Liquid dispenser

A liquid dispenser, adapted to rest upon the bottom of a flush tank, includes a container having a quantity of the concentrated soluble material therein, and a closure forming a piston extending into the top opening of the container. The closure forms a liquid flow passage between the interior and exterior of the container and is adapted for shifting in response to the flush/fill modes of the tank cycle. The closure rises to its upper limit by flotation from entrapped air within the closure, retains liquid in an open cavity thereof and becomes fully submerged by the rising level of the tank liquid. As the closure rises, tank liquid enters the container through the flow passage for mixing with the chemical concentrate. During the flush mode of the tank, the closure falls by gravity and is augmented by the retained water in its cavity as the receding level of the tank liquid passes below the upper rim of the closure. As the closure falls it effects a positively controlled piston-displacement discharge of liquid chemical concentrate from the interior of the container into the outflowing tank liquid only at the end of the flush cycle. The piston is formed by a bottom wall of an inner depending wall of the closure, or by an air cushion defined by such inner wall, so as to effect a piston-displacement discharge of the chemical concentrate from the interior to the exterior of the container at the end of the flush cycle. The length of the displacement stroke may be varied to adjust the concentration of the treatment by varying the amount dispensed during each cycle. And, an upper reservoir may be formed on the closure in communication through discharge ports with the flow passage for purging the passage of liquid concentrate during the flush cycle.

BACKGROUND OF THE INVENTION 
This invention relates generally to a liquid dispenser, and more 
particularly to a device for discharging a chemical concentrate from the 
interior of a container into the flush tank of a toilet only at the end of 
the tank flush cycle. 
Prior art chemical dispensers for flush tanks are known for dispensing a 
cleaning fluid into the flush tank of a toilet by employing a positive 
pumping or piston action. Such dispensers have different modes of 
operation and often require the chemical container to be inverted in the 
tank so that the container neck, or a member affixed thereto, functions as 
a stationary piston coacting with a dispensing member or float. Dispensing 
may occur near the end of the flush cycle, or may be responsive to rising 
water levels in the tank. Some of the inverted container-type dispensers 
employ no positive pumping action, and most of such devices are relatively 
complex in their arrangement and operation and are somewhat deficient in 
that they inaccurately meter the chemical into the flush tank. 
A flush tank dispenser having its container positioned upright in the tank 
and employing a positive pumping action for dispensing the product is 
disclosed in U.S. Pat. No. 3,341,074 to Pannutti. However, the length of 
the stroke required during the displacement action allows for undue 
migration of the chemical into the flush tank thereby resulting in an 
overtreating of the tank water and a needless waste of the chemical. 
Besides, more tank water than necessary is permitted to enter the 
container during the tank refill mode before the chemical is sealed off 
from the exterior of the container. And, tank liquid during the tank 
refill mode must enter the container which is open in the same direction 
as the rising water level so that measures must be taken to ensure an 
adequate refilling of the container with tank liquid before it is sealed 
off. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a liquid dispenser, for 
the flush tank of a toilet, which is simple and economical in its 
construction, efficient in its operation, easy to manufacture and makes 
use of a one-piece closure for effectively discharging a chemical 
concentrate in varying amounts, when desired. 
Another object is to provide such a dispenser which permits only a limited 
amount of tank liquid to be admitted to the interior of the container 
after which a flow passage is closed so as to prevent migration of the 
chemical from the container into the tank during the dwell time between 
flushes to thereby avoid a needless wasting of the chemical by 
overtreating the tank liquid. 
A further object of this invention is to provide such a dispenser which 
features a positively controlled piston-displacement discharge of chemical 
concentrate from the interior of a container into the outflowing tank 
water only at the end of the flush cycle, thereby providing a greater 
concentration of chemical in the toilet bowl as the result of this delay. 
A still further object of the present invention is to provide such a 
dispenser comprising an open container having a quantity of concentrated 
soluble material therein capable of being dispensed as a liquid 
concentrate upon the downward stroke of a piston extending into the 
container and being responsive to the falling level of liquid in the tank. 
The piston is part of a closure having an annular wall surrounding the 
container and forming, together with the piston, a flow passage for the 
liquid between the interior and exterior of the tank. The length of the 
piston stroke is controlled by the provision of cooperating stops on the 
container and the closure, and the piston has an upwardly open cavity for 
retaining a quantity of tank liquid when the receding level of the tank 
liquid passes below the upper rim of the closure. Entrapped air in the 
flow passage is retained within the closure during the tank refill cycle 
causing the closure to be buoyed upwardly to its limit stop during the 
tank refill cycle. And, the length of the piston stroke may be varied by 
the use of limit stops spaced at different intervals along the container 
for selective cooperation with a limit stop on the closure upon relative 
rotation. Alternatively, an air cushion provided in lieu of the piston 
effectively functions as a piston in forcing the chemical concentrate 
outwardly of the container. 
A still further object of this invention is to provide such a dispenser as 
having openings between an upper portion of the cavity and the flow 
passage for purging liquid chemical concentrate therefrom during the flush 
cycle. 
Other objects, advantages and novel features of the invention will become 
more apparent from the following detailed description of the invention 
when taken in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION 
Turning now to the drawings wherein like reference characters refer to like 
and corresponding parts throughout the several views, a toilet chemical 
dispenser according to one embodiment of the invention is generally 
designated 10 in FIG. 1 and comprises a container 11 which may be of 
generally circular cross-section having a top opening and being formed of 
a material of a specific gravity sufficiently greater than 1.0 to ensure 
that the container remains positioned on bottom B of a flush tank (not 
otherwise shown) during the flush/fill cycle of the tank until a quantity 
of solid chemical material 12 located within the container is completely 
dissolved and the chemical concentrate is depleted to essential 
exhaustion. Chemical 12 may be in the form of a solid cake for 
disinfecting, deodorizing and cleaning the associated toilet bowl (not 
shown) as the cake dissolves into the liquid with which it is in contact 
until the volume in a space 13, above the solid chemical and beneath the 
piston, is sufficiently concentrated that a saturated solution exists 
within the dispenser. 
The dispenser further comprises a one-piece dispenser closure 14 which is 
actuated by the action of the rising and falling of the water in the flush 
tank which is being treated. The closure may be of a non-metallic 
material, such as a plastic, and comprises a piston 15 defined by an 
annular wall 16 closed at its bottom by a wall 17. The piston itself thus 
forms an upwardly open cavity 18 for the retention of tank liquid when the 
level thereof moves below the top of the closure during the tank flushing 
cycle, as will be more fully discussed hereinafter. 
The container is formed with an annular bead 19 near an upper edge 21 
thereof, the bead extending inwardly of the container and being formed by 
an upsetting of the container wall or in any other suitable manner. An 
outwardly extending annular lip 22 is provided on the piston for 
engagement with bead 19 so as to limit the upward stroke of the piston as 
shown to the right of centerline 23 in FIG. 1. Lip 22 is interrupted along 
its length by a plurality of spaced radially extending slits 24. 
Therefore, engagement between lip 22 and bead 19 does not form a liquid 
seal between the interior and exterior of the container. 
The closure further has an annular depending wall 25 surrounding the 
container, walls 16 and 25 being interconnected by a top annular wall 26. 
And, walls 16 and 25 are respectively spaced from the interior and 
exterior of the container so as to define a liquid flow passage 27 between 
opposite sides of the container. Furthermore, stops such as radially 
extending and circumferentially spaced ribs 28 or the like extend between 
walls 16 and 25. These ribs also form baffles defining cells or pockets 
therebetween for retaining trapped air in the closure whenever submerged, 
including movement in either direction. And, ribs 28 overlie upper edge 21 
of the container so as to bear thereagainst to limit the downward movement 
of the closure relative to the container as shown to the left of 
centerline 23 in FIGS. 1 and 2. Long and slender portions 28a of these 
ribs extend along wall 25 and are slightly spaced from container 11 so as 
to define guide ribs for the closure which will permit a greater annular 
liquid flow passage but nevertheless maintain axial stability of the 
closure against cocking during movement between its upper and lower 
limits. And, in lieu of ribs 28, lugs or a shoulder at the base of the 
container, underlying the lower edge of wall 25, could be provided for 
functioning in a like manner. 
In operation, when dispenser 10 is placed in a toilet flush tank so as to 
rest on bottom B thereof, a quantity of tank liquid L fills cavity 18 and 
likewise enters (depicted by the arrows shown to the right in FIG. 1) the 
interior of the container through passageway 27 so as to fill space 13. As 
the liquid level in the tank rises above the lower edge of wall 25, air 
becomes entrapped beneath the closure to thereby produce a flotation 
effect rendering closure 14 buoyant. The air volume within the dispenser 
is compressed within the pockets (formed by ribs 28) by the rising liquid 
level in the tank to the extent of the head of liquid above the dispenser. 
Closure 14 therefore rises to its upper limit as shown to the right in 
FIG. 1. During the tank flush cycle, the liquid level falls and, when it 
exposes the top portion of the dispenser, the reduced buoyancy of the 
entrapped air in the pockets coupled with the added weight of the liquid 
held in the piston cavity, causes the dispenser to be depressed 
downwardly. The piston thus enters the container displacing the liquid 
chemical concentrate thereunder, and causing it to overflow edge 21 of the 
container through passageway 27 and into the tank liquid. The downward 
movement of the closure is limited by the lower edges of ribs 28 which, as 
mentioned above, retain spaces thereby serving as entrapped air pockets to 
assist in the closure rising movement. Since the chemical concentrate is 
expelled near the end of the flush mode, the concentrate is largely 
retained in the toilet bowl after the flush. 
During the tank refilling cycle, the tank liquid level rises and enters 
passageway 27 so as to flow, in the direction of the arrows shown to the 
right in FIG. 1, into space 13 within the container since the passageway 
is fully open as the liquid rises to the level of top wall 26. When it 
reaches this level, the air pockets formed between ribs 28 during the 
liquid flow through the passageway buoys the closure upwardly causing the 
closure to rise with the rising liquid until it reaches its upper limit as 
shown to the right in FIG. 1. As the closure rises, the upward withdrawal 
of the piston from cavity 13 is in the suction or intake mode so as to 
draw tank liquid into space 13 as with the suction stroke of a pump, and 
is augmented by the head of water above the dispenser. In this condition, 
lip 22 is in engagement with bead 19 although, as mentioned above, no seal 
is effected by reason of such engagement since liquid is permitted to flow 
through slots 24. Nevertheless, a separation between the interior and 
exterior of the container is effected by the aforedescribed air pockets 
which thereby prevent the migration of chemical concentrate into the tank 
between flushes since cavity 13 is a dead space. Thus, direct 
communication between the liquid concentrate within the dispenser and the 
liquid in the tank is interrupted. 
A dispenser generally designated 31 in FIG. 2, is the same as dispenser 10 
in its operation but is slightly different in its construction. Like 
elements will therefore be identified by like reference numerals. A 
closure 32 of this dispenser is similar to closure 14 in that it has 
concentric annular walls 16 and 25 depending from an upper wall 26' and 
respectively spaced from the interior and exterior of the container so as 
to form a passageway 27. However, bottom wall 17 forming part of the 
piston of closure 14 is eliminated from closure 32 and the top of annular 
wall 16 is closed by wall 26' which interconnects walls 16 and 25. And, 
wall 25 is extended upwardly, as at 25a, from wall 26' so as to form, 
together with wall 26', a cavity 33 which functions similarly to that of 
cavity 18 for the retention of tank liquid during the tank flush mode. 
With such construction, walls 16 and 26' define a downwardly open cup or 
space 34 for entrapped air which is similarly formed in the pockets 
defined between ribs 28 during elevation of the closure. 
Another slight difference between dispensers 10 and 31 is that slots 24 may 
be eliminated in lip 22, and the undersurface of bead 19 may be formed as 
a valve seat, so that a seal is effected between engaging elements 19 and 
22 (as shown to the right of centerline 23 in FIG. 2) for further 
separating the liquid within the dispenser from the liquid without, 
thereby eliminating the migration of concentrate into the tank between 
flushes. 
The operation of dispenser 31 is similar to that of dispenser 10 in that, 
when the level of the tank liquid reaches the top of the dispenser at a 
level 35, during the tank refilling operation, liquid will have entered 
space 13 between cavity or cup 34 and the top of the chemical material in 
the container via passageway 27, so that the entrapped air within pockets 
29 (defined between ribs 28, as seen in FIG. 4) and within cup 34 
functions to elevate the dispenser closure as the flotation lift force 
exceeds the restraining force of the closure. An air pocket is maintained 
within space 34 during the tank refilling operation on the same principle 
that maintains an air pocket 29 in the spaces between ribs 28. Closure 32 
thereafter rises with the continued rise of the level of the tank liquid 
as it blends with the tank liquid retained within cavity 33. 
During the tank flush mode, the solid chemical material which dissolves 
into a liquid concentrate when the water in space 13 is expelled through 
passageway 27, in the direction of arrows shown to the left in FIG. 2, as 
the air cushion in space 34 forces the concentrated liquid chemical over 
upper edge 21 of the container while the dispenser closure is depressed 
downwardly. Such occurs when the falling tank liquid level reaches the top 
of closure 32 whereupon the reduce buoyancy of the entrapped air in the 
cells between ribs 28 and in cavity 34, together with the added weight of 
the liquid maintained in cavity 33, causes the closure to move downwardly 
together with the level of the tank liquid. The liquid concentrate is 
expelled by the moving air pocket in space 34 until stops 28 bear against 
upper edge 21 of the container. During this short downward stroke, the 
liquid concentrate is mixed with the receding tank liquid as it proceeds 
through the tank drain and into the toilet bowl. 
It should be noted that the height of the water reservoir in the top of the 
dispenser effects the timing of the movement of the dispenser in both 
directions. That is, the weight of water within cavity 18 or cavity 33 is 
effectively weightless when submerged. However, as the level of the tank 
water recedes, it becomes progressively more forceful at the same rate as 
the recessive rate of the tank level. Thus, if the top of the water 
reservoir is higher above the tank bottom, then the downward force of the 
water weight begins sooner in the flush cycle. Conversely, if the height 
of the top of the cavity is lowered toward the tank bottom, then the 
effect of the weight of trapped water in this cavity is delayed with 
respect to the closing of the tank valve. The weight of water trapped in 
cavity 18 or cavity 33 may be increased by enlarging the diameter of the 
water reservoir. 
Dispenser 36 shown in FIG. 3, with its closure in a locked down position 
upon the interengagement of threads 30 and 30' operates the same as 
dispenser 10 but differs slightly in its construction. Like elements will 
therefore be identified by like reference numerals. In the FIG. 3 
embodiment, ribs 28 are radially disposed on the inner surface of wall 25 
(see FIG. 4) similarly as in FIG. 1 except that they do not define 
downward limit stops. An annular wall 38 extends downwardly from wall 26 
and is spaced from both walls 25 and 16. Ribs 28 extend between walls 38 
and 25, and ribs 28' extend between walls 16 and 38. Wall 38 overlies 
upper edge 21 of the container and provides a seal in the locked-down 
position of FIG. 3. Ribs 28a are located on the inner surface of wall 25 
and permit enlarging the annular space defining flow passage 27 while 
preventing any cocking of the dispenser during its upward and downward 
movement. Wall 38 defines air pockets 29 and 29' together with ribs 28 and 
28', for the same purpose as discussed in FIG. 1. The bottom edge of 
annular wall 38 comes to rest against upper edge 21 of the container in 
the locked-down closure position but remains spaced above edge 21 at the 
lower limit position of the closure as when thread 30 abuts against the 
upper side of thread 30'. Lip 22 engages rib 19 for limiting the upward 
stroke of the piston. 
If the dispenser is not maintained vertical while being initially installed 
into the tank, the air within the dispenser cannot shift entirely to the 
high side thereof. Uneven buoyancy would thereby occur. Ribs 28 and 28' 
thus form baffles for trapping the air in annular cells or pockets 29a and 
29' which are shown in FIG. 4 including ports 37. 
The FIG. 5 embodiment of a dispenser 39 is similar to that of dispenser 31 
in FIG. 2 except that annular wall 38 extends downwardly from top wall 
26', and bores or ports 37 are located in wall 26' between walls 38 and 
25. Also, an annular wall 41 extends upwardly from wall 26' and defines 
with wall portion 25a an annular cavity 42. Thus, the tank water from this 
cavity 42 will purge the concentrate from annular space 27 into the tank 
through bores 37 without retaining any residual concentrate therein to be 
dissipated into the tank liquid on the tank fill cycle where dispenser 
wall 25 remains beneath the level of liquid in the tank at the lowest 
level. 
For each of the disclosed embodiments, at least one port 37 is located in 
the closure member for venting passage 27 as well as to facilitate the 
flushing of concentrate from the passage into the tank during the tank 
flushing mode. The dispenser is initially primed and its closure is 
permitted to rise each time with the rising tank liquid during the tank 
refill mode. And, as the level of tank liquid falls below top wall 26 of 
the closure, liquid flowing through port 37 flushes the concentrate from 
passage 27 into the tank. 
Ports 37 are sized so as to control the flow rate of the water 
therethrough, and may be designed to effect a lag in flow behind that of 
the rate of fall of the tank liquid level so as to provide added thrust 
against the air cushion in space 34, during the receding phase of the 
cycle. However, there is no net effect of this added volume on the tank 
refill cycle since the tank fill rate is sufficiently slow that passage of 
tank water upwardly through flow passage 27 is essentially unimpeded. It 
can be seen that even if the fill cycle were impeded, there would be no 
serious or deleterious effect unless and until the fill rate of the tank 
caused an inordinarily high flotation effect, lifting the assembly off of 
the bottom of the tank. The relative sizes of passage 27, air pockets 29a, 
29', spaces 29 and drain holes 37 permit considerable design options in 
achieving specific discharge modes and recharge cycles. 
Ports 37 may thus be located in alternate cells such as 29 for providing 
additional air cells 29a. However, ports 37 may likewise be provided in 
cells 29a of the FIG. 5 embodiment since a large air-filled cavity 34 is 
included in this dispenser. 
In the FIG. 6 embodiment, a dispenser 43 functions the same as dispenser 10 
but is of slightly different construction. Dispenser 43 includes a 
container 44 which is similar to container 11 except that it has a neck 
portion 45 defining a shoulder 46, and an outwardly extending annular bead 
47 provided on the neck portion adjacent an upper edge 48 thereof. Wall 16 
of piston 15 and wall 25 depend from top wall 26 and are respectively 
spaced inwardly and outwardly of the container so as to define passageway 
27. A skirt 49 likewise depends from wall 26 slightly outwardly of bead 
47, and has an annular inwardly extending lip 51 at the lower end thereof. 
This lip engages shoulder 46 so as to define a limit stop for the closure 
during its downward movement. Conversely, bead 47 forms an upper limit 
stop for the closure as lip 51 engages the bead. A valve seat 52 is formed 
along the undersurface of the bead so that, when the lip is engaged 
therewith, a liquid seal is formed between the interior and exterior of 
the container so as so assist in preventing migration and mixing of the 
liquid in the tank between flushes with the liquid chemical concentrate in 
chambers 13 beneath piston 15. Otherwise, the air pockets formed in spaces 
29 and 29a will form an effective separation between the interior and 
exterior of the container similarly as described with reference to FIG. 1. 
A one-piece dispensing closure is thereby formed which is actuated by the 
action of the rising and falling of the liquid in the tank for ingesting 
tank water within the container during the upward stroke of the piston and 
for together expelling liquid chemical concentrate from the container into 
flow passage 27 and into the tank as required, similarly as described for 
the operation of liquid dispenser 10. Upper and lower limit stops for the 
closure are respectively defined by bead 47 and shoulder 46 when engaged 
by lip 51. This lip is spaced from wall 26 a distance greater than the 
spacing of shoulder 46 from upper edge 48 so as to maintain spaces 29 and 
29a at the downward limit of the closure. Air pockets in these spaces are 
therefore assured of forming during the rising action of the closure. 
Wall 25 extends upwardly as at 25a so as to define an upper cavity or 
reservoir 18a in open communication with cavity 18. Ports 37 are located 
in upper wall 26 between walls 25 and 49 so as to permit water from cavity 
18a to purge the concentrate from passage 27 during the flush cycle, as in 
a manner described with reference to the earlier embodiments. 
A liquid dispenser 53, shown in FIGS. 7, 8 and 9, is similar to dispenser 
10 except that a container 54 is provided and has an upper thread 55 and a 
lower bead 56 respectively forming lower and upper limit stops for closure 
57. Piston 15, defined by walls 16 and 17, depends from upper wall 26 into 
the interior of the container through upper edge 21 to function similarly 
as in FIGS. 1 and 6. Passageway 27 is formed between container 54 and 
walls 25, 16 spaced therefrom, and space 29 forming an air pocket is 
located beneath top wall 26 and above the upper edge of the container. 
A bead 60 is formed on wall 25 for engagement with bead 56 to limit the 
upward movement of the closure as in FIG. 8, and a thread 58 is formed on 
wall 25 for engagement with thread 55 to limit the downward movement of 
the closure as in FIG. 7. Threads 55 and 58 are so positioned as to 
maintain space 29 at the downward limit of the closure so as to permit an 
air pocket to be formed therein during the liquid rising and closure 
rising action as in a manner described with reference to FIG. 1. Besides 
forming lower limit stops, threads 55, 58 permit closure 57 to be locked 
in place on container 54 (FIG. 9) upon relative rotation thereof. The 
contents of dispenser 53 are thus sealed within the container while 
storing or otherwise handling the dispenser when not in use. 
And, beads 56 and 60 may be continuous so that the lower surface of bead 55 
forms a valve seat. Thus, during engagement between the beads as in FIG. 
8, any migration and mixing of the liquid chemical concentrate in space 
13, with that of the liquid in the tank between flushes, is substantially 
avoided. 
Wall 25 is extended upwardly as at 25a to form an upper cavity or reservoir 
18a in open communication with cavity 18. An annular wall 38 extends 
downwardly from wall 26 and provides a flow channel for tank water drained 
from reservoir 18a in a manner to permit mixing with the effluent from 
within the container as the closure descends, thereby expelling 
concentrate outwardly beneath wall 25. The tank water from cavity 18a 
therefore purges the concentrate from flow passage 27, via ports 37, into 
the tank without retaining any residual concentrate therein to be 
dissipated into the tank liquid on the tank fill cycle when wall 25 
remains beneath the surface of the tank liquid at its lowest level. 
A liquid dispenser 59, shown in FIGS. 10, 10A, 11 and 12, is similar to 
dispenser 53 except that provision is made for adjusting the amount of 
liquid chemical discharged by varying the downward stroke of the closure. 
An uninterrupted annular bead 61 is provided on container 54, and beads 
62, each of a predetermined short length, likewise are provided on the 
container. Opposing pairs of beads 62 are spaced different distances from 
upper edge 21, and adjacent beads 62 are slightly spaced apart as shown in 
FIG. 11. An opposing pair of beads 63 are formed on wall 25 of the closure 
and extend toward the container for engagement with a selected pair of 
beads 62 upon rotation of the closure relative to the container into 
alignment therewith. As seen in FIG. 11, the length of beads 63 are 
slightly less than that of the cooperating pair of beads 62 so as to 
interfere with adjacent beads 62. FIG. 10A shows engagement between 
aligned beads 62 and 63 in a lowermost limit position of the closure. And, 
FIG. 10, to the left, shows a locked-down position of the closure as beads 
63 are made to engage beneath aligned beads 62. 
Vertical lugs 64 are provided on wall 25 of the closure and project 
inwardly between the spaced beads 62 to thereby provide an index 
adjustment and to prevent random rotational movement of the closure, thus 
maintaining the desired setting of the closure relative to the container. 
And, an annular uninterrupted bead 65 is provided on wall 25 and extends 
toward the container for engaging the undersurface of bead 61 to limit the 
upward movement of the closure and shown to the right in FIG. 10. The 
undersurface of bead 61 forms a valve seat so that, during engagement 
between beads 61 and 65, the interior of the container will be sealed from 
the exterior thereof. 
The downward stroke of the closure and its piston may thus be changed to 
adjust the concentration of the treatment by varying the amount of liquid 
chemical concentration during each cycle. The closure may be rotated 
relative to the container until lugs 63 are placed in alignment with a 
selected opposing pair of lugs 62. Lugs 64, which project into the spaces 
between adjacent beads 62, maintain such a rotated position of the 
closure. FIG. 10A illustrates engagement of lugs 63 and 62 to effect the 
longest possible downward stroke of the piston. Obviously, the shortest 
possible downward stroke of the piston will be defined upon rotation of 
the closure until lugs 63 are placed in alignment with that pair of lugs 
62 lying nearest upper edge 21. Lugs 62 therefore form downward limit 
stops with the piston, and bead 61 forms an upper limit stop. 
From the foregoing it can be seen that a simple and economical yet highly 
effective liquid dispenser is provided for positively controlling the 
discharge of liquid chemical concentrate from the interior of a container 
into the outflowing tank liquid only at the end of the tank flush cycle, 
thereby providing a greater concentration of chemical for performing the 
desired functions of cleaning, disinfecting and deodorizing. The dispenser 
makes use of a one-piece closure which is actuated by the action of the 
rising and falling of the tank liquid, and allows only a fixed amount of 
tank liquid to be admitted to the interior of the container after which a 
flow passage is closed off so as to prevent migration of the concentration 
from the container into the tank during the dwell time between flushes, 
thereby avoiding a needless waste of chemical by over-treating the tank 
liquid. 
The chemical concentrate in the container may be in solid form or in liquid 
concentrated form, and the closures of each of the embodiments may be 
locked in place over their containers by any conventional means such as by 
cooperating screw threads. Thus, the contents of the container may be 
enclosed against exposure to evaporated losses, moisture, absorption from 
humid environments, escaping odors while on shelves, etc. The dispenser 
may be likewise deactivated within the tank without the need to remove it 
from the tank. Several of the embodiments herein permit the amount of 
liquid chemical discharge to be adjusted from the container on each flush 
cycle, and a positive retention of the adjustment setting is conveniently 
provided. Waste by over-treatment of the tank liquid is prevented by the 
present invention by the inclusion of an automatic valving action at the 
end of the refilling mode which closes off the concentrate solution within 
the container from the liquid tank, thereby avoiding seepage into the 
tank. The dispenser effects a thrust of the chemical concentrate from the 
container into the tank by means of the piston having reciprocable biasing 
capabilities. The container may be refilled with chemical concentrate by 
simply inserting a fresh cake of solid chemical into the container, thus 
amounting to a recycling of the dispenser package. And, the dispensers are 
capable of ensuring that the tank water will purge the concentrate from 
the flow passage between the closure and the container during the tank 
emptying cycle. 
Obviously, many other modifications and variations of the invention are 
made possible in the light of the above teachings. For example, the 
dispenser is not limited to the discharging of a liquid chemical solution 
into a flush tank, but may be utilized for the discharge of liquid into 
other environments, and for the discharge of other fluids such as water 
softeners, rust inhibitors, algoecides, and the like. And, wall 17 of the 
piston in each embodiment may be located at a position intermediate the 
upper and lower ends of wall 16 so that an upwardly open cavity 18 and a 
downwardly open cavity 34 are both within annular wall 16 and are 
separated by wall 17. It is therefore to be understood that within the 
scope of the appended claims, the invention may be practiced otherwise 
than as specifically described.