Note: Descriptions are shown in the official language in which they were submitted.
CA 2960258 2017-03-09
INSTANT ELECTRODE WATER HEATER
FIELD OF THE INVENTION
The present invention relates to electric water heaters, and more particularly
to an instant
electrode water heater that is compact and provides hot water at a
substantially high speed and
efficiency.
BACKGROUND OF THE INVENTION
Due to high - and further increasing - energy costs, there is an increasing
demand in energy
efficient electric water heaters. In particular, there is an increasing demand
in instant ¨ or on-
demand ¨ electric water heaters that heat water only when hot water is being
used. Since the
instant electric water heaters are more energy efficient and use less space
than storage tank
electric water heaters, they are preferred for various household and
industrial applications such
as, for example, showers, and appliances such as, for example, coffee makers,
dish washers, and
washing machines.
Most prior art tankless water heater systems use resistance type electric
heating elements to heat
the water. A major disadvantage of tankless water heater systems utilizing
resistance type electric
heating elements is that the elements themselves have substantial thermal mass
and thermal
resistance, substantially reducing the speed the water is heated, especially
when the water flow is
started. Since the water must flow through the heater before the heating
element is activated and
the heating element requires time to heat the water, there is first cold water
flowing out of the
heater, which is particularly a disadvantage in applications without a drain
such as, for example,
coffee makers.
The alternative to using heating elements for heating the water is to pass an
electric current
through the water by passing it between two electrodes between which an AC
voltage exists,
known as Direct Electrical Resistance (DER) heating. Unfortunately, existing
instant electrode
water heaters have numerous disadvantages: they are highly complex, rendering
them expensive
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to manufacture and difficult to implement in a compact fashion; the hot water
temperature is
difficult to control; and, they have a relatively high lifetime cost since the
complete heater has to
be replaced when the electrodes are no longer functional due to corrosion
and/or mineral
deposition.
It is desirable to provide an instant electrode water heater that is simple
and compact.
It is also desirable to provide an instant electrode water heater that
provides hot water at a
substantially high start-up speed and efficiency.
It is also desirable to provide an instant electrode water heater that enables
substantially accurate
control of the hot water temperature.
It is also desirable to provide an instant electrode water heater that enables
simple replacement of
the electrodes.
SUMMARY OF THE INVENTION
Accordingly, one object of the present invention is to provide an instant
electrode water heater
that is simple and compact.
Another object of the present invention is to provide an instant electrode
water heater that
provides hot water at a substantially high start-up speed and efficiency.
Another object of the present invention is to provide an instant electrode
water heater that
enables substantially accurate control of the hot water temperature.
Another object of the present invention is to provide an instant electrode
water heater that
enables simple replacement of the electrodes.
According to one aspect of the present invention, there is provided an instant
electrode water.
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The instant electrode water heater comprises a housing for containing water
therein with the
housing having a water inlet and a water outlet. A plurality of electrode
plates is disposed inside
the housing. The electrode plates are placed such that the electrode plates
are oriented parallel to
each other and have a predetermined distance between two successive electrode
plates for
directing water received at the water inlet through successive channels, with
each channel being
formed by two successive electrode plates, to the water outlet. A plurality of
electric contacts is
disposed in the housing such that each electric contact is in a touching
relationship with a
respective electrode plate for providing AC electric power thereto. Electric
control circuitry is
connected to the electric contacts for controllably providing electric power
thereto.
According to the aspect of the present invention, there is provided an instant
electrode water
heater. The instant electrode water heater comprises a housing having a water
inlet and a water
outlet and forms a cavity therebetween. An electrode cartridge having a
plurality of electrodes
therein is removably disposed in the cavity. A cover is removably mounted to
the housing in a
water sealed fashion for covering the cavity with the electrode cartridge
disposed therein. Electric
control circuitry is connected to the electrodes for controllably providing AC
electric power
thereto.
According to the aspect of the present invention, there is provided an instant
electrode water
heater. The instant electrode water heater comprises a housing having a water
inlet and a water
outlet and forms a cavity therebetween. A plurality of electrodes is disposed
in the cavity.
Electric control circuitry is connected to the electrodes for controllably
providing AC electric
power thereto. The electric control circuitry comprises current sense
circuitry for providing a
current sense signal indicative of an electric power usage of the electrodes.
A microcontroller is
connected to the current sense circuitry, an AC electric power supply, and a
user interface. The
microcontroller determines supply of the AC electric power to the electrodes
in dependence upon
the current sense signal and the user input signal and provides a supply
control signal indicative
of the supply of the AC electric power to the electrodes to the AC electric
power supply.
The advantage of the present invention is that it provides an instant
electrode water heater that is
simple and compact.
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A further advantage of the present invention is that it provides an instant
electrode water heater
that provides hot water at a substantially high start-up speed and efficiency.
A further advantage of the present invention is to provide an instant
electrode water heater that
enables substantially accurate control of the hot water temperature.
A further advantage of the present invention is to provide an instant
electrode water heater that
enables simple replacement of the electrodes.
BRIEF DESCRIPTION OF THE DRAWINGS
A preferred embodiment of the present invention is described below with
reference to the
accompanying drawings, in which:
Figures la and lb are simplified block diagrams illustrating perspective front
views of an
instant electrode water heater according to a preferred embodiment of the
invention;
Figure lc is a simplified block diagram illustrating a perspective rear view
of the instant
electrode water heater according to a preferred embodiment of the invention;
Figure ld is a simplified block diagram illustrating a cross-sectional view of
the electrode
cartridge of the instant electrode water heater according to a preferred
embodiment of the
invention;
Figure le is a simplified block diagram illustrating a front view of an
electrode of the
instant electrode water heater according to a preferred embodiment of the
invention;
Figures lf to lh are simplified block diagram illustrating cross-sectional
views of details
of the instant electrode water heater according to a preferred embodiment of
the
invention;
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Figure li is a simplified block diagram illustrating a cross-sectional view of
the electrode
cartridge of the instant electrode water heater according to a preferred
embodiment of the
invention;
Figure lk is a simplified block diagram illustrating a cross-sectional view of
the housing
of the instant electrode water heater according to a preferred embodiment of
the
invention;
o Figures 11 and lm are simplified block diagrams illustrating a top
view and a side view of
a heat sink element of the instant electrode water heater according to a
preferred
embodiment of the invention;
Figures 2a and 2b are simplified block diagrams illustrating an electric
control circuitry of
the instant electrode water heater according to a preferred embodiment of the
invention;
Figures 2c to 2h are simplified block diagrams illustrating components of the
electric
control circuitry of the instant electrode water heater according to a
preferred embodiment
of the invention;
Figure 3a is a simplified block diagram illustrating a side view of an instant
electrode
water heater according to another preferred embodiment of the invention; and,
Figures 3b and 3c are simplified block diagrams illustrating perspective views
of a quick
connect mechanism of the instant electrode water heater according to the other
preferred
embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Unless defined otherwise, all technical and scientific terms used herein have
the same meaning as
commonly understood by one of ordinary skill in the art to which the invention
belongs.
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Although any methods and materials similar or equivalent to those described
herein can be used
in the practice or testing of the present invention, the preferred methods and
materials are now
described.
While the description of the preferred embodiments hereinbelow is with
reference to a wall
mounted instant electrode water heater for providing hot water to, for
example, a shower or tap, it
will become evident to those skilled in the art that the embodiments of the
invention are not
limited thereto, but are also adaptable for use in appliances such as, for
example, coffee makers,
dish washers, and washing machines.
Referring to Figures la to lm, an instant electrode water heater 100 according
to a preferred
embodiment of the invention is provided. The instant electrode water heater
100 comprises an
electrically non-conductive housing 102 forming a cavity 112 between water
inlet 150.1 and
water outlet 150.2. Preferably, the housing 102 is mounted to - or forms a
single unit with ¨ wall
mounting plate 106, which may be mounted to wall 10 in a conventional manner -
using, for
example, screw fasteners - after connecting water inlet port 126.1 and water
outlet port 126.2 to a
waterline and electrical port 128 to an electrical supply, as illustrated in
Figures la and lb. It is
noted that the electrical supply should be surge protected using a fuse or
circuit breaker.
Preferably, electrodes 130 are contained in electrode cartridge 114 with the
same being
removably disposed in the cavity 112. Cover 104 is removably mounted to the
housing 102 -
using, for example, conventional easy to open/close fasteners such as spring
latches or magnetic
latches 108 - for covering the cavity 112 with the electrode cartridge 114
disposed therein in a
water sealed fashion using for example, an 0-ring seal 120 interacting with a
respective sealing
surface 122. The electrode cartridge 114, for example, comprises a cartridge
housing having a
bottom wall and sidewalls which, in concert with the cover 104, substantially
completely enclose
the electrodes 130. Inlet opening 116.1 and outlet opening 116.2 disposed in
the sidewalls such
that they align with the respective water inlet 150.1 and water outlet 150.2
of the cavity 112
when the electrode cartridge 114 is properly disposed therein, as illustrated
in Figures lb and ld.
The substantially complete enclosure of the electrodes 130 in the housing of
the electrode
cartridge 114 protects the electrodes during handling of the electrode
cartridge 114 by a user
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when removed from a protective packaging and inserted into the cavity 112, as
well as facilitates
the proper insertion of the same. Handling and insertion of the electrode
cartridge 114 is further
facilitated by providing the electrode cartridge 114 and the cover 104 as a
single unit.
AC electric power is provided to the electrodes 130 via electric cover
connector elements 118
disposed in the cover 104 such as, for example, banana plugs or pin plugs,
disposed in the cover
104 which are removably mated with respective electric housing connector
elements 162 such as,
for example, banana jacks or pin jacks disposed in the housing 102 and
connected to electric
control circuitry 170 disposed in control housing 124 mounted, for example, to
the wall
o mounting plate 106, as illustrated in Figures lb, ld, li, and lk. The
electric control circuitry 170
receives AC electric power from electrical port 128 connected to an electrical
supply and
controllably provides AC electric power to the electrodes 130. Preferably, the
electric control
circuitry 170 comprises current sense circuitry for providing a current sense
signal indicative of
an electric power usage of the electrodes 130 and a microcontroller connected
to the current
sense circuitry and user interface 110 such as, for example, a dial or touch
screen enabling the
user to set a desire hot water temperature. The microcontroller then
determines the supply of the
AC electric power to the electrodes 130 in dependence upon the current sense
signal and the user
input signal received from the user interface 110. A preferred embodiment of
the electric control
circuitry 170 will be described hereinbelow.
Preferably, a cover sensor 164 such as, for example, a Hall Effect sensor is
disposed in the
housing 102 for providing a cover sensor signal indicating if the cover 104
or, preferably, the
spring latch is opened or closed to the microcontroller, as illustrated in
Figure lk. If the cover
sensor signal is indicative of the cover/latch being opened, the
microcontroller stops provision of
the AC electrical power to the electric housing connector elements 162 until
the cover sensor
signal is indicative of the cover/latch being closed in order to protect the
user from electric shock
when replacing the electrode cartridge 114. Optionally, a solenoid valve 154
connected to the
electric control circuitry 170 is disposed between the water inlet port 126.1
and the water inlet
150.1. If the cover sensor signal is indicative of the cover/latch being
opened, the microcontroller
provides a signal to the solenoid valve 154 to shut off the water flow to the
water inlet 150.1
until the cover sensor signal is indicative of the cover/latch being closed in
order to enable the
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user to replace the electrode cartridge 114 without shutting off the water
supply. Further
optionally, the solenoid valve 154 is used to control the water flow to the
water inlet 150.1, for
example, to reduce the same when a desired hot water temperature cannot be
achieved.
Optionally, the electric control circuitry 170 is adapted for sensing a
resistance of the electrodes
130 and for providing a message, for example, displayed on user interface 110
when the sensed
resistance is indicative of a need for replacing the electrode cartridge 114.
Further optionally, the electrode cartridge 114 is one of a set of different
electrode cartridges 114
o with the electrodes 130 thereof being adapted for heating water having
different conductivity. For
example, the electrodes 130 are adapted to different water conductivities by
changing the
distance DE between the electrodes 130 and/or the size ¨ length LE and width
WE ¨ of the
electrodes 130, as well as the number of the electrodes 130. With the electric
control circuitry
170 being adapted for providing AC electric power to the electrodes 130 of any
one of the set of
different electrode cartridges 114, the instant electrode water heater 100 is
easily adapted for
heating water having specific water conductivity, enabling high speed and
efficiency. For
example, a user provides a water sample for testing the conductivity to
his/her retailer of the
water heater and can then purchase the appropriate electrode cartridge 114 in
dependence upon
the test result. This can be done prior purchasing the instant electrode water
heater 100, as well as
during the lifetime of thereof, for example, when purchasing a replacement
electrode cartridge
114 in order to adapt to changes in the water conductivity.
Preferably, the electrodes 130 are provided as a plurality of electrode plates
130 - having a
predetermined length LE, width WE , and thickness TE - disposed inside the
electrode cartridge
114, as illustrated in Figures ld and le. The electrode plates 130 are placed
such that they are
oriented parallel to each other having a predetermined distance DE between two
successive
electrode plates 130 for directing water received at the water inlet opening
116.1 through
successive channels with each channel formed by two successive electrode
plates 130 to the
water outlet opening 116.2 with the water being directed to flow in opposite
direction in any two
successive channels, as indicated by the block arrows in Figure ld. For
example, each electrode
plate 130 comprises an aperture 132 - such as, for example, a circular
aperture having a
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predetermined diameter DA - disposed in one end portion thereof for enabling
the water to flow
therethrough and wherein the apertures 132 are disposed in opposite end
portions of any two
successive electrode plates 130. Alternatively, the apertures 132 are replaced
by cut-outs in the
end portions of the electrode plates 130 or channels disposed in the cartridge
housing.
The electrode plates 130 are secured to the electrode cartridge 114 such that
the electrode plates
130 are enabled to vibrate in substantially all directions during provision of
the AC electric
power, which is achieved, for example, by accommodating the electrode plates
130 in respective
grooves 134 disposed in the bottom and/or sidewalls of the electrode cartridge
114, with the
grooves having a predetermined width WG which is greater than the thickness TE
of the
respective electrode plates 130 and a predetermined depth DG which is
sufficient for securing the
respective electrode plates 130 while vibrating, as illustrated in Figure lf.
The AC electric power
is provided to each of the electrode plates 130 using respective electric
contacts disposed in the
housing such that each electric contact is in a touching relationship with a
respective electrode
plate 130. The electric contacts are provided, for example, as pins 140 in
contact with the upper
end of the electrode plate 130 with a compression spring 142 interposed
between electric contact
plate 144 disposed in the cover 104 and the pin 140 to ensure electric contact
while also enabling
the electrode plate 130 to vibrate, as illustrated in Figure lg.
Alternatively, the electric contacts
are provided using spring clips 148 mounted to the cover 104, as illustrated
in Figure lh.
Further alternatively, the electric contacts are disposed in the bottom with
the electrode plates
130 placed thereupon and touching contact being ensured by placing a flexible
material such as,
for example, a foam insert between the top of the electrode plates 130 and the
cover 104.
The electric contacts are connected to a neutral wire 146.1 and a live wire
146.2 in
communication with the neutral electric cover connector element 118.1 and the
live electric
cover connector element 118.2, respectively, such that the electrode plates
130 are connected to
neutral AC and live AC in an alternating fashion, as illustrated in Figure li.
The housing 102, the cover 104, and the housing of the electrode cartridge 114
are made of a heat
resistant and electrically non-conductive material, preferably, a plastic
material such as, for
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example, Acetal using standard plastic molding techniques. Preferably, the
electrode plates 130
are made of graphite, manufacturing and installation of which is facilitated
by the simple shape
of the electrode plates 130 and the touching contact for provision of the
electric power.
Alternatively, the electrode plates 130 are made of another electrically
conductive material such
as, for example, aluminum, stainless steel, or brass. Further alternatively,
the electrode plates 130
have a different shape such as, for example, a circular shape to conform with
a cylindrical
housing.
The electrode plates 130 as described hereinabove provide a relatively large
amount of electric
power ¨ large electrode surface area in contact with the water - to a
relatively small amount of
water ¨ small channels between the electrode plates 130 ¨ compared to
conventional instant
electric water heaters, enabling a substantially compact instant electric
water heater having a
substantially high start-up speed and efficiency.
In an example implementation, 10 electrode plates 130 having length LE = 57mm,
width WE =
51mm, and spaced at distance DE = 1.5mm are employed to heat 4.51/min of water
by 40 C
using 240V at 40-45A supply power.
Optionally, the electrode cartridge 114 is omitted and the electrode plates
130 are directly
disposed in the housing 102.
It is noted that the cartridge assembly may also be implemented with other
shapes, arrangements
of the electrodes, as well as connecting mechanisms for providing the electric
power thereto.
Further optionally, the electric control circuitry 170 disposed, for example,
on a Printed Circuit
Board (PCB), is cooled using a heatsink element 166 in thermal contact with
the PCB, as
illustrated in figures 11 and lm. The heatsink element 166 comprises a block
made of a thermally
conductive material such as, for example, copper, having channels 168.1 and
168.3 disposed
therein for transmitting water therethrough. The channel 168.1 is connected to
the channel 168.3
via conduit 168.2 forming a loop which is connected to the water inlet in
order to use the cold
inlet water prior provision to the water inlet 150.1. A layer 172 of thermally
conducting but
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electrically insulating material is interposed between the heatsink element
166 and the electric
control circuitry 170. The layer 172 may be omitted if the PCB is a surface-
mount type PCB or
the heatsink element 166 is made of an electrically insulating material.
Referring to Figures 2a to 2h, an electric control circuitry 170 for
controlling the instant electrode
water heater 100 according to a preferred embodiment of the invention is
provided. The electric
control circuitry 170 comprises current sense and power supply circuitry 170A,
connected to the
electrodes 130 via in/port 174 and supply power via supply port 176 in
communication with
electrical port 128. The current sense and power supply circuitry 170A
provides a current sense
signal indicative of an electric power usage of the electrodes 130 and a
microcontroller 170B
connected to the current sense circuitry and user interface 110 such as, for
example, a dial or
touch screen via port 178, enabling the user to set a desire hot water
temperature. The
microcontroller then controls the supply of the AC electric power to the
electrodes 130 in
dependence upon the current sense signal and the user input signal received
from the user
interface 110.
The current sense and power supply circuitry 170A preferably comprises to
following
components, as illustrated in Figures 2b to 2h:
= Rectifier 170A.2 transforms AC voltage into rectified DC voltage;
= Current sensor 170A.3 uses a low resistance resistor to drop some voltage
off the rectified
DC voltage dependent on the power usage of the electrodes 130 and provides two
differential voltages having a difference proportional to the electrical power
usage of the
electrodes 130;
= H-Bridge 170.4 uses a network of 4 Insulated-Gate Bipolar Transistors
(IGBTs) to invert
the input rectified DC voltage from the current sensor into a custom AC
voltage
waveform dependent on the programming of the microcontroller 170B;
= Gate driver 170A.5 drives the gates of the IGBTs in the H-Bridge 170A.4
dependent on a
digital Pulse-Width Modulation (PWM) signal from the microcontroller 170B;
= Current sense amplifier 170A.6 takes the two differential voltages from
the current sensor
170A.3 and amplifies the difference which is measured by the microcontroller
170B; and,
= Power supply 170A.1 takes the AC supply voltage and provides 12V and 3.3V
output
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voltages to run the circuitry.
Microcontroller 170B drives the gate driver 170A.5 and reads the voltage
output from the current
sense amplifier 170A.6 and regulates the power provided to the electrodes 130
based on the
voltage output from the current sense amplifier to achieve a set power based
on the user input
signal or preprogrammed into the microcontroller 170B. The microcontroller is,
for example, a
suitable off-the-shelf Field-Programmable Gate Array (FPGA) as well as the
other components
are also off-the-shelf components assembled on a PCB using standard
technology.
Optionally, the microcontroller 170B is connected to: the cover sensor 164 via
port 180; the
solenoid valve 154 via port 182; inlet water temperature sensor 156 via port
184; outlet water
temperature sensor 158 via port 186; water flow sensor 160 via port 188; and,
water conductivity
sensor 161 via port 190.
For example, the microcontroller 170B receives a cover sensor signal
indicating if the cover 104
or the spring latch 108 is opened or closed to the microcontroller 170B. If
the cover sensor signal
is indicative of the cover/latch being opened, the microcontroller 170B stops
provision of the AC
electrical power to the electric housing connector elements 162 until the
cover sensor signal is
indicative of the cover/latch being closed in order to protect the user from
electric shock when
replacing the electrode cartridge 114. The microcontroller 170B may also send
a signal to the
solenoid valve 154 to shut off the water flow if the cover sensor signal is
indicative of the
cover/latch being opened. Furthermore, the microcontroller 170B may receive
one or more
signals indicative of the inlet water temperature, the outlet water
temperature, the water flow rate,
and the water conductivity in order to, for example: determine the start/stop
and the amount of
electrical power provide to the electrodes 130 based thereon in addition to
the current sense
signal to achieve a set hot water temperature; determine if the electrodes 130
need to be replaced
and provide a message to the user interface 110 indicative thereof; determine
one of the set of
different electrode cartridges 114 in dependence upon the provided electrical
power and provide
a message to the user interface 110 indicative thereof; adjust the provision
of electrical power to
the electrodes 130 to changes in the water conductivity or to shut off the
electrical power if the
changes are greater than a predetermined threshold; adjust the provision of
electrical power to
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changes in resistance of the electrodes 130; and, reduce the water flow if a
set hot water
temperature cannot be achieved.
As is evident to one skilled in the art, the electric control circuitry 170
may also be adapted for
controlling other designs of instant electrode water heaters than the instant
electrode water heater
100.
Alternatively, the current sense and power supply circuitry 170A described
hereinabove is
replaced by circuitry using a TRIode for Alternating Current (TRIAC) for
sensing the AC
o voltages and regulate the provision of electrical power to the electrodes
using Phase Controlled
Dimming. While the TRIAC based circuitry is somewhat simpler it is less
efficient, in particular,
if not water-cooled.
Referring to Figures 3a to 3c, an instant electrode water heater 200 according
to another preferred
embodiment of the invention is provided. Here, the instant electrode water
heater 200 comprises
a housing 202 having water inlet port 206A for receiving cold inlet water,
water outlet port 208A
for providing the heated water, and electrical port 204A. The water inlet port
206A comprises a
quick connector element for being easily mated with a respective wall
connector element 206B
and the electrical port 204A comprises a standard electrical plug for being
easily mated with a
respective wall outlet 204B. The water inlet port 206A and the electrical port
204A are place in
proximity to each other such they are simultaneously mated with their
respective counterparts
206B, 204B. Preferably, the wall connector element 206B comprises a shut off
mechanism for
shutting off the water flow when the water inlet port 206A is disconnected
therefrom. Further
preferably, the wall outlet 204B also comprises a shut off mechanism for
shutting off the electric
power supply when the electrical port 204A is disconnected therefrom.
It is noted that the instant electrode water heater 200 may be implemented
with the electrode
plates 130 and/or the cartridge assembly as well as with various other designs
of instant electrode
water heaters.
The present invention has been described herein with regard to preferred
embodiments. However,
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it will be obvious to persons skilled in the art that a number of variations
and modifications can
be made without departing from the scope of the invention as described herein.
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