JP3676835B2 - Control device for individual cylinder fuel injection - Google Patents

Description

[0001]
[Industrial application fields]
The invention relates to a control device for individual cylinder fuel injection in an internal combustion engine, or more precisely, of a plurality of cylinders in order to reduce the torque acting on the wheels of an automobile in which the internal combustion engine is installed. It relates to such a control device which temporarily interrupts fuel injection in at least one.
[0002]
[Prior art]
An example of a conventional control device is “Traction Control (ASR) Using Fuel Injection Suppression—Cost Effective Method of Engine Torque Control” (“Traction Control (ASR) Using Fuel-Injection Suppression—A Cost Effective Method”). of Engine-Torque Control "), which is known from a paper outside Boning, which has been published since 1992 in SAE Technical Papers 920641 (SAE Technical Paper Series 920641). This control device is due to a change in ignition timing and because at least one injector for one cylinder is temporarily denied a signal for fuel injection, so that no combustion occurs in the associated cylinder. Drive torque control is performed. The cited paper specifically deals with a special method for shutting off the fuel supply of different cylinders at each time.
[0003]
It should be pointed out that in connection with the present invention it is immaterial whether only one cylinder is temporarily rejected with the flammable mixture or whether this applies to several cylinders simultaneously. It is also immaterial whether only one individual cylinder or several predetermined cylinders are affected by such means, or whether all cylinders of an engine experience such intervention in a repetitive order. .
[0004]
The operation of the known control device is a rich mixture, ie a mixture containing more fuel than corresponding to the stoichiometric composition required for complete combustion of all components. When it is being operated with care, problems arise. Operation with a rich mixture exists, for example, at full load or when the ignition timing is delayed to resist knocking or to reduce drive torque. If ignition is delayed, the mixture is still combusting outside the cylinder, so that the temperature of the exhaust system is unacceptable unless the mixture is enriched for cooling purposes. Will rise.
[0005]
If one cylinder is no longer being fueled and the other is receiving a rich mixture, the exhaust system will use excess air and a rich mixture available for the combustion process from cylinders that are not receiving fuel. Has excess fuel from the cylinder operated at This introduces the risk of overheating of the exhaust system, in particular the catalyst.
[0006]
[Problems to be solved by the invention]
The invention provides for an internal combustion engine even when the internal combustion engine is operated with a rich mixture and the supply of fuel to one cylinder is interrupted and then resumed for control of the drive torque exerted on the wheels. It is an object of the present invention to provide a control device for fuel injection of individual cylinders in an internal combustion engine, which is configured to prevent post-combustion with this catalyst.
[0007]
[Means for Solving the Problems]
The control device according to the present invention is configured not to immediately interrupt the supply when a stop of the fuel supply to the cylinder is requested by the drive torque control system in an operating condition with a rich fuel mixture. Characterized by a supply control system. Instead, it initially supplies the engine with a stoichiometric or lean mixture for the waiting period. The fuel supply to one cylinder is cut off only after this waiting period has elapsed. This waiting period can be quite short as the exhaust mixture is moved through an exhaust system such as an essentially closed column. That is, the exhaust gas with excess fuel will be present for a fairly long period of time, e.g. the catalyst will be mixed with the exhaust gas with excess air, so that the combustion process is started in the catalyst There is no reason to fear that. Such mixing of the old rich exhaust gas portion with the new lean exhaust gas portion can only be a concern within a period of about 10 microseconds. The length of the waiting time is determined accordingly. It should be noted here that the length must be such that the conditions for torque reduction output by the drive slip control system can be realized as quickly as possible. It is preferably set as a function of the current value of the specified operating parameter of the internal combustion engine.
[0008]
When the interruption of fuel supply to one cylinder has to be terminated, this is done in the reverse direction with a corresponding waiting time. That is, after at least one cylinder is turned off and the operation is very weak overall, this operation is not immediately switched to a rich mixture, but the engine is not stoichiometric or lean during the waiting period. It can be operated using a simple air-fuel mixture. The lean mixture in the mentioned case is only very slightly lean to prevent a substantial proportion of oxygen and fuel mixing that occurs with the previous or subsequent rich mixture. In order to be more cautious of such mixing, it is advantageous to perform a sloped transition without a sudden transition from rich to lean or vice versa. However, abrupt transitions can also be made if the waiting time is chosen for this purpose to be somewhat longer than in the case of a sloped transition.
[0009]
【Example】
FIG. 1 shows a control device 11 for an internal combustion engine 10 that transmits driving force to the rear wheels RHR and RHL. The control device 11 includes an interruption designation device 12, a delivery control system 13, and an air-fuel mixture control system 14. The suspension designation device 12 receives signals SHR and SHL from wheel rotation speed sensors attached to the respective rear wheels. In addition, the interruption designation device 12 obtains corresponding signals SVR and SVL from two wheel rotation speed sensors assigned to each of the front wheels of the automobile. Based on these wheel rotation speed signals, the interrupt designation device determines whether there is excessive slip of the driven rear wheel. As soon as it determines this presence, it emits a signal indicating that the fuel supply to at least one cylinder must be shut off. However, this signal does not go directly to the mixture control system 14 but goes to the delivery control system 13 as in the case of a normal control device that performs drive torque control by the engine torque control system. The system 13 ensures that when the engine is currently in full operation, it is first switched to stoichiometric operation before the at least one cylinder is turned off, in a manner further described below. The mixture control system 14 emits an injection signal to the injection devices 15.1 to 15.4 in a manner known per se.
[0010]
In this embodiment, the delivery control system 13 is configured to perform the functions described with respect to FIG.
[0011]
After starting the control device 11, the interruption designating device 12 determines in a usual manner in step S 1 whether the fuel supply to at least one cylinder has to be interrupted. If this is negative (n), a jump is made to step S6 where it is checked whether the fuel supply has to be resumed. However, if an interruption is necessary, step S2 asks (after step S1) whether the engine is currently operating heavily. If this is not the case, a direct transition to step S5 takes place, in which the fuel supply to at least one cylinder is interrupted. However, if the rich operation is present, step S3 are switched to stoichiometric operation for all the cylinders, the time measurement is started for the progress of the waiting time t W. Next, an inspection is performed to see if the waiting time has elapsed (S4). As soon as this is affirmative, the aforementioned step S5 is reached and the fuel supply to at least one cylinder is shut off. The previously described step S6 checks whether the fuel supply has to be resumed next. If this is negative and the interrupt does not need to be changed, steps S1 and S6 are repeated. When it is finally found that the fuel supply has to be resumed (after step S6), step S7 is reached, this time when rich operation is required or the operating conditions for the engine 11 are in between Ask whether the modified operation is no longer needed. If the latter is true, step S10 is reached, in which all cylinders are again operated with the required mixture, in this case a stoichiometric or lean mixture. On the other hand, if the rich operation is required, at least one cylinder is shut off is caused to return to the stoichiometric operation, and the measurement of the progress of the waiting time t W is started anew. As soon as this waiting time determined in step 9 has elapsed, the aforementioned step S10 is reached, in which all cylinders are operated with the required mixture. The described procedure is then repeated from step S1.
[0012]
In this example, the system suddenly switched from a rich mixture to a stoichiometric mixture and vice versa. However, in each case, a gradual transition can also take place, for example within a period of 20 to 40 milliseconds. The waiting time is typically about 2 to 3 times longer, but the quoted time is highly dependent on the operating conditions of the engine, i.e. in particular on its rotational speed and load, and also on the overall structure of the exhaust system. If the exhaust system is configured such that mixing between the old exhaust gas and the new exhaust gas is very unlikely, the quoted time can be selected to be very short. On the other hand, if the controller is used for an internal combustion engine with an exhaust system where such mixing can occur even after several hundred milliseconds under adverse operating conditions, the latency to these adverse operating conditions Must be chosen to be correspondingly longer.
[0013]
In an embodiment, the respective waiting times for the transition to injection interruption and for the transition to rich operation are the same. However, the control system for an engine with an exhaust system that has different time effects on the one hand on the one hand between the old rich mixture and the new lean mixture and on the other hand the old lean mixture and the new rich mixture. If is operated, a correspondingly different waiting time is advantageous.
[0014]
【The invention's effect】
When a rich mixture and a lean mixture are mixed with each other in the exhaust system, such mixing leads to combustion, thus leading to an undesirable temperature rise in the exhaust system, particularly the catalyst. According to the present invention, such mixing is prevented.
[0015]
According to this invention, even when the internal combustion engine is operated with a rich air-fuel mixture and fuel supply to one cylinder is interrupted for the control of the driving torque exerted on the wheels and then restarted, Post combustion with the catalyst of the internal combustion engine is prevented.
[Brief description of the drawings]
FIG. 1 is a principle representation of a control device for individual cylinder fuel injection in an internal combustion engine according to the invention.
FIG. 2 is a flowchart for explaining functions of the control device in FIG. 1;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Internal combustion engine 11 Control apparatus 12 Interruption designation apparatus 13 Delivery control system 14 Mixture control system

Claims (3)

A control device ( 11 ) for individual cylinder fuel injection in an internal combustion engine ( 10 ),
Interruption designation device (12) configured to determine when fuel injection to at least one cylinder is interrupted and must be resumed as a function of operating parameters of the vehicle in which the internal combustion engine is operated And
Supply injection signals to all of the injectors (15.1 to 15.4) assigned to each cylinder, such that the specified air / fuel ratio is achieved for each cylinder. mixture control system which is configured to inject fuel into the device (15.1 to 15.4) and (14),
A delivery control system (13) configured to function as follows when a rich mixture must be set without cylinder interruption, i.e.
(A) If the interrupt designation device provides the delivery control system with a signal indicating that fuel injection must be interrupted for one cylinder, the system will first specify the injector with a designated waiting period. The injection signal is supplied during a period of time so that all cylinders are operated with a stoichiometric or lean mixture, and when the waiting period has elapsed, the system applies the injection to one cylinder. Continue to supply the injection signal to interrupt the signal and set the stoichiometric or lean mixture to the other injection devices;
(B) If the interrupt designator supplies the delivery control system with a signal indicating that fuel injection must be resumed for one cylinder, the system is also initially interrupted for injection. the injection device and the other injector relative to the cylinder and, when supplying an injection signal for setting the stoichiometric or lean mixture during a specified waiting period, and that the waiting period has elapsed, the The system again supplies an injection signal for setting a rich mixture to all injectors,
And the delivery control system is configured (13) so as,
A control device for individual cylinder fuel injection.   2. The delivery control system (13) characterized in that it is configured to set the waiting time (TW) as a function of a current value of a specified operating parameter of the internal combustion engine. The control device described.   The delivery control system (13) is characterized in that it is configured to perform a ramped transition from a rich mixture to a stoichiometric / lean mixture and vice versa. 2. The control device according to 2.

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