CN206329372U - A kind of diagnostic device of simulation DPF failures - Google Patents

Abstract

The utility model provides a diagnostic device for simulating DPF failure, which comprises a first mass flowmeter connected to the exhaust pipe of the engine, and first thermocouples are sequentially arranged on the exhaust pipe between the engine and the first mass flowmeter A temperature sensor and a first particle sensor device; the first mass flowmeter communicates with the first flow regulating valve, the first flow regulating valve communicates with the DPF air inlet, and the exhaust pipe of the DPF air outlet is sequentially arranged There is a second thermocouple temperature sensor and a second particle sensor device, and also includes a bypass pipe connected in parallel with the first flow regulating valve and the DPF; by recording the first particle sensor and the second particle sensor under different working conditions and bypass flow The change law of the output voltage of the particulate matter sensor is used to analyze and determine the limit value of the output of the second particulate matter sensor when the DPF is in a complete failure state, and to realize the diagnostic function of simulating the failure of the DPF.

Description

A diagnostic device for simulating DPF failure

technical field

The utility model relates to the field of emission control of internal combustion engines, in particular to a diagnostic device for simulating DPF failure.

Background technique

Diesel engines have the advantages of high thermal efficiency, good fuel economy, good torque characteristics, low emissions, high reliability, and long service life, and are gradually becoming the main power of vehicles. The main pollutants in diesel engine exhaust are nitrogen oxides and particulates, especially particulate emissions, which are very harmful to the human body. Diesel particulate capture technology is currently the most effective post-treatment technology for diesel exhaust particulates recognized internationally, and it is also the exhaust particulate post-treatment technology with the best commercial prospects in the world.

At present, the most widely used type of particle step collector (Diesel Particulate Filter, DPF) is a wall-flow honeycomb ceramic filter body. The inlet and outlet end faces of the carrier are covered with many narrow channels parallel to each other in the axial direction. There is a porous medium wall between them, and the inlet and outlet of each channel are blocked alternately. When the exhaust gas flows through the porous wall, PM is trapped in the porous wall or deposited on the wall. However, when the accumulation of particulate matter inside the DPF continues to increase, the exhaust back pressure of the diesel engine will be too high, which will affect the performance of the diesel engine. Therefore, it is necessary to regenerate the DPF. However, if the regeneration temperature is too high and the temperature gradient is too high, it will cause melting and cracking. At the same time, mechanical vibration will cause damage to the DPF structure, and incomplete regeneration or regeneration failure will cause problems such as DPF blockage. Therefore, failure diagnosis of DPF is required.

The conventional method for diagnosing the failure of a simulated DPF is as follows: installing differential pressure sensors at both ends of the DPF, and judging the degree of failure according to the change of the pressure difference at both ends of the DPF.

Conventional diagnostic devices for simulating DPF failure diagnose the degree of failure based on the DPF pressure difference. The main defect is that it cannot directly measure PM emissions, nor can it effectively detect different failure modes of DPF. In addition, the exhaust back pressure itself is a pulsating signal, and it is very difficult to monitor the exhaust pressure accurately and in real time using a differential pressure sensor in various working environments, and the results are not accurate enough. Therefore, the DPF failure diagnosis method based on pressure difference will be difficult to meet the increasingly stringent OBD standards, and it is necessary to use sensors to directly measure the concentration of particulate matter in the exhaust pipe.

Utility model content

Aiming at the deficiencies in the prior art, the utility model provides a diagnostic device for simulating DPF failure, which aims to solve the problem of inability to directly measure the particle concentration in the exhaust pipe, poor measurement accuracy and inability to detect different DPF failures during the traditional simulation DPF failure diagnosis. model etc.

The utility model realizes above-mentioned technical purpose by following technical means.

A diagnostic device for simulating DPF failure, comprising a first mass flowmeter communicated with an engine exhaust pipe, a first thermocouple temperature sensor and a first Particulate matter sensor device; the first mass flowmeter communicates with the first flow regulating valve, the first flow regulating valve communicates with the DPF air inlet, and the second thermocouple is sequentially arranged on the exhaust pipe of the DPF air outlet The temperature sensor and the second particle sensor device further include a bypass pipe connected in parallel with the first flow regulating valve and the DPF.

Preferably, the front end of the bypass pipe is fixedly connected to the exhaust pipe between the first mass flow meter and the first flow regulating valve, the middle part communicates with the second flow regulating valve and the second mass flow meter in turn, and the rear end is connected to the DPF The exhaust pipe connection at the air outlet end of the

Preferably, the first particle sensor device includes a first stabilizing box communicated with the exhaust pipe, a first air pump communicating with the first stabilizing box, and a first particle sensor communicating with the first air pump;

Preferably, the second particle sensor device includes a second stabilizing box communicated with the exhaust pipe, a second air pump communicating with the second stabilizing box, and a second particle sensor communicating with the second air pump;

Preferably, the first particle sensor device is installed on the engine exhaust pipe through a threaded interface.

Preferably, the second particle sensor device is installed on the engine exhaust pipe through a threaded interface.

Preferably, the first particle sensor and the second particle sensor are leakage current particle sensors.

The utility model cancels the conventional diagnostic method of installing differential pressure sensors at both ends of the DPF, and installs particle sensors on the upstream and downstream of the DPF respectively, and simulates the failure degree of the DPF by controlling the gas flow rate of the bypass pipe, so as to directly measure different failure states PM concentration as well as the purpose of simulating DPF failure diagnosis function.

Compared with the prior art, the utility model has the following advantages:

1. The utility model eliminates the pulsating air flow by installing a steady flow box and an air pump in front of the particle sensor, and realizes steady flow measurement of particle concentration with accurate measurement results.

2. There are flowmeters on the exhaust pipe of the engine and the bypass pipe. The specific exhaust gas leakage can be obtained through the readings of the two flowmeters. The results are accurate and the inaccuracy of conventional diagnostic methods is avoided.

3. The utility model installs a particle sensor device on the upstream and downstream of the DPF, which can directly measure the concentration of PM, with accurate measurement results and small errors. By recording the output voltage changes of the first particle sensor and the second particle sensor under different working conditions and bypass flow rates, analyzing and determining the limit value of the output of the second particle sensor when the DPF completely fails, the diagnostic function of simulating DPF failure is realized.

Description of drawings

FIG. 1 is a structural schematic diagram of a diagnostic device for simulating DPF failure described in the present invention.

Fig. 2 is the curve of the output voltage of the particulate matter sensor measured with time when the engine is 2200 rpm in the utility model.

Among them, 1. The first thermocouple temperature sensor; 2. The first mass flow meter; 3. The first flow regulating valve; 4. DPF; 5. The second flow regulating valve; 6. The second mass flow meter; 7. The first Two thermocouple temperature sensors; 8. The first steady flow box; 9. The first air pump; 10. The first particle sensor; 11. The second steady flow box; 12. The second air pump; 13. The second particle sensor.

detailed description

The utility model will be further described below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the utility model is not limited thereto.

As shown in Figure 1, a diagnostic device for simulating DPF failure includes a first mass flow meter 2 communicated with the exhaust pipe of the engine, and the exhaust pipe between the engine and the first mass flow meter 2 is sequentially provided with A thermocouple temperature sensor 1 and a first particle sensor device; the first particle sensor device includes a first stabilizing box 8 communicated with the exhaust pipe, a first air pump 9 communicating with the first stabilizing box 8 And the first particle sensor 10 communicated with the first suction pump 9; the first mass flow meter 2 is communicated with the first flow regulating valve 3, and the first flow regulating valve 3 is connected with the air inlet of the DPF4, and the The exhaust pipe of the DPF4 air outlet is provided with a second thermocouple temperature sensor 7 and a second particle sensor device in sequence, and the second particle sensor device includes a second stabilizing box 11 communicating with the exhaust pipe, and a second stabilizing box 11 connected to the second stabilizing device. The second air pump 12 communicated with the flow box 11 and the second particle sensor 13 with the second air pump 12; the first flow box 8, the first air pump 9, the second flow box 11, and the second air pump 12 is used to eliminate the pulsating airflow, and realize the measurement of particle concentration in a steady flow state, with accurate measurement results. The first thermocouple temperature sensor 1 and the second thermocouple temperature sensor 8 are used to check the temperature of the two thermocouples measured according to the difference of the exhaust gas temperature after the device is connected to the OBD (on-board diagnostic system). The leakage current signal of the sensor is processed and compensated, so that the first particulate matter sensor 10 and the second particulate matter sensor 13 can both measure correct particulate matter concentration signals at different exhaust temperatures.

The bypass pipe is connected in parallel with the flow regulating valve 3 and the DPF4, the front end of the bypass pipe is fixedly connected to the exhaust pipe between the first mass flow meter 2 and the first flow regulating valve 3, and the middle part is connected to the second The rear end of the flow regulating valve 5 and the second mass flow meter 6 communicates with the exhaust pipe at the air outlet end of the DPF.

Example 1

After the engine is preheated to a steady state, close the second flow regulating valve 5, open the first flow regulating valve 3, and all the exhaust gas discharged from the engine directly passes through the DPF4, at this time simulating the normal working state of the DPF4; then gradually open the flow regulating valve The valve 5 makes part of the exhaust gas flow to the bypass pipe, so that part of the particles flow out with the exhaust gas, the exhaust flow through the DPF4 decreases, the particles captured by the DPF4 decrease accordingly, and the PM concentration detected by the second particle sensor 13 becomes larger , at this time to simulate the state of partial failure of DPF4; as the opening degree of the second flow regulating valve 5 gradually increases, the flow of exhaust gas flowing through the bypass pipe becomes larger and larger, and the first flow regulating valve 3 is completely closed, at this time All the exhaust gas passes through the bypass pipe, and the PM concentration measured by the second particulate matter sensor 13 reaches the limit value, at this time, the complete failure state of the DPF4 is simulated.

The diesel engine operates under steady-state conditions from idling speed to other rotational speeds, record the change law of the output voltage of the second particulate matter sensor 13 under different operating conditions and different flow states of the bypass pipe, and analyze and determine the second particulate matter when the DPF4 completely fails. The limit value output by the sensor 13 realizes the diagnosis function of simulating the failure of the DPF4.

Example 2

On the basis of the method in Example 1, the engine running speed is 2200r/min, the torque is 85Nm, the bypass pipe valve is gradually opened at 60 seconds, and the DPF4 valve is closed at 80 seconds. The output voltage of the second particle sensor 13 is about 0.05V when the exhaust gas passes through the DPF4 in the initial state. After the bypass pipe is opened, the output voltage of the second particle sensor 13 gradually increases to 0.1V. When the DPF4 is completely closed, the output voltage of the second particle sensor 13 is When the limit value reaches about 0.2V, the output voltage of the first particle sensor 10 is about 0.7V. See the curve in Figure 2 for details.

Described embodiment is the preferred embodiment of the present utility model, but the present utility model is not limited to above-mentioned embodiment, under the situation of not departing from the essential content of the present utility model, any obvious improvement that those skilled in the art can make , replacement or modification all belong to the protection scope of the present invention.

Claims (7)

1. a kind of diagnostic device of simulation DPF failures, it is characterised in that including the first quality stream connected with the exhaust pipe of engine The first thermocouple temperature sensor is sequentially provided with gauge (2), the blast pipe between engine and the first mass flowmenter (2) And the first particulate matter sensors device (1)；First mass flowmenter (2) connects with first flow regulating valve (3), and described One flow control valve (3) is connected with DPF (4) air inlet, and the second thermocouple is sequentially provided with the blast pipe of DPF (4) gas outlet Temperature sensor (7) and the second particulate matter sensors device, also including in parallel with the first flow regulating valve (3) and DPF (4) The bypass pipe of connection.

2. the diagnostic device of simulation DPF failures according to claim 1, it is characterised in that the bypass pipe front end is fixed Connection is set successively on the blast pipe between the first mass flowmenter (2) and first flow regulating valve (3), the bypass pipe Put second flow regulating valve (5) and the second mass flowmenter (6), bypass pipe rear end and the discharge duct of DPF (4) outlet port Connection.

3. the diagnostic device of simulation DPF failures according to claim 1, it is characterised in that the first particulate matter sensing Device device includes the first current stabilization box (8) connected with blast pipe, the first aspiration pump (9) connected with the first current stabilization box (8) The first particulate matter sensors (10) connected with the first aspiration pump (9).

4. the diagnostic device of simulation DPF failures according to claim 1, it is characterised in that the second particulate matter sensing Device device includes the second current stabilization box (11) connected with blast pipe, the second aspiration pump connected with the second current stabilization box (11) (12) the second particulate matter sensors (13) and with the second aspiration pump (12) connected.

5. the diagnostic device of simulation DPF failures according to claim 1, it is characterised in that the first particulate matter sensing Device device is arranged on the exhaust pipe of engine by hickey.

6. the diagnostic device of simulation DPF failures according to claim 1, it is characterised in that the second particulate matter sensing Device device is arranged on the exhaust pipe of engine by hickey.

7. the diagnostic device of simulation DPF failures according to claim 1, it is characterised in that the first particulate matter sensing Device (10) and the second particulate matter sensors (13) are using electric leakage streaming particulate matter sensors.