KR101060967B1 - EBR flow control device and its control method using THHRRMA flow rate measurement - Google Patents

Abstract

The present invention relates to an apparatus for controlling an EGR flow rate using a THERMAL flow rate measurement and a control method thereof, and more specifically, to a recirculation tube in which an EGR valve is installed, to measure a first temperature along a flow direction of an EGR gas flowing in one direction. The sensor, the heater, and the second temperature measuring sensor are sequentially installed, and when the heat radiation of the heater occurs, the first temperature measuring sensor obtains power consumption by measuring the temperature when there is no flow of EGR gas, and measures the second temperature. The sensor measures the power consumption by measuring the temperature of the EGR gas flowing through the heater when the flow rate of the EGR gas is present, so that the flow rate of the EGR gas corresponding to the power consumed when mounted in the engine can be obtained. EGR flow control device using the THERMAL flow rate measurement that enables the optimization of the EGR system through precise control of the EGR valve control It relates to a method.

EGR, flow control, flow measurement, heater, heat transfer rate, flow rate, valve

Description

Flow rate control device and its control method using THRRMAAL flow velocity measurement {FLOW RATE CONTROL APPARATUS USING THERMAL FLOW VELOCITY MEASUREMENT AND METHOD THEREOF}

The present invention relates to an EGR flow rate control apparatus using a THERMAL flow rate measurement applicable to an engine and a vehicle of a vehicle equipped with an EGR system, and a control method thereof.

In accordance with the recent tightening environmental regulations, the reduction of pollutants emitted from automobiles is the largest major R & D goal of the automobile industry around the world. HC, CO, and soot among automobile exhaust gases are relatively easy to reduce by the improvement of combustion and post-treatment. However, the reduction of nitrogen oxide technology has been difficult to develop due to the adverse effect on combustion and fuel efficiency.

Exhaust gas recirculation (EGR), which is an exhaust gas recirculation apparatus used as one of such nitrogen oxide reduction techniques, has already been put to practical use as one of the inexpensive and effective methods for reducing nitrogen oxides. This is because CO2 or H2O of the exhaust gas is replaced with a part of the intake air, thereby increasing the heat capacity of the mixer to suppress the rise of the combustion gas temperature in the cylinder, and reducing the overall excess of NOx by lowering the excess air rate to suppress thermal NOx generation. In addition, since part of the intake air is replaced by exhaust gas having a low oxygen concentration, the generation of NOx is suppressed because the oxygen in the combustion chamber is reduced.

However, as the exhaust gas regulations become more stringent, it is difficult to precisely and quickly control the required EGR rate by conventional methods, which limits the reduction of NOx.In order to compensate for this, the vehicle is discharged by organically connecting ECUs and various sensors and actuators. Techniques for controlling EGR rates, which have a significant impact on gas emissions and engine combustion stability, have been developed and applied.

In order for the EGR system to be commercialized under such various operating conditions, it is necessary to change the core parts (EGR valve, EGR heat exchanger), etc., which are part of the EGR system, and to understand the effects of operating performance and flow characteristics according to the internal structure. Problems due to the high temperature characteristics of EGR systems installed on gasoline and diesel engines, as well as EGR gas containing a large amount of particulate matter (PM), pass through the intake flow system, causing contamination of various parts and making mechanical measurements. When using the equipment, there is a problem that it is difficult to control the exact EGR rate.

The present invention has been made to solve the above problems, the object of the present invention is to apply the EGR system to the actual engine, the EGR system through the flow rate measurement of the EGR gas for precise control of the EGR system for each major factor An object of the present invention is to provide an EGR flow control device using a THERMAL flow rate measurement and a control method thereof.

Other objects and advantages of the invention will be described below and will be appreciated by the embodiments of the invention. Furthermore, the objects and advantages of the present invention can be realized by means and combinations indicated in the claims.

The present invention is a means for solving the above problems, one end is installed in each of the recirculation pipe is installed EGR valve is installed, the inside of the recirculation pipe flows in one direction, the EGR gas is changed according to the operating conditions of the engine A first temperature sensor for measuring the temperature of the sensor; A heater that generates heat in the recirculation tube; The second temperature measuring sensor for measuring the temperature of the EGR gas after passing through the heater, consisting of, the heat transfer amount increases and decreases when the flow rate of the EGR gas through the heater electrically heated in the flow of the EGR gas flow rate Thus, by measuring the flow rate of the EGR gas corresponding to the power consumed when mounted to the engine, it is possible to control the EGR valve, it is possible to optimize the EGR system.

As described above, when the EGR system is applied to an actual engine, the EGR system can be optimized by measuring the flow rate of the EGR gas for precise control of the EGR system for each major factor.

Before describing the various embodiments of the present invention in detail, it will be appreciated that the application is not limited to the details of construction and arrangement of components described in the following detailed description or illustrated in the drawings. The invention may be embodied and carried out in other embodiments and carried out in various ways. It should also be noted that the device or element orientation (e.g., "front," "back," "up," "down," "top," "bottom, Expressions and predicates used herein for terms such as "left," " right, "" lateral, " and the like are used merely to simplify the description of the present invention, Or that the element has to have a particular orientation. In addition, terms such as “first” are used in this disclosure and the appended claims for purposes of illustration and are not intended to indicate or mean the relative importance or spirit.

The present invention has the following features to achieve the above object.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms or words used in this specification and claims should not be construed as being limited to the ordinary or dictionary meanings, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention.

Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

Hereinafter, an EGR flow control apparatus using a THERMAL flow rate measurement and a control method thereof will be described in detail with reference to FIGS. 1 to 3.

1 is a schematic diagram of an engine to which the EGR system is applied, and generally, the EGR passage of the gasoline engine is connected to the exhaust pipe 50 after the throttle valve of the intake pipe 40. Since the pressure on the intake side is negative and lower than the exhaust pipe 50 pressure, it is easy to recycle the exhaust gas, and the amount of EGR depends on the opening and closing area of the EGR valve 80 and the pressure difference between the intake and exhaust pipes 40 and 50 provided in the middle of the passage. Adjust.

However, in the diesel engine, since the throttle valve is not provided in the intake pipe 40, the pressure difference between the intake pipes 40 and 50 is not large, which makes it difficult to control the flow rate. Therefore, in such an engine, it is difficult to control the EGR valve 80 which acts as an important variable for the formation and supply of the EGR flow rate unless the accurate EGR gas flow rate is measured.

According to the measurement principle, there are differential pressure method using volumetric flow rate and pressure drop, insertion volume method based on various principles, ultrasonic detection method, and electronic method.

In the case of EGR flow measurement, it is better not to install an obstruction facility in the flow path in order to increase the limit of EGR supply and EGR rate smoothly, and since the PM contains a large amount of EGR gas, it may cause contamination on the surface during circulation. Or orifice type flow measurement methods are not suitable.

In the present invention, when there is an electrically heated wire in the flow of the fluid of the hot air flow meter, the flow rate of the EGR gas is measured by using the principle of increasing or decreasing the heat transfer amount according to the flow rate.

At this time, the EGR gas flow rate measurement site is preferably mounted after the EGR cooler 90 having a low gas temperature in the EGR supply flow path.

Figure 2 is a schematic diagram of the EGR gas flow rate measuring apparatus according to the present invention, it is also an enlarged view of the portion 'A' of Figure 1 as shown in the figure. Three probes are embedded through the pipe wall, each of which is sealed at each 'B' portion of FIG. 2 to prevent the EGR gas from leaking out.

In the case of the flow rate measuring device configured as described above, it is possible to prevent breakage that is a problem in a general hot air flowmeter, and to solve the problem of contamination and repeatability by PM (Particulate Matter).

The plurality of probes are the first temperature measuring sensor 10, the heater 20, and the second temperature measuring sensor 30, respectively, and the first temperature measuring sensor 10 and the heater 20 are directed toward the flow direction of the flow rate. In this case, the second temperature measuring sensor 30 is installed in order, and the first temperature measuring sensor 10 measures a temperature of another EGR gas according to an operating condition of the engine 60. In this case, in order to minimize the loss due to heat transfer to the outside, the distance between the first and second temperature measuring sensors 10 and 30 may be close to each other.

When heat is generated in the heater 20, a temperature difference is generated between the temperature measured by the second temperature measuring sensor 30 and the temperature according to the invention in the actual heater 20, where the temperature difference is flowed. It depends on the flow rate of the EGR gas.

The heat transfer amount increases and decreases according to the flow rate, and thus the temperature changes. As the speed increases and the heat transfer amount increases, more energy is required to maintain a constant temperature difference. Considering the thermal equilibrium, it is assumed that heat transfer from the heater 20 is mainly by convection, and heat transfer by conduction and radiation can be ignored, and considering the heat transfer from the cylinder placed in the flow field, the power of the heater 20 is considered. The relation as shown in the following first equation is established between P and the flow rate U.

[First Math Formula]

Here, P is the power consumed by the heater 20 at a constant temperature, P ₀ is the power consumed when there is no flow in the flow field, U is the flow rate of the EGR gas, C and n is a constant determined by the experimental conditions . At this time, the temperature is a temperature measured by the second temperature sensor 30, the above equation is sensitive to various environments (fluid temperature, temperature of the heater 20, etc.), the linearity that a general sensor should have Since C and n values for each variable, such as the temperature of EGR gas, the flow rate, and the power of the heater 20, must be determined in advance by experiment.

When the values of C and n are determined, the EGR gas flow rate can be obtained from the EGR gas temperature measured by the first temperature measuring sensor 10 and the temperature of the fluid in the heater 20 and the second temperature measuring sensor 30. This value is sent to an ECU (Engine Control Unit) (not shown) to serve as a reference for controlling the EGR gas flow rate.

In more detail,

If heat radiation is generated by the heater 20 while the first and second temperature sensors 10 and 30 and the heater 20 are mounted, P ₀ when there is no flow rate, that is, power consumption when there is no flow rate Is available,

When the flow rate is present, P (power consumption of the heater 20) increases with an increase in flow rate in order to maintain a constant value measured by the second temperature measuring sensor 30.

If the power consumption and the flow rate are known by experiment, C and n can be obtained from the above first equation. Then, for example, it is possible to obtain a graph relating to power and flow velocity as shown in FIG. 3, wherein the first temperature measuring sensor 10, the second temperature measuring sensor 30, and the heater 20 are connected to the recirculation pipe 70. When mounted, the flow rate corresponding to the power consumed by the heater 20 can be obtained.

As mentioned above, although this invention was demonstrated by the limited embodiment and drawing, this invention is not limited by this, The person of ordinary skill in the art to which this invention belongs, Various modifications and changes may be made without departing from the scope of the appended claims.

1 is a schematic diagram of an engine to which an EGR system is applied.

2 is a schematic diagram of an EGR flow control apparatus according to the present invention;

Figure 3 is a graph of the power and flow rate according to an embodiment applying the EGR flow control device and the control method according to the present invention.

<Indication of symbols for main parts of drawing>

10: first temperature measuring sensor 20: heater

30: second temperature measuring sensor 40: intake pipe

50: exhaust pipe 60: engine

70: recirculation pipe 80: EGR valve

90: EGR cooler

Claims (9)

One end is installed in each of the recirculation pipe 70 is installed EGR valve 80, A first temperature measuring sensor (10) flowing inside the recirculation pipe (70) in one direction and measuring a temperature of an EGR gas which varies according to an operating condition of the engine (60); A heater 20 that generates heat in the recirculation tube 70; And a second temperature measuring sensor 30 for measuring the EGR gas temperature after passing the heater 20, The first temperature measuring sensor 10 and the second temperature measuring sensor (by using the principle of increasing or decreasing the heat transfer amount when there is a flow rate of the EGR gas through the heater 20 electrically heated in the flow of the EGR gas flow rate) 30) and THERMAL flow rate measurement to enable the control of the EGR valve 80 by measuring the flow rate of the EGR gas corresponding to the power consumed by the heater 20 when the heater 20 is mounted to the recirculation pipe 70 In the EGR flow control method using EGR gas flow rate measurement is enabled by the following first equation, [First Math Formula]

Where P is the power consumed by the heater 20 at a constant temperature, P ₀ is the power consumed when there is no flow in the flow field, U is the flow rate of the EGR gas, and C and n are constants determined by experimental conditions. Indicates.) The first temperature sensor 10, the heater 20, and the second temperature sensor 30 are mounted after the EGR cooler 90 having a low gas temperature in the EGR supply flow path. The P is obtained when it is simultaneously increased with the flow rate in order to maintain the temperature measured from the second temperature measuring sensor 30 at a constant value in the presence of the flow rate of the EGR gas, The P ₀ is obtained when there is no flow rate of EGR gas and heat radiation is generated by the heater 20 in a state in which the first and second temperature measuring sensors 10 and 30 and the heater 20 are mounted. EGR flow control method using THERMAL flow rate measurement. delete The method of claim 1, The first temperature measuring sensor 10, the heater 20, and the second temperature measuring sensor 30 are sequentially installed in the recirculation pipe 70 in a direction in which the EGR gas flows. EGR flow control method using measurement. The method of claim 1, The first temperature measuring sensor (10) and the second temperature measuring sensor (30) is an EGR flow rate control method using the THERMAL flow rate measurement, characterized in that installed adjacent to each other to minimize the loss due to heat transfer to the outside. The method of claim 1, The first temperature sensor 10, the heater 20, and the second temperature sensor 30 prevent breakage that is a problem in a general hot air flow meter, and prevent the PM (Particulate Matter) of the flowing gas. EGR flow rate control method using the THERMAL flow rate measurement, characterized in that the EGR gas is not leaked to the outside by performing a sealing process during each installation in the recirculation pipe (70) to solve the contamination caused by. delete delete delete The method according to any one of claims 1 and 3 to 5, Wherein C and n can be derived by obtaining P ₀ and P EGR flow rate control method using the THERMAL flow rate measurement.

Images