A method for generating durability load spectrum of drive system

Abstract

The present invention provides a method for generating a durable load spectrum of a drive system, which includes: determining a user road condition and multiple driving conditions of a test field according to user driving behavior data; collecting load spectrum data of a vehicle under the user road condition, and calculating gear and bearing damage of the user road condition under a target mileage; collecting load spectrum data of a vehicle under multiple driving conditions of a test field, and calculating gear and bearing damage of multiple driving conditions of the test field; calculating the current damage ratio of gears and bearings according to the gear and bearing damage of the user road condition and multiple driving conditions of the test field, and if the current damage ratio does not meet the constraint conditions, compiling an optimization program to re-optimize the number of cycles of the driving condition of the test field, and if it meets the constraint conditions, obtaining the load spectrum of the durable condition of the test field. The present invention can quickly and accurately formulate a durable load spectrum of a vehicle drive system, and accurately reflect the damage caused by the load to the gears and bearings.

Description

Technical Field

[0001] The present invention relates to the technical field of compiling a durable load spectrum of a drive system, and in particular to a method for generating a durable load spectrum of a drive system. Background Art

[0002] In the automotive design and verification stage, in order to avoid "excessive" or "inadequate" product service life, it is necessary to consider the user's usage requirements. Therefore, the durability test specifications formulated should be related to the user's usage requirements. At present, the user-related technology based on the strength of the body structure is relatively mature, but the user-related technology based on the power drive system is not yet mature.

[0003] At present, for traditional automobiles, the "pseudo-damage" method is often used to characterize the correlation between the test load spectrum and the user working conditions. That is, without considering the specific structure, various load signals such as force, torque, displacement, acceleration, strain, stress, etc. are directly regarded as generalized stress, and generalized stress is used as input. The specified standard SN curve is used to perform cycle counting and damage accumulation to obtain pseudo-damage. The durability assessment of electric vehicle drive systems in the industry often follows the above-mentioned specifications for traditional automobiles.

[0004] However, electric vehicles are obviously different from traditional vehicles in terms of assembly structure and usage. The drive system of electric vehicles mainly includes motors, gears, bearings, shafts and other components. During the driving process of the vehicle, not only the magnitude of the motor torque changes frequently, but also the direction of the motor torque changes frequently during the driving and braking energy recovery process, which causes the gears and bearings to undergo complex load changes. For example, when the direction of the motor torque changes, the loaded tooth surface of the gear will change, and the axial load borne by the bearing will also change. Pseudo-damage is calculated directly using load signals such as torque, and the standard SN curve used is not the SN curve of the actual structure, so it is difficult to accurately reflect the damage caused by the load to the gears and bearings, and it cannot be used to determine whether the damage to the parts exceeds the life requirements of the parts themselves.

[0005] Therefore, there is an urgent need for a method to compile a durability load spectrum for electric vehicle drive systems, which can clearly correlate the durability conditions of the test site with the user's road conditions and accurately reflect the damage caused by the load to gears and bearings. Summary of the invention

[0006] In view of the above problems, the purpose of the present invention is to provide a method for generating a durability load spectrum of a drive system, which can quickly and accurately formulate a durability load spectrum of an electric vehicle drive system, can establish a clear correlation between the durability conditions of a test site and the user's road conditions, and can accurately reflect the damage caused by the load to gears and bearings.

[0007] An embodiment of the present invention provides a method for generating a durability load spectrum of a drive system, comprising:

[0008] Determine the user's road conditions and various driving conditions on the test site through statistical analysis of the user's driving behavior big data;

[0009] Collecting load spectrum data of the vehicle under the user road condition, and calculating gear and bearing damage under the user road condition under a preset target mileage according to the load spectrum data under the user road condition;

[0010] Collecting load spectrum data of the vehicle under various driving conditions at the test site, and calculating the gear and bearing damage under various driving conditions at the test site according to the set number of cycles of the various driving conditions at the test site;

[0011] Calculate the current damage ratio of gears and bearings based on the gear and bearing damage of the user's road conditions and the gear and bearing damage of various driving conditions on the test field;

[0012] Determine whether the current damage ratio of gears and bearings meets the preset constraints;

[0013] If yes, obtaining a load spectrum of the endurance condition of the test field according to the current cycle number of the multiple driving conditions of the test field; wherein the endurance condition of the test field includes multiple driving conditions of the test field;

[0014] If not, reset the number of cycles of various driving conditions in the test field and recalculate the damage ratio of gears and bearings under this number of cycles.

[0015] As an improvement of the above solution, the load spectrum data includes: data on changes in wheel-end half-shaft torque, motor torque, and motor speed over time.

[0016] As an improvement of the above scheme, the various driving conditions in the test field include: starting condition, low-speed shifting condition, medium-speed shifting condition, medium-high speed shifting condition, high-speed shifting condition, and continuous high-speed condition.

[0017] As an improvement of the above solution, according to the load spectrum data under the user road condition, the gear and bearing damage under the user road condition under the preset target mileage is calculated, including:

[0018] According to the load spectrum data of the user's road condition and the preset target mileage, the gear damage and bearing damage when driving the target mileage under the user's road condition are calculated through a pre-established drive system simulation model.

[0019] As an improvement of the above solution, the constraint condition is that the current damage ratio of the gear and the current damage ratio of the bearing both fall within a preset numerical range.

[0020] As an improvement to the above solution, the resetting of the number of cycles of various driving conditions in the test field includes:

[0021] Set the current cycle number of various driving conditions in the test field, and calculate the gear damage and bearing damage under the current cycle number of various driving conditions in the test field;

[0022] Calculate the current damage ratio of each gear according to the gear damage under the user's road conditions and the gear damage under the current number of cycles under various driving conditions of the test field;

[0023] Calculate the current damage ratio of each bearing according to the bearing damage under the user's road conditions and the bearing damage under the current number of cycles under various driving conditions in the test field;

[0024] Calculating the damage ratio deviation of the bearing according to the current damage ratio of each bearing and a preset bearing damage ratio target value;

[0025] Calculating the gear damage ratio deviation according to the current damage ratio of each gear and a preset gear damage ratio target value;

[0026] Performing weighted summation on the damage ratio deviation of the gear and the damage ratio deviation of the bearing to obtain the weighted damage ratio total deviation;

[0027] The number of cycles of various driving conditions in the test field is reset to obtain the number of cycles corresponding to the minimum total deviation of the weighted damage ratio as the final number of cycles.

[0028] As an improvement of the above solution, according to the current damage ratio of each bearing and a preset bearing damage ratio target value, the damage ratio deviation of the bearing is calculated, including:

[0029] According to the bearing damage ratio deviation calculation formula calculating a damage ratio deviation of the bearing;

[0030] Among them, R bi =D bi / D ub , D ub Indicates the bearing damage under user road conditions, D bi Indicates the bearing damage under various driving conditions in the test field, D bk represents the bearing damage under the kth driving condition, s represents the number of driving conditions, R bt Indicates the target value of bearing damage ratio, R bi represents the current damage ratio of the i-th bearing, and n represents the number of bearings.

[0031] As an improvement of the above solution, the damage ratio deviation of the gear is calculated according to the current damage ratio of each gear and the preset gear damage ratio target value, including:

[0032] According to the gear damage ratio deviation calculation formula calculating a damage ratio deviation of the gear;

[0033] Among them, R gj =D gj / D ug , D ug Indicates the gear damage under user road conditions, D gj represents the gear damage under various driving conditions in the test field, R gt Indicates the gear damage ratio target value, R gj represents the damage ratio of the jth gear, and m represents the number of gears.

[0034] As an improvement of the above solution, weighted summation is performed on the damage ratio deviation of the gear and the damage ratio deviation of the bearing to obtain the weighted total damage ratio deviation, including:

[0035] According to the following calculation formula for the total deviation of weighted damage ratio of bearings and gears, calculate the total deviation of weighted damage ratio

[0036]

[0037] Among them, W b and W g are the weights of the bearings and gears respectively.

[0038] Compared with the prior art, the beneficial effect of the embodiment of the present invention is that: the method for generating the durable load spectrum of the drive system includes: determining the user road conditions according to the statistical analysis of the user driving behavior big data, and preliminarily determining the multiple driving conditions of the test field; collecting the load spectrum data of the vehicle under the user road conditions and the test field road conditions, and calculating the current damage ratio of the gears and bearings; judging whether the current damage ratio of the gears and bearings meets the preset constraints; if not, constructing an optimization program, resetting the number of cycles of the multiple driving conditions of the test field, and recalculating the current damage ratio of the gears and bearings under the number of cycles; if so, obtaining the load spectrum of the durable conditions of the test field according to the number of cycles of the multiple driving conditions of the test field. Based on the damage ratio of the gears and bearings of the drive system under the user road conditions and the durable conditions of the test field, a clear equivalent relationship between the durable conditions of the test field and the user road conditions can be guaranteed, avoiding the problem of the durability conditions of the test field being too strict or too loose, and being able to quickly and accurately formulate the durable load spectrum of the electric vehicle drive system, accurately reflecting the damage caused by the load to the gears and bearings. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the implementation mode will be briefly introduced below. Obviously, the drawings described below are only some implementation modes of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 It is a flow chart of a method for generating a durable load spectrum of a drive system provided by the present invention;

[0041] Figure 2 It is a flow chart of compiling the durable load spectrum of the drive system provided by the present invention. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] See also Figure 1 , which is a flow chart of a method for generating a durable load spectrum of a drive system provided by an embodiment of the present invention, the method for generating a durable load spectrum of a drive system comprising:

[0044] S11: Determine the user's road conditions and various driving conditions on the test site through statistical analysis of the user's driving behavior big data;

[0045] S12: collecting load spectrum data of the vehicle under the user road condition, and calculating gear and bearing damage under the user road condition under a preset target mileage according to the load spectrum data under the user road condition;

[0046] S13: collecting load spectrum data of the vehicle under various driving conditions in the test field, and calculating gear and bearing damage under various driving conditions in the test field according to the set number of cycles of the various driving conditions in the test field;

[0047] The specific steps are as follows:

[0048] According to the number of cycles of the endurance sub-conditions in the set test field, the total damage of each bearing under all sub-conditions is calculated. bi Defined as:

[0049]

[0050] Among them, i represents different bearings, k represents different sub-conditions, and s is the number of sub-conditions.

[0051] According to the number of cycles of the endurance test sub-conditions, the total damage of each gear under all sub-conditions is calculated. gj Defined as:

[0052]

[0053] Among them, j represents different gears, k represents different sub-operating conditions, and s is the number of sub-operating conditions.

[0054] The load spectrum data includes: data on changes in wheel end half-shaft torque, motor torque, and motor speed over time.

[0055] The endurance sub-condition of the test field includes various driving conditions of the test field, and the various driving conditions of the test field include: starting condition, low-speed shifting condition, medium-speed shifting condition, medium-high-speed shifting condition, high-speed shifting condition, and continuous high-speed condition.

[0056] Exemplarily, for a certain electric car, the user driving behavior data of users across the country are collected, and the user driving behavior data include but are not limited to the average speed, sudden acceleration / 1,000 kilometers, sudden braking / 1,000 kilometers, sharp turns, number / frequency of lane changes, frequency of speed changes, idling time, etc., driving environment road type, mileage of various terrains, driving time of various terrains, parking time of various terrains, etc. Then the user driving behavior data is analyzed by big data to obtain the statistical data of user usage road conditions and the statistical data of various driving conditions of the vehicle. The statistical data of user usage road conditions include the proportion of highways, urban roads, general roads, and mountain roads across the country, as well as the sales distribution data of vehicles across the country. According to the statistical proportion of highways, urban roads, general roads, and mountain roads, the vehicle is actually driven under the above-mentioned various road conditions in multiple cities across the country, and the load spectrum data of the vehicle when it is actually driven under the user road conditions is collected, and the user road target mileage is set, for example, set to 240,000 kilometers, and a drive system simulation model is established to calculate the damage of each gear and each bearing of the vehicle under the user road condition. At the same time, through statistical analysis of user driving behavior big data, various driving conditions of the test site are formulated; then the load spectrum data of the vehicle under a single cycle number of various driving conditions in the test site is collected, and based on the preset number of cycles of various driving conditions in the test site, the current damage of gears and bearings in each driving condition in the durability condition of the test site is calculated.

[0057] S14: Calculate the current damage ratio of the gear and the bearing according to the gear and bearing damage of the user's road working condition and the gear and bearing damage of various driving working conditions of the test field;

[0058] The damage ratio is defined as: durability test condition damage / user road condition damage. It can be expressed as:

[0059] R b =D b / D ub R g =D g / D ug

[0060] Among them, R b Represents the bearing damage ratio; R g Represents the gear damage ratio; D ub Represents the damage of the bearing under user conditions; D ug Represents the damage of the gear under user conditions; D b Represents the damage of the bearing under the endurance test condition; D g Represents the damage of the gear under the endurance test conditions.

[0061] S15: judging whether the current damage ratio of the gear and the bearing meets the preset constraint conditions;

[0062] S16: If not, reset the number of cycles of various driving conditions in the test field, and recalculate the damage ratio of the gears and bearings under the number of cycles.

[0063] If the current damage ratio of gears and bearings does not meet the preset constraints, an optimization program is constructed to reset the number of cycles of various driving conditions in the test field to ensure that the damage ratio of gears and bearings meets the preset constraints and minimize the weighted total deviation of the damage ratio of gears and bearings.

[0064] S17: If yes, obtain the load spectrum of the durability condition of the test field according to the number of cycles of the various driving conditions of the test field; wherein the durability condition of the test field includes various driving conditions of the test field.

[0065] The constraint condition is that the current damage ratio of the gear and the current damage ratio of the bearing both fall within the preset numerical range. The damage ratio range is generally set to about 1, and can also be set to different values ​​as needed. For example: the damage ratio numerical range is set to (0.8, 1.2). Based on the gear damage and bearing damage under the user's road conditions and the gear damage and bearing damage under the set number of cycles of various driving conditions in the test field, the current damage ratio of the gear and bearing is calculated; if the current damage ratio of the gear and bearing falls within the range of (0.8, 1.2), it indicates that the current damage ratio of the gear and bearing is reasonable, and the current number of test field conditions can be directly used to construct the load spectrum of the test field durability conditions; if the current damage ratio of the gear and bearing is not within the range of (0.8, 1.2), it indicates that the current damage ratio of the gear and bearing is unreasonable, and it is necessary to reset the number of cycles of each driving condition in the test field, and recalculate the current damage ratio of the gear and bearing under the number of cycles, so that the current damage ratio of the gear and bearing under the reset number of cycles is within the range of (0.8, 1.2).

[0066] For example, the number of cycles of the starting condition, low-speed shifting condition, medium-speed shifting condition, medium-high-speed shifting condition, high-speed shifting condition, and continuous high-speed condition are set to 2400 times, 2400 times, 1800 times, 1800 times, 1200 times, and 1200 times, respectively.

[0067] According to the current damage ratio of each bearing and the preset bearing damage ratio target value, the damage ratio deviation of the bearing is calculated:

[0068] The total deviation of bearing damage ratio is defined as:

[0069] Among them, σ b is the total deviation of bearing damage ratio; n is the number of bearings. bt Indicates the target value of bearing damage ratio; R bi represents the current damage ratio of the i-th bearing.

[0070] According to the current damage ratio of each gear and the preset gear damage ratio target value, the damage ratio deviation of the gear is calculated:

[0071] The total deviation of gear damage ratio is defined as:

[0072] Among them, σ g is the total deviation of gear damage ratio; m is the number of gears. gt Indicates the target value of gear damage ratio; R gj represents the damage ratio of the jth gear.

[0073] The damage ratio deviation of the gear and the damage ratio deviation of the bearing are weightedly summed to obtain the weighted total damage ratio deviation:

[0074] Construct the weighted total deviation function of the damage ratio of bearings and gears and calculate the weighted total deviation of the damage ratio σ w Defined as:

[0075]

[0076] Among them, W b and W g They are the weights of bearings and gears respectively. If you want the damage ratio of the gear to be closer to the corresponding damage ratio target value relative to the damage ratio of the bearing, the weight of the gear can be set to be greater than the weight of the bearing; if you want the damage ratio of the bearing to be closer to the corresponding damage ratio target value relative to the damage ratio of the gear, the weight of the bearing can be set to be greater than the weight of the gear; in addition, the weights of the bearing and gear can be set to the same size, for example, both are set to 1.

[0077] The number of cycles corresponding to the minimum total deviation of the weighted damage ratio is obtained as the final number of cycles of the reset load spectrum.

[0078] Compared with the prior art, the beneficial effects of the embodiments of the present invention are:

[0079] 1. A method for compiling the durability load spectrum of the drive system is provided, which can quickly and accurately formulate the load spectrum.

[0080] 2. It can ensure that there is a clear equivalence relationship between the durability conditions of the test site and the user's road conditions, avoiding the problem of the durability test conditions being too strict or too loose, thereby avoiding the cost increase caused by the overly conservative product design of the drive system or the market quality problems caused by insufficient design strength.

[0081] 3. It can provide clear mileage for after-sales service of the whole vehicle or maintenance of related parts.

[0082] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for generating a durability load spectrum of a drive system, It is characterized in that include: Determine the user's road conditions and various driving conditions on the test site through statistical analysis of the user's driving behavior big data; Collecting load spectrum data of the vehicle under the user road condition, and calculating gear and bearing damage under the user road condition under a preset target mileage according to the load spectrum data under the user road condition; Collecting load spectrum data of the vehicle under various driving conditions at the test site, and calculating the gear and bearing damage under various driving conditions at the test site according to the set number of cycles of the various driving conditions at the test site; Calculate the current damage ratio of gears and bearings based on the gear and bearing damage of the user's road conditions and the gear and bearing damage of various driving conditions on the test field; Determine whether the current damage ratio of gears and bearings meets the preset constraints; If yes, obtaining a load spectrum of a durability condition of the test field according to the current cycle number of the multiple driving conditions of the test field; wherein the durability condition of the test field includes multiple driving conditions of the test field; If not, reset the number of cycles of various driving conditions in the test field and recalculate the damage ratio of gears and bearings under the number of cycles; The resetting of the number of cycles of various driving conditions in the test field includes: Set the current cycle number of various driving conditions in the test field, and calculate the gear damage and bearing damage under the current cycle number of various driving conditions in the test field; Calculate the current damage ratio of each gear according to the gear damage under the user's road conditions and the gear damage under the current number of cycles under various driving conditions of the test field; Calculate the current damage ratio of each bearing according to the bearing damage under the user's road conditions and the bearing damage under the current number of cycles under various driving conditions in the test field; Calculating the damage ratio deviation of the bearing according to the current damage ratio of each bearing and a preset bearing damage ratio target value; Calculating the gear damage ratio deviation according to the current damage ratio of each gear and a preset gear damage ratio target value; Performing weighted summation on the damage ratio deviation of the gear and the damage ratio deviation of the bearing to obtain a weighted damage ratio total deviation; The number of cycles of various driving conditions in the test site is reset to obtain the number of cycles corresponding to the minimum total deviation of the weighted damage ratio as the final number of cycles.

2. The method for generating a durability load spectrum of a drive system according to claim 1, It is characterized in that The load spectrum data includes: data on changes in wheel end half-shaft torque, motor torque, and motor speed over time.

3. The method for generating a durability load spectrum of a drive system according to claim 1, It is characterized in that The various driving conditions in the test field include: starting condition, low-speed shifting condition, medium-speed shifting condition, medium-high speed shifting condition, high-speed shifting condition, and continuous high-speed condition.

4. The method for generating a durability load spectrum of a drive system according to claim 1, It is characterized in that According to the load spectrum data under the user road condition, the gear and bearing damage under the user road condition under the preset target mileage is calculated, including: According to the load spectrum data of the user's road condition and the preset target mileage, the gear damage and bearing damage when driving the target mileage under the user's road condition are calculated through a pre-established drive system simulation model.

5. The method for generating a durable load spectrum of a drive system according to claim 1, It is characterized in that The constraint condition is that the current damage ratio of the gear and the current damage ratio of the bearing both fall within a preset value range.

6. The method for generating a durability load spectrum of a drive system according to claim 1, It is characterized in that The step of calculating the bearing damage ratio deviation according to the current damage ratio of each bearing and a preset bearing damage ratio target value comprises: According to the bearing damage ratio deviation calculation formula , calculate the damage ratio deviation of the bearing; in, R bi = D bi / D ub , , Indicates bearing damage under user road conditions, Indicates bearing damage under various driving conditions in the test field. represents the bearing damage under the kth driving condition, s represents the number of driving conditions, Indicates the target value of bearing damage ratio, represents the current damage ratio of the i-th bearing, and n represents the number of bearings.

7. The method for generating a durability load spectrum of a drive system according to claim 6, It is characterized in that The step of calculating the gear damage ratio deviation according to the current damage ratio of each gear and the preset gear damage ratio target value comprises: According to the gear damage ratio deviation calculation formula calculating a damage ratio deviation of the gear; in, R gj = D gj / D ug , , D ug Indicates gear damage under user road conditions, D gj Indicates gear damage under various driving conditions in the test field. D gk represents the gear damage under the kth driving condition, R gt Indicates the gear damage ratio target value, R gj represents the damage ratio of the jth gear, and m represents the number of gears.

8. The method for generating a durable load spectrum of a drive system according to claim 7, wherein the weighted sum of the damage ratio deviation of the gear and the damage ratio deviation of the bearing is performed to obtain the weighted total damage ratio deviation. include: According to the following calculation formula for the total deviation of weighted damage ratio of bearings and gears, calculate the total deviation of weighted damage ratio in, w b and w g are the weights of the bearings and gears respectively.

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