Free piston internal combustion engine

An improved internal combustion engine is disclosed having no rotating crank shaft. Each piston rod of the engine is connected to a hydraulic piston and cylinder the output of which drives the rotating output shaft of a hydraulic motor. A take off from the shaft of the hydraulic motor drives an air compressor which feeds compressed air to the combustion chamber through the latter's intake valve. Fuel is mixed with the compressed air before entering the combustion chamber and a conventional spark plug and coil is employed to ignite the fuel/compressed air mixture. The compressed air also is used to actuate the intake and exhaust valves of each cylinder through a solenoid controller. A computer is adapted to send signals to each valve solenoid to control its movement and to each spark plug coil in response to a throttle input and a piston displacement input applied to the computer. The input signal sensing piston displacement in each cylinder is derived from a linear potentiometer coupled between the piston rod and the hydraulic cylinder. The computer also operates a master hydraulic valve between the hydraulic cylinders and the hydraulic motor to control the direction of rotation of the hydraulic motor output shaft. Water injection means are provided for cooling each combustion chamber thereby dispensing with a conventional radiator cooling system.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates generally to internal combustion engines, and 
more particularly, to a new and improved internal combustion engine having 
no rotating crank shaft and no radiator cooling system thereby operating 
with greatly enhanced efficiency. 
2. Description of the Prior Art 
In conventional internal combustion engines of either the two-stroke or 
four-stroke type, efficiency is limited due to losses to friction and to 
heat lost through the radiator or cooling system. The need to maintain a 
conventional engine operative when it is not doing any useful work, i.e. 
when the engine is running and the crank shaft is turning during idling, 
for example, wastes fuel, reduces efficiency, and creates wear and tear on 
the engine parts. Similarly, the need of a conventional internal 
combustion engine to be cooled constantly by causing a stream of cooling 
fluid to flow through or over the walls of the engine expends 
approximately a third of the useful output of the engine. Clearly a need 
exist for a more efficient design of an internal combustion engine which 
does not require a constantly rotating crank shaft especially when the 
engine is in "idle," and which does not need to be constantly cooled by an 
efficiency robbing radiator or cooling system. Such need is met by the 
present invention as will be made apparent from the following description 
thereof. Other advantages of the present invention over the prior art also 
will be made self evident. 
SUMMARY OF THE INVENTION 
To achieve the foregoing and other advantages, the present invention, 
briefly described, provides an improved internal combustion engine having 
no rotating crank shaft. Each piston rod of the engine is connected to a 
hydraulic piston and cylinder the output of which drives the rotating 
output shaft of a hydraulic motor. A take off from the shaft of the 
hydraulic motor drives an air compressor which feeds compressed air to the 
combustion chamber through the latter's intake valve. Fuel is mixed with 
the compressed air before entering the combustion chamber and a 
conventional spark plug and coil is employed to ignite the fuel/compressed 
air mixture. The compressed air also is used to actuate the intake and 
exhaust valves of each cylinder through a solenoid controller. A computer 
is adapted to send signals to each valve solenoid to control its movement 
and to each spark plug coil in response to a throttle input and a piston 
displacement input applied to the computer. The input signal sensing 
piston displacement in each cylinder is derived from a linear 
potentiometer coupled between the piston rod and the hydraulic cylinder. 
The computer also operates a master hydraulic valve between the hydraulic 
cylinders and the hydraulic motor to control the direction of rotation of 
the hydraulic motor output shaft. Water injection means are provided for 
cooling each combustion chamber thereby dispensing with a conventional 
radiator cooling system. 
The above brief description sets forth rather broadly the more important 
features of the present invention in order that the detailed description 
thereof that follows may be better understood, and in order that the 
present contributions to the art may be better appreciated. There are, of 
course, additional features of the invention that will be described 
hereinafter and which will form the subject matter of the claims appended 
hereto. 
In this respect, before explaining the preferred embodiments of the 
invention in detail, it is to be understood that the invention is not 
limited in its application to the details of the construction and to the 
arrangements of the components set forth in the following description or 
illustrated in the drawings. The invention is capable of other embodiments 
and of being practiced and carried out in various ways. Also, it is to be 
understood, that the phraseology and terminology employed herein are for 
the purpose of description and should not be regarded as limiting. 
As such, those skilled in the art will appreciate that the conception, upon 
which this disclosure is based, may readily be utilized as a basis for 
desisting other structures, methods, and systems for carrying out the 
several purposes of the present invention. It is important, therefore, 
that the claims be regarded as including such equivalent constructions 
insofar as they do not depart from the spirit and scope of the present 
invention. 
Further, the purpose of the foregoing Abstract is to enable the U.S. Patent 
and Trademark Office and the public generally, and especially the 
scientists, engineers and practitioners in the art who are not familiar 
with patent or legal terms of phraseology, to determine quickly from a 
cursory inspection the nature and essence of the technical disclosure of 
the application. Accordingly, the Abstract is neither intended to define 
the invention or the application, which only is measured by the claims, 
nor is it intended to be limiting as to the scope of the invention in any 
way. 
It is therefore an object of the present invention to provide a new and 
improved internal combustion engine which has all of the advantages of the 
prior art and none of the disadvantages. 
It is another object of the present invention to provide a new an improved 
internal combustion engine which may be easily and efficiently 
manufactured and marketed. 
It is a further objective of the present invention to provide a new and 
improved internal combustion engine which is of durable and reliable 
construction. 
An even further object of the present invention is to provide a new and 
improved internal combustion engine which is susceptible of a low cost of 
manufacture with regard to both materials and labor, and which accordingly 
is then susceptible of low prices of sale to the consuming public, thereby 
making such internal combustion engine available to the buying public. 
Still yet a further object of the present invention is to provide a new and 
improved internal combustion engine that has greatly improved efficiency. 
It is still a further object of the present invention is to provide a new 
and improved internal combustion engine that has no moving crank shaft or 
other parts when the engine is in idle. 
Still a further object of the present invention is to provide a new and 
improved internal combustion engine that requires no cooling radiator. 
These together with still other objects of the invention, along with the 
various features of novelty which characterize the invention, are pointed 
out with particularity in the claims annexed to and forming a part of this 
disclosure. For a better understanding of the invention, its operating 
advantages and the specific objects attained by its uses, reference should 
be had to the accompanying drawings and descriptive matter in which there 
are illustrated preferred embodiments of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
With reference now to the drawings, a new and improved internal combustion 
engine embodying the principles and concepts of the present invention will 
be described. 
Referring initially to FIG. 1, the general organization of the internal 
combustion engine of the present invention is schematically illustrated. 
In the exemplary embodiment shown, the engine represented generally by 
reference numeral 10 has two cylinders each of which operates on the well 
known two-stroke principal. That is, on the intake or power stroke, the 
exhaust valve is closed, the intake valve is open for a predetermined 
portion of the stroke, and the spark plug or other ignition device is 
fired when the intake valve closes; whereas on the exhaust stroke, the 
piston returns to its top dead center position and at a predetermined 
portion of the stroke, the exhaust valve opens. The cycle is then 
repeated. In the second cylinder, the same sequence occurs, but one 
hundred eighty degrees out of phase. 
As schematically depicted in FIG. 1, the cylinder head 12 for both 
cylinders includes a pair of intake ducts 14, 14a, a pair of exhaust ducts 
16, 16a, separate pairs of intake and exhaust valve assemblies 18, 20 and 
18a, 20a, respectively. The cylinder head is suitably mounted on and 
generally above the engine block which defines a pair of cylinders 22, 22a 
in each of which a piston head and piston rod assembly is suitably mounted 
by conventional piston rings for up and down travel along the longitudinal 
axis of each cylinder, respectively. 
In accordance with the present invention, instead of connecting each piston 
rod to a rotatable crank or crank shaft at the bottom thereof, each piston 
rod is directly coupled through a manifold 27 to a corresponding piston 
assembly in hydraulic cylinders 24, 24a, respectively. Each hydraulic 
cylinder produces a high pressure output in hydraulic lines 26, 26a in 
response to downward movement of the piston in cylinders 22, 22a, 
respectively. Hydraulic lines 26, 26a are connected to a solenoid 
operated, hydraulic switching valve 28 which, in turn, is connected by a 
further pair of hydraulic lines 30, 32 to a conventional hydraulic motor 
34 having a rotatable output shaft 36. Thus, the power output represented 
by the rotation of shaft 36 is the power output of the engine of the 
present invention. As well known by those of ordinary skill in the engine 
art, shaft 36 may be coupled to suitable transmission means (not shown), 
the details of which are outside the scope of the present invention, to 
facilitate performing useful work such as powering a vehicle, boat, and 
the like. 
The solenoid which controls hydraulic valve 28 is actuated such that in one 
condition thereof determined by the TDC position of the piston in cylinder 
22, high pressure hydraulic fluid flows from cylinder 24 through lines 26 
and 30 to the input side of hydraulic motor 34, then through lines 32, 26a 
to hydraulic cylinder 24a. Then, when the piston in second cylinder 22a 
reaches TDC, the solenoid is actuated to a second condition whereupon 
valve 28 is reversed so that high pressure hydraulic fluid circuit is 
established through lines 26a, 30, 32, and 26. Hence, by the action of 
hydraulic valve 28, the direction of rotation of shaft 36 may be 
maintained as the pistons travel up and down in cylinders 22, 22a. The 
electrical signals applied to the hydraulic valve solenoid are derived 
from the engine's central computer as will be explained in more detail 
below. 
In accordance with another feature of the present invention, a continuous 
belt driven by a suitable sprocket on engine output shaft 36 drives a 
conventional rotary air compressor 38 the output of which is applied 
through duct 42 to oil separating tank 44 which removes most, but not all 
oil injected into the high pressure air stream by compressor 38. The small 
quantity of oil remaining in the high pressure air output traveling along 
duct 46 and then into air tank 48 ultimately serves to lubricate the 
intake and exhaust valves and the piston rings in the combustion chambers 
of main cylinders cylinder head 12 and main cylinders 22 and 22a. Air tank 
48 serves as a reservoir for high pressure air which latter is used for 
two purposes, namely, i) as a component of the explosive fuel air mixture 
fed through the intake valves into the main cylinders 22 and 22a, and ii) 
as the working fluid to actuate the intake and exhaust valves. Thus, 
suitable connections extend between the air tank 48 and intake ducts 14, 
14a; and between the air tank and the cylinder head 12, respectively. A 
conventional fuel pump (not shown) delivers gasoline or other combustible 
liquid fuel a duct which, in turn, is connected to an injector suitably 
located in the wall of cylinder head 12 and opening into the manifold or 
duct leading to intake valves 18, 18a. Preferably, air tank 48 is fitted 
with a series of intercooler tubes 50 for maintaining the pressure of the 
air in tank 48 below a predetermined maximum. It will be appreciated that 
the rotary screw compressor 38 which compresses the air to feed into the 
combustion chamber of each main cylinder and which provides the working 
fluid for actuating the intake and exhaust valves consumes only a 
relatively small fraction of the useful output of engine 10, say on the 
order of about 10% to about 15%. 
FIG. 2 shows a schematic diagram of the control system of the internal 
combustion engine 10 according to the invention. A digital computer 60 is 
suitably connected to a standard LSI battery 62 and is suitably adapted to 
receive several input signals and process these in accordance with 
instructions stored in the computer's internal memory so to control the 
operation of the various components described above in connection with 
FIG. 1 in their desired extent and sequence. Thus, signals from the 
engine's throttle are transmitted to the computer 60 along with signals 
from potentiometer 25, 25a indicating the instantaneous position of each 
cylinder head in each main cylinder whereupon this information is 
automatically processed by the computer to develop appropriate output 
signals to actuate the solenoids for the intake and exhaust valves, the 
hydraulic reversing valve 28 and other crucial engine functions all in 
accordance with pre-programmed instructions stored in the computer. 
A manually operable power switch 64 may also be provided adapted to 
override the computer's automatic or default instructions and maintain the 
intake valve of each main cylinder open for a longer or shorter period of 
time than the default setting. Thus, if computer 60 is programmed to 
maintain the intake valves open for say, 10% of the intake stroke (e.g. 
the "default" condition), manual switch 64 may be actuated to increase the 
intake valve open interval to say, 30% of the intake stroke thereby 
increasing the power output of the engine. 
Computer 60 may suitably be programmed to automatically perform other 
engine functions including, but not limited to providing proper timing 
signals for the water injection pump (to be described in more detail 
below); to provide proper timing signals for actuating the engine's spark 
plug coil, and so on. In respect to the present disclosure, it will be 
understood that computer 60 is a conventional general purpose programmable 
digital computer comprising a microprocessor, random access memory, 
control circuitry, analog-to-digital and digital-to-analog converters, and 
so on, the particular details of construction and operation of which are 
well known and outside the scope of the present invention. 
As mentioned above, an important feature of the present invention is the 
lack of a rotating crank shaft and the need to use a friction producing 
mechanical rocker arm assembly to actuate the intake and exhaust valves. 
Turning to FIG. 3, the novel valve actuation means of the invention are 
shown. Intake valve 18 comprises a stem 72 attached to a piston 74 at the 
top distal end thereof. Piston 74 is adapted for up and down travel in an 
air cylinder 76. A pair of passageways 78, 80 in the sidewall of cylinder 
head 12 are connected to a solenoid air valve 82 which functions in 
response to appropriate timing signals from computer 60 to permit high 
pressure air fed from tank 48 to valve 80 to flow through air passages 78, 
80 on either side of air piston 74 thereby to control the up and down 
travel of valve stem 72 and the operation of intake valve 20 in a manner 
believed apparent. 
Similarly, exhaust valve 20 comprises a stem 72a attached to a piston 74a 
at the latter's distal top end. Piston 74a is adapted for up and down 
travel in an air cylinder 76a. A pair of passageways 78a, 80a in the 
sidewall of cylinder head 12 are connected to a solenoid air valve 82a 
(identical to solenoid valve 82) which functions in response to 
appropriate timing signals from computer 60 to permit high pressure air 
fed from tank 48 to valve 80a to flow through air passages 78a, 80a on 
either side of air piston 74a thereby to control the up and down travel of 
valve stem 72 and the operation of exhaust valve 20. 
It thus will be appreciated that under control of computer 60, solenoid air 
valves 82, 82a function to actuate intake and exhaust valves 18, 20 in a 
proper timed sequence depending upon throttle opening, the instantaneous 
position of main piston head 90 and piston rod 92 in cylinder 22 (as 
sensed by linear potentiometer 25) and other factors (e.g. manifold 
pressure in cylinder head 12) applied to computer 60 in the form of 
electrical input signals so as to achieve maximum power output and 
operating efficiency. More importantly, in accordance with the operating 
principals of the engine of the present invention when the throttle is 
completely closed, the engine is in idle with no rotating crank shaft, 
i.e. the output shaft 36 of hydraulic motor is stationary and all other 
parts are in a "stand still" condition. This mode of operation constitutes 
an obvious, substantial efficiency advantage over conventional "rotating 
crank" internal combustion engines. 
Turning to FIG. 4, there is shown the preferred arrangement for mounting a 
spark plug assembly in cylinder head 12. Spark plug 100 is threadedly 
received in a complimentary female threaded port 102 communicating with 
main combustion chamber 104 substantially as shown. A conductor 106 
extends from spark plug 100 to ignition coil 108 which latter is 
conveniently and suitably mounted near cylinder head 12. Although computer 
60 is capable of generating electronic ignition signals to "energize" coil 
108 through an appropriate relay or breaker switch, an alternatively 
preferred method is contemplated wherein the coil is actuated directly by 
the position of the intake valve 18. Such alternatively preferred means 
comprises an extension or rod 110 affixed to the top of air piston 74 and 
adapted for slidable up and down travel in an opening 112 in cylinder head 
12 which latter is sealed against air leakage by packing 114. The distal 
end or tip of rod 110 bears against a leaf spring breaker arm 114 
cantilever mounted on insulated block 116 by screw 118. The end of breaker 
arm 114 terminates in a contact 120 adapted to engage similar contact 122 
carried on insulated mounting block 124. Contact 122 is suitably connected 
to ground. When intake valve 18 is closed, rod 110 will open the contacts 
120, 122 energizing coil 108 and firing spark plug 100 thereby initiating 
the power stroke by combustion of the fuel air charge in combustion 
chamber 104. During the exhaust stroke, valve 18 remains closed, contacts 
120 and 122 are engaged and the coil's capacitor is charged for the next 
cycle. The coil will not fire the spark plug again until the beginning of 
the power stroke when valve 18 once again closes. In use, it will be 
apparent that the mechanical circuit breaker system just described will be 
fitted one to each cylinder of the engine. 
FIG. 5 depicts a conventional fuel injector 130 suitably mounted in the 
wall of intake manifold 132. The injector is controlled by computer 60 to 
charge the high pressure airstream from tank 48 with an optimum quantity 
of fuel after intake valve 18 has been opened at the beginning of the 
power stroke. 
Still another important advantage of the internal combustion engine of the 
present invention is that the need for a conventional radiator cooling 
system is obviated. While it is necessary to prevent overheating within 
each combustion chamber due to the fact that the fuel/air mixture is 
compressed, this may be accomplished with the relatively simple means 
depicted in FIG. 6. As shown therein, a conventional water jet injector 
140 is suitably mounted in the cylinder head wall such that the nozzle 
thereof opens into exhaust manifold 142. Although not shown, it will be 
understood that injector 140 is suitable connected to a supply tank of 
water by a flexible conduit or hose and that a water pump is 
interconnected with the hose so that when actuated by an appropriate 
timing signal from computer 60 (see FIG. 2), a pulse of pressure is 
applied along the hose sufficient to inject a predetermined quantity of 
water into combustion chamber 104 when exhaust valve 20 is open. In 
addition, the top surface of main piston 90 is provided with a concavity 
or dished portion 144 substantially as depicted to serve as a reservoir 
for the injected amount of water. As the piston is caused to begin its 
power stroke and the spark plug fires, the water in concavity 144 will 
vaporize effectively lowering the maximum combustion temperature that 
would otherwise appertain in the absence of water injection according to 
the present invention. 
The use and operation of the internal combustion engine of the invention is 
believed apparent from the above description. 
From the foregoing, it is evident that a new and improved internal 
combustion engine has been disclosed as required by statute and which has 
greatly improved efficiency, is relatively low in cost to build, use and 
maintain, that has no moving crank shaft or other parts when the engine is 
in idle, and that requires no cooling radiator system. 
With respect to the above description, it should be realized that the 
optimum dimensional relationships for the parts of the invention, to 
include variations in size, materials, shape, form, function and manner of 
operation, assembly and use, are deemed readily apparent and obvious to 
those skilled in the art, and therefore, all relationships equivalent to 
those illustrated in the drawings and described in the specification are 
intended to be encompassed only by the scope of appended claims. 
While the present invention has been shown in the drawings and fully 
described above with particularity and detail in connection with what is 
presently deemed to be the most practical and preferred embodiment(s) of 
the invention, it will be apparent to those of ordinary skill in the art 
that many modifications thereof may be made without departing from the 
principles and concepts set forth herein. 
Hence, the proper scope of the present invention should be determined only 
by the broadest interpretation of the appended claims so as encompass all 
such modifications and equivalents.