Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
2000-04-03
2001-08-28
Hall, Carl E. (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S756000
Reexamination Certificate
active
06279223
ABSTRACT:
TECHNICAL FIELD
The present invention relates to manufacture of an object, such as a vehicle transmission system, that has a snap ring for holding a bearing, and more particularly to a method and apparatus for fabricating and testing a magnichanical sensor that detects for the presence of the snap ring during manufacture of such an object.
BACKGROUND OF THE INVENTION
The present invention will be described for ensuring the presence of a snap ring during manufacture of a vehicle transmission system. However, the present invention may be used for ensuring the presence of the snap ring during manufacture of any other object of article of manufacture, as would be apparent to one of ordinary skill in the art from the description herein.
Referring to
FIG. 1
, a bearing
102
is coupled to a part of a mission case
104
holding a vehicle transmission system. The bearing
102
fits within a mission case bearing hole
106
. The bearing
102
has a snap ring groove
108
. A snap ring fits within the snap ring groove
108
, and the snap ring holds the bearing
102
to the mission case
104
within the mission case bearing hole
106
.
During manufacture of the vehicle transmission system, the bearing
102
is initially placed around a spreader shaft
110
. A snap ring
112
is initially placed around a plurality of fingers, including a first finger
114
, a second finger
116
, a third finger
118
, and a fourth finger
120
.
During manufacture of the vehicle transmission system, the snap ring
112
and the plurality of fingers
114
,
116
,
118
, and
120
are disposed within the mission case bearing hole
106
. The spreader shaft
110
holding the bearing
102
is lowered toward the plurality of fingers
114
,
116
,
118
, and
120
. As the spreader shaft
110
makes contact with the plurality of fingers
114
,
116
,
118
, and
120
, the plurality of fingers are pushed outward such that the diameter of the snap ring
112
expands. Such an expansion of the snap ring
112
allows the snap ring
112
to fit around the bearing
102
as the bearing
102
is lowered into the mission case bearing hole
106
.
In addition, as the spreader shaft
110
makes contact with the plurality of fingers
114
,
116
,
118
, and
120
, the plurality of fingers are pushed downward. In this manner, when the snap ring
112
is aligned with the snap ring groove
108
on the bearing
102
, the fingers are moved away such that the snap ring
112
contracts back to a smaller diameter to fit snugly around the snap ring groove
108
on the bearing
102
. Also, at this point, the snap ring is holding in proper place the bearing
102
within the mission case bearing hole
106
of the vehicle transmission system.
During manufacture of the vehicle transmission system, the snap ring
112
may be mistakenly left out. A human operator may fail to place the snap ring
112
around the plurality of fingers
114
,
116
,
118
, and
120
by human error. Alternatively, an automated assembly machine may fail to place the snap ring
112
around the plurality of fingers
114
,
116
,
118
, and
120
because of machine malfunction.
However, a vehicle transmission system requires a snap ring to hold a bearing in place. Without a snap ring holding the bearing in place, the vehicle transmission system may fail to operate properly. However, because the snap ring is disposed inside the mission case
104
, the presence of the snap ring cannot be detected visually during further steps in the manufacturing process of the vehicle transmission system.
Accordingly, a magnichanical sensor is disposed on at least one of the plurality of fingers
114
,
116
,
118
, and
120
for monitoring the presence of the snap ring
112
during manufacture of the vehicle transmission system. Such a magnichanical sensor is described in a first copending patent application having Ser. No. 09/235,725 and filing date of Jan. 22, 1999, and having the common inventor and assignee herewith. Such a magnichanical sensor is also described in a second copending patent application having Ser. No. 09/235,890 and filing date of Jan. 22, 1999, and having the common inventor and assignee herewith. The first copending patent application having Ser. No. 09/235,725 and the second copending patent application having Ser. No. 09/235,890 are incorporated herewith by reference.
Referring to
FIG. 2A
, a first magnichanical sensor
202
is disposed within an opening
204
on a side of a finger
206
. Referring to
FIGS. 1 and 2A
, the finger
206
is one of the plurality of fingers
114
,
116
,
118
, and
120
. The opening
204
is disposed on the side of the finger that faces toward the snap ring
112
.
The magnichanical sensor
202
includes a magnetic field generator
208
and a magnetic switch
210
. The magnetic field generator
208
may be a rare earth magnet for example or any other source of magnetic field, as known to one of ordinary skill in the art. The magnetic switch
210
may be a reed switch or a hall effect switch for example or any other type of switch which opens and closes depending on the configuration of a magnetic field, as known to one of ordinary skill in the art. In addition, the magnichanical sensor further includes a snap ring presence indicator
212
that is coupled to the magnetic switch
210
.
Referring to
FIG. 2A
, a first position of the magnetic field generator
208
is aligned with a second position of the magnetic switch
210
such that the magnetic field (shown by dashed lines in
FIG. 2A
) generated by the magnetic field generator
208
maintains the magnetic switch
210
to be open. When the magnetic switch
210
is open, the snap ring presence indicator
212
determines that a snap ring is not present around the plurality of fingers
114
,
116
,
118
, and
120
.
Referring to
FIGS. 1 and 2B
, when the snap ring
112
is placed around the plurality of fingers
114
,
116
,
118
, and
120
, the snap ring
112
which is comprised of a ferrous material alters the magnetic field generated by the magnetic field generator
208
. Note that elements having the same reference number in
FIGS. 2A and 2B
refer to elements having similar structure and function. Such an alteration of the magnetic field (shown by dashed lines in
FIG. 2B
) causes the magnetic switch
210
to transition from being open to being closed. When the magnetic switch
210
is closed, the snap ring presence indicator
212
determines that the snap ring
112
is present around the plurality of fingers
114
,
116
,
118
, and
120
.
In this manner, the magnichanical sensor
202
detects for the presence of the snap ring
112
during manufacture of the vehicle transmission system. If the snap ring is determined to be not present as illustrated in
FIG. 2A
during placing of the bearing
102
into the mission case
104
, an alarm alerts an operator to this undesirable situation.
Alternatively, referring to
FIG. 3A
, the first position of the magnetic field generator
208
may be aligned with the second position of the magnetic switch
210
such that the magnetic field (shown by dashed lines in
FIG. 3A
) generated by the magnetic field generator
208
maintains the magnetic switch
210
to be closed. Note that elements having the same reference number in
FIGS. 2A and 3A
refer to elements having similar structure and function. When the magnetic switch
210
is thus closed, the snap ring presence indicator
212
determines that a snap ring is not present around the plurality of fingers
114
,
116
,
118
, and
120
.
Referring to
FIGS. 1 and 3B
, when the snap ring
112
is placed around the plurality of fingers
114
,
116
,
118
, and
120
, the snap ring
112
which is comprised of a ferrous material alters the magnetic field generated by the magnetic field generator
208
. Note that elements having the same reference number in
FIGS. 3A and 3B
refer to elements having similar structure and function. Such an alteration of the magnetic field (shown by dashed lines in
FIG. 3B
) causes the magnetic switch
210
to transition from being closed to being open. When the
Choi Monica H.
Hall Carl E.
Honda of America Mfg. Inc.
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