Proportional electropneumatic solenoid-controlled valve

• US 5,301,921 A
• Filed: 08/31/1990
• Issued: 04/12/1994
• Est. Priority Date: 06/02/1989
• Status: Expired due to Term

• Current Assignee: Puritan Bennett Corp. (Medtronic Plc)
• Original Assignee: Puritan Bennett Corp. (Medtronic Plc)
• Inventors: Kumar, Viraraghavan S.
• Primary Examiner(s): Rosenthal, Arnold
• Application Number:
  US07/575,943
• Time in Patent Office: 1,320 Days
• Field of Search: 251/129.08, 251/129.07, 335/258, 335/262, 335/269, 335/273, 335/236
• US Class Current: 251/129.08
• 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 magnetic 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, 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 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;

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 second gap for a variation in said second gap over a prescribed range; and

a fluid valve assembly having an inlet port, an outlet port, and valve means, coupled between said inlet port and said outlet port, and being coupled to said armature assembly, for controlling fluid continuity between said inlet port and said outlet port in accordance with the movement of said armature assembly in response to the application of electrical current to said electromagnetic coil.

2. A solenoid device according to claim 1, wherein said valve means comprises a chamber to which said inlet port and said outlet port are coupled, a poppet attached to said armature assembly, and a tube member, a first end of which extends from said chamber toward said outlet port, and a second end of which is arranged in proximity of said poppet so as to be closed by said poppet in response to said poppet being urged against said tube member by movement of said armature assembly in a first axial direction and so as to be opened by said poppet in response to said poppet being urged away from said tube by movement of said armature in a second axial direction.

3. A solenoid device according to claim 2, wherein said valve means further includes means for causing said tube to be aligned with said poppet so that the second end of said tube is sealingly engaged by said poppet when said poppet is urged against said second end of said tube.

4. A solenoid device according to claim 3, wherein said tube aligning means comprises means for fixedly establishing the condition of alignment of said tube with respect to said poppet in response to an initial urging of said poppet against said second end of said tube.

5. A rectilinear motion proportional solenoid device comprising:

a housing, containing an electromagnetic coil which has a longitudinal axis and a bore coaxial therewith, said coil 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 and through which the flux path of said magnetic field passes;

a movable armature assembly of magnetic material through which the flux path of said magnetic field passes;

suspension springs, at least one of which is disposed adjacent to one end of said bore, which support 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 within said bore between a second portion of said armature assembly and a first portion of said housing; and

wherein

said movable armature and said magnetic pole piece are configured to cause 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, and to divert 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 gap.

6. A solenoid device according to claim 5, wherein said magnetic pole piece 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.

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

8. A solenoid device according to claim 7, 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.

9. A solenoid device according to claim 5, 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 said radial gap.

10. A solenoid device according to claim 9, 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 supporting said armature assembly for axial displacement within said member of non-magnetic material and said first cavity.

11. A solenoid device according to claim 5, wherein said magnetic pole piece 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 means adjacent to said axial gap.

12. A solenoid device according to claim 5, further including adjustable spring bias means, coupled with said magnetic pole piece, for imparting a controllable axial force to said armature assembly.

13. A solenoid device according to claim 5, further including a fluid valve assembly having an inlet port, an outlet port, and valve means, coupled between said inlet port and said outlet port, and being coupled to said armature assembly, for controlling fluid continuity between said inlet port and said outlet port in accordance with the movement of said armature assembly in response to the application of electrical current to said electromagnetic coil.

14. 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 through which said flux path passes, said movable armature assembly being supported for movement within the bore of said coil along a longitudinal axis thereof by a pair of suspension springs, at least one of said suspension springs being disposed adjacent to one end of said longitudinal bore, an axial gap formed within said longitudinal bore between one end of said pole piece and said armature, a radial air gap being formed within said longitudinal bore 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.

15. A rectilinear motion proportional solenoid assembly according to claim 14, wherein one of said suspension springs is disposed outside of said longitudinal bore.

16. A rectilinear motion proportional solenoid assembly according to claim 15, wherein one of said suspension springs is disposed within said longitudinal bore.

17. A rectilinear motion proportional solenoid assembly according to claim 14, wherein one of said suspension springs is disposed within said longitudinal bore.