Work Machine

Abstract

To quickly obtain desired engine power without the labor of an operator and the consumption of waste fuel.SOLUTION: A work machine includes a control device for controlling an engine. The control device calculates target rotational speed of the engine on the basis of a detection result of an operation amount detection device, calculates a time integral value of a difference between the target rotational speed of the engine and actual rotational speed of the engine detected by an engine rotational speed sensor, calculates a rotational speed correction value on the basis of the time integral value, and adds the rotational speed correction value and the target rotational speed to calculate a rotational speed command value. The control device controls the engine on the basis of the rotational speed command value. The control device determines whether the engine is in an operation state or non-operation state, on the basis of the detection result of the operation amount detection device. The control device sets the time integral value to be a prescribed initial value and controls the engine, when it is determined that it has been switched to the operation state from the non-operation state or it is determined that it is in the non-operation state.SELECTED DRAWING: Figure 8A

Description

[Technical field]

[0001] The present invention relates to a work machine. [Background technology]

[0002] There is known a working machine such as a wheel loader that is equipped with a traveling drive device for moving the vehicle body and a working device having a bucket and an arm for excavating soil and sand. In such a working machine, the traveling device and the working device are driven by the power of an engine. The engine is equipped with a fuel injection device. The fuel injection device adjusts the amount of fuel injected, thereby controlling the engine rotation speed and output torque, and generating the power used for work.

[0003] The higher the engine rotation speed, the higher the upper limit of the power that the engine can generate. On the other hand, the higher the engine rotation speed, the worse the fuel efficiency. Therefore, during standby when the required engine power is small, the engine is controlled to have a low rotation speed. On the other hand, during work when the required engine power is large, the engine is controlled to have a high rotation speed in response to the operation by the operator.

[0004] The engine control device sets a target engine speed in response to an operation by an operator, and controls the fuel injection amount based on the deviation between the target engine speed and the actual engine speed (hereinafter referred to as the rotation speed deviation) so that the actual engine speed approaches the target engine speed. Here, the greater the engine load, the greater the rotation speed deviation, and it takes time to eliminate the rotation speed deviation. Therefore, when the engine load is high, it may not be possible to generate the desired engine power quickly.

[0005] In order to generate the desired engine power when the engine load is large, it is conceivable to perform integral control of the fuel injection amount so as to eliminate the rotation speed deviation. However, in a work machine, the fluctuations in the operation amount by the operator and the fluctuations in the work load can be steep and the range of these fluctuations can be large. For this reason, in a work machine, if integral control of the fuel injection amount is performed so as not to cause engine control to become unstable, it takes time to eliminate the rotation speed deviation.

[0006] Patent Document 1 discloses a work machine in which engine rotation speed correction due to load can be set according to the work form and the operator's preference. The work machine described in Patent Document 1 is equipped with a correction means that applies correction to a target rotation speed based on the load of a hydraulic actuator, a control means that controls the engine to achieve the corrected target rotation speed, and a setting dial as an adjustment means for manually adjusting the correction characteristics of the rotation speed by the correction means. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 7-113252 Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the technology described in Patent Document 1, it is necessary to readjust the correction characteristics according to the preferences of each operator every time the operator changes. Also, if the operator lacks skill, it is difficult to appropriately adjust the correction characteristics. As a result, there is a risk that the desired power cannot be obtained, or that fuel efficiency will deteriorate due to the generation of more power than necessary.

[0009] The present invention has been made to solve these technical problems, and has an object to provide a work machine that is able to quickly obtain the desired engine power without requiring the operator to take the time and effort and without wasting fuel. [Means for solving the problem]

[0010] A working machine according to one aspect of the present invention includes a vehicle body, an engine mounted on the vehicle body, a traveling drive device for driving wheels provided on the vehicle body, a hydraulic pump driven by the engine, a hydraulic cylinder which is expanded and contracted by hydraulic oil discharged from the hydraulic pump, and a work device having a driven member which is moved in accordance with the expansion and contraction of the hydraulic cylinder, an operation device for operating at least one of the traveling drive device and the work device, an operation amount detection device which detects an operation amount of the operation device, an engine rotation speed sensor which detects an actual rotation speed of the engine, and a control device which controls the engine, in which the control device calculates a target rotation speed of the engine based on a detection result of the operation amount detection device, and detects the actual rotation speed of the engine. a time integral value of the difference between a target rotation speed of a gin and an actual rotation speed of the engine detected by the engine rotation speed sensor, a rotation speed correction value based on the calculated time integral value, a rotation speed command value for the engine by adding the calculated rotation speed correction value to the target rotation speed of the engine, and controlling the engine based on the calculated engine rotation speed command value; and a determination is made based on a detection result of the operation amount detection device as to whether the operation device is in an operating state in which it is operated, or in a non-operated state in which it is not operated, and when it is determined that the operating state has been switched from the non-operated state to the operated state or when it is determined that the operation device is in the non-operated state, the time integral value is set to a predetermined initial value and the engine is controlled. Effect of the Invention

[0011] According to the present invention, it is possible to provide a work machine that is capable of quickly obtaining a desired engine power without requiring the operator to do anything and without wasting fuel. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a side view of a wheel loader. [Diagram 2] FIG. 2 is a system configuration diagram of the wheel loader. [Diagram 3] FIG. 3 is a diagram for explaining a basic transport operation of a wheel loader. [Figure 4] FIG. 4 is a diagram for explaining the excavation work. [Diagram 5] FIG. 5 is a functional block diagram of the main controller. [Figure 6] FIG. 6 is a block diagram illustrating a method for calculating a target engine rotation speed by the target speed calculation unit. [Figure 7] FIG. 7 is a diagram showing an example of a correlation map showing the relationship between the engine load and the rotation speed deviation. [Figure 8A] FIG. 8A is a flowchart of the engine control executed by the main controller. [Figure 8B] FIG. 8B is a flowchart of the determination flag setting process shown in the flowchart of FIG. 8A. [Figure 9] FIG. 9 is a diagram showing time series changes in the parameters (accelerator operation amount, work operation amount, rotational speed command value, actual engine rotational speed, and engine power) of the wheel loader 1 according to the first embodiment. [Figure 10] FIG. 10 is a flowchart of engine control executed by the main controller according to the second modification. [Figure 11] FIG. 11 is a flowchart of a determination flag setting process executed by the main controller according to the third modification. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the description of the drawings, the same elements are given the same reference numerals, and duplicated description will be omitted. In this embodiment, an example will be described in which the work machine is an electrically driven wheel loader. Note that in this embodiment, a wheel loader equipped with a hybrid system using an engine and a generator motor as a drive source will be taken as an example, but the present invention may also be applied to a wheel loader equipped with a system using an engine alone as a drive source. In the following description, the up / down, left / right, front / rear directions and positions are based on the normal use state of the work machine, i.e., a state in which the traveling gear is grounded.

[0014] First Embodiment A wheel loader 1 according to a first embodiment of the present invention will be described with reference to Figures 1 to 9. Figure 1 is a side view of the wheel loader 1. As shown in Figure 1, the wheel loader 1 comprises a vehicle body 8 on which an electric travel drive unit 45 is mounted, and an articulated working device 6 attached to the front of the vehicle body 8. The vehicle body 8 is of an articulated steering type (vehicle body articulating type), and has a front vehicle body 8A, a rear vehicle body 8B, and a center joint 10 that connects the front vehicle body 8A and the rear vehicle body 8B.

[0015] A working device 6 is attached to the front body 8A. A cab 12 and an engine room 16 are arranged in the rear body 8B. A seat for an operator and operating devices operated by the operator are provided in the cab 12. The engine room 16 is equipped with an engine 20 (see FIG. 2), hydraulic pumps 30A, 30B, 30C (see FIG. 2) driven by the engine 20, and hydraulic equipment such as valves.

[0016] The working device 6 has a lift arm (hereinafter simply referred to as arm) 2 attached to the front vehicle body 8A so as to be rotatable in the vertical direction, a hydraulic cylinder (hereinafter also referred to as arm cylinder) 4 that drives the arm 2, a bucket 3 attached to the tip of the arm 2 so as to be rotatable in the vertical direction, and a hydraulic cylinder (hereinafter also referred to as bucket cylinder) 5 that drives the bucket 3. The arm 2, which is a driven member, is moved in response to the extension and retraction movement of the arm cylinder 4. The bucket 3, which is a driven member, is moved in response to the extension and retraction movement of the bucket cylinder 5. The arm 2 and the arm cylinder 4 are provided one each on the left and right sides of the front vehicle body 8A. In this embodiment, a Z-link type (bell crank type) link mechanism is adopted as a link mechanism for operating the bucket 3.

[0017] The wheel loader 1 is equipped with a traveling drive device 45 that drives the wheels 7 provided on the vehicle body 8. The traveling drive device 45 includes a traveling motor 43 and a traveling device 11 to which traveling drive force is provided from the traveling motor 43. The traveling device 11 has front wheels 7A which are wheels 7 attached to the front vehicle body 8A, rear wheels 7B which are wheels 7 attached to the rear vehicle body 8B, and a power transmission device that transmits power from the traveling motor 43 to the wheels 7. The power transmission device is composed of an axle, a differential device, a propeller shaft, etc.

[0018] The traveling motor 43 is an electric motor that drives the wheels 7 of the traveling device 11. The traveling motor 43 is rotationally driven by electric power generated by the generator motor 40, which is rotated by the power of the engine 20.

[0019] The wheel loader 1 is steered by a steering device 22 having a pair of left and right hydraulic cylinders (hereinafter also referred to as steering cylinders) 15 provided to connect the front vehicle body 8A and the rear vehicle body 8B.

[0020] Fig. 2 is a system configuration diagram of the wheel loader 1. As shown in Fig. 2, the wheel loader 1 includes an engine 20, a fuel injection device 23 that supplies fuel to the engine 20, a generator motor 40 mechanically connected to the engine 20, hydraulic pumps 30A, 30B, and 30C mechanically connected to the engine 20 and the generator motor 40, a working device 6 driven by hydraulic oil discharged from the hydraulic pump 30A, a front control unit 31 that controls the operation of the working device 6, a braking device 21 driven by hydraulic oil discharged from the hydraulic pump 30B, a brake control unit 32 that controls the operation of the braking device 21, a steering device 22 driven by hydraulic oil discharged from the hydraulic pump 30C, a steering control unit 33 that controls the steering device 22, and a traveling drive device 45 driven by electric power generated by the generator motor 40.

[0021] The working device 6 and the traveling drive device 45 are driven independently of each other by the power of the engine 20. The engine 20, which is a prime mover, is configured by an internal combustion engine such as a diesel engine. The generator motor 40 rotates by the torque output from the engine 20 and functions as a generator that generates electricity.

[0022] The hydraulic pumps 30A, 30B, and 30C are driven by the torque output by the engine 20 to discharge hydraulic oil. When the generator motor 40 functions as an electric motor, the hydraulic pumps 30A, 30B, and 30C are driven by the torque output by the engine 20 and the generator motor 40.

[0023] The hydraulic cylinders 4, 5, 15, 17, and 18 are expanded and contracted by hydraulic oil (pressurized oil) discharged from a hydraulic pump 30A which is rotated by torque output from an engine 20 (see FIG. 2).

[0024] The front control unit 31 controls the pressure, flow rate, and direction of the hydraulic oil supplied from the hydraulic pump 30A to the arm cylinder 4 and the bucket cylinder 5. This controls the extension and retraction operations of the arm cylinder 4 and the bucket cylinder 5. The brake control unit 32 controls the pressure, flow rate, and direction of the hydraulic oil supplied from the hydraulic pump 30B to the brake cylinder 17 and the parking brake cylinder 18. This controls the extension and retraction operations of the brake cylinder 17 and the parking brake cylinder 18. The steering control unit 33 controls the pressure, flow rate, and direction of the hydraulic oil supplied from the hydraulic pump 30C to the steering cylinder 15. This controls the extension and retraction operation of the steering cylinder 15.

[0025] The wheel loader 1 is equipped with a main controller 100 which is a control device that controls the entire vehicle, an engine controller 120 which controls the fuel injection device 23 based on an engine rotation speed command from the main controller 100, the fuel injection device 23 which controls the fuel injection amount based on a fuel injection amount command from the engine controller 120, a generator motor inverter (hereinafter referred to as the power generation inverter) 41 which controls the generator motor 40 based on a power generation voltage command input from the main controller 100, a traveling motor inverter (hereinafter referred to as the traveling inverter) 42 which controls the torque of the traveling motor 43 based on a traveling drive torque command input from the main controller 100, and various operating devices (51-57) provided in the operator's cab 12.

[0026] Provided within the cab 12 are a forward / reverse switch 51 which is a forward / reverse switching device for switching the vehicle body 8 between forward (F), standby (N), and reverse (R), an arm operation device 52 which operates the arm cylinder 4 (arm 2) of the working device 6, a bucket operation device 53 which operates the bucket cylinder 5 (bucket 3) of the working device 6, an accelerator operation device 56 which operates the traveling drive device 45, a brake operation device 57 which operates the brake cylinder 17, a parking brake operation device 54 which operates the parking brake cylinder 18, and a steering operation device 55 which operates the pair of left and right steering cylinders 15. For ease of explanation, the operation devices 52, 53 of the working device 6 and the operation device 56 of the traveling drive device 45 are collectively referred to as the operation device 50.

[0027] The arm operation device 52 includes an arm operation lever and an arm operation amount sensor 52a that detects the operation amount of the arm operation lever (hereinafter also referred to as the arm operation amount). The bucket operation device 53 includes a bucket operation lever and a bucket operation amount sensor 53a that detects the operation amount of the bucket operation lever (hereinafter also referred to as the bucket operation amount). The accelerator operation device 56 includes an accelerator pedal and an accelerator operation amount sensor 56a that detects the operation amount of the accelerator pedal (hereinafter also referred to as the accelerator operation amount). The brake operation device 57 includes a brake pedal and a brake operation amount sensor 57a that detects the operation amount of the brake pedal (hereinafter also referred to as the brake operation amount). The steering operation device 55 includes a steering wheel and a steering operation amount sensor 55a that detects the operation amount of the steering wheel (hereinafter also referred to as the steering operation amount). The arm operation amount sensor 52a, the bucket operation amount sensor 53a, the accelerator operation amount sensor 56a, the brake operation amount sensor 57a, and the steering operation amount sensor 55a are, for example, potentiometers that output a voltage according to the operation position of an operating member (operation lever or pedal) to the main controller 100.

[0028] The main controller 100 is composed of a microcomputer having a CPU (Central Processing Unit) 101 as an operating circuit, a ROM (Read Only Memory) 102 and a RAM (Random Access Memory) 103 as storage devices, an input interface 104, an output interface 105, and other peripheral circuits. The engine controller 120 is also composed of a microcomputer having an operating circuit, a storage device, an input / output interface, and the like, similar to the main controller 100. The main controller 100 and the engine controller 120 may each be composed of one microcomputer or multiple microcomputers.

[0029] The ROM 102 of the main controller 100 is a non-volatile memory such as an EEPROM, and stores programs capable of executing various calculations. In other words, the ROM 102 of the main controller 100 is a storage medium capable of reading programs that realize the functions of this embodiment. The RAM 103 is a volatile memory, and is a work memory that directly inputs and outputs data to and from the CPU 101. The RAM 103 temporarily stores necessary data while the CPU 101 is executing the programs. The main controller 100 may further include a storage device such as a flash memory, a hard disk drive, or the like.

[0030] The CPU 101 is a processing device that loads a program stored in the ROM 102 into the RAM 103 and executes calculations thereon, and performs predetermined calculations on signals received from the input interface 104, the ROM 102, and the RAM 103 in accordance with the program.

[0031] Operation signals from various operating devices (51 to 57) and sensor signals from various sensors are input to the input interface 104. The input interface 104 converts the input signals into data that can be calculated by the CPU 101. The output interface 105 generates an output signal according to the calculation result by the CPU 101, and outputs the signal to the front control unit 31, the brake control unit 32, the steering control unit 33, the power generation inverter 41, the traveling inverter 42, the engine controller 120, etc.

[0032] The main controller 100 comprehensively controls the front control unit 31, the brake control unit 32, the steering control unit 33, the power generation inverter 41, the driving inverter 42, and the engine controller 120 based on operation signals input from various operating devices and sensor signals input from various other sensors.

[0033] The operation signals input to the main controller 100 include the accelerator operation amount detected by the accelerator operation amount sensor 56a, the brake operation amount detected by the brake operation amount sensor 57a, the arm operation amount detected by the arm operation amount sensor 52a, the bucket operation amount detected by the bucket operation amount sensor 53a, the steering operation amount detected by the steering operation amount sensor 55a, and a signal output from the forward / reverse switch 51 indicating the operation position of the forward / reverse switch 51.

[0034] The sensor signals input to the main controller 100 include a signal representing the angle detected by an arm relative angle sensor 62 provided on a connecting shaft connecting the vehicle body 8 and the arm 2, and a signal representing the angle detected by a bucket relative angle sensor 63 provided on a connecting shaft connecting the arm 2 and the bucket 3. The arm relative angle sensor 62 is a potentiometer that detects the relative angle (tilt angle) of the arm 2 with respect to the vehicle body 8 and outputs a signal representing the detected angle to the main controller 100. The bucket relative angle sensor 63 is a potentiometer that detects the relative angle (tilt angle) of the bucket 3 with respect to the arm 2 and outputs a signal representing the detected angle to the main controller 100. Since the angle of the vehicle body 8 with respect to the ground (traveling surface) is constant, it can be said that the angle detected by the arm relative angle sensor 62 corresponds to the relative angle (tilt angle) of the arm 2 with respect to the ground.

[0035] Furthermore, the sensor signals input to the main controller 100 include a signal indicating the vehicle speed (traveling speed of the vehicle) detected by a vehicle speed sensor 61. The vehicle speed sensor 61 detects the vehicle speed of the wheel loader 1, and outputs a signal indicating the detected vehicle speed to the main controller 100. Furthermore, the sensor signals input to the main controller 100 include signals indicating the rotational speeds of the engine 20, the generator motor 40, the hydraulic pumps 30A, 30B, 30C, and the traveling motor 43 detected by a plurality of rotational speed sensors, the discharge pressures of the hydraulic pumps 30A, 30B, 30C detected by first, second, and third discharge pressure sensors 71, 72, 73, and signals indicating the pressure (load pressure) of the hydraulic cylinders detected by a cylinder pressure sensor (not shown), etc.

[0036] The multiple rotation speed sensors include an actual rotation speed of the engine 20 (hereinafter, actual engine rotation speed N E_A The engine speed sensor 64 is, for example, a rotary encoder provided on the output shaft of the engine 20, and detects the actual engine speed N E_AThe main controller 100 outputs a signal representing the actual engine rotation speed N to the engine controller 120. Note that the engine rotation speed sensor 64 is not limited to detecting the rotation speed of the output shaft of the engine 20, but may detect the rotation speed of any shaft constituting the power transmission device. In this case, the main controller 100 calculates the actual engine rotation speed N based on the detection result of the engine rotation speed sensor 64. E_A Calculate the following.

[0037] In the illustrated example, the engine speed sensor 64 is connected to the main controller 100, but may be connected to the engine controller 120. In this case, the main controller 100 receives the actual engine speed N E_A is acquired via the engine controller 120.

[0038] As will be described later, the main controller 100 determines a target rotation speed N of the engine 20 (hereinafter, also referred to as a target engine rotation speed) based on the accelerator operation amount, the arm operation amount, the bucket operation amount, etc. E_T The main controller 100 calculates the target rotation speed N E_T Based on this, the rotation speed command value N E_C The main controller 100 calculates the actual engine speed N E_A to the engine controller 120.

[0039] The engine controller 120 receives the rotation speed command value N E_C and the actual engine speed N detected by the engine speed sensor 64. E_A Compared with the actual engine speed N E_A is the rotation speed command value N E_C The fuel injector 23 controls the fuel injection amount based on a fuel injection command output from the engine controller 120 to operate the engine 20. For example, in this embodiment, the engine controller 120 controls the fuel injection amount based on the actual engine rotation speed NE_A Compared to the rotation speed command value N E_C When is large, the actual engine speed N E_A and the rotation speed command value N E_C The fuel injection amount is gradually increased until the difference between the fuel injection amount and the actual fuel injection amount becomes small.

[0040] In this way, the main controller 100, the engine controller 120, and the fuel injector 23 cooperate to configure a control device that controls the operation of the engine 20. The control of the engine 20 will be described in detail later.

[0041] The main controller 100 outputs a front control command based on the operation direction and operation amount of the arm operation device 52 and the bucket operation device 53. The front control unit 31 adjusts the pressure, flow rate, and direction of the hydraulic oil discharged from the hydraulic pump 30A based on the front control command from the main controller 100, and operates the arm cylinder 4 and the bucket cylinder 5. The front control unit 31 has a directional control valve that controls the flow of the hydraulic oil discharged from the hydraulic pump 30A, and a solenoid valve that generates pilot pressure input to a pilot chamber of the directional control valve, etc.

[0042] The main controller 100 outputs a brake control command based on the operation amount of the brake operating device 57 and the operation position of the operation switch of the parking brake operating device 54. The brake control unit 32 adjusts the pressure, flow rate and direction of the hydraulic oil discharged from the hydraulic pump 30B based on the brake control command from the main controller 100, and operates the brake cylinder 17 and the parking brake cylinder 18. The brake control unit 32 has a directional control valve that controls the flow of the hydraulic oil discharged from the hydraulic pump 30B, and a solenoid valve that generates pilot pressure input to a pilot chamber of the directional control valve, etc.

[0043] The main controller 100 outputs a steering control command based on the operation direction and operation amount of the steering wheel of the steering operation device 55. The steering control unit 33 adjusts the pressure, flow rate and direction of the hydraulic oil discharged from the hydraulic pump 30C based on the steering control command from the main controller 100, and operates the steering cylinder 15. The steering control unit 33 has a directional control valve that controls the flow of the hydraulic oil discharged from the hydraulic pump 30C, and a solenoid valve that generates pilot pressure input to a pilot chamber of the directional control valve, etc.

[0044] The power generation inverter 41 and the traveling inverter 42 are connected by a DC section (DC bus) 44. It should be noted that the wheel loader 1 according to this embodiment does not include an electricity storage device connected to the DC section 44. The power generation inverter 41 controls the bus voltage of the DC section 44 by utilizing power supplied from the generator motor 40, based on a power generation voltage command from the main controller 100. The traveling inverter 42 drives the traveling motor 43 by utilizing the power of the DC section 44, based on a traveling drive torque command from the main controller 100.

[0045] In this embodiment, the hydraulic pumps 30A, 30B, and 30C are driven by the torque output by the engine 20, and the working device 6, the brake device 21, and the steering device 22 are driven by the hydraulic oil discharged from the hydraulic pumps 30A, 30B, and 30C. Also, in this embodiment, the generator motor 40 is driven by the torque output by the engine 20, and the traveling motor 43 is driven by the electric power generated by the generator motor 40.

[0046] When the arm operation lever of the arm operation device 52 is operated, the arm 2 rotates vertically (moves up and down) due to the extension and contraction of the arm cylinder 4. When the bucket operation lever of the bucket operation device 53 is operated, the bucket cylinder 5 rotates vertically (tilts or dumps).

[0047] When the steering wheel of the steering operation device 55 is operated, the front body 8A is bent (steered) left and right about the center joint 10 relative to the rear body 8B in accordance with the extension and contraction of the steering cylinder 15. When the accelerator pedal of the accelerator operation device 56 is operated, the wheels 7 are rotated by the drive of the traveling motor 43, and the wheel loader 1 travels.

[0048] When the forward / reverse switch 51 is set to forward (F) and the accelerator pedal of the accelerator operation device 56 is depressed, the wheels 7 rotate in the forward direction and the vehicle body 8 travels forward. When the forward / reverse switch 51 is set to reverse (R) and the accelerator pedal of the accelerator operation device 56 is depressed, the wheels 7 rotate in the reverse direction and the vehicle body 8 travels backward. Note that when the forward / reverse switch 51 is set to standby (N), the wheels 7 do not rotate and the vehicle body 8 does not travel, even if the accelerator pedal of the accelerator operation device 56 is depressed.

[0049] Next, the operation of the wheel loader 1 will be described with reference to Figures 3 and 4. Figure 3 is a diagram for explaining the basic transport operation of the wheel loader 1, and Figure 4 is a diagram for explaining the excavation operation. In the transport operation, the wheel loader 1 performs an excavation operation of excavating an excavation target 91 such as earth and sand or minerals, and then performs a loading operation of transporting the excavated material and loading it onto a loading target 92 such as a dump truck. Figure 3 shows V-shape loading, which is one method for performing this transport operation.

[0050] As shown by arrow X1 in FIG. 3 and FIG. 4(a), the operator operates the accelerator operation device 56 to move the wheel loader 1 forward toward an excavation target 91 such as natural ground, and as shown in FIG. 4(b), the operator causes the bucket 3 to penetrate into the excavation target 91. The operator operates the arm operation device 52 and the bucket operation device 53 to raise the arm 2 and put soil, minerals, etc. into the bucket 3. Thereafter, the operator operates the bucket operation device 53 to tilt the bucket 3 as shown in FIG. 4(c). At this time, the operator operates the bucket operation device 53 to scoop up the bucket 3 toward himself so as not to spill the soil, minerals, etc. that have entered the bucket 3. This completes the excavation work.

[0051] After the excavation work is completed, the operator moves the wheel loader 1 backward to return to the original position, as shown by the arrow X2 in FIG. 3. After that, the operator moves the wheel loader 1 forward toward the loading target 92, such as a dump truck, as shown by the arrow Y1 in FIG. 3, while raising the arm 2. The operator stops the wheel loader 1 in front of the loading target 92. Note that in FIG. 3, the wheel loader 1 in a state of being stopped in front of the loading target 92 is shown by a dashed line. After that, the operator operates the bucket operation device 53 to perform a dump operation of the bucket 3, thereby releasing the transported material in the bucket 3 onto the loading platform of the loading target 92. As a result, the transported material in the bucket 3 is loaded onto the loading platform of the loading target 92, and the loading work is completed. After the loading work is completed, the operator moves the wheel loader 1 backward to return to the original position, as shown by the arrow Y2 in FIG. 3.

[0052] This series of operations including excavation and loading is called "V-shape loading" because it is performed while tracing a V-shaped trajectory, and is performed repeatedly. V-shape loading accounts for the majority of the total working time of the wheel loader 1. For this reason, in order to improve the working efficiency of the wheel loader 1, it is effective to generate a desired engine power regardless of the engine load during V-shape loading. Here, working efficiency (t / h) means the weight (t) of transported goods loaded onto the loading target 92 per a given time (h).

[0053] The magnitude of the engine power is basically determined by the actual engine speed N E_A The higher the actual engine speed N E_A The higher the rotation speed command value N E_C On the other hand, during work, the main controller 100 determines the rotation speed command value N at which the engine power required for work (i.e., the desired engine power) is obtained based on the amount of operation of the accelerator operation device 56, the arm operation device 52, and the bucket operation device 53 by the operator. E_C to the engine controller 120. The engine controller 120 outputs this rotation speed command value N E_C Actual engine speed N E_A The amount of fuel injected by the fuel injector 23 is adjusted so that the amounts match, thereby generating the desired engine power.

[0054] Actual engine speed N E_A is the rotation speed command value N E_C When the actual engine speed N is below the required speed and the required engine power is not being generated, fuel efficiency improves but work efficiency decreases. E_A is the rotation speed command value N E_C When the actual engine speed N exceeds the actual engine speed N and more engine power than necessary is being generated, the work efficiency does not change but the fuel consumption decreases. E_A Rotation speed command value N E_C It is important to quickly align the

[0055] The engine controller 120 determines the rotation speed command value N E_C and actual engine speed N E_A The main controller 100 determines the amount of fuel injected by the fuel injection device 23 based on the difference between the target engine rotation speed N E_T Without correcting, the rotation speed command value N E_CIn this case, the larger the engine load (i.e., the more fuel injection amount is required), the larger the actual engine rotation speed N E_A is the rotation speed command value N E_C (= Target engine speed N E_T ) is stabilized at a low value. This may result in a decrease in work efficiency. To prevent this, the engine controller 120 executes integral control to gradually increase the fuel injection amount, and the rotation speed command value N E_C and actual engine speed N E_A However, in the above-mentioned transportation work, the fluctuations in the amount of operation of the operation device 50 by the operator and the fluctuations in the engine load are steep and very large. For this reason, the integral control of the fuel injection amount alone cannot reduce the difference between the rotation speed command value N E_C (= Target engine speed N E_T ) and actual engine speed N E_A The difference between the two cannot be reduced quickly, and there is room for improvement.

[0056] Here, the target engine speed N E_T and actual engine speed N E_A The difference between the target engine speed N E_T and actual engine speed N E_A The rotation speed command value N E_C However, if the actual engine load is lower than expected, the actual engine speed N E_A If the actual engine load is higher than expected, the target engine speed N E_T than the actual engine speed N E_A will become lower and work efficiency will deteriorate.

[0057] In addition, the gain of the integral control of the fuel injection amount by the engine controller 120 is increased, and the rotation speed command value N E_C Actual engine speed N E_A However, this method has the disadvantage that the smaller the work load, the slower the actual engine speed NE_A This will increase the overshoot, which may cause the engine control to become unstable.

[0058] Therefore, the inventors of the present application have conducted extensive research and have found that the target engine rotation speed N E_T When increases, the target engine speed N E_T and actual engine speed N E_A In order to quickly eliminate the difference between the target engine speed N E_T and actual engine speed N E_A The target engine speed N is based on the time integral of the difference E_T It has been found that by correcting the rotation speed command value N E_C The contents of the calculation process will be described in detail below.

[0059] Fig. 5 is a functional block diagram of the main controller 100. As shown in Fig. 5, the main controller 100 executes a program stored in the ROM 102 to function as a target speed calculation unit 110, a deviation calculation unit 111, an operation state determination unit 112, a correction value calculation unit 113, and a command value calculation unit 114.

[0060] The target speed calculation unit 110 calculates the target engine rotation speed N E_T In this embodiment, the target speed calculation unit 110 calculates the target engine rotation speed N E_T The operation amount detection device 150 includes the arm operation amount sensor 52a, the bucket operation amount sensor 53a, the accelerator operation amount sensor 56a, the brake operation amount sensor 57a, and the steering operation amount sensor 55a described above. The discharge pressure detection device 151 includes the first discharge pressure sensor 71, the second discharge pressure sensor 72, and the third discharge pressure sensor 73 described above.

[0061] Referring to FIG. 6, the target engine speed N E_T An example of a method for calculating the target engine rotation speed N E_T 6 is a block diagram for explaining a calculation method of the target speed calculation unit 110. As shown in FIG. 6, the target speed calculation unit 110 has a traveling required power calculation unit 121, a first pump required power calculation unit 122, a second pump required power calculation unit 123, a third pump required power calculation unit 124, a maximum value selection unit 125, an addition unit 126, and a target speed calculation unit 127.

[0062] The traveling demand power calculation unit 121 calculates the traveling demand power based on the rotation speed of the traveling motor 43 detected by the motor speed sensor 58 and the accelerator operation amount detected by the accelerator operation amount sensor 56a. A traveling demand power table used for calculating the traveling demand power is stored in the ROM 102 of the main controller 100. The traveling demand power table stores a plurality of power curves corresponding to the accelerator operation amount so that the power of the traveling motor 43 increases or decreases according to an increase or decrease in the accelerator operation amount. The traveling demand power table is set so that the larger the accelerator operation amount, the larger the traveling demand power becomes, and the faster the rotation speed of the traveling motor 43, the smaller the traveling demand power becomes.

[0063] The traveling power requirement calculation unit 121 selects a power curve corresponding to the magnitude of the accelerator operation amount, and calculates the traveling power requirement based on the rotation speed of the traveling motor 43. For example, when the accelerator operation device 56 is fully operated, the traveling power requirement calculation unit 121 selects the solid power curve, and calculates the traveling power requirement based on the rotation speed of the traveling motor 43 by referring to the selected power curve.

[0064] The first pump required power calculation unit 122 has a pump required flow rate calculation unit 122a and a multiplication unit 122b. The pump required flow rate calculation unit 122a calculates the pump required flow rate of the hydraulic pump 30A based on the arm operation amount and bucket operation amount detected by the arm operation amount sensor 52a and bucket operation amount sensor 53a of the operation amount detection device 150, and the discharge pressure of the hydraulic pump 30A detected by the first discharge pressure sensor 71 of the discharge pressure detection device 151. The arm operation amount and bucket operation amount are also collectively referred to as the lever operation amount.

[0065] A required flow rate table used for calculating the pump required flow rate of the hydraulic pump 30A is stored in the ROM 102 of the main controller 100. The required flow rate table is set so that the pump required flow rate increases from the minimum discharge flow rate in response to an increase in the lever operation amount.

[0066] The pump required flow rate calculation unit 122a refers to a required flow rate table and calculates the pump required flow rate based on the lever operation amount. The pump required flow rate table includes a table based on the arm operation amount and a table based on the bucket operation amount, and the larger of the flow rates determined by each table is determined as the pump required flow rate.

[0067] The multiplication unit 122b multiplies the pump required flow rate of the hydraulic pump 30A calculated by the pump required flow rate calculation unit 122a, the discharge pressure of the hydraulic pump 30A detected by the first discharge pressure sensor 71 of the discharge pressure detection device 151, and a coefficient for unit conversion to calculate the required power of the hydraulic pump 30A.

[0068] Although not shown, the second pump required power calculation unit 123 has a function similar to that of the first pump required power calculation unit 122, and calculates the required power of the hydraulic pump 30B based on the brake operation amount detected by the brake operation amount sensor 57a of the operation amount detection device 150 and the discharge pressure of the hydraulic pump 30B detected by the second discharge pressure sensor 72 of the discharge pressure detection device 151.

[0069] Although not shown, the third pump required power calculation unit 124 has a function similar to that of the first pump required power calculation unit 122, and calculates the required power of the hydraulic pump 30C based on the steering operation amount detected by the steering operation amount sensor 55a of the operation amount detection device 150 and the discharge pressure of the hydraulic pump 30C detected by the third discharge pressure sensor 73 of the discharge pressure detection device 151.

[0070] The maximum value selection unit 125 selects the maximum of the required power of the hydraulic pump 30A calculated by the first pump required power calculation unit 122, the required power of the hydraulic pump 30B calculated by the second pump required power calculation unit 123, and the required power of the hydraulic pump 30C calculated by the third pump required power calculation unit 124, and determines the selected required power as the work required power.

[0071] The adder 126 adds the required traveling power calculated by the required traveling power calculation unit 121 and the required work power selected by the maximum value selection unit 125 to calculate the required engine power.

[0072] The target speed calculation unit 127 calculates the target engine rotation speed N E_T The ROM 102 of the main controller 100 stores the target engine rotation speed N E_T The speed table used to calculate the target engine speed N E_T is the minimum rotation speed N E_T_min The target speed calculation unit 127 refers to the speed table and calculates the target engine rotation speed N E_T Calculate.

[0073] In this way, the target speed calculation unit 110 calculates the target engine rotation speed N so as to generate engine power that satisfies the total value of the travel demand power and the work demand power as much as possible. E_T Determine.

[0074] As shown in FIG. 5, the deviation calculation unit 111 calculates the target engine rotation speed N E_T and actual engine speed N E_A The deviation of the rotation speed from Δ Calculate the following. N Δ =N E_T -N E_A (1) Target engine speed N E_T is calculated by the target speed calculation unit 110, and the actual engine rotation speed N E_A is detected by the engine speed sensor 64.

[0075] The operation state determination unit 112 determines whether the operation device 50 is in an operation state in which the operation device 50 is being operated, or in a non-operation state in which the operation device 50 is not being operated, based on the detection result of the operation amount detection device 150. The operation state determination unit 112 sets a determination flag FL to on or off based on the amount of operation of the operation device 50, and determines whether or not it is in an operation state (working state) based on the setting state of the determination flag FL. The operation state determination unit 112 determines that it is in an operation state when the determination flag FL is set to on, and determines that it is in a non-operation state when the determination flag FL is set to off.

[0076] When the operation amount detected by the operation amount detection device 150 becomes equal to or greater than the first operation amount threshold R1 while the determination flag FL is set to OFF, the operation state determination unit 112 switches the determination flag FL from OFF to ON (F=1). The first operation amount threshold R1 corresponds to the operation amount when the work is started, and is stored in the ROM 102 in advance. The first operation amount threshold R1 corresponds to, for example, about 10% of the operation amount when the maximum operation amount is 100%. In this embodiment, the operation device 50 includes an accelerator operation device 56, an arm operation device 52, and a bucket operation device 53. Therefore, the operation state determination unit 112 sets the determination flag FL to ON when any one of the accelerator operation amount, the arm operation amount, and the bucket operation amount detected by the operation amount detection device 150 becomes equal to or greater than the first operation amount threshold R1.

[0077] When the judgment flag FL is set to ON, the operation state judgment unit 112 switches the judgment flag FL from ON to OFF (F=0) when the operation amount detected by the operation amount detection device 150 becomes equal to or less than the second operation amount threshold R2. The second operation amount threshold R2 corresponds to the operation amount when the work is completed, and is stored in the ROM 102 in advance. The second operation amount threshold R2 is a value smaller than the first operation amount threshold R1, and corresponds to, for example, about 5% of the operation amount when the maximum operation amount is 100%. In this embodiment, the operation device 50 includes an accelerator operation device 56, an arm operation device 52, and a bucket operation device 53. Therefore, the operation state judgment unit 112 sets the judgment flag FL to OFF when any of the accelerator operation amount, the arm operation amount, and the bucket operation amount detected by the operation amount detection device 150 becomes equal to or less than the second operation amount threshold R2.

[0078] The correction value calculation unit 113 calculates the rotation speed deviation N Δ Based on this, the rotation speed correction value N C Calculate the following. N C =K I ×∫N Δ ×dt ···(2) In equation (2), K I is the integral gain, and dt is the control period of the main controller 100. Δ is calculated by the deviation calculation unit 111. In this way, the correction value calculation unit 113 calculates the rotation speed deviation N Δ The time integral value of (∫N Δ ×dt) and calculate the time integral (∫N Δ ×dt) with integral gain K I The rotation speed correction value N is obtained by multiplying C Calculate the integral gain K I is stored in advance in the ROM 102.

[0079] Figure 7 shows the relationship between engine load and rotation speed deviation N Δ7 is a diagram showing an example of a correlation map showing the relationship between the engine load and the rotation speed deviation N. As shown in Fig. 7, the characteristics of the wheel loader 1 shown in this correlation map are determined in advance by calculation or experiment. As shown in the correlation map, in the wheel loader 1, during idling, the engine load is the minimum load, the rotation speed deviation N Δ is the minimum deviation N Δmin As the engine load increases, the rotation speed deviation N Δ increases.

[0080] In the characteristics shown in the correlation map in Fig. 7, the larger the slope, the greater the rotation speed deviation N Δ Therefore, the larger the slope of the characteristic, the larger the integral gain K I By setting the rotation speed correction value N C As a result, after the wheel loader 1 starts working (after operation starts), the rotation speed deviation N Δ This reduces the integral gain K and allows you to quickly obtain the desired engine power. I The value of is determined in advance based on calculation or experiment.

[0081] When the determination flag FL is set to ON, that is, when the operation state determination unit 112 determines that the operation state is being performed, the correction value calculation unit 113 shown in FIG. 5 calculates the value calculated by the above-mentioned formula (2) as the rotation speed correction value N C When the determination flag FL is set to OFF, that is, when the operation state determination unit 112 determines that the touch panel is in a non-operation state, the correction value calculation unit 113 determines the time integral value (∫N Δ × dt) to the initial value (0 in this embodiment), C is set to a predetermined value (0 in this embodiment). In other words, the correction value calculation unit 113 sets the rotation speed deviation N Δ The time integral value of (∫N Δ × dt) based on the rotation speed correction value N C Calculate the following.

[0082] As shown in FIG. 5, the command value calculation unit 114 calculates a target engine rotation speed N E_T and the rotation speed correction value N C Using the above, the rotation speed command value N E_C Calculate the following. N E_C =N E_T +N C (3) Target engine speed N E_T is calculated by the target speed calculation unit 110, and the rotation speed correction value N C is calculated by the correction value calculation unit 113. In this way, the command value calculation unit 114 receives the rotation speed correction value N C The target engine speed N E_T The rotation speed command value N E_C is output as an engine speed command to the engine controller 120. The engine controller 120 receives the rotation speed command value N E_C The engine 20 is controlled based on the above.

[0083] When the determination flag FL is set to OFF, that is, when the operation state determination unit 112 determines that the operation is not in progress, the correction value calculation unit 113 calculates the rotation speed correction value N C In other words, when it is determined that the operation is not being performed, the command value calculation unit 114 sets the rotation speed correction value N C Target engine speed N E_T No correction is made.

[0084] Hereinafter, engine control executed by the main controller 100 will be described with reference to Fig. 8A and Fig. 8B. Fig. 8A is a flowchart of engine control executed by the main controller 100. Fig. 8B is a flowchart of a process for setting a determination flag FL shown in the flowchart of Fig. 8A. The process shown in the flowchart of Fig. 8A is started, for example, when an ignition switch (engine key switch) is turned on, and after an initial setting (not shown) is performed, the process is repeatedly executed at a predetermined control period. In the initial setting, the determination flag FL is set to off.

[0085] In step S110, the target speed calculation unit 110 calculates the target engine rotation speed N E_T Then, the process proceeds to step S115.

[0086] In step S115, the deviation calculation unit 111 calculates the target engine rotation speed N E_T and the actual engine speed N detected by the engine speed sensor 64 E_A Based on the rotation speed deviation N Δ (see equation (1)), and the process proceeds to step S120.

[0087] In step S120, the operation state determination unit 112 executes a process of setting a determination flag FL. The operation state determination unit 112 sets the determination flag FL to ON or OFF based on the amount of operation detected by the operation amount detection device 150. The process of setting the determination flag FL will be described in detail with reference to Fig. 8B.

[0088] 8B, in step S121, the operation state determination unit 112 determines whether or not the currently set determination flag FL is on. If the currently set determination flag FL is off, the process proceeds to step S123, and if the currently set determination flag FL is on, the process proceeds to step S127.

[0089] In step S123, the operation state determination unit 112 determines whether or not any of the operation amounts of the multiple operation devices 50 is equal to or greater than the first operation amount threshold R1. If it is determined in step S123 that any of the operation amounts of the multiple operation devices 50 is equal to or greater than the first operation amount threshold R1, the process proceeds to step S125. If it is determined in step S123 that all of the operation amounts of the multiple operation devices 50 are less than the first operation amount threshold R1, the process proceeds to step S130 in FIG. 8A.

[0090] In step S127, the operation state determination unit 112 determines whether or not all of the operation amounts of the multiple operation devices 50 are equal to or less than the second operation amount threshold R2. If it is determined in step S127 that all of the operation amounts of the multiple operation devices 50 are equal to or less than the second operation amount threshold R2, the process proceeds to step S129. If it is determined in step S127 that any of the operation amounts of the multiple operation devices 50 is greater than the second operation amount threshold R2, the process proceeds to step S130 in FIG. 8A.

[0091] 8A, in step S130, the operation state determination unit 112 determines whether the state is an operation state or a non-operation state based on the determination flag FL set in step S120. If the determination flag FL is set to on, the operation state determination unit 112 determines that the state is an operation state, and proceeds to step S140. If the determination flag FL is set to off, the operation state determination unit 112 determines that the state is a non-operation state, and proceeds to step S150.

[0092] In step S140, the correction value calculation unit 113 calculates the rotation speed deviation N Δ The time integral value of is calculated, and the rotation speed correction value N is calculated based on the calculated time integral value. C (see equation (2)), and the process proceeds to step S160.

[0093] In step S150, the correction value calculation unit 113 calculates the rotation speed correction value N C This reset process resets the rotation speed deviation N ΔSince the time integral value of is set to the initial value (0 in this embodiment), the rotation speed correction value N C is set to a predetermined value (0 in this embodiment). When the reset process (step S150) is completed, the process proceeds to step S160.

[0094] In step S160, the command value calculation unit 114 calculates the target engine rotation speed N E_T The rotation speed correction value N calculated in step S140 or step S150 C By adding E_C (See equation (3)).

[0095] When the process of step S160 is completed, the process of the flowchart shown in FIG. 8A in this control cycle is terminated, and in the next control cycle, the process of steps S110 to S160 is executed again.

[0096] Hereinafter, the main operations and effects of the wheel loader 1 according to this embodiment will be described with reference to Fig. 9. Fig. 9 shows the parameters (accelerator operation amount R A , work operation amount R I , rotation speed command value N E_C , actual engine speed N E_A , engine power P E ) is a diagram showing a time series change in the rotational speed correction value N C Target engine speed N E_T The following description will be made in comparison with a comparative example in which correction is not performed. Note that the wheel loader 1 according to this embodiment and the wheel loader according to the comparative example of this embodiment are assumed to have the same operating procedures and amounts of operation for the various operating devices by the operator.

[0097] In Fig. 9, the time series changes of each parameter in this embodiment are indicated by solid lines, and the time series changes of each parameter in the comparative example are indicated by dashed lines. The horizontal axis in Fig. 9(a) to (e) indicates time (elapsed time). The vertical axis in Fig. 9(a) indicates the accelerator operation amount R A 9(b) represents the work operation amount R I 9(c) represents the rotation speed command value N E_C 9(d) represents the actual engine speed N E_A 9(e) is the engine power P E Shows.

[0098] In Fig. 9, time t0 is the time when the operator operates the accelerator operation device 56 and the vehicle body 8 begins to move forward. In other words, time t0 is the time when the determination flag FL is switched from off to on. Time t1 is the time when the operator operates the work operation devices (arm operation device 52 and bucket operation device 53) and begins to scoop up earth and sand with the arm 2 and bucket 3 while moving the vehicle body 8 forward. Time t2 is the time when the operator stops operating the accelerator operation device 56 and the work operation devices (arm operation device 52 and bucket operation device 53) to finish scooping up the earth and sand, and the vehicle body 8, arm 2, and bucket 3 begin to stop.

[0099] As shown in FIG. 9(a), the accelerator operation amount R A is small until time t0. This is because the operator has not operated the accelerator operation device 56 and the wheel loader 1 is stopped until time t0. At time t0, the vehicle body 8 starts traveling forward, and the accelerator operation amount R A In addition, since the bucket 3 needs to continue penetrating into the excavation target 91 during excavation, the accelerator operation amount R A remains large. After that, the excavation work ends at time t2, so the accelerator operation amount R Adecreases sharply.

[0100] As shown in FIG. 9(b), the work operation amount R I is small until time t1. Until time t1, the wheel loader 1 does not penetrate into the excavation target 91. From time t1, the operation of the work operation device (arm operation device 52 and bucket operation device 53) for lifting the arm 2 and scooping soil into the bucket 3 is started, and the work operation amount R I Then, at time t2, the excavation work ends, and the work operation amount R I decreases sharply.

[0101] As shown in FIG. 9(c), in the comparative example, the accelerator operation amount R A In response to the sudden increase in E_C Low rotation speed N L From medium rotation speed N M After that, the work operation amount R I In response to the sudden increase in E_C Medium rotation speed N M From high rotation speed N H has increased to.

[0102] In contrast, in the case of this embodiment, the accelerator operation amount R A In response to the sudden increase in E_C Low rotation speed N L From medium rotation speed N M Then, at medium rotation speeds N M This is because at time t0, the determination flag FL is switched from off to on, and the rotation speed correction value N C is the target engine speed N E_T This is added to the rotation speed command value N E_C This is because the work operation amount R from time t1 is calculated. I In response to the sudden increase in E_C Medium rotation speed N M From high rotation speed N H Then, at high rotation speeds NH In this case, the judgment flag FL remains on, and the rotation speed correction value N C is the target engine speed N E_T This is added to the rotation speed command value N E_C This is because the following is calculated:

[0103] As shown in FIG. 9(d), in the comparative example, the actual engine rotation speed N E_A is the rotation speed command value N from time t0 E_C It increases with the increase in the actual engine speed N E_A is the low rotation speed N L From medium rotation speed N M It increases rapidly up to a value slightly lower than N M This is because, as mentioned above, the rotation speed command value N E_C (= Target engine speed N E_T ) increases with the rotation speed deviation N Δ As a result, the fuel injection amount increases and the actual engine speed N E_A Medium rotation speed N M This is because a slightly lower value was in balance with the engine load.

[0104] The engine controller 120 executes integral control of the fuel injection amount. Therefore, as the fuel injection amount gradually increases, the actual engine rotation speed N E_A Medium rotation speed N M From time t1 to time t2, the rotation speed command value N E_C As the actual engine speed N increases E_A shows similar behavior.

[0105] In contrast, as shown in FIG. 9(d), in the present embodiment, the actual engine speed N E_A is the rotation speed command value N from time t0 E_C Following the increase in M This is because the rotation speed command value N E_C Medium rotation speed N MThe actual engine speed N E_A This is because the main controller 100 absorbs the rotation speed deviation immediately after the rotation speed correction value N C The rotation speed correction value N C This reduces the actual engine speed N E_A is medium rotation speed N M From time t1 to time t2, the rotation speed command value N E_C As the actual engine speed N increases E_A shows similar behavior.

[0106] As shown in FIG. 9(e), in the comparative example, the engine power P E is the actual engine speed N from time t0 E_A As the increase in L In the comparative example, the actual engine speed N E_A Medium rotation speed N M Because it is lower, the engine power P E is the desired power, P M After that, the actual engine speed N E_A Medium rotation speed N M As the engine power P E Medium power P M However, by the time t1, which is the next operation timing, the rotation speed deviation N Δ As a result, in the comparative example, the desired engine power is not obtained by time t2. From time t1 to time t2, the engine power P E shows similar behavior, and the desired engine power cannot be obtained.

[0107] In contrast, as shown in FIG. 9(e), in the present embodiment, the actual engine speed N E_AAs the engine power P E Low power P L From the desired power, the medium power P M This is because the actual engine speed N E_A Rapidly rotates at medium speed N M After that, from time t1 to time t2, the engine power P E shows similar behavior, and the desired engine power can be obtained.

[0108] As described above, in the case of excavation work in which the vehicle body 8 travels forward and the working implement 6 operates, in the comparative example, the actual engine rotation speed N E_A is the rotation speed command value N E_C Since the condition lower than the engine power P E does not meet the engine power required for work (i.e., the desired power), and the work efficiency decreases.

[0109] In contrast, in this embodiment, the main controller 100 detects the rotation speed deviation N Δ The rotation speed correction value N is set to cancel out C Target engine speed N E_T Rotation speed command value N added to E_C to the engine controller 120. As a result, after the operation for performing the work is started, the engine power P E The engine power quickly rises to the engine power required for work (that is, the desired power). As a result, in this embodiment, the efficiency of work performed by the wheel loader 1 can be improved compared to the comparative example.

[0110] The configuration, operation, and effects of the embodiment of the present invention configured as described above can be summarized as follows.

[0111] (1) A wheel loader (working machine) 1 according to this embodiment includes a vehicle body 8, an engine 20 mounted on the vehicle body 8, a traveling drive device 45 that drives wheels 7 provided on the vehicle body 8, a hydraulic pump 30A driven by the engine 20, hydraulic cylinders (arm cylinder 4 and bucket cylinder 5) that are extended and retracted by hydraulic oil discharged from the hydraulic pump 30A, a work device 6 having a driven member (arm 2 and bucket 3) that is moved in accordance with the extension and retraction of the hydraulic cylinders (arm cylinder 4 and bucket cylinder 5), an operation device 50 that operates at least one of the traveling drive device 45 and the work device 6, an operation amount detection device 150 that detects the amount of operation of the operation device 50, and an actual rotation speed N E_A and a control device (a main controller 100 and an engine controller 120) that controls the engine 20.

[0112] The main controller 100 determines the target rotation speed N of the engine 20 based on the detection result of the operation amount detection device 150. E_T The main controller 100 calculates the calculated target rotation speed N E_T and the actual rotation speed N of the engine 20 detected by the engine rotation speed sensor 64. E_A The rotation speed deviation N Δ The time integral value of (∫N Δ ×dt). The main controller 100 calculates the calculated time integral value (∫N Δ × dt) based on the rotation speed correction value N C The main controller 100 calculates the calculated rotation speed correction value N C and the target rotation speed N of the engine 20 E_T The rotation speed command value N E_C The main controller 100 calculates the rotation speed command value N E_CBased on the detection result of the operation amount detection device 150, the main controller 100 determines whether the operation device 50 (any of the accelerator operation device 56, the arm operation device 52, and the bucket operation device 53) is in an operation state in which it is being operated, or whether the operation devices 50 (all of the accelerator operation device 56, the arm operation device 52, and the bucket operation device 53) are in a non-operation state in which they are not being operated. If it is determined that the operation devices 50 are in a non-operation state, the main controller 100 calculates the time integral value (∫N Δ ×dt) to a predetermined initial value (0 in this embodiment) and controls the engine 20. That is, the main controller 100 sets the time integral value (∫N Δ × dt) and initialize the rotation speed correction value N C is set to a predetermined value (0 in this embodiment) to control the engine 20.

[0113] Therefore, for example, when an operator starts to perform a task, the rotation speed deviation N Δ The time integral value of (∫N Δ ×dt) is calculated, and the calculated time integral (∫N Δ × dt) based on the rotation speed correction value N C is calculated, and the rotation speed correction value N C The target rotation speed N of the engine 20 is E_T is corrected.

[0114] By this correction, the main controller 100 detects the rotation speed deviation N Δ The rotation speed command value N E_C is output to the engine controller 120. As a result, after the operation for performing the work is started, the engine power P E The engine power quickly rises to the engine power required for the work (i.e., the desired power). In this way, in this embodiment, the operator is not required to adjust the correction characteristics, and the desired engine power can be quickly obtained without requiring the operator to do any work and without wasting fuel.

[0115] (2) In addition, the engine controller 120 executes integral control of the fuel injection amount so that the fuel injection amount is gradually increased. As the engine controller 120 gradually increases the fuel injection amount by the integral control of the fuel injection amount, the main controller 100 adjusts the rotation speed correction value N C The rotation speed correction value N C This reduces the actual engine speed N E_A is the target engine speed N E_T As a result, it is possible to prevent the generation of unnecessary engine power and an excessive increase in the engine load, thereby preventing wasteful fuel consumption.

[0116] (3) The wheel loader 1 is equipped with a generator motor (generator) 40 that generates electricity using the power of the engine 20. The traveling drive device 45 is equipped with a traveling motor (electric motor) 43 that is driven by the electric power generated by the generator motor 40 and operates the wheels 7.

[0117] In this embodiment, the actual rotation speed N E_A The rotation speed of the engine 20 and the traveling motor 43 are not linked and are controlled separately. E The power obtained by subtracting the power supplied to the working device 6 and the traveling device 11 from the above is consumed by the shaft of the engine 20, and the actual engine speed N E_A Therefore, in the above-mentioned comparative example, when the desired engine power is not reached, the actual engine rotation speed N E_A The engine power that should be consumed to maintain or increase the actual engine speed N E_A In contrast, in this embodiment, the rotation speed deviation N Δ The rotation speed correction value N is based on the time integral value of C Calculate the rotation speed correction value N C The target rotation speed N of the engine 20 is E_T Therefore, the actual rotation speed N of the engine 20 is corrected. E_AIn a configuration in which the rotational speed of the engine 11 and the rotational speed of the traveling motor 43 that drives the traveling device 11 are controlled independently, a shortage of engine power can be prevented, thereby effectively suppressing a decrease in work efficiency.

[0118] (4) When it is determined that the main controller 100 is in a non-operation state, the main controller 100 calculates the rotation speed correction value N C is set to 0 (No in S130 in FIG. 8A → S150). As a result, when no work is being performed, such as during idling, the target engine rotation speed N based on the rotation speed deviation NΔ (minimum deviation NΔmin) is set to 0 (No in S130 in FIG. 8A → S150). E_T As a result, unnecessary fuel consumption can be prevented.

[0119] <Second embodiment> A wheel loader 1 according to the second embodiment will be described. Note that the same reference numbers are used for the same or corresponding parts as those in the first embodiment, and differences will be mainly described. In the second embodiment, the rotation speed correction value N C The calculation method is different from that in the first embodiment.

[0120] Specifically, the correction value calculation unit 113 calculates the rotation speed deviation N Δ Based on this, the rotation speed correction value N C Calculate the following. N C =K P ×N Δ +K I ×∫N Δ ×dt ···(4) Here, K P is the proportional gain, and K I is the integral gain, and dt is the control period of the main controller 100.

[0121] The main controller 100 according to the second embodiment controls the target rotation speed N E_T and the actual rotation speed N of the engine 20 E_A The rotation speed deviation N Δ The time integral value of (∫NΔ ×dt) with integral gain K I Multiplied by (K I ×∫N Δ ×dt) and the target rotation speed N of the engine 20 E_T and the actual rotation speed N of the engine 20 E_A The rotation speed deviation N Δ Proportional gain K P Multiplied by (K P ×N Δ ) to obtain the rotation speed correction value N C Calculate the proportional gain K P and integral gain K I is stored in advance in the ROM 102.

[0122] In this manner, in this embodiment, the main controller 100 controls the rotation speed correction value N C This calculates the actual engine speed N E_A Target engine speed N is greater than E_T is set, the actual engine speed N E_A Target engine speed N E_T Increase the rotation speed deviation to N Δ can be reduced.

[0123] <Third embodiment> A wheel loader 1 according to the third embodiment will be described. Note that the same reference numerals are used for the same or corresponding parts as those in the first embodiment, and differences will be mainly described. In the third embodiment, the rotation speed correction value N C The calculation method is different from that in the first embodiment.

[0124] Specifically, the correction value calculation unit 113 calculates the rotation speed deviation N Δ Based on this, the rotation speed correction value N C Calculate the following. N C =K P ×N Δ +K I ×∫NΔ ×dt+K D ×dN Δ / dt ···(5) Here, K P is the proportional gain, and K I is the integral gain, and K D is the differential gain, and dt is the control period of the main controller 100.

[0125] The main controller 100 according to the third embodiment controls the target rotation speed N E_T and the actual rotation speed N of the engine 20 E_A The rotation speed deviation N Δ The time integral value of (∫N Δ ×dt) with integral gain K I Multiplied by (K I ×∫N Δ ×dt) and the target rotation speed N of the engine 20 E_T and the actual rotation speed N of the engine 20 E_A The rotation speed deviation N Δ Proportional gain K P Multiplied by (K P ×N Δ ) and the target rotation speed N of the engine 20 E_T and the actual rotation speed N of the engine 20 E_A The rotation speed deviation N Δ The time derivative of (dN Δ / dt) with differential gain K D Multiplied by (K D ×dN Δ / dt) to obtain the rotation speed correction value N C Calculate the proportional gain K P , integral gain K I and differential gain K D is stored in advance in the ROM 102.

[0126] In this manner, in this embodiment, the main controller 100 calculates the rotation speed correction value N C This calculates the actual engine speed N E_A Target engine speed N is greater than E_Tis set, the actual engine speed N E_A Target engine speed N E_T Increase the rotation speed deviation to N Δ In addition, since the third embodiment is a control in which D control is added to the PI control of the second embodiment, the rotation speed deviation N Δ From the occurrence of the steady state (actual engine speed N E_A is the target engine speed N E_T As a result, according to the third embodiment, the desired engine power P is reached more quickly than in the first and second embodiments. E can be obtained.

[0127] As described above, the wheel loaders 1 according to the first to third embodiments have been described, but the following modifications are also within the scope of the present invention.

[0128] <Variation 1> In the first embodiment, the main controller 100 calculates the rotation speed correction value N C In the second embodiment, the main controller 100 calculates the rotation speed correction value N C In the third embodiment, the main controller 100 calculates the rotation speed correction value N C The main controller 100 calculates the rotation speed correction value N C may be calculated.

[0129] In this case, the correction value calculation unit 113 shown in FIG. 5 calculates the rotation speed deviation N Δ Based on this, the rotation speed correction value N C Calculate the following. N C =K I ×∫N Δ ×dt+K D×dN Δ / dt ···(6) Here, K I is the integral gain, and K D is the differential gain, and dt is the control period of the main controller 100.

[0130] The main controller 100 according to the first modification sets the target rotation speed N E_T and the actual rotation speed N of the engine 20 E_A The rotation speed deviation N Δ The time integral value of (∫N Δ ×dt) with integral gain K I Multiplied by (K I ×∫N Δ ×dt) and the target rotation speed N of the engine 20 E_T and the actual rotation speed N of the engine 20 E_A The rotation speed deviation N Δ The time derivative of (dN Δ / dt) with differential gain K D Multiplied by (K D ×dN Δ / dt) to obtain the rotation speed correction value N C Calculate the following.

[0131] In this manner, in this embodiment, the main controller 100 controls the rotation speed correction value N C This calculates the actual engine speed N E_A Target engine speed N is greater than E_T is set, the actual engine speed N E_A Target engine speed N E_T Increase the rotation speed deviation to N Δ can be reduced.

[0132] <Variation 2> In the above embodiment, the main controller 100 determines whether the state is an operation state or a non-operation state based on the detection result of the operation amount detection device 150, and when it is determined that the state is a non-operation state, the rotation speed deviation N ΔAlthough an example has been described in which the time integral value of is set to the initial value, the present invention is not limited to this.

[0133] The main controller 100 determines whether or not the state has been switched from a non-operated state to an operated state based on the detection result of the operation amount detection device 150, and when it is determined that the state has been switched from a non-operated state to an operated state, the main controller 100 determines whether or not the state has been switched from a non-operated state to an operated state. Δ The engine 20 may be controlled by setting the time integral value of the above to an initial value.

[0134] With reference to FIG. 10, engine control executed by the main controller 100 according to this modification will be described. FIG. 10 is a diagram similar to FIG. 8A, and is a flowchart of engine control executed by the main controller 100. The main controller 100 according to this modification executes the process of step S230 instead of the process of step S130 in the flowchart of FIG. 8A. Moreover, the main controller 100 executes the processes of steps S245, S260, and S265 instead of the process of step S160 in the flowchart of FIG. 8A. Note that the same processes as those shown in the flowchart of FIG. 8A are denoted by the same reference numerals, and hereinafter, the parts different from the processes shown in the flowchart of FIG. 8A will be mainly described.

[0135] 10, when the main controller 100 completes the determination flag setting process (step S120), the process proceeds to step S230, where the main controller 100 determines whether or not the non-operated state has been switched to the operated state. For example, when the determination flag FL set in step S120 of the previous control cycle is off and the determination flag FL set in step S120 of the current control cycle is on, the main controller 100 determines that the non-operated state has been switched to the operated state, and proceeds to step S150. In other cases, the main controller 100 determines that the non-operated state has not been switched to the operated state, and proceeds to step S140.

[0136] In step S150, the main controller 100 executes the same process as in the above embodiment, and then proceeds to step S140. In step S140, the main controller 100 executes the same process as in the above embodiment, and then proceeds to step S245. In step S245, the main controller 100 executes the same process as in step S130 described in the above embodiment. In step S245, the main controller 100 determines whether it is in an operating state or a non-operating state based on the determination flag FL set in step S120. If the determination flag FL is set to on, the main controller 100 determines that it is in an operating state, and proceeds to step S260. If the determination flag FL is set to off, the main controller 100 determines that it is in a non-operating state, and proceeds to step S265.

[0137] In step S260, the main controller 100 calculates the target engine speed N E_T The rotation speed correction value N calculated in step S140 C Specifically, the command value calculation unit 114 corrects the target engine rotation speed N E_T Rotation speed correction value N C By adding the above, the rotation speed command value N E_C When the process of step S260 is completed, the process of the flowchart shown in Fig. 10 for this control cycle ends.

[0138] In step S265, the main controller 100 calculates the target engine rotation speed N E_T Without correcting, the rotation speed command value N E_C When the process of step S265 is completed, the process of the flowchart shown in Fig. 10 for this control cycle ends.

[0139] According to this modification, the same effects as those of the above embodiment can be achieved. Note that when the determination flag FL is switched from OFF to ON, the main controller 100Δ The time integral value of is set as the initial value, and the rotation speed correction value N C is reset to a predetermined value. As a result, immediately after the determination flag FL is switched from off to on, the rotation speed correction value N C The actual engine speed N E_A This can prevent the behavior of the device from becoming unstable.

[0140] <Variation 3> In the above embodiment, an example was described in which the judgment flag FL is set to on when the operation amount detected by the operation amount detection device 150 becomes equal to or greater than the first operation amount threshold R1, and the judgment flag FL is set to off when the operation amount detected by the operation amount detection device 150 becomes equal to or less than the second operation amount threshold R2, but the present invention is not limited to this.

[0141] The main controller 100 may determine that the operation state is present when the state in which the operation amount detected by the operation amount detection device 150 is equal to or greater than a predetermined first operation amount threshold R1 continues for a predetermined first time T1, and may determine that the non-operation state is present when the state in which the operation amount detected by the operation amount detection device 150 is equal to or less than a predetermined second operation amount threshold R2 continues for a predetermined second time T2. As described above, the second operation amount threshold R2 is smaller than the first operation amount threshold R1.

[0142] With reference to FIG. 11, the process of setting the determination flag FL by the main controller 100 according to this modified example will be described. FIG. 11 is a diagram similar to FIG. 8B, and is a flowchart of the process of setting the determination flag executed by the main controller 100 according to this modified example. As shown in FIG. 11, in the process of setting the determination flag (step S120 in FIG. 8A), the main controller 100 according to this modified example first executes the process of step S121. In step S121, the main controller 100 judges whether or not the currently set determination flag FL is on. If the currently set determination flag FL is off, the process proceeds to step S323, and if the currently set determination flag FL is on, the process proceeds to step S327.

[0143] In step S323, when any of the accelerator operation amount, the arm operation amount, and the bucket operation amount detected by the operation amount detection device 150 becomes equal to or greater than the first operation amount threshold R1, the main controller 100 starts measuring the time from that point. The main controller 100 judges whether or not the state in which any of the accelerator operation amount, the arm operation amount, and the bucket operation amount detected by the operation amount detection device 150 is equal to or greater than the first operation amount threshold R1 has continued for the first time T1. In step S323, if it is judged that the state in which any of the operation amounts of the multiple operation devices 50 is equal to or greater than the first operation amount threshold R1 has continued for the first time T1, the process proceeds to step S125, and otherwise the process proceeds to step S130 in FIG. 8A. The first time T1 is stored in advance in the ROM 102.

[0144] In step S327, when the accelerator operation amount, the arm operation amount, and the bucket operation amount detected by the operation amount detection device 150 are all equal to or less than the second operation amount threshold R2, the main controller 100 starts measuring the time from that point. The main controller 100 judges whether or not the state in which the accelerator operation amount, the arm operation amount, and the bucket operation amount detected by the operation amount detection device 150 are all equal to or less than the second operation amount threshold R2 has continued for the second time T2. In step S327, if it is judged that the state in which all of the operation amounts of the multiple operation devices 50 are all equal to or less than the second operation amount threshold R2 has continued for the second time T2, the process proceeds to step S129, and otherwise the process proceeds to step S130 in FIG. 8A. The second time T2 is stored in advance in the ROM 102.

[0145] Steps S125 and S129 in FIG. 11 are similar to steps S125 and S129 in FIG. 8B, and therefore description thereof will be omitted.

[0146] In this modified example, the determination flag FL is not switched immediately when the operation amount detected by the operation amount detection device 150 becomes equal to or greater than the operation amount threshold or equal to or less than the operation amount threshold, but rather the determination flag FL is switched if the state continues for a predetermined time after the operation amount becomes equal to or greater than the operation amount threshold. As a result, if the accelerator pedal of the accelerator operation device 56 or the operation levers of the arm operation device 52 and the bucket operation device 53 are operated for a short time while not working, or if the operation of the accelerator pedal of the accelerator operation device 56 or the operation levers of the arm operation device 52 and the bucket operation device 53 is interrupted for a short time while working, the determination flag FL maintains its current state. For this reason, according to this modified example, the wheel loader 1 can be operated stably.

[0147] <Variation 4> In the above embodiment, an example has been described in which a single traveling motor 43 that supplies power to the traveling device 11 is mounted on the wheel loader 1, but the present invention is not limited to this. The present invention may be applied to a wheel loader 1 equipped with a plurality of traveling motors 43. For example, the present invention can be applied to a wheel loader 1 equipped with a traveling motor 43 that drives the left front wheel 7A and a traveling motor 43 that drives the right front wheel 7A. Furthermore, the present invention can also be applied to a wheel loader 1 equipped with four traveling motors 43 that drive each of a pair of left and right front wheels 7A and a pair of left and right rear wheels 7B. The traveling motor 43 may be connected to the wheels 7 via a transmission, or may be configured to be integrated with the wheels 7.

[0148] <Variation 5> In the above embodiment, an example has been described in which the working machine is an electrically driven wheel loader, but the present invention is not limited thereto. For example, the present invention may be applied to a torque converter driven wheel loader, or a hydraulic static transmission (HST) driven wheel loader in which the power of the engine 20 is converted into hydraulic power and transmitted to the wheels 7. In a torque converter driven wheel loader, the wheels 7 are driven according to the actual rotation speed of the engine 20, so that the actual rotation speed of the engine 20 is unlikely to decrease. In contrast, an HST driven wheel loader is configured such that the actual rotation speed of the engine 20 and the rotation speed of the hydraulic motor are controlled independently. For this reason, as with the electrically driven wheel loader described in the above embodiment, a decrease in the actual rotation speed of the engine 20 due to an increase in the load on the engine 20 is likely to occur. For this reason, by applying the present invention, as with the above embodiment, a particularly high effect can be obtained.

[0149] <Variation 6> Target engine speed N E_T The calculation method is not limited to the method described in the above embodiment.

[0150] <Modification 6-1> For example, instead of the maximum value selection unit 125, a calculation unit may be provided that calculates the sum of the required power of the hydraulic pump 30A, the required power of the hydraulic pump 30B, and the required power of the hydraulic pump 30C.

[0151] <Modification 6-2> The main controller 100 controls the operation amounts of the arm operation device 52, the bucket operation device 53, and the accelerator operation device 56, and the target engine rotation speed N E_T Based on a table that defines the relationship between the target engine speed N E_T In this case, the main controller 100 may calculate the arm operation amount and the target engine rotation speed N E_T The main controller 100 refers to a table that defines the relationship between the bucket operation amount and the target engine rotation speed N E_T The main controller 100 refers to a table that defines the relationship between the accelerator operation amount and the target engine rotation speed N E_T The main controller 100 refers to a table that defines the relationship between the first target engine speed and the third target engine speed, and calculates a third target engine speed based on the amount of operation of the accelerator operation device 56. The main controller 100 selects the largest one of the first to third target engine speeds, and sets the selected target engine speed N E_T Rotation speed correction value N C The result is corrected by and output to the engine controller 120 as a rotation speed command.

[0152] <Modification 6-3> The main controller 100 calculates the sum of the operation amount of the arm operation device 52, the operation amount of the bucket operation device 53, and the operation amount of the accelerator operation device 56, and the target rotation speed N E_T Based on a table that defines the relationship between the target engine speed N E_T may be calculated.

[0153] <Variation 7> In the above embodiment, an example has been described in which the arm operation amount sensor 52a and the bucket operation amount sensor 53a are potentiometers, but the present invention is not limited to this. For example, the arm operation amount sensor 52a may be a pressure sensor that detects a pilot pressure input to a pilot chamber of a directional control valve for controlling the arm cylinder 4 that constitutes the front control unit 31. Similarly, the bucket operation amount sensor 53a may be a pressure sensor that detects a pilot pressure input to a pilot chamber of a directional control valve for controlling the bucket cylinder 5 that constitutes the front control unit 31.

[0154] Furthermore, an arm relative angle sensor 62 and a bucket relative angle sensor 63 may be employed as the operation amount detection device. For example, the main controller 100 determines that an operation state is present when the time rate of change of the arm relative angle detected by the arm relative angle sensor 62 is equal to or greater than a predetermined threshold. Furthermore, the main controller 100 determines that an operation state is present when the time rate of change of the bucket relative angle detected by the bucket relative angle sensor 63 is equal to or greater than a predetermined threshold.

[0155] Furthermore, a photographing device such as a camera may be used as the operation amount detection device. For example, the main controller 100 may monitor the movement of the operator using a photographing device that photographs the inside of the cab 12, and determine whether the state is operating or non-operating based on the movement of the operator. The main controller 100 may also monitor the movement of the working implement 6 and the wheels 7 using a photographing device that photographs the area in front of the wheel loader 1, and determine whether the state is operating or non-operating based on the movement of the working implement 6 and the wheels 7.

[0156] An infrared sensor may be adopted as the operation amount detection device. For example, the main controller 100 may determine whether the wheel loader 1 is in an operating state or a non-operating state based on information detected by an infrared sensor that monitors the front of the wheel loader 1. In this case, the main controller 100 determines that the wheel loader 1 is in an operating state when the distance between an object recognized by the infrared sensor and the wheel loader 1 is changing, and determines that the wheel loader 1 is in a non-operating state when the distance between an object recognized by the infrared sensor and the wheel loader 1 is not changing.

[0157] <Variation 8> In the above embodiment, the main controller 100 may perform moving average processing or low-pass filtering on the values ​​used in various judgments and calculations in order to avoid the influence of disturbances and noise. C By performing moving average processing or low-pass filter processing on the target engine rotation speed N E_T Immediately after the increase in the rotation speed correction value N C As a result, the stability and operability of the engine control can be improved.

[0158] <Variation 9> In the above embodiment, an example in which the initial value of the time integral value is 0 (zero) has been described, but the present invention is not limited to this. The initial value of the time integral value may be any numerical value other than 0 (zero). That is, in the reset process (step S150 in FIG. 8A), the rotation speed correction value N C is not limited to being set to 0 (zero), but may be set to a predetermined value other than 0 (zero).

[0159] <Modification 10> Some or all of the functions of the main controller 100 described in the above embodiment may be realized by hardware (for example, by designing the logic for executing each function as an integrated circuit).

[0160] <Modification 11> The engine controller 120 may have some or all of the functions of the main controller 100 described in the above embodiment, and the main controller 100 may have some or all of the functions of the engine controller 120 described in the above embodiment.

[0161] <Modification 12> In the above embodiment, an example has been described in which the process of setting the determination flag FL on / off is executed based on the accelerator operation amount, the arm operation amount, and the bucket operation amount detected by the operation amount detection device 150, but the present invention is not limited to this. The process of setting the determination flag FL on / off may be executed based on only one of the accelerator operation amount, the arm operation amount, and the bucket operation amount detected by the operation amount detection device 150.

[0162] <Modification 13> In the above embodiment, an example has been described in which the working machine is a wheel loader 1, but the present invention is not limited to this. The present invention can be applied to various working machines in which the traveling device or working device is driven by engine power, such as a forklift, a shovel, a lift truck, etc. For example, when performing excavation work with a shovel, loading work, or when traveling forward with the lift raised by a forklift, the target engine rotation speed N E_T and actual engine speed N E_A The target engine speed N based on the time integral of the difference E_T Correction may be performed.

[0163] Although the embodiments of the present invention have been described above, the above embodiments merely show some of the application examples of the present invention, and the technical scope of the present invention is not limited to the specific configurations of the above embodiments. The above-mentioned embodiments and modifications are exemplified to easily explain the present invention, and are not necessarily limited to those having all the configurations described. In addition, it is possible to replace a part of the configuration of a certain embodiment or modification with the configuration of another embodiment or modification, and it is also possible to add the configuration of another embodiment or modification to the configuration of a certain embodiment or modification. Note that the control lines and information lines shown in the figures show those that are considered necessary for explanation, and do not necessarily show all the control lines and information lines necessary on the product. In reality, it may be considered that almost all configurations are connected to each other. [Explanation of symbols]

[0164] 1...wheel loader (working machine), 2...arm (driven member), 3...bucket (driven member), 4...arm cylinder (hydraulic cylinder), 5...bucket cylinder (hydraulic cylinder), 6...working device, 7...wheel, 8...body, 11...traveling device, 12...operator's cab, 20...engine, 23...fuel injection device, 30A, 30B, 30C...hydraulic pump, 40...generator motor (generator), 43...traveling motor (electric motor), 45...traveling drive device, 50...operation device, 52...arm operation device, 52a...arm operation amount sensor, 53...bucket operation device, 53a...bucket bucket operation amount sensor, 56... accelerator operation device, 56a... accelerator operation amount sensor, 58... motor speed sensor, 62... arm relative angle sensor, 63... bucket relative angle sensor, 64... engine rotation speed sensor, 71... first discharge pressure sensor, 72... second discharge pressure sensor, 73... third discharge pressure sensor, 100... main controller (control device), 110... target speed calculation unit, 111... deviation calculation unit, 112... operation state determination unit, 113... correction value calculation unit, 114... command value calculation unit, 120... engine controller, 150... operation amount detection device, 151... discharge pressure detection device, C …Rotational speed correction value, N E_A …Actual engine speed (actual engine speed), N E_C …Rotation speed command value, N E_T… target engine speed (engine target speed), N Δ …Rotational speed deviation, P E …Engine power, R1…First operation amount threshold, R2…Second operation amount threshold, T1…First time, T2…Second time

Claims

1. The car body and An engine mounted on the vehicle body; A travel drive device that drives wheels provided on the vehicle body; a hydraulic pump driven by the engine; a working device including a hydraulic cylinder that is expanded and contracted by hydraulic oil discharged from the hydraulic pump, and a driven member that is moved in response to the expansion and contraction of the hydraulic cylinder; An operation device for operating at least one of the traveling drive device and the working device; an operation amount detection device for detecting an operation amount of the operation device; an engine rotation speed sensor for detecting an actual rotation speed of the engine; A control device for controlling the engine, The control device includes: calculating a target rotation speed of the engine based on a detection result of the operation amount detection device; Calculating a time integral value of a difference between the calculated target rotation speed of the engine and an actual rotation speed of the engine detected by the engine rotation speed sensor; Calculating a rotation speed correction value based on the calculated time integral value; calculating a rotation speed command value for the engine by adding the calculated rotation speed correction value and a target rotation speed of the engine; Controlling the engine based on the calculated rotation speed command value of the engine; determining whether the operation device is in an operation state in which it is being operated or in a non-operation state in which it is not being operated based on a detection result of the operation amount detection device; When it is determined that the non-operation state has been switched to the operation state, or when it is determined that the non-operation state is being maintained, the time integral value is set to a predetermined initial value and the engine is controlled. A working machine characterized by:

2. 2. The work machine according to claim 1, The control device includes: When it is determined that the non-operation state is present, the rotation speed correction value is set to 0. A working machine characterized by:

3. 2. The work machine according to claim 1, The control device includes: determining that the operation state is present when a state in which the operation amount detected by the operation amount detection device is equal to or greater than a predetermined first operation amount threshold continues for a predetermined first time period; determining that the non-operation state exists when a state in which the operation amount detected by the operation amount detection device is equal to or less than a predetermined second operation amount threshold continues for a predetermined second time period; The second operation amount threshold is smaller than the first operation amount threshold. A working machine characterized by:

4. 2. The work machine according to claim 1, The control device includes: The rotation speed correction value is calculated by adding a value obtained by multiplying the time integral value by an integral gain and a value obtained by multiplying a difference between the target rotation speed of the engine and the actual rotation speed of the engine by a proportional gain. A working machine characterized by:

5. 2. The work machine according to claim 1, The control device includes: The rotation speed correction value is calculated by adding together a value obtained by multiplying the time integral value by an integral gain, a value obtained by multiplying a difference between the target rotation speed of the engine and the actual rotation speed of the engine by a proportional gain, and a value obtained by multiplying a time derivative value of the difference between the target rotation speed of the engine and the actual rotation speed of the engine by a derivative gain. A working machine characterized by:

6. 2. The work machine according to claim 1, a generator that generates electricity using the power of the engine, The traveling drive device includes an electric motor that is driven by the electric power generated by the generator to operate the wheels. A working machine characterized by:

Images