Proportional electropneumatic solenoid-controlled valve

• US 4,954,799 A
• Filed: 06/02/1989
• Issued: 09/04/1990
• Est. Priority Date: 06/02/1989
• Status: Expired due to Term

• Current Assignee: Puritan-Bennett Corporation 9401 Indian Creek Parkway Overland Park Kansas
• Original Assignee: Puritan Bennett Corp. (Medtronic Plc)
• Inventors: Kumar, Viraraghavan S.
• Primary Examiner(s): Rosenthal, Arnold
• Application Number:
  US07/360,429
• Time in Patent Office: 459 Days
• Field of Search: 251/129.08, 251/129.07, 335/258, 335/262, 335/269, 335/273, 335/236
• US Class Current: 335/236
• CPC Class Codes: H01F 7/13 characterised by pulling-force characteristics

Abstract

A rectilinear motion proportional solenoid assembly includes a cylindrical housing containing an electromagnetic coil having a longitudinal coaxial bore. The housing contains maagnetic material for providing a flux path for the magnetic field produced by the coil. A generally cylindrical magnetic pole piece element is inserted into the bore and a movable armature assembly of magnetic material is supported within the bore for movement along the longitudinal axis of the coil by a pair of thin, flexible suspension springs. One of the springs is located within the bore adjacent to one end of the magnetic pole piece whereat an axial gap between the pole piece and the armature is formed. A second spring is located within the housing within the vicinity of a radial air gap between the armature and the housing. The pole piece contains an auxiliary region adjacent to the axial air gap for shunting a portion of the axially directed magnetic flux, for effectively causing the force imparted to the movable armature by the application of a current to the electromagnetic coil to be substantially constant irrespective of the magnitude of the axial gap for a variation in the axial gap over a prescribed range.

Claims

1. A rectilinear motion proportional solenoid device comprising:

a housing containing an electromagnetic coil, said electromagnetic coil having a longitudinal axis and a bore coaxial therewith, for producing a magnetic field, said housing containing magnetic material for providing a flux path for said magnetic field;

a magnetic pole piece disposed within the bore of said electromagnetic coil;

a movable armature assembly of magnetic material;

suspension spring means within said bore of said electromagnetic coil for supporting said movable armature within said bore adjacent to one end of said magnetic pole piece for axial movement within said electromagnetic coil, so that an axial gap is formed between a first portion of said armature assembly and said magnetic pole piece and a radial gap is formed between a second portion of said armature assembly and a first portion of said housing; and

means for causing the force imparted to said movable armature by the application of a current to said electromagnetic coil to be substantially constant irrespective of the magnitude of said axial gap for a variation in said axial gap over a prescribed range.

2. A solenoid device according to claim 1, wherein said suspension spring means includes a spring member which comprises an outer ring portion, a plurality of annular ring portions spaced apart from said outer ring portion and attached thereto in an cantilever fashion, and an interior portion attached to said annular ring portions said interior portion being attached to said armature assembly and said outer ring portion being fixedly located within said bore.

3. A solenoid device according to claim 1, wherein said substantially constant force causing means comprises means for diverting a portion of the magnetic flux that passes through said armature and said pole piece in the direction of said axis through a low reluctance magnetic path that substantially bypasses said axial air gap.

4. A solenoid device according to claim 3, wherein said magnetic pole piece element includes a first pole piece region spaced apart from said armature assembly by said axial gap and wherein said constant force causing means comprises a second pole piece region adjacent to said axial gap.

5. A solenoid device according to claim 4, wherein said suspension spring means includes a spring member which comprises an outer ring portion, a plurality of annular ring portions spaced apart from said outer ring portion and attached thereto in an cantilever fashion, and an interior portion attached to said annular ring portions, said interior portion being attached to said armature assembly and said outer ring portion being fixedly located within said bore.

6. A solenoid device according to claim 5, wherein said second pole piece region has a varying thickness in the direction of said longitudinal axis.

7. A solenoid device according to claim 6, wherein said second pole piece region is spaced apart from said first pole piece region by a further gap which is transverse to the direction of movement of said armature assembly.

8. A solenoid device according to claim 3, wherein said armature assembly is generally cylindrically configured and said housing comprises a base member having a first generally cylindrically configured cavity in which said armature assembly is supported for axial movement therein, said cavity having a first cylindrical sidewall portion containing magnetic material, corresponding to said first portion of said housing, spaced apart from a first cylindrical portion of said armature assembly so as to define therebetween a said radial gap.

9. A solenoid device according to claim 8, further including a generally cylindrical member of non-magnetic material extending from said first cylindrical sidewall of said first cavity toward and coupled with said magnetic pole piece, and wherein said suspension spring means comprises a pair of suspension springs respectively supported by said member of non-magnetic material and said base member, respectively, and thereby supporting said armature assembly for axial displacement within said member of non-magnetic material and said first cavity.

10. A solenoid device according to claim 9, wherein said magnetic pole piece means includes a first generally cylindrically configured pole piece region spaced apart from an end region of said armature assembly by said axial gap, and a second generally cylindrically configured pole piece region corresponding to said magnetic flux diverting region adjacent to said axial gap.

11. A solenoid device according to claim 8, wherein said armature assembly includes a generally solid cylinder of magnetic material and said suspension spring means comprises a pair of suspension spring members, respectively coupled to axially spaced apart portions of said solid cylinder and retained by said member of non-magnetic material and said housing, respectively.

12. A solenoid device according to claim 11, wherein a suspension spring member comprises an outer ring portion, a plurality of annular ring portions spaced apart from said outer ring portion and attached thereto in a cantilever fashion, and an interior portion attached to said annular ring portions, said interior portion being attached to said generally solid cylinder of magnetic material and said outer ring portion being coupled to one of said member of non-magnetic material and said housing.

13. A solenoid device according to claim 11, further including adjustable spring bias means, coupled with said magnetic pole piece, for imparting a controllable axial force to said armature assembly.

14. A solenoid device according to claim 13, wherein said adjustable spring bias means comprises a compression spring member, means for mechanically coupling said compression spring member to said armature assembly and means, coupled between said compression spring member and said magnetic pole piece, for adjustably compressing said compression spring member and thereby causing said compression spring member to couple said controllable axial force to said armature assembly.

15. A rectilinear motion proportional solenoid device comprising:

a housing, containing an electromagnetic coil having an interior axial bore and producing a magnetic field, said housing including magnetic material for providing a flux path for said magnetic field;

a magnetic pole piece element located within the axial bore of said electromagnetic coil;

a movable armature assembly of magnetic material supported for movement within, and in the direction of, the axial bore of, said electromagnetic coil, so that a first gap, which is transverse to the direction of movement of said armature assembly, is formed between a first portion of said armature assembly and a first portion of said housing, and a second gap, which is parallel to the direction of movement of said armature assembly, is formed between a second portion of sad armature assembly and a first portion of said magnetic pole piece element; and

a pair of suspension spring members, respectively coupled to axially spaced apart portions of said movable armature assembly and one of which is retained within the axial bore of said coil and the other of which is retained by said housing for supporting said armature assembly for axial movement within the axial bore of said electromagnetic coil, each suspension spring member comprising an outer ring portion, a plurality of annular ring portions spaced apart from said outer ring portion and attached thereto in an cantilever fashion, and an interior portion attached to said annular ring portions, the interior portion of one of said pair of suspension spring members being attached to a first portion of said armature assembly and its outer ring portion being supported within said axial bore and the interior portion of the other of said pair of suspension spring members being attached to a second portion of said armature assembly and its outer ring portion being coupled to said housing.

16. A solenoid device according to claim 15, wherein said magnetic pole piece element includes a first pole piece region spaced apart from said armature assembly by said second gap and a second pole piece region adjacent to said second gap for providing a magnetic flux shunt path for diverting magnetic flux between said armature and said pole piece element.

17. A rectilinear motion proportional solenoid assembly comprising a cylindrical housing accommodating an electromagnetic coil having a longitudinal bore, said housing containing magnetic material for providing a flux path for a magnetic field produced. by said coil, a generally cylindrical magnetic pole piece disposed within said bore, a movable armature assembly of magnetic material supported within said bore for movement along a longitudinal axis of the coil by a pair of suspension springs, one of said springs being located within the bore adjacent to one end of said magnetic pole piece whereat an axial gap is formed between said pole piece and said armature, the other of said springs being located within s id housing in the vicinity of a radial air gap formed between said armature and said housing, and wherein said pole piece includes a magnetic flux shunting region adjacent to said axial gap for diverting therefrom a portion of magnetic flux passing along said bore and thereby effectively causing the force imparted to the movable armature by the application of a current to the electromagnetic coil to be substantially constant irrespective of the magnitude of said axial gap for a variation in said axial gap over a prescribed range.

18. A solenoid device according to claim 17, wherein a suspension spring includes a spring member which comprises an outer ring portion, a plurality of annular ring portions spaced apart from said outer ring portion and attached thereto in an cantilever fashion, and an interior portion attached to said annular ring portions, said interior portion being attached to said armature assembly and said outer ring portion being fixedly located within said bore.