One-size-fits-nearly-all, bendable, plastic lift arm for toilet flushers
A toilet flusher in which the plastic lift arm normally hidden from view inside a toilet tank comprises a bi-concave segment readily bent by hand, allowing the toilet flusher to integrate well with a wide variety of flush mechanisms already found installed inside toilet tanks. Bending forces are concentrated along a line rather than at a point, so that the inadvertent cracking of the lift arm during on-site modification that sometimes occurs in lift arms having cruciform cross sections is much less likely to occur.
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STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENTNot Applicable
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SEQUENCE LISTINGNot Applicable
BACKGROUND OF THE INVENTIONThis invention relates to the plastic lift arms found inside conventional, North American toilet tanks, in particular to an improvement in their stress-strain architecture. These lift arms help to trigger the sudden release of water into a toilet's bowl that occurs when a person actuates the toilet's external flush handle, typically by rotating it counterclockwise. The lift arm rigidly transmits the rotary movement to a slack chain that connects the lift arm to a water valve within the tank, at the tank's juncture with the toilet's porcelain bowl. The lift arm lifts the chain. The chain tenses. An instant later, the chain lifts the water valve, opening it, and flushing starts.
Although lift arms have been generally made out of either metal or plastic, in recent decades the newer plastic arms have captured an ever enlarging share of the refit/repair market. Plastic lift arms first became commonplace only after an injection moldable architecture capable of holding both beaded and link chains was disclosed in U.S. Pat. No. 3,518,703 to Haldopoulos, et at. (1970). All rather similar, lift arms, both metal and plastic, nevertheless show a sufficient variety among them that no single, replacement toilet flusher, that is, a flush handle that a person can actuate together with a permanently attached lift arm, or alternatively together with a removably but securely attached lift arm (such as disclosed in U.S. patent application Ser. No. 10/967,227), can integrate well with all existing installations absent some on-site modification. Idiosyncratic differences among the flush mechanisms that have been sold over the decades by dozens of different manufacturers as original equipment, some dating back into the 1940s and earlier, have militated against a universal fixture.
Clearly, it has been desirable as a marketing matter to offer a plastic lift arm that could be readily adapted to work well in most, if not absolutely all, existing installations. Such one-size-fits-nearly-all lift arms have been available attached to conventional, plastic flush handles for several years, but they have been observed to crack at times when bent during their on-site modification. Not to crack in half, or even to crack so as to render the lift arms useless, but just enough to make an installer, possibly a first-time, do-it-yourself apartment dweller, wonder whether he/she has just compromised or else, worse, just ruined the thing. The experience is not confidence-inspiring. The available plastic lift arms furthermore do not appear to have been designed ergonomically, at least not from the perspective of novice fingers wishing to bend one in order to conform it to an existing lift arm slated for the dumpster. The present invention offers an improvement over these deficiencies.
SURVEY OF BACKGROUND ARTThe applicant knows of only a single U.S. patent that deals directly with the bendability of plastic, toilet-flusher lift arms: U.S. Pat. No. 6,092,245 to Jones (2000). Jones (who uses “lever” or “lever arm” for what is here called a “lift arm”) recommends using ABS, in particular the brand known as Cycolac (misspelled in Jones' patent as Cyclolac) GSM 450, for the lift arm, noting that the lift arm must retain its new form after it is bent (Jones, column 5, lines 4-8). Whether the manufacturers who currently market toilet flushers having bendable plastic lift arms actually use Jones' recommended ABS is not known. What is apparent, however, is that Jones' cruciform architecture for plastic lift arms is both widely employed and is the source of the cracking phenomenon herein addressed.
Many U.S. Patents have been granted on toilet flushers having lift arms that, conceivably, might easily be bent. An example is U.S. Pat. No. 2,529,844 to Keller (1950), with brass lift arm 13 (Keller calls it “lever 13”) having flat, presumably stamped segments along its length, each such segment pierced by a hole 45. Keller's lift arm 13 has a round cross section and thus should bend preferentially and comparatively easily near the midpoint of any of its flattened segments. The reason is that each of Keller's holes 45 discontinuously weakens the flat segment wherein it is centrally located, thus inviting easy bending. Keller himself, however, never addresses bending.
Canadian Design Patent 88158 to Elka Industries, Inc. (1999) shows a lift arm having a perfectly flat (Elka,
In neither Keller, however, nor Jones nor Elka are cross sections shaped to distribute bending forces in an advantageous manner without discontinuities.
BRIEF SUMMARY OF THE INVENTION The present invention rejects the cruciform cross section of Jone's “lever arm shaft 311 at its “bend point” (Jones,
The present invention non-destructively concentrates bending stress by introducing a cylindrically bi-concave segment between the lift arm's pivot portion and the lift arm's free end. The radii of this cylindrical bi-concavity are long relative to the bi-concave segment's thickness, and extend from parallel center lines on opposite sides of the segment's medial plane. The segment's thickness is thus the distance between the center lines minus the sum of the cylindrical radii. The respective sagittae of the curvatures from one end to the other of the bi-concave segment are small relative to the segment's thickness, but are visually evident. Thus, the bi-concave segment is gently but also noticeably curved.
Given such an architecture, even a novice installer can confidently bend the lift arm to match some outgoing lift arm, be the outgoing lift arm made of brass and/or plastic, because there is now a visual cue that locates the point of easiest bending. Clearly the point of easiest bending is in the middle of the bi-concave segment, in a region that also feels slightly cupped (preview
Furthermore, because the new architecture does not have a narrow, arched member just opposite to the point of the application of bending force, that member's arched top is not available to give way and crack as the plastic immediately adjacent to and beneath the arch stretches. Bending forces in the plastic are concentrated at most along a line parallel to the cylindrical axes rather that at a point as bending occurs, so that strain beyond the elastic limit of the plastic is less likely to occur. Thus, the disconcerting unease of observing a crack develop also becomes less likely.
In all, the customer is supplied with a lift arm that is both easier to bend to match an existing installation and that is also less likely to crack in actual fact or, worse, appear to break, than a plastic lift arm made of the same plastic but having the conventional cruciform architecture.
Important objects of the present invention are thus
- 1) To minimize product returns based on perceived or real part failure;
- 2) To reduce real part failure;
- 3) To provide a comfortable-to-modify, ergonomic product for novice installers;
- 4) To stimulate customer satisfaction by providing built-in visual cues to supplement quickly-discarded, printed directions; and
- 5) To stimulate customer satisfaction by providing built-in tactile cues that likewise supplement printed directions.
These and still-further objects and advantages of the present invention will become apparent from a consideration of the following drawing, detailed description, and appended claims.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGReferring to the drawing, wherein like reference characters indicate like parts or elements throughout the several views, and wherein arrowheads indicate physically-composite objects whose numbered resolution into constituent parts occurs only when it is germane to the discussion:
Relative to their respective front tank walls the angles of the lift arms in common use appear to cluster. There is a cluster of small angles, typified by
A close variant of the present invention arises when R1 is as shown in
Inasmuch as modifications and alterations apparent to one skilled in the art may be made to the herein described embodiments of the present invention without departing from the scope and spirit thereof, it is intended that all matter contained herein be interpreted in an illustrative, and not in a limiting, sense with respect to the invention claimed in the following claims and equivalents thereto.
Claims
1. A toilet flusher comprising a flush handle and a lift arm, said toilet flusher being adapted to transmit motion to said lift arm when said toilet flusher is attached to the water tank of a toilet and said flush handle is actuated by a person, said lift arm being made of plastic and comprising a bi-concave segment, and said lift arm being bendable by a force applied to said bi-concave segment.
2. A toilet flusher as in claim 1 wherein said force is applied by hand.
3. A toilet flusher as in claim 1 wherein said bi-concave segment has a least cross section, and wherein any other cross section of said bi-concave segment parallel to said least cross section has an area larger than the area of said least cross section.
4. A toilet flusher as in claim 1 wherein said bi-concave segment has two cylindrical surfaces.
5. A toilet flusher as in claim 4 wherein said two cylindrical surfaces have equal radii of curvature.
6. A toilet flusher as in claim 4 wherein one of the cylindrical surfaces is visually indistinguishable from a flat surface.
7. A toilet flusher as in claim 4 wherein said bi-concave segment has a thickness and said two cylindrical surfaces have parallel axes, and said thickness is equal to the perpendicular distance between said axes minus the sum of the radii of said two cylindrical surfaces.
8. A toilet flusher comprising a flush handle and a lift arm, said toilet flusher being adapted to transmit motion to said lift arm when said toilet flusher is attached to the water tank of a toilet and said flush handle is actuated by a person, said lift arm being made of plastic and comprising a segment adapted for bending, and wherein said segment adapted for bending comprises a visual cue directing the application of a bending force.
9. A toilet flusher as in claim 8 in which said visual cue is a cupped region of said lift arm.
10. A toilet flusher comprising a flush handle and a lift arm, said toilet flusher being adapted to transmit motion to said lift arm when said toilet flusher is attached to the water tank of a toilet and said flush handle is actuated by a person, said lift arm being made of plastic and comprising a segment adapted for bending, and wherein said segment adapted for bending comprises a tactile cue directing the application of a bending force.
11. A toilet flusher as in claim 10 in which said tactile cue is a cupped region of said lift arm.
Type: Application
Filed: May 5, 2006
Publication Date: Nov 8, 2007
Inventor: Michael Olshausen (Washington, DC)
Application Number: 11/418,248
International Classification: E03D 5/00 (20060101);