CN115288865A - Method and device for obtaining EGR flow - Google Patents

Abstract

The application discloses a method and a device for acquiring EGR flow, wherein the method comprises the following steps: an exhaust pipe pressure obtained using an exhaust pressure sensor of the EGR system; obtaining exhaust pulse pressure by using the pressure of the exhaust pipe, the fuel injection quantity and the engine speed; acquiring inlet pulse pressure of the Venturi flowmeter by using the exhaust pulse pressure, the inlet temperature of the EGR cooler and the inlet temperature of the EGR valve; and obtaining the exhaust gas flow according to the inlet pulse pressure of the Venturi flowmeter. The technical scheme that this application provided has saved the differential pressure sensor of venturi, has saved the cost. And this application is through calculating the exhaust pulse pressure, can fully consider the flow direction of waste gas, deducts the backward flow of waste gas, and then can more accurately obtain the waste gas flow of forward flow to accurately control exhaust emission according to waste gas flow, and then avoid exhaust emission to exceed standard.

Description

A method and device for obtaining EGR flow

technical field

The present application relates to the technical field of engine emissions, and in particular to a method and device for obtaining EGR flow.

Background technique

Exhaust Gas Recirculation (EGR, Exhaust Gas Recirculation) engines use a Venturi flowmeter to test data, and currently the pressure at the inlet and outlet of the Venturi flowmeter is obtained using a differential pressure sensor. However, in some cases, the differential pressure sensor will have irregular sensor drift, which will lead to inaccurate exhaust gas flow calculation. When the exhaust gas flow calculation is inaccurate, it will cause inaccurate NOx control of the exhaust emission system, thus causing deterioration of fuel consumption.

Contents of the invention

In order to solve the above technical problems, the present application provides a method and device for obtaining EGR flow rate, which can accurately obtain the flow rate of exhaust gas, and then safely discharge exhaust gas.

In order to achieve the above objectives, the technical solutions provided in the embodiments of the present application are as follows:

The application provides a method for obtaining EGR flow, including:

The exhaust pipe pressure obtained by the exhaust pressure sensor of the EGR system;

Using the exhaust pipe pressure, fuel injection quantity and engine speed to obtain exhaust pulse pressure;

Obtaining the inlet pulse pressure of the Venturi flowmeter by using the exhaust pulse pressure, the inlet temperature of the EGR cooler and the inlet temperature of the EGR valve;

The exhaust gas flow rate is obtained according to the inlet pulse pressure of the Venturi flowmeter.

Preferably, said using said exhaust pipe pressure, fuel injection quantity and engine speed to obtain exhaust pulse pressure specifically includes:

Use the engine speed and fuel injection volume as the X-axis and Y-axis of Map respectively;

Obtaining a pulse pressure peak value and a pulse pressure trough value based on the Map and the exhaust pipe pressure;

The exhaust pulse pressure is obtained by using the pulse pressure peak value and the pulse pressure valley value.

Preferably, the obtaining the inlet pulse pressure of the Venturi flowmeter by using the exhaust pulse pressure, the inlet temperature of the EGR cooler and the inlet temperature of the EGR valve specifically includes:

Use the exhaust gas flow rate and the EGR cooler inlet temperature as the horizontal axis and the vertical axis to calibrate the EGR cooler differential pressure Map; use the exhaust gas flow rate and the EGR valve inlet temperature as the horizontal axis and the vertical axis to calibrate the EGR valve differential pressure Map;

The inlet pulse pressure of the Venturi flowmeter is obtained according to the EGR cooler pressure difference Map, the EGR valve pressure difference Map and the exhaust pulse pressure.

Preferably, the obtaining the inlet pulse pressure of the Venturi flowmeter according to the EGR cooler pressure difference Map, the EGR valve pressure difference Map and the exhaust pulse pressure specifically includes:

According to the pulse pressure trough value in the exhaust pulse pressure, the EGR cooler pressure difference Map and the EGR valve pressure difference Map to obtain the Venturi inlet pressure trough value; according to the pulse pressure peak in the exhaust pulse pressure numerical value, the EGR cooler pressure difference Map and the EGR valve pressure difference Map to obtain the venturi inlet pressure peak value;

The inlet pulse pressure of the Venturi flowmeter is obtained according to the trough value of the Venturi inlet pressure and the peak value of the Venturi inlet pressure.

Preferably, the exhaust gas flow rate obtained according to the inlet pulse pressure of the Venturi flowmeter specifically includes:

The exhaust gas flow rate is obtained according to the inlet pulse pressure of the Venturi flowmeter, the inlet pipe pressure, the exhaust gas density, the Reynolds number and the Venturi flow coefficient.

The application provides a device for obtaining EGR flow, including:

an exhaust pipe pressure acquisition unit, used to obtain the exhaust pipe pressure from the exhaust pressure sensor of the EGR system;

an exhaust pulse pressure obtaining unit, configured to obtain the exhaust pulse pressure by using the exhaust pipe pressure, fuel injection quantity and engine speed;

The inlet pulse pressure obtaining unit is used to obtain the inlet pulse pressure of the Venturi flowmeter by using the exhaust pulse pressure, the inlet temperature of the EGR cooler and the inlet temperature of the EGR valve;

The exhaust gas flow obtaining unit is used to obtain the exhaust gas flow according to the inlet pulse pressure of the Venturi flowmeter.

Preferably, the exhaust pulse pressure obtaining unit is specifically configured to use the engine speed and fuel injection quantity as the X-axis and Y-axis of Map respectively; obtain the pulse pressure peak value and pulse pressure based on the Map and the exhaust pipe pressure Pressure trough value: the exhaust pulse pressure is obtained by using the pulse pressure peak value and the pulse pressure trough value.

Preferably, the inlet pulse pressure obtaining unit is specifically used to use the exhaust gas flow and the EGR cooler inlet temperature as the horizontal axis and the vertical axis to calibrate the EGR cooler pressure difference Map; the exhaust gas flow and the EGR valve inlet temperature respectively as the horizontal axis and the vertical axis to calibrate the EGR valve pressure difference Map; according to the EGR cooler pressure difference Map, the EGR valve pressure difference Map and the exhaust pulse pressure, the inlet pulse pressure of the Venturi flowmeter is obtained.

Preferably, the inlet pulse pressure obtaining unit obtains the inlet pulse pressure of the Venturi flowmeter according to the EGR cooler pressure difference Map, the EGR valve pressure difference Map and the exhaust pulse pressure, specifically comprising: according to the The pulse pressure trough value in the exhaust pulse pressure, the EGR cooler pressure difference Map and the EGR valve pressure difference Map obtain the Venturi inlet pressure trough value; according to the pulse pressure peak value in the exhaust pulse pressure, The EGR cooler pressure difference Map and the EGR valve pressure difference Map obtain the peak value of the Venturi inlet pressure;

The inlet pulse pressure of the Venturi flowmeter is obtained according to the trough value of the Venturi inlet pressure and the peak value of the Venturi inlet pressure.

Preferably, the exhaust gas flow obtaining unit is specifically configured to obtain the exhaust gas flow according to the inlet pulse pressure of the Venturi flowmeter, the inlet pipe pressure, the exhaust gas density, the Reynolds number and the Venturi flow coefficient.

It can be seen from the above technical scheme that the present application has the following beneficial effects:

The method for acquiring the EGR flow provided by the present application saves the Venturi differential pressure sensor and saves the cost. Moreover, by calculating the exhaust pulse pressure, the application can fully consider the flow direction of the exhaust gas, deduct the reverse flow of the exhaust gas, and then obtain the exhaust gas flow in the forward direction more accurately, so as to accurately control the exhaust gas discharge according to the exhaust gas flow, thereby avoiding The exhaust emission exceeds the standard.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are For some embodiments of the present application, those of ordinary skill in the art can also obtain other drawings based on these drawings without creative effort.

Fig. 1 is the schematic diagram of a kind of EGR system provided by the application;

Fig. 2 is a flow chart of a method for obtaining EGR flow provided by the present application;

Fig. 3 is a schematic diagram of exhaust pulse pressure and Venturi inlet pulse pressure provided by the present application;

Figure 4 is a framework diagram for obtaining the exhaust pulse pressure provided by the present application;

Fig. 5 is the trough architecture diagram of obtaining the Venturi inlet pulse pressure provided by the present application;

FIG. 6 is a peak structure diagram for obtaining Venturi inlet pulse pressure provided by the present application;

Figure 7 is a framework diagram for obtaining exhaust gas flow provided by the present application;

Fig. 8 is a schematic diagram of an EGR flow acquisition device provided by an embodiment of the present application.

Detailed ways

In order to help better understand the solutions provided in the embodiments of the present application, before introducing the methods provided in the embodiments of the present application, first introduce the application scenarios of the solutions in the embodiments of the present application.

Referring to FIG. 1 , this figure is a schematic diagram of an EGR system provided by the present application.

It can be seen from Fig. 1 that an exhaust pressure sensor 10 (abbreviated as exhaust pipe pressure P) is installed on the exhaust pipe, which is connected to the EGR cooler 20 in sequence along the flow direction of the exhaust gas (there may be a check valve behind it (or No check valve, depends on the system)), after EGR cooler temperature sensor 30, EGR valve 40, Venturi flow meter 50, intake pressure on the intake manifold (referred to as intake pressure P_in) and temperature sensor 60.

Wherein, Cyl1-Cyl6 are six cylinders of the engine.

Since in the exhaust gas discharge process, there may be backflow of exhaust gas, that is, backflow, sometimes it may flow from top to bottom, and sometimes it may flow from bottom to top. Therefore, in order to obtain the flow rate of exhaust gas accurately, the application needs to identify the flow direction of exhaust gas , the difference between the two directions can get the accurate exhaust gas flow. The technical solutions provided by the present application will be described in detail below in conjunction with the accompanying drawings. In addition, in order to save costs, this application omits the differential pressure sensor of Venturi, but obtains the pressure difference between the inlet and outlet of Venturi through calculation. Since the cost of the differential pressure sensor is relatively high, the technical solution provided by this application can also cut costs.

In order to make the above objects, features and advantages of the present application more obvious and understandable, the embodiments of the present application will be further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

Referring to FIG. 2 , this figure is a flow chart of a method for obtaining EGR flow provided by the present application.

The methods for obtaining EGR flow provided by this application include:

S201: using the exhaust pipe pressure obtained by the exhaust pressure sensor of the EGR system;

Since the EGR system is equipped with an exhaust pressure sensor, the exhaust pipe pressure can be obtained directly through the exhaust pressure sensor.

S202: Obtain exhaust pulse pressure by using the exhaust pipe pressure, fuel injection quantity and engine speed;

For a multi-cylinder diesel engine, the pressure on the exhaust side repeats in a certain regular pressure pulsation with the opening and closing of the exhaust valve (abbreviated as exhaust pulse pressure). That is, the actual exhaust pulse pressure is in a pulsating form, for example, the waveform of the exhaust pressure is similar to a sine wave.

Since the exhaust pulse pressure is in the form of pulses, there are peaks and valleys, and it is necessary to obtain the peaks and valleys of the exhaust pulse pressure according to the fuel injection quantity and the engine speed.

Due to the backflow of exhaust gas, the exhaust pulse pressure can represent the flow direction of exhaust gas in the form of pulse fluctuations. When the exhaust pulse pressure is greater than the intake pressure, it means that the exhaust gas flow direction is positive, that is, the exhaust gas flows from On the contrary, when the exhaust pulse pressure is lower than the intake pressure, it means that the exhaust gas flow direction is reversed, that is, the exhaust gas flows from bottom to top. If the forward flow of exhaust gas is positive and the reverse flow is negative, then the total flow should be the sum of positive and negative. Obviously, after considering the flow direction of the exhaust gas in this application, the exhaust gas flow rate can be obtained more accurately, and then the exhaust gas emission can be controlled to avoid excessive exhaust gas emission.

S203: Obtain the inlet pulse pressure of the Venturi flowmeter by using the exhaust pulse pressure, the inlet temperature of the EGR cooler and the inlet temperature of the EGR valve;

Since there are EGR cooler, EGR cooled temperature sensor and EGR valve between the exhaust pipe and the inlet of the Venturi flowmeter, the inlet pulse pressure of the Venturi flowmeter needs to be determined according to the exhaust pulse pressure, the inlet temperature of the EGR cooler and EGR valve inlet temperature to obtain.

Since the exhaust pulse pressure is a sine wave, the inlet pressure of the Venturi flowmeter is also in the form of a pulse, which becomes the inlet pulse pressure of the Venturi flowmeter.

S204: Obtain the exhaust gas flow rate according to the inlet pulse pressure of the Venturi flowmeter.

Since the inlet pipe pressure becomes the outlet pressure of the Venturi flowmeter, the exhaust gas flow rate can be obtained according to the inlet pipe pressure, the inlet pulse pressure of the Venturi flowmeter, the preset coefficient, and the exhaust gas density.

The method for acquiring the EGR flow provided by the present application saves the Venturi differential pressure sensor and saves the cost. Moreover, by calculating the exhaust pulse pressure, the application can fully consider the flow direction of the exhaust gas, deduct the reverse flow of the exhaust gas, and then obtain the exhaust gas flow in the forward direction more accurately, so as to accurately control the exhaust gas discharge according to the exhaust gas flow, thereby avoiding The exhaust emission exceeds the standard.

The specific process of obtaining the exhaust pulse pressure and the Venturi inlet pulse pressure in this application will be respectively introduced below in conjunction with the accompanying drawings.

Refer to FIG. 3 , which is a schematic diagram of exhaust pulse pressure and Venturi inlet pulse pressure provided by the present application.

It can be seen from the figure that the two sine waves included are the exhaust pulse pressure and the corrected Venturi inlet pulse pressure respectively. It should be understood that these two sine waves are obtained through calculation in this application and cannot be directly obtained by the sensor. measured. In addition, the pulse pressure peak value and pulse pressure valley value corresponding to the exhaust pulse pressure are also calibrated in the figure. Wherein, both the intake pressure P_in and the exhaust pipe pressure P can be directly measured by sensors.

The exhaust pulse pressure is obtained by using the exhaust pipe pressure, fuel injection quantity and engine speed, specifically including:

Use the engine speed and fuel injection volume as the X-axis and Y-axis of Map respectively;

Obtaining a pulse pressure peak value and a pulse pressure trough value based on the Map and the exhaust pipe pressure;

The exhaust pulse pressure is obtained by using the pulse pressure peak value and the pulse pressure valley value.

Referring to FIG. 4 , this figure is a structural diagram for obtaining the exhaust pulse pressure provided by the present application.

Since the exhaust pressure exists in the form of pulsation, the exhaust pressure will have a great impact on the accuracy of the entire exhaust gas flow, so it is necessary to correct the time-average pressure P (exhaust pipe pressure) to capture the impact of the pulse on the exhaust gas flow, The exhaust pulse pressure has a peak value P_peak and a trough value P_tough, so the following two parameters are defined, the pulse peak coefficient C_pulse and the pulse trough coefficient C_Trough:

C_pulse=(P_peak-P)/P;

C_Trough=(P-P_tough)/P;

The pulse peak coefficient C_pulse and the pulse valley coefficient C_Trough are calibrated into two Maps (Peak_Map and Tough_Map) respectively, and the X and Y axes of the Map are the engine speed and the fuel injection volume respectively. Based on the calibrated Map and the exhaust pipe pressure P tested by the exhaust pressure sensor, the pulse pressure peak value P_peak and the pulse pressure trough value P_tough can be obtained in real time, and the calibration variable is also required to be the exhaust valve opening duration Valve_timing_C (this is a design constant) , The number of engine cylinders Cyl_num (determines the number of repetitions of the pulse wave), the ignition interval Angel_Firing is 720/Cyl_num degrees, and the function of the exhaust pulse pressure sine wave can be obtained according to the above parameters.

Along the flow direction of the exhaust gas, the EGR cooler differential pressure Map (the horizontal axis is the exhaust gas flow rate, the vertical axis is the temperature after the EGR cooler) and the EGR valve differential pressure Map (the horizontal axis is the exhaust gas flow rate, and the vertical axis is the temperature after the EGR cooler) are calibrated in the engine. EGR valve inlet temperature), based on Map, the pressure difference of key components can be quickly solved, so as to solve the venturi inlet pressure peak value and inlet pressure trough value, combined with the opening duration and ignition interval, etc., the venturi inlet pulse pressure can be obtained .

Refer to Fig. 5, which is a structure diagram of the trough for obtaining the venturi inlet pulse pressure provided by the present application.

Using the exhaust pulse pressure, EGR cooler inlet temperature and EGR valve inlet temperature to obtain the inlet pulse pressure of the Venturi flowmeter, specifically including:

Use the exhaust gas flow rate and the EGR cooler inlet temperature as the horizontal axis and the vertical axis to calibrate the EGR cooler differential pressure Map; use the exhaust gas flow rate and the EGR valve inlet temperature as the horizontal axis and the vertical axis to calibrate the EGR valve differential pressure Map;

The inlet pulse pressure of the Venturi flowmeter is obtained according to the EGR cooler pressure difference Map, the EGR valve pressure difference Map and the exhaust pulse pressure.

Similarly, similar to obtaining the exhaust pulse pressure, it is necessary to obtain the inlet pulse pressure of the Venturi flowmeter according to the exhaust pipe pressure, intake pressure and exhaust pulse pressure.

First, Fig. 5 shows the process of the trough value P_low_venturi of the venturi inlet pressure. The EGR cooler pressure difference Map is obtained from the exhaust gas flow and the EGR cooler inlet temperature, and the EGR valve pressure difference Map is obtained from the exhaust gas flow and the EGR valve inlet temperature. The coefficient P_diff_egrc is obtained from the EGR cooler pressure difference Map, and the coefficient P_diff_value is obtained from the EGR valve pressure difference Map. Then, according to the pulse pressure trough value P_tough of the exhaust pressure, the coefficient P_diff_egrc and the coefficient P_diff_value, the Venturi inlet pressure trough value P_low_venturi is obtained.

Refer to Fig. 6, which is a peak structure diagram for obtaining the venturi inlet pulse pressure provided by the present application.

Figure 5 describes the acquisition of the trough value of the Venturi inlet pressure P_low_venturi, and Figure 6 describes the acquisition of the peak value of the Venturi inlet pressure P_high_ven.

The difference between comparing Figure 6 and Figure 5 is that the peak value P_high_ven of the Venturi inlet pressure in Figure 6 is obtained using the pulse pressure peak value P_peak, coefficient P_diff_egrc, and coefficient P_diff_value of the exhaust pressure, and the others are the same as those in Figure 5, and will not be repeated here. repeat.

Referring to FIG. 7 , this figure is a structural diagram for obtaining exhaust gas flow provided by the present application.

Based on the Venturi inlet pulse pressure and intake pipe pressure obtained above, the real-time pressure difference value before and after the Venturi flowmeter can be obtained. If the system has a check valve, the logic for calculating the exhaust gas flow only applies to the area where the pressure difference value is greater than 0 Integrate, if the system does not have a check valve, it needs to be integrated for the entire cycle. According to the average value P1 of the inlet of the Venturi flowmeter and the pressure of the intake pipe, the temperature T after the EGR cooler, and the gas constant R, the exhaust gas density ρ=P1/(R*T) can be obtained. According to the assumed exhaust gas flow m, Venturi Design the geometric parameter d (constant value) of the nozzle and the exhaust gas density ρ to get the Reynolds number Re of the airflow inside the Venturi. Based on the relationship between the Reynolds number and the Venturi flow coefficient, the flow rate of the Venturi flowmeter under this working condition can be obtained Coefficient Cd, based on exhaust gas density, pressure difference before and after Venturi, flow coefficient, and exhaust gas incompressibility correction coefficient, can be integrated in real time to obtain the exhaust gas flow rate in the entire working cycle. This exhaust gas flow rate is compared with the assumed exhaust gas flow rate in real time. Finally, both The error rate is less than 0.05%, that is, the calculation is considered to be convergent, and the exhaust gas flow value obtained at this time is an accurate value.

Since the technical solution provided by the present application can accurately obtain the exhaust gas flow rate, the exhaust gas emission can be controlled according to the accurate exhaust gas flow rate, thereby improving the exhaust gas emission quality and avoiding excessive exhaust gas emission.

Based on the method for obtaining EGR flow provided by the above embodiments, the present application also provides a device for obtaining EGR flow, which will be described in detail below with reference to the accompanying drawings.

Referring to FIG. 8 , this figure is a schematic diagram of an EGR flow acquisition device provided by an embodiment of the present application.

The acquisition device of the EGR flow provided by this embodiment includes:

Exhaust pipe pressure obtaining unit 801, used to obtain the exhaust pipe pressure by using the exhaust pressure sensor of the EGR system;

Since the EGR system is equipped with an exhaust pressure sensor, the exhaust pipe pressure can be obtained directly through the exhaust pressure sensor.

The exhaust pulse pressure obtaining unit 802 is used to obtain the exhaust pulse pressure by using the exhaust pipe pressure, fuel injection quantity and engine speed;

For a multi-cylinder diesel engine, the pressure on the exhaust side repeats in a certain regular pressure pulsation with the opening and closing of the exhaust valve (abbreviated as exhaust pulse pressure). That is, the actual exhaust pulse pressure is in a pulsating form, for example, the waveform of the exhaust pressure is similar to a sine wave.

Since the exhaust pulse pressure is in the form of pulses, there are peaks and valleys, and it is necessary to obtain the peaks and valleys of the exhaust pulse pressure according to the fuel injection quantity and the engine speed.

Due to the backflow of exhaust gas, the exhaust pulse pressure can represent the flow direction of exhaust gas in the form of pulse fluctuations. When the exhaust pulse pressure is greater than the intake pressure, it means that the exhaust gas flow direction is positive, that is, the exhaust gas flows from On the contrary, when the exhaust pulse pressure is lower than the intake pressure, it means that the exhaust gas flow direction is reversed, that is, the exhaust gas flows from bottom to top. If the forward flow of exhaust gas is positive and the reverse flow is negative, then the total flow should be the sum of positive and negative. Obviously, after considering the flow direction of the exhaust gas in this application, the exhaust gas flow rate can be obtained more accurately, and then the exhaust gas emission can be controlled to avoid excessive exhaust gas emission.

The inlet pulse pressure obtaining unit 803 is used to obtain the inlet pulse pressure of the Venturi flowmeter by using the exhaust pulse pressure, the inlet temperature of the EGR cooler and the inlet temperature of the EGR valve;

Since there are EGR cooler, EGR cooled temperature sensor and EGR valve between the exhaust pipe and the inlet of the Venturi flowmeter, the inlet pulse pressure of the Venturi flowmeter needs to be determined according to the exhaust pulse pressure, the inlet temperature of the EGR cooler and EGR valve inlet temperature to obtain.

Since the exhaust pulse pressure is a sine wave, the inlet pressure of the Venturi flowmeter is also in the form of a pulse, which becomes the inlet pulse pressure of the Venturi flowmeter.

The exhaust gas flow obtaining unit 804 is configured to obtain the exhaust gas flow according to the inlet pulse pressure of the Venturi flowmeter.

Since the inlet pipe pressure becomes the outlet pressure of the Venturi flowmeter, the exhaust gas flow rate can be obtained according to the inlet pipe pressure, the inlet pulse pressure of the Venturi flowmeter, the preset coefficient, and the exhaust gas density.

The EGR flow acquisition device provided by the present application saves the Venturi differential pressure sensor and saves costs. Moreover, by calculating the exhaust pulse pressure, the application can fully consider the flow direction of the exhaust gas, deduct the reverse flow of the exhaust gas, and then obtain the exhaust gas flow in the forward direction more accurately, so as to accurately control the exhaust gas discharge according to the exhaust gas flow, thereby avoiding The exhaust emission exceeds the standard.

The exhaust pulse pressure obtaining unit is specifically used to use the engine speed and fuel injection quantity as the X-axis and Y-axis of Map respectively; obtain the pulse pressure peak value and the pulse pressure valley value based on the Map and the exhaust pipe pressure; use The pulse pressure peak value and the pulse pressure valley value obtain the exhaust pulse pressure.

The inlet pulse pressure acquisition unit is specifically used to calibrate the EGR cooler pressure difference Map using the exhaust gas flow rate and the EGR cooler inlet temperature as the horizontal axis and the vertical axis respectively; use the exhaust gas flow rate and the EGR valve inlet temperature as the horizontal axis and the vertical axis to calibrate the EGR Valve pressure difference Map: obtain the inlet pulse pressure of the Venturi flowmeter according to the EGR cooler pressure difference Map, the EGR valve pressure difference Map and the exhaust pulse pressure.

The inlet pulse pressure obtaining unit obtains the inlet pulse pressure of the Venturi flowmeter according to the EGR cooler pressure difference Map, the EGR valve pressure difference Map and the exhaust pulse pressure, specifically including: according to the exhaust pulse pressure The pulse pressure trough value, the EGR cooler pressure difference Map and the EGR valve pressure difference Map obtain the Venturi inlet pressure trough value; according to the pulse pressure peak value in the exhaust pulse pressure, the EGR cooler The pressure difference Map and the EGR valve pressure difference Map obtain the peak value of the Venturi inlet pressure;

The inlet pulse pressure of the Venturi flowmeter is obtained according to the trough value of the Venturi inlet pressure and the peak value of the Venturi inlet pressure.

The exhaust gas flow obtaining unit is specifically used to obtain the exhaust gas flow according to the inlet pulse pressure of the Venturi flowmeter, the inlet pipe pressure, the exhaust gas density, the Reynolds number and the Venturi flow coefficient.

From the above description of the implementation manners, it can be seen that those skilled in the art can clearly understand that all or part of the steps in the methods of the above embodiments can be implemented by means of software plus a necessary general hardware platform. Based on this understanding, the essence of the technical solution of this application or the part that contributes to the prior art can be embodied in the form of software products, and the computer software products can be stored in storage media, such as ROM/RAM, disk , optical disc, etc., including several instructions to make a computer device (which can be a personal computer, a server, or a network communication device such as a media gateway, etc.) execute the various embodiments or some parts of the embodiments of the present application. method.

It should be noted that each embodiment in this specification is described in a progressive manner, each embodiment focuses on the differences from other embodiments, and the same and similar parts of each embodiment can be referred to each other. As for the method disclosed in the embodiment, since it corresponds to the system disclosed in the embodiment, the description is relatively simple, and for the related part, please refer to the description of the system part.

It should also be noted that in this document, the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article or apparatus comprising a set of elements includes not only those elements , but also includes other elements not expressly listed, or also includes elements inherent in such process, method, article or equipment. Without further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article or apparatus comprising said element.

The above description of the disclosed embodiments will enable those skilled in the art to make or use various modifications to these embodiments of the application. It will be apparent to those skilled in the art that the general principles defined herein It can be implemented in other embodiments without departing from the spirit or scope of the application. Therefore, the present application will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. A method for obtaining EGR flow, comprising: The exhaust pipe pressure obtained by the exhaust pressure sensor of the EGR system; Using the exhaust pipe pressure, fuel injection quantity and engine speed to obtain exhaust pulse pressure; Obtaining the inlet pulse pressure of the Venturi flowmeter by using the exhaust pulse pressure, the inlet temperature of the EGR cooler and the inlet temperature of the EGR valve; The exhaust gas flow rate is obtained according to the inlet pulse pressure of the Venturi flowmeter. 2. The method according to claim 1, characterized in that said using said exhaust pipe pressure, fuel injection quantity and engine speed to obtain exhaust pulse pressure specifically comprises: Use the engine speed and fuel injection volume as the X-axis and Y-axis of Map respectively; Obtaining a pulse pressure peak value and a pulse pressure trough value based on the Map and the exhaust pipe pressure; The exhaust pulse pressure is obtained by using the pulse pressure peak value and the pulse pressure valley value. 3. The method according to claim 1, wherein said utilizing said exhaust pulse pressure, EGR cooler inlet temperature and EGR valve inlet temperature to obtain the inlet pulse pressure of Venturi flowmeter, specifically comprises: Use the exhaust gas flow rate and the EGR cooler inlet temperature as the horizontal axis and the vertical axis to calibrate the EGR cooler differential pressure Map; use the exhaust gas flow rate and the EGR valve inlet temperature as the horizontal axis and the vertical axis to calibrate the EGR valve differential pressure Map; The inlet pulse pressure of the Venturi flowmeter is obtained according to the EGR cooler pressure difference Map, the EGR valve pressure difference Map and the exhaust pulse pressure. 4. The method according to claim 3, wherein the inlet pulse pressure of the Venturi flowmeter is obtained according to the EGR cooler differential pressure Map, the EGR valve differential pressure Map and the exhaust pulse pressure , including: According to the pulse pressure trough value in the exhaust pulse pressure, the EGR cooler pressure difference Map and the EGR valve pressure difference Map to obtain the Venturi inlet pressure trough value; according to the pulse pressure peak in the exhaust pulse pressure numerical value, the EGR cooler pressure difference Map and the EGR valve pressure difference Map to obtain the venturi inlet pressure peak value; The inlet pulse pressure of the Venturi flowmeter is obtained according to the trough value of the Venturi inlet pressure and the peak value of the Venturi inlet pressure. 5. The method according to claim 1, wherein said obtaining the exhaust gas flow according to the inlet pulse pressure of the Venturi flowmeter specifically comprises: The exhaust gas flow rate is obtained according to the inlet pulse pressure of the Venturi flowmeter, the inlet pipe pressure, the exhaust gas density, the Reynolds number and the Venturi flow coefficient. 6. A device for acquiring EGR flow, comprising: an exhaust pipe pressure acquisition unit, used to obtain the exhaust pipe pressure from the exhaust pressure sensor of the EGR system; an exhaust pulse pressure obtaining unit, configured to obtain the exhaust pulse pressure by using the exhaust pipe pressure, fuel injection quantity and engine speed; The inlet pulse pressure obtaining unit is used to obtain the inlet pulse pressure of the Venturi flowmeter by using the exhaust pulse pressure, the inlet temperature of the EGR cooler and the inlet temperature of the EGR valve; The exhaust gas flow obtaining unit is used to obtain the exhaust gas flow according to the inlet pulse pressure of the Venturi flowmeter. 7. The device according to claim 6, wherein the exhaust pulse pressure obtaining unit is specifically used to use the engine speed and the fuel injection quantity as the X-axis and the Y-axis of Map respectively; based on the Map and the The pulse pressure peak value and the pulse pressure trough value are obtained according to the exhaust pipe pressure; the exhaust pulse pressure is obtained by using the pulse pressure peak value and the pulse pressure trough value. 8. The device according to claim 6, wherein the inlet pulse pressure obtaining unit is specifically used to calibrate the EGR cooler pressure difference Map using the exhaust gas flow rate and the EGR cooler inlet temperature as the horizontal axis and the vertical axis respectively; The exhaust gas flow rate and the EGR valve inlet temperature are respectively used as the horizontal axis and the vertical axis to calibrate the EGR valve pressure difference Map; according to the EGR cooler pressure difference Map, the EGR valve pressure difference Map and the exhaust pulse pressure, the Venturi flow rate is obtained The inlet pulse pressure of the gauge. 9. The device according to claim 8, characterized in that the inlet pulse pressure obtaining unit obtains Venturi based on the EGR cooler pressure difference Map, the EGR valve pressure difference Map and the exhaust pulse pressure The inlet pulse pressure of the flowmeter specifically includes: obtaining the trough value of the Venturi inlet pressure according to the pulse pressure trough value in the exhaust pulse pressure, the EGR cooler pressure difference Map and the EGR valve pressure difference Map; The pulse pressure peak value in the exhaust pulse pressure, the EGR cooler pressure difference Map and the EGR valve pressure difference Map obtain the Venturi inlet pressure peak value; The inlet pulse pressure of the Venturi flowmeter is obtained according to the trough value of the Venturi inlet pressure and the peak value of the Venturi inlet pressure. 10. The device according to claim 6, characterized in that the exhaust gas flow obtaining unit is specifically used to calculate the inlet pulse pressure, intake pipe pressure, exhaust gas density, Reynolds number and Venturi flow rate of the Venturi flowmeter coefficient to obtain the exhaust gas flow.

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