Patent Publication Number: US-2019168773-A1

Title: Trailer hauling load limit protection system

Description:
BACKGROUND 
     A vehicle may be configured to tow a trailer. The maximum weight a vehicle may tow is a function of the design and configuration of the vehicle. If the vehicle has a trailer hitch and is towing a trailer, there is a maximum overall weight of the vehicle and trailer combination, composed of an overall weight of the vehicle and a weight of the trailer, that should not be exceeded. Although the maximum values for the vehicle and trailer weights are typically recorded in the vehicle&#39;s user manual, or otherwise made available to the vehicle operator, in practice, many users may not be aware of the significance of these parameters, and if they are, may not pay attention to them when loading their vehicle and/or trailer. It may therefore be the case that the permitted maximum weight values are exceeded and a vehicle and/or trailer is overloaded. As a result, the dynamics of the vehicle and/or trailer that is overloaded may be degraded and/or the structural integrity of the vehicle compromised. 
     SUMMARY 
     Disclosed is a trailer load limit protection system that limits operation of a vehicle when towing a trailer having a weight that exceeds a maximum allowable weight limit for the vehicle. The trailer load limit protection system limits operation of the vehicle when the protection system determines that an actual acceleration of the vehicle when towing the trailer is less than a predicted vehicle acceleration for the vehicle when towing a trailer having a weight equal to a maximum allowable trailer weight for the vehicle. Vehicle operation may also be limited when the trailer load protection system determines that an actual transmission shift point of a transmission on the vehicle is occurring before a predicted transmission shift point for the transmission when towing a trailer having a weight equal to a maximum allowable trailer weight for the vehicle. Vehicle operation may be limited by controlling a maximum allowable speed of the vehicle or preventing the transmission on the vehicle from being shifted from a park position to a drive position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The various features, advantages and other uses of the present apparatus will become more apparent by referring to the following detailed description and drawings, in which: 
         FIG. 1  is a schematic illustration of a vehicle towing a trailer; 
         FIG. 2  is a schematic illustration of the vehicle employing a trailer load limit protection system; and 
         FIG. 3  is a schematic illustration of the trailer load limit protection system. 
     
    
    
     DETAILED DESCRIPTION 
     A trailer load limit protection system is disclosed. The trailer load limit protection system is configured to avoid damage to a vehicle and minimize disruption of vehicle dynamics that may occur when towing a trailer that exceeds a maximum allowable weight for the vehicle. The vehicle may employ sensors for monitoring operating parameters of the vehicle, such as, for example, vehicle speed, accelerator pedal position and fuel flow rates. Data collected from the various sensors may be used to determine a weight of the trailer being towed. If the determined trailer weight exceeds a maximum allowable trailer weight for the vehicle a control module within the vehicle may initiate one or more protective measures designed to avoid damage to the vehicle and minimize degradation of vehicle dynamics that may occur when towing a trailer that exceeds the maximum allowable weight limit for the vehicle. The protective measures may include limiting a maximum speed of the vehicle and locking a transmission shift mechanism in a park position to prevent the vehicle from being driven. 
     Referring now to the discussion that follows and the drawings, illustrative approaches to the disclosed systems and methods are described in detail. Although the drawings represent some possible approaches, the drawings are not necessarily to scale and certain features may be exaggerated, removed, or partially sectioned to better illustrate and explain the present invention. Further, the descriptions set forth herein are not intended to be exhaustive or otherwise limit or restrict the claims to the precise forms and configurations shown in the drawings and disclosed in the following detailed description. 
     With reference to  FIGS. 1 and 2 , a vehicle  20  may be configured for towing a trailer  22 . The vehicle  20  is illustrated in the drawing figures as a pickup truck, but may have a different configuration, such as, for example, a sport utility vehicle (SUV). The vehicle  20  may include a trailer hitch  24  for attaching the trailer  22  to the vehicle  20 . The trailer hitch  24  may be suitably attached to a portion of the vehicle  20 , such as a frame. The trailer  22  may be attached to the vehicle  20  by connecting a tongue  26  of the trailer to a ball  28  on the trailer hitch  24 . The trailer  22  may have various configurations. 
     With reference to  FIGS. 2 and 3 , the vehicle  20  may include a trailer load limit protection system  30  configured to activate various protective measures designed to help prevent damage to the vehicle  20  and minimize disruption of vehicle dynamics in the event a vehicle operator attempts to tow a trailer that exceeds a maximum allowable trailer weight for the vehicle  20 . Vehicle dynamics describes how a vehicle responds to forces imposed on the vehicle when in motion. These forces may include steering, cornering, braking and acceleration forces, as well as forces due to external factors, such as wind and road grade (i.e., slope and pitch). The trailer load limit protection system  30  may be used with any type of vehicle, including but not limited to traditional vehicles, electric vehicles, passenger vehicles, sports utility vehicles (SUVs), cross-over vehicles, trucks, vans, buses, recreational vehicles (RV), as well as others. 
       FIG. 2  provides a schematic illustration of the trailer load limit protection system  30  installed on the vehicle  20 . The trailer load limit protection  30  system may determine an estimated weight of the trailer  22  and, if necessary, initiate various protective measures to prevent damage to the vehicle and/or disruption of vehicle dynamics. The trailer load limit protection system  30  may utilize various vehicle sensors to collect vehicle operational and performance parameters and/or data that may be used to determine a weight of the trailer  22 . The vehicle sensors operate to transmit a data signal indicative of a corresponding vehicle operating parameter. These vehicle sensors may include, for example, a vehicle speed sensor  32 , an accelerator pedal position sensor  34  for detecting a position of an accelerator pedal  35 , and a fuel flow sensor  36 . Vehicle operating parameters monitored by the vehicle sensors may include, for example, a vehicle speed and/or acceleration, a position of an accelerator pedal and a fuel flow rate. The trailer load limit protection system  30  may also access vehicle operational and performance parameters, data and information collected or stored in other vehicle systems to be used in whole or part by the trailer load limit protection system  30  when determining a weight of the trailer  22 . Any number of different sensors, components, devices, modules and systems may provide data and information to the trailer load limit protection system  30  that may be used to determine a weight of the trailer  22 . The sensors  32 ,  34  and  36  may be directly or indirectly coupled to a control module  38 . The sensors  32 ,  34  and  36  may be integrated within another vehicle component, device, module or system, such as, for example, as part of an engine control module (ECM). Other components may be included in or employed by the trailer load limit protection system  30 , as the system is not limited to any particular sensor or sensor arrangement. 
     The vehicle speed sensor  32  may provide the trailer load limit protection system  30  with readings or other information that may be used by the trailer load limit protection system  30  for determining a weight of the trailer  22 . For example, the vehicle speed sensor  32  may generate a speed reading indicative of a vehicle speed and/or an acceleration reading corresponding to a vehicle acceleration. The vehicle speed sensor  32  may be directly or indirectly coupled to the control module  38 . The vehicle speed sensor  32  may be part of some other vehicle device, module or system, such as, for example, an engine control module (ECM). 
     The trailer load limit protection system  30  may employ a trailer sensor  40  that provides the trailer load limit protection system  30  with readings or other information indicating that the trailer  22  is attached to the vehicle  20 . The trailer sensor  40  may be configured to generate a signal that may be transmitted to the control module  38  indicating the presence of the trailer  22 . 
     The control module  38  may include any variety of electronic processing devices, memory devices, input/output (I/O) devices, and/or other components, and may perform various control and/or communication related functions. The control module  38  may include a memory device  42  operable for storing various sensor readings, look up tables or other data structures, algorithms used to determine a weight of the trailer  22 , as well as other information and software. The memory device  42  may also store pertinent characteristics and background information pertaining to vehicle  20 . The control module  38  may include a central processing unit (CPU)  44 , such as a microprocessor, that executes instructions for software, firmware, programs, algorithms, scripts, and the like, that may be stored in the memory device  42  and may be used by the trailer load limit protection system  30  when determining a weight of the trailer  22 . The control module  38  may be electronically connected to sensors, as well as other vehicle components, devices, modules and systems via various vehicle communication systems and networks and can communicate and interact with them when appropriate. 
     The control module  38  may employ various schemes for assessing whether the weight of the trailer  22  exceeds the allowable maximum weight limit for the vehicle  20 . For example, the control module  38  may include a vehicle acceleration model  46  stored in the memory device  42 . The vehicle acceleration model  46  may include expected vehicle acceleration rates for when the vehicle  20  is towing a trailer at the maximum allowable trailer weight limit. The expected vehicle acceleration rates may be correlated to corresponding accelerator pedal  35  positions and/or fuel flow rates. The control module  38  may compare an actual vehicle acceleration to an expected vehicle acceleration when determining if the weight of trailer  22  exceeds the maximum allowable trailer weight limit for the vehicle  20 . The “actual vehicle acceleration” corresponds to the acceleration that is actually experienced by the vehicle  20 . The “actual vehicle acceleration” may be determined, for example, based on the speed signal transmitted from vehicle speed sensor  32 . The “expected vehicle acceleration” corresponds to the acceleration that is expected or anticipated of the vehicle  20  when towing a trailer at the allowable maximum trailer weight limit for the vehicle  20  based on a position of the accelerator pedal  35  and/or fuel flow rate. The control module  38  may determine from the vehicle acceleration model  46  an expected vehicle acceleration based on the accelerator pedal  35  position and/or fuel flow rate. The accelerator pedal position sensor  34  may be used to detect the position of the accelerator pedal  35  and the fuel flow sensor  38  may be used to detect the fuel flow rate. The control module  38  may determine whether a weight of the trailer  22  exceeds the maximum allowable trailer weight for the vehicle  20  by evaluating if the vehicle  20  is under accelerating or over accelerating. This may be accomplished by comparing the actual vehicle acceleration to the expected vehicle acceleration. If the actual vehicle acceleration is less than the expected vehicle acceleration, the control module  38  may determine that the weight of the trailer  22  exceeds the maximum allowable trailer weight limit for the vehicle  20  and the control module  38  may proceed to initiate any of various protective measures to prevent damage to the vehicle  20  and/or a significant reduction in vehicle dynamics. If the actual vehicle acceleration is greater than the expected vehicle acceleration, the control module  38  may determine that the weight of the trailer  22  is less than the maximum allowable trailer weight limit for the vehicle  20  and the control module  38  will not proceed to initiate protective measures. 
     The control module  38  may also employ a transmission shift point model  48  to access whether the trailer  22  exceeds the maximum allowable trailer weight limit for the vehicle  20 . The transmission shift point model  48  may be stored in the memory device  42 . The transmission shift point model  38  may include expected transmission shift points for when the vehicle  20  is towing a trailer at the maximum allowable trailer weight for the vehicle  20 . The expected transmission shift points may be correlated to corresponding positions of accelerator pedal  35  and/or fuel flow rates. The accelerator pedal position sensor  34  may be used to detect the position of the accelerator pedal  35  and the fuel flow sensor  38  may be used to detect the fuel flow rate. The control module  38  may compare an actual transmission shift point to an expected transmission shift point to determine if the weight of the trailer  22  exceeds the maximum allowable weight limit for the vehicle  20 . The “actual transmission shift point” corresponds to the transmission shift point that is actually experienced by the vehicle  20 . The “actual transmission shift point” may be determined based in data/information received from a device used to control operation of the vehicle transmission, for example, a transmission control module. The “expected transmission shift point” corresponds to the transmission shift point that is expected or anticipated of the vehicle when towing a trailer at the allowable maximum trailer weight limit for the vehicle  20  based on a position of the accelerator pedal  35  and/or fuel flow rate. The control module  38  may determine from the transmission shift point model  38  the expected transmission shift points based on the accelerator pedal  35  position and/or fuel flow rate. The control module  38  may determine whether the weight of the trailer  22  exceeds the maximum allowable trailer weight limit for the vehicle  20  by evaluating if the actual transmission shift points are occurring sooner or later than expected by comparing the actual transmission shift points to the expected transmission shift points. If the actual transmission shift points are occurring later than the expected transmission shift points, the control module  38  may determine that the weight of the trailer  22  exceeds the maximum allowable trailer weight limit for the vehicle  20  and the control module  38  may proceed to initiate any of various protective measures to prevent damage to the vehicle  20  and/or a significant reduction to vehicle dynamics. If the actual transmission shift points are occurring sooner than the expected transmission shift points, the control module  38  may determine that the weight of the trailer  22  is less than the maximum allowable trailer weight limit for the vehicle  20  and the control module  38  will not proceed to initiate protective measures. 
     The control module  38  may activate various vehicle protection measures in instances where the trailer load limit protection system  30  determines that the trailer  22  exceeds the maximum allowable trailer weight limit for the vehicle  20 . The vehicle protection measures may include transmitting a warning that the trailer exceeds the maximum allowable weight limit, preventing the vehicle  20  from operating above a selected maximum speed and preventing a transmission in the vehicle from being shifted out of a park position and into a drive position. 
     If the trailer load limit protection system  30  determines that the trailer  22  being towed by the vehicle  20  exceeds the maximum allowable trailer weight limit for the vehicle  20 , the control module  38  may transmit a signal for activating an alarm  49  to notify the vehicle operator of the situation. The alarm  49  may utilize various warning schemes, which may include, for example, emitting an audible and/or visual warning. The alarm  49  may also provide haptic feedback that applies forces, vibrations, or motions to a vehicle operator to alert them of the situation. The alarm  49  may be located at various locations within a passenger compartment of the vehicle  20 . The alarm  49  may include a single warning device or may include multiple warning devices arranged throughout the passenger compartment. 
     The vehicle protection measures may include limiting a maximum speed of the vehicle. If the trailer load limit protection system  30  determines that the trailer  22  being towed by the vehicle  20  exceeds the maximum allowable trailer weight limit for the vehicle  20 , the control module  38  may initiate a protective measure to prevent the vehicle  20  from being operated above a selected maximum speed, such as, for example, 25 miles/hour (MPH). This may be accomplished in a variety of ways. For example, the control module  38  may directly or indirectly interact with a fuel flow control module  50  to control an amount of fuel being delivered to an engine in the vehicle  20  to limit the maximum speed of the vehicle. The control module  38  may also interact with other vehicle systems that may have control over the vehicle fueling system, and transmit instructions to the other vehicle system to limit the amount of fuel delivered to the vehicle engine as a way of limiting the maximum allowable speed of the vehicle  20  when towing a trailer that exceeds the maximum allowable weight limit for the vehicle. The control module  38  may also interact with any other vehicle system that may be used to control a speed of the vehicle  20 . In which case, the control module  38  may transmit an appropriate control signal to the other vehicle system with instructions to limit the maximum allowable vehicle speed below the determined maximum speed. 
     The trailer load limit protection system  30  may also be configured to prevent the transmission of the vehicle from being shifted out of park and into drive when the trailer load limit protection system  30  determines that a weight of the trailer  22  exceeds the maximum allowable weight limit for the vehicle  20 . For example, the vehicle  20  may include a shift lever  52  for controlling a transmission in the vehicle  20 . The shift lever  52  may be manually actuated by a vehicle operator for shifting the vehicle transmission between a first position, for example, a park position, and a second position, for example, a drive position. The manually actuated shift lever  52  may include a safety switch  54  that operates to prevent the shift lever  52  from unintentionally being moved from the first position (i.e., park position) to the second position (i.e., drive position). A vehicle operator may manually release the safety switch  54  by depressing a button on the safety switch  54  to enable the vehicle operator to manually move the shift lever  52  from the first position to the second position. 
     Operation of the safety switch  52  may be directly or indirectly controlled by the control module  38 . For example, in instances where the trailer load limit protection system  30  determines that a weight of the trailer  22  exceeds the maximum allowable weight limit for the vehicle  20 , the control module  38  may transmit a signal to the safety switch  54 , or a system used to control operation of the safety switch  54 , with instructions to prevent the safety switch  54  from being actuated and thereby preventing the vehicle operator from moving the shift lever  52  from the first position (i.e., the park position) to the second position (i.e., drive position). This is an example of how the trailer load limit protection system  30  may prevent the vehicle  20  from being driven when towing a trailer  22  that exceeds the allowable maximum trailer weight limit for the vehicle  20 . The trailer load limit protection system  30  may also control and/or interact with other vehicle system, such as a transmission control module (TCM), that may be activated to prevent the vehicle transmission from being shifted out park and into drive. 
     It is intended that the scope of the present methods and apparatuses be defined by the following claims. However, it must be understood that the disclosed systems and methods may be practiced otherwise than is specifically explained and illustrated without departing from its spirit or scope. It should be understood by those skilled in the art that various alternatives to the configurations described herein may be employed in practicing the claims without departing from the spirit and scope as defined in the following claims. The scope of the disclosed systems and methods should be determined, not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. It is anticipated and intended that future developments will occur in the arts discussed herein, and that the disclosed systems and methods will be incorporated into such future examples. Furthermore, all terms used in the claims are intended to be given their broadest reasonable constructions and their ordinary meanings as understood by those skilled in the art unless an explicit indication to the contrary is made herein. In particular, use of the singular articles such as “a,” “the,” “said,” etc., should be read to recite one or more of the indicated elements unless a claim recites an explicit limitation to the contrary. It is intended that the following claims define the scope of the device and that the method and apparatus within the scope of these claims and their equivalents be covered thereby. In sum, it should be understood that the device is capable of modification and variation and is limited only by the following claims.