VANDAL RESISTANT PUSH-PULL DRAIN STOPPER

Abstract: In a vandal resistant push-pull drain stopper for use with a drain plug (44) of a bath or other similar vessel, there is provided a plunger (46) having an inner cylindrical bore, a stem (10) having a reduced portion (24), an expanded portion (55) and a channelled portion (16), an O-ring (18) snugly nestled between the plunger (46) and the stem (10); a cap (34) threadably engaged with the plunger (46) and axially disposed about the upper region of the stem (10) the cap (34) having a relief (A) inside the hexagonal bore (B) portion thereof so that the plunger (46) freely rotates about the cap (34) by discouraging removal of the cap (34) from the drain plunger (46); the plunger (46) having a seal (38) so that when the plunger (46) is in a closed position the seal (38) abuts with the outer periphery of the drain plug (44) thereby sealing the same. The reduced (24) expanded (55) and channelled (16) portions of the stem (10) permit the drain plug (44) to be open and closed by user and provide tactile "snap in place feel" in the open and close positions while employing only, essentially, two moving parts.

Description: The present invention relates to drain stoppers, more particularly to a push-pull vandal resistant drain stopper for baths or other similar vessels. Different types of drain stoppers have been developed over several years. For example, drain stoppers having a complicated lever action, in which the lever which opens and closes the drain stopper is located in close proximity to the spout of the bathtub, are well known in the prior art. However, such drain stoppers have serious drawbacks in that the stopper is removable from the linkage mechanism of the lever, thereby encouraging vandalism in hotel bathrooms and other locations to which the public have access, and also, the linkage mechanism from the lever to the stopper often breaks and is complicated and expensive to manufacture. In order to overcome the drawbacks associated with such lever drain stoppers, various prior art drain stoppers, for example those disclosed in GB Patent no. 2,177,908, have been developed which do not require a lever ard which may be opened and closed by applying pressure to the stopper so that, in response to either rubber or spring biassing, the drain stopper pops up to open or compresses to close. The disadvantage of such prior art drain stoppers is that the springs often wear with use and create an ineffective seal. Furthermore, such prior art drain stoppers require complicated cam-shaped parts having interlocking mechanisms which may eventually wear and malfunction and are expensive to machine and manufacture. Other prior art stoppers are of the lift and turn type which are confusing because the direction of turning is not obvious. Also they require components that are costly to manufacture. Most non-lever operated stoppers that are wholly contained within the drain of a bath are prone to theft since they may be readily removed from the drain. Various attempts have been made to deter theft and vandalism of drain stoppers. U.S. Patent no. 4,369,531 discloses a drain stopper having a spring biased plunger. This stopper assembly is secured to the drain body (sometimes referred to in the plumbing fixture industry as a drain plug or spud) so that it cannot be removed from the body without removing the body from the bath. While this stopper is thus inherently vandal resistant, it is difficult to service or replace. A tamper resistant push-pull type of stopper is disclosed in U.S. Patent No. 4,720,877. In order to remove this stopper from a drain on which it is installed, a knob portion of the stopper must first be removed to provide access to a central post which secures the stopper assembly to the drain plug. It is an object of the present invention to provide a vandal resistant push-pull drain stopper in which the above disadvantages are reduced or substantially obviated. The present invention provides a vandal resistant push-pull drain stopper for use with a drain plug of a bath or other similar vessel, which drain stopper comprises a plunger having a generally cylindrical bore; a stem threadably coupled to the drain plug and coaxially disposed within the generally cylindrical bore of the plunger; movement regulating means for regulating the axial movement of the plunger; and sealing means disposed peripherally about the plunger for sealing against the drain plug when the plunger is in the closed position; characterised in that the plunger is selectively movable axially between a closed position, an open position, and a removal position; the stem has a polygonal head, and a knob is threadably coupled to the plunger having a polygonal bore (B), for engaging the polygonal head of the stem when the plunger is in the removal position and a relief area (A) within which the polygonal head can freely rotate when the plunger is in the open and closed positions; whereby rotation of the knob when the plunger is in the removal position causes the stem to rotate with respect to the drain plug and rotation of the knob when the plunger is in the open and closed positions causes the plunger to rotate freely about the stem. In a preferred embodiment of the drain stopper according to the invention, the movement regulating means comprises resilient friction means disposed within the generally cylindrical bore of the plunger and bearing against the stem. In a particularly preferred embodiment of the drain stopper according to the invention, the resilient friction means comprises an O-ring and the stem further comprises a reduced portion and a channelled portion, the O-ring surrounding the reduced portion when the plunger is in the closed position, and surrounding the channelled portion when the plunger is in the open position. It is preferred that the drain stopper according to the invention further comprises a seat portion within the generally cylindrical bore, and retaining means for retaining the O-ring against the seat portion. It is particularly preferred that the stem of the drain stopper according to the invention further comprises an expanded portion between the reduced and channelled portions, such that when the plunger is moved axially from the closed to the open position, the O-ring is compressed, thereby offering resistance to the axial motion of the plunger, and such that the O-ring snaps into the channelled portion when the plunger reaches the open position. The plunger is preferably composed of unitary thermoplastic material, and the stem is preferably composed substantially of unitary metallic material. The invention will now be further described with reference to the accompanying drawings of a preferred embodiment of a drain stopper according to the invention, in which, Figure 1 shows a perspective view of the drain stopper according to the invention, Figure 2 shows a view partially in cross-section of the drain stopper according to the invention in the open position and, Figure 3 shows a view partially in cross-section of the drain stopper according to the invention in the closed position. The vandal proof drain stopper according to the invention is installed on a drain plug 44 having a threadable outer surface 32, which is threadably engaged with a water outlet source of a bath or other similar vessel. The drain stopper operates within the plug 44 to close or open the drain plug. The drain stopper has a lower threaded stud portion 28 which threadably engages with a bore 30 in the lower region of the drain plug 44. Rising upwardly from the threaded stud portion 28 is a stem 10. In snug contact and circumferentially surrounding the stem 10 is a plunger 46. The stem 10 is fixedly maintained within the drain plug by virtue of the stem's threadable engagement of stud portion 28 with threaded bore 30 of the drain plug. In the preferred embodiment, the plunger 46 and stem 10 are comprised, respectively of thermoplastic material and metal, in particular brass, but it will be appreciated that other similar materials may be used. The stem 10 has a polygonal, preferably hexagonal, head 12 which facilitates tight and secure engagement with threaded bore 30 of the drain plug 44. The knob 34 has a relief A inside the polygonal, preferably hexagonal, bore B so that the knob 34 and plunger 46 assembly rotate freely about the stem so that mere turning of the knob 34 will not unthread the cap 40 from the drain stopper assembly as long as hexagonal head 12 is within relief area A. As such, the stem 10 will not easily become threadably disengaged from the drain plug 44, thereby greatly discouraging removal of the knob and plunger assembly, and preventing vandalism of the drain plug and knob. The plunger 46 goes upwardly and downwardly in a vertical direction guided by the stem 10 in response to manual upward pulling or pushing on knob 34. The knob 34 has a threaded portion 17 which is threadably engaged with a threaded portion 36 of the plunger 46, so that the knob and the plunger work together as an integral unit. Fixedly mounted between the knob 34 and the plunger 46 is a cap 40, which serves as a decorative cover protection of seal 38 which is mounted within circumferential groove 48 of the plunger 46. Upward pulling on the knob 34 brings the seal 38 to its open position, thereby opening the drain while downward pushing on the knob 34 engages the seal 38 into sealing contact with an outer circumferential flange 45 of the drain plug 44, as shown in Figure 2, thereby effectively sealing the drain. The stem 10 has a reduced portion 24, a tapered portion 25, an expanded portion 55 and a channelled portion 16. The significance of this structure will later be described. An O-ring 18 is disposed within the inner diameter of the plunger 46 and is retained against seat 50 by metal washer 22. The washer 22 is in turn retained by knob 34. The O-ring 18 acts as a frictional element. In the closed position of the plunger, the inner circumference of this O-ring rests within the reduced area 24 of the plunger 46, the O-ring being maintained in a snugly seated position between the metal washer 22 and a bottom seat portion 50 of the stem 10, as shown in Figure 3. When the plunger 46 and the seal 38 are in their closed position and a user grips the knob 34 and pulls upwardly thereupon, the plunger 46 moves in concert and brings with it the O-ring 18, which then moves upwardly along reduced portion 24 to tapered portion 25, thereby giving the user a tactile feedback that the plunger is encountering a force opposing the pulling force of the user. As the knob 34 is upwardly pulled the plunger pulls the O-ring, which is resilient, onto an expanded portion 55 of the stem 10, thereby providing a greater resisting force to the user. As the user continues to pull upwardly, the O-ring contracts from its expanded position at expanded portion 55, which position gives greatest opposing force to the pulling force exerted by the user, to a contracted position wherein the O-ring contracts into nesting engagement within the channel 16 of the stem 10. This is accomplished with a tactile "snap in place" feel, such that the user has further tactile feedback that the knob is in its fully open position. In order to remove the drain stopper assembly, the knob must be deliberately pulled beyond its fully open position and turned at the same time so that the hexagonal bore B of the knob 34 will engage with the hexagonal head 12 of the stem 10, and also overcome the resistance of O-ring 18 against stem 10. This motion is not natural but must be done with the knowledge of how the vandal resistant mechanism works. Conversely, when pushing the knob downwardly, a user first encounters greater resistance when the O-ring is forced to expand over expanded portion 55, somewhat less friction as the O-ring is forced over tapered portion 25 and little resistance when the O-ring enters the region of reduced area 24, wherein the O-ring is in a relaxed condition in its closed position, as shown in Figure 3. It will be appreciated that the push-pull drain stopper according to the invention is vandal resistant and offers an effective drain stopper which gives highly satisfactory tactile feedback to the user and employs, essentially, only two moving parts (stopper 46 and O-ring 18) thereby providing an effective drain stopper which is easy to manufacture at a relatively low cost. Further, since the drain stopper according to the invention uses only a few parts and does not rely upon springs or complicated cam-actions, as do the known stoppers, the drain stopper according to the invention can be used for an extended period of time without the need for mechanical maintenance or replacement.

Claims: 1. A vandal resistant push-pull drain stopper for use with a drain plug (44) of a bath or other similar vessel, which drain stopper comprises a plunger (46) having a generally cylindrical bore; a stem (10) threadably coupled (28, 30) to the drain plug and coaxially disposed within the generally cylindrical bore of the plunger (46); movement regulating means (18) for regulating the axial movement of ihe plunger; and sealing means (38) disposed peripherally about the plunger (46) for sealing against the drain plug (44) when the plunger is in the closed position; characterised in that the plunger (46) is selectively movable axially between a closed position, an open position, and a removal position; the stem (10) has a polygonal head (12), and a knob (34) is ihreadably coupled to the plunger (46) having a polygonal bore (B), for engaging the polygonal head (12) of the stem (10) when the plunger (46) is in the removal position and a relief area (A) within which the polygonal head (12) can freely rotate when the plunger (46) is in the open and cloned positions; whereby rotation of the knob (34) when the plunger (46) is in the removal position causes the stem (10) to rotate with respect to the drain plug (44) and rotation of the knob (34) when the plunger (46) is in the open and closed positions causes the plunger to rotate freely about the stem (10). 2. A drain stopper according to claim 1, characterised in that the movement regulating means comprises resilient friction means (18) disposed within the generally cylindrical bore of the plunger and bearing against the stem (10). 3. A drain stopper according to claim 2, characterised in that the resilient friction means (18) comprises an O-ring and the stem (10) further comprises a reduced portion (24) and a channelled portion (16), the O-ring (18) surrounding the reduced portion (24) when the plunger is in the closed position and surrounding the channelled portion (16) when the plunger is in the open position. 4. A drain stopper according to claim 3, characterised in that the plunger (46) further comprises a seat portion (50) within the generally cylindrical bore and the drain stopper further comprises retaining means (22) for retaining the O-ring (18) against the seat portion (50). 5. A drain stopper according to claim 4, characterised in that the stem (10) further comprises an expanded portion (55) between the reduced (24) and channelled portions (16) such that when the plunger (46) is moved axially from the closed position toward the open position the O-ring (18) is compressed, thereby offering resistance to the axial motion of the plunger (46), and such that the O-ring (18) snaps into the channelled (16) portion when the plunger (46) reaches the open position. 6. A drain stopper according to claim 5, characterised in that the plunger (46) is made of unitary thermoplastic material. 7. A drain stopper according to claim 5 or claim 6, characterised in that the stem (10) is substantially made of unitary metallic material. 8. A vandal resistant push-pull drain assembly for use with a bath or other similar vessel having a drain, characterised in that the drain assembly comprises, a drain stopper according to any of claims 1 to 7, and a drain plug (44) insertable in the drain.

Inventors: RIVERA, SAMUEL T.
Applicants: PRICE PFISTER, INC.
Application year: 1989
Main classification: E03C1
IPC codes: E03C1, A47K1