Patent Grant
6851239
1. Field of the Invention
This invention relates to an improved reinforcement structure for cavity walls, and, more particularly, to combined wall anchors and reinforcement trusses or ladders that utilize true-joints to fuse together the components under high heat and high pressure. The resultant anchoring systems meet high flatness requirements facilitating the formation of uniform mortar bed joints. This avoids stackup tolerances and reduces the cutting of blocks to fit within the height requirements. The flatness of the combined wall reinforcement and wall anchor enables the mason to more easily maintain the verticality of the wall.
2. Description of the Prior Art
Recently, special attention has been drawn to products that not only improve a mason's productivity, but also aid in straighter joint lines and ultimately better looking buildings. Among these products are cavity wall anchoring systems that tie together backup walls and facing veneers. While the backup walls or inner wythes may be masonry blocks, dry wall construction or poured concrete, this invention provides several examples of true jointed wall reinforcements and wall anchors for use with masonry black backup walls.
To date, numerous anchoring devices for insertion in bed joints of the backup walls have been marketed. In the main, each of these devices have a portion thereof or a separate interengaging component that is inserted in a corresponding bed joint of the facing veneer. Backup walls of masonry blocks also have a requirement that joint reinforcement be used. Standards in the construction industry have evolved to include a masonry joint reinforcement standard, namely, ASTM Standard Specification A951-00 which describes joint reinforcement fabricated from cold drawn steel wire. As the production of better looking buildings requires uniformity in laying up the inner and the outer wythe, the competition for bed joint space between reinforcement materials and anchoring devices needs to be resolved in a manner satisfactory to the mason.
Over the past forty years there has been growing acceptance of wire formatives not only for wall reinforcements, but also for wall anchors and veneer anchors. It has become increasingly common to look toward a 0.375-inch high bed joint in both the inner wythe and the outer wythe. To maintain uniform joints, masons look toward mortar coverage above the reinforcement and wall anchor combination so that successive blocks are supported by the mortar layer and not by the wire formative. This enables the mason to adjust the placement of the block to maintain uniformity.
In the past, the use of wire formatives have been limited by the mortar layer thicknesses which, in turn are dictated either by the new building specifications or by pre-existing conditions, e.g. matching during renovations or additions the existing mortar layer thickness. While arguments have been made for increasing the number of the fine-wire anchors per unit area of the facing layer, architects and architectural engineers have favored wire formative anchors of sturdier wire. On the other hand, contractors find that heavy wire anchors, with diameters approaching the mortar layer height specification, frequently result in misalignment. Thus, these contractors look towards substituting thinner gage wire formatives which result in easier alignment of courses of block.
In the past, there have been investigations relating to the effects of various forces, particularly lateral forces, upon brick veneer construction having wire formative anchors embedded in the mortar joint of anchored veneer walls. The seismic aspect of these investigations were referenced in the first-named inventor's prior patents, namely, U.S. Pat. Nos. 4,875,319 and 5,408,798. Besides earthquake protection, the failure of several high-rise buildings to withstand wind and other lateral forces has resulted in the incorporation of a requirement for continuous wire reinforcement in the Uniform Building Code provisions. The first-named inventor's related SeismiclipR and DW-10-XR products (manufactured by Hohmann & Barnard, Inc., Hauppauge, N.Y. 11788) have become widely accepted in the industry. The use of a wire formative anchors in masonry veneer walls has also demonstrated protectiveness against problems arising from thermal expansion and contraction and has improved the uniformity of the distribution of lateral forces in a structure. However, these investigations do not address the mortar layer thickness vs. the wire diameter of the wire formative or technical problems arising therefrom.
In the course of preparing this disclosure several patents became known to the inventors hereof. The following patents are believed to be relevant and are discussed further as to the significance thereof:
It is noted that with some exceptions these devices are generally descriptive of wire-to-wire anchors and wall ties and have various cooperative functional relationships with straight wire runs embedded in the interior and/or exterior wythe. Several of the prior art items are of the pintle and eyelet/loop variety.
U.S. Pat. No. 3,377,764—D. Storch—Issued Apr. 16, 1968
Discloses a bent wire, tie-type anchor for embedment in a facing exterior wythe engaging with a loop attached to a straight wire run in a backup interior wythe.
U.S. Pat. No. 4,021,990—B. J. Schwalberg—Issued May 10, 1977
Discloses a dry wall construction system for anchoring a facing veneer to wallboard/metal stud construction with a pronged sheet-metal anchor. Like Storch '764, the wall tie is embedded in the exterior wythe and is not attached to a straight wire run.
U.S. Pat. No. 4,373,314—J. A. Allan—Issued Feb. 15, 1983
Discloses a vertical angle iron with one leg adapted for attachment to a stud; and the other having elongated slots to accommodate wall ties. Insulation is applied between projecting vertical legs of adjacent angle irons with slots being spaced away from the stud to, avoid the insulation.
U.S. Pat. No. 4.473,984—Lopez—Issued Oct. 2, 1984
Discloses a curtain-wall masonry anchor system wherein a wall tie is attached to the inner wythe by a self-tapping screw to a metal stud and to the outer wythe by embedment in a corresponding bed joint. The stud is applied through a hole cut into the insulation.
U.S. Pat. No. 4,869,038—M. J. Catani—Issued 091/26/89
Discloses a veneer wall anchor system having in the interior wythe a truss-type anchor, similar to Hala et al. '226, supra, but with horizontal sheetmetal extensions. The extensions are interlocked with bent wire pintle-type wall ties that are embedded within the exterior wythe.
U.S. Pat. No. 4,879,319—R. Hohmann—Issued Oct. 24, 1989
Discloses a seismic construction system for anchoring a facing veneer to wallboard/metal stud construction with a pronged sheet-metal anchor. Wall tie is distinguished over that of Schwalberg '990 and is clipped onto a straight wire run.
U.S. Pat. No. 5,392,581—Hatzinikolas et al.—Issued Feb. 28, 1995
Discloses a cavity-wall anchor having a conventional tie wire for mounting in the brick veneer and an L-shaped sheetmetal bracket for mounting vertically between side-by-side blocks and horizontally on atop a course of blocks. The bracket has a slit which is vertically disposed and protrudes into the cavity. The slit provides for a vertically adjustable anchor.
U.S. Pat. No. 5,408,798—Hohmann—Issued Apr. 25, 1995 and U.S. Pat. No. 5,454,200—Issued Oct. 3, 1995
Discloses a seismic construction system for a cavity wall having a masonry anchor, a wall tie, and a facing anchor. Sealed eye wires extend into the cavity and wire wall ties are threaded therethrough with the open ends thereof embedded with a Hohmann '319 (see supra) clip in the mortar layer of the brick veneer. The Hohmann '200 patent is noted for the positive interengagement of the veneer anchor with the insertion end thereof sealed in the bed joint of the outer wythe.
U.S. Pat. No. 5,456,052—Anderson et al.—Issued Oct. 10, 1995
Discloses a two-part masonry brick tie, the first part being designed to be installed in the inner wythe and then, later when the brick veneer is erected to be interconnected by the second part. Both parts are constructed from sheetmetal and are arranged on substantially the same horizontal plane.
U.S. Pat. No. 5,816,008—Hohmann—Issued Oct. 15, 1998
Discloses a brick veneer anchor primarily for use with a cavity wall with a drywall inner wythe. The device combines an L-shaped plate for mounting on the metal stud of the drywall and extending into the cavity with a T-head bent stay. After interengagement with the L-shaped plate the free end of the bent stay is embedded in the corresponding bed joint of the veneer.
U.S. Pat. No. 6,209,281—Rice—Issued Apr. 3, 2001
Discloses a masonry anchor having a conventional tie wire for mounting in the brick veneer and sheetmetal bracket for mounting on the metal-stud-supported drywall. The bracket has a slit which is vertically disposed when the bracket is mounted on the metal stud and, in application, protrudes through the drywall into the cavity. The slit provides for a vertically adjustable anchor.
U.S. Pat. No. 6,279,283—Hohmann et al.—Issued Aug. 28, 2601
Discloses a low-profile wall tie primarily for use in renovation construction where in order to match existing mortar height in the facing wythe a compressed wall tie is embedded in the bed joint of the brick veneer.
None of the above provide the masonry cavity wall construction system for an inner masonry wythe and an outer facing wythe with high-span anchoring wire formatives as described hereinbelow.
In general terms, the invention disclosed hereby includes an anchoring system for a cavity wall. The embodiments described hereinbelow all utilize true-joint construction to reduce the height of wall reinforcement and wall anchor combinations, and thereby enable the erection of masonry block backup walls with highly uniform bed joint thicknesses and readily maintained verticality. Both the wall reinforcement and the wall anchor are wire formative elements and the elements, upon being joined, are fused together under heat and pressure. To accomplish this, the combined finished height of the assemblage of the wall reinforcement and wall anchor is limited to no greater than the diameter of wire used to form the wall anchor. By using the technique presented hereinbelow, ample mortar coverage is provided which, in turn, contributes to the accuracy of construction.
The embodiment of the invention disclosed hereby include a veneer anchoring system incorporating a swaged, double loop lock wall anchor in combination with a swaged, ladder-type wall reinforcement for use in the construction of a wall having an inner wythe with strips of insulation attached thereto. The seams between the strips of insulation are coplanar with the inner wythe bed joints. The compressively reduced in height wall anchors protrude into the cavity through the seams, which seams seal thereabout so as to maintain the integrity of the insulation and minimize air leakage along the wall anchors. In a second embodiment, wherein a truss-type wall reinforcement is used with a horizontal eye and pintle interengaging veneer anchor only the wall reinforcement is swaged. The invention contemplates that some components of the system are as described in U.S. Pat. Nos. 5,408,798; 5,454,200; and 6,279,283 and that the wire formatives hereof provide a positive interlocking connection therebetween specific for the requirements created by this true-joint application.
In the third embodiment of the invention, a box ladder-type wall reinforcement is used with a masonry block corner wythe. Here, the wall reinforcement has cross rods forming a T-head that extends into the cavity. The cross rods extend across the insulation into the cavity between the wythes. Each pair of cross rods is formed into a T-head to accommodate the threading thereinto of a wire formative veneer anchor of a bent box configuration inserted through the opening in the wall anchor. The veneer anchor is then positioned so that the insertion end is embedded in the facing wall. Wall anchors that are of limited height are described as being mounted in bed joints of the inner wythes. The close control of overall heights permits the mortar of the bed joints to flow over and about the wall reinforcement and wall anchor combination inserted in the inner wythe and insertion end of the veneer anchor in the outer wythe. The wire formatives hereof enable the anchoring system to meet the unusual requirements demanded.
It is an object of the present invention to provide in a wall structure having a cavity formed by an outer wythe and an inner wythe, an anchoring system which employs true-joint wire formatives in the mortar joint of the inner wythe and is positively interconnected with a veneer tie inserted into the outer wythe.
It is another object of the present invention to provide labor-saving devices combining wall reinforcements and wall anchors to aid in the installation of inner wythe structures and providing for the securement thereto of facing veneers.
It is yet another object of the present invention to provide through utilizing true-joint techniques an anchoring system of low height and high flatness for wall reinforcement of the inner wythe.
It is a further object of the present invention to provide an anchoring system comprising a limited number of component parts that are economical of manufacture resulting in a relatively low unit cost.
It is yet another object of the present invention to provide an anchoring system which is easy to install and which meets seismic and shear resistance requirements.
It is a feature of the present invention that the flatness of the combined wall reinforcements and wall anchors facilitates obtaining uniform mortar layer thicknesses throughout the structure and improves the overall quality and trueness thereof.
It is another feature of the present invention that the veneer anchor and the combined wall tie reinforcement and wall anchor are dimensioned with a sufficiently low height so that, when inserted into the respective mortar layers, the mortar thereof can flow around the insertions end thereof to form a stronger wall structure.
It is yet another feature of the present invention that a true-joint is employed to combine the wall reinforcement and the wall anchor.
Other objects and features of the invention will become apparent upon review of the drawing and the detailed description which follows.
In the following drawings, the same parts in the various views are afforded the same reference designators.
Before entering into the detailed Description of the Preferred Embodiments, several terms are while specifications may vary from one building to another, the bed joints are typically 0.375-inch (approx.) in height, defined, which terms will be revisited later, when some relevant analytical issues are discussed. For the purposes of this disclosure a true joint is defined as a juncture between two wire formatives wherein the elements are fusibly and interlockingly joined under heat and pressure. To improve the interlocking aspect of the joint one or both of the elements to be joined are cold-worked by swaging indentations therein which indentations receive a wire formative therewithin. The true joint of this invention also results in a juncture which is limited in height to be no greater than the diameter of the largest of the wire formatives.
Another term defined for purposes of this application is wall reinforcement. A wall reinforcement is a continuous length of Lox All® Truss Mesh or Lox All® Ladder Mesh manufactured by Hohmann & Barnard, Inc., Hauppauge, N.Y. 11788 or equivalent adapted for embedment into the horizontal mortar joints of masonry walls. The wall reinforcements are prefabricated from cold-drawn steel wire and have parallel side rods with butt welded cross rods or truss components. The wall reinforcements for true-joint anchoring systems are generally structured from 0.148- or 0.187-inch wire that complies with ASTM Specification A 951-00. The longitudinal wires of wall reinforcements are fabricated from steel, Type 304 SS, ASTM Specification A 580/A 580M, and are deformed to have a knurled surface therearound. When corrosion protection is specified, the wall reinforcement is provided with a mill or hot-dip galvanized finish, ASTM Specification A 641/A 641M or ASTM Specification A153/A 153M, respectively.
Referring now to
The cavity 22 is insulated with strips of insulation 23 attached to the exterior surface 24 of the inner wythe 14 and having seams 25 between adjacent strips 23 coplanar with adjacent bed joints 26 and 28. Successive bed joints 26 and 28 are formed between courses of blocks 16. The bed joints 26 and 28 are substantially planar and horizontally disposed and, while specifications may vary from one building to another, the bed joints are typically 0.375-inch (approx.) in height. Also, successive bed joints 30 and 32 are formed between courses of bricks 20 and the joints are substantially planar and horizontally disposed. Here again, while specifications may vary from one building to another, the bed joints are typically 0.375-inch (approx.) in height. Selected bed joint 26 and bed joint 30 are constructed to be interconnected utilizing the construct hereof.
For purposes of discussion, the cavity surface 24 of the inner wythe 14 contains a horizontal line or x-axis 34 and an intersecting vertical line or y-axis 36. A horizontal line or z-axis 38 also passes through the coordinate origin formed by the intersecting x- and y-axes. A wall anchor 40 is shown which has an insulation-spanning portion 42. Wall anchor 40 is a wire formative tie which is constructed for embedment in bed joint 26 and an interconnecting with veneer anchor 44.
The masonry or wall anchor 40 is adapted from one shown and described in Hohmann, U.S. Pat. No. 5,454,200, which patent is incorporated herein by reference. The wall anchor 40 is shown in
At intervals along the ladder-type reinforcement 46, spaced pairs of transverse wire members 54 are attached thereto and are attached to each other by a rear leg 56 therebetween. These pairs of wire members 54 extend into the cavity 22. The spacing therebetween limits the x-axis movement of the construct. Each transverse wire member 54 has at the end opposite the attachment end, an eye wire portion 58 formed continuous therewith. Upon installation, the eye 60 of eye wire portion 58 is constructed to be within a substantially vertical plane normal to exterior surface 24. The eye or veneer anchor receptor 60 is elongated vertically and accepts a veneer anchor threadedly therethrough. The anchor extends from eye 60, across the cavity 22, and into bed joint 30. The eye 60 is slightly wider than the wire diameter of the veneer anchor. This dimensional relationship minimizes the z-axis movement of the construct. For positive engagement, the eye 60 of eye wire portion 58 is sealed to form a closed loop.
The veneer anchor or box tie 44,
Referring now to
During assembly, the two components—the wall anchor 40 and the wall reinforcement 46—are fusibly joined at attachment sites 82, 84 and 88 under heat and pressure. Upon assembly, the true joints at the attachment sites 82, 84 and 88 have a height no greater than the diameter of the wire of wall anchor 40. Thus, for example, if the 0.187-inch diameter wire is employed for all components, upon insertion of the assemblage into bed joint 26 an equal height of mortar (as best seen in
During the cold working of system components in addition to the swaged indentations, the insertion end of anchor 44 and the insulation-spanning portion 42 of wall anchor 40 are compressively reduced in height. As described in a prior patent of the present inventors, namely, Hohmann et al., U.S. Pat. No. 6,279,283, the insertion ends of the veneer anchor is, upon cold-forming, optionally impressed with a pattern on the mortar-contacting surfaces. For this application, while several patterns—corrugated, diamond and cellular—are discussed in the patent, only the corrugated pattern is employed. The ridges and valleys of the corrugations are shown in
The cavity, as previously mentioned, has an insulation layer 23 which is shown in
The description which follows is of a second embodiment of the true-joint anchoring systems of this invention. For ease of comprehension, where similar parts are used reference designators “100” units higher are employed. Thus, the veneer anchor 144 of the second embodiment is analogous to the veneer anchor 44 of the first embodiment. Referring now to
For purposes of discussion, the exterior surface 124 of the interior wythe 114 contains a horizontal line or x-axis 134 and an intersecting vertical line or y-axis 136. A horizontal line or z-axis 138 normal to the xy-plane also passes through the coordinate origin formed by the intersecting x- and y-axes.
The wall anchor 140 is shown in
Referring now to
The veneer anchor 144 is, when viewed from a top or bottom elevation, generally U-shaped. The veneer anchor 144 is dimensioned to be accommodated by a pair of eye wire portions 158 described, supra. The veneer anchor 144 has two rear leg portions or pintles 162 and 164, two substantially parallel side leg portions 166 and 168, which are substantially at right angles and attached to the rear leg portions 162 and 164, respectively, and a front leg portion 170. An insertion portion 172 of veneer tie 144, which is considerably compressed upon installation extends beyond the cavity 122 into bed joint 130. Insertion portion 172 includes front leg portion 170 and part of side leg portions 166 and 168 upon compression, a pattern or corrugation 176 is impressed. The longitudinal axes of side leg portions 166 and 168 and the longitudinal axis of the front leg portion 170 are substantially coplanar.
The insertion portion 172 of veneer tie 144 is considerably compressed and, while maintaining the same mass of material per linear unit as the adjacent wire formative, the vertical height 174 is reduced. The vertical height 174 of insertion portion 172 is reduced so that, upon installation, mortar of bed joint 130 flows around the insertion portion 172. Upon compression, a pattern or corrugation 176 is impressed on either or both of the upper and lower surfaces of insertion portion 172. When the mortar of bed joint 130 flows around the insertion portion, the mortar flows into the valleys of the corrugations 176. The corrugations enhance the mounting strength of the veneer tie 144 and resist force vectors along the z-axis 138. With wall tie 144 compressed as described, the wall tie is characterized by maintaining substantially all the tensile strength as prior to compression.
In the second embodiment, and referring now to
During assembly, the two components—the wall anchor 140 and the wall reinforcement 146—are fusibly joined at attachment sites 182, 184 and 188 and 189 under heat and pressure. Upon assembly, the true joints at the attachment sites 182, 184,188 and 189 have a height no greater than the diameter of the wire of wall anchor 140. Thus, for example, if the 0.187-inch diameter wire is employed for all components, upon insertion of the assemblage into bed joint 126 an equal height of mortar would surround the wall reinforcement 146 and the insertion end of the wall anchor 140. As in the first embodiment, because of the flatness of the combined wall reinforcement and wall anchor assemblage, the ability to maintain verticality of the inner wythe is enhanced.
During the cold working of system components in addition to the swaged indentations, the insertion end of anchor 144 is compressively reduced in height. As described in a prior patent of the present inventors, namely, Hohmann et al., U.S. Pat. No. 6,279,283, the insertion ends of the veneer anchor is, upon cold-forming, optionally impressed with a pattern on the mortar-contacting surfaces. For this application, while several patterns—corrugated, diamond and cellular—are discussed in the patent, only the corrugated pattern is employed. The ridges and valleys of the corrugations are shown in
The description which follows is of a third embodiment of the high-span anchoring system of this invention. For ease of comprehension, where similar parts are used reference designators “200”units higher are employed. Thus, the wall anchor 240 of the third embodiment is analogous to the wall anchor 40 of the first embodiment. The veneer anchor of this embodiment is adapted from that shown in U.S. Pat. No. 5,454,200 to R. P. Hohmann; and the T-head, from that shown in U.S. Pat. No. 5,816,008 to R. P. Hohmann.
Referring now to
For purposes of discussion, the exterior surface 224 of the inner wythe 214 contains a horizontal line or x-axis 234 and an intersecting vertical line or y-axis 236. A horizontal line or z-axis 238 normal to the xy-plane also passes through the coordinate origin formed by the intersecting x- and y-axes. In the discussion which follows, it will be seen that the various anchor structures are constructed to restrict movement interfacially—wythe vs. wythe—along the z-axis and, in this embodiment, along the x-axis. The system 210 includes a masonry wall anchor 240 constructed for embedment in bed joint 226, which, in turn, includes a cavity-spanning or extension portion 242. Further, the system 210 includes a wire formative anchor member 244 for embedment in bed joint 230.
The components of the anchoring system 210 are shown in
Upon installation, the receptors 260 of T-head portion 258 is constructed to be within a substantially horizontal xz-plane normal to exterior surface 224. The receptor 260 is dimensioned to accept the tongue or bent portion of veneer anchor 244 and is slightly larger than the width of the tongue portion. This relationship minimizes the movement of the construct in an xz-plane.
The veneer anchor 244 is generally a bent box configuration and is dimensioned to be accommodated by the T-head receptor 260 of wall anchor 240 previously described. The veneer, anchor 244 has a tongue portion 262 with two parallel side leg portions 264 and connecting leg 266, and two cavity-spanning leg portions 268 contiguous therewith. The leg portions continue to an insertion portion and the insertion portion side legs 270 have been compressively reduced in height. The insertion portion is completed with front leg portions 271 and 273 which are spaced apart at least by the diameter of the veneer reinforcing wire member 275. An insertion portion 272 of veneer anchor 244, upon installation, extends beyond cavity 222 into bed joint 230, which insertion portion includes front leg portions 271 and 273 and side leg portions 270 adjacent to front leg portions 271 and 273, respectively. The longitudinal axes of leg portions 268, 270, 271, and 273 are substantially coplanar. The side leg portions 264 and connecting leg 266 are structured to function cooperatively with the spacing of the T-head 258 adjoining transverse wire members 254 to limit movement of the construct in the xz-plane.
The insertion portion 272 is considerably compressed and, while maintaining the same mass of material per linear unit as the adjacent wire formative, the vertical height 274 is reduced. The vertical height 274 of insertion portion 272 is reduced so that, upon installation, mortar of bed joint 230 flows around the insertion portion 272. Upon compression, a pattern or corrugation 276 is impressed on insertion portion 272 and, upon the mortar of bed joint 230 flowing around the insertion portion, the mortar flows into the corrugations 276. For enhanced holding, the corrugations 276 are, upon installation, substantially parallel to x-axis 234. In this embodiment, an indentation 278 is swaged into leg portion 270 opposite the opening between front leg portions 271 and 273, which indentation is dimensioned to accommodate veneer reinforcing wire 275. With the insertion end 272 of veneer anchor 244 as described, the wall anchor is characterized by maintaining substantially all the tensile strength as prior to compression while acquiring a desired low profile.
Referring now to
During the cold working of system components in addition to the swaged indentations, the insertion end of anchor 244 is compressively reduced in height. As described in a prior patent of the present inventors, namely, Hohmann et al., U.S. Pat. No. 6,279,283, the insertion ends of the veneer anchor is, upon cold-forming, optionally impressed with a pattern on the mortar-contacting surfaces. For this application, while several patterns—corrugated, diamond and cellular—are discussed in the patent, only the corrugated pattern is employed. The ridges and valleys of the corrugations are shown in
Because many varying and different embodiments may be made within the scope of the inventive concept herein taught, and because many modifications may be made in the embodiments herein detailed in accordance with the descriptive requirement of the law, it is to be understood that the details herein are to be interpreted as illustrative and not in a limiting sense.
| Number | Name | Date | Kind |
|---|---|---|---|
| 3377764 | Storch | Apr 1968 | A |
| 4021990 | Schwalberg | May 1977 | A |
| 4373314 | Allan | Feb 1983 | A |
| 4473984 | Lopez | Oct 1984 | A |
| 4869038 | Catani | Sep 1989 | A |
| 4875319 | Hohmann | Oct 1989 | A |
| 5392581 | Hatzinikolas et al. | Feb 1995 | A |
| 5408798 | Hohmann | Apr 1995 | A |
| 5454200 | Hohmann | Oct 1995 | A |
| 5456052 | Anderson et al. | Oct 1995 | A |
| 5634310 | Hohmann | Jun 1997 | A |
| 5816008 | Hohmann | Oct 1998 | A |
| 6209281 | Rice | Apr 2001 | B1 |
| 6279283 | Hohmann et al. | Aug 2001 | B1 |
