Speed reduction mechanism-equipped motor

Abstract

This speed reduction mechanism-equipped motor GM comprises: a motor M that is housed within a motor housing 1; and a speed reduction mechanism 3 that is housed within a gear housing 2. The speed reduction mechanism 3 is composed of a hypoid gear and is equipped with a pinion P and a ring gear R. The motor housing 1 is equipped with a heat exchanger 5 that performs heat exchange between gear oil 6 introduced from the gear housing 2 side and a refrigerant for the motor. Between the gear housing 2 and the motor housing 1, an oil circulation path is disposed which allows the gear oil 6 introduced from the gear housing 2 side to pass through the heat exchanger 5 and to return to the gear housing 2. The speed reduction mechanism-equipped motor cools the reduction mechanism 3 that is prone to relatively high temperatures.

Description

Motor with reduction mechanism

[0001] The present invention relates to a motor with a speed reduction mechanism used as a drive source for an electric vehicle, for example.

[0002] A conventional motor with a speed reduction mechanism is described in Patent Document 1, which is titled "Drive unit for electric vehicles." The motor with a speed reduction mechanism described in Patent Document 1 includes a through shaft that transmits motor torque to a transmission gear, a pinion shaft that transmits the torque transmitted via the transmission gear to an axle, a drive pinion that rotates in response to rotation of the pinion shaft, and a ring gear that meshes with the drive pinion, and is configured to rotate the axle shaft by rotation of the ring gear.

[0003] Japanese Patent Application Publication No. 2022-61200

[0004] However, when the above-described conventional motor with a speed reduction mechanism is used in an electric vehicle, the speed reduction mechanism and the motor exchange heat with each other depending on the driving conditions, and there is a risk that the speed reduction mechanism side in particular will become too hot.

[0005] The present invention has been made in view of the above-mentioned conventional situation, and has as its object to provide a motor with a speed reduction mechanism that can cool the speed reduction mechanism, which tends to become relatively hot.

[0006] A motor with a reduction gear according to the present invention includes a motor housed in a motor housing and a reduction gear housed in a gear housing. The reduction gear comprises a hypoid gear and includes a pinion provided on the motor output shaft and a ring gear with which the pinion engages. The motor housing includes a heat exchanger that exchanges heat between gear oil introduced from the gear housing side and a motor coolant that cools the motor. The motor with a reduction gear includes an oil circulation path between the gear housing and the motor housing that passes gear oil introduced from the gear housing side through the heat exchanger and returns it to the gear housing.

[0007] The motor with a speed reduction mechanism according to the present invention employs the above-described configuration, making it possible to cool the speed reduction mechanism, which tends to become relatively hot.

[0008] Fig. 1 is a cross-sectional explanatory view showing one embodiment of a motor with a reduction gear mechanism according to the present invention; Fig. 2 is a cross-sectional explanatory view showing one spiral structure provided in an oil flow passage of an output shaft; Fig. 3 is a cross-sectional explanatory view schematically showing a heat exchanger; Fig. 4 is a perspective view schematically showing a heat exchanger; Fig. 5 is a plan view schematically showing the inside of a heat exchanger;

[0009] 1 includes a motor M housed in a motor housing 1 and a reduction mechanism 3 housed in a gear housing 2. The reduction mechanism 3 is made of a hypoid gear and includes a pinion P provided on an output shaft 4 of the motor M and a ring gear R with which the pinion P engages.

[0010] The illustrated motor GM with a speed reduction mechanism constitutes the drive source of the electric vehicle. The motor M is oriented with the axis of the output shaft 4 in a horizontal direction. The speed reduction mechanism 3 is oriented with the axis of the ring gear R in a horizontal direction perpendicular to the axis of the output shaft 4, and transmits the rotation of the motor M to an axle (not shown) via a differential mechanism D (part of which is shown).

[0011] In the motor GM with a reduction mechanism, the motor housing 1 is provided with a heat exchanger 5 that exchanges heat between gear oil introduced from the gear housing 2 side and a motor refrigerant that cools the motor M. Gear oil 6 is also stored in the gear housing 2. The motor GM with a reduction mechanism has an oil circulation path between the gear housing 2 and the motor housing 1 that passes the gear oil 6 introduced from the gear housing 2 side through the heat exchanger 5 and returns it to the gear housing 2.

[0012] The oil circulation path is provided within the gear housing 2 with a ring gear R, a catch tank 7 that collects gear oil 6 scooped up by the rotating ring gear R, and an oil flow passage 8 that is formed on the axis of the output shaft 4 and returns the gear oil 6 discharged from the heat exchanger 5 to the gear housing 2. Therefore, the heat exchanger 5 exchanges heat between the gear oil 6 introduced from the catch tank 7 and the motor refrigerant.

[0013] 2, the oil flow passage 8 of the output shaft 4 has a circular cross section, is open at both ends of the output shaft 4, and is provided with a helical structure 9 that transfers the gear oil 6 discharged from the heat exchanger 5 to the gear housing 2. This helical structure 9 is a so-called Archimedean screw, and is provided with a shaft 9A disposed at the center of the oil flow passage 8 and a helical plate 9B provided along the axial direction of this shaft 9A, and rotates together with the output shaft 4.

[0014] The heat exchanger 5 is disposed in at least one of the first and second quadrants centered on the output shaft 4 when viewed from the axial direction of the output shaft 4, and as shown schematically in Figures 3 and 4, has a plurality of oil flow paths F1 through which gear oil 6 flows along the axial direction of the output shaft 4, and a plurality of refrigerant flow paths F2 through which motor refrigerant flows also along the axial direction of the output shaft 4. The heat exchanger 5 has a structure in which the oil flow paths F1 and the refrigerant flow paths F2 are arranged alternately in parallel in the vertical direction. Note that Figure 4 shows the outlet side of the oil flow path F1 of the heat exchanger 5.

[0015] The oil flow path F1 and the refrigerant flow path F2 are separated from each other by a partition wall, and fins or the like may be placed on the partition wall to improve heat exchange efficiency. In practice, each of the housings 1 and 2 and the motor M may have fluid flow paths integrally formed therewith, such as a water jacket. The motor refrigerant is, for example, water or oil. In the heat exchanger 5, the gear oil 6 and the motor refrigerant may flow in opposite directions or in the same direction.

[0016] 5, the heat exchanger 5 has an uppermost oil flow path F1 that communicates with the catch tank 7 and a branch path Fb that intersects with the adjacent refrigerant flow path F2 and leads to the lower oil flow path F1. The heat exchanger 5 in the illustrated example has a branch path Fb in the middle of the uppermost oil flow path F1 that leads to the second oil flow path F1 from the top in FIG. 5, and the second oil flow path F1 has a branch path Fb downstream of the branch path Fb (to the right in FIG. 5) that leads to the third oil flow path F1.

[0017] The heat exchanger 5 described above can be manufactured using a three-dimensional modeling device (a so-called 3D printer) because the branch passage Fb has a multi-level intersection structure. In this case, the heat exchanger 5 may be molded as a whole, or each section divided in the thickness direction or into small parts may be molded separately and then assembled. Alternatively, the heat exchanger 5 may be molded as a whole by casting each section divided in the thickness direction or into small parts and then assembled.

[0018] As a result, the multiple oil flow paths F1 are structured such that they branch into multiple paths toward the downstream side. Furthermore, the oil flow paths F1 are structured such that their cross-sectional area increases toward the downstream side. That is, as shown in FIG. 5 , the oil flow path F1 has a width W2 at its downstream end that is larger than its width W1 at its upstream end, and the width gradually increases from the upstream end to the downstream end. This facilitates oil flow through the oil flow path F1, which can contribute to improved cooling performance. Furthermore, when the heat exchanger 5 is manufactured by casting, as described above, it is advantageous in that the mold forming the oil flow path F1 can be easily removed. The cross-sectional area of ​​the oil flow path F1 may change continuously as shown in the figure, or may change in stages.

[0019] As described above, the reduction gear motor GM having the above-described configuration reduces the rotation of the motor M by the reduction gear mechanism 3 and transmits it to the axle. At this time, the reduction gear motor M scoops up the gear oil 6 stored in the gear housing 2 with the tooth surface of the rotating ring gear R and collects it in the catch tank 7, as shown by the arrow in Figure 1.

[0020] The reduction gear motor GM also introduces the gear oil 6 collected in the catch tank 7 into the heat exchanger 5 via a path not shown. The heat exchanger 5 branches the gear oil 6 introduced into the uppermost oil flow path F1 into multiple paths downstream, and also circulates the motor refrigerant through the refrigerant flow path F2, thereby exchanging heat between the relatively high-temperature gear oil 6 and the relatively low-temperature motor refrigerant.

[0021] Furthermore, the reduction gear motor GM introduces the gear oil 6 discharged from the heat exchanger 5 through a path in the motor housing 1 into the oil flow passage 8 of the output shaft 4. At this time, the reduction gear motor GM transfers the introduced gear oil 6 to the pinion gear P side, i.e., the gear housing 2 side, by rotating a spiral structure 9 provided in the oil flow passage 8 together with the output shaft 4, and then discharges the gear oil 6 from the end of the output shaft 4 and returns it to the gear housing 2.

[0022] In this way, the motor GM with reduction mechanism continuously cools and circulates the gear oil 6 as described above while the motor M is rotating, thereby cooling the reduction mechanism 3, which tends to become relatively hot. Furthermore, since the motor GM with reduction mechanism employs a hypoid gear for the reduction mechanism 3, in addition to the cooling function described above, a reduction ratio equivalent to that of a helical gear can be obtained and it can also contribute to space saving.

[0023] Furthermore, since the motor GM with reduction mechanism has an oil circulation path formed by the ring gear R, catch tank 7, heat exchanger 5, and oil flow passage 8 of the output shaft 4, the gear oil 6 can be cooled and circulated without using auxiliary equipment such as an oil pump, thereby reducing the number of parts and manufacturing costs, and also cooling the output shaft 4.

[0024] Furthermore, since the motor GM with a reduction mechanism is equipped with a spiral structure 9 in the oil flow passage 8, the gear oil 6 can be smoothly transported by the rotation of the output shaft 4 without requiring any other power, thereby further improving the circulation function of the gear oil 6.

[0025] Furthermore, in the motor GM with a reduction mechanism, in the heat exchanger 5 located on the upper side of the motor housing 1, the gear oil 6 introduced from the catch tank 7 into the top oil flow path F1 falls naturally and branches into multiple paths downstream.

[0026] As a result, the motor GM with reduction mechanism can reduce the length dimension (dimension in the flow direction) of the heat exchanger 5, allowing for highly efficient heat exchange.In addition, since the only introduction point for the gear oil 6 from the catch tank 7 is the uppermost oil flow path F1, backflow of the gear oil 6 toward the reduction mechanism 3 can be prevented.

[0027] Furthermore, since the heat exchanger 5 has multiple oil flow paths F1 arranged along the axial direction of the output shaft 4, the gear oil 6 is easily collected at the end of the oil flow passage 8, i.e., the end opposite the pinion P, which can contribute to improving the circulation function of the gear oil 6.

[0028] Furthermore, in the motor GM with a reduction mechanism, the oil flow path F1 in the heat exchanger 5 has a structure in which the cross-sectional area increases toward the downstream side, which makes the flow of the gear oil 6 even smoother, thereby further improving the heat exchange rate with the motor refrigerant and the circulation function of the gear oil 6.

[0029] The configuration of the motor with a speed reduction mechanism according to the present invention is not limited to the above-described embodiment, and can be modified as appropriate within the scope of the present invention.

[0030] REFERENCE SIGNS LIST 1 Motor housing 2 Gear housing 3 Reduction mechanism 4 Output shaft 5 Heat exchanger (oil circulation path) 6 Gear oil 7 Catch tank (oil circulation path) 8 Oil flow path (oil circulation path) 9 Spiral structure F1 Oil flow path F2 Refrigerant flow path Fb Branch path GM Motor with reduction mechanism M Motor P Pinion R Ring gear

Claims

1. In a motor with a speed reduction mechanism including a motor housed in a motor housing and a speed reduction mechanism housed in a gear housing, the speed reduction mechanism consists of a hypoid gear and includes a pinion provided on an output shaft of the motor and a ring gear engaged with the pinion, the motor housing is provided with a heat exchanger that performs heat exchange between gear oil introduced from the gear housing side and a refrigerant for cooling the motor, A motor with a speed reduction mechanism is characterized in that there is an oil circulation path between the gear housing and the motor housing, through which the gear oil introduced from the gear housing side into the motor housing passes through the heat exchanger and returns into the gear housing.

2. The gear oil is stored in the gear housing, and the oil circulation path includes a catch tank that collects the gear oil scooped up by the rotating ring gear in the gear housing, and an oil flow passage formed on the axis of the output shaft and returning the gear oil discharged from the heat exchanger into the gear housing. The motor with a speed reduction mechanism according to claim 1, wherein the heat exchanger performs heat exchange between the gear oil introduced from the catch tank and the refrigerant for the motor.

3. The motor with a speed reduction mechanism according to claim 2, characterized in that a spiral structure for transferring the gear oil discharged from the heat exchanger to the gear housing side along with the rotation of the output shaft is provided in the oil flow passage.

4. The heat exchanger is arranged in at least one of the first quadrant and the second quadrant centered on the output shaft when viewed from the axial direction of the output shaft, A plurality of oil flow paths for flowing the gear oil along the axial direction of the output shaft, and a plurality of refrigerant flow paths for flowing the refrigerant for the motor along the axial direction of the output shaft, and having a structure in which the oil flow paths and the refrigerant flow paths are arranged in parallel alternately in the vertical direction, Among the plurality of oil flow paths, the uppermost oil flow path communicates with the catch tank, and is provided with a branch path that intersects the adjacent refrigerant flow path and leads to the lower oil flow path, The speed reduction mechanism-equipped motor according to claim 2, characterized in that the oil flow path has a structure that branches into a plurality in the downstream direction as a whole.

5. The speed reduction mechanism-equipped motor according to claim 5, characterized in that the oil flow path has a structure in which the cross-sectional area increases toward the downstream.