Work machine and method for controlling work machine

Abstract

This work machine is provided with a vehicle body, an engine, a travel device, a work machine, a sensor, and a controller. The sensor detects state data indicating the operating state of the traveling device and the working machine. The controller obtains state data. The controller determines the work situation of the work machine on the basis of the operation states of the travel device and the work machine. When it is determined that the work situation is a predetermined work other than excavation, the controller controls the output of the engine in a first control mode. The controller controls the output of the engine in a second control mode when it is determined that the working situation is excavation. In the second control mode, the controller lowers the upper limit of the output of the engine than in the first control mode.

Description

Technical Field

[0001] The present disclosure relates to a work machine and a method for controlling a work machine. Background Art

[0002] Among working machines such as construction machines, there are working machines that automatically control the output of the engine by detecting the current working stage. For example, in the working machine of Patent Document 1, a controller determines whether the working machine is excavating or traveling uphill. When the working machine is excavating or traveling uphill, the engine is operated at a high output, and when other work is being performed, the engine is operated at a low output.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. WO2005 / 024208 Summary of the invention

[0006] Problems to be solved by the invention

[0007] In the above-mentioned working machine, the engine output is set high in the working situation where the load on the working machine is large, such as excavation or uphill travel. On the other hand, the engine output is limited in the working situation where the load on the working machine is small.

[0008] In recent years, in order to achieve low fuel consumption in working machines, working machines with high-output engines have emerged. The high-output engine produces an output equivalent to that of previous engines at a low engine speed. As a result, the fuel consumption of the working machine can be improved. However, in working machines with high-output engines, there is a possibility that fuel consumption will deteriorate because the engine runs at an output that is excessively high relative to the load on the working machine. The purpose of the present disclosure is to improve fuel consumption in a working machine by controlling the engine with an appropriate output corresponding to the load on the working machine.

[0009] Means for solving problems

[0010] A working machine according to one embodiment of the present disclosure includes a vehicle body, an engine, a travel device, a working machine, 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 a driving force from the engine so that the vehicle body moves. The working machine is supported so as to be movable relative to the vehicle body. The working machine moves according to the driving force from the engine. The sensor detects status data indicating the operating status of the travel device and the working machine. The controller controls the engine, the travel device, and the working machine.

[0011] The controller obtains the status data. The controller determines the working state of the working machine based on the operating states of the travel device and the working machine. When the controller determines that the working state is a predetermined operation other than excavation, the controller controls the output of the engine through the first control mode. When the controller determines that the working state is excavation, the controller controls the output of the engine through the second control mode. In the second control mode, the controller lowers the upper limit of the engine output more than in the first control mode.

[0012] The method involved in other embodiments of the present disclosure is a method for controlling a working machine. The working machine includes a vehicle body, an engine, a travel device, and a working machine. 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, thereby causing the vehicle body to travel. The working machine is supported so as to be movable relative to the vehicle body. The working machine moves according to the driving force from the engine. The method includes: obtaining status data representing the operating status of the travel device and the working machine; determining the operating situation of the working machine based on the operating status of the travel device and the working machine; controlling the output of the engine by a first control mode when it is determined that the operating situation is a prescribed operation other than excavation; controlling the output of the engine by a second control mode when it is determined that the operating situation is excavation; and in the second control mode, lowering the upper limit of the engine output more than in the first control mode.

[0013] Effects of the Invention

[0014] According to the present disclosure, when it is determined that the working situation is excavation, the output of the engine is controlled by the second control mode. In the second control mode, the upper limit of the engine output is lowered compared to the first control mode. Thus, during the excavation operation, the engine is controlled with an appropriate output corresponding to the load on the working machine, thereby improving fuel consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a side view of the working machine according to the embodiment.

[0016] Figure 2 It is a block diagram showing the structure of a working machine.

[0017] Figure 3 It is a block diagram showing a process for determining a target output torque (Torque) of an engine.

[0018] Figure 4 This is a diagram showing torque distribution between the torque requested for the working machine and the torque requested for the transmission.

[0019] Figure 5 : is a flowchart showing the processing of the engine output limitation control.

[0020] Figure 6 : is a graph showing a first torque upper limit and a second torque upper limit of a target output torque of an engine.

[0021] Figure 7 This is a time chart showing the upper limit of the engine output which changes according to the working situation. DETAILED DESCRIPTION

[0022] Hereinafter, one embodiment of the present disclosure will be described with reference to the drawings. Figure 1 1 is a side view of a working machine 1 according to the embodiment. In the present embodiment, the working machine 1 is a wheel loader. Figure 1 As shown, the working machine 1 includes a vehicle body 2 and a working machine 3 .

[0023] 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 as to be rotatable to the left and right. The front vehicle body 2a and the rear vehicle body 2b are connected by a hydraulic cylinder 15. The hydraulic cylinder 15 is extended and retracted, so that the front vehicle body 2a is rotated to the left and right relative to the rear vehicle body 2b.

[0024] The working machine 3 is used for digging, transporting, or dumping operations. The working machine 3 is mounted to the front vehicle body 2a so as to be movable. 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 moved by extending and retracting the hydraulic cylinders 13 and 14.

[0025] Figure 2 is a block diagram showing the structure of the working machine 1. Figure 2 As shown, the working 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 cylinder of the engine 21.

[0026] The first drive system 22 includes a transmission 24 and a travel device 25. The transmission 24 is connected to the engine 21. The transmission 24 transmits the driving force from the engine 21 to the travel device 25. For example, the transmission 24 is an HMT (Hydraulic Mechanical Transmission). The HMT includes a planetary gear mechanism and a hydraulic pump / motor. The HMT can change the speed ratio steplessly by controlling the capacity of the hydraulic pump / motor.

[0027] However, the transmission 24 may be another type of transmission such as an EMT (Electric Mechanical Transmission) or an HST (Hydro-Static Transmission). Alternatively, the transmission 24 may be a transmission including a torque converter and a plurality of speed change gears.

[0028] The travel device 25 is mounted on the vehicle body 2 and is driven by the driving force from the engine 21, so that the vehicle body 2 travels. The travel 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 wheel 28 is provided on the front vehicle body 2a. The rear wheel 29 is provided on the rear vehicle body 2b. The axle 26 transmits the driving force from the transmission 24 to the front wheel 28. The axle 27 transmits the driving force from the transmission 24 to the rear wheel 29.

[0029] 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. Figure 2 In the figure, only one hydraulic pump 32 is shown. However, two or more hydraulic pumps may be connected to the engine 21 via the PTO 31.

[0030] The hydraulic pump 32 is connected to the engine 21 via the PTO 31. The hydraulic pump 32 is driven by the engine 21 to discharge hydraulic oil. The hydraulic oil discharged from the hydraulic pump 32 is supplied to the above-mentioned hydraulic cylinders 13-15. Figure 2 In the figure, only the hydraulic cylinder 13 is shown, and the other hydraulic cylinders 14 and 15 are omitted.

[0031] The control valve 33 controls the flow rate of the hydraulic oil supplied from the hydraulic pump 32 to the hydraulic cylinders 13 to 15. The control valve 33 is, for example, an electromagnetic proportional control valve that is controlled according to an input electrical signal. Alternatively, the control valve 33 may be a pressure proportional control valve that is controlled according to an input pilot pressure.

[0032] The working machine 1 includes an engine sensor 34 and a vehicle speed sensor 35. The engine sensor 34 detects the engine speed. The vehicle speed sensor 35 detects the output speed of the travel device 25. The output speed of the travel device 25 is equivalent to the vehicle speed of the working machine 1. The output speed of the travel device 25 is, for example, the speed of the output shaft of the transmission 24. However, the output speed may also be the speed of other rotating elements in the transmission 24 or located downstream of the transmission 24.

[0033] The working 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.

[0034] The working machine 1 includes a working machine posture sensor 38 and a vehicle body posture sensor 39. The working machine posture sensor 38 detects the posture of the working machine 3. The posture of the working machine 3 includes, for example, a boom angle. The boom angle is the angle of the boom 11 relative to the horizontal direction. The working machine posture sensor 38 is, for example, an angle sensor installed on the boom 11. Alternatively, the working machine posture sensor 38 may also be a stroke sensor that detects the stroke amount of the hydraulic cylinder 13. In this case, the boom angle may also be calculated based on the stroke amount of the hydraulic cylinder 13 detected by the stroke sensor.

[0035] The vehicle posture sensor 39 detects the posture of the vehicle body 2. The posture of the vehicle body 2 includes, for example, a pitch angle and a roll angle of the vehicle body 2. The vehicle posture sensor 39 is, for example, an IMU (Inertial Measurement Unit). Alternatively, the vehicle posture sensor 39 may be a sensor other than an IMU.

[0036] The working 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 also include an auxiliary storage device such as a hard disk or an SSD (solid state drive). The controller 41 stores a program and data for controlling the working machine 1. The controller 41 executes processing for controlling the working machine 1 according to the stored program and data.

[0037] The controller 41 receives a signal indicating the engine speed from the engine sensor 34. The controller 41 receives a signal indicating the output 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 pressure at the bottom of the boom from the cylinder pressure sensor 37. The controller 41 receives a signal indicating the posture of the work machine 3 from the work machine posture sensor 38. The controller 41 receives a signal indicating the posture of the vehicle body 2 from the vehicle body posture sensor 39.

[0038] The controller 41 controls the output of the engine 21 by sending a command signal to the engine 21. The controller 41 switches 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 speed ratio of the transmission 24 by sending a command signal to the transmission 24. The controller 41 controls the working machine 3 by sending a command signal to the hydraulic pump 32 and the control valve 33.

[0039] The working machine 1 includes a FR operating component 42, an accelerator operating component 43, a working machine operating component 44, and an input device 45. The FR operating component 42 can be operated by an operator to switch the working machine 1 between forward and reverse movement. The FR operating component 42 can be operated from a neutral position to a forward position and a reverse position. The FR operating component 42 is, for example, a lever. However, the FR operating component 42 may also be other components such as a switch or a pedal.

[0040] The accelerator operating member 43 can be operated by the operator to control the speed of the working machine 1. The accelerator operating member 43 is, for example, a pedal. However, the accelerator operating member 43 may also be a handle, or other components such as a switch. The working machine operating member 44 can be operated by the operator to control the working machine 3. The working machine operating member 44 is, for example, a handle. However, the working machine operating member 44 may also be other components such as a switch, or other components such as a pedal.

[0041] The input device 45 can be operated by the operator to set the control of the working machine 1. For example, the input device 45 sets the working machine 1 according 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.

[0042] The controller 41 receives a signal indicating the operation position of the FR operating member 42 from the FR operating member 42. The controller 41 switches the forward gear and the reverse gear of the transmission 24 according 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 operation amount of the working machine from the working machine operating member 44. The working machine operation amount is the operation amount of the working machine operating member 44. The controller 41 receives a signal indicating the setting of the working machine 1 from the input device 45.

[0043] Next, a description will be given of a process for controlling the engine 21 executed by the controller 41 . Figure 3 2 is a block diagram showing a process for controlling the engine 21. Figure 3As shown, in step S101, the controller 41 determines the requested torque of the transmission 24 (hereinafter referred to as T / M requested torque). The T / M requested torque is the output torque of the engine 21 requested by the travel device 25 in order to make the working machine 1 travel. The T / M requested torque increases or decreases according to the accelerator operation amount. The controller 41 determines the T / M requested torque mainly based on the accelerator operation amount and the output speed.

[0044] For example, the controller 41 stores the first requested torque data D1. The first requested torque data D1 specifies the relationship between the target traction force (Ft) output to the working machine 1 and the output speed (V) and the accelerator operation amount (A1). The controller 41 refers to the first requested torque data D1 to determine the target traction force (Ft) according to the output speed (V) and the accelerator operation amount (A1). The controller 41 converts the target traction force (Ft) into the T / M requested torque.

[0045] In step S102, the controller 41 determines the requested torque of the working machine 3 (hereinafter referred to as the W / I requested torque). The W / I requested torque is the output torque of the engine 21 requested in order to operate the working machine 3. The W / I requested torque increases or decreases according to the working machine operation amount. The controller 41 determines the W / I requested torque based on the working machine operation amount and the discharge pressure of the hydraulic pump 32. For example, the controller 41 stores the second requested torque data D2. The second requested torque data D2 specifies the relationship between the working machine operation amount (A2) and the requested flow rate (Qm) of the hydraulic oil. The controller 41 determines the requested flow rate (Qm) of the hydraulic oil based on the working machine operation amount (A2). The controller 41 calculates the W / I requested torque based on the requested flow rate (Qm) and the discharge pressure of the hydraulic pump 32.

[0046] 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 based on the T / M request torque and the W / I request torque. For example, the controller 41 determines the target output torque of the engine 21 based on the sum of the W / I request torque and the T / M request torque.

[0047] In detail, Figure 4 As shown, the controller 41 stores the upper limit TL of the target output torque. The upper limit TL of the target output torque is set according to the engine speed. When the sum of the W / I request torque and the T / M request torque is less than the upper limit TL of the target output torque, the controller 41 determines the sum of the W / I request torque and the T / M request torque as the target output torque. When the sum of the W / I request torque and the T / M request 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.

[0048] The controller 41 determines a throttle command to the fuel injection device 30 based on the target output torque determined as described above. As a result, the output of the engine 21 is controlled so as to achieve the target output torque.

[0049] When the sum of the W / I request torque and the T / M request torque is greater than the upper limit TL of the target output torque, the controller 41 distributes torque to the T / M request torque and the W / I request torque according to a predetermined priority, thereby correcting the T / M request torque and the W / I request torque.

[0050] For example, Figure 4 As shown, the controller 41 stores the T / M guaranteed torque. Priority is set in the order of "T / M guaranteed torque", "W / I requested torque", and "remaining torque" obtained by subtracting the T / M guaranteed torque from the T / M requested torque. The T / M guaranteed torque has the highest priority, and the remaining torque has the lowest priority.

[0051] The controller 41 calculates the surplus torque in such a manner that the sum of the T / M guarantee torque, the W / I request torque, and the surplus torque is the upper limit TL of the target output torque. The controller 41 determines the sum of the T / M guarantee torque and the surplus torque as the corrected T / M request torque. When the sum of the T / M guarantee torque and the W / I request torque is greater than the upper limit TL of the target output torque, the controller 41 corrects the W / I request torque in such a manner that the sum of the T / M guarantee torque and the W / I request torque is 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 request torque.

[0052] In the working machine 1 according to the present embodiment, the controller 41 executes output limiting control for limiting the output of the engine 21 according to the working situation of the working machine 1. The output limiting control will be described below. Figure 5 : is a flowchart showing the process of output limit control.

[0053] like Figure 5 As shown, in step S201, the controller 41 controls the output of the engine 21 through the first control mode. When the controller 41 performs a predetermined operation other than excavation, the output of the engine 21 is controlled through the first control mode. In the first control mode, the controller 41 sets the upper limit of the output of the engine 21 to the first upper limit output. The controller 41 determines the upper limit TL of the above-mentioned target output torque by converting the first upper limit output of the output of the engine 21 into the output torque of the engine 21.

[0054] Prescribed operations other than excavation include, for example, loaded travel, unloaded travel, and earth dumping. Loaded travel is a work of traveling with a load piled in the bucket 12. Loaded travel is a work of traveling without a load piled in the bucket 12. Earth dumping is a work of discharging the load from the bucket 12.

[0055] In step S202, the controller 41 acquires state data. The state data indicates the operating state of the working machine 1. The state data includes, for example, the operating position of the FR operating member 42, the boom bottom pressure, and the boom angle.

[0056] In step S203, the controller 41 determines the working situation of the working machine based on the action state of the working machine 1. The controller 41 determines whether the working situation is excavation based on the state data. The controller 41 determines whether the working situation is excavation when the state data satisfies the conditions indicating the excavation operation. The conditions indicating the excavation operation are, for example, that the FR operating member 42 is in the forward position, the boom angle is below a predetermined angle threshold, and the boom bottom pressure is above a predetermined pressure threshold. When the working situation is a predetermined operation other than excavation, the first control mode is maintained in step S201.

[0057] When the working situation is excavation, the process proceeds to step S204. In step S204, the controller 41 controls the output of the engine 21 by the second control mode. In the second control mode, the controller 41 lowers 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 the second upper limit output. The second upper limit output is smaller than the first upper limit output.

[0058] The second upper limit output is set to a sufficient output of the engine 21 when the working machine 1 is used for excavation. The second upper limit output may also be a constant value. Alternatively, the second upper limit output may also be variable. The second upper limit output may also 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, thereby determining the upper limit TL of the above-mentioned target output torque.

[0059] Figure 6 1 is a diagram showing a first torque upper limit TL1 and a second torque upper limit TL2 of the target output torque. The first torque upper limit TL1 shows the upper limit TL of the target output torque calculated according to the first upper limit output in the first control mode. The second torque upper limit TL2 shows the upper limit TL of the target output torque calculated according to the second upper limit output in the second control mode. Figure 6As shown, the second torque upper limit TL2 is smaller than the first torque upper limit TL1. Therefore, 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 the second control mode.

[0060] In step S205, the controller 41 determines whether the excavation is completed. For example, if the above-mentioned conditions indicating the excavation operation are not satisfied, the controller 41 determines that the excavation is completed. If the excavation is completed, in step S201, the controller 41 controls the output of the engine 21 by 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 the excavation is not completed, the second control mode is maintained in step S204.

[0061] Figure 7 2 is a timing chart showing the upper limit of the output of the engine 21 which changes according to the working situation. Figure 7 In the context of the Regulations, “non-excavation” means specified operations other than excavation. Figure 7 As shown, the working machine 1 performs non-excavation work during the time period 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 output of the engine 21 is set to the first upper limit output P1.

[0062] At time T2, if the operation is switched from non-excavation to excavation, 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 this time, the controller 41 reduces the upper limit of the output of the engine 21 at a prescribed reduction rate. The prescribed 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.

[0063] At time T3, if 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 this time, the controller 41 increases the upper limit of the output of the engine 21 at a prescribed increase rate. The prescribed increase rate means the increase in the upper limit output per unit time. As a result, the upper limit of the output of the engine 21 gradually decreases from the second upper limit output P2 to the first upper limit output P1 from time T3.

[0064] Similarly, at time T4, if the operation is switched from non-excavation to excavation, 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, if 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 toward the first upper limit output P1.

[0065] The absolute value of the prescribed decrease rate is smaller than the absolute value of the prescribed increase rate. Thus, when the upper limit of the output of the engine 21 is reduced, 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 reduced.

[0066] In the working machine 1 according to the present embodiment described above, when it is determined that the working situation is excavation, the output of the engine 21 is controlled by the second control mode. In the second control mode, the upper limit of the output of the engine 21 is further reduced compared with the first control mode. The first upper limit output in the first control mode is larger 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 sufficient for excavation. Therefore, during excavation, the engine 21 is controlled by the appropriate output corresponding to the load on the working machine 1 according to the second control mode, thereby improving fuel consumption.

[0067] As mentioned above, although one embodiment of the present invention has been described, the present invention is not limited to the above-mentioned embodiment, and various modifications can be made within the scope not departing from the gist of the invention.

[0068] The working machine 1 is not limited to a wheel loader, and may be other machines such as a bulldozer or a motor grader. The working machine 1 may also be remotely operated. In this case, the FR operating member 42, the accelerator operating member 43, the working machine operating member 44, and the input device 45 may also be arranged outside the working machine 1.

[0069] The controller 41 may also be composed of a plurality of controllers. The control process of the working machine 1 may also be distributed and executed by a plurality of controllers. The control method of the engine 21 is not limited to the above-mentioned embodiment and may also be changed. The correction of the W / I request torque and the correction of the T / M request torque may also be omitted.

[0070] The output limit control of the engine 21 is not limited to the above-mentioned embodiment and may be changed. The method of determining whether the working situation is excavation is not limited to the above-mentioned embodiment and may be changed. For example, the working situation may be determined by an image captured by a camera.

[0071] For example, the controller 41 may control the output of the engine 21 in the second control mode in operations other than excavation. For example, when the working 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 also determine whether the working situation is traveling uphill based on the output speed and the posture of the vehicle body 2. Alternatively, even when the working machine 1 is traveling uphill, the controller 41 may control the output of the engine 21 in the first control mode.

[0072] The control mode of the maximum traction force of the working machine 1 may also be manually settable. For example, the control mode of the maximum traction force may also include a Hi mode and a Lo mode. The controller 41 may also control the engine 21 so that the maximum traction force of the working machine 1 becomes smaller in the Lo mode than in the Hi mode. The above-mentioned output limiting control may also be performed only when the Hi mode is selected. Alternatively, the output limiting control may also be performed when either the Hi mode or the Lo mode is selected.

[0073] Industrial Applicability

[0074] According to the present disclosure, in a working machine, fuel efficiency can be improved by controlling the engine with an appropriate output corresponding to the load on the working machine.

[0075] Description of Reference Numerals

[0076] 2: Car body

[0077] 3: Operating machine

[0078] 21: Engine

[0079] 25: Driving device

[0080] 38: Working machine posture sensor

[0081] 41: Controller.

Claims

1. A working machine having: Vehicle body; an engine, mounted on the vehicle body; a travel 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 movably supported relative to the vehicle body and operated according to a driving force from the engine; a sensor that detects status data indicating the operating status of the travel device and the work machine; and a controller for controlling the engine, the travel device and the working machine, The controller performs the following actions: Obtaining the status data, Based on the operating states of the travel device and the work machine, the working situation of the work machine is determined; When it is determined that the working situation is a predetermined work other than excavation, the output of the engine is controlled in a first control mode; When it is determined that the working situation is the excavation, the output of the engine is controlled in a second control mode; In the second control mode, the upper limit of the output of the engine is lowered more than in the first control mode.

2. The working machine according to claim 1, wherein: The controller gradually reduces the upper limit of the output of the engine at a predetermined reduction rate when switching from the first control mode to the second control mode.

3. The working machine according to claim 1, wherein: The controller gradually increases the 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.

4. The working machine according to claim 1, wherein: 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 the second control mode is switched to the first control mode, the upper limit of the output of the engine is gradually increased at a predetermined increase rate, An absolute value of the prescribed decrease rate is smaller than an absolute value of the prescribed increase rate.

5. A method for controlling a working machine, the working machine comprising: a vehicle body; an engine mounted on the vehicle body; a travel device mounted on the vehicle body and driven by a driving force from the engine so that the vehicle body travels; and a working machine movably supported relative to the vehicle body and moved according to the driving force from the engine, the method comprising: acquiring status data indicating the operating status of the travel device and the work machine; determining the working situation of the working machine based on the operating states of the travel device and the working machine; When it is determined that the working situation is a predetermined work other than excavation, controlling the output of the engine by a first control mode; When it is determined that the working situation is the excavation, controlling the output of the engine by a second control mode; as well as In the second control mode, the upper limit of the output of the engine is lowered more than in the first control mode.

6. The method according to claim 5, comprising: 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.

7. The method according to claim 5, comprising: 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.

8. The method according to claim 5, comprising: gradually reducing the upper limit of the output of the engine at a predetermined reduction rate when switching from the first control mode to the second control mode; and When the second control mode is switched to the first control mode, the upper limit of the output of the engine is gradually increased at a predetermined increase rate, An absolute value of the prescribed decrease rate is smaller than an absolute value of the prescribed increase rate.

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