Internal-combustion engines – Combustion chamber means having fuel injection only – Combustible mixture stratification means
Reexamination Certificate
2001-09-17
2003-03-11
Mohanty, Bibhu (Department: 3747)
Internal-combustion engines
Combustion chamber means having fuel injection only
Combustible mixture stratification means
C123S406230, C123S406240, C123S436000
Reexamination Certificate
active
06530358
ABSTRACT:
The invention relates to a method for controlling an internal combustion engine with interventions in at least one manipulated variable.
BACKGROUND OF THE INVENTION
In the context of controlling internal combustion engines it is known to determine a setpoint torque which is to be generated by the internal combustion engine. Various manipulated variables of the internal combustion engine can be set in combination in such a way that the setpoint torque is generated in the steady-state condition.
In this context, reference is made, as prior art, by way of example to DE 198 03 387 C1 from which it is known to assign priorities to various torque requirements in such a way that ultimately a setpoint torque is determined which is then to be set. These various torque requirements relate, on one hand, to a desired torque determined by the driver of the vehicle and to setpoint torques which are predefined by subsystems. These subsystems can be, for example, a control for controlling distances from other vehicles, a cruise control, a controller for vehicle movement dynamics and/or a transmission controller.
DE 198 07 124 A1 discloses how a standard interface is provided to the effect that a setpoint for the internal combustion engine is predefined centrally. Furthermore, various procedures are described in said document which describe interventions in manipulated variables of the internal combustion engine during which the setpoint torque can be set with different speeds. For example, a setting of the setpoint torque which is optimized with respect to the efficiency of the internal combustion engine is made by setting the load. Furthermore, alternatively or additionally the ignition angle can be adjusted if, for example, the setpoint torque is to be set quickly.
DE 43 15 885 C1 and DE 196 15 542 C2 disclose various procedures for generating torques which are determined by defined interventions in the manipulated variables of the internal combustion engine.
It is the object of the present invention to provide a method of controlling an internal combustion engine by which the torque to be generated by the internal combustion engine can be set as precisely as possible.
SUMMARY OF THE INVENTION
In a method for controlling an internal combustion engine by means of interventions in at least one manipulated variable of the internal combustion engine, a setpoint torque or work which is to be performed is determined at the crankshaft of the internal combustion engine, wherein, with respect to a first variable as work which is to be performed or a setpoint torque to be provided, a corresponding setpoint quantity of heat is determined taking into account the instantaneous actual efficiency, with respect to which at least one associated manipulated variable is set in accordance with the value of the set-point quantity of heat, and, for precise setting of the torque, the actual quantity of heat also being sensed, a setpoint efficiency being determined from the actual quantity of heat taking into account work which is to be performed or a setpoint torque which is to be provided, this can correspond to the first variable or to another variable which is formed as a setpoint torque or work which is to be performed at the crankshaft, and at least one manipulated variable of the internal combustion engine is set approximately simultaneously in accordance with a setting of the setpoint efficiency.
When controlling the internal combustion engine, it is not necessary to provide an absolutely precise setting of the torque under all operating conditions. Instead, by using the method according to the invention, it is possible to perform an exact setting under certain operating conditions under which a predefined torque is to be set in a precise way. This relates, for example, to torque values required by safety-critical systems such as a traction controller or operating conditions such as torque switching. It is then possible to provide a rapid and precise setting of the correct torque by intervening in at least one manipulated variable which influences the efficiency. In a direct-injection engine or a diesel engine, such a rapid and precise setting of the torque can also be performed by means of the supplied quantity of heat in the form of the amount of fuel supplied. If a torque which has been defined by the driver is to be set, it is also possible to tolerate deviations within certain limits so that during the control an optimum efficiency can then be set in order to optimize emissions and/or save fuel.
The manipulated variable may be set in the next working cycle or, if appropriate, even in the current working cycle.
The procedure is therefore based, during the precise setting of the torque, on determining, in one working cycle, the work which is to be performed at the crankshaft (the setpoint torque). The setpoint quantity of heat for this working cycle is determined in accordance with the current efficiency which results from the setting of the manipulated variables of the internal combustion engine in this working cycle. This setpoint quantity of heat can be set by means of corresponding manipulated variables such as the volumetric efficiency (during homogeneous operation in a spark ignition engine) or the quantity of fuel injected (in stratified charge mode, in a diesel engine or a spark ignition engine). Furthermore, the actual quantity of heat is sensed. As a result, a possible deviation can be detected.
Settings of manipulated variables which influence the efficiency are then obtained by virtue of the fact that a setpoint efficiency is determined from the actual quantity of heat and from the work which is to be performed. This setpoint efficiency can then be set approximately simultaneously by means of a manipulated variable or an interaction between a plurality of manipulated variables. For example, the ignition time can be adjusted in order to limit the efficiency, or the valve control can be varied. It is also possible here to initiate an intervention in the manipulated variables with an intervention in the setting of the ignition time because this manipulated variable can be influenced on a short-term basis. The intervention in this manipulated variable can then be combined with an intervention in the valve control. The setting of the valve control cannot be influenced in such a short-term fashion as the setting of the ignition time. A combined intervention can, for example, give the appearance that interventions have been carried out both in the setting of the ignition time and in the setting of the valve control. As the influence of the intervention in the valve control increases, the adjustment of the ignition time can be reversed when the intervention in the valve control appears to take effect, taking into account the system setting times.
The first variable can in turn be used in the calculation of the setpoint efficiency, as it is explained, for example, below in conjunction with the switching of operating modes such as, for example, a cylinder shut off or a change from stratified charge mode into homogeneous mode in a direct-injection spark ignition engine. However, a different variable can also be used, which is likewise determined as the setpoint torque or work which is to be performed at the crankshaft, as is explained, for example, below in conjunction with the setting of a reserve torque in which the setpoint quantity of the heat, which is set is increased in comparison with the setpoint torque, which is to be set at a given time, and is “corrected” by means of a corresponding setting of the efficiency, in order to obtain a better setting speed when a relatively large torque change is desired.
The work which is to be performed at the crankshaft can be determined taking into account various influencing factors. It is possible, for example, to take into account torque requirements of assemblies of the internal combustion engine. Furthermore, inert masses of the internal combustion engine itself can also be taken into account. Furthermore, the driver's request with respect to a pos
Kalweit Dieter
Merkle Sven
Panten Andrej
Roulet Tobias
Bach Klaus J.
Daimler-Chrysler AG
Mohanty Bibhu
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