Abstract:
A supercharging system for an engine includes: a cylinder block forming a combustion chamber; an intake manifold connected to the cylinder block to supply ambient air thereto; an exhaust manifold collecting exhaust gas discharged from the combustion chamber and guiding the same to the environment; a third supercharge path connecting an inlet of the intake manifold to the exhaust manifold; and an electric supercharger supplying compressed air to the exhaust manifold through the third supercharge path. Responsiveness of an engine is enhanced and stabilization of the engine is promoted.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims priority of Korean Patent Application Number 10-2013-0022419 filed Feb. 28, 2013, the entire contents of which application is incorporated herein for all purposes by this reference. 
       BACKGROUND OF INVENTION 
       [0002]    1. Field of Invention 
         [0003]    The present invention relates to a supercharging system for an engine, and more particularly, to a supercharging system for an engine capable of jetting air to an exhaust manifold by using an electric supercharger. 
         [0004]    2. Description of Related Art 
         [0005]    In a vehicle, generally, ambient air is introduced into the vehicle, mixed with fuel, and supplied to an engine, and the engine burns the mixture of air and fuel to obtain power required for driving the vehicle. 
         [0006]    Here, for combustion in the course of generating power by driving an engine, ambient air must be sufficiently supplied to obtain a desired output and combustion efficiency of the engine. Thus, in order to increase combustion efficiency and enhance an output of an engine, a supercharger or a turbo charger that pressurizes air for combustion and supplies the pressurized air is applied to a vehicle. 
         [0007]    The supercharger has a structure compressing air to be supplied to an engine by using pressure of an exhaust gas discharged from the engine. 
         [0008]    However, there is a limitation in compressing intake air with only pressure of exhaust gas and supplying the same to an engine according to a running situation of a vehicle, so recently, an electric supercharger that drives a compressor by using an electric motor to compress intake air and supplies the same is applied to a vehicle. 
         [0009]    The electric supercharger serves to secondarily jet air toward an exhaust manifold in order to enhance responsiveness of an engine in a turbo-lag interval before the turbo charger operates. 
         [0010]    In a system of secondarily jetting air toward an exhaust manifold by using an electric supercharger as mentioned above, there is a need to shorten a length of an air jetting flow channel to enhance responsiveness of an engine, and discharge supercharged air outwardly to stabilize the engine after air is secondarily jet. 
         [0011]    The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art. 
       BRIEF SUMMARY 
       [0012]    Various aspects of the present invention provide for a supercharging system for an engine having advantages of enhancing responsiveness of an engine by effectively jetting compressed air toward an exhaust manifold through a short flow channel by using an electric supercharger, and stabilizing the engine by discharging supercharged air outwardly after compressed air is jet toward the exhaust manifold. 
         [0013]    Various aspects of the present invention provide for a supercharging system for an engine, including: a cylinder block forming a combustion chamber; an intake manifold connected to the cylinder block to supply ambient air thereto; an exhaust manifold collecting exhaust gas discharged from the combustion chamber and guiding the same to the outside; a third supercharge path connecting an inlet of the intake manifold to the exhaust manifold; and an electric supercharger supplying compressed air to the exhaust manifold through the third supercharge path. 
         [0014]    The supercharging system may further include an air control valve installed in the third supercharge path in order to control supply of compressed air supplied to the exhaust manifold through the third supercharge path. 
         [0015]    The supercharging system may further include: a turbo charger compressing ambient air by using pressure of exhaust gas discharged from the combustion chamber and supplying compressed air to the combustion chamber; an intercooler cooling compressed air supplied from the turbo charger to the combustion chamber; a first supercharge path connecting the turbo charger and the intercooler; and a second supercharge path connecting the intercooler and the intake manifold, wherein the electric supercharger is connected to the second supercharge path. 
         [0016]    The supercharging system may further include: a bypass valve opening and closing the second supercharge path, wherein an inlet of the electric supercharger may be connected to the second supercharge path between the bypass valve and the intercooler and an outlet of the electric supercharger may be connected to the second supercharge path between the bypass valve and the intake manifold. 
         [0017]    The supercharging system may further include: a recirculation valve discharging compressed air within the third supercharge path to the outside. 
         [0018]    An intake path allowing ambient air to flow therein may be connected to the turbo charger, an air cleaner filtering foreign materials included in the ambient air may be installed in the intake path, an opening and closing valve opening and closing the intake path may be installed, a recirculation path allowing a partial amount of exhaust gas discharged through the exhaust manifold, to be introduced to the intake path may be connected to the intake path, an EGR cooler cooling exhaust gas may be installed in the recirculation path, and a control valve controlling exhaust gas introduced to the intake path through the recirculation path may be provided. 
         [0019]    The control valve and the opening and closing valve may constitute an integrated valve unit. 
         [0020]    A pressure sensor sensing pressure of the third supercharge path may be provided, and an engine control unit controlling the recirculation valve and the bypass valve by detecting pressure of the third supercharge path may be provided. 
         [0021]    When pressure of the third supercharge path sensed by the pressure sensor is higher than a pre-set pressure, the engine control unit may control the recirculation valve to be opened to discharge compressed air within the third supercharge path to the outside. 
         [0022]    The engine control unit may sequentially perform controlling the electric supercharger to be operated; controlling the air control valve to be opened and the bypass valve to be closed; controlling the air control valve to be closed and the bypass valve to be opened after a predetermined time elapses; controlling the electric supercharger to be turned off; sensing pressure of the third supercharge path by the medium of the pressure sensor; and controlling opening and closing of the recirculation valve according to pressure sensed by the pressure sensor. 
         [0023]    In the case of the supercharging system for an engine according to various aspects of the present invention, since the electric supercharger is disposed between the intercooler and the intake manifold, a length of an injection flow path of compressed air jetted to the exhaust manifold through the electric supercharger is shortened, enhancing responsiveness of an engine. 
         [0024]    Also, after compressed air is jetted through the electric supercharger, compressed air boosted by the electric supercharger is effectively discharged to the outside through the recirculation valve. Thus, the engine is stabilized, and when the electric supercharger is abnormally operated, stabilization can be secured. 
         [0025]    The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description, which together serve to explain certain principles of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]      FIG. 1  is a view illustrating a configuration of an exemplary supercharging system for an engine according to the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims. 
         [0028]    Referring to  FIG. 1 , an intake manifold  20  allowing air or a mixture of air and fuel to be introduced therein is connected to a cylinder block  10  forming a combustion chamber of an engine, and an exhaust manifold  30  for discharging exhaust gas generated after combustion in the combustion chamber from the cylinder block  10  is connected to the cylinder block  10 . 
         [0029]    A turbo charger TC is connected to the exhaust manifold  30  and the intake manifold charger  20 , respectively, in order to compress air by using pressure of exhaust gas discharged through the exhaust manifold  30  and supply the compressed air to the intake manifold  20 . 
         [0030]    Namely, a turbine constituting the turbo charger TC is connected to the exhaust manifold  30  and an impeller constituting the turbo charger TC is connected to the intake manifold  20 . 
         [0031]    Also, an exhaust path  40  is connected to the exhaust manifold  30  in order to induce exhaust gas introduced to the exhaust manifold  30  to the outside, that is, the environment. 
         [0032]    A catalytic converter is installed in the exhaust path  40  in order to reduce harmful components included in exhaust gas discharged through the exhaust path  40 . The catalytic converter may include a warm-up catalytic converter (WCC) and an under floor catalytic converter (UCC). 
         [0033]    A recirculation path  42  is connected to the exhaust path  40  between the two catalytic converters WCC and UCC in order to recirculate a portion of exhaust gas to the cylinder block  10 , and an exhaust gas recirculation cooler  50  is installed in the recirculation path  42  in order to reduce temperature of exhaust gas. 
         [0034]    An intake path  52  allowing ambient air to flow thereto is connected to the turbo charger TC, and the recirculation path  42  is connected to the intake path  52 , so the turbo charger TC compresses a portion of exhaust gas and ambient gas and supplies the same to the cylinder block  10 . 
         [0035]    In order to control exhaust gas introduced to the intake path  52  through the recirculation path  42 , a control valve  60  is installed in the recirculation path  42 . 
         [0036]    An opening and closing valve  70  for controlling opening and closing of the intake path  52  is installed in the intake path  52 , and the control valve  60  and the opening and closing valve  70  may be configured as an integrated valve unit. 
         [0037]    An air cleaner  80  filtering foreign materials included in ambient air and a bypass valve  80  are installed in the intake path  52 . 
         [0038]    An outlet of the turbo charger TC is connected to the intake manifold  20  through a supercharge path. 
         [0039]    An intercooler  90  is installed midway in the supercharge path in order to cool supercharged air discharged after being compressed by the turbo charger TC and supply the same to the intake manifold  20 . 
         [0040]    Namely, an outlet of the turbo charger TC and an inlet of the intercooler  90  are connected through a first supercharge path  92   a,  and an outlet of the intercooler  90  and the intake manifold  20  are connected through a second supercharge path  92   b.    
         [0041]    In order to compress air and supply compressed air to the intake manifold  20  or the exhaust manifold  30 , an electric supercharger  110  is installed in a second supercharge path  92  between the intercooler  90  and the intake manifold  20 . 
         [0042]    An inlet of the electric supercharger  110  is connected to the second supercharge path  92   b  between the intercooler  90  and a bypass valve  100 , and an outlet of the electric supercharger  110  is connected to the second supercharge path  92   b  between the bypass valve  100  and the intake manifold  20 . 
         [0043]    Also, a recirculation valve (RCV) for discharging compressed air boosted by the electric supercharger to the outside is installed in the second supercharge path  92   b  between the bypass valve  100  and the intake manifold  20 . 
         [0044]    The recirculation valve (RCV) also serves to prevent surge of a compressor of the turbo charger (TC) generated when an engine load is rapidly lowered after air is compressed and supercharged to the turbo charger (TC). 
         [0045]    In order to enhance responsiveness of the engine during a turbo-lag interval before the turbo charger (TC) operates, a third supercharge path  92   c  is provided to supply air compressed by the electric supercharger  110  to the exhaust manifold  30 . 
         [0046]    The third supercharge path  92   c  connects the second supercharge path  92   b  between the recirculation valve (RCV) and the intake manifold  20  to the exhaust manifold  30  to supply compressed air in the second supercharge path  92   b  to the exhaust manifold  30 . 
         [0047]    In order to control supply of compressed air through the third supercharge path  92   c,  an air control valve  120  is installed in the third supercharge path  92   c.    
         [0048]    Also, in order to sense air pressure within the second supercharge path  92   b,  a pressure sensor  130  is installed in the second supercharge path  92   b  between the bypass valve  100  and the intake manifold  20 . 
         [0049]    The pressure sensor  1330  is connected to an input terminal of an engine control unit (ECU) so that a pressure signal sensed by the pressure sensor  130  is input to an electronic control unit or the engine control unit (ECU). 
         [0050]    The electric supercharger  110 , the recirculation valve RCV, the bypass valve  100 , and the air control valve  120  are connected to an output terminal of the ECU, and operations thereof are controlled according to a control signal from the ECU. 
         [0051]    While a vehicle is running, the engine control unit (ECU) applies a driving signal to the electric super charger  110  during a turbo-leg interval before the turbo charger (TC) operates. 
         [0052]    When the electric supercharger  110  is driven, the recirculation valve (RCV) is maintained in an OFF state (in this state, the second supercharge path  92   b  is shut against the outside), and the bypass valve  100  is maintained in an OFF state in order to shut the second supercharge path  92   b  between the intercooler  90  and the intake manifold  20 . 
         [0053]    The electric supercharger  110 , driven upon receiving a driving signal from the engine control unit (ECU), allows ambient air to flow therein through the second supercharge path  92   b  between the intercooler  90  and the bypass valve  100 , compresses the same, and subsequently supplies compressed air to the second supercharge path  92   b  between the bypass valve  100  and the intake manifold  20 . 
         [0054]    When compressed air is supplied by the electric supercharger  110 , the engine control unit (ECU) applies a control signal to the air control valve  120  to open the third supercharge path  92   c.    
         [0055]    Accordingly, the compressed air, passing through the third supercharge path  92   c  and the air control valve  120 , is jet to the exhaust manifold  30 , and the compressed air jetted to the exhaust manifold  30  acts as an operating pressure on the turbo charger (TC), increases pressure of intake air, and supplies the same to the engine. 
         [0056]    In this manner, since compressed air is supplied to the exhaust manifold  30  through the short third supercharge path  92   c,  responsiveness of the engine is enhanced. 
         [0057]    Meanwhile, after the electric supercharger  110  is operated to jet air to the exhaust manifold  30  to stabilize an operation of the engine, namely, after a predetermined time has elapsed, the engine control unit (ECU) applies a control signal to the air control valve  120  to shut the third supercharge path  92   c  to prevent exhaust gas from flowing backward through the exhaust manifold  30 , a control signal to the bypass valve  100  to open the second supercharge path  92   b,  and the operation of the electric supercharger  110  is stopped by interrupting a driving signal of the electric supercharge  110 . 
         [0058]    Subsequently, the engine control unit (ECU) senses internal pressure of the second supercharge path  92   b  by the medium of the pressure sensor  130 , and when the sensed pressure is determined to be higher than a pre-set pressure, the engine control unit (ECU) applies a control signal to the recirculation valve (RCV) to open it, whereby compressed air within the second supercharge path  92   b  is discharged to the outside through the recirculation valve (RCV), releasing pressure in the second supercharge path  92   b.    
         [0059]    Of course, when pressure within the second supercharge path  92   b  is lower than the pre-set pressure, the recirculation valve (RCV) is maintained in an OFF state. 
         [0060]    The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.