Fluid dispensing apparatus and method
A fluid dispenser including a body, a chamber coupled to or formed as part of the body and configured to contain a quantity of fluid, and a piston coupled to the body and rotatable within the chamber to different position. The piston is movable relative to the chamber in a first direction along an axis to draw fluid into the chamber, and the piston is movable relative to the chamber in a second direction opposite the first direction to discharge fluid from the chamber. The piston has stroke lengths that are selectable via the different rotational positions of the piston and that are associated with metered quantities of fluid to be drawn into the chamber. An anti-reversal feature is disposed between the piston and the body. The anti-reversal feature inhibits reversal of the piston during movement of the piston in the first direction or the second direction.
1. A fluid dispenser comprising:
a body;
a chamber coupled to or formed as part of the body and configured to contain a quantity of fluid;
a piston coupled to the body and rotatable within the chamber to different positions, the piston movable relative to the chamber in a first direction along an axis to draw fluid into the chamber, and the piston movable relative to the chamber in a second direction opposite the first direction to discharge fluid from the chamber, the piston having stroke lengths selectable via the different rotational positions of the piston and associated with metered quantities of fluid to be drawn into the chamber; and
an anti-reversal feature disposed between the piston and the body, the anti-reversal feature configured to inhibit reversal of the piston during movement of the piston in the first direction or the second direction.
2. The fluid dispenser of claim 1 , wherein the anti-reversal feature is defined by a ratchet mechanism including teeth disposed on the piston, and wherein the teeth are engageable by a portion of the body to inhibit reversal of the piston as the piston moves in the first direction or the second direction.
3. The fluid dispenser of claim 2 , wherein the portion of the body includes a pawl extending toward the piston and engageable with the teeth to inhibit reversal of the piston during movement of the piston.
4. The fluid dispenser of claim 3 , wherein the pawl is pivotally coupled to the body.
5. The fluid dispenser of claim 3 , wherein the pawl is resiliently deformable by movement of the piston.
6. The fluid dispenser of claim 3 , further comprising a support positioned on the body to bias the pawl to a neutral position to permit reversal of the piston on movement of the piston the entirety of the selected stroke length.
7. The fluid dispenser of claim 3 , wherein the piston has a toothless portion to permit reversal of the piston.
8. The fluid dispenser of claim 1 , wherein the anti-reversal feature is engageable with the piston in each of the first direction and the second direction to inhibit reversal of the piston.
9. The fluid dispenser of claim 1 , wherein the stroke lengths include a first stroke length and a second stroke length different from the first stroke length such that the piston is movable different distances in the first direction.
10. The fluid dispenser of claim 1 , wherein the piston is configured to rotate to each of the rotational positions without axial movement in the first direction or the second direction.
11. The fluid dispenser of claim 1 , wherein the piston is removable and replaceable relative to the body.
12. The fluid dispenser of claim 1 , wherein at least a portion of the piston is changeable to provide a stroke length associated with another metered quantity of fluid to be drawn into the chamber.
13. A fluid dispenser comprising:
a body;
a chamber coupled to or formed as part of the body and configured to contain a quantity of the fluid;
a piston coupled to the body and rotatable within the chamber to different positions, the piston movable relative to the chamber in a first direction along an axis to draw fluid into the chamber, and the piston movable relative to the chamber in a second direction opposite the first direction to discharge fluid from the chamber, the piston having different stroke lengths selectable via the different rotational positions of the piston and associated with different metered quantities of fluid to be drawn into the chamber; and
a mechanism disposed between the piston and the body and configured to control movement of the piston relative to the chamber, the mechanism having an anti-reversal state inhibiting reversal of the piston during movement of the piston in the first direction or the second direction along the selected stroke length, the mechanism further having a neutral state permitting reversal of the piston.
14. The fluid dispenser of claim 13 , wherein the mechanism is defined by a ratchet mechanism including teeth disposed on the piston, and wherein the teeth are engageable by a pawl in the anti-reversal state to prevent reversal of the piston during movement of the piston.
15. The fluid dispenser of claim 14 , further comprising a support positioned on the body, wherein the piston has a toothless portion, and wherein the support and the toothless portion adjust the ratchet mechanism to the neutral state.
16. The fluid dispenser of claim 13 , wherein the mechanism is in the neutral state on movement of the piston the entirety of the selected stroke length.
17. The fluid dispenser of claim 16 , wherein the piston is configured to rotate to each of the rotational positions without axial movement in the first direction or the second direction.
18. A method of dispensing a metered quantity of fluid from a fluid dispenser, the fluid dispenser including a body, a chamber, and a piston, the method comprising:
rotating the piston within the chamber to select a first rotational position of the piston from a plurality of rotational positions associated with different stroke lengths of the piston associated with different metered quantities of fluid to be drawn into the chamber, the piston movable in a first direction and a second direction along an axis in at least two of the plurality of rotational positions, and the first rotational position associated with a first stroke length to dispense a first metered quantity of fluid;
inhibiting reversal of the piston via an anti-reversal feature positioned between the piston and the body during movement of the piston along the first stroke length; and
permitting reversal of the piston for movement of the piston in the second direction via the anti-reversal feature on movement of the piston the entirety of the first stroke length.
19. The method of claim 18 , further comprising inhibiting reversal of the piston via the anti-reversal feature during movement of the piston in the second direction along the first stroke length.
20. The method of claim 18 , further comprising
rotating the piston within the chamber to select a second rotational position of the piston from the plurality of rotational positions, the second rotational position associated with a second stroke length different from the first stroke length;
inhibiting reversal of the piston via the anti-reversal feature during movement of the piston along the second stroke length; and
permitting reversal of the piston for movement of the piston in the second direction via the anti-reversal feature on movement of the piston the entirety of the second stroke length.