KR20180035532A - An intake air control device for engine having dual loop EGR system and electric supercharger - Google Patents

Abstract

The present invention relates to an intake air control device for an engine having an electronic two-stage supercharger system and a dual loop exhaust gas recirculation (EGR) system, capable of easily realizing a supercharging pressure of a set value. According to the present invention, the device comprises: a turbocharger wherein a turbine is disposed on an exhaust flow path extended from an exhaust manifold of an engine and a compressor is disposed on an intake flow path extended from an intake manifold; an electronic supercharger disposed on a downstream side of the compressor of the turbocharger; a low pressure (LP)-EGR device including an LP-EGR flow path to connect a rear end of the turbine to a front end of the compressor, and a LP-EGR valve disposed on the LP-EGR flow path; a high pressure (HP)-EGR device including an HP-EGR flow path to connect the front end of the turbine to the rear end of the supercharger and an HP-EGR valve disposed on the HP-EGR flow path; an LP-EGR flow rate measurement device installed on the front end of the compressor to measure the LP-EGR flow rate supplied to intake air; an HP-EGR flow rate measurement device installed on the rear end of the supercharger to measure the HP-EGR flow rate supplied to intake air; a supercharging pressure measurement means to measure the supercharging pressure of air passing through the intake manifold supplied to the engine; and an intake air control unit including map data to control the revolutions per minute (RPM) of the engine, supercharging pressure for fuel consumption, and target value of the total EGR flow rate, and controlling operation of the supercharger, and the LP/HP-EGR valves to satisfy the target value of the map data.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an intake control device for an internal combustion engine having an electronic two-stage supercharging system and a dual-loop EGR system,

The present invention relates to an intake control system in an engine having a two-stage supercharging system and a dual-loop EGR system, wherein the two-stage supercharging system is composed of an electronic supercharger and a general turbocharger, The present invention relates to an intake control device capable of easily adjusting a boost pressure to a target value while freely adjusting a distribution ratio between an LP-EGR flow rate and an HP-EGR flow rate.

Recently, the problem of air pollution due to the use of fossil fuels and exhaust gas emissions has been continuously raised. In this situation, the exhaust gas recirculation (EGR) system applied to the engine is regarded as an effective way to reduce the exhaust gas.

In the exhaust gas recirculation system for reducing NOx, that is, the EGR system, a part of exhaust gas discharged after combustion is introduced into the combustion chamber to adjust the density of the mixture without changing the air-fuel ratio of the mixture itself The combustion temperature is lowered.

That is, when it is necessary to reduce the exhaust gas such as NOx according to the operation state of the engine, a part of the exhaust gas is supplied to the intake side through the EGR valve and flows into the combustion chamber together with the mixer, Since the mixing ratio of the air and the fuel of the gas mixture does not change, the density of the gas mixture is relatively lowered to lower the propagation speed of the flame, thereby preventing the increase of the combustion temperature, thereby reducing the generation of NOx.

When the EGR system is applied to an engine equipped with a turbocharger, there are two main approaches. One such method is a low-pressure EGR (LP-EGR) system that recirculates the exhaust gas past the turbocharger's turbine to the intake passageway upstream of the compressor, and the other is the exhaust gas flow between the exhaust manifold and the turbine High pressure EGR (HP-EGR) system in which the compressor is recirculated to the intake passage past.

From the viewpoint of the response of the EGR system, the response of the HP-EGR system is fast and the response of the LP-EGR system is slow. In the case of the LP-EGR system, since the pressure at the rear end of the turbine is used as the driving force for recirculating the exhaust gas, the responsiveness is poor. Also, since the back pressure fluctuation occurs at the rear end of the turbine due to the influence of the supercharging degree, Which is difficult to control freely.

However, the LP-EGR system does not affect the turbocharger because it extracts the exhaust gas after the turbine, and it can improve the responsiveness of the turbocharger, that is, the driving ability, because exhaust gas energy can be used.

In addition, the LP-EGR system recirculates the exhaust gas at the rear end of the turbocharger, thereby improving the fuel efficiency by increasing the supercharging efficiency. When the exhaust gas at the rear end of the exhaust gas post-treatment apparatus is recirculated, EGR gas can be supplied, which is advantageous in reducing NOx.

As described above, the LP-EGR system and the HP-EGR system tend to have opposite advantages and disadvantages. Therefore, a dual-loop EGR system using the LP-EGR system and the HP-EGR system is introduced little by little in order to make the advantages of the LP-EGR system and the HP-EGR system compatible.

However, it has not yet been fully compatible with the advantages of the LP-EGR system and the HP-EGR system. Therefore, it is necessary to improve the exhaust gas regulations. In particular, It is necessary to develop a new intake system to satisfy all the difficult requirements.

Korean Registered Patent No. 10-1553301 (Announced 2015.09.16)

The present invention provides both a LP-EGR system and an HP-EGR system in a two-stage supercharging system including an electronic supercharger and a general turbocharger, and is capable of freely adjusting the distribution ratio of the LP-EGR flow rate and the HP- And it is an object of the present invention to provide an intake control device that can be easily achieved with a set value.

The intake control device according to the present invention is applied to an engine equipped with an electronic two-stage supercharging system and a dual-loop EGR system, in which a turbine is disposed on an exhaust flow passage extending from an exhaust manifold of the engine, An LP-EGR passage for connecting a rear end of the turbine to a front end of the compressor, and an LP-EGR passage for connecting the front end of the compressor to the LP- An HP-EGR passage for connecting the front end of the turbine and the rear end of the supercharger, and an HP-EGR passage disposed on the HP-EGR passage, An LP-EGR flow rate measuring device installed at a front end of the compressor and measuring an LP-EGR flow rate supplied to an intake air; an HP-EGR valve installed at a rear end of the supercharger, To Tert-HP EGR flow rate measuring device for measuring the HP-EGR flow rate; and, means for measuring boost pressure of the intake manifold through the measured boost pressure of the air introduced into the engine; And map data for setting a target value of RPM and fuel consumption of the engine and a target value of a total EGR flow rate, wherein the operation of the supercharger and the LP-EGR valve and the HP-EGR valve And an intake control unit for feedback-controlling the operation of the intake control unit.

The target value data of the total EGR flow rate included in the map data includes a distribution ratio of the LP-EGR flow rate and the HP-EGR flow rate, and the intake control unit calculates a distribution ratio of the LP-EGR flow rate and the HP- The operation of the LP-EGR valve and the operation of the HP-EGR valve can be respectively feedback-controlled.

According to an embodiment of the present invention, the LP-EGR flow rate measuring device and the HP-EGR flow rate measuring device may be a carbon dioxide sensor.

The intake control system of the present invention having the above-described configuration comprises a two-stage supercharging system including an electronic supercharger and a general turbocharger, and a final supercritical pressure can be controlled by an electronic supercharger. It is possible to easily adjust the boost pressure to the target value while freely adjusting the flow rate distribution ratio.

In addition, according to the control strategy of the EGR valve and the electronic supercharger, it is possible to easily establish various engine operation strategies such as focusing on fuel efficiency improvement or exhaust gas reduction, thereby greatly reducing the development schedule of engines and vehicles.

Further, since the system is applied to an intake line of an engine, it can be widely applied to engines having various combustion characteristics such as spark ignition engines, compression ignition engines, and new combustion internal combustion engines.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of an intake control device in an engine having an electronic two-stage supercharging system and a dual-loop EGR system according to the present invention; FIG.
2 is a view schematically showing control logic of an intake control unit;

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In describing the embodiments of the present invention, a description of well-known structures that can be easily understood by those skilled in the art will be omitted so as not to obscure the gist of the present invention. In the drawings, like reference numerals refer to like elements throughout. The same elements will be denoted by the same reference numerals even though they are shown in different drawings. Referring to the drawings, The size of the elements, etc., may be exaggerated for clarity and convenience of explanation.

In describing the components of the embodiment of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are intended to distinguish the constituent elements from other constituent elements, and the terms do not limit the nature, order or order of the constituent elements. When a component is described as being "connected", "coupled", or "connected" to another component, the component may be directly connected or connected to the other component, Quot; coupled "or" connected "indirectly while intervening in the context of the present invention.

FIG. 1 is a view schematically showing an intake control device in an engine having an electronic two-stage supercharging system and a dual-loop EGR system according to the present invention.

The present invention will be described in detail with reference to FIG. 1 attached hereto.

The intake control device of the present invention is a two-stage supercharging system, which is an engine 1 equipped with an electronic supercharger 20 and a general turbocharger 10. [

Here, the electronic supercharger 20 means a supercharging effect such as a turbocharger 10 using a compressor that operates with an electric motor. Therefore, there is no turbine 12 rotated by the pressure of the exhaust gas as in the general turbocharger 10, and it is not necessary to supply the rotational power of the engine 1 by using the power transmission mechanism like the mechanical supercharger. Therefore, it is possible to install the engine without greatly changing the existing engine design, and there is a high degree of freedom of being able to operate only as much as desired without being influenced by the operation of the engine 1, such as a general turbocharger 10 or a mechanical supercharger. However, since it is an apparatus using an electric motor, it is appropriate to use it as an auxiliary supercharging means.

The turbine 12 of the turbocharger 10 is arranged such that the turbine 12 is disposed on the exhaust flow path extending from the exhaust manifold of the engine 1 and the compressor 14 is disposed on the intake flow path extending from the intake manifold do.

The electronic supercharger 20 is disposed on the downstream side of the compressor 14 of the turbocharger 10 so that the primary supercharged air from the compressor 14 of the turbocharger 10 As well.

Meanwhile, the intake air control apparatus according to the present invention includes a dual-loop EGR system including an LP-EGR apparatus 30 and an HP-EGR apparatus 40 together with an electronic two-stage supercharging system.

The LP-EGR device 30 includes an LP-EGR passage 32 for connecting the rear end of the turbine 12 of the turbocharger 10 and the front end of the compressor 14, And an LP-EGR valve 34. The flow rate of the LP-EGR supplied to the intake air is regulated by the opening amount of the LP-EGR valve 34. [

The HP-EGR device 40 includes an HP-EGR passage 42 connecting the front end of the turbine 12 of the turbocharger 10 and the rear end of the electronic supercharger 20, And an HP-EGR valve 44 disposed on the engine. That is, the HP-EGR is supplied to the intake air after both of the intake and exhaust stages are completed. As in the case of the LP-EGR apparatus 30, the flow rate of the HP-EGR supplied to the intake air is regulated by the opening amount of the HP-EGR valve 44.

In order to control the total EGR flow rate supplied to the intake air through the dual-loop EGR system, it is necessary to measure the EGR flow rate or the ratio at a point before passing through the rear end of the electronic supercharger 20 and into the intake manifold. In order to control the ratio of the LP-EGR flow rate to the HP-EGR flow rate, that is, the ratio of the LP-EGR flow rate to the HP-EGR flow rate (total distribution ratio) - The flow rate of EGR needs to be measured individually.

An LP-EGR flow rate measuring device 50 is installed at the front end of the compressor 14 to measure the LP-EGR flow rate supplied to the intake air, and an HP-EGR flow rate measuring device 52 ) Is installed to measure the HP-EGR flow rate supplied to the intake air.

The LP-EGR flow rate measuring device 50 and the HP-EGR flow rate measuring device 52 may be a flow meter for measuring the flow rate of the fluid or indirectly estimating the EGR flow rate by measuring the pressure on the exhaust side, In the embodiment of the present invention, a carbon dioxide sensor is used as the LP-EGR flow rate measuring device 50 and the HP-EGR flow rate measuring device 52. Since the ratio of carbon dioxide in the atmosphere is extremely low, carbon dioxide contained in the intake air can be treated as being introduced from the EGR gas, so it is possible to measure the flow rate of the EGR gas or the EGR ratio in the intake air using the carbon dioxide sensor.

And the supercharging pressure of the air flowing into the engine 1 through the intake manifold through the supercharging pressure measuring means 60 is measured. The boost pressure measuring means 60 is for measuring the final boost pressure and should therefore be disposed at the rear end of the electronic supercharger 20. [ As the boost pressure measuring means 60, a known sensor such as a MAP sensor (Manifold Absolute Pressure sensor) may be used.

The above-described hardware configuration of the intake control device is controlled through the intake control unit 70, and the configuration thereof is schematically shown in Fig.

The intake control unit 70 includes map data in which the RPM of the engine 1, the boost pressure for the fuel consumption amount, and the target value of the total EGR flow amount are set. The RPM and the fuel consumption amount of the engine 1 indicate the operation region of the engine 1, that is, the engine speed and load, and the target values of the boost pressure and the total EGR flow rate are set for each point of the map data will be.

The intake control unit 70 controls the operation of the electronic supercharger 20 so as to satisfy the target values of the map data at the respective operating points of the engine 1, that is, the target values of the boost pressure and the total EGR flow rate, And the operation of the LP-EGR valve 34 and the HP-EGR valve 44, respectively.

As described above, the total EGR flow rate is determined by the LP-EGR valve 34 and the HP-EGR valve 34 so that the sum of the respective EGR gases measured by the LP-EGR flow rate measuring device 50 and the HP- -EGR valve 44, respectively. Here, since the HP-EGR flow rate measuring device 52 disposed at the rear end of the electronic supercharger 20 measures the EGR gas in the intake air into which the LP-EGR flow rate has already been introduced, the HP- It is possible to calculate the total EGR flow rate measured by the measuring device 52 by subtracting the LP-EGR flow rate measured by the LP-EGR flow rate measuring device 50 already.

However, it is not easy to meet the target of boost pressure together with the total EGR flow rate. The HP-EGR flow rate and the LP-EGR flow rate depend not only on the opening amounts of the HP-EGR valve 44 and LP-EGR valve 34, but also on the HP-EGR passage 42 and the LP- Is influenced by the pressure of the exhaust gas. If the final boost pressure is higher than the pressure of the exhaust gas in the HP-EGR passage 42, the HP-EGR gas flows backward. In the case of LP-EGR, since the exhaust gas pressure is higher than the atmospheric pressure, there is no such problem. However, since the back pressure fluctuation occurs at the rear end of the turbine 12 due to the influence of the supercharging degree, it is difficult to freely control the LP- .

Therefore, the intake control device of the present invention is configured to achieve the target value of the supercharging pressure by performing the two-stage supercharging as necessary only when necessary by using the electronic supercharger so as to more freely achieve the target supercharging pressure. That is, the turbocharger 10 supplements the supercharger by using the electronic supercharger, instead of operating the turbocharger 10 naturally without any operation according to the operating characteristics of the turbocharger 10, which can not be achieved by the turbocharger 10 alone .

Therefore, by using the electronic supercharger without changing the design of the turbocharger 10, it is possible to achieve a supercharger suited to the driving situation. Thus, according to various driving strategies, it is possible to improve the fuel efficiency, And the like can be easily satisfied.

Further, the target value data of the total EGR flow rate included in the map data may include a distribution ratio of the LP-EGR flow rate and the HP-EGR flow rate. This is to help the intake control unit 70 establish a more diversified operation strategy by reflecting the distribution ratio of the LP-EGR flow rate and the HP-EGR flow rate to satisfy the total EGR flow rate.

As described above, from the viewpoint of the response of the EGR system, the HP-EGR system has a high responsiveness and the LP-EGR system has a low responsiveness. In the LP-EGR system, since the pressure at the rear end of the turbine 12 is used as a driving force for recirculating the exhaust gas, the responsiveness is low. Also, the back pressure fluctuation at the rear end of the turbine 12 It is difficult to freely control the flow rate of the EGR gas.

On the other hand, the LP-EGR system does not affect the turbocharger 10 because it extracts the exhaust gas after passing through the turbine 12, and since the turbocharger 10 can use exhaust gas energy, Thereby improving the responsiveness of the charger 10, that is, improving the driving performance.

Therefore, in a situation where quick response to EGR gas supply is required, various strategies such as raising the HP-EGR flow rate and raising the ratio of LP-EGR flow when the turbocharger 10 needs quick response are easily established And the advantage of the present invention is that even in such a fine control, the supercharging pressure can be immediately responded to via the electronic supercharger.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. It will be possible. Accordingly, the scope of the present invention will be determined by the description of the claims and their equivalents.

1: Engine 10: Turbocharger
12: Turbine 14: Compressor
20: Electronic supercharger 30: LP-EGR device
32: LP-EGR passage 34: LP-EGR valve
40: HP-EGR device 42: HP-EGR passage
44: HP-EGR valve 50: LP-EGR flow rate measuring device
52: HP-EGR flow meter
60: supercharge pressure measuring means 70: intake control unit

Claims (3)

A turbocharger in which a turbine is disposed on an exhaust flow path extending from an exhaust manifold of an engine and a compressor is disposed on an intake flow path extending from the intake manifold;
An electronic supercharger disposed on a downstream side of the compressor of the turbocharger;
An LP-EGR passage connecting the rear end of the turbine and the front end of the compressor, and an LP-EGR valve disposed on the LP-EGR passage;
An HP-EGR passage connecting the front end of the turbine and a rear end of the supercharger; and an HP-EGR valve disposed on the HP-EGR passage;
An LP-EGR flow rate measuring device installed at a front end of the compressor to measure an LP-EGR flow rate supplied to the intake air;
An HP-EGR flow rate measuring device installed at a rear end of the supercharger for measuring a flow rate of HP-EGR supplied to the intake air;
A supercharging pressure measuring means for measuring supercharging pressure of the air flowing into the engine through the intake manifold; And
And a controller for controlling the operation of the supercharger and the operation of the LP-EGR valve and the HP-EGR valve so as to satisfy a target value of the map data, An intake control unit for feedback-controlling each operation;
And an intake control device of the dual loop EGR system. The method according to claim 1,
The target value data of the total EGR flow rate included in the map data includes a distribution ratio of the LP-EGR flow rate and the HP-EGR flow rate, and the intake control unit satisfies a distribution ratio of the LP-EGR flow rate and the HP- Wherein the operation of each of the LP-EGR valve and the HP-EGR valve is feedback-controlled so as to control the intake air amount of the internal combustion engine. The method according to claim 1,
Wherein the LP-EGR flow rate measuring device and the HP-EGR flow rate measuring device are carbon dioxide sensors. 2. An intake control device of an electronic two-stage supercharging system and a dual-loop EGR system.

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