Abstract:
An electric trailer brake system includes an electric brake receiving energy from a battery. The battery is recharged by a generator disposed on the trailer independent from the towing vehicle. Recharging the batteries that power the electric brake assemblies on the trailer minimizes the effects of power restrictions caused by a standard sized connector and cable connection between the towing vehicle and cargo trailer.

Description:
BACKGROUND OF THE INVENTION 
   This invention relates to an electric brake system for a cargo trailer and specifically to a power source for powering an electric brake system for a cargo trailer. 
   Typically, heavy trucks include a truck and a cargo trailer. The truck includes an internal combustion engine that drives an alternator to generate electricity. Electric brakes mounted to the tractor are powered directly by electricity generated from the alternator. Typically, a single electric brake requires approximately 20 to 30 amperes of current during heavy stop conditions in order to have enough power to slow or stop the heavy truck. Wire sizes for transmitting electrical energy between the power source for the truck and the electric brake are sized to reduce line drop so the brake will have required voltage and current for the brake motor. There are restrictions on the size of wire used between the truck and trailer for transmitting electrical power to the electric brakes. Further, the electrical connection between the truck and trailer is a predetermined standard size wire and connector. 
   The size of the wire and the standard connector cannot be adjusted and is the limiting factor for current supplied to the electric brakes in the non-powered trailer. As appreciated an electric brake on each wheel of the cargo trailer requires approximately 20 to 30 amperes of current in order to apply sufficient braking force during a hard stop condition. The current required for all the wheels of the cargo trailer is between 360 and 440 amperes when the brakes are fully applied for a hard stop. Current losses caused by line drop through the standard sized wire and connector are such that during hard stop braking conditions the amount of available current may be insufficient to actuate the electric brakes. 
   Accordingly, it is desirable to provide a system for powering electric brakes mounted to the cargo trailer independent of power generated by the towing vehicle to minimize the limitations caused by the electrical connection between the truck and trailer. 
   SUMMARY OF THE INVENTION 
   This invention is an electric brake system for a cargo trailer including a power source independent of a powered tow vehicle for powering electric brake assemblies of the cargo trailer. 
   The electric brake system of the trailer includes an electric brake assembly mounted for braking each of the non-driven wheels of the trailer. Each electric brake assembly is connected to a battery charged by a generator driven by the axles or wheels of the cargo trailer. 
   The electric brake assembly includes a brake controller in communication with a power source. The brake controller monitors the battery and controls the generator charging the batteries that power each electric brake assembly. 
   In another embodiment of this invention the power source is a fuel cell that directs power to each of the electric brake assemblies on a demand basis or to a power storage device. In yet another embodiment of this invention, a solar panel is positioned to trickle charge the batteries that power each of the electric brake assemblies. 
   Accordingly, the electric brake system of this invention includes a power source independent of the towing vehicle to provide sufficient electrical energy for the electric brakes of the trailer to operate without increasing or changing the standard electrical connection between the powered tow vehicle and the cargo trailer. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows: 
       FIG. 1  is a schematic representation of a tractor trailer including an electric braking system for a cargo trailer; 
       FIG. 2  is a schematic representation of an alternate embodiment of the electric braking system; 
       FIG. 3  is a schematic representation of another embodiment of the electrical braking system and 
       FIG. 4  is a schematic representation of another embodiment of the electric braking system with a second trailer. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIG. 1  wherein like reference numerals designate similar arts throughout the figures, this invention is an electric brake system for a cargo trailer towed by a towing vehicle  10 . The electric brake system comprises electric brake assemblies  22  disposed at each wheel of the tow vehicle  10  and the cargo trailer  12 . Electric brakes on the towing vehicle  10  are directly powered by an engine  15  driving an alternator  13 , as is the typical configuration for motor vehicles. The wire size of the power connections  17  is sized to minimize voltage drop between the alternator  13  and brake assemblies  22 . The specific wire size of the power connections  17  may be of any size as is known by a worker skilled in the art to prevent current loss and assure that sufficient amounts of electrical energy reach each electric brake assembly  22 . 
   Electrical energy from the towing vehicle  10  is transferred to the cargo trailer  12  through a standard sized connector  20  and cable  21 . The cargo trailer  12  receives power through a fixed wire size seven-pin J560 connector and a J1067 cable. This standard combination of connector  20  and cable  21  is sized to supply sufficient power to operate taillights. Anti-lock braking system and any other systems disposed on the cargo trailer  12 . The electric brake system requires an additional 80 to 160 amperes of current. The increased requirement for electrical energy in the cargo trailer  12  magnifies the effects of any current loss. The electric brake system of this invention includes an alternate independent power source located on the cargo trailer  12  in order to assure sufficient electrical energy for electric brake assemblies  22 . Data is exchanged between the controller  28  and main controller  30  through a power line carrier  36 . Information through the power line carrier  36  includes information on brake conditions, power source condition, brake wear, temperature and other required data to the main controller  30 . 
   Each electric brake assembly  22  is powered by a separate battery  24 . Each battery  24  is trickle charged controlled by controller  28  from the alternator  13  of the towing vehicle  10  to maintain sufficient electrical charge for operation of the electric brake assemblies  22 . However, because of the current loss between the alternator  13  and each battery  24  disposed within the cargo trailer  12 , a generator  26  positioned on the cargo trailer  12  also provides electrical energy to constantly charge the batteries  24  in order to maintain requisite electrical charge for hard stopping of the towing vehicle  10  and cargo trailer  12 . 
   The generator  26  is driven by rotating members of the cargo trailer  12 , such as the trailer wheels  18  or the trailer axle  34 . The generator  26  is driven by the rotation of the wailer wheels  18  and can be mechanically connected to any of the rotating members such as the axle  34  or the trailer wheels  18 . The generator  26  is also in electrical communication with and controlled by controller  28 . The generator  26  is selectively engaged to operate in response to a specific energy level within each of the batteries  24 . Each of the electric brake assemblies  22  include a brake controller  32  that controls actuation and monitors energy levels within the battery  24 . Upon attaining a predetermined energy level, the brake controller  32  signals the need for additional energy, the controller  28  signals the generator  26  to engage and produce additional electrical energy to recharge the batteries  24 . 
   Referring to  FIG. 2 , another embodiment of this invention includes a solar panel  40  to supplement the power produced by the generator  26  to charge the batteries  24 . Solar panels  40  provide continuous electrical charge to the batteries  24  even in the absence of movement of the cargo trailer  12 . Each electrical brake assembly  22  is provided with the individual battery  24  that includes sufficient electrical energy for a desired number of hard stops. The cargo trailer mounted generator  26  supplements trickle charging provided by power from the alternator  13  ( FIG. 1 ). The solar panel  40  operates to maintain the desired level of charge to power the electric brakes  22  even daring stationary periods. 
   Referring to  FIG. 3 , another embodiment of this invention includes a fuel cell  38  for powering the electric brake assemblies  22 . The fuel cell  38  converts chemical energy to electrical energy as required by each of the electric brake assemblies  22 . The specific type of fuel cell  38  utilized in the electric brake system is application specific and any type or configuration of fuel cell is within the contemplation of this invention. Many types of fuel cells using different chemical components and configurations are within the contemplation of this invention. 
   This invention is an alternate independent power source for powering and charging the electric brake assemblies  22  disposed within the cargo trailer  12 . Although, specific types of power sources are described, it is within the contemplation of this invention that other power generation means known to a worker skilled in the art for supplying electrical energy to actuate the electric brake assemblies  22  are within the scope of this invention. 
   Referring to  FIG. 4 , a second trailer  50  is towed by the cargo trailer  12 . As appreciated, the current drop from the towing vehicle  10  to the cargo trailer  12 , and then to the second trailer  50  is such that sufficient electrical energy would not be available to actuate the electric brake assemblies  22  of the second trailer  50 . The system of this invention includes the generator  26  to provide additional electric energy to the batteries  24  that power actuation of the electric brake assemblies  22 . The second trailer  50  includes a second controller  52  and power cable  54  that is in communication with the controller  28 . Further, a second power line cater  58  communicates information on brake system status to a main controller  30  ( FIG. 1 ). As appreciated, the second trailer  50  may also include alternate energy storage or producing devices such as the fuel cell  38  and the generator  26 . 
   Referring back to  FIG. 1 , during operation, the towing vehicle  10  supplies current to electric brake assemblies  22  disposed at driven wheels  16  and non-driven wheels  14 . The main controller  30  is in communication with the trailer controller  28 . Communication between the main controller  30  and controller  28  actuates and controls actuation of the electric brake assemblies  22  at each of the trailer wheels  18 . 
   The main controller  30  controls actuation of the electric brake assemblies  22  Electrical energy for powering and actuating the electric brake assemblies  22  comes from the batteries  24  disposed on the trailer  12 . The alternator  13  of the towing vehicle provides a continuous trickle charge to the batteries of the cargo trailer  12 . The trickle charge provided by the alternator  13  is not sufficient to assure required power levels to actuate the electric brake assemblies  22 . Further, the standard sized connector  20  and cable  21  causes a large current drop that in some cases can cause insufficient power to be transferred to the electric brake assemblies  22 . 
   The generator  26  provides additional energy to charge the batteries  24  independent of the towing vehicle  10 . The generator  26  communicates power to the batteries without the limitation of standard connector and wire size. The power transfer lines  42  on the trailer  12  are sized to minimize any instance of current drop without modifying the connector  20  and cable  21 . It is within the contemplation of this invention that any power source that is known to a worker skilled in the art can be applied to provide sufficient energy required to operate the electric brake assemblies  22 . 
   The foregoing description is exemplary and not just a material specification. The invention has been described in an illustrative manner, and should be understood that the terminology used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the present invention are possible in light of the above teachings. The preferred embodiments of this invention have been disclosed, however, one of ordinary skill in the art would recognize that certain modifications are within the scope of this invention. It is understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. For that reason the following claims should be studied to determine the true scope and content of this invention.