CN113074051B

CN113074051B - EGR valve exhaust gas flow value calculation method and system and engine parameter adjustment method

Info

Publication number: CN113074051B
Application number: CN202010007843.XA
Authority: CN
Inventors: 何宇; 连学通; 苏庆鹏
Original assignee: Guangzhou Automobile Group Co Ltd
Current assignee: Guangzhou Automobile Group Co Ltd
Priority date: 2020-01-06
Filing date: 2020-01-06
Publication date: 2022-11-25
Anticipated expiration: 2040-01-06
Also published as: CN113074051A

Abstract

The invention discloses a method and a system for calculating an exhaust gas flow value of an EGR valve, which comprises the following steps that a, a preset initial pressure value is used as a pressure value after the EGR valve; b, calculating an exhaust gas flow value of the EGR valve according to the pressure value after the EGR valve; c, calculating a pressure value after the throttle valve according to the waste gas flow value of the EGR valve and the total air intake value input into the engine cylinder; d, judging whether the absolute value of the pressure value obtained by subtracting the EGR valve from the pressure value after the throttling valve is smaller than a preset value or not, if not, taking the pressure value after the throttling valve as the new pressure value after the EGR valve, and continuing to execute the step b; otherwise, taking the exhaust gas flow value of the EGR valve in the step b as the current exhaust gas flow value of the EGR valve. Therefore, the pressure value behind the throttle valve is used as the input quantity and iteration is carried out, so that the accurate calculation of the exhaust gas flow of the EGR valve is realized only through a commonly used measuring device on the existing engine under the condition that a sensor is not additionally added.

Description

EGR valve exhaust gas flow value calculation method and system and engine parameter adjustment method

Technical Field

The invention relates to the technical field of engine control, in particular to a method and a system for calculating an exhaust gas flow value of an EGR valve and an engine parameter adjusting method.

Background

With the continuous rise of fuel oil prices and the gradual and severe greenhouse effect, the control on the fuel oil consumption of automobiles is more and more strict. At present, the intake pressure of the engine is mostly improved through a supercharging technology, so that the power density of the engine is improved, the volume of the engine is reduced, the power output reaches or even exceeds that of an original gasoline engine, and the fuel efficiency of the engine is further improved. However, this also entails problems such as increased combustion temperature, increased thermal load, increased tendency to knock, and increased NOx emissions. In order to solve the problem, the opening of a throttle valve is often increased by introducing EGR (Exhaust Gas recirculation) into the gasoline engine, and the pumping loss is effectively reduced by reasonably controlling the flow of the EGR, so that the fuel consumption is reduced.

However, in the engine control, the EGR flow rate is calculated inaccurately because the EGR arrangement type pipeline is longer and delays the intake air, and on the other hand, under the steady-state condition of the engine, the differential pressure before and after the EGR valve is too small, the control of the EGR flow rate is interfered, so that how to accurately calculate the exhaust gas flow rate value of the EGR valve is particularly critical to the efficient application of the EGR.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a method and a system for calculating an exhaust gas flow value of an EGR valve, which can perform iteration by using a pressure value behind a throttle valve as an input quantity, and improve the accuracy of the exhaust gas flow value of the EGR valve.

In order to solve the above technical problem, a first aspect of the present invention discloses a method for calculating an exhaust gas flow value of an EGR valve, which is applied to an exhaust gas recirculation system, the exhaust gas recirculation system includes a throttle valve and the EGR valve, an outlet pipe of the throttle valve is communicated with an outlet pipe of the EGR valve, and air output by the throttle valve is mixed with exhaust gas output by the EGR valve and then input into an engine cylinder, the method includes:

a, taking a preset initial pressure value as a pressure value after an EGR valve;

b, calculating an exhaust gas flow value of the EGR valve according to the pressure value after the EGR valve;

c, calculating a pressure value after the throttle valve according to the waste gas flow value of the EGR valve and the total air intake value input into the cylinder of the engine;

d, judging whether the absolute value of the pressure value obtained by subtracting the EGR valve from the pressure value after the throttling valve is smaller than a preset value or not, if not, taking the pressure value after the throttling valve as the new pressure value after the EGR valve, and continuing to execute the step b; otherwise, taking the exhaust gas flow value of the EGR valve in the step b as the current exhaust gas flow value of the EGR valve.

As an alternative embodiment, taking the preset initial pressure value as the pressure value after the EGR valve includes:

and collecting an initial pressure value after the throttle valve, and delaying for a preset time length to take the initial pressure value as a pressure value after the EGR valve.

As an alternative embodiment, calculating the exhaust gas flow rate value of the EGR valve according to the pressure value after the EGR valve includes:

acquiring a pressure difference between the front and the back of an EGR valve by using a pressure difference sensor, and determining a pressure value before the EGR valve according to the pressure difference between the front and the back of the EGR valve and the pressure value after the EGR valve;

collecting an exhaust gas temperature value of an exhaust gas system pipeline in front of an EGR valve by using a temperature sensor;

calculating an exhaust gas flow value of the EGR valve according to the following formula:

q' is an exhaust gas flow value of the EGR valve, A is a preset flow area of the EGR valve, delta P is a pressure difference between the front and the rear of the EGR valve, K is a flow calculation correction coefficient, and rho is an exhaust gas density;

pin is the pressure value before the EGR valve, tin is the exhaust gas temperature value of the exhaust gas system pipeline before the EGR valve, and R is a thermodynamic gas constant.

As an alternative embodiment, calculating the pressure value after the throttle valve according to the exhaust gas flow value of the EGR valve and the total intake air value input to the engine cylinder comprises:

collecting a total air intake value input into an engine cylinder;

subtracting the exhaust gas flow value of the EGR valve from the total air intake value input into the engine cylinder to obtain an air flow value;

and calculating the pressure value after the throttle valve according to the air flow value, the pressure value before the throttle valve, the current ambient temperature value, the current ambient pressure value and the throttle valve opening.

As an optional implementation manner, calculating the pressure value after the throttle valve according to the airflow value, the pressure value before the throttle valve, the current ambient temperature value, the current ambient pressure value, and the throttle opening degree includes:

collecting the differential pressure before and after the throttle valve with the current throttle valve opening by using a differential pressure sensor;

collecting a current ambient pressure value by using a pressure sensor;

acquiring a current environment temperature value by using a temperature sensor;

calculating the post-throttle pressure value for the current throttle opening according to:

wherein Pout is a pressure value after the throttle valve, pin is a pressure value before the throttle valve, Q is an air flow value, ρ is an air density, A is a preset flow area of the throttle valve, K is a flow calculation correction coefficient, wherein,

pin is the pressure value before the throttle valve, tin is the current environment temperature value, and R is the thermodynamic gas constant.

As an optional implementation manner, after determining whether an absolute value of the pressure value after the throttle valve minus the pressure value after the EGR valve is smaller than a preset value, the method further includes:

and if not, calculating the exhaust gas flow value of the EGR valve according to the pressure value after the EGR valve as the current pressure value after the throttle valve.

In a second aspect of the invention, a method of adjusting an engine parameter is disclosed, the method comprising:

obtaining a current exhaust gas flow value of the EGR valve by using the method for calculating the exhaust gas flow value of the EGR valve in the first aspect of the invention;

adjusting engine parameters according to the current exhaust gas flow of the EGR valve;

wherein the engine parameter comprises at least one of EGR rate, engine torque, engine fuel injection quantity, and engine firing angle.

The third aspect of the present invention discloses a system for calculating an exhaust gas flow value of an EGR valve, the system is applied to an exhaust gas recirculation system, the exhaust gas recirculation system comprises a throttle valve and an EGR valve, an air outlet pipeline of the throttle valve is communicated with an air outlet pipeline of the EGR valve, air output by the throttle valve is mixed with exhaust gas output by the EGR valve and then input into an engine cylinder, and the system comprises:

the collecting module is used for taking a preset initial pressure value as a pressure value after the EGR valve;

the first calculation module is used for calculating an exhaust gas flow value of the EGR valve according to the pressure value after the EGR valve;

the second calculation module is used for calculating the pressure value after the throttle valve according to the exhaust gas flow value of the EGR valve and the total air intake value input into an engine cylinder;

the iteration module is used for judging that the absolute value of the pressure value after the throttling valve minus the pressure value after the EGR valve in the first calculation module is smaller than a preset value, if not, taking the pressure value after the throttling valve as a new pressure value after the EGR valve, and continuously executing the first calculation module; and if not, taking the exhaust gas flow value of the EGR valve in the first calculation module as the current exhaust gas flow value of the EGR valve.

As an optional implementation, the first calculation module includes: the first acquisition unit is used for acquiring the pressure difference before and after the EGR valve through a pressure difference sensor and acquiring the pressure value before the EGR valve through a pressure sensor;

the second acquisition unit is used for acquiring the exhaust gas temperature value of the exhaust system pipeline in front of the EGR valve through the temperature sensor;

a calculation unit for calculating an exhaust gas flow rate value of the EGR valve according to:

pin is the pressure value before the EGR valve, tin is the exhaust gas temperature value of the exhaust system pipeline before the EGR valve, and R is the thermodynamic gas constant.

As an optional implementation manner, the iteration module is further configured to, when it is determined whether an absolute value obtained by subtracting the pressure value after the EGR valve in the first calculation module from the pressure value after the throttle valve is smaller than a preset value is negative, take the exhaust gas flow value of the EGR valve calculated according to the pressure value after the EGR valve as the current pressure value after the throttle valve.

In a fourth aspect of the present invention, there is disclosed an apparatus for adjusting engine parameters, the apparatus comprising:

a memory storing executable program code;

a processor coupled with the memory;

the processor calls the executable program code stored in the memory to execute the method for adjusting the engine parameter according to the second aspect of the present invention.

A fifth aspect of the present invention discloses a computer storage medium having stored thereon computer instructions for executing the method of calculating an EGR valve exhaust gas flow value according to any of the first aspects of the present invention when invoked.

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

according to the invention, parameters such as pressure values and temperature values of the throttle valve and the EGR valve can be acquired by using a differential pressure sensor and a temperature sensor which are commonly used on the existing engine to carry out iterative calculation, the accurate calculation of the EGR exhaust gas flow can be realized by the iterative calculation mode, and the EGR exhaust gas flow with higher accuracy is used for controlling engine parameters such as the EGR rate, the engine torque, the fuel injection quantity, the ignition angle and the like, so that the fuel economy of the engine is improved, the exhaust gas emission can be reduced, and the occurrence of knocking is inhibited.

Drawings

FIG. 1 is a schematic flow chart illustrating a method for calculating an EGR valve exhaust gas flow value according to an embodiment of the present invention;

FIG. 2 is a schematic flow chart illustrating another method for calculating an exhaust gas flow rate of an EGR valve according to an embodiment of the present disclosure;

FIG. 3 is a schematic flow chart of a method for adjusting engine parameters according to an embodiment of the present disclosure;

FIG. 4 is a schematic diagram of a system for calculating an exhaust gas flow rate of an EGR valve according to an embodiment of the present disclosure;

FIG. 5 is a schematic structural diagram of an engine parameter adjusting device according to an embodiment of the present disclosure;

fig. 6 is a schematic structural diagram of an engine disclosed in the embodiment of the invention.

Detailed Description

For better understanding and implementation, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The terms "comprises," "comprising," and any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or modules is not necessarily limited to those steps or modules explicitly listed, but may include other steps or modules not expressly listed or inherent to such process, method, article, or apparatus.

The embodiment of the invention discloses a method and a device for calculating an exhaust gas flow value of an EGR valve, wherein the method and the device only use a differential pressure sensor, a temperature sensor and the like which are commonly used on the existing engine to acquire parameters such as pressure values, temperature values and the like of a throttle valve and the EGR valve to carry out iterative calculation, the accurate calculation of the exhaust gas flow of the EGR can be realized by the iterative calculation mode, and the EGR exhaust gas flow with higher accuracy is used for controlling engine parameters such as EGR rate, engine torque, fuel injection quantity, ignition angle and the like, so that the fuel economy of the engine is improved, the discharged exhaust gas can be reduced, and the occurrence of knocking is inhibited. The following are detailed descriptions.

With the continuous rise of fuel oil prices and the gradual and severe greenhouse effect, the control on the fuel oil consumption of automobiles is more and more strict. At present, small intensification has become a promising direction to improve engine fuel economy. The small-sized strengthening is realized by improving the air inlet pressure of the engine through a supercharging technology, improving the power density, reducing the volume of the engine and ensuring that the power output reaches or even exceeds the original engine on the whole. However, small intensification also brings about problems such as an increase in combustion temperature, an increase in heat load, an increase in the tendency to knock, and an increase in NOx emission. EGR has become an effective means for improving the fuel economy of gasoline engines, and the opening degree of a throttle valve can be increased by introducing EGR or excess air to the gasoline engine, so that the pumping loss is effectively reduced, and further, the fuel consumption is reduced. Further, the EGR technique can suppress occurrence of knocking because: on one hand, CO2 and H2O in the waste gas have higher specific heat ratio, and can absorb a large amount of heat in the compression and combustion processes to reduce the temperature in the cylinder, thereby reducing the spontaneous combustion tendency of the tail end mixed gas; on the other hand, the EGR dilutes combustible mixture gas, reduces collision probability of fuel molecules and oxygen molecules, and reduces reaction rate of the tail end mixture gas before flame. How to determine and adjust the mass flow of EGR is critical to the control of the EGR rate.

The calculation of the EGR flow is a key problem in air intake control, because in the engine control, the adjustment of parameters such as torque output by an engine, oil injection quantity, ignition angle, throttle opening and the like is based on accurate air intake quantity calculation, the EGR flow is reasonably controlled, and the pumping loss can be reduced. The EGR flow is calculated inaccurately because the EGR distribution type pipeline is longer and brings delay to air inlet, and on the other hand, the control of the EGR flow is interfered because the differential pressure before and after the EGR valve is too small under the steady state condition.

Exemplarily, as shown in fig. 6, fig. 6 is a schematic structural view of an engine according to an embodiment of the present invention. The engine includes: a throttle valve 1, an EGR valve 2 and engine cylinders 3. A valve opening sensor 11 is provided at the throttle valve 1, and a pressure sensor (not shown) is connected to the rear of the throttle valve 1. A differential pressure sensor 21 and a valve opening sensor 22 are provided at the EGR valve 2, and a temperature sensor 23 is provided between an intake port of the EGR valve 2 and an intercooler 24 of the EGR valve 2. An intake air flow sensor 31, a temperature sensor (not shown), and a pressure sensor (not shown) are provided at the intake port of the engine cylinder 3.

It should be noted that the present invention is not limited to the structure of the engine, and any engine that can use the exhaust gas recirculation system is within the protection scope of the present invention, and the exhaust gas recirculation system includes a throttle valve and an EGR valve, an outlet pipe of the throttle valve is communicated with an outlet pipe of the EGR valve, and air output from the throttle valve is mixed with exhaust gas output from the EGR valve and then input into an engine cylinder. The connection mode of mixing the air output by the throttle valve and the exhaust gas output by the EGR valve and inputting the mixture into the engine cylinder is not limited.

Example one

Referring to fig. 1, fig. 1 is a schematic flow chart illustrating a method for calculating an exhaust gas flow value of an EGR valve according to an embodiment of the present invention. The method described in fig. 1 may be applied to an exhaust gas recirculation system, in this embodiment, an exhaust gas recirculation system included in the exhaust gas recirculation system is taken as an example, and in other embodiments, the method may also be applied to a low-pressure exhaust gas recirculation system, a supercharged exhaust gas recirculation system, and the like, which are not limited herein. The exhaust gas recirculation system comprises a throttle valve and an EGR valve, wherein an air outlet pipeline of the throttle valve is communicated with an air outlet pipeline of the EGR valve, and air output by the throttle valve is mixed with exhaust gas output by the EGR valve and then input into an engine cylinder. The connection method for mixing the air output by the throttle valve and the exhaust gas output by the EGR valve and inputting the mixture into the engine cylinder is not limited, wherein both the EGR valve and the throttle valve can control the flow of the circulated gas through different valve openings, and as shown in fig. 1, the method for calculating the exhaust gas flow value of the EGR valve may include the following operations:

101. and taking the preset initial pressure value as the pressure value after the EGR valve.

Because the integral conception of the application is that the pressure value of the EGR valve is subjected to iteration operation, so that the calculation result is more accurate, an initial pressure value is firstly introduced to start the iteration operation, and for the convenience of subsequent calculation, the preset initial pressure value is recorded as P0-1/2dP and is used as the pressure value behind the EGR valve, wherein in the physical sense, P0 can be realized as the current atmospheric pressure value, and dP is the current differential pressure value. It should be noted that the preset initial pressure value is only manually selected to start the whole iteration process, and the specific value is not limited.

102. And calculating the exhaust gas flow value of the EGR valve according to the pressure value after the EGR valve.

First, in an exhaust gas recirculation system, a Control method is mainly implemented by an ECU (Electronic Control Unit, also called a "traveling computer" or an "on-board computer", etc., and is a microcomputer controller dedicated to an automobile in terms of usage), a pressure sensor (which is an internal structure already installed in an engine in an existing exhaust gas recirculation system and connected to the ECU) is connected behind a throttle valve, a differential pressure sensor and a valve opening sensor are provided at an EGR valve, and a temperature sensor and a pressure sensor are provided between an intake port of the EGR valve and an intercooler of the EGR valve. After the ECU receives a calculation instruction of the EGR valve exhaust gas flow value, the instruction can be set in an exhaust gas recirculation system according to the running state of an engine, and can also be initiated automatically according to the test requirement of a user.

Further, differential pressure sensors at the positions of the EGR valves are controlled by the ECU to acquire differential pressure before and after the EGR valves under different valve opening degrees, the differential pressure is recorded as dP, then according to the differential pressure dP before and after the EGR valves and the pressure value P0-1/2dP after the EGR valves, the pressure value before the EGR valves is recorded as P0+ dP, and the determined pressure value before the EGR valves is sent to the ECU.

And then, acquiring the exhaust gas temperature value of an exhaust gas system pipeline of the EGR valve in front of the EGR valve under different valve opening degrees by an ECU (electronic control Unit) based temperature sensor behind the EGR intercooler, recording the exhaust gas temperature value as T, and sending the exhaust gas temperature value of the exhaust gas system pipeline in front of the EGR valve to the ECU.

The temperature sensor and the differential pressure sensor are directed to the same EGR valve opening degree at the same time. The operation of acquiring the temperature sensor and the differential pressure sensor may be acquired together with the pressure value after the throttle valve in step 101, or may be acquired in a stepwise manner according to the operating state of the ECU, which is not limited herein.

And when the ECU receives the determined pressure value P0+ dp before the EGR valve and the exhaust gas temperature value T of the exhaust system pipeline before the EGR valve, calculating to obtain the exhaust gas flow value of the EGR valve.

In the present embodiment, the exhaust gas flow rate value of the EGR valve may be calculated in accordance with the bernoulli equation as follows;

further, the bernoulli equation is:

q' is an exhaust gas flow value of the EGR valve, A is a preset flow area of the EGR valve, the preset flow area is obtained through calculation according to an opening degree theory and is defined as a geometric definition, delta P is a pressure difference between the front portion and the rear portion of the EGR valve, K is a flow calculation correction coefficient, and rho is an exhaust gas density;

wherein Pin is a pressure value before the EGR valve, tin is an exhaust gas temperature value of an exhaust gas system pipeline before the EGR valve, and R is a thermodynamic gas constant.

Optionally, in order to obtain a more accurate exhaust gas flow value of the EGR valve, the exhaust gas density may be averaged for multiple times and then substituted into the bernoulli equation.

The present embodiment is not limited to other calculation methods for calculating the exhaust gas flow rate value of the EGR valve, such as the conventional flow rate distribution method.

103. And calculating the pressure value after the throttle valve according to the exhaust gas flow value of the EGR valve and the total air intake value input into the cylinder of the engine.

First, the total air intake value input to the engine cylinder is collected and designated as M. The total intake air quantity value input to the engine cylinder may be directly collected in the present embodiment based on an intake air flow sensor provided at the cylinder intake port.

Optionally, the total intake air amount of the engine cylinder may be obtained by performing a balance calculation on a balance between an intake pipe inflow air amount and an intake pipe outflow air amount by the ECU, specifically by configuring the ECU to: it is determined whether the engine stop position of the engine is within the valve overlap period, and when the engine stop position is within the valve overlap period, the intake manifold air amount is set equal to the overlap stop mode final air amount, serving as an initial value of the intake manifold air amount at the next start of the engine.

Then, the exhaust gas flow rate value M-Q 'of the EGR valve obtained in step 102 is subtracted from the total intake air value inputted to the engine cylinder to obtain an air flow rate value M'.

And calculating the pressure value behind the throttle valve according to the air flow value, the pressure value before the throttle valve, the current environment temperature value, the current environment pressure value and the throttle valve opening.

In the exhaust gas recirculation system, a pressure difference sensor and a valve opening sensor are arranged at a throttle valve, and a temperature sensor and a pressure sensor are arranged at an air inlet pipeline opening of an engine.

Further, the ECU controls a differential pressure sensor provided at the throttle valve to acquire a differential pressure before and after the throttle valve of a current throttle opening, and a specific opening value of the current throttle opening is measured by a valve opening sensor provided at the throttle valve.

The ECU also controls a pressure sensor arranged at the inlet of the engine to acquire a current ambient pressure value which is recorded as P0, and controls a temperature sensor arranged at the inlet of the engine to acquire a current ambient temperature value which is recorded as T0.

And when the ECU receives the air flow value, the pressure value before the throttle valve, the current environment temperature value and the current environment pressure value, calculating to obtain the pressure value behind the throttle valve of the current throttle valve opening.

In the present embodiment, the post-throttle pressure value of the current throttle opening may be calculated according to the following calculation formula;

further, the calculation formula is:

wherein Pout is a pressure value after the throttle valve, pin is a pressure value before the throttle valve, Q is an air flow value, rho is an air density, A is a preset flow area of the throttle valve, and K is a flow calculation correction coefficient, wherein

Optionally, the embodiment is not limited to the calculation method of the pressure value after the other throttle valves.

104. Judging whether the absolute value of the pressure value obtained by subtracting the EGR valve from the pressure value after the throttle valve is smaller than a preset value or not, if not, taking the pressure value after the throttle valve as the new pressure value after the EGR valve, and continuing to execute the step 102; otherwise, the exhaust gas flow value of the EGR valve in step 102 is taken as the current exhaust gas flow value of the EGR valve.

In order to make the result of the calculated current exhaust gas flow value of the EGR valve more accurate, an iterative method is used to calculate, and the preset value is an iteration end condition, which is set as: and (3) taking the initial pressure value after the throttling valve as an initial value of iteration, iterating the calculated pressure value after the throttling valve and the initial value, and when the absolute value of the pressure value after the throttling valve minus the pressure value after the EGR valve in the step (102) is smaller than n, wherein n is a constant approaching 0. In other embodiments, other iteration conditions may be set, and it is within the scope of the present embodiment that the current exhaust gas flow value of the EGR valve is as accurate as possible.

When the iteration condition cannot be met, the accuracy of the obtained result is proved to be not required, and the opening degrees of the EGR valve and the throttle valve are further controlled by the feedback regulation ECU and are recalculated to obtain the current exhaust gas flow value of the EGR valve meeting the iteration condition.

When the iteration end condition is satisfied, the current EGR exhaust gas flow value is output. The feedback control is carried out on the opening degrees of the EGR valve and the throttle valve in an iterative mode, so that the more accurate exhaust gas flow value of the EGR valve is obtained.

As another alternative, in some exhaust gas recirculation systems, a mixing valve is also installed before the EGR valve, whereby a pressure differential can be created upstream and downstream of the EGR valve, thereby allowing the exhaust gas flow value of the EGR valve to be precisely controlled and facilitating more precise measurement by the pressure differential sensor at the EGR valve.

In an alternative embodiment, after performing step 101, the method may further include the following operations: and collecting an initial pressure value behind the throttle valve, and delaying for a preset time length to take the initial pressure value as a pressure value behind the EGR valve.

For example, as shown in fig. 6, fig. 6 is a schematic structural diagram of an engine according to an embodiment of the present invention. The engine includes: a throttle valve 1, an EGR valve 2 and engine cylinders 3.

A valve opening sensor 11 is provided at the throttle valve 1, and a pressure sensor (not shown) is connected to the rear of the throttle valve 1.

A differential pressure sensor 21 and a valve opening sensor 22 are provided at the EGR valve 2, and a temperature sensor 23 is provided between an intake port of the EGR valve 2 and an intercooler 24 of the EGR valve 2.

An intake air flow sensor 31, a temperature sensor (not shown), and a pressure sensor (not shown) are provided at an intake port of the engine cylinder 3.

First, the post-throttle initial pressure value P0-1/2dP is measured using the pressure sensor provided at the throttle valve 1 and substituted as the post-EGR pressure value, i.e., the initial value of the iterative algorithm. In order to make the calculation more accurate, the pressure value after the EGR valve is also delayed, and the next operation is performed after the delay.

Differential pressure sensors

21 and 22 arranged at the EGR valve are used for collecting differential pressure of the EGR valve at the front and the back of the EGR valve under different valve opening degrees, the differential pressure is recorded as dP, and then the pressure value before the EGR valve is determined to be as follows according to the differential pressure dP before and after the EGR valve and the pressure value P0-1/2dP after the EGR valve: p0+ dP, and sending the determined pressure value before the EGR valve to the ECU.

The temperature sensor 23 of the EGR valve 2 after the intercooler 24 and the EGR valve opening sensor 22 are used for collecting the exhaust gas temperature value of an exhaust system pipeline of the EGR valve in front of the EGR valve under different valve openings, the value is recorded as T, and the exhaust gas temperature value of the exhaust system pipeline in front of the EGR valve is sent to the ECU.

The temperature sensor 23 and the differential pressure sensor 21 are directed to the same EGR valve opening degree at the same time.

And calculating the pressure value P0+ dP before the EGR valve and the exhaust gas temperature value T of the exhaust system pipeline before the EGR valve according to the step 102 to obtain the exhaust gas flow value of the EGR valve.

The total intake air amount M input to the engine cylinder 3 is measured by an intake flow sensor 31 provided at an air inlet of the engine cylinder 3, the total intake air amount is subtracted from an exhaust gas flow value of the EGR valve, a current ambient temperature value T0 is measured by a temperature sensor (not shown), and a current ambient pressure value P0 is measured by a pressure sensor (not shown). The post-throttle pressure value is calculated according to step 103.

And (4) iterating the initial pressure value after the throttle valve as an input quantity and the calculated pressure value after the throttle valve until an iteration termination condition is met, namely the difference between the pressure value after the throttle valve and the pressure value after the EGR valve in the step 102 is smaller than n, wherein n is a constant approaching 0, and terminating the calculation process.

Optionally, a mixing valve (not shown) is further installed in front of the EGR valve 2 of the present engine structure, so that a pressure difference can be created between the upstream and downstream of the EGR valve 2, thereby enabling the exhaust gas flow value of the EGR valve 2 to be accurately controlled and facilitating more accurate measurement by a pressure difference sensor at the EGR valve 2.

It can be seen that, in the first embodiment, the acquired parameters of the pressure, the temperature and the like of the throttle valve and the EGR valve can be iteratively calculated by only using a differential pressure sensor, a temperature sensor and the like which are commonly used in the existing engine without additionally adding a sensor, so that the accurate calculation of the exhaust gas flow of the EGR can be realized.

Example two

Referring to fig. 2, fig. 2 is a schematic flow chart illustrating another method for calculating an exhaust gas flow value of an EGR valve according to an embodiment of the present invention. The method described in fig. 2 can be applied to an exhaust gas recirculation system, wherein the exhaust gas recirculation system comprises a throttle valve and an EGR valve, an air outlet pipeline of the throttle valve is communicated with an air outlet pipeline of the EGR valve, and air output by the throttle valve is mixed with exhaust gas output by the EGR valve and then is input into an engine cylinder. The embodiments of the present invention are not limited. As shown in fig. 2, the method for calculating the EGR valve exhaust gas flow rate value may include the operations of:

the preset initial pressure value is used as the pressure value after the EGR valve 201.

The pressure value of the EGR valve is subjected to iteration operation, so that the calculation result is more accurate, an initial pressure value is introduced firstly to start the iteration operation, and for convenience of subsequent calculation, the preset initial pressure value is recorded as P0-1/2dP and is used as the pressure value behind the EGR valve, wherein in the physical sense, P0 can be realized as the current atmospheric pressure value, and dP is the current differential pressure value. It should be noted that the preset initial pressure value is only manually selected to start the whole iteration process, and the specific value is not limited.

202. And calculating the exhaust gas flow value of the EGR valve according to the pressure value after the EGR valve.

First, the differential pressure sensor at the ECU controlled EGR valve collects the differential pressure before and after the EGR valve at different valve opening degrees, and is recorded as dP.

The temperature sensor and the differential pressure sensor are directed to the same EGR valve opening degree at the same time.

In this embodiment, the exhaust gas flow rate value of the EGR valve may be calculated according to the following bernoulli equation, and the specific implementation manner may refer to step 102 described above, which is not described herein again.

Optionally, the embodiment is not limited to other calculation methods for calculating the exhaust gas flow rate value of the EGR valve.

203 calculates the post-throttle pressure value based on the exhaust gas flow rate value of the EGR valve and the total intake air value input to the engine cylinder.

First, the total air intake value input to the engine cylinder is collected and designated as M. The total intake air quantity value input to the cylinder of the engine may be directly collected in the present embodiment based on an intake air flow sensor provided at the intake port of the cylinder.

Thereafter, the exhaust gas flow rate value M-Q 'of the EGR valve obtained in step 102 is subtracted from the total intake air value input to the engine cylinders to obtain an air flow rate value M'.

The ECU also controls a pressure sensor arranged at the air inlet pipeline opening of the engine to acquire a current environmental pressure value which is recorded as P0, and controls a temperature sensor arranged at the air inlet pipeline opening of the engine to acquire a current environmental temperature value which is recorded as T0;

and after the ECU receives the air flow value, the pressure value before the throttle valve, the current environment temperature value and the current environment pressure value, calculating to obtain the pressure value after the throttle valve of the current throttle valve opening.

In this embodiment, the pressure value after the throttle of the current throttle opening may be calculated according to the bernoulli equation, and the specific implementation manner may refer to step 103, which is not described herein again.

204, judging whether the absolute value of the pressure value after the air throttle valve and the EGR valve are subtracted is smaller than the preset value. If not, go to step 205. Otherwise, step 206 is executed to use the exhaust gas flow value of the EGR valve in step 202 as the current exhaust gas flow value of the EGR valve.

In order to make the calculated result of the current exhaust gas flow value of the EGR valve more accurate, an iterative method is used for calculation, and the preset value is an iteration termination condition, which is set as: and taking the initial pressure value after the throttle valve as an initial value of iteration, iterating the calculated pressure value after the throttle valve and the initial value, and when the absolute value of the difference between the pressure value after the throttle valve and the pressure value after the EGR valve in the step 102 is smaller than n, wherein n is a constant approaching 0.

When the iteration end condition is satisfied, the current EGR exhaust gas flow value is output. The opening degrees of the EGR valve and the throttle valve are subjected to feedback control in an iterative calculation mode, so that a more accurate exhaust gas flow value of the EGR valve is obtained.

Therefore, according to embodiment 2, iterative calculation can be performed on the acquired parameters such as the pressure and the temperature of the throttle valve and the EGR valve only by using a differential pressure sensor, a temperature sensor and the like which are commonly used in the existing engine without additionally adding a sensor, so that an accurate pressure value after the throttle valve can be obtained on the basis of accurate calculation of the exhaust gas flow of the EGR, and the accuracy of subsequent related feedback calculation according to the pressure value of the throttle valve can be improved.

EXAMPLE III

Referring to fig. 3, fig. 3 is a schematic flow chart illustrating a method for adjusting engine parameters according to an embodiment of the present invention. Wherein the method described in fig. 3 can be applied to an exhaust gas recirculation system comprising a throttle valve and an EGR valve, an outlet conduit of the throttle valve being in communication with an outlet conduit of the EGR valve, air output from the throttle valve being mixed with exhaust gas output from the EGR valve and being input to an engine cylinder. The embodiments of the present invention are not limited. As shown in FIG. 3, the method of adjusting engine parameters may include the following operations:

301. the current exhaust gas flow value of the EGR valve is obtained using a calculation method of the exhaust gas flow value of the EGR valve as described in fig. 1 or fig. 2.

302. Engine parameters are adjusted based on the current exhaust gas flow of the EGR valve.

Wherein the engine parameters include one or more of EGR rate, engine torque, engine fuel injection, and engine firing angle.

The adjustment method for each engine parameter may be calculated based on demand and an associated formula.

Optionally, the opening degree of a throttle valve can be increased by introducing EGR or excess air into the gasoline engine, the pumping loss is effectively reduced, further, the fuel consumption is reduced, and the fuel consumption can be reduced with higher efficiency by accurately controlling the current exhaust gas flow of the EGR valve.

Alternatively, due to CO in the exhaust gas ₂ And H ₂ O has higher specific heat ratio, EGR can absorb a large amount of heat in the compression and combustion processes, the temperature in the cylinder is reduced, the spontaneous combustion tendency of the tail end mixed gas is reduced, and the more efficient spontaneous combustion inhibition can be realized through the accurate current exhaust gas flow of the EGR valve.

Optionally, because the EGR dilutes the combustible mixture, the collision probability of fuel molecules and oxygen molecules is reduced, and the reaction rate of the tail end mixture before flame is reduced. Higher reaction rates before a reduced end-mixed gas flame can be achieved by accurate EGR valve current exhaust gas flow.

Therefore, according to the third embodiment, efficient control of engine parameters, such as the EGR rate, the engine torque, the fuel injection amount, the ignition angle and the like, through accurate exhaust gas flow of the EGR valve can be realized, so that the fuel economy of the engine is improved, the exhaust gas emission can be reduced, and the occurrence of knocking can be inhibited.

Example four

Referring to fig. 4, fig. 4 is a schematic diagram of a system for calculating an exhaust gas flow rate of an EGR valve according to an embodiment of the present invention. The system described in fig. 4 can be applied to an exhaust gas recirculation system, which includes a throttle valve and an EGR valve, wherein an air outlet pipeline of the throttle valve is communicated with an air outlet pipeline of the EGR valve, and air output by the throttle valve is mixed with exhaust gas output by the EGR valve and then input into an engine cylinder. The embodiments of the present invention are not limited. As shown in fig. 4, the system may include:

and the acquisition module 401 is configured to use a preset initial pressure value as a pressure value after the EGR valve.

The first calculating module 402 is configured to calculate an exhaust gas flow rate value of the EGR valve according to the pressure value after the EGR valve.

A second calculation module 403 is used for calculating the pressure value after the throttle valve according to the exhaust gas flow value of the EGR valve and the total air intake value input into the engine cylinder.

An iteration module 404, configured to determine whether an absolute value of the pressure value obtained by subtracting the EGR valve in the first calculation module 402 from the pressure value after the throttle valve is smaller than a preset value, if not, take the pressure value after the throttle valve as a new pressure value after the EGR valve, and continue to execute the first calculation module 402; otherwise, the exhaust gas flow value of the EGR valve in the first calculation module 402 is taken as the current exhaust gas flow value of the EGR valve.

It can be seen that, the implementation of the device described in fig. 4 can perform iterative calculation on the collected parameters such as the pressure and the temperature of the throttle valve and the EGR valve by using only a differential pressure sensor, a temperature sensor and the like which are commonly used in the existing engine without adding an additional sensor, so that accurate calculation of the exhaust gas flow rate of the EGR can be realized.

In an alternative embodiment, the first computing module 402 includes a first acquisition unit 4021, a second acquisition unit 4022, and a computing unit 4023. A differential pressure sensor and a valve opening sensor are arranged at the EGR valve, and a temperature sensor is arranged between an air inlet of the EGR valve and an intercooler of the EGR valve.

The pressure sensor at the position of the EGR valve is controlled by the first acquisition unit 4021 to acquire the pressure difference of the EGR valve before and after the EGR valve under different valve opening degrees, the pressure difference is recorded as dP, the pressure sensor at the position of the EGR valve is controlled to acquire the pressure value before the EGR valve, the pressure value is recorded as P0+ dP, and the determined pressure value before the EGR valve is sent to the ECU.

And then the second acquisition unit 4022 controls a temperature sensor based on the EGR intercooler to acquire the exhaust gas temperature value of the exhaust system pipeline of the EGR valve in front of the EGR valve under different valve opening degrees, the value is recorded as T, and the exhaust gas temperature value of the exhaust system pipeline in front of the EGR valve is sent to the ECU.

The calculating unit 4023 is configured to calculate an exhaust gas flow rate value of the EGR valve after the ECU receives the determined pressure value P0+ dP before the EGR valve and the exhaust gas temperature value T of the exhaust system pipeline before the EGR valve.

further, the bernoulli equation is:

As an alternative embodiment, the calculation process performed in the second calculation module 402 is as follows:

The total intake air value input to the engine cylinders is then subtracted by the EGR valve exhaust flow value M-Q 'obtained by the first calculation module 402 to obtain the airflow value M'.

As an alternative embodiment, in order to make the result of the calculated current exhaust gas flow value of the EGR valve more accurate, the iteration module 404 is used to calculate by an iterative method, where the preset value of the iteration module 404 is an iteration end condition, and in this embodiment, the iteration end condition is set as: and taking the initial pressure value after the throttling valve as an initial value of iteration, iterating the calculated pressure value after the throttling valve and the initial value, and when the difference between the pressure value after the throttling valve and the pressure value after the EGR valve in the first calculation module 402 is less than n, wherein n is a constant approaching 0. In other embodiments, other iteration conditions may be set, and it is within the scope of the present embodiment that the current exhaust gas flow value of the EGR valve is as accurate as possible.

When the iteration condition cannot be met, the accuracy of the obtained result is proved to be not up to the requirement, and the opening degrees of the EGR valve and the throttle valve are further controlled by the feedback regulation ECU and are recalculated to obtain the current exhaust gas flow value of the EGR valve meeting the iteration condition.

When the iteration end condition is satisfied, the current EGR exhaust gas flow value is output. The opening degrees of the EGR valve and the throttle valve are subjected to feedback control in an iterative mode, so that a more accurate exhaust gas flow value of the EGR valve is obtained.

As an alternative embodiment, a mixing valve (not shown) is further installed in front of the EGR valve of the engine structure, so that a pressure difference can be created between the upstream and downstream of the EGR valve involved in the calculation means of the exhaust gas flow value of the EGR valve, thereby allowing the exhaust gas flow value of the EGR valve to be accurately controlled and facilitating more accurate measurement by the pressure difference sensor at the EGR valve.

EXAMPLE five

Referring to fig. 5, fig. 5 is a schematic structural diagram of an engine parameter adjusting device according to an embodiment of the present invention. The device described in fig. 5 can be applied to an exhaust gas recirculation system, which includes a throttle valve and an EGR valve, wherein an air outlet pipeline of the throttle valve is communicated with an air outlet pipeline of the EGR valve, and air output by the throttle valve is mixed with exhaust gas output by the EGR valve and then input into an engine cylinder. The embodiments of the present invention are not limited. As shown in fig. 5, the apparatus may include:

a memory 501 in which executable program code is stored;

a processor 502 coupled to a memory 501;

the processor 502 calls the executable program code stored in the memory 501 for executing the method of adjusting the engine parameter described in the third embodiment.

EXAMPLE six

An embodiment of the present invention discloses a computer-readable storage medium storing a computer program for electronic data exchange, wherein the computer program causes a computer to execute the method of calculating an EGR valve exhaust gas flow rate value described in the first embodiment or the second embodiment.

EXAMPLE seven

An embodiment of the present invention discloses a computer program product, which includes a non-transitory computer-readable storage medium storing a computer program, and the computer program is operable to cause a computer to execute the method of calculating an EGR valve exhaust gas flow rate value described in the first or second embodiment.

The above-described embodiments are only illustrative, and the modules described as separate parts may or may not be physically separate, and the parts displayed as modules may or may not be physical modules, may be located in one place, or may be distributed on a plurality of network modules. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.

Through the above detailed description of the embodiments, those skilled in the art will clearly understand that each embodiment may be implemented by software plus a necessary general hardware platform, and may also be implemented by hardware. With this understanding in mind, the above technical solutions may essentially or in part contribute to the prior art, be embodied in the form of a software product, which may be stored in a computer-readable storage medium, including a Read-Only Memory (ROM), a Random Access Memory (RAM), a Programmable Read-Only Memory (PROM), an Erasable Programmable Read-Only Memory (EPROM), a One-time Programmable Read-Only Memory (OTPROM), an electronically Erasable Programmable Read-Only Memory (EEPROM), an optical Disc-Read (CD-ROM) or other storage medium capable of storing data, a magnetic tape, or any other computer-readable medium capable of storing data.

Finally, it should be noted that: the method and the device for calculating the exhaust gas flow rate of the EGR valve disclosed in the embodiments of the present invention are only preferred embodiments of the present invention, and are only used for illustrating the technical solution of the present invention, rather than limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those skilled in the art; the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for calculating an exhaust gas flow value of an EGR valve is applied to an exhaust gas recirculation system, the exhaust gas recirculation system comprises a throttle valve and the EGR valve, an air outlet pipeline of the throttle valve is communicated with an air outlet pipeline of the EGR valve, air output by the throttle valve is mixed with exhaust gas output by the EGR valve and then input into an engine cylinder, and the method comprises the following steps:

c, calculating a pressure value after the throttle valve according to the exhaust gas flow value of the EGR valve and the total air intake value input into an engine cylinder;

d, judging whether the absolute value of the pressure value after the throttling valve minus the pressure value after the EGR valve is smaller than a preset value or not, if not, taking the pressure value after the throttling valve as a new pressure value after the EGR valve, and continuing to execute the step b; otherwise, taking the exhaust gas flow value of the EGR valve in the step b as the current exhaust gas flow value of the EGR valve;

wherein, the calculating the exhaust gas flow value of the EGR valve according to the pressure value after the EGR valve comprises the following steps:

collecting the pressure difference before and after the EGR valve by using a pressure difference sensor;

determining and collecting a pressure value before the EGR valve according to the pressure difference before and after the EGR valve and the pressure value after the EGR valve;

q' is an exhaust gas flow value of the EGR valve, A is a preset flow area of the EGR valve, Δ p is a pressure difference between the front and the rear of the EGR valve, ρ is an exhaust gas density, and K is a flow calculation correction coefficient.

2. The method of calculating an EGR valve exhaust gas flow value according to claim 1, characterized in that the exhaust gas density is calculated according to the following formula:

3. The method for calculating an EGR valve exhaust gas flow value according to claim 1, wherein said calculating the post-throttle pressure value based on the EGR valve exhaust gas flow value and the total intake air quantity value inputted to the engine cylinder comprises:

collecting a total air intake value input into an engine cylinder;

subtracting the waste gas flow value of the EGR valve from the total air inflow value to obtain an air flow value;

4. The method for calculating the exhaust gas flow value of the EGR valve according to claim 3, wherein the calculating the pressure value after the throttle valve based on the air flow value, the pressure value before the throttle valve, the current ambient temperature value, the current ambient pressure value, and the throttle opening degree comprises:

collecting a current ambient pressure value by using a pressure sensor;

wherein Pout is a pressure value after the throttle valve, pin is a pressure value before the throttle valve, Q is an air flow value, ρ is an air density, a is a preset flow area of the throttle valve, and K is a flow calculation correction coefficient, wherein the air density is calculated according to the following formula:

5. The method for calculating the EGR valve exhaust gas flow rate value according to claim 1, wherein said determining whether an absolute value of the value obtained by subtracting the EGR valve post-pressure value from the pressure value after the throttle valve is smaller than a preset value further comprises:

and if not, taking the exhaust gas flow value of the EGR valve calculated according to the pressure value after the EGR valve as the current pressure value after the throttle valve.

6. A method of adjusting an engine parameter, the method comprising:

obtaining a current exhaust gas flow value of the EGR valve using the calculation method of an exhaust gas flow value of the EGR valve according to any one of claims 1 to 5;

7. A system for calculating an exhaust gas flow rate of an EGR valve, the system being applied to an exhaust gas recirculation system, the exhaust gas recirculation system including a throttle valve and an EGR valve, an outlet pipe of the throttle valve being in communication with an outlet pipe of the EGR valve, air output from the throttle valve being mixed with exhaust gas output from the EGR valve and then being input to a cylinder of an engine, the system comprising:

the second calculation module is used for calculating a pressure value after the throttle valve according to the exhaust gas flow value of the EGR valve and the total air intake value input into the cylinder of the engine;

the iteration module is used for judging whether the absolute value of the pressure value obtained by subtracting the EGR valve in the first calculation module from the pressure value after the throttling valve is smaller than a preset value or not, if not, taking the pressure value after the throttling valve as a new pressure value after the EGR valve, and continuously executing the first calculation module; if not, taking the exhaust gas flow value of the EGR valve in the first calculation module as the current exhaust gas flow value of the EGR valve;

wherein the first computing module comprises:

the first acquisition unit is used for acquiring the pressure difference before and after the EGR valve through a pressure difference sensor and determining the pressure value before the EGR valve according to the pressure difference before and after the EGR valve and the pressure value after the EGR valve;

a calculation unit for calculating an exhaust gas flow rate value of the EGR valve according to the following formula;

q' is an exhaust gas flow value of the EGR valve, A is a preset flow area of the EGR valve, delta P is a pressure difference between the front and the rear of the EGR valve, K is a flow calculation correction coefficient, and rho is an exhaust gas density.

8. The system for calculating an EGR valve exhaust gas flow value according to claim 7, characterized in that the exhaust gas density is calculated according to the following equation:

9. The system for calculating the EGR valve exhaust gas flow rate value according to claim 8, wherein the iteration module is further configured to use the exhaust gas flow rate value of the EGR valve calculated according to the pressure value after the EGR valve as the current pressure value after the throttle valve when judging whether the absolute value of the pressure value after the throttle valve minus the pressure value after the EGR valve in the first calculation module is smaller than a preset value.

10. An engine parameter adjustment device, characterized in that the device comprises:

a memory storing executable program code;

a processor coupled with the memory;

the processor invokes the executable program code stored in the memory to perform the method of adjusting an engine parameter of claim 6.