electric work vehicle

Abstract

To effectively cool a component of an inverter.SOLUTION: An inverter 14 contains a loading plate 50A, and includes: an inverter case 50 onto which a sealed space is formed; a capacitor 51 that is held by the loading plate 50A in the sealed space; a power transistor 52 that is held by the loading plate 50A in the sealed space; a resistance 53 that is held by the loading plate 50A in the sealed space; and an inverter coolant passage 55 that is provided to an inner part of the loading plate 50A, and is circulated in the inverter 14 to flow a coolant for cooling the capacitor 51, the power transistor 52, and the resistance 53. The power transistor 52 includes a heat sink, and the inverter coolant passage 55 includes an open hole penetrated to the sealed space. The heat sink penetrates the open hole to be projected into the inverter coolant passage 55.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to an electric work vehicle in which a traveling device is driven by a motor. [Background technology]

[0002] Electric work vehicles use a motor to drive their travelling gear. The three-phase current (three-phase AC) that drives the motor is generated by an inverter. The inverter is equipped with power transistors such as IGBTs that generate three-phase AC at a specified frequency. Since the IGBTs generate a lot of heat when in operation, they are cooled by a refrigerant.

[0003] For example, as shown in Patent Document 1, an IGBT (power transistor) is cooled by a laminated cooler through which a refrigerant passes. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-152637 Summary of the Invention [Problem to be solved by the invention]

[0005] However, inverters also have capacitors, resistors, etc. in addition to IGBTs, and these components must be cooled. There is also a demand for more efficient cooling of inverter components, including IGBTs.

[0006] An object of the present invention is to efficiently cool inverter components. [Means for solving the problem]

[0007]

[0008]

[0009]

[0010]

[0011]

[0012] In order to achieve the above object, another electric work vehicle according to an embodiment of the present invention comprises a vehicle body, a traveling device provided on the vehicle body, a motor that drives the traveling device, an inverter that supplies power to the motor, a radiator that cools a refrigerant, and a cooling path in which the refrigerant cooled by the radiator circulates around at least the inverter and back to the radiator, the inverter including a mounting plate and an inverter case that forms an enclosed space, a capacitor that is held on the mounting plate within the enclosed space and smooths input direct current, and a power transistor that is held on the mounting plate within the enclosed space and converts the direct current supplied from the capacitor into three-phase alternating current of a predetermined frequency. the power transistor has a heat sink, the inverter refrigerant flow path has a through hole that passes through the inverter refrigerant flow path toward the sealed space, the heat sink passes through the through hole and protrudes into the inverter refrigerant flow path, and the inverter refrigerant flow path has a protrusion where the mounting plate protrudes toward the power transistor in a region that overlaps with the position of the power transistor in the inverter refrigerant flow path.

[0013] With this configuration, the capacitors, power transistors, and resistors mounted on the inverter are efficiently cooled by heat exchange with the refrigerant via the mounting plate of the inverter case. The heat sink of the power transistor protrudes into the inverter coolant flow path through the through-hole in the mounting plate. This configuration allows the heat sink to come into direct contact with the coolant, efficiently dissipating and cooling the power transistor, which generates a large amount of heat. With this configuration, the inverter coolant flow path narrows toward the power transistor in the protruding region of the heat sink, which is the position of the inverter coolant flow path that cools the power transistor. As a result, the coolant flows while being in precise contact with the heat sink, and the coolant flow rate is increased, allowing the power transistor to be cooled efficiently.

[0014] In order to achieve the above object, another electric work vehicle according to an embodiment of the present invention comprises a vehicle body, a traveling device provided on the vehicle body, a motor that drives the traveling device, an inverter that supplies power to the motor, a radiator that cools a refrigerant, and a cooling path in which the refrigerant cooled by the radiator circulates around at least the inverter and back to the radiator, the inverter including a mounting plate and an inverter case that forms an enclosed space, a capacitor that is held on the mounting plate within the enclosed space and smooths input direct current, and a capacitor that is held on the mounting plate within the enclosed space and converts the direct current supplied from the capacitor into three-phase alternating current of a predetermined frequency. a power transistor for replacing the capacitor, a resistor held by the mounting plate within the sealed space and discharging power from the inverter; and an inverter refrigerant flow path provided inside the mounting plate and through which the refrigerant circulates inside the inverter to cool the capacitor, the power transistor, and the resistor, the power transistor having a heat sink, the inverter refrigerant flow path having a through hole penetrating toward the sealed space, the heat sink penetrating the through hole and projecting into the inverter refrigerant flow path, the inverter refrigerant flow path having a refrigerant reservoir in an inflow region of the refrigerant, the cross-sectional area of ​​the refrigerant reservoir being larger than the cross-sectional area of ​​the other inverter refrigerant flow paths.

[0015] With this configuration, the capacitors, power transistors, and resistors mounted on the inverter are efficiently cooled by heat exchange with the refrigerant via the mounting plate of the inverter case. The heat sink of the power transistor protrudes into the inverter coolant flow path through the through-hole in the mounting plate. This configuration allows the heat sink to come into direct contact with the coolant, efficiently dissipating and cooling the power transistor, which generates a large amount of heat. With this configuration, the refrigerant that flows into the inverter refrigerant flow path is temporarily stored in the refrigerant reservoir, and a sufficient amount of refrigerant is then discharged into the inverter refrigerant flow path, thereby accurately filling the inverter refrigerant flow path with refrigerant and efficiently cooling components such as capacitors, power transistors, and resistors.

[0016] In order to achieve the above object, another electric work vehicle according to an embodiment of the present invention comprises a vehicle body, a traveling device provided on the vehicle body, a motor that drives the traveling device, an inverter that supplies power to the motor, a radiator that cools a refrigerant, and a cooling path through which the refrigerant cooled by the radiator circulates around at least the inverter and back to the radiator, the inverter including a mounting plate and an inverter case that forms an enclosed space, a capacitor that is held on the mounting plate within the enclosed space and smooths input direct current, and a DC current that is held on the mounting plate within the enclosed space and supplied from the capacitor. to three-phase AC of a predetermined frequency, a resistor held by the mounting plate within the sealed space and discharging the power of the inverter, and an inverter refrigerant flow path provided inside the mounting plate through which the refrigerant circulates inside the inverter to cool the capacitor, the power transistor, and the resistor, the power transistor having a heat sink, the inverter refrigerant flow path having a through hole penetrating toward the sealed space, the heat sink penetrating the through hole and protruding into the inverter refrigerant flow path, and the refrigerant cools the capacitor, the power transistor, and the resistor in that order.

[0017] With this configuration, the capacitors, power transistors, and resistors mounted on the inverter are efficiently cooled by heat exchange with the refrigerant via the mounting plate of the inverter case. The heat sink of the power transistor protrudes into the inverter coolant flow path through the through-hole in the mounting plate. This configuration allows the heat sink to come into direct contact with the coolant, efficiently dissipating and cooling the power transistor, which generates a large amount of heat. Generally, capacitors have lower heat resistance than power transistors. Power transistors generate more heat during operation than capacitors. Resistors are less likely to fail due to heat than capacitors or power transistors, so they require less cooling. In addition, refrigerants cool objects by exchanging heat with them. Furthermore, because power transistors generate a lot of heat, the cooling capacity of the refrigerant decreases after cooling the power transistors. For these reasons, it is preferable to cool capacitors first. In addition, it is preferable for the refrigerant to cool the capacitors before cooling the power transistors.

[0018] Therefore, by forming the inverter refrigerant flow path so that the refrigerant cools the capacitor, power transistor, and resistor in that order, the capacitor, power transistor, and resistor can be cooled efficiently and in a balanced manner.

[0019] A temperature sensor for measuring the temperature of the refrigerant may be provided in the inverter refrigerant flow path between a position where the capacitor is cooled and a position where the power transistor is cooled.

[0020] As mentioned above, it is preferable to cool the capacitor first. Furthermore, since the power transistor generates a large amount of heat, it is important to manage the temperature of the coolant flowing through the power transistor in order to sufficiently cool the power transistor.

[0021] Therefore, if the temperature of the refrigerant after cooling the capacitor is too high, it can be determined that the capacitor may not be sufficiently cooled, and if the temperature of the refrigerant is sufficiently low, it can be determined that the capacitor is sufficiently cooled.Furthermore, if the temperature of the refrigerant after cooling the capacitor is too high, it can be determined that the capacitor is not sufficiently cooled, or that there is a risk that the power transistor may not be sufficiently cooled.

[0022] As described above, by measuring the temperature of the refrigerant flowing between the capacitor and the power transistor in the inverter refrigerant flow path, the cooling efficiency of the capacitor and the power transistor can be confirmed, and the capacitor and the power transistor can be cooled efficiently.

[0023] For example, if the measured refrigerant temperature is approximately room temperature, it is determined that the capacitor generates little heat or is sufficiently cooled, and that the power transistor can be accurately cooled. Therefore, control can be performed to reduce or stop the flow of refrigerant. Also, if the measured refrigerant temperature is above a predetermined temperature, control can be performed to increase the flow of refrigerant, and if necessary, control can be performed to stop the operation of the inverter. The inverter preferably includes an O-ring that seals the gap between the outer periphery of the power transistor and the inner periphery of the through hole. This configuration improves the sealing performance between the power transistor and the inverter case, and prevents the refrigerant from leaking into the inverter case through the through-hole. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 2 is a left side view of the tractor. [Figure 2] FIG. [Figure 3] FIG. 2 is a left side view illustrating the arrangement of an inverter and the like. [Figure 4] FIG. 2 is a diagram illustrating a flow of power transmission. [Figure 5] FIG. 2 is a plan view illustrating a schematic configuration of a cooling path. [Figure 6] FIG. 2 is a front view illustrating an example of a main part of a motor arrangement configuration. [Figure 7]FIG. 2 is a perspective view illustrating a schematic configuration of a motor coolant flow path. [Figure 8] FIG. 2 is a plan view illustrating a main configuration of an inverter. [Figure 9] 9 is a cross-sectional left side view showing a main part of the cross section taken along line IX-IX in FIG. 8. [Figure 10] FIG. 2 is a bottom view illustrating the configuration of an IGBT. [Figure 11] 10 is a cross-sectional left side view showing a main part of the cross section taken along the line XI-XI in FIG. 8. DETAILED DESCRIPTION OF THE INVENTION

[0025] An embodiment of the present invention will be described with reference to the drawings. In the following description, unless otherwise specified, the direction of arrow F in the drawings will be referred to as "front," the direction of arrow B as "rear," the direction of arrow U as "up," the direction of arrow D as "down," the direction of arrow L as "left," and the direction of arrow R as "right."

[0026] [Overall configuration of the tractor] The following describes an electric tractor (hereinafter simply referred to as a tractor) as an example of an electric work vehicle. As shown in Figures 1 and 2, the tractor has left and right front wheels 10, left and right rear wheels 11, and a cover member 12.

[0027] The tractor also includes a machine frame 2 and a driving section 3. The machine frame 2 is supported by left and right front wheels 10 and left and right rear wheels 11.

[0028] The cover member 12 is disposed at the front of the vehicle body, and the driving section 3 is provided behind the cover member 12. In other words, the cover member 12 is disposed in front of the driving section 3.

[0029] The driver's section 3 has a protective frame 30, a driver's seat 31, and a steering wheel 32. An operator can sit in the driver's seat 31. This allows the operator to get into the driver's section 3. The left and right front wheels 10 are steered by operating the steering wheel 32. The operator can perform various driving operations in the driver's section 3.

[0030] The tractor is equipped with a traction battery 4. The cover member 12 is configured to be swingable about an opening / closing axis Q that extends along the left-right direction of the vehicle body. This allows the cover member 12 to be opened and closed. When the cover member 12 is in a closed state, the traction battery 4 is covered by the cover member 12.

[0031] As shown in Figures 2 and 3, the tractor includes an inverter 14 and a motor M. The traction battery 4 supplies power to the inverter 14. The inverter 14 converts DC power from the traction battery 4 into AC power (three-phase AC) and supplies it to the motor M. The motor M is then driven by the AC power supplied from the inverter 14.

[0032] 3 and 4, the tractor includes a hydrostatic continuously variable transmission 15 and a transmission 16. As shown in Fig. 4, the hydrostatic continuously variable transmission 15 has a hydraulic pump 15a and a hydraulic motor 15b.

[0033] The hydraulic pump 15a is driven by rotational power supplied from the motor M. When the hydraulic pump 15a is driven, the rotational power is output from the hydraulic motor 15b. Note that the hydrostatic continuously variable transmission 15 changes the speed of the rotational power between the hydraulic pump 15a and the hydraulic motor 15b. The hydrostatic continuously variable transmission 15 is configured to be able to change the gear ratio steplessly.

[0034] 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.

[0035] 3 and 4, 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.

[0036] If a working device is connected to the mid PTO shaft 17 or the rear PTO shaft 18, the working device will be driven by the rotational power of the mid PTO shaft 17 or the rear PTO shaft 18. For example, as shown in FIG. 3 , in this embodiment, a brush cutting device 19 is connected to the mid PTO shaft 17. The brush cutting device 19 is driven by the rotational power of the mid PTO shaft 17.

[0037] [Cooling mechanism] As described above, the inverter 14 converts the current supplied from the driving battery 4 into a three-phase AC (three-phase current) of a predetermined frequency and supplies it to the motor M. The motor M is driven in accordance with the frequency of the supplied three-phase AC.

[0038] The inverter 14 and the motor M generate heat during operation. Therefore, the inverter 14 and the motor M are cooled during operation to prevent breakdowns due to heat. The cooling mechanism of the tractor will be described below with reference to Figures 3 and 5.

[0039] In addition to the inverter 14 and the motor M, the tractor also includes a DC / DC converter 21 as a device that generates heat during operation. The DC / DC converter 21 supplies power to various accessories provided in the tractor. The DC / DC converter 21 reduces (converts) the power supplied from the driving battery 4 to a voltage suitable for each accessory and supplies the power to each accessory.

[0040] The cooling mechanism for cooling the inverter 14, the motor M, and the DC / DC converter 21, which are the objects to be cooled, includes a radiator 23, an electric pump 24, and a cooling path .

[0041] The radiator 23 cools the refrigerant that cools the inverter 14, the motor M, and the DC / DC converter 21. The radiator 23 cools the refrigerant using air circulating from the front of the aircraft. The refrigerant exchanges heat with an object to be cooled, thereby cooling the object that has generated heat.

[0042] The cooling path 26 is a path through which the refrigerant flows, traveling from the radiator 23 around the object to be cooled and returning to the radiator 23. The cooling path 26 is a hollow pipe-shaped member with an arbitrary cross-sectional shape, and the refrigerant flows through the hollow portion.

[0043] The electric pump 24 draws cooled refrigerant from the radiator 23 and circulates it through the cooling path 26. The refrigerant may be cooling water, antifreeze, cooling gas, or the like, as long as it can flow through the cooling path 26 and can properly exchange heat with the object to be cooled.

[0044] Specifically, radiator 23 is provided at the front of the aircraft, in the center of the aircraft in the left-right direction, slightly off-center to the left side. DC / DC converter 21 is provided to the right of radiator 23 and aligned with radiator 23 in the left-right direction. Because radiator 23 and DC / DC converter 21 are provided at the front of the aircraft, air can easily circulate from the front of the aircraft.

[0045] The electric pump 24 is provided behind and below the radiator 23, near the center of the vehicle body in the left-right direction.

[0046] The inverter 14 is provided near the center of the vehicle in the left-right direction behind the radiator 23. The inverter 14 is also provided below the driving battery 4 and is arranged so as to overlap the driving battery 4 in a plan view. For example, the inverter 14 is provided inside the area in which the driving battery 4 is arranged in a plan view.

[0047] The motor M is provided near the center of the vehicle in the left-right direction behind the inverter 14. The motor M is also provided below the driving battery 4 and is arranged so as to overlap the driving battery 4 in a plan view. For example, the motor M is provided inside the area where the driving battery 4 is arranged in a plan view.

[0048] The electric pump 24 sucks the refrigerant cooled by the radiator 23 out of the radiator 23 through the cooling path 26A of the cooling path 26. The electric pump 24 circulates the sucked refrigerant through the cooling path 26, circulating it through the inverter 14, the motor M, and the DC / DC converter 21 in that order, and then circulating it to the radiator 23.

[0049] The refrigerant flowing out of the electric pump 24 passes through cooling path 26B of the cooling path 26 and flows to the inverter 14. For example, cooling path 26B is provided upward, passing to the right of the electric pump 24, and is connected to a portion of the front part of the inverter 14 that is closer to the right.

[0050] The refrigerant that has circulated through the inverter 14 flows out from the left rear portion of the inverter 14 into cooling path 26C of cooling path 26. The refrigerant that has flowed out from the inverter 14 passes through cooling path 26C and is circulated to the motor M. For example, cooling path 26C is connected to inlet 28 that is provided in the upper left portion of the motor M.

[0051] The refrigerant that has circulated through the motor M flows out from a discharge port 29 provided on the upper right side of the motor M into cooling path 26D of cooling path 26. The refrigerant that has flowed out from the motor M passes through cooling path 26D and is circulated to the DC / DC converter 21. For example, cooling path 26D passes below and to the right of the inverter 14 and is connected to the DC / DC converter 21.

[0052] The refrigerant that has circulated through DC / DC converter 21 flows into cooling path 26D of cooling path 26 provided between DC / DC converter 21 and radiator 23. As a result, the refrigerant passes through cooling path 26 by electric pump 24 and flows from radiator 23 through inverter 14, motor M, and DC / DC converter 21 in that order, and is circulated to radiator 23.

[0053] With the above-described configuration, the cooling path 26 is efficiently configured according to the positions of the radiator 23, the electric pump 24, the inverter 14, the motor M, and the DC / DC converter 21.

[0054] Here, since the inverter 14 generates a three-phase AC that controls the motor M, it generally has lower heat resistance than the motor M and is more likely to become hot than the DC / DC converter 21. Therefore, the inverter 14 needs to be sufficiently cooled to prevent breakdowns due to the effects of heat, and it is preferable that the inverter 14 be cooled preferentially compared to the motor M and the DC / DC converter 21.

[0055] Furthermore, although the motor M generally has higher heat resistance than the inverter 14, the amount of heat generated by the motor M is greater than that of the inverter 14.

[0056] DC / DC converter 21 generates less heat and therefore requires less cooling than inverter 14 and motor M. In addition, DC / DC converter 21 is placed in a position where air can easily circulate, so it can be expected that it will be cooled by the air.

[0057] As described above, the refrigerant passes through the cooling path 26, flows from the radiator 23, the inverter 14, the motor M, and the DC / DC converter 21 in this order, and then circulates to the radiator 23.

[0058] In this way, the refrigerant flows through inverter 14 before motor M, which generates a large amount of heat. Here, the refrigerant cools the object to be cooled by exchanging heat with it. Therefore, the temperature of the refrigerant that has flowed through motor M, which generates a large amount of heat, rises compared to after flowing through inverter 14, and the cooling capacity of the refrigerant after flowing through motor M is significantly reduced. After being cooled by radiator 23, the refrigerant flows through inverter 14, which has a high cooling priority, before motor M, so that the refrigerant flows to inverter 14 with a sufficiently high cooling capacity, enabling inverter 14 to be cooled effectively.

[0059] Since the amount of heat generated by the inverter 14 is smaller than that of the motor M, the refrigerant maintains a sufficient cooling capacity even after flowing through the inverter 14, and can sufficiently cool the motor M.

[0060] Furthermore, the DC / DC converter 21 generates less heat than the inverter 14 and the motor M, and the cooling capacity required of the refrigerant is also small, so the refrigerant that has passed through the motor M can still cool the DC / DC converter 21 sufficiently.

[0061] As described above, the cooling mechanism according to this embodiment can efficiently cool the inverter 14, the motor M, and the DC / DC converter 21 by the refrigerant flowing through the cooling path .

[0062] [Motor] Next, the cooling configuration and arrangement of the motor M will be described with reference to FIGS. 3 and 5, and with reference to FIGS. 6 and 7. FIG.

[0063] As shown in Fig. 6, the machine body frame 2 includes a plate-shaped bottom plate 2A, a pair of left and right side plates 2B, and a vertical plate 2C. The pair of side plates 2B are plate-shaped members and are erected at both ends of the bottom plate 2A in the left-right direction (width direction) of the machine body. The vertical plate 2C is also a plate-shaped member and is disposed so as to be perpendicular to the bottom plate 2A and the pair of side plates 2B.

[0064] The motor M is disposed above the bottom plate 2A and is cantilevered on the front surface of the vertical plate 2C. The motor M comprises a main body 34 and a plate-shaped mounting plate 35 provided at the rear of the main body 34. The mounting plate 35 of the motor M is supported on the front surface of the vertical plate 2C. The main body 34 of the motor M is disposed between the pair of side plates 2B. A hydraulic pump 6 is supported on the front surface of the vertical plate 2C, side by side with the motor M, with one of the side plates 2B in between. The hydraulic pump 6 is driven by the motor M and supplies hydraulic oil to the hydraulic equipment.

[0065] The motor M is provided with a three-phase power supply terminal 37, to which a three-phase alternating current (three-phase current) is input, on the front surface of the motor M. The motor M also is provided with a signal terminal 38, to which various signals are input and output, on the front surface of the motor M.

[0066] The motor M has a stator (not shown) and a rotor (not shown) provided inside the main body 34. The stator is provided along the inside of the peripheral side surface 39 of the main body 34 so as to surround the rotor. When three-phase alternating current is input to the stator of the motor M, the rotor rotates about the rotation axis P. As the rotor rotates, driving force is transmitted to the hydrostatic continuously variable transmission 15.

[0067] As shown in Fig. 7, the motor M has a spiral motor coolant flow path 40 that runs along the peripheral side surface 39 of the main body portion 34. The peripheral side surface 39 has a double structure, and the motor coolant flow path 40 is formed between an inner peripheral side surface 39A on the inside and an outer peripheral side surface 39B on the outside (partially omitted in Fig. 7 to illustrate the internal structure).

[0068] A recess is formed in the peripheral side surface 39 of the motor M, and the inner peripheral side surface 39A corresponds to the bottom surface of the recess. The area surrounded by the front end surface 41 of the recess, the rear end surface 42 of the recess, the inner peripheral side surface 39A, and the outer peripheral side surface 39B forms the motor refrigerant flow path 40.

[0069] A partition wall 44 is provided inside the motor refrigerant channel 40. The partition wall 44 extends from a position contacting the front end face 41 to a position contacting the rear end face 42, at an angle relative to the circumferential direction of the circumferential side face 39. The length of the partition wall 44 in the circumferential direction of the circumferential side face 39 is approximately one-quarter of the circumferential length (circumferential length) of the circumferential side face 39. The partition wall 44 is provided along the inner circumferential side face 39A and the outer circumferential side face 39B and contacts the inner circumferential side face 39A and the outer circumferential side face 39B. As a result, the motor refrigerant channel 40 has a spiral shape extending from a starting end 44a of the partition wall 44 that contacts the front end face 41 to a terminal end 44b that contacts the rear end face 42. The length of the motor refrigerant channel 40 is approximately the sum of the circumferential length of the circumferential side face 39 and the length of the partition wall 44.

[0070] With this configuration, the length of the motor coolant flow path 40 can be efficiently increased on the peripheral side surface 39 of the motor M, and the motor M can be efficiently cooled.

[0071] The motor refrigerant flow path 40 includes an inlet section 28 that serves as an entrance through which the refrigerant flowing through the cooling path 26 enters the motor refrigerant flow path 40, and an outlet section 29 that serves as an exit through which the refrigerant that has flowed through the motor refrigerant flow path 40 is discharged into the cooling path 26.

[0072] Inlet portion 28 extends from motor coolant flow path 40 through outer circumferential side surface 39B and is located in an area adjacent to the outlet portion 29 side of starting end 44a of partition wall 44. Outlet portion 29 extends from motor coolant flow path 40 through outer circumferential side surface 39B and is located in an area adjacent to the inlet portion 28 side of terminal end 44b of partition wall 44. As a result, the coolant flows in from inlet portion 28, flows spirally through motor coolant flow path 40 along circumferential side surface 39, and is discharged from outlet portion 29 into cooling path 26.

[0073] As shown in FIG. 6 , in a front view, the inlet section 28 and the outlet section 29 are located above a horizontal center line LCL. The horizontal center line LCL is an imaginary line that passes through the rotation axis P, which is the center point of the motor M (main body portion 34), and extends in the left-right direction (width direction) of the machine body. Furthermore, the inlet section 28 and the outlet section 29 are preferably located above the upper end of the side plate 2B. Furthermore, the inlet section 28 and the outlet section 29 are located on the left and right sides (width direction) of the vertical center line VCL. The vertical center line VCL is an imaginary line that passes through the rotation axis P, which is the center point of the motor M (main body portion 34), and extends in the up-down direction (height direction) of the machine body. For example, in a front view, the inlet section 28 is located in a left region of the motor M, and the outlet section 29 is located in a right region of the motor M.

[0074] In particular, it is preferable that the interior angle θ1 formed by the line segment connecting the center of the inlet of the inflow section 28 to the rotation axis P and the horizontal center line LCL is 30° or more and 55° or less. Also, it is preferable that the interior angle θ2 formed by the line segment connecting the center of the outlet of the discharge section 29 to the rotation axis P and the horizontal center line LCL is 30° or more and 55° or less.

[0075] By arranging the inlet section 28 and the outlet section 29 in this manner, the inlet section 28 and the outlet section 29 can efficiently connect the motor refrigerant flow path 40 and the cooling path 26, and the inlet section 28 and the outlet section 29 in the motor M are efficiently arranged.

[0076] Furthermore, in a front view, the inlet section 28 is preferably provided in an area surrounded by a horizontal center line LCL, a vertical center line VCL, and a vertical left edge line VLL (first vertical line). The vertical left edge line VLL is an imaginary line that passes through the left end of the motor M and extends in the up-down direction (height direction) of the machine body. Similarly, in a front view, the outlet section 29 is preferably provided in an area surrounded by the horizontal center line LCL, the vertical center line VCL, and a vertical right edge line VRL (second vertical line). The vertical right edge line VRL is an imaginary line that passes through the right end of the motor M and extends in the up-down direction (height direction) of the machine body.

[0077] As a result, in a front view, the inlet portion 28 and the outlet portion 29 are disposed inside the top, bottom, left, and right ends of the motor M (main body portion 34 and mounting plate 35). Therefore, the motor M including the inlet portion 28 and the outlet portion 29 is disposed efficiently inside the machine body.

[0078] In addition, the three-phase power supply terminals 37 are provided below the horizontal center line LCL in a front view. Similarly, the signal terminals 38 are provided near the horizontal center line LCL in the up-down direction.

[0079] As a result, the three-phase power supply terminals 37 and signal terminals 38 are disposed above and below the motor M, away from the inlet portion 28 and the outlet portion 29. Therefore, even if the refrigerant leaks from the inlet portion 28 or the outlet portion 29, the refrigerant is prevented from adhering to the three-phase power supply terminals 37 and the signal terminals 38. As a result, problems with the three-phase power supply terminals 37 and the signal terminals 38 caused by the refrigerant are prevented.

[0080] Furthermore, it is preferable that the three-phase power supply terminal 37 is disposed in the center in the left-right direction (width direction) of the machine body, and the signal terminal 38 is disposed to the left or right of the vertical center line VCL, that is, eccentric in the left-right direction (width direction) of the machine body with respect to the three-phase power supply terminal 37. For example, the signal terminal 38 is provided near the right end of the main body 34 of the motor M.

[0081] A high-frequency, high-voltage three-phase AC current is input to the three-phase power supply terminal 37, and a stable frequency and voltage must be input to control the rotation speed of the motor M. In addition, various control signals and detection signals are input and output to and from the signal terminal 38.

[0082] Therefore, by arranging the three-phase power supply terminals 37 and the signal terminals 38 at positions spaced apart in the vertical direction (height direction) and horizontal direction (width direction) of the body of the machine, the three-phase power supply terminals 37 and the signal terminals 38 are prevented from being affected by noise from each other, allowing the motor M to operate with precision.

[0083] The case portion of the motor M, including the motor coolant flow path 40, is manufactured by casting. The motor coolant flow path 40 is molded using a core made of sand. Therefore, the motor coolant flow path 40 of the main body portion 34 is provided with an outlet 46 for discharging the sand from the core. A plurality of outlets 46 are provided along the motor coolant flow path 40. A lid is eventually formed over the outlet 46.

[0084] [Inverter] Next, a configuration including a cooling configuration for the inverter 14 will be described using FIGS. 8 to 11 while also referring to FIGS. 3 and 5. FIG.

[0085] The inverter 14 converts the DC current supplied from the driving battery 4 into a three-phase AC current (three-phase current / three-phase power supply) of a predetermined frequency and supplies it to the motor M.

[0086] As shown in FIG. 8, the inverter 14 includes an inverter case 50 and components provided inside the inverter case 50, such as a capacitor 51, an IGBT 52 which is an example of a power transistor, and a resistor 53.

[0087] Capacitor 51 smoothes the DC current supplied from driving battery 4. IGBT 52 converts the DC current smoothed by capacitor 51 into three-phase AC of a predetermined frequency and supplies it to motor M. Resistor 53 is a power consumption resistor provided to discharge the current charged in capacitor 51 after inverter 14 is stopped.

[0088] The inverter case 50 is composed of outer plates including a mounting plate 50A, and an enclosed space surrounded by the outer plates is formed inside the inverter case 50. The capacitor 51, the IGBT 52, and the resistor 53 are supported by the mounting plate 50A within the enclosed space.

[0089] The capacitor 51, the IGBT 52, and the resistor 53 generate heat during operation and may fail due to the heat. Therefore, the inverter 14 includes an inverter coolant flow path 55 that cools the components to be cooled, such as the capacitor 51, the IGBT 52, and the resistor 53.

[0090] Inverter refrigerant flow path 55 is provided inside mounting plate 50A, and is a flow path through which the refrigerant introduced from cooling path 26 flows. Inverter case 50 has inlet section 56 and outlet section 57, and the refrigerant flowing through cooling path 26 (cooling path 26B) flows from inlet section 56 into inverter refrigerant flow path 55, and the refrigerant that has flowed through inverter refrigerant flow path 55 flows from outlet section 57 to cooling path 26 (cooling path 26C).

[0091] Inverter coolant flow path 55 is formed within mounting plate 50A along the components to be cooled so as to cool the components of inverter 14. In the example of Fig. 8, capacitor 51, IGBT 52, and resistor 53 are held on the upper surface of mounting plate 50A, and therefore inverter coolant flow path 55 is formed below capacitor 51, IGBT 52, and resistor 53 within mounting plate 50A.

[0092] For example, inverter refrigerant flow path 55 is a path that runs from inlet 56 through a region along capacitor 51 , a region along IGBT 52 , and a region along resistor 53 .

[0093] Generally, the capacitor 51 generates less heat than the IGBT 52, but has lower heat resistance than the IGBT 52 and the resistor 53. Therefore, the capacitor 51 is the component in the inverter 14 that needs to be cooled with the highest priority.

[0094] Similarly, the IGBT 52 generates a high-voltage AC current (three-phase AC) and therefore generates more heat than the capacitor 51 and the resistor 53, but has a higher heat resistance temperature than the capacitor 51, so the capacitor 51 is more likely to fail first. Also, the resistor 53 is less likely to fail than the capacitor 51 and the IGBT 52, so there is less need to cool it.

[0095] As described above, since the refrigerant cools the capacitor 51, the IGBT 52, and the resistor 53 in this order, the capacitor 51 is preferentially cooled, and the capacitor 51 is efficiently cooled. If the capacitor 51 is cooled after the IGBT 52, the refrigerant after cooling the IGBT 52 will rise significantly in temperature, making it difficult to sufficiently cool the capacitor 51. Conversely, even if it is the refrigerant that has been heated up after cooling the capacitor 51, the IGBT 52 has a large amount of heat generation and becomes hotter than the refrigerant. Also, since the IGBT 52 has stronger heat resistance than the capacitor 51, the IGBT 52 can be sufficiently cooled. Further, the resistor 53 has less need for cooling compared to the capacitor 51 and the IGBT 52.

[0096] From the above, by forming the inverter refrigerant flow path 55 so that cooling is performed in the order of the capacitor 51, the IGBT 52, and the resistor 53, the capacitor 51, the IGBT 52, and the resistor 53 can be efficiently cooled according to their characteristics.

[0097] For example, the inverter refrigerant flow path 55 goes from the inflow portion 56 along the capacitor 51 toward the rear of the machine body, makes a U-turn near the rear end portion of the capacitor 51, and goes toward the front of the machine body along the capacitor 51. Further, the inverter refrigerant flow path 55 makes a U-turn again in front of the IGBT 52 and goes toward the rear of the machine body along the IGBT 52 while widening the width of the flow path (the width in the left-right direction of the machine body). Then, the inverter refrigerant flow path 55 goes toward the rear of the machine body so as to reach the discharge portion 57 via the resistor 53 while narrowing the width of the flow path.

[0098] With such a configuration, the refrigerant flowing through the inverter refrigerant flow path 55 can efficiently cool the capacitor 51, the IGBT 52, and the resistor 53.

[0099] <Cooling Structure of IGBT><M As shown in FIG. 9, the IGBT 52 includes a heat sink. The heat sink may be fins or the like, or may be pin fins 52A provided in a matrix on one surface of the IGBT 52.

[0100] A through-hole 50B is provided in the mounting plate 50A in an area where the IGBT 52 is disposed. The through-hole 50B passes from the sealed space of the inverter case 50 to the inverter refrigerant flow path 55. The IGBT 52 is supported on the mounting plate 50A such that the pin fins 52A are disposed within the through-hole 50B. The pin fins 52A extend through the through-hole 50B to reach the inverter refrigerant flow path 55.

[0101] As a result, the pin fins 52A are in direct contact with the refrigerant flowing through the inverter refrigerant flow path 55, and the IGBTs 52 can be efficiently cooled via the pin fins 52A.

[0102] Furthermore, it is preferable that the inner diameter of inverter refrigerant flow path 55 be narrower at the position where pin fins 52A protrude from inverter refrigerant flow path 55. For example, at the position where pin fins 52A protrude from inverter refrigerant flow path 55, mounting plate 50A at a position opposite pin fins 52A has protrusion 50C protruding toward the inside of inverter refrigerant flow path 55.

[0103] The inner diameter of inverter refrigerant flow path 55 is narrowed at the positions where pin fins 52A of inverter refrigerant flow path 55 protrude, thereby increasing the flow rate of the refrigerant flowing through this portion and enabling the refrigerant to efficiently cool IGBT 52 via pin fins 52A. In addition, the refrigerant comes into contact with pin fins 52A with precision, enabling the refrigerant to accurately cool IGBT 52 via pin fins 52A.

[0104] 9 and 10, the inverter 14 preferably includes an O-ring 52B that seals the gap between the IGBT 52 and the mounting plate 50A in the through-hole 50B. For example, the O-ring 52B is provided so as to be in close contact with the outer periphery of the IGBT 52 and the inner periphery of the through-hole 50B.

[0105] This prevents the refrigerant flowing through inverter refrigerant flow path 55 from flowing through through-hole 50B into the sealed space of inverter 14. As a result, malfunctions of various components of inverter 14 caused by the refrigerant are prevented.

[0106] <Capacitor cooling structure> 11, capacitor 51 is supported on the surface of mounting plate 50A within the sealed space. At least the area of ​​the bottom surface of capacitor 51 near the inverter refrigerant flow path 55 is formed smooth and flush. At least the area of ​​mounting plate 50A near the area where capacitor 51 is mounted is formed smooth and flush. Therefore, at least the area of ​​capacitor 51 near the area along inverter refrigerant flow path 55 is in surface contact with mounting plate 50A and is in tight contact with it.

[0107] By bringing the capacitor 51 and the mounting plate 50A into close contact with each other, the refrigerant flowing through the inverter refrigerant flow path 55 can efficiently exchange heat with the condenser 51 through the mounting plate 50A, thereby efficiently cooling the condenser 51.

[0108] Further, refrigerant reservoir 55A is provided near inlet 56 of inverter refrigerant flow path 55. For example, refrigerant reservoir 55A is provided in inverter refrigerant flow path 55, extending from inlet 56 to an end region on the inlet 56 side of a region along condenser 51.

[0109] Refrigerant reservoir 55A is configured to be able to store refrigerant, with a refrigerant flow diameter, which is the vertical cross-sectional area of ​​the refrigerant flow path, larger than the flow diameters of the other inverter refrigerant flow paths 55. This allows refrigerant to be stored in inverter refrigerant flow path 55 and a sufficient amount of refrigerant to be supplied to inverter refrigerant flow path 55, thereby efficiently cooling the components to be cooled that are mounted on inverter 14.

[0110] <Other structures> 8, the inverter 14 includes a water temperature sensor 59 (temperature sensor) that measures the temperature of the refrigerant flowing through the inverter refrigerant flow path 55, for example, the temperature of the cooling water serving as the refrigerant. The water temperature sensor 59 is provided, for example, in the inverter refrigerant flow path 55, between the cooling region of the capacitor 51 and the cooling region of the IGBT 52. More specifically, the water temperature sensor 59 is provided in a U-turn portion of the inverter refrigerant flow path 55 in the cooling region of the capacitor 51, or the like.

[0111] The capacitor 51 is highly in need of cooling, and if the temperature of the refrigerant that has cooled the capacitor 51 or is cooling the capacitor 51 reaches or exceeds a predetermined temperature, it can be determined that the capacitor 51 is not sufficiently cooled. Also, if the temperature of the refrigerant that cools the IGBT 52 reaches or exceeds another predetermined temperature, it can be determined that the IGBT 52 cannot be sufficiently cooled. Also, the operating status of the inverter 14 can be confirmed based on the measured water temperature (temperature of the refrigerant).

[0112] Therefore, the temperature of the cooling water (refrigerant) is measured by the water temperature sensor 59, and the flow rate of the refrigerant flowing through the inverter refrigerant flow path 55 and the operation of the inverter 14 can be controlled according to the water temperature. For example, if the water temperature (refrigerant temperature) measured by the water temperature sensor 59 is equal to or higher than a predetermined temperature, the electric pump 24 can be controlled to increase the refrigerant flow rate or the inverter 14 can be stopped. Also, if the water temperature (refrigerant temperature) measured by the water temperature sensor 59 is approximately room temperature, it can be determined that the inverter 14 is not operating, and control can be performed to stop the flow of refrigerant at least through the inverter 14 (inverter refrigerant flow path 55). This allows the inverter 14 to be cooled efficiently and accurately.

[0113] The inverter 14 also includes a current sensor 58 that measures the current value of the three-phase AC generated by the IGBT 52. The current sensor 58 is supported on the three-phase AC wiring 52C in front of the IGBT 52. The IGBT 52 generates a predetermined three-phase AC while referring to the current value measured by the current sensor 58.

[0114] The current sensor 58 may be disposed so as to have an area overlapping with the inverter refrigerant flow path 55 in a plan view, or may be disposed apart from the inverter refrigerant flow path 55. The current sensor 58 generates less heat than the IGBT 52 and has lower heat resistance than the capacitor 51. Therefore, the current sensor 58 does not necessarily need to be disposed along the inverter refrigerant flow path 55, and is sufficiently cooled by exchanging heat with the refrigerant through the inverter case 50.

[0115] [Another embodiment] (1) The thermal resistance of the inverter 14 is not always low. Similarly, the amount of heat generated by the motor M is not always high. Therefore, in the above embodiment, the cooling path 26 is not limited to a configuration in which the refrigerant flows through the inverter 14, motor M, and DC / DC converter 21 in this order, but the refrigerant may flow through the inverter 14, motor M, and DC / DC converter 21 in any order depending on the amount of heat generated and the thermal resistance of the inverter 14, motor M, and DC / DC converter 21.

[0116] This allows for an efficient cooling mechanism to be configured in accordance with the characteristics of the object to be cooled.

[0117] (2) In each of the above embodiments, the cooling mechanism (cooling path 26) may be configured to cool at least one of the inverter 14, the motor M, and the DC / DC converter 21. For example, the cooling path 26 may be configured not to pass through the DC / DC converter 21. In this case, the cooling path 26 serves as a path that returns the refrigerant that flows out of the motor M directly to the radiator 23 without circulating it through the DC / DC converter 21.

[0118] Conversely, the cooling mechanism (cooling path 26) may be configured to cool at least one of the inverter 14, the motor M, and the DC / DC converter 21, as well as other cooling targets.

[0119] As described above, the cooling mechanism (cooling path 26) can be configured with a high degree of freedom, and the cooling mechanism can cool various cooling targets. For example, a battery or a charger can be placed along the cooling path 26, and the battery or charger can be cooled by the cooling mechanism.

[0120] (3) In each of the above embodiments, the arrangement of the radiator 23, cooling path 26, electric pump 24, inverter 14, motor M, and DC / DC converter 21 is not limited to the above configuration and may be arbitrary. By optimizing the arrangement of these components according to the characteristics and operating conditions of the object to be cooled, the object to be cooled can be cooled efficiently.

[0121] (4) In each of the above embodiments, the motor refrigerant flow path 40 may be a spiral flow path that winds any number of times around the circumferential surface 39. The length of the motor refrigerant flow path 40, which is proportional to the number of windings of the spiral, is determined by the number of times the partition wall 44 winds around the circumferential surface 39 along the circumferential surface 39.

[0122] This makes it possible to easily configure the motor coolant flow path 40 with an appropriate length depending on the characteristics of the motor M, and to efficiently cool the motor M.

[0123] (5) In each of the above embodiments, the three-phase power supply terminals 37 and the signal terminals 38 may be disposed at any position. This allows the structure of the motor M to be optimized with a high degree of freedom.

[0124] (6) In each of the above embodiments, the inverter 14 may be equipped with other components to be cooled in addition to the capacitor 51, the IGBT 52, the resistor 53, and the current sensor 58. Conversely, the inverter 14 may not be equipped with any of the capacitor 51, the IGBT 52, the resistor 53, and the current sensor 58.

[0125] This allows the components that require cooling to be efficiently cooled within the required range according to the required configuration of inverter 14.

[0126] (7) In each of the above embodiments, the electric work vehicle may employ any traveling device, such as crawlers, instead of the front wheels 10 and rear wheels 11.

[0127] (8) In each of the above embodiments, the present invention is not limited to electric tractors, but can also be applied to electric agricultural vehicles such as electric combine harvesters and electric rice transplanters, and electric work vehicles that perform various types of work. [Industrial Applicability]

[0128] The present invention can be applied to electric work vehicles that perform various types of work, such as agricultural work. [Explanation of symbols]

[0129] 10 Front wheels (running gear) 11 Rear wheels (running gear) 14 Inverter 23 Radiator 26 Cooling Path 50 Inverter case 50A mounting board 50B through hole 50C protrusion 51 Capacitor 52 IGBT (power transistor) 52A Pin Fin (Heat Sink) 52B O-ring 53 Resistance 55 Inverter refrigerant flow path 55A Refrigerant reservoir 59 Water temperature sensor (temperature sensor) Medium motor

Claims

1. The aircraft and a running device provided on the aircraft body; a motor that drives the traveling device; an inverter that supplies power to the motor; a radiator that cools the refrigerant; a cooling path through which the refrigerant cooled by the radiator circulates around at least the inverter and back to the radiator; The inverter is an inverter case including a mounting plate and forming an enclosed space; a capacitor held on the mounting plate within the sealed space and smoothing the input direct current; a power transistor held by the mounting plate within the sealed space and configured to convert a direct current supplied from the capacitor into a three-phase alternating current of a predetermined frequency; a resistor held by the mounting plate within the sealed space and configured to discharge power from the inverter; an inverter coolant flow path provided inside the mounting plate, through which the coolant circulates inside the inverter to cool the capacitor, the power transistor, and the resistor; the power transistor has a heat sink; the inverter refrigerant flow path has a through hole that penetrates toward the sealed space, the heat sink passes through the through hole and protrudes into the inverter refrigerant flow path; the inverter refrigerant flow path includes a protrusion where the mounting plate protrudes toward the power transistor in a region overlapping with the position of the power transistor in the inverter refrigerant flow path.

2. The aircraft and a running device provided on the aircraft body; a motor that drives the traveling device; an inverter that supplies power to the motor; a radiator that cools the refrigerant; a cooling path through which the refrigerant cooled by the radiator circulates around at least the inverter and back to the radiator; The inverter is an inverter case including a mounting plate and forming an enclosed space; a capacitor held on the mounting plate within the sealed space and smoothing the input direct current; a power transistor held by the mounting plate within the sealed space and configured to convert a direct current supplied from the capacitor into a three-phase alternating current of a predetermined frequency; a resistor held by the mounting plate within the sealed space and configured to discharge power from the inverter; an inverter coolant flow path provided inside the mounting plate, through which the coolant circulates inside the inverter to cool the capacitor, the power transistor, and the resistor; the power transistor has a heat sink; the inverter refrigerant flow path has a through hole that penetrates toward the sealed space, the heat sink passes through the through hole and protrudes into the inverter refrigerant flow path; The inverter refrigerant flow path has a refrigerant reservoir in an inflow area of ​​the refrigerant, and the cross-sectional area of ​​the refrigerant reservoir is larger than the cross-sectional area of ​​the other inverter refrigerant flow paths.

3. The aircraft and a running device provided on the aircraft body; a motor that drives the traveling device; an inverter that supplies power to the motor; a radiator that cools the refrigerant; a cooling path through which the refrigerant cooled by the radiator circulates around at least the inverter and back to the radiator; The inverter is an inverter case including a mounting plate and forming an enclosed space; a capacitor held on the mounting plate within the sealed space and smoothing the input direct current; a power transistor held by the mounting plate within the sealed space and configured to convert a direct current supplied from the capacitor into a three-phase alternating current of a predetermined frequency; a resistor held by the mounting plate within the sealed space and configured to discharge power from the inverter; an inverter coolant flow path provided inside the mounting plate, through which the coolant circulates inside the inverter to cool the capacitor, the power transistor, and the resistor; the power transistor has a heat sink; the inverter refrigerant flow path has a through hole that penetrates toward the sealed space, the heat sink passes through the through hole and protrudes into the inverter refrigerant flow path; The refrigerant cools the capacitor, the power transistor, and the resistor in this order.

4. 4. The electric work vehicle according to claim 3, further comprising a temperature sensor for measuring the temperature of the refrigerant in the inverter refrigerant flow path between a position for cooling the capacitor and a position for cooling the power transistor.

5. The electric work vehicle according to claim 1 , wherein the inverter includes an O-ring that seals a gap between an outer periphery of the power transistor and an inner periphery of the through hole.

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