Electricity: measuring and testing – Internal-combustion engine ignition system or device – In situ testing of spark plug
Reexamination Certificate
1999-04-20
2001-06-19
Metjahic, Safet (Department: 2858)
Electricity: measuring and testing
Internal-combustion engine ignition system or device
In situ testing of spark plug
C324S399000, C324S402000
Reexamination Certificate
active
06249123
ABSTRACT:
TECHNICAL FIELD
The present invention relates to testing systems used during assembly of an article of manufacture, such as a vehicle engine, and more particularly to an automated apparatus and method for determining whether a size of a gap formed by two conductive nodes within a component of an article of manufacture is within an acceptable range during assembly of the article of manufacture.
BACKGROUND OF THE INVENTION
The present invention will be described for determining whether a size of a spark plug gap is within an acceptable range during manufacture of a vehicle engine. However, the present invention may be used for determining whether the size of a gap formed by two conductive nodes within any type of component assembled into any type of article of manufacture is within an acceptable range during assembly of the article of manufacture, as would be apparent to one of ordinary skill in the art from the description herein.
Referring to
FIG. 1
, a spark plug
102
is installed into a vehicle engine
104
.
FIG. 1
shows a cut-away view of a portion of the vehicle engine
104
having the spark plug
102
installed therein. A spark plug, which is a common component of a combustion engine, has a spark plug gap which electrically bridges for running the combustion engine, as known to one of ordinary skill in the art. Referring to
FIG. 1
, the spark plug
102
has a first conductive node
106
and a second conductive node
108
. The spark plug gap of the spark plug
102
is the space between the first conductive node
106
and the second conductive node
108
. The first conductive node
106
is conductively coupled to a top conductive node
107
.
In the modem assembly line for manufacture of vehicle engines, a spark plug is installed within a spark plug chamber
110
of the vehicle engine
104
with an automated robotic system. During the assembly of the vehicle engine
104
, the first conductive node
106
and the second conductive node
108
at the tip of the spark plug
102
may be accidentally smashed together. Thus, the size of the spark plug gap formed by the first conductive node
106
and the second conductive node
108
may then become undesirably smaller than an acceptable range. When the size of the spark plug gap is smaller than the acceptable range, the vehicle engine
104
may misfire and/or may run rough.
In a typical prior art assembly line for manufacture of vehicle engines, the vehicle engine
104
is not run until a relatively long time after the spark plug
102
has been installed into the vehicle engine
104
since many other components are also assembled into the vehicle engine
104
before the vehicle engine may be run. Thus, the size of the spark plug gap may not be readily checked at or near the location for installing the spark plug within the assembly line for manufacture of the vehicle engine
104
. However, corrective measures for dealing with a defective spark plug may be most efficiently performed at or near the location for installing spark plugs within the assembly line for manufacture of the vehicle engine
104
.
Thus, a system is desired for checking the size of the spark plug gap
102
that has been installed into a vehicle engine
104
at or near the location for installing spark plugs within the assembly line for manufacture of the vehicle engine
104
. Such a system effectively checks for the size of the spark plug gap during assembly of the vehicle engine, and thus does not require a running vehicle engine that is completely assembled.
In contrast, unfortunately, the prior art systems for checking or monitoring the spark plug gap, such as U.S. Pat. No. 3,904,955 to Katz and U.S. Pat. No. 5,491,416 to Klimstra et al. depend on the wiring of a running combustion engine that is completely assembled. Thus, these prior art systems may not be amenable for checking the size of the gap of a spark plug assembled into a vehicle engine at or near the location for installing the spark plug before the vehicle engine has been completely assembled.
U.S. Pat. No. 4,024,469 to Bobulski discloses an apparatus for measuring spark plug gap spacing by applying an AC voltage across the spark plug gap and then measuring the time from the zero-crossing of this AC voltage to the time point of the spark plug firing. However, such an apparatus of the prior art uses predominantly analog components such as numerous differential amplifiers. Thus, this prior art apparatus does not disclose the use of a microcontroller for a more flexible and reliable checking of the size of a spark plug gap during assembly of an article of manufacture.
SUMMARY OF THE INVENTION
Accordingly, the present invention is an assembly line testing apparatus and method for determining whether a size of a gap, within at least one component of an article of manufacture, is within an acceptable range, during assembly of the article of manufacture. Generally, the present invention includes a high voltage pulse circuit, disposed as part of the assembly line testing apparatus, for generating an increasing high voltage to be applied in series with the gap. The gap electrically bridges when the increasing high voltage reaches a firing voltage that depends on the size of the gap. In addition, the present invention includes a step down transformer having a primary winding that is coupled in series with the gap. The step down transformer has a secondary winding with a generated voltage thereon when the gap electrically bridges, and this generated voltage depends on the size of the gap. In the present invention, a microcontroller, operatively coupled to the secondary winding of the step down transformer, inputs a measured signal corresponding to the generated voltage on the secondary winding of the step down transformer to determine whether the size of the gap is within the acceptable range from the measured signal. The acceptable range is programmable within the microcontroller.
In addition, the microcontroller controls the high voltage pulse circuit to repeat a plurality of times a test cycle of applying the increasing high voltage in series with the gap and of determining whether the size of the gap is within the acceptable range from a respective measured signal generated for each of the test cycle. A display of the present invention is coupled to be controlled by the microcontroller to indicate that the size of the gap is within the acceptable range if the gap is determined to be within the acceptable range at least a predetermined number of times from a maximum number of times of repeating the test cycle. The predetermined number and the maximum number are programmable within the microcontroller of the present invention.
In this manner, the testing apparatus of the present invention includes substantially all of the components for checking the size of the gap, apart from the article of manufacture being tested. Thus, the size of the gap may be determined during assembly of the article of manufacture before the article of manufacture is completely assembled.
Furthermore, the microcontroller controls the operation of the assembly line testing apparatus of the present invention. The microcontroller of the present invention is programmed to automatically determine whether the gap size is within an acceptable range in a flexible and reliable manner. For example, the microcontroller has the flexibility of having a readily programmable acceptable range of the size of the gap. In addition, the microcontroller of the present invention checks that the size of the gap is within the acceptable range at least a predetermined number of times from a maximum number of times of repeating the determination of the gap size. Thus, the present invention results in a more reliable determination of whether the gap size is within the acceptable range. In addition, the present invention has the flexibility of having this predetermined number and the maximum number readily programmable into the microcontroller.
The present invention may be used to particular advantage for checking that the size of a spark plug gap within
Choi Monica H.
Honda of America Mfg. Inc.
Leroux E P
Metjahic Safet
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