Vacuum position sensing device

Abstract

An apparatus and method of controlling a machine for filling pharmaceutical syringes with fluid. The apparatus consists of a vacuum source, a vacuum adapter, a vacuum switch, a filling needle housing and a filling needle that are to be located over a syringe. In the event of misalignment of the filling needle over the syringe and the needle contacts the top of the syringe or the syringe tray, the housing rises and uncovers the connecting pipe causing loss of vacuum. This loss of vacuum at the vacuum switch shuts down the machine.

Description

FIELD OF THE INVENTION

This invention relates to a method and apparatus for sensing the correctly placed position of an element in a machine wherein the method uses a vacuum source and a vacuum pressure sensing instrument to deactivate the machine when the element is moved to an improper position. A specific application of this device is use in a machine used for filling pharmaceutical syringes with fluid.

BACKGROUND OF THE INVENTION

Machinery for filling and closing pharmaceutical syringes must comply with the FDA cleanliness and volume accuracy guidelines. In addition they need to be fast to provide a product that is competitive in the marketplace. To meet these requirements the industry has developed machines that can fill and close syringes at a rate of 50 syringes per minute or more. When the price of the filling fluid approaches $1200 or more for each syringe fill, one syringe tray in a machine can be worth over $100000 alone. It is therefore mandatory that machine malfunction be detected before filling errors spoil a batch or tray fill of syringes. An error that can occur is misalignment by a positioning machine that incorrectly spots a filling needle housing over a particular syringe and moves the filling needle down at the wrong position striking the syringe or part of the holding tray. Prior art devices sensed this error by sensing movement of the needle holder using electrical contacts in a circuit that contacted the needle holder and then stopped the machine. This type of device operated properly until contact corrosion caused electrical malfunction of the sensing circuit.

It is the purpose of this invention to disclose an apparatus that can sense improper contact by a syringe filling needle and stop needle motion in a syringe filling machine. The apparatus can be used in any application where incorrect motion is detected by a loss of vacuum in the apparatus or machine.

SUMMARY OF THE INVENTION

The device consists typically as part of a syringe filling machine. This device comprises two movable pipe connections that support a vacuum adapter, filling needle housing, filling needle and a sealing element above a tray of syringes. The pipe connections attach to a remote vacuum source and an upper pipe has a vacuum switch at a tee connection in this pipe adjacent to the vacuum adapter.

The function of the machine is to center the filling needle over the syringe while maintaining a vacuum in the upper pipe, lower the needle housing and needle until the sealing element contacts the top of the syringe, draw a vacuum in the syringe and then fill the syringe. On completion of the filling, the apparatus raises and traverses to the next syringe and the process is repeated.

In the case where a misalignment occurs of the needle over a syringe, as the needle housing and needle go down the needle will contact the edge of the syringe or part of the supporting tray. Contact of the needle with any object will move the needle vertically within the filling needle holder, opening a port to the upper pipe causing a loss of vacuum in that upper pipe. The vacuum switch senses that loss and stops down motion of the needle. This prevents damage to the needle, tray and other machine parts. It is the novel use of the vacuum switch sensing loss of vacuum in the holder and stopping motion that is the purpose of this invention. The described apparatus can be used in any machine that has moving objects within a closed holding containment. The method and apparatus can be used in a machine that fills multiple syringes simultaneously or one or two syringes simultaneously but will be described for a single syringe filling apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side section schematic view of the apparatus used to fill a syringe showing the present invention in a first correct position of a filling needle over a syringe.

FIG. 2 is a section view of the apparatus in a second incorrect position of the filling needle over the syringe.

DETAILED DESCRIPTION OF THE INVENTION

The invention will be described by referring to the apparatus illustrated in FIGS. 1 and 2. In FIG. 1 the syringe 10 is shown before engagement with seal element 12 attached at the bottom of cylindrical vacuum adapter 14 which holds the filling needle 16 and cylindrical filling needle housing 18. Filling needle housing 18 has upper and lower O-rings 20 or seals spaced apart on its' circumference. The vacuum adapter 14 has two pipe or conduit connections connecting to upper and lower sections of the adapter. The lower connection is the fill vacuum pipe 22 and the upper pipe is the holding vacuum pipe 24. A tee connection in the holding vacuum pipe 24 is attached to a vacuum sensing switch 26 in communication with the pressure in pipe 24. Fluid is delivered to the adapter 14 needle 16 and syringe 10 via flexible filling tube 28.

FIG. 1 shows the apparatus as it descends over syringe 10 in proper alignment with the syringe. All parts are moving simultaneously as the needle 16 prepares to enter the syringe 10 and a vacuum P2 in the upper pipe 24 is holding the needle housing 18 and needle16 in position. The vacuum switch 26 senses this vacuum and permits down motion of the entire assembly as shown by arrow 30.

In FIG. 2 the entire filling assembly is misaligned over the syringe10 and the filling needle 16 has contacted the edge of the syringe. The continued down motion of the assembly shown at arrow 32, has caused the needle 16 and housing 18 to be displaced upward relative to the descending vacuum adapter 14. This displacement of the housing 18 and O-rings 20 above the upper pipe 24 causes a loss of vacuum at P2. The vacuum switch 26 senses the loss of vacuum and stops the down motion of the machine. Operator correction of the problem is required to continue machine operation but critical damage has been avoided by use of this vacuum sensing device.

Claims

1) A machine having an apparatus that monitors the location of a piston within a cylinder, the apparatus comprising:

a) a conduit connected to the side of the cylinder;

b) a vacuum switch connected to the conduit in communication with the space within the cylinder;

c) a vacuum source connected to the conduit;

d) an upper and lower seal on the circumference of the piston wherein movement of the piston such that the lower seal is above the conduit connection, a corresponding loss of vacuum in the conduit and pressure switch affects operation of the machine.

2. The machine and apparatus of claim 1 wherein the machine is a pharmaceutical syringe filling machine.

3. The machine and apparatus of claim 2 wherein the piston is a filling needle housing having a filling needle attached at a lower portion.

4. The machine and apparatus of claim 3 wherein the cylinder is a vacuum adapter.

5. The machine and apparatus of claim 3 wherein movement of the filling needle housing lower seal above the conduit connection causes loss of vacuum and machine shutdown.

6. A machine and apparatus for filling pharmaceutical syringes, the apparatus comprising:

a) a vacuum adapter having a connecting holding vacuum conduit;

b) a tee connection on the vacuum conduit connected to a vacuum switch;

c) a cylindrical needle housing within the vacuum adapter;

d) a filling needle attached at a lower end of the needle housing;

e) an upper and lower seal attached to the circumference of the housing;

f) a vacuum source connected to the vacuum conduit wherein needle contact with any object raises the needle and housing thereby moving the lower seal above the vacuum conduit causing loss of vacuum and shutdown of the machine by the vacuum switch.

7. A method of controlling a machine for filling pharmaceutical syringes, the machine comprising a vacuum adapter containing a needle housing and fill needle, a holding vacuum conduit connected to the vacuum adapter, a vacuum switch connected to the vacuum conduit, a vacuum source connected to the vacuum conduit and an upper and lower seal on the circumference of the needle housing, the method comprising:

a) maintaining a vacuum on the holding vacuum conduit and space between the seals to hold the needle housing in position; and

b) moving and lowering the conduit, vacuum adapter, needle housing and needle over a syringe wherein an inadvertent misalignment of the needle housing, needle and vacuum adapter causes the needle and housing to raise relative to the lower seal creating a loss of vacuum thereby activating the vacuum switch to shutdown the machine.