Patent Publication Number: US-6217085-B1

Title: Connection for a compressed gas attachment device and compressed gas cartridge

Description:
BACKGROUND OF THE INVENTION 
     A stopper attachment device with a compressed gas-propelled plunger is supplied with compressed gas, generally formed by a mixture of butane and propane, from a fuel cartridge containing, in an internal casing, gas compressed to the liquid state, referred to as “fuel” by persons skilled in the art. In addition to the fuel, the cartridge contains, between the internal casing and an external casing, a propellant formed from a mixture of nitrogen, butane and propane in the gaseous state and also intended to keep the fuel in the liquid state. A male ejection joining piece is connected to the internal casing and protrudes out of the external casing. 
     Upon each firing of the stopper a predetermined dose of compressed gas is injected from the fuel cartridge into a combustion chamber of the attachment device, the dose being controlled only if the compressed gas is metered in the liquid state. 
     In order to meter the compressed gas injected into the combustion chamber, certain attachment devices such as that disclosed in EP-0775 553A1 comprise a solenoid valve including a female joining piece for inletting compressed gas, with an integrated seal arranged in order to receive the male ejection joining piece of the fuel cartridge, the seal being intended to ensure sealing tightness of the connection between the two joining pieces. For each injection of fuel the solenoid valve is opened for a specific duration to meter fuel through, the inlet joining piece of the solenoid valve having a specific cross-section. In order to prevent possible fuel leaks, it would be appropriate to regularly change the seal which provides the sealing tightness of the solenoid valve-cartridge connection. However, changing a seal of this type has proven to be a complicated operation which, in practice, is never carried out. 
     It is an object of the invention to facilitate the operation of changing the seal for sealing the connection between the fuel cartridge and the solenoid valve for inletting compressed gas into the device. 
     SUMMARY OF THE INVENTION 
     The invention relates to a connection, on the one hand, for a male ejection joining piece of a fuel cartridge intended to supply compressed gas to a compressed gas attachment device and, on the other hand, for an inlet joining piece of a device for inletting compressed gas into the device, comprising a sealing arrangement to ensure sealing tightness of the connection between the two joining pieces. In accordance with the invention the joining piece of the compressed gas inlet device is a male joining piece, and the connection comprises a female seal support arranged to receive the two male joining pieces and the sealing arrangement are arranged to extend right across the seal plane of the two male joining pieces. 
     The invention is thus directed to relocating the seal which is no longer integrated into the inlet joining piece as in the prior art but is supported by a seal support which can be easily changed each time the fuel cartridge is changed. 
     The sealing arrangement can comprise a seal in the form of a sleeve arranged to surround the two male joining pieces. 
     In this case the seal can comprise an internal groove for retaining leaked gas. Thus, in the case of a leak, only a small volume of gas is lost 
     The sealing arrangement can also comprise two O-rings respectively intended to surround the two male joining pieces. 
     The seal support is advantageously arranged to guide the two male joining pieces in such a way as to cause them to abut against each other. 
     For this reason it will suffice to introduce the two joining pieces to be connected into the seal support in-order to connect them. 
     It is also advantageous that the seal support comprises means for attachment to the fuel cartridge. 
     The fuel cartridge comprising a border, the attachment means can comprise at least two hooked legs arranged to be clipped on the border of the cartridge. 
     The invention also relates to an assembly comprising a fuel cartridge and connection means as defined above, wherein the connection means are firmly fixed to the fuel cartridge. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be better understood with the aid of the following description of different embodiments of the connection of the invention, with reference to the attached drawing in which: 
     FIG. 1 is a perspective view of a first embodiment of the connection; 
     FIG. 2 is illustrates a side view of the connection of FIG. 1; 
     FIG. 3 is illustrates a cross-sectional view of the connection of FIG. 1 taken along the line III—III; 
     FIG. 4 is a cross-sectional view of the connection of FIG. 1 used to connect two joining pieces and 
     FIG. 5 is a cross-sectional view of a second embodiment of the connection used to connect two joining pieces and 
     FIG. 6 is a cross-sectional view of a third embodiment of the connection. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A stopper attachment device with a compressed gas-propelled plunger comprises a combustion chamber intended to be supplied with compressed gas from a fuel cartridge  20 . 
     In the particular example of the description the connection is intended to connect a solenoid valve  30 , for inletting compressed gas into the combustion chamber of the attachment device, and the compressed gas cartridge  20 . 
     Referring to FIG. 4, the cartridge  20 , which is generally cylindrical in shape, comprises, inside an internal casing, gas compressed to the liquid state, referred to as “fuel” by the person skilled in the art, and, between the internal casing and an external casing, a propellant. A circular border  21  extends as an extension of the external cylindrical wall of the cartridge  20  at one end thereof. A male ejection joining piece  23 , connected to the internal casing, protrudes out of the cartridge by means of a projection  24  located at the centre of the circle described by the border  21 . 
     The solenoid valve  30 , which is generally cylindrical in shape, comprises an inlet duct  31  communicating by one of its ends with an inlet joining piece  32 , a filter  33  being interposed, and by its other end with a metering chamber  34 . The solenoid valve  30  also comprises an outlet duct  35  connected by one of its ends to an outlet joining piece  36  and by its other end to the metering chamber  34 . The inlet duct  31  and outlet duct  35  communicate with the metering chamber  34  respectively by two orifices disposed opposite each other. 
     A spring washer  37  firmly fixed to a closure seal  39  is mounted inside the metering chamber  34  by its outer peripheral edge being introduced into a slit provided in the inner wall of the chamber  34 . 
     The solenoid valve  30  also comprises an electromagnet  38  under the action of which the closure seal  38  can move from an inlet position to an outlet position by slight deformation of the spring washer  37 . In the inlet position the closure seal  38  closes the orifice of the outlet duct  35  while the orifice of the inlet duct  31  is released and, in the outlet position, the closure seal  38  closes the orifice of the inlet duct  31  while the orifice of the outlet duct  35  is released. 
     The inlet joining piece  32  of the solenoid valve is a male joining piece surrounded by a bushing provided in this case with four lateral slits intended to receive a vent shaft  3  of the connection as will be explained hereinunder. 
     Referring additionally to FIG. 1, the connection comprises a female seal support  1  intended to receive the male ejection joining piece  23  of the fuel cartridge  20  and the male inlet joining piece  32  of the solenoid valve  30 . 
     The seal support  1 , which is a single piece of plastics material, comprises a planar abutment base  2 , in this case substantially rectangular, supporting the vent shaft  3  which houses a seal  11  and is open at its two ends and extends along an axis  15  perpendicular to the abutment base  2 , at one side thereof. The edge  4  of the free end of the vent shaft  3  turns back at a right angle towards the inside of the vent shaft  3  and forms an orifice for passage of the inlet joining piece  32  of the solenoid vale  30 , having a cross-section substantially equal to that of the joining piece  32 . 
     Two attachment legs  5 ,  6 , which are connected to the abutment base  2  by one of their ends and are symmetrical to each other with respect to an axis  15 , extend in two mutually parallel planes perpendicular to the abutment base  2  on the side opposite that of the vent shaft  3 . The spacing between the two legs  5 ,  6  is substantially equal to the inner diameter of the border  21  of the fuel cartridge  20 . Moreover, the two legs  5 ,  6  are each provided, at their free end, with a hook intended to hook onto the inner wall of the border  21 . 
     The abutment base  2  comprises two pairs of abutment fingers  7 - 10  extending in the plane of the base  2 . The two fingers  7 - 8  ( 9 - 10 ) of each pair are located on either side of the end where one of the attachment leas  5 , ( 6 ) is connected to the base  2  and beyond the plane in which the leg  5  ( 6 ) extends with respect to the axis  15 . 
     The seal  11  housed in the vent shaft  3  is in this case in the form of a sleeve and presents an inner groove  12  for retaining leaked gas. The seal  11  is held between the edge of the turned-back free end  4  of the vent shaft  3  and a retention ring  13  introduced into the vent shaft  3  by its orifice through the abutment base  2 . The retention ring  13  comprises an inner wall  14  having a truncated portion widening towards the outside of the vent shaft and intended to facilitate guidance of the ejection joining piece  23  of the fuel cartridge  20  when it is introduced into the vent shaft  3 , and another portion  14 ′, adjacent to the seal  11 , which is cylindrical in shape with a cross-section substantially equal to that of the ejection joining piece  23  and intended to guide and retain the joining piece  23 . 
     The connection of the inlet joining piece  32  of the solenoid valve  30  and the ejection joining piece  23  of the fuel cartridge  20  will now be described. 
     In order to mount the connection on the fuel cartridge  20  the attachment legs  5 ,  6  are inserted into the border  21  of the cartridge  20  until the abutment fingers  7 - 10  abut against the border  21 . The hooks of the legs  5 ,  6  hook and clip onto the inner wall of the border  21 . In this position, the ring  13  projects slightly out of the vent shaft  3  and is in abutment against arrangement projection  24 , ensuring the retention of the seal  11  in position inside the vent shaft  3 . 
     During attachment of the connection to the cartridge  20 , the ejection joining piece  23  of the cartridge  20  is guided into the vent shaft  3  by the inner walls  14 ,  14 ′ of the retention ring  13 . 
     The vent shaft  3  of the connection is then introduced into the bushing  40  of the solenoid valve  30  until the edge of the free end of the bushing  40  abuts against the abutment base  2  of the connection. During introduction of the vent shaft  3  of the connection into the bushing  40  the male inlet joining piece  32  of the solenoid valve  30  is guided into the vent shaft  3  by the edge of the turned-back end  4 . 
     The two male joining pieces  23 ,  32  guided into the vent shaft  3 , abut against each other and the seal  11  surrounds the two joining pieces  23 ,  32 , extending right across the seal plane of the two joining pieces  23 ,  32 . 
     When inoperative, the closure seal  38  of the solenoid valve  30  is in the inlet position. In this position compressed gas escapes from the fuel cartridge  20  by way of the ejection joining piece  23 , passes into the solenoid valve  30  by way of the inlet joining piece  32  and fills the metering chamber  34  after passing through the filter  33  and into the inlet duct  31 . 
     The seal  11  ensures the sealing tightness of the connection of the two joining pieces  23 ,  32 . In the case of a possible leak of gas this gas will remain in the inner groove  12  of the seal which, in any case, is of a limited volume. 
     In order to supply the combustion chamber of the attachment device with compressed gas the outlet joining piece  36  is connected to the combustion chamber. The electromagnet  39  is actuated and under its action the spring washer  37  is slightly deformed and moves the closure seal  38  from its inlet position to its outlet position. The gas contained in the metering chamber  34  thus escapes towards the outlet joining piece  36  by way of the outlet duct  35 . The electromagnet  39  is then shut off and the closure seal returns to the inlet position. 
     In order to inject the desired quantity of compressed gas into the combustion chamber of the attachment device, the closure seal  38  is thus caused to perform a reciprocating movement between its inlet position and its outlet position. 
     The seal  11 , which is in the form of a sleeve, could also be replaced by two O-rings  16 ,  17 , respectively intended to surround the two male joining pieces  32 ,  23  and thus to extend right across the seal plane of the two joining pieces  32 ,  23 . In this case a piece  18  forming a spacer is interposed between the two seals in such a way as to position them correctly as shown in FIG.  5 . 
     In another embodiment of the connection  50 , the seal  51 , in the form of a sleeve, and the retention ring  52  are formed in a single piece. 
     Provision could also be made to fix the connection and the fuel cartridge firmly together.