Cooling structure for stator and rotor of compressor motor

Abstract

The utility model discloses a compressor motor stator and rotor cooling structure, which comprises a rotor in interference fit with a crankshaft and an oil suction pipe inserted into an inner hole of the crankshaft and contacted with refrigerant oil, the crankshaft is radially provided with a crankshaft oil outlet hole penetrating through the inner hole wall of the crankshaft, and the bottom of the rotor is provided with a rotor oil inlet hole communicated with the crankshaft oil outlet hole. A spiral groove extends in the rotor in the axial direction, the first end of the spiral groove is communicated with the rotor oil inlet hole, and the second end of the spiral groove extends to the outer edge of the upper end face of the rotor. Through the design that the radial-axial communicating structure of the crankshaft oil outlet hole and the rotor oil inlet hole is matched with the axial spiral groove, a closed oil way system generated in the rotating part is formed, and the problems that a traditional external cooling structure is long in heat conduction path and low in heat dissipation efficiency are solved. And direct cooling of a core heating part of the motor is completed in a compact space, so that the working temperature of a winding is reduced by 10-20 DEG C, and the operation reliability and the energy efficiency conversion rate of the motor are remarkably improved.

Description

Technical Field

[0001] This utility model relates to the field of motor oil circuit structure technology, and in particular to a cooling structure for the stator and rotor of a compressor motor. Background Technology

[0002] In the compressor industry, motor temperature has a significant impact on the overall efficiency and reliability of the compressor. This is especially true in high-power commercial compressors, where increased load leads to a marked increase in winding temperature rise, making winding temperature control crucial. Furthermore, the use of lower-cost aluminum wire and the continuous reduction in core size have made excessively high winding temperatures a common occurrence. Traditional compressors lack specific designs for motor cooling, relying primarily on natural cooling of the casing or external fans. Clearly, neither natural cooling nor air cooling can further reduce the motor winding temperature. Therefore, targeted heat dissipation designs are urgently needed to further improve the motor's power density.

[0003] For example, the "Semi-hermetic screw refrigeration compressor with liquid-cooled motor mechanism" disclosed in Chinese patent literature, publication number "CN111120331A", includes a body, a male rotor placed in the body, a motor rotor connected to the long end of the main shaft of the male rotor, and a motor stator that cooperates with the motor rotor; the motor stator is an integral cylindrical structure with a motor stator cavity inside; a gas connector passes through the motor cavity and connects to a through hole at the top of the motor stator cavity; a liquid connector passes through the left end cover and the upper side wall of the motor stator cavity and enters the motor stator cavity; the liquid connector is located on the side wall of the tube body inside the motor stator cavity and connects to a nozzle through a downward hole; multiple heat pipes are fixed to the inner part of the motor stator near the motor rotor through multiple through holes arranged in a radial cross shape, the hot end of the heat pipes extends into the motor stator cavity, and the cold end of the heat pipes is in contact with the outer surface of the motor rotor.

[0004] The above method uses liquid refrigerant injected into the stator cavity of the motor to cool the hot end of the heat pipe, while the cold end of the heat pipe absorbs the heat from the motor rotor, thus cooling the motor. However, the injection range of this method is limited, resulting in uneven cooling areas and unsatisfactory performance, which urgently needs improvement. Utility Model Content

[0005] To address the limited effectiveness of motor cooling methods mentioned in the background section, this invention utilizes a radial-axial interconnected structure between the crankshaft oil outlet and the rotor oil inlet, combined with an axial spiral groove design, to form a closed-loop oil circuit system within the rotating components. This solves the problems of long heat conduction paths and low heat dissipation efficiency inherent in traditional external cooling structures. Direct cooling of the core heat-generating parts of the motor is achieved within a compact space, thereby reducing the winding operating temperature by 10-20°C and significantly improving motor operational reliability and energy conversion efficiency.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A compressor motor stator and rotor cooling structure includes a rotor that is interference-fitted with a crankshaft, an oil suction pipe that is inserted into the inner hole of the crankshaft and in contact with refrigerant oil, the crankshaft having a crankshaft oil outlet hole that penetrates the inner wall of the crankshaft, the rotor having a rotor oil inlet hole at the bottom that communicates with the crankshaft oil outlet hole, and a spiral groove extending axially inside the rotor, the first end of the spiral groove communicating with the rotor oil inlet hole, and the second end extending to the outer edge of the upper end face of the rotor.

[0008] This design utilizes a radial-axial connection between the crankshaft oil outlet and the rotor oil inlet, along with the axial extension of the spiral grooves, to form a closed oil conduction path. When the crankshaft rotates, refrigerant oil enters the crankshaft bore through the suction pipe, is transferred to the rotor interior via the oil outlet, and the spiral grooves guide the oil axially to the outer edge of the rotor's upper end face. This structure utilizes the centrifugal force generated by the rotor's own rotation to achieve directional oil delivery. Compared to traditional external cooling methods, the oil directly contacts the motor core and coil, shortening the heat dissipation path and improving heat transfer efficiency. Furthermore, the rigid, interference-fit connection between the rotor and crankshaft prevents vibration leakage at the oil interface, ensuring stable oil transmission under high-speed rotation.

[0009] Furthermore, the number of crankshaft oil outlet holes is one, two, or several; the crankshaft oil outlet holes are multiple independent channels evenly distributed along the circumference of the crankshaft, and the axis of each channel is inclined relative to the crankshaft axis, and the inclination direction is in the same direction as the rotor rotation direction.

[0010] Furthermore, the outlet end of the crankshaft oil outlet is provided with a guide lip structure extending in the rotor rotation direction.

[0011] Furthermore, the rotor oil inlet includes at least one pair of through holes symmetrically arranged along the rotor axis; the connection between the through holes and the spiral groove forms a flared structure.

[0012] Furthermore, the pitch of the spiral groove gradually decreases along the oil flow direction, and the bottom of the groove is provided with a continuous convex ridge structure extending along the spiral direction.

[0013] Furthermore, the cross-section of the convex ridge structure is triangular, with its apex pointing towards the center line of the spiral groove.

[0014] Furthermore, a spiral guide pattern is provided in the annular gap between the outer wall of the oil suction pipe and the inner hole of the crankshaft, and the spiral direction of the guide pattern is opposite to the rotation direction of the rotor.

[0015] Furthermore, the interference fit surface between the rotor and the crankshaft is provided with an annular oil guide groove, which is connected to the crankshaft oil outlet through a radial connecting hole.

[0016] Furthermore, the number of spiral grooves is one, two, or several, and each spiral groove is uniformly arranged around the inside of the rotor.

[0017] Therefore, this utility model has the following beneficial effects:

[0018] The rotor's interference fit interface and oil passage form a dual-function integration, ensuring power transmission accuracy while simultaneously creating a closed-loop cooling medium channel. The tight fit between the oil suction pipe and the crankshaft inner bore ensures a stable oil supply, and its depth ensures continuous oil suction even under compressor tilting conditions. The spiral groove's strip-shaped outlet creates a specific angled spray trajectory for the oil as it exits the rotor; this angle matches the radial distribution of the stator coil, maximizing the heat dissipation area. During oil circulation, the rotor core's own heat is conducted into the flowing oil film through metal conduction, forming a bidirectional heat dissipation path. Attached Figure Description

[0019] Figure 1 This is a perspective view of the cooling structure in this utility model.

[0020] Figure 2 This is a cross-sectional view of the present invention.

[0021] In the diagram: Rotor 1, Crankshaft 2, Oil suction pipe 3, Annular gap 31, Crankshaft oil outlet 4, Rotor oil inlet 5, Spiral groove 6, Protrusion 61, Annular oil guide groove 7. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0023] Example 1

[0024] like Figure 1 , 2 As shown, a compressor motor stator and rotor cooling structure includes a rotor 1 that is interference-fitted with a crankshaft 2, an oil suction pipe 3 that is inserted into the inner hole of the crankshaft and in contact with refrigerant oil, the crankshaft 2 having a crankshaft oil outlet hole 4 that penetrates its inner hole wall, the rotor 1 having a rotor oil inlet hole 5 at the bottom that communicates with the crankshaft oil outlet hole 4, and a spiral groove 6 extending axially inside the rotor 1, the first end of the spiral groove 6 communicating with the rotor oil inlet hole 5, and the second end extending to the outer edge of the upper end face of the rotor 1.

[0025] The crankshaft oil outlet and rotor oil inlet are radially connected, forming a closed-loop oil circuit with axially extending spiral grooves. When the crankshaft rotates, the refrigerant oil enters through the suction pipe and travels along the oil outlet-inlet path directly into the rotor. The axial extension of the spiral grooves naturally guides the oil to the outer edge as the rotor rotates at high speed. This built-in oil circuit directly targets the core heat-generating parts of the motor, avoiding the problem of excessively long heat conduction paths compared to traditional external cooling structures. Furthermore, the interference-fit rigid connection fundamentally eliminates the risk of oil leakage, making it particularly suitable for the high-speed operation of high-power compressors.

[0026] In this embodiment, the number of crankshaft oil outlet holes 4 is one, but in specific applications, the number is not limited to two or more. The number of rotor oil inlet holes 5 and spiral grooves 6 is also one. In application, depending on the compressor motor specifications and cooling requirements, two or more may be added. Of course, each rotor oil inlet hole 5 or spiral groove 6 is evenly arranged circumferentially around the inside of the rotor. The crankshaft oil outlet holes 4 are multiple independent channels evenly distributed along the crankshaft circumference. The axis of each channel is inclined relative to the crankshaft axis, and the inclination direction is the same as the rotor rotation direction. This layout ensures that the oil has tangential momentum synchronized with the rotor when leaving the crankshaft, significantly reducing kinetic energy loss when the oil enters the rotor. The multi-channel design not only improves oil delivery efficiency but also forms a natural redundancy backup—even if a single channel is temporarily blocked by metal debris, the remaining channels can still maintain more than 70% of the oil delivery volume, which is particularly important for the continuous operation of commercial compressors.

[0027] The crankshaft oil outlet 4 has a guide lip structure extending in the rotor rotation direction at its outlet end. This guide lip structure forms a sharp guiding edge at the end of the oil outlet, its extension direction precisely matching the centrifugal motion trajectory of the oil. Actual tests show that this structure can reduce the turbulence intensity of the oil entering the rotor by approximately 40%, effectively reducing bubbles and oil mist generated by the collision of oil with the metal wall. This smooth transition design is particularly suitable for low-temperature cold start scenarios, enabling the rapid establishment of a stable oil flow during rotor acceleration.

[0028] Furthermore, the rotor oil inlet 5 includes at least a pair of through holes symmetrically arranged along the rotor axis; the connection between the through holes and the spiral groove 6 forms a flared structure. The flared structure creates a progressive flow channel expansion at the junction of the oil inlet and the spiral groove. Utilizing fluid dynamics principles, the oil flow velocity decreases gradually in this region, significantly improving the efficiency of converting kinetic energy into pressure energy. The angle of the flared cone surface is optimized to avoid energy loss caused by flow separation and to compensate for the thermal expansion deformation of the rotor under high-temperature conditions, ensuring long-term sealing of the oil circuit.

[0029] The pitch of the spiral groove 6 gradually decreases along the oil flow direction, and the bottom of the groove is provided with a continuous convex rib 61 extending along the spiral direction. The spiral groove with decreasing pitch forms a dynamic centrifugal force field in the oil travel path. The larger pitch in the first half ensures the basic oil delivery volume, while the gradually narrowing pitch in the second half forces the oil to gather towards the outer edge. This adaptive characteristic allows the oil film coverage area to automatically expand as the rotational speed increases. The continuous convex ribs at the bottom of the groove break the laminar flow boundary, inducing the oil to generate micro-vortices, enhancing the heat exchange efficiency with the metal surface, and improving the uniformity of coil temperature distribution by approximately 30% in actual measurements. The cross-section of the convex rib structure is triangular, with its apex pointing towards the center line of the spiral groove. The convex rib structure enhances the centrifugal effect of the oil while controlling the flow resistance within a reasonable range. Compared to the traditional rectangular cross-section, the triangular convex ribs extend the residence time of the oil in the groove by 20%, fully absorbing rotor heat, while avoiding cavitation caused by excessively high local flow velocities.

[0030] Furthermore, a spiral guide pattern is provided within the annular gap 31 between the outer wall of the oil suction pipe 3 and the inner bore of the crankshaft. The spiral direction of the guide pattern is opposite to the direction of rotor rotation. The reverse spiral guide pattern forms a reverse pressure gradient within the gap of the oil suction pipe. When the rotor rotates at high speed, the reverse shear force generated by the pattern effectively suppresses oil backflow. This characteristic is particularly prominent when the compressor is installed at an angle or under instantaneous start-stop conditions. The precise matching of the spiral direction of the pattern with the direction of rotor rotation ensures that the oil suction pipe can maintain a stable oil supply even under complex operating conditions.

[0031] Furthermore, the interference fit surface between the rotor 1 and the crankshaft 2 is provided with an annular oil guide groove 7, which is connected to the crankshaft oil outlet 4 through a radial connecting hole. The annular oil guide groove forms a continuous oil film lubrication layer on the interference fit surface. The circumferentially distributed connecting holes continuously guide the main oil circuit oil into the gap between the mating surfaces, which reduces the assembly pressing force and avoids fretting wear caused by direct metal-to-metal contact.

[0032] In summary, this embodiment achieves internal circulation cooling of the refrigerant oil through the structural integration of the crankshaft and rotor, by constructing a directional oil passage that runs through the rotating components. The compressor motor rotor and crankshaft are assembled with an interference fit, and the contact surfaces are machined to form a precision fit interface. The oil suction pipe is fixed to the inner bore of the crankshaft and extends below the surface of the refrigerant oil. Several oil outlet holes are radially opened on the crankshaft, with the channels evenly distributed circumferentially and the axial direction forming a specific inclination angle with the plane of rotation. The outlet end is machined with a guide structure. An axial oil inlet hole is provided at a corresponding position at the bottom of the rotor. The inlet of the hole adopts a flared design, forming a smooth transition connection with the internal spiral groove. The spiral groove extends axially along the rotor to the outer edge of the upper end face of the rotor to form a strip-shaped outlet.

[0033] When the compressor is running, the centrifugal force generated by the rotor driving the crankshaft to rotate drives the refrigerant oil to rise along the gap between the oil suction pipe and the inner wall of the crankshaft. After the oil enters the rotor oil inlet through the crankshaft oil outlet, it forms a spiral forward motion under the guidance of the spiral grooves. The spiral grooves continuously enhance the centrifugal force on the oil during its journey, eventually forming a uniform oil film covering the surface of the stator coil from the strip-shaped outlet at the outer edge of the upper end face of the rotor. The structural coordination of each link in the oil passage achieves the progressive conversion of energy: the inclination angle of the crankshaft oil outlet gives the oil an initial tangential velocity, the flared structure of the rotor oil inlet achieves a smooth conversion of kinetic energy into pressure energy, and due to the gradual structure of the spiral grooves, the oil film distribution can be optimized by dynamically adjusting the centrifugal force field.

[0034] In this embodiment, the crankshaft oil outlet corresponds to the rotor oil inlet, ensuring seamless oil circuit connection; the axial extension of the spiral groove converts rotational kinetic energy into directional oil delivery power; the interference fit interface simultaneously performs the dual functions of mechanical transmission and oil circuit sealing. Experimental verification shows that this integrated oil circuit allows the cooling medium to act directly on the core heat-generating area of ​​the motor, significantly shortening the heat conduction path compared to traditional external heat dissipation schemes. The continuous oil film formed on the surface of the stator coil not only achieves contact heat exchange but also carries away accumulated heat through oil flow.

[0035] During compressor startup, the interference fit between the rotor and crankshaft is achieved with zero clearance through a precision press-fit process. During assembly, a temperature difference assembly method is used, employing liquid nitrogen cooling to shrink the crankshaft and heating the rotor to ensure a stable interference connection at room temperature. The oil suction pipe is pressed into the crankshaft bore using a spinning process, with its end immersed to a specific depth below the refrigerant oil surface, forming a stable siphon initiation point. The spatial correspondence between the crankshaft oil outlet and the rotor oil inlet is ensured by specialized positioning fixtures. During assembly, using the rotor keyway as a reference, an optical alignment instrument is used to adjust the crankshaft phase, ensuring a precise radial-axial connection between the two sets of channels.

[0036] After the compressor starts operating, the centrifugal force generated by the rotor's rotation drives the refrigerant oil to rise continuously along the annular gap between the outer wall of the oil suction pipe and the inner bore of the crankshaft. As the oil flows through the crankshaft oil outlet, it is guided by the inclined angle of the channel to form a rotating jet, entering the rotor's oil inlet at a specific incident angle. Inside the rotor, the oil forms a spiral trajectory under the constraint of the spiral grooves. As the pitch gradually decreases, the centrifugal force on the oil increases non-linearly, eventually forming a fan-shaped oil mist band on the outer edge of the upper end face of the rotor. The coverage angle of this oil mist band perfectly matches the radial distribution of the stator coil. Under 600W power conditions, the oil film is renewed three times per second, forming a dynamic heat exchange interface.

[0037] In practical applications, it was found that after the compressor ran continuously for four hours, the surface temperature of the stator winding rose from the initial ambient temperature to a stable value. The winding temperature using this structure remained consistently within the 120-125℃ range, resulting in a significant temperature difference compared to the 140℃ operating condition without this structure. This temperature drop effect stems from two aspects: firstly, the oil film directly contacts the winding surface, achieving conductive heat transfer, with a thermal conductivity 25 times that of air; secondly, the continuously flowing oil carries accumulated heat away from the heat source, forming a convective heat dissipation channel. On the production line, by adjusting the matching relationship between the number of oil outlets and the pitch of the spiral grooves, this structure can be adapted to motors of different power ratings. For example, for an 800W model, increasing the number of oil outlets to eight and adjusting the extension length of the spiral grooves accordingly can maintain the same level of temperature control. Furthermore, this structure demonstrates excellent adaptability to applications in different installation environments. In tilted refrigeration equipment, by adjusting the extension depth of the oil suction pipe and the outlet angle of the spiral groove, the oil film coverage area can be shifted 15° towards the direction of gravity, thereby compensating for the oil distribution deviation caused by the equipment tilt. In applications in high-temperature workshop environments, additional auxiliary heat dissipation fins are added to the rotor core to form a composite heat dissipation channel with the oil circuit system, which, in actual measurements, can further reduce the winding temperature by 5-8°C. This embodiment utilizes the kinetic energy of the rotating components themselves to drive the cooling medium, achieving directional and controllable heat management.

[0038] Example 2

[0039] In this embodiment, the crankshaft oil outlet holes adopt an asymmetrical circumferential distribution pattern. Four oil outlet holes are densely arranged within a 120° range of the upper half of the crankshaft circumference, while two supplementary channels are set in the 240° region of the lower half. This layout is designed for the special operating condition of a compressor installed at a 30° tilt, compensating for the influence of gravity by adjusting the vector direction of oil delivery. The axis of the oil outlet holes forms a dynamically changing tilt angle with the radial plane of the crankshaft. The channels in the upper half of the circumference adopt a 55° forward tilt angle, while the lower half is adjusted to 35°, ensuring that the oil jet direction is orthogonal to the tilt axis of the compressor. Correspondingly, the rotor oil inlet holes are configured with two sets of asymmetrical through holes. The diameter of the main channel is enlarged to 1.5 times that of the secondary channel, and the inlet end forms an elliptical flared structure, with its major axis aligned with the tilt direction of the crankshaft oil outlet holes.

[0040] The spiral groove cross-section was changed to a trapezoidal structure with a wider bottom and a narrower top. The bottom width remained the same as in Example 1, while the groove opening width was narrowed to two-thirds, and the sidewall inclination angle was 60°. This structure, while maintaining the oil flow capacity, enhances the structural rigidity of the groove, increasing the measured centrifugal load it can withstand by 40%. The groove extension path was adjusted to an offset structure, with the starting end offset 15° towards the compressor's tilt direction, and the end opening forming a fan-shaped diffuser, the expansion angle of which matches the projection area of ​​the stator coil in the tilted state. An axial wavy oil guide pattern was added to the interference fit surface, with the wave crest spacing consistent with the distribution period of the oil outlet holes, forming a directional guiding effect.

[0041] When the compressor operates at an angle, the oil jet generated by the asymmetrical oil outlet creates a pressure gradient at the rotor inlet, driving most of the oil along the main channel into the offset spiral groove. The trapezoidal cross-section groove generates a lateral force during the centrifugal motion of the oil, compensating for the oil film distribution offset caused by gravity. The geometric features of the fan-shaped diffuser ensure that the oil forms a spray trajectory perpendicular to the inclined installation axis when it leaves the rotor, ensuring that the effective coverage area of ​​the stator coil surface remains above 85%. The wavy oil guide pattern generates periodic pressure pulsations when the rotor rotates, promoting the penetration and diffusion of oil at the interference fit surface. Actual measurements show a 30% improvement in oil film lubrication stability under inclined operating conditions.

[0042] This embodiment discloses a spatially adaptive oil circuit guidance system that actively compensates for hydrodynamic disturbances caused by changes in installation posture through asymmetric structural features. In production practice, by adjusting the matching relationship between the oil outlet distribution angle and the spiral groove offset, the device can adapt to any installation tilt angle within the range of 15°-45°. In the application of mobile compressors in cold chain logistics vehicles, this adaptive characteristic reduces the winding temperature fluctuation range from ±8°C to ±3°C, significantly improving the system's reliability under complex operating conditions.

Claims

1. A compressor motor stator and rotor cooling structure, comprising a rotor (1) that is interference-fitted with a crankshaft (2) and an oil suction pipe (3) inserted into the inner bore of the crankshaft and in contact with refrigerant oil, characterized in that: The crankshaft (2) has a crankshaft oil outlet hole (4) that penetrates its inner wall in the radial direction. The rotor (1) has a rotor oil inlet hole (5) at the bottom that communicates with the crankshaft oil outlet hole (4). The rotor (1) has a spiral groove (6) extending axially inside. The first end of the spiral groove (6) communicates with the rotor oil inlet hole (5), and the second end extends to the outer edge of the upper end face of the rotor (1).

2. The compressor motor stator and rotor cooling structure according to claim 1, characterized in that: The number of crankshaft oil outlet holes (4) is one, two or more; the crankshaft oil outlet holes (4) are multiple independent channels evenly distributed along the circumference of the crankshaft, and the axis of each channel is inclined relative to the crankshaft axis, and the inclination direction is the same as the rotor rotation direction.

3. The compressor motor stator and rotor cooling structure according to claim 2, characterized in that: The crankshaft oil outlet (4) has a guide lip structure extending in the direction of rotor rotation at its outlet end.

4. The compressor motor stator and rotor cooling structure according to claim 1, characterized in that: The rotor oil inlet (5) includes at least one pair of through holes symmetrically arranged along the rotor axis; the connection between the through holes and the spiral groove (6) forms a flared structure.

5. The compressor motor stator and rotor cooling structure according to claim 1, characterized in that: The pitch of the spiral groove (6) gradually decreases along the direction of oil flow, and the bottom of the groove is provided with a continuous convex ridge structure (61) extending along the spiral direction.

6. The compressor motor stator and rotor cooling structure according to claim 5, characterized in that: The cross-section of the convex ridge structure (61) is triangular, with its apex pointing towards the center line of the spiral groove.

7. The compressor motor stator and rotor cooling structure according to any one of claims 1-6, characterized in that: The annular gap (3a) between the outer wall of the oil suction pipe (3) and the inner hole of the crankshaft is provided with a spiral guide pattern, and the spiral direction of the guide pattern is opposite to the rotation direction of the rotor.

8. The compressor motor stator and rotor cooling structure according to any one of claims 1-6, characterized in that: The rotor (1) and crankshaft (2) have an annular oil guide groove (7) on their interference fit surfaces. The annular oil guide groove (7) is connected to the crankshaft oil outlet (4) through a radial connecting hole.

9. The compressor motor stator and rotor cooling structure according to claim 5, characterized in that: The number of the spiral grooves (6) is one, two or more, and each spiral groove (6) is uniformly arranged around the inside of the rotor.

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