Detection of a plunger position in an irrigation control device

Patent metadata

Field	Value
Publication number	US-9618137-B2
Application number	US-201314133595-A
Country	US
Kind code	B2
Filing date	Dec 18, 2013
Priority date	Dec 18, 2013
Publication date	Apr 11, 2017
Grant date	Apr 11, 2017

Abstract

Some embodiments provide irrigation valve control apparatuses comprising: a solenoid configured to cooperate with a plunger; an input stimulus source coupled with the solenoid and configured to apply an input stimulus while a plunger drive signal is not being applied and that is sufficiently small to not cause the plunger to move; sampling circuitry configured to measure one or more voltage measurements corresponding to one or more voltages across the solenoid, wherein the one or more voltage measurements are dependent upon the current position of the plunger relative to the solenoid; and control circuitry cooperated with the sampling circuitry to receive the one or more voltage measurements from the sampling circuitry, wherein the control circuitry is configured to determine whether the plunger is in one of the open and closed positions based on the one or more voltage measurements.

First claim

What is claimed is:

1. An irrigation valve control apparatus comprising:
a solenoid configured to cooperate with a plunger and to receive a plunger drive signal from plunger activation circuitry, wherein the plunger drive signal is configured to induce a magnetic field relative to the solenoid that causes the plunger to change positions between open and closed positions;
an input stimulus source coupled with the solenoid and configured to apply an input stimulus into the solenoid at a time while the plunger drive signal is not being applied to the solenoid, wherein the input stimulus is sufficiently small that the input stimulus applied to the solenoid does not cause the plunger to move from a current position, and wherein the input stimulus comprises multiple input stimulus signals having different resonant frequencies that are sequentially applied into the solenoid;
sampling circuitry configured to measure one or more voltage measurements corresponding to one or more voltages across the solenoid, wherein the one or more voltage measurements are dependent upon the current position of the plunger relative to the solenoid in response to applying the input stimulus to the solenoid; and
control circuitry cooperated with the sampling circuitry to receive the one or more voltage measurements from the sampling circuitry, wherein the control circuitry is configured to determine whether the plunger is in one of the open and closed positions based on the one or more voltage measurements.

2. The apparatus of claim 1 , further comprising:
the plunger positioned relative to the solenoid, wherein the plunger is configured to be movable between the open and closed positions in response to the magnetic field generated by the solenoid in response to the plunger drive signal applied to the solenoid by the plunger activation circuitry.

3. The apparatus of claim 1 , wherein the control circuitry, in determining whether the plunger is in one of the open and closed positions, is configured to evaluate the one or more voltage measurements relative to a first threshold and determine whether the plunger is in one of the open and closed positions as a result of a relationship between the one or more voltage measurements and the first threshold.

4. The apparatus of claim 3 , wherein the control circuitry is further configured to evaluate the one or more voltage measurements relative to a second threshold, and determine whether the plunger is in the other of the open and closed positions as a function of a second relationship between the one or more voltage measurements and the second threshold.

5. The apparatus of claim 4 , wherein the control circuitry is further configured to identify that the plunger is in an unknown position as the result of the first relationship between the one or more voltage measurements and the first threshold and the second relationship between the one or more voltage measurements and the second threshold.

6. The apparatus of claim 1 , wherein the control circuitry is further configured to evaluate the one or more voltage measurements relative to a third threshold, and to determine whether the plunger is removed from a position cooperated with the solenoid as a result of a relationship between the one or more voltage measurements and the third threshold.

7. The apparatus of claim 1 , further comprising:
a resistance-capacitance circuit (RC circuit) coupled with the solenoid at a first terminal of the solenoid forming an inductance, resistance and capacitance circuit (LRC circuit), wherein the RC circuit comprises a first resistor and a first capacitor cooperatively coupled with the solenoid.

8. The apparatus of claim 7 , wherein the sampling circuitry in taking each of the one or more voltage measurements is configured to take multiple measurements over time of the voltage across the solenoid in response to the application of the input stimulus to the LRC circuit.

9. The apparatus of claim 7 , wherein the sampling circuitry is coupled with the solenoid at a connection between the first terminal of the solenoid and the RC circuit.

10. The apparatus of claim 1 , wherein the plunger activation circuitry is distinct from the sampling circuitry and the control circuitry.

11. The apparatus of claim 1 , wherein the input stimulus comprises at least one of a sine wave signal, a periodic square wave signal, and a single square pulse signal.

12. The apparatus of claim 1 , wherein the plunger drive signal is distinct from the input stimulus source.

13. The apparatus of claim 1 , wherein the sampling circuitry in taking each of the one or more voltage measurements is configured to take the one or more voltage measurements after a predefined period of time following the input stimulus being applied to the solenoid.

14. The apparatus of claim 1 , further comprising:
a gain stage coupled between the solenoid and the sampling circuitry, wherein the gain stage is configured to amplify, prior to taking the one or more voltage measurements, an amplitude-modulated pulse induced at least in part by the solenoid in response to the input stimulus producing an amplified, amplitude-modulated pulse corresponding to voltage across the solenoid; and
wherein the sampling circuitry in measuring the one or more voltage measurements is configured to measure the one or more voltage measurements of the amplified, amplitude-modulated pulse corresponding to the voltage across the solenoid with a resulting increased dynamic range of the sampling circuitry allowing the utilization of a greater number of bits to digitally represent the sampled signal than available without the gain stage.

15. The apparatus of claim 1 , wherein the sampling circuitry is configured to take multiple voltage measurements following the application of the input stimulus;
wherein the control circuitry is configured to receive the multiple voltage measurements, to cooperate the multiple voltage measurements calculating a cooperative measurement; and
wherein the control circuitry is configured, when evaluating the one or more voltage measurements, to evaluate the cooperative measurement relative to a first threshold, and determine whether the plunger is in one of the closed position and the open position as a result of a relationship between the cooperative measurement and the first threshold.

16. The apparatus of claim 1 , further comprising:
boost circuitry coupled with a multi-wire path comprising at least two wires, wherein the multi-wire path delivers power; and
boost control circuitry configured to determine whether a voltage level on the multi-wire path is below a plunger drive signal threshold and activates the boost circuitry;
wherein the boost circuitry is configured to increase a voltage of the plunger drive signal applied to the solenoid to induce the movement of the plunger to change positions between the open and closed positions.

17. The apparatus of claim 16 , wherein the boost control circuitry, in response to determining that the voltage level on the multi-wire path is below the plunger drive signal threshold, is further configured to generate a pulse width modulated (PWM) signal applied to the boost circuitry; and
wherein the boost circuitry is configured to generate an increased voltage and charge one or more charge storage circuitry, over a period of time, to a voltage at least equal to the plunger drive signal threshold in response to the PWM signal.

18. The apparatus of claim 1 , further comprising:
temperature sensing circuitry coupled with the control circuitry, wherein the temperature s

Assignees

• Rain Bird Corp

Inventors

• Ferrer Herrera Manuel J
• Lurcott Steven M
• Roper Todd K

Classifications

• Y10T137/8242

  Electrical · CPC title

• H01F7/1844

  Monitoring or fail-safe circuits (for relays H01H47/002) · CPC title

• H01F2007/185

  with armature position measurement · CPC title

• A01G25/16

  Control of watering · CPC title

• F16K31/06

  using a magnet {, e.g. diaphragm valves, cutting off by means of a liquid} · CPC title