A diesel engine reliability verification method and acceleration coefficient calculation method

Abstract

The present invention discloses a method for calculating the acceleration coefficient of a diesel engine, comprising the following steps: S1: determining product reliability indicators through market research and benchmarking against competing products; S2: collecting actual operating conditions and usage scenarios of typical users, and extracting typical common operating conditions; S3: analyzing engine parameters under typical user operating conditions, comparing the engine's normal operating environment stress with the engine's stress design index limit, and evaluating the design margin; S4: within the stress design index limit, selecting multiple groups of stresses exceeding the engine's normal operating environment stress by a ratio greater than the typical user operating condition stress design index limit to conduct bench reliability testing; S5: establishing an isopower or isofuel consumption model based on the experimental data recorded in step 4, and calculating the engine's acceleration coefficient. This invention has the advantages of shortening product development time, saving development costs, and improving product competitiveness through accelerated testing technology.

Description

Technical Field

[0001] The present invention relates to the technical field of engine testing, and in particular to a diesel engine reliability verification method and an acceleration coefficient calculation method. Background Art

[0002] Engine reliability test conditions on a test bench differ from actual vehicle operating conditions. With the advancement of technology, mechanization is becoming increasingly advanced across various fields, leading to higher quality requirements for corresponding products. Many product lifespans are measured in years or hours, with the B10 (lifespan) durability indicator for non-road engines typically ranging from 15,000 to 25,000 hours. Traditional reliability methods, which simulate actual vehicle operating conditions on a test bench, result in long verification cycles and high test bench costs, making them inadequate for rapidly changing market demands.

[0003] Currently, the duration of engine durability verification for world-class companies reaches half the B10 lifespan, while that for domestic companies generally does not exceed one-third of the B10 lifespan. The specific verification time is determined by each company based on its own capabilities and needs. Therefore, engine durability verification still takes a long time, impacting product development cycles.

[0004] According to stress-life theory and the SN curve, experiments have shown that stress affects fatigue life: high cycle stress means low life, while low cycle stress means high life. S is stress, and N is life. The formula is as follows:

[0005]

[0006] S: stress amplitude;

[0007] N: Number of stress cycles to failure (lifespan), β and α are material coefficients.

[0008] The disclosure of the above background technology content is only used to assist in understanding the concept and technical solution of the present invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above content has been disclosed on the filing date of this patent application, the above background technology should not be used to evaluate the novelty and creativity of this application. Summary of the Invention

[0009] The present invention aims to provide a diesel engine reliability verification method and an acceleration coefficient calculation method using accelerated test technology to shorten product development time, save development costs, and improve product competitiveness.

[0010] To this end, the present invention proposes a diesel engine reliability verification method and an acceleration coefficient calculation method.

[0011] Preferably, the present invention may also have the following technical features:

[0012] A method for calculating an acceleration coefficient of a diesel engine comprises the following steps:

[0013] S1: Determine product reliability indicators through market research and competitive product benchmarking;

[0014] S2: Collect typical users' actual usage conditions and usage scenarios, and extract typical common usage conditions;

[0015] S3: Analyze engine parameters under typical user operating conditions, compare the engine's normal operating environment stress with the engine stress design index limit, and evaluate the design margin;

[0016] S4: Within the stress design index limit, select multiple groups of stresses exceeding the normal operating environment stress of the engine for bench reliability testing according to the ratio greater than the typical user operating condition stress design index limit;

[0017] S5: Establish an equal power or equal fuel consumption model based on the experimental data recorded in step 4, calculate the hourly cycle power or hourly cycle fuel consumption exceeding the normal working environment stress of the engine and the hourly cycle power or hourly cycle fuel consumption under the normal working environment stress of the engine, compare the hourly cycle power or hourly cycle fuel consumption corresponding to the two sets of data, and the obtained ratio is the engine acceleration factor under the working condition exceeding the normal working environment stress of the engine.

[0018] Furthermore, in step S3, the engine parameters include speed, torque, water temperature, oil temperature, air temperature, and pressure.

[0019] Furthermore, in step S3, by analyzing the actual use conditions of typical users, the proportion of the engine hourly average stress of the typical user's actual use conditions to the engine stress design index limit in the bench reliability test conditions is determined.

[0020] Furthermore, based on the speed and stress of the diesel engine tractor during rotary tillage operations in the field, the distribution of the engine speed and stress is obtained, and then the ratio of the hourly average stress of the diesel engine tractor to the engine stress design index limit is determined.

[0021] Furthermore, it was determined that the hourly average stress of the diesel engine tractor was equivalent to 29% of the engine stress design index limit.

[0022] Furthermore, in step S4, the selected stress range is 50% to 100% of the engine stress design index limit, and the selected stress value range exceeds the normal working environment stress of the engine.

[0023] Furthermore, 50%, 75%, 90% and 100% of the engine stress design index limits were selected for bench reliability tests, and the test data of each group of stresses were recorded. The recorded test data included hourly cycle power and hourly cycle fuel consumption.

[0024] Further, in step S5, the calculated acceleration coefficient = the hourly cycle power exceeding the normal working environment stress of the engine / the hourly cycle power of the normal working environment stress of the engine, or the calculated acceleration coefficient = the hourly cycle fuel consumption exceeding the normal working environment stress of the engine / the hourly cycle fuel consumption of the normal working environment stress of the engine.

[0025] Furthermore, the value of the acceleration coefficient is 1.5-4.

[0026] A method for accelerating engine bench reliability testing,

[0027] Obtaining a target acceleration coefficient according to the engine acceleration coefficient calculation method of claim 1;

[0028] According to the determined acceleration coefficient value, the corresponding test bench stress design index limit ratio is set;

[0029] Start bench reliability testing. The time required for bench verification = conventional engine durability verification time / acceleration factor.

[0030] The beneficial effects of the present invention compared to the prior art include: when testing under increased load, the test time t1 in this case is reduced by a multiple of the normal test time t2 according to the value of the acceleration factor n. That is, when testing under increased load, the acceleration factor corresponding to the load is 3.3, indicating that the normal test time is 20,000 hours, while the increased load test time is 20,000 / 3.3 hours, which can achieve the same test effect as a normal test of 20,000 hours. Accelerated testing technology shortens product development time, saves development costs, and quickly brings it to market, meeting customer needs, and thus improving product competitiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a comparison diagram of the acceleration effect of the present invention.

[0032] Figure 2 This is a model diagram of equal power or equal fuel consumption under one of the stress conditions of the present invention.

[0033] Figure 3 is based on Figure 2 The calculated acceleration factor value. DETAILED DESCRIPTION

[0034] The present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be emphasized that the following description is merely illustrative and is not intended to limit the scope of the present invention and its application.

[0035] Non-limiting and non-exclusive embodiments will be described with reference to the following figures, wherein like reference numerals refer to like parts unless otherwise specifically specified.

[0036] like Figures 1 to 3 The diesel engine acceleration factor calculation method shown in the figure tests the engine under stress beyond the normal operating environment. By increasing the stress, the normal degradation process is accelerated. The purpose is to shorten the normal failure process without changing the physical characteristics of the failure, thereby reducing R&D costs.

[0037] The acceleration coefficient calculation method comprises the following steps:

[0038] S1: Determine product reliability index B10 through market research and competitive product benchmarking;

[0039] S2: Collect typical users' actual usage conditions and usage scenarios, and extract typical common usage conditions;

[0040] S3: Analyze engine parameters under typical user operating conditions, compare the engine's normal operating environment stress with the engine stress design index limits, and evaluate design margins; the engine parameters include speed, torque, water temperature, oil temperature, air temperature, and pressure;

[0041] In step S3, the typical user's actual operating conditions are analyzed to determine the percentage of the hourly average engine stress under these conditions relative to the engine stress design limit in the bench reliability test conditions. Taking a certain type of tractor as an example, the analysis of the typical user's actual operating conditions determined that the hourly average stress under these conditions was equivalent to 29% of the engine stress design limit. The normal operating environment stress of the engine of the tractor in this embodiment is determined to be 29% of the engine stress design limit.

[0042] Specifically, analysis of the speed and stress of the diesel engine tractor during rotary tillage operations revealed a wide range of engine speeds, with a high proportion of low and high speeds and a relatively low proportion of intermediate speeds. Furthermore, the engine stress (load) distribution showed a high proportion of low loads and a low proportion of medium and high loads. Furthermore, the hourly average stress of the diesel engine tractor was determined to be equivalent to 29% of the engine stress design limit.

[0043] S4: Within the stress design index limit, select multiple sets of stresses for bench reliability testing according to the stress design index limit ratio; select multiple sets of stresses that exceed the normal operating environment stress of the engine.

[0044] In step S4, the selected stress range is 50% to 100% of the engine stress design index limit of the tractor to be bench-tested. This stress value range exceeds the normal operating environment stress of the tractor of this embodiment. The range of stress selected for the bench reliability test condition exceeds the normal operating environment stress of the tractor's engine. Specifically, bench reliability tests are performed at 50%, 75%, 90%, and 100% of the engine stress design index limit, and test data for each stress group is recorded. The recorded test data includes hourly cycle power and hourly cycle fuel consumption. A bench reliability test is also performed at 29% of the engine stress design index limit, and the relevant data is recorded.

[0045] S5: Establish an equal power or equal fuel consumption model based on the experimental data recorded in step 4, calculate the hourly cycle power or hourly cycle fuel consumption that exceeds the normal working environment stress of the engine and the hourly cycle power or hourly cycle fuel consumption of the normal working environment stress of the engine, and compare the hourly cycle power or hourly cycle fuel consumption corresponding to the two sets of data. The ratio obtained is the engine acceleration coefficient under the working condition that exceeds the normal working environment stress of the engine. If the acceleration coefficient is greater than 1, the time required for bench verification can be shortened.

[0046] Generally, the calculated acceleration factor = hourly cycle power exceeding the normal operating environment stress of the engine / hourly cycle power of the normal operating environment stress of the engine, or the calculated acceleration factor = hourly cycle fuel consumption exceeding the normal operating environment stress of the engine / hourly cycle fuel consumption of the normal operating environment stress of the engine. Preferably, the value of the acceleration factor is 1.5-4.

[0047] Reference Figures 1 to 3 A method for accelerating engine bench reliability testing uses 1 / 2 or 1 / 3 of the engine's B10 lifespan (time) as the conventional engine durability verification time. A target acceleration factor is obtained using the aforementioned acceleration factor calculation method, with the acceleration factor being between 1.5 and 4. A corresponding bench stress design index limit ratio is set based on the determined acceleration factor value. The bench reliability test is initiated, with the bench verification time calculated as the conventional engine durability verification time divided by the acceleration factor. Thus, during the bench reliability test, the engine is subjected to stresses exceeding the normal operating environment, accelerating the normal degradation process by increasing the stress. The time required for bench verification is then calculated, based on the acceleration factor value n, to be reduced by a multiple of the conventional engine durability verification time.

[0048] In reference Figure 1The hourly average stress of a diesel engine tractor, corresponding to 29% of the engine stress design limit, is used as the standard bench reliability test, i.e., the comparative example. This comparative example indicates that under operating conditions at 29% of the engine stress design limit, the bench verification duration is 1 / 2 or 1 / 3 of the standard verification duration, i.e., the B10 life of 20,000 hours. In this comparative example, 1 / 2 of the B10 life is used as the standard verification duration, and the bench verification duration t3 is determined to be 10,000 hours.

[0049] Carry out Examples 1 to 4 under working conditions exceeding the normal working environment stress of the tractor of this embodiment, calculate the acceleration coefficient corresponding to the stress design index limit ratio, and then calculate the bench verification time t4 after reducing the times by the acceleration coefficient value. Figure 1 It can be seen that the conventional bench verification time is 10,000 hours. After acceleration using the method of the present invention, the bench verification time is reduced by a multiple of the acceleration coefficient. The required verification time is reduced by 4 times compared with the conventional bench verification time. The accelerated test technology shortens product development time, saves development costs, quickly puts it on the market, meets customer needs, and thus improves product competitiveness.

[0050] Those skilled in the art will recognize that numerous variations to the foregoing description are possible, and that the examples and figures are intended only to describe one or more specific implementations.

[0051] Although what is considered to be exemplary embodiments of the present invention has been described and illustrated, it will be understood by those skilled in the art that various changes and substitutions may be made thereto without departing from the spirit of the present invention. In addition, many modifications may be made to adapt a particular situation to the teachings of the present invention without departing from the central concept of the invention described herein. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but rather encompasses all embodiments and their equivalents falling within the scope of the present invention.

Claims

1. A method for calculating the acceleration coefficient of a diesel engine, characterized by: The steps include: S1: Determine product reliability indicators through market research and competitive product benchmarking; S2: Collect typical users' actual usage conditions and usage scenarios, and extract typical common usage conditions; S3: Analyze engine parameters under typical user operating conditions, compare the engine's normal operating environment stress with the engine stress design index limit, and evaluate the design margin; By analyzing the actual operating conditions of typical users, determine the proportion of the engine hourly average stress under the actual operating conditions of typical users to the engine stress design index limit in the bench reliability test conditions; Based on the speed and stress of a diesel engine tractor during rotary tillage operations in the field, the distribution of engine speed and stress is obtained, and then the ratio of the diesel engine tractor's hourly average stress to the engine stress design index limit is determined; S4: Within the stress design index limit, select multiple groups of stress exceeding the normal operating environment stress of the engine for bench reliability testing according to the ratio greater than the typical user operating condition stress design index limit; S5: Establishing an equal power or equal fuel consumption model based on the experimental data recorded in step 4, calculating the hourly cycle power or hourly cycle fuel consumption exceeding the normal working environment stress of the engine and the hourly cycle power or hourly cycle fuel consumption under the normal working environment stress of the engine, comparing the hourly cycle power or hourly cycle fuel consumption corresponding to the two sets of data, and the obtained ratio is the engine acceleration factor under the working condition exceeding the normal working environment stress of the engine; The value of the acceleration coefficient is 1.5-4.

2. A diesel engine acceleration coefficient calculation method according to claim 1, characterized in that: In step S3, the engine parameters include speed, torque, water temperature, oil temperature, air temperature, and pressure.

3. The method for calculating the acceleration coefficient of a diesel engine according to claim 1, wherein: The hourly average stress of the diesel engine tractor was determined to be equivalent to 29% of the engine stress design index limit.

4. A method for calculating the acceleration coefficient of a diesel engine according to claim 1, characterized in that: In step S4, the selected stress range is 50% to 100% of the engine stress design index limit, and the selected stress value range exceeds the normal working environment stress of the engine.

5. A method for calculating the acceleration coefficient of a diesel engine according to claim 4, characterized in that: 50%, 75%, 90% and 100% of the engine stress design index limits were selected for bench reliability tests, and the test data of each group of stresses were recorded. The recorded test data included hourly cycle power and hourly cycle fuel consumption.

6. A method for calculating the acceleration coefficient of a diesel engine as claimed in claim 1, characterized in that: In step S5, the calculated acceleration coefficient = hourly cycle power exceeding the normal working environment stress of the engine / hourly cycle power of the normal working environment stress of the engine, or the calculated acceleration coefficient = hourly cycle fuel consumption exceeding the normal working environment stress of the engine / hourly cycle fuel consumption of the normal working environment stress of the engine.

7. A method for accelerating engine bench reliability testing, characterized by: Obtaining a target acceleration coefficient according to the engine acceleration coefficient calculation method of claim 1; According to the determined acceleration coefficient value, the corresponding test bench stress design index limit ratio is set; Start bench reliability testing. The time required for bench verification = conventional engine durability verification time / acceleration factor.

Images