GB2235014A - I.c engine cylinder - Google Patents

Abstract

A sleeve 22 arranged to surround the cylinder 10 is provided with at least one port or slot 24 which is operative, when the sleeve 22 is rotated about the cylinder 10, to open and close cylinder inlet and exhaust ports. The rotation is caused by a toothed wheel 26 driven by the engine's crankshaft. Wheels 26 of adjacent cylinder sleeves 22 may engage. Two contra rotating sleeves may control the ports. The sleeve 10 may be formed of a spring steel strip with interleaved crenellated edges. <IMAGE>

Description

SLEEVE VALVE This invention relates to a sleeve valve especially a sleeve valve for an internal combustion engine, for example, a two or four stroke engine.

Engines including sleeve valves have been known and in use for some time and possess certain advantages over known poppet valve engines. In general a sleeve valve engine includes one or two liners which can slide up and down (and may also rotate) relative to the piston. Ports cut in the upper portions of the liner or liners are arranged to open and close the inlet and exhaust passages to the cylinder at the correct intervals. Advantages of the sleeve valve engine over poppet valve engines are its quietness of operation, its simplicity of construction and a higher efficiency.

Although a sleeve valve engine possesses these advantages there are also certain disadvantages caused by its method of operation. Because the motion of the liner is reciprocal, this being true both of its up and down motion and any rotation, a certain amount of stress is produced. Furthermore, where a high engine speed is required the motion of the liners with respect to the cylinder is also required to be extremely fast which can cause mechanical problems and excess wearing due to the relatively large area of sleeve surface which is required to be lubricated with respect to the stationary cylinder. Furthermore, the maximum speed at which a sleeve valve engine may operate is limited by the inertia of the sleeve and its effect on the reciprocal motion thereof.

It is an object of the present invention to provide a sleeve valve for an engine which overruns some or all of these disadvantages.

With this object in view the invention provides a sleeve valve for an engine in which a sleeve is rotated fully about a piston's cylinder thus providing the opening and closing of inlet and exhaust ports in the cylinder's wall.

It will be seen that such an arrangement provides for the opening of inlet and exhaust ports without the use of reciprocal motion thus greatly reducing stresses and avoiding problems caused by inertia of the valve parts.

In a preferred aspect of the invention there is provided a sleeve valve for engine comprising a sleeve configured to at least partially enclose a piston cylinder, said sleeve being provided with a first port, the sleeve being rotatably arranged around the cylinder such that the first port communicates in one position with an inlet port and in a secured positon with an exhaust port both provided in the cylinder's wall, the valve also including drive means connected to the sleeve and operable to rotate the sleeve about the cylinder such that the inlet and outlet ports are sequentially opened and closed to permit combustion gases to enter and leave, respectively the piston's cylinder.

Where high speed opening and closing of inlet and exhaust ports is required a preferable modification of the invention provides two contra rotating sleeves arranged about the piston's cylinder. In this way the actual speed with which the ports are opened and closed is greatly increased thus allowing for an increased engine speed as would be required in, for example, racing car engines.

Preferably the drive means for the sleeve is provided by a connection to the crank shaft with a suitable gearing arrangement so that the sleeve rotates at the appropriate speed to open and close the inlet and exhaust ports in their correct sequence and at the required time intervals.

Preferably the cylinders and their associated sleeves are arranged at close intervals such that by providing teeth on the exterior surface of the sleeve one sleeve can connect with and rotate the adjacent sleeve. In this way it is only necessary to provide the original drive to one such sleeve with all other sleeves in the engine being driven in correspondence therewith.

In a further modification of the invention several ports are provided per sleeve which will thus be operative to open and close the exhaust and inlet ports of the piston cylinder several times during one rotation of the sleeve thereabout. In this way it is possible to obtain a rapid cycling of the engine whilst only requiring a relatively slow rotation of the sleeve about the piston cylinder.

The sleeve itself is conveniently formed of a cylinder of metal fitting around the cylinder sleeve.

However, a strip of spring steel may also be used, compressed on to the cylinder's wall, to provide the required sieeve-like configuration.

The invention will be described further by way of example, with reference to the accompanying drawing in which the single figure is a cross-sectional side elevation through a preferred embodiment of a sleeve valve engine according to the invention.

In the single figure a cylinder 10 encloses a piston 12 of, for example, an internal combustion engine (not shown). One end of the cylinder 10 is seated in a cylinder head 14. A sealing ring 16 around the piston 12 provides an air tight seal with the cylinder wall.

It will be understood that the arrangement has been simplified for clarity and in a conventional combustion engine at least a spark plug would be provided to cause ignition of the combustion gas mixture in a combustion space 18 between the piston 12 and the cylinder head 14.

Additionally the piston 12 would be attached to a crank shaft such that its recriprocal motion within the cylinder 10 causes rotational movement of the crank and hence the required movement of the drive wheels etc.

In order to admit the required combustion gas mixture into the combustion space 18 an inlet port 20 is provided in the cylinder 10. Conventionally at least an exhaust port (not shown) is also provided to remove waste gases after combustion. In the figure the exhaust port is not shown as it is sited at approximately 1200 about the cylinder's periphery from the inlet port 20.

It is also known to provide a third port as an exhaust purge, however, such is not present in the preferred embodiment.

It will be appreciated from the drawing that the inlet port 20 only communicates with the combustion chamber 18 when the piston is moved relatively downwardly from the position indicated in the figure during its "suction stroke". Whilst the inlet port 20 is uncovered combustion gases are admitted to the combustion chamber 18 which are then compressed by the upward movement of the piston 12. In the position indicated in the drawing the piston 12 is covering the inlet port thus preventing admission of further combustion gases to the combustion chamber 18.

In order to effect the closing of the inlet port and opening of the exhaust port (not shown) in proper sequence to effect the admission and removal of combustion gases to the combustion chamber 18 a sleeve 22 is provided around the cylinder 10. The sleeve 22 is provided with at least one port or slot 24 therein which corresponds to the inlet port 20 and exhaust port provided in the cylinder 10. The sleeve 22 is arranged so as to be rotatable around the periphery of the cylinder wall 10 thus the slot 24 is operative to open and close the inlet port 20 and exhaust port in sequence depending on the speed of rotation of the sleeve 22 about the cylinder 10.A toothed wheel 26 is provided at one end of the sleeve 22 engageable with drive means (not shown) to effect rotation of the sleeve 22 and also with the similarly toothed wheel of an adjacent sleeve so as to transfer the rotational movement of the sleeve indicated along a succession of adjacently placed cylinder and sleeve assemblies.

It will be understood that with the sleeve valve assembly illustrated there is no reciprocal motion of the sleeve and hence stresses formed through such motion and also any inherent resistance to movement caused by inertia of the sleeve is thereby overcome. Furthermore the maximum engine speed which can be obtained by an engine with such a sleeve valve is increased over that heretofore known by virture of these advantages.

In a modified embodiment of the invention two concentric sleeves are provided each having ports or slots provided therein for communication with the inlet and exhaust port provided in the cylinder wall. These two sleeves are designed to contra rotate and are arranged such that there respective slots are on a common axis and co-operate with each other to open and close the inlet and exhaust port in the cylinder. By providing such contra rotating sleeves the actual time period during which the inlet and exhaust ports are respectively opened can be reduced thus obtaining faster opening of these ports whilst still maintaining a relatively slow rotational speed of the sleeves themselves. Thus where an extremely high engine speed is required, for example, in a racing car engine, this arrangement provides advantages over any heretofore known engine valve arrangement.The sleeve itself can be provided in any convenient form, for example, a cylindrical sleeve of metal or can be provided as a strip of sprung steel which is compressed about the cylinder wall into a sleeve-like configuration.

Preferably the edges of the strip are crenellated so as to interleave and form the necessary sleeve-like formation. Other methods of forming a sleeve may also be possible.

Although the preferred embodiment is described having only one slot 24 in the sleeve 22 two or more slots may be provided as required according to engine operating characteristics and relative time periods for opening and shutting the inlet and exhaust ports of the piston cylinder. Where the engine is of a Vconfiguration two cylinder sets would be provided at approximately 600 to each other thus the first cylinder in each set would be attached to drive means which may be separately or collectively driven by the crank shaft.

Claims (8)

1. A sleeve valve for an engine in which a sleeve is rotated fully about a piston's cylinder thus providing the opening and closing of inlet and exhaust ports in the cylinder's wall.

2. A sleeve valve as claimed in claim 1 comprising a sleeve configured to at least partially enclose a piston cylinder, said sleeve being provided with a first port, the sleeve bring rotatably arranged around the cylinder such that the first port communicates in one position with an inlet port and in a secured position with an exhaust port both provided in the cylinder's wall, the valve also including drive means connected to the sleeve and operable to rotate the sleeve about the cylinder such that the inlet and outlet ports are sequentially opened and closed to permit combustion gases to enter and leave respectively the piston's cylinder.

3. A sleeve valve as claimed in claim 1 or claim 2 in which two contra rotating sleeves are provided arranged about the piston's cylinder.

4. A sleeve valve as claimed in any preceding claim in which the drive means for the sleeve is provided by a connection to the crank shaft with a suitable gearing arrangement so that the sleeve rotates at the appropriate speed to open and close the inlet and exhaust ports in their correct sequence and at the required time intervals.

5. A sleeve valve as claimed in any preceding claim in which the cylinders and their associated sleeves are arranged at a relatively close spacing and teeth are provided on the exterior surface of the sleeves thereby permitting one sleeve to connect with and rotate the adjacent sleeve.

6. A sleeve valve as claimed in any preceding claim in which several ports are provided for each sleeve which will thus be operative to open and close the exahust and inlet ports of the piston cylinder several times during one rotation of the sleeve thereabout.

7. A sleeve valve as claimed in any preceding claim in which the sleeve itself is formed of a strip of spring steel compressed on to the cylinder's wall so as to provide the required sleeve-like configuration.

8. A sleeve valve for an engine substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.