Electric work vehicle

Abstract

To solve the problem in which: it has been demanded that a battery can be efficiently charged even at a low outside air temperature.SOLUTION: An electric work vehicle comprises: an electric motor M that can drive a vehicle body to make the vehicle body travel; a battery 4 that supplies a driving power to the electric motor M and that can be charged by an external power feeding device; a connection part 37 that can be connected with a power feeding connector 36 at the power feeding device side; a control device 34 that controls a charging state by the power feeding device KD; and temperature detection means 40 that detects a temperature of the battery 4. The control device 34 is configured to execute temperature raising control of heating the battery 4 until the temperature of the battery 4 rises to a target temperature prior to the charging to the battery 4 if the temperature of the battery 4 detected by the temperature detection means 40 is equal to or less than a setting temperature.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to an electric work vehicle including an electric motor capable of driving a vehicle body and a battery that supplies driving power to the electric motor.

Background Art

[0002] In this type of electric work vehicle, for example, as described in Patent Document 1, when the power of the battery is consumed, charging is performed from an external power supply device connected via a connection connector. And when charging is performed, when an external power supply device is connected and a charging start is commanded, charging is configured to be performed immediately.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As the battery, for example, a large-capacity lithium-ion battery or the like is used. Such a battery is easily affected by temperature, and has a characteristic that the lower the temperature, the smaller the maximum charging current that can flow through the battery during charging.

[0005] By the way, when the electric work vehicle is used in a cold region, when starting the charging operation for the battery, the outside air temperature may be as low as, for example, 10 degrees Celsius or lower. In such a low-temperature environment, the maximum charging current that can flow through the battery is suppressed to a smaller current value compared to the case of normal temperature.

[0006] Conventionally, when charging is performed when the outside air temperature is low, when an external power supply device is connected and charging start is commanded, the charging operation is immediately performed, so the charging current decreases and a long time is required for charging.

[0007] Therefore, there has been a demand to enable efficient charging of the battery even when the outside air temperature is low.

Means for Solving the Problem

[0008] The characteristic configuration of the electric work vehicle according to the present invention includes an electric motor capable of driving the vehicle body, a battery that supplies driving power to the electric motor and can be charged by an external power supply device, a connection portion to which a power supply connector on the power supply device side can be connected, a control device that controls the charging state by the power supply device, and temperature detection means for detecting the temperature of the battery. An inverter that converts DC power from the battery into AC power and supplies it to the electric motor, a radiator that cools the refrigerant flowing through a cooling path provided in the electric motor and the inverter, and a blower fan that blows air to the radiator. is provided, and when the temperature of the battery detected by the temperature detection means is equal to or lower than a set temperature, the control device performs temperature increase control to warm the battery until the battery rises to a target temperature prior to charging the battery. As an option, the blower fan is operated to ventilate the cooling air that has passed through the radiator toward the battery. lies in this point.

[0009] According to the present invention, when charging the battery when the temperature of the battery is equal to or lower than the set temperature, the control device executes temperature increase control to warm the battery until the battery rises to the target temperature prior to charging.

[0010] After the temperature of the battery rises to or above the target temperature by executing the temperature increase control, the charging state by the power supply device is controlled to charge the battery. By increasing the temperature of the battery in this way, the maximum charging current that can flow through the battery becomes larger than when in a low temperature state.

[0011] Therefore, even when the outside air temperature is low, a large charging current can be passed immediately after starting charging, so the time required to charge up to full charge is shortened, and charging of the battery can be performed efficiently. When the electric work vehicle performs work, DC power from the battery is converted into AC power by the inverter and supplied to the electric motor, and the electric motor is driven. At this time, heat is generated due to the flow of current in the electric motor and the inverter. Therefore, the blower fan blows air to the radiator through which the refrigerant flows through the cooling path provided in the electric motor and the inverter, reducing the temperature of the electric motor and the inverter. When charging the battery at intervals after the above-described work is performed when the outside air temperature is low, the temperature of the battery may decrease due to the influence of the outside air temperature. Therefore, according to this configuration, the battery is heated and its temperature is raised by using the heat of the refrigerant remaining heated in the radiator. Therefore, it is possible to raise the temperature of the battery by effectively using the heat generated in the inverter and the electric motor during work.

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Brief Description of the Drawings

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Figure 1

Figure 2

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Figure 4

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Figure 6

Embodiments for Carrying Out the Invention

[0024] 〔Reference Embodiment〕 For the form for carrying out the present invention, Reference it will be described with reference to the drawings. In the following description, unless otherwise specified, the direction of arrow F in the drawings is defined as "front", the direction of arrow B as "rear", the direction of arrow L as "left", and the direction of arrow R as "right". The direction of arrow U in the drawings is defined as "up", and the direction of arrow D as "down".

[0025] 〔Overall configuration of the tractor〕 Hereinafter, a tractor as an example of the electric work vehicle according to the present invention will be described. As shown in FIG. 1, the tractor includes left and right front wheels 10 and left and right rear wheels 11 as vehicle body traveling devices, and a cover member 12.

[0026] The tractor includes a body frame 2 and an operation unit 3. The body frame 2 is supported by the left and right front wheels 10 and the left and right rear wheels 11.

[0027] The cover member 12 is disposed at the front of the body. And the operation unit 3 is provided behind the cover member 12. In other words, the cover member 12 is disposed in front of the operation unit 3.

[0028] The operation unit 3 has a protection frame 30, an operation seat 31, and a steering wheel 32. The operator can sit on the operation seat 31. Thereby, the operator can board the operation unit 3. By operating the steering wheel 32, the left and right front wheels 10 are steered. The operator can perform various driving operations in the operation unit 3.

[0029] The tractor includes a traveling battery 4. The cover member 12 is configured to be swingable around an opening and closing axis Q along the left - right direction of the body. Thereby, the cover member 12 is configured to be openable and closable. When the cover member 12 is in the closed state, the traveling battery 4 is covered by the cover member 12.

[0030] As shown in FIG. 2, the tractor includes an inverter 14 and an electric motor M. The traveling battery 4 supplies power to the inverter 14. The inverter 14 converts the DC power from the traveling battery 4 into AC power and supplies it to the electric motor M. Then, the electric motor M is driven by the AC power supplied from the inverter 14.

[0031] As shown in FIGS. 2 and 3, the tractor includes 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.

[0032] The hydraulic pump 15a is driven by the rotational power from the electric motor M. When the hydraulic pump 15a is driven, rotational power is output from the hydraulic motor 15b. Note that the hydrostatic continuously variable transmission 15 is configured such that the rotational power is transmitted between the hydraulic pump 15a and the hydraulic motor 15b and is continuously variable. The hydrostatic continuously variable transmission 15 is configured to be able to change the transmission ratio steplessly.

[0033] The rotational power output from the hydraulic motor 15b is transmitted to the transmission 16. The rotational power transmitted to the transmission 16 is shifted by the gear-type transmission mechanism of the transmission 16 and distributed to the left and right front wheels 10 and the left and right rear wheels 11. Thereby, the left and right front wheels 10 and the left and right rear wheels 11 are driven.

[0034] As shown in FIGS. 2 and 3, the tractor includes a mid PTO shaft 17 and a rear PTO shaft 18 as power take-off shafts. The 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. Thereby, the mid PTO shaft 17 and the rear PTO shaft 18 rotate.

[0035] If a working device as an external device is connected to the mid PTO shaft 17 or the rear PTO shaft 18, the working device will be 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 mowing device 19 is connected to the mid PTO shaft 17. The mowing device 19 is driven by the rotational power of the mid PTO shaft 17.

[0036] 〔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 an inverter 14. The accelerator device 33 is provided near the steering wheel 32. The accelerator device 33 includes a lever that can be swung (not shown) and a potentiometer that is operated by the swinging 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 command the inverter 14 in response to the command of the accelerator device 33. The inverter 14 is configured to adjust the power supplied from the traveling battery 4 to the electric motor M in response to the command of the control device 34 and control the output of the electric motor M.

[0037] 〔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 portion 37 to which a power supply connector 36 of the power supply device KD can be connected. The charging connection portion 37 is provided inside the cover member 12 and is exposed outward 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.

[0038] The charging connection part 37 conforms to a standard specification that is generally used. When the power supply connector 36 is connected to the charging connection part 37, charging of the traveling battery 4 is performed via the power supply line 39. The traveling battery 4 supplies power at a high voltage (for example, several tens of volts to several hundreds of volts) to the inverter 14 and the traveling electric motor M via the power supply line 39.

[0039] The traveling battery 4 is configured using, for example, a lithium-ion battery. Although not shown in the figure, it is configured in a state where a large number of small low-voltage unit batteries (cells) are stacked, and the outside is covered and stored in a sealed state by a storage case. Therefore, heat is likely to accumulate inside the battery, and when the internal temperature rises, it is difficult for the temperature to drop. Thus, the traveling battery 4 is provided with a temperature sensor 40 as temperature detection means for detecting the internal temperature. The detection information of the temperature sensor 40 is input to the control device 34.

[0040] In addition to the traveling battery 4, the tractor is provided with an electrical component battery 41 that supplies power to the control device 34 and other electrical components. The electrical component battery 41 supplies power at a low voltage (12 volts) to drive the electrical components. The electrical component battery 41 is charged with the power supplied from the traveling battery 4 via the DC / DC converter 42.

[0041] The operation unit 3 is provided with a switching operation unit 44 as start command means capable of switching the control device 34 between an operable state and a non-operable state. The switching operation unit 44 includes a plug-in part 46 as a mounted part into which the portable operation key 45 can be inserted and mounted, and a push-button type switch 47 that can be manually pushed. When the switch 47 is pushed in a state where the operation key 45 is inserted and mounted in the plug-in part 46, the control device 34 can be switched from the non-operable state to the operable state. The operation key 45 functions as a key that can be identified only on this work vehicle, similar to a general vehicle key.

[0042] The operation panel 43 is provided with, for example, a meter panel 48 that displays the running state of the vehicle body, the working state, battery information (charge amount, temperature, etc.). The meter panel 48 is connected to the control device 34 and its operation is controlled by the control device 34.

[0043] The control device 34, the inverter 14, the traveling battery 4 (including the temperature sensor 40), the DC / DC converter 42, the meter panel 48, and the charging connection part 37, etc. are communicably connected via a signal harness 35 of the CAN (Controller Area Network) system. The control device 34 communicates with the charging connection part 37 via the charging communication harness 49, and information about whether the power supply connector 36 is connected to the charging connection part 37 and information about the charging current required on the work vehicle side, etc. are transmitted. A signal is also configured to be communicable between the charging connection part 37 and the power supply device KD. Also, the operation information of the switching operation part 44 is input to the control device 34.

[0044] 〔Control for Charging〕 When the control device 34 is switched to the operable state with the power supply connector 36 connected to the charging connection part 37, it switches to the charging mode. And in the charging mode, it is configured to charge the traveling battery 4 by the power supply device KD.

[0045] And if the temperature of the traveling battery 4 detected by the temperature sensor 40 is equal to or lower than the set temperature Ts, the control device 34 is configured to execute temperature rise control to warm the traveling battery 4 until the traveling battery 4 rises to the target temperature Tm prior to charging the traveling battery 4.

[0046] Hereinafter, the specific charging control of the control device 34 will be described with reference to the flowchart of FIG. 5.

[0047] When charging the traveling battery 4, an operator connects the power supply connector 36 of the power supply device KD to the charging connection part 37. Next, in the switching operation part 44 provided in the operation part 3, the operation key 45 is inserted and mounted in the insertion part 46, and the switch 47 is pressed. When the control device 34 determines this, it switches to the charging mode (steps #01, #02, #03).

[0048] When the charging mode is entered, it is determined whether the internal temperature Tx of the traveling battery 4 detected by the temperature sensor 40 is equal to or lower than the set temperature Ts (step #04). At this time, if the internal temperature Tx of the traveling battery 4 is higher than the set temperature Ts, the charging operation is immediately started (step #08). If the temperature Tx of the traveling battery 4 is equal to or lower than the set temperature Ts, before charging the traveling battery 4, the electric motor M is rotationally driven to warm the traveling battery 4 (step #05).

[0049] That is, by supplying a driving current to the electric motor M, a current flows through the internal resistance of the traveling battery 4, generating Joule heat and raising the temperature of the traveling battery 4. The set temperature Ts is set to a temperature at which the available current value becomes extremely small if it drops any further, for example, a very low temperature below freezing. The process of step #05 corresponds to the temperature increase control.

[0050] As described above, the power of the electric motor M is configured to be transmitted to the hydrostatic continuously variable transmission 15, the mid PTO shaft 17, and the rear PTO shaft 18. When the electric motor M is rotationally driven in step #05, the hydrostatic continuously variable transmission 15 is rotationally driven by the power of the electric motor M, and the mid PTO shaft 17 and the rear PTO shaft 18 are rotationally driven by the power of the electric motor M.

[0051] The operation of supplying drive current to the electric motor M to warm up the traveling battery 4 continues until the temperature of the traveling battery 4 rises above the target temperature Tm (step #06). When the temperature of the traveling battery 4 rises above the target temperature Tm, the operation of the electric motor M is stopped (step #07), and charging of the traveling battery 4 from the power supply device KD is started (step #08).

[0052] As the target temperature Tm, any temperature at which the available current value can perform charging efficiently may be used. That is, it may be set to the same temperature as the set temperature Ts, or it may be a temperature lower than the set temperature Ts, or it may be a temperature higher than the set temperature Ts.

[0053] After starting the charging operation, when the traveling battery 4 is fully charged, the charging operation is stopped (steps #09, #10).

[0054]

[0055] 〔Embodiment〕 The above reference In the embodiment, as the temperature rising control, a configuration is adopted in which the electric motor M is rotationally driven. However, instead of this configuration, or in addition to this configuration, the following configuration may be adopted.

[0056] That is, a radiator 50 that cools the refrigerant flowing through the cooling path provided in the electric motor M and the inverter 14, and a blower fan 51 that blows air to the radiator 50 may be provided, and the control device 34 may be configured to operate the blower fan 51 as the temperature rising control and ventilate the cooling air that has passed through the radiator 50 toward the traveling battery 4.

[0057] This work vehicle is equipped with a cooling mechanism for cooling an electric motor M, an inverter 14, a DC / DC converter 42, etc. As shown in FIG. 6, the cooling mechanism includes a radiator 50, an electric pump 52, and a refrigerant circulation path 53. In the electric motor M, the inverter 14, and the DC / DC converter 42, cooling paths are formed in the casing, and they are connected by pipes to form the refrigerant circulation path 53. The electric pump 52 circulates the refrigerant, and the refrigerant that has absorbed heat is cooled by the cooling action of the blower fan 51 in the radiator 50. The wind generated by the blower fan 51 also acts on the oil cooler 54. The oil cooler 54 cools the hydraulic oil of a hydrostatic continuously variable transmission 15 or the like.

[0058] The radiator 50 and the oil cooler 54 are provided in front of the traveling battery 4, and the wind generated by the blower fan 51 is configured to flow toward the traveling battery 4 after passing through the radiator 50 and the oil cooler 54.

[0059] When the outside air temperature is low, in order to prevent the temperature of the traveling battery 4 from dropping after work is performed, by operating the blower fan 51, the cooling air (warm air heated by the refrigerant) that has passed through the radiator 50 is ventilated toward the traveling battery 4, and the heat of the refrigerant can be used to raise the temperature of the traveling battery 4.

[0060] 〔Alternative Embodiment〕 (1) In the above embodiment, in the temperature rise control, the hydrostatic continuously variable transmission 15 is rotationally driven by the power of the electric motor M, and the power is transmitted to the mid PTO shaft 17 and the rear PTO shaft 18. However, instead of this configuration, the hydrostatic continuously variable transmission 15 may be rotationally driven by the power of the electric motor M, and the power may not be transmitted to the mid PTO shaft 17 and the rear PTO shaft 18. Also, the mid PTO shaft 17 and the rear PTO shaft 18 may be rotationally driven, and the power may not be transmitted to the hydrostatic continuously variable transmission 15. Further, the electric motor M may be rotationally driven, and the power may not be transmitted to each of the hydrostatic continuously variable transmission 15, the mid PTO shaft 17, and the rear PTO shaft 18. ( 2 )In the above embodiment, as the temperature raising control, a configuration is adopted in which the electric motor M is rotationally driven. Instead of this configuration, or in addition to this configuration, a dedicated heating means (such as a heater) capable of warming the traveling battery 4 may be provided near the traveling battery 4, and as the temperature raising control, a configuration may be adopted in which the heating means is operated.

[0061] ( 3In the above embodiment, the control device 34 is configured to switch to the charging mode when it is switched to the operable state while the power supply connector 36 is connected to the charging connection portion 37. Instead of this configuration, after the control device 34 is switched to the operable state in advance, when the power supply connector 36 is connected to the charging connection portion 37, it may be configured to switch to the charging mode.

[0062] ( 4 )In the above embodiment, the traveling battery 4 is configured such that the outside is covered in a sealed state by the storage case. Instead of such a configuration, a battery of an open type may be used.

Industrial Applicability

[0063] The present invention can be applied not only to tractors but also to various electric work vehicles such as rice transplanters, combines, and construction machines.

Explanation of Signs

[0064] 4 Battery 14 Inverter 34 Control Device 37 Connection Port 40 Temperature sensor (temperature detection means) 50 Radiator 51 Blower Fan M Electric Motor

Claims

【Claim 1】 An electric motor capable of driving the vehicle body; A battery that supplies driving power to the electric motor and can be charged by an external power supply device; A connection part to which a power supply connector on the power supply device side can be connected; A control device that controls the charging state by the power supply device; Temperature detection means for detecting the temperature of the battery; An inverter that converts DC power from the battery into AC power and supplies it to the electric motor; A radiator that cools the refrigerant flowing through a cooling path provided in the electric motor and the inverter; A blower fan that blows air to the radiator, and is provided; The control device, if the temperature of the battery detected by the temperature detection means is equal to or lower than a set temperature, prior to charging the battery, as a temperature increase control for warming the battery until the battery rises to a target temperature, operates the blower fan to direct the cooling air that has passed through the radiator toward the battery. An electric work vehicle.

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