Patent Application
20090025696
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.
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:
i) From a vehicle drive shaft, such as for instance a crankshaft, mechanically driven superchargers
ii) Exhaust gas driven turbo superchargers
iii) 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.
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.
Hereinafter the invention will be further described with reference to schematically shown embodiments.
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, where the two later are attached on a common shaft. This shaft in turn is connected by means of any type of clutch unit to the mechanically propelled shaft, coupled to a vehicle drive shaft, such as for instance the engine crankshaft.
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 air filter 10. The compressed air 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 transmission 16, such as for instance a belt drive, rotation to a shaft 17, which via a clutch unit 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 transmission 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 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, such as for instance the belt drive 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:
Thus,
In
In this embodiment of a supercharging device according to the invention there is like in
For easier description of the combined operation of this device the following sub systems are defined.
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.
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's needed but also to regenerate power from the exhaust gases when possible.
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 they in addition to theres 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 example 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.
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)=>Mechanical power (rotational speed, Torque)
B: Mechanical power (rotational speed, Torque)=>Chemical power (flow, pressure)
C: Generative: Electrical power (I, U)=>Mechanical power (rotational speed, Torque)
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 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.
