Pressure gage and switch

• US 20040237660A1
• Filed: 05/27/2004
• Published: 12/02/2004
• Est. Priority Date: 05/29/2003
• Status: Active Grant

• Current Assignee: Dwyer Instruments Incorporated (Dwyer Instruments)
• Original Assignee: Dwyer Instruments Incorporated (Dwyer Instruments)
• Inventors: Palmer, Brian L., Krueger, Ronald R., Heuer, Daniel A.
• Granted Patent: US 6,981,421 B2
• Time in Patent Office: Days
• US Class Current: 73/735
• CPC Class Codes: G01L 7/084 with mechanical transmitting or indicating means
• CPC Class Codes: G01L 9/0041 Transmitting or indicating the displacement of flexible diaphragms
• CPC Class Codes: G01L 9/14 involving the displacement of magnets, e.g. electromagnets

Abstract

A pressure gage adapted to provide a mechanical indication of a sensed pressure and to provide an electrical signal indicative of the sensed pressure. The pressure gage includes a housing having a first fluid pressure chamber, a second fluid pressure chamber, and flexible diaphragm separating the first fluid pressure chamber from the second fluid pressure chamber. A magnet is coupled to the diaphragm such that movement of the diaphragm causes a related movement of the magnet. A helix is located adjacent to the magnet and a pointer is attached to the helix for conjoint rotation with a helix about a rotational axis. A Hall effect sensor is also located adjacent the magnet. Movement of the magnet in response to movement of the diaphragm rotates the helix and the pointer to provide a mechanical indication of the pressure sensed by the diaphragm, and the movement of the magnet causes the Hall effect sensor to generate an electrical signal indicative of the pressure sensed by the diaphragm.

Claims

1. A pressure gage adapted to provide a mechanical indication of a sensed pressure and to provide an electrical signal indicative of the sensed pressure, said pressure gage comprising:

a first inlet port adapted to be placed in fluid communication with a first fluid source;

a second inlet port adapted to be placed in fluid communication with a second fluid source;

a housing including a first fluid pressure chamber in fluid communication with said first inlet port, a second fluid pressure chamber in fluid communication with said second inlet port, and a flexible diaphragm separating said second fluid pressure chamber from said first fluid pressure chamber;

a magnet coupled to said diaphragm such that movement of said diaphragm causes a related movement of said magnet;

a helix located adjacent said magnet, said helix adapted to rotate about an axis;

a pointer attached to said helix for conjoint rotation with said helix about said axis; and

a Hall effect sensor located adjacent said magnet;

whereby movement of said magnet in response to movement of said diaphragm rotates said helix and said pointer to provide a mechanical indication of the pressure sensed by said diaphragm, and said movement of said magnet causes said Hall effect sensor to generate an electrical signal indicative of the pressure sensed by said diaphragm.

5. The pressure gage of claim 1 including a leaf spring attached at a first end to said housing, said magnet attached to a second end of said leaf spring, and a linkage coupling said leaf spring to said diaphragm, whereby movement of said diaphragm provides a related movement of said magnet through said linkage.

6. The pressure gage of claim 1 wherein said magnet is located between said helix and said Hall effect sensor.

7. The pressure gage of claim 1 wherein said housing includes an outer circumference, and one or more connector members attached to said housing, each connector member including a first end pivotally attached to said housing and a second end adapted to be attached to a structure, each said connector member being selectively pivotal between an outwardly extended position wherein said second end of said connector member is located outwardly beyond said outer circumference of said housing for attachment to the structure, and a retracted position wherein said connector member does not extend outwardly beyond said outer circumference of said housing.

8. The pressure gage of claim 1 including a cover removably attached to said housing, said cover including a lens and a generally circular rim, said rim including a plurality of outwardly extending tabs and a first recess, said housing including a generally circular wall adapted to removably receive said rim of said cover, said circular wall of said housing including a plurality of generally L-shaped slots, each slot adapted to receive a respective tab of said cover and thereby connect said cover to said housing, said circular wall of said housing including a second recess that is adapted to align with said first recess of said cover, and a locking clip adapted to be removably inserted into said first and second recesses to prevent rotation of said cover with respect to said housing, said locking clip being selectively removable from said first and second recesses to allow rotation of said cover with respect to said housing.

10. The pressure gage of claim 1 including a relay and a switch, the switch adapted to be manually activated to select a pressure at which the relay will activate when the Hall effect sensor sends an electrical signal corresponding to the selected pressure.

11. The pressure gage of claim 10 including a first pressure point indicator located on a face plate at a first end of said housing, and a second pressure point indicator located at a second end of said housing, said first and second pressure point indicators adapted to indicate when the pressure selected with said pressure set point switch has been sensed.

12. The pressure gage of claim 1, further including means for selecting a pressure setting.

13. The pressure gage of claim 12, further including means for amplifying the signal generated by the Hall effect sensor, and means for controlling relays.

14. The pressure gage of claim 1, further including:

an amplifier for amplifying the signal generated by the Hall effect sensor;

memory for storing pressure set point values; and

a microprocessor adapted to compare the amplified signal with said pressure set point values.

15. The pressure gage of claim 14 further including a relay electrically connected to said microprocessor, said microprocessor actuating said relay in response to the pressure set point values and the signal generated by the Hall effect sensor.

16. The pressure sensor of claim 1, further including:

means for amplifying said signal generated by the Hall effect sensor;

means for setting and means for storing a pressure set point value;

means for comparing said Hall effect sensor signal and said stored pressure set point value, and

means for activating an electric circuit in response to the result of the comparison.

17. The pressure gage of claim 14, further including an indicator for visually displaying the state of the relay.

18. The pressure gage of claim 1, further including:

a first amplifier stage electrically connected to the Hall effect sensor;

a second amplifier stage electrically connected to the first amplifier stage, the gain of the second stage being selectable by the user of the gage;

a microprocessor electrically connected to the second amplifier stage to receive an amplified signal;

a memory electrically connected to said microprocessor, said memory storing a pressure set point value; and

a relay electrically connected to said microprocessor, said microprocessor controlling the state of the relay in response to a comparison between the amplified signal and the stored pressure set point value.

19. The pressure gage of claim 18, further including a visual indicator for indicating the state of the relay.

2. The pressure gage of clam 1 wherein said housing includes a head housing and a back plate attached to said head housing, said diaphragm including a peripheral edge located between said head housing and said back plate, said first fluid pressure chamber being located between said diaphragm and said back plate and said second fluid pressure chamber being located between said diaphragm and said head housing.

3. The pressure gage of claim 2 wherein said back plate includes a fluid conduit having a first end and a second end, said first inlet port being in fluid communication with said fluid conduit, said fluid conduit being in fluid communication with said first fluid pressure chamber.

4. The pressure gage of claim 3 including an over pressure regulator, said over pressure regulator including a stud located within and movably attached to said fluid conduit of said back plate, and a stop member attached to said stud and located in said first fluid pressure chamber, said stop member being selectively positionable with respect to said diaphragm such that said stop member is adapted to prevent movement of said diaphragm beyond a selected position to prevent said diaphragm from moving said magnet beyond a selected position.

9. The pressure gage of claim 2 including a body housing attached to said back plate, said body housing including a first fluid conduit providing fluid communication between said inlet port and said fluid passage of said back plate, and a second fluid conduit providing fluid communication between said second inlet port and said second fluid pressure chamber.

20. A method of calibrating a pressure gage having two pressure indicators both being driven by a magnet, the steps including:

providing a pressure gage having a diaphragm, said diaphragm being coupled to the magnet;

providing a first indicator, the first indicator being coupled to the magnet;

providing a second indicator, said indicator being coupled to the magnet;

setting the first indicator to a desired value;

setting the second indicator to a desired value.

21. The method of claim 20, where the first indicator is a mechanical gage, said mechanical gage including a helix and a pointer, said helix located adjacent the magnet, the second indicator being a Hall effect sensor located adjacent said magnet, and further including electronics to process the output of the Hall effect sensor to the desired value.

22. The method of claim 22, where the desired value is a range of values.

23. A method of calibrating a pressure gage providing a mechanical indication of sensed pressure, and an electrical signal indicative of sensed pressure, including the steps of:

providing a pressure gage including, a first inlet port adapted to be placed in fluid communication with a first fluid source;

a second inlet port adapted to be placed in fluid communication with a second fluid source;

a housing including a first fluid pressure chamber in fluid communication with said first inlet port, a second fluid pressure chamber in fluid communication with said second inlet port, and a flexible diaphragm separating said second fluid pressure chamber from said first fluid pressure chamber;

a magnet coupled to said diaphragm such that movement of said diaphragm causes a related movement of said magnet;

a helix located adjacent said magnet, said helix adapted to rotate about an axis;

a pointer attached to said helix for conjoint rotation with said helix about said axis; and

a Hall effect sensor located adjacent said magnet;

whereby movement of said magnet in response to movement of said diaphragm rotates said helix and said pointer to provide a mechanical indication of the pressure sensed by said diaphragm, and said movement of said magnet causes said Hall effect sensor to generate an electrical signal indicative of the pressure sensed by said diaphragm;

providing an amplifier connected to the Hall effect sensor;

setting the pointer to a desired position; and

adjusting the amplifier to produce a desired signal, said signal corresponding to the position of the pointer.