Method for testing an engine valve train

Abstract

The application provides a kind of detection method of engine valve train.The method comprises: measuring the size of the corresponding parts of the unassembled engine valve train, obtaining the first data set of the parts;Assembling the engine with the unassembled parts, obtaining the engine to be tested;Control the engine to be tested to run at a first predetermined condition, under the first predetermined condition, the contact stress of the camshaft of the engine exceeds the predetermined stress;Control the engine to be tested to run at a second predetermined condition, under the second predetermined condition, the speed of the engine changes according to the predetermined control strategy;Disassemble the engine to be tested, and measure the size of the corresponding parts of the disassembled valve train, obtain the second data set of the parts;Based on the first data set and the second data set, obtain the detection result representing the wear of the valve train.In this way, it is helpful to shorten the test cycle, and it is helpful to find / verify the wear abnormality of the engine valve train in the early stage of engine development.

Description

Technical Field

[0001] This invention relates to the field of engine technology, and more specifically, to a method for testing engine valve train mechanisms. Background Technology

[0002] The engine is the heart of a car, and the valve train is a crucial component of it. It mainly consists of valves, camshafts, valve guides, tappets, and other parts. The valve train's function is to open and close the intake and exhaust valves at appropriate times according to the power stroke order and the requirements of each cylinder's working cycle, thus facilitating air exchange in the engine. During operation, the engine's valve train is in a state of high-speed rotation or reciprocating motion, with relatively poor lubrication conditions, making it prone to wear and damage to components. This can lead to problems such as improper valve closure, abnormal noises, valve timing misalignment, and cylinder leakage, resulting in decreased engine performance, increased fuel consumption, and in severe cases, engine failure.

[0003] Currently, engine bench endurance testing can be used to roughly detect the wear of the valve train. However, the results obtained by this method differ significantly from those obtained through vehicle road testing, which takes a long time, typically exceeding two months. In other words, current methods for testing the valve train are not suitable for detecting / verifying related anomalies in the engine valve train during the early stages of engine development. Summary of the Invention

[0004] In view of this, the purpose of this application is to provide a method for detecting engine valve train mechanisms, which can improve the problem that it is not convenient to detect / verify related anomalies of engine valve train mechanisms in the early stages of engine development.

[0005] To achieve the above technical objectives, the technical solution adopted in this application is as follows:

[0006] This application provides a method for detecting an engine valve train, the method comprising:

[0007] The dimensions of the components corresponding to the unassembled engine valve train are measured to obtain the first dataset of the components;

[0008] According to the engine assembly strategy, the unassembled parts are assembled to obtain the engine to be tested;

[0009] The engine under test is controlled to operate under a first preset operating condition, wherein, under the first preset operating condition, the contact stress of the engine's camshaft exceeds a preset stress;

[0010] The engine under test is controlled to operate under a second preset operating condition, wherein the engine speed changes according to a preset control strategy under the second preset operating condition;

[0011] When the engine under test completes the first preset operating condition and the second preset operating condition, the engine under test is disassembled, and the dimensions of the components corresponding to the disassembled valve train are measured to obtain the second dataset of the components.

[0012] Based on the first dataset and the second dataset, detection results characterizing the wear of the valve train are obtained.

[0013] In some optional implementations, controlling the engine under test to operate under a first preset condition includes:

[0014] Based on the pre-established relationship curve between camshaft contact stress and engine speed, the target speed n corresponding to the maximum contact stress in the relationship curve is selected;

[0015] The engine under test is controlled to run at the target speed n and a preset speed fluctuation range for a preset time, the preset time being the time corresponding to the completion of the first specified distance in the simulated vehicle road test.

[0016] In some alternative implementations, the method further includes, prior to dimensional measurement of the components corresponding to the unassembled engine valve train:

[0017] A finite element model corresponding to the engine under test is created using finite element analysis tools;

[0018] The finite element analysis tool is used to generate a curve showing the change of contact stress of the camshaft in the finite element model as a function of engine speed, which is used as the relationship curve.

[0019] In conjunction with the first aspect, in some alternative embodiments, the method further includes, before dimensionally measuring the components corresponding to the unassembled engine valve train:

[0020] Obtain the complete road spectrum of the engine under test, and divide the speed variation range of the engine under test into d segments, where d is an integer greater than 1;

[0021] Based on the complete road spectrum, the operating condition with the largest rate of change of each speed segment in segment d during the speed increase of the engine under test is determined as the acceleration sub-operating condition, and the acceleration sub-operating conditions corresponding to all speed segments in segment d are combined into an acceleration condition.

[0022] Based on the complete road spectrum, the operating condition with the largest rate of change of each speed segment in segment d during the speed reduction process of the engine under test is determined as the deceleration sub-operating condition, and the deceleration sub-operating conditions corresponding to all speed segments in segment d are combined into a deceleration operating condition.

[0023] In some optional implementations, controlling the engine under test to operate under a second preset condition includes:

[0024] The engine under test is controlled to operate cyclically under the acceleration condition and the deceleration condition.

[0025] In some optional implementations, controlling the engine under test to operate cyclically in the acceleration condition and the deceleration condition includes:

[0026] The engine under test is controlled to operate cyclically under the acceleration condition and the deceleration condition. During the cyclic operation, when the engine speed is at the maximum speed or the minimum speed, the maximum speed or the minimum speed is maintained for a first specified duration. When the current number of cycles is an integer multiple of M, when the engine under test has completed the current number of cycles, the engine under test is controlled to operate at the maximum speed for a second specified duration, where the second specified duration is longer than the first specified duration, and M is an integer greater than 1.

[0027] In some alternative implementations, before controlling the engine under test to operate at a first preset condition, the method further includes:

[0028] The engine under test is controlled to run for a third specified period of time in order to break in the engine under test.

[0029] In some optional implementations, based on the first dataset and the second dataset, detection results characterizing the wear of the valve train are obtained, including:

[0030] The wear value of each component in the valve train is obtained based on the data in the first dataset and the second dataset.

[0031] The test results of the valve train are obtained based on the wear value of each component.

[0032] In some optional implementations, the method further includes:

[0033] When the wear value of any component exceeds the corresponding preset threshold, the control alarm module issues an alarm prompt indicating abnormal wear of the component.

[0034] In some alternative embodiments, the components include at least one of the following: camshaft, roller rocker arm, mechanical tappet, hydraulic tappet assembly, timing chain assembly, timing chain guide, timing chain moving guide, camshaft guide, crankshaft timing sprocket, tensioner, intake phaser assembly, exhaust phaser assembly, valve, valve guide, valve seat, valve spring, valve spring seat, valve spring base, and valve lock block.

[0035] The invention employing the above technical solution has the following advantages:

[0036] In the technical solution provided in this application, the dimensions of the components corresponding to the unassembled engine valve train are measured to obtain a first dataset of the components. Then, the unassembled components are assembled to obtain the engine under test. The engine under test is controlled to operate under a first preset condition, wherein the contact stress of the engine camshaft exceeds a preset stress. The engine under test is then controlled to operate under a second preset condition, wherein the engine speed varies according to a preset control strategy. After the engine under test completes the operation under the first and second preset conditions, the engine is disassembled, and the dimensions of the components corresponding to the disassembled valve train are measured to obtain a second dataset of the components. Thus, by controlling the engine camshaft to operate under high contact stress conditions and controlling the engine to operate under varying speed conditions, it is beneficial to measure the wear of the engine valve train under extreme environments in a short period of time, which helps to shorten the testing cycle and, consequently, facilitates the detection / verification of abnormal wear in the engine valve train during the early stages of engine development. Attached Figure Description

[0037] This application can be further illustrated by the non-limiting embodiments given in the accompanying drawings. It should be understood that the following drawings only illustrate some embodiments of this application and should not be considered as limiting the scope. For those skilled in the art, other related drawings can be obtained from these drawings without any inventive effort.

[0038] Figure 1 This is a flowchart illustrating the detection method for the engine valve train provided in an embodiment of this application.

[0039] Figure 2 This is a schematic diagram of the relationship between camshaft contact stress and engine speed provided in an embodiment of this application.

[0040] Figure 3a This is one of the schematic diagrams of the engine speed acceleration condition segment extracted from the complete road spectrum, provided in an embodiment of this application.

[0041] Figure 3b This is the second schematic diagram of the engine speed acceleration condition segment extracted from the complete road spectrum, provided in an embodiment of this application.

[0042] Figure 4a This is one of the schematic diagrams of the engine speed reduction condition segment extracted from the complete road spectrum, provided in an embodiment of this application.

[0043] Figure 4bThis is the second schematic diagram of the engine speed reduction condition segment extracted from the complete road spectrum, provided in an embodiment of this application.

[0044] Figure 5 This is a schematic diagram of the running-in conditions of the engine under test provided in an embodiment of this application.

[0045] Figure 6 This is a schematic diagram of the engine under test in the first preset operating condition, provided as an embodiment of this application.

[0046] Figure 7 This is a schematic diagram of the engine under test in a second preset operating condition, provided as an embodiment of this application. Detailed Implementation

[0047] The present application will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that similar or identical parts are referred to by the same reference numerals in the drawings or description. Implementations not shown or described in the drawings are forms known to those skilled in the art. In the description of this application, terms such as "first" and "second" are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0048] Please refer to Figure 1 This application provides a method for testing an engine valve train. The steps of this method can be performed manually or by corresponding automated equipment; no specific limitation is made on the subject performing the steps. The testing method may include the following steps:

[0049] Step 110: Dimensionally measure the components corresponding to the unassembled engine valve train to obtain the first dataset of the components;

[0050] Step 120: According to the engine assembly strategy, assemble the unassembled parts to obtain the engine to be tested;

[0051] Step 130: Control the engine under test to operate under a first preset operating condition, wherein, under the first preset operating condition, the contact stress of the engine's camshaft exceeds a preset stress;

[0052] Step 140: Control the engine under test to operate under a second preset operating condition, wherein, under the second preset operating condition, the engine speed changes according to a preset control strategy;

[0053] Step 150: When the engine under test completes the first preset operating condition and the second preset operating condition, the engine under test is disassembled, and the dimensions of the components corresponding to the disassembled valve train are measured to obtain the second dataset of the components.

[0054] Step 160: Based on the first dataset and the second dataset, obtain the detection results characterizing the wear of the valve train mechanism.

[0055] The following is a detailed explanation of each step in the testing method for the engine valve train:

[0056] Prior to step 110, the method may include determining control quantities corresponding to a first preset operating condition and a second preset operating condition. These control quantities may include the engine speed corresponding to the maximum contact stress on the camshaft, the rate of change of the engine's fastest acceleration condition, and the rate of change of the engine's fastest deceleration condition.

[0057] For example, for the first preset operating condition, before step 110, the method may include:

[0058] A finite element model corresponding to the engine under test is created using finite element analysis tools;

[0059] The finite element analysis tool is used to generate a curve showing the change of contact stress of the camshaft in the finite element model as a function of engine speed, which is used as the relationship curve.

[0060] The finite element analysis tool can be flexibly selected based on the actual situation, such as CAE software. Engineers can use CAE software to create a finite element model corresponding to the engine under test, based on its structure and materials. The CAE software can then analyze the contact stress of the engine camshaft based on this finite element model and plot the curve of camshaft contact stress versus engine speed. This curve represents the relationship between camshaft contact stress and engine speed. This curve can be used to find the speed corresponding to the maximum contact stress, which is one of the control parameters in the first preset operating condition. The control parameters of the first preset operating condition may also include the torque corresponding to the speed.

[0061] For the second preset operating condition, before step 110, the method may further include:

[0062] Obtain the complete road spectrum of the engine under test, and divide the speed variation range of the engine under test into d segments, where d is an integer greater than 1;

[0063] Based on the complete road spectrum, the operating condition with the largest rate of change of each speed segment in segment d during the speed increase of the engine under test is determined as the acceleration sub-operating condition, and the acceleration sub-operating conditions corresponding to all speed segments in segment d are combined into an acceleration condition.

[0064] Based on the complete road spectrum, the operating condition with the largest rate of change of each speed segment in segment d during the speed reduction process of the engine under test is determined as the deceleration sub-operating condition, and the deceleration sub-operating conditions corresponding to all speed segments in segment d are combined into a deceleration operating condition.

[0065] Understandably, the complete road spectrum and speed variation range can be flexibly determined according to different engines under test. For example, a complete cycle of the engine's complete road spectrum (or vehicle road spectrum) can be 432 km, and the speed variation range can be from 1200 r / min to 5000 r / min. The speed variation range can be divided into d speed segments, where d can be flexibly determined according to actual conditions, for example, 4 segments.

[0066] In a complete road map, the engine speed changes over time. Within this road map, for each defined speed range, the operating condition with the fastest rate of change (i.e., the shortest change time) is selected as the sub-operating condition for that speed range. For example, if a speed range is 1200-2000 r / min, and assuming there are three curves in the road map covering the acceleration from 1200 r / min to 2000 r / min, the curve with the shortest acceleration time among the three is selected as the sub-operating condition for the 1200-2000 r / min speed range. All the sub-operating conditions corresponding to all speed ranges can then be combined to form the engine's fastest acceleration condition.

[0067] The selection method for the deceleration sub-condition is similar to that for the acceleration sub-condition, and will not be repeated here. The deceleration sub-conditions corresponding to all speed ranges can then be combined to form the fastest deceleration condition for the engine.

[0068] In step 110, before the engine is running, workers can use high-precision dimensional measuring tools to measure the dimensions of each component of the valve train to obtain the initial dimensions of each component as the first dataset.

[0069] The components to be measured may include, but are not limited to, one or more conventional parts selected from the following: camshaft, roller rocker arm, mechanical tappet, hydraulic tappet assembly, timing chain assembly, timing chain guide, timing chain moving guide, camshaft guide, crankshaft timing sprocket, tensioner, intake phaser assembly, exhaust phaser assembly, valve, valve guide, valve seat ring, valve spring, valve spring seat, valve spring base, and valve lock block.

[0070] In step 120, the components are assembled to obtain the assembly method of the engine under test, which can be flexibly determined according to the actual situation. That is, the engine assembly strategy can be flexibly selected according to the actual situation, which is a conventional implementation method.

[0071] As an optional implementation, between steps 120 and 130, the method may further include:

[0072] The engine under test is controlled to run for a third specified period of time in order to break in the engine under test.

[0073] The third specified duration can be flexibly set according to actual conditions, such as 1 hour. After the engine break-in is complete, the engine cylinder head cover can be removed to observe and photograph the engine camshaft wear. If there are no visible abnormalities in the engine camshaft wear, the break-in is normal, and subsequent testing procedures can continue. If there are visible abnormalities in the camshaft wear, such as bending or breakage, the break-in is abnormal, and the testing process needs to be terminated.

[0074] In this embodiment, various preset or specified values ​​can be flexibly determined according to actual conditions. For example, in step 130, the preset stress is a value characterizing a larger contact stress, which can be flexibly determined according to actual conditions, wherein the preset stress is less than the maximum contact stress. Step 130 may include:

[0075] Based on the pre-established relationship curve between camshaft contact stress and engine speed, the target speed n corresponding to the maximum contact stress in the relationship curve is selected;

[0076] The engine under test is controlled to run at the target speed n and a preset speed fluctuation range for a preset time, the preset time being the time corresponding to the completion of the first specified distance in the simulated vehicle road test.

[0077] The preset speed fluctuation range can be flexibly determined according to actual conditions. The torque corresponding to the target speed is the target torque of the engine during operation, which can be denoted as tq. For example, if the target speed n is 1200 r / min, the preset speed fluctuation range can be ±100 r / min. That is, the engine under test can run at 1200 ± 100 r / min for a preset duration. The preset duration and the first specified distance can be flexibly determined according to actual conditions. For example, the first specified distance can be 40,000 kilometers, and the preset duration can be 120 hours. Among them, the commonly used torque of 1200 r / min for a 1.5L engine can be 20 N·m.

[0078] In this embodiment, step 140 may include:

[0079] The engine under test is controlled to operate cyclically under the acceleration condition and the deceleration condition.

[0080] Controlling the engine under test to operate cyclically in the acceleration condition and the deceleration condition may include:

[0081] The engine under test is controlled to operate cyclically under the acceleration condition and the deceleration condition. During the cyclic operation, when the engine speed is at the maximum speed or the minimum speed, the maximum speed or the minimum speed is maintained for a first specified duration. When the current number of cycles is an integer multiple of M, when the engine under test has completed the current number of cycles, the engine under test is controlled to operate at the maximum speed for a second specified duration, where the second specified duration is longer than the first specified duration, and M is an integer greater than 1.

[0082] The first specified duration, the second specified duration, and M can all be flexibly set according to actual conditions. For example, the first specified duration can be 1 minute to allow the engine speed to reach a stable state after reaching its maximum or minimum speed. The second specified duration can be 10 minutes, and M can be 3. That is, under the second preset operating condition, after every 3 cycles of rapid engine acceleration and deceleration, the engine is kept running at its maximum speed, such as 5000 r / min, for 10 minutes to ensure that the engine remains at a high temperature throughout the second preset operating condition. The engine stops running after the specified number of acceleration and deceleration cycles. The specified number of cycles corresponds to the number of accelerations and decelerations for the first specified distance (e.g., 40,000 km) of the simulated vehicle road test.

[0083] In step 150, after the engine has run under the first preset operating condition and the second preset operating condition, the dimensions of the components corresponding to the valve train are measured again, so as to obtain the various dimensional data of the engine components after wear, which can be used as the second dataset.

[0084] In this embodiment, step 160 may include:

[0085] The wear value of each component in the valve train is obtained based on the data in the first dataset and the second dataset.

[0086] The test results of the valve train are obtained based on the wear value of each component.

[0087] In this embodiment, the method may further include:

[0088] When the wear value of any component exceeds the corresponding preset threshold, the control alarm module issues an alarm prompt indicating abnormal wear of the component.

[0089] The preset threshold can be flexibly determined according to the actual situation. The alarm module can be, but is not limited to, a buzzer, indicator light, display screen, etc., any module that can issue an alarm prompt.

[0090] To facilitate understanding of the method's implementation process, the following example illustrates the process using a 1.5L engine as an example. The detailed steps for determining the wear condition of the engine's valve train after an equivalent 40,000km road test using the method provided in this application are as follows:

[0091] S1: Determine the control parameters under operating condition a (i.e., the first preset operating condition) to verify the reliability of the valve train mechanism under high contact stress conditions.

[0092] Step S1 may include:

[0093] S101: Analyze the variation curve of camshaft contact stress with engine speed using CAE software tools. The analysis results are as follows: Figure 2 As shown;

[0094] S102: Analysis Figure 2 Below 4500 rpm, the camshaft contact stress increases as the engine speed decreases; above 4500 rpm, the camshaft contact stress increases as the engine speed increases. The 1.5L engine's speed range is 1200-5000 rpm, where 5000 rpm is the engine's rated speed and 1200 rpm is the engine's minimum stable operating speed. Figure 2 It was found that within the operating speed range of the engine, the contact stress of the camshaft is the greatest at a speed of 1200 r / min. Therefore, 1200 r / min is selected as the target speed n, and the commonly used torque at 1200 r / min is 20 N·m as the target torque tq.

[0095] S103: If the engine is used in a vehicle model and a complete road test cycle is 432km, and the cumulative running time of the simulated vehicle driving 432km within a speed range of 1200±100r / min is 1.3h, then the operating condition running time of stage a of the equivalent 40000km vehicle road test for the 1.5L engine can be calculated as t=1.3*(40000 / 432)=120h. This time is the preset time. The control parameters of operating condition a include the engine operating speed range of 1200±100r / min and the running time of 120h. As an example, the schematic diagram of the engine speed and time of the engine under test in operating condition a (first preset operating condition) can be shown as follows. Figure 6 As shown.

[0096] S2: Determine the control parameters for operating condition b (i.e., the second preset operating condition) to verify the reliability of the valve train under conditions of rapid changes in engine speed and torque.

[0097] Step S2 may include:

[0098] S201: Select a complete road cycle of 432km with the 1.5L engine equipped with a certain model. The speed range of the 1.5L engine is 1200-5000r / min. Select the minimum speed n1 = 1200r / min, the maximum speed nmax = 5000r / min, and the segment d = 4.

[0099] S202: Determine the engine speed variation range Δn = (5000-1200) / 4 = 950 r / min for the 1.5L engine, and for each speed range, extract the operating condition with the largest engine speed variation rate v from the 435km road spectrum data of a certain model equipped with the 1.5L engine. See [link / reference]. Figure 3a , Figure 3b , Figure 4a , Figure 4b ;

[0100] S203: For each speed range, select the operating condition with the largest rate of change v within each engine speed range during the engine speed increase process. See [link / reference] Figure 3a , Figure 3b By combining operating conditions corresponding to speeds increasing from 1200 to 5000 r / min, the fastest acceleration condition of the engine in this test was obtained. (See...) Figure 7 ;

[0101] S204: Select the operating condition with the largest rate of change v in each engine speed range during the engine speed reduction process. See [link / reference] Figure 4a , Figure 4b By combining operating conditions corresponding to speeds ranging from 5000 to 1200 r / min (from highest to lowest), the fastest deceleration condition for the engine in this test was determined. (See...) Figure 7 ;

[0102] S205: Count the number of times the engine speed change condition occurs in a complete cycle of 432km for a certain model with a 1.5L engine. If it is 10 times, the typical acceleration and deceleration times of the 1.5L engine in condition b can be calculated, y = 10 * (40000 / 432) ≈ 926 times.

[0103] S206: In operating condition b, the engine is set to run stably for 60 seconds after reaching 5000 r / min or 1200 r / min, so that the engine reaches a stable state;

[0104] S207: In the operating condition, after every 3 rapid acceleration and deceleration cycles, the engine is set to run continuously at 5000 r / min for 10 minutes to ensure that the engine is always at a high temperature throughout the entire b stage. The control parameters of operating condition b may include the torque corresponding to the fastest acceleration condition and the fastest deceleration condition, the number of cycles, etc.

[0105] As an example, in the entire operating condition b phase, the operating condition of a certain 1.5L engine is defined as follows, and the operating condition diagram is shown below. Figure 7 :

[0106] Operating condition 1: The engine runs to 1200 r / min and 20 N·m in 6 seconds and continues to run for 60 seconds.

[0107] Operating condition 2: The engine reaches 2150 r / min and 80 N·m in 2 seconds.

[0108] Operating condition 3: The engine reaches 3100 r / min and 100 N·m in 1 second.

[0109] Operating condition 4: The engine runs to 4050 r / min at full load in 3 seconds.

[0110] Operating condition 5: The engine reaches 5000 r / min in 1 second, operates at full throttle, and continues to run for 60 seconds.

[0111] Operating Condition 6: The engine reaches 4050 r / min in 1 second under no load.

[0112] Operating condition 7: The engine reaches 3100 r / min in 1 second under no load.

[0113] Operating condition 8: The engine reaches 2150 r / min in 1 second under no load.

[0114] Operating condition 9: The engine runs to 1200 r / min and 20 N·m in 6 seconds and continues to run for 60 seconds.

[0115] Operating condition 10: The engine runs to 2150 r / min and 80 N·m in 2 seconds.

[0116] Operating condition 11: The engine reaches 3100 r / min and 100 N·m in 1 second.

[0117] Operating condition 12: The engine runs to 4050 r / min in 3 seconds at full load.

[0118] Operating condition 13: The engine reaches 5000 r / min in 1 second, operates at full throttle, and continues to run for 60 seconds.

[0119] Operating condition 14: The engine reaches 4050 r / min in 1 second under no load.

[0120] Operating condition 15: The engine runs to 3100r / min in 1 second without load.

[0121] Operating condition 16: The engine reaches 2150 r / min in 1 second under no load.

[0122] Operating condition 17: Repeating operating conditions 9 to 16.

[0123] Operating conditions one through seventeen comprise three acceleration and deceleration conditions. In condition b, the test needs to be repeated a total of 926 / 3 ≈ 309 times, from condition one to condition seventeen. The total runtime for condition b is approximately 8 days. As an example, a schematic diagram of the engine speed versus time in condition b (the second preset condition) can be shown as follows: Figure 7 As shown.

[0124] S3: Perform precise dimensional measurements on the valve train components of the engine to be verified. These components include, but are not limited to, camshafts, roller rocker arms, mechanical tappets, hydraulic tappet assemblies, timing chain assemblies, timing chain guides, timing chain moving guides, camshaft guides, crankshaft timing sprockets, tensioners, intake phaser assemblies, exhaust phaser assemblies, valves, valve guides, valve seats, valve springs, valve spring seats, valve spring bases, and valve lock blocks.

[0125] S4: Perform engine assembly or valve train replacement in accordance with the engine assembly operation manual.

[0126] S5: Install the test engine on the engine test bench and ensure that the test engine and test bench are working properly. In principle, the engine should be operated under the following conditions.

[0127] a) Engine coolant outlet temperature: within ±6℃ of the fully open temperature of the mechanical thermostat or within 95±6℃ of the electronic thermostat or within the design range.

[0128] b) Engine oil temperature: Not higher than the engine's maximum permissible engine oil temperature;

[0129] c) Other test conditions shall be controlled in accordance with existing relevant regulations.

[0130] S6: Perform a 1-hour break-in period on the engine. See the break-in performance curve below. Figure 5 .

[0131] S7: After the break-in period is complete, remove the engine cylinder head cover to observe and take photos to record the wear of the engine camshaft.

[0132] S8: Run the test condition a determined in S1 for a total of 120 hours.

[0133] S9: Run the test condition b determined in S2, for a total of 309 cycles of the above conditions one through seventeen.

[0134] S10: The test is completed. The engine is disassembled and inspected to observe the appearance of the engine valve train.

[0135] S11: Perform precise dimensional measurements on valve train components, including but not limited to camshafts, roller rocker arms, mechanical tappets, hydraulic tappet assemblies, timing chain assemblies, timing chain guides, timing chain moving guides, camshaft guides, crankshaft timing sprockets, tensioners, intake phaser assemblies, exhaust phaser assemblies, valves, valve guides, valve seats, valve springs, valve spring seats, valve spring bases, and valve lock blocks.

[0136] S12: Evaluate the engine timing system. The evaluation criteria may be: there shall be no obvious abnormal wear or overheating marks on the contact surfaces of the valve train components. After precise retesting of the valve train components, the wear amount shall not exceed the evaluation criteria requirements of the corresponding components.

[0137] Based on the above design, and considering the typical operating conditions of the engine during vehicle road testing, combined with the risk points of the main components of the valve train, a test verification scheme equivalent to 40,000 km of vehicle road testing can be achieved by utilizing time equivalence (120 hours for condition a, equivalent to 5 days) and number of equivalent cycles (926 accelerations and decelerations for condition b, approximately 8 days). Using the method provided in this embodiment, the engine is tested under relatively extreme conditions for 13 days, which is equivalent to 2 months of existing vehicle road testing (existing engine bench durability tests mainly consist of full-speed full-load, alternating load, and thermal shock tests, each lasting approximately 20 days, totaling 2 months) for valve train wear verification. Therefore, this method effectively improves verification efficiency, shortens the verification cycle, and saves on the cost of valve train wear detection.

[0138] Based on the above description of the embodiments, those skilled in the art can clearly understand that this application can be implemented by hardware or by using software plus necessary general-purpose hardware platforms. Based on this understanding, the technical solution of this application can be embodied in the form of a software product. This software product can be stored in a non-volatile storage medium (such as CD-ROM, USB flash drive, mobile hard drive, etc.) and includes several instructions to cause a computer device (such as a personal computer, server, or network device, etc.) to execute the methods described in the various implementation scenarios of this application.

[0139] In the embodiments provided in this application, it should be understood that the disclosed systems and methods can also be implemented in other ways. The system and method embodiments described above are merely illustrative. For example, the flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, program segment, or part of code, which includes one or more executable instructions for implementing a specified logical function. It should also be noted that each block in a block diagram and / or flowchart, and combinations of blocks in block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions. Furthermore, the functional modules in the various embodiments of this application can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0140] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for testing an engine valve train, characterized in that, include: The dimensions of the components corresponding to the unassembled engine valve train are measured to obtain the first dataset of the components; According to the engine assembly strategy, the unassembled parts are assembled to obtain the engine to be tested; The engine under test is controlled to operate under a first preset operating condition, wherein, under the first preset operating condition, the contact stress of the camshaft of the engine under test exceeds a preset stress; The engine under test is controlled to operate under a second preset operating condition, wherein the speed of the engine under test changes according to a preset control strategy under the second preset operating condition. When the engine under test completes the first preset operating condition and the second preset operating condition, the engine under test is disassembled, and the dimensions of the components corresponding to the disassembled valve train are measured to obtain the second dataset of the components. Based on the first dataset and the second dataset, detection results characterizing the wear of the valve train mechanism are obtained; Controlling the engine under test to operate under a first preset condition includes: Based on the pre-established relationship curve between the contact stress of the camshaft and the engine speed to be tested, the target speed n corresponding to the maximum contact stress in the relationship curve is selected; The engine under test is controlled to run at the target speed n and a preset speed fluctuation range for a preset duration, where the preset duration is the time corresponding to the completion of the first specified distance in the simulated vehicle road test. Before measuring the dimensions of the components corresponding to the unassembled engine valve train, the following steps are also included: Obtain the complete road spectrum of the engine under test, and divide the speed variation range of the engine under test into d segments, where d is an integer greater than 1; Based on the complete road spectrum, the operating condition with the largest rate of change of each speed segment in segment d during the speed increase of the engine under test is determined as the acceleration sub-operating condition, and the acceleration sub-operating conditions corresponding to all speed segments in segment d are combined into an acceleration condition. Based on the complete road spectrum, the operating condition with the largest rate of change of each speed segment in segment d during the speed reduction of the engine under test is determined as the speed reduction sub-operating condition, and the speed reduction sub-operating conditions corresponding to all speed segments in segment d are combined into a speed reduction condition. Controlling the engine under test to operate under a second preset condition includes: The engine under test is controlled to operate cyclically under the acceleration condition and the deceleration condition.

2. The method according to claim 1, characterized in that, Before measuring the dimensions of the components corresponding to the unassembled engine valve train, the following steps are also included: A finite element model corresponding to the engine under test is created using finite element analysis tools; The finite element analysis tool is used to generate a curve showing the change of contact stress of the camshaft in the finite element model with the engine speed under test, which is used as the relationship curve.

3. The method according to claim 1, characterized in that, Controlling the engine under test to operate cyclically under the acceleration condition and the deceleration condition includes: The engine under test is controlled to operate cyclically under the acceleration condition and the deceleration condition. During the cyclic operation, when the engine speed is at its maximum or minimum speed, the engine is maintained at its maximum or minimum speed for a first specified duration. When the current number of cycles is an integer multiple of M, when the engine under test has completed the current number of cycles, the engine is controlled to operate at its maximum speed for a second specified duration, where the second specified duration is longer than the first specified duration, and M is an integer greater than 1. The operation stops when the specified number of cycles is reached.

4. The method according to claim 1, characterized in that, Before controlling the engine under test to operate under a first preset condition, the method further includes: The engine under test is controlled to run for a third specified period of time in order to break in the engine under test.

5. The method according to claim 1, characterized in that, Based on the first dataset and the second dataset, detection results characterizing the wear of the valve train mechanism are obtained, including: The wear value of each component in the valve train is obtained based on the data in the first dataset and the second dataset. The test results of the valve train are obtained based on the wear value of each component.

6. The method according to claim 4, characterized in that, Also includes: When the wear value of any component exceeds the corresponding preset threshold, the control alarm module issues an alarm prompt indicating abnormal wear of the component.

7. The method according to any one of claims 1-6, characterized in that, The components include at least one of the following: camshaft, roller rocker arm, mechanical tappet, hydraulic tappet assembly, timing chain assembly, timing chain fixed rail, timing chain moving rail, camshaft guide rail, crankshaft timing sprocket, tensioner, intake phaser assembly, exhaust phaser assembly, valve, valve guide, valve seat ring, valve spring, valve spring seat, valve spring base, and valve lock block.

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