Rotor shaft and motor assembly

Abstract

The present invention provides a rotor shaft and a motor assembly. The interior of the rotor shaft is a hollow cavity, and the output shaft (FO) of the motor coaxially passes through the rotor shaft from the hollow cavity. The hollow cavity includes a liquid inlet section (10), a liquid storage section (20), and a liquid outlet section (30). The liquid storage section (20) is located in the middle region of the rotor (R) in the axial direction. The rotor shaft further includes a first end liquid outlet hole (60) and a second end liquid outlet hole (70) that communicate the hollow cavity with the external space of the rotor shaft. The coolant can flow into the hollow cavity from the liquid inlet section (10), and then part of it flows out from the first end liquid outlet hole (60), part of it flows to the liquid storage section (20) and the liquid outlet section (30), and finally flows out from the second end liquid outlet hole (70). The rotor shaft according to the present application can guide the coolant to each cooling area with a reasonable flow distribution, providing good cooling for the motor assembly with the input and output shafts coaxially arranged. The motor assembly according to the present application has a simple and compact structure and good cooling effect.

Description

Technical Field

[0001] The present invention relates to the field of motors, and more particularly to a rotor shaft and a motor assembly. Background Art

[0002] Taking the motor of a new energy vehicle as an example, a large amount of heat is generated during the high-speed rotation of the motor. If the motor is not cooled in time, the motor efficiency will decrease or even malfunction.

[0003] For a rotor with a coaxial input shaft and output shaft, how to effectively guide the cooling oil flow to the vicinity of the rotor and reasonably distribute the coolant so that the rotor can be effectively cooled is an urgent problem to be solved in this field. Summary of the Invention

[0004] The purpose of the present invention is to overcome or at least mitigate the deficiencies of the above-mentioned prior art, and to provide a rotor shaft and a motor assembly with good cooling effect.

[0005] According to a first aspect of the present invention, there is provided a rotor shaft for non-rotatably connecting to a rotor of a motor.

[0006] The interior of the rotor shaft is a hollow cavity, and the output shaft of the motor can coaxially pass through the rotor shaft from the hollow cavity.

[0007] The hollow cavity includes a liquid inlet section, a liquid storage section, and a liquid outlet section. The inner diameters of the liquid inlet section, the liquid storage section, and the liquid outlet section are all larger than the outer diameter of the output shaft.

[0008] When the rotor shaft is assembled with the rotor, the liquid storage section is located in the middle region of the rotor shaft in the axial direction.

[0009] The rotor shaft further includes a first end liquid outlet hole and a second end liquid outlet hole that communicate the hollow cavity with the external space of the rotor shaft.

[0010] Coolant can flow into the hollow cavity from the liquid inlet section, and then part of it flows out from the first end liquid outlet hole, part of it flows to the liquid storage section and the liquid outlet section, and finally flows out from the second end liquid outlet hole.

[0011] In at least one embodiment, the inner diameter of the liquid inlet section is smaller than the inner diameter of the liquid storage section.

[0012] The hollow cavity further includes a first diameter-changing section that connects the liquid inlet section and the liquid storage section.

[0013] In at least one embodiment, the opening of the first end liquid outlet hole located in the hollow cavity is provided in the first diameter-changing section.

[0014] In at least one embodiment, the axial position of the first end liquid outlet hole on the first reduced-diameter section satisfies that 15% - 25% of the coolant flowing through the first reduced-diameter section flows out from the first end liquid outlet hole, and the remaining 85% - 75% flows into the liquid storage section.

[0015] In at least one embodiment, the inner diameter of the liquid outlet section is smaller than the inner diameter of the liquid storage section.

[0016] In at least one embodiment, the opening of the second end liquid outlet hole located in the hollow cavity is arranged in the liquid outlet section.

[0017] In at least one embodiment, the inner diameter of the liquid outlet section is larger than the inner diameter of the liquid inlet section.

[0018] In at least one embodiment, the first end liquid outlet hole includes a first end liquid outlet hole small section and a first end liquid outlet hole large section. In the radial direction of the rotor shaft, the first end liquid outlet hole small section is closer to the hollow cavity than the first end liquid outlet hole large section, and / or

[0019] The second end liquid outlet hole includes a second end liquid outlet hole small section and a second end liquid outlet hole large section. In the radial direction of the rotor shaft, the second end liquid outlet hole small section is closer to the hollow cavity than the second end liquid outlet hole large section.

[0020] According to a second aspect of the present application, there is provided an electric motor assembly, including a stator, a rotor, a rotor shaft and an output shaft. The rotor is arranged on the inner circumferential side of the stator. The rotor shaft is non-rotatably connected to the rotor. The output shaft can rotatably pass through the rotor shaft from inside the rotor shaft. Among them,

[0021] The rotor shaft is the rotor shaft according to the first aspect of the present application.

[0022] In at least one embodiment, in the axial direction of the rotor, the liquid storage section of the rotor shaft covers more than 90% of the axial region of the rotor, and the coolant flowing out from the first end liquid outlet hole and the second end liquid outlet hole of the rotor shaft can be sprayed to the two axial ends of the rotor.

[0023] The rotor shaft according to the present application can guide the coolant to each cooling area with a reasonable flow distribution, providing good cooling for the electric motor assembly with coaxial input and output shafts. The electric motor assembly according to the present application has a simple and compact structure and good cooling effect. Description of the Drawings

[0024] Figure 1 is a schematic structural diagram of the main components of an electric motor assembly according to an embodiment of the present application.

[0025] Figure 2 isFigure 1 Axial sectional view.

[0026] Figure 3 is Figure 1 sectional view.

[0027] Figure 4 is a schematic structural view of a rotor shaft according to an embodiment of the present application.

[0028] Figure 5 is Figure 4 axial sectional view.

[0029] Description of reference numerals:

[0030] S stator; R rotor; FO output shaft;

[0031] C1 first end cover; C2 second end cover; C20 liquid inlet channel;

[0032] FR rotor shaft; 10 liquid inlet section; 20 liquid storage section; 30 liquid outlet section; 40 first diameter-changing section; 50 second diameter-changing section; 60 first end liquid outlet hole; 61 small section of the first end liquid outlet hole; 62 large section of the first end liquid outlet hole; 70 second end liquid outlet hole; 71 small section of the second end liquid outlet hole; 72 large section of the second end liquid outlet hole; 80 closed section;

[0033] s1 first sealing device; s2 second sealing device. Detailed implementation manners

[0034] The exemplary embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that these specific descriptions are only used to teach those skilled in the art how to implement the present invention, and are not used to exhaust all feasible ways of the present invention, nor to limit the scope of the present invention.

[0035] Refer to Figures 1 to 5 , and introduce a motor assembly and its rotor shaft FR according to an embodiment of the present application. Unless otherwise specified, the radial direction, axial direction, and circumferential direction referred to below are all referenced with respect to the radial direction, axial direction, and circumferential direction of the rotor shaft FR.

[0036] The motor assembly of this embodiment includes a stator S, a rotor R, a rotor shaft FR, an output shaft FO, and a housing. The rotor R is disposed on the inner circumference of the stator S. The rotor shaft FR passes through the rotor R and is non-rotatably connected to the rotor R. The rotor shaft FR is a hollow shaft. The output shaft FO passes through the rotor shaft FR, is coaxial with the rotor shaft FR, and is rotatably connected to the rotor shaft FR. The two are connected via a transmission, and the transmission is not shown in the figure.

[0037] To facilitate the display of the internal structure of the motor assembly, only the end cover part of the housing is shown in the figure, including the first end cover C1 and the second end cover C2. The first end cover C1 is arranged at one axial end of the stator S and the rotor R, and the first end cover C1 provides support for the rotor shaft FR through the first bearing B1. The second end cover C2 is arranged on the axial side of the first end cover C1 away from the stator and the rotor, and the second end cover C2 provides support for the output shaft FO through the second bearing B2. A liquid inlet channel C20 is provided in the second end cover C2 for introducing coolant (such as engine oil from the transmission) into the motor interior.

[0038] Next, the coolant flow path inside the motor will be introduced in detail. The main structure of this coolant flow path relies on the rotor shaft FR.

[0039] The hollow cavity inside the rotor shaft FR can be divided into 6 sections according to different inner diameter sizes. Along the flowing direction of the coolant in the axial direction of the rotor shaft FR, these 6 sections are in sequence: the liquid inlet section 10, the first diameter-changing section 40, the liquid storage section 20, the second diameter-changing section 50, the liquid outlet section 30, and the closed section 80. The inner diameters of the liquid inlet section 10, the liquid storage section 20, the liquid outlet section 30, and the closed section 80 in different axial regions are equal respectively. Arranged in the order of decreasing inner diameter, they are in sequence: the liquid storage section 20, the liquid outlet section 30, the liquid inlet section 10, and the closed section 80, and their inner diameters are all larger than the outer diameter of the output shaft FO. Among them, the inner diameter of the closed section 80 is slightly larger than the outer diameter of the output shaft FO in a degree that is very close to the outer diameter of the output shaft FO, so that the rotor shaft FR and the output shaft FO do not contact, but basically no coolant flows through the closed section 80. It can be understood that since the closed section 80 finally opens to the transmission, even if a small amount of coolant flows out through the closed section 80, it is allowed; in addition, in some possible cases, it is also allowed for the coolant to flow into the inside of the rotor shaft FR from the transmission through the closed section 80.

[0040] The first diameter-changing section 40 connects the liquid inlet section 10 and the liquid storage section 20. Along the axial direction from the side where the liquid inlet section 10 is located to the side where the liquid storage section 20 is located, the inner diameter of the first diameter-changing section 40 gradually increases; the second diameter-changing section 50 connects the liquid outlet section 30 and the liquid storage section 20. Along the axial direction from the side where the liquid storage section 20 is located to the side where the liquid outlet section 30 is located, the inner diameter of the second diameter-changing section 50 gradually decreases.

[0041] One end of the liquid inlet section 10 is communicated with the liquid inlet channel C20, so that the coolant can be conducted into the hollow cavity inside the rotor shaft FR through the liquid inlet channel C20. Annular first sealing device s1 and second sealing device s2 are arranged at axial intervals in the connection area between the liquid inlet section 10 and the liquid inlet channel C20. The first sealing device s1 is arranged between the second end cover C2 and the output shaft FO, and the second sealing device s2 is arranged between the second end cover C2 and the rotor shaft FR.

[0042] Since the liquid storage section 20 is the section with the largest inner diameter in the hollow cavity, it also means that the hydraulic pressure of this section is relatively the smallest, which makes it easy for the coolant to accumulate in the liquid storage section 20. It should be understood that during the operation of the motor, the coolant is flowing and circulating, so the "accumulation" mentioned here is a dynamic process, which does not mean that the coolant in the liquid storage section 20 remains stationary, but the coolant in the liquid storage section 20 is constantly flowing toward the liquid outlet section 30; "accumulation" means that at any moment in the operation of the motor, the liquid storage section 20 is roughly filled or nearly filled with coolant, rather than only a small amount of coolant attached to the area such as the inner circumferential wall close to the rotor shaft FR (because the coolant rotates with the rotor shaft FR and is subjected to centrifugal force, it is possible that the coolant in the liquid storage section 20 is scarce when the hollow cavity structure is not designed properly). The coolant in the liquid storage section 20 can be dynamically accumulated in large quantities, so that the heat exchange capacity of the liquid storage section 20 is strong. In this embodiment, the liquid storage section 20 is located in the axial center of the rotor R, and the liquid storage section 20 covers more than 90% of the axial area of ​​the rotor R, so that the main body of the rotor R can exchange heat with the coolant in the liquid storage section 20 through heat conduction, and the heat dissipation effect of the rotor R is good.

[0043] Since the inner diameter of the liquid outlet section 30 is larger than that of the liquid inlet section 10 , the hydraulic pressure in the liquid outlet section 30 is relatively smaller than that in the liquid inlet section 10 , making it easier for the coolant to flow from the liquid inlet section 10 to the liquid outlet section 30 .

[0044] The rotor shaft FR forms a plurality of (four in this embodiment) second end liquid outlet holes 70 on the peripheral wall of the axial region where the liquid outlet section 30 is located, and the second end liquid outlet holes 70 are connected in the radial direction of the rotor shaft FR. The second end liquid outlet holes 70 are located in the region close to the axial end of the rotor R in the axial direction. Since the closed section 80 hardly allows the coolant to pass through, the coolant flowing to the liquid outlet section 30 will eventually be ejected from the second end liquid outlet hole 70 to the end of the rotor R, thereby cooling the end of the rotor R in a direct contact manner; in addition, this part of the coolant can also be ejected to the end of the stator S along the ejection path, thereby achieving the purpose of cooling the stator S.

[0045] The minimum inner diameter of the second end liquid outlet hole 70 is very small, for example, 2 mm, so as to form an outflowing water flow with a certain impact force. For the convenience of drilling process, the second end liquid outlet hole 70 is divided into two sections, a second end liquid outlet hole small section 71 and a second end liquid outlet hole large section 72, and the second end liquid outlet hole large section 72 is closer to the outer periphery of the rotor shaft FR. Therefore, when drilling, the second end liquid outlet hole large section 72 can be first drilled from the outer periphery of the rotor shaft FR (easier to achieve), and then the second end liquid outlet hole small section 71 can be drilled from the remaining thinner peripheral wall on the inner side.

[0046] The rotor shaft FR forms a plurality of (4 in this embodiment) first end liquid outlet holes 60 on the peripheral wall of the axial region where the first diameter-changing section 40 is located. The first end liquid outlet holes 60 communicate radially in the rotor shaft FR. The first end liquid outlet holes 60 are axially located in the region of the rotor R near the other axial end.

[0047] During the process of the coolant flowing from the liquid inlet section 10 to the liquid storage section 20, a small part of the coolant will be ejected from the first end liquid outlet holes 60 and shoot to the end of the rotor R to cool the end of the rotor R in a direct contact manner. Similarly, this part of the coolant can also shoot to the end of the stator S along the ejection path to achieve the purpose of cooling the stator S.

[0048] Since along the flow direction of the coolant, the inner wall of the first diameter-changing section 40 of the rotor shaft FR expands in a frustum shape towards the radially outer side, the coolant has a tendency to flow towards the radially outer side while flowing along the inner wall in this section under the action of centrifugal force. By means of this tendency brought by the centrifugal force, it can promote part of the coolant to flow through the first end liquid outlet holes 60 instead of all flowing to the liquid storage section 20.

[0049] It should be understood that the coolant flowing out from the first end liquid outlet holes 60 only accounts for a small part of the flowing coolant. Preferably, for example, 15% - 25% of the coolant flowing through the first diameter-changing section 40 flows out from the first end liquid outlet holes 60, and the remaining 85% - 75% further flows into the liquid storage section 20. The specific proportion of the coolant flowing out from the first end liquid outlet holes 60 can be adaptively designed according to the requirements of the motor design. By changing the position of the first end liquid outlet holes 60 in the first diameter-changing section 40, and / or changing the opening size of the first end liquid outlet holes 60, and / or changing the number of the first end liquid outlet holes 60, the proportion of the coolant flowing out from the first end liquid outlet holes 60 can be changed.

[0050] The first end liquid outlet holes 60 are also divided into two sections, the first end liquid outlet small section 61 and the first end liquid outlet large section 62, and the first end liquid outlet large section 62 is closer to the outer periphery of the rotor shaft FR.

[0051] In addition to facilitating the drilling process, the structure of the first end liquid outlet holes 60 with a small inner and large outer (smaller on the inner side close to the hollow cavity and larger on the outer side close to the outer space of the shaft) is also beneficial to controlling the amount of coolant flowing out, so that the coolant will not be ejected too much through the first end liquid outlet holes 60. It is worth noting that although the second end liquid outlet holes 70 introduced above have a similar structure, they are not used to limit the amount of coolant flowing out, because as the end of the flow channel, almost all the coolant flowing to the liquid outlet section 30 will be ejected from the second end liquid outlet holes 70.

[0052] Figure 3The thick arrows therein schematically show the flow path of the coolant within the motor assembly. In summary, the coolant flowing through the rotor shaft SR can supply coolant to three regions of the rotor: (1) cooling the axial first ends of the rotor R and the stator S through the first end liquid outlet holes 60, (2) cooling the axial second ends of the rotor R and the stator S through the second end liquid outlet holes 70, and (3) cooling the main body portion of the rotor R through the dynamic accumulation in the liquid storage section 20.

[0053] It should be understood that the above embodiments and some of their aspects or features can be appropriately combined.

[0054] The present invention has at least one of the following advantages:

[0055] (i) Through the reasonable arrangement of the cavity within the rotor shaft FR (including the partitioned sections of the cavity and the axial position of the cavity relative to the rotor R), the main body region of the rotor of the motor assembly with the input and output shafts coaxially arranged, as well as the ends of the rotor and the stator, can obtain good cooling.

[0056] (ii) By reasonably setting the liquid inlet section 10, the first diameter-changing section 40, the liquid storage section 20, the second diameter-changing section 50, and the liquid outlet section 30, the coolant can flow smoothly along the preset direction instead of statically accumulating in certain regions, and the overall cooling effect of the motor assembly is good.

[0057] Certainly, the present invention is not limited to the above embodiments, and those skilled in the art can make various modifications to the above embodiments of the present invention under the teaching of the present invention without departing from the scope of the present invention.

Claims

1. A rotor shaft, used to be connected to a rotor (R) of a motor in a non-rotatable manner, characterized in that: The interior of the rotor shaft is a hollow cavity, and the output shaft (FO) of the motor can coaxially pass through the rotor shaft from the hollow cavity. The hollow cavity comprises a liquid inlet section (10), a liquid storage section (20) and a liquid outlet section (30); the inner diameters of the liquid inlet section (10), the liquid storage section (20) and the liquid outlet section (30) are all larger than the outer diameter of the output shaft (FO); the inner diameter of the liquid outlet section (30) is smaller than the inner diameter of the liquid storage section (20); When the rotor shaft and the rotor (R) are assembled, the liquid storage section (20) is located in the middle area of ​​the rotor (R) in the axial direction. The rotor shaft further comprises a first end liquid outlet hole (60) and a second end liquid outlet hole (70) communicating with the hollow cavity and the external space of the rotor shaft. The cooling liquid can flow into the hollow cavity from the liquid inlet section (10), then partially flow out from the first end liquid outlet hole (60), partially flow to the liquid storage section (20) and the liquid outlet section (30), and finally flow out from the second end liquid outlet hole (70). The inner diameter of the liquid inlet section (10) is smaller than the inner diameter of the liquid storage section (20). The hollow cavity further comprises a first diameter-reducing section (40), the first diameter-reducing section (40) connecting the liquid inlet section (10) and the liquid storage section (20), the rotor shaft expanding radially outward in a frustum shape on the inner wall of the first diameter-reducing section (40), and the opening of the first end liquid outlet hole (60) located in the hollow cavity is arranged in the first diameter-reducing section (40).

2. The rotor shaft according to claim 1, characterized in that The axial position of the first end liquid outlet hole (60) on the first diameter-changing section (40) satisfies the condition that 15% to 25% of the cooling liquid flowing through the first diameter-changing section (40) flows out from the first end liquid outlet hole (60), and the remaining 85% to 75% flows into the liquid storage section (20).

3. The rotor shaft according to claim 1, characterized in that The opening of the second end liquid outlet hole (70) located in the hollow cavity is arranged in the liquid outlet section (30).

4. The rotor shaft according to claim 1, characterized in that The inner diameter of the liquid outlet section (30) is greater than the inner diameter of the liquid inlet section (10).

5. The rotor shaft according to claim 1, characterized in that The first end liquid outlet hole (60) comprises a first end liquid outlet hole small section (61) and a first end liquid outlet hole large section (62); in the radial direction of the rotor shaft, the first end liquid outlet hole small section (61) is closer to the hollow cavity than the first end liquid outlet hole large section (62); and / or The second end liquid outlet hole (70) comprises a second end liquid outlet hole small section (71) and a second end liquid outlet hole large section (72); in the radial direction of the rotor shaft, the second end liquid outlet hole small section (71) is closer to the hollow cavity than the second end liquid outlet hole large section (72).

6. A motor assembly, comprising a stator (S), a rotor (R), a rotor shaft (FR) and an output shaft (FO), wherein the rotor (R) is arranged on the inner circumference of the stator (S), the rotor shaft (FR) is connected to the rotor (R) in a non-rotatable manner, and the output shaft (FO) can pass through the inside of the rotor shaft (FR) in a rotatable manner relative to the rotor shaft (FR), characterized in that: The rotor shaft (FR) is a rotor shaft according to any one of claims 1 to 5.

7. The motor assembly according to claim 6, characterized in that: In the axial direction of the rotor (R), the liquid storage section (20) of the rotor shaft (FR) covers more than 90% of the axial area of ​​the rotor (R), and the coolant flowing out of the first end liquid outlet hole (60) and the second end liquid outlet hole (70) of the rotor shaft (FR) can be sprayed to the two axial ends of the rotor (R).

8. The motor assembly according to claim 6, characterized in that: The motor assembly further comprises a first end cover (C1) and a second end cover (C2), wherein the first end cover (C1) is arranged at an axial end of the stator (S) and the rotor (R), and the second end cover (C2) is arranged at an axial side of the first end cover (C1) away from the stator (S) and the rotor (R), and a liquid inlet channel (C20) is arranged in the second end cover (C2). A first sealing device (s1) and a second sealing device (s2) are arranged in an axially spaced relationship in the connection area between the liquid inlet section (10) and the liquid inlet channel (C20); the first sealing device (s1) is arranged between the second end cover (C2) and the output shaft (FO); and the second sealing device (s2) is arranged between the second end cover (C2) and the rotor shaft (FR).

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