Patent Publication Number: US-6666656-B2

Title: Compressor apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation-in-part of patent application Ser. No. 09/976,816, filed Oct. 12, 2001 for SHUTTLE PISTON ASSEMBLY WITH DYNAMIC VALVE by Hans-Georg G. Pressel and incorporated by reference herein. 
    
    
     BACKGROUND AND FIELD OF INVENTION 
     This invention relates to compressors; and more particularly relates to a novel and improved method and means for regulating the intake and exhaust of air or other gaseous fluid into and from a compressor in a simplified and efficient manner. 
     Standard compressors typically operate with suction and discharge valves installed in a cylinder head which impose severe size limitations on the valves and on the amount of fluid that can be drawn in and discharged in each cycle. A related problem has to do with the time constraints imposed upon maintaining the intake valve in an open position over the maximum period of time during the intake stroke and the ability to draw in the maximum amount of air during the suction stroke. 
     In the past, it has been proposed to utilize a compressor having a crankcase in combination with a cylinder and cylinder head and in such a way as to direct the intake air into the crankcase prior to forcing it into the cylinder. Representative patents are U.S. Pat. Nos. 209,673 to Grillenberger; 1,109,154 to Thomas; 1,445,073 to Corpi and 5,613,837 to Conishi. To my knowledge, however, no one has successfully devised an air compressor which is capable of operating at maximum efficiency over the greater portion of the suction and discharge cycles. In particular, there is a need for a compressor which will make maximum utilization of a crankshaft over the entire intake stroke as well as to draw in-the maximum amount of pre-pressurized air for discharge over each discharge stroke. In so doing, it is highly desirable to control the timing and duration of opening and closing of an intake port in the crankcase during each intake and compression stroke, respectively, in close coordination with rotation of the crankshaft and reciprocation of the piston. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide for a novel and improved compressor. 
     It is another object of the present invention to provide for a method and means for increasing the volumetric efficiency of an air compressor in a highly simplified and efficient manner. 
     It is a further object of the present invention to provide for a novel and improved method and means for pre-pressurizing air to be drawn into one or more cylinders of an air compressor and for regulating the opening and closing of an intake port which supplies the pre-pressurized air to the crankcase. 
     It is a still further object of the present invention to provide for a novel and improved method of controlling the duration of opening and closing of an intake port leading into a crankcase chamber in close coordination with the suction and discharge stroke of the piston. 
     In accordance with the present invention, in a compressor of the type having a crankcase, a cylinder communicating with the crankcase through an outer peripheral wall and having an exhaust valve at one end, the combination therewith comprises a fluid intake port communicating with the crankcase through one end of the chamber substantially diametrically opposed to the cylinder, a piston reciprocal in the cylinder having an intake valve, a crankshaft mounted for rotation in the crankcase including gate control means for opening and closing the intake port through each revolution of the crankshaft, the gate control means being operative in response to rotation of the crankshaft through each revolution to start to close the intake port prior to advancement of the piston to one end of its stroke adjacent to the exhaust valve and to start to open the intake port prior to advancement of the piston to an opposite end of its stroke away from the exhaust valve. Preferably, the intake valve is of the leaflet type which is capable of rapidly opening and closing in response to changes in pressure and piston inertia, and the gate control means is operative to open the intake port in the crankcase through at least 180° of each revolution of the crankshaft. 
     There has been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will form the subject matter of the claims appended hereto. In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a sectional exploded view of a preferred form of compressor in accordance with the present invention illustrating the piston at the end of its suction stroke; 
     FIG. 2 is another sectional exploded view of the preferred form shown in FIG. 1 illustrating movement of the piston through the cylinder; 
     FIG. 3 is a somewhat perspective view with portions broken away of the preferred form of compressor shown in FIGS. 1 and 2; 
     FIG. 4 is an exploded view of the moving parts of the compressor shown in relation to the stationary intake manifold in the crankcase; 
     FIG. 5 is another exploded view in perspective form of the elements shown in FIG. 4; 
     FIGS. 6 to  9  are sectional views illustrating the sequence of movement of the compressor crankshaft and piston through each revolution in accordance with the present invention; 
     FIG. 10 is a sectional view with portions broken away of a two-cylinder compressor in accordance with the present invention; and 
     FIG. 11 is a sectional view of a standard compressor. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
     Referring in more detail to the drawings, there is shown by way of illustrative example in FIG. 11 a conventional compressor A which is made up of a crankcase C in which a crankshaft D rotates and, in turn, reciprocates a piston P through cylinder bore B. A cylinder head H at one end of the cylinder B contains an intake valve V 1  and a discharge valve V 2 . In a typical operation, as the crankshaft D is rotated by any suitable motor, the piston P is reciprocated through a suction stroke away from the cylinder head H to induce air into the cylinder, followed by a discharge stroke toward the cylinder head H to pressurize the air and force it through the discharge valve V 2 . In accordance with the present invention, it is possible to greatly enhance the capacity, efficiency and performance of the standard compressor by substitution of a novel and improved crankshaft assembly and piston for the existing crankshaft and piston described, modifying the cylinder head to contain only the discharge valve in place of the valve V 2  and placement of a dynamic intake valve in the piston in place of the valve V 1 . The crankcase is modified to include an intake manifold for the introduction of air into the crankcase on the suction stroke, and the crankcase is modified to include a gate control member to coordinate the opening and closing of the intake manifold with the reciprocation of the piston through its suction and discharge strokes. 
     In the preferred form of invention shown in FIGS. 1 to  9 , a crankcase  10  of hollow circular configuration has an outer peripheral wall  12  which is bounded by opposite flat side walls  13  and  14 . An intake manifold  16  extends through the wall  13  and terminates in an intake port  18  which is flush with a circular intake plate  20 . The intake plate  20  is firmly anchored to the wall  13  by the intake manifold  16  as well as one or more support studs  22  so as to be in interspaced parallel relation to the side wall  13 . Circumferentially spaced radial grooves  24  are disposed in the surface of the plate  20 . 
     A crankshaft  25  includes a drive sleeve  26  which is keyed for rotation on output shaft  27  of a motor M. The crankshaft  25  is in the form of a generally circular plate having a drive pin  32  in offset relation to the drive sleeve  26  for insertion through a bearing  34  in one end  35  of a connecting rod  36  so as to mount the connecting rod in journaled relation to the drive pin  32 . 
     An important feature of the present invention resides in a control gate  40  which is in the form of an annular disk or plate of semi-circular configuration mounted in spaced parallel relation to the crankshaft  25  by pin members  42  which extend at circumferentially spaced intervals from the plate  40  and are slidable in bores  41  in the crankshaft  25  so that the gate  40  is fixed for rotation with the crank. Compression springs  44  are disposed on the pins  42  to yieldingly urge the gate  40  into sealed engagement with the intake plate  20 . The contacting surfaces of the plate  20  and gate  40  are composed of a low friction material and the gate  40  is aligned to traverse the intake port  18  so as to close the intake port for a predetermined time interval and number of degrees of each revolution of the crank. 
     A cylinder bore  46  extends radially from a portion of the peripheral wall  12  of the crankcase so as to be in open communication with the crankcase. The cylinder bore  46  is preferably offset with respect to the crankcase in order to reduce the connecting rod angle during the compression stroke in a manner to be described. A piston  48  at the free end of the connecting rod opposite to the drive pin is slidable in sealed relation to the cylinder bore  46  and contains a dynamic intake valve  50  to be hereinafter described in more detail. A cylinder head  52  is mounted on the open end of the cylinder bore  46  opposite to the crankcase including a passage  53  in which a exhaust valve  54  is positioned for the controlled discharge of compressed air through the cylinder. The exhaust valve  54  corresponds to the discharge or exhaust valve described in my hereinbefore referred to application for patent for SHUTTLE PISTON ASSEMBLY WITH DYNAMIC VALVE which is incorporated by reference herein. 
     A filler block  56  is mounted in the crankcase chamber to regulate the volumetric ratio between the crankcase  10  and cylinder bore  46 . An additional filler block may be positioned as at  59  in order to further reduce the open space in the crankcase to achieve a predetermined volumetric ratio with the cylinder bore  46 . The filler blocks  56  and  59  may be composed of any non-porous lightweight material, such as, a plastic foam and is particularly useful in retrofitting existing or standard compressors for use in accordance with the present invention. Nevertheless, it will be evident that the same volumetric ratio may be achieved in dimensioning the chamber within the crankcase to be at the desired volume or size in relation to the cylinder bore so as to achieve a particular volumetric ratio. It is important to keep the crankcase cavity as small as possible for maximum pre-compression of the air entering the crankcase prior to discharge through the cylinder and it is therefore desirable that the maximum space available in the crankcase be less than that in the cylinder bore  46 . 
     Preferably, the volumetric ratio between a crankcase and cylinder is in the range of 0.85 to 1.0. In addition, it is desirable to incorporate a slight offset between the inner connecting end of the cylinder bore  46  to the peripheral wall  12  of the crankcase so as to reduce the connecting rod angle as it advances through the cylinder bore  46  and thereby reduces the torque and power required. Most of the power is required in the discharge cycle when the compressor is building up pressure, and the greater the connecting rod angle the more torque that is needed to drive the compressor. The cylinder offset as described avoids the necessity of lengthening the connecting rod and cylinder to reduce the connecting rod angle. 
     In the preferred form, the piston head  48  is connected in fixed relation to the free end of the connecting rod  36 , and the dynamic intake valve  50  is incorporated into the piston head  48  in the manner described in my hereinbefore referred to co-pending application for patent Ser. No. 09/976,816. Specifically, the piston  48  is made up of an annular disk  48 ′ having a circumferential groove  57  in outer peripheral edge  58 . The edge  58  is of convex configuration so that the cylinder bore  46  will remain on a tangent to the edge  58  notwithstanding movement of the piston head  48  away from the longitudinal axis of the cylinder bore  46  as it is reciprocated. The groove  57  is dimensioned for insertion of a seal  77  and backing member  78  behind the seal. A radially inner wall  60  of the disk  48 ′ tapers into a shoulder  62  which is united with an enlarged end  64  of the connecting rod  36 . A valve seat  65  is mounted on the shoulder  62  and has kidney-shaped ports  66 , and a leaflet valve member  70  is mounted at its center to the valve seat  65  by a rivet  72 . The valve  70  has leaflet portions  74  which are free to flex away from the center portion or rivet  72  as the piston moves away from its associated cylinder head  52  into abutting relation to a limit stop  74 . 
     The mass of the leaflet portions  70  is regulated to match the inertia of the piston  48  and to cause the leaflet portion  70  to snap open instantly when the piston  48  starts to move away from the cylinder head  52 . There is a limited distance that the piston  48  must travel away from the exhaust valve  54  before atmospheric pressure overcomes the negative pressure in the cylinder forcing the intake valve  50  open. By controlling the mass of the leaflet portions  70  at their greatest distance from the flex point, it is possible to cause the valve  50  to snap open as soon as the piston  48  moves away from the exhaust valve  54 . This increases the time of opening of the valve  50  and retains it open over a longer time interval during its intake stroke thereby substantially increasing compressor efficiency and performance. 
     At the end of each intake stroke and compression stroke and, since the piston will have moved a limited distance of the intake stroke to create a large enough void to force the intake valve open, could easily amount to between 10° to 25° of the total crankshaft revolution. However, as the piston  48  travels away from the exhaust valve  54 , it increases in speed and reaches maximum velocity when the crankshaft reaches the 90° rotating position. At that point, the piston head  48  will draw the majority of the air from the crankcase. As the crankshaft reaches the next 180° position or end of the stroke, the piston  48  will have slowed down and become static so that little or no air is drawn from the crankcase. Again, the failure to draw air into the cylinder near the top dead center (TDC) or bottom dead center (BDC) would normally account for a waste of 10° to 25° of crankshaft rotation at the end of each intake and compression stroke. However, the total loss of 20° to 50° of crankshaft rotation can be offset by controlling the opening and closing of the intake port  18  without depending upon the piston position and the created void in relation to the crankshaft; also, the intake port  18  can be kept open for greater than 180° of the crankshaft revolution thereby filling the crankcase with a high volume of air, such as, by opening the intake port  18  28° before BDC and closing the intake port  18  25° to 30° before TDC. 
     The dynamic intake valve  50  controls the air pressure required to open and close the valve  50  thereby sacrificing as little energy as possible to overcome the air pressure against the leaflets  74 . The lesser the force required to open and close the valve  50 , the greater efficiency is achieved, since the valve  50  opens earlier in the suction cycle. This can be determined by measuring the negative pressure or suction required in the cylinder bore  46  and timing the opening of the valve  50  in response to the vacuum created. This vacuum is created as the piston  48  moves away from the cylinder head  52  in the suction stroke and increases the negative pressure until the pre-pressurized crankcase air pressure overcomes the dynamic valve leaflet tension to open and fill the cylinder bore  46 . The distance that the piston  48  must travel to produce enough negative pressure to open the valve  50  in relation to the total stroke can be expressed in degrees of crankshaft rotation and can be calculated in real time. 
     The gate control member  40  regulates opening and closing of the intake port  18 , and the intake port  18  is designed to permit the greatest volume of air possible to enter the crankcase chamber at a relatively low air velocity and high air pressure. Thus, as the piston  48  advances toward the cylinder head at  52 , air is drawn through the intake port  18  into the crankcase. The gate control  40  rotates with the crankshaft  25  and is so constructed and arranged, by reference to FIGS. 6 to  9 , that as the piston  48  reaches the end of its intake stroke, the leading edge of the gate control  40  will start to close the intake port  18 . As the piston  48  travels away from the cylinder head  52 , the intake port  18  is closed and the air in the crankcase is compressed then forced through the dynamic intake valve  50  so as to fill the cylinder  46  with the compressed air. As the piston  48  travels away from the cylinder head  52  it will increase in speed and reach the highest velocity when the crankshaft reaches the 90° rotating position so as to draw the majority of the air through the intake valve  50  at that point. On the other hand, as the crankshaft  25  reaches the 180° rotating position, as shown in FIG. 8, the piston  48  will have slowed down and become relatively static at that position. As stated earlier, normally, the failure to draw air into the cylinder  46  near the top dead center (TDC) or bottom dead center (BDC) of the piston position can account for a waste of 10° to 25° of crankshaft rotation at each position. However, with the gate control member  40  it is possible to control and time the opening and closing of the intake port  18  without depending on the position of the piston  48  in relation to the crankshaft  25  and control the timing only with the position of the crankshaft  25 . For example, it is possible to gain as much as 56° of the crankshaft revolution in traversing from 35° before TDC to 28° after TDC; and to increase the opening time of the intake port  18  up to 236° of the crankshaft revolution thereby filling the crankcase with a high volume of air which is then forced into the cylinder bore  46  through the dynamic intake valve  50 . This is partially attributable to opening of the intake port  18  28° before piston BDC and closing the intake port  18  35° before piston TDC, bearing in mind that the piston  48  is already cycling from the suction stroke into the compression stroke and air is still entering the crankcase because of the pressure build-up in the intake manifold. 
     From the foregoing, it is not necessary to depend upon the piston  48  to produce the negative pressure to open the dynamic intake valve  50  but instead time the opening of the intake port  18  to take advantage of the build-up in pressure of the air which accumulates in the intake manifold  16  as the piston advances through its intake stroke. In this way, as the piston and its connecting rod advance through BDC, where normally little or no air is drawn into the crankcase, the pressure build-up of air in the intake manifold  16  will more than compensate for the normally dead period of the cycle and almost double the cylinder filling time from approximately 120° to 140° to 235° to 245° of the crankshaft revolution. In short, closing the intake port  18  on the order of 35° before piston TDC, as shown in FIG. 6, completing closure of the port on the order of 28° after TDC, and opening the intake port  18  on the order of 35° before piston BDC, as shown in FIG. 8, can result in as much as 29% improvement in performance for the average compressor which is retrofitted in accordance with the present invention. 
     It will be apparent that the air flow through the intake manifold varies with compressor rpms, the diameter and length of the intake manifold and the diameter of the dynamic intake valve  50 . The higher the compressor rpms with respect to a small diameter intake manifold and intake valve the higher the air velocity through the manifold and the lower the air pressure. It is therefore important to install the largest intake manifold and intake valve possible to reduce the air velocity and increase the pressure so as to increase the amount of air drawn into the crankcase during each intake stroke. 
     DETAILED DESCRIPTION OF MODIFIED FORM OF INVENTION 
     The advantages and features of the single cylinder compressor described can be incorporated into a multi-cylinder compressor as well. For example, as illustrated in FIG. 10, a crankcase is divided into a pair of crankcase chambers  90  and  91  and cylinders  92  and  93 , respectively, by a common partition  94 . The partition has an intake manifold  95  leading into intake ports  96  communicating with each respective chamber  90  and  91 . There is a crankshaft assembly  98  in each chamber  90  and  91  wherein each crankshaft assembly  98  has dual crankshafts  100  flanking a connecting rod  36 ′ for a piston  48 ′, like parts being correspondingly enumerated with prime numerals to those of the preferred form, including control gate  40 ′ which advances across each intake port  96 . A common output or drive shaft  102  from a motor, not shown, is keyed for rotation of the crankshafts  100 . Also, a common cylinder head  104  is provided for a pair of exhaust valves  54 ′ at the top of each cylinder  92  and  93 . 
     In operation, the crankshafts  100  are mounted in 180° out-of-phase relation with respect to one another so that as one is undergoing its intake stroke the other will undergo its discharge stroke and counterbalance one another in undergoing high speed rotation as well as to successively draw air from the intake manifold  95  through a respective intake port  96 . 
     From the foregoing, the efficiency and performance of standard air compressors of the type having a crankcase and cylinder can be greatly enhanced by controlling both the timing and duration of opening and closing of an intake manifold with a gate control member on a crankshaft in close coordination with the size of the manifold, the volumetric ratio between the crankcase and cylinder and length of piston stroke through the cylinder. It is therefore to be understood that while preferred and modified forms of invention are herein set forth and described the above and other modifications may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and reasonable equivalents thereof.