阅读说明：本技术 齿轮结构体、和具有齿轮结构体的马达组装体以及动力工具 (Gear structure, and motor assembly and power tool having the same ) 是由 横山聪哉 于 2019-01-24 设计创作，主要内容包括：本发明提供使润滑剂更长期地维持在锥齿轮上的齿轮结构体。齿轮结构体(14)具备齿轮箱(42)、以及第一锥齿轮(44)及第二锥齿轮(46)。齿轮箱(42)具有与第二锥齿轮(46)的齿(54)对置且呈环状延伸的齿轮对置面(56)。齿轮对置面(56)具有：润滑剂接受部(60),其相对于第一锥齿轮(44)位于第二锥齿轮(46)的旋转方向上的前方侧；润滑剂涂敷部(62),其相对于润滑剂接受部(60)位于旋转方向上的前方侧,且比润滑剂接受部(60)接近该第二锥齿轮(46)；以及引导部(64),其从润滑剂接受部(60)朝向润滑剂涂敷部(62)倾斜。从第一锥齿轮(44)飞散的润滑剂被润滑剂接受部(60)阻挡而一边被引导部(64)引导一边流动至润滑剂涂敷部(62),且在润滑剂涂敷部(62)被涂敷于第二锥齿轮(46)。(The invention provides a gear structure which can maintain lubricant on a bevel gear for a longer period. The gear structure (14) is provided with a gear box (42), and a first bevel gear (44) and a second bevel gear (46). The gear case (42) has a gear facing surface (56) that faces the teeth (54) of the second bevel gear (46) and extends annularly. The gear facing surface (56) has: a lubricant receiving portion (60) located on the front side in the rotation direction of the second bevel gear (46) with respect to the first bevel gear (44); a lubricant applying section (62) which is located on the front side in the rotation direction with respect to the lubricant receiving section (60) and which is closer to the second bevel gear (46) than the lubricant receiving section (60); and a guide section (64) that is inclined from the lubricant receiving section (60) toward the lubricant applying section (62). The lubricant scattered from the first bevel gear (44) flows to the lubricant application section (62) while being blocked by the lubricant receiving section (60) and being guided by the guide section (64), and is applied to the second bevel gear (46) at the lubricant application section (62).)

1. A gear structure, wherein,

the gear structure is provided with:

a gear case;

a first bevel gear rotatably disposed about a first rotation axis within the gear case; and

a second bevel gear rotatably disposed in the gear case about a second rotation axis intersecting the first rotation axis and meshing with the first bevel gear,

the gear case has a gear opposing surface that opposes the teeth of the second bevel gear in the direction of the second rotation axis and extends annularly,

the gear facing surface has: a lubricant receiving portion that is located on a front side in a rotation direction of the second bevel gear with respect to the first bevel gear and blocks lubricant that is scattered from the first bevel gear; a lubricant applying portion that is located on a front side in the rotation direction with respect to the lubricant receiving portion and is closer to the second bevel gear than the lubricant receiving portion; and a guide portion that extends from the lubricant receiving portion to the lubricant applying portion and guides the lubricant blocked by the lubricant receiving portion to the lubricant applying portion.

2. The gear structure according to claim 1,

at least the guide portion is inclined so as to approach the second bevel gear from the lubricant receiving portion toward the lubricant applying portion in the rotation direction.

3. The gear structure according to claim 1 or 2,

the lubricant applying portion is inclined so as to approach the second bevel gear toward a radially outer side of the second bevel gear.

4. The gear structure according to any one of claims 1 to 3,

the gear facing surface has a gear receiving recess portion that covers a part of the first bevel gear from the opposite side of the second bevel gear, and the lubricant receiving portion is formed so as to be connected to the gear receiving recess portion.

5. The gear structure according to claim 4,

the gear housing recess portion extends to a position closer to the second bevel gear than the lubricant receiving portion is on a rear side in the rotational direction with respect to the first bevel gear.

6. The gear structure according to any one of claims 1 to 5,

the gear case has an inner peripheral surface that extends in an annular shape in proximity to the outer peripheral surface of the second bevel gear and blocks the lubricant scattered from the second bevel gear, the gear opposing surface extends in an annular shape along the inner peripheral surface,

the gear facing surface further includes: an auxiliary lubricant applying portion that approaches the second bevel gear at a position midway from the lubricant applying portion to the first bevel gear in the rotation direction of the second bevel gear; and an auxiliary guide portion that is inclined so as to approach the second bevel gear toward the auxiliary lubricant applying portion in the rotation direction, and that guides the lubricant that is caught by the inner peripheral surface to the auxiliary lubricant applying portion.

7. A gear structure, wherein,

the gear structure is provided with:

a gear case;

a first bevel gear rotatably disposed about a first rotation axis within the gear case; and

a second bevel gear rotatably disposed in the gear case about a second rotation axis intersecting the first rotation axis and meshing with the first bevel gear,

the gear box has: an inner peripheral surface that extends in an annular shape in proximity to the outer peripheral surface of the second bevel gear and blocks the lubricant that flies off from the second bevel gear; and a gear opposing surface that opposes the teeth of the second bevel gear in the direction of the second rotation axis and extends annularly along the inner peripheral surface,

the gear facing surface has: a lubricant application section that is close to the teeth of the second bevel gear; and a guide portion that is inclined so as to approach the second bevel gear toward the lubricant application portion in a rotation direction of the second bevel gear, and that guides the lubricant that is caught by the inner peripheral surface to the lubricant application portion.

8. A motor assembly, wherein,

the motor assembly includes:

a motor having a rotating shaft;

a gear structure according to any one of claims 1 to 7, wherein the first bevel gear is coupled to the rotating shaft and driven to rotate; and

an output shaft to which the second bevel gear is fixed and which extends along the second rotation axis to an outside of the gear case.

9. A power tool in which, in a power tool,

the power tool includes the motor assembly according to claim 8, and is driven by using the motor as a power source.

Technical Field

The present invention relates to a gear structure provided with a bevel gear, a motor assembly provided with the gear structure, and a power tool provided with the motor assembly.

Background

For example, a power tool such as a piercing machine using an electric motor as a power source includes a gear structure body including a plurality of gears for transmitting a rotation output of the electric motor while reducing the speed. The gear structure has various forms, and one of them is a gear structure provided with a bevel gear.

The gear structure provided with the bevel gears includes a first bevel gear coupled to an output shaft of the motor and driven to rotate, and a second bevel gear coupled to an output side of the power tool and driven to rotate, and the first bevel gear and the second bevel gear are disposed in the gear box such that respective rotation axes thereof are substantially orthogonal to each other. In a gear structure having such bevel gears, two bevel gears may be arranged in a direction substantially perpendicular to each other, and a space in a gear box in which the bevel gears are arranged may be large (patent document 1). In order to reduce the frictional resistance between the bevel gears, the bevel gears in the gear box are coated with a lubricant such as grease.

Disclosure of Invention

Problems to be solved by the invention

The lubricant applied to the bevel gear in the gear box is gradually scattered by the centrifugal force of the rotating bevel gear, but the scattered lubricant adheres to the inner surface of the gear box and stays in this position without flowing as it is. As a result, the amount of lubricant adhering to the teeth of the bevel gears gradually decreases, the lubricity between the bevel gears decreases, and the frictional resistance increases. As a result, the teeth of the bevel gears may be worn away, and the power transmission efficiency between the bevel gears may be reduced.

In view of the problems of the prior art described above, an object of the present invention is to provide a gear structure in which a lubricant once scattered from a bevel gear is applied again to the bevel gear to maintain the lubricant on the bevel gear for a longer period of time, a motor assembly including the gear structure, and a power tool including the motor assembly.

Means for solving the problems

That is, the present invention provides a gear structure in which,

the gear structure includes:

a gear case;

a first bevel gear rotatably disposed around a first rotation axis in the gear case; and

a second bevel gear rotatably disposed in the gear case about a second rotation axis intersecting the first rotation axis and meshing with the first bevel gear,

the gear case has a gear opposing surface that extends annularly while opposing the teeth of the second bevel gear in the direction of the second rotation axis,

the gear facing surface has: a lubricant receiving portion that is located on a front side in a rotation direction of the second bevel gear with respect to the first bevel gear and blocks lubricant that is scattered from the first bevel gear; a lubricant applying portion located on a front side in the rotation direction with respect to the lubricant receiving portion and closer to the second bevel gear than the lubricant receiving portion; and a guide portion that extends from the lubricant receiving portion to the lubricant applying portion and guides the lubricant blocked by the lubricant receiving portion to the lubricant applying portion.

When the first bevel gear rotates, the lubricant adhering to the teeth of the first bevel gear gradually scatters due to centrifugal force. Particularly, on the front side in the rotation direction of the second bevel gear, the lubricant scatters from the first bevel gear toward the gear opposing surface of the gear box. In this gear structure, the lubricant receiving portion of the gear facing surface blocks at least a part of the lubricant that is scattered from the first bevel gear. The lubricant is continuously scattered from the first bevel gear, and the lubricant received by the lubricant receiving portion is pressed by the lubricant scattered later and gradually flows in the rotation direction, and reaches the lubricant applying portion while being guided by the guide portion. Since the lubricant applying portion is close to the second bevel gear, the lubricant reaching the lubricant applying portion comes into contact with the second bevel gear to be applied to the second bevel gear. The lubricant applied to the second bevel gear is also applied to the first bevel gear when the second bevel gear meshes with the first bevel gear. In this gear structure, the lubricant that once scatters from the first bevel gear passes through the guide portion from the lubricant receiving portion to reach the lubricant applying portion, and is applied to the second bevel gear and the first bevel gear. Therefore, the lubricant can be continuously maintained in the bevel gear for a longer period of time than in the conventional gear structure.

Preferably, at least the guide portion of the gear facing surface may be inclined so as to approach the second bevel gear from the lubricant receiving portion toward the lubricant applying portion in the rotation direction.

The guide portion is inclined, so that the lubricant receiving portion can be more smoothly guided to the lubricant applying portion.

Further, the lubricant applying portion may be inclined so as to approach the second bevel gear toward the radially outer side of the second bevel gear.

Specifically, the gear facing surface may have a gear housing recess portion that covers a part of the first bevel gear from the opposite side of the second bevel gear, and the lubricant receiving portion may be formed so as to be connected to the gear housing recess portion.

In this case, the gear housing recess may extend to a position closer to the second bevel gear than the lubricant receiver on a rear side in the rotation direction of the first bevel gear.

It may be preferable that,

the gear box has an inner peripheral surface which is close to the outer peripheral surface of the second bevel gear and extends annularly and blocks the lubricant flying from the second bevel gear,

the gear opposite surface extends along the inner circumferential surface in a ring shape,

the gear opposite surface is also provided with; an auxiliary lubricant applying portion that is located near the second bevel gear at a position midway from the lubricant applying portion to the first bevel gear in the rotation direction of the second bevel gear; and an auxiliary guide portion that is inclined so as to approach the second bevel gear toward the auxiliary lubricant applying portion in the rotation direction, and that guides the lubricant that is caught by the inner peripheral surface to the auxiliary lubricant applying portion.

With this configuration, the lubricant that is scattered from the second bevel gear and blocked by the inner peripheral surface of the gear case is guided by the auxiliary guide portion to reach the auxiliary lubricant applying portion, and is applied to the second bevel gear again. This can maintain the lubricant on the bevel gear for a longer period of time.

Further, the present invention provides a gear structure, wherein,

the gear structure includes:

a gear case;

a first bevel gear rotatably disposed around a first rotation axis in the gear case; and

a second bevel gear rotatably disposed in the gear case about a second rotation axis intersecting the first rotation axis and meshing with the first bevel gear,

the gear box is provided with: an inner peripheral surface which extends in an annular shape in proximity to the outer peripheral surface of the second bevel gear and blocks the lubricant scattered from the second bevel gear; and a gear opposing surface that opposes the teeth of the second bevel gear in the direction of the second rotation axis and extends annularly along the inner peripheral surface,

the gear facing surface has: a lubricant application section that is adjacent to a tooth of the second bevel gear; and a guide portion that is inclined so as to approach the second bevel gear toward the lubricant application portion in a rotation direction of the second bevel gear, and guides the lubricant that is blocked by the inner peripheral surface to the lubricant application portion.

In this gear structure, the lubricant that has splashed from the rotating second bevel gear is blocked by the inner peripheral surface of the gear case, and is pressed by the continuously splashed lubricant to gradually flow along the rotation direction of the second bevel gear, and reaches the lubricant applying portion while being guided by the inclined guide portion. Since the lubricant applying portion is close to the second bevel gear, the lubricant reaching the lubricant applying portion comes into contact with the second bevel gear to be applied to the second bevel gear. In this gear structure, the lubricant that has once scattered from the second bevel gear is guided to the lubricant applying portion by the inclined guide portion and applied to the second bevel gear again. Therefore, the lubricant can be continuously maintained in the bevel gear for a longer period of time than in the conventional gear structure.

The present invention also provides a motor assembly, wherein,

the motor assembly comprises:

a motor having a rotating shaft;

a gear structure that is the above-described gear structure, and the first bevel gear is coupled to the rotating shaft and driven to rotate; and

and the output shaft is fixed with the second bevel gear and extends to the outside of the gear box along the second rotation axis.

The present invention also provides a power tool including the motor assembly described above, and driven using the motor as a power source.

Hereinafter, embodiments of the power tool of the present invention will be described with reference to the drawings.

Drawings

Fig. 1 is a side view of a power tool according to an embodiment of the present invention.

Fig. 2 is a rear view of the power tool of fig. 1.

Fig. 3 is a side view of the power tool of fig. 1 with the brush cover and the main body side cover removed.

Fig. 4 is a side view of a motor assembly provided in the power tool of fig. 1.

Fig. 5 is a side sectional view of the motor assembly of fig. 4.

Fig. 6 is a sectional view taken along line a-a of fig. 5.

Fig. 7 is a side view of the motor assembly of fig. 4 in a state where a lower case of the gear structure is removed.

Fig. 8 is a rear view of the gear structure of fig. 7.

Fig. 9 is a perspective view of an upper case of the gear structure of fig. 7.

Detailed Description

As shown in fig. 1 and 2, a power tool 1 according to an embodiment of the present invention is a piercing machine including an annular cutter 2. The power tool 1 has a main body side cover 3, and as shown in fig. 3, when the main body side cover 3 is removed, the built-in motor assembly 10 is exposed. As shown in fig. 4 and 5, the motor assembly 10 includes an electric motor 12 and a gear structure 14 fixed to a front side (left side in the drawing) of the electric motor 12. The power tool 1 performs a punching operation by rotating the annular cutter 2 using the electric motor 12 of the motor assembly 10 as a power source.

As shown in fig. 5, more specifically, the electric motor 12 of the motor assembly 10 includes a motor case 16, a rotor 18 rotatably held in the motor case 16, and a stator 20 arranged around the rotor 18. A commutator 24 (fig. 4) is provided at the rear end 22 of the rotor 18, and brushes 26 are arranged around the commutator 24. In use, the brush 26 is covered and hidden by the brush cover 28 (fig. 1), but the brush 26 is exposed to the outside by removing the brush cover 28. In a state where the motor assembly 10 is incorporated in the power tool 1, the brush cover 28 can be removed without removing the main body side cover 3, and replacement of the brush 26 can be performed by removing only the brush cover 28. The rotor 18 is formed as an integral member with a rotary shaft 30 extending to the outside of the motor case 16. The blades 32 are attached to the rotary shaft 30, and the blades 32 rotate together when the rotary shaft 30 rotates. By the rotation of the blades 32, external air is taken into the motor case 16 to cool the brushes 26 and the commutator 24. Specifically, as shown in fig. 2, a body inlet 34 is formed in the rear end surface 1a of the power tool 1, and when the blade 32 rotates, air around the power tool 1 passes through the body inlet 34 (fig. 2) formed in the rear end surface 1a of the power tool 1 and is further sucked into the motor case 16 through a case inlet 36 formed in the rear of the motor case 16. Also, a cover inlet 38 (fig. 1) is formed in the brush cover 28, and air is also sucked into the motor case 16 through the cover inlet 38. The air drawn into the motor case 16 through the case inlet 36 and the cover inlet 38 mainly passes through the brush 26 and the commutator 24 and cools the brush 26 and the commutator 24. The air having passed through the brushes 26 and the commutator 24 further passes between the motor case 16 and the rotor 18, reaches the blades 32, is discharged to the outside of the motor case 16 through a case exhaust port 40 (fig. 4) of the motor case 16, and is finally discharged to the outside of the power tool 1 through a body exhaust port 41 (fig. 1) of the body side cover 3.

As shown in fig. 5, the gear structure 14 of the motor assembly 10 includes a gear case 42, a first bevel gear 44 and a second bevel gear 46 disposed in the gear case 42 so as to mesh with each other, and an output shaft 48 extending to the outside of the gear case 42. The gear case 42 includes a lower case 42-1 fixed to the motor case 16, and an upper case 42-2 mounted to the lower case 42-1. The first bevel gear 44 is fixed to the rotating shaft 30 of the electric motor 12, and the first bevel gear 44 rotates about the first rotation axis C1 in accordance with the rotation of the rotor 18 of the electric motor 12. The output shaft 48 is held by two bearings 50, 50 to be rotatable about a second rotation axis C2 orthogonal to the first rotation axis C1. The second bevel gear 46 is fixed to the output shaft 48 so as to be rotatable together with the output shaft 48 about a second rotation axis C2. In this embodiment, the electric motor 12 rotates clockwise when viewed from the rear side (right side when viewed in the drawing). Therefore, the first bevel gear 44 also rotates clockwise when viewed from the rear side, and the second bevel gear 46 and the output shaft 48 that mesh with the first bevel gear 44 rotate clockwise when viewed from above. The second bevel gear 46 is a gear having a larger diameter than the first bevel gear 44 in number of teeth, and therefore the second bevel gear 46 rotates at a lower speed than the first bevel gear 44. The output shaft 48 is drivingly coupled to the annular cutter 2 via a gear mechanism, not shown, built into the power tool 1.

As shown in fig. 6, the gear case 42 has: an inner peripheral surface 52 extending annularly in proximity to the outer peripheral surface 46a of the second bevel gear 46; and a gear opposing surface 56 that opposes the teeth 54 of the second bevel gear 46 in the direction of the second rotation axis C2 and extends annularly along the inner peripheral surface 52. As shown in fig. 7 to 9, the gear opposing surface 56 has a gear housing recess 58 that covers a part of the first bevel gear 44 from the opposite side of the second bevel gear 46. The gear housing recess 58 extends to a position closer to the second bevel gear 46 on the rear side in the rotational direction of the second bevel gear 46 (on the right side in fig. 8) than on the front side in the rotational direction of the second bevel gear 46 (on the left side in fig. 8). The gear opposing surface 56 further has a lubricant receiving portion 60, and the lubricant receiving portion 60 is located on the front side in the rotational direction of the second bevel gear 46 with respect to the first bevel gear 44. The lubricant receiver 60 is formed to be connected to the gear housing recess 58. The gear opposing surface 56 also has: a lubricant applying portion 62 that is closer to the second bevel gear 46 than the lubricant receiving portion 60 is to the front side of the lubricant receiving portion 60 in the rotation direction; and a guide portion 64 extending from the lubricant receiving portion 60 to the lubricant applying portion 62. The lubricant receiving portion 60 and the guide portion 64 substantially form one continuous curved surface, and the entire portion is inclined while being curved so as to approach the second bevel gear 46 toward the lubricant applying portion 62. The lubricant receiving portion 60 and the guide portion 64 are also inclined so as to approach the second bevel gear 46 toward the radially outer side of the second bevel gear 46. The lubricant applying portion 62 is inclined straight so as to approach the second bevel gear 46 toward the radially outer side of the second bevel gear 46. The teeth 54 of the second bevel gear 46 are inclined downward as viewed in the drawing toward the radially outer side, but the inclination of the lubricant application portion 62 is steeper than the inclination of the teeth 54 of the second bevel gear 46. As shown in fig. 7 and 9, a step portion 66, an auxiliary guide portion 68, and an auxiliary lubricant applying portion 70 are further formed on the gear opposing surface 56 next to the lubricant applying portion 62 in the rotation direction of the second bevel gear 46. The auxiliary lubricant applying portion 70 is formed so as to be close to the second bevel gear 46 at a position from the lubricant applying portion 62 to a halfway position of the first bevel gear 44 in the rotation direction of the second bevel gear 46, similarly to the lubricant applying portion 62. Similarly to the guide portion 64, the auxiliary guide portion 68 is inclined while being curved so as to approach the second bevel gear 46 toward the auxiliary lubricant applying portion 70. Two identical auxiliary guide portions 68 and auxiliary lubricant application portions 70 are continuously formed to the gear housing recess 58.

Grease is applied to the first bevel gear 44 and the second bevel gear 46 as a lubricant for reducing frictional resistance at the time of rotation.

When the electric motor 12 rotates, the first bevel gear 44 fixed to the rotating shaft 30 of the electric motor 12 rotates, and the second bevel gear 46 and the output shaft 48 also rotate in association therewith. The second bevel gear 46 has a larger number of teeth than the first bevel gear 44, and thus the second bevel gear 46 rotates at a slower speed than the first bevel gear 44. The centrifugal force is proportional to the radius of rotation and the square of the angular velocity, but in intermeshing gears, generally more centrifugal force acts on the surface of the smaller gear. In the gear structure 14, the first bevel gear 44 is smaller, and therefore a larger centrifugal force acts on the first bevel gear 44 than on the second bevel gear 46. Therefore, the grease is more scattered from the rotating first bevel gear 44. In particular, in the portion where the first bevel gear 44 gradually separates from the second bevel gear 46, the grease adhering to the second bevel gear 46 also splashes, and therefore, more grease is scattered from the first bevel gear on the forward side in the rotation direction of the second bevel gear 46.

The grease scattered from the first bevel gear 44 to the front side in the rotation direction of the second bevel gear 46 is mainly scattered in the left-upper direction as viewed in fig. 8, and is blocked by the lubricant receiving portion 60. Since the grease continuously scatters from the first bevel gear 44, the grease received by the lubricant receiving portion 60 is gradually pushed forward in the rotation direction by the grease that subsequently scatters, and flows along the guide portion 64. The grease gradually approaches the teeth 54 of the second bevel gear 46 along the guide portion 64, and when the grease reaches the lubricant applying portion 62 that approaches the second bevel gear 46, the grease comes into contact with the second bevel gear 46 and is applied to the second bevel gear 46. Further, the lubricant applying portion 62 is inclined so as to be closer to the second bevel gear 46 on the radially outer side as described above, and grease is applied to the second bevel gear 46 at the position where the teeth 54 are formed near the outer periphery of the second bevel gear 46, whereby more lubricant is applied to the teeth 54 of the second bevel gear 46. Thus, the grease scattered from the first bevel gear 44 is guided from the lubricant receiving portion 60 to the lubricant applying portion 62 by the guide portion 64 and applied to the second bevel gear 46, and the grease is applied to the first bevel gear 44 as the second bevel gear 46 meshes with the first bevel gear 44. This allows the lubricant to circulate, and the grease can be continuously maintained on the first bevel gear 44 and the second bevel gear 46 for a longer period of time. The lubricant is maintained, so that it is possible to prevent wear of the first bevel gear 44 and the second bevel gear 46 and maintain the power transmission efficiency.

The grease attached to the second bevel gear 46 is subjected to centrifugal force generated by the rotation of the second bevel gear 46, and gradually scatters toward the inner peripheral surface 52 of the gear box 42. The grease retained by the inner peripheral surface 52 is pressed by the grease splashed from the second bevel gear 46, and is gradually pressed in the rotation direction of the second bevel gear 46 to flow. The flowing grease is guided by the inclined guide portion 64 and the auxiliary guide portion 68 to approach the second bevel gear 46, and when the grease reaches the lubricant applying portion 62 and the auxiliary lubricant applying portion 70, the grease is applied to the second bevel gear 46 in contact with the second bevel gear 46. In the gear structure 14, the grease scattered from the second bevel gear 46 to the inner peripheral surface 52 of the gear case 42 is applied to the second bevel gear 46 again, and the grease circulates.

The gear facing surface 56 and the inner peripheral surface 52 of the gear case 42 may be subjected to a water-repellent and oil-repellent surface treatment to facilitate the flow of the grease.

Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment. For example, the power tool is not limited to a fixed-type boring machine, and may be another power tool such as a hand-held screwdriver. Further, the motor assembly may include an air motor instead of the electric motor. The guide portion may be inclined linearly or may have another shape such as a stepped shape. The number of the auxiliary guide portions and the auxiliary lubricant applying portions may be arbitrarily changed. Further, the lubricant receiving portion, the guide portion, and the lubricant applying portion may be provided only without the auxiliary guide portion and the auxiliary lubricant applying portion, or at least one auxiliary guide portion and at least one auxiliary lubricant applying portion may be provided only. The first rotation axis of the first bevel gear and the second rotation axis of the second bevel gear do not necessarily intersect at right angles, and may intersect at other angles. In the above-described gear structure, the first bevel gear is held by being directly fixed to the rotating shaft of the electric motor, but may be provided with an input shaft rotatably held by the gear box, the first bevel gear is fixed to the input shaft, the input shaft is coupled to the rotating shaft of the electric motor, and the first bevel gear and the rotating shaft of the electric motor are indirectly coupled and driven to rotate.

Description of the reference numerals

1 Power tool

1a rear end face

2 annular cutter

3 main body side cover

10 Motor assembly

12 electric motor

14 Gear Structure

16 motor box

18 rotor

20 stator

22 rear end portion

24 commutator

26 electric brush

28 electric brush cover

30 rotating shaft

32 blade

34 main body suction inlet

36 box suction inlet

38 cover air suction inlet

40 boxes of air vents

41 body exhaust port

42 gearbox

42-1 lower tank

42-2 Upper tank

44 first bevel gear

46 second bevel gear

46a outer peripheral surface

48 output shaft

50 bearing

52 inner peripheral surface

54 teeth

56 opposite gear surfaces

58 gear receiving recess

60 lubricant receiving part

62 lubricant application part

64 guide part

66 step part

68 auxiliary guide part

70 auxiliary lubricant applying part

C1 first axis of rotation

C2 second axis of rotation.