A method and system for identifying thermal damage to passenger car exhaust pipes

Abstract

The present invention discloses a method and system for identifying thermal damage in passenger vehicle exhaust pipes, comprising the following steps: S1. Establishing a standard time-temperature curve for each exhaust pipe component; S2. Under high-load vehicle conditions, collecting temperature data from each exhaust pipe component and generating a corresponding time-temperature curve; S3. Comparing the time-temperature curve for each exhaust pipe component with the standard time-temperature curve within the same coordinate system, and assessing the thermal damage risk of each exhaust pipe component based on the comparison results. This method can effectively identify potential thermal damage risks in exhaust pipes, while also avoiding design redundancy.

Description

Technical Field

[0001] The present invention relates to the field of automobile safety testing, and in particular to a method and system for identifying thermal damage to an exhaust pipe of a passenger vehicle. Background Art

[0002] The exhaust pipe is located at the bottom of the vehicle, connecting the engine to the outside air. Its primary function is to expel engine exhaust, reduce noise, and purify exhaust gases. High-temperature exhaust gases from the engine flow through the exhaust pipe, causing the exhaust pipe temperature to rise. To achieve this goal, some exhaust pipes are designed with a dedicated downstream catalyst. The oxidation and reduction reactions in the catalyst generate heat, which also causes the exhaust pipe temperature to rise.

[0003] As people's living standards gradually improve, the use of automobiles, as the most common means of transportation, has continued to grow rapidly. However, automobiles are heat sources, and their exhaust pipes, in particular, are directly exposed to the air, which can cause thermal damage. For example, when the car is stopped, the lower surface of the exhaust pipe comes into contact with fibers such as dead grass, causing the dead grass to ignite. Therefore, for the design department, how to prevent thermal damage to the exhaust pipe is a very important issue. Therefore, an effective method for identifying thermal damage to the exhaust pipe is needed to avoid thermal damage, optimize exhaust pipe design, and reduce thermal protection costs. Summary of the Invention

[0004] In order to overcome the deficiencies in the prior art, the present invention proposes a method and system for identifying thermal damage to passenger vehicle exhaust pipes, which can effectively identify potential thermal damage risks to exhaust pipes and avoid waste caused by design redundancy while identifying thermal damage risks.

[0005] In order to solve the above technical problems, the present invention is implemented through the following technical solutions:

[0006] In one aspect, the present invention provides a method for identifying thermal damage to a passenger vehicle exhaust pipe, comprising the following steps:

[0007] S1. Establish standard time-temperature curves for various parts of the exhaust pipe;

[0008] S2. Under high-load vehicle conditions, collect temperature data from various parts of the exhaust pipe and generate corresponding time-temperature curves;

[0009] S3. Compare the time-temperature curve of each part of the exhaust pipe with the standard time-temperature curve in the same coordinate system, and evaluate the thermal damage risk of each part of the exhaust pipe based on the comparison results.

[0010] Preferably, in step S1, the method for constructing the standard time-temperature curve of each part of the exhaust pipe is: in a windless environment, the exhaust pipe is in direct contact with the combustible material, the time required for the combustible material to ignite at each temperature gradient is obtained, and the standard time-temperature curve is fitted.

[0011] Preferably, in step S2, the high-load operating condition of the vehicle includes a climbing condition or a high-speed condition, and the method for collecting temperature data of various parts of the exhaust pipe under the test conditions of the hub platform and the environmental chamber is:

[0012] Warm-up phase;

[0013] Test phase: Drive at a constant speed on a set slope to keep the exhaust pipe temperature constant;

[0014] Measurement phase: Within the set time, the vehicle's driving state is reduced from a constant speed to an idle speed, and the temperature data in the idle state is collected.

[0015] Further preferably, when the vehicle is tested in the hub platform and the environmental chamber, full-load mass sliding resistance data needs to be loaded.

[0016] Preferably, in step S3, the method for evaluating the thermal damage risk of various parts of the exhaust pipe according to different comparison results is:

[0017] Result 1: If the collected time-temperature curve is completely lower than the standard time-temperature curve, it is considered that there is no risk of thermal damage to the corresponding part of the exhaust pipe;

[0018] Result 2: If the collected time-temperature curve is completely higher than or the measurement starting point is higher than the standard time-temperature curve, the corresponding part of the exhaust pipe is considered to be at risk of thermal damage and requires thermal protection treatment;

[0019] Result 3: If the collected time-temperature curve is higher than the standard time-temperature curve, the corresponding part of the exhaust pipe needs to be judged again.

[0020] More preferably, the secondary judgment method is:

[0021] The idling time after the vehicle is started is divided into: a first idling period, a second idling period and a third idling period;

[0022] The time point when the acquisition time-temperature curve is higher than the standard time-temperature curve for the first time;

[0023] If the time node is within the first idle period, the risk of thermal damage is considered high and thermal protection treatment is required;

[0024] If the time node is within the second idle period, it is considered that the thermal damage risk needs to be further judged by the thermal damage risk model;

[0025] If the time node is within the third idle period, the risk of thermal damage is considered low and thermal protection is not required.

[0026] Still further preferably, the proportions of vehicle idling usage scenarios corresponding to the first idle period, the second idle period and the third idle period decrease successively.

[0027] Further preferably, the thermal damage risk model is a risk level database consisting of two dimensions: exposure area and idling period. The risk levels include high risk and low risk. High risk requires thermal protection treatment, while low risk does not require thermal protection treatment.

[0028] In another aspect, the present invention provides a system for identifying thermal damage to an exhaust pipe of a passenger vehicle, the system comprising:

[0029] A collection module, which is used to collect temperature data of various parts of the exhaust pipe;

[0030] a data curve generating module, the data curve generating module being configured to receive the temperature data from the acquisition module and generate the data into a time-temperature curve;

[0031] A display module, the display module is used to display the time-temperature curve generated by the data curve generation module; and

[0032] A judgment module is configured to judge whether there is a risk of thermal damage to the exhaust pipe by comparing the time-temperature curve generated by the data curve generation module.

[0033] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0034] The present invention can effectively identify the risk of thermal damage to the exhaust pipe. In particular, as emission regulations become stricter, more and more exhaust pipes will adopt lower-stage catalysts. Through this method, risk areas can be effectively identified and the cost increase caused by design redundancy can be avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the arrangement of the temperature sensor on the exhaust pipe in an embodiment of the present invention;

[0036] Figure 2 This is a data collection flow chart of an embodiment of the present invention;

[0037] Figure 3 1 is a comparison diagram of the time-temperature curve in the embodiment of the present invention and the standard time-temperature curve;

[0038] Figure 4 This is a heat injury risk model constructed in an embodiment of the present invention;

[0039] Figure 5 This is a diagram of a vehicle idling usage scenario in an embodiment of the present invention;

[0040] Figure 6is a schematic diagram of an exhaust pipe after thermal protection treatment in an embodiment of the present invention;

[0041] Figure 7 This is a comparison diagram of the time-temperature curve collected after the exhaust pipe thermal protection treatment in an embodiment of the present invention and the standard time-temperature curve.

[0042] Reference numerals: 1 - front pipe, 2 - catalytic converter, 3 - muffler, 4 - center exhaust pipe, 5 - thermal insulation layer, 6 - temperature sensor. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted. The positional relationships described in the drawings are only for illustrative purposes and cannot be understood as limitations on this patent. Obviously, the embodiments described are part of the embodiments of the present invention, not all of them. All other embodiments obtained based on the embodiments in the present invention fall within the scope of protection of the present invention.

[0044] In order to better explain the present invention, the following is a detailed description with reference to specific embodiments.

[0045] The method for constructing the standard time-temperature curve for each part of the exhaust pipe is as follows: in a windless environment, the exhaust pipe is in direct contact with the combustible material. Hay is selected as the combustible material, and the time required for the hay to ignite at each temperature gradient is obtained, namely (350s, 300℃), (150s, 400℃), (50s, 500℃), and (25s, 600℃). Through these four sets of data, a smooth standard time-temperature curve is fitted: T = -110.2ln(t) + 945.75.

[0046] like Figure 1 and 2 As shown, prepare the parts, vehicle and equipment for relevant data collection. Arrange the temperature sensor 6 on the lower surface of the exhaust pipe closest to the ground. The temperature sensor 6 needs to be arranged on the lower surface of the front pipe 1, catalyst 2, muffler 3 and middle exhaust pipe 4 of the exhaust pipe.

[0047] Select a vehicle in normal condition and collect the vehicle's fully loaded mass sliding resistance data.

[0048] The environmental chamber needs to be able to control humidity, temperature, and ventilation, and have a rotating hub for the entire vehicle. It can collect temperature data from sensors at a frequency of 1 Hz. The rotating hub for the entire vehicle should have wind speed that can vary with vehicle speed, and can also adjust the slope and sliding resistance.

[0049] In the environmental chamber, the ambient temperature is set at 40°C, the humidity is set at 25-50%, there is no lighting requirement, the air conditioner is set to full cold, blowing on the surface, maximum air volume, A / C (external circulation), and the exhaust exhaust device is connected; the full load condition is achieved through the full load coasting curve.

[0050] Hill climbing and high-speed operating conditions are high-load vehicle operating conditions. Collecting exhaust pipe temperature data for these two conditions is more stringent and representative:

[0051] Climbing conditions:

[0052] Warm-up stage: Accelerate normally to 90-100 km / h and maintain this state for 10 minutes;

[0053] Test phase: Automatic gear acceleration, maintain a speed of 60km / h, 6% slope, and stabilize for 20 minutes or the exhaust system temperature stabilizes, that is, the measured temperature stabilizes within ±5°C; Note: Manual gear should use 3rd gear or other appropriate gear according to the vehicle conditions to ensure stable operation of the vehicle;

[0054] Measurement phase: Idle for 15 minutes. The time from 60 km / h to idle must be completed within 15 seconds, with the start of idle being recorded as the test time "0". If it is not completed within 15 seconds, 15 seconds will be recorded as "0".

[0055] High-speed working conditions:

[0056] Warm-up stage: Accelerate normally to 90-100 km / h and maintain this state for 10 minutes;

[0057] Test phase: Accelerate in automatic mode, maintain a speed of 120 km / h, and maintain a 3% slope for 20 minutes or the exhaust system temperature stabilizes, that is, the measured temperature stabilizes within ±5°C. Note: Manual mode should be shifted to the highest gear normally.

[0058] Measurement phase: Idle for 15 minutes. The test time from 120 km / h to idle must be completed within 20 seconds, with the start of idle being recorded as "0"; if it is not completed within 20 seconds, 20 seconds will be recorded as "0".

[0059] After completing the measurement of the two working conditions, the collected temperature data are recorded in the table to generate the time-temperature curve. Figure 3 As shown in the figure, it can be judged from the figure that the time-temperature curve exceeds the standard time-temperature curve and a secondary judgment is required.

[0060] The secondary judgment needs to be analyzed in combination with the vehicle usage scenario:

[0061] Based on statistical analysis, the corresponding relationship between vehicle idling usage scenarios and idling periods is as follows: after starting, the vehicle idles for 0 to 60 seconds (the first idling period), which cumulatively covers about 91% of the usage scenarios; 60 to 180 seconds (the second idling period), which cumulatively covers about 98% of the usage scenarios; more than 180 seconds (the third idling period), which cumulatively covers about 100% of the usage scenarios, such as Figure 5 As shown in the figure, the first idle period corresponds to a 91% vehicle idle usage scenario, the second idle period corresponds to a 7% vehicle idle usage scenario, and the third idle period corresponds to a 2% vehicle idle usage scenario. The proportions of vehicle idle usage scenarios corresponding to the first, second, and third idle periods decrease in sequence. The vehicle idle usage scenario proportion refers to the proportion of the target population whose vehicles idle within a specific idle period to the total population.

[0062] If the first time the collected temperature curve is higher than the standard time-temperature curve is less than 60 seconds, the risk of thermal injury is considered high and thermal protection treatment is required; if it is between 60 seconds and 180 seconds, the risk of thermal injury needs to be further judged by the thermal injury risk model; if it is greater than 180 seconds, the risk of thermal injury is considered low and no thermal protection is required.

[0063] like Figure 3 As shown, the catalyst downstream of the exhaust pipe exceeded the standard time-temperature curve at 77 seconds (time point), falling between 60 and 180 seconds. This requires a thermal damage model to be used for assessment. The thermal damage risk model uses a risk level database comprised of two dimensions: exposure area and idling period. Risk levels range from high to low. High risk requires thermal protection, while low risk does not require thermal protection.

[0064] The exposed area of the risk zone is about 14dm2, and the exceeding time is 77s. Figure 4 The model judges that it is in a high-risk area and needs to increase thermal protection.

[0065] By adding a heat insulation layer 5 ( Figure 6 ), reducing the exposure area, and through test review, such as Figure 7 As shown in the figure, the time-temperature curve collected again is completely lower than the standard time-temperature curve, and the original risk area has no heat damage risk; at the same time, the exposed area is reduced from 14dm2 to 1dm2, which meets the heat damage model.

[0066] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A method for identifying thermal damage to a passenger car exhaust pipe, characterized in that: The steps include: S1. Establish standard time-temperature curves for various parts of the exhaust pipe; S2. Under high-load vehicle conditions, collect temperature data from various parts of the exhaust pipe and generate corresponding time-temperature curves; S3. Compare the time-temperature curves of various parts of the exhaust pipe with the standard time-temperature curves in the same coordinate system, and assess the thermal damage risk of various parts of the exhaust pipe to the combustion products based on the comparison results; In S3, the method for evaluating the thermal damage risk of various parts of the exhaust pipe to the combustion products based on different comparison results is: Result 1: If the collected time-temperature curve is completely lower than the standard time-temperature curve, it is considered that the corresponding part of the exhaust pipe has no risk of thermal damage to the combustion products; Result 2: If the collected time-temperature curve is completely higher than or the measurement starting point is higher than the standard time-temperature curve, then the corresponding part of the exhaust pipe is considered to have a risk of thermal damage to the combustion products and requires thermal protection treatment; Result 3: If the collected time-temperature curve is higher than the standard time-temperature curve, the corresponding part of the exhaust pipe needs to be re-judged; The secondary judgment method is: The idling time after the vehicle is started is divided into: a first idling period, a second idling period and a third idling period; The time point when the acquisition time-temperature curve is higher than the standard time-temperature curve for the first time; If the time node is within the first idle period, the risk of thermal damage is considered high and thermal protection treatment is required; If the time node is within the second idle period, it is considered that the thermal damage risk needs to be further judged by the thermal damage risk model; If the time node is within the third idle period, the risk of thermal damage is considered low and thermal protection is not required.

2. The method for identifying thermal damage to a passenger vehicle exhaust pipe according to claim 1, characterized in that: In S1, the method for constructing the standard time-temperature curve of each part of the exhaust pipe is: in a windless environment, the exhaust pipe is in direct contact with the combustion material, the time required for the combustion material to ignite at each temperature gradient is obtained, and the standard time-temperature curve is fitted.

3. The method for identifying thermal damage to a passenger vehicle exhaust pipe according to claim 1, wherein: In S2, the high-load operating condition of the vehicle includes a climbing condition or a high-speed condition. The method for collecting temperature data of various parts of the exhaust pipe under the test conditions of the hub platform and the environmental chamber is as follows: Warm-up phase; Test phase: Drive at a constant speed on a set slope to keep the exhaust pipe temperature constant; Measurement phase: Within the set time, the vehicle's driving state is reduced from a constant speed to an idle speed, and the temperature data in the idle state is collected.

4. The method for identifying thermal damage to a passenger vehicle exhaust pipe according to claim 3, wherein: When the vehicle is tested on a rotating hub and in an environmental chamber, the fully loaded mass sliding resistance data must be loaded.

5. The method for identifying thermal damage to a passenger vehicle exhaust pipe according to claim 1, wherein: The proportions of vehicle idling usage scenarios corresponding to the first idling period, the second idling period, and the third idling period decrease in sequence.

6. The method for identifying thermal damage to a passenger vehicle exhaust pipe according to claim 1, wherein: The thermal damage risk model is a risk level database consisting of two dimensions: exposure area and idling period. The risk levels include high risk and low risk. High risk requires thermal protection treatment, while low risk does not require thermal protection treatment.

7. A system for identifying thermal damage to a passenger car exhaust pipe, characterized in that: The system is used to implement the method for identifying thermal damage to a passenger vehicle exhaust pipe according to claim 1, and the system comprises: A collection module, which is used to collect temperature data of various parts of the exhaust pipe; a data curve generating module, the data curve generating module being configured to receive the temperature data from the acquisition module and generate the data into a time-temperature curve; A display module, the display module is used to display the time-temperature curve generated by the data curve generation module; and A judgment module is configured to judge whether the exhaust pipe has a risk of thermal damage to the combustion product by comparing the time-temperature curve generated by the data curve generation module.

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