Spark plug load testing for an internal combustion engine

• US 4,291,383 A
• Filed: 12/20/1979
• Issued: 09/22/1981
• Est. Priority Date: 12/20/1979
• Status: Expired due to Term

• Current Assignee: Hamilton Test Systems Incorporated
• Original Assignee: United Technologies Corporation (Rtx Corporation)
• Inventors: Tedeschi, Rinaldo R., Full, Gary G.
• Primary Examiner(s): Gruber, Felix D.
• Application Number:
  US06/105,680
• Time in Patent Office: 642 Days
• Field of Search: 73/116, 73/117.2, 73/117.3, 364/551, 324/380-384
• US Class Current: 701/102
• CPC Class Codes: F02B 2075/027 four
• CPC Class Codes: F02P 17/00 Testing of ignition installations, e.g. in combination with adjusting testing fuel injection apparatus F02M65/00; testing ignition installations in general F23Q23/00; Testing of ignition timing in compression-ignition engines

Abstract

The spark voltage waveform at the secondary of the ignition coil of an internal combustion (IC) engine is sensed over a plurality of successive engine cycles. The instantaneous sub-cyclic position of the engine crankshaft is measured at successive crankshaft angle increments within each engine cycle and each sensed spark voltage signal is identified by the instantaneous value of crankshaft position at which it appears, thereby providing identification of each spark voltage signal with an associated cylinder of the engine. The number of samples for each cylinder together with the peak KV voltage magnitude and time duration of each are measured and the maximum, minimum and mean values of peak KV and spark duration for the spark signals associated with each cylinder together with the number of samples obtained are compared with the values obtained for each other cylinder to provide an indication of the relative sub-cyclic ignition efficiency of the ignition secondary circuit and the individual cylinders.

Claims

1. Apparatus for indicating the efficiency of the ignition system of an internal combustion (IC) engine connected at its crankshaft to the drive shaft of an engine load, the ignition circuitry providing secondary voltage signals as the spark plug voltage signal to each engine cylinder in each engine cycle, in the presence of associated ignition circuitry primary voltage signals, comprising:

first voltage sensing means for sensing the presence of each primary voltage signal and for providing a Lo-Coil voltage signal indicative thereof;

second voltage sensing means for sensing the actual magnitude of each secondary voltage signal and for providing a Hi-Coil voltage signal indicative thereof;

position sensing means, responsive to the interconnected engine crankshaft and load drive shaft, for providing engine crankshaft position signals indicative of the actual crankshaft angular position at successive crankshaft angle intervals in each engine cycle, said crankshaft angle intervals being less than that associated with a cylinder sub-cycle; and

signal processing means, responsive to said Lo-Coil voltage signals, said Hi-Coil voltage signals, and said crankshaft position signals, and having memory means for storing signals including specification signals defining the required crankshaft position of each cylinder spark plug voltage signal in each engine cycle in terms of actual crankshaft angle value,

for sampling, in response to each of said Lo-Coil voltage signals in a common engine cycle, and registering in said memory means, each of said Hi-Coil voltage signals and said crankshaft position signal appearing simultaneously therewith, and

for providing ratio signals of the actual magnitude of each of said Hi-Coil voltage signals sampled in a common engine cycle divided by the average value of all of said Hi-Coil voltage signals sampled in the same engine cycle, said ratio signals providing in combination an indication of the relative spark efficiency of the engine.

2. The apparatus of claim 1, further comprising:

crankshaft index sensor means, disposed on the engine for providing a crankshaft synchronization signal manifesting the occurrence of a selected engine cycle event; and

wherein

said signal processing means is further responsive to said crankshaft synchronization signal,

for providing, from said crankshaft synchronization signal and said specification signals in memory, cylinder position signals defining the actual crankshaft position of each cylinder spark plug voltage signal in terms of crankshaft angle interval values in each engine cycle, and

for comparing the sampled values of said crankshaft position signal with said cylinder position signals, to identify each Hi-Coil voltage signal sample as being associated with one of the engine cylinders, whereby said ratio signal indications of relative spark efficiency are provided in terms of identified engine cylinders.

3. The method of indicating the efficiency of the ignition system of an internal combustion engine operating with a crankshaft connected engine load, the ignition system providing spark plug voltage signals to each cylinder in each engine cycle, comprising the steps of:

sensing the actual position of the engine crankshaft at successive crankshaft angle intervals in each engine cycle and providing crankshaft position signals indicative thereof, each crankshaft angle interval being less than that associated with a cylinder sub-cycle;

measuring together the actual magnitude of each spark plug voltage signal and the values of all of said crankshaft position signals appearing simultaneously therewith to provide, in each engine cycle, signals indicative of the actual magnitude of each spark plug voltage signal and signals indicative of the range of actual crankshaft angles associated with each;

ascribing each of said ranges of measured crankshaft angle values to a different cylinder spark ignition event in a common engine cycle; and

comparing the actual magnitudes of the spark plug voltage signals ascribed to each cylinder ignition in a common engine cycle with the actual magnitudes of the spark plug voltage signals ascribed to all other cylinders in the same engine cycle, to provide the indication of ignition system efficiency.

4. The method of claim 3, wherein said step of comparing includes:

calculating the average magnitude of the spark plug voltage signals measured in a common engine cycle; and

providing for each cylinder a signal ratio of the actual magnitude of the spark plug voltage signal ascribed to such cylinder'"'"'s spark ignition event divided by said average magnitude of all spark plug voltage signals measured in said common engine cycle, whereby said ratio signals provide a relative indication of the ignition system efficiency.

5. The method of claim 4, further comprising the steps of:

determining the range of crankshaft angle values specified by the engine manufacturer as defining the required location of each cylinder'"'"'s spark ignition in each engine cycle; and

identifying each of said measured ranges of actual crankshaft angle values as associated with a particular one of said manufacturer specified ranges, so as to relate each of said measured spark plug voltage signals with an identified engine cylinder, whereby said ratio signal indications are each identified as associated with a particular engine cylinder.