Work vehicles

Abstract

To provide a work vehicle that can improve the efficiency of harvesting work by suppressing excessive load on the electric motor used for work. [Solution] Below the control unit (5), a first electric motor (30) that drives the harvesting device (4) and a second electric motor (40) that drives the front wheel (2) or rear wheel (3) are provided. A mode switch (26) for switching the length of the harvesting work time and an accelerator pedal (12) for increasing or decreasing the output rotation of the second electric motor (40) are provided. A first threshold (A1) for mode 1 with a long harvesting work time, a first threshold (C1) for mode 3 with a short harvesting work time, and a long harvesting work time are set in advance. A first threshold (B1) for Mode 2 is set for a short period of time, the first threshold (C1) for Mode 3 is set higher than the first threshold (A1) for Mode 1 and the first threshold (B1) for Mode 2, and the first threshold (B1) for Mode 2 is set higher than the first threshold (A1) for Mode 1. The controller (80) of the work vehicle reduces the output rotation of the second motor (40) when the load on the first motor (30) exceeds the first threshold (A1, B1, C1).

Description

Technical Field

[0001] The present invention relates to a work vehicle for mowing lawn grass.

Background Art

[0002] Conventionally, there is known a technique in which a working electric motor for driving a mowing work device for mowing lawn grass and a traveling electric motor for driving drive wheels are provided, and when an excessive load is applied to the working electric motor, the rotational output of the traveling electric motor is decelerated. (Patent Document 1)

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the means of Patent Document 1, since the upper limit of the rotational output of the working electric motor is determined for each mode of the mowing work, there has been pointed out a problem that the efficiency of the mowing work is reduced.

[0005] Therefore, an object of the present invention is to provide a work vehicle that can suppress an excessive load from being applied to the working electric motor and improve the efficiency of the mowing work.

Means for Solving the Problems

[0006] The present invention that has solved the above problems is as follows. That is, in the invention according to claim 1, a pair of left and right front wheels (2) and rear wheels (3) are provided on the lower side of the body frame (1), a mowing work device (4) for mowing lawn grass is provided on the front side of the body frame (1), a control unit (5) on which an operator rides is provided on the rear side of the mowing work device (4), and a grass collection container (7) for accommodating lawn grass is provided on the rear side of the control unit (5). In the work vehicle, Below the control unit (5), a first electric motor (30) for driving the harvesting device (4) and a second electric motor (40) for driving the front wheel (2) or rear wheel (3) are provided. A mode switch (26) for switching the length of the harvesting work time and an accelerator pedal (12) for increasing or decreasing the output rotation of the second electric motor (40) are provided. A first threshold (A1) for mode 1 with a long harvesting work time, a first threshold (C1) for mode 3 with a short harvesting work time, and an intermediate time between the long and short harvesting work times are pre-defined. A first threshold (B1) for Mode 2 is provided, the first threshold (C1) for Mode 3 is set higher than the first threshold (A1) for Mode 1 and the first threshold (B1) for Mode 2, and the first threshold (B1) for Mode 2 is set higher than the first threshold (A1) for Mode 1, and the controller (80) of the work vehicle is characterized in that when the load of the first motor (30) exceeds the first threshold (A1, B1, C1), it reduces the output rotation of the second motor (40).

[0007] The invention described in claim 2 is a work vehicle according to claim 1, wherein a second threshold (A2) for long-duration mode 1, a second threshold (B2) for medium-duration mode 2, and a second threshold (C2) for short-duration mode 3 are set in advance, and the controller (80) when the load of the first motor (30) is less than or equal to the first threshold (A1) for mode 1 and greater than the second threshold (A2), when the load of the first motor (30) is less than or equal to the first threshold (B1) for mode 2 and greater than the second threshold (B2), or when the load of the first motor (30) is less than or equal to the first threshold (C1) for mode 3 and greater than the second threshold (C2), the controller (80) reduces the output rotation of the second motor (40) when the fluctuation of the load of the first motor (30) is greater than a predetermined load fluctuation value, and maintains the output rotation of the second motor (40) when the fluctuation of the load of the first motor (30) is within the fluctuation value.

[0008] The invention described in claim 3 is a work vehicle according to claim 2, in which the second threshold (C2) of mode 3 is set higher than the second threshold (A2) of mode 1 and the second threshold (B2) of mode 2, and the second threshold (B2) of mode 2 is set higher than the second threshold (A2) of mode 1.

[0009] The invention described in claim 4 is a work vehicle according to claim 3, wherein the controller (80) increases or decreases the output rotation of the second motor (40) based on the amount the accelerator pedal (12) is pressed when the load of the first motor (30) is less than or equal to a second threshold (A2, B2, C2).

[0010] The invention described in claim 5 is a work vehicle according to claim 1, which can increase the output rotation of the first electric motor (30) to the maximum output rotation speed regardless of the mode 1 to 3.

[0011] The invention described in claim 6 is a work vehicle according to claim 1, wherein the mowing device (4) and the grass collection container (7) are connected by a chute (16), and the first electric motor (30) drives a blower (17) provided at the front of the chute (16). [Effects of the Invention]

[0012] According to the invention described in claim 1, a first electric motor (30) for driving the harvesting device (4) and a second electric motor (40) for driving the front wheel (2) or rear wheel (3) are provided below the control unit (5), a mode switch (26) for switching the length of the harvesting work time and an accelerator pedal (12) for increasing or decreasing the output rotation of the second electric motor (40) are provided, and a first threshold (A1) for mode 1 with a long harvesting work time, a first threshold (C1) for mode 3 with a short harvesting work time, and a first threshold (A1) for mode 2 with an intermediate harvesting work time between the long and short harvesting work times are predetermined. By setting a value (B1), the first threshold (C1) for Mode 3 is set higher than the first threshold (A1) for Mode 1 and the first threshold (B1) for Mode 2, and the first threshold (B1) for Mode 2 is set higher than the first threshold (A1) for Mode 1. When the load on the first motor (30) exceeds the first threshold (A1, B1, C1), the controller (80) of the work vehicle reduces the output rotation of the second motor (40), thereby suppressing excessive load on the first motor (30) and improving the efficiency of harvesting. In addition, it is possible to reduce battery power consumption and perform harvesting work for a longer period of time.

[0013] According to the invention described in claim 2, in addition to the effects of the invention described in claim 1, a second threshold (A2) for long-duration mode 1, a second threshold (B2) for medium-duration mode 2, and a second threshold (C2) for short-duration mode 3 are provided in advance. The controller (80) reduces the output rotation of the second motor (40) when the load of the first motor (30) is less than or equal to the first threshold (A1) for mode 1 and greater than the second threshold (A2), less than or equal to the first threshold (B1) for mode 2 and greater than the second threshold (B2), or less than or equal to the first threshold (C1) for mode 3 and greater than the second threshold (C2), if the fluctuation in the load of the first motor (30) is greater than a predetermined load fluctuation value, and maintains the output rotation of the second motor (40) when the fluctuation in the load of the first motor (30) is within the fluctuation value, thereby increasing the efficiency of harvesting work. Furthermore, it allows for longer harvesting hours by further reducing battery power consumption.

[0014] According to the invention described in claim 3, in addition to the effects of the invention described in claim 2, the second threshold (C2) of mode 3 is set higher than the second threshold (A2) of mode 1 and the second threshold (B2) of mode 2, and the second threshold (B2) of mode 2 is set higher than the second threshold (A2) of mode 1, so the efficiency of harvesting can be further increased. In addition, battery power consumption can be further suppressed, allowing harvesting work to be performed for an even longer period of time.

[0015] According to the invention described in claim 4, in addition to the effects of the invention described in any one of claims 1 to 3, the controller (80) increases or decreases the output rotation of the second motor (40) based on the amount the accelerator pedal (12) is pressed when the load of the first motor (30) is below the second threshold (A2, B2, C2), thereby reducing the processing load on the controller (80).

[0016] According to the invention described in claim 5, in addition to the effects of the invention described in claim 1, the output rotation of the first electric motor (30) can be increased to the maximum output rotation speed regardless of the mode 1 to 3, thereby further improving the efficiency of harvesting work.

[0017] According to the invention described in claim 6, in addition to the effects of the invention described in claim 1, the mowing device (4) and the grass collecting container (7) are communicated with each other by a chute (16), and a blower (17) provided at the front part of the chute (16) is driven by a first electric motor (30). Therefore, the mowed turf grass can be conveyed to the grass collecting container (7), and the retention of the turf grass in the chute (16) can be prevented.

Brief Description of the Drawings

[0018] [Figure 1] It is a perspective view of the work vehicle viewed from the front left side. [Figure 2] It is a perspective view of the front part of the electric chamber viewed from the rear left side. [Figure 3] It is a perspective view of the rear part of the electric chamber viewed from the rear left side. [Figure 4] It is a perspective view of the electric motor and the gear case viewed from the front left side. [Figure 5] It is a perspective view of the electric motor and the gear case viewed from the rear left side. [Figure 6] It is a rear view of the electric motor and the gear case. [Figure 7] It is a sectional view of the broken part of the left part of the gear case. [Figure 8] It is a transmission diagram of the output rotation of the electric motor. [Figure 9] It is a perspective view of the battery viewed from the rear left side. [Figure 10] It is a plan view of the battery mounted on the electric chamber. [Figure 11] It is a plan view of the electric motor and the inverter device. [Figure 12] It is a left side view of the electric motor and the inverter device. <00001​​​​​​​​​​​​This is a control method for the electric motor used for driving in Mode 1. [Figure 18] This is a control method for the electric motor used for driving in Mode 2. [Figure 19] This is a control method for the electric motor used for driving in Mode 3. [Figure 20] This is an explanatory diagram of the first and second thresholds for modes 1-3. [Modes for carrying out the invention]

[0019] As shown in Figure 1, the work vehicle has a pair of front wheels 2 on the lower front part of the machine frame 1, and a pair of rear wheels 3 on the lower rear part of the machine frame 1.

[0020] The front of the machine frame 1 is equipped with a mowing device 4 for cutting grass growing in the field, and the rear of the mowing device 4 is equipped with a control unit 5 where the operator sits. Behind the control unit 5 is a safety frame (rops) 6 for protecting the operator, and behind the safety frame 6 is equipped with a grass collection container 7 for storing the cut grass. Below the grass collection container 7 is an electric motor room 8 where the electric motor 30 and battery 60 for driving the mowing device 4 are located.

[0021] A steering column 10 supporting the steering wheel is provided in front of the cockpit of the control unit 5. A touch panel monitor displaying the output rotation speed of the electric motor 30 and other information is provided at the top of the steering column 10, and the lower part is fixed to the front of the floor.

[0022] A brake pedal 11 for reducing the rotational speed of the front wheels 2 is provided on the left side of the steering column 10 on the floor, and an accelerator pedal 12 for increasing or decreasing the output rotational speed of the electric motor 40 that drives the front wheels 2 is provided on the right side. The amount of depression of the accelerator pedal 12 is measured by an angle sensor 12S such as a potentiometer attached to its base.

[0023] The area above the front wheel 2 is covered by a fender 13, and a gear shift lever 14 for operating an inverter device 35 that increases or decreases the output rotation of the electric motor 30 is provided on the fender 13 located to the right of the driver's seat.

[0024] Furthermore, a control switch 25 for starting load control is provided behind the gear shift lever 14, and a mode switch 26 for setting the power consumption of the electric motor 30 and the maximum output rotation and angular acceleration of the electric motor 40 is provided to the left of the control switch 25.

[0025] The rear of the mowing device 4 and the front of the grass collection container 7 are connected by a chute 16 that extends in the front-to-back direction, and a blower 17 is provided in the middle of the chute 16 in the front-to-back direction to exhaust air into the chute 16.

[0026] A pair of link arms 18 are provided on the front of the left and right walls of the grass collection container 7. The front of each link arm 18 is pivotably fixed to the safety frame 6, and the safety frame 6 and the link arms 18 are connected by a lifting component 19 such as a hydraulic cylinder. The rear of the lower wall of the grass collection container 7 is resting on the horizontal frame 21A of the support frame 21, which will be described later. This allows the lifting component 19 to be driven to raise and lower the grass collection container 7.

[0027] As shown in Figures 2 and 3, the front motor room 8A of the motor room 8 is provided with an electric motor (the "first motor" in the claim) 30 and an electric motor (the "second motor" in the claim) 40, and the rear motor room 8B is provided with a battery 60 for storing power supplied to the electric motors 30 and the like.

[0028] In a plan view, the electric motor 30 is located to the left of the left-right centerline of the aircraft frame 1, and the electric motor 40 is located to the right of the left-right centerline of the aircraft frame 1. This allows for... By suppressing the weight difference between the weight applied to the left of the aircraft frame 1's lateral centerline and the weight applied to the right of the aircraft frame 1's lateral centerline, steering performance can be improved.

[0029] In a side view, a support frame 20 extending upward from the aircraft frame 1 is provided in the partition between the front motor compartment 8A and the rear motor compartment 8B, and a support frame 21 extending upward from the aircraft frame 1 is provided at the rear end of the rear motor compartment 8B.

[0030] The support frame 20 is formed by a left vertical frame 20L extending upward from the middle left portion of the aircraft frame 1, a right vertical frame 20R extending upward from the middle right portion of the aircraft frame 1, and a horizontal frame 20A extending in the left-right direction that connects the upper parts of the left vertical frame 20L and the right vertical frame 20R.

[0031] The support frame 21 is formed by a left longitudinal frame 21L extending upward from the left rear end of the aircraft frame 1, a right longitudinal frame 21R extending upward from the right rear end of the aircraft frame 1, a transverse frame 21A extending in the left-right direction and connecting the upper parts of the left longitudinal frame 21L and the right longitudinal frame 21R, and a transverse frame 21B extending in the left-right direction and connecting the intermediate parts of the left longitudinal frame 21L and the right longitudinal frame 21R. The left part of the transverse frame 21B extends to the left of the left longitudinal frame 21L, and the right part extends to the right of the right longitudinal frame 21R.

[0032] The middle section of the left vertical frame 20L and the left end of the horizontal frame 21B are connected by the left front-rear frame 22L, which extends in the front-rear direction, and the middle section of the right vertical frame 20R and the right end of the horizontal frame 21B are connected by the right front-rear frame 22R, which extends in the front-rear direction. This allows the rear of the battery 60 to be positioned above the drive shaft 46 of the rear wheel 3, preventing large deformations from occurring in the aircraft frame 1.

[0033] The upper part of the left vertical frame 20L and the middle part of the left vertical frame 23L located at the rear of the control unit 5 are connected by a left front-rear frame 24L that extends in the front-rear direction, and the upper part of the right vertical frame 20R of the support frame 20 and the middle part of the right vertical frame 23R located at the rear of the control unit 5 are connected by a right front-rear frame 24R that extends in the front-rear direction.

[0034] As shown in Figures 4 and 5, the motor 30 and motor 40 are in front of the motor 30 and motor 40. It is connected to a gear case 50 located on the side. The output rotation of the electric motor 30 is accelerated and decelerated within the gear case 50 before being transmitted to the output shaft 31 to which the harvesting work device 4 etc. is connected, the output shaft 32 to which the blower 17 etc. is connected, and the output shaft 33 to which the hydraulic pump 51 etc. is connected. The output rotation of the electric motor 40 is accelerated and decelerated within the gear case 50 before being transmitted to the output shaft 41 to which the front wheels 2 etc. are connected, and to the output shaft 42 to which auxiliary work equipment etc. is connected.

[0035] Output shaft 31 extends forward from the left middle of the gear case 50 in the front-to-back direction, and the front of output shaft 31 is connected to the harvesting device 4. Output shaft 32 extends forward from the front of the gear case 50, and the front of output shaft 32 is connected to the blower 17. Output shaft 33 extends rearward from the rear of the gear case 50, and the rear of output shaft 33 is connected to the hydraulic pump 51. A valve 52 is also provided on the upper part of the gear case 50.

[0036] Output shafts 41 and 42 extend in the front-rear direction along the right side of the gear case 50. The output rotation of output shaft 41 is transmitted to drive shaft 43 via differential gear 54 located inside the gear case 50. An insertion hole 50A extending in the left-right direction is provided in the middle of the gear case 50 in the front-rear direction, through which drive shaft 43 is inserted. Output shaft 42 extends rearward from the rear of the gear case 50.

[0037] The length of the electric motor 30 in the front-to-back direction is longer than the length of the electric motor 40 in the front-to-back direction. This allows the harvesting work device 4, which is constantly driven and subjected to a large load, to be driven smoothly.

[0038] As shown in Figure 6, the hydraulic pump 51 is positioned below the electric motors 30 and 40. This prevents air from entering the hydraulic pump 51 and suppresses air lock. Furthermore, the flexible piping 53A connecting the hydraulic pump 51 and the valve 52 is routed between the electric motors 30 and 40. This allows for effective use of the space formed between the electric motors 30 and 40.

[0039] As shown in Figure 7, the oil supplied to valve 52 is then supplied via valve 52 to clutch 55, located upstream of the transmission path of output shaft 31 in the gear case 50, and to clutch 56, located upstream of the transmission path of output shaft 32. This allows valve 52 to be driven to connect and disconnect clutch 55 and clutch 56.

[0040] The oil supplied from clutches 55 and 56 to valve 52 is returned to the gear case 50 through a flexible pipe 53B and a circulation port 50B formed at the top of the gear case 50. This allows the amount of oil in the gear case 50 to be maintained at a predetermined level.

[0041] As shown in Figure 8, the output rotation of the electric motor 30 is transmitted to the input shaft 57A of the gear case 50, and the output rotation of the input shaft 57A is transmitted to the rotating shaft 58A after being increased or decreased in speed.

[0042] The output rotation of the rotating shaft 58A is accelerated or decelerated before being transmitted to the output shaft 33, and the output rotation of the output shaft 33 is transmitted to the hydraulic pump 51. This allows the electric motor 30 to be driven, which in turn drives the hydraulic pump 51.

[0043] The output rotation of the rotating shaft 58A is accelerated or decelerated before being transmitted to the rotating shaft 58B, and the output rotation of the rotating shaft 58B is transmitted to the output shaft 31 via the clutch 55. The output rotation of the output shaft 31 is transmitted to the harvesting device 4. This allows the electric motor 30 to be driven, which in turn drives the harvesting device 4.

[0044] The output rotation of the rotating shaft 58A is accelerated or decelerated before being transmitted to the rotating shaft 58C, and the output rotation of the rotating shaft 58C is transmitted to the output shaft 32 via the clutch 56. The output rotation of the output shaft 32 is transmitted to the blower 17. This allows the electric motor 30 to be driven, which in turn drives the blower 17.

[0045] The output rotation of the electric motor 40 is transmitted to the input shaft 57B of the gear case 50, and the output rotation of the input shaft 57B is accelerated or decelerated before being transmitted to the output shafts 41 and 42.

[0046] The output rotation of the output shaft 41 is transmitted to the drive shaft 43 for the front wheels via the differential gear 54, and the output rotation of the drive shaft 43 is transmitted to the front wheels 2. This allows the electric motor 40 to be driven and the front wheels 2 to rotate. In addition, the output rotation of the output shaft 42 can also be transmitted to the rear wheels 3 via a clutch, auxiliary work equipment, or the differential gear.

[0047] As shown in Figure 9, the battery 60 is formed from four battery modules 60A. The upper parts of the four battery modules 60A are connected by a pair of left and right angle-shaped mounting frames 61 that extend in the front-to-back direction and are spaced apart in the left-to-right direction, and the lower parts are connected by a pair of left and right square pipe-shaped mounting frames 62 that extend in the front-to-back direction and are spaced apart in the left-to-right direction.

[0048] The front portion of the mounting frame 61 extends forward of the battery 60, and the rear portion extends backward of the battery 60. The mounting frame 62 extends from the front end to the rear end of the battery 60.

[0049] As shown in Figure 10, the front part of the mounting frame 61 is detachably fixed to the horizontal frame 20A of the support frame 20 by fastening members such as bolts, and the rear part is detachably fixed to the horizontal frame 21A of the support frame 21 by fastening members such as bolts.

[0050] The left mounting frame 62 is mounted on the left front / rear frame 22L, and the right mounting frame 62 is mounted on the right front / rear frame 22R.

[0051] The front and rear of the mounting frame 61 are formed with openings 61A through which a suspension hook can be inserted when replacing the battery 60. This allows the battery 60 to be easily attached to and detached from the support frame 20 and support frame 21, and the battery 60 to be easily replaced.

[0052] A radiator 65 for cooling the water used to cool the electric motor 30 and the like is provided on the outside of the left wall of the motor room 8, and a fan 66 for blowing outside air towards the motor room 8 is provided between the radiator 65 and the electric motor 30. In addition, a circular opening (not shown) is formed on the left wall of the motor room 8 in the area opposite the fan 66. This helps to suppress the temperature rise of the electric motor 30 and the like, and prevents the electric motor 30 and the like from malfunctioning.

[0053] An auxiliary battery 67 is provided on the outside of the right wall of the power room 8, opposite the radiator 65, to store power supplied to the monitor of the control unit 5. This helps to suppress the weight difference between the left and right sides of the work vehicle.

[0054] As shown in Figures 11 and 12, an inverter device 35 that drives the motor 30 is provided on the rear side of the motor 30 at a predetermined distance in the front-rear direction, and an inverter device 45 that drives the motor 40 is provided on the rear side of the motor 40 at a predetermined distance in the front-rear direction. Furthermore, the inverter devices 35 and 45 are provided on the front side of the battery 60 at a predetermined distance in the front-rear direction. This makes it easy to arrange the motors 30 and 40 and the inverter devices 35 and 45. In addition, the air blown from the fan 66 can pass through the gap between the motors 30 and 40 and the inverter devices 35 and 45, allowing for efficient cooling of the motors 30 and 40 and the inverter devices 35 and 45.

[0055] As shown in Figures 13 and 14, a power receiving port 70 for receiving power from a household power supply is provided on the upper rear side of the radiator 65.

[0056] An electrical unit 71 is located beneath the battery 60. The electrical unit 71 contains a charger that converts the power supplied to the power receiving port 70 from AC to DC and supplies it to the battery 60, and a converter that steps down the DC voltage supplied via the power distribution unit 73, etc., to the rated voltage of the auxiliary battery 67. The electrical unit 71 is detachably fixed to the underside of the left front and rear frame 22L and the right front and rear frame 22R.

[0057] A monitoring unit 72, which houses a monitoring device for monitoring the temperature and voltage of the battery 60, is provided on the front side of the battery 60. The monitoring unit 72 is detachably fixed to the upper part of the left front and rear frame 24L and the right front and rear frame 24R.

[0058] In a side view, it is preferable that the upper wall of the monitoring unit 72 be positioned below the mounting frame 61. This prevents the monitoring unit 72 from protruding above the mounting frame 61, allowing the height of the motor room 8 to be lower. As a result, the center of gravity of the grass collection container 7, which is located above the motor room 8, can be set at a lower position, allowing the work vehicle to run stably.

[0059] Below the monitoring unit 72, there is a power distribution unit 73 which houses terminal blocks for distributing the power supplied from the monitoring unit 72 to inverter devices 35 and 45, and converters of the electrical equipment unit 71, etc. The power distribution unit 73 is detachably fixed to the underside of the left front and rear frame 24L and the right front and rear frame 24R.

[0060] As shown in Figure 15, the controller 80 of the work vehicle is formed from a processing unit 81 consisting of a CPU and the like, a storage unit 82 consisting of ROM, RAM, a hard disk drive, flash memory and the like, and a communication unit 83 for data communication with the outside.

[0061] The processing unit 81 calculates output values ​​to be output to the inverter device 45 based on the amount the accelerator pedal 12 is pressed, calculates output values ​​to be output to the inverter device 45 based on the amount the gear shift lever 14 is operated, and calculates output values ​​to be output to the inverter device 35 based on the power consumption of the electric motor 30 which is preset for each mode selected by the mode switch 26.

[0062] The memory unit 82 saves the mode that was selected by the mode switch 26 immediately before the work vehicle stopped. This allows the vehicle to be restarted in the mode selected immediately before stopping without having to select a mode again with the mode switch 26.

[0063] The communication unit 83 transmits and receives data with a portable controller (not shown).

[0064] The input side of the controller 80 is connected via a predetermined input interface circuit to an angle sensor 12S that measures the amount the accelerator pedal 12 is pressed, a control switch 25 that increases or decreases the output rotation of the drive motor 40 based on the load of the work motor 30, a mode switch 26 that changes the output rotation of motors 30 and 40, and an inverter device 35 that drives the operation motor 30.

[0065] On the output side of the controller 80, an inverter device 35 that drives the work motor 30 and an inverter device 45 that drives the travel motor 40 are connected via a predetermined output interface circuit.

[0066] As shown in Figure 20, in this embodiment, modes 1 to 3 can be selected using the mode switch 26. Mode 1 is usually referred to as ECO mode, mode 2 as MIDDLE mode, and mode 3 as BOOST mode.

[0067] In Mode 1, the power consumption of the electric motor 30 is pre-set to low power consumption, i.e., for long periods of use. In Mode 2, the power consumption of the electric motor 30 is pre-set to medium power consumption, i.e., for medium periods of use. In Mode 3, the power consumption of the electric motor 30 is pre-set to high power consumption, i.e., for short periods of use. This allows for efficient mowing depending on the planting of the turfgrass in the field. For example, Mode 1 can be selected if the turfgrass is planted dispersed throughout the field, and Mode 3 can be selected if the turfgrass is planted densely in a specific part of the field. The settings for the electric motor 30 can also be set to maximum torque, maximum current, and maximum power.

[0068] As shown in Figure 16, power from the battery 60 is supplied to the controller 80 via power line P1, to the inverter devices 35 and 45 via power line P2, and to the electric motors 30 and 40 via power line P3.

[0069] The output value of the controller 80 is input to the inverter device 35 via signal line T1, and the output value of the inverter device 35 is input to the motor 30 via signal line T2. In addition, information such as the load applied to the motor 30 is input to the inverter device 35 via signal line T2, and input from the inverter device 35 to the controller 80 via signal line T1.

[0070] The output value of the controller 80 is input to the inverter device 45 via signal line T3, and the output value of the inverter device 45 is input to the electric motor 40 via signal line T4. In addition, information such as the load applied to the electric motor 40 is input to the inverter device 45 via signal line T4, and input from the inverter device 45 to the controller 80 via signal line T3. As a result, the operator can accurately predict the working time and travel distance that the electric motors 30 and 40 can use to harvest using the power of the battery 60 for each mode 1 to 3, and can efficiently plan the harvesting procedure.

[0071] As shown in Figure 17, in step S1, the processing unit 81 of the controller 80 determines whether the control switch 25, which increases or decreases the output rotation of the travel motor 40 based on the load of the work motor 30, has been activated. If it is determined that the control switch 25 has been activated, the process proceeds to step S2; if it is determined that the control switch 25 has not been activated, step S1 is repeated. This allows the operator to choose whether or not to increase or decrease the output rotation of the motor 40 based on the load of the motor 30.

[0072] In step S2, the processing unit 81 determines the state of the mode switch 26 that selects modes 1 to 3. If mode switch 26 is set to mode 1 (ECO mode), the process proceeds to step S3; if mode switch 26 is set to mode 2 (MIDDLE mode), the process proceeds to step S10; and if mode switch 26 is set to mode 3 (BOOST mode), the process proceeds to step S17.

[0073] In step S3, the processing unit 81 determines the current consumption value fed back from the inverter device 35, which indicates the load applied to the electric motor 30. Alternatively, the power consumption value or the output torque value of the electric motor 30 can be used as the determination criterion instead of the current value.

[0074] As shown in Figure 20, if the current consumption value exceeds a preset first threshold A1, the processing unit 81 proceeds to step S4, decelerates the vehicle speed of the work vehicle to a predetermined speed at a constant acceleration via the inverter device 45 and the electric motor 40, and returns to step S1. This reduces the load on the electric motor 30 and suppresses failure of the electric motor 30. In addition, the power supplied from the battery 60 to the electric motor 30 via the inverter device 35 is suppressed, allowing harvesting work to be performed for a long time in mode 1.

[0075] If the current consumption value is less than or equal to a preset first threshold A1 and greater than a second threshold A2, the processing unit 81 proceeds to step S5 and determines the magnitude of the fluctuation in the current consumption value fed back from the inverter device 35. If the fluctuation in the current consumption value exceeds a preset predetermined fluctuation value, the process proceeds to step S6, and if the fluctuation in the current consumption value is less than or equal to a predetermined predetermined fluctuation value, the process proceeds to step S7.

[0076] In step S6, the processing unit 81 reduces the vehicle speed of the work vehicle to a predetermined speed at a constant acceleration via the inverter device 45 and the electric motor 40, and returns to step S1 when the fluctuation in the current consumption value fed back from the inverter device 35 is less than or equal to a predetermined fluctuation value. This further reduces the load on the electric motor 30 and further suppresses failure of the electric motor 30. In addition, it further reduces the power supplied to the electric motor 30, allowing harvesting work to be performed for a longer period of time in mode 1.

[0077] In step S7, the processing unit 81 maintains the vehicle speed of the work vehicle via the inverter device 45 and the electric motor 40 and returns to step S1.

[0078] If the current consumption value is less than or equal to the preset second threshold A2, the processing unit 81 proceeds to step S8, reads the measured value input from the angle sensor 12S which measures the amount of depression of the accelerator pedal 12, and proceeds to step S9. Note that the measured value from the angle sensor 12S is not read in steps S4 and S5.

[0079] In step S9, the processing unit 81 increases or decreases the speed of the work vehicle via the inverter device 45 and electric motor 40 based on the measured value read from the angle sensor 12S, and returns to step S1. The first threshold A1, the second threshold A2, and the fluctuation value are input to the controller 80 via the monitor of the control unit 5.

[0080] As shown in Figure 18, in step S10, the processing unit 81 determines the current consumption value fed back from the inverter device 35, which indicates the load applied to the electric motor 30.

[0081] As shown in Figure 20, if the current consumption value exceeds a preset first threshold B1, the processing unit 81 proceeds to step S11, decelerates the vehicle speed of the work vehicle to a predetermined speed at a constant acceleration via the inverter device 45 and the electric motor 40, and returns to step S1. Note that the first threshold B1 is set to a load higher than the first threshold A1. This reduces the load on the electric motor 30 and suppresses failure of the electric motor 30. In addition, the power supplied from the battery 60 to the electric motor 30 via the inverter device 35 is suppressed, allowing harvesting work to be performed for a long time in mode 1.

[0082] The processing unit 81 proceeds to step S12 if the current consumption value is less than or equal to a preset first threshold B1 and greater than a second threshold B2, and determines the magnitude of the fluctuation in the current consumption value fed back from the inverter device 35. If the fluctuation in the current consumption value exceeds a preset predetermined fluctuation value, the process proceeds to step S13, and if the fluctuation in the current consumption value is less than or equal to a predetermined predetermined fluctuation value, the process proceeds to step S14. Note that the second threshold B2 is set to a load higher than the second threshold A2.

[0083] In step S13, the processing unit 81 reduces the vehicle speed of the work vehicle to a predetermined speed at a constant acceleration via the inverter device 45 and the electric motor 40, and returns to step S1 when the fluctuation in the current consumption value fed back from the inverter device 35 is less than or equal to a predetermined fluctuation value. This further reduces the load on the electric motor 30 and further suppresses failure of the electric motor 30. In addition, it further reduces the power supplied to the electric motor 30, allowing harvesting work to be performed for a longer period of time in mode 1.

[0084] In step S14, the processing unit 81 maintains the vehicle speed of the work vehicle via the inverter device 45 and the electric motor 40 and returns to step S1.

[0085] If the current consumption value is less than or equal to the preset second threshold B2, the processing unit 81 proceeds to step S15, reads the measured value input from the angle sensor 12S which measures the amount the accelerator pedal 12 is depressed, and proceeds to step S16. Note that the measured value from the angle sensor 12S is not read in steps S11 and S12.

[0086] In step S16, the processing unit 81 increases or decreases the speed of the work vehicle via the inverter device 45 and electric motor 40 based on the measured value of the angle sensor 12S, and returns to step S1. The first threshold B1, the second threshold B2, and the fluctuation value are input to the controller 80 via the monitor of the control unit 5.

[0087] As shown in Figure 19, in step S17, the processing unit 81 determines the current consumption value fed back from the inverter device 35, which indicates the load applied to the electric motor 30.

[0088] As shown in Figure 20, if the current consumption value exceeds a preset first threshold C1, the processing unit 81 proceeds to step S18, decelerates the vehicle speed of the work vehicle to a predetermined speed at a constant acceleration via the inverter device 45 and the electric motor 40, and returns to step S1. The first threshold C1 is set to a load higher than the first thresholds A1 and B1. This reduces the load on the electric motor 30 and suppresses failure of the electric motor 30. In addition, the power supplied from the battery 60 to the electric motor 30 via the inverter device 35 is suppressed, allowing harvesting work to be performed for a long time in mode 1.

[0089] The processing unit 81 proceeds to step S19 if the current consumption value is less than or equal to a preset first threshold C1 and greater than a second threshold C2, and determines the magnitude of the fluctuation in the current consumption value fed back from the inverter device 35. If the fluctuation in the current consumption value exceeds a preset predetermined fluctuation value, the process proceeds to step S20, and if the fluctuation in the current consumption value is less than or equal to a predetermined predetermined fluctuation value, the process proceeds to step S21. The second threshold C2 is set to a load higher than the second thresholds A2 and B2.

[0090] In step S20, the processing unit 81 reduces the vehicle speed of the work vehicle to a predetermined speed at a constant acceleration via the inverter device 45 and the electric motor 40, and returns to step S1 when the fluctuation in the current consumption value fed back from the inverter device 35 is less than or equal to a predetermined fluctuation value. This further reduces the load on the electric motor 30 and further suppresses failure of the electric motor 30. In addition, it further reduces the power supplied to the electric motor 30, allowing harvesting work to be performed for a longer period of time in mode 1.

[0091] In step S21, the processing unit 81 maintains the vehicle speed of the work vehicle via the inverter device 45 and the electric motor 40 and returns to step S1.

[0092] If the current consumption value is less than or equal to the preset second threshold C2, the processing unit 81 proceeds to step S22, reads the measured value input from the angle sensor 12S which measures the amount the accelerator pedal 12 is depressed, and proceeds to step S23. Note that the measured value from the angle sensor 12S is not read in steps S18 and S19.

[0093] In step S23, the processing unit 81 increases or decreases the speed of the work vehicle via the inverter device 45 and electric motor 40 based on the measured value of the angle sensor 12S, and returns to step S1. The first threshold C1, the second threshold C2, and the fluctuation value are input to the controller 80 via the monitor of the control unit 5. [Explanation of Symbols]

[0094] 1. Aircraft frame 2 Front wheels 3 Rear wheels 4 Reaping device 5. Control Unit 7 Grass collection container 12. Accelerator pedal 16 Shooter 17 Blower 26 Mode Switches 30 Electric motor (1st electric motor) 40 Electric motor (second electric motor) 80 Controllers A1 First threshold A2 Second threshold B1 First threshold B2 Second threshold C1 First threshold C2 Second threshold

Claims

1. In a work vehicle having a frame (1) with a pair of front wheels (2) and rear wheels (3) on the underside, a grass cutting device (4) for cutting grass on the front of the frame (1), a control unit (5) for the operator to sit on behind the grass cutting device (4), and a grass collection container (7) for storing grass behind the control unit (5), Below the control unit (5), a first electric motor (30) for driving the harvesting device (4) and a second electric motor (40) for driving the front wheel (2) or rear wheel (3) are provided. A mode switch (26) for switching the length of the harvesting work time and an accelerator pedal (12) for increasing or decreasing the output rotation of the second electric motor (40) are provided. A first threshold (A1) for Mode 1, where the harvesting work time is long, a first threshold (C1) for Mode 3, where the harvesting work time is short, and a first threshold (B1) for Mode 2, where the harvesting work time is intermediate between the long and short periods are set in advance. The first threshold (C1) of mode 3 is set higher than the first threshold (A1) of mode 1 and the first threshold (B1) of mode 2, and the first threshold (B1) of mode 2 is set higher than the first threshold (A1) of mode 1. The controller (80) of the work vehicle is characterized in that when the load on the first electric motor (30) exceeds a first threshold (A1, B1, C1), it reduces the output rotation of the second electric motor (40).

2. A second threshold (A2) for the long-duration mode 1, a second threshold (B2) for the medium-duration mode 2, and a second threshold (C2) for the short-duration mode 3 are set in advance. The controller (80) is configured such that when the load of the first motor (30) is less than or equal to the first threshold (A1) of mode 1 and greater than the second threshold (A2), when the load of the first motor (30) is less than or equal to the first threshold (B1) of mode 2 and greater than the second threshold (B2), or when the load of the first motor (30) is less than or equal to the first threshold (C1) of mode 3 and greater than the second threshold (C2), the controller (80) reduces the output rotation of the second motor (40) if the fluctuation in the load of the first motor (30) is greater than a predetermined load fluctuation value, and maintains the output rotation of the second motor (40) if the fluctuation in the load of the first motor (30) is within the predetermined fluctuation value.

3. The work vehicle according to claim 2, wherein the second threshold (C2) of mode 3 is set higher than the second threshold (A2) of mode 1 and the second threshold (B2) of mode 2, and the second threshold (B2) of mode 2 is set higher than the second threshold (A2) of mode 1.

4. The work vehicle according to claim 3, wherein the controller (80) increases or decreases the output rotation of the second motor (40) based on the amount the accelerator pedal (12) is pressed when the load of the first motor (30) is less than or equal to a second threshold (A2, B2, C2).

5. The work vehicle according to claim 1, which can increase the output rotation of the first electric motor (30) to the maximum output rotation speed regardless of the mode 1 to 3.

6. The work vehicle according to claim 1, wherein the mowing device (4) and the grass collection container (7) are connected by a chute (16), and the first electric motor (30) drives a blower (17) provided at the front of the chute (16).

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