Abstract:
A pump assembly for a penile implant is provided having a mechanism which prevents spontaneous inflation of the cylinders implanted within the user. The preventative mechanism uses overpressure generated by the reservoir during unintentional compression to effectively seal the pump assembly from unintended fluid flow. The prevention mechanism itself creates all necessary forces to prevent the undesired fluid flow to the cylinders. This is accomplished by incorporating appropriate mechanisms within the pump itself.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is related to patent applications entitled “SLIDE VALVE AND SUCTION BASED SPONTANEOUS INFLATION INHIBITOR IN A PUMP FOR AN INFLATABLE PROSTHESIS” and “SWITCH BASED SPONTANEOUS INFLATION INHIBITOR IN A PUMP FOR AN INFLATABLE PROSTHESIS,” which were filed concurrently herewith.  
       BACKGROUND OF THE INVENTION  
       [0002]     This invention generally relates to a pump for inflating a prostheses and more particularly to a pump and valve assembly including a diaphragm which inhibits spontaneous inflation of the prosthesis.  
         [0003]     One common treatment for male erectile dysfunction is the implantation of a penile prosthesis. Such a prosthesis typically includes a pair of inflatable cylinders which are fluidly connected to a fluid reservoir via a pump and valve assembly. The two cylinders are normally implanted into the corpus cavernosae of the user and the reservoir is typically implanted in the user&#39;s abdomen. The pump assembly is implanted in the scrotum. During use, the user actuates the pump and fluid (typically liquid) is transferred from the reservoir through the pump and into the cylinders. This results in the inflation of the cylinders and thereby produces the desired penis rigidity for a normal erection. Then, when the user desires to deflate the cylinders, a valve assembly within the pump is actuated in a manner such that the fluid in the cylinders is released back into the reservoir. This deflation then returns the penis to a flaccid state.  
         [0004]     With inflatable penile prostheses of current designs, spontaneous inflation of the cylinders is known to occasionally occur due to inadvertent compression of the reservoir. Specifically, this inadvertent compression results in the undesired introduction of fluid into the cylinders. While this does not create a medical or physical problem, such inadvertent inflation can be uncomfortable and embarrassing for the user. This undesirable condition is further described below with reference to a particular prosthetic design.  
         [0005]     With reference to  FIG. 1 , a known pump and valve assembly  8  for use in a penile prosthesis includes a fluid input  10  that is coupled at one end to a reservoir (not shown) and to a housing  12  at its opposite end. Also connected to the housing  12  is a fluid output  14  which, in turn, is connected at its other end to a pair of cylinders (not shown). Linking the fluid input  10  and the fluid output  14  to each other is a common passageway  33 , which itself contains a valve assembly that is described in greater detail below. Common passageway  33  is also in fluid communication with a pump bulb  18  that is used to move fluid from the reservoir (not shown) to the cylinders (not shown) in order to inflate the cylinders. The valve assembly located within common passageway  33  includes a reservoir poppet  20  which is biased against a valve seat  24  by a spring  28  and a cylinder poppet  22  which is biased against a valve seat  26  by a spring  30 . The springs  28  and  30  are sized so as to keep the reservoir poppet  20  and the cylinder poppet  22  biased against each respective valve seat  24  and  26  under the loads that are encountered when the reservoir is pressurized to typical abdominal pressures.  
         [0006]     When the user wishes to inflate the cylinders, pump bulb  18  is squeezed so as to force fluid from the pump bulb  18  into the common passageway  33 . The resulting fluid flow creates a fluid pressure on reservoir poppet  20  which compliments the force of the spring  28  to hold the reservoir poppet  20  against valve seal  24 . The fluid flow also causes compression of the spring  30 , and thereby opening cylinder poppet  22 . As a result, the fluid travels out through fluid output  14  and into the respective cylinders.  
         [0007]     When the user releases the pump bulb  18  a vacuum is created, thus pulling the poppet  22  back against valve seat  26  (aided by spring  30 ) and simultaneously pulling the reservoir poppet  20  away from its valve seat  24 , against the spring  28 . As a result, fluid from the reservoir is thus allowed to flow through the fluid input  10  to the common passageway  33 , passing around the reservoir poppet  20 . Fluid then will freely flow into the vacuous pump bulb  18 . Once the pump bulb  18  has been filled, the negative pressure is eliminated and the reservoir poppet  20  returns to its normal position. This pumping action of the pump bulb  18  and valve assembly is repeated until the cylinders are fully inflated as desired.  
         [0008]     To deflate the cylinders, the user grips the housing  12  and compresses it along the axis of reservoir poppet  20  and cylinder poppet  22  in a manner such that the wall  13  of the housing  12  contacts the protruding end  21  of the reservoir poppet  20  and forces the reservoir poppet  20  away from valve seat  24 . This movement, in turn, causes the reservoir poppet  20  to contact cylinder poppet  22  and force cylinder poppet  22  away from valve seat  26 . As a result, both poppets  20  and  22  are moved away from their valve seats  21  and  26  and fluid moves out of the cylinders, through the fluid output  14 , through common passageway  33 , through the fluid input  10  and back into the reservoir.  
         [0009]     Although the springs  28  and  30  are sized to provide sufficient tension to keep poppets  20  and  22  firmly abutted against valve seats  24  and  26  under normal reservoir pressures, it is possible for fluid pressure to exceed the force provided by the springs during heightened physical activity or movement by the user. Specifically, this activity or movement can apply excess pressure to the reservoir. Such excessive pressure on the reservoir may overcome the resistance of the spring-biased poppets  20  and  22  and thereby cause a spontaneous inflation of the cylinders. Encapsulation or calcification of the reservoir can sometimes occur in a patient. This encapsulation could lead to a more snugly enclosed reservoir, thus increasing the possibility of providing excess pressure on the reservoir and the likelihood of spontaneous inflation.  
         [0010]     As such, there exists a need to provide a prosthetic penile implant having a spontaneous inflation prevention mechanism that is reliable and easy to operate.  
       BRIEF SUMMARY OF THE INVENTION  
       [0011]     The present invention includes a penile pump having a dual poppet arrangement wherein the poppets act as check valves or flow valves. Each poppet is spring-biased against a valve seat, and under normal circumstances, only allows positive fluid flow when a pump bulb is engaged. To prevent spontaneous inflation when an overpressurization occurs in the reservoir, the same reservoir pressure is utilized to seal the fluid output against itself or to seal one or both of the poppets against the valve seat. Thus, the fluid is prevented from reaching the cylinders and creating a spontaneous inflation. When the movement or activity generating the overpressure in the reservoir is released, the system will return to an equilibrium and allow normal operation. Even if overpressurization of the reservoir is occurring, the pressure generated by compressing the pump bulb will far exceed the level of overpressure. Thus, the poppets will open in the normal way, allowing fluid to flow to the cylinders.  
         [0012]     The use of the overpressure in the reservoir itself to prevent fluid flow to the cylinders can be accomplished in a variety of formats. Each of these formats however, generally utilize a structure in fluid communication with the reservoir which is capable of restricting flow caused by reservoir overpressurization.  
         [0013]     In a first embodiment, a bypass passageway is provided from the fluid input which terminates in an expansion chamber located directly behind the cylinder poppet. A portion of the housing forms a wall between this chamber and the cylinder poppet. This wall is larger in surface area than the surface area of the cylinder poppet exposed to the overpressure. Since the surface area of the wall is larger than the area of the poppet that contacts the valve seat, the same amount of pressure generated by the reservoir will cause a larger force to be applied by the chamber wall against the poppet than is applied against the poppet through the common passageway. Thus, the cylinder poppet is effectively sealed when an overpressurization occurs in the reservoir.  
         [0014]     In another embodiment, the bypass passageway is similarly coupled to the fluid input, bypassing the poppets and terminating in an expansion chamber. The cylinder poppet passageway output leads into a termination chamber connected to the expansion chamber. The expansion chamber is larger than the cylinder poppet output. Located within the expansion chamber is a flexible diaphragm dividing the chamber into two portions. As overpressurization occurs in the reservoir, this pressure is directed through the bypass passageway and is applied to the diaphragm. This pressure causes the diaphragm to flex against the output of the poppet chamber, effectively sealing it. In this sealing position, the diaphragm prevents fluid from reaching the cylinders.  
         [0015]     In yet another embodiment, a fluid bypass passageway is provided which connects the fluid input and a chamber which surrounds a portion of compressible tubing. The compressible tubing forms part of the output that leads from the cylinder poppet to the cylinders. As overpressurization occurs in the reservoir, this force is directed along the bypass passageway causing the flexible tubing to compress, thus effectively sealing it off. Once again this prevents fluid flow to the cylinders because the flexible tubing is part of the output.  
         [0016]     In a further embodiment, a fluid bypass passageway is provided between the reservoir and a fluid return passageway. The fluid return passageway couples an expansion chamber to an intermediate chamber between the reservoir poppet and the cylinder poppet. A bypass check valve is included in the bypass fluid passageway and allows pressurized fluid to flow from the input chamber into the return passageway. A return check valve is provided within the return fluid passageway between the intermediate chamber and the point where the bypass fluid passageway intersects the return fluid passageway.  
         [0017]     Thus, in an overpressure situation, pressurized fluid is allow to flow from the input chamber through the bypass fluid passageway and into the expansion chamber. The expansion chamber includes a flexible abutting wall which is caused to engage the cylinder poppet and to firmly seat it. In this situation, spontaneous inflation is avoided.  
         [0018]     While spontaneous inflation is prevented, pressurized fluid is able to enter the intermediate chamber. When the pressure of the fluid in the reservoir and the input chamber is reduced, this pressurized fluid remains in the intermediate chamber. If the expansion chamber were just allowed to relax when fluid pressure in the reservoir is reduced, it may be possible for the pressurized fluid in the intermediate chamber to open the cylinder poppet and partially inflate the cylinders. Thus, by providing this configuration of a bypass fluid passageway and a return passageway with the appropriate check valves, the pressured fluid entering the expansion chamber will be caused to remain there until the fluid pressure in the intermediate chamber is reduced. When the pump bulb is actuated, sufficient pressure is generated to overcome the opposing force generated in the expansion chamber and the cylinder poppet is unseated.  
         [0019]     In still another embodiment, a bypass fluid passageway and a return fluid passageway are provided wherein each includes a check valve as previously described. However, in this embodiment, both the bypass fluid passageway and the return fluid passageway are fluidly coupled to the input chamber. In addition, the return fluid passageway is coupled to the intermediate chamber. Located within the return fluid passageway between the intermediate chamber and the input chamber is a fluid resistor.  
         [0020]     When an overpressurization situation occurs, pressurized fluid will enter both the expansion chamber and the intermediate chamber. As previously described, the expansion chamber will seat the cylinder poppet firmly against the opening. As fluid pressure is reduced in the reservoir and input chamber, the fluid resistor allows pressurized fluid from the intermediate chamber to bleed back to the input chamber. Thus, eventually, the fluid pressure within the immediate chamber will be lower than the fluid pressure within the expansion chamber. Once this occurs, the return check valve will open and the pressurized fluid within the expansion chamber can return to the input chamber. Due to the configuration of the return check valve and the fluid resistor, pressure levels within the expansion chamber will always be higher than pressure levels within the intermediate chamber and, as a result, the cylinder poppet will always be firmly seated.  
         [0021]     In still yet another embodiment, a bypass fluid passageway and a return fluid passageway are provided wherein each is fluidly coupled to the input chamber. A check valve is placed within the bypass fluid passageway which only allows fluid to flow from the input chamber to the expansion chamber. Located within the return channel fluid passageway are a pair of fluid resistors placed on either side of a passageway into the intermediate chamber. When an over-pressurization situation occurs, pressurized fluid opens the bypass check valve and allows fluid flow through the bypass fluid passageway to the expansion chamber. This pressurized fluid then firmly seats the cylinder poppet. Pressurized fluid will also enter the intermediate chamber. When pressure is reduced in the reservoir and the input chamber the pressurized fluid trapped within the intermediate chamber is slowly able to bleed through a single fluid resistor into the input chamber. As fluid pressure is reduced in the intermediate chamber and the portion of the return fluid passageway located between the fluid resistors, the pressurized fluid within the expansion chamber is slowly able to bleed through the second fluid resistor and eventually into the input chamber.  
         [0022]     In still another embodiment a bypass fluid passageway is provided that couples the input chamber to an expansion chamber. The intermediate chamber is also fluidly coupled to the bypass fluid passageway. A first fluid resistor having a relatively low fluid resistance is placed between the intermediate chamber and the bypass fluid passageway. A second fluid resistor having a higher impedance is placed between the expansion chamber and the intermediate chamber. A bypass channel is constructed around the second fluid resistor and includes a bypass check valve allowing fluid to flow from the bypass fluid passageway around the second fluid resistor and into the expansion chamber. When an over-pressurization situation occurs, pressurized fluid will be trapped within the expansion chamber and the intermediate chamber. When pressure is reduced, pressurized fluid is able to flow from the intermediate chamber through the low impedance fluid resistor through the bypass fluid passageway and into the input chamber. As pressure levels drop within the bypass fluid passageway pressurized fluid will eventually be able to flow from the expansion chamber through the high impedance fluid resistor and into the input chamber. This configuration also ensures that fluid pressure levels within the expansion chamber will always be higher than those within the intermediate chamber (except during actuation of the pump bulb). Thus, preventing spontaneous inflation.  
         [0023]     In another embodiment, an input chamber is provided that is connected to the fluid input, prior to the point the fluid input engages the first poppet. At the output of the pump, a passageway leading from the cylinder poppet to the cylinders is caused to narrow in a throat region, which is located proximate the input chamber. When an overpressurization of the reservoir occurs this input chamber is caused to expand, thus forcing its outer walls to move outward. Outward movement of the outer walls effectively seals the throat portion, thus preventing fluid flow from the reservoir from reaching the cylinders.  
         [0024]     In still yet another embodiment a separate problem is addressed. Namely inadvertent compression of the valve walls may lead to an unseating of the reservoir and/or cylinder poppet and possibly lead to spontaneous inflation. To prevent this it may be desirable to make the housing substantially more rigid. This can be accomplished by encasing the reservoir and cylinder poppets within a solid cylindrical membrane.  
         [0025]     In most of the above outlined embodiments, the force generated by an overpressurization of the reservoir is used to prevent fluid flow into the cylinders. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0026]      FIG. 1  is a side-sectional view of a penile pump according to the teachings of the prior art.  
         [0027]      FIG. 2  is a side-sectional view of a penile pump in a state of equilibrium, having a termination chamber which can force the cylinder poppet against a valve seat during an overpressurization situation.  
         [0028]      FIG. 3  is a side-sectional view of the penile pump shown in  FIG. 2  during an overpressurization situation.  
         [0029]      FIG. 4  is a side-sectional view of a penile pump having a diaphragm member between a bypass passageway and the cylinder poppet output.  
         [0030]      FIG. 5  is a side-sectional view of a penile pump having a diaphragm between the bypass passageway and the cylinder poppet output.  
         [0031]      FIG. 6  is a side-sectional view of a penile pump having a bypass passageway which compresses a collapsible portion of the fluid output.  
         [0032]      FIG. 7  is a side-sectional view of a penile pump having a bypass fluid passageway and a return fluid passageway with a check valve located in each.  
         [0033]      FIG. 8  is a side-sectional view of a penile pump having a bypass fluid passageway and a return fluid passageway with a check valve located in each and a fluid resistor located within the return fluid passageway.  
         [0034]      FIG. 9  is a side sectional view of a penile pump having a bypass fluid passageway and a return fluid passageway with a check valve located in the bypass fluid passageway and a pair of fluid resistors located within the return fluid passageway.  
         [0035]      FIG. 10  is a side sectional view of a penile pump having a bypass fluid passageway with a pair of fluid resistors and a bypass channel with a check valve.  
         [0036]      FIG. 11  is a side-sectional view of a penile pump having a fluid output that has a reduced throat portion that is sealable during an overpressurization situation.  
         [0037]      FIG. 12  is a side sectional view of a penile pump having a rigidifying cylindrical element located within the housing. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0038]     Referring to  FIG. 1 , a pump assembly is shown and generally referred to as  8 . Pump assembly  8 , as illustrated in  FIG. 1 , is essentially that of the prior art, but an understanding of the working elements of pump assembly  8 , as illustrated in  FIG. 1 , is beneficial to understanding the operation of each embodiment of the present invention. Generally, the pump assembly  8  will be implanted into the user&#39;s scrotum. A separate fluid-filled reservoir (not shown) is implanted in some other portion of the user&#39;s body, usually in the abdomen. Fluidly connecting the reservoir to the pump assembly  8  is fluid input  10  which will usually be a flexible silicone tube. A pair of inflatable cylinders (not shown) are usually implanted in the user&#39;s corpus cavernosae and are fluidly connected to pump assembly  8  via fluid output  14 , which is also usually a flexible silicone tube.  
         [0039]     In general, when pump assembly  8  is actuated, fluid is drawn from the reservoir through the pump assembly  8  and pumped into the cylinders. During the inflation process and until released by the user, the pump assembly  8  maintains the fluid pressure in the cylinders, thus keeping them in their inflated state. When deflation is desired, the user manipulates assembly  8 , permitting fluid to transfer out of the inflatable cylinders and into the reservoir, thereby deflating the cylinders and returning them to a flaccid state.  
         [0040]     Pump assembly  8  generally includes a housing  12  usually formed of silicone. Attached to housing  12  is a pump bulb  18 , which includes a relatively large pump chamber  36 . Fluid input  10  is coupled to the housing  12  and empties into an input chamber  16 . As such, fluid input  10  couples input chamber  16  to the reservoir. A common passageway  33  is fluidly coupled between input chamber  16  at one end of the housing  12 , and fluid output  14  at an opposite end of the housing  12 . Similarly, the pump chamber  36  is fluidly coupled to the common passageway  33  via pump passageway  34 .  
         [0041]     Disposed within common passageway  33  is a reservoir poppet  20  which functions as a check valve. Reservoir poppet  20  is an elongated member having a contoured portion which abuts reservoir poppet valve seat  24  forming a fluid tight seal. A reservoir poppet spring  28  engages reservoir poppet  20  and biases reservoir poppet  20  against the reservoir poppet valve seat  24 . Also disposed within common passageway  33  and in line with reservoir poppet  20  is cylinder poppet  22 . Cylinder poppet  22  forms a second check valve within common passageway  33 . Cylinder poppet  22  is biased by cylinder poppet spring  30  against cylinder poppet valve seat  26  in a normal state, thereby forming another fluid tight seal within common passageway  33 . Reservoir poppet  20  is substantially longer than cylinder poppet  22 . A front end of reservoir poppet  20  extends into input chamber  16 , in close proximity to an outer wall of housing  12 . Furthermore, the front end of cylinder poppet  22  is in close proximity to the rear end of reservoir poppet  20 . As such, the user can manipulate both poppets  20  and  22  by compressing the wall of housing  12 . Compression of the housing  12  will cause the reservoir poppet  20  to compress reservoir poppet spring  28  thus displacing the reservoir poppet  20  from reservoir poppet valve seat  24 . This motion will also cause cylinder poppet  22  to be displaced from cylinder poppet valve seat  26  while compressing cylinder poppet spring  30 . When both reservoir poppet  20  and cylinder poppet  22  are displaced from their respective valve seats, fluid is allowed to freely flow between input chamber  16  and fluid output  14 , and hence fluid is allowed to freely flow between the reservoir and the cylinders.  
         [0042]     During a majority of the time, pump assembly  8  will be in the configuration shown in  FIG. 1 . That is, both reservoir poppet  20  and cylinder poppet  22  are abutting their respective valve seats  24  and  26 , forming a fluid tight seal. When inflation is desired, pump bulb  18  is manually compressed by the user. This forces the fluid in pump chamber  36  out through pump passageway  34  and into common passageway  33 , under relatively high pressure. Because of the location of pump passageway  34  with respect to the reservoir poppet  20 , this increased pressure causes reservoir poppet  20  to further abut reservoir poppet valve seat  24 . This increased pressure is more than sufficient to remove cylinder poppet  22  from its abutment with cylinder poppet valve seat  26 , by compressing cylinder poppet spring  30 . As such, the pressurized fluid is allowed to pass through a portion of the common passageway  33  and into fluid output  14 , where it eventually reaches an inflatable cylinder. When released, the pump bulb  18  expands back to its original configuration, creating negative pressure within pump chamber  36  and common passageway  33 . This negative pressure draws cylinder poppet  22  towards valve seat  26  and simultaneously pulls reservoir poppet  20  away from valve seat  24 . As such, fluid is drawn from the reservoir, and into pump chamber  36  until the negative pressure is eliminated. Then, reservoir poppet spring  28  causes the reservoir poppet  20  to reseat itself against valve seat  24 .  
         [0043]     Repeated compression of pump bulb  18  eventually inflates the cylinders to a sufficient degree of rigidity for the user. Once inflated, the fluid remaining in fluid output  14  is under a relatively high degree of pressure. This high pressure fluid aids cylinder poppet spring  30  in forcing cylinder poppet  22  against cylinder poppet valve seat  26  again forming a fluid tight seal and preventing fluid from within the cylinders from passing back through the pump assembly  8  (preventing deflation of the cylinders).  
         [0044]     When the user desires deflation of the cylinders, the wall of housing  13  is manually compressed. This compression forces reservoir poppet  20  away from reservoir poppet valve seat  24  and simultaneously causes cylinder poppet  22  to be removed from cylinder poppet valve seat  26 . The pressurized fluid within the cylinders and fluid output  14  naturally returns to the reservoir via common passageway  33 . Furthermore, the cylinders can be manually compressed forcing out any remaining fluid. Once the cylinders are satisfactorily emptied, the user releases the grip on housing  12 , thus allowing cylinder poppet  22  and reservoir poppet  20  to once again abut their respective valve seats  24  and  26 .  
         [0045]     As described above, pump assembly  8  (as shown in  FIG. 1 ) works relatively well under normal circumstances. However, when the user compresses the reservoir inadvertently through bodily movement, the pressure generated may be sufficient to remove reservoir poppet  20  and cylinder poppet  22  from their respective valve seats  24  and  26 , thus spontaneously inflating the cylinders. When sufficient force is generated against the reservoir (or a similar component) to cause the fluid pressure to exceed the resistive characteristics of poppets  20  or  22  (overcome the force of reservoir poppet spring  28  and cylinder poppet spring  30 ), an overpressure situation has occurred. Of course, the only way to release this spontaneous inflation is to manually release the check valves.  
         [0046]     In order to avoid spontaneous inflation, the present invention utilizes the overpressure created by compression of the reservoir to seal off the pump assembly output  14 . This solution can be accomplished by many different approaches, a number of which are outlined below. It should be noted that the order in which these different embodiments are presented should not be interpreted to imply any significance or importance to any one embodiment over another.  
         [0047]     Referring to  FIG. 2 , a first embodiment of the present invention is shown and described. In summary, an overpressure tolerant pump assembly  9  is provided and including a bypass passageway  38  is added to the system which couples input chamber  16  to an expansion chamber  40 . The expansion chamber  40  is provided adjacent to the rear end  44  of cylinder poppet  22 . The relatively thin portion of housing  12  that exists between common passageway  33  and expansion chamber  40  forms an abutting wall  42 . Abutting wall  42  is relatively flexible and operates very similarly to a flexible diaphragm. Importantly, the planar surface area of abutting wall  42  is greater than the area of nose  46  of cylinder poppet  22  (wherein the nose  46  is that portion of cylinder poppet  22  that would be exposed to overpressure generated by the reservoir when the cylinder poppet  22  is seated against the valve seat  26 ). This “nose” area is approximately equal to the cross sectional area of the common passageway  33 , at a point between the nose  46  and the rear end portion  47  of reservoir poppet  20 .  
         [0048]     As is shown, expansion chamber  40  forms a closed chamber which has no output. Cylinder poppet output  32  is separate from expansion chamber  40  and couples the common passageway  33  to fluid output  14 .  
         [0049]     Under normal operation, reservoir poppet  20  and cylinder poppet  22  will function in exactly the same manner as described above with reference to  FIG. 1 . When an overpressure situation occurs within the reservoir pump assembly, the present invention will appropriately deal with these pressures to avoid spontaneous inflation. When the reservoir is somehow compressed by the user, pressurized fluid is directed through fluid input  10  and into input chamber  16  (pressure is simply increased when fluid is already present). The pressurized fluid will likewise flow into (or increase pressure within) bypass passageway  38  and fill expansion chamber  40 . As pressure from the reservoir is increased, expansion chamber  40  is forced to expand, causing abutting wall  42  to press against rear end  44  of cylinder poppet  22 , thus achieving the configuration shown in  FIG. 3 .  
         [0050]     Referring now to  FIG. 3 , abutting wall  42  forces cylinder poppet  22  against valve seat  26  preventing any fluid from entering the fluid output  14  and inflating the cylinders. Even as the overpressure generated by the reservoir is sufficient to remove reservoir poppet  20  from its valve seat  24 , it will typically not be sufficient to remove cylinder poppet  22  from its valve seat  26  because the surface area of the abutting wall  42  (on the expansion chamber  40  side) is larger than the surface area of the nose  46  of cylinder poppet  22 . With equal fluid pressure being generated against both the cylinder poppet  22  and the abutting wall  42 , more force will be generated by the abutting wall  42  since it has a larger exposed surface area. As such, the overpressure is used against itself to prevent the cylinder poppet  22  from opening and spontaneously inflating the cylinders.  
         [0051]     The movement of the expansion chamber  40  causing the abutting wall  42  to engage the cylinder poppet  22  will not prevent the user from subsequently manually inflating the cylinders. Namely, when pump bulb  18  is compressed, the force generated by the compression of the fluid through pump passageway  34  will be many times greater than any overpressure generated by the reservoir. To date, it has been very difficult to monitor and determine the pressures generated in an overpressure situation since each user exhibits unique individual characteristics. Furthermore, each spontaneous inflation may result from a very different physical act on the part of the user. Pressure generated by compression of the reservoir is believed to result in a fluid pressure of up to about 3 pounds per square inch but may be as high as 6-8 pounds per square inch. Conversely, compression of the pump bulb  18  will usually generate pressures on the order of 20 pounds per square inch. Clearly, the pressure generated by compression of the pump bulb  18  is sufficient to overcome the force generated by abutting wall  42 , and allow fluid to move into the cylinders via fluid output  14 . During a subsequent decompression of pump bulb  18 , reservoir poppet  20  will be pulled away from its valve seat  24  and fluid will be drawn from bypass passageway  38  and fluid input  10  into pump chamber  36 . Thus allowing the termination chamber  40  to return to its original state.  
         [0052]     Referring to  FIG. 4 , a second embodiment of the present invention is illustrated. Once again a bypass passageway  38  is provided. Bypass passageway  38  is fluidly coupled at one end to the input chamber  16 . An expansion chamber  49  and a junction chamber  48  are provided at the opposite end of bypass passageway  38 . Cylinder poppet output  32  (which is coupled with common passageway  33 ) is fluidly coupled to junction chamber  48 . Finally, fluid output  14  is also fluidly coupled to junction chamber  48 . Disposed between junction chamber  48  and expansion chamber  49  is a flexible diaphragm  50 . During normal operation, flexible diaphragm is in the state represented by dashed lines. That is, flexible diaphragm  50  is flush against bypass passageway  38 . When manually actuated, the pressurized fluid from the pump bulb  18  is forced through common passageway  33 , bypassing cylinder poppet  22  and exiting through cylinder poppet output  32  into fluid output  14 , unhindered by flexible diaphragm  50 .  
         [0053]     During an overpressure situation, the compressed fluid is forced from the reservoir through fluid input  10  and into input chamber  16 . From input chamber  16 , the pressurized fluid travels through bypass passageway  38  and into expansion chamber  49 . The pressure generated will cause the flexible diaphragm  50  to flex to the position represented by solid lines. In this position, cylinder poppet output  32  is sealed. Thus, even if the overpressure is sufficient to dislodge the reservoir poppet  20  and the cylinder poppet  22  from their respective valve seats, fluid is prevented from entering fluid output  14  and spontaneously inflating the cylinders.  
         [0054]     Once again, the overpressure of the fluid is used against itself to prevent fluid from entering the fluid output  14 . As is illustrated, expansion chamber  49  is relatively large compared to cylinder poppet output  32 . More specifically, once the flexible diaphragm  50  is in the position represented by solid lines, a larger surface area of the flexible diaphragm  50  will then be exposed to the expansion chamber  49  than is exposed to the cylinder poppet output  32 . As such, with equal fluid pressure being generated in the bypass passageway  38 , and the cylinder poppet output  32 , a greater force will be exerted in the direction forcing flexible diaphragm  50  against cylinder poppet outlet  32 , due to the relative surface area ratios. When the user wishes to manually inflate the cylinder, a compression of the pump bulb  18  will generate force in excess of that exerted on flexible diaphragm  50  through bypass passageway  38 .  
         [0055]      FIG. 5  illustrates a variation of the embodiment illustrated in  FIG. 4 . Here the flexible diaphragm  50  flexes between sealing the bypass passageway  38  and sealing the fluid output  14 . Sealing the fluid output  14  effectively prevents fluid from exiting cylinder poppet output  32  and entering fluid output  14 . Once again it is the amount of fluid surface area within expansion chamber  49  that is in contact with flexible diaphragm  50  versus the amount of fluid surface area in and around junction chamber  48  (also in contact with flexible diaphragm  50 ) that results in a sufficient force differential to seal fluid output  14 .  
         [0056]     In both the embodiments shown in  FIGS. 4 and 5 , it should be noted that if pressurized fluid were to exit out through cylinder poppet output  32  and thus exert a force against flexible diaphragm  50  before sufficient force was generated through bypass passageway  38 , the sealing effects of flexible diaphragm  50  would effectively be bypassed and spontaneous inflation could occur. However, as is readily apparent from the illustrations, this will not happen. As overpressurization occurs in the reservoir, pressurized fluid is directed through fluid input  10  and into input chamber  16 . The path of least resistance will be through bypass passageway  38  rather than displacing reservoir poppet  20  and cylinder poppet  22  from their respective valve seats. As such, flexible diaphragm  50  will always be flexed to its sealing position when an overpressure situation occurs, and this displacement will occur before either poppet  20  or  22  is displaced allowing fluid to flow through cylinder poppet output  32 .  
         [0057]     Referring to  FIG. 6 , a third embodiment of the present invention is illustrated. Bypass passageway  38  fluidly couples input chamber  16  to a compression chamber  52 . Compression chamber  52  surrounds a portion of fluid output  14 . If not already sufficiently flexible, the portion of the fluid output  14  within compression chamber  52  can be formed from a flexible, easily compressible material. During an overpressure situation, compressed fluid from the reservoir is forced through fluid input  10  and into input chamber  16 . The compressed fluid flows through bypass passageway  38  and into compression chamber  52  where it compresses compressible tube  54  (which is that section of fluid output  14  within compression chamber  52 ). The amount of surface area on the outer surface of compressible tube  54  will necessarily be greater than the surface area within the compressible tube  54 . As such, the force generated will be greater in a direction compressing compressible tube  54  than a counterforce trying to expand it. As such, when an overpressure situation occurs, compressible tube  54  is collapsed, sealing fluid output  14  from the cylinders and preventing spontaneous inflation.  
         [0058]      FIG. 7  illustrates a fourth embodiment of the present invention. This embodiment has several elements that are in common with the previously described embodiments. Namely input chamber  16  is fluidly coupled to fluid output  14  via common passageway  33 . Common passageway  33  is impeded by a reservoir poppet  20  and cylinder poppet  22  which are both spring biased to seat against their respective openings. The area between the nose of cylinder poppet  22  and the rear portion of reservoir poppet  20  is referred to as intermediate chamber  62 .  
         [0059]     The intermediate chamber  62  is fluidly coupled to a return channel  65  which is in fluid communication with expansion chamber  40 . A return check valve  75  is provided within return channel  65  and only allows fluid flow from expansion chamber  40  to intermediate chamber  62 . A bypass channel  60  is provided and fluidly couples input chamber  16  to return channel  65 . As indicated the junction between the bypass channel  60  and return channel  65  occurs between expansion chamber  40  and return check valve  75 . A bypass check valve  70  is provided within bypass channel  60  and only allows fluid flow in the direction from input chamber  16  to expansion chamber  40 .  
         [0060]     When an over-pressurization situation occurs, fluid pressure within input chamber  16  increases. This higher pressure fluid travels through bypass channel  60  and unseats bypass check valve  70 . From here the pressurized fluid flows into the return channel  65  and into expansion chamber  40  or alternatively it unseats return check valve  75  and enters intermediate chamber  62 . As fluid pressure is increased abutting wall  42  is caused to deflect due to the expansion of expansion chamber  40  and firmly abuts cylinder poppet  22  causing it to form a tight seal. Similarly fluid pressure levels within intermediate chamber  62  can increase, however, as previously discussed due to the differences in relative surface area the force exerted within expansion chamber  40  against abutting wall  42  will always be greater than that exerted against the nose of cylinder poppet  22 , thus preventing spontaneous inflation.  
         [0061]     As fluid pressures within input chamber  16  decrease the elevated fluid pressure level within intermediate chamber  62  cause reservoir poppet  20  to firmly seal and also cause return check valve  75  to firmly seal. (Assuming equal pressure within expansion chamber  40  and intermediate chamber  62 ). Bypass check valve  70  is also likewise sealed. Thus, the higher pressure fluid within expansion chamber  40  is effectively trapped and cannot exit unless the fluid pressure levels within intermediate chamber  62  are reduced which would allow return check valve  75  to open. In other words, fluid pressures within expansion chamber  40  will always be greater or equal to the fluid pressure levels within intermediate chamber  62 .  
         [0062]     With this embodiment fluid pressure levels within intermediate chamber  62  are only reduced when pump bulb  18  is actuated forcing cylinder poppet  22  to unseat itself and causing the cylinders to be inflated. Alternatively, housing  12  could be engaged in the manner described above to deflate the cylinders. That is manually actuating reservoir poppet  20  to disengage cylinder poppet  22 . The release of reservoir poppet  20  would allow pressurized fluid within intermediate chamber  62  to reenter input chamber  16 .  
         [0063]     As fluid pressure levels within input chamber  16  increase the forces generated could either unseat reservoir poppet  20 , thus allowing entry into intermediate chamber  62  or they could unseat bypass check valve  70 , allowing fluid communication with expansion chamber  40 . It is desirable to have fluid communication with expansion chamber  40  prior to fluid communication with intermediate chamber  62 . Thus bypass check valve  70  is configured to open at lower pressures than reservoir poppet  20 . As fluid pressures increase within input chamber  16  fluid will follow the path of least resistance, thus opening bypass check valve  70 . Subsequently pressures may be sufficient to also open reservoir poppet  20 , but the system will continue to work properly inasmuch as expansion chamber  40  is already expanding.  
         [0064]     A fifth embodiment of the present invention is illustrated in  FIG. 8 . A return channel  65  is provided which fluidly couples input chamber  16  to expansion chamber  40 . Intermediate chamber  62  is fluidly coupled to return channel  65  via intermediate chamber passageway  64 . Located within return channel  65  are a return check valve  75  and a fluid resistor  80 . Return check valve  75  is positioned between intermediate chamber passageway  64  and expansion chamber  40  while fluid resistor  80  is positioned between intermediate chamber passageway  64  and input chamber  16 . Bypass channel  60  is provided and fluidly couples input chamber  16  with return channel  65  wherein the junction between bypass channel  60  and return channel  65  occurs between the return check valve  75  and expansion chamber  40 . Located within bypass channel  60  is a bypass check valve  70  that only allows fluid flow in the direction from input chamber  16  to expansion chamber  40 . Return check valve  75  allows fluid flow from the direction of expansion chamber  40  towards both intermediate chamber  62  and input chamber  16 .  
         [0065]     As fluid pressures within input chamber  16  increase bypass check valve  70  is caused to be unseated allowing fluid flow into expansion chamber  40  as previously described. The cracking pressure required to unseat bypass check valve  70  is lower than that required to unseat reservoir poppet  20 . Thus, pressurized fluid is caused to flow from input chamber  16  through bypass channel  60  and into expansion chamber  40 , and if sufficient pressures are reached return check valve  75  can be unseated and pressurized fluid can enter intermediate chamber  62 . Once again as pressure levels within expansion chamber  40  increase, abutting wall  42  is caused to deflect which in turn causes cylinder poppet  22  to firmly seal preventing spontaneous inflation.  
         [0066]     As illustrated, input chamber  16  is in fluid communication with return channel  65 . However, fluid resistor  80  is positioned between input chamber  16  and intermediate chamber  62 . Fluid resistor  80  is a narrowing of a fluid passageway restricting fluid flow, a lengthening of the fluid path, or a combination of the two. Fluid resistor  80  could be a separate component added to the structure, rather than a modification of the existing passageway. Thus, during an over-pressurization situation fluid flow from input chamber  16  into intermediate chamber  62  through fluid resistor  80  is trivial. Conversely, during a compression of pump bulb  18 , fluid resistor  80  will allow a small amount of bleed through into input chamber  16 . This has a very negligible effect on pumping. As described with reference to the fourth embodiment, pressure levels within expansion chamber  40  and intermediate chamber  62  can each reach relatively high levels. Return check valve  75  will only allow pressurized fluid within expansion chamber  40  to exit when pressure levels within intermediate chamber  62  and the corresponding portion of return channel  65  are lower than that within expansion chamber  40 . To allow this to occur fluid resistor  80  slowly allows pressurized fluid within intermediate chamber  62  to bleed back into input chamber  16 . Over time pressure levels within intermediate chamber  62  and input chamber  16  will reach stasis. As pressure levels within intermediate chamber  62  are reduced, higher pressure fluid from expansion chamber  40  will unseat return check valve  75  and also eventually pass through fluid resistor  80  back into input chamber  16  returning the entire system to equilibrium.  
         [0067]     A sixth embodiment is shown with reference to  FIG. 9 . A return channel  65  is provided and fluidly couples input chamber  16  to expansion chamber  40 . Intermediate chamber  62  is also fluidly coupled to return channel  65  via intermediate chamber passageway  64 . Located between input chamber  16  and intermediate chamber passageway  64  is a reservoir side fluid resistor  90 . Located between intermediate chamber passageway  64  and expansion chamber  40  is a cylinder side fluid resistor  85 . Bypass channel  60  is provided and fluidly couples input chamber  16  to expansion chamber  40 , effectively bypassing both fluid resistors  85  and  90 . Bypass check valve  70  is provided within bypass channel  60  and allows fluid flow in the direction from input chamber  16  to expansion chamber  40 .  
         [0068]     As an over-pressurization situation occurs, pressurized fluid from input chamber  16  flows through bypass channel  60  and unseats bypass check valve  70  allowing fluid entry into expansion chamber  40 . Pressurized fluid causes abutting wall  42  to deflect, thus sealing cylinder poppet  22  and preventing spontaneous inflation. Bypass check valve  70  has a lower cracking pressure than reservoir poppet  20  encouraging fluid flow through bypass channel  60  and into expansion chamber  40  prior to unseating reservoir poppet  20  and allowing pressurized fluid to flow into intermediate chamber  62 . While return channel  65  is in fluid communication with both intermediate chamber  62  and expansion chamber  40 , initially pressurized fluid from reservoir  16  will not quickly enter either of these two areas through return channel  65  due to restricted fluid flow through cylinder side fluid resistor  85  and reservoir side fluid resistor  90 .  
         [0069]     Once fluid pressure levels within input chamber  16  are reduced, high pressure fluids within intermediate chamber  62  will slowly bleed through reservoir side resistor  90  and into input chamber  16 . As this occurs fluid pressure levels within return channel  65  will slowly decrease. When fluid pressure levels within return channel  65  on the input chamber side of cylinder side fluid resistor  85  are lower than that within expansion chamber  40 , pressurized fluid will slowly bleed through cylinder side resistor  85  and eventually return to input chamber  16 . Once again this system always maintains a higher pressure level within expansion chamber  40  than is maintained in intermediate chamber  62 . Just as with the previous embodiment, there will be a small amount of pressure bleed through reservoir side resistor  90  into input chamber  16 . This will have a negligible effect on pumping.  
         [0070]     Referring to  FIG. 10 , a seventh embodiment to the present invention is illustrated. A bypass fluid passageway  38  fluidly couples input chamber  16  to expansion chamber  40 . Located within bypass passageway  38  is a high impedance fluid resistor  95 . Intermediate chamber passageway  64  fluidly couples intermediate chamber  62  to bypass passageway  38 . Located within intermediate chamber passageway  64  is a low impedance fluid resistor  100 . It is to be understood that with reference to fluid resistors  95  and  100  the terms high and low are with respect to one another. That is fluid resistor  100  has a lower fluid impedance than fluid resistor  95 . In other words, a higher volume of fluid will travel through low impedance resistor  100  than through high impedance resistor  95  in the same amount of time when under the same pressure. Bypass channel  60  is provided and is coupled to bypass passageway  38 , effectively bypassing the high impedance fluid resistor  95 . Bypass check valve  70  is located within bypass channel  60  and only allows fluid flow in the direction from the input chamber  16  to expansion chamber  40 . The cracking pressure of bypass check valve  70  is set such that when an over-pressurization situation occurs the path of least resistance from input chamber  16  is to enter bypass passageway  38 , open bypass check valve  70 , and enter expansion chamber  40 . Pressurized fluid may eventually be able to unseat reservoir poppet  20  or flow through low impedance resistor  100  and enter intermediate chamber  62 . However, the abutting wall  42  is displaced by the movement of expansion chamber  40  under increased fluid pressures causing cylinder poppet  22  to seal tightly preventing spontaneous inflation.  
         [0071]     When fluid pressures are reduced in input chamber  16  high pressure fluid contained within intermediate chamber  62  passes more quickly through low impedance resistor  100  than would pass through high impedance resistor  95 . Hence, intermediate chamber  62  empties at a faster rate. In addition, fluid will only travel from expansion chamber  40  through high impedance resistor  95  when fluid pressure levels within bypass passageway  38  adjacent input chamber  16  are sufficiently low. That is, lower than that within expansion chamber  40 . This fact coupled with the ability of the intermediate chamber  62  to reduce pressure levels more quickly will always assure that pressure levels within expansion chamber  40  are higher than that within intermediate chamber  62  once again preventing spontaneous inflation. During pumping, a small amount of pressurized fluid will pass through low impedance resistor  100 , however the effect will be negligible.  
         [0072]      FIG. 11  represents an eighth embodiment of the present invention. As illustrated, housing  12  has been slightly modified to accommodate a variety of additional internal passageways. Fluid input  10  is coupled with a reservoir at one end and reservoir chamber  16  at the other. Located within housing  12 , and coupled to fluid input  10  prior to reservoir chamber  16 , is an overpressure chamber  156 . Optionally, overpressure chamber  156  has an overpressure chamber input  158  having a narrowed opening. Cylinder poppet output  32  leads into an output passageway  160 . Output passageway  160  leads to a first output chamber  162  and a second output chamber  164  (actually two parts of a single chamber or passage way). The fluid output  14  is fluidly coupled to the first output chamber  162 . Interconnecting the output passageway  160  to the first output chamber  162  is a relatively narrow throat portion  166 . The first output chamber  162  and the second output chamber  164  are located proximate the overpressure chamber  156  within housing  12 . Separating first output chamber  162  and second output chamber  164  is a compression wall  167  with a sealing extension  168  which also forms a portion of the narrow throat portion  166 . During an overpressure situation, fluid pressure is increased in overpressure chamber  156 , thus causing it to expand. The expansion of overpressure chamber  156  causes the compression wall  167  and sealing extension  168  to move, thus sealingly abutting throat  166  and effectively preventing fluid from flowing through output passageway  160 . Preferably, compression wall  167  is configured so that a maximum amount of movement results from the force generated, thus effectively sealing throat  166 .  
         [0073]     Referring to  FIG. 12 a  ninth embodiment to the present invention is illustrated. This embodiment can be used as shown or can be coupled with any of the previously described embodiments. Generally the housing  12  of the valve assembly will be made of a flexible material such as silicone. As such if external pressures are applied to housing  12  in an undesired manner, it may be possible to unseat poppets  20 ,  22  which may lead to spontaneous inflation. To prevent an inadvertent compression of housing  12  from causing spontaneous inflation, a rigid insert is incorporated into housing  12  to eliminate this degree of flexibility.  
         [0074]     As shown in  FIG. 12 a  solid cylindrical element  105  is incorporated within housing  12  and surrounds reservoir poppet  20  and cylinder poppet  22 . Thus, inadvertent compression of housing  12  will be unable to displace reservoir poppet  20  or cylinder poppet  22 . Of course, to function properly the user must be able to manually displace reservoir poppet  20  by compressing the side walls of housing  12 , and this function is maintained.  
         [0075]     Since the housing  12  for the valve assembly is generally molded, it may be desirable to have cylindrical element  105  in place during the fabrication process by including a plurality of holes  110  in cylindrical element  105  and placing cylindrical element  105  in the mold during fabrication. Cylindrical element  105  will in effect be molded in place and holes  110  allow the material being utilized (i.e. silicone) to flow through cylindrical element  105  and properly define housing  12 . While shown as being cylindrical, element  105  can be formed into any appropriate shape for the valve assembly being utilized.  
         [0076]     In general the present invention utilizes an outlet sealing mechanism that relies on the overpressure generated by a compression of the reservoir (or similar component) to also seal the output. That is, the overpressure generated is effectively used against itself to prevent fluid from entering the cylinder and producing a spontaneous inflation. While various embodiments have been shown and described which utilize this effect, it is to be understood that any such utilization of the overpressure to prevent fluid flow to the cylinders is within the scope and spirit of the present invention, and as such, the present invention is not intended to be limited only to those specific embodiments shown and described herein.  
         [0077]     While the present invention has been described with respect to a pump and valve assembly for a penile implant, the use of generated overpressure to seal a fluid aperture has many other applications within the scope and spirit of the present invention. For example, artificial sphincters utilize fluid pressure to maintain a body cavity or natural passageway in a closed or sealed state. When actuated, fluid pressure is released from the sphincter, causing the bodies&#39; passageway to open. As such, the fluid pressure generated could be used to assist the artificial sphincter in either state. Likewise, many other uses for an overpressure seal exist, both specifically within the field of medical devices and within the field of fluid/gas handling devices in general.  
         [0078]     Those skilled in the art will further appreciate that the present invention may be embodied in other specific forms without departing from the spirit or central attributes thereof. In that the foregoing description of the present invention discloses only exemplary embodiments thereof, it is to be understood that other variations are contemplated as being within the scope of the present invention. Accordingly, the present invention is not limited in the particular embodiments which have been described in detail therein. Rather, reference should be made to the appended claims as indicative of the scope and content of the present invention.