JP2018173044A - Work machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a working machine capable of securing a time for firmly removing dust adhering to the periphery of a radiator by the wind of a cooling fan. SOLUTION: A radiator that dissipates heat from engine cooling water, a cooling fan that cools the radiator, and a cooling fan are set to have a forward flow state in which cooling air is supplied to the radiator and a reverse flow direction opposite to the normal flow state. A switching mechanism for switching to the state, an alternating mode in which the wind direction of the cooling fan is sequentially switched between the forward flow state and the backflow state, and the forward flow state is performed for a longer time than the backflow state, and the backflow state are continuously performed. A work machine equipped with a selection unit for selecting the backflow mode. [Selection diagram] Fig. 4

Description

  The present invention relates to a work machine.

  Conventionally, as a work machine, a radiator that dissipates engine cooling water, a cooling fan that cools the radiator, and the wind direction of the cooling fan, the normal flow state where the cooling air is supplied to the radiator and the normal flow state are opposite There is known a working machine including a switching mechanism for switching to a reverse flow state (see, for example, Patent Document 1).

  The working machine described in Patent Document 1 includes a rotation state switching mechanism that can switch between a forward rotation state in which the fan is rotated in the forward rotation direction for cooling and a reverse rotation state in which the fan is rotated in the reverse rotation direction for dust removal. ing. In the working machine described in Patent Document 1, the fan is switched to the forward rotation state in which the fan is driven forward, and then the fan is switched to the reverse rotation state in which the fan is driven in the reverse direction when the set time for forward rotation has elapsed. Then, when the reverse set time elapses after switching to the reverse rotation state, the normal rotation state is again switched. The operation of switching between the forward rotation state and the reverse rotation state is repeated, and the fan is driven to rotate reversely at set time intervals to blow away dust attached to the dust net.

JP 2017-57809 A

  In the working machine described in Patent Document 1, there is only a short time during which the airflow of the cooling fan is in the reverse flow state. For this reason, it is difficult to sufficiently remove dust adhering to the periphery of the radiator by the wind of the cooling fan.

  In view of the above situation, there is a demand for a working machine capable of ensuring time for firmly removing dust attached to the periphery of the radiator by the wind of the cooling fan.

The feature of the present invention is that
A radiator that dissipates engine cooling water;
A cooling fan for cooling the radiator;
A switching mechanism that switches the air direction of the cooling fan between a normal flow state in which cooling air is supplied to the radiator and a reverse flow state opposite to the normal flow state;
The air flow direction of the cooling fan is sequentially switched between the normal flow state and the reverse flow state, and the normal flow state is performed for a longer time than the reverse flow state, and the reverse flow mode in which the reverse flow state is continuously performed. And a selection unit for selecting.

  According to this characteristic configuration, in the alternate mode, the airflow direction of the cooling fan is sequentially switched between the normal flow state and the reverse flow state, and the normal flow state is performed for a longer time than the reverse flow state. Therefore, when the alternate mode is selected, the radiator can be effectively cooled, and dust attached to the periphery of the radiator can be removed to some extent by the wind of the cooling fan. On the other hand, when the reverse flow mode is selected, the cooling fan wind continuously flows in the reverse flow state. Thereby, if the reverse flow mode is selected by the selection unit, the wind direction of the cooling fan can be kept in the reverse flow state for a necessary time. As a result, it is possible to secure time for firmly removing dust adhering to the periphery of the radiator by the wind of the cooling fan.

Furthermore, in the present invention,
A detection unit for detecting the state of the aircraft,
A determination unit that determines whether the state of the aircraft satisfies a specific condition based on a detection result of the detection unit; and
Preferably, the selection unit automatically selects the backflow mode when the determination unit determines that the state of the aircraft satisfies the specific condition.

  According to this feature configuration, the reverse flow mode can be selected at an appropriate timing by setting a condition suitable for continuously performing the reverse flow state as the specific condition.

Furthermore, in the present invention,
A working device driven by engine driving force;
A working clutch that can be switched between an on-state for transmitting engine driving force to the working device and a cut-off state for shutting off engine driving force to the working device;
It is preferable that the specific condition is that the engine speed is equal to or lower than a predetermined speed and the work clutch is set to the engaged state.

  According to this characteristic configuration, it is possible to confirm that the operator has an intention to select the reverse flow mode when the worker switches the work clutch to the engaged state. That is, according to the present feature configuration, after confirming that the operator has an intention to select the reverse flow mode, the reverse flow mode is selected under a condition where the engine cooling water whose engine speed is equal to or lower than a predetermined speed is relatively low. Can be selected at an appropriate timing.

Furthermore, in the present invention,
In the forward flow state, the selection unit preferably selects the reverse flow mode as soon as the work clutch is switched from the disengaged state to the engaged state when the engine speed is equal to or less than the predetermined speed.

  According to this characteristic configuration, it is possible to quickly switch from the normal flow state to the reverse flow state in accordance with the timing at which the work clutch is switched to the engaged state.

Furthermore, in the present invention,
When the working clutch is switched from the disengaged state to the engaged state and the working clutch is switched to the engaged state when the engine speed is equal to or less than the predetermined rotational speed in the positive flow state, It is preferable to select the reverse flow mode when a certain time has passed since the start of the operation.

  When the operator accidentally switches the work clutch to the on state (for example, when the body touches the operating tool that switches the work clutch between the on state and the off state), the reverse flow mode is immediately activated. May be inconvenient. On the other hand, if a certain time elapses from when the work clutch is switched to the engaged state, it can be inferred that the operator is willing to select the reverse flow mode with the elapse of the certain time. That is, according to this feature configuration, it is possible to avoid a situation in which the reverse flow mode is selected against the will of the operator.

Furthermore, in the present invention,
The alternate mode is selected when the engine speed is higher than the constant speed and the working clutch is in the engaged state,
In the alternate mode, the selection unit selects the reverse flow mode when switching to the next reverse flow state in the alternate mode if the engine rotational speed drops below the predetermined rotational speed and the forward flow state. And if it is the said backflow state, it is suitable to make it transfer to the said backflow mode by continuing the said backflow state in the said alternating mode.

  According to this feature configuration, the control configuration for performing the backflow state can be shared between the alternating mode and the backflow mode, and the control configuration can be simplified.

Furthermore, in the present invention,
In the reverse flow mode, the selection unit shifts to the normal flow mode in which the normal flow state is continuously performed when the specific condition is not satisfied by switching the working clutch to the disengaged state. When the engine speed exceeds the fixed speed and the specific condition is not satisfied, it is preferable to shift to the alternate mode.

  According to this feature, in the reverse flow mode, when the work clutch is switched to the disengaged state, the operator is allowed to interrupt the reverse flow mode. In this case, it is appropriate to shift to the forward flow mode so that the reverse flow state is not performed. On the other hand, in the reverse flow mode, when the specific condition is not satisfied because the engine speed exceeds a certain speed, the operator does not indicate the intention to interrupt the reverse flow mode. It is appropriate to shift to the alternate mode. That is, according to this feature configuration, it is possible to appropriately select whether to shift to the forward flow mode or to the alternate mode depending on the mode in which the specific condition is no longer satisfied during the reverse flow mode. .

Furthermore, in the present invention,
The working device is configured to normally operate in a rotational speed region of a specific rotational speed that is higher than a constant rotational speed.
It is preferable that an alarm device for alarming is provided when the working clutch is in the engaged state and the engine speed is lower than the specific speed.

  According to this feature configuration, when the reverse flow mode is selected, that is, when the engine speed is equal to or lower than the predetermined speed and the work clutch is in the engaged state, an alarm is issued by the alarm device. . Thereby, it is possible to make the operator clearly recognize that the reverse flow mode is selected by using the alarm device for the action device.

Furthermore, in the present invention,
An operation unit capable of outputting an alternating command for selecting the alternating mode and a reverse flow command for selecting the reverse flow mode by human operation is provided,
It is preferable that the selection unit selects the alternate mode and the backflow mode based on a command output by the operation unit.

  According to this feature configuration, the operator can select the alternating mode and the reverse flow mode flexibly by operating the operation unit.

Furthermore, in the present invention,
When the selection unit receives the backflow command in the normal flow state, the selection unit preferably selects the backflow mode immediately.

  According to this characteristic configuration, it is possible to switch from the normal flow state to the reverse flow state at an early stage in accordance with the timing when the operator operates the operation unit.

Furthermore, in the present invention,
When the selection unit receives the backflow command in the normal flow state, the selection unit preferably selects the backflow mode when a predetermined time has elapsed since the reception of the backflow command.

  According to this feature configuration, when the operator has unintentionally operated the operation unit (for example, when the operator has made an erroneous operation), it may be inconvenient if the reverse flow mode is immediately selected. On the other hand, if a certain period of time has elapsed since the reception of the backflow command, it can be inferred that the operator is willing to select the backflow mode with the lapse of the certain time. That is, according to this feature configuration, it is possible to avoid a situation in which the reverse flow mode is selected against the will of the operator.

Furthermore, in the present invention,
When the selection unit receives the alternate command during the reverse flow mode, it is preferable that the selection unit shifts to the alternate mode in the forward flow state.

  According to this characteristic configuration, the radiator can be cooled by the cooling air of the cooling fan immediately after the transition from the reverse flow mode to the alternate mode.

Furthermore, in the present invention,
When the selection unit receives the alternating command during the reverse flow mode, it is preferable that the selection unit shifts to the alternating mode in the reverse flow state.

  According to this feature configuration, since the airflow direction (backflow state) of the cooling fan does not change immediately after the transition from the backflow mode to the alternate mode, the transition from the backflow mode to the alternate mode can be performed smoothly.

It is a right view which shows a normal type combine. It is a figure which shows a control block. It is a table | surface which shows the state of the body in each of normal flow mode, alternating mode, and reverse flow mode, and the wind direction of a cooling fan. It is a figure which shows the relationship between an engine speed, the state of a threshing clutch, the state of an alarm device, and the wind direction of a cooling fan. It is a table | surface which shows the aspect switched from a normal flow mode or an alternating mode to a reverse flow mode. It is a table | surface which shows the aspect switched from reverse flow mode to forward flow mode or an alternating mode. In another embodiment, it is a figure which shows the boundary of the reverse flow mode and alternating mode at the time of the transition from reverse flow mode to alternating mode.

  EMBODIMENT OF THE INVENTION The form for implementing this invention is demonstrated based on drawing. In the following description, the direction of arrow F shown in FIG. 1 is “front side”, the direction of arrow B is “back side”, the left side in the direction of arrow F is “left side”, and the direction of arrow F The right side of the aircraft is the “airframe right side”.

[Overall configuration of ordinary combine]
FIG. 1 shows an ordinary combine (corresponding to a “work machine” according to the present invention). The combine includes a body frame 1 and a traveling device 2. The traveling device 2 includes a pair of left and right front wheels 2F that can be driven, and a pair of left and right rear wheels 2R that can be steered. In front of the machine body, a cutting unit 3 for cutting the planted cereals is provided. A driving unit 4 on which the driver gets on and a cabin 5 that covers the driving unit 4 are provided at the front of the aircraft.

  A grain storage tank 6 for storing grains is provided behind the cabin 5. Next to the grain storage tank 6, a threshing device 7 (corresponding to the “working device” according to the present invention) for threshing the harvested cereal meal is provided. A feeder 8 is provided across the harvesting unit 3 and the threshing device 7 to convey the harvested cereal meal toward the threshing device 7. A grain discharging device 9 for discharging the grains in the grain storage tank 6 is provided.

  An engine E is provided on the front right side of the aircraft. A radiator 10 that dissipates engine cooling water and a cooling fan 11 that cools the radiator 10 are provided on the right side of the rear part of the machine body. A dust-proof net 12 is attached to a portion of the right side of the airframe that faces the radiator 10 so as to cover the radiator 10 from the lateral outer side (right side) of the airframe.

  A threshing clutch (corresponding to the “working clutch” according to the present invention, not shown) is provided in the power transmission path for transmitting the driving force from the engine E to the threshing device 7. The threshing clutch can be switched between an on state in which the engine driving force is transmitted to the threshing device 7 and a cut state in which the engine driving force to the threshing device 7 is cut off.

  The operation unit 4 is provided with a clutch lever (not shown) for switching the threshing clutch between the on state and the off state, an accelerator lever (not shown) and an accelerator pedal (not shown) for operating the engine speed. ing.

[Control block]

  As shown in FIG. 2, a switching mechanism 13 is provided that switches the wind direction of the cooling fan 11 between a normal flow state in which cooling air is supplied to the radiator 10 and a reverse flow state that is opposite to the normal flow state. In the normal flow state, the air outside the airframe flows as cooling air toward the inside of the airframe through the dust net 12, and in the reverse flow state, the air inside the airframe flows toward the outside of the airframe via the dust net 12.

The switching mechanism 13 is, for example, an actuator that switches the rotation direction of the cooling fan 11 between a direction corresponding to the forward flow state (forward rotation direction) and a direction corresponding to the reverse flow state (reverse rotation direction), and the blades of the cooling fan 11. This is an actuator that switches the direction between a direction corresponding to a normal flow state and a direction corresponding to a reverse flow state. These actuators may be electric motors, or may be hydraulic motors, electric cylinders, and hydraulic cylinders.

  An engine speed sensor 15 (corresponding to the “detection unit” according to the present invention) and a clutch sensor 16 (corresponding to the “detection unit” according to the present invention) are connected to the input side of the control unit 14. The engine speed sensor 15 detects the engine speed. The clutch sensor 16 detects the position of the clutch lever (an input position where the threshing clutch is in an on state, a cut position where the threshing clutch is in a disengaged state). A switching mechanism 13 and an alarm device 17 are connected to the output side of the control unit 14. The alarm device 17 is, for example, a speaker or a display, and issues an alarm based on an alarm command from the control unit 14 (alarm unit 20).

  The control unit 14 includes a determination unit 18, a selection unit 19, and an alarm unit 20. Based on the detection results of the engine speed sensor 15 and the clutch sensor 16, the determination unit 18 determines whether or not the state of the aircraft satisfies a specific condition (details will be described later). The “state of the aircraft” in the present embodiment refers to the engine speed and the state of the threshing clutch (whether it is in the on state or in the off state).

  The selection unit 19 selects a normal flow mode, an alternating mode, and a reverse flow mode. When the determination unit 18 determines that the state of the aircraft satisfies the specific condition, the selection unit 19 automatically selects the backflow mode.

  As shown in FIG. 3, the positive flow mode is a mode in which the positive flow state is continuously performed. The normal flow mode is selected when the threshing clutch is in a disengaged state. That is, if the threshing clutch is in the disengaged state, the normal flow mode is selected regardless of the engine speed.

  The alternating mode is a mode in which the airflow direction of the cooling fan 11 is sequentially switched between a normal flow state and a reverse flow state, and the normal flow state is performed for a longer time than the reverse flow state. The alternate mode is selected when the engine speed is higher than the constant speed Nc and the threshing clutch is in the engaged state. In this embodiment, the time during which the normal flow state is performed is defined as the normal flow state time t1, and the time during which the reverse flow state is performed is defined as the reverse flow state time t2 (see FIG. 4).

  The reverse flow mode is a mode in which the reverse flow state is continuously performed. The reverse flow mode is selected when the engine speed is equal to or lower than a constant speed Nc and the threshing clutch is in the engaged state. That is, in the “specific condition” in the present embodiment, the engine speed is equal to or less than a certain speed Nc, and the threshing clutch is set to the engaged state. Here, “continuation” means that the time is longer than the time during which the backflow state in the alternate mode is performed (backflow state time t2 in FIG. 4).

  By the way, the threshing device 7 normally operates (that is, performs a normal threshing process) in a rotation speed region equal to or higher than a specific rotation speed (specific rotation speed Nh in FIG. 4) higher than the constant rotation speed Nc. ) Is configured as follows. The warning unit 20 instructs the warning device 17 to issue a warning (warning command) when the threshing clutch is in the engaged state and the engine speed is lower than the specific speed Nh.

[Control contents]
As shown in FIG. 4, the forward flow mode is selected before the start of work after the engine is started (the threshing clutch is in a disengaged state). In A <b> 1-1 in FIG. 4, when the threshing clutch is switched from the disengaged state to the engaged state in a state where the engine speed is equal to or less than the constant engine speed Nc, the determination unit 18 determines that the state of the machine body satisfies the specific condition Is determined. Then, the selection unit 19 automatically selects the backflow mode. Specifically, the selection unit 19 selects the reverse flow mode when a certain time tc has elapsed from when the threshing clutch is switched to the engaged state. That is, as shown in the column A1-1 in FIG. 5, in the normal flow mode (normal flow state), the selection unit 19 allows the threshing clutch to be released from the disengaged state when the engine speed is equal to or less than a predetermined speed Nc. When switched to the on state, the reverse flow mode is selected when a certain time tc has elapsed from when the threshing clutch is switched to the on state. Here, the fixed time tc is set to be longer than the backflow state time t2. Although a detailed description is omitted, the backflow mode is selected in the same manner as A1-1 in A1-2 in FIG. 4 (see the column A1-2 in FIG. 5).

  In B1 in FIG. 4, when the threshing clutch is switched from the on state to the off state in a state where the engine speed is equal to or less than the constant speed Nc, the determination unit 18 determines that the state of the fuselage does not satisfy the specific condition. To do. In B <b> 1 in FIG. 4, the specific condition is not satisfied by switching the threshing clutch to the disengaged state during the reverse flow mode. In this case, the selection unit 19 selects the normal flow mode. Specifically, the selection unit 19 selects the forward flow mode when the reverse flow state time t2 has elapsed from when the threshing clutch is switched from the on state to the off state. That is, as shown in the column B1 in FIG. 6, the selection unit 19 shifts to the normal flow mode when the specific condition is not satisfied by switching the threshing clutch to the disengaged state during the reverse flow mode.

  In B2-1 in FIG. 4, when the threshing clutch is in the engaged state and the engine speed exceeds a certain speed Nc, the determination unit 18 determines that the state of the aircraft does not satisfy the specific condition. In B2-1 in FIG. 4, the specific condition is not satisfied because the engine speed exceeds the fixed speed Nc during the reverse flow mode. In this case, the selection unit 19 selects the alternate mode. Specifically, the selection unit 19 selects the alternating mode when the reverse flow state time t2 has elapsed from when the engine speed exceeds a certain speed Nc. That is, as shown in the column of B2-1 in FIG. 6, the selection unit 19 performs the alternating mode when the specific condition is not satisfied because the engine speed exceeds the fixed speed Nc during the reverse flow mode. To migrate. Although a detailed description is omitted, the alternating mode is selected in the same manner as B2-1 in B2-2 in FIG. 4 (see the column B2-2 in FIG. 6).

  In A <b> 2 in FIG. 4, when the threshing clutch is in the engaged state and the engine speed is reduced to a predetermined speed Nc or less, the determination unit 18 determines that the state of the machine body satisfies the specific condition. Then, the selection unit 19 automatically selects the backflow mode. Specifically, in A2 in FIG. 4, since the forward flow state is in the alternating mode, the selection unit 19 selects the reverse flow mode when switching to the next reverse flow state in the alternating mode. That is, as shown in the column A2 in FIG. 5, when the engine speed is decreased to a predetermined speed Nc or less during the alternate mode, the selection unit 19 determines that the next backflow in the alternate mode is in the normal flow state. Select reverse flow mode when switching to state.

  In A3 in FIG. 4, when the threshing clutch is in the engaged state and the engine speed is reduced to a predetermined speed Nc or less, the determination unit 18 determines that the state of the machine body satisfies the specific condition. Then, the selection unit 19 automatically selects the backflow mode. Specifically, in A3 in FIG. 4, since the backflow state is in the alternating mode, the selection unit 19 continues the backflow state in the alternating mode and shifts to the backflow mode. That is, as shown in the column A3 in FIG. 5, the selection unit 19 continues the backflow state in the alternating mode if the engine speed decreases to a predetermined speed Nc or less during the alternating mode if the backflow state occurs. By doing so, the mode is changed to the reverse flow mode.

[Another embodiment]
(1) In the above embodiment, a forward flow mode, an alternating mode, and a reverse flow mode are provided. However, instead of this, the forward flow mode may not be provided. In this case, the positive flow mode is replaced with the alternate mode. Alternatively, another mode may be provided in addition to the normal flow mode, the alternating mode, and the reverse flow mode.

(2) In the above-described embodiment, when the engine speed is equal to or lower than the constant speed Nc in the normal flow state, the selection unit 19 is in the on state when the threshing clutch is switched from the off state to the on state. When a certain time tc has elapsed since the time of switching to, the reverse flow mode is selected. However, instead of this, the selection unit 19 selects the reverse flow mode as soon as the threshing clutch is switched from the disengaged state to the on state when the engine speed is equal to or lower than the constant engine speed Nc in the normal flow state. It may be configured.

(3) In the above embodiment, the threshing clutch is provided as the “working clutch” according to the present invention. However, instead of this, or together with this, as the “work clutch” according to the present invention, an on state in which the engine driving force is transmitted to the cutting unit 3 and a cut off state in which the engine driving force to the cutting unit 3 is cut off. A mowing clutch (not shown) that can be switched to is also provided.

(4) In the above embodiment, when the engine speed is reduced to the constant rotational speed Nc or less during the alternate mode, the selection unit 19 performs the reverse flow when switching to the next reverse flow state in the alternate mode if the forward flow state. Select a mode. However, instead of this, in the alternate mode, the selection unit 19 reduces the engine speed to a certain rotational speed Nc or less when the engine rotational speed is decreased to the constant rotational speed Nc or less in a positive flow state. Sometimes it may be configured to select the backflow mode.

(5) In the above-described embodiment, when the engine speed is reduced to the constant rotation speed Nc or less during the alternate mode, the selection unit 19 continues the reverse flow state in the alternate mode if the reverse flow state occurs. The mode is changed (see A3 in FIG. 4). That is, when the engine speed is reduced to a predetermined speed Nc or less during the alternating mode, the selection unit 19 ends the backflow state in the alternating mode (when the backflow state time t2 has elapsed). Then, shift to the reverse flow mode. However, instead of this, when the engine speed is reduced to a constant rotational speed Nc or less in the alternate mode, the selection unit 19 is in a reverse flow state, and when the engine rotational speed is reduced to a constant rotational speed Nc or less. It may be configured to shift to the reverse flow mode during the reverse flow state time t2 in the alternating mode.

(6) In the above embodiment, the boundary between the backflow mode and the alternating mode at B2-1 and B2-2 in FIG. 4 can be set as shown in FIG. 7, for example. That is, in FIG. 4, the reverse flow state from the time when the engine rotation speed exceeds the fixed rotation speed Nc to the time when the reverse flow state time t2 has elapsed is included in the reverse flow mode, whereas in FIG. The backflow state from when the rotational speed exceeds the constant rotational speed Nc to when the backflow state time t2 has elapsed is included in the alternate mode.

(7) In the above embodiment, the selection unit 19 automatically selects the reverse flow mode when the determination unit 18 determines that the state of the aircraft satisfies the specific condition. However, instead of this, or together with this, an operation unit (not shown) capable of outputting an alternating command for selecting the alternating mode and a reverse flow command for selecting the reverse flow mode by human operation is provided. May be configured to select an alternating mode and a backflow mode based on a command output by the operation unit.

  In this case, the selection unit 19 may be configured to immediately select the backflow mode when receiving a backflow command in the normal flow state. Alternatively, the selection unit 19 may be configured to select the backflow mode when a backflow command is received in a normal flow state, when a predetermined time has elapsed since the backflow command was received.

  Moreover, the selection part 19 may make it transfer to an alternating mode in a normal flow state, when an alternating command is received during a reverse flow mode. Alternatively, when the selection unit 19 receives an alternating command during the reverse flow mode, the selection unit 19 may shift to the alternating mode in the reverse flow state.

  The present invention can be used not only for a general combine but also for a self-removing combine and a corn harvester.

7 Threshing device (working device)
DESCRIPTION OF SYMBOLS 10 Radiator 11 Cooling fan 13 Switching mechanism 15 Engine speed sensor (detection part)
16 Clutch sensor (detector)
17 Alarm device 18 Judgment part 19 Selection part Nc Constant rotation speed tc Constant time

Claims (13)

A radiator that dissipates engine cooling water;
A cooling fan for cooling the radiator;
A switching mechanism that switches the air direction of the cooling fan between a normal flow state in which cooling air is supplied to the radiator and a reverse flow state opposite to the normal flow state;
The air flow direction of the cooling fan is sequentially switched between the normal flow state and the reverse flow state, and the normal flow state is performed for a longer time than the reverse flow state, and the reverse flow mode in which the reverse flow state is continuously performed. And a work unit provided with a selection unit for selecting the machine. A detection unit for detecting the state of the aircraft,
A determination unit that determines whether the state of the aircraft satisfies a specific condition based on a detection result of the detection unit; and
The work machine according to claim 1, wherein the selection unit automatically selects the backflow mode when the determination unit determines that the state of the machine body satisfies the specific condition. A working device driven by engine driving force;
A working clutch that can be switched between an on-state for transmitting engine driving force to the working device and a cut-off state for shutting off engine driving force to the working device;
The work machine according to claim 2, wherein the specific condition is that an engine speed is equal to or less than a predetermined speed and the work clutch is set to the engaged state.   The said selection part selects the said reverse flow mode as soon as the said operation clutch switches from the said disengagement state to the said engagement state in the said normal flow state, when an engine speed is below the said fixed speed. The working machine described.   When the working clutch is switched from the disengaged state to the engaged state and the working clutch is switched to the engaged state when the engine speed is equal to or less than the predetermined rotational speed in the positive flow state, The work machine according to claim 3, wherein the reverse flow mode is selected when a predetermined time has elapsed since the start of the operation. The alternate mode is selected when the engine speed is higher than the constant speed and the working clutch is in the engaged state,
In the alternate mode, the selection unit selects the reverse flow mode when switching to the next reverse flow state in the alternate mode if the engine rotational speed drops below the predetermined rotational speed and the forward flow state. And if it is the said backflow state, the working machine as described in any one of Claim 3 to 5 which makes it transfer to the said backflow mode by continuing the said backflow state in the said alternate mode.   In the reverse flow mode, the selection unit shifts to the normal flow mode in which the normal flow state is continuously performed when the specific condition is not satisfied by switching the working clutch to the disengaged state. The work machine according to any one of claims 3 to 6, wherein when the specific condition is no longer satisfied because the engine speed exceeds the fixed speed, the mode is shifted to the alternate mode. The working device is configured to normally operate in a rotational speed region of a specific rotational speed that is higher than a constant rotational speed.
The work machine according to any one of claims 3 to 7, further comprising a warning device that issues a warning when the work clutch is in the engaged state and the engine speed is lower than the specific speed. . An operation unit capable of outputting an alternating command for selecting the alternating mode and a reverse flow command for selecting the reverse flow mode by human operation is provided,
The work machine according to claim 1, wherein the selection unit selects the alternate mode and the backflow mode based on a command output by the operation unit.   The work machine according to claim 9, wherein the selection unit selects the backflow mode immediately upon receiving the backflow command in the normal flow state.   The work implement according to claim 9, wherein when the selection unit receives the backflow command in the normal flow state, the selection unit selects the backflow mode when a predetermined time has elapsed since the reception of the backflow command.   The work machine according to any one of claims 9 to 11, wherein the selection unit shifts to the alternate mode in the forward flow state when the alternate command is received during the reverse flow mode.   The work machine according to any one of claims 9 to 11, wherein when the selection unit receives the alternate command during the reverse flow mode, the selection unit shifts to the alternating mode in the reverse flow state.

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