Abstract:
An improved grease supply cartridge is provided for pressure actuated dispensers, which contains the grease to be dispensed in a relatively rigid cylindrical paperboard body fitted with a piston formed of thin-walled flexible plastic material that reacts with particular effectiveness under the pressure applied for dispensing to exhaust the cartridge supply completely and advantageously.

Description:
BACKGROUND OF THE INVENTION 
     Pressure-actuated grease dispensers have been in use for some time to lubricate industrial machines, such as looms in textile mill weave rooms. The dispensers commonly comprise a pressure chamber to which compressed air is fed for actuating the dispensing and in which a grease supply cartridge is inserted with a piston covering the grease supply that is forced by the air pressure to dispense the grease from the cartridge. Difficulty has been encountered, however, in providing the supply cartridges for reliable operation so that the piston consistently forces the grease supply for dispensing without bypassing grease wastefully or allowing air to leak into the grease to form an air lock that causes the dispenser to become inoperative. 
     The present invention solves this problem by providing grease supply cartridges for such dispensers that are uniquely suited for dependable use. 
     SUMMARY OF THE INVENTION 
     The improved grease supply cartridge of the present invention combines a relatively rigid cylindrical laminated paperboard body loaded with grease and having a closure member fixed at one end of the body with a removable cap carried therein for providing an exit port for dispensing the grease together with a piston in the body covering the grease that is formed of a thin-walled flexible plastic material. The cup-shaped piston has an upstanding peripheral flange that is gently flared outwardly with the flange edge having an outside diameter at the top slightly larger than the inside diameter of the cartridge body. As a result, the dispensing pressure induces an airtight contact of the piston within the cartridge body that provides consistently effective dispensing action. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a vertical section illustrating the general arrangement of a pressure actuated-grease dispenser; 
     FIG. 2 is a vertical section of a grease supply cartridge as provided for insertion in the FIG. 1 dispenser; and 
     FIG. 3 is a horizontal section as seen substantially at the line 3--3 in FIG. 1. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 of the drawings shows the pressure chamber 10 of the dispensing device having a dished bottom 12 for withstanding pressure and a detachable lid 14 fixed in place by bolts 16 and having handles 18 for manipulation whenever a grease supply cartridge has to be inserted, together with a fitting 20 at which an air supply line (not shown) may be attached and a pressure gauge 22. The dished bottom 12 of chamber 10 contains an annular cushion member 24, of polyvinyl chloride or the like, forming a support for the bottom of an inserted grease cartridge 26 and is centrally apertured for connection of a dispensing fitting (not shown). 
     The grease cartridge 26 is shown in FIG. 2 as it is supplied for use. As shown the cartridge is composed of a relatively rigid cylindrical laminated paperboard body, suitably having a wall thickness of about 150&#34; a diameter on the order of 91/2&#34; and a length of about 181/8&#34;, so as to carry 38 pounds of grease, and preferably having an inner ply of aluminum foil so as to be resistant to grease. The bottom end of this body 26 has an end closure 28 crimped thereon in fixed transverse relation and carries a removable cap 30 therein to provide an exit port for grease as it is released through a dispensing fitting (not shown) attached at a central aperture 32 in the dished bottom 12 of chamber 10. The end closure 28 is also formed with annular ribbing 34 having a generally hat-shaped radial cross-section adjacent and inside the cartridge body 26 for reinforcing purposes and to provide for securely crimping it in place. 
     Additionally, the grease cartridge 26 includes a free piston 36 disposed in covering relation over the contained grease. This piston 36 is formed of a thin-walled, e.g. about 40 mils, plastic material such as polystyrene or other similar material that is impervious to grease. The piston 36 has an upstanding peripheral flange 38 thereon that is gently flared outwardly, e.g. at about 6° from vertical, with the upper flange edge having an outside diameter slightly larger than the inside diameter of the cartridge 26 so as to provide for airtight contact with the cartridge wall. Also, the piston 36 has its inner face formed at 40 in nesting relation with the end closure ribbing 34 for interfitting therewith so as to provide for completely exhausting grease from the cartridge 26 and for forming a &#34;drop center&#34; portion of the piston 36 as shown in FIG. 1 in the vicinity of the end of the leader from the numeral 36 for receiving substantially below the location of said air tight contact about half of the downward pressure exerted on the piston 36 by the aforementioned compressed air as indicated by the multiplicity of small arrows directed perpendicularly to the flat inside surface of the drop center in FIG. 1. The aforesaid nesting relation results in an annular peripheral portion of the piston disposed transversely of the cartridge 26, and a W-shaped radial cross-section of the piston adjacent its periphery as shown in the vicinity of the ends of the leaders from the numerals 36, 38 and 40 in FIG. 1, the drop center being connected to the annular portion by a generally annular upstanding wall. 
     In operation, a FIG. 2 cartridge is installed in the dispenser chamber 10 as shown in FIG. 1 and air pressure is applied through the fitting 20 commonly at about 15-50 pounds per sq. in. Under such air pressure the dispenser outlet fitting (not shown) is operated to release grease. The pressure within chamber 10 acts on piston 36 to force grease from cartridge 26. The pressure being exerted against the piston flange 38 maintains airtight contact with the wall of the cartridge despite any eccentricity or other deformity in cartridge 26. As the dispensing continues piston 36 ultimately reaches the bottom of cartridge 26 at an interfitted relation with end closure 28 so that all grease is expelled, and a fresh cartridge is then installed in chamber 10 to continue operations. 
     The present invention has been described in detail above for purposes of illustration only and is not intended to be limited by this description or otherwise to exclude any variation or equivalent means that would be apparent or reasonably suggested by the foregoing disclosure to the skill of the art.