JP4801961B2 - Chainsaw - Google Patents

Description

  The present invention relates to a chain saw in which a guide bar is provided in a housing incorporating a motor, and a material to be cut is cut by rotating the chain along the guide bar.

The chain saw is supported in a housing with a motor that is driven by turning on the trigger. The spindle that rotates by driving the motor is supported laterally, and a sprocket that rotates by the rotation of the spindle is projected to the side of the housing. And a chain is stretched between the sprocket and the guide bar. Therefore, by rotating the chain along the peripheral edge of the guide bar by the rotation of the sprocket, it becomes possible to cut a workpiece such as a log.
In such chainsaws, if the trigger is turned OFF to stop energization of the motor and the chain rotation due to inertia is left unattended, the work piece will be damaged or workability will be deteriorated. A so-called electric brake is often used in which a brake circuit having a brake winding is provided in addition to this drive circuit, and the brake circuit is closed when the trigger is turned off to apply a reverse current to the motor for braking.

  However, with only the electric brake, the chain does not stop simultaneously with the timing when the trigger is turned OFF, and some braking time occurs. Therefore, in the patent document 1, the applicant of the present invention provided the first cam integrally with the sprocket, and on the spindle, urged the second cam that can mesh with the first cam to rotate separately and to the first cam side. A steel ball is provided on the outer peripheral surface of the spindle by providing a guide groove comprising an inclined portion and a circumferentially engaging portion, and an axial connecting groove on the inner peripheral surface of the second cam. An invention of a clutch mechanism for fitting the two is provided. According to this clutch mechanism, at the time of starting rotation of the spindle, the second cam is advanced by a rotational difference generated between the second cam and meshed with the first cam. When the spindle is braked by an electric brake, the second cam is engaged with the second cam. On the other hand, the second cam is retracted due to the rotation difference that causes the spindle to be delayed, and the connection with the first cam is released upon reaching the locking portion, so that the chain braking time can be shortened compared to the braking time of the electric brake alone.

Japanese Unexamined Patent Application Publication No. 2004-314442

  However, in the present invention, since the electric brake is indispensable for the operation of the clutch mechanism, there is a problem that the braking mechanism cannot be operated and the braking time cannot be shortened when the electric brake causes a malfunction. In addition, since a reverse current brake winding is required for the motor, miniaturization of the motor is hindered, leading to an overall increase in size, and the main winding of the motor cannot be secured sufficiently, limiting the maximum output. It will also be received.

Therefore, the present invention can effectively reduce the chain braking time without requiring an electric brake, and can be expected to be compact and increase the maximum output even if such a clutch mechanism is used. Is intended to provide.

In order to achieve the above object, according to a first aspect of the present invention, a spindle is provided with a centrifugal clutch that projects a weight member in a radial direction by rotation of the spindle, while a sprocket is provided with a first cam tooth on the centrifugal clutch side. And a connecting body that protrudes to the outer peripheral side of the centrifugal clutch and can contact when the weight member protrudes, and can be engaged with the first cam teeth on the surface facing the cam in the centrifugal clutch. A second cam tooth is formed, and either one of the outer peripheral surface of the spindle and the inner peripheral surface of the centrifugal clutch is fitted with a guide groove inclined at a predetermined lead angle from the spindle axial direction, and the other is fitted into the guide groove. While providing each connecting portion to be provided, providing a biasing means for biasing the centrifugal clutch in the direction away from the cam,
When the motor is started, the centrifugal clutch is moved to the cam side due to the rotation difference generated between the spindle and the centrifugal clutch to engage the cam teeth, and the centrifugal clutch is protruded by the protrusion of the weight member of the centrifugal clutch as the spindle rotates. By integrating the clutch with the coupling body, the sprocket is rotated integrally with the spindle, and when the energization to the motor is stopped from the driving state, the spindle member of the centrifugal clutch is separated from the coupling body due to the decrease in the rotation of the spindle. At the same time, the centrifugal clutch is separated from the cam by the urging means, so that the integral rotation of the spindle and the sprocket is cut off.

  According to a second aspect of the present invention, in addition to the object of the first aspect, in order to increase the reliability of the clutch operation, a cam is provided on at least one of the first cam teeth of the cam and the second cam teeth of the centrifugal clutch. An inclined surface is provided that presses each other in the direction away from each other by interference with the other cam teeth accompanying the rotation difference from the centrifugal clutch.

According to the first aspect of the present invention, it is possible to effectively shorten the chain braking time without providing an electric brake. In particular, the rotation transmission from the spindle to the cam side and the interruption thereof are stably and reliably performed by employing the centrifugal clutch. In addition, by eliminating the need for an electric brake, miniaturization of the motor can be achieved with the same output, leading to overall compactness. With the same size, the main winding of the motor can be secured sufficiently because no brake winding is provided. The maximum output can be increased.
According to the second aspect of the present invention, in addition to the effect of the first aspect, the cam and the centrifugal clutch are reliably separated when the energization of the motor is stopped, and the reliability of the clutch operation is increased.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a partial longitudinal sectional view showing an example of a chain saw, and FIG. 2A is a partial transverse sectional view. The chain saw 1 houses a motor 3 in a housing 2 facing forward (the right side in FIGS. 1 and 2 is the front), and a spindle 7 and an output shaft 4 by ball bearings 5 and 6 in front of the output shaft 4. The rotation of the output shaft 4 can be transmitted to the spindle 7 by engaging the bevel gears 8 and 9 fixed to the output shaft 4 and the spindle 7, respectively, in such a manner that they are axially supported in a transverse direction. Further, an end portion of the spindle 7 opposite to the bevel gear 9 penetrates the housing 2 and protrudes to the side, and a flange 12 is extended to the protruding end portion 10 on the inner side (ball bearing 6 side). A cylindrical cam 11 is externally rotatably mounted, and a sprocket 13 is fixed to the cam 11 so as to be integrally rotatable. A flat guide bar 15 is fixed to the side surface of the housing 2 in front of the sprocket 13 by a fixing bolt 14 so as to protrude forward, and an endless shape is provided between the sprocket 13 and the periphery of the guide bar 15. A chain 16 is stretched. Therefore, when the sprocket 13 rotates, the chain 16 rotates along the groove 17 provided in the periphery of the guide bar 15.

  On the other hand, between the cam 11 and the ball bearing 6 in the spindle 7, a centrifugal clutch 18 having a disc shape larger than the flange 12 of the cam 11 is coaxially and orthogonally mounted on the spindle 7. This centrifugal clutch 18 is a well-known example in which three weight members 19, 19... Connected to the outer periphery in a radial direction are connected to each other in the circumferential direction by connecting springs 20, 20. In this form, between the flange 12 and the sprocket 13 in the cam 11, the inner opening has a slightly larger inner diameter than the outer diameter of the centrifugal clutch 18, and the centrifugal clutch 18 is in a normal state (when the motor 3 is stopped). The dish-like connecting body 21 that is covered in a non-contact manner is fitted so as to be rotatable together. A washer 22 is sandwiched and fixed between the flange 12 and the connecting body 21.

  On the inner peripheral surface of the centrifugal clutch 18, axially connecting grooves 23, 23,... That are open on the ball bearing 6 side are recessed at three locations equally in the circumferential direction. On the other hand, on the outer peripheral surface of the spindle 7, guide grooves 24, 24,... That are inclined at a predetermined lead angle from the axis of the spindle 7 are similarly recessed at three locations in the circumferential direction. A steel ball 25 serving as a connecting portion is fitted between the guide groove 24 and the guide groove 24. Therefore, the centrifugal clutch 18 can move back and forth in the axial direction with respect to the spindle 7 within a range in which each steel ball 25 rolls in the guide groove 24 and rotates integrally with the spindle 7. A coil spring 26 as an urging means is interposed between the clutch 18 and the centrifugal clutch 18. When the motor 3 is stopped, the steel ball 25 is inserted into the rear end of the guide groove 24 (for the spindle 7 and the centrifugal clutch 18. In the axial direction of the spindle 7, the protruding end portion 10 side is described as being forward.

  Further, on the opposing surfaces of the flange 12 of the cam 11 and the centrifugal clutch 18, as shown in FIG. 4, cam teeth 27, 27... Having the same shape as the first cam teeth and the second cam teeth are respectively provided. Is formed. The cam teeth 27, 27... Have a shape in which one of the circumferential directions is a gentle slope 28 and the other is a steep slope 29 (the inclined surface of the present invention), and is projected at six locations at equal intervals in the circumferential direction. Yes. Therefore, when the centrifugal clutch 18 moves forward to the flange 12 side, the cam teeth 27 and 27 mesh with each other.

In the chain saw 1 configured as described above, when the motor 3 shown in FIG. 2 is stopped, the centrifugal clutch 18 is in the retracted position away from the flange 12 of the cam 11 by the bias of the coil spring 26 as described above. The weight member 19 of the clutch 18 is also in the contracted position where it does not come into contact with the coupling body 21.
Here, when a trigger (not shown) provided in the housing 2 is turned on to energize the motor 3 and the motor 3 is driven, the spindle 7 rotates via the bevel gears 8 and 9 by the rotation of the output shaft 4 (in FIG. 1). To the right). Since the rotation of the spindle 7 causes a rotation difference between the centrifugal clutch 18 and the centrifugal clutch 18 with respect to the spindle 7, the centrifugal clutch 18 is rotated while rolling each steel ball 25 forward along the guide groove 24. Advances against the bias of the coil spring 26. At this forward position, the cam 11 abuts against the cam 11 to engage the cam teeth 27, 27 (FIG. 3).

  At this time, when the centrifugal force acting on the weight member 19 by the rotation of the centrifugal clutch 18 following the spindle 7 exceeds the contraction biasing force of the connection spring 20, each weight member 19 moves in the radial direction and the connection body 21 Contact the inner surface. Therefore, the cam 11 is connected to the spindle 7 via the centrifugal clutch 18 and the connecting body 21, the sprocket 13 rotates together with the cam 11, and the chain 16 rotates along the guide bar 15. The material to be cut can be cut by.

When the trigger is turned OFF by the end of the cutting and the motor 3 is de-energized, the rotational speed of the centrifugal clutch 18 together with the spindle 7 decreases to reduce the centrifugal force to the weight member 19. As a result, the weight member 19 moves in the contracting direction and moves away from the connection body 21, and the rotation transmission to the cam 11 via the connection body 21 is interrupted. Along with the operation of the centrifugal clutch 18, the centrifugal clutch 18 moves backward while rolling the steel balls 25 along the guide grooves 24 by the bias of the coil spring 26, so that the engagement of the cam teeth 27 is released. Return to the position of FIG. At this time, if even a slight rotational difference occurs between the cam 11 and the centrifugal clutch 18, the steep slopes 29 formed on the cam teeth 27 come into contact with each other and press the cam 11 away. Surely done.
Thus, the cam 11 and the sprocket 13 are in a rotation-free state with respect to the spindle 7, but a large braking force acts on the chain 16 and the sprocket 13 due to friction between the guide bar 15 and the chain 16 that rotates while sliding on the periphery thereof. The chain 16 and the sprocket 13 immediately stop rotating.

  As described above, according to the chain saw 1 of the above embodiment, the centrifugal clutch 18 is externally mounted on the spindle 7, while the cam 11 having the cam teeth 27 formed on the sprocket 13 and the coupling body 21 are integrally provided. The cam teeth 27 having the same shape are formed on the surface facing the cam 11, the guide groove 24 is provided on the outer peripheral surface of the spindle 7, and the guide groove 24 is provided on the inner peripheral surface of the centrifugal clutch 18. On the other hand, a coil spring 26 that biases the centrifugal clutch 18 in a direction away from the cam 11 is provided, and when the motor 3 is started, the centrifugal clutch 18 is caused by a rotational difference generated between the spindle 7 and the centrifugal clutch 18. The cam teeth are moved forward and meshed with each other, and the centrifugal clutch 18 is integrated with the coupling body 21 by the protrusion of the weight member 19 of the centrifugal clutch 18. When the sprocket 13 is rotated integrally with the spindle 7 and energization of the motor 3 is stopped from the driving state, the spindle member 19 of the centrifugal clutch 18 is separated from the coupling body 21 due to the rotation reduction of the spindle 7 and the coil spring 26, the centrifugal clutch 18 is separated from the cam 11 so that the integral rotation of the spindle 7 and the sprocket 13 is cut off, so that the braking time of the chain 16 can be effectively shortened without providing an electric brake. It becomes. In particular, the adoption of the centrifugal clutch 18 allows the rotation transmission from the spindle 7 to the cam 11 side and the interruption thereof to be performed stably and reliably. In addition, by eliminating the need for an electric brake, the motor 3 can be reduced in size with the same output, leading to overall compactness. With the same size, the main winding of the motor 3 can be sufficiently secured because no brake winding is provided. It is possible to increase the maximum output.

  Particularly, here, the cam teeth 27 of the cam 11 and the centrifugal clutch 18 are provided with steep slopes 29 that press each other in the direction away from each other by contact with the cam teeth 27 on the other side due to the rotational difference between the cam 11 and the centrifugal clutch 18. As a result, the cam 11 and the centrifugal clutch 18 are reliably separated when the energization of the motor 3 is stopped, and the reliability of the clutch operation is increased.

In the above embodiment, the guide groove is provided on the outer peripheral surface of the spindle and the connection groove is provided on the inner peripheral surface of the centrifugal clutch. However, the guide groove inclined at a predetermined lead angle on the centrifugal clutch side is reversed. In addition, axial connection grooves can be formed on the spindle side, and the centrifugal clutch can be moved forward and backward by the rotational difference between the spindle and the centrifugal clutch. In addition, instead of the steel ball, the connecting portion has, for example, a semicircular protrusion protruding on one of the inner peripheral surface of the centrifugal clutch or the outer peripheral surface of the spindle, and the protrusion is fitted into the other guide groove. A structure for guiding the centrifugal clutch can also be adopted.
Further, the biasing means for the centrifugal clutch is not limited to the coil spring, and other configurations such as a disc spring and a leaf spring can be adopted, and the biasing means is not limited to the compression bias, and may be pulled and biased on the rear side of the centrifugal clutch. good.

Furthermore, in the above embodiment, the cam is structured to be mounted on the protruding end of the spindle. However, the present invention is not limited to this structure, and the rotating shaft of the cam is supported separately from the spindle so that the shaft is not interposed. You may make it make a cam and a centrifugal clutch oppose on the same axis.
Further, the inclined surfaces of the cam teeth that press each other in the direction away from each other when the clutch is operated may be provided on either one of the cam teeth of the cam and the centrifugal clutch. Of course, the number of cam teeth can be increased / decreased and the shape can be changed as appropriate. As shown in FIG. 5, a flat surface 30 along the axial direction may be used instead of the steep slope 29 of the cam teeth 27.

It is a partial longitudinal cross-sectional view of a chainsaw. In the partial cross-sectional view of the chain saw in the motor OFF state, a partial development view of the spindle is also shown on the right side. A partial cross-sectional view of the chain saw in the motor-on state, with a partially developed view of the spindle on the right side. It is explanatory drawing which shows the cam tooth shape in a cam and a centrifugal clutch, the upper side is the front of a cam surface, the center is a side surface, and the lower side shows the expanded view of a cam part. It is explanatory drawing which shows the example of a cam tooth shape change, the upper side is the front of a cam surface, the center is a side surface, and the lower side shows the expanded view of a cam part.

Explanation of symbols

1 ··· Chain saw, 2 · Housing, 3 · Motor, · · · Output shaft, 7 · · Spindle, 11 · · Cam, 12 · · Flange, 13 · · Sprocket, 15 · · Guide bar, 16 · · Chain, 18 ... Centrifugal clutch, 21 ... Connection body, 23 ... Connection groove, 24 ... Guide groove, 25 ... Steel ball, 26 ... Coil spring, 27 ... Cam tooth, 28 ... Slope, 29・ ・ Steep slope.

Claims (2)

A sprocket that horizontally supports a spindle that rotates by driving the motor in a housing having a motor, is arranged on the side of the housing and coaxially with the spindle, and rotates as the spindle rotates. And a guide bar protruding forward from the sprocket, a chain is stretched between the sprocket and the guide bar, and the chain can be rotated along the periphery of the guide bar by the rotation of the sprocket. A chainsaw,
The spindle is provided with a centrifugal clutch that projects a weight member in the radial direction by the rotation of the spindle, while the sprocket has a cam formed with first cam teeth on the centrifugal clutch side, and an outer peripheral side of the centrifugal clutch. A second cam tooth that can be engaged with the first cam tooth on a surface facing the cam in the centrifugal clutch;
One of the outer peripheral surface of the spindle and the inner peripheral surface of the centrifugal clutch has a guide groove that is inclined at a predetermined lead angle from the axial direction of the spindle, and the other is a connecting portion that fits into the guide groove. While providing a biasing means for biasing the centrifugal clutch away from the cam,
When the motor is started, the centrifugal clutch is moved to the cam side by the rotational difference generated between the spindle and the centrifugal clutch to mesh the cam teeth, and the centrifugal clutch accompanying the rotation of the spindle When the centrifugal clutch is integrated with the coupling body by the protrusion of the weight member, the sprocket is rotated integrally with the spindle, and when the energization to the motor is stopped from the driving state, the spindle rotates. The weight member of the centrifugal clutch is separated from the coupling body due to the lowering, and the centrifugal clutch is separated from the cam by the biasing means, so that the integral rotation of the spindle and the sprocket is blocked. A featured chainsaw. At least one of the first cam teeth of the cam and the second cam teeth of the centrifugal clutch is provided with an inclined surface that presses each other in the direction away from each other by contact with the other cam tooth due to the rotational difference between the cam and the centrifugal clutch. The chain saw according to claim 1 provided.

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