Gear shifting system

Abstract

A transmission system (300) including a first gear selector assembly (329), the first gear selector assembly (329) including a first selector ring (54) and a second selector ring (56), the first and second selector rings (54, 56) being translatable relative to one another, the first selector ring (54) including a first set of engagement members (45) secured to one another by a first annular member (53), each engagement member (45) of the first set including a first portion (59) located on a first side of the first annular member (53) and a second portion (61) located on a second side of the first annular member (53), each first portion (59) having a first drive surface (67) oriented generally in a first rotational direction and a first non-drive surface (69) oriented generally in a second rotational direction, each second portion (59) having a first drive surface (67) oriented generally in a first rotational direction and a second non-drive surface (69) oriented generally in a second rotational direction. a second selector ring (56) including a second set of engagement members (46) secured to one another by a second annular member (55), each engagement member (46) of the second set including a first portion (63) located on a first side of the second annular member (55) and a second portion (71) located on a second side of the second annular member (55), each first portion (69) having a first drive surface (67) oriented generally in the second rotational direction and a first non-drive surface (69) oriented generally in the first rotational direction, each second portion (71) including a second drive surface (67) oriented generally in the second rotational direction and a second non-drive surface (69) oriented generally in the first rotational direction.

Description

[Technical Field]

[0001] The present invention relates to a transmission system. [Background technology]

[0002] In a conventional single-clutch synchromesh transmission system for a vehicle, the transmission must be disengaged from a power source, such as an engine or motor, by operating a clutch before the current gear is deselected and a new gear is engaged. If power is not disengaged when attempting to engage a new gear, the synchromesh device either cannot engage the new gear element or must be forced to engage it, risking damage to the transmission and creating a torque spike in the transmission. This is most often because the engine's RPM does not match the RPM of the new gear. For vehicles such as automobiles with conventional gearboxes and engine-powered engines, selecting a new gear ratio typically takes 0.5 to 1 second to complete. Therefore, when a higher gear is selected, for example, a time delay allows the engine (through its own inertia) to reduce RPM to more closely match the RPM of the new gear before the clutch reconnects the engine and transmission, thereby reducing the likelihood of a torque spike when power is reapplied.

[0003] Dual Clutch Transmission (DCT) systems have attempted to address this issue by using two clutches to seamlessly transfer torque when shifting between gears. However, DCTs have a number of drawbacks, including the need to use two heavy and expensive friction clutches, which are complex to control and have parasitic losses, making them less efficient.

[0004] Another type of seamless transmission system is called an instantaneous-type transmission system. This group of transmission systems includes at least one selector assembly, which includes first and second sets of engaging elements arranged to selectively engage a drive mechanism with the or each gear element associated therewith. In some instantaneous transmission systems, the first and second sets of engaging elements are arranged to allow a new gear to be selected while the current gear is still engaged, thereby allowing the new gear to be selected under the power of several shift types. Typically, at least one selector assembly in an instantaneous transmission system has four modes of operation with the or each rotatably mounted gear element associated therewith: fully engaged in both torque directions (fully engaged); disengaged in both torque directions (neutral); engaged in the direction of positive torque and disengaged in the direction of reverse torque; and engaged in the direction of reverse torque and disengaged in the direction of positive torque.

[0005] It is in the last two modes that discrete ratio gearboxes can instantly shift ratios up or down under load without interrupting torque. Instantaneous shifting is described in WO 2004 / 099654, WO 2005 / 005868, WO 2005 / 005869, WO 2005 / 024261 and WO 2005 / 026570, WO 2006 / 095140, WO 2006 / 123128, WO 2006 / 123166, WO 2007 / 132209, WO 2008 / 062192, WO 2008 / 096140, WO 2008 / 145979, WO 2009 / 068853, WO 2010 / 046654, WO 2010 / 046655, WO 2010 / 046652, WO 2012 / 164237, WO 2020 / 128412, WO 2020 / 183118 and WO 2021 / 156585, the contents of which are incorporated by reference. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2004 / 099654 [Patent Document 2] International Publication No. 2005 / 005868 [Patent Document 3] International Publication No. 2005 / 005869 [Patent Document 4] International Publication No. 2005 / 024261 [Patent Document 5] International Publication No. 2005 / 026570 [Patent Document 6] International Publication No. 2006 / 095140 [Patent Document 7] International Publication No. 2006 / 123128 [Patent Document 8] International Publication No. 2006 / 123166 [Patent Document 9] International Publication No. 2007 / 132209 [Patent Document 10] International Publication No. 2008 / 062192 [Patent Document 11] International Publication No. 2008 / 096140 [Patent Document 12] International Publication No. 2008 / 145979 [Patent Document 13] International Publication No. 2009 / 068853 [Patent Document 14] International Publication No. 2010 / 046654 [Patent Document 15] International Publication No. 2010 / 046655 [Patent Document 16] International Publication No. 2010 / 046652 [Patent Document 17] International Publication No. 2012 / 164237 [Patent Document 18] International Publication No. 2020 / 128412 [Patent Document 19] International Publication No. 2020 / 183118 [Patent Document 20] International Publication No. 2021 / 156585 Summary of the Invention

[0007] In some situations, it is desirable to package an instantaneous shifting system in the most efficient manner possible. The inventors have determined that by redesigning the gear selector assembly actuator system, it is possible to improve the packaging of the shifting system and reduce the number of actuator components required.

[0008] Another problem with known instantaneous shifting systems is that in at least one selector assembly, the gear selector rings are oppositely oriented, thus requiring separate tooling to manufacture the first and second gear selector rings, which undesirably adds additional manufacturing cost and time.

[0009] SUMMARY OF THE INVENTION It is therefore an object of the present invention to alleviate at least one of the aforementioned problems, or at least to provide a transmission system that replaces existing transmission systems.

[0010] According to a first aspect of the present invention, there is provided a transmission system as set forth in claim 1. The present invention provides an instantaneous type transmission system including a selector assembly, wherein the first and second selector rings may be identical.

[0011] In accordance with another aspect, a transmission system is provided.

[0012] The transmission may include a first gear selector assembly. The first gear selector assembly may include a first selector ring. The first gear selector assembly may include a second selector ring. The first and second selector rings may be translatable relative to one another.

[0013] The first selector ring can include a first set of engaging members secured to one another by a first annular member. Each engaging member of the first set can include a first portion located on a first side of the first annular member and a second portion located on a second side of the first annular member. Each first portion can have a first drive surface oriented generally in the first rotational direction. Each first portion can have a first non-drive surface oriented generally in the second rotational direction. Each second portion can have a second drive surface oriented generally in the first rotational direction. Each second portion can have a second non-drive surface oriented generally in the second rotational direction.

[0014] The second selector ring can include a second set of engaging members secured to one another by a second annular member. Each engaging member of the second set can include a first portion located on a first side of the second annular member. Each engaging member of the second set can include a second portion located on the second side of the second annular member. Each first portion can have a first drive surface oriented generally in the second rotational direction. Each first portion can have a first non-drive surface oriented generally in the first rotational direction. Each second portion can have a second drive surface oriented generally in the second rotational direction. Each second portion can have a second non-drive surface oriented generally in the first rotational direction.

[0015] In general, the first selector ring may be identical to the second selector ring.

[0016] The engagement members in the first set of engagement members may be evenly angularly distributed around the first annular member. 2 A set of engaging members may include 2 to 4 engaging members, preferably 3. In a set of 3 engaging members, the angle between adjacent engaging members may be about 120 degrees.

[0017] The engagement members in the second set of engagement members can be evenly angularly distributed around the second annular member. For example, the first set of engagement members can include two to four, preferably three, engagement members. In a set of three engagement members, the angle between adjacent engagement members can be approximately 120 degrees.

[0018] The first selector ring can include a first set of recesses formed through the first annular member, and each recess in the first set of recesses can be sized, shaped, and positioned to receive a respective one of the engagement members in the second set of engagement members. The first set of recesses facilitates relative translational movement between the first selector ring and the second selector ring.

[0019] The second selector ring may include a second set of recesses formed through the second annular member, each recess in the second set of recesses being a second 1 The second set of recesses may be sized, shaped, and positioned to receive a respective one of the engagement members in the set of engagement members. The second set of recesses facilitates relative translational movement between the first selector ring and the second selector ring.

[0020] The transmission system may include an actuator assembly arranged to control movement of the first and second selector rings.

[0021] The first selector assembly may be mounted on the shaft. The first gear element may be rotatably mounted on the shaft. The second gear element may be rotatably mounted on the shaft. The first selector assembly may be arranged to selectively lock the first and second gear elements for rotation with the first shaft. The shaft may include a first countershaft.

[0022] The first gear selector assembly can be arranged to selectively engage the first gear element in the following modes of operation: locking the first gear element for rotation with the shaft in both forward and reverse torque directions; locking the first gear element for rotation with the shaft in the forward torque direction but unlocking it in the reverse torque direction; and locking the first gear element for rotation with the shaft in the reverse torque direction but unlocking it in the forward torque direction.

[0023] With the first gear element engaged by the first and second sets of engaging members and locked for rotation in forward and reverse torque directions, one of the first and second sets of engaging members may be in a loaded state and the other of the first and second sets of engaging members may be in an unloaded state, and the actuator assembly may be arranged to selectively move the unloaded set of engaging members out of engagement with the first gear element, for example to a neutral position.

[0024] The first gear selector assembly can be arranged to selectively engage the second gear element in the following modes of operation: locking the second gear element for rotation with the shaft in both forward and reverse torque directions; locking the second gear element for rotation with the shaft in the forward torque direction but not in the reverse torque direction; and locking the second gear element for rotation with the shaft in the reverse torque direction but not in the forward torque direction.

[0025] With the second gear element engaged by the first and second sets of engaging members and locked for rotation in forward and reverse torque directions, one of the first and second sets of engaging members may be in a loaded state and the other of the first and second sets of engaging members may be in an unloaded state. The actuator assembly may be arranged to selectively move the unloaded set of engaging members out of engagement with the second gear element, for example to a neutral position.

[0026] The first selector assembly may be mounted to the shaft by a support sleeve, which may include internal splines arranged to lock the support sleeve for rotation with the shaft.

[0027] At least one, and preferably each, of the engagement members in the first set of engagement members can include a linear feature formed on an inwardly facing side thereof. The feature can be positioned to engage a complementary feature on the support sleeve. Typically, the feature comprises a channel and the complementary feature comprises a spline. This provides a rigid connection while allowing axial movement of the engagement member relative to the shaft.

[0028] At least one, and preferably each, of the engaging members in the second set of engaging members can include a linear feature formed on an inwardly facing side thereof and can be arranged to engage a complementary feature on the support sleeve. Typically, the feature comprises a channel and the complementary feature comprises a spline, which provides a rigid connection and allows axial movement of the engaging member relative to the shaft.

[0029] The first gear selector assembly may be arranged to provide torque support during gear shifting to ensure there is no loss of drive during gear shifting.

[0030] The transmission system may include a second gear selector assembly. The actuator assembly may be positioned to control operation of the second gear selector assembly.

[0031] The transmission system may include a third gear selector assembly. The actuator assembly may be positioned to control operation of the third gear selector assembly.

[0032] The actuator assembly can include a shift drum. The shift drum can include first and second portions. The second portion can be arranged to rotate relative to the first portion. The second portion can include a first control slot that can be arranged to control operation of the first selector assembly. The second portion can include a second control slot that can be arranged to control operation of the second gear selector assembly. The first portion can include a third control slot that can be arranged to control operation of the third gear selector assembly.

[0033] The actuator assembly can include a first shift fork assembly that can include a first shift fork arranged to control axial movement of the first selector ring and a second shift fork arranged to control axial movement of the second selector ring.

[0034] The actuator assembly can include a first shift collar mounted to the first shift rail. The first shift collar can include a first control member that engages with the first control slot. The shift drum can be positioned to adjust the position of the first control member along the first control slot by adjusting the rotational direction of the second portion of the shift drum, thereby adjusting the position of the first control member relative to the first shift rail. shift The axial position of the collar is controlled, thereby controlling the axial position of at least one of the first and second selector rings.

[0035] The second gear selector assembly can include a third selector ring. The actuator assembly can include a second shift fork assembly, the second shift fork assembly including a third shift fork positioned to control axial movement of the third selector ring.

[0036] The transmission system can include a first input shaft directly connected to the output of the drive source.The transmission system can include a second input shaft connected to the output of the drive source through a friction clutch.

[0037] A second gear selector assembly may be mounted on the second input shaft. A third gear element may be rotatably mounted on the second input shaft. A fourth gear element may be rotatably mounted on the second input shaft. The second gear selector assembly may be arranged to selectively lock each of the third and fourth gear elements for rotation with the second shaft.

[0038] The odd gears may be grouped together in a first portion of the transmission system, and the even gears may be grouped together in a second portion of the transmission system. The second gear selector assembly may be positioned to select between the odd gears and the even gears by selectively forming torque paths to the first and second portions of the transmission.

[0039] The third gear selector assembly can include a further selector ring. The actuator assembly can include a further shift fork assembly, the further shift fork assembly including a further shift fork arranged to control axial movement of the further selector ring.

[0040] The transmission system can include an output shaft. A third gear selector assembly can be mounted on one of the output shaft, the second countershaft, and a sleeve mounted on the second countershaft. At least one additional gear element can be rotatably mounted coaxially with the third gear selector assembly. The third gear selector assembly can be arranged to selectively lock the at least one additional gear element for rotation with the shaft on which it is mounted.

[0041] The third gear selector assembly may include a preselection selector assembly which may be arranged to preselect a new gear during a gear shift, for example before the first and second gear selector assemblies are operated.

[0042] In accordance with another aspect, a transmission system is provided.

[0043] The transmission may include a first gear selector assembly. The first gear selector assembly may include a first selector ring having a first set of engagement members. The first gear selector assembly may include a second selector ring having a second set of engagement members. The first and second selector rings may be capable of translational movement relative to one another.

[0044] The transmission may include a second gear selector assembly.

[0045] The transmission may include a third gear selector assembly.

[0046] The transmission can include an actuator assembly for controlling operation of the first, second, and third gear selector assemblies. The actuator assembly can include a shift drum having first and second portions. The second portion can be positioned to rotate relative to the first portion. The second portion can include a first control slot positioned to control operation of the first selector assembly. The second portion can include a second control slot positioned to control operation of the second gear selector assembly. The first portion can include a third control slot positioned to control operation of the third gear selector assembly.

[0047] The actuator assembly can include a first motor. The first motor can be positioned to rotate a first portion of the shift drum.

[0048] The actuator assembly can include a second motor. The second motor can be positioned to rotate the second portion of the shift drum. Thus, the first and second portions of the shift drum can rotate independently of one another.

[0049] The first portion of the shift drum may include a shaft having a flange (sometimes referred to as a shoulder) toward one end, and the third control slot may be formed in a curved surface of the flange.

[0050] The first portion of the shift drum can include a first sleeve mounted on the shaft. The first sleeve can be mounted on the shaft from the flange toward an opposite end of the shaft. The first sleeve can be fixed to rotate with the shaft.

[0051] At least one additional control slot may be formed in the curved surface of the first sleeve. Typically, the number of control slots in the first portion of the shift drum corresponds to the number of preselection gear assemblies, as described below.

[0052] The second portion of the shift drum can include a second sleeve rotatably mounted on the shaft. The first and second control slots can be formed in a curved surface of the second sleeve. Typically, the second sleeve can be disposed between the first sleeve and the flange. This configuration allows the first sleeve to assist in assembling the shift drum and, for example, allow the second sleeve to be rotatably mounted on the shaft.

[0053] The actuator assembly can include a first shift fork assembly. The first shift fork assembly can include a first shift fork arranged to control axial movement of the first selector ring. The actuator assembly can include a second shift fork arranged to control axial movement of the second selector ring.

[0054] The actuator assembly can include a first shift collar mounted to the first shift rail. The first shift collar can include a first control member that engages with the first control slot. The shift drum can be positioned to adjust the position of the first control member along the first control slot by adjusting the rotational direction of the second portion of the shift drum, thereby adjusting the position of the first control member relative to the first shift rail. shift Controls the axial position of the collar.

[0055] 1 on the 1st shift rail shift By adjusting the axial position of the collar, the axial position of at least one of the first shift fork-first selector ring pair and the second shift fork-second selector ring pair is adjusted relative to the first shift rail.

[0056] The first and second shift forks can be mounted to the second shift rail. An arm can protrude from the shift collar. The arm can be securely fastened to the second shift rail. The arm can be positioned to adjust the axial position of at least one of the first and second shift forks relative to the second shift rail.

[0057] The actuator assembly may include resilient means arranged to bias the first shift fork to a first axial position. The first axial position may represent a neutral operating condition. The actuator assembly may include resilient means arranged to bias the second shift fork to a second axial position. The second axial position may represent a neutral operating condition. The neutral operating condition is a condition in which the respective selector ring is not engaged with any of its associated gear elements.

[0058] The first gear selector assembly can be mounted on the first countershaft. The first gear element can be rotatably mounted on the first countershaft. The second gear element can be rotatably mounted on the first countershaft. The first gear selector assembly can be arranged to selectively lock the first and second gear elements for rotation with the first countershaft. The actuator assembly can be arranged to move the first selector ring into engagement with the first gear element to lock the first gear element for rotation with the first countershaft. The actuator assembly can be arranged to move the first selector ring into engagement with the second gear element to lock the second gear element for rotation with the first countershaft. The actuator assembly can be arranged to move the second selector ring into engagement with the first gear element to lock the first gear element for rotation with the first countershaft. The actuator assembly can be arranged to move the second selector ring into engagement with the first gear element to lock the first gear element for rotation with the first countershaft. The actuator assembly can be arranged to move the second selector ring into engagement with the second gear element to lock the second gear element for rotation with the first countershaft.

[0059] The first gear selector assembly can be arranged to lock the first gear element for rotation with the first countershaft in both the forward and reverse torque directions; to lock the first gear element for rotation with the first countershaft in the forward torque direction but not in the reverse torque direction; or to lock the first gear element for rotation with the first countershaft in the reverse torque direction but not in the forward torque direction.

[0060] The first gear selector assembly can be arranged to lock the second gear element for rotation with the first countershaft in both the forward and reverse torque directions; to lock the second gear element for rotation with the first countershaft in the forward torque direction but not in the reverse torque direction; or to lock the second gear element for rotation with the first countershaft in the reverse torque direction but not in the forward torque direction.

[0061] The first selector ring can be identical to the second selector ring, which was not the case with previous instantaneous selector assemblies. Using identical selector rings reduces the manufacturing costs of the transmission system.

[0062] Each engagement member in the first set of engagement members has a first end and a second end. The first end can include a first drive surface and a first non-drive surface. The second end can include a second drive surface and a second non-drive surface. The first and second drive surfaces are oriented to face the same rotational direction. This differs from conventional momentary selector assemblies, in which the drive surfaces of any engagement members face opposite rotational directions, resulting in incompatible selector rings and requiring separate gear selector rings. By orienting the drive surfaces of each engagement member of the selector ring in the same rotational direction, a pair of identical selector rings can be used.

[0063] Each engagement member in the second set of engagement members has a first end and a second end. The first end can include a first drive surface and a first non-drive surface. The second end can include a second drive surface and a second non-drive surface. The first and second drive surfaces are oriented to face the same rotational direction. This differs from conventional momentary selector assemblies, in which the non-drive surfaces of any engagement members face opposite rotational directions, resulting in incompatible selector rings and requiring separate gear selector rings. By orienting the non-drive surfaces of each engagement member of the selector ring in the same rotational direction, a pair of identical selector rings can be used.

[0064] The first selector ring can include a first annular member connecting the first set of engagement members to one another. The first annular member can be recessed to allow the second set of engagement members to pass through the first annular member. This facilitates relative translational movement between the selector rings and allows the annular member to have a relatively large depth, which helps improve the durability of the selector ring.

[0065] The second selector ring may include a second annular member connecting the second set of engaging members to each other. 2 A recess may be formed in the second annular member to allow the annular member to pass through, which facilitates relative translational movement between the selector rings and allows the annular member to have a relatively large depth, which helps improve the durability of the selector ring.

[0066] The first gear selector assembly may be arranged to provide torque support during gear shifting to ensure there is no loss of drive during gear shifting.

[0067] The second gear selector assembly can include a third selector ring. The actuator assembly can include a second shift fork assembly, the second shift fork assembly including a third shift fork positioned to control axial movement of the third selector ring.

[0068] The actuator assembly can include a second shift collar mounted on the further shift rail. The second shift collar can include a second control member that engages with the second control slot, and the shift drum can be arranged to adjust the position of the second control member along the second control slot by adjusting the rotational direction of the second portion of the shift drum, thereby adjusting the position of the second control member relative to the further shift rail. shift Controls the axial position of the collar.

[0069] 2nd on further shift rail shift By adjusting the axial position of the collar, the axial position of the third shift fork and third selector ring can be adjusted relative to the further shift rail.

[0070] The transmission system includes a first input shaft directly connected to the output of the drive source. The transmission system includes a second input shaft connected to the output of the drive source through a friction clutch. A second gear selector assembly can be mounted on the second input shaft. A third gear element can be rotatably mounted on the second input shaft. A fourth gear element can be rotatably mounted on the second input shaft. The second gear selector assembly can be arranged to selectively lock each of the third and fourth gear elements for rotation with the second shaft. "Direct" means that there is no friction clutch in the drive line between the drive source and the first input shaft. The drive source can be any suitable source, such as a combustion engine or an electric motor. An actuator assembly can be arranged to move a third selector ring into engagement with the third gear element to lock the third gear element for rotation with the second input shaft. The actuator assembly can be arranged to move a third selector ring into engagement with the fourth gear element to lock the fourth gear element for rotation with the second input shaft.

[0071] The odd gears (e.g., first, third, and fifth gears) can be grouped together in a first portion of the transmission. The even gears (e.g., second, fourth, and sixth gears) can be grouped together in a second portion of the transmission. The second gear selector assembly can be positioned to select between the odd and even gears by selectively forming torque paths to the first and second portions of the transmission. For example, the odd gears can be drivingly connected to a second countershaft. The even gears can be drivingly connected to a sleeve rotatably mounted on the second countershaft. The second gear selector assembly can be positioned to selectively form a first torque path to the second countershaft. The second gear selector assembly can be positioned to selectively form a second torque path to a sleeve mounted on the second countershaft. The odd side of the transmission can include first, third, and fifth gears. The odd side of the transmission can include additional odd gears, such as seventh and ninth gears. The even side of the transmission system can include even gears such as 2nd gear, 4th gear, and 6th gear. The even side of the transmission system can include additional even gears such as 8th gear and 10th gear.

[0072] The third gear selector assembly may include a further selector ring and the actuator assembly may include a further shift fork assembly, the further shift fork assembly may include a further shift fork arranged to control axial movement of the further selector ring.

[0073] The actuator assembly may include a further shift collar mounted on the further shift rail. The further shift collar may include a further control member that engages with the third control slot. The shift drum may be arranged to adjust the position of the further control member along the third control slot by adjusting the rotational direction of the first portion of the shift drum, thereby adjusting the position of the further control member relative to the further shift rail. shift Controls the axial position of the collar.

[0074] Further on the additional shift rail shift By adjusting the axial position of the collar, the axial position of the additional shift forks and the additional selector ring can be adjusted relative to the additional shift rail.

[0075] The transmission system may include an output shaft. The third gear selector assembly may be mounted on one of the output shaft, the second countershaft, and a sleeve mounted on the second countershaft. At least one additional gear element may be rotatably mounted coaxially with the third gear selector assembly. The third gear selector assembly may be arranged to selectively lock the at least one additional gear element for rotation with the shaft on which it is mounted. In some embodiments, the third gear selector assembly is arranged to selectively lock the fifth and sixth gear elements to the shaft on which it is mounted.

[0076] The third gear selector assembly may comprise a preselection selector assembly arranged to preselect a new gear before a gear shift occurs. In practice, this typically means that a new gear is preselected by the third gear selector assembly before the first gear selector assembly and / or the second gear selector assembly change their operating state during a gear shift, for example before selecting a new gear element or moving to a neutral position.

[0077] The third gear selector assembly may include a further selector ring movable into and out of engagement with the further gear elements, which may be movable into and out of engagement with the fifth and sixth gear elements.

[0078] The further selector ring may comprise a gear element arranged to slide axially along the shaft on which it is mounted.

[0079] The transmission system may include at least one additional gear selector assembly, the additional gear selector assembly including a preselection selector assembly configured to preselect a new gear before a gear shift occurs, the additional gear selector assembly including an additional selector ring, the actuator assembly including an additional shift fork assembly, the additional shift fork assembly including an additional shift fork arranged to control axial movement of the additional selector ring, the actuator assembly including an additional shift collar mounted on the additional shift rail, the additional shift collar including an additional control member that engages with a fourth control slot formed in the first portion of the shift drum, the shift drum arranged to adjust a position of the additional control member along the fourth control slot by adjusting a rotational direction of the first portion of the shift drum, thereby controlling the axial position of the additional collar relative to the additional shift rail, shift Adjusting the axial position of the collar adjusts the axial position of the additional shift fork and additional selector ring relative to the additional shift rail.

[0080] According to another aspect, there is provided a drive train including a drive source, a friction clutch device, and a transmission system according to any of the configurations described herein. The friction clutch device can be a wet friction clutch or a dry friction clutch.

[0081] The present invention has many advantages, including the following: The shifting system is much less complex and easier to control than a DCT type shifting system, and less complex and easier to control than an instantaneous shifting system. Due to the layout of the transmission, the amount of inertia that must be synchronized is relatively small, so the synchronizer capacity is small. In a DCT, the synchronizer capacity is significantly larger. Only one type of synchronizer is required, which reduces manufacturing costs. DCTs often require many different types of synchronizers for different parts of the transmission. The transmission layout and shift strategy employed allows torque support during at least some gear shifts. The transmission layout is very compact and versatile in the sense that it can be used in front-wheel drive, rear-wheel drive and all-wheel drive vehicles. The layout uses many regular transmission parts, so existing manufacturing lines can be easily adapted to manufacture this transmission layout. The layout and shift strategy allows the transmission torque to be controlled during gear shifts to eliminate engagement torque spikes, eliminating the need for dampers on any gear.

[0082] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which like reference numerals indicate equivalent features and in which: [Brief explanation of the drawings]

[0083] [Figure 1] 1 is a schematic diagram of a discrete ratio transmission system suitable for use in a vehicle in accordance with an embodiment of the present invention; [Figure 2] FIG. 2 is a schematic isometric front view of two gear selector assemblies, associated gear elements shown, and an actuator assembly arranged to operate the gear selector assemblies used in the transmission of FIG. 1; [Figure 3] FIG. 3 is a schematic rear isometric view of the gear selector assembly of FIG. 2, with associated gear elements shown, and the actuator assembly. [Figure 4] FIG. 3 is a schematic front view of the gear selector assembly of FIG. 2, with associated gear elements shown, and an actuator assembly. [Figure 5] FIG. 3 is a schematic side view of the gear selector assembly of FIG. 2, with associated gear elements shown, and an actuator assembly. [Figure 6] 3 is a schematic cross-sectional view of the gear selector assembly of FIG. 2, with associated gear elements shown, and an actuator assembly. [Figure 7] FIG. 7 is a schematic enlarged view of a portion of FIG. [Figure 8a] FIG. 3 is an isometric view of first and second gear selector rings from the first gear selector assembly shown in FIG. [Figure 8b] FIG. 8b is an enlarged isometric view of an engagement element from the first gear selector ring of FIG. 8a. [Figure 8c] FIG. 8b is an enlarged isometric view of an engagement element from the second gear selector ring of FIG. 8a. [Figure 9] 9 is a side view of the pair of selector rings shown in FIG. 8 mounted on the hub and connected to the actuator fork.

[0084] FIG. 1 illustrates a drive train including a transmission system 300 according to the present invention, a friction clutch 386, such as a dry friction clutch, and a drive source 380, such as a combustion engine or electric motor. The transmission system is a multi-speed transmission 300. FIG. 1 illustrates a six-speed transmission with odd and even gears grouped together. Those skilled in the art will appreciate that the transmission layout can be expanded to any number of gears by adding / subtracting gear trains on the odd and / or even sides. The illustrated transmission 300 is particularly suited for vehicles such as motorcycles.

[0085] The transmission system can be arranged as a fully automatic, semi-automatic, or fully manual transmission.

[0086] The transmission system 300 has a first input shaft 301 directly connected to the output of the drive source 380 and a second input shaft 303 connected to the output of the drive source 380 via a clutch 386 .

[0087] The first input shaft 301 is tubular and is arranged to coaxially accommodate a portion of the second input shaft 303 .

[0088] The gear shifting system is No. 1The first input shaft 301 includes a countershaft 305. Drive is transferred from the first input shaft 301 to the first countershaft 305 by a gear train comprising a pair of gear elements 302, 304. Gear element 302 is fixed for rotation with the first input shaft. Gear element 304 is fixed for rotation with the first countershaft 305. Gear element 302 meshes with gear element 304.

[0089] The two gear elements 306, 308 are rotatably mounted by bearings on the first countershaft 305. Each gear element 306, 308 is selectively locked for rotation with the first countershaft 305 by a first gear selector assembly 329.

[0090] Gear element 306 meshes with gear element 312, which is rotatably mounted on second input shaft 303 by a bearing. Gear element 308 meshes with gear element 314, which is rotatably mounted on second input shaft 303 by a bearing. Gear elements 312, 314 are selectively locked for rotation with second input shaft 303 by second gear selector assembly 331. Second selector assembly 331 is a conventional gear selector assembly, such as a synchromesh selector assembly or a standard selector ring. Gear elements 312, 314 each include appropriate engagement mechanisms and / or synchronization devices.

[0091] Transmission system 300 further includes a countershaft 307 and an output shaft 309. Gear element 312 meshes with gear element 316 that is fixed for rotation with countershaft 307. Gear element 314 meshes with gear element 318 that is rotatably mounted on countershaft 307 via a sleeve 330 and a bearing.

[0092] The first through sixth gears are arranged to transfer torque between the countershaft 307 and the output shaft 309. The odd gears are grouped together on a first side of the transmission and the even gears are grouped together on a second side of the transmission. Looking from right to left in FIG. 1, the gears are arranged as follows: 2nd, 6th, 4th, 3rd, 5th, and 1st.

[0093] The second gear includes a gear element 332 fixed to rotate with sleeve 330 and a gear element 334 rotatably mounted on output shaft 309 via a bearing. The sixth gear includes a gear element 336 rotatably mounted on sleeve 330 via a bearing and a gear element 338 fixed to rotate with output shaft 309 and arranged to slide axially along output shaft 309. The fourth gear includes a gear element 340 fixed to rotate with sleeve 330 and arranged to slide axially along sleeve 330 and a gear element 342 rotatably mounted on output shaft 309 via a bearing.

[0094] Gear element 338 functions as a first preselection device and is arranged to slide into and out of engagement with gear elements 342, 334 to selectively lock gear elements 342 and 334 for rotation with output shaft 309, thereby preselecting fourth gear and second gear, respectively.

[0095] Gear element 340 functions as a second preselection assembly and is positioned to selectively lock gear element 336 for rotation with sleeve 330, thereby preselecting sixth gear.

[0096] The third gear includes a gear element 344 fixed for rotation with the countershaft 307 and a gear element 346 rotatably mounted on the output shaft 309 via a bearing. Gear element 344 is arranged to slide axially along the countershaft 307. The fifth gear includes a gear element 348 rotatably mounted on the countershaft 307 via a bearing and a gear element 350 fixed for rotation with the output shaft 309. Gear element 350 is arranged to slide axially along the output shaft 309. The first gear includes a gear element 352 fixed for rotation with the countershaft 307 and a gear element 354 rotatably mounted on the output shaft 354 via a bearing.

[0097] Gear element 344 functions as a preselection assembly, sliding axially into and out of engagement with gear element 348 to selectively lock gear element 348 for rotation with countershaft 307, thereby preselecting fifth gear. Gear element 350 functions as a preselection assembly, selectively locking gear elements 346, 354 for rotation with output shaft 309, thereby preselecting third and first gears, respectively.

[0098] The preselection assemblies 340, 344, 350, 358 are arranged like a conventional synchromesh selector or dog clutch arrangement. The gears selected by the preselection assemblies 340, 344, 350, 358 include appropriate drive mechanisms that can be engaged by the preselection assemblies 340, 344, 350, 358.

[0099] When second selector assembly 331 is engaged with gear element 312, a torque path is provided between second input shaft 303, countershaft 307, and the odd side of the transmission (i.e., at least one of first gear, third gear, and fifth gear). When second selector assembly 331 is engaged with gear element 314, a torque path is provided between second input shaft 303, sleeve 330, and the even side of the transmission (i.e., at least one of second gear, fourth gear, and sixth gear). Thus, second selector assembly 331 is positioned to select between odd and even gears.

[0100] The first selector assembly 329 is configured to engage a first set of drive mechanisms 320 disposed on gear element 306 and a second set of drive mechanisms 320 disposed on gear element 308 (see FIG. 1). The drive mechanisms 320 of each gear element 306, 308 each include a group of dogs disposed on a respective side of the gear element 306, 308. Typically, there are three dogs in each group 320. The dogs within a group are evenly distributed circumferentially around countershaft 305, i.e., the angle between the centers of a pair of dogs is approximately 120 degrees. The use of three dogs is preferred because this arrangement provides a relatively large engagement window, i.e., space between the dogs, for receiving an engagement member from the first selector assembly 329. Three dogs also provide inherent self-centering and even load distribution. The large engagement window increases the chance that the first selector assembly 329 will fully engage the gear elements 306, 308.

[0101] A first selector assembly 329 is mounted on the countershaft 305 between the drive mechanism 320 mounted on the gear elements 306, 308 (see Figures 1 and 4).

[0102] First gear selector assembly 329 includes first and second sets of engagement members 45, 46 (see Figures 8 and 9). First set of engagement members 45 includes three members 45a-45c evenly distributed around countershaft 305. Second set of engagement members 46 includes three members 46a-46c evenly distributed around countershaft 305.

[0103] The first and second sets of engagement members 45, 46 are mounted on a support 49 that is fixed for rotation with the countershaft 305 (see Figures 7 and 9). The sets of engagement members 45, 46 are arranged to rotate with the countershaft 305, but can slide axially along the support 49, and therefore along the countershaft 305, in response to switching movements of the actuator assembly 400. To facilitate this, the support 49 includes six hooks 51 formed in its curved surface, each of which is arranged to engage a channel 52 formed in its respective engagement member 45a-45c, 46a-46c.

[0104] The support 49 includes internal splines 49a arranged to engage external splines formed on the countershaft 305. This provides a very strong connection between the support 49 and the countershaft 305. The spline arrangement locks the support 49, and therefore the first and second sets of engaging members 45, 46, for rotation with the countershaft 305.

[0105] The sets of engaging members 45, 46 are arranged such that the members 45a-45c, 46a-46c of each set are alternately positioned on the hooked portions 51, allowing the member sets 45, 46 to slide along the support 49. The first set of engaging members 45a-45c are rigidly connected to each other by a first annular connector member 53 and move as a unit. Thus, the first set of engaging members 45a-45c and the first annular connector member 53 together form a first gear selector ring 54. The first set of engaging members 45a-45c are evenly distributed around the first annular connector member 53. The second set of engaging members 46a-46c are rigidly connected to each other by a second annular connector member 55 and move as a unit. Thus, the second set of engaging members 46a-46c and the second annular connector member 55 together form a second gear selector ring 56. The second set of engaging members 46a-46c are evenly distributed around the second annular connector member 55. Each set of engaging members 45, 46 is capable of translational movement relative to each other. When there is relative movement between the first and second sets of engaging members 45, 46, the first annular connector member 53 moves on the second set of engaging members 46 and the second annular connector member 55 moves on the first set of engaging members 45.

[0106] The annular connecting members 53, 55 are formed with recesses 60, 62, respectively. The recesses 60 are sized, shaped, and positioned to receive the respective second engaging members 46. The recesses 62 are sized, shaped, and positioned to receive the respective first engaging members 45. Thus, the number of recesses 60, 62 corresponds to the number of received engaging members 45, 46. The recesses 60, 62 facilitate relative movement of the pairs of engaging members 45, 46.

[0107] The annular connector member 53 can be positioned relative to its engaging members 45 such that the length of the portion of each engaging member on a first side of the connector member 53 is greater than the length of the portion of each engaging member on a second side of the connector member. circular Connector parts 55 Each connecting member 53, 55 may be positioned relative to its engaging member 46 such that the length of the portion of each engaging member on the first side of the connecting member is longer than the length of the portion of each engaging member on the second side of the connecting member. For example, the portion of the engaging member on the first side of each connecting member 53, 55 may be approximately three to four times the length of the portion of the engaging member on the second side of each connecting member 53, 55.

[0108] Each of the first set of engagement members 45a-45c has a first end 59 positioned to engage a first group of dogs 320 attached to the gear element 306 and a second end 61 positioned to engage a second group of dogs 320 attached to the gear element 308. The first end 59 of each of the first engagement members 45a-45c is positioned to selectively engage the first group of dogs 320 during deceleration (reverse torque direction) of the gear element 306, and the second end 61 is positioned to selectively engage the second group of dogs 320 during deceleration (reverse torque direction) of the gear element 308. For each of the second set of engagement members 46a-46c, the first end 63 is positioned to engage the second group of dogs 320 during acceleration (positive torque direction) of the gear element 308, and the second end 65 is positioned to engage the first group of dogs 320 during acceleration (positive torque direction) of the gear element 306.

[0109] This arrangement allows the first and second selector rings to be identically positioned relative to one another, as opposed to conventional momentary selector assemblies in which the selector rings are positioned in opposite directions relative to one another. This arrangement reduces manufacturing costs for the first selector assembly 329 by requiring only one type of selector ring 54, 56.

[0110] When both the first and second sets of engagement members 45, 46 are engaged with one of the first and second sets of dogs 320, drive is transmitted between the respective gear elements 306, 308 and the first gear selector assembly 329 in both the forward and reverse torque directions.

[0111] Each of the first and second ends 59, 61, 63, 65 of the engagement members includes a drive surface 67 for drivingly engaging the respective dog 320, a non-drive surface in the form of a ramp 69, and an end surface 71 (see FIG. 8). The end surface 71 limits axial movement of the engagement members 45a-45c, 46a-46c. In some arrangements, the sides of the dog 320 may be ramped. In this case, the drive surface 67 may be angled to complement the sides of the dog 320 to provide face-to-face contact to reduce wear as the engagement members 45a-45c, 46a-46c rotate into engagement. The purpose of the non-drive surface 69 is to prevent locking engagement between the engagement member and the dog 320. Each non-drive surface 69 is preferably helically shaped and ramped away from the respective end surface 71. Non-Drive Surface 69 The angle of inclination of the non-drive surface 69 can be such that the longitudinal distance between the edge of the non-drive surface farthest from end face 71 and the plane of end face 71 is greater than the height of dog 320. This can prevent the transmission from locking up if there is relative rotational movement between engagement members 45a-45c, 46a-46c and dog 320 such that non-drive surface 69 moves toward its respective dog 320. Dog 320 does not strike the side of engagement member 45a-45c, 46a-46c, but rather engages non-drive surface 69. Further relative rotational movement between dog 320 and engagement member 45a-45c, 46a-46c causes dog 320 to slide across non-drive surface 69, and the inclined surface of the non-drive surface causes engagement member 45a-45c, 46a-46c to move axially along countershaft 305 away from its respective dog 320 to prevent the transmission from locking up. Thus, the non-drive surface 69 provides a ratchet effect such that the first gear selector assembly 329 is arranged to slip relative to the gear elements 306, 308, respectively, under certain operating conditions.

[0112] In this manner, first selector assembly 329 is arranged to selectively engage gear element 306 in the following modes of operation: locking gear element 306 for rotation with shaft 305 in the forward and reverse torque directions, locking gear element 306 for rotation with shaft 305 in the forward torque direction but not in the reverse torque direction, and locking gear element 306 for rotation with shaft 305 in the reverse torque direction but not in the forward torque direction.

[0113] When the gear element 306 is locked for rotation in the forward and reverse torque directions (engaged by the first and second sets of engaging members 45, 46), one of the first and second sets of engaging members 45, 46 is in a loaded state and the other of the first and second sets of engaging members 45, 46 is in an unloaded state. The actuator assembly 400 is arranged to selectively move the unloaded set of engaging members 45, 46 out of engagement with the currently engaged gear element 308, for example to a neutral position.

[0114] First selector assembly 329 is arranged to selectively engage gear element 308 in the following modes of operation: locking gear element 308 for rotation with shaft 305 in the forward and reverse torque directions, locking gear element 308 for rotation with shaft 305 in the forward torque direction but not in the reverse torque direction, and locking gear element 308 for rotation with shaft 305 in the reverse torque direction but not in the forward torque direction.

[0115] When the gear element 308 is locked for rotation in the forward and reverse torque directions (engaged by the first and second sets of engaging members 45, 46), one of the first and second sets of engaging members 45, 46 is in a loaded state and the other of the first and second sets of engaging members 45, 46 is in an unloaded state. The actuator assembly 400 is arranged to selectively move the unloaded set of engaging members 45, 46 from engagement with the currently engaged gear element 306 to, for example, a neutral position. The first selector assembly 329 can be in a neutral (disengaged) state with respect to the gear elements 306, 308.

[0116] When the first and second sets of members 45, 46 are fully engaged with the gear element 306, the dog 320 is located between each pair of drive faces 67 on the first end 59 of the first set of members 45 and the second end 65 of the second set of members 46. When the first and second sets of members 45, 46 are fully engaged with the gear element 308, the dog 320 is located between the drive faces 67 on the second end 63 of the first set of members 45 and adjacent to the drive faces 67 on the first end 61 of the second set of members 46. The dimensions of the dog 320 and the ends 59, 61, 63, 65 of the engagement members ensure that there is little movement of each dog between the drive faces 67 of the acceleration members and the drive faces 67 of the deceleration members as the gear elements 306, 308 move from acceleration to deceleration or vice versa, resulting in little or no backlash in the gears. Backlash is the lost motion experienced when the dog moves from the drive surface 67 of the acceleration member to the drive surface 67 of the deceleration member, or vice versa, when moving from acceleration to deceleration. The backlash in a conventional dog-type transmission is approximately 30 degrees. The backlash in a typical automotive transmission according to this embodiment is less than 5 degrees.

[0117] The transmission system includes a first selector assembly 329, a second selector assembly 331, and an actuator assembly 400 arranged to control operation of at least one pre-selection assembly 340, 344, 350, 358, typically a plurality of pre-selection assemblies 340, 344, 350, 358. In some arrangements, the actuator assembly 400 is arranged to control operation of each of the pre-selection assemblies 340, 344, 350, 358.

[0118] The actuator assembly 400 includes a shift drum 401. The shift drum 401 has a first portion 403 and a second portion 405. The first portion includes a shaft 407 having a flange 407a located at a first end 411 of the shaft. A sleeve 413 is mounted on the shaft 407 toward a second end 415 of the first portion 407. The sleeve 413 is fixed for rotation with the shaft 407, for example, by a spline arrangement. The first portion 403 has a plurality of control slots 409 formed therein. For example, the control slot 409a can be formed in an outer curved surface of the flange 407a. The outer curved surface of the sleeve 413 can have a plurality of control slots 409b-409c formed therein. Typically, the number of control slots 409 formed in the outer curved surface corresponds to the number of pre-selector assemblies 340, 344, 350, 358 (for illustrative purposes, only three control slots 409a-409c are shown in the figures). The second part comprises a sleeve 417 rotatably mounted by bearings on the shaft 407. The outer curved surface of the sleeve 417 has a plurality of control slots 419, 421 formed therein.

[0119] The actuator assembly 400 includes a drive system arranged to selectively rotate the first portion 403 of the shift drum and the second portion 405 of the shift drum, such that the second portion 405 of the shift drum is rotated independently of the first portion 403 of the shift drum. The first portion 403 includes a gear element 423 fixed to rotate with the shaft 407 and the sleeve 413. The second portion 405 includes a gear element 425 fixed to rotate with the sleeve 417. The drive system includes a first electric motor 427 and a first worm gear 429. The first worm gear is in meshing engagement with the gear element 423. The first electric motor is arranged to selectively rotate the first portion 403 (the shaft 407 and the sleeve 413) by driving the first worm gear 429, which in turn rotates the gear element 423. The drive system includes a second electric motor 431 and a second worm gear 433. The second worm gear 433 is in meshing engagement with the gear element 425. The second electric motor is positioned to selectively rotate the second portion 405 (sleeve 417) by driving the second worm gear 433, which in turn rotates the gear element 425. A control system and / or switching device (not shown) may be used to control the operation of the first and second electric motors 427, 431.

[0120] Actuator Assembly 400 is a first shift fork assembly arranged to control the operation of first selector assembly 329. 434 First shift fork assembly 434 includes a shift rail 435, a shift rail 437, a shift collar 439, a first shift fork 441, and a second shift fork 443.

[0121] The shift collar 439 includes a sleeve 445 mounted on the shift rail 435 and arranged to slide axially along the shift rail 435. The shift collar 439 includes a control member 447 protruding radially outward from the sleeve 445. One end of the control member 447 is located within a control slot 419 formed in the sleeve 417. When the sleeve 417 rotates, the control member 447 moves along the control slot 419, and the serpentine shape of the control slot 419 adjusts the axial position of the shift collar 439 relative to the shift rail 435. The shift collar 439 includes an arm 449 protruding radially outward from the sleeve 445 in a direction generally opposite to the direction in which the control member 447 protrudes. The arm 449 has a through hole, and the shift rail 437 passes through the through hole. The arm 449 is fixed to the shift rail 437; for example, the arm can be pinned to the shift rail 437. When the axial position of sleeve 445 is adjusted relative to shift rail 435, the axial position of shift rail 437 is similarly adjusted.

[0122] The first shift fork 441 is positioned to control the operation of the first set of engaging members 45. The first shift fork 441 includes a sleeve 441a and a bifurcated member 441b. The sleeve 441a is mounted on the shift rail 437 between a first stop 451a and an arm 449. A helical spring 453 is mounted between the first stop 451a and the sleeve 441a, and a helical spring 455 is located between the sleeve 441a and the arm 449. The bifurcated member 441b engages with the first annular connector member 53 and is positioned to adjust the axial position of the first set of engaging members 45 relative to the first countershaft 305, thereby selectively moving the first set of engaging members 45 into and out of engagement with dogs 320 on the gear elements 306, 308 mounted on the first countershaft 305. The helical springs 453, 455 are positioned to bias the first shift fork 441 to a neutral position, i.e., a position in which the first set of engagement members 45 are not engaged with either of its gear elements 306, 308. The helical springs 453, 455 also damp movement of the first shift fork 441.

[0123] The second shift fork 443 is a second set of engagement members 46 The second shift fork 443 includes a sleeve 443a and a bifurcated member 443b. The sleeve 443a is mounted on the shift rail 437 between the second stop 451b and the arm 449. A helical spring 457 is mounted between the second stop 451b and the sleeve 443a, and the helical spring 459 is located between the sleeve 443a and the arm 449. The bifurcated member 443b engages the second annular connector member 55 and is positioned to adjust the axial position of the second set of engaging members 46 relative to the first countershaft 305, thereby selectively moving the second set of engaging members 46 into and out of engagement with dogs 320 on the gear elements 306, 308 mounted on the first countershaft 305. The helical springs 457, 459 are positioned to bias the second shift fork 443 to a neutral position, i.e., a position in which the second set of engagement members 46 are not engaged with either of its gear elements 306, 308. The helical springs 457, 459 also damp movement of the second shift fork 443.

[0124] The selector assembly 400 includes a second shift fork assembly 461 arranged to control the operation of the second selector assembly 331. The second shift fork assembly 461 includes a shift rail 463, a shift collar 465, and a third shift fork 467.

[0125] The shift collar 465 is mounted to the shift rail 463 and includes a sleeve 469 arranged to slide axially along the shift rail 463. The shift collar 465 includes a control member 471 that projects radially outward from the sleeve 469. One end of the control member 471 is located within a control slot 421 formed in the sleeve 417. As the sleeve 417 rotates, the control member 471 moves along the control slot 421, and the serpentine shape of the control slot 421 adjusts the axial position of the shift collar 465 relative to the shift rail 463. A third shift fork 467 projects radially outward from the sleeve 469 in a direction generally opposite to the direction in which the control member 471 projects.

[0126] The third shift fork 467 is positioned to control the operation of a conventional selector ring 473 that is part of the second selector assembly 331. Axial movement of the sleeve 469 along the shift rail 463 adjusts the axial position of the selector ring 473 relative to the second input shaft 303, selectively engaging and locking the gear elements 312, 314 for rotation therewith. With the selector ring 473 engaged with the gear element 312, a torque path is established between the second input shaft 303 and the odd gears (first, third, and fifth), with the actual gear selected being determined by the positions of the pre-selection assemblies 344, 350. With the selector ring 473 engaged with the gear element 314, a torque path is established between the second input shaft 303 and the even gears (second, fourth, and sixth), with the actual gear selected being determined by the positions of the pre-selection assemblies 338, 340.

[0127] It is therefore apparent that the direction of rotation of the second portion 405 of the shift drum determines the operative positions of the first, second and third shift forks 441, 443, 467 and thus the operative states of the first and second selector assemblies 329, 331.

[0128] A plurality of shift forks (not shown) operatively connected to respective ones of the control slots 409a-409c in the first portion 403 of the shift drum are arranged to adjust the axial positions of the pre-selection assemblies 338, 340, 344, 350. Thus, the direction of rotation of the first portion 403 of the shift drum determines the operative positions of the plurality of shift forks, and thus the operative position of at least some, and preferably each, of the pre-selection assemblies 338, 340, 344, 350. Thus, in some embodiments, only a single shift drum 401 is required for the entire transmission.

[0129] The transmission provides torque support during power-on upshifts, power-on downshifts, power-off shifts, and power-off downshifts. Therefore, there is no loss of drive to the output shaft during gear shifts. The transmission thus provides seamless shifting for all major shift types by preselecting the appropriate gear and then controlling torque using the first and second selector devices 329, 331. By synchronizing the drive source and / or clutch speed with the new gear before the shift occurs, a substantially shock-free engagement can be achieved.

[0130] Some example shift sequences and relative positions of the selector assemblies are shown in the table below. In the table below, for the first selector assembly 329, "N" indicates neutral, "E" indicates that gear element 308 is engaged, and "O" indicates that gear element 306 is engaged. For the second selector assembly 331, "E" indicates that gear element 314 is engaged and "O" indicates that gear element 312 is engaged. Control slots 409a-409c in the first shift drum portion 403 and control slots 419, 421 in the second shift drum portion 405 are positioned to operate the respective selector assemblies accordingly. [Table 1] [Table 2] [Table 3] [Table 4]

[0131] Those skilled in the art will appreciate that modifications can be made to the above embodiments that fall within the scope of the present invention, for example, the transmission can include a different number of gears, such as a 7-speed, 8-speed, 9-speed or 10-speed transmission.

[0132] The number of control slots 409 formed in the first portion 403 of the shift drum may vary. The number of control slots 409 formed in the first portion 403 of the shift drum may vary from the number of pre-selector assemblies. If more pre-select gear selector assemblies are required, additional shift drums may be required.

[0133] The description presents exemplary embodiments and, together with the drawings, serves to explain the principles of the present invention. However, the scope of the present invention is not intended to be limited to the exact details of the embodiments, as variations will be apparent to those skilled in the art and are deemed to be encompassed by the claims. The terms for components used in this specification should be given a broad interpretation to encompass equivalent functions and features. In some cases, alternative terms (synonyms) are provided for structural features, but such terms are not intended to be exhaustive.

[0134] Descriptive terms should also be interpreted as broadly as possible: for example, the term "comprising" as used herein means "including," so that each statement herein containing the term "comprising" may be interpreted to mean "including," such that features other than that term or the term preceded by that term may also be present. Related terms such as "comprise" and "comprises" should be interpreted similarly. Terms indicating directions, such as "vertical," "horizontal," "up," "down," "upper," and "lower," may be used for convenience of description, usually with reference to the figures, and are not intended to be ultimately limiting, where equivalent functionality can be achieved with alternative dimensions and / or orientations.

[0135] Although reference is made herein to embodiments having specific combinations of constituent steps or features, it is contemplated that additional combinations and intercombinations of steps or features that are compatible between embodiments are possible. Indeed, separated features may function as inventions independently of other features and need not necessarily be implemented as a complete combination. Any feature of an embodiment may be separated from that embodiment and included in any other embodiment.

Claims

1. 1. A transmission system including a first gear selector assembly, the first gear selector assembly including a first selector ring and a second selector ring, the first and second selector rings being translatable relative to one another, the first selector ring including a first set of engaging members secured to one another by a first annular member, each engaging member of the first set including a first portion located on a first side of the first annular member and a second portion located on a second side of the first annular member, each first portion having a first drive surface oriented generally in a first rotational direction and a first non-drive surface oriented generally in a second rotational direction, and each second portion having a first drive surface oriented generally in a second rotational direction. a second drive surface oriented generally in the second rotational direction and a second non-drive surface oriented generally in the second rotational direction, the second selector ring including a second set of engaging members secured to one another by a second annular member, each engaging member of the second set including a first portion located on a first side of the second annular member and a second portion located on a second side of the second annular member, each first portion having a first drive surface oriented generally in the second rotational direction and a first non-drive surface oriented generally in the first rotational direction, and each second portion including a second drive surface oriented generally in the second rotational direction and a second non-drive surface oriented generally in the first rotational direction.

2. 2. The transmission system of claim 1, wherein said first selector ring is identical to said second selector ring.

3. The transmission system of claim 1 , wherein said engaging members in said first set of engaging members are evenly angularly distributed around said first annular member.

4. The transmission system of claim 1 , wherein said engaging members in said second set of engaging members are evenly angularly distributed around said second annular member.

5. 2. The transmission system of claim 1, wherein said first selector ring includes a first set of recesses formed through said first annular member, each recess in said first set of recesses sized, shaped and positioned to receive a respective one of said engaging members in said second set of engaging members.

6. 2. The transmission system of claim 1, wherein said second selector ring includes a second set of recesses formed through said second annular member, each recess in said second set of recesses sized, shaped and positioned to receive a respective one of said engaging members in said first set of engaging members.

7. 2. The transmission system of claim 1 including an actuator assembly positioned to control movement of said first and second selector rings.

8. 2. The transmission system of claim 1, wherein said first selector assembly is mounted on a shaft, a first gear element is rotatably mounted on said shaft, and a second gear element is rotatably mounted on said shaft, said first selector assembly being arranged to selectively lock said first and second gear elements for rotation with said first shaft.

9. The transmission system of claim 8 wherein said shaft comprises a first countershaft.

10. 9. The transmission system of claim 8, wherein said first gear selector assembly is arranged to selectively engage said first gear element in the following modes of operation: locking said first gear element for rotation with said shaft in both forward and reverse torque directions; locking said first gear element for rotation with said shaft in said forward torque direction but unlocking said first gear element in said reverse torque direction; and locking said first gear element for rotation with said shaft in said reverse torque direction but unlocking said first gear element in said forward torque direction.

11. 8. The transmission system of claim 7, wherein with said first gear element engaged by said first and second sets of engaging members and locked for rotation in forward and reverse torque directions, one of said first and second sets of engaging members is in a loaded condition and the other of said first and second sets of engaging members is in an unloaded condition.

12. 12. A transmission system according to claim 11, wherein the actuator assembly is arranged to selectively move the unloaded set of engagement members out of engagement with the first gear element, e.g., to a neutral position.

13. 2. The transmission system of claim 1, wherein said first gear selector assembly is arranged to selectively engage said second gear element in the following modes of operation: locking said second gear element for rotation with said shaft in both forward and reverse torque directions; locking said second gear element for rotation with said shaft in said forward torque direction but unlocking said second gear element in said reverse torque direction; and locking said second gear element for rotation with said shaft in said reverse torque direction but unlocking said second gear element in said forward torque direction.

14. 8. The transmission system of claim 7, wherein with said second gear element engaged by said first and second sets of engaging members and locked for rotation in forward and reverse torque directions, one of said first and second sets of engaging members is in a loaded condition and the other of said first and second sets of engaging members is in an unloaded condition.

15. 15. A transmission system according to claim 14, wherein the actuator assembly is arranged to selectively move the unloaded set of engagement members out of engagement with the second gear element, e.g., to a neutral position.

16. 9. The transmission system of claim 8, wherein said first selector assembly is mounted to said shaft by a support sleeve, said support sleeve including internal splines arranged to lock said support sleeve for rotation with said shaft.

17. 17. The transmission system of claim 16, wherein at least one, and preferably each, of the engagement members in the first set of engagement members includes a linear feature formed on an inwardly facing side thereof and positioned to engage a complementary feature on the support sleeve.

18. 17. The transmission system of claim 16, wherein at least one, and preferably each, of the engagement members in the second set of engagement members includes a linear feature formed on an inwardly facing side thereof and positioned to engage a complementary feature on the support sleeve.

19. 2. The transmission system of claim 1, wherein said first gear selector assembly is arranged to provide torque support during gear shifting to ensure there is no loss of drive during said gear shifting.

20. 8. The transmission system of claim 7 including a second gear selector assembly and a third gear selector assembly, said actuator assembly positioned to control operation of said second and third gear selector assemblies.

21. 21. The transmission system of claim 20, wherein the actuator assembly includes a shift drum having first and second portions, the second portion arranged to rotate relative to the first portion, the second portion including a first control slot arranged to control operation of the first selector assembly and a second control slot arranged to control operation of the second gear selector assembly, and the first portion including a third control slot arranged to control operation of the third gear selector assembly.

22. 8. The transmission system of claim 7, wherein the actuator assembly includes a first shift fork assembly, the first shift fork assembly including a first shift fork positioned to control axial movement of the first selector ring and a second shift fork positioned to control axial movement of the second selector ring.

23. 8. The transmission system of claim 7, wherein the actuator assembly includes a first shift collar mounted to a first shift rail, the first shift collar including a first control member that engages the first control slot, and the shift drum is positioned to adjust the position of the first control member along the first control slot to control the axial position of the first collar relative to the first shift rail by adjusting the rotational direction of the second portion of the shift drum.

24. 21. The transmission system of claim 20, wherein said second gear selector assembly includes a third selector ring, and said actuator assembly includes a second shift fork assembly, said second shift fork assembly including a third shift fork positioned to control axial movement of said third selector ring.

25. 21. The transmission system of claim 20, including a first input shaft directly connected to the output of a drive source, and a second input shaft connected to the output of the drive source through a friction clutch.

26. 26. The transmission of claim 25, wherein the second gear selector assembly is mounted on the second input shaft, a third gear element is rotatably mounted on the second input shaft, and a fourth gear element is rotatably mounted on the second input shaft, the second gear selector assembly being arranged to selectively lock each of the third and fourth gear elements for rotation with the second input shaft.

27. 21. The transmission system of claim 20, wherein odd gears are grouped together in a first portion of the transmission and even gears are grouped together in a second portion of the transmission, and wherein the second gear selector assembly is positioned to select between the odd and even gears by selectively forming torque paths to the first and second portions of the transmission.

28. 2. The transmission system of claim 1, wherein the third gear selector assembly includes a further selector ring, and the actuator assembly includes a further shift fork assembly, the further shift fork assembly including a further shift fork positioned to control axial movement of the further selector ring.

29. 2. The transmission system of claim 1, including an output shaft, wherein the third gear selector assembly is mounted on one of the output shaft, the second counter shaft, and a sleeve mounted on the second counter shaft, and at least one further gear element is rotatably mounted coaxially with the third gear selector assembly, the third gear selector assembly being arranged to selectively lock the at least one further gear element for rotation with the shaft on which it is mounted.

30. 2. The transmission system of claim 1, wherein said third gear selector assembly comprises a preselection selector assembly arranged to provide a new preselection.

31. 31. A drive train comprising a drive source, a friction clutch device, and a transmission system according to any one of claims 1 to 30.

32. 32. The drive train of claim 31, wherein the friction clutch device is a wet friction clutch or a dry friction clutch.

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