The present application claims priority under 35 U.S.C. § 119 to German Patent Application No. 102 2004 037 773.1-26, filed Aug. 4, 2004, the entire disclosure of which is herein expressly incorporated by reference.
The present invention relates to a method for limiting the rotational speed of internal combustion engines with spark ignition.
German Patent Document DE 33 19 025 C2 describes a method and a device for limiting the rotational speed of internal combustion engines having spark ignition, whereby on reaching a first definable rotational speed value, the fuel mixture is made leaner and the ignition sequence is worsened and at a second rotational speed value, which is greater than the first rotational speed value, a switch is made to a much leaner fuel mixture.
In comparison with the known method, the method of the present invention has the advantage that the combination of a soft rotational speed limitation and a hard rotational speed limitation complies with demands for comfort while also complying with demands for an extremely sporty driving performance in vehicles having high-performance engines. In internal combustion engines having high-performance engines, reducing torque only through injection fade-out and delaying injection results in excessively high rotational speed amplitudes in the area of the desired maximum rotational speed, which is perceived as unpleasant by the driver. In contrast, limiting the rotational speed by regulating the throttle valve on the vehicle cannot be perceived directly by the driver with a very sporty driving style and for power measurements.
In accordance with the method of the present invention, the function of the hard rotational speed limitation is implemented in such a way that the duration of the cylinder fade-out and the interval of the fade-outs and/or the non-fade-out of the engine are applied in any way desired via a control unit. The duration of turning the injection on and off with or without ignition intervention can be adjusted in any way and at the same time is regulated via intervention involving the electric throttle valve.
Another advantage is obtained with the inventive control method due to the fact that the switching between a hard and a soft rotational speed limitation can be adjusted according to the desired driving performance. Thus, it is conceivable for the control to first trigger a hard rotational speed limitation and later to switch for several seconds to a soft rotational speed limitation or vice-versa. The background for such switching from hard and soft rotational speed limitation may be provided by the requirements of the engine and the catalytic converter. The change from a soft to a hard rotational speed limitation may be desirable when the driver is to receive feedback that he should shift to the next higher gear.
Another advantageous embodiment is possible with the inventive rotational speed limitation due to the fact that different maximum rotational speeds may be regulated for any period of time and for any gears. The driving performance of the internal combustion engine can thus be adapted even better to various requirements. All the variables to be controlled can, for example, be stored in a control unit and can be determined in the application.
The inventive method is depicted in the exemplary embodiment and is explained in greater detail in the following description.
The inventive triggering is explained in greater detail below with reference to the figures.
The input variables detected include, for example, the load, the temperature, the prevailing fuel consumption, the pressure and the position of the throttle valve. Based on the detected operating data of the internal combustion engine thus detected, the prevailing rotational speed in nact is determined in working step 11. Optionally, a predictive analysis of the rotational speed to be expected may also be performed. This means that a “predictive” rotational speed npredict is calculated on the basis of a prediction time which is programmable as a function of gear.
In parallel with operating step 12, the individual control variables for ignition, injection and throttle valve position and the prevailing gear are determined with the help of various stored engine characteristics maps, and the maximum allowed rotational speed nmax for this operating point is determined on the basis of the control variables.
The outputs of the operating step 11 and the operating step 12 are connected to decision step 13. Here the maximum allowed rotational speed nmax is compared with the prevailing (actual) nact rotational speed or optionally the predictively determined rotational speed npredict. If the prevailing rotational speed nact or the predictive rotational speed npredict is smaller than the maximum allowed rotational speed nmax, then the question nact≧nmax and/or the question npredict≧nmax would both be answered in the negative, and the method would return to the first operating step 11. In other words, there would be no need for action and the monitoring of the prevailing operating conditions and rotational speed would begin anew.
If the query 11 nact≧nmax or npredict≧nmax is answered in the affirmative, i.e., the maximum allowed rotational speed nmax is exceeded by the prevailing rotational speed nact or if the predicted rotational speed has occurred, then in a subsequent operating step 14 the respective intervention to limit the rotational speed is determined on the basis of the prevailing parameters.
In this case, a hard rotational speed limitation with support of the electric throttle valve and a soft rotational speed limitation interfere with one another or are activated in alternation depending on the requirements of the internal combustion engine.
The diagram depicted in
The diagram shown in
The intervention of a soft or hard rotational speed limitation may be specified for different drivers or driving styles in the control unit as needed. The change between the two variants of rotational speed limitation offers the advantage that the engine and the catalyst are protected by changing from hard to soft rotational speed limitation, whereas in changing from soft to hard rotational speed limitation the driver receives feedback that draws his attention to the fact that he should shift to the next higher gear.
The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.
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6098574 | Arakawa et al. | Aug 2000 | A |
6371081 | Hawkins et al. | Apr 2002 | B1 |
6581584 | Sato et al. | Jun 2003 | B2 |
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Number | Date | Country |
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33 19 025 | Nov 1984 | DE |
199 13 272 | Sep 2000 | DE |
101 41 600 | Mar 2003 | DE |
Number | Date | Country | |
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20060032480 A1 | Feb 2006 | US |