Pumps – Processes – Of pumping one fluid by contact or entrainment with another
Reexamination Certificate
1995-10-10
2001-06-12
Freay, Charles G. (Department: 3746)
Pumps
Processes
Of pumping one fluid by contact or entrainment with another
C417S065000, C417S187000
Reexamination Certificate
active
06244826
ABSTRACT:
FIELD OF THE INVENTION
This invention is related to methods and apparatus for using a first gas to compress or suction out a second gas.
BACKGROUND OF THE INVENTION
Present day four-stroke internal combustion (IC) engines employ a solid piston moving to and fro inside a cylindrical bore, to perform the four operations, viz., (i) suction, (ii) compression, (iii) power and (iv) exhaust. The present day two-stroke IC engines do the first three of the above four operations by solid piston only, the only difference being in that the crankcase side of the piston is used for an intake or suction operation, so that while the solid piston is doing compression on one side it is doing suction on the other side.
The fourth operation, viz., the exhaust, done in present-day 2-stroke IC engines, may be viewed with interest to compare with the present invention in the sense that two dissimilar gases in direct contact result in filling the closed chamber with gaseous medium. Though the above exhaust process may also be called as partial gaseous piston method, the present invention differs fundamentally in the method and purpose, the details and the novelty of which have been given below.
More generally, present-day reciprocating air-compressors employ a solid piston moving inside a cylindrical bore to perform suction and compression alternatively. However, a solid piston reciprocating in a closed chamber presents various problems of cost and inefficiency. Bore and piston have to be precisely machined and sealing rings are necessary for effective sealing, and loss of power due to friction is high because of the sliding piston. A heavy lubrication system is required for the sliding piston, and a heavy cooling system is necessary because the piston will seize if the equipment runs at elevated temperatures. Because of the heavy cooling system, loss of heat energy in cooling water or air is high. Wear and tear of bore and piston necessitates frequent maintenance or replacement of parts like the sleeve, piston rings, etc. Vibration (due to unbalanced reciprocating mass) and noise are high.
Limitations of existing solid-piston IC engines also are known. Because the stroke and the clearance volume are fixed, the compression ratio of the engine is fixed. In other words, the suction and compression pressures are almost fixed for a given speed of the engine. Because of the above points, an engine designed for a specific fuel, e.g. gasoline, cannot be easily altered for other fuels like diesel or LPG (Liquid Petroleum Gas).
The power of a solid-piston IC engine is dependent on the speed to a great extent. In fact, while the actual requirement in most of the applications is high-torque at low speed and lower-torque at high speed, the IC engine delivers power the other way. Moreover, the engine is capable of delivering power only within a specified range of RPM; there is an idling speed and a maximum speed. It cannot deliver power at zero RPM like a steam engine. In order to be ready for delivering power, the engine has to run at idling speed, wasting fuel.
The solid-piston engine gives acceptable performance (both fuel economy-wise as well as torque capacity-wise) only within a narrow bandwidth of the engine speed. This fact necessitates accessories like a clutch and gear system to obtain the same power at low as well as high output speeds, at the wheels of the vehicle. Moreover, the engine starting apparatus is heavy and quite costly due to high frictional torque and the high idling speed. The ignition timing, the rate of combustion, and the velocity and position of pistons must be coordinated failing which, problems like pre-ignition, knocking, etc., arise.
DESCRIPTION OF RELATED ART
Relevant prior art includes U.S. Pat. No. 585,434 titled “Explosive Engine”, which uses a compressed air-fuel mixture in the crank case to push (positive pressure) the burnt gases out of the combustion chamber. The present invention is the opposite, i.e., a flowing gas which may be burnt gas itself sucks (negative pressure) the air-fuel mixture into the combustion chamber. In the present invention the air-fuel mixture (which is the gaseous medium of a thermodynamic cycle) is the passive gas, and the burnt gas (gaseous piston) is the active gas, during scavenging. In the above patent, it is the other way, i.e., the air-fuel mixture is the active gas while the burnt gas is the passive gas. In other words, the present invention is about a method to perform suction or compression wholly on the medium of thermodynamic process.
In the above patent, the air-fuel mixture, which is the medium of thermodynamic process, does not undergo suction or compression by another gas. Instead, it undergoes suction first in the crankcase, then compression in the crankcase, and then compression once again in the cylinder, all the time done by the solid piston only. Also, regarding the burnt gas present in the cylinder during scavenging it has already undergone and completed the three thermodynamic processes, viz., compression, heat addition, and expansion, and is now a product of waste which just has to be removed. A substantial portion of the burnt gas has already left, due to advanced valve or port opening, which leaves only a fraction of the mass of original gas taken for the cycle.
The definition of closed chamber gas equipment calls for a fixed mass of gaseous medium throughout the thermodynamic cycle. Here, the mass of burnt gas is reduced from that involved in the cycle. Hence the burnt gases can no longer be called as gaseous medium of the thermodynamic process. The process of scavenging the burnt gas is not done wholly but done in part, since part of the burnt gas leaves by itself out of the cylinder as mentioned above.
U.S Pat. No. 3,695,238 tided “IC Engine Exhaust Gas Discharge System” uses an exhaust receiver connecting the exhaust ports of two cylinders and uses wave reflections to enhance the compression and exhaust operations to increase the engine efficiency. The exhaust gas does not perform wholly any one of the compression or exhaust operations but merely enhances the said operations done by solid piston method.
U.S. Pat. No. 1,733,431 titled “Internal Combustion Engine” solves the problem of condensation of fuel in the crankcase of a two-stroke engine by admitting air compressed in the crankcase through the carburetor to the combustion chamber, and also increases the pressure at the suction stroke to superatmospheric pressure. Hence, even though this method delivers superatmospheric pressure gas to the combustion chamber to increase the compression pressure of the engine, this method does not by itself replace the solid piston by an element to do the compression operation.
The same can be said of any prior turbo-charged or supercharged engines such as shown in U.S. Pat. No. 2,853,987 titled “Diesel Engine Supercharged By The Aero-Dynamic Wave Machine”, where direct exchange of energy between intake gas and burnt gas is disclosed but only to increase the suction pressure and not to replace the solid piston for the suction process.
U.S. Pat. No. 2,446,094 titled “Supercharging and Scavenging IC Engines” discloses pairs of tubes generating jets of gases but again, not to replace the solid piston in the suction and compression processes but only to assist the solid piston further in the said operations.
A Sterling-liquid piston engine used liquid colum in U-tubes as a substitute for solid piston. Though that engine has technical and commercial problems, it proved that solid is not the only form for making pistons.
OBJECTS OF THE INVENTION
The objects of the present invention are to provide an improved method and apparatus for compressing a gaseous medium.
More particularly, other objects of the present invention are:
to reduce or remove the problems arising out of solid piston method in the aspects of cost, maintenance, nuisance, efficiency and weight as stated herein;
to counter some of the limitations arising in the existing IC engines as described above;
to eliminate one or more of the parts of an automobile like the clutch and
Freay Charles G.
Jones & Askew LLP
LandOfFree
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