FIELD OF THE DISCLOSURE

[0001] The present disclosure relates to a multiple speed transmission, and in particular to a multiple speed transmission capable of achieving eight or more speeds.

BACKGROUND

[0001] Multiple speed transmissions use a number of friction clutches or brakes, planetary gearsets, shafts, and other elements to achieve a plurality of gear or speed ratios. The architecture, i.e., packaging or layout of the aforementioned elements, is determined based on cost, size, packaging constraints, and desired ratios. There is a need for new architectural designs of multiple speed transmissions for achieving different ratios with improved performance, cost, efficiency, responsiveness, and packaging.

SUMMARY

[0002] In one embodiment of the present disclosure, a multiple speed transmission includes an input member; an output member; first, second, third and fourth planetary gearsets each having first, second and third members; a plurality of interconnecting members each connected between at least one of the first, second, third, and fourth planetary gearsets and at least another of the first, second, third, and fourth planetary gearsets; a first torque- transmitting mechanism selectively engageable to interconnect the first member of the first planetary gearset and the first member of the second planetary gearset with a stationary member; a second torque-transmitting mechanism selectively engageable to interconnect the third member of the first planetary gearset with the stationary member; a third torque- transmitting mechanism selectively engageable to interconnect the second member of the second planetary gearset with the first member of the fourth planetary gearset; a fourth torque-transmitting mechanism selectively engageable to interconnect the third member of the second planetary gearset and the first member of the third planetary gearset with the first member of the fourth planetary gearset; and a fifth torque-transmitting mechanism

selectively engageable to interconnect the third member of the third planetary gearset with the first member of the fourth planetary gearset; wherein the torque transmitting mechanisms are selectively engageable in combinations of at least three to establish at least eight forward speed ratios and at least one reverse speed ratio between the input member and the output member.

[0003] In one example of this embodiment, the input member is continuously

interconnected with the second member of the second planetary gearset and the output member is continuously interconnected with the second member of the fourth planetary gearset. In a second example, the plurality of interconnecting members includes a first interconnecting member continuously interconnecting the first member of the first planetary gearset with the first member of the second planetary gearset. In a third example, the plurality of interconnecting members includes a second interconnecting member

continuously interconnecting the second member of the first planetary gearset with the second member of the third planetary gearset and the third member of the fourth planetary gearset.

[0004] In a fourth example of this embodiment, the plurality of interconnecting members includes a third interconnecting member continuously interconnecting the third member of the second planetary gearset with the first member of the third planetary gearset. In a fifth example, the first, second, and third members of the first, second, third, and fourth planetary gearsets are each at least one of a sun gear, a ring gear, and a carrier member. In a sixth example, the first members are sun gears, the second members are carrier members, and the third members are ring gears. In a seventh example, each of the plurality of interconnecting members are rotationally fixed between at least one of the first, second, third, and fourth planetary gearsets and at least another of the first, second, third, and fourth planetary gearsets.

[0005] In another embodiment, a multiple speed transmission includes an input member; an output member; first, second, third and fourth planetary gearsets each having a sun gear, a carrier member, and a ring gear, wherein the input member and the output member are each interconnected to at least one of the first, second, third, and fourth planetary gearsets; a first torque-transmitting mechanism selectively engageable to interconnect the sun gear of the first planetary gearset and the sun gear of the second planetary gearset with a stationary member; a second torque-transmitting mechanism selectively engageable to interconnect the ring gear of the first planetary gearset with the stationary member; a third torque-transmitting mechanism selectively engageable to interconnect the carrier member of the second planetary gearset with the sun gear of the fourth planetary gearset; a fourth torque-transmitting mechanism selectively engageable to interconnect the ring gear of the second planetary gearset and the sun gear of the third planetary gearset with the sun gear of the fourth planetary gearset; and a fifth torque-transmitting mechanism selectively engageable to interconnect the ring gear of the third planetary gearset with the sun gear of the fourth planetary gearset; wherein the torque transmitting mechanisms are selectively engageable in combinations of at least three to establish at least eight forward speed ratios and at least one reverse speed ratio between the input member and the output member.

[0006] In one example of this embodiment, a first interconnecting member continuously interconnects the sun gear of the first planetary gearset with the sun gear of the second planetary gearset. In a second example, a second interconnecting member continuously interconnects the carrier member of the first planetary gearset with the carrier member of the third planetary gearset and the ring gear of the fourth planetary gearset. In a third example, a third interconnecting member continuously interconnects the ring gear of the second planetary gearset with the sun gear of the third planetary gearset. In a fourth example, the input member is continuously interconnected with the carrier member of the second planetary gearset, and the output member is continuously interconnected with the carrier member of the fourth planetary gearset.

[0007] In a different embodiment, a multiple speed transmission includes an input member; an output member; first, second, third and fourth planetary gearsets each having first, second and third members; a plurality of interconnecting members each connected between at least one of the first, second, third, and fourth planetary gearsets and at least another of the first, second, third, and fourth planetary gearsets; a first torque-transmitting mechanism selectively engageable to interconnect the first member of the first planetary gearset and the first member of the second planetary gearset with a stationary member; a second torque-transmitting mechanism selectively engageable to interconnect the third member of the first planetary gearset with the stationary member; a third torque-transmitting 1

mechanism selectively engageable to interconnect the second member of the second planetary gearset with the first member of the third planetary gearset and the first member of the fourth planetary gearset; a fifth torque-transmitting mechanism selectively engageable to interconnect the third member of the second planetary gearset and the third member of the third planetary gearset; and a fourth torque -transmitting mechanism selectively engageable to interconnect the third member of the second planetary gearset with the first member of the third planetary gearset and the first member of the fourth planetary gearset; wherein the torque transmitting mechanisms are selectively engageable in combinations of at least three to establish at least eight forward speed ratios and at least one reverse speed ratio between the input member and the output member.

[0008] In one example of this embodiment, the input member is continuously

interconnected with the second member of the second planetary gearset and the output member is continuously interconnected with the second member of the fourth planetary gearset. In a second example, the plurality of interconnecting members includes a first interconnecting member continuously interconnecting the first member of the first planetary gearset with the first member of the second planetary gearset. In a third example, the plurality of interconnecting members includes a second interconnecting member

continuously interconnecting the second member of the first planetary gearset with the second member of the third planetary gearset and the third member of the fourth planetary gearset. In a fourth example, the plurality of interconnecting members includes a third interconnecting member continuously interconnecting the first member of the third planetary gearset with the first member of the fourth planetary gearset.

[0009] In a further embodiment of the present disclosure, a multiple speed transmission includes an input member; an output member; first, second, third and fourth planetary gearsets each having a sun gear, a carrier member, and a ring gear, wherein the input member and the output member are each interconnected to at least one of the first, second, third, and fourth planetary gearsets; a first torque-transmitting mechanism selectively engageable to interconnect the sun gear of the first planetary gearset and the sun gear of the second planetary gearset with a stationary member; a second torque-transmitting mechanism selectively engageable to interconnect the ring gear of the first planetary gearset with the stationary member; a third torque-transmitting mechanism selectively engageable to interconnect the carrier member of the second planetary gearset with the sun gear of the third planetary gearset and the sun gear of the fourth planetary gearset; a fifth torque-transmitting mechanism selectively engageable to interconnect the ring gear of the second planetary gearset with the ring gear of the third planetary gearset; and a fourth torque-transmitting mechanism selectively engageable to interconnect the ring gear of the second planetary gearset with the sun gear of the third planetary gearset and the sun gear of the fourth planetary gearset; wherein the torque transmitting mechanisms are selectively engageable in combinations of at least three to establish at least eight forward speed ratios and at least one reverse speed ratio between the input member and the output member.

[0010] In one example of this embodiment, a first interconnecting member continuously interconnects the sun gear of the first planetary gearset with the sun gear of the second planetary gearset. In a second example, a second interconnecting member continuously interconnects the carrier member of the first planetary gearset with the carrier member of the third planetary gearset and the ring gear of the fourth planetary gearset. In a third example, a third interconnecting member continuously interconnects the sun gear of the third planetary gearset with the sun gear of the fourth planetary gearset.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The above-mentioned aspects of the present disclosure and the manner of obtaining them will become more apparent and the disclosure itself will be better understood by reference to the following description of the embodiments of the disclosure, taken in conjunction with the accompanying drawings, wherein:

[0012] Fig. 1 is an exemplary block diagram and schematic view of one illustrative embodiment of a powered vehicular system;

[0013] Fig. 2 is a diagrammatic view of one embodiment of a multiple speed

transmission;

[0014] Fig. 3 is a diagrammatic view of another embodiment of a multiple speed transmission; and [0015] Fig. 4 is a truth table presenting an example of a state of engagement of various torque transmitting mechanisms in each of the available forward and reverse speeds or gear ratios of the transmission illustrated in Figs. 2 and 3.

[0016] Corresponding reference numerals are used to indicate corresponding parts throughout the several views.

DETAILED DESCRIPTION

[0017] The embodiments of the present disclosure described below are not intended to be exhaustive or to limit the disclosure to the precise forms disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may appreciate and understand the principles and practices of the present disclosure.

[0018] Referring now to Fig. 1 , a block diagram and schematic view of one illustrative embodiment of a vehicular system 100 having a drive unit 102 and transmission 1 18 is shown. In the illustrated embodiment, the drive unit 102 may include an internal combustion engine, diesel engine, electric motor, or other power-generating device. The drive unit 102 is configured to rotatably drive an output shaft 104 that is coupled to an input or pump shaft 106 of a conventional torque converter 108. The input or pump shaft 106 is coupled to an impeller or pump 1 10 that is rotatably driven by the output shaft 104 of the drive unit 102. The torque converter 108 further includes a turbine 1 12 that is coupled to a turbine shaft 1 14, and the turbine shaft 1 14 is coupled to, or integral with, a rotatable input shaft 124 of the transmission 1 18. The transmission 1 18 can also include an internal pump 120 for building pressure within different flow circuits (e.g., main circuit, lube circuit, etc.) of the

transmission 1 18. The pump 120 can be driven by a shaft 1 16 that is coupled to the output shaft 104 of the drive unit 102. In this arrangement, the drive unit 102 can deliver torque to the shaft 1 16 for driving the pump 120 and building pressure within the different circuits of the transmission 1 18.

[0019] The transmission 1 18 can include a planetary gear system 122 having a number of automatically selected gears. An output shaft 126 of the transmission 118 is coupled to or integral with, and rotatably drives, a propeller shaft 128 that is coupled to a conventional universal joint 130. The universal joint 130 is coupled to, and rotatably drives, an axle 132 having wheels 134 A and 134B mounted thereto at each end. The output shaft 126 of the transmission 1 18 drives the wheels 134A and 134B in a conventional manner via the propeller shaft 128, universal joint 130 and axle 132.

[0020] A conventional lockup clutch 136 is connected between the pump 1 10 and the turbine 1 12 of the torque converter 108. The operation of the torque converter 108 is conventional in that the torque converter 108 is operable in a so-called "torque converter" mode during certain operating conditions such as vehicle launch, low speed and certain gear shifting conditions. In the torque converter mode, the lockup clutch 136 is disengaged and the pump 1 10 rotates at the rotational speed of the drive unit output shaft 104 while the turbine 1 12 is rotatably actuated by the pump 1 10 through a fluid (not shown) interposed between the pump 1 10 and the turbine 1 12. In this operational mode, torque multiplication occurs through the fluid coupling such that the turbine shaft 1 14 is exposed to drive more torque than is being supplied by the drive unit 102, as is known in the art. The torque converter 108 is alternatively operable in a so-called "lockup" mode during other operating conditions, such as when certain gears of the planetary gear system 122 of the transmission 1 18 are engaged. In the lockup mode, the lockup clutch 136 is engaged and the pump 1 10 is thereby secured directly to the turbine 1 12 so that the drive unit output shaft 104 is directly coupled to the input shaft 124 of the transmission 1 18, as is also known in the art.

[0021] The transmission 1 18 further includes an electro-hydraulic system 138 that is fluidly coupled to the planetary gear system 122 via a number, J, of fluid paths, 140 _! -140j, where J may be any positive integer. The electro-hydraulic system 138 is responsive to control signals to selectively cause fluid to flow through one or more of the fluid paths, 140j- 140j, to thereby control operation, i.e., engagement and disengagement, of a plurality of corresponding friction devices in the planetary gear system 122. The plurality of friction devices may include, but are not limited to, one or more conventional brake devices, one or more torque transmitting devices, and the like. Generally, the operation, i.e., engagement and disengagement, of the plurality of friction devices is controlled by selectively controlling the friction applied by each of the plurality of friction devices, such as by controlling fluid pressure to each of the friction devices. In one example embodiment, which is not intended to be limiting in any way, the plurality of friction devices include a plurality of brake and torque transmitting devices in the form of conventional clutches that may each be

controllably engaged and disengaged via fluid pressure supplied by the electro-hydraulic system 138. In any case, changing or shifting between the various gears of the transmission 1 18 is accomplished in a conventional manner by selectively controlling the plurality of friction devices via control of fluid pressure within the number of fluid paths 140I-140J.

[0022] The system 100 further includes a transmission control circuit 142 that can include a memory unit 144. The transmission control circuit 142 is illustratively

microprocessor-based, and the memory unit 144 generally includes instructions stored therein that are executable by a processor of the transmission control circuit 142 to control operation of the torque converter 108 and operation of the transmission 1 18, i.e., shifting between the various gears of the planetary gear system 122. It will be understood, however, that this disclosure contemplates other embodiments in which the transmission control circuit 142 is not microprocessor-based, but is configured to control operation of the torque converter 108 and/or transmission 1 18 based on one or more sets of hardwired instructions and/or software instructions stored in the memory unit 144.

[0023] In the system 100 illustrated in Fig. 1, the torque converter 108 and the

transmission 1 18 include a number of sensors configured to produce sensor signals that are indicative of one or more operating states of the torque converter 108 and transmission 1 18, respectively. For example, the torque converter 108 illustratively includes a conventional speed sensor 146 that is positioned and configured to produce a speed signal corresponding to the rotational speed of the pump shaft 106, which is the same rotational speed of the output shaft 104 of the drive unit 102. The speed sensor 146 is electrically connected to a pump speed input, PS, of the transmission control circuit 142 via a signal path 152, and the transmission control circuit 142 is operable to process the speed signal produced by the speed sensor 146 in a conventional manner to determine the rotational speed of the pump shaft 106/drive unit output shaft 104.

[0024] The transmission 1 18 illustratively includes another conventional speed sensor 148 that is positioned and configured to produce a speed signal corresponding to the rotational speed of the transmission input shaft 124, which is the same rotational speed as the turbine shaft 1 14. The input shaft 124 of the transmission 1 18 is directly coupled to, or integral with, the turbine shaft 1 14, and the speed sensor 148 may alternatively be positioned and configured to produce a speed signal corresponding to the rotational speed of the turbine shaft 114. In any case, the speed sensor 148 is electrically connected to a transmission input shaft speed input, TIS, of the transmission control circuit 142 via a signal path 154, and the transmission control circuit 142 is operable to process the speed signal produced by the speed sensor 148 in a conventional manner to determine the rotational speed of the turbine shaft 1 14/transmission input shaft 124.

[0025] The transmission 1 18 further includes yet another speed sensor 150 that is positioned and configured to produce a speed signal corresponding to the rotational speed of the output shaft 126 of the transmission 1 18. The speed sensor 150 may be conventional, and is electrically connected to a transmission output shaft speed input, TOS, of the transmission control circuit 142 via a signal path 156. The transmission control circuit 142 is configured to process the speed signal produced by the speed sensor 150 in a conventional manner to determine the rotational speed of the transmission output shaft 126.

[0026] In the illustrated embodiment, the transmission 1 18 further includes one or more actuators configured to control various operations within the transmission 1 18. For example, the electro-hydraulic system 138 described herein illustratively includes a number of actuators, e.g., conventional solenoids or other conventional actuators, that are electrically connected to a number, J, of control outputs, CP _\ - CPj, of the transmission control circuit 142 via a corresponding number of signal paths 721 - 72j, where J may be any positive integer as described above. The actuators within the electro-hydraulic system 138 are each responsive to a corresponding one of the control signals, CPi - CPj, produced by the transmission control circuit 142 on one of the corresponding signal paths 72 ₁ - 72j to control the friction applied by each of the plurality of friction devices by controlling the pressure of fluid within one or more corresponding fluid passageway 140i - 140j, and thus control the operation, i.e., engaging and disengaging, of one or more corresponding friction devices, based on information provided by the various speed sensors 146, 148, and/or 150.

[0027] The friction devices of the planetary gear system 122 are illustratively controlled by hydraulic fluid which is distributed by the electro-hydraulic system in a conventional manner. For example, the electro-hydraulic system 138 illustratively includes a conventional hydraulic positive displacement pump (not shown) which distributes fluid to the one or more friction devices via control of the one or more actuators within the electro-hydraulic system 138. In this embodiment, the control signals, CPi - CPj, are illustratively analog friction device pressure commands to which the one or more actuators are responsive to control the hydraulic pressure to the one or more frictions devices. It will be understood, however, that the friction applied by each of the plurality of friction devices may alternatively be controlled in accordance with other conventional friction device control structures and techniques, and such other conventional friction device control structures and techniques are contemplated by this disclosure. In any case, however, the analog operation of each of the friction devices is controlled by the control circuit 142 in accordance with instructions stored in the memory unit 144.

[0028] In the illustrated embodiment, the system 100 further includes a drive unit control circuit 160 having an input/output port (I/O) that is electrically coupled to the drive unit 102 via a number, K, of signal paths 162, wherein K may be any positive integer. The drive unit control circuit 160 may be conventional, and is operable to control and manage the overall operation of the drive unit 102. The drive unit control circuit 160 further includes a communication port, COM, which is electrically connected to a similar communication port, COM, of the transmission control circuit 142 via a number, L, of signal paths 164, wherein L may be any positive integer. The one or more signal paths 164 are typically referred to collectively as a data link. Generally, the drive unit control circuit 160 and the transmission control circuit 142 are operable to share information via the one or more signal paths 164 in a conventional manner. In one embodiment, for example, the drive unit control circuit 160 and transmission control circuit 142 are operable to share information via the one or more signal paths 164 in the form of one or more messages in accordance with a society of automotive engineers (SAE) J- 1939 communications protocol, although this disclosure contemplates other embodiments in which the drive unit control circuit 160 and the transmission control circuit 142 are operable to share information via the one or more signal paths 164 in accordance with one or more other conventional communication protocols (e.g., from a conventional databus such as J1587 data bus, J1939 data bus, IESCAN data bus, GMLAN, Mercedes PT-CAN). [0029] Referring to Fig. 2, a schematic representation or stick diagram illustrates one embodiment of a multi-speed transmission 200 according to the present disclosure. The transmission 200 includes an input shaft 202 and an output shaft 204. The input shaft 202 and output shaft 204 can be disposed along the same axis or centerline of the transmission 200. In another aspect, the different shafts can be disposed along different axes or centerlines. In a further aspect, the different shafts can be disposed parallel to one another, but along different axes or centerlines. Other aspect can be appreciated by one skilled in the art.

[0030] The transmission 200 can also include a plurality of planetary gearsets. In the illustrated embodiment of Fig. 2, the transmission 200 includes a first planetary gearset 206, a second planetary gearset 208, a third planetary gearset 210, and a fourth planetary gearset 212. Each planetary gearset can be referred to as a simple or compound planetary gearset. For example, in some aspects, one or more of the plurality of planetary gearsets can be formed as an idler planetary gearset, although in Fig. 2 each planetary gearset is illustrated as a simple planetary gearset. One or more of the plurality of planetary gearsets can be arranged in different locations within the transmission 200, but for sake of simplicity and in this particular example only, the planetary gearsets are aligned in an axial direction consecutively in sequence (i.e., first, second, third, and fourth between the input and output shafts).

[0031] The transmission 200 may also include a plurality of torque-transmitting or gearshifting mechanisms. For example, one or more of these mechanisms can include a clutch or brake. In one aspect, each of the plurality of mechanisms is disposed within an outer housing of the transmission 200. In another aspect, however, one or more of the mechanisms may be disposed outside of the housing. Each of the plurality of mechanisms can be coupled to one or more of the plurality of planetary gearsets, which will be described further below.

[0032] In the embodiment of Fig. 2, the transmission 200 can include a first torque- transmitting mechanism 258 and a second torque-transmitting mechanism 260 that are configured to function as brakes (e.g., each torque-transmitting mechanism is fixedly coupled to the outer housing of the transmission 200). These brakes can be configured as shiftable- friction-locked disk brakes, shiftable friction-locked band brakes, shiftable form-locking claw or conical brakes, or any other type of known brake. The transmission 200 can include a third torque-transmitting mechanism 262, a fourth torque-transmitting mechanism 264, and a fifth torque-transmitting mechanism 266 that are configured to function as clutches. These can be shiftable friction-locked multi-disk clutches, shiftable form-locking claw or conical clutches, wet clutches, or any other known form of a clutch. With these five torque- transmitting mechanisms, selective shifting of at least eight forward gears and at least one reverse gear is possible.

[0033] The transmission 200 of Fig. 2 may also include up to eight different shafts, which is inclusive of the input shaft 202 and output shaft 204. Each of these shafts, designated as a first shaft 222, a second shaft 224, a third shaft 226, a fourth shaft 236, a fifth shaft 246, and a sixth shaft 248, are configured to be connected to one or more of the plurality of planetary gearsets or plurality of torque-transmitting mechanism between the input shaft 202 and output shaft 204.

[0034] In Fig. 2, the first planetary gearset 206 can include a first sun gear 214, a first ring gear 216, and a first carrier member 218 that rotatably supports a set of pinion gears 220. The second planetary gearset 208 can include a second sun gear 228, a second ring gear 230, and a second carrier member 232 that rotatably supports a set of pinion gears 234. The third planetary gearset 210 can include a third sun gear 238, a third ring gear 240, and a third carrier member 242 that rotatably supports a set of pinion gears 244. The fourth planetary gearset 212 can include a fourth sun gear 250, a fourth ring gear 252, and a fourth carrier member 254 that rotatably supports a set of pinion gears 256.

[0035] The transmission 200 is capable of transferring torque from the input shaft 202 to the output shaft 204 in at least eight forward gears or ratios and at least one reverse gear or ratio. Each of the forward torque ratios and the reverse torque ratios can be attained by the selective engagement of one or more of the torque-transmitting mechanisms (i.e., torque- transmitting mechanisms 258, 260, 262, 264, and 266). Those skilled in the art will readily understand that a different speed ratio is associated with each torque ratio. Thus, at least eight forward speed ratios and at least one reverse speed ratio may be attained by

transmission 200. An example of the gear ratios that may be obtained using the embodiments of the present disclosure are also shown in Fig. 4. Of course, other gear ratios are achievable depending on the gear diameter, gear tooth count and gear configuration selected.

[0036] As for the transmission 200, kinematic coupling of the first planetary gearset 206 is shown in Fig. 2. The first sun gear 214 is coupled to the first shaft 222 for common rotation therewith. The first ring gear 216 is coupled to the second shaft 224 for common rotation therewith. First pinion gears 220 are configured to intermesh with the first sun gear 214 and first ring gear 216. First carrier member 218 is coupled for common rotation with the third shaft 226.

[0037] With respect to the second planetary gearset 208, the second sun gear 228 is coupled to the first shaft 222 and first sun gear 214 for common rotation therewith. The second ring gear 230 is coupled to the fourth shaft 236 for common rotation therewith. Second pinion gears 234 are configured to intermesh with the second sun gear 228 and second ring gear 230, and the second carrier member 232 is coupled for common rotation with the input shaft 202.

[0038] The third sun gear 238 of the third planetary gearset 210 is coupled to the fourth shaft 236 as well, and thus is disposed in common rotation with the second ring gear 230. The third ring gear 240 is coupled to the fifth shaft 246 for common rotation therewith. Third pinion gears 244 are configured to intermesh with the third sun gear 238 and third ring gear 240, and the third carrier member 242 is coupled for common rotation with the third shaft 226. Thus, the third carrier member 242 is disposed in common rotation with the first carrier member 218 as well.

[0039] The kinematic relationship of the fourth planetary gearset 212 is such that the fourth sun gear 250 is coupled to the sixth shaft 248 for common rotation therewith. The fourth ring gear 252 is coupled to the third shaft 226 for common rotation therewith.

Moreover, the kinematic coupling of the third shaft 226 and fourth ring gear 252 further couples the fourth ring gear 252 to the first carrier member 218 and third carrier member 242 via the third shaft 226. The fourth pinions 256 are configured to intermesh with the fourth sun gear 250 and the fourth ring gear 252. The fourth carrier member 254 is coupled to the output shaft 204 for common rotation therewith. [0040] With regards to the kinematic coupling of the five torque-transmitting

mechanisms to the previously described shafts, the multiple speed transmission 200 of Fig. 2 provides that the first torque-transmitting mechanism 258 is arranged within the power flow between the first shaft 222 and the housing G of the transmission 200. In this manner, the first torque-transmitting mechanism 258 is configured to act as a brake. Similarly, the second torque-transmitting mechanism 260 is arranged within the power flow between the second shaft 224 and the housing G of the transmission 200. Thus, similar to the first torque- transmitting mechanism 258, the second torque-transmitting mechanism 260 is configured to act as a brake. In this embodiment of the transmission 200 therefore two of the five torque- transmitting mechanism are configured to act as brakes and the other three torque- transmitting mechanisms are configured to act as clutches.

[0041] The third torque-transmitting mechanism 262 is arranged within the power flow between the input shaft 202 and the sixth shaft 248. The fourth torque-transmitting mechanism 264 is arranged within the power flow between the fourth shaft 236 and the sixth shaft 248. Moreover, the fifth torque-transmitting mechanism 266 is arranged within the power flow between the fifth shaft 246 and the sixth shaft 248.

[0042] The kinematic couplings of the embodiment in Fig. 2 can further be described with respect to the selective engagement of the torque-transmitting mechanisms with respect to one or more components of the plurality of planetary gearsets. For example, in the transmission 200, the first torque-transmitting mechanism 258 is selectively engageable to couple the first sun gear 214, the second sun gear 228, and the first shaft 222 to the housing G of the transmission 200. The second torque-transmitting mechanism 260 is selectively engageable to couple the first ring gear 216 and the second shaft 224 to the housing G of the transmission 200. Moreover, the third torque-transmitting mechanism 262 is selectively engageable to couple the input shaft 202 and the second carrier 232 to the sixth shaft 248 and fourth sun gear 250. The fourth torque-transmitting mechanism 264 is selectively

engageable to couple the second ring gear 230, the third sun gear 238, and the fourth shaft 236 to the fourth sun gear 250 and the sixth shaft 248. Lastly, the fifth torque-transmitting mechanism 266 is selectively engageable to couple the third ring gear 240 and the fifth shaft 246 to the fourth sun gear 250 and the sixth shaft 248. [0043] Referring to Fig. 3, a different embodiment of a multiple speed transmission 300 is shown. The transmission 300 includes an input shaft 302 and an output shaft 304. The input shaft 302 and output shaft 304 can be disposed along the same axis or centerline of the transmission 300. In another aspect, the different shafts can be disposed along different axes or centerlines. In a further aspect, the different shafts can be disposed parallel to one another, but along different axes or centerlines. Other aspect can be appreciated by one skilled in the art.

[0044] The transmission 300 can also include a plurality of planetary gearsets. In the illustrated embodiment of Fig. 3, the transmission 300 includes a first planetary gearset 306, a second planetary gearset 308, a third planetary gearset 310, and a fourth planetary gearset 312. Each planetary gearset can be referred to as a simple or compound planetary gearset. For example, in some aspects, one or more of the plurality of planetary gearsets can be formed as an idler planetary gearset, although in Fig. 3 each planetary gearset is illustrated as a simple planetary gearset. One or more of the plurality of planetary gearsets can be arranged in different locations within the transmission 300, but for sake of simplicity and in this particular example only, the planetary gearsets are aligned in an axial direction consecutively in sequence (i.e., first, second, third, and fourth between the input and output shafts).

[0045] The transmission 300 may also include a plurality of torque-transmitting or gearshifting mechanisms. For example, one or more of these mechanisms can include a clutch or brake. In one aspect, each of the plurality of mechanisms is disposed within an outer housing of the transmission 300. In another aspect, however, one or more of the mechanisms may be disposed outside of the housing. Each of the plurality of mechanisms can be coupled to one or more of the plurality of planetary gearsets, which will be described further below.

[0046] In the embodiment of Fig. 3, the transmission 300 can include a first torque- transmitting mechanism 358 and a second torque-transmitting mechanism 360 that are configured to function as brakes (e.g., each torque-transmitting mechanism is fixedly coupled to the outer housing G of the transmission 300). These brakes can be configured as shiftable- friction-locked disk brakes, shiftable friction-locked band brakes, shiftable form-locking claw or conical brakes, or any other type of known brake. The transmission 300 can include a third torque-transmitting mechanism 362, a fifth torque-transmitting mechanism 364, and a fourth torque-transmitting mechanism 366 that are configured to function as clutches. These can be shiftable friction-locked multi-disk clutches, shiftable form-locking claw or conical clutches, wet clutches, or any other known form of a clutch. With these five torque- transmitting mechanisms, selective shifting of at least eight forward gears and at least one reverse gear is possible.

[0047] The transmission 300 of Fig. 3 may also include up to eight different shafts, which is inclusive of the input shaft 302 and output shaft 304. Each of these shafts, designated as a first shaft 322, a second shaft 324, a third shaft 326, a fourth shaft 336, a fifth shaft 346, and a sixth shaft 348, are configured to be connected to one or more of the plurality of planetary gearsets or plurality of torque-transmitting mechanism between the input shaft 302 and output shaft 304.

[0048] In Fig. 3, the first planetary gearset 306 can include a first sun gear 314, a first ring gear 316, and a first carrier member 318 that rotatably supports a set of pinion gears 320. The second planetary gearset 308 can include a second sun gear 328, a second ring gear 330, and a second carrier member 332 that rotatably supports a set of pinion gears 334. The third planetary gearset 310 can include a third sun gear 338, a third ring gear 340, and a third carrier member 342 that rotatably supports a set of pinion gears 344. The fourth planetary gearset 312 can include a fourth sun gear 350, a fourth ring gear 352, and a fourth carrier member 354 that rotatably supports a set of pinion gears 356.

[0049] The transmission 300 is capable of transferring torque from the input shaft 302 to the output shaft 304 in at least eight forward gears or ratios and at least one reverse gear or ratio. Each of the forward torque ratios and the reverse torque ratios can be attained by the selective engagement of one or more of the torque-transmitting mechanisms (i.e., torque- transmitting mechanisms 358, 360, 362, 364, and 366). Those skilled in the art will readily understand that a different speed ratio is associated with each torque ratio. Thus, at least eight forward speed ratios and at least one reverse speed ratio may be attained by

transmission 300. An example of the gear ratios that may be obtained using the

embodiments of the present disclosure are also shown in Fig. 4. Of course, other gear ratios are achievable depending on the gear diameter, gear tooth count and gear configuration selected.

[0050] As for the transmission 300, kinematic coupling of the first planetary gearset 306 is shown in Fig. 3. The first sun gear 314 is coupled to the first shaft 322 for common rotation therewith. The first ring gear 316 is coupled to the second shaft 324 for common rotation therewith. First pinion gears 320 are configured to intermesh with the first sun gear 314 and first ring gear 316. First carrier member 318 is coupled for common rotation with the third shaft 326.

[0051] With respect to the second planetary gearset 308, the second sun gear 328 is coupled to the first shaft 322 and first sun gear 314 for common rotation therewith. The second ring gear 330 is coupled to the fourth shaft 336 for common rotation therewith. Second pinion gears 334 are configured to intermesh with the second sun gear 328 and second ring gear 330, and the second carrier member 332 is coupled for common rotation with the input shaft 302.

[0052] The third sun gear 338 of the third planetary gearset 310 is coupled to the fifth shaft 346. The third ring gear 340 is coupled to the sixth shaft 348 for common rotation therewith. Third pinion gears 344 are configured to intermesh with the third sun gear 338 and third ring gear 340, and the third carrier member 342 is coupled for common rotation with the third shaft 326. Thus, the third carrier member 342 is disposed in common rotation with the first carrier member 318 as well.

[0053] The kinematic relationship of the fourth planetary gearset 312 is such that the fourth sun gear 350 is coupled to the fifth shaft 346 for common rotation therewith. The fourth ring gear 352 is coupled to the third shaft 326 for common rotation therewith, and thereby disposed in common rotation with the first carrier member 318 and the third carrier member 342. The fourth pinions 356 are configured to intermesh with the fourth sun gear 350 and the fourth ring gear 352. The fourth carrier member 354 is coupled to the output shaft 304 for common rotation therewith.

[0054] With regards to the kinematic coupling of the five torque-transmitting

mechanisms to the previously described shafts, the multiple speed transmission 300 of Fig. 3 provides that the first torque-transmitting mechanism 358 is arranged within the power flow between the first shaft 322 and the housing G of the transmission 300. In this manner, the first torque-transmitting mechanism 358 is configured to act as a brake. Similarly, the second torque-transmitting mechanism 360 is arranged within the power flow between the second shaft 324 and the housing G of the transmission 300. Thus, similar to the first torque- transmitting mechanism 358, the second torque-transmitting mechanism 360 is configured to act as a brake. In this embodiment of the transmission 300 therefore two of the five torque- transmitting mechanism are configured to act as brakes and the other three torque- transmitting mechanisms are configured to act as clutches.

[0055] The third torque-transmitting mechanism 362 is arranged within the power flow between the input shaft 302 and the fifth shaft 346. The fifth torque-transmitting mechanism 364 is arranged within the power flow between the fourth shaft 336 and the sixth shaft 348. Moreover, the fourth torque-transmitting mechanism 366 is arranged within the power flow between the fourth shaft 336 and the fifth shaft 346.

[0056] The kinematic couplings of the embodiment in Fig. 3 can further be described with respect to the selective engagement of the torque-transmitting mechanisms with respect to one or more components of the plurality of planetary gearsets. For example, in the transmission 300, the first torque-transmitting mechanism 358 is selectively engageable to couple the first sun gear 314, the second sun gear 328, and the first shaft 322 to the housing G of the transmission 300. The second torque-transmitting mechanism 360 is selectively engageable to couple the first ring gear 316 and the second shaft 324 to the housing G of the transmission 300. Moreover, the third torque-transmitting mechanism 362 is selectively engageable to couple the input shaft 302 and the second carrier 332 to the fifth shaft 346, the third sun gear 338 and fourth sun gear 350. The fifth torque-transmitting mechanism 364 is selectively engageable to couple the second ring gear 330 and fourth shaft 336 to the third ring gear 340 and sixth shaft 348. Lastly, the fourth torque-transmitting mechanism 366 is selectively engageable to couple the second ring gear 330 and the fourth shaft 336 to the third sun gear 338, the fourth sun gear 350 and the fifth shaft 346.

[0057] As previously described, each of the aforementioned embodiments is capable of transmitting torque from a respective input shaft to a respective output shaft in at least eight forward torque ratios and one reverse torque ratio. Referring to Fig. 4, one example of a truth table is shown representing a state of engagement of various torque transmitting mechanisms in each of the available forward and reverse speeds or gear ratios of the transmission illustrated in Figs. 2 and 3. It is to be understood that Fig. 4 is only one example of any number of truth tables possible for achieving at least eight forward ratios and one reverse ratio, and one skilled in the art is capable of configuring diameters, gear tooth counts, and gear configurations to achieve other ratios.

[0058] In the example of Fig. 4, the reverse ratio (Rev) can be achieved by the selective engagement of the torque-transmitting mechanisms as set forth in the table. As shown, the first torque transmitting mechanism (CI), second torque-transmitting mechanism (C2), and fifth torque-transmitting mechanism (C5) are selectively engaged to establish the reverse ratio. Thus, in transmission 200 of Fig. 2, the selective engagement of mechanisms 258, 260, and 266 can establish the reverse ratio, whereas in the transmission 300 of Fig. 3 the selective engagement of mechanisms 358, 360, and 364 can establish reverse.

[0059] In neutral (Neu), none of the torque-transmitting mechanisms carry torque. One or more of the torque-transmitting mechanisms, however, may be engaged in neutral but not carrying torque. For example, the first and second torque-transmitting mechanisms can be engaged in neutral, thereby resulting in the fifth torque-transmitting mechanism being disengaged between a shift between the one reverse ratio and neutral.

[0060] A first forward ratio (shown as 1st) in the table of Fig. 4 is achieved by engaging the first and second brakes and one of the clutches. In Fig. 2, for example, the first torque- transmitting mechanism 258, the second torque-transmitting mechanism 260, and the third torque-transmitting mechanism 262 are engaged. Thus, when transitioning between neutral and the first forward range, the first and second torque-transmitting mechanisms may already be engaged, and the third torque-transmitting mechanism is selectively engaged.

[0061] In a second or subsequent forward ratio, indicated as 2nd in Fig. 4, the first torque-transmitting mechanism, the second torque-transmitting mechanism, and the fourth torque-transmitting mechanism are selectively engaged. Therefore, when transitioning between the first forward ratio and the second forward ratio, the third torque-transmitting mechanism is released and the fourth torque-transmitting mechanism is engaged. [0062] In a third or subsequent forward ratio, indicated as 3rd forward ratio in Fig. 4, the second torque-transmitting mechanism, third torque-transmitting mechanism, and fourth torque-transmitting mechanism are engaged. To transition from the second forward ratio to the third forward ratio, for example, the first torque-transmitting mechanism is released and the third torque-transmitting mechanism is engaged.

[0063] In a fourth or the next subsequent forward ratio, indicated as 4th in Fig. 4, the second torque-transmitting mechanism, fourth torque-transmitting mechanism, and fifth torque-transmitting mechanism are engaged. Thus, to transition from the third forward ratio and upshift to the fourth forward ratio, the third torque-transmitting mechanism is released and the fifth torque-transmitting mechanism is engaged.

[0064] In a fifth or the next subsequent forward ratio, indicated as 5th in Fig. 4, the second torque-transmitting mechanism, third torque-transmitting mechanism, and fifth torque-transmitting mechanism are engaged. Thus, to transition from the fourth forward ratio and upshift to the fifth forward ratio, the fourth torque-transmitting mechanism is released and the third torque-transmitting mechanism is engaged.

[0065] In a sixth or the next subsequent forward ratio, indicated as 6th in Fig. 4, the third torque-transmitting mechanism, fourth torque-transmitting mechanism, and fifth torque- transmitting mechanism are engaged. Thus, to transition from the fifth forward ratio and upshift to the sixth forward ratio, the second torque-transmitting mechanism is released and the fourth torque-transmitting mechanism is engaged.

[0066] In a seventh or the next subsequent forward ratio, indicated as 7th in Fig. 4, the first torque-transmitting mechanism, third torque-transmitting mechanism, and fifth torque- transmitting mechanism are engaged. Thus, to transition from the sixth forward ratio and upshift to the seventh forward ratio, the fourth torque-transmitting mechanism is released and the first torque-transmitting mechanism is engaged.

[0067] In an eighth or the next subsequent forward ratio, indicated as 8th in Fig. 4, the first torque-transmitting mechanism, fourth torque-transmitting mechanism, and fifth torque- transmitting mechanism are engaged. Thus, to transition from the seventh forward ratio and upshift to the eighth forward ratio, the third torque-transmitting mechanism is released and the fourth torque-transmitting mechanism is engaged. [0068] The present disclosure contemplates that downshifts follow the reverse sequence of the corresponding upshift (as described above), and several power-on skip-shifts that are single-transition are possible (e.g. from 1st to 3rd or 3rd to 1st).

[0069] While exemplary embodiments incorporating the principles of the present disclosure have been disclosed hereinabove, the present disclosure is not limited to the disclosed embodiments. Instead, this application is intended to cover any variations, uses, or adaptations of the disclosure using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this disclosure pertains and which fall within the limits of the appended claims.