Abstract:
An apparatus and method for repairing an automatic transmission. Access is obtained to the valve body and a special shaped Torque Converter Clutch (TCC) regulator apply valve clip is inserted against a TCC regulator apply valve to hold a TCC regulator apply valve in a fully open position. The clip is dished to avoid wear when engaging the TCC regulator apply valve and has an asymmetric top portion which cooperates with the shape of the valve body chamber the TCC regulator apply valve clip is inserted into, to ensure proper placement.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to the repair of automatic transmissions and in particular to a simple method using a low cost clip to repair an automatic transmission by limiting the movement of a Torque Converter Clutch (TCC) regulator apply valve in General Motors 4L60E, 4L65E, and 4L70E automatic transmissions. 
     TCCs are incorporated into automatic transmissions to lock a torque converter to provide better efficiency. During unlocked operation, for example, at startup, the torque convert provides torque multiplication and smooths impulses from the engine. Unfortunately, torque converters reduce overall power train efficiency by about ten percent. At higher speeds, the torque multiplication and smoothness is not required, and the TCC may be applied to directly couple the torque converter input from the engine to the automatic transmission, thereby eliminating the inefficiency otherwise experienced. 
     A TCC oil circuit controls flows and pressures of oil between the TCC valve and the torque converter. Known TCC operation is described as follows. When operating conditions for engaging the TCC are met, a Powertrain Control Module (PCM) energizes the TCC on-off solenoid. Energizing the TCC on-off solenoid causes the TCC on-off solenoid to close, shifting the TCC valve, thereby switching fluid connections in the TCC valve. Switching the fluid connections in the TCC valve results in pressure being released in the converter release circuit and converter release oil exhausting at the converter clutch valve down through check ball # 9  on the end of the torque converter turbine shaft (sometimes called “input shaft”). Simultaneously, a regulator apply circuit is connected to a converter apply circuit pressure equal to the pressure in the regulator apply circuit. The oil pressure in the oil circuit is applied to a converter lockup apply piston in the torque converter to lock the TCC. 
     Pressure regulation in the regulator apply circuit is controlled as described in the following. An actuator feed limit valve regulates pressure in a pressure regulated circuit. The pressure regulated circuit is further regulated by a TCC Pulse Width Modulator (PWM) regulator solenoid. Pressure in the pressure regulator circuit pushes the isolator valve into the TCC regulator apply valve opening the TCC regulator apply valve to increase pressure to the desired oil pressure level. 
     Unfortunately, wear occurs in the TCC regulator apply valve  24  and isolator valve  25  body bores due to an oscillation inherent to the operation of the TCC PWM regulator solenoid acting on the TCC regulator and isolator valve. The wear results in a lower than required pressure in the converter apply circuit  20   d . The TCC PWM regulator solenoid is unable to compensate for reduced pressure, and additional leaking resulting from the wear, which results in the TCC slipping too much. A code 1870 (trans component slipping) results. The TCC slip code is then stored in the transmission computer causing the malfunction indicator lamp to light up on the dashboard. The code and resulting check engine light or malfunction indicator light keeps the vehicle from being registered in most US states making repairs necessary. Generally, the automatic transmission is repaired by replacing the valve body at a cost of $300.00 dollars or more, by using fixtures to ream out and use oversize valves, or by a tedious and time consuming process of using different shims selected to fit the four or more different types of original equipment valves and other aftermarket valves. A less expensive method of repairing the common failure is needed. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention addresses the above and other needs by providing an apparatus and method for repairing an automatic transmission. Access is obtained to the valve body and a special shaped Torque Converter Clutch (TCC) regulator apply valve clip is inserted against a TCC regulator apply valve to hold a TCC regulator apply valve in a fully open position. The clip is dished to avoid wear when engaging the TCC regulator apply valve and has an asymmetric top portion which cooperates with the shape of the valve body chamber the TCC regulator apply valve clip is inserted into, to ensure proper placement. 
     In accordance with one aspect of the invention, there is provided a method for repairing an automatic transmission. The method includes removing an automatic transmission oil sump pan from the automatic transmission, removing a valve body exposed by removing the oil sump pan from the automatic transmission and separating the valve body from a separator plate, positioning a Torque Converter Clutch (TCC) regulator valve in an open position, inserting a TCC regulator apply valve clip into an open chamber of the valve body to engage the spool area of the TCC regulator apply valve with a convex dished side of the TCC regulator apply valve clip extending in the opening direction of the TCC regulator apply valve, reinstalling the valve body and separator plate, and reinstalling the automatic transmission oil sump pan. The TCC regulator apply valve is positioned in the open chamber to align a spool area of the TCC regulator apply valve with the open chamber of the valve body and TCC regulator apply valve clip is inserted into the open chamber of the valve body to engage the spool area of the TCC regulator apply valve with an elongated portion of the TCC regulator apply valve clip facing away from a proximal end of the open chamber. The TCC regulator apply valve clip thus allows the blocking of the TCC regulator apply valve in the open position without the removal of the TCC regulator apply valve from the valve body. 
     Installation of the TCC regulator apply valve clip according to the present invention causes the oil pressure in the regulator apply circuit to be equal to pump line pressure because the TCC PWM regulator solenoid no longer regulates the pressure in the regulator apply circuit to be less than the pump line pressure. Insertion of the TCC regulator apply valve clip holds the TCC regulator apply valve open in the full apply position and is no longer affected by computer commands from the Powertrain Control Module (PCM) and wear of the isolator valve no longer reduces pressure in the regulator apply circuit. Pressure in the converter apply circuit is then controlled by the TCC on-off solenoid only, resulting in slightly firmer, but acceptable, TCC engagement. Significantly, the code 1870 (transmission component slipping) is corrected without costly repairs. 
     In accordance with another aspect of the invention, there is provided a TCC regulator apply valve clip which works on a variety of TCC regulator apply valve designs thus requiring stocking only a single part for TCC regulator apply valve repairs. 
     In accordance with yet another aspect of the invention, there is provided a method for repairing the TCC regulator apply valve using the TCC regulator clip which blocks the TCC regulator apply valve the open position and does not require removal of the TCC regulator apply valve. The TCC regulator apply valve is moved to the open position and the TCC regulator clip is then inserted, thereby saving substantial time and cost in transmission repair. 
     In accordance with yet another aspect of the invention, there is provided a TCC regulator apply valve clip having a design which does not damage the valve body by raising a burr on the TCC regulator apply valve or on the TCC regulator apply valve bore. The TCC regulator apply valve clip is convexly dished to one side. The convex dish resides against a side of a land of the TCC regulator apply valve to hold the TCC regulator apply valve in the open position while avoiding contact between the TCC regulator apply valve clip and a cylindrical surface of the lands of the TCC regulator apply valve or the TCC regulator apply valve bore. 
     In accordance with yet another aspect of the invention, there is provided a TCC regulator apply valve clip which cannot be installed backwards. Because of an asymmetric top portion, the TCC regulator apply valve clip installs without possibility of wrong installation. 
     In accordance with yet another aspect of the invention, there is provided a TCC regulator apply valve clip which is installed under a valve body separator plate and cannot become dislodged once installed. 
     In accordance with yet another aspect of the invention, there is provided a permanent repair for a worn TCC regulator apply valve. Repairing the TCC regulator value by inserting the TCC regulator apply valve clip is a permanent repair because future wear of the TCC regulator apply valve is prevented, unlike installing a new valve body or reamed out valve bodies may experience the same failure in 70,000 miles. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       The above and other aspects, features and advantages of the present invention will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings wherein: 
         FIG. 1  is a Torque Converter Clutch (TCC) oil circuit diagram in a TCC applied position. 
         FIG. 2  is a valve body of the automatic transmission with a TCC regulator valve clip according to the present invention holding a TCC regulator apply valve in the open position. 
         FIG. 2A  is a more detailed view of portion  2 A of the valve body showing the TCC regulator apply valve clip according to the present invention holding the TCC regulator apply valve in the open position. 
         FIG. 3A  is a front view of the TCC regulator apply valve clip according to the present invention. 
         FIG. 3B  is a right side view of the TCC regulator apply valve clip according to the present invention. 
         FIG. 3C  is a front view of a second embodiment of a TCC regulator apply valve clip according to the present invention. 
         FIG. 3D  is a right side view of an embodiment of the TCC regulator apply valve clip with one leg reaching forward according to the present invention. 
         FIG. 4  is a cross-sectional view taken along line  4 - 4  of  FIG. 2A  of the TCC regulator apply valve clip according to the present invention in a chamber of the valve body engaging the TCC regulator apply valve. 
         FIG. 5  is a cross-sectional view taken along line  5 - 5  of  FIG. 4  of the TCC regulator apply valve clip according to the present invention in the chamber of the valve body engaging the TCC regulator apply valve. 
         FIG. 6  is a method according to the present invention for repairing an automatic transmission. 
     
    
    
     Corresponding reference characters indicate corresponding components throughout the several views of the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description is of the best mode presently contemplated for carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of describing one or more preferred embodiments of the invention. The scope of the invention should be determined with reference to the claims. 
     A Torque Converter Clutch (TCC) oil circuit diagram  10  in a TCC applied position is shown in  FIG. 1 . Transmission fluid  20   a  is drawn from an automatic transmission oil sump pan  16  and through a filter  18  by a pump  14 . The fluid is circulated through the transmission in various flows  20   a - 20   k  to control the operation of the automatic transmission. Various exhaust points  21  are provided to release fluid to reduce pressure in selected ones the flows  20   a - 20   k . A pump flow  20   b  at pump line pressure from the pump  14  is carried to a pressure relief valve  22 , to a boost valve pressure regulator  38 , a Torque Converter Clutch (TCC) regulator apply valve  24 , and an actuator feed limit valve  32 . The boost valve pressure regulator  38  controls a boost valve flow  20   k  to a TCC valve  36 . The boost valve pressure regulator  38  is controlled by rev input flows  20   h.    
     The actuator feed limit valve  32  limits the pressure in a pressure regulated circuit  20   f  from the actuator feed limit valve  32  to a TCC Pulse Width Modulation (PWM) solenoid  26  and to a pressure control solenoid  28 . The pressure regulated circuit  20   f , subject to modulation by the TCC PWM solenoid  26 , controls an isolator valve  25  to control the position of the TCC regulator apply valve  24 . Unfortunately, rapid motion of the isolator valve  25  caused by the modulation of the TCC PWM solenoid  26  causes wear and ultimately failure of the isolator valve  25 . 
     The TCC regulator apply valve  24  controls the pressure of a regulator apply circuit  20   e  connecting the TCC regulator apply valve  24  to the TCC valve  36 . The TCC valve  36  is controlled by a TCC on-off solenoid  30  which is controlled by a Powertrain Control Module (PCM) (not shown) to apply and release the TCC. The pressure of the circuit  20   e  is normally controlled by the TCC regulator apply valve  24  to regulate the pressure in a converter apply circuit  20   d  to the torque converter  12  which in turn controls applying the TCC. 
     A valve body  40  of the automatic transmission with a TCC regulator apply valve  24  is shown in  FIG. 2  and a more detailed view of a portion  2 A of the valve body  40  showing a TCC regulator apply valve clip  46  according to the present invention, holding the TCC regulator apply valve  24  open, is shown in  FIG. 2A . The TCC regulator apply valve clip  46  resides in a chamber (or passage)  42  of the valve body  40 . The TCC regulator apply valve clip  46  is positioned over the TCC regulator apply valve  24  to restrict motion of the TCC regulator apply valve  24  to maintain the TCC regulator apply valve  24  in an open position to provide full pump line pressure through the regulator apply circuit  20   e  to the TCC valve  36  at all times to overcome wear of the isolator valve  25 . The TCC regulator apply valve clip  46  is inserted into the chamber  42  so that an asymmetrical top portion  46   a  (see  FIG. 3A ) of the TCC regulator apply valve clip  46  is pointed away from the proximal wall  42   a  of the chamber  42 . 
     A front view of the TCC regulator apply valve clip  46  according to the present invention is shown in  FIG. 3A  and a right side view of the TCC regulator apply valve clip  46  is shown in  FIG. 3B . The TCC regulator apply valve clip  46  has a height H, a top portion  46   a  width W 1 , and center portion  46   b  inside width W 2 , and a bottom portion  46   c  width W 3 . A vertical center line CL is centered on the center portion of the TCC regulator apply valve clip  46 . The top portion  46   a  is laterally asymmetric and is offset on a left side of the center line CL by an offset OS. The TCC regulator apply valve clip  46  is also a dish  47  dished a distance D to the left when viewed from the right side. The height H is preferably between 0.945 inches and 1.155 inches and more preferably approximately 1.05 inches. The TCC regulator apply valve clip  46  preferably includes two legs  47   a  and  47   b.    
     The width W 1  is preferably between 0.625 inches and 0.69 inches and more preferably approximately 0.658 inches. The inside width W 2  is preferable approximately 0.14 inches and is selected to provide a friction fit between the TCC regulator apply valve clip  46  center portion  46   b  and the spool area  24   a  (see  FIG. 5 ) so that the TCC regulator apply valve clip  46  will not fall out of the valve body  40  during reassembly of the automatic transmission. The width W 3  is preferably between 0.29 inches and 0.36 inches and more preferably approximately 0.305 inches, and the offset OS is preferably approximately 0.45 inches. The dish distance D is preferably between 0.0225 inches and 0.0275 inches and more preferably approximately 0.025 inches. 
     A front view of a second embodiment of a TCC regulator apply valve clip  46 ′ according to the present invention is shown in  FIG. 3C . The TCC regulator apply valve clip  46 ′ is similar to the TCC regulator apply valve clip  46 , except does not include the asymmetric top portion  46   a  of the TCC regulator apply valve clip  46  and has a top portion width W 2 ′ approximately equal to the bottom portion width W 3 . As a result, a mechanic installing the TCC regulator apply valve clip  46 ′ must ensure that the dish  47  is facing in the side  24   c  of the land  24   b  of the TCC regulator apply valve  24 . 
     A right side view of an embodiment of the TCC regulator apply valve clip with the leg  47   a  reaching forward ahead of the leg  47   b  is shown in  FIG. 3D . 
     The TCC regulator apply valve clips  46  and  46 ′ are preferably made from wire and more preferably from music wire, which wire is preferably between 0.030 and 0.078 inches in diameter and most preferably approximately 0.048 inches in diameter. The clip may alternative be a stamped part having the same height, overall width, and dish as the TCC regulator apply valve clips  46  and  46 ′ described above, with a vertical channel in the bottom portion and middle portion with an inside width W 2 . 
     A cross-sectional view taken along line  4 - 4  of  FIG. 2A  of the TCC regulator apply valve clip  46  according to the present invention in the chamber  42  of the valve body  40  engaging the TCC regulator apply valve  24  is shown in  FIG. 4  and a cross-sectional view taken along line  5 - 5  of  FIG. 4  of the TCC regulator apply valve clip  46  in the chamber  42  of the valve body engaging the TCC regulator apply valve  24  is shown in  FIG. 5 . A spool area  24   a  of the TCC regulator apply valve  24  is engaged by center portion of the TCC regulator apply valve clip  46  and the dish  47  (see  FIG. 3B ) resides against a side  24   c  of a land  24   b  of the TCC regulator apply valve  24  holding the TCC regulator apply valve  24  in the open position to provide full pump line pressure to the regulator apply circuit  20   e  (see  FIG. 1 ). The offset top portion of the TCC regulator apply valve clip  46  prevents installing the TCC regulator apply valve clip  46  backward and a valve body separator plate  40   a  retains the TCC regulator apply valve clip  46  in place. The convex dish  47  resides against a side  24   c  of the land  24   b  of the TCC regulator apply valve  24  to hold the TCC regulator apply valve  24  in the open position while avoiding contact between the TCC regulator apply valve clip  46  and a cylindrical surface  24   d  of the lands  24   b  of the TCC regulator apply valve  24  or a TCC regulator apply valve bore  24   e.    
     A method according to the present invention for repairing an automatic transmission is described in  FIG. 6 . The method includes the steps of removing an automatic transmission oil sump pan from the automatic transmission at step  100 , removing a valve body exposed by removing the oil sump pan from the automatic transmission and separating the valve body from a separator plate at step  102 , positioning a Torque Converter Clutch (TCC) regulator valve in an open position to align a spool area of the TCC regulator apply valve with an open chamber of the valve body at step  104 , inserting a TCC regulator apply valve clip into the open chamber of the valve body to engage the spool area of the TCC regulator apply valve with a convex dished side of the TCC regulator apply valve clip in the opening direction of the TCC regulator apply valve at step  106 , reinstalling the valve body and separator plate at step  108 , and reinstalling the automatic transmission oil sump pan at step  110 . 
     While the invention herein disclosed has been described by means of specific embodiments and applications thereof, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope of the invention set forth in the claims.