Engine timing chain reliability evaluation method

Abstract

The application provides a kind of engine timing chain reliability evaluation method, it includes the following steps: selecting two timing chains, detecting the original length of timing chain, and the two timing chains are respectively assembled to two new engines A, B, and then complete the running-in according to the running-in specification;Using engine A to set the failure risk condition of timing chain, soot extreme condition, low temperature idle fuel dilution preset condition;Make engine B run the failure risk condition of timing chain, soot extreme condition, low temperature idle fuel dilution preset condition in turn;Disassemble engine B, take out timing chain, detect the length of timing chain after test, if the difference between the length of timing chain after test and the original length is less than the set value, then the reliability of timing chain meets the requirements, otherwise, it does not meet the requirements.The application can comprehensively evaluate the reliability of timing chain.

Description

Technical Field

[0001] This invention belongs to the field of engine component evaluation technology, specifically relating to a method for evaluating the reliability of engine timing chains. Background Technology

[0002] The timing chain is a key component of the engine timing system, ensuring proper crankshaft and camshaft phasing, as well as normal engine intake, fuel injection, and ignition. Timing chains are typically lubricated with engine oil, and their reliability and wear resistance directly impact engine performance. Abnormal wear or elongation of the timing chain can lead to abnormal combustion, and even valve system malfunctions, valve collisions with pistons, and other hardware damage. Whether the timing chain's reliability meets the requirements of the engine it's paired with requires selection and matching based on the engine's technical characteristics and performance specifications. This necessitates theoretical calculations, simulation analysis, and experimental verification to ensure optimal design and reliable lifespan.

[0003] Engine development involves a series of mechanical development and reliability tests, including stress analysis and tensioner performance tests for the timing chain. However, timing chain reliability testing lacks specific verification and is often included as an adjunct to general engine reliability tests. It rarely considers factors influencing timing chain reliability, and the test conditions are often limited to maximum torque or rated conditions. This results in a one-sided evaluation of timing chain reliability, failing to comprehensively examine its application scenarios and leading to insufficient reliability verification. Therefore, designing a comprehensive reliability evaluation method for engine timing chains is a pressing technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to provide a method for evaluating the reliability of engine timing chains, so as to solve the above-mentioned technical problems in the prior art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for evaluating the reliability of an engine timing chain includes the following steps:

[0007] Step S1: Select two timing chains, check the original length of the timing chains, and assemble the two timing chains into the two new engines A and B respectively. Then, complete the break-in process according to the break-in specifications.

[0008] Step S2: Use engine A to set the failure risk conditions of the timing chain;

[0009] Step S3: Set the extreme soot conditions using engine A;

[0010] Step S4: Use engine A to set the preset operating conditions for low-temperature idling fuel dilution;

[0011] Step S5: Make engine B run the timing chain failure risk condition, soot extreme condition, and low temperature idle speed fuel dilution preset condition in sequence.

[0012] Step S6: Disassemble engine B, remove the timing chain, and test the length of the timing chain after the test. If the difference between the length of the timing chain after the test and the original length is less than the set value, the reliability of the timing chain meets the requirements; otherwise, it does not meet the requirements.

[0013] Preferably, the specific method for setting the failure risk conditions of the timing chain in step S2 is as follows: a sensor is installed on engine A, and a timing chain load test is performed on a test bench. Under engine loads of 10%, 50%, and 100%, the engine speed is uniformly increased from idle speed to rated speed within a set time, and then uniformly decreased from rated speed to idle speed. The corresponding conditions for the maximum load of the timing chain under the three loads are obtained and are denoted as Condition 1, Condition 2, and Condition 3, respectively.

[0014] Preferably, the set time is 60 seconds.

[0015] Preferably, in step S3, the specific method for setting the extreme smoke condition is as follows: using engine A, a universal characteristic test of smoke opacity is conducted to obtain the operating condition corresponding to the maximum smoke opacity of the engine, which is the extreme smoke condition.

[0016] Preferably, in step S4, the method for setting the low-temperature idling fuel dilution preset condition is as follows: using an engine test bench water thermostat, fuel is added to the oil pan of engine A so that the fuel dilution rate of the engine oil reaches 5%, which is the low-temperature idling fuel dilution preset condition.

[0017] Preferably, in step S5, the engine inlet water temperature is set to 95°C under operating conditions one, two, three, and extreme soot conditions; and the engine inlet water temperature is set to 30°C under the low-temperature idling fuel dilution preset condition.

[0018] Preferably, in step S5, the running time for operating condition 1, operating condition 2, operating condition 3, soot extreme value operating condition, and low temperature idling fuel dilution preset operating condition is 4 hours.

[0019] Preferably, in step S5, engine B is run 20 cycles in sequence according to the following conditions: operating condition 1, operating condition 2, operating condition 3, extreme soot condition, and low temperature idling fuel dilution preset condition.

[0020] Preferably, when assembling engine B, pistons and cylinders that enable engine B to have the maximum cylinder clearance are selected, and piston rings with the minimum tangential spring force design value are selected.

[0021] Preferably, the setting value is 0.1% of the original length of the timing chain.

[0022] The beneficial effects of this invention are as follows:

[0023] The engine timing chain reliability evaluation method of the present invention includes multiple operating conditions during reliability testing, and can evaluate the reliability of the timing chain under multiple operating conditions, thereby enabling a more comprehensive evaluation of the timing chain reliability and a more accurate evaluation of the timing chain reliability. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly described below, and the specific embodiments of the present invention will be further described in detail with reference to the drawings, wherein...

[0025] Figure 1 A flowchart of an engine timing chain reliability evaluation method provided in an embodiment of the present invention. Detailed Implementation

[0026] To enable those skilled in the art to better understand the technical solution of the present invention, the present solution will be further described in detail below with reference to specific embodiments.

[0027] like Figure 1 As shown, this embodiment of the invention provides a method for evaluating the reliability of an engine timing chain, which includes the following steps:

[0028] Step S1: Select two timing chains, check the original length of the timing chains, and assemble the two timing chains into the two new engines A and B respectively. Then, complete the break-in process according to the break-in specifications.

[0029] Step S2: Use engine A to set the failure risk conditions of the timing chain;

[0030] Step S3: Set the extreme soot conditions using engine A;

[0031] Step S4: Use engine A to set the preset operating conditions for low-temperature idling fuel dilution;

[0032] Step S5: Make engine B run the timing chain failure risk condition, soot extreme condition, and low temperature idle speed fuel dilution preset condition in sequence.

[0033] Step S6: Disassemble engine B, remove the timing chain, and test the length of the timing chain after the test. If the difference between the length of the timing chain after the test and the original length (i.e., the elongation of the timing chain) is less than the set value, then the reliability of the timing chain meets the requirements; otherwise, it does not meet the requirements.

[0034] The engine timing chain reliability evaluation method provided in this embodiment of the invention includes multiple operating conditions during reliability testing, which can evaluate the reliability of the timing chain under multiple operating conditions, thereby enabling a more comprehensive evaluation of the timing chain reliability and a more accurate evaluation of the timing chain reliability.

[0035] Furthermore, the specific method for setting the failure risk conditions of the timing chain in step S2 is as follows: a sensor is installed on engine A, and a timing chain load test is performed on a test bench. Under engine loads of 10%, 50%, and 100%, the engine speed is uniformly increased from idle speed to rated speed within a set time, and then uniformly decreased from rated speed to idle speed. The corresponding conditions for the maximum load of the timing chain under the three loads are obtained and are denoted as Condition 1, Condition 2, and Condition 3, respectively.

[0036] Preferably, the set time is 60 seconds.

[0037] Specifically, in step S3, the method for setting the extreme soot condition is as follows: using engine A, a universal characteristic test of smoke opacity is conducted to obtain the condition corresponding to the maximum value of engine smoke opacity, which is the extreme soot condition.

[0038] Furthermore, in step S4, the method for setting the low-temperature idling fuel dilution preset condition is as follows: using an engine test bench water thermostat, fuel is added to the oil pan of engine A so that the fuel dilution rate of the engine oil reaches 5%, which is the low-temperature idling fuel dilution preset condition.

[0039] Preferably, in step S5, the engine inlet water temperature is set to 95°C under operating conditions 1, 2, 3, and extreme soot conditions; and the engine inlet water temperature is set to 30°C under the low-temperature idling fuel dilution preset condition.

[0040] Furthermore, in step S5, the running time for operating condition 1, operating condition 2, operating condition 3, soot extreme value operating condition, and low temperature idling fuel dilution preset operating condition is 4 hours.

[0041] Specifically, in step S5, engine B is run 20 cycles in sequence according to the following conditions: Condition 1, Condition 2, Condition 3, extreme soot condition, and low temperature idling fuel dilution preset condition.

[0042] Furthermore, during engine B assembly, pistons and cylinder blocks that enable engine B to have the maximum cylinder clearance are selected, and piston rings with the minimum tangential spring force design value are chosen. This creates conditions where piston leakage reaches extreme values ​​and increases the conditions for soot to enter the engine oil, so as to better test the reliability of the timing chain under extreme soot conditions.

[0043] Specifically, the setting value is 0.1% of the original length of the timing chain.

[0044] Understandably, in step S1, in addition to detecting the length of the timing chain, design parameters such as the weight and center distance of the timing chain can also be detected; during the test, parameters such as engine power, torque, exhaust temperature, oil temperature, and oil pressure can be recorded.

[0045] This invention selects durability conditions based on the stress analysis results of the timing chain, covering multiple failure risk conditions of the timing chain, and can effectively evaluate the reliability of the timing chain in multiple scenarios. This invention also designs a process of adding a certain proportion of fuel to the oil pan to create an oil dilution condition, effectively evaluating the impact of lubrication limit conditions on the reliability of the timing chain. This invention designs an accelerated soot generation condition to simulate the wear scenario during the use of the timing chain, realizing the evaluation of the wear resistance reliability of the timing chain. This invention designs a 400-hour accelerated wear reliability test, accurately evaluating whether the life cycle of the timing chain meets the usage requirements based on the simulated mileage. This invention uses the method of evaluating the elongation or weight of the timing chain to accurately evaluate the reliability of the timing chain.

[0046] Using the timing chain reliability evaluation method of the present invention, it is possible to achieve accurate evaluation of timing chain reliability, comprehensively evaluate the matching performance and usage effect of timing chain, which is beneficial for comprehensive evaluation of timing chain in engine development, so as to effectively avoid market quality problems and engine damage caused by insufficient verification.

[0047] The above are merely preferred embodiments of the present invention. It should be noted that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. Moreover, after reading the contents of the present invention, those skilled in the art can make various modifications or alterations to the present invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A method for evaluating the reliability of an engine timing chain, characterized in that, It includes the following steps: Step S1: Select two timing chains, check the original length of the timing chains, and assemble the two timing chains into the two new engines A and B respectively. Then, complete the break-in process according to the break-in specifications. Step S2: Use engine A to set the failure risk conditions of the timing chain; Step S3: Set the extreme soot conditions using engine A; Step S4: Use engine A to set the preset operating conditions for low-temperature idling fuel dilution; Step S5: Make engine B run the timing chain failure risk condition, soot extreme condition, and low temperature idle speed fuel dilution preset condition in sequence; Step S6: Disassemble engine B, remove the timing chain, and test the length of the timing chain after the test. If the difference between the length of the timing chain after the test and the original length is less than the set value, the reliability of the timing chain meets the requirements; otherwise, it does not meet the requirements. The specific method for setting the failure risk conditions of the timing chain in step S2 is as follows: Install a sensor on engine A, and conduct a timing chain load test on a test bench. Under engine loads of 10%, 50%, and 100%, the engine speed is uniformly increased from idle speed to rated speed within a set time, and then uniformly decreased from rated speed to idle speed. The corresponding conditions for the maximum load of the timing chain under the three loads are obtained and are recorded as Condition 1, Condition 2, and Condition 3, respectively. In step S3, the specific method for setting the extreme soot condition is as follows: using engine A, a universal characteristic test of smoke opacity is conducted to obtain the operating condition corresponding to the maximum value of engine smoke opacity, which is the extreme soot condition. In step S4, the method for setting the low-temperature idling fuel dilution preset condition is as follows: using the engine test bench water thermostat, fuel is added to the oil pan of engine A so that the fuel dilution rate of the engine oil reaches 5%, which is the low-temperature idling fuel dilution preset condition.

2. The engine timing chain reliability evaluation method according to claim 1, characterized in that, The set time is 60 seconds.

3. The engine timing chain reliability evaluation method according to claim 1, characterized in that, In step S5, under operating conditions 1, 2, 3, and extreme soot conditions, the engine inlet water temperature is set to 95°C; under the low-temperature idling fuel dilution preset condition, the engine inlet water temperature is set to 30°C.

4. The engine timing chain reliability evaluation method according to claim 3, characterized in that, In step S5, the running time for operating conditions 1, 2, 3, extreme soot condition, and low temperature idling fuel dilution preset condition is 4 hours.

5. The engine timing chain reliability evaluation method according to claim 4, characterized in that, In step S5, engine B is run 20 cycles in sequence according to the following conditions: Condition 1, Condition 2, Condition 3, extreme soot condition, and low temperature idling fuel dilution preset condition.

6. The engine timing chain reliability evaluation method according to claim 1, characterized in that, When assembling engine B, select pistons and cylinder blocks that enable engine B to have the maximum cylinder clearance, and select piston rings with the minimum tangential spring force design value.

7. The engine timing chain reliability evaluation method according to any one of claims 1 to 6, characterized in that, The setting value is 0.1% of the original length of the timing chain.

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