revolve around the pinion gear 58. The internal gear 59 is rotatable. The configuration of the planetary gear mechanism 50 is the same as in the first embodiment described above, so a detailed explanation is omitted.

[0126] The first gear shaft 91 is fitted into the opening 59B of the internal gear 59. The first gear shaft 91 has a shaft portion 91A, a gear portion 91B, and a connecting portion 91C. The connecting portion 91C is located at the rear end of the shaft portion 91A and has a spline formed on it. The connecting portion 59C of the internal gear 59 and the connecting portion 91C of the first gear shaft 91 are connected by a spline in the axial direction of the rotation axis MAX. Therefore, when the impact tool 1a is driven, it is possible to suppress the transmission of axial vibrations of the rotation axis MAX from the first gear shaft 91 to the internal gear 59, while also providing a structure with excellent ability to transmit rotational power from the internal gear 59 to the first gear shaft 91 and excellent self-aligning ability. The rotation direction of the first gear shaft 91 is the same as that of the internal gear 59. In other words, the direction of rotation of the first gear shaft 91 is opposite to the direction of rotation of the rotor shaft 45.

[0127] The first gear shaft 91 transmits rotational force to the second gear shaft 92. The second gear shaft 92 has a shaft portion 92A, a front end gear portion 92B, and a rear end gear portion 92C. The gear portion 91B of the first gear shaft 91 is located at the front end of the shaft portion 91A and forms a gear. The gear portion 91B of the first gear shaft 91 meshes with the rear end gear portion 92C of the second gear shaft 92. The first gear shaft 91 transmits rotational force to the second gear shaft 92 via the gear portion 91B and the rear end gear portion 92C. Note that the rotation direction of the first gear shaft 91 and the rotation direction of the second gear shaft 92 are opposite.

[0128] The second gear shaft 92 is connected to the spindle 60. The front end gear portion 92B of the second gear shaft 92 meshes with the spindle gear portion 60E of the spindle 60. The rotational force of the second gear shaft 92 is transmitted to the spindle 60 via the front end gear portion 92B and the spindle gear portion 60E. The rotation direction of the spindle 60 is opposite to that of the second gear shaft 92. That is, the rotation direction of the spindle 60 is opposite to that of the rotor shaft 45 (motor 40). The rotation direction of the spindle 60 is the same as that of the internal gear 59 and the first gear shaft 91.

[0129] The manner in which the rotational force of the spindle 60 is transmitted to the striking mechanism 70, the anvil 81, and the cutting tool is the same as in the first embodiment, so a description will be omitted.

[0130] As described above, in the impact tool 1a of this embodiment, the planetary gear mechanism 50 is configured to operate in a star configuration with the carrier 55 fixed so as not to rotate. When the planetary gear mechanism 50 operates in a star configuration, the rotation direction of the motor 40 and the rotation direction of the internal gear 59 are opposite. Furthermore, in the impact tool 1a, the rotational force of the internal gear 59 is transmitted to the spindle 60 via the first gear shaft 91 and the second gear shaft 92. As a result, in the impact tool 1a as well, the rotation direction of the motor 40 and the rotation direction of the internal gear 59 and spindle 60 are opposite, similar to the first embodiment. As a result, the moment of inertia due to the rotation of the motor 40 and the moment of inertia due to the rotation of the internal gear 59 and spindle 60 cancel each other out, and the phenomenon of the impact tool 1a being shaken by the moment of inertia during initial movement and stopping of the impact tool 1a can be suppressed. As a result, the burden on the user when working with the impact tool 1a can be reduced. The usability of the impact tool 1a can be improved.

[0131] Similar to the first embodiment described above, the impact tool 1a of the second embodiment is equipped with an inner hammer 78 positioned around the spindle 60 and capable of rotating in the same direction as the spindle 60 by the rotational force of the spindle 60. It is also equipped with an anvil 81, at least a portion of which is positioned in front of the spindle 60 and is struck in the rotational direction by the inner hammer 78. Therefore, by canceling out the moment of inertia due to the rotation of the motor 40 and the moment of inertia due to the rotation of the inner hammer 78, the phenomenon of the impact tool 1a body being shaken in the rotational direction during initial movement and stopping can be suppressed. As a result, the burden on the user when working with the impact tool 1a can be reduced. The usability of the impact tool 1a can be improved.

[0132] Similar to the first embodiment described above, in the impact tool 1a of the second embodiment, the internal gear 59 and the spindle 60 are configured as separate components. Therefore, compared to the case where the internal gear 59 and the spindle 60 are manufactured as a single unit, manufacturing can be simplified. Furthermore, compared to the case where the internal gear 59 and the spindle 60 are formed as a single unit, it becomes easier to use different materials for each component. In addition, the impact tool 1a according to the second embodiment provides the same effects as the impact tool 1 according to the first embodiment described above.

[0133] The correspondence between each component (feature) of the above embodiments and each component (feature) of the present disclosure or invention is shown below. However, each component of the embodiments is merely an example and does not limit each component of the present disclosure or invention.

[0134] Impact tool 1 and impact tool 1a are examples of "power tools". Motor 40 is an example of a "motor". Spindle 60 is an example of a "spindle". Planetary gear mechanism 50 is an example of a "planetary gear mechanism". Pinion gear 58 is an example of a "sun gear". Planetary gear 57 is an example of a "planetary gear". Internal gear 59 is an example of an "internal gear". Carrier 55 is an example of a "carrier". Carrier fixing member 51 is an example of a "carrier fixing member". Hammer housing 4 is an example of a "housing". The splines formed on connection part 59C and connection part 60C are examples of "splines". First locking part 51B is an example of a "first locking part". Second locking part 4B is an example of a "second locking part". Inner hammer 78 is an example of a "hammer". Anvil 81 is an example of an "anvil".

[0135] The above embodiments are merely illustrative, and the power tools relating to this disclosure are not limited to the exemplified impact tool 1 and impact tool 1a. For example, non-limiting modifications as exemplified below can be made. Furthermore, at least one of these modifications may be adopted in combination with the impact tool 1 and impact tool 1a exemplified in the embodiments, and any of the inventions described in each claim.

[0136] For example, power tools are not limited to impact tools; various power tools can be used as long as the motor's rotation axis and the spindle's rotation axis are arranged parallel or on the same line, such as drill drivers and drills. Similarly, impact tools can be various power tools that apply impact in the direction of the spindle's rotation, such as impact drivers and impact wrenches.

[0137] The carrier 55 only needs to be fixed so as not to rotate, and does not need to be fixed by the carrier fixing member 51. For example, the carrier 55 itself may be shaped to be fixed to an external housing.

[0138] The internal gear 59 and the spindle 60 do not necessarily have to be constructed as separate components. A configuration in which the internal gear 59 and the spindle 60 are formed as a single unit is also possible. For example, the internal gear 59 and the spindle 60 may be manufactured as a single unit by machining a metal material. This increases the rigidity of the internal gear 59 and the spindle 60.

[0139] The connection between the internal gear 59 and the spindle 60 is not limited to a spline. Other configurations may be used as long as the internal gear 59 and the spindle 60 are connected in a manner that allows relative movement in the axial direction of their respective rotational shafts. For example, connections using keyways or connections using hexagonal protrusions and recesses can be employed.

[0140] The carrier fixing member 51 is not limited to being made of a resin material. The carrier fixing member 51 may be made of a metal material. [Explanation of symbols]

[0141] 1, 1a: Impact tool, 2: Main housing, 2S: Screw, 3: Rear cover, 4: Hammer housing, 4B: Second locking part, 4C: Small cylinder part, 10: Battery pack, 21: Motor housing, 22: Grip part, 23: Battery holder, 24: Air intake, 25: Exhaust port, 26: Trigger lever, 27: Forward / reverse rotation switch lever, 28: Battery mounting part, 29: Controller, 31: Fan, 32: Rear rotor bearing, 33: Front rotor bearing, 40: Motor, 41: Stator, 42: Stator core, 43: Coil, 44: Rotor, 45: Rotor shaft, 46: Rotor core, 47: Rotor magnet, 48: Sensor magnet, 49: Sensor substrate, 50: Planetary gear mechanism, 51: Carrier fixing member, 51A: Holding part, 51B: First locking part, 53: O-ring, 55: Carrier, 55A: Opening, 55B: Bearing fixing part, 56: Gear shaft pin, 57: Planetary gear, 58: Pinion gear, 59: Internal gear, 59A: Inner wall, 59B: Opening, 59C: Connection part, 60: Spindle, 60A: Spindle shaft part, 60B: Flange part, 60C: Connection part, 60D: Tip opening, 60E: Spindle gear part, 61: Spindle groove, 61A: Central spindle groove section, 61B: First spindle groove section, 61C: Second spindle groove section, 62: Ball, 70: Striking mechanism, 71: Spiral retaining ring, 72: Retainer, 73: Outer hammer, 73A: Cylindrical section, 73B: Stepped section, 73C: Rear end surface section, 73D: Opening, 73E: Retaining groove, 73F: Ball, 73G: Ball, 74: First coil spring, 75: Second coil spring, 76: Washer, 77: Support coil spring, 78: Inner hammer, 78A: Hammer body section, 78B: Hammer projection section, 78C: Recess, 78 D: Ball, 79: Hammer groove, 79A: Central hammer groove, 79B: First hammer groove, 79C: Second hammer groove, 81: Anvil, 81A: Anvil shaft, 81B: Arm, 81C: Tool hole, 81D: Anvil projection, 82: Spiral retaining ring, 83: Washer, 84: Anvil bearing, 85: O-ring, 86: Anvil bearing, 87: O-ring, 88: Tool holding mechanism, 91: First gear shaft, 91A: Shaft section, 91B: Gear section, 91C: Connection section, 92: Second gear shaft, 92A: Shaft section, 92B: Front end gear section,92C: Rear end gear section, AX: Rotating shaft, MAX: Rotating shaft, SAX: Rotating shaft,

Claims

1. It is a power tool, Motor and, A spindle that rotates due to the rotational force transmitted from the motor, A planetary gear mechanism that transmits the rotational force of the motor to the spindle, Equipped with, The rotation axis of the motor and the rotation axis of the spindle are arranged on the same straight line. The aforementioned planetary gear mechanism is, A sun gear to which the rotational force from the motor is input, Multiple planetary gears arranged radially outward from the rotation axis of the aforementioned sun gear, A carrier which is fixed to the sun gear in a way that prevents it from rotating, and which supports the plurality of planetary gears so that they can rotate, The plurality of planetary gears are rotatably arranged radially outward from the plurality of planetary gears and have an internal gear that transmits rotational force to the spindle. A power tool characterized by the following features.

2. The power tool according to claim 1, A housing that houses at least a part of the planetary gear mechanism, A carrier fixing member that fixes the carrier to the housing in a way that prevents it from rotating, A power tool characterized by having the following features.

3. A power tool according to claim 1 or claim 2, A power tool characterized in that the internal gear and the spindle are configured as separate components.

4. A power tool according to any one of claims 1 to 3, The power tool is characterized in that the internal gear and the spindle are connected so as to be movable relative to each other in the axial direction of the rotation axis of the internal gear and the spindle.

5. A power tool according to any one of claims 1 to 4, The power tool is characterized in that the internal gear and the spindle are connected by splines in the axial direction of the rotation axis of the internal gear and the spindle.

6. A power tool according to any one of claims 3 to 5, which is dependent on claim 2, The carrier fixing member has a first locking portion which is gear-shaped and has a plurality of teeth formed in the circumferential direction around the rotation axis of the sun gear, The housing has a second locking portion that engages with the first locking portion. A power tool characterized by the following features.

7. A power tool according to any one of claims 3 to 6, which is dependent on claim 2, The carrier is a metal component, The carrier fixing member is made of resin. A power tool characterized by the following features.

8. A power tool according to any one of claims 1 to 7, A hammer positioned around the spindle and capable of rotating in the same direction as the spindle by the rotational force of the spindle, The system comprises an anvil, at least a portion of which is positioned in front of the spindle and which is struck in the rotational direction by the hammer. A power tool characterized by the following features.

9. It is a power tool, Motor and, A spindle that rotates due to the rotational force transmitted from the motor, Equipped with, The rotation axis of the motor and the rotation axis of the spindle are arranged parallel to or on the same straight line. The rotation direction of the motor and the rotation direction of the spindle are opposite. A power tool characterized by the following features.

10. The power tool according to claim 9, The motor is equipped with a planetary gear mechanism that transmits the rotational force of the motor to the spindle, The aforementioned planetary gear mechanism is It comprises a sun gear, a planetary gear, a carrier that supports the planetary gear so that it can rotate, and an internal gear. The rotational force of the motor is input to the sun gear. The carrier is fixed in a way that prevents it from rotating. The aforementioned internal gear is rotatable, The rotational force of the internal gear is output to the spindle. A power tool characterized by the following features.

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