Patent Publication Number: US-6901610-B1

Title: High performance valve assembly for toilets

Description:
FIELD OF THE INVENTION 
   The present invention is directed to a flush valve assembly for use in a water tank of a toilet. More particularly, the present invention is directed to a flush valve assembly having a coaxial design that provides enhanced energy throughput and thereby optimizes the amount of available energy to effect waste removal from the toilet bowl. The valve assembly of the present invention consistently maximizes energy throughput by employing a large orifice diameter in combination with a trip release mechanism and a secondary float assembly pivotably affixed to a valve body. The flush valve of the present invention also includes shock-absorbing structure for quiet closure of the valve opening and a baffle cup that reduces splashing within the tank. 
   BACKGROUND OF THE INVENTION 
   Toilets for removing waste products are well known. Typically, toilets incorporate three systems that work together to perform the flushing action: the bowl siphon, the flush mechanism and the refill mechanism. Working in concert, these three systems allow the flushing function of the toilet. Usually, the tank, positioned over the back of the bowl, contains water that is used to initiate the siphoning from the bowl to the sewage line, after which fresh water refills the bowl. When a user desires to flush the toilet, the user depresses the flush lever on the outside of the tank, which is connected on the inside of the tank to a movable chain or lever. Upon depression, the flush lever moves a chain or lever on the inside of the tank, thereby lifting and opening the flush valve and to cause water to flow from the tank and into the bowl initiate the toilet flush. 
   In many toilet designs, water flows directly into the bowl and disperses into the rim of the toilet bowl. The water releases into the bowl rather quickly, with flow form the tank into the bowl typically lasting approximately 2 to 4 seconds. The water flows from the rim, down a channel within the sides of the bowl and into the large hole at the bottom of the toilet (commonly known as a siphon jet). The siphon jet releases most of the water into an adjoining siphon tube, thereby initiating the siphon action. The siphoning action draws all of the water and waste out of the bowl and into the siphon tube. The waste and water continues through the other end of the siphon tube through an area known as the trapway and is then released into the wastewater line connected at the base of the toilet. Once the tank is emptied of its contents during the flush, the flush valve closes, and a floating mechanism which has now dropped in the tank to some residual amount initiates the opening of the filler valve. The filler valve provides fresh water to both the tank and the bowl through separate flows. Eventually the tank fills with water to a high enough level to cause the float to rise, thus shutting off the filler valve. At this point, the flushing cycle is complete. 
   The excessive consumption of potable water, however, remains a dilemma for water agencies, commercial building owners, homeowners, residents and sanitaryware manufacturers. An increasing global population has negatively affected the amount and quality of suitable water. In response to this global dilemma, many local and federal authorities have enacted regulations that reduce the water demand required by toilet flushing operations. In the United States, for instance, government agencies that regulate water usage have gradually reduced the threshold for fresh water use in toilets, from 7 gallons/flush (prior to the 1950s) to 5.5 gallons/flush (by the end of the 1960s) to 3.5 gallons/flush (in the 1980s). The National Energy Policy Act of 1995 now mandates that toilets sold in the United States can only use 1.6 gallons/flush (6 liters/flush). Current agency requirements further mandate that the activation means (usually the flush lever or button) for the flush valve assembly sustain a minimum “hold down” time of 1 second without exceeding 1.6 gallons/flush (6 liters/flush). It has been found, however, that the hydraulic performance characteristics of the flush valve are significantly enhanced if water evacuates the tank in a dumping time of less than 1 second, preferably 0.5 to 0.6 seconds. 
   Sanitaryware and flush valve manufacturers have attempted various techniques to comply with reduced water requirements and minimum “hold down” times. Such compliance has proven difficult to combine with enhanced flushing and sanitary performance. In the crowded art of producing a more reliable, more efficient and more powerful 1.6 gallon (6 liter) gravity toilet, one method to more effectively remove waste from the toilet bowl is to increase the hydraulic energy available during the flushing operation. Unfortunately, conventional flush valve configurations employ a coaxial flush valve assembly wherein the effective flow diameter through the flush valve opening is less than the orifice diameter of the flush valve inlet under dynamic conditions. Such configurations therefore do not utilize the maximum available hydraulic energy. 
   The inventor has overcome such detriments in toilet technology in co-pending application U.S. Ser. No. 10/232,878, filed Aug. 30, 2002 and entitled HIGH PERFORMANCE FLUSH VALVE ASSEMBLY (the entire disclosure of which is hereby incorporated by reference). This application discloses a flush valve assembly for a water tank of a toilet that includes a valve body secured thereto. The valve body has a base sleeve portion including a radiused inlet to increase the discharge coefficient of the valve opening. A flush cover member is coaxially and slidably mounted with respect to the valve body so that the valve opening is created therebetween when the flush cover member is removed form the valve body via reciprocating motion. The flush cover member is slidably movable between a first position, wherein the flush cover member is seated on the base sleeve portion of the valve body and thereby obstructs water flow through the valve opening, and a second position, wherein the second valve member is removed from the base sleeve portion of the valve body to permit water flow through the valve opening. A sealing member is provided to ensure a proper seal when the flush cover member is in the first position, and a guiding means is provided that properly aligns and guides the flush valve cover relative to the valve body. The flush valve assembly also includes a trip release mechanism that releases the effects of the flush lever on the flush cover member when the flush cover member reaches its second position, thereby returning the flush cover member to its first rest position prior to the flush lever returning to its own corresponding rest position. In this configuration, the disclosed flush valve assembly ensures compliance with the mandated water requirements and simultaneously provides enhanced cleanliness and waste removal capabilities. The flush valve assembly achieves these functions and also releases the effect of the flush lever so that the valve opening can close before the expiration of the mandated minimum “hold down” time (1 second without exceeding the total water per flush mandate of 1.6 gallons (6 liters)). 
   It is desirable to provide the aforementioned benefits in a flush valve assembly having additional flushing features. In particular, it is desirable to provide a flush valve assembly with enhanced noise dampening qualities and minimal splash back of water in the toilet tank. Such features should be incorporated in the flush valve assembly without compromising the water conservation benefits and hold down time of the prior disclosed flush valve assembly. 
   SUMMARY OF THE INVENTION 
   It is an advantage of the present invention to provide a flush valve assembly that overcomes the deficiencies of conventional flush valve assemblies. 
   It is also an advantage of the present invention to provide a flush valve assembly having optimal energy throughout of the flush water in comparison to existing flush valve assemblies to thereby provide more available energy for waste removal from the toilet bowl. 
   It is a further advantage of the present invention to provide a flush valve assembly that satisfies governmental agency requirements for a minimum “hold down” duration. 
   It is yet a further advantage of the present invention to provide a flush valve assembly that includes a “trip-release” mechanism to release the effect of the flush activation member (i.e., flush lever) upon closure of the valve opening so that a predetermined quantity of flush water is quickly delivered into the toilet bowl without exceeding mandated agency requirements. 
   It is still a further advantage of the present invention to provide a flush valve assembly having all of the aforementioned benefits in combination with noise reduction capabilities. 
   It is still another advantage of the present invention to provide a flush valve assembly having all of the aforementioned benefits in combination with reduced splashback of fluid in the toilet tank. 
   In accordance with these and other advantages, the present invention provides a flush valve assembly for a water tank of a toilet. The flush valve assembly of the present invention includes a valve body having a base portion that is secured to the water tank and a first cylindrical tube member that extends longitudinally upward from the base portion along a longitudinal axis of the valve body. The first cylindrical tube member is concentrically defined relative to an annular support that supports an annular insert thereon and an annular base adjacent the base portion. A flush cover member having a predetermined length is coaxially and slidably mounted with respect to the valve body so as to create a valve opening therebetween when the flush cover member is removed from the valve body. The flush cover member is slidably movable between a first rest position, wherein the flush cover member is seated on an inner peripheral flange member of the base portion of the valve body to obstruct fluid flow through the valve opening, and a second position, wherein the flush cover member is removed from the inner peripheral flange member to allow water to pass through the valve opening. A guiding means is provided for properly guiding and aligning the flush cover member with respect to the valve body when the flush cover member is moved between the first and second positions. This guiding means includes a second cylindrical tube member secured to the flush cover member and slidably fitted over the first cylindrical tube member so that the flush cover member is properly guided and accurately aligned with the valve body when the flush cover member is moved between its first and second positions. The guiding means further includes at least one alignment tab on the flush cover member that remains in sliding engagement with at least one corresponding tab recesses defined in the valve body so as to enable longitudinal and central alignment of the flush cover member relative to the valve body. 
   The flush valve assembly of the present invention may also include a secondary float assembly pivotably affixed to the valve body. The secondary float assembly includes a flotation cup having a wall defining the periphery thereof and a flotation cavity therewithin, and a resilient member integral with the flotation cup. The resilient member engages one of a plurality of ratcheted teeth provided on a cantilever portion of a pawl member in communication with the flotation cup. A recess is defined along a length of the wall adjacent the pawl member so as to receive a flange portion thereof and effect securement of the flotation cup and the pawl member to one another. The pawl member further includes retention members in combination with each of a primary finger and a secondary finger that engage the flush cover member during reciprocating movement thereof. More specifically, an integral tab portion along an outside peripheral surface of the flush cover member engages at least one of the primary finger and secondary finger when the flush cover member moves between its first rest position and its second position. The secondary float assembly communicates with the valve body and flush cover member via engagement of the secondary float assembly with a portion of the valve body. 
   The flush valve assembly of the present invention cooperates with a flush lever displaceable by a user between a first rest position and a second position to operatively move the flush cover member between its first rest position and its second position, respectively. The flush valve assembly may further include trip release means for releasing the effect of the flush lever on the flush cover member when the flush cover member reaches its second position. The trip release means is a trip release mechanism coaxially mounted with respect to the valve body and flush cover member. The trip release mechanism includes a cam rod; a pull rod operatively connected to the flush lever and slidably mounted with respect to the cam rod so that the pull rod and cam rod are movable in response to movement of the flush lever; and a trip dog assembly including means for engaging the flush cover member when the pull rod and cam rod are moved between a first rest position and a second predetermined position, and means for disengaging the flush cover member when the pull rod moves beyond its second predetermined position. The cam rod is mounted within the first cylindrical tube of the valve body, which includes an inwardly extending annular flange member to restrict movement of the cam rod past its second predetermined position. A baffle cup is provided that has an outer periphery defining a float cavity therewithin and having at least one aperture provided therethrough to establish communication among the flush lever, baffle cup and trip release means. 
   Various other advantages and features of the present invention will become readily apparent from the ensuing detailed description and the novel feature will be particularly pointed out in the appended claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a schematic of a toilet assembly having a tank within which a flush valve assembly of the present invention is utilized. 
       FIG. 2  shows a perspective view of a high-performance flush valve assembly of the present invention. 
       FIG. 2(A)  shows the flush cover member of the flush valve assembly of  FIG. 1  apart from the valve body thereof. 
       FIG. 3  shows an exploded view of the flush valve assembly of  FIGS. 2 and 2(A) . 
       FIGS. 4 ,  5 ,  6  and  7  show a cross-sectional view of the flush valve assembly of the present invention, including the baffle cup and secondary float assembly thereof, while the flush valve assembly is in a closed position, during opening, in a fully opened position and during closing, respectively. 
       FIGS. 8 ,  9 ,  10  and  11  show cross-sectional views of the flush valve assembly of the present invention, including the trip release mechanism thereof, corresponding to the valve positions shown in  FIGS. 4 to 7 . 
       FIG. 12  shows a perspective view of a pull rod used in a trip release mechanism of the present invention. 
       FIG. 13  shows a perspective view of a wing-like retention member used in cooperation with the pull rod of  FIG. 12  in a trip release mechanism of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   A flush valve assembly  10  in accordance with the teachings of the present invention is illustrated in  FIG. 1  incorporated in a toilet assembly  2 . As will be explained in more detail below, flush valve assembly  10 , which is provided in a water tank  4 , has a greater energy throughput of flush water in comparison to existing flush valves assemblies to thereby utilize maximum available energy to remove waste from toilet bowl  5 . In addition, the present invention enables a toilet to meet regulatory mandates that require a minimum hold down time of 1 second and a maximum water usage of 1.6 gallons (6 liters) per flush. Flush valve assembly  10  allows water tank  4  to hold a predetermined volume of water and also supply a conduit to deliver reseal water to the toilet trapway via the passages within the toilet (this delivery is well known within the art). As illustrated in  FIGS. 2 to 11 , flush valve assembly  10  of the present invention includes valve body  12 , flush cover member  14  of a predetermined length and a trip-release mechanism  16  (as described further hereinbelow). 
   Valve body  12  includes base portion  18  that is secured to water tank  4  by one or more fasteners inserted through corresponding apertures  18   a  provided along an outer peripheral extent  18   b  of base portion  18 . Valve body  12  also includes a first cylindrical tube member  20  that extends longitudinally upward from base portion  18  along a longitudinal axis of valve member  12 . Cylindrical tube member  20  is concentrically defined relative to annular support  12   a  of valve member  12  that supports annular insert  22  thereon (described further herenbelow) and annular base  12   b  adjacent base portion  18 . A plurality of support members  24  extending between annular support  12   a  and annular base  12   b  are distributed generally circumferentially relative thereto. A sealing member  26  is provided adjacent valve body  12  so as to abut against an annular flange surface  18   c  of base portion  18  and thereby seals flush valve assembly  10  to the water tank. 
   Base portion  18  of valve body  12  includes a radiused inlet  38  having has an approximate diameter of 4.5″ with a radius b of 1″ (see  FIG. 4 ) incorporated onto the leading edge  38   a  of the inlet. As a result, radiused inlet  38   a  of base portion  18  creates a discharge coefficient of the valve opening of approximately 0.95. The discharge coefficient is the ratio between the actual flow area of the opening area and the static opening area. In practice, the higher the discharge coefficient of the opening, the greater the hydraulic energy of the water passing through the opening. Without providing a radiused inlet at the valve opening with a lead-in angle as in the present invention, the discharge coefficient of the typical prior valve opening is approximately 0.6. Accordingly, the throughput energy of the flush water passing through valve opening  30  of flush valve assembly  10  substantially exceeds the throughput energy of the flush water passing through existing valve assemblies of the prior art, thereby generating more available energy for waste removal. 
   Flush cover member  14  is an enclosure component that is coaxially and slidably mounted with respect to valve body  12  so as to create a valve opening  30  therebetween when the flush cover member is removed from the valve body. Flush cover member  14  is slidably movable between a first rest position, wherein the flush cover member is seated on an inner peripheral flange member  32  of base portion  18  of valve body  12  so that water cannot pass through the valve opening (see  FIGS. 2 ,  4 ,  7 ,  8  and  11 ), and a second position, wherein the flush cover member is removed from the inner peripheral flange member to allow water to pass through the valve opening (see  FIGS. 5 ,  6 ,  9  and  10 ). The second position comprises the end of the flush cycle, and thereby assumption of the second position determines the duration of the flush. 
   When in the closed position, valve opening  30  is obstructed, thereby preventing the passage of flush water therethrough until actuation of flush valve assembly  10  by a flush activation member such as displaceable flush lever  7  (shown in  FIG. 1  in communication with flush valve assembly  10  via activation chain  11 ). In the open position, valve opening  30  allows flush water to flow therethrough and proceed into passages within the toilet to which the water tank is attached (as is known in the art). In order to accommodate unrestricted overflow in water tank  4 , flush cover member  14  includes a funneled inlet  39  at flush water inlet orifice  40 . Funneled inlet  39  has a predetermined lead-in angle β relative to the horizontal axis of flush cover member  14  (see  FIG. 4 ). 
   As in conventional flush valve assemblies, flush cover member  14  initially moves from its first rest position, wherein valve opening  30  is closed, to a second position, wherein valve opening  30  is opened by means of flush lever  7 . Flush lever  7  is displaceable by a user between a first rest position and a second open position corresponding to movement of flush cover member  14  between its first and second positions, respectively. Flush cover member  14  is desirably a non-buoyant member. 
   In order to reduce hydraulic losses and further improve the flow characteristics of flush valve assembly  10 , valve body  12  includes means to minimize flow resistance. This flow resistance minimization means desirably includes a plurality of tapered web members  58  radially disposed between first cylindrical tube member  20  and an inner peripheral portion  60  of base portion  18  of valve body  12 . This configuration minimizes the turbulence of the flush water passing through valve opening  30 . 
   As shown in the figures and particularly shown in  FIG. 2(A) , flush cover member  14  includes an upper portion  14 ′, a lower portion  14 ″ and an intermediate portion  14 ′″ therebetween which may be a stepped or inclined portion. The diameter of upper portion  14 ′ may be smaller than that of lower portion  14 ″. Additionally, annular sealing member  44  provided along the bottom surface of flush cover member  14  has a diameter that may exceed the diameter of lower portion  14 ″. As particularly shown in  FIG. 4 , inner peripheral flange member  32  is disposed outside an outer circumferential surface of flush cover member  14 , and lip  44   a  of flush cover member  14  rests thereon when the flush cover member is in its first rest position. O-ring  45  may be placed in communication with annular sealing member  44  to provide further sealing cooperation among flush cove member  14 , valve body  12  and tank  7  within which flush valve assembly  10  is disposed. When the flush cover member  14  is in its second (floated) position so that flush valve opening  30  is unobstructed (see  FIG. 5 ), water backflow tends to migrate (rise) in the interior space of flush cover member  14 . In order to restrict further upward migration of the backflow, an annularly inclined baffle member  80  extends from an inner peripheral surface of flush cover member  14 . 
   Intermediate portion  14 ′″ and the diameter of annular sealing member  44  may be designed and/or selected so as to enable a force to be exerted on flush cover member  14  during a filling operation that is sufficient to pull flush cover member  14  down and cause a proper seal to be formed. Such force may be the minimum force necessary to pull flush cover member  14  down and provide the proper seal. The flow characteristics of the flush water and the flow capacity of flush valve assembly  10  are enhanced by reducing the pulling force necessary to close and properly seal the valve opening  30  when flush cover member  14  is moved from its second upper position to its first rest position. In accordance therewith, inner peripheral flange member  32  is provided downstream of radiused inlet  38  in valve opening  30 . 
   In order to properly guide and align flush cover member  14  with respect to valve body  12  when flush cover member  14  is moved between its first rest position and its second position, flush cover member  14  includes a second inner cylindrical tube member  48  secured to the inner peripheral surface of an inner downwardly depending vertical wall member  50 . Securement is desirably effected by a plurality of radially disposed web members (not shown) bridging second tube member  48  between inner wall member  50  and second cylindrical tube member  48 . Second cylindrical tube member  48  is fitted over first cylindrical tube member  20  of valve body  12  so that flush cover member  14  is properly guided and accurately aligned with valve body  12  when flush cover member  14  is moved between its first rest position and its second position. This guiding assembly, comprising first and second cylindrical tube members  20  and  48 , respectively, also assists in properly sealing valve opening  30  when flush cover member  14  returns to its first rest position. The guiding assembly assures that annular sealing member  44  is properly seated on inner peripheral flange member  32  when flush cover member  14  is in its first rest position. 
   Flush valve assembly  10  also includes a secondary float assembly  64  pivotably affixed to valve body  12 . Float assembly  64  includes flotation cup  66  having a wall  66   a  defining the periphery thereof and a flotation cavity  68  therewithin. A resilient member  70  integral with flotation cup  66  engages one of a plurality of ratcheted teeth  72  provided on a cantilever portion  74  of pawl member  76 . A recess  78  defined along a length of wall  66   a  adjacent pawl member  76  receives flange portion  80  thereof to effect securement of flotation cup  66  and pawl member  76  to one another (see  FIG. 3 ). Flange portion  80  extends at least a portion of the length of cantilever portion  74  and includes lateral flange members extending along a plane from which ratcheted teeth  72  depend. Pawl member  76  further includes retention members  82  that receive a fastening element such as retention peg  84  shown in the drawings. Retention members  82  are provided in combination with primary finger  76   a  and secondary finger  76   b  that engage flush cover member  14  during reciprocating movement thereof, and more particularly engage integral tab portion  85  of flush cover member as flush cover member  14  moves relative to valve body  12 . Secondary float assembly  64  communicates with valve body  12  and flush cover member  14  via engagement of the secondary float assembly with recess  86  of annular insert  22 . 
   To further ensure reciprocating guidance of flush cover member  14  relative to valve body  12 , flush cover member includes one or more alignment tabs  52  that remain in sliding engagement with corresponding tab recesses  54  provided in annular insert  22  (see  FIG. 3 ). Alignment tabs  52  prevent rotation of flush cover member  14  and thereby ensure alignment of integral tab portion  85  with primary finger  76   a . Upon assembly of annular insert  22  with valve body  12 , alignment tabs  52  also enable longitudinal and central alignment of flush cover member  14  relative to valve body  12 . Flush cover member  14  further includes one or more damper tabs  56  integrated along an outer circumferential periphery of lower portion  14 ″. Upon closure of valve opening  30 , alignment tabs  52  and damper tabs  56  together ensure alignment and guidance of flush cover member  14  relative to valve body  12  and significantly reduce the noise inherently associated with the valve closing action. During movement, flush cover member  14  remains properly positioned relative to valve body  12  so that passage of flow water through valve opening  30  remains reliable and predictable. This improvement preserves the water conservation and performance benefits of the flush valve assembly and significantly enhances the valve&#39;s noise attenuation properties. 
   Referring more specifically to  FIGS. 4 to 7 , elevation of flush cover member  14  relative to valve body  12  in the direction of arrow A (see  FIG. 5 ) causes tab member  85  of flush cover member  14  to engage primary finger  76   a  and further causes annular sealing member  44  to engage secondary finger  76   b . Such engagement of the primary and second fingers articulates secondary float assembly  64  in the direction of arrow B (see  FIG. 5 ) and retains float assembly  64  in this articulated position during entrance of water in the direction of arrows W (see  FIGS. 5 and 6 ) through valve opening  30  and into tank  4 . At the end of a flush cycle, flush cover member  14  returns in the direction of arrow A′ to its seated position on inner peripheral flange member  32  of valve body  12  (see  FIG. 7 ). The inter-action of this secondary float assembly  64  with the cylindrical closure component provides reliable valve closure with minimal variance in delivered flush water volume. This is a desirable feature that is particularly beneficial for applications with shallow reservoirs (i.e., one-piece toilets). By incorporating a secondary float assembly, flush valve assembly  10  achieves substantial improvements in the consistency of delivered flush volume without compromising flush performance. 
   Current regulatory mandates require that the minimum “hold down” time for the flush lever equal or exceed 1 second. It has been found, however, that the longer the valve opening remains open before evacuation of water from the tank, the more energy is dissipated during the flush cycle. Flush valve assembly  10  of the present invention achieves closure of valve opening  30  in less than 1 second, and preferably in 0.5 to 0.6 seconds, to increase the available hydraulic energy of the flush water and thereby ensure a relatively rapid delivery of a predetermined quantity of flush water without exceeding regulatory mandates. 
   In accordance therewith, flush valve assembly  10  includes trip release mechanism,  16  that, as described hereinbelow, releases the effect of flush lever  7  on flush cover member  14  when flush cover member  14  reaches its second position, thereby returning flush cover member  14  to its first rest position prior to the flush lever returning to its corresponding rest position. Trip release mechanism  14  includes a cam rod  90 , a pull rod  92  operatively connected to flush lever  7  at end  92   a  and slidably mounted with respect to cam rod  90  so that pull rod  92  and cam rod  90  are moveable in response to movement of the flush lever. Pull rod  92  includes a plurality of extension members  94 , each including a narrow width section  94   a  gradually increasing in width to a raised width section  94   b  (see  FIG. 12 ). Raised width members  94   b  extend outwardly to an extent such that they are accepted readily within receiving opening  80   a  formed by an inner peripheral surface of annularly inclined baffle  80 . Each of raised width members  94   b  includes an engaging hole  96  at a lower end thereof. 
   Trip release mechanism  16  incorporates a trip dog assembly  100  that engages flush cover member  14  when pull rod  92  and cam rod  90  are moved between a first predetermined rest position and a second predetermined position. Trip dog assembly  100  disengages flush cover member  14  when pull rod  92  moves beyond its second predetermined position. The engaging and disengaging members of trip dog assembly  100  include wing-like retention members  100   a  that engage cam rod  90  in combination with integral fastening members  100   b  that are supported in engaging holes  96  of raised width members  94   b  (see  FIG. 13 ). Each wing-like retention member  100   a  further includes an engagement section  104  that extends outwardly and is thereby repositioned upon pivoting of the wing-like retention member when cam rod  90  and pull rod  92  return to their first rest positions. 
   As particularly shown in  FIG. 10 , wing-like retention members  100   a  extend outwardly to engage flush cover member  14  when cam rod  60  and pull rod  62  move together in the direction of arrow A (see  FIG. 9 ) between their first and second predetermined positions, correspondingly moving flush cover member  14  between its first rest and second positions. Further movement of cam rod  90  is restricted past this second predetermined position as will be described in further detail below. With the movement of cam rod  90  restricted, wing-like retention members  100   a  retract when pull rod  92  is moved past it second predetermined position so as to disengage wing-like retention members  100   a  from flush cover member  14 , thereby allowing flush cover member  14  to return to its first rest position (see  FIG. 11 ). 
   More specifically, as shown in  FIG. 8 , in the first rest position of cam rod  90  and pull rod  92 , a first catch member  106  of each wing-like retention member  100   a  abuts against a leading inclined surface  108  of a central depression cam section  90   a  of cam rod  90 . A leading edge  108  of a second catch member  110  of each wing-like retention member  100   a  abuts against the reduced diameter section  109  of central depression cam section  90   a  of cam rod  90 . Thus, as flush lever  7  initially moves cam rod  90  and pull rod  92  from their initial rest positions, first and second catch members  106  and  110  are retained adjacent central depression cam section  90   a  of cam rod  90 . Upon further combined movement of cam rod  90  and pull rod  92  due to further depression of flush lever  7 , each retention member  100   a  engages annularly inclined baffle member  80  (see  FIG. 10 ) that extends from an inner peripheral surface of flush cover member  14 , consequently raising flush cover member  14  from its first rest position to its second upper position (wherein valve opening  30  is unobstructed). When cam rod  90  and pull rod  92  have moved to the second predetermined position upon depression of flush lever  7 , annular base flange  112  provided on base section  90   b  of cam rod  90  abuts against inwardly extending flange  114  provided at top end  20   a  of first cylindrical tube member  20  of valve body  12  (see  FIG. 11 ). This configuration restricts further movement of cam rod  90  with pull rod  92  as flush lever  7  is further depressed. 
   When pull rod  92  is moved past its second predetermined position by further depression of the flush lever, pull rod  92  is subjected to additional bias force being applied by a spring member  116  that is fitted over an upper portion of cam rod  90  and loaded between a central core member  118  of the pull rod  92  (see  FIG. 9 ) and a spring knob  120  provided at an upper end of cam rod  90 . Spring member  116  ensures that each retention member  100   a  returns to its rest position upon completion of each flush cycle. Since cam rod  90  is restricted from further movement, when pull rod  92  is moved past the second predetermined position and the biased force is initially applied thereto, first and second catch members  106  and  110  ride out of central depression cam section  90   a  of cam rod  90 . This, in turn, causes wing-like retention members  100   a  to pivot such that engagement sections  104  of the retention members are retracted toward pull rod  92  and disengaged from annularly inclined baffle member  80  of flush cover member  14 . Consequently, since flush lever  7  is connected to pull rod  92 , flush cover member  14  is no longer under the effect of the flush lever. Once the flush cover member is unrestrained, flush cover member  14  is capable of returning to its first rest position. Pull rod  92  continues its upward movement past the second predetermined position until central core member  118  abuts against spring knob  120 . At this point, further movement of pull rod  92  is restricted. 
   The disclosed flushing operation closes the valve opening in approximately 0.5 to 0.6 seconds, providing a relatively quick flush operation and significantly reducing energy dissipation of the flush water during the flushing operation. Even though flush cover member  14  returns to its first rest position to close valve opening  30 , pull rod  92  continues to move upwardly until the flush lever has complied with its mandatory 1 second “hold down” time. 
   In addition, the second cylindrical tube member  48  of flush cover member  14  includes an annular extended flange  122  at an upper end thereof. When cam rod  90  and pull rod  92  return to their first rest position in a subsequent flushing operation and the effect of the flush lever is released, camming surfaces on retracted retention members  100   a  abut annular extended flange  122  and ride thereover. Wing-like retention members  100   a  are thereby cammed to an extended engageable position so that first catch member  106  of each wing-like retention member  100   a  abuts against the leading inclined surface  108  of central depression cam section  90   a . The wing-like retention members are pivoted into a position whereby the engaging member is capable of engaging annularly inclined baffle member  80  of flush cover member  14  in a subsequent flush operation. 
   During the engagement and disengagement of flush valve cover  14  as described hereinbove, articulation of flush lever  7  communicates movement to flush cover member  14  via activation chain  11 , which specifically communicates with pull rod  92  at end  92   a  thereof (see  FIGS. 8 to 11 ). Upon movement of chain  11  and corresponding movement of pull rod  92 , baffle cup  130  also moves accordingly in the direction of arrow A (see  FIG. 10 ). Baffle cup  130  includes aperture  132  along an upper periphery  130   a  thereof to permit ingress of chain  11  therethrough. A free end of chain  11  is captured in upper end  92   a  of pull rod  92 , thereby retaining baffle cup  130  centrally relative to a longitudinal extent of pull rod  92  and cam rod  90 . Baffle cup  130  is a generally cylindrical element having a float cavity  134  defined therewithin. Baffle cup  130  follows the path of pull rod  92  during the flushing operation and descends along with pull rod  92  after closure of valve opening  30 . Incorporation of baffle cup  130  substantially attenuates splashback of water through tank  4  and any undesirable noise associated therewith upon refilling of tank  4 . By significantly reducing splashing within tank  4 , baffle cup  130  desirably reduces atomization of chlorinated water and thereby prevents rapid corrosion of valve and tank components. 
   Various changes to the foregoing described and shown structures are now evident to those skilled in the art. The matter set forth in the foregoing description and accompanying drawings is therefore offered by way of illustration only and not as a limitation. Accordingly, the particularly disclosed scope of the invention is set forth in the following claims.