JP2023123093A - Cooling device for in-wheel motor - Google Patents

Abstract

To provide a cooling device for an in-wheel motor to improve overall cooling efficiency by promoting heat dissipation from lubricating oil that cools a motor.SOLUTION: A cooling pipe 22 that injects lubricating oil pressurized and sent from a pump 18 is arranged at an upper part of the inside of a housing 4, the cooling pipe 22 includes a first pipe portion 22a arranged toward a direction parallel to a rotational center axis of a motor 3 and a second pipe portion 22b arranged toward a direction intersecting the first pipe portion 22a and that communicates with the first pipe section 22a, a discharge hole for discharging lubricating oil downward or in a circumferential direction of the motor 3 is provided in the first pipe portion 22a, and the other discharge hole for discharging the lubricating oil in the direction of the rotational center axis is provided in the second pipe portion 22b.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a device for cooling an in-wheel motor for a vehicle, and more particularly to a device for cooling by radiating heat to the outside air.

An in-wheel motor for a vehicle is a driving device in which a motor that generates drive torque is integrated with a wheel hub, an axle shaft, or the like, and attached to a vehicle body together with a wheel by a suspension device (suspension mechanism). For example, a permanent magnet type synchronous motor may be employed as the motor, and in that case, a control device such as an inverter is also housed inside the casing together with the motor. Also, the motor may be a high-rotation, low-torque motor in order to reduce the size and weight. In this case, a reduction mechanism is provided on the output side of the motor. In this way, the in-wheel motor has a structure in which the members that generate heat when energized, such as the motor, and the members that generate heat due to friction, such as the speed reduction mechanism and bearings, are housed inside the casing in a sealed state. must be cooled by heat dissipation.

An example of a device for cooling an in-wheel motor is described in Patent Document 1. The device described in Patent Document 1 is a device configured to cool a motor and a reduction unit with lubricating oil, and an oil pipe is arranged above the motor and the reduction unit in the axial direction of the motor. The oil pipe is formed with an outlet for injecting the lubricating oil downward, that is, toward the motor and speed reducer. In addition, an oil pump is provided for pumping lubricating oil from an oil tank provided at the bottom of the casing, and an oil passage communicates with the discharge port of the oil pump. ing. Therefore, in the device described in Patent Document 1, by driving the oil pump to pump up the lubricating oil, the lubricating oil is jetted downward from the outflow port of the oil pipe, and the lubricating oil is delivered to the motor and the speed reducer. As it falls, the motor and speed reducer are cooled by the lubricating oil. Also, the lubricating oil whose temperature has risen by drawing heat from the motor and the reduction section flows down and is stored in the oil tank, or is pumped up again by the oil pump.

JP 2018-34713 A

The oil pipe in the device described in Patent Document 1 is arranged inside the motor casing above the motor section and the reduction section in parallel with the rotation center axis of the motor, and the outflow hole for flowing out the lubricating oil is downward. It is provided so that lubricating oil may flow out toward it. Therefore, since the lubricating oil flows out toward the motor portion and the speed reducing portion, the lubricating oil can be reliably supplied to the motor portion and the speed reducing portion. However, in the motor section and the reduction section, heat is generated not only in the upper portion but also in almost the entirety of the motor portion and the speed reduction portion. For example, the lower part than the upper part where the lubricating oil is supplied from the oil pipe is cooled by the lubricating oil flowing down along the motor part and the reduction part, but the lubricating oil flowing down along the motor part and the reduction part Since the temperature is high at the lower part, there is a possibility that the cooling of the lower part is insufficient.

In addition, since the lubricating oil that has flowed down to the oil tank is pumped up again by the oil pump and supplied to the motor section and the reduction section, the temperature of the lubricating oil gradually rises by taking heat from the motor section and the reduction section. In the device described in Patent Document 1, even if heat is radiated from the outer surface of the oil tank and the lubricating oil is cooled, not only is the surface area of the oil tank small, but the lubricating oil is stored in the oil tank. Since the oil is stored inside and does not flow, heat transfer to the oil tank and heat dissipation from the oil tank do not occur positively. That is, even if the lubricating oil absorbs heat from the motor section and the reduction section and cools them, the heat is not sufficiently dissipated from the lubricating oil to the outside. The overall temperature may rise.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a cooling device for an in-wheel motor that can improve cooling performance by promoting heat radiation to the outside air. is.

In order to achieve the above object, the present invention provides an in-house assembly that houses a motor for driving the wheel hub and a pump for pressurizing lubricating oil inside a housing that rotatably supports the wheel hub. In the wheel motor cooling device, a cooling pipe for injecting the lubricating oil sent under pressure from the pump is disposed in the upper part of the inside of the housing, and the cooling pipe is parallel to the rotation center axis of the motor. and a second pipe portion arranged in a direction crossing the first pipe portion and communicating with the first pipe portion, wherein the The first pipe portion is provided with a discharge hole for discharging the lubricating oil downward or in the circumferential direction of the motor. It is characterized in that another discharge hole for discharging is provided.

In the present invention, the cooling pipe for discharging the lubricating oil inside the housing is composed of the first pipe portion and the second pipe portion, and the direction of the lubricating oil discharged from these pipe portions is the axial direction or the circular direction. It becomes various directions, such as the circumferential direction. In other words, the locations where lubricating oil is supplied from the cooling pipe to the members or locations that generate heat, such as motors, are diversified. Efficient cooling is possible. Further, since the direction of discharge of the lubricating oil is varied, part of the lubricating oil adheres to the inner surface of the housing, and the lubricating oil can be cooled by dissipating heat from the lubricating oil to the outside air through the housing. can. That is, in the present invention, the cooling of the motor or the like by the lubricating oil and the cooling of the lubricating oil by the heat radiation from the lubricating oil can occur simultaneously. Cooling efficiency can be improved.

It is a sectional view showing one embodiment of the present invention. It is a typical perspective view showing an example of the cooling pipe. FIG. 4 is a cross-sectional view conceptually showing another example of the present invention; FIG. 4 is a cross-sectional view conceptually showing still another example of the present invention;

An embodiment of the present invention will now be described with reference to the drawings. It should be noted that the embodiment described below is merely an example of implementing the present invention, and does not limit the present invention.

FIG. 1 is a sectional view showing an example of an in-wheel motor IWM to which the present invention is applied. In the in-wheel motor IWM shown here, a wheel hub (hereinafter referred to as a hub) 2 to which a wheel 1 is attached and a motor 3 for driving the hub 2 (wheel 1) are housed inside a housing (casing) 4. It is This housing 4 is attached to the vehicle body by a suspension mechanism (not shown).

The housing 4 is roughly divided into a motor case 41 and a hub case 42 . The hub case 42 rotatably supports the hub 2 and the axle shaft 5 integrated therewith. With the hub 2 protruding outside, the hub 2 and the axle shaft 5 are rotatable by the bearings 6 . Support. A driven gear 7 is attached to the end of the axle shaft 5 opposite to the hub 2 side. A drive gear 8 meshes with the driven gear 7 . The driven gear 7 and the drive gear 8 constitute a reduction mechanism 9 , and the driven gear 7 has a larger diameter than the drive gear 8 .

The hub case 42 is open on the side opposite to the hub 2, while the motor case 41 is open on the hub case 42 side. attached to the The drive gear 8 that constitutes the speed reduction mechanism 9 is arranged across the boundary between the hub case 42 and the motor case 41 and across the cases 41, 42. is supported by the hub case 42 via the , and the intermediate portion is supported by the motor case 41 via the bearing 10b.

The motor case 41 is a nearly circular hollow body having an internal volume sufficient to accommodate the motor 3, and is divided into two parts substantially at the center in the axial direction. The hub case 42 is attached to the split body 411 on the right side in FIG. 1, and an opening is formed in the substantially central portion of the split body 412 on the left side in FIG. A cover plate 11 is attached to close the opening.

The motor 3 is, for example, a permanent magnet type synchronous motor, and its rotation center axis is parallel to the rotation center axes of the hub 2 and the axle shaft 5 and coincides with the rotation center axis of the driven gear 7 on the same axis. It is arranged inside the motor case 41 as shown. The motor 3 is a so-called inner rotor type motor. An annular stator 13 having a coil 12 is fixed to a motor case 41, and a rotor 14 is concentrically formed with the stator 13 on the inner peripheral side of the stator 13. A permanent magnet (not shown) is attached to the outer periphery of the rotor 14 . The rotor shaft 15 is a hollow shaft in the illustrated example, and the above-described drive gear 8 is inserted into the interior of the rotor shaft 15 and spline-fitted. Boss portions 16a and 16b facing each other on the same axis are formed in each of the divided bodies 411 and 412 constituting the motor case 41, and the boss portions 16a and 16b are fitted to the inner peripheral sides of the respective boss portions 16a and 16b. A rotor shaft 15 is rotatably held by bearings 17a and 17b. Note that the bearing 10b supporting the intermediate portion of the drive gear 8 is fitted in the boss portion 16b formed in the divided body 411 on the right side in FIG.

Next, the mechanism for cooling the heat-generating parts such as the motor 3 and the bearings will be described. there is An oil pump 18 for pumping up the oil is fitted to the shaft of the drive gear 8 . The oil pump 18 is an oil pump such as a gear pump or a cycloid pump that is used in conventional vehicles. It is fitted to the inner peripheral portion of the boss portion 16b.

The oil pump 18 communicates with a suction line 19 for sucking oil and a discharge line 20 for sending oil to a predetermined location. These conduits 19 and 20 may be constructed by pipes attached to the motor case 41, but in the example shown in FIG. Alternatively, it is configured by a hollow portion such as a turning hole. The housing 4 is held so that the rotation center axis of the motor 3 is substantially horizontal in normal use, and the lower portion in such normal use is an oil pan 21 . The suction line 19 communicates with the oil pan 21 so that the oil pump 18 pumps up oil from the oil pan 21 .

The discharge pipe 20 extends upward from the oil pump 18 and opens into the motor case 41 at a location near the upper end of the motor 3 . A cooling pipe 22 connected to the opening of the discharge conduit 20 is arranged in the upper part of the motor case 41 . The cooling pipe 22 is arranged in a direction that communicates with a first pipe portion 22a that is substantially parallel to the rotation center axis of the motor 3 and intersects the first pipe portion 22a. and a second pipe portion 22b.

The first pipe portion 22a is a substantially straight pipe that is longer than the width (the length in the axial direction) of the motor 3, and the tip thereof extends close to the inner surface of the split body 412 on the left side in FIG. . On the other hand, the second pipe portion 22b is a pipe branched from the first pipe portion 22a and arranged to face the inner wall surface of the motor case 41. A second pipe portion 22b branched near the right end in FIG. 1 of the first pipe portion 22a and a second pipe portion branched at the tip of the first pipe portion 22a so as to face 22b are provided. These second pipe portions 22b may be curved according to the contour shape of the inner wall surfaces facing each other, as shown in FIG. 2(A), or may be curved as shown in FIG. 2(B). , it may be a straight pipe.

The first pipe portion 22a is mainly for supplying oil to the motor 3 located therebelow, and is formed with a plurality of discharge holes 23a for discharging the oil. In addition, although the direction of the discharge hole 23a is mainly downward, it is not limited to this. The second pipe portion 22 b is mainly for supplying oil to the inner wall surface of the motor case 41 , and the plurality of discharge holes 23 b for discharging the oil are directed toward the inner wall surface of the motor case 41 . is provided in The outer surface of the motor case 41 is provided with fins F for increasing the contact area with the outside air (that is, the heat radiation area).

In the in-wheel motor IWM described above, when the motor 3 is energized to drive the motor 3, the torque generated by the rotation of the rotor 14 is amplified by the speed reduction mechanism 9 and transmitted to the axle shaft 5 and the hub 2 (wheel 1). the vehicle runs. In this case, when the drive gear 8 that constitutes the speed reduction mechanism 9 rotates, the oil pump 18 attached to the outer periphery thereof is driven, so that oil is pumped up from the oil pan 21 . The oil pressurized by the oil pump 18 is sent to the discharge pipe 20 and the cooling pipe 22 connected thereto. Oil is discharged mainly toward the inner wall surface of the motor case 41 from the pipe portion 22b.

The oil discharged toward the motor 3 flows down along the stator 13, the rotor 14, bearings, etc., and in the meantime takes heat from the stator 13, etc. for cooling. In addition, lubrication is performed by forming an oil film on friction points such as bearings. The oil flows down to the oil pan 21. - 特許庁Since the oil pan 21 is a part of the motor case 41 and is exposed to the outside air, the oil stored here is cooled by the outside air via the oil pan 21 . Moreover, it is again pumped up by the oil pump 18 and used for cooling and lubrication.

On the other hand, the oil discharged from the second pipe portion 22b toward the inner wall surface of the motor case 41 flows down along the inner wall surface. Since the motor case 41 is arranged near the wheel 1 and exposed to the outside air, its surface and the fins F serve as heat radiation surfaces. Therefore, since the temperature of the oil adhering to the inner wall surface is higher than that of the outside air, the oil dissipates heat through the motor case 41 and is cooled. In the process of flowing down the oil pan 21 along the inner wall surface, the oil comes into contact with the bearings and the like to perform lubrication and cooling.

Thus, according to the cooling device described above, the temperature of the oil enclosed inside the housing 4 is increased by cooling the motor 3 and lubricating and cooling the sliding parts such as the bearings. The oil is pumped up to the upper part of the motor case 41 by the oil pump 18 and sprayed inside the motor case 41 . also supplied to Since the motor case 41 itself is exposed to the outside air and is so-called air-cooled, the oil adhering to the inner wall surface of the motor case 41 radiates heat to the outside air via the motor case 41 and is cooled. That is, according to the cooling device of the present invention, by pumping up the oil and spraying it from the upper portion of the motor case 41, the oil itself can be cooled as well as the heat-generating portions such as the motor 3 are cooled by the oil. , the entire in-wheel motor IWM can be efficiently cooled.

The cooling device according to the present invention has the oil pump 18 because it is necessary to pump a predetermined amount of oil to the upper part of the motor case 41 . Since the oil pump 18 only needs to be driven by some kind of power, instead of being provided on the outer peripheral side of the shaft portion of the drive gear 8 described above, for example, as shown in FIG. may be configured to be driven by 3, the oil pump 18 is arranged concentrically with the axle shaft 5 at the rear end of the axle shaft 5, and its inner rotor is fitted to the axle shaft 5, while its outer rotor constitutes a motor case 41. It is fitted to the inner peripheral side of the boss portion for bearing formed in the divided body 411 that is connected to the bearing. Other configurations are the same as those shown in FIG. Therefore, when the wheel rotates, the oil pump 18 is driven to pump up oil from the oil pan 21 and supply it to the upper inner wall surfaces of the motor 3 and the motor case 41 .

Also, if necessary, the oil pump may be driven to cool the oil, an example of which is shown in FIG. That is, the example shown in FIG. 4 is an example in which the electric oil pump 181 is provided inside the housing 4 . In FIG. 4, an electric oil pump 181 is accommodated at a location near the oil pan 21, the suction port of which communicates with the aforementioned suction pipe line 19, and the discharge port of which communicates with the aforementioned discharge pipe line 20. . The electric oil pump 181 is connected to a power source (not shown) and to a controller (not shown) that controls on/off and rotation speed. 181 is configured to be driven to pump oil.

In addition, in the example shown in FIG. 4 , the speed reduction mechanism 9 is configured by a planetary gear mechanism 91 . The planetary gear mechanism 91 is arranged on the same axis as the rotor shaft 15, and the sun gear shaft 92 integrated with the sun gear 91s is fitted to the rotor shaft 15 to be integrated. The planetary gear mechanism 91 is accommodated inside the hub case 42 , and a ring gear 91 r arranged concentrically with the sun gear 91 s is fixed to the inner peripheral portion of the hub case 42 . A plurality of pinion gears 91p meshing with the sun gear 91s and ring gear 91r are held by a carrier 91c so as to rotate and revolve, and the carrier 91c is connected to the hub 2 (or an axle shaft integrated therewith). Therefore, the carrier 91c (i.e. hub 2), which is an output element, changes the rotation speed of the sun gear 91s (i.e., motor 3) which is an input element to the gear ratio of the planetary gear mechanism 91 (the number of teeth of the sun gear 91s and the number of teeth of the ring gear 91r). ratio). Other configurations are the same as those shown in FIG.

If the speed reduction mechanism 9 is configured as shown in FIG. 4, the rotor 14, the rotor shaft 15, the speed reduction mechanism 9, and the hub 2 can be arranged side by side on the same axis, which makes it easier to create a space on the oil pan 21 side. The electric oil pump 181 can be arranged in that space. Therefore, in the configuration shown in FIG. 4, the oil can be pumped up and cooled only when necessary, so that the electric oil pump 181 is not excessively driven, thereby improving energy efficiency (or electricity consumption). In addition, since the space can be secured and effectively used, the overall configuration of the cooling device or the in-wheel motor can be reduced in size and weight.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and the shape and position of the cooling pipe that discharges the oil can be appropriately changed according to the shape of the target housing. You can

1 wheel 2 hub 3 motor 4 housing
5 axle shaft 9 speed reduction mechanism 18 oil pump 19 suction pipe 20 discharge pipe 21 oil pan 22 cooling pipe 22a first pipe portion 22b second pipe portion 23a discharge hole 23b discharge hole 41 motor case 42 hub case 181 electric oil pump F fin IWM in-wheel motor

Claims (1)

A cooling device for an in-wheel motor, wherein a motor for driving the wheel hub and a pump for pressurizing lubricating oil are housed inside a housing that rotatably supports the wheel hub,
A cooling pipe for injecting the lubricating oil sent under pressure from the pump is arranged in the upper part of the inside of the housing,
The cooling pipe includes a first pipe portion arranged in a direction parallel to the rotation center axis of the motor, and a cooling pipe arranged in a direction crossing the first pipe portion and communicating with the first pipe portion. and a second pipe portion that
The first pipe portion is provided with a discharge hole for discharging the lubricating oil downward or in the circumferential direction of the motor, and the second pipe portion is provided with a discharge hole for discharging the lubricating oil along the axis of rotation. A cooling device for an in-wheel motor, characterized in that it is provided with another discharge hole for discharging in a direction.

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