JP2022175133A - Rotational power cut-off device of working power machine - Google Patents

Abstract

To provide a rotational power cut-off device of a working power machine, the device that has a function for restricting the rotation speed of an operation part of the working power machine so as not to exceed a predetermined rotation speed.SOLUTION: A rotational power cut-off device is constituted of: an input drum 20 having a cylindrical input drum circumferential wall 22 and an input drum bottom plate 24 for closing one end of the input drum circumferential wall 22; and an output drum 30 having clutch shoes 40 and 42 swingably provided inside of the input drum 20 and biased inside by springs 50 and 52, a cylindrical output drum circumferential wall 32 provided by aligning a rotation center with the input drum 20 so as to come in contact with the inside of the clutch shoes 40 and 42, and an output drum bottom plate 34 for closing one end of the output drum circumferential wall 32. The input drum bottom plate 24 is connected to an output shaft 60, and the output drum bottom plate 34 is connected to the drive shaft 70. When the rotation speed of the output shaft 60 becomes larger than a shutoff rotation speed (S), the clutch shoes 40 and 42 are made to deviate from the output drum 30 by the centrifugal force.SELECTED DRAWING: Figure 1

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary power cut-off device that cuts off transmission of rotary power generated by a prime mover of a working power machine to an operating part.

BACKGROUND ART Working power machines such as chain saws, power cutters, brush cutters, and trimmers having prime movers such as engines, electric motors, and air engines are widely used. These working power machines each have working parts such as chains, cutting blades, etc., which are driven by prime movers. In addition, since the working part is often located near the worker, there is a risk of injury due to contact between the working part and the worker or kickback during work. As a technique for reducing this risk, an invention (Patent Document 1) is disclosed in which the amount of fuel supplied to the prime mover at startup is controlled to control the number of revolutions of the prime mover to a threshold value or less.

Japanese Patent Publication No. 2017-538894

However, in the invention of Patent Literature 1, although the number of revolutions of the prime mover at the time of start-up is controlled to be equal to or less than a set threshold value, there is a problem that an abnormal increase in the number of revolutions during work cannot be dealt with.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a rotary power cutoff device for a power machine for work, which has a function of limiting the number of revolutions of the operating part of the power machine for work so that it does not exceed a predetermined number of revolutions.

In order to solve the above problems, a rotary power cutoff device for a power machine for work according to the present invention is provided between a prime mover and an operating part, and mechanically transmits power when the rotary power reaches a predetermined number of revolutions. The main feature is that it has a function of blocking

That is, the rotary power cut-off device for a power machine for work according to the first aspect of the present invention comprises an output shaft to which the rotary power of the prime mover of the power machine for work is transmitted, and the actuation part. A rotational power interrupting device provided between a driving shaft and an input drum having a cylindrical input drum peripheral wall and an input drum bottom plate closing one end of the input drum peripheral wall, and swingable inside the input drum. and a plurality of clutch shoes urged inwardly by springs, and a cylindrical output drum peripheral wall and output drum peripheral wall provided so as to be in contact with the inside of the plurality of clutch shoes and aligned with the rotation center of the input drum. and an output drum bottom plate closing one end thereof, the input drum bottom plate being linked to the output shaft, the output drum bottom plate being linked to the drive shaft, and the rotation speed of the output shaft being a predetermined breaking rotation speed (S ) above, the plurality of clutch shoes are separated from the output drum by centrifugal force.

According to the first aspect of the present invention, when the number of rotations of the output shaft reaches the cutoff number of rotations (S), the rotational power from the prime mover can be cut off to control the upper limit of the number of rotations of the operating section. . The rotary power cutoff device can be realized by reversing the structures of the input drum and the output drum of a general-purpose centrifugal clutch. The structure is such that the input drum covers the outer periphery of the output drum, a clutch shoe is provided on the input drum side so as to be swingable, and the clutch shoe is pressed against the output drum from the outside by a spring. When the number of revolutions of the output shaft, that is, the number of revolutions of the input drum, exceeds the cut-off number of revolutions (S) preset by the correlation between the pressing force of the spring and the mass of the clutch shoe, the centrifugal force overcomes the pressure of the spring. , the clutch shoe is separated from the output drum, thereby interrupting the transmission of rotational power to the drive shaft.

The cut-off speed (S) is set in consideration of safety according to the characteristics of the working power machine to which the rotary power cut-off device of the present invention is introduced. For example, if the working power machine is an engine-type brush cutter, the cut-off rotation speed is preferably about 10000 rpm. This is because if the number of rotations of the cutting blade exceeds 10,000 rpm, it becomes dangerous during work. In addition, the prime mover is an engine, an electric motor, an air engine, or anything that can generate rotational power.

A second aspect of the present invention is a chain saw, a power cutter, a pole saw, a brush cutter, a hedge trimmer, or a trimmer comprising the rotary power cutoff device of the first aspect of the present invention.

By equipping these working power machines with the rotary power cutoff device of the first invention, the safety of workers is improved.

A third aspect of the present invention is a chain saw, a power cutter, a pole saw, a brush cutter, a hedge trimmer, or a trimmer comprising a centrifugal clutch and the rotary power cut-off device of the first aspect of the invention between a prime mover and an operating part. is.

Equipping power machines for work with a universal centrifugal clutch in addition to the rotary power cutoff device further improves the safety of these machines during startup. Needless to say, the disengagement rotation speed (S) is greater than the engagement rotation speed (C) of the centrifugal clutch.

Further, the rotary power cutoff device of the fourth aspect of the present invention is the rotary power cutoff device of the first aspect of the present invention, which is mounted on the cutting blade rotating shaft at the tip of the brush cutter, wherein the input drum is fixed to the cutting blade rotating shaft, and the output drum is fixed to the cutting blade rotating shaft. is rotatably mounted on the cutting blade rotating shaft via a bearing provided at the tip of the cutting blade rotating shaft, and the output drum bottom plate has an opening in the center and a cutting blade holder to which the cutting blade is mounted. It is characterized by being

The rotary power cut-off device of the fourth aspect of the present invention has a structure in which the cutting blade of a conventional brush cutter is removed and then mounted on the cutting blade rotary shaft in place of the cutting blade. The input drum is fixed to the cutting blade rotating shaft and rotates together with the cutting blade rotating shaft. On the other hand, since the output drum is attached to the cutting-blade rotating shaft via a bearing provided on the cutting-blade rotating shaft, the rotational power of the cutting-blade rotating shaft is not directly transmitted to the output drum. A cutting blade holder to which a cutting blade is mounted is provided on the output drum bottom plate. The cutting blade holder consists of an upper holder, a cutting blade drive shaft erected at the center of the upper holder, and a lower holder and a nut for fixing the cutting blade after the cutting blade is mounted on the cutting blade drive shaft. The actions of the clutch shoe and the output drum are the same as those of the first invention.

The fifth aspect of the present invention is a bush cutter characterized by comprising a centrifugal clutch and the rotational power cutoff device of the fourth aspect of the present invention between a prime mover and an operating section.

By equipping the brush cutter with a general-purpose centrifugal clutch in addition to the rotary power cutoff device, the safety at the time of starting is further improved.

The rotary power cutoff device of the present invention improves the safety of working power machines.

1 is a cross-sectional view showing a first embodiment of the present invention; FIG. 1 is a plan view showing a first embodiment of the present invention; FIG. FIG. 4 is a cross-sectional view showing a second embodiment of the present invention; FIG. 3 is a cross-sectional view showing a third embodiment of the present invention; FIG. 10 is a cross-sectional view showing a fourth embodiment of the present invention; It is a plan perspective view showing a fourth embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a conceptual diagram which shows 1st embodiment of this invention. It is a conceptual diagram showing a second embodiment of the present invention.

Embodiments of the present invention will be described with reference to the drawings.
FIG. 7 is a conceptual diagram showing the first embodiment of the present invention.
A working power machine 10 is composed of a prime mover 2 , an output shaft 3 , a rotary power cutoff device 4 , a drive shaft 5 and an operating portion 6 . The rotational power of the prime mover 2 is transmitted to the output shaft 3, and the rotational power cutoff device 4 transmits the rotational power to the drive shaft 5 if the rotational speed of the output shaft 3 is less than the cutoff rotational speed (S). When the rotation speed of the output shaft 3 rises and reaches the cutoff rotation speed (S), the rotation power cutoff device 4 cuts off the transmission of the rotation power to the drive shaft 5, so that the operation part 6 stops operating after a while. .

After that, when the motor 2 is controlled and the rotational speed of the output shaft 3 becomes less than the cutoff rotational speed (S), the rotational power cutoff device 4 starts transmitting rotational power to the drive shaft 5 again, and the operating part 6 Resume operation.

FIG. 8 is a conceptual diagram showing a second embodiment of the present invention.
A working power machine 10 is configured by a combination of a prime mover 2 , an output shaft 3 , a centrifugal clutch 8 , a rotary power cutoff device 4 , a drive shaft 5 and an operating portion 6 . The centrifugal clutch 8 transmits the rotational power to the rotational power cutoff device 4 when the rotational speed of the output shaft 3 reaches the connection rotational speed (C). S) is reached, the rotary power is cut off.
There is a relationship of cut-off rotation speed (S)>connection rotation speed (C). to transmit rotational power to the operating portion 6, and the operating portion 6 starts rotating. Then, when the rotation speed of the output shaft 3 reaches the cutoff rotation speed (S), the rotation power cutoff device 4 cuts off the transmission of the rotation power to the drive shaft 5, and the operating part 6 starts to stop rotating. At this time, if the rotational speed of the output shaft 3 continues to be equal to or higher than the cut-off rotational speed (S), the rotational power will not be transmitted to the operating portion 6, and the operating portion 6 will eventually stop rotating.

If the rotation speed of the output shaft 3 becomes smaller than the cutoff rotation speed (S) before the operation portion 6 stops rotating, the rotational power is transmitted to the operation portion 6 again. S) Continue to rotate less than A worker who handles the working machine 10 in this way notices that the rotation speed has become excessive because the rotation speed of the operating part 6 suddenly decreases when the rotation speed is increased to the cut-off rotation speed (S) or more. In addition, accidents due to excessive rotation of the operating portion 6 can be prevented.

Next, examples of the present invention will be described below.

FIG. 1 is a cross-sectional view of the first embodiment of the present invention as seen from line AA in FIG. 2, and FIG. 2 is a plan view showing the first embodiment of the present invention. An input drum bottom plate 24 is fixed to the tip of the output shaft 60 , and an output drum peripheral wall 22 is erected on the outer circumference of the input drum bottom plate 24 . Clutch shoes 40 and 42 are attached to the input drum bottom plate 24 with bolts 62 and 64 so as to be swingable. Clutch shoes 40 and 42 are respectively pressed toward the center by springs 50 and 52 attached to the inner surface of input drum peripheral wall 22 , and lining 44 of clutch shoe 40 and lining 46 of clutch shoe 42 are in contact with output drum peripheral wall 32 . there is

On the other hand, the output drum 30 is composed of an output drum bottom plate 34 and an output drum peripheral wall 32 erected therearound. A drive shaft 70 is fixed to the output drum bottom plate 34 .

Here, when the rotation speed of the output shaft 60 increases and reaches the cut-off rotation speed (S), the centrifugal force acting on the clutch shoes 40 and 42 overcomes the pressing force of the springs 50 and 52, and the clutch shoes 40 and 42 are released. move outward to move the linings 44 and 46 away from the output drum peripheral wall 32 . This operation cuts off the transmission of the rotational power of the output shaft 60 to the drive shaft 70, and eventually the drive shaft 70 stops rotating.

After that, when the rotation speed of the output shaft 60 decreases and becomes smaller than the cut-off rotation speed (S), the pressing force of the springs 50 and 52 overcomes the centrifugal force, and the linings 44 and 46 come into contact with the output drum peripheral wall 32, The drive shaft begins to rotate again. Note that the shutoff rotation speed (S) is adjusted by the mass of the clutch shoes 40 and 42 and the pressing force of the springs 50 and 52 .

FIG. 3 is a sectional view showing a second embodiment of the present invention, showing the vicinity of the prime mover 108 of the bush cutter 200. As shown in FIG. The vertical motion of the prime mover 108 is converted into rotational motion by the crankcase 112 to rotate the crankshaft (output shaft) 114 . A flywheel 116 is provided at the tip of the crankshaft (output shaft) 114 , and a centrifugal clutch 118 is fixed to the flywheel 116 . A centrifugal clutch drum 140 is rotatably provided via a connecting shaft 144 and bearings 130 and 132 .

Further, a rotary power cutoff device 206 is joined to the centrifugal clutch drum 140 via the input drum 136 . Since the structure of the rotary power cutoff device 206 is as described above, the description thereof is omitted. A drive shaft 146 is fixed to the output drum 142 of the rotary power cutoff device 206 , and a connecting shaft 144 is rotatably supported inside the output drum 142 via bearings 132 .

When the crankshaft (output shaft) 114 rotates and the number of revolutions reaches the connection number of revolutions (C), the centrifugal force operates the centrifugal clutch 118 to rotate the centrifugal clutch drum 140, and the input drum integrated therewith. 136 rotates similarly. At this time, since the rotary power cutoff device 206 transmits the rotary power to the output drum 142, the drive shaft 146 also rotates.

When the rotation speed of the crankshaft (output shaft) 114 increases and reaches the cutoff rotation speed (S), the rotational power cutoff device 206 cuts off transmission of the rotational power of the crankshaft (output shaft) 114 to the drive shaft 146. do.

FIG. 4 is a cross-sectional view showing a third embodiment of the present invention, showing the vicinity of an engine (prime mover) 310 of a chain saw 300. As shown in FIG. A centrifugal clutch 350 is attached to the tip of a crankshaft (output shaft) 320 that is rotationally driven by an engine (prime mover) 310 . A description of the structure of centrifugal clutch 350 is omitted. The centrifugal clutch drum 352 on the output side of the centrifugal clutch 350 is connected to the input drum 332 of the rotary power cutoff device 330 , and both are rotatably mounted on the crankshaft (output shaft) 320 via bearings 342 .

A sprocket (drive shaft) 360 that drives a saw chain 370 is connected to the output drum 334 . A detailed description of the operation of the centrifugal clutch 350 and the rotary power cutoff device 330 is omitted because it is the same as that of the second embodiment. The transmission of rotational power to shaft 360 is interrupted.

FIG. 5 is a sectional view showing a fourth embodiment of the present invention, showing the vicinity of the cutting blade 210 of the brush cutter 200. As shown in FIG. FIG. 6 is a perspective plan view of the fourth embodiment of the present invention as seen from line BB in FIG. Unlike the second embodiment, a rotational power cutoff device 206 is provided between the bevel gear 272 and the cutting blade 210 . A bevel gear 270 provided at the tip of a transmission shaft 248 connected to the prime mover engages with a bevel gear 272 provided at the starting end of a cutting blade rotating shaft (output shaft) 276 . An input drum holder 292 is provided around the cutting blade rotating shaft (output shaft) 276 , and an input drum 260 is joined to the lower side of the input drum holder 292 . A clutch shoe 268 is provided inside the input drum 260 so as to be swingable around a clutch shoe mounting hole 284 . A clutch shoe 268 abuts the output drum 266 . The output drum 266 is rotatably mounted on the cutting blade rotation shaft (output shaft) 276 via a bearing 258 fixed to the cutting blade rotation shaft (output shaft) 276 with a nut 283. output shaft 276. A cutting blade holder 288 is provided on the lower surface of the output drum 266 . The cutting blade holder 288 is composed of an upper holder 290 fixed to the output drum 266 with bolts and nuts 280, a cutting blade drive shaft (drive shaft) 274 projecting from the upper holder 290, a lower holder 291, and a nut 282. Blade 210 is sandwiched between upper holder 290 and lower holder 291 and fixed by nut 282 .

When the rotation speed of the cutting blade rotation shaft (output shaft) 276 reaches the cut-off rotation speed (S), centrifugal force spreads the clutch shoe 268 outward and separates it from the output drum 266, and the cutting blade 210 begins to stop rotating. When the rotation speed of the cutting blade rotating shaft (output shaft) 276 becomes smaller than the cut-off rotation speed (S) before the rotation of the cutting blade 210 stops, the clutch shoe 268 comes into contact with the output drum 266 again, Rotational power is transmitted.

2 Prime mover 3 Output shaft 4 Rotational power cutoff device 5 Drive shaft
6 Actuating Part 8 Centrifugal Clutch 10 Working Power Machine 20 Input Drum 22 Input Drum Peripheral Wall 24 Input Drum Bottom Plate 30 Output Drum 32 Output Drum Peripheral Wall 34 Output Drum Bottom Plate 40 Clutch Shoe 42 Clutch Shoe 44 Lining 46 Lining 50 Spring 52 Spring 54 Spring Seat 55 Spring seat 56 Spring seat 57 Spring seat 60 Output shaft 62 Bolt 64 Bolt 70 Drive shaft 108 Engine 112 Crankcase 114 Crankshaft (output shaft)
116 flywheel 118 centrifugal clutch 130 bearing 132 bearing 134 bearing 136 input drum 140 centrifugal clutch drum 142 output drum 144 connecting shaft (output shaft)
146 Drive shaft 200 Brush cutter 206 Rotational power cutoff device 210 Cutting blade 248 Transmission shaft 250 Bearing 252 Bearing 254 Bearing 258 Bearing 260 Input drum 266 Output drum 268 Clutch shoe 270 Bevel gear 272 Bevel gear 274 Cutting blade drive shaft (drive shaft)
276 cutting blade rotating shaft (output shaft)
280 bolt/nut 282 nut 283 nut 284 clutch shoe mounting bolt 288 cutting blade holder 290 upper holder 291 lower holder 292 input drum holder 300 chain saw 310 engine (motor)
320 crankshaft (output shaft)
330 rotational power cutoff device 342 bearing 344 bearing 350 centrifugal clutch 360 sprocket (drive shaft)
370 Saw chain S Breaking rotation speed C Connection rotation speed

Further, the rotational power cutoff device of the fourth aspect of the present invention is the rotational power cutoff device of the first aspect of the present invention, wherein the bottom plate of the output drum has an opening at the center, the output shaft is inserted into the opening, and the output A bearing is provided at the tip of the shaft, and the output drum is rotatably provided on the output shaft via the bearing .

In the rotary power cutoff device of the fourth aspect of the present invention, the output drum is attached to the output shaft via bearings . Therefore, the rotational power of the output shaft is not directly transmitted to the output drum. The actions of the clutch shoe and the output drum are the same as those of the first invention.

A fifth aspect of the present invention comprises the rotary power cutoff device according to claim 4, a centrifugal clutch provided on the output shaft, and a cutting blade holder provided on the output drum, wherein the centrifugal clutch connects the prime mover and the operating part. and wherein the output shaft is a cutting blade rotating shaft .

A brush cutter according to the fifth aspect of the present invention has a structure in which the rotating power cutoff device according to the fourth aspect of the present invention is mounted in place of the cutting blade after removing the cutting blade from the cutting blade rotating shaft of the conventional brush cutter. , the cutting blade rotary shaft serves as the output shaft of the rotary power cutoff device. The input drum is fixed to the cutting blade rotating shaft and rotates together with the cutting blade rotating shaft. A cutting blade holder is provided on the output drum. The cutting blade holder consists of an upper holder, a cutting blade drive shaft erected at the center of the upper holder, and a lower holder and a nut for fixing the cutting blade after the cutting blade is mounted on the cutting blade drive shaft. By equipping the brush cutter with a general-purpose centrifugal clutch in addition to the rotary power cutoff device, the safety at the time of starting is further improved.

Claims (5)

A rotary power cutoff device provided between an output shaft to which the rotary power of the prime mover is transmitted and a drive shaft for driving the actuation part of a working power machine having an operating part operated by the rotary power of the prime mover,
an input drum having a cylindrical input drum peripheral wall and an input drum bottom plate that closes one end of the input drum peripheral wall; and a plurality of clutch shoes provided swingably inside the input drum and biased inward by a spring. An output drum having a cylindrical output drum peripheral wall provided so as to be in contact with the inner side of the plurality of clutch shoes so as to coincide with the rotation center of the input drum, and an output drum bottom plate closing one end of the output drum peripheral wall. is,
When the input drum bottom plate is linked to the output shaft, the output drum bottom plate is linked to the drive shaft, and the number of rotations of the output shaft reaches or exceeds a predetermined shutoff number of rotations (S), the plurality of clutch shoes are separated by centrifugal force. A rotary power cutoff device, wherein the device is separated from the output drum. A chain saw, a power cutter, a pole saw, a bush cutter, a hedge trimmer or a trimmer comprising the rotary power cutoff device according to claim 1. A chain saw, a power cutter, a pole saw, a bush cutter, a hedge trimmer, or a trimmer comprising a centrifugal clutch and the rotary power cutoff device according to claim 1 between the prime mover and the operating portion. 2. The rotational power cutoff device according to claim 1, which is attached to the cutting blade rotating shaft at the tip of the brush cutter,
The input drum is fixed to the rotating shaft of the cutting blade, the output drum is rotatably mounted on the rotating shaft of the cutting blade through a bearing provided at the tip of the rotating shaft of the cutting blade, and the bottom plate of the output drum is opened at the center. A rotary power shut-off device, comprising: a cutting blade holder having a portion and to which a cutting blade is mounted. A bush cutter, comprising a centrifugal clutch and the rotary power cutoff device according to claim 4 between the prime mover and the operating portion.

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