Method and apparatus for flow control of NH3

• US 6,694,825 B2
• Filed: 03/27/2002
• Issued: 02/24/2004
• Est. Priority Date: 05/29/1998
• Status: Expired due to Term

• Current Assignee: Parker Intangibles LLC (Parker-Hannifin Corporation)
• Original Assignee: PGI International LTD (Parker-Hannifin Corporation)
• Inventors: Cessac, Kevin J., Nimberger, Spence M.
• Primary Examiner(s): Lefkowitz, Edward
• Assistant Examiner(s): Mack, Corey D.
• Application Number:
  US10/107,846
• Publication Number:
  US 20020170362A1
• Time in Patent Office: 699 Days
• Field of Search: 738/617.7, 738/617.6, 738/617.5, 732/041.8, 732/041.9, 732/041.5, 732/041.6, 738/617.4, 324/207.11, 324/207.12, 324/207.13
• US Class Current: 73/861.77
• CPC Class Codes: A01C 23/007 Metering or regulating systems
• CPC Class Codes: A01C 23/024 for ammonia
• CPC Class Codes: G01F 1/115 with magnetic or electromagnetic coupling to the indicating device
• CPC Class Codes: G01F 1/24 with magnetic or electric coupling to the indicating device

Abstract

An apparatus and method for accurately controlling the amount of NH₃ to be applied to a field by measuring the NH₃ flow rate without condensing or cooling the NH₃. The system includes a control station 12 on the vehicle with a tachometer 12A or a GPS system for providing a vehicle speed signal to a control panel 13. The control panel includes a toggle switch 17 for adjusting the opening or closing of a valve 52 in the flow line to regulate the flow through the system, although the control panel alternatively may automatically control the valve 52. The vehicle transports a tank 20 containing liquid NH₃ and a tool bar 30 for distributing the NH₃ to the soil. After flowing through the flow meter 40,60, 130, the NH₃ is conducted to the soil through a series of hoses, fittings, a distributor, and tubing. The flow meter transmits a signal to the control panel, which is converted to a corrected flow rate signal in response to a fixed value vaporization correction factor. The temperature of the NH₃ is also measured to correct for density variations. An improved variable area meter 60, 130 uses a hall effect sensor 72 and a magnet 68 mounted on a rotatable vane shaft 70 to overcome problems with prior flow meters. The improved meter 60, 130 is ideally suited for measuring the fluid flow of a low temperature vaporization liquid, such as anhydrous ammonia, propane and butane.

Claims

1. A variable area flow meter positionable along a flow line for sensing the flow rate of fluid through the flow line and outputting a signal in response thereto, the flow meter comprising:

a housing having an internal cavity with a fluid inlet and a fluid outlet each for interconnection with the flow line;

a vane member rotatable about a shaft axis and moveable within the internal cavity in the housing in response to fluid flow to vary the flow area as a function of the flow rate through the meter, the position of the vane member within the housing being related to the flow rate through the meter;

a magnet fixedly positioned on the vane member within the cavity and rotatable with the vane member about the shaft axis;

a biasing member for biasing the vane member in a preselected position within the housing; and

a sensor fixed to the housing exterior of the cavity for outputting a flow rate signal in response to the position of the magnet with respect to the housing, the flow rate signal being indicative of the rotational position of the vane member and thus the flow rate through the housing.

2. The variable area flow meter as defined in claim 1, wherein the biasing member is a coil spring.

3. The variable area flow meter as defined in claim 1, wherein the magnet comprises a unitary magnet having a curvilinear outer surface, such that a substantially uniform gap exists between the magnet and the sensor as the magnet rotates within the cavity.

4. The variable area flow meter as defined in claim 3, wherein the sensor is a hall effect sensor which outputs an electrical signal functionally related to the flux density of the magnet.

5. The variable area meter as defined in claim 1, further comprising:

a flow rate correction device for receiving the flow rate signal from the sensor and outputting a corrected flow rate signal indicative of the actual flow rate through the meter.

6. The variable area flow meter as defined in claim 5, further comprising:

a temperature sensor for sensing the temperature of fluid in the flow line and outputting a temperature signal to the correction device in response thereto.

7. The variable area flow meter as defined in claim 1, wherein the flow rate correction device is a computer.

8. The variable area flow meter as defined in claim 1, wherein the system uses a non-magnetic wall portion of the housing separating the unitary magnet from the vane member.

9. The variable area flow meter as defined in claim 1, wherein the vane member is not sealed to the housing.

10. A variable area flow meter positionable along a flow line for sensing the flow rate of fluid through the flowline and outputting a signal in response thereto, the flow meter comprising:

a housing having an internal cavity with a fluid inlet and a fluid outlet each for interconnection with the flow line;

a vane member rotatable about a shaft axis and moveable within the internal cavity in the housing in response to fluid flow to vary the flow area as a function of the flow rate through the meter, the position of the vane member within the housing being related to the flow rate through the meter;

a unitary magnet fixedly positioned on the vane member within the cavity and rotatable with the vane member about the shaft axis, the unitary magnet having a curvilinear outer surface, such that a substantially uniform gap exists between the magnet and the sensor as the magnet rotates within the cavity;

a coil member for biasing the vane member in a preselected position within the housing; and

a sensor fixed to the housing exterior of the cavity for outputting a flow rate signal in response to the position of the magnet with respect to the housing, the flow rate signal being indicative of the rotational position of the vane member and thus the flow rate through the housing.

11. The variable area flow meter as defined in claim 10, wherein the sensor is a hall effect sensor which outputs an electrical signal functionally related to the flux density of the magnet.

12. The variable area meter as defined in claim 10, further comprising:

a flow rate correction device for receiving the flow rate signal from the sensor and outputting a corrected flow rate signal indicative of the actual flow rate through the meter.

13. The variable area flow meter as defined in claim 12, wherein the flow rate correction device is a computer.

14. The variable area flow meter as defined in claim 10, further comprising:

a temperature sensor for sensing the temperature of fluid in the flow line and outputting a temperature signal to the correction device in response thereto.

15. The variable area flow meter as defined in claim 10, wherein the system uses a non-magnetic wall portion of the housing separating the unitary magnet from the vane member.

16. The variable area flow meter as defined in claim 10, wherein the vane member is not sealed to the housing.

17. A variable area flow meter positionable along a flow line for sensing the flow rate of fluid through the flow line and outputting a signal in response thereto, the flow meter comprising:

a housing having an internal cavity with a fluid inlet and a fluid outlet each for interconnection with the flow line;

a vane member rotatable about a shaft axis and moveable within the internal cavity in the housing in response to fluid flow to vary the flow area as a function of the flow rate through the meter, the position of the vane member within the housing being related to the flow rate through the meter;

a magnet fixedly positioned on the vane member within the cavity and rotatable with the vane member about the shaft axis;

a biasing member for biasing the vane member in a preselected position within the housing;

a sensor fixed to the housing exterior of the cavity for outputting a flow rate signal in response to the position of the magnet with respect to the housing, the flow rate signal being indicative of the rotational position of the vane member and thus the flow rate through the housing; and

a flow rate correction computer for receiving the flow rate signal from the sensor and outputting a corrected flow rate signal indicative of the actual flow rate through the meter.

18. The variable area flow meter as defined in claim 17, wherein the biasing member is a coil spring.

19. The variable area flow meter as defined in claim 17, wherein the magnet comprises a unitary magnet having a curvilinear outer surface, such that a substantially uniform gap exists between the magnet and the sensor as the magnet rotates within the cavity.

20. The variable area flow meter as defined in claim 17, wherein the sensor is a hall effect sensor which outputs an electrical signal functionally related to the flux density of the magnet.

21. The variable area flow meter as defined in claim 17, further comprising:

a temperature sensor for sensing the temperature of fluid in the flow line and outputting a temperature signal to the correction device in response thereto.