Abstract:
A brake control system for towed vehicles is disclosed which provides for controlled application of hydraulic brakes in a towed vehicle in response to the application of the brakes of the towing vehicle. The system is designed in two preferred embodiments. The first embodiment is a self-contained design adapted for use with rental trailers, for example, where a plurality of towed vehicles will be associated with a particular trailer. The second embodiment is intended for hard wiring in connection with the towed and towing vehicles. In each case, superior performance is obtained because the system operates the brake system of the towed vehicle in a unique manner.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
         [0001]    None.  
         BACKGROUND OF THE INVENTION  
         [0002]    This invention relates to braking systems, in more particular, to brake control systems adapted to engage the brakes of a towed vehicles when the brakes of the towing vehicle are actuated so as to causes the brakes of the towed vehicle to assist the brakes of the towing vehicle in stopping the two vehicles. There are a number of patents and designs for braking systems intended to be employed with one vehicle being towed by another. When a vehicle is being towed by another vehicle, the braking system of the towing vehicle must function to stop both the towing vehicle and the towed vehicle, unless some auxiliary braking control is provided. The extra force of the towed vehicle on the braking system of the towing vehicle requires extra stopping distance and extra stopping time for the two vehicles. The extra weight of the towed vehicle also accelerates the wear and tear of the braking system of the towing vehicle thus increasing the frequency of repairs.  
           [0003]    It has long been known that it is possible to provide a system that applies braking force to the towed vehicle in response to brake actuation in the towing vehicle. Trailers of various size and shape, intended for towing by a towing vehicle conventionally include brake systems that are either hydraulically or electrically operated. A number of prior art devices are intended to operate with the towed vehicle braking system. While these prior art devices are acceptable for their intended purposes, they have not solved a number of problems associated with towing a second vehicle. In particular, these systems generally do not function to cause the braking system of the towed vehicle to operate as quickly as is desirable in braking situations. In addition, the prior art designs do not function properly in a number of specific operating situations. Prior art systems in which we are aware of do not engage the brakes of the towed vehicle during backing up of the two vehicles. This can be especially important, for example, in situations in which the towed vehicle is a boat type trailer and it is desired to back the trailer down an extended boat ramp.  
           [0004]    In general, there are two types of braking systems available for trailers. Legal requirement specify that all trailers that require brakes have means for activating the trailer brakes under trailer breakaway conditions. In hydraulic surge brake systems this is normally done by means of a cable or chain which is connected to the tow vehicle. Under trailer breakaway conditions, the connecting link is designed to provided mechanical activation of the master cylinder, and to maintain brake system operation as the trailer stops. If the trailer has an electric brake system, the emergency breakaway regulations require that the trailer be provided with an emergency battery back-up system that will provide electrical power to the brake magnets during trailer breakaways. In an electric breakaway system there is a breakaway switch with a pull pin and cable which, when attached to the tow vehicle provides electrical activation of the trailer brakes if the trailer disconnects from the tow vehicle during highway travel, for example. The components for this system are normally packaged as an emergency breakaway kit which has a battery and charger, emergency switch, and battery case in one package.  
           [0005]    Hydraulic surge brakes are a totally trailer self-contained braking system, requiring no electrical, hydraulic or other connection of brake sensing components to the towed vehicle for automatic operation of the trailer brakes. In a hydraulic surge brake system, the differential pressure developed between the towing vehicle and the trailer, during the braking process, creates a mechanical pressure which is applied to the push rod of the master cylinder in a hydraulic surge brake coupler. This mechanical pressure is proportional to the difference in pressure between the two vehicles and therefore, the hydraulic output of the brake coupler, and resulting brake operation, is automatic, regulated, and proportional to the amount of braking being applied by the towing vehicle.  
           [0006]    These various systems, though effective, are not without hidden problems. For example, the hydraulic surge brake system requires a certain amount of forward pressure to be effective. Backing a trailer up a hill puts pressure on the system and actuates the trailer brakes when the brakes are least needed. Backing a surge system down a hill takes away pressure and the trailer free wheels, leaving no chance of brake activation. Electric brakes work well in dry conditions, however, electric brakes are not recommended for boat trailers.  
           [0007]    The brake control system of the present invention is intended for application with surge brake systems to increase their efficiency. Certain components of the system also can be applied to electrical brake systems to improve their operation. A particularly hazardous condition can exist with respect to rental trailers which are attached to a tow vehicle without really evaluating the safety features, and particularly the brake features of the vehicle being towed. In one embodiment of the invention, the braking system is self-contained and is installed on the towed vehicle, requiring only an interconnection to the brake light system of the towing vehicle for operation. Other embodiments of invention include a hard wire system intended for use with a single towing vehicle and trailer, for example, in the common recreational use of the system.  
         BRIEF SUMMARY OF THE INVENTION  
         [0008]    In view of the foregoing, as an object of the present invention to provide a brake control system that selectively actuates and deactuates the brake system of a towed vehicle in response to the activation and unactivation of the brake system of a towing vehicle.  
           [0009]    Another object of the present invention is to provide an auxiliary brake system that actuates and deactuates the brake system of a towed vehicle in response to an electric signal that is carried from the towing vehicle to the towed vehicle.  
           [0010]    Still another object of the present is to provide a brake control system that uses the existing brakes and/or brake lines of the towed vehicle.  
           [0011]    A further object of the present invention is to provide a brake control system that uses a hydrostatic pump to apply pressure to the existing brakes and brake lines of the towed vehicle to create braking forces.  
           [0012]    Still a further object of the present invention is to provide an auxiliary brake actuator that may be easily retrofit on a variety of vehicles that are typically towed behind another vehicle.  
           [0013]    Another object of this invention is to provide a brake control system which, in one exemplary design, is self-contained and is installed on the towed vehicle.  
           [0014]    Yet another object of this invention is to provide a brake control system that is microprocessor controlled.  
           [0015]    Another object of the present invention is to provide a brake control system that is of relatively simple construction, which achieves the stated objectives in a simple effective and inexpensive manner, and which solves the problems associated with known braking systems employed with towed vehicles.  
           [0016]    In accordance with this invention, generally stated, a brake control system has a microprocessor control adapted for use in a variety of applications. In one embodiment, the system is self-contained and is intended for attachment to the towed vehicle, the towed vehicle having a hydraulic brake system. The control includes a motor driven hydrostatic pump. The motor and pump are attached to a reservoir of brake fluid and the unit is attached to the hydraulic system of the towed vehicle. A battery provides power to the motor. A microprocessor controls application of electrical energy to the pump motor, and controls charging current to the battery. Other embodiments of the invention distribute the components of the control system between the towing vehicle and the towed vehicle. 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0017]    The objects of the invention are achieved as set forth in the illustrative embodiments shown in the drawings which form a part of the specification.  
         [0018]    [0018]FIG. 1 is a diagrammatic view of one illustrative embodiment of the brake control system of the present invention;  
         [0019]    [0019]FIG. 2 is a diagrammatic view of the brake system of FIG. 1 showing a distribution of the system to a towed vehicle;  
         [0020]    [0020]FIG. 3 is a diagrammatic view of the brake control system of a towing vehicle control unit adaptable for use with either electric or hydraulic brakes on a towed vehicle; and  
         [0021]    [0021]FIG. 4 is diagrammatic view of a distribution system for permanently wired system intended for a single and user application.  
         [0022]    Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.  
     
    
     DETAILED DESCRIPTION OF INVENTION  
       [0023]    The following detailed description illustrates the invention by way of example and not by way of limitation. This description will clearly enable one skilled in the art to make and use the invention. It describes several embodiments, adaptations, variations, alternatives and uses of the invention, including what we presently believe is the best mode of carrying out the invention. As various changes could be made in the these constructions without departing from the scope of the invention, it is intended that all matter contained in the description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.  
         [0024]    Referring now to FIG. 1, reference numeral  1  indicates one illustrative embodiment of the brake control system of the present invention. The brake control system  1  includes an enclosure  2  which functions to house a plurality of components, including a motor  3  and a pump  4 . Also mounted with the enclosure  2  are a battery  5  and a microprocessor  6 .  
         [0025]    The system shown in FIG. 1 is the self-contained unit, and all components mentioned above fit and attach neatly to and/or into the enclosure  2 . Installation of the unit is as easy as mounting the enclosure  2  to a trailer (or other towed vehicle)  17 , and connecting the brake line of the trailer to a fluid fitting under the enclosure  2 , not shown. The motor  3  of the motor/pump combination is conventional and is driven by the battery  4  through the microprocessor  6 . The battery  5  is a conventional  12  volt battery, and the motor  3  is intended to operate from the  12  volts through a power modulator  7  associated with the microprocessor  6 .  
         [0026]    The microprocessor  6  includes a relay time function  8  which is interposed between the processor  6  and the battery  5 . As seen in FIG. 1, the interconnection between the system  1  and the towing vehicle  10  is accomplished through a single interconnection  11 . The interconnection  11  includes a first line  12  and a second line  13  which provide electrical input to the microprocessor  6  and corresponds to the right turn signal/brake and the left turn signal/brake input from the brake lights of the vehicle  10 . A third line  14  is connected to a charging circuit  15  which in turn is connected to the microprocessor  6  and enables the microprocessor  6  to control charging to the battery  5  whenever at least the taillight switch of the vehicle  10  is on.  
         [0027]    As shown in FIG. 1, a breakaway switch  16  is operatively connected between the towed vehicle  17  and the towing vehicle  10  and is connected to the enclosure  2 , in the embodiment illustrated. The breakaway  16  in turn is electrically connected to the microprocessor  6  and operates to cause the microprocessor  6  to apply braking signals to the motor  3  in the event of towing vehicle breakaway during use. Also shown in FIG. 1, is an on/off switch  17  which removes power from the system  1 .  
         [0028]    Referring now to FIG. 4, a permanent single end user system as shown in which certain of the components of the system are distributed between the towing vehicle  10  and the towed vehicle  17 . In this particular embodiment, a relay box  18  is preferably mounted under the hood of the vehicle  10 , near the vehicle battery  5 ′. An on/off switch  60  of the relay box applies power to the pump  4  through leads  19  and  20 . Leads  21  and  22  are connected to the battery  5 ′ and the unit transmits the power from the battery  5 ′ to the motor  3 . A lead  23  is operatively connected to a brake pedal motion detector  61 .  
         [0029]    The switch enclosure  18  may be replaced by an under dash unit  24 , if desired. The unit  24  may assume a variety of esthetic design configurations, and two such configurations as shown in FIG. 2 and FIG. 3, for example. Regardless of the configuration, the unit  24  is designed to operate with either hydraulic or electric brakes, and a mode switch  25  is provided to adjust the brake control system with the types of brakes being employed in the towed vehicle  17 . In the embodiment illustrated in FIGS. 2 and 3, a power dial position selector switch  26  also is provided.  
         [0030]    Merely by way of example, the selector switch  26  may contain the following functions. For example, we have chosen the position  1  as being the off mode, which would be used when the towed vehicle is parked for any length of time. Switch selection No.  2 , is in the embodiment illustrated, the battery connection mode and shows the battery voltage on a scale  27 . This selection will also let the operator know when the battery should be charged. As indicated above, charging may be accomplished merely by turning on the vehicle lights so that the microprocessor  6  actuates the charging circuit for the battery  12  in those units in which the battery  12  is mounted on the towed vehicle  17 . Switch selection No.  3  is the back-up mode. As indicated above, this allows the user to back up any hydraulic trailer regardless of whether the backup is occurring up hill or down hill. This setting offers an on command of the brakes for the trailer  17  for as long as the brake pedal of the towing vehicle is depressed. This is an important feature for trailers employed with recreational boats, for example, in that it is common for such trailers to be backing down long extended boat ramps.  
         [0031]    The next seven selections gives the user multiple power settings for the brakes. The dial starts from a minimum to maximum pressure setting. This allows the user to adjust for conditions in the towed vehicle  17 . This is particularly important to adjust the system operation between loaded and unloaded trailers or other towed vehicles, for example.  
         [0032]    The relay timer circuit  8  is an important feature of our invention. This system allows braking pressure to be constant for  8  seconds from the time the brake pedal in the towing vehicle is depressed. Each time the pedal is depressed, the timing function resets and the brakes continue to operate. This feature allows a vehicle to travel down long steep grades without dragging the brakes. After  8  seconds of continuous braking, the timer circuit disengages the brakes, forcing the release and reapplication of the brake pedal of the towing vehicle. This action allows for improved operation of both the towing vehicle and the towed vehicle brakes.  
         [0033]    Regardless of the configuration of the system, operation of the braking control system of the present invention is relatively simple to understand. Upon initial braking, the microprocessor  6  drives the motor pump into a spin up mode. The function insures a quick response from the electronic signal to the pressurizing of the brakes. Once spin up produces pressure to the brake lines, the pressure returns to the brake pressure setting that the driver has dialed on the control board. The control board, in the embodiment of FIG. 1, is located on the left side of the housing with LED light display and control adjust knob in plain view from the driver side of the vehicle. Operation of the system thereafter follows in tandem with the application of brakes in the first or towing vehicle.  
         [0034]    One test conducted on the control system of the present invention, a truck having a weight of 5,400 lbs. with a trailer having a weight of 12,600 lbs. on a day with the temperature of 55° F., dry pavement showed the following results. From initial start of 55 M.P.H panic stop with ABS breaking and the towing vehicle. The trailer had two axles.  
         [0035]    Braking with truck only 350 feet.  
         [0036]    Braking with utilizing the trailer only 578 feet.  
         [0037]    Braking with trailer and truck 262 feet.  
         [0038]    It may thus be observed that the brake system of this invention provides substantially improved braking capability for vehicles being towed, while providing functionality not found in prior art designs.  
         [0039]    Numerous variations, will be apparent to those skilled in the art in light of the foregoing description and accompanying drawings. For example, the location of various units of the equipment may be varied in other embodiments of the invention. As indicated, the design silhouettes for certain components may be altered. While hard wiring was indicated with respect to certain applications and signal transmissions between the towing vehicle and the towed vehicle, those skilled in the art will recognize that radio transmissions or infrared or other forms of electromagnetic or light transmissions may be employed in other embodiments of the invention. These variations are merely illustrative.