CN115288865B - EGR flow obtaining method and device - Google Patents

Abstract

This application discloses a method and device for obtaining EGR flow. The method includes: using the exhaust pipe pressure obtained by the exhaust pressure sensor of the EGR system; using the exhaust pipe pressure, fuel injection volume and engine speed to obtain the exhaust pulse pressure ; Use the exhaust pulse pressure, EGR cooler inlet temperature and EGR valve inlet temperature to obtain the inlet pulse pressure of the Venturi flow meter; obtain the exhaust gas flow based on the inlet pulse pressure of the Venturi flow meter. The technical solution provided by this application eliminates the need for a Venturi differential pressure sensor and saves costs. Moreover, by calculating the exhaust pulse pressure, this application can fully consider the flow direction of the exhaust gas, deduct the reverse flow of the exhaust gas, and then more accurately obtain the forward flow of the exhaust gas flow, thereby accurately controlling the exhaust gas emission according to the exhaust gas flow, thereby avoiding Exhaust emissions exceed standards.

Description

A method and device for obtaining EGR flow

Technical field

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

Background technique

Exhaust gas recirculation (EGR, Exhaust Gas Recirculation) engines use Venturi flowmeters to test data. Currently, the pressure at the inlet and outlet of the Venturi flowmeter is obtained by a differential pressure sensor. However, in some cases, the differential pressure sensor will experience irregular sensor drift, which will cause the calculated exhaust gas flow to be inaccurate. When the exhaust gas flow calculation is inaccurate, it will cause the NOx control of the exhaust emission system to be inaccurate, thus Causes fuel consumption to worsen.

Contents of the invention

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

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

This application provides a method for obtaining EGR traffic, including:

Exhaust pipe pressure obtained using the exhaust pressure sensor of the EGR system;

The exhaust pipe pressure, fuel injection volume and engine speed are used to obtain the exhaust pulse pressure;

Using the exhaust pulse pressure, the EGR cooler inlet temperature and the EGR valve inlet temperature to obtain the inlet pulse pressure of the Venturi flow meter;

The exhaust gas flow rate is obtained based on the inlet pulse pressure of the Venturi flowmeter.

Preferably, the exhaust pipe pressure, fuel injection volume and engine speed are used to obtain the exhaust pulse pressure, specifically including:

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

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

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

Preferably, the use of the exhaust pulse pressure, the EGR cooler inlet temperature and the EGR valve inlet temperature to obtain the inlet pulse pressure of the Venturi flow meter specifically includes:

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

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

Preferably, obtaining the inlet pulse pressure of the Venturi flow meter based on the EGR cooler pressure difference Map, the EGR valve pressure difference Map and the exhaust pulse pressure specifically includes:

The Venturi inlet pressure trough value is obtained 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; according to the pulse pressure peak value in the exhaust pulse pressure The Venturi inlet pressure peak value is obtained from the numerical value, the EGR cooler pressure difference Map and the EGR valve pressure difference Map;

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

Preferably, the exhaust gas flow is obtained based on the inlet pulse pressure of the Venturi flowmeter, specifically including:

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

This application provides a device for obtaining EGR traffic, including:

The exhaust pipe pressure acquisition unit is used to obtain the exhaust pipe pressure using the exhaust pressure sensor of the EGR system;

An exhaust pulse pressure obtaining unit used to obtain the exhaust pulse pressure using the exhaust pipe pressure, fuel injection amount and engine speed;

An inlet pulse pressure acquisition unit, used to obtain the inlet pulse pressure of the Venturi flow meter using the exhaust pulse pressure, the EGR cooler inlet temperature and the EGR valve inlet temperature;

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

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

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

Preferably, the inlet pulse pressure obtaining unit obtains the inlet pulse pressure of the Venturi flow meter according to the EGR cooler pressure difference Map, the EGR valve pressure difference Map and the exhaust pulse pressure, specifically including: according to the The venturi inlet pressure trough value is obtained from the pulse pressure trough value in the exhaust pulse pressure, the EGR cooler pressure difference Map and the EGR valve pressure difference Map; 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 Venturi inlet pressure peak value;

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

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

It can be seen from the above technical solutions that this application has the following beneficial effects:

The EGR flow acquisition method provided by this application eliminates the need for a Venturi differential pressure sensor and saves costs. Moreover, by calculating the exhaust pulse pressure, this application can fully consider the flow direction of the exhaust gas, deduct the reverse flow of the exhaust gas, and then more accurately obtain the forward flow of the exhaust gas flow, thereby accurately controlling the exhaust gas emission according to the exhaust gas flow, thereby avoiding Exhaust emissions exceed standards.

Description of the drawings

In order to more clearly explain the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the 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 exerting creative efforts.

Figure 1 is a schematic diagram of an EGR system provided by this application;

Figure 2 is a flow chart of a method for obtaining EGR traffic provided by this application;

Figure 3 is a schematic diagram of an exhaust pulse pressure and a Venturi inlet pulse pressure provided by this application;

Figure 4 is an architectural diagram for obtaining exhaust pulse pressure provided by this application;

Figure 5 is a trough architecture diagram for obtaining the Venturi inlet pulse pressure provided by this application;

Figure 6 is a wave peak structure diagram for obtaining the Venturi inlet pulse pressure provided by this application;

Figure 7 is an architecture diagram for obtaining exhaust gas flow provided by this application;

Figure 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 by the embodiments of the present application, before introducing the methods provided by the embodiments of the present application, the application scenarios of the solutions provided by the embodiments of the present application are first introduced.

Refer to Figure 1, which is a schematic diagram of an EGR system provided by this application.

As can be seen from Figure 1, an exhaust pressure sensor 10 (referred to as exhaust pipe pressure P) is installed on the exhaust pipe. Along the direction of exhaust gas flow, it is connected to the EGR cooler 20 (which can be equipped with a one-way valve at the back). No one-way valve, depends on the system)), EGR cooler rear 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.

Among them, Cyl1-Cyl6 are the six cylinders of the engine.

Since during the exhaust gas discharge process, the exhaust gas may have backflow, that is, backflow, sometimes it may flow from top to bottom, and sometimes it may flow from bottom to upward. Therefore, in order to accurately obtain the flow rate of the exhaust gas, this application needs to identify the flow direction of the exhaust gas. , only by making a difference in the two directions can the accurate exhaust gas flow rate be obtained. The technical solution provided by this application will be described in detail below with reference to the accompanying drawings. In addition, in order to save costs, this application omits the differential pressure sensor of the Venturi, and instead obtains the pressure difference between the inlet and outlet of the Venturi through calculation. Since the cost of the differential pressure sensor is relatively high, the technical solution provided by this application can also be used 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 modes.

Refer to Figure 2, which is a flow chart of a method for obtaining EGR traffic provided by this application.

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

S201: Exhaust pipe pressure obtained 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.

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

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

Since the exhaust pulse pressure is in the form of a pulse, there are peaks and troughs, and the peaks and troughs of the exhaust pulse pressure need to be obtained based on the fuel injection amount and engine speed.

Since there is backflow in the exhaust, the exhaust pulse pressure can represent the flow direction of the exhaust 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 forward, that is, the exhaust gas flows from It flows upward and downward; on the contrary, when the exhaust pulse pressure is less than the intake pressure, it means that the exhaust gas flow direction is reverse, that is, the exhaust gas flows from bottom to upward. If the forward flow of exhaust gas is a positive number and the reverse flow is a negative number, the total flow should be the sum of the positive and negative flows. Obviously, after this application considers the direction of exhaust gas flow, the exhaust gas flow rate can be obtained more accurately, and then the exhaust gas emission can be controlled to avoid excessive exhaust gas emissions.

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

Since there are EGR cooler, EGR cooled temperature sensor and EGR valve between the exhaust pipe and the inlet of the Venturi flow meter, the inlet pulse pressure of the Venturi flow meter needs to be based on the exhaust pulse pressure and the EGR cooler inlet temperature. 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 pulses, becoming the inlet pulse pressure of the Venturi flowmeter.

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

Since the inlet pipe pressure becomes the outlet pressure of the Venturi flow meter, the exhaust gas flow rate can be obtained based on the inlet pipe pressure and the inlet pulse pressure of the Venturi flow meter as well as the preset coefficient and exhaust gas density.

The EGR flow acquisition method provided by this application eliminates the need for a Venturi differential pressure sensor and saves costs. Moreover, by calculating the exhaust pulse pressure, this application can fully consider the flow direction of the exhaust gas, deduct the reverse flow of the exhaust gas, and then more accurately obtain the forward flow of the exhaust gas flow, thereby accurately controlling the exhaust gas emission according to the exhaust gas flow, thereby avoiding Exhaust emissions exceed standards.

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

Refer to Figure 3, which is a schematic diagram of exhaust pulse pressure and Venturi inlet pulse pressure provided by this 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. It should be understood that these two sine waves are obtained by calculations in this application and cannot be directly used by the sensor. measured. In addition, the pulse pressure peak value and pulse pressure trough value corresponding to the exhaust pulse pressure are also calibrated in the figure. Among them, the intake pressure P_in and the exhaust pipe pressure P can be directly measured by sensors.

The exhaust pipe pressure, fuel injection volume and engine speed are used to obtain the exhaust pulse pressure, which specifically includes:

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

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

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

Refer to Figure 4, which is an architecture diagram for obtaining exhaust pulse pressure provided by this application.

Since the exhaust pressure exists in the form of pulsations, the exhaust pressure will have a great impact on the accuracy of the entire exhaust gas flow. Therefore, the average pressure P (exhaust pipe pressure) during this time needs to be corrected to capture the impact of pulses 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 trough coefficient C_Trough are calibrated into two Maps (Peak_Map and Tough_Map) respectively. The X and Y axes of the Map are the engine speed and the fuel injection amount respectively. Based on the exhaust pipe pressure P tested by the calibrated Map and 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. At the same time, 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), and the firing interval Angel_Firing is 720/Cyl_num degrees. According to the above parameters, the function of the exhaust pulse pressure sine wave can be obtained.

Along the flow direction of the exhaust gas, calibrate the EGR cooler pressure difference Map (the horizontal axis is the exhaust gas flow, the vertical axis is the temperature after the EGR cooler) and the EGR valve pressure difference Map (the horizontal axis is the exhaust gas flow, and the vertical axis is EGR valve inlet temperature), based on Map, the pressure difference of key components can be quickly solved, thereby solving the Venturi inlet pressure peak value and inlet pressure trough value. Combined with the opening duration and firing interval, the Venturi inlet pulse pressure can be obtained .

See Figure 5, which is a trough structure diagram for obtaining the Venturi inlet pulse pressure provided by this application.

The exhaust pulse pressure, EGR cooler inlet temperature and EGR valve inlet temperature are used to obtain the inlet pulse pressure of the Venturi flow meter, which specifically includes:

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

The inlet pulse pressure of the Venturi flow meter 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 flow meter based on the exhaust pipe pressure, intake pressure and exhaust pulse pressure.

First, Figure 5 illustrates the process of the Venturi inlet pressure trough value P_low_venturi. 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, the Venturi inlet pressure trough value P_low_venturi is obtained based on the pulse pressure trough value P_tough, coefficient P_diff_egrc and coefficient P_diff_value of the exhaust pressure.

See Figure 6, which is a wave peak structure diagram for obtaining the Venturi inlet pulse pressure provided by this application.

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

Comparing Figure 6 and Figure 5, the difference is that in Figure 6, the venturi inlet pressure peak value P_high_ven is obtained using the pulse pressure peak value P_peak, coefficient P_diff_egrc and coefficient P_diff_value of the exhaust pressure. Others are the same as Figure 5 and will not be repeated here. Repeat.

Refer to Figure 7, which is an architecture diagram for obtaining exhaust gas flow provided by this 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 flow meter can be obtained. If the system has a one-way valve, the logic for calculating the exhaust gas flow only applies to areas where the pressure difference value is greater than 0. Perform integration. If the system does not have a one-way valve, it needs to be integrated throughout the cycle. According to the average value P1 of the venturi flowmeter inlet and intake pipe pressure, the temperature T after the EGR cooler, and the gas constant R, the density of the exhaust gas ρ = P1/(R*T) can be obtained. According to the assumed exhaust gas flow m, Venturi The geometric parameter d (constant value) of the design roar port and the exhaust gas density ρ can be used to obtain the Reynolds number Re of the air flow inside the Venturi. Based on the relationship between this Reynolds number and the Venturi flow coefficient, the flow rate of the Venturi flowmeter under this working condition can be obtained. The coefficient Cd, based on the exhaust gas density, the pressure difference before and after Venturi, the flow coefficient, and the exhaust gas incompressibility correction coefficient can be integrated in real time to obtain the exhaust gas flow in the entire working cycle. This exhaust gas flow is compared with the assumed exhaust gas flow in real time, and both are ultimately required. If the error rate is less than 0.05%, it is considered that the calculation has converged, and the exhaust gas flow value obtained at this time is an accurate value.

Since the technical solution provided by this application can accurately obtain the exhaust gas flow rate, the exhaust gas emission can be controlled based on the accurate exhaust gas flow rate, thereby improving the exhaust gas emission quality and avoiding excessive exhaust gas emissions.

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

Refer to Figure 8, which is a schematic diagram of an EGR flow acquisition device provided by an embodiment of the present application.

The device for obtaining EGR traffic provided in this embodiment includes:

The exhaust pipe pressure obtaining unit 801 is used to obtain the exhaust pipe pressure 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 using the exhaust pipe pressure, fuel injection amount and engine speed;

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

Since the exhaust pulse pressure is in the form of a pulse, there are peaks and troughs, and the peaks and troughs of the exhaust pulse pressure need to be obtained based on the fuel injection amount and engine speed.

Since there is backflow in the exhaust, the exhaust pulse pressure can represent the flow direction of the exhaust 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 forward, that is, the exhaust gas flows from It flows upward and downward; on the contrary, when the exhaust pulse pressure is less than the intake pressure, it means that the exhaust gas flow direction is reverse, that is, the exhaust gas flows from bottom to upward. If the forward flow of exhaust gas is a positive number and the reverse flow is a negative number, the total flow should be the sum of the positive and negative flows. Obviously, after this application considers the direction of exhaust gas flow, the exhaust gas flow rate can be obtained more accurately, and then the exhaust gas emission can be controlled to avoid excessive exhaust gas emissions.

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

Since there are EGR cooler, EGR cooled temperature sensor and EGR valve between the exhaust pipe and the inlet of the Venturi flow meter, the inlet pulse pressure of the Venturi flow meter needs to be based on the exhaust pulse pressure and the EGR cooler inlet temperature. 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 pulses, becoming the inlet pulse pressure of the Venturi flowmeter.

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

Since the inlet pipe pressure becomes the outlet pressure of the Venturi flow meter, the exhaust gas flow rate can be obtained based on the inlet pipe pressure and the inlet pulse pressure of the Venturi flow meter as well as the preset coefficient and exhaust gas density.

The EGR flow acquisition device provided by this application eliminates the need for a Venturi differential pressure sensor and saves costs. Moreover, by calculating the exhaust pulse pressure, this application can fully consider the flow direction of the exhaust gas, deduct the reverse flow of the exhaust gas, and then more accurately obtain the forward flow of the exhaust gas flow, thereby accurately controlling the exhaust gas emission according to the exhaust gas flow, thereby avoiding Exhaust emissions exceed standards.

The exhaust pulse pressure obtaining unit is specifically used to use the engine speed and the fuel injection amount as the X-axis and Y-axis of the Map respectively; obtain the pulse pressure peak value and the pulse pressure trough value based on the Map and the exhaust pipe pressure; using The pulse pressure peak value and the pulse pressure trough 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 and the EGR cooler inlet temperature as the horizontal axis and the vertical axis respectively; using the exhaust gas flow and the EGR valve inlet temperature as the horizontal axis and the vertical axis respectively to calibrate the EGR Valve pressure difference Map; obtain the inlet pulse pressure of the Venturi flow meter 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 flow meter 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 venturi inlet pressure trough value is obtained 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; 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 Venturi inlet pressure peak value;

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

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

From the description of the above embodiments, 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 the necessary general hardware platform. Based on this understanding, the technical solution of the present application can be embodied in the form of a software product in essence or that contributes to the existing technology. The computer software product can be stored in a storage medium, such as ROM/RAM, disk , optical disk, etc., including a number of instructions to cause a computer device (which can be a personal computer, a server, or a network communication device such as a media gateway, etc.) to execute the various embodiments or certain parts of the embodiments of this application. method.

It should be noted that each embodiment in this specification is described in a progressive manner, and each embodiment focuses on its differences from other embodiments. The same and similar parts between the various embodiments 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. For relevant details, please refer to the description of the system part.

It should also be noted that, as used herein, the terms "comprises," "comprises," or any other variation thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements , but also includes other elements not expressly listed or inherent in such process, method, article or equipment. Without further limitation, an element defined by the statement "comprises a..." does not exclude the presence of additional identical elements in a process, method, article, or apparatus that includes the stated element.

The above description of the disclosed embodiments will make it apparent to those skilled in the art that various modifications to these embodiments can be made or used herein, in accordance with the general principles defined herein. This may be implemented in other embodiments without departing from the spirit or scope of the application. Therefore, the present application is not to 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 (6)

1. An EGR flow rate obtaining method is characterized by comprising the following steps:

exhaust pipe pressure obtained by an exhaust gas pressure sensor of the EGR system;

obtaining exhaust pulse pressure by using the exhaust pipe pressure, the fuel injection quantity and the engine rotating speed;

obtaining an inlet pulse pressure of the venturi meter by using the exhaust pulse pressure, the EGR cooler inlet temperature and the EGR valve inlet temperature;

obtaining exhaust gas flow according to inlet pulse pressure of the venturi flowmeter;

the method for 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 comprises the following steps:

calibrating an EGR cooler differential pressure Map by taking the exhaust gas flow and the EGR cooler inlet temperature as a horizontal axis and a vertical axis respectively; the exhaust gas flow and the EGR valve inlet temperature are respectively used as a horizontal axis and a vertical axis to calibrate an EGR valve pressure difference Map;

obtaining inlet pulse pressure of a venturi flowmeter according to the EGR cooler pressure difference Map, the EGR valve pressure difference Map and the exhaust pulse pressure;

the method for obtaining the flow of the waste gas according to the inlet pulse pressure of the venturi flowmeter specifically comprises the following steps:

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

2. The method according to claim 1, wherein said using said exhaust pipe pressure, fuel injection amount and engine speed to obtain exhaust pulse pressure comprises:

taking the engine speed and the oil injection quantity as an X axis and a Y axis of Map respectively;

acquiring a pulse pressure crest value and a pulse pressure trough value based on the Map and the exhaust pipe pressure;

and obtaining the exhaust pulse pressure by using the pulse pressure crest value and the pulse pressure trough value.

3. The method according to claim 1, wherein said deriving an inlet pulse pressure of a venturi meter from said EGR cooler differential pressure Map, said EGR valve differential pressure Map and said exhaust pulse pressure, comprises in particular:

obtaining a Venturi inlet pressure trough value 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; obtaining a venturi inlet pressure peak value according to a pulse pressure peak value in the exhaust pulse pressure, the EGR cooler differential pressure Map and the EGR valve differential pressure Map;

and obtaining the inlet pulse pressure of the venturi flowmeter according to the venturi inlet pressure trough value and the venturi inlet pressure crest value.

4. An EGR flow rate acquisition device, characterized by comprising:

an exhaust pipe pressure obtaining unit for obtaining an exhaust pipe pressure using an exhaust gas pressure sensor of the EGR system;

an exhaust pulse pressure obtaining unit for obtaining an exhaust pulse pressure using the exhaust pipe pressure, the fuel injection amount, and the engine speed;

an inlet pulse pressure obtaining unit for obtaining an inlet pulse pressure of the venturi meter using the exhaust pulse pressure, the EGR cooler inlet temperature, and the EGR valve inlet temperature;

an exhaust gas flow obtaining unit for obtaining an exhaust gas flow from an inlet pulse pressure of the venturi meter;

the inlet pulse pressure obtaining unit is specifically used for:

calibrating an EGR cooler differential pressure Map by taking the exhaust gas flow and the EGR cooler inlet temperature as a horizontal axis and a vertical axis respectively; the exhaust gas flow and the EGR valve inlet temperature are respectively used as a horizontal axis and a vertical axis to calibrate an EGR valve pressure difference Map; obtaining inlet pulse pressure of a venturi flowmeter according to the EGR cooler pressure difference Map, the EGR valve pressure difference Map and the exhaust pulse pressure;

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

5. The apparatus according to claim 4, wherein the exhaust pulse pressure obtaining unit is specifically configured to use an engine speed and an injection amount as an X-axis and a Y-axis of Map, respectively; acquiring a pulse pressure crest value and a pulse pressure trough value based on the Map and the exhaust pipe pressure; and obtaining the exhaust pulse pressure by using the pulse pressure crest value and the pulse pressure trough value.

6. The apparatus according to claim 4, wherein the inlet pulse pressure obtaining unit obtains an inlet pulse pressure of a venturi flow meter from the EGR cooler differential pressure Map, the EGR valve differential pressure Map, and the exhaust pulse pressure, specifically comprising: obtaining a Venturi inlet pressure trough value 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; obtaining a venturi inlet pressure peak value according to a pulse pressure peak value in the exhaust pulse pressure, the EGR cooler differential pressure Map and the EGR valve differential pressure Map;

and obtaining the inlet pulse pressure of the venturi flowmeter according to the venturi inlet pressure trough value and the venturi inlet pressure crest value.