Work Machine

Abstract

To provide a technology for cooling a control unit.SOLUTION: A work machine includes: a motor that drives a work part; a fan driven by the motor for forming an air flow in a first space; a control unit arranged in the first space; a barrier wall that separates the first space and a second space; a first opening formed in the barrier wall for communicating the first space and the second space; and a rib extending from the barrier wall in the first space for forming an air passage through which the air flow flows, in between the rib and the control unit. The control unit includes a circuit board that controls driving of the motor, and a case that accommodates the circuit board. The control unit has a first surface facing the rib. When viewed from a first direction orthogonal to the first surface, the rib and the first surface at least partially overlap with each other. With respect to the first direction, the distance between the rib and the first surface is smaller than the thickness of the case.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The technology disclosed in this specification relates to a work machine. [Background technology]

[0002] Patent Document 1 discloses a working machine. The working machine includes a motor that drives a working part, a fan that is driven by the motor and forms an air flow in a first space, a control unit arranged in the first space, a partition wall that separates the first space from a second space, and a first opening that is formed in the partition wall and communicates between the first space and the second space. The control unit includes a circuit board that controls the driving of the motor, and a case that houses the circuit board. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-179523 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned work machine, the circuit board generates heat when controlling the drive of the motor. As a result, the entire control unit generates heat. When the fan rotates, air flows into the first space through the first opening. The air flows along the control unit, thereby cooling the control unit. As the amount of current flowing through the circuit board increases, the amount of heat generated by the circuit board increases, and it is therefore desirable to improve the cooling performance of the control unit. This specification provides a technology that can improve the cooling performance of the control unit. [Means for solving the problem]

[0005] This specification discloses a working machine. The working machine includes a motor for driving a working part, a fan driven by the motor to form an air flow in a first space, a control unit arranged in the first space, a partition wall separating the first space from a second space, a first opening formed in the partition wall and communicating the first space with the second space, and a rib extending from the partition wall in the first space and forming an air passage through which the air flow passes between the control unit and the control unit. The control unit includes a circuit board for controlling the driving of the motor, and a case for accommodating the circuit board. The control unit has a first surface facing the rib. When viewed from a first direction perpendicular to the first surface, the rib and the first surface at least partially overlap each other. In the first direction, the distance between the rib and the first surface is smaller than the thickness of the case.

[0006] In the above configuration, when the fan rotates, air in the second space flows into the first space from the first opening. The air then passes through an air passage between the rib and the first surface of the control unit and flows to the motor. With the above configuration, the distance between the rib and the first surface in the first direction is smaller than the thickness of the case, so that the flow rate of the air flowing between the rib and the first surface can be increased compared to when the distance between the rib and the first surface in the first direction is greater than the thickness of the case. The increased heat transfer rate can improve the cooling performance of the control unit. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a perspective view of the working machine 2 of the embodiment as viewed from the rear right side. [Diagram 2] FIG. 2 is a side view of the working machine 2 of the embodiment as viewed from the left side. [Diagram 3] 2 is a horizontal cross-sectional view of the vicinity of a motor 34 of the working machine 2 of the embodiment. [Figure 4] 2 is a horizontal cross-sectional view of the vicinity of a transmission mechanism 40 of the working machine 2 of the embodiment. [Diagram 5] 2 is a vertical cross-sectional view of the vicinity of a fan 38 of the working machine 2 of the embodiment. [Figure 6]2 is a perspective view of a transmission mechanism 40, an intermediate shaft 42, and a sprocket 44 of the working machine 2 of the embodiment. [Figure 7] 2 is a cross-sectional view of the vicinity of a control unit 70 of the working machine 2 of the embodiment. [Figure 8] 2 is a vertical cross-sectional view of the vicinity of a control unit 70 of the working machine 2 of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Representative and non-limiting examples of the present invention are described in detail below with reference to the drawings. This detailed description is intended simply to provide those skilled in the art with details for implementing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Additionally, the additional features and inventions disclosed can be used separately or together with other features and inventions to provide further improved working machines.

[0009] In addition, the combinations of features and steps disclosed in the following detailed description are not essential for implementing the present invention in the broadest sense, but are specifically described only to illustrate representative embodiments of the present invention. Furthermore, the various features of the following representative embodiments and the various features described in the claims do not have to be combined in the exact manner of the embodiments described herein or in the order listed in order to provide additional and useful embodiments of the present invention.

[0010] All features described in the specification and / or claims are intended to be disclosed individually and independently of one another as limitations to the specific features described in the original disclosure and claims, apart from the configuration of features described in the examples and / or claims. Furthermore, all numerical ranges and group or aggregate descriptions are intended to disclose intermediate configurations thereof as limitations to the specific features described in the original disclosure and claims.

[0011] In one or more embodiments, the control unit may further include a heat sink for dissipating heat. The heat sink may be exposed to the air passage.

[0012] In the above configuration, heat from the control unit is dissipated to the air flowing through the air passage via the heat dissipation section, thereby making it possible to improve the cooling performance of the control unit compared to a case in which the control unit does not include a heat dissipation section.

[0013] In one or more embodiments, the heat dissipation portion may have an uneven shape.

[0014] In the above configuration, the area where air can come into contact with the heat dissipation portion is larger than in a case where the heat dissipation portion does not have an uneven shape, which can further improve the cooling performance of the control unit.

[0015] In one or more embodiments, the ribs may be disposed generally parallel to the first surface.

[0016] For example, when the ribs are inclined toward the first surface, the length of the ribs must be adjusted so that the distance between the ribs and the first surface does not become less than a certain distance, and therefore the air passage cannot be made longer. On the other hand, when the ribs are inclined toward the first surface, the distance between the ribs and the first surface gradually increases in the first direction. As a result, the flow rate of the air decreases as the air that flows in from the first opening flows through the air passage. In the above configuration, the ribs are disposed approximately parallel to the first surface, so that the flow rate of the air that flows in from the first opening can be prevented from decreasing, and the air passage can be made longer.

[0017] In one or more embodiments, the rib may have opposing portions that face an area of ​​at least ⅓ of the area of ​​the first surface.

[0018] In the above configuration, the first surface can be cooled over a wide range by the air flowing in from the first opening.

[0019] In one or more embodiments, the ribs may be integrally formed with the septum.

[0020] In the above configuration, the number of parts can be reduced compared to a case in which the rib and the partition wall are separate.

[0021] In one or more embodiments, the control unit may be disposed along a plane generally perpendicular to the bulkhead.

[0022] If the control unit is not disposed along a plane substantially perpendicular to the partition wall, the air flowing in from the first opening will bend before flowing through the air passage between the rib and the first surface. As a result, the air flow will bend, and the air flow speed will decrease. In the above configuration, the air flowing in from the first opening will flow through the air passage between the rib and the first surface without bending. This makes it possible to suppress a decrease in the air flow speed.

[0023] In one or more embodiments, the second space may be a space external to the work machine.

[0024] In the above configuration, the relatively low-temperature air outside the working machine can be introduced into the first space through the first opening, thereby improving the cooling performance of the control unit.

[0025] In one or more embodiments, a width of the first opening in the first direction may be less than a thickness of the case.

[0026] There may be foreign objects present in the area where the work machine is used. In the above configuration, since the width of the first opening in the first direction is smaller than the thickness of the case, it is possible to prevent the foreign objects from entering the first space through the first opening.

[0027] In one or more embodiments, the work machine may further include a second opening formed in the partition wall and communicating between the first space and the second space. The rib may be connected to a portion of the partition wall between the first opening and the second opening.

[0028] For example, if only the first opening is formed in the partition wall, the air flowing in from the first opening cools the control unit, and the air warmed by cooling the control unit flows toward the motor. This may result in insufficient cooling of the motor. In the above configuration, the air flowing in from the second opening flows toward the motor without cooling the control unit because the rib is disposed between the first opening and the second opening. The air flowing in from the first opening can improve the cooling of the control unit, and the air flowing in from the second opening can improve the cooling of the motor.

[0029] In one or more embodiments, the work machine may further include a guide bar. The working unit may include a sprocket that is rotated by driving the motor, and a saw chain that runs around the periphery of the guide bar as the sprocket rotates.

[0030] In the above configuration, when the saw chain cuts the workpiece, a large load acts on the motor, and a large current flows through the circuit board. This causes a large amount of heat to be generated by the circuit board, and as a result, the control unit is prone to becoming hot. With the above configuration, air with a high flow rate can be kept in contact with the first surface of the case of the control unit, which has become hot. By increasing the heat transfer rate, the cooling performance of the control unit, which has become hot, can be improved.

[0031] (Example) A working machine 2 of the embodiment will be described with reference to Figs. 1 to 8. The working machine 2 is a chain saw. As shown in Fig. 1, the working machine 2 includes a main body 4, a guide bar 6, and a saw chain 8. The guide bar 6 has a long and thin plate shape. The guide bar 6 is attached to the main body 4 so as to protrude forward from the main body 4. The saw chain 8 includes a plurality of cutters connected to each other. The saw chain 8 is attached along the periphery of the guide bar 6. A battery pack B is detachably attached to the main body 4. The working machine 2 rotates the saw chain 8 along the periphery of the guide bar 6 by power supplied from the battery pack B, and cuts a workpiece such as wood. In the following, when the working machine 2 is placed on a placement surface P (see Fig. 2) such as the ground, a direction perpendicular to the placement surface P is called the up-down direction, a direction in which the longitudinal direction of the guide bar 6 is projected onto the placement surface P is called the front-rear direction, and a direction perpendicular to the up-down direction and the front-rear direction is called the left-right direction.

[0032] The main body 4 includes a housing 10, a front handle 18, a hand guard 20, and a sprocket cover 22. The housing 10 includes a left housing 12 that defines the outer shape of the left half of the housing 10, and a right housing 14 that defines the outer shape of the right half of the housing 10. A rear handle 16 is formed at the rear of the housing 10 for an operator to hold with his or her hand. A trigger switch 24 is disposed on the rear handle 16 to allow the operator to operate the rotation drive of the saw chain 8.

[0033] The front handle 18 extends upward from the left wall of the left housing 12, then bends to the right and extends toward the right side, and then bends downward and extends downward to connect to the right wall of the right housing 14. The operator can handle the work machine 2 by holding the rear handle 16 with one hand and the front handle 18 with the other hand.

[0034] The hand guard 20 is attached to the upper front part of the housing 10. When the hand guard 20 is tilted forward while the saw chain 8 is rotating around the periphery of the guide bar 6, the rotational drive of the saw chain 8 is braked.

[0035] The sprocket cover 22 is attached to the right wall of the right housing 14. The rear portion of the guide bar 6 is disposed between the sprocket cover 22 and the right housing 14.

[0036] 2, an oil filler port 28 of the oil tank 26 protrudes from the left wall of the left housing 12 to the outside of the housing 10. A cap 30 is attached to the oil filler port 28. The oil tank 26 contains oil for lubricating the saw chain 8.

[0037] As shown in FIG. 3 and FIG. 4, the working machine 2 includes a motor 34, a motor housing 36, a cover member 37, a fan 38, a transmission mechanism 40, an intermediate shaft 42, and a sprocket 44. The motor 34, the motor housing 36, the fan 38, the cover member 37, and the transmission mechanism 40 are disposed inside the housing 10. Hereinafter, the space inside the housing 10 is referred to as an internal space 11. As shown in FIG. 3, the motor 34 is disposed rearward of the oil tank 26. The motor 34 is an inner rotor type DC brushless motor. In addition, in a modified example, the motor 34 may be an outer rotor type motor, a brushed motor, or an AC motor. The motor 34 includes a stator 50 around which a coil 48 is wound, a rotor 51 disposed inside the stator 50 and equipped with a permanent magnet, and a motor shaft 52 that penetrates the center of the rotor 51 and is fixed to the rotor 51. The coil 48 is electrically connected to a control unit 70 (see FIG. 7). The stator 50 is fixed to the motor housing 36. The motor housing 36 is fixed to the housing 10. A first air hole 36a is formed in the left wall of the motor housing 36, and a second air hole 36b is formed in the right wall of the motor housing 36. A cover member 37 is attached to the right wall of the motor housing 36. The motor shaft 52 is disposed along the left-right direction. The motor shaft 52 is rotatably supported by the motor housing 36 via a bearing 54, and is rotatably supported by the cover member 37 via a bearing 56.

[0038] A discharge passage 37a is defined between the motor housing 36 and the cover member 37. The discharge passage 37a communicates with the space inside the motor housing 36 via a second air hole 36b. As shown in FIG. 5, the discharge passage 37a communicates with the space outside the work machine 2 via a discharge port 10a formed in the bottom wall of the housing 10. Hereinafter, the space outside the work machine 2 will be referred to as the external space 3.

[0039] The fan 38 is fitted onto the motor shaft 52. The fan 38 is disposed in the exhaust passage 37a. The fan 38 rotates in conjunction with the rotation of the motor shaft 52, and air flows downward.

[0040] 6, the transmission mechanism 40 includes a first gear 60 and a second gear 62. The first gear 60 is fitted to the right end of the motor shaft 52. The first gear 60 is engaged with the second gear 62. The rotation shaft of the second gear 62 is disposed forward and below the rotation shaft of the first gear 60.

[0041] The intermediate shaft 42 is inserted into the second gear 62. As shown in Fig. 4, the intermediate shaft 42 is disposed along the left-right direction. The intermediate shaft 42 is rotatably supported with respect to the cover member 37 via a bearing 64, and is rotatably supported with respect to the housing 10 via a bearing 66.

[0042] The sprocket 44 is fitted to the right end of the intermediate shaft 42. The saw chain 8 is stretched over the sprocket 44 from the guide bar 6. When the motor 34 is driven, the first gear 60 rotates in conjunction with the rotation of the motor shaft 52, and the second gear 62 rotates. Next, the sprocket 44 rotates together with the intermediate shaft 42. This causes the saw chain 8 to rotate along the periphery of the sprocket 44 and the guide bar 6.

[0043] As shown in Fig. 7, the work machine 2 includes a control unit 70. The control unit 70 is fixed to the right housing 14. Specifically, the right housing 14 includes a fixing rib 14a extending from the inner surface toward the left side. As shown in Fig. 8, the fixing rib 14a abuts against the control unit 70 from above and also abuts against the control unit 70 from below. As shown in Fig. 7, the control unit 70 is disposed along a plane extending along the left-right direction and the front-rear direction.

[0044] The control unit 70 includes a circuit board 72, a case 74, and a potting material 76. The circuit board 72 is disposed along a plane that is substantially perpendicular to the left wall of the left housing 12. Here, the plane that is substantially perpendicular to the left wall of the left housing 12 includes a surface that is inclined at an angle of 1.5 degrees or less with respect to the left wall of the left housing 12. The circuit board 72 is accommodated in a case 74. The circuit board 72 includes a plurality of switching elements (not shown) and a microcomputer (not shown). The switching elements are, for example, IGBTs or MOSFETs. The microcomputer controls the operation of the motor 34 by switching the switching elements between an on state and an off state.

[0045] The case 74 has a box shape that is open on the lower side. An upper surface 74a of the case 74 defines the upper surface of the control unit 70. Hereinafter, the upper surface of the control unit 70 may be denoted by the reference symbol 74a. The upper surface 74a of the case 74 is perpendicular to the vertical direction. The case 74 is made of, for example, a metal material (for example, aluminum). In a modified example, the case 74 may be made of, for example, a resin material. The case 74 includes a heat dissipation section 78. The heat dissipation section 78 is formed in a left portion of the upper surface 74a of the case 74. The heat dissipation section 78 has an uneven shape in which a plurality of protrusions are formed in a portion recessed from the upper surface 74a of the case 74. In the vertical direction, the inner surface of the case 74 in the region where the heat dissipation section 78 is formed is disposed closer to the circuit board 72 than the inner surface of the case 74 in the region where the heat dissipation section 78 is not formed. This makes it easier for heat from the circuit board 72 to be transferred to the heat dissipation section 78. The width We1 of the heat dissipation portion 78 in the left-right direction is equal to or greater than 20% of the width Wc1 of the case 74 in the left-right direction, and in this embodiment, the width We1 is 30% of the width Wc1.

[0046] The potting material 76 is made of, for example, a resin material. The potting material 76 is poured into the inside of the case 74 in a molten state and solidifies to be disposed inside the case 74. The potting material 76 encloses the circuit board 72 therein. A lower surface 76a of the potting material 76 defines the lower surface of the control unit 70. Hereinafter, the lower surface of the control unit 70 may be denoted by the reference symbol 76a.

[0047] As shown in FIG. 2, two first openings 90 and two second openings 92 are formed in the left wall of the left housing 12. Hereinafter, the left wall of the left housing 12 may be referred to as the partition wall 13. The partition wall 13 is disposed on a plane along the up-down direction and the front-rear direction. The first opening 90 and the second opening 92 are disposed forward of the rear handle 16 and above the battery pack B. The first opening 90 and the second opening 92 penetrate the partition wall 13 in the left-right direction. As a result, the first opening 90 and the second opening 92 communicate with the external space 3 and the internal space 11 (see FIG. 7). The two first openings 90 are aligned in the front-rear direction. The two second openings 92 are aligned in the front-rear direction. Each of the second openings 92 is disposed above the first opening 90. The first opening 90 has a rectangular shape in which the width Wp1 in the up-down direction is shorter than the width Wp2 in the front-rear direction. The second opening 92 has a rectangular shape with a width Wp3 in the vertical direction shorter than a width Wp2 in the front-rear direction. As shown in FIG. 7, the two first openings 90 and the two second openings 92 are disposed above the upper surface 74a of the case 74. The vertical width Wp1 of the first opening 90 and the vertical width Wp3 of the second opening 92 are 50% or less of the vertical thickness Tc1 of the case 74 (i.e., the distance between the upper surface 74a of the case 74 and the lower surface 76a of the potting material 76), and in this embodiment, the widths Wp1 and Wp3 are 20% of the thickness Tc1. Foreign matter, such as chips, is prevented from flowing into the internal space 11 from the first opening 90 and the second opening 92. As shown in FIG. 8, the position of the front end of the control unit 70 is substantially the same as the position of the front end of the first opening 90 on the front side in the front-rear direction. In the front-rear direction, the position of the rear end of the control unit 70 is disposed rearward of the position of the rear end of the first opening 90 on the rear side.

[0048] As shown in FIG. 7, the working machine 2 further includes a rib 100. The rib 100 is disposed in the internal space 11. The rib 100 extends from the partition wall 13 toward the right side. Here, the partition wall 13 separates the internal space 11 from the external space 3. The rib 100 extends substantially parallel to the left-right direction. Here, the rib 100 extending substantially parallel to the left-right direction includes the rib 100 being inclined at an angle of 1.5 degrees or less with respect to the left-right direction. When forming the rib 100 by resin molding, the mold can be easily removed. In a modified example, the rib 100 may be inclined at an angle of 10 degrees or less with respect to a plane along the left-right direction and the front-rear direction. The rib 100 extends to the vicinity of the boundary between the left housing 12 and the right housing 14 in the left-right direction. In this embodiment, the width of the rib 100 in the left-right direction is greater than twice the thickness of the partition wall 13 in the left-right direction. The rib 100 is formed integrally with the partition wall 13. In a modified example, the rib 100 may be fixed to the partition wall 13 using a bolt or the like. The rib 100 is connected to a portion 94 between the first opening 90 and the second opening 92 of the partition wall 13 in the vertical direction. The rib 100 defines a lower space between the rib 100 and the upper surface 74a of the case 74, and an upper space between the rib 100 and the upper inner surface of the left housing 12. The lower space and the upper space are each a part of the internal space 11. The lower space communicates with the external space 3 through the first opening 90. The upper space communicates with the external space 3 through the second opening 92. The rib 100 partially overlaps with the case 74 in the vertical direction. Hereinafter, the portion of the rib 100 that overlaps with the case 74 will be referred to as a facing portion 102.

[0049] The facing portion 102 faces the upper surface 74a of the case 74 and the heat dissipation portion 78. A distance L1 between the facing portion 102 and the upper surface 74a of the case 74 is substantially constant in the left-right direction. The distance L1 is smaller than the thickness Tc1 of the case 74. A width Wr1 in the left-right direction of the facing portion 102 is 30% or more of a width Wc1 in the left-right direction of the case 74, and in this embodiment, the width Wr1 is 45% of the width Wc1. The facing portion 102 faces an area of ​​1 / 3 or more (i.e., 33% or more) of the area of ​​the upper surface 74a of the case 74, and in this embodiment, the facing portion 102 faces an area of ​​40% of the upper surface 74a of the case 74. As shown in FIG. 8, the width in the front-rear direction of the facing portion 102 is substantially the same as the distance from the rear end of the first opening 90 on the rear side to the front end of the first opening 90 on the front side. The distance from the upper end of the second opening 92 to the upper surface 74a of the case 74 is equal to or less than 100% of the thickness Tc1 of the case 74, and in this embodiment, the distance is 80% of the thickness Tc1.

[0050] Next, the air flow when the fan 38 rotates will be described. When the fan 38 (see FIG. 3) rotates, negative pressure is generated on the left side of the fan 38. As a result, as shown in FIG. 7, air from the external space 3 flows into the internal space 11 from both the first opening 90 and the second opening 92. In the drawing, the direction of the air flow is illustrated by an arrow. The air flowing in from the first opening 90 passes through the lower space, that is, the air passage AP between the facing part 102 and the upper surface 74a of the case 74, and flows to the internal space 11 on the right side of the tip of the facing part 102. Since the heat dissipation part 78 is exposed to the air passage AP, while the air flows along the heat dissipation part 78, the heat of the control unit 70 is dissipated from the heat dissipation part 78 to the air. This cools the control unit 70. The air flowing in from the second opening 92 passes through the upper space, that is, between the facing part 102 and the upper inner surface of the left housing 12. Then, this air flows to the internal space 11 on the right side of the tip of the facing part 102, and merges with the air flowing through the air passage AP. The temperature of the merged air is lower than the temperature of the air that has flowed through the air passage AP. The merged air changes its flow direction to the front and flows toward the motor housing 36 (see FIG. 3).

[0051] As shown in FIG. 3, the joined air flows along the outer circumferential surface of the motor housing 36, and then flows into the motor housing 36 from the first air hole 36a. The flowing air flows inside the motor 34 (i.e., between the stator 50 and the rotor 51). While the air flows inside the motor 34, heat generated in the motor 34 is dissipated to the air. This cools the motor 34. The air then flows into the exhaust passage 37a from the second air hole 36b. As shown in FIG. 5, the air that has flowed into the exhaust passage 37a is blown downward by the rotation of the fan 38. The blown air is exhausted to the external space 3 from the exhaust port 10a of the housing 10.

[0052] (effect) The working machine 2 of this embodiment includes a motor 34 that drives the sprocket 44 and the saw chain 8, a fan 38 that is driven by the motor 34 and forms an air flow in the internal space 11, a control unit 70 arranged in the internal space 11, a partition wall 13 that separates the internal space 11 from the external space 3, a first opening 90 that is formed in the partition wall 13 and communicates the internal space 11 with the external space 3, and a rib 100 that extends from the partition wall 13 in the internal space 11 and forms an air passage AP through which the air flow passes between the control unit 70 and the control unit 70. The control unit 70 includes a circuit board 72 that controls the drive of the motor 34, and a case 74 that houses the circuit board 72. The control unit 70 has an upper surface 74a that faces the rib 100. When viewed from a vertical direction perpendicular to the upper surface 74a, the rib 100 and the upper surface 74a at least partially overlap each other. In the vertical direction, a distance L1 between the rib 100 and the upper surface 74a is smaller than a thickness Tc1 of the case 74.

[0053] In the above configuration, when the fan 38 rotates, air in the external space 3 flows into the internal space 11 from the first opening 90. The air then passes through the air passage AP between the rib 100 and the upper surface 74a of the control unit 70 and flows to the motor 34. According to the above configuration, the distance L1 between the rib 100 and the upper surface 74a in the vertical direction is smaller than the thickness Tc1 of the case 74, so that the flow rate of the air flowing between the rib 100 and the upper surface 74a can be increased compared to the case where the distance L1 between the rib 100 and the upper surface 74a in the vertical direction is larger than the thickness Tc1 of the case 74. The increased heat transfer rate can improve the cooling performance of the control unit 70.

[0054] The control unit 70 further includes a heat dissipation section 78 that dissipates heat. The heat dissipation section 78 is exposed to the air passage AP.

[0055] In the above configuration, heat from the control unit 70 is dissipated to the air flowing through the air passage AP via the heat dissipation section 78. This allows the control unit 70 to be cooled more efficiently than if the control unit 70 were not provided with the heat dissipation section 78.

[0056] Moreover, the heat dissipation portion 78 has an uneven shape.

[0057] In the above configuration, compared to a case where the heat dissipation portion 78 does not have an uneven shape, the area where air can come into contact with the heat dissipation portion 78 is larger, thereby making it possible to further improve the cooling performance of the control unit 70.

[0058] Moreover, the ribs 100 are disposed substantially parallel to the upper surface 74a.

[0059] For example, when the rib 100 is inclined toward the upper surface 74a, the length of the rib 100 must be adjusted so that the distance between the rib 100 and the upper surface 74a does not become less than a certain distance, and therefore the air passage AP cannot be made longer. On the other hand, when the rib 100 is inclined away from the upper surface 74a, the distance between the rib 100 and the upper surface 74a gradually increases. Therefore, the flow rate of the air decreases as the air that flows in from the first opening 90 flows through the air passage AP. In the above configuration, the rib 100 is disposed approximately parallel to the upper surface 74a, so that the flow rate of the air that flows in from the first opening 90 can be prevented from decreasing, and the air passage AP can be made longer.

[0060] The rib 100 also has a facing portion 102 that faces an area of ​​at least ⅓ of the area of ​​the upper surface 74a.

[0061] In the above configuration, the air flowing in from the first openings 90 can cool the upper surface 74a over a wide range.

[0062] Moreover, the rib 100 is formed integrally with the partition wall 13 .

[0063] In the above-described configuration, the number of parts can be reduced compared to a case in which the rib 100 and the partition wall 13 are separate bodies.

[0064] The control unit 70 is disposed along a plane that is approximately perpendicular to the partition wall 13 .

[0065] If the control unit 70 is not disposed along a plane substantially perpendicular to the partition wall 13, the air flowing in from the first opening 90 passes through the air passage AP between the rib 100 and the upper surface 74a after bending. Therefore, the air flow speed decreases as the air flow bends. In the above configuration, the air flowing in from the first opening 90 passes through the air passage AP between the rib 100 and the upper surface 74a without bending. This makes it possible to suppress a decrease in the air flow speed.

[0066] Moreover, the external space 3 is a space outside the work machine 2 .

[0067] In the above configuration, it is possible for the relatively low-temperature air outside the work machine 2 to flow into the internal space 11 through the first opening 90. This makes it possible to improve the cooling performance of the control unit 70.

[0068] Furthermore, the width Wp1 of the first opening 90 in the up-down direction is smaller than the thickness Tc1 of the case 74.

[0069] Foreign matter may be present in the area where the work machine 2 is used. In the above configuration, since the width Wp1 of the first opening 90 in the vertical direction is smaller than the thickness Tc1 of the case 74, it is possible to prevent foreign matter from entering the internal space 11 through the first opening 90.

[0070] The work machine 2 further includes a second opening 92 formed in the partition wall 13 and communicating the internal space 11 with the external space 3. The rib 100 is connected to a portion 94 between the first opening 90 and the second opening 92 of the partition wall 13.

[0071] For example, if only the first opening 90 is formed in the partition wall 13, the air flowing in from the first opening 90 cools the control unit 70, and the air warmed by cooling the control unit 70 flows toward the motor 34. For this reason, there is a risk that the motor 34 cannot be sufficiently cooled. In the above configuration, the air flowing in from the second opening 92 flows toward the motor 34 without cooling the control unit 70 because the rib 100 is disposed between the first opening 90 and the second opening 92. The air flowing in from the first opening 90 can improve the cooling performance of the control unit 70, and the air flowing in from the second opening 92 can improve the cooling performance of the motor 34.

[0072] The work machine 2 also includes a guide bar 6, a sprocket 44 that rotates when driven by the motor 34, and a saw chain 8 that runs around the periphery of the guide bar 6 as the sprocket 44 rotates.

[0073] In the above configuration, when the saw chain 8 cuts the workpiece, a large load acts on the motor 34, and a large current flows through the circuit board 72. This causes a large amount of heat to be generated by the circuit board 72, and as a result, the control unit 70 is likely to become hot. With the above configuration, the air with a high flow rate can be kept in contact with the upper surface 74a of the case 74 of the control unit 70, which has become hot. By increasing the heat transfer rate, the cooling performance of the control unit 70, which has become hot, can be improved.

[0074] (Correspondence) The sprocket 44 and the saw chain 8 are an example of a "working part." The internal space 11 and the external space 3 are an example of a "first space" and a "second space," respectively. The upper surface 74a is an example of a "first surface." The up-down direction is an example of a "first direction."

[0075] The heat dissipation section 78 according to one embodiment may be formed separately from the case 74. The heat dissipation section 78 may be configured to be attachable to the case 74.

[0076] The rib 100 according to the embodiment does not have to be disposed substantially parallel to the upper surface 74 a of the case 74 .

[0077] The control unit 70 according to an embodiment does not necessarily have to be disposed along a plane substantially perpendicular to the partition wall 13 .

[0078] The second space in one embodiment does not have to be the external space 3. In this case, the work machine 2 may further include a cover member disposed outside the left housing 12, and the second space may be a space formed between the left housing 12 and the cover member.

[0079] The partition wall 13 according to an embodiment does not necessarily have to have the second opening 92 formed therein.

[0080] The work machine 2 according to one embodiment is not limited to a chain saw, and may be, for example, a hedge trimmer or a blower. [Explanation of symbols]

[0081] 2: Work equipment 3: External space 4: Main unit 6: Guide bar 8: Saw chain 10: Housing 11: Interior space 12: Left housing 13: Bulkhead 14: Right side housing 34: Motor 36: Motor housing 36a, 36b: Air holes 37a: Discharge passage 38: Fan 40: Transmission mechanism 44: Sprocket 70: Control unit 72: Circuit board 74: Case 74a:Top surface 76: Potting material 76a: Bottom surface 78: Heat dissipation part 90: First opening 92: Second opening 100: Rib 102: Opposing part AP: Air passage B: Battery pack

Claims

1. A motor that drives the working unit; a fan driven by the motor to form an air flow in the first space; A control unit disposed in the first space; a partition wall separating the first space and the second space; a first opening formed in the partition wall and communicating the first space with the second space; a rib extending from the partition wall in the first space and forming an air passage between the partition wall and the control unit, through which the air flow passes; The control unit A circuit board for controlling the driving of the motor; A case for accommodating the circuit board. the control unit has a first surface facing the rib, When viewed from a first direction perpendicular to the first surface, the rib and the first surface at least partially overlap each other, a distance between the rib and the first surface in the first direction is smaller than a thickness of the case; The rib has an opposing portion that faces an area of ​​the first surface that is equal to or greater than ⅓ of an area of ​​the first surface.

2. The work machine according to claim 1 , wherein the rib is disposed parallel to the first surface or inclined at an angle of 1.5 degrees or less to the first surface.

3. A motor that drives the working unit; a fan driven by the motor to form an air flow in the first space; A control unit disposed in the first space; a partition wall separating the first space and the second space; a first opening formed in the partition wall and communicating the first space with the second space; a rib extending from the partition wall in the first space and forming an air passage between the partition wall and the control unit, through which the air flow passes; The control unit A circuit board for controlling the driving of the motor; A case for accommodating the circuit board. the control unit has a first surface facing the rib, When viewed from a first direction perpendicular to the first surface, the rib and the first surface at least partially overlap each other, a distance between the rib and the first surface in the first direction is smaller than a thickness of the case; The rib is disposed parallel to the first surface or inclined at an angle of 1.5 degrees or less with respect to the first surface, and has an opposing portion opposed to the first surface, A work machine, wherein the dimension of the opposing portion in a second direction, which is the direction in which the rib extends from the partition wall, is 30% or more of the dimension of the control unit in the second direction.

4. The control unit further includes a heat dissipation unit that dissipates heat, The work machine according to claim 1 , wherein the heat dissipation portion is exposed to the air passage.

5. The work machine according to claim 4 , wherein the heat dissipation portion has an uneven shape.

6. The work machine according to claim 1 , wherein the rib is formed integrally with the partition wall.

7. The work machine according to claim 1 , wherein the control unit is disposed along a plane substantially perpendicular to the partition wall.

8. The work machine according to claim 1 , wherein the second space is a space outside the work machine.

9. The work machine according to claim 1 , wherein a width of the first opening in the first direction is smaller than the thickness of the case.

10. a second opening formed in the partition wall and communicating between the first space and the second space, The work machine according to claim 1 , wherein the rib is connected to a portion of the partition wall between the first opening and the second opening.

11. It also has a guide bar, The working unit includes: A sprocket that is rotated by the drive of the motor; The work machine according to claim 1 , further comprising: a saw chain that runs around the periphery of the guide bar as the sprocket rotates.

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