Pressure sensor

• US 4,905,520 A
• Filed: 10/12/1988
• Issued: 03/06/1990
• Est. Priority Date: 10/16/1987
• Status: Expired due to Fees

• Current Assignee: Bochumer Eisenhutte Heintzmann GmbH & Company (Heintzmann Holding GmbH)
• Original Assignee: Bochumer Eisenhutte Heintzmann GmbH & Company (Heintzmann Holding GmbH)
• Inventors: Nehrlich, Ernst G., Berger, Karl-Heinz
• Primary Examiner(s): WOODIEL, DONALD
• Application Number:
  US07/257,104
• Time in Patent Office: 510 Days
• Field of Search: 73/719, 73/722, 73/725, 73/728, 73/753, 338/32 H
• US Class Current: 73/753
• CPC Class Codes: G01D 5/147 influenced by the movement of a third element, the position of Hall device and the source of magnetic field being fixed in respect to each other
• CPC Class Codes: G01L 9/14 involving the displacement of magnets, e.g. electromagnets

Abstract

The pressure sensor has a mechanical pressure receiving member and a mechanical-electrical transducer connected to it. The transducer comprises a permanent magnet attached with a moving portion of the pressure receiving member which cooperates with a locally fixed Hall-effect sensor mounted on the housing. To linearize the characteristic response curve of the transducer the inner surface of the housing wall is shaped like a funnel in a region between the permenent magnet and the Hall-effect sensor and in the vicinity of the permanent magnet. Because of this geometry the field strength lines are bunched increasingly on increasing separation of the permanent magnet from the Hall-effect sensor so that the field strength at the Hall-effect sensor increases and/or decreases approximately linearly with displacement path of the magnet.

Claims

1. In a pressure sensor with a housing in which a mechanical pressure receiving member and a connected mechanical electrical transducer are located and in which the moving portion of said pressure receiving member is attached at least indirectly with a permanent magnet which cooperates with or acts on a Hall-effect sensor and together with said Hall-effect sensor comprises said transducer, the improvement wherein the cross section of said housing in the vicinity of said permanent magnet and in a region between said permanent magnet and said Hall-effect sensor is designed, adjusted or tuned to attain an approximately linear magnet field strength decrease at said Hall-effect sensor and a linear characteristic response curve on motion of said permanent magnet from one near end position to another far end position of said permanent magnet, said housing having a round cross section in said region between said permanent magnet and said Hall Effect sensor, the inner surface of said housing wall in reference to said near end position adjacent said Hall-effect sensor of said permanent magnet being substantially cylindrical in said vicinity of said permanent magnet and substantially conical in said region between said Hall-effect sensor and said permanent magnet tapering in the direction of said permanent magnet, the outer surface of said housing wall being substantially cylindrical.

2. In a pressure sensor with a housing in which a mechanical pressure receiving member and a connected mechanical-electrical transducer are located and in which the moving portion of said pressure receiving member is attached at least indirectly with a permanent magnet which cooperates with or acts on a Hall-effect sensor and together with said Hall-effect sensor comprises said transducer, the improvement wherein the cross section of said housing in the vicinity of said permanent magnet and in a region between said permanent magnet and said Hall-effect sensor is designed, adjusted or tuned to attain an approximately linear magnet field strength decrease at said Hall-effect sensor and a linear characteristic response curve on motion of said permanent magnet from one near end position to another far end position of said permanent magnet, the improvement defined in claim 1 wherein said cross section of said housing is adjusted by section of materials or the housing wall, the inner surface of said housing wall in the vicinity of said permanent magnet comprising two substantially cylindrical regions, the one in which a moving portion of said pressure receiving member travels being of substantially larger diameter thus forming a stop on which said moving portion of said pressure receiving member is pushed when an overpressure is present in said pressure receiving member.

3. A pressure sensor comprising:

a housing having a housing wall with an inner surface and an outer surface, said outer surface of said housing being substantially cylindrical;

a mechanical pressure receiving member with a moving portion mounted in said housing; and

a mechanical-electrical transducer also mounted in said housing comprising a relatively stationary Hall-effect sensor and a permanent magnet attached at least indirectly to a moving portion of said pressure receiving member, said permanent magnet cooperating with or acting on said Hall Effect sensor, the cross section of said housing and said inner surface in the vicinity of said permanent magnet being substantially cylindrical, said cross section of said inner surface being substantially conical in a region between said permanent magnet and said Hall-effect sensor tapering in the direction of said permanent magnet and being designed, adjusted or tuned to attain an approximately linear magnet field strength increase at said Hall-effect sensor and a linear characteristic response curve on motion of said permanent magnet from one far end position to another near end position.

4. A pressure sensor comprising:

a housing having a housing wall with an inner surface and an outer surface;

a mechanical pressure receiving member with a moving portion mounted in said housing; and

a mechanical-electrical transducer also mounted in said housing comprising a relatively stationary Hall-effect sensor and a permanent magnet attached at least indirectly to said moving portion of said pressure receiving member, said permanent magnet cooperating or acting with said Hall Effect sensor, said inner surface of said housing wall in reference to a near end position adjacent said Hall-effect sensor of said permanent magnet comprising two substantially cylindrical regions, the one in which a moving portion of said pressure receiving member travels being of substantially larger diameter thus forming a stop on which said moving portion of said pressure receiving member is pushed when an overpressure is acting on said pressure receiving member and said inner surface being substantially conical in a region between said Hall-effect sensor and said permanent magnet tapering in the direction of said permanent magnet, said outer surface of said housing wall being substantially cylindrical.