Dispenser

Abstract

A dispenser and related methods of dispensing material, in particular viscous materials, from a container and through a nozzle. The dispenser includes a body portion for holding the container in a fixed relationship with the body portion, a plunger movable to advance with respect to the container to urge material from the container through the nozzle, a motor arranged to move the plunger and a controller arranged to control the motor. The motor is controlled according to a distance traveled by the plunger, for example a dispensing distance or a distance the plunger is retracted away from the nozzle, or the motor is controlled according to a speed of the plunger.

Claims

1. A dispenser for dispensing a material from a container through a nozzle, the dispenser comprising: a body portion for holding the container in a fixed relationship with the body portion; a plunger moveable to advance with respect to the container to urge material from the container through the nozzle; a motor arranged to move the plunger; and a controller arranged to control the motor; wherein the controller is configured to calculate a back-EMF of the motor from a motor current, and use the back-EMF to calculate an actual motor speed, and configured to compare a desired motor speed and the actual motor speed and is arranged to act to minimize a difference between the desired motor speed and the actual motor speed and thereby to control the motor based on a speed at which the plunger moves, wherein the controller is further configured to determine a dosing amount of material to be dispensed from the dispenser and to control the motor such that the plunger is advanced a dispensing distance such that the dosing amount is dispensed, wherein the dispensing distance to be traveled by the plunger is determined as a stand-alone calculation for each dose of material dispensed.

2. The dispenser of claim 1, wherein the controller comprises an integrator configured to calculate the distance travelled by the plunger, wherein the integrator is reset prior to each dispensing stroke.

3. The dispenser of claim 1, further comprising a user input arrangement such that the dosing amount can be selected using a dial.

4. The dispenser of claim 1, wherein, the controller causes the motor to reverse once the plunger has travelled the dispensing distance such that the plunger is retracted from the nozzle.

5. The dispenser of claim 1, wherein the controller is further configured such that, once a desired amount of material has been dispensed, the motor is reversed to retract the plunger a distance away from the nozzle.

6. The dispenser according to claim 5, wherein control of the reversing of the motor is based on a distance travelled by the plunger.

7. The dispenser of claim 5, wherein the distance to be retracted by the plunger is determined as either a function of the distance advanced by the plunger to dispense the desired amount of material or a predetermined distance.

8. The dispenser of claim 1, wherein the controller is configured to determine the distance travelled by the plunger based on the actual motor speed of the motor.

9. The dispenser of claim 1, further comprising: a trigger arranged such that depressing the trigger causes rotation of the motor.

10. The dispenser of claim 9, wherein a degree to which the trigger is depressed directs a speed of rotation of the motor.

11. The dispenser of claim 1, wherein the body portion holds a plurality of containers and wherein the controller is arranged to dispense material such that a first material dispensed from a first container mixes with a second material dispensed from a second container.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) A specific embodiment is now described by way of example only and with reference to the accompanying drawing in which:

(2) FIG. 1 shows a schematic of a dispenser; and

(3) FIG. 2 shows a flow diagram illustrating the dispenser in use.

(4) While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE FIGURES

(5) With reference to FIG. 1, a dispenser 2 comprises a body having a stock portion 4 and a holder portion 6. The holder portion 6 comprises a cylindrical outer wall portion 8 defining a compartment in which a replaceable cartridge (not shown) may be housed, the cartridge containing a viscous material to be dispensed. The outer wall portion 8 is closed at a front end by a front cap 10 and closed at a rear end by a rear cap 12. The front cap 10 comprises a nozzle 14 through which the material may be dispensed.

(6) The stock portion 4 comprises an ergonomically shaped handle 16 accommodating a trigger 18 for controlling flow of the material from the nozzle 14, a dial 20 for selecting an amount of material to be dispensed, for example, a dosing amount, and a clutch arrangement 22, described in more detail below.

(7) The dispenser 2 further comprises a rack 24 having at a first end a plunger 26 arranged to abut an end of the cartridge, and at a second end a hook 28. The rack 24 comprises a series of teeth 30 along its length.

(8) The stock portion 4 further comprises a power supply 32 comprising a battery 34 for providing power to a motor 36 via a connection 38. The motor 36 is accommodated within the stock portion 4 and is a brush commutated DC motor.

(9) The stock portion 4 also accommodates a controller 40 for controlling the operation of the motor 36 via a connection 42. The controller 40 comprises an integrator (not shown) which calculates the distance traveled by the plunger, as will be described in more detail below. The dial 20 is coupled to the controller 40 via a connection 44, and the trigger 18 is coupled to the controller 40 by a connection 48. A potentiometer 46 is provided such that the trigger 18 may actuate the potentiometer 46, for example, via a mechanical link. The stock portion 4 further accommodates a gearing arrangement 50 coupled to the motor 36 via a connection 52 and comprising a gear 54 having teeth 56 arranged for engagement with the teeth 30 of the rack 24. The clutch arrangement 22 is coupled to the gearing arrangement 50 via a connection 58 and is arranged to engage and disengage the gear 54 and the motor 36.

(10) In use, the front cap 10 is removed, a cartridge containing a viscous material is inserted into the compartment defined by the cylindrical outer wall 8 of the dispenser 2, and the front cap 10 is secured back in place. To aid positioning of the cartridge in place, the clutch arrangement 22 is actuated such that the gear 54 and the motor 36 are disengaged, thereby enabling the position of the rack 24 to be adjusted such that the plunger 26 abuts an end of the cartridge. A user may use the hook 28 to aid adjustment the position of the rack 24. The clutch arrangement 22 may then be released such that the gear 54 and motor 36 are engaged.

(11) An amount of material to be dispensed may be selected by manipulation of the dial 20. The setting of the dial 20 is communicated to the controller 40 via the connection 44.

(12) Referring to FIG. 2, a control process for dispensing is now described. As indicated at reference numeral 60, the controller 40 determines a desired distance of travel of the plunger 26, or dispensing distance, based on the setting of the dial 20 in order to dispense a corresponding amount of material as set on the dial. For example, the dial 20 may comprise a scale of graduations indicative of a desired volume of material to be dispensed. When the dial 20 is set to a certain graduation, a desired distance of advance of the plunger 26 is determined corresponding to the desired volume of material to be dispensed as indicated on the dial 20. Determining the desired distance of advance of the plunger 26 takes account the cross sectional area of the cartridge such that the desired volume of material is dispensed, such that the product of the desired distance and the cross-sectional area of the cartridge (of all barrels of the cartridge if more than one) corresponds to the desired volume.

(13) Where the plunger 26 was retracted through a distance at the end of the previous stroke, the dispensing distance is determined based on the setting of the dial 20 and the distance retracted by the plunger 26 in the previous stroke. For example, the dispensing distance may be a sum of a distance determined by the setting of the dial 20 (as described above) and the distance retracted by the plunger 26 in a previous stroke. Accordingly, advance of the plunger 26 through the dispensing distance will correspond to the desired volume of material being dispensed, corrected to account for any retraction of the plunger 26 in the previous stroke.

(14) Once the dispensing distance has been set, the controller 40 monitors for signals received from the trigger 18 to determine when the trigger 18 has been depressed, as indicated at reference numeral 62.

(15) As described above, the controller 40 comprises an integrator configured to determine the distance traveled by the plunger. The integrator is reset to zero, indicated at reference numeral 64, before carrying out calculations to determine the distance traveled by the plunger such that the integrator provides a distance estimate relative to the last resting position of the plunger 26.

(16) On depression of the trigger 18, the controller 40 detects the degree to which the trigger 18 is depressed from the corresponding setting of the potentiometer 46. Based on this, the controller 40 determines a desired motor speed. The greater the degree to which the trigger 18 is depressed, the higher the desired speed of the motor 36. The controller 40 then directs the motor 36 to run, according to the desired motor speed, as indicated by reference numeral 66.

(17) When activated, rotation of the motor 36 is converted to rotation of the gear 54 via the gearing arrangement 50. By engagement of the teeth 56 of the gear 54 with the teeth 30 of the rack 24, rotation of the gear 54 causes linear motion of the rack 24. Accordingly, activation of the motor 36 results in linear motion of the rack 24, which causes the plunger 26 to be advanced and retracted towards and away from the nozzle 14, depending on the direction of rotation of the motor 36.

(18) When the plunger 26 is advanced towards the nozzle 14, the plunger 26 applies a force to one end of the cartridge, causing material to be forced from the cartridge through the nozzle 14.

(19) As the plunger 26 advances towards the nozzle 14, the distance traveled by the plunger 26 is monitored, as indicated by reference numeral 68. The monitored distance traveled by the plunger 26 is compared against the dispensing distance, as identified at reference numeral 70. If the distance traveled by the plunger 26 has reached the dispensing distance, advance of the plunger 26 is halted. If the distance traveled by the plunger 26 has not yet reached the dispensing distance, the controller 40 continues to monitor the distance traveled by the plunger 26 until the desired distance is reached.

(20) To monitor the distance traveled by the plunger, the controller 40 calculates the back EMF of the motor 36 from the motor current and from this calculates the motor speed of the motor 36. Alternatively, the back EMF of the motor 36 may be calculated or estimated by any other suitable means as will be understood by those skilled in the art. The calculated or estimated back EMF may be used to determine the motor speed since the motor creates a back EMF proportional to the speed of the motor. The distance traveled by the plunger 26 may then be determined based on the determined motor speed. For example, a calculation of motor speed results in a value which is stored as a variable. The position of the plunger 26 is determined by integrating this variable over a prescribed time period. In some embodiments where motor speed is determined in discrete digital samples, the distance traveled is determined by summing the speed samples and multiplying by a scaling factor.

(21) Once the distance traveled by the plunger 26 has reached the dispensing distance, corresponding to the desired amount of material to be dispensed, the controller 40 directs the motor 36 to stop or run in reverse (as will be described below), thereby halting the advance of the plunger 26.

(22) The controller 40 determines a retract distance, indicated at reference numeral 72, through which the plunger 26 is to be reversed. The retract distance is determined as a function of the distance advanced by the plunger 26 to dispense the desired amount of material or is a predetermined distance.

(23) Once the retract distance has been determined, the integrator is reset to zero before beginning to calculate the distance refracted by the plunger 26, as indicated at reference numeral 74. This provides a distance estimate relative to the last resting position of the plunger 26.

(24) The controller 40 directs the motor 36 to run in reverse, indicated by reference numeral 76, thereby retracting the plunger 26 from the cartridge. When the plunger 26 is refracted away from the nozzle 14, the force applied to the cartridge, and hence the force applied to the material, is removed and the material remains in the cartridge without oozing.

(25) As the plunger 26 retracts, the distance retracted by the plunger 26 is monitored, as indicated by reference numeral 78. The monitored distance retracted by the plunger 26 is compared against the retract distance, as indicated by reference numeral 80. If the distance traveled by the plunger 26 has reached the retract distance, movement of the plunger 26 is halted. If the distance traveled by the plunger 26 has not yet reached the retract distance, the controller 40 continues to monitor the distance traveled by the plunger 26 until the retract distance is reached.

(26) The distance through which the plunger 26 has refracted is determined based on the motor speed using a similar technique to that described above in relation to determining the distance advanced by the plunger 26.

(27) Once the distance traveled by the plunger 26 has reached the retract distance, the plunger 26 is halted by deactivation of the motor 36, indicated at reference numeral 82.

(28) To dispense a subsequent dose of material, the same process as outlined above is followed, only inserting a new cartridge when required. Since the integrator is reset at the start of each dispensing stroke, each dispensing distance is determined as a stand-alone calculation such that any errors which may occur in the calculation are not cumulative.

(29) Once all material in the cartridge has been dispensed, the cartridge may be removed from the dispenser 2. To do this, the clutch arrangement 22 is actuated such that the gear 54 and the motor 36 are disengaged, thereby enabling the position of the rack 24 to be adjusted to retract the plunger 26 away from the end of the cartridge. The user may use the hook 28 to aid adjustment the position of the rack 24. The cartridge may then be removed from the compartment defined by the cylindrical outer wall 8 of the dispenser 2.

(30) It will be understood that the order in which the acts outlined in FIG. 2 are carried out is by way of example only. It will be clear that operation of the dispenser is not limited to the order provided in FIG. 2. For example, the dispensing distance and retract distance may both be determined prior to dispensing beginning, or the motor may be stopped between being run in forward and then in reverse.

(31) In some embodiments, the dispenser does not comprise a clutch arrangement. In such embodiments the plunger 26 may be retracted from the cartridge by driving the motor 36 in reverse, thereby enabling the cartridge to be removed from the compartment defined by the cylindrical outer wall 8 of the dispenser 2.

(32) In some embodiments, the dispenser 2 is arranged such that the plunger 26 travels at a constant speed, such that material may be dispensed at a constant velocity. In use, to begin dispensing material, the trigger 18 is depressed. The degree to which the trigger 18 is depressed causes a corresponding setting of the potentiometer 46, which is detected by the controller 40. Based on the setting of the potentiometer 46, the controller 40 determines a desired motor speed. The greater the degree to which the trigger 18 is depressed, the higher the desired speed of the motor 36 and hence the higher the desired plunger speed. Alternatively, the desired motor speed, and hence desired plunger speed, may be a preset value.

(33) The controller 40 directs the motor 36 to run according to the desired motor speed.

(34) The controller 40 determines the actual motor speed using the techniques described above. Alternatively, the motor speed may be measured using any other suitable means. The controller 40 compares the actual motor speed with the desired motor speed. Where an error exists between the desired motor speed and the actual motor speed, the controller 40 adjusts the speed of the motor to minimise this error. Accordingly, the controller 40 acts as a control loop feedback mechanism, for example, a proportional-integral (PI) controller.

(35) It will be understood that the above description is of specific embodiments by way of example only and that many modifications, juxtapositions and alterations will be within the skilled person's reach and are intended to be covered by the scope of the appendent claims. For example, the dispenser may be arranged to dispense material from containers having a plurality of compartments, for example a multi-barrel cartridge comprising a plurality of barrels, e.g. two barrels.