CN107477021B

CN107477021B - Impeller transmission structure and centrifugal compressor

Info

Publication number: CN107477021B
Application number: CN201710874206.0A
Authority: CN
Inventors: 周义; 张治平; 钟瑞兴; 蒋楠; 蒋彩云; 陈玉辉; 刘增岳; 雷连冬; 欧阳鑫望; 陈健
Original assignee: Gree Electric Appliances Inc of Zhuhai
Current assignee: Gree Electric Appliances Inc of Zhuhai
Priority date: 2017-09-25
Filing date: 2017-09-25
Publication date: 2023-07-04
Anticipated expiration: 2037-09-25
Also published as: CN107477021A

Abstract

The invention relates to an impeller transmission structure, comprising: the rotor comprises a rotor shaft (1), an impeller and at least two half-long cylindrical keys (4), wherein the impeller is sleeved on the rotor shaft (1), and multi-key transmission is realized between the at least two half-long cylindrical keys (4) and the rotor shaft (1); the rotor shaft (1) is also provided with a thread locking structure for locking the impeller on the rotor shaft (1). According to the invention, torque is transmitted through the half-long cylindrical key, so that axial locking force can be greatly reduced, stress concentration at the root of an impeller keyway can be effectively reduced, and the effective contact area between the impeller and the impeller can be increased, so that the transmission process of the impeller during high-speed rotation is more reliable, the locking force requirement of an impeller transmission structure on a thread locking structure is reduced, an oil pressure tool for realizing large locking force is not required, the impeller assembly and disassembly efficiency of links such as production, after-sale links and the like can be greatly improved, and the comprehensive benefit is improved.

Description

Impeller transmission structure and centrifugal compressor

Technical Field

The invention relates to a rotation transmission technology, in particular to an impeller transmission structure and a centrifugal compressor.

Background

At present, in order to avoid the phenomenon of stress concentration of the centrifugal compressor impeller during torque transmission, a keyless torque transmission structure is mostly adopted. In order to ensure the friction force required by the torque, the hydraulic stretching and nut locking modes are adopted, and the impeller and the back step generate enough friction force to transmit the torque through the screw tightening force of the locking nut. Although the problem of stress concentration can be solved to this structure, but needs special oil pressure equipment and the tensile frock of axle, and the assembly process needs to add the oil pressure step by step to the deformation of axle is recorded, prevents to overstretch, destroys main shaft intensity, and requires very high to operating personnel specialty level, brings very big inconvenience for links such as production, after-sales assembly, dismantlement, has restricted production efficiency's promotion and after-sales maintenance progress, has also caused higher manpower and materials cost.

Disclosure of Invention

The invention aims to provide an impeller transmission structure and a centrifugal compressor, which can ensure the operation reliability of an impeller during high-speed operation and improve the assembly and disassembly efficiency of the impeller.

In order to achieve the above object, the present invention provides an impeller driving structure comprising: the impeller is sleeved on the rotor shaft, and multi-key transmission is realized through the at least two half-long cylindrical keys and the rotor shaft; the rotor shaft is also provided with a thread locking structure for locking the impeller on the rotor shaft.

Further, the half-long cylindrical key comprises a half-long cylindrical part and a straight quadrangular prism part which are integrally manufactured, and the half-long cylindrical part and the straight quadrangular prism part are in smooth transition.

Further, a half-long cylindrical key groove is formed in the impeller, a flat key groove is formed in the rotor shaft at a position corresponding to the half-long cylindrical key groove, the half-long cylindrical portion and a part of the straight quadrangular portion are arranged in the half-long cylindrical key groove, and the other part of the straight quadrangular portion is arranged in the flat key groove.

Further, the at least two semi-long cylindrical keys are arranged at regular intervals in the circumferential direction of the rotor shaft.

Further, the effective height H of the semi-long cylindrical key in contact with the semi-long cylindrical key groove is 0.6-0.75 times of the effective height H of the semi-long cylindrical key.

Further, the half-long cylindrical key is in transition fit with the half-long cylindrical key groove, and a radial clearance delta h between the half-long cylindrical key and the half-long cylindrical key groove is 0.3-0.5 mm.

Further, the aspect ratio B/H of the half-length cylindrical key is 0.5-2.

Further, the number of the half-long cylindrical keys arranged between each impeller and the rotor shaft is 2-3.

Further, the rotor shaft is in interference fit with the impeller.

Further, the thread locking structure comprises a lock nut, a locking thread piece and a thread structure arranged at the end part of the rotor shaft, and the locking thread piece and the lock nut are sequentially screwed on the thread structure at the end part of the rotor shaft.

Further, the thread structure includes a first thread portion and a second thread portion respectively engaged with the lock nut and the lock screw, the first thread portion and the second thread portion being opposite in rotation direction.

Further, the first screw portion is an external screw thread provided on an outer periphery of the rotor shaft end portion, and the second screw portion is an internal screw thread provided to extend from an end plane of the rotor shaft to a mounting position of the impeller.

Further, the rotor shaft end portion includes a second end section and a first end section extending along an end plane of the rotor shaft toward a mounting position of the impeller, the first threaded portion is an external thread provided at an outer periphery of the first end section, and the second threaded portion is an external thread provided at an outer periphery of the second end section.

Further, the nominal diameter M1 of the first threaded portion is 2 to 3 times the nominal diameter M2 of the second threaded portion.

Further, the thread length L1 of the first thread portion is not less than 10 times the thread pitch P1, and/or the thread length L2 of the second thread portion is not less than 5 times the thread pitch P2.

Further, the outer contour of the locking screw is umbrella-shaped, and the locking nut and the outer contour of the locking screw are streamline and smoothly transited.

Further, an assembly groove for tool assembly is formed in the periphery of the lock nut.

Further, the number of the assembly grooves is 4-8, and the assembly grooves are uniformly distributed on the periphery of the locking nut.

Further, the cross-sectional diameter of the assembly groove is 10-15 mm.

Further, the impeller comprises at least two stages of impeller discs which are respectively sleeved at different axial positions of the rotor shaft and are separated by a supporting sleeve and/or a rotor shaft step.

Further, the supporting sleeve is in interference fit with the rotor shaft, and the interference is 0.03-0.2 mm.

In order to achieve the above object, the present invention provides a centrifugal compressor, comprising the impeller driving structure.

Based on the technical scheme, the invention adopts a plurality of half-long cylindrical keys to realize the transmission between the rotor shaft and the impeller, and realizes the locking of the impeller on the rotor shaft through a thread locking structure. Through half long cylinder key transmission moment of torsion, can reduce axial locking force by a wide margin, reduce the stress concentration of impeller keyway root effectively to can increase the effective area of contact with the impeller, consequently make the impeller more reliable at the transmission process when high-speed rotation, make impeller transmission structure to screw locking structure's locking force requirement reduce simultaneously, need not to use the oil pressure frock that realizes big locking force, consequently can greatly improve the impeller of links such as production and after-sales and install and remove efficiency, improve the comprehensive benefits.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiments of the invention and together with the description serve to explain the invention and do not constitute a limitation on the invention. In the drawings:

fig. 1 is a schematic structural view of an embodiment of the impeller driving structure of the present invention.

Fig. 2 is a schematic view of the AA section of fig. 1.

Fig. 3 is a schematic view of the mating structure of the half-length cylindrical key and the key groove in fig. 2.

Fig. 4 is an enlarged schematic view of the thread locking mechanism of the embodiment of fig. 1.

Fig. 5 is a schematic structural view of a lock nut in an embodiment of the impeller driving structure of the present invention.

Fig. 6 is a schematic structural view of another embodiment of the impeller driving structure of the present invention.

Detailed Description

The technical scheme of the invention is further described in detail through the drawings and the embodiments.

Fig. 1 is a schematic structural view of an embodiment of the impeller driving structure of the present invention. With reference to fig. 2 to 5, the impeller driving structure of the present embodiment includes: a rotor shaft 1, an impeller and at least two semi-long cylindrical keys 4. The impeller is sleeved on the rotor shaft 1, and multi-key transmission is realized with the rotor shaft 1 through at least two half-long cylindrical keys 4. The assembly of the impeller with the rotor shaft 1 preferably employs an interference fit of the rotor shaft 1 with the impeller to ensure concentricity between the two meets high requirements. The rotor shaft 1 is also provided with a thread locking structure for locking the impeller on the rotor shaft 1. The thread locking structure is matched with the key transmission of the plurality of half-long cylindrical keys 4, so that the use of an oil pressure tool can be omitted, the impeller assembly and disassembly efficiency of links such as production, after-sales and the like can be greatly improved, and the economic benefit can be improved.

Referring to fig. 3, the half-length cylindrical key 4 may integrally include a half-length cylindrical portion and a straight quadrangular portion that are integrally formed, and smoothly transition between the half-length cylindrical portion and the straight quadrangular portion. In fig. 3, it can be seen that the semi-long cylindrical key 4 is in the overall shape of an upper circle and a lower circle in cross section, and the upper part of the key is in a circular arc shape, and matched with the key groove 21 in the semi-long cylindrical shape provided on the impeller 2. The half long cylindrical part and a part of the straight quadrangular prism part of the half long cylindrical key 4 are arranged in the half long cylindrical key groove, and the root part of the half long cylindrical key groove 21 is also in an arc shape, so that the stress concentration phenomenon can be reduced by matching the root part with the arc shape of the upper part of the half long cylindrical key 4. The side edge of the half-long cylindrical key groove 21 on the impeller 2 and the side edge of the half-long cylindrical key 4 can form a larger effective contact area, so that the stress of the pressed surface on the half-long cylindrical key groove 21 is reduced. A flat key groove 14 may be provided on the rotor shaft 1 at a position corresponding to the half-long cylindrical key groove 21, and another part of the straight quadrangular prism portion of the half-long cylindrical key 4 is provided in the flat key groove 14.

By transmitting torque by means of multiple keys, the axial locking force can be greatly reduced, while in order to prevent the occurrence of centroid displacement of the true shaft system, it is preferable to arrange at least two semi-long cylindrical keys 4 at regular intervals in the circumferential direction of the rotor shaft 1. For the impeller, in order to reduce the weight, a material which is relatively soft and easy to deform, such as an aluminum alloy material, needs to be selected, and a larger effective contact area is formed between the side edge of the half-long cylindrical key groove 21 and the side edge of the half-long cylindrical key 4 on the impeller 2, so as to reduce the stress of the pressed surface on the half-long cylindrical key groove 21 and reduce the degree of pressed deformation. For this purpose, referring to fig. 3, it is preferable that the effective height H of the semi-long cylindrical key 4 in contact with the semi-long cylindrical key groove 21 (i.e., the height at which the semi-long cylindrical key 4 is in contact with the semi-long cylindrical key groove 21) is 0.6 to 0.75 times the effective height H of the semi-long cylindrical key 4 (i.e., the height of the straight quadrangular portion of the semi-long cylindrical key 4), and that a proper effective height H is selected so that not only reliable transmission of torque can be achieved but also the degree of deformation of the impeller key groove can be reduced. On the other hand, the semi-long cylindrical key 4 may be fit with the semi-long cylindrical key groove 21 in transition, and the radial clearance Δh of the semi-long cylindrical key 4 with the semi-long cylindrical key groove 21 is preferably 0.3 to 0.5mm so as to ensure the key groove fit in place.

In order to be able to subject the half-length cylindrical key 4 to a sufficient shearing stress, it is preferable to make the ratio of the width B of the half-length cylindrical key 4 to the effective height H (aspect ratio B/H) 0.5 to 2. The specific aspect ratio may be selected depending on the application for which the impeller drive mechanism is to be used. In addition, since the half-length cylindrical keys 4 are larger in size and transmission performance than other shapes, there is no need to be excessive in number, and it is preferable that the number of half-length cylindrical keys 4 provided between each impeller and the rotor shaft 1 is 2 to 3. The length of the half-length cylindrical key 4 can then be determined according to the structural dimensions of the rotor shaft.

In the prior art, it is mentioned that the existing keyless torque transmission structure relies on friction force between the impeller and the step on the rotor shaft to transmit torque, so that the lock nut needs to provide larger axial force and needs to be tightened by oil pressure, but in the embodiment of the invention, the mode that a plurality of semi-long cylindrical keys 4 transmit torque by extruding the lateral extruding surface of the impeller key slot is adopted, the requirement on locking force of the thread locking structure is relatively low, and generally only the thread locking structure is required to be not loosened, so that the hydraulic tightening is not needed, and the assembly process is simpler and more convenient. In this case, the locking coefficient can be controlled to be 1 to 2. According to different application scenes of the impeller transmission structure, the thread locking structure can further realize the requirements of counteracting the pneumatic axial force and the torque transmission of the sharing part when the impeller rotates at high speed according to the needs, the locking coefficient can be controlled between 2 and 6 under the condition, and the locking coefficient can be correspondingly increased along with the increase of the torque. Specifically, referring to fig. 1, the aerodynamic axial force is denoted as F, the locking coefficient is denoted as α, and if the axial locking force is denoted as F, f=f×α. For larger locking coefficients, a tightening process and the like capable of obtaining larger locking force can be used as required.

Referring to fig. 1 and 4, the screw locking structure includes a lock nut 5, a locking screw 6, and a screw structure provided at an end of the rotor shaft 1, the locking screw 6 and the lock nut 5 being sequentially screwed on the screw structure of the end of the rotor shaft 1. The lock nut 5 realizes the locking effect on the impeller in the axial direction by abutting against the axial side wall of the impeller, and the locking screw piece can limit the loosening direction of the lock nut 5, so that the lock nut 5 is prevented from falling off in work to cause serious accidents. In order to obtain a good anti-loosening effect, it is preferable that the screw structure includes a first screw portion 12 and a

second screw portion

13,15 which are engaged with the lock nut 5 and the anti-loosening screw 6, respectively, the first screw portion 12 and the

second screw portion

13,15 being rotated in opposite directions. The thread locking structure with the opposite screw rotation directions can realize the reverse anti-loosening effect, in other words, the rotation direction of the anti-loosening screw member 6 and the rotation direction of the locking nut 5 are opposite to each other in the same movement direction, and the loosening direction of the locking nut 5 is just the screwing direction of the anti-loosening screw member 6, so that the locking nut 5 can not be loosened even if the locking screw member 6 is limited by the large axial force from the impeller at the other side, thereby ensuring the reliability of the thread locking structure.

Referring to fig. 4, the first screw portion 12 is an external screw thread provided on the outer periphery of the end portion of the rotor shaft 1, and the second screw portion 13 is an internal screw thread provided extending from the end plane of the rotor shaft 1 toward the mounting position of the impeller. The internal thread 51 of the lock nut 5 is screwed with the first thread 12, and the lock screw 6 is provided with a male external thread segment 61 which is inserted into the end plane of the rotor shaft 1 and is screwed with the second thread 13. In this way, the second thread part 12 and the second thread part 13 have at least partial length overlapping in the axis direction of the rotor shaft, so as to reduce the length of the cantilever end of the rotor shaft 1, and the whole mass center moves to one side far away from the cantilever end of the rotor shaft 1, so that the impeller and the rotor shaft can always maintain higher balance degree under high-speed rotation, the flexure resistance of the rotor shaft is enhanced, and the reliability of long-term operation of the impeller transmission structure is ensured. Under the structure of the locking screw 6, an inner hexagonal tooling hole can be arranged at the end part of the locking screw, and the tightening operation can be performed by utilizing the tooling hole.

In another embodiment of the impeller drive shown in fig. 6, the rotor shaft 1 end comprises a second end section and a first end section extending along the end plane of the rotor shaft 1 towards the mounting position of the impeller, the first threaded portion 12 being an external thread provided at the outer periphery of the first end section, the second threaded portion 15 being an external thread provided at the outer periphery of the second end section. The internal thread 51 of the lock nut 5 is in threaded engagement with the first threaded portion 12, and the lock screw 6 is provided with an internal thread segment which is in threaded engagement with the second threaded portion 15. This embodiment is particularly suitable for the case where the rotor shaft is thin, and it is difficult to provide the second screw portion of the female screw.

In the impeller drive embodiment described above, the nominal diameter M1 of the first threaded portion 12 is preferably 2-3 times the nominal diameter M2 of the second threaded

portions

13,15 to ensure that the thread strength meets the axial locking force requirements. The nominal diameter M1 of the first threaded portion 12 is generally determined by the structural dimensions of the rotor shaft, and generally M1 is not greater than the mating diameter of the impeller and the rotor shaft. In addition, it is preferable that the thread length L1 of the first thread portion 12 is not less than 10 times the thread pitch P1 and/or the thread length L2 of the

second thread portion

13,15 is not less than 5 times the thread pitch P2 to ensure that the thread strength satisfies the requirement of the axial locking force.

In the outer contour shape of the thread locking structure, the outer contour of the locking screw 6 is preferably umbrella-shaped, and the outer contour of the locking nut 5 and the locking screw 6 are streamline and smoothly transited. Therefore, the area of the shaft end can be effectively reduced, the impact of the air flow at the shaft end is relieved, the stable transition of the axial air flow is ensured, and the flow performance of the air flow is improved. The locking and anti-loosening structure matched with the internal and external reverse threads of the anti-loosening threaded piece 6 and the locking nut 5 can ensure that the rotor shaft has better flexure resistance and improves the flow performance of axial airflow.

Referring to fig. 5, in order to facilitate tightening of the lock nut 5, an assembly groove 52 for tooling assembly is preferably provided on the outer circumference of the lock nut 5. The number of the fitting grooves 52 is preferably 4 to 8 and is uniformly distributed on the outer circumference of the lock nut 5. The number of which can be set according to the requirements of the axial locking force F, in general the greater F, the greater the number of corresponding fitting grooves 52 can be set. While the cross-sectional diameter of the fitting groove 52 is preferably 10-15 mm to facilitate the fitting of the lock nut 52 in place.

In the impeller drive embodiment described above, only a single impeller may be provided on the rotor shaft 1. In the embodiment of fig. 1 and 6, the impeller may comprise two stages of

impeller discs

2 and 3, while in other embodiments the impeller may comprise more than two stages of impeller discs. The impeller discs of each stage can be keyed by at least two half-length cylindrical keys 4. For at least two stages of impeller discs, each stage of impeller discs may be arranged in a respective axial position of the rotor shaft 1 and separated by a support sleeve 7 and/or a rotor shaft step 11. The support sleeve 7 is preferably in an interference fit with the rotor shaft 1, the interference being 0.03-0.2 mm, to ensure sufficient adhesion between the support sleeve and the rotor shaft 1 for torque transmission. The diameter of the connection position of the supporting sleeve 7 and the impeller discs of different stages can be consistent with the connection diameter of the corresponding impeller discs so as to enable the pneumatic flow passage to be smoother.

The impeller transmission structure is suitable for various devices or systems which need to realize transmission between a rotor shaft and an impeller. The invention also provides a centrifugal compressor comprising the impeller transmission structure embodiment. The impeller transmission mechanism in the centrifugal compressor needs to run at a high speed and has flowing air flow in the axial direction, but the impeller transmission structure embodiment of the invention can ensure the reliability of transmission under high-speed rotation and ensure smooth air flow, and on the other hand, the integral assembly and disassembly efficiency of the centrifugal compressor is improved by simplifying the assembly and disassembly process of the impeller, thereby improving the comprehensive benefit.

Finally, it should be noted that the above-mentioned embodiments are only for illustrating the technical scheme of the present invention and are not limiting; while the invention has been described in detail with reference to the preferred embodiments, those skilled in the art will appreciate that: modifications may be made to the specific embodiments of the present invention or equivalents may be substituted for part of the technical features thereof; without departing from the spirit of the invention, it is intended to cover the scope of the invention as claimed.

Claims

1. An impeller drive structure, comprising: the rotor comprises a rotor shaft (1), an impeller and at least two half-long cylindrical keys (4), wherein the impeller is sleeved on the rotor shaft (1), and multi-key transmission is realized between the at least two half-long cylindrical keys (4) and the rotor shaft (1); the rotor shaft (1) is also provided with a thread locking structure for locking the impeller on the rotor shaft (1);

the half-long cylindrical key (4) comprises a half-long cylindrical part and a straight quadrangular prism part which are integrally manufactured, and the half-long cylindrical part and the straight quadrangular prism part are in smooth transition.

2. The impeller transmission structure according to claim 1, characterized in that a half-long cylindrical key groove (21) is provided on the impeller, a flat key groove (14) is provided on the rotor shaft (1) at a position corresponding to the half-long cylindrical key groove (21), the half-long cylindrical portion and a part of the straight quadrangular portion are provided in the half-long cylindrical key groove, and the other part of the straight quadrangular portion is provided in the flat key groove (14).

3. Impeller transmission according to claim 1, characterized in that the at least two semi-long cylindrical keys (4) are arranged at regular intervals in the circumferential direction of the rotor shaft (1).

4. Impeller transmission structure according to claim 2, characterized in that the effective height H of the semi-long cylindrical key (4) in contact with the semi-long cylindrical key slot (21) is 0.6-0.75 times the effective height H of the semi-long cylindrical key (4).

5. Impeller transmission structure according to claim 2, characterized in that the half-length cylindrical key (4) is in transition fit with the half-length cylindrical key groove (21), and the radial clearance Δh of the half-length cylindrical key (4) and the half-length cylindrical key groove (21) is 0.3-0.5 mm.

6. Impeller drive according to claim 2, characterized in that the aspect ratio B/H of the half-length cylindrical key (4) is 0.5-2.

7. Impeller transmission according to claim 1, characterized in that the number of half-length cylindrical keys (4) provided between each impeller and the rotor shaft (1) is 2-3.

8. Impeller transmission structure according to claim 1, characterized in that the rotor shaft (1) is in an interference fit with the impeller.

9. The impeller transmission structure according to claim 1, characterized in that the thread locking structure comprises a lock nut (5), a locking screw (6) and a thread structure provided at the end of the rotor shaft (1), the locking screw (6) and the lock nut (5) being screwed onto the thread structure of the end of the rotor shaft (1) in sequence.

10. Impeller transmission according to claim 9, characterized in that the screw structure comprises a first screw thread portion (12) and a second screw thread portion (13, 15) cooperating with the lock nut (5) and the anti-loose screw thread (6), respectively, the first screw thread portion (12) being in a counter-rotation with the second screw thread portion (13, 15).

11. The impeller transmission structure according to claim 10, characterized in that the first screw thread portion (12) is an external screw thread provided at an outer periphery of an end portion of the rotor shaft (1), and the second screw thread portion (13) is an internal screw thread provided extending from an end plane of the rotor shaft (1) to a mounting position of the impeller.

12. The impeller drive according to claim 10, characterized in that the end of the rotor shaft (1) comprises a second end section and a first end section extending along an end plane of the rotor shaft (1) towards the mounting position of the impeller, the first threaded portion (12) being an external thread provided at the outer periphery of the first end section, the second threaded portion (15) being an external thread provided at the outer periphery of the second end section.

13. Impeller transmission according to claim 10, characterized in that the nominal diameter M1 of the first threaded portion (12) is 2-3 times the nominal diameter M2 of the second threaded portion (13, 15).

14. Impeller transmission according to claim 10, characterized in that the thread length L1 of the first thread part (12) is not smaller than 10 times the thread pitch P1 and/or the thread length L2 of the second thread part (13, 15) is not smaller than 5 times the thread pitch P2.

15. Impeller transmission structure according to claim 9, characterized in that the outer contour of the locknut (6) is umbrella-shaped and the locknut (5) is streamlined and smoothly transiting with the outer contour of the locknut (6).

16. Impeller transmission structure according to claim 9, characterized in that an assembly groove (52) for tooling assembly is provided on the outer circumference of the lock nut (5).

17. Impeller transmission structure according to claim 16, characterized in that the number of the assembly grooves (52) is 4-8, uniformly distributed on the periphery of the lock nut (5).

18. Impeller transmission structure according to claim 16, characterized in that the cross-sectional diameter of the fitting groove (52) is 10-15 mm.

19. Impeller transmission according to claim 1, characterized in that the impeller comprises at least two stages of impeller discs, which are respectively sleeved at different axial positions of the rotor shaft (1) and are separated by a support sleeve (7) and/or a rotor shaft step (11).

20. Impeller transmission structure according to claim 19, characterized in that the supporting sleeve (7) is in interference fit with the rotor shaft (1) with an interference of 0.03-0.2 mm.

21. A centrifugal compressor comprising an impeller drive according to any one of claims 1 to 20.