Power-operated work vehicle

Abstract

To avoid an increase in internal pressure of an exterior case caused by a heating component when airtightness in the exterior case is improved to avoid entry of dust and rain water.SOLUTION: An electric work vehicle includes: a battery; an electric motor; an inverter disposed on an electric power supply path from the battery to the electric motor; and a travel device which is driven by the electric motor. The inverter includes an exterior case 5 in which a substrate including an inverter circuit is installed. The exterior case 5 is supported by a machine body frame, and a breathing hole 7 which may discharge internal air of the exterior case 5 is provided on a rear-facing wall part of the exterior case 5.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to an electric work vehicle including a battery, a motor driven by power supplied from the battery, and a traveling device driven by the motor. [Background technology]

[0002] A known example of such an electric work vehicle is described in Patent Document 1. This electric work vehicle (referred to as a "tractor" in Patent Document 1) is equipped with an inverter device (referred to as an "inverter" in Patent Document 1) in the power supply path from the battery to the electric motor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-953 Summary of the Invention [Problem to be solved by the invention]

[0004] The structure shown in Patent Document 1 is a fairly sturdy support structure that is made up of a large inverter support section that spans the left and right aircraft frames and a battery support base that is relatively sturdy in order to support a large battery. The inverter device is attached to this sturdy inverter support section. However, the mounting structure of the inverter device to the inverter support portion and the specific configuration of the inverter device itself are not disclosed. For this reason, there is room for improvement in terms of preventing an increase in internal case pressure due to heat-generating components within an inverter device when the airtightness of the exterior case is increased to prevent the intrusion of dust and rainwater from the outside, and in terms of simplifying assembly and disassembly during maintenance.

[0005] The present invention aims to provide an electric work vehicle that can prevent an increase in internal case pressure due to heat-generating components when the airtightness of the exterior case is increased to prevent the intrusion of dust and rainwater. [Means for solving the problem]

[0006] The features of the electric work vehicle of the present invention are as follows: A battery; an electric motor supplied with power from the battery; an inverter device disposed in a power supply path from the battery to the electric motor; A traveling device driven by the electric motor, The inverter device includes an exterior case in which a substrate having an inverter circuit is mounted, The exterior case is supported by an aircraft frame, a ventilation hole capable of discharging internal air of the exterior case is provided in a wall portion of the exterior case on a rear side of the aircraft body, a battery mounting stand for mounting the battery is fixed to the aircraft frame; The exterior case is detachably attached to the aircraft frame separately from the battery mounting stand. 、 The exterior case is disposed below the battery mounting base. The reason is that...

[0007] According to the present invention, the outer case is provided with a ventilation hole through which the air inside the outer case can be exhausted. Therefore, even if the internal air is heated by heat-generating components such as a board equipped with an inverter circuit inside the outer case and the pressure inside the case increases, exhaust is possible through the ventilation hole, thereby preventing the inside of the case from becoming abnormally high temperature and pressure. At the same time, since the ventilation hole is provided in the wall of the exterior case on the rear side of the fuselage, it is easy to prevent dust and rainwater from the outside from entering the exterior case through the ventilation hole. According to the configuration of the present invention, the outer case is removably attached to the body frame separately from the battery mounting base, so that by disconnecting it from the body frame, it becomes easier to remove the inverter device itself and perform maintenance work.

[0008] In the present invention, it is preferable that the ventilation hole is provided with a filter that allows internal air to be discharged as the air pressure inside the exterior case increases.

[0009] With this configuration, in addition to the ventilation hole being provided in the wall portion of the outer case on the rear side of the body, the ventilation hole is equipped with a filter, which makes it even easier to prevent dust and rainwater from the outside from entering the interior of the outer case.

[0010]

[0011]

[0012] In the present invention, it is preferable that an input connection portion to which an input harness from the battery can be detached and an output connection portion to which an output harness for the electric motor can be detached are provided on the outside of the exterior case.

[0013] According to this configuration, when removing or attaching the inverter device itself, the input connection portion where the input harness from the battery can be removed and the output connection portion where the output harness can be removed and attached are provided on the outside of the outer case, making it easy to operate from the outside and also easy to remove and attach the inverter device itself. [Brief description of the drawings]

[0014] [Figure 1] FIG. [Diagram 2] FIG. 2 is an explanatory diagram showing a power transmission mechanism from a battery to a traveling device, a working device, etc. [Diagram 3] FIG. 2 is a block diagram showing a power transmission system from a motor to a traveling device and the like. [Figure 4] FIG. 4 is a partially cutaway side view showing an installation location of an inverter. [Diagram 5] FIG. 4 is a front view showing a cross section of the machine frame and the battery mounting base, and illustrating the mounting location of the inverter. [Figure 6] FIG. 4 is a plan view showing a cross section of the battery mounting base and illustrating mounting locations of an inverter. [Figure 7] 2 is a plan view showing a case body in an exterior case of the inverter. FIG. [Figure 8] FIG. [Figure 9] FIG. [Figure 10] 2 is a bottom view showing a case body of the exterior case. FIG. [Figure 11] FIG. 4 is a bottom view showing a case lid of the exterior case. [Figure 12] 7 is a cross-sectional view taken along line XII-XII in FIG. 6. [Figure 13] 7 is a cross-sectional view taken along line XIII-XIII in FIG. 6. [Figure 14] 4 is an enlarged cross-sectional view in a vertical direction showing a return portion of the case lid. FIG. [Figure 15] FIG. 4 is an enlarged cross-sectional view showing a ventilation hole in a plan view. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The embodiment of the present invention will be described with reference to the drawings. In the following description, unless otherwise specified, the direction of the arrow F in the drawing is "forward", the direction of the arrow B is "backward", the direction of the arrow L is "left", and the direction of the arrow R is "right". Also, the direction of the arrow U in the drawing is "upward", and the direction of the arrow D is "downward".

[0016] [Overall configuration of the tractor] The tractor of this embodiment will be described below. As shown in Fig. 1, the tractor has left and right front wheels 10, left and right rear wheels 11, and a cover member 12.

[0017] The tractor also includes a machine body frame 2 and a driving section 3. The machine body frame 2 is supported by left and right front wheels 10 and left and right rear wheels 11.

[0018] The cover member 12 is disposed at the front of the vehicle body. The driver's section 3 is provided behind the cover member 12. In other words, the cover member 12 is disposed in front of the driver's section 3.

[0019] The driving section 3 has a protective frame 30, a driving seat 31, and a steering wheel 32. An operator can sit in the driving seat 31. This allows the operator to get into the driving section 3. The left and right front wheels 10 are steered by operating the steering wheel 32. The operator can perform various driving operations in the driving section 3.

[0020] The tractor is equipped with a traveling battery 4. The cover member 12 is configured to be swingable about an opening / closing axis Q that runs along the left-right direction of the vehicle body. This allows the cover member 12 to be opened and closed. When the cover member 12 is in a closed state, the traveling battery 4 is covered by the cover member 12.

[0021] As shown in Fig. 2, the tractor includes an inverter 14 (corresponding to an inverter device) and a motor M. The driving battery 4 supplies power to the inverter 14. The inverter 14 converts DC power from the driving battery 4 into AC power and supplies it to the motor M. The motor M is then driven by the AC power supplied from the inverter 14.

[0022] 2 and 3, the tractor is equipped with a hydrostatic continuously variable transmission 15 and a transmission 16. As shown in Fig. 3, the hydrostatic continuously variable transmission 15 has a hydraulic pump 15a and a hydraulic motor 15b.

[0023] The hydraulic pump 15a is driven by rotational power from the motor M. When the hydraulic pump 15a is driven, the rotational power is output from the hydraulic motor 15b. The hydrostatic continuously variable transmission 15 is configured so that the speed of the rotational power is changed between the hydraulic pump 15a and the hydraulic motor 15b. The hydrostatic continuously variable transmission 15 is also configured so that the gear ratio can be changed steplessly.

[0024] The rotational power output from the hydraulic motor 15b is transmitted to the transmission 16. The rotational power transmitted to the transmission 16 is changed in speed by a gear-type speed change mechanism of the transmission 16, and distributed to the left and right front wheels 10 and the left and right rear wheels 11. In this way, the left and right front wheels 10 and the left and right rear wheels 11 are driven.

[0025] 2 and 3, the tractor is equipped with a mid PTO shaft 17 and a rear PTO shaft 18. The rotational power output from the motor M is distributed to the hydraulic pump 15a, the mid PTO shaft 17, and the rear PTO shaft 18. This causes the mid PTO shaft 17 and the rear PTO shaft 18 to rotate.

[0026] If a working device is connected to the mid PTO shaft 17 or the rear PTO shaft 18, the working device is driven by the rotational power of the mid PTO shaft 17 or the rear PTO shaft 18. For example, as shown in Fig. 2, in this embodiment, a grass cutting device 19 is connected to the mid PTO shaft 17. The grass cutting device 19 is driven by the rotational power of the mid PTO shaft 17. [Battery and inverter mounting structure]

[0027] 4 and 5, the vehicle frame 2 has left and right front-rear frames 2A and a horizontal frame 2B. The left and right front-rear frames 2A extend along the front-rear direction of the vehicle, and the horizontal frame 2B connects the left and right front-rear frames 2A to each other. The horizontal frame 2B connects the left and right front-rear frames 2A at the lower parts of the left and right front-rear frames 2A, and extends in the front-rear direction across the area where the front end of the inverter 14 is located and the area where the front end of the motor M is located in a plan view.

[0028] An axle unit 10F is connected to the horizontal frame 2B and extends to the left and right of the vehicle body. Front wheels 10 are rotatably supported at both left and right ends of the axle unit 10F. A propeller shaft 13 is connected to the transmission 16 and the axle unit 10F and extends in the fore-and-aft direction of the vehicle body below the horizontal frame 2B.

[0029] The inverter 14 and the motor M are disposed adjacent to each other in the front-rear direction. In other words, the inverter 14 and the motor M are disposed side by side along the front-rear direction of the vehicle body. The motor M and the inverter 14 are supported by the left and right front-rear frames 2A side by side along the front-rear direction of the vehicle body and positioned between the left and right front-rear frames 2A. The inverter 14 is positioned in front of the motor M.

[0030] The inverter 14 and the motor M are connected by a power supply cable 21. One end 21A of the power supply cable 21 is detachably connected to the output connector 14C of the inverter 14, and the opposite end 21B of the power supply cable 21 is detachably connected to the power receiving connector 22 of the motor M. The output connector 14C is provided in a state where it is located in an area of ​​the exterior case 5 opposite to the side where the motor M is located. The power supply cable 21 is located above the horizontal frame 2B and is housed in the space between the left and right front and rear frames 2A. In other words, the power supply cable 21 extends in the front and rear direction within the space surrounded by the left and right front and rear frames 2A, the horizontal frame 2B, and the bottom plate portion 50 of the exterior case 5. This prevents the output connector 14C and the power supply cable 21 from coming into contact with foreign objects, and also reduces the risk of the output connector 14C and the power supply cable 21 coming into contact with foreign objects and becoming disconnected.

[0031] The driving battery 4 is supported by the left and right front and rear frames 2A in a state where it is located directly above the inverter 14. Specifically, as shown in Figures 4 to 6, left and right support surface portions 23 are formed on the upper end portions of each of the left and right front and rear frames 2A. Battery mounting stands 24 are placed on the left and right support surface portions 23, and the driving battery 4 is placed on the battery mounting stands 24.

[0032] The left and right support surface portions 23 extend laterally of the aircraft at the upper end portions of the left and right front-rear frames 2A. As shown in Figs. 4 and 5, triangular ribs 27, 27 are interposed between the support surface portions 23 and the front-rear frames 2A so that the left and right support surface portions 23 do not bend relative to the left and right front-rear frames 2A. The triangular ribs 27, 27 are fixed by welding at their abutting ends to the front-rear frames 2A and the support surface portions 23, so that the support surface portions 23 are integrated with the front-rear frames 2A via the triangular ribs 27, 27 and form a part of the aircraft frame 2. The bottom of the inverter 14 and the support surface portions 23 are connected by mounting bolts 28. Thus, the inverter 14 is supported on the aircraft frame 2 in a detachable manner.

[0033] The battery mounting base 24 is connected with bolts to each of the left and right support surface portions 23. As shown in Fig. 4 to Fig. 6, the battery mounting base 24 is a member assembled by welding a mounting plate 24C overlapping a portion of the left and right support surface portions 23, a vertical frame 24A made of C-shaped steel erected on the mounting plate 24C, left and right angle steels 24B extending in the fore-and-aft direction of the airframe at the upper ends of the left and right vertical frames 24A, and a horizontal angle steel (not shown) connecting the left and right angle steels 24B extending in the fore-and-aft direction of the airframe to each other.

[0034] The mounting plate 24C has bolt insertion holes 24Ca for bolt-connecting the mounting plate 24C and the support surface portion 23, and the mounting plate 24C and the support surface portion 23 can be connected and fixed via connecting bolts 26. The battery mounting base 24 is formed in a gate shape when viewed in the front-rear direction of the aircraft. The battery mounting base 24 covers the inverter 14 from above and from the left and right sides.

[0035] Both left and right sides of the upper part of the angle steel 24B are bolted to the lower part of the connecting plate 25. Also, both left and right sides of the lower part of the driving battery 4 are bolted to the upper part of the connecting plate 25. In this way, the driving battery 4 and the battery mounting base 24 are connected via the connecting plate 25.

[0036] [About inverters] The inverter 14 of this embodiment will be described with reference to Figures 4 to 15. The inverter 14 converts a direct current from the driving battery 4 into an alternating current and supplies it to the motor M.

[0037] As shown in Figures 7, 12 and 13, the inverter 14 is configured by incorporating a board 60 having an inverter circuit 6, a capacitor 61, etc., in an exterior case 5 having a case body 5A and a case lid 5B. The inverter circuit 6 is a circuit body that converts DC current from the driving battery 4 into AC current, and includes an inverter module made up of, for example, insulated gate bipolar transistors (IGBTs), and an inverter control module that communicates with a host electronic control unit (ECU) to control the inverter module. A capacitor 61 keeps the supply voltage to the inverter module constant.

[0038] The board 60 includes a first board 60A on which an inverter module is provided, and a second board 60B on which an inverter control module is provided. 12 and 13, a first board fastening portion 51 for fastening the first board 60A is provided on the bottom plate portion 50 of the case body 5A. A second board fastening portion 52 for fastening a second board 60B, which is a board 60 separate from the first board 60A, is provided at a location overlapping the upper portion of the first board 60A.

[0039] The first substrate fastening portion 51 includes a protruding pedestal 53 for receiving the peripheral and central portions of the first substrate 60A and connecting and fixing the same to the bottom plate portion 50. With the protruding pedestal 53 positioned at a position facing the peripheral and central portions of the first substrate 60A, the peripheral and central portions of the first substrate 60A can be fixed to the bottom plate portion 50 using screw holes and set screws provided in the protruding pedestal 53.

[0040] The second board fastening portion 52 includes a mounting plate 62 capable of supporting the peripheral and central portions of the second board 60B, and a protruding pedestal 53 for receiving the peripheral portion of the mounting plate 62 and connecting and fixing it to the bottom plate portion 50. With the peripheral and central portions of the second board 60B supported by the mounting plate 62 and the protruding pedestal 53 positioned at a position facing the peripheral portion of the mounting plate 62, the mounting plate 62 is fixed to the bottom plate portion 50 using screw holes and set screws provided in the protruding pedestal 53.

[0041] As shown in Fig. 7 and Fig. 15, in some of the protruding pedestals 53, adjacent protruding pedestals 53 are connected to each other by a connecting rib 54. The connecting rib 54 is formed to connect the protruding pedestals 53 that protrude upward from the bottom plate portion 50 for fixing the mounting plate 62 to the bottom plate portion 50, among the protruding pedestals 53, with a high protruding height from the bottom plate portion 50, and to connect the protruding pedestals 53 with the inner surface of the case main body 5A described later. This makes it easy to effectively suppress the shaking of the protruding pedestals 53 that protrude high from the bottom plate portion 50. As a result, it is easy to reduce shaking and vibration of the mounting plate 62 and the second board 60B fixed to the mounting plate 62.

[0042] The driving battery 4 and the inverter 14 are electrically connected by a power cable 20 (corresponding to an input harness). A direct current flows through the power cable 20. As shown in Figures 4 and 6, the inverter 14 is provided with an input connector 14B (corresponding to an input connection part). The input connector 14B protrudes forward beyond the front surface of the exterior case 5 and is electrically connected to a connection port 20A of the power cable 20.

[0043] Thus, the inverter 14 has an input connector 14B that is electrically connected to the power cable 20, an inverter circuit 6 that converts DC current to AC current, and an output connector 14C (output connection part) that is electrically connected to the power supply cable 21 (corresponding to an output harness).

[0044] [Outer case] The exterior case 5 is an aluminum die-cast product that includes a rectangular box-shaped case body 5A and a rectangular plate-shaped case lid 5B. The rectangular box-shaped case body 5A includes a bottom plate portion 50 and a peripheral wall portion 55, and the upper portion of the space surrounded by the bottom plate portion 50 and the peripheral wall portion 55 is open to form an upward opening. The case lid 5B is configured to be connectable and disconnectable to the upper end portion of the case body 5A so that the opening of the case body 5A can be opened and closed.

[0045] A first board stopper 51 and a second board stopper 52 for fixing the board 60 are provided on the bottom plate 50 of the case body 5A. With the first board 60A and the second board 60B attached to the first board stopper 51 and the second board stopper 52, the inverter circuit 6 is fitted inside the exterior case 5 by closing the opening of the case body 5A with the case lid 5B.

[0046] [Case body] As shown in Figures 8 and 9, a lattice-shaped reinforcing rib 56 consisting of vertical ribs 55a extending in the up-down direction and horizontal ribs 55b extending in the horizontal direction is formed on the outer wall surface of the peripheral wall portion 55 of the case body 5A. 7, the reinforcing rib 56 is formed so that the vertical ribs 55a and the horizontal ribs 55b do not protrude outward beyond the outer periphery of the upper end of the peripheral wall portion 55. The outer wall surface located between adjacent vertical ribs 55a is formed into a recessed wall surface having recessed portions 55c at various locations that recess closer to the inner wall surface of the case body 5A than the locations where the vertical ribs 55a are present. In other words, as shown in Figures 7 to 9, 12 and 13, the vertical ribs 55a and the horizontal ribs 55b are not formed to protrude outward from the outer peripheral edge of the upper end of the peripheral wall portion 55, but rather, they are left as reinforcing ribs 56 by forming the peripheral wall portion 55 so that a portion of the outer wall surface is recessed by providing a recessed portion 55c.

[0047] 7 and 13, a screw hole 55d into which a connecting bolt 57 can be screwed for screwing the case lid 5B in a state where the case lid 5B faces the opening of the case body 5A is formed at the upper end of the peripheral wall 55. As shown in Figs. 7 and 8, the screw hole 55d is formed at a position overlapping with the vertical rib 55a in a side view. In this manner, the screw holes 55d are formed at the locations where the vertical ribs 55a are present, thereby making effective use of the locations where the vertical ribs 55a are present, which are the locations where the horizontal thickness of the peripheral wall portion 55 of the case body 5A is thick, thereby increasing the strength at the connection points between the case lid 5B and the case body 5A.

[0048] 7, 12, and 13, the recessed portion 55c has a depth equivalent to the distance d1 from the outer end to the inner end of the vertical rib 55a. As a result, the innermost part of the recessed portion 55c is formed closer to the inner wall surface of the peripheral wall portion 55 than the location of the connecting bolt 57. By increasing the recessed depth of the recessed portion 55c in this manner, the thickness of the peripheral wall portion 55 at the location of the recessed portion 55c is reduced, thereby reducing the weight of the case body 5A.

[0049] The lattice-shaped reinforcing ribs 56 are similarly formed on the peripheral wall portion 55 of the case body 5A not only on the left side surface shown in FIG. 8 and the rear surface shown in FIG. 9, but also on the front surface shown in FIG. 5 and on the right side surface (not shown).

[0050] As shown in FIG. 10, reinforcing ribs 56 are formed on the lower surface of the bottom plate portion 50 of the case body 5A, the reinforcing ribs 56 being made up of front-rear ribs 50a extending in the front-rear direction and left-right ribs 50b extending in the left-right direction. Mounting seats 50d for fixing the case body 5A to the support surface 23 of the front / rear frame 2A are provided on both left and right ends of the bottom plate portion 50. Mounting holes 50e for fixing the case body 5A via mounting bolts 28 are provided in the mounting seats 50d.

[0051] The front-rear ribs 50a and the left-right ribs 50b are not formed to protrude downward from the underside of the mounting seat 50d provided at the lower end of the outer peripheral edge of the bottom plate portion 50, but are formed by providing an upward recessed portion 50c in the area surrounded by the front-rear ribs 50a and the left-right ribs 50b. The recessed depth of the upward recessed portion 50c corresponds to the distance d2 from the lower end to the upper end of the front-rear rib 50a and the left-right rib 50b. The distance d2 is shorter than the distance d1 (see FIG. 13) corresponding to the recessed depth of the recessed portion 55c in the peripheral wall portion 55 described above, and the recessed portion 50c is formed shallower than the recessed portion 55c.

[0052] [Breathing hole] Of the peripheral wall portion 55 of the case main body 5A, a rearward wall portion 55R facing the rear side of the aircraft is provided with a ventilation hole 7 for discharging the internal air of the exterior case 5. This ventilation hole 7 is equipped with a filter 70 to allow the internal air to be discharged as the air pressure inside the exterior case 5 increases due to heat generation in the inverter circuit 6, etc., while restricting the intrusion of dust, rainwater, etc. from the outside.

[0053] 5 and 9, the exterior case 5 is mounted on the front / rear frames 2A in a state where it is distributed to the left and right of a vertical line CL passing through the center position in the left / right direction of the left and right front / rear frames 2A, that is, the center position in the left / right direction of the vehicle. The vertical line CL is a vertical line that intersects with the front / rear axis (not shown) of the axle unit 10F of the front wheel 10 when viewed in the front / rear direction of the vehicle. Therefore, the exterior case 5 is mounted on the front / rear frames 2A near a location where the front / rear frames 2A sway in the left / right direction is the least when the front wheel 10 rolls around the front / rear axis.

[0054] 4 and 5, the driving battery 4 is located above the exterior case 5, and the upper side of the exterior case 5 is covered by the driving battery 4 and a battery mounting stand 24 on which the driving battery 4 is mounted. Below the exterior case 5 are horizontal frames 2B that connect the left and right front and rear frames 2A to each other, and support surface portions 23 provided on the upper edges of the front and rear frames 2A. As a result, the lower side of the exterior case 5 is blocked by the left and right horizontal frames 2B and the support surface portions 23. Although the vertical frames 24A of the battery mounting stand 24 are present on the outer left and right sides of the exterior case 5, a wide range of the outer left and right sides of the exterior case 5 is open laterally outward.

[0055] The ventilation hole 7 provided in the rear wall portion 55R is located between the left and right front and rear frames 2A in the left-right direction. More specifically, as shown in Fig. 9, it is located between the vertical line CL and the right front and rear frame 2A.

[0056] [Case lid] The case lid 5B, which can be connected to and disconnected from the upper end of the case body 5A, is configured as follows.

[0057] 11, the case lid 5B has a number of bolt insertion holes 58a (corresponding to connecting holes) formed in the peripheral portion of a rectangular cover plate material 58. Connecting bolts 57 are inserted through the bolt insertion holes 58a and through a number of screw holes 55d formed in the upper end portion of the peripheral wall portion 55 of the case body 5A, and the case lid 5B can be screwed in a state in which it faces the opening of the case body 5A.

[0058] As shown in Figs. 11 to 14, the outer peripheral end of the cover plate material 58 is formed with a rib-like return portion 58b that protrudes downward along the outer peripheral edge of the cover plate material 58. This return portion 58b is formed so that the front-to-rear length and left-to-right length of the inner surface of the return portion 58b are slightly larger than the front-to-rear length and left-to-right length of the outer surface of the upper end of the peripheral wall portion 55 so that it can be fitted onto the upper end of the peripheral wall portion 55.

[0059] 12 to 14, with the cover plate 58 placed on the upper side of the peripheral wall 55 of the case body 5A, the return portion 58b is fitted in a state where it partially overlaps the upper end of the peripheral wall 55 in the vertical direction. With the case lid 5B fitted over the peripheral wall 55 of the case body 5A in this manner, the contact point between the upper end of the peripheral wall 55 of the case body 5A and the lower surface of the case lid 5B at a position opposite to the upper end is located at a higher position than the lower end of the return portion 58b corresponding to the lower periphery of the case lid 5B. In this state, by inserting and tightening a connecting bolt 57 into the bolt insertion hole 58a of the cover plate material 58 and the screw hole 55d of the peripheral wall portion 55, the case cover 5B is connected and fixed in a fitted state to the upper end portion of the peripheral wall portion 55 of the case main body 5A.

[0060] As shown in Figures 11 and 14, a resin gasket 8 is interposed between the upper end of the peripheral wall portion 55 of the case body 5A and the outer peripheral end portion inside the return portion 58b of the cover plate material 58 as a sealing material that also serves as a cushioning material. As described above, the point of contact between the upper end of the peripheral wall portion 55 of the case body 5A and the underside of the case lid 5B at the position opposite to that upper end is located higher than the lower end of the return portion 58b which corresponds to the lower peripheral portion of the case lid 5B, and therefore the position of the gasket 8 interposed at this point is also located higher than the lower end of the return portion 58b which corresponds to the lower peripheral portion of the case lid 5B.

[0061] 11, the gasket 8 has a through hole 8a through which the connecting bolt 57 can be inserted, at the same position as the bolt insertion hole 58a of the cover plate material 58. When the gasket 8 is interposed between the upper end of the peripheral wall portion 55 and the outer circumferential end portion of the cover plate material 58 that is located more inward than the return portion 58b and then connected and fixed by the connecting bolt 57, the return portion 58b prevents dust and rainwater from entering from the outside, and the sealing effect of the gasket has a synergistic effect to easily and reliably prevent dust and rainwater from entering the exterior case 5. Furthermore, the gasket 8 is also effective in suppressing the propagation of vibration from the case body 5A to the case lid 5B side, and conversely, from the case lid 5B to the case body 5A side.

[0062] The upper surface of the cover plate material 58 which becomes the case lid 5B is formed in a flat surface almost entirely except for the periphery of the bolt insertion holes 58a as shown in Fig. 6, while the lower surface of the cover plate material 58 is formed with a large number of reinforcing ribs 56 as shown in Fig. 11. These reinforcing ribs 56 are diagonal lattice-shaped ribs 59a, 59b which extend along the diagonal direction of the cover plate material 58.

[0063] In FIG. 11, the portion surrounded by the diagonal lattice-shaped ribs 59a, 59b forms an upward recessed portion 59c that recesses into the upper surface side of the case lid 5B. That is, the lower surface of the cover plate material 58 located between the diagonal lattice-shaped ribs 59a, 59b is not formed to protrude downward from the lower end of the return portion 58b as shown in Figures 12 and 13, but is formed as a recessed wall surface provided with recesses 59c at various points that recess toward the upper surface of the cover plate material 58. In this way, the diagonal lattice-shaped ribs 59a, 59b are left as reinforcing ribs 56 by forming the recesses 59c so that parts of the lower surface of the cover plate material 58 are recessed.

[0064] The depth of the upward recessed portion 59c corresponds to the distance d3 from the lower end to the upper end of the diagonal lattice-shaped ribs 59a, 59b. This distance d3 is shorter than the distance d1 (see FIG. 13) corresponding to the depth of the recessed portion 55c in the peripheral wall portion 55 described above, and the recessed portion 50c is formed shallower than the recessed portion 55c.

[0065] The diagonal lattice-shaped ribs 59a, 59b are formed along a direction connecting the bolt insertion holes 58a formed in the rectangular peripheral portion of the case lid 5B.

[0066] As shown in FIG. 11, in part of the lower surface of the case lid 5B (the inner surface of the outer case 5), there is an area S1 where the diagonal lattice-shaped ribs 59a, 59b protruding into the space inside the outer case 5 are not present. In this region S1, the diagonal lattice-shaped ribs 59a, 59b extending in the direction connecting the bolt insertion holes 58a are interrupted midway from one bolt insertion hole 58a to the other bolt insertion hole 58a. In this region S1, the diagonal lattice-shaped ribs 59a, 59b do not exist, so that the innermost surface of region S1 (the lower surface of case lid 5B) is closer to the upper surface of case lid 5B by the protruding height of the diagonal lattice-shaped ribs 59a, 59b, and is located at a position approximately the same as the recess depth of recessed portion 59c. This region S1 is provided so as to form an insulation distance securing space between the case lid 5B and the components attached to the case body 5A at a location opposite the location of the region S1, making it easier to secure an insulation distance.

[0067] A striking projection 58c that partially projects outward from the outer periphery of the cover plate 58 is integrally formed in the case cover 5B by casting. The striking protrusions 58c protrude horizontally outward from between bolt insertion holes 58a (corresponding to bolt holes) formed around the outer periphery of the cover plate material 58. The striking protrusions 58c are also formed with ribs 58d (corresponding to reinforcing ribs 56) along the protruding direction of the striking protrusions 58c (see FIGS. 6 and 9).

[0068] The striking protrusion 58c tightly connects the case lid 5B to the case main body 5A by tightening the connecting bolt 57. If the case is not opened or closed for a long period of time, the case lid 5B may become stuck to the upper end of the case main body 5A even if the connecting bolt 57 is removed, making it difficult to open. At this time, striking the striking protrusion 58c from the outside breaks the tight contact between the case lid 5B and the case body 5A, making it easier to open the case lid 5B. Since the striking protrusion 58c is an aluminum die-cast product, striking it from the outside may cause some deformation or damage depending on the degree of the strike, but there is little risk of deformation or damage to the case lid 5B portion, which is a major component of the exterior case 5 other than the striking protrusion 58c.

[0069] In order to effectively eliminate the adhesion between the case lid 5B and the upper end of the peripheral wall 55 by striking the striking protrusion 58c from the outside, it is preferable that the fitting portion between the case lid 5B and the upper end of the peripheral wall 55 is configured as follows: That is, it is preferable that the size of the inner peripheral surface of the return portion 58b formed on the outer periphery of the case lid 5B is set so that the inner peripheral surface of the return portion 58b can be separated from the outer peripheral surface of the upper end of the peripheral wall 55 so that there is a slight horizontal gap between the inner peripheral surface of the return portion 58b formed on the outer periphery of the case lid 5B and the outer peripheral surface of the upper end of the peripheral wall 55 as shown in Figures 12 to 14.

[0070] [Another embodiment] Other embodiments are described below. The following embodiments may be used in combination unless a contradiction occurs. The scope of the present invention is not limited to the contents of these embodiments.

[0071] (1) In the above-described embodiment, the exterior case 5 is an aluminum die-cast product. However, the exterior case 5 does not necessarily have to be an aluminum die-cast product. For example, the exterior case 5 may be a cast iron product or may be made of other materials. The other configurations may be the same as those of the above-described embodiment.

[0072] (2) In the above-described embodiment, an example was given of a structure in which two boards 60 are housed inside the outer case 5 as an inverter circuit. However, the number of boards 60 is not limited to two, and may be one, or three or more. The other configurations may be the same as those of the above-described embodiment.

[0073] (3) In the above-described embodiment, an example was given of an outer case 5 having a structure composed of a rectangular box-shaped case body 5A and a rectangular plate-shaped case lid 5B. However, the shape of the outer case 5 is not limited to a rectangular shape, and various shapes can be adopted. The other configurations may be the same as those of the above-described embodiment.

[0074] (4) In the above-described embodiment, a structure in which lattice-shaped reinforcing ribs 56 are formed on the entire peripheral wall portion 55 and bottom plate portion 50 of the case body 5A is exemplified, but this structure is not necessarily required, and it is also acceptable for the reinforcing ribs 56 to be formed on only a portion of the peripheral wall portion 55 and bottom plate portion 50 of the case body 5A. The other configurations may be the same as those of the above-described embodiment.

[0075] (5) In the above-described embodiment, a structure in which similar lattice-shaped reinforcing ribs 56 are formed on the entire peripheral wall portion 55 and bottom plate portion 50 of the case body 5A is exemplified. However, this structure is not necessarily required. For example, the reinforcing ribs 56 may be formed in any appropriate combination, such as by forming vertical ribs 55a on the peripheral wall portions 55 on both the left and right sides, forming horizontal ribs 55b on the front and rear peripheral wall portions 55, and forming front and rear ribs 50a on the underside of the bottom plate portion 50. Furthermore, the extending direction of the reinforcing ribs 56 is not limited to the up-down, horizontal, front-back, or left-right directions, but may be set appropriately to face diagonally or in any other direction. The other configurations may be the same as those of the above-described embodiment.

[0076] (6) In the above embodiment, the reinforcing rib 56 has a structure in which the recessed portion 55c is formed in a direction recessed from a reference wall surface such as the outer peripheral edge of the upper end of the peripheral wall portion 55, but the structure is not necessarily limited to this. For example, the reinforcing rib 56 may protrude laterally outward from a reference wall surface such as the outer peripheral edge of the upper end of the peripheral wall portion 55. Moreover, the exterior case 5 may have a structure in which a part of the wall does not have the reinforcing ribs 56 . The other configurations may be the same as those of the above-described embodiment.

[0077] (7) In the above embodiment, the reinforcing ribs 56 formed on the underside of the cover plate material 58 are provided with the ribs 59a, 59b in a diagonal lattice shape along the diagonal direction of the cover plate material 58, but the present invention is not necessarily limited to this structure. For example, the reinforcing ribs 56 may be in a lattice shape in which the front-rear direction and the left-right direction cross each other along the periphery of the cover plate material 58, rather than in a diagonal direction. Also, instead of a lattice shape, the reinforcing ribs 56 may be in a diagonal direction along the diagonal direction of the cover plate material 58, in a front-rear direction along the periphery of the cover plate material 58, or in a left-right direction along the periphery of the cover plate material 58. The other configurations may be the same as those of the above-described embodiment.

[0078] (8) In the above embodiment, the reinforcing ribs 56 are formed only on the lower surface of the cover plate 58, but the present invention is not limited to this structure. For example, the reinforcing ribs 56 may be formed only on the upper surface of the cover plate 58, or the reinforcing ribs 56 may be formed on both the lower and upper surfaces of the cover plate 58, or any other suitable structure may be used. The other configurations may be the same as those of the above-described embodiment.

[0079] (9) In the above-described embodiment, a structure using connecting ribs 54 that connect the protruding pedestals 53 with a high upward protruding height among the multiple protruding pedestals 53 used as board fastening portions is exemplified. However, the present invention is not necessarily limited to this structure. For example, the present invention may be configured to connect protruding pedestals 53 with a low protruding height together, or to connect high and low protruding pedestals. The other configurations may be the same as those of the above-described embodiment.

[0080] (10) In the above-described embodiment, a structure in which the ventilation hole 7 is provided at only one location on the rear-facing wall portion 55R of the outer case 5 is exemplified. However, this structure is not necessarily limited to this structure. For example, the ventilation hole 7 may be provided at multiple locations on the rear-facing wall portion 55R of the outer case 5. The other configurations may be the same as those of the above-described embodiment.

[0081] (11) In the above-described embodiment, a structure in which the ventilation hole 7 is provided only in the rear-facing wall portion 55R of the outer case 5 is exemplified. However, the present invention is not necessarily limited to this structure. For example, the ventilation hole 7 may be provided in, in addition to the rear-facing wall portion 55R of the outer case 5, also in a peripheral wall portion 55 other than the rear-facing wall portion 55R. The other configurations may be the same as those of the above-described embodiment. [Industrial Applicability]

[0082] The present invention can be used not only in tractors, but also in various electric work vehicles such as combine harvesters, rice transplanters, and construction machines. [Explanation of symbols]

[0083] 2 Aircraft frame 4 Battery 5 Outer case 5A Case body 5B Case lid 6 Inverter Circuit 7 Breathing hole 10,11 Running gear 14 Inverter 14B Input connection 14C Output Connection 20 Input harness 21 Output harness 24 Battery Mounting Stand 50 Bottom plate part 55 Peripheral wall part 60 Substrates M Electric motor

Claims

1. A battery; an electric motor supplied with power from the battery; an inverter device disposed in a power supply path from the battery to the electric motor; A traveling device driven by the electric motor, The inverter device includes an exterior case in which a substrate having an inverter circuit is mounted, The exterior case is supported by an aircraft frame, a ventilation hole capable of discharging internal air of the exterior case is provided in a wall portion of the exterior case on a rear side of the aircraft body, a battery mounting stand for mounting the battery is fixed to the aircraft frame; the exterior case is detachably attached to the aircraft frame separately from the battery mounting stand, The electric work vehicle has the exterior case disposed below the battery mounting base.

2. 2. The electric work vehicle according to claim 1, wherein the ventilation hole is provided with a filter that allows internal air to be discharged as the air pressure inside the exterior case increases.

3. 2. The electric work vehicle according to claim 1, further comprising an input connection section on the outside of the exterior case to which an input harness from the battery can be detached, and an output connection section to which an output harness for the electric motor can be detached.

Images