Note: Descriptions are shown in the official language in which they were submitted.
CA 02582175 2007-03-23
CONTROL SYSTEM FOR BATHERS
TECHNICAL FIELD OF THE INVENTION
This invention relates to control systems for bathing
systems such as portable spas.
BACKGROUND OF THE INVENTION
A bathing system such as a spa typically includes
a vessel for holding water, pumps, a blower, a light,
a heater and a control for managing these features.
The control usually includes a control panel and a series
of switches which connect to the various components with
electrical wire. Sensors then detect water temperature and
water flow parameters, and feed this information into a
microprocessor which operates the pumps and heater in
accordance with programming. U.S. Patent Nos. 5,361,215,
5,559,720 and 5,550,753 show various methods of
implementing a microprocessor based spa control system.
For a properly designed system, the safety of the user
and the equipment is important, and is typically concerned
with the elimination of shock hazard through effective
insulation and isolated circuity, which prevents normal
supply voltage from reaching the user. Examples of
isolation systems for spa side electronic control panels
are described in U.S. Patent Nos. 4,618,797 and 5,332,944.
SUMMARY OF THE INVENTION
Accordingly, in one aspect of the present invention
there is provided a spa including a heating and control
system for bathers, comprising:
a control circuit board assembly;
a high voltage power supply connected to the control
circuit board assembly;
a heater assembly connected to the control circuit
board assembly;
CA 02582175 2007-03-23
2
water presence sensor apparatus to determine the
presence of water within the heater assembly;
a pump for circulating water through said heater
assembly;
at least one temperature sensor for generating an
electrical signal proportional to water temperature located
at said heater; and
an electronic controller adapted to selectively activate
and deactivate said pump at selected time intervals.
According to another aspect of the present invention
there is provided a heating and control system for bathers,
comprising:
an electronic controller;
an electric heater assembly connected in a water flow
path for heating water passing therethrough, the controller
arranged to control the operation of the heater element,
the heater assembly including a water conduit having a
first port and a second port;
water temperature sensor apparatus providing
electrical temperature signals to the controller indicative
of water temperature at separated first and second
locations on or within said heater assembly or a
combination thereof; and
solid state water presence sensor apparatus to
determine the presence or absence of water within said
heater assembly, and to provide electrical water presence
signals to the controller indicative of the presence or
absence of a body of water within the heater assembly, said
water presence sensor free of any moving parts in the flow
path; the controller responsive to signals from the water
temperature sensor apparatus and the electrical water
presence signals to control the heater assembly, said
controller responsive to said electrical water presence
signals indicating the absence of a body of water to
disable operation of the heater assembly;
wherein the heater assembly may be connected in the
water path in a first orientation with the water entering
CA 02582175 2007-03-23
3
the first port and exiting the second port, or in a second
orientation with water entering the second port and exiting
the first port, with the water presence sensor operational
with the heater assembly in the first orientation and with
the heater assembly in the second orientation.
According to yet another aspect of the present
invention there is provided a spa system for bathers,
comprising:
a vessel for holding a body of water;
a water heater assembly having a first input/output
port and a second input/output port, the assembly connected
in a water recirculation path coupled to the vessel;
water presence sensor apparatus to determine the
presence of water within the heater assembly and provide
water presence signals indicative of the presence or
absence of a body of water within the heater assembly;
a pump having an inlet port and an outlet port
connected in the water recirculation path for recirculating
water through said heater assembly and said vessel;
water temperature sensor apparatus providing
electrical temperature signals indicative of water
temperature at separated first and second locations on or
within said heater assembly, the sensor apparatus free of
any moving parts within the water recirculation path;
the water heater assembly configured for connection in
the water recirculation path either upstream of the pump
inlet port or downstream of the pump outlet port, and with
either the first input/output port or the second
input/output port connected in the water recirculation path
as the water heater inlet; and
an electronic controller for selectively activating
and deactivating said pump at selected time intervals, said
controller responsive to said temperature signals and said
water presence signal to manage water parameters.
According to still yet another aspect of the present
invention there is a method of controlling a spa system
including a tub holding a body of spa water, a water
CA 02582175 2007-03-23
4
circulation system for recirculating spa water through a
water heater to heat the spa water, the system including a
user control panel operatively connected to a control
system for entering manual commands to control spa
parameters, the method comprising:
operating the spa system in a standard spa mode at a
spa water temperature use setting or at a water temperature
set by manual command entered by a user or a preset
temperature;
monitoring non-usage of the spa system by the user;
and
automatically setting the spa system to a low energy
usage mode a predetermined time period after use of the spa
has ceased.
BRIEF DESCRIPTION OF THE DRAWING
These and other features and advantages of the present
invention will become more apparent from the following
detailed description of an exemplary embodiment thereof,
as illustrated in the accompanying drawings, in which:
FIG. 1 is a schematic diagram of a system for bathers
including a vessel for holding bathing water, a control
system, and associated water management equipment.
FIG. 2A is a schematic block diagram of an embodiment
of a control for a bathing system with various safety and
water management features.
FIG. 2B is an isometric view of an exemplary
embodiment of the control circuit board assembly enclosure
and attached heater assembly.
FIG. 3 is an electrical schematic diagram showing one
embodiment of a water detection safety and water management
electrical circuits associated with a system for bathers.
FIG. 4 is an electrical schematic diagram of one
embodiment of a ground fault circuit interrupter circuit
integrated into a system for bathers.
CA 02582175 2007-03-23
FIG. 5 shows a Ground Integrity Detector circuit to
detect and identify a disconnected ground.
FIG. 6 is a schematic diagram of a Ground Current
Detector circuit to identify and detect when current is
5 flowing through the earth grounding circuit of the spa
wiring.
FIG. 7A is a cross-sectional diagram of a temperature
sensor assembly showing the conductive casing and the
components therein.
FIG. 7B is a simplified flow diagram illustrating a
technique for detecting the presence of water in the heater
housing.
FIG. 8 illustrates a partial program structure showing
relevant relationship of a main program block.
FIG. 9 is a flow diagram illustrative of a panel
service program which responds to button activation to
change operational modes of the spa.
FIGS. 10A-lOB represent a flow diagram illustrating
the operation of a safety circuit, temperature measurement
and water detection method.
FIG. 11 is a flow diagram illustrating a technique for
self calibration of temperature sensors and display of
error message.
FIGS. 12A-12B represent a flow diagram illustrative of
a program to monitor a safety circuit, temperature rate of
rise, GFCI and temperature sensor short/open detection.
FIGS. 13A-13B represent a flow diagram of a standard
mode of operation of a program for intelligent, temperature
maintenance using rate of heat loss to drive sampling
frequency schedule.
FIG. 14 is a flow diagram of an economy mode of
operation of a program for temperature management.
FIG. 15 is a flow diagram of a standby mode of
operation of a program for temperature management.
CA 02582175 2007-03-23
6
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 illustrates an overall block diagram of a spa
system with typical equipment and plumbing installed. The
system includes a spa 1 for bathers with water, and a
control system 2 to activate and manage the various
parameters of the spa. Connected to the spa 1 through a
series of plumbing lines 13 are pumps 4 and 5 for pumping
water, a skimmer 12 for cleaning the surface of the spa,
a filter 20 for removing particulate impurities in the
water, an air blower 6 for delivering therapy bubbles to
the spa through air pipe 19, and an electric heater 3 for
maintaining the temperature of the spa at a temperature
set by the user. The heater 3 in this embodiment is an
electric heater, but a gas heater can be used for this
purpose also. Generally, a light 7 is provided for
internal illumination of the water.
Service voltage power is supplied to the spa control
system at electrical service wiring 15, which can be 120V
or 240V single phase 60 cycle, 220V single phase 50 cycle,
or any other generally accepted power service suitable for
commercial or residential service. An earth ground 16 is
connected to the control system and there through to all
electrical components which carry service voltage power and
all metal parts. Electrically connected to the control
system through respective cables 9 and 11 are the control
panels 8 and 10. All components powered by the control
system are connected by cables 14 suitable for carrying
appropriate levels of voltage and current to properly
operate the spa.
Water is drawn to the plumbing system generally
through the skimmer 12 or suction fittings 17, and
discharged back into the spa through therapy jets 18.
An exemplary embodiment of the electronic control
system is illustrated in schematic form in FIG. 2A. The
control system circuit assembly board is housed in a
protective metallic enclosure 200, as illustrated in FIG.
CA 02582175 2007-03-23
7
2B. The heater assembly 3 is attached to the enclosure
200, and includes inlet/outlet ports 3A, 3B with couplings
for connection to the spa water pipe system.
As shown in FIG. 2A, the electronic control system 2
includes a variety of electrical components generally
disposed on a circuit board 23 and connected to the service
voltage power connection 15. Earth ground 16 is brought
within the enclosure 200 of the electronic control system
and is attached to a common collection point.
Adjacent to the circuit board 23 and connected via an
electrical plug, a power and isolation transformer 24 is
provided. This transformer converts the service line power
from high voltage with respect to earth ground to low
voltage, fully isolated from the service line power by a
variety of methods well known in the art.
Also provided on the circuit board 23, in this
exemplary embodiment, is a control system computer 35, e.g.
a microcomputer such as a Pic 16C65A CMOS microcomputer
marketed by Microchip, which accepts information from a
variety of sensors and acts on the information, thereby
operating according to instructions described more fully in
FIG. 14. The invention is not limited to the use of a
controller including a microcomputer or microprocessor,
whose functions can instead be performed by other
circuitry, including, by way of example only, an ASIC, or
by discrete logic circuitry.
One output of the computer 35 is displayed on the
control panel 8 through a character display system rendered
optically visible by technology generally known in the art.
Tactile sensors 22 are provided to convert user
instructions to computer readable format which is returned
to the control system computer 35 via cable 9.
The equipment necessary to heat and manage the water
quality, i.e. the heater system 3, pumps 5 and 6, blower 4
and light 7, are connected via electrical cables 14 to
relays 36, 126, 129 and 130 on the circuit board 23, which
function under the control of relay drivers 34, selectively
CA 02582175 2007-03-23
8
driven by the microcomputer 35. These relays and relay
drivers function as electrically controlled switches to
operate the powered devices, and are accomplished by
methods well known in the art and provide electrical
isolation from the service voltage power for the low
voltage control circuitry. Of course, other types of
switching devices can alternatively be employed, such as
SCRs and triacs.
Referring now to FIG. 3, also arrayed upon the circuit
board and integral thereto in this exemplary embodiment are
several safety circuits, which protect the system in case
of error or failure of the components. Shown in the
functional schematic diagram of FIG. 3 is the heater system
3, which includes a generally tubular metal housing 3A
constructed of a corrosion resistant material such as 316
stainless steel, a heater element 42 for heating the water,
a heater power connection 37 from heater relays to the
terminal of the heater element, and sensors 31 and 32
connected through lines 40 to appropriate circuity on the
circuit board. These sensors are connected on the circuit
board to both a hardware high limit circuit 33 (FIG. 2A)
and to the computer control circuit 35.
A torroid 30, constructed in accordance with
techniques well known in the art, is provided through which
the earth ground connection 16 from the heater housing and
any other ground connection in the system passes. This
torroid is electrically connected by cable 41 to the ground
current detector circuitry 29 which is more fully described
in FIG. 6. The output of the ground current detector (GCD)
is provided to the computer system 35 via an electrical
connection through the signal conditioning circuitry.
The service voltage power is provided to the system
through the center of a pair of conventional torroids 25
and 26. The electrical outputs of these torroids are
connected to a ground fault circuit interrupter circuit 27
by electrical connections shown as 38 and 39. The ground
fault circuit interrupter is described more fully in
CA 02582175 2007-03-23
9
FIG. 4. The ground fault circuit interrupter feeds a
signal to the computer 35, which tells the computer of a
ground fault existence. Testing of the ground fault
circuit interrupter is managed by the computer on a regular
basis, and an exemplary program algorithm of this activity
is illustrated in FIG. 11.
A ground integrity detector 28 is provided which is
more fully described in FIG. 5. The ground integrity
detector is attached to the earth ground 16 and provides a
signal to the computer control 35. If more than one earth
ground is used in a particular application, another ground
integrity detector could be used in accordance with the
invention to verify the ground continuity.
FIG. 3 is a schematic diagram of a temperature sensing
system for a spa, and comprises the control system. Heater
assembly 3 has a heater shell 3A, most usually made of
metal, but can also be constructed of conductive plastic or
of plastic with an internal metallic ground plate.
Confined within the heater shell is a heater element 43,
constructed to provide insulation from the water as
generally known in the art. Power is provided to the
heater element from connection points 124 and 127.
This power is provided responsively to the programmed
temperature provided to the microcomputer 35 through
control panel 22 as is generally known from the prior art.
In this exemplary embodiment, the heater housing 50 is
tubular in shape. However, other shapes come within the
scope of this invention provided they have an inlet and an
outlet. Located close to each end of the heater element
are temperature sensor assemblies. These assemblies
include thermistors 133 and 134, which are usually of a
negative temperature coefficient (d). However, they can be
positive temperature coefficient thermistors, thermocouples
or any other temperature sensitive means. The temperature
sensor is generally potted in epoxy or the like, in
stainless steel housings 31 and 32. The stainless steel
housings are mounted into the side of the heater assembly
CA 02582175 2007-03-23
with insulating collars, which provides a water pressure
seal and an insulative barrier from the heater housing.
However, when water is present, there is a conductive
path which can be detected by the associated circuitry.
5 This conductive path extends from sensor housing 32 to
sensor housing 31 through the water in the housing.
When microcomputer 35 sets the output high through resistor
pair 78, 79, current travels through connecting wires 141,
143 and the sensor housings 31A, 32A, water between the
10 sensor housings, and voltage divider network created by
resistor pair 80, 81, resistor 84, resistor pair 82, 83 and
resistor 91. The resulting voltage is buffered to the
microcomputer by op amp 90, which is powered and installed
according to known techniques.
FIG. 7A illustrates in cross-section an exemplary one
of the temperature sensor assemblies 31, 33. The assembly
31 includes a stainless steel or other corrosion-resistant
housing 31A, which is mounted into the heater housing using
an insulative bushing 31B. The bushing is fabricated of a
dielectric material, for example, KYNAR (TM) or
polyprophylene, thus electrically insulating the housing
31A from the heater housing. The bushing 31B can have a
threaded peripheral surface (as shown) which is threaded
into a correspondingly threaded opening in the heater
housing. Alternatively or in addition, the bushing can be
sealed into the opening with a non-conductive adhesive.
The thermistor 133 is mounted at a distal end of the
housing 31A, to be positioned within the heater housing in
close proximity to the water flow through the heater
housing. Wires 144 provide an electrical connection to the
thermistor from the circuit 2. A third wire 143 is passed
into the housing 31A from circuit 2, and is electrically
connected to the housing 31A, e.g. by a solder connection.
This connection (wire 143) is used in the water presence
detection process. The elements 133 and 143-144 are potted
with a potting compound such as epoxy.
CA 02582175 2007-03-23
11
In operation previously described, the water detection
system is normally held in a low state by the microcomputer
output, which is turned off. When the microcomputer
program turns the output on, or switches to a high state,
if no water is present to form a conductive path, no change
is detected at the output of op amp 90. However, if water
is present, then the output of 90 changes state in
response to state change of the output because of the
conductive characteristic of water under electrical
current. This circuit is activated for very short periods
of time and then returned to an inactive or grounded state.
An exemplary effective cycle could be for 5 milliseconds
every 100 milliseconds. In addition, it may be advisable
to change polarity on each sensor to prevent corrosion
damaging one sensor to the point of destruction.
FIGS. 3 and 7A thus illustrate a combination sensor
which uses the housing of the temperature sensor for the
water presence detector. A separate pair of electrodes
distinct from the temperature sensor is also within the
scope of this invention, as is the concept of using the
shell of the heater housing for one electrode, and an
insulated, conductive probe, both hooked to a resistor
divider network, as previously described.
Since the water presence detector has no moving parts,
water may enter the heater housing from either end and flow
out the other end. Generally, a pump has an inlet, or
suction side, and an outlet, or pressure side. The heater
assembly fitted with the water presence detector may
therefore be fitted to either the suction or outlet side
of the pump with equally satisfactory results. This
flexibility is extremely valuable, as it allows exceptional
latitude in the principal layout configuration of the pump
and heater components for assembly into the spa.
Temperature information regarding the heater is gained
through sensor thermistors 134 and 133, formed and placed
generally adjacent to the heater element, and on either end
of the heater element. As the thermistors change
CA 02582175 2007-03-23
12
resistance in response to the immediate temperature
surrounding, an electrical signal is generated at the
output of op amps 97 and 89, through associated electrical
circuitry. Resistors 88, 85 and capacitors 87 and 86 are
configured to provide the current form of electrical
input to provide a sensible voltage through the op amp.
Each temperature sensor is configured in like manner.
When water is flowing in the heater assembly, both
temperature sensors will reach equilibrium and provide a
proportionally equal voltage if the heater element 42 is
not activated.
Under control of the microcomputer, if the heater
element is energized, the physical location of the
temperature sensors may then detect a different temperature
of water between the inlet and the outlet of the heater
housing. Depending on the actual set temperature of the
controller, the microcomputer will elect to use the
temperature of the lower, or inlet side sensor, as the
actual temperature of the spa, and turn off the heater when
the temperature of the spa is equal to the desired
temperature of the spa.
If the water flow slows down to a point where there is
a substantial difference between the inlet and outlet
temperature, then the microcomputer can interpret this as a
trouble signal and deactivate the heater. Further, if
there is a blockage in the plumbing, or the pump fails to
circulate water, the temperature in the heater housing may
rise to unacceptable limits. Accordingly, op amps 105 and
104, not feeding into the microcomputer, but entirely
independent circuit have a reference network of resistors
which provides a precision reference voltage. When the
input to either of the op amps 104, 105 exceeds the
precision reference voltage, the output of the op amp
swings appropriately to deactivate transistor 133 thereby
causing gate 118 to change state, and causing relay driver
131 to turn off heater relays 130 and 129. The heater is
therefore shut off and can only be reactivated by a
CA 02582175 2007-03-23
13
manual reset signal from control panel 22, through the
microcomputer, which changes state of gate 118. However,
as long as either temperature sensor remains above a
temperature set by the reference voltage networks, the
manual reset signal cannot work. An exemplary appropriate
temperature for the high limit circuit deactivation is
between 118 F and 122 F to protect from injury. As long as
a manual reset signal is not given, the circuit will remain
in an off state.
Each described circuit is sensibly connected to the
microcomputer 35, which has electrical inputs responsive to
changes in voltage level from a logic high to a logic low.
An exemplary embodiment employs a relatively sophisticated
microcomputer, and 8 bit microcomputers and more powerful
microcomputers can be employed. Typically an embodiment of
this invention would employ a CMOS or complimentary metal
oxide version of a microcomputer.
Because the temperature sensors 31 and 32 generate a
voltage proportional to temperature, a device such as an
analog to digital converter 99 is used to convert the
analog voltage to a readily usable digital value which
is provided at the microcomputer via customary means.
In a preferred embodiment, the temperature measurement
components are thermistors which are matched in their
resistance versus temperature values. Typically,
accuracies are available of .2 C precision, meaning two
thermistors held at a precise resistance value by varying
the temperature of each independently will match within .2 C
of an equal temperature. By using thermistors of no more
than 1 C precision, the system will not require calibration
of the hardware interface of the electrical signal of the
thermistor temperature output. In addition, if the
computer is able to circulate water through the system
without activating the heater, the temperature sensors will
be in the same temperature environment. Therefore, the
computer will able to compare the readings of the sensors
CA 02582175 2007-03-23
14
to determine if they are within the precision specified
above, 1 C, and provide a software calibration for final
correction.
An additional or alternative technique for sensing the
presence of water in the heater housing is illustrated in
the flow diagram of FIG. 7B. This embodiment senses the
water flow, which will tend to cool the heater and
temperature sensor assemblies. In the absence of water or
water flow, with the heater energized, the temperature
sensors will detect a significantly increased rate of
temperature rise. This can then be used to determine that
no water is present or that components have failed (e.g.,
water pump failure). While the water pump 1 is activated,
the microprocessor 35 may activate the heater 3 for a
selected period of time, say 4 seconds, deactivate the
heater for a selected period of time, say one minute, and
compare the temperature readings before the activation
began to the readings after the selected off time interval.
If the temperature difference exceeds a predetermined
amount, say 10 degrees, then the heater can be determined
by the microprocessor to have no water present in the
housing. This technique is illustrated in FIG. 7B with a
an operational subroutine executed by the microprocessor.
The water pump is activated during the steps 350-356.
At step 350, a first temperature reading at both of the
temperature sensors is taken with the heater off. Then,
the heater is turned on for a predetermined time interval
(step 353) and then turned off. After another time
interval has elapsed (step 354), a second temperature
reading is taken (step 356). The difference between the
two readings for each temperature sensor is then taken, and
compared to a threshold (step 358). If the difference for
either sensor is greater than this threshold, then the
microprocessor declares that no water is present or that
there is a component failure (step 360). If the difference
is not greater than the threshold, the microprocessor
determines (step 362) whether any other faults have been
CA 02582175 2007-03-23
detected, such as too large a differential between the
temperature readings taken at the two sensors 31, 33
(described more fully below). If so, the operation
branches to step 360. Otherwise, the microprocessor will
5 determine that water is present in the heater housing
(step 364).
Shown in FIG. 4 is a Ground Fault Circuit Interrupter
(GFCI) circuit. This electrical circuit is configured to
be in close relationship with the electrical system which
10 controls the spa equipment. The main power supply which
supplies the current to the spa equipment and control is
shown at 15, and passes through two torroids, shown at 25
and 26. As long as the net current flowing through the
torroids is equal, the torroids see a no magnetic flux.
15 However, if a device, such as a heater element fails, some
current escapes through the earth ground, as at 16.
When an imbalance occurs, an electromagnetic coupling
occurs which sets up an electrical current in the sense
circuit 150 associated with the detection torroids. The
circuit 150 outputs a fault or error signal proportional
to current flow which is provided to the microcomputer
(via analog-to-digital conversion, not shown in FIG. 4).
The microcomputer then responds with an error message which
is displayed on the control panel 22. In addition, a fault
creates a change in state at output connection 116, which
connects to 117 on FIG. 3. This connection activates
the circuits generally beginning at diode 109. This in
turn triggers transistor 133. Gate 118 changes state in
response, deactivating relay driver 131 and opening relays
129 and 130d. Microcomputer 35 also opens all other
relays, 36, disconnecting any other components, such as
pumps, blowers and lights.
Microcomputer 35 can test the functionality of the
GFCI circuit by outputting a signal through resistor 56,
which activates transistor 54, closing relay 52. Current
passes through resistor 23, bypassing torroids 25 and 26,
imbalancing the current flowing through the torroids. This
CA 02582175 2007-03-23
16
causes GFCI circuitry to trigger, providing a signal to
microcomputer 35 that the circuit has properly triggered.
When the microcomputer senses a trigger signal, it resets
test relay 52 by restoring status to resistor 56. Because
a GFCI fault triggers the high limit relays 129 and 130,
opening them up, the microcomputer also generates a system
reset signal on line 198 which re-enables the drivers which
activate the relays 129 and 130. This sequence of events
is carried on periodically, such as once per day, to verify
the functionality of the GFCI circuit. Generally, a real
time clock, functioning as a master timekeeper, would
provide a reference signal and a programmed interval
between tests, such as 24 hours could be set using
techniques known by ones skilled in the art of
microcomputer programming.
FIG. 5 illustrates a Ground Integrity Detector (GID)
device. The Ground Integrity Detector includes a neon bulb
connected in series with a limiting resistor 43 from
the power service voltage to the system earth ground 16.
20 If the ground is properly connected, current will flow from
the supply, through the limiting resistor. The current
flow can be limited to less than one milliampere (ma).
The light from the neon bulb is contained in a light tight
enclosure 28, which also contains an opto-resistive
device which falls in resistance in the presence of light.
By connecting this opto-resistive device in a resistor
divider circuit, shown generally at 46, a signal indicating
the presence of light and therefore of a good ground, can
be presented to the computer control system. The computer
control system then manages this information according to
instructions more fully described in FIG. 11.
Shown at FIG. 6 is a Ground Current Detector (GCD) .
The ground current detector is shown as capable of
detecting currents which might flow in a ground attached to
a heater current collector or shell 50 which is part of the
heater assembly 3, including a heater element 42, and any
CA 02582175 2007-03-23
17
other device powered or containing line voltage, such as
lights, blowers and pumps, and the enclosure itself.
As an example, in normal service, heater elements 42
may fail and rupture due to either mechanical failure,
corrosion, or electrical breakdown. The shell of the
heater 50 then collects the current and routes it through
the ground line, thereby protecting both the occupant of
the spa and the equipment. However, if the current is
allowed to flow indefinitely, there is a possibility of
health hazard or equipment damage occurring. when current
flows through the ground line 16, an electromagnetic
coupling occurs between the current and the torroid 30
through which it passes. This coupling creates a voltage
proportional to the current, and if the current is an AC
current, an AC voltage will be induced in the torroid.
When this voltage is provided to a full wave rectifier
comprising sense circuit 152, a rectified DC signal is
created. After conditioning this rectified DC signal with
a capacitor 48 and resistor 49, a DC signal is generated
proportional to current flow. (Alternatively, circuit 152
with its full wave rectifier can be replaced with a sense
circuit similar to circuit 150 (FIG. 4), producing an error
signal proportional to current flow.) When no current is
flowing, the bleed resistor 50 insulates the circuit from
the electrical noise. The computer control 35 consistently
monitors the state of the input signal line from the GCD
circuit. If a ground current is detected, the computer
responds in accordance with instructions more fully
explained in FIG. 11 to shut off the relays 36 through
relay drivers 34 to reduce hazards to equipment and
personnel.
Referring now to computer flow diagrams at FIGS. 8-13,
the functional interrelation of the various prior
described components is disclosed. These flow diagrams
illustrate the action which is directed by the computer 35,
as shown on FIG. 2A, responding to signals generated
from the control panel 22 through interconnect cable 9.
CA 02582175 2007-03-23
18
The microprocessor is programmed to accomplish the
functions illustrated therein.
As shown in FIG. 8 in block form, and more fully
disclosed in FIGS. 9-14, the spa control system computer is
constantly running a safety and error detection program.
At any time in this program, a control panel signal can
interrupt the program, branching off into the panel service
program. When the mode button is pressed, the program
branches into the "mode selection" routine, shown in
FIGS. 10A-10B. In the mode selection routine, one of three
modes is selected, standard, economy or standby. Once a
time interval has passed without further button presses,
typically 3 seconds, the program reverts back to the safety
program, looping through the proper "mode" program also.
When the control system is first energized, it is default
programmed to start in the economy (econ) mode.
To more fully describe the process diagrammed, the
steps are described below.
FIGS. 10A-lOB
Step 225. Starting point of the program for flow
chart purposes. Program normally initializes by known
means to clear and reset all registers upon power up.
Step 226. Check for presence of water in heater.
If none, branch to 227, otherwise branch to 228.
Step 227. Disable heater and loop back to 226.
Step 228. Check for software set high limit of 118 F.
If temperature at either temperature sensor exceeds this
value, the heater is turned off. If less than 118 F,
program loops to 232.
Step 229. Turn heater off.
Step 230. Display error message on control panel 8 of
OH2 to signify overheat - at least 118 F.
Step 231. Remeasure temperature sensor. If
temperature exceeds 116 F, program loops back to Step 229.
If less than 116 F, program loops to Step 228.
CA 02582175 2007-03-23
19
Step 232. Check for hardware high limit, if tripped
branch to 233, otherwise 237.
Step 233. Shut down system.
Step 234. Display error condition "OH3" for overheat
hardware high limit.
Step 235. Measure water temperature. If less than
116 F, then branch to 236, otherwise branch to 233.
Step 236. Check for control panel input. If any
button is pressed, system will reset.
Step 237. If water temperature is over 112 F, branch
to 238, otherwise go to 241.
Step 238. Turn off everything - branch to 239.
Step 239. Display system error message "OHl" for
overheat of at least 112 F.
Step 240. Remeasure water temperature, if less than
110 F, branch to 240, otherwise branch to 241.
Step 241. Check for balance between water temperature
sensors. If a difference of greater than 5 F exists, branch
to 242, otherwise branch to 244.
Step 242. Turn heater off. Branch to 243.
Step 243. Display error message HFL, meaning the
water flow in the heater is too low. Branch to 241.
Step 244. Proceed to 273.
FIG. 11
Step 273. If the heater is on, proceed to 274.
If not, proceed to 340.
Step 340. Measure output of temperature sensor 1.
Step 341. Measure output of temperature sensor 2.
Step 342. Subtract lowest value from highest value.
Step 343. If the result is less than or equal to 1 F,
then proceed to 345, otherwise proceed to 344.
Step 344. Send error message "CAL" to display on
control panel. Proceed to 274.
Step 345. Store result in lowest sensor value
register.
CA 02582175 2007-03-23
Step 346. Add contents of calibration register to all
temperature measurement operations. Proceed to 274.
FIGS. 12A-12B
5 Step 250. Has either sensor changed temperature more
than 2 F/second? If so, proceed to 251, otherwise proceed
to 253.
Step 251. Turn off heater, proceed to 252.
Step 252. Display "HTH1" error message for heater
10 imbalance. Proceed to 250.
Step 253. Check proper input for ground integrity,
that is, is the ground properly connected. If not, proceed
to 254, otherwise branch to 256.
Step 254. Turn off system, proceed to 255.
15 Step 255. Display error message GR for ground
disconnected or not properly hooked up. Proceed to 253.
Step 256. Check for ground leakage current. If none,
proceed to 245. If yes, branch to 257.
Step 245. Is GFCI tripped? No, branch to 259.
20 If yes, branch to 246.
Step 246. Shut down system and open all relays.
Proceed to 247.
Step 247. Display GFCI error message indicating there
is a ground circuit fault. Proceed to 248.
Step 248. Has system reset been pressed from control
panel? If yes, loop to 245, otherwise loop to 247.
Step 257. Turn everything off. Proceed to 258.
Step 258. Display GRL error message to indicate
ground leakage detected, proceed to 256.
Step 259. Check real time clock. If time is equal to
2:00 am, branch to 260, otherwise proceed to 266.
Step 260. Test ground fault interrupter circuit by
closing relay to imbalance current in power supply.
Step 261. Check for GFCI system trip. If yes,
proceed to 263, if no branch to 262.
Step 262. Turn off system, proceed to 265.
CA 02582175 2007-03-23
21
Step 265. Display error message GFCF for ground fault
interrupter circuit failure, proceed to 261.
Step 263. Reset GFCI circuit via microprocessor
reset, proceed to 264.
Step 264. Reset hi-limit circuit via microprocessor
output. Branch to 266.
Step 266. Is either temperature sensor disconnected?
If yes, 267. If no, 269.
Step 267. Turn everything off, proceed to 268.
Step 268. Display SND, loop to 266.
Step 269. Is either temperature sensor shorted?
If yes, proceed to 270. If no, 275.
Step 270. Turn off system, proceed to 271.
Step 271. Display error message SNS. Loop to 269.
Step 275. Proceed to mode as selected by panel
service program.
FIGS. 13A-13B
Step 276. Program checks for function of pump 1 which
circulates water through heater. If pump is already on,
program proceeds to 282, otherwise program proceeds to 277.
Step 277. Check for 30 minute elapsed time. If pump
has been off for less than 30 minutes, branch back to main
safety program at 225. If pump has been off for 30
minutes, proceed to 227.
Step 278. If water temperature has dropped more than
1 F below set temperature in the last hour, proceed to 281,
if not, proceed to 279.
Step 279. Reset iteration counter to zero and proceed
to 280.
Step 280. Reset 30 minute pump off timer and proceed
to 225 main safety program.
Step 281. Turn pump on, proceed to 282.
Step 282. Allow pump to run for 30 seconds. If not,
look back to main safety program 225. If so, proceed to
283.
Step 283. Read water temperature, proceed to 284.
CA 02582175 2007-03-23
22
Step 284. Check to see if 5 seconds has passed from
beginning of water temperature read. If so, proceed to
285, otherwise loop back to 283.
Step 285. Compare water temperature to set
temperature. If water temperature higher than set
temperature, proceed to 286. If not, proceed to 287.
Step 286. Increment iteration counter, proceed to
290.
Step 287. If water temperature is more than 1 F below
set temperature, proceed to 288, otherwise proceed to 286.
Step 288. Reset iteration counters. Proceed to 289.
Step 289. Turn on heater, proceed to 225.
Step 290. Turn off heater, Proceed to 290.
Step 291. Turn off pump. Proceed to 294.
Step 294. Display last valid temperature. Proceed to
280.
Step 280. Reset 30 minute pump off timer. Proceed to
292.
Step 292. Has a button on control panel been pressed
in the last 24 hours? If yes, branch to 225. If not,
branch to 293.
Step 293. Shift to economy mode. Proceed to 225.
Step 225. Proceed to Safety Circuit Chart A.
FIG. 14
Step 275. Once selected by "mode" selection, main
safety program branches into economy mode and proceeds to
300.
Step 300. Program checks for filter cycle. If filter
pump is on, program branches to 301, otherwise to 225.
Step 301. Read temperature 1 and store.
Step 302. Read temperature 2 and store.
Step 303. Select lowest of the two temperature
readings.
Step 304. If spa water temperature is equal or
greater than set temperature, branch to 305; otherwise
branch to 306.
CA 02582175 2007-03-23
23
Step 305. Turn heater off, proceed to 310.
Step 310. Display last valid temperature. Proceed to
308.
Step 306. Is spa more than .1 degree below set
temperature? If yes, branch to 307, otherwise branch to
310.
Step 307. Turn heater on. Proceed to 310.
Step 308. Has a control panel button been pressed in
the last 24 hours? If yes, branch to 225. If not, branch
to 309.
Step 309. Shift to standby mode and proceed to 225.
FIG. 15
Step 275. Once selected by "mode" selection, main
safety program branches into standby mode and proceeds to
325.
Step 325. Program checks for filter cycle. If filter
pump is on, program branches to 326, otherwise to 225.
Step 326. Read water temperature 1 and proceed to
327.
Step 327. Need water temperature 2 and proceed to
328.
Step 329. Compare spa water temperature to 15 degrees
below set temperature. If spa temperature is less than 15
degrees below set temperature, proceed to 328, otherwise
329.
Step 332. Turn on heater and proceed to 225.
Step 328. Select lowest of the two temperature
readings and proceed to 329.
As can be seen from the foregoing specification and
drawings, a spa control system is disclosed which is self
contained with a plurality of sensors located adjacent the
heater element for both temperature regulation and
limiting. In the preferred embodiment, the heater and
control system are attached together in adjacent proximity,
as illustrated in FIG. 1 and FIG. 2B. This provides the
greatest protection from mechanical hazards and facilitates
CA 02582175 2007-03-23
24
the sensing of critical parameters, such as water
temperature and water presence. In this preferred
embodiment also, a microcomputer is the central processing
unit, which receives data from a plurality of sensors in
and adjacent to the heater, which provides data for the
intelligent management of the user's desires. These user's
desires are provided to the control microcomputer via
control panels which provide a plurality of easy access for
activating functions and features of the spa.
Additionally, integrated as a part of the system
interconnect board in the control system, are not only the
microcomputer, but also the safety circuity which detects
and monitors the integrity of the system ground. In
addition, as shown in FIG. 2A, there is a ground fault
circuit interrupter circuit which shuts down the system
when an insulation failure occurs and there is a short to
the bather's water of voltage. All of these functions are
self-contained within the control system circuitry and
heater, and require no other connection than pumping from
or to a pump, power hookup with a ground, and a control
panel connection.
In the installation of such a preferred embodiment at
the factory, ease of assembly into the spa is facilitated
by eliminating external temperature sensors employed in
previously known systems, since the sensors are contained
within the system enclosure and heater assembly (FIG. 2B).
Also eliminated are any calibration requirements for
mechanical switches and sensors which might need
adjustments. Pumps, blowers and lights are plugably
connected to the control system. The user is protected
from connection to the supply voltage by the containment of
all electrical components within the heater housing and
enclosure structure, which is hooked to earth ground.
When the control system is initially energized, the
microprocessor checks for presence of water, and if
present, starts the pump. As described above, the presence
of water can be detected in accordance with aspects of the
CA 02582175 2007-03-23
invention by either the use of water as a conductor, and
detecting the flow of electrical current through the water,
and/or by use of the technique described with respect to
FIG. 7B. (Of course, other water detection techniques
5 could also be employed in the system of FIG. 1, including
the conventional mechanical, optical or ultrasonic flow
sensors.) If the routine of FIG. 7B is repeated at a
slow enough cycle rate, the system will not overheat.
If repeated loops through this software routine are
10 executed at frequent intervals, and no water is present,
the temperature of one of the temperature sensors will
eventually exceed 118 F, and the hardware high limit
circuit will shut down certain aspects of the controller,
including the heater as at step 228. As an alternative to
15 waiting for the hardware high limit circuit to shut down
powered elements, the first detection of a temperature
difference exceeding a predetermined amount, or the
occurrence of other faults, can be treated by the
controller 35 as a serious fault condition, with the
20 controller causing shutdown of all output relays (e.g. step
362 of FIG 7B). The system may be configured to require a
manual restart to be returned to normal operation.
After the water presence test has determined that
water is present in the heater housing, the microprocessor
25 reads the temperature sensors, calibrates them, and upon
determination that all sub-systems of the control system
are within tolerance, starts up the heater, if necessary.
When the spa water reaches the set temperature, the heater
is turned off, and once the heater element has cooled down,
the pump is turned off. Every selected time period, the
pump is started up, drawing water through the heater and
temperature sensor array. If heat is needed to hold the
spa water at the desired temperature, the heater is turned
on. If not, then the pump is shut down for a time
interval. This time interval is adjusted based on the rate
of heat loss from the spa. If the rate of loss is low, the
time interval can be extended to reduce wear on the pump.
CA 02582175 2007-03-23
26
The spa is generally started in the standard mode,
where the set temperature is maintained by the controller
as described. When the pump is not running, the
temperatures the sensors read do not necessarily reflect
the actual spa temperature, due to changes in temperature
in the spa equipment environment. Therefore, the last
known valid temperature is displayed on the control panel,
and it does not change until the pump starts up and runs
again on its time interval circulation to check spa
temperature.
If the user of the spa has not activated a feature of
the spa for a period of time, via the control panel, say 12
hours, the spa can automatically shift into a lower energy
consumption state, shown as "economy," where the set
temperature is only reached when the spa is filtering.
Again, if no activity is experienced at the control panel,
the spa can automatically shift into an even lower energy
consumption state, the "standby" mode. In the "economy"
mode, the last known valid temperature is displayed while
the filter pump is not running, and actual temperature is
displayed when the pump is running. To warn the user of
the mode selection, the display of temperature is
alternated with the message "econ".
When in the standby mode, no temperature is displayed,
just the message "stby", and the spa pump is filtered on
user set or default cycles. The heater is activated only
to maintain the spa water at 15 to 20 F below the set
temperature to reduce energy consumption and the need for
sanitation chemicals.
At any time, if the proper ground is damaged or
removed from the spa, the microprocessor disconnects the
peripheral equipment, including the heater, and provides an
error message to the control panel to warn the users, and
provide a diagnostic message to assist in curing the
problem. This is accomplished by the GID, FIG. 5. If
there is an actual short to ground through the ground wire,
the system can be shut down by either a ground current
CA 02582175 2007-03-23
27
detector as in FIG. 6, or a ground fault circuit
interrupter, as in FIG. 4.
If there is an over heat condition, the various
software detection methods shut off the heater, but if
there is a high limit value of over 118-122 F, the system
trips the electronic hookup high limit associated with each
temperature sensor. This opens a different set of relays
from the temperature regulation relays, shutting down the
heater until the temperature falls below a safe
temperature, and the system is re-set from the control
panel.
A detailed reference summary for exemplary elements
shown in the figures for the exemplary embodiment follows:
FIG. 1
Reference Description
1 Spa with water
2 Electronic control system
3 Heater assembly
4 Pump 1
5 Pump 2
6 Air blower
7 Light
8 Control panel
9 Control panel connecting cable
10 Auxiliary control panel
11 Auxiliary control panel cable
12 Spa skimmer
13 Spa water pumping
14 Electrical cable interconnect
15 Electrical service supple cable
16 Earth ground
17 Suction fitting
18 Jet therapy fitting
19 Air blower supply pipe
FIG. 2A
Reference Description
21 Display of information
22 Panel touch pads
23 Main circuit board
24 Isolation transformer
25 GFCI Torroid 1
26 GFCI Torroid 2
27 GFCI circuitry
28 Ground Integrity
CA 02582175 2007-03-23
28
29 Ground Current Detector
30 GCD Torroid
31 Sensory Assembly 1, temp & H20 detect
32 Sensory Assembly 2, temp & H20 detect
33 High limit circuit
34 Relay drivers
35 Microcomputer
36 Relays
37 Heater power interconnect
38 GFCI Torroid 1 interconnect
39 GFCI Torroid 2 interconnect
40 Temp sensor interconnect
41 GCD Torroid interconnect
42 Heater element
FIG. 3
Reference Description
22 Control panel
3 Heater assembly
16 Earth ground
31, 32 Temperature sensor assembly
44, 77 Electrical connection leads
78, 79, 82, 83 Resistor 430 kohm
80, 81 Resistor 820 kohm
84, 115 Resistor 10 kohm
113,112,85,94,98,107 Resistor 20 kohm
86, 92 Capacitor 0.1 microfarad
87, 93 Capacitor 22 microfarad
88, 95 Resistor 2 kohm
122,89,97,104, 105 Op Amp LM324
90 Op Amp LM662
91 Resistor 68 kohm
96, 103 Resistor 1 kohm
99 MC145041 A/D converter
110, 118 4081 B Gate
101, 108 12-7 kohm resistor
102, 106 1 meg ohm
109, 110, ill Diode 1N4003
114 Capacitor 1.0 microfarad
140 Diode 1N4754
117 Circuit connection to Figure 4
119 Resistor 4-99 kohm
120 Resistor 6 kohm
121 Thermal cutoff
123 LED red.
124 Output to heater
125 Power into heater
126 Heater relay
127 Output to heater
128 Power into heater
129, 130 High limit relay
131, 132 Darlington relay drivers
133 Transistor 2N2222
CA 02582175 2007-03-23
29
FIG. 4
Reference Description
25 Torroid 1/200
26 Torroid 1/1000
35 Computer
52 Relay D&B T90
53, 76 Diode 1N4003
54 Transistor 2N2222
55 Resistor 20K
56 Resistor 2K
57 Resistor 200 ohm
58 Capacitor 22 uf
59, 72 Capacitor .001 uf
60 Resistor 100 kohm
61 Resistor 220 kohm
62, 67 Resistor 260 kohm
63, 64, 69, 70 Diode 1N914
65 Operational amplifier 4M324
66 Capacitor 33 pf
68 Resistor 3.3 meg ohm
71 Capacitor 0.1 uf
73 Resistor 15K
74 Resistor 470 ohm
75 Capacitor .01 uf
150 Sense circuit
FIG. 5
Reference Description
43 Neon bulb limiting resistor
44 Photo resistor
45 Circuit ground
46 +5 volts
42 Heater element
3 Heater assembly
50 Heater housing
36 Relays
16 Earth ground
28 Ground integrity detector housing
35 Microcomputer
20 Neon bulb
FIG. 6
Reference Description
47 Bridge rectifier, 1 amp
48 Capacitor, 22 uf
49 Resistor, 10 kohm
Heater housing
51 Bleed resistor, 100 kohm
50 42 Heater element
3 Heater housing
CA 02582175 2007-03-23
36 Relay
30 Torroid 1/1,000 turns
16 Earth ground
34 Relay drivers
5 45 Circuit ground
Microcomputer
152 Sense circuit
FIG. 7A
10 Reference Description
31 temperature sensor assembly
31A sensor housing
31B insulating bushing
142 potting compound
15 143 wire
144 wires
The embodiments shown are merely illustrative of the
present invention. Many other examples of the embodiments
20 set forth above and other modifications to the spa control
system may be made without departing from the scope of this
invention. It is understood that the details shown herein
are to be interpreted as illustrative and not in a limiting
sense.
