Note: Descriptions are shown in the official language in which they were submitted.
3~
The present invention relates to gaging in-
strumentation and, more specifically, to an instrument
for gaging the side Eace taper angle of high perform-
ance piston rings.
High performance reciprocating piston inter-
nal combustion engines often include piston compression
and/or oil control rings having frustoconical axial or
side ring faces which are adapted to mate in sealing
engagement with corresponding opposed faces of a seal
groove in the piston. When viewed in radial cross sec-
tion, the side faces of such rings taper toward each
other in the direction of the ring axis. Hence, piston
rings of the described type are often referenced in the
art, and are referenced hereinafter, as tapered piston
rings. For optimum engine performance, the angle of
taper of each ring side face, and the included angle of
taper measured between the two ring side faces, must be
closely matched to the corresponding taper angles of the
piston groove in which the ring is to be seated.
I-t is an object of the presen-t invention to
provide a gage for measuring the side face taper angle
and/or the included taper angle between the side faces
of a piston ring of the above-described type which is
economical in manufacture and assembly, which is accu-
rate and reliable in operation, which has a minimum
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number of moving parts, which may be readily calibrated
and/or which yields a direct reading in minutes of de-
parture of the measured taper angle from a preselected
nominal value.
The novel features which are considered to be
characteristic of the present invention are set forth
in particular in the appended claims. The invention
itself, however, together with additional objects, fea-
tures and advantages thereof, will be best understood
from the following description when read in conjunction
with the accompanying drawings in which:
FIG. 1 iS a side elevational view of an em-
bodiment of the invention which is adapted for gaging
the side face angle of a tapered piston ring;
FIG. 2 is a side elevational view of an alter-
native embodiment of the invention shown in FIG. 1; and
FIG. 3 is a side elevational view of an em-
bodiment of the invention which is adapted for gaging
the included angle between the side faces of a tapered
2 0 piston ring.
One embodiment 10 of the piston ring side
taper gage provided by the invention is shown in FIG.
1 and comprises a gaging plate 12 having a horizontal
plane reference surface 14. A bracket 20 is carried
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by plate 12 and has a measuring anvil 22 mounted thereto
by a pivot pin 24 such that anvil 22 is free to rotate
in a plane perpendicular to reference surface 14 about
a f i~ed pin axis . The lower or gaging surface 26 of
anvil 22 is accurately machined to have either a flat
or frustoconical surface contour with an angle of taper
preferably equal to a preselected nominal taper angle
of a piston ring side face. A dial indicator 30 is
carried vertically by bracket 20 and has a measuring
spindle 32 depending therefrom to contact a flat upper
surface 34 of anvil 22. Thus, the position of the con-
tact point between spindle 32 and anvil surface 34,
and, hence, the reading on dial indicator 30, is a
direct function of the angular position of anvil 22
about its pivot axis.
For the purpose of explaining the operation
of gage 10, a tapered piston ring 36 is shown in FIG.
1 and has frustoconical side faces 38,40. The taper
angle of side face 38 is to be measured. Ring 36 is
positioned generally coaxially about indlcator 30 and
bracket 20 and res-ts on reference surface 14 on a ring
side edge 42. The ring is then slid along surface 14
until the side face 38 remote from edge 42 is in inti-
mate contact with anvil gaging surface 26 at a point
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in the ring circumference where the measurement is to
be taken. Anvil 22 will assume a position about its
pivot a~is as a function of the angle between side
face 38 and reference surface 14, and will thus provide
a measurement of such angle on the face of dial indica-
tor 30. It will be evident that the angle of taper of
ring side face 40 may be readily measured by merely re-
moving the ring from gage 10, inverting the ring, and
then replacing the ring on the gage with face 40 in
the upper position in intimate contact with gaging sur-
face 26.
It is a significant feature of the present
invention that, by selecting an appropriate distance
d between the axis of pin 24 and the axis of spindle
32, measured in a direction perpendicular to both axes
as seen in FIG. 1, dial indicator 30 may be made tc
yield readings direc-tly in minutes of side face taper
angle~ More specifically, the distance d is preferably
calculated to satisfy the equation:
d = a/tan ~0, (1)
wherein a is a preselected unit of linear spindle dis-
placement and a~ is the change or departure from nom-
inal of the side face taper angle selected to correspond
to such unit of spindle displacementO For small values
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of a~ expressed in radians:
e = tan ~. (2)
Hence, if indicator 30 is graduated in increments of ten
thousandths of an inch (O.OQOlinch), each indicator
graduation will correspond to one minute of taper angle
when distance d is made equal to 0.343775 inch. Where
upper anvil surface 34 is perpendicular to the axis of
spindle 32 in the nominal anvil position, as is preEer-
red, the inherent error of the present invention as
described is less than seven parts per million (7 x 10
percent) over an angular range (~ ~) of thirty minutes,
iOe., the nominal side face taper angle plus or mlnus
f ifteen minutes. Furthermore, gage 10 may be readily
calibrated to the preselected nominal side face taper
angle by merely replacing ring 36 in FIG. 1 with a
second anvil identical to anvil 22, and then zeroing
indicator 300 Moreover, gage 10 may be readily adapted
for any one of a number of nominal side face taper angles
by merely replacing anvil 22 with another anvil having
the desired nominally machined gaging surfaceO
A modified embodiment 50 of the i~vention,
again for measuring the angle of taper of one ring side
face, is shown in FIG. 2, wherein reference numerals
identical to those used in FIG. 1 indicate identical
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parts. In the embodiment of FIG. 2, indicator 30 is
horizontally mounted by a bracket 52 with spindle 32
extending therefrom to engage a flat vertical surface
54 on a measuring anvil 56.~ It will be evident that
anvil 56 is similar to anvil 22 of FIG~ 1~ with the
exception of the vertical projection extending from
the main body of anvil 56 to provide spindle engaging
surface 54. The distance d discussed in detail in con-
nection with FIG~ 1 is again measured in FIG~ 2 between
the spindle and pivot pin axes in a direction perpen-
dicular to both, this time in the vertical direction.
The embodiment of FIG~ 2 has the advantage that the
face of the dial indicator may be viewed from above.
However, there is a slight disadvantage in the embodi
lS ment of FIGn 2 in that the gage cannot be calibrated
merely by using a second anvil identical to anvil 56.
A gaging anvil of separate design, similar to anvil 22
in FIG~ 1 for example, must be used.
Another modified embodiment 60 of the inven-
tion is shown in FIG~ 3, and is adapted for measuring
the included angle of taper between ring side ~aces
38,40. In the embodiment of FIG~ 3, a frustoconical
reference surface 62 is provided by a suitably machined
block 64 mounted by a bracket 66 to a stationary ver-
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tical support 6~3. The cone angle of surface 62, i.e.,the angle of surface 62 with respect to the vertical,
is preferably equal to the nominal angle of one ring
side face. An anvil 70 having a gaging surface 72 is
pivotably carried on bracket 66 by a pin 74O Dial in-
dicator 30 is also carried by bracket 66 with indicator
spindle 32 extending horizontally into engagement with
a flat rear anvil surface 76. As in the embodiments
of FIGS. 1 and 2, gaging surface 72 in the embodiment
of FIG. 3 is machined at an angle with respect to the
vertical equal to the nominal taper of one ring side
face, rear anvil surface 76 is perpendicular to the
axis of spindle 32 in the nominal position of gaging
surface 72 with respect to reference surface 62, and
distance d is measured between the pin and spindle axes
in a direction perpendicular to both.
In the operation of the embodiment of FIG. 3,
a piston ring 36 is to be placed between reference sur-
face 62 and gaging surface 72 such that each of those
surfaces is in intimate contact with one of the piston
ring side faces 38,40. As in FIGSo 1 and 2, anvil sur-
faces 72,76 of FIGo 3 assume a position with respect
to reference surface 62 as a function of the ring 36
under test. The indicator dial in FIG. 3 provides a
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reading of the departure of the included angle between
gaging surface 72 and reference surface 62, i.e., be-
tween ring side faces 38,40, from the calibrated nom-
inal. The ring will be held in position by gravity
while the dial reading is recorded.
Although the piston ring side taper gage pro-
vided by the present invention has been described in
connection with three specific embodiments thereof, any
and all of which satisfy the several objects, aims and
advantages recited above, many modifications will sug-
gest themselves to skilled artisans. For example, it
will be apparent that any of the disclosed embodiments r
may be readily modified to orient the face of indicator
30 to be viewed from any desired direction by merely
modifying the associated anvil. For best accuracy, the
only practical constraint on such modifications is that
the axis of the indicator spindle should preferably be
perpendicular to the opposing anvil surface in the nom-
inal anvil position. It will also be apparent that all
three of the disclosed embodiments may be modified for
use with metric dial indicators by merely changing dis-
tance d in correspondence with the graduated displace-
ments displayed on the indicator dial. Moreover, where
greater or lesser angle measuring accuracy is desired,
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the distance d may be appropriately increased or de-
creased. Accordingly, the invention is intended to
embrace these and all other alternatives, modifications
and variations as fall with1n the spirit and broad
5 scope of the appended claims.
The invention claimed is:
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