Patent Publication Number: US-9896990-B2

Title: Internal combustion engine with port communication

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a division of U.S. application Ser. No. 14/887,611 filed Oct. 20, 2015, which is a continuation of U.S. application Ser. No. 13/799,965 filed Mar. 13, 2013, the entire contents of both of which are incorporated by reference herein. 
    
    
     TECHNICAL FIELD 
     The application relates generally to internal combustion engines and, more particularly, to such engines operating under the principle of the Miller cycle. 
     BACKGROUND OF THE ART 
     Internal combustion engines operating under the principle of the Miller cycle usually have an open inlet port during the beginning of the compression phase of the combustion chamber(s). In a reciprocating engine, the Miller cycle may be obtained through timing of the opening of the inlet valve. In a rotary engine such as a Wankel engine, the Miller cycle may be obtained through proper positioning of the inlet port. The Miller cycle engine usually has a volumetric compression ratio lower than its volumetric expansion ratio. 
     Typically, the Miller cycle engine is used with a turbocharger to prevent loss of air during the beginning of the compression phase and to increase the pressure compression ratio. However, during the beginning of the compression phase when the inlet port is open, compression must be typically performed against the pressure of the turbocharger, which usually creates pressure losses. 
     SUMMARY 
     In one aspect, there is provided an internal combustion engine comprising: at least two rotatable bodies; an outer body defining a respective internal cavity for each of the bodies, each of the bodies being sealingly and rotationally received within the respective internal cavity to each define at least one combustion chamber of variable volume undergoing a cycle defining successive phases of intake, compression, combustion and exhaust; at least one inlet port for each respective internal cavity, the at least one inlet port being in fluid communication with each of the at least one combustion chamber of the respective internal cavity at least during the intake phase thereof and a beginning portion of the compression phase thereof; at least one exhaust port for each respective internal cavity, the at least one exhaust port being in fluid communication with each of the at least one combustion chamber of the respective internal cavity during the exhaust phase thereof; a rotatable shaft, the bodies being drivingly engaged to the shaft in an angularly offset manner with the beginning portion of the compression phase of the at least one combustion chamber defined by each of the bodies being simultaneous with at least a beginning of the intake phase of the at least one combustion chamber defined by a different one of the bodies; a plenum for receiving pressurized air; and a respective conduit providing a fluid communication between the at least one inlet port of the respective internal cavity of each of the bodies and the at least one inlet port of the respective internal cavity of the different one of the bodies, each respective conduit being in fluid communication with the plenum. 
     In another aspect, there is provided an engine comprising: a turbocharger having a compressor; a rotary internal combustion engine having: at least two rotors, an outer body defining: a respective internal cavity for each of the rotors, each of the rotors being sealingly and rotationally received within the respective internal cavity to define a plurality of combustion chambers of variable volume each undergoing a cycle defining successive phases of intake, compression, combustion and exhaust, a primary inlet port for each respective internal cavity, the primary inlet port being in fluid communication with each of the at least one combustion chamber of the respective internal cavity during the intake phase thereof and a beginning portion of the compression phase thereof; a secondary inlet port for each respective internal cavity, the secondary inlet port being in fluid communication with each of the at least one combustion chamber of the respective internal cavity during a secondary portion of the cycle thereof extending at most over a beginning of the intake phase and an end of the exhaust phase, and an exhaust port for each respective internal cavity, the exhaust port being in fluid communication with each of the combustion chambers of the respective internal cavity during the exhaust phase thereof; a rotatable shaft, the rotors being drivingly engaged to the shaft in an angularly offset manner with the beginning portion of the compression phase of the at least one combustion chamber defined by each of the rotors being simultaneous with at least part of the secondary portion of the cycle of the combustion chambers defined by a different one of the rotors; a plenum in fluid communication with the compressor; and a respective conduit providing a fluid communication between the primary inlet port of the respective internal cavity of each of the rotors and the secondary inlet port of the respective internal cavity of the different one of the rotors, each respective conduit being in fluid communication with the plenum. 
     In a further aspect, there is provided a method of feeding air to an internal combustion engine having at least first and second internal cavities each sealingly and rotationally receiving a respective rotor therewithin, each of the internal cavities having a primary inlet port and a secondary inlet port in fluid communication therewith, the method comprising: feeding compressed air to a combustion chamber of the first cavity through the primary inlet port thereof while increasing a volume of the combustion chamber until a maximum volume thereof is reached; while reducing a volume of the combustion chamber from the maximum volume and at least in part while increasing a volume of a combustion chamber of the second cavity, feeding compressed air from the combustion chamber of the first cavity through the primary inlet port thereof into the combustion chamber of the second cavity through the secondary inlet port thereof; closing a communication between the primary inlet port and the combustion chamber of the first cavity and further reducing the volume of the combustion chamber of the first cavity until a minimum volume thereof is reached; and feeding compressed air to the combustion chamber of the second cavity through the primary inlet port thereof while increasing the volume of the combustion chamber of the second cavity until a maximum volume thereof is reached. 
     In a further aspect, there is provided a method of feeding air to an internal combustion engine having at least first and second internal cavities, the first internal cavity defining at least a first combustion chamber, the second internal cavity defining at least a second combustion chamber, the first and second combustion chambers each having a variable volume and undergoing a cycle defining successive phases of intake, compression, combustion and exhaust, the method comprising: completing the intake phase of the first combustion chamber by feeding compressed air into the first combustion chamber until a maximum volume thereof is reached; during a beginning of the compression phase of the first combustion chamber and a simultaneous beginning of the intake phase of the second combustion chamber, feeding compressed air from the first combustion chamber into the second combustion chamber; closing a communication between the first and second combustion chambers and completing the intake phase of the second combustion chamber by feeding compressed air into the second combustion chamber until a maximum volume thereof is reached. 
     In further aspect, there is provided a method of feeding air to an internal combustion engine having at least first and second internal cavities, the first internal cavity defining at least a first combustion chamber with variable volume, the second internal cavity defining at least a second combustion chamber with variable volume, the method comprising: feeding compressed air to the first combustion chamber while increasing a volume of the first combustion chamber until a maximum volume thereof is reached; while reducing a volume of the first combustion chamber from the maximum volume and while increasing a volume of the second combustion chamber, feeding compressed air from the first combustion chamber into the second combustion chamber; closing a communication between the first and second combustion chambers and further reducing the volume of the first combustion chamber until a minimum volume thereof is reached; and with the communication between the first and second combustion chambers closed, feeding compressed air to the second combustion chamber while further increasing the volume thereof until a maximum volume thereof is reached. 
     In a further aspect, there is provided an internal combustion engine comprising: an outer body defining internal cavities slidingly receiving a respective one of a plurality of pistons to define a respective combustion chamber of variable volume undergoing a cycle defining successive phases of intake, compression, combustion and exhaust; at least one inlet port for each of the internal cavities and in fluid communication with the respective combustion chamber at least during the intake phase thereof and a beginning portion of the compression phase thereof; at least one exhaust port for each of the internal cavities and in fluid communication with the respective combustion chamber of the respective internal cavity during the exhaust phase thereof; a rotatable shaft, the pistons being drivingly engaged to the shaft; a plenum for receiving pressurized air; and a plurality of conduits in fluid communication with the plenum, each of the plurality of conduits defining a fluid communication between a first respective one of the internal cavities and a second respective one of the internal cavities through the at least one inlet port of the first and second respective one of the internal cavities; wherein the combustion chamber of the first respective one of the internal cavities undergoes the beginning portion of the compression phase simultaneously with the combustion chamber of the second respective one of the internal cavities undergoing a beginning portion of the intake phase. 
     In a further aspect, there is provided a system comprising: a turbocharger having a compressor; an internal combustion engine having: an outer body defining internal cavities slidingly receiving a respective one of a plurality of pistons drivingly engaged to a rotatable shaft to define combustion chambers of variable volume each undergoing a cycle defining successive phases of intake, compression, combustion and exhaust; for each of the combustion chambers, at least one inlet port in fluid communication with the combustion chamber during the intake phase and a beginning portion of the compression phase, and at least one exhaust port in fluid communication with the combustion chamber during the exhaust phase; a plenum in fluid communication with the compressor; and conduits in fluid communication with the plenum, each of the conduits defining a fluid communication between a first respective one of the combustion chambers and a second respective one of the combustion chambers through the at least one inlet port of the first and second respective one of the combustion chambers; wherein the first respective one of the combustion chambers undergoes the beginning portion of the compression phase simultaneously with the second respective one of the combustion chambers undergoing a beginning portion of the intake phase; whereby each of the conduits allows for compressed air overflowing from the at least one inlet port of the first respective one of the combustion chambers during the beginning portion of the compression phase thereof to be fed into the at least one inlet port of the second respective one of the combustion chambers. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       Reference is now made to the accompanying figures in which: 
         FIG. 1  is a schematic view of an engine in accordance with a particular embodiment; 
         FIG. 2  is a schematic cross-sectional view of a rotary internal combustion engine in accordance with a particular embodiment, which can be used in an engine such as shown in  FIG. 1 ; 
         FIG. 3  is a schematic view of connections between the cavities of a rotary engine such as shown in  FIG. 2 , in accordance with a particular embodiment; 
         FIG. 4  is a schematic cross-sectional view of a conduit of  FIG. 3 , in accordance with a particular embodiment; and 
         FIG. 5  is a schematic view of connections between the cavities of a reciprocating internal combustion engine which can be used in an engine such as shown in  FIG. 1 , in accordance with a particular embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to  FIG. 1 , an engine  8  is schematically shown. The engine  8  includes an internal combustion engine  10 ,  110  generally including a plurality of moveable bodies each received in a corresponding internal cavity of an outer body to each define at least one combustion chamber. For example, the internal combustion engine  10 ,  110  may be a reciprocating engine with a plurality of internal cavities each receiving a moveable body in the form of a reciprocating piston. The internal combustion engine  10 ,  110  may alternately be a rotary engine with a plurality of internal cavities each receiving a moveable body on the form of a rotatable body or rotor. The moveable bodies drive a common load. In the embodiment shown, the common load includes an output shaft  16  which may be for example connected to a propeller through a reduction gearbox (not shown) and to which the moveable bodies of the internal combustion engine  10 ,  110  are engaged. 
     The engine  8  also includes a turbocharger  17 , which in the embodiment shown include a compressor  19  and a turbine  22  which are drivingly interconnected by a shaft  23 . The compressor  19  and the turbine  22  may each be a single-stage device or a multiple-stage device with a single shaft or split on multiple independent shafts in parallel or in series, and may be a centrifugal or axial device. In the embodiment shown, the shaft  23  of the turbocharger  17  rotates independently of the common load. The compressor  19  of the turbocharger  17  compresses the air before it enters the internal combustion engine  10 ,  110 . 
     In a particular embodiment, the engine  8  is a compound cycle engine such as described for example in Lents et al.&#39;s U.S. Pat. No. 7,753,036 issued Jul. 13, 2010, as described in Julien et al.&#39;s U.S. Pat. No. 7,775,044 issued Aug. 17, 2010, or as described in U.S. patent application Ser. Nos. 13/554,517 and 13/554,564 both filed Jul. 20, 2012, the entire contents of all of which are incorporated by reference herein. For example, the exhaust flow is supplied to a power turbine  25  also driving the common load. The power turbine  25  is connected to the output shaft  16  through an appropriate type of transmission  27 , for example a planetary, star, offset or angular gear system. The outlet of the power turbine  25  is in fluid communication with an inlet of the turbocharger turbine  22 . Energy is extracted from the exhaust gas exiting the power turbine  25  by the turbocharger turbine  22  to drive the compressor  19  via the connecting shaft  24 . 
     In another embodiment, the internal combustion engine  10 ,  110  is not compounded and the power turbine  25  is omitted. For example, the engine  8  may include only the internal combustion engine  10  and a turbocharger  17 . The internal combustion engine  10 ,  110  operates under the principle of the Miller cycle, as will be further detailed below. 
     Referring to  FIG. 2 , in a particular embodiment, the internal combustion engine  10  is a rotary engine. Although  FIG. 2  shows a Wankel engine, it is understood that the rotary engine  10  may alternately have a different configuration than that of a Wankel engine. For example, in a particular embodiment, the rotary engine may be a single or eccentric type rotary engine in which the rotor rotates about a fixed center of rotation. For example, the rotary engine may be a sliding vane engine, such as described in U.S. Pat. No. 5,524,587 issued Jun. 11, 1996 or in U.S. Pat. No. 5,522,356 issued Jun. 4, 1996, the entire contents of both of which are incorporated by reference herein. In another particular embodiment, the rotary engine may be an oscillatory rotating engine, including two or more rotors rotating at different angular velocities, causing the distance between portions of the rotors to vary and as such the chamber volume to change. In another particular embodiment, the rotary engine may be a planetary rotating engine having a different geometry than that of the Wankel engine, such as for example a planetary engine having an internal cavity with an epitrochoid profile defining three lobes and a rotor with four apex portions. Examples of such non-Wankel rotary engines are shown in Applicant&#39;s U.S. application Ser. No. 13/750,523 filed Jan. 25, 2013, the entire contents of which is incorporated by reference herein. Other rotary engine geometries are also possible. 
     Still referring to  FIG. 2 , in the particular embodiment shown, the rotary engine  10  comprises an outer body  12  having a plurality of rotor cavities  20  (only one of which is shown) each defined by axially-spaced end walls  14  and a peripheral wall  18  extending therebetween, with a rotor  24  received in each cavity  20 . The inner surface of the peripheral wall  18  of each cavity  20  has a profile defining two lobes, which is preferably an epitrochoid. 
     The outer body  12  may be integral, containing all the rotor cavities  20 , or alternately be defined by a plurality of body portions (separate from one another or interconnected), for example each defining a respective one of the cavities  20  and receiving a respective one of the rotors  24 . 
     Each rotor  24  is received within the respective cavity  20 , with the geometrical axis of the rotor  24  being offset from and parallel to the axis of the outer body  12 . Each rotor  24  has axially spaced end faces  26  adjacent to the outer body end walls  14 , and a peripheral face  28  extending therebetween. The peripheral face  28  defines three circumferentially-spaced apex portions  30  and a generally triangular profile with outwardly arched sides. The apex portions  30  are in sealing engagement with the inner surface of peripheral wall  18  to form three rotating working or combustion chambers  32  between the inner rotor  24  and outer body  12 . A recess (not shown) is defined in the peripheral face  28  of the rotor  24  between each pair of adjacent apex portions  30 , to form part of the corresponding chamber  32 . 
     The combustion chambers  32  are sealed. Each rotor apex portion  30  has an apex seal  52  extending from one end face  26  to the other and protruding radially from the peripheral face  28 . Each apex seal  52  is biased radially outwardly against the peripheral wall  18  through a respective spring. An end seal  54  engages each end of each apex seal  52 , and is biased against the respective end wall  14  through a suitable spring. Each end face  26  of the rotor  24  has at least one arc-shaped face seal  60  running from each apex portion  30  to each adjacent apex portion  30 , adjacent to but inwardly of the rotor periphery throughout its length. A spring urges each face seal  60  axially outwardly so that the face seal  60  projects axially away from the adjacent rotor end face  26  into sealing engagement with the adjacent end wall  14  of the cavity. Each face seal  60  is in sealing engagement with the end seal  54  adjacent each end thereof. 
     Although not shown, each rotor  24  is journaled on an eccentric portion of a shaft and includes a phasing gear co-axial with the rotor axis, which is meshed with a fixed stator phasing gear secured to the outer body co-axially with the shaft. The shaft rotates each rotor  24  and the meshed gears guide the rotor  24  to perform orbital revolutions within the respective internal cavity  20 . The shaft rotates three times for each complete rotation of one rotor  24  as it moves around the respective internal cavity  20 . Oil seals are provided around the phasing gear to prevent leakage flow of lubricating oil radially outwardly thereof between the respective rotor end face  26  and outer body end wall  14 . 
     During each rotation of the rotor  24 , each chamber  32  varies in volumes and moves around the internal cavity  20  to undergo cycles with each cycle including the four phases of intake, compression, expansion and exhaust, these phases being similar to the strokes in a reciprocating-type internal combustion engine having a four-stroke cycle. 
     For each cavity  20 , a primary inlet port  40  is defined through one of the walls of the stator body  12  for admitting air in turn into each of the combustion chambers  32 . In the embodiment shown, the primary inlet port  40  is a peripheral port defined as an opening through the peripheral wall  18 . In another embodiment, the primary inlet port  40  may have a different configuration, for example be defined through one of the end walls  14 , with another primary inlet port being optionally defined in the other one of the end walls  14 . The primary inlet port  40  is in fluid communication with the turbocharger compressor  19  (see  FIG. 1 ), as will be further detailed below. The primary inlet port  40  is in fluid communication with each combustion chamber  32  during the intake phase thereof and a beginning of the compression phase thereof. As such, the rotary engine  10  operates under the principle of the Miller cycle, with its volumetric compression ratio lower than its volumetric expansion ratio, and with the primary inlet port  40  remaining open, i.e. in communication with the chamber  32 , during the beginning of the compression phase. 
     For each cavity  20 , an exhaust port  44  is defined through one of the walls of the stator body  12  for discharge of the exhaust gases from the combustion chambers  32 . In the embodiment shown, the exhaust port  44  is a peripheral port defined as an opening through the peripheral wall  18 . In another embodiment, the exhaust port  44  may have a different configuration, for example be defined through one of the end walls  14 , with another exhaust port being optionally defined in the other one of the end walls  14 . 
     For each cavity  20 , a secondary inlet port or purge port  42  is also defined through one of the walls of the stator body  12  for admitting air in turn into each of the combustion chambers  32 . The secondary inlet port  42  is located rearwardly of the primary inlet port  40  and forwardly of the exhaust port  44  relative to the direction R of the rotor revolution and rotation. In the embodiment shown, the secondary inlet port  42  is a peripheral port defined as an opening through the peripheral wall  18 . In another embodiment, the secondary inlet port  42  may have a different configuration, for example be defined through one of the end walls  14 , with another secondary inlet port being optionally defined in the other one of the end walls  14 . The secondary inlet port  42  is also in fluid communication with the turbocharger compressor  19  (see  FIG. 1 ), as will be further detailed below. The secondary inlet port  42  is in fluid communication with each combustion chamber  32  during a portion of its cycle; this portion may include a beginning of the intake phase and/or an end of the exhaust phase. 
     In the present specification including the claims, “intake phase” is intended to refer to the portion of the cycle during which the chamber  32  is in communication with at least one inlet port  40 ,  42  and during which the volume of the chamber  32  increases such as to draw air therein, while “compression phase” is intended to refer to the portion of the cycle between the intake phase and the ignition phase during which the volume of the chamber  32  decreases, starting at the point in the cycle where the maximum chamber volume is reached after intake, regardless if actual air compression occurs. For example, in a particular embodiment, compression may be inexistent or minimal during the beginning of the compression phase when the primary inlet port  40  is open. 
     In use, through each rotation of the rotor  24 , each chamber  32  is filled with compressed air through the primary inlet port  40  and the secondary inlet port  42  during its intake phase as its volume increases. The air is then further compressed as by reducing the volume of the rotating chamber  32 , with the beginning of the compression phase being performed with the primary inlet port  40  still open, i.e. in communication with the chamber  32 , the primary inlet port  40  closing during the compression phase. Once the air is further compressed, near minimum volume of the chamber  32 , the ignition phase occurs: the air is mixed with fuel from a fuel source  9  (see  FIG. 1 ) and the resulting air-fuel mixture is ignited. In a particular embodiment, the fuel is heavy fuel e.g. diesel, kerosene (jet fuel), equivalent biofuel, etc. Alternately, the fuel may be any other adequate type of fuel suitable for injection as described, including non-heavy fuel such as for example gasoline or liquid hydrogen fuel. The fuel is delivered such that the chamber  32  is stratified with a rich fuel-air mixture near the ignition source and a leaner mixture elsewhere, thus providing a so-called stratified charge arrangement, and the fuel-air mixture may be ignited within the housing using any suitable ignition system known in the art. The rotary engine  10  may include a pilot subchamber (not shown) receiving the ignition system and a pilot injector injecting a portion of the fuel therein for ignition. 
     After ignition, the combustion gases expand and force the volume of the chamber  32  to increase. The combustion or exhaust gases exit the chamber  32  through the exhaust port  44  during the exhaust phase. At the end of the exhaust phase, the chamber  32  may communicate with both the secondary inlet port  42  and the exhaust port  44 , and the air entering the chamber  32  through the secondary inlet port  42  may be used to purge remaining exhaust gases from the chamber  32 . 
     Referring to  FIG. 3 , a connection arrangement between the different cavities of the rotary engine  10  is shown. In the embodiment shown, the rotary engine  10  includes two rotor cavities  20   a,b , each receiving a respective rotor  24  (not shown in  FIG. 3 ) and each having a primary inlet port  40   a,b  and a secondary inlet port  42   a,b  in communication with the combustion chambers defined therein. 
     A first conduit  62  provides for fluid communication between the primary inlet port  40   a  of the first cavity  20   a  and the secondary inlet port  42   b  of the second cavity  20   b . A second conduit  64  provides for fluid communication between the primary inlet port  40   b  of the second cavity  20   b  and the secondary inlet port  42   a  of the first cavity  20   a . A plenum  21  receives the compressed air from the turbocharger compressor  19 , and the first and second conduits  62 ,  64  are also in fluid communication with the plenum  21 . 
     The rotors are engaged to the shaft in an angularly offset manner. Each combustion chamber defined in the first cavity  20   a  undergoes the beginning of its compression phase (i.e. the part of the compression phase where the primary inlet port  40   a  communicates with the chamber) while a corresponding combustion chamber defined in the second cavity  20   b  undergoes at least part of the portion of its cycle in communication with its secondary inlet port  42   b , which in a particular embodiment is at the beginning of its intake phase. As such, the first conduit  62  allows for the compressed air overflowing from the primary inlet port  40   a  of the first cavity  20   a  during the beginning of its compression phase to be fed into the secondary inlet port  42   b  of the second cavity  20   b , in a particular embodiment together with air from the plenum  21 . 
     Similarly, each combustion chamber defined in the second cavity  20   b  undergoes the beginning of its compression phase (i.e. the part of the compression phase where the primary inlet port  40   b  communicates with the chamber) while a corresponding combustion chamber defined in the first cavity  20   a  undergoes at least part of the portion of its cycle in communication with its secondary inlet port  42   a , which in a particular embodiment is at the beginning of its intake phase. As such, the second conduit  64  allows for the compressed air overflowing from the primary inlet port  40   b  of the second cavity  20   b  during the beginning of its compression phase to be fed into the secondary inlet port  42   a  of the first cavity  20   a , in a particular embodiment together with air from the plenum  21 . 
     In a rotary engine including more than two rotors, the rotor cavities may be connected in pairs, i.e. with the first and second conduits interconnecting the same rotor cavities, or connected with different rotor cavities, i.e. with the primary inlet port of a first rotor being connected to the secondary inlet port of a second rotor and the secondary inlet port of the first rotor being connected to the primary inlet port of a third rotor, based on the relative timing (angular offset) of the rotors. 
     Referring to  FIG. 4 , a particular embodiment for the first conduit  62  is shown, with the second conduit  64  being identical or similar thereto. The conduit  62  is configured such as to form a Venturi to assist in the circulation of compressed air from the primary inlet port  40   a  of the first cavity  20   a  to the secondary inlet port  42   b  of the second cavity  20   b . In a particular embodiment, the conduit  62  has a circular cross-section. The conduit includes a first segment  86  extending from the plenum  21 . A second segment  88  extends from the first segment  86 , and receives the connection with the primary inlet port  40   a  of the first cavity  20   a . A third segment  90  extends from the second segment  88  and a fourth segment  92  extends from the third segment  90 , with the third segment providing for a gradual transition between the different dimensions of the second and fourth segments  88 ,  92 . The fourth segment  92  receives the fluid communication with the secondary inlet port  42   b  of the second cavity  20   b.    
     It can be seen that the second segment  88  has a diameter D 2  which is smaller than the diameter D 1  of the first segment  86 , and smaller than the diameter D 3  of the fourth segment  92 . In a particular embodiment, the ratio D 1 /D 2  and the ratio D 1 /D 3  are between 1 and 2. In another particular embodiment, the ratio D 1 /D 2  and the ratio D 1 /D 3  are from about 1.5 to about 1.8. Other values are also possible. 
     The third segment  90  is tapered to define a progressive transition between the different diameters D 2  and D 3  of the second and fourth segments  88 ,  92 . The outer wall of the third segment  90  extends at an angle α from the outer wall of the fourth segment  92 . In a particular embodiment, the angle α is from about 2.5° to about 7.5°. In another particular embodiment, the angle α is from about 3° to about 4°. Other values are also possible. 
     In the embodiment shown, the fluid communication between the primary inlet port  40   a  and the second segment  88  is provided through a conduit portion  94  extending at an angle θ with respect to a perpendicular to a central axis C of the second segment  88 . In a particular embodiment, the angle θ is from about −45° to about 60°. In another particular embodiment, the angle θ is from about 30° to about 60°. Other values are also possible. 
     In use, the compressed air is fed into the combustion chambers  32  of the rotary engine  10  in accordance with the following. The compressed air from the plenum  21  is fed through the first conduit  62  and into a combustion chamber of the first cavity  20   a  through its primary inlet port  40   a  as the chamber undergoes the intake phase, i.e. as its volume is increasing. Compressed air is also fed to the chamber through the second conduit  64  through its secondary inlet port  40   a  during the beginning of the intake phase, and optionally the end of the exhaust phase. 
     After the intake phase, when the maximum volume of the chamber is reached, the compression phase begins and the volume of the chamber of the first cavity  20   a  is reduced, at first while its primary inlet port  40   a  remains open. The air overflows out of the first cavity  20   a  through the open primary inlet port  40   a  and into the first conduit  62 , where it is fed to a combustion chamber of the second cavity  20   b  through its secondary inlet port  42   b , with the chamber of the second cavity  20   b  being at the end of its exhaust phase or at the beginning of its intake phase. The chamber of the second cavity  20   b  undergoes the beginning of its intake phase, with its volume increasing, while the air from the first cavity  20   a  is received through its secondary inlet port  42   b . Depending on the relative pressures, air may also be fed from the plenum  21  to the second cavity  20   b  through the first conduit  62  and secondary inlet port  42   b . The communication between the combustion chamber of the first cavity  20   a  and its primary inlet port  40   a  is then closed, and the air within the combustion chamber of the first cavity  20   a  is further compressed during the remainder of the compression phase as the volume of the chamber is reduced to its minimum value. 
     The intake phase of the chamber of the second cavity  20   b  continues, and compressed air is fed from the plenum  21  through the second conduit  64  and into the combustion chamber of the second cavity  20   b  through its primary inlet port  40   b . After the intake phase, when the maximum volume of the chamber is reached, the compression phase begins and the volume of the chamber of the second cavity  20   b  reduces, at first while its primary inlet port  40   b  remains open. The air overflows out of the second cavity  20   b  through the open primary inlet port  40   b  and into the second conduit  64 , where it is fed to another combustion chamber of the first cavity  20   a  through its secondary inlet port  42   a , this chamber of the first cavity  20   a  being at the end of its exhaust phase or at the beginning of its intake phase. This other chamber of the first cavity  20   a  undergoes the beginning of its intake phase, with its volume increasing, while the air from the second cavity  20   b  is received through its secondary inlet port  42   a . Depending on the relative pressures, air may also be fed from the plenum  21  to the first cavity  20   a  through the second conduit  64  and secondary inlet port  42   a . The communication between the chamber of the second cavity  20   b  and its primary inlet port  40   b  is then closed, and the air within the combustion chamber of the second cavity  20   b  is further compressed until the end of its compression phase as the volume of the chamber is reduced to its minimum value. 
     Referring to  FIG. 5 , a similar connection arrangement between the different cavities of a reciprocating engine  110  is shown. In the embodiment shown, the reciprocating engine  110  includes four cavities  120   a,b,c,d  each receiving a respective piston  124   a,b,c,d  to each define a single combustion chamber, and each having a respective inlet port  140   a,b,c,d ′ and a respective exhaust port  144   a,b,c,d  in communication with the combustion chamber. A respective valve selectively allows and prevents the fluid communication between the inlet ports  140   a,b,c,d  and the respective cavity  120   a,b,c,d  and between the exhaust ports  144   a,b,c,d  and the respective cavity  120   a,b,c,d.    
     A plenum  121  receives the compressed air from the turbocharger compressor  19 . First, second, third and fourth conduits  162 ,  164 ,  166 ,  168  are defined by different sections of interconnected passages which selectively communicate with each other through one-way valves. 
     The pistons  124   a,b,c,d  are engaged to the shaft in an angularly offset manner with each cavity  120   a,b,c,d  undergoing the beginning of its compression phase with its inlet port open while another cavity undergoes part or all of its intake phase with its inlet port also open. In the embodiment shown, the pistons fire in the following order: first piston  124   a , second piston  124   b , fourth piston  124   d  and third piston  124   c.    
     As such, in the embodiment shown, first, second, third and fourth inlet passages  170   a,b,c,d  extend from a respective one of the inlet ports  140   a,b,c,d  to the plenum  121 . A first transverse passage  172  interconnects the first, second and fourth inlet passages  170   a,b,d , while a second transverse passage  174  interconnects the first, third and fourth inlet passages  170   a,c,d . A first one-way valve  176   a  allows a flow in the first transverse passage  172  from the first inlet passage  170   a  to the second inlet passage  170   b  while preventing the flow in the opposite direction. A second one-way valve  176   b  allows a flow in the first transverse passage  172  from the second inlet passage  170   b  to the fourth inlet passage  170   d  while preventing the flow in the opposite direction. A third one-way valve  176   c  allows a flow in the second transverse passage  174  from the fourth inlet passage  170   d  to the third inlet passage  170   c  while preventing the flow in the opposite direction. A fourth one-way valve  176   d  allows a flow in the second transverse passage  174  from the third inlet passage  170   c  to the first inlet passage  170   a  while preventing the flow in the opposite direction. 
     Thus, in the embodiment shown, when the first cavity  120   a  is at the beginning of its compression phase with the valve of its inlet port  140   a  remaining open, the second cavity  120   b  is in its intake phase, with the valve of its inlet port  140   b  also being open. A first conduit  162  provides for fluid communication between the first inlet port  140   a  and the second inlet port  140   b , as defined by the first inlet passage  170   a , the portion of the first transverse passage  172  extending between the first and second inlet passages  170   a,b  including the first one-way valve  176   a , and the second inlet passage  170   b . The valves of the third and fourth inlet ports  140   c,d  are closed and prevent communication of the first conduit  162  with the third and fourth cavities  120   c,d.    
     The second cavity  120   b  then begins its compression phase with the valve of the second inlet port  140   b  remaining open, and the fourth cavity  120   d  is in its intake phase, with the valve of the fourth inlet port  140   d  also being open. A second conduit  164  provides for fluid communication between the second inlet port  140   b  and the fourth inlet port  140   d , defined by the second inlet passage  170   b , the portion of the first transverse passage  172  extending between the second and fourth inlet passages  170   b,d  including the second one-way valve  176   b , and the fourth inlet passage  176   d . The valves of the first and third inlet ports  140   a,c  are closed and prevent communication of the second conduit  164  with the first and third cavities  120   a,c.    
     The fourth cavity  120   d  then begins its compression phase with the valve of the fourth inlet port  140   d  remaining open, and the third cavity  120   c  is in the intake phase, with the valve of the third inlet port  140   c  also being open. A third conduit  166  provides for fluid communication between the fourth inlet port  140   d  and the third inlet port  140   c , defined by the fourth inlet passage  170   d , the portion of the second transverse passage  174  extending between the fourth and third inlet passages  170   d,c  including the third one-way valve  176   c , and the third inlet passage  170   c . The valves of the first and second inlet ports  140   a,b  are closed and prevent communication of the third conduit  166  with the first and second cavities  120   a,b.    
     The third cavity  120   c  then begins its compression phase with the valve of the third inlet port  140   c  remaining open, and the first cavity  120   a  is in the intake phase, with the valve of the first inlet port  140   a  also being open. A fourth conduit  168  provides for fluid communication between the third inlet port  140   c  and the first inlet port  140   a , defined by the third inlet passage  170   c , the portion of the second transverse passage  174  extending between the third and first inlet passages  170   c,a  including the fourth one-way valve  176   d , and the first inlet passage  170   a . The valves of the second and fourth inlet ports  140   b,d  are closed and prevent communication of the fourth conduit  168  with the second and fourth cavities  120   b,d.    
     The conduits  162 ,  164 ,  166 ,  168  are also in communication with the plenum  121  through the inlet passages  170   a,b,c,d . In a particular embodiment, the conduits  162 ,  164 ,  166 ,  168  have a Venturi shape as described above. 
     In an alternate embodiment, the internal combustion engine  10 ,  110  is a rotary engine with a single inlet port for each cavity, and a communication similar to that described above for the reciprocating engine  110  is provided. An another embodiment, the internal combustion engine  10 ,  110  is a reciprocating engine with a primary and a secondary inlet port for each cavity, and a communication similar to that described above for the rotary engine  10  is provided. 
     In a particular embodiment, the conduits  62 ,  64 ,  162 ,  164 ,  166 ,  168  which allow circulation of the air expelled from each cavity  20   a,b ,  120   a,b,c,d  at the beginning of the compression phase of each chamber into a chamber of another cavity  20   a,b ,  120   a,b,c,d  simultaneously undergoing its intake phase allow for a reduction of the pressure losses which may otherwise be associated with the use of the Miller cycle in an internal combustion engine. 
     In a particular embodiment, the internal combustion engine  10 ,  110  is a premix engine where the fuel is for example gasoline, and the fuel may be injected in the inlet port; in this case, the air circulated between the inlet ports may also include fuel mixed therewith. 
     The above description is meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the invention(s) disclosed. Modifications which fall within the scope of the present invention will be apparent to those skilled in the art, in light of a review of this disclosure, and such modifications are intended to fall within the appended claims.