JP2007051621A - Engine-driven working machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine-driven working machine provided with an automatic control means for engine revolution which enables reduction of worker's load, improvement of working efficiency, fuel economy and safety by automatically controlling the throttle opening to enhance efficiency in response to load fluctuation. <P>SOLUTION: The engine-driven working machine has an engine revolution-control means 100 which is provided with a throttle control motor 8, and a controller 1 for outputting to the motor 8, a control signal for automatically shifting the engine revolution into the range of working threshold when the engine revolution reaching the working revolution fluctuates out of the range of working threshold corresponding to the working revolution. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an engine-driven work device having an engine speed automatic control means, and more specifically, an engine speed capable of automatically adjusting a throttle opening in accordance with a load fluctuation with respect to a rotary blade. The present invention relates to an engine-driven work tool having automatic control means.

  A configuration of a conventional brush cutter 300 is shown in FIG.

  The brush cutter 300 has a configuration in which the rotary blade 22 and the engine (prime mover) 3 are connected to the cover tube 21. The cover tube 21 includes a handle 24 and a grip 25, and the handle 24 includes a rotatable throttle operation lever 26. A drive shaft (not shown in the drawing) is rotatably inserted into the cover tube 21, and a rotary blade 22 is connected to the tip of the drive shaft via an interlocking mechanism (not shown in the drawing). Has been. The other end of the drive shaft is connected to the engine 23 together with a centrifugal clutch housed in a clutch housing (not shown in the drawing).

  Although not shown in the figure, the brush cutter 300 includes a starter for starting the engine 23 and a stop switch for safely stopping the brush cutter 300.

  The brush cutter 300 having such a configuration transmits the output of the engine 23 to the rotary blade 22 via the drive shaft in order to mow the grass, and rotates the rotary blade 22. The operator can perform the work by holding the handle 24 and / or the grip 25 with both hands and swinging the cover tube 21, and operating the throttle operation lever 26, whereby the carburetor inside the engine 23 is connected via the wire 27. The opening of the throttle valve (not shown in the figure) can be adjusted to adjust the output of the engine 23.

  The engine 23 started by the starter normally maintains idling rotation and becomes high rotation as necessary. In order to perform such an engine function, a tension that normally maintains the throttle opening is applied to the throttle valve of the carburetor, and is connected to the throttle valve via a wire 27 in order to increase the rotation of the engine 23. It is necessary for the operator to turn the throttle operating lever 26 against the tension.

  In general, the rotation of the engine is maintained by a resistance provided inside the fixed throttle operation lever 26 and by the grip of the operator's hand by a repulsive throttle operation lever (not shown in the drawing). .

  In the brush cutter 300 provided with the fixed throttle operation lever 26, since the rotation of the engine 23 is held, the rotation of the rotary blade 22 is also held. Therefore, when the grass cutter 300 is operated to mow the grass, the grass becomes a load and the rotation of the rotary blade 22 is reduced, and the load is transmitted to the engine 23 via the drive shaft. As a result, the engine The rotational speed and output of the power supply are reduced, and the efficiency of the brushing work is reduced. In this case, the worker adjusts the throttle operation lever 26 to the high rotation position again to increase the rotation of the engine 23 in order to improve work efficiency. However, when the engine 23 is used at a high speed, the fuel consumption is extremely deteriorated. Further, the rotating blade 22 after being released from the load is suddenly increased in rotational speed and is in an idling state, which gives fear to the worker.

  In order to proceed with the work while achieving both work efficiency and fuel efficiency, the worker must adjust the position of the throttle operation lever 26 according to the engine rotation. Force the burden. Since the mowing operation is dangerous, complicated operations should be avoided.

  With a brush cutter equipped with a repulsive throttle control lever, the throttle control lever can be adjusted according to how the operator's hand is gripped. It becomes difficult to keep the position of the lever constant.

  Japanese Patent Application Laid-Open No. 2004-133867 discloses a technique for performing a throttle operation without frequently adjusting the throttle operation lever position by the operator and without placing a burden on the operator's fingers.

The technique described in Patent Document 1 adjusts the engine speed based on an electrical signal generated when an operator operates an operation switch provided on a handle portion. Since the operation of the operator in this technique is less than that of the fixed or repulsive throttle operating lever described above, the engine speed can be adjusted with a small operating force.
JP 2003-301729 A (published on October 24, 2003)

  However, in the technique of Patent Document 1, it is left to the operator to determine the high rotation (high output) of the engine, and the operator must frequently operate the switch according to the load fluctuation applied to the rotary blade. This is the same as conventional technology.

  The present invention has been made in view of the above-described problems, and an object thereof is frequently used by an operator in an engine-driven work device in which work efficiency is reduced due to a load generated in a work site during work. An object of the present invention is to provide an engine-driven work tool capable of automatically maintaining work efficiency without requiring complicated operations.

In order to solve the above problems, an engine-driven work device according to the present invention controls a throttle switch opening and a work switch for switching between an engine speed during work and an engine speed during non-work. An engine speed control means including a throttle control motor and a controller that outputs a control signal for controlling the drive of the throttle control motor,
The controller
The operator outputs a control signal to the throttle control motor to increase the engine speed from the idling speed to the working speed by switching the work switch,
A control signal for automatically shifting the engine speed within the working threshold range when the engine speed that has reached the working speed fluctuates outside the working threshold range corresponding to the working speed. It outputs to the throttle control motor.

  Since the engine-driven work machine according to the present invention adopts the above-described configuration, the engine speed can be automatically increased or decreased to a set speed simply by operating the work switch. The complexity of operation switch operation can be eliminated. Further, according to the present invention, the throttle opening is automatically adjusted according to the load fluctuation during the operation, so that the operation can be performed while the engine speed is kept constant.

  In the engine-driven work device according to the present invention, it is preferable that the controller outputs a control signal for maintaining the engine speed at the idling speed to the throttle control motor when not working.

  By adopting the above-described configuration, the engine-driven work machine according to the present invention can normally maintain the rotational speed at the idling rotational speed even in an engine that does not include an idle screw.

In the engine-driven work implement according to the present invention, the controller is
During the period in which the control is performed in the engine speed control means, the engine speed is always calculated based on the engine pulse input via the ignition coil lead wire,
If the calculated engine speed is outside the working threshold range corresponding to the working rotational speed, calculate the motor operation amount necessary to shift the engine rotational speed within the working threshold range;
It is preferable to output a signal representing the motor operation amount to the throttle control motor.

  Since the engine-driven work equipment according to the present invention adopts the above-described configuration, the throttle opening is automatically adjusted as necessary according to the fluctuation of the engine speed without the operator being conscious, Work efficiency and fuel consumption can be improved. Further, the operator can concentrate on the work without worrying about the engine speed due to the load fluctuation, and thus the safety can be improved.

  The engine-driven work machine according to the present invention preferably further includes a multistage switch for switching a plurality of work rotation speeds.

  As described above, the engine-driven work device according to the present invention further includes a multi-stage switch for switching a plurality of work rotation speeds, so that the operator can arbitrarily set the work rotation speed during the work. There is an effect that it can be easily changed.

  In the engine-driven work device according to the present invention, the controller controls the throttle control motor so as to reduce the engine speed to less than a drive threshold based on an input signal indicating that the work switch or the main switch is off. Is preferred.

  As described above, the engine-driven work device according to the present invention rapidly reduces the engine speed to less than the drive threshold when the work switch or the main switch is off. Therefore, when the work is not desired, the engine no-load state can be quickly provided to ensure the safety of the worker.

  In the engine-driven work implement according to the present invention, the controller includes a stop switch relay that stops the engine when the engine speed is less than the drive threshold and the main switch of the engine-driven work implement is off. It is preferable to operate.

  As described above, in the engine-driven work device according to the present invention, the controller operates the stop switch relay only when the engine speed is less than the drive threshold and the main switch is off. It is effective in not damaging each component which comprises a working tool with the sudden engine stop. In addition, as described above, when the main switch is off, the engine speed is quickly reduced below the driving threshold value. Therefore, even if the operator suddenly turns off the main switch for some reason during work, the engine Can be stopped quickly, and the safety of workers can be ensured.

  In the engine-driven work device according to the present invention, the engine speed control means may include an idling position detection sensor that detects whether or not the throttle opening is an idling position and outputs a detection signal to the controller. preferable.

  Usually, even if the throttle opening is at the idling position, there is a slight time difference until the actual engine speed decreases to the idling speed. Therefore, if the throttle opening is determined depending on the engine speed, the throttle opening may be smaller than the idling position. However, the engine-driven work device according to the present invention further includes an idling position detection sensor for detecting whether or not the throttle opening number is the idling position, as described above, and therefore includes an idle screw. Even if there is no engine, the idling position can be strictly controlled, and an undesirable engine stop can be avoided.

  In the engine-driven work device according to the present invention, it is preferable that the ignition coil lead wire is connected to a capacitor, and the capacitor is used as a power source for the engine speed control means.

  According to the present invention, since it is used as a power source by adding only a capacitor to the ignition coil already mounted on the engine in a commercially available engine-driven work equipment, there is no need to install a power source such as a battery, The operator does not need to perform troublesome charging or battery replacement, and can solve the malfunction due to the battery running out. Furthermore, since the additional component is only a capacitor, the apparatus can be reduced in size and weight, and the manufacturing cost can be reduced.

  The engine-driven work device according to the present invention is preferably a brush cutter, a lawn mower, or a pulverizer.

  The engine-driven work device according to the present invention is preferably a portable brush cutter.

  As described above, the engine-driven work device according to the present invention keeps the engine speed within the work threshold when the engine speed fluctuates outside the work threshold corresponding to the work speed. Since the controller for outputting the control signal for automatically shifting to the throttle control motor is provided, the throttle opening is automatically adjusted according to the load fluctuation during the work. Therefore, there is an effect that the operation can be performed while the engine speed is kept constant.

  An example in which the engine-driven work tool according to an embodiment of the present invention is a portable brush cutter will be described below. As used herein, the “engine-driven work tool” is intended to be a tool for performing work using the engine source directly or indirectly, with the drive source as the engine. A device that performs a work by generating a turning motion based on the engine rotation is intended. In the engine-driven work device according to the present invention, the engine speed during work is “working speed”, and the engine speed during non-working is “idling speed”. As used herein, an engine speed “less than the driving threshold” is intended to be a state in which the engine is idling naturally with no load, and “idling speed” is the engine after starting. A minimum speed is intended.

  Further, as used herein, the “working threshold value” is intended to be a predetermined value of the engine rotational speed provided to maintain the engine rotational speed at the working rotational speed. It consists of a “lower limit threshold value” that is a lower limit value that can be accepted as a number, and an “upper limit threshold value” that is an upper limit value that can be accepted as a desired working rotational speed. The “driving threshold value” is intended to be the engine speed when the engine is switched from the no-load state to the loaded state. In other words, when the engine speed decreases below the threshold during work, the centrifugal clutch is disengaged and the engine is not loaded.

  First, the configuration and operation of the brush cutter 200 according to the present embodiment will be described with reference to FIGS.

  FIG. 3 is a perspective view showing the configuration of the brush cutter 200 according to the present embodiment. As shown in FIG. 3, the brush cutter 200 according to the present embodiment has a configuration in which a rotary blade 22 and an engine 23 are connected to a cover tube 21 having a handle 24 (24a / 24b) and a grip 25. One handle 24a has a main switch 2 for maintaining the engine speed in an operating state (on) or a stopped state (off), and the engine speed in the operating state is an idling speed (engine speed when not working). A work switch 3 is provided for switching between the working speed (engine speed during work). Further, the cover tube 21 is provided with a box 10 provided with a multistage switch 4 for setting a working rotational speed suitable for work.

  The configuration of the box 10 provided with the multistage switch 4 is shown in FIG. 4, and the configuration of the handle 24a provided with the main switch 2 and the work switch 3 is shown in FIG. The box 10 is attached to the cover tube 21 and has an operation amount correction setting switch 7 together. In FIG. 4, the box 10 including the multistage switch 4 and the operation amount correction switch 7 is shown. However, these do not necessarily have to exist on the same member, and may be provided separately as necessary. Good. Moreover, since the multistage switch 4 attached to the cover tube 21 is not frequently operated during work, it can be installed at any part of the brush cutter 200 as long as the work is not hindered. However, considering that the operator can change the setting during the mowing work, the multistage switch 4 is preferably in the vicinity of the grip 25 as shown in FIG. The shapes of the main switch 2 and the work switch 3 are not limited to those shown in FIG.

  The work switch 3 itself may be a multistage switch.

  When the brush cutter 200 according to the present embodiment has a power source, the operator turns on the main switch 2 and the engine 23 is started by a cell or a starter (not shown). The speed of the engine 23 that has been started is maintained at the idling speed. Further, when the operator turns on the work switch 3, the engine speed is increased to the set working speed. As a result, the operator can perform a brush cutting operation using the brush cutter 200. After the work, when the worker turns off the work switch 3, the engine speed decreases to the idling speed. Next, when the operator turns off the main switch 2, the engine 23 is stopped. The setting of the working rotational speed by the multistage switch 4 may be performed before or after the engine is started, or may be during the work.

  When the brush cutter 200 according to the present embodiment does not have a power source, an operator starts the engine 23 with a starter (not shown), so that the started rotational speed of the engine 23 is maintained at an idling rotational speed. The Therefore, the main switch 2 need only have an off function without an on function.

  The conventional brush cutter 300 as shown in FIG. 4 requires complicated operations such as operating the throttle operating lever 26 in order to increase the engine speed when the engine speed decreases due to the load on the rotary blade 22 during operation. And However, in the brush cutter 200 according to the present embodiment, the engine speed is controlled by the engine speed automatic control unit 100 so as to keep the engine speed constant according to the load variation on the rotary blade 22.

  Further, in the conventional brush cutter 300, if an operator turns off the main switch (not shown) in a state where the engine speed is not sufficiently lowered, the parts constituting the brush cutter are damaged due to a sudden engine stop. Will be given. However, in the brush cutter 200 according to the present embodiment, when the operator turns off the main switch 2 or the work switch 3 during work, the engine speed is reduced so that the engine speed immediately decreases to a no-load state (less than the driving threshold). It is controlled by the automatic control means 100. Therefore, the safety of the operator is ensured, and damage to the parts of the brush cutter can be avoided.

  The first embodiment of the engine speed automatic control means 100 mounted on the brush cutter 200 according to this embodiment will be described below with reference to FIGS.

  FIG. 1 shows a functional block diagram of the engine speed automatic control means 100 according to the present embodiment. As shown in FIG. 1, the engine speed automatic control means 100 includes a main switch 2, a work switch 3 and a multistage switch 4, a controller 1, an ignition coil conductor 5, an idle position detection sensor 6, and an operation amount correction setting switch 7. And a throttle control motor 8 and a stop switch relay 9. The controller 1 is connected to the main switch 2, the work switch 3, the multi-stage switch 4, the ignition coil lead wire 5, the idle position detection sensor 6, and the operation amount correction setting switch 7 to form a circuit. The signal (input signal) is processed to generate an output signal. The controller 1 is also connected to the throttle control motor 8 and the stop switch relay 9 to form a circuit, and outputs the generated output signal to the throttle control motor 8 and the stop switch relay 9 to control them.

  In the present embodiment, the controller 1 has a configuration having a plurality of functional parts such as a calculation unit and a storage unit. In the controller 1, the arithmetic unit executes a program stored in the storage unit, and controls peripheral circuits such as an input / output circuit (not shown), thereby realizing control. As the peripheral circuit, a storage unit for storing various set values (for example, idling rotation speed, driving threshold, working threshold, etc.), an actual engine rotation value calculated by the calculation unit, and a stored value are stored. Examples include, but are not limited to, a comparison unit, a circuit formed between a control unit that controls the throttle control motor according to a value calculated by the calculation unit based on the comparison result, and the like. All of these functional blocks are controlled by the calculation unit, and the specific configuration, function, and the like of these functional blocks are not particularly limited.

  In the case where the brush cutter 200 as shown in FIG. 3 has a power source, when the main switch 2 is turned on, power is supplied from the power source to the engine speed automatic control means 100, and control by the controller 1 is started. The

  When the engine 23 is started, an engine pulse (ignition pulse) is constantly input to the controller 1 via the ignition coil conductor 5. The controller 1 always calculates the engine speed based on the input engine pulse. The line for detecting the engine pulse may be obtained by clamping the ignition coil conductor 5 or may be obtained by branching a new line from the ignition coil conductor 5. In this case, the ignition coil conductor may be the primary side or the secondary side.

  After starting the engine 23 and before work, that is, when the main switch 2 is on and the work switch 3 is off, the controller 1 calculates an operation amount for maintaining the throttle opening required for idling rotation. Then, the throttle control motor 8 is driven based on the calculated operation amount. The throttle valve is changed to the idling position and maintained by the driven throttle control motor 8. As used herein, “throttle opening” is intended to be “the angle of a throttle valve (valve)”.

  When the engine 23 is equipped with an idle screw (not shown), the throttle opening required for the idling speed of the engine can be manually set. Therefore, the throttle control motor 8 is controlled by the controller 1 in order to maintain the idling speed. There is no need to drive.

  Thus, the throttle control motor 8 controls the throttle opening of the carburetor inside the engine, and the controller 1 outputs a control signal for controlling the drive of the throttle control motor 8.

  The throttle valve is provided with an idling position detection sensor 17 for detecting an idling position. The fact that the throttle valve has reached the idling position is detected by the idling position detection sensor 17, and the detected signal is input to the controller 1. The idling position detection sensor 17 may be provided outside the throttle valve to detect the position of the throttle valve.

  The operation amount for driving the throttle control motor 8 so as to supply the necessary engine speed is calculated by the controller 1 based on the setting information input from the multistage switch 4. For example, FIG. 4 shows a multistage switch 4 in the form of 3 notches.

  In the case of a two-cycle engine having a displacement of about 20 to 25 cc used for a portable brush cutter, a preferable working rotational speed is about 6000 to 8000 rpm, and a driving threshold is about 5000 rpm. In the multistage switch 4 shown in FIG. 4, rotation speeds such as 6000 rpm, 7000 rpm, and 8000 rpm are assigned in advance, and the work rotation speed is set by switching the multistage switch 4. For example, when the work switch 3 is turned on with the multi-stage switch 4 set to 6000 rpm, the engine speed increases from the idling speed to 6000 rpm, and then when the work switch 3 is turned off, the engine speed is again idling. Decreases to rotation speed. In the case of a two-cycle engine with a displacement of about 20 to 25 cc, the preferred idling speed is about 2500 to 3000 rpm, but it can be appropriately changed depending on the use environment.

  When the work switch 3 is turned on by the operator, the controller 1 compares the working rotational speed input from the multistage switch 4 with the actual rotational speed, calculates the throttle opening manipulated variable based on the deviation, The throttle control motor 8 is driven based on the calculated operation amount. As a result, the engine speed increases from the idling speed to the working speed. An operation amount correction setting switch 7 is further provided to correct the calculated motor operation amount based on a signal from the operation amount correction setting switch 7 and drive the throttle control motor 8 by the corrected operation amount. More preferred.

  Even if the engine rotational speed reaches the working rotational speed, if the work is started, the engine rotational speed decreases due to the load caused by the mowing work. However, in the brush cutter 200 according to the present embodiment, the engine rotational speed is always maintained at the working rotational speed set through the automatic control by the controller 1.

  The controller 1 (1) always calculates the engine speed based on the engine pulse input via the ignition coil conductor 5 during the period when the control is executed by the engine speed control means 100, and (2) the calculation If the engine speed thus determined is outside the working threshold range corresponding to the working rotational speed, a motor operation amount required to shift the engine rotational speed within the working threshold range is calculated, and (3 ) A signal representing the motor operation amount is output to the throttle control motor.

  The engine speed calculated when the main switch 2 is turned on is recorded in the storage unit of the controller 1. In addition, in the storage unit of the controller 1, work threshold values (upper limit threshold value and lower limit threshold value) of the engine speed corresponding to the work speed set by the multistage switch 4 are recorded in advance. When both the main switch 2 and the work switch 3 are on, the calculation unit of the controller 1 is recorded in advance in the actual engine speed recorded in the storage unit and in the storage unit in accordance with the program stored in the storage unit. Compare the working threshold. When the actual engine speed falls below the lower threshold or exceeds the upper threshold, the calculation unit of the controller 1 compensates for the deviation between the actual engine speed and the working threshold (upper threshold or lower threshold). The amount of motor operation necessary for the calculation is calculated and a signal is output to the throttle control motor.

  That is, when the engine speed starts to decrease due to the load during the mowing operation, the controller 1 is based on the deviation from the on signal of the main switch 2, the on signal of the work switch 3, and the engine speed below the lower limit threshold. Then, a positive operation amount necessary for controlling the throttle opening to a desired angle is calculated, and the throttle control motor 8 is further driven. When the rotary blade 22 is released from the load and the engine speed increases, the controller 1 determines that the main switch 2 is turned on, the work switch 3 is turned on, and the deviation from the engine speed exceeding the upper limit threshold. Then, a negative operation amount necessary to control the throttle opening to a desired angle is calculated, and the drive of the throttle control motor 8 is reduced.

  When the work switch 3 is turned off by the worker who has finished the work, the controller 1 to which the signal is inputted simultaneously drives the throttle control motor 8 so that the engine speed immediately falls below the driving threshold. Then, the operation amount necessary for controlling the throttle control motor 8 is determined as the “idling amount”, and the throttle control motor 8 is driven so that the throttle opening becomes the idling position. As a result, the engine speed decreases from the working speed to the idling speed. Next, when the operator turns off the main switch 2, the controller 1 operates the stop switch relay 9 to stop the engine 23.

  As described above, when the controller 1 controls the throttle opening of the carburetor in the engine, (1) the operator switches the work switch to increase the engine speed from the idling speed to the working speed. (2) When the engine speed that has reached the working speed fluctuates outside the working threshold range corresponding to the working speed, the engine speed is set to the working threshold value. A control signal for automatically shifting within the range is output to the throttle control motor. When the engine does not include an idle screw, the controller 1 outputs a control signal for maintaining the engine speed at the idling speed when not working to the throttle control motor, whereby the engine speed is determined by the idling speed. It can be held normally. The controller 1 also outputs a control signal for lowering the engine speed from the working speed to the idling speed to the throttle control motor when the operator switches the work switch.

  Note that since the object of the present invention is to maintain the engine load state during work, it is easily understood by those skilled in the art that the “lower threshold value” must be set higher than the “driving threshold value”. obtain. That is, the “working threshold value” can be appropriately set based on a driving threshold value that is specific to the engine used.

  Even if the operator turns off the main switch 2 after turning off the work switch 3, the controller 1 immediately reduces the engine speed to below the driving threshold based on the off information of the preceding work switch 3. Then, based on the off information of the main switch 2, the stop switch relay 9 is operated to stop the engine 23.

  Even if the operator turns off the main switch 2 without turning off the work switch 3, the controller 1 immediately sets the engine speed to the driving threshold based on the off information of the main switch 2. Then, the stop switch relay 9 is operated to stop the engine 23.

  Therefore, when the worker turns off the work switch 3 or the main switch 2, the controller 1 drives the throttle control motor 8 so that the engine speed immediately drops below the driving threshold value, and the engine speed is the driving speed. If the main switch 2 is turned off when it is detected that it is less than the threshold value, the stop switch relay 16 is operated so as to stop the engine 23.

  The control flow in the engine speed automatic control means 100 will be described with reference to the flowchart shown in FIG.

  When the operator turns on the main switch 2, the controller 1 starts control (step S1). When the engine is started, the work switch 3 is off, so that the engine rotation is an idling rotation. In addition, the engine pulse from the ignition coil conducting wire 5 is continuously input to the controller 1 from the start to the end of the control.

  The controller 1 determines whether or not the engine speed is 0 (step S2), and ends the control if the engine has not been started successfully (step S3). If the controller 1 determines in step S2 that the engine is operating normally, the controller 1 proceeds to step S4 and determines whether the main switch 2 and the work switch 3 are on or off.

  Since the work switch is off before the work is started, the controller 1 determines that the throttle opening is the idling position (step S8). Next, the controller 1 detects that the main switch 2 is turned on (step S9), and then drives the throttle control motor 8 so that the throttle opening maintains the idling position (step S10). When it is detected in step S9 that the main switch 2 is turned off for some reason, the controller 1 operates the stop switch relay to stop the throttle control motor (step S11), and controls when the engine speed becomes zero. Ends (step S3).

  When the work switch 3 is turned on, the controller 1 determines YES in step S4 and proceeds to step S5, where the throttle control is performed based on the deviation between the working rotational speed and the idling rotational speed obtained from the multistage switch 4. An operation amount (motor operation amount) to drive the motor is calculated. Further, when the operation amount correction setting switch 7 is turned on, the controller 1 corrects the calculated operation amount (step S6), and drives the throttle control motor in accordance with the corrected operation amount (step S6). S7). As a result, the engine speed increases to the set value in the multistage switch 4.

  When the engine speed decreases below the lower limit threshold due to the load on the rotary blade 22 generated during work, the controller 1 performs steps S5 to S7 to drive the throttle control motor so as to maintain the engine speed at the work speed. Execute. As a result, the engine speed automatically keeps the desired working speed. When the rotary blade 22 is released from the load and the engine speed exceeds the upper threshold, the controller 1 performs steps S5 to S7 to drive the throttle control motor so as to maintain the engine speed at the work speed. This is executed to reduce the drive of the throttle control motor 8. As a result, the engine speed can be automatically maintained at a desired working speed.

  When the work switch 3 is turned off by the worker who has finished the work, the controller 1 that has determined NO in step S4 proceeds to step S8, and determines whether or not the engine speed is less than the driving threshold value. Here, when the controller 1 detects that the engine speed is equal to or higher than the driving threshold value, the controller 1 drives the throttle control motor 8 so as to decrease the engine speed (step S12).

  If it is detected that the engine speed has decreased below the driving threshold after the work switch 3 is turned off, the controller 1 determines whether the main switch is on or off (step S9). When the main switch is on, the controller 1 drives the throttle control motor 8 so that the throttle opening maintains the idling position (step S10). When the main switch is off, the controller 1 operates the stop switch relay. Then, the throttle control motor is stopped (step S11), and the control is finished after the engine speed becomes zero (step S3).

  If the main switch 2 is turned off even though the work switch 3 is on, the controller 1 that has detected the information in step S4 proceeds to step S8 and quickly performs the control as described above. .

  Since the brush cutter 200 according to the present embodiment includes the engine speed automatic control means 100 that performs the control as described above, control is performed so as to keep the engine speed constant according to the load variation on the rotary blade 22. Has been. Further, since the brush cutter 200 according to the present embodiment includes the engine speed automatic control means 100 that performs the control as described above, the operator switches the main switch 2 while the engine speed is the working speed. Even if the power is turned off, the engine 23 is controlled to stop without damaging the brush cutter components.

  Next, a second embodiment of the engine speed automatic control means mounted on the brush cutter 200 according to this embodiment will be described with reference to FIGS.

  FIG. 6 shows a functional block diagram of the engine speed automatic control means 101 according to the present invention. As shown in FIG. 6, the engine speed automatic control means 101 is similar to the engine speed automatic control means 100 according to the first embodiment, and includes the main switch 2, the work switch 3 and the multistage switch 4, and the controller 1. It has an ignition coil lead 5, an idle position detection sensor 6, an operation amount correction setting switch 7, a throttle control motor 8, a stop switch relay 9, and a capacitor 10. Therefore, even if the brush cutter 200 equipped with the engine speed automatic control means 101 does not have a power source, the engine speed automatic control means 101 can exhibit a desired control function.

  In the present embodiment, as in the first embodiment, the controller 1 has a configuration having a plurality of functional parts such as a calculation unit and a storage unit. In the controller 1, the arithmetic unit executes a program stored in the storage unit, and controls peripheral circuits such as an input / output circuit (not shown), thereby realizing control. As the peripheral circuit, a storage unit for storing various set values (for example, idling rotation speed, driving threshold, working threshold, etc.), an actual engine rotation value calculated by the calculation unit, and a stored value are stored. Examples include, but are not limited to, a circuit connecting between a comparison unit to be compared and a control unit for controlling the throttle control motor according to a value calculated by the calculation unit based on the comparison result. All of these functional blocks are controlled by the calculation unit, and the specific configuration, function, and the like of these functional blocks are not particularly limited.

  When the brush cutter 200 according to the present embodiment does not have a power source, an operator starts the engine 23 with a starter (not shown) and current is generated in the ignition coil. Therefore, even if it does not have a power source, the engine speed automatic control means 101 can be made to function and be throttled by storing and using the current slightly discharged from the ignition coil in the capacitor 10 connected to the ignition coil conductor 5. A current sufficient to drive the control motor 8 can be supplied. Further, the main switch 2 need only have an off function without an on function.

  The control flow in the engine speed automatic control means 101 will be described with reference to the flowchart shown in FIG.

  When the storage of the capacitor 10 (step S14) and the subsequent power supply (power generation) (step S15) from the capacitor 10 are started as the engine starts (step S13), the control of the engine speed automatic control means 101 starts ( Step S16). The control by the controller 1 is performed in the same manner as the engine speed automatic control unit 100 according to the first embodiment until the control ends (step S18) (first steps corresponding to steps S1 to S11 in the first embodiment). Steps S16 to S27 in the second embodiment). When the control of the engine speed automatic control means 101 is started, engine pulses are continuously input to the controller 1 via the ignition coil conductor 5. The controller 1 always calculates the engine speed based on the input engine pulse.

  When the brush cutter 200 according to the present embodiment does not have a power source, the number of engine pulses> 0 unless the main switch 2 is turned off. Therefore, the controller 1 is input with “the number of engine pulses that is not 0”. Thus, the above-described “main switch 2 is on” state is recognized.

  Further, a line for connecting the capacitor 10 and the ignition coil conductor 5 may be branched from the ignition coil conductor 5. The ignition coil conductor connected to the capacitor is more preferably a primary conductor.

  The power generation from the ignition coil is weak, but by reducing the size of the throttle control motor that requires the most power supply, the engine speed automatic control means 101 can be used even when power is supplied from a small capacity capacitor. Can be controlled.

  Although the case where the engine-driven work tool according to the present invention is a portable brush cutter has been described as an example, an engine-driven work tool that reduces work efficiency due to a load generated in the work site during work ( Those skilled in the art who have read this specification will easily understand that the technology of the present invention can be applied to a lawn mower or a grinder, for example.

  In each of the above-described embodiments, each member constituting the engine-driven work device according to the present invention is such that “calculation means such as a CPU executes a program code stored in a recording medium such as a ROM or a RAM. Although the case where the “function block is realized” is described as an example, it may be realized by hardware that performs the same processing. Further, it can also be realized by combining hardware that performs a part of the processing and the above arithmetic means that executes the program code that performs control of the hardware and the remaining processing. Further, even among the members described above as hardware, the hardware for performing a part of the processing and the arithmetic means for executing the program code for performing the control of the hardware and the remaining processing It can also be realized by combining them. The arithmetic means may be a single unit, or a plurality of arithmetic means connected via a bus inside the apparatus or various communication paths may execute the program code jointly.

  A person skilled in the art who has read the description of the present specification can easily modify various control methods (for example, proportional / integral / derivative control (PID control), etc.) known in the art to implement the present invention. Easily understand what you can do.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  The present invention is a technique that can be widely used in the field of using an engine-driven work tool. For example, in the field of a brush cutter, a lawn mower, or a pulverizer, particularly in the field of a portable brush cutter, the user-friendly Technology greatly helps further product development.

FIG. 1 shows an embodiment of the present invention, and is a block diagram showing a main configuration of an engine speed automatic control means according to the present invention. FIG. 2 is a flowchart showing the flow of control in the engine speed automatic control means shown in FIG. FIG. 3 is a perspective view showing a configuration of a brush cutter according to an embodiment of the present invention. FIG. 4 is a front view (A) and a side view (B) showing an embodiment of the multistage switch in the brush cutter shown in FIG. 3. FIG. 5 is a front view (A) and a side view (B) showing one embodiment of a work switch in the brush cutter shown in FIG. FIG. 6 shows an embodiment of the present invention, and is a block diagram showing a main configuration of the engine speed automatic control means according to the present invention. FIG. 7 is a flowchart showing the flow of control in the engine speed automatic control means shown in FIG. FIG. 8 is a perspective view showing a configuration of a conventional brush cutter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Controller 2 Main switch 3 Work switch 4 Multistage switch 5 Ignition coil conducting wire 6 Idle position detection sensor 7 Operation amount correction setting switch 8 Throttle control motor 9 Stop switch relay 10 Box 11 Capacitor 21 Cover tube 22 Rotary blade 23 Engine 24 Handle 25 Grip 26 Throttle operating lever 27 Wire 100 Automatic engine speed control means 101 Automatic engine speed control means 200 Engine-driven work tool (brusher) according to an embodiment of the present invention
300 Conventional brush cutter

Claims (9)

Outputs a work switch for switching between engine speed during work and engine speed during non-work, a throttle control motor for controlling the throttle opening, and a control signal for controlling the drive of the throttle control motor An engine-driven work implement having engine speed control means with a controller for
The controller
The operator outputs a control signal for increasing the engine speed from the idling speed to the working speed by switching the work switch to the throttle control motor,
When the engine rotational speed that has reached the working rotational speed fluctuates outside the working threshold range corresponding to the working rotational speed, the engine rotational speed is automatically shifted within the working threshold range. An engine-driven work implement characterized in that a control signal for output is output to a throttle control motor. The controller is
During the period when the control is performed in the engine speed control means, the engine speed is always calculated based on the engine pulse input via the ignition coil lead wire,
If the calculated engine rotational speed is outside the working threshold range corresponding to the working rotational speed, the motor operation amount necessary to shift the engine rotational speed within the working threshold range is calculated. Calculate
2. The engine-driven work tool according to claim 1, wherein a signal representing the motor operation amount is output to a throttle control motor.   2. The engine-driven work tool according to claim 1, further comprising a multistage switch for switching a plurality of work rotation speeds.   2. The engine drive according to claim 1, wherein the controller controls the throttle control motor based on an input signal indicating that the work switch or the main switch is OFF so as to reduce the engine speed to be less than a drive threshold value. Type work implement.   The said controller operates the stop switch relay which stops an engine, when an engine speed is less than a drive threshold value and the main switch of an engine drive type work implement is OFF. Engine-driven work equipment.   2. The engine drive according to claim 1, wherein the engine speed control means includes an idling position detection sensor that detects whether or not a throttle opening is an idling position and outputs a detection signal to the controller. Work tools.   The engine-driven work tool according to claim 2, wherein the ignition coil lead wire is connected to a capacitor, and the capacitor is used as a power source for the engine speed control means.   2. The engine-driven work device according to claim 1, wherein the work device is a brush cutter, a lawn mower, or a pulverizer. 2. The engine-driven work tool according to claim 1, wherein the work tool is a portable brush cutter.

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