JP2010004778A - Portable working implement - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a portable working implement capable of attenuating its own torsional vibrations, and enabling its own output to be improved and its own maintenance to be facilitated. <P>SOLUTION: The portable working implement is such that, as at least part of a drive shaft 5 is composed of a flexible shaft 51, torsional vibrations developed in the drive shaft 5 can be attenuated owing to the flexible shaft 51; as there is provided a thin-walled cylindrical sleeve 52 threaded through the flexible shaft 51, the flexible shaft 51's meandering can be prevented, further attenuating the vibrations developed in the drive shaft 5; in addition, as the sleeve 52 rotates integratedly with the flexible shaft 51, the flexible shaft 51 is subjected to no friction with the sleeve 52, enabling the implement's output to be increased that much; besides, as the flexible shaft 51 is subjected to no friction with the sleeve 52, lubricant coating on the flexible shaft 51 can be made unnecessary, thus facilitating the implement's maintenance. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a portable work machine.

  Conventionally, a mower for mowing is known as a portable work machine. In the brush cutter, the rotation of the engine provided at one end of the long outer pipe is transmitted to the drive shaft passing through the outer pipe, and is transmitted from the drive shaft to the cutting blade provided at the other end of the outer pipe. . A handle that is gripped by the user is attached to the outer pipe.

  In such a brush cutter, when there is rapid acceleration / deceleration or torque fluctuation of the engine, a torsional vibration is generated in the drive shaft, and this vibration is transmitted to the handle via the outer pipe. For such a problem, a brush cutter that attenuates torsional vibration by configuring the drive shaft with a flexible flexible shaft is known (for example, see Patent Document 1). In this brush cutter, a liner that rotatably holds the flexible shaft is installed in the outer pipe, and by this liner, the flexible shaft is prevented from wobbling (twisting and ramping), thereby damping the torsional vibration caused by the flexible shaft. The effect is further improved. In this brush cutter, a lubricant is applied to the flexible shaft to reduce the friction between the flexible shaft and the liner, thereby suppressing a decrease in output due to the friction and the frictional heat between the liner and the flexible shaft. Prevents melting.

No. 02-19003

  However, in this brush cutter, although the lubricant is applied to the flexible shaft and the friction between the flexible shaft and the liner is reduced, there is still a problem that the friction and output loss occur. . Further, in this brush cutter, as described above, in order to prevent the liner from melting due to frictional heat with the flexible shaft, it is necessary to periodically apply a lubricant to the flexible shaft, which takes time and effort for maintenance. There's a problem.

  An object of the present invention is to provide a portable work machine that can attenuate torsional vibration, improve output, and facilitate maintenance.

  A portable work machine according to a first aspect of the present invention includes a work tool, an engine having an output shaft, an outer pipe that connects the work tool side and the engine side, and at least a part thereof is a flexible shaft. And a drive shaft that is rotatably held in the outer pipe and transmits the rotation of the output shaft to the working tool, and a thin cylindrical sleeve that is inserted through the flexible shaft and rotates integrally with the flexible shaft; It is characterized by having.

  A portable work machine according to a second aspect of the present invention is the portable work machine according to the first aspect, characterized in that the drive shaft includes a hollow cylindrical straight shaft.

  The portable work machine according to claim 3 of the present invention is the portable work machine according to claim 2, wherein the flexible shaft is inserted into one end of the straight shaft and directly connected to the straight shaft. It is characterized by.

  A portable work machine according to a fourth aspect of the present invention is the portable work machine according to any one of the first to third aspects, wherein the flexible shaft constitutes a part of the drive shaft on the engine side. It is characterized by that.

According to the first aspect of the present invention, since at least a part of the drive shaft is configured by the flexible shaft, the torsional vibration generated in the drive shaft can be attenuated by the flexible shaft. Therefore, vibration transmitted from the drive shaft to the handle provided on the outer pipe via the outer pipe can be reduced.
Moreover, since the thin cylindrical sleeve inserted by the flexible shaft is provided, the sleeve can prevent the flexible shaft from wobbling. Therefore, vibration generated in the drive shaft by the flexible shaft can be further damped.
In addition, since the sleeve rotates integrally with the flexible shaft, the flexible shaft does not rub against the sleeve, and the output can be improved accordingly. Moreover, since the flexible shaft does not rub against the sleeve, it is unnecessary to apply a lubricant to the flexible shaft, and maintenance can be facilitated.

  According to the invention of claim 2, since the hollow cylindrical straight shaft is used as the component of the drive shaft, the drive shaft can be reduced in weight while ensuring the rigidity of the drive shaft.

  According to the invention of claim 3, since the flexible shaft is inserted into one end of the straight shaft and directly connected to the straight shaft, compared to the case where the flexible shaft is connected to the straight shaft via the joint member, The number of parts can be reduced.

  According to the invention of claim 4, since the flexible shaft constitutes the engine side having a large torque fluctuation in the drive shaft, the flexible shaft constitutes the work tool side of the drive shaft having a relatively small torque fluctuation. In comparison, the torsional vibration can be effectively attenuated.

[First Embodiment]
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a first embodiment of the invention will be described with reference to the drawings.
FIG. 1 is a perspective view showing a brush cutter 1 as a portable work machine according to the present embodiment.
As shown in FIG. 1, the brush cutter 1 includes an engine 2, an outer pipe 3 provided with the engine 2 at one end, a work tool 4 provided at the other end of the outer pipe 3, and an inner part of the outer pipe 3. A drive shaft 5 (see FIG. 2) that is rotatably held and transmits the rotation of the engine 2 to the work tool 4 is provided. In the middle of the outer pipe 3, a handle 6 and a grip 7 that are gripped by an operator are provided. Further, an accelerator lever 8 for performing an output operation of the engine 2 while gripping the grip 7 is provided in the vicinity of the grip 7. The work tool 4 includes a gear case 41 provided at the other end of the outer pipe 3, and a nylon cutter 42 attached to the gear case 41 and to which rotation is transmitted from the drive shaft 5 via the gear case 41.

FIG. 2 is a cross-sectional view showing the drive shaft 5. In FIG. 2, the handle 6 is omitted.
As shown in FIG. 2, the drive shaft 5 is formed in a straight line, one end is connected to the output shaft 22 of the clutch drum 21 on the engine 2 (FIG. 1) side, and the other end is connected to the gear case 41. As a whole, it is rotatably held by a plurality of bushes 31 (bearings) provided in the outer pipe 3.

FIG. 3 is an enlarged view showing a main part of the drive shaft 5.
The drive shaft 5 includes a flexible shaft 51, a sleeve 52, a joint member 53, and a straight shaft 54.

  The flexible shaft 51 is configured by winding a plurality of wires and has flexibility. The flexible shaft 51 is formed in a circular cross section, and both ends 511 and 512 are ground into a square cross section. An end portion 511 on the engine 2 side is inserted into an insertion hole 221 having a quadrangular section in the output shaft 22 of the clutch drum 21, and an end portion 512 on the work tool 4 side is inserted into the joint member 53.

The flexible shaft 51 constitutes a part of the drive shaft 5. Thereby, in this embodiment, the torsional vibration produced in the drive shaft 5 by this flexible shaft 51 can be attenuated, and the vibration transmitted from the drive shaft 5 to the handle 6 via the outer pipe 3 can be reduced. .
Here, as described in the background art, the flexible shaft has been conventionally used as a component of the entire drive shaft. However, in this case, when the engine is accelerated or decelerated, the drive shaft is once twisted and then transmits the rotation to the work tool. Therefore, the followability of the drive shaft to the engine is reduced, and consequently the work tool for the engine. There is a risk that the followability of the will decrease.

  On the other hand, in this embodiment, since the flexible shaft 51 is used only for part of the drive shaft 5, the amount of twist of the drive shaft 5 when the engine 2 is accelerated or decelerated can be reduced. Accordingly, the followability of the drive shaft 5 with respect to the engine 2 can be improved, and as a result, the followability of the work tool 4 with respect to the engine 2 can be improved. Thereby, blurring of the work tool 4 can be suppressed.

  In addition, the magnitude of the torsional vibration generated in the drive shaft 5 is greatly influenced by the straightness of the drive shaft 5. In this embodiment, the flexible shaft 51 is used as a part of the linear drive shaft 5, so that the flexible shaft 51 is flexible. Torsional vibration can be sufficiently damped by the shaft 51.

  Further, the flexible shaft 51 constitutes a part of the drive shaft 5 on the side of the engine 2 having a large torque fluctuation. Thereby, in this embodiment, the torsional vibration can be effectively attenuated as compared with the case where the working tool 4 side of the drive shaft 5 having a relatively small influence of torque fluctuation is configured by the flexible shaft 51.

Around such a flexible shaft 51, for example, a thin cylindrical sleeve 52 made of a carbon steel pipe for machine structure and having a thickness of about 1 mm is provided in close contact with the flexible shaft 51. In the present embodiment, the sleeve 52 can prevent undulation of the flexible shaft 51 and can further attenuate the vibration generated in the drive shaft 5 by the flexible shaft 51.
The end of the sleeve 52 on the working tool 4 side is inserted into the joint member 53, and the sleeve 52 is provided integrally with the flexible shaft 51 by the joint member 53. That is, the sleeve 52 is provided by the joint member 53 so as to rotate integrally with the flexible shaft 51. Thereby, in this embodiment, since the flexible shaft 51 does not rub against the sleeve 52, the output can be improved accordingly. Further, since the flexible shaft 51 does not rub against the sleeve 52, it is unnecessary to apply a lubricant to the flexible shaft 51, and maintenance can be facilitated.

FIG. 4 is a cross-sectional view showing the joint member 53.
The joint member 53 is formed with an insertion hole 531 into which the flexible shaft 51 and the sleeve 52 are inserted. The insertion hole 531 is formed with a first hole portion 532 having a circular cross section through which the flexible shaft 51 and the sleeve 52 are inserted, and a second hole portion 533 into which the flexible shaft 51 is inserted. And. Among these, the sleeve 52 is joined to the inner peripheral surface of the first hole portion 532 by brazing welding.

  That is, the flexible shaft 51 is inserted into the sleeve 52 joined to the inner peripheral surface of the joint member 53 and is inserted into the second hole 533 of the joint member 53 so that the flexible shaft 51 is detachably connected to the joint member 53. And is integrated with the sleeve 52 and rotates integrally with the sleeve 52. Thus, in this embodiment, since the flexible shaft 51 is detachably connected to the clutch drum 21 and the joint member 53 by being inserted into the clutch drum 21 and the joint member 53, it is easy to be damaged. It can be exchanged, and convenience can be improved. A straight shaft 54 is connected to the bottom surface of the joint member 53 by friction welding.

  The straight shaft 54 transmits the rotation transmitted from the output shaft 22 of the engine 2 through the flexible shaft 51 and the joint member 53 to the work tool 4. The straight shaft 54 is formed in a hollow cylindrical shape. Thus, in this embodiment, since the hollow cylindrical thing was used as the straight shaft 54 which comprises most drive shafts 5, weight reduction can be achieved, ensuring sufficient rigidity. An input shaft 411 (FIG. 2) of the work tool 4 is connected to the other end of the straight shaft 54 by friction welding.

[Second Embodiment]
FIG. 5 is an enlarged view showing a main part of the brush cutter 1B according to the second embodiment of the present invention. Hereinafter, the same functional parts as those already described are denoted by the same reference numerals, and the description thereof is omitted.
The brush cutter 1 </ b> B of the present embodiment has the same configuration as that of the above embodiment, and can achieve the same effects as the above embodiment. However, in the above embodiment, the flexible shaft 51 is straight through the joint member 53. Although it was connected with the shaft 54, in the present embodiment, the flexible shaft 51 is different from the above-described embodiment in that it is directly connected to the straight shaft 54.

  In the present embodiment, after the flexible shaft 51 is inserted into the sleeve 52, the central portion of the sleeve 52 is caulked at four positions at intervals of 90 degrees in the circumferential direction, so that the flexible shaft 51 is provided integrally with the sleeve 52. The end 512 on the working tool 4 side of the flexible shaft 51 is formed in a circular cross section and is directly press-fitted into the straight shaft 54.

FIG. 6 is an enlarged view showing a main part of the straight shaft 54.
The straight shaft 54 includes a shaft main body 541 and an insertion portion 542. The insertion portion 542 is a cylindrical member having an inner diameter larger than the inner diameter of the shaft main body 541, and is connected to the end of the shaft main body 541 on the engine 2 side by friction welding. In the present embodiment, the flexible shaft 51 is press-fitted into the insertion portion 542 so that the straight shaft 54 and the flexible shaft 51 are directly connected to each other, so that the flexible shaft 51 and the straight shaft 54 are connected via the joint member 53. Compared to the case where the joint members 53 are connected, the number of parts can be reduced by the amount that the joint member 53 can be omitted. The insertion portion 542 is rotatably held by the bush 31 (FIG. 5).

[Modification of Embodiment]
It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
For example, in the second embodiment, the flexible shaft 51 is connected to the straight shaft 54 by being press-fitted into the insertion portion 542 of the straight shaft 54, but the flexible shaft 51 is connected to the insertion portion 542 of the straight shaft 54. After the insertion, the insertion portion 542 may be crimped to be connected to the straight shaft 54. Further, the flexible shaft 51 may be coupled to the straight shaft 53 by being press-fitted into the insertion portion 532 and then the insertion portion 532 being crimped.

In each of the embodiments described above, the flexible shaft 51 is used in a straight line. However, the flexible shaft 51 performs rotation output toward the user's back side in a shoulder-type brush cutter or the like in front of the user. It may be curved and used to change the direction to the side.
In each of the above embodiments, the flexible shaft 51 constitutes a part of the drive shaft 5 on the engine 2 side, but the flexible shaft may constitute a part of the drive shaft on the work tool 4 side. Even in this case, since a part of the linear drive shaft is constituted by the flexible shaft, the torsional vibration generated in the drive shaft by the flexible shaft can be sufficiently damped.
In each said embodiment, although the flexible shaft 51 was used as what comprises only a part of drive shaft 5, the flexible shaft 51 may be used as what comprises the drive shaft 5 whole.

In each of the embodiments described above, the both end portions 511 and 512 of the flexible shaft 51 are formed in a quadrangular cross section. The cross section may be circular.
In each of the above embodiments, the straight shaft 54 is formed hollow, but the straight shaft may be formed solid.

In each of the above-described embodiments, an example in which the present invention is applied to a brush cutter has been described. For example, it can be applied to a high branch pruning machine or a reaper.
In each of the embodiments described above, the work tool is configured to include the nylon cutter, but the work tool may be configured in any manner as long as the work is transmitted by the rotation from the engine. The tool may comprise a disk-shaped cutting blade and a pruning attachment.

  INDUSTRIAL APPLICABILITY The present invention can be suitably used for portable work machines such as a brush cutter and a high branch pruner.

The perspective view which shows the brush cutter which concerns on 1st Embodiment of this invention. Sectional drawing which shows a drive shaft. The enlarged view which shows the principal part of a drive shaft. Sectional drawing which shows a coupling member. The enlarged view which shows the principal part of the brush cutter which concerns on 2nd Embodiment of this invention. The enlarged view which shows the principal part of a straight shaft.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Brush cutter (portable working machine), 2 ... Engine, 3 ... Outer pipe, 4 ... Work tool, 5 ... Drive shaft, 51 ... Flexible shaft, 52 ... Sleeve, 54 ... Straight shaft

Claims (4)

Work tools,
An engine having an output shaft;
An outer pipe connecting the work tool side and the engine side;
A drive shaft that is at least partially configured by a flexible shaft, is rotatably held in the outer pipe, and transmits the rotation of the output shaft to the working tool;
A portable work machine comprising: a thin cylindrical sleeve inserted through the flexible shaft and rotating integrally with the flexible shaft. The portable work machine according to claim 1, wherein
The drive shaft is provided with a hollow cylindrical straight shaft. The portable work machine according to claim 2, wherein
The said flexible shaft is inserted in the end of the said straight shaft, and is directly connected with the said straight shaft. The portable working machine characterized by the above-mentioned. The portable work machine according to any one of claims 1 to 3,
The flexible shaft constitutes a part of the drive shaft on the engine side.

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