JP2790254B2 - Portable work machine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a portable working machine using an internal combustion engine such as a brush cutter, a hedge trimmer, a chain saw or the like as a prime mover.

[Prior Art] Conventionally, this type of portable working machine has been provided with a throttle operating means for fully opening a throttle valve of an internal combustion engine by a user's operation.

[Problems to be Solved by the Invention] In such a conventional portable work machine, the throttle valve can be fully opened by the user operating the throttle operating means by gripping or the like, so that the load can be compared. In many cases, the throttle valve is fully opened even during light work, and the rotation speed of the internal combustion engine becomes unnecessarily high, resulting in an increase in noise and a decrease in fuel consumption. On the other hand, in order to avoid this, if the throttle valve is not fully opened but is opened to the middle during normal work with a relatively light load, the rotation speed of the internal combustion engine will drop when the load suddenly increases. Could not do the proper work. Therefore, in this case, each time the load changes, the operator must operate the throttle operating means to open and close the throttle valve, which is troublesome.

The present invention solves such disadvantages of the prior art, and in ordinary work where the load is relatively light, the number of revolutions of the internal combustion engine does not become unnecessarily high, and noise and fuel consumption can be reduced. It is another object of the present invention to provide a portable working machine capable of automatically opening a throttle valve when a heavy load is applied, performing appropriate work, and improving operability.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a portable working machine in which an internal combustion engine is used as a prime mover and a handle side is relatively displaced with respect to a main body side including a working member under heavy load. Throttle operation means for opening a throttle valve of the internal combustion engine to a predetermined intermediate opening degree by a user's operation; detection means for detecting the presence or absence of a relative displacement of the handle side with respect to the main body side exceeding a predetermined value; When the relative displacement occurs in response to the detection signal, an actuator that opens the throttle valve to an opening that is more open than the intermediate opening regardless of the operation state of the throttle operating means is provided. is there.

[Operation] In the present invention, unlike the above-mentioned conventional portable working machine,
Since the throttle operating means for opening the throttle valve of the internal combustion engine to a predetermined intermediate opening by the user's operation is provided, even if the user operates the throttle operating means, the throttle valve is only moved to the predetermined intermediate opening. It can not be opened, it can not be wide open like full open. Therefore,
The speed of the internal combustion engine does not increase unnecessarily during normal operation with a relatively light load. Further, according to the present invention, at the time of heavy load, the handle side is relatively displaced with respect to the main body side including the working member, and the relative displacement is detected by the detecting means,
An actuator is actuated based on a detection signal of the detection means, and the throttle valve is opened by the actuator to an opening which is further open than the intermediate opening regardless of an operation state of the throttle operation means. That is, at the time of heavy load, the throttle valve automatically opens greatly beyond the intermediate opening.

Hereinafter, an embodiment in which the present invention is applied to a brush cutter A will be described with reference to the drawings.

FIG. 1 is a perspective overall view of the mower A, FIG. 2 is a partially cut-away longitudinal sectional view showing a main part thereof, and FIG. 3 is an explanatory view of a throttle valve operation.

As shown in FIG. 1, the mower A has an internal combustion period 1 such as a small air-cooled two-stroke engine provided with a recoil star 2 and a fuel tank 3 serving as a prime mover.
A working shaft 6 extending from the shaft, an operating rod 6 having the built-in conductive shaft 5 and fixed to the internal combustion period 1 side, and a cutting blade 7 serving as a working member rotatably provided at the tip of the operating rod 6. It comprises a main body 4 and a handle 8 in a U-shape provided at an appropriate position of the operation rod 6.

The handle 8 is configured to be relatively displaced with respect to the main body 4 under heavy load.

That is, in the case of the drawing embodiment, as shown in FIG.
A U-shaped mounting bracket 9 is fixed to the center of the handle 8, an annular mounting bracket 10 is fixed to the operation rod 6, and a rubber vibration-proof material 11 is provided between the mounting brackets 9 and 10. Attached through. Therefore, when the user sets the handle 8
When a heavy load is applied to the cutting blade 7 while working while holding the handle, the user applies a large force to the handle 8, and as a result, the vibration isolator 11 is deformed, and the handle 8 and the mounting The metal fitting 9 is relatively displaced with respect to the operating rod 6 and the mounting metal 10 on the main body 4 side. In addition, the vibration isolator 11
It also has a function of absorbing vibration generated from the internal combustion engine 1 and the cutting blade 7 and preventing the vibration from being transmitted to the handle 8.

Further, a throttle operating means 12 for opening the throttle valve 15 of the internal combustion engine 1 to a predetermined intermediate opening degree by a user's operation is provided. In the embodiment shown in the drawings, the throttle operating means 12 includes a throttle operating lever 13 attached to the handle 8 as shown in FIGS. 1 and 3, and a throttle wire one end of which is locked to the throttle operating lever. And an interlocking mechanism (not shown) including a throttle lever 16 fixed to the throttle valve 15 and the other end of the throttle wire 14 locked. The throttle wire 14 is covered with an outer tube 17 except for both ends.
As shown in FIG. 3, when the throttle lever 16 is at the fully closed position, the intermediate opening position or the fully open position, the throttle valve 15 is fully opened and the predetermined intermediate opening Or, it is designed to be fully opened. The throttle lever 16 is urged counterclockwise by a spring (not shown) toward the fully open position corresponding to the idling rotation of the internal combustion engine 1. Further, the throttle operation lever 13
The operation range is limited by a stopper or the like (not shown), and the interlocking range of the throttle lever 16 by operating the throttle operation lever 13 is set from the fully closed position to the intermediate opening position. The intermediate opening position is determined according to the number of rotations of the internal combustion engine required for normal work with a relatively light load.

Further, detecting means 18 for detecting a relative displacement of the handle 8 side relative to the main body 4 side exceeding a predetermined value is provided. In the case of the illustrated embodiment, a so-called tentacle-type lever switch is used as the detecting means 18, and as shown in FIG.
And the tip of the flexible tentacle 20 is inserted into a hole 21 having a diameter larger than that of the tentacle 20 in accordance with a change position to be detected by the mounting bracket 9 on the handle 8 side.
The lever switch has a tentacle 20 with respect to the switch body 19.
When the switch is inclined, the conduction / non-conduction state of an electric contact (not shown) built in the switch main body 19 is switched. Therefore, in the case of the embodiment shown in the drawings, the handle 8 and the mounting bracket 9 are
Is relatively displaced, the tip of the tentacle 20 is attached to the mounting bracket 9.
Is pressed by the periphery of the hole 21, and the tentacle 20 is tilted, and the contact in the switch body 19 is switched to detect the presence or absence of the relative displacement.

However, the detecting means 18 is not limited to the lever switch.

Further, when the relative displacement occurs, the throttle valve 15 is set to a further opening than the intermediate opening regardless of the operation state of the throttle operating means 12 in response to the detection signal of the detecting means 18. Open actuator 22
Is provided. In the case of the illustrated embodiment, the actuator
An electromagnetic solenoid is used as 22. As shown in FIG. 3, the solenoid is fixed near the throttle lever 16, and its operating rod 23 is connected to the throttle lever 16 via a wire 24. When the operating rod 23 is pulled to rotate the throttle lever 16 to the fully open position and the power is cut off, the operating rod 23 can be freely protruded and the throttle valve 15 is rotated by the spring biasing force to the fully closed position. It has been made possible. It should be noted that when the operating rod 23 is pulled, the throttle valve 15 does not necessarily need to be turned to the fully open position, but may be turned before the throttle valve 15. The electromagnetic solenoid, which is the actuator 22, is connected to an electric control circuit (not shown), and energization is maintained when the conduction / non-conduction state of the electric contact of the lever switch, which is the detection means 18, is continuously switched in a short time. In addition, when the electric contact of the lever switch returns to the original state for a certain period of time, the power supply is cut off. Since the electric control circuit itself is well known, a detailed description thereof will be omitted.

The actuator 22 is not limited to the electromagnetic solenoid.

According to the bush cutter A according to the present invention having the above-described configuration, the user holds the handle 8 and operates the throttle operating lever 13 to perform work such as mowing. At this time, even if the throttle operation lever 13 is operated, the throttle lever 16 rotates only from the fully-closed position to the intermediate opening, so that the throttle valve 15 cannot be opened as widely as fully opened, and the load is relatively small. During a light normal operation, the rotation speed of the internal combustion engine 1 does not become higher than necessary. Therefore, noise and fuel consumption are reduced. During this normal operation, the handle 8
Side is not displaced relative to the main body 4 by a predetermined value at which the detecting means 18 operates, so that the electric contact of the lever switch as the detecting means 18 does not switch, and the electromagnetic solenoid as the actuator 22 is not energized. 22 does not affect the operation of the throttle lever 16 at all.

Next, when a heavy load is applied during the work, the handle 8 side is relatively displaced with respect to the main body 4 side, so that the tentacle 20 of the lever switch serving as the detecting means hits the inner surface of the hole 21 of the handle mounting bracket 9 and the electrical contact is made. Then, the electromagnetic solenoid as the actuator 22 is energized, the throttle lever 16 is rotated to the fully open position regardless of the operation state of the throttle operation lever 13, and the throttle valve is fully opened. As described above, when a heavy load is applied to the heel, the throttle valve is automatically opened widely, so that proper operation can be performed without lowering the rotation speed of the internal combustion engine 1 and operability is improved.

In the above description, an example in which the present invention is applied to a mower is described, but the present invention can be applied to various other portable working machines such as a hedge trimmer and a chain saw.

[Effects of the Invention] According to the present invention, the number of revolutions of the internal combustion engine does not become unnecessarily high during normal work with a relatively light load, so that an effect of reducing noise and fuel consumption can be obtained. . In addition, when a heavy load is applied, the throttle valve opens automatically and the internal combustion engine does not lose its load and does not drop, so that appropriate work can be performed and operability is improved. And the like.

[Brief description of the drawings]

1 shows an embodiment of the present invention. FIG. 1 is an overall perspective view of a mower, FIG. 2 is a partially cutaway vertical sectional view showing a main part thereof, and FIG. is there. 1 ... internal combustion engine, 4 ... body, 7 ... working member, 8 ...
Handle, 12 ... Throttle operation means, 18 ... Detection means, 22 ... Actuator.

Claims (1)

(57) [Claims] 1. A portable working machine in which an internal combustion engine 1 is used as a prime mover and a handle 8 is relatively displaced with respect to a main body 4 including a working member 7 under heavy load, and a slot valve of the internal combustion engine 1 is operated by a user. Throttle operating means 12 for opening the throttle valve to a predetermined intermediate opening degree, detecting means 18 for detecting the presence or absence of a relative displacement of the handle 8 side relative to the main body 4 side exceeding a predetermined value, and receiving a detection signal of the detecting means 18 A portable work machine provided with an actuator 22 that opens the throttle valve to an opening that is further open than the intermediate opening regardless of the operation state of the throttle operating means 12 when the relative displacement occurs. .