阅读说明：本技术 发动机进气管漏气的实时预警方法 (Real-time early warning method for air leakage of air inlet pipe of engine ) 是由 周磊磊 汪荣会 夏秀娟 凌建群 纪丽伟 于 2021-08-20 设计创作，主要内容包括：本发明公开了一种发动机进气管漏气的实时预警方法,包括步骤：1、车载智能终端(1)判断发动机是否处于稳态工况,若是,执行步骤2,若否,等待；2、车载智能终端判断漏气量计算释放条件是否满足,若是,执行步骤3,若否,则返回步骤1；3、车载智能终端计算漏气比值η；4、漏气比值η发送至云端平台(2)；5、云端平台判断漏气比值η是否超过漏气量阈值,若是,执行步骤6,若否,未发生漏气故障；6、车辆ECU(3)判断进气流量传感器(42)是否故障并发送至云端平台；7、云端平台判定进气管发生漏气并推送进气管漏气故障信息。本发明能通过漏气比值实时监控发动机进气管的漏气状态,并在漏气时发出故障预警。(The invention discloses a real-time early warning method for air leakage of an air inlet pipe of an engine, which comprises the following steps: 1. the vehicle-mounted intelligent terminal (1) judges whether the engine is in a steady-state working condition, if so, step 2 is executed, and if not, waiting is carried out; 2. the vehicle-mounted intelligent terminal judges whether the air leakage calculation release condition is met, if yes, step 3 is executed, and if not, the step 1 is returned; 3. calculating an air leakage ratio eta by the vehicle-mounted intelligent terminal; 4. the air leakage ratio eta is sent to the cloud platform (2); 5. the cloud platform judges whether the air leakage ratio eta exceeds an air leakage threshold value, if so, step 6 is executed, and if not, no air leakage fault occurs; 6. the vehicle ECU (3) judges whether the air inlet flow sensor (42) is in fault and sends the fault to the cloud end platform; 7. the cloud platform judges that the air inlet pipe leaks air and pushes air inlet pipe air leakage fault information. The invention can monitor the air leakage state of the air inlet pipe of the engine in real time through the air leakage ratio and send out fault early warning when air leaks.)

1. A real-time early warning method for air leakage of an air inlet pipe of an engine is characterized by comprising the following steps: the real-time early warning method for air leakage of the air inlet pipe of the engine is realized on the basis of an early warning device, wherein the early warning device comprises a vehicle-mounted intelligent terminal (1), a cloud platform (2), a vehicle ECU (3) and an engine (4); the input end of the vehicle-mounted intelligent terminal (1) is electrically connected with the vehicle ECU (3), and the output end of the vehicle-mounted intelligent terminal (1) is wirelessly connected with the cloud platform (2); the engine (4) is electrically connected with the vehicle ECU (3), an intake flow sensor (42) is arranged in an intake pipe (41) of the engine (4), and an upstream nitrogen-oxygen sensor (44) is arranged in an exhaust pipe (43) of the engine (4);

the real-time early warning method for air leakage of the air inlet pipe of the engine comprises the following steps of:

step 1: the vehicle-mounted intelligent terminal (1) judges whether the engine is in a steady-state working condition, if so, step 2 is executed, and if not, the engine is waited to enter the steady-state working condition;

step 2: the vehicle-mounted intelligent terminal (1) judges whether the air leakage calculation release condition is met, if yes, step 3 is executed, and if not, the step 1 is returned;

and step 3: the vehicle-mounted intelligent terminal (1) calculates an air leakage ratio eta of an air inlet pipe (41);

and 4, step 4: the vehicle-mounted intelligent terminal (1) sends the air leakage ratio eta to the cloud platform (2);

and 5: the cloud platform (2) sets an air leakage threshold value, and judges whether the air leakage ratio eta exceeds the air leakage threshold value, if so, the step 6 is executed, and if not, the air inlet pipe (41) has no air leakage fault;

step 6: the vehicle ECU (3) judges whether the air inlet flow sensor (42) has a fault, if so, fault information is sent to the cloud platform (2), and if not, no fault information is sent to the cloud platform (2);

and 7: the cloud platform (2) judges that the air inlet pipe (41) leaks air and pushes air inlet pipe air leakage fault information.

2. The real-time early warning method for air leakage of the air inlet pipe of the engine according to claim 1, which is characterized in that: in step 1, the method for judging whether the engine is in the steady-state working condition comprises the following steps: the vehicle-mounted intelligent terminal (1) sets a threshold value of variable quantity of rotating speed and a threshold value of fuel injection quantity, and the vehicle-mounted intelligent terminal (1) collects the rotating speed w and the fuel injection quantity V of an engine_IAnd judging whether the rotating speed variation within a period of time is lower than a rotating speed variation threshold or not and whether the fuel injection quantity variation is lower than a fuel injection quantity threshold or not, if so, the engine is in a steady-state working condition, and if not, the engine is not in the steady-state working condition.

3. The real-time early warning method for air leakage of the air inlet pipe of the engine according to claim 1,the method is characterized in that: the value range of the speed variation threshold is [ -50rpm, 50rpm]The value range of the threshold value of the fuel injection quantity is [ -10mg/stroke, 10mg/stroke]The vehicle-mounted intelligent terminal (1) collects the rotating speed w and the fuel injection quantity V of the engine_IHas a frequency of 10Hz for a period of 10 s.

4. The real-time early warning method for air leakage of the air inlet pipe of the engine according to claim 1, which is characterized in that: in the step 2, the judgment method for calculating the release condition of the air leakage amount is as follows: the vehicle-mounted intelligent terminal (1) sets an air inflow threshold range, a rotating speed threshold range, an oil injection threshold range and an exhaust pipe upstream oxygen signal threshold range, and the vehicle-mounted intelligent terminal (1) collects the air inflow Q of an engine₂Rotating speed w and fuel injection quantity V_IAnd exhaust pipe upstream oxygen signal measurement Q_oAnd judging whether the following conditions are simultaneously met:

I. intake air quantity Q₂Within an intake air amount threshold range;

II. The rotating speed w is within the rotating speed threshold range;

III, oil injection quantity V_IWithin the range of the threshold value of the fuel injection quantity;

IV, exhaust pipe upstream oxygen signal measurement value Q_oWithin an exhaust pipe upstream oxygen signal threshold range;

if the above conditions are simultaneously satisfied, the air leakage calculation release condition is satisfied, otherwise, the air leakage calculation release condition is not satisfied.

5. The real-time early warning method for air leakage of the air inlet pipe of the engine as claimed in claim 4, wherein: the air input threshold range is more than 200mg/stroke, the rotating speed threshold range is more than 700rpm, the oil injection threshold range is more than 15mg/stroke, and the upstream oxygen signal threshold range of the exhaust pipe is less than 15%; vehicle-mounted intelligent terminal (1) collects air inflow Q of engine₂Rotating speed w and fuel injection quantity V_IAnd exhaust pipe upstream oxygen signal measurement Q_oThe frequency of (2) is 10 Hz.

6. The real-time early warning method for air leakage of the air inlet pipe of the engine as claimed in claim 4, wherein: the step 3 comprises the following steps:

step 3.1: calculating the excess air coefficient lambda according to the measured value of the oxygen signal at the upstream of the exhaust pipe, wherein the calculation formula is as follows:

λ=(1+Q_o/3)/(1-4.77* Q_o) Formula (1);

wherein Q is_oIs an exhaust pipe upstream oxygen signal measurement;

step 3.2: according to the quantity of fuel injected V_ICalculating the actual air input quantity Q by the excess air coefficient lambda₁The calculation formula is as follows:

Q₁=λ*14.3*V_Iformula (2);

step 3.3: according to the air intake quantity Q₂And the actual intake air quantity Q₁Calculating an air intake quantity difference value delta Q, wherein the calculation formula is as follows:

△Q=Q₂-Q₁formula (3);

step 3.4: according to the difference value Delta Q of the air inflow and the air inflow Q₂Calculating an air leakage ratio eta, wherein the calculation formula is as follows:

η=△Q/Q₂equation (4).

7. The real-time early warning method for air leakage of the air inlet pipe of the engine according to claim 1, which is characterized in that: the air leakage threshold range is not less than 0.1.

8. The real-time early warning method for air leakage of the air inlet pipe of the engine according to claim 1, which is characterized in that: the cloud platform (2) is provided with a background memory (21), and the air leakage ratio eta sent to the cloud platform (2) is stored in the background memory (21).

9. The real-time early warning method for the air leakage of the air inlet pipe of the engine according to claim 1 or 8, which is characterized in that: cloud platform (2) be equipped with propelling movement communicator (22), propelling movement communicator (22) propelling movement intake pipe gas leakage fault information.

Technical Field

The invention relates to a fault detection method of an engine, in particular to a real-time early warning method for air leakage of an air inlet pipe of the engine.

Background

The engine air inlet pipe is a pipeline used for sending gas required by engine combustion into an engine, the sealing performance of the engine air inlet pipe is an important factor for ensuring the air inflow of the engine, and after the engine air inlet pipe is used for a long time, the engine air inlet pipe is prone to air leakage and other faults. The vehicle of prior art can't automated inspection engine intake pipe whether take place to leak gas, and the gas leakage detection of engine intake pipe needs to be accomplished through professional check out test set by the professional, and manpower and physics consume great, and often can't guarantee the ageing of detection.

Chinese patent ZL201010600410.1 discloses a device for testing air leakage of an air inlet pipe of a turbocharged engine and an implementation method thereof, and specifically discloses: one or more hollow bolts and a group of nuts matched with the hollow bolts are mounted on the air inlet pipe I and/or the air inlet pipe II; the group of nuts comprises at least one solid nut and a plurality of open nuts, and the open areas of the plurality of open nuts are not completely the same. The air leakage testing method comprises the following steps: firstly, the ratio of the air quantity in the turbocharger to the pressure in the second air inlet pipe is obtained when no air leaks. And then measuring the ratio of the air quantity in the turbocharger to the pressure in the second air inlet pipe under different leakage cross sections. And finally, judging which air leakage cross section area needs to be alarmed according to the running state of the engine and the whole vehicle. Because the air quantity is influenced by the opening degree of the EGR valve, the air leakage condition of an engine model adopting the EGR device can not be judged according to the ratio of the air quantity to the pressure in the second air inlet pipe, and the application range of the device is greatly limited by the model.

Disclosure of Invention

The invention aims to provide a real-time early warning method for air leakage of an air inlet pipe of an engine, which can monitor the air leakage state of the air inlet pipe of the engine in real time through an air leakage ratio and send out fault early warning when air leakage occurs.

The invention is realized by the following steps:

a real-time early warning method for air leakage of an air inlet pipe of an engine is realized on the basis of an early warning device, and the early warning device comprises a vehicle-mounted intelligent terminal, a cloud platform, a vehicle ECU (electronic control unit) and the engine; the input end of the vehicle-mounted intelligent terminal is electrically connected with the vehicle ECU, and the output end of the vehicle-mounted intelligent terminal is wirelessly connected with the cloud platform; the engine is electrically connected with the ECU of the vehicle, an air inlet flow sensor is arranged in an air inlet pipe of the engine, and an upstream nitrogen-oxygen sensor is arranged in an exhaust pipe of the engine;

the real-time early warning method for air leakage of the air inlet pipe of the engine comprises the following steps of:

step 1: the vehicle-mounted intelligent terminal judges whether the engine is in a steady-state working condition, if so, the step 2 is executed, and if not, the engine is waited to enter the steady-state working condition;

step 2: the vehicle-mounted intelligent terminal judges whether the air leakage calculation release condition is met, if yes, step 3 is executed, and if not, step 1 is returned;

and step 3: calculating an air leakage ratio eta of an air inlet pipe by the vehicle-mounted intelligent terminal;

and 4, step 4: the vehicle-mounted intelligent terminal sends the air leakage ratio eta to the cloud platform;

and 5: the cloud platform sets an air leakage threshold value, and judges whether the air leakage ratio eta exceeds the air leakage threshold value, if so, the step 6 is executed, and if not, the air inlet pipe has no air leakage fault;

step 6: the vehicle ECU judges whether the air inlet flow sensor has a fault, if so, fault information is sent to the cloud platform, and if not, no fault information is sent to the cloud platform;

and 7: the cloud platform judges that the air inlet pipe leaks air and pushes air inlet pipe air leakage fault information.

In step 1, the method for judging whether the engine is in the steady-state working condition comprises the following steps: the vehicle-mounted intelligent terminal sets a threshold value of variable quantity of rotating speed and a threshold value of fuel injection quantity, and acquires the rotating speed w and the fuel injection quantity V of the engine_IAnd judging whether the rotating speed variation within a period of time is lower than a rotating speed variation threshold or not and whether the fuel injection quantity variation is lower than a fuel injection quantity threshold or not, if so, judging whether the rotating speed variation is lower than the rotating speed variation threshold or not, and if not, judging whether the rotating speed variation is lower than the fuel injection quantity threshold or not, if so, judging whether the rotating speed variation is lower than the rotating speed variation threshold or notThe engine is in a steady state working condition, if not, the engine is not in the steady state working condition.

The value range of the speed variation threshold is [ -50rpm, 50rpm]The value range of the threshold value of the fuel injection quantity is [ -10mg/stroke, 10mg/stroke]And the vehicle-mounted intelligent terminal acquires the rotating speed w and the fuel injection quantity V of the engine_IHas a frequency of 10Hz for a period of 10 s.

In the step 2, the judgment method for calculating the release condition of the air leakage amount is as follows: the vehicle-mounted intelligent terminal sets an air inflow threshold range, a rotating speed threshold range, an oil injection threshold range and an exhaust pipe upstream oxygen signal threshold range, and acquires the air inflow Q of the engine₂Rotating speed w and fuel injection quantity V_IAnd exhaust pipe upstream oxygen signal measurement Q_oAnd judging whether the following conditions are simultaneously met:

I. intake air quantity Q₂Within an intake air amount threshold range;

II. The rotating speed w is within the rotating speed threshold range;

III, oil injection quantity V_IWithin the range of the threshold value of the fuel injection quantity;

IV, exhaust pipe upstream oxygen signal measurement value Q_oWithin an exhaust pipe upstream oxygen signal threshold range;

if the above conditions are simultaneously satisfied, the air leakage calculation release condition is satisfied, otherwise, the air leakage calculation release condition is not satisfied.

The air input threshold range is more than 200mg/stroke, the rotating speed threshold range is more than 700rpm, the oil injection threshold range is more than 15mg/stroke, and the upstream oxygen signal threshold range of the exhaust pipe is less than 15%; vehicle-mounted intelligent terminal for collecting air inflow Q of engine₂Rotating speed w and fuel injection quantity V_IAnd exhaust pipe upstream oxygen signal measurement Q_oThe frequency of (2) is 10 Hz.

The step 3 comprises the following steps:

step 3.1: calculating the excess air coefficient lambda according to the measured value of the oxygen signal at the upstream of the exhaust pipe, wherein the calculation formula is as follows:

λ=(1+Q_o/3)/(1-4.77* Q_o) Formula (1);

wherein Q is_oIs a rowA tracheal upstream oxygen signal measurement;

step 3.2: according to the quantity of fuel injected V_ICalculating the actual air input quantity Q by the excess air coefficient lambda₁The calculation formula is as follows:

Q₁=λ*14.3*V_Iformula (2);

step 3.3: according to the air intake quantity Q₂And the actual intake air quantity Q₁Calculating an air intake quantity difference value delta Q, wherein the calculation formula is as follows:

△Q=Q₂-Q₁formula (3);

step 3.4: according to the difference value Delta Q of the air inflow and the air inflow Q₂Calculating an air leakage ratio eta, wherein the calculation formula is as follows:

η=△Q/Q₂equation (4).

The air leakage threshold range is not less than 0.1.

The cloud platform is provided with a background memory, and the air leakage ratio eta sent to the cloud platform is stored in the background memory.

The cloud platform be equipped with the propelling movement communicator, the propelling movement communicator propelling movement intake pipe gas leakage fault information.

Compared with the prior art, the invention has the following beneficial effects:

1. the air leakage ratio is calculated based on the oil injection quantity, the air inflow and the exhaust pipe upstream oxygen signal, data do not need to be converted, compared and the like, the air leakage ratio of the air inlet system can be obtained visually, the influence of an EGR device is avoided, the air inlet system is suitable for various engine types, and the universality is high.

2. According to the invention, due to the combination of the vehicle-mounted intelligent terminal and the cloud platform, the running state of the vehicle can be monitored in real time, and fault information is pushed to vehicle owners, maintenance workers and other related personnel when the air leakage of the engine air inlet pipe occurs, so that the fault can be repaired in time before the performance of the vehicle is severely limited, and the overhauling timeliness and the processing efficiency of the engine air inlet pipe are improved, thereby ensuring the running safety of the vehicle and reducing the user loss.

3. The invention limits the vehicle steady state working condition and the air leakage calculation release condition, can ensure the accuracy of air leakage ratio calculation, improves the accuracy of air leakage state judgment of the air inlet pipe of the engine, and avoids misjudgment and missed judgment.

The invention can calculate the air leakage ratio through the collection of vehicle information, and monitor the air leakage state of the air inlet pipe of the engine in real time according to the air leakage ratio, has high air leakage state judgment precision, can send out fault early warning when air leakage occurs, ensures the running safety of the vehicle, and ensures the overhauling timeliness of air leakage faults.

Drawings

FIG. 1 is a flow chart of a real-time early warning method for air leakage of an air inlet pipe of an engine according to the present invention;

FIG. 2 is a schematic diagram of an early warning device adopted by the real-time early warning method for air leakage of the air inlet pipe of the engine.

In the figure, 1 vehicle-mounted intelligent terminal, 2 cloud platforms, 21 background memories, 22 push communicators, 3 vehicle ECUs, 4 engines, 41 air inlet pipes, 42 air inlet flow sensors, 43 exhaust pipes, 44 upstream nitrogen oxygen sensors and 45 tail gas aftertreatment devices.

Detailed Description

The invention is further described with reference to the following figures and specific examples.

A real-time early warning method for air leakage of an air inlet pipe of an engine is realized based on an early warning device, please refer to an attached drawing 2, and the early warning device comprises a vehicle-mounted intelligent terminal (Tbox) 1, a cloud platform 2, a vehicle ECU (Electronic Control Unit, meaning an Electronic Control Unit) 3 and the engine 4; the input end of the vehicle-mounted intelligent terminal 1 is electrically connected with the vehicle ECU 3 through a CAN wire harness, and the output end of the vehicle-mounted intelligent terminal 1 is wirelessly connected with the cloud platform 2 through a communication network; the cloud platform 2 is provided with a background memory 21 and a push communicator 22; the engine 4 is electrically connected with the vehicle ECU 3 through a CAN wire harness, an intake flow sensor 42 is arranged in an intake pipe 41 of the engine 4, an upstream nitrogen and oxygen sensor 44 is arranged in an exhaust pipe 43 of the engine 4, the upstream nitrogen and oxygen sensor 44 is positioned at the upstream of an exhaust gas post-processor 45, and the output end of the intake flow sensor 42 and the output end of the upstream nitrogen and oxygen sensor 44 are electrically connected with the vehicle ECU 3 through the CAN wire harness. The push communicator 22 can realize information push by adopting a 4G mode, a 5G, WIFI mode and the like, and the background memory 21 can adopt a flash memory mode, a database mode and the like.

The real-time early warning method for air leakage of the air inlet pipe of the engine comprises the following steps of:

referring to fig. 1, step 1: and the vehicle-mounted intelligent terminal 1 judges whether the engine is in a steady-state working condition, if so, the step 2 is executed, and if not, the engine is waited to enter the steady-state working condition. The air inflow of the engine is in a relatively stable range under the steady-state working condition, so that the air leakage fault of the air inlet pipe 41 is judged according to the change condition of the air inflow, and the judgment accuracy is ensured.

The method for judging whether the engine is in the steady-state working condition comprises the following steps: the vehicle-mounted intelligent terminal 1 sets a threshold value of the variation of the rotating speed and a threshold value of the fuel injection quantity, and the vehicle-mounted intelligent terminal 1 collects the rotating speed w and the fuel injection quantity V of an engine through the ECU 3 of a vehicle_IAnd judging whether the rotating speed variation within a period of time is lower than a rotating speed variation threshold or not and whether the fuel injection quantity variation is lower than a fuel injection quantity threshold or not, if so, the engine is in a steady-state working condition, and if not, the engine is not in the steady-state working condition.

Preferably, the value range of the rotation speed variation threshold is [ -50rpm, 50rpm ].

Preferably, the value range of the oil injection quantity threshold is [ -10mg/stroke, 10mg/stroke ].

Preferably, the vehicle-mounted intelligent terminal 1 acquires the rotating speed w and the fuel injection quantity V of the engine_IThe frequency of (2) is 10Hz, and the acquisition frequency can be adjusted according to actual needs.

Preferably, the period of time is 10s, and the time range can be adjusted according to actual needs.

Step 2: and the vehicle-mounted intelligent terminal 1 judges whether the air leakage calculation release condition is met, if so, the step 3 is executed, and if not, the step 1 is returned.

Through the setting of the air leakage calculation release condition, the air leakage can be prevented from being calculated under the working condition of small load or the unreasonable measured value of the sensor, so that misleading caused by the inaccuracy of the calculated air leakage is avoided.

The judgment method for the air leakage calculation release condition comprises the following steps: the vehicle-mounted intelligent terminal 1 sets an air inflow threshold range, a rotating speed threshold range, an oil injection threshold range and an exhaust pipe upstream oxygen signal threshold range, and the vehicle-mounted intelligent terminal 1 acquires the air inflow Q of an engine through a vehicle ECU 3₂Rotating speed w and fuel injection quantity V_IAnd exhaust pipe upstream oxygen signal measurement Q_oAnd judging whether the following conditions are simultaneously met:

I. intake air quantity Q₂Within an intake air amount threshold range; intake air quantity Q₂May be measured by the intake air flow sensor 42.

Preferably, the intake air quantity threshold range is more than 200 mg/stroke.

II. The rotating speed w is within the rotating speed threshold range; the rotation speed w can be acquired by the vehicle ECU 3.

Preferably, the rotation speed threshold range is more than 700 rpm.

III, oil injection quantity V_IWithin the range of the threshold value of the fuel injection quantity; oil injection quantity V_IMay be acquired by the vehicle ECU 3.

Preferably, the threshold range of the fuel injection quantity is more than 15 mg/stroke.

IV, exhaust pipe upstream oxygen signal measurement value Q_oWithin an exhaust pipe upstream oxygen signal threshold range; exhaust pipe upstream oxygen signal measurement Q_oAs measured by the upstream nox sensor 44.

Preferably, the threshold range of the exhaust pipe upstream oxygen signal is < 15%.

If the above conditions are simultaneously satisfied, the air leakage calculation release condition is satisfied, otherwise, the air leakage calculation release condition is not satisfied.

Preferably, the vehicle-mounted intelligent terminal 1 collects the air inflow Q₂Rotating speed w and fuel injection quantity V_IAnd exhaust pipe upstream oxygen signal measurement Q_oThe frequency of (2) is 10Hz, and the acquisition frequency can be adjusted according to actual needs.

And step 3: the in-vehicle smart terminal 1 calculates an air leakage ratio η of the intake pipe 41.

Step 3.1: calculating the excess air coefficient lambda according to the measured value of the oxygen signal at the upstream of the exhaust pipe, wherein the calculation formula is as follows:

λ=(1+Q_o/3)/(1-4.77* Q_o) Equation (1).

Wherein Q is_oIs a measurement of the exhaust pipe upstream oxygen signal.

The coefficients 3, 1 and 4.77 are the conversion coefficients of the equivalent hydrogen to carbon ratio and the volume ratio of the diesel fuel into the molar ratio.

The excess air coefficient lambda is the ratio of the actual air intake amount to the theoretical air intake amount required by the complete combustion of 1kg of diesel oil, and the principle of the formula (1) is to calculate the excess air coefficient lambda when the diesel oil is not combusted actually through conversion according to the residual oxygen content in the tail gas after combustion.

Step 3.2: according to the quantity of fuel injected V_ICalculating the actual air input quantity Q by the excess air coefficient lambda₁The calculation formula is as follows:

Q₁=λ*14.3*V_Iequation (2).

14.3kg of fresh air needs to be consumed when 1kg of diesel oil is completely combusted, so the excess air coefficient lambda is multiplied by the fuel injection quantity to obtain the theoretical air intake quantity.

Step 3.3: according to the air intake quantity Q₂And the actual intake air quantity Q₁Calculating an air intake quantity difference value delta Q, wherein the calculation formula is as follows:

△Q=Q₂-Q₁equation (3).

Step 3.4: according to the difference value Delta Q of the air inflow and the air inflow Q₂Calculating an air leakage ratio eta, wherein the calculation formula is as follows:

η=△Q/Q₂equation (4).

The air leakage ratio is calculated based on the oil injection quantity, the air input and the exhaust pipe upstream oxygen signal, processing such as conversion and comparison of various data is not needed, the air leakage ratio of the air inlet system can be quickly, visually and accurately calculated, calculation is simple and quick, the EGR device is not influenced, the EGR device is suitable for various engine models, and universality is high.

And 4, step 4: the vehicle-mounted intelligent terminal 1 sends the air leakage ratio eta to the cloud platform 2, and the air leakage ratio eta is stored in the background memory 21. The air leakage ratio eta calculated each time can be stored in the background memory 21 as historical data of the vehicle and can also be used for comparing with data of other vehicles, so that an air leakage threshold value is set more accurately and the air leakage condition of the air inlet pipe is judged accurately.

And 5: the cloud platform 2 sets an air leakage threshold, and determines whether the air leakage ratio η exceeds the air leakage threshold, if so, step 6 is executed, if not, the air inlet pipe 41 has no air leakage fault, and at this time, no action is executed, and the air leakage ratio η of the next acquisition cycle is waited.

The value range of the air leakage threshold is not less than 0.1, preferably 0.1, and the air leakage threshold can be adjusted according to the judgment precision requirement.

Step 6: the vehicle ECU 3 determines whether the intake air flow sensor 42 is faulty, and if so, transmits fault information to the cloud platform 2, and the cloud platform 2 does not output the air leakage determination result, and if not, transmits no fault information to the cloud platform 2.

The vehicle ECU 3 can collect fault codes of the air inlet flow sensor 42 in real time, whether the collected air inlet flow sensor 42 breaks down or not is confirmed through fault code comparison, the vehicle ECU 3 sends the fault codes to the cloud platform 2 through the vehicle-mounted intelligent terminal 1, if the cloud platform 2 receives the fault codes, the cloud platform 2 does not output air leakage judgment results, and if the cloud platform 2 does not receive the fault codes, the cloud platform 2 outputs air leakage judgment results. The failure state of the intake air flow sensor 42 may be judged in different manners depending on the different forms and kinds of the intake air flow sensor 42 employed, and will not be described here again.

And 7: the cloud platform 2 determines that air leakage occurs in the air inlet pipe 41, and pushes air inlet pipe air leakage fault information through the push communicator 22. The air inlet pipe air leakage fault information can be pushed to vehicle owners, maintenance workers and other related personnel, and air inlet pipe air leakage faults can be conveniently and timely processed.

Example 1:

the engine 4 used in the present embodiment is a 9DF national six engine, and the engine 4 is mounted on a test bench and normally operated.

The invention is adopted to detect and warn whether the air inlet pipe 41 of the engine 4 leaks, and the specific operation flow is as follows:

step 1: the vehicle-mounted intelligent terminal 1 sets a speed variation threshold of 50rpm and an oil injection threshold of 10mg/stroke, and the vehicle-mounted intelligent terminal 1 acquires the speed w and the oil injection V of the engine through the vehicle ECU 3 at an acquisition frequency of 10Hz_IIn 10s, the speed change amount is 35rpm and is lower than the speed change amount threshold value 50rpm, the oil injection amount change amount is 7 mg/stroke and is lower than the oil injection amount threshold value 10mg/stroke, and the engine is in a steady-state working condition.

Step 2: the vehicle-mounted intelligent terminal 1 sets the air inflow threshold range to be more than 200mg/stroke, the rotating speed threshold range to be more than 700rpm, the oil injection threshold range to be more than 15mg/stroke and the exhaust pipe upstream oxygen signal threshold range to be less than 15%, and the vehicle-mounted intelligent terminal 1 collects the air inflow Q of the engine at the collection frequency of 10Hz₂1776 mg/stroke, a rotation speed w of 1090rpm and an oil injection quantity V_IIs 75 mg/stroke and exhaust pipe upstream oxygen signal measurement Q_oThe content was 6.21%.

Intake air quantity Q₂In the range of air inflow threshold value, the rotating speed w is in the range of rotating speed threshold value, and the oil injection quantity V_IIn the range of the threshold value of the fuel injection quantity, the measured value Q of the upstream oxygen signal of the exhaust pipe_oAnd in the range of the upstream oxygen signal threshold of the exhaust pipe, the air leakage calculation release condition is met.

And step 3: the in-vehicle smart terminal 1 calculates an air leakage ratio η of the intake pipe 41.

Step 3.1: calculating the excess air coefficient lambda according to the measured value of the oxygen signal at the upstream of the exhaust pipe, wherein the calculation formula is as follows:

λ=(1+Q_o/3)/(1-4.77* Q_o)=1.45。

step 3.2: according to the quantity of fuel injected V_ICalculating the actual air input quantity Q by the excess air coefficient lambda₁The calculation formula is as follows:

Q₁=λ*14.3*V_I=1555.45mg/stroke。

step 3.3: according to the air intake quantity Q₂And the actual intake air quantity Q₁Calculating an air intake quantity difference value delta Q, wherein the calculation formula is as follows:

△Q=Q₂-Q₁=220.54mg/stroke。

step 3.4: according to the difference value Delta Q of the air inflow and the air inflow Q₂Calculating an air leakage ratio eta, wherein the calculation formula is as follows:

η=△Q/Q₂=0.124。

and 4, step 4: the vehicle-mounted intelligent terminal 1 sends the air leakage ratio eta to the cloud platform 2, and the air leakage ratio eta is stored in the background memory 21.

And 5: the cloud platform 2 sets the air leakage threshold value to be 0.1, and the air leakage ratio eta =0.124 > 0.1.

Step 6: the vehicle ECU 3 collects the fault code of the intake flow sensor 42, determines that the intake flow sensor 42 is not faulty according to the fault code, and sends the fault-free information to the cloud platform 2.

And 7: the cloud platform 2 judges that the air inlet pipe 41 leaks air, and pushes air inlet pipe air leakage fault information to the vehicle owner through the pushing communicator 22, so that the vehicle owner can timely handle air inlet pipe air leakage faults, and the vehicle performance is prevented from being severely limited.

The present invention is not limited to the above embodiments, and any modifications, equivalent replacements, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention.