GB2150634A

GB2150634A - Cast i c engine cylinder head

Info

Publication number: GB2150634A
Application number: GB08428494A
Authority: GB
Inventors: Graham Ernest Atkin
Original assignee: Rover Co Ltd
Current assignee: Rover Co Ltd
Priority date: 1983-12-02
Filing date: 1984-11-12
Publication date: 1985-07-03
Also published as: GB8428494D0; GB8332318D0; ES291690Y; ES291690U; EP0146254A1; JPS60192858A; GB2150634B

Description

1 GB 2 150 634A 1

SPECIFICATION

Cylinder head This invention relates to cylinder heads for internal combustion engines.

To form liquid cooling passages in such heads, it is conventional to cast the cylinder head around sand cores which are destroyed when the casting has set to reveal the cooling 75 passages.

However, the use of sand cores has well known disadvantages and it is known to avoid them by using as cooling passages drillings or channels cast into the combustion chamber face of the cylinder head. It has also been proposed (United States Patent Specification

No 3 022 775) to form the cylinder head in multiple sections split about planes perpendi cular to the cylinder axes, in order to provide 85 cooling passages without recourse to sand coring.

It has also been proposed to provide a pair of separate closing members (for each cylin der) attached to the remainder of the head, to define the head water jacket, in order to make the fabrication of the remainder of the head easier (United Kingdom Patent Specification

No. 579 664 and United States Patent Speci fication No. 2 990 819).

It has also been proposed to provide a flat closing disc in the region between inclined inlet and exhaust valves in a head having cooling channels and recesses shaped to be die cast without coring, the closing disc defin- 100 ing a region providing communication be tween the cooling channels. (United Kingdom Patent Specification No. 1 201 363).

The invention provides a cylinder head in which the inlet and exhaust valves for each cylinder are inclined relative to and on oppo site sides of the plane of the cylinder axes, the head comprising a casting having a recess for each cylinder extending, from the face that is opposed to the combustion chamber face, between the inlet and exhaust valves to the region of the associated exhaust port or ports, and a closing member which is inserted into each recess and connected at its periphery to the surface of that recess to define a cooling 115 passage, the closing member having an aperture for insertion of a sparking plug.

The Applicants have discovered that the cooling jacket defined by the closing member can provide a substantial amount of the head cooling for each cylinder, making extensive additional cooling channels and recesses unnecessary, while avoiding the need for sand cores.

Advantageously, the closing member is dished in shape and may be profiled to follow the contour of the adjacent surfaces of the recess, around the periphery that contacts the recess, and/or over its depth. The closing member may be a pressing. The arrangement is particularly suited to four valves per cylinder, and a suitable inclination between inlet and exhaust valves in 40 to 60'.

The sparking plug may be surrounded by a tube, in order to protect it from any oil in the head.

The inlet and exhaust ports may be defined by mould pieces, which are withdrawn from the casting when set: two such pieces may be provided for each port, to be withdrawn from opposite ends of the port, at least one of which may be withdrawn on a curved path.

The casting may be sand or die-cast, preferably pressure die-cast, and should not have undercuts, to facilitate manufacture.

Various drillings may be made in the finished castings, for example to communicate with the cooling passages defined by the casting and the closing member, and to accommodate the valve stems and valve guides.

A four valve per cylinder head for a spark ignition engine and its method of manufacture will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a section through a die for use in manufacture of the head casting, the section being normal to the length of the head (that is, normal to the crankshaft of the as- sembled engine) and thrRugh the plane of a pair of inlet and exhaust valves; Figure 2 is a section through a fragment of the die shown in Figure 1, also normal to the length of the head but through the axis of the sparking plug; Figure 3 is a section through a moulding box into which the die of Figures 1 and 2 is entered, the section being normal to the length of the head and through the plane of a pair of inlet and exhaust valves; Figure 4 shows the die and moulding box of Figures 1 to 3 brought together for casting the head; Figure 5 is a section through the assembled cylinder head, the section being normal to the length of the head and through the plane of a pair of valves; Figure 6 is a section through a fragment of the cylinder head, the section being normal to the length of the head but through the axis of the sparking plug; and Figure 7 is a section through the assembled head, the section being normal to the cylinder axes, and the metal cup and sparking plug being omitted for clarity.

Referring to figures 5 to 7 of the accompanying drawings, the cylinder head comprises a casting 1, the upper face of which is closed by a valve gear cover 2 secured by bolts 3. The head has two inlet valves 4 and two exhaust valves 5 per cylinder in inlet ports 6 and exhaust ports 7, respectively. The valves are driven by respective overhead camshafts 8, 9 via bucket tappets 8 a, g a.

The casting 1 has for each cylinder a recess 2 extending from its upper face to the region of the inlet and exhaust ports 6, 7. A closing member in the form of a metal cup 11 is inserted into the recess and is connected around its periphery to a ledge 11 a on the surface of the recess 10, thereby defining a cooling passage 12 adjacent the valves 4, 5.

Cooling liquid passes through cooling pas sage 12 by means of cast-in recesses 13, 14 and by means of various drillings.

Thus, cooling liquid enters recess 13 (which is closed on the right hand side as seen in figures 5 to 7 by a plate which is not shown) from the block via inlet drillings 15. It passes to the lower part of the cooling passage 12 via drillings 13 a, 13 band 13 c, and also to recess 14 by means of drillings 16. Recess 14 is similarly closed on the right hand side by a plate which is not shown, and liquid passes to the upper part of cooling passage 12 via drillings 14a, 14b and 14c. Liquid flows right to left as seen in the drawings and leaves via wide drilling 17. If desired, addi tional outlet passages could be drilled from the lower part of the cooling passage beneath 90 the drilling 17.

The cup 11 has an aperture for a sparking plug 18 which is protected from the oil in the valve gear region of the head by tube 19. The plug 18 is threaded into a boss 18 a in the casting and the cup 11 seats against the top of the boss around the sparking plug. Thread ing the plug 18 into the boss secures the protective tube in position, and also assists in holding the cup 11 in position.

The valve gear cover 2 seals against a shoulder 19 b on the tube via an 0-ring 19 a.

It will be understood that various operations have to be performed on the casting 1 to complete the cylinder head. The drillings 1 3a to 1 3c, 14a to 14c, and 15 to 17 are made, and drillings are also made for receiving inlet valve guide 28 and exhaust valve guides 28a.

The cup 11 is secured in position. Valve seats 4a and 5a are inserted, the valve guides 28, 28a, valves 4, 5, and tappets 8a, 9a are inserted, and then camshafts 8 and 9 are bolted onto the casting. Finally, tubes 19 are inserted and the sparking plugs 18 are threaded in position. The head is secured to a block by means of cylinder head attachment bolts 30 which may be bolted down on top of the valve gear cover 2, which also has addi tional bolts 3.

The casting 1 is designed without undercuts so that it can be cast easily. Thus, referring to figures 1 to 4, a moulding box 20 receives a die 21 which together form the outer peri phery of the casting and its deep recess 10.

The moulding has sliders 22, 23 which leave spaces for the valve springs (not shown) and mould pieces 24, 25 for the inlet ports and 26, 27 for the outlet ports. Mould pieces 24, 27 and sliders 22, 23 can be withdrawn in a straight line when the casting has set. Mould GB 2 150 634A 2 pieces 25, 26 are withdrawn on a curved path when the casting has set.

The casting is pressure die-cast, but could be gravity die-cast or cast in a sand mould.

The material is aluminium alloy, but other metals or alloys could be used if desired.

The cup 11 is secured in position by a press fit, but it could be secured in position by the wall above it being turned down onto the periphery of the cup (staking). Alternatively the cup 11 could be rivetted, or secured by adhesive such as epoxy adhesive. The cup 11 is an aluminium alloy pressing but other materials could be used.

The cup 11 could be integral with the tube 19, for example, the composite niember could be a casting or a pressing.

Equally the sparking plug 18 need not play any part in securing the cup 11 in position.

Thus, the cup 11 could engage the upstanding wall of the boss 18 a instead of its top surface. The protective tube could also engage the upstanding wall of the boss 1 8a. This arrangement could also be achieved with an integral arrangement of cup 11 and tube 19.

Also, the use of cup 11 is not confined to engines with four valves per cylinder, and could be used with two valves or three valves per cylinder.

Claims

1 A cylinder head in which the inlet and exhaust valves for each cylinder are inclined relative to and on opposite sides of the plane of the cylinder axes, the head comprising a casting having a recess for each cylinder extending, from the face that is opposed to the combustion chamber face, between the inlet and exhaust valves to the region of the associated exhaust port or ports, and a closing member which is inserted into each recess and connected at its periphery to the surface of that recess to define a cooling passage, the closing member having an aperture for insertion of a sparking plug.

2 A cylinder head as claimed in claim 1, wherein the closing member is dished in shape.

3 A cylinder head as claimed in claim 1 or claim 2, wherein the closing member is a pressing.

4 A cylinder head as claimed in any one of claims 1 to 3, wherein the angle between the inlet and exhaust valves lies between 40' and 6 W.

A cylinder head as claimed in any one of ciairns 1 to 4, wherein there are four valves per cylinder and the sparking plug is posi- tioned between the pairs of inlet and exhaust valves.

6 A cylinder head as claimed in any one of claims 1 to 5, wherein a boss is provided for each cylinder in which the sparking plug is positioned, and the closing member connects 3 GB 2 150 634A 3 to the periphery of the boss.

7 A cylinder head as claimed in any one of claims 1 to 6, wherein the inlet and exhaust ports are defined by mould pieces.

8 A cylinder head as claimed in claim 7, wherein there are two mould pieces for each port shapes so that they can be withdrawn from the casting one from each end of the port.

9 A cylinder head as claimed in claim 7 or claim 8, wherein a port is so shaped that a mould piece can be withdrawn from the casting on a curved path.

A cylinder head as claimed in any one of claims 1 to 9, wherein at least one drilling communicates with each cooling passage. 11 A cylinder head substantially as hereinbefore described with reference to the accompanying drawings. 20 12 An internal combustion engine having a cylinder head as claimed in any one of claims 1 to 11.

Printed in the United Kingdom for Her Majesty's Stationery Office, Dd 8818935, 1985, 4235.

Published at The Patent Office, 25 Southampton Buildings, London, WC2A lAY, from which copies may be obtained.