Abstract
A bathtub providing safe egress by reducing slide forces extended on a user's feet upon a slippery bathtub floor, has a limited rectangular footprint, and an optimized floor space is formed with a substantially planar base with a length and width that define the limited rectangular footprint and a front wall, a back wall, a first side wall and a second side wall integral with and extending substantially vertically upwards from the substantially planar base. Each of the front, back, first side wall and second side wall have minimal wall thicknesses to define the optimized floor space and the front wall has a substantially planar upper apron deck for a fixed amount in a substantially parallel relation to the substantially planar base.
Claims
1. A safe egress bathtub comprising: substantially vertical back and front walls, first and second end walls, and a flat bottom wall, all of said walls being of rigid material, entry and egress being over said front wall, said back wall abutting or is embedded in a room wall; said front wall having a cantilevered top horizontal apron deck extending from an outer surface of said front wall toward said back wall, said top horizontal deck consisting of a flat top surface and a distal free end cantilevered from the front surface of said top horizontal deck, extending inward and then rejoining a thin inner wall of the front wall where its inwardly undersurface curves backwards, said top horizontal deck having sufficient width to support sliding shower wall tracks thereon; said bottom wall extending to a rear, vertical surface of said front wall with said apron deck extending over said front wall extending cantilevered and overhanging an area of said bottom wall adjacent said rear, vertical surface of said front wall; and a thickness of said front wall and said apron deck are configured to obtain a straddle angle of egress over said front wall of said bathtub which is sufficiently small to minimize a horizontal component of force for reducing an incidence of slippage on a wet bottom and falling.
2. The bathtub of claim 1 in which said room wall has wall tiles thereon, said back wall having a top edge sufficient in thickness to accommodate bottom edges of said wall tiles.
3. The bathtub of claim 2 in which said top edge thickness of said back wall is about a quarter of an inch.
4. The bathtub of claim 1 in which the thickness of said front wall under said cantilevered top horizontal apron deck, is such as to reduce the horizontal component of force to less than about 14% of the weight of any user.
5. The bathtub of claim 1 in which said top horizontal deck has a width of up to a maximum of about 3.5 inches.
6. The bathtub of claim 1 in which other room walls abut said end walls of said bathtub leaving access and egress only over said front wall of said bathtub.
7. The bathtub of claim 1 in which said front wall has a thickness of about two and one half inches and said back wall has a thickness of about one inch.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) The present invention can best be understood in connection with the accompanying drawings. It is noted that the invention is not limited to the precise embodiments shown in the accompanying drawings, in which:
(2) FIG. 1 is a perspective view of a portion of a bathroom enclosing a prior art bathtub;
(3) FIG. 1A is a cross-sectional view of a prior art bathtub with a limited space interior;
(4) FIG. 2 is a perspective detail in partial crossection of a front corner of the prior art tub showing the front deck width;
(5) FIG. 3 is perspective view of a portion of a bathroom enclosing the bathtub of this invention;
(6) FIG. 4 is a perspective view of the bathtub of this invention;
(7) FIG. 5 is an end view crossection showing the profile of the cantilevered front deck;
(8) FIG. 5A is an end view crossection of an alternate embodiment, showing the profile of the cantilevered front deck;
(9) FIG. 6 is an enlarged cross-section detail of the cantilevered front deck;
(10) FIG. 7 is a side cross-section view of the bathtub of this invention;
(11) FIG. 8 is an end view profile of a prior art tub with rounded edges at bottom. An outline of the anchor leg of a person in unsupported egress is shown at a particular instant. Also shown is a vector force diagram at the same instant;
(12) FIG. 9 is an end view profile of the tub of this invention with an outline of the anchor leg of a person in unsupported egress at a comparable instant to that shown in FIG. 8. Also shown is a vector force diagram at the same instant.
(13) FIG. 10 is a top plan view of an alternate embodiment bathtub of this invention with a thicker front panel (without top cantilever) as shown;
(14) FIG. 11 is a side crossection view of the alternate embodiment of FIG. 10;
(15) FIG. 12 is a side exterior elevation view of the alternate embodiment;
(16) FIG. 13 is an end exterior elevation view of the alternate embodiment and,
(17) FIG. 14 is an end view profile of the alternate embodiment tub with an outline of the anchor leg of a person in unsupported egress at an instant comparable to that shown in FIGS. 8 and 9. A vector force diagram at the same instant is also shown.
DETAILED DESCRIPTION OF THE INVENTION
(18) As shown in Prior Art drawing FIGS. 1 and 2, the prior art tub 2 in bathroom 1 as shown in FIG. 1 is meant to represent any commonly available design. Front deck 3, back deck 4 and side decks 5 are shown. FIG. 2 is a close-up showing the typical wide dimension 8 of front deck 3 as well as the narrower side decks 5 dimension 7.
(19) FIGS. 3-9 pertain to one embodiment of the bathtub of this invention. The length of the bathtub can be from four to six feet, the height which could be from fourteen to eighteen inches, and the width which could be from thirty to thirty-six inches. FIG. 3 shows tub 15 in bathroom 10 which is of the same dimensions as bathroom 1 in FIG. 1, which is typically five feet wide (60 inches), thirty inches in front to back depth, and about fourteen inches in height. FIG. 4 shows tub 15 in a perspective view with back deck 17 in the forefront and front deck 16 at the far side. It is noted that side decks 18 as well as back deck 17 have wall widths that are equivalent to the thickness or width of the material comprising the side walls, the back wall and the front wall below the front deck. The crossectional views of FIGS. 5, 5A and 6 show the cantilevered shape of front deck 16 in detail, highlighting that the front deck width does not encumber the interior width of the tub floor. It is further noted that the width dimension 19 is the same as dimension 8 in prior art FIG. 2. FIG. 7 is a length wise crossection showing sloping backrest 20 and slight drain slope 21, which is preferred. In these FIGS. 3-9, large sections are shown as being solid material just for interior dimensional clarity, however they may in fact have enclosed air spaces. This would be especially true of the large wedge shape under back rest 20 and the cantilevered front deck as in FIG. 6; it would depend on the material used and method of construction.
(20) An expanded space bathtub 15 fits in standard tub dimensions of bathroom 10 having footprint floor area 10a and vertically extending bathroom wall surfaces 10b, 10c and 10d, and has a larger internal floor area 15e of bottom base wall 15f, and larger air volume 30 within. The bathtub 15 includes thin walls, including four vertically extending walls, including front wall 15a, rear wall 15b, left side wall 15c with sloping backrest 20 adjacent thereto and separated from left side wall 15c by hollow interior area 21a, and right side wall 15d having trip lever hole 23. Vertical walls 15a, 15b, 15c and 15d extend vertically upward from rectangular bottom base wall 15f having an exterior footprint to fit within the pre-determined rectangular bathtub insertion floor footprint area 10a of bathroom 10. Bottom base wall 15f has an interior footprint 15e, which, with the inside surfaces of vertically extending walls 15a, 15b 15c and sloping backrest wall 20 of left side wall 15c, define the enlarged air volume 30 extending therebetween.
(21) The thickness of the vertical walls 15a, 15b, 15c, 15d and sloping side backrest 20 is preferably one inch in thickness near the top, up to about one and one quarter inches on the bottom, to provide a slightly sloped surface for easy removal of the tub from a mold. The one inch and one and one quarter inch dimensions need not be solid, so that a wall (not shown) having a thickness of one quarter inch on each side can have a hollow interior of one half inch. A similar hollow area can be provided at the slightly wider bottom width of one and one quarter inches total, combined with the walls and hollow interior. Moreover, for the rear, wall facing wall 15b, the wall 15b can be just one layer of one quarter inch in thickness, with a three quarter inch hollow area behind the one quarter inch wall, up to the bathroom wall surface 25 itself. The one inch thickness at the top 17 of rear wall 15b is required to accommodate tiles of up to inch in thickness and accompanying grout against the bathroom wall surface 25. As shown in FIG. 5A, an optional attachment flange 24 can be attached to rear wall 15b for attachment to bathroom wall surface 25.
(22) As shown in the crossectional view of FIG. 7, the inside bottom footprint 15e of bottom base wall 15f preferably has a slope 21, sloping downward from the corner 21a defined by sloping backrest 20 and an adjacent edge of interior footprint 15e of bottom base wall 15f, downwards towards water drain hole 22.
(23) In the cantilevered apron deck embodiment of FIGS. 3-9, the front apron deck 16's width of up to a maximum of 3.5 inches is maintained within normal construction requirements to support the sliding glass door tracks, but without the need for limiting interior bathtub volume with thick walls. The cantilevered apron deck 16 can also have a reduced width of about two and one half inches. The side decks 18 and back deck 17 are limited to the thickness of the tub material. In the embodiment of FIGS. 3-9, the front apron deck 16 has a width which is maintained to industry standards to support sliding shower wall tracks thereon, but it is cantilevered from the front surface of front wall 15a inward and then rejoins the thin inner wall of the front wall 15a where its inwardly preferably curved backwards undersurface wall 16a meets near the top of the inner surface of front wall 15a of bathtub 15, thereby not reducing the interior floor space 15e or the interior air volume 30 by the front deck 16's width. The bathtub 15 therefore maximizes internal bathtub/shower stall space within the predetermined confines of typical residential bathroom bathtub and shower space dimensions.
(24) The bathtub 15 of this invention can be made of steel or plastic resin materials and finished as is common in the industry.
(25) A comparison of the interior floor space and enclosed air volume (to the top edge of all four vertical walls the tub) has been made to compare a prior art tub and a tub of FIGS. 3-9 of this invention of the same external dimensions. A prior art front deck of 4 and a back deck of 3 with side decks of 2 in a 60 inch external length by 30 inch tub of 15 average internal depth was assumed for comparison. The wall thickness of the tub of this invention is assumed to be 1. Both tubs have the angled backrest and straight vertical walls. The increased floor area and air volume in the tub of this invention is due to the 1 wall thickness and decks (on 3 edges) vs. the decks of the prior art tub which reduce the internal dimensions.
(26) The results of the comparison are as follows:
(27) Interior Floor Area prior art 1120 sq. in. this tub 1419 sq. in., a 27% increase.
(28) Interior Air Volume prior art 16790 cubic in. this tub 20845 cubic in., a 24% increase
(29) Additionally, the above calculations were based upon a prior art bathtub with a front deck of 4 and a back deck of 3 with side decks of 2 in a 60 inch external length by 30 inch tub of 15 average internal depth for comparison. However, since most prior art tubs have sloping and bottom rounded sides, the numbers of this estimate represent the minimum percentage increases in interior floor area and interior volume. It is estimated that in comparison with other prior art bathtubs, with increased sloping and bottom rounded sides, the savings can be up to approximately 35% increase in interior floor area and interior air volume.
(30) Bathtub 15 of this invention also offers safety improvement over that of the prior art. Safety studies indicate over 234,000 bathroom injuries each year, of which 81 percent occurred because of falls in the bathroom. Of these injuries, more than one third happen while bathing or showing. The Center for Disease Controls (CDC) estimates that 9.8 percent of all bathroom injuries specifically occur when getting out of a bathtub, which equals at least 22,932 injuries.
(31) FIG. 8 shows a profile of a person 42 exiting a prior art bathtub 40 with rounded walls at the bottom. The average person 42 is a composite 50.sup.th percentile man or woman with a hip joint to floor dimension L of 35 inches. Although the results of the analysis to follow are somewhat dependent on this selected number, let it be said that a taller person would experience slightly less difference in egress from either a prior art tub or the tub 15 of FIGS. 3-9 of this invention, and vice versa for a shorter person. Note that the rounded side bottom edge forces the anchor foot farther away from the front edge of the tub (toward the middle) to be supported by the flat portion; this is also true of prior art profile shown in FIG. 1A with the sloping sides.
(32) The instant for the static analysis of FIG. 8 is that corresponding to the hip joint being directly above the front edge of the tub with the ball of the anchor foot carrying the entire weight of the person before the forward foot (not shown) touches the ground. For the purpose of analysis, the anchor leg can be represented by a rigid rod from the hip joint 44 to the ball of the anchor foot. By measuring the angle in FIG. 8, it is found that this rod makes a 17 degree angle with the vertical as shown in the vector force diagram to the right. The weight of person 42, W, is shown vertically. The horizontal component force Fs that arises from this arrangement is 0.306 W or almost 31% of the weight of the person. This horizontal component must be resisted by the frictional force between the ball of the anchor foot and the tub (or a tub mat). Several items affect the local coefficient of friction between foot and tub, or foot and mat and mat to tub. Water, and especially soapy water, is a good lubricant and dramatically reduces the coefficient of friction. If the anchor foot slips, the bather is in trouble!
(33) If a similar analysis of Applicants' expanded space tub 15 is performed as depicted in FIG. 9, the angle of rigid rod and the vertical is only 5.5 degrees because now the anchor foot is so close to the front edge. The horizontal component force Fs that results in this analysis is 0.096 W or only less than 10% of the weight of the person. Thus with the same bather exiting either a prior art tub or a tub 15, slippage can be avoided in a tub 15 of this invention even if the friction coefficient were of that which minimally prevented a spill in a conventional tub. Common sense reinforces the numeric example; the tub 15 side walls are substantially vertical; the bather can have the planted leg being substantially vertical and stable, and this requires only lifting the leading leg up and over the thin apron of 3.5 inches or less.
(34) An alternate embodiment tub 50 of this invention is the subject of FIGS. 10-14. This tub is similar to tub 15 of this invention, but uses a front panel of thicker material instead of a top cantilever to provide the top resting surface to receive door tracks (if used).
(35) FIG. 10 is a top view showing a front panel 52 of about 2.5 in thickness. It is noted that the 2.5 thickness can be reduced down from 2.5 in a range of to a top thickness of about one inch. Other dimensions shown in FIGS. 10, 11, 12, and 13 include the length which could be from four to six feet, the height which could be from fourteen to eighteen inches, and the width which could be from thirty to thirty-six inches. The side crossection of FIG. 11 reveals that it is identical in shape to that of FIG. 7 for tub 15.
(36) The side profile of FIG. 14 showing the front panel 52 in crossection more clearly shows the distinction from tub 15 with it's cantilever at the top edge (see FIG. 9). FIG. 14 is an egress analysis of person 42 exiting the alternate embodiment tub 50 as was performed before for the prior art, and for tub 15 of this invention. Again, dimension L of a rod from hip joint 44 to the ball of the foot is 35. In this case however, the rod makes an angle of 7.97 degrees with the vertical as opposed to 17 degrees for the prior art situation or 5.5 degrees for tub 15. In tub 50, person 42's foot is forced slightly back (1.5) from the front surface relative to the position in tub 15 due to the thicker front panel 52. This geometry results in a side force (Fs) of 14% of the person's weight, W. While this is not as safe as the case for tub 15, this is still less than half the side force of the prior art tub (31% of the person's weight) analysis of FIG. 8.
(37) In the foregoing description, certain terms and visual depictions are used to illustrate the preferred embodiment. However, no unnecessary limitations are to be construed by the terms used or illustrations depicted, beyond what is shown in the prior art, since the terms and illustrations are exemplary only, and are not meant to limit the scope of the present invention.
(38) It is further known that other modifications may be made to the present invention, without departing the scope of the invention, as noted in the appended Claims.
