Cartridge dispenser for liquid or semi-liquid materials

Abstract

A dispenser for a fluid material includes a handle portion and a cartridge having the material to be dispensed. The cartridge is easily mounted to the handle portion or removed, whereby the handle portion may be used with a variety of cartridges, each of which may contain a selected material. The handle portion includes a plunger that is moved linearly by actuation of a trigger mechanism, which is engaged by a user's finger. The trigger mechanism is configured to release pressure applied to the plunger quickly upon release of pressure on the trigger and to allow the plunger to move away from the cartridge to ensure release of pressure in the material to be dispensed to prevent dripping.

Claims

1. A dispenser for fluid materials comprising: a handle portion for removably receiving a cartridge containing said fluid materials, said handle comprising an annular slot configured to receive a flange on one end of said cartridge and support said cartridge in an orientation extending forwardly of said handle portion such that said cartridge can be rotated about a longitudinal axis of said cartridge, said annular slot being open at its top and unobstructed whereby said flange of said cartridge can be inserted into said slot without displacement of any structure, a plunger mounted for linear motion along said longitudinal axis of said cartridge, a trigger portion extending forward of said annular slot and carrying a trigger positioned to be engaged by a user at a location forward of said annular slot, and a trigger mechanism for advancing said plunger into said cartridge from said one end to expel said fluid materials, said trigger mechanism comprising said trigger positioned to be engaged and actuated by a user's finger and a gripper mechanism connected to said trigger to engage said plunger in response to application of force to said trigger by said user, wherein said gripper mechanism engages said plunger upon application of pressure to said trigger and disengages completely from said plunger to allow said plunger to move away from said cartridge upon release of pressure from said trigger, and further comprising a drag element consisting of a flexible disc received in an annular groove in said handle portion and slidingly engaging said plunger in a friction fit to prevent excessive movement of said plunger away from said cartridge upon release of pressure from said trigger.

2. A dispenser according to claim 1 wherein said plunger comprises a surface having a plurality of teeth spaced in the direction of said longitudinal axis to be engaged by said gripper when pressure is applied to said trigger.

3. A dispenser according to claim 1 wherein said plunger comprises a substantially continuous resilient surface to be engaged by said gripper when pressure is applied to said trigger.

4. A dispenser according to claim 1 wherein said annular slot has an angular extent of about 180 degrees.

5. A dispenser according to claim 1 wherein said trigger mechanism further comprises a pressure relief element.

6. A dispenser according to claim 5 wherein said pressure relief element comprises a spring.

7. A dispenser according to claim 1 wherein said trigger mechanism comprises a return spring attached between said gripper and a shell.

8. A dispenser according to claim 1 in further combination with said cartridge.

9. A dispenser according to claim 1 in further combination with a heater stand for heating said cartridge when attached to said handle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a perspective of a glue gun in accordance with the invention, with a glue cartridge in place.

(2) FIG. 2 is an exploded perspective of the glue gun of FIG. 1 showing the cartridge removed from the handle.

(3) FIG. 3 is partial vertical cross section of the handle portion of the glue gun of FIG. 1.

(4) FIGS. 3a and 3b are alternate cross sections taken along line 3a-3a of FIG. 3.

(5) FIG. 4 is an exploded view of the cartridge of the glue gun of FIG. 1.

(6) FIG. 5 is a perspective of the glue gun of FIG. 1 in a heater stand in accordance with the invention.

(7) FIG. 6a is a side view of a heater element used in the heater stand of FIG. 5.

(8) FIG. 6b is a front view of the heater element of FIG. 6a.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(9) With reference to FIG. 1, the dispenser of the invention comprises a handle portion 2 and a cartridge portion 4. The handle portion is formed by a shell 3, which may be molded plastic, and includes a plunger 6 slidingly mounted in the shell for movement, and which the user controls by trigger 8. With reference to FIG. 2, it will be appreciated that in the preferred embodiment, the cartridge includes a flange, or lip, 10 at one end and that this flange is configured to engage a slot 12 in a first portion of the handle when the cartridge is in an operative position on the handle as shown in FIG. 1. Handle 2 also includes a trigger portion 14 that extends forward of the first portion to support the trigger 8. It will be appreciated that this construction provides easy installation or removal of the cartridge to facilitate use of a variety of adhesive compositions during a single project. In addition, the preferred construction described allows the cartridge to rotate about its longitudinal axis, which allows the user to orient the dispensing nozzle to a desired orientation when a non-symmetric nozzle is used. The slot and flange preferably fully support the cartridge so that it does not contact the handle portion at other locations to prevent transfer of heat for a heated cartridge to the handle portion.

(10) FIG. 3 illustrates the preferred mechanism for advancing the plunger 6. While any of several similar mechanisms may be used, the mechanism illustrated is similar to that shown in U.S. Pat. No. 4,523,705. The illustrated mechanism includes the trigger 8, which engages a lever 16 that is pivotally mounted to the housing at 17. The upper part of the lever is connected by a link 18 to a pivoting gripper 20. The gripper is pivotally mounted to a housing 22 through which the plunger 6 passes. The housing 22 is mounted for linear motion in the shell 3, as by sliding in cooperating tracks, and a return spring 23 is connected between the shell 3 and the gripper to release the gripper from the plunger 6 when pressure is removed from the trigger. When the user pulls the trigger, lever 16 rotates about mount 17, and movement of the link 18 in turn rotates the gripper 20. When rotated, the gripper engages the bottom of the plunger, and the housing then moves forward to advance the plunger. In the preferred embodiment shown, the return spring 23 connected between the link 18 and the handle controls the rotation of the gripper and motion of the housing as is explained in the '705 patent. The return spring 23 causes the gripper to pivot downward immediately upon the user's releasing pressure on the trigger. The spring also pulls the housing rearward so that it will be in a position to engage the plunger again at a location whereby it can advance the plunger upon application of pressure to the trigger.

(11) An important feature of the above construction is that the plunger is immediately disengaged from the advancing mechanism upon release of pressure on the trigger. This, in turn immediately releases the pressure in the cartridge that is caused by the plunger. This contrasts with those structures that do not immediately release the plunger and, thus, often drip undesirably.

(12) The shell 3 further supports a drag element 25 that engages the plunger to prevent excessive rearward movement of the plunger when pressure on the trigger is released. This element may be a disc that fits in a groove in the shell 13 and has a central hole for allowing frictional passage of the plunger.

(13) The trigger further includes a pressure relief spring 27 that prevents application of excessive pressure to the dispenser mechanisms.

(14) FIG. 4 illustrates the preferred construction of the cartridge 4. The cartridge is generally tubular for receiving the fluid material. An outlet 24 is located at a dispensing end of the cartridge and is configured to receive a selected dispensing tip 26, which may take any of several forms as illustrated depending on the particular project. For example, the tips may be broad to lay down a ribbon of material or may be cylindrical of various diameters. As noted, the tip may be oriented by rotating the cartridge.

(15) Preferably, the cartridge is that described in published PCT application WO 2004/017205, which includes a valve 28 disposed in the front of the cartridge. This valve efficiently controls the discharge of the adhesive, and an important feature of the invention is the combination of the valve 28 and the feed mechanism. When pressure on the trigger is removed, the gripping mechanism immediately releases the plunger, which releases the pressure on the adhesive in the cartridge. The valve 28 is designed to close quickly in response to the reduced pressure and also has been found to operate as a diaphragm that draws material into the cartridge when pressure is released and the valve recovers is original configuration. The rapid release of pressure allows the drawback to take place and greatly reduces dripping.

(16) The plunger is preferably configured with a lower surface that cooperates with the gripper mechanism to provide fine control of the plunger. In one embodiment, the lower surface of the plunger is provided with teeth 19 (see FIG. 3a) that are engaged by the upper edge of the gripper when it pivots upward. The pitch of these teeth may be very small to provide accurate control. For example, a pitch of about 0.030 inch has been found useful. In another embodiment, the lower surface of the plunger is provided with a continuous layer 21 (see FIG. 3b) of urethane or a hard, rubber-like compound or other material that provides a good grip to the gripper, much as a glue stick, but that recovers its original shape and can be used repeatedly. The use of a continuous layer provides a micro-fine advancement of the plunger and is particularly useful when the desired pitch of the teeth is too small for practical manufacture.

(17) FIG. 5 illustrates another feature of the invention. A heater stand 30 is provided to receive the cartridge and to heat the adhesive in the cartridge. The stand includes a base part 32, which is designed to rest on a horizontal surface. An upper part 34 includes a cylindrical part for engaging the cartridge. Thus, the forward portion of the upper part 34 receives the forwardly extending part of the cartridge and engages the forward edge of the trigger portion of the handle, while the rear portion of the upper part extends rearward to cover the rear part of the cartridge.

(18) FIG. 6a is a side view of a heater casing 36 that is received in the heater stand shown in FIG. 5. The heater casing 36 is shaped to receive the cartridge and to also receive a heater element (not shown) in cavity 38. FIG. 6b is a rear view of the heater casing.

(19) The heater is useful for those situations where the fluid material is to be kept warm during periods of non-use. The fluid materials in the cartridge may be of the type that become liquid or semi-liquid only when heated, and the heater stand may be used when such materials are used. The cartridge may be heated initially in the heater stand, but it is preferably heated in a separate heater where, for example, a plurality of cartridges may be heated initially. The heated stand, thus, preferably maintains the temperature of the fluid materials when the rate of usage is low enough that they might cool.

(20) It will be appreciated that a unique dispenser has been disclosed. Modifications will be apparent to those of skill in the art.