Title: Releasable fastener system
Abstract: A releasable fastener system comprises two hook portions. The hook portions each include a support and a plurality of closely spaced upstanding hook elements extending from one side thereof. When the two hook portions are pressed together they interlock to form a releasable engagement. The resulting joint created by the engagement is relatively resistant to shear and pull forces and weak in peel strength forces. The head elements of the hook elements are formed of a material that provides a change in directional orientation of the head elements. In this manner, the directional orientation of the head elements of the hook elements can be remotely changed to provide a reduction or magnification in the shear and/or pull-off forces.
Patent Number: 6,983,517 Issued on 01/10/2006 to Golden, et al.
| Inventors:
|
Golden; Mark A. (Washington, MI);
Ulicny; John C. (Oxford, MI)
|
| Assignee:
|
General Motors Corporation (Detroit, MI)
|
| Appl. No.:
|
305376 |
| Filed:
|
November 26, 2002 |
| Current U.S. Class: |
24/442; 428/100 |
| Current Intern'l Class: |
A44B 18/00 (20060101) |
| Field of Search: |
24/442,446,451,452,450,448,304
428/100
|
References Cited [Referenced By]
U.S. Patent Documents
| 2717437 | Sep., 1955 | DeMestral.
| |
| 2994117 | Aug., 1961 | McMullin.
| |
| 3101517 | Aug., 1963 | Fox et al.
| |
| 3128514 | Apr., 1964 | Parker et al.
| |
| 3138749 | Jun., 1964 | Slibitz.
| |
| 3176364 | Apr., 1965 | Dritz.
| |
| 3292019 | Dec., 1966 | Hsu et al.
| |
| 3365757 | Jan., 1968 | Billarant.
| |
| 3469289 | Sep., 1969 | Whitacre.
| |
| 3490107 | Jan., 1970 | Brumlik.
| |
| 3808648 | May., 1974 | Billarant et al.
| |
| 4169303 | Oct., 1979 | Lemelson.
| |
| 4382243 | May., 1983 | Babitzka et al.
| |
| 4391147 | Jul., 1983 | Krempl et al.
| |
| 4634636 | Jan., 1987 | Yoshino et al.
| |
| 4637944 | Jan., 1987 | Walker.
| |
| 4642254 | Feb., 1987 | Walker.
| |
| 4693921 | Sep., 1987 | Billarant et al.
| |
| 4752537 | Jun., 1988 | Das.
| |
| 4775310 | Oct., 1988 | Fischer.
| |
| 4794028 | Dec., 1988 | Fischer.
| |
| 4931344 | Jun., 1990 | Ogawa et al.
| |
| 5037178 | Aug., 1991 | Stoy et al.
| |
| 5071363 | Dec., 1991 | Reylek et al.
| |
| 5133112 | Jul., 1992 | Gomez-Acevedo.
| |
| 5136201 | Aug., 1992 | Culp.
| |
| 5182484 | Jan., 1993 | Culp.
| |
| 5191166 | Mar., 1993 | Smirlock et al.
| |
| 5212855 | May., 1993 | McGanty.
| |
| 5284330 | Feb., 1994 | Carlson et al.
| |
| 5312456 | May., 1994 | Reed et al.
| |
| 5319257 | Jun., 1994 | McIntyre.
| |
| 5328337 | Jul., 1994 | Kunta.
| |
| 5474227 | Dec., 1995 | Krengel et al.
| |
| 5486676 | Jan., 1996 | Aleshin.
| |
| 5492534 | Feb., 1996 | Athayde et al.
| |
| 5497861 | Mar., 1996 | Brotz.
| |
| 5547049 | Aug., 1996 | Weiss et al.
| |
| 5611122 | Mar., 1997 | Torigoe et al.
| |
| 5656351 | Aug., 1997 | Donaruma.
| |
| 5657516 | Aug., 1997 | Berg et al.
| |
| 5669120 | Sep., 1997 | Wessels et al.
| |
| 5671498 | Sep., 1997 | Martin et al.
| |
| 5712524 | Jan., 1998 | Suga.
| |
| 5725928 | Mar., 1998 | Kenney et al.
| |
| 5797170 | Aug., 1998 | Akeno.
| |
| 5798188 | Aug., 1998 | Mukohyama et al.
| |
| 5814999 | Sep., 1998 | Elie et al.
| |
| 5816587 | Oct., 1998 | Stewart et al.
| |
| 5817380 | Oct., 1998 | Tanaka.
| |
| 5885652 | Mar., 1999 | Abbott et al.
| |
| 5945193 | Aug., 1999 | Pollard et al.
| |
| 5969518 | Oct., 1999 | Merklein et al.
| |
| 5974856 | Nov., 1999 | Elie et al.
| |
| 5979744 | Nov., 1999 | Brigleb.
| |
| 5983467 | Nov., 1999 | Duffy.
| |
| 6029783 | Feb., 2000 | Wirthlin.
| |
| 6086599 | Jul., 2000 | Lee et al.
| |
| 6102912 | Aug., 2000 | Cazin et al.
| |
| 6102933 | Aug., 2000 | Lee et al.
| |
| 6129970 | Oct., 2000 | Kenney et al.
| |
| 6148487 | Nov., 2000 | Billarant.
| |
| 6156842 | Dec., 2000 | Hoenig et al.
| |
| 6203717 | Mar., 2001 | Munoz et al.
| |
| 6257133 | Jul., 2001 | Anderson.
| |
| 6388043 | May., 2002 | Langer et al.
| |
| 6454923 | Sep., 2002 | Dodgson et al.
| |
| 6460230 | Oct., 2002 | Shimamura et al.
| |
| 6502290 | Jan., 2003 | Tseng.
| |
| 6544245 | Apr., 2003 | Neeb et al.
| |
| 6546602 | Apr., 2003 | Eipper et al.
| |
| 6593540 | Jul., 2003 | Baker et al.
| |
| 6598274 | Jul., 2003 | Marmaropoulos.
| |
| 6605795 | Aug., 2003 | Arcella et al.
| |
| 6681849 | Jan., 2004 | Goodson.
| |
| 6740094 | May., 2004 | Maitland et al.
| |
| 6742227 | Jun., 2004 | Ulicny et al.
| |
| 6766566 | Jul., 2004 | Cheng et al.
| |
| 6797914 | Sep., 2004 | Speranza et al.
| |
| 6815873 | Nov., 2004 | Johnson et al.
| |
| 2001/0040819 | Nov., 2001 | Hayashi et al.
| |
| 2002/0007884 | Jan., 2002 | Schuster et al.
| |
| 2002/0050045 | May., 2002 | Chiodo.
| |
| 2002/0062547 | May., 2002 | Chiodo et al.
| |
| 2002/0076520 | Jun., 2002 | Neeb et al.
| |
| 2002/0086152 | Jul., 2002 | Gambino et al.
| |
| 2002/0142119 | Oct., 2002 | Seward et al.
| |
| 2003/0120300 | Jun., 2003 | Porter.
| |
| 2004/0025639 | Feb., 2004 | Shahinpoor et al .
| |
| 2004/0033336 | Feb., 2004 | Schulte.
| |
| 2004/0074061 | Apr., 2004 | Ottaviani et al.
| |
| 2004/0074062 | Apr., 2004 | Stanford et al.
| |
| 2004/0074064 | Apr., 2004 | Powell et al.
| |
| 2004/0074067 | Apr., 2004 | Browne et al.
| |
| 2004/0074068 | Apr., 2004 | Browne et al.
| |
| 2004/0074069 | Apr., 2004 | Browne et al.
| |
| 2004/0074070 | Apr., 2004 | Momoda et al.
| |
| 2004/0074071 | Apr., 2004 | Golden et al.
| |
| 2004/0117955 | Jun., 2004 | Barvosa-Carter et al.
| |
| Foreign Patent Documents |
| 199 56 011 | Jun., 2001 | DE.
| |
| 0385443 | Sep., 1990 | EP.
| |
| 0673709 | Sep., 1995 | EP.
| |
| 401162587 | Jun., 1989 | JP.
| |
| 4-314446 | Apr., 1992 | JP.
| |
| 4266970 | Sep., 1992 | JP.
| |
| 08260748 | Oct., 1996 | JP.
| |
| WO 99/4252/8 | Aug., 1999 | WO.
| |
| WO 00/6263/7 | Oct., 2000 | WO.
| |
| WO 01/8400/2 | Nov., 2001 | WO.
| |
| WO 02/4553/6 | Jun., 2002 | WO.
| |
Primary Examiner: Lavinder; Jack W.
Attorney, Agent or Firm: Marra; Kathryn A.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part of U.S. application Ser. No. 10/273,691
filed Oct. 19, 2002, which is incorporated by reference herein in its entirety.
Claims
The invention claimed is:
1. A releasable fastener system comprising:
a first portion comprising a first support and a plurality of first hook elements
disposed on a surface, wherein each one the first hook elements comprise a head
elements disposed on a shaft;
a second portion comprising a second support and a plurality of second hook elements
disposed on a surface, wherein each one of the second hook elements comprises a
head elements rotatably disposed on a shaft, wherein the head elements comprises
a material adapted to change a directional orientation upon receipt of a magnetic
signal; and
an activation device coupled to the plurality of the second hook elements, the
activation device being operable to selectively provide the magnetic signal to
the head elements of the second hook elements, wherein the magnetic signal effectuates
a change in the directional orientation of the head elements of the second hook
elements to reduce or increase a shear force and/or a pull-off force.
2. The releasable fastener system of claim 1, wherein the magnetic signal comprises
a magnetic field oriented in a direction to effectuate a change in the directional
orientation of the head elements of the second hook elements by rotating the head
elements of the second hook elements substantially in an x-plane with respect to
the hook element support.
3. The releasable fastener system of claim 1, wherein the first and second head
elements comprise a J-shape, an L-shape, a multi-tined anchor shape, or a T-shape.
4. The releasable fastener system of claim 1, wherein the first hook elements
engage with the second hook elements when the first portion is pressed into face-to-face
engagement with the second portion.
5. The releasable fastener system of claim 1, wherein the magnetic signal effectuates
a change in position of the first and second head elements, wherein the second
head elements are substantially parallel to the first head elements, to reduce
a shear force and/or a pull-off force.
6. The releasable fastener system of claim 1, wherein the magnetic signal effectuates
a change in position of the first and second head elements, wherein the second
head elements are substantially perpendicular to the first head elements forming
an interlocking system to increase a shear force and/or a pull-off force.
7. The releasable fastener system of claim 1, wherein the second head elements
comprise a magnetic material, a magnetorheological fluid, a magnetorheological
elastomer, or combinations comprising at least one of the foregoing materials.
8. The releasable fastener system of claim 1, wherein the second head elements
comprise ferromagnetic or paramagnetic particles dispersed in a carrier fluid,
wherein the particles are selected from the group consisting of iron, iron alloys,
iron oxides, iron nitride, iron carbide, carbonyl iron, nickel, cobalt, chromium
dioxide, stainless steel, silicon steel, and combinations comprising at least one
of the foregoing; and
wherein the carrier fluid is selected from the group consisting of silicone oils,
mineral oils, paraffin oils, silicone copolymers, white oils, hydraulic oils, transformer
oils, halogenated paraffins, perfluorinated polyethers and fluorinated hydrocarbons,
diesters, polyoxyalkylenes, fluorinated silicones, cyanoalkyl siloxanes, glycols,
synthetic hydrocarbon oils, and combinations comprising at least one of the foregoing fluids.
9. The releasable fastener system of claim 1, wherein the second head elements
comprise ferromagnetic or paramagnetic particles in poly-alpha-olefins, natural
rubber, silicone, polybutadiene, polyethylene, polyisoprene, or combinations comprising
at least one of the foregoing polymeric materials.
10. The releasable fastener system of claim 1, wherein the second head elements
comprise a magnetic material based on iron, nickel, cobalt, alloys of the foregoing,
or combinations comprising at least one of the foregoing.
11. The releasable fastener system of claim 1, wherein the first head elements
comprise a material adapted to change a directional orientation of the head elements
of the first hook elements upon receipt of a magnetic signal.
12. The releasable fastener system of claim 11, wherein the magnetic signal comprises
a magnetic field oriented in a direction to effectuate a change in the directional
orientation of the head elements of the first and second hook elements by rotating
the head elements of the first and second hook elements substantially in an x-plane
with respect to the first and second supports.
13. The releasable fastener system of claim 12, wherein the change in the directional
orientation of the first and second head elements reduces a shear force and/or
pull-off force.
14. The releasable fastener system of claim 12, wherein the change in the directional
orientation of the first and second head elements increases a shear force and/or
pull-off force.
15. A process for operating a releasable fastener system, the process comprising:
contacting a first portion to a second portion to form a releasable engagement,
wherein the first portion comprises a first support and a plurality of first
hook elements disposed on a surface, wherein each one of the first hook elements
comprise a head element disposed on a shaft; and
a second portion comprising a second support and a plurality of second hook elements
disposed on a surface, wherein each one of the second hook elements comprise a
head element rotatably disposed on a shaft, wherein the head elements comprises
a material adapted to change a directional orientation to the head elements upon
receipt of a magnetic signal;
maintaining constant shear and pull-off forces in the releasable engagement;
selectively introducing the magnetic signal to the second hook elements, wherein
the magnetic signal is effective to change the directional orientation of the head
elements; and
reducing shear and/or pull-off forces in the releasable engagement.
16. The process according to claim 15, wherein the second head elements comprise
a magnetic material, a magnetorheological fluid, a magnetorheological elastomer,
or combinations comprising at least one of the foregoing materials.
17. The process according to claim 15, wherein the magnetic signal comprises
a magnetic field oriented in a direction to effectuate a change in the directional
orientation to the second head elements by rotating the second head elements substantially
in an x-plane with respect to the second support.
18. The process according to claim 15, wherein the first head elements comprise
a material adapted to change a directional orientation of the first head elements
upon receipt of a magnetic signal.
19. The process according to claim 15, wherein the magnetic signal comprises
a magnetic field oriented in a direction to effectuate a change in the directional
orientation of the first and second head elements by rotating the first and second
head elements substantially in an x-plane with respect to the first and second supports.
20. A hook portion for a releasable fastener system comprising:
a support; and
a plurality of hook elements disposed on a surface, wherein each one of the hook
elements comprise a head element rotatably disposed on a shaft, wherein the head
elements comprises a material adapted to change a directional orientation to the
head elements upon receipt of a magnetic signal, wherein the magnetic signal is
a magnetic field oriented in a direction to effectuate a change in the directional
orientation to the head elements by rotation of the head elements substantially
in an x-plane with respect to the support, and wherein the head elements comprise
a magnetic material, a magnetorheological fluid, a magnetorheological elastomer,
or combinations comprising at least one of the foregoing materials.
21. The hook portion according to claim 20, wherein the support comprises a metal,
a plastic, a fabric, or a combination comprising at least one of the foregoing materials.
22. A process for operating a releasable fastener system, the process comprising:
providing a first portion comprising a first support and a plurality of first
hook elements disposed on a surface, wherein each one of the first hook elements
comprise a head elements disposed on a shaft;
applying a magnetic signal to a second portion comprising a second support and
a plurality of second hook elements disposed on the support, wherein each one of
the second hook elements comprises a head elements rotatably disposed on a shaft,
and wherein the second head elements comprise a material adapted to change a directional
orientation upon receipt of a magnetic signal;
contacting the first portion with the second portion; and
discontinuing the magnetic signal to cause the first hook elements and the second
hook elements to interlock.
23. A releasable fastener system comprising:
a first portion comprising a first support and a plurality of first hook elements
disposed on a surface, wherein each one of the first hook elements comprises a
head elements rotatably disposed on a shaft; and
a second portion comprising a second support and a plurality of second hook elements
disposed on a surface, wherein each one of the second hook elements comprises a
head element rotatably disposed on a shaft, wherein the second head elements comprise
a material adapted to change a directional orientation upon receipt of a magnetic
signal, and wherein the magnetic signal comprises a magnetic field oriented in
a direction to effectuate a change in the directional orientation of the first
and second head elements by rotating the first and second head elements substantially
in an x-plane with respect to the first and second supports; and
means for changing the directional orientation of the second head elements to
reduce a shear force and/or a pull-off force of engaged first hook elements and
second hook elements.
24. The releasable fastener system according to claim 23, wherein the first support
and the second support are fabricated from an inflexible material.
25. The releasable fastener system according to claim 23, wherein the first head
elements comprises a material adapted to change a directional orientation upon
receipt of a magnetic signal.
26. A hook portion for a releasable fastener system comprising;
a support; and
a plurality of hook elements disposed on a surface, wherein each one of the hook
elements comprise a head element rotatably disposed on a shaft, wherein the head
elements comprise a material adapted to change a directional orientation upon receipt
of a magnetic signal, and wherein the magnetic signal is a magnetic field oriented
in a direction to effectuate a change in the directional orientation by rotation
substantially in an x-plane with respect to the support.
27. The hook portion according to claim 26, wherein the head elements comprise
a magnetic material, a magnetorheological fluid, a magnetorheological elastomer,
or combinations comprising at least one of the foregoing materials.
28. The hook portion according to claim 26, wherein the support comprises a metal,
a plastic, a fabric, or a combination comprising at least one of the foregoing materials.
Description
BACKGROUND
This disclosure relates to releasable attachment devices of the type used to
fasten, retain, or latch together components of an apparatus or a structure that
are to be separated or released under controlled conditions.
Hook and loop type separable fasteners are well known and are used to join two
members detachably to each other. These types of fasteners generally have two components
disposed on opposing member surfaces. One component typically includes a plurality
of resilient hooks while the other component typically includes a plurality of
loops. When the two components are pressed together they interlock to form a releasable
engagement. A variation on the hook and loop motif is the hook and hook motif.
The resulting joint created by the engagement is relatively resistant to shear
and pull forces, and weak in peel strength forces. As such, peeling one component
from the other component can be used to separate the components with a minimal
applied force. As used herein, the term "shear" refers to an action or stress resulting
from applied forces that causes or tends to cause two contiguous parts of a body
to slide relatively to each other in a direction parallel to their plane of contact.
The term "pull force" refers to an action or stress resulting from applied forces
that causes or tends to cause two contiguous parts of a body to move relative to
each other in a direction perpendicular to their plane of contact.
Magnetorheological (MR) fluids and elastomers are known as "smart"
materials whose rheological properties can rapidly change upon application of a
magnetic field. MR fluids are suspensions of micrometer-sized, magnetically polarizable
particles in oil or other liquids. As shown in FIG. 1, when a MR fluid
2
is exposed to a magnetic field, the normally randomly oriented particles
4
within the fluid
6 form chains of particles in the direction of the magnetic
field lines. The particle chains increase the apparent viscosity (flow resistance)
of the fluid. MR elastomers are suspensions of micrometer-sized, magnetically polarizable
particles in a thermoset elastic polymer or rubber. The stiffness of the elastomer
structure is accomplished by changing the shear and compression/tension moduli
by varying the strength of the applied magnetic field. The MR fluids and elastomers
typically develop structure when exposed to a magnetic field in as little as a
few milliseconds. Discontinuing the exposure of the MR fluid or elastomers to the
magnetic field reverses the process and the fluid returns to a lower viscosity
state or the elastomer returns to its lower modulus state. MR fluids enclosed in
structural elements have been disclosed in U.S. Pat. No. 5,547,049.
BRIEF SUMMARY
Disclosed herein is a releasable fastener system that provides for a controlled
release or separation of a joint in a shear and/or pull-off direction. A releasable
fastener system comprises a first portion comprising a first support and a plurality
of first hook elements disposed on a surface, wherein the first hook elements comprise
head elements at ends of the first hook elements; a second portion comprising a
second support and a plurality of second hook elements disposed on a surface, wherein
the second hook elements comprise head elements at ends of the second hook elements,
wherein the head elements of the second hook elements comprise a material adapted
to change a directional orientation of the head elements of the second hook elements
upon receipt of a magnetic signal; and an activation device coupled to the plurality
of the second hook elements, the activation device being operable to selectively
provide the magnetic signal to the head elements of the second hook elements, wherein
the magnetic signal effectuates a change in the directional orientation of the
head elements of the second hook elements to reduce or increase a shear force and/or
a pull-off force.
In another embodiment the first hook elements also comprise a material adapted
to change a directional orientation of the head elements of the first hook elements
upon receipt of a magnetic signal.
A process for operating a releasable fastener system, the process comprises contacting
a first portion to a second portion to form a releasable engagement, wherein the
first portion comprises a first support and a plurality of first hook elements
disposed on a surface, wherein the first hook elements comprise head elements at
ends of the first hook elements; and a second portion comprising a second support
and a plurality of second hook elements disposed on a surface, wherein the second
hook elements comprise head elements at ends of the second hook elements, wherein
the head elements of the second hook elements comprise a material adapted to change
a directional orientation of the head elements of the second hook elements upon
receipt of a magnetic signal; maintaining constant shear and pull-off forces in
the releasable engagement; selectively introducing the magnetic signal to the head
elements of the second hook elements, wherein the magnetic signal is effective
to change the directional orientation of the head elements of the second hook elements;
and reducing shear and/or pull-off forces in the releasable engagement.
A hook portion for a releasable fastener system comprises a support; and a plurality
of hook elements disposed on a surface, wherein the hook elements comprise head
elements at ends of the hook elements, and wherein the head elements comprise a
material adapted to change a directional orientation of the head elements upon
receipt of a magnetic signal.
The above described and other features are exemplified by the following figures
and detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
Referring now to the figures, which are exemplary embodiments and wherein
the like elements are numbered alike:
FIG. 1 is a schematic of a magnetorheological fluid;
FIG. 2 is a cross sectional view of a releasable fastening system;
FIG. 3 is a schematic of magnetic swivel hooks in a locked position;
FIG. 4 is a schematic of magnetic swivel hooks in an unlocked position;
FIG. 5 is a schematic of an overhead view of magnetic swivel hooks in a locked position;
FIG. 6 is a schematic of an overhead view of magnetic swivel hooks in an unlocked position;
FIG. 7 is a schematic of a magnetic swivel hook, with an interior view of the
hook's head; and
FIG. 8 is a schematic of a magnetic swivel hook.
DETAILED DESCRIPTION
As shown in FIG. 2, a releasable fastener system, generally indicated as
10,
comprises a first hook portion
12 and a second hook portion
14. The
first hook portion
12 includes a support
16 and a plurality of closely
spaced upstanding first hook elements
18 extending from one side thereof.
At the ends of the first hook elements are first head elements
17. The second
hook portion
14 includes a support
20 and a plurality of closely
spaced upstanding second hook elements
22 extending from one side thereof.
At the ends of the second hook elements are second head elements
21. The
second head elements
21 are formed of a material that provide a directional
orientation capability to the second head elements
21, as will be described
in greater detail. Preferably, the second head elements are fabricated from materials
that are resilient and flexible in addition to providing a directional orientation
capability. Coupled to and in operative communication with the second head elements
21 is an activation device
24. The activation device
24, on
demand, provides an activation signal to the second head elements
21 to
change the directional orientation of the second head elements
21. The activation
signal provided by activation device
24 for changing the directional orientation
of the second head elements
21 is a magnetic signal in the form of a magnetic
field. The change in directional orientation generally remains for the duration
of the applied activation signal. Upon discontinuation of the activation signal,
the second head elements
21 revert substantially to a relaxed or unpowered
orientation, and as such, are free to swivel about the central axis of the support.
The illustrated releasable fastener system
10 is exemplary only and is not
intended to be limited to any particular shape, size, configuration, number or
shape of second head elements
21, second hook elements
22, first
head elements
17, first hook elements
18, or the like.
During engagement, the two portions
12 and
14 are pressed together
to create a joint that is relatively strong in shear and pull-off directions, and
weak in a peel direction. For example, when the two portions
12 and
14
are pressed into face-to-face engagement, the first head elements
17 become
engaged with the second head elements
21 and the close spacing of the hook
elements
18 and
22 resists substantial lateral movement when subjected
to shearing forces in the plane of engagement. Similarly, when the engaged joint
is subjected to a force perpendicular to this plane, (i.e., pull-off forces), the
interlocked first head elements
17 and second head elements
21 resist
substantial separation of the two portions
12 and
14. However, when
the second head elements
21 are subjected to a peeling force, the second
head elements
21 and the first head elements
17 can become disengaged
from one another. It should be noted that separating the two portions
12
and
14 using the peeling force generally requires that one or both of the
supports forming the hook portions be flexible.
To reduce shear and pull-off forces resulting from the engagement, the directional
orientation of the second head elements
21 is altered upon receipt of the
activation signal from the activation device
24 to provide a remote releasing
mechanism of the engaged joint. An exemplary directional orientation change of
second head elements
21 is from an orientation substantially perpendicular
to the first head elements
17 to an orientation substantially parallel to
the first head elements
17. As a result of changing the directional orientation
of the second head elements
21, a marked reduction in shear and pull-off
forces is observed, thereby allowing the joint to separate in directions normally
associated with pull-off and shear. That is, the change in directional orientation
reduces the shearing forces in the plane of engagement, and reduces the pull-off
forces perpendicular to the plane of engagement. In effect, the second head elements
swivel so that they align with the first head elements allowing for the joint to
separate with less force. For example, as shown in FIGS. 3 and 5, the second hook
elements
22 have second head elements
21 oriented substantially perpendicular
to the first head elements
17. In FIGS. 4 and 6 the directional orientation
of the second head elements
21 are reoriented, upon receiving an activation
signal from the activation device
24, to a substantially parallel orientation
to the first head elements
17. The substantially parallel orientation relative
to the orientation of first head elements provides a joint with marked reductions
in shear and pull-off forces.
In another embodiment the receipt of an activation signal from activation device
24 increases shear and pull-off forces of the engaged joint. Upon receipt
of the activation signal, the second head elements
21 can be oriented to
maintain a substantially perpendicular orientation to the first head elements
17.
During the time the activation signal is on, the peeling force required to separate
portions
12 and
14 is increased by the maintenance of the interlocking
system of the first and second head elements
17 and
21.
The hook elements
22 may be formed integrally with support
20,
or more preferably, may be disposed on the support
20. In practice, the
spacing between adjacent second hook elements
22 and second head elements
21 is an amount effective to provide sufficient shear and pull-off resistance
desired for the particular application during engagement with first hook elements
18 and first head elements
17. Depending on the desired application,
the amount of shear and pull-off force required for effective engagement can vary
significantly. Generally, the closer the spacing and the greater amount of hook
elements employed will result in increased shear and pull-off forces upon engagement.
The first and second head elements
17 and
21 of hook elements
18
and
22 preferably have a similar shape configured to become engaged with
one another upon the pressing contact of the first portion
12 with the second
portion
14. The first and second head elements
17 and
21 of
hook elements
18 and
22 can have an inverted J-shaped orientation,
an L-shape, a knob shape, a multi-tined anchor, a T-shape, a key shape, or any
other form of a hook-like element that can function in the present system. Such
elements are referred to herein as "hook-like", "hook-type", or "hook" elements
whether or not they are in the shape of a hook. In an exemplary fastener, the "engaged"
mode, the first head elements
17 are substantially perpendicular to the
second head elements
21 (FIG. 5). In the "disengaged" mode the first head
elements
17 are substantially parallel to the second head elements
21
(FIG. 6).
The first and second head elements have a length and a width, wherein the length
is preferably longer than the width. A ratio of length versus width of the head
elements is preferably in the range from about 2 to 1 to about 10 to 1.
In a preferred embodiment, the second head elements comprise a housing that surrounds
the material adapted to change the directional orientation of the second head elements.
In a non-limiting example, FIG. 7 is a view of a second hook element
22,
and an interior view of the second head element
21. The material
34
adapted to change the directional orientation of the second head element is encased
in housing
32. Suitable materials for fabricating the housing include plastics,
metals, and the like. For example, suitable plastics include polytetrafluoroethylene
and thermoplastics such as for example polypropylene, polyethylene, polyamide,
polyester, polystyrene, polyvinyl chloride, acetal, acrylic, polycarbonate, polyphenylene
oxide, polyurethane, polysulfone, and other like thermoplastic polymers.
Suitable materials for providing the directional orientation changing capability
of the second head elements of the second hook elements include, but are not limited
to, magnetic materials, magnetorheological fluids, magnetorheological elastomers,
and the like.
Suitable magnetic materials include, but are not intended to be limited
to, soft or hard magnets; hematite; magnetite; magnetic material based on iron,
nickel, and cobalt, alloys of the foregoing, or combinations comprising at least
one of the foregoing, and the like. Alloys of iron, nickel and/or cobalt, can comprise
aluminum, silicon, cobalt, nickel, vanadium, molybdenum, chromium, tungsten, manganese
and/or copper.
Suitable MR fluid materials include, but are not intended to be limited
to, ferromagnetic or paramagnetic particles dispersed in a carrier fluid. Suitable
particles include iron; iron alloys, such as those including aluminum, silicon,
cobalt, nickel, vanadium, molybdenum, chromium, tungsten, manganese and/or copper;
iron oxides, including Fe
2O
3 and Fe
3O
4;
iron nitride; iron carbide; carbonyl iron; nickel and alloys of nickel; cobalt
and alloys of cobalt; chromium dioxide; stainless steel; silicon steel; and the
like. Examples of suitable particles include straight iron powders, reduced iron
powders, iron oxide powder/straight iron powder mixtures and iron oxide powder/reduced
iron powder mixtures. A preferred magnetic-responsive particulate is carbonyl iron,
preferably, reduced carbonyl iron.
The particle size should be selected so that the particles exhibit multi-domain
characteristics when subjected to a magnetic field. Diameter sizes for the particles
can be less than or equal to about 1000 micrometers, with less than or equal to
about 500 micrometers preferred, and less than or equal to about 100 micrometers
more preferred. Also preferred is a particle diameter of greater than or equal
to about 0.1 micrometer, with greater than or equal to about 0.5 more preferred,
and greater than or equal to about 10 micrometers especially preferred. The particles
are preferably present in an amount between about 5.0 to about 50 percent by volume
of the total MR fluid composition.
Suitable carrier fluids include organic liquids, especially non-polar organic
liquids. Examples include, but are not limited to, silicone oils; mineral oils;
paraffin oils; silicone copolymers; white oils; hydraulic oils; transformer oils;
halogenated organic liquids, such as chlorinated hydrocarbons, halogenated paraffins,
perfluorinated polyethers and fluorinated hydrocarbons; diesters; polyoxyalkylenes;
fluorinated silicones; cyanoalkyl siloxanes; glycols; synthetic hydrocarbon oils,
including both unsaturated and saturated; and combinations comprising at least
one of the foregoing fluids.
The viscosity of the carrier component can be less than or equal to about 100,000
centipoise, with less than or equal to about 10,000 centipoise preferred, and less
than or equal to about 1,000 centipoise more preferred. Also preferred is a viscosity
of greater than or equal to about 1 centipoise, with greater than or equal to about
250 centipoise preferred, and greater than or equal to about 500 centipoise especially preferred.
Aqueous carrier fluids may also be used, especially those comprising hydrophilic
mineral clays such as bentonite or hectorite. The aqueous carrier fluid may comprise
water or water comprising a small amount of polar, water-miscible organic solvents
such as methanol, ethanol, propanol, dimethyl sulfoxide, dimethyl formamide, ethylene
carbonate, propylene carbonate, acetone, tetrahydrofuran, diethyl ether, ethylene
glycol, propylene glycol, and the like. The amount of polar organic solvents is
less than or equal to about 5.0% by volume of the total MR fluid, and preferably
less than or equal to about 3.0%. Also, the amount of polar organic solvents is
preferably greater than or equal to about 0.1%, and more preferably greater than
or equal to about 1.0% by volume of the total MR fluid. The pH of the aqueous carrier
fluid is preferably less than or equal to about 13, and preferably less than or
equal to about 9.0. Also, the pH of the aqueous carrier fluid is greater than or
equal to about 5.0, and preferably greater than or equal to about 8.0.
Natural or synthetic bentonite or hectorite may be used. The amount of bentonite
or hectorite in the MR fluid is less than or equal to about 10 percent by weight
of the total MR fluid, preferably less than or equal to about 8.0 percent by weight,
and more preferably less than or equal to about 6.0 percent by weight. Preferably,
the bentonite or hectorite is present in greater than or equal to about 0.1 percent
by weight, more preferably greater than or equal to about 1.0 percent by weight,
and especially preferred greater than or equal to about 2.0 percent by weight of
the total MR fluid.
Optional components in the MR fluid include clays, organoclays, carboxylate
soaps, dispersants, corrosion inhibitors, lubricants, extreme pressure antiwear
additives, antioxidants, thixotropic agents and conventional suspension agents.
Carboxylate soaps include ferrous oleate, ferrous naphthenate, ferrous stearate,
aluminum di- and tri-stearate, lithium stearate, calcium stearate, zinc stearate
and sodium stearate, and surfactants such as sulfonates, phosphate esters, stearic
acid, glycerol monooleate, sorbitan sesquioleate, laurates, fatty acids, fatty
alcohols, fluoroaliphatic polymeric esters, and titanate, aluminate and zirconate
coupling agents and t
