A life verification method for automobile parts products

Abstract

The present invention provides a life verification method for an automobile component product, and belongs to the technical field of life verification for automobile component products. The method comprises: (1) performing a reliability test on an automobile component product according to standard provisions; the reliability test includes all test items specified in the standard; (2) if the tested product passes all corresponding test items, it is determined that the tested product can reach the design life, and the design life is calculated based on the mileage in the performance corresponding to the reliability test or obtained based on the service life in the performance corresponding to the reliability test. The present invention proposes a life verification method for verifying the life of an automobile component product according to the reliability test results, which does not require a separate accelerated life test to verify the product life, can save test time, and improve test efficiency; and unifies the benchmarks for life verification of the same type of automobile component products, and the life verification results are accurate.

Description

Technical Field

[0001] The invention relates to a life verification method for an automobile component product, and belongs to the technical field of life verification of automobile component products. Background Art

[0002] Lifespan is an essential indicator for the design of automotive parts and is the key basis for whether a product is competitive. How to determine whether the lifespan of automotive parts meets the design requirements and how to evaluate whether automotive parts meet the design requirements in the shortest possible time are the difficulties in the current industry.

[0003] At present, there are two types of tests that need to be done before automotive parts leave the factory. One is the reliability test, which is used to verify whether the reliability of the product meets the design requirements; the other is the life test, which is used to verify whether the life of the product meets the design requirements (that is, whether it can reach the designed life). Currently, there are two types of life tests. The first is the conventional endurance stress life test, which verifies the product's ability to complete the specified functions under the specified conditions of use to obtain the product's life, and the required testing time is long. The second is the accelerated life test, which applies single or multiple stresses to the product to accelerate the exposure of product failure modes, potential failure modes or defects, and uses the accelerated life model to obtain the acceleration factor under single stress or multiple stress conditions. The product's working time under single stress or multiple stress conditions is converted into product life, which can shorten the product life test cycle.

[0004] At present, the domestic industry mostly uses accelerated life testing to verify the product life. Commonly used accelerated life models are: (1) Environmental stress acceleration model - Arrhenius model: aF temperature = exp{(Ea / k)(1 / T0-1 / T1)}, where aF temperature represents the temperature acceleration coefficient, Ea represents the activation energy of precipitation failure, k represents the Bosman constant, T0 represents the temperature at which the product works normally (273+23°C), and T1 represents the temperature at which stress is applied to the product; (2) Electrical stress acceleration model - voltage model: t / tε = (V / Vε)3, where t represents the failure time under conventional stress acceleration test, tε represents the failure time under accelerated life test, V represents the voltage stress applied under conventional conditions, and Vε represents the voltage applied under accelerated test conditions; (3) Mechanical stress acceleration model - inverse power law model (SN) model: A = (S / Sn)a, where S represents normal stress, Sn represents accelerated stress, and a represents the typical value of different materials, such as standard steel a = 6.

[0005] Although accelerated life testing can shorten the test cycle, there are the following problems when using accelerated life testing to verify product life: (1) There are many types of accelerated life models. When performing accelerated life testing on the same product, if the selected accelerated life models are inconsistent, the calculated acceleration factors are often inconsistent, which in turn leads to inconsistent accelerated life test results, or even a large difference, which ultimately leads to low accuracy of life verification results; (2) Even if the accelerated life model adopted is consistent, when the product usage time division is inconsistent under different stresses, the calculated acceleration factor results are also inconsistent, which will also affect the low accuracy of the life verification results; (3) The test conditions of the accelerated life test are greatly affected by the parameter selection of the accelerated life model, which will also affect the calculation of the acceleration factor, and thus affect the accuracy of the life verification results. Summary of the invention

[0006] The purpose of the present invention is to provide a life verification method for an automobile component product, so as to solve the problem that the life verification result obtained by verifying the product life by using an accelerated life test is inaccurate.

[0007] To achieve the above object, the present invention provides a life verification method for an automobile component product, the method comprising the following steps:

[0008] (1) Conduct reliability tests on automotive parts products in accordance with the standards; the reliability tests include all test items specified in the standards;

[0009] (2) If the product under test passes all the corresponding test items, it is determined that the product under test can reach the design life, and the design life is calculated based on the mileage in the performance corresponding to the reliability test or the service life in the performance corresponding to the reliability test.

[0010] The beneficial effects of the present invention are as follows: (1) The present invention proposes a life verification method for verifying the life of an automobile component product based on the reliability test results, based on the fact that the design life of the automobile component product can be calculated based on the mileage in the performance corresponding to the reliability test or based on the service life in the performance corresponding to the reliability test. As long as the reliability test is performed on the automobile component product under test using the test items specified in the standard (such as the national or international standard), it can be known at the same time based on the reliability test results whether the life of the automobile component product under test can reach the design life and whether the reliability of the automobile component product under test meets the design requirements. There is no need to perform accelerated life test separately to verify the product life, which can save test time and improve test efficiency. (2) for the same type of automotive parts products, since the test standards for the test items of this type of products specified in the standard are unified, the benchmark for life verification of this type of products is unified, and there will be no problem of inaccurate life verification results due to inconsistent selected accelerated life models or inconsistent test conditions and test times when using accelerated life tests for product life verification; (3) since the test standards for the test items in the standard can cover about 80% of the use environments of automotive parts products, the life verification results obtained by the life verification method of the present invention are highly representative and accurate; and the life verification method of the present invention can be applied to the life verification of all automotive parts products and has strong versatility.

[0011] Furthermore, in the above-mentioned life verification method for automobile parts products, the reliability test of automobile parts products according to the standard provisions includes: conducting reliability tests in accordance with the standard provisions, or using tightened test conditions and their corresponding test times to replace the test conditions and test times specified in the standard to conduct reliability tests.

[0012] The beneficial effect of doing so is that by tightening the test conditions of the test items, the test time of the corresponding test items can be further shortened and the test efficiency can be improved.

[0013] Furthermore, in the above-mentioned life verification method for automotive parts products, the test time corresponding to the tightened test conditions is obtained by the following steps: selecting a corresponding accelerated life model according to the type of test conditions, calculating the acceleration factor corresponding to the tightened test conditions in combination with the corresponding accelerated life model, and using the calculated acceleration factor and the design life of the product under test to calculate the test time corresponding to the tightened test conditions.

[0014] Furthermore, in the above-mentioned life verification method for automotive parts products, the method also includes a step of verifying whether the life of the product under test can reach the extended design life, and the step includes: for all test items of the product under test specified in the standard, the test time of each test item is linearly extended accordingly; if the product under test can still pass all its corresponding test items, it is determined that the life of the product under test can reach the extended design life; the extended design life is linearly related to the extended test time.

[0015] The beneficial effect of doing this is that when the design life of the product under test is extended, the test stress does not need to be changed. The extended test time corresponding to the extended design life can be calculated directly based on the linear relationship between the extended design life and the extended test time. Then the extended test time is used to replace the test time of the corresponding test items specified in the standard to carry out reliability testing on the product under test. There is no need to calculate again with reference to the accelerated life model, which simplifies the life verification method after the design life is extended.

[0016] Furthermore, in the above-mentioned life verification method for automobile parts products, the standard is GB / T28046 or GB / T31467. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a flow chart of the life verification method of the present invention. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0019] Life verification method embodiment:

[0020] The life verification method of the automobile parts product of this embodiment (hereinafter referred to as the life verification method) is as follows: Figure 1 As shown, the life verification method includes the following steps:

[0021] (1) Conduct reliability tests on automobile parts and components in accordance with the standards, that is, conduct reliability tests on automobile parts and components in accordance with the test standards (test conditions, test time and test methods) specified in the standards; reliability tests include all test items specified in the standards (also called reliability test items);

[0022] (2) If the product under test passes all the corresponding test items, it is determined that the product under test can reach the design life, where the design life is calculated based on the mileage in the performance corresponding to the reliability test or the service life in the performance corresponding to the reliability test.

[0023] Specifically, if the standard stipulates the mileage in the performance corresponding to the reliability test of the product under test, the design life of the product under test will be calculated based on the mileage. At this time, the mileage here refers to the total mileage that the car can travel if the performance of the product under test is qualified. Then, combined with the average daily mileage of the car, the total driving time of the car when the performance of the product under test is qualified can be obtained. The total driving time obtained is the design life of the product under test.

[0024] If the standard stipulates the service life of the performance corresponding to the reliability test of the product under test, the design life of the product under test can be obtained based on the service life. The service life here refers to the total length of time the product under test can be used if the performance of the product under test is qualified. In this case, the service life can be directly used as the design life of the product under test.

[0025] The standard in this embodiment may be a national standard, an international standard, or an industry standard.

[0026] The following research results were obtained through the analysis of a large amount of data: (1) The design life of automotive parts products can be calculated based on the mileage in the performance corresponding to the reliability test items specified in the standard or based on the service life in the performance corresponding to the reliability test; (2) The test conditions and test time of the reliability test items specified in the standard are also converted based on the design life of automotive parts products through the accelerated life model; therefore, for a certain automotive part product, if the product passes all its corresponding reliability test items, it is equivalent to that the life of the product can reach its design life.

[0027] Based on the above research results, a life verification method of the present embodiment for verifying the life of an automobile component product according to the reliability test results is proposed, so that as long as the reliability test is performed on the tested automobile component product using the test items specified in the standard, it is possible to simultaneously know whether the life of the tested automobile component product can reach the design life and whether the reliability of the tested automobile component product meets the design requirements according to the reliability test results, and there is no need to perform accelerated life testing separately to verify the product life, which can save test time and improve test efficiency; for the same type of automobile component products, since the test standards (i.e., test conditions, test time and test methods) of the test items of this type of products specified in the standard are unified, the benchmark for life verification of this type of products is unified, and there will be no problem of inaccurate life verification results due to inconsistent accelerated life models selected or inconsistent test conditions and test times when using accelerated life testing for product life verification; in addition, since the test standards of the test items in the standard can cover about 80% of the use environments of automobile component products, the life verification results obtained by the life verification method of the present embodiment are highly representative and accurate; and the life verification method of the present embodiment can be applied to the life verification of all automobile component products, and has strong versatility.

[0028] Auto parts include engines, transmissions, battery packs, etc. In the standards (such as GB / T28046 or GB / T31467), each product has corresponding reliability test items and test standards for each reliability test item, namely, test conditions, test time and test methods.

[0029] Taking the battery pack as an example, the reliability test items of the battery pack in GB / T31467 include 16 reliability test items such as vibration test, temperature shock test, mechanical shock test, etc. Among them, the test standards of vibration test and temperature shock test are as follows:

[0030] Vibration test: The vibration test is carried out in three directions, starting from the Z axis, then the Y axis, and finally the X axis. The test process refers to GB / T2423.56. The test time in each direction is 21 hours. If there are two test objects, it can be reduced to 15 hours. If there are three test objects, it can be reduced to 12 hours. During the test, the state of the smallest monitoring unit inside the tested object, such as voltage and temperature, is monitored. After the vibration test, it is observed for 2 hours.

[0031] Temperature shock test: The object to be tested is placed in an alternating temperature environment of (-40±2)℃~(85±2)℃. The conversion time between the two extreme temperatures is within 30min. The object to be tested is kept in each extreme temperature environment for 8h and cycled 5 times. After the temperature shock test, observe at room temperature for 2h.

[0032] When the life verification method of this embodiment is used to verify the life of a battery pack, the reliability test is performed on the battery pack according to all reliability test items of the battery pack specified in GB / T31467. If the battery pack passes all corresponding reliability test items, it is determined that the life of the battery pack can reach its design life. The design life of the battery can be calculated based on the mileage in the performance corresponding to any reliability test item or based on the service life in the performance corresponding to any reliability test item.

[0033] For example, if the battery pack passes the vibration test, it means that the vibration performance of the battery pack is qualified. If the standard stipulates that the test time of the battery pack vibration test is 21 hours, the corresponding mileage of the car is 600,000 kilometers, then combined with the average daily mileage of the car (for example, the average daily mileage of a bus is 200 kilometers), the design life of the battery pack can be calculated to be 8 years; or if the standard stipulates that the battery pack vibration performance is qualified, its service life is 8 years, then the design life of the battery pack can be directly obtained as 8 years. In this way, when the battery pack is tested at the factory, there is no need to conduct a separate accelerated life test. As long as the reliability test is conducted, it can be known at the same time whether the life of the battery pack can reach the design life and whether the reliability of the battery pack meets the design requirements. Compared with the existing factory test where both tests must be performed, it can not only save test time and improve test efficiency; in addition, since the test standards in the standard are unified, the benchmark for life verification is also unified, thereby improving the accuracy of the life verification results.

[0034] As another implementation method, the test conditions of the reliability test items in the standard can be tightened, that is, the test stress (such as vibration, temperature, etc.) acting on the tested product can be tightened to further shorten the test time of the corresponding reliability test items and improve the test efficiency. The test time corresponding to the tightened test stress is obtained by the following steps: selecting the corresponding accelerated life model according to the type of test stress, calculating the acceleration factor corresponding to the tightened test stress in combination with the corresponding accelerated life model, and calculating the test time corresponding to the tightened test stress using the calculated acceleration factor and the design life of the product. It is easy to know that the reliability test of the tested product is carried out by replacing the test stress and test time of the corresponding reliability test items specified in the standard with the tightened test stress and its corresponding test time, and the test results obtained are the same, but the required test time is shorter.

[0035] Taking the test stress (temperature stress at this time) in the tightened temperature shock test of the battery pack in GB / T31467 as an example, the temperature stress specified in GB / T31467 is (-40±2)℃~(85±2)℃, and the test time corresponding to the temperature stress is 8h. In order to further shorten the test time, the temperature stress is tightened, for example, the temperature stress after tightening is (-50±2)℃~(95±2)℃, and then the acceleration factor corresponding to the tightened temperature stress is calculated in combination with the temperature accelerated life model, and then the test time corresponding to the tightened temperature stress is calculated in combination with the acceleration factor and the design life of the battery pack. It is easy to know that the test time corresponding to the tightened temperature stress will be shorter than the test time corresponding to the temperature stress specified in the standard.

[0036] As another implementation, after determining that the life of the product under test can reach the design life (for example, 8 years), it is also possible to verify whether the life of the product under test can reach the extended design life (for example, 10 years) through the following steps: for all reliability test items of the product under test specified in the standard, keep the test conditions (i.e., test stress) of each reliability test item unchanged as the test conditions specified in the standard, linearly extend the test time of each reliability test item accordingly, and use the linearly extended test time to replace the test time of the corresponding reliability test item specified in the standard to perform reliability testing on the product under test; when the product under test can still pass all reliability test items, it is determined that the life of the product under test can reach the extended design life.

[0037] Among them, the test time after linear extension of each reliability test item is obtained by the following steps: according to the product life (i.e., failure time) conforming to the linear transformation theory, under the condition that the test stress remains unchanged, the linear conversion relationship between the failure time of the product and the failure time in the accelerated life test (referred to as the linear conversion relationship) is: t0 = εtε, where ε represents the acceleration coefficient, tε represents the failure time in the accelerated life test, which in this embodiment refers to the extended test time, and t0 represents the failure time of the product, which in this embodiment refers to the extended design life. Therefore, substituting the extended design life into the linear conversion relationship, the linearly extended test time corresponding to the extended design life can be obtained. In this way, when the design life of the tested product is extended, the test stress can be unchanged, and the linearly extended test time can be directly calculated according to the linear conversion relationship, and then the linearly extended test time is used to replace the test time of the corresponding reliability test item specified in the standard to perform reliability test on the tested product, without the need to refer to the accelerated life model for recalculation, which simplifies the life verification method after the design life is extended.

[0038] The life verification method of this embodiment is applicable to the test and verification of the calendar life of all automotive parts products, and can be extended to the test and verification of the warranty life and extended warranty life of all automotive parts products, supporting the life reliability evaluation of automotive products of 8 and above.

Claims

1. A life verification method for automobile parts products, characterized in that: The method comprises the following steps: (1) Conduct reliability tests on automotive parts products in accordance with the standards; the reliability tests include all test items specified in the standards; (2) If the product under test passes all the corresponding test items, it is determined that the product under test can reach the design life, which is calculated based on the mileage in the performance corresponding to the reliability test or the service life in the performance corresponding to the reliability test; The method also includes the step of verifying whether the life of the tested product can reach the extended design life after determining that the tested product can reach the design life, and the step includes: for all test items of the tested product specified in the standard, linearly extending the test time of each test item accordingly, if the tested product can still pass all its corresponding test items, it is determined that the life of the tested product can reach the extended design life; the extended design life is linearly related to the extended test time, and the linear relationship is a linear conversion relationship between the failure time of the product and the failure time in the accelerated life test under the condition of unchanged test stress, the extended design life is the failure time of the product, and the extended test time is the failure time in the accelerated life test.

2. The life verification method of an automobile component product according to claim 1, characterized in that: The reliability test of automobile parts products according to the standard provisions includes: conducting reliability tests in accordance with the standard provisions, or using stricter test conditions and their corresponding test times to replace the test conditions and test times specified in the standard to conduct reliability tests.

3. The life verification method of an automobile component product according to claim 2, characterized in that: The test time corresponding to the tightened test conditions is obtained by the following steps: selecting the corresponding accelerated life model according to the type of test conditions, calculating the acceleration factor corresponding to the tightened test conditions in combination with the corresponding accelerated life model, and using the calculated acceleration factor and the design life of the product under test to calculate the test time corresponding to the tightened test conditions.

4. The life verification method of an automobile component product according to claim 1, characterized in that: The standard is GB / T28046 or GB / T31467.

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