HIGH POWER DENSITY SOLENOID ACTUATOR

Abstract

A solenoid actuator is provided including, a flux return tube, a pole piece having a pole piece shunt, and an armature assembly having a magnetic portion and a non-magnetic spacer. The solenoid actuator also includes two non-magnetic bearing strips for the armature assembly, wherein one of the bearing strip slides on the flux return tube, and a second bearing strip slides on the pole piece shunt.

Claims

1. A solenoid actuator comprising: a flux return tube; a pole piece including a pole piece shunt with an inside diameter within 0.40 mm of said flux return tube inside diameter and wherein said pole piece shunt and said flux return tube are aligned in an axially separated assembly to have centerlines within 0.05 mm concentricity; an armature assembly, said armature assembly including a soft magnetic portion and a non-magnetic spacer, and two non-magnetic bearing strips connected on said armature assembly, said bearing strips having a thickness of 0.025-0.100 mm, wherein one of said bearing strip slides on said flux return tube, and a second of said bearing strips slides on said pole piece shunt and is connected on said non-magnetic spacer.

2. The solenoid actuator of claim 1 wherein at least one of said bearing strips is made from a polymeric material.

3. The solenoid actuator of claim 1 wherein said second bearing strip is also connected on said magnetic portion of said armature.

4. The solenoid actuator of claim 1 wherein said magnetic portion of said armature assembly does not penetrate said pole piece shunt when said armature assembly is at an extreme position away from said pole piece.

5. The solenoid actuator of claim 1 wherein said armature assembly magnetic portion and said armature assembly non-magnetic spacer have a common outer diameter.

6. The solenoid actuator of claim 1 wherein said second bearing strip has an axial length on said non-magnetic spacer of at least 0.5 mm.

7. The solenoid actuator of claim 1 wherein said non-magnetic spacer has an axial length of at least 0.6 mm.

8. The solenoid actuator of claim 1 wherein said first spacer is connected on an extreme end of said magnetic portion of said armature assembly away from said pole piece.

9. The solenoid actuator of claim 1 wherein said armature assembly magnetic portion if fabricated from a low carbon steel.

10. A solenoid actuator comprising: a flux return tube; a pole piece including a pole piece shunt with an inside diameter within 0.40 mm of said flux return tube inside diameter and wherein said pole piece shunt and said flux return tube are aligned in an axially separated assembly to have centerlines within 0.05 mm concentricity; an armature assembly, said armature assembly including a soft magnetic portion and a non-magnetic spacer, and two non-magnetic polymeric bearing strips connected on said armature assembly, said bearing strips having a thickness of 0.025-0.100 mm, wherein one of said bearing strip slides on said flux return tube, and a second of said bearing strips slides on said pole piece shunt and is connected on said non-magnetic spacer and said armature assembly magnetic portion and wherein said magnetic portion of said armature assembly does not penetrate said pole piece shun when the armature assembly is at an extreme position away from said pole piece.

11. A solenoid actuator comprising: a flux return tube; a pole piece including a pole piece shunt with an inside diameter within 0.40 mm of said flux return tube inside diameter and wherein said pole piece shunt and said flux return tube are aligned in an axially separated assembly by a non-magnetic alignment tube to have centerlines within 0.05 mm concentricity; an armature assembly, said armature assembly including a steel soft magnetic portion and a non-magnetic spacer, and two non-magnetic polymeric bearing strips connected on said armature assembly, said bearing strips having a thickness of 0.025-0.100 mm, wherein one of said bearing strip slides on said flux return tube, and a second of said bearing strips slides on said pole piece shunt and is connected on said non-magnetic spacer and said armature assembly magnetic portion, said non-magnetic spacer having an axial length of at least 0.6 mm and wherein said second bearing strip has an axial length on said non-magnetic spacer of at least 0.5 mm, and wherein said magnetic portion of said armature assembly does not penetrate said pole piece shunt when said armature assembly is at an extreme position away from said pole piece.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

[0014] FIG. 1 is a sectional view of a solenoid actuator prior to the present invention;

[0015] FIG. 2 is a sectional view of another solenoid actuator prior to the present invention;

[0016] FIG. 3 is a sectional view of a solenoid actuator according to the present invention;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.

[0018] Referring to FIG. 3, a solenoid actuator 107 according to the present invention is provided. The solenoid actuator 107 has a flux tube 122 that is magnetically connected to the casing 110. The flux tube 122 is axially separated and aligned through a non-magnetic alignment tube 124 or by some other means with the pole piece 126 shunt. The pole piece shunt 126 has inner diameter 125 within 0.40 mm of an inner diameter 123 of the flux tube 122. The flux tube 122 and the pole piece shunt 126 are aligned to have centerlines between within 0.05 mm concentricity.

[0019] An armature assembly 136 is provided slidably mounted within the flux tube 122 and pole piece shunt 126. The armature assembly 136 has a soft magnetic steel portion 139. On a lower axial face 141 of the armature magnetic portion there is provided a non-magnetic spacer 143. The non-magnetic spacer 143 prevents magnetic latching between the armature and an axial flat 145 of the pole piece 118. The armature magnetic steel portion 139 and non-magnetic spacer 143 may be combined through an adhesive, welding, or sintering process. In an embodiment not shown the non-magnetic spacer can have an inner hub (or outer rim) that extends into (or over) an axial bore (or axial outer groove) of the magnetic portion and is press fitted therein (thereon).

[0020] The armature assembly 136 has upper 138 and lower 140 bearings provided by two non-magnetic bearing strips. The bearing strips 138, 140 are typically fabricated from a non-magnetic composite and or non-magnetic polymeric material. A first bearing strip 138 slides on the flux tube 122 and is typically located at an extreme far end away from the pole piece shunt 126. A second bearing strip 140 is applied to the armature assembly 136 at an end of the armature assembly closest to the pole piece unit 126 as possible. The second non-magnetic composite bearing strip 140 is applied at least partially over the non-magnetic spacer 146. As shown the second bearing strip has a portion 152 that is also joined to the armature assembly magnetic portion 139. It is typically preferable that the armature magnetic portion 139 and non-magnetic spacer 143 have a common outer diameter. The non-magnetic spacer 143 typically has an axial length of 0.6 mm or greater. The portion 159 of the bearing strip 140 connected on the non-magnetic spacer is preferably at least 0.5 mm in axial length. When the armature assembly is at an extreme position away from the pole piece shunt 126 (the armature assembly 136 being displaced slightly upward from its position as shown in FIG. 3) it is preferable that the armature magnetic portion 139 not be axially penetrating of the pole piece shunt 126. At the aforementioned extreme position the portion of the lower bearing strip 154 connected to the non-magnetic spacer 143 provides the bearing for the bearing assembly 136.

[0021] The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.