Chainsaw

Abstract

To provide a cain saw having a chain saw tensioning mechanism capable of preventing damaging of a resin adjustment dial.SOLUTION: A chain saw 1 has a chain tensioning mechanism 50. The chain tensioning mechanism 50 comprises: a resin adjustment dial 60 freely rotatable around a lateral axis; a metallic rotation transmission member 70 freely rotatable around the lateral axis; a metallic feed screw member 80 freely rotatable around an axis in the longitudinal direction; and a sliding member 90 connected to a guide bar 20. The sliding member 90 is threadedly engaged with the feed screw member 80. A first gear 65 of the adjustment dial 60 and a second gear 71 of the rotation transmission member 70 are meshed together, and a first bevel gear 72 of the rotation transmission member 70 and a second bevel gear 82 of the feed screw member 80 are meshed together.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a chainsaw provided with a chain tensioning mechanism for adjusting the tension of a saw chain.

Background Art

[0002] A chainsaw used for cutting trees, lumber, etc. is provided with a chain tensioning mechanism for adjusting the tension of a saw chain wound around the outer peripheral portion of a guide bar. As a chain tensioning mechanism, there is one that includes an adjustment dial provided on the outer surface of the chainsaw body and a feed screw member provided inside the chainsaw body, and the adjustment dial and the feed screw member are connected by a bevel gear mechanism (see, for example, Patent Document 1).

[0003] In such a chain tensioning mechanism, a slide member is screwed into a screw groove of the feed screw member, and the slide member is connected to the guide bar. Then, when the adjustment dial is rotated, the guide bar moves in the extending direction together with the slide member as the feed screw member rotates, so that the tension of the saw chain changes.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the above-described conventional chain tensioning mechanism, a bevel gear of a resin-made adjustment dial and a bevel gear of a metal-made feed screw member are meshed with each other. In this configuration, there is a problem that the tooth portion of the resin-made bevel gear is easily damaged by the tooth portion of the metal-made bevel gear.

[0006] The present invention aims to solve the above-described problems and provides a chain saw having a chain tensioning mechanism that can easily adjust the tension of the saw chain and prevent damage to the resin adjustment dial.

Means for Solving the Problems

[0007] To solve the above problems, the present invention provides a chain saw having a chain saw body and a guide bar extending in the front-rear direction, with the rear portion of the guide bar connected to the chain saw body. The chain saw is provided with a chain tensioning mechanism for adjusting the tension of the saw chain wound around the outer peripheral portion of the guide bar. The chain tensioning mechanism includes a resin adjustment dial rotatable around an axis in the left-right direction on the outer surface of the chain saw body, a metal rotary transmission member rotatable around an axis in the left-right direction, a metal feed screw member rotatable around an axis in the front-rear direction inside the chain saw body, and a slide member connected to the guide bar. The slide member is screwed onto the feed screw member and moves in the front-rear direction as the feed screw member rotates. A first gear formed on the adjustment dial meshes with a second gear formed on the outer peripheral portion of the rotary transmission member, and a first bevel gear formed on the rotary transmission member meshes with a second bevel gear formed on the feed screw member. Cylindrical-shaped In the chain saw of the present invention, when the adjustment dial is rotated, the rotational force is transmitted to the feed screw member via the rotary transmission member, and as the feed screw member rotates, the slide member is fed in the extending direction of the guide bar. Then, as the guide bar moves in the extending direction together with the slide member, the tension of the saw chain changes. Outer peripheral surface The adjustment dial and the first gear are a single component.

[0008]

[0009] ​​In the chainsaw of the present invention, the first gear provided on the adjustment dial and the second gear provided on the rotation transmission member rotate around an axis extending in the left-right direction. When engaging two gears that rotate around two axes in the same direction, the module of the tooth portion of the gear can be increased to enhance the strength of the tooth portion. And by enhancing the strength of the first gear, it is possible to prevent the resin-made first gear from being damaged by the metal-made second gear.

[0010] Also, in the chainsaw of the present invention, when operating the chain tensioning mechanism, there is an advantage that the outer peripheral portion of the adjustment dial can be gripped and it is easy to apply a rotational force. Furthermore, since the amount of movement of the guide bar is large with respect to the amount of rotation of the adjustment dial, the guide bar can be surely moved with a small force. Also, in the chainsaw of the present invention, since the adjustment dial rotates around an axis extending in the lateral width direction (left-right direction) of the chainsaw body, even if the outer diameter of the adjustment dial is increased, an increase in the lateral width of the chainsaw body can be suppressed. Also, in the chainsaw of the present invention, since the adjustment dial is made of resin, even if the outer diameter of the adjustment dial is increased, an increase in the weight of the chain tensioning mechanism can be suppressed.

Effects of the Invention

[0011] In the chainsaw of the present invention, the structure of the chain tensioning mechanism is simplified by using a gear mechanism, and by rotating the adjustment dial, a rotational force is transmitted from the resin-made adjustment dial to the metal-made feed screw member to adjust the tension of the saw chain.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0013] Embodiments of the present invention will be described in detail with appropriate reference to the drawings. As shown in FIG. 1, the chainsaw 1 of the present embodiment includes a chainsaw body 10, a guide bar 20 connected to the chainsaw body 10, and a chain tensioning mechanism 50 for adjusting the tension of a saw chain 30 wound around the outer peripheral portion of the guide bar 20.

[0014] Since the chainsaw 1 of the present embodiment has the same configuration as a conventionally known chainsaw except for the configuration of the chain tensioning mechanism 50, a detailed description of the overall configuration of the chainsaw 1 will be omitted. In the following description, the front refers to the tip side (the right side in FIG. 1) of the guide bar 20.

[0015] The chainsaw body 10 includes a driving device (not shown) for rotationally driving the saw chain 30, and the driving device is housed in a cover 11.

[0016] The guide bar 20 is a plate-like member extending in the front-rear direction. As shown in FIG. 4, a slide groove 21 extending in the front-rear direction penetrates the rear portion of the guide bar 20. By attaching a bolt (not shown) inserted into this slide groove 21 to the chainsaw body 10 (see FIG. 1), the guide bar 20 is movably connected to the chainsaw body 10 in the front-rear direction.

[0017] The saw chain 30 is an annular cutting member wound around the outer peripheral portion of the guide bar 20. The rear portion of the saw chain 30 is looped around a sprocket of a driving device (not shown), and the saw chain 30 is rotationally driven along the outer periphery of the guide bar 20 by the driving force of the driving device.

[0018] As shown in FIG. 2, the chain tensioning mechanism 50 includes an adjustment dial 60, a rotation transmission member 70, a feed screw member 80, and a slide member 90.

[0019] As shown in FIG. 1, the adjustment dial 60 is a resin-made cylindrical member attached to the right side surface of the cover 11 of the chainsaw body 10. The adjustment dial 60 is rotatably accommodated in the right side surface of the cover 11 about an axis extending in the left-right direction (the width direction of the chainsaw body 10).

[0020] As shown in FIG. 3, on the outer peripheral surface of the adjustment dial 60, ribs 64 extending in the circumferential direction project over the entire circumference. On the outer peripheral surface of the adjustment dial 60, a first gear 65 is formed at a portion on the base end side (the outer surface side of the cover 11) of the rib 64. The first gear 65 is a cylindrical spur gear having tooth portions formed on the outer peripheral surface of the cylindrical member 62.

[0021] In this configuration, the rib 64 disposed substantially at the center of the outer peripheral surface of the adjustment dial 60 prevents chips and dust generated during the operation of the chainsaw 1 from entering the gear portion inside the cover 11, and damage to the gear portion can be avoided. Further, since the adjustment dial 60 and the first gear 65 are single parts and the force when turning the adjustment dial 60 directly becomes the force for turning the first gear 65, when the operator adjusts the tension of the saw chain 30, it is possible to prevent excessive force from being applied to the adjustment dial 60, and damage to the adjustment dial 60 and the first gear 65 can be prevented.

[0022] On the outer peripheral surface of the adjustment dial 60, a grip portion 66 is formed at a portion on the tip side of the rib 64. The grip portion 66 is a portion to be gripped by hand when rotating the adjustment dial 60. Wavy irregularities are continuously formed on the outer peripheral surface of the grip portion 66, making it difficult to slip when a fingertip is placed on the outer peripheral surface of the grip portion 66.

[0023] As shown in Fig. 2, the rotation transmission member 70 is a metal member attached to the left side of the cover 11 of the chainsaw body 10. The rotation transmission member 70 is disposed behind the adjustment dial 60.

[0024] The rotation transmission member 70 is inserted into a hole formed in the cover 11 and is accommodated in the inner surface of the cover 11 in a rotatable state about an axis extending in the left - right direction. The base end portion of the rotation transmission member 70 is disposed on the inner surface side of the cover 11 (see Fig. 3), and the tip end portion of the rotation transmission member 70 is disposed on the outer surface side of the cover 11.

[0025] As shown in Fig. 3, a second gear 71 is formed at the tip end portion of the rotation transmission member 70. The second gear 71 is a spur gear having teeth formed on the outer peripheral surface of the tip end portion of the rotation transmission member 70. A part of the second gear 71 is exposed to the adjustment dial 60 side from an opening formed in the outer surface of the cover 11. And the second gear 71 is meshed with the first gear 65 of the adjustment dial 60 (see Fig. 1).

[0026] In this way, the first gear 65 and the second gear 71 are spur gears and are arranged in parallel inside the cover 11. In this configuration, it is difficult for a large force other than the rotational direction to be applied from the first gear 65 with a large outer diameter to the second gear 71 with a small outer diameter, so damage to the first gear 65 and the second gear 71 can be prevented. Also, by arranging the first gear 65 and the second gear 71 in parallel inside the cover 11, it is not necessary to increase the width of the chainsaw body 10 in the left - right direction, and the chainsaw body 10 can be configured compactly.

[0027] In the chain tensioning mechanism 50 of the present embodiment, the maximum outer diameter of the first gear 65 is formed larger than the maximum outer diameter of the second gear 71. Also, the gear ratio of the second gear 71 to the first gear 65 is set between 0.1 and 0.5. Also, the module of the first gear 65 and the second gear 71 is set to 0.5 mm or more. Increasing the maximum outer diameter of the first gear 65 allows for a larger module to be set for the tooth portion of the first gear 65, reducing damage to the tooth portion molded from resin. However, if the first gear 65 is made too large relative to the second gear 71, there will be insufficient pitch and module for the first gear 65 on the second gear 71 side. On the other hand, if the outer diameter of the first gear 65 is set relatively small, the load on the first gear 65 and the second gear 71 is reduced, but the number of rotations of the adjustment dial 60 increases when adjusting the tension of the chain 30, making the operation of the adjustment dial 60 cumbersome. For this reason, it is desirable that the ratio of the maximum outer diameter of the first gear 65 to the maximum outer diameter of the second gear 71 be in the range of 2:1 to 8:1. Furthermore, it is more desirable to set the ratio of the maximum outer diameter of the first gear 65 to the maximum outer diameter of the second gear 71 in the range of 4:1 to 5:1.

[0028] In the chain tensioning mechanism 50 of the present embodiment, the maximum outer diameter of the adjustment dial 60 formed with the first gear 65 is formed significantly larger than the maximum outer diameter of the second gear 71. With this configuration, by increasing the outer diameter of the adjustment dial 60, the number of rotations of the adjustment dial 60 can be reduced when adjusting the tension of the chain 30, improving the operability of the adjustment dial 60. In the present embodiment, the ratio of the maximum outer diameter of the adjustment dial 60 to the maximum outer diameter of the second gear 71 is set to 4.5:1. With this configuration, the adjustment dial 60 is formed relatively large, and while maintaining the operability of the adjustment dial 60, even when the first gear 65 and the second gear 71, which are spur gears, are arranged side by side in the front-rear direction, the overall gear structure does not become too large, and the chainsaw body 10 can be configured compactly in the front-rear direction.

[0029] A first bevel gear 72 is formed at the base end portion of the rotation transmission member 70. The first bevel gear 72 has a reduced diameter toward the base end side of the rotation transmission member 70.

[0030] The feed screw member 80 is a metal member with a circular cross-section extending in the front-rear direction. The feed screw member 80 is connected to the inner surface of the left side portion of the cover 11 in a rotatable state about an axis extending in the front-rear direction (see Fig. 2). A spiral thread groove 81 is formed on the outer peripheral surface of the feed screw member 80. A second bevel gear 82 is formed at the rear end portion of the feed screw member 80. As can be clearly seen with reference to Figs. 2 and 4, the second bevel gear 82 has a reduced diameter toward the rear end side.

[0031] The slide member 90 is a metal nut screwed into the thread groove 81 of the feed screw member 80 (see Fig. 3). When the feed screw member 80 rotates, the slide member 90 is fed in the front-rear direction by the thread groove 81. In this way, the slide member 90 moves in the front-rear direction as the feed screw member 80 rotates.

[0032] A connecting pin 91 protruding toward the inside of the chainsaw body 10 is formed on the slide member 90. As shown in Fig. 4, the connecting pin 91 is inserted into a connecting hole 25 formed at the rear portion of the guide bar 20. In this way, the slide member 90 is connected to the rear portion of the guide bar 20.

[0033] Next, a method for adjusting the tension of the saw chain 30 shown in Fig. 1 by the chain tensioning mechanism 50 of the present embodiment will be described. When the adjustment dial 60 of the chain tensioning mechanism 50 is rotated, the rotational force is transmitted from the first gear 65 of the adjustment dial 60 to the second gear 71 of the rotation transmission member 70 shown in Fig. 2, and the rotation transmission member 70 rotates about an axis in the left-right direction. Also, the rotational force is transmitted from the first bevel gear 72 of the rotation transmission member 70 to the second bevel gear 82 of the feed screw member 80, and the feed screw member 80 rotates about an axis in the front-rear direction.

[0034] When the feed screw member 80 rotates, the slide member 90 is fed in the front-rear direction by the screw groove 81, and together with the slide member 90, the guide bar 20 (see FIG. 4) moves in the extension direction (front-rear direction). As a result, the tension of the chain 30 changes.

[0035] In the chainsaw 1 of the present embodiment as described above, as shown in FIG. 2, the first gear 65 provided on the adjustment dial 60 of the chain tensioning mechanism 50 and the second gear 71 provided on the rotation transmission member 70 rotate about an axis extending in the left-right direction. Here, when meshing two gears that rotate about two axes in the same direction, the module of the tooth portion of the gear can be increased to enhance the strength of the tooth portion. Therefore, in the chain tensioning mechanism 50 of the present embodiment, by increasing the strength of the first gear 65, it is possible to prevent the resin-made first gear 65 from being damaged by the metal-made second gear 71.

[0036] The chain tensioning mechanism 50 of the present embodiment has a simplified structure by a gear mechanism, and the tension of the chain 30 can be easily adjusted by rotating the adjustment dial 60 without using tools.

[0037] In the chain tensioning mechanism 50 of the present embodiment, the gear ratio of the second gear 71 of the rotation transmission member 70 to the first gear 65 of the adjustment dial 60 is set between 0.1 and 0.5, and the maximum outer diameter of the first gear 65 is formed larger than the maximum outer diameter of the second gear 71. And in accordance with the outer diameter of the first gear 65, the outer diameter of the adjustment dial 60 is also formed large. In this way, when the outer diameter of the adjustment dial 60 is increased, it becomes easier to grip the adjustment dial 60 and apply a rotational force, and since the movement amount of the guide bar 20 becomes larger with respect to the rotation amount of the adjustment dial 60, the guide bar 20 can be moved with less force.

[0038] In the chain tensioning mechanism 50 of this embodiment, as shown in FIG. 1, since the adjustment dial 60 rotates around the axis in the lateral width direction (left - right direction) of the chainsaw body 10, even if the outer diameter of the adjustment dial 60 is increased, it is possible to suppress an increase in the lateral width of the chainsaw body 10.

[0039] Also, in the chain tensioning mechanism 50 of this embodiment, since the adjustment dial 60 is made of resin, even if the outer diameter of the adjustment dial 60 is increased, it is possible to suppress an increase in the weight of the chain tensioning mechanism 50.

[0040] In the chain tensioning mechanism 50 of this embodiment, as shown in FIG. 3, ribs 64 are formed on the outer peripheral surface of the adjustment dial 60, and the first gear 65 is formed at a portion closer to the base end side than the ribs 64. With this configuration, the ribs 64 can prevent dust from entering from the outside of the chainsaw body 10 toward the first gear 65 side.

[0041] As described above, the embodiments of the present invention have been explained. However, the present invention is not limited to the above - described embodiments, and can be appropriately modified without departing from the gist thereof. In the chain tensioning mechanism 50 of this embodiment, as shown in FIG. 1, the first gear 65 of the adjustment dial 60 and the second gear 71 of the rotation transmission member 70 are spur gears. However, as long as the gears rotate around an axis extending in the left - right direction, the type of gear is not limited. For example, the first gear 65 and the second gear 71 may be helical gears.

[0042] In the chain tensioning mechanism 50 of this embodiment, the gear ratio of the second gear 71 to the first gear 65 is set between 0.1 and 0.5, but the gear ratio is not limited.

[0043] In the chain tensioning mechanism 50 of this embodiment, the maximum outer diameter of the first gear 65 is formed larger than the maximum outer diameter of the second gear 71, but the sizes of the outer diameters of the first gear 65 and the second gear 71 are not limited.

Explanation of Reference Numerals

[0044] 1 Chainsaw 10 Chainsaw body 11 Cover 20 Guide bar 21 Slide groove 25 Connecting hole 30 Saw chain 50 Chain tensioning mechanism 60 Adjustment dial 62 Cylindrical member 64 Rib 65 First gear 66 Grip part 70 Rotation transmission member 71 Second gear 72 First bevel gear 80 Feed screw member 81 Thread groove 82 Second bevel gear 90 Slide member 91 Connecting pin

Claims

1. A chainsaw having a chainsaw body and a guide bar extending in the front-rear direction, wherein the rear part of the guide bar is connected to the chainsaw body, and further comprising a chain tensioning mechanism for adjusting the tension of a saw chain wound around the outer peripheral part of the guide bar, the chain tensioning mechanism including a resin-made cylindrical adjustment dial rotatable about a horizontal axis on the outer surface of the chainsaw body, a metal-made rotation transmission member rotatable about a horizontal axis, a metal-made feed screw member rotatable about a vertical axis inside the chainsaw body, and a slide member connected to the guide bar, the slide member being screwed onto the feed screw member and moving in the front-rear direction as the feed screw member rotates, a first gear formed on the outer peripheral surface of the adjustment dial meshing with a second gear formed on the outer peripheral part of the rotation transmission member, and a first bevel gear formed on the rotation transmission member meshing with a second bevel gear formed on the feed screw member, characterized in that the adjustment dial and the first gear are a single part.

2. The chainsaw according to claim 1, wherein the first gear and the second gear are spur gears arranged in parallel inside the chainsaw body.

3. The chainsaw according to claim 1 or claim 2, wherein the maximum outer diameter of the first gear is formed larger than the maximum outer diameter of the second gear.

4. The chainsaw according to claim 3, wherein the gear ratio of the second gear to the first gear is set between 0.1 and 0.

5.

5. The chainsaw according to claim 3 or claim 4, wherein the ratio of the maximum outer diameter of the first gear to the maximum outer diameter of the second gear is 2:1 to 8:

1.

6. The chainsaw according to claim 3 or claim 4, wherein the ratio of the maximum outer diameter of the first gear to the maximum outer diameter of the second gear is 4:1 to 5:

1.

7. The chainsaw according to any one of claims 1 to 6, wherein a gripping part is formed at a tip-side part of the adjustment dial, and the first gear is formed at a base-side part of the adjustment dial. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ A chainsaw, characterized in that the ratio of the maximum outer diameter of the gripping part to the maximum outer diameter of the second gear is 4:1 to 5:

1.

8. The chainsaw according to any one of Claims 1 to 7, wherein ribs extending in the circumferential direction project from the outer peripheral surface of the adjustment dial, and the first gear is formed at a part on the base end side of the rib in the outer peripheral part of the adjustment dial.

Images