JP2024059231A - Work machine and method for controlling a work machine - Google Patents

Abstract

[Problem] In a work machine, fuel efficiency is improved by controlling the engine with an appropriate output according to the load on the work machine. [Solution] The work machine includes a vehicle body, an engine, a travelling device, a work machine, a sensor, and a controller. The sensor detects status data indicating the operating status of the travelling device and the work machine. The controller acquires the status data. The controller determines the work situation of the work machine based on the operating status of the travelling device and the work machine. When the controller determines that the work situation is a specified work other than excavation, it controls the engine output in a first control mode. When the controller determines that the work situation is excavation, it controls the engine output in a second control mode. In the second control mode, the controller reduces the upper limit of the engine output more than in the first control mode. [Selected Figure] Figure 5

Description

The present disclosure relates to a work machine and a method for controlling a work machine.

Some work machines, such as construction machines, detect the current work situation and automatically control the engine output. For example, in the work machine of Patent Document 1, the controller determines whether the work machine is digging or climbing. When the work machine is digging or climbing, the engine is operated at high output, and when the work machine is performing other tasks, the engine is operated at low output.

International Publication WO2005/024208

In the above-mentioned work machine, engine output is increased during work situations where the load on the work machine is high, such as excavation or climbing. On the other hand, engine output is limited during work situations where the load on the work machine is low.

In recent years, work machines with high-power engines have appeared in order to improve fuel efficiency. High-power engines generate the same output as conventional engines at a low engine speed. This can improve the fuel efficiency of the work machine. However, in work machines with high-power engines, the engine is operated at an output that is excessively high compared to the load on the work machine, which can actually worsen fuel efficiency. The purpose of this disclosure is to improve fuel efficiency in work machines by controlling the engine at an appropriate output according to the load on the work machine.

A work machine according to one aspect of the present disclosure includes a vehicle body, an engine, a travel device, a work implement, a sensor, and a controller. The engine is mounted on the vehicle body. The travel device is mounted on the vehicle body. The travel device is driven by driving force from the engine to cause the vehicle body to travel. The work implement is operably supported on the vehicle body. The work implement operates by driving force from the engine. The sensor detects status data indicating the operating status of the travel device and the work implement. The controller controls the engine, the travel device, and the work implement.

The controller acquires the status data. The controller determines the work situation of the work machine based on the operating status of the travelling device and the work implement. When the controller determines that the work situation is a specified work other than excavation, the controller controls the engine output in a first control mode. When the controller determines that the work situation is excavation, the controller controls the engine output in a second control mode. In the second control mode, the controller reduces the upper limit of the engine output more than in the first control mode.

A method according to another aspect of the present disclosure is a method for controlling a work machine. The work machine includes a vehicle body, an engine, a travel device, and a work implement. The engine is mounted on the vehicle body. The travel device is mounted on the vehicle body. The travel device is driven by a driving force from the engine to travel the vehicle body. The work implement is operably supported on the vehicle body. The work implement operates by the driving force from the engine. The method includes acquiring status data indicating an operating state of the travel device and the work implement, determining a work phase of the work machine based on the operating state of the travel device and the work implement, controlling the output of the engine in a first control mode when it is determined that the work phase is a predetermined work other than excavation, controlling the output of the engine in a second control mode when it is determined that the work phase is excavation, and reducing the upper limit of the engine output in the second control mode compared to the first control mode.

According to the present disclosure, when the work situation is determined to be excavation, the engine output is controlled in the second control mode. In the second control mode, the upper limit of the engine output is lower than in the first control mode. As a result, during excavation work, the engine is controlled at an appropriate output according to the load on the work machine, thereby improving fuel efficiency.

FIG. 1 is a side view of a work machine according to an embodiment. FIG. 2 is a block diagram showing the configuration of a work machine. FIG. 4 is a block diagram showing a process for determining a target output torque of the engine. FIG. 4 is a diagram showing torque distribution between a required torque of a work implement and a required torque of a transmission. 4 is a flowchart showing a process for limiting engine output. FIG. 4 is a diagram showing a first torque upper limit and a second torque upper limit of a target output torque of an engine. 5 is a timing chart showing an upper limit of engine output that is changed depending on a work situation.

An embodiment of the present disclosure will now be described with reference to the drawings. FIG. 1 is a side view of a work machine 1 according to an embodiment. In this embodiment, the work machine 1 is a wheel loader. As shown in FIG. 1, the work machine 1 includes a vehicle body 2 and a work implement 3.

The vehicle body 2 includes a front vehicle body 2a and a rear vehicle body 2b. The rear vehicle body 2b is connected to the front vehicle body 2a so that it can turn left and right. A hydraulic cylinder 15 is connected to the front vehicle body 2a and the rear vehicle body 2b. The hydraulic cylinder 15 extends and retracts, causing the front vehicle body 2a to turn left and right relative to the rear vehicle body 2b.

The working machine 3 is used for operations such as excavation, transportation, and soil removal. The working machine 3 is attached to the front vehicle body 2a so as to be operable. The working machine 3 includes a boom 11, a bucket 12, and hydraulic cylinders 13 and 14. The boom 11 and the bucket 12 are operated by the extension and retraction of the hydraulic cylinders 13 and 14.

Figure 2 is a block diagram showing the configuration of the work machine 1. As shown in Figure 2, the work machine 1 includes an engine 21, a first drive system 22, and a second drive system 23. The engine 21 is, for example, a diesel engine. The engine 21 is provided with a fuel injection device 30. The fuel injection device 30 controls the output of the engine 21 by adjusting the amount of fuel injected into the cylinders of the engine 21.

The first drive system 22 includes a transmission 24 and a traveling device 25. The transmission 24 is connected to the engine 21. The transmission 24 transmits driving force from the engine 21 to the traveling device 25. For example, the transmission 24 is a hydraulic mechanical transmission (HMT). The HMT includes a planetary gear mechanism and a hydraulic pump/motor. The HMT can change the gear ratio steplessly by controlling the capacity of the hydraulic pump/motor.

However, the transmission 24 may be another type of transmission, such as an electric mechanical transmission (EMT) or a hydrostatic transmission (HST). Alternatively, the transmission 24 may be a transmission that includes a torque converter and multiple speed change gears.

The running device 25 is mounted on the vehicle body 2 and is driven by driving force from the engine 21 to cause the vehicle body 2 to run. The running device 25 includes axles 26, 27, front wheels 28, and rear wheels 29. The axles 26, 27 are connected to the transmission 24. The front wheels 28 are provided on the front vehicle body 2a. The rear wheels 29 are provided on the rear vehicle body 2b. The axle 26 transmits the driving force from the transmission 24 to the front wheels 28. The axle 27 transmits the driving force from the transmission 24 to the rear wheels 29.

The second drive system 23 includes a PTO (Power Take Off) 31, a hydraulic pump 32, and a control valve 33. The PTO 31 distributes the driving force of the engine 21 to the transmission 24 and the hydraulic pump 32. Note that only one hydraulic pump 32 is shown in FIG. 2. However, two or more hydraulic pumps may be connected to the engine 21 via the PTO 31.

The hydraulic pump 32 is connected to the engine 21 via the PTO 31. The hydraulic pump 32 is driven by the engine 21 and discharges hydraulic oil. The hydraulic oil discharged from the hydraulic pump 32 is supplied to the hydraulic cylinders 13-15 described above. Note that in FIG. 2, only the hydraulic cylinder 13 is shown, and the other hydraulic cylinders 14 and 15 are omitted.

The control valve 33 controls the flow rate of hydraulic oil supplied from the hydraulic pump 32 to the hydraulic cylinders 13-15. The control valve 33 is, for example, an electromagnetic proportional control valve, and is controlled in response to an input electrical signal. Alternatively, the control valve 33 may be a pressure proportional control valve, and is controlled in response to an input pilot pressure.

The work machine 1 includes an engine sensor 34 and a vehicle speed sensor 35. The engine sensor 34 detects the engine rotation speed. The vehicle speed sensor 35 detects the output rotation speed of the travel device 25. The output rotation speed of the travel device 25 corresponds to the vehicle speed of the work machine 1. The output rotation speed of the travel device 25 is, for example, the rotation speed of the output shaft of the transmission 24. However, the output rotation speed may also be the rotation speed of another rotating element located within the transmission 24 or downstream of the transmission 24.

The work machine 1 includes a pump pressure sensor 36 and a cylinder pressure sensor 37. The pump pressure sensor 36 detects the discharge pressure of the hydraulic pump 32. The cylinder pressure sensor 37 detects the boom bottom pressure of the hydraulic cylinder 13. The boom bottom pressure is the hydraulic pressure supplied to the hydraulic cylinder 13 when the hydraulic cylinder 13 is extended.

The work machine 1 includes a work implement attitude sensor 38 and a vehicle body attitude sensor 39. The work implement attitude sensor 38 detects the attitude of the work implement 3. The attitude of the work implement 3 includes, for example, the boom angle. The boom angle is the angle of the boom 11 with respect to the horizontal direction. The work implement attitude sensor 38 is, for example, an angle sensor attached to the boom 11. Alternatively, the work implement attitude sensor 38 may be a stroke sensor that detects the stroke amount of the hydraulic cylinder 13. In that case, the boom angle may be calculated from the stroke amount of the hydraulic cylinder 13 detected by the stroke sensor.

The vehicle body attitude sensor 39 detects the attitude of the vehicle body 2. The attitude of the vehicle body 2 includes, for example, the pitch angle and roll angle of the vehicle body 2. The vehicle body attitude sensor 39 is, for example, an IMU (Inertial Measurement Unit). Alternatively, the vehicle body attitude sensor 39 may be a sensor other than an IMU.

The work machine 1 includes a controller 41. The controller 41 includes a processor such as a CPU (central processing unit) and a storage device such as a RAM and a ROM. The controller 41 may include an auxiliary storage device such as a hard disk or an SSD (Solid State Drive). The controller 41 stores programs and data for controlling the work machine 1. The controller 41 executes processing for controlling the work machine 1 in accordance with the stored programs and data.

The controller 41 receives a signal indicating the engine rotation speed from the engine sensor 34. The controller 41 receives a signal indicating the output rotation speed from the vehicle speed sensor 35. The controller 41 receives a signal indicating the discharge pressure of the hydraulic pump 32 from the pump pressure sensor 36. The controller 41 receives a signal indicating the boom bottom pressure from the cylinder pressure sensor 37. The controller 41 receives a signal indicating the attitude of the work implement 3 from the work implement attitude sensor 38. The controller 41 receives a signal indicating the attitude of the vehicle body 2 from the vehicle body attitude sensor 39.

The controller 41 controls the output of the engine 21 by sending a command signal to the engine 21. The controller 41 switches between the forward gear and the reverse gear of the transmission 24 by sending a command signal to the transmission 24. The controller 41 controls the gear ratio of the transmission 24 by sending a command signal to the transmission 24. The controller 41 controls the work machine 3 by sending a command signal to the hydraulic pump 32 and the control valve 33.

The work machine 1 includes an FR operating member 42, an accelerator operating member 43, a work machine operating member 44, and an input device 45. The FR operating member 42 can be operated by an operator to switch the work machine 1 between forward and reverse. The FR operating member 42 can be operated from a neutral position to a forward position and a reverse position. The FR operating member 42 is, for example, a lever. However, the FR operating member 42 may also be another member such as a switch or a pedal.

The accelerator operating member 43 can be operated by an operator to control the vehicle speed of the work machine 1. The accelerator operating member 43 is, for example, a pedal. However, the accelerator operating member 43 may be another member such as a lever or a switch. The work machine operating member 44 can be operated by an operator to control the work machine 3. The work machine operating member 44 is, for example, a lever. However, the work machine operating member 44 may be another member such as a switch or a pedal.

The input device 45 can be operated by an operator to set the control of the work machine 1. For example, the input device 45 sets the work machine 1 in response to the operation of the operator. The input device 45 includes, for example, a touch panel. However, the input device 45 may also include other components such as a mechanical switch.

The controller 41 receives a signal indicating the operating position of the FR operating member 42 from the FR operating member 42. The controller 41 switches between the forward gear and the reverse gear of the transmission 24 in response to the signal from the FR operating member 42. The controller 41 receives a signal indicating the accelerator operation amount from the accelerator operating member 43. The accelerator operation amount is the operation amount of the accelerator operating member 43. The controller 41 receives a signal indicating the work machine operation amount from the work machine operating member 44. The work machine operation amount is the operation amount of the work machine operating member 44. The controller 41 receives a signal indicating the setting of the work machine 1 from the input device 45.

Next, the process for controlling the engine 21 executed by the controller 41 will be described. FIG. 3 is a block diagram showing the process for controlling the engine 21. As shown in FIG. 3, in step S101, the controller 41 determines the required torque of the transmission 24 (hereinafter referred to as T/M required torque). The T/M required torque is the output torque of the engine 21 required to run the work machine 1 by the traveling device 25. The T/M required torque increases or decreases according to the accelerator operation amount. The controller 41 determines the T/M required torque mainly from the accelerator operation amount and the output rotation speed.

For example, the controller 41 stores first required torque data D1. The first required torque data D1 specifies the relationship of the target traction force (Ft) of the work machine 1 to the output rotation speed (V) and the accelerator operation amount (A1). The controller 41 determines the target traction force (Ft) from the output rotation speed (V) and the accelerator operation amount (A1) by referring to the first required torque data D1. The controller 41 converts the target traction force (Ft) into T/M required torque.

In step S102, the controller 41 determines the required torque of the work machine 3 (hereinafter referred to as W/I required torque). The W/I required torque is the output torque of the engine 21 required to operate the work machine 3. The W/I required torque increases or decreases according to the amount of work machine operation. The controller 41 determines the W/I required torque from the amount of work machine operation and the discharge pressure of the hydraulic pump 32. For example, the controller 41 stores second required torque data D2. The second required torque data D2 specifies the relationship between the amount of work machine operation (A2) and the required flow rate (Qm) of hydraulic oil. The controller 41 determines the required flow rate (Qm) of hydraulic oil from the amount of work machine operation (A2). The controller 41 calculates the W/I required torque from the required flow rate (Qm) and the discharge pressure of the hydraulic pump 32.

In step S103, the controller 41 determines the target output torque of the engine 21. The controller 41 determines the target output torque of the engine 21 from the T/M required torque and the W/I required torque. For example, the controller 41 determines the target output torque of the engine 21 from the sum of the W/I required torque and the T/M required torque.

In detail, as shown in FIG. 4, the controller 41 stores an upper limit TL of the target output torque. The upper limit TL of the target output torque is set according to the engine speed. If the sum of the W/I required torque and the T/M required torque is equal to or less than the upper limit TL of the target output torque, the controller 41 determines the sum of the W/I required torque and the T/M required torque as the target output torque. If the sum of the W/I required torque and the T/M required torque is greater than the upper limit TL of the target output torque, the controller 41 determines the upper limit TL of the target output torque as the target output torque.

The controller 41 determines the throttle command to the fuel injection device 30 according to the target output torque determined as described above. This controls the output of the engine 21 so that the target output torque is achieved.

When the sum of the W/I required torque and the T/M required torque is greater than the upper limit TL of the target output torque, the controller 41 corrects the T/M required torque and the W/I required torque by distributing the torque between the T/M required torque and the W/I required torque according to a predetermined priority.

For example, as shown in FIG. 4, the controller 41 stores the T/M guaranteed torque. Priority is set in the order of "T/M guaranteed torque," "W/I required torque," and "remaining torque," which is the T/M required torque minus the T/M guaranteed torque. The T/M guaranteed torque has the highest priority, and the remaining torque has the lowest priority.

The controller 41 calculates the remaining torque so that the sum of the T/M guaranteed torque, the W/I required torque, and the remaining torque is equal to the upper limit TL of the target output torque. The controller 41 determines the sum of the T/M guaranteed torque and the remaining torque as the corrected T/M required torque. If the sum of the T/M guaranteed torque and the W/I required torque is greater than the upper limit TL of the target output torque, the controller 41 corrects the W/I required torque so that the sum of the T/M guaranteed torque and the W/I required torque is equal to the upper limit TL of the target output torque. The controller 41 controls the capacity of the hydraulic pump 32 based on the corrected W/I required torque.

In the work machine 1 according to this embodiment, the controller 41 executes output limit control to limit the output of the engine 21 depending on the work situation of the work machine 1. The output limit control will be described below. Figure 5 is a flowchart showing the processing of the output limit control.

As shown in FIG. 5, in step S201, the controller 41 controls the output of the engine 21 in the first control mode. When a predetermined task other than excavation is being performed, the controller 41 controls the output of the engine 21 in the first control mode. In the first control mode, the controller 41 sets the upper limit of the output of the engine 21 to a first upper limit output. The controller 41 converts the first upper limit output of the output of the engine 21 into the output torque of the engine 21 to determine the upper limit TL of the target output torque described above.

Specific operations other than excavation include, for example, travel with a load, travel without a load, and soil dumping. Travel with a load is the operation of traveling with a load loaded in the bucket 12. Travel with a load is the operation of traveling with no load loaded in the bucket 12. Soil dumping is the operation of discharging the load from the bucket 12.

In step S202, the controller 41 acquires status data. The status data indicates the operating status of the work machine 1. The status data includes, for example, the operating position of the FR operating member 42 described above, the boom bottom pressure, and the boom angle.

In step S203, the controller 41 determines the work phase of the work machine based on the operating state of the work machine 1. The controller 41 determines whether the work phase is excavation based on the status data. The controller 41 determines whether the work phase is excavation when the status data satisfies the conditions indicating excavation work. The conditions indicating excavation work are, for example, that the FR operating member 42 is in the forward position, the boom angle is equal to or less than a predetermined angle threshold, and the boom bottom pressure is equal to or greater than a predetermined pressure threshold. If the work phase is a predetermined work other than excavation, the first control mode is maintained in step S201.

If the work phase is excavation, the process proceeds to step S204. In step S204, the controller 41 controls the output of the engine 21 in the second control mode. In the second control mode, the controller 41 reduces the upper limit of the output of the engine 21 more than in the first control mode. In the second control mode, the controller 41 sets the upper limit of the output of the engine 21 to a second upper limit output. The second upper limit output is smaller than the first upper limit output.

The second upper limit output is set to an output of the engine 21 that is sufficient when excavating using the work machine 1. The second upper limit output may be a constant value. Alternatively, the second upper limit output may be variable. The second upper limit output may be manually set by the operator using the input device 45. The controller 41 converts the second upper limit output of the output of the engine 21 into the output torque of the engine 21 to determine the upper limit TL of the target output torque described above.

Figure 6 is a diagram showing the first torque upper limit TL1 and the second torque upper limit TL2 of the target output torque. The first torque upper limit TL1 indicates the upper limit TL of the target output torque calculated from the first upper limit output in the first control mode. The second torque upper limit TL2 indicates the upper limit TL of the target output torque calculated from the second upper limit output in the second control mode. As shown in Figure 6, the second torque upper limit TL2 is smaller than the first torque upper limit TL1. Therefore, in the second control mode, the controller 41 reduces the upper limit TL of the target output torque from the first torque upper limit TL1 to the second torque upper limit TL2.

In step S205, the controller 41 determines whether excavation has ended. For example, the controller 41 determines that excavation has ended when the above-mentioned conditions indicating excavation work are not satisfied. If excavation has ended, in step S201, the controller 41 controls the output of the engine 21 in the first control mode. That is, the controller 41 increases the upper limit of the output of the engine 21 from the first upper limit output to the second upper limit output. If excavation has not ended, the controller 41 maintains the second control mode in step S204.

Figure 7 is a timing chart showing the upper limit of the engine 21 output, which is changed depending on the work situation. In Figure 7, "non-digging" means a specified work other than excavation. As shown in Figure 7, the work machine 1 is performing non-digging work at time T1-T2. In this case, the controller 41 controls the output of the engine 21 in the first control mode, and the upper limit of the engine 21 output is set to the first upper limit output P1.

When the operation is switched from non-digging to excavation at time T2, the controller 41 switches the control mode of the engine 21 from the first control mode to the second control mode. As a result, the controller 41 reduces the upper limit of the output of the engine 21 from the first upper limit output P1 to the second upper limit output P2. At that time, the controller 41 reduces the upper limit of the output of the engine 21 at a predetermined reduction rate. The predetermined reduction rate means the amount of reduction in the upper limit output per unit time. As a result, the upper limit of the output of the engine 21 is gradually reduced from the first upper limit output P1 to the second upper limit output P2 from time T2.

At time T3, when the operation is switched from excavation to non-excavation, the controller 41 switches the control mode of the engine 21 from the second control mode to the first control mode. As a result, the controller 41 increases the upper limit of the output of the engine 21 from the second upper limit output P2 to the first upper limit output P1. At that time, the controller 41 increases the upper limit of the output of the engine 21 at a predetermined increase rate. The predetermined increase rate means the increase amount of the upper limit output per unit time. As a result, the upper limit of the output of the engine 21 is gradually reduced from the second upper limit output P2 to the first upper limit output P1 from time T3.

Similarly, at time T4, when the operation is switched from non-drilling to drilling, the controller 41 switches the control mode of the engine 21 from the first control mode to the second control mode. As a result, the controller 41 reduces the upper limit of the output of the engine 21 from the first upper limit output P1. At time T5, when the operation is switched from drilling to non-drilling, the controller 41 switches the control mode of the engine 21 from the second control mode to the first control mode. As a result, the controller 41 increases the upper limit of the output of the engine 21 toward the first upper limit output P1.

The absolute value of the specified reduction rate is smaller than the absolute value of the specified increase rate. Therefore, when the upper limit of the output of the engine 21 is decreased, the upper limit of the output of the engine 21 changes more slowly than when the upper limit of the output of the engine 21 is increased. In other words, when the upper limit of the output of the engine 21 is increased, the upper limit of the output of the engine 21 changes more quickly than when the upper limit of the output of the engine 21 is decreased.

In the work machine 1 according to the present embodiment described above, when it is determined that the work situation is excavation, the output of the engine 21 is controlled in the second control mode. In the second control mode, the upper limit of the output of the engine 21 is lower than in the first control mode. The first upper limit output in the first control mode is greater than the output of the engine 21 required for excavation, and the second upper limit output in the second control mode is the output of the engine 21 that is sufficient for excavation. Therefore, during excavation, the engine 21 is controlled by the second control mode at an appropriate output according to the load on the work machine 1, thereby improving fuel efficiency.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the invention.

The work machine 1 is not limited to a wheel loader, but may be other machines such as a bulldozer or a motor grader. The work machine 1 may be operable remotely. In that case, the FR operating member 42, the accelerator operating member 43, the work machine operating member 44, and the input device 45 may be disposed outside the work machine 1.

The controller 41 may be composed of multiple controllers. The above-mentioned control processing of the work machine 1 may be distributed and executed by multiple controllers. The control method of the engine 21 is not limited to that of the above-mentioned embodiment and may be changed. The above-mentioned correction of the W/I required torque and correction of the T/M required torque may be omitted.

The output limit control of the engine 21 is not limited to that of the embodiment described above and may be modified. The method of determining whether the work situation is excavation is not limited to that of the embodiment described above and may be modified. For example, the work situation may be determined by an image captured by a camera.

For example, the controller 41 may control the output of the engine 21 in the second control mode during work other than excavation. For example, when the work machine 1 is traveling uphill, the controller 41 may control the output of the engine 21 in the second control mode. The controller 41 may determine whether the work situation is uphill travel from the output rotation speed and the attitude of the vehicle body 2. Alternatively, even when the work machine 1 is traveling uphill, the controller 41 may control the output of the engine 21 in the first control mode.

The control mode of the maximum traction force of the work machine 1 may be manually set. For example, the control mode of the maximum traction force may include a Hi mode and a Lo mode. The controller 41 may control the engine 21 so that the maximum traction force of the work machine 1 is smaller in the Lo mode than in the Hi mode. The above-mentioned output limit control may be executed only when the Hi mode is selected. Alternatively, the output limit control may be executed when either the Hi mode or the Lo mode is selected.

According to the present disclosure, fuel efficiency can be improved in a work machine by controlling the engine with an appropriate output according to the load on the work machine.

2: Vehicle body 3: Work machine 21: Engine 25: Travel device 38: Work machine attitude sensor 41: Controller

Claims (8)

A work machine, comprising:
The car body and
An engine mounted on the vehicle body;
a traveling device mounted on the vehicle body and driven by a driving force from the engine to cause the vehicle body to travel;
a working machine supported movably on the vehicle body and operated by a driving force from the engine;
a sensor for detecting status data indicating an operating status of the traveling device and the working machine;
A controller that controls the engine, the traveling device, and the work machine;
Equipped with
The controller:
acquiring said status data;
determining a work situation of the work machine based on an operating state of the traveling device and the work machine;
When it is determined that the work situation is a predetermined work other than excavation, the output of the engine is controlled in a first control mode;
When the work situation is determined to be the excavation, the output of the engine is controlled in a second control mode;
In the second control mode, an upper limit of the output of the engine is reduced more than in the first control mode.
Working machinery. When switching from the first control mode to the second control mode, the controller gradually reduces an upper limit of the output of the engine at a predetermined reduction rate.
2. The work machine of claim 1. the controller, when switching from the second control mode to the first control mode, gradually increases the upper limit of the output of the engine at a predetermined increase rate.
2. The work machine of claim 1. The controller:
When switching from the first control mode to the second control mode, the upper limit of the output of the engine is gradually reduced at a predetermined reduction rate,
When switching from the second control mode to the first control mode, the upper limit of the output of the engine is gradually increased at a predetermined increase rate,
the absolute value of the predetermined reduction rate is smaller than the absolute value of the predetermined increase rate;
2. The work machine of claim 1. A method for controlling a work machine including a vehicle body, an engine mounted on the vehicle body, a traveling device mounted on the vehicle body and driven by driving force from the engine to cause the vehicle body to travel, and a work implement operably supported on the vehicle body and operated by driving force from the engine, comprising:
Obtaining status data indicating an operating status of the traveling device and the work machine;
determining a work situation of the work machine based on an operating state of the traveling device and the work machine;
When the work situation is determined to be a predetermined work other than excavation, controlling the output of the engine in a first control mode;
When the work situation is determined to be the excavation, controlling the output of the engine in a second control mode;
In the second control mode, an upper limit of the output of the engine is reduced more than in the first control mode.
A method for providing the above. When switching from the first control mode to the second control mode, an upper limit of the output of the engine is gradually reduced at a predetermined reduction rate.
The method according to claim 5. and gradually increasing an upper limit of the output of the engine at a predetermined increase rate when switching from the second control mode to the first control mode.
The method according to claim 5. When switching from the first control mode to the second control mode, gradually reducing an upper limit of the output of the engine at a predetermined reduction rate;
gradually increasing an upper limit of the output of the engine at a predetermined rate of increase when switching from the second control mode to the first control mode;
Equipped with
the absolute value of the predetermined reduction rate is smaller than the absolute value of the predetermined increase rate;
The method according to claim 5.

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