Internal-combustion engines – Rotary – With compression – combustion – and expansion in a single...
Reexamination Certificate
1998-06-18
2001-06-26
Denion, Thomas (Department: 3748)
Internal-combustion engines
Rotary
With compression, combustion, and expansion in a single...
C123S246000, C418S200000, C418S204000
Reexamination Certificate
active
06250278
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to rotary machines, including rotary engines, rotary motors, and compressors.
BACKGROUND OF THE INVENTION
The advent of rotary engines was intended to supplant reciprocating engines, thereby to reduce energy losses caused by the reciprocation of pistons, to reduce the number of moving parts, and also, friction losses. In this way it was intended to increase the number of revolutions per minute, and also to increase engine efficiency.
Rotary engines may include a pair of rotors arranged for rotation within a sealed engine cavity. The rotors are connected to an output shaft or driver. A combustible fuel mixture is provided to the engine cavity and ignited. An increase in pressure in the engine cavity due to ignition of the fuel-air mixture results in a driving force being applied to the rotors, thereby causing rotation of the driver.
There are also known rotary pumps and motors which have certain similarities to the above-described engine. An indication of the state of the art may be obtained by referring to the following patent publications:
U.S. Pat. No. 3,078,807, entitled Dual-Action Displacement Pump;
French Patent No. 9204757, publication no. 2,690,201;
U.S. Pat. No. 3,726,617, entitled Pump or a Motor Employing a Couple of Rotors in the Shape of Cylinders with an Approximately Cyclic Section; and
U.S. Pat. No. 5,152,683, entitled Double Rotary Piston Positive Displacement Pump with Variable Offset Transmission Means.
The above patents generally do not provide structures which are conducive for use as internal combustion engines.
In the field of internal combustion engines, it is desirable to sustain high operating temperatures, thereby to maximize engine efficiency, in accordance with the well known Carnot Law.
In the field of rotary internal combustion engines, there are known the following publications: U.S. Pat. No. 2,845,909, entitled Rotary Piston Engine, to Pitkanen; and U.S. Pat. No. 4,666,383, entitled Rotary Machine, to Mendler.
Pitkanen teaches a rotary piston engine having a pair of cam-shaped rotors which are arranged for parallel rotation inside an engine casing. Pitkanen is unable to work at high speeds due to the shape of the rotors, and, furthermore, seeks to cool the engine, thereby preventing an increase in temperature which, in Pitkanen's engine, is undesired. This results in an inefficient engine, based on the well known Carnot Law, in which efficiency is proportional to the temperature difference between the interior and exterior of the engine, which Pitkanen does not sustain.
Mendler teaches a rotary piston engine having a pair of cam-shaped rotors which are arranged for parallel rotation inside an engine casing. Each rotor is described in the cited patent (column
8
, lines
1
-
6
) as having “major and minor cylindrical surfaces . . . , each centered on the axis A of the rotor, and diametrically opposed, . . . joined by cylindrical transition surfaces . . . ” Furthermore, a plurality of seals are provided, thereby to provide rotor-to rotor and rotor-to-bore-wall seals (column
7
, lines
62
-
64
). It will be appreciated that, due to the presence of seals, the engine taught by Mendler is not only unable to sustain high rotational speeds, due to friction losses, but also cannot operate at high temperatures, due to the necessary presence of lubricating oil in the engine cavity.
SUMMARY OF THE INVENTION
It is thus an aim of the present invention to provide a rotary machine which is characterized by an increased speed, a reduction in energy losses, and a reduction in emissions caused by the burning of lubrication fluids.
In order to provide the above improvements, there is provided a rotary machine in which plural, cylindrical rotors are provided for rotation within partially overlapping cylindrical bores, formed within a machine housing. The rotors are eccentrically mounted for synchronized, same directional rotation, within their respective bores, and each is arranged to alternately provide intake and exhaustion of working gases, such that each rotor is continually either admitting or exhausting a working gas.
Furthermore, the machine is constructed such that the rotors are cylindrical, each being of internally balanced form. The rotors do not touch each other or any portion of the machine casing at any time, while being positioned so as to define minimal gaps therebetween. Accordingly, a high rotational speed may be developed, thereby obviating the need for seals entirely, and thus further increasing the available speed, and thus the work efficiency of the machine.
While the machine of the invention may be constructed either as a motor or a compressor, it is preferably constructed as an internal combustion engine.
It will thus be appreciated that, the absence of any touching parts obviates the need for lubrication inside the engine casing, thereby enabling relatively high working temperatures to be developed therewithin. In order to take advantage of this, it is desired to form the rotors and the engine casing of a suitable ceramic material, having low thermal expansion and high thermal insulation properties; the use of ceramics for this purpose is facilitated by the fact that none of the moving parts touch, as well as the cylindrical shape and balancing of the rotors. The engine casing and rotors also have mechanical strength adequate for their intended use.
It will be appreciated that the use of ceramic materials having high thermal insulation properties, as described, enables high temperature differences between the interior and exterior of the engine to be sustained, thereby increasing the efficiency of the engine, and also obviates the need for cooling systems which would be very wasteful of energy.
It will also be appreciated that the lack of lubrication inside the engine casing serves to reduce pollution.
There is thus provided, in accordance with a preferred embodiment of the invention, a machine which includes:
a housing having formed therein a generally elongate cavity, the cavity being formed by a pair of adjoining, partially overlapping cylindrical bores, each bore being separated from an adjoining bore by a pair of non-joining partition walls;
a pair of cylindrical rotors arranged in said pair of adjoining bores, each rotor being disposed in one of the bores for synchronized, non-touching and same-directional rotation with the other of the pair of rotors;
a pair of rotor shafts associated with each pair of cylindrical rotors, each rotor shaft extending through one of the bores, and mounted transversely to each rotor so as to provide eccentric rotation thereof in the bore;
a gear assembly and a driver associated with the rotor shafts, the assembly and the driver, cooperating to provide synchronized same directional rotation of the rotor shafts; and
a plurality of gas ports formed in the housing and communicating with the elongate cavity thereof, for permitting selectable intake and exhaust of working gases,
wherein, introduction of a working gas into interactive association with the rotors causes rotation of the pair of rotors and thus also of the driver.
Additionally in accordance with a preferred embodiment of the invention, each bore has a geometric center, and each rotor is mounted for rotation about a rotation axis spaced from the geometric center by a predetermined eccentricity; each cavity is bounded by a pair of parallel wall surfaces transverse to the rotation axis; the plurality of gas ports includes one or more pairs of gas ports provided in communication with each bore, wherein a first of the gas ports is arranged at a first radius from the geometric center and a second of the gas ports is arranged at a second radius from the geometric center, wherein the second radius has a magnitude smaller than that of the first radius; and each rotor is operative to rotate within one of the bores so as to periodically uncover the first port, thereby to enable a flow therethrough of a working gas.
Further in accordance with a preferred embodiment of the present invention, the pair
Denion Thomas
Nguyen Tu M.
Nixon & Vanderhye P.C.
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