Folding kayak

Information

  • Patent Grant
  • 6371042
  • Patent Number
    6,371,042
  • Date Filed
    Wednesday, April 26, 2000
    24 years ago
  • Date Issued
    Tuesday, April 16, 2002
    22 years ago
Abstract
A collapsible boat comprising forward and aft hull sections, each of which comprising a plurality of longitudinal frame members and transverse cross members. The frame members are joined into longitudinal alignment by sliding a male end of a frame member into a complimentary female end of an adjacent frame member. The frame members are also interconnected to the cross members at a plurality of connector portions to create the forward and aft hull sections. Interlocking mechanisms are used to join together the forward and aft hull sections to define a hull framework having elongate frame members that extend longitudinally between a bow and stern and that are spaced and braced by transversely extending cross members. A variable tensioning mechanism permits variation of the elevation of the bow and stem of the framework by adjusting the overall length of the elongate frame members. The framework is insertable into a flexible water impermeable skin to create a boat with adjustable handling characteristics suitable for use in a wide variety of water conditions and environments. The water impermeable skin is provided with one or more water resistant hatch for loading and unloading of the collapsible boat, and a central cockpit opening having a removable coaming and a resealable deck slit to provide for an enlarged opening through which the forward and aft hull sections may be inserted in assembling the framework.
Description




FIELD OF THE INVENTION




This invention relates to a collapsible boat in which a skin or shell of waterproof material covers a collapsible internal framework of rigid members.




BACKGROUND OF THE INVENTION




Collapsing or foldable boats such as kayaks or canoes are well known and have been commercially available for many years. The following patents, for example, disclose water craft that are designed to be collapsed from a watergoing form into a relatively compact form for storage and/or transportation: U.S. Pat. No. 389,817 to King; U.S. Pat. No. 1,649,311 to Kaechele; U.S. Pat. No. 2,415,495 to Humphreys; U.S. Pat. No. 3,123,841 to Bronner; U.S. Pat. No 3,869,743 to Brown; U.S. Pat. No, 4,004,307 to Hermann; U.S. Pat. No. 4,057,865 to Trautwein; U.S. Pat. No. 4,274,170 to Simpson; U.S. Pat. No. 4,407,216 to Masters; U.S. Pat. No. 4,480,579 to Masters; U.S. Pat. No. 4,841,899 to Fleckles; and U.S. Pat. No. 5,875,731 to Abernethy et al.




SUMMARY OF THE INVENTION




In one aspect, the invention provides a collapsible boat comprising forward and aft hull sections, each of which comprising a plurality of longitudinal frame members and transverse cross members. The frame members are joined into longitudinal alignment by sliding a male end of a frame member into a complimentary female end of an adjacent frame member. The frame members are also interconnected to the cross members at a plurality of connector portions to create the forward and aft hull sections. Interlocking mechanisms are used to join together the forward and aft hull sections to define a hull framework having elongate frame members that extend longitudinally between a bow and stern and that are spaced and braced by transversely extending cross members. A variable tensioning mechanism permits variation of the elevation of the bow and stern of the framework by adjusting the overall length of the elongate frame members. In some embodiments, the present invention accordingly provides a vessel that may be adapted to handle different water conditions by allowing the user to vary the rocker while in the boat, without having to paddle to shore to make the adjustments. The framework is insertable into a flexible water impermeable skin to create a boat with adjustable handling characteristics suitable for use in a wide variety of water conditions and environments. The water impermeable skin is provided with one or more water resistant hatches for loading and unloading of the collapsible boat, and a central cockpit opening having a removable coaming and a resealable deck slit to provide for an enlarged opening through which the forward and aft hull sections may be inserted in assembling the framework.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a top plan view of a folding kayak in accordance with one embodiment of the invention.





FIG. 2

is side elevational view of a folding kayak of the invention, showing the internal framework.





FIG. 3

is a cross-sectional view along the section indicated by arrows in FIG.


2


.





FIG. 4

is a partially broken away cross-sectional side view of a connection between frame members, showing the members fully engaged.





FIG. 5

is a partially broken away cross-sectional top view of a connection between frame members, showing the members partially engaged.





FIG. 6

is a partially broken away cross-sectional front view of a connection between frame members, showing the members partially engaged.





FIG. 7

is a top plan view of a tension mechanism of the invention.





FIG. 8

is a cross-sectional view of a tension mechanism along the line shown by arrows in FIG.


7


.





FIG. 9

is a partially broken away top plan view of a cockpit opening, showing a slit in the skin of the kayak in a closed configuration.





FIG. 10

is a partially broken away top plan view of a cockpit opening, showing a slit in the skin of the kayak in a partially open configuration.





FIG. 11

is a partially broken away top plan view of a cockpit opening, showing a slit in the skin of the kayak in an open configuration.





FIG. 12

is a partially broken away cross-sectional view of the sealing mechanism for sealing a slit in the skin of the kayak, along the line shown by an arrow in FIG.


9


.





FIG. 13

is a partially broken away cross-sectional view of a coaming member and associated apparatus used to form a cockpit opening, along the line shown by an arrow in FIG.


9


.





FIG. 14

is a side elevational view of a kayak, showing no rocker or keel curvature.





FIG. 15

is a side elevational view of a kayak, showing rocker and keel curvature.





FIG. 16

is a side elevational view of a kayak, showing rocker and keel curvature.





FIG. 17

is a top plan view of a lid for a hatch.





FIG. 18

is a cross-sectional view showing a lid for a hatch, along the section line shown by an arrow in FIG.


17


.





FIG. 19

is a top plan view of a hatch opening, showing top and bottom hatch portions defining the hatch opening.





FIG. 20

is a cross-sectional view showing the top and bottom hatch portions defining the hatch opening, along the section line shown by an arrow in FIG.


19


.





FIG. 21

is a cross-sectional side view showing the hatch lid and hatch portions assembled on the hatch opening, showing the hatch lid in phantom lines in an open configuration.











DETAILED DESCRIPTION OF THE INVENTION




Referring to

FIGS. 1 and 2

, there is shown a kayak


2


and a kayak internal framework


4


constructed according to a preferred embodiment of the present invention. In

FIG. 1

, the framework


4


is covered by a flexible water impermeable layer or skin


6


that conforms closely to the shape of the framework. The kayak


2


has a bow


10


and a stem


12


and a central cockpit


14


.




Internal framework


4


comprises a forward hull section


16


and an aft hull section


18


, each hull section has elongate longitudinal members including forward and aft keel members


22


and


24


, port and starboard forward gunwale members


26


and


28


and port and starboard forward stringer members


30


and


32


. As best shown in the hull cross-section of

FIG. 3

, the framework also includes port and starboard aft gunwale member portions


34


and


36


and port and starboard aft stringer members


38


and


40


.




The longitudinal keel, gunwale and stringer members are formed from a plurality of longitudinal frame members


42


that are connected end to end at connection


44


to form the elongate longitudinal members that define forward and aft hull sections


16


and


18


, respectively, Cross members


50


extend transversely between the elongate longitudinal members at connections


44


to brace and space the longitudinal members. In the kayak configuration illustrated, forward and aft elongate deck members


52


and


54


, respectively, are also provided between forward and aft port and starboard gunwale member portions


26


,


28


and


34


,


36


to support skin


6


over the top of the framework. It will be readily apparent to those skilled in the art that the framework structure of the present invention is not limited to use in a kayak. The internal framework of the present invention can be readily designed to define the hull of other small water vessels such as a canoe. However, for the purposes of illustration only, the embodiment described is a kayak.




Forward and aft hull sections


16


and


18


include a bow or stem plate


56


and


58


, respectively, to which the gunwale, stringer and deck members are releasably fastened. Plates


56


and


58


are preferably rigidly attached by welding to the ends of the outermost keel member portions


22


and


24


respectively. The plates are suitably shaped to define a smoothly rounded bow and stem to the kayak beneath skin


6


. Adjacent keel, gunwale, deck and stringer member portions for connection end-to-end are preferably joined by elastic cords (not shown) so that the various member portions can remain connected by the cords when the framework is collapsed into component parts to prevent losing parts. All the longitudinal members and cross-rib members are preferably aluminum alloy tubes selected for their lightweight, strength and corrosion resistance.




The forward and aft hull sections


16


and


18


are joined in the cockpit region of the kayak by an interlocking mechanism


62


, or by a variable tension mechanism


64


, that joins together corresponding keel, gunwale and stringer members from the forward and aft hull sections. A variable tension mechanism


64


may be provided for all elongate frame members but it will be readily apparent to those skilled in the art that the necessary adjustments may be accomplished by three tensioning mechanisms: one between forward and aft keel members


22


and


24


, one between forward and aft starboard gunwale members


28


and


36


, and one between forward and aft starboard gunwale members


28


and


36


, and one between forward and aft port gunwale members


26


and


34


. The variable tension mechanism


64


permits variation of the elevation of the bow and stem of the framework by adjusting the overall length of the gunwale and/or the keel members as will be described. Port and starboard forward and aft stringer members


30


,


32


and


40


may be respectively joined together by interlocking mechanism


62


. The result is an assembled framework as illustrated in

FIG. 2

that defines a hull having elongate keel, gunwale and stringer members that extend longitudinally between bow


10


and stem


12


and that are spaced and braced by the transverse cross members


50


.




Referring to

FIG. 4

,


5


and


6


, there is shown a detail view of a typical connection


44


for joining various longitudinal frame members end to end and to transverse cross members


50


. Each connection


44


comprises an end of a first portion


70


of a frame member having a male end


72


and an adjacent end of a second portion


74


of an adjacent frame member having a complementary opening or female end


76


to receive the male end therein. The cross members


50


have a plurality of connector portions


80


spaced around the periphery of the cross member's peripheral edge


82


. The connector portions


80


of the cross member


50


comprises a projection


84


having a shaft


86


and an enlarged end


88


which may be inserted into a first opening


90


in the second portion


74


of frame members


42


. Cross member


50


is secured to frame member


42


by inserting the projection


84


into a first opening


90


and then inserting male end


72


of an adjacent frame member Into the female end


76


in direction


77


so that the male end of the adjacent frame member engages the enlarged end


88


of projection


84


. The male end


72


may be provided with a longitudinal slot dimension to fit around shaft


86


so as to engage enlarged end


88


more fully. In the preferred embodiment, it is necessary to lock together the male and female portions of each connection


44


to reduce the possibility of the frame members becoming unintentionally separated from each other. In

FIGS. 4 and 5

, a locking mechanism is illustrated comprising a second opening


92


in female end and a depressible protrusion or button


94


on the male end that is spring biased


96


to protrude outwardly from the male end. When male end


72


is inserted into female end


76


, button


94


extends into second opening


92


to lock the male and female ends together on alignment of second opening


92


and button


94


.




Referring to

FIGS. 7 and 8

, there is shown the variable tension mechanism


64


of the present invention. Tension mechanism


64


is telescoping so that it is insertable between and connectable to forward and aft longitudinal members. Tension mechanism


64


includes a telescoping member


100


comprising an outer tube


102


with a first end


104


and a second end


106


that is insertable into the female end of a frame member from the forward or aft hull sections that extends into the central cockpit region


60


of the framework. Telescoping member


100


also includes an inner tube


108


slideable within the outer tube and extending from the first end


104


of the outer tube


102


, and having an end


110


being insertable into the female end of an adjacent frame member from the forward or aft hull sections that extends into the central cockpit region


60


of the framework. Such female end of frame members from forward or aft frame sections is provided with a stop, the structure of which would be apparent to a person skilled in the art, to limit the distance that ends


104


and


110


may be inserted into the female end. A rod


112


, preferably formed with a ratcheted surface


114


, is movably disposed within the outer tube of the telescoping member and having one end


116


connected to the inner tube


108


. An actuator in the form of a guide


120


is provided about rod


112


and connected to the outer tube


102


by an arm


122


. A lever


124


is connected to the arm


122


by pivot


126


. Lever


124


includes a pin


128


and a dog


130


that is engageable with the ratcheted surface


114


of the rod


112


to move the rod and inner tube in the direction


132


to extend the telescopic member


100


. As lever


124


is raised in direction


134


about the pivot


126


, the pin


128


pushes the top portion of dog


130


in direction


132


which engages the ratcheted surface of the rod forcing the rod in direction


132


. Rod


112


is free to move in direction


132


through opening


144


in locking member


140


. When lever


124


is lowered in a direction opposite to direction


134


, spring


142


acts on the locking member


140


causing it to pivot such that opening


144


is misaligned with rod


112


and the opening engages the ratcheted surface


114


thereby acting as a lock on the rod preventing the rod from moving counter to direction


132


. As the lever


124


is lowered, spring


146


acts on dog


130


which slips back on the rod to its starting position. To disengage locking member


140


to allow the telescoping member


100


to shorten, locking member


140


has a handle


148


by which the locking member is pivoted to align hole


144


with rod


112


such that member


140


is disengaged from the ratcheted surface. When the handle


148


is moved in direction


149


, rod


112


is thereby allowed to move in a direction opposite of direction


132


.




When assembling the collapsible kayak of the present invention, the forward and aft hull sections


16


and


18


are constructed initially and inserted into the ends of skin


6


as illustrated in FIG.


1


. Referring to

FIG. 9 through 13

, skin


6


has a central cockpit opening


200


and a deck slit


202


extending from the cockpit opening


200


to allow for enlargement of the cockpit opening to permit the hull sections to be inserted into the skin. The skin


204


adjacent the cockpit opening


200


has a collar


206


attached thereto with an enlarged edge


208


. The comers


210


and


212


located where the deck slit


202


converges with the cockpit opening have fasteners


214


and


216


that are connectable with one another. As well, the skin


218


adjacent the deck slit has sealing portions


220


and


222


with enlarged edges. Once the forward and aft hull sections are inserted into skin


6


, the corresponding forward and aft keel members, gunwale members and stringer members of each hull section are connected by interlocking mechanism


62


or variable tension mechanism


64


, as the case may be. The variable tension mechanism


64


is maintained in place by the inwardly acting longitudinal forces resulting from the tension of the skin


6


acting on the framework


4


. A rigid annular coaming member


224


is then inserted into the cockpit opening


200


. The coaming member


224


has a central body


226


dimensioned for a close fit within the cockpit opening, and top and bottom portions


228


and


230


radiating outwardly from the central body such that a cross section of the coaming member generally defines a “U”-shape and forms a channel


232


around the periphery of the coaming member. The collar


206


is drawn around the channel


232


of the coaming member


224


and fasteners


214


and


216


are drawn towards each other and connected. The sealing portions


220


and


222


are drawn together and a sealing mechanism, in the preferred embodiment, an elongated member


234


having a longitudinal channel


236


and inwardly extending flange portions


238


and


240


along the length of the channel, is slid over the sealing portions to engage the enlarged edges and maintain them in contact with each other to form a waterproof seal.




The variable tension mechanisms operate to change the length of the keel, gunwale or stringer members. As the gunwale length shortens, the bow


10


and stern


12


of the boat rise thus increasing the rocker or curvature of the keel. The shorter the gunwale length, the higher the bow


10


and stern


12


and the greater the rocker.

FIG. 14

shows a kayak with no rocker or keel curvature which is appropriate for flat water conditions to assist in keeping the kayak travelling in a straight line.

FIGS. 15 and 16

show different rocker positions with an increasingly curved keel. In general, the greater the curvature or rocker of the keel, the greater the turning ability of the kayak hull. Furthermore, by lengthening or shortening one gunwale member in relation to the other gunwale member the lateral curvature of the kayak may be adjusted to give the kayak a tendency to yaw to one side. The ability to adjust the yaw of a kayak is advantageous in compensating for the tendency of the kayak to drift laterally in a cross-wind or cross-current.




Also provided in the present invention is one or more hatches


250


in the skin to allow for more convenient loading of gear into the hull of the kayak. Referring to

FIGS. 17 through 21

, the deck portion of the skin


6


has a hatch opening


252


. Around the hatch opening


252


is an annular top hatch portion


254


having a material contact surface


256


dimensioned for conformable contact with the outer surface


258


of the skin adjacent the hatch opening. On the inner surface


260


of the skin


6


is an annular bottom hatch portion


262


dimensioned for a conformable fit with the contact surface


256


of the top hatch portion


254


and the inner surface


260


of the skin adjacent to the hatch opening


252


. The top and bottom hatch portions


254


and


262


with the skin


6


sandwiched therebetween are connected to one another by a plurality of connectors


264


extending between the top hatch portion and the bottom hatch portion. The top batch portion


254


also has a lid end


266


opposite the contact surface


256


that has a flange


268


extending radially therefrom such that a cross section of the top hatch portion tends to resemble an inverted “L”. The hatch


250


also includes a lid


270


dimensioned for a conformable and generally waterproof fit over the top hatch portion


254


and having an engaging end


272


with a flange


274


extending downwardly and inwardly which engages the flange


268


on the top hatch portion


254


. The lid


270


also has a locking end


276


opposite the engaging end and having a locking mechanism comprising an actuator such as a dial


280


seated in a depression


282


in the lid and a portion


284


of the dial


280


extending through a hole


286


in the lid to engage a latch portion


290


that is movably mounted on the inner surface of the lid. The actuator engages the latch causing it to move between a first position in which the latch portion does not impede the removal of the lid from the hatch, and a second position in which the latch portion engages the hatch so as to impede the removal of the lid from the hatch. Also, in the preferred embodiment, the latch portion


290


has a leading edge that tapers to a thicker trailing edge so that the leading edge engages the hatch prior to the trailing edge as the latch portion is moved from first position to second position thereby gradually increasing the locking tension on the lid.




Although the present invention has been described in some detail by way of example for purposes of clarity and understanding, it will be apparent that certain changes and modifications may be practiced within the scope of the appended claims. Many adaptations and modifications may be made within the scope of the invention in accordance with the common general knowledge of those skilled in this art. Such modifications include the substitution of known equivalents for any aspect of the invention in order to achieve the same result in substantially the same way. Numeric ranges are inclusive of the numbers defining the range. In the claims, the word “comprising” is used as an open-ended term, substantially equivalent to the phrase “including, but not limited to”.



Claims
  • 1. A collapsible boat comprising:forward and aft hull sections, each hull section comprising: a plurality of longitudinal frame members, each frame member having a male end and a female end adapted to receive the male end of an adjacent frame member for releasably connecting therewith, the female end further having a connector portion, and a plurality of generally planar rigid transverse cross members having a peripheral edge with a plurality of connector portions thereon for cooperatively interconnecting with the connector portion of the female end of the frame member thereby when the frame members are connected to the connector portions on the cross members they define a rigid hull section of a framework, a flexible water impermeable skin for covering the framework, the skin having a central cockpit opening and a shape to receive forward and aft frame sections of the framework through the cockpit opening for subsequently joining and locking of the frame sections, and interlocking mechanisms having end portions which are releasably connectable to the forward and aft frame sections thereby permitting the forward and aft frame sections to be joined in longitudinal alignment to form the framework.
  • 2. The collapsible boat as claimed in claim 1 in which:the connector portion on the cross members comprises a projection from the peripheral edge of the cross member having a shaft and an enlarged end, and the connector portion on the female end of the frame members has a shape to cooperatively receive the enlarged end for releasable interlocking engagement with the enlarged end thereby releasably interconnecting the frame member to the cross member.
  • 3. The collapsible boat as claimed in claim 2 in which:the connector portion on the female end of the frame members comprises a first opening in the female end to receive the enlarged end of the projections and the male end of an adjacent frame member engages the enlarged end of the connector portion of the cross member when the enlarged end is inserted into the first opening and the male end is inserted into the female end.
  • 4. The collapsible boat as claimed in claim 3 further comprising a locking mechanism on the frame members to lock adjacent frame members together once the male end of one frame member is inserted into the female end of an adjacent frame member thereby reducing the possibility of the frame members becoming unintentionally separated.
  • 5. The collapsible boat as claimed in claim 4 in which the locking mechanism comprises:an opening in the male end, a second opening in the female end of an adjacent frame member that aligns with the opening in the male end when the male end is inserted into the female end, and a releasable projection protruding through the opening in the male end and the second opening in the female end thereby interlocking the frame members to reduce the possibility of them becoming unintentionally separated.
  • 6. The collapsible boat as claimed in claim 5 in which the projection is a depressible protrusion on the male end biased to protrude outwardly from the male end such that the protrusion extends into the second opening to lock the male and female ends together on alignment of the second opening and the protrusion.
  • 7. The collapsible boat as claimed in claim 4 in which at least one of the interlocking mechanisms comprises a variable tension mechanism to permit variable and incremental adjustment of the length of the framework.
  • 8. The collapsible boat as claim 7 in which the variable tension mechanism comprises:a telescoping member comprising an outer frame having a first end and a second end adapted to engage an exposed end of an adjacent frame member for releasably connecting therewith, and further having a longitudinal opening along a section of the outer frame, a rod movably mounted within the outer frame and having an end protruding from the open end of the outer frame which is adapted to engage an exposed end of an adjacent frame member for releasably connecting therewith, an actuator in connection with the outer frame and being engageable with the rod through the longitudinal opening in the outer frame so that when the user exerts a force upon the actuator, the actuator acts on the rod causing it to move longitudinally thereby resulting in the telescoping member becoming elongated, the actuator further being releasable from engagement with the rod when the user releases the force so that the actuator may be returned to its original position, and a locking member in connection with the outer frame and having an engaging portion being in releasable engagement with the rod through the longitudinal opening in the outer frame, the engaging portion permitting movement of the rod in the direction of travel in which the actuator acts upon the rod, but restricting travel in the opposite directions.
  • 9. The collapsible boat as claimed in claim 8 in which the water impermeable skin further includes:an inner surface and an outer surface, a hatch opening, and a hatch comprising, an annular top hatch portion having a skin contact surface dimensioned for conformable contact with the outer surface of the skin adjacent the hatch opening, an annular bottom hatch portion dimensioned for a conformable fit with the contact surface of the top hatch portion and the inner surface of the skin adjacent to the hatch opening, a plurality of connectors extending between the top hatch portion and the bottom hatch portion to connect the top hatch portion to the bottom hatch portion thereby sandwiching the skin adjacent the hatch opening therebetween, a lid dimensioned for a conformable and generally waterproof fit over the top hatch portion a securing mechanism to engage the lid upon the top hatch portion.
  • 10. The collapsible boat as claimed in claim 9 in whichthe annular top hatch portion has a lid end opposite the contact surface and has a flange extending radially from the lid end, the lid has an engaging end with a flange extending downwardly and inwardly for engaging the flange of the lid end of the top hatch portion, and a locking end opposite the engaging end and having a locking mechanism for engaging the hatch.
  • 11. The collapsible boat as claimed in claimed in claim 10 wherein the lid defines an inner surface and an outer surface, and the locking mechanism of the lid further comprises:an opening in the lid near the locking end of the lid, a latch portion movably mounted on the inner surface of the lid, the latch portion being movable between a first position in which the latch portion does not impede the removal of the lid from the hatch, and a second position in which the latch portion engages the hatch so as to impede the removal of the lid from the hatch, and an actuator movably mounted on the outer surface of the lid and extending through the opening in the lid for engaging the latch portion and causing the latch portion to move between the first and the second position.
  • 12. The collapsible boat as claimed in claim 11 in which:the actuator on the locking portion of the hatch comprises a dial, and the lid has a depression adjacent to the opening to accommodate the dial so that the dial is generally flush with the outer surface of the lid.
  • 13. The collapsible boat as claimed in claim 12 in which the flexible water impermeable skin further includes:a deck slit extending from the cockpit opening, sealing portions on the edges of both sides of the skin adjacent the deck slit, a sealing mechanism for engaging the sealing portions to join the edges of the skin to one another thereby closing the deck slit, a generally rigid annular coaming member having a central body dimensioned for a close fit within the cockpit opening, and top and bottom portions radiating outwardly from the central body such that a cross section of the annular member tends to generally define a general “U”-shape forming a channel around the periphery of the central body, and skin adjacent the cockpit opening having a collar with an enlarged edge for conformable fit within the channel when the collar is drawn around the central body of the coaming member by closing the deck slit as described above, thereby providing a generally waterproof seal between the collar and the coaming member.
  • 14. The collapsible boat as claimed in claim 13 in which:the sealing portions comprise an enlarged edge of the skin adjacent the deck slit, and the sealing mechanism comprises an elongated member having a longitudinal channel, to accommodate the sliding of the elongated member over the enlarged edges when the edges are brought into proximity with each other, and further having flange portions extending inwardly along the length of the channel to engage the enlarged edges thereby limiting the removal of the elongated member to slideable movement in the direction of the deck slit.
US Referenced Citations (13)
Number Name Date Kind
389817 King Sep 1888 A
1649311 Kaechele et al. Nov 1927 A
2415495 Humphreys Feb 1947 A
3123841 Bronner Mar 1964 A
3869743 Brown et al. Mar 1975 A
4004307 Hermann Jan 1977 A
4057865 Trautwein Nov 1977 A
4274170 Simpson Jun 1981 A
4290157 Jensen, Jr. Sep 1981 A
4407216 Masters Oct 1983 A
4480579 Masters Nov 1984 A
4841899 Fleckles et al. Jun 1989 A
5875731 Abernethy et al. Mar 1999 A
Foreign Referenced Citations (1)
Number Date Country
2 539 097 Jul 1984 FR