JPH0724018Y2 - Brush cutter - Google Patents

Description

TECHNICAL FIELD The present invention relates to a brush cutter.

2. Description of the Related Art A brush cutter is equipped with a cutting blade at the front end of an elongated operating rod, and an internal combustion engine is installed at the rear end of the operating rod, and power from the internal combustion engine is cut through an electric shaft arranged inside the operating rod. It is transmitted to the blade to rotate the blade to perform mowing work.
In this case, in the conventional brush cutter, when the mowing work is stopped, the engine speed is reduced to the idling speed to release the clutch between the crankshaft and the electric shaft of the internal combustion engine.
The brush blade continues to rotate by inertial force as it is, which is very dangerous for workers.

SUMMARY OF THE INVENTIONTherefore, according to the present invention, when the engine speed falls below the idling speed, the brake device automatically operates to rapidly stop the cutting blade and protect the safety of workers. An object of the present invention is to provide a brush cutter having a simple structure and which can be manufactured at low cost.

Means for Solving the Problems A brush cutter according to the present invention includes a braking device at a portion of an engine case adjacent to a driven side member of a clutch connected to a crankshaft of an internal combustion engine attached to a rear end portion of an operating rod. Is provided, the brake device is pressed by a spring so as to be in sliding contact with the driven side member of the clutch, and the brake control wire of the brake device is connected to the throttle lever provided on the operating rod side and the internal combustion engine side. At a middle portion of a throttle control wire for connecting with a throttle valve disposed on the control rod side, and is detachable via a joint member slidably guided in a longitudinal direction in a guide frame fixed to the operation rod side. It is characterized in that the brake device is connected and the brake device is released and the braking operation is directly performed in conjunction with the opening / closing operation of the throttle valve by the operation of the throttle lever.

Therefore, by releasing the brake device by pulling down the throttle lever, at the same time opening the throttle valve, accelerating the engine to rotationally drive the cutting blade, and releasing the throttle lever. At the same time that the engine speed is reduced to the idling speed, the brake device is simultaneously braked to make sliding contact with the driven side member of the clutch, thereby rapidly stopping the rotation of the brush blade.

Embodiment Next, the present invention will be described based on an embodiment of the drawings.

First, in the embodiment shown in FIG. 1, an internal combustion engine 2 is inserted into an engine case 1 formed of a suitable material such as synthetic resin, and the internal combustion engine 2 is of a two-cycle type in this embodiment. The engine is a cylinder 4 in which a piston 3 is reciprocally movable, and a crankcase 5 is provided continuously from the cylinder 4.
The crankcase 5 has a crankshaft 6 and a bearing 7
And 8 are rotatably supported, and the piston 3 and the crankshaft 6 are connected by a connecting rod 9. A normal type recoil type starter 10 is provided at a rear end of the engine case 1 coaxially with a rear end of a crankshaft 6 extending rearward from the crankcase 5 to operate the starter 10. Thus, the crankshaft 6 can be rotated to start the internal combustion engine 2.

The front end of the crankshaft 6 extends forward from the crankcase 5 in the engine case 1 and has a cooling fan 11 and a centrifugal clutch 12 attached thereto. A front cover 13 is attached to the front surface of the engine case 1 by screws or the like.
It is covered by. The front cover 13 is formed of an appropriate material such as synthetic resin and constitutes a part of the engine case 1. The cooling fan 11 is provided in the engine case 1
External air is sucked into the engine case 1 from an intake port 14 formed at the bottom of the cylinder, and the sucked air is blown to the cylinder 4 of the internal combustion engine 2 as cooling air to cool the cylinder 4.

The centrifugal clutch 12 is a clutch boss 15 as a driving side member fixed to the front end portion of the crank shaft 6, and a driven member which is supported by the crank shaft 6 via a bearing 16 and is arranged concentrically with the clutch boss 15. The bearing 16 supports the clutch drum 17 so as to be rotatable independently of the crankshaft 6. The clutch boss 15 has a plurality of clutches 18 pivotally supported therein, and each clutch 18 is operated by centrifugal force when the crankshaft 6 rotates at a predetermined speed higher than the idling speed of the engine 1. And pivots radially outward to frictionally engage the inner peripheral surface of the clutch drum 17, and the rotational driving force of the crankshaft 6 is transmitted from the clutch boss 15 to the clutch drum 17 to rotate the clutch drum. To work.

The front cover 13 is integrally formed with a mounting portion 19 projecting forward, and the rear end portion of the operating rod of a brush cutter (not shown) is inserted into the mounting portion 19 and fixed by screws or the like. It
At this time, the rear end of an electric shaft (not shown) rotatably arranged in the operating rod is fitted and mounted in a mounting hole 20 integrally formed in the front portion of the clutch drum 17, and the transmission shaft is attached. Is rotated together with the clutch drum 17 to transmit its rotational force to a mowing blade (not shown) provided at the front end of the operating rod, thereby rotating the mowing blade to perform mowing work. .

The front cover 13 is provided with a brake device 22 in an axial inner hole 21 formed in the mounting portion 19, and the brake device 22 is slidably guided in the inner hole 21 in the axial direction. It has a supported brake member 23 and a brake shoe 24 attached to the tip of the brake member 23. The brake shoe 24 is arranged so as to be capable of sliding contact with the outer end surface of the clutch drum 17 of the centrifugal clutch 12. Furthermore,
Inside the inner hole 21, the inner end and the brake member 23
A compression coil spring 25 acting between and is arranged, the compression coil spring 25 presses the brake member 23 outward,
The brake shoe 24 is brought into sliding contact with the end surface of the clutch drum 17, and the clutch drum 17 is held so as not to easily rotate.

One end of a flexible pulling wire 26 is attached to the brake member 23, and the pulling wire 26 extends forward in the internal hole 21 of the attaching portion 19 of the front cover 13 and further penetrates the attaching portion 19. It extends to the outside. Further, the pulling wire 26 extends through a flexible protection tube 27 attached to the outside of the attachment portion 19 of the front cover 13 to an operation handle of an operation rod (not shown).

In the operating handle of the operating rod, the pulling wire 26 is connected to one end of an elongated joint member 28. The joint member 28
Is guided and supported in a guide frame 29 fixed to the operation handle so as to be slidable in the longitudinal direction. Further, the joint member 28
Another flexible pulling wire 30 extending from a throttle valve of a carburetor (not shown) of the internal combustion engine 2 is connected to the one end of the inside of another flexible protection tube 31. The joint member 28 has another pulling wire 32 connected to the other end thereof, and the pulling wire 32 passes through a further flexible protective tube 33 attached to the guide frame 29 and is pivoted to an operating handle. It is connected to a throttle lever (not shown) that is movably provided.

With such a configuration, when performing the mowing work, when the worker pivots the throttle lever of the operation handle of the brush cutter so as to squeeze, the brake device 22 causes the pulling wire 26 to move.
Thus, the brake shoe 24 is moved against the action of the compression coil spring 25 to enter the releasing operation, and the brake shoe 24 is separated from the clutch drum 17 of the centrifugal clutch 12. At the same time, the throttle valve of the carburetor of the internal combustion engine 2 is pivoted through the pull wire 30 to open, thereby accelerating the engine speed above the idling speed and increasing the rotational speed of the crankshaft 6. Therefore, the clutch clutch 18 of the centrifugal clutch 12 is brought into sliding contact with the inner peripheral surface of the clutch drum 17 by the action of the centrifugal force acting on the clutch clutch 18, and rotationally drives the clutch drum 17, and this driving force is transmitted through the transmission shaft in the operating rod. It is transmitted to the brush blade and the brush blade can be rotated to perform grass cutting work. When the throttle lever is released when the mowing operation is stopped or finished, the throttle valve of the carburetor is closed to decelerate the internal combustion engine 2 to the idling speed, and at the same time, the brake device 22 causes the compression coil spring.
By the action of 25, the brake shoe 24 is moved to the original position so that the brake shoe 24 is brought into sliding contact with the clutch drum 17, and the braking operation is started. Therefore, the clutch drum 17, the electric shaft and the cutting blade are rapidly braked by the inertial force to further rotate and immediately stop.

Next, in another embodiment of the present invention shown in FIG. 3, the internal hole 21 for guiding and supporting the brake member 23 of the brake device 22 is a portion of the engine case 1 close to the outer peripheral surface of the clutch drum 17 of the centrifugal clutch 12. Is formed so as to extend outward in the radial direction, the brake device 22 is movably arranged in the inner hole 21 in the radial direction of the clutch drum 17, and the brake coil 22 of the compression coil spring 25 arranged in the inner hole 21 is formed. Due to the action, the brake shoe 24 at the tip of the brake member 23 is brought into sliding contact with the outer peripheral surface of the clutch drum 17 to perform a braking operation.
The structure of the other parts of this embodiment is the same as the structure of the corresponding parts of the embodiment of FIGS.

Effect of the Invention With the configuration of the present invention described above, the present invention has a simple and reliable configuration in which the intermediate portion of the throttle control wire is connected via a joint member, which not only widens the flexibility of the airframe layout but also allows the slot lever Just by operating, the brake device was released and braked by directly interlocking with the opening / closing operation of the slottle valve by operating the slottle lever, so the engine was accelerated to rotationally drive the bush cutter, and also the slottle lever was released. This reduces the engine speed to the idling speed and simultaneously brakes the brake device to bring it into sliding contact with the driven side member of the clutch, thereby rapidly stopping the rotation of the bush cutter and protecting the safety of workers. Moreover, since the brake device has a simple structure and is arranged in the engine case, the number of parts is small and the brake device can be manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing an embodiment of the brush cutter according to the present invention, FIG. 2 is a partially cutaway view of a wire joint, and FIG. 3 is a sectional view of an essential part of another embodiment of the present invention. Is. 1 ... Engine case, 2 ... Internal combustion engine, 6 ... Crankshaft, 12 ... Clutch, 22 ... Brake device, 25 ... Spring, 26 ... Wire.

Claims (1)

[Scope of utility model registration request] 1. A clutch (12) connected to a crankshaft (6) of an internal combustion engine (2) attached to a rear end portion of an operating rod.
Of the engine case (1, 13) close to the driven side member (17) of the engine is provided with a brake device (22) so that the brake device can reciprocate, and the spring (25) is slidably contacted with the driven side member of the clutch. ), And connects the brake control wire (26) of the brake device to the throttle lever arranged on the operating rod side and the throttle valve arranged on the internal combustion engine side (30). The throttle lever is connected in a removable manner via a joint member (28) slidably supported in the longitudinal direction in a guide frame (29) fixed to the operation rod side at an intermediate portion of the throttle lever. The brush cutter is characterized in that the brake device is released and the braking operation is performed by directly interlocking with the opening / closing operation of the throttle valve.