A liquid level detection and control system having a shut off gate located near the liquid discharge outlet and a liquid level sensor which sends signal to a wireless transmitter when a preset liquid level is detected. The transmitter then transmits signal to an electronic receiver and from there to an electronic circuit which transmit signal to a solenoid operatively associated with the shut off gate to open and close the gate.

FIELD OF THE INVENTION  
       [0001]     This invention relates to liquid level control system and is particularly related to an automatic liquid level control system for bathtubs, sinks or other similar containers to prevent liquid overflow and assure safety.  
       BACKGROUND OF THE INVENTION  
       [0002]     Various liquid level control devices and systems have been described in the prior art and widely used in different households, hotels and other institutions. Some of these systems sound an alarm signal when the liquid reaches a certain level while other systems operate on mechanical liquid level relief principles. Regardless of the control mode, the purpose is to assure safety of the person in a bathtub by alerting such person of the safety level of the liquid, and prevent damage to the floor which may result from liquid overflow.  
         [0003]     One bath water level control system is described in U.S. Pat. No. 4,258,444 issued to Wily Orszullok on Mar. 31, 1981. That system is designed for exterior installation relative to the bathtubs and includes a probe or detecting means which is vertically adjustable on the exterior wall of the tub. When the water reaches a predetermined level, the probe emits a signal which activates a device to turn off the inflowing water and/or trip an alarm.  
         [0004]     U.S. Pat. No. 6,008,728 issued to Akintunde O. Wesley on Dec. 28, 1999 describes a water level detection and alarm device used for bathtubs. The device comprises a housing which is secured to the interior surface of the tub and includes a float and water level alarm system which sounds an alarm when the water level in the tub reaches a predetermined level.  
         [0005]     A tub alarm apparatus is described in U.S. Pat. No. 6,160,482 issued to Timothy W. Hill on Dec. 12, 2000. The alarm apparatus described therein includes a suction cup for secured to the wall of the bathtub. An alarm housing is attached to the top of the suction cup and an alarm system is located within the alarm housing. A float is supported by the alarm housing for activating the alarm when the water in the bathtub reaches a predetermined level.  
         [0006]     U.S. Pat. No. 6,480,113 B1 issued to David W. Esposito on Nov. 12, 2002 describes a water level alarm system which comprises a housing, a float, a battery compartment, a speaker and an alarm. The housing is secured to the sides of the water container and the float rises with the water and when it reaches a certain level it makes contact with two separate conductors to complete a circuit and sound an alarm.  
         [0007]     Thus, even though there are several prior art systems in use for controlling liquid levels in containers, most commonly in bathtubs, such systems are generally complicated to install and/or difficult to construct and operate.  
         [0008]     It is therefore an object of the present invention to provide a liquid level alarm system which is simple to construct, install and operate.  
         [0009]     It is another object of this invention to provide a water level control system for bathtubs which is capable of signaling when the water level in the bathtub reaches a certain predetermined level thus alerting the user to shut-off the flow of water into the tub.  
         [0010]     It is also an object of the present invention to provide an automatic liquid level detection system for bathtubs and similar containers, which interrupts or reverses the inflow of water automatically when it reaches a predetermined unsafe or undesirable level in the bathtub or the container.  
         [0011]     Other features of the present invention will be more fully comprehended and appreciated from the ensuing detailed description which must be read in conjunction with the accompanying drawings.  
       SUMMARY OF THE INVENTION  
       [0012]     The present invention provides a liquid level detection and control system for controlling the liquid level in a bathtub when it reaches a preset level. The system comprises a shut off gate which is hingedly positioned near the liquid discharge outlet, and a sensor which is capable of detecting the liquid level when it reaches said preset level. When the sensor detects the liquid level, it transmits electronic signal to a wireless signal transmitter which, in turn, transmits wireless electronic signal to a receiver. The receiver will then transmit wireless electronic signal to an electronic circuit which transmits the signal to a solenoid valve which is operatively associated with a shut off gate and closes the gate to prevent liquid from rising above the preset liquid level. By closing the water supply faucet, the water level drops, the shut off gate will drop to the open position and water will flow into the tub.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     In the drawings, wherein like reference numerals are used to designate like parts where possible;  
         [0014]      FIG. 1  is a schematic diagram showing the present invention used in a bathtub;  
         [0015]      FIG. 2  is a block diagram showing the different components of the system of this invention and the inter-relationship of the components; and  
         [0016]      FIG. 3  is another block diagram which shows different modes of operation of the system of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0017]     Referring now to the drawings, there is shown in  FIG. 1 a  bathtub  11  equipped with a faucet handle  13  and a main housing  15  mounted thereon. The main housing  15  comprises a hinged shutoff gate  17  having a seep hole  19 , disposed in the liquid inflow path indicated by the arrows A, and an indicator light  20 . Ordinarily in residential and commercial bathtubs, the bathtubs are provided with an overflow drain in order to facilitate overflow of water out of the bathtub but sometimes due to malfunction of the drain, water may not be discharged rapidly through the drain thus causing overflow and damage to the surrounding floor. The present device is designed to prevent overflow because when the water level in the tub reaches a preset level, the water stops flowing out through the faucet  21  which is mounted on the main housing, as indicated by the arrows B. This insures that water in the tub will not overflow when it reaches such level as will hereinafter been described. The system of the present invention also comprises a sensor housing  23  which is secured to the faucet  21  and is capable of interacting with the main housing  15  to control the water flow into the tub  11 .  
         [0018]     Referring to  FIG. 2 , it can be seen that the sensor housing  23  comprises a battery  25 , a waterflow sensor  27 , signal transmitter, e.g., a wireless signal transmitter  29  and liquid level sensor  31 . The main housing  15  comprises a signal receiver, e.g., a wireless signal receiver  33  which receives electrical signals from the wireless transmitter  29 , a battery  35 , an electronic control circuit  37  which receives signals from the wireless receiver  33  and activates a solenoid actuator  39 .  
         [0019]     The liquid level sensor  31  in the sensor housing  23  generates an output signal to the wireless signal transmitter  29  when the water in the tub reaches a preset level. The wireless signal transmitter  29  then transmits an electrical signal to the wireless signal receiver  33  located in the main housing  15 . The signal from the receiver  33  is then transmitted to the electronic control circuit  37  which serves to activate the solenoid actuator (valve)  39 . The electronic control circuit  37  is capable of activating the devices within the electronic circuit  39  by audible and/or visible signals. The solenoid actuator  39  serves to open or close the hinged shut off gate  17  which is hinged at  18 . Thus, when the solenoid actuator is in the inactive status (not receiving any signal) liquid is flowing into the bathtub and the shut off gate  17  is in open position  17 A but once it receives a signal from the electronic circuit  37  in response to signal from the sensor  31 , it changes to active mode, thus indicating that the flow of water has ceased and the shut off gate  17  is in closed position  17 B, as shown in  FIG. 1 . Both the main housing and the sensor housing include a battery such as battery  25  and battery  35  to provide the source of electrical power to the electronic components of the system.  
         [0020]     The system of the present invention can basically exist in three modes, i.e., (A) standby mode, (B) monitor mode, and (C) activated mode. In the standby mode (A), there is no liquid flowing through the system, no power is applied to the sensor  31  no power is used in the main housing  15 , and the hinged shut off gate  17  is in open position. In the monitor mode (B) water flows through the faucet, the water flow sensor  27  detects flow, and power is applied to the sensor  31  so that the sensor can detect when the liquid level reaches the preset danger level. No power is used in the main housing  15  and the hinged shut off gate is in its open position. In the activated mode (C), very little liquid flows through the system, no power is applied to the main housing circuitry and the hinged shut off gate is in closed position.  
         [0021]     In order to change from one mode of operation to another mode, reference may be had to  FIG. 3  in the drawings. This figure describes the actions which must take place for transition from one mode to another. In the standby mode (Mode A) as shown by  41  in  FIG. 3 , no power is applied to the sensor, the water level is not being monitored, the shut off gate  17  is in open position  17 A due to water seeping through a seep hole  19  located conveniently in the middle of the shut off gate  17 . In the first action, action no.  1 , see  43  in  FIG. 3 , liquid pressure is applied by opening the faucet  13  thus causing the flow of liquid through the system. In the next mode (Mode B) power is applied to the sensor  31 , the water level in the bathtub  11  is monitored until it reaches the preset danger level. At this point the solenoid valve  39  is actuated which causes the shut off gate  17  to flip into closed position  17 B. In the second action, i.e., Action  2  (see  47  in  FIG. 3 ), liquid flow is stopped since the shut off gate  17  is closed. In the next mode (Mode C, see  49  in  FIG. 3 ), power to the sensor  31  is cut off, the water level in bathtub  11  stops rising, the solenoid valve  39  is momentarily actuated and the shut off gate  17  flips to the closed position. In the next and third action, i.e., Action No.  3 , see  51  in  FIG. 3 , the faucet is closed, water pressure drops slowly due to a few drops of water seeping through the seep hole  19  and the shut off gate will slowly drop from position  17 B (closed) to position  17 A (open). The system thus changes from Mode C to Mode A as shown in  FIG. 3 . An indicator light  20  in the main housing  15  provides a signal indicating low battery in the housing.  
         [0022]     Thus, as it can be seen, the system described herein provides an efficient and practical system for installation in bathtubs, sinks and the like to control the liquid level at a preset level without the disadvantages of the prior art devices. It can also be appreciated that from the present description one skilled in the art may make several modifications or changes in the system without departing from the scope of this invention.