POSITIVE DISPLACEMENT ROTARY VANE ENGINE
The present invention is an engine, which includes a positive displacement compression process, a variably fueled, continuous combustor and/or heat exchanger, and a positive displacement, work-producing expander. This arrangement avoids the traditional stochiometric mixture requirements utilized in spark-ignition based engines and the emission problems associated with diesel engines.
This application is a divisional of U.S. Non-Provisional patent application Ser. No. 13/233,073 filed Sep. 15, 2011, which is a divisional of U.S. Non-Provisional patent application Ser. No. 12/043,066 filed Mar. 5, 2008, now U.S. Pat. No. 8,037,863, which claims the benefit of U.S. Provisional Patent Application Ser. No. 60/892,913 filed Mar. 5, 2007, the entireties of which are hereby incorporated herein by reference.
TECHNICAL FIELDThe present invention relates generally to engines. More particularly, this invention relates to positive displacement rotary vane engines.
BACKGROUND OF THE INVENTIONPremixed and direct-injection spark-ignition piston engines operating on the Otto cycle and direct injection engines operating on the diesel cycle represent the bulk of known engines used for motor vehicles. These engines are popular for a variety of reasons but, primarily, they are widely used because they offer reasonable efficiencies for a wide range of power settings. One major disadvantage for spark-ignition engines is that they must operate in a mode in which the ratio of the fuel mass to the air mass in the engine at the combustion stage is near stoichiometric. Thus, to operate at partial power, the engine must be throttled, whereby the pressure on the intake side must be deliberately reduced in order to limit air mass flow rate. This effectively limits the compression ratio and, in turn, the efficiency of the engines. This fact is the basis for the success of the hybrid-electric propulsion system.
The direct-injection spark-ignition and diesel engines are not as limited by this requirement but these two types of engines have significant emissions problems. The problem of varying the mixture ratio away from stoichiometric is solved using high turn-down ratio combustors in Brayton cycle engines based on gas turbine technology. This is possible because the combustion process occurs in a separate physical area of the engine from the compression and expansion, allowing for only part of the air to be burned in combination with the fuel in a highly controlled way. Having a separate physical area where combustion takes place allows the power levels to be controlled by varying only the fuel flow rate to the combustor. The disadvantage to running the Brayton cycle engines at partial power is explained by the fact that known axial flow compressor and turbine systems are inefficient at off-design operating points.
Another disadvantage of conventional piston engines is that the air is ported to the combustion chamber through valves, which limit the ability of the engine to breathe efficiently and introduce pumping losses even with wide open throttle settings.
To combat these problems, many efforts have been made to develop successful high volumetric flow rate positive displacement compressors of the rotary vane type. Previously known engines of the rotary vane type have substantially depended on intermittent spark-ignition and/or fuel injection in a small volume for combustion. This inherently limits the performance in the same way that piston engine performance is limited by combustion stoichiometry.
Additionally, the sealing of rotary vane devices for high temperature applications such as combustion engines has eluded inventors to date and excessive wear has hampered the success of known rotary vane devices of all types. In order to create a successful rotary vane engine, positive sealing of the vanes must occur along the outer edge of each vane, along the sides of each vane, along the base area of each vane and between the rotor and the case. Without proper sealing, adequate compression and expansion cannot take place. Additionally, the high wear rates associated with the centrifugal forces of known rotary vane engines must be reduced for longevity of the device.
Thus it can be seen that needs exist for improvements to combustion engines and particularly those of the rotary vane type. Additionally, it can be seen that needs exist for rotary vane combustion engines that effectively seal the compression and expansion cavities while reducing component wear, such that an extended service rotary vane engine can be implemented. It is to the provision of these needs and others that the present invention is primarily directed.
SUMMARY OF THE INVENTIONIn example forms, the present invention is an engine that employs a positive displacement compression process, a variably fueled, continuous combustor (such as a combustor used in a gas turbine) and/or a heat exchanger, and a positive displacement, work-producing expander. This arrangement avoids the stochiometric mixture requirements with traditional spark-ignition engines based on the entire engine air mass flow rate and the inefficiencies of off-design compressor and turbine performance. Additionally, this arrangement is not compression ratio limited as spark-ignition engines are. Furthermore, the engine of the present invention significantly reduces engine emissions typical with the operation of diesel engines. Example embodiments of this engine as described herein are in the form of a sealable rotary vane device.
In one aspect, the present invention relates to an improvement to a rotary vane internal combustion engine having an external housing and an eccentrically mounted rotor therein. The rotor is operable for rotational movement within the housing to define compression and expansion cavities. The improvement to the engine includes a plurality of blades in mechanical communication with the rotor and extending radially therefrom. The blades are expandable for engagement with at least one interior confronting face of the external housing.
In another aspect, the present invention relates to a rotary vane engine including a cowl that defines an internal chamber and a rotor rotatably mounted with the internal chamber. The rotor includes a plurality of radially configured splines spaced to define slots between successive splines. The engine also includes a plurality of rotary blades and each blade is received in a corresponding one of the slots. The rotary blades are in sliding engagement with the splines. The rotary blades are expandable.
In another aspect, the present invention relates to a rotary vane engine including an external housing defining a hollow chamber therein and a rotor eccentrically mounted within the chamber. The rotor includes a plurality of rotary blades extending radially therefrom. The engine also includes a race that is substantially contained within the rotor. The race is in mechanical engagement with at least a portion of the blades to limit the radial extension of the blades in relation to the rotor.
In still another aspect, the present invention relates to a rotary vane engine including a cowl defining a hollow chamber therein and a rotor eccentrically mounted within the chamber. The rotor includes a plurality of rotary blades extending radially outwardly therefrom for sealing engagement with an interior confronting face of the cowl. At least a portion of the interior face of the cowl defines a substantially exponential curvature.
In yet another aspect, the present invention relates to a continuously combusting rotary vane engine comprising a cowl and a rotor rotatably mounted within the cowl. The rotor includes a plurality of radially mounted blades configured to compress a working fluid from the rotor. The engine also includes a combustor in fluid communication with the cowl to receive compressed working fluid from the rotor. At least a portion of the compressed working fluid is mixed with a fuel source to form a mixture and the mixture is substantially continuously combusted within the combustor.
In another aspect, the present invention relates to a heat powered rotary vane engine including a cowl and a rotor rotatably mounted within the cowl, the rotor having a plurality of radially mounted blades configured to compress a working fluid. The engine also comprises a heat exchanger in fluid communication with the cowl to receive compressed working fluid from the rotor. Energy is transferred from the heat exchanger to at least a portion of the compressed working fluid received therein. Optionally, the heat exchanger is a solar thermal collector.
Is still another aspect, the present invention relates to a rotary vane engine including an external housing defining a hollow chamber therein, a first rotor eccentrically mounted within the chamber, and a second rotor eccentrically mounted within the first rotor. The second rotor includes a plurality of rotary blades extending radially therefrom. The blades extend outwardly through the first rotor to maintain sealing engagement with a confronting interior face of the external housing.
These and other aspects, features and advantages of the invention will be understood with reference to the drawing figures and detailed description herein, and will be realized by means of the various elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following brief description of the drawings and detailed description of the invention are exemplary and explanatory of preferred embodiments of the invention, and are not restrictive of the invention, as claimed.
The present invention may be understood more readily by reference to the following detailed description of the invention taken in connection with the accompanying drawing figures, which form a part of this disclosure. It is to be understood that this invention is not limited to the specific devices, methods, conditions or parameters described and/or shown herein, and that the terminology used herein is for the purpose of describing particular embodiments by way of example only and is not intended to be limiting of the claimed invention. Also, as used in the specification including the appended claims, the singular forms “a,” “an,” and “the” include the plural, and reference to a particular numerical value includes at least that particular value, unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” or “approximately” one particular value and/or to “about” or “approximately” another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another embodiment.
In general, the engine of the present invention includes a plurality of vane-type blades that are radially positioned around an offset axis, in such a way as to allow movement in and out of a slotted rotor as the blades are rotated thereabout. The blade tips ride against and are biased towards a variable radius outer housing or cowl, wherein variable volume gas cavities are formed between the blades and the outer housing. The rotation of the blades provides for compression and expansion of air by their circular movement against the variable radius outer surface. The compression ratio of the various example embodiments as described below is determined primarily by the distance between successive blades and by the precise positioning of the intake port and the combustor ports. The example embodiments shown and described below represent a substantially constant volume combustion device and have been found to exhibit a compression ratio of approximately 15:1; however, the invention also includes embodiments exhibiting higher or lower compression ratios.
With specific reference now to the drawing figures, the operational engine cycle of an engine 10 according to an example embodiment of the present invention is shown in
In example embodiments of the present invention the combustor 50 of the engine 10 only allows for a fraction of the air to be burned while maintaining combustible mixtures necessary for continuous combustion. In this embodiment, the combustor 50, as shown schematically in
A more detailed image of an example embodiment of the engine 10 is depicted in
Referring again to
The rotor 40 is adapted to slidably receive a plurality of expandable vanes or blades 110 between the plurality of splines 100 as shown in
Rather than engaging the splines, the race 120 is fixedly positioned within the cowl 20 and is anchored to the fixed shaft 90; the relationship between the race and shaft can be seen in
In preferred embodiments of the present invention, the curvature of the cowl 20 is in the shape of an exponential curve, as seen in
The optimal shape for the curvature of the cowl 20 and race 120 can be mathematically determined with the following analysis and reference to
ΔR=R(Δθ)(tan β)
For differential changes in the angle θ, this equation can be rewritten as:
dR=(tan β)R(dθ)
For intimate contact between the blade tip and the cowl surface to be maintained, the angle β will be constant not only for the fixed geometry blade but also for the surface upon which it slides. Taking β to be constant and separating the variables yields:
Integrating this equation from a reference starting value of Ro at θ=0 gives:
ln R|RoR=(tan β)θ
or
R=Roe(tan β)θ
Hence the most ideal shape for sealing between the blade tip and cowl with a fixed geometry blade is exponential. To demonstrate the optimal curve shape in another way, the sealing of the blade tips against the cowl can be optimized by recognizing that a short line segment at a practically perpendicular radial line can slide in nearly intimate contact with a cowl containing the rotating vanes if the shape of the cowl is an exponential curve described by the equation:
r=r0ekθ
where “r” is the radius of the curve at a given angle θ from a reference line, “ro” is the reference radius (approximately the radius of the rotor), and “k” is a small constant determined based on desired engine flow rates and mechanical considerations. In addition, the relationship between the curvature of the race 120 and the curvature of the cowl 20 can be represented as:
rcowl=rrace+d
wherein the radius of the cowl at any given point is equal to the radius of a corresponding point on the race plus some constant “d” representing the radial distance between the corresponding points. Therefore, it is preferred, but not required, that race 120 and cowl 20 follow corresponding exponential curves to optimize blade sealing capacity and engine performance.
In order for the blades 110 to optimally seal against the curvature of the cowl 20 as the blades rotate through both the compression and expansion cycles, the tip of each blade 115 is fitted with a blade tip seal 130, as better seen in
Returning to
During operation, the internal components of the engine 10 expand due to the heat from internal combustion, including the cowl, the expansion/compression cavity 30 and the blades 110. Unfortunately, once tight tolerances between these components at startup grow significantly as the components are exposed to high heat. Known rotary vane engines have been unsuccessful in resolving these changes in tolerances, which typically result in increased engine wear and large inefficiencies due to compression losses. The present invention solves this problem by engineering the blades to expand to maintain sealing across a range of thermal expansion and contraction. One such embodiment of an expandable blade is seen in
Numerous other embodiments of expanding blades can be used with the present invention, such as the alternative blade design depicted in
A sectional view of an example engine according to the present invention is depicted in
In example embodiments of the present invention, the engine components are generally made from 4140 hardened steel and the wear surfaces are coated with nitrites to prolong engine use. The blade seals 130, 140 are formed from a bronze alloy and the combustor is formed from stainless steel. In other embodiments, the engine components can be interchangeably formed from stainless steel, hardened steel, chromium alloyed steel, titanium, aluminum, cast iron, high temperature alloys, composite or thermoplastic materials, nickel, and/or other various types of metals and metal alloys. Nothing herein, is intended to limit the present invention to being constructed from a particular type(s) of material and the materials listed above are for example purposes only.
In an alternate embodiment of the present invention, the engine 10 is implemented in the form of a dual rotary vane stage in which partial compression in the first stage is followed by cooling in a specifically designed intercooler such as those found on some turbocharged piston designed automobile engines. The final stage would compress the cooled air further before introducing it into a combustor. The output gases from the combustor would then drive the two stages in series. The two stages would be tied together in a direct drive arrangement to mechanically ensure flow continuity and thus efficiency of compression.
In another alternate embodiment of the present invention, the engine 10′ can include a solar thermal collector 50′ instead of a combustor as described above, as depicted in
In other alternate embodiments, the combustor can be replaced with any known heat exchanger to deliver energy to heat the working fluid. As such, the heat exchanger can be powered by coal fuel, nuclear energy, solar power, etc.
In still another alternate example embodiment, the present invention includes an engine 310 having a dual bodied rotor 340 that is eccentrically mounted within a cowl 320, as seen in
While the invention has been described with reference to preferred and example embodiments, it will be understood by those skilled in the art that a variety of modifications, additions and deletions are within the scope of the invention, as defined by the following claims.
Claims
1. A rotary vane engine comprising:
- an external housing defining a hollow chamber therein;
- a rotor eccentrically mounted within the chamber, the rotor having a plurality of rotary blades extending radially therefrom;
- a race substantially contained within the rotor, the race being in mechanical engagement with at least a portion of the blades to limit the radial extension of the blades in relation to the rotor.
2. A rotary vane engine of claim 1, wherein the engine further comprises a fixed shaft coupled to the housing.
3. A rotary vane engine of claim 2, wherein the race is rigidly coupled to the fixed shaft.
4. The rotary vane engine of claim 3, wherein the rotor is operable for rotational movement about the fixed shaft and race.
5. The rotary vane engine of claim 1, wherein the race limits the radial extension of the blades from a retracted position to an extended position.
6. The rotary vane engine of claim 5, wherein the race comprises a blade guide surface to engage the blades.
7. The rotary vane engine of claim 6, wherein the blades comprise a blade collar for engagement with the blade guide surface.
8. A rotary vane engine comprising:
- a cowl defining a hollow chamber therein; and
- a rotor eccentrically mounted within the chamber, the rotor having a plurality of rotary blades extending radially outwardly therefrom for sealing engagement with an interior confronting face of the cowl;
- wherein at least a portion of the interior face of the cowl defines a substantially exponential curvature;
- wherein the engine further comprises a race substantially contained within the rotor, the race being in mechanical communication with at least a portion of the blades to limit the radial extension of the blades in relation to the rotor, and wherein the race is substantially elliptical in shape.
9. A heat powered rotary vane engine comprising:
- a cowl;
- a rotor rotatably mounted within the cowl, the rotor having a plurality of radially mounted blades configured to compress a working fluid; and
- a heat exchanger in fluid communication with the cowl to receive compressed working fluid from the rotor;
- wherein energy is transferred from the heat exchanger to at least a portion of the compressed working fluid received therein.
10. The heat powered rotary vane engine of claim 9, wherein the heat exchanger is a solar thermal collector.
11. A continuously combusting rotary vane engine comprising:
- a cowl defining an internal curvature;
- a rotor rotatably mounted within the cowl, the rotor having a plurality of blades extending therefrom, wherein an expansion/compression cavity is defined between the cowl and the rotor, the expansion/compression cavity comprising an expansion side wherein a working fluid expands to rotationally drive the rotor, and a compression side wherein the working fluid is compressed by rotation of the rotor;
- a race mounted within the rotor and fixedly positioned relative to the cowl, the race defining a guide surface corresponding to the internal curvature of the cowl and guiding the plurality of blades to maintain sealing contact between seal elements at tip portions of the blades and the internal curvature of the cowl; and
- an external combustor receiving the compressed working fluid from the compression side of the expansion/compression cavity, wherein at least a portion of the compressed working fluid is mixed with a fuel source to form a mixture and the mixture is substantially continuously combusted within the combustor and discharged to the expansion side of the expansion/compression cavity.
12. The continuously combusting rotary vane engine of claim 11, wherein the cowl further comprises an intake port and an exhaust port.
13. The continuously combusting rotary vane engine of claim 12, wherein the expansion side increases in cross-sectional area between the combustor and the exhaust port, and the compression side decreases in cross-sectional area between the intake port and the combustor.
14. The continuously combusting rotary vane engine of claim 13, wherein the cowl and the rotor are axially offset such that the expansion/compression cavity is generally crescent shaped in cross-section.
15. The continuously combusting rotary vane engine of claim 11, wherein the plurality of blades are expandable to maintain contact with the cowl upon rotation of the rotor.
16. The continuously combusting rotary vane engine of claim 11, wherein the race is fixed in position relative to the cowl by a fixed shaft about which the rotor rotates.
17. The continuously combusting rotary vane engine of claim 16, wherein the shaft extends through side plates on both sides of the rotor and is fixed to side portions of the cowl.
18. The continuously combusting rotary vane engine of claim 17, wherein power is output from the rotor through at least one gear operatively coupled to a hub portion of the rotor.
19. The continuously combusting rotary vane engine of claim 11, wherein the race limits radial extension of the plurality of blades to limit frictional contact between the internal curvature of the cowl and the tip portions of the blades.
20. A continuously combusting rotary vane engine comprising:
- a cowl comprising an intake port and an exhaust port;
- a rotor rotatably mounted within the cowl, the rotor and the cowl being axially offset to define a shared expansion/compression cavity comprising a compression side and an expansion side, the shared expansion/compression cavity being in fluid communication with both the intake port and the exhaust port, said rotor comprising a plurality of wedge-shaped splines secured between a pair of rotor side plates and coupled to a rotor hub for transferring power from the engine, said rotor further comprising a plurality of blades slidably mounted within slots between adjacent splines, the rotor side plates sealingly contacting the splines and the blades; and
- an external combustor in fluid communication with the expansion and compression sides of the expansion/compression cavity;
- wherein a working fluid is delivered through the intake port into the compression side of the expansion/compression cavity, compressed in the compression side by rotation of the rotor, mixed with a fuel source to form a mixture and the mixture is substantially continuously combusted within the combustor, discharged from the combustor to the expansion side, expanded through the expansion side to rotationally drive the rotor, and exhausted through the exhaust port.
21. The continuously combusting rotary vane engine of claim 20, wherein the expansion/compression cavity is generally crescent shaped in cross-section, the expansion side tapering from narrower to wider in cross-section between the combustor and the exhaust port, and the compression side tapering from wider to narrower in cross-section between the intake port and the combustor.
22. The continuously combusting rotary vane engine of claim 20, wherein the rotor comprises a plurality expandable blades extending therefrom.
23. A rotary vane engine comprising:
- an external housing defining a hollow chamber therein;
- a first rotor eccentrically mounted within the chamber; and
- a second rotor eccentrically mounted substantially within the first rotor, the second the rotor having a plurality of rotary blades extending radially therefrom;
- wherein the blades extend outwardly through the first rotor to maintain sealing engagement with a confronting interior face of the external housing.
Type: Application
Filed: Sep 24, 2013
Publication Date: Jan 23, 2014
Inventor: Roy J. HARTFIELD, JR. (Auburn, AL)
Application Number: 14/035,457
International Classification: F01C 1/04 (20060101); F02B 55/14 (20060101);