Internal-combustion engines – Charge forming device – Supercharger
Reexamination Certificate
1999-11-01
2001-09-25
Kamen, Noah P. (Department: 3747)
Internal-combustion engines
Charge forming device
Supercharger
C123S1960CP, C184S006260
Reexamination Certificate
active
06293263
ABSTRACT:
FIELD OF THE INVENTION
Supercharger for internal combustion engines and other applications, and more particularly a low profile supercharger having an oil misting lubrication system and a power drain system for expelling oil out of the case after oil has lubricated the supercharger.
BACKGROUND OF THE INVENTION
Supercharging of internal combustion engines is a well established method of obtaining greater power output from engines of a given size. Due to the extremely high rotational speeds of the compressor, gears, bearing races, and other moving parts of superchargers, it is imperative to maintain adequate lubrication in superchargers. In addition to preventing excessive wear of parts, lubrication aids in cooling of the parts.
In present superchargers, lubrication slingers are commonly used to provide lubrication to the moving part. See for example U.S. Pat. No. 5,638,796 to Adams, III et al., which discloses an electric supercharger with a lubrication slinger, and U.S. Pat. No. 4,171,137 to Aizu et al., which discloses a slinger arrangement for use with the bearing of superchargers. Others indicate, in a general manner, that some oil will be kicked up by the slinging and create an oil mist that will tend to provide some lubrication. See for example U.S. Pat. No. 5,281,116 to Gwin, U.S. Pat. No. 5,241,932 to Everts, U.S. Pat. No. 4,423,710 to Williams, and U.S. Pat. No. 5,579,735 to Todero et al. U.S. Pat. No. 4,752,193 to Horler discloses using the venturi effect created by a turbocharger to aid in evacuating oil that collects at the bottom of the supercharger's gear case.
U.S. Pat. No. 5,375,573 to Bowman disclosing a two-stroke internal combustion engine having a pressurized air rail. The pressurized air rail is for producing an atomized fuel spray for injection into the individual combustion chambers, in which oil for lubrication is atomized by metering it into a stream of compressed air taken from the rail or a reservoir connected thereto and the resulting oil/air mist is injected into the crankcase and/or the lower part of the cylinder selectively and directly onto points requiring lubrication. Bowman discloses that to reduce the load on the air compressor feeding the pressurizing rail, the compressed air supply for the oil atomization may be supplemented by an engine supercharger, if one is utilized. Bowman further states that each cylinder of the engine is provided with a plurality of lubricating jets or nozzles to generally direct atomized oil locally to easily accessible parts and components in a two stroke engine such as the small-end bearings, big-end bearings, the piston skirt and piston ring areas. Bowman does not disclose use of a misting oil/air system for lubricating supercharger bearings, or using a misting oil/air system for lubricating less accessible components such as bearing races press fitted into bearing race cavities in superchargers.
Superchargers are frequently belt driven and have gears in a gear case to substantially gear up the rotational speed so that the compressor of the supercharger will generate sufficient boost. In presently available superchargers, the space inside the gear case is purposely made relatively large, with much space between the gears and the walls of the gear case so that oil can be flung onto the various gears and bearings. However, one side effect of large cases is that oil that accumulates in the bottom of the case to be drained is sometimes whipped up by the gears and become foamy. This foamed oil hinders drainage, and as a result the oil will increase in temperature, and lower the performance of the supercharger.
Although there has been a substantial amount of development work on more efficient designs for superchargers, there remains a need for improved superchargers that are more compact in design, are better lubricated, and that are more durable, more efficient, and readily installable onto different engines.
SUMMARY OF THE INVENTION
The inventor has developed a supercharger that includes certain features that significantly improve the lubrication of its gears and which provides a low profile supercharger. The supercharger unit itself takes filtered air, preferably from a cool location, in-from the center of the compressor wheel which has radial vanes and which accelerate the air. The air, leaving the impeller, is diffused and slowed, thus compressing it before discharging the air essentially tangentially with respect to the vanes. The compressor wheel is located in a shallow bore which is of a depth to receive the base or vane supporting part of the compressor wheel such that the air from the compressor wheel flows smoothly into the volute with no abrupt discontinuity or drop off to create turbulence or eddies.
The supercharger includes a drive shaft that carries an external pulley driven by the associated motor. The drive shaft extends into a drive portion of the supercharger. The drive portion has a gear case containing a larger drive gear that meshes with and drives a smaller driven gear. The gear case has an inner chamber with a back wall, a front wall, and perimeter walls having a swale formed thereon. Drive gear bearing mounting recesses receive drive gear bearing races (or other rolling elements), and driven gear bearing mounting recesses receive driven gear bearing races (or other rolling elements). The driven gear is connected to the compressor through a driven shaft. Both the drive and the driven gears can be standard with the gears representing about a 3.45:1 ratio for increased rotational speed of the compressor wheel, relative to engine speed, and both the drive and driven shafts are carried by bearing races. Of course, other gear ratios can be used. Also, while the supercharger finds a major use in motor vehicles, the supercharger can be used in industrial applications, such as to provide a high volume of high speed air.
To provide for better performance and reliability over wide temperature ranges, the supercharger can also preferably include bearing holding inserts made of metal having similar expansion characteristics to that of the bearings and moving parts so that differential expansion and contraction of the gears, shafts, and bearings, typically made of ferrous materials, and the gear case, typically made of aluminum alloy are compensated, to thereby avoid problematic tolerance changes between the ferrous material parts and the aluminum alloy parts.
The compact supercharger preferably also includes an atomizer for providing a lubricating oil/air mist to the supercharger. One advantage of using an oil/air mist for lubricating the driven gear bearing assemblies is that the oil can be readily sprayed into the bearings, thereby achieving quick and excellent penetration. Further, the pressurized air atomizes the oil and improves distribution and will also assist in driving the oil out of the gear case after it is used, thereby shorting the cycle time of the oil in the gear case, and providing improved lubrication and cooling of the gear case. An oil/air mist inlet is formed in the gear case, and oil/air mist channels are in communication between the oil/air mist inlet and the driven gear bearing races. A splitter with passageways is located near a bottom of the gear case in the vicinity of an oil outlet. The outer circumference of the drive gear is in close proximity to the perimeter walls of the inner chamber and an upper face of the splitter. During rotation of the drive gear, oil/air mist will be expelled against the perimeter wall portion to aid in separating the air from the oil, the oil will travel down the swale and groove, through the passageways of the splitter, and exit through the oil outlet, thereby preventing windage of the oil in the gear case and assisting in power draining of oil from the gear case. Alternately, the supercharger can be used simply with pressurized oil rather than an oil/air mist, in which case oil alone will travel through the channels and be dispelled onto the bearing races.
As noted above, the supercharger of the invention has predominant applications in the ar
Kamen Noah P.
Kelly Bauersfeld Lowry & Kelley LLP
Vortech Engineering, Inc.
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