Patent Application
20170284249
The present disclosure is directed to an exhaust system and, more particularly, to an exhaust system having a hybrid cooling arrangement.
Internal combustion engines such as diesel engines, gasoline engines, and gaseous fuel-powered engines combust a mixture of fuel and air to generate a mechanical power output that can be used in many different ways for a variety of purposes. Unfortunately, conventional engines are inefficient, and much of the energy of the fuel is converted to heat. For example, heat can be generated during compression of combustion air directed into the engine or during pumping of fluids (e.g., fuel, air, lubricant, etc.) through the engine. Additional heat is generated directly from combustion of the fuel and air, and is transferred to the engine block and to fluids (oil, coolant, exhaust, etc.) circulating through the block. Most of this heat energy is eventually discharged or otherwise dissipated to the environment.
In some applications, the waste exhaust heat generated as a byproduct of engine operation can be used to drive a turbocharger. The turbocharger increases engine power by forcing more air into the combustion chambers than would otherwise be possible. This increased amount of air allows for enhanced fueling that further increases the power output of the engine.
When a combustion engine is used in a marine application, the engine must adhere to special regulations regarding skin temperature. In particular, a maximum temperature of any outer surface of the engine must remain below an established threshold throughout operation of the engine. The established threshold may be lower than a combustion initiation temperature of elements (e.g., of fuel, oil, etc.) from a surrounding environment that could possibly come into contact with the engine. In order to meet these regulations, hotter parts of the engine are commonly cooled and/or shielded from the environment. Care should be taken during cooling of the engine, however, to ensure that exhaust discharging from the engine is not too low to efficiently drive any associated turbochargers.
U.S. Pat. No. 2,760,593 (the '593 patent) that issued to Hoitt on Aug. 28, 1956 discloses an exemplary exhaust device for a marine internal combustion engine. The exhaust device includes an exhaust manifold, a muffler, an exhaust pipe extending from the exhaust manifold into the muffler, and a water jacket surrounding the exhaust pipe. Water is directed into the water jacket and passes through a spacer member into the muffler, where the water mixes with exhaust from the exhaust pipe and exits the muffler.
Although the water jacket of the '593 patent may help to reduce a temperature of the exhaust pipe, the water jacket may be less than optimal. In particular, the exhaust manifold being uncooled and unshielded, may still have temperatures higher than a threshold regulation. Further, the waterj acket may lower a temperature of the exhaust too far, making use of a turbocharger inefficient or even impossible. Finally, mixing the water with the exhaust could make the water caustic and thereby inhibit recirculation and reuse of the water.
The disclosed exhaust system is directed to overcoming one or more of the problems set forth above and/or other problems of the prior art.
In one aspect, the disclosure is directed toward a coolant adapter for an engine. The coolant adapter may include an elbow-shaped conduit having an exhaust inlet connectable to a cylinder head of the engine and an exhaust outlet connectable to an exhaust manifold of the engine. The coolant adapter may also include a jacket formed around at least a portion of the elbow-shaped conduit.
In another aspect, the disclosure is related to an exhaust system for an engine. The exhaust system may include a plurality of manifold sections, each being connected to an adjacent one of the plurality of manifold sections and thereby forming an exhaust manifold. The exhaust system may also include a plurality of elbow-shaped coolant adapters, each being configured to connect a corresponding one of the plurality of manifold sections to a corresponding cylinder head of the engine and having a coolant jacket formed therein. The exhaust system may further include a heat shield formed around the exhaust manifold.
In yet another aspect, the disclosure is directed toward a power system. The power system may include an engine having a plurality of cylinder heads, and a plurality of manifold sections configured to connect with each other and thereby form an exhaust manifold. Each of the plurality of manifold sections may have an integral exhaust runner extending from an annular wall. The power system may further include a plurality of a coolant adapters, each configured to connect the integral exhaust runner to a corresponding one of the plurality of cylinder heads, and having a jacket formed therein. The power system may additionally include a plurality of couplings, each configured to connect a coolant outlet of the corresponding one of the plurality of cylinder heads with the jacket via an outboard side of a corresponding one of the plurality of coolant adapters. The power system may also include a coolant manifold configured to receive coolant from the plurality of coolant adapters via an inboard side of each of the plurality of coolant adapters, a heat shield formed around the exhaust manifold, and a turbocharger driven by exhaust in the exhaust manifold to pressurize air directed into the engine.
As shown in
Each exhaust manifold 30 may be an assembly of multiple manifold sections 34, which are joined end-to-end in an axial direction. As shown in
Depending on an intended application of engine 12, a skin temperature of exhaust system 14 may need to be lowered in order for engine 12 to be compliant with associated regulations. In the embodiment of
Heat shield 46 may embody any type of heat shield known in the art. In disclosed example, heat shield 46 is a rigid-type of shield. However, it is contemplated that heat shield 46 could be a flexible or a hybrid type of shield if desired. Heat shield 46 may consist of any number of layers (e.g., an outer layer, an inner layer, and one or more intermediate layers) made from any type of material. If multiple layers are included, an inner layer may be fabricated from a reflective material (e.g., foil), an outer layer may be fabricated from a more durable and/or flexible material (e.g., silicon), while any intermediate layer(s) may be fabricated from an insulative material (e.g., a porous or corrugated material).
Heat shield 46 may be installed in sections (e.g., one section per one or more manifold sections 34) and/or in parts (e.g., an inside part and an outside part, a top part and a bottom part, individual walls, etc.), and supported by any surrounding structure (e.g., by manifold sections 34, by mounting flanges 38 and/or 44, by dedicated support structure—not shown, etc.). In some embodiments, heat shield 46 may completely surround each manifold section 34 (e.g., on all four sides—top, bottom, inboard side, outboard side). However, in other embodiments, heat shield 46 may not be required at a location below central conduit 36 (i.e., the bottom may be omitted). Heat shield 46 may terminate at about the distal end of runners 37 (i.e., only be used to lower a temperature of manifold sections 34), as it may be too difficult and/or geometrically complex to install heat shield 46 at lower locations (i.e., locations closer to engine block 16 and between cylinder banks 26 and 28—referring to
Coolant adapter 48 may function to connect runner 37 of manifold section 34 to a corresponding cylinder head 22 (referring to
A coupling 70 may be used to couple coolant inlet 58 of coolant adapter 48 with a supply of coolant. In the disclosed example, the supply of coolant is cylinder head 22. In particular, coupling 70 may be configured to connect an outlet port located at an upper surface of cylinder head 22 with coolant inlet 58. In this example, coupling 70 is an elbow having mounting flanges located at opposing ends. In other examples, however, coupling 70 could have a different shape and/or embody a tube, a flexible hose, or a differently type of coupling, if desired. The coolant received from cylinder head 22 may have already passed through engine 12 and absorbed heat therefrom. A temperature of this coolant, however, may still be low enough to provide an acceptable skin temperature at the associated location. Thereafter, the coolant may exit adapter 48 to join with coolant exiting other adjacent adapters 48 and flow through a coolant manifold 72 to a heat exchanger (e.g., a radiator—not shown) where heat in the coolant may be dissipated to the environment before the coolant is returned to engine 12.
An alternative embodiment of exhaust system 14 is illustrated in
The disclosed exhaust system may be implemented into any power system application where maximum engine skin temperatures are regulated. The disclosed exhaust system may reduce a skin temperature of engine 12 by way of a unique combination of coolant jackets and heat shields. In addition, the disclosed combinations may allow for assembly simplicity and lower costs, without reducing an efficiency of engine 12. In some embodiments, for example in engines employing exhaust recirculation for lower emissions, the disclosed system may also help to reduce a temperature of the exhaust prior to recirculation of the exhaust back to an inlet of the engine.
It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed exhaust system. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed exhaust system. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.
