Patent Publication Number: US-3874346-A

Title: Internal combustion engine

Description:
United States Patent [191 Frietas Apr. 1, 1975 1 1 INTERNAL COMBUSTION ENGINE [75] Inventor: Daniel A. Frietas, San Jose, Calif.  
 [73] Assignee: The Foreitas Engine Company, San  
 Jose, Calif.  
 [22] Filed: Feb. 5, 1973 21 Appl. No.: 329,604  
 Primary E.raminerWendell E. Burns [57] ABSTRACT The disclosed embodiment of the present invention is an internal combustion engine having a combustion section and a scavenging and charging pump section. The combustion section has at least one movable member which is comparable functionally to a piston and which is mounted for rotation about an axis which is parallel to and spaced from the axis of a crankshaft. The movable member is connected to the crankshaft by means of a connecting rod. The pivotal connecting point of the movable member with the connecting rod follows an arcuate path such that movement from the top dead center position to the bottom dead center position encompasses a rotational displacement of more than 180 of the crankshaft. An intake port, exhaust port, and transfer port are located on a wall of the engine block and are open and closed by movement of the movable member. .A transfer recess is provided in the movable member and provides fluid communication between the intake and transfer ports during a portion of the cycle of operation. The scavenging and charging pump section has a movable member which is similar structurally to and is mounted similarly to the movable member of the combustion section. However, the pump section is arranged to achieve a top dead center&#34; position from 80 to 130 before the combustion section achieves a top dead center&#34; position. The transfer port provides fluid communication between the combustion section and pump section.  
 12 Claims, 6 Drawing Figures INTERNAL COMBUSTION ENGINE FIELD OF THE INVENTION This invention relates generally to an energy conversion device and more particularly to a two-cycle internal combustion engine for use in a motive power system.  
 BACKGROUND OF THE INVENTION The well-known piston engine in which a cylindrical piston is mounted for reciprocal movement in a cylindrical chamber has a number of distinctive disadvantages. In such an engine, a cylindrical piston is mounted within a cylinder and is attached to a crankshaft by a connecting rod. A fuel-air mixture is supplied to the cylinder and compressed by the movement of the piston in a direction to reduce the volume occupied by such a mixture. When the compressed fuel-air mixture is ignited, the temperature of the resulting gas increases, thereby causing the gas to attempt to expand. When the pressure within the cylinder increases, a force is exerted on the face of the piston which attempts to move it axially within the cylinder. Such movement of the piston causes the crankshaft to rotate by virtue of its connection via the connecting rod thereto. As is well known, appropriate valving permits the intake of the fuel-air mixture and the exhaust of the expended gases from the ignition of such a mixture. Such a thermodynamic cycle converts energy in the form of heat into mechanical rotary movement.  
  The above described structure can be employed as either a two-cycle or a four-cycle engine in accordance with the valving arrangement employed for the intake of the fuel-air mixture and the exhaust of the expended gases from the ignition of such a mixture. Regardless of the valving arrangement, the above described structure does not convert energy in the form of heat into mechanical movement in the most efficient manner. Furthermore, such structure suffers from several distinct disadvantages.  
  The maximum ideal power stroke of such an engine corresponds to a rotational displacement of the crankshaft of 180. However, because of a number of factors, such an ideal maximum power stroke cannot be achieved for maximum efficiency. One ofthe most serious problems encountered in attempting to accomplish maximum efficiency is that of optimizing the inlet and exhaust system in an attempt to reduce undesirable oscillatory conditions in the flow of the fuel-air mixture into the cylinder and the discharge of exhaust gases therefrom. For example, in the engines of many of the recent model automobiles in which high performance is required, the exhaust port is open at approximately 90 from top dead center (TDC) in the power stroke in order to reduce fluid oscillations and thereby improve efficiency. The length of the power stroke is directly related to the position of the piston when the exhaust port is open. Accordingly, any reduction in the position from top dead center at which the exhaust port is permitted to open results in a reduction of the length of the power stroke. Obviously a compromise must be achieved. which reduces the efficiency of such an engine considerably from its optimum ideal efficiency.  
  A similar problem is encountered in many of the known two-cycle engines, in which the piston wall forms part of the exhaust (and intake) valving structure and the exhaust port is open by movement of the piston to and beyond a particular position. If top dead center is located 180 from bottom dead center, the opening of the exhaust port must occur at some position considerably less than 180 from top dead center.&#34; Generally, the position of the crankshaft from the top dead center position at which the exhaust port begins to open is in the range of from to Accordingly, the length of the power stroke in the known two-cycle engines is not any greater than that in a high performance four-cycle engine.  
  Furthermore, many two-cycle engine designs employ the crank case volume as a scavenging and charging pump. Such a design employs the movement of the piston in an upward direction (compression stroke) to effect a pumping action. However, since the entire crank case volume cannot be swept [by the piston, the scav enging and charging action is not as effective as may be desired. Although the scavenging and charging action in such a design can be increased by reducing the crank case volume to a minimum, the maximum ideal action cannot be achieved. Furthermore, a reduction of the crank case volume results in other undesirable design considerations.  
  The well known piston engine is also susceptible to considerable deterioration in the form of cylinder wall wear due to the action of the piston thereon. When the piston is at top dead center, the connecting rod is axially aligned therewith. However, as the piston moves from top dead center the connecting rod becomes angularly displaced from such an axial position. Accordingly, the forces exerted through the connecting rod to the piston at positions other than top dead center and bottom dead center have a component which is orthogonal to the axis of the piston, thereby resulting in excessive wear on two diammetrically opposed surfaces of the cylinder wall.  
 SUMMARY OF THE INVENTION Accordingly, it is a primary object of the present invention to provide an internal combustion engine having a relatively high efficiency.  
  A related object of the present invention is to provide an internal combustion engine having a relatively high power-to-weight ratio.  
  Another object of the present invention is to provide an internal combustion engine in which the forces produced by combustion are imparted to the crankshaft more efficiently.  
  Another object of the present invention is to provide an internal combustion engine which is not susceptible to the problem encountered in the well known piston engine of wear on the cylinder walls.  
  Yet another object of the present invention is to provide an internal combustion engine having relatively few moving parts, thereby improving its reliability.  
  These and other objects are attained by a structural arrangement in which the displacement of a movable member, comparable functionally to a piston, from the top dead center position to the bottom dead center position encompasses more than a angular displacement of the crankshaft. More particularly, such a movable member is mounted for rotational movement about an axis which is parallel to and spaced from an axis of the crankshaft. In addition, a radius from the axis of rotation of the movable member to the connection point between the movable member and a connecting rod is greater than the distance from the axis of rotation of the movable member to the axis of the crankshaft, whereby the connection point tends to follow the crankshaft around in its rotational displacement.  
  A feature of the present invention resides in the provision of a combustion section and a scavenging and charging pump section which are mounted on a common crankshaft in tandem with one another.  
  A further feature of the present invention resides in the provision of a movable member in the combustion section and a movable member in the pump section which are structurally similar to one another and are each mounted as described above to follow the angular displacement of the crankshaft.  
  Another feature of the present invention resides in the provision of an intake port, an exhaust port, and a transfer port in the combustion section, each of which are positioned to be opened and closed by the movable member, and the provision of a transfer recess in the movable member in the combustion section for providing fluid communication between the inlet port and the pump section via the transfer port.  
  The invention, however, as well as other objects, features and advantages thereof will be more fully realized and understood from the following detailed description, when taken in conjunction with the accompanying drawings, wherein:  
 DESCRIPTION OF THE FIGURES FIG. 1 is a sectional view along a diammetric axis of the crankshaft of the engine of the present invention;  
  FIG. 2 is a sectional view taken generally along line 2-2 of FIG. 1;  
  FIG. 3 is a sectional view taken generally along line 3-3 of FIG. 1;  
  FIG. 4 is a sectional view taken generally along line 44 of FIG. 2;  
  FIG. 5 is a plan view of one face of one of the pistons illustrated in FIG. 2 illustrating the transfer recess therein; and  
  FIG. 6 is a graphical representation of the operating cycle of the engine of the present invention.  
  Like reference numerals throughout the various views of the drawings are intended to designate the same elements.  
 DESCRIPTION OF THE PREFERRED EMBODIMENT The exemplification which is described herein employs the principles of the present invention in a twocycle configuration, but it is to be understood that the principles of the present invention are equally applicable to a four-cycle engine, a steam engine, or any other energy converting device which employs expanding gasses for moving a member to cause rotation of the crankshaft.  
  With particular reference to FIG. 1, there is shown a two-cycle engine constructed in accordance with the principles of the present invention which includes a combustion section indicated generally with the reference numeral 10 and a scavenging and charging pump section indicated generally with the reference numeral 12. The combustion section 10 is enclosed by a housing which is formed by a peripheral wall 14 and a pair of end walls 16 and 18. In essence, the walls 14, 16, and  
 18 form the block of the engine with certain internal surfaces thereof forming the surfaces of the working volume of the engine and correspond to the cylinder in the well-known piston engine. The scavenging and charging pump section 12 is enclosed by a housing which is formed by a peripheral wall 20, the end wall 18, and an end wall 22. It can be readily appreciated from the drawings that the wall 18 is common to both of the sections 10 and 12 and that the sections 10 and 12 are axially aligned in tandem with one another.  
  Mounted within the combustion section 10 are a pair of movable members 24 and 26, each of which are functionally comparable to a piston and will, therefore, be referred to as pistons hereinbelow. The pistons 24 and 26 are formed by substantially rectangular shaped members 28 and 30, respectively, each having a slight curvature. Extending from one end of the member 28 is a flange 32 having a transfer recess 34 therein. The face of the flange 32 and the transfer recess 34 therein are illustrated more clearly in FIG. 5. The member 30, which is identical to the member 28, is also provided with a flange 36 having a transfer recess 38 therein. One end of the piston 24 is mounted for rotation on a pin 40 and one end of the piston 26 is mounted for rotation on a pin 42. A pair of flanges, one of which is des-.  
 ignated with the reference numeral 44, extend from an edge of the member 28 to the flange 32 and are disposed for receiving a wrist pin 46 in appropriate apertures therein. Similar flanges are provided on the piston 26 which are adapted to receive a wrist pin 48 in appropriate apertures therein.  
  A connecting rod 50 is pivotally mounted at one end thereof on the wrist pin 46 and a connecting rod 52 is pivotally mounted at one end thereof on the wrist pin 48. A crankshaft 54 is mounted in the walls 16, 18, and 22 and is provided with a crankpin 56 for pivotally supporting the other ends of the connecting rods 50 and 52.  
  The pins 40 and 42 are mounted between the walls 16 and 18 and on diammetrically opposite sides from the crankshaft 54 with an axis of each being parallel to and spaced from an axis of the crankshaft 54. With particular reference to FIG. 2, the piston 24 is shown therein at its top dead center position. If the crankshaft 54 is rotating in a direction as indicated by an arrow 58, the piston 26 is shown in FIG. 2 as being in a position which is arrived at prior to its bottom dead center position. In the illustrated embodiment of the present invention, the bottom dead center position of each of the pistons 24 and 26 is spaced 30 from the top dead center position of the opposite piston. Because of the arcuate path of the wrist pins 46 and 48, the connecting rods 50 and 52 tend to follow the crankpin 56 around in its rotational movement. In a constructed embodiment of the present invention, the piston stroke from top dead center to bottom dead center corresponded to a rotational displacement of 210 of the crankshaft 54. The piston stroke from bottom dead center to top dead center, therefore, encompasses a rotational displacement of the crankshaft 54 of The scavenging and charging pump section 12 is provided with a pair of pistons 60 and 62 which, with the exception of the absence of flanges comparable to the flanges 32 and 36, are similar to the pistons 24 and 26. The crankshaft 54 is provided with a crankpin 64 to which a pair of connecting rods 66 and 68 are pivotally connected. The connecting rod 66 is pivotally secured to the piston 60 by means of a wrist pin 70 and the connecting rod 68 is pivotally secured to the piston 62 by means of a wrist pin 72. In addition, the pistons 60 and 62 are mounted for rotational movement on pins 74 and 76, respectively and are axially aligned with pins 40 and 42, respectively.  
  With particular reference to FIGS. 2 and 4, an intake port 78 extends through the peripheral wall 14 and serves to supply air from the external surroundings into the transfer recess 34 of the piston 24. A similar intake port 80 is provided for supplying air to the recess 38 of the piston 26. A transfer port 81 is connected to a passage 82 which extends from the combustion section to a port 83 in the scavenging and charging pump section 12. During a portion of the cycle of operation, the passage 82 provides fluid communication between the recess 34 and the pump section 12. During another part of the cycle of operation, the passage 82 provides fluid communication between the piston-swept working volume of the combustion section 10 and the pump section 12. A similar transfer port 84, passage 85, and port 86 are provided for that portion of the combustion section associated with the piston 26. A pair of exhaust ports 87 and 88 extend through the peripheral wall 14 and are disposed for providing fluid communication between a respective piston-swept working volume and the external surroundings. As shown in FIG. 5, the recess 34 is provided in only a portion of the face of the flange 32 so that it does not communicate with the exhaust port 36.  
  It will be noted from FIGS. 2 and 3 that the crankpin 64 leads the crankpin 56 in the rotational displacement of the crankshaft 54. In a constructed embodiment of the present invention, the crankpin 64 is out of phase by l l0 from the crankpin 56. During operation of the engine, when the piston 60 has passed top dead center, it begins to draw air from the external surroundings via the intake port 78, the recess 34, transfer port 81, passage 82, and port 83. When the piston 60 has passed its bottom dead center position, the piston 24 has moved to a position in which the transfer port 81 is in fluid communication with the piston-swept working volume associated therewith. During upward movement of the piston 60 from its bottom dead center position, air is forced through the passage 82 and the transfer port 81 into the working volume to scavenge the exhaust gases therefrom which escape from the exhaust port 87. When the exhaust port 87 is closed by the face of the flange 32, continued displacement of the piston 24 in an upward direction compresses the gases therein. In the illustrated embodiment of the present invention, fuel is supplied to the working volumes and combustion chambers by means offuel injectors 90 and 92. The resulting air-fuel mixtures entraped in the combustion chambers are ignited by spark plugs 94 and 96.  
  A better understanding of the operation of the disclosed device will be realized from the graphical representation in FIG. 6 of one cycle of the engines operation. FIG. 6 is a graphical representation of the angular displacement of the crankpin 56 around the axis of the crankshaft 54 and the various functions which occur at predetermined positions thereof. A vertical line designated with the reference numeral 98 represents the angular position of the crankpin 56 when the piston 24 is located at its top dead center position.  
  A radial line represents the angular position of the crankpin 56 when the piston 60 is located at its bottom dead center position. A radial line 102 represents the angular position of the crankpin 56 when the transfer port 81 is closed from fluid communication with the intake port 78 by the face of the piston 24. A radial line 104 represents the angular position of the crankpin 56 when the transfer port 81 is first open for fluid communication with the exhaust port 87. Accordingly, a displacement of the crankpin 56 from the position represented by the radial line 98 to the position represented by the radial line 104 corresponds to the power stroke of the engine. Such a power stroke is represented by the arcuate line designated with the reference numeral 106. In a constructed embodiment of the present invention, if the radial line 98 is considered as 0, the radial line 100 is located at 100, the radial line 102 is located at l38.5, and the radial line 104 is located at 145. In such a constructed embodiment of the present invention, therefore, the power stroke encompasses a rotational displacement of the crankshaft 54 of 145.  
  A radial line 108 corresponds to the angular position of the crankpin 56 when the piston 24 is at its bottom dead center position. A radial line 110 correspondsto the angular position of the crankpin 56 when the piston 60 is located at its top dead center position. In the above mentioned constructed embodiment of the present invention, the line 108 is located at 210 and the line 110 is located at 250 from the line 98.  
  A radial line 112 corresponds to the angular position of the crankpin 56 when the transfer port 81 is closed from fluid communication with the exhaust port 87 by the face of the piston 24. Accordingly, the exhaust portion of the cycle of operation corresponds to an angular displacement of the crankpin 56 from the line 104 to the line 112 as represented by the arcuate line designated with the reference numeral 114. Furthermore, angular displacement of the crankpin 56 from the line 112 to the line 98 as represented by the arcuate line designated with the reference numeral 116, corresponds to the compression stroke. A radial line 118 represents the angular position of the crankpin 56 when the intake port 78 is open to fluid communication with the transfer port 81. Accordingly, angular displacement of the crankpin 56 from a position corresponding to the line 118 to a position corresponding to the line 102 as represented by an arcuate line 120 corresponds to the intake portion of the cycle of operation. In the above mentioned constructed embodiment of the present invention, the line 112 is located at 260 and the line 118 is located at 265.5 from the line 98.  
  For greater clarity of illustration, certain necessary features and structures have not been shown or described in the exemplified form of the present invention. For example, the necessary bearings and seals, particularly for the crankshaft 54; the necessary passages, lines, and pump for lubercating oil; the necessary cooling structures; and the fasteners for securing various parts to one another have not been shown. However, such elements are well known in the art and are not necessary for purposes of understanding the present invention.  
  In the above described embodiment of the present invention, the working volume of the engine is charged with fuel by fuel injectors 92 and 94. It is to be understood, however, that the working volume of the engine can be charged with an air-fuel mixture by means of a carburator attached to the intake passages. Furthermore, the particular valving and transfer arrangement illustrated in the drawings and described hereinabove can be performed by other well known valving and transfer arrangements. Furthermore, it can be readily appreciated that more than two pistons can be mounted in one section, such as the combustion section 10, and that a plurality of sections can be connected in tandem with one another on a common crankshaft.  
  The above described embodiment of the present invention provides a number of advantages not realized by prior known engines. For example, the engine of the present invention provides more power output per cubic inch displacement, particularly because of the longer expansion or power stroke which is achieved. Furthermore, because of the&#39;pivotal rotation of the pistons 24 and 26 on the pins 40 and 42, respectively, and the anchoring action which is performed by such pins, the typical wear associated with the well known piston engine on the cylinder walls is eliminated. A particular feature of the present invention which provides a distinct advantage is the use of the flanges 32 and 36 which provide cooling for the pistons 24 and 26, respectively. It can be readily appreciated that the engine of the present invention has relatively few moving parts, thereby providing a distinct advantage over some of the other prior known structures. Furthermore, many of the parts employed in the engine of the present invention are identical, thereby reducing manufacturing costs.  
  As previously mentioned, the teachings of the present invention can be employed in the construction of a four-cycle engine, a steam engine, or any other energy converting device which employs expanding gases for moving a member to cause rotation of a crankshaft. The major difference between such energy conversion devices is that of the valving structures employed.  
 The invention claimed is:  
 1. An energy conversion device comprising a. a housing,  
 b. a crankshaft extending through said housing,  
 c. a first piston member mounted for reciprocal and pivotal movement in said housing on an axis which is parallel to the axis of rotation of said crankshaft, and  
 d. a connecting rod pivotally mounted at one end thereof to said first piston member and at the other end thereof to said crankshaft, the shape of said piston member and portions of the internal surfaces of said housing forming a working volume which is approximately triangular in a cross sectional plane transverse to the axis of rotation of said crankshaft throughout the stroke of said piston member, the relative dimensions from the axis of said crankshaft to the axis of rotation of said piston, from the axis of rotation of said piston to the connection of said connecting rod with said piston, of the length of said connecting rod, and of the stroke of said piston providing from a top dead center position to a bottom dead center position of said piston a rotational displacement of said crankshaft greater than 180.  
  2. An energy conversion device as defined in claim 1, further comprising means for charging a working volume formed between one surface of said piston member and an internal surface of said housing.  
  3. An energy conversion device as defined in claim 2, further comprising a second piston member mounted in tandem with said first piston member on said crankshaft, and wherein said housing includes an internal wall forming two sections, one housing said first piston member and the other housing said second piston member, and wherein said charging means includes a transfer passage extending between said sections and disposed for being open and closed by said first piston member during movement thereof.  
  4. An energy conversion device as defined in claim 3, wherein said charging means includes an intake port, and wherein said first piston member includes a transfer recess in one surface thereof, said transfer recess being positioned to provide fluid communication between said intake port and said transfer passage during displacement of said first piston member from a first position to a second position in its reciprocal movement, said transfer passage terminating in a transfer port in said one section, with said transfer port being positioned to provide fluid communication between said other section and the working volume of said one section during displacement of said first piston member from approximately its second position to approximately its first position in its reciprocal movement.  
  5. An energy conversion device as defined in claim 3, wherein said second piston member is mounted for reciprocal movement in said other section and is disposed for attaining its top dead center position from to rotational displacement of said crankshaft before said first piston member attains its top dead center position during rotation of said crankshaft.  
  6. A two-cycle internal combustion engine comprising a. a housing having a combustion section and a charging section,  
 b. a crankshaft extending through said sections,  
 c. a pair of piston members, each mounted for reciprocal and pivotal movement on an axis which is parallel to an axis of rotation of said crankshaft, with one mounted in said combustion section and the other mounted in said charging section, and  
 d. a pair of connecting rods, each extending between a respective piston member and said crankshaft, said one piston member including a surface having all points thereof equidistant from its pivotal axis and said combustion section including a surface comformably shaped thereto, with said surface of said one piston disposed for slidable sealing engagement with said surface of said combustion section, said one piston member including a transfer recess in said surface thereof, said section including a transfer port and an intake port and an exhaust port in said surface thereof, with said intake port being disposed in fluid communication with said transfer port through said transfer recess in one position of said one piston member and said transfer port being disposed in fluid communication with said exhaust port in another position of said one piston member, said housing including a transfer passage extending from said transfer port to said charging section.  
  7. A two-cycle internal combustion engine as defined in claim 6, wherein said crankshaft includes a pair of crankpins, each connected to a respective one of said connecting rods, and wherein one of said crankpins connected to said other piston member leads the other of said crankpins by from 80 to 130 in the rotational displacement of said crankshaft.  
  8. A two-cycle internal combustion engine as defined in claim 7, wherein said one crankpin leads said other crankpin by approximately 110 in the rotational displacement of said crankshaft.  
 9. An energy conversion device comprising a. a housing;  
 b. a crankshaft extending through said housing;  
 0. a plurality of piston members each mounted for reciprocal and pivotal movement in said housing on a respective one of a plurality of axes parallel to one another and to the axis of rotation of said crankshaft; and  
 d. a plurality of connecting rods each pivotally mounted at one end thereof to a respective one of said piston members and at the other end thereof to said crankshaft; the relative dimensions from the axis of said crankshaft to each axis of rotation of each piston, from each axis of rotation of each piston to the connection of each connecting rod with a respective one of said pistons, of the length of said connecting rods, and of the stroke of each of said pistons providing from a top dead center position to a bottom dead center position of each piston a rotational displacement of said crankshaft greater than 10. An energy conversion device as defined in claim 9, wherein said crankshaft includes at least one crankpin, and wherein at least two of said connecting rods are connected to said crankpin, such that the reciprocal movements of each of a corresponding one of said piston members he in the same plane.  
  11. An energy conversion device as defined in claim 9, wherein said relative dimensions provide from a top dead center position to a bottom dead center position of each piston a rotational displacement of said crankshaft greater than 200.  
  12. An energy conversion device as defined in claim 9, wherein said relative dimensions providefrom a top dead center position to a bottom dead center position of each piston a rotational displacement of said crankshaft equal to approximately 210.