Hall effect pressure transducer

• US 4,936,148 A
• Filed: 10/17/1988
• Issued: 06/26/1990
• Est. Priority Date: 10/17/1988
• Status: Expired due to Fees

• Current Assignee: Anent Systems Corporation
• Original Assignee: Anent Systems Corporation
• Inventors: Shaw, Clyde C., Orio, John H., Wakeman, William G.
• Primary Examiner(s): WOODIEL, DONALD
• Application Number:
  US07/258,620
• Time in Patent Office: 617 Days
• Field of Search: 73/722, 73/728, 73/719, 73/725, 338/32 H, 338/42, 336/30
• US Class Current: 73/728
• CPC Class Codes: G01L 9/14 involving the displacement of magnets, e.g. electromagnets

Abstract

A Hall effect pressure transducer incorporates a pressure-deflection diaphragm which has patterned depressions therein to enhance linearity of response; an O-ring diaphragm seal which seals the diaphragm against pressure leaks without affecting the linearity of response; a pair of magnets, preferably rectangular, oriented with their North-South axes oppositely parallel, and oriented transverse to the deflection axis of the diaphragm to provide a uniform magnetic field gradient and sensitive, accurate, linear response of the transducer to either positive or negative pressure-induced deflections of the diaphragm.

Claims

1. A pressure transducer providing a voltage output which is a linear function of pressure, comprising:

a housing;

a diaphragm within said housing dividing said housing into a reference pressure chamber and a sample pressure chamber, the latter adapted for receiving pressurized fluid at a selected pressure;

said diaphragm having a pattern of depressions for providing deflection of said diaphragm along a direction coinciding with an axis of rotation thereof, said deflection closely approximating a linear output response function of the applied pressure;

an O-ring between the periphery of said diaphragm and said housing non-fixedly sealing the periphery of said diaphragm against the interior of said housing;

magnet means providing a uniform magnetic field gradient and comprising a pair of magnets mounted together along mating planar surfaces to the diaphragm and with their North and South axes oriented parallel and oppositely to one another and transverse to said deflection axis, for providing a uniformly varying magnetic field in the region of said interface; and

a Hall effect sensor being mounted to the housing and closely adjacent to said magnet means and within the uniform magnetic field gradient proximate said interface.

2. The transducer of claim 1, wherein said diaphragm and said housing comprise at least one peripheral protuberance and mating depression for preventing relative movement between said diaphragm and said planar sensor.

3. The transducer of claim 1 or 2, wherein said magnets are rectangular or square.

4. The transducer of claim 3, further comprising a mask of magnetic field interposed between said magnet means and said sensor and having an aperture therein for shunting the magnetic lines of force except through said aperture.

5. The transducer of claim 4, wherein said aperture is aligned with and intercepts the lines of flux emanating from the region of said interface.

6. The transducer of claim 5, wherein said magnets are rectangular or square.

7. A pressure transducer for providing a voltage output which is a linear function of pressure and comprising:

a housing;

a diaphragm within said housing dividing said housing into a reference pressure chamber and a test chamber adapted for receiving fluid at a selected pressure;

said diaphragm having a pattern of depressions that allow deflection of said diaphragm along an axis which provides a close approximation to a linear function of the test fluid pressure along a deflection axis of the diaphragm;

an O-ring between the periphery of said diaphragm and said housing non-fixedly sealing the periphery of said diaphragm against the interior of said housing;

magnet means comprising at least a magnet mounted to said diaphragm and oriented with the North-South axis thereof generally parallel to the plane of said diaphragm and transverse to an axis of deflection of said diaphragm; and

a Hall effect sensor mounted to said housing and closely adjacent to and within the magnetic field of said magnet means; and

further comprising a mask of magnetic material between said magnet means and said sensor and having an aperture therein for shunting the magnetic lines of force except those through said aperture, thereby to transmit a uniform magnetic field to said sensor.

8. The transducer of claim 7, wherein said diaphragm and said housing comprise at least one peripheral protuberance and mating depression for preventing movement of the diaphragm and associated movement of the magnet means in at least one of axial rotation and a radial direction with respect to the face of said fixed position sensor.

9. The transducer of claim 7, wherein said diaphragm and said housing comprise at least one peripheral protuberance and mating depression for preventing movement of the diaphragm and associated movement of the magnet means in at least one of axial rotation and a radial direction with respect to the face of said fixed position sensor.