Power-operated work vehicle

Abstract

To solve the problem in which: it has been demanded that a battery can be charged to such a state as to drive an electric motor even if a concerned work vehicle remains unused for a long period of time.SOLUTION: An electric work vehicle comprises: an electric motor M that can drive a vehicle body to make the vehicle body travel; a first battery 4 that supplies a driving power to the electric motor M and that can be charged by an external power feeding device KD; a second battery 41 that supplies a power to electric and electronic parts mounted on the vehicle body and that can be charged; a voltage converter 42 that can supply a power while adjusting a voltage value between the first battery 4 and the second battery 41; and a control device 43 supplied with the power from the second battery 41 and that controls a charging state by the power feeding device KD while controlling actuation of the voltage converter 42. The control device 43 repeatedly executes an interval charging process of controlling the actuation of the voltage converter 42 so as to charge the second battery 41 with the power from the first battery 4, every setting period.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an electric work vehicle equipped with an electric motor capable of driving a vehicle body to travel, and a battery that supplies driving power to the electric motor. [Background technology]

[0002] This type of electric work vehicle is equipped with a low-voltage on-board battery (second battery) that supplies power to electronic devices such as a control device that executes various controls, in addition to a battery (first battery) that supplies power to an electric motor for vehicle body travel, as described in Patent Document 1, for example. The control device executes control of the operation of the electric motor and charging of the battery, etc. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-99086 Summary of the Invention [Problem to be solved by the invention]

[0004] The first battery is configured to have a large capacity to drive the electric motor, but the second battery has a smaller capacity than the first battery. If the work vehicle is not used for a long period of time, the second battery may discharge and the charge level may drop significantly. If the charge level of the second battery drops in this way, there is a risk that the control device may not be able to operate. If this happens, the first battery cannot be charged, and the vehicle cannot run by driving the electric motor.

[0005] Therefore, there has been a demand for a system that allows the battery to be charged to a state where the electric motor can be driven even if the work vehicle is not used for an extended period of time. [Means for solving the problem]

[0006] The electric work vehicle according to the present invention is characterized by comprising an electric motor capable of driving a vehicle body, a first battery which supplies driving power to the electric motor and is chargeable by an external power supply device, a second battery which supplies power to electrical equipment mounted on the vehicle body and is chargeable, a voltage converter which is capable of supplying power while adjusting the voltage value between the first battery and the second battery, and a control device which receives power from the second battery, controls the charging state by the power supply device, and controls the operation of the voltage converter, and the control device comprises: Fixed The present invention is characterized in that an interval charging process is executed, which controls the operation of the voltage converter so as to charge the second battery with electric power from the first battery, repeatedly at set intervals.

[0007] According to the present invention, the control device executes the interval charging process every time a set period elapses. That is, the second battery is charged with power from the first battery. For example, even if the work vehicle goes from being in use to being unused, the control device can prevent the charge level of the second battery from decreasing by repeatedly executing the interval charging process every set period thereafter.

[0008] As a result, even if the vehicle is left unused for a long period of time, it is possible to prevent the charge level of the second battery from decreasing significantly, and it is possible to operate the control device and charge the first battery using an external power supply device.

[0009] Therefore, even if the work vehicle is not used for a long period of time, it is possible to charge the first battery to a state where the electric motor can be driven.

[0010] In the present invention, it is preferable that the set cycle is set to a length that allows a sufficient charge amount to be secured even if charging is not performed within the cycle.

[0011] According to this configuration, when the interval charging process is performed, the charge amount of the second battery is secured, and the charge amount does not decrease to a level where the control device cannot be operated due to discharging.

[0012] In the present invention, the control device is configured to control the operation of the electric motor, and is provided with a start command means for switching the control device to an operable state by manually operating it when a portable operation key is close to the vehicle body or when the operation key is attached to the attachment part, and the control device is configured to switch to a non-operating state in which it does not control the operation of the electric motor when the operation key is switched to a state where it is away from the vehicle body or a state where the operation key is removed from the attachment part, and it is preferable that the control device is configured to be able to execute the interval charging process even in the non-operating state.

[0013] According to this configuration, when the start command means is manually operated with the operation key close to the vehicle body or with the operation key attached to the attachment portion, the control device switches to an operable state, and work, etc. is performed by the work vehicle. Then, after the work is completed, when the operator moves away from the vehicle body while still holding the operation key, or when the operation key switches to a state where it is removed from the attachment portion, the control device switches to a non-operated state in which it does not control the operation of the electric motor.

[0014] After the control device is switched to the inoperative state, the work is completed and the operator leaves the vehicle body, so it is conceivable that the work vehicle will be left unused for a long period of time. However, because the control device can execute the interval charging process even after switching to the inoperative state in this way, it is possible to prevent the second battery from discharging and the charge level from decreasing.

[0015] In the present invention, it is preferable that the control device is configured to operate in a power saving mode in which only the interval charging process can be executed after the operation key is switched to a state in which it is separated from the vehicle body or a state in which the operation key is removed from the mounting portion.

[0016] According to this configuration, even if the work vehicle is left unused for a long period of time, the control device operates in a power saving mode, thereby reducing power consumption of the second battery and preventing the second battery from losing its charge level prematurely.

[0017] In the present invention, it is preferable that a spare battery capable of supplying power to the control device is provided in addition to the second battery.

[0018] According to this configuration, even if the charge level of the second battery decreases for some reason, the control device can be operated by the spare battery to execute the interval charging process. [Brief description of the drawings]

[0019] [Figure 1] FIG. [Diagram 2] FIG. 4 is a left side view showing the arrangement of an inverter and the like. [Diagram 3] FIG. [Figure 4] FIG. 2 is a block diagram showing a configuration for charging. [Diagram 5] 4 is a flowchart of a control operation. [Figure 6] FIG. 11 is a block diagram showing a configuration for charging according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The 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 drawing is "forward", the direction of the arrow B is "backward", the direction of the arrow L is "left", and the direction of the arrow R is "right". The direction of the arrow U in the drawing is "upward", and the direction of the arrow D is "downward".

[0021] [Overall configuration of the tractor] The following describes a tractor as an example of an electric work vehicle according to the present invention. As shown in Fig. 1, the tractor has left and right front wheels 10, left and right rear wheels 11, and a cover member 12.

[0022] The tractor includes a machine body frame 2 and a driving section 3. The machine body 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. 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 driving section 3 has a protective frame 30, a driving seat 31, and a steering wheel 32. An operator can sit in the driving seat 31. This allows the operator to get into the driving section 3. The left and right front wheels 10 are steered by operating the steering wheel 32. The operator can perform various driving operations in the driving section 3.

[0025] The tractor is equipped with a traveling battery 4 as a first battery. The cover member 12 is configured to be swingable about an opening / closing axis Q that runs along 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 traveling battery 4 is covered by the cover member 12.

[0026] As shown in Fig. 2, the tractor is equipped with an inverter 14 and an electric motor M. The traveling battery 4 supplies power to the inverter 14. The inverter 14 converts DC power from the traveling battery 4 into AC power and supplies it to the electric motor M. The electric motor M is then driven by the AC power supplied from the inverter 14.

[0027] 2 and 3, the tractor is equipped with a hydrostatic continuously variable transmission 15 and a transmission 16. As shown in Fig. 3, the hydrostatic continuously variable transmission 15 has a hydraulic pump 15a and a hydraulic motor 15b.

[0028] The hydraulic pump 15a is driven by rotational power from the electric motor 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 configured so that the gear ratio can be changed steplessly.

[0029] The rotational power output from the hydraulic motor 15b 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.

[0030] 2 and 3, the tractor is equipped with a mid PTO shaft 17 and a rear PTO shaft 18. Rotational power output from the electric motor M is distributed to the hydraulic pump 15a, the mid PTO shaft 17, and the rear PTO shaft 18. This causes the mid PTO shaft 17 and the rear PTO shaft 18 to rotate.

[0031] If a working device is connected to the mid PTO shaft 17 or the rear PTO shaft 18, the working device is driven by the rotational power of the mid PTO shaft 17 or the rear PTO shaft 18. For example, as shown in Fig. 2, in this embodiment, a grass cutting device 19 is connected to the mid PTO shaft 17. The grass cutting device 19 is driven by the rotational power of the mid PTO shaft 17.

[0032] [Configuration related to motor control] As shown in FIG. 4, the configuration related to the control of the electric motor M includes an accelerator device 33, a control device 34 that controls the operation of the electric motor M, and the inverter 14. The accelerator device 33 is provided near the steering wheel 32. Although not shown, the accelerator device 33 includes a lever that can be swung and a potentiometer that is operated by swung operation of the lever. The accelerator device 33 is connected to the control device 34. The control device 34 is connected to the inverter 14 via a signal harness 35. The control device 34 is configured to issue a command to the inverter 14 in response to a command from the accelerator device 33. The inverter 14 is configured to adjust the power supplied from the driving battery 4 to the electric motor M in response to a command from the control device 34 to control the output of the electric motor M.

[0033] [Configuration related to charging] As shown in Fig. 4, the traveling battery 4 can be charged by an external power supply device KD. The tractor is provided with a charging connection part 37 to which a power supply connector 36 of the power supply device KD can be connected. The charging connection part 37 is provided inside the cover member 12, and is exposed to the outside when the cover member 12 is swung open. The control device 34 controls the operation of the electric motor M and also controls the charging state by the power supply device KD.

[0034] The charging connection part 37 complies with commonly used standards. With the power supply connector 36 connected to the charging connection part 37, charging of the driving battery 4 is performed via a power supply line 39. The driving battery 4 supplies high voltage power (for example, several tens to several hundreds of volts) to the inverter 14 and the electric motor M via the power supply line 39.

[0035] The driving battery 4 is, for example, a lithium ion battery, and although not shown, is made up of a number of small, low-voltage unit batteries (cells) stacked on top of each other, and is stored in a storage case that is covered on the outside in a sealed state.

[0036] In addition to the traveling battery 4, the tractor is equipped with an electrical equipment battery 41 as a second battery that supplies power to the control device 34 and other electrical equipment. The electrical equipment battery 41 supplies low-voltage (12 volt) power to drive the electrical equipment. The electrical equipment battery 41 is charged with power supplied from the traveling battery 4 via a DC / DC converter (voltage converter) 42. The DC / DC converter 42 is capable of supplying power while adjusting the voltage value between the traveling battery 4 and the electrical equipment battery 41. In other words, the electrical equipment battery 41 can be charged by supplying power.

[0037] The driving unit 3 is provided with a switching operation unit 44 as a start command means capable of switching the control device 34 between an operable state and a non-operated state. The switching operation unit 44 is provided with an insertion section 46 as an attachment section into which a portable operation key 45 can be inserted and attached, and a push-button type switch 47 that can be manually pressed. With the operation key 45 inserted and attached in the insertion section 46, the control device 34 can be switched from a non-operated state to an operable state by pressing the switch 47. The operation key 45 functions as a key that can be identified only for the work vehicle, similar to a key for a general vehicle.

[0038] The operation panel 43 is provided with a meter panel 48 that displays, for example, the vehicle's running state, working state, battery information (charge level and temperature), etc. The meter panel 48 is connected to the control device 34, and its operation is controlled by the control device 34.

[0039] The control device 34, inverter 14, driving battery 4, DC / DC converter 42, meter panel 48, charging connection unit 37, etc. are connected to each other so as to be able to communicate data via a signal harness 35 of the CAN (Controller Area Network) type. The control device 34 communicates with the charging connection unit 37 via a charging communication harness 49, and information as to whether the power supply connector 36 is connected to the charging connection unit 37 and information on the charging current required on the work vehicle side are transmitted. Signals are also configured to be able to communicate between the charging connection unit 37 and the power supply device KD. Operation information of a switching operation unit 44 is also input to the control device 34.

[0040] When the power supply connector 36 is connected to the charging connection portion 37 and the operation key 45 is inserted into the insertion portion 46, the control device 34 switches to the charging mode, and the driving battery 4 can be charged by the power supply device KD.

[0041] When the switch 47 is pressed while the operation key 45 is inserted into the insertion portion 46, the control device 34 switches to an operable state in which the electric motor M can be operated. When the operation key 45 is switched to a state in which it is removed from the insertion portion 46, the control device 34 is configured to switch to a non-operated state in which the operation control of the electric motor M is not performed.

[0042] The control device 34 is configured to execute an interval charging process that controls the operation of the DC / DC converter 42 so as to charge the electrical equipment battery 41 with power from the driving battery 4, repeatedly at set intervals even when the control device 34 is not in operation.

[0043] The control of the control device 34 will be described below with reference to the flow chart of FIG. When working with the work vehicle, the operator inserts the operation key 45 into the insertion portion 46 of the switching operation unit 44 provided on the operation panel 43 of the driver's unit 3. If the power supply connector 36 of the power supply device KD is connected to the charging connection portion 37 at that time, charging processing for the traveling battery is executed (steps #1, #2, #3).

[0044] In the charging process, the necessary information is sent via the charging communication harness 49 to the power supply device KD to supply power, and the power supply device KD starts charging the running battery 4. The running battery 4 is then charged up to a preset charging state, and charging stops when the battery is fully charged.

[0045] When the switch 47 is pressed while the power supply connector 36 is not connected to the charging connection portion 37, the electric motor M is switched to an operable state (step #04). Then, although not described in detail, the operation of the electric motor M is controlled based on an operation command from the operator (step #05). In this operation control of the electric motor M, when the switch 47 is pressed again, the operation of the electric motor M can be stopped.

[0046] After the work using the work vehicle is completed, the operator removes the operation key 45 from the insertion portion 46. When the operation key 45 is removed, the control device 34 switches to a non-operating state in which the operation of the electric motor M is not controlled (steps #06, #07). When switched to the non-operating state, the control device 34 switches to a power saving mode in which only the interval charging process described below can be executed. The power saving mode is a state in which less power is consumed than the normal power mode in which the electric motor M is operated to perform work.

[0047] When the vehicle is switched to the inoperative state, an interval charging process is executed to control the operation of the DC / DC converter 42 so that the electric component battery 41 is charged with power from the driving battery 4 repeatedly at set intervals.

[0048] That is, when the state is switched to the non-operating state, the timer starts counting (step #08), and when the timer count time reaches a set time (corresponding to a set cycle), the operation of the DC / DC converter 42 is controlled to charge the electrical equipment battery 41 with power from the driving battery 4 (steps #10, #11). When the charging process ends, the timer count value is reset (step #12), and the timer starts counting again. Then, the processing of steps #08 to #12 is repeated every set time. The processing of steps #08, #10, #11, and #12 corresponds to the interval charging processing.

[0049] If the operation key 45 is inserted and attached into the insertion portion 46 while the interval charging process is being performed, the process returns to the initial state (step #01) (step #09). At that time, the mode returns from the power saving mode to the normal power mode. After that, the charging process for the driving battery 4 or the operation control of the electric motor M can be performed.

[0050] The set time (set cycle) is set to a length that allows a sufficient charge to be secured even if charging is not performed within that cycle. For example, it can be set to a length of about one week. In other words, it is set to a length that prevents the electrical equipment battery 41 from discharging and causing the charge to become very low.

[0051] By carrying out this type of interval charging process, even if the work vehicle is not used for an extended period of time, it is possible to prevent the charge level of the electrical equipment battery 41 from becoming extremely low, and the driving battery 4 can be charged smoothly.

[0052] [Another embodiment] (1) In the above embodiment, the control device 34 is configured to perform interval charging processing and control the operation of the electric motor M. However, instead of this configuration, a first control device that performs charging processing for the driving battery 4 and the electrical equipment battery 41, and a second control device that controls the operation of the electric motor M may be provided separately, and the first control device may be configured to perform the interval charging processing.

[0053] (2) In the above embodiment, the operation key 45 is configured to be inserted into the insertion portion 46 for attachment. However, instead of this configuration, the operation key 45 may be configured to be capable of wireless communication with a receiving portion on the vehicle body, and when the switch 47 is operated while the operation key 45 is close to the vehicle body, the control device 34 may be switched to an operable state.

[0054] (3) In the above embodiment, the control device 34 is configured to switch to the power saving mode after the operation key 45 is switched to the state where it is removed from the insertion portion 46. However, instead of this configuration, the control device 34 may be configured to remain in the normal power mode even after the operation key 45 is switched to the state where it is removed from the insertion portion 46.

[0055] (4) In the above embodiment, only the electrical equipment battery 41 is provided as a battery for supplying power to the control device 34. However, instead of this configuration, as shown in FIG. 6, a configuration may be used in which, in addition to the electrical equipment battery 41, a spare battery 50 is provided which can be used in cases where the electrical equipment battery 41 is not operational for some reason. [Industrial Applicability]

[0056] The present invention can be applied not only to tractors but also to various electric work vehicles such as rice transplanters, combine harvesters, and construction machines. [Explanation of symbols]

[0057] 4. Running battery (first battery) 34 Control device 41 Battery for electrical equipment (second battery) 42 DC / DC converter (voltage converter) 43 Control device 44 Switch (start command means) 45 Operation keys 46 Insertion part (attached part) KD Power Supply Equipment M Electric motor

Claims

1. An electric motor capable of driving the vehicle body; a first battery that supplies driving power to the electric motor and is chargeable by an external power supply device; A second battery that supplies power to electrical equipment mounted on the vehicle body and is rechargeable; a voltage converter capable of supplying electric power while adjusting a voltage value between the first battery and the second battery; a control device that receives power from the second battery, controls a charging state by the power supply device, and controls an operation of the voltage converter; The control device of the electric work vehicle executes an interval charging process that controls the operation of the voltage converter so as to repeatedly charge the second battery with power from the first battery at fixed set intervals.

2. 2. The electric work vehicle according to claim 1, wherein the set cycle is set to a length that allows a sufficient charge amount to be secured even if charging is not performed within the cycle.

3. The control device is configured to control operation of the electric motor; a start command means for switching the control device to an operable state by manually operating a portable operation key in a state where the operation key is close to the vehicle body or in a state where the operation key is attached to a mounting portion; the control device is configured to switch to a non-operating state in which it does not control the operation of the electric motor when the operation key is switched to a state in which the operation key is separated from the vehicle body or a state in which the operation key is switched to a state in which the operation key is removed from the mounting portion, 3. The electric work vehicle according to claim 1, wherein the control device is configured to be able to execute the interval charging process even in the non-operating state.

4. 4. The electric work vehicle according to claim 3, wherein the control device is configured to operate in a power saving mode in which only the interval charging process can be executed after the operation key is switched to a state in which it is separated from the vehicle body or a state in which the operation key is removed from the mounting portion.

5. 5. The electric work vehicle according to claim 1, further comprising a spare battery capable of supplying power to the control device, in addition to the second battery.

Images