JP2013050042A - Engine rotation speed control device for working machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent breakage of a working machine by suppressing an output of an engine during a high-load operation, in an engine rotation speed control device for maintaining a rotation speed of an engine at a set rotation speed.SOLUTION: This engine rotation speed control device for a working machine maintains a rotation speed of an engine at a set rotation speed independently of a work load. When the rotation speed of the engine is lowered due to the work load, a speed-increasing output is performed for recovering the rotation speed of the engine to the set rotation speed. After the speed-increasing output, when the rotation speed of the engine is not recovered to the set rotation speed even after the passage of a predetermined time, the set rotation speed is reset by performing subtraction processing of the set rotation speed by a predetermined amount. The subtraction amount for the re-setting is determined in accordance with a difference between the set rotation speed before the re-setting and the current engine rotation speed.

Description

  The present invention relates to an engine rotation speed control device for a working machine such as a combine.

Conventionally, a working machine such as a combine has a problem that efficiency and accuracy of work are reduced when the rotational speed of the engine is reduced due to a work load.
In particular, in the combine, when the rotational speed of the engine is reduced, the rotational speed of the handling cylinder and the swinging speed of the swing sorting device are lowered, which causes a problem that proper threshing and sorting operations cannot be performed.

  For this reason, conventionally, an engine rotation speed control device is provided that outputs a speed increase to return the rotation speed of the engine to the set rotation speed when the rotation speed of the engine decreases due to a work load.

As such a technique, an engine rotation speed control technique as shown in Patent Document 1 has been tried.
That is, the rotational speed to be controlled is fixedly set, and when the engine rotational speed is reduced due to the work load, the engine speed is output to the throttle operating section, and the rotational speed of the engine is set to this set rotational speed. To try to maintain.

Japanese Patent No. 3516303

  However, in the engine rotational speed control technology described in Patent Document 1, since the rotational speed that is the control target is fixedly set, for example, a high load that reaches the limit of the threshing processing capacity of the combine threshing device At the time of work, forcibly returning the rotational speed of the engine to the set rotational speed may cause clogging of processed products and damage to the mechanism in the threshing apparatus.

  An object of the present invention is to avoid breakage while maintaining the work efficiency of a work machine.

In order to solve the above-mentioned problems, the present invention takes the following technical means.
That is, the invention according to claim 1 is an engine rotation speed control device for a working machine that maintains the engine rotation speed at a set rotation speed regardless of the work load, and the engine rotation speed is reduced by the work load. If the engine speed does not return to the set speed even after a predetermined time has elapsed after the speed increase output, the engine speed is increased to return the engine speed to the set speed. The engine rotational speed control device of the working machine is characterized in that the set rotational speed is subtracted by a predetermined amount and reset.

  According to a second aspect of the present invention, the working machine according to the first aspect is configured such that a subtraction amount for the resetting is determined in accordance with a difference between the set rotational speed before the resetting and a current engine rotational speed. This is an engine rotation speed control device.

  According to a third aspect of the present invention, there is provided an engine rotational speed control device for a working machine according to the first aspect, wherein a subtraction amount for resetting is determined according to a vehicle speed when the set rotational speed is reset. It is a thing.

  According to a fourth aspect of the present invention, the set rotational speed is reset in a stepwise manner by performing a subtraction process at a constant rotational speed every predetermined time based on the determination of the subtraction amount. An engine rotation speed control device for a working machine according to claim 3 is provided.

  According to a fifth aspect of the present invention, the set rotational speed is reset in a stepwise manner by performing a subtraction process at a constant rotational speed for each predetermined travel distance based on the determination of the subtraction amount. Alternatively, an engine rotation speed control device for a working machine according to claim 3 is provided.

  According to a sixth aspect of the present invention, any one of the first to fifth aspects is configured such that, when the set rotational speed to be reset becomes equal to or lower than a predetermined rotational speed, the resetting of the set rotational speed is prohibited. An engine rotation speed control device for a working machine according to claim 1 is provided.

  The invention according to claim 7 is configured to automatically stop the engine when the set rotational speed to be reset becomes a predetermined rotational speed or less. This is an engine rotation speed control device for the working machine described.

  According to the first aspect of the present invention, when the rotational speed of the engine is reduced due to the work load, the speed-up output is performed so as to return the speed of the engine to the set speed. If the engine speed does not return to the set speed even after a lapse of time, the engine speed at high loads can be reduced by subtracting this set speed by a predetermined amount and resetting. Breakage can be prevented.

  According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, the subtraction amount for resetting is set according to the difference between the set rotational speed before resetting and the current engine rotational speed. By deciding, it is possible to prevent the working machine from being damaged by suppressing the output of the engine while suppressing a decrease in work efficiency.

  According to the invention described in claim 3, in addition to the effect of the invention described in claim 1, the work efficiency is determined by determining the subtraction amount for resetting according to the vehicle speed when resetting the set rotational speed. It is possible to prevent the working machine from being damaged by suppressing the output of the engine while suppressing the decrease of the engine.

  According to the invention described in claim 4, in addition to the effect of the invention described in claim 1, 2 or 3, the subtraction process is performed by subtraction processing at a constant rotational speed every predetermined time based on the determination of the subtraction amount. By resetting the rotation speed stepwise, it is possible to reduce a decrease in work efficiency while preventing breakage of the work machine.

  According to the invention described in claim 5, in addition to the effect of the invention described in claim 1, 2 or 3, the subtraction processing is performed at a constant rotational speed for each constant travel distance based on the determination of the subtraction amount. By resetting the set rotational speed in stages, it is possible to reduce the decrease in work efficiency while preventing the work machine from being damaged.

  According to the invention described in claim 6, in addition to the effect of the invention described in any one of claims 1 to 5, when the set rotational speed to be reset becomes a predetermined rotational speed or less, By prohibiting resetting of the set rotational speed, it is possible to prevent an excessive decrease in the engine rotational speed and to reduce a decrease in work efficiency.

  According to the invention described in claim 7, in addition to the effect of the invention described in any one of claims 1 to 6, when the set rotational speed to be reset becomes a predetermined rotational speed or less, the engine By automatically stopping, the traveling of the work machine can be stopped to prevent damage.

Combine side view Top view of the combine Block circuit diagram of engine speed controller flowchart Graph showing the relationship between vehicle speed and target engine speed Graph showing the relationship between time and target engine speed Graph showing the relationship between mileage and target engine speed Block diagram of the discharge cylinder turning control circuit

The embodiment of the present invention will be described by exemplifying a self-removing combine.
(Airframe configuration)
As shown in FIGS. 1 and 2, the combine is provided with a traveling device 2 below the body frame 1, a threshing device 3 is mounted on the upper left side of the body frame 1, and a grain is placed on the upper right side of the body frame 1. A storage device 4 is mounted, an electronic governor type or common rail fuel injection type engine E is mounted on the front side of the grain storage device 4 on the machine body frame 1, and a cutting device 5 is provided in front of the traveling device 2. Configure.

  Although the configuration of the traveling device 2 will be described later, a mission case 6 that is driven from the engine E via a hydrostatic continuously variable transmission (not shown) is attached to the front portion of the body frame 1. The crawler 9 is wound around the left and right drive wheels 7 and a large number of rolling wheels 8. The hydrostatic continuously variable transmission is provided with a mechanism that switches the swash plate angle on the hydraulic motor side to two positions and shifts the output in two stages.

  The threshing device 3 includes an upper handling chamber 3a in which a handling cylinder, a second processing cylinder, a dust processing cylinder, a dust exhaust fan are installed, a swing sorting shelf, a red pepper, a first transfer spiral, and a second transfer spiral. The lower sorting chamber 3b is configured to have a pinch facing the upper side of the feed chain on the outer side of the handling chamber 3a.

The grain storage device 4 is formed in a box-shaped container, and a base portion of the discharge cylinder 11 is connected to an upper end portion of a swivelable cerealing cylinder 10 erected on the rear side so as to be rotatable up and down.
The reaping device 5 supports a rear end portion of the vertical support frame 12 on the front portion of the body frame 1 so as to be pivotable up and down, and a left and right intermediate portion of the lower gear case 13 in the left and right direction is supported on the front end portion of the vertical support frame 12. A clipper-type cutting blade 15 in the left-right direction is attached to an intermediate part of the weeding frame 14 that is connected and fixed to the front side of the lower gear case 13, and a lower part of the pulling device 16 is attached to the front part of the weeding frame 14. The weed body 17 is attached to the front end of the frame 14.

  The threshing device 3 is driven from the output shaft of the engine E via a tension clutch type threshing clutch, and the reaping device 5 is driven from the intermediate output shaft of the transmission case 6 via a tension clutch type reaping clutch. The configuration. The threshing clutch and the mowing clutch are operated by electric motors provided respectively. Note that the reaping device 5 may be driven to change speed via a hydrostatic continuously variable transmission for driving the reaping device driven by the engine E.

A pilot seat is mounted on the upper part of the engine cover that surrounds the engine E, and a steering lever for steering the traveling aircraft and raising and lowering the reaping device 5 is provided in front of the pilot seat. A shifting lever that shifts the traveling speed by shifting the hydrostatic continuously variable transmission, and a cutting and threshing clutch lever that connects and disconnects transmission of driving force to the reaping device 5 and the threshing device 3. Is covered with a cabin 18.
(Overall configuration of engine speed control device)
As shown in FIG. 3, the engine speed control device 19 has a cutting clutch switch 21 that detects the connection / disconnection state of the cutting clutch, and a threshing on the input side of the engine controller 20 surrounded by a one-dot chain line. Threshing clutch switch 22 for detecting the clutch connection / disconnection state, cutting / threshing position sensor 23 for detecting the operating position of the cutting / threshing clutch lever, traveling shift position sensor 24 for detecting the operating position of the shift lever, and transmission case 6 A vehicle speed sensor 25 that detects the vehicle speed from the rotation speed of the inner transmission shaft and an engine rotation speed sensor 26 that detects the drive rotation speed of the engine E are connected.

On the output side of the engine controller 20, a speed increasing solenoid 27 that increases the fuel supply amount to the engine E to increase the output rotation speed of the engine E, and a fuel supply amount to the engine E are decreased. A decelerating solenoid 28 for decelerating the output rotation speed of the engine E and an engine stop solenoid 29 for stopping the fuel supply to the engine E and stopping the engine E are connected.
(Engine controller configuration)
The engine controller 20 inputs a digital signal input processing circuit 31, an analog signal input processing circuit 32, and a pulse input processing circuit 33 to a core engine speed control instruction circuit 30, and a timer count processing circuit 34 is connected. And the travel distance count circuit 35 are connected to each other, and an engine acceleration output processing circuit 36, an engine deceleration output processing circuit 37, and an engine stop output processing circuit 38 are connected in output.

  The mowing clutch switch 21 and the threshing clutch switch 22 are connected to the input side of the digital signal input processing circuit 31, and the mowing threshing position sensor 23 and the traveling shift position sensor 24 are connected to the input side of the analog signal input processing circuit 32, The vehicle speed sensor 25 and the engine speed sensor 26 are connected to the input side of the pulse input processing circuit 33.

The acceleration solenoid 27 is connected to the output side of the engine acceleration output processing circuit 36, the deceleration solenoid 28 is connected to the output side of the engine deceleration output processing circuit 37, and the engine stop solenoid 29 is output from the engine stop output processing circuit 38. Connect to the side.
(Control flow)
The flow of control with the above configuration will be described.

  First, in order to maintain the engine rotation speed at the set rotation speed, the engine speed control as a precondition is that when the engine rotation speed decreases from the set rotation speed due to an increase in load, the above-described speed increasing solenoid 27 is applied. The engine speed is increased by the output. On the other hand, when the engine rotational speed increases from the set rotational speed due to the decrease in the load, the engine rotational speed is decelerated by the output to the deceleration solenoid 28 described above.

In the control that is the premise, the following processing is performed.
That is, in the flowchart of FIG. 4, with the engine E started, it is checked from the detected value of the cutting / threshing position sensor 23 whether the cutting / threshing clutch lever is operated to the clutch connection position, and this is operated to the clutch connection position. When it is determined that the cutting clutch switch 21 is ON, it is checked whether or not the cutting clutch switch 21 is ON.

  Then, it is checked whether or not the cutting clutch switch 21 is ON. If it is determined that the cutting clutch switch 21 is ON and the cutting clutch is connected, the shift lever is moved to a position other than the neutral range by the traveling shift position sensor 24. That is, it is determined whether or not the vehicle is operating in the forward or reverse operation range.

  When it is determined that the shift lever is operated to a position other than the neutral range, the detected value from the engine speed sensor 26 is checked, and the engine speed is lower than a predetermined value set in advance. In this case, when the low-speed driving state continues for a predetermined time, the set rotational speed, which is the target value of the engine rotational speed control, is subtracted by a predetermined amount and reset, and the engine rotational speed control that is the above-mentioned assumption is performed. To do.

  In the above-described ON / OFF determination of the reaping clutch switch 21, when it is determined that the reaping clutch switch is not ON, the threshing clutch switch 22 is determined to be ON / OFF. The process proceeds to shift lever position determination by the shift position sensor 24.

  If it is determined by the shift lever position determination that the shift lever is in the neutral range, the vehicle speed detected by the vehicle speed sensor 25 is checked. If the vehicle speed corresponds to the forward running state, The process proceeds to the determination of the engine speed described above.

  Further, in the determination of the engine rotation speed described above, when it is determined that the detected engine rotation speed is a low speed state to be stopped, the engine E is stopped by the output to the engine stop solenoid 29.

Further, when the low-speed driving state of the engine E is completed within a predetermined time, the set rotational speed that is the target value is not reset.
As described above, when the engine speed decreases due to the work load, the engine speed is increased to return the engine speed to the set speed, and the engine is output even after a predetermined time has elapsed after the increased speed output. If the rotation speed does not return to the set rotation speed, the preset rotation speed is subtracted by a predetermined amount and reset, thereby suppressing engine output at high loads and preventing damage to the work equipment. it can.

  In addition, by determining the subtraction amount for resetting according to the difference between the set rotational speed before resetting and the current engine speed, the engine output can be suppressed while reducing the work efficiency. It is possible to prevent the work machine from being damaged.

  In addition, as shown in FIG. 5, if the configuration is such that the subtraction amount for resetting is determined according to the vehicle speed when resetting the set rotational speed, the output of the engine can be reduced while suppressing a reduction in work efficiency. It is possible to prevent the working machine from being damaged.

  Further, as shown in FIG. 6, if the configuration is such that the set rotational speed is reset in a stepwise manner by subtracting a constant rotational speed at regular time intervals based on the determination of the subtraction amount, the rotational speed of the engine E is reduced. By gradually lowering it, it is possible to reduce a decrease in work efficiency while preventing damage to the work machine.

  Further, as shown in FIG. 7, if the configuration is such that the set rotational speed is reset stepwise by subtracting a constant rotational speed for each constant travel distance based on the determination of the subtraction amount, the rotational speed of the engine E The work efficiency can be reduced while decreasing the work efficiency while preventing the work machine from being damaged.

  In addition, when the set rotational speed to be reset is less than or equal to the predetermined rotational speed, prohibiting the resetting of the set rotational speed prevents an excessive decrease in the engine rotational speed and reduces the work efficiency. Can be reduced.

Further, when the set rotational speed to be reset becomes equal to or lower than the predetermined rotational speed, the engine is automatically stopped, so that the traveling of the work implement can be stopped and damage can be prevented.
(Discharge cylinder turning control)
An electric motor for rotating the cereal cylinder 10 about the vertical axis (internal spiral axis) and a hydraulic cylinder for rotating the discharge cylinder 11 up and down with respect to the cereal cylinder 10 are provided. It is set as the structure which turns the discharge cylinder 11 by rotating to the center. Further, the discharge cylinder 11 is divided and fitted into a base-side cylinder and a tip-side cylinder, and the tip-side cylinder is moved in the longitudinal direction with respect to the base-side cylinder by driving of the telescopic electric motor. By making it slide, the discharge cylinder 11 is configured to be extendable. That is, in the discharge cylinder 11, a hexagonal shaft, in which a large number of divided spiral bodies are freely slidable in the longitudinal direction, is provided so as to be extendable and retractable with respect to a hollow spiral shaft attached with a continuous spiral. Moreover, the electric motor for discharge | emission which turns on and off the discharge clutch which drives the discharge spiral incorporated in the cereal cylinder 10 and the discharge cylinder 11 is provided.

  Then, as shown in FIG. 8, on the input side with respect to the auger controller 39, the discharge cylinder rising signal (a) and the discharge cylinder lowering signal ( b), discharge cylinder left turn signal (c), discharge cylinder right turn signal (d), discharge cylinder extension signal (e), discharge cylinder shortening signal (f), and discharge drive start / stop signal ( g), a discharge tube automatic storage / extension signal (h), and a discharge tube emergency stop signal (i). The receiver 40 receives a signal from the remote control device 42 and outputs it to the received voltage signal processing circuit 41.

  Further, on the output side of the auger controller 39, a discharge cylinder raising solenoid 43 that extends the hydraulic cylinder, a discharge cylinder lowering solenoid 44 that shortens the hydraulic cylinder, and a discharge cylinder left-turning relay that drives the electric motor to rotate forward. 45, a discharge cylinder right turn relay 46 for driving the electric motor in reverse, an extension side relay 47 for driving the extension motor to the extension side, and a reduction side relay 48 for driving the extension motor to the reduction side, The discharge clutch connection side relay 49 for connecting the discharge clutch by rotating the discharge electric motor forward and the discharge clutch disconnecting side relay 50 for disconnecting the discharge clutch by rotating the discharge electric motor reversely are connected.

  The auger control controller 39 has a digital signal input processing circuit 52 for inputting the signals (a) to (i) on the input side of the auger turning control circuit 51 as a core, and an analog signal input process. The circuit 53 and the pulse input signal processing circuit 54 are connected. Further, on the output side of the auger turning control circuit 51, an auger ascent / descent output processing circuit 55 for outputting to the discharge cylinder raising solenoid 43 and the discharge cylinder lowering solenoid 44, the discharge cylinder left turning relay 45, and the discharge cylinder right turning. An auger motor output processing circuit 56 that outputs to the rotation relay 46, the extension side relay 47, and the shortening side relay 48, and a discharge clutch output processing circuit 57 that outputs to the discharge clutch connection side relay 49 and the discharge clutch disconnection side relay 50 are connected. Further, a timer count processing circuit 58 is connected to the auger turning control circuit 51 so as to be able to communicate with each other.

  With the above configuration, the radio signal output by the operation of the remote operation device 42 is received by the receiver 40, and the discharge cylinder 11 is swung, moved up and down, expanded and contracted, and discharged, but the operation of the remote operation device 42 is performed. After the signal for automatically turning the discharge tube 11 is received by the receiver 40, the turning of the discharge tube 11 is automatically stopped when the reception state of the signal from the remote control device 42 becomes defective. And

Alternatively, a configuration may be adopted in which, when this reception state failure is detected, the turning operation is continued until a predetermined automatic turning position is continued.
Further, when a reception state failure is detected, the previous turning output is continued for a certain time, and when the receiving state is restored to a good state, the turning output is again performed according to the signal from the remote control device 42. It is good also as a structure.
(Engine automatic stop control)
The traveling pump hydrostatic continuously variable transmission has a structure in which the trunnion shaft of the hydraulic pump is rotationally controlled by an electric motor, and the electric motor is driven and controlled in accordance with a detection value of the traveling shift position sensor 24 of the shift lever. The configuration.

  Then, when the cutting and threshing clutch lever is operated to be cut off while the vehicle speed sensor 25 detects the running stop state, the engine E is automatically stopped and the speed change lever is operated to increase the speed from the neutral range or When the mowing and threshing clutch lever is connected, the engine E is automatically started. When the engine E is started by a speed increasing operation from the neutral range of the shift lever, the shift lever is once moved into the neutral range. Control of the electric motor by the traveling shift position sensor 24 is suppressed so that the hydrostatic continuously variable transmission does not output unless it is operated.

  That is, when the engine E is started based on the start operation by the shift lever, the vehicle starts running before the rotational speed of the engine E increases, so the hydrostatic continuously variable transmission or the engine E itself is overloaded, There is a problem that durability is remarkably lowered. Further, there is a problem that safety is lowered due to a sudden start due to an increase in the rotational speed of the pump of the hydrostatic continuously variable transmission accompanying the start of the engine E.

  On the other hand, according to the above-described configuration, when the engine E is started by the speed increasing operation from the neutral region of the shift lever, the stationary state is maintained, and after the shift lever is once returned to the neutral region, the hydrostatic type By permitting the output of the continuously variable transmission, sudden start can be prevented and safety can be improved.

  In addition, after the engine E is started by the speed increasing operation from the neutral range of the shift lever, the control of the electric motor by the traveling shift position sensor 24 is checked until the rotation speed of the engine E reaches a predetermined rotation speed. Good.

  In addition, when the engine E is started by the above-described operation of connecting the mowing and threshing clutch lever, the mowing clutch is electrically connected so that the mowing clutch and the threshing clutch are not connected unless the mowing and threshing clutch lever is once operated to the shut-off position. Check the operation of the motor and the electric motor for connecting the threshing clutch.

  That is, when the engine E is started based on the connection operation of the mowing and threshing clutch lever, the mowing device 5 and the threshing device 3 are driven before the rotational speed of the engine E is increased. There is a problem that the durability is remarkably lowered due to an overload state. In addition, as the engine E is started, the reaping device 5 and the threshing device 3 are rapidly driven, and there is a problem that safety is lowered.

  On the other hand, according to the above-described configuration, when the engine E is started by the connection operation of the mowing and threshing clutch lever, the working machine is stopped and the mowing and threshing clutch lever is once returned to the shut-off position. By permitting the connection of the mowing clutch and the threshing clutch, it is possible to prevent the working machine from being suddenly driven and to enhance the safety.

After the engine E is started by the operation of connecting the mowing and threshing clutch lever, the operation of the electric motor for connecting the mowing clutch and the electric motor for connecting the threshing clutch is suppressed until the rotational speed of the engine E reaches a predetermined rotational speed. It is good also as composition to do.
(Exhaust tube expansion / contraction control)
A position sensor for detecting the expansion / contraction position of the discharge cylinder 11 (sliding position of the front end side cylinder relative to the base side cylinder) is provided, and an operation output to the shortening side is output to the expansion / contraction electric motor over a certain period of time. However, when the detection value of the position sensor does not change, it is determined that the grain is compressed between the split spirals in the discharge cylinder 11, and the detection value of the position sensor at this time is used as a stored value. Remember. In the next discharging operation, the stored value is compared with the detected value of the current position sensor, and the connection of the discharging clutch is permitted only when the detected value at the current time is on the extension side with respect to the stored value. To do. Further, when an operation for connecting the discharge clutch is performed in a state where the connection of the discharge clutch is prohibited, a buzzer output and a display output to the monitor may be made to notify the operator.

With this configuration, it is possible to prevent the split spiral body from being damaged by the compression of the grains in the discharge cylinder 11.
(Alignment assist control)
Cameras that image the front are installed at the right end and the left end of the reaping device 5, and the boundary line is determined from the contrast in the image while constantly analyzing the image from the left camera, and this boundary line is constant. This boundary line is determined to be the end of the planted culm when it has an angle and moves through the angle of view at a constant speed. Then, when the end of the planted culm is determined from the image of the left camera after detecting turning over a predetermined time without the planted culm in front of the reaping device 5, the determined planting Rotation control is performed so that the end of the cereal pod is aligned with the right side pod. Subsequently, when the end of the planted culm is determined from the image of the right camera, turning control is performed so that the right end weed stalk is aligned with the determined end of the planted culm.

As a result, it is possible to automatically turn around the headland.
In addition, after the turning control described above, when the boundary line in the image coincides with the line set in the angle of view and the line is recognized to the full lower side (front side of the machine), the reaping device 5 is automatically You may comprise so that it may descend | fall.

  As a result, after turning the headland and aligning the planted culm again, when the planted culm approaches, the mowing device 5 can be automatically lowered to resume the mowing operation.

E Engine 19 Engine rotational speed control device 20 Engine control controller 21 Harvesting clutch switch 22 Threshing clutch switch 23 Harvesting / threshing position sensor 24 Traveling shift position sensor 25 Vehicle speed sensor 26 Engine rotational speed sensor 27 Acceleration solenoid 28 Deceleration solenoid 29 Engine stop solenoid 30 Engine rotation speed control instruction circuit 31 Digital signal input processing circuit 32 Analog signal input processing circuit 33 Pulse input processing circuit 34 Timer count processing circuit 35 Travel distance counting circuit 36 Engine acceleration output processing circuit 37 Engine deceleration output processing circuit 38 Engine stop output Processing circuit

Claims (7)

  An engine rotation speed control device for a working machine that maintains an engine rotation speed at a set rotation speed regardless of a work load. When the engine rotation speed decreases due to a work load, the rotation speed of the engine is set and rotated. If the engine speed does not return to the set speed even after a lapse of a predetermined time after the speed increase output, the set speed is subtracted by a predetermined amount. An engine rotation speed control device for a working machine, characterized in that it is configured to be reset again.   The engine rotational speed control device for a working machine according to claim 1, wherein a subtraction amount for resetting is determined according to a difference between the set rotational speed before resetting and the current engine rotational speed.   The engine rotational speed control device for a working machine according to claim 1, wherein a subtraction amount for resetting is determined according to a vehicle speed when resetting the set rotational speed.   4. The working machine according to claim 1, wherein the set rotational speed is reset stepwise by performing a subtraction process at a constant rotational speed every predetermined time based on the determination of the subtraction amount. Engine speed control device.   4. The working machine according to claim 1, wherein the set rotational speed is reset stepwise by performing a subtraction process at a constant rotational speed for each constant travel distance based on the determination of the subtraction amount. Engine speed control device.   The working machine according to any one of claims 1 to 5, wherein when the set rotational speed to be reset is equal to or lower than a predetermined rotational speed, the resetting of the set rotational speed is prohibited. Engine speed control device.   The engine rotation speed of the working machine according to any one of claims 1 to 6, wherein the engine is automatically stopped when the set rotation speed to be reset is equal to or lower than a predetermined rotation speed. Control device.

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