Fire ring for cylinder head gasket
This invention relates to an internal combustion engine and more particularly to a cylinder head gasket having metal wrapped double wire rings forming the fire ring around the cylinder opening and the combustion chamber of an internal combustion engine. 
     Cylinder head gaskets for an internal combustion engine are normally provided with fire rings around the cylinder opening and the combustion chamber to seal the hot gases from the coolant for cooling the internal combustion engine. The high compression of diesel engines increases the heat and pressure which the gaskets are subjected to and increases the strain. The fire rings are generally metal and wrapped in metal to withstand heat and pressure. The Baugh et al patent, U.S. Pat. No. 4,244,330, and the Meyers et al patent, U.S. Pat. No. 3,473,813, illustrate cylinder head gaskets. The Meyers et al patent shows an non-ferrous material forming the gasket material around the cylinder opening on a diesel engine while the Baugh et al patent shows a single metal hoop wrapped in metal to provide a fire ring on the gasket. A single fire ring, as illustrated in the Baugh et al patent, has been known to operate satisfactorily under ideal conditions with adequate clamp down forces around the fire ring on the gasket. The heat and pressure and changing temperatures can cause deterioration of the gaskets which will in time reduce the sealing qualities of the gasket necessitating retorquing of the cylinder head bolts to restore its sealing quality. Since it is not always known when deterioration of the seal is present, the deterioration may progress to a point where the gasket blows out requiring replacement. 
     The applicant has provided for a reinforced fire ring to withstand the high heat and pressures of the modern diesel engine. A double hoop increases the structural integrity of the fire ring and increases the fire ring strength. A larger inner hoop carries the load and forms a seal between the head and the cylinder sleeve while the smaller outer hoop reinforces the inner hoop and provides greater fire ring strength. 
     It is an object of this invention to provide a cylinder head gasket with greater fire ring strength. 
     It is another object of this invention to provide a cylinder head gasket for an internal combustion engine having double hoops forming the fire ring to increase the strength of the fire ring to reduce gasket blowout. 
     It is a further object of this invention to provide a cylinder head gasket having a metal wrapped double hoop to form the fire ring. The inner hoop is of a larger diameter to carry the clamp down load and form a positive seal between the head and the sleeve. The outer smaller hoop gives added strength to the fire ring to assure seal integrity and prevent blowout. 
     The objects of this invention are accomplished in a cylinder head gasket for an internal combustion engine. The fire ring has a double hoop with a metal wrap to form seal integrity around the combustion chamber. The inner larger hoop carries the clamping load to provide a positive seal while the outer smaller hoop increases the hoop strength and provides greater structural integrity to maintain a more durable fire ring and insure against blowout of the cylinder head gasket. 
    
    
     Referring to the drawings, a preferred embodiment of this invention is illustrated. 
     FIG. 1 illustrates a cross-section view of an internal combustion engine showing the cylinder head gasket in the engine; 
     FIG. 2 is a cross-section view of the cylinder head gasket with the double hoop, metal wrapped fire ring; 
     FIG. 3 illustrates the cylinder head gasket; and 
     FIG. 4 is a modification of the cylinder head gasket shown in FIG. 2. 
    
    
     Referring to the drawings, FIG. 1 illustrates a cross-section of the engine. The engine block 1 receives the cylinder sleeve 2 to form the cylinder receiving the piston 3. Piston 3 is pivotally connected to the crankshaft 5 through the connecting rod 4. The engine head 6 is fastened by means of a plurality of bolts 7. The gasket 8 forms a gas seal between the combustion chamber 9 and the coolant chambers 10 cooling the engine. The gasket 8 is compressively positioned between the head 6, the block 1 and sleeve 2 to form a seal between the hot gases in the combustion chamber 9 and the coolant chamber 10. 
     Referring to FIGS. 2 and 3, the gasket is shown. FIG. 3 shows a plan view of the cylinder head gasket 8 and FIG. 2 shows a cross-section view taken on line II--II of FIG. 3. Block 1 is formed with a bore to receive the sleeve 2. The sleeve is formed with a flange 13 which seats on radial facing 14 formed by the counterbored portion 15 of the block 1. The gasket 8 is positioned between the cylinder head 6, the sleeve 2 and the block 1. Gasket 8 includes the body 16 formed with cylinder openings 17, 18, 19 and 20 having fire rings 11. The fire rings consist of a sealing hoop 21 which is slightly larger than the reinforcing hoop 22. The hoops 21, 22 are encased in a metal wrap 23 which is pressed against the surfaces 24 and 25 of the gasket body. Sealing ring 21 forms a seal as it is compressed between the head 6 and the sleeve 2. Since the reinforcing hoop 22 is slightly smaller than hoop 21, it does not form a seal per se but reinforces the hoop 21 when the cylinder head bolts 7 are torqued at the proper tension. FIG. 4 shows a square reinforcing ring 122. The gasket 8 forms a positive seal between the combustion chamber 9 and the coolant passages.