Patent Publication Number: US-8528331-B2

Title: Enhanced supercharging system and an internal combustion engine having such a system

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuing application of co-pending application Ser. No. 12/670,226 filed on Jan. 22, 2010, which is the 35 U.S.C. §371 national stage of International PCT/SE2008/050883 filed on Jul. 22, 2008, which claims priority to U.S. application Ser. No. 11/781,992 filed on Jul. 24, 2007. The entire contents of each of the above-identified applications are hereby incorporated by reference. 
    
    
     FIELD OF INVENTION 
     The present invention refers to a new, enhanced supercharging system for an internal combustion engine, and also to an internal combustion engine having such a system. 
     BACKGROUND OF THE INVENTION 
     Today there is a strong development going on in automotive industry in order to find systems for decreasing over all fuel consumption. There are many technical areas, which together make up for a good result. 
     One good way of improving internal combustion engine efficiency is to use some kind of supercharging device to increase intake manifold pressure in order to decrease the internal pumping losses. This in turn leads to decreased fuel consumption. It also makes it possible to downsize the engine without interfering with vehicle performance requirements. 
     There are several different supercharging devices available, but they can all be sorted to one of the following types: 
     From a vehicle drive shaft, such as for instance a crankshaft, mechanical driven superchargers
     Exhaust driven turbo superchargers   Electrical motor driven superchargers   

     In some applications more than one supercharging device may be used at the same engine. 
     JP published patent application No 2000-230427 refers to an internal combustion engine with a supercharger, which via a clutch adapted to connect and disconnect the engine and the supercharger. 
     WO 2004/025097 A1 discloses a method for operating an internal combustion engine having a turbocharger with a separate compressor driven via a belt-drive from the engine crankshaft, said compressor being connected to the inlet of the turbocharger for increasing the pressure of the intake air delivered to the turbocharger This means that the losses increase due to additional pressurized conduits between the separate compressor and the turbocharger, and also increased mechanical compressor losses at high motor speeds. 
     PURPOSE OF THE INVENTION 
     The purpose of the present invention is to combine all these different propulsion modes into one supercharging device in order to make benefit of the different properties associated with the different propulsion modes The purpose is also to provide a possibility of converting overflow energy from the exhaust gases to electric energy, that can be used to recharge the battery if required The supercharging device according to the invention shall be practically applicable on existing internal combustion engines and it shall be possible to propel the inlet supercharging device with all defined types of propulsion modes. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Hereinafter the invention will be further described with reference to schematically shown embodiments. 
         FIG. 1  is a schematic side view of an internal combustion engine equipped with a supercharging system according to the invention, 
         FIG. 2  illustrates schematically in block form a principal lay out for the supercharging system according to the present invention, 
         FIG. 3  shows schematically in a side view an embodiment of the supercharging system according to the invention, and 
         FIG. 4  is a further schematically shown embodiment of the supercharging system, according to the invention, 
         FIG. 5  shows in a view resembling to  FIG. 1  a modified embodiment of an internal combustion engine equipped with a supercharging system according to the invention, 
         FIGS. 6-16  illustrate schematically further alternative embodiments of the supercharging system according to the invention. 
     
    
    
     BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The proposed solution described in the drawing figures combines a mechanical supercharging system, an electrical supercharging/regenerating system and an exhaust gas propelled turbo supercharging system, which are arranged on a common shaft. This shaft in turn is connected by means of a one way clutch unit to the mechanically propelled shaft, coupled to any engine drive shaft. 
       FIG. 1  shows schematically an internal combustion engine  1  having an air intake manifold  2 , and an exhaust gas manifold  3 . In the embodiment schematically illustrated there are four air intake pipes intimating that the engine has four cylinders, although the number of cylinders can be higher as well as lower. The engine  1  has a crankshaft  4 , which is equipped with a pulley  5 . 
     A supercharging device  6  is attached directly to the engine block in a similar way that turbocharging systems are attached today. This turbocharging device  6  incorporates a turbine  7  and a compressor  8  arranged on a common shaft  9 , where the turbine is driven by the exhaust gases from the exhaust gas manifold  3 , and the co-rotating compressor impeller  8  is compressing ambient air which is sucked in via an aft filter  10 , The compressed aft is in a duct  11  via an intercooler  12  and a throttle,  13  introduced in the air intake manifold  2 , whereas the exhaust gases after having passed the turbine are evacuated via an exhaust gas conduit  14  with a catalyzer  15 . 
     The pulley  5  rotating with the crankshaft  4  of the engine, transfers via a belt drive  16  rotation to a shaft  17 , which via a one way clutch  18 , can be coupled to the shaft  9 , on which the turbine  7  and the compressor  8  are arranged, thus that the rotation of the crankshaft  4  can be transferred to the shaft  9  common for the compressor and turbine, in situations where the turbine has not reached its working area. 
     For regeneration of rotary power to electric power, the common shaft  9  is connected via a belt drive  19  to an electric machine  20 , a battery or the like. The engine also incorporates an engine brake valve  21  and a wastegate  22 . 
     For fitting a supercharging device as described to existing internal combustion engines it is of course necessary to design this device in such a way that it compiles with existing power conversion nodes, i.e. the exhaust gas intake has to be situated for corresponding to the exhaust manifold outlet and the mechanically driven power conversion node has to be located in line with existing outputs for auxiliary loads from the internal combustion engine. 
     The following technical advantages of the supercharging device as described can be identified, and which mostly arise from the possibility to use each separate sub-system in this concept at its best efficiency interval:
     No, or very low mechanical compressor losses at high engine speeds.   Regeneration of energy, to electric power, from the supercharging device, when it has its best efficiency.   The compressor shaft may help the turbine to reach its working area quicker,   One supercharging device, one axis, three different driving modes.   No losses due to additional pressurized pipes between compressor and turbine.   No turbo-lag.   Easy to implement on almost any of today&#39;s existing combustion engines.   Possibility to regenerate overflow power from the exhaust gases to electrical power via the electric motor/generator.   Possible to momentary assist the mechanical supercharging system by electrical drive if needed, i.e. during very low engine speeds or to maintain boost pressure during fast speed transients.   Gains in terms of engine room space.   

       FIG. 2  illustrates schematically in block form a principal lay out for the supercharging system according to the present invention, in which is shown a turbine  7  and a compressor  8  arranged on a compressor shaft  8   a . Via a clutch  123 , which for instance can be a one way clutch, this compressor shaft  8   a  can be connected to and disconnected from a ring  24  forming part of a planetary gear  25 , having planet wheels  26  connected to a planet wheel carrier and cooperating with a sun wheel  27 , which is fitted to a shaft  28  rotatably supported and provided with a pulley  29 , which via a transmission, such as a belt drive  16 , is connected to a pulley  5  arranged on a drive shaft of the engine, such as the crankshaft  4  thereof, or the like. The planet wheel carrier in turn is via a transmission  130 , such as a belt drive, connected to an shaft  131  of an electric motor  132 , which is controlled by means of a control electronics device  133 . 
       FIG. 3  and  FIG. 4  illustrate schematically two slightly differing embodiments of the supercharging device according to the present invention. 
     Thus,  FIG. 3  illustrates a turbine  7  connected via a shaft  9  to a compressor wheel  8 . The shaft  9  is supported in bearings  34 ,  34   a , and carries at its end, remote from the turbine  7  a pulley  31   a , which via a not shown transmission, such as for instance a belt drive is coupled to a not shown generator in order to recover excessive energy from the turbine. In this embodiment of the supercharging device, the shaft  9  can via a clutch  18 ,  230  be connected to and disconnected from a further shaft  28 , whereby the shafts  9 ,  28  when the clutch is in engaged position interconnects the two shafts as a common axis. This second shaft  28 , which is supported in a bearing  34  and is equipped with a planetary gear  25  for changing up the speed. At its opposite side this further shaft  28  carries a further pulley  29 , which via a (not shown) transmission, such as a belt drive, is connected to the crankshaft or any other driving shaft of the combustion engine for driving the compressor  8  before the turbine has reached its working speed. 
     In  FIG. 4  is shown another embodiment of a supercharging device which is slightly different from that as shown in  FIG. 3 . 
     In this embodiment of a supercharging device according to the invention there is like in  FIG. 3  provided a shaft  9  carrying a turbine  7  and a compressor  8 , and which shaft is journalled in rolling bearings  34 , and plain bearing  34   a . The shaft  9  is connected to the ring  24  of a planetary gear  25  which has an opposite shaft  28  coupled to the planet wheels of the planetary gear  25 . At a short distance from the planetary gear the shaft  28 , which forms a continuous axis with the shaft  9 , is equipped with a pulley  31   a , which via a not shown transmission, such as for instance a belt drive is coupled to a not shown generator. After that pulley  31   a  there is provided a further shaft, which via a clutch  18  can be connected to and disconnected from the shaft  28 , and this further shaft carries a further pulley  29 , which via a (not shown) transmission, such as a belt drive, is connected to the crankshaft or any other driving shaft of the combustion engine. 
       FIG. 5  shows schematically an embodiment of an internal combustion engine  1  having an air intake manifold  2  with four air intake pipes, and an exhaust gas manifold  3 , having four exhaust gas pipes for the four cylinders of the engine. The engine  1  has a crankshaft  4 , which is equipped with a pulley  5 . 
     Attached to the engine block is a supercharging device  6 , incorporating a turbine  7  and a compressor  8  arranged on a common shaft  9 . The compressor  8  has a compressor shaft  8   a  projecting in the opposite direction to the common turbine/compressor shaft  9 . The turbine is driven by exhaust gases from the exhaust gas manifold  3 , and the impeller of the co-rotating compressor  8  is compressing ambient air which is sucked in via an air filter  10 . The compressed of is in a duct  11  via an intercooler  12  and a throttle  13  introduced in the air intake manifold  2 , whereas the exhaust gases after having passed the turbine are evacuated via an exhaust gas conduit  14  with a catalyzer  15 . 
     The pulley  5  rotating with the crankshaft  4  of the engine, transfers via a belt drive  16  rotation to a shaft  17 , which via a clutch unit  18 , can be coupled to an electric machine  20 , which in turn is coupled to a ring gear wheel  24  of a planetary gear  25  with planet gear wheels  26  and a sun gear wheel  27  connected to the compressor shaft  8   a . In this manner the shaft  9 , on which the turbine  7  and the compressor  8  are arranged, thus can transfer the rotation of the crankshaft  4  to the shaft  9 , in situations where the turbine has not reached its working area. 
     The engine also incorporates an engine brake valve  21  and a wastegate  22 . The brake valve,  21  is controlled by way of a control box  23 , which based on different engine behavior parameters, will operate for maintaining the rotational speed of the turbine so high as possible in order to avoid dangerous pressure increase at the exhaust side. 
       FIGS. 6 to 16  represent alternative versions of the layout of the supercharging device according to the invention shown in schematic form, whereby the schematic representation according to  FIG. 6  illustrates the main components of the embodiment according to  FIG. 5 , i.e. the turbine  7  is driven by the exhaust gases from the engine  1 . 
     The compressor  8  is arranged on the same shaft as the turbine  7 , and the engine crank shaft  4  drives via a transmission  16  a pulley which via a freewheel/clutch  18  is connected to a shaft of an electric machine  20  having a working speed of about 20000 rpm or more. Between the electric machine,  20  and the compressor shaft  8  is provided a planetary gear  25 . 
     The embodiment illustrated in  FIG. 7  differs to that according to  FIG. 6  in that the planetary gear  25  is positioned nearest to the clutch  18  and the electric machine  20  is positioned outside the clutch  18 . 
     In  FIG. 8  is shown an embodiment wherein the clutch  18  is positioned between the crank shaft  4  and the transmission  16 , whereas the electric machine  20  is connected to the ring gear wheel of the planetary gear  25 . 
     The embodiment shown in  FIG. 9  corresponds to the embodiment according to  FIG. 7 , with the exception that the electric machine is connected to the crank shaft  4 , via the clutch  18  and an additional transmission  16   a.    
       FIG. 10  shows an embodiment where the electric machine  20  is positioned between the turbine  7  and the clutch  18 , whereas the planetary gear  25  is positioned between the clutch  18  and the compressor. 
       FIG. 11  shows a further alternative embodiment where the turbine  7  and the compressor are interconnected via a planetary gear  25 , whereas the cutch  18  is connected between the crank shaft  4  and a transmission  16  driving the electric machine. In this embodiment the planetary gear thus is integral with the turbo chamber housing. 
     In  FIG. 12  is illustrated a mechanical embodiment where a first planetary gear  25  is positioned between the turbine  7  and the compressor  8 , whereas a second planetary gear  25   a  and a clutch  18  are positioned between the engine crank shaft and the electric machine  20 . 
       FIG. 13  illustrates an electromechanic solution, where the turbine  7  drives a generator  28 , which via a high-voltage connection feeds an electric machine  20 , A clutch  18  is provided between the electric machine  20  and a pulley for the transmission  16 , and between the pulley and a compressor  8  is provided a planetary gear  25  The rotary speed of the generator  28  is preferably about 100 000 rpm, whereas the electric machine has preferably a rotational speed of about 20 000 rpm. 
     In  FIG. 14  is illustrated how the turbo shaft  9  interconnecting the turbine  7  and the compressor  8  is positioned in a closed housing with the turbo shaft floating in a magnetic field. The solution is equipped with magnetic clutches  30  and gas seals  31 . A gear  32  is provided for transferring power from a first planetary gear  25  to a second planetary gear  25   a.    
       FIG. 15  illustrates a hybrid transmission for high-voltage with a common shaft  9 , and a high-speed electric motor connected directly to the turbine shaft and with a high-voltage battery package  33  and a high-speed, high-voltage electric machine  20   b.    
       FIG. 16  finally illustrates an embodiment rather like the one according to  FIG. 15 , but where the electric motor surrounding the turbine shaft is connected to any part of the planetary gear and with a voltage of the battery pack  33  of 600V, and the electric machine  20 ,  20   c  has a voltage of 600V. 
     DETAILED DESCRIPTION OF THE INVENTION 
     For easier description of the combined operation of this device the following sub systems are defined. 
     Turbo Charged System 
     Turbo charging means good efficiency when activated, but is dependent on high rotational speed for the exhaust gases to have enough power to propel the turbine fast enough to build up substantial intake manifold pressure. 
     Turbo charging has one major advantage in comparison to all other super charging systems, as it uses overflow energy in the exhaust gases to charge the intake manifold air. 
     By doing so no extra fuel is consumed in order to build up a good intake manifold pressure. The principle intake manifold pressure as a function of rotational speed has the following appearance: 
     Super charging means increased intake manifold pressure from low rotational speeds and a proportional increase of intake manifold pressure coupled to the rotational speed. Thus at higher rotational speed the efficiency of the supercharger becomes very poor due to high internal friction and heat losses, The principle intake manifold pressure as a function of rotational speed has the following appearance: 
     Electrical Super Charged System 
     Electrical super charged systems work in the same way as mechanically ones but with the advantage that they provide the possibility to control the intake manifold pressure to a given level by providing power when it&#39;s needed but also to regenerate power from the exhaust gases when possible, 
     Existing Power Electronics Monitoring Systems 
     Algorithms for energy management are necessary to be able to regenerate power into the electric system of the vehicle. Systems for this are already developed in many vehicles of today. These systems are designed to keep track on the present auxiliary loads as well as monitoring the battery status. If there is a need for the battery to be recharged and power is available due to the fact that not all auxiliary systems are used, the system may raise the generator load voltage, to start recharging the system. 
     The algorithms can be reconfigured so that it in addition to there present application also regenerates the power provided from this supercharging device into electric power when the battery is not fully charged. By doing so for example during high-way driving the electric system would be better prepared for start-stop applications where a fully charged battery is essential for a good start-stop operation. 
     In order to decide how and when the electric machine, should act new algorithms are needed to support the regenerating mode. By using existing hardware already in production, such as rpm-sensors, pressure and flow sensors together with modifications of existing electric monitoring systems, this could be done. 
     Power split and Defined Propulsion Modes in order to clarify the different propulsion modes of this new invention the following power conversion nodes have been defined: 
     
         
         A: Chemical power (flow, pressure)=&gt;Mechanical power (rotational speed, Torque) B: Mechanical power (rotational speed, Torque)=&gt;Chemical power (flow, pressure) C: Generative: Electrical power (I 1  U)=&gt;Mechanical power (rotational speed, Torque) 
         Regenerative: Mechanical power (rotational speed, Torque)=&gt;Electrical power (I 1  U). 
       
    
     SUMMARY 
     This invention provides a relatively easy way of reducing over all fuel consumption by combining already existing systems in a new way. If this invention could be combined on an engine equipped with a start-stop system this would further “boost” this system as well by increasing the amount of times one can start the engine before the electronic monitoring system (GEM) has to step in and shut down the start-stop application to avoid battery depletion. 
     The invention is not limited to the embodiments schematically illustrated in the drawings and described with reference thereto, but variants and modifications are possible within the scope of the appended claims. 
     The transmissions described have been illustrated as belt drives, but any type of appropriate transmission units can be used. The clutch units mentioned can be mechanical one way clutches of any appropriate type, although electric clutches, viscous couplings and the like are also possible.