Control system, control method, and work vehicle

Abstract

This control system is for controlling a fuel injection amount of a diesel engine mounted on a work vehicle, and comprises: an operation device for switching ON and OFF states of a limit mode for limiting the fuel injection amount; and a control device for changing control of the fuel injection amount in response to a change in a signal that is output from the operation device and indicates the ON or OFF state of the limit mode. The limit mode is a mode in which the fuel injection amount is limited so that the diesel engine generates smaller torque than the torque generated at the same engine rotational speed when the limit mode is in the OFF state.

Description

Control system, control method and work vehicle

[0001] The present disclosure relates to a control system, a control method, and a work vehicle for controlling a fuel injection amount of a diesel engine.

[0002] Various technologies have been developed to achieve energy-saving operation of mobile agricultural machinery or construction machinery (hereinafter referred to as "energy-saving operation"). Hereinafter, mobile agricultural machinery and construction machinery will be collectively referred to as "work vehicles."

[0003] Patent Document 1 describes a control system in which a rotation speed command value for reducing the engine rotation speed by a predetermined amount is input to an engine control unit in response to an operation command from a driver. When the engine rotation speed is reduced, a control for maintaining the vehicle speed is performed by a transmission, thereby realizing energy-saving driving while maintaining the vehicle speed.

[0004] Patent Document 2 describes a work vehicle that displays an energy-saving operation message on a display device when the engine speed is higher than a predetermined speed and the engine load rate is lower than a predetermined load rate. This technology prevents engine stalls that can occur when the engine speed is reduced under high engine load conditions. Furthermore, even if the engine speed is reduced while the PTO (Power Take Off) is in use, a speed increase command to increase the PTO shaft speed is displayed on the display to notify the user, and control is performed to maintain the PTO shaft speed. This achieves energy-saving operation while suppressing fluctuations in the PTO shaft speed.

[0005] JP 2012-162248 A JP 2016-84102 A

[0006] In the technology of Patent Document 1, lowering the engine speed also changes the PTO shaft speed, which may affect the work the user is doing. Also, in the technology of Patent Documents 1 and 2, the user must manually lower the engine speed, which can be time-consuming for the user if they have to do this operation multiple times.

[0007] Therefore, there is a demand for technology that can improve user convenience while facilitating energy-saving operation.

[0008] A control system according to one aspect of the present disclosure is a control system for controlling the fuel injection amount of a diesel engine mounted on a work vehicle, and includes an operating device for switching between the on / off state of a limit mode that limits the fuel injection amount, and a control device that changes the control of the fuel injection amount in response to a change in a signal output from the operating device that indicates the on / off state of the limit mode, wherein the limit mode is a mode that limits the fuel injection amount so as to generate a torque that is smaller than the torque generated by the diesel engine at the same engine speed when the limit mode is in the off state.

[0009] A work vehicle according to one aspect of the present disclosure includes a diesel engine and the above-described control system.

[0010] A control method according to one aspect of the present disclosure is a control method implemented in a computer to control the fuel injection amount of a diesel engine mounted on a work vehicle, which causes the computer to receive a signal indicating the on / off state of a limit mode that limits the fuel injection amount, and change the control of the fuel injection amount in response to a change in the signal, wherein the limit mode is a mode that limits the fuel injection amount so as to generate a torque that is smaller than the torque generated by the diesel engine at the same engine speed when the limit mode is off.

[0011] A general or specific aspect of the present disclosure may be realized by an apparatus, a system, a method, an integrated circuit, a computer program, or a computer-readable non-transitory storage medium, or any combination thereof. The computer-readable storage medium may include a volatile storage medium or a non-volatile storage medium. An apparatus may be composed of multiple devices. When an apparatus is composed of two or more devices, the two or more devices may be located in a single device or may be located separately in two or more separate devices.

[0012] According to the embodiments of the present disclosure, it is possible to facilitate energy-saving operation while improving user convenience.

[0013] FIG. 1 is a side view schematically showing an example of a work vehicle in an embodiment of the present disclosure. FIG. 2 is a diagram showing an example of a group of operation switches and an operation terminal provided inside a cabin equipped in the work vehicle. FIG. 3 is a block diagram showing an example of the hardware configuration of a control system. FIG. 4 is a block diagram showing an example of the hardware configuration of an electronic control unit in an embodiment of the present disclosure. FIG. 5 is a flowchart showing a procedure for controlling a fuel injection amount according to a first implementation example of a control method in an embodiment of the present disclosure. FIG. 6 is a graph illustrating time-series changes in engine speed and the amount of fluctuation in engine speed. FIG. 7 is a graph illustrating an example of the relationship between engine speed and fuel injection amount. FIG. 8 is a graph showing how the fuel injection amount is limited and changes over time by turning on / off the fuel injection amount limit. FIG. 9 is a schematic diagram showing an example of a display screen displaying a notification message notifying a user of the on / off state of the limit mode. FIG. 10 is a flowchart showing a procedure for controlling a fuel injection amount according to a second implementation example of a control method in an embodiment of the present disclosure.

[0014] Hereinafter, embodiments of the present disclosure will be described. However, more detailed descriptions than necessary may be omitted. For example, detailed descriptions of already well-known matters and redundant descriptions of substantially identical configurations may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. Note that the inventors provide the accompanying drawings and the following description to enable those skilled in the art to fully understand the present disclosure, and do not intend for them to limit the subject matter described in the claims. In the following description, components having the same or similar functions are designated by the same reference numerals.

[0015] The following embodiments are examples, and the technology of the present disclosure is not limited to the following embodiments. For example, the numerical values, shapes, materials, steps, the order of the steps, the layout of the display screen, and the like shown in the following embodiments are merely examples, and various modifications are possible as long as no technical contradiction occurs. Furthermore, one aspect can be combined with another aspect as long as no technical contradiction occurs.

[0016] 1 is a side view schematically illustrating an example of a work vehicle 200 according to an embodiment of the present disclosure. The illustrated work vehicle 200 is a tractor that tows an implement (replaceable work device) 300.

[0017] The work vehicle 200 shown in Fig. 1 includes a vehicle body 201, a prime mover (engine) 202, and a transmission 203. The vehicle body 201 is provided with a traveling device including wheels 204 with tires, and a cabin 205. The traveling device includes four wheels 204, axles that rotate the four wheels, and braking devices (brakes) that apply braking to each axle. The wheels 204 in this example include a pair of front wheels 204F and a pair of rear wheels 204R. One or both of the front wheels 204F and the rear wheels 204R may be replaced with a plurality of wheels (crawlers) equipped with tracks rather than wheels with tires.

[0018] Inside the cabin 205, there are provided the meter panel unit 100, a driver's seat 207, a steering wheel 220, and a group of operation switches (see FIG. 2).

[0019] The work vehicle 200 in FIG. 1 is equipped with multiple external sensors that sense the surroundings of the work vehicle 200. The external sensors may include various sensors such as multiple cameras 270, multiple obstacle sensors 295, and multiple LiDAR sensors 290. The cameras 270 may be installed, for example, on the front, rear, left, and right sides of the work vehicle 200. The cameras 270 capture images of the environment surrounding the work vehicle 200 and generate image data. The images acquired by the cameras 270 may be transmitted to a terminal device for remote monitoring, for example. The cameras 270 are installed as needed, and the number of cameras 270 is arbitrary. The LiDAR sensor 290 is an example of an external sensor that outputs sensor data indicating the distribution of objects located in the surrounding environment of the work vehicle 200. In the example of FIG. 1, two LiDAR sensors 290 are installed at the front and rear of the cabin 205. The LiDAR sensor 290 may also be installed in other positions (for example, the lower front part of the vehicle body 201). While the work vehicle 200 is traveling, each LiDAR sensor 290 repeatedly outputs sensor data indicating the distance and direction to each measurement point of an object present in the surrounding environment, or the three-dimensional coordinate values ​​of each measurement point. The number of LiDAR sensors 290 is not limited to two, and may be one, or three or more. In the example of FIG. 1 , multiple obstacle sensors 295 are provided at the front and rear of the cabin 205. The obstacle sensors 295 may also be located in other locations. The obstacle sensors 295 may include, for example, a laser scanner or an ultrasonic sonar.

[0020] Work vehicle 200 further includes GNSS unit 260. GNSS is a general term for satellite positioning systems such as GPS (Global Positioning System), QZSS (Quasi-Zenith Satellite System, e.g., Michibiki), GLONASS, Galileo, and BeiDou. GNSS unit 260 receives satellite signals (also referred to as GNSS signals) transmitted from multiple GNSS satellites and performs positioning based on the satellite signals. GNSS unit 260 is provided on top of cabin 205, but may be provided in another location.

[0021] In this embodiment, the prime mover 202 is a diesel engine. An electric motor may be used together with the diesel engine. The transmission 203 can change the propulsive force and travel speed of the work vehicle 200 by changing gears. The transmission 203 can also switch the work vehicle 200 between forward and reverse travel.

[0022] A coupling device 208 is provided at the rear of the vehicle body 201. The coupling device 208 includes, for example, a three-point support device (also called a "three-point link" or "three-point hitch"), a PTO axle, a universal joint, and a communication cable. The coupling device 208 allows the implement 300 to be attached to and detached from the work vehicle 200. The coupling device 208 can raise and lower the three-point link using, for example, a hydraulic device, thereby changing the position or posture of the implement 300. Power can also be transmitted from the work vehicle 200 to the implement 300 via the universal joint. In other words, power is supplied from the prime mover 202, which is a diesel engine, to the implement 300 via the coupling device 208. The work vehicle 200 can pull the implement 300 and cause the implement 300 to perform a predetermined task. The coupling device may be provided at the front of the vehicle body 201. In this case, the implement can be connected to the front of the work vehicle 200.

[0023] 1 is, for example, a sprayer that sprays a chemical onto crops, but the implement 300 is not limited to a sprayer. Any implement 300, such as a mower, a seeder, a spreader, a rake, a baler, a harvester, a plow, a harrow, or a rotary, can be connected to the work vehicle 200 and used.

[0024] It should be noted that the work vehicle 200 such as a tractor can be configured to travel by manual driving, automatic steering, or automatic driving.

[0025] FIG. 2 is a diagram showing an example of an operation switch group 191 and an operation terminal 192 provided inside a cabin 205 of a work vehicle 200.

[0026] Inside the cabin, an operation switch group 191 including a plurality of switches that can be operated by the user is arranged. The operation switch group 191 may include, for example, a switch for selecting a gear position of the main transmission or the auxiliary transmission, a switch for switching between an automatic driving mode and a manual driving mode, a switch for switching between forward and reverse, a switch for switching between four-wheel drive and two-wheel drive, a switch for disconnecting the left and right brakes, and a switch for raising and lowering an implement.

[0027] The operation terminal 192 is a terminal through which a user performs operations related to the travel of the work vehicle and the operation of the implements, and is also referred to as a virtual terminal (VT). The operation terminal 192 may include a touchscreen display and / or one or more buttons. The display may be, for example, a liquid crystal display (LCD) or an organic light-emitting diode (OLED) display. By operating the touchscreen of the operation terminal 192, a user can perform various operations, such as switching the autonomous driving mode on / off, recording or editing an environmental map, setting a target route, changing control variables for the work vehicle, such as vehicle speed or engine RPM, and switching implements on / off. Furthermore, in an embodiment of the present disclosure, by operating the touchscreen, an operation can be performed to switch on / off a limit mode that limits the fuel injection amount or maximum torque output of the diesel engine. The limiting of the fuel injection amount will be described in detail later. At least some of these operations can also be performed by operating the operation switch group 191. For example, an operation to switch on / off a limit mode that limits the fuel injection amount of the diesel engine can also be performed by operating a switch. The operation terminal 192 may be configured to be detachable from the work vehicle. A user located away from the work vehicle may operate the detached operation terminal 192 to control the operation of the work vehicle.

[0028] In this specification, a switching means such as a switch that allows a user to switch between various functions or settings, or a button displayed on a display device, may be referred to as an "operating device."

[0029] Work vehicle 200 further includes a travel control device (hereinafter simply referred to as the "control device") that controls the travel of work vehicle 200, an engine control device that controls the diesel engine, and a storage device. Each of the control device and engine control device includes one or more electronic control units (ECUs). The control device includes, for example, a speed control ECU that controls the speed of the work vehicle, a steering control ECU that controls the steering, and an implement control ECU that controls the operation of the three-point linkage and PTO axle included in coupling device 208, and may further include an automatic driving control ECU that performs calculations and control to achieve automatic driving.

[0030] <Configuration of Control System> The work vehicle 200 according to the embodiment of the present disclosure is equipped with a control system that controls the amount of fuel injected into the diesel engine.

[0031] However, the control system described below can also be retrofitted to a work vehicle (agricultural machinery or construction machinery) that does not have the functions implemented in the system. The control system can facilitate energy-saving operation while improving user convenience. Such a system can be manufactured and sold independently of the work vehicle. The computer program (or program module) used in such a system can also be manufactured and sold independently of the work vehicle. The computer program can be provided, for example, by being stored on a computer-readable non-transitory storage medium. The computer program can also be provided by downloading via a telecommunications line (e.g., the Internet).

[0032] FIG. 3 is a block diagram showing an example of the hardware configuration of the control system 500.

[0033] 3 includes an operation device 510, an accelerator opening sensor 520, a cruise control device (or control device) 530, and a storage device 540. These devices and an engine control device 600 are connected via a bus conforming to a vehicle bus standard such as a Controller Area Network (CAN), enabling them to communicate with each other.

[0034] As described above, the operation device 510 may be a switch for the user to switch between various functions or settings, or a button displayed on a display device. The operation device 510 allows the user to switch on / off a limit mode that limits the fuel injection amount or maximum torque output of the diesel engine.

[0035] The accelerator opening sensor 520 is a sensor for measuring the accelerator opening. Examples of the accelerator opening sensor 520 include a throttle position sensor and an accelerator pedal position sensor.

[0036] The control device 530 is configured to change the control of the fuel injection amount in response to a change in a signal indicating the on / off state of the limit mode, which is output from the operation device 510. In an embodiment of the present disclosure, the control device 530 may send to the engine control device 600 a signal indicating whether the limit of the fuel injection amount is enabled or disabled. However, the control device 530 may also send to the engine control device 600 a command value indicating a reduction rate [%] of the fuel injection amount. Here, the limit mode is a mode in which the fuel injection amount is limited so as to generate a torque smaller than the torque generated by the diesel engine at the same engine speed when the limit mode is in the off state.

[0037] The control device 530 is configured to switch between enabling and disabling the restriction of the fuel injection amount based on the difference between the command value of the engine speed and the actual measured value of the engine speed. The control device 530 is configured to switch between enabling and disabling the restriction of the fuel injection amount based on the amount of fluctuation in the actual measured value of the engine speed or the amount of fluctuation in the command value of the engine speed while the restriction mode is on.

[0038] 4 is a block diagram showing an example of the hardware configuration of an ECU according to an embodiment of the present disclosure. The ECU included in the control device 530 includes, for example, one or more processors 531, an input I / F 532, an output I / F 533, a read-only memory (ROM) 534, a random access memory (RAM) 535, a bus I / F 536, and a power supply circuit 537. Software (or firmware) for causing the one or more processors to execute at least one process may be implemented in the ROM 534. Such software may be recorded on a computer-readable recording medium or provided to a user via a network.

[0039] The processor 531 is a semiconductor integrated circuit and includes a central processing unit (CPU). The processor 531 may be implemented by a microprocessor or a microcontroller. The processor 531 sequentially executes a computer program (or a program module) stored in the ROM 534, which describes a group of instructions for executing at least one process, to achieve the desired process.

[0040] In addition to or instead of the processor 531, the ECU (or control device 530) may include an FPGA (Field Programmable Gate Array) equipped with a CPU, a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), an ASSP (Application Specific Standard Product), or a combination of two or more circuits selected from these circuits.

[0041] The input I / F 532 is an input circuit that receives digital or analog signals output from various sensors, and the output I / F 533 is an output circuit that outputs signals for driving actuators, lamps, and the like.

[0042] The ROM 534 is, for example, a writable memory (e.g., a PROM), a rewritable memory (e.g., a flash memory), or a read-only memory. The ROM 534 stores a program that controls the operation of the processor 531. The ROM 534 does not need to be a single recording medium, but may be a collection of multiple recording media. Some of the collection of multiple recording media may be removable memories.

[0043] The RAM 535 provides a working area for temporarily loading the control program stored in the ROM 534 at boot time. The RAM 535 does not have to be a single recording medium, but may be a collection of multiple recording media.

[0044] The bus I / F 536 is a bus interface for connecting the ECU to, for example, a CAN bus.

[0045] The power supply circuit 537 is a circuit that steps down a relatively high external voltage to generate a relatively low voltage required by each of the processor 531, the ROM 534, and the RAM 535.

[0046] Referring again to Figure 3, storage device 540 includes one or more storage media, such as a flash memory or a magnetic disk. Such a computer program may be provided to work vehicle 200 via a storage medium (e.g., a semiconductor memory or an optical disk) or via an electric communication line (e.g., the Internet). Such a computer program may also be sold as commercial software.

[0047] The notification device 550 is, for example, a display device such as a VT or a terminal device used by a user, a buzzer, an indicator lamp of a switch, an indicator displayed on a meter panel unit, or a meter lamp mounted on a meter panel unit. The notification device 550 can notify the user of the on / off state of the restriction mode. The notification device 550 can also notify the user of the enabled / disabled state of the restriction of the fuel injection amount.

[0048] <Control Method for Controlling Fuel Injection Amount> The control method for controlling the fuel injection amount according to this embodiment is implemented in a computer and causes the computer to receive a signal indicating the on / off state of a limit mode for limiting the fuel injection amount and to change the control of the fuel injection amount in response to a change in the signal. According to this control method, when the limit mode is set to on by a user, the control device periodically or cyclically determines whether a predetermined condition is satisfied based on the amount of fluctuation in the actual engine speed or the amount of fluctuation in the indicated engine speed, and automatically switches the fuel injection amount limit on or off depending on the determination result. As a result, when the limit mode is on and the computer determines that the fuel injection amount limit is enabled, the fuel injection amount is reduced. This makes it possible to easily achieve energy-saving operation while improving user convenience.

[0049] [1. First Implementation Example] FIG. 5 is a flowchart showing a procedure for controlling the fuel injection amount according to a first implementation example of the control method in the embodiment of the present disclosure.

[0050] 5 includes the processes of steps S10 to S18. The control device 530 repeatedly executes the processes of steps S10 to S18 while the engine ignition is on, for example.

[0051] (Step S10) The control device 530 is configured to detect a change in the signal indicating the on / off state of the limit mode, which is output from the operation device 510. When the limit mode changes from the off state to the on state or from the on state to the off state due to an operation by the user, the control device 530 determines whether or not to limit the fuel injection amount in response to the change.

[0052] (Step S11) When the restriction mode changes from the OFF state to the ON state (YES in step S10), control device 530 acquires an accelerator opening command value and an actual measurement value of the engine speed. Specifically, control device 530 acquires the accelerator opening command value generated based on the sensor data output from accelerator opening sensor 520.

[0053] In the first implementation example, the engine control device 600 acquires sensor data indicating an actual measurement value of the engine speed, which is output from a sensor that detects the engine speed (e.g., a crankshaft sensor or a camshaft sensor). The control device 530 acquires the actual measurement value of the engine speed from the engine control device 600.

[0054] (Step S12) When the limit mode changes from the ON state to the OFF state, or while it remains in the OFF state (NO in step S10), the control device 530 sets the fuel injection amount limit to OFF and transmits a signal indicating that the fuel injection amount limit is disabled to the engine control device 600. This causes the engine control device 600 to perform normal engine control without limiting the fuel injection amount. In other words, the engine control device 600 performs engine control with a fuel injection amount that provides the maximum torque output.

[0055] (Step S13) The control device 530 determines the command value of the engine speed based on the accelerator opening command value. The command value of the engine speed does not depend on the limit mode. In other words, the command value of the engine speed does not change whether the limit mode is on or off. The control device 530 can estimate the command value of the engine speed by further considering the engine characteristics, the engine load state, sensor values ​​indicated by sensor data output from various sensors, etc.

[0056] (Step S14) Control device 530 calculates the difference between the command value of the engine rotation speed and the actual measured value of the engine rotation speed. In other words, control device 530 calculates the difference between the target value of the engine rotation speed and the actual measured value of the engine rotation speed.

[0057] (Step S15) While the limit mode is on, the control device 530 determines whether two conditions are met: condition (A): the difference between the command value of the engine speed and the actual measured value of the engine speed is equal to or greater than a first threshold value; and condition (B): the amount of fluctuation in the actual measured value of the engine speed is equal to or greater than a second threshold value. Each of the first and second threshold values ​​is adjusted depending on, for example, the characteristics or type of the engine.

[0058] 6 is a graph illustrating time-series changes in engine speed and fluctuations in engine speed. The vertical axis represents engine speed [rpm], and the horizontal axis represents time [s]. The solid line in the graph represents changes in engine speed, and the dashed line represents changes in fluctuations in engine speed.

[0059] The actual measured value of the engine speed is, for example, acquired by the engine control device 600 periodically or periodically (for example, every 10 ms) and transmitted to the control device 530. Time series data indicating the actual measured value of the engine speed acquired during a specific period is stored, for example, in the storage device 540. The control device 530 determines the amount of fluctuation in the actual measured value of the engine speed by, for example, calculating a moving average of the time series data of the actual measured value of the engine speed acquired during a period from the present time up to 500 ms ago.

[0060] If the above conditions (A) and (B) are satisfied, the control device 530 sets the fuel injection amount restriction to ON (YES in step S15). This enables the fuel injection amount restriction. On the other hand, if at least one of the above conditions (A) or (B) is not satisfied, the control device 530 proceeds to step S17 (NO in step S15).

[0061] (Step S16) While the fuel injection amount restriction is in the on state, i.e., active, the control device 530 restricts the fuel injection amount so that the diesel engine generates a torque smaller than the torque generated at the same engine speed when the restriction mode is in the off state. This restricts the maximum torque output generated at the same engine speed when the restriction mode is in the off state. The control device 530 transmits a signal indicating the activation of the fuel injection amount restriction to the engine control device 600. The engine control device 600 controls the fuel injection amount so that the limited maximum torque output is not exceeded.

[0062] 7 is a graph illustrating the relationship between engine speed and fuel injection amount. The vertical axis represents the fuel injection amount [mm ３ / st], and the horizontal axis represents engine speed [rpm]. The engine torque of a diesel engine depends on the fuel injection amount. Therefore, the fuel injection amount on the vertical axis corresponds to the engine torque. FIG. 7 shows a full load torque curve when the accelerator opening (or throttle valve) is fully open. The solid line is the torque curve when the fuel injection amount limit is OFF, and the dashed line is the torque curve when the fuel injection amount limit is ON.

[0063] In an embodiment of the present disclosure, at the same engine speed, the fuel injection amount when the fuel injection amount limiting is on can be limited to, for example, 80 to 95% of the fuel injection amount when the fuel injection amount limiting is off. In other words, the engine load factor can be 80 to 95%. The engine load factor is expressed as the ratio of generated torque to maximum torque at a certain engine speed. Generally, when the engine load factor is low, the fuel injection amount is suppressed, and when the engine load factor is high, the fuel injection amount is increased. The engine load factor can be adjusted depending on the characteristics or type of engine so as to obtain a sufficient fuel reduction effect. By limiting the fuel injection amount, a reduction rate of, for example, 5 to 20% can be achieved.

[0064] A different torque curve is determined depending on the accelerator position. For example, a torque curve defining the relationship between engine speed and fuel injection amount is stored in a storage device as table data that can be read by a computer. The table data can be optimized during the engine development or adjustment phase. Even if the engine speed is the same, the fuel injection amount or torque varies depending on the accelerator position. The engine control device 600 references the table to estimate the fuel injection amount or maximum torque output based on the engine speed and accelerator position, and controls the fuel injection amount so that it does not exceed the torque output limited according to the reduction rate. This reduces fuel consumption while the fuel injection amount is limited, improving fuel efficiency. However, because the fuel injection amount is limited, the engine speed reaches the specified value (target engine speed), but the time to reach this value is somewhat longer than when the fuel injection amount is not limited.

[0065] (Step S17) Referring again to FIG. 5 , if at least one of the above conditions (A) and (B) is not satisfied, the control device 530 determines whether the following two conditions are satisfied: condition (C): the difference between the command value of the engine speed and the actual measured value of the engine speed is less than a first threshold value; or condition (D): the amount of fluctuation in the actual measured value of the engine speed while the engine speed is decreasing is equal to or greater than a third threshold value. The third threshold value is adjusted, for example, depending on the characteristics or type of the engine.

[0066] If either the above condition (C) or (D) is satisfied, the control device 530 turns off the limit on the fuel injection amount (YES in step S17). This disables and cancels the limit on the fuel injection amount. On the other hand, if neither the above condition (C) nor (D) is satisfied, the process proceeds to step S19 (NO in step S17).

[0067] (Step S18) The control device 530 turns off the limit on the fuel injection amount. Specifically, the control device 530 transmits a signal indicating that the limit on the fuel injection amount is disabled to the engine control device 600. In response to the signal, the engine control device 600 cancels the limit on the fuel injection amount.

[0068] (Step S19) The control device 530 maintains the setting of the limit on the fuel injection amount. As a result, if the limit on fuel injection is valid, the valid setting is maintained, and if the limit on fuel injection is invalid, the invalid setting is maintained.

[0069] 8 is a graph showing how the fuel injection amount is limited and changes over time by turning the fuel injection amount limit on and off. The vertical axis, from the top, represents the engine speed [rpm], the accelerator opening command value [%], and the fuel injection amount [mm ３ / st] and the ON or OFF state of the fuel injection amount restriction, and the horizontal axis represents time [s].

[0070] When the above conditions (A) and (B) are satisfied, the control device 530 changes the fuel injection amount restriction signal from OFF to ON (step S16 in FIG. 5), and the engine control device 600 starts restricting the fuel injection amount in synchronization with this signal change. On the other hand, when the control device 530 changes the fuel injection amount restriction signal from ON to OFF (step S18 in FIG. 5), the engine control device 600 releases the fuel injection amount restriction in synchronization with this signal change. In this way, the control device 530 can automatically switch the fuel injection amount restriction ON and OFF while the restriction mode is set to ON.

[0071] 9 is a schematic diagram showing an example of a display screen displaying a notification message 700 notifying the user of the on / off state of the restricted mode. Fig. 9 shows an example of a screen of the operation terminal 192 displaying a camera image including the notification message 700. In an embodiment of the present disclosure, the operation terminal 192 functions as the notification device 550.

[0072] The operation terminal 192 may display a notification message 700 on the screen notifying the user of the on or off state of the restriction mode. The operation terminal 192 may further display a notification message 700 on the screen including the enabled or disabled state of the fuel injection amount restriction. Such a notification allows the user to recognize the internal state of the work vehicle. However, for example, a dedicated indicator may be provided on the meter panel unit, and the on or off state of the restriction mode may be notified to the user by turning the indicator on or off.

[0073] [2. Second Implementation Example] The second implementation example differs from the first implementation example in that the engine load factor is taken into consideration when determining whether or not to limit the fuel injection amount.

[0074] FIG. 10 is a flowchart showing a procedure for controlling the fuel injection amount according to a second implementation example of the control method in the embodiment of the present disclosure.

[0075] The processing flow illustrated in Fig. 10 includes steps S20 to S28. The steps S20 to S28 correspond to steps S10 to S18 in Fig. 5 in the first implementation example, respectively. The steps S20, S22 to S24, and S26 to S29 are common to steps S10, S12 to S14, and S16 to S19 in the first implementation example, and therefore descriptions of these steps will be omitted. The steps S21 and S25 will be described in detail below.

[0076] In step S21, the control device 530 acquires an accelerator opening command value and an actual measurement value of the engine speed, and further acquires the engine load factor from the engine control device 600.

[0077] In step S25, while the limit mode is on, the control device 530 determines whether the following two conditions are met: condition (A): the difference between the command value of the engine speed and the actual measured value of the engine speed is equal to or greater than a first threshold value; and condition (E): the amount of fluctuation in the command value of the engine speed is equal to or greater than a fifth threshold value when the engine load factor is less than a fourth threshold value. Each of the fourth and fifth threshold values ​​is adjusted depending on, for example, the characteristics or type of the engine.

[0078] Condition A is the same as condition (A) in the first implementation example. In condition (E), if the engine load factor is less than the fourth threshold value, it means that the engine is in a relatively low load state, and if the engine load factor is equal to or greater than the fourth threshold value, it means that the diesel engine is in a relatively high load state.

[0079] The control device 530 may determine the amount of fluctuation in the indicated value of the engine speed as the difference between the latest indicated value of the engine speed in time series and the indicated value of the engine speed obtained immediately before the latest indicated value of the engine speed. Alternatively, similar to the amount of fluctuation in the actual measured value of the engine speed described in the first implementation example, the control device 530 may determine the amount of fluctuation in the indicated value of the engine speed by, for example, calculating a moving average of time-series data of indicated values ​​of the engine speed obtained during the period from the present time to 500 ms ago.

[0080] If the above conditions (A) and (E) are satisfied, the control device 530 sets the fuel injection amount restriction to ON (YES in step S25). This enables the fuel injection amount restriction. On the other hand, if at least one of the above conditions (A) or (E) is not satisfied, the control device 530 proceeds to step S27 (NO in step S25).

[0081] In this way, the control device 530 can automatically limit the fuel injection amount according to the engine load factor while the limit mode is on. According to the second implementation example, the control device 530 can quickly determine whether to limit the fuel injection amount when the engine is in a low load state, thereby improving the fuel efficiency.

[0082] According to an embodiment of the present disclosure, energy-saving operation can be achieved relatively easily. The user can switch the limit mode on and off by operating the input device. In particular, once the limit mode is set to on, the control device automatically determines whether or not limiting the fuel injection amount is necessary depending on the engine load state, and then limits the fuel injection amount. This can significantly reduce the effort required for user operation.

[0083] Conventional technologies require a transmission to maintain vehicle speed when engine speed is reduced, or a PTO gear to maintain PTO shaft rotation speed, making it difficult to achieve energy-saving operation in work vehicles equipped with transmissions that cannot be electronically controlled. In contrast, embodiments of the present disclosure limit the fuel injection amount rather than the engine speed, making it possible to maintain engine speed regardless of the presence or absence of a PTO gear. For example, the PTO shaft rotation speed can be maintained at a rated speed (e.g., 540 rpm). This reduces the impact of a reduction in PTO shaft rotation speed on the work being performed by the user. Furthermore, the technology of the present disclosure can be widely applied to general work vehicles, regardless of whether the transmission is electronically controlled.

[0084] As described above, the present disclosure includes a control system, a control method, and a work vehicle for controlling the fuel injection amount of a diesel engine, as described in the following items.

[0085] [Item 1] A control system for controlling a fuel injection amount of a diesel engine mounted on a work vehicle, comprising: an operating device for switching between an on / off state of a limit mode for limiting the fuel injection amount; and a control device that changes control of the fuel injection amount in response to a change in a signal that indicates the on / off state of the limit mode, output from the operating device; wherein the limit mode is a mode that limits the fuel injection amount so that the diesel engine generates a torque that is smaller than the torque generated at the same engine speed when the limit mode is in the off state.

[0086] [Item 2] The control system according to Item 1, wherein the control device acquires an accelerator opening command value, and the command value of the engine speed determined based on the accelerator opening command value does not change depending on whether the limit mode is in an on state or an off state.

[0087] [Item 3] The control system according to Item 2, wherein the control device acquires an actual measurement value of an engine speed, and while the limit mode is in an on state, switches between enabling and disabling the limit on the fuel injection amount based on an amount of fluctuation in the actual measurement value of the engine speed or an amount of fluctuation in an indicated value of the engine speed.

[0088] [Item 4] The control system according to Item 3, wherein the control device switches between validity and invalidity of the limit on the fuel injection amount based on a difference between the command value of the engine speed and the actual measured value of the engine speed.

[0089] [Item 5] The control system according to Item 4, wherein while the limit mode is in an on state, the control device enables the limit on the fuel injection amount when the difference between the command value of the engine speed and the actual measured value of the engine speed is equal to or greater than a first threshold value and an amount of fluctuation in the actual measured value of the engine speed is equal to or greater than a second threshold value.

[0090] [Item 6] In the control system according to Item 4, while the limit mode is in an on state, the control device disables the limit on the fuel injection amount when one of the following conditions is satisfied: the difference between the command value of the engine speed and the actual measured value of the engine speed is less than a first threshold value; or an amount of fluctuation in the actual measured value of the engine speed while the engine speed is decreasing is equal to or greater than a third threshold value.

[0091] [Item 7] The control device further acquires an engine load factor, and while the limit mode is in an on state, when the difference between the command value of the engine speed and the actual measured value of the engine speed is equal to or greater than a first threshold value and when the engine load factor is less than a fourth threshold value, a fluctuation amount of the command value of the engine speed is equal to or greater than a fifth threshold value, the control system according to item 4 enables the limit of the fuel injection amount.

[0092] [Item 8] The control system according to any one of Items 4 to 7, wherein the control device transmits a signal indicating whether the restriction of the fuel injection amount is enabled or disabled to an engine control device that controls the operation of the diesel engine.

[0093] [Item 9] The control system according to any one of items 3 to 8, further comprising a notification device that notifies a user of the on or off state of the restricted mode.

[0094] [Item 10] The control system according to Item 8, wherein the notification device notifies whether the restriction on the fuel injection amount is enabled or disabled.

[0095] [Item 11] A work vehicle comprising: a diesel engine; and the control system according to any one of items 1 to 10.

[0096] [Item 12] The work vehicle according to Item 11, further comprising a coupling device for connecting an implement, wherein power is supplied from the diesel engine to the implement via the coupling device.

[0097] [Item 13] A control method implemented in a computer for controlling a fuel injection amount of a diesel engine mounted on a work vehicle, the control method comprising: receiving a signal indicating an on / off state of a limit mode for limiting the fuel injection amount; and changing control of the fuel injection amount in response to a change in the signal; wherein the limit mode is a mode for limiting the fuel injection amount so as to generate a torque smaller than the torque generated by the diesel engine at the same engine speed when the limit mode is off.

[0098] The embodiments of the present disclosure can be suitably used in work vehicles such as agricultural machinery or construction machinery.

[0099] 100...meter panel unit, 191...operation switch group, 192...operation terminal, 200...work vehicle, 201...vehicle body, 202...motor, 203...transmission device, 204...tired wheel, 204...wheel, 204F...front wheel, 204R...rear wheel, 205...cabin, 207...driver's seat, 208...coupling device, 220...steering wheel, 260...GNSS unit, 270...camera, 290... LiDAR sensor, 295: Obstacle sensor, 300: Implement, 500: Control system, 510: Operation device, 520: Accelerator opening sensor, 530: Control device, 531: Processor, 532: Input I / F, 533: Output I / F, 534: ROM, 535: RAM, 536: Bus I / F, 537: Power supply circuit, 540: Storage device, 550: Notification device, 600: Engine control device

Claims

1. A control system for controlling the fuel injection amount of a diesel engine mounted on a work vehicle, comprising: an operating device for switching the on / off state of a limit mode for limiting the fuel injection amount; and a control device that changes the control of the fuel injection amount in response to a change in a signal indicating the on / off state of the limit mode output from the operating device, wherein the limit mode is a mode in which the fuel injection amount is limited so that the diesel engine generates a torque smaller than the torque generated at the same engine speed when the limit mode is in the off state.

2. The control system according to claim 1, wherein the control device acquires an accelerator opening instruction value, and the instruction value of the engine speed determined based on the accelerator opening instruction value does not change depending on whether the limit mode is on or off.

3. The control system according to claim 2, wherein the control device acquires an actual measurement value of the engine speed, and switches the validity of the limitation of the fuel injection amount based on the amount of change in the actual measurement value of the engine speed or the amount of change in the instruction value of the engine speed while the limit mode is on.

4. The control system according to claim 3, wherein the control device switches the validity of the limitation of the fuel injection amount further based on the difference between the instruction value of the engine speed and the actual measurement value of the engine speed.

5. The control system according to claim 4, wherein while the limit mode is on, the control device enables the limitation of the fuel injection amount when the difference between the instruction value of the engine speed and the actual measurement value of the engine speed is equal to or greater than a first threshold value and the amount of change in the actual measurement value of the engine speed is equal to or greater than a second threshold value.

6. The control system according to claim 4, wherein while the limit mode is on, the control device disables the limitation of the fuel injection amount when either one of the following conditions is satisfied: the difference between the instruction value of the engine speed and the actual measurement value of the engine speed is less than a first threshold value; or the amount of change in the actual measurement value of the engine speed when the engine speed is decreasing is equal to or greater than a third threshold value.

7. The control device further obtains an engine load rate, and while the limit mode is on, when the difference between the commanded engine speed and the measured engine speed is greater than or equal to a first threshold value and the engine load rate is less than a fourth threshold value, and when the amount of change in the commanded engine speed is greater than or equal to a fifth threshold value, the control system according to claim 4, wherein the restriction of the fuel injection amount is made effective.

8. The control device according to any one of claims 4 to 7, wherein the control device transmits a signal indicating whether the restriction of the fuel injection amount is effective or ineffective to an engine control device that controls the operation of the diesel engine.

9. The control system according to any one of claims 3 to 7, further comprising a notification device that notifies the user of the on or off state of the limit mode.

10. The control system according to claim 8, wherein the notification device notifies the state of whether the restriction of the fuel injection amount is effective or ineffective.

11. A work vehicle comprising a diesel engine and the control system according to any one of claims 1 to 7.

12. The work vehicle according to claim 11, further comprising a coupling device for connecting an implement, wherein power is supplied from the diesel engine to the implement via the coupling device.

13. A control method for controlling the fuel injection amount of a diesel engine mounted on a work vehicle, implemented on a computer, the method comprising: receiving a signal indicating the on / off state of a limit mode for restricting the fuel injection amount; and changing the control of the fuel injection amount in response to a change in the signal, wherein the computer is caused to execute the method, and the limit mode is a mode in which the fuel injection amount is restricted so that the diesel engine generates a torque smaller than the torque generated at the same engine speed when the limit mode is off.

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