Range extender crankshaft strength calculation method

Abstract

The invention discloses a method for calculating the strength of a crankshaft of a range extender, belongs to the technical field of crankshafts, and solves the problem that the result is inaccurate when the existing crankshaft of the range extender is subjected to reliability evaluation. The calculation method comprises the steps that a basic motor calculation model is built in AVL dynamics calculation software, electromagnetic calculation of all motor working conditions is carried out, load data is obtained, a load map file, a current map file and motor control parameters are generated, a crankshaft dynamics calculation model is built in AVL EXCITE, and a crankshaft dynamics calculation model is built in AVL EXCITE. And loading data generated in a motor calculation process into a crankshaft dynamic calculation model, carrying out crankshaft dynamic calculation, calculating dynamic characteristics of the range extender under a working condition, importing the dynamic calculation data into fatigue calculation software to carry out calculation, obtaining a fatigue safety coefficient, and evaluating the reliability of the crankshaft. According to the range extender crankshaft strength calculation method, the accuracy of reliability evaluation is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of crankshafts, and in particular to a method for calculating the strength of a range extender crankshaft. Background Art

[0002] The crankshaft is an important engine component, and its reliability has a great impact on the reliability of the engine. The reliability assessment of the crankshaft of the current traditional engine is relatively mature, and the failure rate of the crankshaft caused by design is very low.

[0003] As the country vigorously develops 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 the generator at the flywheel end of the engine to charge the power battery, thereby driving the vehicle to work. The reliability assessment of the range extender crankshaft has become an indispensable task.

[0004] Different from the reliability assessment of crankshafts of traditional engines, the assessment of range extender crankshafts has the following deficiencies:

[0005] (1) When the range extender is working, the center of the motor stator and rotor will deviate due to the influence of vibration, which will generate eccentric magnetic pull on the stator, thus testing the reliability of the crankshaft. The current calculation method cannot take into account the influence of this part of the load.

[0006] (2) When the range extender is working, there is no clear pattern in the trajectory of the rotor eccentricity, that is, the angle and distance of the rotor eccentricity are different under different crankshaft angles, and the size and direction of the eccentric magnetic pull are constantly changing. Therefore, it is necessary to apply motor loads of different sizes and directions in real time according to the actual working conditions of the rotor. That is, this part of the load cannot be loaded in real time at present.

[0007] Due to the influence of the eccentric magnetic pull of the stator and rotor, there is a deviation in the test evaluation results, and it is impossible to obtain accurate evaluation data. During actual use, failures may occur, causing damage to the crankshaft. Summary of the invention

[0008] The technical problem to be solved by the present invention is to provide a method for calculating the strength of a range extender crankshaft in response to the above-mentioned deficiencies in the prior art, provide load data under different working conditions, provide a data basis for reliability evaluation of the range extender crankshaft, ensure the accuracy of the reliability evaluation, and have the characteristics of wide range of use and strong practicality.

[0009] The technical solution adopted by the present invention is: a method for calculating the strength of a range extender crankshaft, the calculation method comprising the following steps:

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

[0011] Step S2: by setting the motor test operating point, performing electromagnetic calculation on the motor test operating point through the motor basic calculation model, and obtaining the electromagnetic load result;

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

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

[0014] Step S5: Carry out electromagnetic calculations for all motor operating conditions, obtain all load data under the entire motor operating condition, 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 in the motor calculation process into the crankshaft dynamics calculation model, combine the obtained motor control parameters, debug the dynamics model and carry out the crankshaft dynamics calculation, and calculate the dynamic characteristics of the range extender under the working condition;

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

[0018] As a further improvement, in the step S1, the input data required for modeling include performance parameters of the motor, design parameters of stator and rotor punching sheets, design parameters of the windings, and slicing parameters of the stator and rotor.

[0019] Furthermore, in the step S2, the motor test operating point is the operating point at 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 result of the AVL dynamic calculation software is different from the calculation result of the commercial electromagnetic calculation software, the deviation is not within the error range, and the basic calculation model of the motor needs to be re-established.

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

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

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

[0025] Furthermore, in the step S7, direct current and alternating current 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) Add the motor calculation model to the dynamic calculation software, and calibrate the motor model built by the motor module in the dynamic calculation software and the professional electromagnetic calculation software, effectively improving the accuracy of the motor calculation model and ensuring the accuracy of the calculation data.

[0029] (2) The motor calculation unit is introduced into the crankshaft strength calculation model. The electromagnetic load map under different eccentricity distances, direct-axis current and quadrature-axis current parameters is generated through the basic motor calculation model. The motor load that changes with the dynamic characteristics is loaded into the crankshaft reliability calculation model. The dynamic characteristics under the working condition of the range extender are calculated, and the influence of the motor load on the crankshaft reliability can be obtained. This can further analyze the influence of the motor load on the crankshaft fatigue, so as to facilitate the subsequent design of the crankshaft structure, thereby ensuring that the service life of the crankshaft meets the design requirements and ensuring the stable operation of the engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the calculation process of the present invention. DETAILED DESCRIPTION

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

[0032] See also Figure 1 A method for calculating the strength of a range extender crankshaft of the present invention is shown, and the calculation method comprises the following steps:

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

[0034] Step S2: by setting the motor test operating point, performing electromagnetic calculation on the motor test operating point through the motor basic calculation model, and obtaining the electromagnetic load result;

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

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

[0037] Step S5: Carry out electromagnetic calculations for all motor operating conditions, obtain all load data under the entire motor operating condition, 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 in the motor calculation process into the crankshaft dynamics calculation model, combine the obtained motor control parameters, debug the dynamics model and carry out the crankshaft dynamics calculation, and calculate the dynamic characteristics of the range extender under the working condition;

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

[0041] In this embodiment, by adding a motor calculation model to the dynamic calculation software, and calibrating the motor model built by the motor module in the dynamic calculation software and the professional electromagnetic calculation software, the accuracy of the motor calculation model is effectively improved, the accuracy of the calculation data is guaranteed, and the motor calculation unit is introduced into the crankshaft strength calculation model. The electromagnetic load map under different eccentric distances, different parameters of direct-axis current and cross-axis current is generated through the basic motor calculation model. The motor load that changes with the dynamic characteristics is loaded into the crankshaft reliability calculation model, and the dynamic characteristics under the working condition of the range extender are calculated. The influence of the motor load on the crankshaft reliability can be obtained. By comparing before and after the magnetic pull is applied, dynamic calculations are carried out to determine the degree of influence of the eccentric magnetic pull on the crankshaft fatigue safety factor. This can further analyze the influence of the motor load on the crankshaft fatigue, so as to facilitate the subsequent design of the crankshaft structure, thereby ensuring that the service life of the crankshaft meets the design requirements and ensuring the stable operation of the engine.

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

[0043] Preferably, in step S2, the motor test operating point is taken as the operating point under the rated power of the motor, and the operating condition under the rated power of the motor is adopted to ensure that the calculation data is taken under the normal operating power, so as to ensure that the calculation results of the commercial electromagnetic calculation software and the basic calculation model of the motor are comparable.

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

[0045] Furthermore, in the step S4, when the calculation results of the AVL dynamic calculation software are different from the calculation results of the commercial electromagnetic calculation software, the deviation is not within the error range, and the basic calculation model of the motor needs to be re-established. After comparison, it is ensured that the established basic calculation model of the motor is accurate, thereby ensuring the accuracy of the calculation data.

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

[0047] Furthermore, in the step S5, the motor operating conditions include the conditions under different parameters of motor speed, load, and eccentric distance, all load data under the entire motor operating condition are obtained, and a load map file and a current map file are generated for real-time iterative calls of subsequent dynamic calculations.

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

[0049] Furthermore, in the step S7, direct current and alternating current calculations are performed to generate electromagnetic load maps under direct-axis current and quadrature-axis current with different parameters, and loading calculations are performed on different electromagnetic load maps. The conditions before and after the magnetic pull is applied are compared, and dynamic calculations are performed to determine the influence of the eccentric magnetic pull on the crankshaft fatigue safety factor, thereby providing a basis for calculating the crankshaft fatigue safety factor.

[0050] The above is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the structure of the present invention, which will not affect the effect of the implementation of the present invention and the practicality of the patent.

Claims

1. A method for calculating the strength of a range extender crankshaft, characterized in that: This calculation method includes the following steps: Step S1: Collect motor model input data and build a basic motor calculation model in the EMT motor calculation tool in the AVL dynamic calculation software; Step S2: by setting the motor test operating point, performing electromagnetic calculation on the motor test operating point through the motor basic calculation model, and obtaining the electromagnetic load result; Step S3: Build a basic model of the motor in commercial electromagnetic calculation software, perform electromagnetic calculations at the same motor test operating point as in step S2, and obtain the electromagnetic load results at the operating point; Step S4: Compare the two load results generated by the EMT motor calculation tool and the model built in the commercial electromagnetic calculation software to detect whether the calculation results of the AVL dynamic calculation software are accurate; Step S5: Carry out electromagnetic calculations for all motor operating conditions, obtain all load data under the entire motor operating condition, 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 in the motor calculation process into the crankshaft dynamics calculation model, combine the obtained motor control parameters, debug the dynamics model and carry out the crankshaft dynamics calculation, and calculate the dynamic characteristics of the range extender under the working condition; Step S8: Import the result data generated by the dynamic calculation into the fatigue calculation software to carry out calculations, obtain the fatigue safety factor and evaluate whether the crankshaft reliability meets the requirements.

2. A method for calculating the strength of a range extender crankshaft according to claim 1, characterized in that: In the step S1, the input data required for modeling include the performance parameters of the motor, the design parameters of the stator and rotor punching sheets, the design parameters of the windings, and the slicing parameters of the stator and rotor.

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

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

5. A method for calculating the strength of a range extender crankshaft according to claim 1, characterized in that: In the step S4, when the calculation result of the AVL dynamic calculation software is different from the calculation result of the commercial electromagnetic calculation software, the deviation is not within the error range, and the basic calculation model of the motor needs to be re-established.

6. A method for calculating the strength of a range extender crankshaft according to claim 1, characterized in that: In the step S5, the linear fundamental wave model of the motor is calculated to obtain data on motor control parameters in dynamic calculation and debugging, including flux linkage, DC inductance, and AC inductance.

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

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

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

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