Internal-combustion engines – Crankcase ventilation
Utility Patent
1999-06-14
2001-01-02
McMahon, Marguerite (Department: 3747)
Internal-combustion engines
Crankcase ventilation
C123S572000
Utility Patent
active
06167849
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to systems and devices for precluding the discharge of oil from lubricated mechanisms, and more specifically to a collector for capturing oil mist and vapor discharged from the crankcase breather of a four stroke (Otto cycle) internal combustion engine. The device comprises a container and filtered exhaust, with the crankcase breather line being connected to an inlet on the container. The present invention is particularly well suited for use with motorcycles having four stroke internal combustion engine power, as such vehicles are not required to have other emission control means of capturing crankcase oil vapor.
2. Description of the Related Art
All four stroke (Otto cycle) reciprocating internal combustion engines produce at least some “blowby” due to the relatively high pressures occurring in the combustion chamber(s) during the compression and power strokes of the engine while it is operating. While the piston(s) is/are normally reasonably well sealed by means of their compression and oil control rings, there will nevertheless always be some compression and combustion pressure which escapes the combustion chamber(s) past the rings and ring gaps, and finds its way to the crankcase of the engine.
The turbulence within the crankcase, due to the spinning of the crankshaft and its throw(s) with the lower end(s) of the connecting rod(s) attached thereto, along with the spray of return oil from various components in the engine, results in a considerable amount of warm oil vapor being contained within the crankcase during engine operation. This blowby gas, with its oil vapor byproduct, must be released from the crankcase in some manner, in order to preclude the blowing out of crankshaft or other seals within the engine.
It has been standard practice for many years on automobiles to run a tube from the crankcase (and valve cover) vent(s), back to the intake system of the vehicle, where the expelled crankcase gases are recycled through the combustion chambers of the engine for combustion. This crankcase ventilation system was the earliest form of emissions control provided on automobiles. Increasing emissions control requirements over the years have led to further emissions control equipment being required for automobiles.
However, due to the weight, bulk, and engine inefficiencies of such emissions control equipment, no emissions control requirements have ever been established for motorcycles. As there are relatively few motorcycles on the road in comparison with automobiles, and motorcycles are generally equipped with relatively smaller engines which put out fewer pollutants than automobile engines, it has generally not been considered to be worthwhile to require such emissions controls (including crankcase ventilation systems) for motorcycles.
Accordingly, crankcase vapors have conventionally been vented to ambient atmosphere during operation of motorcycle engines. The amount of blowby gas and oil vapor is relatively small, but nevertheless some combustion gases and oil vapor are distributed to the atmosphere during the operation of the typical motorcycle, with larger motorcycles with bigger engines contributing a relatively greater share of such gases and vapors. While such gases and oil vapors are an extremely minor part of any contribution to atmospheric pollution, the oil vapors escaping from the crankcase breather tube of such an engine can nevertheless contaminate the immediate area of the motorcycle, by spraying upon various components of the motorcycle. As the oil vapor contacts relatively cooler components on the motorcycle, it will tend to condense and produce an oily film on components downstream of the breather outlet. The film tends to collect dust and dirt, and an otherwise clean motorcycle can become quite grimy and dirty after a road trip of any duration. This is a continually frustrating experience for the typical motorcycle owner who takes pride in his or her machine, with the owner being required to clean the motorcycle after nearly every operation of the machine in order to remove the oil dispensed by the crankcase breather of the motorcycle.
Accordingly, a need will be seen for some means of collecting and retaining oil vapor from a motorcycle engine, which otherwise would be sprayed or distributed over the exterior of the motorcycle during operation of the machine. The oil vapor collecting and retaining means must provide for the positive capture of all vapors emanating from the crankcase breather system, and must also provide for the routing of blowby gases from the collector system after oil has been removed from the gases. The gases may be filtered in order to preclude the passage of any significant amounts of particulate or liquid discharge to the atmosphere.
A discussion of the related art of which the present inventor is aware, and its differences and distinctions from the present invention, is provided below.
U.S. Pat. No. 4,646,701 issued on Mar. 3, 1987 to Tsunenori Fukumoto, titled “Evaporation Fuel Processing Apparatus For Two-Wheel Vehicle,” describes a closed fuel vapor capture system for motorcycles. The fuel vapors are absorbed within an activated charcoal canister, where they are contained until venting into the intake manifold of the engine during engine operation. The present system is open, rather than being closed, and serves to capture oil (not fuel) as it is expelled from the crankcase breather, along with other crankcase gases. The liquid captured by the present system is not rerouted to the engine for recycling, but is retained in a canister for periodic disposal as required.
U.S. Pat. No. 4,727,955 issued on Mar. 1, 1988 to Masazi Honda et al., titled “Carbon Canister Drained Vapor Diffusing Device,” describes a fuel vapor control system in which vapors are released from a canister to a closed channel front subframe member of an automobile. The vapors are then dissipated through passages in the subframe member to the atmosphere. The Honda et al. invention is the provision of a small secondary plenum relatively well removed from the passenger compartment of the vehicle, for accepting the fuel vapors from the canister and dissipating the vapors relatively far away from the passenger compartment in order to minimize fuel odors in the passenger compartment. No mention is made of any means of capturing oil vapor from crankcase blowby gases, or separating liquid oil from blowby gases and dispensing the blowby gases while retaining the oil, as provided by the present invention.
U.S. Pat. No. 5,183,023 issued on Feb. 2, 1993 to John D. Hanson, titled “Evaporative Emission Control System For Supercharged Internal Combustion Engine,” describes a fuel vapor control system in which two lines are provided from the canister to the intake system of the vehicle. The two lines route fuel vapors to the engine either upstream or downstream of the supercharger, depending upon whether the engine is operating at a manifold pressure of more or less than ambient atmospheric pressure. Hanson does not disclose any means of capturing oil vapor from crankcase blowby gases, as provided by the present invention.
U.S. Pat. No. 5,373,830 issued on Dec. 20, 1994 to Helmut Denz et al., titled “Breather For An Internal Combustion Engine Fuel Tank,” describes a fuel vapor capture system including at least one pressure relief valve for venting pressure to ambient in the event the fuel vapor pressure in the system reaches a predetermined point, in order to relieve the pressure before blowout damage to the system occurs. The Denz et al. system is closed until a predetermined pressure is reached, whereupon the pressure relief valve opens. The present system is open to ambient atmospheric pressure at all times. Denz et al. are silent regarding any means of capturing oil vapor from crankcase breather gases, as provided by the present invention.
U.S. Pat. No. 5,562,757 issued on Oct. 8, 1996 to Francois Brun et al., titled “Device For Recovering the Vapors Leaving A Motor Vehicle Ga
Litman Richard C.
McMahon Marguerite
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