CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application No. 62/195,448 filed July 22, 2015, the disclosure of which is incorporated in its entirety. Co-pending U.S. Patent Application No. 14/661,305 is incorporated by reference in its entirety, and is published as U.S. Publication No. 2015/0192204.

TECHNICAL FIELD

[0002] The technical field is generally related to multi-rail shifting mechanisms of manual compound transmissions, and particularly, an improved synchronizer for a manual compound transmission.

BACKGROUND

[0003] Manual compound transmissions are used for various vehicle applications. Such compound transmissions typically comprise a multiple speed main section containing a plurality of gears for various range and load gearing configurations.

[0004] Manual compound transmissions are generally positioned within a driveline adjacent a primary drive unit with at least one rotating drive shaft. These compound transmissions generally include a shifter or gear selector that extends from the transmission for interaction with an operator. The compound transmission may include a rotating and sliding assembly that is configured to engage a desired gear set when an operator moves the shifter or gear selector. Specifically, in a manual compound transmission an operator, through the gear selector, selects an appropriate gear by pushing or pulling the shift lever to a desired shift gate. A rail selector fixed to the main shift rail is configured to translate the movement of the shift lever to the shift forks. The rail selector is fixed to the main shift rail by a roll pin that extends through a central location of the rail selector. The action on the shift lever causes a set of shift rails to move at least one shift fork, which causes a shift collar or slider to slide over the appropriate rotating gear to synchronize and activate a desired gear range. [0005] Shift quality is an important factor for manual compound transmissions when selecting the desired gear range. When shifting from one gear to the next, depression of a clutch pedal causes separation of an output shaft from a countershaft, at which point two halves of the transmission are still turning at the same speed - albeit separately. The next gear up, however, is smaller than the previous gear and the second gear teeth are therefore moving faster than teeth of the slider. Thus, at this stage in a shift the next gear, countershaft, and input shaft are all turning too fast. Thus, without the use of a synchronizer, if the slider is moved over the next gear, the gears would grind together, causing noise, inefficient shifting, and wear of the gears.

[0006] Accordingly, synchronizers have been developed to reduce or eliminate grinding of gears during a shift. Thus, as a shifter is pulled (to shift from a first gear to a second gear), the slider pushes against synchronizer keys. The keys, in turn, push against a blocking ring which pushes the blocking ring into a cone-shaped part of the gear. As the cone-shapes engage, the blocking ring acts as a brake which grabs the gear and brings the components to the same rotational speeds. Thus, the two halves of the transmission are linked by friction of the cone-shaped surfaces. The frictional force is typically enough to bring the freely floating components to the same speed, but is not sufficient to drive the vehicle.

[0007] Keys and notches in the blocking ring have teeth that are aligned with teeth of the gear. Thus, in continuing the shift, the shifter is pushed into gear which causes the slider ride along the teeth on the blocking ring, using them to align the teeth on the slider with the gear teeth. This prevents misalignment so that the shifter can slide into gear easily and without grinding. Once the components are aligned, the clutch is released and power from the input shaft can transmit through the transmission.

[0008] When shifting between gears, however, the sliding sleeve engages blocking rings separately from one another. That is, the sliding sleeve is positioned in a first location to engage a first blocking ring with a first cone. During the shift the sliding sleeve shifts axially to disengage the first blocking ring from the first cone at the first location, before engaging a second blocking ring with a second cone of the second gear. In order to do so, the sliding sleeve passes through a neutral location, which is a location where neither of the blocking rings is engaged with their respective gear cones. Such operation is inefficient in that each shift thereby includes a power interrupt during which the de -engagement occurs before the engagement of the cones in the next gear occurs. Such a design is also spatially inefficient as well, in that additional stroke is used to pass through the neutral position.

[0009] Therefore, it is desirable to provide a manual compound transmission system that allows for improved synchronization of the meshing components.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG. 1 is a perspective view, not to scale, of a compound manual transmission with the case partially torn away;

[0011] FIG. 2 is a perspective view of an exemplary shift rail for a compound manual transmission;

[0012] FIG. 3 is a partial section view of an exemplary rotating assembly;

[0013] FIG. 4 illustrates an exploded view of an exemplary synchronizer for an exemplary manual compound transmission;

[0014] FIG. 5 is a perspective view of a cross-section of a synchronizer assembly that includes a compact boosted synchronizer;

[0015] FIG. 6 illustrates a cross-section of the compact boosted synchronizer of FIG. 5;

[0016] FIG. 7 illustrates a plan view of the compact boosted synchronizer of FIG. 5; and

[0017] FIGS. 8A-8E illustrate steps in a synchronizer operation having both cross- sectional views and plan views of exemplary steps.

DETAILED DESCRIPTION

[0018] Referring now to the discussion that follows and also to the drawings, illustrative approaches to the disclosed systems and methods are shown in detail. Although the drawings represent some possible approaches, the drawings are not necessarily to scale and certain features may be exaggerated, removed, or partially sectioned to better illustrate and explain the present disclosure. Further, the descriptions set forth herein are not intended to be exhaustive or otherwise limit or restrict the claims to the precise forms and configurations shown in the drawings and disclosed in the following detailed description. [0019] Reference in the specification to "an exemplary illustration" and "example" or similar language means that a particular feature, structure, or characteristic described in connection with the exemplary approach is included in at least one illustration. The appearances of the phrase "in an illustration" or similar type language in various places in the specification are not necessarily all referring to the same illustration or example.

[0020] According to various exemplary illustrations described herein, a system is disclosed. Specifically, an exemplary synchronizer for a compound manual transmission is disclosed. The compound manual transmission includes an input shaft and an output shaft, the input shaft may be configured to engage a prime mover (not shown), while the output shaft may include a yoke for engaging a drive member (not shown). The compound manual transmission includes a main shaft, a countershaft and a plurality of gears configured with in the transmission housing. The main shaft may be configured between the input shaft and the end yoke, which may be configured at a rear of the compound manual transmission. The main shaft may include a first plurality of gears configured about the main shaft and in rotative alignment with a second plurality gears configured on the countershaft. The shafts and gears are typically referred to as the rotating assembly.

[0021] A shift lever may extend from a control tower configured on a shift bar housing, which may be attached to an upper section of the compound transmission housing. The shift bar housing may be configured to position at least one shift rail in proximity to the rotating assembly, thereby slidably connecting the shift lever and at least one shift fork to the rotating assembly. The at least one shift rail may be configured with at least one damping element for the reduction or elimination of notch, nibble or other issue that may create poor shift quality. The damping element may be in the form of a spring, a low friction bushing, linear ball bearing or other known damping element that may be configured on the at least one shift rail. The connection between the shift lever and the rotating assembly allows for an operator to select a desired gear set as the lever may be directly connected to the gears within the compound transmission. The at least one shift rail may include a rail selector and the at least one damping element configured on a main shift rail of the at least one shift rail. Through movement of the at least one shift rail, the shift fork may engage at least one synchronizer, discussed in greater detail below, for meshing the selected gear set, which helps to prolong the life of the compound transmission and minimize nibble that may be associated with gear changing. [0022] The rotating assembly, which includes the input shaft, main shaft, countershaft and synchronizer, may be configured to transmit torque from the prime mover to the output yoke through the desired gear set. The main shaft may include a plurality of splined teeth that may be configured to engage a fixed hub of the synchronizer and ultimately the plurality of gears on the counter shaft, which may be driven by the input shaft. The synchronizer may include at least one gear flange, at least one blocker or synchronizer ring, the fixed hub, a sliding sleeve and a pre-energizer component. The flange, blocker, ring and hub all include teeth or cogs cut into an outer diameter surface of each and these teeth are configured to engage and mesh with corresponding teeth or cogs that are cut into an inner diameter surface of the sliding sleeve. The teeth each have engagement chamfers that aid in the alignment with corresponding chamfers on the sliding sleeves teeth. Thus, in operation, when the chamfers are indexed/aligned, and a synchronization phase starts. Additionally, the pre- energizer component may include at least one of a strut, a roller, a plunger and a spring.

[0023] Typically, when the sliding sleeve moves aside it pushes, via the strut or pre- energizer, the blocker ring against the targeted gear. When pushed against a desired gear cone, the blocker ring rotates (due to friction) until meeting a wall of the fixed hub. At this position, an engagement chamfer may be aligned to a chamfer configured on the teeth of the sliding sleeve. Thus, with the chamfers indexed/aligned, synchronization starts. Once completed, the synchronization, blocker ring and sliding sleeve are meshed (via chamfers), which releases the sliding sleeve for advancing toward the gear. The sliding sleeve and gear cone spline hit each other and again the splines are meshed due to the action of engagement between the chamfers, thereby completing the engagement. Thus, in operation, and operator positions the shift lever to select a predetermined gear set. The gear selection occurs by maneuvering the shift lever to slide the main shift rail, thereby connecting the shift rail with the synchronizer and ultimately the gears. The rail selector provides a linear force that pushes or pulls the shift fork, thereby sliding at least a portion of the shift fork against an outer engagement groove on the outer diameter of the sliding sleeve to synchronize and engage the desired gear set.

[0024] The disclosed system improves a shift effort using a synchronizer that includes a boost ramp and a system architecture that makes possible a synchronization that starts immediately after the opposite gear disengagement. This eliminates a neutral position, reducing the overall axial length as a result. [0025] Referring to FIG. 1 an exemplary compound manual transmission 100 is illustrated. The transmission 100 may comprise an input shaft 110 and an output shaft 112, input shaft 110 may be configured to engage a prime mover (not shown), while output shaft 112 may include a yoke 114 for engaging a driven member (not shown). Compound manual transmission 100 includes an output shaft main shaft 116, a countershaft 118 and a plurality of gears 120, 122 configured about shafts 116, 118. Main shaft 116 and countershaft 118 are configured within a transmission housing 124 between and engagement with input shaft 110 configured to extend forward of transmission housing 124 and end yoke 114 configured to extend aft of transmission housing 124. Main shaft 116 may include plurality of gears 120 configured about main shaft 116 and rotatably aligned with plurality of gears 122 configured on countershaft 118. Input shaft 110, output shaft 112, main shaft 116 and countershaft 118 may be supported by housing 124 through a plurality of bearings. Main shaft 116 may include at least one synchronization unit or synchronizer 126 for engaging a predetermined output speed.

[0026] With continued reference to FIG. 1, an upper housing portion 128 may be configured to receive a shift bar housing 130. Additionally, a control tower 132 extends from shift bar housing 130 to a shift lever 134. Control tower 132 may include a cross joint with axial adjustment elements to increase shift selection while reducing any free play in shift lever 134. Shift bar housing 130 may be configured to retain and align a gear change control system 136. Control system 136 may be configured to translate movement from shift lever 134 to at least one shift fork 138 (138', 138") to select a desired gear set from plurality of gears 120, 122 for determining an output. Additionally, shift fork 138 may be configured to engage at least a portion of synchronizer 126 for selecting the gear set.

[0027] FIG. 2 illustrates a detail view of control system 136, which may include at least one main shift rail 210. Main shift rail 210 may include a first end portion 212, a mid-portion 214 and a second end portion 216. As illustrated, control system 136 includes a plurality of shift rails. Specifically, a shift rail 218, a shift rail 220 and a shift rail 222. However, this illustration is merely an example and any number of shift rails may be used. Additionally, each shift rail 218, 220, 222 may include a respective shift fork 138, 138', 138" as shown. Main shift rail 210 may include an engagement mechanism 230 and a rail selector damping assembly 260. [0028] Engagement mechanism 230 may be used for interconnecting shift lever 134 with main shift rail 210. Engagement mechanism 230 may be configured on either main shift rail first end 212 or main shift rail second end 216 depending on the particular position of control tower 132. Engagement mechanism 230 may be configured to receive an end of shift lever 134 and may include at least one adjustment mechanism 240. Adjustment mechanism 240 may be configured on at least one side of engagement mechanism 230 to aid in minimizing or eliminating free play while improving shift quality. Additionally, control tower 132 may include a cross joint to also help with increasing gear selection while reducing or eliminating the free play. Adjustment mechanism 240 may include a spring biasing member or detent plunger 242 configured to bias travel of engagement mechanism 230 to improve shift definition and reduce free play of shift lever 134, and adjustment mechanism 240 may include a bias plate 246 having grooves and channels replicating a bias pattern for shift lever travel allowing engagement mechanism 230 to maintain a defined shift pattern.

[0029] Turning now to FIG. 3, an exemplary rotating assembly 300 is illustrated and into which the current disclosure is incorporated. That is, for the purposes of illustration, discussion with respect to FIG. 3 includes a known synchronizer operation, having an operation that is spatially inefficient in that the operation includes passing from a first gear engagement and through a neutral position before engaging a second gear.

[0030] Rotating assembly 300 includes input shaft 110 operatively connected to output shaft 112 either directly or indirectly through countershaft 118. Rotating assembly 300 may further include first plurality of gears 120, second plurality of gears 122 and at least one synchronizer 126, 126', 126". Input shaft 110 includes a first end 302 for engaging the prime mover (not illustrated) and a second hollow end 304 having an input gear 306 configured on end 304, and a pocket bearing 308 positioned in end 304. Pocket bearing 308 is configured to support main shaft 116 at a forward end 310 and a bearing 312 supports main shaft 116 at an aft end 314. An exterior of input gear 306 is configured to engage a forward gear 316 on countershaft 118. Input shaft 110 may be supported in housing 124 by a bearing 318, while output shaft 112 may be supported in housing 124 by pocket bearing 308 and bearing 312. Counter shaft 118 may be separately supported by a forward bearing 320 and an aft bearing 322 configured in housing 124. Bearings 308, 312, 318, 320, and 322 are not limited to a specific type or size, but may include taper, thrust, roller, ball, needle or other type of known bearing. [0031] Countershaft 118 may also include a forward mid-gear 324, an aft mid-gear 326 and an aft gear 328, all of which may be fixedly connected to countershaft 118. Thus, the second plurality of gears 122 may include forward gear 316, forward mid-gear 324, aft mid- gear 326 and aft gear 328. Second plurality of gears 122 may be configured to transmit torque from input shaft 110 to first plurality of gears 120, which may include a main forward gear 330, a main mid-gear 332 and a main aft gear 334 rotatively attached to main shaft 116. Gears 330, 332, and 334 may include a roller bearing 336 configured between gears 330, 332, and 334 and the main shaft 116. Roller bearing 336 may be a needle bearing that allows gears 330, 332, and 334 to rotate about main shaft 116. Thus, first plurality of gears 120 are in rotative alignment with countershaft 118 and second plurality of gears 122. The number of gears used is not limited to a specific set, but determined by the size and design of the transmission. Gears 120, 122 may be of any known gear design and are illustrated as helical gears.

[0032] Plurality of gears 120, 122 transmit torque from input shaft 110 to yoke 114 configured on main shaft 110 at the rear of transmission 100. Thus, a torque flow path may be defined through an interaction between the input gear 306 meshing with either forward gear 316, to transmit through countershaft 118, or through a gear flange 338 of synchronizer 126, to transmit directly through main shaft 110. FIG. 3 illustrates that rotating assembly 300 is not limited to the number of synchronizers 126 used to transmit that torque, as a forward synchronizer 126' and an aft synchronizer 126" may be included to provide additional torque paths through countershaft 118 and main shaft 116. Synchronizers 126', 126" engage main shaft 116 through a splined connection. Specifically, main shaft 116 includes a forward spline and a mid-spline 342 for transmitting torque from synchronizers 126', 126" and through main shaft 116 to ultimately transmit rotational torque out through yoke 114. Merely for demonstrational purposes, a general description of synchronizer 126 will be discussed in greater detail below.

[0033] Referring to FIGS. 3 and 4, the exemplary synchronizer 126 and its operation will now be discussed in greater detail. Synchronizer 126 may be included to provide a smooth transition between the different shift phases and gear selections within compound manual transmission 100. Synchronizer 126 may be configured to eliminate the "nibble" effect found when changing gears and, which may be felt in shift lever 134 by an operator. As illustrated in FIG. 4, synchronizer 126 may include a fixed synchronization hub 400 positioned between two blockers or synchronizing rings 402. Synchronization hub 400 and synchronizing rings 402 are positioned between two separate gear flanges 404. Gear flanges 404 and

synchronization hub 400 both include internal splines 406, 408. Specifically, synchronization hub 400 includes internal splines 406, which are configured to engage at least one of splines 340, 332 on main shaft 116. Gear flanges 404 include internal splines 408, which engage with a corresponding spline cut into an edge of the plurality of gears 120. Splines 340, 332 provide a positive engagement between the rotating components to transmit torque, as previously discussed.

[0034] Additionally, synchronization hub 400, synchronization rings 402, and gear flanges 404 all include external gear teeth 410 or other known drive feature on an outer surface of each. External gear teeth 410 may engage corresponding features or internal gear teeth 412 on an internal surface of a sliding sleeve 414. Internal gear teeth 412 may be provided on an inner diameter 416 of sliding sleeve 414, while a circumferential groove 418 may be configured in an outer surface 420 of sliding sleeve 414 for receiving a portion of shift fork 138. Sliding sleeve internal gear teeth 412 may be configured to mesh with and be positioned radially about synchronization hub 400, synchronization rings 402, and gear flanges 404. Gear teeth 410, 412 may be configured with reduced radial clearance to improve notchness when sliding sleeve 414 starts to engage gear flange 404.

[0035] In operation, sliding sleeve 414 engages one of synchronization rings 402 when shifted axially by used of shift fork 138 within circumferential groove 418. That is, during a gear shift, sliding sleeve 414 is caused to move, as an example, in a first direction 420, and internal gear teeth 412 of sliding sleeve 414 engage external gear teeth 410 of

synchronization hub 400. Continued motion of sliding sleeve 414 causes slight

circumferential motion and alignment of synchronization ring 402 via gear teeth 410 of synchronization ring 402, such that external gear teeth 410 of gear flange 404 are likewise aligned. Continued motion of sliding sleeve 414 thereby locks hub 400 with gear flange 404, such that sliding sleeve 414 thereby carries torque from main shaft 116, to synchronization hub 400, through sliding sleeve 414, and to gear flange 404. In such fashion synchronization ring 402 serves to align external teeth 410 of synchronization hub 400 and flange 404, preventing damage from occurring thereto. Traditionally, synchronization ring 402 is fabricated of a soft material such as brass, which ensures that wear will occur in synchronization ring 402 and not in the more expensive synchronization hub 400 or flange 404.

[0036] When shifting to another gear, such as the other flange 404 toward the aft of the transmission, the above description is reversed and sliding sleeve 414 is caused to move in a second direction 422, causing flange 404 to disengage from synchronization hub 400, pass through a neutral position with sliding sleeve 414 positioned at a central location with respect to each gear flange 404, and then continued motion of sliding sleeve 414 causes sliding sleeve 420 to engage the other flange 404 (also labeled as flange 424 for clarity) in the same fashion and using the other synchronization ring 402 (also labeled as synchronization ring 426 for clarity).

[0037] Referring now to FIG. 5, a perspective view of a cross-section of an assembly 500 that includes a disclosed compact boosted synchronizer is illustrated, which may be incorporated into a transmission such as compound manual transmission 100. Assembly 500 includes a hub 502 and a slide sleeve 504. Hub 502 is generally cylindrical in shape, having a central axis or defining an axial direction 558, the hub extending in a circumferential direction 544. Assembly 500 also includes a first synchronizer cone 506 and a second synchronizer cone 508. First and second synchronizer cones 506, 508 may also be referred to as "dog bodies" in the art. Assembly 500 includes a first synchronizer ring 510 and a second synchronizer ring 512. Assembly 500 shows in its cross-section a pack or set of components 514, as will be further discussed in FIG. 6. Components 514 may be employed to effect a synchronization as will be further illustrated, and it is contemplated that components 514 may be distributed about a circumference of assembly 500 at two, three, or more locations.

[0038] First and second synchronizer rings 510, 512 include angled conical surfaces 554, 556 as shown that correspond, mate, and engage with angled conical surfaces 550, 552 of first and second synchronizer cones 506, 508. The angled surfaces are generally smooth and engage one another during the synchronization process. That is, first synchronizer ring 510 presses against first synchronizer cone 506 when pressure is applied to first synchronizer ring 510 and to the left in the figure, and second synchronizer ring 512 presses against second synchronizer cone 508 when pressure is applied to second synchronizer ring 512 and to the right in the figure. This factional operation enables to each respective cone and ring to come to the same speed during operation, as will be further described. [0039] FIG. 6 illustrates a cutaway of components 514, and FIG. 7 illustrates a perspective view of components 514. FIG. 7, however, shows a view that also does not include slide sleeve 504 (or an insert), as will be further discussed, such that the operation of components 514 can be visualized. Referring to both FIGS. 6 and 7, and FIG. 5 as well, torque is transferred from hub 502 to one of first synchronizer cone 506 and second synchronizer cone 508, via slide sleeve 504, depending on the engagement of components 514. Synchronization rings 510, 512 are fabricated, in one example, of a soft material such as brass, which ensures that wear will occur in synchronization rings 510, 512 and not in the more expensive hub 502 or synchronizer cones 506, 508. Synchronizer cones 506, 508 each include a generally L-shaped cross-section that oppose one another, each having respective bases 511, 513 and legs 515, 517. Each leg 515, 517 includes respective gear teeth 546, 548 at a given pitch and at a free outer edge thereof. Synchronization rings 510, 512 are positioned or axially contained within slots 519, 521 of an inner lock 530. Components 514 include a spring support 516, a biasing member or spring 518 positioned therein, and a strut pin 520 (strut pin 520 not shown in FIG. 7). Slide sleeve 504 includes a circumferential groove 522, which corresponds with circumferential groove 418 for engagement with shift fork 138. Groove 522 includes a slot 524, into which an insert 526 fits. Insert 526 includes a pair of slight grooves or dimples 528 that engage with strut pin 520 for various stages of operation of components 514. Inner lock 530, shown in the cross-section of FIG. 6, but also visible in the cutaway/perspective view of FIG. 7, includes angled and opposing engagement surfaces 532. Hexagonal headed pins 534 include surfaces that engage against surfaces of inner lock 530, including angled engagement surfaces 532 of inner lock 530, and pins 534 extend radially inward from insert 526. Hub 502 includes opposing boosted ramps 536 and 538 that are defined on and extend radially inward from an external surface of hub 502, the boosted ramps 536 and 538 configured to engage with pins, such as hexagonal headed pins 534 during operation. As shown, boosted ramps 536 and 538 are at oblique angles with respect to circumferential direction 558, as well as with respect to the axial direction 558.

[0040] Components 514 engage as follows, during operation and axial movement of slide sleeve 504. As shown in FIGS. 5, 6, and 7, slide sleeve 504 is positioned such that torque transfer occurs from hub 502, to slide sleeve 504 via gear teeth 540 that are at the same given pitch as gear teeth 546, 548 and on an external surface of hub 502, as well as gear teeth 542 on an internal surface of slide sleeve 504, to first synchronizer cone 506. Gear teeth 546 and 548 on an external circumference of each of first and second synchronizer cones 506, 508 are also engageable with gear teeth 542 on the internal surface of slide sleeve 504. Accordingly, it is understood that gear teeth 542 have a relationship having comparable spacing and angular orientation such that gear teeth 542 engage with gear teeth 540 of hub 502, and with gear teeth 546, 548 during the disclosed synchronization operation. Thus, motion of slide sleeve 504 in axial direction 558 causes insert 526 having pins 534 to move axially 558 as well, forcing engagement of pins 534 against boosted ramps 536, 538, and with a corresponding angled engagement surface 532 of inner lock 530, causing inner lock 530 to engage the other of synchronization rings 510, 512. Accordingly, each synchronization ring 510, 512 has a limited axial degree of freedom to move axially 558 while engaging one of and disengaging the other of synchronization rings 510, 512.

[0041] Synchronization occurs during a number of steps that are illustrated in FIGS. 8A- 8E. Each of FIGS. 8A-8E include a side or cutaway view and a corresponding plan view above the cutaway view. Each plan view of FIGS. 8A-8E is a plan view of the components that are visible in FIG. 7, in which slide sleeve 504 and insert 526 are not shown so that the components underneath are visible.

[0042] FIG. 8A corresponds to the position of components as illustrated in FIGS. 5, 6, and 7, and corresponds with engagement of hub 502 with first synchronizer cone 506. That is, torque transfer in FIG. 8A is from hub 502, through slide sleeve 504, to first synchronizer cone 506. Second synchronizer cone 508 is not engaged and therefore there is relative speed between the two, as illustrated.

[0043] Disengagement of first synchronizer cone 506, and engagement of second synchronizer cone 508 begins in FIG. 8B. That is, slide sleeve 504 is shifted to the right in FIG. 8B during engagement of shift lever 134 via an operator, and as can be seen, slide sleeve 504 is at an axial location that is disengaged from first synchronizer cone 506. Movement of slide sleeve 504 likewise moves insert 526, which thereby causes pins 534 to axially shift as well. In the illustrated axial location, strut pin 520 is engaged with the first of dimples 528. As seen in the top view of FIG. 8B, the system is pre-energized and pin 534 labeled in FIG. 8B begins to ride along boosted ramp 536, causing insert 526 to move axially via pressure on pin 534. [0044] Synchronization continues in FIG. 8C. Hexagonal pin 534 engages against angled engagement surface 532 of inner lock 530, and also is engaged against boosted ramp 536. The axial movement of inner lock 530 causes reduced pressure between first synchronizer ring 510 and first synchronizer cone 506. Continued movement of slide sleeve 504 toward the right in the figures causes a circumferential shift of insert 526, within slot 524 as seen in FIG. 6, because second synchronizer ring 512 blocks insert 526 from any axial motion by pressing against second synchronizer cone 508. The circumferential shift, because of the pressure between second synchronizer ring 512 and second synchronizer cone 508, thereby also causes second synchronizer cone 508 to shift circumferentially, which enables gear teeth 548 on second synchronizer cone 508 to come into alignment with gear teeth 542 upon further axial shift.

[0045] Continued axial motion of slide sleeve 504 increases pressure between second synchronizer ring 512 and second synchronizer cone 508, while adding additional pressure between second synchronizer ring 512 and second synchronizer cone 508. The additional pressure arrests or reduces relative motion between slide sleeve 504 and second synchronizer cone 508. As such, with the relative motion between slide sleeve 504 and second synchronizer cone 508 stopped, and with gear teeth 548 on second synchronizer cone 508 aligned with gear teeth 542 of slide sleeve 504, slide sleeve 504 may slide its final distance (not shown in the Figures) to engage gear teeth 542 with gear teeth 548. In such fashion, the synchronization (and gear shift) is complete, with second synchronizer cone 508 engaged with slide sleeve 504, which is engaged with hub 502.

[0046] Thus, disclosed is compound transmission shift mechanism or assembly 500 that includes hub 502 that receives power from input shaft 110. The hub 502 includes external gear teeth 540 extending in circumferential direction 544, the hub 502 having two boosted ramps 536, 538 that extend on an external surface of the hub 502. First and second synchronizer cones 506, 508 each have external gear teeth 546, 548. Legs 511, 513 of each synchronizer cone 506, 508 includes an angled external surface 550, 552. The first and second synchronizer rings 510, 512 include angled surfaces 554, 556 that mate with the angled surfaces 550, 552 of the first and second synchronizer cones 506, 508. A slide sleeve 504 includes a gear teeth 542 on an inner surface thereof, the gear teeth 542 of the slide sleeve 504 is engageable with the external gear teeth 546, 548 of the first and second synchronizer cones 506, 508, and gear teeth 542 are engageable with the gear teeth 540 on the outer circumference of the hub 502, the slide sleeve 504 having a slot 524 in groove 522. Inner lock 530 contains each of the first and second synchronizer rings 510, 512, causing the first and second synchronizer rings 510, 512 to move in axial direction 558 when axial pressure is applied to the inner lock 530. Insert 526 is positioned within the slot 524, the insert 526 having pins 534 extending therefrom. Strut spring 518 is configured to exert a force of strut pin 520 against the insert 526.

[0047] When the slide sleeve 504 is shifted in the axial direction 558, the hub 502 disengages its gear teeth 540 with the first synchronizer cone 506, the insert 526 moves axially 558 to engage one of the pins 534 of the insert 526 with one of the surfaces 532 of the inner lock 530, the one pin 534 rides along one of the two boosted ramps 536 of the hub 502 causing a circumferential 544 shift of the insert 526, causing the angled surface 556 of the second synchronizer ring 512 to frictionally engage against the angled surface 552 of the second synchronizer cone 508, causing the second synchronizer ring 512 and the second synchronizer cone 508 to rotate at the same speed, such that the slide sleeve 504 can be further axially positioned over both the gear teeth 540 of the hub 502 and the gear teeth 548 of the second synchronizer cone 508.

[0048] With regard to the processes, systems, methods, heuristics, etc. described herein, it should be understood that, although the steps of such processes, etc. have been described as occurring according to a certain ordered sequence, such processes could be practiced with the described steps performed in an order other than the order described herein. It further should be understood that certain steps could be performed simultaneously, that other steps could be added, or that certain steps described herein could be omitted. In other words, the descriptions of processes herein are provided for the purpose of illustrating certain embodiments, and should in no way be construed so as to limit the claimed invention.

[0049] Accordingly, it is to be understood that the above description is intended to be illustrative and not restrictive. Many embodiments and applications other than the examples provided would be apparent upon reading the above description. The scope of the invention should be determined, not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. It is anticipated and intended that future developments will occur in the technologies discussed herein, and that the disclosed systems and methods will be incorporated into such future embodiments. In sum, it should be understood that the invention is capable of modification and variation.

[0050] As such, the disclosed system improves a shift effort using a synchronizer that includes a boost ramp and a system architecture that makes possible a synchronization that starts immediately after the opposite gear disengagement. This eliminates a neutral position, reducing the overall axial length as a result.

[0051] All terms used in the claims are intended to be given their broadest reasonable constructions and their ordinary meanings as understood by those knowledgeable in the technologies described herein unless an explicit indication to the contrary in made herein. In particular, use of the singular articles such as "a," "the," "said," etc. should be read to recite one or more of the indicated elements unless a claim recites an explicit limitation to the contrary.

[0052] Reference in the specification to "one example," "an example," "one approach," or "an application" means that a particular feature, structure, or characteristic described in connection with the example is included in at least one example. The phrase "in one example" in various places in the specification does not necessarily refer to the same example each time it appears.

[0053] The present disclosure has been particularly shown and described with reference to the foregoing illustrations, which are merely illustrative of the best modes for carrying out the disclosure. It should be understood by those skilled in the art that various alternatives to the illustrations of the disclosure described herein may be employed in practicing the disclosure without departing from the spirit and scope of the disclosure as defined in the following claims. It is intended that the following claims define the scope of the disclosure and that the method and apparatus within the scope of these claims and their equivalents be covered thereby. This description of the disclosure should be understood to include all novel and non-obvious combinations of elements described herein, and claims may be presented in this or a later application to any novel and non-obvious combination of these elements.

[0054] Moreover, the foregoing illustrations are illustrative, and no single feature or element is essential to all possible combinations that may be claimed in this or a later application. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. The invention may be practiced otherwise than is specifically explained and illustrated without departing from its spirit or scope. The scope of the invention is limited solely by the following claims.