JPS6039201Y2 - Chain tension mechanism in chainsaw - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of the chain tensioning mechanism of a chainsaw.

FIG. 1 is a front view of a conventional chainsaw, showing the structure of the outer frame member 2 with a part of the sprocket cover 3 cut away.

An end portion of a guide bar 4 is accommodated in a sprocket cover 3 attached to an outer frame member 2, and a chain 5 around which a sprocket 1 is wound is attached to the outer periphery of the guide bar 4.

The outer frame member 2 has a protruding surface 7 that comes into contact with one side of the guide bar 4.
etc., and the rear surface of the sprocket cover 3 is also provided with a surface that comes into contact with the guide bar 4. Therefore, insert the bolt 14 from above the sprocket cover 3, pass it through the hole in the guide bar 4, and insert it into the screw hole 6. The guide bar 4 is fixed by screwing.

That is, the guide bar 4 is clamped and fixed between the outer frame member 2 and the sprocket cover 3.

Further, a tension component 9 is installed in a groove 12 provided in the longitudinal direction of the guide bar 4 in the outer frame member 2, and an adjustment screw 8 is screwed into the tension component 9.

FIG. 2 is a sectional view taken along the line AA in FIG. 1, and is a diagram illustrating a mechanism for adjusting the tension of the chain of the guide bar 4. FIG.

The guide bar 4 is held between the outer frame member 2 and the sprocket cover 3, and the small diameter part 1 of the tensioning part 9 is inserted into the hole 11 of the guide bar 4.
Inserting 0.

This tension component 9 is inserted into a groove 12 of the outer frame member 2, and is screwed through the adjustment screw 8 from the lateral direction.

To adjust the tension of the chain 5, loosen the bolt screwed into the screw hole 6 in FIG.

Once the tension of the chain 5 is appropriate, tighten the bolts 14 and attach the outer frame member 2 and sprocket cover 3.
Clamp and fix the guide bar 4 again.

Figure 3 is a plan view of the chainsaw in Figure 1, with chain 5
It shows the adjustment state by the driver 13 when adjusting the tension of the.

As shown in FIG. 2, the adjusting screw 8 is close to the guide bar 4, and in order to rotate it, the driver 13 must be inserted from an oblique direction, so it is difficult to rotate the adjusting screw 8.

Therefore, it is difficult to adjust the tension of the chain 5, and the driver groove of the adjusting screw 8 may be damaged.

Note that 14 in FIG. 3 is a bolt that tightens the sprocket 3 in order to fix the guide bar 4.

The purpose of this invention is to provide a chain tensioning mechanism for a chainsaw that can always maintain proper chain tension, and its feature is that it covers the area including the tensioning part insertion hole of the sprocket and guide bar. A tensioning component and an elastic member that presses the tensioning component with a predetermined pressure in the direction opposite to the sprocket are accommodated in a groove provided in the recess of the sprocket cover, and the tensioning component is pushed against the pressing force of the elastic member. The lever for moving the sprocket in the direction closer to the sprocket is attached to the concave portion of the sprocket cover.

FIG. 4 is a front view showing the main parts of a chainsaw according to an embodiment of the present invention, with the cover 15 covering the recess 19 of the sprocket cover 3 being cut away to show the chain tension adjustment mechanism.

The same parts as in FIG.
It is incorporated into.

A groove 18 in the longitudinal direction of the guide bar 4 is formed in the recess 19 of the sprocket cover 3, and a coil spring 17 and an adjustment part 9 are inserted into this groove 18, and the fulcrum is fixed in the recess 19 in an L-shape. The contact end 27 of the lever 21 is brought into contact with the adjustment component 9.

The cover 15 is screwed to cover the lever 21 other than the operating end 22, and is further secured to the outer frame member 2 by bolts 14.
The guide bar 4 is clamped and fixed between the sprocket cover 3 and the outer frame member 2.

Note that the operating end 22 of the lever 21 can be moved from the outside within the range of rib end surfaces 23 and 24 provided on the cover 15.

FIG. 5 is a sectional view taken along line BB in FIG. 4.

The small diameter portion 10 of the tensioning element 9 installed in the groove 18 passes through a slot 20 formed at the bottom of the groove 18 and fits into the hole 11 of the guide bar 4.

Further, the tension component 9 is in contact with the contact end 27 of the lever 21, and is constantly receiving a force from the coil spring 17 that pushes the guide bar 4 outward.

However, when the bolts 14 are tightened, the guide bar 4 is clamped and fixed between the outer frame member 2 and the back surface of the groove 18 of the sprocket cover 3.

The rope, the cover 15 has the coil spring 17 and the tension part 9 in the groove 1.
A thick part is provided to prevent it from jumping out from the 8.

FIG. 6 is a back view of the sprocket cover 3 shown in FIG. 4, and the left and right direction is opposite to that shown in FIG. 4.

16 is a contact surface that contacts the guide bar 4; 20 is a slot through which the small diameter portion 10 of the adjustment component 9 passes; 25 is a bolt 1;
This is a hole provided for inserting 4.

FIG. 7 is a perspective view of the lever of FIG. 4, in which the operating end 22 and the contact end 27 with the tensioning part 9 are shaped, and the lever is rotatably mounted in the recess 19 of the sprocket cover 3 by inserting a screw into the hole 26. It will be done.

FIG. 8 is a sectional view taken along the line CC in FIG. 4.

The tension part 9 is installed in the groove 18 of the sprocket cover 3 and is held down by the thick part of the cover 15.

The guide bar 4 is held between the contact surfaces 16 of the outer frame member 2 and the sprocket cover 3, and has a chain 5 wound around its outer periphery.

In the chainsaw constructed as described above, when the bolt 14 shown in FIG. 4 is first loosened, the coil spring 17, together with the tension member 9, pushes the guide bar in the opposite direction to the sprocket, so that the chain 5 becomes tensioned.

In this case, if the strength of the coil spring 17 is set appropriately, a predetermined tension force can be applied to the chain 5.

Note that when the operating end 22 of the lever 21 is rotated in the D direction until it comes into contact with the rib 23 with the bolt 14 loosened as described above, the loosening of the chain 5 increases.

If the bolts 14 are removed in this state, the guide bar 4 can be easily removed together with the sprocket cover 3.

When a chainsaw is used for a long time, the connecting part of the chain 5 wears out and gradually stretches, but the tension of the chain 5 can be corrected to a suitable state by slightly loosening the bolt 14 and performing an extremely simple operation.

Therefore, the difficult adjustment work using a conventional screwdriver is eliminated, and the tension of the chain 5 can also be maintained at an optimum state, improving the operating efficiency of the chainsaw.

The chain tensioning mechanism of this embodiment accommodates a coil spring and adjustment parts fitted into holes in the guide bar in a groove in the longitudinal direction of the guide bar provided in the recess of the sprocket cover.
A lever is provided that allows the position of the tensioning part to be adjusted from the outside, and a bolt is provided to clamp the guide bar between the sprocket cover and the outer frame member.

When adjusting the chain tension, the simple operation of loosening this bolt provides the effect of easily adjusting the chain tension to a suitable state.

In the above embodiment, the coil spring 17 is used as the elastic member for moving the tension component 9, but other elastic members,
For example, a small bellows or the like may be compressed and installed.

The chain saw chain tensioning mechanism of the present invention has the advantage that the tension of the chain can be easily adjusted with a simple configuration.

[Brief explanation of drawings]

Fig. 1 is a front view of a conventional chainsaw, Fig. 2 is a sectional view taken along line A-A in Fig. 1, Fig. 3 is a plan view of the chainsaw shown in Fig. 1, and Fig. 4 is an embodiment of the present invention. A front view showing the main parts of the chainsaw, Figure 5 is a sectional view taken along line B-B in Figure 4, Figure 6 is
7 is a perspective view of the lever shown in FIG. 4, and FIG. 8 is a sectional view taken along the line CC in FIG. 4. 1...Sprocket, 2...Outer frame member, 3...Sprocket cover, 4...
Guide bar, 5...Chain, 9...
Tension part, 10...Small diameter part, 11...
Hole, 14... Bolt, 15... Cover 16... Contact surface, 17... Coil spring, 18... Groove, 19・・・・・・Concavity, 20
...Slot hole, 21...Lever, 22...
...Operation end, 23, 24...Rib end surface, 2
5...hole, 27...contact end.

Claims (1)

[Scope of utility model registration request] In a chain saw, the chain is tensioned by moving a guide bar around which a chain driven by a sprocket is wound, and a tensioning part fitted into a hole provided in the guide bar. The tension component and an elastic member that presses the tension component in a direction opposite to the sprocket are accommodated in a groove provided in a recess of the sprocket cover that covers an area including the hole, and the tension component is moved by the pressing force of the elastic member. A chain tensioning mechanism for a chainsaw, characterized in that a lever for moving the sprocket in a direction toward the sprocket is attached to a recess in the sprocket cover.