Vehicle diagnostic system

Abstract

A monitoring and information system for a vehicle's brakes and tires. The system includes one or more position sensors and/or temperature sensors that are used to measure parameters of the vehicles brakes and tires. The measured parameters are compared to known threshold parameters with one or more comparitors. When one of the measured parameters is outside the limits of one of the threshold parameters, the system provides a signal indicating that an undesirable condition exists on one of the vehicles brakes or tires and provides information about the undesirable condition.

I claim:  
     
         1 . A method of alerting a vehicle operator to a brake assembly condition comprising the steps of: 
 a) measuring a distance from a brake lining pad to an inner surface of a brake drum with a position sensor;    b) comparing the distance from the pad to the inner surface to a predetermined value; and    c) providing a signal to the vehicle operator indicating brake drag when the distance from the brake lining pad to the inner surface of the brake drum is not greater than the predetermined acceptable value.    
     
     
         2 . The method of  claim 1  wherein said predetermined value is 0.  
     
     
         3 . The method of  claim 1  wherein said predetermined value is equal to the allowable brake run out.  
     
     
         4 . The method of  claim 1  wherein measuring the distance from the brake lining pad to the inner surface is accomplished by measuring relative linear motion of the brake shoe with respect to the position sensor when the brake shoe is moved between the disengaged position and the engaged position.  
     
     
         5 . The method of  claim 1  wherein the position sensor is a linear variable differential transformer and measuring the distance from the brake lining pad to the inner surface of the brake drum comprises operably connecting the transformer to a brake shoe, moving said brake shoe between a disengaged position and an engaged position and measuring an electric signal produced by said transformer to determine the distance from the brake lining pad to the inner surface of the brake drum.  
     
     
         6 . A method of alerting a vehicle operator of an undesirable brake condition, comprising: 
 a) measuring a temperature of a wheel component;    b) comparing the temperature of the wheel component with a known threshold temperature;    c) measuring a time period that the wheel component temperature exceeds the known threshold temperature;    d) comparing the measured time period with a known soak time; and    e) providing a signal to an operator of the vehicle indicating an undesirable condition when the temperature of the wheel component has exceeded the known threshold temperature for longer than the known soak time.    
     
     
         7 . The method of  claim 6  wherein said wheel component is a brake component and said signal is intended to alert such operator that brake fade is possible.  
     
     
         8 . The method of  claim 6  wherein said wheel component is a brake component and said signal is intended to alert such operator of brake fade.  
     
     
         9 . The method of  claim 6  wherein said signal is intended to alert such operator that tire ply separation is possible.  
     
     
         10 . The method of  claim 6  wherein said threshold temperature is 300 degrees Fahrenheit and the signal alerts such operator that brake fade is possible.  
     
     
         11 . The method of  claim 6  wherein said wheel component is a brake component and said threshold temperature is 500 degrees Fahrenheit and the signal alerts such operator of brake fade.  
     
     
         12 . The method of  claim 6  wherein said wheel component is a brake component and an estimated tire temperature is extrapolated from the measured brake temperature and said signal indicates that tire ply separation is possible.  
     
     
         13 . The method of  claim 6  wherein said wheel component is a tire and said signal indicates that tire ply separation is possible.  
     
     
         14 . A method of alerting a vehicle operator to a brake condition comprising: 
 a) measuring a thickness of a brake lining pad;    b) comparing the measured thickness of the brake lining pad to a known threshold brake lining thickness; and    c) providing a signal for such operator indicating the condition of the brake lining pad.    
     
     
         15 . The method of  claim 14  wherein measuring the thickness of the brake lining pad comprises measuring a distance from the brake lining pad to an inner surface of a brake drum, comparing the measured distance to a known initial distance from the brake lining pad to the inner surface of the brake drum and calculating the remaining brake lining pad thickness.  
     
     
         16 . The method of  claim 15  wherein the signal provided to the operator indicates remaining lining pad thickness.  
     
     
         17 . The method of  claim 15  wherein the signal provided for an operator indicates a distance the vehicle can safely travel with the remaining brake lining pad.  
     
     
         18 . The method of  claim 15  wherein the signal provided for the operator indicates that brake reline is required.  
     
     
         19 . A method of alerting a vehicle operator of brake adjustment comprising: 
 a) measuring a distance from a brake lining pad to an inner surface of a brake drum;    b) comparing the distance from the brake lining pad to the inner surface of the brake drum to a range of predetermined acceptable values; and    c) providing a signal to an operator of the vehicle indicating a need for service when the distance from the brake lining pad to the inner surface of the brake drum is outside the range of predetermined acceptable values.    
     
     
         20 . The method of  claim 19  wherein measuring the distance from the brake lining pad to the inner surface of the brake drum is accomplished by measuring relative linear motion of a brake shoe with respect to the inner surface of the brake drum when the brake shoe is moved between a disengaged position and an engaged position.  
     
     
         21 . The method of  claim 19  wherein measuring the distance from the brake lining pad to the inner surface of the brake drum comprises operably connecting a linear variable differential transformer to a brake shoe, moving said brake shoe between a disengaged position and an engaged position and measuring an electric signal produced by said transformer to determine the distance from the brake lining pad to the inner surface of the brake drum.  
     
     
         22 . A method of alerting a vehicle operator of brake imbalance comprising: 
 a) measuring a thickness of a brake lining pad of a first brake assembly;    b) measuring a thickness of a brake lining pad of a second brake assembly;    c) determining a difference in thickness between the brake lining pad of the first brake assembly and the brake lining pad of the second brake assembly;    d) comparing the difference in thickness to a predetermined threshold value; and    e) providing a signal to the vehicle operator indicating brake imbalance when the difference in thickness exceeds the predetermined threshold value.    
     
     
         23 . The method of  claim 22  wherein measuring the thicknesses of the first and pads comprises measuring a distance from each pad to a drum inner surface of each brake assembly, comparing each measured distance to a known initial distance from each brake lining pad to each drum inner surfaces and calculating the brake lining pad thicknesses.  
     
     
         24 . A method of alerting a vehicle operator of brake imbalance, a vehicle includes first and second brakes assemblies, said method comprising: 
 a) measuring a temperature of a component of the first assembly;    b) measuring a temperature of a component of the second assembly;    c) determining a difference between the measured temperatures;    d) comparing the difference to a predetermined threshold value; and    e) providing a signal for the vehicle operator indicating brake imbalance when the difference in temperature exceeds the predetermined threshold value.    
     
     
         25 . An apparatus for indicating a condition of a vehicle brake assembly, such brake assembly includes a brake shoe having an outer surface, a brake lining pad connected to such outer surface of such brake shoe and a brake drum having an inner surface surrounding such brake shoe and brake lining pad, such brake shoe and brake lining pad being movable from a disengaged position wherein such brake lining pad is spaced apart from such inner surface of such brake drum and an engaged position wherein said brake lining pad is in forcible engagement with such brake drum, said apparatus comprising: 
 a) a sensor for measuring a gap between the lining and the inner surface of the drum in the disengaged position;    b) a comparitor for comparing the measured gap to known values; and    c) an indicator in communication with said comparitor for indicating brake conditions determined by comparing the measured gap and the known values, said indicator being perceivable by a vehicle operator.    
     
     
         26 . The apparatus of  claim 25  wherein said indicator indicates brake drag when said measured gap is zero.  
     
     
         27 . The apparatus of  claim 25  wherein said indicator indicates brake lining thickness remaining.  
     
     
         28 . The apparatus of  claim 25  wherein said indicator indicates a distance capable of being safely traveled prior to brake relining.  
     
     
         29 . The apparatus of  claim 25  wherein said indicator indicates that brake relining is required.  
     
     
         30 . The apparatus of  claim 25  wherein said indicator indicates that the brake assemblies are out of adjustment.  
     
     
         31 . An apparatus for indicating a condition of a vehicle wheel assembly comprising: 
 a) a sensor coupled to said assembly for measuring a temperature of a wheel assembly component;    b) a first comparitor for comparing a measured temperature of the component to a known threshold temperature;    c) a timer for measuring a time period the measured temperature exceeds said known threshold temperature;    d) a second comparitor for comparing the measured time period to a known soak time; and    e) an indicator in communication with said first and second comparing means for indicating wheel assembly conditions determined by comparing the measured temperature and measured time to the known threshold temperature and soak time.    
     
     
         32 . The apparatus of  claim 31  wherein said wheel assembly component is a brake component and said indicator indicates that brake fade is possible when the measured temperature exceeds 300 degrees Fahrenheit for longer than the known soak time.  
     
     
         33 . The apparatus of  claim 31  wherein said wheel assembly component is a brake component and said indicator indicates brake fade when the measured brake temperature exceeds 500 degrees Fahrenheit for longer than the known soak time.  
     
     
         34 . The apparatus of  claim 31  wherein said wheel assembly component is a tire and said indicator indicates that tire ply separation is possible.  
     
     
         35 . An apparatus for indicating a condition of a vehicle brake assembly, such assembly includes a brake shoe having an outer surface, a brake lining pad connected to such outer surface of such shoe and a brake drum having an inner surface surrounding such brake shoe and brake lining pad, such shoe and pad being movable from a disengaged position wherein such brake lining pad is spaced apart from such inner surface of such drum and an engaged position wherein said pad is in forcible engagement with such drum, said apparatus comprising: 
 a) a gap measuring mechanism for measuring a gap between the lining and the drum;    b) a first comparitor for comparing the measured gap to known values;    c) a sensor coupled to said brake assembly for measuring a temperature of a brake assembly component;    d) a second comparitor for comparing a measured temperature of the brake to known threshold temperatures;    e) a timer for measuring a time period the measured temperature exceeds said known threshold value;    f) a third comparitor for comparing the measured time period to a known soak time; and    g) an indicator in communication with said first, second and third comparitors for indicating dragging brakes, brake fade, tire ply separation possible, brakes out of adjustment, brake imbalance and brake lining status.    
     
     
         36 . A method of alerting a vehicle operator to a tire condition comprising: 
 a) embedding a thermocouple in a tread of a tire;    b) measuring a temperature of said tread with said thermocouple;    c) comparing the temperature of said tread to a predetermined threshold value; and,    d) providing a signal to the vehicle operator indicating when the temperature of the tread exceeds the predetermined threshold value.    
     
     
         37 . An apparatus for indicating a condition of a vehicle tire comprising: 
 a) a thermocouple embedded in a tread of a tire;    b) a comparitor for comparing a temperature of the tread to a known safe value; and,    c) an indicator in communication with said comparitor for indicating when said temperature exceeds said known safe value.