Abstract:
A method and apparatus for filling a transmission at the transmission assembly plant including the steps of pumping fluid through the transmission entering at a first port and exiting through a second port, rotating the torque converter to purge trapped air, shifting the transmission, filling the transmission to a desired level and plugging the first and second ports. Through use of the method and apparatus of the present invention, the transmission is placed in a “road ready” condition and will not require additional fluid to be added in a top off operation at the vehicle assembly plant.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION  
       [0001]     The present invention relates to a method and apparatus to fill an automatic transmission with fluid. More particularly, the present invention relates to a fluid filling process occurring while the torque converter of the transmission is being rotated.  
         [0002]     Automatic transmissions for vehicles typically require a predetermined quantity of fluid to ensure proper operation. Various fluid filling devices and methods have been devised to fill transmissions with fluid. One method involves pumping a known-quantity of fluid into the recently assembled transmission. This method suffers from inaccuracy possibly resulting in an over-filled or under-filled transmission. Because some of the components within the transmission have already been “wetted” during previous testing, an unknown quantity of fluid is already present in the transmission.  
         [0003]     Another method includes weighing each component of the automatic transmission in a dry state and weighing an assembled automatic transmission which has been properly filled. The difference between the weights correlates to the quantity of fluid to be added. Unfortunately, this method may also be subject to undesirable over-filling or under-filling of the transmission based on component weight variation and model mix complexity.  
         [0004]     Yet another method involves filling the transmission to a predetermined level. However, at the time of first filling an automatic transmission, unknown quantities of air are trapped within the torque converter and other cavities of the automatic transmission. Therefore, the transmission may be over-filled or under-filled depending on the quantity of trapped air. Based on the variations previously described, it is common practice for the transmission assembly plant to provide the transmission in an under-filled condition to the vehicle assembly plant. At the vehicle assembly plant, the transmission is coupled to a transmission cooler and the vehicle&#39;s engine. Once these connections have been made, a final fill or “top off” operation is performed to assure that the automatic transmission has been filled to the proper level. At the vehicle assembly plant, the top off operation is costly and time consuming.  
         [0005]     Accordingly, the present invention provides a method and apparatus for properly filling a transmission at the transmission assembly plant. In particular, a method of filling a transmission with fluid is provided including the steps of pumping fluid through the transmission entering at the first port and exiting through the second port, rotating the torque converter to purge trapped air, shifting the transmission, filling the transmission to a desired level and plugging the first and second ports. Through use of the method and apparatus of the present invention, the transmission is placed in a “road ready” condition and will not require additional fluid to be added in a top off operation at the vehicle assembly plant.  
         [0006]     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0008]      FIG. 1  is a schematic view of an exemplary work station including the oil fill machine of the present invention;  
         [0009]      FIG. 2  is a side view of the work station including an exemplary transmission;  
         [0010]      FIG. 3  is a perspective view of an exemplary automatic transmission;  
         [0011]      FIG. 4  is a flow chart depicting the process of filling an automatic transmission;  
         [0012]      FIG. 5  is a fragmentary cross-sectional side view depicting a fill nozzle and an automatic transmission;  
         [0013]      FIG. 6  is a fragmentary cross-sectional side view depicting a temperature compensation tool in conjunction with an automatic transmission;  
         [0014]      FIG. 7  is a fragmentary cross-sectional side view depicting a shifter collet in conjunction with an automatic transmission; and  
         [0015]      FIG. 8  is a cross-sectional side view depicting a return nozzle in conjunction with an automatic transmission.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0016]     The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0017]     With reference to  FIGS. 1 and 2 , an exemplary automatic transmission  10  is positioned within an oil fill machine  12  constructed in accordance with the teachings of the present invention. Oil fill machine  12  is depicted as a work station  14  positioned along a conveyor  16  of an automatic transmission assembly line. Oil fill machine  12  is configured to allow transmissions to sequentially enter work station  14 , be filled with fluid and exit the work station once the fill process of the present invention has been completed.  
         [0018]     Work station  14  includes a gantry frame  18  supporting overhead tooling including a fill nozzle  20 , a shifter collet  22 , a temperature compensation tool  24  and a dipstick plug tool  26 . A drive unit  28 , a return nozzle  30 , and a cooler fitting tool  32  are also positioned within work station  14  and may be coupled to gantry frame  18 .  
         [0019]     As mentioned earlier, oil fill machine  12  functions to accurately fill automatic transmission  10  with fluid such that a subsequent top off filling operation is not required at the vehicle assembly plant. To achieve this goal, drive unit  28  rotates a torque converter  34  of transmission  10  while fluid is pumped through the automatic transmission. Specifically, fluid is stored in a tank  36  having a motor  38  and a pump  40  coupled thereto. Fluid may be selectively dispensed through fill nozzle  20  by opening a combination of three inlet valves. A fast fill valve  42  provides substantially unrestricted flow from pump  40  to nozzle  20 . A slow fill valve  44  is plumbed in series with an orifice  46 . Orifice  46  reduces the flow through fill nozzle  20  and allows for more accurate control of the final fill level as will be described in greater detail hereinafter. A nozzle valve  47  is located within fill nozzle  20 . Nozzle valve  47  receives fluid allowed to pass by fast fill valve  42  and/or slow fill valve  44 .  
         [0020]     With reference to  FIG. 3 , automatic transmission  10  includes a housing  48  having a dipstick aperture  50 , a temperature compensation aperture  52 , a cooler fitting aperture  54  and a shifter aperture  56 .  
         [0021]     To purge air trapped within cavities of torque converter  34  and transmission housing  48 , drive unit  28  is operable to selectively engage torque converter  34  and rotate the torque converter during filling. During the filling operation, fill nozzle  20  enters dipstick aperture  50  and return nozzle  30  enters cooler fitting aperture  54  to define the path of fluid flow during the filling operation. Station and tank exit valves  58  and  59 , respectively, are plumbed in line between return nozzle  30  and tank  36  to selectively restrict the flow through transmission  10 .  
         [0022]     Drive unit  28  includes a spindle  60  having a plurality of drive lugs  62  axially extending therefrom. A vacuum cup  64  is fixed to spindle  60 . Vacuum cup  64  includes an outer lip  66  for selective engagement with torque converter  34 . An aperture  68  extends through vacuum cup  64  and is in communication with a vacuum source (not shown). Spindle  60  is rotatably mounted to a support  70 . Support  70 , as well as spindle  60 , are axially moveable along a slide  72  to provide a method for selectively engaging drive lugs  62  and vacuum cup  64  with torque converter  34 .  
         [0023]     With reference to  FIG. 4 , a process of filling automatic transmission  10  will be described. It should be appreciated that prior to entering work station  14 , transmission  10  is mounted to a pallet  74 . Pallet  74  travels along conveyor  16  from station to station during the assembly process.  
         [0024]     At step  100 , pallet  74  enters work station  14 . At step  102 , pallet clamps  76  engage pallet  74  to fix the position of transmission  10  with oil fill machine  12 . Additionally, cooler fitting tool  32  advances toward a bank of cooler fittings. One cooler fitting is fed toward and coupled to cooler fitting tool  32 .  
         [0025]     At step  104 , drive unit  28  is advanced to engage drive lugs  62  with torque converter  34 . Outer lip  66  of vacuum cup  64  also engages torque converter  34 . Also, fill nozzle  20  is advanced to engage dipstick aperture  50 .  
         [0026]     As shown in  FIG. 5 , fill nozzle  20  includes a supply tube  105  and a depth gage  106 . Depth gage  106  includes a bubbler transducer which measures the pressure head generated at an end face  108  of depth gage  106 . The bubbler transducer is calibrated to provide a signal equivalent to fluid depth in millimeters. To define a datum plane from which to measure fluid depth, end face  108  is inserted a predetermined distance from a land  110  of transmission housing  48 . As such, end face  108  defines a plane  112  from which fluid depth measurements are taken. Line  114  represents 15 mm of fluid depth. Line  116  represents 19 mm of fluid depth and line  118  represents 30 mm of fluid depth above end face  108 . Fast fill valve  42 , slow fill valve  44 , nozzle valve  47 , station exit valve  58 , tank exit valve  59  and depth gage  106  are in communication with a controller  121 . Controller  121  actuates the fill valves and the exit valves based on feedback provided by depth gage  106  to maintain a desired fluid level.  
         [0027]     Fill nozzle  20  and depth gage  106  are mounted on a slide  120 . An actuator  122  is mounted to gantry frame  18  and is controllable to selectively raise and lower slide  120  and fill nozzle  20 . One skilled in art will appreciate that actuator  122  may include any number of mechanical operators such as electric motors, hydraulic pistons, gear transfer mechanisms, chain drive mechanisms and the like. Actuator  122  may also be coupled to a positioning mechanism (not shown) to move actuator  122  within the space defined by gantry frame  18 .  
         [0028]     Step  104  also includes advancing temperature compensation tool  24  as shown in  FIG. 6 . Temperature compensation tool  24  includes a 12-pin receptacle  124  coupled to a slide  126  operable to raise and lower 12-pin receptacle  124  in to and out of communication with a 12-pin connector  128 . 12-pin connector  128  was mounted within transmission  10  prior to the transmission&#39;s arrival within work station  14 . 12-pin connector  128  is in communication with a thermocouple mounted within transmission housing  48 . Accordingly, temperature compensation tool  24  operates to communicate a signal indicative of the fluid temperature to controller  121  to provide the controller with fluid temperature data during the filling operation. Because the density of the fluid used in the automatic transmission changes with temperature, monitoring of the fluid temperature during filling improves fill accuracy. Controller  121  adjusts the final fill height to account for the volumetric change due to changes in temperature.  
         [0029]     At step  130 , dipstick plug tool  26 , which was advanced at step  104 , picks up a dipstick plug. At step  132 , shifter collet  22  is advanced as shown in  FIG. 7 . Shifter collet  22  includes a sleeve  134  which is selectively engageable with a shifter shaft  136 . Rotation of shifter shaft  136  causes transmission  10  to shift through the available gear ratios. An encoder  137  communicates the rotational position of sleeve  134  to controller  121 . Shifter collet  22  includes a slide  138  coupled to gantry frame  18  for raising and lowering shifter collet  22  in to and out of engagement with shifter shaft  136 . Shifter collet  22  also includes an actuator  140  for incrementally rotating shifter shaft  136 . It is contemplated that shifter collet  22  may be moved from side to side within gantry frame  18  as well as in a vertical manner as previously described. At step  142  transmission  10  is shifted into park.  
         [0030]     At step  144 , vacuum is supplied through aperture  68  to axially displace torque converter  34  toward drive unit  28 . This operation properly positions torque converter  34  relative to the internal fluid passageways within automatic transmission  10 . At step  146 , return nozzle  30  is advanced into engagement with cooler fitting aperture  54  as shown in  FIG. 8 . At this time, a complete fluid circuit from tank  36  through fill nozzle  20 , automatic transmission  10 , return nozzle  30  and back to tank  36  is defined. Return nozzle  30  includes station exit valve  58  and a pressure transducer  147 . Pressure transducer  147  provides a signal indicative of the fluid pressure exiting the transmission through return nozzle  30 . Return nozzle  30  is mounted to a slide  149  which allows the return nozzle to move between the advanced position engaged with cooler fitting aperture  54  and a retracted position disengaged from the transmission.  
         [0031]     At step  148 , a retaining arm restricting rotation of torque converter  34  is disengaged to allow the torque converter to rotate. At step  150 , nozzle valve  47 , fast fill valve  42  and slow fill valve  44  are opened. Step  152  defines filling the transmission to a depth of 15 mm represented by line  114  in  FIG. 5 . Once the 15 mm depth has been met, station exit valve  58  is opened at step  154  to allow fluid to flow through transmission  10 . Tank exit valve  59  remains closed to create a back pressure within transmission  10 . Fast fill valve  42 , slow fill valve  44  and nozzle valve  47  are controlled to assure that a depth of at least 15 mm is maintained throughout the remaining steps.  
         [0032]     At step  156 , drive unit  28  causes torque converter  34  to begin to rotate. Drive unit  28  maintains the torque converter speed at a predetermined value such as 1800 rpm. The 15 mm depth corresponds to a minimum sump level which is maintained to assure that additional air is not pumped into the system.  
         [0033]     At step  158 , shifter collet  22  rotates shifter shaft  136  to cause the transmission to shift gears. Preferably, the transmission will be operated for two seconds in each of the available gears including park, reverse, neutral, drive and any ancillary gear settings. By sweeping through the gears, each of the hydraulic servos associated with the internal clutches of the transmission are actuated to fill their respective servo chambers.  
         [0034]     Torque converter rotation is stopped at step  160 . The torque converter is stopped to allow the transmission to be shifted into park at step  162 .  
         [0035]     After the transmission has been shifted into park, drive unit  28  rotates torque converter  34  at 1800 rpm as depicted in step  164 . Pressure transducer  147  provides a signal indicative of the fluid pressure exiting the transmission. Once pressure transducer  147  indicates that a pressure of 20 psig has been reached, tank exit valve  59  is opened at step  166 . Next, the transmission is purged of air as depicted at step  170 . During the purging cycle, station and tank exit valves  58  and  59  as well as fast fill valve  42 , slow fill valve  44  and nozzle valve  47  are controlled to maintain a fluid depth of 30 mm.  
         [0036]     After the air has been purged from the transmission, fast fill valve  42  and slow fill valve  44  are closed at step  172 . At step  174 , fluid is allowed to drain into tank  36 . Once the fluid level has been below the 19 mm line for one second, station and tank exit valves  58  and  59  are closed at step  176 .  
         [0037]     At step  178 , slow fill valve  44  is opened to begin the final filling portion of the process. Line  116  is offset a distance of 19 mm from end face  108  of depth gage  106 . The 19 mm line represents a nominal target fill level. This target fill level incorporates an excess volume of fluid which will fill the lines interconnecting transmission  10  and the transmission fluid cooler mounted on the vehicle. Furthermore, the 19 mm line is a nominal target that controller  121  uses as a starting point to determine the final fill depth. Based on the temperature/viscosity curve of the fluid and the fluid temperature as relayed by temperature compensation tool  24 , an adjusted final fill depth is calculated at step  180 .  
         [0038]     At step  182 , fluid is allowed to pass through slow fill valve  44  and orifice  46  until the adjusted fill level is met. At step  184 , slow fill valve  44  is closed. At step  186 , drive unit  28  is instructed to stop rotating torque converter  34 . Once torque converter  34  has stopped rotating, shifter collet  22  shifts the transmission into the vehicle assembler&#39;s desired gear position at step  188 . For example, some manufacturers wish to have the transmission placed in neutral while others desire to have the transmission placed in park prior to assembly within the vehicle.  
         [0039]     At step  190 , fill nozzle  20  and return nozzle  30  are retracted away from the transmission. At step  192 , dipstick plug tool  26  advances and inserts the dipstick plug. At step  194 , cooler fitting tool  32  advances and installs a cooler fitting plug. After the plugs have been installed, dipstick plug tool  26  and cooler fitting tool  32  retract away from transmission  10 .  
         [0040]     At step  196 , the retaining arm which was previously disengaged from the torque converter is now allowed to engage the torque converter. At step  198 , vacuum is no longer supplied through aperture  68  and lip  66  is disengaged from torque converter  34 . At step  200 , support  70  and spindle  60  are retracted along slide  72  to disengage lugs  62  from torque converter  34 . Pallet clamps  76  disengage pallet  74  at step  202 . Pallet  74  and automatic transmission  10  exit oil fill machine  12  and work station  14 .  
         [0041]     Furthermore, the foregoing discussion disclosed and describes merely exemplary embodiments of the present invention. For example, the temperature compensation tool and the fill nozzle may be mounted on a singular slide and moved by a single actuator. Additionally, the amount of fluid present within the automatic transmission may be determined by any number of devices including sight gages, dipsticks, capillary tubes and the like, without departing from the scope of the present invention. Also, one skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that various changes, modifications and variations may be made therein without department from the spirit and scope of the invention as defined in the following claims.