JPH0455480Y2 - - Google Patents

Description

[Detailed explanation of the invention] (a) Industrial application field This invention is designed to solve the problem of overload caused by a chain saw spiraling upwards during pruning work by lifting the machine up and down against the trunk of a tree. This invention relates to an engine stall prevention device for a pruning machine that can prevent the engine from stalling by switching the transmission mechanism to a neutral position.

(b) Conventional technology As a conventional pruning machine, the power of the engine
At the same time, the chain saw installed in an upright position is driven, and at the same time, a suitable number of drive wheels arranged on the machine frame are driven in forward and reverse directions via a transmission mechanism, causing the machine to spiral up and down the tree trunk, and also to move the machine up and down the tree trunk. Some are cut with a chainsaw.

By the way, this type of branch cutting machine is particularly prone to branch jamming at the tip of the chain saw, where the cutting ability is reduced, so branch jamming prevention means (for example, Jitsukō 1978−
41824) etc. are installed at the tip of the chain saw to prevent branch jamming and, in turn, to prevent engine stalling.

(c) Problems to be solved by the invention However, since this type of branch jamming prevention means functions as a countermeasure against the tip of the chain saw where branch jamming is likely to occur, it prevents engine stalling caused by other parts, such as branch jamming. No measures have been taken to prevent the engine stalling that occurs when cutting large-diameter items in the middle of the chain saw, where the cutting capacity is high, or the engine stalling that occurs when the drive wheel cannot overcome the bulge that bulges out from the trunk surface. It was true.

(d) Means for solving the problem Therefore, this invention uses the engine 1 to drive the chain saw 2, and provides a forward rotation position U, a neutral position N, and a reverse rotation position, which are provided at the lower part of the drive path of the chain saw 2. The drive wheels 3 are driven through a transmission mechanism 6 that can be switched to D, and the overload applied to the engine 1 is detected from the rotational speed fluctuation of an appropriate detection body 7 driven by the engine 1, and the overload applied to the engine 1 is detected from the rotational speed fluctuation of an appropriate detection body 7 driven by the engine 1. When the detected rotational speed value decreases, the transmission mechanism 6 is switched to the neutral position N and maintained, thereby increasing the set rotational speed of the engine 1 and causing the aircraft to rotate downward due to its own weight. , an additional configuration is that the detection object is an alternating current generator attached to the engine.

(E) Effect With the above configuration, if the chain saw or the driving wheels are prevented from driving and a certain overload is applied to the engine, the transmission mechanism is switched to the neutral position, so that the engine load drives the driving wheels. The amount of power that was being used is reduced, the engine speed increases, and the driving force of the chain saw increases, while the drive wheels are free to rotate.

(F) Embodiments Hereinafter, preferred embodiments of this invention will be described in detail by way of example with reference to the drawings.

The engine stall prevention device for a pruning machine is constructed by attaching a transmission case 4, in which an engine 1, a chain saw 2, a driving wheel 3, etc. are arranged, to a machine frame 5, in which an idler wheel (not shown), etc. is arranged. Drive wheels 3...
It is installed in a pruning machine that drives a
The overload on the engine 1 is detected by the controller 8 as a change in the rotation speed of an appropriate detection body 7 driven by the engine 1, and when the detected rotation value falls below the set rotation value, the transmission mechanism 6 is activated by the controller 8. It is configured such that the output is switched to the neutral position N via a variable speed drive section 9 (hereinafter referred to as servo motor 9) such as a servo motor.

That is, first, the detection body 7 may be something that rotates in proportion to the rotational speed of the engine 1, such as the drive wheel 3 or an appropriate gear in the transmission path 26 (to be described later), but in the embodiment, the detection body 7 may be one that rotates in proportion to the rotation speed of the engine 1. In this example, an alternating current generator 10 attached to the engine 1 is used as the detection object 7 because it has advantages such as easy and accurate detection.

Next, the controller 8 inputs the detection signal from the detection unit 11 that detects the rotational speed fluctuation of the detection body 7 and compares it with a set rotational value at which the engine does not stall. A comparator circuit 12 that outputs an output when the rotation value is below a set rotation value, an arithmetic circuit 13 that inputs this output as a priority output, performs arithmetic adjustment, and selects neutral from among forward rotation, neutral rotation, and reverse rotation rotation, and this neutral rotation output. The servo motor driver 14 receives the output of the servo motor 9 and drives the servo motor 9 in the return direction. Then, the speed change arm 17 of the speed change mechanism 6 is switched to the neutral position N. In the embodiment, this controller 8 is shown as one in which a detection section 11 and a comparison circuit 12 are integrated into a controller of an electric shift operation device 18 that electrically shifts the shift mechanism 6. . The electric speed change operation device 18 is rotatably supported by a support plate 19, and a return spring 20 is interposed between the support plate 19 and the electric speed change operation device 18, so that the electric speed change operation device 18 is always moved up and down to a horizontal elastic holding position. A shift switch actuation lever 21 configured to automatically return after operation and a cam section 21a are disposed opposite to each other in front and rear of the shift switch actuation lever 21, and the cam is activated by selectively operating the shift switch actuation lever 21 in direction A or B. Speed change switches 22, 23 for forward rotation side feed and reverse rotation side feed, in which the portion 21a is activated (ON) by pushing the corresponding side.
Then, the operating signals of the speed change switches 22 and 23 are input, the waveform is shaped, the arithmetic circuit 13 performs calculation adjustment, and one of those for forward rotation, neutral rotation, and reverse rotation is selected and output to the servo motor driver 14. a controller 8, and a servo motor 9, which drives a motor shaft 9a by a predetermined amount in the forward and reverse directions by the servo motor driver 14. It is possible to switch between the normal rotation position U, the neutral position N, and the reverse rotation position D. according to this,
To switch the shift arm 17 from the reverse position D to the neutral position N, move the shift switch operating lever 21 to A.
When the gear shift switch 22 for forward rotation is operated by the first operation in the direction, switching is possible via the controller 8 and the servo motor 9.Furthermore, in order to switch from the neutral position N to the forward rotation position U, the shift switch 22 for forward rotation is activated. It is best to perform the operation a second time. Also, to switch from the forward rotation position U to the neutral position N, it is best to operate the shift switch operating lever 21 in the direction B and then operate the shift switch 23 for reverse rotation. ,moreover,
In order to switch from the neutral position N to the reverse position D, the operation is performed in the B direction again.
The controller 8 is configured to receive a timer signal from a timer 25 having a desired pruning height setting dial 25a, and when the dial 25a reaches the setting position, a signal is sent from the timer 25 to the arithmetic circuit 13. sent and calculated and adjusted,
The motor shaft 9a of the servo motor 9 is driven and controlled by the servo motor driver 14 so that the speed change arm 17 can be switched from the forward rotation position U to the reverse rotation position D at once. The driving wheels 3, which are in position, are automatically switched to reverse drive, and the ascending aircraft can be lowered relative to the trunk.

Next, the transmission mechanism 6 is built into a transmission path 26 that transmits the power of the engine 1 to an appropriate number of drive wheels 3, and has a transmission shaft 27 with a large gear 28 for forward rotation and a sprocket 29 for reverse rotation. The forward/reverse clutch body 30 is loosely fitted onto the speed change shaft 27 and spline-fitted to the speed change shaft 27 so that it can only slide. It is configured to be slidably moved to a reverse position D and a neutral position N, and to be selectively engaged with and disengaged from both 28 and 29. Therefore, when the transmission arm 17 is in the forward rotation position U, the forward/reverse clutch body 30 is engaged with the large gear 28 for forward rotation (solid line in FIG. 2), and when it is in the reverse rotation position D, it is engaged with the sprocket 29 for reverse rotation. When it is in the neutral position N, which is between the two positions UD, it is not engaged with either position. Further, the transmission path 26 is built in the transmission case 4, and the output shaft 1a of the engine 1 is bored in the transmission case 4, and the transmission path 26 is connected to the reduction gear group 31,
In addition to being transmitted to the drive wheels 3 through the transmission mechanism 6, each pair of reduction bevel gears 18, etc., the chain saw 2 mounted in an upright manner on the transmission case 4 also has
Power is transmitted from the output shaft 1a through a group of same-speed bevel gears 33.

According to the above, normally, the chain saw 2 is driven by the power of the engine 1, and the drive wheels 3 are driven in forward and reverse directions to spiral the machine body up and down the tree trunk, and the chain saw 2 cuts the branches on the way up. The pruning work is then carried out.

However, when the chain saw 2 bites into the branch it is cutting, it becomes overloaded and the rotational speed of the engine 1 decreases, causing the detected rotational speed of the detection unit 11 that detects the rotational speed fluctuation of the detection body 7 to decrease. will also decrease. When this detected rotational value falls below the set rotational value, an output is sent to the arithmetic circuit 13 from the comparator circuit 12, which constantly compares both rotational values. The arithmetic circuit 13 calculates and adjusts this output as a priority output, and sends the neutral output to the servo motor driver 14, which drives the gear shift arm 1 via the servo motor 9.
7 from normal rotation position U to neutral position N, drive wheel 3
Power is no longer transmitted to... This results in
The overload of the engine 1 is reduced by the power that was driving the drive wheels 3..., and the rotation speed of the engine 1 increases,
Engine stall is avoided. In addition, at the same time as avoiding this engine stall, the chain saw 2 rotates faster than the normal rotation while the machine is ascending, and the cutting capacity becomes higher than normal.In addition, the chain saw 2 has a spiral descending force due to the machine's own weight, so The aircraft descends without any interference. Then, by operating the speed change switch operating lever 23 in the direction A, the operator switches the speed change arm 17 from the neutral position N to the normal rotation position U, raises the machine again, and removes the branch that was being cut previously. Cutting can be done with constant rotation.
At this time, if the chain saw 2 bites into this branch again, the machine body will descend in the same way, so the operator can repeat the above procedure. However, without having to lower the aircraft to the ground each time, it is possible to improve work performance by configuring the gear shift arm 17 to be automatically switched from the neutral position N to the forward rotation position U after a certain period of time and raised again. Become. The above will allow the aircraft to descend without stalling even in the event of a problem due to the drive wheels 3 not being able to get over the bulge on the trunk surface while the aircraft is ascending. If the aircraft is raised so that the drive wheels 3 are displaced from the bulge, it will be able to pass through the bulge.

(g) Effects of the invention As described above, this invention prevents the engine 1 from being overloaded due to the chain saw 2 biting into a branch with a large diameter, the drive wheel 3 hitting a bulge on the trunk surface, etc.
When the detected rotational speed value obtained by appropriately detecting the rotational speed fluctuation of the detection body 7 falls below the set rotational speed value, the transmission mechanism 6 is switched to the neutral position N, so that the amount of power that was driving the drive wheels 3 is applied to the engine 1. The load can be reduced, the number of revolutions of the engine 1 will be higher than the set number of revolutions, and stalling of the engine can be prevented. Also, since the transmission mechanism 6 is switched to the neutral position N, the driving wheels 3...
The load on the engine 1 can be reduced by the amount of power that was driving the engine 1, and the engine 1 rotates above the set rotation speed, and the chain saw 2, which had been biting into the branch, now rotates faster than its normal rotation, and the engine 1 rotates faster than the normal rotation, and the chain saw 2, which had been biting into the branch, is now rotating faster than the normal rotation. The biting part of the branch is cut by the chain saw 2, and since the transmission mechanism 6 is switched to the neutral position N, the drive wheels 3 are free to rotate, so the weight of the machine causes the machine to descend.

When the drive wheels 3 of the descended machine are driven in normal rotation again to raise the machine, the diameter of the branch being cut has become smaller, so the constantly rotating chain saw 2 cuts the branch into a clean cut. disconnected. On the other hand, if the descended aircraft is shifted and raised, the drive wheels 3 can pass by avoiding the bulging position.

Incidentally, when the detecting body 7 is appropriately used as an alternating current generator 10 attached to the engine 1, the frequency can be used, so detection becomes easy and accurate, and the reliability of this engine stall prevention device can be improved.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the engine stall prevention device for a pruning machine according to this invention, and FIG. 2 is a schematic diagram showing a transmission path incorporating the engine stall prevention device. Code, 1...Engine, 2...Chain saw, 3
...Drive wheel, 6...Transmission mechanism, 7...Appropriate detection body, 10...Alternator, U...Normal rotation position, N...
...Neutral position, D...Reverse position.

Claims (1)

[Scope of utility model registration request] The engine 1 drives the chain saw 2, and the engine 1 is provided below the drive path of the chain saw 2.
Drive wheels 3 are driven via a transmission mechanism 6 that can be switched between a normal rotation position U, a neutral position N, and a reverse rotation position D, and the overload applied to the engine 1 is detected by an appropriate detection body 7 driven by the engine 1. Detected from rotational speed fluctuations,
When the detected rotational speed falls below the set rotational speed, the transmission mechanism 6 is switched to and maintained at the neutral position N, thereby increasing the set rotational speed of the engine 1 and causing the aircraft to rotate downward due to its own weight. A stall prevention device for pruning machines.