Work vehicle

Abstract

The invention provides a technology capable of ensuring straight movement of a work vehicle even if a part of straight movement power flows into a turning power transmission path connected with a turning electric motor. This work vehicle is provided with: an electric motor for straight movement that generates power for straight movement; and a turning electric motor for generating turning power. When straight travel is performed by driving the straight travel electric motor, if there is a difference between the rotational speed of the turning electric motor and the target rotational speed of the turning electric motor, the rotational speed of the turning electric motor is restored to the target rotational speed.

Description

Technical Field

[0001] The present invention relates to a work vehicle. Background Art

[0002] As a conventional technology, a work vehicle including an electric motor as a driving source for traveling is known (for example, see Patent Document 1).

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2020-48585

[0004] However, in recent years, work vehicles have been proposed that are equipped with both a straight-moving electric motor that generates straight-moving power and a turning electric motor that generates turning power. When such work vehicles are driven straight by the straight-moving electric motor, if, for example, some of the straight-moving power accidentally flows into the turning power transmission path connected to the turning electric motor, this power may function as turning power. In this case, unintended turning power is generated, potentially hindering the work vehicle's straight-moving operation. Summary of the Invention

[0005] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a technology that can ensure the straightness of a work vehicle even if part of the straight running power flows into the turning power transmission path connected to the turning electric motor.

[0006] A work vehicle according to one aspect of the present invention includes: an electric motor for straight travel that generates power for straight travel; and an electric motor for turning that generates power for turning. During straight travel driven by the electric motor for straight travel, if a difference occurs between the rotational speed of the turning electric motor and a target rotational speed of the turning electric motor, the rotational speed of the turning electric motor is restored to the target rotational speed.

[0007] According to the above configuration, even if a part of the straight-moving power flows into the turning power transmission path connected to the turning electric motor, the straight-moving performance of the work vehicle can be ensured. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a diagram showing a schematic configuration of a work vehicle according to one embodiment of the present invention.

[0009] Figure 2 It is a schematic diagram schematically showing the structure of the travel drive device equipped in the above-mentioned work vehicle.

[0010] Figure 3 This is a block diagram schematically showing the configuration of the electrical system of the work vehicle.

[0011] Figure 4It is a block diagram schematically showing the configuration of the control system of the above-mentioned work vehicle.

[0012] Figure 5 This is an explanatory diagram for explaining the state of the turning electric motor of the travel drive device.

[0013] Figure 6 This is a flowchart showing the flow of control related to the turning electric motor when the work vehicle travels straight.

[0014] Figure 7 This is an explanatory diagram for explaining a modified example of the state of the above-mentioned electric motor for turning.

[0015] Figure 8 This is a flowchart showing a flow of a modified example of control related to the turning electric motor when the work vehicle travels straight.

[0016] Description of Reference Numerals

[0017] 1…work vehicle; 111d…battery; C1…stopped state; C2…rotating state; EM1…electric motor for straight travel; EM2…electric motor for turning; RA…allowable speed; RM…speed (speed of the electric motor for turning); RT…target speed (target speed of the electric motor for turning). DETAILED DESCRIPTION

[0018] The following describes embodiments of the present invention based on the drawings.

[0019] [1. Schematic structure of work vehicle]

[0020] Figure 1 This figure schematically illustrates the configuration of a work vehicle 1 according to one embodiment of the present invention. Work vehicle 1 is used for agricultural work, construction work, and other tasks. Work vehicle 1 includes a vehicle body 10 and a remote control device 20 provided independently of vehicle body 10. Vehicle body 10 includes a traveling body 11 that travels on the ground and a work implement 12 coupled to traveling body 11.

[0021] The remote control device 20 (also referred to as a remote operating device) enables an operator located at a distance from the vehicle body 10 to operate the vehicle body 10. In other words, the vehicle body 10 is remotely operated by the remote control device 20. Furthermore, the operation of the vehicle body 10 by the remote control device 20, that is, the operation of the vehicle body 10 by the operator manually, is referred to as manual driving.

[0022] In this embodiment, the work vehicle 1 is configured to be capable of traveling by automatic driving in addition to the manual driving described above. The automatic driving described above refers to the use of a control device 113a (see Figure 3 and Figure 4 ) controls devices related to driving (e.g., the driving drive device 111b described later) to at least autonomously perform steering operations along a predetermined path. Furthermore, autonomous driving may be configured to autonomously perform at least one of, for example, adjusting the driving speed (also referred to simply as speed) and performing operations using the work machine 12 in addition to steering operations. Furthermore, the work vehicle 1 is not limited to the above configuration; for example, it may be capable of manual driving but not automatic driving, or it may be capable of automatic driving but not manual driving.

[0023] Here, the directions used in the description (especially the directions related to the vehicle body 10) are defined as follows. The direction in which the traveling body 11 and the working machine 12 are arranged is referred to as the front-to-back direction, the direction in which the working machine 12 is located when viewed from the traveling body 11 is referred to as "rear", and the opposite direction is referred to as "front". In addition, from the rear toward the front, the left side is referred to as "left", and the right side is referred to as "right". In addition, the direction of gravity perpendicular to the front-to-back direction and the left-right direction is referred to as the up-down direction, the upstream side of the gravity direction is referred to as "up", and the downstream side is referred to as "down". In the accompanying drawings, as needed, the "F" symbol is used to indicate the front, the "B" symbol is used to indicate the rear, the "R" symbol is used to indicate the right, the "L" symbol is used to indicate the left, the "U" symbol is used to indicate the top, and the "D" symbol is used to indicate the bottom. In addition, these directions are merely names used for explanation and are not intended to limit the actual positional relationship and direction.

[0024] In the present embodiment, the work machine 12 is arranged behind the travel body 11 , but the present invention is also applicable to a work vehicle 1 in which the work machine 12 is arranged in front of the travel body 11 .

[0025] The traveling body 11 includes a main body portion 111 and a traveling portion 112 disposed below the main body portion 111. The main body portion 111 includes an outer cover 111a, a traveling drive device 111b disposed on the front side of the interior covered by the outer cover 111a, and a working machine drive device 111c disposed on the rear side of the interior covered by the outer cover 111a.

[0026] The travel drive device 111b includes a travel electric motor EM as a driving source and a travel power transmission unit TM (see FIG. 1 ) for transmitting the rotational power from the travel electric motor EM to the travel unit 112. Figure 2 ). The structure of the travel drive device 111b will be described later. In addition, the "rotational power" may be simply referred to as "power" below.

[0027] The work machine drive device 111c includes a PTO (Power Take Off) electric motor 111c1 as a drive source, and a PTO power transmission unit (not shown) capable of transmitting the rotational power from the PTO electric motor 111c1 to the outside of the travel machine body 11. Furthermore, the drive source provided by the work machine drive device 111c may be a drive source other than an electric motor, such as an engine. Furthermore, in this embodiment, the travel drive device 111b and the work machine drive device 111c are each provided with an electric motor (drive source), but a configuration in which a shared electric motor (drive source) is also possible.

[0028] In addition to the travel drive unit 111b and the work machine drive unit 111c, a battery 111d is housed within the housing 111a. Specifically, the work vehicle 1 includes the battery 111d. The battery 111d is, for example, a lithium-ion battery. The battery 111d can be constructed by combining multiple cells or a single cell.

[0029] As an example, a lamp 111e, a positioning antenna 111f, an alarm lamp 111g, and the like are arranged outside the housing 111a.

[0030] The traveling portion 112 supports the main body portion 111 so that it can travel. Specifically, the traveling portion 112 includes a pair of left and right crawler tracks 112a. Each left and right crawler track 112a includes a crawler frame 112b extending in the front-rear direction. Each crawler frame 112b is mounted on the lower surface of the main body portion 111. A drive sprocket 112c is arranged at the front end of the crawler frame 112b as a drive wheel. Power is transmitted from the travel electric motor EM to the drive sprocket 112c via the travel power transmission unit TM. A driven sprocket 112d is arranged at the rear end of the crawler frame 112b as a driven wheel. The driven sprocket 112d is rotatably supported by the crawler frame 112b. On the crawler frame 112b, a plurality of runners 112e are rotatably supported between the drive sprocket 112c and the driven sprocket 112d. Crawler belt 112f is wound around drive sprocket 112c, driven sprocket 112d, and a plurality of runners 112e to form crawler belt 112a.

[0031] Furthermore, in this embodiment, the crawler track 112a is constructed by arranging a drive wheel (drive sprocket 112c) and a driven wheel (driven sprocket 112d) in the front-to-rear direction and wrapping around a crawler belt 112f. However, other structures are also possible. For example, the crawler track may be a type that wraps around a crawler belt in a triangular shape, with one drive wheel and two driven wheels. Furthermore, in this embodiment, the traveling section 112 is a crawler track type, but it may also be a type other than a crawler track type, such as a wheel type.

[0032] The working machine 12 is installed via the hook portion 13 so as to be able to be raised and lowered relative to the traveling machine body 11. In addition, the hook portion 13 includes a working machine driving device 111c. The working machine 12 is replaceably installed on the hook portion 13. That is, the working machine 12 can be installed in various types. Figure 1 In the embodiment, the working machine 12 is a tiller. In addition to the tiller, the working machine 12 may be, for example, a plow, a ridging device, a fertilizer application device, a pesticide spreading device, a harvesting device, a mowing device, a snow removal device, or the like.

[0033] [2. Structure of the travel drive device]

[0034] based on Figure 2 The structure of the travel drive device 111b will be described. Figure 2 111b is a schematic diagram schematically showing the structure of the travel drive device 111b. Figure 2 In the figure, components necessary for explaining the features of the present embodiment are shown, and illustration of general components is omitted.

[0035] The electric motor EM for driving includes an electric motor for straight driving EM1 and an electric motor for turning EM2. That is, the work vehicle 1 includes an electric motor for straight driving EM1 and an electric motor for turning EM2. The electric motor for straight driving EM1 and the electric motor for turning EM2 are driven by the power supplied from the battery 111d. In addition, the electric motor for straight driving EM1 and the electric motor for turning EM2 are arranged in a left-right direction on the main body 111. Figure 2 In FIG. 1 , for convenience, the positional relationship between the electric motor EM1 for straight travel and the electric motor EM2 for turning is shown in the figure in a manner different from the positional relationship in the machine body 111 .

[0036] The driving power transmission unit TM includes a pair of left and right planetary speed change mechanisms TM1L and TM1R. The left and right planetary speed change mechanisms TM1L and TM1R are arranged symmetrically on the sun shaft TM2. The left and right planetary speed change mechanisms TM1L and TM1R each have a plurality of (for example, three) planetary gears TM1a. In the left planetary speed change mechanism TM1L, each of the plurality of planetary gears TM1a is rotatably supported on a planetary carrier TM1b arranged on the left side. In the right planetary speed change mechanism TM1R, each of the plurality of planetary gears TM1a is rotatably supported on a planetary carrier TM1b arranged on the right side. In each planetary speed change mechanism TM1L and TM1R, the plurality of planetary gears TM1a are positioned at the same radius with the sun shaft TM2 as the center, and are arranged to mesh with the sun gears TM1c fixed to the left and right ends of the sun shaft TM2, respectively.

[0037] In the left and right planetary speed change mechanisms TM1L and TM1R, ring gears TM1d are respectively arranged concentrically with the sun shaft TM2. Each ring gear TM1d has internal teeth on its inner circumference and external teeth on its outer circumference. Each ring gear TM1d is arranged so that multiple planetary gears TM1a mesh with the internal teeth. Each ring gear TM1d is rotatably supported via bearings on the sun shaft TM2 or on a center shaft TM3 that projects outward in the left-right direction from the planetary carrier TM1b.

[0038] The rotational power of the output shaft EM1a of the straight-moving electric motor EM1 is transmitted to the left and right planetary speed change mechanisms TM1L and TM1R via the first gear train TM4 and the sun shaft TM2. The first gear train TM4 comprises multiple gears. In particular, it includes a first sun gear TM4a, which is fixed to the sun shaft TM2.

[0039] The rotational power transmitted to the left planetary speed change mechanism TM1L is transmitted via the planetary carrier TM1b to the left bevel gear TM5L fixed to the left end of the center axis TM3 of the planetary carrier TM1b. Similarly, the rotational power transmitted to the right planetary speed change mechanism TM1R is transmitted via the planetary carrier TM1b to the right bevel gear TM5R fixed to the right end of the center axis TM3 of the planetary carrier TM1b.

[0040] The rotational power transmitted to the left bevel gear TM5L is transmitted to the relay shaft TM6. More specifically, the relay shaft TM6 has bevel gears TM7 fixed to both ends. The left bevel gear TM5L meshes with one of the bevel gears TM7 at both ends of the relay shaft TM6.

[0041] The rotational power transmitted to the relay shaft TM6 is transmitted to the external output shaft TM8. More specifically, a bevel gear TM9 is fixed to one end (right end) of the external output shaft TM8. The other of the bevel gears TM7 at both ends of the relay shaft TM6 meshes with the bevel gear TM9 of the external output shaft TM8. The left drive sprocket 112c (also refer to Figure 1 ).

[0042] Similarly, the rotational power transmitted to the right bevel gear TM5R is transmitted to the relay shaft TM6. More specifically, the relay shaft TM6 has bevel gears TM7 fixed to both ends. The right bevel gear TM5R meshes with one of the bevel gears TM7 at both ends of the relay shaft TM6.

[0043] The rotational power transmitted to the relay shaft TM6 is transferred to the external output shaft TM8. More specifically, a bevel gear TM9 is fixed to one end (the left end) of the external output shaft TM8. The other of the bevel gears TM7 at the two ends of the relay shaft TM6 meshes with the bevel gear TM9 of the external output shaft TM8. The right drive sprocket 112c is fixed to the other end (the right end) of the external output shaft TM8.

[0044] The rotational power of the output shaft EM2a of the turning electric motor EM2 is transmitted to the steering shaft TM11 via the second gear train TM10. The second gear train TM10 includes multiple gears. In particular, the second gear train TM10 includes a second sun gear TM10a, which is fixed to the steering shaft TM11.

[0045] The rotational power transmitted to the steering shaft TM11 via the second gear train TM10 is transmitted to the left and right planetary speed change mechanisms TM1L and TM1R. More specifically, the left transmission gear TM12L, fixed to the left end of the steering shaft TM11, meshes with the external teeth of the ring gear TM1d of the left planetary speed change mechanism TM1L. Therefore, the rotational power transmitted to the steering shaft TM11 is directly transmitted to the ring gear TM1d of the left planetary speed change mechanism TM1L. Meanwhile, the right transmission gear TM12R, fixed to the right end of the steering shaft TM11, meshes with the counter gear TM14 attached to the counter shaft TM13. This counter gear TM14 meshes with the external teeth of the ring gear TM1d of the right planetary speed change mechanism TM1R. Therefore, the rotational power transmitted to the steering shaft TM11 is reversed in direction by the counter gear TM14 before being transmitted to the ring gear TM1d of the right planetary speed change mechanism TM1R.

[0046] For example, when the straight-moving electric motor EM1 is stopped, the sun shaft TM2 and the left and right sun gears TM1c are fixed. In this embodiment, "rotation of the straight-moving electric motor EM1" refers to "rotation of the output shaft EM1a of the straight-moving electric motor EM1." Similarly, "rotation of the turning electric motor EM2" refers to "rotation of the output shaft EM2a of the turning electric motor EM2."

[0047] Therefore, when the electric motor EM2 for turning rotates forward (or reversely), the left and right ring gears TM1d rotate at the same speed in opposite directions. Here, it is assumed that the ring gear TM1d on the left rotates forward and the ring gear TM1d on the right rotates reversely. In this case, the planetary gear TM1a and the planetary carrier TM1b on the left rotate forward with the sun shaft TM2 as the center, and the planetary gear TM1a and the planetary carrier TM1b on the right rotate reversely with the sun shaft TM2 as the center. Therefore, the external output shaft TM8 to which the rotational power is transmitted from the center shaft TM3 of the planetary carrier TM1b on the left via the relay shaft TM6 rotates forward, and the external output shaft TM8 to which the rotational power is transmitted from the center shaft TM3 of the planetary carrier TM1b on the right via the relay shaft TM6 rotates reversely. As a result, the left crawler 112a (refer to Figure 1 ) moves forward, and the right crawler track 112a moves backward. In this case, the work vehicle 1 turns right center on the spot (spin turn). That is, the turning electric motor EM2 generates turning power.

[0048] On the other hand, when the straight-moving electric motor EM1 is rotated, its rotational power is transmitted to the sun shaft TM2, as described above. When the turning electric motor EM2 is stopped (specifically, the output shaft EM2a of the turning electric motor EM2 is fixed), the left and right ring gears TM1d stop rotating, becoming fixed. Therefore, the rotational power transmitted to the sun shaft TM2 is transmitted equally to the left and right external output shafts TM8 via the left and right planetary speed change mechanisms TM1L and TM1R. As a result, the left and right drive sprockets 112c rotate in the same direction and at the same speed, allowing the work vehicle 1 to travel straight. In other words, the work vehicle 1 moves forward or backward depending on the rotational direction of the straight-moving electric motor EM1. Thus, the straight-moving electric motor EM1 generates power for straight-moving travel.

[0049] Based on the above principle, the rotation speed and rotation direction of the electric motor EM1 for straight driving and the rotation speed RM of the electric motor EM2 for turning are combined. Figure 5 ) and the direction of rotation are appropriately combined and controlled to enable the work vehicle 1 to travel. Furthermore, in this embodiment, the travel of the work vehicle 1 includes straight travel and turning travel. Straight travel of the work vehicle 1 refers to the work vehicle 1 simply moving forward or backward. Turning travel of the work vehicle 1 includes not only the work vehicle 1 turning left or right on the spot, but also the work vehicle 1 turning left or right while moving forward or backward.

[0050] However, when the work vehicle 1 is traveling straight, that is, when the straight-moving electric motor EM1 is rotating, if the turning electric motor EM2 (specifically, the output shaft EM2a) is freely rotatable (unfixed), the left and right ring gears TM1d are also freely rotatable. In this state, if, for example, either of the left and right crawler tracks 112a becomes stuck on the ground, increasing resistance (making it difficult to drive), the rotational power (of the straight-moving electric motor EM1) transmitted to the sun shaft TM2 will no longer be equally transmitted to the left and right external output shafts TM8.

[0051] As an example, assume that the resistance of the left crawler track 112a increases. Consequently, at least a portion of the rotational power transmitted to the sun shaft TM2, which is transmitted to the left planetary transmission mechanism TM1L, is transmitted to the right planetary transmission mechanism TM1R via the left drive gear TM12L, the steering shaft TM11, the right drive gear TM12R, and the counter gear TM14. In other words, the straight-moving power flows into the turning power transmission path. Consequently, the rotational power transmitted directly from the sun shaft TM2 and the rotational power transmitted via the steering shaft TM11 and other mechanisms are transmitted together to the right external output shaft TM8. As a result, the rotational speed of the right drive sprocket 112c (crawler track 112a) increases compared to the left drive sprocket 112c (crawler track 112a), causing the work vehicle 1 to turn left. This influx of the straight-moving power into the turning power transmission path generates unexpected turning power, hindering the work vehicle 1's straight-moving travel. Furthermore, at this time, the steering shaft TM11 is rotating, so the (freely rotatable) turning electric motor EM2 is rotated (via the second gear train TM10 ).

[0052] The rotation speed and rotation direction of the straight-moving electric motor EM1 and the rotation speed RM and rotation direction of the turning electric motor EM2 are adjusted by operating an operating unit (not shown) such as a lever provided on the remote operating device 20 .

[0053] [3. Structure of the electrical system of the work vehicle]

[0054] based on Figure 3 The configuration of the electrical system of the work vehicle 1 will be described. Figure 3 It is a block diagram schematically showing the configuration of the electrical system of the work vehicle 1 .

[0055] The work vehicle 1 includes a plurality of electrical devices 113. The plurality of electrical devices 113 include a control device 113a, a charger 113b, an inverter 113c, a relay box 113d, a junction box 113e, a DC-DC converter 113f, and a low-voltage battery 113g. The plurality of electrical devices 113 are arranged on the main body 111 of the traveling body 11 (see Figure 1 ).

[0056] The plurality of electrical devices 113 receive power from a battery 111d. More specifically, each device included in the plurality of electrical devices 113 is electrically connected to the battery 111d directly or via other devices included in the plurality of electrical devices 113. For example, the relay box 113d included in the plurality of electrical devices 113 is directly connected to the battery 111d. Furthermore, the inverter 113c included in the plurality of electrical devices 113 is electrically connected to the battery 111d via the relay box 113d and the junction box 113e.

[0057] The control device 113a is a computer device that performs electrical control of various components of the work vehicle 1. The structure of the control device 113a will be described later. The charger 113b converts AC voltage supplied from an external power source (not shown) via a charging cable (not shown) into DC voltage. A charging port (not shown) for connecting the charging cable is provided on the main body 111 of the travel vehicle 11.

[0058] The inverter 113c converts the DC voltage supplied from the battery 111d into AC voltage and supplies it to the straight-moving electric motor EM1, the turning electric motor EM2, and the PTO electric motor 111c1. This drives the straight-moving electric motor EM1, the turning electric motor EM2, and the PTO electric motor 111c1. The supply of AC voltage from the inverter 113c to the straight-moving electric motor EM1, the turning electric motor EM2, and the PTO electric motor 111c1 is based on a rotation command output from the control device 113a.

[0059] Relay box 113d is a battery control unit that controls the internal battery relay to control the input and output of battery 111d. Junction box 113e includes a charger relay, an inverter relay, a fuse, and other components. The voltage output from charger 113b is supplied to battery 111d via junction box 113e and relay box 113d. This allows electricity to accumulate in battery 111d. Furthermore, the voltage output from battery 111d is supplied to inverter 113c via relay box 113d and junction box 113e. For example, the electricity stored in battery 111d is supplied to turning electric motor EM2 via relay box 113d, junction box 113e, and inverter 113c.

[0060] DC-DC converter 113f (also referred to simply as a converter) steps down the high-voltage (e.g., 350V) DC voltage supplied from battery 111d via junction box 113e to a low voltage (e.g., 12V). Low-voltage battery 113g is comprised of, for example, a lead-acid battery. Low-voltage battery 113g is connected to DC-DC converter 113f and stores the power stepped down by DC-DC converter 113f.

[0061] [4. Structure of the control system of the work vehicle]

[0062] based on Figure 4 The configuration of the control system of the work vehicle 1 will be described. Figure 4 1 is a block diagram schematically showing the structure of the control system of the work vehicle 1. Figure 4 Components necessary for describing the features of this embodiment are shown, and description of general components is omitted.

[0063] The control device 113a is configured to include, for example, a computing device, an input / output unit, and a storage unit 113a1. The computing device is, for example, a processor or a microprocessor. The storage unit 113a1 is a main storage device such as a ROM (Read Only Memory) or a RAM (Random Access Memory). The storage unit 113a1 may further include an auxiliary storage device such as an HDD (Hard Disk Drive) or an SSD (Solid State Drive). Various programs and data are stored in the storage unit 113a1. The computing device reads various programs from the storage unit 113a1 and executes computing processing in accordance with the programs. The programs stored in the storage unit 113a1 can be provided, for example, via a computer-readable non-volatile recording medium. As another example, the program can also be provided from a program providing server via a communication line such as the Internet.

[0064] By cooperating with the above hardware and software, the control device 113a can function as the travel control unit 113a2 and the work machine control unit 113a3. The control device 113a can be composed of a single piece of hardware or a plurality of pieces of hardware that can communicate with each other.

[0065] In addition, as described above, the travel control unit 113a2 and the work machine control unit 113a3 of the control device 113a can be implemented by causing the computing device to execute computing processing in accordance with the program, that is, by software, but can also be implemented by other methods. At least any one of the travel control unit 113a2 and the work machine control unit 113a3 can also be implemented using, for example, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or the like. That is, at least any one of the travel control unit 113a2 and the work machine control unit 113a3 can also be implemented by hardware using a dedicated IC, etc. In addition, at least any one of the travel control unit 113a2 and the work machine control unit 113a3 can also be implemented using both software and hardware. In addition, the travel control unit 113a2 and the work machine control unit 113a3 are conceptual structures. Therefore, the functions performed by one component can also be dispersed across multiple components, and the functions possessed by multiple components can also be integrated into one component.

[0066] The travel control unit 113a2 controls the travel drive device 111b (via the inverter 113c), particularly the straight travel electric motor EM1 and the turning electric motor EM2, depending on whether the work vehicle 1 is in manual travel or automatic travel. More specifically, during manual travel, the travel control unit 113a2 controls the travel drive device 111b based on the remote control unit 20 (see FIG. Figure 1 ) driving instructions, controls the straight-moving electric motor EM1 and the turning electric motor EM2. During automatic driving, the driving control unit 113a2 automatically (autonomously) controls the straight-moving electric motor EM1 and the turning electric motor EM2 so that the driving body 11 travels along a predetermined path.

[0067] The work machine control unit 113a3 adjusts the lifting position (height from the ground) of the work machine 12 based on the lifting instruction from the remote control device 20. In addition, the work machine control unit 113a3 controls the work machine drive device 111c based on the switching instruction from the remote control device 20 to control the switching of power transmission to the work machine 12.

[0068] The control device 113a is connected to the positioning communication unit 113h, the communication processing unit 113j, and the sensor 113k. The positioning communication unit 113h, the communication processing unit 113j, and the sensor 113k are included in the plurality of electrical devices 113 (see Figure 3 ).

[0069] The positioning communication unit 113h includes a positioning antenna 111f (see Figure 1), the positioning antenna 111f receives a positioning signal from a positioning satellite, and obtains the position of the vehicle body 10 as, for example, latitude and longitude information. The positioning communication unit 113h, for example, performs positioning using the well-known RTK-GNSS (Real Time Kinematic GNSS) method after receiving a positioning signal from a base station (not shown) using an appropriate method. The positioning communication unit 113h outputs the position information of the vehicle body 10 to the control device 113a. In addition, the positioning communication unit 113h may also perform positioning using other methods such as the DGNSS (Differential GNSS) method. In addition, the work vehicle 1 may also be configured to replace or be provided with a positioning-capable quantum compass, for example, in addition to the positioning communication unit 113h.

[0070] The communication processing unit 113j communicates with the remote control device 20 via the communication antenna 113j1. The communication antenna 113j1 is an antenna for wireless communication with the remote control device 20. Wireless communication can utilize a wireless LAN (Local Area Network) such as Wi-Fi (registered trademark).

[0071] The sensor 113k detects information related to the vehicle body 10 and outputs the detected information to the control device 113a. In this embodiment, the sensor 113k includes multiple sensors. Each of the multiple sensors is connected to the control device 113a so as to input signals to the control device 113a. Examples of the multiple sensors include an inertial measurement unit, an obstacle sensor, a speed sensor, a lift position sensor, and a rotation speed sensor.

[0072] The inertial measurement device includes a three-axis angular velocity sensor and a three-directional acceleration sensor, and is capable of measuring the posture of the traveling body 11. The obstacle sensor detects obstacles around the vehicle body 10 and may be, for example, an ultrasonic sensor, a camera, radar, or LiDAR (Light Detection and Ranging). The speed sensor detects the speed of the traveling body 11. The lift position sensor detects the lift position (height from the ground) of the working machine 12. The rotational speed sensor detects the rotational speed of the output shaft of the electric motor (for example, the output shaft EM2a of the turning electric motor EM2).

[0073] The positioning communication unit 113h and some sensors 113k (e.g., inertial measurement devices) are used when the work vehicle 1 is autonomously traveling. In other words, the positioning communication unit 113h and some sensors 113k are not essential for the work vehicle 1 to travel based on instructions from the remote control device 20.

[0074] [5. Control of the electric motor for turning during straight driving]

[0075] The control of the electric motor EM2 for turning when the work vehicle 1 (particularly the traveling body 11) is traveling straight ahead will be described. Figure 5 The state of the turning electric motor EM2 will be described. Figure 5 This is an explanatory diagram for explaining the state of the turning electric motor EM2.

[0076] The turning electric motor EM2, specifically, the output shaft EM2a of the turning electric motor EM2 (see Figure 2 ) is represented by a rotational speed RM (also referred to as an actual rotational speed), with a stopped state C1 and a rotating state C2 provided. In this embodiment, the "rotational speed RM of the output shaft EM2a of the turning electric motor EM2" is also referred to simply as the "rotational speed RM of the turning electric motor EM2." Furthermore, the "rotational speed of the output shaft EM1a of the straight-moving electric motor EM1" is also referred to simply as the "rotational speed of the straight-moving electric motor EM1."

[0077] The stopped state C1 includes a state in which the turning electric motor EM2, specifically, the output shaft EM2a of the turning electric motor EM2, is stopped. In the present embodiment, when the work vehicle 1 is traveling straight, the target rotation speed RT of the turning electric motor EM2 is 0 rpm. Therefore, in the present embodiment, the stopped state C1 includes a state in which the rotation speed RM of the turning electric motor EM2 is consistent with the target rotation speed RT (for example, see Figure 5 The first speed RM1).

[0078] The rotation state C2 includes a state in which the turning electric motor EM2, specifically, the output shaft EM2a of the turning electric motor EM2, is rotating. In the present embodiment, when the work vehicle 1 is traveling straight, the rotation state C2 includes a state in which the rotation speed RM of the turning electric motor EM2 is different from the target rotation speed RT (0 rpm in the present embodiment) (for example, refer to Figure 5 That is, the rotation state C2 can also be referred to as a state in which a difference occurs between the rotation speed RM of the turning electric motor EM2 and the target rotation speed RT.

[0079] Next, based on Figure 6 The flow of control related to the turning electric motor EM2 when the work vehicle 1 is traveling straight will be described. Figure 6 This is a flowchart showing the flow of control related to the turning electric motor EM2 when the work vehicle 1 travels straight. Figure 6The flowchart shown starts, for example, when the work vehicle 1 is started.

[0080] In step S1, the travel control unit 113a2 (see Figure 4 ) determines whether the work vehicle 1 is traveling straight. In this embodiment, the above-mentioned determination conditions include that the target speed of the electric motor EM1 for straight travel is 0 rpm and the target speed RT of the electric motor EM2 for turning is 0 rpm (refer to Figure 5 ) is 0 rpm. However, the target speed of the straight-moving electric motor EM1 other than 0 rpm may be excluded from the determination conditions. As described above, the target speed of the straight-moving electric motor EM1 and the target speed RT of the turning electric motor EM2 are adjusted by operating the operating unit provided on the remote control device 20.

[0081] Furthermore, when the conditions for determination are met (when the work vehicle 1 is traveling straight), power is supplied from the battery 111d to the electric motor EM1 for traveling straight according to the target speed. Therefore, the electric motor EM1 for traveling straight rotates (is driven). On the other hand, the power supply from the battery 111d is cut off to the electric motor EM2 for turning. If the power supply to the electric motor EM2 for turning is cut off, then (specifically, the output shaft EM2a of the electric motor EM2 for turning) becomes rotatable. Therefore, the electric motor EM2 for turning does not rotate (is not driven) and enters the stopped state C1 (see Figure 5 ).

[0082] If the work vehicle 1 is traveling straight (YES in step S1), the process proceeds to the next step S2. If the work vehicle 1 is not traveling straight, that is, if the work vehicle 1 is parked or turning (NO in step S1), this flowchart ends.

[0083] In step S2, the travel control unit 113a2 determines whether the turning electric motor EM2 is in the stopped state C1. In this embodiment, whether the turning electric motor EM2 is in the stopped state C1 is determined based on the sensor 113k (see Figure 4) is determined based on the rotational speed RM (actual rotational speed) of the turning electric motor EM2 detected by the rotational speed sensor included in the turning electric motor EM2. More specifically, if the rotational speed RM of the turning electric motor EM2 detected by the rotational speed sensor matches the target rotational speed RT of the turning electric motor EM2 (0 rpm in the present embodiment), it is determined that the turning electric motor EM2 is in the stopped state C1. On the other hand, if there is a difference between the rotational speed RM of the turning electric motor EM2 and the target rotational speed RT of the turning electric motor EM2 (0 rpm in the present embodiment), it is determined that the turning electric motor EM2 is not in the stopped state C1, that is, is in the rotating state C2. If the turning electric motor EM2 is in the stopped state C1 (YES in step S2), the process proceeds to step S3. If the turning electric motor EM2 is not in the stopped state C1 (NO in step S2), the process proceeds to step S4.

[0084] In step S3, the travel control unit 113a2 controls the inverter 113c (see Figure 3 ), the power supply from the inverter 113c to the turning electric motor EM2 is cut off. That is, when the work vehicle 1 is traveling straight, the power supply from the battery 111d to the turning electric motor EM2 is cut off in the stopped state C1. In addition, as described above, if the power supply to the turning electric motor EM2 is cut off, the turning electric motor EM2 (specifically, the output shaft EM2a of the turning electric motor EM2) becomes rotatable. Therefore, for example, the steering shaft TM11 connected to the output shaft EM2a of the turning electric motor EM2 via the second gear train TM10 also becomes rotatable (see Figure 2 ) When the power supply from the inverter 113c to the turning electric motor EM2 is cut off, the process returns to step S1.

[0085] In step S4, the driving control unit 113a2 controls the inverter 113c to supply power from the inverter 113c to the turning electric motor EM2. Specifically, when the work vehicle 1 is traveling straight, the turning electric motor EM2 is supplied with power from the battery 111d in the rotational state C2. More specifically, the driving control unit 113a2 outputs a command to the inverter 113c to set the rotational speed RM of the turning electric motor EM2 to the target rotational speed RT of the turning electric motor EM2 (0 rpm in this embodiment). Based on this command, the inverter 113c supplies power from the battery 111d to the turning electric motor EM2. For example, the inverter 113c reduces (subtly decreases) the power supplied to the turning electric motor EM2 by a predetermined amount at regular intervals. As a result, the rotational speed RM of the turning electric motor EM2 gradually decreases (step S5).

[0086] Furthermore, when power is supplied from the inverter 113c to the turning electric motor EM2 to control the turning electric motor EM2, for example, the steering shaft TM11 rotates due to the rotational power of the turning electric motor EM2 transmitted via the second gear train TM10. In other words, the steering shaft TM11 rotates in response to the rotation of the turning electric motor EM2.

[0087] In step S6, similar to step S2, the travel control unit 113a2 determines whether the turning electric motor EM2 has entered the stopped state C1. The determination in step S6 is identical to that in step S2, so details are omitted. If the turning electric motor EM2 is in the rotating state C2 (No in step S6), the process returns to step S4. Therefore, the processes of steps S4 and S5 are repeated until the turning electric motor EM2 enters the stopped state C1. If the turning electric motor EM2 is in the stopped state C1 (Yes in step S6), the process proceeds to step S3. Therefore, when the work vehicle 1 is traveling straight, if the turning electric motor EM2 transitions from the stopped state C1 to the rotating state C2, it returns to the stopped state C1. That is, when the work vehicle 1 is traveling straight, if the rotational speed of the turning electric motor EM2 differs from the target rotational speed RT of the turning electric motor EM2, it returns to the target rotational speed RT.

[0088] According to the above configuration, when the work vehicle 1 is driven straight by the straight-moving electric motor EM1, the following effects can be achieved. Specifically, even if, for example, a portion of the straight-moving power accidentally flows into the turning power transmission path, and the turning electric motor EM2 is rotating at a speed different from the target speed RT (0 rpm in this embodiment), the rotation speed RM of the turning electric motor EM2 can be maintained at the target speed RT. Once the rotation speed RM of the turning electric motor EM2 is maintained at the target speed RT, the rotation of the turning electric motor EM2 stops (the turning electric motor EM2 becomes stationary). This prevents the transfer of the already-inflowing straight-moving power, preventing it from functioning as turning power. Therefore, the work vehicle 1 can avoid the generation of unintended turning power, ensuring reliable straight-moving travel. Thus, even if a portion of the straight-moving power accidentally flows into the turning power transmission path connected to the turning electric motor EM2, the work vehicle 1's straight-moving performance can be maintained.

[0089] When the work vehicle 1 is traveling straight, if a difference occurs between the rotational speed RM of the turning electric motor EM2 and the target rotational speed RT, the rotational speed RM of the turning electric motor EM2 is restored to the target rotational speed RT. To reliably implement this configuration, the following configuration is preferred. Specifically, as in the present embodiment, the turning electric motor EM2 preferably returns to the stopped state C1 when transitioning from the stopped state C1 to the rotating state C2.

[0090] When the work vehicle 1 is traveling straight, the turning electric motor EM2 can be controlled to ensure the straightness of the work vehicle 1, while also reducing power consumption of the work vehicle 1 (the turning electric motor EM2) to extend the operating time of the work vehicle 1. From this perspective, the following configuration is preferred. Specifically, as in this embodiment, the turning electric motor EM2 is preferably supplied with power from the battery 111d in the rotating state C2, and the power supply from the battery 111d is interrupted in the stopped state C1.

[0091] Here, based on Figure 7 Modifications of the states (stop state C1 and rotating state C2) of the turning electric motor EM2 will be described. Figure 7 This is an explanatory diagram illustrating a modified example of the state of the turning electric motor EM2. In the modified example, when the work vehicle 1 is traveling straight, the stop state C1 includes the following state in addition to the state in which the rotation speed RM of the turning electric motor EM2 is consistent with the target rotation speed RT (0 rpm in this embodiment). That is, the stop state C1 includes the state in which the rotation speed RM of the turning electric motor EM2 is different from the target rotation speed RT but is less than the allowable rotation speed RA (for example, a rotation speed slightly greater than 0 rpm) (for example, see Figure 7 That is, the stopped state C1 of the turning electric motor EM2 may include a state in which the turning electric motor EM2U rotates at a speed less than the allowable rotation speed RA.

[0092] The rotation state C2 includes a state where the rotation speed RM of the turning electric motor EM2 is different from the target rotation speed RT and the rotation speed RM of the turning electric motor EM2 is equal to or higher than the allowable rotation speed RA (for example, see Figure 7 That is, the state in which the turning electric motor EM2 rotates less than the allowable rotational speed RA may be excluded from the rotational state C2 of the turning electric motor EM2.

[0093] From the perspective of reliably ensuring the time required to cut off the power supply from the battery 111d to the turning electric motor EM2 and reliably achieving an extension (increase) in the operating time of the work vehicle 1, the following configuration is preferred. Specifically, as in this modified example, the stopped state C1 of the turning electric motor EM2 preferably includes a state in which the turning electric motor EM2 is rotating at a speed less than the allowable rotational speed RA.

[0094] [6. Modification of Control of the Electric Motor for Turning During Straight Driving]

[0095] A modified example of the control related to the turning electric motor EM2 when the work vehicle 1 travels straight will be described. Figure 8 This is a flowchart showing a flow of a modified example of control related to the turning electric motor EM2 when the work vehicle 1 travels straight. Figure 8 The flowchart shown is the same as that shown in FIG. 1 except that step S7 is added. Figure 7 Therefore, the following description will focus on their differences and omit descriptions of the same points.

[0096] In step S6, if the turning electric motor EM2 is in the stopped state C1 (YES in step S6), the process proceeds to step S3. If the turning electric motor EM2 is not in the stopped state C1, that is, in the rotating state C2 (NO in step S6), the process proceeds to step S7.

[0097] In step S7, the driving control unit 113a2 determines whether a predetermined time (e.g., one second) has elapsed since the start of power supply from the battery 111d to the turning electric motor EM2, that is, since the initial execution of the process in step S4. If the predetermined time has elapsed (yes in step S7), the process proceeds to step S3. As described above, in step S3, the driving control unit 113a2 controls the inverter 113c to cut off the power supply from the inverter 113c to the turning electric motor EM2. Specifically, if the predetermined time has elapsed since the start of power supply from the battery 111d, the power supply from the battery 111d to the turning electric motor EM2 is cut off.

[0098] If the predetermined time has not elapsed (No in step S7), the process returns to step S4. Therefore, the processes of steps S4 and S5 are repeated until the turning electric motor EM2 reaches the stopped state C1 or until the predetermined time has elapsed. As described above, in steps S4 and S5, the driving control unit 113a2 controls the inverter 113c to supply power from the inverter 113c to the turning electric motor EM2, thereby gradually reducing the rotational speed RM of the turning electric motor EM2. Specifically, if the rotational speed RM of the turning electric motor EM2 gradually decreases within the predetermined time (before the predetermined time has elapsed), and the turning electric motor EM2 has returned to the stopped state C1 (has returned to the stopped state C1) (Yes in step S6), the process proceeds to step S3. Alternatively, if the rotational speed RM of the turning electric motor EM2 gradually decreases, even if the turning electric motor EM2 is in the rotating state C2 (has not returned to the stopped state C1), but the predetermined time has elapsed (Yes in step S7), the process proceeds to step S3.

[0099] For example, even if the turning electric motor EM2 is temporarily rotated at a speed different from the target speed RT (0 rpm in this embodiment), if it is subsequently stopped, the speed RM of the turning electric motor EM2 will naturally decrease due to frictional resistance within the driving power transmission unit TM. Therefore, in this case, even if power is supplied from the battery 111d to the turning electric motor EM2, the turning electric motor EM2 will naturally return to the stopped state C1 if the turning electric motor EM2 is not (forcibly) returned from the rotating state C2 to the stopped state C1. In particular, in this case, from the perspective of reducing power consumption of the work vehicle 1 (the turning electric motor EM2), the following configuration is preferred. Specifically, as in the modified example, the power supply from the battery 111d to the turning electric motor EM2 is preferably interrupted after a predetermined time (e.g., one second) has elapsed since the start of power supply from the battery 111d.

[0100] In the turning electric motor EM2, if the transition from the rotating state C2 to the stopped state C1 is performed smoothly, damage to components directly or indirectly connected to the turning electric motor EM2 (e.g., the second gear train TM10, the steering shaft TM11, etc.) can be avoided. Based on this viewpoint, as in the modified example, it is preferable to gradually reduce the rotational speed RM of the turning electric motor EM2 over a predetermined time period to restore the turning electric motor EM2 to the stopped state C1.

[0101] 〔7. Note〕

[0102] The work vehicle 1 described in this embodiment can also be expressed as a work vehicle as shown in the following supplementary notes.

[0103] The operating vehicles mentioned in Note (1) shall have:

[0104] an electric motor for straight travel, generating power for straight travel; and

[0105] The electric motor for turning generates the power for turning.

[0106] When the vehicle is traveling straight, driven by the electric motor for traveling straight,

[0107] If a difference occurs between the rotation speed of the turning electric motor and the target rotation speed of the turning electric motor, the rotation speed of the turning electric motor is restored to the target rotation speed.

[0108] The working vehicle in Note (2) is composed of the working vehicle described in Note (1).

[0109] When the vehicle is traveling straight, driven by the electric motor for traveling straight,

[0110] When the turning electric motor is switched from a stopped state to a rotating state, it returns to the stopped state.

[0111] The working vehicle in Note (3) is composed of the working vehicle described in Note (2).

[0112] A battery for storing electric power to be supplied to the electric motor for turning is provided.

[0113] The above-mentioned electric motor for turning is constructed as follows:

[0114] In the above rotation state, the power is supplied from the above battery.

[0115] In the stopped state, the power supply from the battery is cut off.

[0116] The working vehicle in Note (4) is composed of the working vehicle described in Note (3).

[0117] The stopped state includes a state in which the turning electric motor rotates at a speed less than the permissible rotation speed.

[0118] The working vehicle in Note (5) is composed of the working vehicle described in Note (3) or (4),

[0119] When a predetermined time has elapsed after the start of the power supply from the battery, the power supply from the battery to the turning electric motor is interrupted.

[0120] The working vehicle in Note (6) is composed of the working vehicle described in Note (5).

[0121] Within the predetermined time, the rotation speed of the turning electric motor is gradually reduced so that the turning electric motor returns to the stopped state.

[0122] As mentioned above, although embodiment of this invention was described, the scope of this invention is not limited to this, and it can be implemented expanding or changing within the range which does not deviate from the summary of this invention.

[0123] Industrial applicability

[0124] The present invention can be used in work vehicles such as agricultural machinery and construction machinery, for example.

Claims

1. A working vehicle, characterized in that: have: an electric motor for straight travel, generating power for straight travel; and The electric motor for turning generates turning power. During straight travel driven by the straight travel electric motor, If a difference occurs between the rotation speed of the turning electric motor and a target rotation speed of the turning electric motor, the rotation speed of the turning electric motor is restored to the target rotation speed.

2. The work vehicle according to claim 1, characterized in that: During straight travel driven by the straight travel electric motor, The turning electric motor returns to the stopped state when it is switched from the stopped state to the rotating state.

3. The work vehicle according to claim 2, characterized in that: A battery for storing electric power to be supplied to the turning electric motor is provided. The electric motor for turning is constructed as follows: In the rotating state, the battery is supplied with power. In the stopped state, the power supply from the battery is cut off.

4. The work vehicle according to claim 3, characterized in that: The stopped state includes a state in which the turning electric motor rotates at a speed less than the permissible rotation speed.

5. The work vehicle according to claim 3 or 4, characterized in that: When a predetermined time has elapsed after the start of the power supply from the battery, the power supply from the battery to the turning electric motor is interrupted.

6. The work vehicle according to claim 5, characterized in that: The rotation speed of the turning electric motor is gradually reduced within the predetermined time, so that the turning electric motor is restored to the stopped state.

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