JP2023095637A - Electrically-driven mobile vehicle - Google Patents

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

The present invention relates to an electric working vehicle in which a traveling device is driven by a motor.

An electric working vehicle drives a traveling device with a motor. A three-phase current (three-phase alternating current) that drives the motor is generated by an inverter. The inverter includes power transistors such as IGBTs that generate three-phase alternating current with a predetermined frequency. Since the IGBT in operation generates a large amount of heat, it is cooled by a coolant.

For example, as shown in Patent Document 1, an IGBT (power transistor) is cooled by a laminated cooler through which a coolant passes.

JP 2016-152637 A

However, the inverter includes capacitors, resistors, etc. in addition to the IGBTs, and these need to be cooled. In addition, there is a demand for more efficient cooling of inverter components including IGBTs.

SUMMARY OF THE INVENTION An object of the present invention is to efficiently cool inverter components.

In order to achieve the above object, an electric working vehicle according to an embodiment of the present invention includes a machine body, a traveling device provided on the machine body, a motor for driving the traveling device, and an inverter for supplying power to the motor. a radiator for cooling a coolant; and a cooling path through which the coolant cooled by the radiator circulates around at least the inverter to the radiator, the inverter including a mounting plate and an inverter case forming a sealed space. a capacitor held by the mounting plate in the sealed space for smoothing the input DC current; and a DC current supplied from the capacitor held by the mounting plate in the sealed space at a predetermined frequency. a power transistor that converts to three-phase alternating current, a resistor that is held by the mounting plate in the sealed space and discharges the power of the inverter, and a resistor that is provided inside the mounting plate and circulates in the inverter, an inverter coolant flow path through which the coolant for cooling the capacitor, the power transistor, and the resistor flows; the power transistor has a heat sink; and the inverter coolant flow path penetrates toward the closed space. The heat sink penetrates through the through hole and protrudes into the inverter coolant flow path.

With such a configuration, the capacitor, power transistor, and resistor mounted on the inverter are efficiently cooled by heat exchange with the refrigerant through the mounting plate of the inverter case.

Also, the heat sink of the power transistor penetrates through the through hole of the mounting plate and protrudes into the inverter coolant channel. With such a configuration, the heat sink is in direct contact with the coolant, so that the power transistor, which generates a large amount of heat, can be efficiently dissipated and cooled.

Moreover, it is preferable that the inverter includes an O-ring closing a space between an outer peripheral portion of the power transistor and an inner peripheral portion of the through hole.

With such a configuration, the airtightness between the power transistor and the inverter case is improved, and leakage of refrigerant into the inverter case through the through holes is suppressed.

In addition, it is preferable that the inverter coolant channel has a protruding portion in which the mounting plate protrudes toward the power transistor in a region that overlaps with the arrangement position of the power transistor in the inverter coolant channel.

With such a configuration, the inverter coolant channel narrows toward the power transistor in the projecting region of the heat sink, which is the position where the inverter coolant channel cools the power transistor. As a result, the coolant flows accurately while being in contact with the heat sink, the flow velocity of the coolant increases, and the power transistor can be efficiently cooled.

In addition, the inverter coolant channel may have a coolant reservoir in the coolant inflow region, and the cross-sectional area of the coolant reservoir may be larger than the cross-sectional area of the other inverter coolant channels.

With such a configuration, the refrigerant that has flowed into the inverter refrigerant flow path is temporarily stored in the refrigerant reservoir, and a sufficient amount of refrigerant flows out into the inverter refrigerant flow path. As a result, the inside of the inverter coolant flow path is filled with the coolant with high accuracy, and the coolant can efficiently cool the components such as the capacitor, the power transistor, and the resistor.

Also, the coolant may cool the capacitor, the power transistor, and the resistor in this order.

In general, capacitors have lower heat resistance than power transistors. Power transistors generate more heat during operation than capacitors. Resistors are less likely to thermally fail than capacitors and power transistors, so cooling needs are less. In addition, the refrigerant cools the object to be cooled by exchanging heat with the object to be cooled. Furthermore, since the power transistor generates a large amount of heat, the cooling capacity of the coolant after cooling the power transistor is lowered. From the above, it is preferable to preferentially cool the condenser. Also, the coolant preferably cools the capacitor before cooling the power transistor.

Therefore, the inverter coolant flow path is formed so that the coolant cools the capacitor, the power transistor, and the resistor in that order, so that the capacitor, the power transistor, and the resistor can be cooled efficiently and in a well-balanced manner.

Further, a temperature sensor for measuring the temperature of the coolant may be provided between a position for cooling the capacitor and a position for cooling the power transistor in the inverter coolant flow path.

As mentioned above, it is preferable to preferentially cool the condenser. Moreover, since the power transistor generates a large amount of heat, it is important to control the temperature of the coolant flowing through the power transistor in order to sufficiently cool the power transistor.

Therefore, if the temperature of the refrigerant after cooling the condenser is too high, it can be determined that the condenser may not be sufficiently cooled. can judge. Further, if the temperature of the coolant after cooling the condenser is too high, it can be determined that the condenser is not sufficiently cooled, or that there is a possibility that the power transistor cannot be sufficiently cooled.

As described above, the cooling efficiency of the capacitor and the power transistor is confirmed by measuring the temperature of the coolant flowing between the capacitor and the power transistor in the inverter coolant flow path, and the capacitor and the power transistor are efficiently cooled. be able to.

For example, if the measured temperature of the coolant is about room temperature, it can be determined that the amount of heat generated by the capacitor is small or sufficiently cooled, and it can be determined that the power transistor can be cooled with high accuracy. Therefore, control can be performed to reduce or stop the circulation speed of the refrigerant. Further, if the measured temperature of the refrigerant is equal to or higher than a predetermined temperature, control can be performed to increase the circulation speed of the refrigerant, and control such as stopping the operation of the inverter can be performed as necessary. can.

It is a left view of a tractor. 1 is a front view of a tractor; FIG. FIG. 4 is a left side view illustrating the arrangement of inverters and the like; It is a figure which shows the flow of power transmission. 4 is a plan view illustrating a schematic configuration of a cooling path; FIG. FIG. 4 is a front view illustrating the essential parts of the arrangement of motors; FIG. 3 is a perspective view illustrating a schematic configuration of a motor coolant flow path; FIG. 2 is a plan view illustrating a configuration of main parts of an inverter; FIG. 9 is a cross-sectional left side view showing a main part of a cross section taken along IX-IX in FIG. 8; It is a bottom view which illustrates a structure of IGBT. FIG. 9 is a cross-sectional left side view showing a main part of a cross section taken along line XI-XI of FIG. 8;

A mode for carrying out the present invention will be described based on the drawings. In the following description, unless otherwise specified, the direction of arrow F is "forward", the direction of arrow B is "back", the direction of arrow U is "up", and the direction of arrow D is "up". Let the direction of arrow L be "down", the direction of arrow R be "left", and the direction of arrow R be "right".

[Overall configuration of tractor]
An electric tractor (hereinafter simply referred to as a tractor) will be described below as an example of an electric work vehicle. As shown in FIGS. 1 and 2 , the tractor includes left and right front wheels 10 , left and right rear wheels 11 , and a cover member 12 .

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

The cover member 12 is arranged at the front part of the fuselage. The operating section 3 is provided behind the cover member 12 . In other words, the cover member 12 is arranged in front of the driving section 3 .

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

The tractor has a battery 4 for running. Further, the cover member 12 is configured to be swingable around an opening/closing axis Q extending in the lateral direction of the machine body. Thereby, the cover member 12 is configured to be openable and closable. When cover member 12 is closed, driving battery 4 is covered with cover member 12 .

The tractor includes an inverter 14 and a motor M, as shown in FIGS. The running battery 4 supplies electric power to the inverter 14 . Inverter 14 converts the DC power from running battery 4 into AC power (three-phase AC) and supplies it to motor M. FIG. The motor M is driven by AC power supplied from the inverter 14 .

As shown in FIGS. 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.

The hydraulic pump 15a is driven by rotational power supplied from the motor M. As shown in FIG. Rotational power is output from the hydraulic motor 15b by driving the hydraulic pump 15a. Note that the hydrostatic continuously variable transmission 15 changes the rotational power between the hydraulic pump 15a and the hydraulic motor 15b. Further, the hydrostatic continuously variable transmission 15 is configured so that the gear ratio can be changed steplessly.

Rotational power output from the hydraulic motor 15 b is transmitted to the transmission 16 . The rotational power transmitted to the transmission 16 is changed in speed by a gear transmission mechanism of the transmission 16 and distributed to the left and right front wheels 10 and the left and right rear wheels 11 . As a result, the left and right front wheels 10 and the left and right rear wheels 11 are driven.

The tractor also has a mid PTO shaft 17 and a rear PTO shaft 18, as shown in FIGS. 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. Thereby, the mid PTO shaft 17 and the rear PTO shaft 18 rotate.

If a working device is connected to the mid PTO shaft 17 or the rear PTO shaft 18, the rotational power of the mid PTO shaft 17 or the rear PTO shaft 18 drives the working device. For example, as shown in FIG. 3, a mower 19 is connected to the mid PTO shaft 17 in this embodiment. The rotary power of the mid PTO shaft 17 drives the lawn mower 19 .

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

Inverter 14 and motor M generate heat during operation. Therefore, the inverter 14 and the motor M are cooled during operation in order to suppress failures due to heat. The tractor cooling mechanism will be described below with reference to FIGS. 3 and 5. FIG.

Here, in addition to the inverter 14 and the motor M, the tractor has a DC/DC converter 21 as a device that generates heat during operation. The DC/DC converter 21 supplies electric power to various auxiliary machines of the tractor. The DC/DC converter 21 drops (converts) the electric power supplied from the running battery 4 to a voltage corresponding to each auxiliary machine, and supplies the electric power to each auxiliary machine.

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

Radiator 23 cools the coolant that cools inverter 14 , motor M, and DC/DC converter 21 . The radiator 23 cools the coolant with the air that flows from the front of the fuselage. The refrigerant cools the object to be cooled that has generated heat by exchanging heat with the object to be cooled.

The cooling path 26 is a path through which a coolant flows, and is a path from the radiator 23 to the object to be cooled and returned to the radiator 23 . The cooling path 26 is a pipe-shaped member having a hollow interior and an arbitrary cross-sectional shape, and a coolant flows through the hollow portion.

The electric pump 24 sucks the cooled coolant from the radiator 23 and circulates it through the cooling path 26 . The coolant may be cooling water, antifreeze liquid, cooling gas, etc., as long as it can flow through the cooling path 26 and appropriately exchange heat with the object to be cooled.

Specifically, the radiator 23 is provided in the center portion in the left-right direction of the fuselage in the front portion of the fuselage and slightly eccentric to the left lateral side. Also, the DC/DC converter 21 is provided on the right lateral side of the radiator 23 so as to be aligned with the radiator 23 in the left-right direction. Since the radiator 23 and the DC/DC converter 21 are provided in the front part of the fuselage, it is easy for air to flow from the front of the fuselage.

The electric pump 24 is provided behind and below the radiator 23 in the vicinity of the central portion in the left-right direction of the fuselage.

The inverter 14 is provided in the vicinity of the central portion in the left-right direction of the aircraft on the rear side of the radiator 23 . Inverter 14 is provided below running battery 4 and is arranged to overlap running battery 4 in a plan view. For example, the inverter 14 is provided inside the arrangement area of the running battery 4 in plan view.

The motor M is provided in the vicinity of the central portion in the left-right direction of the aircraft on the rear side of the inverter 14 . In addition, the motor M is provided below the driving battery 4 and overlaps the driving battery 4 in a plan view. For example, the motor M is provided inside the arrangement area of the driving battery 4 in plan view.

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 coolant through the cooling path 26 , circulates the coolant in the order of the inverter 14 , the motor M, and the DC/DC converter 21 , and then circulates it to the radiator 23 .

The refrigerant discharged from electric pump 24 flows through cooling path 26B of cooling path 26 to inverter 14 . For example, the cooling path 26B is provided upward through the right side of the electric pump 24 and connected to the right front portion of the inverter 14 .

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

The coolant that has flowed through the motor M flows out to the cooling path 26</b>D of the cooling path 26 from a discharge portion 29 provided on the right side and upper side of the motor M. The refrigerant flowing out of the motor M is circulated to the DC/DC converter 21 through the cooling path 26D. For example, the cooling path 26</b>D is connected to the DC/DC converter 21 through the right side and below the inverter 14 .

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

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

Here, since the inverter 14 generates a three-phase alternating current for controlling the motor M, it generally has lower heat resistance than the motor M and tends to generate high heat compared to the DC/DC converter 21 . Therefore, the inverter 14 needs to be sufficiently cooled in order to suppress failure due to the influence of heat, and is preferably cooled preferentially compared to the motor M and the DC/DC converter 21 .

Also, although the motor M generally has higher heat resistance than the inverter 14 , it generates a larger amount of heat than the inverter 14 .

DC/DC converter 21 generates less heat than inverter 14 and motor M, and needs to be cooled less. In addition, since the DC/DC converter 21 is arranged at a position where air can easily flow, it can be expected to be cooled by the air.

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

Thus, the coolant 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 heat exchange with the object to be cooled. Therefore, the temperature of the coolant flowing through the motor M, which generates a large amount of heat, rises compared to that after flowing through the inverter 14, and the cooling capacity of the coolant after flowing through the motor M greatly decreases. After being cooled by the radiator 23, the coolant first circulates through the inverter 14, which has a high cooling priority, before the motor M. Inverter 14 can be cooled.

Since the amount of heat generated by the inverter 14 is smaller than that of the motor M, the refrigerant retains a sufficient cooling capacity even after flowing through the inverter 14, and can sufficiently 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 for the refrigerant is also small. 21 can be cooled.

As described above, the cooling mechanism according to the present embodiment can efficiently cool the inverter 14 , the motor M, and the DC/DC converter 21 with the refrigerant flowing through the cooling path 26 .

〔motor〕
Next, the cooling structure and arrangement structure of the motor M will be described using FIGS. 6 and 7 while referring to FIGS. 3 and 5. FIG.

As shown in FIG. 6, the body frame 2 includes a plate-like 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 end portions of the bottom plate 2A in the left-right direction (width direction) of the machine body. The vertical plate 2C is a plate-like member and is provided so as to be orthogonal to each of the bottom plate 2A and the pair of side plates 2B.

The motor M is arranged above the bottom plate 2A and is cantilevered on the front surface of the vertical plate 2C. The motor M includes a body portion 34 and a plate-shaped mounting plate 35 provided at the rear portion of the body portion 34 . A mounting plate 35 of the motor M is supported on the front surface of the vertical plate 2C. Also, the motor M has a body portion 34 arranged between the pair of side plates 2B. In addition, the hydraulic pump 6 is supported on the front surface of the vertical plate 2C so as to be laterally aligned with the motor M with one of the side plates 2B interposed therebetween. The hydraulic pump 6 is driven by a motor M and supplies hydraulic fluid to hydraulic equipment.

The motor M has a three-phase power supply terminal 37 on the front surface of the motor M to which a three-phase alternating current (three-phase current) is input. Further, the motor M has signal terminals 38 on the front surface of the motor M for inputting and outputting various signals.

The motor M is provided with a stator (not shown) and a rotor (not shown) inside the body portion 34 . A stator is provided along the inside of the peripheral side 39 of the body portion 34 so as to surround the rotor. In the motor M, the rotor rotates around the rotation axis P when a three-phase alternating current is input to the stator. Driving force is transmitted to the hydrostatic continuously variable transmission 15 by rotating the rotor.

As shown in FIG. 7 , the motor M includes a spiral motor coolant flow path 40 along the peripheral side surface 39 of the body portion 34 . Peripheral side 39 is double-walled, with motor coolant flow between an inner inner perimeter side 39A and an outer outer perimeter side 39B (partially omitted in FIG. 7 to illustrate the internal structure). A path 40 is formed.

A concave portion 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 concave portion. A region 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 serves as the motor coolant flow path 40. As shown in FIG.

A partition wall 44 is provided inside the motor coolant channel 40 . The partition wall 44 is provided obliquely with respect to the circumferential direction of the peripheral side surface 39 from a position contacting the front end face 41 to a position contacting the rear end face 42 . The length in the circumferential direction of the peripheral side surface 39 of the partition wall 44 is about 1/4 of the length in the circumferential direction (length of the circumference) of the peripheral side surface 39 . The partition wall 44 is provided along the inner peripheral side surface 39A and the outer peripheral side surface 39B, and is in contact with the inner peripheral side surface 39A and the outer peripheral side surface 39B. As a result, the motor coolant channel 40 has a helical shape extending from the starting end portion 44 a of the partition wall 44 in contact with the front end surface 41 to the terminal end portion 44 b in contact with the rear end surface 42 . The length of the motor coolant channel 40 is approximately the sum of the length of the peripheral side surface 39 in the circumferential direction and the length of the partition wall 44 .

With such a configuration, the length of the motor coolant channel 40 can be efficiently increased on the peripheral side surface 39 of the motor M, and the motor M can be efficiently cooled.

The motor coolant flow path 40 has an inflow portion 28 serving as an inlet through which the coolant flowing through the cooling path 26 flows into the motor coolant flow path 40 , and an outlet through which the coolant that has flowed through the motor coolant flow path 40 is discharged to the cooling path 26 . and a discharge portion 29 that becomes

The inflow portion 28 extends from the motor coolant channel 40 through the outer peripheral side surface 39B and is provided in a region adjacent to the discharge portion 29 side of the starting end portion 44a of the partition wall 44 . The discharge portion 29 extends from the motor coolant channel 40 through the outer peripheral side surface 39B and is provided in a region adjacent to the inflow portion 28 side of the terminal end portion 44b of the partition wall 44 . As a result, the coolant flows in from the inflow portion 28 , spirally circulates along the peripheral side surface 39 in the motor coolant flow path 40 , and is discharged from the discharge portion 29 to the cooling path 26 .

As shown in FIG. 6, in a front view, the inflow portion 28 and the discharge portion 29 are provided above the horizontal center line LCL. The horizontal center line LCL is an imaginary line extending in the left-right direction (width direction) of the machine body through the rotation axis P, which is the center point of the motor M (body portion 34). Furthermore, the inflow portion 28 and the discharge portion 29 are preferably arranged above the upper end portion of the side plate 2B. Further, the inflow portion 28 and the discharge portion 29 are distributed to the left and right (width direction) with respect to the vertical center line VCL. The vertical center line VCL is an imaginary line extending in the vertical direction (height direction) of the machine body passing through the rotation axis P, which is the center point of the motor M (body portion 34). For example, the inflow portion 28 is provided on the left side of the motor M and the discharge portion 29 is provided on the right side of the motor M when viewed from the front.

In particular, the inner angle θ1 formed by the line segment connecting the center of the inlet of the inlet portion 28 and the rotation axis P and the horizontal center line LCL is preferably 30° or more and 55° or less. Further, it is preferable that the inner angle θ2 formed by the line segment connecting the center of the outflow port of the discharge portion 29 and the rotation axis P and the horizontal center line LCL is 30° or more and 55° or less.

By arranging the inflow portion 28 and the discharge portion 29 in this manner, the inflow portion 28 and the discharge portion 29 can efficiently connect the motor coolant passage 40 and the cooling passage 26, The section 28 and the discharge section 29 are efficiently arranged.

Furthermore, the inflow portion 28 is preferably provided in a region surrounded by a horizontal center line LCL, a vertical center line VCL, and a vertical left edge line VLL (first vertical line) when viewed from the front. The vertical left edge line VLL is an imaginary line that passes through the left edge of the motor M and extends in the vertical direction (height direction) of the machine body. Similarly, the discharge portion 29 is preferably provided in a region surrounded by a horizontal center line LCL, a vertical center line VCL, and a vertical right edge line VRL (second vertical line) when viewed from the front. The vertical right edge line VRL is an imaginary line passing through the right edge of the motor M and extending in the vertical direction (height direction) of the machine body.

As a result, in a front view, the inflow portion 28 and the discharge portion 29 are arranged inside the upper, lower, left, and right end portions of the motor M (the main body portion 34 and the mounting plate 35). Therefore, the motor M including the inflow portion 28 and the discharge portion 29 is efficiently arranged inside the airframe.

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

As a result, the three-phase power supply terminal 37 and the signal terminal 38, and the inflow portion 28 and the discharge portion 29 are arranged vertically apart from each other. Therefore, even if the refrigerant leaks from the inflow portion 28 or the discharge portion 29, the adhesion of the refrigerant to the three-phase power terminal 37 and the signal terminal 38 is suppressed. As a result, the three-phase power terminal 37 and the signal terminal 38 are prevented from malfunctioning due to the refrigerant.

Furthermore, the three-phase power terminal 37 is arranged in the center in the left-right direction (width direction) of the fuselage, and the signal terminal 38 is located on the left or right side of the vertical center line VCL. It is preferably arranged eccentrically (in the width direction). For example, the signal terminals 38 are provided near the right end of the body portion 34 of the motor M. As shown in FIG.

A high-frequency, high-voltage three-phase alternating current is input to the three-phase power supply terminal 37, and in order to control the rotation speed of the motor M, the frequency and voltage must be stably input. Also, various control signals and detection signals are input/output to/from the signal terminal 38 .

Therefore, by arranging the three-phase power terminal 37 and the signal terminal 38 apart in the up-down direction (height direction) and left-right direction (width direction) of the machine body, the three-phase power terminal 37 and the signal terminal 38 are restrained from being affected by noise, and the motor M can be operated with high accuracy.

Further, the case portion including the motor coolant flow path 40 of the motor M is manufactured by casting. Also, the motor coolant flow path 40 is molded using a core made of sand. Therefore, the motor coolant flow path 40 of the body portion 34 is provided with a discharge port 46 for discharging core sand. A plurality of outlets 46 are provided along the motor coolant flow path 40 . The outlet 46 is finally capped.

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

The inverter 14 converts the direct current supplied from the running battery 4 into a three-phase alternating current (three-phase current/three-phase power supply) of a predetermined frequency, and supplies the motor M with the three-phase alternating current.

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

Capacitor 51 smoothes the DC current supplied from running battery 4 . The IGBT 52 converts the direct current smoothed by the capacitor 51 into a three-phase alternating current of a predetermined frequency, and supplies the motor M with the three-phase alternating current. A resistor 53 is a power consumption resistor provided to discharge the current charged in the capacitor 51 after the inverter 14 is stopped.

The inverter case 50 is composed of outer plates including a mounting plate 50A, and a closed space surrounded by the outer plates is formed inside the inverter case 50 . Capacitor 51, IGBT 52, and resistor 53 are supported by mounting plate 50A in a sealed space.

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

The inverter coolant flow path 55 is a flow path provided inside the mounting plate 50A and through which the coolant introduced from the cooling path 26 flows. The inverter case 50 includes an inflow portion 56 and a discharge portion 57, and the refrigerant flowing through the cooling path 26 (cooling path 26B) flows from the inflow portion 56 into the inverter refrigerant flow path 55, and flows through the inverter refrigerant flow path 55. flows out from the discharge portion 57 to the cooling path 26 (cooling path 26C).

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

For example, the inverter coolant flow path 55 is a path that passes from the inflow portion 56 through a region along the capacitor 51 , a region along the IGBT 52 , and a region 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 the resistor 53 . Therefore, capacitor 51 is a component that needs to be cooled most preferentially in inverter 14 .

Similarly, since the IGBT 52 generates a high-voltage alternating current (three-phase alternating current), it generates more heat than the capacitor 51 and the resistor 53, but has a higher heat resistance than the capacitor 51, and the capacitor 51 fails first. likely to. Resistor 53 is also less likely to fail than capacitor 51 and IGBT 52, and thus requires less cooling.

As described above, the coolant cools the capacitor 51, the IGBT 52, and the resistor 53 in this order, so the capacitor 51 is preferentially cooled and the capacitor 51 is efficiently cooled. If the capacitor 51 is cooled after the IGBT 52, the temperature of the coolant after cooling the IGBT 52 rises significantly, making it difficult to cool the capacitor 51 sufficiently. Conversely, even if the coolant is heated by cooling the capacitor 51, the IGBT 52 generates a large amount of heat and becomes hotter than the coolant. Allow to cool. Resistor 53 also requires less cooling than capacitor 51 and IGBT 52 .

From the above, the inverter coolant 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. Allow to cool.

For example, the inverter coolant flow path 55 extends from the inflow portion 56 along the condenser 51 toward the rear of the aircraft, makes a U-turn near the rear end of the condenser 51, and proceeds along the condenser 51 toward the front of the aircraft. Further, the inverter coolant flow path 55 makes a U-turn again forward of the IGBT 52 and extends toward the rear of the aircraft body along the IGBT 52 while widening the width of the flow path (the width in the lateral direction of the aircraft body). Then, the inverter coolant flow path 55 moves toward the rear of the airframe so as to reach the discharge portion 57 via the resistor 53 while narrowing the width of the flow path.

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

<Cooling structure of IGBT>
As shown in FIG. 9, the IGBT 52 has a heat sink. The heat sink may be a fin or the like, but may be a pin fin 52A provided in a matrix on one surface of the IGBT 52. FIG.

A through-hole 50B is provided in an area of the mounting plate 50A where the IGBTs 52 are arranged. The through hole 50</b>B penetrates 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 such that the pin fins 52A are arranged in the through holes 50B. Then, the pin fins 52A penetrate through the through holes 50B and reach the inverter coolant 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 that the IGBTs 52 can be efficiently cooled via the pin fins 52A.

Furthermore, it is preferable that the inner diameter of the inverter coolant channel 55 be narrowed at the position where the pin fins 52A of the inverter coolant channel 55 protrude. For example, at a position where the pin fins 52A of the inverter coolant channel 55 project, the mounting plate 50A facing the pin fins 52A has a projecting portion 50C that projects toward the inside of the inverter coolant channel 55. As shown in FIG.

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 is narrowed. can be cooled. Further, the coolant comes into contact with the pin fins 52A with high precision, and the IGBT 52 can be cooled with high precision via the pin fins 52A.

As shown in FIGS. 9 and 10, the inverter 14 preferably includes an O-ring 52B that blocks the space 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 peripheral portion of the IGBT 52 and the inner peripheral portion of the through hole 50B.

This suppresses the refrigerant flowing through the inverter refrigerant flow path 55 from flowing into the closed space of the inverter 14 via the through hole 50B. As a result, various parts of the inverter 14 are prevented from malfunctioning due to the refrigerant.

<Condenser cooling structure>
As shown in FIG. 11, the capacitor 51 is supported on the surface of the mounting plate 50A within the sealed space. At least the vicinity of the area along the inverter refrigerant flow path 55 on the bottom surface of the capacitor 51 is formed smooth and flush. At least the vicinity of the area where the capacitor 51 is mounted on the mounting plate 50A is formed to be smooth and flush. Therefore, at least the vicinity of the region along the inverter refrigerant flow path 55 of the capacitor 51 is in surface contact with the mounting plate 50A and is in close contact.

Since the condenser 51 and the mounting plate 50A are in close contact with 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. can cool the condenser 51 to

A refrigerant reservoir 55</b>A is provided in the vicinity of the inflow portion 56 of the inverter refrigerant channel 55 . For example, the refrigerant storage portion 55A is provided in the inverter refrigerant flow path 55 from the inflow portion 56 to the end portion of the area along the condenser 51 on the side of the inflow portion 56 .

The coolant storage part 55A has a coolant flow diameter, which is a cross-sectional area in the vertical direction of the coolant flow channel, larger than the flow diameter of the other inverter coolant flow channels 55, and is configured to store the coolant. As a result, the refrigerant can be stored in the inverter refrigerant flow path 55 and a sufficient amount of refrigerant can be supplied into the inverter refrigerant flow path 55, so that the components to be cooled mounted in the inverter 14 can be efficiently cooled. be able to.

<Other structures>
As shown in FIG. 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 that is the refrigerant. The water temperature sensor 59 is provided, for example, between the cooling area of the capacitor 51 and the cooling area of the IGBT 52 in the inverter refrigerant flow path 55 . More specifically, the water temperature sensor 59 is provided at a U-turn portion of the inverter refrigerant flow path 55 in the cooling area of the condenser 51 or the like.

The condenser 51 has a high need for cooling, and after cooling the condenser 51 or when the temperature of the refrigerant during cooling reaches or exceeds a predetermined temperature, it can be determined that the condenser 51 is not sufficiently cooled. Also, if the temperature of the coolant that cools the IGBT 52 is higher than 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 (refrigerant temperature).

Therefore, the temperature of the cooling water (refrigerant) is measured by the water temperature sensor 59, and the flow velocity 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, when 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 flow velocity of the refrigerant, or the inverter 14 can be stopped. If the water temperature (refrigerant temperature) measured by the water temperature sensor 59 is about room temperature, it is determined that the inverter 14 is not operating, and at least the refrigerant flowing through the inverter 14 (inverter refrigerant flow path 55) is stopped. It can be controlled to stop. Thereby, the inverter 14 can be cooled efficiently and accurately.

Inverter 14 also includes a current sensor 58 that measures the current value of the three-phase alternating current generated by IGBT 52 . The current sensor 58 is supported by the three-phase AC wiring 52C in front of the IGBT 52. As shown in FIG. The IGBT 52 generates a predetermined three-phase alternating current while referring to the current value measured by the current sensor 58 .

The current sensor 58 may be arranged so as to have a region that overlaps with the inverter coolant channel 55 in plan view, or may be provided apart from the inverter coolant channel 55 . The current sensor 58 generates less heat than the IGBT 52 and has less heat resistance than the capacitor 51 . Therefore, the current sensor 58 does not necessarily have to be provided along the inverter refrigerant flow path 55 , and is sufficiently cooled by exchanging heat with the refrigerant through the inverter case 50 .

[Another embodiment]
(1) The heat resistance of the inverter 14 is not always low. Similarly, the amount of heat generated by the motor M is not necessarily high. Therefore, in the above-described embodiment, the cooling path 26 is not limited to the configuration in which the refrigerant flows in the order of the inverter 14, the motor M, and the DC/DC converter 21. The coolant may be circulated in any order depending on the heat resistance.

Thereby, the cooling mechanism can be efficiently configured according to the characteristics of the object to be cooled.

(2) In each of the above implementations, the cooling mechanism (cooling path 26 ) may be configured to cool at least one of inverter 14 , motor M, and DC/DC converter 21 . For example, the cooling path 26 may be configured so as not to pass through the DC/DC converter 21 . In this case, the cooling path 26 serves as a path for directly returning the coolant flowing out of the motor M to the radiator 23 without circulating it to the DC/DC converter 21 .

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

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 objects to be cooled. For example, the battery and the charger may be arranged in the middle of the cooling path 26, and the battery and the charger may be cooled by a cooling mechanism.

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

(4) In each of the above implementations, the motor coolant channel 40 may be a spiral channel that circles the peripheral side surface 39 any number of times. The length of the motor coolant flow path 40, which is proportional to the number of turns of the spiral, is determined by the number of turns of the partition wall 44 along the circumferential side surface 39. FIG.

As a result, the motor cooling medium flow path 40 having an appropriate length can be easily configured according to the characteristics of the motor M, and the motor M can be efficiently cooled.

(5) In each of the above implementations, the three-phase power supply terminals 37 and the signal terminals 38 can be arranged at arbitrary positions. Thereby, the structure of the motor M can be optimized with a high degree of freedom.

(6) In each of the above implementations, in addition to the capacitor 51, the IGBT 52, the resistor 53, and the current sensor 58, the inverter 14 may include other components to be cooled. Conversely, inverter 14 does not have to include capacitor 51 , IGBT 52 , resistor 53 , or current sensor 58 .

Thereby, according to the required configuration of the inverter 14, the components requiring cooling can be efficiently cooled within the required range.

(7) In each of the above-described embodiments, the electric working vehicle can adopt any traveling device such as a crawler instead of the front wheels 10 and the rear wheels 11 .

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

INDUSTRIAL APPLICABILITY The present invention can be applied to electric working vehicles that perform various types of work such as agricultural work.

10 front wheel (running device)
11 Rear wheel (running device)
14 Inverter 23 Radiator 26 Cooling path 50 Inverter case 50A Mounting plate 50B Penetration hole 50C Projection 51 Capacitor 52 IGBT (power transistor)
52A pin fin (heat sink)
52B O-ring 53 Resistance 55 Inverter refrigerant channel 55A Refrigerant reservoir 59 Water temperature sensor (temperature sensor)
M motor

Claims (6)

Airframe and
a running device provided on the fuselage;
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 to the radiator around at least the inverter;
The inverter is
an inverter case including a mounting plate and forming an enclosed space;
a capacitor held by the mounting plate in the sealed space for smoothing the input direct current;
a power transistor held by the mounting plate in 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 in the sealed space to discharge the power of the inverter;
an inverter coolant flow path provided inside the mounting plate and through which the coolant that circulates in the inverter and cools the capacitor, the power transistor, and the resistor;
the power transistor has a heat sink;
The inverter refrigerant flow path has a through hole penetrating toward the closed space,
The electric working vehicle, wherein the heat sink penetrates the through hole and protrudes into the inverter coolant flow path. 2. The electric working vehicle according to claim 1, wherein the inverter includes an O-ring closing a space between an outer peripheral portion of the power transistor and an inner peripheral portion of the through hole. 3. The electric motor according to claim 1, wherein the inverter coolant channel includes a projecting portion in which the mounting plate protrudes toward the power transistor in a region overlapping an arrangement position of the power transistor in the inverter coolant channel. work vehicle. 4. The inverter coolant channel according to any one of claims 1 to 3, wherein the inverter coolant channel has a coolant reservoir in an inflow region of the coolant, and the cross-sectional area of the coolant reservoir is larger than the cross-sectional area of the other inverter coolant channels. The electric work vehicle described in the paragraph. The electric working vehicle according to any one of claims 1 to 4, wherein the refrigerant cools the capacitor, the power transistor, and the resistor in this order. 6. The electric working vehicle according to claim 5, further comprising a temperature sensor for measuring the temperature of the coolant between a position for cooling the capacitor and a position for cooling the power transistor in the inverter coolant flow path.

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