Abstract:
A system for determining the type of hydraulic fluid employed in a transmission includes a translating valve, a valve position sensor, a hydraulic fluid temperature sensor, and a controller. The valve position sensor is operable to measure the actual time the valve takes to translate within the hydraulic fluid. The controller is operable to compare the actual time of valve translation to an expected time of valve translation. If the actual time of valve translation is different than the expected time of valve translation to a predetermined degree, the controller is operable to signal an operator of the motor vehicle or a service technician that the hydraulic fluid being used in the transmission is not meeting operating expectations.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/051,799, filed on May 9, 2008. The disclosure of the above application is incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The invention relates generally to a hydraulic fluid determination system and method for a motor vehicle, and more particularly to a hydraulic fluid determination system and method having a translatable valve and a controller operable to determine the type of hydraulic fluid in a transmission. 
       BACKGROUND 
       [0003]    The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art. 
         [0004]    A typical automatic transmission employs a hydraulic fluid, such as an oil, to provide lubrication to various transmission components, to provide cooling, and to actuate valves, solenoids, and/or pistons within a hydraulic control system. Various types of hydraulic fluids or oils have specific properties tailored to their intended use. For example, engine oils are intended to be employed in an engine of a motor vehicle while transmission oils are intended to be employed in the transmission of the motor vehicle. These transmission oils are compatible with the components of the transmission and allow the transmission to operate as intended. 
         [0005]    However, it is possible that a hydraulic fluid not specified by the transmission may be employed by an operator of the motor vehicle or a service technician. If a hydraulic fluid that is not intended to be used by the transmission is employed, the transmission components may wear more quickly, shift quality can degrade, and the hydraulic fluid life can degrade more quickly than expected. Accordingly, there is room in the art for a system integrated in the motor vehicle that determines if a hydraulic fluid is being employed by the transmission that is not compatible with the transmission. 
       SUMMARY 
       [0006]    The present invention provides a system for determining the type of hydraulic fluid employed in a transmission. The system includes a translating valve, a valve position sensor, a hydraulic fluid temperature sensor, and a controller. The valve position sensor is operable to measure the actual time the valve takes to translate within the hydraulic fluid. The controller is operable to compare the actual time of valve translation to an expected time of valve translation. If the actual time of valve translation is different than the expected time of valve translation to a predetermined degree, the controller is operable to signal an operator of the motor vehicle or a service technician that the hydraulic fluid being used in the transmission is not meeting operating expectations. 
         [0007]    Further objects, aspects and advantages of the present invention will become apparent by reference to the following description and appended drawings wherein like reference numbers refer to the same component, element or feature. 
     
    
     
       DRAWINGS 
         [0008]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
           [0009]      FIG. 1  is a schematic diagram of an embodiment of a hydraulic fluid determination system according to the principles of the present invention; and 
           [0010]      FIG. 2  is a flow chart of an embodiment of a method of determining the type of a hydraulic fluid using the hydraulic determination system of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
         [0012]    With reference to  FIG. 1 , a hydraulic fluid determination system for use in a motor vehicle is generally indicated by reference number  10 . The hydraulic fluid determination system  10  is operable to determine a type of a hydraulic fluid  12  employed in an exemplary transmission  14 , as will be described in further detail below. The transmission  14  may have various configurations without departing from the scope of the present invention. The hydraulic fluid determination system  10  includes a valve assembly  16 , a valve position sensor  18 , a temperature sensor  19 , a controller  20 , and a diagnostic display  22 . 
         [0013]    The valve assembly  16  generally includes a valve  24  disposed within a valve body  26 . The valve  24  is translatable or slidable within the valve body  26  between at least two positions. The valve  24  is in fluid communication with the hydraulic fluid  12 . In the present embodiment, the valve assembly  16  is part of a hydraulic control system  28  within the transmission  14 , however, it should be appreciated that the valve assembly  16  may be located within various other subsystems of the transmission  14  without departing from the scope of the present invention. Moreover, the configuration of the valve assembly  16  may vary without departing from the scope of the present invention so long as the valve assembly  16  includes a component in fluid communication with the hydraulic fluid  12  that is moveable between at least two positions. 
         [0014]    The valve position sensor  18  is in communication with the valve assembly  16  and is operable to determine the position of the valve  24  within the valve assembly  16 . The valve position sensor  18  is preferably a pressure switch located within the hydraulic control system  28  that selectively receives a pressurized hydraulic fluid flow when the valve  24  is in at least one of the two positions. Accordingly, receipt of the pressurized hydraulic fluid flow by the valve position sensor  18  is indicative of the position of the valve  24 . However, it should be appreciated that the valve position sensor  18  may take various other forms without departing from the scope of the present invention. For example, the valve position sensor  18  may be an electromechanical switch or other kind of sensor. 
         [0015]    The temperature sensor  19  is in communication with the hydraulic fluid  12  and is operable to sense the temperature of the hydraulic fluid  12  within the transmission  14 . The temperature sensor  19  may take various forms without departing from the scope of the present invention. 
         [0016]    The controller  20  is, for example, a transmission controller, a vehicle control module, or other electronic device having a preprogrammed digital computer or processor, control logic, memory used to store data, and at least one I/O peripheral. However, other types of controllers may be employed without departing from the scope of the present invention. The controller  20  is in communication with the hydraulic control system  28  of the transmission  14 , with the valve position sensor  18 , and with the temperature sensor  19 . More specifically, the controller  20  is configured to receive data signals from the valve position sensor  18  indicative of the position of the valve  24 , to receive data signals from the temperature sensor  19  indicative of the temperature of the hydraulic fluid  12 , and to send control signals to the hydraulic control system  28 . 
         [0017]    The diagnostic display  22  is in communication with the controller  20 . The diagnostic display  22  is operable to communicate the type of hydraulic fluid  12  within the transmission  14  to an operator or service technician of the motor vehicle. For example, the diagnostic display  22  may be a warning light or digital message displayed on the instrument panel of the motor vehicle or a diagnostic device connected to the controller  20  during maintenance. Moreover, the diagnostic display  22  can be configured to indicate that a more frequent transmission hydraulic fluid change is needed if the hydraulic fluid  12  is determined to be a type not intended for the transmission  14 . 
         [0018]    Turning now to  FIG. 2  and with continued reference to  FIG. 1 , a method of determining the type of the hydraulic fluid  12  using the hydraulic fluid determination system  10  is generally indicated by reference number  100 . The method  100  begins when the valve  24  is translated or moved at step  102 . The valve  24  may be translated during normal operation of the transmission  14  or by a specific command from the controller  20  to the hydraulic control system  28 . 
         [0019]    At step  104  the valve position sensor  18  senses when the valve  24  has completed the translation from the first position to the second position. A data signal indicative of completion of the translation of the valve  24  is communicated to the controller  20 . At step  106 , the controller  20  determines an actual time of valve translation by comparing the time when the valve  24  began to translate at step  102  to the time the valve  24  finished translating as indicated by the valve position sensor  18 . The actual time of valve translation is dependent on what type of hydraulic fluid is in communication with the valve  24  and the temperature of the hydraulic fluid. More specifically, for a given temperature, a hydraulic fluid with high viscosity will cause the valve  24  to move more slowly than a hydraulic fluid with low viscosity. At step  108  the temperature sensor  19  senses the temperature of the hydraulic fluid  12 . A data signal indicative of the temperature of the hydraulic fluid  12  is communicated to the controller  20 . 
         [0020]    At step  110  the controller  20  compares the actual valve translation time determined at step  106  to an expected valve translation time to determine a time difference value. The expected valve translation time is the amount of time the valve  24  is expected to take to translate from the first position to the second position when a type of hydraulic fluid that is compatible with the transmission  14  having a temperature equal to the sensed temperature of the hydraulic fluid  12  is employed. The time difference value is the time difference between the actual valve translation time and the expected valve translation time. 
         [0021]    At step  112  the controller  20  compares the time difference value determined at step  110  to a threshold value. The threshold value is a predetermined value set at a limit where it is desirable to indicate to the operator of the motor vehicle or a service technician that the hydraulic fluid  12  is not compatible with the transmission  14 . Moreover, various thresholds may be employed, each indicative of a type of hydraulic fluid, such that exceeding a certain threshold or falling within a range of thresholds indicates a certain type of hydraulic fluid within the transmission. 
         [0022]    If the time difference value exceeds the threshold value, the method  100  proceeds to step  114  and the controller  20  communicates to the diagnostic display  22  that there is an issue with the hydraulic fluid  12  within the transmission  14 . As noted above, this may include reducing the time between scheduled oil changes or indicating that the hydraulic fluid  12  should be changed as soon as possible. Additionally, this information may be stored in the controller until the information is requested during a maintenance check. If the time difference value does not exceed the threshold value, the method  100  returns to step  102  and repeats, thereby providing a real-time and updated check of the status of the hydraulic fluid  12 . 
         [0023]    The description of the invention is merely exemplary in nature and variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.