Work machine

Abstract

The invention relates to a working machine, and provides a technology capable of suppressing reduction of torque transmitted from a prime motor to a working part through an output shaft in the working machine. This work machine is provided with: a prime mover having an output shaft; a working part connected to the output shaft; a sliding mechanism; and a fan attached to the output shaft via a slip mechanism, the slip mechanism rotating the output shaft and the fan integrally when a load torque applied to the output shaft when the fan is driven is less than a predetermined value, and the slip mechanism rotating the output shaft and the fan relative to each other when the load torque when the fan is driven is equal to or greater than the predetermined value.

Description

Technical Field

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

[0002] Patent Document 1 discloses a working machine including a prime mover having an output shaft, a working unit connected to the output shaft, and a fan connected to the output shaft.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2002-210705 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] In the working machine of Patent Document 1, the working unit and the fan are driven in response to the prime mover being driven. Depending on the conditions under which the working machine is used, the torque required to drive the fan is sometimes greater than the torque required when the working machine is used in the air (hereinafter referred to as "normal use conditions"). In such a case, the torque transmitted from the prime mover to the working unit via the output shaft is smaller than the torque transmitted under normal use conditions.

[0008] This specification provides a technology capable of suppressing a decrease in torque transmitted from a prime mover to a working unit via an output shaft in a working machine.

[0009] Solutions for solving problems

[0010] The working machine disclosed in this specification may include: a prime mover having an output shaft; a working part connected to the output shaft; a sliding mechanism; and a fan mounted on the output shaft via the sliding mechanism. Alternatively, when the load torque applied to the output shaft when driving the fan is less than a predetermined value, the sliding mechanism causes the output shaft and the fan to rotate integrally, and when the load torque when driving the fan is greater than the predetermined value, the sliding mechanism causes the output shaft and the fan to rotate relative to each other.

[0011] Under normal use conditions, the load torque is less than a predetermined value. On the other hand, under conditions different from normal use conditions, the load torque sometimes becomes greater than a predetermined value. According to the above-mentioned structure, when the load torque when driving the fan is less than a predetermined value, the sliding mechanism causes the output shaft and the fan to rotate integrally. The reason is that when the load torque is less than a predetermined value, the static friction torque generated by the sliding mechanism is greater than the load torque. On the other hand, when the load torque when driving the fan is greater than a predetermined value, the sliding mechanism causes the output shaft and the fan to rotate relative to each other. That is, the sliding mechanism causes the fan to slip relative to the output shaft. The reason is that when the load torque is greater than a predetermined value, the static friction torque generated by the sliding mechanism is less than the load torque. When the output shaft and the fan rotate relative to each other, the torque of the output shaft required to drive the fan is reduced. Therefore, it is possible to suppress the reduction of the torque transmitted from the prime mover to the working unit via the output shaft. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a perspective view of the chain saw 2 according to the embodiment as viewed from the upper left rear side.

[0013] Figure 2 This is a left side view of the chain saw 2 according to the embodiment as seen from the left.

[0014] Figure 3 This is a perspective view of the chain saw 2 according to the embodiment as viewed from the upper right rear side.

[0015] Figure 4 This is a cross-sectional view of the chain saw 2 according to the embodiment as viewed from the right.

[0016] Figure 5 This is a cross-sectional view of the chain saw 2 according to the embodiment as viewed from the front.

[0017] Figure 6 This is a perspective view of the inner housing 66 of the embodiment as viewed from the upper left rear side.

[0018] Figure 7 This is a perspective view of the fan 70 according to the embodiment as viewed from the lower right front.

[0019] Figure 8 yes Figure 5 An enlarged view of the cross-sectional view.

[0020] Fig. 9 This is a cross-sectional view of the chain saw 2 used in the air as viewed from the right.

[0021] Fig.10 This is a cross-sectional view of the chain saw 2 used in water, as viewed from the right.

[0022] Description of Reference Numerals

[0023] 2. Chain saw; 4. Main body; 6. Guide rod; 8. Saw chain; 10. Main body shell; 12. Front hand guard; 14. Front handle; 14a. Left fixing part; 14b. Left grip; 14c. Upper grip; 14d. Right fixing part; 16. Sprocket cover; 18. Battery storage; 20. Rear handle; 22. Rear hand guard; 22a. First protection part; 22b. Second protection part; 24. Left shell; 24a. Exhaust opening; 26. Right shell; 30. Air intake; 30a. Air intake opening; 40. Power button; 42. Trigger rod; 44, locking rod; 50, battery; 52, battery cover; 60, control unit; 62, motor unit; 64, oil tank; 66, inner shell; 68, inner shell cover; 70, fan; 72, sliding mechanism; 74, oil pump; 80, control substrate; 82, substrate support; 84, fin; 90, control unit storage portion; 92, motor unit mounting portion; 94, fan storage portion; 96, first dividing wall; 96a, first opening; 98, first air flow path; 100, second air flow path; 102, second dividing wall; 102a, second opening ; 110, motor housing; 112, waterproof cover; 112a, waterproof member; 114, motor; 120, housing cylindrical portion; 122, reduced diameter portion; 130, cover body; 130a, main body side circular plate portion; 130b, first cylindrical portion; 130c, second cylindrical portion; 130d, main body side opening portion; 132, cover portion; 132a, cover side circular plate portion; 132b, third cylindrical portion; 132c, cover side opening portion; 140, stator; 142, rotor; 144, output shaft; 144a, first groove; 144b, second groove; 150, sprocket ; 152, brake base; 154, brake drum; 160, fan body; 162, bushing; 162a, left cylindrical portion; 162b, right cylindrical portion; 162c, inner circumference; 164, fan disc portion; 164a, central opening; 166, blade portion; 168, cover portion; 168a, fan side air intake opening; 169, rib; 169a, inner circumference; 170, right E-ring; 172, right washer; 174, central washer; 176, coil spring; 178, left washer; 180, left E-ring; A, center axis. DETAILED DESCRIPTION

[0024] Representative and non-limiting specific examples of the present invention are described in detail below with reference to the accompanying drawings. This detailed description is intended to simply show the details of the preferred examples for implementing the present invention to those skilled in the art, and is not intended to limit the scope of the present invention. In addition, in order to provide further improved working machines, their manufacturing methods and methods of use, the additional features and technical solutions disclosed below can be used separately from other features and technical solutions or used together with other features and technical solutions.

[0025] In addition, the combination of features and processes disclosed in the following detailed description is not necessary in the broadest sense when implementing the present invention, and is only recorded for the purpose of specifically illustrating the representative specific examples of the present invention. Furthermore, when providing additional and useful embodiments of the present invention, the various features of the above-mentioned and following representative specific examples and the various features described in the independent claims and dependent claims do not necessarily have to be combined as in the specific examples described herein or in the order in which they are listed.

[0026] All features described in this specification and / or claims are intended to be disclosed separately and independently of the structures of the features described in the embodiments and / or claims as limitations on the disclosure and specific matters claimed in the original application. Furthermore, all numerical ranges and records related to organizations or groups are intended to disclose the above-mentioned intermediate structures as limitations on the disclosure and specific matters claimed in the original application.

[0027] In one or more embodiments, the working machine may include: a prime mover having an output shaft; a working part connected to the output shaft; a sliding mechanism; and a fan mounted on the output shaft via the sliding mechanism. Alternatively, when the load torque applied to the output shaft when driving the fan is less than a predetermined value, the sliding mechanism causes the output shaft and the fan to rotate integrally, and when the load torque when driving the fan is greater than the predetermined value, the sliding mechanism causes the output shaft and the fan to rotate relative to each other.

[0028] In one or more embodiments, it may be that when the fan is driven in a state where the fan is at least partially immersed in water, the load torque is greater than the predetermined value, and when the fan is driven in a state where the fan is not immersed in water at all, the load torque is less than the predetermined value.

[0029] Generally speaking, the resistance of water applied to the fan when the fan is driven in water is greater than the resistance of air applied to the fan when the fan is driven in air. Therefore, the resistance applied to the fan when the fan is driven in a state where the fan is at least partially immersed in water is greater than the resistance applied to the fan when the fan is driven in a state where the fan is not immersed in water at all. Thus, the load torque when the fan is at least partially immersed in water is greater than the load torque when the fan is not immersed in water at all, and is greater than a predetermined value. According to the above-mentioned structure, when the fan is at least partially immersed in water, the sliding mechanism causes the output shaft and the fan to rotate relative to each other. Therefore, when the fan is at least partially immersed in water, the torque transmitted from the prime mover to the working unit via the output shaft can be suppressed from decreasing.

[0030] In one or more embodiments, the sliding mechanism may also have a force applying member extending axially along the output shaft, one end of the force applying member is connected to one of the output shaft and the fan, and the other end of the force applying member abuts against the other of the fan and the output shaft.

[0031] According to the above structure, by adjusting the acting force of the urging member, the static friction torque generated by the acting force can be adjusted. That is, by adjusting the acting force of the urging member, the predetermined value can be adjusted. Therefore, the working machine can cope with various situations.

[0032] In one or more embodiments, the sliding mechanism may further include a washer provided between the other end of the urging member and the fan in the axial direction. The other end of the urging member may abut against the other of the fan and the output shaft via the washer.

[0033] According to the above structure, the washer abuts against the fan instead of the force member. In the case of a structure in which the force member abuts against the fan, the portion of the fan abutting against the force member will wear. By a washer abutting against the fan instead of the force member, the contact area of ​​the portion abutting against the fan can be increased, thereby suppressing fan wear.

[0034] In one or more embodiments, the fan may include: a fan body, which is made of resin and has an opening for the output shaft to pass through; and a bushing, which is made of metal and is provided in the opening. The output shaft may be made of metal. A gap may be provided between the bushing and the output shaft in a direction orthogonal to the axial direction of the output shaft. Surface treatment may be applied to at least one of the inner circumferential surface of the bushing and the portion of the output shaft opposite to the inner circumferential surface.

[0035] When the operating machine is used in water, the metal bushing and the metal output shaft will corrode. In addition, when the bushing and the output shaft are corroded, substances produced by corrosion will be generated. The substances produced by corrosion sometimes cause the gap between the bushing and the output shaft to disappear. In this case, regardless of whether the load torque when driving the fan is above a predetermined value, the output shaft and the fan will rotate as a whole. According to the above-mentioned structure, it is possible to suppress the corrosion of at least one of the parts of the bushing and the output shaft that are opposite to the inner circumferential surface, and the output shaft and the fan can be relatively rotated when the load torque when driving the fan is above a predetermined value.

[0036] In one or more embodiments, the fan may include: a fan body made of resin and having an opening through which the output shaft passes; and a bushing made of metal and disposed in the opening. The sliding mechanism may include a force member extending along the axial direction of the output shaft, one end of the force member being connected to the output shaft, and the other end of the force member being in contact with the bushing of the fan.

[0037] The portion of the fan that contacts the force member of the sliding mechanism will wear. Compared with the resin fan body, the metal bushing is not easy to wear. Therefore, the wear of the portion of the fan that contacts the force member of the sliding mechanism can be suppressed, thereby improving the durability of the fan.

[0038] In one or more embodiments, the prime mover may also be a motor.

[0039] When the prime mover is a motor, when the load torque of the motor is too large, an excessive current (hereinafter referred to as "overcurrent") will flow through the motor. According to the above structure, the overcurrent can be suppressed from flowing through the motor, so that the motor can be protected.

[0040] (Example)

[0041] like Figure 1 As shown in FIG. 1 , the chain saw 2 includes a main body 4, a guide rod 6, and a saw chain 8. The guide rod 6 is a slender plate-shaped member mounted on the main body 4 so as to protrude forward from the main body 4. The guide rod 6 is made of a metal material such as iron. The saw chain 8 includes a plurality of blades connected to each other and is mounted along the periphery of the guide rod 6. In the following description, Figure 2 As shown, when the chain saw 2 is placed on a loading surface S that is horizontal to the ground, the direction perpendicular to the loading surface S is called the up-down direction of the chain saw 2, the direction in which the length direction of the guide rod 6 is projected onto the loading surface S is called the front-back direction of the chain saw 2, and the direction perpendicular to the up-down direction and the front-back direction of the chain saw 2 is called the left-right direction of the chain saw 2.

[0042] The main body 4 includes a main body case 10, a front hand guard 12, a front handle 14, and a sprocket cover 16 (see Figure 3 ), a battery storage portion 18, a rear handle 20 and a rear hand guard 22. Figure 1 As shown, the main body case 10 is composed of a left side case 24 and a right side case 26. The main body case 10 has a substantially rectangular parallelepiped shape having a length direction in the front-rear direction of the main body portion 4.

[0043] An air intake portion 30 having a plurality of air intake openings 30a is provided on the left surface of the left side housing 24. Figure 4 As shown, an exhaust opening 24 a is provided at the front upper portion of the left side housing 24 .

[0044] Figure 1 The front handle 14 is threadedly fixed to the lower surface of the left shell 24, and includes a left fixing portion 14a extending to the left from the lower surface of the left shell 24, a left gripping portion 14b extending upward from the left end of the left fixing portion 14a, an upper gripping portion 14c extending to the right from the upper end of the left gripping portion 14b, and a right fixing portion 14d extending rearward and downward from the right end of the upper gripping portion 14c. Figure 3 As shown, the right fixing portion 14d is screwed to the right housing 26 at a position further back than the sprocket cover 16. The front hand guard 12 is rotatably supported at the front upper portion of the main body housing 10. The front hand guard 12 is provided at a position further forward than the front handle 14. The front hand guard 12 protects the hand of the user who holds the upper grip portion 14c of the front handle 14.

[0045] The rear handle 20 extends from the upper rear surface of the main body housing 10 toward the rear and lower sides, and then bends downward. The rear hand guard 22 extends from the lower rear surface of the main body housing 10 toward the rear, and is connected to the lower end of the rear handle 20. The rear hand guard 22 includes a first protection portion 22a disposed directly below the rear handle 20 and a second protection portion 22b extending to the right from the first protection portion 22a. The rear hand guard 22 protects the hand of the user holding the rear handle 20.

[0046] A power button 40 for the user to switch the power supply of the chain saw 2 on and off is arranged on the upper surface near the front end of the rear handle 20. A trigger lever 42 for the user to operate to rotate the saw chain 8 is arranged on the lower surface near the front end of the rear handle 20. A lock lever 44 is arranged on the upper surface of the rear handle 20 to switch between a state in which the user is allowed to operate the trigger lever 42 and a state in which the user is prohibited from operating the trigger lever 42. The lock lever 44 is arranged at a position behind the power button 40. When the user uses the chain saw 2, the user holds the chain saw 2 by holding the rear handle 20 with the right hand and the front handle 14 with the left hand. When the user presses the lock lever 44 of the rear handle 20 with the palm of the right hand from this state, the state in which the user is allowed to operate the trigger lever 42 is achieved. In this state, the user pulls up the trigger lever 42 with the index finger of the right hand, thereby driving the saw chain 8 to rotate.

[0047] The battery storage section 18 is provided between the front handle 14 and the rear handle 20. The battery storage section 18 stores the battery 50 (see Figure 4 ) The battery storage section 18 includes an openable and closable battery cover 52 .

[0048] like Figure 4As shown, a control unit 60, a motor unit 62, an oil tank 64, an inner housing 66, and an inner housing cover 68 are arranged in the front part of the main housing 10 (see Figure 5 )、Fan 70 (refer to Figure 5 )、sliding mechanism 72 (refer to Figure 5 ) and oil pump 74 (refer to Figure 5 ). The control unit 60 is arranged above the motor unit 62. The control unit 60 includes a control substrate 80 and a substrate support portion 82 that supports the control substrate 80. The substrate support portion 82 is provided with a plurality of fins 84 that protrude downward. The oil tank 64 is provided at the front lower portion of the main body housing 10. The oil tank 64 stores lubricating oil for lubricating the saw chain 8.

[0049] like Figure 5 As shown, the inner housing 66 includes a control unit storage portion 90 for storing the control unit 60, a motor unit mounting portion 92, and a fan storage portion 94 for storing the fan 70. In the vertical direction, a first boundary wall 96 is provided between the control unit storage portion 90 and the motor unit mounting portion 92 and the fan storage portion 94. Figure 4 As shown, a first opening 96a is provided at the rear of the first boundary wall 96 to connect the control unit storage section 90 and the fan storage section 94. A first air flow path 98 for air flow is formed in the fan storage section 94. A second air flow path 100 is formed in the control unit storage section 90 to connect the first air flow path 98 and the exhaust opening 24a of the left housing 24. Figure 5 As shown in FIG. 1 , a second boundary wall 102 is provided between the motor unit mounting portion 92 and the fan housing portion 94. A second opening 102a is provided in the center of the second boundary wall 102. Figure 6 As shown, an inner housing cover 68 is attached to the left portion of the inner housing 66. The outer shape of the inner housing cover 68 has a shape corresponding to the outer shape of the left portion of the inner housing 66.

[0050] like Figure 5 As shown, the motor unit 62 includes a motor housing 110, a waterproof cover 112, and a motor 114. The motor housing 110 is screwed to the right surface of the second boundary wall 102 of the inner housing 66. The motor housing 110 includes a housing cylindrical portion 120 and a reduced diameter portion 122 extending to the left from the left end of the housing cylindrical portion 120. The axis of the housing cylindrical portion 120 coincides with the central axis A of the output shaft 144 described later. The inner diameter of the left end of the reduced diameter portion 122 is smaller than the diameter of the second opening 102a of the second boundary wall 102.

[0051] The waterproof cover 112 includes a cover body 130 and a cover 132. The cover body 130 includes a main body side circular plate portion 130a, a first cylindrical portion 130b having a cylindrical shape, and a second cylindrical portion 130c having a cylindrical shape. The axes of the main body side circular plate portion 130a, the first cylindrical portion 130b, and the second cylindrical portion 130c are consistent with the central axis A of the output shaft 144 described later. A main body side opening portion 130d is provided in the central portion of the main body side circular plate portion 130a. The first cylindrical portion 130b extends to the right from the radially outer end of the main body side circular plate portion 130a. The outer diameter of the first cylindrical portion 130b is smaller than the inner diameter of the outer shell cylindrical portion 120 of the motor housing 110. Therefore, a gap is provided between the first cylindrical portion 130b and the outer shell cylindrical portion 120 of the motor housing 110. The second cylindrical portion 130c extends to the left from the main body side circular plate portion 130a at the periphery of the main body side opening portion 130d. The cover portion 132 includes a cover side circular plate portion 132a and a third cylindrical portion 132b. A cover side opening portion 132c is provided at the central portion of the cover side circular plate portion 132a. The third cylindrical portion 132b extends to the left from the cover side circular plate portion 132a at the periphery of the cover side opening portion 132c. The cover portion 132 covers the opening at the right end portion of the cover main body portion 130.

[0052] The motor 114 is waterproofed by the waterproof cover 112. The motor 114 is an inner rotor type DC brushless motor. In addition, in a modified example, the motor 114 may also be an outer rotor type brushless motor or a brushed motor. The motor 114 includes a stator 140, a rotor 142 arranged inside the stator 140, and an output shaft 144 arranged in a manner penetrating the center of the stator 140 and the rotor 142 and fitted to the rotor 142. The output shaft 144 extends along the central axis A. The central axis A is parallel to the left-right direction. The direction along the central axis A will be described as "axial direction" hereinafter. The left end of the output shaft 144 is located to the left of the left end of the waterproof cover 112, and the right end of the output shaft 144 is located to the right of the right end of the waterproof cover 112. That is, the output shaft 144 penetrates the waterproof cover 112 in the left-right direction. In the waterproof cover 112, a plurality of waterproof members 112a are provided at the portion through which the output shaft 144 penetrates.

[0053] A sprocket 150 and a brake base 152 are fixed to the right end of the output shaft 144. Figure 1 ) is mounted on the sprocket 150 from the guide rod 6. A brake drum 154 is fitted into the brake base 152. When the motor 114 is driven, the sprocket 150 rotates together with the output shaft 144, thereby rotating the saw chain 8 around the sprocket 150 and the guide rod 6.

[0054] A fan 70, a sliding mechanism 72 and an oil pump 74 are mounted on the left end of the output shaft 144. Figure 7As shown in FIG. 1 , the fan 70 includes a resin fan body 160, a metal bushing 162, and ribs 169. As an example, the bushing 162 is made of stainless steel. The fan body 160 includes a fan disk 164, a plurality of blades 166, and a cover 168. Figure 8 As shown, a central opening 164a is provided in the central portion of the fan disc portion 164. Ribs 169 are connected to the fan disc portion 164 and extend to the right from the portion of the fan disc portion 164 located at the periphery of the central opening 164a. The inner diameter of the ribs 169 is smaller than the diameter of the central opening 164a. The outer diameter of the ribs 169 is smaller than the outer diameter of the fan disc portion 164.

[0055] The bushing 162 is mounted on the inner circumference of the central opening 164a and the rib 169. The bushing 162 includes a left cylindrical portion 162a and a right cylindrical portion 162b. The left cylindrical portion 162a and the right cylindrical portion 162b are mounted on the inner circumference of the central opening 164a and the inner circumference 169a of the rib 169, respectively. An insulating surface treatment (e.g., coating treatment) is applied to the inner circumference 162c of the bushing 162 to prevent corrosion when the bushing 162 comes into contact with water. In addition, an insulating surface treatment is also applied to the portion of the output shaft 144 that faces the inner circumference 162c. The inner diameter of the bushing 162 is slightly larger than the outer diameter of the portion of the output shaft 144 that faces the bushing 162. That is, a gap C is provided between the bushing 162 and the output shaft 144.

[0056] like Figure 7 As shown, the fan disc portion 164 and the plurality of blade portions 166 are integrally formed. The plurality of blade portions 166 extend to the right from the fan disc portion 164. When the fan 70 is viewed from the right, the plurality of blade portions 166 bend in the counterclockwise direction as they move from the radial inside to the outside. The cover portion 168 is welded to the right end of the plurality of blade portions 166. A fan side air intake opening portion 168a is provided in the central portion of the cover portion 168. The diameter of the fan side air intake opening portion 168a is larger than the outer diameter of the rib 169.

[0057] like Figure 8 As shown in the figure, a first groove 144a is formed along the circumferential direction at a position on the right side of the bushing 162 of the output shaft 144, and a second groove 144b is formed at a position on the left side of the bushing 162 of the output shaft 144. A right E-shaped ring 170 is embedded in the first groove 144a. A right washer 172 is provided between the right E-shaped ring 170 and the bushing 162. The right washer 172 abuts against the right E-shaped ring 170 and the bushing 162.

[0058] The sliding mechanism 72 is provided on the left side of the fan 70. The sliding mechanism 72 includes a central washer 174, a coil spring 176, a left washer 178, and a left E-shaped ring 180. The left E-shaped ring 180 is embedded in the second groove 144b of the output shaft 144. The central washer 174 is arranged at a position where its right surface abuts against the bushing 162. The left washer 178 is arranged at a position where its left surface abuts against the left E-shaped ring 180. The coil spring 176 is arranged between the central washer 174 and the left washer 178. The central washer 174 is pressed against the bushing 162 by the urging force of the coil spring 176. The force of the coil spring 176 is adjusted in the following manner: when the torque loaded on the output shaft 144 when driving the fan 70 (hereinafter referred to as "load torque") is less than a predetermined value, the fan 70 and the output shaft 144 rotate integrally; when the load torque when driving the fan 70 is greater than a predetermined value, the fan 70 and the output shaft 144 rotate relative to each other.

[0059] In addition, the state in which the load torque when driving the fan 70 is less than the predetermined value means a state in which the static friction torque generated by the sliding mechanism 72 is greater than the load torque. In this case, the fan 70 rotates integrally with the output shaft 144 in accordance with the connection between the fan 70 and the output shaft 144 via the sliding mechanism 72. In addition, the state in which the fan 70 rotates integrally with the output shaft 144 means a state in which the rotation speed of the fan 70 is substantially the same as the rotation speed of the output shaft 144.

[0060] In addition, the state in which the load torque when driving the fan 70 is greater than a predetermined value refers to a state in which the load torque exceeds the static friction torque generated by the sliding mechanism 72. In this case, the fan 70 and the output shaft 144 rotate relatively to each other in accordance with the sliding of the fan 70 and the output shaft 144 by the sliding mechanism 72. Specifically, the fan 70 rotates under the action of the dynamic friction torque generated by the sliding mechanism 72. In addition, the state in which the fan 70 and the output shaft 144 rotate relatively to each other refers to a state in which the rotation speed of the fan 70 is less than the rotation speed of the output shaft 144.

[0061] (Chainsaw 2 action in the air)

[0062] Next, the operation of the chain saw 2 when the chain saw 2 is used in the air will be described.

[0063] When the user presses Figure 1 When the locking lever 44 of the rear handle 20 is pulled up and the trigger lever 42 is pulled up, Figure 5 The motor 114 starts to drive, and the output shaft 144 rotates. As a result, the sprocket 150 connected to the output shaft 144 of the motor 114 rotates. Fig. 9As shown, when the chain saw 2 is used in the air, the load torque becomes a torque T1 that is smaller than the predetermined value. This is because the air resistance applied to the fan 70 when the fan 70 is driven is small. In this case, the fan 70 is connected to the output shaft 144 via the sliding mechanism 72, and the output shaft 144 and the fan 70 rotate integrally. That is, the output shaft 144 and the fan 70 rotate integrally in response to the motor 114 being driven.

[0064] By driving the fan 70, air outside the main body housing 10 passes through the air intake opening 30a (see FIG. 1 ) of the left side housing 24. Figure 1 ) and is sucked into the interior of the main body casing 10. The air flowing into the interior of the main body casing 10 passes through the inner casing 66 (see Figure 6 ) around, then, as Figure 5 As shown, the air passes between the waterproof cover 112 and the motor housing 110 in the left direction. The air passes between the waterproof cover 112 and the motor housing 110, thereby cooling the motor 114. Furthermore, the air passes through the second opening 102a of the second boundary wall 102 and is sucked into the fan 70. As described above, the shape of the plurality of blades 166 of the fan 70 is bent in the counterclockwise direction from the radial inside to the outside (refer to Figure 7 Therefore, the air sucked by the fan 70 is pushed outward in the radial direction toward the first air flow path 98 (see Figure 4 ) flows in. Then, Figure 4 As shown, the air flowing into the first air flow path 98 passes through the first opening 96a and the second air flow path 100. The air passes through the second air flow path 100, thereby cooling the control board 80. Then, the air in the second air flow path 100 is discharged to the outside from the exhaust opening 24a of the left case 24.

[0065] (Chainsaw 2 in water)

[0066] Next, the operation of the chain saw 2 when the chain saw 2 is used in water will be described. The user performs the same operation as when the chain saw 2 is used in air, thereby Figure 5 The motor 114 starts to drive, and the output shaft 144 rotates. Fig.10As shown, when the chain saw 2 is used in water, the load torque becomes a torque T2 greater than a predetermined value. The reason for this is that the resistance of water applied to the fan 70 when the fan 70 is driven in water is greater than the resistance of air applied to the fan 70 when the fan 70 is driven in air. In this case, the resistance of water applied to the fan 70 exceeds the force of the coil spring 176, and the central washer 174 of the sliding mechanism 72 and the bushing 162 of the fan 70 slide. As a result, the rotation speed of the fan 70 is lower than the rotation speed of the output shaft 144, and the output shaft 144 and the fan 70 rotate relatively. Specifically, the rotation speed of the fan 70 is lower than the rotation speed of the output shaft 144.

[0067] As described above, in the chain saw 2 of the present embodiment, when the chain saw 2 is used in air, the output shaft 144 and the fan 70 rotate integrally, and when the chain saw 2 is used in water, the output shaft 144 and the fan 70 rotate relatively.

[0068] In one or more embodiments, the chain saw 2 (an example of a "working machine") includes: a motor 114 (an example of a "prime mover") having an output shaft 144; a saw chain 8 (an example of a "working unit") connected to the output shaft 144; a sliding mechanism 72; and a fan 70 mounted on the output shaft 144 via the sliding mechanism 72. When the load torque when the fan 70 is driven is less than a predetermined value, the sliding mechanism 72 causes the output shaft 144 and the fan 70 to rotate integrally, and when the load torque when the fan 70 is driven is greater than a predetermined value, the sliding mechanism 72 causes the output shaft 144 and the fan 70 to rotate relatively.

[0069] When the chain saw 2 is used in air, the load torque is less than a predetermined value. On the other hand, when the chain saw 2 is used in water, the load torque is greater than a predetermined value. According to the above structure, when the load torque when driving the fan 70 is less than a predetermined value, the sliding mechanism 72 rotates the output shaft 144 and the fan 70 integrally. The reason is that when the load torque is less than a predetermined value, the static friction torque generated by the sliding mechanism 72 is greater than the load torque. On the other hand, when the load torque when driving the fan 70 is greater than a predetermined value, the sliding mechanism 72 rotates the output shaft 144 and the fan 70 relatively. That is, the sliding mechanism 72 causes the fan 70 to slip relative to the output shaft 144. The reason is that when the load torque is greater than a predetermined value, the static friction torque generated by the sliding mechanism 72 is less than the load torque. When the output shaft 144 and the fan 70 rotate relatively, the torque of the output shaft 144 required to drive the fan 70 is reduced. Therefore, it is possible to suppress the reduction of the torque transmitted from the motor 114 to the saw chain 8 via the output shaft 144.

[0070] In one or more embodiments, when the fan 70 is at least partially immersed in water, the load torque is greater than a predetermined value, and when the fan 70 is not immersed in water at all, the load torque is less than the predetermined value.

[0071] Generally, the resistance of water applied to the fan 70 when the fan 70 is driven in water is greater than the resistance of air applied to the fan 70 when the fan 70 is driven in air. Therefore, the resistance applied to the fan 70 when the fan 70 is driven in a state where at least a portion of the fan 70 is immersed in water is greater than the resistance applied to the fan 70 when the fan 70 is driven in a state where the fan 70 is not immersed in water at all. Thus, the load torque when the fan 70 is at least partially immersed in water is greater than the load torque when the fan 70 is not immersed in water at all, and is greater than a predetermined value. According to the above-mentioned structure, when the fan 70 is at least partially immersed in water, the slide mechanism 72 rotates the output shaft 144 relative to the fan 70. Therefore, when the fan 70 is at least partially immersed in water, it is possible to suppress the reduction of the torque transmitted from the motor 114 to the saw chain 8 via the output shaft 144.

[0072] In one or more embodiments, the sliding mechanism 72 has a coil spring 176 (an example of a “force-applying member”) extending axially along the output shaft 144, the left end (an example of “one end”) of the coil spring 176 is connected to the output shaft 144, and the right end (an example of “the other end”) of the coil spring 176 abuts against the fan 70.

[0073] According to the above configuration, the static friction torque generated by the biasing force can be adjusted by adjusting the biasing force of the coil spring 176. That is, the predetermined value can be adjusted by adjusting the biasing force of the coil spring 176. Therefore, the chain saw 2 can cope with various situations.

[0074] In one or more embodiments, the slide mechanism 72 further includes a central washer 174 (an example of a “washer”) provided axially between the right end of the coil spring 176 and the fan 70 . The right end of the coil spring 176 abuts against the fan 70 via the central washer 174 .

[0075] According to the above structure, the central washer 174 abuts against the fan 70 instead of the coil spring 176. The portion of the slide mechanism 72 that abuts against the fan 70 wears. Since the central washer 174 abuts against the fan 70 instead of the coil spring 176, the contact area of ​​the portion that abuts against the fan 70 can be increased, so the wear of the fan 70 can be suppressed.

[0076] In one or more embodiments, the fan 70 includes: a fan body 160, which is made of resin and has a central opening 164a and a rib 169 (an example of an "opening") through which the output shaft 144 passes; and a bushing 162, which is made of metal and is provided at the central opening 164a and the rib 169. The output shaft 144 is made of metal. A gap C is provided between the bushing 162 and the output shaft 144 in a direction orthogonal to the axial direction. The inner circumferential surface 162c of the bushing 162 and a portion of the output shaft 144 that is opposite to the inner circumferential surface 162c are subjected to surface treatment.

[0077] When the chain saw 2 is used in water, the metal bushing 162 and the metal output shaft 144 may corrode. In addition, when the bushing 162 and the output shaft 144 corrode, substances generated by the corrosion are generated. The substances generated by the corrosion sometimes cause the gap C between the bushing 162 and the output shaft 144 to disappear. In this case, regardless of whether the load torque when driving the fan 70 is greater than a predetermined value, the output shaft 144 and the fan 70 rotate integrally. According to the above-mentioned structure, it is possible to suppress the corrosion of at least one of the bushing 162 and the output shaft 144, and it is possible to make the output shaft 144 and the fan 70 rotate relative to each other when the load torque when driving the fan 70 is greater than a predetermined value.

[0078] In one or more embodiments, the fan 70 includes: a fan body 160 made of resin, having a central opening 164a through which the output shaft 144 passes, and ribs 169; and a bushing 162 made of metal and provided at the central opening 164a and the ribs 169. The sliding mechanism 72 includes a coil spring 176 extending in the axial direction, the left end of the coil spring 176 is connected to the output shaft 144, and the right end of the coil spring 176 abuts against the bushing 162 of the fan 70.

[0079] The portion of the fan 70 that contacts the coil spring 176 of the sliding mechanism 72 is subject to wear. The metal bushing 162 is less susceptible to wear than the resin fan body 160. Therefore, the wear of the portion of the fan 70 that contacts the coil spring 176 of the sliding mechanism 72 can be suppressed, thereby improving the durability of the fan 70.

[0080] In one or more embodiments, the chain saw 2 includes a motor 114 as a prime mover.

[0081] When the prime mover is the motor 114, when the load torque of the output shaft 144 of the motor 114 is too large, an excessive current (hereinafter referred to as "overcurrent") flows through the motor 114. According to the above structure, the overcurrent can be suppressed from flowing through the motor 114. Therefore, the motor 114 can be protected.

[0082] (First Modification) The "working machine" is not limited to the chain saw 2, and may be a lawn mower, a lawn mower, a hedge trimmer, or the like.

[0083] (Second modification) The right end of the coil spring 176 of the sliding mechanism 72 may be connected to the fan 70, and the left end may abut against the output shaft 144. In this modification, the right end and the left end of the coil spring 176 are examples of "one end" and "the other end" of the "urging member", respectively.

[0084] (Third Modification) The slide mechanism 72 may include an elastic member such as a disc spring or rubber instead of the coil spring 176. In another modification, the slide mechanism 72 may not include the center washer 174.

[0085] (Fourth Modification) The fan 70 may not include the bushing 162. In another modification, the inner circumferential surface 162c of the bushing 162 and the portion of the output shaft 144 facing the inner circumferential surface 162c may not be subjected to surface treatment. In yet another modification, only one of the inner circumferential surface 162c of the bushing 162 and the portion of the output shaft 144 facing the inner circumferential surface 162c may be subjected to surface treatment.

[0086] (Fifth Modification) The slide mechanism 72 may be in contact with the resin fan body 160 in the fan 70 .

[0087] (Sixth Modification) The "prime mover" is not limited to the motor 114, and may be an engine or the like.

[0088] (Seventh Modification) In the above-mentioned chain saw 2, the saw chain 8 is provided on the right side of the motor 114 in the axial direction, and the sliding mechanism 72 and the fan 70 are provided in sequence on the left side of the motor 114. In a modification, the saw chain 8, the fan 70, and the sliding mechanism 72 may be provided on the left or right side of the motor 114 in the axial direction.

Claims

1. A working machine, wherein: The operating machine has: a prime mover having an output shaft; A working part connected to the output shaft; Sliding mechanism; and a fan, which is mounted on the output shaft via the sliding mechanism, When the load torque applied to the output shaft when the fan is driven is less than a predetermined value, the sliding mechanism causes the output shaft and the fan to rotate integrally. The slide mechanism causes the output shaft and the fan to rotate relative to each other when the load torque when the fan is driven is equal to or greater than the predetermined value.

2. The working machine according to claim 1, wherein: When the fan is driven in a state where at least a part of the fan is immersed in water, the load torque is equal to or greater than the predetermined value. When the fan is driven in a state where the fan is not immersed in water at all, the load torque is smaller than the predetermined value.

3. The working machine according to claim 1 or 2, wherein: The sliding mechanism includes a biasing member extending in the axial direction of the output shaft. One end of the force applying member is connected to one of the output shaft and the fan. The other end of the urging member abuts against the other of the fan and the output shaft.

4. The working machine according to claim 3, wherein: The sliding mechanism further includes a washer provided between the other end of the urging member and the fan in the axial direction. The other end of the urging member abuts against the other of the fan and the output shaft via the washer.

5. The working machine according to any one of claims 1 to 4, wherein: The fan has: a fan body made of resin and having an opening through which the output shaft passes; and a bushing made of metal and provided at the opening; The output shaft is made of metal. A gap is provided between the bushing and the output shaft in a direction orthogonal to the axial direction of the output shaft. A surface treatment is performed on at least one of an inner peripheral surface of the bush and a portion of the output shaft facing the inner peripheral surface.

6. The working machine according to any one of claims 1 to 5, wherein: The fan has: a fan main body made of resin and having an opening through which the output shaft passes; as well as a bushing made of metal and provided at the opening; The sliding mechanism includes a biasing member extending in the axial direction of the output shaft, one end of the biasing member is connected to the output shaft, and the other end of the biasing member abuts against the bushing of the fan.

7. The working machine according to any one of claims 1 to 6, wherein: The prime mover is a motor.

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