A test method for calibration of engine EGR system

Abstract

The present invention discloses a test method for calibration of an engine EGR system, and the method is as follows: 1. Install the air inlet of an engine exhaust pollutant automatic switching device on the engine intake pipeline and exhaust pipeline respectively, and connect the air outlet of the engine exhaust pollutant automatic switching device to the sampling front end of an emission analyzer; 2. Stabilize the engine under medium load conditions, open the engine intake pipeline air valve, and record the time from the opening of the intake pipeline air valve to the stabilization of the emission analyzer value; 3. Open the engine exhaust pipeline air valve, and record the time from the opening of the exhaust pipeline air valve to the stabilization of the emission analyzer value; 4. Add the opening time of the intake pipeline air valve and the exhaust pipeline air valve to the bench sampling time, set them in the controller of the pipeline automatic switching device, and set the corresponding time on the engine bench. The method improves the calibration efficiency of the EGR system and reduces the time and energy wasted by repeated tests.

Description

Technical Field

[0001] The invention relates to a test method for calibrating an engine EGR system, and in particular to a test method for performing EGR rapid calibration on an engine with an EGR function under an original emission test state of the engine. Background Art

[0002] With the rapid development of the automobile industry and the advocacy of automobile energy-saving concepts, traditional power vehicles are constantly updating their technologies to improve thermal efficiency and reduce pollutant emissions. EGR technology has basically become a standard technology for new engines. On the one hand, EGR technology can increase the intake temperature and has a good warm-up effect on cold engine start-ups, which has a high practical value for urban commuter vehicles. On the other hand, EGR technology can effectively reduce the removal of NOX emission pollutants and improve the environmental protection level. As an engine development company, how to calibrate the EGR system and how to manage the EGR rate are the top priorities of engine calibration.

[0003] When the existing engine test bench calibrates the EGR rate, since the emission analyzer can only perform single-channel testing and cannot achieve dual-channel collection, it is necessary to measure the exhaust concentration of the intake and exhaust at the same time, so that the most accurate EGR rate can be calculated. However, using manual switching pipelines on the test bench is very cumbersome and has great safety hazards. In addition, it takes a long time to achieve the purpose of rapid testing. Summary of the invention

[0004] The purpose of the present invention is to provide a test method for calibration of an engine EGR system. The method is mainly used for calibration of an engine EGR system. Through the rapid calibration of the test method, the calibration efficiency of the EGR system is improved, the time and energy wasted in repeated testing are reduced, and the product development speed is accelerated.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] A test method for calibrating an engine EGR system comprises the following steps:

[0007] Step 1: Install the air inlet of the automatic switching device for engine exhaust pollutants on the engine intake pipe and the engine exhaust pipe respectively, and connect the air outlet of the automatic switching device for engine exhaust pollutants to the sampling front end of the emission analyzer;

[0008] Step 2: Stabilize the engine under medium load conditions, open the engine intake valve, and record the time from the opening of the intake valve to the stabilization of the emission analyzer value;

[0009] Step 3: Open the exhaust valve of the engine and record the time from when the exhaust valve is opened to when the emission analyzer value is stable;

[0010] Step 4. Add the opening time of the intake pipe valve and the exhaust pipe valve to the test bench sampling time, and set them in the controller of the pipeline automatic switching device, and set the corresponding time on the engine test bench. Edit the engine speed every 500rpm and the throttle opening 5% interval working conditions, and the engine test bench can complete the automatic point scanning work.

[0011] Compared with the prior art, the present invention has the following advantages:

[0012] 1. During the test, manual inflation can be avoided, the inflation time is increased due to the long gas pipeline, the gas concentration cannot be accurately controlled, and it cannot be guaranteed whether all the gas in the pipeline in a short time is the sample gas to be tested, which improves the test efficiency and shortens the time of each test.

[0013] 2. Shortening the gas pipeline can reduce the generation of condensed water in the exhaust gas, reduce the occurrence of equipment blockage, and reduce NO X The formation of nitrates in water by pollutants increases the NO X measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is the experimental principle diagram of the automatic switching device for engine exhaust pollutants;

[0015] Figure 2 It is a structural schematic diagram of the gas pipeline automatic switching device;

[0016] In the figure, 1-emission analyzer, 2-gas pipeline automatic switching device, 3-host computer, 4-test gas pipeline inlet end, 5-test gas pipeline exhaust end, 6-engine EGR system, 7-EGR valve, 8-air inlet, 9-gas on-off valve, 10-gas three-way, 11-air outlet, 12-control circuit, 13-relay, 14-timing trigger. DETAILED DESCRIPTION

[0017] The technical solution of the present invention is further described below, but is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be included in the protection scope of the present invention.

[0018] The present invention provides a test method for calibrating an engine EGR system. The air inlet of an engine exhaust pollutant automatic switching device is installed on an engine air intake pipeline and an engine exhaust pipeline respectively, and the air outlet is connected to a sampling front end of an emission analyzer. The engine EGR system is calibrated according to the following steps:

[0019] 1. Stabilize the engine under medium load conditions, open the engine intake valve, and record the time from the opening of the intake valve to the stabilization of the emission analyzer value.

[0020] 2. Open the engine exhaust pipe valve and record the time from the exhaust pipe valve opening to the emission analyzer value stabilizing.

[0021] 3. Add the opening time of the intake pipe valve and the exhaust pipe valve to the bench sampling time, and set them in the controller of the pipeline automatic switching device, and set the corresponding time on the engine bench. Edit the engine speed every 500rpm and the throttle opening 5% interval working conditions, and the engine bench can complete the automatic point scanning work.

[0022] In the present invention, an automatic switching device for engine exhaust pollutants is installed on the pipeline at the front end of the emission analyzer sampling. The automatic switching device is first time calibrated to test the time required for the measured gas to fill the pipeline each time the gas path is switched, and the working time of each pipeline switching of the automatic switching device is set. In this way, the automatic device can cooperate with the engine test bench to quickly complete the scanning and optimization of the EGR rate.

[0023] like Figure 1 As shown, the engine exhaust pollutant automatic switching device includes a gas pipeline automatic switching device 2 and a host computer 3, wherein:

[0024] The air inlet of the gas pipeline automatic switching device 2 is connected to the engine air intake pipeline 4 through the pipeline 1;

[0025] The air inlet of the gas pipeline automatic switching device 2 is connected to the engine exhaust pipeline 5 through the pipeline 2;

[0026] An EGR valve 7 is provided between the engine intake pipe 4 and the engine intake pipe 5;

[0027] The gas pipeline automatic switching device 2 is connected to the emission analyzer 1;

[0028] The host computer 3 is connected to the gas pipeline automatic switching device 2 and is used to control the automatic switching of the gas pipeline between the pipeline 1 and the pipeline 2.

[0029] like Figure 2 As shown, the gas pipeline automatic switching device 2 is composed of an air inlet 8, a gas on-off valve 9, a gas tee 10, an air outlet 11, a control circuit 12, a relay 13, and a timing trigger 14, wherein:

[0030] The air inlet includes a pipeline 1 air inlet and a pipeline 2 air inlet;

[0031] The gas on-off valve 9 includes a pipeline 1 gas on-off valve and a pipeline 2 gas on-off valve;

[0032] One end of the air inlet of pipeline 1 is connected to pipeline 1, and the other end of the air inlet of pipeline 1 is connected to one end of the gas on-off valve of pipeline 1;

[0033] One end of the air inlet of pipeline 2 is connected to pipeline 2, and the other end of the air inlet of pipeline 2 is connected to one end of the gas on-off valve of pipeline 2;

[0034] The gas tee 10 is respectively connected to the other end of the gas on-off valve of pipeline 1, the other end of the gas on-off valve of pipeline 2, and one end of the gas outlet 11;

[0035] The other end of the gas outlet 11 is connected to the emission analyzer 1;

[0036] The gas on-off valve of pipeline 1 and the gas on-off valve of pipeline 2 are connected to the relay 13 via the control circuit 12;

[0037] The relay 13 is connected to the timing trigger 14;

[0038] The timing trigger 14 is connected to the host computer 3 .

[0039] The working principle of the above test gas pipeline automatic switching device is as follows:

[0040] The EGR valve opens, allowing a small amount of exhaust gas to enter the intake manifold and enter the combustion chamber together with the combustible mixture. 2 The concentration is called C CO2进 , CO in the total exhaust gas 2 The concentration is called C CO2总 , C CO2进 / C CO2总 =EGR rate. Measure the intake end CO 2 When the concentration is high, the host computer controls the gas pipeline automatic switching device 2 to automatically switch the gas pipeline to pipeline 1, and then the emission analyzer 1 measures C CO2进 , measure the exhaust end CO 2 When the concentration is high, switch the gas line to line 2 to quickly detect C CO2总 .

Claims

1. A test method for calibrating an engine EGR system, characterized in that The test method comprises the following steps: Step 1: Install the air inlet of the automatic switching device for engine exhaust pollutants on the engine intake pipe and the engine exhaust pipe respectively, and connect the air outlet of the automatic switching device for engine exhaust pollutants to the sampling front end of the emission analyzer; The engine exhaust pollutant automatic switching device comprises a gas pipeline automatic switching device and a host computer, wherein: The air inlet of the gas pipeline automatic switching device is connected to the engine air intake pipeline through pipeline 1; The air inlet of the gas pipeline automatic switching device is connected to the engine exhaust pipeline through pipeline 2; An EGR valve is provided between the engine intake pipe and the engine exhaust pipe; The gas pipeline automatic switching device is connected to the emission analyzer; The host computer is connected to the gas pipeline automatic switching device; The gas pipeline automatic switching device includes an air inlet, a gas on-off valve, a gas tee, an air outlet, a control circuit, a relay, and a timing trigger, wherein: The air inlet comprises a pipeline one air inlet and a pipeline two air inlet; The gas on-off valve comprises a pipeline one gas on-off valve and a pipeline two gas on-off valve; One end of the air inlet of pipeline 1 is connected to pipeline 1, and the other end of the air inlet of pipeline 1 is connected to one end of the gas on-off valve of pipeline 1; One end of the air inlet of pipeline 2 is connected to pipeline 2, and the other end of the air inlet of pipeline 2 is connected to one end of the gas on-off valve of pipeline 2; The gas tee is respectively connected to the other end of the gas on-off valve of pipeline one, the other end of the gas on-off valve of pipeline two, and one end of the gas outlet; The other end of the gas outlet is connected to an emission analyzer; The pipeline one gas on-off valve and the pipeline two gas on-off valve are connected to the relay through a control circuit; The relay is connected to a timing trigger; The timing trigger is connected to the host computer; Step 2: Stabilize the engine under medium load conditions, open the engine intake valve, and record the time from the opening of the intake valve to the stabilization of the emission analyzer value; Step 3: Open the exhaust valve of the engine and record the time from when the exhaust valve is opened to when the emission analyzer value is stable; Step 4. Add the opening time of the intake pipe valve and the exhaust pipe valve to the test bench sampling time, and set them in the controller of the gas pipeline automatic switching device, and set the corresponding time on the engine test bench. Edit the engine speed every 500rpm and the throttle opening 5% interval working conditions, and the engine test bench can complete the automatic point scanning work.

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