Patent Publication Number: US-7584726-B2

Title: Two-stroke opposite radial rotary-piston engine

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims the benefit according to 35 U.S.C. 119(e) of a U.S. provisional patent application Ser. No. 60/881,208, filed on Jan. 19, 2007, the disclosure of which is incorporated herein in its entirety by reference. 

   FIELD OF THE INVENTION 
   The invention relates to opposite radial rotary-piston engines that can be utilized in ground vehicles, water vehicles, aircraft, in combinations with generators, etc. 
   BACKGROUND OF THE INVENTION 
   In the prior art there are known several constructions of centrifugal-piston or rotary-piston engines (herein further called ORPE), which are intended to eliminate certain disadvantages of conventional piston engines. E.g., such constructions are described in DE3907307, U.S. Pat. No. 6,279,518, WO2005098202, RU2143572, JP7113452. The latter, for instance, has the purpose “to suppress the side pressure applied to a piston, improve efficiency, reduce vibration and drastically reduce dimension and weight, by revolving a cam on the inner wall of an ellipse without using a crank, in reciprocating motion.” The other above indicated constructions typically have similar purposes. 
   DE3907307 discloses a four-stroke engine wherein a cylinder block revolves inside a rotor, which is complicated, has a small resource of the valve system, and a des-balance with the revolving system including movable parts. 
   U.S. Pat. No. 6,279,518 discloses a four-stroke engine having a valve system and a conically shaped rotor.  FIG. 7  shows a conical rotor with an elliptical groove, and a series of pistons followers inside the groove. It is a complicated unit with substantial friction losses, which has a limited operation resource for its loaded parts. The construction does not eliminate the side forces exerted by the piston upon the cylinder walls. 
   RU 2143572 discloses a four-stroke engine, wherein the cylinder block revolves at an elliptical trajectory, and the inlet/outlet system includes a rotatable valve. The construction is complicated and difficult to balance (which is admitted by its author). The piston acts via its rod and a sliding bearing upon an elliptical housing. The place of contact with the housing experiences high friction and heating, and thus will have a short operation resource. 
   From the inventors point of view, a more advanced design of OPRE is presented in U.S. Pat. No. 6,161,508. It describes “a radial-piston engine of rotary type of the kind having a valve system comprising apertured disc rings arranged in intersliding relationship, one of said rings being stationary while the other one is arranged to take part in the rotary motion of the rotor. The valve opening relationship is determined by the manual angular positions of the discs. In accordance with the invention, filed injection takes place via an injection nozzle positioned in the stationary disc. The valve ring is formed with a through opening which in response to the position assumed my the rotor at the moment of fuel ignition forms an open communication means between the injection nozzle and the combustion chamber.” 
   That engine however has also certain drawbacks and limitations. It is built as a four-stroke engine having a cylinder block revolving around and impelling a rotor. Reaction forces produced in support bearings are very significant that leads to a short operation resource period. It uses an inlet/outlet system based on a rotatable sliding valve. This necessitates the use of complicated sealing means that, as a rule, have very limited operation resource (typically 100 hours maximum). The rotating cylinder block with linearly reciprocating pistons is very hard to balance, and thusly will cause intensive destructive vibrations. These problems are successfully resolved in the present invention. 
   BRIEF DESCRIPTION OF THE INVENTION 
   The inventive ORPE employs the mentioned non-typical form of conversion of the spinning motion of a rotor into a progressive linear stroke of a piston, and vice versa. This constructive solution provides for substantial absorption of side forces exerted by the piston onto engine cylinder&#39;s walls and vice-versa, and for an essential improvement of the weight and fuel consumption/power output ratios, demonstrating useful advantages over all presently utilized engines known to the inventors, including the Wankel rotor engine. 
   The most important advantages of the invention are a simple design, low mass, long operation resource (supposedly over 1,000,000 km), low fuel consumption and high power torque, low level of pollutions (environmentally-friendly). 
   The engine&#39;s weight (without attached devices) is estimated about 30 kg. It has a displacement of 500 cc, and should deliver a 250 horse-power. In a more powerful version, the engine&#39;s own weight is estimated 65 kg (without attached devices), having a displacement of 1000 cc and should deliver a 500 horse-power. 
   The engines as described in the invention may be employed in different applications, such as for joint operation with generators, water and surface vehicles motors, for aircraft motors, and capable to successfully compete with traditional internal combustion engines. 
   The design solutions embodied in the engine&#39;s lubrication and cooling systems allow exploiting the engine at 12000-15000 rpm, which can provide for an efficient motor sports application. The construction described in the present disclosure allows developing and manufacturing engines fueled by gasoline or natural gas, as well as diesel type engines employing the inventive principles. 
   The inventive ORPE has a rotor&#39;s operation surface formed by a closed symmetrical ellipse-type line 
                 x   2       a   2       +       y   2       b   2         =   1         
or by a Cassini line that can be described by a formula: (x 2 +y 2 )−2c 2 (x 2 −y 2 )=a 4 −c 4 , wherein ‘x’ and ‘y’ are the two-dimensional coordinates, and ‘a’ and ‘b’ are predetermined coefficients.
 
   The present disclosure describes a two-stroke opposite rotary-piston engine that comprises a cylinder block including a sleeve and two pistons slidely disposed therein and oppositely movable, which pistons are forming a common combustion chamber situated between their heads, and forming a first gap with sleeve&#39;s sidewalls; a rotor having a surface formed by an ellipse or Cassini line; traverses attached to the pistons; rollers attached to the traverses and springly depressed against the rotor; oil tubes with end bushings; oil supply and withdraw means; two plungers disposed in each tube forming a second gap with the tube&#39;s sidewalls, essentially less than the first gap. The plungers are attached to the traverses and oppositely movable, also including through throttling channels, outward surfaces forming external spaces with the bushings, and inward surfaces forming an internal space with the tube sidewalls, which internal space communicates with the oil supply means and the oil withdraw means. Engine&#39;s oil drain means communicate the external spaces with the oil supply means. The engine absorbs side and inertial forces, is more efficient and clean. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1   a  illustrates a general frontal view of the assembled engine, according to a preferred embodiment of the present invention. 
       FIG. 1   b  illustrates a side sectional view of the engine in the uppermost “dead point” of the rotor and shows base units and details of the engine&#39;s construction, according to a preferred embodiment of the present invention. 
       FIG. 2   a  illustrates a general frontal view of the assembled engine, according to a preferred embodiment of the present invention. 
       FIG. 2   b  illustrates a side sectional view of the engine in the lowermost “dead point” of the rotor and shows base units and parts of the engine&#39;s construction, according to a preferred embodiment of the present invention. 
       FIG. 3   a  illustrates a general side view of the assembled engine, according to a preferred embodiment of the present invention. 
       FIG. 3   b  illustrates a frontal sectional view of the engine, showing the design of the plungers, plungers&#39; tubes, and other base units and parts of the engine&#39;s construction, according to a preferred embodiment of the present invention. 
       FIG. 4   a  illustrates a sectional view of the plungers&#39; tubes and plungers at the lowermost dead-point of the engine, according to a preferred embodiment of the present invention. 
       FIG. 4   b  illustrates a sectional view of the plungers&#39; tubes and plungers at the uppermost dead-point of the engine, according to a preferred embodiment of the present invention. 
   

   Similar reference numerals in the drawings generally refer to the same or similar elements in different figures. A newly introduced numeral in the description is enclosed into parentheses. 
   DESCRIPTION OF A PREFERRED INVENTIVE EMBODIMENT 
   While the invention may be susceptible to embodiment in different forms, there is shown in the drawings, and will be described in detail herein, a specific embodiment of the present invention, with the understanding that the present disclosure is to be considered an exemplification of the principles of the invention, and is not intended to limit the invention to that as illustrated and described herein. 
   An embodiment of the inventive engine, fueled by gasoline, is illustrated in  FIGS. 1   a ,  1   b ,  2   a ,  2   b ,  3   a , and  3   b . The engine comprises a stationary cylinder block ( 1 ) fixedly mounted, e.g. on a vehicle; a cylindrically shaped sleeve ( 2 ) mounted to the block  1 ; two oppositely movable cylindrical pistons ( 3 ) slidely snug-fitting in the sleeve  2 . In a preferred embodiment, a first gap between the piston  3  and the sidewalls of the sleeve  2  is made in the size of about 50 micrometers. 
   The opposite pistons  3  each includes a bottom head. The surfaces of the bottom heads and a portion of sidewalls of the sleeve  2  (between the bottom heads) collectively form a common work chamber and a common combustion chamber. 
   The block  1  includes a supporting bearing (preferably ball-bearing). A spark-plug ( 16 ) and an injector ( 17 ) are installed in the block  1 . 
   The block  1  and sleeve  2  include an inlet port ( 12 ) and outlet port ( 13 ), preferably milled out therein, to provide air supply and combustion products exhaust correspondingly. The air supply is introduced from a supercharging air compressor ( 14 ), in this embodiment mechanically driven by the engine. In other embodiments, it may be driven by other means. The compressor  14  is connected to the inlet port  12 . 
   The engine comprises two fork-shaped traverses ( 4 ), each aforesaid traverse  4  is coupled with one of the pistons  3  by means of lock-nuts with a female threading screwable on a male threading of the traverse. The threading connection allows adjusting the compression ratio within a range of from 8 to 11 during the assembly process. 
   The engine comprises supporting rollers ( 5 ) to transmit forces from the pistons  3  and traverses  4 , which rollers  5  are mounted to the traverses  4  by means of pins (not shown). 
   The engine comprises a stationary housing ( 11 ) fixedly mounted, e.g. on a vehicle. The housing  11  includes a supporting bearing ( 10 ) (preferably, a ball bearing). In  FIGS. 1   a ,  1   b ,  2   a ,  2   b , the housing  11  is conventionally shown vertically positioned, though in reality it is typically positioned horizontally. The housing  11  is filled up with oil for lubrication and other purposes as described further in the disclosure. 
   The engine comprises a rotor ( 8 ), having a closed inner operation surface formed by a predeterminedly curved line, for example, a closed symmetrical ellipse-type line or Cassini line mentioned hereinabove. The rotor  8  is mounted on the supporting bearing installed within the housing  11  and on the supporting bearing installed within the cylinder block  1 . 
   The engine comprises a rotatable power takeoff shaft ( 9 ) mounted at least on the supporting bearing  10 . The shaft  9  is fixed to the rotor  8 . The rotation torque of the rotor  8  is transmitted to the shaft  9  and can be further conveyed to a transmission. 
   The traverses  4  interact with springs ( 7 ), which springs depress the supporting rollers  5  against the rotor  8 , providing for a mild unstressed engaging at engine&#39;s start. 
   As depicted in  FIGS. 4   a  and  4   b , the engine comprises an oil supply conduit ( 19 ) of low pressure with a reverse valve (not shown) mounted therein, and an oil withdraw conduit ( 20 ) of high pressure with a reverse valve and a pressure-reduction valve (both not shown) mounted therein. The conduits  19  and  20  are connected to the housing  11 , and used at least for lubrication of the engine and other purposes disclosed below. 
   The engine comprises an oil pump, shown in  FIGS. 3   b ,  4   a ,  4   b  including two sections, each comprising a tube ( 15 ) and two opposite plungers ( 6 ) slidely snug-fitting within each tube  15 . Each plunger  6  has a piston portion and a rod portion. The rod portions of plungers  6  are attached to the traverses  4  (as shown in  FIG. 3   b ) by means of pins (not shown). In a preferred embodiment, a second gap between the pump tube  15  and the plungers  6  is made in the size of about 2-4 micrometers, i.e. essentially less than the first gap. 
   The tube  15  has an oil suction inlet connected to the oil supply conduit  19  and an oil discharge outlet connected to the oil withdraw conduit  20 , which inlet and outlet are drilled in the pump tubes, as depicted in  FIGS. 4   a  and  4   b.    
   The oil pump includes guide bushings ( 18 ) coupled to both the ends of each tube  15 , as shown in  FIG. 4   a . The bushings  18  serve to close the tube  15  at its ends, and to guide the linear movement of the rod portion of plunger  6 . 
     FIGS. 4   a  and  4   b  show: inward head surfaces (D) of the piston portions of plungers  6  inside the tube  15 , so that the two surfaces D are facing each other; outward surfaces (C) of the piston portions of plungers  6  facing the bushings  18 ; an internal space (A) formed between the inward surfaces D and the inner sidewalls of the tube  15 ; external spaces (B) formed between the outward surfaces C, the rod portion sidewalls and the inner sidewalls of the bushings  18 . 
   The oil pump includes two oil drain pipes ( 21 ), each communicating the external spaces B with the oil suction inlet ( FIGS. 4   a  and  4   b ). 
   Each plunger  6  includes a through throttling channel ( 22 ) drilled preferably along the longitudinal axe of plunger  6  with a predeterminedly small diameter to provide necessary resistance to the oil cross-flow therethrough. The purpose of making the channel  22  is to prevent the device from destroying by a hydro-impact during its operation. The channel  22  has a perpendicular through portion capable to communicate the channel  22  with the space B. 
   The plungers  6  perform several important functions in the engine. A first function is the pumping of oil, which is a regular lubrication function common for an oil pump. 
   A second function of the plungers  6  is the absorption of side forces caused by the interaction between the rollers  5  and the rotor  8 . Since the gap between the sleeve  2  and the piston  3  is essentially greater than the gap between the pump tube  15  and the plunger  6  (the size of 50 micrometers against the size of from 2 micrometers to 4 micrometers respectively), the plunger  6  absorbs the aforesaid side forces. 
   A third function of the plungers  6  is the providing for parallel movement of the pistons  3  within the sleeve  2  due to the absorption of aforesaid side forces. 
   A fourth function of the plungers  6  is the providing for a predetermined volume of the combustion chamber and for absorption of inertial forces developed by the pistons  3  and substantially exerted onto the rotor  8 . This is achieved due to operation of the plungers  6  as “hydro-lock” valves in a hydro-system in the uppermost and lowermost dead points of the piston&#39;s traveling. 
   OPERATION OF THE PREFERRED INVENTIVE EMBODIMENT 
     FIG. 1   b  illustrates the positions of the pistons  3  with the traverses  4  situated in the uppermost dead-point wherein a common combustion chamber is formed by the pistons&#39; heads and a respective portion of the sleeve&#39;s inner sidewalls (the uppermost dead-point corresponds to the minimal volume of the common combustion chamber). In the positions, a spark is produced by the spark-plug  16 , igniting the fuel-air mixture in the combustion chamber that moves the pistons  3  with the traverses  4  in the opposite directions. The rollers  5  depress the rotor&#39;s inner curved operation surface, impelling the rotor  8  to spin, which rotates the takeoff shaft  9 . 
   During the further traveling of the pistons  3  up to a 90 degrees turn of the rotor  8  (the lowermost dead-point corresponds to the maximal volume of the common combustion chamber, depicted in  FIG. 2   b ), the inlet port  12  and outlet port  13  are opened that provides for blowing the combustion products out and filling up the cylinder&#39;s sleeve  2  with a portion of fresh air supplied by the compressor  14 . 
   During the next 90 degrees turn (not illustrated), the rotor  8  spins due to inertia, pushing the pistons  3  via the rollers  5  and traverses  4 , which results in the movement of pistons towards each other up to the uppermost dead-point, compressing the air in the sleeve  2 . After the pistons  5  pass the inlet port  12  and the outlet port  13 , a portion of fuel is injected into the combustion chamber through the injector  17 . The mixture of fuel and air is intensely intermingled in the chamber up to the uppermost dead-point position of the pistons  3  (shown in  FIG. 1   b ). 
   When a 180 degree turn of the rotor  8  is completed, the next spark is produced in the combustion chamber and the above-described two-stroke cycle is repeated. Therefore, the two-stroke cycle is performed during a 180-degree turn of the takeoff shaft, whereas, in a traditional piston internal combustion engine and all the aforementioned prior art engines, a two-stroke cycle is performed during a 360 degree turn. This doubles the frequency of the engine&#39;s cycles, resulting in an increase of its power. 
   Parallel processes occur in the oil tubes  15  and plungers  6  during operation of the engine. At the time when the pistons  3  travel to the lowermost dead-point, oil is sucked from the housing  11  into the supply conduit  19 , and, via the oil suction inlet, into the expanding space A of the tube  15  ( FIG. 4   a ). Simultaneously, oil is ejected from the space B into the drain pipes  21  by means of the inward surfaces C. 
   After the surfaces C pass the drain pipes  21 , they will be closed by the piston portions of the plungers  6 , and the oil left in the spaces B will prevent the further movement of the plungers  6  and, thusly, prevent the movement of the pistons  3  associated with the plungers  6  through the traverses  4 . This situation is known as a “hydro-lock” in the space B, and it causes the lowermost dead-point of the engine. The aforementioned throttling channels  22  prevent the plungers and other mechanisms associated therewith from destroying by a hydro-impact taking place at the abrupt stop of the plungers  6 , caused by the hydro-lock. 
   During the reverse movement of the plungers  6 , the space A is contracting ( FIG. 4   b ) and oil is ejected therefrom by the surfaces D into the withdraw conduit  20  via the oil discharge outlet. After the surface D passes the oil suction inlet, the oil left in the space A is confined and forms a hydro-lock in the space A, which determines the position of the uppermost dead-point of the engine. 
   Due to the absence of a crank-shaft, the side forces taking place in the crank-shaft and inertial loads caused by the crank-shaft rotation are substantially eliminated. This reduces friction losses by about 50%, and accordingly lessens the fuel consumption and saves a fuel amount necessary to cover the friction losses. The fuel efficiency of the engine leads to reduction of pollutions that makes the engine environmentally friendly.