Peristaltic metering pump and methods of operation
A peristaltic pump is provided for conveying a fluid pumping medium through a compressible hose. The pump is designed particularly for use in an aquarium, terrarium, or vivarium for metering fluids accurately and reliably by eliminating permanent tubing deformation and random stopping positions of rollers.
1 . A peristaltic metering pump for aquariums, vivariums and terrariums, the peristaltic metering pump comprising:
a. an inlet port;
b. an outlet port;
c. a stator having an internal surface;
d. a flexible tube having an inlet end connected to the inlet port, and an outlet end connected to the outlet port;
e. a rotor comprising a roller carrier and a plurality of equiangularly disposed rollers rotatably mounted to the roller carrier, a portion of the flexible tube is compressed between at least two rollers and the internal surface, the rollers having a plurality of equiangularly disposed park positions;
f. a stepper motor configured to rotate the pump rotor; and
g. a controller operably connected to the motor and configured to advance the rotor from a known park position during a dosing event in order to dispense a specified volume, the controller determining the number of steps of the stepper motor to dispense the specified volume, and to reverse the motor a number of steps to return at least one of the rollers to one of the plurality of park positions after completion of the dosing event.
2 . The pump of claim 1 , wherein the flexible tube is positioned within the stator between the internal surface and the rotor.
3 . The pump of claim 1 , wherein the roller carrier comprises a flat plate having a center fixed to a motor shaft of the motor.
4 . The pump of claim 1 , wherein the controller is further configured to track the number of steps the motor runs in reverse and to store in a memory the number of steps.
5 . The pump of claim 4 , wherein the controller is configured to forward the motor the number of stored steps before starting a metering cycle.
6 . The pump of claim 1 , wherein the dosing event comprises a plurality of dosing events and the controller is configured to commence each dosing event at one of the park positions.
7 . The pump of claim 1 , wherein the controller is configured to reverse the motor and position the rotor so at least one of the rollers is at a predefined park position after the dosing event.
8 . The pump of claim 7 , wherein the number of park positions is equal to the number of rollers.
9 . The pump of claim 1 , wherein the controller includes a lookup table that correlates volume to be dosed with the number of steps of the stepper motor.
10 . The pump of claim 1 , wherein the controller is configured to operate the stepper motor by microstepping.
11 . The pump of claim 1 , wherein the controller outputs pulse width modulated control pulses to the stepper motor.
12 . A peristaltic metering pump for aquariums, vivariums and terrariums, comprising:
a. housing, the housing including an inlet port, an outlet port, and a stator having an internal surface;
b. a flexible tubing having an inlet end connected to the inlet port and an outlet end connected to the outlet port, at least a portion of the tubing juxtaposed to the internal surface;
c. a rotor comprising a roller carrier having a plurality of equiangularly disposed arms, each arm has a roller rotatably mounted thereto, a portion of the tubing is compressed between at least one roller and the internal surface;
d. a stepper motor operably connected to the pump rotor; and
e. a controller operably connected to the motor and configured to advance the rotor from a known park position during each one of a plurality of dosing events in order to dispense a specified volume from the tubing and to reverse the motor and return the rollers to the known park position after completion of each dosing event.
13 . The pump of claim 12 , wherein the controller is further configured to track the number of steps the motor runs in reverse and to store in memory the number of steps.
14 . The pump of claim 13 , wherein the controller is configured to forward the motor the number of stored steps before starting a metering cycle.
15 . The pump of claim 12 , wherein the controller is configured to reverse the motor and position the rotor so at least one of the rollers is at the known park position after each dosing event, and wherein the number of park positions equals the number of arms.
16 . The pump of claim 12 , wherein the controller is configured to operate the stepper motor by microstepping.
17 . The pump of claim 16 , wherein the controller outputs pulse width modulated control pulses to the stepper motor.
18 . The pump of claim 17 , wherein the controller is further configured to track the number of steps the motor runs in reverse and to store in a memory the number of steps, and wherein the controller is configured to forward the motor the number of stored steps before starting each dosing event.
19 . The pump of claim 1 , wherein the pump is operably associated with one of an aquarium, vivarium and terrarium.
20 . The pump of claim 12 , wherein the pump is operably associated with one of an aquarium, vivarium and terrarium.