Fluid dispenser with nested displacement members
A dispenser for dispensing liquids including an inner displacement member nested in an outer displacement member. The inner member is moveable between two end positions within the outer member by an actuator. The actuator is arranged to move the outer displacement member into a dispensing position when the inner displacement member is in one of its end positions. The displacement members can be pistons and/or bellows.
1. A dispenser comprising:
a chamber accommodating an inner displacement member nested within a bore disposed in an outer displacement member, the bore being in communication with the chamber,
the inner displacement member being moveable between a retracted position and a dispensing position within the bore of the outer displacement member by a shaft,
the shaft being coupled to the inner displacement member and the outer displacement member,
both the inner and outer displacement members being slidable within the chamber, the outer displacement member being slidable between a retracted position and a dispense position,
the shaft being arranged to move the outer displacement member into its dispensing position when the inner displacement member is in its dispensing position,
a first spring member biasing the inner displacement member towards its retracted position, and
a second spring member biasing the outer displacement member towards its retracted position.
2. The dispenser according to claim 1 wherein at least one of inner and outer displacement members is a piston.
3. A dispenser comprising:
an inner displacement member nested in an outer displacement member, the inner displacement member being moveable between two end positions within the outer displacement member by an actuator, the actuator being arranged to move the outer displacement member into a dispensing position when the inner displacement member is in one of its end positions,
wherein at least one of inner and outer displacement members is a piston, and
wherein the outer displacement member comprises a first piston movable within a piston chamber,
the inner displacement member comprises a second piston movable within a bore disposed in the first piston, the second piston movable between a retracted position and a dispensing position,
the bore being in open communication with the piston chamber,
the actuator comprising
a shaft fixed to the second piston,
a spring member biasing the second piston to the retracted position within the bore disposed in the first piston, and
wherein the shaft is provided with a seat for the spring member within the piston chamber and the second piston member is connected to the end of the shaft.
4. The dispenser according to claim 3 wherein the dispensing position of the first piston member is defined by an engagement member in the first piston chamber and wherein the distance between the retracted position and the dispensing position of the first piston member is less than a length of the shaft.
5. The dispenser according to claim 1 wherein the shaft is provided with a seat for the spring member within the chamber and the inner displacement member is connected to the end of the shaft.
6. The dispenser according to claim 4 wherein the shaft is provided with a seat for the spring member within the piston chamber and the second piston member is connected to the end of the shaft.
7. The dispenser according to claim 3 further comprising a second spring member that biases the first piston member to its retracted position.
8. The dispenser according to claim 1 wherein at least one of the inner and outer displacement members is a bellow.
9. The dispenser according to claim 2 wherein at least one of the inner and outer displacement members is a bellow.
10. The dispenser according to claim 1 wherein the dispensed volume per stroke by the inner displacement member ranges from about 1% to about 5% of a dispensed volume per stroke by the outer displacement member.
11. An apparatus for dispensing fluids comprising:
an inner displacement member nested in an outer displacement member, the inner displacement member being moveable between two end positions within the outer displacement member by an actuator, the actuator being arranged to move the outer displacement member into a dispensing position when the inner displacement member is in one of its end positions,
further comprising a plurality of canisters operatively connected to a dispenser, and
wherein the canisters and the corresponding dispensers are placed on a turntable comprising a driving means to rotate the turntable for positioning a selected dispenser in a position here it is operatively connected to a stationary operation module.
12. The dispenser according to claim 2 wherein the dispensed volume per stroke by the inner displacement member ranges from about 1% to about 5% of a dispensed volume per stroke by the outer displacement member.
13. An apparatus for dispensing fluids comprising:
an inner displacement member nested in an outer displacement member, the inner displacement member being moveable between two end positions within the outer displacement member by an actuator, the actuator being arranged to move the outer displacement member into a dispensing position when the inner displacement member is in one of its end positions,
wherein at least one of inner and outer displacement members is a piston, and
further comprising a plurality of canisters operatively connected to a dispenser, and
wherein the canisters and the corresponding dispensers are placed on a turntable comprising a driving means to rotate the turntable for positioning a selected dispenser in a position here it is operatively connected to a stationary operation module.
14. The dispenser according to claim 3 wherein the dispensed volume per stroke by the inner displacement member ranges from about 1% to about 5% of a dispensed volume per stroke by the outer displacement member.
15. An apparatus for dispensing fluids comprising:
an inner displacement member nested in an outer displacement member, the inner displacement member being moveable between two end positions within the outer displacement member by an actuator, the actuator being arranged to move the outer displacement member into a dispensing position when the inner displacement member is in one of its end positions,
wherein at least one of inner and outer displacement members is a piston,
wherein the outer displacement member comprises a first piston movable within a piston chamber,
the inner displacement member comprises a second piston movable within a bore disposed in the first piston, the second piston movable between a retracted position and a dispensing position,
the bore being in open communication with the piston chamber,
the actuator comprising
a shaft fixed to the second piston,
a spring member biasing the second piston to the retracted position within the bore disposed in the first piston,
further comprising a plurality of canisters operatively connected to a dispenser, and
wherein the canisters and the corresponding dispensers are placed on a turntable comprising a driving means to rotate the turntable for positioning a selected dispenser in a position here it is operatively connected to a stationary operation module.
16. The dispenser according to claim 4 wherein the dispensed volume per stroke by the inner displacement member ranges from about 1% to about 5% of a dispensed volume per stroke by the outer displacement member.
17. An apparatus for dispensing fluids comprising:
a plurality of canisters operatively connected to the dispenser according to claim 4 , and
wherein the canisters and the corresponding dispensers are placed on a turntable comprising driving means to rotate the turntable for positioning a selected dispenser in a position here it is operatively connected to a stationary operation module.