Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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The present application is related to Canadian Appli-
cation Serial No. 259,548, filed August 20, 1976.
The present invention relates to variable compression
ratio (VCR) piston assemblies such as those disclosed in U. S.
Patent Nos. 3,156,162 3,161,112; 3,185,137; 3,185,138;
3,303,831; 3,311,096; 3,402,662; 3,418,982; 3,450,111;
3,417,738; 3,417,739; 3,450,112; 3,527,265; 3,405,698;
3~405/697~ 3,405,113; 3,407,791; 3,667,433 and 3,704,695;
all owned by Applicants' assignee, and more particularly to an
improved construction for such piston assemblies.
In the construction disclosed in the patents indicated
above, an inner piston member is connected in the usual
manner to a connecting rod and an outer piston member is
carried by and is axially movable relative to the inner mem-
ber. Relative movement of these members varies the compression
ratio of the particular cylinder in which the piston moves.
Clearance spaces are provided between the top and bottom ends
of the inner and outer members and these form upper and lower
chambers which vary conversely in volume in relation to the
relative movement of the members. An incompressible fluid
such as lubrication oil is supplied to these chambers in a
manner which automatically regulates movement of the members
to gradually change the compression ratioluntil a predetermined
combustion pressure has been achieved. The hydraulic system
then varies the movement of the members in a manner which tends
to maintain a uniform maximum combustion chamber pressure.
Copending Application Serial No. 259,548 discloses
an improvement upon the assemblies disclosed and claimed in the
aforementioned patents by providing a lightweight, inexpensive
VCR piston constructed to minimize the effects of inertia on the
discharge valve and to provide rapid response to variations in
engine load.
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The present invention provides a uni~ue valve for
regulating flow between the upper chamber and the lower chamber
of the assembly. Although it will be described as a part of
the assembly shown in copending application Serial No~ 259,548,
it should be understood that it has utility in other assemblies
including those illustrated in t~e aforementioned patents.
In the present invention, the lower oil chamber is
connected to the upper chamber through a passage which extends
through a groove provided for a sealing ring. The ring carried
in the ring groove, in addition to performing its usual function,
also acts as a check valve regulating the flow of oil from the
upper chamber to the lower chamber in a manner which gradually
increases the compression ratio of the engine until a pre-
determined maximum combustion chamber pressure has been achieved.
The invention is in an internal combustion engine, a
piston having an inner member and an outer member telescopically
received by said inner member, said members being movable in
response to reciprocation of the piston with respect to a combus-
tion chamber of the engine, a first fluid chamber and a second
fluid chamber varying in volume in response to said relative
movement and to variations in the quantity of fluid therein,
means supplying fluid to said chamber, said means comprising
a first passage in said piston connecting with said first fluid
chamber, a one way inlet valve disposed in said first passage,
and a second passage in said piston connecting said first chamber
with said second chamber, the improvement comprising a sealing
groove in said inner member and a sealing member carried in said
sealing groove, said second passage extending through said seal-
ing groove, and said sealing ring acting as a valve means to regu-
late fluid flow between said first and second chamber.
A better understand,ing of the present invention will
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be achieved upon reference to the following description which
~efers to the accompanying drawings in which like reference
numerals refer to ~ike parts throughout the several views and
in which:
FIG. 1 is a longitudinal cross-sectional view of a
piston assembly embodying a preferred construction of the
present invention and illustrating the assembly in one operational
position;
FIG. 2 is a view similar to FIG. 1 but illustrating
the assembly in another operational position;
FIG. 3 is a cross-sectional view as seen substantially
from line 3-3 of FIG. l;
FIG. 4 is a cross-sectional view as seen substantially
from line 4-4 of FIG. 2; and
FIG. 5 is an enlarged view of a portion~.of the
assembly shown in FIGS. 1 and 2.
Now referring to the drawings for a more detailed
description of the present invention, a preferred variable
compression ratio (VCR) piston 10 is illustrated as comprising
an inner member 12 having a radially reduced upper section 14.
An outer member 16 is mounted to the outer surface of the
reduced section 14.
The outer member 16 has a crown 18 which serves as
the head of the piston 10 and which forms a movable wall of
the lower boundry of the combustion chamber of the engine.
me outer member 16 is axially slidably mounted to the outer
surface of the section 14 of the inner member 12.
A plate 22 is mounted to the top of the inner member
12 preferably by bolts 23 (FIG. 3) and a ring 24 having external
threads 26 is mounted to the outer member 16 by threads 28
formed on the inside surface of the lower portion of the outer
member 16, the threaded engagement of ring 24 and member 16
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being only one preferrecl method o~ attachment. A lock means,
such as a lock pin 30 holds the ring 24 in position. P. sealing
ring 32 is carried by the plate 22 and a sealing ring 34 is
carried by the reduced section 14 of the inner member 12 and
engages the ring 24 to provide a fluid seal between the members
in the area of their sliding contact.
An upper chamber 36 is formed hetween the plate 22 and
the inside surface of the crown 18 and a lower annular chamber
33 is formed between the lower edge of the plate 22, the outer
member 16 and the ring 24 closely adjacent the ring groove area
37 of the piston 10.
As can best be seen in FIG. 5, a passage 4n is formed
in the plate 22 and connects the upper chamber 36 to a groove 33
which receives the sealing ring 32. A passage 41 is offset
slightly from the passage 40 and connects the groove 33 to the
lower chamber 38. The sealing ring 32 is carried in the groove
33 and is movakle under the influence of inertia, in a manner
which will become more anparent as the description proceeds, from
the position shown in FIG. 5 wherein fluid flow is open between
the passages 40 and 41 and a position in which the ring 32
rests against the upper surface of the groove 33 to block oil
flow through the passage 40.
Referring again to FIGS. 1 and 2, the inner member
12 is connected to a connecting rod 42 by a piston pin 44 in the
conventional manner of connecting engine pistons to a connecting
rod. An oil collector assembly generally indicated at 46 is
carried in a portion 48 of the inner member 12 extending down-
wardly into engagement with the top of the connecting rod 42.
The collector assembly 46 preferably comprises an internally
cored member 50 slidably carried in a recess 52 formed in the
inner piston 12 and having a lower edge formed to conform to the
upper surface of the connecting rod 42 so that as the connecting
rod 42 pivots on the pin 44, and with respect to the inner member
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12, the lower surface of the cap member 50 can conform tightly to
the upper surface of the connecting rod 42. A spring 54 carried
in the recess 52 urges the cap memb-er 50 outwardly into engage-
ment with the connecting rod 42.
The cap member 50 is provided with a central open-
ing 56 which registers with an outlet passage 58 formed in
the connecting rod 42. The passage 58 is connected with the
lubrication system of the engine by means not shown.
A valve assembly 60 is carried in a chamber 62 formed
in the plate 22 and includes a central substantially tubular
portion 64 having a lower end extending through the upper
portion of the inner member 12 to register with the recess 52.
An upper end extends through the plate 22 and has a passage 66
opening to the upper chamber 36. A ball 68 is carried within
the tubular portion 64 and is normally positioned on a seat 70
to block fluid flow through the tubular portion 64 to the passage
66 but is movable under pressure and inertia to a position open-
ing such fluid flow.
A radially extending central portion 72 of the valve
assembly 60 provides the means for carrying a tapered washer or
Belleville spring type discharge valve 74 which in its closed
position blocks flow from a passage 76 connected through the plate
22 to the upper chamber 36, to a passage 78 connected through
the inner member 12 to the crankcase ~not shown) of the engine.
As the invention has thus far been described it is
apparent that the inner member 12, being connected to the
connecting rod 42 in the conventional manner, moves up and down
within the cylinder of an internal combustion engine within
fixed limits and in the manner of a conventional piston.
The outer member 16 raciprocates within the cylinder within the
axial limits defined at its lower limit by the crown 18 en-
gaging the top of the plate 22 and at its upper limit by the
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top of the ring 24 engaging the lower edge of the plate 22.
Thus as the piston 10 reciprocates, the outer member 16 will
tend to move under the influence of inertia toward the extreme
uppermost and the extreme lowermost positions. The lubricant
Supplied to the chambers 36 and 38, however, regulates this
movement in a manner to provide.an increased compression ratio
for the engine while at the same time maintaining a predetermined
maximum combustion chamber pressure which is established by the
opening pressure setting of valve 74.
This is accomplished by the inertia and oil pressure
acting on the outer member 16 at the upper end of the exhaust
stroke and the early part of the downward intake stroke causing
the outer member 16 to separate from the inner member 12. As the
members separate, the upper chamber 36 expands and the ball 68,
which acts as a one way inlet valve, moves to a position to per-
mit oil to be directed to the expanding chamber 36 from the
passage 66. The ball 68 prevents the oil from passing back into
the supply valve assembly 60 from the upper chamber 36 on the
downward stroke of the piston.
Likewise, as the piston moves downwardly, the sealing
ring 32 will move to the position shown in FIG. 5 permitting oil
to flow from the upper chamber 36 to the lower chamber 38.
Reverse flow is prevented, however, during the upward stroke of
the piston as inertia will cause the sealing ring 32 to move to
a position closing fluid flow through the passage 40.
The result is that the piston assembly 10 will gradu-
ally be extended until a predetermined combustion chamber pres-
sure has been achieved. This will, of course, result from the
volume of the combustion chamber decreasing as the length of the
piston assembly 10 is increased.. When the combustion chamber
pressure has reached the predetermined value, the pressure in
the combustion chamber will be transmitted to the fluid in the
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upper chamber 36 to open the Yalve 23 and dump the oil in the
chamber 36 to the crankcase.
There is sufficient leakage past the sealing rin~ 3Z
to permit the oil to escape from the lower chamber 38. A re-
Stricted orifice (not shown) could if preferred be provided to
permit controlled leakage from the lower chamber 38.
The sealing ring 32 then provides an inexpensive
check valve for regulating the flow of oil from the upper chamber
36 to the lower chamher 38.
While it has been preferred to illustrate the valve
of the present invention in use in the assembly of our
aforementioned patent application, it should be apparent that
it can be used with other constructions and assemblies as well
including those disclosed in the aforementioned patents.
It is also apparent that although we have described
but one embodiment of our invention, many changes and modifica-
tions can be made therein without departing from the spirit of
the invention as expressed by the scope of the appended claims.
We claim:
