Patent Publication Number: US-6702557-B2

Title: Valve assembly prohibiting re-expansion of residual fluid

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a fluid compressing apparatus, and more particularly, to a fluid compressing apparatus for discharging the fluid by a compressing or pumping action utilizing a linear reciprocating movement of a piston. 
     2. Description of the Related Art 
     A typical example of a conventional fluid compressing apparatus is shown in FIGS. 1 and 2, which will be described briefly below. 
     FIGS. 1 and 2 are sectional views that schematically show the structure and operation of the conventional fluid compressing apparatus. The reference numeral  10  indicates a cylinder block,  20  a piston,  30  a valve plate and  40  a cylinder head. 
     As shown in FIGS. 1 and 2, the cylinder block  10  has a cylinder bore  11  of a predetermined diameter that penetrates through the cylinder block  10  in a lengthwise or longitudinal direction. The piston  20  is movably mounted in the cylinder bore  11  of the cylinder block  10  so as to be capable of reciprocal action, and the valve plate  30  is disposed in the cylinder block  10 . The valve plate  30  has fluid suction/discharge ports  31  and  32  formed therein, and suction/discharge valves  33  and  34  (shown in phantom), that can open and cover the fluid suction/discharge ports  31  and  32 . The cylinder head  40  is disposed in the cylinder block  10  toward the longitudinal side adjacent the valve plate  30 , and the cylinder head  40  has fluid suction/discharge chambers  41  and  42  respectively interconnecting with the fluid suction/discharge ports  31  and  32  of the valve plate  30 . The cylinder head  40  is connected to fluid suction/discharge manifolds  43  and  44  that are respectively interconnected with the fluid suction/discharge chambers  41  and  42  of the cylinder head  40 . 
     In the conventional fluid compressing apparatus constructed as described above, and illustrated in FIGS. 1 and 2, a driving force transmitted from a piston driving source (not shown), causes the piston  20  to reciprocate within the cylinder bore  11  of the cylinder block  10 , thereby causing the fluid to be drawn in, compressed and discharged. 
     Additionally, as the piston  20  moves from the top dead end point T (FIG. 1) to the bottom dead end point B (FIG. 2) of the cylinder bore  11 , due to the different pressures in and out of the cylinder bore  11 , the suction valve  33  opens the suction port  31  of the valve plate  30  (as shown in phantom in FIG.  2 ), and accordingly, the fluid is drawn into the cylinder bore of the cylinder block  10  sequentially through the suction manifold  43 , the suction chamber  41  of the cylinder head  40  and the suction port  31  of the valve plate  30 . At this time, the pressure in the discharge chamber  42  of the cylinder head  40  is higher than the pressure in the cylinder bore  11  so that the discharge valve  34  maintains the discharge port  32  closed. 
     Meanwhile, as the piston  20  is returned from the bottom dead end point B (FIG. 2) to the top dead end point T (FIG.  1 ), the fluid in the cylinder bore  11  is gradually compressed. Finally, when the piston  20  reaches the top dead end point T, as shown in FIG. 1, the pressure in the cylinder bore  11  becomes higher than the pressure in the discharge chamber  42  of the cylinder head  40 , and accordingly, as shown in phantom in FIG. 1, the discharge valve  34  opens the discharge port  32  of the valve plate  30 , and the compressed fluid is discharged through the discharge port  32  of the valve plate  30 , the discharge chamber  42  of the cylinder head  40  and the discharge manifold  44 . At this time, the pressure in the suction chamber  41  is lower than the pressure in the cylinder bore  11 , and thus, the suction valve  33  maintains the suction port  31  closed. 
     Then, when the piston  20  moves back to the bottom dead end point B, the suction port  31  is opened by the suction valve  33 , whereas the discharge port  32  is closed by the discharge valve  34 . As a result, the fluid is drawn into the bore  11 . Then as the piston  20  is moved to the top dead end point T, the drawn air is compressed and then discharged through the discharge port  32 . As this reciprocating movement of the piston  20  repeats, the compression and discharge of the fluid also repeats the cycle described above. 
     In the conventional fluid compressing apparatus described above, however, the compressed fluid is often incompletely discharged, which retains some residual fluid at the discharge port  32  of the valve plate  30 . Such residual fluid re-expands during the fluid suctioning process in which the piston  20  is moved from the top dead end point T to the bottom dead end point B. The problem arises in the initial fluid suctioning process where the piston  20  is moved toward the bottom dead end point B. That is, due to the presence of re-expanding residual fluid, the pressure in the cylinder bore  11  is initially higher than the pressure in the suction chamber  41 , although the pressure in the cylinder bore  11  is lower than the pressure in the discharge chamber  42  of the cylinder head  40 . Accordingly, the suctioning does not occur at the beginning of the stroke of the piston  20  toward the bottom dead end point B. Then the suction valve  33  is opened to draw in the fresh fluid when the pressure in the cylinder bore  11  becomes lower than the pressure in the suction chamber  41 , which is obtained only when the piston  20  moves toward the bottom dead end point B for a sufficient period of time. In other words, the residual fluid from the fluid compression and discharge in the conventional fluid compressing apparatus causes a clearance volume in the cylinder bore  11  that makes a certain space in the cylinder bore  11  unavailable. Accordingly, the amount of drawn fluid decreases, and pumping efficiency deteriorates considerably. 
     Further, due to the complicated structure that is used for the suction valve  33  and the discharge valve  34  for opening/closing the fluid suction port  31  and discharge port  32 , the conventional apparatus is difficult to assemble and productivity thus deteriorates, and manufacturing costs increase considerably. 
     SUMMARY OF THE INVENTION 
     The present invention has been made to overcome the above-mentioned problems of the related art, and accordingly, it is an object of the present invention to provide a fluid compressing apparatus for increasing pumping efficiency by discharging compressed fluid completely out of the bore and thus minimizing clearance volume in the cylinder bore. 
     Another object is to provide a fluid compressing apparatus having a simple structure and being easy to assemble and thereby increasing productivity and reducing manufacturing costs, by using a piston to open and close a fluid suction port, thereby omitting a need to use a separate suction valve device, and providing a discharge valve device having a simple structure. 
     The above objects are accomplished by providing a fluid compressing apparatus according to the present invention, including a cylinder block having a cylinder bore of a predetermined diameter penetrating through the cylinder block in a lengthwise direction, a discharge chamber having a diameter larger than the diameter of the cylinder bore, and at least one fluid suction port penetrating in the cylinder block in a substantially perpendicular direction with respect to the cylinder bore, the cylinder block using a certain space thereof that is interconnected with the discharge chamber of the cylinder borer as a fluid discharge port; a piston movably disposed in the cylinder bore of the cylinder block to be linearly reciprocated; a discharge valve assembly having a valve plate disposed to be resiliently biased from the discharge chamber toward the fluid discharge port so as to selectively open or close the fluid discharge port of the cylinder block; and a cylinder head disposed at an end of the discharge chamber of the cylinder block, and having a fluid discharge channel interconnected with the discharge chamber. 
     According to the present invention, the fluid is drawn when the fluid suction port is selectively opened by the linear reciprocation of the piston within the cylinder bore of the cylinder block, and discharged when the fluid discharge port is opened by the valve plate that is separated from the fluid discharge port by the high pressure of the fluid in the cylinder bore caused by the reciprocating piston. Since suction valves having complicated structure are omitted, ease of assembly and improved productivity are achieved, and manufacturing costs are reduced. Also, since the high pressure fluid, compressed in the cylinder bore, is discharged through the fluid discharge port completely, a clearance volume in the cylinder bore can be avoided or minimized, and thus, the compression efficiency is enhanced. 
     In the fluid compressing apparatus according to the preferred embodiment of the present invention, a top dead end point of the piston is slightly beyond an extreme end of the cylinder bore, thereby discharging the fluid compressed in the cylinder bore completely when the piston contacts the valve plate. 
     The fluid suction port is positioned adjacent a bottom dead end point of the piston, i.e., adjacent to an extreme end point for the movement of the piston, so that the fluid suction port is instantly opened when the piston reaches the bottom dead end point and a fluid is drawn rapidly through the open fluid suction port. 
     The discharge valve assembly includes the valve plate disposed to be separable and floatable from the fluid discharge port of the cylinder block, and having a first boss formed approximately at a center of one side; a supporting plate disposed in the discharge chamber of the cylinder block at a predetermined distance from the valve plate, the supporting plate having a second boss formed at one side corresponding to the first boss, and a plurality of fluid passages formed around the second boss in a radial direction; and an resilient member disposed between the valve plate and the supporting plate, for resiliently biasing the valve plate toward the fluid discharge port. 
     The cylinder block has a circular or a rectangular outer structure. Two fluid suction ports can be provided to the cylinder block and these may be diametrically opposed to each other. Alternatively, more than two fluid suction ports can be provided to the cylinder block disposed at a predetermined space from each other. 
     The fluid suction port can be tapered, or formed into a double-layered structure consisting of a large diameter portion and a smaller diameter portion, or formed as a combination of the tapered and double-layered structure. 
     The area of the fluid suction port utilized for drawing the fluid is preferably widened by cutting away at least a certain portion of the cylinder block, for more efficient drawing of the fluid. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects and features of the present invention will become apparent from the following description of the preferred embodiments given in conjunction with the accompanying drawings, in which: 
     FIGS. 1 and 2 are sectional views schematically showing the structure and operation of a conventional fluid compressing apparatus; 
     FIG. 3 is an exploded perspective partially cutaway view of a fluid compressing apparatus according to a preferred embodiment of the present invention; 
     FIGS. 4 through 7 are sectional views showing the structure and operation of the fluid compressing apparatus according to a preferred embodiment of the present invention; 
     FIGS. 8A through 8G are cross-sectional and perspective views showing various embodiments of the cylinder block and fluid suction port of the fluid compressing apparatus according to the present invention; and 
     FIG. 9 is a perspective view showing another embodiment of the cylinder block and the fluid suction port of the fluid compressing apparatus according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The preferred embodiment of the present invention will now be described with reference to the drawings. 
     FIG. 3 is an exploded perspective view, shown in partial cutaway cross-section, of a fluid compressing apparatus according to the preferred embodiment of the present invention, and FIGS. 4 through 7 are sectional views for explaining the structure and operation of the fluid compressing apparatus of FIG.  3 . 
     As shown in FIGS. 3 through 7, the fluid compressing apparatus according to the preferred embodiment of the present invention includes a cylinder block  100 , a piston  200 , a discharge valve assembly  300  and a cylinder head  400 . 
     The cylinder block  100  includes a cylinder bore  110  of a predetermined diameter penetrated through the cylinder block  100  in a lengthwise direction, a discharge chamber  120  having a diameter larger than the diameter of the cylinder bore  110 , and at least one fluid suction port  130  penetrated through the cylinder block  100  in a direction perpendicular to longitudinal extension of the cylinder bore  110 . The space interconnecting with the discharge chamber  120  in the cylinder bore  110  is used as a compressed fluid discharge port  140 . 
     The cylinder block  100  can have a cylindrical outer structure as shown in FIGS. 8A through 8G, or a rectangular outer structure as shown in FIG.  9 . The shape of the cylinder block  100  is capable of taking any practical form. In other words, the shape of the outer structure of the cylinder block  100  is not limited to the certain shapes illustrated and described herein. 
     As best shown in FIG. 3, the discharge chamber  120  is of a double-layered structure in which separate sections having different diameters are formed adjacent each other. However, this structure is not strictly limited, and feasible modifications can be made. For example, some of the sections could have a uniform diameter, as shown, for example, in FIG.  8 D. 
     In this embodiment, although the fluid suction port  130  is formed in a direction perpendicular to the longitudinally extending cylinder bore  110 , this structure is not strictly limited to the illustrated embodiment only. Accordingly, if it is more advantageous in terms of desired flow rate and structure, the fluid suction port  130  can be formed at a certain angle (inclusive of acute and obtuse angles) with respect to the cylinder bore  110 . 
     The piston  200  is disposed to linearly reciprocate within the cylinder bore  110  of the cylinder block  100 . With the driving force transmitted from a separate driving source (not shown), the piston  200  linearly reciprocates within the cylinder bore  110  to thereby draw and compress the fluid. In order to reduce load to the piston  200 , the piston  200  is designed to be a hollow cylinder, and more preferably, to be made of an aluminum alloy. 
     The discharge valve assembly  300  is elastically biased from the discharge chamber  120  of the cylinder block  100  toward the fluid discharge port  140 , to selectively open or close the fluid discharge port  140  of the cylinder block  100 . The discharge valve assembly  300  has a valve plate  310  having a diameter slightly larger than the diameter of the fluid discharge port  140 . 
     The valve plate  310  is supported such that it is not rigidly attached to the bore  110 , but can float relative to the fluid discharge port  140 . The valve plate  310  has a first boss  311  formed approximately at the center of a rear surface, opposite to the surface facing the discharge port  140 . Further, the discharge valve assembly  300  includes a supporting plate  320  disposed at the rear end of the discharge chamber  120  at a predetermined space from the valve plate  310 , and a resilient member  330  disposed between the valve plate  310  and the supporting plate  320  to resiliently urge the valve plate  310  toward the fluid discharge port  140 . Accordingly, when the cylinder bore  110  is not subject to pressure, i.e., during the fluid suctioning process, the valve plate  310  is urged toward close contact with the fluid discharge port  140 , thereby closing off the fluid discharge port  140 . Then as the cylinder bore  110  is subject to a growing pressure, i.e., during the fluid compressing process, the valve plate  310  overcomes the resistance of the resilient member  330  and as a result of the high pressure of the fluid in the cylinder bore  110 , causes the valve plate  310  to separate from and open the fluid discharge port  140 , thereby letting the fluid out. 
     The supporting plate  320  has a second boss  321  formed approximately at the center thereof, corresponding to and oppositely facing the first boss  311 . Three or more fluid passages  322  preferably are formed around the second boss  321  at a predetermined distance from each other and may be disposed in a radial direction. The supporting plate  320  can be secured to the discharge chamber  120  of the cylinder block  100  by appropriate fastening methods, such as screwing or welding. 
     The resilient member  330 , may comprise a compression coil spring. When using the compression coil spring, the spring is supported at each end and disposed around the first and the second bosses  311  and  321  formed on the valve plate  310  and the supporting plate  320 , respectively. Instead of the compression coil spring, other types of resilient member can also be used, for example, a flat spring, or even a magnetic repelling mechanism. 
     The cylinder head  400  is disposed at the end of the discharge chamber  120  of the cylinder block  100 , and has a fluid discharge channel  410  that is preferably formed at the center and is interconnected with the discharge chamber  120 . There is no absolutely prescribed shape or structure of forming the cylinder head  400 . A connecting means, such as a screw, is employed in this embodiment to connect the cylinder head  400  to the chamber  120 . 
     As shown in each of FIGS. 3 through 7, a fluid suction manifold  500  provides a means for introducing new fluid to the compressing apparatus. 
     In the fluid compressing apparatus constructed as described above according to the present invention, the fluid suction port  130  is selectively opened by the piston  200  that linearly reciprocates within the cylinder bore  110 . Due to a vacuum that is developed in the cylinder bore  110 , the fluid is drawn in rapidly, and due to the high pressure of the fluid developed in the cylinder bore  110 , the valve plate  310  floats so as to separate from the fluid discharge port  140 , thereby opening the fluid discharge port  140  and enabling complete discharge of the fluid. 
     The characteristic and the structure that enables the unique effect of the present invention is that, as shown in FIG. 4, the top dead end point T of the piston  200  is disposed slightly beyond the extreme end of the cylinder bore  110 . Accordingly, the first unique effect of the present invention is that the compressed fluid within the cylinder bore  110  is completely discharged when the piston  200  contacts with and longitudinally displaces the valve plate  310 . Unlike the conventional compressor, the structure according to the present invention allows no residual fluid in the cylinder bore  110 , and as a result, any clearance volume is prevented or minimized. 
     The characteristic and the structure that enables the second unique effect of the present invention is that the fluid suction port  130  is formed slightly before the extreme rear end point of the cylinder bore  110 , i.e., before the bottom dead end point B reached by the piston  200 , and that the piston  200  serves to selectively open the fluid suction port  130  while reciprocating in the cylinder bore  110  omitting a need to use a separate suction valve assembly. When the piston  200  reaches the bottom dead end point B, the fluid suction port  130  is suddenly opened, and fresh fluid is rapidly drawn into the cylinder bore  110  since it is in a vacuum state. Since there is no need to employ a complicated suction valve assembly, the structure is simplified. Also, since the fluid is drawn rapidly, there arises a cooling effect of the cylinder block  100 . 
     Meanwhile, in the fluid compressing apparatus according to the present invention, since the fluid is drawn through the fluid suction port  130  when the fluid suction port  130  is suddenly opened by the movement of the piston  200 , the amount of the drawn fluid can sometimes be insufficient. Taking this into account, some embodiments of the present invention may include at least two fluid suction ports  130  and  130 ′ formed diametrically opposite each other in the cylinder block  100 , enabling drawing of the fluid in greater amounts (See FIGS.  8 A through  8 H). 
     According to another embodiment of the present invention, shown in FIG. 8A, the fluid suction ports  630  and  630 ′ are tapered to have a gradually decreasing diameter from outside to the inside of the cylinder block  600 . Alternatively, the fluid suction ports  730  and  730 ′ may be formed in double layers having large-diameter space  732  and a smaller-diameter space  734  as shown in FIG.  8 B. Also, one fluid suction port  830  can be formed in a double-layered structure having a large-diameter space  832  and a smaller-diameter space  834 , while the other fluid suction port  830 ′ is formed as a hole of a predetermined diameter  836 , as shown in FIG.  8 C. Also, both of the fluid suction ports  930  and  930 ′ may be formed as holes of predetermined diameters  932 , as shown in FIG.  8 D. Also, in another embodiment  890 , one fluid suction port  680  can be tapered to have a gradually decreasing diameter from outside to the inside of the cylinder block structure, while the other fluid suction port  880  is formed as a double-layered structure having a large-diameter space  882  and a smaller-diameter space  884 , as shown in FIG.  8 H. 
     According to still another embodiment of the present invention, a plurality of fluid suction ports  1030  are formed over the entire outer circumference of the cylinder block  1000  in order to ensure a greater area for drawing the fluid, as shown in FIG.  8 G. 
     Alternatively, as shown in FIG. 8E, the area  1130  for drawing the fluid is widened by cutting out a certain portion of the cylinder block  1100 . FIG. 8F shows still another embodiment, in which a cutaway portion  1228  having a predetermined width and a predetermined depth is formed along the outer circumference of the cylinder block  1200 , and a plurality of fluid suction ports  1230  are formed in the cutaway portion at a predetermined distance from each other. 
     FIG. 9 shows still another embodiment of the present invention. As shown in FIG. 9, the cylinder block  1300  according to this embodiment of the present invention has a rectangular outer structure, and fluid suction ports  1330  and  1330 ′ formed in one or two cutaway portion formed in the rectangular cylinder block  1300 . In this embodiment, the area for the fluid suction ports is increased, and accordingly, the drawing of fluid into the cylinder bore becomes more efficient. 
     The operation of the fluid compressing apparatus constructed as above described according to the present invention will be generally described with reference to FIGS. 4 through 7. Although only the operation of only one embodiment is shown and described, the operation is similar with respect to each of the above-described embodiments. 
     FIG. 4 shows the piston  200  in the cylinder bore  110  completely displaced to the bottom dead end point B. As shown in FIG. 4, when the piston  200  is displaced to the bottom dead end point B, the fluid suction port  130 , which was closed by the piston  200 , is opened, letting the fluid into the cylinder bore  110  therethrough. More specifically, the fluid discharge port  140  of the cylinder bore  110  is in the closed state when the piston  200  starts moving from the top dead end point T to the bottom dead end point B. With the fluid discharge port  140  of the cylinder bore  110  in the closed state, and with the fluid suction port  130  being closed by the piston  200 , a vacuum is produced in the cylinder bore  10  when the piston  200  is forced to move to the bottom dead end point B by the exterior driving source (not shown). The suction force becomes greater as the piston  200  moves closer to the bottom dead end point B. Then when the piston  200  finally reaches the bottom dead end point B, opening the fluid suction port  130 , the fluid is rapidly drawn through the fluid suction port  130  into the cylinder bore  110 . 
     FIG. 5 shows the piston  200  moving toward the top dead end point T after returning from the bottom dead end point B, and thus compressing the fluid that was drawn into cylinder bore  110 . As the piston  200  moves, the fluid suction port  130  is closed, and due to the resistance of the resilient member  330  disposed on the opposite side of the valve plate  310 , the valve plate  310  keeps close contact with the fluid discharge port  140  and thus closes off the fluid discharge port  140 . With the fluid suction port  130  and the fluid discharge port  140  being closed, the drawn fluid is gradually compressed as the piston  200  is forced to move to the top dead end point T. 
     FIG. 6 shows the piston  200  in the position where it is reaching the top dead end point T. The fluid that was previously drawn into the cylinder bore  110  is gradually compressed as the piston  200  moves closer to a certain point. Then as the piston  200  reaches the end point T, the imbalance between the pressure of the fluid and the resistance of the resilient member  330  resiliently supporting the valve plate  310  (i.e., pressure of fluid is greater than the resistance of the resilient member causes the valve plate  310  to separate and float from the fluid discharge port  140 , and accordingly, the high-pressure fluid is discharged completely from the cylinder bore  110  into the discharge chamber  120  through the open fluid discharge port  140 . The piston  200  comes into contact with the valve plate  310  at the instant that the last amount of fluid is just about to be discharged. The last amount of the higher-pressure fluid serves as a buffer against the collision of the piston  200  and the valve plate  310 , before it is finally discharged to the discharge chamber  120  when the piston  200  passes the extreme end of the cylinder bore  110  and reaches the top dead end point T. Since there is no residual fluid in the cylinder bore  110  after the piston  200  reaches the top dead end point T, ideally no clearance volume remains in the cylinder bore  110 . 
     FIG. 7 shows the piston  200  returning from the top dead end point T toward the bottom dead end point B after the compression of the fluid. As shown in FIG. 7, almost simultaneously with the piston  200  moving toward the bottom dead end point B, the valve plate  310  is pressed into close contact with the fluid discharge port  140  by the resilient member  330  to close the fluid discharge port  140 . Also, the fluid suction port  130  is closed by the piston  200 . As the piston  200  moves closer to the bottom dead end point B, the degree of vacuum in the cylinder bore  110  increases with increasing volume defined by the walls of cylinder bore  110  and the end wall of the piston  200 . Then, as the piston  200  reaches the bottom dead end point B, as shown in FIG. 4, the fluid suction port  130  is opened, and accordingly, fresh fluid is rapidly drawn into the cylinder bore  110  through the fluid suction port  130  by the suction force of the vacuum in the cylinder bore  110 . The compression and drawing of the fluid repeats sequentially so that the fluid is drawn in, compressed and discharged continuously. 
     Although the fluid compressing apparatus, which draws and compresses the fluid (gas in this embodiment) into high pressure and discharges the high-pressure fluid, is particularly used in this embodiment as a way of example, those skilled in the art would note that the present invention can also be applied to a fluid pumping apparatus, for example, to a pump. 
     As described above, according to the present invention, since there is no compressed high-pressure fluid remaining in the cylinder bore  110 , clearance volume in the cylinder bore is minimized. As a result, the compression efficiency increases, and thus it would considerably increase the cooling or freezing efficiency when applied into a compressor of a refrigerator or air conditioner. 
     Further, according to the present invention, the suction valves having complicated structure are omitted and the inventive discharge valve is formed having simple construction. Accordingly, the structure of the compressor becomes simplified, and the compressor also becomes easy to assemble, resulting in improved productivity and reduction in manufacturing cost. 
     Further, according to the present invention, the suction valve is omitted and the operation of the discharge valve is improved, and the noise, which is generated in conventional compressors due to beating of the valve, is prevented. As a result, operation of the compressor is quieter. 
     In conclusion, according to the present invention, a compressor of a pump of high compression efficiency and reliability and simple structure is provided with enhanced ease of assembly and improved productivity at an economic cost. 
     While the invention has been shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the sprit and scope of the invention as defined by the appended claims.