Abstract:
A vehicle brake leakage detector installs between a vehicle brake pedal and a reference point such as a steering wheel, for testing vehicle hydraulic brake systems, and, specifically, for detecting brake fluid leaks. A brake contact at one end of the detector contacts the vehicle brake pedal and a reference end at the opposite end of the detector contacts any tangible reference location, such as a steering wheel. Force means are associated with the detector for applying force for pressurizing the vehicle brake fluid when the detector is installed. A sensor detects relative movement between the brake contact and reference end to determine whether any brake fluid leaks are present. An output source indicates whether any brake fluid leaks are detected.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This is a continuation-in-part of U.S. application Ser. No. 09/248,474, filed Feb. 11, 1999. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    This invention relates generally to an apparatus for leakage testing fluid systems, and more particularly to an arrangement and method for testing vehicle hydraulic brake systems.  
         BACKGROUND OF THE INVENTION  
         [0003]    When servicing vehicles in the field, it is very important to give the customer quick and thorough service. Quicker service is desirable for several reasons, such as that it tends to result in less expense for the service, as well as being more convenient for the customer.  
           [0004]    In certain instances, however, quick service can be more difficult, such as when servicing a brake issue. Knowing how important brakes are to the performance of the vehicle, inspections can be very time consuming in the effort to guarantee that the brakes are in peak operating condition. Of course, many brake component inspections are straightforward and can be performed quickly by the technician, such as a pad thickness check, a disc thickness inspection, etc. However, confirming that a system has no brake fluid leaks can be very time consuming. Some parts of the vehicle must be disassembled and other parts are difficult to see and reach. Even when the brake components are easily accessible, it still takes time to check the numerous pipe, hose, and banjo fitting connections.  
           [0005]    It is seen, therefore, that it would be desirable to have a device for easily detecting fluid leaks. Besides being a time saving device at the service end, such a tool could also be useful at the manufacturing facility for quality checks.  
           [0006]    Therefore, among the purposes of this invention is the provision of brake leak detection capable of testing the condition of brake fluid loss.  
           [0007]    Also a purpose of this invention is the capability of providing an accurate and straightforward leakage determination which can be easily and reliably installed.  
         SUMMARY OF THE INVENTION  
         [0008]    These purposes are achieved by the brake leak detection system and method according to the present invention, wherein the condition of the brake fluid lines can be determined before a vehicle leaves the manufacturing facility.  
           [0009]    In accordance with one embodiment of the present invention, a vehicle brake leakage testing system can be easily mounted in association with and removed from the vehicle brake pedal. The brake leakage testing system comprises a brake leak detector assembly having at least a brake contact, a spring means, an output means, and a reference end, typically opposite the brake contact.  
           [0010]    The primary advantage provided by the present invention is to detect vehicle brake fluid leaks. Even an infinitesimal fluid loss can be detected at the factory, rather than after delivery to a customer. Furthermore, the brake leak detector is easy to install and can accurately determine if any brake fluid leaks are present on a vehicle in a matter of minutes.  
           [0011]    Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims, to which reference may be had for a full understanding of the nature of the present invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    In the Drawings:  
         [0013]    [0013]FIG. 1 is a side view illustrating the vehicle brake leakage testing system in accordance with the present invention;  
         [0014]    [0014]FIG. 2 illustrates the vehicle brake leakage testing system of FIG. 1 in operation;  
         [0015]    [0015]FIG. 3 is a block diagram of the brake leak detector circuit for controlling the vehicle brake leakage testing system of FIGS. 1 and 2, and providing vehicle brake leakage indication; and  
         [0016]    [0016]FIGS. 4A and 4B show a table of test data results and the graphical representation of fluid leaks, respectively. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0017]    In accordance with the present invention, a vehicle brake leakage testing system can be easily mounted in association with and removed from the vehicle brake pedal. The brake leakage testing system comprises a brake leak detector assembly having at least a brake contact, a sensor, a force applying means, an output means, and a reference end, typically opposite the brake contact.  
         [0018]    When the brake contact is in contact with the vehicle brake pedal, the reference end is located at any tangible reference location, such as in contact with the steering wheel of the vehicle. The brake pedal of the vehicle is depressed so as to securely wedge the brake leak detector assembly between the brake pedal and the tangible reference location, and encourage the spring means to apply the necessary force for pressurizing the brake fluid. The sensor is used to detect any leaks in the brake fluid line and the output means then indicates whether any leaks are detected in the brake fluid line. The device of the present invention is used when the vehicle is not running. There is electrical power to power the device as the vehicle is in an auxiliary mode.  
         [0019]    Referring to the drawings, FIG. 1 illustrates a brake leak detector assembly  10 , in accordance with the present invention. In FIG. 1, a brake contact  12 , comprises a foot/brake pedal bracket. The brake contact  12  is positioned so as to wedge the assembly  10  between the brake pedal  14  (at the brake contact  12  end) and a reference location (such as steering wheel  16 ) at reference end  18 , as illustrated in FIG. 2.  
         [0020]    Initially, a set screw  20  associated with a sliding collar  22  is loosened. The operator then sits in the driver&#39;s seat of the stationary vehicle and confirms that the steering wheel is straight and in the correct tilt position, before starting the vehicle. The brake leak detector pedal plate  12  is placed between the brake pedal  14  and the operators foot  24 . The operator then confirms that the reference end  18  is properly positioned and the sliding collar  22  is correctly oriented. The engine is then turned off and the vehicle is placed in an auxiliary mode to provide electrical power to the assembly  10 . In a preferred embodiment of the present invention, the correct orientation for the sliding collar  22  requires the sliding collar to make contact with sensor  26 , associated with circuit box  28 , illustrated in more detail in FIG. 3.  
         [0021]    To correctly locate the reference end  18 , in a preferred embodiment of the invention, the operator depresses the brake pedal  14  while pushing downward, into the brake pedal, on the assembly  10 , facilitated by force application means, such as springs  42  and  44 , or other such means, such as a screw assembly. Chain  46  and associated swivel location  48  can be used to hold the device together when the unit is not installed. This securely positions the assembly  10  between the pedal  14  and the steering wheel  16  (or other reference location). As stated, the sliding collar  22  should abut circuit box  28 , as sensed by sensor  26  and indicated by contact indicator  30 .  
         [0022]    To measure a leak in the brake system, the system is initialized. The set screw  20  is adjusted so that spring  42  displaces sliding collar  22  against sensor  26 , thereby activating the sensor  26 . With set screw  20  loosened, brake pedal  12  can be depressed and locked to the reference end  18  and steering wheel  16 . This establishes a relative position. At this point, the spring  42  has set or defined the collar  22  against sensor  26 , SO that collar  22  is in contact with sensor  26  and set screw  20  is tightened. Now spring  44  exerts a pressure to push rod  45  associated with brake pedal  12 , maintaining the tension to push and keep pedal  12  down.  
         [0023]    Continuing with FIG. 1, if there is a brake fluid leak, the pressure on rod  45  to depress pedal  12  moves the collar  22  away from contact with sensor  26 . An associated computer or means such as circuit box  28  for outputting the brake fluid leak detection results reads this result as a brake fluid leak. If there is a brake fluid leak, the pedal  12  will depress, and this relative motion of the brake pedal is detected by the sensor  26  which loses contact with the collar  22 . If there is no brake fluid leak, rod  45  and brake pedal  12  will not move, and collar  22  will maintain contact with sensor  26 . The output computer reads this result as no brake fluid leaks.  
       EXAMPLE  
       [0024]    The brake leak detector of the present invention was utilized on a 1999 Honda Civic Si. The vehicle was raised in the air and supported on jack stands, and all four wheels were removed. The following steps were then performed on each of the four wheels. First, a two inch hose on the left front caliper bleed screw was installed. The bleed screw was opened to fill the hose with fluid. The vehicle was then started, the brake leak detector of the present invention was properly installed, and the engine shut off and the vehicle placed in an auxiliary mode. The steering wheel was then lowered to its lowest tilt position, and the brake leak detector power cord was plugged into the 12 volt outlet of the vehicle. The sliding collar was positioned up on the shaft, as discussed above in reference to FIG. 1, thereby activating the sensor  26  and turning the test system on. A wrench was then placed on the left front bleed screw and slowly opened, releasing measured amounts of fluid, as indicated in the table of FIG. 4A. The number of drops released from the end of the hose before detection of the leak by the brake leak detector were counted. After detection of the leak, the bleed screw was closed. Once the vehicle was started, each of the subsequent steps was performed ten times, on each wheel, and recorded each time for the ten trials of each wheel indicated in FIG. 4A.  
         [0025]    From the test data of ten trials shown in FIG. 4A, with the accompanying graphical representation of the test data shown in FIG. 4B, it is possible to detect amounts as low as 0.2 cc of fluid leak with the device of the present invention. On no brake is a more than 0.5 cc leak necessary before detection on average. In the table of FIG. 4A, the amount of fluid that drained from each of the left front, right front, left rear, and right rear wheels is shown in drops and cc&#39;s before detection. The leakage occurring before detection is shown for each of the four wheels, in ten trials in the table of FIG. 4A. From the test data, it appears that the closer the leak is to the master cylinder, the better the detection.  
         [0026]    In FIG. 4B, the left front wheel is indicated as  60 , the right front wheel is indicated as  62 , the left rear wheel is indicated as  64  and the right rear wheel is indicated as  66 . The results of the test trials shows that detection of brake fluid leakage is detected in an amount as low as 0.2 cc, and not greater than 0.5 cc on average. The result of the testing proves that the brake leak detector will indicate if a vehicle leaks between 0 to 3 drops of brake fluid (0 to 1.0 cc) out of the system.  
         [0027]    Circuit box  28  houses brake leak detector circuitry which is used to produce an indication of “pass” or “fail” for brake fluid in a vehicle. In the embodiment illustrated in FIGS. 1 and 2, an output light  32  is green to indicate an acceptable brake fluid system, and red to indicate an unacceptable brake fluid system, i.e., a fluid leak. An audible signal, such as buzzer  34 , can also be incorporated to give additional indication of failure mode.  
         [0028]    Referring now to FIG. 3, it will be obvious to those skilled in the art that the objective of the circuitry, to produce an indication of pass or fail for brake fluid, can be accomplished by a variety of suitable means and methods, such as, for example, an oscillator system. When the test is initiated, the circuit of box  28 , as detailed in circuit block diagram  50  specifies that timing means  52 , such as an oscillator, runs for a period of 1 minute and 5 seconds, at a minimum. This slow 1 minute pulse train goes into logic block  54 , which comprises a serial to parallel converter having two functions. First, the converter is used as a counter until 5 pulse trains pass, which approximately represents 5 minutes and 30 seconds. This also signifies the end of the test when the vehicle passes (i.e., when no brake fluid leak is detected), outputting the result at block  56 , typically in the form of a green output light  32  or buzzer  34 . Secondly, using a serial-to-parallel converter also gives five outputs, shown as five timing lights  10 , representing each minute of time.  
         [0029]    When a failure is detected, this is indicated by suitable means, such as a blocking transistor for blocking the timing clock pulse. This stops the timer and ensures the failed output stays activated. Since these five light outputs  36  can change incorrectly when failure occurs, a D-FF can be inserted as a timing light memory to help buffer switch spikes produced at the blocking transistor for the serial-to-parallel converter. This helps to prevent premature activation of the subsequent light, in light series  36 , when a failure occurs.  
         [0030]    In this embodiment, the logic  58  of the circuit  50  uses two external inputs and one internal input. The two external inputs to logic are the leak detection sensor  26  and toggle switch  40 , as seen in FIG. 3. The internal input is the output of the serial-to-parallel converter after the 5 minute interval. This goes through a series of AND and INVERTER gates in block  54  to stop the timer  52  and keep the timing lights activated when failure occurs. The opposite is also true when a pass occurs, that is, a transistor of block  54  can be activated to block the detector switch  62  in case a detected failure happens after the 5 minutes is complete. The visual reference of the test duration is indicated at block  58 .  
         [0031]    Once assembly  10  is securely and properly positioned between the brake pedal  14  and the steering wheel  16 , the vehicle is shut off, the ignition turned to accessory, and the steering wheel locked into the proper tilt position. The detector assembly  10  is plugged into the vehicle&#39;s 12-volt power outlet, using connection means  38 . At this point, the sliding collar  22  is allowed to touch sensor  26 , with the contact confirmed by contact indicator  30 . The set screw  20  should now be tightened, to maintain the sliding collar in the desired position.  
         [0032]    To initiate testing of the brake fluid condition, “test start” switch  40  is engaged, at which point the first of the series of lights  36  should turn on. If no leaks are detected, the second light  36  will come on after approximately 2 to 2½ minutes; the third light  36  will come on after approximately 3 to 3½ minutes; the fourth light  36  will come on after approximately 4 to 4½ minutes; the fifth light  36  will come on after approximately 5 to 5½ minutes; and the output light  32  will be green. Conversely, if a leak is detected, even a leak as seemingly insignificant as a single drop of fluid, audible indicator  34  will sound, output light  32  will be red, the lights  36  will stop illuminating, and contact indicator  30  will be off. In this manner, brake fluid condition for a vehicle can be quickly and accurately tested for.  
         [0033]    Hence, spring  42  operates on collar  22  when the set screw  20  is loose, positioning the face of collar  22  against sensor  26 . When collar  22  is locked into position, spring  42  is inoperable. Then, spring  44  acts on rod element  45  against the brake pedal  14 , which brake pedal  14  resists (when there is no leak), leaving collar  22  in contact with sensor  26 ; or which brake pedal  14  allows, depressing pedal  14  and moving collar  22  out of contact with sensor  26  (when there is a leak).  
         [0034]    Having described the invention in detail and by reference to the preferred embodiment thereof, it will be apparent that other modifications and variations are possible without departing from the scope of the invention defined in the appended claims.