Cylinder head

An exhaust system includes a cylinder head having a plurality of exhaust ports. Integrally formed with the cylinder head are a plurality of independent and separate tubes. The tubes are cast, molded or otherwise integrally formed with the exhaust ports of the cylinder head. The cylinder head and tubes eliminate the need for an exhaust flange, welding the tubes to the exhaust flange and securing the exhaust flange to the cylinder head. As a result, the exhaust system has less weight and improved performance over prior art cylinder head and exhaust assemblies.

FIELD OF THE INVENTION

This invention relates to a cylinder head of an internal combustion engine, and more particularly to a cylinder head with an improved exhaust manifold connection.

BACKGROUND

In an internal combustion engine, the cylinder head is positioned on the top of the engine block. The cylinder head provides upper portions of each combustion chamber, where each upper portion corresponds to one cylinder of the engine block. The cylinder head may house intake valves, exhaust valves, camshafts, rocker arms and pushrods, and numerous other mechanisms as known in the art.

An intake manifold and an exhaust manifold are typically coupled to the cylinder head. The intake manifold is located between the carburetor and cylinder head. In use, the intake manifold supplies an air-fuel mixture through internal intake ports in the cylinder head to each combustion chamber. In multi-port injected engines, the intake manifold holds fuel injectors that supply an air-fuel mixture to each combustion chamber.

The exhaust manifold is typically coupled to the side of the cylinder head opposite the intake manifold (i.e. the “exhaust side”). The exhaust manifold collects exhaust gases exiting from each combustion chamber through internal exhaust ports in the cylinder head and transfers these exhaust gases to an exhaust pipe of an exhaust system. The exhaust manifold has a plurality of primary pipes in fluid communication with a common exhaust pipe. Each primary pipe is coupled to the cylinder head over the outlet of a corresponding exhaust port such that each primary pipe collects exhaust gases exiting a corresponding combustion chamber and transfers them to the exhaust pipe.

The inlet end of each primary pipe is welded to a manifold inlet flange, which is subsequently bolted to the cylinder head. Since exhaust manifolds are generally constructed of cast iron, the inlet flange is relatively heavy and adds a substantial amount of weight to the engine. In addition, welding the primary pipes to the flange is difficult and complicated as it is necessary to provide a weld about the circumference of each pipe. Since there are usually a number of pipes, adjacent pipes interfere with each other during welding. Thus, welding about the entire circumference of each tube is difficult, expensive and time consuming.

Furthermore, once the primary pipes are welded to the flange, a separate machining or smoothing of the flange is required in order to ensure that the cylinder head contacting surface of the flange is smooth and flat, thereby allowing for the secure formation of a sealing attachment of the flange to the cylinder head. The exhaust side of the cylinder head requires similar machining or smoothing in order to provide a corresponding smooth and flat contacting surface of the cylinder head. Since the machining of these materials is difficult and time consuming, the overall cost of producing the engine is higher. Moreover, even with the machining or smoothing of the surfaces, a manifold gasket is required to ensure a good seal between the cylinder head and exhaust manifold. Further, this manifold gasket adds additional weight to the engine, and, over time, the manifold gasket may fail requiring expensive replacement.

Consequently, there exists a significant need for a cylinder head which will provide a reduction in overall engine manufacture time and cost as well as a reduction in engine weight.

DETAILED DESCRIPTION

Referring now toFIG. 1, an exhaust side15of a cylinder head10is shown. The cylinder head10is positionable atop cylinders of the combustion chambers of an engine (not shown). The cylinder head10is important to the performance of the engine as the shape of the combustion chamber, inlet passages and exhaust determine the efficiency of the engine.

Tubes20extend from the exhaust side15of the cylinder head10. Each tube20provides fluid communication between an exhaust port17of the cylinder head10and a primary pipe of an exhaust manifold such that exhaust gases exiting the cylinder head10are transferred through the tubes20into the exhaust manifold (not shown).

In a preferred embodiment, the tubes20are integrally formed with the cylinder head10. For example, the tubes20may be cast into the exhaust side15of the cylinder head10. Advantageously, casting or otherwise integrally forming the tubes20with the cylinder head10eliminates the need for a manifold gasket. In addition, integrally forming the tubes20into the cylinder head10eliminates the need to weld each of the tubes20to the manifold flange and secure the manifold flange to the cylinder head10. Accordingly, integrally forming the tubes20with the cylinder head10provides a manufacturing cost savings over prior art cylinder heads and manifold assemblies.

Each of the tubes20may be integrally formed with one of the exhaust ports17of the cylinder head10such that each combustion chamber of the engine corresponds to one of the tubes20. As a result, the tubes20provides less stress on the cylinder head10than the prior art tubes that are bonded to a flange and bolted to the cylinder head10. The performance of the engine is also improved over the prior art as the interior of the tubes20can remain smoother. For example, in the prior art, the tubes20are welded to a manifold flange resulting in at least a portion of the weld pool blocking exhaust flow through the tubes20. Therefore, the tubes20of the present invention have a smoother interior and increased performance over prior art cylinder head and tube assemblies.

The tubes20may be constructed of metal or a metal alloy, such as, cast iron, cast aluminum, a composite material, or the like. The interior of each tube20may be machined so as to provide a smoother interior surface to reduce energy loss due to wall friction and thereby increase efficiency and engine performance. Also, as shown inFIG. 1, each tube20may be substantially perpendicular to the exhaust side15of the cylinder head10; however, it will be appreciated that each tube20may be at any suitable angle relative to the exhaust side15of the cylinder head10.

Additionally, as shown inFIG. 1, each tube20may have a circular cross-section; however, it will be appreciated that each tube20may have any suitable cross-section, such as elliptical, triangular, rectangular, square, hexagonal, octagonal or the like.

Forming independent tubes20may allow flexibility in system design; for example, in one embodiment, the tubes20may be of substantially different lengths, cross-sections, and/or at different angles relative to the exhaust side15as may required by the overall engine compartment and packing design thereby allowing more flexibility in exhaust manifold design and arrangement. In addition, separate tubes20may act as longer runners thereby permitting better flow separation and scavenging of the exhaust gases prior to the gases entering the exhaust manifold, which may increase overall engine performance. For example, the tubes20may have distinct lengths and each connect to the primary exhaust pipe at different locations.

The distal end30of each of the tubes20is in fluid communication with and coupled to a corresponding primary pipe of the exhaust manifold. Each of the tubes20may be coupled to one another and the primary pipe via a clamp (e.g. band clamp, v-band, Torca™ clamp, etc.), welding, press fit, threaded fit, an adhesive, or in another manner as will be appreciated by a person of ordinary skill in the art. Further, the distal end30of each of the tubes20may be flared so as to telescopically receive a corresponding primary pipe of the exhaust manifold; alternatively, the distal end30of each of the tubes20may be narrowed to be telescopically received by a corresponding primary pipe of the exhaust manifold.

A method for manufacturing and assembling a cylinder head10is also provided. A user may cast, mold, die-cast, or otherwise integrally form the tubes20to the cylinder head10. The tubes20may have predetermined lengths, each of the tubes20have similar lengths of different lengths. The tubes20may be connected to a primary pipe of the exhaust manifold such that exhaust gases exiting the cylinder head10are passed through the tubes20and into the exhaust manifold.

Advantageously, integrally forming the tubes20to the cylinder head10may eliminate the need for an inlet flange on the exhaust manifold and corresponding machining required on the exhaust side15of the cylinder head10, as well as elimination of the manifold gasket, thereby and in part, possibly reducing the number of potential leak paths in the system. Alternatively, the distal end30of each tube20may include a flange that may be coupled to a corresponding inlet flange of an exhaust manifold.

Having shown and described the preferred embodiment, further adaptations of the methods and systems described herein may be accomplished by appropriate modifications by one of ordinary skill in the art without departing from the scope and principles of the present invention. Several potential modifications will become apparent to those skilled in the art. Accordingly, the scope of the present invention should be considered in terms of the following claim and is understood not to be limited to the details of the embodiment shown and described above.