GB1560430A

GB1560430A - Internal combustion engines

Info

Publication number: GB1560430A
Application number: GB30821/77A
Authority: GB
Original assignee: Automobiles Citroen SA
Current assignee: Automobiles Citroen SA
Priority date: 1976-07-28
Filing date: 1977-07-22
Publication date: 1980-02-06
Also published as: DE7720734U1; FR2359971B1; ES459600A1; FR2359971A1

Description

(54) IMPROVEMENTS IN OR RELATING TO INTERNAL COMBUSTION ENGINES r t (71) We, SOCIETE ANONYME AUTO MOBILES CITROEN, a French Body Corporate, of 117-167, Quai André Citroën 75747 Paris Cedex 15, France, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to internal combustion engines.

According to the invention, there is pro vided an internal combustion engine comprising a cylinder head having a substan tially hemispherical combustion chamber, said head being provided with two valves disposed with their axes in a plane of sym metry of the combustion chamber, and means for mounting a sparking plug laterally of the plane of symmetry, and a piston whose head, at top dead centre, has a portion corresponding to the shape of the combustion chamber in the zone of one of the valves, and facing the other valve, a concave portion symmetrical relative to the said plane of symmetry.

Further according to the invention, there is provided an internal combustion engine comprising a cylinder head, said head having a substantially hemispherical comb us- tion chamber, two valves disposed with their axes in a plane of symmetry of the combustion chamber, and means for mounting a sparking plug laterally of the plane of symmetry, and a piston having a head which.

when the piston is at top dead centre, has a portion in the zone of one of the valves with a shape corresponding to the shape of the combustion chamber in the zone of that valve, and a concave portion facing the other valve and occupying a major portion of the combustion chamber, said concave portion being symmetrical about the plane of symmetry.

This concave portion constitutes a recess which occupies the major part of the combustion chamber, when the piston is at top dead centre, in such a manner that the combustion chamber is concentrated in the zone of the said other valve.

When the piston is mounted in the cylinder in such a way that its recess faces the exhaust valve, the petrol consumption of the engine is low, whereas when it is mounted in such a manner that its recess faces the inlet valve, the proportion of pollutants formed is low.

The sparking plug is preferably situated with its axis substantially in a plane perpendicular to the plane in which the valves are situated. The position of this plug relative to the recess is thus practically the same, in either direction of mounting of the piston.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings, in which: Figure 1 is an axial cross-section of the cylinder head, cylinder and piston of an engine in accordance with the invention; Figure 2 is a plan view of the piston; and Figure 3 is a perspective view of the piston.

As shown in the drawing, the engine comprises a cylinder head 1 having a substantially hemispherical combustion chamber.

Two valves 2 and 3 are mounted in the head 1 with their axes disposed in a diametrical plane x-x of symmetry of the combustion chamber, the valves 2 and 3 being symmetrical relative to the axis of associated cylinder 4 in which a piston 5 is mounted. The position of a sparking plug is indicated by a line 6 which represents the axis of the plug, the plug being disposed with its axis 6 offset laterally with respect to the cylinder axis substantially in a plane perpendicular to the plane x-x in which the axes of the valves 2, 3 are situated.

As will be seen more particularly in Figure 3, the head of the piston 5 has a valve 2 and is spaced therefrom by a very flat portion 7 which faces towards the valve 2 and is spaced therefrom by a very small gap when the piston 5 is at top dead centre; this flat portion corresponds to the flat por tion of the combustion chamber defined by the head of the valve 2. The flat portion 7 is bounded by two part-spherical portions 8 and 9 conforming to the outline of the cylinder head 1. The flat portion 7 and the two part-spherical portions 8 and 9 which bound it are connected by a rounded edge 10 to concave recess 11, the whole, including the recess, being symmetrical about the plane x-x.

The valve 2 may be the inlet valve, the valve 3 being the exhaust valve. In this case, the engine has a particularly low petrol consumption.

Alternatively, the recess 11 may face the inlet valve. In this case, the petrol consumption is slightly increased, but the proportion of pollutants formed will be very small.

From the foregoing, it will be apparent that the engine can be adapted to provide low fuel consumption, or low pollutant emission, simply by reversing the mounting of the piston in the cylinder.

WHAT WE CLAIM IS:- 1. An internal combustion engine comprising a cylinder head having a substantially hemispherical combustion chamber, said head being provided with two valves disposed with their axes in a plane of symmetry of the combustion chamber, and means for mounting a sparking plug laterally of the plane of symmetry, and a piston whose head, at top dead centre, has a portion corresponding to the shape of the combustion chamber in the zone of one of the valves, and facing the other valve, a concave portion symmetrical relative to the said plane of symmetry.

2. An internal combustion engine comprising a cylinder head, said head having a substantially hemispherical combustion chamber, two valves disposed with their axes in a plane of symmetry of the combustion chamber, and means for mounting a sparking plug laterally of the plane of symmetry, and a piston having a head which, when the piston is at top dead centre, has a portion in the zone of one of the valves with a shape corresponding to the shape of the combustion chamber in the zone of that valve, and a concave portion facing the other valve and occupying a major portion of the combustion chamber, said concave portion being symmetrical about the plane of symmetry.

3. An engine according to claim 1 or claim 2, wherein the concave portion of the piston is situated facing the exhaust valve.

4. An engine according to claim 1 or claim 2, wherein the concave portion of the piston is situated facing the inlet valve.

5. An internal combustion engine substantially as hereinbefore described with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. tion of the combustion chamber defined by the head of the valve 2. The flat portion 7 is bounded by two part-spherical portions 8 and 9 conforming to the outline of the cylinder head 1. The flat portion 7 and the two part-spherical portions 8 and 9 which bound it are connected by a rounded edge 10 to concave recess 11, the whole, including the recess, being symmetrical about the plane x-x. The valve 2 may be the inlet valve, the valve 3 being the exhaust valve. In this case, the engine has a particularly low petrol consumption. Alternatively, the recess 11 may face the inlet valve. In this case, the petrol consumption is slightly increased, but the proportion of pollutants formed will be very small. From the foregoing, it will be apparent that the engine can be adapted to provide low fuel consumption, or low pollutant emission, simply by reversing the mounting of the piston in the cylinder. WHAT WE CLAIM IS:-

1. An internal combustion engine comprising a cylinder head having a substantially hemispherical combustion chamber, said head being provided with two valves disposed with their axes in a plane of symmetry of the combustion chamber, and means for mounting a sparking plug laterally of the plane of symmetry, and a piston whose head, at top dead centre, has a portion corresponding to the shape of the combustion chamber in the zone of one of the valves, and facing the other valve, a concave portion symmetrical relative to the said plane of symmetry.