EP4659909A1 - Work device - Google Patents

Abstract

A work machine suppressing reduction in cooling efficiency of a motor and a driving mechanism is provided. An electric tool 10 includes: a motor 72; a fan 82; an inner housing 42; an outer housing 22; and a limiter portion 104. The inner housing 42 is provided with an inner inflow portion 56 and an inner outflow portion 58, and includes a motor casing 44 and a head casing 62. The outer housing 22 is provided with an outer inflow portion 26 and an outer outflow portion, and supports the inner housing 42 through a rubber member. The limiter portion 104 limits airflow flowing between the inner housing 42 and the outer housing 22. The limiter portion 104 includes: a first wall 106 protruding from the outer housing 22 toward the inner housing 42; and a second wall 108 positioned between the first wall 106 and the inner inflow portion 56 in a front and back direction and protruding from the inner housing 42 toward the outer housing 22.

Description

TECHNICAL FIELD
• The present invention relates to a work machine driven by driving of a motor.
BACKGROUND ART
• A reciprocating tool of a Patent Document 1 includes a housing configuring a main body. The housing is made of a motor casing and a gear casing that are integrally formed. The gear casing houses a blade therein. The blade is reciprocated by a motor.
RELATED ART DOCUMENT PATENT DOCUMENT
• Patent Document 1: Japanese Patent Application Laid-open Publication No. 2016-87725
SUMMARY OF THE INVENTION
• In a work machine having a configuration as described in the Patent Document 1, vibration generated by the reciprocation of the tool propagates to the housing. A configuration including a vibration damper structure arranged between motor/mechanism portions that are generation sources of the vibration and a casing for housing the motor and the mechanism portion is proposed as a configuration for suppressing the propagation of the vibration to the housing. This configuration may need casings for holding components of the motor and the mechanism portion.
• Incidentally, the motor and the mechanism portion generate heat due to the driving, and therefore, need to be cooled. Therefore, a configuration for generating airflow inside the motor casing that houses the motor is proposed. On the other hand, the mechanism portion is possibly difficult to be driven when being directly cooled, and therefore, a configuration for generating airflow outside the mechanism portion casing that houses the mechanism portion is proposed.
• However, the configuration generates the airflow inside the motor casing for cooling the motor and the airflow outside the mechanism portion casing for cooling the mechanism portion, and therefore, turbulent airflow may be generated at a confluent part of these airflows or the like. The turbulent airflow may cause a risk of decrease in cooling efficiency in the motor and the mechanism portion.
• An objective of the present invention is to provide a work machine suppressing the decrease in the cooling efficiency in the motor and the mechanism portion.
MEANS FOR SOLVING THE PROBLEMS
• A work machine according to one embodiment includes: a motor; a fan generating airflow when being rotated by the motor; an inner casing provided with an inner inflow portion and an inner outflow portion, and including a motor accommodating portion for accommodating the motor and a mechanism accommodating portion for accommodating a driving mechanism driven by operation of the motor; an outer casing provided with an outer inflow portion and an outer outflow portion, and accommodating the inner casing while supporting the inner casing through an elastic portion; and a limiter portion positioned between the inner inflow portion and the inner outflow portion to limit the airflow flowing between the inner casing and the outer casing. The outer inflow portion, the inner inflow portion, the inner outflow portion and the outer outflow portion are positioned such that the air flows into the motor accommodating portion through the outer inflow portion and the inner inflow portion while the air flows out from the outer outflow portion through the inner outflow portion and a gap between the outer casing and the mechanism accommodating portion. In a direction in which the fan and the motor are arranged, in which the direction is defined as an arrangement direction, the limiter portion includes a first wall protruding from the outer casing toward the inner casing and a second wall being positioned between the first wall and the inner inflow portion in the arrangement direction and protruding from the inner casing toward the outer casing.
• A work machine according to one embodiment includes: a motor; a fan generating airflow when being rotated by the motor; an inner casing provided with an inner inflow portion and an inner outflow portion, and including a motor accommodating portion for accommodating the motor and a mechanism accommodating portion for accommodating a driving mechanism driven by operation of the motor; an outer casing provided with an outer inflow portion and an outer outflow portion, and accommodating the inner casing while supporting the inner casing through an elastic portion; and a limiter portion positioned between the inner inflow portion and the inner outflow portion to limit the airflow flowing between the inner casing and the outer casing. The outer inflow portion, the inner inflow portion, the inner outflow portion and the outer outflow portion are positioned such that the air flows into the motor accommodating portion through the outer inflow portion and the inner inflow portion while the air flows out from the outer outflow portion through the inner outflow portion and a gap between the outer casing and the mechanism accommodating portion. In a direction in which the fan and the motor are arranged, in which the direction is defined as an arrangement direction, the limiter portion includes a first wall provided in the outer casing and a second wall provided in the inner casing and facing the first wall in the arrangement direction.
EFFECTS OF THE INVENTION
• According to the present invention, the decrease in the cooling efficiency of the motor and the driving mechanism can be suppressed.
BRIEF DESCRIPTIONS OF THE DRAWINGS
• [FIG. 1] is a perspective view illustrating a work machine.
• [FIG. 2] is a cross-sectional view illustrating an inner structure of the work machine.
• [FIG. 3] is a side view illustrating an inside of the work machine in which an inner housing is exposed out.
• [FIG. 4] is an expanded view illustrating a motor casing of the inner housing.
• [FIG. 5] is a cross-sectional view illustrating a state of airflow inside the work machine, viewed from above.
• [FIG. 6] is a cross-sectional view illustrating the state of airflow inside the work machine, viewed from left.
• [FIG. 7] is an expanded view illustrating portions provided with a first wall and a second wall in the outer housing and the inner housing.
• [FIG. 8] is a cross-sectional view illustrating a part of the work machine taken along a line A-A of FIG. 3, viewed from front.
• [FIG. 9] is a graph illustrating a relation between an inflow port shift amount and an air blow amount at the outer inflow portion.
• [FIG. 10] is a graph illustrating a relation between a second wall shift amount and the air blow amount at the outer inflow portion.
• [FIG. 11] is a graph illustrating a relation between a first wall shift amount and the air blow amount at the outer inflow portion.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
• Hereinafter, one embodiment of the present invention will be described with reference to the accompanying drawings. The explanation will be made along with a direction illustrated with front and back arrows in each drawing set as a front and back direction, a direction illustrated with right and left arrows set as a right and left direction, and a direction illustrated with up and down arrows set as an up and down direction. The front and back direction, the right and left direction, and the up and down direction are perpendicular to one another.
• Note that the front and back direction is one example of an arrangement direction in which a fan 82 and a motor 72 described later are arranged as well as one example of an axial direction of the motor 72. Regarding the front and back direction, one end side at which a tip tool 14 described later is positioned is set as the front side, and the other side at which a battery pack 12 is positioned is set as the back side. The up and down direction is one example of a crossing direction crossing the arrangement direction.
[Configuration of Electric Tool]
• FIG. 1 illustrates an electric tool 10 that is one example of the work machine. The battery pack 12 and the tip tool 14 are attached to the electric tool 10.
• The battery pack 12 is attachable to and detachable from a back end of an outer housing 22 described later. The electric tool 10 is a multifunctional tool of a cordless type operated by power of the battery pack 12. The electric tool 10, for example, reciprocates (oscillates) the tip tool 14 around an axis extending in the up and down direction.
• As illustrated in FIG. 2, the electric tool 10 includes the outer housing 22, an inner housing 42, the motor 72, the fan 82, a driving mechanism 84, a limiter portion 104 and a guide portion 105 (FIG. 3). The electric tool 10 further includes a rubber member 98, an annular member 102 and a controller 96.
[Outer Housing]
• The outer housing 22 is one example of the outer casing, and forms an outer frame of the electric tool 10. The outer housing 22 is made of, for example, a resin composite. The outer housing 22 is shaped into a cylindrical shape having a center axis in the front and back direction, and extends in the front and back direction. The outer housing 22 is divided into a right housing 23 and a left housing 24 at a center in the right and left direction (FIG. 1). The outer housing 22 includes an upper wall 22A, a lower wall 22B, a front wall 22C at a front end, an outer surface 22D and an inner surface 22E.
• The outer housing 22 is provided with outer inflow portions 26 and 28 (FIG. 1) and an outer outflow portion 32. The outer housing 22 encloses an inner housing 42 described later, and supports the inner housing 42 (head casing 62) through the rubber member 98.
(Outer Inflow Portion)
• As illustrated in FIGs. 3 and 5, the outer inflow portion 26 is arranged at a center of the right housing 23 in the front and back direction as well as a center thereof in the up and down direction. The outer inflow portion 26 is at a right back side of the motor 72. The outer inflow portion 26 includes a plurality of inflow ports 26A. The plurality of inflow ports 26A are arranged in the up and down direction. Each of the plurality of inflow ports 26A is a long hole penetrating the right housing 23 in the right and left direction and extending in an oblique direction crossing the front and back direction.
• As illustrated in FIG. 5, the outer inflow portion 28 is arranged at a center of the left housing 24 in the front and back direction as well as a center thereof in the up and down direction. The outer inflow portion 28 is at a left back side of the motor 72. The outer inflow portion 28 includes a plurality of inflow ports 28A. The plurality of inflow ports 28A are arranged in the up and down direction. Each of the plurality of inflow ports 28A is a long hole penetrating the left housing 24 in the right and left direction and extending in an oblique direction crossing the front and back direction. The outer inflow portion 26 and the outer inflow portion 28 are almost symmetric to each other across the center of the outer housing 22 in the right and left direction.
(Outer Outflow Portion)
• As illustrated in FIG. 6, the outer outflow portion 32 includes, for example, a first outflow portion 34 enabling outflow from a first space S1 described later and a second outflow portion 36 enabling outflow from a second space S1 described later. The outer outflow portion 32 is closer to the driving mechanism 84 (front side) than an eccentric shaft 86 and an annular member 102 (FIG. 2) described later. At least a part of the outer outflow portion 32 is closer to the front side than an output shaft 90.
[First Outflow Portion]
• The first outflow portion 34 is arranged at a part of the upper wall 22A of the outer housing 22, the part being at a center in the right and left direction as well as a front end. The first outflow portion 34 is formed as an opening penetrating the upper wall 22A in the up and down direction. The first outflow portion 34 is shaped into a rectangular shape having a dimension in the front and back direction longer than a dimension in the right and left direction. The first outflow portion 34 is closer to the front side than the fan 82. Also, the first outflow portion 34 is upper than a head casing 62 described later. Further, the first outflow portion 34 is at a position facing the head casing 62 in the up and down direction. Still further, the first outflow portion 34 is closer to the front side than the motor 72 in the front and back direction.
[Second Outflow Portion]
• The second outflow portion 36 is arranged at a part of the lower wall 22B of the outer housing 22, the part being at a center in the right and left direction as well as a front end. The second outflow portion 36 is formed as an opening penetrating the lower wall 22B in the up and down direction. The second outflow portion 36 is shaped into a circular shape when being viewed in the up and down direction. The second outflow portion 36 is lower than the head casing 62 described later, and faces a part of a unit casing 88 in a radial direction. Also, the second outflow portion 36 is closer to the front side than the motor 72 in the front and back direction.
• As illustrated in FIG. 2, a clamp lever 16 is arranged inside the first outflow portion 34. The clamp lever 16 is arranged at an upper end of the head casing 62 to be rotatable around a pin 17. A push piece 21 is attached to the clamp lever 16. When the clamp lever 16 is operated in one or the other side of a rotational direction, a shaft holder 91 described later is moved upward or downward, thereby enabling the tip tool 14 to be attachable or detachable. A trigger 18 for switch between driving and stop of the motor 72 is arranged at an upper portion of the outer housing 22.
<Inner Housing>
• As illustrated in FIG. 6, the inner housing 42 is one example of the inner casing, and forms an inner frame of the electric tool 10. The inner housing 42 is made of, for example, a resin composite. The inner housing 42 extends from the center of the outer housing 22 in the front and back direction to the front end. The inner housing 42 is divided at a center in the right and left direction into a right housing and a left housing. The inner housing 42 includes the motor casing 44 and the head casing 62. Also, the inner housing 42 includes an inner inflow portion 56 and an inner outflow portion 58 described later.
(Motor Casing)
• The motor casing 44 is one example of a motor accommodating portion for accommodating the motor 72. The motor casing 44 includes, for example, a casing main body 46 and an attachment receiving portion 54. The casing main body 46 is shaped into almost a cylindrical shape having a center axis extending in the front and back direction. A front end of the casing main body 46 opens to the front side. A back end of the casing main body 46 is closed. The casing main body 46 has an inner circumferential surface 46A (FIG. 2) and an outer circumferential surface 46B.
• The attachment receiving portion 54 is fixed to the front end of the casing main body 46. The attachment receiving portion 54 is a portion attached to the head casing 62 by using a screw 47. The attachment receiving portion 54 is made of a metal (such as aluminum). The attachment receiving portion 54 supports a ball bearing 78 (bearing member) described later. Further, a heatsink 54A is provided in the attachment receiving portion 54 (FIG. 3). The heatsink 54A is provided in each of four points of the attachment receiving portion 54, in other words, four upper, lower, right and left outer surfaces thereof. The heatsink 54A has a fin shape (a plurality of concave/convex shapes), and functions to accelerate the heat release in the attachment receiving portion 54. Note that the heatsinks 54A are illustrated in only FIG. 3, while illustration of the right and lower heatsinks 54A taking the reference symbols is omitted. The motor casing 44 is provided with a vertical wall 52 (FIG. 7) described later. In other words, the inner housing 42 is provided with the vertical wall 52.
• As illustrated in FIG. 5, the motor casing 44 is provided with stator support portions 48 and 49. Each of the stator support portions 48 and 49 is an annular rib protruding inward in the radial direction from the inner circumferential surface 46A of the casing main body 46. The stator support portion 48 is closer to the front side than the stator support portion 49. The stator support portions 48 and 49 support a stator 76 described later. The motor casing 44 is distant from the outer housing 22, and is attached to the head casing 62 described later.
[Inner Inflow Portion]
• As illustrated in FIG. 4, the casing main body 46 is provided with the inner inflow portion 56. The inner inflow portion 56 includes, for example, four inflow ports 57A and four inflow ports 57B. Two of the four inflow ports 57A are arranged on each of the left and the right of the casing main body 46 to be spaced apparat from each other in the circumferential direction.
• Two of the four inflow ports 57B are arranged on each of the left and the right of the casing main body 46 to be spaced apparat from each other in the circumferential direction. The four inflow ports 57B are closer to the back side than the four inflow ports 57A. In other words, the four inflow ports 57A are components on the frontmost side of the inner inflow portion 56. Note that the left side of the casing main body 46 is illustrated in FIG. 4, and therefore, the illustration of the two inflow ports 57A and the two inflow ports 57B on the right side is omitted.
• Each of the four inflow ports 57A and the four inflow ports 57B penetrates the casing main body 46 in the radial direction. In other words, the air inflow is achieved at the inner inflow portion 56. A length of the inflow port 57A in the up and down direction is, for example, smaller than a length of the inflow port 57B in the up and down direction. A length of the inflow port 57A in the front and back direction is, for example, almost equal to a length of the inflow port 57B in the front and back direction.
[Inner Outflow Portion]
• The casing main body 46 is provided with the inner outflow portion 58. The inner outflow portion 58 includes, for example, eight outflow ports 59. Two of the outflow ports 59 are arranged on each of a left side surface, a right side surface, an upper surface and a lower surface of the casing main body 46, to be totally eight and be spaced apparat from each other in the circumferential direction. Each of the eight outflow ports 59 penetrates the casing main body 46 in the radial direction. In other words, the air outflow is achieved at the inner outflow portion 58. Note that illustration of some outflow ports 59 is omitted in FIG. 4. The eight outflow ports 59 are closer to the front side than the inner inflow portion 56 and a first wall 106 described later.
• As illustrated in FIG. 7, the inflow port 57A is between the stator support portion 48 and the inner outflow portion 58 in the front and back direction. Note that FIG. 7 illustrates one inflow port 57A and one outflow port 59.
[Vertical Wall]
• The vertical wall 52 is between the stator 76 and the fan 82 described later, and extends toward a center in the radial direction. Specifically, the vertical wall 52 is shaped into a plate shape thickened in the front and back direction. The vertical wall 52 is closer to, for example, the front side than the first wall 106 and the second wall 108 described later. The vertical wall 52 is also between the inflow port 57A and the outflow port 59 in the front and back direction. The thickness of the vertical wall 52 in the front and back direction is, for example, smaller than a thickness of the first wall 106 in the front and back direction. Note that a front-end surface of the vertical wall 52 is assumed to a front surface 52A, and a back-end surface of the vertical wall 52 is assumed to a back surface 52B. The vertical wall 52 is configured to collect a negative pressure onto a position close to the center of the fan 82, and functions as so-called fan guide (baffle plate).
(Head Casing)
• As illustrated in FIG. 3, the head casing 62 is one example of the mechanism accommodating portion for accommodating the driving mechanism 84. The head casing 62 includes a cylindrical portion 63 having a center axis extending in the up and down direction, an attachment portion 64 integrally formed with a back end of the cylindrical portion 63, and a joint portion 68 provided to a front end of the cylindrical portion 63.
• An inner space of the cylindrical portion 63 and an inner space of the attachment portion 64 are connected with an inner space of the motor casing 44. A lower end of the cylindrical portion 63 opens to the second outflow portion 36. A groove 65 is formed on an outer circumferential surface 63A of the cylindrical portion 63. The groove 65 is shaped into a U shape opening to the back side when being viewed from above. An edge 66 of the groove 65 is shaped into a rib shape. A front end of the edge 66 protrudes toward a back surface of the front wall 22C of the outer housing.
• The attachment portion 64 is attached (fastened) from the front side to the attachment receiving portion 54 by using a screw 47. A pin 17 is attached to the joint portion 68 in the right and left direction.
• As illustrated in FIG. 2, a ball bearing 71 is arranged inside the head casing 62. The ball bearing 71 supports the output shaft 90 described later to be rotatable around an axis extending in the up and down direction.
(Head Casing)
• As illustrated in FIG. 2, the motor 72 is enclosed in the motor casing 44. The motor 72 is a brushless motor. The motor 72 includes a rotary shaft 74, a rotor 75 integrally formed with the rotary shaft 74, and the stator 76 for rotating the rotor 75. The rotary shaft 74 extends in the front and back direction. The motor 72 is closer to the back side than the fan 82.
• A spindle 77 is attached to a front portion of the rotary shaft 74. The spindle 77 extends in the front and back direction, and rotates together with the rotary shaft 74. A center of the spindle 77 in the front and back direction is rotatably supported by the ball bearing 78. A front end of the spindle 77 is provided with the eccentric shaft 86 described later.
• A center axis of the eccentric shaft 86 is parallel to a center axis of the spindle 77, but is at a position deviating from the center axis of the spindle 77. Note that the rotary shaft 74 and the spindle 77 are one example of the shaft portion of the motor 72. The eccentric shaft 86 and the annular member 102 are one example of the transmission member for transmitting the driving force of the motor 72 to the driving mechanism 84.
• As illustrated in FIG. 7, a front end surface 76A of the stator 76 is between the inflow port 57A and the vertical wall 52 in the front and back direction. The front end surface 76A is one example of an end surface of the stator 76, the end surface being on the fan 82 side.
<Fan>
• As illustrated in FIG. 5, the fan 82 is a centrifugal fan that rotates around the rotary shaft 74 of the motor 72. The fan 82 is rotated by the motor 72, thereby forming the airflow inside the outer housing 22 and inside the inner housing 42. The airflow formed by the fan 82 flows out from the inner outflow portion 58 into the space between the outer housing 22 and the inner housing 42. Note that a direction of arrangement of the stator 76 and the fan 82 is the front and back direction. A positioning side of the fan 82 in the front and back direction is the front side, and a positioning side of the stator 76 in the front and back direction is the back side.
<Driving Mechanism>
• As illustrated in FIG. 2, the driving mechanism 84 includes, for example, a swinging arm 87, a unit casing 88, the ball bearing 71, the output shaft 90, the shaft holder 91, a coil spring 82 and a fixing screw 94.
• The driving mechanism 84 is driven by the operation of the motor 72. A lubricant such as grease is used on a part of the driving mechanism 84. In this case, when the driving mechanism 84 is directly cooled by the airflow, the lubricant may be dried. Therefore, in cooling the driving mechanism 84, it is preferable to cool the head casing 62, thereby indirectly cooling the driving mechanism 84.
• The swinging arm 87 includes a U-shaped arm portion 87A extending toward the back side. The arm portion 87A is positioned such that its arms sandwich an outer ring of the annular member 102 therebetween. A front portion of the swinging arm 87 is fixed to an outer circumferential surface of the unit casing 88. When the eccentric shaft 86 rotates, the eccentric shaft 86 is in contact with the arm portion 87A, thereby swinging the swinging arm 87. Therefore, the output shaft 90 swings in a rotary direction around its own axis.
• The unit casing 88 is shaped into a cylindrical shape having a center axis extending in the up and down direction. The ball bearing 71 is closer to the upper side than the swinging arm 87. The ball bearing 71 rotatably supports the output shaft 90. The output shaft 90 is a portion that holds and oscillates the tip tool 14.
• Most part of the shaft holder 91 is enclosed in the unit casing 88. An upper end of the shaft holder 91 protrudes to be upper than the unit casing 88. The upper end of the shaft holder 91 is in contact with a push piece 21. The coil spring 92 is arranged inside the unit casing 88, and applies an upward pressing force to the shaft holder 91. The fixing screw 94 fixes the tip tool 14 to the output shaft 90.
<Controller>
• The controller 96 is arranged inside the outer housing 22. Specifically, the controller 96 is attached to an inner surface of a back end of the outer housing 22. The controller 96 controls the operation of the motor 72. The controller 96 is closer to the back side than the motor 72. Further, the controller 96 is close to the back side and distant from the outer inflow portion 26. At least a part of the outer inflow portion 26 is between the controller 96 and the motor 72 in the front and back direction.
<Rubber Member>
• As illustrated in FIG. 3, a rubber member 98 is one example of the elastic portion, and is configured as an anti-vibration rubber. The rubber member 98 is shaped into a C shape when being viewed from above. The rubber member 98 is fitted with and adhered on the groove 65. The rubber member 98 includes a protrusion 99 that protrudes beyond the above-described edge 66 to outside including the front side. The protrusion 99 is attached to the inner surface of the outer housing 22.
• Since the rubber member 29 is provided, the propagation of the vibration from the head casing 62 to the outer housing 22 is suppressed. The inner housing 42 is movable relative to the outer housing 22 since the rubber member 29 is elastically deformable. Incidentally, if the inner housing 42 is vibrated by the operation of the motor 72, a distance between the motor casing 44 and the outer housing 22 may be larger than a distance between the head casing 62 and the outer housing 22 because of no rubber member 98.
• As illustrated in FIG. 6, a first flow path 25 on one side (upper side) in the up and down direction and a second flow path 27 on the other side (lower side) in the up and down direction are arranged between the outer housing 22 and the inner housing 42. The first flow path 25 is a path extending from the outer inflow portion 26 through upper sides of the motor casing 44 and the head casing 62 to the first outflow portion 34. The second flow path 27 is a path extending from the outer inflow portion 26 through lower sides of the motor casing 44 and the head casing 62 to the second outflow portion 36.
• By the rubber member 98, for example, a space S between the head casing 62 and the outer housing 22 is divided in the up and down direction into a first space S1 and a second space S2. The rubber member 98 is between the first flow path 25 and the second flow path 27 in the up and down direction. Note that dashed dotted lines S1 and S2 do not indicate specific regions but roughly indicate a region of the first space S1 and a region of the second space S2, respectively.
<Annular Member>
• As illustrated in FIG. 2, the annular member 102 is shaped into an annular shape functioning as a ball bearing. An inner ring of the annular member 102 is attached to an outer circumferential surface of the eccentric shaft 86. In other words, the annular member 102 is arranged on one end of the rotary shaft 74 of the motor 72 in the axis direction. The driving force is transmittable between an outer ring of the annular member 102 and the outer circumferential surface of the unit casing 88 through the swinging arm 87. The outer circumferential surface of the annular member 102 is a curved surface that protrudes outward.
<Limiter Portion>
• As illustrated in FIG. 7, the limiter portion 104 is between the inner inflow portion 56 and the inner outflow portion 58 in the front and back direction. The limiter portion 104 limits the airflow flowing between the inner housing 42 and the outer housing 22. Specifically, the limiter portion 104 limits (reduces) the airflow flowing from the front side to the back side and the airflow flowing from the back side to the front side in a space between the inner housing 42 and the outer housing 22. The limiter portion 104 includes, for example, a first wall 106 and a second wall 108.
(First Wall)
• The first wall 106 protrudes from the outer housing 22 toward the inner housing 42. Specifically, the first wall 106 protrudes from an inner surface 22E of the outer housing 22 toward the motor casing 44. The first wall 106 is shaped into a plate shape (rib shape) having a thickness T1 in the front and back direction. The thickness T1 is larger than a thickness T3 of the vertical wall 52 in the front and back direction.
• A tip portion 107 of the first wall 106 is closer to the inner housing 42 than a tip portion 109 of the second wall 108 in the up and down direction. The first wall 106 is closer to the inner inflow portion 56 than the inner outflow portion 58 in the front and back direction. The first wall 106 is integrally formed (integrally molded) with the outer housing 22.
• A front end surface of the first wall 106 is assumed as a front surface 106A, and a back end surface of the first wall 106 is assumed as a back surface 106B. A position of the front surface 106A in the front and back direction is, for example, almost the same as that of the back surface 52B.
(Second Wall)
• The second wall 108 is between the first wall 106 and the inner inflow portion 56 in the front and back direction, and protrudes from the inner housing 42 toward the outer housing 22. Specifically, the second wall 108 protrudes outward in the radial direction from an outer circumferential surface 46B of the motor casing 44 toward the outer housing 22. The second wall 108 is shaped into a plate shape (rib shape) having a thickness T2 in the front and back direction. The thickness T2 is, for example, larger than the thickness T1. The second wall 108 is integrally formed (integrally molded) with the motor casing 44.
• A position of a back end surface (close to the inflow port 57A) of the second wall 108 is made equal to a position of a front end surface (close to the second wall 108) of the inflow port 57A. Specifically, a front end surface of the second wall 108 is assumed as a front surface 108A, and a back end surface of the second wall 108 is assumed as a back surface 108B. Also, a front end surface of an inner wall surface configuring the inflow port 57A is assumed as a front wall surface M1, and a back end surface thereof is assumed as a back wall surface M2. In this case, positions of the back surface 108B and the front wall surface M1 in the front and back direction are the same as each other. Note that each of the back surface 108B and the front wall surface M1 is a plane expanding in the right and left direction and the up and down direction.
• A part of the first wall 106 and a part of the second wall 108 overlap each other when being viewed in the front and back direction. In FIG. 7, an overlap amount between the first wall 106 and the second wall 108 in the right and left direction is assumed as "L1".
• A distance between the first wall 106 and the second wall 108 in the front and back direction is assumed as a distance "d". In this case, the outer housing 22 supports the inner housing 42 through the rubber member 98 (FIG. 3). Therefore, the distance d varies (changes) between a distance at the time of the operation of the motor 72 and a distance at the time of the stoppage of the operation. For example, at the time of the stoppage of the operation of the motor 72, the distance d is equal to or smaller than 10 mm and equal to or larger than 0 mm. Further, at the time of the stoppage of the operation of the motor 72, the distance d is smaller than an opening width "W" of the inner outflow portion 58 in the front and back direction (when being viewed particularly in the up and down direction as illustrated in FIG. 7). At the time of the operation of the motor 72, the distance d is changed by the vibration of the inner housing 42. However, the distance d is preferably equal to or smaller than 10 mm. Note that a numerical value of the distance d is set based on simulation results described later.
• In the electric tool 10, a flow path "V" bent as cranking is made of the first wall 106 and the second wall 108. The flow path V functions as a labyrinth portion in which a flow path made of the outer housing 22 and the inner housing 42 is narrowed. Note that FIG. 7 illustrates the first wall 106 and the second wall 108 for the right side portion of the inner housing 42 and the right side portion of the outer housing 22. However, the flow path V is similarly formed for the left side portion, the upper end portion and the lower end portion.
• As illustrated in FIG. 8, the first wall 106 is arranged on almost the whole of the inner surface 22E of the outer housing 22 in the circumferential direction. The second wall 108 is circumferentially arranged on almost the whole of the outer circumferential surface 46B of the motor casing 44. Therefore, almost the whole circumferential region of the first wall 106 and the second wall 108 has the overlap amount L1 in the radial direction of the fan 82. Note that the different position in the circumferential direction makes the radial-directional overlap amount L1 different.
• As illustrated in FIG. 6, the outer inflow portion 26 and the inner inflow portion 56 are positioned such that the airflow flows into the motor casing 44 through the outer inflow portion 26 and the inner inflow portion 56. The inner outflow portion 58 and the outer outflow portion 32 are positioned such that the airflow flows from the inner outflow portion 58, and then, flows out from the outer outflow portion 32 through the gap between the outer housing 22 and the head casing 62.
<Guide Portion>
• As illustrated in FIGs. 3 and 6, the guide portion 105 is arranged between the inner outflow portion 58 and the outer outflow portion 32 in the front and back direction. The guide portion 105 is a wall portion (rib portion) that protrudes inward from the inner surface of the outer housing 22. Note that the guide portion 105 is mainly arranged on the upper and lower sides of the outer housing 22, but is not arranged on the right and left inner surfaces. Therefore, in FIG. 5 or the like, the guide portion 105 is not apparent. The guide portion 105 guides the direction of the forward-moving airflow to the inside. That is, the guide portion 105 can collect the forward-moving airflow to the inside. Incidentally, as described above, the attachment-receiving portion 54 is provided with the heatsink 54A. The air moved inward by the guide portion 105 easily hits the heatsink 54A, and therefore, the attachment-receiving portion 54 is efficiently cooled. Since the attachment-receiving portion 54 is cooled, the ball bearing 78 can be indirectly cooled, and besides, the annular member 102 and the arm portion 87A (swinging arm 87) can be also cooled. The guide portion 105 and the attachment-receiving portion 54 (particularly the heatsink 54A) are at the same position as each other in the front and back direction. In other words, the guide portion 105 and the attachment-receiving portion 54 (particularly the heatsink 54A) are at the positions that overlap each other when being viewed in the radial direction (the up and down direction). Therefore, the air guided by the guide portion 105 efficiently hits the attachment-receiving portion 54 (particularly the heatsink 54A).
<Study on Simulation Results>
• All of FIGs. 9, 10 and 11 illustrate the results provided by the simulation. Note that description of a drawing reference symbol for each portion and each member of the electric tool 10 is omitted.
• In FIG. 9, regarding an airflow volume at a position near the outer inflow portions 26 and 28, a graph G1 shows an airflow volume change by backward positioning shift of the inflow port 57A relative to the position of the second wall 108. Note that a dotted line K1 indicates an airflow volume that is lower by 10% from an airflow volume in a case of a shift amount of 0 mm. A dotted line K2 indicates an airflow volume that is lower by 20% from the airflow volume in the case of the shift amount of 0 mm. From the graph G1, it has been found that the closer to the second wall 108 (closer to the fan 82) the inflow port 57A is, the larger the airflow volume at the outer inflow portion is.
• In FIG. 10, regarding the airflow volume at the position near the outer inflow portions 26 and 28, a graph G2 shows an airflow volume change by backward positioning shift of the second wall 108 relative to the position of the first wall 106. Note that only the inflow port 57B is arranged while the inflow port 57A is not arranged. A dotted line K0 indicates an airflow volume at a start position (decrease by 0%). From the graph G2, it has been found that the closer to the first wall 106 (closer to the fan 82) the second wall 108 is, the larger the airflow volume at the outer inflow portion is. In this case, values of the airflow volumes in cases of the shift amounts of 2 mm and 8 mm are almost the same local minimum values as each other. Therefore, in consideration of an error, at the time of the stoppage of the operation of the motor 72, the distance between the first wall 106 and the second wall 108 in the front and back direction is preferably equal to or smaller than 10 mm.
• In FIG. 11, regarding the airflow volume at the position near the outer inflow portions 26 and 28, a graph G3 shows an airflow volume change by backward positioning shift of the first wall 106 relative to the position of the inner outflow portion 58. Note that the second wall 108 is not arranged. Also, only the inflow port 57B is arranged while the inflow port 57A is not arranged. A dotted line K3 indicates an airflow volume that is lower by 30% from an airflow volume in the case of the shift amount of 0 mm.
• From the graph G3, it has been found that the resultant airflow volume is maximized when the shift amount of the first wall 106 is about 0.5 mm. In other words, it has been found that the airflow volume is lowered, whether the first wall 106 is too close to or too far from the inner outflow portion 58. As seen from above, the position of the first wall 106 relative to the position of the inner outflow portion 58 is to be set as a suitable position.
<Comparative Example>
• An electric tool of a comparative example in comparison to the electric tool 10 of the present embodiment will be explained. A configuration of the electric tool of the comparative example is different from that of the electric tool 10 in that the configuration does not include the limiter portion 104. Note that illustration of the electric tool of the comparative example is omitted.
• Since the electric tool of the comparative example does not include the limiter portion 104, a part of the airflow flowing out from the inner outflow portion 58 to the gap between the outer housing 22 and the inner housing 42 may flow (flow back) to the outer inflow portion 26. Also, the airflow flowing from the outer inflow portion 26 through the outside of the motor casing 44 to the outer outflow portion 32 may disrupt the airflow flowing out from the inner outflow portion 58. Therefore, in the electric tool of the comparative example, the volume of the airflow flowing to the outer outflow portion 32 is lowered, and the head casing 62 is difficult to be cooled. In other words, in the electric tool of the comparative example, the cooling efficiency in the cooling of the driving mechanism 84 may be reduced.
[Function and Effect of Present Embodiment]
• FIG. 5 illustrates a state of the airflow flowing inside the outer housing 22 and inside the inner housing 42 provided when the motor 72 rotates the fan 82, when being viewed from above. Note that the electric tool 10 has, for example, right and left structures that are almost symmetrical to each other across the center in the right and left direction. Therefore, in FIG. 5, the airflow flowing on the right side of the electric tool 10 is illustrated with an arrow "A", and illustration of the airflow flowing on the left side thereof is omitted.
• By the rotation of the fan 82, ambient air is flown into the outer housing 22 through a plurality of inflow ports 28A of the outer inflow portion 26. This airflow is referred to as airflow "A1". A part of the airflow A1 flows into the motor casing 44 through the inflow port 57B. This airflow is referred to as airflow "A2". The airflow A2 flows forward through the gap between the rotor 75 and the stator 76.
• On the other hand, the rest of the airflow A1 flows forward through the gap between the outer housing 22 and the motor casing 44. This airflow is referred to as airflow "A3". The airflow A3 flows into the motor casing 44 through the inflow port 57A until reaching the second wall 108. The airflow A3 further flows through the gap between the vertical wall 52 and the front end surface 76A, and merges with the airflow A2. The merged airflow A2 and airflow A3 are collectively referred to as airflow "A4".
• By the rotation of the fan 82, the airflow A4 is flown out through the outflow port 59 of the inner outflow portion 58. Most of the flown-out airflow A4 flows forward through the gap between the outer housing 22 and the motor casing 44. Then, the airflow A4 flows through the gap between the outer housing 22 and the head casing 62, thereby cooling the head casing 62. The airflow A4 after cooling the head casing 62 flows out from the outer housing 22 through the outer outflow portion 32 (FIG. 2).
• On the other hand, the rest of the airflow A4 flown out through the outflow port 59 flows (flows back) through the gap between the first wall 106 and the second wall 108. This airflow is referred to as airflow "A5". The airflow A5 is difficult to flow through the labyrinth portion made of the first wall 106 and the second wall 108. Therefore, a volume of the airflow A5 is very smaller than a volume of the airflow A4. Even if the airflow A5 flows backward beyond the limiter portion 104, the airflow A5 is flown inward through the inflow port 57A again.
• FIG. 6 illustrates a state of the airflow flowing inside the outer housing 22 and inside the inner housing 42 provided when the motor 72 rotates the fan 82, when being viewed from left. Note that the airflow flowing through a portion inside as well as upper or lower side of the outer housing 22 is illustrated with an arrow "B" to be discriminated from the arrow A (FIG. 5).
• A part of the airflow A1 (FIG. 5) flown into the outer housing 22 is branched into airflow B1 flowing upward and airflow B2 flowing downward. And, the forward flow of the airflows B1 and B2 is limited by the second wall 108, and therefore, the flow goes around to the right side or the left side of the motor casing 44, and flows into the motor casing 44 through the inner inflow portion 56.
• By the rotation of the fan 82, a part of the airflow A4 (FIG. 5) is flown out through the outflow port 59 of the inner outflow portion 58. In this case, a part of the airflow A4 is flown out as the airflow B3 through the outflow port 59 on the upper surface and as the airflow B4 through the outflow port 59 on the lower surface. That is, regarding the forward-moving air flown out from the inner outflow portion 58, the airflow passing through the left side and the right side is A4, the airflow passing through the upper side is B3, and the airflow passing through the lower side is B4. The airflow A4 flown out from the outflow port 59 upper than the axis center of the rotary shaft 74 (FIG. 2) mainly passes through the first flow path 25. The airflow A4 flown out from the outflow port 59 lower than the axis center of the rotary shaft 74 (FIG. 2) mainly passes through the second flow path 27. And, the airflow B3 passes through the first flow path 25, and the airflow B4 passes through the second flow path 27. Each of the airflow referred to as A6 passing through the first flow path 25 and the airflow referred to as A7 passing through the second flow path 27 is illustrated in FIG. 6. The airflow A6 includes one airflow A4 and the airflow B3, and the airflow A7 includes another airflow A4 and the airflow B4.
• The airflow A6 passes through the first flow path 25, and cools the upper portion of the head casing 62. Then, the airflow A6 flows out from the outer housing 22 through the first outflow portion 34. The airflow A7 passes through the second flow path 27, and cools the lower portion of the head casing 62. Then, the airflow A7 flows out from the outer housing 22 through the second outflow portion 36.
• Function and effect of the electric tool 10 will be summarized below with reference to FIGs. 1 to 11. Description of each drawing reference symbol is omitted.
• In the electric tool 10, the fan 82 is rotated by the motor 72, thereby forming the airflow. This manner forms the airflow flowing from the outer inflow portion 28 through the inside of the inner housing 42 and the inner outflow portion 58 and then flowing out from the outer outflow portion 32. Further, other airflow flowing from the outer inflow portion 28 into the gap between the outer housing 22 and the inner housing 42 is formed.
• In this case, the limiter portion 104 between the inner inflow portion 56 and the inner outflow portion 58 limits the airflow flowing through the gap between the inner housing 42 and the outer housing 22. Specifically, a part of the airflow flowing from the outer inflow portion 28 is limited by the second wall 108, thereby making the airflow easy to go to the inner inflow portion 56. Further, the first wall 106 and the second wall 108 limit the backflow of a part of the airflow flown out from the inner outflow portion 58 to the inner inflow portion 56. This manner can more suppress the decrease in the volume of the airflow flowing from the inner outflow portion 58 to the outer outflow portion 32 than the above-described comparative example, and therefore, can more suppress the reduction of the cooling efficiency in the cooling of the driving mechanism 84.
• According to the electric tool 10, since the shape of the flow path between the first wall 106 and the second wall 108 is the crank shape, the air is difficult to flow through the gap between the first wall 106 and the second wall 108. This manner can further suppress the backflow of the airflow flown out from the inner outflow portion 58 to the inner inflow portion 56.
• In the electric tool 10, the inner outflow portion 58 and the first wall 106 do not face each other. This manner can prevent the guidance (the backflow) of a part of the airflow flown out from the inner outflow portion 58 to the back side after the airflow is in contact with the first wall 106.
• According to the electric tool 10, the airflow (the air backflow) flowing through the gap between the first wall 106 and the second wall 108 can be made less than that in the configuration in which the distance between the first wall 106 and the second wall 108 in the front and back direction is larger than 10 mm.
• According to the electric tool 10, the airflow (the air backflow) flowing through the gap between the first wall 106 and the second wall 108 can be made less than that in the configuration in which the distance d between the first wall 106 and the second wall 108 is larger than the opening width W of the inner outflow portion 58.
• According to the electric tool 10, at least one inflow port 57A is arranged between the stator support portion 48 and the inner outflow portion 58. Therefore, the difficulty in the downward (forward) flow of the airflow flowing in from the inner outflow portion 58 due to the contact with the stator support portion 48 can be suppressed, and therefore, the decrease in the volume of the airflow flowing out from the inner outflow portion 58 can be suppressed.
• According to the electric tool 10, the space to be secured in the inner housing 42 in the front and back direction can be made smaller than that in the configuration in which the inflow port 57A is closer to the front side than the front end surface 76A of the stator 76, and therefore, the electric tool 10 can be downsized.
• According to the electric tool 10, the airflow changed in the direction by the contact with the second wall 108 is guided as it is to the inflow port 57A, and therefore, the airflow can be efficiently taken from the inflow port 57A into the inner housing 42.
• According to the electric tool 10, the second wall 108 does not need to be manufactured as a separate member from the motor casing 44, and therefore, the number of steps for manufacturing the electric tool 10 can be decreased.
• In the electric tool 10, it is unnecessary to manufacture the first wall 106 as a separate member from the outer housing 22, and therefore, the number of steps for manufacturing the electric tool 10 can be decreased.
• According to the electric tool 10, the rubber member 98 is not arranged between the motor casing 44 and the outer housing 22 in the back portion of the inner housing 42, and therefore, the airflow easily flows through the gap between the motor casing 44 and the outer housing 22.
• In the electric tool 10, the airflow flows to the first flow path 25 on one side of the rubber member 98 and the second flow path 27 on the other side thereof. This manner prevents the cooling for only the one-side portion or the other-side portion of the rubber member 98, and therefore, the cooling efficiency of the rubber member 98 can be enhanced.
• According to the electric tool 10, the airflow in the first space S1 flows out from the first outflow portion 34, and the airflow in the second space S2 flows out from the second outflow portion 36, and therefore, the airflow in contact with the rubber member 98 can be suppressed from staying inside the outer housing 22.
• In the electric tool 10, the driving mechanism 84 is connected to one end (front end) of the rotary shaft 74 or others in the shaft direction. That is, the driving mechanism 84 is opposite in the position to the motor 72 across the annular member 102. In this case, since the outer outflow portion 32 is closer to one end (front side) than the annular member 102, the distance between the driving mechanism 84 and the outer outflow portion 32 is small. Therefore, the head casing 62 can be easily cooled by the airflow flowing to the outer outflow portion 32, and therefore, the driving mechanism 84 can be efficiently cooled. Further, since at least a part of the outer outflow portion 32 is closer to the front side than the output shaft 90, the air can easily go to the front side of the head casing 62, and therefore, the cooling efficiency for the head casing 62 can be enhanced.
• In the electric tool 10, the airflow flown from the outer inflow portion 28 into the outer housing 22 cools the motor casing 44 and the head casing 62, or cools only the head casing 62, and then, flows out from the outer outflow portion 32. In this case, since the outer inflow portion 28 is arranged between the controller 96 and the motor 72, the volume of the airflow flowing from the outer inflow portion 28 to the controller 96 is smaller than the volume of the airflow flowing from the outer inflow portion 28 to the motor casing 44 and the head casing 62. Therefore, the controller 96 can be suppressed from being cooled by the airflow.
• In the electric tool 10, the air passing through the outside (particularly the upper side and the lower side) of the inner housing 42 is guided inward by the guide portion 105. The air moved inward by the guide portion 105 easily hits the attachment-receiving portion 54, particularly the heatsink 54A, and therefore, the attachment-receiving portion 54 can be efficiently cooled, the ball bearing 78 can be indirectly cooled, and the transmission members (such as the annular member 102 and the swinging arm 87) connected thereto can be also cooled. Therefore, endurance of the transmission members can be improved, and the workability can be improved. Also, since the guide portion 105 and the attachment-receiving portion 54 (particularly the heatsink 54A) are at the same position in the front and back direction, and therefore, the air guided by the guide portion 105 efficiently hits the attachment-receiving portion 54 (particularly the heatsink 54A), and the workability can be further improved. Also, the guide portion 105 is mainly arranged on the upper and lower inner surfaces of the outer housing 22. Therefore, the air passing through the right side and the left side of the inner housing 42 of the air passing through the outside thereof is not moved inward by the guide portion 105. In this manner, the air passing through the right side and the left side of the inner housing 42 can preferentially cool a periphery of the elastic portion supported by the right and left side surfaces, and the air (B3, B4) passing through the upper side and the lower side thereof can preferentially cool the attachment-receiving portion 54. Also, in the electric tool 10, the outer outflow portion 32 is arranged on the upper side and the lower side of the outer housing 22. In this case, the air passing through the upper side and the lower side of the inner housing 42 is moved away from the outer outflow portion 32 by the guide portion 105. More specifically, the airflow B3 is moved downward by the guide portion 105, and therefore, is moved away from the first outflow portion 34, and the airflow B4 is moved upward by the guide portion 105, and therefore, is moved away from the second outflow portion 36. By such a configuration, a wide region of the head casing 62 can be cooled. Particularly, the air moves to get close to the elastic portion (rubber member 98), and therefore, can cool the periphery of the elastic portion.
[Modification Example of Present Embodiment]
• The present invention is not limited to the foregoing embodiments, and various modifications can be made within the scope of the present invention.
• In the electric tool 10, the number of the inflow ports 57A between the stator support portion 48 and the inner outflow portion 58 may be one or more.
• The outer outflow portion 32 is not limited to include the first outflow portion 34 and the second outflow portion 36, but may include only the first outflow portion 34 or only the second outflow portion 36. Also, the outer outflow portion 32 may include three or more outflow portions.
• The tip portion 107 may be farther from the inner housing 42 than the tip portion 109. This is because the small distance between the first wall 106 and the second wall 108 in the front and back direction can limit the airflow. The front surface 106A of the first wall 106 may be at the same position as that of the back end surface of the outflow port 59. At the time of the stoppage of the operation of the motor 72, the distance d may be larger than 10 mm. Also, at the time of the stoppage of the operation of the motor 72, the distance d may be equal to or larger than the opening width W.
• The front end surface 76A may be not positioned between the inflow port 57A and the vertical wall 52 in the front and back direction. The position of the back surface 108B may be not equal to the position of the front end of the inflow port 57A.
• The second wall 108 may be provided as a separate body from the motor casing 44. The first wall 106 may be provided as a separate body from the outer housing 22.
• The outer housing 22 supports the motor casing 44 through the rubber member 29, and the head casing 62 may be distant from the outer housing 22 and be attached to the motor casing 44.
• The elastic portion is not limited to the rubber member 29, and a spring member may be used. The rubber member 29 may be only on either the first flow path 25 side or the second flow path 27 side.
• The outer outflow portion 32 may be not closer to one end side of the shaft direction than the annular member 102. The outer inflow portion 26 may be not positioned between the controller 96 and the motor 72. The outer outflow portion 32 may not face the head casing 62.
• Each of the first wall 106 and the second wall 108 is not limited to have the plate shape, and may have a forward- or backward-curved wall shape.
• The limiter portion 104 may be configured to include two walls facing each other in the front and back direction, and may be not limited to the above-described embodiments such that this is made of two protruding walls. For example, a rib (convex portion) protruding from the outer housing 22 and a groove (concave portion) arranged on the inner housing 42 may face each other in the front and back direction while fitting with each other to have a gap therebetween. That is, a labyrinth portion may be made of the engagement of the convex and concave portions. In this case, the positions of the convex and concave portions may invert.
EXPLANATION OF REFERENCE CHARACTERS
• 10: electric tool, 12: battery pack, 14: tip tool, 16: clamp lever, 17: pin, 18: trigger, 21: push piece, 22: outer housing, 22A: upper wall, 22B: lower wall, 22C: front wall, 22D: outer surface, 22E: inner surface, 23: right housing, 24: left housing, 25: first flow path, 26: outer inflow portion, 26A: inflow port, 27: second flow path, 28: outer inflow portion, 28A: inflow port, 29: rubber member, 32: outer outflow portion, 34: first outflow portion, 36: second outflow portion, 42: inner housing, 44: motor casing, 46: casing main body, 46A: inner circumferential surface, 46B: outer circumferential surface, 47: screw, 48: stator support portion, 49: stator support portion, 52: vertical wall, 52A: front surface, 52B: back surface, 54: attachment-receiving portion, 54A: heatsink, 56: inner inflow portion, 57A: inflow port, 57B: inflow port, 58: inner outflow portion, 59: outflow port, 62: head casing, 63: cylindrical portion, 63A: outer circumferential surface, 64: attachment portion, 65: groove, 66: edge, 68: joint, 71, ball bearing, 72: motor, 74: rotary shaft, 75: rotor, 76: stator, 76A: front end surface, 77: spindle, 78: ball bearing, 82: fan, 84: driving mechanism, 86: eccentric shaft, 87: swinging arm, 87A: arm portion, 88: unit casing, 90: output shaft, 91: shaft holder, 92: coil spring, 94: fixing screw, 96: controller, 98: rubber member, 99: protruding portion, 102: annular member, 104: limiter portion, 105: guide portion, 106: first wall, 106A: front surface, 106B: back surface, 107: tip portion, 108: second wall, 108A: front surface, 108B: back surface, 109: tip portion, d: distance, G1: graph, G2: graph, G3: graph, K0: dotted line, K1: dotted line, K2: dotted line, K3: dotted line, L1: overlap amount, M1: front wall surface, M2: back wall surface, S: space, S1: first space, S2: second space, T1: thickness, T2: thickness, T3: thickness, V: flow path, W: opening width

Claims (15)

1. A work machine comprising:

   a motor;

   a fan generating airflow when being rotated by the motor;

   an inner casing provided with an inner inflow portion and an inner outflow portion, and including a motor accommodating portion for accommodating the motor and a mechanism accommodating portion for accommodating a driving mechanism driven by operation of the motor;

   an outer casing provided with an outer inflow portion and an outer outflow portion, and accommodating the inner casing while supporting the inner casing through an elastic portion;
   and

   a limiter portion positioned between the inner inflow portion and the inner outflow portion to limit the airflow flowing between the inner casing and the outer casing,

   wherein the outer inflow portion, the inner inflow portion, the inner outflow portion and the outer outflow portion are positioned such that the air flows into the motor accommodating portion through the outer inflow portion and the inner inflow portion while the air flows out from the outer outflow portion through the inner outflow portion and a gap between the outer casing and the mechanism accommodating portion, and,

   in a direction in which the fan and the motor are arranged, in which the direction is defined as an arrangement direction, the limiter portion includes:

   a first wall protruding from the outer casing toward the inner casing; and

   a second wall arranged between the first wall and the inner inflow portion in the arrangement direction, and protruding from the inner casing toward the outer casing.
2. The work machine according to claim 1,
   wherein, in a direction crossing the arrangement direction, in which the direction is defined as a crossing direction, a tip portion of the first wall is closer to the inner casing than a tip portion of the second wall in the crossing direction.
3. The work machine according to claim 1,
   wherein the first wall is closer to the inner inflow portion than the inner outflow portion in the arrangement direction.
4. The work machine according to claim 1,

   wherein a distance between the first wall and the second wall in the arrangement direction differs between a distance at time of operation of the motor and a distance at time of stoppage of the operation of the motor, and

   the distance at the time of the stoppage of the operation of the motor is equal to or smaller than 10 mm.
5. The work machine according to claim 1,

   wherein a distance between the first wall and the second wall in the arrangement direction differs between a distance at time of operation of the motor and a distance at time of stoppage of the operation of the motor, and

   the distance at the time of the stoppage of the operation of the motor is smaller than an opening width of the inner outflow portion in the arrangement direction.
6. The work machine according to claim 1,

   wherein the motor accommodating portion is provided with a stator support portion for supporting a stator of the motor,

   the inner inflow portion includes a plurality of inflow ports, and

   at least one inflow port of the plurality of inflow ports is positioned between the stator support portion and the inner outflow portion in the arrangement direction.
7. The work machine according to claim 6,

   wherein the inner casing is provided with a vertical wall extending to a gap between the stator and the fan, and

   an end surface of the stator, the end surface being on the fan side, is positioned between the inflow port and the vertical wall in the arrangement direction.
8. The work machine according to claim 7,
   wherein a position of an end surface of the second wall, the end surface being on the inflow port side, is aligned with a position of an end surface of the inflow port, the end surface being on the second wall side.
9. The work machine according to claim 1,
   wherein the limiter portion includes a labyrinth portion.
10. The work machine according to claim 1,
    wherein at least a part of the first wall and a part of the second wall overlap each other when being viewed in the arrangement direction.
11. The work machine according to claim 1,

    wherein the fan is a centrifugal fan rotating around a shaft of the motor as a center,

    a first flow path on one side in a crossing direction crossing the arrangement direction and a second flow path on the other side in the crossing direction are arranged between the outer casing and the inner casing, and

    the elastic portion is positioned between the first flow path and the second flow path in the crossing direction.
12. The work machine according to claim 11,

    wherein a space between the mechanism accommodating portion and the outer casing is divided into a first space and a second space in the crossing direction by the elastic portion, and

    the outer outflow portion includes at least one of a first outflow portion in which air can flow out from the first space and a second outflow portion in which air can flow out from the second space.
13. The work machine according to claim 1,

    wherein a shaft of the motor is provided with a transmission member for transmitting a driving force to the driving mechanism, and

    the outer outflow portion is closer to the driving mechanism than the transmission member.
14. The work machine according to claim 1,

    wherein the arrangement direction is a front and back direction,

    the motor is closer to a back side than the fan,

    a controller for controlling the operation of the motor is arranged inside the outer casing,

    the controller is closer to the back side than the motor,

    the outer inflow portion is positioned between the controller and the motor in the front and back direction, and

    the outer outflow portion is closer to a front side than the fan, and faces the mechanism accommodating portion.
15. A work machine comprising:

    a motor;

    a fan generating airflow when being rotated by the motor;

    an inner casing provided with an inner inflow portion and an inner outflow portion, and including a motor accommodating portion for accommodating the motor and a mechanism accommodating portion for accommodating a driving mechanism driven by operation of the motor;

    an outer casing provided with an outer inflow portion and an outer outflow portion, and accommodating the inner casing while supporting the inner casing through an elastic portion;
    and

    a limiter portion positioned between the inner inflow portion and the inner outflow portion to limit the airflow flowing between the inner casing and the outer casing,

    wherein the outer inflow portion, the inner inflow portion, the inner outflow portion and the outer outflow portion are positioned such that the air flows into the motor accommodating portion through the outer inflow portion and the inner inflow portion while the air flows out from the outer outflow portion through the inner outflow portion and a gap between the outer casing and the mechanism accommodating portion, and,

    in a direction in which the fan and the motor are arranged, in which the direction is defined as an arrangement direction, the limiter portion includes:

    a first wall arranged on the outer casing; and

    a second wall arranged on the inner casing and facing the first wall in the arrangement direction.