JPH0574323B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a working machine such as a brush cutter having an extendable and retractable operating rod in which a transmission shaft is passed through and supported.

BACKGROUND TECHNOLOGY In working machines such as brush cutters, a prime mover such as an internal combustion engine is disposed at the rear end of an extensible and retractable, elongated, tubular operation stick that is held and operated by a worker, and a rotary motor such as an internal combustion engine is disposed at the tip of the operation stick. A power tool such as a brush cutting blade is attached, and a transmission shaft for drivingly connecting the power tool to the prime mover is supported through the inside of the operating rod, so that the power of the prime mover is transmitted to the power tool via the power transmission shaft. With,
The operating rod has an expandable structure so that it can be adjusted to a length suitable for the operator, and the length of the operating rod can be shortened when the working machine is not in use so that the working machine can be stored in a small space. There are some that are configured in

However, with conventional working machines of this type,
Even when the operating stick is shortened from its working length to its storage length, the transmission shaft remains in a state where it can transmit power from the prime mover to the working tool, and for this reason, the operating stick can be shortened. If the prime mover is inadvertently or accidentally energized and the power tool is driven under such conditions, there is a drawback that serious harm may be caused to the operator or the like.

Problems to be Solved by the Invention Therefore, an object of the present invention is to eliminate the drawbacks of the conventional working machines as described above, and to provide a simple and convenient working machine.

Means for Solving the Problems According to the present invention, a working machine having a telescoping operating rod in which a power transmission shaft is passed through and supported therein includes a main rod portion and a telescoping operation rod with respect to the main rod portion. It consists of a movable rod part that can move in the axial direction, and a hollow tubular main transmission shaft is rotatably provided in the main rod part,
A movable transmission shaft that is drivingly connected via a one-way clutch fixed inside the front end portion of the main transmission shaft 6 and that can move in the axial direction in a telescoping manner with respect to the main transmission shaft is rotatable within the movable rod portion. The main transmission shaft is rotatably and relatively slidably supported in the axial direction by a bearing installed in the rear end portion of the movable rod portion, and the front portion of the movable transmission shaft is supported by a bearing installed in the rear end portion of the movable rod portion. The movable transmission shaft is formed to have an outer diameter smaller than the outer diameter, and is configured such that the rear portion of the movable transmission shaft engages with the one-way clutch within an axial length range corresponding to the normally used length of the operating stick. Features.

Function: Therefore, the movable power transmission shaft is drivingly connected to the main power transmission shaft via the one-way clutch when the movable rod portion is within the range corresponding to the normal operating length of the operating rod, but when the operating rod is stored, When the movable rod portion is moved to a position where the driving force is cut off, the movable power transmission shaft is disconnected from the one-way clutch and transmission of the driving force from the main power transmission shaft is cut off.

Embodiments Next, embodiments will be described with reference to the embodiments of the drawings.

The illustrated embodiment is an example in which the present invention is applied to a brush cutter, and this brush cutter has an operating rod 1 that is held and operated by an operator, and the operating rod 1 includes a main rod portion 2 having a hollow tubular shape; It has a movable rod portion 3 having an outer diameter smaller than the inner diameter of the main rod portion 2 and coaxially extending forward from the front end portion of the main rod portion 2. The movable rod portion 3
has a large-diameter rear end portion 4 integrally formed, and the rear end portion 4 is slidably supported in the axial direction on the inner diameter of the main rod portion 2 to move the movable rod portion 3 to the main rod portion 2. Move the operating rod 1 in a nested manner relative to the rod portion 2.
may have an overall length shorter than that shown. The main rod portion 2 and the movable rod portion 3 are connected and fixed to each other by a suitable joint member 5, which is loosened when adjusting the length of the operating rod 1 and the movable rod portion 3
It is configured to be able to slide in the axial direction.

A hollow tubular main transmission shaft 6 is provided inside the main rod portion 2.
The main transmission shaft 6 is rotatably supported at its rear end portion by a bearing 7 mounted inside the main rod portion 2. The front end portion of the main power transmission shaft 6 is supported by a bearing 8 mounted in the rear end portion 4 of the movable rod portion 3 so as to be rotatable and relatively slidable in the axial direction. The rear end portion of the main transmission shaft 6 is connected via a vibration-absorbing flexible transmission shaft 9 to an output shaft 11 of a drum 10 of a centrifugal clutch which is drivingly connected to a prime mover (not shown); Further, a push nut 12 for preventing slippage is installed adjacent to the bearing 7.

The movable rod portion 3 has a movable transmission shaft 13 therein.
The movable power transmission shaft 13 includes a rear portion 14 that is inserted into the main power transmission shaft 6, and a rear portion 14 that is inserted into the main power transmission shaft 6.
The front portion 15 is further forward in the axial direction and has an outer diameter smaller than the outer diameter of the rear portion 14. The front portion 15 of the movable power transmission shaft 13 is rotatably supported by a bearing 16 fixed inside the movable rod portion 3, and a push nut 17 for preventing it from coming off is attached adjacent to the bearing 16. ing. The outer peripheral surface of the rear portion 14 of the movable power transmission shaft 13 is supported by a one-way clutch 18 and a bearing 22 fixed inside the front end portion of the main power transmission shaft 6 so as to be slidable in the axial direction. The one-way clutch 18 transfers the rotational force of the main transmission shaft 6 in the direction driven by the prime mover to the movable transmission shaft 1.
However, if the prime mover suddenly stops or decelerates due to a failure or fuel shortage, the main power transmission shaft 6 side also suddenly stops or decelerates and receives a sudden inertial force. , In addition to this inertial force, the movable power transmission shaft 1, which had been rotating at high speed until then,
The inertial force on the third side is also added, and a very large inertial force is applied to the prime mover side. Therefore, in order to prevent such force from being transmitted to the joint between the main power transmission shaft 6 and the movable power transmission shaft 13, a one-way clutch is provided to immediately connect the joint between the main power transmission shaft 6 and the movable power transmission shaft 13. Automatically operates to release. Although various types of one-way clutches can be used as the one-way clutch 18, it is preferable that the outer cylinder of the one-way clutch is press-fitted onto the inner diameter of the main power transmission shaft 6, and that the clutch roller is attached to the rear portion 14 of the movable power transmission shaft 13. The clutch roller engages with the cam surface of the outer cylinder due to biased pressure of a spring that is slidably engaged with the outer peripheral surface and is disposed between the outer cylinder and the clutch roller, thereby reducing the rotational force of the main transmission shaft 6. is transmitted to the movable transmission shaft 13, and when rotating from the movable transmission shaft 13 side, the clutch roller separates from the cam surface of the outer cylinder to cut off transmission of rotational force between the main and movable transmission shafts 6 and 13. It is preferable that the

The large diameter rear portion 14 of the movable power transmission shaft 13 is
The operating rod 1 has a length L corresponding to a usable length range in which the operator can adjust the length of the operating rod 1 during normal work. Therefore, when the movable rod portion 3 is moved within a range corresponding to the normal usage length range of the operating rod 1,
The movable transmission shaft 13 remains drivingly connected to the main transmission shaft 6 via a one-way clutch 18. However, in order to reduce the length of the operating rod 1 to a storage length suitable for moving and storing the brush cutter, the movable rod portion 3 is moved further inward beyond the length L into the main rod portion 2 to a corresponding position. When the rear portion 14 of the movable transmission shaft 13 is moved to
is detached from the clutch roller of the one-way clutch 18, and the small diameter front portion 15 of the movable transmission shaft 13
are spaced apart from and facing the one-way clutch 18, thereby separating the connection between the main and movable transmission shafts 6 and 13 and cutting off the transmission of rotational force between them.

The movable rod portion 3 rotatably supports a movable blade drive member 20 at its front end portion, and the drive member 20 is connected to the front portion of the movable power transmission shaft 13 by a flexible power transmission shaft 21. 15.
When the movable rod portion 3 is in a position corresponding to the operating length range of the operating rod 1, the drive member 20 is configured to move from the prime mover to the flexible transmission shaft 9, the main transmission shaft 6, the one-way clutch 18, the movable transmission shaft 13, and the movable transmission shaft 13. The grass can be cut by being rotated in a predetermined direction by the driving force transmitted through the flexible transmission shaft 21. In addition, when the movable rod portion 3 is in the position shortened to the storage length of the operating rod 1, the main and movable transmission shafts 6 and 13
Since the connection between
0 is driven, the drive member 20 does not rotate, thereby preventing danger to the operator.

Effects of the Invention With the configuration of the present invention explained above, the present invention has the following effects:
The operating stick and power transmission shaft are tapered to a smooth shape to reduce the weight at the tip of the operating stick and the overall weight, improving operability and stably supporting the main power transmission shaft no matter where the movable parts are located. This prevents the occurrence of abnormal vibrations due to oscillation, and when it is at any position within the length range suitable for normal use,
The movable transmission shaft is drivingly connected to the main transmission shaft via a one-way clutch to maintain the power tool in operation, but when the operating rod is shortened to a length suitable for storage, etc., the movable transmission shaft is driven from the main transmission shaft. separated,
Therefore, even if the main transmission shaft is driven by the prime mover, the operating tool will not be driven, ensuring safety for workers, etc., and furthermore, the telescopic power transmission structure is simple and easy to manufacture. It has advantages such as being easy and inexpensive.

[Brief explanation of drawings]

The accompanying drawings are cross-sectional views schematically showing essential parts of embodiments of the present invention. 1... Operation stick, 2... Main stick part, 3... Movable stick part, 6... Main power transmission shaft, 13... Movable power transmission shaft, 1
4... Rear part of the movable power transmission shaft, 15... Front part of the movable power transmission shaft, 18... One-way clutch.

Claims (1)

[Claims] 1. In a working machine having an extendable operating rod in which a transmission shaft is supported through the inside, the operating rod 1 is provided with a main rod portion 2 and a movable rod portion 3 that can be moved in the axial direction in a telescoping manner with respect to the main rod portion. A hollow tubular main transmission shaft 6 is rotatably provided within the main rod portion, and is drivingly connected to the main transmission shaft via a one-way clutch 18 fixed inside the front end portion of the main transmission shaft. A movable transmission shaft 13 that can be moved in the axial direction in a telescoping manner with respect to the transmission shaft is rotatably provided within the movable rod portion, and the main transmission shaft 6 is mounted within the rear end portion 4 of the movable rod portion 3. The movable power transmission shaft is supported rotatably and relatively slidably in the axial direction by a bearing 8, and the front portion 15 of the movable power transmission shaft is formed to have an outer diameter smaller than the outer diameter of the rear portion 14 thereof. , a working machine characterized in that the rear portion 14 of the movable transmission shaft engages with the one-way clutch over an axial length range corresponding to the normal operating length of the operating stick 1.