US2049205A - Composite cylinder head - Google Patents

Description

July 28, 1936.

x COMPOSITE CYLINDER HEAD Filed Aug. 15, 1934 2 Sheets-Sheet l INVENTOR fkmk Jam/m6 iTTORNEY F. JARDINE, $049,205

y 1 5- F. JARDINE COMPOSITE CYLINDER HEAD File d Aug. 15, 1934' 2 Sheets-Sheet 2 INvENfoR [Ta/7k Jhz/wc Patented July 28, 1936 PATENT oFFica 2,049,205 COMPOSITE CYLINDER HEAD Application August 15, 1934, Serial No. 739,918

3 Claims. (Cl. 123-473) The invention relates to cylinder heads for internal combustion engines. It relates particularly to cylinder heads of this nature of composite design, built up from at least two difierent metals which are characterized by a wide Variation in their respective physical properties.

Internal combustion engines using light oils for fuel are now universally familiar and are available to the public in a great variety of designs.

l'O Their most common use lies in the automotive engineering field. Their development in the last thirty years has been rapid and outstanding. Nevertheless there is still ample room for improvement in efliciency as measured by the rela- 15 tion of energy output to input. One of the prin cipal difliculties encountered by engineers centers around the problem of dissipation of ex cess heat generated during combustion of the fuel Most internal combustion engines used in auto- 20 mobiles operate most efliciently at a critical combustion chamber wall temperature characteristic of the engine design but usually varying between 300 F. and 700 F. The great majority of such engines are cooled by a circulating fluid, usually water, held in close contact with the upper parts of the cylinder and the cylinder heads by suitable jacketing arrangements. The proper design of cylinder head should successfully assure two objectives, namely, maintenance of a proper com- 30 bustion chamber temperature, and even distribution of generated heat.

Accordingly, the prime object of the present invention is the design of a cylinder head such that excess heat will be evenly and efiiciently dis- 35 sipated.

Two main types of cylinder head for internal combustion engines have been in use heretofore which I term unitary and composite. By uni-- tary I refer to a cylinder head cast or formed in 40 one piece from one metal, usually having integrally formed passages for cooling fluid or, perhaps, cooling fins for air cooling action. By composite I mean a built-up cylinder head of two or more collaborating parts, possibly of the same 45 metal with cooling passages between, possibly of two or more difierent metals comprising an inner liner adjacent the combustion chamber made from heavy metal of relatively high strength, combined with an outer portion of a lighter metal 50 of relatively high heat conductivity, the outer portion being sometimes provided with cooling fins or containing fluid passages between the two components of the head. These latter composite heads, while representing an improvement over 55 the older art, suffered with the older art a common disadvantage, namely, while the heat might be dissipated rapidly it was not dissipated evenly and it is quite possible to err on the side of too much heat dissipation as too little. The design disclosed hereinbelow permits the heat to be dis- 5 tributed to a surprisingly even extent and the dissipation of heat may be quantitatively regulated in the manner hereinafter shown.

One adaptation of my invention is illustrated in the accompanying drawings, in which Fig. 1 represents a plan view of part of a cylinder head including the upper contour of the several combustion chambers;

Fig. 2 represents a section taken on the line IIII of Fig. 1;

Fig. 3 represents a section taken on the line III-Ill of Fig. 1;

Fig. 4 represents a plan view of part of a cylinder head including the upper contour of several combustion chambers showing individual liners;

Fig. 5 represents a section taken on the line VV of Fig. 4; and

Fig. 6 represents a section taken on the line VIVI of Fig. 4.

As shown in the drawings the cylinder head is built up from two members, II and I2, ll representing an inner liner of metal adjacent to the combustion chamber and forming the upper wall thereof, and I2 representing an outer member which serves as a brace or support for the inner member II and which may also contain the water passages, cooling fins, or other means of heat radiation.

The inner liner II I form from aluminum or aluminum alloy or other metal of high heat conductivity. The outer member I! forming the major portion of the cylinder head I form from a metal of sufficient strength to support the forces bearing on the liner, and of relatively low heat conductivity as compared with the metal 0 of the liner II. The liner H and head [2 fit snugly together and may be held in place on the cylinder block by suitable stud bolts or other arrangement. The liner may even be formed to a satisfactory fit by casting it in place in a mold in which the member l2 forms one wall of the casting cavity and the liner ll may be formed to any suitable thickness by properly forming the casting cavity in manner well known in the art. This is merely one method of forming the liner since it may be forged or pressed in suitably formed dies or cast in sand or metal molds as best suits the occasion. The liner may, and preferably does, cover more than one cylinder since the usual automobile engine has four or more cylinders in line in one block. In most cases it is desirable for proper heat distribution that the liner extend the full length of the engine block and form the finished surface which contacts the cylinder block in an assembled engine, as shown in Figs. 1, 2, and 3. One modification of my invention, however, contemplates the use of an individual liner for each combustion chamber in a multi-cylinder engine, as shown in Figs. 4, 5, and 6. In this latter case the-liner ll preferably does not extend further than the combustion chamber and the thickness thereof is finished with and forms a part of the surface which has to contact the cylinder block.

Cylinder heads as designed up until the time of the present invention were of varying section thickness necessitated by certain factors such as presence of water chambers, spark plug bosses, valve guide bosses, etc. The member adjacent the combustion chamber in a composite design was invariably made of a ferrous metal alloy to withstand heat and pressure while the light alloys, if used at all, were used as outer members to radiate the excess heat. The ferrous metal is relatively a poor heat conductor and certain sections of varying thickness caused local hot-spots" by reason by inability of the ferrous metal to conduct the heat away evenly and rapidly. This sometimes became serious enough to cause pre-ignition or severe local carbonization.

As a result of my invention wherein a liner of metal of high heat conductivity, such as aluminum or an aluminum alloy, is placed next to the combustion chamber, the heat generated is immediately distributed evenly over. the whole head of the engine, and especially over each separate combustion chamber so that local hot-spots are eliminated. The assembly of course may be pierced for spark plugs or other required apertures may be formed therein.

Since the high conductivity liner, or "heat equalizer", is backed up by a ferrous metal outer head, the heat flow from the combustion chamber, while equalized, is moderated, so that the engine is not subjected to the extreme of too rapid heat abstraction. Where liquid cooling is used the liquid passages may be permitted to contact,

, if desired, with the inner liner at points not immediately above the combustion chamber, or, if desired, the water passages may be completely contained within the ferrous metal head. By suitably varying the thickness of the high heat conductivity liner, varying degrees of heat abstraction may be obtained to suit the proper and desired working temperature of the motor. The liner may be fitted snugly to the ferrous metal head with a metal-to-metal contact or the members may contain therebetween a flller or cement of any material of desired thermal conductivity.

In addition to its function in restraining an immoderate heat flow from the combustion chamber the outer member in my combination cylinder head serves as a backing-up or strengthening member to support the inner liner under the severe variable stresses set up during the operation of the motor. For this reason the liner may be made of any desired section thickness with consequent positive control of the heat flow. A liner of moderate thickness, for instance about to inch, should be adequate for ordinary requirements. It may, however, be thinner or thicker than these dimensions.

In this specification and the appended claims wherever the term aluminum is used it'contemplates not only the metal of commercial purity, but also alloys thereof with other metals.

I claim:

1. A cylinder head for an internal combustion engine having a plurality of cylinders comprising an external member formed of a metal of relatively low heat conductivity and provided with heat-abstracting means, an internal liner of aluminum adapted to form a substantial portion of the combustion chamber of each cylinder and forming a path of high heat conductivity from cylinder to cylinder whereby the temperature of the individual combustion chambers is substantlally equalized, said liner being in close contact with said external member and adapted uniformly to conduct the heat of combustion to said external member.

2. "A cylinder. head for an internal combustion engine having a plurality of cylinders, comprising an external ferrous supporting member provided with passages for the circulation of a fluid cooling medium, an internal liner of aluminum adapted to form a substantial portion of the combustion chamber of each cylinder and forming a path of high heat conductivity between adjacent chambers whereby the temperature of the individual combustion chambers is substantially equalized, said liner being in close contact with said external member and adapted uniformly to conduct the heat of combustion to said external member.

3. An internal combustion engine having a plurality of cylinders, meansfor equalizing the heat of the combustion chambers of the several cylin- Y ders comprising an aluminum liner of substantial FRANK J ARDINE.

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