Abstract:
An 8-stroke cycle rotary engine utilizes a pair of master combustion chamber and slave combustion chamber to increase the fuel-efficiency. 8-stroke cycle includes mater intake stroke, slave intake stroke, master compression stroke, slave compression stroke, master expansion stroke, slave expansion stroke, master-to-slave exhaust stroke, and slave exhaust stroke.

Description:
BACKGROUND  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to an 8-stroke cycle rotary engine. More particularly, the present invention relates to an 8-stroke rotary engine that utilizes a pair of master combustion chamber and slave combustion chamber to increase fuel efficiency.  
         [0003]     2. Description of the Related Art  
         [0004]     U.S. Pat. No. 4,159,700 mentioned a “Internal combustion compound engines” wherein a multi-cycle piston engine is provided.  
         [0005]     U.S. Pat. No. 5,056,471 mentioned a “Internal combustion engine with two-stage exhaust” wherein a multi-cycle piston engine with additional piston for harvesting power from exhaust gas is provided.  
         [0006]     U.S. Pat. No. 2,988,065 mentioned a “Rotary internal combustion engine” wherein a four-cycle rotary engine is provided.  
         [0007]     U.S. patent application Ser. No. 10/619,147 mentioned a “Eight-stroke internal combustion engine utilizing a slave cylinder” wherein a eight-stroke piston engine is provided.  
       SUMMARY OF THE INVENTION  
       [0008]     It is well known that four-cycle and other multi-cycle rotary engines produce exhaust gases that contain un-used energy in the form of un-burnt gasses. Many different approaches have been used to both try to capture the un-used energy within these unburned gases and to try to reduce atmospheric emissions caused by inefficient combustion.  
         [0009]     The rotary engines also suffers poor efficiency due to its short power stroke and large heat loss surface area.  
         [0010]     It is a primary objective of the present invention to provide 8-stroke rotary engine which is fuel-efficient, reliable, and environmental-friendly.  
         [0011]     It is also an objective of the present invention to provide an 8-stroke rotary with cooler working temperature to decrease heat loss.  
         [0012]     It is also an objective of the present invention to provide an 8-stroke rotary with multiple power stroke.  
     
    
     BREIF DESCRIPTION OF THE DRAWINGS  
       [0013]     FIGS.  1  to  10  are simplified drawings which show a plurality of successive rotational positions of both master combustion chamber and slave combustion chamber in cross-section perpendicular to the axis of rotation;  
         [0014]      FIG. 11  and  FIG. 12  are simplified structural illustration of the epitrochoids of master combustion chamber and slave combustion chamber and their location relative to each other.  
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0015]     Referring now to  FIG. 11  and  FIG. 12 , the present invention comprises, a master engine housing  11 , a slave engine housing  21 , a master rotor  13  with three apex portions  14 , a slave rotor  23  with three apex portions  24 , an intermediate wall  30 , a primary coordinating channel  31 , a secondary coordinating channel  32 , a master-to-slave exhaust channel  33 , a master intake port  15 , a slave intake port  25 , a slave exhaust port  26 , an eccentric cam  34  connected with an output shaft (not shown), and ignition means  36 .  
         [0016]     The 8-stroke cycle rotary engine is generally similar to the type of rotary engine disclosed in the aforementioned patent, therefore it will not be described in detail here beyond what is necessary to disclose the features of the invention. Details such as sealing means, lubrication means, ventilating means, transmission, ring gears and center gears are omitted in the drawings for clarification purpose.  
         [0017]     A master engine housing  11  having a master combustion chamber  12  of a multi-lobe profile which is basically an epitrochoid and in which the lobes are joined by regions disposed relatively near to the engine axis;  
         [0018]     A slave engine housing  21  having a slave combustion chamber  22  of a multi-lobe profile which is basically an epitrochoid and in which the lobes are joined by regions disposed relatively near to the engine axis;  
         [0019]     The master rotor  13  has a generally triangular profile with three apex portions  14  having sealing cooperation with the inner surface of the master engine housing  11  to form three master working chambers between the master rotor  13  and the master engine housing  11 . These three master working chambers are distinguished form each other by the reference letters  12   a,    12   b,  and  12   c.    
         [0020]     The slave rotor  23  has a generally triangular profile with three apex portions  24  having sealing cooperation with the inner surface of the slave engine housing  21  to form three slave working chambers between the slave rotor  23  and the slave engine housing  21 . These three slave working chambers are distinguished form each other by the reference letters  22   a,    22   b,  and  22   c.    
         [0021]     The working cycle of 8-stroke cycle rotary engine is a 8-stroke cycle operated with both the master rotor  13  and the slave rotor  23 . Referring now to the drawings, and particularly to  FIGS. 1-10 , wherein the master combustion chamber  12  and the slave combustion chamber  22  are shown in successive rotational positions, diagrammatically illustrating each phase position of the master rotor  13  and the slave rotor  23 .  
         [0022]     During the operation of 8-stroke cycle rotary engine, the master working chamber  12   a  co-acts with the slave working chamber  22   a,  the master working chamber  12   b  co-acts with the slave working chamber  22   b,  the master working chamber  12   c  co-acts with the slave working chamber  22   c.  Each master working chamber requires a correspondent slave working chamber to complete its 8-stroke cycle.  
         [0023]     In order to clearly explain in a comprehensive manner, the following description of the 8-stroke cycle operation of 8-stroke cycle rotary engine exclusively refers to the master working chamber  12   a  and the slave working chamber  22   a.  It should be readily understood that the other two pairs of master working chambers and slave working chambers are operating with identical procedures.  
         [0024]      FIG. 1  shows the phase position of the master working chamber  12   a  at the beginning of the first stroke. During the first stroke, the master working chamber  12   a  is located adjacent to the master intake port  15 . As the first stroke commences, the master working chamber  12   a  is open to the master intake port  15  and is fed in with air-fuel mixture until the volume of the master working chamber  12   a  reaches its maximum intake volume, at which point the slave working chamber  12   a  is closed to the slave intake port  25 . At the beginning of the first stroke, the slave working chamber  22   a  is at half-stroke phase position of the preceding 8-stroke cycle.  
         [0025]      FIG. 2  shows the phase position of the slave working chamber  22   a  at the beginning of its second stroke. During the second stroke, the slave working chamber  22   a  is located adjacent to the slave intake port  25 . As the second stroke commences, the slave working chamber  22   a  is open to the slave intake port  25  and is fed in with air until the volume of the slave working chamber  22   a  reaches its maximum intake volume, at which point the slave working chamber  22   a  is closed to the slave intake port  25 . At the beginning of the second stroke, the master working chamber  12   a  is at half-stroke phase position of the first stroke.  
         [0026]      FIG. 3  shows the phase position of the master working chamber  12   a  at the beginning of the third stroke. As the third stroke commences, the air-fuel mixture inside the master working chamber  12   a  is compressed, the volume of the master working chamber  12   a  starts decreasing from a maximum volume condition to a minimum volume condition. At the beginning of the third stroke, the slave working chamber  22   a  is at half-stroke phase position of the second stroke.  
         [0027]      FIG. 4  shows the phase position of the slave working chamber  22   a  at the beginning of the fourth stroke. As the fourth stroke commences, the air inside the slave working chamber  22   a  is compressed, the volume of the slave working chamber  22   a  starts decreasing from a maximum volume condition to a minimum volume condition. At the beginning of the fourth stroke, the master working chamber  12   a  is at half-stroke phase position of the third stroke.  
         [0028]      FIG. 5  shows the phase position of the master working chamber  12   a  at the beginning of the fifth stroke, at which point the master working chamber  12   a  is located adjacent to ignition means  36  on the inner surface of the master housing  31 . When the volume of the master working chamber  12   a  is compressed to a minimum condition, the compressed air-fuel mixture inside the master working chamber  12   a  is ignited with ignition means. The master working chamber  12   a  then goes through the fifth or the first expansion stroke as its volume starts increasing. At the beginning of the fifth stroke, the slave working chamber  22   a  is at half-stroke phase position of the fourth stroke. After the air-fuel mixture inside the master working chamber  11  is ignited, at approximately one-third stroke phase position of the fifth stroke, the master rotor  13  and the slave rotor  23  are so positioned that the primary coordinating channel  31  is open between the master working chamber  12   a  and the slave working chamber  22   a,  thus, the slave working chamber  22   a  starts pushing the air insid the slave working chamber  22   a  into the master working chamber  12   a  to provide more air for expanding and generating the first power stroke to the output shaft  35 .  
         [0029]      FIG. 6  shows the phase position of the slave working chamber  22   a  at the beginning of the sixth stroke, at which point the master working chamber  12   a  is at half-stroke phase position of the fifth stroke, the working medium inside the master working chamber  12   a  is still expanding, while most of the air inside the slave working chamber  22   a  is pushed into the master working chamber  12   a , and the primary coordinating channel  31  is closed. As the sixth stroke commences, the secondary coordinating channel  32  is open between the master working chamber  12   a  and the slave working chamber  22   a,  the working medium then starts to transfer into the slave working chamber  22   a  and to expand thereto. During the sixth stroke, both the master working chamber  12   a  and the slave working chamber  22   a  are expanding and generating the second power stroke to the output shaft  35 .  
         [0030]      FIG. 7  shows the phase position of the master working chamber  12   a  at the beginning of the seventh stroke, the master working chamber  12   a  has expanded to its maximum volume. As the seventh stroke commences, the volume of the master working chamber  12   a  starts decreasing, and the working medium inside the master working chamber  12   a  is being pushed into the slave working chamber  22   a.  At approximately one-third stroke phase position of the seventh stroke, the master-to-slave exhaust channel  33  starts to open between the master working chamber  12   a  and the slave working chamber  22   a , which allows the working medium to exhaust into the slave working chamber  22   a  at more efficient rate. At the beginning of the seventh stroke, the slave working chamber is at the half-stroke phase position of the sixth stroke, as more working medium is pushed into the slave working chamber  22   a,  the slave working chamber  22   a  continues to expand.  
         [0031]      FIG. 8  shows the phase position of the slave working chamber  22   a  at the beginning of the eighth stroke, the slave working chamber  22   a  has expanded to its maximum volume, the secondary coordinating channel  32  is starting to close. During the eighth stroke, all the working medium inside the master working chamber  12   a  is pushed into the slave working chamber  22   a,  and the working medium inside the slave working chamber  22   a  is exhausting through the slave exhaust port  26 . At approximately one-third phase position of the eighth stroke, the secondary coordinating channel  32  is completely close between the master working chamber  12   a  and the slave working chamber  22   a , then the rest of the working medium inside the master working chamber  12   a  is pushed into the slave working chamber  22   a  through the master-to-slave exhaust channel  33 . As shown in  FIG. 9 , at the half-stroke phase position of the eighth stroke, all the working medium inside the master working chamber  12   a  is transferred to the slave working chamber  22   a,  and the master working chamber  12   a  is at the beginning of the first stroke of the next 8-stroke cycle. At the same time, the master-to-slave exhaust channel  33  is closing up, and the working medium inside the slave working chamber  22   a  continues to exhaust through the slave exhaust port  26 . As shown in  FIG. 10 , all the working medium inside the slave working chamber  22   a  has exhausted through the slave exhaust port  26 , thus it completes the 8-stroke cycle. At the same time, the slave working chamber  22   a  is at the beginning of the second stroke of the next 8-stroke cycle, and the following procedures are identical to the 8-stroke cycle described above.  
         [0032]     According to the amount of air required for the first stroke and the second stroke, a charged intake may be essential for 8-stroke cycle rotary engine.  
         [0033]     It should be understood that the invention is not limited to the embodiment described above. Modifications and variations of the embodiment described above will occur to those skilled in the art without leaving the spirit and scoop of the present invention. The scope of the invention is defined with reference to the following claims.