Work vehicle

Abstract

To provide a work vehicle capable of preventing deterioration of a replacement component of an electric motor for driving a mowing device.SOLUTION: A work vehicle has: an operation section (6) on which an operator boards, provided above a machine body frame (1); and a first electric motor (40) for driving a mowing device (4) and a second electric motor (30) for driving rear wheels (3) provided beneath the operation section (6). A rotation speed of output rotation of the second electric motor (30) is reduced when a load of a predetermined value or more is applied to the first electric motor (40) for a predetermined set time or longer.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to a work vehicle for cutting grass in farm fields and the like. [Background technology]

[0002] Conventionally, a known technology for a work vehicle is to provide an electric motor behind the driver's seat to drive the rear wheels and an electric motor to drive a grass cutter, and to supply power from a battery located inside the bonnet (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2023-27497 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the method described in Patent Document 1, when a heavy load was applied to the grass-cutting device from dense grass, the temperature of the electric motor that drives the grass-cutting device would rise, which could cause premature deterioration of replacement parts for the motor.

[0005] SUMMARY OF THE PRESENT DISCLOSURE In view of the above, an object of the present invention is to provide a work vehicle that is capable of suppressing deterioration of replacement parts of the electric motor that drives the grass cutting device. [Means for solving the problem]

[0006] The present invention which has solved the above problems is as follows. That is, the invention described in claim 1 is a work vehicle having a pair of left and right front wheels (2) at the front of the lower side of a machine frame (1), a pair of left and right rear wheels (3) at the rear, and a grass cutting device (4) for cutting grass between the front wheels (2) and the rear wheels (3), This work vehicle is characterized in that a control section (6) on which an operator rides is provided above the body frame (1), a first electric motor (40) for driving the grass cutting device (4) and a second electric motor (30) for driving the rear wheels (3) are provided below the control section (6), and when a load equal to or greater than a predetermined value is applied to the first electric motor (40) for a preset period of time or longer, the rotational speed of the output rotation of the second electric motor (30) is reduced.

[0007] The invention described in claim 2 is the work vehicle described in claim 1, in which, when the load is large, the rotational speed of the output rotation of the second electric motor (30) is significantly reduced, and, when the load is small, the rotational speed of the output rotation of the second electric motor (30) is reduced to decelerate.

[0008] The invention described in claim 3 is the work vehicle described in claim 1 or 2, wherein, when the load becomes less than a predetermined value, the rotational speed of the output rotation of the second electric motor (30) is increased to the rotational speed of the output rotation before deceleration.

[0009] The invention described in claim 4 is the work vehicle described in claim 1, wherein, when a forward accelerator pedal (27) or a reverse accelerator pedal (28) of the steering section (6) is depressed, the deceleration of the rotational speed of the output rotation of the second electric motor (30) is regulated, and the rotational speed of the output rotation of the second electric motor (30) is increased or decreased depending on the amount of depression of the forward accelerator pedal (27) or the reverse accelerator pedal (28).

[0010] The invention described in claim 5 is the work vehicle described in claim 1, in which the load on the first electric motor (40) becomes equal to or greater than a predetermined value when the rotational speed of the output rotation of the first electric motor (40) becomes equal to or lower than a preset set rotation speed.

[0011] According to a sixth aspect of the present invention, a safety frame (7) for protecting an operator is provided behind the control unit (6), and a positioning device (11) for receiving information from a positioning satellite is provided on the safety frame (7), The work vehicle according to claim 1, wherein the mowing operation data (80) is generated, the mowing operation data (80) displaying sections (71-73) of different grass densities that apply a load to the first electric motor (40) on a travel route (75) of the work vehicle. Effect of the Invention

[0012] According to the invention described in claim 1, a control section (6) on which an operator rides is provided above the machine frame (1), and a first electric motor (40) for driving the grass cutting equipment (4) and a second electric motor (30) for driving the rear wheels (3) are provided below the control section (6). When a load equal to or greater than a predetermined value is applied to the first electric motor (40) for a preset period of time or longer, the rotation speed of the output rotation of the second electric motor (30) is reduced. This prevents a load equal to or greater than a predetermined value from being applied to the first electric motor (40) for driving the grass cutting equipment (4) for a long period of time, thereby suppressing a temperature rise in the first electric motor (40) and deterioration of replacement parts.

[0013] According to the invention of claim 2, in addition to the effect of the invention of claim 1, when the load is heavy, the rotation speed of the output rotation of the second electric motor (30) is significantly reduced, and when the load is light, the rotation speed of the output rotation of the second electric motor (30) is reduced, so that the temperature rise of the first electric motor (40) can be further suppressed and the deterioration of replacement parts can be further suppressed. Also, a decrease in the efficiency of the harvesting work can be prevented.

[0014] According to the invention as set forth in claim 3, in addition to the effects of the invention as set forth in claim 1 or 2, when the load becomes less than a predetermined value, the rotational speed of the output rotation of the second electric motor (30) is increased to the rotational speed of the output rotation before deceleration, so that the traveling speed of the work vehicle can be increased to the traveling speed before deceleration, thereby enabling efficient grass cutting work.

[0015] According to the invention recited in claim 4, in addition to the effects of the invention recited in claim 1, when the forward accelerator pedal (27) or the reverse accelerator pedal (28) of the steering section (6) is depressed, the deceleration of the rotational speed of the output rotation of the second electric motor (30) is regulated, and the rotational speed of the output rotation of the second electric motor (30) is increased or decreased depending on the amount of depression of the forward accelerator pedal (27) or the reverse accelerator pedal (28), so that the judgment of the worker steering the work vehicle is given priority and mowing work can be performed according to the work plan.

[0016] According to the invention recited in claim 5, in addition to the effect of the invention recited in claim 1, when the rotational speed of the output rotation of the first electric motor (40) falls to or below a preset rotation speed, it is determined that the load on the first electric motor (40) has reached a predetermined value or higher. This makes it possible to accurately measure the load on the first electric motor (40).

[0017] According to the invention described in claim 6, in addition to the effects of the invention described in any one of claims 1 to 5, a safety frame (7) for protecting the operator is provided behind the steering unit (6), a positioning device (11) for receiving information from a positioning satellite is provided on the safety frame (7), and mowing work data (80) is created that displays sections (71 to 73) of different turfgrass densities that apply a load to the first electric motor (40) on the travel path (75) of the work vehicle. Therefore, when mowing work is to be performed again in the same field, etc., the mowing work plan can be easily created by referring to the mowing work data (80). [Brief description of the drawings]

[0018] [Figure 1] FIG. [Diagram 2] FIG. 2 is a left side view of the work vehicle with the bonnet cover in an open position. [Diagram 3] FIG. [Figure 4] FIG. [Diagram 5] FIG. 2 is an explanatory diagram of an electric motor that drives the rear wheels and a working machine that drives the working machine. [Figure 6]FIG. 2 is an explanatory diagram of electrical components arranged under the cockpit. [Figure 7] FIG. 2 is a connection diagram of a controller. [Figure 8] 4 is an explanatory diagram of a method for increasing or decreasing the travel speed of a work vehicle. FIG. [Figure 9] FIG. 1 is an explanatory diagram showing the density of turfgrass superimposed on the travel path of a work vehicle. [Figure 10] 4 is an explanatory diagram of the load applied to the grass cutting device and the travel speed of the work vehicle. FIG. [Figure 11] FIG. 11 is an explanatory diagram of harvesting work data. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] As shown in FIG. 1, a work vehicle such as a riding lawnmower has a pair of left and right front wheels 2 provided at the front part of the underside of a body frame 1, a pair of left and right rear wheels 3 provided at the rear part of the underside of the body frame 1, and a grass cutting device 4 for cutting grass, etc. is provided between the front wheels 2 and the rear wheels 3.

[0020] A bonnet 5 in which a battery 15 is located is provided at the front upper part of the body frame 1, a control unit 6 on which the operator sits is provided behind the bonnet 5, a safety frame (ROPS) 7 for protecting the operator is provided behind the control unit 6, and a grass collection container 8 for storing cut grass is provided behind the safety frame 7.

[0021] As shown in Figures 2 and 3, the rear of the grass cutting device 4 and the front of the grass collection container 8 are connected by a chute 10 with a rectangular opening. In addition, a positioning device 11 such as a GPS antenna that receives work vehicle position information transmitted from a positioning satellite and a base station is attached to the top of the safety frame 7. This makes it easy to create work data that maps the travel speed and work load of the work vehicle, which will be described later, for each field selected based on the work vehicle's position information.

[0022] A battery 15 is stored inside the bonnet 5. A steering wheel 22 supported by a steering column 21 is provided in front of a driver's seat 20 of the control section 6, a blower lever 24 for activating a blower that conveys grass accumulated in the chute 10 toward a grass collection container is provided on a fender 23 on the left side of the driver's seat 20, and a lift lever 25 for raising and lowering the grass cutting device 4 is provided on a fender 23 on the right side. A brake pedal 26 is provided on the left side of the steering column 21, and a forward accelerator pedal 27 and a reverse accelerator pedal 28 are provided on the right side. A forward sensor 27S such as a potentiometer that measures the amount of depression of the forward accelerator pedal 27 is attached to the base of the forward accelerator pedal 27, and a reverse sensor 28S such as a potentiometer that measures the amount of depression of the reverse accelerator pedal 28 is attached to the base of the reverse accelerator pedal 28.

[0023] 4 and 5, an electric motor ("second electric motor" in claims) 30, such as a synchronous motor or an induction motor, that drives the rear wheels 3, and an electric motor ("first electric motor" in claims) 40 that drives the grass cutting device 4 are provided below the cockpit 20. The electric motor 30 is disposed at a position offset to the upper left side of the vehicle frame 1, and the output shaft of the electric motor 30 extends in the left-right direction. In addition, the electric motor 40 is disposed above the electric motor 30, and the output shaft of the electric motor 40 extends in the front-rear direction.

[0024] The output rotation output from the electric motor 30 is transmitted to a gear box 31 provided on the right side of the electric motor 30. The gear box 31 reduces the speed of the transmitted output rotation, increases the output torque, and switches the direction of rotation.

[0025] The output rotation output from the gear box 31 is transmitted to a drive shaft 33 extending in the left-right direction via a differential gear 32 formed by a differential gear or the like and provided at the bottom of the gear box 31. The output rotation output from the drive shaft 33 is transmitted to rear wheels 3 supported at both ends of the drive shaft 33.

[0026] The output rotation output from the electric motor 40 is transmitted to a gear box 42 provided above the left discharge passage 45L of the grass cutting device 4 via a universal joint 41 extending in the front-rear direction. The gear box 42 decelerates the transmitted output rotation to increase the output torque and switch the rotation direction.

[0027] The output rotation output from the gearbox 42 is transmitted from an output shaft extending in the vertical direction of the gearbox 42 to a left cutting blade (not shown) installed inside the left discharge passage 45L. The output rotation output from the gearbox 42 is also transmitted to a gearbox 44 provided above the right discharge passage 45R of the grass cutting device 4 via a connecting member 43 extending in the horizontal direction from an output shaft extending in the horizontal direction of the gearbox 42. The gearbox 44 reduces the speed of the transmitted output rotation to increase the output torque and switch the direction of rotation.

[0028] The output rotation output from the gear box 44 is transmitted from an output shaft extending in the vertical direction of the gear box 44 to a right cutting blade (not shown) installed within the right discharge passage 45R of the grass cutting device 4.

[0029] The discharge outlets of the left discharge passage 45L and the right discharge passage 45R are connected to the inlet of the chute 10. The output rotations of the left and right cutting blades are the same rotation speed and opposite directions, that is, in a plan view, the left cutting blade rotates clockwise and the right cutting blade rotates counterclockwise.

[0030] As shown in Fig. 6, an electrical equipment box 50 is provided between the cockpit 20 and the electric motor 30. A battery monitoring device 51 is disposed at the rear of the electrical equipment box 50, which monitors the temperature, charging state, voltage state, and short-circuit state of the internal cells of the battery 15, and a converter device 52 is disposed to the left of the battery monitoring device 51, which converts the high voltage supplied from the battery 15 into a low voltage that is supplied to sensors that measure the operating position of the blower lever 24, etc.

[0031] An auxiliary battery 53, such as a lead-acid battery, which supplies power to a meter panel that displays driving speed, etc., mounted on the top of the steering column, is located on the front left side of the battery monitoring device 51, and a driver 54 that operates the electric motors 30, 40 is located on the front right side.

[0032] The driver 54 is provided with inverter devices 55, 56 which convert the DC voltage supplied from the battery 15 into AC voltage and supply the three-phase AC voltage waveform to the electric motors 30, 40. In addition, the measurement value of a speed sensor 30S which measures the rotational speed of the output rotation of the electric motor 30 and the measurement value of a speed sensor 40S which measures the rotational speed of the output rotation of the electric motor 40 are fed back to the driver 54 and a controller 60 which will be described later.

[0033] <Controller connection diagram> As shown in FIG. 7, the controller 60 is formed from a processing unit 61 consisting of a CPU etc., a memory unit 62 consisting of a ROM, RAM, a hard disk drive, a flash memory etc., a timer 63, and a communication unit 64 for data communication with the outside.

[0034] The processing unit 61 reduces the rotation speed of the output rotation of the electric motor 30 that drives the rear wheels 3 when the rotation speed of the output rotation of the electric motor 40 that drives the grass cutting device 4 becomes slower than a predetermined rotation speed.

[0035] A preset rotation speed and a preset time are stored in the storage unit 62. The preset rotation speed and the preset time are inputted from the meter panel.

[0036] The timer 63 measures the elapsed time until the rotation speed of the output rotation of the electric motor 40 becomes slower than a predetermined rotation speed.

[0037] The communication unit 64 transmits and receives information to and from an external portable controller, etc.

[0038] A forward sensor 27S for measuring the amount of depression of the forward accelerator pedal 27, a reverse sensor 28S for measuring the amount of depression of the reverse accelerator pedal 28, a speed sensor 30S for measuring the rotational speed of the output rotation of the electric motor 30, and a speed sensor 40S for measuring the rotational speed of the output rotation of the electric motor 40 are connected to the input side of the controller 60 via a predetermined input interface circuit.

[0039] An inverter device 54A connected to the electric motor 30 and an inverter device 54B connected to the electric motor 40 are connected to the output side of the controller 60 via a predetermined output interface circuit.

[0040] <Method of increasing or decreasing the travel speed of a work vehicle> As shown in Fig. 8, in step S1, the processing unit 61 of the controller 60 of the work vehicle judges the load from grass or the like applied to the grass cutting device 4. If the measured value of the speed sensor 40S, which measures the rotation speed of the output rotation of the electric motor 40, is equal to or lower than the set rotation speed, the process proceeds to step S2, and if the measured value of the speed sensor 40S is higher than the set rotation speed, step S1 is repeated. Note that the surface temperature of the electric motor 40 can be used instead of the rotation speed of the output rotation of the electric motor 40, and the process can proceed to step S2 when the surface temperature of the electric motor 40 is equal to or higher than a preset surface temperature, and return to step S1 when the surface temperature of the electric motor 40 is lower than the set surface temperature.

[0041] As shown in Fig. 9, when the work vehicle is traveling in a section 71 of a farm field 70 where the grass density is high, the load on the grass cutter 4 is large and the output rotation speed of the motor 40 is slower than the set rotation speed, and when the work vehicle is traveling in a section 72 where the grass density is low, the load on the grass cutter 4 is small and the output rotation speed of the motor 40 is faster than the set rotation speed. When the work vehicle is traveling in a section 73 where the grass density is medium, the load on the grass cutter 4 is within a predetermined range and the output rotation speed of the motor 40 is approximately the same as the set rotation speed. The diagonal lines in the sections 71 to 73 indicate the grass density, and the dotted lines indicate the travel route 75 of the work vehicle.

[0042] In step S2, the processing unit 61 determines the time that the load has been applied to the grass mowing device 4. If the time that the load has been applied to the grass mowing device 4 is equal to or longer than the set time, the process proceeds to step S3, and if the time that the load has been applied to the grass mowing device 4 is less than the set time, the process returns to step S1. This prevents the control system from becoming unstable, and makes it possible to maintain the travel speed of the work vehicle at a low speed, as shown in FIG.

[0043] In step S3, the processing unit 61 lowers the frequency of the three-phase AC voltage waveform of the inverter device 55 that supplies power to the electric motor 30 that drives the rear wheels 3, decelerates the rotation speed of the output rotation of the electric motor 30, and proceeds to step S4. As a result, when the load on the grass cutting device 4 is greater than a predetermined load, the travel speed of the work vehicle is decelerated to reduce the load on the grass cutting device 4, suppress heat generation in the electric motor 40, and improve the durability of the electric motor 40.

[0044] The rotation speed of the output rotation of the electric motor 30 is decelerated based on an increase or decrease value obtained by dividing the rotation speed of the output rotation of the electric motor 40 by a set rotation speed. For example, when the increase or decrease value of the electric motor 40 is 0.9 to 1, the rotation speed of the output rotation of the electric motor 30 is decelerated to 0.9 with respect to the rotation speed of the output rotation of the electric motor 30 before deceleration, when the increase or decrease value of the electric motor 40 is 0.8 to 0.9, the rotation speed of the output rotation of the electric motor 30 is decelerated to 0.8 with respect to the rotation speed of the output rotation of the electric motor 30 before deceleration, and when the increase or decrease value of the electric motor 40 is 0.7 to 0.8, the rotation speed of the output rotation of the electric motor 30 is decelerated to 0.7 with respect to the rotation speed of the output rotation of the electric motor 30 before deceleration. As a result, when a large load is applied to the motor 40, the output speed of the output rotation of the motor 30 is significantly reduced to prevent damage to the motor 40, and when a small load is applied to the motor 40, the output speed of the output rotation of the motor 30 is slightly reduced to prevent a decrease in the efficiency of the mowing work.

[0045] In step S4, the processing unit 61 determines whether or not the operator is depressing the forward accelerator pedal 27. If the forward sensor 27S attached to the base of the forward accelerator pedal 27 does not measure the predetermined amount of depression, the process proceeds to step S5, and if the forward sensor 27S measures the predetermined amount of depression, the process proceeds to step S8. This allows the determination of the operator steering the front wheels 2 to be given priority.

[0046] In step S5, the processing unit 61 determines whether or not the operator is depressing the reverse accelerator pedal 28. If the reverse sensor 28S attached to the base of the reverse accelerator pedal 28 does not measure the predetermined amount of depression, the process proceeds to step S6, and if the reverse sensor 28S measures the predetermined amount of depression, the process proceeds to step S8. This allows the determination of the operator steering the front wheels 2 to take precedence.

[0047] In step S6, the processing unit 61 determines the load applied to the grass cutting device 4. If the measurement value of the speed sensor 40S, which measures the rotational speed of the output rotation of the electric motor 40, exceeds the set rotational speed, the process proceeds to step S7, and if the measurement value of the speed sensor 40S is equal to or lower than the set rotational speed, the process returns to step S2.

[0048] In step S7, the processing unit 61 increases the frequency of the three-phase AC voltage waveform of the inverter device 55 that supplies power to the electric motor 30 that drives the rear wheels 3, increases the rotation speed of the output rotation of the electric motor 30, and proceeds to step S1. As a result, when the load applied to the grass cutting device 4 falls within a predetermined range, the travel speed of the work vehicle can be increased to quickly cut the grass.

[0049] In step S8, the processing unit 61 increases or decreases the frequency of the three-phase AC voltage waveform of the inverter device 55 that supplies power to the electric motor 30 in response to the forward accelerator pedal 27 or the reverse accelerator pedal 28, and then returns to step S1. This allows the mowing work to proceed based on the work plan of the worker who is actually performing the mowing work.

[0050] <Storage of harvesting data> As shown in Fig. 11, during mowing work, the processing unit 61 creates mowing work data 80 that overlaps the field 70 and the load applied to the mower 4 on the travel route traveled by the work vehicle, i.e., the sections 71-73 with different grass densities, based on information received from the positioning device 11 by the communication unit 64, and stores the data in the memory unit 62. This makes it possible to easily plan the mowing work by reading out the mowing work data 80 when mowing work is to be performed again. The mowing work data 80 can also store the output rotation speed and surface temperature of the electric motors 30, 40. [Explanation of symbols]

[0051] 1 Aircraft frame 2 Front wheels 3 Rear wheel 4 Grass cutting equipment 6. Control Unit 7 Safety Frame 11 Positioning device 27 Forward accelerator pedal 28 Reverse accelerator pedal 30 Electric motor (second electric motor) 40 Electric motor (1st electric motor) 71 plots 72 plots 73 plots 75 Travel route 80 Harvesting data

Claims

1. A work vehicle having a pair of left and right front wheels (2) at the front of the lower side of a machine frame (1), a pair of left and right rear wheels (3) at the rear, and a grass cutting device (4) for cutting grass between the front wheels (2) and the rear wheels (3), A control section (6) on which an operator rides is provided above the machine frame (1), and a first electric motor (40) for driving the grass cutting device (4) and a second electric motor (30) for driving the rear wheels (3) are provided below the control section (6); A work vehicle characterized in that, when a load equal to or greater than a predetermined value is applied to the first electric motor (40) for a preset period of time or longer, the rotational speed of the output rotation of the second electric motor (30) is reduced.

2. 2. The work vehicle according to claim 1, wherein when the load is large, the rotational speed of the output rotation of the second motor (30) is significantly reduced, and when the load is small, the rotational speed of the output rotation of the second motor (30) is reduced to reduce the speed.

3. 3. The work vehicle according to claim 1, wherein when the load becomes less than a predetermined value, the rotational speed of the output rotation of the second electric motor (30) is increased to the rotational speed of the output rotation before deceleration.

4. 2. The work vehicle according to claim 1, wherein, when a forward accelerator pedal (27) or a reverse accelerator pedal (28) of the steering section (6) is depressed, a deceleration of the rotational speed of the output rotation of the second electric motor (30) is regulated, and the rotational speed of the output rotation of the second electric motor (30) is increased or decreased depending on the amount of depression of the forward accelerator pedal (27) or the reverse accelerator pedal (28).

5. 2. The work vehicle according to claim 1, wherein the load on the first electric motor is determined to be equal to or greater than a predetermined value when the rotational speed of the output rotation of the first electric motor falls below a preset rotational speed.

6. A safety frame (7) for protecting an operator is provided behind the control unit (6), and a positioning device (11) for receiving information from a positioning satellite is provided on the safety frame (7); 2. A work vehicle according to claim 1, wherein mowing operation data (80) is created that displays sections (71-73) of different grass densities that apply a load to the first electric motor (40) on a travel route (75) of the work vehicle.

Images