Rotary expansible chamber devices – With wear surface treatment or integrally plated wear layer
Reexamination Certificate
2000-12-18
2002-08-20
Vrablik, John J. (Department: 3748)
Rotary expansible chamber devices
With wear surface treatment or integrally plated wear layer
C418S179000, C418S265000
Reexamination Certificate
active
06435851
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally relates to vane pumping machines, and more particularly, to Invar-class iron-nickel based alloys that are used in portions of the vane pumping machine to optimize the operating performance while yielding substantial reductions in the pollution emissions of the machine. The use of Invar-class iron-nickel based alloys ensures that precise clearances are maintained for the non-contact sealing features of the machine described herein.
The overall invention relates to a large class of vane pumping machines comprising all rotary vane (or sliding vane) pumps, compressors, engines, vacuum pumps, blowers, and internal combustion engines.
This class of vane pumping machines includes designs having a rotor with slots with a radial component of alignment with respect to the rotor's axis of rotation, vanes which reciprocate within these slots, and a chamber contour within which the vane tips trace their path as they rotate and reciprocate within their vane slots. In alternate embodiments, the vanes may slide with an axial component of vane motion, or with a vector that includes both axial and radial components. The vanes may also be oriented at any angle in or orthogonal to the plane illustrated, whereby the vanes would also slide with a diagonal motion in addition to any axial or radial components. The vane motion may also have an arcuate component of motion as well. In all cases, the reciprocating vanes extend and retract synchronously with the relative rotation of the rotor and the shape of the chamber surface in such a way as to create cascading cells of compression and/or expansion, thereby providing the essential components of a pumping machine.
Within this class of vane pumping machines are internal combustion engines, which are the focus of the following discussion. Note however that the features and advantages of the later disclosed invention could be applied to any pumping machine.
Typical pollution emissions for internal combustion engines and efforts to reduce such emissions in a particular sliding vane internal combustion engine were described in U.S. Pat. Nos. 5,524,586 and 5,836,282. By way of summary, the oxidation of hydrocarbon fuels at the elevated temperatures and pressures associated with internal combustion engines produce at least three major pollutant types:
(1) Oxides of Nitrogen (NO
x
);
(2) Oxides of Carbon (CO, CO
2
); and
(3) Hydrocarbons (HC)
Carbon dioxide (CO
2
) is a non-toxic necessary by-product of the hydrocarbon combustion process and can only be effectively reduced in absolute output by increasing the overall efficiency of the engine for a given application. The other major pollutants, NO
x
, CO, and HC, contribute significantly to global pollution and are usually the pollutants referred to in engine discussions. Other pollutants, such as aldehydes associated with alcohol fuels and particulate associated with diesel engines, contribute to global pollution as well.
Unfortunately, current production engines are not ideally suited for achieving low pollution emissions within mainstream applications such as automotives. Production engines include piston engines, Wankel rotary engines, and turbine engines, which may be divided into two fundamental categories: positive displacement engines and turbine engines.
In positive displacement engines (piston and Wankel engines) the flow of the fuel-air mixture is segmented into distinct volumes that are completely or almost completely isolated by distinct solid sealing elements (e.g., piston rings in the piston engine and rotor apex seals in the Wankel engine) throughout the engine cycle, creating compression and expansion through physical volume changes within a chamber. In the piston engine, the piston rings, which surround the piston, contact the cylinder block to seal the chamber as the piston reciprocates with the cylinder. In the Wankel engine, the apex seals of the rotor contact the stator housing as the rotor rotates within the stator housing.
Turbine engines, on the other hand, rely on fluid inertia effects to create compression and expansion, without solidly isolating chambers of the fuel-air mixture. Turbine engines, in most applications, offer three advantageous pollution emission-reducing features:
(1) lower peak combustion temperatures;
(2) extended combustion duration; and
(3) leaner fuel-air ratio.
Because of these three features, pollution emissions of NO
x
, CO, and HC are normally lower in a turbine engine than in a piston or Wankel engine. The significantly lower peak combustion temperatures—largely provided by the leaner fuel-air ratio—reduce NO
x
, emissions by reducing the rate of formation of NO
x
, while the extended combustion duration and leaner fuel-air ratio reduce CO and HC emissions through oxidation of these compounds. Some turbine engines incorporate a sophisticated “Double-Cone” burner, or other such mixing devices, to allow adequate premixing of fuel and air prior to combustion, which is important to reducing NO
x
emissions.
Turbine engines, however, are not practical for most mainstream applications (e.g., automobiles) because of high cost, poor partial power performance, and/or low efficiency at small sizes, leaving positive displacement engines, such as the piston and Wankel designs, as the only practical alternative for these mainstream applications.
Unfortunately, commercially available piston and Wankel designs offer poor emissions performance and/or require catalytic converters to reduce emissions. Even with catalytic converters, pollutant output is substantially higher than desired. U.S. Pat. Nos. 5,524,586 and 5,836,282 describe methods of reducing pollution emissions in a positive displacement vane engine toward the scale of the aforementioned advanced turbine engines.
However, even with the above advantages, efforts continue in order to further refine and enhance the performance of the vane machine. Recall that conventional piston and Wankel engines employ contact sealing for the chamber volumes, which requires lubrication within the chambers. Such lubrication has at least two distinct drawbacks. One drawback is that since the lubricant is in the chamber, a petroleum-based lubricant may itself become a source of pollution, both directly and indirectly, as a by-product of the combustion reaction. The second drawback is that while lubricating the contact interface between two components, the lubricant imposes undesirable temperature limitations on the chamber surface, thereby increasing heat transfer and decreasing fuel efficiency. In other words, given the temperature limits of the lubricant, the chamber surface must be kept cool enough to keep the lubricant below the breakdown temperature of the lubricant.
One means of eliminating the lubricant within the chamber is to eliminate the contact seals and replace them with non-contact or gas seals. In the context of the present invention, the gas seal may be comprised of air, compressed air, fuel-air combinations, combusted fuel-air combinations, and exhaust by-products thereof. Further study of the non-contact sealing clearances in the vane engine design highlights the importance of achieving appropriate sealing performance and reliability. However, to achieve the required non-contact sealing clearances in mainstream applications for optimum performance, the problem of the differential thermal expansion of the machine's components must be addressed and solved.
The measure of a material's susceptibility to thermal expansion is expressed as the coefficient of thermal expansion (CTE), which is the change in length per unit length of material for a one degree Centigrade change in temperature. CTE's are generally expressed as millionths of a centimeter, per centimeter, per degree Centigrade, or parts per million (ppm/° C.). The CTE's of steel and aluminum typically used in pumping machines are generally on the order of 11-20 ppm/° C. The higher the CTE the greater the expansion of the material when placed under thermal load, which would obvious
Mallen Research Ltd. Partnership
Volentine & Francos, PLLC
Vrablik John J.
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