A method for calculating the crankshaft strength of a range extender

Abstract

This invention discloses a method for calculating the crankshaft strength of a range extender, belonging to the field of crankshaft technology, and solves the problem of inaccurate results in existing reliability assessments of range extender crankshafts. The calculation method includes building a basic motor calculation model in AVL dynamics calculation software, performing electromagnetic calculations for all motor operating conditions, acquiring load data, and generating load map files, current map files, and motor control parameters. A crankshaft dynamics calculation model is then built in AVL EXCITE, and the data generated during the motor calculation process is loaded into the crankshaft dynamics calculation model to perform crankshaft dynamics calculations, calculating the dynamic characteristics under the range extender's operating conditions. The dynamics calculation data is then imported into fatigue calculation software for calculations to obtain the fatigue safety factor and evaluate crankshaft reliability. This method for calculating the crankshaft strength of a range extender ensures the accuracy of reliability assessments.

Description

Technical Field

[0001] This invention relates to the field of crankshaft technology, and in particular to a method for calculating the strength of a range extender crankshaft. Background Technology

[0002] The crankshaft is a crucial component of an engine, and its reliability significantly impacts the overall engine reliability. Currently, the reliability assessment of crankshafts in traditional engines is relatively mature, and the failure rate related to crankshaft design is very low.

[0003] With the country's vigorous development of new energy, new energy power is booming. In the field of power machinery, hybrid power has become an indispensable technical solution. Among them, the range extender is a hybrid power solution that has been developed relatively early, has relatively low technical complexity, and is relatively mature in application. This solution drives a generator at the engine flywheel end to charge the power battery, thereby driving the vehicle to work. Therefore, the reliability assessment of the crankshaft of the range extender has become an essential task.

[0004] Unlike traditional engine crankshaft reliability assessments, the assessment of range extender crankshafts has the following shortcomings:

[0005] (1) When the range extender is working, the vibration will cause the stator and rotor centers of the motor to deviate, resulting in an eccentric magnetic pull on the stator, which will test the reliability of the crankshaft. The current calculation method cannot yet take into account the influence of this load.

[0006] (2) When the range extender is working, the trajectory of the rotor eccentricity is not clear. That is, the angle and distance of the rotor eccentricity are different under different crankshaft rotation angles, and the magnitude and direction of the eccentric magnetic pull are constantly changing. Therefore, different magnitudes and directions of motor loads must be applied in real time according to the actual working conditions of the rotor. In other words, it is not possible to load this part of the load in real time.

[0007] Due to the influence of the eccentric magnetic pull of the stator and rotor, the test evaluation results are biased and cannot obtain accurate evaluation data. In actual use, this may lead to malfunctions and damage to the crankshaft. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to address the above-mentioned shortcomings of the prior art by providing a method for calculating the strength of a range extender crankshaft, providing load data under different operating conditions, providing data basis for reliability assessment of the range extender crankshaft, ensuring the accuracy of reliability assessment, and having the characteristics of wide application range and strong practicality.

[0009] The technical solution adopted in this invention is: a method for calculating the crankshaft strength of a range extender, which includes the following steps:

[0010] Step S1: Collect input data for the motor model and build a basic motor calculation model in the EMT motor calculation tool of the AVL dynamics calculation software;

[0011] Step S2: By setting the motor test operating point, perform electromagnetic calculations on the motor test operating point using the basic motor calculation model, and obtain the electromagnetic load results;

[0012] Step S3: Build a basic model of the motor in commercial electromagnetic calculation software, and perform electromagnetic calculations for the same motor test conditions as in step S2, and obtain the electromagnetic load results for the test conditions.

[0013] Step S4: Compare the two load results generated by the EMT motor calculation tool and the commercial electromagnetic calculation software to check whether the calculation results of the AVL dynamics calculation software are accurate;

[0014] Step S5: Perform electromagnetic calculations for all motor operating conditions, obtain all load data under the entire motor operating conditions, and generate load map files, current map files, and motor control parameters;

[0015] Step S6: Collect the input data required for crankshaft dynamics calculation and build a crankshaft dynamics calculation model in AVL EXCITE;

[0016] Step S7: Load the motor load map and current map generated during the motor calculation process into the crankshaft dynamics calculation model. Combine the obtained motor control parameters, debug the dynamics model and carry out crankshaft dynamics calculation to calculate the dynamic characteristics of the range extender under working conditions.

[0017] Step S8: Import the data generated by the dynamic calculation into the fatigue calculation software to carry out the calculation, obtain the fatigue safety factor, and evaluate whether the crankshaft reliability meets the requirements.

[0018] As a further improvement, in step S1, the input data required for modeling includes the motor's performance parameters, stator and rotor lamination design parameters, winding design parameters, and stator and rotor lamination parameters.

[0019] Furthermore, in step S2, the motor test operating point is taken as the operating point under the rated power of the motor.

[0020] Furthermore, in step S3, the commercial electromagnetic calculation software includes Jmag and Mawell.

[0021] Furthermore, in step S4, when the calculation results of the AVL dynamics calculation software are different from those of the commercial electromagnetic calculation software, the deviation is outside the error range, and the basic calculation model of the motor needs to be re-established.

[0022] Furthermore, in step S5, by performing linear fundamental wave model calculations of the motor, data on motor control parameters, including flux linkage, DC inductance, and AC inductance, are obtained during dynamic calculation and debugging.

[0023] Furthermore, in step S5, the motor operating conditions include operating conditions with different parameters such as motor speed, load, and eccentricity.

[0024] Furthermore, in step S6, the input data required for crankshaft dynamics calculation includes engine performance parameters, whole engine model, structural parameters of crankshaft and connecting rod mechanism, engine cylinder pressure data, and fuel supply boundary values.

[0025] Furthermore, in step S7, DC and AC calculations are performed to generate electromagnetic load maps under direct-axis current and quadrature-axis current with different parameters.

[0026] Beneficial effects

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] (1) Added the motor calculation model built on the dynamic calculation software, and calibrated the motor model built on the motor module in the dynamic calculation software and the professional electromagnetic calculation software, which effectively improved the accuracy of the motor calculation model and ensured the accuracy of the calculation data.

[0029] (2) Introduce a motor calculation unit into the crankshaft strength calculation model. Generate electromagnetic load maps under different eccentric distances and parameters of direct-axis current and quadrature-axis current through the basic motor calculation model. Load the motor load, which changes constantly according to the dynamic characteristics, into the crankshaft reliability calculation model. Calculate the dynamic characteristics under the working conditions of the range extender. The influence of motor load on crankshaft reliability can be obtained. This allows for further analysis of the impact of motor load on crankshaft fatigue, so as to design the crankshaft structure in the future, thereby ensuring that the service life of the crankshaft meets the design requirements and ensuring the stable operation of the engine. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the calculation process of the present invention. Detailed Implementation

[0031] The present invention will be further described below with reference to specific embodiments shown in the accompanying drawings.

[0032] See Figure 1 This invention discloses a method for calculating the crankshaft strength of a range extender, comprising the following steps:

[0033] Step S1: Collect input data for the motor model and build a basic motor calculation model in the EMT motor calculation tool of the AVL dynamics calculation software;

[0034] Step S2: By setting the motor test operating point, perform electromagnetic calculations on the motor test operating point using the basic motor calculation model, and obtain the electromagnetic load results;

[0035] Step S3: Build a basic model of the motor in commercial electromagnetic calculation software, and perform electromagnetic calculations for the same motor test conditions as in step S2, and obtain the electromagnetic load results for the test conditions.

[0036] Step S4: Compare the two load results generated by the EMT motor calculation tool and the commercial electromagnetic calculation software to check whether the calculation results of the AVL dynamics calculation software are accurate;

[0037] Step S5: Perform electromagnetic calculations for all motor operating conditions, obtain all load data under the entire motor operating conditions, and generate load map files, current map files, and motor control parameters;

[0038] Step S6: Collect the input data required for crankshaft dynamics calculation and build a crankshaft dynamics calculation model in AVL EXCITE;

[0039] Step S7: Load the motor load map and current map generated during the motor calculation process into the crankshaft dynamics calculation model. Combine the obtained motor control parameters, debug the dynamics model and carry out crankshaft dynamics calculation to calculate the dynamic characteristics of the range extender under working conditions.

[0040] Step S8: Import the data generated by the dynamic calculation into the fatigue calculation software to carry out the calculation, obtain the fatigue safety factor, and evaluate whether the crankshaft reliability meets the requirements.

[0041] In this embodiment, by adding a motor calculation model built on dynamics calculation software and calibrating the motor model built using both the dynamics calculation software's motor module and professional electromagnetic calculation software, the accuracy of the motor calculation model is effectively improved, ensuring the accuracy of the calculation data. Furthermore, by introducing a motor calculation unit into the crankshaft strength calculation model, electromagnetic load maps under different eccentric distances and parameters for direct-axis and quadrature-axis currents are generated using the basic motor calculation model. Based on the constantly changing dynamic characteristics of the motor load, these loads are applied to the crankshaft reliability calculation model, calculating the dynamic characteristics under the range extender's operating conditions. This yields the impact of the motor load on crankshaft reliability. By comparing the application of magnetic pull before and after, dynamic calculations are performed to determine the degree of influence of the eccentric magnetic pull on the crankshaft fatigue safety factor. This allows for further analysis of the motor load's impact on crankshaft fatigue, facilitating subsequent crankshaft structure design and ensuring that the crankshaft's service life meets design requirements, thus guaranteeing stable engine operation.

[0042] Specifically, in step S1, the input data required for modeling includes the motor's performance parameters, stator and rotor lamination design parameters, winding design parameters, and stator and rotor slicing parameters. The modeling established using the motor parameters in the EMT motor calculation tool can effectively obtain the electromagnetic load results of the motor under different operating conditions.

[0043] Preferably, in step S2, the motor test operating point is taken as the operating point under the rated power of the motor. By using the operating point under the rated power of the motor, it is ensured that the calculated data is taken under normal operating power, and the calculation results of commercial electromagnetic calculation software and the basic calculation model of the motor are comparable.

[0044] Furthermore, in step S3, the commercial electromagnetic calculation software includes Jmag and Mawell. Commercial electromagnetic calculation software can accurately calculate load results. Although commercial electromagnetic calculation software can calculate load results, it cannot generate loads in the format required by AVL dynamics calculation software. Therefore, it can only be used as a reference value for the basic motor calculation model. In order to ensure the accuracy of the EMT motor model in the dynamics calculation software, it can effectively verify whether the load results generated by the basic motor calculation model are accurate, and ensure that the motor load generated by the dynamics calculation software meets the requirements.

[0045] Furthermore, in step S4, when the calculation results of the AVL dynamics calculation software are different from those of the commercial electromagnetic calculation software, the deviation is outside the error range. It is necessary to rebuild the basic calculation model of the motor. After comparison, it is ensured that the established basic calculation model of the motor is accurate, thus ensuring the accuracy of the calculation data.

[0046] Furthermore, in step S5, by performing linear fundamental wave model calculations of the motor, data on motor control parameters, including flux linkage, DC inductance, and AC inductance, are obtained during dynamic calculation and debugging.

[0047] Furthermore, in step S5, the motor operating conditions include operating conditions under different parameters such as motor speed, load, and eccentricity. All load data under the entire motor operating conditions are obtained, and load map files and current map files are generated for real-time iterative calls in subsequent dynamic calculations.

[0048] Furthermore, in step S6, the input data required for crankshaft dynamics calculation includes engine performance parameters, whole engine model, structural parameters of crankshaft and connecting rod mechanism, engine cylinder pressure data, and fuel supply boundary values.

[0049] Furthermore, in step S7, DC and AC calculations are performed to generate electromagnetic load maps under different parameters of direct-axis current and quadrature-axis current. Loading calculations are performed on different electromagnetic load maps, and dynamic calculations are carried out before and after the application of magnetic pull to determine the degree of influence of eccentric magnetic pull on the crankshaft fatigue safety factor, thus providing a basis for the calculation of the crankshaft fatigue safety factor.

[0050] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention, and these will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. A method for calculating the crankshaft strength of a range extender, characterized in that, This calculation method includes the following steps: Step S1: Collect input data for the motor model and build a basic motor calculation model in the EMT motor calculation tool of the AVL dynamics calculation software; Step S2: By setting the motor test operating point, perform electromagnetic calculations on the motor test operating point using the basic motor calculation model, and obtain the electromagnetic load results; Step S3: Build a basic model of the motor in commercial electromagnetic calculation software, and perform electromagnetic calculations for the same motor test conditions as in step S2, and obtain the electromagnetic load results for the test conditions. Step S4: Compare the two load results generated by the EMT motor calculation tool and the commercial electromagnetic calculation software to check whether the calculation results of the AVL dynamics calculation software are accurate; Step S5: Perform electromagnetic calculations for all motor operating conditions, obtain all load data under the entire motor operating conditions, and generate load map files, current map files, and motor control parameters; Step S6: Collect the input data required for crankshaft dynamics calculation and build a crankshaft dynamics calculation model in AVL EXCITE; Step S7: Load the motor load map and current map generated during the motor calculation process into the crankshaft dynamics calculation model. Combine the obtained motor control parameters, debug the dynamics model and carry out crankshaft dynamics calculation to calculate the dynamic characteristics of the range extender under working conditions. Step S8: Import the data generated by the dynamic calculation into the fatigue calculation software to carry out the calculation, obtain the fatigue safety factor, and evaluate whether the crankshaft reliability meets the requirements.

2. The method for calculating the crankshaft strength of a range extender according to claim 1, characterized in that, In step S1, the input data required for modeling includes the motor's performance parameters, stator and rotor lamination design parameters, winding design parameters, and stator and rotor lamination parameters.

3. The method for calculating the crankshaft strength of a range extender according to claim 1, characterized in that, In step S2, the motor test operating point is taken as the operating point under the rated power of the motor.

4. The method for calculating the crankshaft strength of a range extender according to claim 1, characterized in that, In step S3, the commercial electromagnetic calculation software includes Jmag and Mawell.

5. The method for calculating the crankshaft strength of a range extender according to claim 1, characterized in that, In step S4, when the calculation results of the AVL dynamics calculation software are different from those of the commercial electromagnetic calculation software, the deviation is outside the error range, and the basic calculation model of the motor needs to be re-established.

6. The method for calculating the crankshaft strength of a range extender according to claim 1, characterized in that, In step S5, by performing linear fundamental wave model calculations of the motor, data on motor control parameters, including flux linkage, DC inductance, and AC inductance, are obtained during dynamic calculation and debugging.

7. The method for calculating the crankshaft strength of a range extender according to claim 1, characterized in that, In step S5, the motor operating conditions include operating conditions with different parameters such as motor speed, load, and eccentricity.

8. The method for calculating the crankshaft strength of a range extender according to claim 1, characterized in that, In step S6, the input data required for crankshaft dynamics calculation includes engine performance parameters, whole engine model, structural parameters of crankshaft and connecting rod mechanism, engine cylinder pressure data, and fuel supply boundary values.

9. The method for calculating the crankshaft strength of a range extender according to claim 1, characterized in that, In step S7, DC and AC calculations are performed to generate electromagnetic load maps under direct-axis and quadrature-axis currents with different parameters.

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