This invention relates to internal combustion engines, including but not limited to crankcase ventilation for an internal combustion engine.
Internal combustion engines include crankcases having a plurality of cylinders. The cylinders contain pistons whose reciprocating motion due to combustion events that occur in a variable volume within a plurality of bores in the crankcase that contain the pistons, and the pistons themselves, may be transferred through a crankshaft to yield a torque output of the engine. Often, engine crankcases are made of cast metal, and include passages integrally formed therein for the transfer of various fluids from one location of the engine to another. Fluids typically transferred through passages in an engine include coolant, air, fuel, oil, gases, vapors, and so forth.
During operation of the engine, a mixture of air and fuel combusts in a cylinder, and exhaust gas that is produced by the combustion is released therefrom through one or more exhaust valves. Sometimes, a small quantity of exhaust gas may escape through a seal between the piston and the bore, and enter an internal volume of the crankcase. This small amount of exhaust gas is commonly referred to as “crankcase gas”. The crankcase gas is typically allowed to exit the crankcase in a controlled fashion, and is usually recirculated into the intake system of the engine. Crankcase gas often includes some amount of lubrication oil of the engine. This amount of oil is either vaporized and/or splashed by various engine components during operation, or is just picked up when it sublimes due to heat by the crankcase gas in droplet or gas form as the crankcase gas travels through the crankcase. Devices called “breathers” are used to remove oil from the crankcase gas before it's recirculated into the intake of the engine.
A typical breather device may include a filter or another method that removes oil from the crankcase gas. The more oil that is included in the crankcase gas, the larger and more costly the breather must be to effectively remove the oil that is included in the crankcase gas. Use of breathers is often determined by the size of the engine and the cylinder pressures during combustion. For larger engines, or engines having comparatively high cylinder pressures during operation, for example diesel engines, breathers may become large and costly.
Accordingly, there is a need for an ability to decrease the amount of oil carried with the crankcase gas before the gas reaches the breather, in order to decrease the size and increase the effectiveness of a breather for an engine that would otherwise require a larger breather device. The smaller breather would be easier to fit onto the engine, less costly, and more effective than a breather that would typically be required.
A crankcase for an internal combustion engine includes a first bank of cylinders that has a plurality of cylinder bores formed therein, and a second bank of cylinders that includes an additional plurality of cylinder bores formed therein. The second bank is at an angle with respect to the first bank. A valley structure is located between the first bank and the second bank. A gallery is advantageously located between the first bank, the second bank, and the valley structure. The gallery has at least one rear opening that fluidly connects the gallery to a rear portion of the crankcase. At least one front opening fluidly connects the gallery to a front portion of the crankcase, and at least one breather opening fluidly connects the gallery to an outer valley surface.
The following describes an apparatus for and method of transferring crankcase gases or vapors from and through an internal cavity of a crankcase to an opening for a breather that effectively removes oil droplets from the crankcase gas before reaching the breather.
An outline of a crankcase 100 for an engine is shown in
A set of rear openings 118 may be formed during a casting operation in a rear portion 120 of the crankcase 100. The rear openings 118 may be fluid entrances to a gallery 122 that may be formed by a relatively large core (not shown) during the same casting operation that forms the rear openings 118 and the crankcase 100. A breather opening 124 may be fluidly connected to the gallery 122, and thus, also in fluid communication with the rear openings 118. The gallery 122 is advantageously disposed along an entire length of the crankcase 100, between the bores 104 and the valley structure 106.
A front cross-section view of the crankcase 100 is shown in
A side cross-section view of the crankcase 100 is shown in
The portion of the flow 304 exiting into the timing chain or belt cavity 116 may travel upward and pass through the front opening(s) 210 to enter the gallery 122. Similarly, the remaining portion of the flow 304 at the rear portion 120 may pass through the set of rear openings 188 and enter the gallery 122. The gallery 122 is relatively large with respect to the breather opening 124 to advantageously decelerate the flow of crankcase gases 304 and promote condensation of any oil droplets that may be carried therewith. The decelerated flow 304 may allow an amount of oil that is carried therewith to precipitate into an amount of liquid oil 306, denoted symbolically by vertical-lined thick-crosshatched droplet shapes and pools that may collect in internal crevices of the gallery 122. A portion of the liquid oil 306 that precipitates in the gallery 122 may fill any crevices therein and overflow out of the gallery 122 into a lower region of the engine, for instance into an oil pan (not shown), through the front opening(s) 210, with a remaining portion of the liquid oil 306 exiting the gallery 122 through the set of rear openings 118.
The flow of crankcase gases 304, having precipitated the liquid oil 306, may enter the breather 206 through the breather opening 124, undergo additional filtering, and exit the breather 206 through a breather outlet port 308. Any additional oil that may be precipitated out of the crankcase gases 304 may be collected and returned to the engine through a drain passage (not shown).
When an engine containing the crankcase 100 is fully assembled and operates, a motion of timing chains or belts (not shown) in the cavities 166 may advantageously promote the flow 304 to enter the gallery 122 through the front opening(s) 210 by imparting an upward momentum to the gas as it passes the chains or belts. Moreover, under certain conditions, the liquid oil 306 exiting from the set of rear openings 118 may roll downward and lubricate other engine components, for example gears, that may be disposed at the rear portion 120 of the crankcase 100 when the engine is fully assembled and operates. Additionally, both the rear set of openings 188 and the front opening(s) 210 are sufficiently large to permit support of a casting core (not shown) used to form the gallery 122 during a casting operation for the crankcase 100.
The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.
Number | Name | Date | Kind |
---|---|---|---|
5190005 | Saito et al. | Mar 1993 | A |
5216984 | Shimano et al. | Jun 1993 | A |
6571763 | Bakker | Jun 2003 | B1 |