Four-cycle internal combustion engine with curtailed intake process

Abstract

A four-cycle internal combustion engine has a permanent curtailed intake process, which allows the temperature and pressure of intake air to the combustion cylinders to be tightly controlled, and enables a very small combustion chamber so that a much higher compression ratio and pre-ignition compression pressure can be achieved without approaching the air/fuel mixture auto-ignition threshold. The maximum threshold of curtailed intake volume is determined to be 68% of engine cylinder volume to achieve a compression ratio CR of 22.1 or higher. Because this design can effectively regulate and set the maximum pre-ignition temperature of the fuel-air mixture, it can combust virtually any type of liquid hydrocarbon fuel without knocking. This four-cycle engine, due to its higher compression ratio, generates power equivalent to or greater than a standard four-cycle engine in a smaller and lighter engine and at a much higher efficiency.

Claims

1. A four-cycle spark ignition Curtailed Intake Process internal combustion engine comprising: one or more combustion cylinders, each cylinder having a total cylinder volume, a top dead center (TDC) and a bottom dead center (BDC), and each cylinder having one or more intake valves, and each cylinder containing an axially reciprocating piston mechanically connected to a crankshaft and a flywheel, wherein each cylinder is configured to execute a four-cycle combustion process, comprising a permanent curtailed intake cycle that requires a minimized combustion chamber volume corresponding to an engine compression ratio (CR) of 22.1 or higher, during which curtailed intake cycle one or more of the intake valves remain open and the piston moves axially from the TDC of the cylinder through a crankshaft intake angle interval and draws a curtailed intake volume of an air-fuel mixture through the intake valves into the cylinder, followed by a compression cycle, during which all intake valves are closed and the piston moves axially toward the TDC of the cylinder and compresses the air-fuel mixture to a pre-ignition compression volume, which is equal to the combustion chamber volume, a pre-ignition compression pressure, and a pre-ignition compression temperature, followed by a spark ignition of the air-fuel mixture, which drives the piston toward the BDC of the cylinder in an expansion cycle, followed by an exhaust cycle, during which the piston moves toward the TDC of the cylinder and drives an exhaust gas out of the cylinder ahead of a next intake cycle, and wherein the total cylinder volume of each combustion cylinder is a volume of the cylinder with the piston at BDC, and wherein the combustion chamber volume of each combustion cylinder is a volume of the cylinder with the piston at TDC, and wherein a ratio of the total cylinder volume to the combustion chamber volume defines the compression ratio CR, and wherein the CR is at least 22.1, and wherein the CR of 22.1 results in a relatively lower engine efficiency, while the CR greater than 22.1 results in a relatively higher engine efficiency; wherein the crankshaft intake angle size is configured to minimize the size of the combustion chamber and thereby maximize the pre-ignition compression pressure and the compression ratio CR while maintaining the pre-ignition compression temperature at a level below an auto-ignition temperature of a selected fuel, and: wherein a combination of the compression ratio CR of at least 22.1 and a curtailed intake cycle maximizes the engine efficiency.

2. The engine of claim 1, wherein the crankshaft intake angle interval is at a value at which a ratio of the curtailed intake volume to the total cylinder volume is equal or less than 0.68.

3. The engine of claim 2, wherein the intake valves are configured either to open at a crankshaft angle at or near 0 and close at a crankshaft angle of 110 or less, or to close at a crankshaft angle of 250 or greater.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic diagram illustrating the four-cycle combustion process of the present invention for a 4 cycle engine with suggested curtailed intake process.

(2) FIG. 2 is a schematic diagram illustrating a four-cycle combustion process of the present invention for a 4 cycle optimal CIP engine with 55% curtailed intake process and 29.4 compression ratio.

(3) FIG. 3 is an exemplary P-V diagrams for a four-cycle standard naturally aspirated single-cylinder combustion process with a compression ratio CR=10 and volume engine cylinder size V.sub.e=1 Liter.

(4) FIG. 3A is an exemplary superimposed P-V diagrams for a four-cycle standard naturally aspirated single-cylinder combustion process with a compression ratio CR=10 and volume engine cylinder size V.sub.e=1 Liter.

(5) FIG. 4 is an exemplary P-V diagrams for a four-cycle CIP single-cylinder combustion process with a compression ratio CR=29.4, curtailed intake volume V.sub.t=0.55 Liter and volume engine cylinder size V.sub.e=1 Liter.

(6) FIG. 4A is an exemplary superimposed P-V diagrams for a four-cycle CIP single-cylinder combustion process with a compression ratio CR=29.4, curtailed intake volume V.sub.t=0.55 Liter and volume engine cylinder size V.sub.e=1 Liter.

DETAILED DESCRIPTIONS OF THE PREFERRED EMBODIMENTS

(7) Referring to FIG. 1, is a four-cycle, 1 Liter single-cylinder combustion process diagram 1 with curtailed intake process, comprising a short or curtailed intake process recommended maximum crankshaft angular range selection 4 (0-<110/>250) for the curtailed intake process that will result in a curtailed compression process, a maximum recommended curtailed compression process 7 (250-360), hot gas expansion process 5 (360-540) and exhaust process 6 (540-0) of crankshaft angular position, with a compression ratio CR 3 of recommended range of 22:1 or higher and a recommended combustion chamber volume size 2 range volume smaller than 0.045 of engine cylinder volume.

(8) Referring to FIG. 2, is a diagram of an optimal recommended four-cycle, 1 Liter single-cylinder volume combustion process diagram 1 with curtailed intake process, comprising a short or curtailed intake process 4 (0-<94/>266), a compression process 7 (266-360), hot gas expansion process 5 (360-540) and exhaust process 6 (540-0) of crankshaft position angle, with a compression ratio CR 3 of 29.4:1 and combustion chamber volume size 2 of 0.034 engine cylinder volume size and a detailed script of each process angular rotation position 8.

(9) FIGS. 3 and 3A represent the P-V diagrams 12 and superimposed P-V diagram 13 of a standard naturally aspirated SI, 1 Liter engine with CR=10, where:

(10) awork spent by the engine on compression=2.30PV/cycle,

(11) bwork gained by engine on expansion=6.86PV/cycle,

(12) cwork that cannot be captured on exhaust and it is lost=2.52PV/cycle,

(13) dheat applied to the engine by burning fuel which increases the pressure by 2.75 times,

(14) ework balance gained by engine=4.56PV/cycle.

(15) Simplified efficiency of this engine is: E=4.56/7.08=64%

(16) While, FIGS. 4 and 4A represent the P-V diagrams 14 and superimposed P-V diagram 15 of a CIP 1 Liter engine with CR=29.4, where:

(17) awork spent by the engine on compression=1.88PV/cycle,

(18) bwork gained by engine on expansion=6.135PV/cycle,

(19) cwork that cannot be captured on exhaust and it is lost=0.27PV/cycle,

(20) dheat applied to the engine by burning fuel which increases the pressure by 2.75 times,

(21) ework balance gained by engine=4.255PV/cycle.

(22) Simplified efficiency of this engine is: E=4.255/4.525=94%

(23) Efficiency Comparisons Between Standard and CIP Engines

(24) Considering FIGS. 3 and 3A, are P-V diagrams for a four-cycle naturally aspirated standard single-cylinder combustion process 12 and 13 with a compression ratio CR=10 and volume engine cylinder size V.sub.e=1 Liter. Hypothetical expansion engine volume of 2.18 Liters represents a non-existent expansion displayed for the purpose of evaluation. As it can be seen by this P-V diagram the temperature for a standard engine at the end of expansion cycle is about 1,075 K or 802 C. and a pressure of exhaust gases of about 2.75 bars.

(25) Considering FIG. 4 and FIG. 4A, are P-V diagrams for a four-cycle optimal CIP engine combustion process 14 and 15 with a compression ratio CR=29.4 and volume engine cylinder size V.sub.e=1 Liter. Being that this CIP engine has the process of intake end at 0.55 volume and the compression start at that point as well, from P-V diagram can be seen that work in compression for this engine is 1.88PV/cycle, which when compared is less than that of a standard engine which spends a work in compression equal to 2.30PV/cycle for a comparable work output (e), 4.56PV/cycle for a standard engine and 4.255PV/cycle for a CIP engine. The temperature of a CIP engine is 756 K or 483 C. and a pressure of 1.26 Bars of exhaust gases at the end of the expansion process which are both much less than that of a standard engine.

(26) As illustrated by the foregoing P-V diagrams, the efficiency of the four-cycle CIP engine exceeds that of the standard SI-ICE engine.

(27) Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that many additions, modifications and substitutions are possible, without departing from the scope and spirit of the present invention as defined by the accompanying claims.

(28) As used hereinabove and in the following claims, the term Top Dead Center (TDC) means the piston's closest position to the cylinder head, corresponding to a crankshaft angle of 0 or 360, and the term Bottom Dead Center (BDC) means the piston's farthest position from the cylinder head, corresponding to a crankshaft angle of 180. Total cylinder volume means the volume of the cylinder when the piston is at BDC, and the combustion chamber volume means the volume of the cylinder when piston is at TDC.