Device for reducing wave motion in a waterbed mattress

A device for reducing the wave motion in a waterbed mattress which provides optimum firm and conforming feel to the user, while not promoting fungi or algae growth and being capable of allowing the mattress to be substantially completely drained. The wave motion reducing device comprises at least one compartment including a top wall, a bottom wall, and a marginal perimeter wall interconnecting the top wall and the bottom wall to form an enclosed chamber. The bottom wall and the marginal perimeter wall respectively define at least one opening therethrough, the opening being of a dimension to enable a minimum fluid flow into and out of the chamber and inhibit transient fluid flow into and out of the chamber. A buoyant insert is operatively connected to the top wall to urge the compartment toward the top of such bladder. The buoyant insert includes a member having a plurality of uniformly sized air entrapping cells. The cells serve to constantly urge the compartment toward the top surface of the mattress and do not interact with the water so that fungi and algae growth are prevented.

BACKGROUND OF THE INVENTION 
This invention relates in general to a device for reducing wave motion in 
waterbed mattresses, and more particularly to a wave reducing device of 
the hydraulic chamber type having a bouyant insert to locate the hydraulic 
chamber for optimum wave motion reduction. 
Floatation sleep systems, commonly referred to as waterbeds, have become a 
popular alternative to conventional bedding due to their ability to give a 
more comfortable and relaxing sleep. This superior sleep is attributable, 
at least in part, to the substantially uniform pressure distribution 
exerted on the body when lying on the surface of the waterbed mattress. 
However, historically, objections to waterbeds have been based primarily 
on their propensity for extensive surface movement when a body supported 
on the mattress bladder changes position. The extensive movement is due to 
reflected wave action of the water within the bladder, initially induced 
by the changing of the location of displacement when the supported body 
moves on the surface of the bladder. Recent attempts to reduce wave motion 
have included utilizing a filler material, such as fiber and foam for 
example, within the bladder of the waterbed mattress. Such material has 
certain drawbacks which make their use less than desireable. Specifically, 
the fiber and foam react with the water to promote the growth of fungi and 
algae, and further they retain water so that complete draining of the 
bladder is not possible. 
Another mechanism by which reduction of wave motion has been attempted is 
the inclusion of a device within the bladder which acts as a baffle to the 
flow of water within the bladder. One particularly effective baffle device 
is typically referred to as an hydraulic chamber. The hydraulic chamber 
comprises a compartment having a plurality of ports for allowing the water 
to move in and out of the compartment. The ports are of sufficient size to 
enable the water to move relatively freely into and out of the 
comparrtment when the mattress bladder is filled or drained, but restricts 
rapid transient flow of water induced by movement of a body supported on 
the surface of the mattress. 
An example of a typical hydraulic chamber is shown in U.S. Pat. No. 
4,607,404 (issued Aug. 26, 1986, in the name of Fraige). The hydraulic 
chamber of such patent includes a buoyant insert of interbonded, non-woven 
polyester fiber. The bouyant insert serves to float the top of the chamber 
just below the top surface of the mattress with the chamber hanging 
downwardly toward the bottom of the mattress. Such location of the 
chamber, enables the top surface of the mattress to exhibit a desireable 
feel to a body supported on the mattress. However, hydraulic chambers with 
buoyant inserts of this construction take time to stabalize against the 
top surface of the mattress when subjected to body movement on the 
surface, and further are subject to the above noted disadvantages of fiber 
in the water environment of the waterbed mattress. 
SUMMARY OF THE INVENTION 
This invention is directed to a device for reducing the wave motion in a 
waterbed mattress which provides an optimum firm and conforming feel to 
the user, while not promoting fungi or algae growth and being capable of 
allowing the mattress to be substantially completely drained. The wave 
motion reducing device comprises at least one compartment including a top 
wall, a bottom wall, and a marginal perimeter wall interconnecting the top 
wall and the bottom wall to form an enclosed chamber. The bottom wall and 
the marginal perimeter wall respectively define at least one opening 
therethrough, the opening being of a dimension to enable a minimum fluid 
flow into and out of the chamber and inhibit transient fluid flow into and 
out of the chamber. A buoyant insert is operatively connected to the top 
wall to urge the compartment toward the top of such bladder. The bouyant 
insert includes a member having a plurality of uniformly sized air 
entrapping cells. The cells serve to constantly urge the hydraulic chamber 
toward the top surface and do not interact with the water so that fungi 
and algae growth are prevented. 
The invention, and its objects and advantages, will become more apparent in 
the detailed description of the preferred embodiments presented below.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the accompanying drawings, the device for reducing wave 
motion in a waterbed mattress according to this invention is designated 
generally by the numeral 10. As best shown in FIG. 1, the device 10 
includes a plurality of interconnected hydraulic cylinders 12 located 
within the interior of a waterbed mattress 14. The hydraulic cylinders 12 
are constructed as a unit having a common top sheet 16 formed of a 
flexible, substantially dimensionally stable material such as polyethelene 
or polyvinylchloride for example. 
Each of the hydraulic cylinders 12 are of the same configuration, and as 
such, the detailed construction of only one cylinder is herein shown and 
described, with the remaing cylinders being of substantially identical 
construction. In FIG. 2, a first preferred embodiment of the hydraulic 
cylinder 12 is shown as including a bucket portion 18 connected to the top 
sheet 16. The bucket portion 18 is preferrably formed of the same material 
as the top sheet so that the interconnection of the bucket portion to the 
top sheet can be accomplished by heat sealing for example. Of course, the 
material of the bucket portion may be of a different material from that of 
the top sheet, with the interconnection being effected in any other well 
known manner such as by riveting or gluing for example. The bucket portion 
18 has openings 20 respectively formed in the marginal side walls, and an 
opening 22 formed in the bottom wall. The openings are of a particular 
size so as to enable substantially unrestricted water movement into and 
out of the bucket portion when the mattress 14 is filled or drained, and 
yet restrict a more rapid water flow due to transients generated by the 
movement of a body on the top surface of the mattress. In this manner the 
bucket portion 18 will act to dampen wave motion in the water of the 
mattress caused by such body movement. 
In order to maintain the bucket portion 18 in substantially constant 
effective contact with the top surface of the waterbed mattress 14, the 
hydraulic cylinder 12 includes a buoyant insert member 24. The buoyant 
insert member 24 is securred in place against the bottom side of the top 
sheet 16 by a retaining sheet 26. The retaining sheet 26 is also 
desireably formed of the same material as the top sheet so that it can 
similarly be joined to the top sheet and bucket portion by heat sealing 
for example. Of course it is contemplated by this invention that the 
buoyant insert member 24 could be formed of the same material as that of 
the top sheet 16 so that the member 24 could be directly joined to the top 
sheet and bucket portion by heat sealing for example. The top sheet 16, 
Buoyant insert member 24, and retainer sheet 26 respectively have openings 
16a, 24a, and 26a aligned to provide a restricted water flow passage into 
and out of the bucket portion 18 through the top thereof. This passage 
allows air to escape from the bucket portion 18 when the mattress 14 is 
first filled, and a limited amount of water to flow over the top of the 
top sheet 16 when the cylinder 12 is forced downwardly by a body on the 
surface of the mattress 14 to further dampen the wave motion within the 
mattress. 
The buoyant insert member 24 is a sheet of air encapsulating cellular 
material. As shown, the cellular material has a plurality of uniformly 
sized cells of substantially hemispherical shape with the apexes of the 
cells directed toward the top surface of the mattress. Of course, other 
configurations of cells for the cellular material, such as elongated tubes 
for example, are suitable for use with this invention. The cellular 
material is of a highly buoyant nature and will accordingly act constantly 
to urge the the hydraulic cylinder 12 upwardly toward the desired contact 
with the top surface of the mattress 14. Even direct application of a 
downward force due to a body located directly over the particular cylinder 
will not substantially cause the cylinder to move away from the top 
surface of the mattress. Thus, the body supported on the mattress will 
always perceive a firm yet body-conforming feel. This is the most 
desireable surface feel for inducing optimum sleep. Moreover, due to the 
fact that the material of the buoyant insert 24 is nonabsorbing yet fully 
compatible with water, no fungi or algae growth will be promoted. Also, 
this non absorbing quality will enable the mattress to be substantially 
fully drained when desired. 
In the alternate embodiment of the hydraulic cylinder according to this 
invention shown in FIG. 3, a layer of closed cell foam 30 is attached to 
the buoyant insert member 24. This closed cell foam 30 provides an 
enhanced degree of rigidity to the hydraulic cylinder whereby the overall 
surface of the device 10 is more uniform. In the alternate embodiment of 
the hydraulic cylinder according to this invention shown in FIG. 4, an 
additional layer 40 of the air encapsulated cellular material is attached 
to the top surface of the top sheet 16. The individual cells of this 
additional layer 40, maintained in contact with the top surface of the 
mattress 14 due to their bouant nature, serve to give an enhanced feeling 
a body-hugging conformity to the body supported on the mattress. 
FIGS. 5 and 6 show a further embodiment of the device for reducing wave 
motion, designated by the numeral 10'. The device 10' includes a hydraulic 
cylinder unit containing a number of interconnected hydraulic cylinders 
12', of any of the types described above with reference to FIGS. 2-4. 
However, in this embodiment the perimeter of the hydraulic cylinder unit 
has a tube 50 connected thereto. The tube 50 is formed of the same 
material as the top sheet 16' of the hydraulic cylinders 12' so that it 
can be joined to the top sheet by heat sealing for example. Of course, the 
tube 50 could be connected to the top sheet 16' by any other well known 
mechanisms such as gluing or stapling for example. 
The tube 50 is adapted to be pressurized, with air for example, so as to 
maintain its tubular configuration when the device 10' is located in a 
fluid-filled waterbed mattress. For example, the tube may have an umbilcal 
cord 52 accessable through the mattress fill valve 54. At the appropriate 
time (when the mattress is filled with fluid), the tube 50 can be 
pressurized by being connected to a pressurized air source. Of course, the 
tube could alternatively be filled with a material, such as foam for 
example, the only requisite being that the material is buoyant to 
accomplish the described functions for the tube. 
When the tube is pressurized, it serves to maintain the device 10' in 
proper orientation within the mattress so that the hydraulic cylinders 12' 
are located (and fillable with fluid) for effective operation. Further, 
the tube 50 serves as an edge perimeter support for the mattress such that 
the mattress has a highly desireable feel to the user, with or without the 
mattress being located within a rigid frame. This arrangement facilitates 
the use of a pair of mattresses in side-by-side relation for a dual 
assembly, in that the tube sections in juxtaposition with the adjacent 
perimeter walls of the mattresses support the mattresses at the center for 
comfortable support of the user on each mattress. Additionally, a single 
mattress could contain a pair of wave reducing devices with the associated 
tubes to support the center of the mattress in a similar manner as the 
described dual mattres arrangement. 
The invention has been described in detail with particular reference to a 
preferred embodiments thereof, but it will be understood that variations 
and modifications can be effected within the spirit and scope of the 
invention.