Motor cooling structure and permanent magnet synchronous motor for electric vehicle

Abstract

The present invention discloses a motor cooling structure and a permanent magnet synchronous motor for electric vehicles, including a stator cooling oil circuit and a rotor cooling oil circuit; the rotor is formed by closely stacking three types of annular silicon steel sheets with consistent radial dimensions, wherein the first type of silicon steel sheets are axially arranged at both ends of the rotor for closing the oil circuit; the second type of silicon steel sheets are closely attached to the first type of silicon steel sheets and are axially stacked from both ends to the center; the third type of silicon steel sheets are closely attached to the second type of silicon steel sheets at both ends, and a rotor cooling oil circuit is formed on the periphery of the third type of silicon steel sheets, which is connected to the oil inlet and outlet of the cooling oil circuit of the rotating shaft. Compared with the existing cooling structure, the cooling efficiency of the stator is effectively improved; at the same time, a rotor cooling oil circuit is added to cool the magnetic steel on the rotor, ensuring the stable working performance of the magnetic steel; it can effectively improve the working efficiency and working life of the motor, reduce the size of the motor, and improve the power density of the motor.

Description

Technical Field

[0001] The invention relates to the field of cooling structures of permanent magnet synchronous motors for electric vehicles, and in particular to a permanent magnet synchronous motor for electric vehicles and a cooling structure thereof. Background Art

[0002] New energy vehicles are playing an increasingly important role in improving automobile fuel consumption and emissions. As an indispensable power source for new energy vehicles, motors can provide driving force for vehicles. Permanent magnet synchronous motors are currently the most commonly used motors in China because of their large starting torque and stable working conditions.

[0003] Permanent magnet synchronous motors will generate copper loss, iron loss, mechanical loss and other losses when working, and copper loss and iron loss account for a large proportion of these losses. Copper loss is mainly caused by the loss of wire resistance after the stator winding is energized, and iron loss is mainly caused by hysteresis loss and eddy current loss caused by magnetic flux in the iron core. These losses are basically manifested in the form of heat, which is also the fundamental reason why heat dissipation is required when the motor is working.

[0004] The prior art generally dissipates heat from the motor stator by setting a coolant flow channel on the motor housing. Patent CN109104032A discloses a motor and its cooling housing structure, which essentially divides the motor housing into an outer shell and an inner shell, and changes the form of processing the flow channel groove on the inner circumference of the original motor housing to processing the coolant flow channel groove on the inner shell, so as to achieve the purpose of liquid cooling and heat dissipation of the motor, reducing the machining difficulty and manufacturing cost; Patent CN108551235A discloses a motor and its cooling system, which essentially processes the coolant flow channel groove on the motor housing, stator core and inner bracket, so that the coolant can enter the inside of the stator core, directly contact the heating element and take away the heat, thereby improving the heat dissipation efficiency of the motor.

[0005] By comparing with the existing technology, it can be found that the existing motor cooling system mainly improves the heat dissipation efficiency of the motor stator by changing the design and processing form of the coolant flow channel, and there is no cooling system that can take into account the heat dissipation of the permanent magnet on the motor rotor. With the increasingly strong momentum of the development of new energy vehicles, major car companies are pursuing higher and higher vehicle power consumption and costs, and as a result, the performance requirements for motors are also getting higher and higher. At present, motors are developing in the direction of higher power density, more stable working performance, and longer working life. Therefore, motors are developing towards high speed and miniaturization. As the motor speed and power density increase, the heat generated on the motor rotor will also be not negligible, and the heat dissipation requirements of the motor will also have new standards. The original motor cooling system that only dissipates heat for the motor stator can no longer meet the new needs of the current motor development. However, due to the rotation characteristics of the rotor itself, its cooling system cannot be simply applied or referred to the stator cooling method. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a motor cooling structure and a permanent magnet synchronous motor for electric vehicles, which can dissipate heat from the stator and rotor of the motor at the same time, thereby achieving the purpose of improving the cooling efficiency and service life of the motor.

[0007] In order to solve the above problems, the present invention provides the following technical solutions:

[0008] A motor cooling structure includes a stator, a rotor and a rotating shaft disposed by an outer casing, and an oil pump; the structure is characterized in that it includes a stator cooling oil circuit and a rotor cooling oil circuit;

[0009] The stator cooling oil circuit is connected to the oil pump through the first oil pipe, and is arranged to enter and exit from the two end surfaces of the stator plastic-sealed shell, forming a first cooling oil channel that runs axially through the outer cylinder of the stator core and the inner cylinder of the stator plastic-sealed shell, and a second cooling oil channel that runs through the stator core is arranged axially; a gap is arranged along the axis between the inner wall of the stator plastic-sealed shell and the outer wall of the built-in stator core as a third cooling oil channel; the first cooling oil channel, both ends of the second cooling oil channel, and the third cooling oil channel are respectively connected to the oil inlet and oil outlet of the stator cooling oil circuit;

[0010] The rotor cooling oil circuit is connected to the oil pump through a second oil pipe; the rotating shaft is a non-through shaft with hollow ends and a solid middle, one end of which is connected to the oil pump as the cooling oil circuit oil inlet, and the other end is the cooling oil circuit oil outlet; radial oil inlet grooves and radial oil outlet grooves are arranged along the circumference of the rotating shaft, the radial oil inlet grooves are radially connected to the cooling oil circuit oil inlet, and the radial oil outlet grooves are radially connected to the cooling oil circuit oil outlet; a plurality of rotor cooling oil circuits arranged axially are arranged at intervals on the rotor arranged outside the rotating shaft; each rotor cooling oil circuit extends radially toward the center of the rotating shaft and is respectively connected to a corresponding set of radial oil inlet grooves and radial oil outlet grooves, forming a passage from the cooling oil circuit oil inlet through the rotating shaft and the inside of the rotor to the cooling oil circuit oil outlet;

[0011] The rotor is composed of three types of closely stacked annular silicon steel sheets with consistent radial dimensions, wherein the first type of silicon steel sheets are axially arranged at both ends of the rotor for closing the oil circuit; the second type of silicon steel sheets are closely attached to the first type of silicon steel sheets and are axially stacked from both ends to the center; the third type of silicon steel sheets are closely attached between the second type of silicon steel sheets at both ends, and a rotor cooling oil circuit is formed on the periphery of the third type of silicon steel sheets, which are respectively connected to the oil inlet and outlet of the cooling oil circuit of the shaft.

[0012] Furthermore, the centers of the oil groove through holes on various silicon steel sheets on the third type silicon steel sheet layer are sequentially connected axially into straight lines or spiral lines, so that the axial section of the rotor cooling oil circuit is an axial cooling pipe or a spiral cooling pipe.

[0013] Furthermore, the axial section of the rotor cooling oil circuit on the third type of silicon steel sheet layer is arranged as a rotor forward cooling oil channel and a rotor reverse cooling oil channel, and a forward one-way circulation valve and a reverse one-way circulation valve are respectively provided at the inlet of the shaft cooling oil circuit. When the motor rotates forward, the forward one-way circulation valve opens and the reverse one-way circulation valve is closed; when the motor rotates forward, the forward one-way circulation valve opens and the reverse one-way circulation valve is closed.

[0014] Furthermore, the first type of silicon steel sheet layer is provided with permanent magnets and positioning grooves for arranging the permanent magnets; the second type of silicon steel sheet layer is provided with positioning grooves for arranging the permanent magnets corresponding to the first type of silicon steel sheet layer, and a number of axial sections of the rotor cooling oil path connected to the radial oil inlet groove and the radial oil outlet groove are arranged between the positioning grooves along the circumferential direction; the number of each radial section is consistent with the number of pole pairs of the permanent magnet, and its shape can be designed into different shapes according to design requirements; the second type of silicon steel sheet layer is provided with positioning grooves for arranging the permanent magnets corresponding to the second type of silicon steel sheet layer, and a number of axial sections of the rotor cooling oil path are arranged between the positioning grooves along the circumferential direction.

[0015] Furthermore, the stator plastic-sealed shell has a detachable end cover, and a cooling oil inlet is provided on one end surface of the end cover close to the oil pump, and a cooling oil outlet is provided on the other end surface. The oil outlet of the first oil inlet pipe is connected to the oil inlet on the end cover of the stator plastic-sealed shell. The cooling oil enters the stator plastic-sealed shell and directly contacts the heat-generating components such as the stator and windings to take away the heat, and then flows out from the oil outlet at the other end of the stator plastic-sealed shell to form a stator cooling oil circuit.

[0016] Furthermore, the rotor cooling oil circuits are evenly distributed along the circumference of the rotor, and their positions should correspond to the arrangement positions of the permanent magnets on the rotor, and their number should correspond to the number of pole pairs of the permanent magnets arranged on the rotor.

[0017] Furthermore, the inner wall surface of the inner layer wall of the stator plastic shell is provided with positioning teeth, and the inner ring cylinder wall surface of the stator core is provided with grooves that cooperate with the positioning teeth to fix the stator circumferentially, and the axial gap formed between the grooves and the positioning teeth also serves as the third cooling oil channel of the stator.

[0018] Furthermore, the oil pump is coaxial with the shaft. When the motor starts working, the oil pump starts working along with the rotation of the shaft. The faster the shaft rotates, the more oil the oil pump will pump. The slower the shaft rotates, the less oil the oil pump will pump.

[0019] Furthermore, one-way valves should be provided at the oil inlets of the first oil pipe and the second oil pipe.

[0020] A permanent magnet synchronous motor for electric vehicles is characterized by adopting the above motor cooling structure.

[0021] Therefore, the present invention discloses a permanent magnet synchronous motor for electric vehicles and its cooling structure, which belongs to the technical field of electromechanical equipment. The cooling structure includes a motor stator plastic-sealed shell, a stator, a rotor, a rotating shaft, an oil pump, a first oil pipe and a second oil pipe; wherein, an oil inlet and an oil outlet are arranged on the stator plastic-sealed shell, an internal cooling oil circuit is arranged on the rotor, and the rotating shaft is a non-through shaft with hollow ends and a solid middle, one end is used as the cooling oil circuit oil inlet, and the other end is used as the cooling oil circuit oil outlet, and an oil inlet groove and an oil outlet groove corresponding to the rotor cooling oil circuit are arranged along the circumference; the oil pump, the first oil pipe and the stator plastic-sealed shell constitute the stator cooling oil circuit, realizing direct contact and cooling of the coolant with the stator core and winding; the oil pump, the second oil pipe, the rotating shaft and the rotor internal cooling oil circuit constitute the rotor cooling oil circuit, realizing cooling of the magnetic steel on the rotor. The cooling oil enters the shaft along the cooling oil circuit inlet on the shaft, then flows into the rotor cooling oil circuit inside the rotor from the oil inlet groove on the shaft to cool the magnetic steel on the rotor, and then enters the cooling oil circuit outlet on the shaft from the oil outlet groove.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: the stator cooling oil circuit of the present invention is concentrated in the stator plastic-sealed shell. After the cooling oil enters the plastic-sealed shell from the first pipeline, it will fill the entire stator plastic-sealed shell, directly contact with heating elements such as the stator core and the winding, and then pass through the entire stator along the gap between the stator core and the outer end surface of the plastic-sealed shell, the cooling oil groove on the stator core and the gap between the stator core and the inner end surface of the plastic-sealed shell, and flow out from the oil outlet, taking away the heat of the stator, thereby greatly improving the cooling efficiency of the stator. In addition, due to the existence of the plastic-sealed shell, the cooling oil will not flow into the air gap between the stator and the rotor, thus avoiding the loss of oil stirring. The setting of the rotor cooling oil circuit will enable the motor rotor to dissipate heat better at medium and high speeds, ensuring that the performance of the permanent magnets and silicon steel sheets on the motor rotor will not decrease due to the increase in temperature, so that the working performance of the permanent magnets and silicon steel sheets remains stable, the working life is greatly increased, and the overall working efficiency of the motor will also be increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 A schematic diagram of an embodiment of a permanent magnet synchronous motor for an electric vehicle and a cooling structure thereof according to the present invention;

[0025] Figure 2 A schematic diagram of an embodiment of a cooling structure of a stator of the present invention (a left side view after the end cover of the stator plastic housing is removed);

[0026] Figure 3 It is a schematic diagram of the assembly of the rotor and the rotating shaft embodiment;

[0027] Figure 4 is a schematic diagram of an embodiment of a cooling structure of a rotor;

[0028] Figure 5 is a schematic diagram of an embodiment of a first type of silicon steel sheet;

[0029] Figure 6 is a schematic diagram of an embodiment of a second type of silicon steel sheet;

[0030] Figure 7 is a schematic diagram of an embodiment of a third type of silicon steel sheet;

[0031] Figure 8 is a perspective schematic diagram of an embodiment of a rotating shaft;

[0032] Fig. 9 It is a cross-sectional schematic diagram of an embodiment of a rotating shaft. DETAILED DESCRIPTION

[0033] The following will be combined with the attached embodiment of the present invention Figure 1-9 , the technical solutions in the embodiments of the present invention are described completely and clearly. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field under the premise of creative work are within the scope of protection of the present invention.

[0034] like Figure 1-Figure 9 The cooling structure of the permanent magnet synchronous motor for electric vehicles provided by the embodiment of the present invention includes: a stator plastic package shell 1, a stator 2, a rotor 3, a rotating shaft 4, an oil pump 5, a first oil pipe 6 and a second oil pipe 7; wherein the oil pump 5, the first oil pipe 6, the stator plastic package shell 1, and the internal cooling oil circuit on the stator 2 together constitute the stator cooling oil circuit; the oil pump 5, the second oil pipe 7, the rotating shaft 4 and the internal cooling oil circuit of the rotor together constitute the rotor cooling oil circuit.

[0035] The above-mentioned stator plastic-sealed shell 1 is a double-layer hollow cylinder, the cylinder has an inner wall and an outer wall coaxially spaced and sleeved, the right end surface connects the inner wall and the outer wall to form a ring, the left end surface of the cylinder is a detachable end cover 8, the end cover 8 is provided with a cooling oil inlet 9, the right end surface of the cylindrical ring is provided with a through-hole cooling oil outlet 10, and the inner wall surface of the inner wall is convexly provided with positioning teeth 11 for stator assembly. Preferably, the positioning teeth 11 are arranged parallel to the inner wall surface of the inner wall at intervals along the axial direction.

[0036] like Figure 1 and Figure 2The stator 2 is composed of a stator core 12 and a winding 13. The stator core 12 is a hollow annular cylinder, and a stator first cooling oil channel 14 is axially arranged on the outer surface of the annular cylinder; a through-hole stator second cooling oil channel 15 parallel to the stator first cooling oil channel 14 is arranged on the stator core 12 at a position close to the stator first cooling oil channel 14, which is used for cooling oil to pass through the stator core 12. The number, shape and size of the cooling oil channels (the stator first cooling oil channel 14 and the stator second cooling oil channel 15) are not limited and can be designed according to actual needs. The two cooling oil channels do not interfere with each other on the stator core 12, and are arranged in groups and at intervals, such as Figure 2 As shown in the end view; the groove 16 on the inner surface of the inner cylinder wall of the inner annular cylinder of the stator core 12 is used to cooperate with the positioning teeth 11 on the inner wall surface of the inner layer wall of the stator plastic shell 1 to fix the stator 2 circumferentially. At the same time, the axial gap formed between the groove 16 and the positioning teeth 11 also serves as the third stator cooling oil channel; the first stator cooling oil channel 14, the first stator cooling oil channel 15, and the third stator cooling oil channel are all flow channels that penetrate the stator core 12 along the axial direction, and together constitute the stator cooling oil circuit.

[0037] The working principle of the above-mentioned stator cooling oil circuit is that when the oil pump 5 is working, the cooling oil is pumped from the oil pump outlet 17 into the oil inlet of the first oil pipe 6, and the cooling oil flows along the first oil pipe 6 into the oil inlet 9 of the stator plastic-sealed shell 1, and enters the stator plastic-sealed shell 1, so that the inner cavity 32 in the entire stator plastic-sealed shell 1 is filled with cooling oil, which directly contacts with the heating elements such as the stator core 12 and the winding 13, and then axially from the stator first cooling oil channel 14 on the outer surface of the stator core 12, the stator second cooling oil channel 15 on the stator core, and the slot 16 on the inner surface of the stator core 12 and the positioning tooth 11 The oil flows through the third cooling channel of the stator and finally flows out from the oil outlet 10 on the right end face of the stator plastic-sealed shell 1, fully dissipating the heat of the outer surface, core, inner surface and winding 13 of the stator core 12, thereby improving the cooling efficiency of the stator 2; after the end cover 8 on the left end face of the entire stator plastic-sealed shell 1 is connected with the shell of the stator plastic-sealed shell 1, the first oil pipe 6 and the oil inlet 9 on the end cover 8 and the oil outlet 10 on the right end face and the oil outlet pipe 33 leading to the oil pump (preferably for recycling, the loop is not shown), it should be sealed to prevent the cooling oil from flowing into the stator and rotor and causing oil churning loss.

[0038] The internal cooling oil circuits of the rotor are sequentially distributed along the circumference of the rotor 3 , and their positions should correspond to the arrangement positions of the permanent magnets on the rotor 3 , and their number should correspond to the number of pole pairs of the permanent magnets on the rotor 3 .

[0039] like Figure 1-4The internal cooling oil circuit of the rotor is realized by designing and arranging three types of silicon steel sheets. The arrangement order of the three types of silicon steel sheets from left to right along the axial direction is first type silicon steel sheet 18, second type silicon steel sheet 21, third type silicon steel sheet 22, second type silicon steel sheet 21 and first type silicon steel sheet 18. Figure 4 , wherein the first type silicon steel sheets 18 are arranged at both axial ends of the rotor 3 and serve as the outer closed surfaces of the oil inlet pipe 19 and the oil outlet pipe 20 of the internal cooling oil circuit; the second type silicon steel sheets 21 are arranged close to the outer closed surfaces of the first type silicon steel sheets 18 formed by the innermost layer of the first type silicon steel sheets 18 toward the center layer of the rotor; the center layer of the rotor is entirely composed of the third type silicon steel sheets 22, which constitute the cooling pipes 23 of the internal cooling oil circuit of the rotor (such as Figure 3 and 4 As shown), it also serves as the inner closed surface of the oil inlet and oil outlet pipelines of the internal cooling oil circuit of the rotor; the first type silicon steel sheet 18, the second type silicon steel sheet 21 and the third type silicon steel sheet 22 together constitute the oil inlet and oil outlet pipelines of the internal cooling oil circuit of the rotor.

[0040] like Figure 5 The first type of silicon steel sheet 18 is only provided with a positioning groove 24 for arranging a permanent magnet; Figure 6 In addition to the positioning grooves 24 for arranging the permanent magnets, the second type of silicon steel sheet 21 also needs to be processed with oil grooves 30 for the oil inlet and outlet pipes. The number of oil grooves 30 in the oil outlet pipe is consistent with the number of pole pairs of the permanent magnets, and the shape can be designed into different shapes according to design requirements; Figure 7 In addition to the positioning grooves 24 for arranging the permanent magnets, the third type of silicon steel sheet 22 also needs to be processed with oil groove through holes 31 for the cooling pipe. The number of oil groove through holes 31 for the cooling pipe is consistent with the number of pole pairs of the permanent magnets. The shape of the oil groove through holes 31 can be designed into different shapes according to design requirements, but its shape must correspond to the shape of the end of the oil groove 30 of the oil outlet pipe close to the permanent magnet positioning groove.

[0041] like Figure 1 , Figure 3 , Figure 4 , Figure 8 and Fig. 9The rotating shaft 4 is a non-through shaft with hollow ends and a solid middle. One end is used as the cooling oil inlet 25, and the other end is used as the cooling oil outlet 26. The solid middle part is used to separate the cooling oil inlet from the oil outlet. The rotating shaft 4 is provided with oil inlet grooves 27 and oil outlet grooves 28 corresponding to the rotor oil inlet pipeline 19 and the oil outlet pipeline 20 respectively along the circumferential direction. The number of the oil inlet grooves 27 and the oil outlet grooves 28 is consistent with the number of the rotor oil inlet pipelines 19 and the oil outlet pipelines 20 on the rotating shaft 4. The shapes of the oil inlet grooves 27 and the oil outlet grooves 28 are consistent with the rotor oil inlet pipelines 19 and the oil outlet pipelines 20. The shapes are consistent; the number of oil inlet grooves 27 and oil outlet grooves 28 is consistent with the number of oil grooves 30 on the second type silicon steel sheet 21; the number of rotor oil inlet pipes 19 and oil outlet pipes 20 on the shaft 4 is consistent with the number of oil grooves 31 on the third type silicon steel sheet 22; the shaft 4 and the rotor 3 must be accurately positioned during installation to ensure the isocenter of the oil inlet groove 27 (oil outlet groove 28) and the oil inlet pipe 19 (oil outlet pipe 20) on the rotor; the oil inlet groove 27 (oil outlet groove 28) and the oil inlet pipe 19 (oil outlet pipe 20) on the rotor must be of the same size during processing.

[0042] like Figure 1 and Figure 3 The working principle of the above rotor cooling oil circuit is that when the oil pump 5 is working, the cooling oil is pumped from the oil pump outlet 17 into the oil inlet of the second oil pipe 7, the cooling oil flows along the second oil pipe 7 into the oil inlet 25 of the cooling oil circuit of the shaft 4, along the oil inlet groove 27 on the shaft 4 into the oil inlet pipe 19 of the internal cooling oil circuit on the rotor, flows through the cooling pipe 23 of the internal cooling oil circuit on the rotor, approaches the permanent magnet and takes away the heat, and then flows from the cooling pipe into the oil outlet pipe 20 of the internal cooling oil circuit of the rotor, and then flows out through the oil outlet groove 28 on the rotor 3 and the oil outlet 26 on the shaft 4; in this way, the cooling oil can take away the heat emitted from the rotor silicon steel sheet, the permanent magnet and the shaft, and dissipate the heat, further improving the overall heat dissipation efficiency of the motor, and ensuring that the performance of the permanent magnet and the silicon steel sheet will not decrease due to the increase in temperature, and at the same time can also extend the working life of the permanent magnet and the silicon steel sheet.

[0043] Optionally, the oil pump 5 is coaxial with the rotating shaft 4. When the motor starts working, the oil pump 5 starts working along with the rotation of the rotating shaft 4. The faster the rotating speed of the rotating shaft 4, the greater the oil pumping amount of the oil pump 5 will be. The slower the rotating speed of the rotating shaft 4, the less oil pumping amount of the oil pump 5 will be.

[0044] Optionally, a one-way valve 29 is provided at the oil inlet of the first oil pipe 6 and the second oil pipe 7 to control the cooling oil to only enter the first oil pipe 6 or the second oil pipe 7 from the oil outlet of the oil pump and not to flow in the reverse direction.

[0045] A plurality of third type silicon steel sheets 22 are stacked in sequence, so that the oil groove through holes 31 are connected in sequence to form a straight line or a spiral line, so that the axial section of the rotor cooling oil circuit is an axial cooling pipe or a spiral cooling pipe.

[0046] This embodiment of Figure 1-4 Only an example of a straight line segment is given. In another embodiment, the cooling oil channel in the cooling oil circuit inside the rotor 3 can be formed into a non-axial straight spiral channel by designing and arranging the third type silicon steel sheet 22 .

[0047] When designing the third type of silicon steel sheets 22, the center position of the oil groove through hole 31 should be radially from low to high and then to low along the stacking direction of the silicon steel sheets; when arranging, it should be ensured that the centers of different silicon steel sheets should be on the same straight line, thereby forming a spiral cooling oil channel. When the rotor 3 rotates, the cooling oil will be subjected to centrifugal force, and the spiral cooling oil channel can ensure that the cooling oil flows through the cooling oil channel more easily as the rotor rotates.

[0048] In another embodiment, the cooling oil channels in the above-mentioned rotor internal cooling oil circuit can be arranged as rotor forward cooling oil channels and rotor reverse cooling oil channels according to needs, and a forward one-way circulation valve and a reverse one-way circulation valve are respectively provided at the inlet of the cooling oil channel (the oil inlet 25 of the cooling oil circuit of the rotating shaft 4). When the motor rotates forward, the forward one-way circulation valve opens and the reverse one-way circulation valve closes; when the motor rotates forward, the forward one-way circulation valve opens and the reverse one-way circulation valve closes.

[0049] Compared with the existing cooling structure, this invention effectively improves the cooling efficiency of the stator; at the same time, a rotor cooling oil circuit is added to cool the magnetic steel on the rotor, ensuring the stable working performance of the magnetic steel; it can effectively improve the working efficiency and service life of the motor, reduce the size of the motor, and increase the power density of the motor.

[0050] Obviously, the above embodiments are only examples for clearly illustrating the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A motor cooling structure, comprising a stator, a rotor and a rotating shaft disposed by an outer casing, and an oil pump; characterized in that: It includes a stator cooling oil circuit and a rotor cooling oil circuit; The stator cooling oil circuit is connected with the oil pump through the first oil pipe, and is arranged to enter and exit from the two end surfaces of the stator plastic-sealed shell, forming a first cooling oil channel that runs axially through the outer cylinder of the stator core and the inner cylinder of the stator plastic-sealed shell, and at the same time, a second cooling oil channel that runs through the stator core is arranged axially; a gap is arranged along the axis between the inner wall of the stator plastic-sealed shell and the inner wall of the built-in stator core as a third cooling oil channel; the first cooling oil channel, both ends of the second cooling oil channel, and the third cooling oil channel are respectively connected with the oil inlet and oil outlet of the stator cooling oil circuit; the stator plastic-sealed shell has a detachable end cover, and a cooling oil inlet is arranged on one end surface of the end cover close to the oil pump, and a cooling oil outlet is arranged on the other end surface, the oil outlet of the first oil pipe is connected to the oil inlet on the end cover of the stator plastic-sealed shell, the cooling oil enters the stator plastic-sealed shell, directly contacts with the stator and the heating elements such as the winding and takes away the heat, and then flows out from the oil outlet at the other end of the stator plastic-sealed shell, forming a stator cooling oil circuit; A plurality of rotor cooling oil circuits arranged axially are arranged at intervals on the rotor arranged outside the rotating shaft; each rotor cooling oil circuit extends radially toward the center of the rotating shaft and is respectively connected to a corresponding set of radial oil inlet grooves and radial oil outlet grooves, forming a passage from the cooling oil circuit inlet through the rotating shaft and the inside of the rotor to the cooling oil circuit outlet; the rotor cooling oil circuit is connected to the oil pump through a second oil pipe; the rotating shaft is a non-through shaft with hollow ends and a solid middle, one end of which is connected to the oil pump as the cooling oil circuit inlet, and the other end is used as the cooling oil circuit outlet; radial oil inlet grooves and radial oil outlet grooves are arranged along the circumference of the rotating shaft, the radial oil inlet grooves are radially connected to the cooling oil circuit inlet, and the radial oil outlet grooves are radially connected to the cooling oil circuit outlet; The rotor is formed by three types of closely stacked annular silicon steel sheets with consistent radial dimensions, wherein the first type of silicon steel sheets are axially arranged at both ends of the rotor for closing the oil circuit; the second type of silicon steel sheets are closely attached to the first type of silicon steel sheets and are axially stacked from both ends to the center; the third type of silicon steel sheets are closely attached to the second type of silicon steel sheets at both ends, and a rotor cooling oil circuit is formed on the periphery of the third type of silicon steel sheets, which is respectively connected to the oil inlet and outlet of the cooling oil circuit of the rotating shaft; the centers of the oil groove through holes on the various types of silicon steel sheets on the third type of silicon steel sheet layer are sequentially connected along the axial direction to form a straight line or a spiral line, so that the axial section of the rotor cooling oil circuit is an axial cooling pipe or a spiral cooling pipe.

2. The motor cooling structure according to claim 1, characterized in that: The axial section of the rotor cooling oil circuit on the third type silicon steel sheet layer is arranged as a rotor forward cooling oil channel and a rotor reverse cooling oil channel. A forward one-way circulation valve and a reverse one-way circulation valve are respectively provided at the oil inlet of the shaft cooling oil circuit. When the motor rotates forward, the forward one-way circulation valve opens and the reverse one-way circulation valve is closed; when the motor rotates forward, the forward one-way circulation valve opens and the reverse one-way circulation valve is closed.

3. The motor cooling structure according to any one of claims 1 to 2, characterized in that: The first type of silicon steel sheet layer is provided with permanent magnets and positioning grooves for arranging permanent magnets; the second type of silicon steel sheet layer is provided with positioning grooves for arranging permanent magnets corresponding to the first type of silicon steel sheet layer, and a number of axial sections of the rotor cooling oil path connected to the radial oil inlet groove and the radial oil outlet groove are arranged between the positioning grooves along the circumferential direction; the number of each radial section is consistent with the number of pole pairs of the permanent magnet, and its shape can be designed into different shapes according to design requirements; the second type of silicon steel sheet layer is provided with positioning grooves for arranging permanent magnets corresponding to the second type of silicon steel sheet layer, and a number of axial sections of the rotor cooling oil path are arranged between the positioning grooves along the circumferential direction.

4. The motor cooling structure according to any one of claims 1 to 2, characterized in that: The rotor cooling oil passages are evenly distributed along the circumference of the rotor, and their positions should correspond to the arrangement positions of the permanent magnets on the rotor, and their number should correspond to the number of pole pairs of the permanent magnets arranged on the rotor.

5. The motor cooling structure according to any one of claims 1 to 2, characterized in that: The inner wall of the inner layer of the stator plastic shell is provided with positioning teeth, and the inner ring cylinder wall of the stator core is provided with grooves that cooperate with the positioning teeth to fix the stator circumferentially. The axial gap formed between the groove and the positioning teeth also serves as the third cooling oil channel of the stator.

6. The motor cooling structure according to any one of claims 1-2, characterized in that: The oil pump is coaxial with the rotating shaft. When the motor starts working, the oil pump starts working along with the rotation of the rotating shaft. The faster the rotating shaft rotates, the more oil the oil pump will pump, and the slower the rotating shaft rotates, the less oil the oil pump will pump.

7. The motor cooling structure according to any one of claims 1-2, characterized in that: One-way valves should be provided at the oil inlets of the first oil pipe and the second oil pipe.

8. A permanent magnet synchronous motor for electric vehicles, characterized in that The motor cooling structure according to any one of claims 1 to 7 is adopted.

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