Internal-combustion engines – Charge forming device – Including exhaust gas condition responsive means
Patent
1991-04-15
1992-09-29
Argenbright, Tony M.
Internal-combustion engines
Charge forming device
Including exhaust gas condition responsive means
123479, F02D 4172, F02D 4134, F02D 4178
Patent
active
051506980
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a method and an arrangement for adjusting the amount of fuel to be supplied even in an emergency operation to an internal combustion engine, which has a lambda controller and an idling contact. The emergency operation concerns a situation, in which the load signal used in normal mode for determining the amount of fuel, fails.
BACKGROUND OF THE INVENTION
If, in conventional fuel amount setting arrangements for internal combustion engines, the load signal fails, this is detected by a means which tests the presence of this signal and in response, the means switches over from normal mode to emergency operation mode. In the emergency operation mode, a plurality of permanently predetermined emergency injection times are used in dependence upon certain operating states. Since the necessary fuel requirement, however, depends to a large degree on the load, the same amount of fuel at, for example, a certain engine speed leads to widely varying lambda values in dependence upon the operating conditions present in each case. The error in the fuel metering can be so large that the intake air/fuel mixture can no longer be ignited. Thus, a large degree of environmental damage may arise due to fuel which has not been combusted at all or only incompletely combusted. In addition, the catalytic converter present in lambda-controlled systems is damaged if it has reached its working temperature and a non-combusted mixture reaches it.
Japanese patent publication 59 028 030 describes a process which permits the emergency operation of an internal combustion engine in the event of the failure of the air-flow sensor. Within the scope of this process, only a basic injection time is used for metering the amount of fuel. This basic injection time is essentially multiplied by the reciprocal value of the engine speed and, in addition, contains signals of an idling switch and of an air/fuel ratio sensor.
A process for lambda control, which, even in normal operation, has no special sensor for detecting a load signal is disclosed in German patent publication DE-OS 3,714,245. In the process described, the detection of a load signal (air-flow measuring component) is dispensed with in order to reduce the complexity of the control arrangement. The fuel metering signal is formed as a function of the difference of a lambda actual value and of a lambda desired value. The lambda desired value is taken from a memory from a stored characteristic field as a function of the engine speed and an air-flow value. The air-flow value is, in turn, computed from the lambda actual value and the fed-back fuel metering signal.
SUMMARY OF THE INVENTION
The invention is based on the object to provide a method for emergency operation lambda control which permits even in emergency operation to always provide an ignitible mixture.
Furthermore, the invention is based on the object of specifying an arrangement for carrying out such a method.
The method of the invention is for setting the amount of fuel to be metered to an internal combustion engine having a lambda controller and an idling contact during normal operation as well as during emergency operation wherein the load signal, which coacts during normal operation for determining the amount of fuel, is not available, and for the condition of non-idle operation and with the lambda probe in operational readiness.
A first embodiment of the method of the invention includes the steps of: predetermining at least one emergency injection time; forming an output variable of a lambda controller for the difference between the lambda actual value and a lambda desired value; modifying each injection time with the output variable of the lambda controller thereby forming an injection time duration having a width dependent upon the selected maximum amplitude of said output variable; selecting the number of injection time durations and the maximum amplitude of said output variable so as to cause the injection time durations to cover all injection times which can occur during ope
REFERENCES:
patent: 3952710 (1976-04-01), Kawarada et al.
Patent Abstracts of Japan, vol. 8, No. 124 (M-301), Jun. 1984.
Patent Abstracts of Japan, vol. 11, No. 10 (M-552), Jan. 1987.
Franzke Klaus
Kohler Rolf
Kratt Alfred
Argenbright Tony M.
Ottesen Walter
Robert & Bosch GmbH
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