Self-centering magnet assembly for use in a linear travel measurement device

• US 6,536,469 B2
• Filed: 01/16/2001
• Issued: 03/25/2003
• Est. Priority Date: 06/29/1999
• Status: Expired due to Term

• Current Assignee: Fisher Controls International LLC (Emerson Electric Company)
• Original Assignee: Fisher Controls International LLC (Emerson Electric Company)
• Inventors: Hawkins, James C., Woollums, David E., Dilger, John P., Pepperling, Donald P., Dielschneider, Nile K.
• Primary Examiner(s): Michalsky, Gerald A.
• Application Number:
  US09/761,427
• Publication Number:
  US 20020007854A1
• Time in Patent Office: 798 Days
• Field of Search: 137/554
• US Class Current: 137/554
• CPC Class Codes: G01F 1/363 with electrical or electro-mechanical indication G01F1/37 and G01F1/38 take precedence
• CPC Class Codes: G01F 1/383 with electrical or electro-mechanical indication
• CPC Class Codes: G01F 1/40 Details of construction of the flow constriction devices
• CPC Class Codes: G01F 1/42 Orifices or nozzles
• CPC Class Codes: G05D 16/2053 the plurality of throttling means comprising only a first throttling means acting on a higher pressure and a second throttling means acting on a lower pressure, e.g. the atmosphere
• CPC Class Codes: G05D 16/2095 using membranes within the main valve
• CPC Class Codes: Y10T 137/8242 Electrical

Abstract

A magnet assembly is disclosed for use with a magnetic flux sensor to provide a position sensor adapted to detect a position of a moveable member. The magnet assembly comprises a magnet housing defining an inner surface. A magnet is provided that is sized for insertion into the magnet housing and adapted for movement with the moveable member, the magnet having a north pole and a south pole, wherein the magnet generates a magnetic flux. A centering ring is positioned between the magnet and the magnet housing, the centering ring including a biased wall acting to center the magnet in the magnet housing.

Claims

1. A pressure regulator comprising:

a main housing having an inlet and an outlet, a fluid flow path being defined between the inlet and the outlet;

a throttling element moveable in the fluid flow path; and

a throttling element position sensor including;

a magnet housing supported in fixed relation to the main housing and defining an inner surface;

a magnet sized for insertion into the magnet housing and adapted for movement with the throttling element, the magnet having a north pole and a south pole, wherein the magnet generates a magnetic flux;

a centering ring positioned between the magnet and the magnet housing, the centering ring including a biased wall acting to center the magnet in the magnet housing; and

a magnetic field sensor positioned to detect the magnet flux.

2. The regulator of claim 1, in which the centering ring comprises a resilient member and a rigid member, the rigid member defining the biased wall.

3. The regulator of claim 2, in which the resilient member comprises a rubber O-ring.

4. The regulator of claim 2, in which the resilient member comprises an annular spring.

5. The regulator of claim 2, in which the rigid member comprises a plastic ring.

6. The regulator of claim 2, in which the centering ring is supported for movement with the magnet, and in which the resilient member comprises an inner ring and the rigid member comprises an outer ring, the outer ring having an outer wall defining the biased wall, the outer wall being biased outwardly to engage the inner surface of the magnet housing.

7. The regulator of claim 6, further comprising a shuttle having a central bore sized to receive the magnet and an outer surface sized for insertion into the magnet housing, the outer surface defining a groove sized to receive an inner portion of the centering ring.

8. The regulator of claim 7, further comprising a flux-shaping pole piece on each of the north and south poles of the magnet, wherein the shuttle includes two end recesses sized to receive the flux-shaping pole pieces.

9. The regulator of claim 2, in which the centering ring is fixed relative to the magnet housing, wherein the resilient member comprises an outer ring and the rigid member comprises an inner ring, the inner ring having an inner wall defining the biased wall, wherein the outer ring inwardly biases the inner wall.

10. The regulator of claim 9, further comprising a shuttle having a central bore sized to receive the magnet and an outer surface sized for insertion into the magnet housing, the magnet housing inner surface defining a groove sized to receive an outer portion of the centering ring, wherein the inner wall engages the shuttle outer surface.

11. The regulator of claim 10, further comprising a flux-shaping pole piece on each of the north and south poles of the magnet, wherein the shuttle includes two end recesses sized to receive the flux-shaping pole pieces.

12. The regulator of claim 1, further comprising a flux-shaping pole piece on each of the north and south poles of the magnet.

13. The regulator of claim 1, further comprising a second centering ring positioned between the magnet and the magnet housing, the second centering ring including a biased wall acting to center the magnet in the magnet housing.

14. The regulator of claim 1, further comprising a travel indicator connected at one end to the throttling element and at an opposite end to the magnet.