Patent Application
20070065326
The present invention is a rotary piston and more particularly a rotary piston that is scalable, operates over a broad range of pressure and volume combinations for a working substance and can be used as a turbine, pump or compressor.
A rotary piston operates essentially like an infinitely long piston. In a piston, the work is done by a force exerted on a boundary face which separates an enclosed high-pressure chamber from a low pressure potential. As the high pressure drives the boundary face toward the low pressure, work is done. During this movement, the volume of the enclosed chamber containing the high pressure increases and the pressure decreases. Working force and motion continues until the enclosed chamber volume has expanded sufficiently to create equalized pressure on both sides of the boundary face.
Typically, a conventional piston is very difficult to scale and therefore it has not been practical to design pistons that are very large or very small. Making a conventional piston very large is not practical because as the piston chamber increases in size, so does the size of the piston, and its relative mass. Reciprocation of such a large mass is inefficient and becomes impractical. Making a conventional piston very small is also not practical because the seal rings around the circumference of the piston become a dominant component with respect to the area of the piston face. Further, a crankshaft can only reduce to a point before the piston's travel is impaired.
A conventional bladed turbine design only operates efficiently for a large flow volume and a high-pressure differential. Conventional turbines are not adaptable to a dynamic pressure and flow situation.
A rotary piston that is scalable from nano-scopic to giga-scopic domains and is capable of operating efficiently over a broad range of pressure and volume combinations for a variety of working substances is presented. A stator housing having fixed internal dimensions is divided into at least one chamber having seal boundaries in communication with a rotor body and a vane body. The vane body is compressible and has a maximum length dimension to create a low friction seal with the fixed internal dimension of the stator housing for the at least one chamber.
The rotor body located in the stator housing has a slot therethrough in which the vane body is located. The vane body will slide within the vane slot during rotation and can have a small clearance to the stator housing, no clearance with the stator housing, or it can slightly compress against the stator housing.
In one embodiment, a feed control system delivers a working substance to the at least one chamber and the working substance is expanded from a high pressure and low volume to a low pressure and large volume in the at least one chamber. The feed control system is capable of controlling the feed rate and volume of working substance delivered to the chamber.
A cross section of a rotary piston 10 that is scalable in dimension from nano-scopic to giga-scopic domains is shown in
The stator housing 12 is shown in greater detail in
The internal dimensions and characteristics, such as the number of chambers, the volume of the chambers, the profile of the chambers, etc., in the stator housing are a function of the application for the rotary piston 10 and are not limited to the embodiment shown in the Figures. However, the fixed internal dimension 14 of the stator housing requires that the dimension of any line, L1 and L2 in
Referring again to
The rotor body 26 has at least one vane slot 34 intersecting the center channel 30 and axis of rotation 32. Two rotor arms and one vane slot are shown in
Referring to
Referring again to
The vane body 36 has a maximum length dimension 50 and the length dimension of the vane body 36 is slightly compressible. During rotation, pressure from the working substance equalizes the vane body 36 to the maximum length dimension 50 so that any forces exerted on the vane body 36 are equal and in opposite directions. This allows the vane body 36 to float in the vane slot 34.
Referring again to
As discussed above, the compressibility of the vane body 38 provides a smoother vane rotation for the rotary piston. For a given chamber the vane extends outward from the rotor body between the minimum chamber volume and a mid-stroke position. From the mid-stroke position to the maximum chamber volume, the vane is pushed back into the rotor body by the decreasing chamber. The transition of the vane body 38 between extending, stopping and then being pushed back in, requires damping to eliminate vibrations. The compressible, maximum-length vane body 38 of the present invention provides the necessary damping. A rigid, fixed-length vane operated at very low rpm's could provide a seal. However, the rigid, fixed-length vane operated at higher rpm's would generate vibrations and efficiency losses due to the dynamic forces.
The head portions 44 and 46 of the vane body 38 receive the force and perform the compression of a working substance within the chamber 16. The head portions 44 and 46 do work simultaneously by adding a force moment perpendicular to a torque arm created by the vane body 38 and the rotor body 26. The moment of force from each head is a sinusoidal function of rotation, as it is perpendicular to the face portion and proportional to the exposed face area. This moment of force function is exactly the same for each head portion 44 and 46 but is 180 degrees out of phase. The net force and torque applied to the rotor is the vector sum of these two force functions.
Sliding friction reduction is necessary on the back portion 40 of the head portion. Depending on the direction of rotation, the force applied to the face portion 42 of the head portion 44 pushes the back body portion 40 of the vane body 38 towards the rotor body vane slot 34. The vane body 38 floats inside the vane slot 34 and the fixed maximum length dimension establishes a good low-friction seal with the inside of the stator housing 12.
In a turbine application for the rotary piston 10 of the present invention, the working substance is delivered to the chamber 16 using a feed control system 56 shown in
The feed control system 56 can be manual or automated. The feed control system 56 delivers a predetermined, or metered, amount of working substance to the chamber at some point between minimum chamber volume and full chamber volume for the chamber 16. It can be delivered all at once, or metered throughout the piston's revolution. Delivery can be delayed, or it can be commenced exactly at minimum chamber volume 52. The delivery method and amount of working substance depends on the particular design and application for the rotary piston 10. The delivery method and amount will determine a delivery profile and ultimately a working expansion profile of the working substance in the chamber.
Referring to
According to one embodiment of the present invention, the feed control system 56 delivers a high pressure compressible fluid into each chamber 16 beginning at the minimum chamber volume 52. Ideally and in a perfect design, at the minimum chamber volume, the chamber volume is zero, there is no flow and there is an absence of any pressure differential between the dispenser 60 and the pressure inside the chamber 16. As the pressure of the high-pressure fluid drives the chamber 16 from a small volume to a larger volume, expanding the chamber 16, the working substance is continually fed into the chamber 16. No expansion of the working substance takes place during this particular stage and the pressure inside the chamber 16 remains the same as the working substance source. The work product of this particular stage of the turbine is equal to the product of the pressure and the volume of the chamber.
When the feed is stopped, the pressurized working substance in the chamber continues to expand, producing additional work. Expansion of the working substance inside the expansion chamber continues until the full chamber volume 54 is reached. Rotation beyond full chamber volume 54 exhausts the working substance. The coefficient of expansion for the working substance is equal to the chamber volume divided by the predetermined volume of the working substance delivered by the feed control system.
It may be desirable to expand the working substance into a variety of situations. For example, depending on the application, the output desired, or other factors, the working substance may be completely expanded to ambient pressure, in which case the pressure at full chamber volume is equal to ambient pressure. It may be desirable to under-expand the working substance, in which case the chamber pressure at full chamber volume is greater than ambient. Further, it may be desirable to over-expand the working substance, in which case, the chamber pressure at cull chamber volume is less than ambient.
In any event, the feed control system 56 delivers a predetermined amount of high-pressure working substance to the chamber at any point between the minimum chamber volume and the full chamber volume to control the applied volume flow rate of the working substance and to manage the coefficient of expansion within the expansion chamber.
The present invention is advantageous in that it is completely scalable. The present invention, rather than being infinitely long, has working face that travels in a circle without reciprocation. There is no impact on the frequency of cycle because there is no reciprocation of mass. Therefore, the rotary piston of the present invention can be scaled to large dimensions without the drawback of traditional pistons. Further, the sealing edges scale proportionally to the scale of the working face, so scaling to very small sizes is also possible and practical with the present invention.
In a traditional turbine, low volume flow rate can only be accommodated by scaling the turbine to smaller dimensions, a micro-turbine. However, this is expensive and introduces parasitic inefficiencies that do not matter in large turbines, but become dominant factors in smaller turbines.
In a traditional turbine, maximum efficiency is accomplished by complete expansion of the working substance from a high pressure potential to a low pressure potential, which exists across the turbine itself. Complete expansion in a traditional turbine can only be accomplished by designing a physical turbine dimension and geometry to a steady state application of pressure and volume.
According to the present invention, the feed control system produces a dynamic pressure and flow situation. Feed control in the present invention manages the portion size of high-pressure working substance delivered to the chamber so that complete expansion is always possible, even for dynamic input conditions. Sensors 62 can be employed to sense changes in predetermined parameters, such as pressure inside the chamber, to allow the feed controller 58 to adjust flow rate and volume of the working substance into the chamber 16. This feature of the present invention provides a single design for a turbine that is capable of operating efficiently over a broad range of pressure and volume combinations and can be dynamically adjusted during its operation.
An example for the application of feed control of the present invention can be explained using the example of converting the potential work stored in a container of compressed gas, into shaft work in order to run a generator or drive gear. In this application, the incoming pressure decreases as the system is used. With feed control of the present invention, the pressure drop can be sensed and the portion size delivered to the chamber can be adjusted to provide steady state torque and rpm output, while maintaining maximum expansion efficiency. It is also possible to incorporate volume control to determine how much work out is provided at any given time. This output may be steady state, or a dynamic requirement that ranges from zero to a maximum output.
The present invention is efficient over a broad range of pressure differentials because it operates functionally like a piston that has a frictionless ring seal. Therefore, a very low pressure potential can be converted into work as efficiently as if it were a very high pressure potential. The work is equal to the force on the exposed face multiplied by the distance of motion. For a pressure source, which is only slightly higher than ambient, the force is small. However with a large working face, the actual work output can be large. For example, using wind at a speed of 25 mph, only a fraction of a psi is generated. Regardless of the low pressure, a large rotary turbine of the present invention could efficiently convert this force into usable work more efficiently than a conventional windmill. Because the rotary piston of the present invention can extract work form a dynamic source maintaining a fixed efficiency of conversion over a very broad range of pressure and flow volumes.
In one embodiment of the present invention, the rotary piston is operated as a pump to shift, transfer or compress a working substance from a large volume to a small volume. Operating as a pump, the rotary piston can compress a working substance to produce work that can be used to power another machine. Referring to
In another embodiment of the present invention, the rotary piston is operated as a turbine. Referring again to
As the piston rotates 208, the chamber volume increases 210 until the full chamber volume is reached. At this point, there is no rotational force from the rotor body and the chamber is sealed at each end by the rotor arm to the stator housing. Further rotation of the rotor body will open 212 the chamber on the following seal boundary to the exhaust channel, which follows the rotor body, thereby exhausting 214 the working substance through the exhaust channel.
The method 200 of the present invention is capable of dynamic adjustment using the feed control system. The delivery of the working substance is controlled such that the rate of delivery, the volume delivered, and the coefficient of expansion of the working substance can all be controlled as desired to produce a desired output. As discussed earlier, the working substance delivery can be adjusted as desired. It can begin and end at any point between minimum chamber volume and full chamber volume. The rate and volume of the working substance delivery can be controlled as well.
There are several advantages associated with the present invention and applications are too numerous to mention herein. Some examples of advantages are the variety of applications that the rotary piston can be applied to. Further, the ability to scale the system's geometry presents opportunities that have not yet been available to the application of a rotary piston. For example, nano-scopic to giga-scopic turbines.
Several configurations of the rotary piston can be accomplished through varying the physical aspects of the piston. The rotor length, the rotor's internal and external dimensions and geometry, the pressure differential of the working substance, the number of stator nodes, the geometry of the stator nodes, the number and geometry of the rotor arms and channels, the geometry of the torque vane heads and body, number and geometry of the torque vane channels, as well as the rpm of the rotation of the piston.
Some general advantages not yet mentioned include a high conversion efficiency from fluid work into shaft work is accomplished for even low-pressure potentials and for varying input pressure and volume combinations. The rotary piston is capable of operating at low rpm's and provides a constant power stroke or compression stroke. It is relatively inexpensive to manufacture because there a few moving parts and they have specific, focused wear locations. Furthermore, this particular feature results in a rotary piston that is easily serviced. This also allows the material used to manufacture the piston to be either standard materials or exotic component materials. While exotic materials may not be suitable in a piston engine or conventional turbine applications, they may be used in other applications to attain a greater thermal or mechanical range of operation.
The working substance can be either a liquid or a gas because of the high seal capabilities. The operation is independent of temperature, and is limited only by the limitations associated with the materials used. As discussed above, the design can be either a fixed stator, rotating rotor or a fixed rotor, rotating stator design and there is no need for a flywheel or high ratio gearing. There are no vibrations resulting from reciprocating motion.
It can be seen that there has been presented a new and improved rotary piston.
