The present invention relates to a method, in a supercharged combustion engine in a vehicle, during forward travel of the vehicle, of regulating geometric changes in the supercharge system of the engine which promote changes in the boost pressure of the engine.
The invention also relates to a vehicle having a supercharged combustion engine with electronic control members controlling the supply of fuel and air to the combustion chamber of the engine.
In previously known supercharge systems for combustion engines, geometric changes in the systems, which promote changes in the boost pressure of the engine and/or exhaust-gas back pressure, are regulated instantaneously and internally within the engine, i.e. only after a change in the operating condition of the engine has been initiated. This leads to delays in the regulation owing to the time constants for emptying or pressurizing the pipe system of the engine, which can be large in volume. It is generally known, for example, that with present-day regulation it is not possible to avoid a so-called “turbo lag” in a turbocharged engine, i.e. a certain delay from the driver giving gas to the pick-up in torque. When a gearshift is made in an automatic gearbox to an engine having a turbo compressor, in which the boost pressure is regulated by regulating the exhaust-gas flow to the turbine with the aid of a shunt valve, a so-called “waste gate” valve, this valve is opened for a fall-off in torque based on engine-internal control independent of information on transients (for example gearshift) in the drive train. Typically, it is opened when the boost pressure exceeds a predetermined threshold value and is closed when the boost pressure falls below another predetermined threshold value. An early opening has a positive effect upon fuel consumption, whilst an early closing has a positive effect upon the response of the engine. A timely adjustment of the boost pressure in advance of a transient also has a positive effect upon the engine compression braking performed when an upward gearshift is made.
An object of the present invention is to produce a method of controlling geometric changes in the supercharge system of the engine, for example of controlling a waste-gate valve, so that changes in the boost pressure of the engine can be matched in advance to a future course of events, instead of, as in the current situation, only being controlled instantaneously internally within the engine.
This is achieved according to the invention by calculating the future road resistance of the vehicle, by estimating the time period to a future transient in the operating condition of the engine and by making, during this time period, necessary geometric changes in the supercharge system of the engine so as to optimize at least the response of the engine when the transient arises.
When a gearshift is made, a better response than previously can thereby be achieved, for example, by closing the waste-gate valve before the boost pressure has had time to fall (or the gearshift is wholly completed), so that the boost pressure has time to be built up to the necessary level to provide immediate response, upon a subsequent pick-up in torque, as soon as the gearshift operation is concluded.
The invention is based on the fact that electronic control members controlling said geometric changes, for example re-setting of a waste-gate valve, have information on when a future transient, for example gearshift, will take place. This information is founded on information on future changes in the road resistance of the vehicle. The invention is herein based upon the technique described in patent application SE 01 03629-2. With inputted parameters and hence knowledge of at least road gradient and vehicle gas pedal position, but also possibly covering engine, turbo and transmission characteristics, the control members are here designed to elect when a future gearshift will be made according to a chosen gearshift strategy. Information on future road resistance can herein be obtained by the use of GPS equipment and electronic maps containing stored data on the topography of the surroundings. For a more detailed description of the technique for identifying the surroundings of the vehicle, reference is therefore made to the abovementioned patent application.
A motor vehicle of the type stated in the introduction is characterized according to the invention in that the control members are designed, during forward travel of the vehicle, on the basis of input information on at least road gradient and gas pedal controls position, to estimate future road resistance and the time period to a future transient in the operating condition of the engine and to control geometric changes in the supercharge system of the engine during said time period so as to optimize the response of the engine when the transient arises.
The invention is described in greater detail below with reference to illustrative embodiments shown in the appended drawing, in which:
a shows a diagrammatic representation of a combustion engine and transmission with a first embodiment of a turbo compressor;
b shows a second and
In
In
In the control unit 3, the forward travel of the vehicle is stored in the form of the increase in engine speed as a function of time, which in
Within the time period marked in
If the engine is provided with a compression brake device, for example of the type shown and described in EP 0 458 857 B1, to which reference is made for a more detailed description of the design and functioning of a type of compression brake, the boost pressure is controlled during the time period, as an upward gearshift is made in the gearbox, in order to optimize the engine braking torque.
Number | Date | Country | Kind |
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0301198-8 | Apr 2003 | SE | national |
The present application is a continuation patent application of International Application No. PCT/SE2004/000400 filed 18 Mar. 2004 which was published in English pursuant to Article 21(2) of the Patent Cooperation Treaty, and which claims priority to Swedish Application No. 03011 98-8 filed 24 Apr. 2003. Said applications are expressly incorporated herein by reference in their entireties.
Number | Date | Country | |
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Parent | PCT/SE04/00400 | Mar 2004 | US |
Child | 11163593 | Oct 2005 | US |