Electric Tractor

Abstract

To protect a battery from overload while satisfactorily maintaining workability.SOLUTION: An electric tractor 1 comprises a hydraulic pump 7, a motor 42 for the pump, a motor 43 for a PTO, a first battery 21, and an electric controller 61. The hydraulic pump 7 supplies a hydraulic system with hydraulic oil. The motor 42 for the pump is an electric motor that drives the hydraulic pump 7. The motor 43 for a PTO is an electric motor that drives a PTO shaft 8. The first battery 21 is used in common by the motor 42 for the pump and the motor 43 for a PTO, and supplies the motors with electric power. The electrically-driven controller 61 controls distribution of the electric power to the motor 42 for the pump and the motor 43 for the PTO. The electric controller 61, when an overload state of the first battery 21 is detected, reduces electric power to be supplied to the motor 43 for the PTO, in preference to reducing electric power to be supplied to the motor 42 for the pump.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electric tractor in which electric power is distributed and supplied to a plurality of electric motors from a common battery. [Background technology]

[0002] Patent Document 1 discloses an electric tractor. The tractor includes an electric motor for traveling, an electric motor for work, and a battery. The electric motor for traveling drives wheels. The electric motor for work drives a rotary tilling device. The battery supplies power to each motor. The rotation speed of the electric motor for work is detected by a work rotation speed detection sensor. The tractor includes an operation control unit that functions as a traveling speed control means and a work power control means. When the operation control unit detects that the detected value of the rotation speed of the electric motor for work has fallen below a set value, it controls the rotation speed of the traveling motor to decrease accordingly. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-150560 A Summary of the Invention [Problem to be solved by the invention]

[0004] When the total power consumption of the motors exceeds the power supply of the battery, the burden on the battery increases, causing it to deteriorate. In this regard, Patent Document 1 does not disclose the relationship between the control of multiple electric motors to reduce the burden on the battery.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to protect a battery from overload while maintaining good operability.

[0006] The problem to be solved by the present invention has been described above. Next, the means for solving this problem and the effects thereof will be described.

[0007] According to a first aspect of the present invention, there is provided an electric tractor having the following configuration. That is, the electric tractor includes a hydraulic pump, a pump motor, a PTO motor, a battery, and a control unit. The hydraulic pump supplies hydraulic oil to a hydraulic device provided in a traveling vehicle body. The pump motor is an electric motor that drives the hydraulic pump. The PTO motor is an electric motor that drives a PTO shaft provided in the traveling vehicle body. The battery is common to the pump motor and the PTO motor, and supplies power to these motors. The control unit controls the distribution of power to the pump motor and the PTO motor. When an overload state of the battery is detected, the control unit reduces the power supplied to the PTO motor in priority to reducing the power supplied to the pump motor.

[0008] This makes it possible to prevent the operation of the hydraulic equipment from becoming unstable while also preventing overloading of the battery.

[0009] According to a second aspect of the present invention, there is provided an electric tractor having the following configuration. That is, the electric tractor includes a hydraulic pump, a pump motor, a traveling motor, a battery, and a control unit. The hydraulic pump supplies hydraulic oil to a hydraulic device included in a traveling body. The pump motor is an electric motor that drives the hydraulic pump. The traveling motor is an electric motor that is driven to travel the traveling body. The battery is common to the pump motor and the traveling motor, and supplies power to these motors. The control unit controls the distribution of power to the pump motor and the traveling motor. When an overload state of the battery is detected, the control unit reduces the power supplied to the traveling motor in priority to reducing the power supplied to the pump motor.

[0010] This makes it possible to prevent the operation of hydraulic equipment from becoming unstable and to prevent battery overload. Also, the speed of the traveling machine is reduced, making it possible to notify the operator of battery overload at an early stage.

[0011] According to a third aspect of the present invention, there is provided an electric tractor having the following configuration. That is, the electric tractor includes a PTO motor, a traveling motor, a battery, and a control unit. The PTO motor is an electric motor that drives a PTO shaft equipped on a traveling body. The traveling motor is an electric motor that is driven to travel the traveling body. The battery is common to the PTO motor and the traveling motor, and supplies power to these motors. The control unit controls the distribution of power to the PTO motor and the traveling motor. When an overload state of the battery is detected, the control unit reduces the power supplied to the traveling motor in priority to reducing the power supplied to the PTO motor.

[0012] This allows priority to be given to decelerating the vehicle, which can be expected to reduce the load to a certain extent, thereby quickly and reliably eliminating battery overload.

[0013] According to a fourth aspect of the present invention, there is provided an electric tractor having the following configuration. That is, the electric tractor includes a PTO motor, a traveling motor, a battery, and a control unit. The PTO motor is an electric motor that drives a PTO shaft equipped on a traveling body. The traveling motor is an electric motor that is driven to travel the traveling body. The battery is common to the PTO motor and the traveling motor, and supplies power to these motors. The control unit controls the PTO motor and the traveling motor. When an overload state of the battery is detected, the control unit reduces the rotation speed of the traveling motor, and reduces the rotation speed of the PTO motor in conjunction with this.

[0014] As a result, even if the traveling speed is reduced due to detection of an overload, disturbance of the working pitch can be suppressed.

[0015] According to a fifth aspect of the present invention, there is provided an electric tractor having the following configuration. That is, the electric tractor includes a hydraulic pump, a pump motor, a PTO motor, a traveling motor, a battery, and a control unit. The hydraulic pump supplies hydraulic oil to a hydraulic device provided in a traveling vehicle body. The pump motor is an electric motor that drives the hydraulic pump. The PTO motor is an electric motor that drives a PTO shaft provided in the traveling vehicle body. The traveling motor is an electric motor that is driven to travel the traveling vehicle body. The battery is common to the pump motor, the PTO motor, and the traveling motor, and supplies power to these motors. The control unit controls the distribution of power to the pump motor, the PTO motor, and the traveling motor. When an overload state of the battery is detected, the control unit reduces the power supplied to the traveling motor with the highest priority among the pump motor, the PTO motor, and the traveling motor. If an overload state of the battery is detected even after the power supplied to the traction motor has been reduced, the control unit reduces the power supplied to the PTO motor in priority over reducing the power supplied to the pump motor.

[0016] This makes it possible to prevent battery overload while ensuring stable operation of hydraulic equipment. By prioritizing driving deceleration, where a load reduction can be expected to a certain degree with certainty, over PTO deceleration, battery overload can be quickly and reliably eliminated. [Brief description of the drawings]

[0017] [Figure 1] 1 is a block diagram showing the overall configuration of an electric tractor according to an embodiment of the present invention; [Diagram 2] 6 is a graph illustrating the control of the present embodiment when an overload occurs in the first battery. [Diagram 3]4 is a flowchart illustrating a process performed in an electric drive controller. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Next, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a block diagram showing the overall configuration of an electric tractor 1 according to an embodiment of the present invention. Fig. 2 is a graph explaining the control of this embodiment when an overload occurs in the first battery 21. Fig. 3 is a flowchart explaining the processing performed in the electric drive controller 61.

[0019] The electric tractor 1 shown in Fig. 1 is configured as an agricultural tractor. The electric tractor 1 includes a traveling machine body 2 as a vehicle body portion capable of traveling in a farm field.

[0020] A working machine 3 can be connected to the traveling machine body 2. Examples of the working machine 3 include a cultivator (manufacturing machine), a plow, a fertilizer applicator, a grass cutter, a seed sowing machine, etc. Various types of working machines 3 can be attached to the traveling machine body 2 as needed.

[0021] The front part of the traveling body 2 is supported by a pair of left and right front wheels 4, and the rear part of the traveling body 2 is supported by a pair of left and right rear wheels 5.

[0022] A transmission device 6 is disposed at the rear of the traveling body 2. A speed change mechanism, for example, made up of a gear train, is disposed inside the transmission device 6. The transmission device 6 changes the speed of power input from a traveling motor 41, which will be described later. The power changed in speed by the transmission device 6 is transmitted to the front wheels 4 and the rear wheels 5.

[0023] A traveling motor 41, a pump motor 42, and a PTO motor 43 are arranged at appropriate positions on the electric tractor 1.

[0024] The traction motor 41 generates a driving force for rotating the rear wheels 5 and the front wheels 4. An output shaft of the traction motor 41 is connected to an input shaft of the transmission device 6.

[0025] The pump motor 42 drives the hydraulic pump 7. The hydraulic pump 7 is a device for supplying hydraulic oil to various hydraulic devices, and is disposed at an appropriate position of the traveling machine body 2.

[0026] The hydraulic device to which the hydraulic pump 7 supplies hydraulic oil may be any hydraulic device, for example, a lift actuator (not shown). The lift actuator is provided at the rear of the traveling body 2 in order to adjust the height and attitude of the work machine 3 mounted on the traveling body 2. Additionally, the hydraulic pump 7 may be used to supply hydraulic oil to, for example, a hydraulic steering device (not shown).

[0027] The PTO motor 43 drives the PTO shaft 8. The PTO shaft 8 can be connected to an input shaft of the work machine 3 in a state in which the work machine 3 is connected to the traveling machine body 2. The PTO motor 43 can drive the work machine 3 via the PTO shaft 8.

[0028] The traveling motor 41, the pump motor 42, and the PTO motor 43 are all configured as electric motors. These motors can be configured as, for example, permanent magnet synchronous motors (PM motors), but are not limited to this.

[0029] The traveling machine body 2 includes a first battery (battery) 21, a second battery 22, a BMS unit 26, a DC / DC converter 27, a traveling inverter 46, a pump inverter 47, and a PTO inverter 48.

[0030] The first battery 21 is a high voltage battery and supplies power to the travel motor 41, the pump motor 42, and the PTO motor 43.

[0031] The traveling machine body 2 is provided with a BMS unit (battery management device) 26. BMS is an abbreviation for battery management system. The BMS unit 26 is configured as a computer and has a function of monitoring the voltage, temperature, etc. of the first battery 21 and detecting abnormalities. The BMS unit 26 is electrically connected to an electric drive controller 61 described later.

[0032] The second battery 22 is a battery for the accessories, and its output voltage is lower than that of the first battery 21. The second battery 22 supplies power to the accessories 28. Various types of accessories 28 are conceivable, and examples of such accessories include an electric motor for a cooling fan and an electric motor for a pump that circulates cooling water.

[0033] The DC / DC converter 27 converts the high voltage of the first battery 21 to a lower voltage for charging the second battery 22.

[0034] The first battery 21 and the second battery 22 may have any configuration, and may be, for example, a lithium ion secondary battery.

[0035] The traveling inverter 46, the pump inverter 47, and the PTO inverter 48 are electrically connected to the corresponding three electric motors, respectively. All three inverters are electrically connected to a common first battery 21. These inverters boost the voltage of the first battery 21 and supply it to the traveling motor 41, the pump motor 42, and the PTO motor 43.

[0036] The traveling machine body 2 includes an electric drive controller (control unit) 61. The traveling inverter 46, the pump inverter 47, and the PTO inverter 48 are each electrically connected to the electric drive controller 61.

[0037] The electric drive controller 61 is configured as a known computer and includes a CPU, a ROM, a RAM, etc. The electric drive controller 61 controls the operation of each of the three transmission motors via the three inverters. The electric drive controller 61 controls the rotation speed of each of the electric motors, and in general, the rotation speed of the electric motor is closely related to the power consumption. Therefore, it can be said that the electric drive controller 61 essentially controls the distribution of power from the first battery 21 to the travel motor 41, the pump motor 42, and the PTO motor 43 via the three inverters.

[0038] The electric drive controller 61 further monitors the temperature and load of each part, and automatically limits the operation of each electric motor as necessary.

[0039] The electric tractor 1 includes a plurality of operation members 51 and a plurality of operation sensors 52.

[0040] The operation members 51 are members such as levers, pedals, dials, switches, and touch panels that can be operated by an operator. In this embodiment, known members are used as the operation members 51, so they will be described briefly. As an example, the operation members 51 include a steering handle, a travel speed change lever, a reverse lever, a travel mode switch, a PTO speed change lever, a draft lever, and a work equipment lift lever.

[0041] The steering handle is an operating member for changing the turning angle of the front wheels 4. The travel speed change lever is an operating member for changing the travel speed of the electric tractor 1. The reverse lever is an operating member for switching the electric tractor 1 between forward and reverse. The travel mode switch is an operating member for switching, for example, between two-wheel drive using only the rear wheels 5 and four-wheel drive using the rear wheels 5 and the front wheels 4. The PTO speed change lever is an operating member for changing the rotation speed of the PTO shaft 8. The draft lever is an operating member for indicating the traction force when performing draft control that maintains a predetermined traction force by automatically changing the height of the work implement 3 according to the traction load. The work implement lift lever is an operating member for changing the height of the work implement 3.

[0042] The operation sensor 52 is configured as, for example, a potentiometer, a switch, an optical sensor, a touch panel sensor, etc. The operation sensor 52 can detect an operation performed by an operator on the operation member 51. The operation sensor 52 is electrically connected to a tractor-side controller 62, which will be described later.

[0043] The traveling machine body 2 includes a tractor-side controller 62. The tractor-side controller 62 is configured as a known computer, and includes a CPU, a ROM, a RAM, and the like.

[0044] The tractor-side controller 62 and the electric drive controller 61 are electrically connected to each other and can transmit and receive control signals. In this embodiment, the control signal is transmitted and received by the CAN communication, but the communication may be performed by another method.

[0045] Examples of signals transmitted from the tractor-side controller 62 to the electric drive controller 61 include a travel speed command value for the traveling machine body 2, a rotation speed command value for the PTO shaft 8, and torque command values ​​for the traveling motor 41 and the PTO motor 43. In addition to these, for example, the above-mentioned travel mode, the operating position of the reverse lever, the control gain, the release level of the hydraulic valve, etc. can be transmitted from the tractor-side controller 62 to the electric drive controller 61.

[0046] Examples of signals transmitted from the electric drive controller 61 to the tractor-side controller 62 include the actual values ​​of the rotation speed and torque of the travel motor 41, the pump motor 42, and the PTO motor 43. In addition, the electric drive controller 61 can transmit to the tractor-side controller 62, for example, the charge rate of the first battery 21, the margin up to the output allowable value of the first battery 21, the motor slip rate, etc.

[0047] The electric tractor 1 further includes a meter device 53 and a hydraulic controller 54.

[0048] The meter device 53 can display the state of the electric tractor 1, such as the vehicle speed, etc., so that the operator can visually confirm it. The meter device 53 is electrically connected to the tractor-side controller 62.

[0049] The hydraulic controller 54 can control, for example, the operation of the lifting actuator described above via an electromagnetic valve (not shown).

[0050] Next, the control performed by the electric drive controller 61 will be described with reference to Fig. 2. Note that the graph in Fig. 2 is shown conceptually for the purpose of explanation, and each electric motor is not necessarily controlled strictly as shown in the graph.

[0051] Consider a case where an electric tractor 1 with a working machine 3 (e.g., a tiller) attached to a traveling body 2 performs work while traveling. Electricity from the first battery 21 is supplied to the traveling motor 41, the pump motor 42, and the PTO motor 43, and the three motors are driven simultaneously.

[0052] Normally, as shown in graph (a) of FIG. 2, the total power supplied from the first battery 21 to the three motors does not exceed the output allowable value of the first battery 21.

[0053] For example, when the electric tractor 1 approaches a hard field, the tilling resistance increases, which increases the load on the PTO motor 43 that drives the implement 3. As a result, consider a case where the overall output exceeds the output allowable value of the first battery 21, as shown in FIG.

[0054] Here, in order to reduce the load on the first battery 21, the electric drive controller 61 can also issue deceleration commands to all of the travel motor 41, the pump motor 42, and the PTO motor 43. This configuration also makes it possible to reduce the power supplied to the first battery 21. However, if the hydraulic pressure of the pump motor 42 decreases, the operation of various hydraulic devices becomes unstable.

[0055] Therefore, the electric drive controller 61 of this embodiment is configured to slow down the driving motor 41 or the PTO motor 43 in priority to the speed of the pump motor 42 when the supply power of the first battery 21 exceeds a predetermined threshold value.

[0056] Specifically, when an overload is detected as shown in Fig. 2(b), the electric drive controller 61 immediately controls only the driving motor 41 to appropriately decelerate, thereby reducing the power consumption of the driving motor 41 as shown in Fig. 2(c), and as a result, the overall output is also reduced.

[0057] 2(c), where only the traveling motor 41 is decelerated, the relationship between the rotation speed of the traveling motor 41 and the rotation speed of the PTO motor 43, which was maintained in (a) and (b), changes. Since it is undesirable for the grain size of the tilled soil to be unstable, the electric drive controller 61 of this embodiment, after achieving the state of FIG. 2(c), immediately controls the PTO motor 43 to decelerate to a speed that corresponds to the traveling speed after deceleration.

[0058] 2(d), the outputs of the traveling motor 41 and the PTO motor 43 are rebalanced. As a result, the load on the first battery 21 is not excessively large, and stable work quality can be obtained.

[0059] 2(a) to 2(d), the output of the pump motor 42 is maintained constant, thereby enabling the hydraulic equipment to operate stably and reliably.

[0060] In this manner, in this embodiment, when the outputs of the traveling motor 41, the pump motor 42, and the PTO motor 43 are an overload for the first battery 21, the traveling motor 41 is decelerated first. Therefore, the operator driving the electric tractor 1 can be informed of the overload of work in an easy-to-understand manner by the deceleration of the traveling speed. Also, in this embodiment, only the traveling vehicle speed decreases first, but this is only transient, and the PTO motor 43 immediately decelerates to follow the traveling vehicle speed. In this manner, the vehicle speed and the PTO speed are controlled in a coordinated manner, eliminating the need for the operator to make fine adjustments.

[0061] The above describes the case where the load on the PTO motor 43 increases and the first battery 21 becomes overloaded, but essentially the same control is performed when the load on the pump motor 42 increases and the first battery 21 becomes overloaded.

[0062] Next, the control performed by the electric drive controller 61 will be described with reference to the flowchart of FIG.

[0063] When the processing of Figure 3 is started, the electric drive controller 61 controls the driving inverter 46, the pump inverter 47, and the PTO inverter 48 so as to drive the driving motor 41, the pump motor 42, and the PTO motor 43 at speeds based on commands received from the tractor side controller 62 (step S101).

[0064] Next, the electric drive controller 61 detects the outputs of the travel motor 41, the pump motor 42, and the PTO motor 43, and calculates a total value. The output of each motor can be obtained by detecting the current value flowing through each motor using a current sensor, or by providing a torque sensor on the output shaft or the like.

[0065] The electric drive controller 61 determines whether the total output value of the three motors exceeds a predetermined value (step S102). If the total output value does not exceed the predetermined value, the process returns to step S101.

[0066] If it is determined in step S102 that the total output of the three motors exceeds the predetermined value, the electric drive controller 61 controls the travel inverter 46 to decelerate the travel motor 41 while monitoring the total output (step S103). The deceleration of the travel motor 41 continues until the total output of the three motors falls below the predetermined value. That is, the travel motor 41 decelerates by an amount equivalent to the difference between the total output of the three motors and the predetermined value.

[0067] When the deceleration of the traveling motor 41 is completed, the electric drive controller 61 controls the PTO inverter 48 to reduce the speed of the PTO motor 43 (step S104). The deceleration of the PTO motor 43 is performed in proportion to the amount by which the speed of the traveling motor 41 is decelerated by the control of step S103. This makes it possible to quickly restore the disturbance of the working pitch (in other words, the tilling pitch) of the electric tractor 1.

[0068] The rotation speed of the traveling motor 41 can be obtained, for example, simply based on a command from the electric drive controller 61 to the traveling motor 41. Also, for example, a rotation sensor can be provided on one of the transmission shafts (not shown) that constitute the transmission device 6, and the rotation speed of the traveling motor 41 can be obtained based on detection by this rotation sensor. By obtaining the rotation speed of the traveling motor 41 before and after step S103, it is possible to obtain how much the traveling motor 41 has decelerated in step S103.

[0069] With respect to the pump motor 42, the electric drive controller 61 controls the pump inverter 47 to maintain the same speed as in step S101 (step S105).

[0070] Next, the electric drive controller 61 attempts to gradually restore the speeds of the traveling motor 41 and the PTO motor 43 that were once reduced (step S106). That is, it is considered that the total value of the outputs of the three motors will be lower than the predetermined value of step S102 with a certain margin by the processes of steps S103 and S104. Also, if the large load detected in step S102 subsides in a short time, the reduction in the load also becomes a margin. The electric drive controller 61 increases the speeds of the traveling motor 41 and the PTO motor 43 while monitoring the total value of the outputs of the three motors in a manner that eliminates the margin. The amount by which the speeds of the traveling motor 41 and the PTO motor 43 increase per unit time is appropriately determined so that the balance of the rotation speeds of both motors is maintained. The process of step S106 is performed until the total value of the outputs of the three motors reaches the predetermined value of step S102 or the speeds of the traveling motor 41 and the PTO motor 43 reach the original command values.

[0071] The electric drive controller 61 waits while repeating the process of step S106 until a predetermined time has elapsed (step S107). This predetermined time is set to an appropriate length in consideration of preventing hunting of the traveling speed.

[0072] Thereafter, the electric drive controller 61 determines whether the travel motor 41, the pump motor 42, and the PTO motor 43 can operate with the original command value described in step S101 (step S108). This determination can be made by checking whether the current speeds of the travel motor 41 and the PTO motor 43 have already reached the original command value, and whether the current total value of the outputs of the three motors is sufficiently lower than the predetermined value in step S102.

[0073] If it is determined in step S108 that each motor can operate with the original command value, the process returns to step S101. If it is determined that each motor cannot operate with the original command value, an error is generated and notified to the operator (step S109).

[0074] As described above, the electric tractor 1 of this embodiment includes the hydraulic pump 7, the pump motor 42, the PTO motor 43, the first battery 21, and the electric drive controller 61. The hydraulic pump 7 supplies hydraulic oil to the hydraulic device of the traveling body 2. The pump motor 42 is an electric motor that drives the hydraulic pump 7. The PTO motor 43 is an electric motor that drives the PTO shaft 8 of the traveling body 2. The first battery 21 is common to the pump motor 42 and the PTO motor 43, and supplies power to these motors. The electric drive controller 61 controls the distribution of power to the pump motor 42 and the PTO motor 43. When an overload state of the first battery 21 is detected, the electric drive controller 61 reduces the power supplied to the PTO motor 43 in priority to reducing the power supplied to the pump motor 42.

[0075] This makes it possible to prevent the operation of the hydraulic equipment from becoming unstable, while also preventing overload of the first battery 21.

[0076] The electric tractor 1 of this embodiment also includes a traveling motor 41. The traveling motor 41 is an electric motor that is driven to make the traveling body 2 travel. The first battery 21 is common to the pump motor 42 and the traveling motor 41, and supplies power to these motors. The electric drive controller 61 controls the distribution of power to the pump motor 42 and the traveling motor 41. When an overload state of the first battery 21 is detected, the electric drive controller 61 reduces the power supplied to the traveling motor 41 in priority over reducing the power supplied to the pump motor 42.

[0077] This makes it possible to prevent the operation of the hydraulic equipment from becoming unstable while preventing overload of the first battery 21. In addition, the speed of the traveling machine body 2 is reduced, so that the operator can be informed of the overload of the first battery 21 at an early stage.

[0078] In the electric tractor 1 of this embodiment, when an overload state of the first battery 21 is detected, the electric drive controller 61 reduces the power supplied to the traction motor 41 in priority over reducing the power supplied to the PTO motor 43.

[0079] As a result, by giving priority to deceleration of traveling, which can be expected to reduce the load with some certainty, overload on the first battery 21 can be quickly and reliably eliminated.

[0080] In the electric tractor 1 of this embodiment, when an overload state of the first battery 21 is detected, the electric drive controller 61 reduces the rotational speed of the traveling motor 41 and, in conjunction with this, reduces the rotational speed of the PTO motor 43.

[0081] As a result, even if the traveling speed is reduced due to detection of an overload, disturbance of the working pitch can be suppressed.

[0082] In the electric tractor 1 of this embodiment, when an overload state of the first battery 21 is detected, the electric drive controller 61 reduces the power supplied to the traveling motor 41 with the highest priority among the pump motor 42, the PTO motor 43, and the traveling motor 41. If an overload state of the first battery 21 is still detected after reducing the power supplied to the traveling motor 41, the electric drive controller 61 reduces the power supplied to the PTO motor 43 with priority over reducing the power supplied to the pump motor 42.

[0083] This ensures stable operation of the hydraulic equipment while preventing overload on the first battery 21. By prioritizing travel deceleration, which can be expected to reduce the load to a certain extent, over PTO deceleration, overload on the first battery 21 can be quickly and reliably eliminated.

[0084] Although the preferred embodiment of the present invention has been described above, the above configuration can be modified, for example, as follows.

[0085] In the above embodiment, the priority order of power supply is as follows: first, pump motor 42, second, PTO motor 43, and third, travel motor 41. However, for example, the second, travel motor 41, and third, PTO motor 43 may be given priority.

[0086] The deceleration of the PTO motor 43 shown in step S104 of FIG. 3 may be performed simultaneously with the deceleration of the travel motor 41 in step S103.

[0087] The speed adjustment of the PTO motor 43 in step S104 may not be performed automatically, but may be performed manually by an operator.

[0088] The processing in FIG. 3 may be performed on the tractor-side controller 62 side instead of the electric drive controller 61 side.

[0089] When an overload of the first battery 21 is detected and the rotation speed of the traveling motor 41 is set to zero in step S103, if the total output of each motor exceeds a predetermined value and the overload state exists, it is preferable to immediately reduce the rotation speed of the PTO motor 43. For example, when there are large stones in the soil in a mountainous field, the load on the PTO motor 43 from the PTO motor 43 may be considerably large even when the traveling body 2 is stopped. Furthermore, if the rotation speed of the PTO motor 43 is set to zero but the total output of each motor exceeds a predetermined value and the overload state exists, the rotation speed of the pump motor 42 may be controlled to be reduced. [Explanation of symbols]

[0090] 1 Electric Tractor 2 Running body 7 Hydraulic Pump 8 PTO shaft 21 First Battery (Battery) 41 Driving motor 42 Pump motor 43 PTO motor 61 Electric drive controller (control unit)

Claims

1. A hydraulic pump that supplies hydraulic oil to a hydraulic device provided on the traveling machine body; a pump motor which is an electric motor that drives the hydraulic pump; A PTO motor which is an electric motor that drives a PTO shaft provided on the traveling machine body; a common battery for supplying power to the pump motor and the PTO motor; a control unit that controls distribution of power to the pump motor and the PTO motor; Equipped with the control unit, when an overload state of the battery is detected, reduces the power supplied to the PTO motor in priority over reducing the power supplied to the pump motor.

2. A hydraulic pump that supplies hydraulic oil to a hydraulic device provided on the traveling machine body; a pump motor which is an electric motor that drives the hydraulic pump; A traveling motor which is an electric motor that drives the traveling machine body to travel; a common battery for supplying power to the pump motor and the traveling motor; a control unit that controls distribution of electric power to the pump motor and the traveling motor; Equipped with an electric tractor, wherein when an overload state of the battery is detected, the control unit reduces the power supplied to the traction motor in priority to reducing the power supplied to the pump motor.

3. A PTO motor which is an electric motor that drives a PTO shaft provided on the traveling machine body; A traveling motor which is an electric motor that drives the traveling machine body to travel; a common battery for supplying power to the PTO motor and the traction motor; a control unit that controls distribution of electric power to the PTO motor and the traction motor; Equipped with the control unit, when an overload state of the battery is detected, reduces the power supplied to the traction motor in priority over reducing the power supplied to the PTO motor.

4. A PTO motor which is an electric motor that drives a PTO shaft provided on the traveling machine body; A traveling motor which is an electric motor that drives the traveling machine body to travel; a common battery for supplying power to the PTO motor and the traction motor; a control unit for controlling the PTO motor and the driving motor; Equipped with The control unit reduces the rotation speed of the driving motor when an overload state of the battery is detected, and reduces the rotation speed of the PTO motor in conjunction with the reduction in the rotation speed of the driving motor.

5. A hydraulic pump that supplies hydraulic oil to a hydraulic device provided on the traveling machine body; a pump motor which is an electric motor that drives the hydraulic pump; A PTO motor which is an electric motor that drives a PTO shaft provided on the traveling machine body; A traveling motor which is an electric motor that drives the traveling machine body to travel; a common battery for supplying power to the pump motor, the PTO motor, and the driving motor; a control unit that controls distribution of electric power to the pump motor, the PTO motor, and the traveling motor; Equipped with When an overload state of the battery is detected, the control unit reduces the power supplied to the driving motor with the highest priority among the pump motor, the PTO motor, and the driving motor, an electric tractor, characterized in that if an overload state of the battery is detected even after the power supplied to the traction motor has been reduced, the control unit reduces the power supplied to the PTO motor in priority to reducing the power supplied to the pump motor.

Images