CN111894781A - Test method for judging maximum lift of needle valve - Google Patents
Test method for judging maximum lift of needle valve Download PDFInfo
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- CN111894781A CN111894781A CN202010613461.1A CN202010613461A CN111894781A CN 111894781 A CN111894781 A CN 111894781A CN 202010613461 A CN202010613461 A CN 202010613461A CN 111894781 A CN111894781 A CN 111894781A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M65/00—Testing fuel-injection apparatus, e.g. testing injection timing ; Cleaning of fuel-injection apparatus
- F02M65/005—Measuring or detecting injection-valve lift, e.g. to determine injection timing
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Abstract
The invention provides a test method for judging the maximum lift of a needle valve, which comprises the following steps: A. for common rail injector at different pressures p and different pulse widths tcLower cycle fuel injection quantity v, fuel injection duration t and fuel injection opening delay toAnd standard deviation sigma of multi-cycle fuel injection quantityvCarrying out a first round of test; B. shortening the pulse width tcInterval, cyclic fuel injection quantity v and pulse width tcThe relationship curve has an inflection point, and the multi-cycle fuel injection standard deviation sigma is combinedvThe maximum needle valve lift L is judged according to the variation trend ofmaxCorresponding pulse width tcThe interval range of (a); C. the common rail oil injector is disassembled and inspected, the maximum needle valve lift L is adjusted, the common rail oil injector is reassembled, and a second round of test is carried out; D. calculating the pressure p and the pulse width t of the same pressure chamber in the two-wheel testcLower cycle fuel injection quantity change rate etavDetermining the maximum needle lift L for the first runmaxCorresponding pulse width tc. The invention has the beneficial effects that: fully utilizes conventional test data, analyzes the influence of the maximum needle valve lift, and reducesThe test cost is reduced.
Description
Technical Field
The invention belongs to the field of performance analysis of common rail injectors of diesel engines, and particularly relates to a test method for judging the maximum lift of a needle valve.
Background
The maximum needle valve lift is a key parameter in the design process of the common rail fuel injector, and has influence on the magnitude of the circulating fuel injection quantity and the fuel injection stability. The maximum needle valve lift is designed to be too small, the throttling effect on the seat surface of the fuel injection nozzle matching part is increased, the fuel injection pressure loss is increased, and the improvement of the circulating fuel injection quantity is not facilitated. On the contrary, the maximum needle valve lift is designed to be too large, the needle valve cannot reach the maximum value in the actual oil injection process, and meanwhile due to the influence of pressure, the closing strokes of the needle valves are inconsistent, the closing delay of the needle valves is inconsistent, and the standard deviation of the oil injection quantity of multiple cycles is increased. Therefore, an optimal design of the maximum needle lift design value is required.
The maximum needle valve lift can be optimally designed by using a simulation means, but a simulation model needs to acquire a relevant curve of the needle valve lift in the oil injection process to calibrate the simulation precision. The needle valve lift test is difficult and poor in precision due to the limitation of the common rail fuel injector structure and test means. In order to improve the precision of the simulation model, the simulation model is generally calibrated by test curves such as pressure fluctuation, oil injection law and the like. And performing maximum needle valve lift optimization analysis by using the calibrated model. However, the fuel injection law curve needs a special instrument for testing, and the error of the test result relative to the cycle fuel injection quantity and the fuel injection opening delay is large, so that the maximum needle valve lift optimization analysis is influenced.
Disclosure of Invention
In view of this, the present invention provides a test method for determining a maximum lift of a needle valve, so as to analyze the maximum lift of the needle valve, reduce test cost, and improve analysis accuracy.
In order to achieve the purpose, the technical scheme of the invention is realized as follows:
a test method for judging the maximum lift of a needle valve comprises the following steps:
A. for common rail injector at different pressures p and different pulse widths tcLower cycle fuel injection quantity v, fuel injection duration t and fuel injection opening delay toAnd standard deviation sigma of multi-cycle fuel injection quantityvCarrying out a first round of test;
B. shortening the pulse width tcInterval, cyclic oil injection quantity v and pulse width t in first round of testcThe relationship curve has an inflection point, and the multi-cycle fuel injection standard deviation sigma is combinedvThe maximum needle valve lift L is judged according to the variation trend ofmaxCorresponding pulse width tcThe interval range of (a);
C. after the first round of test is finished, the common rail oil atomizer is disassembled and inspected, the maximum needle valve lift L of the common rail oil atomizer is adjusted, the common rail oil atomizer is reassembled, and a second round of test is carried out according to the control parameters of the first round;
D. calculating the pressure p and the pulse width t of the same pressure chamber in the two-wheel testcLower cycle fuel injection quantity change rate etavBy the pulse width tcAnd cyclic fuel injection quantity change rate etavGenerating a curve by judging the change rate eta of the cyclic fuel injection quantityvDetermining the maximum needle lift L of the first roundmaxCorresponding pulse width tcAnd judging the time for the needle valve to reach the maximum lift under different pressures.
Further, in the step B, the maximum needle lift L of the common rail fuel injector is adjusted to be increased by 30-50%.
Further, before the second round of test, the step B firstly selects three points of 20%, 30% and 40% of the circulating fuel injection amount of the calibration working condition to carry out performance test under the same control parameters, and records the circulating fuel injection amount v of the three pointstFuel injection opening delay toCalculating the change rate eta of the cyclic fuel injection amount before and after the adjustment of the needle valve liftvRate of change of opening delay ηodAt the rate of change eta of the fuel injection quantity in cyclesvAnd rate of change of opening delay etaodAnd carrying out a second round of test under the condition that the change rates of the common rail fuel injectors are within the range of +/-5%, otherwise, reassembling the common rail fuel injectors after the needle valve lift is adjusted.
Further, the change rate of the circulating fuel injection quantity is,
ηv＝(vt-v1)/v1×100，
the rate of change of the fuel injection opening delay is,
ηod＝(tot-to1)/to1×100。
compared with the prior art, the test method for judging the maximum lift of the needle valve has the following advantages:
the test method for judging the maximum lift of the needle valve overcomes the problem that the lift of the needle valve cannot be directly measured, and improves the simulation precision by using test data with relatively small errors in the test; and conventional test data are fully utilized, the influence of the maximum needle valve lift is analyzed, and the test cost is reduced.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
FIG. 1 shows the cyclic oil injection amount under different pressures and different pulse widths in a first round of the present invention;
FIG. 2 is a graph comparing the variation rate of the fuel injection amount and the fuel injection opening delay of the present invention;
FIG. 3 is a standard deviation of fuel injection quantity for the first cycle of the present invention;
FIG. 4 is a diagram showing the variation rate of the fuel injection amount in two cycles;
FIG. 5 is a comparison of fuel injection for two cycles of the present invention.
Detailed Description
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
A test method for judging the maximum lift of a needle valve comprises the following steps:
A. to pairCommon rail injector at different pressures p and different pulse widths tcLower cycle fuel injection quantity v, fuel injection duration t and fuel injection opening delay toAnd standard deviation sigma of multi-cycle fuel injection quantityvCarrying out a first round of test;
B. shortening the pulse width tcInterval, cyclic oil injection quantity v and pulse width t in first round of testcThe relationship curve has an inflection point, and the multi-cycle fuel injection standard deviation sigma is combinedvThe maximum needle valve lift L is judged according to the variation trend ofmaxCorresponding pulse width tcBy reducing the pulse width tcIncreasing the sample size of performance test data, circulating fuel injection quantity v and pulse width tcThe "inflection point" of the relationship curve of (1) is more definite;
C. after the first round of test is finished, the common rail oil atomizer is disassembled and inspected, the maximum needle valve lift L of the common rail oil atomizer is adjusted, the common rail oil atomizer is reassembled, and a second round of test is carried out according to the control parameters of the first round;
D. calculating the pressure p and the pulse width t of the same pressure chamber in the two-wheel testcLower cycle fuel injection quantity change rate etavBy the pulse width tcAnd cyclic fuel injection quantity change rate etavGenerating a curve by judging the change rate eta of the cyclic fuel injection quantityvDetermining the maximum needle lift L of the first roundmaxCorresponding pulse width tcAnd judging the time for the needle valve to reach the maximum lift under different pressures.
And B, adjusting the maximum needle valve lift L of the common rail oil sprayer to increase by 30-50%.
Before the second round of test, selecting three points of 20%, 30% and 40% of the cyclic oil injection amount of the calibration working condition to perform performance test under the same control parameters, and recording the cyclic oil injection amount v of the three pointstFuel injection opening delay toCalculating the change rate eta of the cyclic fuel injection amount before and after the adjustment of the needle valve liftvRate of change of opening delay ηodAt the rate of change eta of the fuel injection quantity in cyclesvAnd rate of change of opening delay etaodIf the change rate is within the range of +/-5 percent, carrying out a second round of test, otherwise, carrying out the test after adjusting the lift of the needle valveThe common rail injector of (1) is reassembled.
The change rate of the circulating fuel injection quantity is,
ηv＝(vt-v1)/v1×100，
the rate of change of the fuel injection opening delay is,
ηod＝(tot-to1)/to1×100。
in the step C, the needle valve lift L reaches the maximum needle valve lift LmaxBack, pressure chamber pressure pvTend to be stable, and meanwhile, the closing stroke of the needle valve is consistent, so that the closing delay t of the needle valve is improvedcdThe consistency of the oil injection duration is improved, the consistency of the multi-cycle oil injection quantity is improved, and the standard deviation sigma of the multi-cycle oil injection quantity is causedvDecrease; needle valve lift L reaches maximum needle valve lift LmaxBack, pressure chamber pressure pvThe stability is trend, the increase factor of the circulating fuel injection quantity v only remains one factor of the fuel injection duration t, and the pulse width t in the test control parameter is shortenedcInterval, cyclic injection quantity v and pulse width tcWill appear as "inflection points" in combination with the standard deviation σvCan judge the maximum needle valve lift LmaxCorresponding pulse width tcThe interval range of (2).
One specific example is given below:
as shown in fig. 1, the common rail injector performance test system is used to complete the average cycle fuel injection quantity performance test of 100 tests for each point under the four pressures of the common rail injector, namely 60MPa, 100MPa, 140MPa and 180MPa, and 21 pulse widths of 300us, 325us and 350us … … 800us, and the test results show that: when the pressure is 60MPa, the increment of the circulating fuel injection quantity is not reduced, which shows that the maximum lift of the fuel injector is not reached under the pressure of 60MPa and the pulse width of 800 us; when the pressure is 100MPa, the increment of the circulating fuel injection quantity is reduced at about 700us, and the control pulse width corresponding to the range of the inflection point interval of the increment of the circulating fuel injection quantity is advanced along with the increase of the pressure.
As shown in fig. 2, the cycle fuel injection amount and the fuel injection opening delay change rate are compared before the second round of test. Regulating fuel injectorsThe maximum needle valve lift parameter is increased from 0.5mm to 0.7mm, then three points of 20%, 30% and 40% of the cyclic oil injection amount under the calibration working condition are selected for performance test under the same control parameters, and the cyclic oil injection amount v of the three points is recordedtAre respectively 49.97mm3、74.06mm3、101.55mm3Cyclic oil injection amount v of three points corresponding to the first round1Are respectively 49.47mm3、72.24mm3、101.74mm3By the formula ηv＝(vt-v1)/v1X 100 calculating three-point circulation fuel injection conversion rate etav1%, 2.46% and-0.19%, respectively. Recording the fuel injection opening delay t at three pointsot402.31us, 407.62us, 409.04us, respectively, three points of fuel injection opening delay t corresponding to the first roundo1403.87us, 417.32us and 418.14us respectively. By delay t of fuel injection openingoRate of change etaod＝(tot-to1)/to1X 100 calculating the rate of change of opening delay eta of three pointsodRespectively-0.39%, -2.32%, -2.18%. Statistical cycle fuel injection quantity conversion rate etavRate of change of opening delay ηodThe rates of change were all within 5%, and a second round of testing was initiated.
As shown in fig. 3, is the pulse width tcIs X coordinate and standard deviation sigma of fuel injection quantity of 100 times circulationvData arrangement is carried out on the Y coordinate, the arrangement result shows that when the pressure p is 60MPa, the standard deviation sigma of the circulating fuel injection quantity isvThe maximum value corresponds to between 700us and 725 us. Standard deviation sigma of circulating fuel injection quantity at 100MPavThe maximum value corresponds to between 700us and 725 us. At 140MPa, standard deviation sigma of circulating fuel injection quantityvThe maximum value corresponds to between 575us and 600 us. 180MPa, standard deviation sigma of circulating fuel injection quantityvThe maximum value corresponds to between 550us and 575 us.
As shown in fig. 4, is the pulse width tcThe same pressure p and the same pulse width t of two tests are taken as an X coordinatecRate of change eta of cyclic fuel injection quantity vvData processing for Y coordinates. For example, the oil injection quantity v of the first round circulation is equal to the oil injection quantity v of the first round circulation when the pressure is 180MPa and the pulse width is 575us1Is 150.65mm3The second round of circulationQuantity of fuel injected v2Is 150.5mm3To obtain etav0.1 percent, the pressure is 180MPa, and the pulse width is 600us, the oil injection quantity v of the first round circulation1Is 171.92mm3Second-round circulation fuel injection quantity v2Is 165.35mm3To obtain etavThe content was found to be 3.82%. The change rate eta of the fuel injection quantity of the two-cycle under the three pressures of 100MPa, 140MPa and 180MPa can be obtained through the graph 4vThe specific control pulse width corresponding to the "inflection point" of (1), such as the control pulse widths of "inflection point" under 100MPa, 140MPa and 180MPa are 725us, 650us and 575us, which means that the needle lift L reaches the maximum needle lift L under the pulse widthmax。
As shown in fig. 5, is the pulse width tcThe same pressure p and the same pulse width t of two tests are taken as an X coordinatecAnd (5) processing data by taking the cyclic fuel injection quantity v as a Y coordinate. Same pulse width tcAfter the needle valve lift L is increased in the second round, the cyclic fuel injection quantity v is increased, which shows that the maximum needle valve lift L designed in the first roundmaxIs small.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (4)
1. A test method for judging the maximum lift of a needle valve is characterized by comprising the following steps:
A. for common rail injector at different pressures p and different pulse widths tcLower cycle fuel injection quantity v, fuel injection duration t and fuel injection opening delay toAnd standard deviation sigma of multi-cycle fuel injection quantityvCarrying out a first round of test;
B. shortening the pulse width tcInterval, cyclic oil injection quantity v and pulse width t in first round of testcThe relationship curve has an inflection point, and the multi-cycle fuel injection standard deviation sigma is combinedvThe maximum needle valve lift L is judged according to the variation trend ofmaxCorresponding pulse width tcThe interval range of (a);
C. after the first round of test is finished, the common rail oil atomizer is disassembled and inspected, the maximum needle valve lift L of the common rail oil atomizer is adjusted, the common rail oil atomizer is reassembled, and a second round of test is carried out according to the control parameters of the first round;
D. calculating the pressure p and the pulse width t of the same pressure chamber in the two-wheel testcLower cycle fuel injection quantity change rate etavBy the pulse width tcAnd cyclic fuel injection quantity change rate etavGenerating a curve by judging the change rate eta of the cyclic fuel injection quantityvDetermining the maximum needle lift L of the first roundmaxCorresponding pulse width tcAnd judging the time for the needle valve to reach the maximum lift under different pressures.
2. The test method for judging the maximum lift of the needle valve according to claim 1, wherein: and B, adjusting the maximum needle valve lift L of the common rail oil sprayer to increase by 30-50%.
3. The test method for judging the maximum lift of the needle valve according to claim 1, wherein: before the second round of test, selecting three points of 20%, 30% and 40% of the cyclic oil injection amount of the calibration working condition to perform performance test under the same control parameters, and recording the cyclic oil injection amount v of the three pointstFuel injection opening delay toCalculating the change rate eta of the cyclic fuel injection amount before and after the adjustment of the needle valve liftvRate of change of opening delay ηodAt the rate of change eta of the fuel injection quantity in cyclesvAnd rate of change of opening delay etaodAnd carrying out a second round of test under the condition that the change rates of the common rail fuel injectors are within the range of +/-5%, otherwise, reassembling the common rail fuel injectors after the needle valve lift is adjusted.
4. The test method for judging the maximum lift of the needle valve according to claim 3, wherein the test method comprises the following steps: the change rate of the circulating fuel injection quantity is,
ηv＝(vt-v1)/v1×100，
the rate of change of the fuel injection opening delay is,
ηod＝(tot-to1)/to1×100。
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114577463A (en) * | 2022-05-05 | 2022-06-03 | 西安航天动力研究所 | Reliability evaluation method of bolt injector |
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| JPH09317592A (en) * | 1996-05-27 | 1997-12-09 | Nissan Motor Co Ltd | Fuel injection controller for diesel engine |
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| JPH09317592A (en) * | 1996-05-27 | 1997-12-09 | Nissan Motor Co Ltd | Fuel injection controller for diesel engine |
| CN103850851A (en) * | 2014-01-26 | 2014-06-11 | 北京博润宏达科技发展有限公司 | Method and system for detecting dynamic lift range of gag bit of common-rail oil injector |
| CN106837580A (en) * | 2017-01-25 | 2017-06-13 | 中国第汽车股份有限公司 | The accuracy control method of common rail system intermediate fuel oil emitted dose |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114577463A (en) * | 2022-05-05 | 2022-06-03 | 西安航天动力研究所 | Reliability evaluation method of bolt injector |
| CN114577463B (en) * | 2022-05-05 | 2022-08-12 | 西安航天动力研究所 | Reliability evaluation method of bolt injector |
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