Patent Application
20060086327
Not Applicable
Not Applicable
1. Field of the Invention
This invention is in the field of locomotive diesel engines,
2. Background Art
There are several problems related to the way in which an engine frame, cylinder head, cylinder liner, and water jacket are assembled, in any internal combustion engine which utilizes a separate cylinder liner. One of these problems is the leakage of coolant. The mating surfaces between an engine block or cylinder liner and the related cylinder head are typically subject to some leakage of products of combustion, as well as coolant, especially in high compression diesel engines used for locomotive applications. These surfaces are commonly mated with a head gasket in between, and the head gasket is often subject to exposure to high temperature and high pressure combustion products from the combustion chamber, accelerating gasket wear and the attendant leakage of coolant and combustion products.
More specifically, it is typically necessary to provide for flow of engine coolant between the cylinder head and the area surrounding the cylinder liner, in order to remove excess heat from the area surrounding the combustion chamber. Flow passages between this area and the cylinder head are subject to some leakage of coolant, especially where the coolant passages are sealed only by the head gasket. This is because the head gasket is subjected to the aforementioned high combustion pressure and temperature, and the gasket can deteriorate as a result of this pressure and temperature. This deterioration of the head gasket can ultimately result in coolant leakage.
Another problem associated with this type of engine is the inefficient removal of excess heat from the area surrounding the combustion chamber, which can result in hot spots, stress concentrations, and accelerated component wear. Cooling must be provided to any component which forms a part of the combustion chamber, because these components are directly contacted by the high temperature products of combustion. In the type of engine being addressed, this requires providing cooling for the cylinder head and the cylinder liner. Typically, the same coolant is circulated in contact with the cylinder head and the cylinder liner, with flow between these two components and a heat removal device such as a radiator. In providing flow of the coolant to the area surrounding the cylinder liner, if the coolant flow is restricted to contact only with the portion of the cylinder liner below the topmost position of the top piston ring, the removal of excess heat from the combustion chamber can be inefficient. This is because the combustion initiates at the top of the combustion chamber, next to the cylinder head, above the topmost position of the top piston ring, and the top of the cylinder liner will typically be hotter than the lower portions. So, a lower efficiency of heat removal results from circulating the coolant in contact with a relatively low portion of the outer surface of the cylinder liner.
A further problem associated with this type of engine is accelerated wear of the structural components of the engine, which can result from the repetitive loads imposed on the components by repetitive firing of the cylinder. Specifically, the cylinder liner is typically held in position by being compressed between the cylinder head and an engine frame. In other words, the cylinder head and the engine frame are usually bolted together, with the cylinder liner clamped therebetween. Typically, the engine frame and the cylinder head also hold the water jacket in place relative to the cylinder liner. The cylinder liner can experience advanced wear where it abuts the engine frame, because of repetitive combustion loads on the cylinder liner.
The present invention includes an engine power assembly having a cylinder head, an engine frame, a cylinder liner, and a water jacket. The cylinder liner is supported by abutting the water jacket, which in turn abuts the engine frame. The cylinder liner does not directly abut the engine frame. This elimination of direct abutment of the cylinder liner against the engine frame minimizes the aforementioned wear of the cylinder liner.
Also, a coolant passage is provided between the water jacket and the cylinder liner, adjacent the top end of the cylinder liner at the topmost position of the top piston ring. This maximizes cooling by circulating coolant against the outer surface of the cylinder liner at the same height as the location of the initiation of combustion, which occurs at the top of the cylinder above the topmost position of the top piston ring.
Further, coolant ports are provided in the cylinder head and the top of the water jacket, to conduct coolant directly between the cylinder head and the water jacket, without passing through the cylinder liner or any other component. Seals are provided in these coolant ports, separate from the head gasket. These seals seal against coolant leakage between the cylinder head and the water jacket, without reliance on the head gasket.
Finally, seals are provided at the upper and lower portions of the cylinder liner, above and below the coolant passage. The upper seal seals between the cylinder liner and the water jacket, while the lower seal seals between the cylinder liner and the engine frame. A fire ring is provided between the combustion chamber and the head gasket, thus protecting the head gasket from accelerated wear by direct exposure to the high temperature products of combustion.
The novel features of this invention, as well as the invention itself, will be best understood from the attached drawings, taken along with the following description, in which similar reference characters refer to similar parts, and in which:
As shown in
The fire ring 20 is provided at the joint between the cylinder liner 16 and the cylinder head 12, to protect the head gasket from damage by exposure to hot combustion gases. A piston 38 is shown at a lower position, for the sake of clarity. In operation, the piston 38 rises to an uppermost position at top dead center, where the upper piston ring 40 is positioned at approximately the height 26 shown relative to the cylinder liner 16. A coolant passage 32 is provided between the cylinder liner 16 and the water jacket 18. The coolant passage 32 extends at least as high as the uppermost position 26 of the piston ring 40. This provides a maximum cooling effect by circulating coolant against the outer surface of the cylinder liner 16 at the approximate height where combustion initiates. A baffle 34 on the external surface of the cylinder liner 16 extends into the coolant passage 32, to eliminate laminar flow and promote heat transfer away from the cylinder liner 16.
An upper liner seal 28 is provided in an upper groove on the external surface of the cylinder liner 16, to seal between the upper end of the cylinder liner 16 and the water jacket 18. A lower liner seal 30 is provided in a lower groove on the external surface of the cylinder liner 16, to seal between a lower portion of the cylinder liner 16 and the water jacket 18. A second lower liner seal 36 may be provided in a second lower groove on the external surface of the cylinder liner 16, to seal between a lower portion of the cylinder liner 16 and the engine frame 14.
As shown in
While the particular invention as herein shown and disclosed in detail is fully capable of obtaining the objects and providing the advantages hereinbefore stated, it is to be understood that this disclosure is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended other than as described in the appended claims.
