ARMATURE AND SOLENOID ASSEMBLY
TECHNICAL FIELD
The present invention relates to an armature for solenoid devices.
BACKGROUND
It is desirable to attain both high force and a flat force in connection with the -
displacement curve provided by a linear solenoid. It is also desirable to be able to provide a high
force for a full stroke of a proportional solenoid.
SUMMARY
An armature for a solenoid assembly is disclosed. The armature includes a first
portion, a second portion, and a fin. The first portion has a first axial length and a first diameter,
and the first portion is configured for operative connection with a pole piece. The second portion
has a second axial length and a second diameter that is larger than the first diameter. The fin
extends radially from the second portion and has an axial length that is less than the axial length
of the second portion.
In connection with embodiments of the invention, the design of an armature
assembly may be such that, among other things, the armature interacts with the housing to
produce a force when the armature is far from a pole piece, but decreases as the armature
approaches the pole piece. The assembly may be configured to provide a "canceling" of forces
at the associated pole piece, thereby effectively providing a substantially flat force stroke curve.
A solenoid assembly is also disclosed.
BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of the invention will now be described, by way of example, with
reference to the accompanying drawings, wherein:
FIGS. 1 and 2 are cross-sectional views of assemblies for a magnetic solenoid
according to embodiments of the invention; and
FIG. 3 is an enlarged cross-sectional view of III shown in FIG. 2.
DETAILED DESCRIPTION
Reference will now be made in detail to embodiments of the present invention,
examples of which are described herein and illustrated in the accompanying drawings. While the
invention will be described in conjunction with embodiments, it will be understood that they are
not intended to limit the invention to these embodiments. On the contrary, the invention is
intended to cover alternatives, modifications and equivalents, which may be included within the
spirit and scope of the invention as defined by the appended claims.
Different embodiments of solenoid assemblies 10 according to embodiments of the
invention are generally shown in FIGS. 1 and 2. In the illustrated embodiments, the solenoid
assemblies 10 are shown as part of larger valve assemblies. The illustrated solenoid assemblies
each include a coil 12, a pole piece 14, an operating rod 16, and an armature 18. A centerline for
each assembly is generally designated as CL. A portion of a valve body is generally designated
as element 20. However, one of skill in the art will recognize that the invention is not limited to
a valve body 20 of the types shown, and other forms and configurations of valve bodies may be
employed without departing from the teachings of the invention.
FIG. 3 is an enlarged view of area HI in FIG. 2 that generally illustrates a portion of
an armature 18. In an embodiment, armature 18 is substantially symmetrical about the
associated centeriine CL. Armature 18 includes a first portion 22, a second portion 24; and a fin
26 that extends radially from the second portion. Armature 18 may be comprised of a magnetic
material. Armature 18 may, for example and without limitation, be comprised of a magnetic
steel.
First portion 22 includes a first axial length AL1 and a first diameter D1. As
generally illustrated in FIGS. 1-3, first portion 22 may be configured for operative connection
with a pole piece 14. Second portion 24 includes a second axial length AL2 and a second
diameter D2, the second diameter D2 being larger than the first diameter D1. In an embodiment,
fin 26 has an axial length AL3 that is less than the axial length of the second portion AL2.
Moreover, the first portion 22, second portion 24 and fin 26 may be integrally formed.
In an embodiment, the first axial length AL1 is longer than the second axial length
AL2. As generally illustrated in the figures, first portion 22 may include a reduced diameter
portion 28 that is configured to interact with an end (generally identified as 30) of a pole piece
14. The end 30 of the pole piece 14 may include an extension 32 that interacts with armature 18.
For embodiments of the invention, the second diameter D2 of armature 18 may be configured to
be at least twice the first diameter D1.
The fins 26 illustrated in FIGS. 1-3 have, in cross-section, a substantially
rectangular shape. However, those of skill in the art will recognize and understand that fin 26 is
not limited to the forms illustrated, and rather may take the form of a number of shapes and
configurations. It is noted that in an embodiment, the axial length AL3 of fin may be less than
one-half the axial length of the second portion AL2. Also, for some embodiments, the radial
length Lrf of fin 26 may be less than the largest radial length Lr1 of first portion 22. As
generally shown in FIG. 3, fin 26 may also be axially offset an axial distance AL4 from a first
endpoint 34 of second portion 24, and/or may be axially offset an axial distance AL5 from a
second endpoint 36 of second portion 24.
As generally illustrated in the Figures, assembly 10 includes a housing 40. Housing
40 may be comprised of some amount of plastic material to the extent that no magnetic effect is
necessary. Housing 40 may further include an extension 42, such as a step, that extends radially
inwardly from an inner wall of the housing and interacts with fin 26. The interaction between the
extension 42 and the fin 26 typically takes the form of an electromagnetic communication.
Extension 42 is generally positioned so that flux will not bypass the extension.
Viewed in cross-section, extension 42 may have a substantially square or-
rectangular shape. However, additional and/or modified shapes may be employed by those of
skill in the art and are within the teachings of the present invention. With further reference to
FIG. 3, extension 42 is shown generally having an axial length AL6 and a radial length Le. In an
embodiment, assembly 10 may be configured so that the radial length Lrf of the fin 26 is greater
than the radial length LE of the extension 42; and/or the axial length AL6 of the fin 26 is less than
the radial length Lrf of the fin 26. Additionally, embodiments of the assembly 10 may provide
for configurations in which the axial length AL6 of the extension is less than the radial length Le
of the extension, and/or the axial length of the fin AL3 is less than the radial length of the fin
Lrf.
In operation of the assembly, a gap is at times provided between the armature 18
and housing 40. In an embodiment, extension 42 is configured to be longer radially and/or
axially than the greatest operational gap permitted between fin 26 and the extension 42. As such,
the assembly may be configured so that, through the full permitted or operational range of
motion of armature 18, the shortest flux path from armature 18 to housing 40 will be through
extension 42. With such configurations, the electromagnetic force on fin 26 may by increased
when armature 18 is farthest from pole piece 14. Then, as armature 18 moves toward pole piece
14, fin 26 will be in closer communication with extension 42, and an associated flux is permitted
to flow in the radial direction - as opposed to creating an axial force. Such configurations can
permit the forces associated with pole piece 14 and armature 18 to effectively "balance out," i.e.,
offset one another, so that the net resulting force is substantially constant. In practice, the
extension 42 and fin 26 can be configured so that if a current supplied to the assembly 10 is
substantially constant, the associated electromagnetic force will be substantially constant as
armature 18 moves relative to pole piece 14. This can be advantageously for a number of
applications, including those in which a high force is applied to the full stroke of a proportional
solenoid and there is a desire for the associated current to be reliably stable throughout the
stroke.
The foregoing descriptions of specific embodiments of the present invention have
been presented for purposes of illustration and description. They are not intended to be
exhaustive or to limit the invention to the precise forms disclosed, and various modifications and
variations are possible in light of the above teaching. The embodiments were chosen and
described in order to explain the principles of the invention and its practical application, to
thereby enable others skilled in the art to utilize the invention and various embodiments with
various modifications as are suited to the particular use contemplated. It is intended that the
scope of the invention be defined by the claims appended hereto and their equivalents.
We Claim :
1. An armature for a solenoid, the armature comprising:
a first portion having a first axial length and a first diameter, the first portion configured
for operative connection with a pole piece;
a second portion having a second axial length and a second diameter, the second diameter
being larger than the first diameter; and
a fin that extends radially from the second portion, the fin having an axial length that is
less than the axial length of the second portion.
2. The armature of claim 1, wherein the first portion, second portion, and fin are integrally
formed.
3. The armature of claim 1, wherein the armature is comprised of a magnetic material.
4. The armature of claim 3, wherein the magnetic material includes magnetic steel.
5. The armature of claim 1, wherein the first axial length is longer than the second axial
length.
6. The armature of claim 5, wherein the first portion include a reduced diameter portion
configured to interact with an end of the pole piece.
7. The armature of claim 1, wherein the second diameter is at least twice the first diameter.
8. The armature of claim 1, wherein the axial length of the fin is less than one-half the axial
length of the second portion.
9. The armature of claim 1, wherein the radial length of the fin is less than the radial length
of the radial length of the first portion.
10. The armature of claim 1, wherein the fin is axially offset a distance from at least one
endpoint of the second portion.
11. The armature of claim 1, wherein, in cross-section, the fin has a substantially rectangular
shape.
12. A solenoid assembly, comprising:
a pole piece;
an armature, including a first portion, a second portion, and a fin that extends radially
outwardly from the second portion; and
a housing that includes an extension for electromagnetic communication with the fin.
13. The assembly of claim 12, wherein the fin has a radial length, the extension has a radial
length, and the radial length of the fin is greater than the radial length of the extension.
14. The assembly of claim 12, wherein the fin has an axial length and a radial length, and the
axial length of the fin is less than the radial length of the fin.
15. The assembly of claim 12, wherein the extension has an axial length and a radial length,
and the axial length of the extension is less than the radial length of the extension.
16. The assembly of claim 15, wherein the fin has an axial length and a radial length, and the
axial length of the fin is less than the radial length of the fin.
17. The assembly of claim 12, wherein a gap is provided between the armature and the
housing, and the housing extension is configured to be longer, radially or axially, than the
greatest gap permitted between the fin and the extension.
18. The assembly of claim 17, wherein, through the full permitted range of motion of the
armature, the shortest flux path from the armature to the housing is through the housing
extension.
19. The assembly of claim 12, wherein, in cross-section, the extension has a substantially
square or rectangular shape.
20. The assembly of claim 12, wherein as the electromagnetic force on the fin is increased
when the armature is farther from the pole piece.
21. The assembly of claim 12, wherein as the armature moves toward the pole piece, the fin
and extension are in closer communication, and an associated flux is permitted to flow in the
radial direction.
22. The assembly of claim 12, wherein the assembly is configured so that the forces
associated with the pole piece and the armature substantially balance so that the net force is
substantially constant.
23. The assembly of claim 12, wherein the extension and fin are configured such that if a
current supplied to the assembly is substantially constant, the associated electromagnetic force is
substantially constant as the armature moves relative to the pole piece.
24. The assembly of claim 12, wherein the assembly includes a magnetic coil.

An armature 18 for a solenoid assembly 10 is disclosed.
The armature includes a first portion 22, a second
portion 24, and a fin 26. The first portion has a first
axial length AL1 and a first diameter D1, and the first
portion is configured for operative connection with a
pole piece 14. The second portion has a second axial
length AL2 and a second diameter D2 that is larger than
the first diameter. The fin 24 extends radially from
the second portion 22 and has an axial length AL3 that
is less than the axial length AL2 of the second
portion. A solenoid assembly is also disclosed.