Electric work vehicle

Abstract

To solve the problem in which: it has been demanded that a battery is charged in a state where work is successfully performed without troublesomeness, independently of difference in 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 KD; a control device 34 that controls a charging state by the power feeding device KD; and outside air temperature detection means G that detects an outside air temperature. When reservation charge is instructed in a state where the charging to the battery 4 is possible, the control device 34 executes reservation charge control of performing the charging to the battery 4 so that the charging is terminated at a time closer to a work start scheduled time as the outside air temperature detected by the outside air temperature detection means G is lower.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 the vehicle body, and a battery that supplies driving power to the electric motor. [Background technology]

[0002] In this type of electric work vehicle, when the battery power is consumed, it is charged from an external power supply device connected via a connector, as described in Patent Document 1, for example. Such battery charging must be done before work begins. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-22296 Summary of the Invention [Problem to be solved by the invention]

[0004] When charging the battery, for example, in winter when the outside temperature is low, the current that can be supplied during charging is low, so the charging process takes a long time. In contrast, in summer, the current that can be supplied during charging is high, but the battery temperature rises significantly as charging progresses, and by the time charging is complete, the battery temperature may be too high. As a result, if work is carried out immediately after charging, the battery temperature may exceed the allowable upper limit, which could cause battery malfunction. Thus, there is a risk that work cannot be carried out smoothly due to the difference in outside temperature at that time.

[0005] Therefore, there is a demand for a method for charging the battery in a state that allows for smooth and hassle-free operation regardless of the outside air temperature. [Means for solving the problem]

[0006] The characteristic configuration of the electric work vehicle according to the present invention is 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, and a connection part to which a power supply connector on the power supply device can be connected; a cover member that covers the battery; a control device that controls a charging state by the power supply device, and an outside air temperature detection means that detects an outside air temperature, and when a reserved charging command is issued while the battery is in a state where charging by the power supply device is possible, the control device is configured to execute reserved charging control to charge the battery so that the lower the outside air temperature detected by the outside air temperature detection means, the closer the charging will be to a scheduled work start time, The connection portion is provided inside the cover member, and the power supply device is connected to the connection portion when the cover member is open. It's at the point.

[0007] According to the present invention, the control device executes scheduled charging control prior to the scheduled start time of work. In scheduled charging control, the outdoor air temperature is detected by the outdoor air temperature detection means, and the lower the outdoor air temperature, the closer charging will end to the scheduled start time.

[0008] In other words, when the outside temperature is high, there will be a long waiting time until the scheduled start time of work, and even if the internal temperature of the battery rises as it is charged, it will decrease over time to a temperature suitable for work, and even if the temperature rises as a result of work, it is possible to avoid exceeding the allowable upper limit temperature.

[0009] On the other hand, when the outside temperature is low, the waiting time until the scheduled start time of work is shorter. When the outside temperature is low, even if the internal temperature of the battery rises during charging, the temperature does not rise significantly because the temperature at the start of charging is low, and it is possible to avoid exceeding the allowable upper limit temperature even if work is started immediately after charging.

[0010] Therefore, regardless of the difference in outside air temperature, it is possible to charge the battery in a state that allows work to be carried out smoothly without any hassle.

[0011] In the present invention, it is preferable that the outside air temperature detection means is provided with a temperature sensor that detects the temperature of the battery, and the control device is configured to determine the outside air temperature based on the detection result of the temperature sensor, and to adjust the charging current to the battery based on the detection result of the temperature sensor.

[0012] According to this configuration, since the temperature of the battery before charging is used to determine whether the outside air temperature at that time is high or low, it is easy to appropriately manage the state of charge of the battery during scheduled charging control in accordance with the actual temperature of the battery.

[0013] In the present invention, it is preferable that the outside air temperature detecting means is an outside air temperature sensor provided facing the outside of the vehicle body.

[0014] According to this configuration, the state of charge of the battery during scheduled charging control can be appropriately managed based on the outside air temperature outside the vehicle body, which affects changes in the temperature of the battery.

[0015] In the present invention, the outside air temperature detection means is provided with a timekeeping unit that has a calendar function and can determine the date, and when the timekeeping unit determines that it is winter, the control device preferably executes the scheduled charging control so that charging ends at a time closer to the scheduled start time of work than when it determines that it is summer.

[0016] According to this configuration, instead of directly detecting the temperature, the calendar function is used to execute scheduled charging control assuming that the outside air temperature is low in winter and high in summer. Therefore, the battery charging state can be appropriately managed in scheduled charging control with a simple configuration without using a temperature sensor or the like.

[0017] In the present invention, it is preferable that the control device, in the scheduled charging control, predicts the time required to complete charging based on the outside air temperature before charging of the battery is started and the charging characteristics of the battery, sets the waiting time from the scheduled charging completion time to the scheduled work start time to be shorter the lower the outside air temperature, and is configured to start charging of the battery at a time that is the total time prior to the scheduled work start time that is the sum of the required time and the waiting time.

[0018] When charging a battery, the maximum charging current that can be supplied varies depending on the temperature at the time, and the time required to complete charging also varies. The charging characteristics, which show the correlation between temperature and the time required for charging, are measured in advance and set as map data.

[0019] Therefore, in this configuration, the control device predicts the time required to complete charging based on the outside air temperature before the start of charging and the charging characteristics of the battery in the scheduled charging control. Standby without power consumption from the battery The standby time is set to be shorter as the outside air temperature drops. The charging start time is set so that charging is completed with the required standby time. In other words, charging of the battery starts at a time that is the total time including the required time and standby time, prior to the scheduled work start time.

[0020] By starting charging at the appropriate time in this way, the battery will be fully charged or nearly so by the scheduled start time of work, and work can be carried out smoothly without exceeding the allowable upper limit temperature. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 2 is a left side view of the 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 a configuration for charging. [Figure 5] 10 is a flowchart of a control operation. [Figure 6] FIG. 2 is a diagram showing the charging characteristics of a battery. [Figure 7] FIG. 4 is an explanatory diagram of the operation of reservation charge control. [Figure 8] FIG. 4 is an explanatory diagram of the operation of reservation charge control. [Figure 9] FIG. 10 is a block diagram showing a configuration for charging according to another embodiment. [Figure 10] FIG. 10 is a block diagram showing a configuration for charging according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0022] An embodiment of the present invention will be described with reference to the drawings. In the following description, unless otherwise specified, the direction of arrow F in the drawings will be 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 will be defined as "up," and the direction of arrow D as "down."

[0023] [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 Figure 1, the tractor has left and right front wheels 10, left and right rear wheels 11, and a cover member 12.

[0024] The tractor 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.

[0025] 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.

[0026] The driver's section 3 has a protective frame 30, a driver's seat 31, and a steering wheel 32. An operator can sit in the driver's seat 31. This allows the operator to get into the driver's 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 driver's section 3.

[0027] The tractor is equipped with a traveling battery 4. The cover member 12 is configured to be swingable about an opening / closing axis Q that extends 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 the closed state, the traveling battery 4 is covered by the cover member 12.

[0028] As shown in Fig. 2, the tractor is equipped with an inverter 14 and an electric motor M. The traction battery 4 supplies power to the inverter 14. The inverter 14 converts DC power from the traction 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.

[0029] 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.

[0030] The hydraulic pump 15a is driven by rotational power from the electric motor M. When the hydraulic pump 15a is driven, 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.

[0031] 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.

[0032] 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.

[0033] If a working 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 brush cutting device 19 is connected to the mid PTO shaft 17. The brush cutting device 19 is driven by the rotational power of the mid PTO shaft 17.

[0034] [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 commands to the inverter 14 in response to commands from the accelerator device 33. The inverter 14 is configured to adjust the power supplied from the traction battery 4 to the electric motor M to control the output of the electric motor M in response to commands from the control device 34.

[0035] [Configuration related to charging] As shown in FIG. 4, the driving 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.

[0036] A power feeding connector 36 on the power feeding device KD side is connected to the charging connection part 37. This charging connection part 37 complies with commonly used standards. With the power feeding connector 36 connected to the charging connection part 37, the traction battery 4 is charged via a power supply line 39. The traction battery 4 supplies high-voltage power (for example, several tens to several hundreds of volts) to the inverter 14 and the traction electric motor M via the power supply line 39.

[0037] The traction battery 4 is constructed using, for example, a lithium-ion battery, and although not shown, is made up of a large number of stacked, small, low-voltage unit cells, which are enclosed in a sealed storage case. Therefore, heat tends to build up inside the battery, and once the internal temperature rises, it is difficult to lower it. Therefore, the traction battery is equipped with a temperature sensor 40 that detects the internal temperature. The information detected by the temperature sensor 40 is input to the control device 34.

[0038] In addition to the traction battery 4, the tractor is equipped with an electrical equipment battery 41 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 traction battery 4 via a DC / DC converter 42. Temperature sensors 40 (40b, 40c, 40d) may also be provided in the electric motor M, the inverter 14, and the DC / DC converter 42. The operation panel 43 of the driver's 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 an inoperative state. The switching operation unit 44 is provided on the operation panel 43 below the steering wheel 32. The switching operation unit 44 includes an insertion portion 46 as an attachment portion into which a portable operation key 45 can be inserted and attached, and a push-button switch 47 that can be manually pressed. With the operation key 45 inserted and attached in the insertion portion 46, pressing the switch 47 switches the control device 34 from an inoperative state to an operable state.

[0039] 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.

[0040] The control device 34, inverter 14, driving battery 4 (including temperature sensor 40a), DC / DC converter 42, meter panel 48, charging connection unit 37, etc. are connected so as to be able to communicate data via a CAN (Controller Area Network) type signal harness 35. The control device 34 communicates with the charging connection unit 37 via a charging communication harness 49, and information such as whether the power feeding connector 36 is connected to the charging connection unit 37 and information about the charging current required on the work vehicle side is transmitted. Signals are also configured to be able to communicate between the charging connection unit 37 and the power feeding device KD. In addition, operation information of the switching operation unit 44 is input to the control device 34 .

[0041] [Charging control] When the power supply connector 36 is connected to the charging connection part 37 while the control device 34 is switched to the operable state, the control device 34 is placed in a state in which charging of the driving battery 4 by the power supply device KD is possible.

[0042] The control device 34 is configured to adjust the charging current based on the detection result of the temperature sensor 40 when charging the driving battery 4. That is, for the driving battery 4, the relationship between the state of charge (SOC) of the driving battery 4 and the maximum allowable value of the charging current is determined according to the temperature of the driving battery 4. Therefore, during charging, it is necessary to change and adjust the current value according to changes in the internal temperature and SOC so that the maximum allowable current value is not exceeded.

[0043] When a command for scheduled charging is issued while the power supply device KD is in a state where charging of the driving battery 4 is possible, the control device 34 is configured to execute scheduled charging control to charge the driving battery 4 so that the lower the outside air temperature detected based on the detection result of the temperature sensor 40, the closer the charging will end to the scheduled work start time. That is, in this embodiment, the temperature sensor 40 functions as outside air temperature detection means G.

[0044] A manually operable charging reservation switch 50 is provided on the operation panel 43 (see FIG. 4), and an operator can issue a command for reserved charging by operating the charging reservation switch 50.

[0045] Hereinafter, the reservation charge control by the control device 34 will be described with reference to the flowchart of FIG.

[0046] When the power supply connector 36 is connected to the charging connection section 37 and charging is possible while the power supply connector 36 is switched to an operable state, and when a command for scheduled charging is issued by operating the charging reservation switch 50 (step #01), the outside air temperature at that time is measured based on the detection result of the temperature sensor 40 (step #02).

[0047] Immediately after the vehicle has been driven to work in a field or the like, the internal temperature of the traction battery 4 has risen due to heating caused by the power supply, and so does not correspond to the outside air temperature. However, after the temperature that rose due to the power supply to the traction battery 4 has dropped over time, the temperature corresponds to the outside air temperature. Therefore, the outside air temperature can be estimated from the detection results of the temperature sensor 40.

[0048] Next, the time required to complete charging is predicted based on the outside air temperature and the charging characteristics of the driving battery 4 (step #03).

[0049] To explain further, various characteristics related to charging of the driving battery 4 have been measured and determined in advance, such as the correlation between the state of charge (SOC) and the maximum allowable value of the charging current, which changes depending on the temperature of the driving battery 4 as described above, and the correlation between the charging current and the temperature rise associated with charging.

[0050] Therefore, using these data, the correlation between the outside air temperature and the time required to fully charge the battery is calculated and stored as map data, as shown in Fig. 6, or the correlation can be calculated using an arithmetic expression, etc. Therefore, the time T1 (see Figs. 7 and 8) required until the scheduled charging completion time tk at which charging is completed can be predicted based on the outside air temperature.

[0051] Next, the waiting time T2 (see FIGS. 7 and 8) from the estimated charging completion time tk to the estimated work start time te is set to a shorter value as the outside air temperature decreases (step #04). For example, when the outside air temperature is low, such as in winter, the temperature of the drive battery 4 does not rise significantly even if the battery is fully charged. Therefore, even if the vehicle is immediately driven for work thereafter, there is no risk of the temperature rising to the upper limit of the allowable temperature. On the other hand, when the outside air temperature is high, such as in summer, the temperature of the drive battery 4 rises when the battery is fully charged. If the vehicle is immediately driven for work thereafter, there is a risk of the temperature of the drive battery 4 rising to the upper limit of the allowable temperature. Therefore, the waiting time T2 between the completion of charging and the start of work is set to a longer value as shown by line W1 in FIG. 7 if the outside air temperature is high, and set to a shorter value as shown by line W2 in FIG. 8 if the outside air temperature is low.

[0052] Then, the time that is obtained by subtracting the total time of the required time T1 and the waiting time T2 from the scheduled work start time te is set as the scheduled charging start time ts (step #05). Note that the scheduled work start time te is set in advance by the operator.

[0053] When the scheduled charging start time ts arrives, the necessary information is transmitted to the power supply device KD via the charging communication harness 49 to instruct the power supply device KD to supply power, and the power supply device KD starts charging the driving battery 4 (steps #06 and #07). The driving battery 4 is charged to a preset charging state, and when it is fully charged, charging stops (steps #08 and #09).

[0054] When the set waiting time T2 has elapsed since charging was stopped and the scheduled work start time te has arrived (step #10), the scheduled charging process ends and the operator performs driving operations. If the operator performs operations to start work before the waiting time T2 has elapsed and the scheduled work start time ts has arrived, the meter panel may display a message that the temperature of the driving battery 4 may rise. Although the temperature sensor 40a of the driving battery 4 has been used as an example in the description above, the temperature sensor 40b of the electric motor M, the temperature sensor 40c of the inverter 14, and the temperature sensor 40d of the DC / DC converter 42 may also be used as the temperature sensor 40, which is the outside air temperature detection means G. When these temperature sensors 40 are used, the accuracy is slightly lower than when measurement is performed using the temperature sensor 40a of the driving battery 4, but this is often not a problem in practice, and so these can also be used.

[0055] [Another embodiment] (1) As the outside air temperature detection means G, instead of the temperature sensor 40 that detects the internal temperature of the driving battery 4, an outside air temperature sensor 51 may be provided facing the outside of the vehicle body as shown in Figure 9, and scheduled charging control may be performed based on the detection information of the outside air temperature sensor 51.

[0056] (2) Instead of the temperature sensor 40 that detects the internal temperature of the driving battery 4, the outside air temperature detection means G may be configured to include a clock unit 52 that has a calendar function and can determine the current date, as shown in Figure 10. When the clock unit 52 determines that it is winter, the control device 34 may be configured to execute scheduled charging control so that charging ends closer to the scheduled work start time than when it determines that it is summer.

[0057] In other words, instead of measuring the outside air temperature or the battery temperature, etc., the calendar function may be used to set the standby time T2 to a short value in winter when the outside air temperature is low, to a long value in summer when the outside air temperature is high, and to an intermediate length in spring or autumn when the outside air temperature is intermediate.

[0058] (3) In the scheduled charging control, instead of setting the required time T1 and waiting time T2 as described above, the total time including the required time and waiting time may be measured in advance through an experiment or the like in response to changes in the outside air temperature, and the correlation between the outside air temperature and the total time may be stored as map data, or the total time may be calculated from the outside air temperature.

[0059] (4) In the above embodiment, the driving battery 4 is configured so that the outside is covered in a sealed storage case. However, instead of this configuration, a battery with an open outside may be used.

[0060] (5) In each of the above embodiments, the present invention is not limited to electric tractors, but can also be applied to electric agricultural vehicles such as electric combine harvesters and electric rice transplanters, and electric work vehicles that perform various types of work. [Industrial Applicability]

[0061] The present invention can be applied to electric work vehicles that perform various types of work, such as agricultural work. [Explanation of symbols]

[0062] 4 Battery 12 Cover member 34 Control device 40 Temperature Sensor 51 Outside air temperature sensor 52 Timing section G. Outside air temperature detection means M Electric motor T1 Travel time T2 waiting time te Scheduled start time of work tk Estimated charging completion time

Claims

1. an electric motor capable of driving the vehicle body; a battery that supplies driving power to the electric motor and is chargeable by an external power supply device; a connection portion to which a power supply connector of the power supply device can be connected; a cover member that covers the battery; a control device that controls a charging state by the power supply device; an outside air temperature detection means for detecting an outside air temperature, the control device is configured to, when a command for scheduled charging is issued in a state in which the battery can be charged by the power supply device, execute scheduled charging control to charge the battery so that the lower the outside air temperature detected by the outside air temperature detection means, the closer the charging will be to a scheduled work start time, The connection portion is provided inside the cover member, and the power supply device is connected to the electric work vehicle when the cover member is open.

2. The outside air temperature detection means is provided with a temperature sensor that detects the temperature of the battery, 2. The electric work vehicle according to claim 1, wherein the control device is configured to determine the outside air temperature based on the detection result of the temperature sensor, and to adjust the charging current to the battery based on the detection result of the temperature sensor.

3. 2. The electric work vehicle according to claim 1, wherein the outside air temperature detecting means is an outside air temperature sensor provided facing the outside of the vehicle body.

4. The outside air temperature detection means is provided with a timekeeping unit that has a calendar function and can determine the current date, 2. The electric work vehicle according to claim 1, wherein, when the timing unit determines that it is winter, the control device executes the scheduled charging control so that charging ends at a time closer to the scheduled work start time than when the timing unit determines that it is summer.

5. The control device 5. The electric work vehicle according to claim 1, wherein the scheduled charging control predicts the time required to complete charging based on the outside air temperature before charging of the battery is started and the charging characteristics of the battery, and sets a standby time during which no power is consumed from the battery between the scheduled charging completion time and the scheduled work start time so that the lower the outside air temperature, the shorter the standby time, and starts charging of the battery at a time that is the total time prior to the scheduled work start time that is the sum of the required time and the standby time.

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