Concentrated winding inner stator of direct oil cooling outer rotor hub motor

Abstract

The invention discloses a concentrated winding inner stator of a direct oil-cooled outer rotor hub motor, which comprises a structural electrical part and a U-shaped cooling loop sealing system, and is characterized in that the structural electrical part provides a support and electrical loop for the inner stator; the U-shaped cooling loop sealing system and the structural electrical part form a U-shaped cooling loop in which the bottoms in the grooves of the inner stator are connected in parallel and then connected in series, and an oil inlet and an oil outlet of the U-shaped cooling loop are adjacent. Cooling oil in the grooves makes direct large-area contact with the windings, the cooling effect is greatly improved compared with an existing permanent magnet outer rotor water-cooled hub motor, a cooling loop does not need to be slotted in the tooth parts and the yoke parts of the iron cores, local flux density of the tooth parts and the yoke parts is prevented from being increased, water channels do not need to be arranged in the stator support, an ultra-thin structure can be adopted, and cost is reduced. A larger space is provided for the brake, meanwhile, the coil of the inner stator can be kept at a low temperature all the time, and the stator resistance cannot be continuously increased due to the heat effect, so that loss is not increased.

Description

Technical Field

[0001] The present invention relates to an external rotor permanent magnet hub motor for vehicle drive used in pure electric or hybrid passenger cars and light commercial vehicles, belonging to the technical field of hub motors. Background Art

[0002] In the drive motors of new energy vehicles, the main type is the external stator and internal rotor motor. Among them, the oil cooling technology has developed rapidly, but basically it is in the mode of slotting for cooling on the outer circle of the iron core or spraying at the winding end. There are very few cases of slotting oil cooling at the contact parts between the teeth or yokes of the iron core and the winding. Both of the above two types of cooling have two defects. First, due to the need to slot on the iron core, the magnetic density of the stator yoke or teeth increases, so it is necessary to increase the thickness of the teeth or yokes, increasing the volume of the motor. Secondly, the heat generation of the motor winding in the slot is very large, and it is impossible to directly cool in the slot. Or even if slots are opened in the teeth, due to the very limited contact area between the cooling oil and the winding, the final heat dissipation effect is relatively limited.

[0003] In the application of external rotor hub motors in new energy vehicles, the external rotor permanent magnet motor is directly installed in the wheel, which brings a series of benefits to the whole vehicle. The motor directly drives the wheel, the transmission chain is greatly simplified compared with the central motor drive, the transmission efficiency is greatly improved, and the overall vehicle layout is very simple, providing a larger space inside the vehicle. While bringing these advantages, due to the limited space and harsh environment inside the wheel, the external rotor hub motor has very high cooling requirements for the motor.

[0004] Most of the external rotor hub motors are concentrated winding internal stators. Since the stator is inside and the rotor is outside, if an oil cooling scheme is implemented, the cooling oil will flow to the rotor housing. The rotor housing rotates at high speed, and the oil impact on the housing brings unacceptable stirring noise and stirring mechanical loss. The oil on the rotor housing also makes the dynamic balance worse, and at the same time, it is difficult to collect the cooling oil. Due to a series of problems, the concentrated winding internal stator of the current external rotor hub motor adopts the method of arranging water channels inside the bracket of the internal stator, and the coolant circulates in the water channels to cool the bracket, and then the bracket cools the iron core of the internal stator, and the iron core then cools the winding. The cooling effect is poor. And because there are water channels, the bracket of the internal stator becomes relatively thick in the radial direction, compressing the space for placing the brake inside, often resulting in insufficient mechanical braking ability of the hub motor. Summary of the Invention

[0005] The purpose of the present invention is to provide a concentrated winding internal stator of an external rotor hub motor with direct oil cooling for the deficiencies of the prior art, so as to solve the problems raised in the background art.

[0006] To achieve the above object, the present invention provides the following technical solution: A concentrated winding inner stator of a direct oil-cooled outer rotor hub motor, including a structural electrical part and a U-shaped cooling circuit sealing system. The structural electrical part includes a stator bracket, a stator core, stator outer teeth, slot insulation, concentrated winding coils, and three-phase cables, providing support and an electrical circuit for the inner stator.

[0007] The U-shaped cooling circuit sealing system is composed of a non-magnetic ultra-thin sheath, an outlet end plate, a non-outlet end plate, an epoxy sealing putty strip, a rubber sealing strip, an oil cooling pipe joint, a cable sealing joint, and an O-ring, and together with the structural electrical part, forms a U-shaped cooling circuit that is connected in parallel at the bottom of the slots in the inner stator and then in series.

[0008] As a preferred technical solution of the present invention, each coil of the concentrated winding inner stator is installed on each stator tooth. Whether it is a flat wire coil or a round wire coil, there needs to be a certain gap between the two coils in each slot to leave space for winding or coil assembly. The present invention utilizes the space between the two coils in the slot for large-area direct cooling.

[0009] As a preferred technical solution of the present invention, the stator core is thermally sleeved on the outside of the stator bracket. Cooling grooves are opened on the outer surface of the stator bracket facing each core slot, through which cooling oil can flow. Slot insulation is laid in the stator slots. After the concentrated winding coils are wound, they are installed into the tooth parts of the stator core, and then the connecting wires between the coils are welded at the outlet end. The three-phase cables are welded and insulated at the three-phase outlet parts. The stator outer teeth are separately punched. After the coils are installed, the stator outer teeth are installed on the stator core, thus forming a coil-core assembly.

[0010] As a preferred technical solution of the present invention, O-rings are installed in the slots at both ends of the stator bracket. A non-magnetic ultra-thin sheath is thermally sleeved on the outer circle of the coil-core assembly, and the non-magnetic ultra-thin sheath is made of non-magnetic stainless steel material with a thickness of 0.5 mm. The non-magnetic ultra-thin sheath isolates the cooling oil from the external space. Then, epoxy sealing putty is pressed into a formed shape at the set position at the coil end. After the epoxy sealing putty cures, a rubber sealing strip is installed on its outside. Each assembly of an epoxy sealing putty strip and a rubber sealing strip forms a flow channel separator. There are four flow channel separators at the non-outlet end and five flow channel separators at the outlet end.

[0011] As a preferred technical solution of the present invention, an O-ring is sleeved on the outer circle of the non-outlet end plate, and then the sealing strip clamping position of the end plate is aligned with the flow channel separator at the coil end one by one, and the non-outlet end plate is pressed into the coil-core assembly in place, and the connecting bolts are tightened.

[0012] As a preferred technical solution of the present invention, an O-ring seal is sleeved on the outer circle of the end plate at the outgoing line end. The sealant strip clamping positions of the end plate correspond one by one to the flow channel separation strips at the ends of the coils. The three cables of the three phases are led out through the holes on the end plate, and then the end plate at the outgoing line end is pressed into the coil iron core assembly in place, and the connecting bolts are tightened.

[0013] As a preferred technical solution of the present invention, three cable sealing joints are installed on the end plate at the outgoing line end and tightened to prevent leakage, and then two oil cooling pipe joints are installed.

[0014] As a preferred technical solution of the present invention, the direction of the cooling circuit is determined as follows: according to the gap between the coils in the slots and the dimensions of the cooling slots on the stator bracket, combined with the heat dissipation loss of the outer rotor hub motor, N slots are connected in parallel to form a group, and the total number of slots divided by N gives the total number of groups. The head and tail of each adjacent group are connected in series to form the total U-shaped cooling circuit, and the oil inlet and the oil outlet are adjacent.

[0015] Compared with the prior art, the present invention provides a concentrated winding inner stator of a direct oil-cooled outer rotor hub motor, having the following beneficial effects:

[0016] 1. There is originally a gap between the two coils in each slot of the concentrated winding inner stator. The present invention uses this gap for cooling, and the cooling oil in the slot is in direct large-area contact with the winding. The cooling effect is greatly improved compared with the existing outer rotor water-cooled hub motor, and is also significantly better than the existing oil-cooled motor with an outer stator and an inner rotor.

[0017] 2. The present invention uses a non-magnetic ultra-thin sheath to achieve external sealing of the stator, and the cooling oil only circulates inside the stator, solving the problems caused by the leakage of the cooling oil to the rotor housing. The U-shaped cooling circuit does not need to be grooved on the tooth part and the yoke part of the iron core, avoiding increasing the local magnetic density of the tooth part and the yoke part, and will not weaken the performance of the hub motor.

[0018] 3. The present invention adopts an oil circuit method of parallel connection of the stator slots and the cooling slots on the stator bracket, which can cool the winding and the iron core together. At the same time, the oil inlet and the oil outlet of the cooling circuit are adjacent, the temperature of the oil inlet is lower, and the temperature of the oil outlet is higher, and the two can conduct heat balance, further improving the cooling effect.

[0019] 4. The inner part of the stator bracket of the present invention does not require the liquid cooling circuit commonly used in the existing outer rotor hub motor, so the stator bracket can be designed with a thinner size in the radial direction. In this way, the inner cavity size of the stator bracket is larger, and a larger brake disc can be designed, thereby improving the mechanical braking ability of the hub motor and solving the problem of insufficient mechanical braking of the hub motor.

[0020] 5. The coils of the inner stator of the present invention can always maintain a relatively low temperature and are basically not affected by the ambient temperature. Therefore, the stator resistance will not continuously increase due to the thermal effect, the copper loss during operation is small, the motor has higher efficiency, and at the same time, the motor can also output a larger torque, further improving the torque density of the in-wheel motor. Description of the Drawings

[0021] Figure 1 It is a diagram of the U-shaped oil cooling circuit in parallel in the slot and at the bottom of the slot of the present invention;

[0022] Figure 2 It is a front view of the concentrated winding inner stator of a direct oil-cooled outer rotor in-wheel motor of the present invention;

[0023] Figure 3 It is a sectional view of the concentrated winding inner stator of a direct oil-cooled outer rotor in-wheel motor of the present invention;

[0024] Figure 4 It is a diagram of the stator bracket of the present invention;

[0025] Figure 5 It is a diagram of the stator core of the present invention;

[0026] Figure 6 It is a diagram of the outer teeth of the stator of the present invention;

[0027] Figure 7 It is a diagram of a single concentrated winding coil of the present invention;

[0028] Figure 8 It is a diagram of the coil core assembly of the present invention;

[0029] Figure 9 It is a schematic diagram of the formed epoxy sealant strip (lead end and non-lead end) of the present invention;

[0030] Figure 10 It is a schematic diagram of the rubber sealant strip (lead end and non-lead end) of the present invention;

[0031] Figure 11 It is a schematic diagram of the flow channel partition strip (combination of rubber sealant strip and epoxy sealant strip) of the present invention;

[0032] Figure 12 It is a diagram of the coil core assembly with a non-magnetic ultra-thin sheath and a flow channel partition strip of the present invention;

[0033] Figure 13 It is a schematic diagram of the distribution position of the flow channel partition strip at the lead end coil end of the present invention;

[0034] Figure 14 It is a schematic diagram of the distribution position of the flow channel partition strip at the non-lead end coil end of the present invention;

[0035] Figure 15 It is the end plate of the outgoing line of the present invention, as shown in Fig. 2-1;

[0036] Figure 16 It is the end plate of the outgoing line of the present invention, as shown in Fig. 2-2;

[0037] Figure 17 It is the end plate of the non-outgoing line of the present invention, as shown in Fig. 2-1;

[0038] Figure 18 It is the end plate of the non-outgoing line of the present invention, as shown in Fig. 2-2.

[0039] Reference numerals: 1. Oil cooling pipe joint; 2. First O-ring seal; 3. Rubber sealing strip at the outgoing line end; 4. Epoxy sealing putty strip at the outgoing line end; 5. Outer teeth of the stator; 6. Non-magnetic ultra-thin sheath; 7. Epoxy sealing putty strip at the non-outgoing line end; 8. Rubber sealing strip at the non-outgoing line end; 9. Second O-ring seal; 10. Concentrated winding coil; 11. End plate of the non-outgoing line; 12. Third O-ring seal; 13. Stator core; 14. Stator bracket; 15. End plate of the outgoing line; 16. Fourth O-ring seal; 17. Connecting bolt; 18. Three-phase cable; 19. Cable sealing joint; 20. Cooling groove of the stator bracket; 21. Flow path dividing strip; 22. Sealing strip clamping position. Detailed implementation manners

[0040] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0041] Please refer to Figures 1 - 18 , an embodiment provided by the present invention:

[0042] As Figure 2 , 3 shown, the concentrated winding inner stator of the direct oil-cooled outer rotor hub motor mainly includes a structural electrical part and a U-shaped cooling circuit sealing system.

[0043] The structural electrical part includes the stator support 14, the stator core 13, the stator outer teeth 5, slot insulation, concentrated winding coils 10, and three-phase cables 18, which provide support and electrical circuits for the entire inner stator. The U-shaped cooling circuit sealing system consists of a non-magnetic ultra-thin sheath 6, an outlet end plate 15, a non-outlet end plate 11, flow channel partition strips 21, oil-cooling pipe connectors 1, cable sealing connectors 19, a first O-ring 2, a second O-ring 9, a third O-ring 12, and a fourth O-ring 16. Together with the structural electrical part, they form a U-shaped cooling circuit that is connected in parallel at the bottom of the slots in the inner stator and then in series.

[0044] Each inner stator has 24 concentrated winding coils 10. The concentrated winding coils 10 are assembled on the teeth of the stator core 13, and there is a certain gap between two coils in each slot. The present invention utilizes the space between two coils in the slot for direct cooling of a large area of the winding.

[0045] As Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 8 shown, the stator core 13 is shrink-fitted on the outer circle of the stator support 14. The stator support 14 is provided with stator support cooling grooves 20 at the outer surface parts facing each iron core slot, through which cooling oil can flow. Slot insulation is laid in the slots of the stator core 13. After the 24 concentrated winding coils 10 are wound, they are installed on the teeth of the stator core 13. Then, the connecting wires between the coils are welded at the outlet end, and three three-phase cables 18 are welded and insulated at the three-phase outlet parts. The 24 stator outer teeth 5 are individually punched. After the coils are installed, the stator outer teeth 5 are installed on the teeth of the stator core 13, thus forming a coil core assembly.

[0046] The third O-ring 12 and the fourth O-ring 16 are installed in the slots at both ends of the stator support 14. The non-magnetic ultra-thin sheath 6 is shrink-fitted on the outer circle of the coil core assembly. The non-magnetic ultra-thin sheath 6 is made of non-magnetic stainless steel material with a thickness of 0.5 mm, which isolates the cooling oil from the external space.

[0047] As Figures 9 - 18 shown, epoxy sealing putty is pressed into a formed shape at the designated positions at both ends of the coil, and after curing, an outlet-end epoxy sealing putty strip 4 and a non-outlet-end epoxy sealing putty strip 7 are formed. An outlet-end rubber sealing strip 3 and a non-outlet-end rubber sealing strip 8 are respectively installed outside them. The assembly of each epoxy sealing putty strip and rubber sealing strip forms a flow channel partition strip 21. There are four flow channel partition strips 21 at the non-outlet end and five flow channel partition strips 21 at the outlet end.

[0048] Put the second O-ring seal 9 on the outer circle of the non-outlet end plate 11. Then, align the four seal strip slots 22 of the end plate with the flow channel partition strips 21 at the end of the coil respectively, press the non-outlet end plate 11 into the coil iron core assembly until it is in place, and tighten the connecting bolts 17.

[0049] Put the first O-ring seal 2 on the outer circle of the outlet end plate 15. Align the five seal strip slots 22 of the end plate with the flow channel partition strips 21 at the end of the coil respectively. The three-phase cables 18 are led out through the holes on the end plate. Then, press the outlet end plate 15 into the coil iron core assembly until it is in place, and tighten the connecting bolts 17.

[0050] Install three cable seal joints 19 on the outlet end plate 15 and tighten them to prevent leakage. Then, install two oil cooling pipe joints 1.

[0051] In this embodiment, the stator core 13 has a total of 24 slots. Every three slots form a group. The cooling between the three slots is in parallel. There are a total of eight groups. The cooling between the groups is in series, forming a U-shaped oil cooling circuit with parallel connection inside and at the bottom of the slots as shown in Figure 1 the figure.

[0052] There are five flow channel partition strips 21 at the outlet end. Their positions need to be arranged strictly according to Figure Ten three. There are four flow channel partition strips 21 at the non-outlet end. Their positions need to be arranged strictly according to Figure Ten four. There are five seal strip slots 22 on the outlet end plate 15, which are distributed according to Figure 15 the figure. There are four seal strip slots 22 on the non-outlet end plate 11, which are distributed according to Figure 17 the figure. The flow channel partition strips 21 and the seal strip slots 22 are the key to forming the U-shaped oil cooling circuit.

[0053] The group of slots 1, 2, and 3 is opposite to the oil inlet. The group of slots 22 - 24 is the oil outlet. Of course, due to complete symmetry, the oil inlet and the oil outlet can be swapped, and the cooling effect is the same.

[0054] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A concentrated winding inner stator of a direct oil-cooled outer rotor hub motor, comprising a structural electrical part and a U-shaped cooling circuit sealing system, characterized in that: The electrical part of the structure includes a stator support (14), a stator core (13), stator outer teeth (5), slot insulation, concentrated winding coils (10), and three-phase cables (18), which provide support and an electrical circuit for the inner stator. The U-shaped cooling circuit sealing system consists of a non-magnetic ultra-thin sheath (6), an outlet end plate (15), a non-outlet end plate (11), a flow channel separator (21), an oil cooling pipe joint (1), a cable sealing joint (19), and O-ring seals. Together with the electrical part of the structure, it forms a U-shaped cooling circuit that is parallel in the slot and at the bottom of the slot of the inner stator and then connected in series.

2. The concentrated winding inner stator of a direct oil-cooled outer rotor hub motor according to claim 1, characterized in that: Each coil of the concentrated winding inner stator is installed on each stator tooth. Whether it is a flat wire coil or a round wire coil, there needs to be a certain gap between the two coils in each slot to leave space for winding or coil assembly. This gap constitutes the in-slot cooling circuit of the present invention.

3. The concentrated winding inner stator of a direct oil-cooled outer rotor hub motor according to claim 1, characterized in that: The stator core (13) is thermally sleeved outside the stator support (14). The outer surface of the stator support (14) facing each core slot is provided with cooling grooves, which are connected in parallel with the in-slot cooling circuit to achieve a better cooling effect.

4. The concentrated winding inner stator of a direct oil-cooled outer rotor hub motor according to claim 1, wherein: A non-magnetic ultra-thin sheath (6) is thermally sleeved on the outer circumference of the coil core assembly. The sheath (6) is made of a non-magnetic material and has an ultra-thin thickness. The non-magnetic ultra-thin sheath (6) isolates the cooling oil from the external space.

5. The concentrated winding inner stator of a direct oil-cooled outer rotor hub motor according to claim 1, characterized in that: The flow channel separators (21) are distributed at both ends of the coil. They are formed by pressing epoxy sealant clay into a set shape at a set position. After the epoxy sealant clay cures, a rubber seal strip is installed outside it. The flow channel separators determine the direction of the U-shaped cooling circuit.

6. The concentrated winding inner stator of a direct oil-cooled outer rotor hub motor according to claim 1, characterized in that: The non-outlet end plate (11) has a seal strip slot (22), which is in one-to-one correspondence with the flow channel separator (21) at the end of the non-outlet end coil. The outlet end plate (15) has a seal strip slot (22), which is in one-to-one correspondence with the flow channel separator (21) at the end of the outlet end coil.

7. The concentrated winding inner stator of a direct oil-cooled outer rotor hub motor according to claim 1, characterized in that: The direction of the cooling circuit is determined as follows: According to the gap between the coils in the slot and the size of the cooling grooves on the stator support (14), combined with the heat loss of the outer rotor hub motor, N slots are connected in parallel to form a group. The total number of slots divided by N gives the total number of groups. The heads and tails of adjacent groups are connected in series to form the total U-shaped cooling circuit, and the oil inlet and outlet are adjacent.

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