Electric tractor

Abstract

The present invention comprises: a battery for storing power for at least one among traveling and work; electric motors M1, M2 driven by receiving a supply of power from the battery; inverters 14A, 14B for converting a direct current from the battery into an alternating current and supplying the alternating current to the electric motors; and a work device support part 8 for supporting a work device so as to be attachable / detachable. The inverters 14A, 14B are adjacent to the electric motors M1, M2 on the lateral outside of a machine body in the left-right direction, and are adjacent to the work device support part 8 in the front-rear direction.

Description

electric tractor

[0001] The present invention relates to an electric tractor.

[0002] For example, in the tractor disclosed in Japanese Patent Application Laid-Open No. 2020-169553 (Patent Document 1), a front loader is attached, and the tractor has a work implement support part (referred to in the document as a "frame (11)") that detachably supports the front loader.

[0003] Japanese Patent Application Publication No. 2020-169553

[0004] When electrifying a tractor, it is necessary to install a battery to supply at least one of power for traveling and power for working to the electric motor. However, because such a battery is large and heavy, it tends to occupy a large amount of space in the electric tractor. Furthermore, to efficiently consume the power stored in the battery, it is necessary to position the electric motor and devices such as an inverter that supplies power to the electric motor so as to minimize power loss. On the other hand, the support structure for mounting a working implement tends to occupy more space than a tractor without a working implement. Therefore, securing the required space is an issue for an electric tractor that can be mounted with a working implement.

[0005] An object of the present invention is to ensure both space for a structure that supports a working implement and space for efficient equipment layout in an electric tractor that can be fitted with a working implement.

[0006] The electric tractor of the present invention comprises a battery that stores power for at least one of traveling, working, and hydraulic drive, an electric motor that is driven by power supplied from the battery, an inverter that converts direct current from the battery into alternating current and supplies the alternating current to the electric motor, and a work device support section that supports a work device so that it can be attached or detached, and is characterized in that the inverter is adjacent to the electric motor on the outer side of the body in the left-right direction and adjacent to the work device support section in the front-to-rear direction.

[0007] According to the present invention, the inverter is adjacent to the electric motor on the left and right sides. This adjacent configuration of the inverter and electric motor reduces power loss compared to a configuration in which the inverter and electric motor are not adjacent. Furthermore, because the inverter is located laterally outboard of the vehicle body relative to the electric motor, inverter maintenance is easier compared to a configuration in which the inverter is located laterally inboard of the vehicle body relative to the electric motor. Furthermore, the inverter is adjacent to the implement support unit on the front and rear sides. This makes it possible to avoid interference between the inverter and the electric motor and to construct a support structure for the implement support unit on the lateral inboard side of the vehicle body. This makes it possible to secure both space for a structure that supports the implement and space for efficient equipment layout in an electric tractor that can be fitted with an implement.

[0008] In the present invention, it is preferable that a housing frame for housing the electric motor is provided, and the inverter is supported by the housing frame.

[0009] According to this configuration, the electric motor is housed in the housing frame. Therefore, the electric motor is protected by the housing frame and is less likely to come into contact with foreign objects. Furthermore, with this configuration, the housing frame serves both to protect the electric motor and to support the inverter. This simplifies the inverter support structure compared to a configuration in which a dedicated support structure for the inverter is provided.

[0010] In the present invention, it is preferable that the inverter is provided with an electrical connection port for connecting an electrical cable to the electric motor, and that the electrical connection port is provided on the side opposite to the side on which the working device support portion is located.

[0011] With this configuration, the current carrying cable routed from the current connection port to the outside of the inverter is less likely to come into contact with the working device or the working device support portion.

[0012] In the present invention, it is preferable that the working device support portion be disposed between the battery and the electric motor in the front-rear direction.

[0013] This configuration makes it easy to avoid interference between the working device and the battery, and also makes it easy to avoid interference between the working device and the electric motor.

[0014] In the present invention, it is preferable that the working device support portion be disposed laterally outward of the vehicle body relative to the battery in the left-right direction.

[0015] This configuration makes it even easier to avoid interference between the working device and the battery.

[0016] In the present invention, it is preferable that the vehicle is provided with a driving section having a floor on which passengers board, and that the electric motor and the inverter are arranged so that their respective upper portions are positioned at the same level as or lower than the floor in the vertical direction.

[0017] With this configuration, the inverter is disposed below the floor, and the space below the floor is effectively utilized.

[0018] In the present invention, it is preferable that the driving section is provided with a boarding / alighting step for passengers to board and alight, and the inverter overlaps with the boarding / alighting step in a side view of the aircraft body.

[0019] This configuration allows the inverter to be placed below the floor in the space on the inside of the aircraft body side of the boarding / alighting steps. This allows the space below the floor to be used effectively. In addition, the boarding / alighting steps can be used both for passenger boarding and alighting and to protect the inverter.

[0020] In the present invention, it is preferable that the working device support portion is adjacent to the front side of the boarding / exiting step.

[0021] This configuration makes it easier to avoid interference between the working device and the step, and makes it even easier to avoid interference between the working device and the inverter.

[0022] In the present invention, it is preferable that a valve unit for hydraulic piping capable of connecting a hydraulic system to the hydraulic mechanism of the working device attached to the working device support part is provided, and that the valve unit is adjacent to the inverter on the outer side of the machine body and adjacent to the working device support part on the rear side of the machine body.

[0023] With this configuration, the valve unit for hydraulic piping and the implement support section are adjacent to each other in the front and rear. This makes it easier for workers to connect the hydraulic system piping from the valve unit to the hydraulic mechanism of the implement. In addition, because the valve unit is located laterally outboard of the machine body relative to the inverter, the inverter is even less likely to come into contact with foreign objects.

[0024] In the present invention, the vehicle is provided with a traveling device that is driven based on the electric power for traveling, a power transmission device that is arranged behind the electric motor and transmits power from the electric motor to the traveling device, and a reinforcing beam that is connected to each of the working device support section and the power transmission device and that reinforces the support structure of the working device support section for supporting the working device, and it is preferable that the inverter be located laterally inward of the reinforcing beam.

[0025] This configuration further strengthens the support structure for the work equipment. In addition, the reinforcing beam can also be used to protect the inverter located inside the side of the machine body.

[0026] 7 is a side view of the electric tractor; 8 is a plan view of the electric tractor; 9 is a side view of the electric tractor; 10 is a side view of the electric tractor with a front loader attached; 11 is a side view showing a battery, an electric motor, and a power transmission device; 12 is a plan view showing the arrangement of the motor and devices around it; 13 is a block diagram showing the power system and power system of the electric tractor; 14 is a plan view showing the front frame and devices arranged on the front frame; 15 is a cross-sectional view taken along line VIII-VIII in FIG. 7 showing the front frame and devices arranged on the front frame.

[0027] An embodiment of the electric tractor of the present invention will be described based on the electric tractor shown in Figures 1 to 8. In Figures 1 to 8, "F" indicates the forward direction, "B" indicates the backward direction, "U" indicates the upward direction, "D" indicates the downward direction, "R" indicates the rightward direction, and "L" indicates the leftward direction.

[0028] 1 to 3, right and left front wheels 10 are provided at the front of the machine body 1, and right and left rear wheels 11, which are the rear traveling devices, are provided at the rear of the machine body 1. The machine body 1 supports the front wheels 10 and the rear wheels 11.

[0029] The machine body 1 has a first front frame 2, a housing frame A, and a transmission case 15. The first front frame 2 is connected to the front of the housing frame A, and the transmission case 15 is connected to the rear of the housing frame A, thereby forming the frame structure of the machine body 1. Electric motors M1 and M2, which serve as power sources, are housed in the housing frame A.

[0030] A front axle case 10A is attached to the first front frame 2, and right and left front wheels 10 are attached to the front axle case 10A. The left and right front wheels 10 are supported by the front axle case 10A. The front axle case 10A extends in the left-right direction. The front axle case 10A supports the left and right front wheels 10 and houses axles that transmit power to the left and right front wheels 10. The first front frame 2 supports the front axle case 10A. The front wheels 10, front axle case 10A, and rear wheels 11 are an example of a "running device."

[0031] The transmission case 15 includes an axle case that transmits power to the left and right rear wheels 11. Therefore, the transmission case 15 supports the left and right rear wheels 11. The right and left rear wheels 11 are attached to the transmission case 15. The transmission case 15 supports the left and right rear wheels 11.

[0032] The driver's section 3, in which the operator sits, is provided above the accommodation frame A and the transmission case 15. A ROP frame 31 is attached to the transmission case 15, extends upward, and is provided at the rear of the driver's section 3. A battery 4 that supplies power to the electric motors M1, M2 is attached to the first front frame 2, and a hood 12 is provided to cover the battery 4.

[0033] The battery 4 is mounted on and supported by the first front frame 2. In other words, the first front frame 2 supports the battery 4 from below. The first front frame 2 is used to support both the battery 4 and the front axle case 10A of the front wheel 10. The battery 4 is also located above the first front frame 2. The battery 4 stores electricity for traveling, working, and hydraulic drive.

[0034] The hood 12 is configured to be openable and closable by pivoting about a horizontal axis that extends in the left-right direction of the vehicle body. When the hood 12 is in a closed state, the battery 4 is covered by the hood 12.

[0035] The electric tractor of this embodiment has two independent drive systems: a drive system for traveling and a drive system for working. Specifically, as shown in FIG. 2 , the electric tractor is equipped with an electric motor M1 for traveling and an electric motor M2 for working and hydraulic drive. The electric tractor is also equipped with two inverters 14A, 14B corresponding to the two electric motors M1, M2. The two electric motors M1, M2 are disposed on the rear side of the vehicle body relative to the battery 4. The electric motor M1 is a motor for traveling that is powered by the battery 4. The electric motor M2 is a motor for working that is powered by the battery 4. The inverters 14A, 14B are disposed laterally outward of the vehicle body relative to the electric motors M1, M2.

[0036] 1 to 3, the driver's section 3 is provided behind the battery 4 and the hood 12. The driver's section 3 is provided with a rope frame 31, a driver's seat 32, a steering wheel 33 for steering the front wheels 10, a step 34 ("boarding and alighting step"), a floor 35, a charging socket 36, a work travel operating tool 37, and a display unit 38. The driver's section 3 is supported by the housing frame A and the transmission case 15.

[0037] A footstep 34 is attached to the right side of the floor 35, and operators (passengers) mainly get on and off the driver's section 3 from the left side of the machine body 1. The operator can get on to the floor 35 of the driver's section 3 from the step 34 and sit in the driver's seat 32.

[0038] When the operator operates the steering handle 33, the left and right front wheels 10 are steered. The steering handle 33 is connected to the power steering unit 27 shown in Figure 7 via a universal joint.

[0039] Although not described in detail, the work travel operating device 37 includes an accelerator operating device for adjusting the travel speed, and operating devices for adjusting the rotation speed of the mid PTO shaft 16A and rear PTO shaft 16B, which will be described later. This allows the operator to perform various driving operations in the driving section 3. The work travel operating device 37 also has potentiometers that detect the amount of operation of the various operating devices.

[0040] The display unit 38 displays, for example, the vehicle's running state, working state, information about the battery 4 (charge level and temperature), and the like.

[0041] The charging socket 36 is provided to the right of the control handle 33 and directly above the floor 35. When an operator or the like inserts a charger adapter into the charging socket 36, the battery 4 is charged. The charging socket 36 receives power for charging the battery 4. The standard of the charging socket 36 may be, for example, CHAdeMO, CCS2, GB / T, ChaoJi, NACS, or the like.

[0042] The housing frame A, the electric motors M1, M2, the inverters 14A, 14B, and the transmission case 15 are disposed below the floor 35. The battery 4 is disposed above the floor 35. In addition, the battery 4 is provided forward of the driving unit 3 so that the rear end of the battery 4 is located forward of the front ends of the electric motors M1, M2.

[0043] 4 and 5, the storage frame A includes the front frame 6, a front wall portion 15F of the transmission case 15, a right lateral frame 5 which is the right portion, a left lateral frame 5 which is the left portion, and an upper frame 19. The front wall portion 15F of the transmission case 15 is used as both a component of the transmission case 15 and a component of the storage frame A.

[0044] The front frame 6 and the front wall portion 15F are configured as flat plates extending in the up-down and left-right directions. The front frame 6 and the front wall portion 15F extend laterally across the right and left sides of the fuselage 1. The right and left side frames 5 are configured as flat plates extending in the up-down and front-rear directions and slightly curved (see Figure 8). The front portions of the side frames 5 are connected to the right and left portions of the rear surface of the front frame 6, and the rear portions of the side frames 5 are connected to the right and left portions of the front surface of the front wall portion 15F.

[0045] An upper frame 19 extends in the left-right direction across the upper portions of the right and left lateral frames 5. The upper frame 19 is connected to the upper portions of the right and left lateral frames 5, respectively.

[0046] A flat cover 18, which is an electric motor protection member, is attached across the lower portions of the right and left lateral frames 5, which form the bottom of the storage frame A, and also across the lower portions of the front frame 6 and front wall portion 15F of the storage frame A.

[0047] In a plan view, the two electric motors M1, M2 are surrounded by the front wall portion 15F of the transmission case 15, the left and right side frames 5, and the front frame 6. The front wall portion 15F of the transmission case 15, the left and right side frames 5, the front frame 6, the cover 18, and the upper frame 19 are configured as a housing frame A for the electric motors M1, M2. In other words, the frame of the tractor of this embodiment is also configured as a housing frame A that surrounds the two electric motors M1, M2 from the front, rear, left and right, above, and below. The housing frame A houses the electric motors M1, M2. This reduces the risk of the two electric motors M1, M2 coming into contact with foreign objects.

[0048] The rear end of the first front frame 2 is connected to the front portion of the front frame 6. The front end of the lateral frame 5 is connected to the rear portion of the front frame 6. The rear end of the lateral frame 5 is connected to the front wall portion 15F of the transmission case 15. Therefore, the storage frame A is a frame body interposed between the first front frame 2 and the transmission case 15.

[0049] 1 to 5, the electric motors M1 and M2 are accommodated in the accommodation frame A. The electric motors M1 and M2 are arranged side by side below the floor 35 of the driver's section 3 and inside the accommodation frame A (between the front frame 6 and the front wall portion 15F, and between the right and left side frames 5).

[0050] 4 , the battery 4 is disposed above the floor 35 of the driving section 3, and the electric motors M1 and M2 are disposed below the floor 35. The battery 4 is disposed so that the lower part of the battery 4 is located at the same position (including approximately the same position) as the floor 35 in the vertical direction. The electric motors M1 and M2 are disposed so that the upper parts thereof are located below the floor 35 in the vertical direction. The electric motors M1 and M2 are disposed rearward of the first front frame 2.

[0051] A flange portion at the rear end of the electric motor M1 is connected with bolts to the left portion of the front surface of the front wall portion 15F of the transmission case 15, and a flange portion at the rear end of the electric motor M2 is connected with bolts to the right portion of the front wall portion 15F of the transmission case 15. In other words, the electric motors M1 and M2 are each cantilevered on the front wall portion 15F of the transmission case 15. The output shafts of the electric motors M1 and M2 are provided at the positions of the flange portions at the rear ends of the electric motors M1 and M2 and extend rearward in the fore-and-aft direction.

[0052] As shown in Figures 4 and 5, the rotational axis X1 of the electric motor M1 and the rotational axis X2 of the electric motor M2 are located at the same position in the vertical direction and extend parallel to each other in the same direction. Therefore, the output shafts of the electric motors M1 and M2 extend parallel to each other in the same direction. The front wheel transmission shaft 17 also extends along the rotational axis X1 and the rotational axis X2. That is, the electric motors M1 and M2 are disposed so that their output shafts are at the same (including substantially the same) height in the vertical direction. The electric motors M1 and M2 are disposed so that their output shafts extend parallel to each other in the same (including substantially the same) direction.

[0053] 4, the rotation axis X1 of the electric motor M1 and the rotation axis X2 of the electric motor M2 are each located at a position that overlaps in the vertical direction with the lower edge portions of the front and rear frame portions 2F of the first front frame 2. In other words, the electric motors M1, M2 are arranged so that the rotation axes X1, X2 are located at the same positions (including approximately the same positions) as the lower edge portions of the front and rear frame portions 2F in the vertical direction.

[0054] Inside the storage frame A, an electric motor M1 is provided on the left side of the recess 6a (see FIGS. 7 and 8) of the front frame 6 of the storage frame A and the center of the front wall 15F. An electric motor M2 is provided on the right side of the recess 6a of the front frame 6 of the storage frame A and the center of the front wall 15F.

[0055] The left-right width of the electric motor M1 is the same as the left-right width of the electric motor M2. In other words, the radial width of the electric motor M1 and the radial width of the electric motor M2 are the same (including approximately the same). Furthermore, the front-rear width of the electric motor M1 and the front-rear width of the electric motor M2 are the same. In other words, the width of the electric motor M1 in the direction of the rotation axis X1 and the width of the electric motor M2 in the direction of the rotation axis X2 are the same (including approximately the same). In other words, the size of the electric motor M1 and the size of the electric motor M2 are the same (including approximately the same). Furthermore, the capacity of the electric motor M1 and the capacity of the electric motor M1 are the same (including approximately the same). This facilitates reductions in the production costs and procurement costs of the electric motors M1 and M2.

[0056] The cases of the electric motors M1 and M2 are each formed cylindrically. The electric motors M1 and M2 are arranged with a gap between their respective cases. A front wheel transmission shaft 17 that transmits driving power to the front wheels 10 passes through this space (see FIGS. 4 and 8).

[0057] The power transmission device T is for transmitting power for driving to the front wheels 10. A front wheel transmission shaft 17 extends forward from the power transmission device T. The front frame 6, the first front frame 2, the front axle case 10A, and the left and right front wheels 10 are located in front of the electric motors M1 and M2. The front wheel transmission shaft 17 extends from the power transmission device T (transmission case 15) to the front axle case 10A, passing through the space between the electric motors M1 and M2, the space in the recess 6a, and the space below the first front frame 2. The front wheel transmission shaft 17 receives power for driving from the power transmission device T and transmits it to the front axle case 10A.

[0058] The front wheel transmission shaft 17 extends in the front-to-rear direction between the power transmission device T (transmission case 15) and the front axle case 10A of the front wheels 10. In other words, the electric motor M1 and the power transmission device T (transmission case 15) are disposed behind the first front frame 2, and the front wheel transmission shaft 17 extends between the power transmission device T (transmission case 15) and the front axle case 10A. In other words, in the first front frame 2, the front wheel transmission shaft 17 extends from the side where the electric motors M1, M2 are located to the front axle case 10A, and transmits power for driving to the front wheels 10.

[0059] The electric motor M1 and the electric motor M2 are disposed between the front wheels 10 and the power transmission device T. The front wheel transmission shaft 17 passes between the electric motor M1 and the electric motor M2.

[0060] [Configuration of the inverter and devices arranged laterally outboard of the machine body relative to the inverter] The right and left inverters 14A, 14B are attached to the right and left lateral frames 5 of the storage frame A. The inverter 14A is supported by the lateral frame 5 on the left side of the machine body, and the inverter 14B is supported by the lateral frame 5 on the right side of the machine body. In other words, each of the inverters 14A, 14B is supported by the storage frame A.

[0061] The battery 4 supplies power to two inverters 14A and 14B. Each of the inverters 14A and 14B receives DC current from the battery 4 and converts it into three-phase AC current.

[0062] Based on the operation of the travel operating device in the work travel operating device 37, the DC power of the battery 4 is converted to AC power in the left inverter 14A and supplied to the electric motor M1, thereby operating the electric motor M1.

[0063] Based on the operation of the work operating tool in the work traveling operating tool 37, the DC power of the battery 4 is converted into AC power in the right inverter 14B and supplied to the electric motor M2, thereby operating the electric motor M2.

[0064] The inverter 14A is disposed on the opposite side of the lateral frame 5 on the left side of the vehicle from the side where the electric motor M1 is located. The inverter 14B is disposed on the opposite side of the lateral frame 5 on the right side of the vehicle from the side where the electric motor M2 is located. In other words, the inverters 14A, 14B for the electric motors M1 and M2 are disposed on the left and right outer sides of the electric motors M1 and M2. The inverters 14A, 14B are disposed so that their upper portions are located below the floor 35 in the vertical direction.

[0065] Furthermore, the inverters 14A, 14B are each disposed behind the loader mounting portion 8. The loader mounting portion 8 and the inverters 14A, 14B are adjacent to each other in the front-to-rear direction. That is, the inverter 14A is adjacent to the electric motor M1 in the left-to-right direction, and is adjacent to the loader mounting portion 8 on the left side of the machine body in the front-to-rear direction. Furthermore, the inverter 14B is adjacent to the electric motor M2 in the left-to-right direction, and is adjacent to the loader mounting portion 8 on the right side of the machine body in the front-to-rear direction. The loader mounting portion 8 corresponds to the "work device support portion."

[0066] The inverter 14A is located laterally inward of the step 34. In other words, the inverters 14A and 14B overlap with the step 34 in a side view of the aircraft.

[0067] The inverter 14A is provided with a power connection port 14C for connecting a power cable for the electric motor M1, and the inverter 14B is provided with a power connection port 14D for connecting a power cable for the electric motor M2.

[0068] The electrical connection port 14C is provided at the rear edge of the inverter 14A, and the electrical connection port 14D is provided at the rear edge of the inverter 14B. A current cable is connected to the electrical connection port 14C, and AC power is supplied to the electric motor M1 from the current cable. A current cable is connected to the electrical connection port 14D, and AC power is supplied to the electric motor M2 from the current cable. The electrical connection ports 14C, 14D are each provided on the side opposite the side on which the loader mounting portion 8 is located. This prevents the front loader F from coming into contact with the current cables extending from the electrical connection ports 14C, 14D when the front loader F is attached to the loader mounting portion 8.

[0069] As shown in FIGS. 2 and 5 , the hydraulic piping valve unit 28 is adjacent to the inverter 14B on the outer side of the machine body and adjacent to the loader attachment portion 8 on the right side of the machine body at the rear side of the machine body. The hydraulic piping valve unit 28 is disposed on the outer side of the machine body with respect to the reinforcing beam 9 (described later). The hydraulic piping valve unit 28 may be configured to be connected and supported by the lateral frame 5 or the reinforcing beam 9. Although not shown, a hydraulic piping connector is provided at the base end of the right arm of the front loader F. The hydraulic piping extending from the valve unit 28 is connected to the hydraulic piping connector of the front loader F. In other words, the valve unit 28 is configured to connect the hydraulic system to the hydraulic mechanism of the front loader F when the front loader F is attached to the loader attachment portion 8. Note that, when a backhoe is attached to the rear of the machine body 1, the valve unit 28 may be configured to connect the hydraulic system to the hydraulic mechanism of the backhoe.

[0070] [Configuration of mounting portions for attaching working devices] As shown in Figures 5 and 8, on the right and left horizontal frames 5 of the storage frame A, upper mounting portions 5a are provided on the upper front portions of the horizontal frames 5, facing diagonally upward, and lower mounting portions 5a are provided on the lower front portions of the horizontal frames 5, facing diagonally downward.

[0071] The right loader mounting portion 8 is connected to the mounting portion 5a of the right lateral frame 5, and the left loader mounting portion 8 is connected to the mounting portion 5a of the left lateral frame 5. As will be described later, a working device such as a front loader F (see FIG. 3) is attached to the right and left loader mounting portions 8. Each of the left and right loader mounting portions 8 supports a working device such as a front loader F so that it can be attached or detached.

[0072] A loader mounting portion 8 is supported on the front portion of each of the left and right lateral frames 5. Each of the left and right loader mounting portions 8 is located laterally outward of the aircraft body relative to the lateral frames 5. Furthermore, the front end portions of each of the left and right loader mounting portions 8 are located forward of the lateral frames 5. Each of the left and right loader mounting portions 8 is adjacent to the outer lateral end portion of the front frame 6.

[0073] The loader mounting portion 8 on the left side of the machine body is adjacent to the front side of the step 34. In the front-rear direction, the loader mounting portion 8 is disposed between the front wheel 10 and the step 34. In addition, the loader mounting portion 8 is disposed between the battery 4 and the electric motors M1, M2 in the front-rear direction. The loader mounting portion 8 is disposed laterally outward of the battery 4 on the machine body in the left-right direction.

[0074] When the front loader F is mounted on the electric tractor, as shown in FIG. 3 , the base end of the front loader F is connected to the loader mounting portion 8. At this time, the front end of the reinforcement beam 9 is connected to the base end of the front loader F. The base end of the front loader F is sandwiched between the loader mounting portion 8 and the front end of the reinforcement beam 9 in the left-right direction. The left and right reinforcement beams 9 extend forward and rearward, and their respective rear ends are supported by the axle cases of the rear wheels 11 in the transmission case 15. The left and right reinforcement beams 9 cover the transmission case 15 from the lateral outer side of the vehicle body to the front and rear. This configuration enhances durability against moment loads of the front loader F. In other words, the left and right reinforcement beams 9 are connected to the loader mounting portion 8 and the power transmission device T, respectively, and reinforce the support structure of the loader mounting portion 8 that supports the front loader F. The inverters 14A, 14B are located laterally inward of the vehicle body relative to the left and right reinforcement beams 9.

[0075] 4 and 5, the electric tractor is provided with first front frames 2 on the right and left sides of the body. The first front frames 2 are connected to the upper part of the front surface of the front frame 6 of the storage frame A and extend forward.

[0076] 4 , the second front frame 7 is connected to the front-rear center portion of the first front frame 2 and the lower portion of the front frame 6. At the lower portion of the front surface of the front frame 6 of the storage frame A, the rear portion of the second front frame 7 is connected to the lower portion of the first front frame 2. The front portion of the second front frame 7 is connected to the front-rear center portion of the first front frame 2.

[0077] A battery 4 is attached to the upper part of the first front frame 2, with the rear end of the battery 4 located forward of the front ends of the electric motors M1, M2. A front axle case 10A is attached in a rollable manner to the lower front part of the first front frame 2 at the center from front to back and the center from left to right. The first front frame 2 can roll relative to the left and right front wheels 10. The front axle case 10A (front wheels 10) is located below the battery 4 and forward of the electric motors M1, M2.

[0078] A flat cover 7P is attached across the right and left second front frames 7. In a side view of the aircraft, the front portions of the second front frame 7 and the cover 7P are higher than the rear portions of the second front frame 7 and the cover 7P. In other words, the second front frame 7 and the cover 7P are inclined with their fronts raised.

[0079] The rear end of the first front frame 2 is connected to the upper part of the front frame 6. The first front frame 2, the front frame 6, and the second front frame 7 form a triangular frame in a side view of the vehicle, thereby strengthening the frame structure at the front of the tractor vehicle.

[0080] The left and right first front frames 2, the left and right second front frames 7, and the cover 7P all have the same left-right width W2. The left-right width W1 of the storage frame A is greater than the left-right width W2 of the left and right first front frames 2, the left and right second front frames 7, and the cover 7P.

[0081] In a plan view, the rotation axis X1 of the electric motor M1 is adjacent to the first front frame 2 on the left side of the machine body 1 and the second front frame 7 on the left side of the machine body in the left-right direction of the machine body 1. Furthermore, the rotation axis X2 of the electric motor M2 is adjacent to the first front frame 2 on the right side of the machine body and the second front frame 7 on the right side of the machine body in the left-right direction of the machine body 1. As a result, the left-right width W2 of the left and right first front frames 2, the left and right second front frames 7, and the cover 7P is approximately the same as the left-right width (distance) of the rotation axes X1, X2 of the output shafts of the electric motors M1, M2.

[0082] 6, the power transmission device T is provided with a power transmission mechanism 15A for traveling, a power transmission mechanism 15B for working, and a hydraulic pump 15C. The transmission case 15 houses the power transmission mechanism 15A for traveling, the power transmission mechanism 15B for working, and the hydraulic pump 15C. In other words, the power transmission device T has the transmission case 15, the power transmission mechanism 15A for traveling, the power transmission mechanism 15B for working, and the hydraulic pump 15C.

[0083] The driving power transmission mechanism 15A receives rotational power from the electric motor M1 and transmits the rotational power to the left and right front wheels 10 and the left and right rear wheels 11 while changing the speed using a gear-type transmission mechanism. As a result, the left and right front wheels 10 and the left and right rear wheels 11 are driven to rotate by the driving power from the electric motor M1. In other words, the driving power transmission mechanism 15A transmits the driving power from the electric motor M1 to the front wheels 10 and the rear wheels 11. In other words, the left and right front wheels 10 and the left and right rear wheels 11 are driven based on the driving power.

[0084] The electric tractor is also equipped with a mid-PTO shaft 16A and a rear PTO shaft 16B. The work power transmission mechanism 15B receives rotational power from the electric motor M2 and distributes the rotational power to the mid-PTO shaft 16A and the rear PTO shaft 16B. This causes the mid-PTO shaft 16A and the rear PTO shaft 16B to rotate.

[0085] If a work device is connected to the mid PTO shaft 16A or the rear PTO shaft 16B, the work device is driven by the rotational power of the mid PTO shaft 16A or the rear PTO shaft 16B. In other words, the work power transmission mechanism 15B transmits work power from the electric motor M2 to the mid PTO shaft 16A and the rear PTO shaft 16B. The mid PTO shaft 16A and the rear PTO shaft 16B then supply the work power to the work device.

[0086] The hydraulic pump 15C receives rotational power from the electric motor M2 and is driven to rotate. The hydraulic pump 15C is the drive source for the hydraulic system of the electric tractor. For example, if a front loader F is attached to the tractor, the hydraulic pump 15C pumps hydraulic oil, and the front loader F operates based on the hydraulic pressure of the hydraulic oil. In other words, the hydraulic pump 15C supplies hydraulic pressure for work to the work implement.

[0087] In this way, the power transmission device T is used for transmitting power for traveling, power for working, and hydraulic drive. In other words, the power transmission device T is provided with a power transmission mechanism 15A for traveling that transmits power from the electric motor M1 to the front wheels 10 and rear wheels 11, a power transmission mechanism 15B for working that transmits power from the electric motor M2 to the mid PTO shaft 16A and rear PTO shaft 16B, and a hydraulic pump 15C for hydraulic drive. The power transmission device T is also disposed behind the electric motors M1 and M2.

[0088] The work implement connected to the mid PTO shaft 16A may be, for example, a grass cutter, a rotary rake, a leaf cutter, a spreader, etc. The mid PTO shaft 16A may also be used as a front PTO shaft for a work implement attached to the front of the machine body 1. The work implement connected to the rear PTO shaft 16B may be a cultivator, a seed sowing implement, a planter, a fertilizer applicator, a leaf cutter, a spreader, a grass cutter, a baler, a mulcher, a stone picker, a rotary rake, a tedder, a towed harvester and sorter, a top pinching implement, a tillage management implement, a ridge forming implement, etc.

[0089] [Regarding the drive system of the electric tractor] As shown in Figure 6, the electric tractor is provided with a control device 20 that controls the drive of the electric motors M1, M2 in response to the operation of the work travel operating device 37. The control device 20 is a core element of the control system of the electric tractor, and is configured as a collection of multiple ECUs.

[0090] The control device 20 is connected to the charge / discharge control unit 4A of the battery 4, the inverters 14A and 14B, the electric motors M1 and M2, the charge control unit 22, the DC / DC converter 23, the work travel operating tool 37, the display unit 38, etc., via a signal harness 21 of the CAN (Controller Area Network) type, for example, so as to be able to communicate data.

[0091] The control device 20 outputs command signals to the inverters 14A, 14B in response to commands from the work traveling operating device 37. The inverter 14A controls the output of the electric motor M1 by adjusting the three-phase AC power (voltage value, frequency, current value, etc.) supplied from the battery 4 to the electric motor M1 in response to the command signal from the control device 20. Similarly, the inverter 14B controls the output of the electric motor M2 by adjusting the three-phase AC power supplied from the battery 4 to the electric motor M2 in response to the command signal from the control device 20.

[0092] The control device 20 controls the operation of the display unit 38. Therefore, the display unit 38 displays the operating status of the electric motors M1, M2, information about the battery 4, and the like.

[0093] The battery 4 is, for example, a lithium-ion battery. Although not shown, the battery 4 is configured by stacking a large number of small, low-voltage unit cells. The output voltage of the battery 4 is, for example, 400 volts. The unit cells are housed in a storage case. These unit cells are sealed in the storage case.

[0094] The battery 4 is electrically connected to the power distribution unit 13. The power distribution unit 13 is also electrically connected to each of the inverters 14A, 14B and the DC / DC converter 23. Therefore, the power distribution unit 13 functions as a hub that distributes power from the battery 4 to each of the inverters 14A, 14B and the DC / DC converter 23. The power distribution unit 13 is also connected to the charging socket 36 via the charging control unit 22. The power distribution unit 13 is configured to receive charging power from the charging socket 36 and transmit it to the battery 4.

[0095] The battery 4 is provided with a charge / discharge control unit 4A. The charge / discharge control unit 4A is configured to control the discharge current and charge current of the battery 4 based on the output voltage, receiving voltage, heat generation temperature, etc. of the battery 4.

[0096] Because the battery 4 outputs a large amount of power to the inverters 14A and 14B, the amount of heat generated by the battery 4 also increases. Temperature management is also important to properly manage the charge and discharge amounts of the battery 4. For this reason, a water-cooled temperature control flow path is installed inside the battery 4. A battery temperature control device 25 is provided near the battery 4 to supply liquid refrigerant to this temperature control flow path.

[0097] The battery temperature control device 25 includes a battery radiator 25A, a reservoir tank 25B, a battery heater 25C, and a pump 25D. Refrigerant is stored in the reservoir tank 25B. The pump 25D pumps the refrigerant that cools the battery 4. The battery heater 25C heats the refrigerant, thereby raising the temperature of the battery 4. When the pump 25D is operating, the refrigerant circulates from the reservoir tank 25B through the battery heater 25C, the pump 25D, a temperature control flow path inside the battery 4, and the battery radiator 25A in this order. In this way, the battery temperature control device 25 is configured to regulate the temperature of the battery 4.

[0098] The battery heater 25C is provided between the pump 25D and the inlet of the temperature control flow path inside the battery 4. When the temperature of the battery 4 is low, the current for charging and discharging the battery 4 is low. When the electric tractor is started in this state, the charge / discharge control unit 4A operates the battery heater 25C to heat the refrigerant. This allows the temperature of the battery 4 to quickly rise to a temperature appropriate for charging and discharging.

[0099] The battery radiator 25A is provided between the outlet of the temperature control flow path inside the battery 4 and the reservoir tank 25B. Therefore, the refrigerant heated in the temperature control flow path inside the battery 4 is cooled by the battery radiator 25A and returned to the reservoir tank 25B.

[0100] The circuit of the charging control unit 22 is electrically connected to both the charging socket 36 and the power distribution unit 13. The charging control unit 22 may be, for example, a power module or PLC (Programmable Logic Controller) having a microcomputer that executes a program based on a control signal from the control device 20, or may be a relay circuit that operates based on an electrical signal from the control device 20. The charging control unit 22 controls the charging voltage and charging current for the battery 4 when charging the battery 4 (including rapid charging). The charging control unit 22 adjusts the power received from the charging socket 36 and supplies it to the battery 4 as charging power.

[0101] In addition to the battery 4, the electric tractor is equipped with an electrical equipment battery 24 that supplies power to the control device 20 and other electrical equipment. The electrical equipment battery 24 is, for example, a lead battery. The electrical equipment battery 24 supplies low-voltage (for example, 12 volts) power to drive the electrical equipment. The output voltage of the electrical equipment battery 24 is lower than the output voltage of the battery 4.

[0102] The electrical component battery 24 is charged with power supplied from the battery 4 via the DC / DC converter 23. The DC / DC converter 23 can reduce the voltage of the battery 4 to the voltage of the electrical component battery 24 and then supply power to the low-voltage electrical components. The DC / DC converter 23 can also supply power to the electrical component battery 24. In other words, the DC / DC converter 23 is electrically connected to both the battery 4 and the electrical component battery 24, and can receive power from the battery 4, reduce the voltage, and transmit the power to the electrical component battery 24. This allows the battery 4 to supply power to the electrical component battery 24 and charge it. In other words, the electrical component battery 24 can be charged with power received from the battery 4 via the DC / DC converter 23.

[0103] High-power equipment that receives high-voltage power from the battery 4 tends to become hot due to heat generation. For this reason, the electric tractor is equipped with a high-voltage equipment cooling system 26 for cooling the high-power equipment. The high-voltage equipment cooling system 26 includes a high-voltage equipment radiator 26A and pumps 26B and 26C. The pumps 26B and 26C are connected in series. The pumps 26B and 26C pump a refrigerant that cools the high-power equipment that operates on electric power, such as the inverters 14A and 14B, the electric motors M1 and M2, and the DC / DC converter 23. When the pumps 26B and 26C are operating, the refrigerant flows through the cooling passages of the high-power equipment, such as the inverters 14A and 14B, the electric motors M1 and M2, and the DC / DC converter 23, to cool the high-power equipment. The refrigerant heated by the high-power equipment is then cooled by the high-voltage equipment radiator 26A. The order of the cooling passages in the high-power device can be changed as appropriate.

[0104] [Reinforcement Structure for Battery Support in Front Frames] As described above, the battery 4 is supported by the first front frame 2 and the second front frame 7. As shown in Figures 7 and 8, the first front frame 2 includes left and right front and rear frame sections 2F, left and right inner reinforcing frames 2R, left and right auxiliary frames 2H, a cover 2P, and a connecting plate 2T. The front and rear frame section 2F on the right side of the vehicle supports a right portion of the battery 4 from below. The front and rear frame section 2F on the left side of the vehicle supports a left portion of the battery 4 from below. Although not shown, the left and right front and rear frame sections 2F support the front axle case 10A in a rolling manner via cross-bridge frames that are connected to the left and right front and rear frame sections 2F and extend left and right. In other words, the left and right front and rear frame sections 2F are used to support both the battery 4 and the front axle case 10A.

[0105] The front and rear frame sections 2F extend along the fore-and-aft direction of the vehicle body 1, and the front axle case 10A is located below the fore-and-aft central section of the front and rear frame sections 2F. In other words, the front and rear frame sections 2F extend in the fore-and-aft direction while supporting the front axle case 10A at the fore-and-aft central section.

[0106] The weight of the battery 4 tends to increase as the capacity of the battery 4 increases. As shown in Figures 5, 7, and 8, in this embodiment, the inner reinforcing frame 2R on the left side of the vehicle is connected to the rear of the front and rear frame section 2F on the left side of the vehicle, and the inner reinforcing frame 2R on the right side of the vehicle is connected to the rear of the front and rear frame section 2F on the right side of the vehicle. In Figures 7 and 8, the left and right inner reinforcing frames 2R are shown surrounded by thick lines.

[0107] The rear end of the inner reinforcing frame 2R is connected to the front frame 6 extending laterally. Each of the left and right inner reinforcing frames 2R is connected across its front and rear portions to the adjacent front and rear frame portions 2F on the outer lateral side of the aircraft. In other words, the front and rear frame portions 2F are supported across the front and rear portions of the inner reinforcing frame 2R.

[0108] The left and right inner reinforcing frames 2R are located laterally inward of the left and right front and rear frame portions 2F of the first front frame 2. In other words, the left and right front and rear frame portions 2F of the first front frame 2 are located laterally outward of the inside reinforcing frame 2R.

[0109] Each of the left and right inner reinforcement frames 2R is formed so that it becomes thicker toward the rear. In other words, each of the left and right inner reinforcement frames 2R is formed so that its width in the left-right direction of the fuselage 1 becomes wider toward the rear (the side where the front frame 6 is located). The rear portion of each of the left and right inner reinforcement frames 2R extends lower in the up-down direction than the front portion. In other words, each of the left and right inner reinforcement frames 2R is formed so that its rear portion is thicker in the up-down direction than the front portion. In this way, each of the left and right inner reinforcement frames 2R is connected to the adjacent front-rear frame portion 2F on the outer lateral side of the fuselage and reinforces the support structure of the battery 4.

[0110] Each of the left and right inner reinforcing frames 2R is provided with an extension portion 2s. The extension portion 2s is formed on the upper portion of each of the left and right inner reinforcing frames 2R, and the extension portion 2s extends laterally inward of the aircraft body along the left-right direction of the aircraft body. A flat connecting plate 2T is connected to this extension portion 2s. This configuration increases the rigidity of the rear portion of the first front frame 2.

[0111] The front end of the inner reinforcing frame 2R is located rearward of the front axle case 10A. The front portion of the inner reinforcing frame 2R overlaps with the front portion of the second front frame 7 in the front-to-rear direction. Auxiliary frames 2H are provided at the locations where the front portion of the inner reinforcing frame 2R and the front portion of the second front frame 7 are located. The auxiliary frames 2H are connected to each of the front and rear frame portions 2F, the inner reinforcing frame 2R, and the second front frame 7. In other words, the front portion of the inner reinforcing frame 2R and the front portion of the second front frame 7 are connected to each other via the auxiliary frames 2H. This strengthens the support structure at the rear of the first front frame 2.

[0112] 7 and 8 , in this embodiment, pumps 26B, 26C and battery heater 25C are disposed in the space between the battery 4 and the front axle case 10A and between the left and right front and rear frame portions 2F of the first front frame 2. The pumps 26B, 26C and battery heater 25C are disposed vertically between the battery 4 and the front wheel transmission shaft 17 extending in the front-to-rear direction. The pumps 25D, pumps 26B, 26C and battery heater 25C are disposed below the battery 4 and on the front side of the vehicle body with respect to the electric motors M1, M2.

[0113] The refrigerant pumps 25D and 26B are each bolted to the front and rear frame portion 2F on the left side of the aircraft body. The pump 26C is bolted to the second front frame 7 on the left side of the aircraft body. The pump 26B is located behind the pump 25D, and the pump 26C is located behind the pump 26B. The power steering unit 27 is located to the right of the pump 25D.

[0114] The battery heater 25C, pump 25D, and pump 26B are each disposed between the left and right front and rear frame sections 2F in the left-right direction. Furthermore, the battery heater 25C, pump 25D, and pump 26B are each disposed between the upper and lower edges of the front and rear frame section 2F on the left side of the vehicle and between the upper and lower edges of the front and rear frame section 2F on the right side of the vehicle in the up-down direction. In this state, a cover 2P is connected to the lower edges of the left and right front and rear frame sections 2F. The cover 2P covers the area below the battery 4 and the space between the left and right front and rear frame sections 2F from below. Therefore, the pump 25D is surrounded on all sides by the left and right front and rear frame sections 2F, the battery 4, and the cover 2P. This makes it less likely for the pump 25D to come into contact with foreign objects in the up-down and left-right directions.

[0115] The battery heater 25C is fixed to the underside of the connecting plate 2T with bolts. That is, the battery heater 25C is supported by the left and right inner reinforcing frames 2R via the connecting plate 2T. Also, a pump 25D is disposed in front of the first front frame 2. That is, the battery heater 25C and pump 25D of the battery temperature regulator 25 are supported by the first front frame 2.

[0116] The battery heater 25C and the pumps 25D, 26B are disposed between the left and right inner reinforcement frames 2R in the left-right direction, and are located between the upper and lower edges of the left and right inner reinforcement frames 2R in the up-down direction. The battery heater 25C and the pumps 25D, 26B are also disposed between the battery 4 and the front axle case 10A in the up-down direction. In addition, the battery heater 25C and the pump 26B are disposed between the electric motors M1, M2 and the front axle case 10A in the front-rear direction.

[0117] The pump 26C is disposed so as to be located above the lower edges of the left and right second front frames 7. In this state, a cover 7P is connected to each of the lower edges of the left and right second front frames 7. The cover 7P covers the area below the battery 4 and the space between the left and right second front frames 7 from below. With this configuration, the pumps 26B, 26C and the battery heater 25C are surrounded on all sides by the left and right front and rear frame portions 2F, the left and right second front frames 7, the battery 4, the connecting plate 2T, and the cover 7P. This makes it less likely that the pumps 26B, 26C and the battery heater 25C will come into contact with foreign objects in the vertical and horizontal directions.

[0118] Other Embodiments The present invention is not limited to the configurations exemplified in the above-described embodiments, and other representative embodiments of the present invention will be exemplified below.

[0119] (1) In the above-described embodiment, the battery 4 stores power for traveling, working, and hydraulic drive. This is not limiting, and for example, the battery 4 supported by the first front frame 2 may be configured to store power for at least one of traveling, working, and hydraulic drive. In this case, a battery that stores power other than the at least one of these may be disposed elsewhere in the electric tractor.

[0120] (2) In the above-described embodiment, the electric motor M1 for traveling and the electric motor M2 for working and hydraulic drive are provided. However, the present invention is not limited to this embodiment, and a configuration may be adopted in which only one of the electric motors M1, M2 is provided and one of the electric motors M1, M2 is used for traveling, working, and hydraulic drive.

[0121] (3) The front end of the front loader F as a working device may be configured to be able to mount a bucket, a container bucket, a pallet fork, a bale fork, a bale grab, a grader, etc. The working device may also be, for example, a spreader, a soil sample collection device, etc.

[0122] (4) In the above embodiment, the loader attachment portion 8 is disposed in front of the inverters 14A, 14B, but the loader attachment portion 8 may be disposed behind the inverters 14A, 14B. In this case, the loader attachment portion 8 may be disposed behind the electric motors M1, M2, or may be disposed at the rear of the machine body like a so-called skid steer loader.

[0123] (5) The above-mentioned reinforcing beam 9 may not be provided.

[0124] (6) Although the charging socket 36 is provided to the right of the control handle 33 as described above, the charging socket 36 may be provided to the left of the control handle 33 .

[0125] (7) In the above-described embodiment, the "traveling device" is the front wheel 10, the front axle case 10A, and the rear wheel 11. However, without being limited to this embodiment, the "traveling device" may be a wheel mechanism having a crawler (including a semi-crawler). For example, at least one of the front wheel 10 and the rear wheel 11 may be a wheel mechanism having a crawler.

[0126] (8) In the above-described embodiment, the electric motor M2 is used for both work and hydraulic drive. However, the present invention is not limited to this embodiment, and the electric motor M2 may be configured to be used for either work or hydraulic drive.

[0127] The configurations disclosed in the above-described embodiments (including other embodiments, the same applies hereinafter) can be applied in combination with the configurations disclosed in other embodiments, unless a contradiction occurs. Furthermore, the embodiments disclosed in this specification are merely examples, and the present invention is not limited to these, and can be modified as appropriate within the scope of the purpose of the present invention.

[0128] The present invention is applicable to electric tractors.

[0129] 3: Driving unit 4: Battery 8: Loader mounting section (working device support section) 9: Reinforcement beam 10: Front wheels (traveling device) 10A: Front axle case (traveling device) 11: Rear wheels (traveling device) 14A: Inverter 14B: Inverter 14C: Power connection port 14D: Power connection port 28: Valve unit 34: Step (boarding / exiting step) 35: Floor 36: Charging socket A: Storage frame M1: Electric motor M2: Electric motor T: Power transmission device

Claims

1. A battery for storing electric power for at least one of traveling, working, and hydraulic driving; an electric motor driven by receiving electric power supply from the battery; an inverter that converts a direct current from the battery into an alternating current and supplies the alternating current to the electric motor; and a working device support portion that supports a working device so as to be detachable. The inverter is adjacent to the electric motor on the outer side of the machine body in the left-right direction and adjacent to the working device support portion in the front-rear direction, which is an electric tractor.

2. An accommodation frame for accommodating the electric motor is provided, and the inverter is supported by the accommodation frame. The electric tractor according to claim 1.

3. The inverter is provided with an energization connection port for connecting an energization cable to the electric motor, and the energization connection port is provided on the side opposite to the side where the working device support portion is located. The electric tractor according to claim 1 or 2.

4. The working device support portion is disposed between the battery and the electric motor in the front-rear direction. The electric tractor according to any one of claims 1 to 3.

5. The working device support portion is disposed on the outer side of the machine body in the left-right direction relative to the battery. The electric tractor according to any one of claims 1 to 4.

6. A driving portion having a floor on which a rider rides is provided, and the electric motor and the inverter are disposed such that their upper parts are located at the same level as or below the floor in the vertical direction. The electric tractor according to any one of claims 1 to 5.

7. The driving portion is provided with a boarding and alighting step for a rider to board and alight, and the inverter overlaps the boarding and alighting step in a side view of the machine body. The electric tractor according to claim 6.

8. The working device support portion is adjacent to the front side of the boarding and alighting step. The electric tractor according to claim 7.

9. The working device support portion is provided with a valve unit for hydraulic piping that can connect a hydraulic system to a hydraulic mechanism of the working device mounted thereon. The valve unit is adjacent to the inverter on the outer side of the machine body and adjacent to the working device support portion on the rear side of the machine body. The electric tractor according to any one of claims 1 to 8.

10. A traveling device that is driven based on the power for traveling, a power transmission device that is disposed behind the electric motor and transmits the power from the electric motor to the traveling device, and a reinforcing beam that is connected to each of the work device support portion and the power transmission device and reinforces the support structure of the work device support portion for supporting the work device. The inverter is located inside the machine widthwise direction more than the reinforcing beam. The electric tractor according to any one of claims 1 to 9.