1. Field of the Invention
The present invention relates generally to heaters and, more specifically, to bathtub heaters.
2. Description of the Related Art
While individuals may like to take long baths, their bathtub water may cool over time to an uncomfortable temperature. This may require the individual to add more hot water to the tub and drain out some of the cool water to keep the bath water at a constant level. Further, as water is added and drained, soap, bath scents, etc. may need to be added. This may interrupt the bath several times over the life of the bath.
In various embodiments, a bathtub heating system for heating a bathtub fluid (e.g., water, mud, etc.) in a bathtub may include a main unit and a bathtub heater coupled through tubing. In some embodiments, the bathtub heating system may detect the temperature of water in the bathtub and may apply heat to the bathtub fluid to maintain a constant temperature (or change the temperature of the bathtub fluid at the user's direction). In some embodiments, as a user adds hot or cold bathtub fluid to the bathtub, the bathtub heating system may adjust the heating of the bathtub heating system to approximately maintain the new detected temperature of the bathtub fluid (or to provide a user indicated and/or predetermined temperature/time profile). In some embodiments, the bathtub heating system may also dispense bath oils, soaps, scents, etc., to the bathtub fluid.
In some embodiments, the main unit may include three compartments (e.g., one compartment for storage space for items to use, for example, with the bath (such as scents, soaps, and bath oils), one compartment for storage of the bathtub heater and tubing, and one compartment (which may be hidden) for the main unit heating elements, pumps, controls, etc. Other configurations are also contemplated. In some embodiments, the pumps may include thermal expansion pumps (other pumps are also contemplated). In some embodiments, the main unit may heat a fluid and pump the fluid through the tubing to a heat exchanger element in the bathtub heater located at the bathtub. The heat exchanger element may place the fluid in thermal contact (which may not be actual contact) with bathtub fluid to add heat to the bathtub fluid. The fluid may then flow back through another compartment of the tubing to the main unit where the fluid may again be heated. In some embodiments, the fluid may be the bathtub fluid. The bathtub fluid may be pumped to the main unit, heated, and returned to the bathtub at the bathtub heater.
In some embodiments, the heated fluid at the bathtub heater may flow through an inlet nozzle and along an interior pathway of the bathtub heater. The interior pathway may include interior walls to direct the fluid throughout the interior of the heat exchanger element. In some embodiments, the fluid may be directed through an interior inlet through a driving mechanism with external blades to turn and direct external bathwater over the surface of the heat exchanger element. In some embodiments, the heat exchanger and/or driving mechanism may be mounted at an angle to the bathtub wall to direct water in a vertical direction upward (as well as side to side). Other directions are also contemplated (e.g., diagonally up or down, or any of other various directions). In some embodiments, the main unit and/or bathtub heater may be incorporated into the bathtub (e.g., in the sidewalls of the bathtub). In some embodiments, the bathtub may be a baby bathtub (other bathtubs are also contemplated).
In some embodiments, the bathtub heating system may include a heating element (e.g., wire) placed on the sides and/or bottom of the bathtub to heat the bathtub fluid in the bathtub. The bathtub heating system may have different zones of heating elements on the bathtub to direct different levels of heat to different portions of the bathtub.
In some embodiments, the bathtub heating system may use one or more temperatures sensors to monitor and approximately maintain the temperature of the bathtub fluid in the bathtub (or to provide a user indicated and/or predetermined temperature/time profile). In some embodiments, the bathtub heating system may not use a temperature sensor. For example, the bathtub heating system may use a fluid level sensor to detect when the bathtub fluid in the bathtub is at a sufficient height to operate and may apply a predetermined amount of power to the heating elements to approximately maintain the temperature of the bathtub fluid in the bathtub.
A better understanding of the present invention may be obtained when the following detailed description is considered in conjunction with the following drawings, in which:
a-b illustrate components of the main unit, according to various embodiments.
a-e illustrate a heat exchanger element for a bathtub heater, according to various embodiments.
f-g illustrate a bathtub fluid exchanger, according to an embodiment.
a-c illustrate a thermal water expansion pump, according to an embodiment.
a-b illustrate a rotatable housing for the tubing, according to an embodiment.
a-c illustrate a bathtub heating system incorporated into a bathtub, according to an embodiment.
d illustrates a bathtub heating system externally attached to the bathtub, according to an embodiment.
a-b illustrate a bathtub heating system for a baby bathtub.
a-c illustrate a heating element on a bathtub, according to an embodiment.
a-b illustrate an electrical schematic of the bathtub heating system, according to an embodiment.
While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention as defined by the appended claims. Note, the headings are for organizational purposes only and are not meant to be used to limit or interpret the description or claims. Furthermore, note that the word “may” is used throughout this application in a permissive sense (i.e., having the potential to, being able to), not a mandatory sense (i.e., must). The term “include”, and derivations thereof, mean “including, but not limited to”. The term “coupled” means “directly or indirectly connected”.
a-b illustrate components of main unit 103, according to various embodiments. As seen in
In some embodiments, main unit 103 may heat fluid 419 (e.g., see
a-g illustrate heat exchanger element 305 (which may be mounted in attachment mechanism 501), according to various embodiments. In some embodiments, heated fluid 419 from tube 107 may flow through inlet nozzle 401 and along an interior pathway of heat exchanger element 305. The interior pathway may include an interior routing element (e.g., interior walls 405). Interior walls 405 may extend between top plate 491 and lower plate 493 of bathtub heater 105 to direct fluid 419 throughout the interior of heat exchanger element 305. For example, the flow path may direct fluid 419 to flow throughout a substantial portion of the interior volume of bathtub heater 105. Other configurations of interior walls 405 are also contemplated.
In some embodiments, fluid 419 may be directed through interior inlet 407 through driving mechanism 411 and through interior outlet 409 to continue along the interior path. Fluid 419 may flow, for example, over one or more internal blades 433 in driving mechanism 411 which may be coupled through shaft 415 to exterior blades 413. Exterior blades 413 may thus turn and direct external bathtub fluid 104 over the outer casing (e.g., which may include top plate 491 and lower plate 493) of heat exchanger element 305 (e.g., see fluid flow lines 417 in
As seen in
Also as seen in
In some embodiments, heat exchanger element 305 may be coupled to positioning component 421 of bathtub heater 105. For example, screws (or other types of fasteners) may be used to fasten heat exchanger element 305 to positioning component 421 (e.g., through fastener holes 435a-d). In some embodiments, positioning component 421 may shield at least one side of heat exchanger element 305 from the bathtub user (e.g., heat exchanger element 305 may be coupled to the under side of plastic shield 423 which may shield the user from direct contact with bathtub heater 105 while allowing bathtub fluid 104 to contact bathtub heater 105 on the under side). Other configurations are also contemplated. In some embodiments, bathtub fluid 104 may flow through slots 521 (below shield 423 and above heat exchanger element 305) (see
In some embodiments, as seen in
At 1001, fluid 419 may be pumped into main unit 103 (e.g., from return chamber 803 of tube 107) using a pumping mechanism. In some embodiments, the pumping mechanism may be a thermal expansion pump, a centrifugal pump, a kinetic pump or a positive displacement pump. Other pumps are also contemplated. In some embodiments, the pumping mechanism may include one or more expandable liners 901a,b (the operation of which is further described, for example, in
At 1003, fluid 419 entering main unit 103 may be heated by heating element 425. In some embodiments, heating element 425 may heat fluid 419 by converting electrical energy (e.g., applied through contacts 997 from electrical line 995) to heat (e.g., through an electrical current applied to a resistive element). In some embodiments, heating element 425 may include electrical insulation to prevent electricity from flowing through to fluid 419. The insulation may allow heat to pass through to fluid 419. Other heating elements and heating element configurations are also contemplated.
At 1005, heated fluid 419 may be pumped out of main unit 103 and into warm chamber 801 (e.g., pumped by thermal expansion pumps 1201).
At 1007, fluid 419 from warm chamber 801 may flow to bathtub heater 105 to heat bathtub fluid 104. In some embodiments, fluid 419 may flow through heat exchanger element 305 in thermal contact with bathtub fluid 104. In some embodiments, the fluid may be bathtub fluid 104 (and may be released into bathtub 111 after being heated as seen in
At 1009, fluid may return to main unit 103 through return chamber 803 (e.g., as a result of pumping action from thermal expansion pumps 1201).
At 1101, expandable liner 901a may expand (e.g., see
At 1103, as expandable liner 901a expands, fluid may leave chamber 919a through check valve 917b (e.g., in direction of arrow 921b). Other fluid connection types are also contemplated. Other numbers of check valves are also contemplated (e.g., two outlet check valves may be used). The fluid may flow out of check valve 917b and into outlet chamber 919c. In some embodiments, chambers 919a-d may be separate chambers linked by one or more check valves 921a-d to maintain fluid flow in one direction. Other chamber configurations are also contemplated.
At 1105, expandable liner 901 a may collapse.
At 1107, as expandable liner 901a collapses, fluid may enter chamber 919a through check valve 917a (e.g., in direction of arrow 921a). Other fluid connection types are also contemplated. The fluid may flow into check valve 917a from heating chamber 919d. Heating chamber 919d may include heating element 425. Other placements of heating element 425 are also contemplated. In some embodiments, fluid 419 in heating chamber 919d may flow into heating chamber 919d through inlet valve 431 coupled to return chamber 803 of tube 107.
At 1109, as expandable liner 901 expands and collapses, fluid 419 in outlet chamber 919c may enter balance chamber 951 with fluid chamber 909 separated from compressible chamber 907 by piston head 911. As expandable liner 901 initially expands and displaces fluid 419, some of fluid 419 may displace piston head 911 (resulting in compression of a fluid (e.g., air) in compressible chamber 907).
At 1111, as the pressure of the fluid in chamber 907 rises, fluid 419 may begin to flow through outlet 913 and into warm chamber 801 of tube 107. As the expandable liner 901 expands and collapses, the pressure in chamber 907 may fluctuate, however, fluid 419 may continue to flow through outlet 913.
In an embodiment with two expandable liners 901 (e.g., as shown in
In some embodiments, expandable liners 901a,b may expand and collapse together. Other expansion/collapse timing configurations are also contemplated. Other numbers of expandable liners 901 are also contemplated (e.g., 3, 4, 10, etc.). In some embodiments, expandable liner 901 may be inside chamber 919a inside of main unit 103. Check valves 917 may prevent fluid 419 from moving back and forth in chamber 919a as expandable liner 901 expands and collapses. Fluid 419 exiting check valves 917b and 917d may enter outlet chamber 919c with chambers 907/909 (which may be isolated from the interior of main unit 103).
a-c illustrate thermal expansion pump 1201 with expandable liner 901, according to an embodiment.
At 1301, fluid 419 may enter inlet 1205 to at least partially fill an interior volume between heating element 1203 and expandable liner 901.
At 1303, inlet 1205 may be sealed closed. For example, an electric current flowing through solenoid coil 1207 may cause solenoid coil 1207 to push plunger 1209 closed. Washer 1211 (e.g., a rubber seal washer) at the end of plunger 1209 may form a seal on or in inlet 1205.
At 1305, current may be applied to heating element 1203. For example, current may be applied through contacts 1215 (which may be alternating current (AC) or direct current (DC) contacts). In some embodiments, contacts 1215 may be secured in place through end cap 1213 that also secures heating element 1203 and expandable liner 901. In some embodiments, end cap 1213 (and, for example, inlet 1205) may be made of brass. Other materials are also contemplated (e.g., plastic). In some embodiments, contacts 1215 may be insulated to apply the electrical current only to heating element 1203 (and not, for example, to end cap 1213 or surrounding fluid 419).
At 1307, fluid 419 inside expandable liner 901 may expand causing expandable liner 901 to expand. In some embodiments, fluid 419 may turn into steam during the expansion. In some embodiments, the amount of fluid 419 in expandable liner 901 (e.g., as determined by the amount of space between the components inside collapsed liner 901) and the amount of heat supplied from heating element 1203 may be coordinated to expand expandable liner 901 to a predetermined extent. In some embodiments, fluid pump chamber shield 903 (e.g., a plastic shell) may at least partially surround expandable liner 901 to limit expansion of expandable liner 901. Limiting the expansion may increase the life expectancy of expandable liner 901 by preventing over expansion (which may lead to weak spots and/or ruptures in expandable liner 901). In some embodiments, fluid pump chamber shield 903 may be coupled to end cap 1213 and inlet 1205. Other configurations for fluid pump chamber shield 903 are also contemplated. As expandable liner 901 expands, fluid 419 around expandable liner 901 may be displaced (causing, for example, fluid 419 to flow through check valve 917b).
At 1309, the current to heating element 1203 and solenoid coil 1207 may be discontinued.
At 1311, spring 1297 may bias open plunger 1209. As plunger 1209 opens, washer/seal 1211 may be moved away from inlet 1205. Fluid 419 (which may be at least partially expanded) in expandable liner 901 may at least partially leave the interior of expandable liner 901 through inlet 1205.
At 1313, expandable liner 901 may collapse. Collapsing liner 901 may create a void around expandable liner 901 which may be filled by surrounding fluid 419. Additional fluid 419 may enter chamber 919a through check valve 917a.
In some embodiments, bathtub heater 105 may also include processor 1401c coupled to one or more temperature sensors 1403c,d and/or pressure sensors (e.g., see
In some embodiments, processors 1401 may operate and control the timing of valve coils 1207a,b and switches 1409a-f (e.g., solid state and/or in-line TRIAC switches (TRIode for Alternating Current Switches)) to the heating coils (e.g., heating element 425, and 1203a,b). If the detected temperatures exceed a predetermined temperature or a system failure is detected, processors 1401 may discontinue electrical current to one or more heating elements 425, 1203a,b (e.g., by switching off the current through switches 1409a-f). In one configuration, processor 1401a may operate valve coil 1207a and switch on current through switches 1409a-c if a temperature through temperature sensor 1403a indicates a temperature below an expected threshold and processor 1401b may operate valve coil 1207b and switch on current through switches 1409d-f if a temperature through temperature sensor 1403b indicates a temperature below a predetermined threshold. If one of processors 1401 detects a temperature exceeding a predetermined threshold, the switches corresponding to the processor may not be activated and current may not flow to one or more heating elements 425, 1203a,b. For example, a predetermined threshold for fluid 419 may be approximately 130 degrees F. Other thresholds are also contemplated (e.g., 140 degrees F.). In some embodiments, two switches may be required (e.g., switches 1409b,e) to be on for a respective heating element (e.g., heating element 1203a) to activate (this may provide additional safety in case one or more sensors and/or processors fails and causes continuous or sporadic operation of their corresponding switch). Processors 1401 may also base operating decisions on comparing the pressure detected through pressure sensor 1405 to a predetermined pressure threshold and on information from processor 1401c. For example, processor 1401c may compare temperatures from temperature sensors 1403c,d (e.g., temperature sensor 1403c for the bathtub fluid temperature and temperature sensor 1403d for the fluid temperature) to predetermined temperature thresholds and may determine whether bathtub fluid 104 is in bathtub 111 (e.g., through a signal from fluid detection sensor 1407). Since a failed temperature sensor may not necessarily go to a detectable state, the differences in a multiple thermal sensor system may be used to detect a sensor failure that may result in bringing bathtub heating system 100 to a fail-safe condition. In some embodiments, only one temperature sensor (e.g., temperature sensor 1403c) may be used (other numbers of temperature and pressure sensors are also contemplated). In some embodiments, a predetermined threshold for the bathtub fluid temperature may be approximately 115 degrees F. Other bathtub fluid temperature thresholds are also contemplated. In some embodiments, processor 1401c may send the information from the sensors or a positive/negative signal to one or more processors 1401. Processors 1401 may use this information to further determine whether to activate/deactivate valve coils 1207a,b and/or switches 1409a-f. In some embodiments, processors 1401 may not activate (or may deactivate) thermal expansion pumps 1201 if the detected pressure of fluid 419 is greater than approximately 30 pounds per square inch (PSI). Other thresholds are also contemplated (e.g., approximately 40 PSI).
In some embodiments, processors 1401 may monitor the detected temperatures (e.g., of bathtub fluid 104) from temperature sensor 1403c to operate heating elements 425, 1203a,b to attempt to maintain the detected bathtub temperature constant. The detected fluid temperatures (e.g., from temperature sensors 1403a,b,d) may be used to determine a heat loss level in fluid 419 between main unit 103 and bathtub heater 105. Additional heat may be added if heat loss is above a predetermined threshold. Processors 1401 may use the detected pressure (e.g., from pressure sensor 1405) to determine if there is a break in the system (e.g., a loss in pressure) or, for example, if the hose is kinked (e.g., spike in pressure). In some embodiments, pressure sensor 1405 may be placed outside of both chambers 919a,b (e.g., to detect a rupture in expandable liner 901, or other failure). Placement outside both of chambers 919a,b in outlet chamber 919c may allow the pressure sensor to detect a pressure affected by both chambers 919a,b and the pressure inside tubing 107. In some embodiments, pressure sensors may be placed inside thermal expansion pumps 1201. Other sensor locations are also contemplated. In some embodiments, both fluid 419 in bathtub heating system 100 and the bathtub fluid temperature may be monitored and/or modeled.
In some embodiments, if an error is detected, the heating elements (e.g., heating elements 425, 1203a,b) and/or the pumps (e.g., thermal expansion pumps 1201a,b) may be deactivated and an indication (e.g., audio and/or visual) may be sent to the user. Other components may also be deactivated. Processors 1401 may reset after power is turned off and back on to bathtub heating system 100. In some embodiments, an indication of the error and/or error type may be stored on a FLASH memory (or other type of memory) accessible to processors 1401 (e.g., a FLASH memory resident on one or more of processors 1401). The FLASH memory may be read by processors 1401 on start-up and, for example, if the error indicated is a severe error, bathtub heating system 100 may not be activated by processors 1401 when the user attempts to activate bathtub heating system 100. In some embodiments, processors 1401 may be programmed to recognize severe errors that indicate a permanent system malfunction (e.g., an inactive fluid level sensor) and potentially correctable errors (e.g., a spike in fluid pressure indicating tube 107 may have been kinked). If the error is potentially correctable, processors 1401 may attempt to resume normal operating when power is restored. Processors 1401 may store an indication of a severe error if two or more potentially correctable errors are detected in a row. Other error types are also contemplated.
In some embodiments, processor 1401c may be further coupled to on/off switch 1419 and one or more light emitting diodes (LEDs) 1421 to convey visual information to a user (e.g., unit operating, unit error, etc.) For example, a blue and a pink LED may be provided and may convey information to the user (e.g., pulsing blue—bathtub heating system 100 is waiting for the proper fluid level; steady blue—fluid level is correct, bathtub heating system 100 is monitoring the temperature; slight pink—temperature is stabilizing; solid pink—desired temperature is detected and is being maintained). Other information formats (e.g., auditory signals) are also contemplated. Other visual interfaces are also contemplated (e.g., an LED display).
In some embodiments, on/off switch may include additional switch options (e.g., a rheostat to increase/decrease temperature). Heating elements 425, 1203a,b may also be coupled to respective thermal switches 1411a-c (e.g., passive thermal switches) which may act as additional safety elements to cut current to a heating element if the local detected temperature exceeds a predetermined limit (e.g., a physical limit for a part in thermal switch 1411a-c). In some embodiments, passive pressure switches (e.g., which detect the pressure of fluid 419) may also be coupled to the power supply to cut power if the pressure exceeds or is below a predetermined threshold (e.g., as set by the physical characteristics of the passive pressure switch). Other sensors are also contemplated. In some embodiments, a power supply may include power source 1415 (e.g., an alternating current (AC) plug into an AC outlet), fuse 1417, and/or an AC/DC power supply/converter 1423 (e.g., with a transformer). In some embodiments, bathtub heating system 100 may also include a ground-fault-interrupter circuit that is collocated with the AC plug. In some embodiments, the AC power may be delivered to main unit 103 which may be remote from bathtub fluid 104 to increase user safety (e.g., lower the likelihood of electrocution due to a short) and for passing safety regulations. Direct current (e.g., from the AC/DC power supply) may power processors 1401 and switch lines (e.g., 3.3 volts). In some embodiments, the electrical power supplied to bathtub heater 105 may be small (e.g., 3.3 volts or less than equivalent power of 2 AA batteries). Other power levels are also contemplated. In some embodiments, DC power may be supplied to bathtub heater 105 (e.g., to power a heating element located in bathtub heater 105). In some embodiments, powering the heating element with DC power (e.g., to meet safety regulations) may require a substantial transformer diameter (e.g., to pass a DC current of approximately 100 amps at 18 volts). Other power levels are also contemplated.
In some embodiments, processors 1401 may compare readings (e.g., from various temperature and/or pressure sensors) and may shut down bathtub heating system 100 if one or more readings are not within predetermined operating limits. In some embodiments, processors 1401 may compare detected temperatures and/or pressures to a real-time computer model and/or simulation for bathtub heating system 100 and/or bathtub fluid 104 to predict the temperature of fluid 419 and/or bathtub fluid 104 that should be detected. In some embodiments, if the detected temperature is outside a range of predicted values (plus or minus a buffer range), bathtub heating system 100 may shut down (e.g., to prevent excessive heating). In some embodiments, a history of detected temperatures and/or pressures may be compared to a predicted track of temperatures and/or pressures. The comparison may be used to detect problems with bathtub heating system 100. For example, if one or more of thermal expansion pumps 1201 is activated, and the detected pressures do not indicate a rise in pressure, processors 1401 may determine that thermal expansion pump 1201 has failed (e.g., expandable liner 901 has ruptured). In some embodiments, an indication of the error (e.g., as a severe error) may be written to the FLASH memory. In some embodiments, the indication may be detected by processors 1401 the next time bathtub heating system 100 is activated. If the indication indicates a severe error (e.g., a ruptured expandable liner 901), processors 1401 may not allow bathtub heating system 100 to activate. In some embodiments, the indication may not indicate a severe error. For example, if a spike in pressure was detected (indicating, for example, a kinked tubing 107), processors 1401 may flash an indicator to the user (e.g., through LEDs) and may deactivate bathtub heating system 100 after writing an indication of the error (which may be indicated temporary) to the FLASH. Upon reactivation, processors 1401 may not inhibit activation (e.g., the user may have un-kinked tubing 107) until another error is detected.
a-b illustrate an embodiment of rotatable housing 1600 for spooling mechanism 1501. In some embodiments, the end of tubing 107 may be coupled to warm inlet nozzle 1601 and cool inlet nozzle 1603 at the center of spooling mechanism 1501. Interior compartment 1605 may provide a pathway for warm fluid (e.g., outgoing fluid 419) and interior compartment 1607 may provide a pathway for cool fluid (e.g., incoming fluid 419). Warm fluid may flow through interior compartment 1607 from inlet nozzle 1609, and cool fluid may flow from cool inlet nozzle 1603 through interior compartment 1607 (which may wrap around interior compartment 1605) to cool inlet nozzle 1611. Rotatable housing 1600 may include fixed portion 1617 and rotating portion 1615. In some embodiments, power and control lines 1613a may enter the side of fixed portion 1617 and may transfer power/control signals to respective power and control lines 1613b (e.g., extruded in tubing 107) through slip ring interface 1619 including slip rings 1621 and corresponding slip ring conductive tracks 1623. In some embodiments, internal o-rings 1625 may maintain a seal to prevent fluid from leaking out of the interior of rotatable housing 1600 while allowing rotating portion 1615 to rotate relative to fixed portion 1617. Inlet nozzle 1609 may be coupled to outlet 913 (e.g., directly or through a tube) and inlet nozzle 1611 may be coupled to inlet valve 431 (see
At 1701, a user may take bathtub heater 105 out of the main unit box (e.g., lower compartment 211) and may couple bathtub heater 105 to bathtub 111. In some embodiments, the user may couple bathtub heater 105 to bathtub 111 by unfolding bathtub heater 105 and placing suction cup 505 in contact with the bathtub wall and applying pressure to engage suction cup 505. In some embodiments, the user may also lower suction cup arm 507. The user may also place suction cups 703 of tube clip 513 in contact with the outer wall of bathtub 111 and may apply pressure to engage suction cups 703 (the user may also lower lever arms 701). The user may further insert tubing 107 (coupled to bathtub heater 105) into tube clip 513. In some embodiments, assembly by the user may not be needed (e.g., see embodiment shown in
At 1703, the user may activate bathtub heating system 100. For example, the user may press on/off switch 1419, press a button, etc. In some embodiments, bathtub heating system 100 may automatically activate when it detects sufficient bathtub fluid 104 to operate (e.g., no user interaction may be required).
At 1705, bathtub heating system 100 may determine if the fluid level of bathtub 111 is sufficient for operating. For example, a fluid level detection sensor 1407 (see also fluid level sensor 2051 in
At 1707, bathtub heating system 100 may detect the temperature of bathtub fluid 104. In some embodiments, bathtub heating system 100 may monitor the temperature of bathtub fluid 104 (e.g., using temperature sensors 1403c,d) through an initial temperature adjustment period to determine when the temperature has stabilized (e.g., remained near constant over a predetermined duration such as 20 seconds). The initial temperature adjustment period may also correspond to a period during which a detected temperature change rate of the bathtub fluid exceeds a threshold (e.g., ±2 degrees F. in a time range of 1-2 seconds). Other thresholds are also contemplated. In some embodiments, the initial temperature adjustment period may be a fixed time (e.g., 3 minutes as indicated by a timer presented to the user). At the conclusion of the fixed time, the detected temperature may become the control set point temperature to maintain by the bathtub heating system. Other time periods are also contemplated. In some embodiments, a user may press a button (or other user control) to signal when the user has bathtub fluid 104 at the desired temperature to maintain. Waiting for the temperature to stabilize may allow the bathtub fluid temperature to be adjusted by the user (e.g., by adding/draining hot/cold bathtub fluid 104) and for bathtub fluid 104 to sufficiently mix. In some embodiments, a slight pink LED may activate to show the user bathtub heating system 100 is waiting for the temperature to stabilize. Other indicators are also contemplated. In some embodiments, the bathtub heating system may not detect a temperature of the bathtub fluid 104.
At 1709, bathtub heating system 100 may maintain the detected bathtub fluid temperature. In some embodiments, a solid pink LED may be activated to indicate the current temperature is being maintained. Other indicators are also contemplated. In some embodiments, as bathtub heating system 100 detects a temperature drop, bathtub heating system 100 may increase the temperature and/or flow rate of fluid 419. In some embodiments, if a detected temperature change is greater than a predetermined threshold (e.g., 2 degrees F.), bathtub heating system 100 may indicate to the user that a new temperature is being detected (e.g., through a slight pink LED) and then the new temperature is being maintained (e.g., through a solid pink LED). For example, the user may change the temperature of bathtub fluid 104 during the bath (e.g., by adding/draining hot/cold bathtub fluid 104). In some embodiments, the temperature change threshold (for which a new temperature will be detected and maintained) may be set by the user (e.g., to increase/decrease the sensitivity of bathtub heating system 100). This new temperature (i.e., second bathtub fluid temperature) may be detected during a subsequent temperature adjustment period (i.e., subsequent to the initial temperature adjustment period). In some embodiments, a predetermined power may be applied to the heating element to approximately maintain the temperature of the bathtub fluid without detecting a temperature of the bathtub fluid.
In some embodiments, bathtub heating system 100 may cycle on and off during use (e.g., while providing heat). The bathtub heating system 100 may continue to monitor temperature continuously (e.g., even during off periods). If the heating element is off and bathtub heating system 100 detects a temperature increase, the temperature increase may be attributed to a user water change. Further, if the temperature stays constant after the detected change, the change may be attributed to a water change. If the heating element is on and the temperature of bathing fluid 104 is increasing more than a rate of approximately 0.5 degrees F. in approximately a range of 2-3 minutes (and the temperature does not increase when the heating element is off) the temperature change may be attributed to a low water level (e.g., below the minimum operating line). Other rates and ranges for the rates are also contemplated. In some embodiments, a predetermined amount of heat may be provided to approximately maintain a constant temperature without measuring a temperature associated with the bathing fluid. For example, a bathtub fluid 104 may be predetermined to lose approximately 1 degree F. every 17 minutes without heat applied and a heat calculation may be performed to determine how much heat to provide the bathtub fluid 104 to offset the loss to maintain approximately a constant temperature. Other predetermined losses are also contemplated. For example, a different bathtub in a different environment may experience a loss of 2 degrees F. every 10 minutes.
At 1711, the user may deactivate bathtub heating system 100 and may place bathtub heater 105 back in the main unit box (e.g., lower compartment 211). In some embodiments, the user may deactivate bathtub heating system 100 by pressing on/off switch 1419, press a button, etc. In some embodiments, bathtub heating system 100 may automatically deactivate when the fluid level detection sensor 1407 detects the fluid level has fallen below a predetermined level (e.g., due to the user draining bathtub fluid 104 and/or lifting bathtub heater 105 out of bathtub fluid 104). In some embodiments, the user may disengage suction cup 505 by lifting up on suction cup arm 507 and may disengage suction cups 703 by lifting up on suction cup arms 701.
In various embodiments, bathtub heating system 100 may have other configurations. For example, bathtub heating system 100 may incorporated into bathtub 111. For example, as seen in
a illustrates an embodiment of main unit 103 configured inside the bathtub walls and coupled to heat exchangers that are coupled to the bathtub walls. While main unit 103 is shown below bathtub 111, other locations of main unit 103 are also contemplated (e.g., next to a side wall of bathtub 111, in front of bathtub 111, behind bathtub 111, in a wall located next to bathtub 111, etc.). Main unit 103 may include heating element 425 and the pump (e.g., thermal expansion pump 1201). Fluid 419 may be heated by heating element 425 in main unit 103 and pumped through tubing 1801 (which may be dual chambered tubing) to and from a heat exchanger element 305 mounted in side units 1803 (e.g., through screws or other fasteners). Bathtub fluid 104 may flow through screens 1805 and into thermal contact with heat exchanger elements 305 in side units 1803. Driving mechanisms 411 may facilitate bathtub fluid flow over heat exchanger elements 305 and back and forth to bathtub 111. In some embodiments, screens 1805 may be made of plastic or another insulating material. Other configurations and materials for screens 1805 are also contemplated (e.g., screens 1805 may be flush with the bathtub walls). In some embodiments, side units 1803 may also be made of plastic or another material. In some embodiments, the bathtub walls between screens 1805 and side units 1803 may have apertures to facilitate bathtub fluid flow between side units 1803 and screens 1805. In some embodiments, screen 1805 may include a filter to filter out debris, etc. In some embodiments, the filter may be replaceable and/or cleanable.
b illustrates an embodiment of main unit 103 configured inside the bathtub walls to receive bathtub fluid 104 through tubes 1801 from screens 1805. Bathtub fluid 104 may be pumped to main unit 103, heated, and pumped back through tubes 1801 back to bathtub 111. In some embodiments, bathtub fluid 104 may be pumped to main unit 103 through tube 1801 on one side of bathtub 111 and back to bathtub 111 through tube 1801 on the opposing side of main unit 103. In some embodiments, tubes 1801 on both sides of main unit 103 may pump fluid to and from respective sides of bathtub 111. In some embodiments, a tube chamber pulling fluid from bathtub 111 may be spaced away from the tube chamber delivering heated fluid to bathtub 111 (e.g., by spacing apart the respective tube chambers in screens 1805).
c illustrates an embodiment of main unit 103 coupled to an inside of bathtub 111. In some embodiments, main unit 103 may be coupled to the inside of bathtub 111 by an over side clip/mounting bracket 1807 and/or suction cups between main unit 103 and bathtub 111. Other coupling mechanisms are also contemplated. Main unit 103 may directly heat bathtub fluid 104 which may flow to/from main unit 103 through screen 1805. In some embodiments, main unit 103 may indirectly heat bathtub fluid 104 by heating a fluid pumped to heat exchanger 305 that is in thermal contact with bathtub fluid 104.
In some embodiments, bathtub heating system 100 may include an externally attached main unit 103 as seen in
In some embodiments, bathtub heating system 100 may be integrated into a smaller tub structure (e.g., an baby bathtub as seen in
a-c illustrate another embodiment of bathtub heating system 100. In some embodiments, bathtub heating system 100 may include heating element 2003 wrapped around a portion of bathtub 111. Heating element 2003 may include a heating wire wrapped at intervals (e.g., approximately in a range of 4-8 inches (such as 6 inches)) around at least a portion of bathtub 111 (e.g., around the bathtub bottom 2015 and sides 2013a-d). Other intervals are also contemplated (e.g., less than 1 inch, 2 inches, etc). Other heating elements are also contemplated. For example, the heating element may include a surface resistant material (such as a sprayed-on carbon film) that heats when conveying a current, hot air or water may be circulated on the outside of bathtub 111 to heat bathtub 111, etc. The heating element may be configured to evenly heat the bathtub fluid 104 in the bathtub 111 (e.g, without circulating the bathtub fluid 104). In some embodiments, insulation may be included around the sides 2013a-d and/or bottom 2015 of bathtub 111 (e.g., to prevent user contact with heating element 2003).
In various embodiments, bathtub heating system 100 may also include one or more sensors (e.g., temperature sensors 2005a,b). Sensors may be located on the outside of bathtub 111 (e.g., temperature sensor 2005a near the top of the bathtub 111 and temperature sensor 2005b near a bottom 2015 of bathtub 111 (e.g., at an area without heating element 2003), a fluid level sensor 2051 near a minimum fluid line for operation, etc). Other sensors are also contemplated (e.g., pressure sensors, pH sensors, water detection sensors, etc). In some embodiments, bathtub heating system 100 may further include a control system (e.g., including a microprocessor in control box 2009) that accesses temperature readings from temperature sensors 2005a,b and applies variable power to heating element 2003.
c illustrates an embodiment of a heating element configuration on the bathtub 111. The bathtub 111 may include 4 loops (e.g., loops 2050a-d) of heating wire (e.g., 28 gauge Nichrome wire) that each start at the front of the bathtub 111, wrap around the sides and back of the bathtub 111 and loop at the front of the bathtub 111 (see
In some embodiments, a control box 2009 may be coupled to the loops of wire to provide and control the electrical current supplied to the heating elements. In some embodiments, each loop may be controlled separately (e.g., in some embodiments, separate temperature sensors may be placed in the proximity of each loop and the current supplied to each respective loop may be varied according to the temperature detected (e.g., to keep a uniform temperature over the surface of the bathtub 111). In some embodiments, uniform power may be supplied to the heating elements without separately controlling the power level to each heating element.
In some embodiments, there may be no user controls, and bathtub heating system 100 may maintain a temperature of bathtub fluid 104 in bathtub 111. For example, at the start of a bath, the bathtub fluid temperature may be detected by temperature sensor 2005 (the initial temperature (e.g., after the temperature stabilizes) may be the control set point temperature). The control set point temperature may be maintained during the bath. In some embodiments, a user may not turn on/off bathtub heating system 100. For example, a temperature sensor 2005a and/or fluid level sensor 2051 may be placed near a minimum fluid line for operation of the bathtub heating system 100. When the user fills bathtub 111 up to temperature sensor 2005a and/or fluid level sensor 2051 (e.g., the temperature of bathtub fluid 104 may be detected by temperature sensor 2005a and/or the fluid level may be detected by the fluid level sensor 2051 as the fluid level rises above temperature sensor 2005a), bathtub heating system 100 may automatically turn on. When the user drains bathtub 111 below the level of upper temperature sensor 2005a (and/or fluid level sensor 2051), bathtub heating system 100 may automatically turn off. A rate of change in detected temperature may indicate the presence or absence of bathtub fluid 104. For example, during operation, if the temperature detected at temperature sensor 2005a is increasing quickly (e.g., above a range of approximately 1-2 degrees F. per minute), bathtub heating system 100 may determine that there is no bathtub fluid 104 in the region of temperature sensor 2005a detecting the rapid change (which may be due to heating element 2003 heating bathtub 111 without heat exchange to bathtub fluid 104). If the temperature is detected as changing within the range of approximately 1-2 degrees F. per minute, bathtub heating system 100 may determine that bathtub fluid 104 is over the level of temperature sensor 2005a. In some embodiments, two temperature sensors 2005a,b may be used (temperature sensor 2005b at a lower location in bathtub 111 and temperature sensor 2005a at an upper location in bathtub 111) to determine an average temperature of bathtub fluid 104 and/or to monitor the temperature of bathtub fluid 104 at multiple locations in bathtub 111.
In some embodiments, if the user wants to increase the temperature of bathtub fluid 104, he/she may add warmer bathtub fluid 104 (and/or drain out cooler bathtub fluid 104) to bathtub 111 to increase the average bathtub fluid temperature. In some embodiments, the average bathtub fluid temperature may be determined as the average of the temperatures detected by temperature sensors 2004a and 2005b. If the user wants a lower temperature bathtub fluid 104 he/she may add cooler bathtub fluid 104 (and/or drain out warmer bathtub fluid 104) to decrease the average fluid temperature. In some embodiments, a change in the temperature of one or more temperature sensors 2005a,b above a threshold rate of change may reset the control set point temperature. In some embodiments, bathtub heating system 100 may remain off until both temperature sensors 2005a,b are above a threshold (e.g., a temperature between 80-100 degrees F. (such as 90 F)). The temperature may raise above the threshold when the user fills bathtub 111 with warm bathtub fluid 104. In some embodiments, if either temperature sensor 2005a,b indicates a temperature below the threshold (e.g., below 90 F) and/or if the temperature is increasing above a threshold rate (e.g., above a range of approximately 1-2 degrees F. per minute) bathtub heating system 100 may turn off. In some embodiments, bathtub heating system 100 may also use an upper threshold approximately in a range of 100-120 degrees F. (e.g., if either temperature sensor 2005a,b indicates a temperature above approximately 104 F bathtub heating system 100 may turn off).
In some embodiments, when the user begins to drain bathtub 111, upper temperature sensor 2005a may no longer be covered with bathtub fluid 104. If the temperature of upper temperature sensor 2005a increases rapidly while the heating power is applied (e.g., above a range of approximately 1-2 degrees F. per minute) and/or if the temperature of upper temperature sensor 2005a differs by more than a difference approximately in range of 1-4 degrees F. (e.g., 2.5 degrees F.) from lower temperature sensor 2005b bathtub heating system 100 may turn off. Either of these conditions may occur when no bathtub fluid 104 covers upper temperature sensor 2005a. Increasing rapidly may include a rate of increase that would occur if no bathtub fluid 104 covers temperature sensor 2005 (and bathtub 111 is still being heated by the heating element). In some embodiments, bathtub heating system 100 may include only one temperature sensor (e.g., upper temperature sensor 2005a) that may detect the temperature to be maintained and detect if the bathtub fluid 104 is above a minimum operating line. Other numbers of temperature sensors are also contemplated. In some embodiments, bathtub heating system 100 may use a fluid level sensor 2051 to detect the presence of fluid (e.g., an electrical sensor, a mechanical sensor, pressure switch, etc).
In some embodiments, bathtub heating system 100 may not include a temperature sensor (e.g., bathtub heating system 100 may apply power when bathtub fluid 104 is detected through, for example, fluid level sensor 2051). In some embodiments, a power level for the heating element to maintain a temperature of a bathtub fluid in the bathtub 111 may be predetermined such that when fluid is detected at the fluid level sensor, the predetermined power may be applied to the heating element to approximately maintain the temperature. For example, bathtub heating system 100 may apply approximately 600 watts as long as bathtub fluid 104 is detected. Approximately maintaining a temperature of the bathtub fluid may include maintaining the temperature within a range of ±1 degree F. over an hour. Other ranges for approximately maintaining a temperature are also contemplated (e.g., within a range of ±5 degrees F. over an hour, etc).
In some embodiments, the bathtub heating system may decrease the temperature of the bathtub fluid over time (e.g., at a default or user specified rate and/or time). For example, the bathtub heating system may allow the temperature of the bathtub fluid to drop 0.5 to 2 degrees F. over 0.5 hours. Other cooling profiles are also contemplated (these may be user selected/entered or system determined). In some embodiments, the cooling profile may allow a user to stay in the bathtub longer without overheating.
In some embodiments, bathtub heating system 100 may include user controls. For example, bathtub heating system 100 may include an on/off switch and/or a temperature control to allow the user to increase or decrease the temperature of bathtub fluid 104. In some embodiments, a sensitivity control may be included to allow the user to adjust how quickly bathtub heating system 100 adjusts to and maintains new temperatures (e.g., the control may be set to a less sensitive setting to allow the user more time to adjust the bathtub temperature by adding/removing bathtub fluid 104 before bathtub heating system 100 begins attempting to maintain a detected temperature). Other user controls are also contemplated.
Two sheets 2105a,b may form a portion of bathtub 111 and/or may be secured to a portion of bathtub 111. In some embodiments, second sheet 2101b may be used to fuse first sheet 2101a to a side and/or bottom 2015 of bathtub 111. For example, first sheet 2101a and/or side/bottom of bathtub 111 may be fiberglass (or, for example, metal) and second sheet 2101b may be a material that may be melted (e.g., a polymer) to fuse first sheet 2101a to the side/bottom of bathtub 111. In some embodiments, second sheet 2101b may include holes to allow better contact between the wires and/or tape and the side/bottom of bathtub 111. Other layers and materials may also be used. For example, a layer of Styrofoam™ board may be used along the outside of first sheet 2105a to further insulate bathtub heating system 100.
In some embodiments, wire 2101 may be wrapped around the sides 2013a-d of bathtub 111 (e.g., through sheets 2105a,b or directly to bathtub 111) and apply heat in a range of approximately 50-60% (of total heat applied to bathtub 111) to the sides 2013a-d of bathtub 111. Other ranges are also contemplated (e.g., 70-90%). Applying the heating element over a greater surface area may increase heating uniformity and reduce hot/cold spots in bathtub fluid 104. Wire 2101 may also be applied to the bottom 2015 of bathtub 111 (e.g., applying heat in a range of approximately 40-50% (of total heat applied to bathtub 111) to the bottom 2015). Other ranges for the bottom 2015 are also contemplated (e.g., 70-90%). In some embodiments, a greater percentage of heat may be applied to bottom 2015 of bathtub 111 than to the sides of bathtub 111 to increase convective heat flow in bathtub fluid 104.
In some embodiments, wire 2101 may provide power at less than approximately 10 watts/foot. Other power density is also contemplated (e.g., greater than 10 watts/foot, in a range of 5 to 15 watts/foot, etc). In some embodiments, wire 2101 may provide a resistance approximately in a range of 1-4 ohms per foot (e.g., 2.5 ohms per foot). In an embodiment, approximately 100 feet of wire on bathtub 111 may provide approximately 1000 watts of heating (e.g., 100 feet*10 watts/foot=1000 watts). In some embodiments, bathtub fluid 104 may lose approximately 300 watts of heat to the air and approximately 700 watts through the bathtub 111 and other sources. The 1000 watts may offset this loss to hold the temperature of bathtub fluid 104 steady. Other heat loss and heat application wattages are also contemplated (e.g., the heat loss from bathtub fluid 104 may be greater in a colder environment (such as in a bathtub located outdoors in a cold environment) and, therefore, greater heat may be needed from bathtub heating system 100 to offset the heat loss). In some embodiments, heat loss may be less through the bathtub 104 (e.g., if bathtub 111 is heavily insulated, total heat loss may be approximately 300 watts). In some embodiments, the heat applied by bathtub heating system 100 may be variable to hold the temperature approximately steady. For example, bathtub heating system 100 may apply more or less heat according to a detected temperature and/or rate of temperature change (e.g., detected through temperature sensors 2005a,b). In some embodiments, more or less heat may be applied to increase or decrease the temperature (e.g., as requested through user input).
In some embodiments, wire 2101 may be continuous around the sides 2013a-d and the bottom 2015 of bathtub 111. In some embodiments, there may be two or more zones of wires (e.g., separate wires). For example, there may be one zone on the bottom 2015 of bathtub 111 and one zone around the sides 2013a-d of bathtub 111. Different levels of heating may be applied to each zone. For example, if lower temperature sensor 2005b senses a drop in temperature, a zone of heating element 2003 along the bottom 2015 of bathtub 111 may receive more energy to apply more heat to the lower portion of bathtub fluid 104. In some embodiments, wire 2101 may include series and parallel path portions on bathtub 111. As an example, approximately a 25 foot section of approximately 3/32 inch Nichrome ribbon wire (with a resistance of approximately 32.9 ohms) may generate approximately 437 watts at 120 volts and may be used with a second approximately 45 foot section of Nichrome ribbon with a resistance of approximately 67.3 ohms operating at approximately 214 watts. In another example, approximately 430 watts may be provided through approximately a 4 inch horizontal loop (e.g., formed of two strands of Nichrome ribbon) around the sides 2013a-d of bathtub 111 and approximately 213 watts on the bottom 2015 of bathtub 111 (e.g., with approximately 12 rows of Nichrome ribbon). In some embodiments, each loop around the sides 2013a-d of bathtub 111 may be a separate loop electrically coupled to control box 2009. In some embodiments, one helical loop may include several passes around the sides 2013a-d of bathtub 111.
a-b illustrate an electrical schematic of the bathtub heating system 100, according to an embodiment. It is to be noted that the values provided in
Global Variables
Uint8—operation_mode (MANUAL_MODE, NORMAL_MODE)
Uint8—operation state (STATE_OFF, STATE_MEASURE, STATE_CONTROL, STATE_COOLDOWN, STATE_TURN_OFF_DELAY, STATE_DETECT_WATER_LOSS)
Uint16—heater setpoint temp_degf×10 (target temperature)
Interrupt Service Routines
UART TX and RX (Used for debug port)
TMR0 (Used to turn on the TRIAC after a delay each half cycle of the AC)
Init Ports (This function initializes the IO ports (port direction, port input/output type, pull-ups, analog selection functions, etc.). It also places all IO into the default safe state.
Main Tasks Definitions
These functions may be called from master controller 2301 every 8.33 ms (other times are also contemplated)
Service Heater
Tasks Definitions
Service Process (This function is the high level application that controls the overall behavior. See the flowchart in
In some embodiments, a health LED (light emitting diode) may blink at approximately a 1 Hz rate (other rates are also contemplated) when the bathtub heating system 100 is not in an idle state and may be off when the bathtub heating system 100 is in the idle state. In some embodiments, the duty cycle may be 90% when heating and 10% when not heating (other duty cycles are also contemplated).
In some embodiments, a service debug port may be available. It may check to see if any new messages have been received. If they have and correspond to a valid command, that command may be executed. Example commands are provided below (other commands and command formats are also contemplated):
VER (may be used to display a firmware version and build date) (in some embodiments, may be available in auto mode);
AUTO (may be used to toggle the operation mode of the bathtub 111 between automatic and manual) (in some embodiments, may be available in auto mode);
SP=x (may be used to set the set point temperature for the heater in deg Fahrenheit (F.)×10) (in some embodiments, may not be available during auto mode);
HTRT=x (may be used to set the duty cycle value for the top heater, where x may be 0 to 120 (other values of x are also contemplated) (in some embodiments, may not be available during auto mode);
HTRT? (may be used to display the top heater duty cycle) (in some embodiments, may be available in auto mode);
HTRB=x (may be used to set the duty cycle value for the bottom heater) (in some embodiments, may not be available during auto mode);
HTRB? (may be used to display the bottom heater duty cycle) (in some embodiments, may be available in auto mode);
TEMP (may be used to toggle temperature monitoring on and off; when enabled, the sensor temperatures and heater duty cycles may be produced once per second (other times are also contemplated): top temperature degree F., bottom temperature degree F., top heater duty, bottom heater duty) (in some embodiments, may be available in auto mode);
KP=, KP? (may be used to set or display the KP parameter (e.g., in the 0-255 range)) (in some embodiments, may be available in auto mode);
KI=, KI? (may be used to set or display the Ki parameter (e.g., in the 0-255 range)) (in some embodiments, may be available in auto mode);
KD=, KD? (may be used to set or display the Kd parameter (e.g., in the 0-255 range)) (in some embodiments, may be available in auto mode);
RESET (may be used to reset the device) (in some embodiments, may be available in auto mode);
PID (may be used to display the PID information as well as the temperatures recorded by the temperature probes and the set-point temperature) (in some embodiments, may be available in auto mode);
TCTH=(may be used to set the temperature change threshold in 100ths of a degree Celsius (C.)) (in some embodiments, may be available in auto mode);
SNSR=(may be used to input false sensor readings) (in some embodiments, may not be available during auto mode).
Service Temperature Sensors
In some embodiments, this function may read two temperature sensors values (e.g., from TMP175 temperature sensors 2005), convert the read value to degrees C.×100, update the associated digital filters, update the associated global variables, and update a global flag: temperature_in_valid_range. This function may be called from master controller 2301 approximately every 50 ms (other time periods are also contemplated). The temperature sensors 2005 may use approximately 220 mS to make a 12 bit conversion, so every 5th time the Service Temperature Sensor function is called, it may read both sensors. Other configurations are also contemplated.
Service Temperature Rate Of Change
This function may calculate a rate of change for the temperature sensors 2005. It may set a flag if the rate of change is too fast. When the rate of change is too fast, this may indicate that the user has changed the temperature by adding bathtub fluid 104 to the bathtub 111.
Service Heater
This function may control the heater (e.g., wire heating elements) with phase angle firing. In some embodiments, the duty cycle may be 0-1000. In some embodiments, the heater duty cycle may be varied using a PID control algorithm that closes the loop around the measured water temperature and the water setpoint temperature.
In some embodiments, the PID algorithm may be executed and a new duty cycle may be produced at the end of each period (e.g., approximately 2.1 seconds) (other periods are also contemplated).
Heater.c and heater.h may be used for application specific functions and definitions including the Service_Heater( ) function.
In some embodiments, the heater may be turned off at every zero crossing. In some embodiments, immediately after synching to the zero crossing timer 0 may be reloaded with (65535—calculated value) so that when timer 0 overflows the TRIAC may be turned on for the requested duty cycle. In some embodiments, a 25% duty cycle may mean that the TRIAC will be turned on 25% of the time, (however, it may not equate to 25% of the power available in the AC sine wave). In some embodiments, both heaters may use the same duty cycle and may turn on at approximately the same time. They may be controlled together or independently.
At 2401, temperature at one or more temperature sensors 2005 may be detected.
At 2403, an LED (or other indicator) indicating the bathtub heating system 100 is on may not be illuminated until a temperature of the bathtub fluid 104 is detected to be above a threshold.
At 2405, the bathtub heating system 100 may monitor the temperature of the bathtub fluid 104 from one or more of the temperature sensors 2005 until the temperature is above the threshold (as long as the temperature is below the threshold, the bathtub heating system 100 may keep the LED (or other indicator) off)
At 2407, an LED may be illuminated to indicate the bathtub heating system 100 has detected a temperature change indicative of bathtub fluid 104 being added to the bathtub 111.
At 2409, the bathtub heating system 100 may wait a time period (e.g., 30 seconds). Other time periods are also contemplated.
At 2411, a determination may be made as to whether the temperature of the bathtub fluid 104 has changed by at least a specified amount (e.g., 3%, 10 degrees F., etc). If the temperature has not changed by the specified amount, the flow may return to 2407.
At 2413, if the temperature has changed by at least the specified amount, an LED (or other indicator) may be illuminated to show the bathtub heating system 100 is actively heating the bathtub fluid 104.
At 2415, a determination may be made whether the temperature of the bathtub fluid 104 is above an upper threshold (e.g., a default temperature threshold, a user specified maximum temperature threshold, etc). In some embodiments, the upper threshold may be approximately 130 degrees F. (other temperatures are also contemplated).
At 2417, if the temperature is not above the upper threshold, a determination may be made as to whether the temperature is below a lower threshold (e.g., a default temperature threshold, a user specified minimum temperature threshold, etc).
At 2419, if the temperature is not below the lower threshold, the bathtub heating system 100 may determine if the rate of temperature change is too fast (e.g., if the temperature is changing at a rate greater than a rate threshold). The rate threshold may be a default value or a user specified rate threshold (e.g., +2 to −2 degrees F in a time range of 1-2 seconds). If the temperature is changing greater than the rate threshold, flow may return to 2407 to stop or decrease applied heat until the temperature stabilizes. A temperature change greater than the rate threshold may indicate the user is adding/draining bathtub fluid 104 to adjust the temperature.
At 2421, if the temperature is not changing greater than the rate threshold, the bathtub heating system 100 may determine if there is a loss of bathtub fluid 104 (e.g., if the fluid level in the bathtub 111 has fallen below the level of a fluid level detection sensor). If fluid loss is not detected, flow may return to 2413 to continue applying heat to the bathtub fluid 104.
At 2423, if fluid loss is detected, the bathtub heating system 100 may stop or reduce heat applied and may indicate (e.g., through an LED) that heat has been stopped or reduced. In some embodiments, the bathtub heating system 100 may indicate that the fluid level is below a certain level.
At 2425, the bathtub heating system 100 may monitor a temperature of the bathtub fluid 104, and if the rate of temperature change of the bathtub fluid 104 is above a specified rate (e.g., approximately +5 to −5 degrees F. in a time range of approximately 1-2 seconds, or, for example, greater than approximately 5% in approximately 1-2 seconds), the flow may return to 2417 to determine if the temperature of the bathtub fluid 104 is below a lower threshold.
At 2427, (from 2415) if the temperature is above the upper threshold, the bathtub heating system 100 may stop applying heat or may apply less heat to the bathtub fluid 104. In some embodiments, the bathtub heating system 100 may indicate (e.g., through an LED) that the bathtub heating system 100 has stopped or decreased heating.
At 2429, another determination may be made as to whether the temperature of the bathtub fluid 104 is above the upper threshold. If the temperature is above the upper threshold, flow may return to 2427 to continue not applying heat (or reducing the amount of heat applied).
At 2431, (from 2417) if the temperature is below the lower threshold (e.g., approximately 90 degrees F.) or (from 2429) if the temperature is not above the upper threshold, the bathtub heating system 100 may stop applying heat or may apply less heat to the bathtub fluid 104. In some embodiments, the bathtub heating system 100 may indicate (e.g., through an LED) that the bathtub heating system 100 has stopped or decreased heating. In some embodiments, the temperature may have fallen below the lower threshold if the bathtub fluid 104 was drained below the level of one of the temperature sensors 2005 (such that the temperature sensor (e.g., temperature sensor 2005a) is detecting the temperature of the air). The heating applied may be decreased or stop to avoid excessive heat buildup on the bathtub surface.
At 2433, a time period may elapse (e.g., approximately 5 minutes). After the time period (which may be a default value, user specified value, etc.) elapses, flow may return to 2403. Until the time period elapses, flow may continue at 2431.
At 2501, a bathtub may be provided that is configured to hold a bathtub fluid. The bathtub may include bottom and side walls (each with an interior and exterior surface).
At 2503, a heating element may be coupled to the bathtub. The heating element may be positioned 1) proximate to the exterior surface of at least one of the bottom and/or side walls and/or 2) within at least one of the bottom and/or side walls. The heating element may be integrated into the walls or attached through a clip, adhesive, etc.
At 2505, a fluid level sensor may be coupled to the bathtub to detect a presence of a fluid within the bathtub. The heating element may be configured to heat the bottom and/or side walls of the bathtub to heat the bathtub fluid within the bathtub when the fluid level sensor detects a presence of a fluid within the bathtub.
Embodiments of a subset or all (and portions or all) of the above may be implemented by program instructions stored in a memory medium or carrier medium and executed by a processor (e.g., processors 1401). A memory medium may include any of various types of memory devices or storage devices. The term “memory medium” is intended to include an installation medium, e.g., a Compact Disc Read Only Memory (CD-ROM), floppy disks, or tape device; a computer system memory or random access memory such as Dynamic Random Access Memory (DRAM), Double Data Rate Random Access Memory (DDR RAM), Static Random Access Memory (SRAM), Extended Data Out Random Access Memory (EDO RAM), Rambus Random Access Memory (RAM), etc.; or a non-volatile memory such as a magnetic media, e.g., a hard drive, or optical storage. The memory medium may comprise other types of memory as well, or combinations thereof. In addition, the memory medium may be located in a first computer in which the programs are executed, or may be located in a second different computer that connects to the first computer over a network, such as the Internet. In the latter instance, the second computer may provide program instructions to the first computer for execution. The term “memory medium” may include two or more memory mediums that may reside in different locations, e.g., in different computers that are connected over a network.
In some embodiments, a computer system at a respective participant location may include a memory medium(s) on which one or more computer programs or software components according to one embodiment of the present invention may be stored. For example, the memory medium may store one or more programs that are executable to perform the methods described herein. The memory medium may also store operating system software, as well as other software for operation of the computer system.
Further modifications and alternative embodiments of various aspects of the invention may be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the general manner of carrying out the invention. It is to be understood that the forms of the invention shown and described herein are to be taken as embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features of the invention may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description of the invention. Changes may be made in the elements described herein without departing from the spirit and scope of the invention as described in the following claims.
This application claims the benefit of priority of U.S. Provisional Patent Application Ser. No. 60/988,959 titled “Systems and Methods for Bathtub Heating”, filed on Nov. 19, 2007, whose inventors are Michael Lee Kenoyer and Richard Gene Washington, which is hereby incorporated by reference in its entirety as though fully and completely set forth herein.
Number | Date | Country | |
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60988959 | Nov 2007 | US |