WO2015015508A2

WO2015015508A2 - Fixed piston, moving cylinder 2 stroke i c engine. with super charging annular chamber

Info

Publication number: WO2015015508A2
Application number: PCT/IN2014/000454
Authority: WO
Inventors: R. Rajan K.
Original assignee: K R Rajan
Priority date: 2013-08-02
Filing date: 2014-07-07
Publication date: 2015-02-05
Also published as: WO2015015508A3

Abstract

An innovative design of 2 stroke internal combustion engine (IC Engine) is disclosed which will obviate the draw backs of conventional 2 stroke engines, by having reduced polluting emission & increased fuel efficiency, configured as shown in the concept sketch, cut away view; (Fig.2).The enclosed drawing (Fig.1) illustrates the structure of the engine, with moving cylinder (4), fixed piston (5), sliding sleeve ports (6, 7), annular air compression chamber (14) and fuel injector (15). The engine can be made in Gasoline or Diesel versions and can be used in Automobiles or stationary machines to get high power to weight ratio, smooth torque, quick acceleration, high fuel efficiency & reduced consumption of lubrication oil. Materials & construction can be similar to that of conventional engines, but design as per the new concept.

Description

COMPLETE SPECIFICATION

TITLE OF INVENTION:

FIXED PISTON, MOVING CYLINDER 2 STROKE I C ENGINE WITH

SUPERCHARGING ANNULAR CHAMBER.

TECHNICAL FIELD & BACKGROUND OF INVENTION

Internal combustion engines (IC engines) are used as prime mover in

automobiles and stationary machines. IC engines are classified into 2 types, 2 stroke and 4 stroke engines. 2 stroke engines complete the cycle in 2 strokes; that is one power stroke per one revolution of the crank shaft.

The 2 stroke engines have following advantages:

(a) Higher power to weight ratio

(b) Smoother torque distribution

(c) Quicker acceleration.

(d) Simpler mechanism with less maintenance

However, 2 stroke engines suffer from following serious disadvantages:

(a) Higher emission of pollutants

(b) Poor fuel efficiency,

(c) Higher consumption of lube oil

Due to these reasons, 2 stroke engines are loosing acceptability in Motor cycles and 3 wheelers as well as in small cars. A new design to obviate these problems is conceived.

Prior art: Present 2 stroke engines, (excluding valve types) have fixed ports on opposite sides of the cylinder wall. Opening & closing of ports are taking place by the uncovering & covering actions of piston, during up & down movement. The exhaust port is placed slightly above the inlet port and hence during the downward movement of piston, exhaust port opens first. Immediately after that inlet port opens, letting in fresh charge of air-fuel mixture. Exhaust port remains open while the fresh charge is flowing inside causing scavenging of combustion products. There are limitations in this design. Scavenging is not perfect. Also, a part of fresh charge escapes through exhaust port.

The fresh air-fuel mixture is compressed in the crank case for transferring into the cylinder. The crank case compression ratio is poor as volume of crank case is large compared to swept volume of piston. More over, due to the passage of fuel-air mixture through crank case, splash oil lubrication of cylinder is not possible. Hence, lube oil is added in the fuel-air mixture and this lube oil burns during combustion.

Drawbacks of prior art

(1) High level of polluting emissions: The location of inlet & outlet ports is such that scavenging is not proper and a part of fresh charge escapes through exhaust port causing poor emission. Also, the lubricant added with fuel, burns during combustion causing emission of smoke. (2) Poor fuel efficiency. Scavenging is not proper causing loss of some fuel through exhaust port.

(3) Higher consumption of lubricating oil: Crank case lubrication is not possible, since inlet air is drawn through crank case. Hence, lube oil is added in the fuel-air mixture and this lube oil burns during combustion, causing increased

consumption of lube oil.

New design:

In the new design, the piston is fixed and cylinder is moving. The cylinder moves inside a sleeve. The reciprocating cylinder & stationary outer sleeve on the engine block both have ports, located at top and bottom portions. Inlet port is at top and exhaust port is at bottom. Opening and closing of ports take place when ports in cylinder and sleeve coincide during the reciprocating motion of cylinder. Ports can be made all around for faster entry of air and sudden discharge of exhaust. Fresh air flow is from top to bottom creating unidirectional scavenging. Very efficient scavenging can be expected.

Inlet air does not contain fuel. Fuel is injected at high pressure into fresh air, after closing of exhaust ports. Hence, there is no chance of fuel escaping.

For achieving supercharging, the inlet air is compressed inside an annular chamber. Top part of the reciprocating cylinder is shaped to work as an annular piston to compress inlet air. The compression should be more than the crank case compression of common 2 stroke engines. Hence high pressure super charging of inlet air and better scavenging can be achieved.

In the new design, crank case is not used as an air compression chamber. Crank case can contain lubrication oil similar to that of 4 stroke engines. Hence lubrication oil will not be burned or excessively consumed.

Construction:

Crank case & other parts of the engine block can be made as in the prior art using Cast iron or Aluminium alloy. Crank parts can be made by forged steel, as in the prior art. Fixed piston, moving cylinder and air compression chamber can be made using Aluminium alloys. All other pars such as fuel injector, spark plug, connecting rod, rings, cylinder sleeve etc can be made as in prior art. Reed valves & other parts required for this new engine will have to be made through detailed R&D work.

Advantages of the new 2 stroke IC engine design:

■ Efficient scavenging leading to least pollution.

■ Fuel injection & the new port design will give better fuel efficiency.

■ Lube oil is not mixed with inlet air & hence no oil smoke.

■ Splash lubrication possible; hence low lube oil consumption.

■ Adaptable for both Diesel & Gasoline engines with fuel injection. DESCRIPTION

CONSTRUCTION

The fundamental difference from the prior art is that the new design has a piston which is fixed (not moving as in conventional engines). The cylinder reciprocates moving over the fixed piston. The moving cylinder is connected to crank shaft through connecting rode as can be seen in the enclosed drawing (Fig.1).

Combustion chamber is the space between the fixed piston & the hollow part of moving cylinder.

At the top part of the engine, there is an annular chamber for compressing the inlet air, to achieve super charging. The top part of the moving cylinder is shaped to form an annular piston moving inside the annular air chamber. There is inlet reed valve for air inlet to air compression chamber. Reed valve is provided on the annular air piston for air to cross from top to bottom part of the chamber.

Compressed air passes to combustion chamber through inlet port.

Inlet & exhaust ports are formed through holes in the cylinder wall and engine wall. Inlet port is at the top & exhaust port is at the bottom.

Fuel injector & spark plug are positioned on the fixed piston. Fuel is charged through electronically controlled high pressure direct injectors.

Construction:

Crank case & other parts of the engine block can be made as in the prior art using Cast iron or Aluminium alloy. Crank parts can be made by forged steel, as in the prior art. Fixed piston, moving cylinder and air compression chamber can be made using Aluminium alloys. All other pars such as fuel injector, Electronic control unit, spark plug, connecting rod, rings, cylinder sleeve etc can be made as in prior art. Reed valves & other parts required for this new engine will have to be made through detailed R&D work

With reference to various items in the drawing (Fig.1), descriptions are given below:

1. Engine casing is similar to the prior art, except top part.

2. Crank, similar to prior art.

3. Connecting rod, similar to prior art; but connected to moving cylinder.

4. Cylinder, moving over the fixed piston.

5. Fixed piston- holding fuel injector & spark plug.

6. Inlet air port.

7. Exhaust port

8. Reed valve-air inlet to the air compression chamber

9. Reed valve-for air crossing on the annular air piston.

10. Engine wall rings (bottom)

11. Engine wall rings (top)

12. Piston rings-on the fixed piston.

13. Annular air piston rings.

14. Annular air compression chamber at the top part of engine uel injector

park plug-similar to prior art uence of operation

When the moving cylinder travels from BDC to TDC, the top part of the moving cylinder, which is shaped as the annular piston, also moves up. The air at the top part of air chamber crosses to bottom part of the air chamber through reed valves on annular piston.

During the same movement of cylinder from BDC to TDC, inlet port closes first and then exhaust port also closes. After closing of exhaust port, fuel is injected to the fresh air available inside the combustion chamber. Air-fuel mixture gets compressed. At the end of upward stroke, spark plug ignites the charge and combustion takes place.

After combustion, the cylinder moves down from TDC to BDC, exhaust port opens first & combustion products flow out. Next, inlet port also opens, letting high pressure fresh air into the cylinder from air

compression chamber through inlet port at top end, while exhaust port is still open at the bottom. So scavenging of combustion products takes place from top end to bottom in unidirectional manner.

In the next cycle, cylinder starts moving from BDC to TDC and the cycle continues.

Claims

CLAIMS TITLE OF INVENTION FIXED PISTON, MOVING CYLINDER 2 STROKE I C ENGINE WITH SUPERCHARGING ANNULAR CHAMBER. CLAIMS

1. I claim the design of a fixed piston & a cylinder moving over the piston in two stroke internal combustion engines.

2. I claim the design of an annular piston made as an integral part of the moving cylinder, which reciprocates inside an annular chamber to work as a super charging air compressor for any type of IC engines.

3. 1 claim the design of a unidirectional scavenging inlet & exhaust port arrangement by providing holes in moving cylinder wall and engine block wall of a 2 stroke IC engine.

4. 1 claim the design of crank case splash oil lubrication in 2 stroke IC engines by providing separate air charging annular integral compression chamber.

5. 1 claim the design of providing fuel injector & spark plug on the fixed piston in modified 2 stroke IC engine.

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