A method for designing mechanical performance of a motor rotor based on stirling refrigerator

Abstract

The application discloses a kind of based on stirling cryogenic machine motor rotor mechanical performance design method, it is related to stirling cryogenic machine technical field, design method includes: S1, first obtain the operating frequency of stirling cryogenic machine;S2, establish rotor system axial dynamics model;S3, define as single degree of freedom mass stiffness system in axial movement of rotor system, and calculate current single degree of freedom mass stiffness system inherent frequency;S4, carry out counterweight mass design and / or waveform spring axial stiffness adjustment;S5, verify whether new single degree of freedom mass stiffness system inherent frequency avoids excitation band;S6, then determine final counterweight mass and waveform spring stiffness design value.The influence of counterweight on rotor axial movement and the resonance problem of rotor system axial movement and cryogenic machine operating frequency are comprehensively considered, and the abnormal vibration and noise caused by these factors can be effectively avoided by the design method, and the operating stability of the cryogenic machine is significantly improved.

Description

Technical Field

[0001] This invention relates to the field of Stirling refrigerator technology, and in particular to a design method for the mechanical performance of a Stirling refrigerator motor rotor. Background Technology

[0002] Stirling refrigerators, as important refrigeration equipment, are widely used in many fields, such as aerospace and electronic equipment cooling. The mechanical properties of their motor rotor play a crucial role in the overall performance and stability of the refrigerator.

[0003] Current Stirling refrigerator motor rotor designs do not adequately consider the impact of counterweights on rotor axial motion. While counterweights are used to balance unbalanced forces generated during rotor rotation, their effect on axial motion is often overlooked. Furthermore, insufficient attention is paid to whether the rotor's axial motion resonates with the refrigerator's operating frequency. Resonance, once it occurs, can cause severe vibration and noise, not only reducing refrigerator performance but also potentially damaging components and shortening its lifespan. Therefore, existing Stirling refrigerator motor rotor designs are flawed and cannot effectively avoid problems caused by improper counterweight placement and resonance between axial motion and operating frequency. Summary of the Invention

[0004] The purpose of this invention is to provide a design method for the mechanical performance of a Stirling refrigerator motor rotor to solve the above-mentioned technical problems.

[0005] The technical solution adopted in this invention is as follows: A design method for the mechanical performance of a Stirling refrigerator motor rotor includes a rotor system disposed inside the Stirling refrigerator, one end of which is connected to a wave spring, and a counterweight is disposed on the rotor system; the design method includes: S1. First, obtain the operating frequency of the Stirling refrigerator; S2. Establish the axial dynamics model of the rotor system; S3. Define the rotor system as a single-degree-of-freedom mass stiffness system in axial motion, and calculate the natural frequency of the current single-degree-of-freedom mass stiffness system. S4. Design the mass of the counterweight and / or adjust the axial stiffness of the wave spring; S5. Verify whether the natural frequency of the new single-degree-of-freedom mass stiffness system avoids the excitation frequency band. S6. Then determine the final design values ​​for the counterweight mass and the wave spring stiffness.

[0006] Preferably, in step A1, when obtaining the operating frequency of the Stirling refrigerator, the rated speed range, excitation frequency, and rotational speed multiple of the Stirling refrigerator need to be considered.

[0007] Preferably, in step S2, when establishing the axial dynamic model of the rotor system, the axial stiffness of the wave spring and the equivalent rotor mass of the rotor system need to be considered.

[0008] Preferably, the formula for calculating the natural frequency of the single-degree-of-freedom mass stiffness system is:

[0009] Where k is the axial stiffness of the wave spring; m is the total mass that moves axially with the rotor.

[0010] 5. The design method for the mechanical performance of the rotor of the Stirling refrigerator motor as described in claim 1, characterized in that, after calculating the natural frequency of the current single-degree-of-freedom mass stiffness system, it is necessary to determine whether there is a risk of resonance. If so, step S4 is executed; if not, step S6 is executed.

[0011] Preferably, step S4 further includes step S4.1, increasing / decreasing the mass of the counterweight while ensuring the design requirements of the unbalanced force inside the counterweight are met.

[0012] Preferably, step S4 further includes step S4.2, adjusting the axial stiffness of the wave spring when the balance force requirement of the counterweight cannot be met.

[0013] Preferably, step S4 further includes step S4.3, which involves adjusting the mass of the counterweight and the axial stiffness of the wave spring.

[0014] As a preferred option, step S7 is also included: installation test verification to determine whether it meets the design requirements. If not, steps S1-S6 are repeated.

[0015] The above technical solution has the following advantages or beneficial effects: (1) In this invention, by comprehensively considering the influence of the counterweight on the axial movement of the rotor and the resonance between the axial movement of the rotor system and the operating frequency of the refrigeration machine, this design method can effectively avoid abnormal vibration and noise caused by these factors, thus significantly improving the operating stability of the refrigeration machine, reducing the risk of damage to the refrigeration machine components caused by vibration and noise, and extending the service life of the refrigeration machine.

[0016] (2) In this invention, by adjusting the mass of the counterweight and the axial stiffness of the wave spring through this design method, the natural frequency of the rotor system can be made to avoid the excitation frequency band, which effectively improves the stability and reliability of the rotor during axial movement.

[0017] (3) In this invention, the reliability of the design is ensured through the verification process in steps S1-S7, from theoretical calculation verification to on-site experimental verification. In the theoretical calculation stage, the theoretical rationality of the design is ensured by continuously adjusting and verifying whether the inherent frequency avoids the excitation frequency band. On-site experimental verification further verifies the feasibility and effectiveness of the design in practical applications. This dual verification mechanism greatly reduces design risk, increases the success rate of the design, and reduces the increase in R&D costs and production delays caused by unreasonable design. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the rotor system and the wave spring in this invention. Figure 2 This is a flowchart of the design method for the mechanical performance of the Stirling refrigerator motor rotor in this invention.

[0019] In the diagram: 1. Rotor system; 2. Wave spring; 3. Counterweight. Detailed Implementation

[0020] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] In the description of this invention, it should be noted that terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for 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. Therefore, they should not be construed as limitations on this invention. Furthermore, terms such as "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0022] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" 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 or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0023] Please see Figures 1 to 2 The diagram illustrates a preferred embodiment, showcasing a design method for the mechanical performance of a Stirling refrigerator motor rotor. The method includes a rotor system 1 housed within the Stirling refrigerator, one end of which is connected to a wave spring 2. A counterweight 3 is mounted on the rotor system 1. The design method comprises: S1. First, obtain the operating frequency of the Stirling refrigerator. In this embodiment, it is necessary to determine the rated speed range of the Stirling refrigerator based on its technical parameters. Simultaneously, the excitation frequency needs to be determined. The excitation frequency is usually related to the working principle and internal structure of the refrigerator and needs to be determined through analysis of the refrigerator's operation process. Additionally, the rotational speed ratio needs to be considered, as it is related to the mechanical structure and motion characteristics of the refrigerator.

[0024] S2. Establish the axial dynamic model of rotor system 1. When establishing the axial dynamic model of rotor system 1, the axial stiffness of wave spring 2 and the equivalent rotor mass of rotor system 1 must be fully considered. For the axial stiffness of wave spring 2, the material properties, geometric dimensions (such as spring wire diameter, spring outer diameter, effective number of turns, etc.), and stress conditions of wave spring 2 must be considered. For the equivalent rotor mass of rotor system 1, the mass of the rotor itself, the mass of various components installed on the rotor (such as the mass of counterweight 3), and the equivalent mass components participating in the axial motion must be considered.

[0025] S3. Define rotor system 1 as a single-degree-of-freedom mass-stiffness system in axial motion, and calculate the natural frequency of the current single-degree-of-freedom mass-stiffness system; wherein, the formula for calculating the natural frequency of the single-degree-of-freedom mass-stiffness system is: Where k is the axial stiffness of the wave spring 2; m is the total mass moving axially with the rotor. This formula can be used to accurately calculate the natural frequency of a single-degree-of-freedom mass-stiffness system.

[0026] S4. Perform mass design of counterweight 3 and / or adjustment of axial stiffness of wave spring 2; after calculating the natural frequency of the current single-degree-of-freedom mass stiffness system, it is necessary to determine whether there is a risk of resonance. If yes, proceed to step S4; otherwise, proceed to step S6.

[0027] S5. Verify whether the natural frequency of the new single-degree-of-freedom mass stiffness system avoids the excitation frequency band; where the excitation frequency band is the vibration excitation frequency band generated during the operation of the Stirling refrigerator.

[0028] S6. Then determine the final design values ​​for the mass of counterweight 3 and the stiffness of wave spring 2.

[0029] Furthermore, as a preferred implementation, step S4 further includes step S4.1: increasing / decreasing the mass of the counterweight 3, while ensuring the design requirements of the unbalanced force inside the counterweight 3 are met. The natural frequency of the single-degree-of-freedom mass stiffness system is adjusted by increasing / decreasing the mass of the counterweight 3. If the calculated natural frequency is lower than the lower limit of the excitation frequency band, the mass of the counterweight 3 can be appropriately increased, the total mass m recalculated, and the natural frequency recalculated.

[0030] Furthermore, as a preferred embodiment, step S4 further includes step S4.2: adjusting the axial stiffness of the wave spring 2 when the balance force requirement of the counterweight 3 cannot be met. In this embodiment, if adjusting the mass of the counterweight 3 alone cannot meet the balance force requirement of the counterweight 3 or still cannot effectively avoid the excitation frequency band, step S4.2 can be executed. Here, when adjusting the axial stiffness of the wave spring 2, the axial stiffness of the wave spring 2 can be changed by changing the material, geometric dimensions, etc.

[0031] Furthermore, as a preferred implementation, step S4 further includes step S4.3, simultaneously adjusting the mass of the counterweight 3 and the axial stiffness of the wave spring 2. In some cases, it may be necessary to simultaneously adjust the mass of the counterweight 3 and the axial stiffness of the wave spring 2 to achieve the best design effect. After each adjustment, step S5 must be executed again to verify whether the natural frequency of the new single-degree-of-freedom mass-stiffness system avoids the excitation frequency band.

[0032] Furthermore, as a preferred implementation, step S7 is also included: installation and experimental verification to determine whether the design requirements are met. If not, steps S1-S6 are repeated. The rotor system 1 manufactured based on the above design values ​​is installed in the Stirling refrigerator for experimental verification. During the experiment, the operating status of the refrigerator is monitored, including vibration, noise level, and refrigeration performance. If the experimental results show that the refrigerator operates smoothly, vibration and noise are within the allowable range, and the refrigeration performance meets the design requirements, then the design is considered successful. If the experimental results do not meet the design requirements, such as excessive vibration, excessive noise, or poor refrigeration performance, steps S1-S6 need to be repeated to re-analyze and adjust the refrigerator operating frequency, the dynamic model of rotor system 1, the mass of counterweight 3, and the stiffness of wave spring 2 until the design requirements are met.

[0033] The above description is merely a preferred embodiment of the present invention and does not limit the implementation and protection scope of the present invention. Those skilled in the art should realize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for designing the mechanical performance of a Stirling refrigerator motor rotor, comprising a rotor system disposed inside a Stirling refrigerator, one end of the rotor system being connected to a wave spring, and a counterweight being disposed on the rotor system; characterized in that, The design method includes: S1. First, obtain the operating frequency of the Stirling refrigerator; S2. Establish the axial dynamics model of the rotor system; S3. Define the rotor system as a single-degree-of-freedom mass stiffness system in axial motion, and calculate the natural frequency of the current single-degree-of-freedom mass stiffness system. S4. Design the mass of the counterweight and / or adjust the axial stiffness of the wave spring; S5. Verify whether the natural frequency of the new single-degree-of-freedom mass stiffness system avoids the excitation frequency band. S6. Then determine the final design values ​​for the counterweight mass and the wave spring stiffness.

2. The design method for the mechanical performance of a Stirling refrigerator motor rotor as described in claim 1, characterized in that, In step A1, when obtaining the operating frequency of the Stirling refrigerator, it is necessary to consider the rated speed range, excitation frequency, and frequency multiple of the Stirling refrigerator.

3. The design method for the mechanical performance of a Stirling refrigerator motor rotor as described in claim 1, characterized in that, In step S2, when establishing the axial dynamic model of the rotor system, the axial stiffness of the wave spring and the equivalent rotor mass of the rotor system need to be considered.

4. The design method for the mechanical performance of a Stirling refrigerator motor rotor as described in claim 1, characterized in that, The formula for calculating the natural frequency of the single-degree-of-freedom mass stiffness system is as follows: ； Where k is the axial stiffness of the wave spring; m is the total mass that moves axially with the rotor.

5. The design method for the mechanical performance of a Stirling refrigerator motor rotor as described in claim 1, characterized in that, After calculating the natural frequency of the current single-degree-of-freedom mass stiffness system, it is necessary to determine whether there is a risk of resonance. If yes, proceed to step S4; otherwise, proceed to step S6.

6. The design method for the mechanical performance of a Stirling refrigerator motor rotor as described in claim 1, characterized in that, Step S4 further includes step S4.1, increasing / decreasing the mass of the counterweight while ensuring the design requirements of the unbalanced force inside the counterweight are met.

7. The design method for the mechanical performance of a Stirling refrigerator motor rotor as described in claim 1, characterized in that, Step S4 further includes step S4.2: when the balance force requirement of the counterweight cannot be met, adjust the axial stiffness of the wave spring.

8. The design method for the mechanical performance of a Stirling refrigerator motor rotor as described in claim 1, characterized in that, Step S4 further includes step S4.3, which involves adjusting the mass of the counterweight and the axial stiffness of the wave spring.

9. The design method for the mechanical performance of a Stirling refrigerator motor rotor as described in claim 1, characterized in that, It also includes step S7, installation test verification, to determine whether it meets the design requirements. If not, repeat steps S1-S6.

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