Abstract:
A replacement torque converter clutch regulator valve assembly for use within an automatic transmission including two cooperating valves, namely a regulator apply valve and an isolator valve, disposed in fluid communication with a line pressure circuit and a torque converter clutch apply circuit is disclosed. In one embodiment the regulator apply valve employs a regulator apply valve sleeve, which provides support to the regulator apply valve to prevent side loading. Modified control lands on the regulator apply valve have a reduced cross-sectional area calculated to increase the influence of the pulse width modulated solenoid, which provides an output pressure in response to the duty cycle imposed on the solenoid coil in pulse width modulated converter systems. In an alternative embodiment an isolator valve sleeve is utilized for instances wherein the isolator valve bore has extreme wear that cannot be corrected solely by the installation of the replacement isolator valve.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional application of U.S. patent application Ser. No. 10/424,894 filed Apr. 28, 2003 now U.S. Pat. No. 6,990,996, entitled Torque Converter Clutch Regulator Valve Assembly and Method of Installation. 
    
    
     BACKGROUND OF INVENTION 
     The present invention relates to the field of hydraulic circuits within automatic transmission systems and, more particularly, to a replacement torque converter clutch (hereinafter “TCC”) regulator valve that reduces fluid pressure loss to the torque converter apply and release circuits, which actuate the torque converter clutch. 
     The General Motors 4L60-E (hereinafter “GM”) transmission and other similar GM transmissions are equipped with mechanisms to “lockup” their torque converters to varying degrees under certain operating conditions. The purpose of the lockup converter is to provide for direct drive when the vehicle is cruising at higher speeds. Since there is always some slippage in the fluid coupling of a torque converter, some power is lost and fuel economy suffers. By providing a direct mechanical coupling through the transmission at high engine speeds, the lockup converter improves fuel economy. 
     This is accomplished by an electronic/hydraulic torque converter clutch system, which utilizes a lockup piston within the torque converter housing. The lockup piston has friction material on its forward surface. When the vehicle is at cruising speed and lockup is desired, an electric solenoid is energized which opens the torque converter clutch (hereinafter “TCC”) regulator valve. This allows fluid pressure to act upon the lockup piston, which is forced against a machined surface on the converter cover. Thus, the lockup piston and the converter cover are locked together and act as a single unit similar to a manual transmission clutch. When lockup is no longer required, a port opens that allows the pressurized fluid to exhaust. The lockup piston then moves away from the torque converter housing re-establishing the fluid coupling. 
     Early 4L60E transmissions utilized 2 nd  gear clutch fluid, which was essentially line pressure applied via an orifice, to actuate the TCC regulator valve. In this version of the transmission, the TCC regulator valve and the isolator valve were combined into one valve. In later versions lockup in the electronic torque converter clutch system was controlled by a pulse width modulated torque converter clutch (hereinafter “PWM TCC”) solenoid that provides an output or control pressure in response to the duty cycle imposed on the solenoid coil. 
     In 1993 General Motors converted to the PWM actuated TCC regulator valve and divided it into two separate valves, namely the regulator apply valve and the isolator valve. Thus, in the PWM versions (1993–1997) of the 4L60E torque converter, there are actually two converter solenoids being employed in the system. The PWM TCC solenoid sends automatic transmission fluid (hereinafter “ATF”) to the isolator valve. Since the PWM TCC solenoid is duty-cycling the isolator valve, it oscillates continuously within the valve body. The regulator apply valve receives line pressure and regulates it to a lesser pressure, which is known as converter apply pressure. Converter apply pressure is not actually sent to the torque converter, but to the TCC apply valve. The TCC apply valve is actuated by the TCC solenoid. This solenoid is simply an On/Off type solenoid and not a PWM type. It is the TCC apply valve that actually directs ATF to the torque converter. 
     In 1998 General Motors went to the “EC3” style torque converter. This design allows the torque converter to continuously slip from 2 nd  gear upward without ever locking up completely. This design was intended to improve fuel economy and converter control. The regulator apply and isolator valves were changed only slightly and function exactly the same as the 1993–1997 PWM version. 
     A disadvantage associated with these systems is the pulsating flow generated by the pulse width modulated TCC isolator valve as it cycles between its open and closed positions. The isolator valve imparts some of this pulsating movement to the regulator apply valve. These pulsations cause wear within the valve body resulting in hydraulic fluid leakage and incorrect pressure responses. As a result vehicles with a 4L60E transmission often have insufficient TCC apply pressure causing uncontrolled clutch slippage, which overheats the converter and generates TCC slip codes requiring service work. These complaints can often be caused by ATF leakage past the TCC regulator valve resulting in reduced converter apply pressure. 
     There are known prior art patents that are available in the field and their discussion follows. One example is U.S. Pat. No. 4,271,939 to Iwanga et al. (hereinafter “939 patent”), which discloses a hydraulic control system for a torque converter for ensuring release of the lock-up condition of the torque converter. This is accomplished by providing a flow restrictor in the hydraulic working fluid supply passage for the torque converter to make the flow resistance of the passage equal to or larger than the flow resistance of the hydraulic working fluid supply passage for the lock-up control chamber. In this control system a first or feed passageway communicates with a source of pressurized fluid and with a torque converter chamber, a second or discharge passageway communicates with the torque converter chamber and a third passageway communicates with a lock-up control or clutch chamber of the lockup clutch. A lockup control valve communicates with the same source of pressurized fluid and with the third passageway. The first passageway is provided with the flow restrictor. With the provision of the flow restrictor, the disengagement of the lockup clutch will be assured upon pressurization of the third passageway. 
     Another example is U.S. Pat. No. 4,618,036 to Ideta (hereinafter “036 patent”), which discloses a hydraulic control system for the lockup clutch of a torque converter wherein release of a lockup clutch is ensured even when the discharge flow rate of the pump is low. This control system comprises a pump driven by an engine to discharge fluid, a torque converter having a lockup clutch with a lockup clutch piston movable to a clutch released position when fluid pressure within a lockup release chamber is higher than fluid pressure within a working chamber in the torque converter cavity, a line pressure regulator valve and an orifice, which provides a restricted flow communication between the torque converter and the pump even when line pressure generated by the line pressure regulator valve is lower than a predetermined value. The Ideta (&#39;036) patent utilizes cutouts 20 formed on the land 32 d  of the first spool 32 (FIG. 1) on the line pressure regulator valve to permit a sufficient flow of hydraulic fluid via oil conduit 62 to torque converter 10 at low speed operation to ensure the release of the lockup clutch. 
     While these patents relate generally to hydraulic control systems for torque converters, they do not disclose improving hydraulic control over the torque converter clutch apply circuit or a related method for restoring the hydraulic integrity of such circuits by use of a replacement valve mechanism. 
     Pending U.S. patent application Ser. No. 09/939,372 to Stafford discloses an actuator feed limit valve (hereinafter “AFL”) assembly comprising a replacement hydraulic valve mechanism for installation within the original equipment valve body of an automatic transmission. The AFL valve directs line pressure into the actuator feed limit circuit, which feeds the shift solenoids, pressure control solenoid and other hydraulically actuated components of the transmission. This valve mechanism utilizes a full contact valve sleeve having inlet and exhaust ports disposed about its circumference, which substantially reduces side loading, bore wear, and AFL fluid circuit leakage. However, this patent application does not disclose the structural improvements and technical advantages of the present invention. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is a replacement TCC regulator valve assembly for the GM 4L60-E transmissions comprised of two separate valves, namely a regulator apply valve and an isolator valve, which is designed to increase fluid pressure within the torque converter apply circuit and to restore the hydraulic integrity thereof. 
     In one embodiment the replacement TCC regulator valve assembly employs a wear-resistant regulator apply valve sleeve, which has been added to provide full support to the regulator apply valve to prevent side loading (i.e. lateral movement) in operation. The control lands or so-called spools on the regulator apply valve have been reduced in diameter area by up to 10% in comparison to the original equipment valve, which reduces the balance circuit apply surface on the end face of the apply valve. Thus, the overall effect is to increase the influence of the PWM TCC solenoid on valve operation resulting in increased line pressure flow to the converter apply circuit for transmissions having such PWM converter systems. 
     In addition, the axial length of the replacement isolator valve has been increased in comparison to the original equipment valve to reside in contact with the unworn portions of the mating bore in the valve body to ensure accurate operation. Annular lubrication grooves have also been added to the present isolator valve for better valve centering to improve performance. 
     In an alternative embodiment, an optional isolator valve sleeve is added to the present TCC regulator valve assembly for instances wherein the OEM isolator valve bore has extreme wear that cannot be corrected solely by the installation of a replacement isolator valve. 
     There has thus been outlined, rather broadly, the important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are additional features of the invention that will be described hereinafter and which will form the subject matter of the claims appended hereto. 
     Other features and technical advantages of the present invention will become apparent from a study of the following description and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The novel features of the present invention are set forth in the appended claims. The invention itself, however, as well as other features and advantages thereof will be best understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying figures, wherein: 
         FIG. 1A  is a longitudinal cross-section of a TCC regulator valve assembly disposed within the valve body of a GM transmission and labeled Prior Art; 
         FIG. 1B  is a longitudinal cross-section of another embodiment of a prior art TCC regulator valve assembly disposed within the valve body of a GM transmission labeled Prior Art; 
         FIG. 2A  is a longitudinal cross-section of a reaming tool within the valve body for resizing the bore prior to installation of a remanufactured TCC regulator valve assembly labeled Prior Art and shown in  FIG. 2B ; 
         FIG. 2B  is a longitudinal cross-section of a remanufactured TCC regulator valve labeled Prior Art; 
         FIG. 3A  is a longitudinal cross-section of the replacement TCC regulator valve assembly of the present invention shown in the closed position; 
         FIG. 3B  is a longitudinal cross-section of the replacement TCC regulator valve of  FIG. 3A  shown in the open position; 
         FIG. 4  is a side elevational view of the modified regulator apply valve of the present invention; 
         FIG. 5  is a longitudinal cross-section of the regulator apply valve sleeve of the present invention; 
         FIG. 6  is a longitudinal cross-section of the modified isolator valve of the present invention; 
         FIG. 7  is a longitudinal cross-section of a reaming tool of the present invention within the valve body for resizing a first axial section of the bore prior to installation of the present TCC regulator valve assembly shown in  FIGS. 3A and 3B ; 
         FIG. 8  is a longitudinal cross-section of another embodiment of the replacement TCC regulator valve assembly including an isolator valve sleeve; and 
         FIG. 9  is a longitudinal cross-section of an alternative reaming tool of the present invention for resizing a second axial section of the bore prior to the installation of the replacement TCC regulator valve assembly including the isolator valve sleeve shown in  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Prior to describing the present invention in detail it may be beneficial to review the structure and function of a TCC regulator valve of the prior art. With reference to the drawings there is shown therein such a TCC regulator valve of the prior art, indicated generally at  100  and illustrated in  FIG. 1A . The prior art TCC regulator valve  100  made available in some GM vehicles from 1993 to 1997 is comprised of a regulator apply valve  102 , an isolator valve  105 , and an isolator valve spring  106  arranged within the valve body  110 . 
       FIG. 1B  illustrates another prior art TCC regulator valve, indicated generally at  200 , which was made available on GM vehicles in 1998. The TCC regulator valve  200  is similarly constructed for installation in the valve body  110  with the exception of the isolator valve  105 ′ wherein the configuration has been modified. 
     Still referring to  FIG. 1B  these components are arranged in coaxial relation as shown within a mating bore  111  and are captured in the valve body  110  by an end plug  115 , which is secured by a retaining clip  117 . The valve body  110  includes ATF exhaust ports  107 ,  108 , a PWM TCC solenoid circuit as at  112  for receiving pressurized ATF, a line pressure port  113  for counteracting fluid pressure delivered via the PWM TCC solenoid port  112 , a TCC apply circuit as at  114  for sending pressurized ATF to the TCC apply valve (not shown), and a TCC apply balance port  116 . 
     In the early prior art designs the isolator valves  105 ,  105 ′ ( FIGS. 1A and 1B ) are fabricated from steel. Valves  105 ,  105 ′ continuously oscillate within the bore  111  of the aluminum valve body  110  as the PWM TCC solenoid cycles to provide smooth converter clutch engagement. Such oscillating movement wears the bore  111  at locations adjacent the isolator valves  105 ,  105 ′ allowing PWM TCC solenoid pressure to leak past the isolator valves  105 ,  105 ′ to exhaust. The regulator apply valve  102  also wears the bore  111  allowing converter apply pressure leakage, which eventually causes unwanted clutch slippage and overheating of the torque converter. 
     It is known in the prior art to ream the bore  111  oversize by the use of a suitable reaming tool  150  as shown in  FIG. 2A  to resurface the bore and to replace the original equipment manufacture (hereinafter “OEM”) valves  102 ,  105  with oversize valves  102 ′,  105 ′ as seen in  FIG. 2B . However, using this repair technique and the resulting remanufactured TCC regulator valve assembly  300  ( FIG. 2B ) has proven to be unsatisfactory and has resulted in very early wear problems in such remanufactured units. Thus, the present invention has been developed to resolve these problems and will now be described. 
     Referring to  FIGS. 3A and 3B  there is shown a replacement TCC regulator valve assembly in accordance with the present invention, indicated generally at  10 . The present TCC regulator valve assembly  10  includes a replacement regulator apply valve, indicated generally at  20 , a new regulator apply valve sleeve, indicated generally at  15 , and a replacement isolator valve, indicated generally at  25 . The OEM isolator valve spring  106  and the OEM retaining clip  117  may be reused in the present invention. The OEM end plug  115  is effectively integrated into the present sleeve  15  and, thus, the OEM plug  115  may be discarded. 
     Referring to  FIG. 4  the present regulator apply valve  20  is illustrated. This spool-type valve  20  includes a pair of control diameters or lands  42 ,  45  interconnected by a stem portion  43 , which may include a peripheral groove formed thereon (not shown) for identification purposes. A spring locating diameter  40  is formed coaxially with land  42  and functions to guide the spring  106  against the end face of land  42 . 
     Land  42  also includes an annular, lubrication groove  24  that fills with ATF during operation. This provides an even film of lubrication about land  42 , which resists side loading and uneven wear within the mating bore  111 . The end face  45   a  of land  45  in combination with the end face  46   a  of the chamfered contact diameter  46  defines a reaction surface (i.e. balance apply surface) for pressurized ATF entering the balance apply port at  116  ( FIGS. 3A and 3B ). 
     Lands  42 ,  45  function to control the flow of line pressure as at  113  to the TCC apply circuit  114  as hereinafter described. In the present invention the outside diameters of lands  42 ,  45  have been reduced by up to 10% in comparison to the OEM apply valve  102  to reduce the balance apply surface  45   a ,  46   a  (as defined hereinabove) rendering the present regulator apply valve  20  less responsive to balance apply pressure via circuit  116  and, accordingly, more responsive to pulse width modulated (PWM) solenoid control via circuit  112 . This results in an increased flow of ATF from line pressure circuit  113  to converter apply circuit  114  and higher converter apply pressure in operation. 
     In the preferred embodiment the regulator apply valve  20  is fabricated from aluminum material per 6262-T8/T9 or 6061-T6 and is hard anodized per MIL-A-8625, Type III, Class 2 to provide an optimal coefficient of friction with the mating valve sleeve  15 . 
     As more clearly shown in  FIG. 5 , sleeve  15  is a generally cylindrical construction having a longitudinal bore  14  of sufficient size to allow valve  20  to oscillate therein. Sleeve  15  includes a plurality of inlet ports  16  and a plurality of outlet ports  18  formed within annular grooves  45  at predetermined locations in fluid communication with the line pressure port  113  and the TCC apply circuit  114  respectively ( FIG. 3B ). Sleeve  15  includes at least one TCC balance apply orifice  19  formed within the annular groove  40  ( FIG. 5 ) at a predetermined location in fluid communication with the TCC balance apply circuit  116 . The sleeve  15  may also include a plurality of exhaust ports  17  formed at a distal end thereof in proximity to exhaust port  108 . 
     An annular groove  21  is formed at one end of the sleeve  15  for receiving the OEM retaining clip  117 . Once the valve sleeve  15  is placed within the valve body  110 , the retaining clip  117  is installed within the annular groove  21  to secure the sleeve  15  and the entire TCC regulator valve assembly  10  within the valve body  110 . Thus, it will be appreciated that the primary feature (i.e. groove  21 ) and the function (i.e. valve containment) of the prior art end plug  115  ( FIG. 1A ) are effectively integrated into the present regulator apply valve sleeve  15 . 
     In one embodiment the sleeve  15  is fabricated from a high grade 4032-T6/T651/T86 aluminum to provide an optimal working surface for contact with the hard anodized regulator apply valve  20  and increased service longevity in comparison to the OEM design. The present sleeve  15  functions to restore the hydraulic integrity of the TCC apply circuit  114  and to provide full support to the regulator apply valve  20  within the sleeve  15  thereby eliminating the side-loading problem inherent in the OEM design. 
     Referring to  FIG. 6  there is shown a replacement isolator valve in accordance with the present invention, indicated generally at  25 . Isolator valve  25  is a generally cylindrical construction fabricated from low carbon steel and case hardened to a predetermined case depth to resist wear. Isolator valve  25  includes a plurality of annular grooves  50  formed thereon, which function to center the valve  25  within the bore  111  by filling with ATF during operation and to distribute hydraulic pressure across the surface of the valve to prevent side-loading. In the embodiment shown four annular grooves  50  are formed in parallel relation at regular intervals on the outside diameter of the valve  25 . 
     The replacement isolator valve  25  has an increased axial length that is approximately 0.560 inches longer than the OEM isolator valves  105 ,  105 ′,  105 ″ ( FIGS. 1A ,  1 B, and  2 B), and yet retains adequate clearance and proper function within its mating bore  111  in the OEM valve body  110 . The increased axial length allows the isolator valve  25  to ride in the unworn portions of the valve body  111  in the area adjacent exhaust port  107  ( FIG. 3B ) ensuring concentric operation of the isolator valve  25  in combination with the regulator apply valve  20 . 
     The isolator valve  25  includes a spring recess  27  integrally formed therein at a proximal end thereof to receive spring  106 . The isolator valve  25  may also include an axial protuberance  29  formed on a distal end thereof. The protuberance  29  permits ATF entering the PWM TCC solenoid port  112  to flow evenly around protuberance  29  to the actuating surface  25   a  of the valve  25 . The protuberance  29  also prevents the end face of the valve  25  from striking against the inside of the valve body  110  as at  130  ( FIG. 3A ), which would disrupt ATF flow resulting in pressure loss within the converter apply circuit  114 . 
     To install the present TCC regulator valve assembly  10 , the retaining clip  117 , end plug  115 , regulator apply valve  102 , spring  106 , and either isolator valve  105  or  105 ′ of the prior art are removed from the valve body bore  111 . The OEM clip  117  and spring  106  are retained for reuse. Using a reaming tool  150 ′ such as Sonnax reamer (77754-R2) the bore  111  is enlarged to a sufficient size to accommodate the valve sleeve  15  as illustrated in  FIG. 7 . Reamer  150 ′ includes a cutting diameter  152 , which is piloted by a guide diameter  154  that locates in a distal end (i.e. second axial section) of the bore  111  to ensure that the sleeve  15  will be concentric to the isolator valve  25  once installation is complete. After removal of any debris and burrs from the resized proximal end (i.e. first axial section) of bore  111  and applying lubrication, the present TCC regulator valve assembly  10  is installed as shown in  FIGS. 3A and 3B . 
     In some instances the distal end of the bore  111  wherein the isolator valve  25  resides has such extreme wear that even the present modified isolator valve  25  will not prevent excessive oil loss. In this circumstance another embodiment of the TCC regulator valve assembly  10 ′ is provided as shown in  FIG. 8 . In this embodiment an isolator valve sleeve, indicated generally at  60 , is utilized to remedy the leakage problem and to restore hydraulic integrity to the present valve assembly  10 ′. 
     The isolator valve sleeve  60  is a generally cylindrical construction, which is also fabricated from a high grade 4032-T6/T651/T86 aluminum and includes an internal bore  62  of a sufficient size to permit the oscillating movement of the present Isolator Valve  25  as described hereinabove. Sleeve  60  is provided with a plurality of inlet ports  16 ′ and a plurality of outlet ports  18 ′ formed at 90 degree intervals within annular grooves  49 ′ at predetermined locations in fluid communication with the PWM TCC solenoid circuit  112  and exhaust port  107  respectively in a manner similar to the regulator valve sleeve  15  ( FIG. 5 ). 
     The present sleeve  60  functions to restore the hydraulic integrity of the TCC solenoid circuit  112  and to provide full support to the isolator valve  25  within the sleeve  60  thereby eliminating side-loading and the excessive wear problems inherent in the OEM and remanufactured OEM designs described hereinabove. In all other respects the TCC regulator valve assembly  10 ′ including the isolator valve sleeve  60  operates in substantially the same manner as the TCC regulator valve  10  as described hereinabove. 
     In order to install the TCC regulator valve assembly  10 ′ an alternate reaming tool  150 ″ such as Sonnax reamer (77754-RM5) is utilized to enlarge the distal end (i.e. second axial section)  111   b  of the bore  111  to a sufficient size to accommodate the valve sleeve  60  as illustrated in  FIG. 9 . After removal of any debris and burrs from the resized distal end  111   b  of the bore  111  and applying lubrication, the present regulator valve assembly  10 ′ is installed as shown in  FIG. 8 . 
     In operation the output pressure from the PWM TCC solenoid in the high duty cycle enters the TCC regulator valves  10 ,  10 ′ via the PWM TCC solenoid circuit  112 , which strokes the isolator valve  25  (i.e. to the right) from the closed position shown in  FIG. 3A  to the open position shown in  FIG. 3B . It can be seen that the proximal end of the isolator valve  25  surrounding spring recess  27  resides in an unworn portion of the bore  111   b  ( FIG. 3B ) adjacent the exhaust port  107 , which would not have been traversed by any of the OEM isolator valves  105 ,  105 ′,  105 ″ due to their shorter axial length. 
     Simultaneously, the regulator apply valve  20  is also stroked opening the TCC apply circuit  114  to line pressure via line port  113  ( FIG. 3B ). As the apply valve  20  oscillates within the sleeve  15 , the groove  24  functions to distribute pressure across the circumference of land  42  eliminating side loading of the valve  20  within sleeve  15 . It can be seen that sleeve  15  extends partially over exhaust port  108  ( FIG. 3B ). This protects that portion of the bore  111   a  that is susceptible to wear in the OEM design due to repeated oscillation and causes ATF/pressure leakage in the prior art regulator apply valves  102 ,  102 ′. 
     As the PWM TCC solenoid cycles and returns to a lower percentage duty cycle, the hydraulic pressure in the PWM TCC solenoid circuit  112  is depleted. The isolator spring  106  then forces the Isolator Valve  25  back to the closed position with the assistance of fluid pressure entering the balance apply circuit at  116  and the solenoid cycle is repeated. 
     Although not specifically illustrated in the drawings, it should be understood that additional equipment and structural components will be provided as necessary and that all of the components described above are arranged and supported in an appropriate fashion to form a complete and operative torque converter clutch regulator valve assembly and method of installation incorporating features of the present invention. 
     Moreover, although illustrative embodiments of the invention have been described, a latitude of modification, change, and substitution is intended in the foregoing disclosure, and in certain instances some features of the invention will be employed without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of invention.