Abstract:
Systems are provided to avoid overloading a truck&#39;s bed and/or overloading a truck&#39;s towing capacity. Systems are also provided to detect and alert drivers of unbalanced loads.

Description:
TECHNICAL FIELD 
     This disclosure relates to load-sensing systems for trucks to avoid or prevent overloading truck beds and/or the towing capacity of a light-duty truck. 
     BACKGROUND 
     Light-duty trucks have grown in popularity relative to heavy-duty trucks in part because of their ability to achieve higher gas mileage. Due to the ever-increasing prices for oil and gas, the need for lighter weight and lighter duty trucks is expected to continue to grow. 
     Many truck owners, however, still choose to purchase a truck rather than a car because they have a need to carry loads that are less than ideal for cars to carry. For example, trucks with an open bed are more able to accommodate oddly shaped and large objects that may need to be carried when a vehicle owner moves from one residence to another. Additionally, a vehicle owner may prefer to pull a recreational vehicle such as a snowmobile or a jet ski with a truck rather than a car. A light-duty truck might be ideal for a consumer who will use the vehicle primarily as a commuter vessel, but who occasionally needs to carry loads that are less than suitable for cars. 
     Light-duty trucks sometimes have a physical appearance that is similar to that of a heavy duty truck. For this reason, it may be tempting for drivers of such vehicles to attempt to use light-duty trucks as though they were heavy-duty trucks on occasion. Such use can be problematic, however. For example, such use can reduce gas mileage performance of the light-duty truck. Such use can also harm the light-duty truck in many ways, including placing undue wear and tear on a suspension system and additional strain on the engine. 
     In presently available systems for light-duty trucks, it may be difficult for a light-duty truck driver to know when he or she has overloaded the vehicle bed or overloaded the towing capacity of the truck, or has an unbalanced load. Thus, he or she can unwittingly carry a load that is higher than that for which the truck is rated, and the load may be uneven. 
     It would therefore be desirable to provide a system for light-duty truck drivers so that they could readily know, when carrying a load in a truck bed or towing a trailer, whether the load is within the recommended limit for the truck or whether the recommended limit has been exceeded. It is desirable for such a system to be able to detect uneven loads. It is also desirable for such a system to be simple to manufacture, install and use. It is also desirable for such a system to be cost-effective. 
     SUMMARY 
     Systems are provided to address, at least in part, one or more of the needs or desires left unaddressed by prior systems and methods. 
     A system to avoid overloading a truck bed is provided. The system includes a sensing system to detect height or weight of a truck bed. The system also includes a controller to compare the sensed value with a predetermined threshold. If the sensed value differs from the threshold in a predetermined manner, a signal is configured to trigger a warning to the driver. 
     A system to avoid overloading a truck&#39;s towing capacity is also provided. The system includes a sensing system to determine the angle of an accelerator pedal. The system also includes a controller to compare the sensed angle and a speed of the truck against predetermined threshold relationships of accelerator pedal angle and truck speed. If the speed of the truck is lower than the expected truck speed identified in the predetermined threshold relationship for the sensed angle, a signal is configured to trigger a warning to the driver. 
     Another system to avoid overloading a truck&#39;s towing capacity is provided. The system includes a sensing system to determine towing strain. A controller in the system is configured to compare the sensed strain against a predetermined threshold. If the sensed strain is greater than the threshold, a signal is configured to trigger a warning to the driver. 
     These and other embodiments will become apparent upon a reading of the application and appended claims, without departing from the scope and spirit of the invention as set forth in the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1 . depicts a height-based sensing system for determining a load in a truck bed. 
         FIG. 2 . depicts a weight-based sensing system for determining a load in a truck bed. 
         FIG. 3 . depicts a system for determining whether a truck&#39;s carrying or towing capacity is overloaded. 
         FIG. 4 . depicts a system for determining whether a truck&#39;s towing capacity is overloaded. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  depicts a height-based sensing system for determining a load in a truck bed  10 . When a load is placed in truck bed  10 , it applies a downward force F, acting on the truck bed  10  and, in turn, suspension component  20 . As the magnitude of F increases, truck bed  10  lowers. 
     Suspension component  20  may contain one or more embedded height sensors  25  or may be in communication with one or more height sensors  25  which can determine the relative height of the truck bed  10 . In instances where multiple height sensors  25  are used, height sensors  25  may be positioned so that the evenness of the truck bed  10  can be determined. For example, height sensors  25  in a rear right location might sense a lower height of truck bed  10  than height sensors  25  in a front left location of truck bed  10 . Height sensors  25  may be any known height sensors, analog or digital, including those described in U.S. Pat. No. 5,031,934 or 5,083,454, both of which are incorporated by reference in their entireties. One or more of the height sensors  25  may comprise or be in communication with a Hall-effect device  30 . 
     In a low-cost illustrative example involving multiple Hall-effect devices  30  on or in communication with suspension component  20 , the Hall-effect devices  30  send a signal to controller  40  indicating the height of the truck bed  10 . The controller  40  may contain logic that determines whether sensed evenness of the load falls within predetermined ranges. If the load is uneven (the difference between the highest sensor  25  and the lowest sensor  25  is greater than a predetermined value), a signal may be sent to a warning system  50  to alert the driver. The warning system  50  may be any known auditory and/or visual warning system. 
     The controller  40  may also contain logic that calculates an average height from the input of the multiple height sensors  25  and/or Hall-effect devices  30 . In this case, the controller  40  compares the sensed (or averaged) height of the truck bed  10  and compares it to a threshold value. If the height is lower than the predetermined threshold for height, a signal may be sent to a warning system  50  to alert the driver. The warning system  50  may be any known auditory and/or visual warning system. 
       FIG. 2  depicts a weight-based sensing system for determining a load in a truck bed  10 . When a load is placed in truck bed  10 , it applies a downward force F, acting on the truck bed  10  and, in turn, suspension component  20 . As the magnitude of F increases, the weight of the truck bed  10  acting on the suspension component  20  increases. 
     Suspension component  20  may contain one or more embedded weight sensors  28  or may be in communication with one or more weight sensors  28  which can determine the weight of truck bed  10  with its load therein. In instances where multiple weight sensors  28  are used, weight sensors  28  may be positioned so that the evenness of the load in truck bed  10  can be determined. For example, weight sensors  28  in a rear right location might sense a greater weight of truck bed  10  than weight sensors  28  in a front left location of truck bed  10 . Weight sensors  28  may be any known weight sensors, including load cells, pressure sensors in an air suspension, etc. An electronic module may supply power to the weight sensor  28  and provide the associated buffer circuitry to transform a signal that is emitted from the weight sensor  28  into an operator indicator. 
     In an illustrative example involving multiple weight sensors  28  on or in communication with suspension component  20 , the weight sensors  28  send a signal to controller  40  indicating the weight of the truck bed  10 . The controller  40  may contain logic that determines whether sensed evenness of the load falls within predetermined ranges. If the load is uneven (the difference between the sensor  28  detecting the greatest weight and the sensor  28  detecting the lowest weight is greater than a predetermined value), a signal may be sent to a warning system  50  to alert the driver. The warning system  50  may be any known auditory and/or visual warning system. 
     The controller  40  may also contain logic that calculates an average weight from the input of the multiple weight sensors  28 . In this case, the controller  40  compares the sensed (or averaged) weight of the truck bed  10  and compares it to a threshold value. If the weight exceeds the predetermined threshold for weight, a signal may be sent to a warning system  50  to alert the driver. The warning system  50  may be any known auditory and/or visual warning system. 
       FIG. 3  depicts a system for determining whether a truck&#39;s carrying or towing capacity is overloaded. In  FIG. 3 , two sensed inputs  100  and  110  are provided to controller  140 . Input  100  relates to the angle between the accelerator pedal and a floor board of the truck. Input  110  relates to speed of the truck. Under conditions where there is no load in a truck&#39;s bed and a truck is not towing any object, the angle of the accelerator pedal has a known relationship with the speed of the truck. As the angle grows more acute, the speed is increased, generally. The relationship need not be linear. In situations where a truck is carrying or towing a load of any kind, the angle of the accelerator pedal must become more acute to achieve the same speed as it would without a load. There is a pre-determined limit to how acute the angle must become to achieve a particular speed. Stated another way, when the angle of the accelerator pedal to the floor board is at a certain value, the truck must be going at a minimum speed unless there is undue strain on the truck from carrying or towing a load. In other words, there is a pre-determined minimum speed for particular angles of the accelerator pedal relative to the floor board, below which the load being carried by the truck is too taxing. At some point, for any given vehicle, a carrying or towing load puts too much strain on a vehicle. Logic in the controller  140  can compare the inputs  100  and  110  to predetermined thresholds to determine whether the load being carried or towed is too taxing on the truck. If it is, a signal can be sent to indicate an overload. 
     If the threshold or thresholds are exceeded (angle too low to achieve a speed or speed too low for a particular angle), then a signal may be sent to a warning system  150  to alert the driver. The warning system  150  may be any known auditory and/or visual warning system. 
       FIG. 4  depicts a system for determining whether a truck&#39;s towing capacity is overloaded. In the depicted illustrative example, truck  200  is pulling trailer  220  using hitch  210 . Hitch  210  may include one or more embedded sensors  215 . Embedded sensors  215  can be any known sensor, including a strain gauge. An electronic module can provide the power and the buffer circuitry for the sensors  215 . 
     In the case where embedded sensor  215  is a strain gauge, it sends an electrical analog signal that corresponds to the stretching of the hitch  210  by the weight of the towing load. This signal is sent to controller  240 . In controller  240 , logic is provided to determine whether the strain is over a predetermined threshold. If so, then a signal may be sent to a warning system to alert the driver. The warning system may be any known auditory and/or visual system. It may display or announce qualitative information, such as “Overload,” and/or it may display or announce quantitative information, such as precise weights and/or the amount of weight over the threshold. 
     Any one of the exemplary systems described above may be implemented independently or in combination with one another. 
     While at least one embodiment of the appended claims has been described in the specification, those skilled in the art recognize that the words used are words of description, and not words of limitation. Many variations and modifications are possible without departing from the scope and spirit of the invention as set forth in the appended claims.