Motor cooling device
The motor cooling device improves cooling efficiency by using an offset collision wall and turn sections in the oil passage, addressing issues of pressure loss and magnetic interference.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- TOYOTA JIDOSHA KK
- Filing Date
- 2023-10-23
- Publication Date
- 2026-06-02
AI Technical Summary
Existing motor cooling devices lack effective means to enhance cooling performance while minimizing pressure loss, cost, and interference with magnetic fields.
A motor cooling device with an oil passage formed by overlapping oil holes in steel plates, featuring an offset collision wall and turn sections, which improves cooling efficiency through turbulent flow and reduced pressure loss.
The device achieves enhanced cooling performance with minimal pressure loss and cost, while reducing interference with magnetic fields and motor torque.
Smart Images
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Abstract
Description
Technical Field
[0001] The present disclosure relates to a motor cooling device.
Background Art
[0002] Patent Document 1 describes a motor cooling system in which an oil passage for introducing cooling oil is formed in the teeth of a stator. The oil passage has a certain shape in the direction in which the cooling oil flows.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] It is desired to improve the cooling performance of a motor cooling device.
[0005] The present disclosure has been made in view of the above, and an object thereof is to provide a motor cooling device capable of improving cooling performance.
Means for Solving the Problems
[0006] The motor cooling device according to the present disclosure is formed in a stator formed by laminating a plurality of steel plates, and is an oil passage serving as a conduit for cooling oil, and is formed by overlapping oil holes formed in the plurality of steel plates in the stacking direction, and the oil passage has an offset collision wall formed by overlapping while being displaced in a direction orthogonal to the stacking direction.
Effects of the Invention
[0007] According to the present disclosure, a motor cooling device capable of improving cooling performance can be realized.
Brief Description of the Drawings
[0008] [Figure 1] Figure 1 is a cross-sectional view showing a schematic configuration of the oil passages in the motor cooling device according to this embodiment. [Figure 2] Figure 2 is a diagram illustrating the steel plate of the motor cooling device shown in Figure 1. [Figure 3] Figure 3 shows the heat transfer coefficient of the oil passage. [Figure 4] Figure 4 shows the magnetic flux density of a steel plate. [Modes for carrying out the invention]
[0009] A motor cooling device according to the embodiments of this disclosure will be described with reference to the drawings. Note that the components in the following embodiments include those that are easily replaceable or substantially identical to those that are replaceable by a person skilled in the art.
[0010] (Embodiment) Figure 1 is a cross-sectional view showing a schematic configuration of the oil passages of a motor cooling device according to an embodiment. Figure 1 is a cross-sectional view of a stator S formed by laminating multiple steel plates, along the lamination direction D1 (left-right direction in Figure 1), and the up-down direction in Figure 1 corresponds to the radial direction D2 centered on the rotation axis of the rotor. As shown in Figure 1, the motor cooling device 1 includes an oil pan 2 for storing cooling oil, an oil pump 3 for outputting cooling oil at a predetermined hydraulic pressure, and oil passages 4 that serve as conduits for the cooling oil.
[0011] The motor cooling device 1 cools the motor by outputting cooling oil stored in the oil pan 2 at a predetermined hydraulic pressure using the oil pump 3, and circulating the cooling oil inside the oil passage 4 formed in the stator S.
[0012] Figure 2 is a diagram illustrating the steel plates of the motor cooling device shown in Figure 1. The stator S consists of multiple stacked steel plates P, but in Figure 2, only five steel plates P are shown to illustrate the configuration of the steel plates P. Furthermore, although the steel plates P form an annular shape centered on the rotor's axis of rotation, only a portion of the steel plates P, including one tooth T, is shown in Figure 2.
[0013] The steel plate P has three oil holes 411, 412, and 413 formed along the radial direction D2 from the inside to the outside. The oil holes 411, 412, and 413 are located such that the radial direction D2 is longer than the circumferential direction D3 which is perpendicular to the radial direction D2. The stator S has teeth T that protrude inward in the radial direction D2, and the outermost oil hole 413 in the radial direction D2 is formed outside the teeth T in the radial direction D2, while the other oil holes 411 and 412 are formed on the teeth T.
[0014] The oil passage 4 is formed by the overlapping of oil holes 411, 412, and 413 formed in multiple steel plates P in the stacking direction D1. Cooling oil 5 is introduced into the oil passage 4 in order from the oil hole 411 located on the inside in the radial direction D2. That is, the cooling oil 5 is introduced in the order of oil hole 411, oil hole 412, and oil hole 413.
[0015] Returning to Figure 1, the oil passage 4 has an offset collision wall 41 formed by the overlapping of oil holes 411, 412, and 413 with a shift in a direction perpendicular to the stacking direction D1. Figure 1 shows an example in which the offset collision wall 41 is formed by the overlapping of oil holes 411, 412, and 413 with a shift in the radial direction D2, but it is preferable that the offset collision wall 41 is formed by the overlapping of oil holes 411, 412, and 413 with a shift in the circumferential direction D3. The offset collision wall 41 is formed, for example, every 30 stacks of steel plates P, but the number is not particularly limited and can be set to any number of one or more plates.
[0016] Furthermore, the oil passage 4 has a turn section 42 that folds back in the stacking direction D1. The oil passage 4 has two turn sections 42, and the cooling oil 5 introduced from one end in the stacking direction D1 is discharged from the other end in the stacking direction D1.
[0017] In FIG. 2, the temperature is illustrated by the shading density of the hatch so that the hatch of the high temperature portion becomes lighter. By introducing the cooling oil 5 in order from the oil hole 411 located inside the radial direction D2 where the temperature of the steel plate P is high, the high temperature portion of the steel plate P can be efficiently cooled with the low temperature cooling oil 5.
[0018] FIG. 3 is a diagram showing the heat transfer coefficient of the oil passage. In FIG. 3, the heat transfer coefficient is illustrated by the shading density of the hatch so that the hatch of the portion with a high heat transfer coefficient becomes lighter. As shown in FIG. 3, the heat transfer coefficient becomes large in the vicinity of the offset collision wall 41. This is because the cooling oil 5 flowing through the oil passage 4 collides with the offset collision wall 41, generating a turbulent flow and disturbing the downstream flow, thereby improving the heat transfer coefficient between the cooling oil 5 and the wall surface of the stator S.
[0019] FIG. 4 is a diagram showing the magnetic flux density of the steel plate. In FIG. 4, the magnetic flux density is illustrated by the shading density of the hatch so that the hatch of the portion with a high magnetic flux density becomes lighter, and magnetic field lines are also illustrated. As shown in FIG. 4, it can be seen that there is no significant difference in the distribution of the magnetic flux density between the case where the oil holes 411, 412, and 413 are not formed in the steel plate P shown in (a) of FIG. 4 and the case where the oil holes 411, 412, and 413 are formed in the steel plate P shown in (b) of FIG. 4.
[0020] In addition, FIG. 4(c) shows a partially enlarged view of FIG. 4(b). The outermost oil hole 413 in the radial direction D2 is formed outside the radial direction D2 from the teeth T, and the oil holes 411 and 412 other than the oil hole 413 are formed in the teeth T. By adopting such a configuration, the change in the magnetic flux density due to the formation of the oil holes 411, 412, and 413 in the steel plate P can be reduced.
[0021] According to the motor cooling device 1 described above, since the oil passage 4 has the offset collision wall 41, even with a small flow rate, the cooling performance can be improved with a low pressure loss, and a small and low-cost motor cooling device 1 can be provided.
[0022] In addition, the offset collision wall 41 is formed by the oil holes 411, 412, and 413 being offset and overlapping in the circumferential direction D3. Specifically, the offset collision wall 41 can be formed by alternately laminating 30 sheets each of two types of steel plates P with different shapes. Therefore, an increase in the types of steel plates P with different shapes can be suppressed, and an increase in labor and cost can be suppressed. Note that by reversing one type of steel plate P and using it as a steel plate P with a different shape, an increase in the types of steel plates P with different shapes may be further suppressed.
[0023] In addition, the oil holes 411, 412, and 413 have a longer radial direction D2 than the circumferential direction D3, and the offset collision wall 41 is formed by the oil holes 411, 412, and 413 being offset and overlapping in the circumferential direction D3. As a result, the offset collision wall 41 is formed on the long sides of the oil holes 411, 412, and 413, and the area of the offset collision wall 41 can be increased. Therefore, the cooling performance can be improved and an increase in pressure loss can be suppressed.
[0024] In addition, three oil holes 411, 412, and 413 are formed in the steel plate P along the radial direction D2. As a result, the oil holes 411, 412, and 413 are arranged along the magnetic field lines of the teeth T, so an increase in magnetic resistance and a decrease in motor torque caused thereby can be suppressed.
[0025] In addition, the oil passage 4 has a turn portion 42 that turns back in the lamination direction D1. As a result, even if the cooling oil 5 has the same flow rate and flow velocity, the area of the wall surface of the oil passage 4 that the cooling oil 5 contacts can be increased, and the cooling performance can be improved. Furthermore, since turbulent flow also occurs in the turn portion 42, the heat transfer coefficient is improved and the cooling performance is improved.
[0026] In addition, the oil passage 4 discharges the cooling oil 5 introduced from one end in the lamination direction D1 from the other end in the lamination direction D1. As a result, since the inlet and outlet of the cooling oil 5 are located on opposite end faces, it does not interfere with the coil ends and can also prevent mutual interference.
[0027] Furthermore, cooling oil 5 is introduced into the oil passage 4 sequentially from the oil holes 411 located on the inside in the radial direction D2. As a result, the inner portion of the teeth T, where the temperature of the steel plate P is high, can be efficiently cooled with the cooling oil 5, which is at a lower temperature.
[0028] Furthermore, the outermost oil hole 413 in the radial direction D2 is formed outside the teeth T in the radial direction D2, while the other oil holes 411 and 412 are formed on the teeth T. As a result, a reduction in the magnetic path and the resulting decrease in motor torque can be suppressed.
[0029] Furthermore, an inlet-side coil end cooling oil hole may be formed in front of the inlet of the oil passage 4 to cool the coil end. This allows for cooling of the coil end and improves the insulation of the coil end.
[0030] Furthermore, an outlet-side coil end cooling oil hole may be formed after the outlet of the oil passage 4 to cool the coil end. This allows for cooling of the coil end and improves the insulation of the coil end.
[0031] Further effects and modifications can be readily derived by those skilled in the art. Therefore, broader aspects of the present invention are not limited to the specific details and representative embodiments expressed and described above. Accordingly, various modifications are possible without departing from the spirit or scope of the overall concept of the invention as defined by the appended claims and their equivalents. [Explanation of Symbols]
[0032] 1. Motor cooling device 2 oil pan 3. Oil pump 4 Oil road 5 Cooling oil 41 Offset collision wall 42 Turn section 411, 412, 413 oil hole P steel plate S stata T Teeth
Claims
1. An oil passage formed in a stator made by laminating multiple steel plates, each having multiple oil holes formed along the radial direction centered on the rotor's axis of rotation, which serves as a conduit for cooling oil, The oil holes formed in the plurality of steel plates are formed by overlapping in the stacking direction. The oil passage comprises an offset collision wall formed by the overlapping of the oil holes in a direction perpendicular to the stacking direction, The oil passage has a turn portion that folds back in the stacking direction, A motor cooling device in which the cooling oil is introduced into the oil passage from the oil hole located furthest in the radial direction, and each time it turns back at the turn section, the cooling oil is introduced into the oil hole adjacent to the radially outer side.
2. The oil hole is such that the radial direction is longer than the circumferential direction perpendicular to the radial direction. The motor cooling device according to claim 1, wherein the offset collision wall is formed by the oil holes overlapping with a circumferential offset.
3. The motor cooling device according to claim 2, wherein the stator includes steel plates having the same shape and stacked in reverse.
4. The steel plate has three oil holes formed along the radial direction. The motor cooling device according to claim 3, wherein the oil passage has two turns, and the cooling oil introduced from one end in the stacking direction is discharged from the other end in the stacking direction.
5. The stator has teeth that protrude radially inward, The outermost oil hole in the radial direction is formed radially outward from the teeth. The motor cooling device according to claim 1, wherein all oil holes except for the outermost radial oil hole are formed on the teeth.