Abstract:
A fluid level detection device comprising an elongated shaft having a plurality of sensors and associated switches on a distal end thereof. The distal end of the shaft extends into a liquid reservoir with the switches configured to detect multiple predetermined fluid levels. The first fluid level detected is a warning level indicating that the level of fluid in the reservoir is low and results in a warning indication. The second fluid level detected is for a shutoff threshold that results in shutdown of the device using the fluid in the reservoir and a shutdown indicator.

Description:
This application claims the benefit of U.S. Provisional Application No. 61/817,024, filed on Apr. 29, 2013. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to a system and apparatus for detecting the level of fluid in a reservoir. More specifically, this invention is directed to a fluid reservoir level detection system designed to detect fluid loss and prevent component failure from loss of fluid and the possibility of a hazmat situation. 
     There are many devices known in the art for detecting the level of fluid in a reservoir. Such known devices typically comprise a single float or bobber that encloses an air pocket or is otherwise of a lower density than the fluid in the reservoir. The float or bobber is typically disposed at or near the end of a vertically disposed shaft or a horizontally disposed arm. When the level of fluid in the reservoir is above a certain threshold the float or bobber is forced upwards so as to either rise up the vertical shaft or rotate the horizontally disposed arm about a pivoting connection. When the float has risen up the shaft or caused the level arm to rotate upward, a circuit is typically opened so that a sensor light or other alert is off or otherwise not triggered. As the level of fluid in the reservoir decreases, the float drops with the level of the fluid. When the level reaches a certain threshold, the float is lowered to the point where a switch is activated and a circuit closes so as to activate a sensor light or other alert mechanism. 
     Typically these systems provide only one alert level and are only configured to notify a person that the fluid level is low. Such prior art devices are not configured to detect a second level threshold or otherwise provide a second alert or take corrective action. 
     Accordingly, there is a need for a fluid reservoir level detection system that detects two or more level thresholds and provides alerts or initiates a cutoff as a designated threshold is reached. Furthermore, there is a need for such a system that can disable or deactivate machines relying upon the fluid in the reservoir when a critical level threshold is reached. Such a system would provide users with more informed knowledge of the fluid level in closed or not easily accessible reservoirs and prevent component failure from loss of fluid. The present invention fulfills these needs and provides other related advantages. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a fluid level detection device and system. The device comprises an elongated shaft having proximal and distal ends. An upper sensor and lower sensor are both independently disposed on the distal end of the shaft. A first switch is fixedly disposed within the distal end of the shaft proximate to and responsive to the upper sensor. A second switch is fixedly disposed within the distal end of the shaft proximate to and responsive to the lower sensor. A multi-wire conductor having a wire connector extends from the proximal end of the shaft with the multi-wire conductor being electrically coupled to the first and second switches. The upper and lower sensors preferably comprise upper and lower floats slidingly disposed on the distal end of the shaft, wherein both of the upper and lower floats are buoyant in a fluid. Where the sensors are floats, the device includes an upper locking spacer on the shaft above the upper float, a lower locking spacer on the shaft below the lower float, and a middle locking spacer on the shaft between the upper float and the lower float. 
     A fluid level detection system comprises a fluid level detection device as described above. The proximal end of the shaft is sealingly affixed to an exterior surface of a fluid reservoir and the distal end extends into the fluid reservoir. A power supply is electrically connected to both of the first switch and the second switch through the multi-wire conductor. A low level indicator is electrically connected to the first switch. A system relay has a power input from the power supply, a control input from the second switch, an operation output to a device controller, and an indicator output to a shutdown indicator. 
     In the system, the first switch is in an open position when the upper sensor detects the fluid above a warning threshold and in a closed position when the upper sensor does not detect the fluid above the warning threshold. The low level indicator is in an off state when the first switch is in the open position and in an on state when the first switch is in the closed position. 
     The second switch is in a closed position when the lower sensor detects the fluid above a shutdown threshold and in an open position when the lower sensor does not detect the fluid above the shutdown threshold. The system relay electrically connects the second switch to the operation output and the device controller when the second switch is in the closed position. The indicator output and shutdown indicator are electrically disconnected from both the second switch and the power source when the second switch is in the closed position. The system relay electrically connects the power source to the indicator output and shutdown indicator when the second switch is in the open position. The operation output and the device controller are electrically disconnected from both the second switch and the power source when the second switch is in the open position. 
     The system further comprises an override switch electrically connected to the device controller, wherein the override switch connects the device controller to an alternate power source when the override switch is in a closed position. 
     The fluid level detection device comprises an elongated shaft having a proximal end and a distal end, wherein the proximal end of said shaft is sealingly affixed to an exterior surface of a reservoir and the distal end extends into the fluid reservoir, the distal end having an upper sensor and a lower sensor configured to detect a level of fluid in the reservoir, a first switch contained within the distal end and responsive to the upper sensor, a second switch contained within the distal end and responsive to the lower sensor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings illustrate the invention. In such drawings: 
         FIG. 1  is a photograph of a device designed to implement the reservoir fluid level detection system of the present invention; 
         FIG. 2  is an illustration of the inventive fluid level sensing device installed in a fluid reservoir; 
         FIG. 3  is an illustration of a control panel cover for the reservoir fluid level detection system of the present invention; and 
         FIG. 4  is a schematic illustration of the electrical wiring and sensors of the reservoir fluid level detection system of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention is directed to a reservoir fluid level detection system and device. The system and device may be used with any fluid reservoir in which the fluid may be consumed, lost or otherwise removed from the reservoir, in which the quantity of fluid must be maintained or replaced in order to continue operating a particular machine, engine or similar apparatus. The inventive device is designed to detect, prevent and minimize fluid loss in case of, as a result of, or to prevent component failure. Using a floating switch that is adjustable in height with multiple floats placed on a common stock and able to accommodate any type of fluid allows for the provision of multiple fluid level warnings and disengagement or stoppage of any device that may rely upon the fluid for operation or be a source of fluid leakage. 
     The individual floats are configured such that the top floats are wired for normally closed operation, e.g., fail to close, and provide power for warning lights and/or audible alarms upon such closure. The bottommost float is configured to be wired for normally open operation, e.g., fail to open, and is used to signal a relay, of any given voltage, which in turn shuts off any component drawing from the fluid in the reservoir. The component drawing from the fluid in the reservoir can be anything from a power take-off (PTO) driven hydraulic pump to an auxiliary engine, or even a stationary fluid pumping station. The reservoir fluid level detection device can trip any voltage and control any type of device, e.g., pneumatic, hydraulic or electric. The system has an override in case any part of the device may have to be moved in order to facilitate transport or repairs. 
     With concerns of hazardous material spillage at an all-time high and its effects on the environment, this device can minimize the impact of hazardous material fluid loss and possibly even stop it before suffering catastrophic consequences. 
     The present invention is directed to a fluid level detection device and system that uses at least two fluid level sensors disposed on an elongated shaft, which shaft extends into a reservoir so as to place the fluid level sensors in contact with a fluid contained within the reservoir. The sensors are configured to detect the level of fluid contained within the reservoir relative to both a warning threshold and a shutdown threshold. The fluid level sensors may comprise any type commonly used in the art, including pneumatic, conductive, or magnetic/mechanical floats. The choice of which type of sensor is used depends upon factors such as cost, type of fluid (i.e., corrosive, hazardous, etc.), or environment. The following description will focus on float-type sensors, but the aims of the invention can be met with any type of fluid level sensor. 
       FIG. 1  is an illustration of a particularly preferred embodiment of the reservoir fluid level detection device  10  of the present invention. The device  10  comprises an elongated shaft  12  having a threaded coupling  14  at its proximate end  16 . As shown in  FIG. 2 , the threaded coupling  14  is configured to secure the device  10  into the lid or other top of a reservoir  18  such that the shaft  12  extends vertically downward toward the bottom of the reservoir  18 . The length of the shaft  12  is configured such that its distal end  20  is disposed just below usable fluid levels in the reservoir  18 . The length of the shaft  12  is preferably adjustable to variably and more precisely place the distal end  20  in the reservoir  18  relative to fluid levels. The methods of adjustment will be described further below. 
     The distal end  20  of the shaft  12  has at least two floats  22 ,  24  configured to be slidable along a portion of the shaft  12 . The first float  22  is preferably disposed above the second float  24 . A person skilled in the art will realize that more than two floats may be used to activate multiple level sensors. However, the following description will focus on only the uppermost float  22  and the bottommost float  24 . 
     The floats  22 ,  24  are in communication with switches disposed inside the shaft  12 . Such communication is preferably a wireless, near field communication, e.g., electric or magnetic, so that the shaft  12  may be a closed system to prevent intrusion of the fluid  26  into the interior of the shaft  12 . This allows for the device  10  to be used with hazardous or corrosive materials. 
     The floats  22 ,  24  are preferably restricted in their movement along the shaft by locking spacers  28  disposed on the shaft  12  both above and below each of the floats  22 ,  24 . A multi-wire conductor  30  extends from the proximate end  16  of the shaft  12  through the threaded coupling  14 . The multi-wire conductor  30  is electrically connected to a plurality of switches (not shown here) on the interior of the shaft  12  corresponding to the number of floats  22 ,  24 . The other end of the multi-wire conductor  30  runs to a connector  32  that is configured to electrically connect the wire  30  to a remote or proximate control panel  34 . 
     One method for adjusting the length of the shaft  12  is by way of the coupling  14 . The coupling  14  may be slidable along the shaft  12  and have a compression or other locking feature such that it will hold the shaft  12  at a fixed depth within the reservoir  18  when the coupling  14  is secured. Other types of couplings  14  may be used to accomplish similar functionality. Another method to adjust the length of the shaft  12  is to make the position of the floats  22 ,  24 , locking spacers  28 , and switches  42 ,  44  variable along and within the shaft  12 . 
     As shown in  FIG. 3 , the control panel  34  includes a low fluid alert light  36  and a stop alert light  38 . The control panel  34  also includes an override button  40 . The operation of these lights and buttons will be described more fully below. 
     When the level of fluid  26  in the reservoir  18  is above both floats  22 ,  24 , the uppermost float  22  rises up the shaft against the uppermost locking spacer  28   a  and the lowermost float  24  rises up the shaft against the middle locking spacer  28   b . As the level of fluid  26  in the reservoir  18  decreases, the uppermost float  22  would be the first to lose buoyancy. As this buoyancy is lost, the uppermost float  22  slides down the shaft  12  until it meets middle locking spacer  28   b . This movement of the uppermost float  22  from the upper locking spacer  28   a  to the middle locking spacer  28   b  causes the communication between the float  22  and the switch  42  inside the shaft  12  to move the switch  42  from an open state to a closed state. 
     As the level of fluid  26  continues to drop, the lowermost float  24  likewise loses buoyancy. As this buoyancy is lost, the lowermost float  24  also slides down the shaft  12  from the middle locking spacer  28   b  to the lower locking spacer  28   c . In this case, the communication between the lowermost float  24  and the switch  44  inside the shaft  12  causes the switch  44  to move to an open state once the lowermost float  24  reaches the lower locking spacer  28   c.    
     Referring to  FIG. 4 , the electrical wiring and operation of the device  10  is illustrated and described. The float switches  42 ,  44  are associated with the first and second floats  22 ,  24  respectively. The first float switch  42  is configured for a default closed position (as illustrated) when the first float  22  is in the lowered position. One side of the first float switch  42  is electrically connected by a first conductor  46  to the low fluid level alert indicator  36 , which may take the form of a light  36   a , an alarm  36   b , or both. The low fluid level alert light  36   a  preferably has a yellow or amber color, but may be any color designated to communicate the appropriate warning. The alarm  36   b  generates an audible warning of about seventy-two decibels or greater. The other side of the first float switch  42  is connected by a primary conductor  48  which is in turn connected to a device control switch  50  and a system relay  52 . 
     In this illustration, the system switch  50  is the on/off switch for the system power source (not shown) which draws on the fluid in the reservoir  18 . A person skilled in the art will realize that the switch  50  may comprise an on/off switch for any device or machine that may draw fluid from a reservoir. When the switch  50  is in the off (open) position as shown, electricity is not supplied to the system. When the switch  50  is in the on (closed) position, electricity is supplied from the ignition through the switch  50  to the system. 
     The second float switch  44  is configured for a default open position as shown when the second float  24  is in the lower position. One side of the second float switch  44  connects to the same primary conductor  48  that connects the first float switch  42  to the switch  50 . The other side of the second float switch  44  is connected by a second conductor  54  to the system relay  52 . 
     The system relay  52  has four main inputs/outputs. A first input is conducted from the switch  50  and is configured to supply electricity for the system relay  52  to direct to the various outputs. Another input is received from the second float switch  44  through the second conductor  54 . As the second float  24  reaches the bottom locking spacer  28   c , the second float switch  44  is opened and the second conductor  54  stops conducting electricity to the system relay  52 . The system relay  52  has two main outputs. The first is to the control device  60 . A typical control device would comprise a PTO solenoid valve or similar mechanism. When the second float switch  44  is in the closed position, the system relay  52  is configured to conduct electricity to the control device  60  such that the device may continue to draw fluid  26  from the reservoir  18 . The second major output from the system relay  52  comprises shutdown conductor  56  which communicates with the stop alert indicator  38 , preferably a light. When the second float switch  44  is in the open position, the system relay  52  is configured to conduct electricity through the shutdown conductor  56  to the stop alert light  38  and not to the control device  60 . In this way the device is configured to automatically stop drawing fluid  26  from the reservoir  18 . The stop alert light  38  is preferably red, but may be any color configured to communicate an emergency or shutoff of the system. The system includes an override switch  40  connected by override conductor  62  to the electrical ignition and the control device  60 . The override switch  40  has an electrical connection to the ignition so as to provide electricity when in override. Appropriate ground connections  64  are arranged throughout the system. 
     In operation, as the first float  22  reaches the lower position, the first float switch  42  is closed connecting the electricity through primary conductor  48  to the low fluid level alert light  36   a  and/or alarm  36   b , activating the same. At this time, the second float  24  is still in the up position and the second float switch  44  is closed so as to conduct electricity away from the stop alert light  38  and continue conducting electricity through the relay  52  to the control device  60 . As the fluid level continues to drop, the second float  24  reaches the lower position opening the second float switch  44 . Upon this occurrence, electricity is no longer conducted through the second conductor  54  to the relay  52 . Electricity is instead supplied through only the primary conductor  48  where the relay  52  is configured to trip the stop alert light  38  and stop conducting electricity to the control device  60 . In this way, the system automatically shuts off the device  60 , stopping the flow of fluid from the reservoir  18  to the control device  60 . 
     The override switch  40  is configured to provide a separate supply of electricity to the control device  60  without passing through the system relay  52 . The override switch  40  fails to an open position and is only closed when a user activates the switch or depresses a button. 
     Although several embodiments have been described in detail for purposes of illustration, various modifications may be made without departing from the scope and spirit of the invention. Accordingly, the invention is not to be limited, except as by the appended claims.