Field working machine

Abstract

To provide a field working machine which enables driving of a work device and travel assisting to be performed properly.SOLUTION: An exemplary field working machine includes: a traveling machine body having a traveling device; a work device supported by the traveling machine body; a prime mover which supplies driving force to the traveling device; a first rotary electric machine which is connected to an output shaft of the prime mover in a manner that enables power transmission thereto; and a second rotary electric machine which supplies driving force to the work device.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Conventionally, there is known a hybrid work vehicle in which an internal combustion engine is assisted by a motor generator (see, for example, Patent Document 1). In a hybrid work vehicle, the vehicle is driven by power from the internal combustion engine, and when a large load is generated on the internal combustion engine, the motor generator is operated as a motor to assist the output of the internal combustion engine. When the motor generator is not assisting the output of the internal combustion engine, it operates as a generator and charges the battery.

[0003] In the hybrid work vehicle of Patent Document 1, the internal combustion engine supplies driving force to a traveling device and a working device via a power transmission means. The output of the internal combustion engine is assisted by outputting power from the motor generator to the power transmission means. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-65349 A Summary of the Invention [Problem to be solved by the invention]

[0005] In a configuration in which the traveling device and the working device are driven via a power transmission means, the driving speed of the traveling device and the driving speed of the working device are linked. In such a configuration, for example, even if slippage occurs in the traveling wheels, the working device operates at a speed linked to the driving speed of the traveling device regardless of the slippage. For this reason, for example, if the working device is a planting device, the occurrence of slippage may cause a situation in which the planting interval becomes shorter than the target interval.

[0006] An object of the present invention is to provide a field work machine that is capable of appropriately driving a work implement and providing traveling assistance. [Means for solving the problem]

[0007] An exemplary field work machine of the present invention comprises a traveling body having a traveling device, a work device supported on the traveling body, a prime mover that supplies driving force to the traveling device, a first rotating electric machine connected to an output shaft of the prime mover so as to be capable of transmitting power, and a second rotating electric machine that supplies driving force to the work device. Effect of the Invention

[0008] According to the exemplary embodiment of the present invention, driving of the work implement and traveling assistance in a field work machine can be performed appropriately. [Brief description of the drawings]

[0009] [Figure 1] A diagram showing the basic configuration of a farm implement [Diagram 2] FIG. 2 is a diagram showing a modified example of the basic configuration of the field work machine shown in FIG. [Diagram 3] A side view showing the general configuration of a rice transplanter [Figure 4] A plan view showing the general configuration of a rice transplanter [Diagram 5] FIG. 1 is a plan view showing a schematic configuration of a power transmission mechanism provided in a rice transplanter; [Figure 6] FIG. 1 is a diagram showing a schematic configuration of a control system in a farm implement; [Figure 7] 1 is a flowchart showing an example of a control operation of a motor generator by a control device. [Figure 8] A flowchart illustrating a process executed by the control device to acquire a road load. [Figure 9] FIG. 1 is a diagram for explaining an example of calculating a running load using a load calculation map; [Figure 10] FIG. 9 is a diagram for explaining the rotation speed correction executed in the process shown in FIG. 8; [Figure 11]8 is a flowchart showing a modified example of the control operation by the control device described in FIG. 7. [Figure 12] A block diagram showing the general configuration of a system for controlling engine revolutions of an agricultural work machine. [Figure 13] FIG. 1 is a diagram for explaining engine rotation control in a farm work machine equipped with a travel assist function. [Figure 14] FIG. 1 is a diagram for explaining engine rotation control in a farm work machine equipped with a travel assist function. [Figure 15A] 1 is a flowchart illustrating an example of a flow of engine rotation control executed by a control device. [Figure 15B] 1 is a flowchart illustrating an example of a flow of engine rotation control executed by a control device. [Figure 16] FIG. 1 is a block diagram showing a modified example of a system for controlling engine revolutions. [Figure 17] FIG. 1 is a diagram showing an example of the operation of a farm work machine in a farm field. [Figure 18] Graph showing the change in remaining battery capacity over time when power generation control according to the present embodiment is performed DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference characters and description thereof will not be repeated.

[0011] In this specification, the term "rotating electric machine" is used as a concept that includes any of a motor (electric motor), a generator (electric generator), and a motor generator that functions as both a motor and a generator as necessary.

[0012] <1. Basic configuration of farm machinery> FIG. 1 is a diagram showing the basic configuration (basic structure) of a field work machine 100 according to an embodiment of the present invention. In FIG. 1, thick solid lines connecting elements indicate power lines. Furthermore, thick dashed lines connecting elements indicate signal lines. Furthermore, hollow arrows indicate the direction of power transmission. In the figure, "F" indicating directions is the front side, "B" is the rear side, "L" is the left side, and "R" is the right side. This is also true in other figures other than FIG. 1. In addition, although not shown in FIG. 1, directions "U" and "D" shown in other figures are the upside and downside, respectively.

[0013] The field work machine 100 broadly includes a work machine that performs work while traveling in a field. The field work machine 100 may be, for example, a rice transplanter, a tractor, a combine harvester, a seeding machine, a transplanter, or a chemical sprayer. As shown in Fig. 1, the field work machine 100 includes a traveling machine body 1, a work device 2, a prime mover 3, a first rotating electric machine 4, a second rotating electric machine 5, and a battery 6.

[0014] The traveling body 1 enables the field work machine 100 to travel in a field. The traveling body 1 has a body frame 11 and a traveling device 12. The body frame 11 forms the framework of the field work machine 100. The traveling device 12 supports the body frame 11 so that it can travel. The traveling device 12 is configured using, for example, wheels or crawlers. In this embodiment, the traveling device 12 is configured using a pair of left and right front wheels 12a and a pair of left and right rear wheels 12b.

[0015] The working device 2 is supported by the machine body frame 11. In other words, the working device 2 is supported by the traveling machine body 1. In this specification, being supported by the machine body frame 11 (traveling machine body 1) includes both a configuration in which the working device is directly supported by the machine body frame 11 (traveling machine body 1) and a configuration in which the working device is indirectly supported by the machine body frame 11 (traveling machine body 1). The working device 2 may be supported so as to be movable (e.g., rotatable) relative to the machine body frame 11. The working device 2 is, for example, a planting device, a reaping device, a tilling device, a fertilizing device, a grass cutting device, or a seeding device. In this embodiment, the working device 2 is disposed behind the machine body frame 11, but this is merely an example, and the working device 2 may be disposed in front of or to the side of the machine body frame 11.

[0016] The prime mover 3 is supported by the vehicle frame 11. The prime mover 3 supplies driving force to the traveling device 12. In this embodiment, the prime mover 3 is preferably an engine. Hereinafter, the prime mover 3 will be referred to as the engine 3, which is a representative example. The engine 3 is, for example, a diesel engine, a gasoline engine, a hydrogen engine, or a gas engine. The output of the engine 3 is transmitted to the traveling device 12 via a transmission (not shown). However, the transmission is not an essential component. Furthermore, the drive control of the engine 3 is performed by a control device (not shown).

[0017] In FIG. 1, the output of the engine 3 is shown to be transmitted to only one wheel (the left front wheel 12a), but this is merely for convenience of description. In this embodiment, the output of the engine 3 is transmitted to the left and right front wheels 12a and the rear wheels 12b. However, the output of the engine 3 may be transmitted to only the left and right front wheels 12a or the left and right rear wheels 12b. In this embodiment, the output of the engine 3 may be output to the first rotating electric machine 4 in some cases. This will be described later.

[0018] The first rotating electric machine 4 is supported by the machine frame 11. The first rotating electric machine 4 is connected to the output shaft of the engine 3 so as to be capable of transmitting power. In detail, the first rotating electric machine 4 is connected to the engine 3 via a power transmission unit (not shown). The power transmission unit broadly includes a configuration capable of transmitting power. The power transmission unit may be configured to directly or indirectly connect the output shaft of the engine 3 and the rotating shaft of the first rotating electric machine 4. The power transmission unit may be configured to connect the output shaft of the engine 3 and the rotating shaft of the first rotating electric machine 4 with a power transmission shaft or via a speed change device. In addition, the first rotating electric machine 4 may be capable of switching the power transmission state between the engine 3 and the first rotating electric machine 4 to either a connected state or a disconnected state using a clutch.

[0019] The first rotating electric machine 4 may be configured to provide power to the output of the engine 3. That is, the first rotating electric machine 4 may be configured to function as a motor to assist the output of the engine 3. The first rotating electric machine 4 may be configured to generate power by being rotated by the output of the engine 3. That is, the first rotating electric machine 4 may be configured to function as a generator by the output of the engine 3. The first rotating electric machine 4 may be configured to have the above-mentioned two functions. That is, the first rotating electric machine 4 may be configured to have both functions of functioning as a motor to assist the output of the engine 3 and functioning as a generator by being rotated by the output of the engine 3.

[0020] In the present embodiment, the first rotating electric machine 4 is preferably a motor generator. That is, the first rotating electric machine 4 can perform both functions of assisting the output of the engine 3 as a motor and generating electricity by rotating with the output of the engine 3. Hereinafter, the first rotating electric machine 4 will be referred to as a motor generator 4, which is a representative example. More specifically, the motor generator 4 functions as a three-phase AC motor when three-phase AC power is input, and rotates when power is input to function as a three-phase AC generator. By providing the motor generator 4, it is possible to assist the output of the engine 3 to the traveling device 12 (wheels). The motor generator 4 is controlled by a control device (not shown) via the first inverter 7a.

[0021] The second rotating electric machine 5 is supported by the machine body frame 11. The second rotating electric machine 5 supplies driving force to the working device 2. That is, in this embodiment, power is transmitted to the working device 2 from a power source provided separately from the engine 3. With this configuration, the working device 2 can be driven without being affected by fluctuations in the load on the engine 3.

[0022] In this embodiment, as a preferred embodiment, the second rotating electric machine 5 is a motor. Hereinafter, the second rotating electric machine 5 will be referred to as a motor 5, which is a representative example of the second rotating electric machine 5. More specifically, the motor 5 is a three-phase AC motor driven by three-phase AC power. The motor 5 is controlled by a control device (not shown) via a second inverter 7b.

[0023] The battery 6 is supported by the vehicle frame 11. The battery 6 is, for example, a lithium ion battery or the like, and is a chargeable and dischargeable secondary battery. In this embodiment, the battery 6 is electrically connected to the motor generator 4 and the motor 5. In detail, the battery 6 is electrically connected to the motor generator 4 via a first inverter 7a. In addition, the battery 6 is electrically connected to the motor 5 via a second inverter 7b.

[0024] The battery 6 can supply power to the motor generator 4 via the first inverter 7a. The motor generator 4 can supply power to the battery 6 via the first inverter 7a. That is, the motor generator 4 can charge the battery 6. The battery 6 can supply power to the motor 5 via the second inverter 7b.

[0025] In detail, the first inverter 7a converts the DC power output from the battery 6 into AC power and supplies it to the motor generator 4. The first inverter 7a also converts the AC power output from the motor generator 4 into DC power and supplies it to the battery 6. The second inverter 7b converts the DC power output from the battery 6 into AC power and supplies it to the motor 5. The inverters 7a and 7b may or may not be provided depending on the type of the motor generator and the motor (e.g., AC type or DC type). Also, in this embodiment, the motor generator 4 and the motor 5 are configured to have separate inverters, but the motor generator 4 and the motor 5 may also be configured to share one inverter.

[0026] In this embodiment, the battery 6 and the first inverter 7a (motor generator 4) are provided so as to be switchable between an electrically connected state and an electrically disconnected state. The battery 6 and the second inverter 7b (motor 5) are provided so as to be switchable between an electrically connected state and an electrically disconnected state. These switching states are realized by a relay (not shown) provided in the junction box 8.

[0027] In this embodiment, a relay (not shown) is disposed between the first inverter 7a and the second inverter 7b, and can be switched between a state in which electricity flows and a state in which electricity does not flow between them. In other words, the motor generator 4 and the motor 5 are provided so as to be switchable between an electrically connected state and an electrically disconnected state. This switching is also realized by a relay (not shown) provided in the junction box 8. By electrically connecting the motor generator 4 and the motor 5, it is possible to supply electric power generated by the motor generator 4 to the motor 5.

[0028] The motor 5 can be driven by power supplied from the battery 6, or by power supplied from the motor generator 4. Furthermore, the motor 5 can be driven by power supplied from both the battery 6 and the motor generator 4. The motor generator 4 can also supply power to the motor 5 while charging the battery 6. The battery 6 can also supply power to the motor generator 4 and the motor 5 simultaneously.

[0029] It should be noted that the junction box 8 is preferably provided because it is convenient for organizing and protecting the wiring, but is not necessarily required. A configuration may be adopted in which relay wiring is provided individually without providing the junction box 8.

[0030] In the field work machine 100 having the basic configuration described above, for example, the following operation is performed. When traveling in a field, the engine 3 normally supplies driving force to the traveling device 12, and also supplies driving force to operate the motor generator 4 as a generator. Then, if the traveling load, which is the load on the engine 3 while traveling, increases and a risk of engine stall or the like is detected, power generation by the motor generator 4 is stopped, and the output of the engine 3 that was being used for power generation is used as driving force for traveling. If it is determined that the increase in the traveling load cannot be adequately handled by just stopping the power generation, the motor generator 4 is made to function as a motor to assist the output of the engine 3, and the increase in the traveling load is covered.

[0031] It should be noted that, instead of simply turning the power generation function on and off, the amount of power generation in the motor generator 4 may be increased or decreased depending on the running load.

[0032] The running load can be obtained based on control information of the engine 3 and information detected by various sensors. The running load can be calculated based on, for example, the number of revolutions of the output shaft of the engine 3, engine torque, vehicle speed, fuel injection amount, etc. An example of a method for obtaining the running load will be described later.

[0033] Figure 2 is a diagram showing a modified example of the basic configuration of the field work machine 100 shown in Figure 1. The modified field work machine 100A shown in Figure 2 has roughly the same configuration as the field work machine 100 shown in Figure 1. Descriptions of the same components will be omitted, and the following description will focus on the different parts.

[0034] As shown in Fig. 2, the modified field work machine 100A includes a switching mechanism 9 that switches the power transmission state between the motor generator 4 and the motor 5 between a connected state and a disconnected state. The switching mechanism 9 is a so-called clutch. By providing the switching mechanism 9, the following usage is possible, for example.

[0035] For example, when a malfunction occurs in a system related to electric drive using the motor 5 (electric-related system), the switching mechanism 9 may be connected as an emergency operation. In this way, the working device 2 can be driven using the output of the engine 3 instead of the output of the motor 5. A speed reduction mechanism may be provided between the switching mechanism 9 and the motor 5 as necessary. Malfunctions in the electric-related system include, for example, insufficient charging of the battery 6 and malfunctions in the electric-related system. Malfunctions in the electric-related system include, for example, malfunctions or breaks in the first inverter 7a, the second inverter 7b, the junction box 8, the motor generator 4, the motor 5, the battery 6, or wiring connected thereto.

[0036] Also, for example, when it is determined that an increase in the driving load cannot be sufficiently handled by simply having the motor generator 4 function as a motor to assist the output of the engine 3, the switching mechanism 9 may be brought into the connected state. In this way, the output of the motor generator 4 (and ultimately the engine 3) can be assisted by the driving force of the motor 5 to handle an increase in the driving load. Note that, when the driving force of the motor 5 is used to assist the output of the engine 3, it is preferable that the drive of the working device 2 is stopped. Alternatively, it is preferable that the driving force of the motor 5 is used to assist the output of the engine 3 when the working device 2 is not performing work.

[0037] <2. Rice transplanter> Next, a specific configuration example will be described when the field work machine 100 having the above-mentioned basic configuration is a rice transplanter 100R. Fig. 3 is a side view showing a schematic configuration of the rice transplanter 100R according to an embodiment of the present invention. In Fig. 3, the rear wheels 12b are shown by virtual lines (two-dot chain lines) to make it easier to understand the structure of the part that is actually hidden by the rear wheels 12b. Fig. 4 is a plan view showing a schematic configuration of the rice transplanter 100R. Fig. 5 is a plan view showing a schematic configuration of a power transmission mechanism provided in the rice transplanter 100R.

[0038] In addition, in explaining the rice transplanter 100R, the direction perpendicular to the traveling plane S (see FIG. 3) on which the rice transplanter 100R travels is defined as the up-down direction, and the rice transplanter 100R side is defined as the top with respect to the traveling plane S. The direction in which the rice transplanter 100R travels straight ahead is defined as the front-rear direction, and the front-rear direction is defined as the steering wheel 21 being the front side with respect to the driver's seat 20 (see FIG. 3 and FIG. 4). The direction perpendicular to the up-down direction and the front-rear direction is defined as the left-right direction, and the right side from the rear to the front is defined as the right side, and the left side is defined as the left side. Note that these directions are names used simply for explanation, and are not intended to limit the actual positional relationship and direction.

[0039] The rice transplanter 100R performs planting work of planting seedlings in the ground of the field while traveling in the field. As shown in Figures 3 and 4, the rice transplanter 100R includes a traveling machine body 1 and a work device 2.

[0040] The traveling machine body 1 includes a machine frame 11 and a traveling device 12. The traveling device 12 includes front wheels 12a arranged at an interval from each other in the left-right direction at the front of the machine frame 11. The traveling device 12 also includes rear wheels 12b arranged at an interval from each other in the left-right direction at the rear of the machine frame 11. An engine 3 covered from above by a bonnet 13 is arranged in the left-right center of the front of the machine frame 11. Note that in Figs. 3 and 4, the engine 3 is shown by a virtual line (broken line) because it is covered by the bonnet 13 and cannot be seen in reality. Also, the engine 3 is an example of a prime mover as described above, and is specifically a diesel engine, but may be an alternative to a diesel engine (for example, a motor, etc.). Also, the position of the engine 3 may be different from that of this embodiment.

[0041] As shown in Figures 3 and 5, a transmission 15 is disposed behind the engine 3. The transmission 15 is not an essential component. In cases where a prime mover is provided instead of an engine, a configuration without a transmission may be adopted. The transmission 15 is provided so as to be capable of varying the driving force generated by the engine 3. Front axles 16 are disposed on the left and right of the transmission 15. The front wheels 12a are attached to front wheel shafts 16a provided on the front axle 16, and are driven by the driving force transmitted from the transmission 15.

[0042] A rear axle 17 is disposed behind the transmission 15. More specifically, the rear axle 17 is connected to the transmission 15 by a joint member 18 extending in the front-rear direction. A rear-wheel drive shaft 19 is disposed along the joint member 18. The rear-wheel drive shaft 19 transmits driving force from the transmission 15 to the rear axle 17. The rear wheels 12b are attached to a rear wheel shaft 17a provided on the rear axle 17. The rear wheels 12b are driven by the driving force transmitted from the transmission 15 via the rear-wheel drive shaft 19.

[0043] Further, the motor generator 4 is connected to the transmission 15 so as to be capable of transmitting power. As described above, the motor generator 4 is an example of a first rotating electric machine. More specifically, the motor generator 4 is disposed behind the transmission 15. However, the location of the motor generator 4 is not limited to the location in this embodiment and may be changed as appropriate.

[0044] When functioning as a motor, the motor generator 4 assists the output of the engine 3 via the transmission 15. When functioning as a generator, the motor generator 4 generates electricity by rotating with the driving force from the engine 3 transmitted via the transmission 15. In this embodiment, power is transmitted so that the rotation speed of the engine 3 and the rotation speed of the motor generator 4 are the same. The electric power generated by the motor generator 4 is supplied to at least one of the battery 6 and the motor 5 via a first inverter 7a and a junction box 8.

[0045] As described above, the motor 5 is an example of the second rotating electric machine. The motor 5 is supported by the machine frame 11 above the rear axle 17. More specifically, the motor 5 is disposed in a position above the rear axle 17, to the right of the center in the left-right direction. By disposing the motor 5 in such a position, it is possible to reduce the possibility that the motor 5 will be submerged in water or soiled with mud during work in the field. However, the position of the motor 5 is not limited to this and may be changed as appropriate. The motor 5 is supplied with power from at least one of the battery 6 and the motor generator 4 via the junction box 8 and the second inverter 7b.

[0046] Although the battery 6, the first inverter 7a, the second inverter 7b, and the junction box 8 are not shown in Figures 3 to 5, these are disposed in appropriate positions on the traveling machine body 1 (preferably the machine body frame 11).

[0047] Furthermore, in this embodiment, the motor generator 4 and the motor 5 are not connected to each other so that power can be transmitted, but as in the modified example of the basic configuration described above, the motor generator 4 and the motor 5 may be connected to each other so that power can be transmitted via a switching mechanism 9. The thick dashed line in Fig. 5 typically shows a case where the motor generator 4 and the motor 5 are connected to each other so that power can be transmitted via the switching mechanism 9.

[0048] The traveling machine body 1 includes a driver's seat 20 supported by the machine body frame 11. The driver's seat 20 is disposed above the joint material 18. In front of the driver's seat 20, a steering handle 21 is disposed, which is a handle used by the operator to steer the rice transplanter 100R. In addition, around the driver's seat 20, operating devices such as a gear shift lever, a gear shift pedal, and a brake pedal (not shown) are disposed.

[0049] The traveling body 1 is equipped with spare seedling trays 22 arranged on the left-right outer side of the bonnet 13. Supplementary seedling mats are placed on the spare seedling trays 22. The spare seedling trays 22 are arranged on both the left and right sides. On each of the left and right sides, multiple spare seedling trays 22 are lined up in the vertical direction.

[0050] The working device 2 is supported by the machine frame 11. More specifically, the working device 2 is a planting device 2A. The planting device 2A is supported by the machine frame 11 so as to be able to swing up and down. The planting device 2A comprises a seedling carrier 30 on which a seedling mat is placed, and a main frame 31. The main frame 31 is a rod-shaped member extending in the left-right direction, and comprises a center case 32 (see Figures 3 and 5) in the center in the left-right direction.

[0051] The center case 32 is equipped with a gear train (not shown) including a bevel gear. A drive shaft 52 is connected to an input shaft 32a of the center case 32 via a universal joint 51. An end of the drive shaft 52 opposite to the end connected to the input shaft 32a of the center case 32 is connected to an output shaft 5a of the motor 5 via the universal joint 51. The output shaft 5a of the motor 5 extends in the front-rear direction and protrudes rearward. An output shaft 32b (see FIG. 5) of the center case 32 is disposed along the main frame 31. That is, the output shaft 32b of the center case 32 extends in the left-right direction.

[0052] In this embodiment, the output shaft 5a of the motor 5 is connected to the drive shaft 52, but this is merely an example. For example, a transmission may be connected to the output shaft 5a of the motor 5, and the transmission may be connected to the drive shaft 52. Alternatively, the output shaft 5a of the motor 5 may be directly connected to the center case 32.

[0053] Planting transmission cases 33 are arranged at approximately equal intervals at multiple locations (four locations in this embodiment as an example) in the left-right direction behind the main frame 31. The planting transmission cases 33 are connected to the output shaft 32b of the center case 32. A pair of planting units (transplanting mechanisms) 34 are arranged on the left and right of the planting transmission case 33.

[0054] Each of the pair of planting parts 34 includes a rotor case 35 and a planting claw 36. The rotor case 35 is attached to the planting transmission case 33 so as to be rotatable about an axis extending in the left-right direction. Two planting claws 36 arranged on opposite sides of the center of rotation of the rotor case 35 are rotatably attached to each rotor case 35. Each planting claw 36 is attached to the rotor case 35 so as to be rotatable about an axis extending in the left-right direction. The two planting claws 36 are displaced with the rotation of the rotor case 35. One row of seedlings is planted by displacing the two planting claws 36.

[0055] The driving force generated by the motor 5 is transmitted to the planting unit 34 via the drive shaft 52, the center case 32, and the planting transmission case 33. The planting device 2A is equipped with a lateral feed drive unit (not shown) that moves the seedling carrier 30 in the left-right direction. In parallel with the seedling carrier 30 reciprocating left and right, each planting unit 34 takes out seedlings from the seedling carrier 30 and plants them in the field. In this embodiment, since there are multiple planting units 34 (eight in detail), planting can be performed on multiple rows simultaneously.

[0056] In addition, the planting device 2A is provided so as to be movable up and down by a lifting device 37 (see FIG. 3). The lifting device 37 includes a columnar frame 371, an upper link member 372, a lower link member 373, and a hydraulic cylinder 374. The columnar frame 371 extends upward from the rear axle 17 and is connected to the rear of the machine frame 11. The upper link member 372 and the lower link member 373 form a pair of link members arranged parallel to each other. The columnar frame 371 and the seedling carrier 30 are connected by the pair of link members 372, 373. The joints between the columnar frame 371, the seedling carrier 30, and the pair of link members 372, 373 form the four vertices of a parallelogram.

[0057] The hydraulic cylinder 374 is connected to the joint material 18 and the lower link member 373. When the hydraulic cylinder 374 expands and contracts, the pair of link members 372, 373 swing around a joint on the columnar frame 371 side as a fulcrum, thereby lifting and lowering the planting device 2A. The hydraulic cylinder expands and contracts by controlling the drive of a hydraulic pump (not shown) driven by output from the engine 3.

[0058] In the rice transplanter 100R of this embodiment, power is transmitted to the planting device 2A (work device 2) from a motor 5, which is a power source provided independently of the power transmission path of the engine 3. For this reason, the planting device 2A can be driven without being affected by fluctuations in the load on the engine 3. For example, seedlings can be planted at appropriate intervals without being affected by slippage of the running wheels 12a, 12b. In addition, seedlings can be planted at any interval regardless of the traveling speed of the rice transplanter 100R.

[0059] Further, in the rice transplanter 100R, for example, the following operation is performed.

[0060] When traveling in a farm field, the engine 3 normally supplies driving force to the traveling device 12, supplies driving force to a hydraulic pump for driving the lifting device 37, and supplies driving force to operate the motor generator 4 as a generator. The electric power generated by the motor generator 4 is supplied to at least one of the motor 5 and the battery 6.

[0061] When the risk of engine stall or sinking of the rice transplanter 100R in the field due to an increase in the running load is detected, power generation by the motor generator 4 is stopped, and the output of the engine 3 used for power generation is used as driving force for traveling. Then, when it is determined that only stopping power generation is not sufficient to deal with the increase in the running load, the motor generator 4 is made to function as a motor to assist the output of the engine 3, and the increase in the running load is covered. By driving the motor generator 4 as a motor to assist the output of the engine 3, it is possible to prevent the rice transplanter 100R from sinking in places in the field where the running load is high (such as mud), and to allow the rice transplanter 100R to escape by itself if it has sunk.

[0062] In addition, if the rice transplanter 100R is equipped with a switching mechanism 9 that switches the power transmission state between the motor generator 4 and the motor 5 between a connected state and a disconnected state, the rice transplanter 100R may be operated as follows.

[0063] For example, if a malfunction (breakdown, etc.) occurs in the electric-related system that drives the planting device 2A, the switching mechanism 9 may be connected as an emergency operation. By doing so, the planting device 2A can be driven using the output of the engine 3 instead of the output of the motor 5.

[0064] Also, for example, when it is determined that the increase in the running load cannot be sufficiently handled by simply having the motor generator 4 function as a motor to assist the output of the engine 3, the switching mechanism 9 may be brought into the connected state. In this way, the output of the motor generator 4 (and ultimately the engine 3) can be assisted by the driving force of the motor 5 to handle the increase in the running load. Note that, when the driving force of the motor 5 is used to assist the output of the engine 3, it is preferable to stop driving the planting device 2A. Alternatively, it is preferable that the driving force of the motor 5 is used to assist the output of the engine 3 when planting work is not being performed by the planting device 2A.

[0065] <3. Field machine control system> Fig. 6 is a diagram showing a schematic configuration of a control system in the field work machine 100 according to an embodiment of the present invention. As shown in Fig. 6, the field work machine 100 includes a control device 41, a storage device 42, and an operation device 43.

[0066] The control device 41 includes an arithmetic circuit, a memory, and an input / output unit. The arithmetic circuit is, for example, a processor or a microprocessor. The memory may be the storage device 42, or may be a device separate from the storage device 42. The functions of the control device 41 are realized, for example, by the arithmetic circuit executing arithmetic processing according to a program stored in the memory or the like. The control device 41 is disposed in an appropriate position on the traveling vehicle body 1 (preferably the vehicle frame 11).

[0067] The control device 41 may be configured as one piece of hardware, or may be configured as multiple pieces of hardware that can communicate with each other. The functions of the control device 41 may be realized by the arithmetic circuit executing arithmetic processing according to a program as described above, that is, by software, but may also be realized by other methods. At least some of the functions of the control device 41 may be realized using, for example, an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). That is, at least some of the functions of the control device 41 may be realized by hardware using a dedicated IC or the like. Also, at least some of the functions of the control device 41 may be realized by using both software and hardware.

[0068] The storage device 42 is a main storage device such as a Read Only Memory (ROM) and a Random Access Memory (RAM). The storage device 42 may further include an auxiliary storage device such as a Hard Disk Drive (HDD) or a Solid State Drive (SSD). The storage device 42 stores various programs, data, and the like. For example, the storage device 42 stores a load calculation map 42a, the details of which will be described later. The storage device 42 is disposed in an appropriate position of the traveling machine body 1 (preferably the machine body frame 11).

[0069] The operation device 43 enables the operator of the field work machine 100 to input control commands to the control device 41. The operation device 43 may be composed of a single device, or may be composed of multiple devices. The operation device 43 may include various levers, pedals, buttons, etc., arranged in the driver's seat 20 (see FIG. 3, etc.) described above.

[0070] As shown in Fig. 6, the control device 41 controls an engine ECU (Electronic Control Unit) 1a. Under the control of the control device 41, the engine ECU 1a performs electronic control for, for example, injecting fuel into the engine at a good timing and in an optimal amount. The control device 41 acquires various information related to the engine from the engine ECU 1a. The engine ECU 1a is disposed at an appropriate position in the traveling machine body 1 (preferably the machine body frame 11). The control device 41 may also have the functions of the engine ECU 1a, in which case the engine ECU 1a is not necessary.

[0071] Furthermore, the control device 41 controls the first inverter 7a and the second inverter 7b. That is, the first inverter 7a controls the operation of the motor generator 4 under the control of the control device 41. The second inverter 7b controls the operation of the motor 5 under the control of the control device 41. The control device 41 acquires information related to the motor generator 4 and the motor 5 via the first inverter 7a and the second inverter 7b.

[0072] The control device 41 also controls a battery management system (BMS) 6a. The BMS 6a is configured as a control circuit, and monitors and controls the charging and discharging of the battery 6 under the control of the control device 41. The control device 41 acquires information related to the battery via the BMS 6a. The BMS 6a is disposed at an appropriate position in the traveling machine body 1 (preferably the machine body frame 11).

[0073] The control device 41 also controls the operation of a relay 8a included in the junction box 8 (see FIG. 1). In this embodiment, the control device 41 controls a plurality of relays 8a.

[0074] Fig. 7 is a flow chart showing an example of the control operation of the motor generator 4 by the control device 41. Note that the operation shown in Fig. 7 is executed when the field work machine 100 is traveling.

[0075] In step S1, the control device 41 acquires a running load, which is a load applied to the engine 3 during running. As described above, the running load can be acquired based on control information for the engine 3 and information detected by various sensors. An example of a method for acquiring the running load will be described later. Note that an index value of the running load may be acquired instead of the running load itself. As will be understood from the process contents described below, in the field work machine 100, the operating state of the motor generator 4 is changed according to the running load, which is a load applied to the engine 3 during running, or an index value of the running load. This makes it possible to operate the motor generator 4 appropriately according to the situation, and to improve the running state of the field work machine 100 and the energy efficiency. Once the running load has been acquired, the process proceeds to the next step S2.

[0076] In step S2, the control device 41 determines whether the acquired road load is smaller than a first threshold value set in advance. If the road load is smaller than the first threshold value (Yes in step S2), the process proceeds to the next step S3. If the road load is equal to or greater than the first threshold value (No in step S2), the process proceeds to step S5.

[0077] In step S3, the control device 41 issues a power generation command to the first inverter 7a. This is because it is estimated from the relationship between the traveling load and the first threshold that the load on the engine 3 is not large and there is a margin for using the output of the engine 3 for power generation. The first threshold is set so that such an estimation can be made. The control operation of the first inverter 7a in response to the power generation command causes the motor generator 4 to rotate by the driving force from the engine 3 and generate power. For example, when the working device 2 is performing work, the generated power is supplied to the second inverter 7b and used to drive the motor 5. In addition, when the power supply to the motor 5 is unnecessary because, for example, the working device 2 is not operating, the generated power is used to charge the battery 6. Note that, when the supply of power to the battery 6 is unnecessary, such as when the battery 6 is fully charged, the power generation command may be released and the power generation function of the motor generator 4 may be stopped. When the control device 41 issues the power generation command, the process proceeds to the next step S4.

[0078] In step S4, the control device 41 determines whether or not there is a reason to end control. Examples of reasons to end control include a case where an operator issues a command to stop driving, or an engine stall occurs. If there is a reason to end control (Yes in step S4), the control flow shown in Fig. 7 ends. If there is no reason to end control (No in step S4), the process returns to step S1, and the processes from step S1 onwards are performed again.

[0079] In step S5, the control device 41 determines whether the road load greater than the first threshold is less than a preset second threshold. The second threshold is greater than the first threshold. If the road load is less than the second threshold (Yes in step S5), the process proceeds to the next step S6. If the road load is equal to or greater than the second threshold (No in step S5), the process proceeds to step S7.

[0080] In step S6, the control device 41 issues a power generation stop command to the first inverter 7a. This is because it is estimated that the load on the engine 3 is relatively large and there is no room to use the output of the engine 3 for power generation, based on the relationship between the running load and the first and second threshold values. The first and second threshold values ​​are set so that such an estimation can be made. The motor generator 4 stops power generation due to the control operation of the first inverter 7a in response to the power generation stop command. When the power generation stop command is issued by the control device 41, the process proceeds to step S4. After this, as described above, if there is a reason to end the control, the control flow shown in FIG. 7 is ended, and if there is no reason to end the control, the process returns to step S1.

[0081] In step S7, the control device 41 issues an assist command to the first inverter 7a. This is because, based on the relationship between the running load and the second threshold, it is estimated that the load on the engine 3 is large, and that a risk such as engine stall may occur. The second threshold is set so that such an estimation can be made. The control operation of the first inverter 7a in response to the assist command causes the motor generator 4 to function as a motor and assist the output of the engine 3. When the assist command is issued, the process proceeds to step S4. Thereafter, as described above, if there is a reason to end the control, the control flow shown in FIG. 7 is ended, and if there is no reason to end the control, the process returns to step S1.

[0082] As can be seen from the above, when the road load or the road load index value becomes equal to or greater than the first threshold value, the motor generator 4 stops generating power. This allows the engine 3 to use the output that was used for generating power for driving. Also, when the road load or the road load index value becomes equal to or greater than a second threshold value that is greater than the first threshold value, the motor generator 4 assists the output of the engine 3. This allows the output of the motor generator 4 to make up for the insufficient output when the output that was used for generating power is used for driving alone.

[0083] As in this embodiment, by gradually switching the operation of the motor generator 4, it is possible to improve the efficiency of energy use and appropriately travel the field work machine 100. However, if it is determined that the load on the engine 3 during travel has increased, the power generation function of the motor generator 4 may be stopped and the motor generator 4 may immediately function as a motor to assist the output of the engine 3.

[0084] 8 is a flowchart illustrating a flow of processing executed by the control device 41 to acquire the traveling load. FIG 8 shows a specific example of the processing of step S1 in FIG 7.

[0085] In step S11, the control device 41 detects the current throttle opening. The throttle opening may be detected, for example, by using a potentiometer that detects the position of a lever that controls the rotation of the engine 3. When the current throttle opening is detected, the process proceeds to the next step S12.

[0086] In step S12, the control device 41 detects the current engine speed. The current engine speed can be obtained from the speed of the motor generator 4, for example. The speed of the motor generator 4 can be detected by a rotation sensor provided in the motor generator 4. The control device 41 can obtain the detection value of the rotation sensor via the first inverter 7a. When the current engine speed is detected, the process proceeds to the next step S13. Note that the process of step S11 and the process of step S12 may be performed in the opposite order, or may be performed in parallel.

[0087] In step S13, the control device 41 reads out the load calculation map 42a from the storage device 42. The load calculation map 42a is a map used to calculate the running load, and in this embodiment, is a map (graph) showing the characteristics of the engine 3. The characteristics of the engine 3 are so-called droop governor characteristics. After the load calculation map 42a is read out, the process proceeds to the next step S14. The process of step S13 may be performed prior to the process of step S11, or may be performed in parallel with the processes of steps S11 and S12.

[0088] In step S14, the control device 41 determines whether or not driving assistance is being performed using the motor generator 4. Whether or not driving assistance is being performed can be determined, for example, from the history of control commands to the motor generator 4. If driving assistance is not being performed (No in step S14), processing proceeds to the next step S15. If driving assistance is being performed (Yes in step S14), processing proceeds to step S16.

[0089] In step S15, the control device 41 calculates the road load using the previously acquired current throttle opening degree, the current engine speed, and the load calculation map 42a. An example of the calculation of the road load will be described with reference to FIG.

[0090] FIG. 9 is a diagram for explaining an example of calculation of a running load using the load calculation map 42a. In this example, the load calculation map 42a is a graph showing engine characteristics. The horizontal axis of the graph shown in FIG. 9 is the rotation speed, and the vertical axis is the torque. In this graph, a straight line is provided that shows the relationship between the rotation speed and the torque for each throttle opening (shown as a percentage in the figure). Also, the dashed line in the graph shows the torque limit value.

[0091] Here, it is assumed that the throttle opening obtained in the process of step S1 is 60%. In this case, a line (a line showing the relationship between rotation speed and torque) with a throttle opening of 60% is used in a graph showing engine characteristics. On this line, the rotation speed X1 at which the torque becomes zero is the current engine target rotation speed. However, due to the existence of a road load, the current engine rotation speed is a rotation speed R1 which is smaller than the engine target rotation speed X1. It is assumed that the rotation speed at which the road load becomes maximum when the throttle opening is 60% is the rotation speed X2 at which the line with the throttle opening of 60% intersects with the torque limit value. Since it can be assumed that the load factor of the road load is 0% when the rotation speed is X1 and 100% when the rotation speed is X2, the current road load (load factor) can be calculated by the following calculation formula (1) using proportional distribution. Running load (load factor)=(X1-R1) / (X1-X2)*100 (1)

[0092] The road load thus obtained is used to control the operation of the motor generator 4 (see FIG. 7 above). Note that instead of obtaining the road load as described above, an index value of the road load may be used, for example, a difference value between the current engine target speed and the actual engine speed may be used as the index value of the road load. Furthermore, the road load may be configured to be notified to the operator in addition to being used for controlling the operation of the motor generator 4. This makes it possible to assist the operator in driving the vehicle when the vehicle is in manual operation.

[0093] In step S16, the control device 41 corrects the current engine speed. This is because the speed of the motor generator 4 obtained by the control device 41 via the first inverter 7a is different from the speed that is actually output by the engine 3, due to the driving assistance provided by the motor generator 4. An example of the correction of the speed will be described with reference to FIG.

[0094] FIG. 10 is a diagram for explaining the rotation speed correction executed in the process shown in FIG. 8. FIG. 10 is a diagram in which a part of FIG. 9 is cut out and enlarged, and elements necessary for explaining the correction are added. In the explanation using FIG. 10, the accelerator opening is assumed to be 60%. Since the engine is assisted by the motor generator 4, the current engine rotation speed R1 obtained in step S12 in FIG. 8 is the rotation speed obtained by adding the rotation speed xa to the rotation speed R2 originally output by the engine 3. For this reason, the current engine rotation speed R1 obtained in step S12 in FIG. 8 needs to be corrected.

[0095] The torque (assist torque Y) output by the motor generator 4 for the purpose of assist is obtained from the first inverter 7a. For this purpose, the rotation speed R2 that the engine 3 should originally be outputting (the corrected rotation speed R2) is obtained by subtracting the rotation speed (in the example shown in FIG. 10, this corresponds to the rotation speed xa) corresponding to the assist torque Y obtained according to the straight line showing the relationship between the rotation speed and torque when the accelerator opening is 60% from the current engine rotation speed R1 obtained in step S12 in FIG. 8.

[0096] Once the corrected rotation speed R2 is obtained, processing proceeds to step S15, and the corrected rotation speed R2 obtained in step S16 can be used to calculate the current driving load (load rate) when driving assistance is being performed according to the following equation (2). Running load (load factor)=(X1-R2) / (X1-X2)*100 (2)

[0097] Next, a modified example of the control operation by the control device 41 will be described. Fig. 11 is a flowchart showing a modified example of the control operation by the control device 41 described in Fig. 7. In Fig. 7, it is assumed that there is no switching mechanism 9 (see Fig. 2) that switches the power transmission state between the motor generator 4 and the motor 5. In Fig. 11, it is assumed that there is a switching mechanism (clutch) 9 controlled by the control device 41.

[0098] The flowchart shown in Fig. 11 is generally similar to the flowchart shown in Fig. 7. However, in the flowchart shown in Fig. 11, processing in step S7A and processing in step S8 are added to the flowchart shown in Fig. 7. The following description focuses on these added parts.

[0099] In this modified example, when the road load is equal to or greater than the second threshold (No in step S5), the process proceeds to step S7A instead of step S7. In step S7A, the control device 41 determines whether the road load greater than the second threshold is less than a preset third threshold. The third threshold is greater than the second threshold. When the road load is less than the third threshold (Yes in step S7A), the process proceeds to step S7. In step S7, as in the case of FIG. 7, an assist command is issued to the motor generator 4, whereby the motor generator 4 assists the output of the engine 3. When the road load is equal to or greater than the third threshold (No in step S7A), the process proceeds to step S8.

[0100] In step S8, the control device 41 issues an assist command to the first inverter 7a and the second inverter 7b. This is because, based on the relationship between the running load and the third threshold value, it is estimated that the load on the engine 3 is very large, and that the engine stall or other dangers may occur if the motor generator 4 is only assisted. The third threshold value is set so that such an estimation can be made. The motor generator 4 assists the output of the engine 3 by the control operation of the first inverter 7a in response to the assist command. Also, the motor 5 assists the output of the motor generator 4 by the control operation of the second inverter 7b in response to the assist command. That is, the output of the engine 3 is assisted by both the motor generator 4 and the motor 5. When the output of the motor generator 4 is assisted by the motor 5, the switching mechanism 9 is in a connected state. After this, the process proceeds to step S4, and as in the case of FIG. 7, if there is a reason for terminating the control, the control flow shown in FIG. 11 is terminated, and if there is no reason for terminating the control, the process returns to step S1.

[0101] Note that when an assist command is issued to the second inverter 7b, if the working device 2 is being driven, the driving of the working device 2 is stopped. Alternatively, a configuration may be adopted in which an assist command is issued to the second inverter 7b only when the driving of the working device 2 is stopped. Furthermore, after the assist of the output of the engine 3 by the motor 5 is started by the processing of step S8, if the processing of steps S1 and onward is performed and it is determined that the traveling load is smaller than the third threshold, the assist by the motor 5 is stopped. In this case, the driving of the working device 2 using the motor 5 may be started as appropriate.

[0102] As can be seen from the above, in this modified example, when the running load or the index value of the running load becomes equal to or greater than the third threshold value that is greater than the second threshold value, the switching mechanism 9 is brought into a connected state, and the motor 5 assists the output of the motor generator 4 without supplying driving force to the work implement 2. This makes it possible to increase the force that assists the output of the engine 3. As a result, even if the field work implement 100 becomes stuck in mud in the field and is likely to sink, for example, it can obtain a large assist force and avoid sinking.

[0103] <4. Engine rotation control> Next, a detailed example of rotation control of the engine 3 that is provided so as to be assisted by the motor generator 4 will be described. The rotation control of the engine 3 described below may be applied to a system in which a motor is used instead of the motor generator 4. The engine 3 may also be configured to supply power to the working implement 2 via a PTO (power take-off) shaft. In this case, the field working implement 100 may not need to be equipped with the second rotating electric machine (motor) 5.

[0104] Fig. 12 is a block diagram showing a schematic configuration of a system for controlling the rotation of the engine 3, which is provided in the field work machine 100. Note that solid arrows in Fig. 12 indicate the flow of control, and hollow arrows indicate the flow of power.

[0105] 12, the field work machine 100 is equipped with a continuously variable transmission 61 that changes the speed of power from the engine 3 and outputs it to the traveling device 12. The continuously variable transmission 61 may be, for example, a hydraulic transmission, and more specifically, may be an HST (Hydraulic Static Transmission) or an HMT (Hydro Mechanical Transmission). Furthermore, the continuously variable transmission 61 may be a mechanical transmission instead of a hydraulic transmission.

[0106] In detail, the power changed in speed by the continuously variable transmission 61 is transmitted to the traveling device 12 via power transmission elements contained in the transmission case 62. A traveling speed change gear mechanism, a differential mechanism, etc. are contained in the transmission case 62. Note that in the case where the power of the engine 3 is supplied to the working device 2 via the PTO shaft, the transmission case 62 may contain a PTO speed change mechanism for appropriately changing the rotation speed of the PTO shaft.

[0107] 12, the control device 41 includes, as its functions, an assist control unit 41a, an accelerator control unit 41b, and a gear shift control unit 41c. As described above, the functions of these functional units 41a to 41c may be realized by software or hardware. Furthermore, the functions of these functional units 41a to 41c may be realized by a combination of software and hardware.

[0108] The assist control unit 41a controls the motor generator 4 via the first inverter 7a, and changes the state of assist of the output of the engine 3 by the motor generator 4. The accelerator control unit 41b controls the engine 3 via the engine ECU 1a, and increases or decreases the rotation speed of the engine 3. The transmission control unit 41c controls the continuously variable transmission 61, and changes the traveling speed (vehicle speed) of the field work machine 100. In other words, the field work machine 100 includes a control device 41 that controls the engine 3, the motor generator (first rotating electric machine) 4, and the continuously variable transmission 61.

[0109] In this embodiment, the gear shift control unit 41c calculates the target rotation speed of the engine 3 according to the amount of operation of a gear shift operating device (not shown) such as a gear shift pedal. The gear shift operating device may be included in the above-mentioned operation device 43 (see FIG. 6). The accelerator control unit 41b controls the rotation speed of the engine 3 so that it becomes the target rotation speed calculated by the gear shift control unit 41c. With this configuration, the operator of the field work machine 100 can obtain an appropriate rotation speed of the engine 3 corresponding to the gear shift operating device simply by operating it.

[0110] In the field work machine 100 of this embodiment, when a discrepancy occurs between the target rotation speed and the actual rotation speed of the engine 3 due to the load when traveling in the field, etc., the motor generator 4 assists the output of the engine 3 (traveling assist). The rotation control of the engine 3 taking into account this traveling assist will be described below using a specific example. Figs. 13 and 14 are diagrams for explaining the rotation control of the engine 3 in the field work machine 100 equipped with a traveling assist function. Fig. 13 is a diagram showing an example in which the rotation of the engine 3 is restored by the traveling assist. Fig. 14 is a diagram showing an example in which the rotation of the engine 3 is not restored by the traveling assist.

[0111] 13 and 14, the "target rotation speed" is the target rotation speed of the engine 3. As described above, the target rotation speed of the engine 3 is determined according to the amount of operation of the speed change operating device. In addition, in FIG. 13 and FIG. 14, the "actual rotation speed" is the actual rotation speed of the engine 3, and the control device 41 can appropriately acquire the actual rotation speed of the engine 3 from, for example, the engine ECU 1a or the like. In addition, in FIG. 13 and FIG. 14, the "speed ratio" is the speed transmission ratio of the continuously variable transmission 61, and may be replaced with the traveling speed (vehicle speed) of the field work machine 100. In addition, in FIG. 13 and FIG. 14, the "assist torque" indicates the magnitude of the torque when the motor generator 4 assists the output of the engine 3 (assist by the motor function: traveling assist). In addition, the rotation speed difference between the target rotation speed and the actual rotation speed of the engine 3 can be said to be an index value of the traveling load.

[0112] First, a case where the rotation of the engine 3 is restored by the driving assist will be described with reference to Fig. 13. In the example shown in Fig. 13, at time t1, the driving load increases, and the actual rotation speed of the engine 3 starts to deviate from the target rotation speed in a decreasing direction. Then, at time t2, the actual rotation speed of the engine 3 deviates from the target rotation speed by a predetermined rotation speed difference (first threshold value TH1). At the time t1, the driving assist is not being performed, and the assist torque is zero.

[0113] At time t2, driving assistance is started using the motor generator 4. That is, the control device 41 detects the difference in rotation speed between the target rotation speed and the actual rotation speed of the engine 3, and when the difference in rotation speed becomes equal to or greater than a predetermined rotation speed difference (first threshold value TH1 in this example), causes the motor generator (first rotating electric machine) 4 to assist the output of the engine 3. When the load on the engine 3 increases and the rotation speed of the engine 3 decreases, the driving assistance is started automatically, so that engine stall can be avoided without the operator having to perform any particular operation.

[0114] The magnitude of the assist torque during driving assistance is preferably determined according to the magnitude of the difference between the target rotation speed and the actual rotation speed of the engine 3. However, the magnitude of the assist torque during driving assistance may be a predetermined amount. As described below, it is preferable that the magnitude of the assist torque when driving assistance is performed is increased in stages.

[0115] In addition, in this embodiment, the target rotation speed of the engine 3 is increased at time t2. That is, when the rotation speed difference between the target rotation speed and the actual rotation speed of the engine 3 becomes equal to or greater than a predetermined rotation speed difference, the control device 41 increases the target rotation speed of the engine 3 to execute the traveling assist. By configuring in this way, it is possible to increase the possibility that the actual rotation speed of the engine 3 increases. Also, by configuring to increase the target rotation speed of the engine 3 to the maximum, it is possible to detect the reduction amount of the actual rotation speed relative to the target rotation speed (in other words, the traveling load) with good reproducibility. As a result, it is possible to appropriately determine the assist torque that is determined according to the magnitude of the rotation speed difference between the target rotation speed and the actual rotation speed of the engine 3. In this sense, in detail, when the rotation speed difference between the target rotation speed and the actual rotation speed of the engine 3 becomes equal to or greater than a predetermined rotation speed difference, it is preferable to increase the target rotation speed of the engine 3 and then start the traveling assist.

[0116] In the example shown in FIG. 13, the speed ratio of the continuously variable transmission 61 is reduced at time t3 when a predetermined time T1 has elapsed since the start of the traveling assist (which can be said to be the timing of increasing the assist torque). The reduction in the speed ratio of the continuously variable transmission 61 reduces the traveling speed of the field work machine 100. In other words, when the rotation speed difference between the target rotation speed and the actual rotation speed of the engine 3 becomes equal to or greater than a predetermined rotation speed difference, the control device 41 executes the reduction in the traveling speed by changing the speed ratio of the continuously variable transmission 61. With this configuration, the traveling load itself can be reduced, and it is possible to prevent an excessive torque load from being imposed on the motor generator 4 that performs the traveling assist. Furthermore, by reducing the traveling load itself, it is possible to increase the possibility that the discrepancy between the target rotation speed and the actual rotation speed will be eliminated.

[0117] In the present embodiment, as a preferred configuration, the control device 41 changes the speed ratio of the continuously variable transmission 61 after the start of the assist (traveling assist). The start of the traveling assist and the change (reduction) of the speed ratio may be performed at the same time. However, in a configuration in which the speed ratio of the continuously variable transmission 61 is changed after the traveling assist is started as in the present embodiment, it is possible not to change the speed ratio of the continuously variable transmission 61 when the discrepancy between the target rotation speed and the actual rotation speed of the engine 3 is eliminated by the traveling assist alone. In other words, it is possible to avoid unnecessarily reducing the traveling speed of the field work machine 100.

[0118] The amount of change in the speed ratio of the continuously variable transmission 61 may be determined, for example, according to the magnitude of the difference in rotation speed between the target rotation speed and the actual rotation speed of the engine 3, or may be a predetermined amount.

[0119] It is preferable that the speed ratio of the continuously variable transmission 61 is changed stepwise, as in the case of the assist torque. In the example shown in FIG. 13, the control device 41 executes the travel assist and the change of the speed ratio stepwise. Even if the assist torque during the travel assist or the speed of the field work machine 100 is only slightly reduced, the deviation between the target rotation speed and the actual rotation speed of the engine 3 may be eliminated. For this reason, by executing the travel assist stepwise, the load on the motor generator 4 during the travel assist can be reduced as much as possible, and the power consumption of the battery 6 can be reduced as much as possible. In addition, by executing the change of the speed ratio of the continuously variable transmission 61 stepwise, it is possible to prevent the speed of the field work machine 100 from decreasing as much as possible. In addition, during field work, where the travel load is easily changed and it is difficult to determine how much the speed ratio should be reduced, the speed ratio can be reduced while observing the change in the travel load condition.

[0120] 13, in detail, the assist torque is increased a second time at a timing (time t4) when a time T2 has elapsed since the immediately preceding timing (time t2) of the increase in assist torque. Also, the speed ratio of the continuously variable transmission 61 is reduced a second time at a timing (time t5) when a time T1 has elapsed since the immediately preceding timing (time t4) of the increase in assist torque. The timing at which the assist torque is increased or the speed ratio of the continuously variable transmission 61 is reduced may be determined arbitrarily.

[0121] In the example shown in FIG. 13, after the speed ratio of the continuously variable transmission 61 is reduced for the second time (specifically, at time t6), the rotation speed difference between the target rotation speed and the actual rotation speed of the engine 3 becomes equal to or less than a predetermined rotation speed difference (second threshold value TH2 in this example). As a result, it is determined that the deviation between the target rotation speed and the actual rotation speed of the engine 3 caused by an increase in the traveling load has been eliminated, and the traveling assist is gradually terminated. Terminating the traveling assist can reduce consumption of the electric power of the battery 6. Furthermore, terminating the traveling assist can prevent excessive torque from being applied to the traveling transmission system.

[0122] Note that the driving assistance may be abruptly stopped (assist torque is set to zero) when it is determined that the difference between the target rotation speed and the actual rotation speed of the engine 3 has been eliminated. However, by gradually ending the driving assistance as in this embodiment, it is possible to reduce the possibility of the engine speed suddenly dropping and causing an engine stall.

[0123] In the example shown in FIG. 13, after the driving assistance is ended (specifically, at time t7), the target rotation speed of the engine 3 is returned to the original target rotation speed. The original target rotation speed is the target rotation speed before the target rotation speed was increased the previous time (see time t2). The timing at which the target rotation speed of the engine 3 is returned to the original target rotation speed may be the same as the timing at which the driving assistance is ended. However, if the target rotation speed of the engine 3 is configured to be returned to the original target rotation speed after the driving assistance is ended as in this embodiment, it is possible to reduce the possibility of the rotation speed of the engine 3 suddenly decreasing and causing an engine stall.

[0124] In the example shown in FIG. 13, after the target rotation speed of the engine 3 is returned to the original target rotation speed (specifically, at time t8), the speed ratio of the continuously variable transmission 61 is returned to the original speed ratio. The original speed ratio is the speed ratio before the speed ratio of the continuously variable transmission 61 is reduced for the first time (see time t3). The timing of returning the speed ratio of the continuously variable transmission 61 to the original speed ratio may be the same as the timing of ending the travel assistance. However, as in this embodiment, by setting the timing after the travel assistance is ended and the target rotation speed of the engine 3 is returned to the original target rotation speed, the speed ratio of the continuously variable transmission 61 can be increased after confirming that the rotation speed of the engine 3 is stable at the target rotation speed. This makes it possible to avoid the occurrence of a situation in which the load applied to the engine 3 suddenly increases at a time when the rotation speed of the engine 3 is not stable at the target rotation speed, causing the engine to stall.

[0125] 14, similarly to FIG 13, at the timing (time t2) when it is determined that the actual rotation speed of the engine 3 has deviated from the target rotation speed, the driving assistance is started and the target rotation speed of the engine 3 is increased. After that, the speed ratio of the continuously variable transmission 61 is reduced, and the assist torque is increased and the speed ratio is reduced in a stepwise manner. However, in the example shown in FIG 14, unlike the example in FIG 13, the deviation between the target rotation speed and the actual rotation speed of the engine 3 remains unresolved despite these measures.

[0126] In the example shown in Fig. 14, when it is determined that the discrepancy between the target rotation speed and the actual rotation speed of the engine 3 has not been eliminated even after a predetermined time (time T3) has elapsed since the start of the traveling assistance, the control device 41 stops the traveling assistance and stops traveling by changing the speed ratio of the continuously variable transmission 61. With this configuration, it is possible to prevent the field work machine 100 from continuing to be subjected to a significant traveling load. It is also possible to prevent excessive load from being applied to the motor generator 4. This makes it possible to prevent the occurrence of problems such as damage to the field work machine 100.

[0127] In the example shown in Fig. 14, in addition to stopping the travel assistance and stopping the travel, a process is also performed to return the target rotation speed of the engine 3 to the original target rotation speed (see time t9). This makes it possible to suppress unnecessary fuel consumption and noise of the engine 3. Furthermore, when the travel assistance and the travel stop are performed, it is preferable to notify the operator of this. This makes it possible to prevent the operator from mistakenly determining that the travel has stopped due to a malfunction of the field work machine 100.

[0128] 14, the traveling assist is stopped, etc., when the discrepancy between the target rotation speed and the actual rotation speed of the engine 3 is not resolved even after a predetermined time has elapsed since the start of the assist, but this is merely an example. Instead of the predetermined time having elapsed, it may be when the field work machine 100 has traveled a predetermined distance. As another embodiment, the traveling assist may be stopped, etc., when the rotation speed difference between the target rotation speed and the actual rotation speed of the engine 3 becomes equal to or greater than a third threshold value TH3 that is greater than the first threshold value TH1.

[0129] Figures 15A and 15B are flow charts illustrating the flow of rotation control of the engine 3 executed by the control device 41. Note that Figures 15A and 15B are merely divided into two diagrams for convenience due to the large number of steps constituting a series of flows, and are actually shown as one diagram. The flows shown in Figures 15A and 15B start when the field work machine 100 starts traveling.

[0130] In step S21, the control device 41 (the gear shift control section 41c) determines, in accordance with the amount of operation of the gear shift operating device, a target rotation speed of the engine 3. Once the target rotation speed of the engine 3 has been determined, the process proceeds to the next step S22.

[0131] In step S22, the control device 41 (accelerator control unit 41b) determines the accelerator opening so as to achieve the determined target rotation speed of the engine 3. As a result, the engine 3 starts to drive at the target rotation speed. Once the accelerator opening is determined, the process proceeds to the next step S23.

[0132] In step S23, the control device 41 (accelerator control section 41b) monitors whether the rotation speed difference between the target rotation speed and the actual rotation speed of the engine 3 is equal to or greater than a predetermined rotation speed difference (first threshold value TH1 in the examples shown in Figs. 13 and 14). If the rotation speed difference between the target rotation speed and the actual rotation speed of the engine 3 is equal to or greater than the predetermined rotation speed difference (Yes in step S23), the process proceeds to the next step S24. If the rotation speed difference between the target rotation speed and the actual rotation speed of the engine 3 is smaller than the predetermined rotation speed difference (No in step S23), the monitoring in step S23 continues.

[0133] In step S24, the control device 41 (accelerator control unit 41b) determines an increase in the target rotation speed (original target rotation speed) previously determined by the gear shift control unit 41c, and controls the engine 3 so that the engine 3 operates at the increased target rotation speed. The increased target rotation speed is set to, for example, the maximum rotation speed (maximum rotation speed) that can be reached by the engine 3. Note that if the target rotation speed of the engine 3 is already the maximum rotation speed, the process of step S24 may be skipped. Once the target rotation speed of the engine 3 has been increased, the process proceeds to the next step S25.

[0134] In step S25, the control device 41 (assist control section 41a) causes the motor generator 4 to start a driving assist that assists the output of the engine 3. The driving assist is preferably started almost simultaneously with the previous increase in the target rotation speed of the engine 3. Once the driving assist is started, the process proceeds to the next step S26.

[0135] In step S26, the control device 41 (transmission control section 41c) performs processing to change the speed ratio of the continuously variable transmission 61 (speed ratio change processing) so as to reduce the traveling speed of the field work machine 100. This reduces the speed of the field work machine 100. The speed ratio change processing is preferably performed after a predetermined time has elapsed since the start of the traveling assistance (time T1 in the examples shown in Figs. 13 and 14). Once the speed ratio change processing has been performed, processing proceeds to the next step S27.

[0136] In this example, the speed ratio change process is always performed after the start of the driving assistance, but if the difference between the target rotation speed and the actual rotation speed of the engine 3 is immediately eliminated by the start of the driving assistance, the speed ratio change process does not have to be performed. In this case, the driving assistance may be ended at any timing, or the target rotation speed of the engine 3 may be returned to the original target rotation speed.

[0137] In step S27, the control device 41 (assist control section 41a) monitors whether a predetermined time (time T2 in the examples shown in Figs. 13 and 14) has elapsed since the start of the driving assistance. If the predetermined time has elapsed (Yes in step S27), the process proceeds to the next step S28. If the predetermined time has not elapsed (No in step S27), the monitoring in step S27 continues.

[0138] In this example, the stepwise assist torque increase process and the speed ratio change process are always performed a predetermined number of times. However, if the deviation between the target rotation speed and the actual rotation speed of the engine 3 is eliminated in the process of step S26 (speed ratio change process), the process of step S27 does not need to be executed. In this case, the driving assist may be ended at any timing, the target rotation speed of the engine 3 may be returned to the original target rotation speed, and the speed ratio of the continuously variable transmission 61 may be returned to the original speed ratio. The contents described here are also applicable to the case where the deviation between the target rotation speed and the actual rotation speed of the engine 3 is eliminated by increasing the assist torque in step S28 described below.

[0139] In step S28, the control device 41 (assist control section 41a) commands the motor generator 4 to increase the assist torque. This causes the motor generator 4 to increase the assist torque. When the command to increase the assist torque is issued, the process proceeds to the next step S29.

[0140] In step S29, the control device 41 (transmission control section 41c) performs processing to cause the continuously variable transmission 61 to change the speed ratio (speed ratio change processing) so that the traveling speed of the field work machine 100 is further reduced. This further reduces the speed of the field work machine 100. The speed ratio change processing is preferably executed after a predetermined time (time T1 in the examples shown in Figures 13 and 14) has elapsed since the previous timing of the increase in assist torque. Once the speed ratio change processing has been executed, the process proceeds to the next step S30.

[0141] In this example, the assist and the change in the speed ratio are performed in two stages, but they may be performed in three stages or more.

[0142] In step S30, the control device 41 (assist control section 41a) judges whether the discrepancy between the target rotation speed and the actual rotation speed of the engine 3 has been eliminated. In detail, whether the discrepancy between the target rotation speed and the actual rotation speed of the engine 3 has been eliminated is judged based on whether the difference between the two rotation speeds is equal to or less than a predetermined threshold (a second threshold TH2 in the example shown in FIG. 13). If the difference between the two rotation speeds is equal to or less than the predetermined threshold, it is judged that the discrepancy between the two has been eliminated (Yes in step S30), and the process proceeds to the next step S31. If the difference between the two rotation speeds is greater than the predetermined threshold, it is judged that the discrepancy between the two has not been eliminated (No in step S30), and the process proceeds to step S35.

[0143] In step S31, the control device 41 (assist control unit 41a) determines whether a predetermined time has elapsed since the discrepancy between the target rotation speed and the actual rotation speed of the engine 3 was eliminated. The predetermined time can be determined arbitrarily. If the predetermined time has elapsed (Yes in step S31), the process proceeds to the next step S32. If the predetermined time has not elapsed (No in step S31), the process returns to step S30.

[0144] In step S32, the control device 41 (assist control section 41a) controls the motor generator 4 to gradually end the driving assistance. In the example shown in FIG. 13, the driving assistance end process is immediately started when the deviation between the target rotation speed and the actual rotation speed of the engine 3 is eliminated. In contrast, in the case of the configuration in which the driving assistance is ended some time after the deviation is eliminated as in this example, the driving assistance can be ended in a state in which the rotation speed of the engine 3 is stable at the target rotation speed. For this reason, the probability of engine stall can be reduced compared to when the driving assistance end process is started at a time when the rotation speed of the engine 3 may be unstable. When the driving assistance end process is performed, the process proceeds to the next step S33.

[0145] In step S33, the control device 41 (accelerator control section 41b) returns the target rotation speed of the engine 3 to the original target rotation speed. After the process of returning to the original target rotation speed is performed, the process proceeds to the next step S34.

[0146] In step S34, the control device 41 (transmission control section 41c) performs processing to return the speed ratio of the continuously variable transmission 61 to the original speed ratio so that the traveling speed of the field work machine 100 returns to the original traveling speed. When the speed ratio of the continuously variable transmission 61 is returned to the original speed ratio, the processing shown in Figures 15A and 15B is temporarily ended. Thereafter, the processing shown in Figures 15A and 15B is repeated as necessary.

[0147] In step S35, the control device 41 (assist control section 41a) determines whether the deviation between the target rotation speed and the actual rotation speed of the engine 3 continues for a predetermined time. The predetermined time can be determined arbitrarily. If the deviation has continued for the predetermined time (Yes in step S35), the process proceeds to the next step S36. If the deviation has not continued for the predetermined time (No in step S35), the process returns to step S30.

[0148] In step S36, the control device 41 (assist control section 41a) ends the traveling assistance using the motor generator 4. The control device 41 (transmission control section 41c) also changes the speed ratio of the continuously variable transmission 61 so that the traveling of the field work machine 100 stops (the traveling speed becomes zero). At this time, it is preferable that the control device 41 (accelerator control section 41b) performs processing to return the target rotation speed of the engine 3 to the original target rotation speed. When the processing of step S36 is completed, the process proceeds to the next step S37.

[0149] In step S37, the control device 41 performs processing to notify the operator that the field work machine 100 has been intentionally stopped from traveling. In response to this notification processing, a notification is issued by a notification unit provided in the field work machine 100 or the portable operation terminal that operates the field work machine 100. This enables the operator to know the reason why the field work machine 100 has stopped traveling. The notification unit is, for example, a display device or an audio output device.

[0150] In this example, when it is detected that the deviation between the target rotation speed and the actual rotation speed of the engine 3 continues for a predetermined time, the vehicle is immediately stopped in response to the result of the detection. However, this configuration is merely an example. When the deviation continues for a predetermined time, for example, the vehicle may be configured to once terminate the driving assistance, and then to repeat the operation of determining whether the deviation continues for a predetermined time after the driving assistance is resumed. Then, when the number of repetitions reaches a predetermined number, the vehicle may be stopped.

[0151] 16 is a block diagram showing a modified example of a system that controls the rotation of the engine 3. The system of the modified example differs in that the control device 41 has a differential lock control section 41d as one of its functions. Also, in this modified example, a transmission case 62 is provided with a differential lock section 62a that stops differential driving of a differential mechanism (not shown) that enables differential movement of the left and right wheels 12a, 12b included in the traveling device 12. In other words, the field work machine 100 is equipped with the differential lock section 62a.

[0152] The differential lock control unit 41d (control device 41) controls the differential lock unit 62a to stop the differential drive in accordance with the difference between the target rotation speed and the actual rotation speed of the engine 3. When the running load increases, the difference between the target rotation speed and the actual rotation speed of the engine 3 increases. For this reason, according to the configuration of this modified example, when the running load increases, it is possible to stop the differential drive.

[0153] In the field work machine 100, when the traveling load increases, the differential mechanism may cause the driving force to be transmitted unintentionally to the left and right wheels unequally. For this reason, by configuring the differential drive to be stopped when the rotation speed difference between the target rotation speed and the actual rotation speed of the engine 3 becomes equal to or greater than a predetermined rotation speed difference, it is possible to prevent differential drive from being performed unintentionally due to an increase in the traveling load. In other words, when the traveling load increases, the differential drive can be stopped and the driving force can be distributed evenly to the left and right wheels.

[0154] The above-mentioned predetermined rotation speed difference when determining whether or not to stop the differential drive may be the same as the predetermined rotation speed difference (first threshold value TH1 in FIG. 13) used to determine whether or not to start the driving assistance, but may also be different.

[0155] Furthermore, the timing for stopping the differential drive may be any timing relative to the timing for increasing the target rotation speed of the engine 3, the timing for starting the traveling assist, and the timing for changing the speed ratio of the continuously variable transmission 61. For example, the timing for stopping the differential drive may be the same as the timing for starting the traveling assist, or may be between the timings for increasing the assist torque that is increased stepwise. Furthermore, it is preferable that the timing for stopping the differential drive is changeable, and may be configured so that it can be set arbitrarily by the operator.

[0156] In addition, it is preferable that the stop of the differential drive that has been performed in response to an increase in the traveling load is released as the traveling load is reduced. In particular, when it is determined that the deviation between the target rotation speed and the actual rotation speed of the engine has been eliminated, the differential lock control unit 41d preferably controls the differential lock unit 62a to release the stop of the differential drive. Whether or not the deviation between the target rotation speed and the actual rotation speed of the engine has been eliminated may be determined based on whether or not the difference between the rotation speeds is equal to or smaller than a predetermined threshold value (e.g., the second threshold value TH2 in FIG. 13). By releasing the stop of the differential drive in response to a reduction in the traveling load, it is possible to avoid problems such as the turning radius of the field work machine 100 becoming too large, for example.

[0157] <5. Power generation control> Next, a detailed example of control of power generation using the motor generator 4 will be described. In the following description, a control device 41 provided in the field work machine 100 controls the motor generator 4. The motor generator (first rotating electric machine) 4 supplies electric power to the battery 6 by generating power using the driving force of the engine (prime mover) 3. These details can be understood from the above description, so detailed description will be omitted.

[0158] In the field work machine 100 of this embodiment, the motor generator 4 can be used as a generator at all times, except when it is used as a motor to assist the output of the engine 3. However, in the field work machine 100, it is preferable that the power of the engine 3 is used as much as possible to drive the traveling device 12 while the machine is traveling in a field. This is because if the proportion of the power of the engine 3 used for generating electricity using the motor generator 4 increases too much, the output of the engine 3 cannot be supplied sufficiently as power for traveling when the traveling load increases, which may cause the engine to stall.

[0159] On the other hand, if power generation using the motor generator 4 is not performed, the remaining capacity of the battery 6 may become too low in the field. If the remaining capacity of the battery 6 becomes too low, it may become impossible to drive the working implement 2 using the motor 5, or it may become impossible to assist the engine 3 with the motor generator 4. For this reason, it is desirable to generate power using the motor generator 4 to the extent possible even while traveling in the field.

[0160] The power generation control of the motor generator 4 in this embodiment has been devised in consideration of the above points. To explain the gist, the control device 41 changes the setting of the power generation amount of the motor generator 4 based on the traveling state of the traveling body 1 equipped in the field work machine 100. In this configuration, it is possible to reduce the power generation amount of the motor generator 4 when the state is such that more power should be allocated for traveling, and to increase the power generation amount of the motor generator 4 when such a state is not met. In other words, when there is a risk of a large traveling load, it is possible to reduce the power generation amount of the motor generator 4. As a result, it is possible to avoid the occurrence of a situation in which the output of the engine 3 cannot be sufficiently supplied as power for traveling due to power generation, causing the engine to stall.

[0161] To explain in more detail, when the traveling load is not large, in principle, the motor generator 4 supplies power to the battery 6 by generating electricity using the driving force of the engine 3 while the traveling body 1 is traveling and while it is stopped. Therefore, even while the traveling body 1 is traveling, it is possible to minimize the decrease in the charge capacity of the battery 6. However, the control device 41 sets the amount of power generated by the motor generator 4 while the traveling body 1 is traveling to be smaller than when the traveling body 1 is stopped. This makes it possible to generate only the minimum amount of power while traveling, and to increase the amount of power generated and charge the battery 6 while traveling is stopped when there is no need to allocate the power of the engine 3 to traveling.

[0162] The stop of the traveling machine body 1 here does not mean a stop for a very short time, but means a state where the traveling machine body 1 is stopped for a certain period of time. Specifically, the stop of the traveling machine body 1 is a stop made to supply materials. The materials are, for example, seedlings, fertilizer, medicine, fuel, etc. Whether or not the stop is for supplying materials can be determined, for example, using the traveling speed and the state of the working device 2. For example, when the traveling speed is zero and the non-use state of the working device 2 continues for a certain period of time, it can be determined that the stop is for supplying materials. When the field work machine 100 is a rice transplanter, for example, when the traveling speed is zero and the float does not touch the ground for a certain period of time, it can be determined that the stop is for supplying materials. In addition, when information on the place to supply materials is stored in advance in the storage device 42 (see FIG. 6), it may be determined whether or not the stop is for supplying materials from the position information of the field work machine 100 in addition to the traveling speed.

[0163] A specific example of power generation control of the motor generator 4 will be described below. Fig. 17 is a diagram showing an example of the operation of the field work machine 100 in a field 70. Here, it is assumed that the field work machine 100 is a rice transplanter. The operation of the field work machine 100 shown in Fig. 17 may be by manual travel or automatic travel.

[0164] As shown in FIG. 17 , the field 70 includes a working area 71 and a headland area 72. The working area 71 is located in the center of the field 70, and is an area for carrying out work (transplanting seedlings). The headland area 72 is located outside the working area 71, and is an area used for carrying out work appropriately in the working area 71. For example, the headland area 72 is used as an area for moving the field work machine 100 that has entered the field 70 to a work start position for transplanting work or the like, an area for turning the field work machine 100, and an area for moving the field work machine 100 to a supply point for materials such as seedlings and fertilizer. The supply point is provided on a ridge 73 adjacent to the headland area 72.

[0165] In Fig. 17, the dashed and dotted lines indicate the route traveled by the field work machine 100. The arrows included in the dashed and dotted lines indicate the traveling direction of the field work machine 100. Also, in Fig. 17, the field work machine 100 shown in broken lines indicates a field work machine that has stopped for replenishment.

[0166] As shown in Fig. 17, the traveling machine body 1 of a field work machine 100 that performs work in a field performs work travel along straight paths 74 and non-work travel along turning paths 75 that connect the straight paths 74. When the field work machine 100 starts work, it repeatedly plants (transplants) seedlings on the straight paths 74 and turns to move to the next straight path 74. The field work machine 100 also periodically stops to replenish seedlings.

[0167] The motor generator 4 generates power at maximum output during a stop to replenish seedlings. This is to charge the battery 6 as much as possible using the power of the engine 3 so that problems such as insufficient power for traveling do not occur even if the motor generator 4 generates power at maximum output during the stop. Also, the motor generator 4 generates the minimum amount of power required during traveling related to work (transplanting and turning). Note that the minimum amount of power required varies depending on the remaining capacity of the battery 6, the work content, the traveling environment, etc. For this reason, in this example, the optimal amount of power generation during traveling (the minimum amount of power required) is obtained using information on the energy balance of the work previously performed.

[0168] More specifically, one cycle is defined as the period from the start of work travel to the completion of stopping for material supply, and each time one cycle is completed, the optimum amount of power generation during travel in the next cycle is calculated using information on the energy balance of that cycle. Note that in this example, when calculating the optimum amount of power generation during travel in the next cycle, only information on the energy balance of the immediately preceding cycle is used, but information on the energy balance of multiple previous cycles may also be used.

[0169] An example of a method for determining the optimal amount of power generation during running in the next cycle based on information on the energy balance of the immediately preceding cycle will be described below. Note that in the first cycle, the optimal amount of power generation during running cannot be determined from information on the previous cycle. For this reason, in the first cycle, a default value or a value according to past performance is used as the optimal amount of power generation during running. It is preferable that multiple types of default values ​​are prepared so that they can be selected according to the current remaining capacity of the battery 6. It is also preferable that the value according to past performance is determined based on the current remaining capacity of the battery 6.

[0170] When calculating the optimal power generation amount during the next cycle of driving, the charging power required during the next cycle of driving is calculated using the following formula (3). Note that the values ​​of each item in formula (3) are absolute values. AA =(BB-CC)+DD-EE×FF...(3) AA: Charging power required for the next cycle [kWh] BB: Capacity to be secured [kWh] CC: Current remaining capacity of battery 6 [kWh] DD: Discharge power in the current cycle [kWh] EE: Power generation during shutdown [kW] FF: Stop time in the current cycle [hr]

[0171] The capacity BB to be secured is a capacity that can secure power for the remaining operations even if an emergency occurs in which driving assistance using the motor generator 4 is performed, and is determined arbitrarily.

[0172] The discharge power DD in the current cycle is the actual value of the current cycle, and is the total value of the power discharged by the motor 5 for the transplanting work in each straight line path 74. For example, if one cycle is "transplant" → "turn" → "transplant" → "turn" → "transplant" → "turn" → "transplant" → "stop", the discharge power DD is the total value of the discharge power for each of the four "transplants".

[0173] The amount of power generated during a stop EE is the amount of power generated when the motor generator 4 is operated at maximum output. The time FF during the stop in the current cycle is the actual value of the time during which the plant was stopped for the supply of materials (seedlings) in the current cycle.

[0174] The optimal power generation amount α [kW] during driving in the next cycle is calculated by the following formula (4) using the charging power AA required during driving in the next cycle calculated by formula (3). α = AA / GG (4) GG: Total time required for implantation and rotation in the current cycle [hr]

[0175] The total time GG required for transplantation and turning in the current cycle is an actual value. For example, if one cycle is "transplantation" → "turning" → "transplantation" → "turning" → "transplantation" → "turning" → "transplantation" → "stop", the total time is the sum of the transplantation time for each of the four "transplantations" and the turning time for each of the four "turning".

[0176] FIG. 18 is a graph showing the change over time in the remaining capacity of the battery 6 when the power generation control of this embodiment is performed. In FIG. 18, the horizontal axis is time [s], and the vertical axis is the remaining capacity of the battery 6. In FIG. 18, in the first cycle C1, a default value is used for the optimal power generation amount during transplantation and turning (during driving). In the second cycle C2, the optimal power generation amount during driving α obtained according to the performance of the first cycle C1 is used for the optimal power generation amount during transplantation and turning (during driving). Each cycle is composed of "transplantation" → "turning" → "transplantation" → "turning" → "transplantation" → "turning" → "transplantation" → "stop". That is, in each cycle, a set of "transplantation" and "turning" is repeated three times, and then "transplantation" is performed again, followed by "stop" for replenishment.

[0177] During each cycle, power is generated by the motor generator 4 during transplantation, but the remaining capacity of the battery 6 decreases due to the large discharge power during work using the motor 5. During each cycle, power is generated only by the motor generator 4 during turning, so the remaining capacity of the battery 6 increases. However, the turning time is short and the amount of power generated is minimal, so the increase in the remaining capacity of the battery 6 during turning is small. During each cycle, power is generated only by the motor generator 4 during a stop for replenishment, so the remaining capacity of the battery 6 increases. During a stop, the amount of power generated by the motor generator 4 is maximum and a certain amount of time can be secured for charging the battery 6, so the remaining capacity of the battery 6 can be significantly increased.

[0178] In the power generation control of this embodiment, the amount of power generated while the traveling machine body 1 is traveling is changed according to the work content performed during the work traveling along the straight path 74. This is related to the fact that the amount of power generated while traveling in each cycle is determined based on the actual value of the energy balance in the immediately preceding cycle.

[0179] For example, the number of transplants and turns repeated during the period from the start of the work run to the stop for seedling supply (one cycle) differs between a work (called a first work) in which a large number of seedling mats are used per unit area and a work (called a second work) in which a small number of seedling mats are used per unit area. Specifically, the number of repetitions of transplants and turns in one cycle is greater in the case of the second work than in the case of the first work. For this reason, the discharge power of the battery 6 during execution of one cycle is greater when the second work is performed than when the first work is performed. In such a case, since it is necessary to cover the increased discharge power, it may be preferable to make the optimal power generation amount during execution of one cycle greater when the second work is performed than when the first work is performed.

[0180] In principle, the field work machine 100 performs the power generation control described above, but when the traveling load becomes large, it performs traveling assistance (assisting the output of the engine 3) using the motor generator 4. For this reason, power generation may be stopped during work, and power may be consumed by the motor generator 4. In this case, since there is no power generation during work, the expected amount of power generation cannot be secured. Even in such a case, if the above-mentioned method for determining the optimal amount of power generation during travel is used, power will be generated in the next cycle, including the amount lost due to the traveling assistance, so that the lost power can basically be recovered.

[0181] However, in a field environment where the driving assistance occurs frequently, the remaining capacity of the battery 6 may not be sufficient. When the control device 41 determines that the remaining battery capacity is not sufficient, it is preferable that the control device 41 notifies the operator to wait before starting transplanting work while the field work machine 100 is stopped. The notification may be, for example, by voice guidance or a screen display.

[0182] <6. Points to note> Various technical features disclosed in this specification may be modified in various ways without departing from the spirit of the technical creation. Furthermore, multiple embodiments and modifications shown in this specification may be combined to the extent possible.

[0183] <7. Notes> An exemplary field work machine of the present invention may have a configuration (first configuration) including a traveling body having a traveling device, a work device supported on the traveling body, a prime mover that supplies driving force to the traveling device, a first rotating electric machine connected to an output shaft of the prime mover so as to be capable of transmitting power, and a second rotating electric machine that supplies driving force to the work device.

[0184] In the field work machine of the first configuration described above, the first rotating electric machine may be a motor generator, and the second rotating electric machine may be a motor (second configuration).

[0185] The field work machine of the first or second configuration may be further provided with a battery electrically connected to the first rotating electric machine and the second rotating electric machine (third configuration).

[0186] In a field work machine of any of the first to third configurations described above, the first rotating electric machine and the second rotating electric machine may be configured (fourth configuration) to be switchable between an electrically connected state and an electrically disconnected state.

[0187] The field work machine of any of the first to fourth configurations above may be configured (fifth configuration) to include a switching mechanism that switches the power transmission state between the first rotating electric machine and the second rotating electric machine between a connected state and a disconnected state.

[0188] In a field work machine of any of the first to fifth configurations described above, there may be a configuration (sixth configuration) in which the operating state of the first rotating electric machine is changed depending on a running load, which is a load applied to the prime mover during traveling, or an index value of the running load.

[0189] In the field work machine of the sixth configuration described above, the first rotating electric machine may be configured to stop power generation when the traveling load or the index value becomes equal to or greater than a first threshold value (seventh configuration).

[0190] In the field work machine of the seventh configuration described above, the first rotating electric machine may be configured (eighth configuration) to assist the output of the prime mover when the traveling load or the index value becomes equal to or greater than a second threshold value that is greater than the first threshold value.

[0191] The field work machine of the above-mentioned eighth configuration may be provided with a switching mechanism that switches the power transmission state between the first rotating electric machine and the second rotating electric machine between a connected state and a disconnected state, and when the running load or the index value becomes equal to or greater than a third threshold value that is greater than the second threshold value, the switching mechanism is switched to the connected state, and the second rotating electric machine assists the output of the first rotating electric machine without supplying driving force to the work device (ninth configuration).

[0192] In the field work machine of the first to fifth configurations described above, the prime mover may be an engine, and the device may include a continuously variable transmission that changes the speed of power from the engine and outputs it to the traveling device, and a control device that controls the engine, the first rotating electric machine, and the continuously variable transmission, and the control device may be configured to detect a rotational speed difference between a target rotational speed and an actual rotational speed of the engine, and when the rotational speed difference becomes equal to or greater than a predetermined rotational speed difference, to assist the output of the engine by the first rotating electric machine and to reduce the traveling speed by changing the speed ratio of the continuously variable transmission (tenth configuration).

[0193] In the field work machine of the above-mentioned tenth configuration, the control device may be configured (eleventh configuration) to perform the assist by increasing the target rotation speed of the engine when the rotation speed difference becomes equal to or greater than a predetermined rotation speed difference.

[0194] In the field work machine of the tenth or eleventh configuration described above, the control device may be configured to change the speed ratio after the start of the assist (twelfth configuration).

[0195] In the field work machine of any of the tenth to twelfth configurations above, the control device may be configured (thirteenth configuration) to execute the assist and the change in the speed ratio in a stepwise manner.

[0196] In a field work machine of any of the tenth to thirteenth configurations above, the control device may be configured (a fourteenth configuration) to stop the assist and to stop traveling by changing the speed ratio when it is determined that the discrepancy between the target rotation speed and actual rotation speed of the engine has not been resolved even after a predetermined time has elapsed since the start of the assist.

[0197] A field work machine of any of the above-mentioned tenth to fourteenth configurations may be provided with a differential lock unit that stops the differential drive of a differential mechanism that enables left and right wheels included in the traveling device to be driven differentially, and the control device may be configured to control the differential lock unit in accordance with the rotation speed difference to stop the differential drive (fifteenth configuration).

[0198] The field work machine of the third or fourth configuration may be equipped with a control device that controls the motor generator, and the control device may be configured to change the setting of the power generation amount of the first rotating electric machine that supplies power to the battery by generating electricity using the driving force of the prime mover, based on the traveling state of the traveling body (16th configuration).

[0199] In the field work machine of the above-mentioned 16th configuration, the first rotating electric machine may supply electric power to the battery by generating electricity using the driving force of the prime mover while the traveling body is traveling and while it is stopped, and the control device may be configured to set the amount of power generation larger when the traveling body is stopped compared to when the traveling body is traveling (17th configuration).

[0200] In a field work machine of the 16th or 17th configuration described above, the traveling machine body performs work traveling along a straight path and non-work traveling along a turning path connecting the straight paths, and the amount of power generated while the traveling machine body is traveling may be configured to be changed depending on the work content performed during the work traveling (18th configuration).

[0201] In the field work machine of any of the sixteenth to eighteenth configurations above, the stopping of the traveling body may be a configuration (a nineteenth configuration) in which the stopping is performed in order to replenish materials. [Explanation of symbols]

[0202] 1. Running body 2. Working device 2A...Planting equipment (work equipment) 3. Engine (prime mover) 4. Motor generator (first rotating electric machine) 5. Motor (second rotating electric machine) 6. Battery 9. Switching mechanism 11. Aircraft frame 12. Running gear 12a, 12b...wheels 41...Control device 61...Continuously variable transmission 62a···Diff lock section 74... Straight line path 75...Circling path 100, 100A... Field work machine 100R···Rice transplanter (field work machine)

Claims

1. A traveling machine body having a traveling device; A working device supported on the traveling machine body; A prime mover for supplying driving force to the traveling device; a first rotating electric machine connected to an output shaft of the prime mover so as to be capable of transmitting power; a second rotating electric machine that supplies a driving force to the working device; A field work machine comprising:

2. the first rotating electric machine is a motor generator, The field work machine according to claim 1 , wherein the second rotating electric machine is a motor.

3. The field work machine according to claim 1 or 2, further comprising a battery electrically connected to the first rotating electric machine and the second rotating electric machine.

4. The field work machine according to claim 3 , wherein the first rotating electric machine and the second rotating electric machine are switchably provided between an electrically connected state and an electrically disconnected state.

5. The field working machine according to claim 1 or 2, further comprising a switching mechanism that switches a power transmission state between the first rotating electric machine and the second rotating electric machine between a connected state and a disconnected state.

6. 3. The field work machine according to claim 1, wherein an operating state of the first rotating electric machine is changed in accordance with a running load, which is a load applied to the prime mover during travel, or an index value of the running load.

7. The field work machine according to claim 6 , wherein the first rotating electric machine stops generating power when the traveling load or the index value becomes equal to or greater than a first threshold value.

8. The field work machine according to claim 7 , wherein when the traveling load or the index value becomes equal to or greater than a second threshold value that is greater than the first threshold value, the first rotating electric machine assists the output of the prime mover.

9. a switching mechanism that switches a power transmission state between the first rotating electric machine and the second rotating electric machine between a connected state and a disconnected state, 9. The field work machine according to claim 8, wherein when the traveling load or the index value becomes equal to or greater than a third threshold value that is greater than the second threshold value, the switching mechanism is switched to the connected state, and the second rotating electric machine assists the output of the first rotating electric machine without supplying driving force to the work device.

10. The prime mover is an engine, a continuously variable transmission that changes the speed of the power from the engine and outputs the power to the traveling device; a control device that controls the engine, the first rotating electric machine, and the continuously variable transmission; Equipped with The control device includes: Detecting a difference between a target rotation speed and an actual rotation speed of the engine; 2. The field work machine according to claim 1, wherein, when the rotation speed difference becomes equal to or greater than a predetermined rotation speed difference, the output of the engine is assisted by the first rotating electric machine, and the travel speed is reduced by changing the speed ratio of the continuously variable transmission.

11. The field work machine according to claim 10, wherein the control device executes the assist by increasing a target rotation speed of the engine when the rotation speed difference becomes equal to or greater than a predetermined rotation speed difference.

12. The field work machine according to claim 10 or 11, wherein the control device changes the speed ratio after the assist is started.

13. The field work machine according to claim 10, wherein the control device executes the assist and the change in the speed ratio in a stepwise manner.

14. 11. The field work machine according to claim 10, wherein the control device, when it is determined that a discrepancy between the target rotation speed and the actual rotation speed of the engine has not been eliminated even after a predetermined time has elapsed since the start of the assist, stops the assist and stops the vehicle from traveling by changing the speed ratio.

15. a differential lock unit that stops differential driving of a differential mechanism that enables differential driving of left and right wheels included in the traveling device, The field working machine according to claim 10, wherein the control device controls the differential lock unit in accordance with the rotation speed difference to stop the differential drive.

16. A control device for controlling the motor generator is provided, The field work machine according to claim 3 , wherein the control device changes a setting of an amount of power generated by the first rotating electric machine that supplies electric power to the battery by generating power using a driving force of the prime mover, based on a traveling state of the traveling machine body.

17. The first rotating electric machine supplies electric power to the battery by generating electric power using a driving force of the prime mover while the traveling machine body is traveling and while the traveling machine body is stopped, The field work machine according to claim 16, wherein the control device sets the amount of power generation while the traveling body is stopped to be greater than when the traveling body is traveling.

18. The traveling machine body performs work traveling along a straight path and non-work traveling along a turning path connecting the straight paths, The field work machine according to claim 17 , wherein the amount of power generated while the traveling machine body is traveling is changed depending on the type of work performed during the work traveling.

19. The field work machine according to claim 17, wherein the stopping of the traveling machine body is a stopping performed in order to replenish materials.

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