Internal combustion engine with two-stage combustion chamber

An improvement in an internal combustion engine of type in which a piston reciprocates in a cylinder to compress a charge of fuel within a combustion chamber within which the charge of fuel is ignited to burn and drive the piston through a power stroke, the improvement providing the combustion chamber with a first stage chamber and a second stage chamber communicating with one another through a valve operated in synchronism with reciprocation of the piston to close communication between the first stage chamber and the second stage chamber as the piston approaches top dead center so as to enable ignition and burning of a first portion of the charge of fuel in the first stage chamber, isolated from a second portion of the charge of fuel in the second stage chamber, and then to open communication between the first stage chamber and the second stage chamber to effect ignition of the second portion of the charge of fuel in the second stage chamber by the combustion products of the first portion of the charge of fuel and completion of the power stroke of the piston.

The present invention relates generally to internal combustion engines and 
pertains, more specifically, to an improvement in internal combustion 
engines of the type in which a piston reciprocates within a cylinder, 
driven by the combustion of a charge of fuel in a combustion chamber. 
The current demand for greater fuel economy and reduced pollution has led 
to the quest for internal combustion engines with increased fuel 
efficiency and decreased unwanted emissions. The present invention 
provides an improvement in internal combustion engines for achieving that 
result and exhibits several objects and advantages, some of which are 
summarized as follows: Enables more complete combustion of fuel for 
greater fuel efficiency and reduced emission of unwanted pollutants; 
provides a relatively simple modification which is adapted readily to 
existing internal combustion engine configurations, for widespread use in 
virtually all internal combustion engines of the type in which a piston 
reciprocates within a cylinder driven by the combustion of a charge of 
fuel in a combustion chamber; requires a minimum number of added parts for 
a maximum benefit; attains improved performance with minimal modification 
of current engine design; achieves added flexibility of operation, with 
increased power derived without a concomitant increase in fuel 
consumption; enables the modification of two-stroke as well as four-stroke 
engines for essentially universal application to current internal 
combustion reciprocating engine designs; is accomplished with component 
parts of simplified design and rugged construction for reliable 
performance over an extended service life. 
The above objects and advantages, as well as further objects and 
advantages, are attained by the present invention which may be described 
briefly as an improvement in an internal combustion engine of the type in 
which a piston reciprocates within a cylinder toward a top dead center 
position to compress a charge of fuel within a combustion chamber, within 
which combustion chamber the charge is ignited by ignition means so as to 
burn and drive the piston away from the top dead center position through a 
power stroke, the improvement comprising: a first stage chamber and a 
second stage chamber communicating with one another to establish the 
combustion chamber; and valve means for operation in synchronism with the 
reciprocation of the piston in the cylinder to close communication between 
the first stage chamber and the second stage chamber and isolate a first 
portion of the charge of fuel in the first stage chamber from a second 
portion of the charge of fuel in the second stage chamber when the piston 
reaches a predetermined position during movement of the piston toward the 
top dead center position; the ignition means including an igniter operated 
by the ignition means in synchronism with the reciprocation of the piston 
in the cylinder to ignite the first portion of the charge of fuel in the 
first stage chamber so as to burn the first portion of the charge of fuel 
when the first portion is isolated from the second portion; the valve 
means further operating to open communication between the first stage 
chamber and the second stage chamber subsequent to ignition of the first 
portion of the charge of fuel to effect ignition of the second portion of 
the charge by the first portion of the charge and completion of the power 
stroke of the piston. 
The invention will be understood more fully, while still further objects 
and advantages will become apparent, in the following detailed description 
of a preferred embodiment of the invention illustrated in the accompanying 
drawing, in which:

Referring now to the drawing, and especially to FIGS. 1 through 3 thereof, 
a working portion of an internal combustion engine 10 is seen to include a 
cylinder 12 within which a piston 14 reciprocates to rotate a crankshaft 
16, through a connecting rod 18, in a manner now conventional in 
reciprocating internal combustion engines. The cylinder 12 includes a 
cylinder head 20 through which an intake passage 22 and an exhaust passage 
24 communicate with the cylinder 12. An intake valve 26 and an exhaust 
valve 28 are operated in synchronism with the reciprocating movement of 
the piston 14 to admit a charge of fuel into the cylinder 12 so that the 
charge of fuel can be compressed and then burned to drive the piston 14 
through a power stroke, in a well-known manner. 
Thus, in FIG. 1, the piston 14 is shown in the bottom dead center position, 
a charge of fuel, such as a conventional mixture of air and a hydrocarbon, 
as illustrated at 30, has been admitted into the cylinder 12, and the 
intake valve 26 and the exhaust valve 28 are closed in preparation for an 
upward compression stroke of the piston 14 to compress the charge of fuel 
30 into a combustion chamber 32 juxtaposed with the cylinder head 20. In 
the improvement of the present invention, the combustion chamber 32 is 
constructed in a two-stage configuration and includes a first stage 
chamber 34 and a second stage chamber 36. The first stage chamber 34 is 
located in the cylinder head 20 and preferably has a frusto-conical 
configuration. As the piston 14 moves upwardly toward the top dead center 
position, the charge of fuel 30 is compressed, in both the first stage 
chamber 34 and the second stage chamber 36, since both the first stage 
chamber 34 and the second stage chamber 36 are in open communication with 
one another. 
When the piston 14 reaches the predetermined position illustrated in FIG. 
2, communication between the first stage chamber 34 and the second stage 
chamber 36 is closed by valve means illustrated in the form of a valve 
member 40 carried by the piston 14 so as to be seated in a complementary 
valve seat 42 in the cylinder head 20 in synchronism with the movement of 
piston 14. Valve member 40 is actuated by valve member actuating means 
shown in the form of a valve stem 44 integral with the valve member 40 and 
received within a bushing 45 secured within top 46 of the piston 14 to 
pass through the top 46 of the piston 14 and be affixed at 48 to resilient 
biasing means in the form of a leaf spring 50 coupled to the piston 14, 
beneath the top 46 of the piston 14, by projections 52 unitary with the 
piston 14 and projecting radially inwardly to support the ends 54 of the 
leaf spring 50. Upon such closing of communication between the first stage 
chamber 34 and the second stage chamber 36, the charge of fuel 30 is 
divided into a first portion 56 within the first stage chamber 34 and a 
second portion 58 within the second stage chamber 36 of the combustion 
chamber 32, which second stage chamber 36 is placed between the cylinder 
head 20 and the top 46 of the piston 14, the top 46 of the piston 14 being 
juxtaposed with the cylinder head 20. Ignition means, including an igniter 
in the form of a spark plug 60, operates in synchronism with the movement 
of the piston 14 to ignite the first portion 56 of the charge of fuel 30, 
as seen in FIG. 2, so as to burn the first portion 56 when the first 
portion 56 is isolated from the second portion 58 of the charge of fuel 
30. Continued upward movement of the piston 14, between the position 
illustrated in FIG. 2 and the position illustrated in FIG. 3, causes 
relative movement between the valve member 40 and the piston 14, enabled 
by downward flexing of the leaf spring 50. 
The burning of the first portion 56 of the charge of fuel 30 increases the 
pressure in the first stage chamber 34, until the increased pressure 
attains a predetermined pressure which overcomes the force biasing the 
valve member 40 into the valve seat 42 so as to open communication between 
the first stage chamber 34 and the second stage chamber 36, as seen in 
FIG. 3. Upon opening communication between the first stage chamber 34 and 
the second stage chamber 36, the high temperature, high pressure 
combustion products in the first stage chamber 34 ignite the second 
portion 58 of the charge of fuel 30, which second portion 58 is in the 
second stage chamber 36, to initiate combustion in the second stage 
chamber 36. The intensity of the high temperature, high pressure 
combustion products emanating from the first stage chamber 34 over the 
entire relatively large area of communication opened up by movement of the 
valve member 40 away from the valve seat 42 very quickly effects 
combustion of the second portion 58 of the charge of fuel 30 in the second 
stage chamber 36 for the efficient ignition and combustion of the second 
portion 58 of the charge of fuel 30 in the second stage chamber 36. It is 
noted that the relatively large area of communication opened up by 
movement of the valve member 40 away from the valve seat 42 is an annular 
area 61 so that ignition and combustion of the second portion 58 of the 
charge of fuel 30 takes place over a full 360.degree. extent for maximum 
effectiveness. As the piston 14 passes through the top dead center 
position, combustion is continued to drive the piston 14 downwardly, away 
from the top dead center position, through a power stroke. 
The two-stage combustion attained by the two-stage combustion chamber 
described above enables combustion to be initiated earlier during the 
travel of the piston 14 toward the top dead center position, thereby 
providing more time for combustion to take place and enabling more 
complete combustion for greater fuel efficiency and reduced pollutants. 
Thus, as seen in FIG. 4 in which the reciprocating movement of the piston 
14 and the rotation of the crankshaft 16 are shown diagrammatically at 62 
and 64, respectively, ignition of the charge of fuel 30 is initiated at 
the predetermined position of the piston 14 shown diagrammatically at 66, 
relative to top dead center 68, and corresponding position 70 of the 
crankshaft 16, well ahead of the position 72, and corresponding position 
74 of the crankshaft 16, where ignition is initiated in a conventional 
reciprocating internal combustion engine which does not incorporate the 
improvement of the present invention. The ability to advance ignition of 
the charge of fuel accommodates high speed operation of the engine 10 
while attaining more complete combustion of the charge of fuel for higher 
efficiency and better fuel economy, while reducing the emission of 
pollutants which otherwise would result from incomplete combustion. 
It will be seen that the improvement of the present invention attains the 
several objects and advantages summarized above, namely: Enables more 
complete combustion of fuel for greater fuel efficiency and reduced 
emission of unwanted pollutants; provides a relatively simple modification 
which is adapted readily to existing internal combustion engine 
configurations, for widespread use in virtually all internal combustion 
engines of the type in which a piston reciprocates within a cylinder 
driven by the combustion of a charge of fuel in a combustion chamber; 
requires a minimum number of added parts for a maximum benefit; attains 
improved performance with minimal modification of current engine design; 
achieves added flexibility of operation, with increased power derived 
without a concomitant increase in fuel consumption; enables the 
modification of two-stroke as well as four-stroke engines for essentially 
universal application to current internal combustion reciprocating engine 
designs; is accomplished with component parts of simplified design and 
rugged construction for reliable performance over an extended service 
life. 
It is to be understood that the above detailed description of a preferred 
embodiment of the invention is provided by way of example only. Various 
details of design and construction may be modified without departing from 
the true spirit and scope of the invention as set forth in the appended 
claims.