JP7565909B2 - Electric work vehicle - Google Patents

Description

The present invention relates to an electric work vehicle whose running gear is driven by a motor.

As shown in Patent Document 1, an electric work vehicle (electric work machine) drives a traveling device by a motor (electric motor). The electric work vehicle is equipped with a traveling battery, an inverter, etc. to drive the motor, and further equipped with a DC/DC converter to convert the voltage of the power supplied to various auxiliary machines.

The electric work vehicle also has a radiator and a cooling path to cool the motor, inverter, DC/DC converter, etc. The cooling path is a path through which the refrigerant cooled by the radiator is circulated to the radiator around the motor, inverter, DC/DC converter, etc.

JP 2021-80709 A

However, there is a demand for more efficient cooling of objects such as motors, inverters, and DC/DC converters, and for stabilizing the performance of the objects.

The present invention aims to efficiently cool the object to be cooled.

In order to achieve the above-mentioned object, an electric work vehicle according to one embodiment of the present invention comprises a body, a traveling device provided on the body, a motor that drives the traveling device, an inverter that supplies power to the motor, electrical components, a DC/DC converter that converts the voltage of the power supplied to the electrical components, a radiator that cools a refrigerant, and a cooling path in which the refrigerant cooled in the radiator circulates around the motor, the inverter, and the DC/DC converter to the radiator, wherein the cooling path passes from the radiator through the inverter, the motor, and the DC/DC converter in that order , and returns to the radiator, and in a plan view, the portion of the cooling path that extends from the motor to the DC/DC converter does not overlap with the inverter, and in a side view, the portion of the cooling path that extends from the motor to the DC/DC converter does not overlap with the inverter .

Instruments such as inverters, motors, and DC/DC converters generate heat during operation. Furthermore, these devices can malfunction due to the effects of heat. For this reason, the devices are cooled during operation.

Here, motors generate a large amount of heat while in operation. In addition, inverters generate less heat than motors, but generally have lower heat resistance than motors and are more susceptible to heat. DC/DC converters also generate less heat and are less likely to break down due to heat than motors and inverters.

As a result, the refrigerant flowing through the cooling path of the electric work vehicle cools the inverter, motor, and DC/DC converter in that order.

This allows the inverter, which has low heat resistance and should be cooled first, to be cooled first.

In addition, because the motor generates a large amount of heat, the temperature of the refrigerant increases significantly after exchanging heat with the motor to cool it, and the cooling performance of the refrigerant decreases. The refrigerant cools the inverter before the motor, so the inverter is properly cooled. Note that the inverter generates less heat than the motor, which generates a large amount of heat, so the refrigerant after cooling the inverter can properly cool the motor. Furthermore, the DC/DC converter generates a small amount of heat and requires less cooling than the inverter. Therefore, the refrigerant after cooling the motor can adequately cool the DC/DC converter.

As a result, the refrigerant flowing through the cooling path can efficiently and appropriately cool the inverter, motor, and DC/DC converter.

Also, the forward movement of the aircraft may be defined as the front, and the radiator, inverter, and motor may be arranged in the fore-and-aft direction of the aircraft, in that order from front to back.

With this configuration, the radiator, inverter, and motor are arranged in the order that the refrigerant cools them, allowing for an efficient cooling path and efficient cooling of the inverter, motor, and DC/DC converter.

The DC/DC converter may also be disposed laterally on one side of the radiator in a left-right direction perpendicular to the front-rear direction.

The cooling path is provided from the DC/DC converter to the radiator. As described above, the DC/DC converter and the radiator are provided side-by-side, so that an efficient cooling path is provided from the DC/DC converter to the radiator.

In addition, a portion of the cooling path that runs from the inverter to the motor may be connected to the motor on the other side of the motor in the left-right direction, and a portion of the cooling path that runs from the motor to the DC/DC converter may be connected to the motor on the one side of the motor.

With this configuration, the cooling path from the motor to the DC/DC converter is provided on the side where the DC/DC converter is located in the left-right direction. In addition, the cooling path from the inverter to the motor and the cooling path from the motor to the DC/DC converter are distributed and located on both the left and right sides of the motor.

As a result, the cooling path from the inverter to the motor and the cooling path from the motor to the DC/DC converter are efficiently configured.

The vehicle may further include a driving battery that stores the power supplied to the motor via the inverter, and the inverter may be disposed below the driving battery so that the inverter overlaps with the driving battery in a plan view.

This configuration allows the inverter and the drive battery to be positioned efficiently.

FIG. FIG. FIG. 4 is a left side view illustrating an example of the arrangement of an inverter and the like. FIG. FIG. 2 is a plan view illustrating a schematic configuration of a cooling path. FIG. 2 is a front view illustrating an example of a main part of a motor arrangement configuration. FIG. 2 is a perspective view illustrating a schematic configuration of a motor coolant flow path. FIG. 2 is a plan view illustrating a configuration of a main part of an inverter; 9 is a cross-sectional left side view showing a main part of the cross section taken along line IX-IX in FIG. 8 . FIG. 2 is a bottom view illustrating the configuration of an IGBT. 10 is a cross-sectional left side view showing a main portion of the cross section taken along the line XI-XI in FIG. 8.

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 drawings is "forward", the direction of the arrow B is "backward", the direction of the arrow U is "up", the direction of the arrow D is "down", the direction of the arrow L is "left", and the direction of the arrow R is "right".

[Overall configuration of the tractor]
In the following, an electric tractor (hereinafter, simply referred to as a tractor) will be described 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.

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.

The cover member 12 is disposed at the front of the aircraft. 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.

The driver's unit 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 board the driver's unit 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 unit 3.

The tractor is equipped with a driving battery 4. The cover member 12 is configured to be swingable around 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 driving battery 4 is covered by the cover member 12.

As shown in Figures 2 and 3, the tractor includes an inverter 14 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 (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.

As shown in Figures 3 and 4, the tractor is equipped with a hydrostatic continuously variable transmission 15 and a transmission 16. As shown in Figure 4, the hydrostatic continuously variable transmission 15 has a hydraulic pump 15a and a hydraulic motor 15b.

The hydraulic pump 15a is driven by the rotational power supplied 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 changes the speed of the rotational power between the hydraulic pump 15a and the hydraulic motor 15b. The hydrostatic continuously variable transmission 15 is also configured to be able to change the gear ratio steplessly.

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. This drives the left and right front wheels 10 and the left and right rear wheels 11.

As shown in Figures 3 and 4, the tractor also includes 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.

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. 3, 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.

[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.

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

Here, in addition to the inverter 14 and the motor M, the tractor is equipped with a DC/DC converter 21 as a device that generates heat during operation. The DC/DC converter 21 supplies power to various auxiliary devices equipped in the tractor. The DC/DC converter 21 steps down (converts) the power supplied from the driving battery 4 to a voltage corresponding to each auxiliary device and supplies it to each auxiliary device.

The cooling mechanism for cooling the inverter 14, motor M, and DC/DC converter 21, which are the objects to be cooled, includes a radiator 23, an electric pump 24, and a cooling path 26.

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 the object to be cooled, thereby cooling the object that has generated heat.

The cooling path 26 is a path through which the refrigerant flows, from the radiator 23 around the object to be cooled, and back to the radiator 23. The cooling path 26 is a hollow pipe-shaped component with an arbitrary cross-sectional shape, and the refrigerant flows through the hollow part.

The electric pump 24 draws the cooled refrigerant from the radiator 23 and circulates it through the cooling path 26. The refrigerant may be any type of refrigerant that can flow through the cooling path 26 and can properly exchange heat with the object to be cooled, such as cooling water, antifreeze, or cooling gas.

Specifically, the radiator 23 is mounted in the front of the aircraft, in the center of the aircraft in the left-right direction, slightly off-center to the left side. The DC/DC converter 21 is mounted to the right of the radiator 23, side-by-side with the radiator 23 in the left-right direction. Because the radiator 23 and the DC/DC converter 21 are mounted in the front of the aircraft, air can easily circulate from the front of the aircraft.

The electric pump 24 is located behind and below the radiator 23, near the center of the aircraft in the left-right direction.

The inverter 14 is provided near the center of the vehicle body in the left-right direction, rearward of 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 arrangement area of the driving battery 4 in a plan view.

The motor M is provided near the center of the vehicle body in the left-right direction, rearward of 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 planar view. For example, the motor M is provided inside the area in which the driving battery 4 is arranged in a planar view.

The electric pump 24 draws 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 drawn 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.

The refrigerant flowing out of the electric pump 24 is circulated to the inverter 14 through the cooling path 26B of the cooling path 26. For example, the cooling path 26B is provided upward through the right side of the electric pump 24 and is connected to the right-hand part of the front part of the inverter 14.

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

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

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

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

The inverter 14 generates three-phase AC to control the motor M, and therefore generally has lower heat resistance than the motor M, and is more susceptible to overheating than the DC/DC converter 21. Therefore, the inverter 14 needs to be sufficiently cooled to prevent breakdowns caused by heat, and it is preferable to give cooling priority over the motor M and the DC/DC converter 21.

Motor M generally has higher heat resistance than inverter 14, but generates more heat than inverter 14.

The DC/DC converter 21 generates less heat than the inverter 14 and the motor M, and so has little need for cooling. In addition, the 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.

Then, as described above, the refrigerant passes through the cooling path 26, flows from the radiator 23, through the inverter 14, the motor M, and the DC/DC converter 21, and then circulates to the radiator 23.

In this way, the refrigerant flows through the inverter 14 before the 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 flows through the motor M, which generates a large amount of heat, rises compared to after it has flowed through the inverter 14, and the cooling capacity of the refrigerant after it has flowed through the motor M is significantly reduced. After being cooled by the radiator 23, the refrigerant flows through the inverter 14, which has a high cooling priority, before the motor M, so that the refrigerant flows through the inverter 14 with a sufficiently high cooling capacity and can effectively cool the inverter 14.

In addition, since the amount of heat generated by the inverter 14 is smaller than that of the motor M, the refrigerant retains sufficient cooling capacity even after flowing through the inverter 14, and is therefore able to adequately cool the motor M.

In addition, 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.

As a result, the cooling mechanism according to this embodiment can efficiently cool the inverter 14, the motor M, and the DC/DC converter 21 using the refrigerant flowing through the cooling path 26.

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

As shown in FIG. 6, the aircraft frame 2 comprises 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 on both ends of the bottom plate 2A in the left-right direction (width direction) of the aircraft. The vertical plate 2C is a plate-shaped member and is arranged so as to be perpendicular to the bottom plate 2A and the pair of side plates 2B.

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

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

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 AC is input to the stator, the motor M rotates the rotor about the rotation axis P. As the rotor rotates, the driving force is transmitted to the hydrostatic continuously variable transmission 15.

As shown in FIG. 7, the motor M has a spiral motor coolant flow passage 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 passage 40 is formed between the inner peripheral side surface 39A on the inside and the outer peripheral side surface 39B on the outside (partially omitted in FIG. 7 to show the internal structure).

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 coolant flow path 40.

A partition wall 44 is provided inside the motor refrigerant flow path 40. The partition wall 44 is provided from a position in contact with the front end face 41 to a position in contact with the rear end face 42, obliquely with respect 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 about 1/4 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 is in contact with the inner circumferential side face 39A and the outer circumferential side face 39B. As a result, the motor refrigerant flow path 40 has a spiral shape from the start end 44a of the partition wall 44 that is in contact with the front end face 41 to the end end 44b that is in contact with the rear end face 42. The length of the motor refrigerant flow path 40 is approximately the circumferential length of the circumferential side face 39 plus the length of the partition wall 44.

With this configuration, the length of the motor coolant flow path 40 can be efficiently increased on the peripheral surface 39 of the motor M, allowing the motor M to be efficiently cooled.

The motor refrigerant flow path 40 includes an inlet section 28 that serves as an inlet 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 outlet through which the refrigerant that has flowed through the motor refrigerant flow path 40 is discharged into the cooling path 26.

The inlet 28 penetrates the outer peripheral side surface 39B from the motor refrigerant flow path 40 and is provided in an area adjacent to the outlet 29 side of the starting end 44a of the partition 44. The outlet 29 penetrates the outer peripheral side surface 39B from the motor refrigerant flow path 40 and is provided in an area adjacent to the inlet 28 side of the terminal end 44b of the partition 44. As a result, the refrigerant flows in from the inlet 28, flows in a spiral shape along the peripheral side surface 39 within the motor refrigerant flow path 40, and is discharged from the outlet 29 to the cooling path 26.

6, in a front view, the inlet 28 and the outlet 29 are provided above the horizontal center line LCL. The horizontal center line LCL is a virtual line that passes through the rotation axis P, which is the center point of the motor M (main body part 34), and extends in the left-right direction (width direction) of the machine. Furthermore, it is preferable that the inlet 28 and the outlet 29 are disposed above the upper end of the side plate 2B. Moreover, the inlet 28 and the outlet 29 are provided on the left and right sides (width direction) of the vertical center line VCL. The vertical center line VCL is a virtual line that passes through the rotation axis P, which is the center point of the motor M (main body part 34), and extends in the up-down direction (height direction) of the machine. For example, in a front view, the inlet 28 is provided in the left region of the motor M, and the outlet 29 is provided in the right region of the motor M.

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 and the rotation axis P, and the horizontal center line LCL, is 30° or more and 55° or less. It is also preferable that the interior angle θ2 formed by the line segment connecting the center of the outlet of the discharge section 29 and the rotation axis P, and the horizontal center line LCL, is 30° or more and 55° or less.

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.

Furthermore, the inlet section 28 is preferably provided in an area surrounded by the horizontal center line LCL, the vertical center line VCL, and the vertical left end line VLL (first vertical line) in a front view. The vertical left end 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, the outlet section 29 is preferably provided in an area surrounded by the horizontal center line LCL, the vertical center line VCL, and the vertical right end line VRL (second vertical line) in a front view. The vertical right end 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.

As a result, when viewed from the front, the inlet section 28 and the outlet section 29 are positioned inside the top, bottom, left and right ends of the motor M (main body section 34 and mounting plate 35). Therefore, the motor M including the inlet section 28 and the outlet section 29 is efficiently positioned inside the machine body.

In addition, when viewed from the front, the three-phase power terminal 37 is located below the horizontal center line LCL. Similarly, the signal terminal 38 is located near the horizontal center line LCL in the up-down direction.

As a result, the three-phase power supply terminals 37 and signal terminals 38, and the inlet section 28 and outlet section 29 are positioned above and below the motor M. Therefore, even if the refrigerant leaks from the inlet section 28 or outlet section 29, the refrigerant is prevented from adhering to the three-phase power supply terminals 37 and signal terminals 38. As a result, problems caused by the refrigerant in the three-phase power supply terminals 37 and signal terminals 38 are prevented.

Furthermore, it is preferable that the three-phase power 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 relative to the three-phase power terminal 37. For example, the signal terminal 38 is provided near the right end of the main body portion 34 of the motor M.

High-frequency, high-voltage three-phase AC is input to the three-phase power 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.

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

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 of the core. A plurality of outlets 46 are provided along the motor coolant flow path 40. The outlets 46 are eventually formed with lids.

[Inverter]
Next, a configuration including a cooling configuration for the inverter 14 will be described with reference to FIGS. 3 and 5 and with reference to FIGS. 8 to 11.

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

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.

Capacitor 51 smoothes the DC current supplied from the 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 to capacitor 51 after inverter 14 is stopped.

The inverter case 50 is composed of an outer plate including a mounting plate 50A, and an enclosed space surrounded by the outer plate 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.

The capacitor 51, IGBT 52, and resistor 53 generate heat during operation and may fail due to the heat. For this reason, the inverter 14 is provided with an inverter refrigerant flow path 55 that cools the components to be cooled, such as the capacitor 51, IGBT 52, and resistor 53.

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

The inverter refrigerant flow path 55 is formed inside the mounting plate 50A along the components to be cooled so as to cool the components of the inverter 14. In the example of FIG. 8, the capacitor 51, the IGBT 52, and the resistor 53 are held on the upper surface of the mounting plate 50A, so the inverter refrigerant flow path 55 is formed inside the mounting plate 50A, below the capacitor 51, the IGBT 52, and the resistor 53.

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

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

Similarly, IGBT 52 generates a large amount of heat compared to capacitor 51 and resistor 53 because it generates a high-voltage AC current (three-phase AC), but has a higher heat resistance temperature than capacitor 51, making it more likely that capacitor 51 will fail first. Also, resistor 53 is less likely to fail due to heat than capacitor 51 and IGBT 52, so there is less need to cool it.

As described above, the refrigerant cools the capacitor 51, the IGBT 52, and the resistor 53 in that order, so the capacitor 51 is cooled first and efficiently. If the condenser 51 is cooled after the IGBT 52, the refrigerant will be significantly warmer after cooling the IGBT 52, making it difficult to sufficiently cool the condenser 51. Conversely, even if the refrigerant is warmed by cooling the condenser 51, the IGBT 52 generates a large amount of heat and becomes hotter than the refrigerant, and the IGBT 52 has a higher thermal resistance than the capacitor 51, so it can sufficiently cool the IGBT 52. Furthermore, the resistor 53 requires less cooling than the capacitor 51 and the IGBT 52.

As a result of the above, the inverter refrigerant flow path 55 is formed so that cooling is performed in the order of the capacitor 51, the IGBT 52, and the resistor 53, so that the capacitor 51, the IGBT 52, and the resistor 53 can be efficiently cooled according to their characteristics.

For example, the inverter refrigerant flow path 55 runs from the inlet 56 along the condenser 51 toward the rear of the aircraft, makes a U-turn near the rear end of the condenser 51, and runs along the condenser 51 toward the front of the aircraft. The inverter refrigerant flow path 55 then makes another U-turn forward of the IGBT 52, and runs toward the rear of the aircraft along the IGBT 52 while widening the width of the flow path (width in the left-right direction of the aircraft). The inverter refrigerant flow path 55 then narrows the width of the flow path as it runs toward the rear of the aircraft, passing through the resistor 53 and reaching the outlet 57.

With this configuration, the refrigerant flowing through the inverter refrigerant flow path 55 can efficiently cool the capacitor 51, the IGBT 52, and the resistor 53.

<IGBT Cooling Structure>
9, the IGBT 52 includes a heat sink. The heat sink may be a fin or the like, but may also be a pin fin 52A provided in a matrix on one surface of the IGBT 52.

Through holes 50B are provided in the mounting plate 50A in the area where the IGBT 52 is arranged. The through holes 50B penetrate from the sealed space of the inverter case 50 to the inverter refrigerant flow path 55. The IGBT 52 is supported by the mounting plate 50A so that the pin fins 52A are arranged in the through holes 50B. The pin fins 52A then pass through the through holes 50B to reach the inverter refrigerant flow path 55.

As a result, the pin fins 52A are in direct contact with the refrigerant flowing through the inverter refrigerant flow path 55, so the IGBT 52 can be efficiently cooled via the pin fins 52A.

Furthermore, it is preferable that the inner diameter of the inverter refrigerant flow path 55 is narrowed at the position where the pin fin 52A of the inverter refrigerant flow path 55 protrudes. For example, at the position where the pin fin 52A of the inverter refrigerant flow path 55 protrudes, the mounting plate 50A facing the pin fin 52A has a protruding portion 50C that protrudes toward the inside of the inverter refrigerant flow path 55.

At the position where the pin fins 52A of the inverter refrigerant flow path 55 protrude, the inner diameter of the inverter refrigerant flow path 55 narrows, increasing the flow rate of the refrigerant flowing through this portion, allowing the refrigerant to efficiently cool the IGBT 52 via the pin fins 52A. In addition, the refrigerant comes into contact with the pin fins 52A with precision, allowing the IGBT 52 to be cooled with precision via the pin fins 52A.

As shown in Figures 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.

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

<Condenser cooling structure>
11 , capacitor 51 is supported on the surface of mounting plate 50A in an enclosed space. At least the area of the bottom surface of capacitor 51 near 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 inverter refrigerant flow path 55 is in surface contact with mounting plate 50A and in close contact therewith.

By bringing the capacitor 51 and the mounting plate 50A into surface contact and tightly adhering to each other, the refrigerant flowing through the inverter refrigerant flow path 55 can efficiently exchange heat with the condenser 51 via the mounting plate 50A, thereby efficiently cooling the condenser 51.

In addition, a refrigerant reservoir 55A is provided near the inlet 56 of the inverter refrigerant flow path 55. For example, the refrigerant reservoir 55A is provided in the inverter refrigerant flow path 55, from the inlet 56 to the end region on the inlet 56 side of the region along the capacitor 51.

The refrigerant reservoir 55A is configured so that the refrigerant flow diameter, which is the vertical cross-sectional area of the refrigerant flow path, is larger than the flow diameter of the other inverter refrigerant flow paths 55, and can store the refrigerant. This allows the refrigerant to be stored in the inverter refrigerant flow path 55 and sufficient refrigerant to be supplied to the inverter refrigerant flow path 55, so that the components to be cooled that are mounted on the inverter 14 can be efficiently cooled.

<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.

The capacitor 51 is in high 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. In addition, if 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. In addition, the operating status of the inverter 14 can be confirmed based on the measured water temperature (temperature of the refrigerant).

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 (temperature of the refrigerant) 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 flow rate of the refrigerant or the inverter 14 can be stopped. Also, if the water temperature (temperature of the refrigerant) measured by the water temperature sensor 59 is about room temperature, it can be determined that the inverter 14 is not operating, and control can be performed to stop the flow of the refrigerant flowing through at least the inverter 14 (inverter refrigerant flow path 55). This allows the inverter 14 to be cooled efficiently and accurately.

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.

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

[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, the motor M, and the DC/DC converter 21 in this order, and the refrigerant may flow through the inverter 14, the motor M, and the DC/DC converter 21 in any order depending on the amounts of heat generated and the thermal resistance of the inverter 14, the motor M, and the DC/DC converter 21.

This allows the cooling mechanism to be configured efficiently according to the characteristics of the object to be cooled.

(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 is a path that returns the refrigerant flowing out of the motor M directly to the radiator 23 without circulating it through the DC/DC converter 21.

Conversely, the cooling mechanism (cooling path 26) may be configured to cool other objects in addition to at least one of the inverter 14, the motor M, and the DC/DC converter 21.

As a result, the cooling mechanism (cooling path 26) can be configured with a high degree of freedom, and the cooling mechanism can cool a variety of cooling targets. For example, a battery or charger can be placed midway along the cooling path 26, and the battery or charger can be cooled by the cooling mechanism.

(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 can be arbitrary. By optimizing the arrangement of these depending on the characteristics and operating conditions of the object to be cooled, the object to be cooled can be cooled efficiently.

(4) In each of the above embodiments, the motor coolant flow passage 40 may be a spiral flow passage that turns around the circumferential surface 39 any number of times. The length of the motor coolant flow passage 40, which is proportional to the number of turns of the spiral, is determined by the number of times that the partition wall 44 turns around the circumferential surface 39 along the circumferential surface 39.

This allows the motor coolant flow path 40 to be easily configured to an appropriate length depending on the characteristics of the motor M, allowing the motor M to be efficiently cooled.

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

(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.

This allows the components that require cooling to be efficiently cooled to the required extent depending on the required configuration of the inverter 14.

(7) In each of the above embodiments, the electric work vehicle can adopt any running device, such as crawlers, instead of the front wheels 10 and rear wheels 11.

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

The present invention can be applied to electric work vehicles that perform various tasks, such as agricultural work.

4 Running battery 10 Front wheels (running device)
11 Rear wheels (running gear)
14 inverter 21 DC/DC converter 23 radiator 26 cooling path M motor

Claims (5)

The aircraft and
A running device provided on the airframe;
A motor that drives the traveling device;
an inverter that supplies power to the motor;
Electrical components and
a DC/DC converter that converts the voltage of the power supplied to the electrical component;
A radiator for cooling the refrigerant;
a cooling path through which the coolant cooled by the radiator circulates around the motor, the inverter, and the DC/DC converter to the radiator;
the cooling path passes from the radiator through the inverter, the motor, and the DC/DC converter in this order, and returns to the radiator;
In a plan view, a portion of the cooling path extending from the motor to the DC/DC converter does not overlap with the inverter,
An electric work vehicle , wherein a portion of the cooling path extending from the motor to the DC/DC converter does not overlap with the inverter in a side view . The electric work vehicle according to claim 1, in which the forward direction of the vehicle is the front, and the radiator, the inverter, and the motor are arranged in the fore-and-aft direction of the vehicle, in that order from front to back. The electric work vehicle according to claim 2, wherein the DC/DC converter is disposed on one side of the radiator in a left-right direction perpendicular to the front-rear direction. a portion of the cooling path extending from the inverter to the motor is connected to the motor on the other side of the motor in the left-right direction;
The electric work vehicle according to claim 3 , wherein a portion of the cooling path extending from the motor to the DC/DC converter is connected to the motor on the one side of the motor. a battery for driving the vehicle that stores the electric power supplied to the motor via the inverter;
the inverter is disposed below the driving battery,
The electric work vehicle according to claim 2 , wherein the inverter overlaps with the traction battery in a plan view.

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