JP7464112B2 - Power Tools - Google Patents

Description

The present invention relates to a power tool.

In the impact drill (power tool) described in the following Patent Document 1, a tool tip is attached to the tip of the impact drill, and a motor is housed inside the impact drill. The rotational force of the motor is then transmitted to the tool tip to perform processes such as drilling holes in the workpiece.

The rear end of the motor's rotating shaft is rotatably supported by a bearing, which is held in a housing. An air intake is formed in the housing near the area that holds the bearing, allowing air to flow into the housing through the air intake.

JP 2007-15062 A

In recent years, there has been a trend for motors to rotate at higher speeds in power tools such as impact drills in order to increase output. This causes the temperature of the bearings that support the motor's rotating shaft to rise. For this reason, it is desirable for power tools to have a structure that can cool the bearings.

In consideration of the above facts, the present invention aims to provide a power tool capable of cooling bearings.

One or more embodiments of the present invention are a power tool comprising a housing that accommodates a motor, a bearing that rotatably supports a rotating shaft of the motor or a drive shaft driven by rotation of the motor, a communication hole formed radially outward of the bearing of the housing and communicating between the inside and outside of the housing, and a bearing retaining portion provided in the housing, formed in a bottomed cylindrical shape, and accommodating the bearing therein, wherein the bearing retaining portion has a side wall that retains an outer peripheral surface of the bearing, and the side wall is formed with an exposure portion that exposes only a front portion of the outer peripheral surface of the bearing radially outward to the air passage of air flowing through the communication hole .
One or more embodiments of the present invention are a power tool comprising a housing that accommodates a motor, a bearing that rotatably supports a rotating shaft of the motor or a drive shaft driven by rotation of the motor, a communication hole formed radially outside the bearing of the housing and communicating between the inside and outside of the housing, and a bearing retaining portion provided in the housing, formed in a bottomed cylindrical shape, and accommodating the bearing therein, wherein the bearing retaining portion has a side wall that retains an outer peripheral surface of the bearing, and the side wall is formed with an exposure portion that exposes only a circumferential portion of a front part of the outer peripheral surface of the bearing to the air passage flowing through the communication hole.
One or more embodiments of the present invention are a power tool comprising a housing that accommodates a motor, a bearing that rotatably supports a rotating shaft of the motor or a drive shaft driven by rotation of the motor, a communication hole formed radially outside the bearing of the housing and communicating between the inside and outside of the housing, and a bearing retaining portion provided in the housing, formed in a bottomed cylindrical shape, and accommodating the bearing therein, wherein the bearing retaining portion has a side wall that holds the outer peripheral surface of the bearing, and an exposed portion is formed in the side wall that exposes a part of the bearing to an air path for air flowing through the communication hole, and the communication holes are arranged in a row in the circumferential direction of the bearing retaining portion, and the exposed portions are each formed radially inward of every other communicating hole in the circumferential direction of the bearing retaining portion.

One or more embodiments of the present invention are directed to a power tool , wherein the communication hole is formed in the bearing holder.

One or more embodiments of the present invention are directed to a power tool in which the exposed portion is configured to expose only a portion of a front portion of the outer circumferential surface of the bearing to the air passage side.

One or more embodiments of the present invention are a power tool in which the exposed portion is configured as a groove portion that connects the communicating hole with the interior of the bearing retaining portion and extends in the axial direction of the bearing retaining portion, a plurality of the communicating holes are arranged in a line circumferentially of the bearing retaining portion, and a plurality of the groove portions are formed radially inward of every other communicating hole in the circumferential direction of the bearing retaining portion.

One or more embodiments of the present invention are a power tool in which the bearing is covered by the housing from one axial side and by a sealing member from the other axial side.

One or more embodiments of the present invention are a power tool in which the sealing member is fixed to the rotating shaft so as to rotate integrally therewith.

One or more embodiments of the present invention are a power tool in which the sealing member has a wing portion formed thereon, and the wing portion generates an air flow radially outwardly of the rotating shaft.

One or more embodiments of the present invention are a power tool in which a fan is provided on the other axial side of the rotating shaft, and the housing is formed with an exhaust hole for outletting the air flow generated by the fan.

In one or more embodiments of the present invention, the housing is a power tool comprising a motor housing that accommodates the motor and a handle housing having a pair of cover members that sandwich the motor housing.

One or more embodiments of the present invention are a power tool in which the housing accommodates a drive mechanism that transmits the driving force of the motor to the tool tip, and the drive mechanism is configured to be switchable between a first mode in which a rotational force is applied to the tool tip, and a second mode in which a rotational force and an impact force are applied to the tool tip.

In one or more embodiments of the present invention, the motor is a power tool driven by a battery pack that is detachable from the housing.

In accordance with one or more embodiments of the present invention, the bearings can be cooled.

FIG. 2 is a side view of the impact drill according to the embodiment, as viewed from the right side. 2 is a side cross-sectional view showing the inside of the impact drill shown in FIG. 1 as viewed from the right side. 2 is a perspective view showing a handle housing and a motor housing of the housing shown in FIG. 1 in an exploded state, as viewed obliquely from the left rear. FIG. 2 is a rear view of the impact drill shown in FIG. 1 as seen from the rear side of the motor housing. FIG. 5 is a cross-sectional view of the bearing holder shown in FIG. 4 taken at the location of a first air intake hole (cross-sectional view taken along line 5-5 in FIG. 4). 6 is a cross-sectional view of the bearing holder shown in FIG. 4 taken at the location of a second air intake hole (cross-sectional view taken along line 6-6 in FIG. 4). 6 is an exploded perspective view showing the bearing holder, the rear motor bearing, the dust seal, and the rotating shaft shown in FIG. 5 in an exploded state, as viewed obliquely from the front right side. FIG.

The following describes the impact drill 10 as a "power tool" according to this embodiment, with reference to the drawings. Note that the arrows UP, FR, and RH, as appropriate shown in the drawings, indicate the upper side, front side, and right side of the impact drill 10, respectively. In the following description, when the up-down, front-back, and left-right directions are used, they refer to the up-down, front-back, and left-right directions of the impact drill 10, unless otherwise specified.

The impact drill 10 is configured as a tool for performing processes such as drilling holes in a workpiece. As shown in Figures 1 and 2, the impact drill 10 includes a housing 20, a motor 40 housed in the housing 20, a drive mechanism 50 driven by the driving force of the motor 40, a battery pack 70, and a control unit 72 that drives and controls the motor 40.

The impact drill 10 also has an operation knob 38. The operation knob 38 is exposed to the outside of the impact drill 10 so that it can be slid left and right. The operation knob 38 is configured to be operated to switch the operation mode of the impact drill 10. Specifically, the operation knob 38 is slid to the left to be placed in the drill mode position, which is set to a drill mode as a "first mode" in which the tip tool T rotates. On the other hand, the operation knob 38 is slid to the right to be placed in the impact drill mode position, which is set to a vibration drill mode as a "second mode" in which the tip tool T rotates and reciprocates in the forward and backward directions. Furthermore, the impact drill 10 has a bearing cooling structure S, and the bearing cooling structure S is applied to the rear motor bearing 45 that rotatably supports the rotating shaft 41 of the motor 40. Each configuration of the impact drill 10 will be described below.

<About the housing 20> The housing 20 forms the outer shell of the impact drill 10. The housing 20 is composed of a handle housing 22 that forms the rear of the housing 20, a motor housing 24 that forms the middle part of the housing 20 in the front-to-rear direction, and a gear housing 28 that forms the front of the housing 20.

<Regarding the handle housing 22> As shown in Figures 1 to 4, the handle housing 22 is formed in a roughly P-shape when viewed from the right side. The handle housing 22 is divided into two parts in the left-right direction, and the handle housing 22 is formed by assembling the two divided cover members 23 together.

The rear end of the handle housing 22 is configured as a handle portion 22A that is gripped by the operator, and the handle portion 22A extends in the vertical direction. In addition, a circular exposure hole 22B is formed in the front of the handle housing 22 in the front-rear direction on the front side of the handle portion 22A to expose a bearing holder 26 of the motor housing 24, which will be described later.

1 and 2, a trigger 33 is provided at the upper end of the handle portion 22A. The handle housing 22 is also provided with a switch button 34 above the trigger 33 for switching the rotation direction of the motor 40, which will be described later. The handle housing 22 is also provided with a switch mechanism 35 behind the trigger 33. The switch mechanism 35 has a switch (not shown) that is operated by the trigger 33 and the switch button 34. The switch is electrically connected to the control unit 72, which will be described later, and is configured to output an output signal to the control unit 72 according to the operation state of the trigger 33 and the switching state of the switch button 34. The handle housing 22 is also provided with a speed change switch 36 below the exposure hole 22B. The speed change switch 36 is configured as a switch that switches the rotation speed of the motor 40, which will be described later, between multiple stages when operated, and is electrically connected to the control unit 72, which will be described later.

The lower end of the handle housing 22 is configured as a battery mounting section 22C for mounting the battery pack 70 described later, and the battery mounting section 22C is formed in a concave shape that is open to the front and bottom in a side view. The battery mounting section 22C is provided with a connector 37 that connects to the battery pack 70 described later.

<Regarding the motor housing 24> As shown in Figures 1 to 4, the motor housing 24 is formed in a generally bottomed cylindrical shape that is open to the front. The motor housing 24 is positioned on the front side of the upper part of the handle housing 22 and is connected to a pair of separated cover members 23 while being sandwiched in the left-right direction between the cover members 23. Specifically, the motor housing 24 is fastened together with one cover member 23 to the other cover member 23. When the handle housing 22 and the motor housing 24 are connected, the vertical middle parts of the left and right sides of the motor housing 24 are exposed to the outside.

The motor housing 24 has a bearing retaining portion 26, which constitutes the center of the bottom of the motor housing 24. The bearing retaining portion 26 is formed in a bottomed cylindrical shape that is open to the front. The bearing retaining portion 26 also constitutes a bearing cooling structure S, which will be described later, and details of the bearing retaining portion 26 will be described later. The motor housing 24 has four arm portions 24A, which extend radially outward from the bearing retaining portion 26 and are connected to the side wall of the motor housing 24. The four arm portions 24A are also arranged every 90 degrees (equally spaced) in the circumferential direction of the bearing retaining portion 26.

<Regarding the gear housing 28> As shown in Figures 1 and 2, the gear housing 28 is configured to include a first gear housing 29 that constitutes the rear part of the gear housing 28, and a second gear housing 30 that constitutes the front part of the gear housing 28. The first gear housing 29 is formed in a cylindrical shape with the axial direction being the front-to-rear direction, and the second gear housing 30 is formed in a concave shape that is open to the rear side. The first gear housing 29 and the second gear housing 30 are fastened and fixed to the motor housing 24 so as to close the front opening of the motor housing 24. A housing tube portion 30A is formed on the upper part of the second gear housing 30, and the housing tube portion 30A is formed in a cylindrical shape with the axial direction being the front-to-rear direction and protrudes forward from the second gear housing 30.

In addition, exhaust sections 31 are formed on the left and right sides between the motor housing 24 and the first gear housing 29, and multiple exhaust holes 31A are formed in the exhaust section 31, connecting the inside and outside of the housing 20. Furthermore, an operation knob 38 is provided on the upper end of the first gear housing 29 so as to be slidable in the left and right direction, and the operation knob 38 is exposed to the outside of the housing 20.

<Regarding the motor 40> As shown in Figure 2, the motor 40 is housed inside the motor housing 24. The motor 40 is configured to include a rotating shaft 41, a rotor 42, and a stator 43.

The rotating shaft 41 is arranged coaxially with the bearing holder 26, with the front-to-rear direction being the axial direction. The rear end (one axial end) of the rotating shaft 41 is rotatably supported by a rear motor bearing 45, which serves as a "bearing", held in the bearing holder 26 of the motor housing 24. Meanwhile, the front end (the other axial end) of the rotating shaft 41 is rotatably supported by a front motor bearing 46, which is held in the first gear housing 29.

The rotor 42 is disposed radially outward of the rotating shaft 41 and is configured to rotate integrally with the rotating shaft 41. The stator 43 is formed in a generally cylindrical shape with its axial direction extending in the front-to-rear direction, and is supported by the motor housing 24 radially outward of the rotor 42. The stator 43 has a stator holder, and a stator coil is wound around the stator holder. The stator coil is connected to the control unit 72, which will be described later. This results in a configuration in which the motor 40 is driven by the control of the control unit 72.

A fan 47 is provided at the front end portion of the rotating shaft 41, rearward of the front motor bearing 46, so as to be able to rotate integrally with the rotating shaft 41. The fan 47 is configured as a centrifugal fan, and is disposed radially inward of the exhaust section 31. The fan 47 is configured to generate an air flow from the rear to the front, and to direct the air flow radially outward of the fan 47. Thus, air is caused to flow into the motor housing 24 through the intake hole 26D of the bearing holding section 26, which will be described later, and the air is discharged from the exhaust hole 31A. This allows the motor 40 to be cooled.

In addition, the front end of the rotating shaft 41 is accommodated within the first gear housing 29, and a pinion gear 41A is formed at the front end of the rotating shaft 41.

<Regarding the drive mechanism 50> The drive mechanism 50 has a spindle 51. The spindle 51 is formed in a generally cylindrical shape with the axial direction being the front-to-rear direction, and is disposed within the upper portion of the gear housing 28. Specifically, the spindle 51 is disposed coaxially with the housing cylinder portion 30A of the second gear housing 30. The front end portion of the spindle 51 is rotatably supported by a front spindle bearing 52 fixed to the second gear housing 30, and the rear end portion of the spindle 51 is rotatably supported by a rear spindle bearing 53 fixed to the first gear housing 29. The spindle 51 is supported by the front spindle bearing 52 and the rear spindle bearing 53 so as to be movable relative to each other in the front-to-rear direction.

The front end of the spindle 51 protrudes forward beyond the housing tube portion 30A. A drill chuck 54 is fastened and fixed to the front end of the spindle 51, and a tool tip T is attached to the drill chuck 54. A recess 51A that is open to the rear is formed at the rear end of the spindle 51, and a steel ball 55 is provided in the recess 51A.

A mode switching shaft 56 is provided on the rear side of the spindle 51. The mode switching shaft 56 has an axial direction in the up-down direction and is formed in a substantially D-shaped cross section. That is, the outer peripheral surface of the mode switching shaft 56 is configured to include a flat portion and a curved portion. The mode switching shaft 56 is connected to the operation knob 38, and the operation knob 38 is slid to rotate the mode switching shaft 56 around its own axis. Specifically, in the drill mode position of the operation knob 38, the curved portion of the mode switching shaft 56 is disposed adjacent to the rear side of the steel ball 55, and in the vibration drill mode position of the operation knob 38, the flat portion of the mode switching shaft 56 is disposed behind the steel ball 55 with a predetermined gap therebetween. As a result, in the drill mode of the vibration drill 10, the movement of the spindle 51 from the initial position (the position shown in FIG. 2) to the rear side is restricted, and in the vibration drill mode of the vibration drill 10, the movement of the spindle 51 from the initial position to the rear side is permitted.

A drive gear 57 is provided at the rear end of the spindle 51 so as to rotate integrally with it. The drive gear 57 is connected to the pinion gear 41A of the rotating shaft 41 of the motor 40 by a two-stage gear 58. As a result, when the motor 40 is driven, the rotational force of the motor 40 is transmitted to the spindle 51, and the spindle 51 and the tool tip T rotate around the axis of the spindle 51.

Furthermore, a first ratchet 59 is provided on the spindle 51 so as to be able to rotate integrally therewith, and the first ratchet 59 is disposed adjacent to the rear side of the front spindle bearing 52. Furthermore, a second ratchet 60 is provided on the rear side of the first ratchet 59. The second ratchet 60 is disposed radially outward of the spindle 51 and is fixed to the second gear housing 30. Furthermore, a biasing spring 61 is provided on the front side of the second ratchet 60, and the spindle 51 is biased forward by the biasing force of the biasing spring 61 and disposed in the initial position. Then, in the initial position of the spindle 51, the second ratchet 60 is disposed rearward of the first ratchet 59 with a predetermined gap therebetween.

Ratchet teeth are formed on the rear surface of the first ratchet 59 and the front surface of the second ratchet 60. In the impact drill mode, the spindle 51 is moved rearward against the biasing force of the biasing spring 61, so that it comes into contact with the ratchet teeth of the first ratchet 59 and the ratchet teeth of the second ratchet 60. As a result, when the spindle 51 rotates, the ratchet teeth of the first ratchet 59 ride over the ratchet teeth of the second ratchet 60, causing the spindle 51 to move back and forth in the front-to-rear direction.

<Battery Pack 70> The battery pack 70 is formed into a substantially rectangular parallelepiped. The battery pack 70 is detachably attached to the battery mounting portion 22C of the handle housing 22 from the front side. The battery pack 70 has a connector (not shown), and when the battery pack 70 is attached to the battery mounting portion 22C, the connector is connected to the connector 37, and power is supplied from the battery pack 70 to the control unit 72 described below. The battery pack 70 also has a pair of locking members 70A (see FIG. 1), which are provided on the left and right sides of the battery pack 70. When the battery pack 70 is attached to the battery mounting portion 16B, the locking members 70A engage with the handle housing 22, restricting the forward movement of the battery pack 70.

<Regarding the control unit 72> The control unit 72 is disposed within the lower end of the handle housing 22. The control unit 72 is electrically connected to the switch of the switch mechanism 35, the speed change switch 36, and the battery pack 70 described above. When the trigger 33 is pulled, the motor 40 is driven by the control unit 72, and the driving force of the motor 40 is transmitted to the tool tip T by the drive mechanism unit 50. When the motor 40 is driven by the control unit 72, the direction of rotation of the motor 40 is set according to the switching state of the switch button 34, and the motor 40 rotates at a rotation speed according to the operating position of the speed change switch 36.

<Regarding the bearing cooling structure S>As shown in Figures 4 to 7, the bearing cooling structure S is composed of a bearing retaining portion 26 of the motor housing 24, a rear motor bearing 45 held by the bearing retaining portion 26, and a dust seal 80 as a "sealing member" provided on the rotating shaft 41 of the motor 40.

<Regarding the bearing retaining portion 26> The bearing retaining portion 26 is formed as a generally bottomed cylinder that is open to the front as a whole. Specifically, the bearing retaining portion 26 includes a generally disk-shaped bottom wall 26A whose thickness direction is in the front-to-rear direction, and a cylindrical side wall 26B that extends forward from the outer periphery of the bottom wall 26A. The interior of the bearing retaining portion 26 is configured as a bearing accommodating portion 26C that accommodates the rear motor bearing 45.

The side wall 26B is provided with a plurality of (eight in this embodiment) "communicating holes" that function as intake holes 26D. When viewed from the front-rear direction, the intake holes 26D are formed as elongated holes curved along the circumferential direction of the bearing holder 26, and are arranged at equal intervals around the bearing holder 26. The interior of the intake holes 26D is configured as an air inlet passage 26E. The intake holes 26D are divided into four first intake holes 26D1 and four second intake holes 26D2, and the first intake holes 26D1 and the second intake holes 26D2 are arranged alternately around the circumferential direction of the bearing holder 26.

A communication groove 26F is formed in the side wall 26B as an "exposed portion" and a "groove portion" on the radial inside of the first air intake hole 26D1. That is, four communication grooves 26F are formed in the side wall 26B. The communication grooves 26F extend in the front-rear direction, are open to the front side, and penetrate the bearing holding portion 26 in the radial direction. As a result, the interior of the first air intake hole 26D1 (air inlet passage 26E) and the bearing accommodating portion 26C are connected by the communication groove 26F. In addition, the bottom of the communication groove 26F is located in the middle of the side wall 26B in the front-rear direction.

<Regarding the rear motor bearing 45> The rear motor bearing 45 is configured as a ball bearing. That is, the rear motor bearing 45 is arranged to include an inner ring 45A that constitutes the radially inner portion of the rear motor bearing 45, an outer ring 45B that constitutes the radially outer portion of the rear motor bearing 45, and balls 45C arranged between the inner ring 45A and the outer ring 45B. The rear motor bearing 45 is fitted into the bearing accommodating portion 26C of the bearing holder 26 and held by the bearing holder 26. The rotating shaft 41 of the motor 40 described above is fitted into the rear motor bearing 45 and is rotatably supported by the rear motor bearing 45.

When the rear motor bearing 45 is held in the bearing holder 26, a portion of the front of the outer ring 45B of the rear motor bearing 45 is exposed radially outward (toward the air inlet passage 26E of the first air intake hole 26D1) by the communicating groove 26F. Meanwhile, the rear of the outer ring 45B is held over the entire circumferential circumference by the side wall 26B of the bearing holder 26. Also, when the rear motor bearing 45 is held in the bearing holder 26, the rear side (one axial side) of the rear motor bearing 45 is covered by the bottom wall 26A of the bearing holder 26. Note that although the cooling of the rear motor bearing has been described as an example of a bearing cooling structure, the present invention can be applied to any bearing provided in a power tool.

<About the dust seal 80> The dust seal 80 is formed in a generally annular plate shape with the plate thickness direction being in the front-to-rear direction. The dust seal 80 is disposed close to the front side of the rear motor bearing 45 and is fixed to the rotating shaft 41 of the motor 40 so as to be rotatable integrally therewith. Specifically, the dust seal 80 covers the rear motor bearing 45 from the front side (the other axial side) with a small gap provided between the rear motor bearing 45 and the dust seal 80 in the front-to-rear direction. Therefore, the dust seal 80 is configured to function as a sealing member for the rear motor bearing 45.

Furthermore, a blade portion 80A is provided on the outer periphery of the dust seal 80. The blade portion 80A is formed in a ring shape when viewed from the front-rear direction, and protrudes forward from the dust seal 80. Furthermore, the blade portion 80A is formed with a plurality of protrusions 80B (eight in this embodiment). The protrusions 80B protrude radially outward from the blade portion 80A, and are arranged at equal intervals around the circumference of the dust seal 80. When the dust seal 80 rotates together with the rotating shaft 41, the blade portion 80A generates an air flow AR2 (see FIG. 5) that flows radially outward from the dust seal 80. In other words, the dust seal 80 is configured to function as a centrifugal fan.

(Function and effect) Next, the function and effect of the impact drill 10 of this embodiment will be explained.

In the impact drill 10 configured as described above, when the trigger 33 is pulled, the motor 40 is driven by the control unit 72, and the tip tool T rotates together with the spindle 51. This allows the workpiece to be drilled. In the impact drill mode of the impact drill 10, the tip tool T is pressed against the workpiece, causing the spindle 51 to move rearward from the initial position. As a result, the ratchet teeth of the first ratchet 59 overcome the ratchet teeth of the second ratchet 60, causing the spindle 51 and the tip tool T to move back and forth while rotating. Therefore, in the impact drill mode, the workpiece can be drilled while applying a rotational force and an impact force.

Here, in the impact drill 10, the rear motor bearing 45, which rotatably supports the rotating shaft 41 of the motor 40, is held in the bearing holder 26 of the motor housing 24. A plurality of air intake holes 26D are formed through the bearing holder 26, and the inside and outside of the motor housing 24 are connected by the air intake holes 26D. A portion of the rear motor bearing 45 is exposed to the air inflow passage 26E inside the air intake holes 26D. This allows the rear motor bearing 45 to be cooled by the air flow AR1 (see FIG. 5) that flows from the air intake holes 26D into the inside of the motor housing 24.

The bearing retaining portion 26 is formed in a cylindrical shape with a bottom that is open to the front. The interior of the bearing retaining portion 26 is configured as a bearing accommodating portion 26C for accommodating the rear motor bearing 45. A plurality of air intake holes 26D are formed penetrating the side wall 26B of the bearing retaining portion 26 in the front-rear direction, and a communication groove 26F is formed that communicates between the air inflow passage 26E and the bearing accommodating portion 26C. This makes it possible to expose a portion of the rear motor bearing 45 to the air inflow passage 26E side of the air intake hole 26D with a simple configuration.

In addition, a plurality of intake holes 26D are formed in the circumferential direction of the bearing holder 26, and the communication groove 26F is formed radially inward of every other intake hole 26D of the intake holes 26D arranged in the circumferential direction. Specifically, the communication groove 26F is formed radially inward of the first intake hole 26D1 in the intake hole 26D. As a result, the rear motor bearing 45 can be cooled by the air flow AR1 flowing into the motor housing 24 from the first intake hole 26D1, while the bearing holder 26 can be cooled by the air flow AR1 flowing into the motor housing 24 from the second intake hole 26D2. As a result, for example, the thermal expansion of the bearing holder 26 during operation of the impact drill 10 can be suppressed. Therefore, the rear motor bearing 45 can be cooled while maintaining the bearing holder 26 in a good holding state to the rear motor bearing 45.

Furthermore, the communication groove 26F is open to the front, and the bottom of the communication groove 26F is located in the fore-and-aft middle part (axial middle part) of the side wall 26B. Therefore, a part of the front part of the rear motor bearing 45 is exposed to the air inlet passage 26E by the communication groove 26F, while the rear part of the rear motor bearing 45 is held over the entire circumferential direction by the side wall 26B. This makes it possible to cool the rear motor bearing 45 while maintaining the bearing holding portion 26 holding the rear motor bearing 45 in an even better state.

In addition, a dust seal 80 is provided on the front side of the rear motor bearing 45, and the rear motor bearing 45 is covered from the front side by the dust seal 80. Furthermore, the rear motor bearing 45 is covered from the rear side by the bottom wall 26A of the bearing retaining portion 26. As a result, the rear motor bearing 45 is sealed from both axial sides by the dust seal 80 and the bearing retaining portion 26. Therefore, the rear motor bearing 45 can be cooled while ensuring dustproofness of the rear motor bearing 45.

The dust seal 80 is also arranged to be rotatable integrally with the rotating shaft 41 of the motor 40. Therefore, when the rotating shaft 41 rotates, an air flow AR2 can be generated that flows radially outward from the dust seal 80. This allows the rear motor bearing 45 to be cooled by the air flow AR1 in the air inlet passage 26E, while the dust in the air flow AR1 can be blown radially outward from the rear motor bearing 45 (in the direction away from the rear motor bearing 45) by the air flow AR2. Therefore, the rear motor bearing 45 can be cooled while improving the dustproofness of the rear motor bearing 45.

Furthermore, the dust seal 80 is formed with a vane portion 80A, which generates an air flow AR2 that flows radially outward from the rotating shaft 41. This allows dust in the air flow AR1 to be effectively blown radially outward from the rear motor bearing 45 by the air flow AR2. Therefore, the dustproofness of the rear motor bearing 45 can be effectively improved while cooling the rear motor bearing 45.

Furthermore, a fan 47 is provided at the front end portion of the rotating shaft 41 so as to be able to rotate integrally with the rotating shaft 41, and the fan 47 is configured as a centrifugal fan. Furthermore, an exhaust hole 31A is formed in the housing 20 radially outside the fan 47. This allows the airflow AR1 generated by the fan 47 to cause air to flow into the motor housing 24 from the intake hole 26D, and the air that has flowed into the motor housing 24 to be exhausted from the exhaust hole 31A. Therefore, the motor 40 can be cooled by the airflow AR1.

The housing 20 is also configured to include a motor housing 24 for accommodating the motor 40, and a handle housing 22 having a pair of cover members 23 that sandwich the motor housing 24 from the left and right. A bearing retaining portion 26 is formed in the motor housing 24, and an exposure hole 22B is formed in the handle housing 22 to expose the bearing retaining portion 26. This allows the motor 40 to be assembled to the motor housing 24 as a unit, and the motor housing 24 to be connected to the handle housing 22. This improves the ease of assembly of the impact drill 10.

In the present embodiment, the bearing accommodating portion 26C and the air inlet passage 26E are connected by the communication groove 26F in the bearing holder 26, but the configuration for connecting the bearing accommodating portion 26C and the air inlet passage 26E is not limited to this. For example, a hole may be formed in the bearing holder 26, and the bearing accommodating portion 26C and the air inlet passage 26E may be connected by the hole.

In addition, in this embodiment, the bottom of the communicating groove 26F of the bearing retaining portion 26 is positioned at the middle part of the side wall 26B in the fore-and-aft direction, but the bottom of the communicating groove 26F of the bearing retaining portion 26 may be extended to the bottom wall 26A of the bearing retaining portion 26 to increase the groove depth of the communicating groove 26F.

In addition, in this embodiment, a communicating groove 26F is formed radially inward of the first air intake hole 26D1 in the air intake hole 26D, but a communicating groove 26F may also be formed radially inward of the first air intake hole 26D1 and the second air intake hole 26D2.

In addition, in this embodiment, the dust seal 80 is arranged to rotate integrally with the rotating shaft 41 of the motor 40, but the dust seal 80 may also be configured to be fixed to the motor housing 24.

In addition, in this embodiment, the dust seal 80 is formed with a wing portion 80A, but the wing portion 80A may be omitted from the dust seal 80.

10...Vibration drill (power tool), 20...Housing, 22...Handle housing, 22B...Exposure hole, 23...Cover member, 24...Motor housing, 26...Bearing holder, 26B...Side wall, 26D...Intake hole (communication hole), 26F...Communication groove (exposure portion, groove portion), 31A...Exhaust hole, 40...Motor, 41...Rotating shaft, 45...Rear motor bearing, 47...Fan, 50...Drive mechanism, 70...Battery pack, 80...Dust seal (sealing member), 80A...Blade portion, T...Tip tool

Claims (13)

A housing that accommodates a motor;
a bearing that rotatably supports a rotating shaft of the motor or a drive shaft that is driven by the rotation of the motor;
a communication hole formed on the radially outer side of the bearing of the housing, the communication hole communicating between the inside and the outside of the housing;
a bearing holder provided in the housing and formed in a bottomed cylindrical shape to accommodate the bearing therein;
Equipped with
The bearing retaining portion has a side wall that retains the outer peripheral surface of the bearing, and the side wall has an exposed portion that exposes only the front portion of the outer peripheral surface of the bearing radially outward to the air path of the air flowing through the communication hole . A housing that accommodates a motor;
a bearing that rotatably supports a rotating shaft of the motor or a drive shaft that is driven by the rotation of the motor;
a communication hole formed on the housing radially outward of the bearing, the communication hole communicating between the inside and the outside of the housing;
a bearing holder provided in the housing and formed in a bottomed cylindrical shape to accommodate the bearing therein;
Equipped with
The bearing retaining portion has a side wall that retains the outer peripheral surface of the bearing, and the side wall has an exposed portion that exposes only a front circumferential portion of the outer peripheral surface of the bearing to the air path of the air flowing through the communication hole. A housing that accommodates a motor;
a bearing that rotatably supports a rotating shaft of the motor or a drive shaft that is driven by the rotation of the motor;
a communication hole formed on the housing radially outward of the bearing, the communication hole communicating between the inside and the outside of the housing;
a bearing holder provided in the housing and formed in a bottomed cylindrical shape to accommodate the bearing therein;
Equipped with
the bearing holder has a side wall that holds an outer circumferential surface of the bearing, and an exposure portion that exposes a part of the bearing to an air passage for air flowing through the communication hole is formed on the side wall;
A power tool in which the communicating holes are arranged in a row in the circumferential direction of the bearing holding portion, and the exposed portions are formed radially inward of every other communicating hole in the circumferential direction of the bearing holding portion. The power tool according to any one of claims 1 to 3, wherein the communication hole is formed in the bearing holding portion. The power tool according to any one of claims 1 to 3, wherein the exposed portion is configured so that only a portion of a front portion of the outer circumferential surface of the bearing is exposed to the air passage side. the exposed portion is configured as a groove portion that communicates with the communication hole and the inside of the bearing holder and that extends in the axial direction of the bearing holder,
A plurality of the communication holes are arranged in a line in a circumferential direction of the bearing holder,
The power tool according to any one of claims 1 to 3, wherein a plurality of the grooves are formed radially inwardly of every other one of the communication holes in the circumferential direction of the bearing holder. 4. The power tool according to claim 1, wherein the bearing is covered by the housing from one axial side and is covered by a seal member from the other axial side. 8. A power tool according to claim 7, wherein the seal member is fixed to the rotary shaft so as to be rotatable integrally therewith. The seal member is formed with a wing portion,
The power tool according to claim 8 , wherein the blade portion generates an air flow directed radially outwardly of the rotating shaft. A fan is provided on the other axial side of the rotating shaft,
The power tool according to any one of claims 1 to 3, wherein the housing is formed with an exhaust hole for discharging the airflow generated by the fan. The housing includes:
a motor housing that houses the motor;
a handle housing having a pair of cover members that sandwich the motor housing;
The power tool according to any one of claims 1 to 3, comprising: The housing accommodates a drive mechanism that transmits a driving force of the motor to a tool bit ,
The power tool according to any one of claims 1 to 3, wherein the drive mechanism is configured to be switchable between a first mode in which a rotational force is applied to the tool tip and a second mode in which a rotational force and an impact force are applied to the tool tip. The power tool according to any one of claims 1 to 3, wherein the motor is driven by a battery pack that is detachable from the housing.

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