Test method for testing carbon deposition of light automobile valve burning CNG (compressed natural gas) on rotary drum

Abstract

The invention discloses a method for testing carbon deposition of a light automobile valve burning CNG on a rotary drum, and belongs to the technical field of whole automobile testing. The method comprises the following steps: S1, setting test parameters; s2, vehicle inspection; s3, starting a test; s4, checking the engine; s5, testing the vehicle; and S6, the steps S3-S5 are repeated until valve carbon deposition occurs in the engine, engine ECU electronic injection data are adjusted according to the emission and gas consumption test results and the acceleration test results, so that generation of the valve carbon deposition of the engine is reduced, and generation of the valve carbon deposition of the engine in the running process of an automobile combusting CNG is reduced as much as possible while the economic performance and the dynamic performance are guaranteed. According to the invention, the durability test is carried out on the drum of the CNG-fired vehicle, the carbon deposition condition of the valve is checked in stages, and the emission and gas consumption test and acceleration test are carried out on the tested vehicle. And by continuously correcting and adjusting electronic injection data of the ECU of the engine, carbon deposition of the valve of the engine is reduced, so that a series of problems of power reduction, gas consumption increase, even mechanical damage and the like of the CNG vehicle are reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of whole vehicle testing, and in particular relates to a testing method for testing valve carbon deposits of a CNG-fueled light vehicle on a rotary drum. Background Art

[0002] Vehicles fueled by CNG (compressed natural gas) are more susceptible to carbon deposits due to the fuel's characteristics. Natural gas burns approximately 50°C higher than gasoline and lacks gasoline's self-cleaning properties after combustion (certain components in gasoline can dissolve some carbon deposits). Furthermore, natural gas enters the cylinder in a gaseous state and cannot wet the valve backs the way gasoline does. These factors combine to make CNG vehicles more prone to carbon deposits. Valve carbon deposits are a common problem in internal combustion engines. The gradual accumulation of carbon deposits can affect engine performance, leading to a range of adverse effects, including reduced power, jittery idle, difficulty starting cold, and increased fuel consumption. This significantly impacts the driving experience of CNG vehicles and increases the associated cost of ownership. Summary of the Invention

[0003] The purpose of the present invention is to solve the above-mentioned problems existing in the background technology and to provide a test method for testing carbon deposits on the valves of light-duty vehicles fueled by CNG on a rotary drum.

[0004] The present invention provides a method for testing valve carbon deposits on a CNG-powered light-duty vehicle on a rotating drum. By analyzing various factors, including the vehicle's actual driving route, road conditions, and driving habits, the method simulates and calculates information such as the vehicle's rotational speed, speed, and torque while operating on the drum. A driver assistance system then generates a road profile, and the vehicle undergoes a durability test on the drum according to the generated speed profile. Engine cylinder pressure and valve carbon deposit inspections are performed every 5,000 kilometers. Test vehicle 3 undergoes emissions testing in accordance with the National Sixth Stage Vehicle Pollutant Emission Standard (i.e., China VI), as well as fuel consumption and power performance tests.

[0005] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions: A test method for testing valve carbon deposits on a CNG-fueled light vehicle on a rotary drum comprises the following steps: S1: test parameter setting; S1.1: Collect information on the route, road conditions, average speed, and driver habits of CNG vehicles during actual driving; S1.2: Calculate the engine speed, torque, and vehicle speed during the test through simulation. S1.3: Generate a road profile and a predetermined speed profile using the drum's driver assistance system based on the simulated vehicle speed, engine speed, and torque; S1.4: Determine the simulated drag coefficient of the vehicle traveling on the drum by coasting the vehicle. S2: Vehicle inspection; S2.1: Check the engine oil, tire pressure, and coolant of CNG vehicles for any abnormalities; S2.2: Test the engine cylinder pressure and record it. Check the valves to see if there is any carbon deposit. S2.3: Secure the test vehicle 3 on the drum test bench; S3: Start the experiment; S3.1: Test vehicle 3 is driven cyclically on the drum test bench according to the gear and speed curve; S3.2: The test is suspended when the cumulative driving distance reaches 5000 km; S4: Engine inspection; check the engine cylinder pressure and valve carbon deposits; S5: Vehicle testing; S5.1: Conduct an emission test and a fuel consumption test on test vehicle 3 in accordance with the relevant criteria in standard GB18352.2016; S5.2: In accordance with the relevant standard GB / T12543-2009, test vehicle 3 at three speeds: 0-100 km / h, 60-100 km / h, and full throttle acceleration, and record the travel time for the vehicle to cover a distance of 400 m. S6: Repeat the above steps S3-S5 until valve deposits appear in the engine. Combined with the emission, gas consumption and acceleration test results, adjust the engine ECU electronic fuel injection data to reduce the generation of engine valve deposits.

[0006] Furthermore, in step S1.1, the driver habit information is the degree of vigor of the driver when driving the vehicle, including whether the driver is vigorous when starting and whether the driver is vigorous when braking.

[0007] Furthermore, in step S1.2, the vehicle speed information is obtained through simulation calculation based on the required engine speed; the calculation formula is: vehicle speed = 0.377 × engine speed × tire rolling radius / (transmission ratio × final reduction ratio), 0.377 is the unit conversion coefficient, which converts the speed unit rpm into km / h.

[0008] Furthermore, in step S1.4, the simulated drag coefficient of the vehicle traveling on the drum is obtained by sliding the vehicle, and the specific process is as follows: The vehicle runs at a speed of 100 km / h for 10 minutes to ensure that the vehicle power and transmission system are fully preheated. After preheating, the vehicle handbrake is released and the transmission is placed in neutral. The simulated resistance coefficients f0, f1, and f2 of the vehicle driving on the drum are automatically generated by the vehicle coasting.

[0009] Furthermore, in step S4, the engine cylinder pressure detection and valve carbon deposit inspection include the following steps: S4.1: Remove the spark plug and insert the high-definition endoscope into the combustion chamber. Rotate the lens to focus on the back of the intake valve and observe the carbon deposits. S4.2: Use a cylinder pressure gauge to test. First, warm the engine to normal operating temperature. Then, unplug the ignition coil, remove all spark plugs, and install the cylinder pressure gauge. Record the peak pressure displayed on the cylinder pressure gauge and compare it with the peak pressure recorded before the test.

[0010] Furthermore, in step S4.1, the diameter of the high-definition endoscope is ≤6 mm.

[0011] Furthermore, in step S4.2, the engine is warmed up to a normal operating temperature in the range of 80-95°C.

[0012] Compared with the prior art, the present invention has the following beneficial effects: This method conducts durability tests on CNG-powered vehicles on a rotating drum, periodically inspects valve carbon deposits, and performs emissions, gas consumption, and acceleration tests on the test vehicles. By continuously correcting and adjusting engine ECU electronic fuel injection data, the generation of engine valve carbon deposits is reduced, significantly alleviating a range of issues associated with CNG vehicles, including reduced power, increased gas consumption, and even mechanical damage. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a top view of the test vehicle being tested on the drum test bench; Figure 2 This is the main view of the drum test bench; Figure 3 It is a side view of the drum test bench.

[0014] The names and reference numerals of the components in the above drawings are as follows: Driver assistance system 1, rotating drum 2, test vehicle 3, rotating drum test bench 4. DETAILED DESCRIPTION

[0015] The technical solutions of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0016] Specific implementation method 1: Figure 1-Figure 3As shown, this embodiment describes a test method for testing valve carbon deposits of a light-duty vehicle fueled by CNG on a rotary drum, comprising the following steps: S1: test parameter setting; S1.1: Collect information on the route, road conditions, average speed, and driver habits of CNG vehicles during actual driving; S1.2: Calculate the engine speed, torque, and vehicle speed during the test through simulation. S1.3: Based on the simulated vehicle speed, engine speed, and torque, utilize the driver assistance system 1 of drum 2 (which is compatible with drum 2 and is equipped in all test laboratories equipped with drum 2, and is currently available) to generate a road profile and a predetermined speed profile. S1.4: Calculate the simulated drag coefficient of the vehicle on drum 2 by coasting the vehicle. S2: Vehicle inspection; S2.1: Check the engine oil, tire pressure, and coolant of CNG vehicles for any abnormalities (make sure there are no abnormalities); S2.2: Test the engine cylinder pressure and record it. Check the valves to see if there is any carbon deposit. S2.3: Fix the test vehicle 3 on the drum test bench 4; S3: Start the experiment; S3.1: Test vehicle 3 is driven cyclically on drum test bench 4 according to the gear and speed curve; S3.2: The test is suspended when the cumulative driving distance reaches 5000 km; S4: Engine inspection; Check the engine cylinder pressure and valve carbon deposits; S5: Vehicle testing; S5.1: Conduct an emission test and a fuel consumption test on test vehicle 3 in accordance with the relevant criteria in standard GB18352.2016; S5.2: In accordance with the relevant standard GB / T12543-2009, test vehicle 3 at speeds of 0-100 km / h (0 represents starting from rest), 60-100 km / h, and full throttle acceleration, and record the travel time for the vehicle to cover a distance of 400 m. S6: Repeat the above steps S3-S5 until valve deposits appear in the engine. Combined with the emission, gas consumption and acceleration test results, adjust the engine ECU electronic fuel injection data to reduce the generation of engine valve deposits (while ensuring economy and power, minimize the generation of engine valve deposits during driving of CNG-fueled vehicles).

[0017] Specific implementation method 2: Figure 1-Figure 3As shown, this embodiment is a further explanation of the specific embodiment 1. In the step S1.1, the driver habit information is the intensity of the driver's driving of the vehicle, including whether the start is intense and whether the braking is intense.

[0018] Specific implementation method three: Figure 1-Figure 3 As shown, this embodiment is a further explanation of the specific embodiment 1. In the step S1.2, the vehicle speed information is obtained through simulation calculation based on the required engine speed; its calculation formula is: vehicle speed = 0.377 × engine speed × tire rolling radius / (transmission ratio × final reduction ratio), 0.377 is the unit conversion coefficient, which converts the speed unit rpm into km / h.

[0019] Specific implementation method four: Figure 1-Figure 3 As shown, this embodiment is a further explanation of the specific embodiment 1. In the step S1.4, the simulated drag coefficient of the vehicle traveling on the drum 2 is obtained by sliding the vehicle. The specific process is: The vehicle runs at a speed of 100 km / h for 10 minutes to ensure that the vehicle power and transmission system are fully preheated. After preheating is completed, the vehicle handbrake is released and the transmission is placed in neutral; the simulated resistance coefficients f0, f1, and f2 of the vehicle running on drum 2 are automatically generated by the vehicle coasting.

[0020] Specific implementation method five: Figure 1-Figure 3 As shown, this embodiment is a further explanation of the specific embodiment 1. In the step S4, the engine cylinder pressure detection and valve carbon deposit inspection include the following steps: S4.1: Remove the spark plug and insert the high-definition endoscope into the combustion chamber. Rotate the lens to focus on the back of the intake valve and observe the carbon deposits. S4.2: Use a cylinder pressure gauge to test. First, warm the engine to normal operating temperature. Then, unplug the ignition coil, remove all spark plugs, and install the cylinder pressure gauge. Record the peak pressure displayed on the cylinder pressure gauge and compare it with the peak pressure recorded before the test.

[0021] Specific implementation method six: Figure 1-Figure 3 As shown, this embodiment is a further explanation of the specific embodiment five. In the step S4.1, the diameter of the high-definition endoscope is ≤6 mm.

[0022] Specific implementation method seven: Figure 1-Figure 3 As shown, this embodiment is a further explanation of the specific embodiment 5. In the step S4.2, the engine is heated to a normal operating temperature range of 80-95°C.

[0023] Vehicles fueled by CNG (compressed natural gas) are prone to carbon deposits due to the fuel's characteristics. CNG combustion temperatures are approximately 50°C higher than gasoline, and natural gas enters the cylinder in a gaseous state, unable to wet the valve backs like gasoline does, leading to more severe valve carbon deposits. To address this issue, the present invention employs a testing method: a CNG vehicle is subjected to a durability test on a rotating drum 2. During the test, valve carbon deposits are periodically inspected, and the vehicle is simultaneously tested for emissions, gas consumption, and acceleration. Based on the test results, the engine ECU electronic fuel injection data is continuously optimized to minimize carbon deposits. This minimizes the likelihood of carbon deposit formation while ensuring vehicle emissions, economy, and power, thereby optimizing engine performance.

[0024] illustrate: Drum test bench: also known as chassis dynamometer (existing equipment), is a key equipment used for vehicle dynamic performance, emission testing, fuel consumption testing, etc. It tests the entire vehicle in a laboratory environment by simulating actual road driving resistance.

[0025] CNG-fueled light vehicles: refers to vehicles of categories M1, M2 and N1 with a maximum design gross mass not exceeding 3,500kg, which use CNG (Compressed Natural Gas) as the main fuel.

[0026] Valve deposits: refers to the black colloidal or granular carbon deposits formed on the engine intake and exhaust valves and their surrounding areas due to incomplete combustion of fuel or deposition of oil vapor.

[0027] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other configurations without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations coming within the meaning and range of equivalents of the claims are intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0028] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A test method for testing valve carbon deposits on a CNG-fueled light vehicle on a rotary drum, characterized by: The following steps are involved: S1: test parameter setting; S1.1: Collect information on the route, road conditions, average speed, and driver habits of CNG vehicles during actual driving; S1.2: Calculate the engine speed, torque, and vehicle speed during the test through simulation; S1.3: Based on the simulated vehicle speed, engine speed, and torque, a road profile and a predetermined speed curve are generated using the driver assistance system (1) of the rotating drum (2); S1.4: Calculate the simulated drag coefficient of the vehicle traveling on the drum (2) by sliding the vehicle. S2: Vehicle inspection; S2.1: Check the engine oil, tire pressure, and coolant of CNG vehicles for any abnormalities; S2.2: Test the engine cylinder pressure and record it. Check the valves to see if there is any carbon deposit. S2.3: Fix the test vehicle (3) on the drum test bench (4); S3: Start the experiment; S3.1: The test vehicle (3) is driven on the drum test bench (4) in a cycle according to the gear and speed curve; S3.2: The test is suspended when the cumulative driving distance reaches 5000 km; S4: Engine inspection; Check the engine cylinder pressure and valve carbon deposits; S5: Vehicle testing; S5.1: Conduct emission tests and fuel consumption tests on the test vehicle (3) in accordance with the relevant criteria in standard GB18352.2016; S5.2: In accordance with the relevant standards of GB / T12543-2009, test the test vehicle (3) and record the travel time for the vehicle to travel a distance of 400 m under the following three operating conditions: 0-100 km / h, 60-100 km / h, and full throttle acceleration; S6: Repeat the above steps S3-S5 until valve deposits appear in the engine. Combined with the emission, gas consumption and acceleration test results, adjust the engine ECU electronic fuel injection data to reduce the generation of engine valve deposits.

2. The method for testing valve carbon deposits on a CNG-fueled light vehicle on a rotary drum according to claim 1, characterized in that: In step S1.1, the driver habit information is the degree of vigor of the driver when driving the vehicle, including whether the driver is aggressive when starting and whether the driver is aggressive when braking.

3. The method for testing valve carbon deposits on a CNG-fueled light vehicle on a rotary drum according to claim 1, characterized in that: In step S1.2, vehicle speed information is obtained through simulation calculation based on the required engine speed; the calculation formula is: vehicle speed = 0.377 × engine speed × tire rolling radius / (transmission ratio × final drive ratio), where 0.377 is the unit conversion factor, converting the speed unit rpm to km / h.

4. The method for testing valve carbon deposits on a CNG-fueled light vehicle on a rotary drum according to claim 1, characterized in that: In step S1.4, the simulated drag coefficient of the vehicle traveling on the drum (2) is obtained by sliding the vehicle. The specific process is as follows: The vehicle is run at a speed of 100 km / h for 10 minutes to ensure that the vehicle power and transmission system are fully preheated. After the preheating is completed, the vehicle handbrake is released and the transmission is placed in neutral; by coasting the vehicle, the simulated resistance coefficients f0, f1, and f2 of the vehicle running on the drum (2) are automatically generated.

5. The method for testing valve carbon deposits on a CNG-fueled light vehicle on a rotary drum according to claim 1, characterized in that: In step S4, the engine cylinder pressure detection and valve carbon deposit inspection include the following steps: S4.1: Remove the spark plug and insert the high-definition endoscope into the combustion chamber. Rotate the lens to focus on the back of the intake valve and observe the carbon deposits. S4.2: Use a cylinder pressure gauge to test. First, warm the engine to normal operating temperature. Then, unplug the ignition coil, remove all spark plugs, and install the cylinder pressure gauge. Record the peak pressure displayed on the cylinder pressure gauge and compare it with the peak pressure recorded before the test.

6. The method for testing valve carbon deposits on a CNG-fueled light vehicle on a rotary drum according to claim 5, characterized in that: In step S4.1, the diameter of the high-definition endoscope is ≤6 mm.

7. The method for testing valve carbon deposits on a CNG-fueled light vehicle on a rotary drum according to claim 5, characterized in that: In step S4.2, the engine is warmed up to a normal operating temperature range of 80-95°C.

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