GB2093911A

GB2093911A - Ic engine cylinder head combustion chambers

Info

Publication number: GB2093911A
Application number: GB8106324A
Authority: GB
Original assignee: Ford Motor Co Ltd; Ford Motor Co
Current assignee: Ford Motor Co Ltd; Ford Motor Co
Priority date: 1981-02-27
Filing date: 1981-02-27
Publication date: 1982-09-08
Also published as: JPS6358250B2; JPS58500294A; DE3261500D1; EP0073207A1; WO1982002924A1; EP0073207B1; US4513709A

Description

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GB 2 093 911 A 1

SPECIFICATION

Internal combustion engine and cylinder head therefor

This invention relates to internal combustion 5 engines, and cylinder heads therefor.

Conventional internal combustion engines comprise a cylinder head having a recess therein, a cylinder block having a piston reciprocable in an open-ended cylinder therein, the cylinder being 10 positioned to register with the recess in the head to define a combustion chamber, and inlet and outlet valves mounted in valve openings in the recess for axial movement relative to the cylinder head to open and close the valve openings. 15 It is known to shape the recess e.g. by forming a cusp in one side wall, which projects between the inlet and outlet valves along the range of movement of the inlet valve so as to impart a swirling motion to gases flowing into the 20 combustion chamber through the inlet valve. The swirling motion assists in mixing fuel and air within the combustion chamber and improves combustion.

However, we have observed that such cusps 25 also restrict the free flow of gases into the chamber and therefore reduce the maximum amount of gas which can be drawn into the combustion chamber. The maximum power of the engine is therefore reduced.

30 According to the present invention, there is provided a cylinder head for an internal combustion engine comprising a recess for cooperating with a piston and cylinder in a cylinder block to define a combustion chamber 35 and inlet and outlet apertures for seating inlet and outlet valves, the walls of the recess around the inlet aperture being shaped to impart a swirling action to gases flowing therethrough into the chamber, characterised in that the walls of the 40 recess around the inlet aperture are shaped to impart the swirling action only when the inlet valve is partially open.

Since the walls of the recess are shaped to impart the swirling action only when the inlet 45 valve is partially open, e.g. from one quarter to one half open, gases can flow more freely into the recess when the inlet valve is fully open. Consequently a smaller reduction in maximum power of the engine is achieved. Nevertheless the 50 swirling action imparted to the gases whilst the inlet valve is partially open is sufficient to improve the combustion in the engine.

In the preferred embodiment of the invention, the swirling action is produced by a cusp on one 55 side of the recess which projects radially across the recess between the inlet and outlet apertures, but extends axially from the inlet aperture a distance less than the axial movement of the inlet valve between its open and closed positions. 60 Preferably the distance by which the cusp extends beyond the inlet aperture is no more than half, but preferably at least one quarter of the axial movement of the inlet valve between its open and closed positions.

65 The invention also includes an internal combustion engine incorporating a cylinder head in accordance with the invention.

A preferred embodiment of the invention will now be described, by way of example only with 70 reference to the accompanying drawings, in which:—

Figure 1 is a vertical cross-section through part of an internal combustion engine in accordance with the invention;

75 Figure 2 is a bottom view of a cylinder head incorporated in the engine of Figure 1.

Referring to the drawings, an internal combustion engine 1 comprises a cylinder head 2 having a number of cardiodal recesses, one of 80 which is shown at 3, in its lower surface, secured to a cylinder block 4 having a similar number of pistons 5 and cylinders 6 therein each positioned to register with a respective one of the recesses 3. The space enclosed by the cylinder 6, piston 5 and 85 recess 4 defines a combustion chamber 7. As best seen in Figure 2, fuel and air mixture may be introduced into the combustion chamber 7 through an inlet aperture 8 which is opened and closed by movement of an inlet valve 9, between 90 the two positions indicated in broken lines in Figure 1. The fuel and air mixture can be ignited in the combustion chamber by a sparking plug (not shown) retained in a threaded bore 11 in the roof of the recess 3. The products of combustion may 95 be exhausted from the combustion chamber 7 through an exhaust aperture 12, which is opened and closed by movement of an exhaust valve 13 in a conventional manner.

One side wall of the recess 4 includes a cusp 100 14 which projects between the inlet and outlet apetures 8, 12. As best seen in Figure 1, the cusp extends axially downwardly from the inlet aperture in the roof of the recess 3 by a distance equal to about one third of the movement of the inlet valve 105 9 between its open and closed positions.

In use, when the inlet valve is fully open, air and fuel mixture is free to flow over the cusp 14 into the combustion chamber. As the inlet valve closes however, the air and fuel mixture is directed by the 110 cusp 14 into a swirling motion in the combustion chamber so that the air and fuel is thoroughly mixed immediately prior to combustion.

As a result, the favourable effect of a swirling gas and fuel mixture on combustion is achieved 115 with little adverse influence on the maximum rate of flow gas into the combustion chamber.

Claims

1. A cylinder head for an internal combustion engine comprising a recess for cooperating with a 120 piston and cylinder in a cylinder block to define a combustion chamber, and inlet and outlet apertures for seating inlet and outlet valves, the walls of the recess around the inlet aperture being shaped to impart a swirling action to gases 125 flowing therethrough into the chamber,

characterised in that the walls of the recess around the inlet aperture are shaped to impart the

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GB 2 093 911 A 2

swirling action only when the inlet valve is partially open.

2. A cylinder head according to Claim 1 wherein the recess includes a cusp in one side 5 thereof which projects radially across the recess between the inlet and outlet apertures to impart the said swirling action and extends axially to a distance less than the axial movement of the inlet valve between its open and closed positions.

10

3. A cylinder head according to Claim 2

wherein the said distance is from one half to one quarter of the axial movement of the inlet valve.

4. A cylinder head for an internal combustion engine substantially as hereinbefore described,

15 and as illustrated in the drawings.

5. An internal combustion engine comprising a cylinder head according to any one of Claims 1 to 4 mounted on a cylinder block having a piston and cylinder therein which registers with the recess to

20 define a combustion chamber.

Printed for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, 1982. Published by the Patent Office, 25 Southampton Buildings, London, WC2A 1 AY, from which copies may be obtained