Abstract:
A hybrid engine comprises a housing and at least one rotor. The engine employs tongue and groove system to generate rotational movement. As the rotor pivots, reciprocating tongues slide into and out of the grooves. In pneumatic mode, introduction of compressed air forwardly into the grooves drives the rotor. Meanwhile, the air exhaust is cleared from the grooves rearwardly. In internal combustion mode, compression and air intake strokes start and end at the same time in a groove. Combustion and exhaust strokes occur simultaneously in the next groove arriving at the combustion chamber.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Not Applicable 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates generally to hybrid pneumatic-combustion engines. This device also relates to rotary internal combustion engines. 
         [0004]    2. Description of the Related Art 
         [0005]    Similar to reciprocating piston engines, rotary engines are internal combustion engines that employ a rotary design to convert the energy of expanding combustion gases into rotating motion. Examples of rotary engines are disclosed in U.S. Pat. No. 3,306,269, 3,793,998, 3,855,977, 4,066,044, 4,072,132, 4,401,070, 5,261,365, 5,551,853, 6,164,263, 6,899,075B2, and 2013/0228150A1. The most well-known application for rotary engine is the Wankel engine (U.S. Pat. No. 2,988,065) which was produced for Mazda automobiles. 
         [0006]    It is expected that internal combustion engines to be the main power source to propel vehicles for many years to come. It is well known that the internal combustion engines have low fuel efficiency, and are the major source of air pollution. In this regard, and in order to improve the fuel efficiency, hybrids and electric vehicles have gotten many attentions; see U.S. Pat. No. 5,191,766, 5,343,970A, and 8,365,699B2. However, the drawbacks of the hybrid electric-combustion and electric vehicles are high battery costs, weight, and maintenance requirements. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    Accordingly, the primary object of the present invention is to provide a hybrid engine which can operate alternatively as a pneumatic motor and as an internal combustion engine. Similar to many other hybrid engines, this invention employs an electronic management system that regulates the operating modes based on the current driving needs, and in order to optimize energy efficiency. The present engine runs in the internal combustion mode when more power is required, and in the pneumatic mode when less power is needed. 
         [0008]    Another object of this invention is to provide a rotary engine with a novel configuration which is simple to design, more efficient, and easy to make. In many combustion rotary engines such as Wankel engine, the gas expansion caused by combustion, especially during starting, could kick the engine to run simultaneously in both standard and reverse rotations, and consequently reduce the efficiency. While, the expansion of gases in this invention drives the rotor only in one direction, and kick back is not possible, 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a perspective exploded view of the hybrid rotary engine according to an embodiment of the invention. 
           [0010]      FIG. 2  is a transverse sectional view of the rotor cut through the center of the pressure grooves and perpendicular to the central shaft shown in  FIG. 1 . 
           [0011]      FIG. 3  is a transverse sectional view of the assembled engine cut through the center of the intake and exhaust passages, and perpendicular to the central shaft which is shown in  FIG. 1 . 
           [0012]      FIGS. 4 to 6  are transverse sectional views of the engine, similar to  FIG. 3 , showing different stages of the engine&#39;s working cycle. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0013]    As shown in  FIG. 1 , rotary engine  10  has the following principal components: (1) a housing  11  which has a cylindrical inner surface  12 , and is for housing other components, (2) an inner body or rotor  13  which is rotatable within the housing  11  cavity, and is supported by a central shaft  14 , (3) two plates  15  for enclosing both sides of the housing  11  (only one plate has been shown in  FIG. 1 ). Each plate  15  has a bore  16  through which the central shaft  14  projects outward, and is supported by means of a bearing  17  on each plate  15 . 
         [0014]    Referring to  FIG. 1 , the rotor  13  has one or a plurality of semi-annular grooves  18  which are open toward the inner surface of the housing  12 . These grooves  18  are comparable to the cylinders on the conventional engines, and will be called pressure grooves  18  hereafter. The pressure grooves  18  have elongated shapes, and are perpendicular to the axis of rotation. 
         [0015]    For small engines, the rotor  13  is made of one cylindrical-shaped piece which is mounted on central shaft  14 . The diameter of the rotor  13  is approximately equal to the internal diameter of the housing  11 . For larger engines, the rotor  13  is made of a plurality of pie-shaped elements  19 , as shown in  FIG. 2 . In this case, the rotor&#39;s elements  19  have holes  20  on their inner sides in such that the holes  20  are facing perpendicularly to the central shaft  14 . Through their holes  20 , the rotor&#39;s elements  19  are slidably mounted on bars  21  radiating from the central shaft  14 . Outer surfaces of the rotor&#39;s elements  22  are normally held in sealing engagement with the inner surface of the housing  12  by centrifugal force when the engine is running. In order to augment the seal between the inner surface of the housing  12  and the outer surface of the rotor&#39;s elements  22 , springs  23  are mounted around the bars  21  between the central shaft  14  and the rotor&#39;s elements  19 . The springs  23  push the rotor&#39;s elements  19  against the central shaft  14  toward the inner surface of the housing  12 . Alternatively and instead of the springs  23 , hydraulic or pneumatic pressure can be employed to create a more stable seal between the outer surface of the rotor&#39;s elements  22  and the inner surface of the housing  12 , using a pressure sensor (not shown). Liquid lubrication is applied between the outer surface of the rotor  22  and the inner surface of the housing  12  to reduce friction and wear. For simplicity and as an example of small engines, the rotor  13  is shown as one piece in  FIGS. 3-6 . 
         [0016]    Referring again to  FIG. 1 , a cavity, located at the peripheral inner surface of the housing, acts as the combustion chamber  24 . The combustion chamber  24  has normally a cuboid shape but it could have other shapes as well. In the illustrated embodiment of  FIGS. 3-6 , two combustion chambers  24  on the housing  11  have been shown but that number is understood as not being intended as a limitation of the invention. Spark plugs  25  are mounted on the housing  11 , and projected into the combustion chambers  24 . The engine  10  also has fuel injectors  26  which extend through the housing  11  and into the combustion chamber  24 . The fuel injectors  26  are employed to inject a combustible fuel in the combustion chamber  24  at the proper time in relation to the working cycle. 
         [0017]    The housing  11  has a plurality of slots which extend completely through the housing  11 , and perpendicularly and radially to the central shaft  14 . There are one slot  27  at the front side, and one slot  28  at the rear side of each combustion chamber  24 . Henceforward, the terms “front” and “rear” are used with reference to the direction of rotation. As seen in FIGS.  1  and  3 - 6 , the rotor  13  is driven in a clockwise direction, that is, in the direction of arrows. Each slot  27  and  28  is shaped to slidably receive a tongue in sealing contact. The tongues that go into the front slots  27  and rear slots  28  will be respectively called compression tongues  29  and combustion tongues  30 . The tongues  29  and  30  are equivalent to the pistons on the reciprocal engines. When the engine  10  is running, the tongues  29  and  30  reciprocate within their respective slots  27  and  28 , and into the pressure grooves  18 . Tips of the tongues  29  and  30 , and wall of the pressure grooves  18  have the same shapes, which are normally U shape but other shapes such as V or rectangular could be used as well. When moving into and along the pressure grooves  18 , the tips and sides of the tongues  29  and  30  form seals with the wall of the pressure grooves  18 . 
         [0018]    As viewed in  FIGS. 3-8 , return springs  31  and  32  supported by upper body of the tongues  33  and  34  acts against the housing  11  to urge the tongues  29  and  30  out of their respective slots  27  and  28  in the housing body  11 , and away from the rotor  13 . Camshafts  35  are employed for timely operation of the tongues  29  and  30 . The camshafts  35  are movably connected to the central shaft  14  by timing gears (not shown) and chain assembly (not shown). When cam lobes  36  and  37  engage the upper body of the tongues  33  and  34 , the tongues  29  and  30  are pushed into their respective slots  27  and  28  toward the rotor  13 , and into the pressure grooves  18  against the action of their return springs  31  and  32 . As the cam lobes  36  and  37  rotate further, the return springs  31  and  32  act to pull back the tongues  29  and  30  into their resting positions in their respective slots  27  and  28 . For maximum efficiency of the engine  10 , it is understood that the cam lobes  36  and  37  should be shaped with considerable accuracy to keep the tip of the tongues  29  and  30  in sealing contact with the wall of pressure grooves  18  while the rotor  13  is running. Instead of camshaft system, any other mechanical design for movement of the tongues  29  and  30  would be equally satisfactory. 
         [0019]    Referring to  FIG. 3 , the housing  11  also includes a plurality of passages. Air intake passages  38  are located adjacent to and at the front of the compression slots  27 . Fuel exhaust passages  39  are disposed next to and at the rear of the combustion slots  28 . Compressed air exhaust passages  40  are placed at the rear of the compression slots  27 , and into the combustion chambers  24 . Poppet valves are used to control the passage of the gases into and out of the engine  10 . Camshafts are employed to operate the poppet valves at proper cycle. Since this operation is very well known, the valves operating camshaft and poppet valves are omitted from the drawings for clarity. Alternatively and instead of the camshafts, hydraulic or pneumatic actuators can also be deployed to regulate the gases flow through the intake and exhaust passages. 
         [0020]    The operation of the engine  10  is best understood with reference to  FIGS. 4-6 . The engine  10  is normally started by imparting initial rotation to the central shaft  14  using a suitable starter motor (not shown). When operating in the combustion mode, the engine  10  uses the pressure created by burning fuel to run, similar to piston engines. The engine  10  of the present invention is a four-stroke engine, which each stroke has two phases of operation; intake/compression and combustion/exhaust. Every other pressure groove  18  that passes a combustion chamber  24  serves for either the intake/compression phase or combustion/exhaust phase while the phases occur one after another at each combustion chamber  24 . As soon as the tongues  29  and  30  are pushed into the pressure grooves  18  by their corresponding cam lobes  36  and  37 , the pressure grooves  18  are divided into two spaces; front and rear spaces. When the compression tongues  29  enter into the pressure grooves  18 , the intake and compression respectively happen in the front and rear spaces of the compression tongues  29 . When the combustion tongues  30  enter into the pressure grooves  18 , the combustion and exhaust respectively occur in the front and rear spaces of the combustion tongues  30 . 
         [0021]    Referring to  FIG. 4 , as the compression tongues  29  go into the pressure grooves  18 , air is received into the front space of the pressure grooves  18  through the opened air intake passages  38 . The air is kept in the pressure grooves  18  for the next stroke. At the same time as the pressure grooves  18  continue to move forward, and pass by the compression tongues  29 , the air trapped in the pressure grooves  18  at the previous stroke is compressed and guided to the combustion chambers  24 . The compression is due to decreasing volume of the rear space of the pressure grooves  18  when the pressure grooves  18  are moving forward. At the end of intake/compression phase, the compression tongues  29  are placed at its resting position in the housing  11 . 
         [0022]    As shown in  FIG. 5 , when the next pressure grooves  18  reach the combustion chambers  24 , this time the combustion tongues  30  are pushed into the pressure grooves  18  by their corresponding cam lobes  37 . The fuel is then injected by the fuel injectors  26  in the combustion chambers  24 , and the air/fuel mixture is ignited by the spark plugs  25  to provide the power stroke at the front of the combustion tongues  30 . At this moment, the volumes of the front spaces of the combustion tongues  30  are close to their minimum. The pressure of combustion forces the pressure grooves  18  to move in the direction that makes the front spaces of the pressure grooves  18  grow in volume. The combustion gases continue to expand, moving the rotor  13 , and creating power, until the pressure grooves  18  completely pass the combustion tongues  30 . In the meantime that the combustion tongues  30  are inside and moving along the pressure grooves  18 , the fuel exhaust passages  39  are open, and the combustion tongues  30  rearwardly push the exhaust gases produced at the previous stroke, out of the pressure grooves  18 . It should be noted that the compressed air exhaust passages  40  are closed at all time during the combustion mode. 
         [0023]    It is worth noting that in the present invention, the number of combustion strokes for every rotation of the central shaft  14  can be calculated using the following equation; S=(C*G)/2, where C is the number of combustion chambers  24  on the housing  11 , G is the number of pressure grooves  18  on the rotor  13 , and S is equal to the number of power stroke per central shaft  14  revolution. Therefore, an engine  10  with one combustion chamber  24  and one pressure groove  18  completes one combustion stroke for every two rotations of the central shaft  14 . While, an engine  10  with two combustion chambers  24  and two pressure grooves  18 , as shown in the drawings, has two power strokes per one revolution of the central shaft  14 . 
         [0024]    When operating in the pneumatic mode, the air intake passages  38  admit the introduction of compressed air into the engine  10 . As seen in  FIG. 6 , as soon as the compression tongues  29  enter into the pressure grooves  18 , compressed air is injected into the front space of the pressure grooves  18  through the opened air intake passages  38 . At this point, the volumes of the front spaces are minimum. Expansion of the compressed air forces the pressure grooves  18  to move in the direction that makes the volumes of the front spaces to increase, therefore, pushes the pressure grooves  18  forward, and drives the rotor  13 . The expansion of the compressed air can continue until the pressure grooves  18  completely pass the compression tongues  29 . Meanwhile, the compressed air exhaust passages  40  are open, and moving of the compression tongues  29  along the pressure grooves  18  rearwardly clear the exhaust gases through the compressed exhaust passages  40 . The compressed air exhaust passages  40  are open at all time when the engine  10  runs in the pneumatic mode.