JP2020084794A - Portable engine work machine - Google Patents

Abstract

To provide a portable engine work machine capable of improving operability of acceleration.SOLUTION: A portable engine work machine (1) includes a control device (16) for controlling the rotational frequency by detecting the rotational frequency of an internal combustion engine (2). In a fast idle mode (M2), when a throttle valve (8) is in a fast idling position (8b), the internal combustion engine operates at the rotational frequency lower than predetermined clutch-in rotational frequency (R4), and when the throttle valve is operated to a full open position (8c), it operates at the rotational frequency higher than the predetermined clutch-in rotational frequency. In a normal idle mode (M3), when the throttle valve is in a full closed position (8a), the internal combustion engine operates at the normal idle rotational frequency. When the throttle valve is moved to the full open position (8c), the control device releases the normal idle mode and shifts to an acceleration mode (M4).SELECTED DRAWING: Figure 5

Description

The present invention relates to a portable engine working machine.

Portable engine working machines such as chainsaws, brush cutters and hedge trimmers are known.

Further, the engine working machine has an internal combustion engine, an operating portion (for example, a chain with a blade in the case of a chainsaw), and a centrifugal clutch arranged between the internal combustion engine and the operating portion. The centrifugal clutch connects the internal combustion engine and the operating part when the rotational speed of the internal combustion engine is higher than a predetermined clutch-in rotational speed, whereby the rotation of the internal combustion engine is transmitted to the operating part.

The internal combustion engine of an engine working machine is stable at a rotation speed lower than the clutch-in rotation speed (normal idle speed) when the carburetor throttle valve provided in the engine work machine is at or near the fully closed position (normal idle position). And is designed to rotate. This state is called an idle state (normal idle state).

When the internal combustion engine is started, especially in the case of insufficient warm-up, the throttle valve of the carburetor is supplied to the half-open position (fast idle position) in order to stabilize the startup and operation of the internal combustion engine. It is common practice to start an internal combustion engine with the amount of air to be increased increased, and to operate the engine while keeping the throttle valve in the half-open position for a while. This state is called the fast idle state.

The internal combustion engine may be controlled to maintain the rotational speed of the internal combustion engine at a rotational speed lower than the clutch-in rotational speed in the fast idle state and/or the normal idle state. In this case, the rotation speed of the internal combustion engine cannot be made higher than the clutch-in rotation speed unless such control for the fast idle state and/or the normal idle state is released. This is to prevent the internal combustion engine and the operating portion from being connected to each other when the operator does not intend or to stabilize the driving of the internal combustion engine by keeping the rotation speed constant. In this regard, a technique is known in which such control for the fast idle state is released after a predetermined time has passed and the normal idle state is set (see, for example, Patent Document 1).

Further, there is known a technique of using PI control aiming at a predetermined normal idle speed in the normal idle state (for example, refer to Patent Document 2).

U.S. Patent Application Publication No. 2008/0223339 U.S. Pat. No. 4,979,477

When performing control to keep the rotation speed constant due to the fast idle state and/or the normal idle state, the operator sets the throttle valve to the fully open position (acceleration position) to accelerate the internal combustion engine. In such a case, the responsiveness of acceleration of the internal combustion engine may deteriorate due to the control for maintaining the rotation speed constant.

Therefore, an object of the present invention is to provide a portable engine working machine with improved operability for acceleration.

In order to achieve the above object, a portable engine working machine according to the present invention comprises an internal combustion engine, an operating part driven by the internal combustion engine, a clutch arranged between the internal combustion engine and the operating part, and an internal combustion engine. A control device that detects the number of revolutions of the internal combustion engine and controls the number of revolutions of the internal combustion engine and the operating unit when the number of revolutions of the internal combustion engine is higher than a predetermined clutch-in number of revolutions. And transmitting the rotation of the internal combustion engine to the operating portion, the internal combustion engine having a fuel amount control unit including a throttle valve, an air amount control unit, and/or an air-fuel mixture control unit. After the engine is started, the operating mode of the internal combustion engine is configured to shift to the fast idle mode, and in the fast idle mode, the internal combustion engine is placed in a predetermined fast idle position in which the throttle valve is opened more than or near the fully closed position. For example, it is configured to operate at a rotational speed lower than a predetermined clutch-in rotational speed, and is configured to operate at a rotational speed higher than a predetermined clutch-in rotational speed when the throttle valve is at the fully open position, The control device is configured to shift the operating mode of the internal combustion engine to the normal idle mode after releasing the fast idle mode, and in the normal idle mode, the internal combustion engine does not have the throttle valve at or near the fully closed position. For example, when the throttle valve is configured to operate at the normal idle speed and the throttle valve is moved to the fully open position and the rotational speed of the internal combustion engine exceeds one boundary value of the predetermined rotational speed elements, the control device operates in the normal idle mode. Is released and the operating mode of the internal combustion engine is shifted to the acceleration mode.

The engine working machine configured as described above has a relatively high output that is configured such that the rotation speed of the internal combustion engine becomes higher than the predetermined clutch-in rotation speed when the throttle valve is fully opened in the fast idle mode. It is an engine working machine of. After the start of the internal combustion engine, when the throttle valve is in the predetermined fast idle position, the internal combustion engine operates at the fast idle speed, and the control device shifts the operation mode of the internal combustion engine to the fast idle mode. Since the fast idle rotation speed is set to be lower than the predetermined clutch-in rotation speed, the internal combustion engine and the operating unit are not connected to each other when the operator does not intend. On the other hand, by fully opening the throttle valve in the fast idle mode, the rotational speed of the internal combustion engine can be intentionally made higher than the predetermined clutch-in rotational speed. As a result, it is possible to promote warming up of the engine working machine. At this time, the operator can promote warming up by a simple operation of fully opening the throttle valve. Next, the control device releases the fast idle mode and shifts the operating mode of the internal combustion engine to the normal idle mode. When the throttle valve is at or near the fully closed position, the internal combustion engine operates at a normal idle speed lower than a predetermined clutch-in speed, and engine stall is also prevented at the same time. Next, in the normal idle mode, when the operator operates the throttle valve to the fully open position, the engine having a relatively high output causes the rotational speed of the internal combustion engine to rise sensitively, and the control device responds to it. The operation mode of the internal combustion engine can be quickly changed to the acceleration mode.

In the engine work machine described above, preferably, the control in the normal idle mode is feedback control aiming at the predetermined normal idle speed, and the feedback control is preferably PI control.

In the engine working machine configured as described above, in the normal idle mode, the operability of acceleration by the worker can be improved by the relatively high output engine while stabilizing the rotation speed by the feedback control.

In the above engine work machine, preferably, the control device performs feedback control targeting a predetermined fast idle speed in the fast idle mode, and the feedback control in the fast idle mode is preferably PI control.

In the engine working machine configured as described above, when the throttle valve is at the predetermined fast idle position, the rotation speed of the internal combustion engine is stabilized by the feedback control targeting the predetermined fast idle rotation speed. Further, if the operator fully opens the throttle valve during the fast idle mode, the engine speed of the internal combustion engine becomes higher than the predetermined clutch-in speed due to the relatively high-power engine, but the internal combustion engine is controlled by the feedback control. The engine speed can be suppressed within a safe range.

In the above engine working machine, the control device may release the fast idle mode after a predetermined period has elapsed from the start thereof, or may release it when the cumulative rotation amount from the start reaches a predetermined value. Alternatively, it may be canceled when the time integration of the number of revolutions from the start reaches a predetermined value.

In the engine working machine configured as described above, the warm-up of the internal combustion engine can be reliably performed by setting the predetermined period or the predetermined value to the period or the value at which the warm-up of the internal combustion engine is achieved. When the time integration of the integrated rotation amount or the rotation speed is adopted, the operator can easily increase the rotation speed of the internal combustion engine by intentionally opening the throttle valve fully during the fast idle mode. The warm air of the engine can be promoted. Therefore, since the engine has a relatively high output, it is possible to cancel the fast idle mode and shorten the time until the mode shifts to the acceleration mode, and improve the operability of acceleration by the operator. it can.

1 is a perspective view of a chainsaw according to the present invention. 1 is a schematic diagram of an internal combustion engine. 1 is a schematic diagram of an ignition device for an internal combustion engine. It is a circuit diagram of an ignition device. It is a figure which shows the 1st operation example of the chainsaw by this invention. It is a figure which shows the 2nd operation example of the chainsaw by this invention.

Hereinafter, a chainsaw that is a portable engine working machine according to an example of an embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, a chainsaw 1 includes an internal combustion engine 2, a bladed chain 3 that is an operating portion driven by the internal combustion engine 2, and a centrifugal clutch arranged between the internal combustion engine 2 and the bladed chain 3. Have four. The centrifugal clutch 4 connects the internal combustion engine 2 and the bladed chain 3 when the rotational speed of the internal combustion engine 2 is higher than a predetermined clutch-in rotational speed, and rotates the internal combustion engine 2 with the bladed chain 3. Communicate to. Further, the chainsaw 1 has a brake lever 5 that operates a brake (not shown) that stops the output side of the centrifugal clutch 4. The internal combustion engine 2, the bladed chain 3, the centrifugal clutch 4, and other structures in the chainsaw 1 are conventional and their detailed description is omitted.

As shown in FIG. 2, the internal combustion engine 2 is preferably a two-stroke gasoline engine. Further, the carburetor 7 provided in the internal combustion engine 2 has a throttle valve 8 that adjusts the amount of the air-fuel mixture that flows into the internal combustion engine 2. The throttle valve 8 is operated by a throttle lever 7a (see FIG. 1) or a choke knob (not shown) or the like, and is a conventionally known one. The internal combustion engine 2 has a cylinder 2a, a crankshaft 2b, a piston 2c arranged in the cylinder 2a and connected to the crankshaft 2b, and a spark plug 10 arranged above the cylinder 2a. In the compression stroke of the internal combustion engine 2, the piston 2c rises to the top dead center position 2d. Generally, at a timing before the piston 2c reaches the top dead center position 2d, the ignition plug 10 is effectively operated to burn the air-fuel mixture in the cylinder 2a, so that the downward thrust force is applied to the piston 2c. give.

As shown in FIG. 3, the internal combustion engine 2 has an ignition device 12 that operates the spark plug 10. The ignition device 12 includes a pair of magnets 14b provided on the outer circumference of a flywheel 14a attached to the crankshaft 2b (see FIG. 2) and a U-shaped iron core 14c arranged adjacent to the outer circumference of the flywheel 14a. And an input coil 14d wound around the iron core 14c. Further, the ignition device 12 has a control device 16 connected to the input coil 14d, a primary coil 18a connected to the control device 16, and a secondary coil 18b connected to the ignition plug 10. There is.

As shown in FIG. 4, the control device 16 of the ignition device 12 includes a microcomputer 20, a diode 22, a capacitor 24, and a switch thyristor 26. The pin a and the pin e of the microcomputer 20 are connected to the input coil 14d, and the voltage induced in the input coil 14d supplies power to the microcomputer 20. Pins b and c of the microcomputer 20 are also connected to the input coil 14d, and the microcomputer 20 receives the electrical signal induced in the input coil 14d. The diode 22, the capacitor 24, and the primary coil 18a are connected in series to the input coil 14d. The switch thyristor 26 is connected in parallel with the capacitor 24 and the primary coil 18a. The pin d of the microcomputer 20 is connected to the gate of the thyristor 26. When the pin d is LOW, the thyristor 26 is non-energized, and when the pin d is HIGH, the thyristor 26 is energized.

Next, the operation of the ignition device according to the example of the embodiment of the present invention will be described.

When the crankshaft 2b rotates due to the operation of the internal combustion engine 2, the pair of magnets 14b attached to the flywheel 14a passes near the U-shaped iron core 14c. As a result, a voltage is induced in the input coil 14d, and a current flows in the input coil 14d. The microcomputer 20 is driven by the voltage supplied from the input coil 14d via the pins a and e, and receives the electric signal by the current via the pins b and c. The microcomputer 20 detects or calculates the rotation speed (rotation speed) and the angular position of the internal combustion engine 2 based on the electric signal.

When the microcomputer 20 sets the pin d to LOW and brings the thyristor 26 into a non-conducting state, the capacitor 24 is charged by the voltage induced in the input coil 14d. At the ignition timing of the spark plug 10, the microcomputer 20 sets the pin d to HIGH to bring the thyristor 26 into an energized state. As a result, the capacitor 24 is discharged and a current flows through the primary coil 18a. The current flowing through the primary coil 18a causes a high voltage pulse to be generated in the secondary coil 18b, thus actuating the spark plug 10.

In the chainsaw 1 according to the example of the embodiment of the present invention, a sensor for detecting the position of the throttle valve 8 is not provided. The control device 16 (microcomputer 20) detects the rotational speed and the angular position of the internal combustion engine 2, thereby determining the position of the throttle valve 8, changing the operation mode, and controlling the ignition timing, as described later. Is programmed or configured to do the following. As shown in FIG. 2, the positions of the throttle valve 8 are, for example, a normal idle position 8a which is at or near the fully closed position, a fast idle position 8b which is a half open position, and an acceleration position 8c which is a fully open position. In this specification, the rotation speed of the internal combustion engine 2 when the throttle valve 8 is in the normal idle position 8a is referred to as a normal idle rotation speed, and the rotation speed of the internal combustion engine 2 when the throttle valve 8 is in the fast idle position 8b. Is referred to as the fast idle speed.

Next, with reference to FIGS. 5 to 6, first to second operation examples of the chainsaw 1 according to the embodiment of the present invention will be described.

In the first operation example shown in FIG. 5, the control device 16 shifts the operation mode of the internal combustion engine 2 in the order of the start mode M1, the fast idle mode M2, the normal idle mode M3, and the acceleration mode M4. The crankshaft 2b of the internal combustion engine 2 is rotated by pulling the recoil rope or the like to start the internal combustion engine 2.

In the starting mode M1, the control device 16 accelerates the internal combustion engine 2 using a map that defines the relationship between the rotation speed and the ignition timing. At time T1, control device 16 determines whether the rotation speed of internal combustion engine 2 is higher or lower than predetermined rotation speed R1. The predetermined rotation speed R1 and time T1 are preferably set so that it can be determined whether the throttle valve 8 is in the fast idle position 8b or the normal idle position 8a. T1 is, for example, 1 to 3 seconds, and the predetermined rotation speed R1 is, for example, 2500 to 3000 rpm.

In the first operation example, it is assumed that the throttle valve 8 is in the fast idle position 8b for warm-up operation, for example. In this case, the rotation speed of the internal combustion engine 2 becomes higher than the predetermined rotation speed R1 at the time T1. The control device 16 determines that the throttle valve 8 is in the fast idle position 8b by detecting that the rotation speed of the internal combustion engine 2 is higher than a predetermined rotation speed R1, and changes the operation mode from the start mode M1 to the fast idle mode. The mode is changed to M2.

In the fast idle mode M2, the control device 16 performs control such that a predetermined rotation speed R2 lower than the clutch-in rotation speed R4 is set as a target rotation speed of the internal combustion engine 2. This prevents the rotational speed of the internal combustion engine 2 from becoming higher than the clutch-in rotational speed R4 (for example, 4000 rpm) when the throttle valve 8 is in the fast idle position 8b. On the other hand, the invention of the present application is directed to the chainsaw 1 on which the internal combustion engine 2 having a relatively high output is mounted, and when the worker sets the throttle valve 8 to the fully open position 8c in the fast idle mode M2, the rotation of the internal combustion engine 2 The number is higher than a predetermined clutch-in rotation speed R4 and is maintained within a safe speed range (for example, 7,000 rpm or less which is a rotation speed limit R6). The control may be control using a map that defines the relationship between the rotation speed and the ignition timing, or may be feedback control that detects the rotation speed and changes the ignition timing. The feedback control is preferably PI control.

The fast idle mode M2 is not released until time T2. A first example of the time T2 is a time obtained by adding a predetermined period to the time T1. The predetermined period is preferably a period (for example, 5 to 10 seconds) to the extent that warming up of the internal combustion engine 2 is achieved. For example, in the fast idle mode M2, if the operator intentionally fully opens the throttle valve 8, the engine speed can be increased by the relatively high output engine, and the warm-up can be reliably performed within a predetermined period.

A second example of the time T2 is the time when the integrated rotation amount started from the time T1 reaches a predetermined value. The higher the rotation speed during the fast idle mode M2, the shorter the time required for the accumulated rotation amount to reach the predetermined value. A third example of the time T2 is a time when the time integration of the rotation speed started from the time T1 reaches a predetermined value. The time integration of the number of revolutions corresponds to the shaded area in FIGS. The higher the rotation speed during the fast idle mode M2, the shorter the time until the time integration of the rotation speed reaches the predetermined value. For example, in the fast idle mode M2, if the operator intentionally fully opens the throttle valve 8, the relatively high-power engine causes the rotation speed to increase as shown by the dashed line in FIG. You can

The predetermined rotation speed R2 is, for example, 3000 to 4000 rpm. In this case, a predetermined rotation speed range may be set in place of the predetermined rotation speed R2, and control may be performed with the target that the fast idle rotation speed falls within the predetermined rotation speed range.

In the first operation example, it is assumed that the operator returns the throttle valve 8 from the fast idle position 8b to the normal idle position 8a when the operation mode is the fast idle mode M2. In this case, at time T2, the rotation speed of the internal combustion engine 2 is lower than the clutch-in rotation speed R4. The control device 16 shifts the operation mode from the fast idle mode M2 to the normal idle mode M3 by detecting that the rotation speed of the internal combustion engine 2 when the fast idle mode M2 is released is lower than the clutch-in rotation speed R4. Let

In the normal idle mode M3, the control device 16 performs control such that a predetermined rotation speed R3 lower than the clutch-in rotation speed is set as the target rotation speed of the internal combustion engine 2. In this case, a predetermined rotation speed range may be set in place of the predetermined rotation speed R3, and control may be performed with the target that the normal idle rotation speed falls within the predetermined rotation speed range. The predetermined rotation speed R3 is a rotation speed that stably operates when the throttle valve 8 is at the idle position 8a, and is, for example, 1500 to 2500 rpm. The control may be control using a map that defines the relationship between the rotation speed and the ignition timing, or may be feedback control that detects the rotation speed and changes the ignition timing. The feedback control is preferably PI control.

The normal idle mode M3 is operated within a range having a boundary value of at least one of the rotational speed elements that changes according to the rotation of the internal combustion engine. The rotational speed element is, for example, the rotational speed itself, fluctuations in the rotational speed, and/or control variables that affect the rotational speed. When the rotational speed element exceeds one of the boundary values, the control device 16 releases the normal idle mode M3 and shifts the operating mode from the normal idle mode M3 to another operating mode. As an example, it is assumed that the rotation speed element is the rotation speed. One boundary value (upper limit value) is an upper limit rotation speed R3U that is higher than a predetermined rotation speed R3.

In the first operation example, it is assumed that the throttle valve 8 is moved from the normal idle position 8a to the acceleration position 8c when the operation mode is the normal idle mode M3. In this case, the rotation speed of the internal combustion engine 2 increases and becomes higher than the upper limit rotation speed R3U at time T4. The control device 16 shifts the operation mode from the normal idle mode M3 to the acceleration mode M4 by detecting that the rotation speed of the internal combustion engine 2 is higher than the upper limit rotation speed R3U.

In the acceleration mode M4, the control device 16 accelerates the internal combustion engine 2 using a map that defines the relationship between the rotation speed and the ignition timing.

In the first operation example, the control device 16 shifts the operation mode from the normal idle mode M3 to the acceleration mode M4 when the rotation speed of the internal combustion engine 2 exceeds the upper limit rotation speed R3U. The present invention is directed to the chainsaw 1 in which the internal combustion engine 2 having a relatively high output is mounted. As described above, when the operator fully opens the throttle valve 8 in the fast idle mode M2, the engine speed is It is configured to be higher than the clutch-in rotation speed R4. When the operating mode is shifted from the normal idle mode M3 to the acceleration mode M4 by the relatively high output internal combustion engine 2, the internal combustion engine 2 can respond sensitively to the operation of the operator. As a result, the operability of acceleration by the operator can be improved.

In the second operation example shown in FIG. 6, the control device 16 shifts the operation mode of the internal combustion engine 2 in the order of the start mode M1, the fast idle mode M2, and the acceleration mode M5. The starting mode M1 and the fast idle mode M2 are the same as in the first operation example.

In the second operation example, it is assumed that the throttle valve 8 is moved from the fast idle position 8b to the acceleration position 8c when or immediately after the operation mode becomes the fast idle mode M2. The engine working machine 1 is configured so that the rotation speed of the internal combustion engine 2 becomes higher than a predetermined clutch-in rotation speed R4 when the throttle valve 8 is set to the fully open position 8c in the fast idle mode M2. It is an engine working machine of. In this case, the rotational speed of the internal combustion engine 2 becomes higher than the clutch-in rotational speed R4 during the fast idle mode M2.

The control device 16 detects that the rotation speed of the internal combustion engine 2 when the time T2 is reached and the fast idle mode M2 is released is higher than the clutch-in rotation speed R4, so that the operation mode is changed from the fast idle mode M2. Transition to acceleration mode M5.

In the acceleration mode M5, the control device 16 accelerates the internal combustion engine 2 using the map that defines the relationship between the rotation speed and the ignition timing, and reaches the maximum speed R5.

In the first operation example and the second operation example, warm air can be promoted by moving the throttle valve 8 toward the fully open position during the fast idle mode M2 and/or canceling the fast idle mode M2. Can be shortened. In this way, the operator can promote warming up by a simple operation of fully opening the throttle valve 8. Further, in the first operation example, the operation mode can be rapidly shifted from the normal idle mode M3 to the acceleration mode M4, and in the second operation example, the operation mode can be quickly changed from the fast idle mode M2 to the acceleration mode M5. Can be transferred.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and various modifications can be made within the scope of the invention described in the claims, Needless to say, these are also included within the scope of the present invention.

Although the clutch has been described as the centrifugal clutch 4 in the above embodiment, the internal combustion engine 2 and the operating portion 3 are connected when the rotational speed of the internal combustion engine 2 is higher than a predetermined clutch-in rotational speed. Other clutches may be used as long as they are clutches that transmit the rotation of the internal combustion engine 2 to the operating portion 3.

Although the throttle valve 8 is provided in the carburetor 7 in the above embodiment, a fuel amount, air amount, and/or air-fuel mixture control device may be used instead of the carburetor 7.

1 Chainsaw (engine work machine)
2 Internal combustion engine 3 Chain with blade (operating part)
4 Centrifugal clutch (clutch)
7 Vaporizer (fuel amount, air amount, and/or mixture amount control device)
8 Throttle valve 8a Normal idle position 8b Fast idle position 8c Acceleration position 16 Control device 20 Microcomputer M2 Fast idle mode M3 Normal idle mode M4 Acceleration mode M5 Acceleration mode R2 Predetermined fast idle speed R3 Predetermined normal idle speed R3U Upper limit rotation Number (one boundary value)
R4 predetermined clutch-in speed R6 predetermined limit speed

Claims (8)

A portable engine working machine (1),
An internal combustion engine (2),
An operating part (3) driven by the internal combustion engine (2),
A clutch (4) arranged between the internal combustion engine (2) and the working part (3),
A control device (16) for detecting the rotation speed of the internal combustion engine (2) and controlling the rotation speed,
The clutch (4) connects the internal combustion engine (2) and the operating part (3) when the rotation speed of the internal combustion engine (2) is higher than a predetermined clutch-in rotation speed (R4). Then, the rotation of the internal combustion engine (2) is transmitted to the operating portion (3),
The internal combustion engine (2) has a fuel amount, air amount, and/or air-fuel ratio control device (7) including a throttle valve (8),
The control device (16) is configured to shift the operation mode of the internal combustion engine (2) to a fast idle mode (M2) after the internal combustion engine (2) is started, and the fast idle mode (M2). Then, if the throttle valve (8) is located at a predetermined fast idle position (8b) in which the throttle valve (8) is opened from the fully closed position or its vicinity (8a), the predetermined internal clutch-in speed ( The throttle valve (8) is configured to operate at a rotational speed lower than R4), and when the throttle valve (8) is in the fully open position (8c), operates at a rotational speed higher than the predetermined clutch-in rotational speed (R4). Is composed of
The control device (16) is configured to shift the operating mode of the internal combustion engine (2) to a normal idle mode (M3) after releasing the fast idle mode (M2). In M3), the internal combustion engine (2) is configured to operate normally at idle speed if the throttle valve (8) is at or near the fully closed position (8a), and the throttle valve (8) Is moved to the fully open position (8c) and the rotation speed of the internal combustion engine (8) exceeds one boundary value (R3U) of predetermined rotation speed elements, the control device (16) causes the normal idle mode ( An engine working machine configured to release M3) and shift the operation mode of the internal combustion engine (2) to an acceleration mode (M4). The engine working machine according to claim 1, wherein the control in the normal idle mode (M3) is a feedback control targeting the predetermined normal idle speed (R3). The engine working machine according to claim 2, wherein the feedback control in the normal idle mode (M3) is PI control. The engine work according to any one of claims 1 to 3, wherein the control device (16) performs feedback control targeting a predetermined fast idle speed (R2) in the fast idle mode (M2). Machine. The engine working machine according to claim 4, wherein the feedback control in the fast idle mode (M2) is PI control. The engine working machine according to any one of claims 1 to 5, wherein the control device (16) releases the fast idle mode (M2) after a predetermined period has elapsed from the start of the fast idle mode (M2). 6. The control device (16) releases the fast idle mode (M2) when the cumulative amount of rotations from the start of the fast idle mode (M2) reaches a predetermined value. Engine working machine described in. The control device (16) releases the fast idle mode (M2) when the time integration of the number of revolutions from the start of the fast idle mode reaches a predetermined value. The engine working machine according to item 1.

Images