Patent Publication Number: US-2015083084-A1

Title: Friction  reduction and variable compression ratio

Description:
BACKGROUND OF THE INVENTION 
       1 . Field of Invention 
     Internal Combustion engines have been in use for over one hundred years. In the case of common gas and diesel engines, it is known that between 20-25% of fuel power is lost due to the friction force between the piston and the cylinder; this is particularly more evident while the engine is under significant mechanical load. The share of loss due to friction between the piston rings and the cylinder is approximately 3% of fuel power. The reason for the high loss of power due to friction between the piston and the cylinder is the large force which acts on the piston rod. That force has a component perpendicular to cylinder inside wall. Although there are other frictional losses in internal combustion engines, but the said friction between the piston and cylinder is the major frictional loss. Reduction of said friction force will cause greater efficiencies than that of normal engines. 
     On the combustion side, for enhancing the engine performance and efficiency, the ability to change the compression ratio, although not a vitality, has received more attention in recent years. 
     As far as enhancement of combustion and engine efficiency is concerned, this disclosure will be addressing these two concepts. 
     OBJECTIVE OF THE INVENTION 
     The principal objective of this invention is to introduce a new method of drastically reducing the friction force between the piston and the cylinder. In that regard the invention will introduce support mechanisms for piston rods with one degree of freedom and will expand on the concept of piston rod support for the piston rods and crank cams which are introduced in “Behnam Reciprocating Mechanisms”, B. Nedaie, U.S. pending patent application Ser. No. 13/482,993. Furthermore this disclosure shows how the same principle could be applied for piston rods connecting to ordinary crankshafts. For a piston rod with only translational motion, a special connection between the piston and piston rod will be illustrated. In addition to that in order to enhance combustion, a method of changing the compression ratio will be presented. 
    
    
     
       LIST OF FIGURES 
       The disclosure shall be presented by the aid of the following figures: 
         FIG. 1  shows a geometrical presentation of piston rod from “Behnam Reciprocating Mechanisms” supported with roller bearings. 
         FIG. 1   a  shows a three dimensional model of the apparatus said in  FIG. 1 . 
         FIG. 2  shows a geometrical presentation of a piston rod for an ordinary crankshaft being supported with roller bearings. 
         FIG. 2   a  shows a three dimensional model of the apparatus said in  FIG. 2 . 
         FIG. 2   b  shows the geometrical-conceptual illustration of an apparatus for a piston rod being supported by moving cylindrical rollers while the piston is at top dead center position. 
         FIG. 2   c  shows the apparatus said in  FIG. 2   b  after the movement of the piston to bottom dead center position. 
         FIG. 2   d  shows the isometric view of an apparatus for supporting the piston rod with moving rollers in which the piston rod and the moving rollers are furnished with gear teeth. 
         FIG. 2   e  shows the apparatus said in  FIG. 2   d  disassembled. 
         FIG. 2   f  shows section A-A from  FIG. 2   d  (only the portion of the section is shown which holds geared rollers,). 
         FIG. 2   g  shows section A-A shown said in  FIG. 2   f  in isometric view. 
         FIG. 2   h  shows front elevation view of the apparatus said in  FIG. 2   d.    
         FIG. 2   j  shows section B-B shown from  FIG. 2   h.    
         FIG. 2   i  shows section B-B shown in  FIG. 2   j  in isometric view. 
         FIG. 3  shows the top dead center position at the end of compression stroke for an engine with a certain compression ratio. 
         FIG. 4  shows the apparatus said in  FIG. 3  with compression ratio insert substantially moved into the cylinder to decrease top dead center volume and as a result creating higher compression ratio than that of shown for apparatus in  FIG. 3 . 
         FIG. 5  shows the option of having the piston and the piston rod as one solid piece. 
         FIG. 6  shows the option of having the piston and the piston rod as two separate pieces. 
         FIG. 7   a  shows an apparatus for special connection of piston and piston rod such that the piston can have minute movements with respect to the piston rod in any direction perpendicular to the piston central axis. 
         FIG. 7   b  shows the point of connection of piston and piston rod said in  FIG. 7   a  from a different angle enlarged by a scale factor of 2. 
         FIG. 7   c  shows section C-C from  FIG. 7   a  enlarged with scale factor of  2  (only the portion which shows the connection of the piston to piston rod is shown). 
         FIG. 7   d  shows the apparatus said in  FIG. 7   a  disassembled. 
     
    
    
     DESCRIPTION OF THE INVENTION 
     Drastic reduction of friction force between the cylinder and the piston: 
     Considering an ordinary internal combustion engine, as said before the loss of power due to friction between the piston and the cylinder accounts for a large portion of power produced by the fuel. In engines with ordinary crankshafts, the said friction force is directly proportional to the coefficient of friction between the cylinder and the piston, and the normal component of the force (normal to cylinder wall) by which the piston and the piston rod exert against each other. This is because the same force will be exerted by the piston to the cylinder. The said friction force is variable throughout the duration of each stroke mainly because the pressure inside the cylinder chamber changes during a stroke; additionally the piston rod has two degrees of freedom: translation and rotation. Due to the said rotation the magnitude of the said friction force changes as the angle of piston rod with respect to piston central axis changes. 
     For a cam engine which has a piston rod with one degree of motion and in particular an engine with a crank cam suggested in “Behnam Reciprocating Mechanisms”, (U.S. pending patent Ser. No. 13/482,993 by B. Nedaie), the piston rod which is directly connected to the piston, has only one degree of freedom and that degree of freedom is translation along the cylinder&#39;s central axis. As a result if the piston rod is supported by roller bearings, the friction force between piston and cylinder will be almost eliminated. The two  FIGS. 1 &amp; 1   a  show the basic geometrical presentation and a three dimensional model of the concept for said Behnam crank cam  4  respectively (the cylinder, piston and valves are not numbered). 
     The piston rod  1  (the piston and piston rod could be one solid piece) is supported by roller bearings  2  which are held by the stationary support  3 ; the assembly of the stationary support  3  and the roller bearings  2  (in this case  6  roller bearings) is shown by numeral  2 A (numeral  2 A is shown in a simple presentation to illustrate the concept). Said numeral  2 A is fixed to the engine block (engine block not shown); also the crankshaft&#39;s central shaft is mounted as normally a crankshaft is held in the engine block. The piston rod  1  must have flat surfaces where it is in contact with the roller bearings  2 . As a result of the geometry of this apparatus, the piston does not exert a significant force against the cylinder and the said force will be reduced drastically. The number of roller bearings on either side of piston rod  1  must be at least two. In the apparatus shown in  FIGS. 1 &amp; 1   a  there are three roller bearings  2  on either side of piston rod  1 . 
     Referring to  FIGS. 2 &amp; 2   a , likewise the same concept could be applied to ordinary crankshafts by having a connection link  5  Numeral  6  is an ordinary crankshaft which is connected to piston rod  16  by connection link  5 . In this apparatus the friction force between the piston and the cylinder will be also reduced drastically because of similar reasons mentioned for apparatus presented in  FIGS. 1 &amp; 1   a.  It is understood that connection link  5  has two degrees of freedom where the piston rod  16  has only one degree of freedom; that degree of freedom is translation along the piston central axis. 
     For both apparatuses shown in  FIGS. 1   a  &amp;  2   a  the piston rod and the piston can be a solid piece together or be separated and connected to each other as they normally are with a pivot point at the point of contact of piston and the piston rod. However in both cases the rod which is connected to the piston has only one degree of freedom.  FIGS. 5 &amp; 6  show the two different scenarios. In  FIG. 5  the piston and the piston rod are one solid piece and shown by numeral  12  (the cylinder and the crankshaft not shown), said piston rod  12  is supported by numeral  2 A. In  FIG. 6  the connection of a piston and piston rod is shown (the cylinder and the crankshaft not shown). The piston  13  and piston rod  14  are two separate parts and are connected at point  15 . Said piston rod  14  is supported by piston rod support assembly  2 A. Both piston rods  12  and  14  in  FIGS. 5 &amp; 6  have only one degree of freedom and that is translation along the central axis of the piston. 
     The same result might be achieved with other similar arrangements. For example for each roller bearing, two ball bearings holding a roller could be used. Another scenario is supporting the piston rod from two directions instead of one direction as shown in this disclosure. But in mechanisms shown in  FIGS. 2 &amp; 2   a  and other similar configurations the central axis of each of the roller or ball bearings is stationary. That is the said central axes have no movement with respect to engine block. 
     Since the forces acting on the stationary ball or roller bearings supporting the piston rod mentioned so far will be tremendous, particularly when the engine is under great mechanical load at high RPM, therefore as a result the size of these bearings might be so large that it might not be practical to implement stationary roller or ball bearings in practice. Therefore it is important to consider the option of supporting the piston rod with moving cylindrical rollers.  FIGS. 2   b  to  2   j  ( 9  figures) show the drawings associated with this concept.  FIGS. 2   b  and  2   c  show the basic geometrical concept of moving rollers and  FIGS. 2   d  to  2   j  are associated with the moving rollers furnished with gear teeth. 
     In  FIGS. 2   b  &amp;  2   c  ( 2  figures) the basic geometrical illustration of the concept of moving rollers with two different positions of the piston are illustrated. In  FIG. 2   b , inside the engine block  19 , the piston  24  is connected to the piston rod  20  and the said piston rod  20  is supported by quantity of  6  moving cylindrical rollers  21 ; the cylindrical moving rollers  21  are held tight between the piston rod  20  and stationary support  19   a;  nuts  19   b  allow adjusting and fastening the stationary support  19   a  to the engine block  19 . On either sides of the piston rod  20 , there are  3  moving cylindrical rollers  21 . The moving cylindrical rollers  21  are in close contact with the piston rod  20  and the stationary support  19   a.  As mentioned before for the case of stationary roller bearings, in this case as well, a minimum of  2  moving cylindrical rollers  21  are needed on either sides of piston rod  20 . In  FIG. 2   b  the position of the piston  24  is at top dead center position. In  FIG. 2   c  the same apparatus is shown as in  FIG. 2   b  except the piston  24  and piston rod  20  have moved to bottom dead center position. In both  FIGS. 2   b  &amp;  2   c  the center of one of the moving cylindrical rollers  21  is shown by numeral  23  and an edge from the stationary support  19   a  is shown by numeral  22  for reference datum. By comparing the two  FIGS. 2   b  &amp;  2   c,  it is clear that as the piston rod  20  has moved form top dead center to bottom dead center position, the center point shown by numeral  23  has changed its position with respect to edge  22 . Another word as the piston rod  20  moves cylindrical rollers  21  roll in the same direction and the central axis of the each of the moving cylindrical rollers  21  translated in the same direction. 
     In order to use moving cylindrical rollers  21  for the purpose of supporting the piston rod  20 , it must be realized that first of all the central axes of rotation of these moving rollers  21  must have no motion with respect to each other. That is during the operation of the engine the distance between each two rollers must remain the same at all times. Secondly there must be no slippage at the area of contact between the surfaces of the moving cylindrical roller  21  and the piston rod  20  and the stationary support  19   a.  Such slippages can severe the operation of the engine and additionally may result in frictional losses. 
     In order to address the said two points in the previous paragraph, each of the moving cylindrical rollers and the piston rod could be furnished with gear teeth.  FIGS. 2   d  to  2   j  ( 7  figures) are associated with this concept. In  FIG. 2   d  an apparatus is shown in isometric view for supporting the piston rod with moving rollers in which the piston rod and the moving rollers are furnished with gear teeth; in this figure half of engine block is removed to have inside mechanism visible. In  FIG. 2   e  the same apparatus is shown in disassembled mode.  FIG. 2   f  shows section A-A from  FIG. 2   d  which is through the center of the piston rod and the center of the geared rollers.  FIG. 2   g  shows the isometric view of the same section A-A said in  FIG. 2   f . In  FIG. 2   h  the front elevation view of the apparatus in  FIG. 2   d  is shown.  FIG. 2   i  is the section B-B from  FIG. 2   h  and  FIG. 2   j  is the same section shown in  FIG. 2   i  in isometric view. 
     The components and their function are as follows: 
     Piston  25 : Piston  25  is inside the cylinder of engine block  27  and is connected to piston rod  26 ; the piston  25  and the piston rod  26  could be two separate pieces or one solid piece. Piston  25  has one degree of motion and that is translation along the central axis of the corresponding cylinder in engine block  27 . 
     Piston rod  26 : Piston rod  26  has only one degree of motion and that is translation along the central axis of the corresponding cylinder; unlike ordinary piston rods, it does not have any rotational motion. It is connected to piston  25  from one end and from the opposite end is connected to either a cam shaft as already shown in  FIGS. 1 &amp; 1   a,  or is connected by a link to an ordinary crankshaft as was shown in  FIGS. 2 &amp; 2   a.  The cross-section of piston rod  26  is preferably rectangular and as shown has geared racks on two opposite surfaces which accommodate the gear teeth from the geared rollers  30 . Additionally on either side of its geared portion, it has a flat surface to have contact with the cylindrical surfaces of the rollers  30 . The large force exerted by the piston rod  26  to geared roller  30  is transferred by the said flat section of the piston rod  26  and not the geared portion. The purpose of the gear rack of the piston rod  26  is just to avoid slippage between the surfaces of the geared rollers  30 , piston rod  26  and stationary support  32 . 
     Engine block  27 : Engine block  27  is shown only partially in a simple way to address the features discussed in this invention; the stationary support  32  is fastened to the engine block  27  by nuts  33 . 
     Triple pin  28 : Triple pin  28  has three pins and each pin goes inside the hole of geared roller  30  such that the corresponding geared roller  30  is free to rotate about the central axis of the said pin. Triple pin  28  has one degree of freedom and that motion is translation along the direction of the central axis of the cylinder. 
     Flat end  29 : The purpose of Flat end  29  is to secure geared rollers  30  and stop the geared rollers  30  from any translation motion along the direction of its axis of rotation. Flat end  29  has one degree of freedom and that motion is translation along the direction of the central axis of the cylinder. 
     Geared roller  30 : The geared roller  30  has a hole along its central axis and is freely rotatable about its central axis and each geared roller  30  is freely rotating about of the pins of triple pin  28 . It has a gear section at the center and two cylindrical surfaces on either side of the said geared section. The large force exerted by the piston rod  26  to geared roller  30  is transferred via this cylindrical section (and not the geared portion) of the geared roller  30  to the stationary support  32 . 
     Geared roller assembly  31 : The geared roller assembly is comprised of three geared rollers  30 , a triple pin  28  and a flat end  29 . However the minimum number of geared rollers needed for each assembly  31  is two geared roller  30 . Each pin of the triple pin  28  holds one geared roller  30  and the said geared roller  30  is free to rotate about the central axis of the corresponding pin of the said triple pin  28 . The flat end  29  secures the geared rollers  30  in place. In  FIG. 2   e  one geared roller assembly  31  is shown in assembled mode and numbered as numeral  31  and the second geared roller assembly  31  is shown in disassembled mode and every individual component is numbered. 
     Stationary support  32 : the stationary support  32  is fastened to the engine block  27  by nuts  33  and has no motion with respect to engine block  27 . Although in these illustrations the stationary support  32  is not furnished with gear teeth, however it is possible to do so. 
     Nuts  33 : These nuts  33  allow adjustable fastening of Stationary support  32  to the engine block  27 . 
     For all the mechanisms discussed so far, it must be noted that the illustrated piston rod support will have no or very little effect on the friction between the piston rings (rings are not shown in any of the figures) and the cylinder. That portion of friction loss due to friction between the piston rings and the cylinder may remain the same. 
     It is obvious that the concept for supporting the piston rod for reduction of the friction force between the piston and the cylinder will result in smaller than normal cooling system for cooling the engine block. That is the size of radiator and cooling system will be reduced drastically to the extent that in some cases only air cooling may suffice. This is because the major reason for an engine block to heat up is the contribution of the said friction force between the piston and cylinder and not the heat transfer from the combustion. Likewise because of drastic reduction of the friction between the piston and the cylinder, the size of the starter mechanism and the power required to start the engine will reduce considerably. 
     Special Connection of Piston to Piston Rod: 
     Due to the nature of the operation of a piston rod with only one degree of freedom (that degree of freedom being translation along the direction of pistons central axis), there might be a need for a special connection between the piston and the piston rod. In that regard reference will be made to  FIGS. 7   a,    7   b,    7   c  and  7   d  ( 4  figures). They show an apparatus for a special connection between the piston and the piston rod, where the piston rod has only one degree of motion. In  FIG. 7   a  the isometric view of an apparatus is shown with a piston rod which has one degree of motion and that motion is translation along the central axis of the cylinder; the apparatus provides a special connection between the piston and the piston rod such that the piston can have minute movements with respect to the piston rod in any direction perpendicular to the central axis of the piston.  FIG. 7   b  shows a different isometric view of only the connection between the piston  17  and piston rod  16 , enlarged by a scale factor of  2 .  FIG. 7   c  shows the upper portion of section C-C from  FIG. 7   a  enlarged by a scale factor of  2 .  FIG. 7   d  shows the apparatus in  FIG. 7   a  in disassembled mode. 
     Ideally there are three center lines which must be aligned. One is the central axis of the cylinder (the cylinder is not shown in these four figures); the second is the central axis of the piston  17  (numeral  17   a ) and the third is the centerline of the piston rod  16  (numeral  16   a ). In  FIGS. 7   c  and  7   d  the central axes piston  17  and piston rod  16  are shown). The centerline of the piston rod will be at the middle of the two sets of the roller bearings  2  which are parts of the piston rod support which was already referred to as numeral  2 A. Since the alignment of said central axes might be difficult due to manufacturing defects, other methods of connection of the piston and the piston rod might be needed in order to allow minute misalignments between the center line of the piston  17  (numeral  17   a ) and the central axis of the piston rod  16  (numeral  16   a ). That is basically allowing the piston  17  to have minute movements with respect to the piston rod  16  in any direction perpendicular to its central axis (numeral  17   a ). 
     This is because in the case of a piston rod with one degree of motion, if the connection of the piston to piston rod is a normal connection as it is in ordinary engines, manufacturing defects may cause large forces acting on the piston in the direction perpendicular to the piston axis and force the piston against the cylinder wall. In fact it was one of the main intentions of the invention to eliminate the force which the piston exerts to the cylinder. It is important that the piston must move in the cylinder as freely as possible in order to eliminate the associated frictional force. 
     In  FIG. 7   c  the section C-C is shown; the eccentricity between the center line of piston rod  16  (numeral  16   a ) and the central axis of piston  17  (numeral  17   a ) is clearly shown. Since piston rod  16  is held firm by roller bearing support  2 A, the piston  17 &#39;s central axis shown by numeral  17   a  can have slight misalignments with that of piston rod  16 &#39;s centerline which is shown by numeral  16   a.  This is due to the nature of the connection of piston rod  16  and piston  17 . While piston  17  can not have any motion with respect to piston rod  16  in the direction parallel to central axis of the piston  17  (that central axis is numeral  17   a ), said piston  17  can have small movements with respect to piston rod  16  in any direction perpendicular to the central axis of the piston  17  (that central  17   a ). 
     Variable Compression Ratio: 
     This disclosure suggests that in order to change the compression ratio for a given internal combustion engine, an insert could be pushed into or pulled out of the cylinder head in order to control the compression ratio.  FIGS. 3 &amp; 4  are associated with this concept. The compression ratio will increase as the insert is pushed into the cylinder upper chamber (head cylinder). The vice versa is also true; that is as the insert is pulled out of the head cylinder the compression ratio decreases. The gaps between parts in these figures have been exaggerated in order to distinguish the parts in said two figures. 
     In  FIG. 3  a typical piston  8  is shown inside cylinder  7  (the cylinder and the cylinder head are shown as one piece) at top dead center position at the end of compression stroke. The certain amount of volume between the piston  8  and the cylinder  7 &#39;s head, corresponds to the volume of the compressed air fuel mixture under compression at the top dead center position. The said volume is shown by numeral  10  (numeral  10  is the hatched area between cylinder head and the piston). Notice that the compression ratio insert  9  is substantially away from piston  8 &#39;s top surface. 
       FIG. 4  shows the same apparatus as in  FIG. 3  at the same top dead center position except the compression ratio insert  9  is substantially moved into the cylinder chamber. In  FIG. 4  the volume of the air fuel mixture at top dead center is shown by numeral  11  (numeral  11  is the densely hatched area between cylinder head and the piston). Comparing  FIGS. 4 &amp; 3 , one can see that the volume represented by numeral  11  in  FIG. 4  is smaller than that of numeral  10  in  FIG. 3 . As a result the compression ratio of apparatus shown in  FIG. 4  is higher than that of  FIG. 3 . It is obvious that the lengths of all the strokes for both apparatuses in these two figures are the same and the volume of the space that the compression ratio insert  9  will take is relatively insignificant compare to that of the intake volume. However the volume of compression ratio insert  9  is significant compare to the volume of the gas air mixture at top dead center position (that is numerals  10  or  11 ) and that is the reason that the change in the compression ratio occurs as the compression ratio insert  9  is pushed into or pulled out of cylinder chamber. It must also be noted that the sealing between the compression ratio insert  9  and head of cylinder  7  must be tight so that no substantial compressed gas can escape out of the cylinder chamber. 
     It is not the intention of this invention to address the methods of moving the compression ratio insert  9  into and out of the cylinder chamber; that might be achieved by mechanical, hydraulic or electrical servo motor mechanisms with appropriate controls. Nor is the intention of the invention to suggest any means or methods of control of the said action as to how often it must happen or for how long the insert  9  must stay at a certain position. It is primarily the methodology of changing the compression ratio which is under consideration. 
     In the figures shown in this disclosure, in each figure some parts might have not been shown and/or numbered; this is because only the concepts under consideration were to be addressed. As a result a detailed presentation of the internal combustion engine in these figures was avoided since it was not necessary. 
     The description given in this disclosure, it is obvious that the same may be varied in many other similar ways and methods. Such variations are not to be considered as departure from the core philosophy of the invented mechanisms. All such variations and modifications which are obvious to those skilled in the art are considered to be within the scope of this disclosure and embodied in the claims made.