Remote pressure indicator for sealed vessels including vehicle tires

• US 6,520,006 B2
• Filed: 08/02/2001
• Issued: 02/18/2003
• Est. Priority Date: 08/10/2000
• Status: Expired due to Fees

• Current Assignee: Mlho, Inc.
• Original Assignee: Mlho, Inc.
• Inventors: Burns, Alan Alexander
• Primary Examiner(s): Oen, William
• Assistant Examiner(s): FERGUSON SAMRETH, MARISSA LIANA
• Application Number:
  US09/922,395
• Publication Number:
  US 20020038570A1
• Time in Patent Office: 565 Days
• Field of Search: 733/86, 731/46--468, 737/28, 737/08, 340/447, 340/448
• US Class Current: 73/146
• CPC Class Codes: B60C 23/0408 transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver
• CPC Class Codes: B60C 23/0425 Means comprising permanent magnets, e.g. Hall-effect or Reed-switches

Abstract

A compact, robust, and inexpensive magnetically coupled pressure gauge includes a spiral-faced or helical bellows coupled for rotating a magnetic field source (permanent magnet) within a pressure vessel the orientation of which is externally sensed and correlated to pressure within the pressure vessel. Mechanisms of extraneous magnetic field compensation are discussed Applications contemplated include measuring pressure in pressure vessels and pressure of pneumatic vehicle tires without breaching the integrity of the particular pressurized vessels. Embodiments included a visual, manual tire pressure monitoring system.

Claims

1. A magnetically coupled pressure gauge for indicating fluid pressure within a pressure vessel outside the pressure vessel, comprising in combination,

(a) a rotatable sender means mounted inside of the pressure vessel for providing a rotatable magnetic field having a specific direction, the specific direction of the provided magnetic field rotating in a plane parallel to an axis of symmetry of the magnetic field;

(b) a pressure actuated bellows mechanism also mounted inside of the pressure vessel coupled for rotating the sender means rotationally changing orientation of the specific direction of the magnetic field in the plane parallel to the axis of symmetry responsive to variations in fluid pressure within the vessel; and

(c) sensor means mounted outside of the pressure vessel for sensing and indicating orientation of the specific direction of the magnetic field provided by the sender means in the plane parallel its axis of symmetry as rotated to a particular orientation by the pressure actuated bellows mechanism.

2. The magnetically coupled pressure gauge of claim 1 and further including, in combination therewith,

(d) a hermetically sealed sender container secured inside of the pressure vessel to an interior pressure vessel wall surface containing:

(i) the sender means providing the magnetic field mounted for rotation proximate the pressure vessel wall; and

(ii) the pressure actuated bellows mechanism mounted for expansion and contraction within the sealed sender container; and

(iii) means coupling between the bellows mechanism and the sender means for rotating the sender means upon expansion and contraction of the bellows mechanism,

(iv) a fluid having a known pressure;

(e) a pressure vessel fluid port communicating through a wall of the sender container into the pressure actuated bellows mechanism for allowing the bellows mechanism to expand and contract responsive to pressure differences (Δ

p) between the fluid inside of the hermetically sealed sender container and fluids inside of the pressure vessel and rotationally orient the specific direction of the provided magnetic field.

3. The magnetically coupled pressure gauge of claim 2 wherein the pressure actuated bellows mechanism comprises, a helical bellows having a proximate end and a distal end, its distal end being rigidly, and hermetically secured around, and in fluid communication with the pressure vessel fluid port, its proximate end rotating, extending and retracting toward and away from the sender means responsive to the pressure differences (Δ

p) for rotating the sender means.

4. The magnetically coupled pressure gauge of claim 2 wherein the pressure actuated bellows mechanism comprises a spiral-faced, annular bellows having an inner and an outer cylindrical periphery, the inner cylindrical periphery being hermetically secured, coaxially around a stationary cylindrical hub within the sealed sender container, the hub being hermetically secured around the pressure vessel fluid port, and having a fluid passageway communicating between the pressure vessel fluid port into the spiral-faced, annular bellows, the pressure differences (Δ

p) expanding and contracting the spiral-faced bellows rotating its outer cylindrical periphery relative to the stationary cylindrical hub.

5. The magnetically coupled pressure gauge of claim 1 or 2 or 3 or 4 wherein the sender means providing the magnetic field is a permanent magnet producing a magnetic field having axis of symmetry aligned with a north polarity end and a south polarity end of the magnet.

6. The magnetically coupled pressure gauge of claim 1 or 2 or 3 or 4 wherein the pressure vessel comprises a combination of an inflated, annular pneumatic tire hermetically sealed around a wheel rim for a vehicle.

7. The magnetically coupled pressure gauge of claim 1 or 2 or 3 or 4 and further including means for correlating the specific direction of the magnetic field provided by the sender means sensed by the sensor means to pressure within the pressure vessel.

8. The magnetically coupled pressure gauge of claim 2 or 3 or 4 wherein the hermetically seal sender container is evacuated having a fluid pressure less than one standard atmosphere and further including means for correlating the specific direction of the provided magnetic field sensed by the sensor means to pressure within the pressure vessel.

9. The magnetically coupled pressure gauge of claim 2 or 3 or 4 wherein the hermetically seal sender container is pressurized having a fluid pressure greater than one standard atmosphere and further including means for correlating the direction of the provided magnetic field sensed by the sensor means to pressure within the pressure vessel.

10. The magnetically coupled pressure gauge of claim 8 wherein the fluid pressure within the hermetically sealed sender container is less than a maximum expected pressure of a fluid contained within the pressure vessel and wherein the bellows mechanism includes a resisting/restoring elastic response opposing contraction of the bellows.

11. The magnetically coupled pressure gauge of claim 8 wherein the fluid pressure within the hermetically sealed sender container is greater than a minimum expected pressure of a fluid contained within the pressure vessel and wherein the bellows mechanism includes a resisting/restoring elastic response opposing expansion of the bellows.

12. The magnetically coupled pressure gauge of claim 9 wherein the fluid pressure within the hermetically sealed sender container is less than a maximum expected pressure of a fluid contained within the pressure vessel and wherein the bellows mechanism includes a resisting/restoring elastic response opposing contraction of the bellows.

13. The magnetically coupled pressure gauge of claim 9 wherein the fluid pressure within the hermetically sealed sender container is greater than a minimum expected pressure of a fluid contained within the pressure vessel and wherein the bellows mechanism includes a resisting/restoring elastic response opposing expansion of the bellows.

14. The magnetically coupled pressure gauge of claim 6 wherein:

(1) the magnetic field provided by the sender means has north and a south polarity, and

(2) the sender means is mounted with its axis of rotation perpendicularly intersecting the axis of symmetry of that field located midway between the north and south polarity of the provided magnetic field, and

(3) the sensing means for sensing and indicating direction of the magnetic field provided by the sender means outside the tire and wheel rim pressure vessel includes a array of sensing coils, oriented about a sensing axis, the sensing axis being oriented essentially parallel to the axis of rotation of the sender means, the respective sensing coils each having a central coil axis extending radially to the sensing axis in a common plane; and

wherein the sensing means is mounted at a stationary position on the vehicle, proximate the tire and wheel rim, where the axis of rotation of the sender means revolving with the tire and rim sweeps through coincidence with the sensing axis of the sensing means as the tire and rim revolve.

15. The magnetically coupled pressure gauge of claim 7 wherein the specific direction of the magnetic field provided by the sender means is essentially parallel to the axis of symmetry of that magnetic field.

16. The magnetically coupled pressure gauge of claim 15 wherein:

(1) the magnetic field provided by the sender means has north and south polarity, and

(2) the sender means is mounted with its axis of rotation perpendicularly intersecting the axis of symmetry of that field located midway between the north and the south polarity of that field, and

(3) the sensing means for sensing and indicating direction of the magnetic field provided by the sender means outside the pressure vessel includes a array of sensing coils, oriented about a sensing axis, the sensing axis being approximately parallel and coaxial with the axis of rotation of the sender means, the respective sensing coils each having a central coil axis radially extending to the sensing axis in a common plane.

17. The magnetically coupled pressure gauge of claim 15 wherein:

(1) the magnetic field provided by the sender means has north and south polarity, and

(2) the sender means is mounted with its axis of rotation perpendicularly intersecting the axis of symmetry of that field located midway between the north and the south polarity of that field, and

(3) the sensing means for sensing and indicating direction of the magnetic field provided by the sender means outside the pressure vessel includes a array of magneto-resistive magnetic field sensors, oriented about a sensing axis, the sensing axis being approximately parallel and coaxial with the axis of rotation of the sender means.

18. The magnetically coupled pressure gauge of claim 15 wherein:

(1) the magnetic field provided by the sender means has north and south polarity, and

(2) the sender means is mounted with its axis of rotation perpendicularly intersecting the axis of symmetry of that field located midway between the north and the south polarity of that field, and

(3) the sensing means for sensing and indicating direction of the magnetic field provided by the sender means outside the pressure vessel includes a array of Hall effect magnetic field sensors, oriented about a sensing axis, the sensing axis being approximately parallel and coaxial with the axis of rotation of the sender means.

19. The magnetically coupled pressure gauge of claim 6 wherein the pneumatic tire has indicial markings on its exterior surface indicating:

(1) where the sender means is located within the tire/wheel rim pressure vessel,

(2) where the axis of rotation of the sender means is located and

(3) a reference direction for the specific direction of the magnetic field provided by the sender means; and

wherein the sensing means for sensing and indicating the specific direction of the magnetic field provided by the sender means outside the tire/wheel rim pressure vessel includes a sensor casing having exterior indicial markings corresponding to those on the exterior of the tire for manually locating, orienting and aligning the sensing means on the exterior tire surface, the sensing means sensing and indicating the specific direction of the magnetic field provided by the sender means relative to the reference direction indicated by the respective aligned reference direction indicial exterior markings on the tire and sensor casing.

20. The magnetically coupled pressure gauge of claim 15 wherein:

the magnetic field provided by the sender means has north and south polarity, and

(1) the sender means is mounted with its axis of rotation perpendicularly intersecting the axis of symmetry of that field located midway between the north and the south polarity of that field, and

(2) the sensing means for sensing and indicating direction of the magnetic field provided by the sender means outside the pressure vessel comprises, in combination,

(i) a sensor casing located on an exterior surface of the pressure vessel immediately adjacent to the sender means mounted for rotation about a rotating axis within the pressure vessel,

(ii) a permanent sensing magnet providing a sensing magnetic field with north and south polarity mounted for rotation within the casing about a sensing axis perpendicularly intersecting the magnet midway between the north and south polarity of the sensing magnetic field, the sensing axis being oriented in an approximately parallel and coaxial relationship with the axis of rotation of the sender means within the pressure vessel,

whereby, the sensing magnetic field interacting with the magnetic field provided by the sender means rotates the permanent sensing magnet within the sensor casing into opposing polarity alignment with the magnetic field provided by the sender means indicating the specific direction of the magnetic field provided by the sender means.

21. The magnetically coupled pressure gauge of claim 1 or 2 or 3 or 4 and further including magnetic field flux guiding elements of alternatively high magnetic permeability elements and low magnetic permeability elements for preserving the specific direction the magnetic field provided by the sender means and magnetically coupling that field to the sensing means.

22. A method for externally sensing pressure of a fluid within a pressure vessel comprising the steps of:

(a) locating and mounting for rotation, a magnetic field source inside of the pressure vessel containing the fluid for providing a magnetic field having an axis of symmetry rotating in a particular plane;

(b) coupling the magnetic field source to a pressure actuated bellows also located inside of the pressure vessel expanding and contracting responsive to pressure differences Δ

p between fluid pressure inside the pressure vessel and a known fluid pressure, the expansion and contraction of the bellows rotationally orienting the axis of symmetry of the provided magnetic field in the particular plane inside the pressure vessel;

(c) sensing orientation of the axis of symmetry of the provide magnetic field outside the pressure vessel; and

(d) correlating the orientation of the axis of symmetry of the magnetic field sensed to pressure within the pressure vessel.

23. The method for externally sensing pressure within a pressure vessel with a magnetic field of claim 22 and further including the steps of:

(e) encasing the magnetic field source and the pressure actuated bellows within a hermetically sealed container;

(f) pressurizing the hermetically sealed container with a fluid to a known pressure;

(g) establishing fluid communication from outside of the hermetically sealed container to inside of the pressure actuated bellows within the hermetically sealed container; and

(h) integrating the hermetically sealed container with an interior pressure vessel wall surface inside of the pressure vessel.