Water dispenser abstract
A heating tank assembly for a hot water dispenser having a tank
body, an electric heating element, a magnetic switch, and a movable
float. The tank body has a plurality of walls and a main heating
chamber for storing and heating water. At least a portion of the
electric heating element is located within the main heating chamber
of the tank body. The magnetic switch is electrically connected
to the heating element and acts as a protective switch to the heating
element. The movable float is located within the tank body and has
a magnet that closes the magnetic switch when sufficient water is
present in the tank. The heating tank assembly may also include
at least one thermal cutout device. The thermal cutout device acts
as a backup and will shut off the heating element if the heating
element reaches a preset maximum temperature. The present invention
also includes a method for determining whether a heating tank assembly
of a hot water dispenser has little or no water by including a step
of moving the float to or from the magnetic switch and closing the
magnetic switch when sufficient water is present in the tank body.
The present invention also includes a method for manufacturing a
heating tank assembly of a hot water dispenser.
Water dispenser claims
What is claimed is:
1. A heating tank assembly for a hot water dispenser, comprising:
a plastic tank body having a main heating chamber for storing and
heating water, an expansion chamber, and an air collection chamber,
wherein said main heating chamber is in fluid communication with
the expansion chamber and the air collection chamber; an electric
heating element wherein at least a portion of said heating element
is located within said main heating chamber of said tank body; a
magnetic switch electrically connected to said heating element,
said magnetic switch located outside said main heating chamber of
said tank body; and a movable float located within said tank body,
said movable float having a magnet to close said magnetic switch
when sufficient water is in said tank.
2. The tank assembly of claim 1 wherein said tank body is made
of molded plastic.
3. The tank assembly of claim 1 wherein said magnetic switch is
a Reed switch.
4. The tank assembly of claim 3 wherein said magnetic switch is
normally open when said magnet of said movable float is not in close
proximity to said magnetic switch.
5. The tank assembly of claim 1 wherein said movable float has
an air pocket.
6. The tank assembly of claim 1 wherein said movable float is
made of plastic having a foaming agent.
7. The tank assembly of claim 1 wherein said movable float is
triangular.
8. The tank assembly of claim 1 wherein said movable float is
rectangular.
9. The tank assembly of claim 1 wherein said heating element has
a first portion outside the tank body and a second portion inside
the tank body, said heating tank assembly having at least one thermal
cutout device located in close proximity to the first portion of
the heating element and capable of shutting off the heating element
when the heating element reaches a preset temperature.
10. A hot water dispenser, comprising: a plastic tank body having
a main heating chamber for storing and heating chamber for storing
and heating water, an expansion chamber, and an air collection chamber,
wherein said main heating chamber is in fluid communication with
the expansion chamber and the air collection chamber; an electric
heating element to heat water in said main heating chamber of said
tank body, said heating element extending at least partially into
said heating chamber through a bushing mounted to a hole in said
tank body; and a switch electrically connected to said heating element,
said switch capable of determining whether little or no water is
present in said tank body, said switch inhibiting the activation
of said heating element if the tank body has little or no water.
11. The hot water dispenser of claim 10 wherein said switch is
a magnetic switch.
12. The hot water dispenser of claim 11 wherein said magnetic
switch is a Reed switch.
13. The hot water dispenser of claim 11 wherein said magnetic
switch is normally open.
14. The hot water dispenser of claim 13 wherein said hot water
dispenser further comprises a movable float located within said
tank body, said movable float having a magnet to close said magnet
switch when sufficient water is present in said tank.
15. The hot water dispenser of claim 14 wherein said movable float
is triangular.
16. The hot water dispenser of claim 14 wherein said movable float
is rectangular.
17. The hot water dispenser of claim 10 wherein said heating element
has a first portion outside the tank body, said hot water dispenser
having at least one thermal cutout device located in close proximity
to the first portion of the heating element and capable of shutting
off the heating element when the heating element reaches a preset
temperature.
18. The hot water dispenser of claim 10 further including a movable
float located within said tank body, said switch is a magnetic switch
located outside said tank body and said float includes a magnet
that activates said magnetic switch when sufficient water is in
said tank.
19. A heating tank assembly for a hot water dispenser, comprising:
a tank body having a plurality of walls and a main heating chamber
for storing and heating water; an electric heating element mounted
to said tank body, said heating element having a first portion located
outside the tank body and a second portion located inside the tank
body; and at least one thermal cutout device located in close proximity
to the first portion of the heating element and capable of shutting
off the heating element when the heating element reaches a preset
temperature, said thermal cutout device wrapped in insulating tape.
20. The tank assembly of claim 19 further comprising a magnetic
switch and a movable float, said magnetic switch electrically connected
to said heating element, said movable float located within said
tank body, said movable float having a magnet to close said magnetic
switch when sufficient water is in said tank.
21. The tank assembly of claim 20 wherein said magnetic switch
is located outside said tank body.
22. A heating tank assembly for a hot water dispenser, comprising:
a plastic tank body having a main heating chamber for storing and
heating water, an expansion chamber, and an air collection chamber,
wherein said main heating chamber is in fluid communication with
the expansion chamber and the air collection chamber; an electric
heating element wherein at least a portion of said heating element
is located within said main heating chamber of said tank body; and
a switch electrically, connected to said heating element, said switch
capable of preventing said heating element from energizing when
insufficient water is in said tank, said switch is mounted to said
tank body without placing a hole through said tank walls.
23. The heating tank assembly of claim 22 wherein said switch is
a magnetic switch.
24. The heating tank assembly of claim 22 wherein said switch comprises
a magnetic switch located outside of said tank body and a movable
float located inside said tank body, said movable float having a
magnet to activate said magnetic switch when sufficient water is
in said tank.
25. The heating tank assembly of claim 22 wherein said switch is
a thermal cutout device.
26. The heating tank assembly of claim 24 wherein said heating
element has a first portion outside said tank body and a second
portion inside said tank body, said thermal cutout device located
in close proximity to said first portion of said heating element,
said thermal cutout device capable of shutting off said heating
element when said heating element reaches a preset temperature.
Water dispenser description
FIELD OF INVENTION
The present invention relates generally to hot water dispensing
systems having a plastic heating tank. In particular, the present
invention relates to a water heating tank with a float switch sensor
and thermal cutout devices for protecting the tank when the tank
has little or no water.
BACKGROUND OF THE INVENTION
Hot water dispensers are known in the marketplace. As used herein,
"hot water" refers to water at temperatures at or about
190.degree. Fahrenheit (88.degree. Celsius), but at or below the
boiling point of water (212.degree. Fahrenheit/100.degree. Celsius).
Water at this high temperature can be made available at a dedicated
faucet for users needing hot water to make, for example, coffee,
tea, or cocoa. A typical dispenser heats water in a relatively small
tank that is situated below the sink on which the dedicated faucet
is mounted. The tank may have a capacity of 1/3 or 1/2 gallon (1.3
or 1.9 liters). The tanks are usually divided into multiple chambers,
such as a main chamber and an expansion chamber. Water is heated
electrically by a heating element in the main chamber. The expansion
chamber is contiguous with the main chamber and contains water that
is initially heated in the main chamber and allowed to expand into
the expansion chamber to preclude pressure buildup generated by
heating the water.
Most known water heating chambers and tanks utilize metal fabricating
wherein several pieces of metal must be integrated together to create
separate air and watertight chambers. The fabrication of metal tanks
is labor intensive and requires expensive cleaning operations. Metal
tanks are also susceptible to leaks because the tank is made from
several pieces of metal.
As a result, a hot water dispenser with a plastic tank was developed
and is the subject of application Ser. Nos. 09/396387 and 09/026070
which are owned by the assignee and incorporated herein by reference
in their entirety. As explained in those applications, the plastic
tank is cheaper and easier to fabricate. The plastic tank, however,
is vulnerable to damage when the heating element is activated when
little or no water is present in the tank. For instance, damage
is likely to occur during an accidental "dry start," which
happens after installation of the tank and before water has been
introduced into the system. Hot water dispensers are typically not
sold with an on/off switch, so once the unit is plugged in, the
heater will be energized. Damage may also occur during a rare "boil
dry" condition, when the water in the tank boils until the
water level becomes too low. Damage to a tank may occur very quickly,
within the first minute or two after the heating element is energized.
By the time a person or system recognizes the problem, it is typically
too late to avoid damage.
Accordingly, a need exists to prevent damage to a tank when little
or no water is present in the tank. Application Ser. No. 09/479190
which is owned by the assignee and incorporated herein by reference
in its entirety, discloses a tank for a hot water dispenser that
includes at least one heat dissipation plate. Heat is diverted from
the walls of the tank to the heat dissipation plate. The present
invention, however, prevents damage to the tank by inhibiting the
activation of the heating element when little or no water exists
in the tank. By inhibiting the heating element from energizing,
the potential for excessive heat generation is eliminated.
SUMMARY OF THE INVENTION
To that end, the present invention provides a heating tank assembly
for a hot water dispenser having a tank body, an electric heating
element, a magnetic switch, and a movable float. The tank body has
a plurality of walls and a main heating chamber for storing and
heating water. At least a portion of the electric heating element
is located within the main heating chamber of the tank body. The
magnetic switch is electrically connected to the heating element
and acts as a protective switch to the heating element. The movable
float is located within the tank body and has a magnet that closes
the magnetic switch when sufficient water is present in the tank.
The tank body and movable float are preferably made of molded plastic.
The float may, alternatively, be made of plastic with a foaming
agent. The magnetic switch is preferably a Reed switch. In one embodiment,
the magnetic switch is normally open. As sufficient water is added
to the heating tank assembly, the float moves within proximity to
the magnetic switch and closes the switch, enabling the heating
element to be energized. The magnetic switch, however, may also
be normally closed. In this embodiment, the float is already in
close proximity to the switch when little or no water is present
in the tank. As sufficient water is added to the heating tank assembly,
the float moves away from the magnetic switch and closes the switch,
enabling the heating element to be energized.
The heating tank assembly may also include at least one thermal
cutout device. The thermal cutout device is located in close proximity
to a portion of the heating element that is outside the tank body.
The thermal cutout device acts as a thermal fuse and can shut off
the heating element when the heating element reflects a preset temperature.
In another embodiment, the present invention provides a hot water
dispenser having a plastic molded tank body, an electric heating
element, and a switch. The plastic molded tank body has a plurality
of walls and a main heating chamber for storing and heating water.
The heating element extends at least partially into the heating
chamber through a bushing mounted to a hole in the tank body. The
switch is electrically connected to the heating element and is capable
of determining whether little or no water is present in the tank
body. The switch inhibits the activation of the heating element
if the tank body has little or no water.
In a further embodiment, the present invention is a method for
determining whether a heating tank assembly of a hot water dispenser
has little or no water. The method includes providing a unitary
plastic molded tank body, an electric heating element, a magnetic
switch, and a movable float. The tank body has a heating chamber,
and at least a part of the heating element is located within the
heating chamber. The magnetic switch is electrically connected to
the heating element. The movable float is located within the tank
body and has a magnet. The method includes the steps of moving the
float within proximity to the magnetic switch and closing the magnetic
switch when sufficient water is present in the tank body. In another
embodiment, the method includes the alternative steps of moving
the float away from the magnetic switch and closing the magnetic
switch when sufficient water is present in the tank body.
In yet another embodiment, the present invention is a method for
manufacturing a heating tank assembly of a hot water dispenser.
The method includes the steps of providing a unitary molded plastic
tank body having a heating chamber, providing an electric heating
element, mounting the electric heating element to the tank body,
providing a magnetic switch, mounting the magnetic switch to the
tank body, electrically connecting the magnetic switch to the heating
element, providing a float that has a magnet, and positioning the
float in the tank body such that the magnet of the float closes
the magnetic switch when sufficient water is present in the tank
body.
In another embodiment, a heating tank assembly is provided and
includes a tank body, an electric heating element, and at least
one thermal cutout device. The tank body has a plurality of walls
and a main heating chamber for storing and heating water. The heating
element is mounted to the tank body and has a first portion located
outside the tank body and a second portion located inside the tank
body. The thermal cutout device is located in close proximity to
the first portion of the heating element and is capable of shutting
off the heating element when the heating element reaches a preset
temperature. The thermal cutout device may also be wrapped in insulating
tape to prevent shorting to the heating element.
BRIEF DESCRIPTION OF THE DRAWINGS
Other objects and advantages of the invention will become apparent
upon reading the following detailed description and upon reference
to the drawings.
FIG. 1 is an exploded view of a heating tank assembly of a hot
water dispensing system.
FIG. 2 is a cross-sectional view of one embodiment of the present
invention showing a heating tank assembly mounted to a dispensing
faucet.
FIG. 3 is an enlarged view of a venturi valve aspirator of the
hot water dispensing system.
FIG. 4 is an assembly view of the temperature control system of
the hot water dispensing system.
FIG. 5 is an exploded view of a temperature control system of a
heating tank assembly.
FIG. 6 is a perspective view of the inside of the heating tank
assembly for one embodiment of the present invention.
FIG. 7 is a cross-sectional view of a float for one embodiment
of the present invention.
FIG. 8 is a cross-sectional side view of a heating tank assembly
for one embodiment of the present invention.
FIG. 9 is a cross-sectional view of another embodiment of the present
invention showing a heating tank assembly mounted to a dispensing
faucet.
FIG. 10 is a perspective view of a float for another embodiment
of the present invention.
FIG. 11 is a cross-sectional view of the float in FIG. 10.
While the invention is susceptible to various modifications and
alternative forms, a specific embodiment thereof has been shown
by way of example in the drawing and will herein be described in
detail. It should be understood, however, that it is not intended
to limit the invention to the particular forms disclosed but, on
the contrary, to cover all modifications, equivalents, and alternatives
falling within the spirit and scope of the invention as defined
by the appended claims.
DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
FIG. 1 depicts an exploded view of a heating tank assembly 100.
The heating tank assembly includes, among other things, a tank body
105 Emaweld.RTM. strands 110 and 155 a tank cover 115 a heating
element 120 a temperature control system 160 a venturi valve 210
a float 400 a magnetic switch 405 and thermal cutout devices (TCO)
135.
The tank body 105 is formed from a plastic material and is comprised
of two side walls 180 a top wall 185 a bottom wall 190 and a
rear wall 195 containing two holes or orifices 197. The design of
one embodiment of the present invention is described as a one piece
plastic tank construction. Each tank chamber, the venturi valve
and all inlet/outlet ports are all injection-molded using conventional
techniques and preferably composed of plastic. The one piece plastic
molded configuration of one embodiment of the present invention
greatly reduces the cost and labor required to make the tank, as
well as significantly reducing the potential for leaks. The plastic
tank is considered to be one piece after a tank cover 115 and a
venturi valve 210 are integrally heat-bonded to the five sided tank
body 105 using an Emabond.RTM. electromagnetic welding system. The
Emabond.RTM. welding system is commercially available from the Ashland
Chemical Company of Columbus, Ohio.
The Emabond.RTM. welding system utilizes ferromagnetic material
called Emaweld.RTM. that is placed between the tank body 105 and
the tank cover 115. The Emaweld.RTM. sections are spaghetti-type
bonding strands that are subjected to alternating magnetic fields
that cause the strands to melt and fuse the tank body 105 to the
tank cover 115 creating structural, hermetic, pressure-tight, and
leak-proof seals. The heat-bonded tank cover 115 eliminates the
need for a sealing system with additional materials and components,
ie., fasteners, sealing materials, etc. The elimination of metal
components from the construction of the plastic tank further reduces
heat loss from the water through the high heat conductivity of metal.
Before the tank cover 115 is heat-bonded to the tank body 105 silicone
cylindrical bushings 170 the heating element 120 and the float
400 are inserted. As shown in FIG. 1 the silicone cylindrical bushings
170 are inserted into two holes or orifices 197 in the rear wall
195 of the tank body 105 and the heating element 120 is placed
inside the main heating chamber 200 of the tank body 105. A metal
washer 127 is welded to each arm 125 of the heating element 120.
The two arms 125 of the heating element 120 are inserted into and
extended through the silicone cylindrical bushings 170 until the
metal washers 127 prevent further passage of each arm 125 of the
heating element 120 through the silicone cylindrical bushings 170.
In one embodiment, as shown in FIG. 2 the float 400 is retained
on a pivot post 410 by a retaining ring 420.
Because the tank body 105 is made of plastic construction, a unique
system for sensing the water temperature and the water level inside
the water heating chamber is also provided. The water temperature
is sensed using a metal temperature sensing bracket 130 located
on the outside of the tank body 105. The metal temperature sensing
bracket 130 is crimped to the two arms 125 of the heating element
120 as described below. It has been contemplated, in accordance
with the present invention, that the temperature bracket 130 may
be composed of copper or a composite of various metals. Two orifices
137 in the temperature bracket 130 correspond to and are aligned
with the respective two orifices 197 in the rear wall 195 of the
tank body 105. The two arms 125 of the heating element 120 extend
through the silicone cylindrical bushings 170 through the two orifices
197 in the rear wall 195 of the tank body 105 and emerge on the
outside of the tank body 105. The two arms 125 subsequently reach
through the two corresponding orifices 137 of the temperature bracket
130.
A sheath 175 is the outer covering of the entire heating element
120 and is composed of heat conducting metal. The sheath is composed
of metal to assist the temperature control system 160 in responding
quickly to changes in the water temperature with the tank body 105.
A crimping machine (not shown) crimps the outside of the two orifices
137 of the temperature bracket 130 onto the sheath portion 175 at
the end of the two arms 125 of the heating element 120 to secure
the temperature bracket 130 and the tank body 105 to the heating
element 120. Crimping the orifices 137 of the temperature bracket
130 to the heating element 120 ensures a good metal connection between
the temperature bracket 130 and the sheath 175. Because the temperature
bracket 130 and the sheath 175 are excellent heat conductors, the
temperature bracket 130 is able to detect changes in the water temperature
through the heating element 120. A good connection between the temperature
bracket 130 and the sheath 175 is needed to ensure that a thermostat
145 can accurately calculate and control the temperature of the
water on the inside of the tank. It is beneficial for the thermostat
145 to maintain a temperature setting within +/-1 degree. The thermostat
145 is attached to the temperature bracket 130. A thermostat insulator
pad 147 is used to insulate the thermostat 145 from the temperature
bracket 130. The insulator pad 147 had a cutout for a sensor 148.
The sensor 148 is mounted to the back of the board of the thermostat
145 and senses the temperature of the temperature bracket 130 that
correlates with the water temperature inside the tank body 105.
A suitable sensor 148 is described in U.S. Pat. No. 5955793 which
is incorporated herein by reference in its entirety. The sensor
148 and thermostat 145 maintain the water temperature inside the
tank body 105 at around 190.degree. Fahrenheit (88.degree. Celsius),
but always at or below the boiling temperature (212.degree. Fahrenheit/100.degree.
Celsius) of water. A heat sink 149 is also provided to dissipate
excess heat generated in the temperature bracket 130.
As shown in FIG. 4 a small tube 163 extends from each orifice
137 of the temperature bracket 130. A cold pin 165 extends from
a position exterior to the tube 163 through the tube 163 and into
the inside of the heating element 120. It is preferable that the
cold pin 165 extends from about 0.5 inches to about 1.5 inches past
the tube 163 and into the heating element 120 and, more preferably,
that the cold pin extends about 1 inch past the tube 163 and into
the heating element 120. A heater wire (not shown) within the heating
element 120 on the interior of the tank body 105 is connected to
the end of the cold pin 165 that extends into the heating element
120 as described above. It is contemplated, in accordance with
the present invention, that the heater wire can be welded or crimped
to the end of the cold pin 165.
When the temperature drops below a certain preset level, the thermostat
145 (via a wire connecting the thermostat 145 and the cold pin 165)
directs a flow of current through the cold pin 165 and into the
heater wire within the heating element 120. The current flows through
the wire within the heating element 120 and exits at the cold pin
at the other arm 125 of the heating element 120. Due to the resistive
characteristics of the wire, the current passing through the wire
produces heat, which, in turn, causes the temperature of the heating
element 120 to increase. This subsequently causes the temperature
of the water inside the tank body 105 to increase.
A packing material is placed within the tube 163 to secure the
heater wire and the cold pin 165 within the tube 163 and to insulate
the heater wire from touching the walls of the heating element 120.
The packing material is packed using a vibration method to tightly
compress the packing material. It is contemplated, in accordance
with the present invention, that an example of the packing material
used within the tube is magnesium oxide in powder form. A sealing
compound is placed outside the packing material to seal the packing
material and retard the absorption of moisture. One example of the
sealing material used in accordance with the present invention is
silicone liquid.
FIGS. 4 and 5 are assembled and exploded views of the temperature
control system 160. The metal temperature sensing bracket 130 is
located on the outside of the tank body 105. The thermostat 145
is connected to the temperature bracket 130.
A wire harness (not shown) allows the temperature control system
160 to obtain electrical power.
In determining whether sufficient water is present in the heating
tank assembly 100 before energizing the heating element 120 the
heating tank assembly 100 has a float 400 and a magnetic switch
405. Determining whether the heating tank assembly 100 has little
or no water is important before activating the heating element 120.
Since the tank body 105 and components are made from plastic, the
wattage of the heater element 120 needs to be controlled to prevent
the tank body 105 and components from melting or otherwise deforming.
For instance, a tank body 105 may be damaged during an accidental
"dry start," which happens when the heating element is
activated after installation of the tank and before water has been
introduced into the system.
Accordingly, referring to FIGS. 2 5 and 6 a movable float 400
is used to determine if sufficient water is present in the heating
tank assembly 100. In one embodiment of the present invention, the
float 400 is triangular in shape and rotates on a pivot post 410.
The float 400 is retained on the pivot post 410 by a retaining ring
420. As water enters the heating tank assembly 100 the float 400
rises until it reaches a stop post 415. The pivot post 410 and the
stop post 415 may be formed as part of the injection molding process
of the tank body 105. Forming the posts 410 and 415 as part of the
tank body 105 eliminates the need for additional holes or openings,
reducing the chances of leaks.
Referring to FIG. 7 in one embodiment, the float 400 contains
an air pocket 425 and a magnet 430. The float 400 may be made of
plastic or other non-metallic material. The float 400 is sealed
so that air is retained in the pocket 425 when the heating tank
assembly 100 is filled with water. In alternative embodiments, the
air pocket 405 may be replaced with Styrofoam or other floatable
materials. The float may also be made of plastic with a foaming
agent to further assist the float to rise when water is added to
the tank body 105.
As shown in FIG. 4 a magnetic switch 405 is mounted to the temperature
control system 160. The magnetic switch 405 is electrically coupled
to the heater element 120 and acts as a protective switch for the
heater element 120. The magnetic switch 405 may be a Reed switch
which is commercially available from Hasco Components International
Corp. of Bellerose Village, New York. A Reed switch is a proximity
sensor that detects the presence of a magnet. The Reed switch has
two ferromagnetic contacts that can either be normally open or normally
closed.
In one embodiment of the present invention, the magnetic switch
405 is normally open. When little or no water is present in the
heating tank assembly 100 the magnet 430 is not located in close
proximity to the magnetic switch 405 and the switch remains open
(as shown in FIG. 6). When the magnetic switch 405 is open, no power
can be applied to the heating element 120. As water fills the heating
tank assembly 100 the float 400 (and magnet 430) rises to the stop
post 415 and a magnetic field is introduced to the magnetic switch
405 by bringing the magnet 430 into proximity with the magnetic
switch 405 as shown in FIGS. 2 and 8. The presence of a magnetic
field attracts the two contacts in the normally open magnetic switch
405 causing the switch to close. When the magnetic switch 405 is
closed, power may be applied to the heating element. The magnetic
switch 405 is operational with a variety of DC voltages.
In another embodiment, the magnetic switch 405 is normally closed.
In this embodiment, however, the magnet 430 is already in close
proximity to the magnetic switch 405 when little or no water is
present in the heating tank assembly 100. Thus, the presence of
a magnetic field repels the two ferromagnetic contacts of the magnetic
switch 405 and the switch opens. When the magnetic switch 405 is
open, no power may be applied to the heating element 120. As water
fills the heating tank assembly 100 the float 400 (and magnet 430)
rises and the magnetic switch 405 closes. When the magnetic switch
405 is closed, power may be applied to the heating element 120.
The float 400 may be of other shapes. For instance, referring to
FIGS. 9 10 and 11 in a further embodiment of the present invention,
a float 500 is rectangular or cubed and allowed to traverse up and
down along tracks 535. The float 500 is constrained in the upward
and downward positions by stop posts 515. The float may also be
spherical or elliptical and allowed to traverse up and down tubular
walls.
The benefit of using a float and magnetic switch is that no additional
holes or openings are needed in the tank body 105 reducing the
chances of leaking.
Thermal cutout devices (TCO) 135 provide excellent temperature
sensing capabilities and may be used as a backup to float 400. The
TCO's are a limiting thermostat that protect the tank from abnormal
conditions, such as no or low water conditions in the tank, by shutting
off the heating element when the temperature reaches a preset maximum
allowable temperature for the tank and/or system. In one embodiment,
the TCO's 135 are mounted via leads 138 to the thermostat 145. As
shown in FIG. 4A, the leads 138 are bent inward so that the TCO's
135 are next to the exterior surface of tube 163. As described above,
the tube 163 is a portion of the heating element 120 that expands
outside the tank body 105. In this embodiment, the TCO's 135 are
wrapped in insulating tape to prevent shorting to the heating element
120. Examples of suitable insulating tape include Kaptom/Nomex spiral
tape and teflon tape. In another embodiment, the TCO's 135 are mounted
to the temperature bracket 130 and sense the temperature of the
water in the same manner as the thermostat 145 as described above.
The TCO's 135 conventional and low cost temperature sensing devices,
are non-invasive in that they eliminate the need to put yet another
hole in the tank and provides a separate temperature sensor. Thus,
a simpler design is created, further reducing the cost of the heating
system. The TCO's 135 are commercially available from Therm-O-Disc,
Inc., of Mansfield, Ohio.
FIG. 2 depicts a cross-section of an assembled hot water dispensing
system mounted to a dispensing faucet. The illustrated hot water
dispensing system comprises a tank body 105 divided into a main
heating chamber 200 and an expansion chamber 205 in fluid communication
with and communicatively coupled to the main heating chamber 200.
The tank body 105 includes an internal wall 285 separating the main
heating chamber 200 from the air collection chamber 215 and another
internal wall 290 separating the expansion chamber 205 from both
the main heating chamber 200 and the air collection chamber 215.
The bottom of the internal wall 285 includes an opening 220 to provide
fluid communication between the main heating chamber 200 and the
air collection chamber 215.
An undesirable feature of previously manufactured hot water dispensing
systems arises when the water level in the expansion chamber drops
to a level low enough for air to be drawn in through aspirator lateral
hole(s) from the vented expansion chamber. In one embodiment of
the present invention, the air collection chamber 215 is positioned
within the tank body 105 residing generally below the expansion
chamber 205 and adjacent to the main heating chamber 200. The incoming
water supply line 245 provides water at line pressure to the plastic
venturi valve 210 located within the expansion chamber 205 whenever
a user actuates the operating handle 280 of the hot water faucet
270. Arrows in FIG. 2 indicate the flow direction of the water.
The venturi valve 210 directs entering water into the top 217 of
the air collection chamber 215. The venturi valve is positioned
within the expansion chamber 205 and is embedded to the tank through
use of the previously described Emabond.RTM. welding system. Specifically,
in one embodiment of the present invention, the tank body 105 as
shown in FIG. 1 comprises an orifice 150 with a vertical rim extending
away from the orifice 150. The venturi valve 210 is placed through
the orifice 150 and situated within the expansion chamber 205 as
shown in FIG. 2. After the venturi valve 210 is inserted, a flange
of the venturi valve 210 is disposed around the vertical rim of
the orifice 150 creating a pocket between the flange of the venturi
valve 210 and the vertical rim of the orifice 150. Referring back
to FIG. 1 an Emaweld.RTM. section 155 is installed within this
pocket to embed the venturi valve 210 integral to the tank.
Referring to FIG. 2 in order to obtain hot water for consumption,
a user actuates the operating handle 280 of the faucet 270. A supply
line infeed valve 260 of the faucet is opened and closed by actuating
an operating handle 280 of the faucet 270. It is contemplated, in
accordance with the present invention, that user-initiated raising,
pushing, or turning can actuate the operating handle 280. Actuating
the operating handle 280 causes water to be fed into the incoming
water supply line 245 through the tank inlet 240 and into the
venturi valve 210 located within the expansion chamber 205. Water
in the main heating chamber 200 is heated by the heating element
120 and allowed to expand into the expansion chamber 205 through
the venturi valve 210 and, subsequently, the lateral hole 320 during
times when water is being heated and expanded. It is contemplated,
in accordance with the present invention, that more than one lateral
hole may exist on the venturi valve 210. Water from the main heating
chamber 200 does not expand into the expansion chamber 205 when
water from the incoming water supply line 245 is traversing the
venturi valve 210.
After water enters the venturi valve 210 from the incoming water
supply line 245 negative pressure develops in the venturi valve
210 relative to the pressure in the expansion chamber 205. The negative
pressure in the venturi valve 210 causes aspiration of hot water
from the expansion chamber 205 into the air collection chamber 215.
A jet stream mixture of hot water from the expansion chamber 205
and cold water from the incoming water supply line 245 is then projected
from the venturi valve 210 into the top of the air collection chamber
215. When the expansion chamber 205 is emptied of water, air begins
to be aspirated from the expansion chamber 205. Because air is lighter
than water, air is captured in the air collection chamber 215. Any
air collected in the air collection chamber 215 is subject, at its
lower opened end, to hydrostatic pressure from the water. The air
collection chamber 215 can be filled sufficiently deep with air
at a pressure that will balance against the water pressure in the
tank.
As the collected air in the air collection chamber 215 pushes against
the weight of the water in the tank, a positive pressure develops
in the air collection chamber 215 and counters a vacuum pressure
that develops in the venturi valve 210. The aspiration of air from
the expansion chamber 205 slowly decreases with the increasing air
pressure in the air collection chamber 215. The aspiration of air
ceases when the air pressure in the air collection chamber 215 equals
the vacuum pressure in the venturi valve 210. Water from the incoming
water supply line 245 will still be fed into the venturi valve 210
as long as the faucet valve remains open.
After the water from the incoming water supply line 245 and the
expansion chamber 205 is forced into the air collection chamber
215 through the venturi valve, the water arrives at the main heating
chamber 200 via an opening 220 at the lower end of the air collection
chamber 215. Hot water is then forced out of the main heating chamber
200 through the hot water line 235 and into the faucet 270 for
consumer usage. The minimum square surface area of the water within
the air collection chamber 215 is important. The square surface
area of the water in the air collection chamber 215 is indirectly
related to the amount of pressure required in the air collection
chamber 215 and into the main heating chamber 200. The smaller the
square surface area of the water, the greater the pressure that
is required to force water out of the expansion chamber 205.
The air collection chamber 215 is located below the level of the
expansion chamber 205 and is communicatively coupled to the main
heating chamber 200. In one embodiment of the present invention,
the air collection chamber 215 is rectangular and narrow relative
to the main heating chamber 200. It is contemplated, in accordance
with the present invention, that the air collection chamber 215
can be cylindrical or any other shape that would permit the passage
of water as described in the present invention. It is also contemplated
that the air collection chamber 215 could be about the same size
or larger than the main heating chamber 200.
It is foreseeable, but undesirable, for the venturi jet velocity
pressure to be extreme enough to drive collected air out of the
bottom of the air collection chamber 215 and into the main heating
chamber 200. This action is precluded in cases where such action
could occur by installing a plastic deflector baffle 219 proximate
to the exit end 340 of the venturi valve 210. The plastic deflector
baffle 219 is arranged such that the venturi jet of water from the
exit end 340 of the venturi valve 210 is impinges upon the plastic
deflector baffle 219 to dissipate the kinetic energy of the water
and prevent air from exiting the air collection chamber 215 through
the opening 220 at the bottom of the internal wall 285. After impinging
upon the plastic deflector baffle 219 the air and water separate.
Without the baffle, air exiting the air collection chamber 215 and
entering the main heating chamber 200 would rise to the top of the
main heating chamber, and bubbles of air would dispense with the
outflowing hot water and produce undesired spitting and surging
of air bubbles intermixed with the hot water exiting the main heating
chamber 200 for consumer use. Instead of exiting the tank from the
main heating chamber 200 air in the air collection chamber 215
must remain in the air collection chamber 215 to provide the necessary
counterpressure to prohibit further aspiration of air from the expansion
chamber 205. The plastic deflector baffle 219 of the present invention
ensures that air will not depart from the air collection chamber
215 and enter the main heating chamber 200.
Maintaining the proper distance 335 between the exit end 340 of
the venturi valve 210 and the plastic deflector baffle 219 will
ensure elimination of air bubbles in the water leaving the tank
for consumer usage. If the distance 335 from the exit end 340 of
the venturi valve 210 to the plastic deflector baffle 219 is too
small, water exiting the venturi valve 210 will bounce back at itself
and change the aspiration pressure in the venturi valve 210. If
the distance 335 is too large, the water exiting the venturi valve
210 will travel around the plastic deflector baffle 219 and render
the baffle ineffective. The distance 335 from the exit end 340 of
the venturi valve 210 to the plastic deflector baffle 219 is preferably
from about 0.1 inches to about 0.8 inches, more preferably from
about 0.2 inches to about 0.4 inches, and most preferably about
0.25 inches. In one embodiment of the present invention, the plastic
deflector baffle 219 is mounted in the air collection chamber 215
with bypass openings around the plastic deflector baffle 219 so
the jet stream water can flow into the main heating chamber 200.
By way of example and not limitation, the pressure may be 3 psi
in the air collection chamber 215 and 3.1 psi at the top 217 of
the air collection chamber 215.
Water enters from the incoming water supply line 245 and continues
through a supply line infeed valve 260 through the tank inlet 240
and into the main heating chamber 200. Hot water is delivered to
the spout outlet 275 of the faucet 270 from the is upper region
of the main heating chamber 200 by way of the tank outlet 230 and,
subsequently, the hot water line 235 which leads from the tank outlet
230 to the hot water spout outlet 275. The expansion chamber 205
is vented to the atmosphere by way of a tube 250 whose lower end
is exposed to the interior of the expansion chamber 205 and whose
upper end is opened to the atmosphere through the interior vent
255 of the faucet 270. In addition to preventing pressure above
atmospheric pressure from developing in the expansion chamber 205
venting prevents a buildup of pressure in the main heating chamber
200 as discussed below. The tank has a conventional draining device
225.
If a user draws no hot water from the tank for an extended period
of time, the water in the main heating chamber 200 and the expansion
chamber 205 will be substantially evenly heated. When hot water
is drawn from the tank, it must necessarily be replenished with
cold supply water. This allows a new heating cycle inflow of cold
supply water to the tank from the incoming water supply line to
effectuate an emptying of the expansion chamber 205 of water to
provide a volume for incoming cold supply water to expand into as
it is heated. Admitting replenishment supply water concurrently
with emptying of the expansion chamber 205 is accomplished with
a venturi valve 210. This venturi valve is shown in FIG. 2 and enlarged
in FIG. 3.
As shown in FIG. 3 the venturi valve 210 is mounted in the expansion
chamber 205. Cold supply water flows through the incoming water
supply line 245 and through a bore 305 of the venturi valve. This
cold supply water imposes pressure on the inlet 310 of a venturi
orifice 315. Restricting the flow of the water by way of the small
diameter orifice 315 results in a velocity increase in the orifice
and, as a result, a jet of water emerges from the exit end 325 of
the orifice. Consonant with Bernoulli's principle, the increase
in velocity in the orifice is accompanied by a decrease in water
pressure relative to the pressure of the hot water in the expansion
chamber 205. Hot water initially arrives at the expansion chamber
205 by expanding from the main heating chamber 200. Consequently,
hot water from the expansion chamber 205 is drawn into the jet stream
through the lateral hole 320 of the venturi valve 210 as described
above. The stream of mixed hot and cold water, when is discharged
from the exit end 325 of the orifice, is at a pressure well below
supply line pressure, but is still sufficiently high to force hot
water out of the main heating chamber 200 through the tank outlet
230 and into the hot water line 235 for subsequent user consumption.
While the present invention has been described with reference to
one or more particular embodiments, those skilled in the art will
recognize that many changes may be made thereto without departing
from the spirit and scope of the present invention. Each of these
embodiments and obvious variations thereof is contemplated as falling
within the spirit and scope of the claimed invention, which is set
forth in the following claims. |