CA2879253A1 - Hybrid split cycle internal combustion engine - Google Patents

Abstract

The invention is a hybrid between a single cylinder 2 stroke pump and a single cylinder 2 stroke 4 cycle internal combustion engine. The pump and the 2 stroke engine have cylinder head that have a passageway connection. The invention uses 2 strokes of the pump plus the simultaneous 2 strokes of the engine to circulate fresh air through the two cylinders and back to the atmosphere. It uses 5 cycles which are divided into stages and 2 strokes of 2 pistons happening simultaneously inside separate cylinders to turn its crankshaft one complete revolution.
An air transfer cycle is added to the conventional 4 cycles of internal combustion.

Description

Hybrid Split Cycle Internal Combustion Engine Field of Invention The invention relates to a hybrid engine between two devices: a single cylinder 2 stroke pump and a single cylinder 2 stroke 4 cycle internal combustion engine. The invention also relates to 5 cycles instead of the conventional 4 cycles of internal combustion and a novel method of subdividing 4 of the 5 cycles into stages and the use of a redesigned cylinder heads, a redesigned crankshaft and corresponding camshaft to allocate these stages to be performed in either the pump cylinder and/or the engine cylinder. The invention is expected to run in spark ignition or compression ignition mode.
The invention also relates to 2-stroke and 4-stroke internal combustion engines.
For the rest of this document, the invention is referred to as the Hybrid Engine.
Background Internal Combustion Engine Sub-Assemblies Generally two or three sub-assemblies make up an internal combustion engine: Shown in Figure 1 is a cylinder head sub-assembly (A), a cylinder block (B) and a crankcase block (C) of a 4 stroke split cycle internal combustion engine. The crankcase houses a crankshaft (19) with at least one crank throw (18). The cylinder block houses at least one cylinder bore (5 &
13). One end of the bore is covered by a cap known in the industry as the cylinder head. The cylinder bore houses at least one piston (3 & 11) with compression rings around it. The top of the piston, known as the crown, the walls of the cylinder and the cylinder head defines a space in the cylinder known as the combustion chamber (16). A rod (17) connecting the piston to the crank throw (18) enables the mechanical conversion of the lateral up and down stroke of the expansion piston (11) into 360 degree circular motion of the crankshaft (19) which in turn causes the up and down movement of the compression piston (4).
Four Cycles of Internal Combustion Engine Four steps or cycles govern the operation of an internal combustion engine.
1. Mixture of air and fuel is delivered inside a chamber or cylinder, then

2. Compressed, then

3. Made to combust inside the combustion chamber, then

4. Smoke and other combustion by-products are exhausted from the combustion chamber.
They are known in the industry as intake, compression, combustion and exhaust cycles.
Strokes and Cycles The boundary and duration of a stroke is conventionally defined by the top and bottom spots where the piston reverses directions in its up and down or left and right travel inside the cylinder. These are respectively known in the industry as top dead center (TDC) and bottom dead center (BDC).
The conventional 4 stroke internal combustion design has one cylinder head sub-assembly consisting of valves, camshafts, belts and gears. One stroke is assigned to each of the 4 cycles and 4 strokes are required to turn a crankshaft one complete revolution.
The conventional 2 stroke internal combustion design does not have a cylinder head. It has exhaust and intake ports in the cylinder wall Instead of intake and exhaust valves. This arrangement allows it to combine the intake and compression cycles in one stroke and combustion and exhaust cycles in another. With no cylinder head, 2-stroke engine turns its crankshaft one complete revolution in 2 strokes of its piston. The light small footprint makes it the engine of choice in motorcycles, garden tools, lawnmowers and motor boats where small housing is a definite advantage.
Ignition and Fuels In addition to strokes and cycles, internal combustion engines are classified based on the type of fuel and the type of combustion. Spark ignition in 4 stroke internal combustion engines are mostly found in motorcycles, cars and aircrafts which use gasoline or kerosene as fuel.
Buses, trucks, locomotives stationary generating plants and large marine engines use the 2 stroke internal combustion design to provide high compression ignition of diesel fuel.
Scavenging - Exhaust Gas Out, Fresh Air In Scavenging is the process of pushing exhausted gas-charge out of the combustion chamber and drawing in a fresh draught of air or air/fuel mixture for the next cycle.
In a 4 stroke internal combustion engine, this is accomplished using 2 strokes, the exhaust stroke and the intake stroke respectively. In a 2 stroke internal combustion engine the exhaust cycle and the intake cycle overlap when both the intake and exhaust ports are open.
This generally results in a small but not so insignificant amount of unburned air/fuel escaping out into the atmosphere. Small 2 stroke internal combustion engines using a mixture of gasoline and crank case oil for fuel and lubrication, which produces exhaust gases containing higher amount of unburned hydrocarbons. This type of 2 stroke scavenging is expensive and injures the environment.
Attached Auxiliary Devices A high engine temperature from combustion and friction between moving metallic parts must be maintained below a specific threshold to minimize engine wear and tear and to keep the engine running efficiently. Driven by the engine's crankshaft, the 4 stroke internal combustion engine employs auxiliary devices like fans and pumps to circulate air, oil and water around the engine block.

To help improve the engine's efficiency and power, modern internal combustion engines use exhaust gas in turbo charger and exhaust gas recirculation valve. Driven the engine's exhaust gas a turbo charger is a turbine that forces extra air into the combustion chamber. As the name suggests, the exhaust gas recirculation valve re-circulates some of the hot exhaust gas back into the combustion chamber.
The two-stroke engine with compression ignition is also favored in large marine engines and stationary power-generating plants that require dependable long hours of continuous operation. The use of diesel fuel to reduce operating costs is also a factor. The 4 stroke 4 cycle spark ignition design using gasoline for fuel is none the less used in in cars and aircrafts.
Air cooled small 2 stroke internal combustion engines in motorcycles, motor boats and the home and garden appliances do not use auxiliary devices.
Split Cycle Internal Combustion Engine The split cycle 4 stroke internal combustion engine divides the four internal combustion cycles into two groups of two cycles and assigns each group to an expansion cylinder and a compression cylinder. The split cycle engine has a cylinder head with camshaft and uses 2 strokes of the expansion piston and 2 strokes of the compression piston simultaneously for a combined total of 4 strokes. Similar to a conventional 2 stroke internal combustion engine, a split cycle engine turns the crankshaft in 2 strokes, 50% more efficient than the conventional 4 stroke internal combustion engine. A four, six or eight cylinder split cycle 4 stroke internal combustion spark ignition engine will require 50% less fuel injectors and 50% fewer spark plugs than their conventional 4 stroke internal combustion spark ignition engine having an equal number of cylinders.
Dugald Clerk Engine, the first Supercharger Development of the internal combustion engine dates back to 1800. A
patent was rewarded to the Otto 4 stoke 4 cycle of internal combustion. In getting around the Otto patent, Dugald Clerk developed a 2 stoke equivalent.
There is no record of a patent rewarded to Dugald Clerk or the Clerk cycle.
From the Wikipedia:
"Clerk's engine was made of two cylinders ¨ one working cylinder and an additional cylinder to charge the cylinder, expelling the exhaust through a port uncovered by the piston. Some sources consider this additional cylinder the world's first supercharger. Clerk himself states that "It is not a compressing pump, and is not intended to compress before introduction into the motor, but merely to exercise force enough to pass the gases through the lift valve into the motor cylinder, and there displace the burnt gases, discharging them into the exhaust pipe." Hence sources recognise it instead as a "pumping cylinder", pointing out that it did not actually compress the fuel-air mixture, it simply moved the fresh mixture to the working cylinder to force out the gasses burnt previously Dugald Clerk describes a Cambell engine as using his cycle, as follows: "It has two cylinders, respectively pump and motor, driven from cranks placed at almost right angles to each other, the pump crank leading. The pump takes in a charge of gas and air, and the motor piston overruns a port in the side of the cylinder at the out-end of its stroke to discharge the exhaust gases. When the pressure in the motor cylinder has fallen to atmosphere, the pump forces its charge into the back cover of the motor cylinder through a check valve, displacing before it the products of combustion through an exhaust port; the motor piston then returns, compressing the contents of the cylinder into the compression space. The charge is then fired and the piston performs its working stroke. This is the Clerk cycle."
Typical Split Cycle Configuration Figure 1 shows a cylinder head block (A), cylinder block (B) and crank case (C) configuration of a typical split cycle engine. The cylinder block (A) in the

5 split-cycle internal combustion engine has two cylinder bores (5 &13) and corresponding cylinder head sub-assemblies. One set of bore and cylinder head sub-assembly is for an expansion cylinder (5) and another for a compression cylinder (13). The two cylinder head sub-assemblies have a passageway (15) connection controlled by a pressure check valve (6) and an outlet valve (7). The 4 cycles of internal combustion are split between the two cylinders.
Starting with the passageway control valve (7) in closed position, the two cylinders are uncoupled. The exhaust valve (8) of the expansion cylinder is closed and the intake valve (1) of the compression cylinder is open. From the previous combustion cycle, the expansion piston (11) is pushed down by the expanding hot gas turning the crankshaft. The compression cylinder (5) goes into intake cycle as the compression piston (3) is pulled down by circular motion of its crank throw, admitting air from the atmosphere and fuel from a fuel delivery sub-system. When the compression piston (3) reaches the bottom dead center (4) the intake valve (1) closes, the compression piston (5) reverses direction; it goes into the compression cycle putting the intake air/fuel mixture under pressure. As the expansion piston (11) reaches the bottom dead center (12), the exhaust valve (8) opens and the expansion piston (11) reverses direction; the expansion cylinder (13) goes into the exhaust cycle, the expansion piston (11) pushes the exhaust gas out of the cylinder. The intake valve (1) stays closed. At a preset time shortly before the compression piston (3) reaches top dead center (2), the exhaust valve (8) closes, the passageway control valve (6) opens and the pre-compressed air/fuel mixture in the compression cylinder (5) transfers to the expansion cylinder (13). The passageway control valve (7) closes and the pre-compressed air/fuel mixture is ignited. The expansion cylinder (13) goes into combustion cycle. The cycle repeats.
The Scuderi engine US patents US6543225, US6609371, US6722127, US6880502, US6952923, US6966329, US7017536, US7121236, US7588001, US7628126, US7810459, US7954461,US7954463, US8006656, US20110220075, US20110220077, of the Scuderi Group is the most recent

6 example of previous description of a 4 stroke split cycle internal combustion engine design.
Referring to Figure 1, a Scuderi engine is shown near the end of the exhaust stroke; the pressure check valves (6) and outlet valve (7) separating the compression cylinder (5) from the expansion cylinder (13 ) are closed and the expansion piston (11) is nearing its top dead center (9) leading the compression piston (3) still in the compression stroke. Before all the pre-compressed air/fuel mixture is completely transferred from the compression cylinder (5) into, and confined in, the combustion chamber (10) of the expansion cylinder (13), the expansion piston (11) will be way past the top dead center (9) and would already have reversed direction towards its bottom dead center (12). Igniting the spark plug (14) before the expansion piston (11) reaches top dead center (9) will not result in the desired combustion.
This explains the ignition taking place after the expansion piston (11) is past top dead center (9). This is contrary to the conventionally accepted and decade old practice in spark ignition engines of firing the spark plug a few degrees before the piston reaches top dead center. Ignition after top dead center is highly unusual and a probable cause for concern at high engine RPM.
Why Hybrid Engine Recent increases in the world oil and gas supply encouraged the continued used of the internal combustion as the primary source of power in the transportation industry. At the same time, public awareness of the negative impact of internal combustion technology on the environment has increased.
The majority of cars and trucks on the road today run on a 4 stroke 4 cycle 4 cylinder internal combustion engines.
A 4 cylinder Hybrid Engine is expected to have the same or smaller carbon and physical foot print.

7 The Hybrid Engine can be manufactured using the same environmentally friendly technologies and manufacturing facilities used for making the 4 cylinder 4 cycle 4 stroke engine.
The less costly Hybrid Engine requires fewer parts (50% less spark plug, 50%
less fuel injector and 25% less valve), turns its crankshaft in 50% fewer strokes (2 stroke of the pump piston and 2 strokes of the engine piston happening simultaneously).
Because of these characteristics the Hybrid Engine can be expected to be more fuel efficient and financially and environmentally friendly.
Brief Description of the Drawings Figure 1 ¨ Example of Scuderi Split Cycle 4 Stroke Engine at Exhaust Stroke Figure 2 ¨ Example Embodiment of the Hybrid Engine (Using 67.5 degrees Crank Throw Angle) Figure 3 ¨ Example Embodiment of the Hybrid Engine (Using 45 degrees Crank Throw Angle) Figure 4 ¨ Example Embodiment of the Hybrid Engine (Using 90 degrees Crank Throw Angle) Figure 5 ¨ 67.5 Degrees Crank Throw Positions at the Start of the Final Compression Stage Figure 6 ¨ 45 Degrees Crank Throw Positions at the Start of the Final Compression Stage Figure 7 ¨ 90 Degrees Crank Throw Positions at the Start of the Final Compression Stage Figure 8 ¨ Compression Valve Stem Seal Figure 9 ¨ Compression Plate

8 Figure 10 ¨ Early Air Intake Stage and Final Compression Stage Figure 11 ¨ Final Air Intake Stage and Start of Combustion Figure 12 ¨ Early Exhaust Stage and Early Air Transfer Stage Figure 13 ¨ Middle Exhaust Stage and Middle Air Transfer Stage Figure 14 ¨ Final Exhaust Stage and Middle Air Transfer Stage Figure 15 ¨ Early Compression Stage and Final Air Transfer Stage Brief Description of the Tables Table 1¨ Stages, Piston Directions and Valve Controls Using 67.5 Degrees Crank Throw Angle (refer to Figure 5 for Pump and Engine Crank Throws Positions) Table 2 ¨ Stages, Piston Directions and Valve Controls Using 45 Degrees Crank Throw Angle (refer to Figure 6 for Pump and Engine Crank Throws Positions) Table 3 ¨ Stages, Piston Directions and Valve Controls Using 67.5 Degrees Crank Throw Angle (refer to Figure 7 for Pump and Engine Crank Throws Positions) Table 4 ¨ Effect of Different Crank Throw Angles on Early Compression Stage and Final Compression Stage Detailed Description of the Hybrid Engine The Clerk engine, Scuderi engine and the Hybrid Engine in this invention, all have two cylinders one of which is the power, engine or expansion cylinder where combustion takes place. The second cylinder in the Scuderi engine

9 compresses the intake air; in the Clerk engine, it is a simple pump. In the Hybrid Engine the second cylinder serves as both a pump and a compressor hence it has a special compressor seal around the stem of its compression valve.
The expansion crank throw in the Scuderi engine leads the compression crank throw and the spark plug fires on or after top dead center. In the Clerk and the Hybrid Engines, it is the reverse and the spark plug fires before top dead center.
Both the Hybrid Engine and the Scuderi engine have cylinder heads with intake and exhaust valves and an air passageway in place of the intake and exhaust ports in the cylinder walls of the Clerk engine. To manage the flow of air between cylinders the Hybrid Engine relies solely on the cylinder head valves, making the pressure control valve unnecessary.
Ordinarily during the exhaust cycle, exhaust gas is simply pushed by the engine piston out of the engine cylinder. Both valves of the 2 stroke engine of the Hybrid Engine are simultaneously open during part of the exhaust cycle. The same is true in the Clerk engine but not for the Scuderi engine.
Pushed by the pump piston in the Hybrid Engine, the cooler, dense intake air from the pump cylinder displaces the bulk of hot, less dense exhaust gas from the engine cylinder. In this process, some residual exhaust gas remains and gets re-cycled, possibly eliminating the need for an exhaust gas re-circulating valve mentioned in the Background.
Similar to current 4 stroke spark ignition internal combustion engines, the Hybrid Engine uses a fuel injector for fuel delivery during the compression cycle which prevents unburned air/fuel mixture from escaping into the atmosphere.
Novelty Features of the Hybrid Engine The major properties that make the Hybrid Engine unique are:

1. It designates one cylinder as the 2 stroke engine and the second cylinder as a 2 stroke air pump that supplies the engine with a reliable flow of air from the atmosphere for scavenging. But unlike the Clerk and the Scuderi engines, the Hybrid Engine's pump cylinder also works in conjunction with the engine cylinder during part of the intake, part of the compression cycle and part of the exhaust cycle.
2. The Hybrid Engine uses 5 cycles instead of the conventional 4 cycles of internal combustion:
a. The conventional intake cycle is renamed air intake cycle when the pump cylinder admits air from the atmosphere.
b. A new air transfer cycle is inserted between the conventional intake cycle and the compression cycle. This cycle moves intake air from the pump cylinder into the engine cylinder. Fuel is delivered during the air transfer cycle and/or compression cycle.
c. Compression, combustion and exhaust cycles complete the Hybrid Engine's 5 cycles of internal combustion.
3. The Hybrid Engine splits the 5 cycles of internal combustion into smaller stages.
4. The equal arc subdivisions of the 360 degree circumference of crankshaft revolution define the opening and closing of the intake, compression and exhaust valves.
5. The crank throw assignment to the pump piston and engine piston with the pump piston in the lead, it arrives at its dead centers ahead of the engine piston.
6. The compression seal around the stem of the compression valve has not been used in other engines.
7. The volume capacity of the pump cylinder is equal to or greater than the volume capacity of the engine cylinder, 8. The optional compression plate is sandwiched between the engine cylinder head sub-assembly and the engine cylinder block.
The values assigned to the arc and crank throw angle determine the characteristics of the Hybrid Engine.

The above features are expanded upon below.
Cylinder Designation The Hybrid Engine uses the secondary cylinder as an auxiliary air pump device. Like the fans, oil and water pumps the attached or embedded 2 stroke air pump is essential for the successful and continued running of the 2 stroke engine.
Splitting of 360 Degrees into Arcs and Stage of Five Internal Combustion Cycles Conventional internal combustion engines define the down stroke of the piston inside the cylinder to begin at the top dead center (TDC) and ends at the bottom dead center (BDC). The up stroke does the opposite. The timing and duration of the intake, compression, combustion and exhaust cycles directly correlate to the position of the piston being at or very close to TDC
or BDC.
The 5 cycles of the Hybrid Engine's internal combustion is shown in Tables 1, 2 and 3. During the air intake cycle the pump cylinder admits air from the atmosphere. This cycle is divided into early an air intake stage and a final air intake stage. The air transfer cycle is inserted between the air intake cycle and the compression cycle. This new cycle is divided into an early an air transfer stage, a middle air transfer stage and a final air transfer stage when intake air is transferred from the pump cylinder into the engine cylinder. The compression cycle is divided into an early compression stage and a final compression stage. The combustion cycle remains intact as one stage. The exhaust cycle is divided into an early exhaust stage and a final exhaust stage.
Shown in Figures 5, 6 and 7, the Hybrid Engine subdivides the 360 degree rotation of the crank throw into at least 16 equal arcs. The arcs are 0 to 1, to 2, 3 to 4, 4 to 5, 5 to 6, 6 to 7, 7 to 8, 8 to 9, 9 to 10, 10 to 11, 11 to 12, 12 to 13, 13 to 14, 14 to 15 and 15 to 0. Timing and duration of the stages are defined using the arc which the crank throw is pointing at and accordingly the valves are set to open or close positions as required for the execution of a specific stage of the cycle.
Tables 1, 2 and 3, in addition to the cycles and stages, show the pistons' direction, the valves positions and the arcs the crank throws point to at different stages. The following is a detailed description of the Hybrid Engine's operation.
1. Illustrated in Figure 10, the Hybrid Engine assigns the early air intake stage to the pump cylinder (8) and the final compression stage of the compression cycle to the engine cylinder (18). The pump intake valve (2) is open, the engine compression valve (10) is closed and the engine exhaust valve (12) is closed. The pump piston (6) moves down admitting air from the atmosphere and the engine piston (16) moves up compressing the air/fuel mixture in the engine cylinder (18). When the engine piston reaches X degrees before TDC, a spark plug ignites initiating combustion of compressed air/fuel mixture.
2. Illustrated in Figure 11, the Hybrid Engine assigns the combustion cycle to the engine cylinder and the final air intake stage of the intake cycle to the pump cylinder (8). The pump intake valve (2) is open, the engine compression valve (10) is closed and the engine exhaust valve (12) closes. The pump piston (6) moves down and the engine piston (16) moves down. When the pump crank throw (26) reaches arc 8 to 9, the intake valve (2) closes and the pump piston (6) reverses direction and begins to move up.
3. Illustrated in Figure 12, the Hybrid Engine assigns the early exhaust stage to the engine cylinder (18) when the pump intake valve (2) is closed, the engine compression valve (10) closed and the engine crank throw reaches arc 6 to 7. The pressure in the engine cylinder is higher that the atmospheric pressure. The exhaust valve (12) opens and the hot exhaust gas escapes out the exhaust port (13). The engine piston (16) continues moving down and the pump piston (6) continues moving up. With the engine compression valve (10) in a closed position, the pump piston (6) exerts pressure on the intake air in pump cylinder (8).

4. Illustrated in Figure 13, the Hybrid Engine assigns the middle air transfer stage and the middle exhaust stage to both pump cylinder (8) and engine cylinder (18). When the engine crank throw (27) reaches arc 7 to 8, the engine compression valve (10) opens. Due to the higher cylinder (8) pressure, air blows into the engine cylinder (18). The blowing action lowers the temperature inside the engine cylinder (18) and forces more gas out the exhaust port (11). The two cylinders go into the early air transfer and middle exhaust stages. The engine piston (16) continues moving down. After the pump crank throw (26) passes arc 10 to 11, the middle air transfer stage begins. The pump piston (6) continues moving up pushing the intake air from the pump cylinder (8) into the engine cylinder (18). The hot exhaust gas directly below the engine compression valve (10) is displaced. The exhaust gas directly under the exhaust valve (12) is displaced and goes out the engine exhaust port (11).
5. Illustrated in Figure 14, the Hybrid Engine assigns the middle air transfer stage and the final exhaust stage to both pump cylinder (8) and engine cylinder (18). The pump intake valve (2) is closed, the engine compression valve (10) is open and the engine exhaust valve (12) is open. The pump piston (6) moves up, pushing the intake air from the pump cylinder (8) into the engine cylinder (18), displacing the hot exhaust gas directly below the compression valve (10). The engine piston (16) moves up, pushing the hot exhaust gas directly below the exhaust valve (12) out the exhaust port (13).
6. Illustrated in Figure 15, the Hybrid Engine assigns the final air transfer stage and the early compression stage to both the pump cylinder and the engine cylinder. The pump intake valve (2) is closed, the engine compression valve (10) is open and the engine exhaust valve is closed.
The pump piston is moving up and the engine piston is moving up.
Injector (21) delivers the fuel. The two cylinders are coupled and both pistons are compressing the air/fuel mixture.
Five cycles are completed and process goes back to step a.

Cylinder Head Connection Shown in Figures 2, 3 and 4, the Hybrid Engine shows the top dead center (4) of the pump piston (6) in line with the top lip of the air passageway (9) of the engine cylinder head (11) sub-assembly. This makes a shortest air passageway for faster transferral of as much air as possible.
Crank Angle As acknowledged in the Background, the pump crank throw (26) leading the engine crank throw (27) at right angle or 90 degrees was introduced in 1807.
In the Hybrid Engine, the value of the crank throw angle (30) between the crank throws (26 & 27) is that it provides a wider range between 10 and 110 degrees.
Shown in Figures 5, 6 and 7, in the Hybrid Engine the crank throw (26) which is connected to the pump piston (6) leads the crank throw (27) connected to the engine piston (16). Whether the crankshaft (28) is in a clockwise or counterclockwise rotation, the pump piston (6) reaches its top dead center (4) and bottom dead (7) center ahead of the engine piston (16) reaching its top dead center (14) and bottom dead center (17) respectively.
Given that the position of engine crank throw (27) of the engine piston (16) stays the same, Tables 1, 2 and 3 shows that using different values for the crank throw angle (30), the position the pump crank throw (26) points to changes. For example, the combustion cycle of the engine cylinder (19) begins when the engine crank throw (27) of the engine piston (16) is at 0 or 360 degree and ends when the engine crank throw (27) reaches arc 6 to 7.
The engine piston (16) is moving down.
1. With a value of 67.5 degrees for crank angle (30) in Table 1, the pump piston (6) is moving down when the leading pump crank throw (26) is at arcs 3 to 8 and ending at arcs 9 to 10 when the pump piston (6) is moving up.
2. With a value of 45 degrees for crank angle (30) in Table 2, the pump piston (6) is moving down when the leading pump crank throw (26) is at arcs 2 to 8 and ending at arcs 8 to 9 when the pump piston (6) is moving up.
3. With a value of 90 degrees for crank angle (30) in Table 3, the pump piston (6) is moving down when the leading pump crank throw (26) is at arcs 4 to 8 and ending at arcs 11 to 12 when the pump piston (6) is moving up.
Table 4 summarizes the impact of different values, from 45 degrees, 67.5 degrees and 90 degrees, for the crank throw angle (30) on the position of the pump crank throw (26) and the position of the engine crank throw (27) during the early compression and final compression stages. By implication, this also has a direct impact on the final position of the engine piston (16) at the start of the early compression and at the end of the final compression stages. Anyone in the field can deduce that the eventual size of the compression chamber (30), the pre-ignition pressure inside the combustion chamber and the resulting engine's compression ratio will depend on when the exhaust valve closes at the start of the early compression stage.
Compression Integrity Referring to Figure 8, the Hybrid Engine shows the stem of the compression valve (10) fitted with a compression seal (22) to preserve compression integrity and to prevent the air/fuel mixture from leaking out through the clearance space between the stem hole and the compression valve (10) stem in the engine cylinder (11) head.
Referring to Figure 2, 3 & 4, the Hybrid Engine is designed to maximize the air transfer from pump cylinder (8) into the engine cylinder (18).
1. The pump piston's top dead center (4) is made higher than the engine cylinders' top dead center (14), 2. The pump piston at its TDC and the pump engine piston (15) ring below the lower lip of the air passageway (9) of the engine cylinder head (11) sub-assembly ensures that the air/fuel mixture does not leak into the pump crankcase.

Compression Plate Referring to Figure 2, 3 & 4, the Hybrid Engine shows the engine has an optional compression plate (1) sandwiched between the engine cylinder head (11) and the cylinder block (29). Shown in Figures 9 the compression plate (1) has a spark plug hole (5), an optional fuel injection hole (9), a compression valve hole (2) and an exhaust valve hole (6). The valve holes (2 & 5) have inner and outer circumferences (4 &3, 7 & 8) designed to promote swirl of the incoming intake air/fuel mixture and faster outflow of the exhaust gas respectively. In addition the compression plate:
1. serves as the top boundary for the combustion chamber, 2. allows:
a. the compression plate to absorb most of the stresses from high temperature and combustion pressure, b. design options for shape and contour of the compression valve hole (3a) to optimize and promote the swirl of the air inflow into the engine cylinder (18), c. design options for shape and contour of the exhaust valve hole (4a) to maximize the outflow of exhaust gas from the engine cylinder (18), d. some flexibility in manufacturing the pump cylinder head (1) and engine cylinder head (11) as either two separate units or as one single unit.
3. reduces:
a. the stresses from high temperature and combustion pressure on the entire cylinder head assembly, b. weight by using a lighter material for the pump cylinder head (1) and engine cylinder head (11).
4. Lowers the cost of maintenance related to cracked or warped cylinder heads; replacing only the compression plate is cheaper than replacing the complete cylinder head assembly.
Cylinder Volume Referring to Figures 2, 3 & 4, the Hybrid Engine the pump cylinder (8) and the stroke of the pump piston (6) is longer than that of the engine cylinder (18) and the engine piston (16). The pump cylinder volume capacity is greater than the engine cylinder's volume capacity which compensates for the scavenging loss of intake air mass. Although this can also be accomplished through other means, such as larger pump cylinder bores and larger pump piston (not shown), this option is easily implemented in conjunction with the configuration of the air passageway (9).

Summary of the Invention The Hybrid Engine is an unprecedented cross between a single cylinder 2 stroke pump and a single cylinder 2 stroke 4 cycle internal combustion engine. The Hybrid Engine uses 2 strokes of the pump plus the simultaneous 2 strokes of the engine to circulate fresh air through the two cylinders and back to the atmosphere. Using the intake air from the pump, the engine completes the Hybrid Engine's 5 cycles of internal combustion to turn the crankshaft. Since the 2 strokes are happening simultaneously inside 2 cylinders, the Hybrid Engine takes only 2 strokes to turn its crankshaft one complete revolution. The Hybrid Engine is a 2-stroke 5-cycle internal combustion engine. The invention can be classified under either 2-stroke or 4-stroke internal combustion engine.
The Hybrid Engine uses five cycles to produce internal combustion:
1. Additional cycle added to the conventional 4 cycles of internal combustion.
2. Subdivision of the resulting five cycles into stages.
3. The cylinder head design, i.e. the passageway, the compression seal and the compression plate, that allows the stages to be performed in either the pump cylinder and/or the engine cylinder.
The stages of the 5 cycles of internal combustion in the Hybrid Engine are:
1. An air transfer cycle to move intake air from the pump cylinder to the engine cylinder inserted between the conventional intake cycle and the compression cycle and subdivided into an early air transfer stage, a middle air transfer stage and a final air transfer stage.
2. The conventional intake cycle is renamed air intake cycle when the pump cylinder admits air from the atmosphere; fuel is injected either during the air transfer cycle, the compression cycle or both; these stages are early air intake and final air intake.
3. Compression of the air/fuel mixture includes an early compression and a final compression stages.
4. Combustion of the air/fuel mixture takes place only a single stage.

5. The procedure to push smoke and other combustion by-products out of the combustion chamber into the atmosphere is done during an early exhaust stage, a middle exhaust stage and a final exhaust stage.
The Hybrid Engine has the following notable features:
1. Sixteen equal arc subdivisions of the 360 degree circumference, using the arc positions to define the opening and closing of the intake, compression and exhaust valves.
2. The crank throw assignments of the pump piston and engine piston with the pump piston in the lead, arriving at its dead centers ahead of the engine piston; the value of the angle between crank throws, also known as crank throw angle, directly impacts the resulting compression ratio and the behavior of the single cylinder 2 stroke engine. A cost/benefit research and development study on using a gear-shifting mechanism to dynamically change the crank throw angle can be designed.
3. The compression seal around the stem of the compression valve.
4. The optional compression plate sandwiched between the engine cylinder head sub-assembly and the engine cylinder block.
5. During the air transfer and compression cycles, fresh intake air mixes with the exhaust gas inside the engine cylinder. This makes the use of exhaust gas recirculation valve redundant.
6. The larger pump cylinder volume capacity also makes the use of turbocharger unnecessary.
7. A 4 cylinder 2 stroke Hybrid Engine will use 50% less spark plug, 50% less fuel injector, no turbocharger and no exhaust gas recirculation valve compared to a comparable current 4 cylinder 4 stroke engine.
The Hybrid Engine can easily be manufactured for the original equipment manufacturers market using current technologies. This applies also to the parts of the engine, such as cylinder head sub-assembly, the crankshaft, the compression plate and the modified version of engine control unit software module, for conversion and after sales market.

The invention is a hybrid, four-cylinder, 2-stroke, 5-cycle engine that turns the crankshaft two times faster than a comparable conventional four-cylinder, 4 stroke, 4-cycle engine does.

Pump Piston (6) Engine Piston (16) Exhaust Engine Shared Intake Compressio Cycle Stage Valve Drawing ? Valve (2) Piston Crank Throw Piston Crank Throw n Valve (10) (12) Direction _ Position Direction Position Air Intake, Early Figure 10 0 to 3 Up 13 to 0 .
Compression Final Open Down Close Air Intake Final 3 to 8 Close Figure 11 No 0 to Combustion 8 to 9 Exhaust Down Figure 12 Early 9 to 10 6 to Air Transfer Exhaust 7 to 8 Figure 13 Open Air Transfer Middle Close Up 10 to 12 8 to Air Transfer 9 to 10 Open Figure 14 Yes Exhaust Final 12 to 14 UP 10 to 11 o Air Transfer Final i..) Figure 15 14 to 0 11 to 13 Close co Compression Early ko i..) Table 1¨ Stages, Piston Directions and Valve Controls Using 67.5 Degrees Crank Throw Angle (xi u.) i..) o Pump Piston (6) Engine Piston (16) 1-, Exhaust cn Engine Shared Intake Compression O
Cycle Stage Valve .o.
Drawing ? Valve (2) Piston Crank Throw Piston Crank Throw Valve (10) 1 (12) i..) Direction Position Direction Position Early &
Air Intake Figure 10 Final 0 to 2 Up 14-0 Open Down Close Compression Final No Close Figure 11 Combustion 2 to 8 0 to Exhaust Figure 12 Early 8 to 9 Down 6 to Air Transfer Exhaust 7 to 8 Figure 13 Open Air transfer Middle 9 to 12 8 to 9 close Up Air Transfer 9 to 10 Open Figure 14 _____________ Yes Exhaust Final 12 to 13 Up 10 to 11 Air Transfer Final Figure 15 13 to 0 11 to 14 Close Compression Early Table 2 ¨ Stages, Piston Directions and Valve Controls Using 45 Degrees Crank Throw Angle 3.

Pump Piston (6) Engine Piston (16) Exhaust Engine Shared Intake Compression Cycle Stage Valve Drawing ? Valve (2) Piston Crank Throw Piston Crank Throw Valve (10) (12) Direction Position Direction Position _ Air Intake Early Figure 10 0 to 4 Up Compression Final Open Down Close Air Intake Final 4 to 8 Close Figure 11 No 0 to 6 Combustion 8 to 10 Exhaust Figure 12 Early Air Transfer Down to 11 6 to 7 Exhaust Figure 13 Open o Air Transfer Middle Close Up o Air Transfer 11 to 12 7 to 8 Open n.) co Figure 14 Yes Exhaust Final 12 to 15 8 toll ko _ n.) cri Air Transfer, Final Up w Figure 15 15 to 0 11 to 12 Close Compression Early n.) I
o 1-, Table 3 ¨ Stages, Piston Directions and Valve Controls Using 90 Degrees Crank Throw Angle 0, O
Ø
i iv 1-, Pump Piston (7) Engine Piston (17) Exhaust Angle in Compression Shared Intake Compression Drawing Valve Degrees Stage ? Valve (2) Piston Crank Throw Piston Crank Throw Valve (10) Direction Position Direction Position (12) Early Yes Up 13 to 0 Up , 11 to 14 Open Close Figure 3 45 Close Final No 14 to 0 Close , Close Early Yes Up 14 to 0 Up 11 to 13 Open . Close Figure 2 67.5 Close Final No 13 to 0 Close Close Early Yes Up 15 to 0 Up 11 to 12 Open Close Figure 4 90 Close Final No 12 to 0 Close Close Table 4¨ Effect of Different Crank Throw Angles on Compression Stages Timing

Claims

Hybrid Split Cycle lnternai Combustion Engine I claim:

1. The unique design, function and use of the compression valve (10) in Hybrid Split Cycle Internal Combustion Engine shown in Figure 8, having a tapered valve head thick enough to cover the passageway (9) completely sealing the pump cylinder (8) and the power cylinder (18) from each other during the simultaneous pump intake and combustion cycles.