1. Field of the Invention
This invention relates to a rotary machine that can be implemented as a compressor, pump, motor or combustion engine. This machine is mainly intended for use as an internal combustion engine.
2. Description of the Prior Art
Most internal combustion engines nowadays use reciprocating pistons. This design has severe inherent limitations: pressure and torque arm out of phase, high “inertial” forces between components due to acceleration/deceleration of pistons and change of trajectory of connecting rods, and expansion ratio tied to the compression ratio. Such limitations reduce performance, increase friction and wear, and reduce energy efficiency.
Many rotary designs have been proposed to overcome the inherent limitations of reciprocating engines. Although relegated to niche markets, the Wankel engine has probably been the most successful in commercial terms. Technically speaking, the Wankel engine has not completely solved old problems like friction and wear, and has problems of its own, especially low torque and troublesome sealing.
My invention is more related to toroidal engines, recent examples of which are found in U.S. Pat. No. 5,645,027 (Esmailzadeh); U.S. Pat. No. 6,276,329 (Archer); and U.S. Pat. No. 6,546,908 (Pekau).
Toroidal engines use pistons revolving in a toroidal chamber intersected by walls or valves. Generally speaking, compression is achieved by advancing the pistons against said walls/valves while deviating the compressed fluid to a separate chamber. At the end of the compression stroke, the intersecting wall/valve briefly retracts/opens to allow the piston pass by/through. In the meantime, combustion is started in the separate chamber. Combustion gases are then released behind the piston.
A key problem in prior art toroidal engines is the loss of compressed fluid during the opening and closing of the walls/valves. Such loss has an important toll on power output and energy efficiency, as it reduces the fuel-burning capacity of the engine, and at the same time increases the pumping power requirements for the compression and exhaust strokes.
Recent designs, disclosed in the already mentioned patents to Archer and to Pekau, have seemingly reduced compression losses to manageable levels. Archer's approach consists of very short pistons and an intersecting valve made of two counter-rotating discs. Pekau has instead modified the shape of the pistons in order to better match the intersecting valve, which is a single rotating disc.
The starting point of my approach has been to develop a simple method for “seamlessly” traversing one body through another moving in an intercepting trajectory. The result is the “blade-thru-slot” (BTS) concept. The application of this concept in a rotary machine leads to blades that orbit circularly inside a chamber and traverse intersecting planar valves through small slots. This approach virtually eliminates compression losses in a mechanically simple way; the slots are not only small in area but also remain “plugged” by the traversing blades while said slots are inside the chamber.
Although the Archer and Pekau engines have lower compression losses than previous toroidal designs, reduced fuel-burning capacity and excessive pumping power requirements are still present. Design limitations do no allow for positive removal of exhaust gases; instead, these remain in the toroidal chamber, between the revolving pistons, and are carried along until they get mixed with the intake charge. Similarly, there is no positive intake of air; an external charger is required to provide fresh air for the compression stroke. Consequences of these limitations are reduced intake of fresh air, excessive amount of exhaust gases in the intake charge, increased pumping losses, and ultimately lower power output.
The BTS engine provides complete removal of exhaust gases from the chamber, and positive intake of air, thus no external charger is required. This comprehensive “breathing” allows the BTS engine to achieve its full power potential.
Generally speaking, the BTS engine has the following advantages over prior art rotary engines: mechanical simplicity, very low friction (as no contact sealing is used), internal lubrication not needed, reduced pumping losses, comprehensive breathing and increased power output.
The above discussion is by extension applicable to other implementations of the BTS machine. Regarding compressors and pumps, main advantages of the BTS machine over reciprocating piston machines are lower friction and wear, no internal lubrication required and reduced power demand. In the case of prior art rotary compressors and pumps, the BTS machine is generally superior in terms of mechanical simplicity, reduced internal friction and no internal lubrication. Regarding pneumatic motors and similar compressed-fluid motors, the general advantages of the BTS machine over conventional and prior art machines are again mechanical simplicity, reduced internal friction, and no internal lubrication.
This invention provides a rotary machine that can be used as a compressor, pump, motor or combustion engine; however, it is mainly intended for use as an internal combustion engine.
The principal object of the present invention is a rotary internal combustion engine that overcomes the reduced performance, high internal friction, excessive wear and low energy efficiency of conventional reciprocating engines. It is a further object of this invention to overcome shortcomings of prior art toroidal engines which generally include sealing problems, insufficient compression, mechanical complexity and excessive pumping power requirements. It is a further object of this invention to provide a mechanically simple engine that can also be constructed with ceramic materials and thus reduced cooling requirements.
The BTS engine can work either as an Otto or Diesel engine (only the first is explained below). The engine consists of a static housing, a rotor(s) with a radial blade(s) on its perimeter, a chamber(s) swept by the blade(s), and a planar valve(s) with slot intersecting the chamber(s). Blades and slot valves move synchronously in a way that blades traverse the valves through the slot. Blades and slots have matching shapes that allow such traversal with negligible loss of working fluid through the slots.
In the double-rotor implementation, a compression rotor and an expansion rotor are mounted on the same main shaft, and share the same slot valve. After traversing the slot valve, the blade on the compression rotor aspires air into the chamber; at the same time, the other side of the blade compresses air against the slot valve and drives it out towards a combustion chamber. An injector on the inlet pipe of the combustion chamber sprays fuel into the air stream. At the end of the compression stroke, the air-fuel mixture in the combustion chamber is ignited by a spark plug. Combustion gases are introduced in the expansion rotor, between the slot valve and the blade. The expanding gases push the blade forward and produce power on the main shaft. The other side of the blade expels from the chamber the exhaust gases left by the previous expansion stroke.
In the single-rotor implementation, the rotor alternatively performs an intake/exhaust stroke and a compression/expansion stroke.
The compression ratio of the double-rotor engine may be regulated by changing the effective volume of the combustion chamber, either manually off operation, or on-demand through a piston-rod mechanism. The above also applies for the single-rotor engine, with the only difference that the volume change is made on the storage chamber.
It is a further object of this invention to provide a compressor/pump with lower friction and wear, and lower power demand than conventional reciprocating compressors and pumps. It is also object of the invention to provide a rotary compressor/pump superior to prior art machines in terms of mechanical simplicity, low internal friction, and no internal lubrication requirements. The BTS compressor/pump is very similar to the compressor side of the double-rotor BTS engine, described above.
It is a further object of this invention to provide a compressed-fluid motor superior to conventional and prior art machines in terms of mechanical simplicity, low internal friction and no internal lubrication requirements. The BTS motor is very similar to the already described expansion side of the BTS double-rotor engine.
FIGS. 13 to 15: Sectional front view of three different stages of the intake/compression stroke (BTS compressor);
FIGS. 17 to 19: Sectional front view of three different stages of the intake/expansion strokes (BTS motor);
FIGS. 38 to 41: Sectional front view of four different stages of the intake/compression and expansion/exhaust strokes (BTS single-rotor engine);
The blade-thru-slot (BTS) rotary machine can be implemented as a compressor, pump, motor or combustion engine. The following description will sequentially describe each of these implementations.
Referring to
A mechanically simpler approach is to use rotary slot valves 5, as shown in
Rotary slot valve 5 is driven by shafts 111 and 12, and pinions 13 to 16; a toothed belt can be used instead of said shafts and pinions. A more sophisticated alternative is to directly drive the rotary slot valve with a special computer-controlled servomotor (not shown).
A synchronization protection for rotor 1 and rotary slot valve 5 may be required in machines (especially combustion engines) subject to high acceleration; this can be achieved by providing small synchronization blades 17 (only one shown in
For an easier understanding, the rest of this description considers the simplest BTS machine implementation, i.e. one blade and one rotary slot valve.
The shape of blade 3 (
As schematically shown in FIGS. 7 to 10, the BTS design allows blade 3 to traverse slot 7 with a negligible loss of working fluid. Said loss is desirable to a certain extent as it provides a fluid cushion between the traversing blade and the slot valve.
Rotor, blade and chamber are manufactured to close tolerance, in order to reduce as practically possible the gaps between the blade and the chamber walls. The small amount of leaks of working fluid through these gaps is largely offset by the important benefits of avoided contact seals, i.e. no wear, no lubrication needed, no heat generated by friction and thus no related energy losses. Moreover, the leaking fluid may help cool the blade edges when it expands through the gaps, following the cooling principle applied in refrigeration systems.
Small grooves 19 can be cut along the edge of blade 3, as shown in
As indicated in
The above mentioned labyrinth seals and grooves are only two possible means to seal the rotor, blade and slot valve against the housing walls. Contact seals may be used instead of or as an aid to said labyrinths and grooves.
FIGS. 13 to 15 schematically show the operation of the BTS compressor or pump. After traversing slot valve 5, advancing blade 3 generates suction on its back side and compression on its front side. Thus, working fluid is aspired through inlet port 27 into sub-chamber 4a; at the same time the fluid in sub-chamber 4b is compressed by the blade against the other side of slot valve 5, and finally pumped out through outlet port 28.
As indicated in
The implementation of the BTS machine as a motor is quite similar to that of the compressor already described. All elements are the same, except for the flap valve, which is not necessary, and a new control valve described below.
The basic operation of the BTS motor is represented in FIGS. 17 to 19. After traversing slot valve 5, blade 3 is pushed forward by the working fluid flowing into sub-chamber 4a through inlet port 27. At the same time, the advancing blade pumps the fluid used by the previous stroke out of sub-chamber 4b through outlet port 28. The flap valve on the outlet port is of course not required; instead, a control valve 30 is needed to regulate the flow and (or) pressure of the fluid entering sub-chamber 4a, according to the power output required from the BTS motor. The design of the control valve depends on the working fluid used to feed the motor, and on the type of controller used for regulating its power output. The rotary control valve presented in
The BTS machine can also be implemented as an internal or external combustion engine. When implemented as internal combustion engine, the BTS machine can follow the conventional Otto or Diesel cycles. For the Diesel cycle, the machine may require closer manufacturing tolerance and/or enhanced sealing for the housing, rotors and slot valves.
For the sake of simplicity, the following description corresponds to an Otto-cycle combustion engine in two basic variants: double-rotor with shared rotary slot valve, and single-rotor. Other variants are possible, e.g. by changing the number and location of the slot valves, and the number of blades and rotors.
Contrary to conventional engines and many alternative designs, in the BTS double-rotor variant the expansion ratio can be increased above the compression ratio, which allows to extract more power from the combustion gases.
In the double-rotor implementation (
As already mentioned, the volume of expansion chamber 31 can be made higher than the volume of compression chamber 4; the purpose is to allow the combustion gases to expand more and thus produce more power than in conventional piston engines.
The axial separation between chambers 4 and 31 provides the delay necessary for the ignition and combustion of the air-fuel mixture; such separation also provides space for slot 7 to recede from compression chamber 4 and emerge in expansion chamber 31.
Combustion chamber 32 can be integrated into the housing, between the rotors (
As indicated in
The operation of the compression side of the engine is presented in FIGS. 23 to 25. After traversing slot valve 5, the advancing blade 3 aspires air into sub-chamber 4a through inlet port 27; at the same time the blade compresses air in sub-chamber 4b and pumps it out through outlet port 33. Flap valve 35 closes when the blade passes by.
In
In
In
The combustion chamber and related components are schematically presented in
The compression ratio of the engine may be regulated by changing the volume of the combustion chamber (
A more sophisticated system, described below, is intended to change the compression ratio on-demand, during the operation of the engine. Piston 54 in
FIGS. 35 to 37 present a closer sectional view of the piston and control rod. Piston 54 has a bore for receiving the end of control rod 55; both the bore and the rod end are manufactured to close tolerance. The rod can slide in or out of the bore within the limits set by chamber 56 and ring clip 57 fixed to the rod. Radial passages 60 and 61 connect to passage 62, drilled along the axis of the rod.
When control rod 55 is pushed inwards (
When the control rod stops, and as a result of the cyclic pressure changes in the combustion chamber, the piston tends to adopt the central position relative to the rod, shown in
Chamber 64 (
A contact seal 66 (
In the single-rotor implementation, the BTS engine consecutively performs an intake/exhaust stroke and a compression/expansion stroke, as schematically presented in FIGS. 38 to 40. Most elements are common to the already explained double-rotor engine, but some modifications and new elements are necessary.
After traversing slot valve 68 (
In
Transfer valve 76 is in fact the same control valve 30 used in the double-rotor engine, thus the rotary design presented in
In the case of inlet/outlet control valves 71 and 74, some modifications to the above mentioned design are required (
The compression ratio of the single-rotor engine may be regulated in the same way as the double-rotor engine (
The power output of BTS Otto-cycle engines may be controlled by regulating the air intake with a conventional throttle valve in the inlet pipe, and by adjusting the fuel injection rate. The management of the entire combustion process—which may also include injection timing, spark timing, and oxygen monitoring in exhaust gases—may be performed by a conventional engine control unit and associated sensors. The control unit's algorithms and lookup tables must of course be specifically developed for each particular family of BTS engines. Additional functions could be built in said engine control unit, such as controlling the servomotors that drive the rotary slot and control valves.
The flow of air intake, and thus the fuel injection rate and power output of BTS internal combustion engines may be increased by attaching a conventional supercharger or turbocharger.
BTS compressors and combustion engines normally will require water and/or air cooling, unless ceramic materials are used. Cooling may be provided through conventional water jackets and air fins on the housing and external combustion/storage chambers, as appropriate.
The above description of BTS rotary machines includes many details that should not be considered as limitations of this invention, but rather as examples of a number of possible variations. Thus, the scope of the present invention should be determined by the appended claims and their legal equivalents, and not by the above described embodiments.