Dispenser for viscous material and controller therefor

Abstract

 A pneumatic controller for a dispenser for viscous materials has a pistol grip body (50) in which is mounted a trigger (52) which is operably connected with regulated pressure setting member (16) of a pressure regulator (10) by a pair of linkages (56 and 60) pivotally connected to the trigger and the body. As the trigger is depressed the plunger adjusts the regulated pressure setting. This allows the rate at which the viscous material is dispensed to be adjusted by the hand holding the pistol grip.

Description

[0001] The present invention relates to pneumatically actuated dispensers for viscous material and to a controller thereforcomprising a body, a trigger, and a pressure regulator having an inlet for supply air and an outlet.

[0002] In the specification a pneumatically actuated dispenser for viscous material comprises an actuating piston and cylinder device, a plunger connected to the piston of the device and a keep for a cartridge containing the material.

[0003] EP-A-0369568 describes a pneumatically actuated dispenser for viscous material which has a handle mounted trigger for opening and closing a pneumatic flow path from an air supply to a regulator associated with the actuating piston and cylinder device of the dispenser. The regulator includes an adjuster for setting the pressure in the cylinder. The trigger is arranged to admit or prevent the supply air to the cylinder at a pressure set by the regulator.

[0004] Practically, it is difficult to control the flow rate of material discharged from the dispenser with the trigger. To adjust the actuating air pressure, and hence the flow rate of discharge material, it is necessary to reset the adjuster. This is difficult to do while material is being discharged, as the trigger has to be first depressed with one hand while adjustment is made with the other. The other approach is to discontinue discharging the material, set the desired pressure and start again.

[0005] The present invention aims to alleviate these problems.

[0006] The present invention is characterised by a movable regulated pressure setting member arranged to be responsive to movement of the trigger, to change the regulated pressure at the outlet of the regulator.

[0007] Preferably, the body comprises a handle which is formed as a pistol grip, comprising a portion to be held in the palm of the hand of a user, the trigger being engageable by a finger or thumb of the said hand. The trigger may be pivotably connected to the handle or arranged for linear movement to move the pressure setting member of the regulator. The trigger could be in the form of a lever, a linearly slidable member or other means by which force can be applied to regulated pressure setting member, such as a button.

[0008] Preferably, the regulator is mounted (or at least partially mounted) within the body of the handle.

[0009] The connection between the trigger and the pressure setting member may be by means of a mechanical linkage. For example, a pair of linkage arms may be connected, at their respective first ends, to the trigger and a point on the handle, the second ends of the arms are pivotably connected together to rotate relative to one another as the trigger is moved to change the position of their common pivot relative to the handle, the pressure setting member being arranged to engage one of the arms intermediate its ends to move in response to movement of the trigger. Preferably, the engagement of the pressure setting member by one of the arms is towards the common pivot between the arms.

[0010] Preferably, the trigger is biased to a position corresponding to a predetermined regulated pressure setting of the regulator. The bias may act directly upon the trigger and/or be a constituent part of the regulator the latter biassing the trigger through the pressure setting member. Desirably, the mechanical advantage of the means of application of the force applied to pressure setting member increases with the degree of movement of the trigger.

[0011] The regulator may be arranged to regulate the outlet pressure to be substantially constant for a given position of the trigger, the outlet pressure being variable in response to movement of the trigger.

[0012] Preferably, the pressure setting member is a linearly slidable plunger.

[0013] In a preferred embodiment, the pressure setting member comprises a plunger having a first portion which is coupled, through a resilient intermediate member, to a regulating piston of the regulator. The pressure setting member may have a second portion which extends from a housing of the regulator and is arranged for pressure setting movement in response to movement of the trigger. The pressure setting member may be provided with an abutment, such as a flange, in order to provide a limit to its movement in one direction. The flange may prevent the pressure setting member from detaching from the regulator housing.

[0014] The outlet pressure may be governed as a function of the position of the pressure setting member such as being linearly dependent upon the position of the pressure setting member. Preferably, the outlet pressure is related to the degree of depression of the trigger.

[0015] A controller according to the invention allows variation of the regulated outlet pressure simply by movement of the trigger. The minimum pressure may be determined by the flange on the pressure setting member engaging an abutment on the regulator housing, limiting the extent of its movement in one direction. Alternatively the minimum pressure could be determined by a flange on the trigger engaging an abutment on the controller body to limit its extent of movement in one direction. The maximum value may be limited by an adjustable stop mounted on the body, to limit the extent of movement of the trigger in the other direction.

[0016] The stop may be associated with or separate from locking means for locking the trigger in a position intermediate those corresponding to the minimum and maximum regulated outlet pressure settings.

[0017] In one embodiment, the control constitutes a stock of a dispensing gun for viscous material, the stock being provided with means for connecting it to the body of the gun.

[0018] The outlet of the regulator may be connected to the inlet of an actuating piston and cylinder device of a dispenser which is arranged to advance a dispenser plunger to discharge the viscous material from a cartridge.

[0019] The stock may be formed with a saddle which enables it to be connected to dispensers of various sizes. The saddle may be of flexible material to accommodate dispenser cylinders of various sizes. The stock may include couplings for attaching the controller outlet to the cylinder of the dispenser and the controller inlet to a pneumatic supply line.

[0020] In some embodiments, the controller may include a pneumatic switch for directing air to alternate inlets on either end of side of an actuating piston in an actuating cylinder. In this way, actuation of the switch could select the direction in which the actuating piston is urged.

[0021] According to a second aspect of the present invention, there is provided a dispenser for viscous material of the type specified, including a controller according to the invention.

[0022] Preferably, the dispenser includes a dump valve connected between the controller and the pressure cylinder. The valve is arranged to vent air if pressure on the controller side of the valve drops substantially below that on the cylinder side of the valve.

[0023] The present invention may be carried out in various ways, some examples of which will now be described with reference to the accompanying drawings, in which :

Fig.1 is a partial cross section of a regulator for a controller according to the present invention;

Fig.2 shows schematically a controller according to the present invention incorporating the regulator of Fig.1;

Fig.3 shows a portion of the controller of Fig.2;

Fig.4 shows a modification of the controller in Fig.2;

Fig.5 shows schematically how the controller of Fig.2 may be connected to dispensers of various sizes; and

Fig.6 is a side section of the rear end of the dispenser of Fig.4.

[0024] Referring to Figs. 1 and 2, an air pressure regulator 10 has an inlet 12, an outlet 14 and a pressure setting plunger 16.

[0025] The plunger 16 comprises a flange 18 at one end which is a sliding fit within a bore 20, defined by a body 22 of the regulator 10, and a narrower stem portion 24 which projects out of the bore 20 past a radially inwardly projecting retaining collar 26 in one end of the bore 20.

[0026] This arrangement allows the plunger 16 to slide within the bore 20, the extent of its movement out from the bore 20 being limited by the engagement of the flange 18 with the collar 26. In other embodiments, the separate collar 26 could otherwise be integral with the body 22 of the regulator 10.

[0027] A helical spring 28 biases a piston 30 riding in the bore 20 away from the flange 18. The piston 30 has a peripheral annular recess 32 which holds an O-ring seal 34 which seats against the bore 20.

[0028] The piston 30 also includes a co-axial vent port 36. The piston 30 is formed into a stem 38 through which the port 36 extends on the side opposite that on which the spring 28 is located. The end of the stem 38 acts as a valve seat 40 which is arranged to engage a regulating seal plate 42 biased towards the stem 38 by a helical spring 44 mounted in the bore 20 adjacent its connection with the inlet 12.

[0029] The body 22 has a radially inwardly projecting annular 'knife-edge' seat 46 which limits the extent of movement of the regulating seal plate 42. When engaged, the seat 46 and seal plate 42 seal the inlet 12 from the remainder of the bore 20. A passage 48 leads away from the bore 20 to the outlet 14 in the form of a flexible tube.

[0030] When a pneumatic supply is coupled to the inlet 12 the regulator 10 governs the pressure at the outlet 14 as follows :

[0031] When the plunger 16 is depressed, the spring 28 compresses and exerts an increased force on the piston 30. The valve seat 40 pushes the regulating seal plate 42 away from the seat 46. Air then flows from the supply through the inlet 12 to the outlet 14 and the pressure at the outlet 14 rises. When the force exerted as a result of pressure acting on the piston 30 sealed by the seal plate 42 exceeds the force applied to the piston 30 by the spring 28, the piston 30 allows the seal plate 42 to return towards the seat 46. When the pressure is sufficient, the seal plate 42 will reseat, stopping air flowing from the inlet 12. Unless the pressure at the outlet 14 drops or the plunger 16 is moved again, the regulator 10 is in balance.

[0032] If at this point the plunger 16 is released to project further from the bore 20, the pressure at the outlet 14 multiplied by the area of the bore 20 exceeds the force exerted by the spring 28 on the piston 30 and the piston 30 will move in the bore 20 towards the plunger 16 so that the seal of the valve seat 40 against the seal plate 42 is broken, allowing the excess pressure to be reduced by air escaping through the vent port 36 past the plunger 16 to atmosphere until the system balances again.

[0033] The insert 26 may be removed to permit withdrawal of the plunger 16 and spring 28 and, if desired, the spring 28 may be replaced by another of a different rating for an application requiring a different maximum outlet pressure.

[0034] The springs 28, 44 need not comprise helical springs and could instead comprise other forms of compressible or resilient means providing similar biassing for the plunger 16 and the piston 30, and the seal plate 42 and seat 46, respectively.

[0035] Fig.2 shows the regulator 10 installed within a pistol grip type handle 48 of a controller 50.

[0036] A trigger 52 is pivotably mounted on the handle 48 by a pivot pin 54. A first linkage arm 56 is pivotably connected to the trigger 52 by a pivot pin 58 spaced from the pivot pin 54. The other end of the first linkage arm 56 is pivotably connected to a second linkage arm 60 which is pivotably coupled at its other end to a further pivot pin 62 inside the handle 48. Alternatively, the pair of linkage arms could be replaced by a unitary flexible arm having a region of flexure replacing the pivotable connection between the linkage arms.

[0037] The linkage arms 56,60 flex relative to one another as the trigger 52 is squeezed or released to cause the pressure setting plunger 16 in the regulator 10 to be depressed or extended. The mechanism formed by the linkage arms 56,60 and the trigger 52 is such that the mechanical advantage of the trigger 52 and the plunger 16 increases as the trigger 52 is depressed. The trigger 52 may therefore be compensated to give a 'constant feel' as it is depressed, i.e. the increasing force of the spring 28 beneath the plunger 16 is countered by the increasing mechanical advantage assisting the force applied to the trigger 52.

[0038] Attached to the pivot 58 is a strut 64 which has an axial bore 66, containing a spring 68 and a spigot 70 which extends into a recess 72 in a movement limit stop 74. Both of the strut 64 and the limit stop 74 have helical engagement surfaces 76 as shown in Fig.3. The limit stop 74 may be rotated by a knob 77 on the exterior of the handle 48 for varying the maximum amount by which the trigger 52 may be depressed. The sprung spigot 70 biasses the trigger 52 outwards towards the minimum regulated outlet pressure setting so that, when the trigger 52 is released, the minimum outlet pressure setting is selected. By adjusting the variable stop 74, the trigger movement can be adjusted for the maximum required pressure or material flow rate. Of course, the knob could be mounted in the trigger with the limit stop so that it cooperates with the strut mounted on the handle.

[0039] Figure 4 shows a modified controller 50 which includes a selector switch 78. The switch 78 selects between different outlets (not shown) leading to opposite sides of a piston 104 in a dispenser actuating cylinder 90 so that the piston may drive a dispensing plunger 105 either way as required.

[0040] Figure 5 shows an embodiment in which the pistol grip handle 48 includes a saddle 80 which is of flexible material for attaching the handle to pressure cylinders 82,84,86 of dispensing guns with differently sized actuating cylinders.

[0041] A fastening belt or collar 88 of sprung steel or a suitable plastics material is employed for attaching a selected dispenser actuating cylinder 82,84,86 to the handle 48.

[0042] Figure 6 shows a partial view of the rear of the actuating cylinder 90 of the embodiment of Figure 4 in which a flexible pipe 92 leads from the regulator 10 to a pressure vent 94. The vent includes a dump valve 96 containing a flexible disc 98. When the trigger 52 is squeezed to force compressed air up the pipe 92, the disc 98 moves to the left as seen in Figure 6. The compressed air can travel around the edges of the disc through notches 100 in the vent body 102 so that pressure is applied to the piston 104 of the cylinder 90. If the trigger 52 is released rapidly, the regulator 10 vents air to atmosphere and the pressure in the pipe 92 may drop below that in the cylinder 90. The disc 98 may therefore move to the right as seen in Figure 6, opening large outlet ports (not shown) in an end wall 106 which allows rapid exhaust to atmosphere.

[0043] A replacable material cartridge 108 is attached to the cylinder 90 at a coupling keep 110. The cartridge has an aperture 112 at one end for dispensing material as the trigger 52 is squeezed.

[0044] A dispenser incorporating a controller according to the invention allows a variable material discharge rate simply by the amount the trigger 52 is depressed. The operator is able to start application slowly and to build up speed as necessary and to release the trigger 52 to slow the flow rate. The discharge of viscous material can be brought to a controlled stop with little or no seepage when the trigger 52 is fully released.

Claims

1. A controller (50) for a pneumatically actuated dispenser of viscous material, the controller comprising a body (48), a trigger (52), and a pressure regulator (10) having an inlet (12) for supply air and an outlet (14), characterised by a movable regulated pressure setting member (16) arranged to be responsive to movement of the trigger to change the regulated pressure at the outlet of said regulator.

2. A controller as claimed in claim 1 in which the body comprises a handle (48) formed as a pistol grip in which is mounted the trigger.

3. A controller as claimed in claim 1 or 2 in which the trigger is arranged for rotational or linear movement in relation to the body linearly to move said pressure setting member of the regulator.

4. A controller as claimed in any of claims 1 to 3 in which the regulator is mounted at least partially within the body.

5. A controller as claimed in any preceding claim in which the trigger is operably connected with the pressure setting member by means of a mechanical linkage (56, 60).

6. A controller as claimed in claim 5 in which the linkage comprises an arm (56, 60) connected, toward its ends, to the trigger and a point on the body, respectively, the arm being flexible intermediate its ends to as the trigger is moved to change the position of its region of flexure relative to the body, the pressure setting member being arranged to engage the arm, intermediate its ends, at or near the region of flexure, to move in response to movement of the trigger.

7. A controller as claimed in any preceding claim in which biassing means (28) bias the pressure setting member to a preset minimum pressure setting of the regulator.

8. A controller as claimed in any preceding claim in which the pressure setting member is a linearly movable member (16) and the pressure regulator has a regulating valve body (42) and cooperating regulating valve seat (40), which valve body and seat are each biassed by biassing means (28,44) to a closed position against the force exerted by the pressure of the supply air, the member being arranged to be movable against the biassing means to vary the biassing force exerted thereby as the trigger is moved.

9. A controller as claimed in any preceding claim, including adjustable maximum pressure limiting means arranged to limit the movement of the pressure setting member in response to movement of the trigger.

10. A controller as claimed in claim 9 in which the adjustable pressure limiting means are a rotatable rod (64) and an abutment (74) one of which is movable with the trigger, each of which has an engageable surface which is undulating about the axis of rotation of the rod, such that the end surfaces of the rod and the abutment engage to determine the extent of travel of the trigger according to the orientation of the rod relative to the abutment about the axis of rotation.

11. A controller as claimed in any preceding claim including a pneumatic switch (78) arranged to direct air from the outlet of the pressure regulator along either one of two outlet paths.

12. A dispenser for viscous material comprising an actuating piston and cylinder device, a dispensing plunger (105) connected with the piston (104) of the device, a keep (110) for a cartridge (108) containing the material and a controller (50) as claimed in any preceding claim, the outlet path or paths from the regulator being operably connected to actuate the piston of the piston and cylinder device.

Drawing