Electric work vehicle and charging method

Abstract

To provide an electric work vehicle which is chargeable with inexpensive constitution without selecting a place.SOLUTION: An electric work vehicle includes: a battery device 4 for storing power; a motor generator M which is connected to the battery device 4 so as to be supplied with power; a power transmission device having a power output shaft for transmitting power from the motor generator M; and a control device capable of switching between a first mode of driving the motor generator M by the power stored in the battery device 4, and a second mode of rotating the motor generator M by power of a driving source 5 connected to the power output shaft and allowing the motor generator M to generate regenerative power, and charging the battery device 4 by the regenerative power.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an electric work vehicle and a charging method. [Background technology]

[0002] For example, the electric work vehicle (referred to as an "electric work machine" in the document) disclosed in Patent Document 1 is equipped with a power storage device (referred to as a "battery" in the document) that stores electricity, and a motor (referred to as an "electric motor" in the document) that can be driven based on the electricity stored in the power storage device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-110893 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the power stored in the power storage device runs out, the power storage device needs to be recharged. However, if the work area is far from the charging facility, traveling to the charging location can be a burden. Furthermore, while it is possible to prepare a portable charging device to enable charging in the work area, portable charging devices are often expensive.

[0005] An object of the present invention is to provide an electric work vehicle and a charging method that have an inexpensive configuration and can be charged anywhere. [Means for solving the problem]

[0006] The electric work vehicle according to the present invention comprises a power storage device for storing electric power, a motor generator electrically connected to the power storage device, and a power generating unit for generating power from the motor generator. To the outsidea power transmission device having a power output shaft for transmitting power; a first mode in which the motor generator is driven by the electric power stored in the power storage device; and a second mode in which the motor generator is driven by the electric power stored in the power storage device. external a control device that can switch between a first mode and a second mode in which, when the motor generator is rotated by the power of a drive source, regenerative power is generated in the motor generator and the regenerative power is used to charge the power storage device. The control device changes the regenerative torque of the motor generator so that it becomes larger as time passes from the start of the second mode until a preset time has passed, and maintains the changed regenerative torque after the preset time has passed. It is characterized by the following.

[0007] According to the present invention, a drive source is connected to the power output shaft, and the drive source rotates the motor generator via the power output shaft, thereby generating regenerative power in the motor generator and charging the power storage device. In other words, the power storage device can be charged by generating power using the motor generator, which is normally driven for work. This realizes a less expensive configuration compared to a configuration in which a dedicated portable charging device is provided. Furthermore, the drive source may be of any configuration as long as it can be connected to the power output shaft. Therefore, for example, a drive source that can be easily prepared in the work area can be used as the drive source. This allows the power storage device to be charged anywhere, compared to a configuration in which charging is performed using charging equipment. Furthermore, as the regenerative torque increases, a large load is placed on the drive source. Therefore, if the regenerative torque increases suddenly, a sudden load is placed on the drive source, which may cause the drive source to suddenly decrease in drive speed or stall. This configuration makes it possible to gradually increase the regenerative torque of the motor generator. This reduces the risk of the drive source suddenly decreasing in drive speed or stalling. In this way, the present invention makes it possible to realize an electric work vehicle that has an inexpensive configuration and can be charged anywhere.

[0008] The present invention may also be a charging method for charging an electric storage device mounted on an electric work vehicle. In this case, the charging method includes charging the electric storage device with power from a motor generator electrically connected to the electric storage device. To the outside On the power output shaft of the power transmission device external a step of connecting a driving source, and causing the driving source to rotate the motor generator via the power transmission device; The regenerative power setting is changed so that it increases as time passes from the start until a preset time has elapsed. The motor generator generates regenerative power. and after the preset time has elapsed, the regenerative power is maintained after the preset time has elapsed. and charging the power storage device with the regenerated power.

[0009]

[0010]

[0011] In the present invention, it is preferable that the control device sets the regenerative torque to zero at the timing of starting the second mode.

[0012] With this configuration, when the control mode of the control device is switched to the second mode, the motor generator first rotates without load, thereby avoiding the risk of a sudden load being applied to the drive source.

[0013] In the present invention, a voltage detection unit is provided that detects the output voltage of the storage device, and it is preferable that, in the second mode, when the output voltage of the storage device exceeds a predetermined first threshold, the control device controls the motor generator so that the regenerative power is smaller than the regenerative power when the output voltage of the storage device reaches the first threshold.

[0014] This configuration prevents the power storage device from being overcharged.

[0015] In the present invention, a temperature detection unit is provided that detects the heat generation temperature of the storage device, and it is preferable that, in the second mode, when the heat generation temperature exceeds a predetermined second threshold, the control device controls the motor generator so that the regenerative power is smaller than the regenerative power when the heat generation temperature reaches the second threshold.

[0016] This configuration suppresses the heat generation temperature in the power storage device.

[0017] In the present invention, the power output shaft is preferably a PTO shaft that can be connected to an input shaft of a working device.

[0018] In this configuration, the power output shaft is the PTO shaft. Therefore, the PTO shaft also serves as the shaft that receives power from the drive source and rotates the motor generator. This enables an inexpensive configuration that allows the power storage device to be charged anywhere. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 2 is a left side view of the electric tractor. [Figure 2] FIG. 2 is a left side view showing the arrangement of an inverter and the like. [Figure 3] FIG. 2 is a diagram illustrating a flow of power transmission. [Figure 4] FIG. 2 is a block diagram showing the control configuration of the electric work vehicle. [Figure 5] 4 is a graph showing the heat temperature of the battery device, the voltage of the battery device, the regenerative torque of the motor generator, and the rotation speed of the motor generator when the motor generator generates electricity. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0020] An embodiment of the present invention will be described with reference to the drawings. In the following description, unless otherwise specified, the direction of the arrow "F" in the drawings will be referred to as "front," the direction of the arrow "B" as "rear," the direction of the arrow "L" as "left," and the direction of the arrow "R" as "right." Furthermore, the direction of the arrow "U" in the drawings will be referred to as "up," and the direction of the arrow "D" as "down."

[0021] [Overall configuration of the electric work vehicle] The electric work vehicle of this embodiment will be described below. An electric tractor is shown as an example of the electric work vehicle in Figure 1. As shown in Figure 1, the electric tractor has left and right front wheels 10, left and right rear wheels 11, and a cover member 12.

[0022] The electric tractor also includes a machine frame 2 and a driving section 3. The machine frame 2 is supported by left and right front wheels 10 and left and right rear wheels 11.

[0023] The cover member 12 is disposed at the front of the vehicle body, and the driving section 3 is provided behind the cover member 12. In other words, the cover member 12 is disposed in front of the driving section 3.

[0024] The driver's section 3 has a protective frame 30 , a seat 31 , and a steering wheel 32 . A driver can sit in the seat 31. This allows the driver to get on the driving section 3. The left and right front wheels 10 are steered by operating the steering wheel 32. The driver can perform various driving operations in the driving section 3.

[0025] The electric tractor is equipped with a battery device 4. The cover member 12 is configured to be swingable about an opening / closing axis Q that extends in the left-right direction of the vehicle body. This allows the cover member 12 to be opened and closed. When the cover member 12 is in a closed state, the battery device 4 is covered by the cover member 12. The battery device 4 corresponds to the "electricity storage device" of the present invention.

[0026] As shown in FIG. 2, the electric tractor includes a converter 14 and a motor generator M. The battery device 4 supplies power to the converter 14. The converter 14 converts DC power from the battery device 4 into AC power and supplies it to the motor generator M. The motor generator M is then driven by the AC power supplied from the converter 14. In other words, the motor generator M is driven by consuming the power stored in the battery device 4.

[0027] Although details will be described later, the motor generator M in this embodiment generates electricity when it receives kinetic energy from an external source and rotates. When the motor generator M is used as a power generator, the converter 14 converts the AC power generated by the motor generator M into DC power and supplies it to the battery device 4. This charges the battery device 4.

[0028] 2 and 3, the electric tractor includes a hydrostatic continuously variable transmission 15 and a transmission 16. As shown in Fig. 3, the hydrostatic continuously variable transmission 15 includes a hydraulic pump 15a and a hydraulic motor 15b.

[0029] The hydraulic pump 15a is driven by rotational power from the motor generator M. When the hydraulic pump 15a is driven, the rotational power is output from the hydraulic motor 15b. The hydrostatic continuously variable transmission 15 is configured so that the speed of the rotational power is changed between the hydraulic pump 15a and the hydraulic motor 15b. The hydrostatic continuously variable transmission 15 is also configured so that the gear ratio can be changed continuously.

[0030] The rotational power output from the hydraulic motor 15 b is transmitted to the transmission 16 . The rotational power transmitted to the transmission 16 is changed in speed by a gear-type speed change mechanism of the transmission 16 and distributed to the left and right front wheels 10 and the left and right rear wheels 11. In this way, the left and right front wheels 10 and the left and right rear wheels 11 are driven.

[0031] 2 and 3, the electric tractor includes a mid PTO shaft 17, a rear PTO shaft 18, and a front PTO shaft 20. A first clutch 17a is interposed between the motor generator M and the mid PTO shaft 17. A second clutch 18a is interposed between the motor generator M and the rear PTO shaft 18. A third clutch 20a is interposed between the motor generator M and the front PTO shaft 20.

[0032] The first clutch 17a and the second clutch 18a function as PTO clutches. Each of the first clutch 17a and the second clutch 18a is configured to be able to change its state between an ON state in which power is transmitted and a OFF state in which power is not transmitted. When the first clutch 17a is in the ON state, rotational power is transmitted from the motor generator M to the mid PTO shaft 17. The mid PTO shaft 17 corresponds to the "power output shaft" in this invention. Furthermore, the mid PTO shaft 17 and the first clutch 17a correspond to the "power transmission device" having a power output shaft that transmits power from the motor generator M in this invention.

[0033] Furthermore, when the second clutch 18a is engaged, rotational power is transmitted from the motor generator M to the rear PTO shaft 18. The rear PTO shaft 18 corresponds to the "power output shaft" in the present invention. Furthermore, the rear PTO shaft 18 and the second clutch 18a correspond to the "power transmission device" having a power output shaft that transmits power from the motor generator M in the present invention. Additionally, when the third clutch 20a is engaged, rotational power is transmitted from the motor generator M to the front PTO shaft 20. The front PTO shaft 20 corresponds to the "power output shaft" in the present invention. Furthermore, the front PTO shaft 20 and the third clutch 20a correspond to the "power transmission device" having a power output shaft that transmits power from the motor generator M in the present invention.

[0034] In this way, the rotational power output from the motor generator M is distributed to the hydraulic pump 15a, the mid PTO shaft 17, the rear PTO shaft 18, and the front PTO shaft 20. This causes the mid PTO shaft 17, the rear PTO shaft 18, and the front PTO shaft 20 to rotate. In other words, the motor generator M consumes the power stored in the battery device 4 to drive at least one of the traveling device and the working device.

[0035] If a working device is connected to the mid PTO shaft 17, the rear PTO shaft 18, or the front PTO shaft 20, the working device is driven by the rotational power of the mid PTO shaft 17, the rear PTO shaft 18, or the front PTO shaft 20. For example, as shown in FIG. 2 , in this embodiment, a brush cutter 19, as an example of a working device, is connected to the mid PTO shaft 17. The brush cutter 19 is driven by the rotational power of the mid PTO shaft 17.

[0036] [Controller configuration] As shown in Fig. 4, the control configuration of the motor generator M includes a control device 34 that controls the drive of the motor generator M, and a converter 14. The control device 34 is a core element of the control system of the electric work vehicle, and is configured as a collection of multiple ECUs. The control device 34 is connected to the converter 14 via a CAN (Controller Area Network) type signal harness 35 so that data can be communicated therebetween.

[0037] The control device 34 outputs a command signal to the converter 14 in response to a command from an accelerator device (not shown). The converter 14 adjusts the power (voltage value, frequency, current value, etc.) supplied from the battery device 4 to the motor generator M in response to the command signal from the control device 34, thereby controlling the output of the motor generator M.

[0038] The battery device 4 is, for example, a lithium ion battery. Although not shown, the battery device 4 is configured by stacking a large number of small, low-voltage unit cells. The output voltage of the battery device 4 is, for example, 250 volts. The unit cells are housed in a storage case. These unit cells are sealed in the storage case.

[0039] The temperature detection unit 36 ​​detects the heat temperature of the battery device 4. The value detected by the temperature detection unit 36 ​​is sent to the control device 34. The temperature detection unit 36 ​​may be a part of the battery device 4.

[0040] The voltage detection unit 37 detects the output voltage of the battery device 4. The value detected by the voltage detection unit 37 is sent to the control device 34. The voltage detection unit 37 may be a part of the converter 14 or a part of the battery device 4.

[0041] In this embodiment, the control device 34 has multiple control modes. The multiple control modes include a first mode and a second mode. In the first mode, the control device 34 drives the motor generator M using power stored in the battery device 4. When the control mode of the control device 34 is the second mode, when the motor generator M receives external kinetic energy and rotates, the control device 34 causes the motor generator M to generate regenerative power and charges the battery device 4 with this regenerative power. In other words, the control device 34 is switchable between the first mode and the second mode.

[0042] The switching operation device 38 receives a manual operation for switching the control mode of the control device 34. The control device 34 can be switched between a first mode and a second mode based on the manual operation of the switching operation device 38.

[0043] 1 and 2, for example, when the output shaft 5A of the drive source 5 is connected to the rear PTO shaft 18, the rear PTO shaft 18 can be rotated by the power of the drive source 5. The drive source 5 may be, for example, an engine, an electric motor, a hydraulic motor, or a power take-off shaft of another vehicle.

[0044] When the output shaft 5A of the drive source 5 is connected to the rear PTO shaft 18 and the first clutch 17a is engaged, the motor generator M is rotated by the power of the drive source 5, and the motor generator M is capable of generating electricity. At this time, if the control mode of the control device 34 is the second mode, the battery device 4 is charged by the regenerative power of the motor generator M.

[0045] In other words, the "power output shaft" of the present invention is the rear PTO shaft 18 that can be connected to the input shaft of the working device, and the rear PTO shaft 18 also serves as the shaft that receives power from the drive source 5 and rotates the motor generator M. This enables a configuration that allows charging anywhere at low cost.

[0046] [Regenerative control based on the second mode] A configuration in which the control device 34 controls the regenerative power of the motor generator M based on the second mode will be described with reference to the time chart of Fig. 5. The horizontal axis in Fig. 5 represents time, and the timing at which the control device 34 starts regenerative control of the motor generator M based on the second mode is defined as the zero value on the time axis. In addition, in the embodiment illustrated in Fig. 5, the drive source 5 rotates at a constant speed, and the rotor of the motor generator M rotates at a constant speed. That is, in the embodiment illustrated in Fig. 5, the motor generator M rotates at a constant speed.

[0047] The control device 34 sets the regenerative torque of the motor generator M to zero at the timing when regenerative control of the motor generator M is started. The regenerative current is proportional to the regenerative torque. Therefore, the motor generator M initially rotates with no load. At this timing, no regenerative power is generated from the motor generator M, and the regenerative current is also zero. In this way, the control device 34 sets the regenerative torque of the motor generator M to zero at the timing when the second mode starts.

[0048] From zero on the time axis to timing T1 shown in FIG. 5, the regenerative torque of the motor generator M gradually increases. That is, the control device 34 changes the setting of the regenerative torque of the motor generator M so that it increases as time passes from the start of the second mode until the preset timing T1 has elapsed. At this time, the rotation speed of the drive source 5 is likely to decrease due to the regenerative load of the motor generator M. For this reason, constant speed control of the drive source 5 is performed so that the rotation speed of the drive source 5 is also maintained constant. In this way, by the control device 34 gradually applying a regenerative load to the motor generator M, stalling of the drive source 5 is less likely to occur, and the rotation speed of the drive source 5 is more likely to be maintained constant.

[0049] The regenerated power generated by the rotation of the motor generator M is AC power and is input to the converter 14. The converter 14 converts the AC power generated by the rotation of the motor generator M into DC power and supplies it to the battery device 4. The voltage detection unit 37 detects the output voltage of the battery device 4.

[0050] In this embodiment, the control device 34 controls the regenerative torque so that the output voltage of the battery device 4 is maintained at, for example, a rated voltage or less. At timing T2 shown in FIG. 5, the output voltage of the battery device 4 exceeds the voltage threshold VT. The voltage threshold VT is lower than the rated voltage of the battery device 4. Therefore, the control device 34 reduces the regenerative torque of the motor generator M at timing T2. In this way, in the second mode, when the output voltage of the battery device 4 exceeds the preset voltage threshold VT, the control device 34 controls the motor generator M so that the regenerative power is smaller than the regenerative power when the output voltage of the battery device 4 reaches the voltage threshold VT. The voltage threshold VT corresponds to the "first threshold" of the present invention.

[0051] The battery 4 generates heat from its internal unit cells as it is charged. The temperature of this heat is detected by the temperature detection unit 36. In this embodiment, the control device 34 controls the regenerative torque so that the heat temperature of the battery 4 is maintained at or below the temperature threshold HT. At timing T3 shown in FIG. 5, the heat temperature of the battery 4 exceeds the temperature threshold HT. Therefore, the control device 34 reduces the regenerative torque of the motor generator M at timing T3. In this way, in the second mode, when the heat temperature of the battery 4 exceeds the preset temperature threshold HT, the control device 34 controls the motor generator M so that the regenerative power is smaller than the regenerative power when the heat temperature reaches the temperature threshold HT. The temperature threshold HT corresponds to the "second threshold" of the present invention.

[0052] 5, when the heat generation temperature of the battery 4 exceeds the temperature threshold value HT, the control device 34 may change the regenerative torque of the motor generator M to zero and wait for the battery 4 to cool down. Then, when the heat generation temperature of the battery 4 drops below a certain temperature, the control device 34 may again gradually increase the regenerative torque of the motor generator M.

[0053] 5, the control device 34 may be configured to finely adjust the regenerative torque of the motor generator M so that the heat generation temperature of the battery device 4 converges within a preset range equal to or less than the temperature threshold value HT. The control device 34 may also be configured to finely adjust the regenerative torque of the motor generator M so that the output voltage of the battery device 4 converges within a range equal to or less than the rated voltage.

[0054] The control device 34 is capable of performing regenerative control on the motor generator M until the battery 4 is fully charged while monitoring the output voltage of the battery 4 and the heat generation temperature of the battery 4. The charging status of the battery 4 (remaining power, time required to fully charge, etc.) may be displayed, for example, on a meter panel (not shown) provided in the driving unit 3, or may be displayed, for example, on a smartphone or tablet computer via wireless communication (including wireless internet communication).

[0055] [Another embodiment] The present invention is not limited to the configurations exemplified in the above-described embodiments, and other representative embodiments of the present invention will be exemplified below.

[0056] (1) In the above-described embodiment, the motor generator M drives and rotates both the traveling device (left and right front wheels 10 and left and right rear wheels 11) and the working device (grass cutting device 19), but this is not limited to this embodiment. The motor generator M may be configured to drive either the traveling device or the working device.

[0057] (2) In the above-described embodiment, the battery device 4 is exemplified as the power storage device, and a lithium ion battery is exemplified as the battery device 4, but the present invention is not limited to this embodiment. For example, the power storage device may be an all-solid-state battery.

[0058] (3) In the above embodiment, the output shaft 5A of the drive source 5 is connected to the rear PTO shaft 18. However, the output shaft 5A may be connected to the mid-PTO shaft 17. In this case, when the output shaft 5A of the drive source 5 is connected to the mid-PTO shaft 17 and the first clutch 17a is engaged, the motor generator M is rotated by the power of the drive source 5, and the motor generator M is able to generate electricity. The output shaft 5A of the drive source 5 may also be connected to the front PTO shaft 20. In this case, when the output shaft 5A of the drive source 5 is connected to the front PTO shaft 20 and the third clutch 20a is engaged, the motor generator M is rotated by the power of the drive source 5, and the motor generator M is able to generate electricity. In other words, the "power output shaft" of the present invention may be the mid-PTO shaft 17 or the front PTO shaft 20.

[0059] (4) In the embodiment described above with reference to Figure 5, the control device 34 sets the regenerative torque to zero when the second mode starts, but this is not limiting. The control device 34 may set the regenerative torque to a value greater than zero when the second mode starts.

[0060] (5) In the above-described embodiment, the "power output shaft" is a PTO shaft that can be connected to the input shaft of the working device, but the "power output shaft" may also be a traveling drive shaft. For example, when the electric work vehicle is towed by another vehicle, the traveling device is driven, and the driving force of the traveling device may be transmitted to the motor generator M via the power output shaft. Even in this configuration, the motor generator M can generate regenerative power.

[0061] (6) In the above-described embodiment, the mowing device 19 is exemplified as the working device. However, the working device is not limited to this embodiment, and may be, for example, a cultivator, a seeding device, a planter, a fertilizing device, a leaf cutting device, a spreading device, a baler, a mulcher, a stone picker, a rotary rake, a tedder, a towed harvesting and sorting device, a top pinching device, a tillage management device, a ridge forming device, etc.

[0062] (7) In the above embodiment, an electric tractor is shown as the electric work vehicle, but the electric work vehicle is not limited to this embodiment. For example, the electric work vehicle may be an electric rice transplanter, an electric spreader, an electric sprayer, an electric combine harvester, an electric mower, an electric cultivator, an electric wheel loader, an electric backhoe, etc.

[0063] The configurations disclosed in the above-described embodiments (including other embodiments, the same applies hereinafter) can be applied in combination with configurations disclosed in other embodiments, as long as no contradiction occurs. Furthermore, the embodiments disclosed in this specification are merely examples, and the present invention is not limited to these embodiments, and can be modified as appropriate within the scope of the purpose of the present invention. [Industrial Applicability]

[0064] The present invention can be used not only in electric tractors but also in various electric work vehicles such as combine harvesters, rice transplanters, and construction machines. [Explanation of symbols]

[0065] 5: Drive source 17: Mid PTO shaft (power output shaft, power transmission device) 17a: First clutch (power transmission device) 18: Rear PTO shaft (power output shaft, power transmission device) 18a: Second clutch (power transmission device) 19: Grass cutting equipment (work equipment) 34: Control device 36: Temperature detection unit 37: Voltage detection section VT: Voltage threshold (first threshold) HT: Temperature threshold (second threshold) M: Motor generator T1: Timing (preset time from the start of the second mode)

Claims

1. a power storage device that stores power; a motor generator electrically connected to the power storage device; a power transmission device having a power output shaft that transmits power from the motor generator to an outside; a control device that can switch between a first mode in which the motor generator is driven by electric power stored in the power storage device and a second mode in which, when the motor generator is rotated by power from an external drive source connected to the power output shaft, regenerative power is generated in the motor generator and the power storage device is charged with the regenerative power, The control device changes the regenerative torque of the motor generator so that it becomes larger as time passes from the start of the second mode until a predetermined time has elapsed, and maintains the changed regenerative torque setting after the predetermined time has elapsed.

2. The electric work vehicle according to claim 1 , wherein the control device sets the regenerative torque to zero when the second mode is started.

3. a voltage detection unit that detects an output voltage of the power storage device; 3. The electric work vehicle according to claim 1, wherein, in the second mode, when the output voltage of the power storage device exceeds a predetermined first threshold, the control device controls the motor generator so that the regenerative power is smaller than the regenerative power when the output voltage of the power storage device reaches the first threshold.

4. a temperature detection unit that detects a heat generation temperature of the power storage device, 3. The electric work vehicle according to claim 1, wherein, in the second mode, when the heat generation temperature exceeds a predetermined second threshold, the control device controls the motor generator so that the regenerative power is smaller than the regenerative power when the heat generation temperature reaches the second threshold.

5. 3. The electric work vehicle according to claim 1, wherein the power output shaft is a PTO shaft that can be connected to an input shaft of a work device.

6. A charging method for charging a power storage device mounted on an electric work vehicle, comprising: connecting an external drive source to a power output shaft of a power transmission device that transmits power from a motor generator electrically connected to the power storage device to an outside; a step of rotating the motor generator via the power transmission device using the drive source, causing the motor generator to generate regenerative power such that the regenerative power setting is changed to become larger as time passes from the start until a preset time has elapsed, and maintaining the changed regenerative power setting after the preset time has elapsed; charging the power storage device with the regenerated power.

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