Flow meter for dosing pumps

1 . A flow meter for a pulsed fluid stream which performs a succession of pulses, comprising:

a flow sensor body defining an internal flow channel having an inlet and an outlet, the flow channel configured to allow flow of the fluid stream in a direction from said inlet to said outlet;

a float structure movable in said flow channel in said direction by the pulsed stream and being biased to perform a movement counter to said direction between successive pulses of the fluid stream, the float structure comprising a float body and a ferromagnetic body;

first, second and third coils surrounding first, second and third portions of the flow sensor body;

the second coil configured as a drive coil for connection to an AC signal generator and situated between the first and third coils along the float body;

each of said first and third coils configured to generate induced voltage signals in response to the position of said float structure in said flow channel; and

an electronics module connected to the first, second and third coils, the electronics module including:

the AC signal generator connected to the second coil to drive the second coil with AC signals;

the module configured to measure the position of the float structure in said flow channel, the module responsive to the induced voltage signals from each of the first and third coils and configured to determine the first peak voltage of the first coil with the float structure at rest between pulses of the fluid stream and the third peak voltage of the third coil during each pulse of the fluid stream;

the module configured to generate a flow meter signal indictive of a fluid flow quantity passed through the channel.

2 . The flow meter of claim 1 , wherein the electronics module includes an electronic controller responsive to signals indicative of the first peak voltage and the third peak voltage.

3 . The flow meter of claim 2 , wherein the electronic controller is configured to correlate the signals indicative of the first peak voltage and the third peak voltage to a fluid quantity passed through the channel during a pulse.

4 . The flow meter of claim 3 , wherein the electronic controller comprises a microcontroller.

5 . The flow meter of claim 1 wherein the sensor body is configured for vertical mounting so that gravity biases the float structure to a rest position between pulses.

6 . The flow meter of claim 1 wherein first and second check valves are positioned in fluid communication with the respective inlet and outlet of the channel.

7 . A fluid dispensing system comprising:

a dosing pump configured to provide the pulsed fluid stream of claim 1 ; and

the flow meter of claim 1 .

8 . A flow meter for a pulsed fluid stream which performs a succession of pulses, comprising:

a flow sensor body defining an internal flow channel having an inlet and an outlet, the flow channel configured to allow flow of the fluid stream in a direction from said inlet to said outlet:

a float structure movable in said flow channel in said direction by the pulsed stream and being biased to perform a movement counter to said direction between successive pulses of the fluid stream, the float structure comprising a float body and a ferromagnetic body:

first, second and third coils surrounding first, second and third portions of the flow sensor body;

the second coil configured as a drive coil for connection to an AC signal generator and situated between the first and third coils along the float body;

each of said first and third coils configured to generate induced voltage signals in response to the position of said float structure in said flow channel; and

an electronics module connected to the first, second and third coils, the electronics module including:

the AC signal generator connected to the second coil to drive the second coil with AC signals;

the module configured to measure the position of the float structure in said flow channel, the module responsive to the induced voltage signals from each of the first and third coils and configured to determine the first peak voltage of the first coil with the float structure at rest between pulses of the fluid stream and the third peak voltage of the third coil during each pulse of the fluid stream;

the module configured to generate a flow meter signal indictive of a fluid flow quantity passed through the channel; and

wherein the float structure comprises a plurality of elongated channels extending longitudinally along the periphery of the float body.

9 . The flow meter of claim 8 , wherein the float body comprises a sheath fabricated of a plastic material, and the ferromagnetic body is a ferrite rod disposed within the sheath.

10 . A method for measuring fluid flow of a pulsed fluid stream which performs a succession of pulses, comprising:

providing a sensor body defining a flow channel for the flow of the fluid stream and having an inlet and an outlet;

positioning a movable float structure in the flow channel and being biased to perform a movement counter to the direction of fluid flow between successive pulses of the fluid stream, the float structure comprising a ferromagnetic body;

providing first, second and third coils surrounding first, second and third portions of the sensor body the second coil disposed between the first and third coils along the sensor body;

driving the second coil with an AC signal to generate induced voltage signals in the first and third coils in response to the position of said float structure in said channel; and

analyzing the induced voltage signals in the first and third coils to determine the peak voltage of the first coil with the float structure at rest between pulses and the peak voltage of the third coil during each pulse and generating a flow meter signal indictive of a fluid flow passed through the channel.

11 . The method of claim 10 , further comprising:

calculating a stroke rate by the declining detections from one pulse to another.

12 . The method of claim 10 , wherein the float structure comprises a sheath having a plurality of elongated channels extending longitudinally along the periphery of the float structure, the method further comprising selecting the size of the channels in dependence on fluid characteristics and fluid flow rate.

13 . The method of claim 10 , wherein said analyzing includes correlating said peak voltage of the first coil and said peak voltage of the third coil to a fluid quantity passed through the channel during a pulse.

14 . The method of claim 10 , further comprising:

in a calibration step, measuring a fluid quantity passed through the channel for a predetermined set of values of said peak voltages of the first and third coils; and

storing data representative of a calibrated fluid quantity in a digital memory.

15 . The method of claim 10 , wherein said step of providing a sensor body defining a flow channel includes positioning the sensor body so that the flow channel is oriented vertically so that gravity biases the float structure to a rest position between pulses.

16 . The method of claim 10 , further comprising:

fluidically coupling the sensor body to a dosing pump to provide the pulsed fluid stream.