Abstract:
A valve body for use in an automatic overdrive transmission where the hydraulic fluid passages are blocked in selected locations in the body. The blockages result in increased pressure in the free passages and redirection of fluid flow such that the reverse clutch assembly is operable in third gear. By this procedure, the torque capacity of the transmission is increased.

Description:
COPYRIGHT NOTICE 
     A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the fascimile reproduction of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a modified valve body and more particularly, the present invention relates to a valve body and automatic transmission incorporating the valve body as well as a method of operating the valve body for enhanced torque capacity from an automatic transmission. 
     BACKGROUND OF THE INVENTION 
     In a conventional automatic overdrive transmission, two distinct input shafts are provided consisting of an outer and an inner input shaft. Accordingly, power train energy can be manipulated to enhance torque output. Typically, in the conventional transmission the outer input shaft is driven by the turbine of the torque converter, while the inner input shaft receives drive energy from the front cover of the torque converter. The cover rotates continuously during the operation of the engine. 
     The outer input shaft is responsible for operation of first gear, second gear, reverse gear and partly for third gear (60%). In contrast, the inner input shaft partly operates third gear and fourth gear entirely. 
     A system whereby such a transmission could be employed for enhanced torque capacity given the input shaft relationship has not been previously recognized in the art. 
     SUMMARY OF THE INVENTION 
     One object of the present invention is to provide an improved transmission and method of operation for increasing the torque capacity of a standard automatic overdrive transmission. 
     A further object of the present invention is to provide a method of increasing torque capacity in an automatic overdrive transmission, the transmission having a third gear and fourth gear clutch assembly, a reverse/forward clutch assembly and a torque converter with a turbine, the method comprising: 
     providing a valve body having a plurality of hydraulic valves for controlling up shift and downshift of transmission gears, the body having a network of fluid passages therein; 
     providing an automatic overdrive transmission having an inner input shaft and an outer input shaft coaxially arranged with the outer input shaft, the inner input shaft for partially operation of third gear and entire operation of fourth gear; 
     coupling the inner input shaft and the outer input shaft to the turbine of the torque converter; and 
     selectively blocking the fluid passages for redirecting hydraulic fluid flow in the passages of the valve body to operate the reverse clutch assembly in third gear whereby torque capacity of the transmission is increased. 
     A further object of one embodiment of the present invention is to provide a method of increasing torque in an automatic overdrive transmission, the transmission having a third gear and fourth gear clutch assembly, a reverse/forward clutch assembly and a torque converter with a turbine, the method comprising: 
     providing a valve body having a plurality of hydraulic valves for controlling up shift and downshift of transmission gears, the body having a network of fluid passages therein; 
     providing an automatic overdrive transmission having an inner input shaft and an outer input shaft coaxially arranged with the inner input shaft, the inner input shaft for partially operation of third gear and entire operation of fourth gear; 
     removing the inner input shaft and the outer input shaft; 
     coupling the single shaft to the turbine of the torque converter; and 
     selectively blocking the fluid passages for redirecting hydraulic fluid flow in the passages of the valve body to operate the reverse clutch assembly in third gear whereby torque output of the transmission is increased. 
     A still further object of one embodiment of the present invention is to provide an automatic overdrive transmission having increased torque output, comprising; 
     an automatic overdrive transmission including a third gear and fourth gear clutch assembly, a reverse/forward clutch assembly, a torque converter with a turbine an inner input shaft and an outer input shaft, the inner input shaft for partially operation of third gear and entire operation of fourth gear; 
     the inner input shaft and the outer input shaft coupled to the turbine of the torque converter; and 
     a valve body having a plurality of hydraulic valves for controlling up shift and downshift of transmission gears, the body having a network of fluid passages therein, at least some of the passages being blocked for redirecting hydraulic fluid flow in the passages of the valve body to operate the reverse clutch assembly in third gear whereby torque capacity of the transmission is increased. 
     Having thus described the invention, reference will now be made to the accompanying drawings illustrating preferred embodiments. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-section of a typical automatic overdrive transmission; 
     FIG. 2 is a plan view of one embodiment of the valve body of the present invention; 
     FIG. 3 is an exploded view of the conventional valve body employed in the transmission of FIG. 1; 
     FIG. 4 is a top plan view of the hydraulic fluid circuit passages of the modified valve body according to one embodiment of the present invention; and 
     FIG. 5 a  is a perspective view of the standard input/out shaft associated with the automatic overdrive transmission; and 
     FIG. 5 b  is a perspective view of a one-piece shaft suitable for use in the present invention. 
     Similar numerals employed in the text denote similar elements 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings, FIG. 1 illustrates a cross-section of a conventional automatic overdrive transmission. In general overview, numeral  10  represents the torque converter which couples the vehicle engine (not shown) to a planetary gear train  12 . A damper assembly  14  is adjacent the torque converter  10 . A direct drive shaft  16  (¾ input) couples the engine (not shown) to the direct clutch  18 . An oil pump assembly  22  supplies oil to operate clutches, bands, torque converter, etc. , and dissipate heat from the transmission. An outer input shaft  20  connects the turbine to forward drive and reverse clutch as is known in the art. 
     Turning to the various clutch assemblies, the intermediate clutch is denoted by numeral  24 , intermediate one way clutch is represented by numeral  26  and the front overdrive band is referenced by numeral  28 . The reverse clutch, forward clutch and planetary one way clutch are denoted by numerals  30 , 32  and  34 , respectively. The remaining components include a low reverse band  36 , direct clutch  18 , compound planetary gear set  12 , governor  38  and the control valve body  40 . 
     FIG. 2 illustrates the conventional hydraulic fluid circuit in schematic form. As is known, the circuit includes a sump  42  for supplying hydraulic fluid to the system, a protective screen  44 , pump  46  and oil pressure booster valve  48  for adjusting pressure relative to throttle (not shown) opening. Main regulator valve  50  controls pressure in the system and converter relief valve  52  precludes excessive pressure from building in the torque converter  10  (FIG.  1 ). Additional elements in the system include converter  54 , valve  56  and cooler  58  all of which function in a known manner. 
     Numeral  60  denotes the 3-4 accumulator which smooths 3-4 up shifting. The 1-2 capacity modulator valve  62  and 1-2 accumulator valve  64  cooperate to cushion 1-2 up shifting in the transmission. An overdrive servo regulator valve  66  applies pressure for 4-3 downshifting and 3-4 shuttle valve  68  controls valve  66 . 
     The 1-2 shift valve  70  controls up and down shifting, while T.V. limit valve  72  controls the pressure experienced by valve  48 . Numeral  74  denotes a check valve with the remaining common valves referenced commonly. 
     The 3-4 shift valve  76  operates automatic 3-4 up and 4-3 down shifting. A modulator valve  78  controls the pressure on valve  76 . Orifice valve  80  precludes shifting from second gear into overdrive. Modulator valve  82  controls pressure on 2-3 accumulator valve  84 . The 2-3 back out valve  86  controls the direct clutch  18  (FIG.  1 ). Throttle plunger  88  changes the spring force on throttle valve  90 . Manual valve  92  moves with the shift selector  94  to provide automatic functions of the hydraulic system. 
     The 2-3 shift valve  96  controls up 2-3 and down 3-2 shifting and modulator valve  98  controls the pressure on valve  94 . A 3-4 back out valve  100  buffers 3-4 up shifting if such shifting occurs in a closed throttle condition and 2-1 scheduling valve  102  regulates 2-1 down shifting speed upon selector  94  being moved from manual low from direct drive or overdrive. Modulator valve  106  and relief valve  108  complete the circuit. 
     FIG. 3 illustrates the conventional valve body  40  housing the hydraulic circuit in a top plan and exploded form. The body  40  comprises a network of fluid passages  42  and valve members, the latter having been discussed supra. As is evident, the valves all include typical springs, clips etc. which will not be discussed further. In contrast to the conventional body  40  in FIG. 3, FIG. 4 illustrates the modified valve body according to one embodiment of the present invention. 
     Reference to the numerals and circuits depicted in FIGS. 3 and 4 will be of use in the following description. In the embodiment, apertures are made in body  40  into the bore for manual valve  92  and blockage of passage  120  results in a delay of pressurization of valve  96  until the manual valve  92  is moved into the overdrive position (not shown) as selected with selector  94 . A second blockage is made at location  122  in the body  40  to block redirected mainline pressure from escaping through the 2-3 shift valve  96 . A blockage at location  124  eliminates the reverse boost. 
     Locations  126  and  128  are joined by a hollow tube (not shown) on the underside of the body  40  for redirection of reverse clutch fluid pressure from  126  to  128 . A bridge  130  is employed to connect forward clutch fluid pressure to the low reverse servo modulator valve  104 . A blockage at location  130  precludes forward clutch pressure from entering the valve  104 . A blockage at location  134  prevents fluid from entering the 2-1 scheduling valve  102  and plug or blockage at location  136  prevents pressure escape into valve  102 ; aperture  138  exhausts cross leaked pressure. 
     Location  140  may be blocked to prevent redirected clutch pressure from entering valve  106 . An aperture (not shown) is formed at location  142  to allow fluid to by pass the park/1 st /reverse circuit the 1-2 shift valve  70 . A further aperture (not shown) at location  144  exhausts residual pressure from valve  106 . Finally, an aperture (not shown) at location  146  by passes direct clutch pressure through blocked location  122  into the former 2-3 cut back circuit. 
     FIG. 5 a  illustrates the drive shaft typically provided in the automatic overdrive transmission. The shaft comprises an outer  150  and inner  152  which, when assembled, are in a coaxial relationship. FIG. 5 b  illustrates a single shaft  154  manufactured by G.E.R. of Pennsylvania. 
     As stated herein previously, when the stock or standard shaft arrangement  150 ,  152  is employed, the same may be coupled to the turbine of the torque converter; shaft  154  may alternatively be used by replacing shafts  150 ,  152 . 
     It has been found that by making use of the present invention, a 58.5% increase in clutch area becomes available for third gear, thus significantly enhancing the torque capacity of the transmission. 
     Although embodiments of the invention have been described above, it is not limited thereto and it will be apparent to those skilled in the art that numerous modifications form part of the present invention insofar as they do not depart from the spirit, nature and scope of the claimed and described invention.