Measuring and testing – Engine detonation – Combustion signal compared to reference signal varied by a...
Patent
1982-09-29
1985-01-08
Goldberg, Gerald
Measuring and testing
Engine detonation
Combustion signal compared to reference signal varied by a...
73116, G01L 2322
Patent
active
044921080
DESCRIPTION:
BRIEF SUMMARY
STATE OF THE ART
The invention is based on a sensor apparatus of the species of the patent claim.
Combustion engines having internal combustion are only apparently continuous-operation engines. Although torque and rpm are quasi-continuous output variables, still they are generated by a rapid sequence of individual processes.
In the course of optimizing the operation of internal combustion engines and in particular with a view to reducing fuel consumption, it is therefore necessary to detect these interrelationships individually, in order to be able to influence the overall process in a desired manner by exerting influence on the individual processes.
The precondition for doing so is the detection of the status of the interior of the internal combustion engine. Typical status variables here are pressure and temperature, which in the case of the ideal gas indicate the overall status. Although the operation of engines with internal combustion is also determined to a great extent by chemical processes and changes in substances, so that such operation cannot be entirely encompassed by describing the pressure and temperature, still the observation of pressure and temperature provides sufficient information as to the changes in the status variables over the course of the engine cycle.
In this respect, it is known to perform the following operations in the combustion chamber of an internal combustion engine: the detection of the propagation of the combustion process over time and in spatial terms; the detection of the instant of ignition; the detection of injection processes; and the measurement of irregular combustions.
Among these irregular combustions is the phenomenon known as "knocking", which occurs in internal combustion engines under certain conditions. This term is understood to mean oscillations of audio frequency in the compressed fuel-air mixture, which are caused by a shock wave. During these oscillations, the transmission of heat to the piston and cylinder walls of the engine is increased greatly. The result is a harmful thermal overload of these surfaces, so that knocking must in principle be avoided. On the other hand, an effort is also made to exploit the available operating range of the engine to the fullest possible extent, so that means must be provided for indicating knocking early and reliably; in this manner, it is possible to realize a means of engine regulation in which the engine is always operated just below the knocking limit.
Besides the problem of furnishing sensors suitable for detecting knocking, the problem also exists in measurement technology of reading out the knocking signal, reliably and without interference, from the oscillations of the engine detected by the sensor, so that it is possible to regulate the engine appropriately in accordance with a knocking recognition signal of "knocking--YES" or "knocking--NO".
A method and an apparatus for ascertaining knocking in internal combustion engines is known from German Disclosure Document DE-OS No. 29 16 591. In the method described therein, the signal generated by a knocking sensor is integrated within a so-called measuring window, that is, within a predetermined crankshaft angle range or a predetermined time interval, and the signal integral thus obtained is compared with an average value of a multiplicity of signal integrals from preceding combustion cycles.
The known method has the disadvantage, however, that the reference value must be formed from a multiplicity of signal integrals, which requires a certain amount of time for measurement; the known method thus generally suffers from a certain inertia. On the other hand, however, it can also happen that in forming the average value of a multiplicity of signal integrals, signal integrals may be detected from both knocking combustions and non-knocking combustions together, so that an unequivocal signal for either knocking combustion or non-knocking combustion is no longer available as the reference signal, and only a mixed signal is available instead.
ADVANTAGES OF THE INVENTI
REFERENCES:
patent: 4153020 (1979-05-01), King et al.
patent: 4271469 (1981-06-01), Kawai et al.
patent: 4320729 (1982-05-01), Sawada et al.
patent: 4331117 (1982-05-01), Ginsburgh
patent: 4355534 (1982-10-01), Roger
Goldberg Gerald
Harding, Jr. Ellwood G.
Robert & Bosch GmbH
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