Motor capable of removing dust and cooling and design method thereof

Abstract

The invention provides a motor capable of removing dust and cooling and a design method thereof, the motor comprises a motor shaft, a rotor structure, a stator structure and a motor shell, and the rotor structure is provided with an axially through heat exchange channel; and the dust removal flow guide structure is arranged to rotate based on the motor shaft, so that one part of airflow flowing into the motor rotationally flows out of the motor in the circumferential direction, and the rest part of the airflow flows out of the motor from the end, close to the dust removal flow guide structure, of the heat exchange channel through the end, away from the dust removal flow guide structure, of the heat exchange channel. According to the motor capable of removing dust and cooling provided by the invention, the influence of impurities in airflow on the internal structure and operation of the motor can be effectively avoided while efficient heat dissipation and cooling of the motor are ensured.

Description

Technical Field

[0001] This invention relates to the field of motor technology, specifically to a dust-removing and cooling motor and its design method. Background Technology

[0002] An electric motor is a device that converts electrical energy into mechanical energy by rotating a rotor relative to a stator. During its rotation, heat is inevitably generated. Due to differences in motor structure, performance, and operating environment, this heat will have different effects on the motor's operating status and service life. For motors with high power, high load, high power density, high speed, or high integration, good heat dissipation is an important guarantee for stable and continuous operation.

[0003] Current known methods for cooling motors include installing axially connected airflow paths (or heat exchange channels) on the motor rotor, and using axial flow fans or similar devices to drive external airflow through the motor's interior to remove the heat generated by rotation. However, while these methods establish heat exchange channels between the inside and outside of the motor to improve heat dissipation, they may also allow external dust to enter the motor. Summary of the Invention

[0004] To address the problems existing in the prior art, the present invention provides, through embodiments, a motor with a reasonable structure that can effectively remove dust and dissipate heat, and its design method.

[0005] A first aspect of the present invention provides a dust-removing and cooling motor, the motor comprising a motor shaft, a rotor structure, a stator structure, and a motor housing, wherein the rotor structure is provided with an axially penetrating heat exchange channel; the motor further comprises a dust removal and flow guiding structure configured such that, based on the rotation of the motor shaft, a portion of the airflow flowing into the motor rotates circumferentially and flows out of the motor, and the remaining portion flows out of the motor from one end of the heat exchange channel near the dust removal and flow guiding structure and through the other end away from the dust removal and flow guiding structure.

[0006] The dust-removing and cooling motor provided by this invention, by setting a dust-removing flow guiding structure, can guide a portion of the airflow flowing into the motor to flow out of the motor in a circumferential rotation, and guide the remaining airflow through a heat exchange channel. This effectively removes impurities from the airflow flowing into the motor, and also ensures that the remaining airflow exchanges the heat generated inside the motor to the outside of the motor. While ensuring efficient heat dissipation and cooling of the motor, it avoids the impact of impurities in the airflow on the internal structure and operation of the motor.

[0007] A second aspect of the present invention provides a design method for designing the aforementioned dust-removing and cooling motor, the design method comprising the following steps:

[0008] The first step is to analyze the composition of gaseous impurities in the environment in which the motor is used;

[0009] The second step is to design the dust removal and flow guiding structure of the motor based on the analysis results of gas impurity composition and the rated speed of the motor. Attached Figure Description

[0010] Figure 1 A schematic diagram of a dust-removing and cooling motor provided according to some embodiments of the present invention;

[0011] Figure 2 A top view of a dust-removing and cooling motor provided according to an embodiment of the present invention;

[0012] Figure 3A An exploded view of a dust-removing and cooling motor provided according to an embodiment of the present invention;

[0013] Figure 3B A front view of a dust-removing and cooling motor provided according to an embodiment of the present invention;

[0014] Figure 4A A half-sectional view of a dust-removing and cooling motor provided according to an embodiment of the present invention;

[0015] Figure 4B A cross-sectional view of a dust-removing and cooling motor provided according to an embodiment of the present invention;

[0016] Figure 5A This is a schematic diagram of the structure of a centrifugal impeller according to an embodiment of the present invention;

[0017] Figure 5B A top view of a centrifugal impeller provided according to an embodiment of the present invention;

[0018] Figure 5C A cross-sectional view of a centrifugal impeller provided according to an embodiment of the present invention;

[0019] Figure 5D A cross-sectional view of a centrifugal impeller provided according to an embodiment of the present invention;

[0020] Figure 5E This is a schematic diagram of the airflow of a dust-removing and cooling motor provided according to an embodiment of the present invention.

[0021] Figure 5F A schematic diagram of the airflow velocity distribution of a dust-removing and cooling motor provided according to an embodiment of the present invention;

[0022] Figure 5G This is a schematic diagram of the structure of a centrifugal impeller according to an embodiment of the present invention;

[0023] Figure 5H A top view of a centrifugal impeller provided according to an embodiment of the present invention;

[0024] Figure 6A This is a partially enlarged schematic diagram of the airflow of a dust-removing and cooling motor provided according to an embodiment of the present invention, and at the second airflow outlet.

[0025] Figure 6B This is a schematic diagram of the structure of the second airflow outlet provided according to an embodiment of the present invention;

[0026] Figure 6C This is a partially enlarged schematic diagram of the airflow at the second airflow outlet of a dust-removing and cooling motor provided according to an embodiment of the present invention.

[0027] Figure 6D This is a partially enlarged schematic diagram of the airflow at the second airflow outlet of a dust-removing and cooling motor provided according to an embodiment of the present invention.

[0028] Figure 7 An exploded view of a dust-removing and cooling motor provided according to an embodiment of the present invention;

[0029] Figure 8A This is a schematic diagram of the structure of the axial flow guide provided according to an embodiment of the present invention;

[0030] Figure 8B A half-sectional view of a dust-removing and cooling motor provided according to an embodiment of the present invention;

[0031] Figure 8C This is a schematic diagram of airflow near the axial guide section according to an embodiment of the present invention;

[0032] Figure 9A A schematic diagram of the airflow velocity distribution of a dust-removing and cooling motor provided according to an embodiment of the present invention;

[0033] Figure 9B A schematic diagram of the airflow velocity distribution of a dust-removing and cooling motor provided according to an embodiment of the present invention;

[0034] Figure 10A This is a schematic diagram of a rotor structure provided according to an embodiment of the present invention;

[0035] Figure 10B A side view of a rotor structure provided according to an embodiment of the present invention;

[0036] Figure 10C A cross-sectional view of a rotor structure provided according to an embodiment of the present invention;

[0037] Figure 11 A flowchart illustrating the design method of a dust-removing and cooling motor according to an embodiment of the present invention.

[0038] Numbers in the diagram

[0039] Motor housing 1, upper cover 11, motor housing 12, lower cover 13, upper bearing cover 14, lower bearing cover 15, airflow inlet 16, first airflow outlet 171, second airflow outlet 172, frustum 18, circumferential rotating channel 19, stator core 21, stator winding 22, rotor structure 3, heat exchange channel 31, guide ring 32, motor shaft 4, key 41, motor hole 42, upper bearing 51, lower bearing 52, centrifugal impeller 6, front disc 61, first annular region 611, first guide structure 612, second annular region 621, connecting part 622, second guide structure 623, blade 63, axial guide part 7, guide ring 71, support part 72, axial guide tooth 73, external airflow 81, circumferential rotating airflow 82, ejected airflow 83, heat exchange airflow 84, impurities 9. Detailed Implementation

[0040] The present invention will now be further described based on preferred embodiments and with reference to the accompanying drawings.

[0041] For ease of understanding, various components on the drawings have been enlarged or reduced, but this is not intended to limit the scope of protection of this invention.

[0042] In the description of the embodiments of this invention, it should be noted that if terms such as "upper," "lower," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this embodiment is in use, they are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, in the description of this invention, in order to distinguish different units, terms such as "first" and "second" are used in this specification, but these are not limited by the manufacturing order, nor should they be construed as indicating or implying relative importance. Their names may differ in the detailed description and claims of this invention.

[0043] The terminology used in this specification is for illustrative purposes and is not intended to limit the invention. It should also be noted that, unless otherwise explicitly stated and limited, the terms "set," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, a direct connection, or an indirect connection via an intermediate medium; or they can refer to the internal communication between two components. Those skilled in the art will understand the specific meaning of these terms in this invention.

[0044] As analyzed in the background section, to effectively dissipate heat from a motor, an axially continuous air exchange channel (airflow path) can be incorporated inside the motor. An axial fan or similar device drives external airflow through the motor's interior to remove the heat generated during rotation. For example, Chinese invention patent CN103607073 provides a high-efficiency cooling motor with a three-airflow structure. However, while this structure improves heat dissipation, it also allows external dust and sand particles to enter the motor, causing corrosion. These problems become more pronounced when used outdoors or in harsh environments.

[0045] To address the aforementioned problems, embodiments of the present invention provide a dust-removing and cooling motor. This motor includes a motor shaft, a rotor structure, a stator structure, and a motor housing. The rotor structure has an axially penetrating heat exchange channel. Furthermore, the motor includes a dust-removing and flow-guiding structure. This structure is configured such that, based on the rotation of the motor shaft, a portion of the airflow entering the motor rotates circumferentially and exits the motor, while the remaining portion flows out of the motor from one end of the heat exchange channel near the dust-removing and flow-guiding structure and then from the other end away from the structure. The motor provided by this invention utilizes the rotation of the motor shaft to first remove dust from the gas entering the motor through the dust-removing and flow-guiding structure. This ensures that impurities such as sand and stones are removed from the motor before the airflow passes through it, thereby avoiding potential damage to the motor caused by impurities in the gas when using the heat exchange channel for motor cooling.

[0046] <Motor Structure>

[0047] The dust-removing and cooling motor provided by the present invention will be described in detail below with reference to the accompanying drawings.

[0048] Figure 1 , Figure 2 The images show schematic diagrams and top views of a dust-removing and cooling motor provided in some embodiments of the present invention. Figure 3A and Figure 3B These are its exploded view and front view, respectively. Figure 4A and Figure 4B These are its half-section view and sectional view (the cutting lines are respectively) Figure 2 (AA and BB lines in the figure). As shown in the figures above, the motor includes a motor housing 1, and a stator structure, a rotor structure 3, a motor shaft 4 (one end of the motor shaft extends out of the motor housing 1 to drive the components connected thereto), and a dust removal and guiding structure disposed inside the motor housing 1.

[0049] The shape of the motor housing 1 can be designed according to the dimensions and fit of the aforementioned parts. For ease of installation and maintenance, it is generally designed to be detachably fixed. For example, it can be composed of an upper cover 11, a cylindrical motor housing 12 and a lower cover 13, as shown in the figures above. They can be fixed to each other by screws and nuts, clips or other methods known to those skilled in the art, and can be easily disassembled during the installation of internal equipment and maintenance.

[0050] As shown in the figures above, the stator structure is fixedly connected to the inner wall of the motor housing 1. It includes a stator core 21 and multiple sets of circumferentially distributed windings 22 wound on the stator core 21. The stator windings can be connected in a DC drive or AC drive manner and connected to the power supply through a connector not shown in the figure.

[0051] The rotor structure 3 is located inside the stator structure and consists of several magnets with alternating magnetic poles along the circumferential direction. The motor shaft 4 is coaxially arranged with the rotor structure 3, with its middle part fixed inside the rotor structure 3. The parts protruding from the rotor structure 3 on both sides can be housed in the motor housing through the upper bearing 51 and the lower bearing 52. After applying DC or AC current to the motor, it can rotate around its axis relative to the motor housing, and the speed can be adjusted under the control of the control unit or frequency converter (not shown in the figure).

[0052] One end of the motor shaft 4 extends out of the motor housing 1 and can be connected to the driven component by key 41. In addition, the motor housing 1 also includes an upper bearing cover 14 and a lower bearing cover 15 for limiting and pre-tightening the upper bearing 51 and the lower bearing 52. Obviously, the upper bearing cover 14 is also provided with a through hole for the motor shaft 4 to pass through.

[0053] The structures and assembly methods of the above-mentioned parts are all common designs known to those skilled in the art. Any adjustments or replacements made to the above-mentioned structures and components based on the specific usage environment and design specifications without departing from the technical concept of this invention should be covered within the protection scope of this invention.

[0054] In order to effectively cool the motor during operation, such as Figure 4A and Figure 4B As shown, at least one heat exchange channel 31 is provided on the rotor structure 3 through the rotor structure 3. When the number of heat exchange channels is greater than two, they can be arranged circumferentially to introduce relatively low-temperature airflow from outside the motor and discharge the airflow from the motor after absorbing heat exchange inside the motor.

[0055] Obviously, in order to achieve airflow exchange between the inside and outside of the motor, at least one airflow inlet and at least one airflow outlet need to be provided on the motor housing 1. Specifically, in the embodiments shown in the above figures, the motor includes at least one airflow inlet 16, which is located on the upper part of the motor housing 1, that is, on the side of the motor housing 1 through which the motor shaft 4 passes. For example, as shown in the above figures, multiple airflow inlets 16 can be distributed circumferentially at intervals on the upper cover 11 and pass through the upper cover 11 to form a channel for airflow to enter the motor.

[0056] Meanwhile, the motor housing 1 of the motor has at least one first airflow outlet 171 so that the airflow after heat exchange can flow out of the motor.

[0057] It should be noted that, in the embodiments of the present invention, the airflow after heat exchange refers to the gas that flows in from the end of the heat exchange channel 31 near the airflow inlet 16 and then flows out from the end of the heat exchange channel 31 away from the airflow inlet 16. As shown in the figures above, at least one first airflow outlet 171 can be provided on the side of the cylindrical motor housing 12 away from the airflow inlet 16, or one or more first airflow outlets 171 can be provided on the lower cover 13 to form a channel for the airflow that flows through the heat exchange channel 31 and is discharged from the motor after heat exchange.

[0058] Furthermore, in order to drive the airflow through the heat exchange channel 31 to remove the heat inside the motor, and at the same time avoid the influence of impurities in the airflow entering the motor from the outside of the motor on the internal structure of the motor during this heat exchange process, in the embodiments shown in the above figures, the interior of the dust-removing and cooling motor is also provided with a dust removal and airflow guiding structure.

[0059] In some preferred embodiments, such as Figure 3A and Figure 4A , Figure 4B As shown in the figures, the dust removal and flow guiding structure includes a centrifugal impeller 6 and at least one second airflow outlet 172 disposed on the motor housing. Based on the rotation of the motor shaft 4, this dust removal and flow guiding structure can guide a portion of the airflow flowing into the motor to rotate circumferentially and exit the motor through the second airflow outlet 172, and guide the remaining portion of the airflow from the end of the heat exchange channel 31 near the dust removal and flow guiding structure, through the end away from the dust removal and flow guiding structure, and then exit the motor through the first airflow outlet 171.

[0060] Figure 5A The three-dimensional structure of the centrifugal impeller 6 is shown in some embodiments of the present invention. Figure 5B This is a top view of the centrifugal impeller 6. Figure 5C and Figure 5D The impeller 6 was cut and shown from different perspectives, with the cutting lines being... Figure 5B The DD line in the middle.

[0061] Referring to the figures above, in this embodiment of the invention, the centrifugal impeller 6 is axially disposed between the airflow inlet 16 and the rotor structure 3, and includes a front disc 61, a rear disc 62, and several blades 63 arranged sequentially from the upper cover 11 to the lower cover 13 along the axial direction. The front disc 61 is annular and coaxially disposed with the motor shaft 4. The rear disc 62 has a motor hole 42 through which the motor shaft 4 passes, and is coaxially fixedly connected to the motor shaft 4 by means of key connection or interference fit. Several blades 63 are fixedly disposed circumferentially between the front disc 61 and the rear disc 62. When the motor is in operation, the centrifugal impeller 6, driven by the motor shaft 4, drives the airflow flowing into the motor to rotate centrifugally, and forms a circumferential rotating airflow under the constraint of the motor housing 1.

[0062] The second airflow outlet 172 is located at the position where the motor housing contacts the circumferential rotating airflow, serving to form a channel for a portion of the circumferential rotating airflow to exit the motor. For example, it can be like... Figure 4A , Figure 4B As shown, a second airflow outlet 172 is opened on the side wall of the upper cover 11 at a position that is basically consistent with the axial height of each blade 63 of the centrifugal impeller 6.

[0063] In some preferred embodiments, the inner wall of the motor housing 1, particularly the inner wall of the motor housing 12, is provided with an inwardly tapered frustum structure 18. The frustum structure 18 can be integrally formed with the motor housing 12, or it can be fixedly connected to the inner wall of the motor housing 12 by means of bonding, welding, etc. As shown in the figure, its position is located below the second airflow outlet 172, and the part where it is joined with the inner wall of the motor housing 12 is rounded or chamfered, thereby guiding the remaining part of the circumferential rotating airflow into the heat exchange channel 31.

[0064] <Dust Removal and Cooling Process>

[0065] The following combination Figure 5E and Figure 5F This section details the working process of the dust-removing and cooling motor.

[0066] After the motor is powered on, the rotor structure 3 and the motor shaft 4 rotate relative to the stator structure. Driven by the rotor structure, the centrifugal impeller 6 rotates, causing the external airflow 81 to enter the motor through the airflow inlet 16. The airflow 81 is then driven by the centrifugal impeller 6 to flow toward the inner wall of the motor housing 1. Under the constraint of the inner wall, an airflow rotating in the circumferential direction is formed (i.e., the circumferential rotating airflow 82 in the figure). At this time, impurities such as sand and dust in the airflow are gradually thrown to the outer layer of the circumferential rotating airflow 82 under the action of centrifugal force. When the circumferential rotating airflow 82 flows to the second airflow outlet 172, a part of it will flow out of the motor in a circumferential rotation through the second airflow outlet 172, forming the ejection airflow 83. At the same time, the impurities 9 in the circumferential rotating airflow 82, after losing the constraint of the inner wall of the motor housing 1, are thrown out of the motor housing 1 along with this part of the ejection airflow 83, thereby realizing the dust removal operation of the airflow flowing into the motor from the outside.

[0067] As the centrifugal impeller 6 rotates continuously, the external airflow 81 continuously enters the motor. In addition to the ejected airflow 83 that flows out of the motor through the second airflow outlet 172, the remaining part of the circumferential rotating airflow 82 will gradually flow downward along the axial direction, flowing into the rotor structure 3 from the end of the heat exchange channel 31 near the airflow inlet 16 and flowing out of the rotor structure 3 from the end of the heat exchange channel 31 away from the airflow inlet 16 (this part of the airflow is the heat exchange airflow 84). As analyzed above, this part of the heat exchange airflow 84 flows out of the motor through the first airflow outlet 171, thereby carrying away the heat generated by the motor operation from the motor.

[0068] As can be seen, the dust-removing and cooling motor provided by the present invention, through the dust removal and flow guiding structure composed of centrifugal impeller 6, second airflow outlet 172 and axial flow guide 7, can effectively remove impurities in the airflow flowing into the motor and guide the remaining airflow to flow smoothly through the heat exchange channel 31. While ensuring efficient heat dissipation and cooling of the motor, it avoids the influence of impurities in the airflow on the internal structure and operation of the motor.

[0069] Further optimization of this dust-removing and cooling motor.

[0070] As explained above, the motor provided by this invention needs to remove some of the impurities 9 from the airflow entering the motor by throwing away a portion of the airflow. Although the dust removal effect can be improved by increasing the flow rate of the thrown airflow 83, this will inevitably reduce the heat exchange airflow 84 and reduce the efficiency of heat exchange. Obviously, this will reduce the proportion of the additional energy consumed by the motor used for cooling. In addition, during the process of the airflow changing from circumferential rotation to axial flow, although the heat exchange airflow 84 will eventually pass through the heat exchange channel 31 as the airflow accumulates, if it is not efficiently guided, the airflow will generate various irregular turbulence and eddies during the conversion process, causing its kinetic energy to be ineffectively lost. This will inevitably reduce its flow velocity and flow rate through the heat exchange channel 31, resulting in a decrease in the heat carried away per unit of energy consumption. Moreover, the above problems cannot be effectively solved by simply increasing the air intake volume, and may even lead to further aggravation of turbulence and other phenomena, resulting in a further reduction in cost-effectiveness.

[0071] To this end, the present invention also provides several embodiments that optimize the structure of various parts of the motor, such as the air intake, impurity separation, and heat dissipation, to further improve the efficiency of dust removal and cooling. These embodiments are described in detail below with reference to the accompanying drawings.

[0072] A. Optimization of airflow inlet structure

[0073] In some embodiments, such as Figure 1 As shown, Figure 2 As shown, multiple airflow inlets 16 can be arranged around the motor shaft hole of the upper cover 11 in a circumferentially spaced manner. By increasing the number of airflow inlets 16 and circumferentially spaced them, the intake volume of external airflow can be increased.

[0074] In some embodiments, such as Figure 1 or Figure 3A As shown, the side of the upper cover 11 through which the motor shaft 4 passes is shaped to be recessed into the motor. Therefore, the orientation of the airflow inlet 16 (which can be characterized, for example, by the normal direction of the surface formed by the opening area of ​​the airflow inlet 16) will be such that it extends obliquely downwards axially and outwards radially from the axis of the motor shaft 4; that is, the orientation of the airflow inlet 16 on the axial section of the motor (e.g., ...) Figure 4B The projection line of the cross section shown is not parallel to the axis of the motor shaft 4, and the two intersect on the outside of the side of the motor housing that is penetrated by the motor shaft 4.

[0075] refer to Figure 5EAs shown in the figure, setting the opening orientation of the airflow inlet 16 in this way allows the external airflow 81 to enter the motor from the outer periphery of the upper cover 11 in an inclined manner toward the blades 63 of the centrifugal impeller 6. This results in a shorter flow path and smoother driving by the centrifugal impeller, which is beneficial to increase the flow rate and velocity of the circumferential rotating airflow 82 with the same driving energy consumption, and to exert a greater centrifugal force on the impurities 9 contained in the circumferential rotating airflow 82.

[0076] As the motor's speed gradually increases from 0 to the set value during startup, the velocity of the circumferential rotating airflow generated by the centrifugal impeller 6 will also gradually increase. When the velocity is low, it is often difficult to carry the impurities 9 in the airflow out of the second airflow outlet 172. Therefore, in some preferred embodiments, the dust-removing and cooling motor is also provided with an airflow inlet sealing structure at the airflow inlet 16. The airflow inlet sealing structure can be constructed using various electronically controlled opening and closing structures known to those skilled in the art. For example, the motor speed can be monitored by a Hall sensor. When the motor speed is less than the preset dust removal speed threshold, the airflow inlet 16 is sealed by the electronically controlled opening and closing structure to avoid the problem that the velocity of the airflow entering the motor is low and the impurities 9 cannot be thrown out and thus enter the motor.

[0077] The dust removal speed threshold can be determined by testing the internal heat generation of the motor at different speeds and the discharge of impurities 9 through the second airflow outlet 172 in the specific operating environment. Determining the opening timing of the airflow inlet sealing structure in this way ensures that the internal heat generation of the motor is at a low level when the speed is below the dust removal speed threshold, thus not affecting the heat dissipation effect.

[0078] B. Optimization of the centrifugal impeller structure

[0079] In embodiments of the present invention, the centrifugal impeller 6 may be made of a metal material or a polymer material with high hardness. Preferably, a wear-resistant coating may be applied to the surface of the centrifugal impeller 6 to enhance its wear resistance.

[0080] refer to Figures 5A to 5DIn some preferred embodiments, the front disc 61 of the impeller 6 is composed of a first annular region 611 and a first guide structure 612, wherein the first annular region 611 is fixedly connected to one end of each blade 63, and the first guide structure 612 is formed by bending the first annular region 611 radially from the outside to the inside toward the airflow inlet 16. Preferably, the end face 6121 of the first guide structure 612 toward the airflow inlet 16 is parallel to the inner wall of the motor housing 1 (more specifically, the upper cover 11 in the figure) at the airflow inlet 16; the rear disc of the impeller 6 62 is constructed in a roughly bowl-shaped form, including a second annular region 621 and a part fixedly connected to the motor shaft 4. The second annular region 621 is fixedly connected to the other end of each blade 63. The part fixedly connected to the motor shaft 4 can gradually shrink from front to back along the axial direction of the second annular region 621 to form a concave bowl-shaped connecting part 622. The bottom of the connecting part 622 has a motor hole 42. The motor shaft 4 passes through the motor hole 42 and is fixedly connected to the connecting part 622 by means of key connection or interference fit.

[0081] In some preferred embodiments, such as Figures 5A to 5D As shown, the first annular region 611 and the second annular region 621 are arranged horizontally or approximately horizontally along the radial direction at the outlet of the blade 63. With this structural arrangement, the centrifugal airflow channel formed by the front disc 61 and the rear disc 62 of the centrifugal impeller 6 gradually contracts from the inside to the outside along the radial direction, and then forms a horizontal radial channel with a constant width or a horizontal radial channel with a relatively slow expansion. This can effectively prevent the external airflow 81 from generating axial velocity after entering the housing 1, causing it to directly become the heat exchange airflow 84 without going through the dust removal and filtration process of the second airflow outlet 172.

[0082] In some preferred embodiments, the maximum diameter of the second annular region 621 is less than or equal to the maximum diameter of the first annular region 611. Reducing the maximum diameter of the second annular region 621 can expand the flow channel of the heat exchange airflow 84 after dust removal, and further reduce flow loss.

[0083] To maximize the utilization of the airflow entering the motor and shorten the radial guidance path (this shortening of the guidance path is particularly beneficial for reducing the power consumption of the motor driving the centrifugal impeller 6, i.e., avoiding excessive energy loss to the drive load due to excessive energy consumption by the motor for heat dissipation), the width of the front plate 61 can be set narrower and its position as outward as possible. For example, it can be like... Figures 5A to 5DAs shown, the outer diameter of the front disc 61, the maximum radial distance of the first annular region 611 is greater than the maximum radial distance of each airflow inlet 16; the inner diameter of the front disc 61, i.e., the minimum radial distance of the first guide structure 612, is not less than 90% of the maximum radial distance of each airflow inlet 16. With this arrangement, the airflow entering the motor through the airflow inlet 16 can form a circumferential rotating airflow more quickly, effectively reducing the power consumption of the motor driving the centrifugal impeller 6.

[0084] In some preferred embodiments, such as Figures 5A to 5D As shown, the rear disc 62 also includes a second flow guide structure 623, which can be formed by protruding inward at the junction of the second annular region 621 and the connecting portion 622, and its shape is set to bend radially from the outside to the inside toward the airflow inlet 16.

[0085] In some preferred embodiments, the inner diameter of the second flow guiding structure 623 is larger than the inner diameter of the airflow inlet 16, but smaller than 1.1 times the inner diameter of the airflow inlet 16. In other preferred embodiments, the end face 6231 of the second flow guiding structure 623 facing the airflow inlet 16 can be set to be parallel to the inner wall of the motor housing 1 (more specifically, the upper cover 11 in the figure) at the airflow inlet 16. Through the above structural optimization, the inner diameter of the second flow guiding structure 623 can be limited to between 1 and 1.1 times the inner diameter of the airflow inlet 16, so as to better receive the external airflow 81 entering the housing 1 at the edge of the airflow inlet 16, so that it can be better guided along the path, and to avoid it entering the bowl-shaped bottom space of the connecting part 622 as much as possible.

[0086] During the rotation of the centrifugal impeller 6 relative to the motor housing 1 as the motor shaft 4 rotates, its front disc 61 and rear disc 62 must maintain a certain distance from the inner wall of the motor housing 1 to avoid contact with it. Specifically, in Figure 4A , Figure 4B and 5A to Figure 5D In the embodiment shown, the minimum distances between the front disc 61, the rear disc 62 and the inner wall of the motor housing 1 are the distances between the end face 6121 of the first flow guiding structure 612 and the end face 6231 of the second flow guiding structure 623 and the lower surface of the upper cover 11, respectively.

[0087] During motor rotation, a "gas barrier" formed by flowing air can be formed between end face 6121, end face 6231 and the lower surface of the upper cover 11 to block impurities 9 from passing through. The blocking effect of the "gas barrier" increases with the increase of motor speed. Therefore, in some preferred embodiments, the minimum distance can be increased with the increase of motor rated speed, thereby further reducing the amount of material used in the front disc 61 and the rear disc 62 and reducing the weight of the centrifugal impeller 6.

[0088] At the same time, it should be noted that the minimum distance mentioned above cannot be increased indefinitely. This is because when the distance between end face 6121 or end face 6231 and the lower surface of the upper cover 11 exceeds a certain limit, the "gas barrier" effect will be drastically reduced. Therefore, preferably, a preset distance threshold can be set. The minimum distance between the front disc 61 or rear disc 62 and the inner wall of the motor housing 1 increases to the preset distance threshold as the rated speed of the motor increases, and then no longer increases.

[0089] See Figures 5A to 5D Multiple blades 63 are circumferentially spaced between the front plate 61 and the rear plate 62, and each blade 63 has an airfoil profile. The orientation of the blades 63 can be adjusted according to the rotation direction of the motor, for example, Figures 5A to 5D The centrifugal impeller 6 shown is suitable for a motor that can rotate in both directions. In order to ensure the same airflow guiding effect when rotating in both directions, the blade 63 adopts a radial centrifugal blade, that is, its leading edge to trailing edge does not bend forward or backward in a certain direction of rotation. At this time, the center line of the profile of each cross section of the blade 63 is a straight line and passes through the axis of the motor shaft 4.

[0090] In addition, when the motor is a unidirectional rotating motor, it can also be like... Figures 5G to 5H As shown, backward centrifugal blades are used as blades 63 to further enhance the aerodynamic effect of the centrifugal impeller 6 when the motor rotates in one direction.

[0091] In some preferred embodiments, in order to maximize the effective work of the blade within the same space and size, blades with different airfoils at different cross-sections can be used. For example, the chord length of the airfoil at the blade 63 cross-section can gradually increase from the front disk 61 to the rear disk 62. Alternatively, the outer diameter of the blade at the front disk 61 can be larger than the outer diameter of the blade at the rear disk 62, and the inner diameter of the blade at the front disk 61 can be larger than the inner diameter of the blade at the rear disk 62, thereby causing the blade at the rear disk 62 to tilt radially inward. Furthermore, the blade 63 can adopt a relatively short and thick non-standard airfoil, and the ratio of the thickness to the chord length of each cross-section airfoil can be set between 15% and 42%. By increasing the maximum thickness of the airfoil, both aerodynamic and strength requirements can be met simultaneously, while reducing noise.

[0092] C. Optimization of the second airflow outlet structure

[0093] In addition to the structure of the centrifugal impeller 6, the structure of the second air outlet 172 also has a significant impact on the discharge effect of impurities 9. This is because impurities 9 can only be thrown out of the motor if they have moved a radial distance sufficient to pass through the motor housing 1 during their passage through the second air outlet 172.

[0094] See Figure 6AIn the embodiment shown, the circumferential length of the second airflow outlet 172 is L, and the radial height is H (see [reference]). Figure 3B The thickness of the impurity 9 at both ends is T. When the circumferential rotating airflow 82 moves to the cut-in airflow outlet, the impurity 9 will break free from the constraint of the inner wall of the motor housing 12 and be thrown out radially. At the same time, it will also fall downward under the action of gravity. It can be seen that only when the impurity 9 moves radially beyond T and falls radially less than H during the process of passing through L in the circumferential direction (assuming that the impurity 9 is at the highest point of the outlet when it enters the area of ​​the second airflow outlet 172), can it be thrown away from the motor.

[0095] Obviously, the faster the impurity 9 rotates, the greater its radial speed, but at the same time, its circumferential speed is also greater, resulting in a shorter time for it to pass through the second airflow outlet in the circumferential direction. Therefore, although the length of L can be increased to ensure that more impurities 9 are discharged through the second airflow outlet 172, this will also cause more circumferential rotating airflow 82 to be thrown out to form jet airflow 83, reducing the portion used for cooling (heat exchange airflow 84). Therefore, simply increasing the rotational speed or increasing the length of the second airflow outlet 172 cannot simultaneously improve the discharge effect of impurities 9 and retain more heat exchange airflow 84 for motor cooling.

[0096] Therefore, in some preferred embodiments, the minimum circumferential length and the minimum axial height of the second airflow outlet 172 can be determined based on the rated speed of the motor and the thickness of the motor housing 1 at the second airflow outlet 172.

[0097] For example, the structure of the second airflow outlet 172 can be optimized through the following steps:

[0098] First, based on the rated speed of the motor, determine the speed at which the impurity 9 moves circumferentially under the influence of the circumferential rotating airflow 82 and the constraint of the inner wall of the motor housing 1. Generally, the motor speed and the speed of the impurity 9 can be determined by actual measurement or simulation. The volume, weight, and other parameters of the impurity 9 can be obtained by sampling the components such as sand and dust in the actual use environment.

[0099] Then, based on the movement speed of impurity 9, the time required for it to pass radially through the shell with a wall thickness of H, the length of the circumferential movement during this time, and the height of the axial fall are estimated. Then, the length of the circumferential movement and the height of the axial fall are used as the minimum values ​​of the circumferential length and the minimum value of the axial height of the second airflow outlet 172.

[0100] By optimizing the length and height of the second air outlet 172 using the above steps, it is possible to minimize the ratio of jet airflow 83 to heat exchange airflow 84 while ensuring that impurities 9 are just discharged.

[0101] In some other preferred embodiments, the motor housing 1 can be configured as a structure with unequal thickness, for example, like... Figure 6B and Figure 6C As shown in the embodiment, the wall thickness at the second air outlet 172 is set to a minimum value T", and then gradually increases circumferentially to both sides, eventually reaching a preset thickness (e.g., T'). That is, most of the area of ​​the motor housing 1 has an equal wall thickness T', gradually thinning near the second air outlet 172, and finally having the thinnest thickness T" at the outlet. In this way, the overall strength of the motor housing 1 can be guaranteed, and the radial movement distance required for the discharge of impurities 9 at the second air outlet 172 can be reduced, thereby reducing the circumferential length of the second air outlet 172 to L'. While achieving the same impurity 9 discharge effect, the amount of ejected airflow 83 flowing out through the second air outlet can be further reduced.

[0102] Obviously, when the motor is a unidirectional motor, it can also be like... Figure 6D As shown, the wall thickness of the motor housing 1 is minimized at one end (facing the circumferentially rotating airflow) at the second airflow outlet 172, and then gradually increases to T' along the circumferential direction of airflow rotation, while maintaining a wall thickness of T' at the other end of the second airflow outlet 172.

[0103] D. Optimization of axial flow guidance structure

[0104] To better guide the circumferentially rotating heat exchange airflow 84 smoothly into the heat exchange channel 31, in some preferred embodiments, such as... Figure 7 As shown, the dust removal and airflow guiding structure also includes an axial flow guiding section 7, which guides the remaining portion of the circumferential rotating airflow that does not exit the motor through the second airflow outlet 172 (i.e., the heat exchange airflow 84) ​​into the heat exchange channel 31, such as... Figures 8A to 8C As shown, in some embodiments of the present invention, the axial flow guide 7 includes a conical annular flow guide ring 71. The flow guide ring 71 is coaxially disposed between the circumferential rotating airflow and the heat exchange channel 31 and the motor shaft 4, and is fixedly connected to the inner wall of the motor housing 1. Its radius gradually shrinks from front to back along the axial direction, that is, it gradually shrinks from the centrifugal impeller 6 to the rotor structure 3 in the axial direction.

[0105] In some preferred embodiments, the conical surface of the guide ring 71 is tangent to the inner surface of the stator winding 22 to facilitate guiding the heat exchange airflow 84 into the heat exchange channel 31 and to prevent the heat exchange airflow 84 from entering the outside of the stator winding 22 and exhausting the kinetic energy of this airflow.

[0106] In order to ensure that the axial flow guide 7 can be firmly fixed to the inner wall of the motor housing 1, in some embodiments, the axial flow guide 7 further includes a planar annular support 72. The plane of the support 72 can be perpendicular or nearly perpendicular to the axis of the motor shaft 4. It can be fixedly connected to the flow guide ring 71 by welding, bonding or other means, and then the axial flow guide 7 is firmly fixed to the inner wall of the motor housing 1 by mutually matching bolts-screw holes or other fixing methods.

[0107] It should be understood that the fixed connection between the axial flow guide 7 and the motor housing 1 shown in the above figures is only illustrative. Those skilled in the art can also choose other fixing methods without departing from the technical concept. In addition, besides the separately provided flow guide ring 71, the structure of the flow guide ring 71 can also be formed directly on the inner wall of the motor housing 1 by thickening or stretching the inner wall of the motor housing 1. Obviously, in this case, there is no need to provide a support part for fixing.

[0108] As the centrifugal impeller 6 continuously introduces external airflow into the motor, with the increase of airflow pressure, the heat exchange airflow 84 retained inside the motor will continuously move downward along the axis during the circumferential rotation and enter the heat exchange channel. During this process of conversion from circumferential to axial motion, if the heat exchange airflow 84 is not guided axially, its rotational kinetic energy will gradually decrease, and it will eventually be passively pushed into the heat exchange channel by the gradually increasing wind pressure. This not only wastes the original kinetic energy of the airflow, but also results in a low airflow velocity in the heat exchange channel and poor heat exchange efficiency.

[0109] For this purpose, several axial flow channels can be provided circumferentially on the side of the flow guide ring 71 facing the airflow inlet 16 to guide the remaining part of the circumferential rotating airflow 82 (i.e., the heat exchange airflow 84) ​​axially into the heat exchange channel 31.

[0110] In some embodiments, such as Figures 8A to 8C As shown, multiple plate-shaped axial guide teeth 73 can be spaced out on the guide ring 71, forming an axial guide channel between every two axial guide teeth 73. Through the axial guide channel, the circumferentially rotating heat exchange airflow 84 will be guided to flow axially downward into the heat exchange channel 31 at a higher flow rate, thereby effectively utilizing the original kinetic energy of the airflow and improving the heat exchange efficiency.

[0111] Figure 9A and Figure 9B The following diagrams illustrate the airflow velocity distribution inside the motor in some embodiments, with and without the axial flow guide 7 in the dust removal guide structure. Figure 9A and Figure 9BIt can be seen that after adding the axial guide section, the airflow changes more smoothly during the process of circumferential rotation to axial flow, with no obvious gas accumulation. Moreover, the airflow velocity in the heat exchange channel is significantly improved, and its heat exchange efficiency is significantly increased. This indicates that the airflow after filtering impurities can flow smoothly and at high speed through the heat exchange channel, effectively improving the heat exchange efficiency and reducing the energy consumption ratio of motor cooling.

[0112] Figures 8A to 8C In the illustrated embodiment, since the guide teeth 73 adopt a plate-like structure of equal thickness, the width of each axial guide channel remains consistent along the axial direction. In other embodiments, the width of the axial guide channel can also be set to be variable along the axial direction. For example, the guide teeth 73 with unequal thickness structure can be adopted, with one end facing the airflow inlet 16 being thicker and the other end being thinner, so that the channel width of the axial guide channel facing the airflow inlet 16 is smaller than the channel width facing the heat exchange channel 31. With such a variable width axial guide channel, violent collisions that cause turbulence and thus loss of flow energy can be avoided when the circumferentially rotating airflow enters the axial guide channel.

[0113] E. Optimization of heat exchange structure

[0114] Figure 10A and Figure 10B The figures shown are a perspective view and a side view of the rotor structure 3 provided according to some embodiments. Figure 10C This is a cross-sectional view of rotor structure 3, with the cutting line being... Figure 10B The EE line in the diagram. (e.g.) Figure 10C As shown, the heat exchange channel preferably includes two pipe diameters, namely Figure 10C Multiple heat exchange channels 31 with relatively large pipe diameters and heat exchange channels 31' with relatively small pipe diameters are used. The radial distance between the heat exchange channel 31 with a larger pipe diameter and the motor shaft 4 is smaller than the radial distance between the heat exchange channel 31' with a smaller pipe diameter and the motor shaft 4. By using heat exchange channels with different pipe diameters, the heat exchange area can be expanded by making full use of the limited space, and the heat exchange airflow 84 can be utilized more fully.

[0115] As the rotor structure 3 rotates, the heat exchange airflow 84 flowing out through the heat exchange channel 31 or heat exchange channel 31' is thrown out radially. Therefore, in some preferred embodiments, the distance between the first airflow outlet 171 and the motor shaft 4 is greater than or equal to the distance between the heat exchange channel 31 and the heat exchange channel 31' and the motor shaft. For example, it can be like... Figure 1 As shown in the figures, the first airflow outlet 171 is disposed on the side wall of the motor housing 12.

[0116] Furthermore, preferably, such as Figure 1As shown in the figures, a guide hood 32 can also be provided between the end of the heat exchange channel away from the dust removal guide structure and the first airflow outlet 171 to guide the heat exchange airflow 84 to flow out of the first airflow outlet 171 more smoothly.

[0117] This invention also provides a design method for designing the aforementioned dust-removing and cooling motor, such as... Figure 11 As shown, the method includes the following steps:

[0118] The first step is to analyze the composition of gaseous impurities in the environment in which the motor is used.

[0119] Specifically, the gas in the operating environment of the motor can be sampled and analyzed to obtain the volume and weight statistical characteristics of the impurity components contained therein, as well as parameters such as the volume or weight percentage in the ambient gas.

[0120] The second step is to design the dust removal and flow guiding structure of the motor based on the analysis results of gas impurity composition and the rated speed of the motor.

[0121] Specifically, the dust removal guide structure is designed based on the rated speed of the motor and the impurity composition analysis results obtained in the first step, including the shape of the centrifugal impeller 6 and the axial guide 7 and the position of the second airflow outlet 172, so as to ensure that when the external airflow 81 enters the motor at the rated speed of the motor, it can form a circumferential rotating airflow 82 that effectively discharges impurities 9.

[0122] Preferably, the dimensions of the second air outlet 172 can be further optimized based on the situation where the motor drives the centrifugal impeller 6 to rotate at the rated speed and the analysis results of the gas impurity composition. For example, the minimum values ​​of the circumferential length and axial height of the second air outlet 172 can be determined by using the steps described above, so that the impurities 9 are just discharged while minimizing the ratio of the jetting airflow 83 to the heat exchange airflow 84.

[0123] The specific embodiments of the present invention have been described in detail above. For those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A dust-removing and cooling motor, comprising a motor shaft, a rotor structure, a stator structure, and a motor housing, wherein the rotor structure is provided with an axially penetrating heat exchange channel, and the motor housing has an airflow inlet on one side through which the motor shaft passes, and a first airflow outlet on the side away from the airflow inlet, characterized in that, It also includes a dust removal and flow guiding structure, configured to guide a portion of the airflow flowing into the motor to circumferentially rotate out of the motor based on the rotation of the motor shaft, and to guide the remaining portion from one end of the heat exchange channel near the dust removal and flow guiding structure to the other end away from the dust removal and flow guiding structure, and out of the motor through the first airflow outlet.

2. The dust-removing and cooling motor according to claim 1, characterized in that, The dust removal and flow guiding structure includes: A centrifugal impeller is axially disposed between the airflow inlet and the rotor structure, and is used to drive the airflow flowing into the motor to rotate centrifugally under the drive of the motor shaft, and to form a circumferential rotating airflow under the constraint of the motor housing; The second airflow outlet is located at the position where the motor housing contacts the circumferential rotating airflow, and is used to form a channel through which a portion of the circumferential rotating airflow flows out of the motor; An axial flow guide is used to guide the remaining portion of the circumferential rotating airflow into the heat exchange channel.

3. The dust-removing and cooling motor according to claim 2, characterized in that, The number of airflow inlets is greater than or equal to two, and they are arranged circumferentially around the motor shaft holes on the motor housing.

4. The dust-removing and cooling motor according to claim 2, characterized in that, The projection line of the airflow inlet onto the axial section of the motor is not parallel to the axis of the motor shaft, and the two intersect at the outside of the motor housing on one side that penetrates the motor shaft.

5. The dust-removing and cooling motor according to claim 2, characterized in that, It also includes an airflow inlet sealing structure, used to seal the airflow inlet when the speed of the motor is less than the dust removal speed threshold.

6. The dust-removing and cooling motor according to claim 2, characterized in that, The centrifugal impeller includes: The annular front disc is coaxially arranged with the motor shaft. The rear plate is coaxially arranged with the motor shaft and fixedly connected to the motor shaft; Several blades are fixedly arranged circumferentially between the front and rear discs.

7. The dust-removing and cooling motor according to claim 6, characterized in that, The width of the centrifugal airflow channel formed by the front and rear discs either contracts radially from the inside out and then remains constant, or contracts and then expands.

8. The dust-removing and cooling motor according to claim 7, characterized in that, The outer diameter of the front disc is greater than the maximum radial distance of the airflow inlet, and the inner diameter is not less than 90% of the maximum radial distance of the airflow inlet.

9. The dust-removing and cooling motor according to claim 6, characterized in that, The front disc includes: A first annular region fixedly connected to the blade, and a first guide structure that bends radially from the outside to the inside toward the airflow inlet.

10. The dust-removing and cooling motor according to claim 6, characterized in that, The rear disc includes: The second annular region fixedly connected to the blade, and, The portion fixedly connected to the motor shaft, wherein the portion of the rear disc fixedly connected to the motor shaft has a concave shape that gradually tapers from front to back along the axial direction.

11. The dust-removing and cooling motor according to claim 10, characterized in that, The rear disc also includes: A second flow guide structure that bends radially from the outside in toward the airflow inlet.

12. The dust-removing and cooling motor according to claim 6, characterized in that, The minimum distance between the front or rear disc and the inner wall of the motor housing increases with the increase of the rated speed of the motor until a preset distance threshold is reached.

13. The dust-removing and cooling motor according to claim 6, characterized in that, The blades have an airfoil profile.

14. The dust-removing and cooling motor according to claim 6, characterized in that, The blade is a radial centrifugal blade or a backward centrifugal blade.

15. The dust-removing and cooling motor according to claim 14, characterized in that, The ratio of the thickness to the chord length of each airfoil section of the blade is 15% to 42%.

16. The dust-removing and cooling motor according to claim 6, characterized in that, The inner wall of the motor housing is provided with an inwardly tapering frustum structure to guide the remaining portion of the circumferential rotating airflow into the heat exchange channel.

17. The dust-removing and cooling motor according to claim 2, characterized in that, The minimum circumferential length and minimum axial height of the second air outlet are determined based on the rated speed of the motor and the wall thickness of the motor housing at the second air outlet.

18. The dust-removing and cooling motor according to claim 2, characterized in that, The wall thickness of the motor housing gradually increases from the second airflow outlet along the circumferential direction to one or both sides until it reaches the preset thickness.

19. The dust-removing and cooling motor according to claim 2, characterized in that, The dust removal and flow guiding structure also includes an axial flow guiding section; The axial flow guide includes a conical flow guide ring, which is coaxially arranged with the motor shaft and fixedly connected to the inner wall of the motor housing. Its radius gradually decreases from front to back along the axial direction.

20. The dust-removing and cooling motor according to claim 19, characterized in that, The guide ring has several axial guide channels arranged circumferentially on the side facing the airflow inlet, which are used to guide the remaining part of the circumferential rotating airflow axially into the heat exchange channel.

21. The dust-removing and cooling motor according to claim 20, characterized in that, The width of the axial flow channel remains consistent along the axial direction; or, The width of the axial flow channel facing the airflow inlet is smaller than the width of the channel facing the heat exchange channel.

22. The dust-removing and cooling motor according to claim 1, characterized in that, The rotor structure is fixedly connected to the motor shaft, and, The stator structure is fixedly connected to the motor housing.

23. The dust-removing and cooling motor according to claim 1, characterized in that, The number of heat exchange channels is greater than one.

24. The dust-removing and cooling motor according to claim 23, characterized in that, The heat exchange channel includes two pipe diameters, wherein the distance between the heat exchange channel with the larger pipe diameter and the motor shaft is less than the distance between the heat exchange channel with the smaller pipe diameter and the motor shaft.

25. The dust-removing and cooling motor according to claim 1, characterized in that, The distance between the first airflow outlet and the motor shaft is greater than or equal to the distance between the heat exchange channel and the motor shaft.

26. The dust-removing and cooling motor according to claim 25, characterized in that, A flow guide hood is provided between the end of the heat exchange channel away from the dust removal and flow guide structure and the first airflow outlet.

27. A design method for designing a dust-removing and cooling motor as described in any one of claims 1 to 26, characterized in that, Includes the following operations: The first step is to analyze the composition of gaseous impurities in the environment in which the motor is used; The second step is to design the dust removal and flow guiding structure of the motor based on the analysis results of gas impurity composition and the rated speed of the motor.

28. The design method according to claim 27, characterized in that, The dust removal guide structure for the motor, designed based on the analysis results of gas impurity composition and the rated speed of the motor, includes: Based on the situation where the motor drives the centrifugal impeller to rotate at the rated speed, and the analysis results of the gas impurity composition, the size of the second airflow outlet is optimized.

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