LIQUID METERING DEVICE

Abstract: A metering device comprising a body (11) supporting and enclosing a bladder (13) which has an inlet and an outlet each controlled by a non-return valve (19 and 21), the body (11) is formed with an opening (22) and supports an operator (23) which is movable relative to the body (11), the operator has a portion (24) which moves into and out of the body (11) through the opening (22) to engage and vary the volume of the bladder (13), said operator being associated with a cam member (25) which is engageable by the operator (23) to limit the return stroke of the operator, the cam member being adjustable to vary the stroke of the operator. The device is particularly applicable to drench guns and the like.

Description: LIQUID METERING DEVICE THIS INVENTION relates to a metering means and particularly a metering means intended for the metering of active ingredients such as pharmaceuticals, veterinary substances, pesticides, weedicides and like compositions. In one form the invention resides in a metering device comprising a body supporting and enclosing a bladder said bladder having an inlet and an outlet each controlled by a non-return valve, said body being formed with an opening and supporting an operator which is movable relative to said body whereby on movement of the operator with respect to the body a portion of the operator moves into or out of the body through the opening to engage and vary the volume within the bladder, said operator being associated with a movable cam member having a camming surface which is engagable with the operator to control its degree of entry into the body said camming surface to vary the degree of movement of the operator relative to the body on movement of the cam member. The invention will be more fully understood in the light of the following description of several specific embodiments. The description is made with reference to the accompanying drawings of which: Figure 1 is a schematic sectional elevation of the first embodiment in the "maximum dose" situation; Figure 2 is a schematic sectional elevation of the embodiment in the "minimum dose" situation; Figure 3 is an end elevation of the embodiment; Figure 4 shows an alternative mounting for the cam member; Figure 5 is a part elevation of a second embodiment; and Figure 6 is a part sectional elevation of a third embodimen . The first embodiment is directed towards a metering device for use in assocation with a drenching gun and comprises a substantially tubular body 11 which is closed at either end by end caps 12. The tubular body 11 accommodates within itself a tubular flexible bladder 13 which is closed at either end by end plugs 14 and 15 which clampingly engage the respective ends of the bladder against the adjacent ends of the tubular body 13. Each of the end plugs 14 and 15 are formed with an axial passageway 16 and 17 respectively. One end plug 14 is also received and supported by one of the end caps 12 to extend beyond the end cap and supports an outlet nozzle 18 which may be adapted at its outer end to accommodate an extension member and which supports within itself a non¬ return valve 19 to ensure that there can only be a flow of fluid from within the bladder 13 out through the outlet nozzle 18. The axial passageway 17 in the other end plug 15 is formed by a tubular member 20 which extends through the end plug 15 and protrudes beyond the end cap 12. The outermost end of the tubular member 20 is adapted for connection to a fluid line for the active agent to be metered by the metering device. The inner face of the end plug 15 supports a non-return valve 21 which is associated with the tubular member 20 to ensure that there is only a flow of fluid from the tubular member 17 to the bladder 13. ' The body 13 is formed with an opening 22 which extends axially along almost the full length of the body and is associated with an operator in the form of a lever 23 which is pivotally mounted to the body to be pivotable about a pivot axis 28 towards and away from the body over said opening 22. The lever 23 is associated with an extension piece 24 the length and width of which corresponds substantially with the length and width of the opening 22. On pivotal movement of the lever 23 towards the body 13, the extension piece 24 enters the opening 22 in the body to engage the bladder and cause the collapse thereof. The lever 23 is associated with an annular cam member 25 supported at the inlet end of the body 13 to be rotatable over the respective end cap 12b and tubular member 20. The cam member 25 is associated with a locking nut 26 which is threadably engaged over the tubular member 20 to provide for clamping engagement of the cam member 25 between the locking nut 26 and end cap 12. The cam member has an annular configuration and is formed at its outer edge with an axially directed flange 27 extending the full circumference of the cam member 25. The flange 27 is of variable thickness. The lever 23 is formed with an extension 29 which extends to the rear of the pivot axis 28 and is engagable with the outer surface of the flange 27 of the cam member 25. As shown at Figure 3 the flange 27 is formed with a radial protrusion 30 adjacent the portion of the flange having greatest thickness which provides a thumb or finger grip 31 to facilitate rotation of the cam member 25. The bladder 13 is formed of a resilient material and has a normal configuration conforming substantially to that of the internal configuration of the tubular body 11. As a result the lever 23 is biassed to its outer most position in relation to the opening to a degree which is controlled by the engagement of the rearward extension 29 of the lever 23 with the flange 27 of the cam member 25. On selective rotation of the cam member 25 the potential degree of entry the extension piece 24 of the handle 23 into the body 13 will vary. As a result the available degree of movement of the lever 23 towards the body 13 is also variable and consequently the degree of volume displacement effected on the bladder by such movement is variable. The cam member 25 is calibrated according to the degree of volume displacement effected by movement of the lever 23 towards the body 13 for each position of the cam member around the end of the body 13. Figure 1 illustrates a "maximum dose" arrangement whereby the thickness of the portion of the flange 27 engaged by the rearward extension 29 of the lever 23 is at its minimum and as a result the degree of movement available to the lever with respect to the handle 13 is at its maximum. Consequently the volume displacement effected on the bladder by such movement is also at its maximum. When the metering device is at its "miminum dose" situation as shown at figure 2 whereby the portion of the flange 27 of the cam member 25 engaged by the rearward extension 29 of the lever 23 has its greatest thickness, the available degree of movement of the handle 23 towards the body 13 is at its minimum. Consequently the resultant volume displacement which may be effected by such movement is also at its minimum. The function of the locking nut 26 serves to ensure that the camming surface is maintained at a desired dosage position for the desired period. In event that it is required to vary the dosage the locking nut is adjusted to remove the clamping engagement with the cam member 25 and allow rotation of the cam member 25 to the desired dosage position. An alternative mounting arrangement for the cam member 25 of the first embodiment is shown at Figure 4. According to the alternative mounting the cam member 25 is formed as eccentric annulus which is slidably received in a circumferential groove in the end cap 12 to be capable of rotation about the central axis of the end cap 12 and tubular body (not shown). The outer surface of the annular is eccentric to provide a camming surface of similar form to that of the first embodiment. A second embodiment of the invention varies from the first embodiment in the nature of the inter-engagement between the lever 23 and the cam member 25 as shown at Figure 5. The cam member 25 . of the second embodiment comprises an annular element having a conical outer surface and a threaded inner bore. The cam member is threadably engaged on a threaded formation 32 provided on the exterior of the end cap 12 which is itself threadably engaged with the end of the tubular body 11. The conical outer surface of the cam member 25 is located adjacent the rearward extension 29 of the lever 23. On rotation of the cam member 25 on the tubular body 11 and end cap 12 the cam member is displaced axially along the tubular body to vary the degree .of movement which is available for the lever 23. The axial position of the cam member on the tubular body may be calibrated according to the displacement volume effected by the lever at various positions of the cam member. The third embodiment as shown at Figure 6 also varies from the first embodiment in the nature of the inter-engagement between the lever 23 and the cam member 25. The cam member 25 is provided by the exterior surface of the end cap 12 which has a frusto-conical configuration. The rearward extension 27 of the lever 23 slidably supports a threaded stud 33 the outer end of which is adapted to bear on the cam member 25. The rear extension also rotatably supports an annular nut 34 which threadably engages the stud 33 whereby rotation of the nut 34 in the rearward extension will vary the axial displacement of the stud from the end of the rearward extension. Calibrations may be provided on the stud to indicate the available volume displacement for a variety of positions of the stud 33 within the rearward extension 27. As a result of each of the embodiments a metering device is provided which may be readily calibrated and provide readily recognisable indication of the dosage effected by operation of the device. It should be appreciated that the scope of the present invention need not be limited to the particular scope of the embodiment described above or the particular application of the invention of the embodiment.

Claims: THE CLAIMS defining the invention are as follows:- 1. A metering device comprising a body supporting and enclosing a bladder said bladder having an inlet and an outlet each controlled by a non-return valve, said body being formed with an opening and supporting an operator which is movable relative to said body whereby on movement of the operator with respect to the body a portion of the operator moves into or out of the body through the opening to engage and vary the volume within the bladder, said operator being associated with a cam member which is engagable with the operator to control its degree of entry into the body adjustment means provided between the operator and cam member to vary the available degree of movement of the operator relative to the body. 2. A metering device as claimed at claim 1 wherein said body is tubular and said opening extends axially along the wall of the body, said portion having a cross-sectional configuration substantially complementary to the configuration of the opening. 3. A metering device as claimed at claim 1 or 2 wherein said operator comprises a lever pivotally mounted to the body. 4. A metering device as claimed at claim 2 or 3 wherein said cam member is rotatably mounted to the body for rotation about the central axis thereof. 5. A metering device as claimed at claim 4 wherein the camming surface comprises an eccentric configuration on the outer periphery of the cam member. 6. A metering device as claimed at claim 4 wherein the cam member is movable axially along the body on rotation about the central axis thereof. 7. A metering device as claimed at claim 3 wherein the lever is provided with means for engaging the cam member which is associated with the adjustment means to be displacable to vary the available degree of movement of the operation relative to the body. 8. A metering device as claimed at claim 7 wherein the adjustment means comprises a threaded stud threadably engaged by a nut rotatably supported by the lever. 9. A metering device substantially as herein described with reference to the accompanying drawings. 10. A drench gun incorporating a metering device as claimed at any one of claims 1 to 6.

Inventors: HARRIS GRAEME WILLIAM, HARRIS, GRAEME, WILLIAM
Applicants: HARRIS GRAEME WILLIAM, HARRIS, GRAEME, WILLIAM
Application year: 1986
Main classification: F04B13
IPC codes: A61D7, F04B9, F04B43, G01F11