JPH0220864B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a backpack-type working machine, and more specifically, it utilizes shaft output generated from an engine-driven prime mover supported by a backpack frame to carry out desired work, such as rotating a rotary blade. The present invention relates to a working machine that is configured to perform mowing and branch removal work performed by using a handwheel, or felling work performed by driving a chain saw.

One of the important factors in determining whether or not such a working machine is of practical use is whether the transmission of vibrations from the prime mover to the backpack frame is sufficiently damped. If this vibration damping is insufficient, the strong vibrations generated by the prime mover that rotates at 8,000 to 10,000 revolutions per minute will be transmitted from the backpack frame to the shoulders and back of the worker, and the worker will quickly feel pain from this vibration, resulting in a long-lasting life. Unable to withstand hours of continuous work.

In a reciprocating internal combustion engine (hereinafter referred to as an engine), which is an example of a prime mover, vertical vibrations caused by alternating changes in the acceleration of a piston that reciprocates up and down in a cylinder, and a balance weight fixed to a crankshaft. An extremely complex vibration is generated, which is a combination of vertical and lateral vibrations caused by the rotation of the engine, and lateral vibrations caused by the side thrust during the explosion stroke.
In particular, a single-cylinder two-stroke engine, which has the simplest structure and is the cheapest, is used as the power source for backpack-type work equipment, and with such an engine, all that is needed is a balance weight fixed to the crankshaft as described above. The vibrations generated are intense because they cannot be removed sufficiently. In this way, the engine can be said to be a source that generates power for work and at the same time a vibrating body that generates intense vibrations. Therefore, for example, in the case of an automobile engine, in order to prevent engine vibrations from being directly transmitted to members supporting the engine, such as the chassis frame, vibration insulation such as rubber is used between the engine and supporting members. It is common practice to intervene with the body, and this has been somewhat effective.

In the field of backpack-type work equipment, anti-vibration measures have been taken to prevent engine vibrations from being transmitted to the backpack frame, and a representative example is Utility Model Application Publication No. 53-138929. There are some published in the official gazette. This device has a structure in which a support plate attached to the lower part of the engine and a support plate fixed to the backpack frame face each other, and a vibration isolating rubber is interposed between these support plates as a vibration insulator. That is, this anti-vibration support structure is basically the same as the anti-vibration support structure in the above-mentioned automobile engine.

However, even if the above-described vibration-proof support structure is adopted in the field of backpack-type working machines, its effectiveness has not increased much in practice. The present inventor discovered that the reason lies in the following points.

The first reason is that rubber has deformation resistance due to its viscosity, so when the frequency of vibration increases, it cannot deform to follow the vibration, and therefore most of the engine vibration is transferred to the backpack frame. It means that it gets passed on. In particular, in the anti-vibration support structure shown in the above publication, the rubber itself needs to support the weight of the engine, so in consideration of its lifespan, it is necessary to use a certain degree of hard rubber as the rubber. Therefore, the above-mentioned tendency becomes stronger.

The second reason is that in backpack-type work machines, the weight of the backpack frame that supports the engine is extremely small (up to 0.5Kg) compared to the weight of the engine (4Kg to 6Kg) that is the vibrating body. , the rubber interposed between the engine and the backpack frame is not an insulator that prevents engine vibrations from being transmitted to the backpack frame, but rather because the vibration of the heavy vibrating body excites the light backpack frame. This means that it will only function as a connecting member. The above-mentioned anti-vibration support structure in which rubber serving as a vibration insulator is interposed between the vibrating body and the support body is suitable for use when supporting an engine while taking anti-vibration measures against the body of a car. It becomes effective only when the weight of the support is sufficiently large compared to the weight of the vibrating body.
In other words, it can be said that the conventional vibration isolation support structure as described above has been developed as a structure for supporting a vibrating body on a sufficiently heavy support.

As mentioned above, even if the anti-vibration support structure that has been commonly adopted for automobile engines is adopted as the anti-vibration support structure for the engine backpack frame of a backpack-type work machine, a significant anti-vibration effect can be expected. It is clear that it cannot be done.

The present invention was devised under the above circumstances, and is capable of significantly damping the vibrations transmitted from the engine to the backpack frame that supports it, and is sufficient for long-term continuous work. The purpose of the present invention is to provide a backpack-type working machine configured to withstand extreme conditions.

In order to achieve this objective, the present invention takes the following technical measures.

That is, the backpack-type work machine of the present invention is capable of carrying out backpack-type work in which the engine that drives the work machine is mounted on a backpack frame having a horizontal part and a back support part extending upward from the front end of the horizontal part, on the horizontal part. In the aircraft, an elastic body having a central horizontal part and at least three legs extending radially from the central horizontal part is interposed between the engine and the horizontal part, and the elastic body The lower part of the engine is attached to the central horizontal part, and each of the legs is allowed a predetermined amount of play in the direction perpendicular to the direction in which each leg extends and in the direction in which each leg extends with respect to the horizontal part. At the same time, it is characterized in that the engine is supported on the horizontal portion by being restrained and supported so that it cannot be removed upwardly.

That is, in the present invention, in the vibration-proof support structure provided in the conventional backpack-type work machine, one end of the rubber serving as the elastic body is attached to the engine or a member integral therewith, and the other end is attached to the backpack frame serving as the support. Since the two ends of the rubber are fixed, the forced vibration acting on one end of the rubber will be slightly alleviated by the time it reaches the other end of the rubber. Focusing on the fact that the vibration is transmitted to the backpack frame, we installed an elastic body made of metal or resin as a vibration insulator between the horizontal part of the backpack frame and the engine mounted on this horizontal part.
The lower part of the engine is supported by the elastic body, and each leg of the elastic body is not fixed to the backpack frame, but can be moved relative to the horizontal part by a predetermined amount in the horizontal or vertical direction. He gave them full support. Therefore, in the backpack-type working machine of the present invention, the lateral (horizontal) component of engine vibration is not transmitted to the backpack frame at all. Regarding the longitudinal (vertical) component of engine vibration, the elastic body
An elastic body made of metal or resin that instantly follows engine vibrations and instantly bends and deforms, and its legs move slightly in the horizontal direction relative to the horizontal part of the backpack frame. Since the vibrations of the legs are no longer directly transmitted to the backpack frame, this vertical component is significantly attenuated.

Therefore, in the backpack-type work machine of the present invention, only the significantly attenuated longitudinal component of the engine vibration is transmitted to the backpack frame, so the overall vibration-proofing effect is as follows: It is much superior to conventional backpack-type work machines. In addition, the longitudinal component of the engine vibration transmitted to the backpack frame should be small enough to be easily removed by the backrest of the backpack frame or a vibration-proof pad attached to the shoulder belt. As a result, the worker can continue working without feeling the vibrations of the engine on the backpack frame.

The embodiments of the present invention will now be described in detail with reference to the drawings. Note that the drawings show an example in which the present invention is applied to a backpack-type power brush cutter.

FIG. 1 shows the overall configuration of a backpack-type power brush cutter to which the present invention is applied. This brush cutter has a shoulder strap 1
An engine 3 serving as a power source is placed on a backpack frame 2 equipped with A rotary blade 6 attached to the tip of the blade 5 is rotated. The back frame 2 is formed by bending and welding a lightweight metal pipe, for example, and has a horizontal part 2a on which the engine 3 is placed and a vertical back rest part 2b to which the back rest pad 7 is attached. have. The shoulder band 1 is composed of a pair of left and right flexible belts, etc., with one end attached to the top of the back rest part 2a and the other end attached to the lower part, and a shoulder rest pad 8 is attached to the middle part. There is. The worker carries this backpack frame 2 on his back via the shoulder band 1,
an operating grip 9 attached to an appropriate portion of the operating tube 5;
9 and swinging the operating tube 5 to perform brush cutting work.

2 and 3 show in detail the support structure for supporting the engine 3 on the horizontal portion 2a of the backpack frame 2. The engine 3 is supported via an elastic body 10 formed in a special shape. This elastic body 10
is made of bendable metal or resin. In this embodiment, the elastic body 10 has a starfish-shaped planar shape with legs 10b, 10b, . . . extending in all directions from a central horizontal engine mounting portion 10a, as shown in FIG. In addition, each of the leg portions 10
b, 10b, . . . extend diagonally downward from the engine mounting portion 10a, and then are bent so that their tips extend approximately horizontally, and as a whole, this elastic body 1
0 has a flat isosceles trapezoid shape when viewed from the front.

An engine 3 is attached to the engine attachment portion 10a so as to be rotatable around a vertical axis. For this purpose, for example, the vertical support shaft 11 protruding from the lower surface of the engine 3 may be supported by the engine mounting portion 10a via bearings b, b. When the engine 3 is supported on the backpack frame 2 so as to be rotatable around the vertical axis in this way, the operating tube 5 can be swung while being expanded and contracted as shown by arrows P and Q in FIG. This is advantageous because it makes mowing extremely easy and increases the area that can be mowed while standing in a certain position.

On the other hand, each leg portion 10b, 10b of the elastic body 10...
As shown in FIG. 3, elongated holes 12, 12, . Screw shafts 14, 14 . . . project upward from planar sliding plates 13, 13 fixed to 2a so as to substantially correspond to the positions of the respective elongated holes 12.
The long holes 12, 12... are fitted into.... It is preferable that the outer diameter of the screw shafts 14, 14... be set to be smaller than the width of the elongated holes 12, 12.... The screw shafts 14, 14... insert bolts from below into holes provided in the sliding plates 13, 13...
It can be easily formed by welding to the back surfaces of 3 and 13. Further, as clearly shown in Fig. 2, after fitting the long holes 12, 12... of the leg portions 10b, 10b into the screw shafts 14, 14..., screw the double lock nuts 15, 15... attached, the leg portion 10b,
10b are arranged so that they do not separate from their respective predetermined positions.

Thus, the elastic body 1 carrying the engine 3
0, the elongated hole 12 of the horizontal end portion 10c of each leg portion 10b is loosely fitted into the screw shaft 14 of the sliding plate 13 fixed to the horizontal portion 2a of the backpack frame 2.
It becomes possible to freely move a certain distance in the horizontal direction, and the central engine mounting part 10a
can be elastically deformed to sink in the vertical direction. That is, since the width of the elongated hole 12 is set to be larger than the outer diameter of the screw shaft 14, the elastic body 10 as a whole has some freedom of distance not only in the direction of arrows A and B in FIG. 3, but also in the direction of C and D. On the other hand, when the central engine mounting part 10a sinks, each leg part 10
b, 10b, . . . are simultaneously able to move slightly outward about the vertical support shaft 11.

Now, in the backpack-type work machine of this example configured as described above, vibrations transmitted from the engine to the backpack frame are significantly attenuated.

That is, as described above, the complex vibrations caused by the rotation of the engine can be divided into a horizontal component and a vertical component. In the backpack-type working machine of this example, the legs 10b of the elastic body 10 supporting the engine are supported so as to be freely slidable in the horizontal direction on the sliding surface formed on the backpack frame, as described above. Therefore, even if the elastic body is vibrated in the horizontal direction due to the horizontal component of engine vibration as shown in FIG. 4, the vibration will not be transmitted to the sliding plates 13, 13 or the backpack frame 2. . In addition, due to the vertical component of engine vibration, the engine mounting portion 10a of the elastic body 10
Even if the elastic body 10 is caused to vibrate in the vertical direction, the elastic body 10 immediately follows the vibrations of the engine, as shown by the imaginary line in FIG. Since 10c is elastically deformed so as to escape slightly outward in the horizontal direction, direct transmission of the vertical component of engine vibration to the sliding plate 13 or the backpack frame 2 can be avoided. As a result, only a small portion of the vertical component of the vibration of the engine 3 is transmitted to the backpack frame 2, and its vibration damping effect is different from that of the engine and backpack that have been conventionally adopted in this type of backpack-type work machine. This is dramatically improved compared to a vibration-proof support structure that uses rubber as a vibration insulator between the frame and the frame. This effect is due to the use of an elastic body made of metal or resin as a vibration insulator, which does not have deformation resistance like rubber, but can bend and deform instantly following the excitation force, and the elastic body. This was achieved for the first time by adopting a new configuration that had never been seen before, basically cutting off direct communication between the end and the backpack frame. Incidentally, it is obvious that if the ends (legs) of the elastic body of the present invention are fixed to the backpack frame, the backpack frame will be forced to vibrate due to the vibration of the legs caused by engine vibration. . Also, conventionally,
There are vibration insulators that use coil springs instead of rubber, but in this case, the phase of the vibration at one end of the coil spring is out of phase with the phase at the other end.
In addition, the free vibration frequency of the coil spring itself may match the vibration frequency of the engine, causing unexpected resonance, and it has not always been possible to achieve an appropriate vibration-proofing effect. The legs have a large free vibration frequency that rarely matches the engine's vibration frequency, and unlike coil springs, the vibration propagation speed is slow and there is no possibility that the vibrations at both ends will be out of phase. It is also possible to solve the disadvantages of using a coil spring.

In the present invention, the measures for supporting the legs of the elastic body so as to be movable relative to the horizontal portion of the backpack frame in the horizontal direction or in the vertical direction are not limited to those in the embodiments shown in FIGS. 1 to 5. . That is, as shown in FIG. 6, for example, a gate-shaped holding frame 16 is formed on the sliding surface, and the tips 10c of each leg portion 10b of the elastic body 10 are disposed within this holding frame 16.
It is sufficient to simply allow the passage to freely move. Further, the tip end 10c of the leg portion 10b does not need to be horizontal, and may be bent into an arc shape as shown in FIG. In this way, the sliding surface 1
3, the frictional resistance during sliding also becomes smaller, which leads to an increase in the vibration-proofing effect. In this case, as shown in FIG. 8, it is convenient to form a holding frame 16 surrounding the leg portion 10b so that the leg portion 10b does not separate from the sliding surface 13. Furthermore, as shown in FIG.
This is advantageous because it does not shift more than necessary with respect to the horizontal portion 2a.

Further, the leg portions 10b of the elastic body 10 do not need to be inclined diagonally downward as shown in FIGS. 1 to 8, but may be made to extend horizontally as shown in FIG. good. Even in this case, if the ends of the legs are supported so that they can freely slide in the horizontal direction, vibrations in the horizontal and vertical directions can be prevented from being directly transmitted to the sliding plate or the backpack frame.

Furthermore, in the embodiments shown in FIGS. 1 to 9, only the lower part of the engine 3 was supported by the backpack frame 2, but as shown in FIG. Both of them may be supported by the backpack frame 2.

Further, in all of the illustrated examples, the engine is first attached to the elastic body so as to be rotatable about a vertical axis, but this need not be the case, and the elastic body and the engine may be fixed to each other.

Further, in all the illustrated examples, the elastic body is plate-shaped, but the elastic body is not limited to this.
For example, the legs and the like may be plate-shaped.

Furthermore, although FIG. 3 shows an elastic body with four legs extending, this number is not limited.
There may be three or five or more.

Furthermore, in the embodiments shown in FIGS. 1 to 5, long holes are provided in the legs of the elastic body, but the invention is not limited to this. It may be a hole or any other shape.

As described above, the backpack-type working machine of the present invention has the unique effect of effectively preventing engine vibrations from being transmitted to the backpack frame due to its extremely simple structure.

[Brief explanation of drawings]

1 to 5 show one embodiment of the present invention, FIG. 1 is a side view showing the entire backpack-type brush cutter, FIG. 2 is an enlarged sectional view of the main parts, and FIG. FIG. 4 and FIG. 5 are action explanatory diagrams, FIG. 6 is a perspective view of essential parts showing another embodiment of the present invention, and FIG. 7 shows still another embodiment of the present invention. 8 is a sectional view taken along the - line in FIG. 7; FIG. 9 is a schematic diagram showing still another embodiment of the present invention;
FIG. 10 is a schematic side view showing still another embodiment of the present invention. 2...Back frame, 2a...Horizontal part, 2b...Back rest part, 3...Engine, 10...Elastic body, 10a
...Central horizontal part of elastic body (engine mounting part), 1
0b...Legs of elastic body.

Claims (1)

[Scope of Claims] 1. A backpack-type working machine in which an engine for driving the working machine is mounted on a backpack frame having a horizontal part and a back support part extending upward from the front end of the horizontal part, above the horizontal part, , an elastic body having a central horizontal portion and at least three legs extending radially from the central horizontal portion is interposed between the engine and the horizontal portion; At the same time as attaching the lower part of the engine, each leg is moved upwardly with respect to the horizontal part while allowing a predetermined amount of play in the direction perpendicular to the direction in which each leg extends and in the direction in which each leg extends. A backpack-type work machine, characterized in that the engine is supported on the horizontal part by being restrained and supported so that it cannot be separated from the engine.