GB2197024A

GB2197024A - Crankcase compression four-stroke engine

Info

Publication number: GB2197024A
Application number: GB08626260A
Authority: GB
Inventors: Patrick Frederick Fry
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-11-03
Filing date: 1986-11-03
Publication date: 1988-05-11
Also published as: GB8626260D0

Abstract

Air or mixture enters a sealed crankcase 4 through a one way valve mechanism 5 and as the pistons 1 and 2 move down, the volume of the crankcase 4 is reduced and thus the pressure increased. This pressurised air or mixture is fed via ducts 13 to the cylinder which is on its induction stroke. The engine's characteristics may be varied by adjusting the crankcase pressure increase. This can be controlled by connecting separate chambers (10, Fig. 3) the crankcase 4 with valve mechanisms (11) or using a piston (12) in a bore off the crankcase which can be moved in and out to adjust the volume of the crankcase. The charge in the crankcase may be cooled by spraying water into the crankcase or the charge transfer ducts 13 or a heat exchanger may cool the charge. The engine may additionally have a supercharger. <IMAGE>

Description

SPECIFICATION Crankcase raised atmospheric pressure engine The present invention relates to an internal combustion engine working on the four stroke principle which has two or more cylinders.

The power output of this form of engine depends on the amount of fuel-air mixture entering the combustion chambers. So if, for a fixed size combustion chamber, the amount of air, and therefore oxygen, is increased the output power possible is also increased.

The present invention attempts to increase the pressure of the inlet air and in so doing increase the amount of oxygen per unit volume of inlet air.

In accordance with one aspect of the present invention there is provided an internal combustion engine working on the four stroke principle having a plurality of cylinders, each associated with a combustion chamber and a respective piston, said plurality of cylinders being connected to a sealed crankcase area provided with air inlet means, in which the action of one of said plurality of pistons, during its ignition stroke of the four stroke cycle, works to pressurise a volume of air in said sealed crankcase area and this pressurised air is fed to the combustion chamber associated with another piston.

There is also provided a method of increasing the pressure of air entering the combustion chamber of an engine working on the four stroke principle in which two or more cylinders are provided, each associated with a respective combustion chamber and a respective piston, comprising the steps of; (a) Using the ignition stroke of one piston to compress the air in a sealed crankcase area connected to the cylinders; and (b) Opening a cylinder inlet valve, housed on a combustion chamber associated with a second piston, in order to feed the compressed air in the crankcase area to that combustion chamber.

All aspects of the present invention may be applied to an engine with two or more cylinders with either, all cylinders connected to one crankcase area or, groups of two or more cylinders connected to separate crankcase areas.

By way of example only a two cylinder engine version using the present invention will be described with reference to the accompanying drawings in which: Figure 1 shows the basic form of a two cylinder version according to the present invention; Figure 2 shows an engine with pistons moving towards the bottom of their travel; Figure 3 shows a close up view of the crankcase region.

A preferred embodiment of the present invention as shown in Fig. 1 consists of two pistons 1 and 2 operating a crankshaft (or crankshafts, not shown) 3 where both pistons are near the top of of their travel simultaneously. The area beneath the pistons, the crankcase 4, forms a sealed chamber into which air is allowed to enter via a one way valve mechanism 5.

The four stroke combustion principle utilised in the present invention, has two complete revolutions of the engine for every ignition stroke, the order of the cycle being: ignition-the piston moves down, exhaust as the piston moves back up, induction as the piston moves down for the second time and then compression as the piston moves up for the second time. The cycle then repeats itself. In the present invention one piston is on its induction stroke while the other is on its ignition stroke.

The cycle of events depicted in Figs. 1 and 2 is as follows: Starting with both pistons near the top of their travel combustion chamber 9b is filled.

with a fuel-air mixture undergoing compression.

The cylinder inlet valve mechanism 6 to cylinder 8a then opens at approximately the top of piston 1's stroke. The ignition of the fuelair mixture in chamber 9b near the top of piston 2's travel causes the crankshaft (or crankshafts) 3 to rotate.

As both pistons 1 and 2 move downwardly the volume of the crankcase 4 is reduced. Air is prevented from exiting the crankcase via the air inlet by a one way valve mechanism 5 and thus the pressure increases and is distributed between the crankcase 4 and combustion chamber 8b via the feedlines 13. Maximum pressure is reached when piston 2 reaches the bottom of its stroke and approximately at this time the cylinder inlet valve mechanism 6 to combustion chamber 8b closes.

How the pressure increase is achieved can be seen by taking the volume of the crankcase and feedlines at the top of the pistons travel and letting this equal "X", then with the pistons at the bottom of their travel the volume "X' has approximtely been reduced by the cubic capacity of two cylinders.

However as only one cylinder has been connected to the crankcase by a cylinder inlet valve mechanism, the volume of the crankcase and connected elements has been reduced by the cubic capacity of one cylinder. Furthermore, the smaller the crankcase and feedline volume is at the bottom of the piston's travel, compared to the cylinder volume, the higher the pressure increase will be.

As the crankshaft (or crankshafts) 3 continues rotating and the pistons start moving upwardly, combustion chamber 8b undergoes the compression stroke and combustion chamber 9b undergoes the exhaust stroke.

As the pistons move upwardly in each cylin der the pressure in the crankcase 4 is reduced and air is allowed to enter through a one way valve mechanism 5 returning the air in the crankcase to that of the atmospheric pressure outside the engine.

Approximately at the top of piston 2's stroke the cylinder inlet valve mechanism 7 to combustion chamber 9b opens connecting it to the crankcase 4. Fuel-air mixture in combustion chamber 8b is ignited causing the crankshaft (or crankshafts) 3 to rotate.

The process described so far now repeats itself, except with combustion chamber 9b undergoing its induction stroke and combustion chamber 8b undergoing its ignition stroke. The pRQssurQ oi air entering combustion chamber 9b is raised, cylinder inlet valve mechanism 7 to chamber 9b then closes approximately at the bottom of the stroke of piston 1 and then as the pistons move up, combustion chamber 8b undergoes its exhaust stroke and combustion chamber 9b undergoes its compression stroke.

The whole cycle then repeats itself.

In the above described and other embodiments of the present invention fuel may be introduced into the air inside the engine by the following methods: (i) Introducing fuel into the air stream entering the crankcase 4 either before or after the one way valve mechanism 5.

(ii) Introducing fuel into the feedlines 13 from the crankcase to the combustion chambers 8b and 9b.

(iii) Injecting fuel directly into the combustion chambers.

In other embodiments of the present invention the amount of increase in the atmospheric pressure may be varied to alter the engine performance by adjusting the volume of the crankcase. Two methods of accomplishing this whilst the engine is running are: (i) Connecting separate chambers of varying volumes 10 (Fig. 3) onto the crankcase 4 using valve mechanism 11.

(ii) Having a piston 12 in a bore running off the crankcase which can be moved in and out to vary the crankcase volume.

The increase in pressure of the air inside the engine may also give rise to an increase in temperature of this air. In other embodiments of the present invention a cooling means may be provided to reduce the temperature of the air that will enter the combustion chambers.

This may take the form for example, of an air to air heat exchanger, an air to liquid heat exchanger or water injection into the feedlines from the crankcase to the combustion chambers, or water injection into the crankcase.

In the various forms of embodiment of the present invention spark ignition or compression ignition systems may be used to ignite the fuel-air mixture in the combustion chambers.

The present invention may also be used in conjunction with a turbocharger or superchar ger to further raise the pressure of the air that would enter the combustion chambers.

Claims

1. An internal combustion engine working on the four stroke principle having a plurality of cylinders, each associated with a combustion chamber and a respective piston, said plurality of cylinders being connected to a sealed crankcase area provided with air inlet means, in which the action of one of said plurality of pistons, during its ignition stroke of the four stroke cycle, works to pressurise a volume of air in said sealed crankcase area and this pressurised air is fed to the combustion chamber associated with another piston.

2. An internal combustion engine according to claim 1, in which feedlines connect said crankcase area to each of said combustion chambers to provide a path for said pressurised air and said feedlines are provided with cylinder inlet valve mechanisms.

3. An engine according to claim 1 or 2, wherein groups of two or more cylinders are connected to separate crankcase areas.

4. An engine according to claim 1, 2 or 3, having chambers connected to one or more crankcase area via valve mechanisms, thus enabling the volume of said one or more crankcase areas to be altered.

5. An engine according to claim 1, 2 or 3, having a control piston in a bore connected to said one or more crankcase areas which can be moved in and out to enable the volume of said one or more crankcase areas to be altered.

6. An engine according to claim 1, 2, 3, 4 or 5, having a cooling means to reduce the temperature of the air that will enter into said combustion chambers.

7. An engine according to claim 1, 2, 3, 4, 5 or 6, in which fuel is introduced into the air inside the engine by: (i) Introducing fuel into the air entering said one or more crankcase areas either before or after said air inlet means; or (ii) Introducing fuel into the feedlines from said one or more crankcase areas to said combustion chambers; or (iii) Injecting fuel directly into said combustion chambers.

8. An engine according to claim 1, 2, 3, 4, 5, 6 or 7, using either the spark ignition or the compression ignition process.

9. An engine according to claim 1, 2, 3, 4, 5, 6, 7 or 8, which is used to give an additional increase in the pressure of air entering the combustion chambers on a turbocharged or supercharged engine.

10. A method of increasing the pressure of air entering a combustion chamber of an engine working on the four stroke principle in which two or more engine cylinders are provided, each associated with a respective com bustion chamber and a respective piston, comprising the steps of: (a) Using the ignition stroke of one piston to compress the air in a sealed crankcase area connected to the cylinders; and (b) Opening a cylinder inlet valve, housed on a combustion chamber associated with a second piston, in order to feed the compressed air in the crankcase area to that combustion chamber.

11. An engine arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.