MECHANISM FORTOlLET SEAT

FIELD OF THE INVENTION The present invention relates to the field toilet seats and toilet pans. More particularly, the present invention relates to mechanisms for raising and maintaining a seat plate of a toilet seat assembly at a required angular position.

BACKGROUND OF THE INVENTION

It may be desirable to maintain the seat plate of a toilet seat assembly in a substantial vertical or upright position when it is not in use for hygiene and cleaning purposes, in particularly in public toilets. Spring biased seat assemblies for returning the seat plate to the required position have been previously provided, as well as various improvements thereof. For example, US patent No.4,402,092, 2 October 1981 , discloses the uses of a slip clutch to slow the angular rotation of the seat plate to its spring-biased position.

It is an object of the present invention to provide a toilet seat assembly which overcomes or substantially ameliorates at least some of the deficiencies exhibited b those of the prior art.

SUMMARY QF THE INVENTION

According to an aspect of the present invention, there is provided a mechanism for returning a seat plate to a predetermined raised angular position relative to a toilet bowl, the mechanism including: a rotatable shaft mountable to a toilet bowl such that upon lifting and lowering of a seat plate the shaft is rotated; a first biasing means for urging the seat plate from a. lowered position towards the desired angular position; and

a pawl engageable with the rotatable shaft as the pivot shaft is urged by the first biasing means to rotate in a first direction for moving the seat plate from a lowered position towards the desired angular position, wherein the seat plate is maintained in a lowered position for a predetermined period of time until the pawl is disengaged from the rotatable shaft..

According to a second aspect of the present invention, a toilet seat assembly, comprising a seat plate; and a biasing mechanism for returning the seat plate to a desired angular position relative to the toilet seat, including: a rotatable shaft mountable to a toilet bowl such that upon lifting and lowering of the seat plate the shaft is rotated; a first biasing means for urging the seat plate from a lowered position towards the desired angular position; and a pawl engageable with the rotatable shaft as the pivot shaft is urged by the first biasing means to rotate in a first direction for moving the seat plate from a lowered position towards the desired angular position, wherein the seat plate is maintained in a lowered position for a predetermined period of time until the pawl is disengaged from the rotatable shaft.

Preferably, the toilet seat includes a mechanism for automatically sterilizing the seat plate when the seat plate returns to the desired angular position.

Other aspects and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the

accompanying drawings, which description illustrates by way of example the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example only, and with reference to the accompanying drawings in which:

Figure 1 shows a side view of an exemplary embodiment a toilet seat according to an present invention and a water tank whereby the cover plate is depicted in a vertical position and the seat plate is depicted, in a substantially horizontal position;

Figure 2 is a top plan view of the toilet seat of figure 1 with the cover plate and seat plate being depicted in a closed position;

Figure 3 is a part sectional side view of the toilet seat of figure 1 depicting a portion of a biasing mechanism according to the present invention;

Figure 4 is an enlarged partial spot sectional view showing the cover plate, the seat plate and portion of the biasing mechanism;

Figure 5 is a perspective view part of a portion of the biasing mechanism of figure 4;

Figure 6a is a top plan view showing a portion of the biasing mechanism of figure 4 and figure 5;

Figure 6b is a plan view illustrating the exterior of the biasing mechanism;

Figure 7a is a cross-section view along line E-E' of the biasing mechanism of figure 6b;

Figure 7b is a cross-section view along line F-F' of the biasing mechanism of figure 6b;

Figure 8a is an enlarged side view of a pawl of and a retention cam of the biasing mechanism of figure 7b;

Figure 8b is an exploded view of the pawl and the cam of figure 8a;

Figure 9 is a simplified elevation view of the toilet seat of figure 1 , illustrating the rotational range of the seat plate between the opened and closed positions;

Figures 10a, 10b and 10c progressively illustrate the relationship between the pawl and cam of figures 8a and 8b when the seat plate is rotated from the substantially vertical position to the horizontal position; and

Figures 11 a, 11 b and 11 c progressively the relationship between the pawl and cam of figures 8a and 8b when the seat plate is rotated from the horizontal position to the substantially vertical position.

DETAILED DESCRIPTION OF THE INVENTION

The following description refers to preferred embodiments of a toilet seat assembly according to the present invention. To facilitate an understanding of the invention, reference is made in the description to the accompanying drawings whereby the adapter is illustrated in preferred embodiments. Similar components between the embodiments are identified by the same reference numerals.

Figure 1 illustrates an exemplary embodiment toilet seat assembly 100 according to the present invention, and a cistern 101 generally in use with a toilet 100. The toilet 100 generally stands on the floor 103 with the cistern 101 is generally aligned with the wall 105. The toilet 100 generally has a toilet bowl 107, a seat plate 109 and a cover plate 111 both atop the toilet bowl 107 as will be understood by a person in the art. Both the seat plate 109 and the cover plate 111 are individually pivotably mounted to the toilet bowl 107, and thereby both can independently rotate between a generally horizontal position 115 and a generally vertical position 117.

Figures 2, 3 and 4 illustrate both the seat plate 109 and the cover plate 111 in the horizontal position 115. As shown in figures 2, 3 and -4, suction rubber dampers 301 are attached to a bottom of the seat plate 109 and in contact with the toilet bowl 107 when the seat plate 109 rests on the toilet bowl 107 in the horizontal position for temporarily preventing the seat plate rising up. In addition, as shown in figures 3 and 4, part 405 of bottom of the cover plate 111 facing the seat plate 109 is modeled in a same configuration as the seat plate 109 for catering the same. Replaceable self-adhesive sterilization paper towels are attached to said part 405 of the bottom of the cover plate and can be in contact with the seat plate 109 for automatic sterilization of the seat plate 109.

The cover plate 111 is pivotably mounted to a primary shaft 401 through a cover plate hanging arm 201; the seat plate 109 is secured to the primary shaft 401 through a seat plate hanging arm 203 and a pair of screws 205 so that rotation of the seat plate 109 between the vertical and horizontal positions causes rotations of the primary shaft 401 as well.

The primary shaft 401 is pivotably or rotatably mounted to a pair of brackets (not shown) projecting from the toilet bowl 107 as will be understood in the art.

A retention box 207 is also mounted to the primary shaft 401 for housing a spring mechanism 501 (see figure 5).

As shown in figures 5 to 8, the biasing mechanism 501 is provided in the retention box 207 for automatically raising the seat plate 109 from the horizontal position to the vertical position. The primary shaft 401 passes through a pair of walls 503 of the retention box, and as the seat plate 109 is rotated to the horizontal position for use, rotation of the primary shaft 401 is transmitted to a secondary shaft 505 through a pair of gears 507, 509 mounted to the primary and secondary shafts 401 , 505 respectively, A torsion spring 511 , with one end mounted onto one of the walls 503 and the other end mounted to the secondary shaft 505, is tensioned as the seat plate 109 is rotated towards the horizontal position in a manner such that the spring force of the torsion spring 511 biases, through the primary and second shafts 401 , 505 and the gears 507, 509, the seat plate 109 towards the vertical position, thus causing the seat plate to be urged to the vertical position in the absence of any constraint.

A pair of retention pawls 601 is provided in the retention box to interact with a pair of corresponding retention cams 603 mounted to the secondary shaft 509 for temporarily holding the secondary shaft 509 stationary for a suitable period of time. Through such a mechanism, as a user leaves the seat plate, the seat plate is held in its horizontal position for a suitable period of time before it is driven to the vertical position by the torsion spring. Each pawl 601 is pivotably mounted to a bracket 807 in the retention box through a fastener passing though a hole 805 thereon and a corresponding nut 803. One end 701 of the pawl 601 , relatively distanced from a pivot point 703, is connected to an end of a tension spring 705, the other end of which is mounted to the bottom 707 of the retention box 207. The other end 709 of the pawl 601 , relatively closer to the pivot point 703, provides a relatively steep retention surface 809 on one side for engaging a mating engaging surface 811 of a projection 813 provided

on the engaging cam 603. The other side of end 709 provides a curved surface 815, which can be in smooth contact with the engaging cam 603.

Operation of the spring mechanism 501 is described as follows. When the toilet seat is in use, the cover plate 117 is generally in a vertical position, and the seat plate is rotated to a horizontal position. During such rotation, the torsion spring 511on the secondary shaft 507 is biased. As the user leaves the seat plate 109 and the seat plate 109 is unrestrained , due to the spring force of the torsion spring 511 , the secondary shaft 505 is rotated in a counter-clockwise direction as indicated by arrow S' in figure 8a. Rotation of the secondary shaft 505 in direction S' drives the seat plate to rise up to its vertical position. In the beginning of the rising up of the seat plate, as the engaging surface 811 comes into engagement with the retention surface 809 as shown in figure 8a, due to the spring force of the tension spring 705, the secondary shaft 505 is held in this position temporarily for a period of time until the engaging surface disengages the retention surface. As such, rising- up of the seat plate is temporarily prevented..

The torsion spring 511, the tension spring 705 and the lever system 701 provided by the pawl 601 are configured such that the spring force of the torsion spring 511 will overcome the spring force of the tension spring 705 so that the retention cam 603 further pushes down end 709 of the pawl 601 until they disengage from each other. Thereafter, without the constraints by the pawl 601 , the torsion spring 511 further rotates the secondary shaft 505 in the S' direction and consequently lifts up the seat plate.

With reference to figures 9, 10a, 10b and 10c and figures 11a, 11 b and 11c, interaction between the pawl 601 and the cam 603 during various stages when the seat plate is rotated in the clockwise and counter-clockwise directions are described as follows,

In the exemplary embodiment, the ratio of the numbers of the teeth of gears 507, 509, which are mounted to the primary and second shafts 401, 505 respectively, is 3:1 so that as the primary shaft is rotated by 100 degrees, the second shaft is rotated by 300 degrees, and vice versa.

As shown in figure 9, in the exemplary embodiment, the seat plate 109 is rotated by approximately 100 degrees as it is rotated between the horizontal position and the substantially vertical position. Therefore, the secondary shaft 505 will be rotated by 300 degrees during such rotation.

Figure 10a illustrates the angular positions of the cam 603 and the pawl 601 when the seat plate 109 is in its substantially vertical position and is in contact with a sterilization paper towel for sterilization. A virtual horizontal line "A," passing through the center 1001 of the second shaft 505, is used for reference. The pawl 601 extends at least substantially horizontally. A virtual line 1003, passing through the center 1001 and end 709 of the pawl 601, extends at approximately 45-60 degrees relative to reference line "A." Virtual line 1005, passing through the engaging surface 811 and the center 1001, extends at approximately 30r45 degrees relative to reference line "A." Clockwise, lines 1005 and 1003 extend at approximately 290 degrees.

During rotation of the seat plate 109 from its substantially vertical position to the horizontal position, when the secondary shaft 505 has been rotated clockwise as shown by arrow 1007 by approximately 290 degrees, the projection 813 comes in contact with curved surface 815 of the pawl and thereby pushes the pawl to rotate counter-clockwise and spring 705 is compressed.

As the seat plate 109 is rotated further to its horizontal position, the engaging surface 811 passes the pawl 601 to a position slightly above the pawl 601 when the secondary shaft 505 has been rotated by 300 degrees. Due to a

clearance between the pawl 601 and the cam 603 (not shown) and the spring force of the spring 705, the pawl 601 returns to its balanced position, in which the pawl extends substantially horizontally.

Figures 11 a, 11 b and 11 c illustrate the automatic rotation of the seat plate 109 from its horizontal position towards its substantially vertical position. In the beginning, as shown in figure 11a, as the secondary 505 shaft has been rotated counter-clockwise indicated by arrow 1101 by approximately 10 degrees, i.e., when the seat plate is rotated upwards by approximately 3 degrees from its horizontal position, the engaging surface 811 comes into contact with end 7-9 of the pawl 601. Such engagement holds the secondary shaft 505 in this position temporarily for a period of time.

Due to the spring force of the. torsion spring 511 , the engaging surface 811 pushes down the pawl 601 as shown in figure 11b until they disengages each other. Afterwards, as shown in figure 11c, the secondary shaft 505 further rotates counter-clockwise to its balanced position of figure 10a. During such rotation, as shown in figure 11c, the pawl 601 may be in contact with the external surface of the cam 604 and thereby exerts a friction force thereon. The spring mechanism is configured to minimize the effect by such friction force so that the seat plate 109 is rotated to its vertical position smoothly.

Furthermore, When the seat plate is lifted to its vertical position, it becomes in contact with the sterilization paper towel so that automatic sterilization is achieved.

It will be understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention. The foregoing describes an embodiment of the present invention and

modifications, apparent to those skilled in the art can be made thereto, without departing from the scope of the present invention.

Although the invention is illustrated and described herein as embodied, it is nevertheless not intended to be limited to the details described, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.

Furthermore, it will be appreciated and understood that the words used in this specification to describe the present invention and its various embodiments are to be understood not only in the sense of their commonly defined meanings, but also to include by special definition in this specification structure, material or acts beyond the scope of the commonly defined meanings. Thus, if an element can be understood in the context of this specification as including more than one meaning, then its use in a claim must be understood as being generic to all possible meanings supported by the specification and by the word itself. The definitions of the words or elements of the following claims are, therefore, defined in this specification to include not only the combination of elements which are literally set forth, but all equivalent structure, material or acts for performing substantially the same function in substantially the same Way to obtain substantially the same result, without departing from the scope of the invention.