Abstract:
A drive combination that is disclosed that is particularly suited for use in automobiles constructed to engage in acceleration racing. The drive combination includes a torque converter drive unit that is driven by an engine, and a countershaft transmission that that is driven by the torque converter drive unit. The disclosed drive combination requires less power to drive than known torque converter drive and planetary gear transmission drive combinations used for automobile racing and is lighter than such known drive combinations.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the priority of provisional application Serial No. 60/127,691, filed Apr. 5, 1999. That application is hereby incorporated herein by reference. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     Power is conventionally transmitted from the engine of an automobile or a truck through one of two conventional combinations of power transmission devices. One combination is a mechanically operated friction clutch and a manually shifted countershaft transmission. The other combination is a hydrodynamic drive, typically a torque converter, and an automatically shifted planetary gear transmission. 
     The clutch and manually shifted countershaft transmission combination includes a friction clutch that is mounted to a flywheel on the vehicle&#39;s engine. An input shaft of the countershaft transmission engages and is driven by a driven component of the clutch, conventionally a disk that frictionally engages the flywheel. Countershaft transmissions have meshing gears mounted on parallel shafts. The speed ratio and torque ratio provided by the transmission depends on the ratios of the meshing pairs of gears through which power is transmitted from the input shaft of the transmission to the output shaft. A countershaft transmission is conventionally either a sliding gear transmission or a constant mesh transmission. In a sliding gear transmission, gears are moved along a shaft into or out of engagement with another gear to change the path through which power is transmitted through the transmission and thereby changes the transmission ratios. In a constant mesh transmission, gears are constantly in mesh and positive engagement or friction devices couple the gears to a shaft of the transmission. In either type of transmission, ratios are changed by operation of a shifter mechanism that moves gears in the case of a sliding gear transmission or operates friction or positive engagement devices in the case of a constant mesh transmission. 
     The hydrodynamic drive and automatically shifted planetary gear transmission combination is driven by a torque converter mounted to a flywheel on an engine. An input shaft of a planetary gear transmission engages and is driven by the torque converter. The planetary gear transmission conventionally has planetary gear assemblies aligned along the axis of the input shaft. Power is transmitted through the planetary gear assemblies by fixing one of the three components of the assembly, the sun gear, the plane gear carrier, or the ring gear, against rotation and applying power to one of the other two components to drive the remaining component. The drive ratio of the transmission is determined by the diameters of the gears of the planetary gear assemblies through which power is transmitted. The path through which power is transmitted through planetary gear assemblies is changed by hydraulically operated devices. A hydraulically operated brake having a band that is mounted to the transmission case and surrounds the ring gear of a planetary gear assembly is conventionally used to secure the ring gear to the transmission case. When the ring gear is secured to the transmission case, power may be transmitted through the sun and planet gear carrier of the planetary gear assembly. Hydraulically operated clutch pack assemblies having adjacent disks that alternately engage a surrounding case and an inner splined shaft are used to selectively couple and uncouple the shaft to the case by applying or removing a hydraulic pressure to the assembly. Hydraulically operated frictional engagement devices, brake bands and clutch packs, provide control of the performance of the transmission. Frictional engagement devices that engage and disengage to change the ratio of planetary gear transmissions can provide a high level of mechanical reliability. Because those devices are actuated by hydraulic pressure, planetary gear transmissions are conventionally shifted automatically by controlled application of hydraulic pressure to frictional engagement devices in the transmission. 
     These conventional power transmitting combinations have been the bases from which power transmitting combinations and devices have been specifically designed and constructed for use in racing. Racing that primarily requires acceleration, in particular, requires transmissions that are more durable and that must satisfy different requirements than do conventional automotive transmissions. In acceleration racing, such as drag racing, either the maximum available power or the maximum power that can be used to accelerate the car is transmitted through the driveline of the racecar throughout the race. The transmission must provide a high degree of mechanical reliability both in changing gear ratios and in structural reliability. Failure to quickly change gears and failure of a component of the transmission are both causes of lost races. 
     Cars having the most powerful engines used in drag racing have long required transmissions specifically constructed to transmit the large power created by their engines. Specially constructed planetary gear transmissions that have large and high strength gears and other components have been used in various forms of racing, including drag racing for many years. These transmissions, manufactured by Lenco, Inc. and others, have used high strength planetary gear assemblies with mechanically operated friction engagement devices to provide both reliable changes of transmission ratios and structural reliability. 
     The most powerful cars for which planetary gear transmissions were specially constructed have conventionally driven these transmissions by clutches that are constructed to provide a significant amount of control of the rate at which the high power generated by the engines of these cars is applied to the driveline of the racecar. The planetary gear transmissions specially constructed for racing and used in the most powerful racecars are coupled to the engine differently than planetary gear transmissions used in conventional automotive applications in that they have been driven by clutches and have conventionally been shifted by mechanically or pneumatically, rather than hydraulically, actuated mechanisms. 
     While racing planetary gear transmissions provide mechanically reliable gear ratio changes and structural reliability, that reliability comes at the price of requiring power to drive the large and heavy components of the transmission. A significant amount of power is required to drive heavy components of racing planetary gear transmissions. The power required to drive racing planetary gear transmissions is not a significant disadvantage to racecars having the highest power engines. However, the power required to drive these transmissions is a significant disadvantage to racecars that are limited to engines that do not produce more power than the racecar can utilize to increase performance. For such cars, decreasing the power consumed by driving components of the car increases the power that can be used to drive the car and to thereby increase performance. 
     Countershaft racing transmissions that require less power to drive than racing planetary gear transmissions have recently been developed. In addition to requiring less power to drive than planetary gear racing transmissions, racing countershaft transmissions are lighter than planetary gear racing transmissions. These countershaft racing transmissions are generally constant mesh transmissions having mechanical engagement devices, such as positive jaw clutches, that mechanically couple and uncouple components of the transmission to change the torque drive path through the transmission. These transmissions are sometimes referred to a “clutchless” transmissions because they do not use clutch packs that are used by planetary gear transmissions to change gear ratios. Countershaft transmissions have been used in racecars that have engines that, while producing significant power, do not produce more power than can be used to drive the racecar. A primary objective for equipment used in the driveline of such cars, including transmissions, is to consume as little power as possible and thereby make as much power as possible available to drive the racecar. These transmissions have been developed for and are used by racecars that use clutches to obtain significant control over the application of power to the transmission and to avoid loss of power typically required to drive a torque converter. While these clutches and countershaft transmissions differ considerably in design and construction from clutches and transmissions used in conventional automotive applications, they nevertheless comprise a conventional combination of a friction clutch and countershaft transmission. 
     Racecars that do not have engines that create very high power have used, and continue to use, torque converter driven modified planetary gear transmissions that were originally constructed for conventional automotive applications. The engines used by many such cars have become sufficiently powerful that modified conventional transmissions fail unacceptably frequently. Recently, devices have been developed to drive a planetary gear racing transmission by a torque converter. Those devices are driven by a torque converter, have a brake mechanism to selectively and reliably withhold and apply power to the transmission, and have been developed specifically for use with racing planetary gear transmissions. One such device is disclosed by U.S. Pat. No. 5,090,528, which is incorporated herein by reference and is assigned to the assignee of the invention that is the subject of this application. Another such device is disclosed by U.S. Pat. No. 5,050,716. These devices, in combination with racing planetary gear transmissions, more nearly resemble the conventional combination of a torque converter and planetary gear transmission than does the combination of a clutch and planetary gear transmission. 
     The combination of a torque converter drive and a planetary gear racing transmission provides a reliable and durable driveline combination. However, many racecars that use that combination do not use engines that produce the highest power and therefor do not require transmissions having components as large and strong as those of racing planetary gear transmissions. In addition, even racecars for which total weight is not a critical consideration, the weight of planetary gear racing transmissions is a disadvantage because the significant weight of the transmission is at a fixed location in the racecar and thereby limits the amount of weight that can be distributed to increase performance and handling of the racecar. Further, because of the size and durability of their components, racing planetary gear transmissions are significantly expensive components of a racecar. 
     The need therefor exists for a driveline combination that includes a torque converter drive and a transmission that is lighter and less expensive than combinations that include a racing planetary gear transmission and that is durable and reliable. The need also exists for such a combination further including a driveline brake that can be closely controlled to reliably apply power from the racecar engine to the driveline. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, the disadvantages of the driveline combination of a torque converter drive and a racing planetary gear transmission have been overcome. A combination is provided in which a torque converter drives a countershaft transmission. A releasable driveline brake may further be included in the combination to selectively withhold and then release power to the driveline of a racecar having the combination of this invention. 
     More particularly, the preferred combination of the present invention includes a torque converter to driveline coupler. That coupler includes a fluid pump adapted to provide fluid under pressure to a torque converter mounted to a flywheel that is mounted to an engine. The combination also includes a countershaft transmission. The coupler is adapted to engage an input shaft of the transmission and to drive the input shaft of the transmission from the torque converter. The countershaft transmission is preferably a constant mesh transmission. 
     Additionally, the torque converter to driveline coupler may include a fast-release brake that can prevent the coupler from driving the countershaft transmission when the engine is driving the torque converter. 
     Accordingly, an object of the present invention is to drive a countershaft transmission by a torque converter. 
     Another object of the present invention is to provide a combination of power transmission devices that is driven by a torque converter, allows manual changing of transmission ratios, and that consumes less power than previous torque converter drive and racing planetary gear transmission combinations. 
     Yet another object of the present invention is to provide a combination of power transmission components that is durable enough to withstand racing driveline loads and is less expensive than prior torque converter driven combinations. 
     These and other objects and advantages of the present invention, as well as details of the preferred embodiment thereof, will be more fully understood from the drawings and the following description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is an exploded view of a combination of a countershaft transmission and a torque converter to driveline coupler according to the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As illustrated by FIG. 1, drive combination  10  includes a torque converter to driveline coupler  12  and a countershaft transmission  14 . The torque converter to driveline coupler  12  is driven by a torque converter  20  that is mounted to a flywheel (not shown) that is mounted to a crankshaft of an engine (not shown). The torque converter to driveline coupler  12  has a transmission flange  26  defining a surface at an end of the torque converter to driveline coupler  12  opposite the torque converter. The transmission flange  26  is constructed to mate to a mounting flange of a transmission. The torque converter to driveline coupler  12  is preferably as described by U.S. Pat. No. 5,090,528. The construction and operation of the torque converter to driveline coupler  12  is described in that United States Patent, which has been incorporated by reference, and will not again be described. 
     The countershaft transmission  14  is preferably a transmission manufacture by Long Machine and Tool of Annville, Pa. The countershaft transmission  14  is depicted by FIG. 1 is a two speed transmission including a reverse gear. FIG. 1 includes an exploded view of countershaft transmission  14  that illustrates components essential to characterize the combination of the present invention. 
     The countershaft transmission  14  includes an upper case  18  and a lower case  22  that are joined together to form an enclosing case for the transmission. The upper case  18  includes a flange  24  and the lower case  22  includes a flange  28 . When upper case  18  and lower case  22  are joined, flanges  24  and  28  are positioned together to mate to transmission flange  26  of torque converter to driveline coupler  12 . As used herein to describe components of the countershaft transmission  14 , forwardly refers to a direction toward the torque converter to driveline coupler  12 , and rearwardly refers to an opposite direction. 
     Countershaft transmission  14  includes an input shaft  32 . An input bearing  34  is mounted to the input shaft  32 . A seat  35  is formed in a surface of a front wall  37  of the lower case  22  that meets a front surface (not shown) of the upper case  18  that is bounded by the flange  24 . A seat (not shown) in a front wall (not shown) of the upper case  18  is positioned opposite the seat  35 . The seat  35  and the seat in the front wall of the upper case  18  secure the input bearing  34  to the transmission case. The input shaft  32  has an input spline  36  extending towards the torque converter to driveline coupler  12  from the input bearing  34 . The input spline  36  extends forwardly from the countershaft transmission  14  to engage and be driven by the torque converter to driveline coupler  12 . The input spline  36  may engage and be driven by a component of the torque converter to driveline coupler  12 , such as the brake drum identified by U.S. Pat. No. 5,090,528 as 82. Alternatively, the input shaft  32  may extend through the torque converter to driveline coupler  12  to engage and be driven by the torque converter  20 . In that case, the input shaft also engages and drives components, including a brake, of the torque converter to driveline coupler  12 . 
     The input shaft  32  has a first gear mounting spline  38  extending rearwardly into the transmission  14  to an inner end  42 . A bore  44  extends into the input shaft  32  from the inner end  42 . A pilot bearing  48  is positioned within the bore  44 . An input drive gear  52  has an internally splined bore  54  that is sized to engage the mounting spline  38 . Input drive gear  52  includes gear section  56  forming a gear for power transmission that is adjacent to bearing  34 . Jaws  58  extend rearwardly from the input drive gear  52 . 
     Main shaft  62  has a pilot section  64  adjacent to a forward end  66 . Pilot section  64  is sized to be positioned within the pilot bearing  48  aligning the main shaft  62  with the input shaft  32 . A spline  68  extends rearwardly along main shaft  62  from pilot section  64 . The main shaft  62  defines a journal  72  rearwardly adjacent the spline  68 . A bearing  74  is mounted to the main shaft  62  rearwardly adjacent to the journal  72 . An output spline  76  extends along the main shaft  62  rearwardly from the bearing  74  to a rear end  78  of the main shaft  62 . The bearing  74  is received in seat  83  of the rear wall  84  of the upper case  18  and in seat  87  in the rear wall  88  of the lower case  22 . The output spline  76  extends rearwardly from the countershaft transmission case to drive a driveline component, such as a driveshaft (not shown). 
     A first gear  82  has a bore  85  sized to be positioned around the journal  72  of the main shaft  62 . The first gear  82  includes jaws  86  that extend along the main shaft  62  forwardly from the first gear  82 . 
     Slider sleeve  92  has an internally splined bore  94  sized to engage the spline  68  of the main shaft  62 . The slider sleeve  92  is thereby rotationally affixed to the main shaft  62 . The slider sleeve  92  has an external spline  96  extending along its length. 
     A high gear slider  102  has a bore  104  that is internally splined to slidably engage the external spline  96  of the slider sleeve  92 . The high gear slider  102  is thereby rotationally affixed to the slider sleeve  92  and through the slider sleeve  92  to the main shaft  62 . The high gear slider  102  includes jaws  106  that extend forwardly from high gear slider  102 . Jaws  106  are sized and constructed to positively engage the jaws  58  of the input drive gear  52  when the high gear slider  102  is advanced toward input drive gear  52 . A shifter groove  108  extends radially into high gear slider  102  around a circumference of the high gear slider  102  at a location rearward of the jaws  106 . The high gear slider  102  forms reverse gear  111  rearwardly adjacent to the shifter groove  108 . 
     A first gear slider  112  has a bore  114  that is internally splined to slidably engage the external spline  96  of the slider sleeve  92 . The first gear slider  112 , is thereby rotationally affixed to the slider sleeve  92  and through the slider sleeve  92  to the main shaft  62 . The first gear slider  112  includes jaws  116  that extend rearwardly from the first gear slider  112 . The jaws  116  are sized and constructed to positively engage the jaws  86  of the first gear  82  when the first gear slider  112  is moved rearwardly toward first gear  82 . A shifter groove  118  extends radially into first gear slider  112  around a circumference at a location forward of the jaws  116 . 
     A countershaft assembly  122  is positioned within the countershaft transmission case parallel to the input shaft  32  and the main shaft  62 . The countershaft assembly  122  has a front journal  124  at the forward extent of the countershaft assembly  122  and a rear journal  126  at the rearward extent of the countershaft assembly  122 . A front bearing  128  receives the front journal  124  and a rear bearing  130  receives the rear journal  126 . The front bearing  128  is received by a seat  132  in a surface of the front wall  37  of the lower case  22  that meets a front surface (not shown) of the upper case  18  that is bounded by the flange  24 . The front bearing  128  is also received in a seat (not shown) in the front wall (not shown) of the upper case  18  that is bounded by the flange  24 . The rear bearing  130  is received in a seat  134  formed in a surface of the rear wall  88  of the lower case  22  that meets the rear wall  84  of the upper case  18 . The rear bearing  130  is also received in a seat  136  formed in a surface of the rear wall  84  of the upper case  18  that meets the rear wall  88  of the lower case  22 . 
     The countershaft assembly  122  includes an input drive gear  142  that is rearwardly adjacent to the front journal  124 . The input drive gear  142  is positioned to mesh with and be driven by the input gear section  56 . The countershaft assembly  122  also includes a first drive gear  144  positioned forwardly adjacent to the rear journal  126 . The first drive gear  144  is positioned to mesh with and transmit power to the first gear  82 . The counter shaft assembly  122  further includes a reverse drive gear  146  that is positioned intermediate the input drive gear  142  and the first drive gear  144 . 
     A reverse idler gear  152  is rotatably mounted with an idler shaft  154  that is mounted within upper case  18  and positioned parallel to the main shaft  62  and the countershaft assembly  22 . The reverse idler gear is positioned to mesh with and be driven by the reverse drive gear  146  of the countershaft assembly  122 . The reverse idler gear is positioned rearward of the position of the high gear slider  102  at which the jaws  106  of the high gear slider  102  engage the jaws  58  of the input drive gear  52 . 
     A high gear fork  162  having arms  164  is positioned within the upper case  18  so that the arms  164  extend into the shifter groove  108  of the high gear slider  102 . A groove  166  extending generally perpendicular to the main shaft  62  is formed in an upper surface  168  of the high gear fork  102  that faces toward the upper case  18 . A high gear shifter arm  172  is positioned adjacent to the upper surface  168 . The shifter arm  172  has a journal  174  that extends into the groove  166 . The shifter arm  172  has a journal  176  that is parallel to the journal  174  and extends oppositely from the journal  174 . The journal  176  is offset a distance from the journal  174  in a direction that is generally perpendicular to the main shaft  62 . The journal  176  extends through a bore  178  in the upper case  18 . The portion of the journal  176  extending through the upper case  18  may be engaged by a shifter (not shown) to rotate the shifter arm  172  about the journal  176  thereby moving the journal  174 , the shifter fork  162 , and the high gear slider  102  along the slider sleeve  92 . 
     A first gear fork  182  having arms  184  is positioned within the upper case  18  so that the arms  184  extend into the shifter groove  118  of the first gear slider  112 . A groove  186  extending generally perpendicular to the main shaft  62  is formed in an upper surface  188  of the first gear fork  182  that faces toward the upper case  18 . A first gear shifter arm  192  is positioned adjacent to the upper surface  188 . The shifter arm  192  has a journal  194  that extends into the groove  186 . The shifter arm  192  has a journal  196  that is parallel to the journal  194  and extends oppositely from the journal  194 . The journal  196  is offset a distance from the journal  194  in a direction that is generally perpendicular to the main shaft  62 . The journal  196  extends through a bore  198  in the upper case  18 . The portion of the journal  196  extending through the upper case  18  may be engaged by a shifter (not shown) to rotate the shifter arm  192  about the journal  196  thereby moving the journal  194 , the shifter fork  182 , and the first gear slider  112  along the slider sleeve  92 . 
     Power is applied to the input shaft  32  by the torque converter to drive coupler  12 . The input drive gear  52  is driven by the input shaft  32 . The input drive gear  142  of the countershaft assembly  122  engages and is driven by the input drive gear  52 . The reverse idler gear  152  is driven by the reverse drive gear  146  of the countershaft assembly  122 . The first gear  82  is driven by the first drive gear  144 . 
     The main shaft  62  is driven only by the high gear slider  102  and the first gear slider  112 . The transmission ratio of the countershaft transmission  14  depends on the positions of the high gear slider  102  and the first gear slider  112 . 
     When the high gear slider  102  is moved toward the input gear  52  to the position at which the jaws  106  of the high gear slider  102  engage the jaws  58  of the input drive gear  52 , the main shaft is driven by the high gear slider  102  and rotates at the same speed as the input shaft  32 . When the high gear slider is moved rearwardly from the input drive gear  52  to a position at which the reverse gear  111  engages the reverse idler gear  152 , the main shaft  62  is rotated oppositely of the input shaft at a speed that results from the ratios of the input drive gear section  56  and the input drive gear  42 , the reverse drive gear  146  and the reverse gear  111 . When the high gear slider  102  is at a position between the input gear  52  and the reverse idler gear  152 , the high gear slider rotates with the main shaft  62  and does not drive the main shaft  62 . 
     When the first gear slider  112  is moved forwardly away from the first gear  82 , the first gear  82  freely rotates about the main shaft  62 . When the first gear slider  112  is move rearwardly to a position at which the jaws  116  of the first gear slider engage the jaws  86  of the first gear  82 , the first gear slider  112  rotates with the first gear  82 . The main shaft  62  is driven at a speed that depends on the ratio of the input drive gear section  56  and the input drive gear  142  and the ratio of the first drive gear  144  and the first gear  82 . 
     As will be appreciated by those of skill in the art, the present invention is not limited to the described embodiment. Modifications and variations of the present invention are possible in light of the teachings of this invention including, for example, use of a countershaft transmission having three or more forward gears. It should be understood that, within the scope of the appended claims, the invention may be practiced other than as described above.