Method for establishing, measuring and evaluating engine oil pressure based on abrasion

Abstract

The invention discloses a method for establishing measurement and evaluation of engine oil pressure based on abrasion, belongs to the technical field of engine abrasion evaluation, and solves the technical problem that an existing abrasion measurement and evaluation method is large in deviation. The method comprises the following steps of 1, measuring the rotating speed of an engine in the starting process, and accumulating the number of turns of a crankshaft before oil pressure is established; step 2, converting into a sliding distance of a crankshaft bearing or a piston according to the number of turns of the crankshaft; 3, according to the sliding distance, calculating abrasion in boundary lubrication and dry friction states through an abrasion model; and 4, evaluating the rationality of the engine starting pressure buildup according to the wear. Abrasion is calculated according to the sliding distance of the crankshaft bearing or the piston, the influence of starting transient performance can be reduced, the difference from the actual abrasion condition is small, and starting abrasion can be measured and evaluated more visually and quantitatively.

Description

Technical Field

[0001] This invention relates to the field of engine wear evaluation technology, and more specifically, to a method for measuring and evaluating wear-based oil pressure. Background Technology

[0002] After the engine stops, the lubricating oil gradually flows back to the oil pan. At the moment of starting, the moving parts (such as cylinder liners, pistons, crankshafts, crankshaft bearings, connecting rod bearings, etc.) are in a state of boundary lubrication or even dry friction until the oil pump rebuilds the oil pressure and the moving parts establish an oil film. It usually takes several seconds to more than ten seconds to build up the oil pressure.

[0003] Current technology evaluates the reasonableness of wear by measuring oil pressure build-up time. However, this measurement method is affected by the transient performance during startup and may deviate from the expected value. For example, increasing the fuel injection volume during startup can quickly accelerate the engine, and the oil pump can also quickly build up oil pressure; or there may be differences in the starting performance of different engine models. If the current build-up time is used for evaluation, the actual wear situation will vary considerably. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the above-mentioned shortcomings of the prior art. The purpose of the present invention is to provide a method for measuring and evaluating oil pressure based on wear, which can directly calculate wear to evaluate the rationality of starting pressure build-up.

[0005] The technical solution of this invention is: a method for establishing, measuring, and evaluating oil pressure based on wear, comprising the following steps:

[0006] Step 1. Measure the engine speed during the starting process and accumulate the number of crankshaft revolutions before the oil pressure is established;

[0007] Step 2. Convert the crankshaft revolution count into the sliding distance of the crankshaft bearing or piston;

[0008] Step 3. Calculate the wear under boundary lubrication and dry friction conditions using the wear model based on the sliding distance;

[0009] Step 4. Evaluate the rationality of the engine start-up pressure based on the wear.

[0010] As a further improvement, the formula for calculating the sliding distance of the crankshaft bearing is: s = c * n; where s is the sliding distance, c is the circumference of the main journal of the crankshaft, and n is the number of crankshaft revolutions.

[0011] Furthermore, the formula for converting the piston's sliding distance is: s = h * n * 2; where h is the piston stroke.

[0012] Furthermore, the wear includes starting wear, calculated as follows:

[0013] W1=k*Fn*s / H

[0014] Where W1 is the starting wear, k is the dimensionless wear coefficient, Fn is the normal load, s is the sliding distance, and H is the material hardness.

[0015] Furthermore, the wear also includes long-term cumulative wear, calculated as follows:

[0016] W2∑(k c *F i *V i *t i *e -βTi )

[0017] Where W2 represents long-term cumulative wear, k c F represents the cold start wear coefficient. i V i Let t be the normal load and sliding velocity at the i-th start-up. i Where β is the lubrication delay time, Ti is the start-up temperature, and β is the temperature sensitivity coefficient.

[0018] Furthermore, when the wear exceeds a preset value, it indicates that the start-up pressure build-up time is too long, and auxiliary pressure build-up measures are taken to reduce the start-up pressure build-up time.

[0019] Furthermore, the auxiliary pressure-building measures are as follows: an electric oil pump is added to the lubrication circuit, and the electric oil pump is connected in parallel with the engine oil pump; when the vehicle is started, the electric oil pump is started to supply oil; when the starting pressure is reached, the electric oil pump is turned off.

[0020] Furthermore, when the long-term cumulative wear reaches a set value, the user is reminded to perform maintenance; after maintenance, the long-term cumulative wear is reset to zero and recalculated.

[0021] Furthermore, the engine oil quality parameters are detected and saved for use in correcting the dimensionless wear coefficient k or cold start wear coefficient kc during the next engine start.

[0022] Furthermore, historical starting wear data is saved, and a starting wear trend curve is plotted. The working life of the oil pump is determined based on the starting wear trend curve.

[0023] Beneficial effects

[0024] Compared with the prior art, the advantages of this invention are as follows:

[0025] This invention calculates wear based on the sliding distance of crankshaft bearings or pistons, which can reduce the impact of transient starting performance, has little difference from the actual wear situation, and can more intuitively and quantitatively measure and evaluate starting wear. Attached Figure Description

[0026] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0027] The present invention will be further described below with reference to specific embodiments shown in the accompanying drawings.

[0028] See Figure 1 A wear-based method for measuring and evaluating engine oil pressure includes the following steps:

[0029] Step 1. Measure the engine speed during the starting process and accumulate the number of crankshaft revolutions before the oil pressure is established;

[0030] Step 2. Convert the crankshaft revolution count into the sliding distance of the crankshaft bearings or pistons;

[0031] Step 3. Calculate the wear under boundary lubrication and dry friction conditions using the wear model based on the sliding distance;

[0032] Step 4. Evaluate the rationality of engine start-up pressure based on wear.

[0033] Specifically, the formula for converting the sliding distance of the crankshaft bearing is: s = c * n; where s is the sliding distance, c is the circumference of the main journal of the crankshaft, and n is the number of crankshaft revolutions.

[0034] The formula for converting the piston's sliding distance is: s = h * n * 2; where h is the piston stroke.

[0035] Wear includes starting wear, calculated as follows:

[0036] W1=k*Fn*s / H

[0037] Where W1 is the starting wear, k is the dimensionless wear coefficient, Fn is the normal load, s is the sliding distance, and H is the material hardness.

[0038] Wear also includes long-term cumulative wear, calculated as follows:

[0039] W2∑(k c *F i *V i *t i *e -βTi )

[0040] Where W2 represents long-term cumulative wear, k c F represents the cold start wear coefficient. i V i Let t be the normal load and sliding velocity at the i-th start-up. i Where β is the lubrication delay time, Ti is the start-up temperature, and β is the temperature sensitivity coefficient.

[0041] When wear exceeds the preset value, it indicates that the start-up pressure build-up time is too long. Auxiliary pressure build-up measures are then implemented to reduce this time. These measures include: adding an electric oil pump to the lubrication circuit. This electric oil pump is connected in parallel with the engine oil pump (which is a mechanical pump that starts working when the engine starts). The output of the electric oil pump is equipped with a check valve to prevent oil backflow when the electric oil pump is not operating. The electric oil pump starts supplying oil when the vehicle is ignited; once the start-up pressure is reached, the electric oil pump is shut off.

[0042] When the accumulated wear reaches the set value, the user is reminded to perform maintenance; after maintenance, the accumulated wear will be reset to zero and recalculated.

[0043] The engine oil quality parameters are measured and saved for use in the next engine start-up to correct the dimensionless wear coefficient k or the cold start wear coefficient kc. Engine oil quality parameters include at least one of oil viscosity, oil density, and oil dielectric constant. Deterioration in these parameters reduces the oil's lubricating effect. Correction coefficients corresponding to these parameters are calibrated and compiled into a correction coefficient MAP table. During application, the corresponding correction coefficient is obtained from the MAP table based on the actual engine oil quality parameters. This correction coefficient is then used to adjust the dimensionless wear coefficient k or the cold start wear coefficient kc, ensuring the accuracy of the calculated wear coefficient.

[0044] In one embodiment, historical starting wear is saved and a starting wear trend curve is plotted. The working life of the oil pump is determined based on the starting wear trend curve. That is, the greater the starting wear, the longer the start-up pressure build-up time. The longer the start-up pressure build-up time, the worse the performance of the oil pump becomes. When the performance of the oil pump deteriorates to a certain extent, it means that the working life of the oil pump has been reached and it needs to be replaced or repaired.

[0045] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention, and these will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. A method for establishing, measuring, and evaluating wear-based oil pressure, characterized in that, Includes the following steps: Step 1. Measure the engine speed during the starting process and accumulate the number of crankshaft revolutions before the oil pressure is established; Step 2. Convert the crankshaft revolution count into the sliding distance of the crankshaft bearing or piston; Step 3. Calculate the wear under boundary lubrication and dry friction conditions using the wear model based on the sliding distance; Step 4. Evaluate the rationality of the engine start-up pressure based on the wear.

2. The method for establishing, measuring, and evaluating wear-based oil pressure according to claim 1, characterized in that, The formula for converting the sliding distance of the crankshaft bearing is: s = c * n; where s is the sliding distance, c is the circumference of the main journal of the crankshaft, and n is the number of crankshaft revolutions.

3. The method for establishing, measuring, and evaluating wear-based oil pressure according to claim 1, characterized in that, The formula for converting the piston's sliding distance is: s = h * n * 2; where h is the piston stroke.

4. The method for establishing, measuring, and evaluating wear-based oil pressure according to claim 1, characterized in that, The wear includes starting wear, calculated as follows: W1=k*Fn*s / H Where W1 is the starting wear, k is the dimensionless wear coefficient, Fn is the normal load, s is the sliding distance, and H is the material hardness.

5. The method for establishing, measuring, and evaluating wear-based oil pressure according to claim 4, characterized in that, The wear also includes long-term cumulative wear, calculated as follows: W2∑(k c *F i *V i *t i *e -βTi ) Where W2 represents long-term cumulative wear, k c F represents the cold start wear coefficient. i V i Let t be the normal load and sliding velocity at the i-th start-up. i Where β is the lubrication delay time, Ti is the start-up temperature, and β is the temperature sensitivity coefficient.

6. A method for establishing, measuring, and evaluating wear-based oil pressure according to any one of claims 1-5, characterized in that, When the wear exceeds a preset value, it indicates that the start-up pressure build-up time is too long, and auxiliary pressure build-up measures are taken to reduce the start-up pressure build-up time.

7. The method for establishing, measuring, and evaluating wear-based oil pressure according to claim 6, characterized in that, The auxiliary pressure-building measures are as follows: an electric oil pump is added to the lubrication circuit, and the electric oil pump is connected in parallel with the engine oil pump; when the vehicle is started, the electric oil pump is started to supply oil; when the starting pressure is reached, the electric oil pump is turned off.

8. The method for establishing, measuring, and evaluating wear-based oil pressure according to claim 5, characterized in that, When the long-term cumulative wear reaches the set value, the user is reminded to perform maintenance; after maintenance, the long-term cumulative wear is reset to zero and recalculated.

9. The method for establishing, measuring, and evaluating wear-based oil pressure according to claim 5, characterized in that, The engine oil quality parameters are detected and saved for use in correcting the dimensionless wear coefficient k or cold start wear coefficient kc during the next engine start.

10. The method for establishing, measuring, and evaluating wear-based oil pressure according to claim 4, characterized in that, Save historical starting wear data and plot a starting wear trend curve. Determine the working life of the oil pump based on the starting wear trend curve.

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