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Head discharging compressor systemHead discharging compressor system description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20080063551, Head discharging compressor system. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND [0001]Reciprocating air compressor systems are used to provide compressed air for the operation of various types of mechanical and pneumatic devices. Such systems are manufactured in a broad range of sizes and capacities that allow for air deliveries that vary from less than 1 Standard Cubic Foot per Minute ("SCFM") to more than 100 SCFM. A piston is commonly employed to reciprocate with repeated intake and compression strokes within a compression cylinder. In most reciprocating compressor systems, an arrangement of valves allows air to be drawn from the environment surrounding the compressor system through at least one inlet valve into a compression cylinder where the air is compressed. The compressed air is then channeled through at least one outlet valve and a discharge tube into an air reservoir where air is stored. The air pressure within the air reservoir is normally maintained within a predetermined pressure range by the operation of the compressor. [0002]An air reservoir check valve allows compressed air at a pressure greater than that of the reservoir to flow from the compressor through the discharge tube and into the reservoir. The air reservoir check valve also prevents air from flowing from the reservoir back into the discharge tube when the compressor is off. However, when the compressor turns off, a residual pressure, called a back pressure, remains within the discharge tube and on the piston within the compression cylinder when the compressor starts up again. [0003]It is usually desirable to relieve back pressure on the piston when the piston is not reciprocating within the compression cylinder since the piston must overcome this back pressure as it starts to compress air. Relieving the back pressure significantly improves the performance of the compressor system and extends the operational life of the compressor pump. To relieve back pressure, compressor systems often employ a bleed orifice downstream from the compression cylinder sometimes included as part of an air reservoir check valve. The bleed orifice continuously allows compressed air to flow to the surrounding atmosphere from the discharge tube and connected compression cylinder. When the piston is not reciprocating within the compression cylinder, the bleed orifice unloads backpressure from the piston at a preselected rate of unloading determined by the diameter of the bleed orifice. [0004]When the piston reciprocates within the compression cylinder, the larger clearance of the open outlet valve from the compression chamber and the larger diameter of the discharge tube, compared to the significantly smaller diameter of the bleed orifice, allow an amount of air to be compressed that is sufficient to increase pressurization of the air reservoir. However, as a result of the downstream location of the bleed orifice from the compression cylinder, compressed air is discharged continuously from the bleed orifice while the piston reciprocates within the compression cylinder. Thus, some air pressure within the discharge tube is wasted continuously through the bleed orifice as the piston reciprocates. This causes an inherent inefficiency in the compressor system that is directly related to the amount of air pressure lost through the bleed orifice. [0005]Compressor systems can also become less efficient if the compression cylinder is not substantially sealed from the discharge tube during intake strokes of the piston. During each compression stroke, air that has been compressed and that has moved downstream through the discharge tube tends to acquire additional heat energy. If the compressed air subsequently escapes from the discharge tube back into the compression cylinder, the heated, previously compressed air may be less dense than cooler air entering the compression cylinder through the inlet valve. [0006]The escape of air from the discharge tube back to the compression cylinder can be caused by an incompletely sealed outlet valve or another opening between the compression cylinder and discharge tube. The resulting leakage of air between the compression cylinder and discharge tube during intake strokes of the piston can produce a condition known as reversion. In this condition, since the heated, previously compressed air present within the compression cylinder can have a density less than cooler air entering through the inlet valve, thee amount of air taken from the atmosphere during each piston stroke is reduced and can lead to lower compressed air production by the compressor. [0007]If the compression chamber outlet valve is not substantially leak free or if a bleed orifice is located downstream of the outlet valve at a location such as the discharge tube, the discharge tube will be unable to sustain the pressure of compressed air within the air reservoir when the piston is not reciprocating. As a result, an additional check valve is normally required to maintain air pressure within the compression cylinder. The inclusion of such additional components can significantly increase the overall unit construction cost of the compressor system. [0008]Such typical limitations of prior art systems can be best understood with reference to the example prior art reciprocating air compressor system 20 depicted in FIGS. 1-3. Referring first to the partial cross sectional view of the compressor system 20 depicted in FIG. 1, the compressor system 20 includes an air compressor pump 22 having a compression cylinder 24 in which a piston 26 is positioned to reciprocate in intake strokes (downward in FIG. 1) and compression strokes (upward in FIG. 1). The piston 26 is powered with an electric motor 28 that actuates the piston 26 using a belt 30, flywheel pulley 32, and crankshaft 34, connected to the piston 26 via a piston rod and pin assembly 35. The belt is moved by engaging a pulley (not shown) attached to the rotating shaft (not shown) of the meter 28. The moving belt rotates the flywheel pulley 32 that it engages, rotating the crankshaft 34 that is attached to the pulley 32. The rotating crankshaft 34 causes the piston rod and pin assembly 35, and thus the piston 26, to reciprocate within the compression chamber 24. The compressor pump 22 and electric motor 28 are mounted on an air reservoir 36. [0009]As the piston 26 reciprocates within the compression cylinder 24, each intake stroke of the piston 26, during which the piston 26 moves in a downward direction in the compression chamber 24, causes air to be drawn from the environment surrounding the compressor system 20 through an air filter 40 into a cylinder inlet chamber 42. Referring briefly to FIG. 2, which depicts a magnified cross sectional view of the compressor pump 22, a first reed valve serves as an inlet valve 44. The inlet valve 44 allows a unidirectional flow of air from the cylinder inlet chamber 42 to the compression cylinder 24 throughout the duration of the intake stroke since the pressure created by the downward direction of the stroke pulling the reed of the valve 44 into the compression chamber 24. A second reed valve serves as an outlet valve 46, which is also unidirectional and prevents air from being drawn from a cylinder outlet chamber 48 and a discharge tube 50 connected to it throughout the duration of the intake stroke since the pressure created by the downward intake stroke tends to pull the reed of the outlet valve 40 toward the compression chamber 24. However, the outlet valve 46 does not completely seal the cylinder outlet chamber 48 from the compression cylinder 24 during the duration of the intake stroke. As a result, any backpressure present within the cylinder outlet chamber 48 which would be at a higher pressure than the pressure within the compression cylinder 24 during the downward stroke, can result in some pressurized air entering the compression chamber through the outlet valve 46 during the intake stroke. [0010]During each compression stroke, the piston (not shown in FIG. 2) moves in an upward direction in the compression cylinder 24 and thus forces air through the outlet valve 46 and into the cylinder outlet chamber 48. The inlet valve 44, which is then forced against the valve plate at the top of the compression chamber 24, prevents air from flowing back through the inlet valve 44 and into the cylinder inlet chamber 42. Any air that has returned or reverted to the cylinder outlet chamber 48 back from the discharge tube 50 and the outlet chamber 48 and through outlet valve 46 during the intake stroke ultimately leads to a reduction in the overall amount of air that has been compressed and leads to an increase in intake air temperature leading to lower compressed air production and lower efficiency of the compressor system 20. [0011]Referring again to FIG. 1, as the piston 26 reciprocates within the compression cylinder 24, air that has been compressed and forced through the outlet valve 46 flows through the cylinder outlet chamber 48 to a discharge tube 50 which channels air to a reservoir check valve 52. FIG. 3 depicts a magnified partial cross sectional view of the reservoir check valve 52 connecting the discharge tube 50 to the air reservoir 36. [0012]As best understood by comparing FIG. 1 to FIG. 3, the reservoir check valve 52 includes a valve body 53 and a bleed orifice 54 that is open to the interior cross section of the discharge tube 50 and to the atmosphere surrounding the air compressor system 20. The bleed orifice 54 allows air pressure to constantly escape from the discharge tube 50 and thereby slowly removes backpressure from the cylinder outlet chamber 48 when the piston 26 is not reciprocating in the compression cylinder 24. [0013]The reservoir check valve 52 also includes a plug 56 having a tapered section 58. The plug 56 is shaped with flutes 57 (shown in FIG. 3) to allow an air passage 59 to extend from within the valve body 53 to the air reservoir 36. An elastomeric o-ring 60 is positioned to reciprocate on the tapered section 58 of the plug 56. The o-ring 60 is biased away from an o-ring stop 62 to a closed valve position (shown in FIG. 3) where the o-ring 60 seals between the valve body 53 and the plug 56 to prevent air from passing through the air passage 59 into the air reservoir 36. [0014]When the piston 26 reciprocates in the compression cylinder 24, air forced through the outlet valve 46 by compression strokes of the piston 26 pressurizes the cylinder outlet chamber 48 and discharge tube 50. Some air from within the cylinder outlet chamber 48 escapes back through the unsealed outlet valve 46 through reversion during each subsequent intake stroke of the piston 26. As long as air pressure within the discharge tube 50 is greater than in the environment surrounding the air compressor system 20, air flows continuously through the bleed orifice 54 to slowly but constantly remove air pressure within the discharge tube 50. If the air pressure within the discharge tube 50 is initially sufficient to exert a cracking force against the o-ring 60 of the reservoir check valve 52 and remains sufficiently greater than the air pressure contained within the air reservoir 36 to overcome the biasing force of the o-ring 60, the o-ring 60 is forced to stretch outward and down the tapered section 58 toward the o-ring stop 62 to an open position (not shown in FIG. 3). This open position of the o-ring 60 allows air to flow from the discharge tube 50 into the air reservoir 36. [0015]Although some compressed air from the valve outlet chamber 48 is lost by reversion during intake strokes of the piston 26 and although some pressurized air is constantly lost during operation of the compressor 22 through the bleed orifice 54, the rate at which air is lost is less than the rate at which air can be compressed by the reciprocating piston 26. The cross sectional areas of the air passage 59 (see FIG. 3) and open position clearance between the o-ring 60 and valve body 53 are also sufficiently large to allow flowing compressed air to enter the air reservoir 36 faster than air can be removed by reversion or through the bleed orifice 54. The bleed orifice 54 serves a useful function of removing backpressure from the discharge tube 50 and cylinder outlet chamber 48 when the piston 26 is not reciprocating, reducing the initial load against the piston 26 and therefore reducing the initial burden on the motor 28 at the start of system operation. However, as long as the compressor pump 22 continues to compress air, reversion constantly reduces the efficiency of the compressor pump 22 and air loss through the bleed orifice 54 occurs at a continuous rate. SUMMARY [0016]A cylinder arrangement for a reciprocating air compressor system includes a compressor pump having a compression cylinder. A piston is positioned to reciprocate with intake and compression strokes within the compression cylinder. An inlet valve has open and closed positions, an inlet valve clearance being present in the inlet valve when the inlet valve is in the open position. The inlet valve moves to the open position and allows air to enter the compression cylinder through the inlet valve clearance during intake strokes of the piston. The inlet valve moves to the closed position and prevents air from exiting the compression cylinder through the inlet valve clearance during compression strokes of the piston. [0017]An orifice has a minimum cross sectional area smaller than the effective area of the inlet valve clearance. The orifice is positioned to allow air to enter the compression cylinder during intake strokes of the piston and to allow air to exit the compression cylinder during compression strokes of the piston. The amount of air passing through the orifice is significantly less than the amount of air passing through the inlet valve clearance during each intake stroke. When the piston is not reciprocating within the compression cylinder, remaining backpressure within the compression cylinder is relieved through the orifice. [0018]A second embodiment also includes a discharge tube and allows compressed air to flow from the compressor pump to an air reservoir. An outlet valve having open and closed positions moves to the open position and allows air to exit the compression cylinder and enter the discharge tube during compression strokes of the piston. The outlet valve moves to the closed position and prevents air from entering the compression cylinder through the outlet valve during intake strokes of the piston. The outlet valve also moves to the closed position to prevent air from the discharge tube and air reservoir from entering the compression cylinder through the outlet valve when the piston is not reciprocating in the compression cylinder. The outlet valve is constructed so that when in the closed position it is substantially leak free and is generally capable of sealing the backpressure of the discharge tube to preserve the pressure of compressed air in the air reservoir. [0019]The placement of the orifice to allow air to enter the compression cylinder through the orifice during intake strokes of the piston and to only allow air to exit the compression cylinder through the orifice during compression strokes of the piston allows for an approximately 50% reduction in the amount of compressed air that is wasted through the orifice while the piston reciprocates within the compression cylinder. This is done without reducing the ability of the orifice to remove backpressure from the piston when the piston is not reciprocating. [0020]This placement of the orifice allows for the usage of a substantially leak free valve, such as an elastomeric o-ring valve, as an outlet valve. If the outlet valve is substantially leak free, it is possible to use outlet valve to seal and allow for pressure of the air reservoir to be maintained within the discharge tube, eliminating the need for an additional check valve to prevent the escape of air pressure from the air reservoir to the surrounding atmosphere. [0021]The use of a substantially leak free valve prevents the leaking or reversion of compressed air back through the outlet valve when the outlet valve is closed during intake strokes of the piston. This allows for an increase in the amount of air that can be drawn into the pump from the surrounding atmosphere and leads to greater efficiency of the compressor pump. [0022]In some embodiments, the use of a substantially leak free valve, such as an elastomeric o-ring valve, as an outlet valve also allows for improved cooling of the compressor pump since a hollow valve shaft can be used to enhance the transfer of heat to cooler air flowing throughout the cooling fins and across the cylinder head of the pump. Continue reading about Head discharging compressor system... Full patent description for Head discharging compressor system Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Head discharging compressor system patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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