Abstract:
A current sensing switch for use with a pump that is physically separate from the pump and contains a current sensor for measuring the electrical current flowing to the pump as a method of determining whether the pump is operating in low fluid, dry conditions, or with an impeller that has ceased to rotate. When the current drops below or raises above a predetermined value for a predetermined amount of time, the switch electrically disconnects power to the pump and reconnects it periodically to cheek whether the state of the pump has changed.

Description:
[0001]    This document claims priority to and is a continuation-in-part to U.S. patent application Ser. No. 14/667,690 filed on Mar. 25, 2015. 
     
    
     BACKGROUND OF INVENTION 
       [0002]    Field of Invention 
         [0003]    The present invention concerns a switch for use with a pump that prevents the pump from operating in low fluid or dry conditions. 
         [0004]    Description of Prior Art 
         [0005]    Pumps are the item of choice to remove fluid out from places such as flooded basements, window wells, and swimming pool covers. Pumps are also used in areas where fluid needs to be recirculated. Pumps are typically activated by the push of an electrical switch that is turned on when the pump is submerged in the fluid that needs to be removed or circulated. The pump then sucks the fluid in through a fluid inlet and pushes the fluid out through a fluid outlet to which a hose or pipe is attached that directs the fluid to the desired location. 
         [0006]    A problem occurs if the pump is left activated in a condition in which fluid is not present. For example, a pump can be used to pump out fluid in a flooded basement. But once the fluid in the basement has been pumped out, the user often neglects to turn off the pump for an extended period of time. In essence, activating a pump while not submersed in fluid can lead to substantial overheating and damage to the pump motor. To resolve this problem, some pumps include a motor that is sealed in oil with an automatic thermal overload protector device. Thus, when the pump is left activated and not submerged in fluid, the motor begins to overheat and the thermal overload protector device is triggered to deactivate the pump automatically. 
         [0007]    Other pumps utilize a pressure switch to measure the fluid pressure around the pump. When the pressure switch does not detect any fluid pressure, it deactivates the pump under the presumption that the pump is not submerged in fluid. Furthermore, as taught by U.S. Pat. No. 4,276,454, coated fluid repellant probes have been used to detect whether the pump is submerged in fluid. U.S. Pat. No. 4,881,873 teaches the use of an ultrasonic field detection system. U.S. Pat. No. 4,897,822, teaches the use of acoustic transducers. U.S. Pat. No. 5,425,624, teaches the use of optical fibers. Thus, a wide range of technologies have been used to address this problem of making sure a pump is not left activated while it is not submerged in fluid or in dry conditions. 
         [0008]    Yet other pumps used a control circuit for turning off the power to the pump drive motor when the average current draw from the pump motor decreases below a preset level. This method of measuring the current has proven effective because the current through the pump motor is proportional to the work being done by the pump. Thus, measuring the current can allow a system determine whether the pump is actually pumping fluid or just spinning in air. This concept of measuring the current is taught by U.S. Pat. No. 3,953,777; U.S. Patent Application No. 2013/0140912; and European Patent Application No. EP 2 439 413. 
         [0009]    The problem with these devices is that they are electrically and/or physically connected to a pump and cannot be deactivated or adjusted to accommodate varying conditions. Furthermore, current sensing circuitry is typically built into a specific pump for ease of manufacturing. However, when the circuitry fails, the entire pump becomes unusable. 
         [0010]    To address the deficiencies of the inventions mentioned above, what is needed is a device that can not only be electrically disconnected from a pump but can measure the current flow to the pump motor so that it deactivates the pump when the current falls below a predetermined level. Furthermore, a device is needed that can be used with pumps of varying sizes and power. Even further, a device is needed with a current sensing, circuitry that can disconnect or deactivate a pump completely so as to prevent the pump from running in low fluid or dry conditions. 
       SUMMARY OF THE INVENTION 
       [0011]    Accordingly, the present invention has been made in view of the above-mentioned disadvantages occurring in the prior art. The present invention is a pump switch with a current sensing circuitry that prevent a pump from operating in low fluid, dry conditions, or with a blocked impeller. 
         [0012]    It is therefore a primary object of the present invention to measure the current being fed into the pump as a way to measure the work being done by the pump. 
         [0013]    Another object of the present invention is to provide a pump switch that is not built-in or incorporated in a pump. 
         [0014]    Yet another object of the present invention to provide a pump switch that can detect false readings. 
         [0015]    The above objects and other features and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention, are described in detail below with reference to the accompanying drawings. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0016]    The accompanying drawings which are incorporated by reference herein and form part of the specification, illustrate various embodiments of the present invention and together with the description, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention. In the drawings, like reference numbers indicate identical or functional similar elements. A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: 
           [0017]      FIG. 1  is a front perspective view of the pump switch of the present invention. 
           [0018]      FIG. 2  is a front view of the pump switch of the present invention. 
           [0019]      FIG. 3  is a side view of the pump switch of the present invention. 
           [0020]      FIG. 4  is an exploded view of the pump switch of the present invention. 
           [0021]      FIG. 5  is a diagram depicting the pump switch of the present invention connected to a pump. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0022]    Reference will now be made to the drawings in which various elements of the present invention will be given numerical designations and in which the invention will be discussed so as to enable one skilled, in the art and make use the invention. 
         [0023]    The present invention comprises a pump switch  100  with a housing  10  having prongs  20  of an electrical, plug extending therefrom and an electrical plug socket  30 . Inside the housing  10  is a circuit board  40  having a relay that is capable of electrically connecting and disconnecting the electrical plug socket  30  to the prongs  20  of the electrical plug. The circuit board  40  comprises a current sensor, a data center, a controller, a power switch  43 , and a current setting switch  44 . 
         [0024]    Application of the present invention is with pumps  200 . As shown in  FIG. 5 , a pump  200  has an electrical cord  210  extending therefrom with an electrical plug  215  at the end. The electrical plug  215  is generally plugged in to an electrical plug socket through which electrical current is passed to power up and activate the pump  200 . When the pump  200  is activated, a pump motor activates to drive an impeller. When the pump  200  is submerged in fluid, for example, the rotation of the impeller causes the fluid to flow such that the fluid is sucked in through the inlet  230  and pushed out of the outlet  235  of the pump  200 . 
         [0025]    However, a problem arises when the pump  200  is not submerged in fluid or when the impeller ceases to rotate. This can occur when the pump  200  has finished pumping out the fluid in which it was submerged or when the impeller is blocked. When the pump  200  operates and is not submerged in fluid or the impeller is blocked, the pump motor can overheat and be permanently damaged. 
         [0026]    The present invention addresses this problem by electrically connecting the circuit board  40  in-line with the electrical plug socket, thus, the power source. Therefore, rather than connecting the electrical plug  215  directly to the electrical plug socket, the plug  215  is connected to the electrical plug socket  30  in the pump switch  100  of the present invention. The prongs  20  of the electrical plug in the pump switch  100  of the present invention is then connected to the electrical plug socket to which the plug  215  would normally be connected. 
         [0027]    The current sensor  41  of the circuit board  40  measures the electrical current passing from the pump switch  100  of the present invention to the pump  200  through the plug  215 . This is measured because the electrical current passing to the pump  200  is proportional to the work being done by the pump  200 . Thus, measuring the electrical current can allow the pump switch  100  determine whether the pump is actually pumping fluid, just spinning in air, or if the impeller is stuck. 
         [0028]    The current setting switch  44  is used to set a lower electrical current limit or a lower current setting value for the pump switch  100 . Thus, if the electrical current passing to the pump  200 , as measured by the current sensor  41 , fails below the lower current setting value, then the pump switch  100  terminates the electrical current flow to the pump  200  by electrically disconnecting the pump  200  from the power source. As shown in  FIG. 3 , in the preferred embodiment of the present invention, the current setting switch  44  is a dial switch that can be rotated to vary or change the lower current setting value. The current setting switch  44  is readily accessible by the user to vary or change the lower current setting value. Thus, the pump switch  100  of the present invention can be utilized with different types of pumps and fluids of varying viscosity and other characteristics. Depending on the type of pump and type of fluid used, the user can readily change the lower current setting value using the current setting switch  44  to maintain said pump switch.  100  within an acceptable operating range. Although the preferred embodiment of the present invention utilizes a dial switch for the current setting switch  44 , it is understood that the current setting switch  44  can be a digital switch, a push button switch, a keypad, and the like. 
         [0029]    When the user sets the current setting switch  44  to a particular setting, the digital value of the lower current setting value is transmitted and stored within the data center in the circuit board  40 . The controller then calculates an upper current setting value based on the lower current setting value and the average electrical current passing to the pump  200  within a predetermined time period as measured by the current sensor  41 . Then the digital value of the electrical current passing to the pump  200  is periodically transmitted to the data center and compared with the lower and upper current setting values, lithe electrical current is less than the lower current setting value or higher than the upper current setting value, then the pump switch  100  disconnects the pump  200  from the power source, thus, terminating the flow of current to the pump  200 . The connecting and disconnecting of the pump  200  from the power source is accomplished by the relay by electrically connecting or disconnecting the electrical plug socket to the prongs. 
         [0030]    However, to avoid false readings, the pump switch  100  of the present invention incorporates a delay of a few predetermined seconds. Thus, when the electrical current drops below the lower current setting value or rises above the upper current setting value, the pump switch  100  waits for the few predetermined seconds before disconnecting the pump  200  from the power source. If the electrical current is below or above the lower or upper current setting values for the duration of the few predetermined seconds, then the pump switch  100  disconnects the pump  200  from the power source. This delay allows the pump switch  100  to distinguish between a change in the electrical current caused by actual work done by the pump  200  or by a change caused by other circumstances. 
         [0031]    If the pump  200  is disconnected by the pump switch  100  due to a drop in the electrical current below the lower current setting value, then the pump  200  remains disconnected for a first predetermined time period after which the pump switch  100  reconnects the pump  200  and recalculates whether the electrical current is still below the lower current setting value for the few predetermined seconds. If so, then the pump  200  is again disconnected by the pump switch  100  for the first predetermined time period after which the pump switch  100  repeats the cycle. This cycle is repeated by the pump switch  100  every first predetermined time period until, the electrical current, as measured by the current sensor  41 , is higher than the lower current setting value or until the pump switch  100  is disconnected from its power supply. The repetition of this cycle is an important aspect of the pump switch  100  of the present invention as it ensures that that pump  200  pumps out all of the intended water or fluid. For example, in a situation where a basement of a house is being flooded by water from a faulty plumbing pipe or rain, the rate of water pumped out of the basement by the pump  200  may be greater than the rate of water leaking or flowing into the basement. Thus, at a certain point, all or most of the water may be pumped out of the basement by the pump  200 . Thus, it is preferred that the pump  200  be turned off or deactivated. However, the water may not have stopped from leaking or flowing into the basement, the water may flow into the basement at a lower rate than the pump  200  can pump it out of the basement. Thus, if the pump  200  is turned, off or disconnected indefinitely, then the water will continue to flood the basement during the indefinite time that the pump is left inoperable. Accordingly, the pump switch  100  of the present invention, periodically turn on the pump  200  to compare the electrical current to the lower current setting value so as to check whether any water or fluid has returned. In the preferred embodiment of the present invention, the pump switch  100  powers up the pump  200  periodically after every first predetermined time period, which can be between 5 to 10 minutes. The connecting and disconnecting of the pump  200  from the power source is accomplished by the relay by electrically connecting or disconnecting the electrical plug socket to the prongs. 
         [0032]    Similarly, circumstances may arise in which the inlet  230  of the pump  200  is blocked so as to prevent any water from entering the pump  200  and creating a vacuum therewithin. Alternatively, the impeller of the pump  200  may be physically blocked or trapped. In both scenarios, the impeller may cease its rotation causing the electrical current to spike or rise above the upper current setting value. Allowing the pump  200  to operate when the impeller is trapped or ceases its rotation can cause substantial overheating and damage to the pump  200 . As such, the pump switch  100  of the present invention terminates the current flow to the pump  200  when the electrical current passing from the pump switch  100  to the pump  200  is greater than the upper current setting value for the duration of the few predetermined seconds. 
         [0033]    If the pump  200  is disconnected by the pump switch  100  due to an increase in the electrical current above the upper current setting value, then the pump  200  remains disconnected for a second predetermined time period after which the pump switch  100  reconnects the pump  200  and recalculates whether the electrical current is still above the upper current setting value for the few predetermined seconds. If so, then the pump  200  is again disconnected by the pump switch  100  for the second predetermined time period after which the pump switch  100  repeats the cycle. This cycle is repeated by the pump switch  100  every second predetermined time period until the electrical current, as measured by the current sensor  41 , is lower than the upper current setting value or until the pump switch  100  is disconnected from its power supply. The repetition of this cycle is an important aspect of the pump switch  100  of the present invention as it ensures that the pump  200  pumps out all of the intended water or fluid. For example, in situations when the impeller is blocked, the water may continue to flood a basement. Thus, if the pump  200  is turned off or disconnected indefinitely, then the water may continue to flood the basement even if the impeller is unblocked at a later time. Accordingly, the pump switch  100  of the present invention, periodically turns on the pump  200  to compare the electrical current to the upper current setting value so as to check whether the impeller is still blocked. In the preferred embodiment of the present invention, the pump switch  100  powers up the pump  200  periodically after every second predetermined time period, which can be once or twice per day. The connecting and disconnecting of the pump  200  from the power source is accomplished by the relay by electrically connecting or disconnecting the electrical plug socket to the prongs. 
         [0034]    The housing  10  of the pump switch  100  comprises a first half  11  and a second half  12  that attach together with the circuit board  40  in between, as shown in  FIG. 4 . The housing  10  would provide weatherproofing of the pump switch  100  by the manner in which it encloses the circuit board  40  therewithin. The housing  10  would incorporate an o-ring or gasket in between said first half  11  and said second half  12  to protect the circuit board  40  from fluid exposure. Furthermore, a radial seal  13  would be used in the current setting switch  44  to further protect the circuit board  40  from fluid exposure. Finally, the power switch  43  would be encapsulated within a flexible thermoplastic protector to even further protect the circuit board  40  from fluid exposure. 
         [0035]    It is understood that the described embodiments of the present invention are illustrative only, and that modifications thereof ma occur to those skilled in the art. Accordingly, this invention is not to be regarded as limited to the embodiments disclosed, but to be limited only as defined by the appended claims herein.