Nine-speed gearbox with locking mechanism

Abstract

Transmission (10) in a motor vehicle with a power engine, wherein the transmission (10) comprises: a gearbox housing (50); an input element (12); an output element (22); a first, second, third and fourth planetary gear set (14, 16, 18, 20), each comprising a sun gear (14C, 16A, 18A, 20A), a carrier element (14B, 16B, 18B, 20A) and, except for the fourth planetary gear set (20), a ring gear (14A, 16C, 18C); wherein the output element (22) is permanently connected to the carrier element (14B) of the first planetary gear set (14) and the ring gear (18C) of the third planetary gear set (18), a connecting element (44) that permanently connects the ring gear (14A) of the first planetary gear set (14) to the support element (16B) of the second planetary gear set (16); a first torque transmission mechanism (24) that can be selectively engaged to connect the input element (12) and the sun gear (16A) of the second planetary gear set (16) with the sun gear (18A) of the third planetary gear set (18); a second torque transmission mechanism (26) that can be selectively engaged to connect the input element (12) and the sun gear (16A) of the second planet gear set (16) to the ring gear (16C) of the second planet gear set (16), the carrier element (18B) of the third planet gear set (18) and the carrier element (20B) of the fourth planet gear set (20); a third torque transmission mechanism (28) that can be selectively engaged to connect the sun gear (20A) of the fourth planet gear set (20) to the ring gear (16C) of the second planet gear set (16), the carrier element (18B) of the third planet gear set (18) and the carrier element (20B) of the fourth planet gear set (20); a fourth torque transmission mechanism (30) that can be selectively engaged to connect the sun gear (18A) of the third planetary gear set (18) to the gearbox housing (50); a fifth torque transmission mechanism (32) which can be selectively engaged to connect the sun gear (20A) of the fourth planetary gear set (20) to the gearbox housing (50); a sixth torque transmission mechanism (34) which can be selectively engaged to connect the ring gear (16C) of the second planetary gear set (16), the carrier element (18B) of the third planetary gear set (18) and the carrier element (20B) of the fourth planetary gear set (20) to the gearbox housing (50); a seventh torque transmission mechanism (36) that can be selectively engaged to connect the sun gear (14C) of the first planetary gear set (14) to the gearbox housing (50); and a locking mechanism (102) connected to the sixth torque transmission mechanism (34), wherein the locking mechanism (102) locks the sixth torque transmission mechanism (34) in a ready state, wherein ready state refers to states of the sixth torque transmission mechanism (34) that include a filled state in which oil is fed into the circuits that actuate the sixth torque transmission mechanism (34), a pre-actuated state in which the sixth torque transmission mechanism (34) has been moved to near full engagement, and an engaged state in which the sixth torque transmission mechanism (34) is fully engaged and ready to transmit torque, or any other state in between, and wherein the seven torque transmission mechanisms (24, 26, 28, 3, 32, 34, 36) can be selectively engaged in combinations of two to produce nine forward speed ratios and one reverse speed ratio between the input element (12) and the output element (22), wherein the sixth torque transmission mechanism (34) is in the standby state during the first forward speed ratio and the reverse speed ratio, wherein the locking mechanism (102) locks the sixth torque transmission mechanism (34) in preparation for a stop event of the motor vehicle's engine.

Description

[0001] The invention relates to a transmission having nine gears, four planetary gear sets and seven torque transmitting mechanisms, one of which has a locking mechanism to enable automatic start / stop of an engine.

[0002] A typical automatic transmission includes a hydraulic control system used, among other functions, to operate a plurality of torque-transmitting devices and provide lubrication and cooling for the transmission's components. The conventional hydraulic control system typically includes a main pump that supplies a pressurized fluid, such as automatic transmission fluid, to a plurality of valves and solenoid valves within a valve body. The main pump is driven by the motor vehicle's engine. The valves and solenoid valves are operable to direct the pressurized hydraulic fluid through a hydraulic fluid circuit to the transmission's components. The pressurized hydraulic fluid delivered to the torque-transmitting devices is used, for example, to engage or disengage the devices to achieve different gear ratios.

[0003] To increase the fuel economy of motor vehicles, it is desirable to stop the engine under certain circumstances, such as when stopped at a red light or while idling. However, during this automatic stop, the pump is no longer driven by the engine. Accordingly, the hydraulic fluid pressure in the hydraulic control system drops. This causes clutches and / or brakes within the transmission to be completely disengaged. When the engine restarts, these clutches and / or brakes may take time to fully re-engage, creating slippage and delay between the engagement of the accelerator pedal or the release of the brake and the movement of the motor vehicle.Therefore, there is a need in the art for an automatic transmission capable of engine stop-start events such that the automatic start / stop event does not affect the performance of the transmission.

[0004] The subsequently published DE 10 2013 209 576 A1 and DE 10 2013 220 354 A1 disclose nine-speed transmissions with kinematics like those of the present invention, but without a locking mechanism for the sixth torque transmission mechanism.

[0005] From DE 10 2012 214 838 A1 it is known to provide locking mechanisms for three torque transmission mechanisms in an eight-speed transmission with five torque transmission mechanisms and different kinematics than those of the transmission of the present invention in order to reduce the requirements for the oil supply of the transmission when starting the engine after a start / stop event.

[0006] It is the object of the present invention to provide a nine-speed transmission capable of engine start / stop events such that the automatic start / stop event does not impair the performance of the transmission.

[0007] This object is achieved by a transmission having the features of claim 1.

[0008] The invention is described below by way of example with reference to the drawings: Fig. 1 is a lever diagram of a nine-speed transmission according to the principles of the present invention; Fig. Figure 2 is a schematic representation of the nine-speed transmission according to the principles of the present invention; Fig. 3 is a shift table showing the engagement state of the various torque-transmitting mechanisms in each of the available forward and reverse gears or gear ratios of the Fig. 1 and Fig. 2 illustrated gear; and Fig. 4 is a block diagram of the transmission with an engine start / stop enabling device.

[0009] In Fig. 1, a nine-speed transmission 10 is illustrated in a lever diagram format. A lever diagram is a schematic representation of the components of a mechanical device, such as an automatic transmission. Each individual lever represents a planetary gear set, with the three basic mechanical components of the planetary gear train each represented by a node. Therefore, a single lever contains three nodes: one for the sun gear, one for the planet carrier, and one for the ring gear. In some cases, two levers may be combined into a single lever having more than three nodes (typically four nodes). For example, if two nodes on two different levers are connected by a fixed connection, they may be represented as a single node on a single lever.The relative length between the nodes of each lever can be used to represent the ring gear / sun gear ratio of each corresponding gear set. These lever ratios are, in turn, used to vary the gear ratios of the transmission to achieve appropriate ratios and ratio progression. Mechanical couplings or connections between the nodes of the various planetary gear sets are illustrated by thin, horizontal lines, and torque-transmitting mechanisms, such as clutches and brakes, are represented as intermeshing fingers.

[0010] The transmission 10 includes an input shaft or input member 12, a first planetary gear set 14, a second planetary gear set 16, a third planetary gear set 18, and a fourth planetary gear set 20, and an output shaft or output member 22. The first planetary gear set 14 has three nodes: a first node 14A, a second node 14B, and a third node 14C. The second planetary gear set 16 has three nodes: a first node 16A, a second node 16B, and a third node 16C. In the lever diagram of Fig. 1, the levers for the third planetary gear set 18 and the fourth planetary gear set 20 have been combined into a single four-node lever comprising: a first node 18A, a second node 20A, a third node 18B, 20B, and a fourth node 18C, 20C. Thus, the second element 18B of the third planetary gear set 18 is directly coupled to the second element 20B of the fourth planetary gear set 20, and the third element 18C of the third planetary gear set 18 is directly coupled to the third element 20C of the fourth planetary gear set 20.

[0011] The input member 12 is continuously coupled to the first node 16A of the second planetary gear set 16. The output member 22 is continuously coupled to the second node 14B of the first planetary gear set 14 and the fourth node 18C, 20C of the combined levers of the third and fourth planetary gear sets 18, 20. The first node 14A of the first planetary gear set 14 is coupled to the second node 16B of the second planetary gear set 16. The third node 16C of the second planetary gear set 16 is coupled to the third node 18B, 20B of the combined levers of the third and fourth planetary gear sets 18, 20.

[0012] A first clutch 24 selectively connects the first node 16A of the second planetary gear set 16 and the input member or input shaft 12 to the first node 18A of the combined levers of the third and fourth planetary gear sets 18, 20. A second clutch 26 selectively connects the first node 16A of the second planetary gear set 16 and the input member or input shaft 12 to the third node 18B, 20B of the combined levers of the third and fourth planetary gear sets 18, 20 and the third node 16C of the second planetary gear set 16. A third clutch 28 selectively connects the third node 18B, 20B of the combined levers of the third and fourth planetary gear sets 18, 20 to the first node 20A of the fourth planetary gear set 20. A first brake 30 connects the first node 18A of the combined levers of the third and fourth planetary gear sets 18, 20. selectively with a gearbox housing 50.A second brake 32 selectively connects the second node 20A of the combined levers of the third and fourth planetary gear sets 18, 20 to the transmission housing 50. A third brake or selectable one-way clutch (SOWC) 34 selectively connects the third node 18B, 20B of the combined levers of the third and fourth planetary gear sets 18, 20 and the third node 16C of the second planetary gear set 16 to the transmission housing 50. A fourth brake 36 selectively connects the third node 14C of the first planetary gear set 14 to the transmission housing 50.

[0013] Fig. Figure 2 schematically illustrates the nine-speed transmission 10 according to the present invention. In Fig. 2 the numbering is taken from the lever diagram of Fig. 1. The clutches and coupling devices are shown accordingly, whereas the nodes of the planetary gear sets now appear as components of planetary gear sets, such as sun gears, ring gears, planet gears and carrier elements.

[0014] The planetary gear set 14 includes a sun gear member 14C, a ring gear member 14A, and a carrier member 14B that rotatably supports a set of planet gears 14D (only one of which is shown). The sun gear member 14C is connected for common rotation with a first shaft or interconnecting member 42. The ring gear member 14A is connected for common rotation with a second shaft or interconnecting member 44. The carrier member 14B is connected for common rotation with a third shaft or interconnecting member 46 and the output shaft or member 22. The planet gears 14D are each configured to mesh with both the sun gear member 14C and the ring gear member 14A.

[0015] The planetary gear set 16 includes a sun gear 16A, a ring gear 16C, and a carrier member 16B that rotatably supports a set of planet gears 16D (only one of which is shown). The sun gear 16A is connected for common rotation with the input shaft or member 12. The ring gear 16C is connected for common rotation with a fourth shaft or interconnecting member 48. The carrier member 16B is connected for common rotation with the second shaft or interconnecting member 44. The planet gears 16D are each configured to mesh with both the sun gear 16A and the ring gear 16C.

[0016] The planetary gear set 18 includes a sun gear 18A, a ring gear 18C, and a carrier member 18B that rotatably supports a set of stepped planet gears 18D (only one of which is shown). The stepped pinions 18D each have two portions of different diameters, each portion corresponding to one of the gear sets 18 and 20, respectively. The sun gear 18A is connected for common rotation with a fifth shaft or interconnecting member 52. The ring gear 18C is connected for common rotation with the third shaft or interconnecting member 46. The carrier member 18B is connected for common rotation with the fourth shaft or interconnecting member 48 and a sixth shaft or interconnecting member 54. The stepped planetary gears 18D are each configured to mesh with both the sun gear 18A and the ring gear 18C and with the planetary gear set 20, as described below.

[0017] The planetary gear set 20 includes a sun gear member 20A and a carrier member 20B that rotatably supports a set of stepped planet gears 18D (only one of which is shown). The sun gear member 20A is connected for common rotation with a seventh shaft or interconnecting member 56. The carrier member 20B is connected for common rotation with the sixth shaft or interconnecting member 54 and with an eighth shaft or interconnecting member 58. The stepped planet gears 18D are each configured to mesh with the sun gear member 20A. The planetary gear set 20 does not include a separate ring gear, thereby reducing the cost and package requirements of the planetary gear set.

[0018] The torque-transmitting mechanisms or clutches 24, 26, 28 and brakes 30, 32, 34, and 36 provide selective connection of the shafts or interconnecting members, the members of the planetary gear sets, and the housing. The clutches 24, 26, 28 and brakes 30, 32, and 36 are friction, dog, or synchronizer-type mechanisms, or the like, while the brake 34 may be a SWOC. For example, the first clutch 24 is selectively engageable to connect the input shaft or member 12 to the fifth shaft or interconnecting member 52. The second clutch 26 is selectively engageable to connect the input shaft or member 12 to the fourth shaft or interconnecting member 48. The third clutch 28 is selectively engageable to connect the seventh shaft or interconnecting member 56 to the eighth shaft or interconnecting member 58.The first brake 30 is selectively engageable to connect the fifth shaft or interconnecting member 52 to the transmission housing 50, thereby limiting rotation of the member 52 relative to the transmission housing 50. The second brake 32 is selectively engageable to connect the seventh shaft or interconnecting member 56 to the transmission housing 50, thereby limiting rotation of the member 56 relative to the transmission housing 50. The third brake or SWOC 34 is selectively engageable to connect the eighth shaft or interconnecting member 58 to the transmission housing 50, thereby limiting rotation of the member 58 relative to the transmission housing 50. The fourth brake 36 is selectively engageable to connect the first shaft or interconnecting member 42 to the transmission housing 50, thereby limiting rotation of the member 42 relative to the transmission housing 50.

[0019] The SWOC 34 generally includes a one-way clutch mechanism 70 and a locking mechanism 72. The clutch mechanism 70 generally includes an input 74 connected to the transmission housing 50 and an output 76 connected to the eighth shaft or interconnecting member 58. The clutch mechanism 70 may be any type of one-way clutch, including, but not limited to, roller, pawl, expander, mechanical diode, and rocker clutches. The locking mechanism 72 selectively locks and unlocks the clutch mechanism 70 and may include rocker, diode, strut, or dog clutch-type locking mechanisms.

[0020] When the SOWC 34 is unlocked, the SOWC 34 operates similarly to a traditional one-way clutch, where the output 76 is free to rotate relative to the input 74 in a first rotational direction, but is not free to rotate relative to the input 74 in a second, opposite rotational direction. When the locking mechanism 72 is engaged, or locked, the output 76 is unable to rotate relative to the input 74 in either rotational direction. It should be noted that the SOWC 34 may include up to four operating modes. For example, the SOWC 34 may also include an open position. In the open position, the locking mechanism 72 unlocks the output 76 from the input 74 in either rotational direction.The SOWC 34 may also include a further unlocked position in which the SOWC 34 allows the output 76 to rotate freely relative to the input 74 in the second rotational direction, but does not allow the output 76 to rotate freely relative to the input 74 in the first rotational direction.

[0021] The input shaft or member 12 is continuously connected to a torque converter, such as the starting device 80, and the output shaft or member 22 is continuously connected to an output transfer mechanism 90. The starting device 80 includes a torus 82 contained within a housing 81 coupled to the transmission housing 50. The torus 82 is connected to a stator by a one-way clutch 84, which ensures that the torus rotates in only one direction. The torus 82 is also connected to the motor vehicle's engine by a shaft or member 85. The starting device 80 further includes a dual spring / damper assembly 86 having two springs / dampers 86A and 86B. The spring / damper assembly 86 is selectively coupled to the torus 82 by means of a clutch 87 to minimize vibration transmission to the transmission 10.Further, torque is transferred from the engine to the transmission 10 when the clutch 87 is engaged. In other implementations, the starting device 80 may include a fluid coupling subject to a slip action and optionally provided with a lock-up clutch, a wet or dry type friction clutch, or a P2 electric motor device.

[0022] Now, with reference to Fig. 2 and Fig. 3 describes the operation of the nine-speed transmission 10. It should be noted that the transmission 10 is capable of transmitting torque from the input shaft or member 12 to the output shaft or member 22 in nine forward speed or torque ratios and one reverse speed or torque ratio. Each forward and reverse speed or torque ratio is achieved by engaging two of the torque-transmitting mechanisms (i.e., first clutch 24, second clutch 26, third clutch 28, first brake 30, second brake 32, third brake 34, and fourth brake 36), as explained below. Fig. Figure 3 is a shift chart illustrating the various combinations of torque-transmitting mechanisms that are activated or engaged to achieve the various gear states. An "X" within the box means that the particular clutch or brake mentioned is engaged to achieve the desired gear state. An "O" represents that the particular torque-transmitting device (i.e., a brake or clutch) is on or active, but is not carrying torque. Actual numerical gear ratios of the various gear states are also illustrated, although it should be noted that these numerical values ​​are exemplary only and that they can be adjusted over considerable ranges to accommodate various applications and operating criteria of the transmission 10.Of course, other gear ratios are achievable depending on the selected gear diameter, the selected gear tooth count and the selected gear configuration.

[0023] In Fig. 3, a shift chart is shown illustrating an engagement state of the various torque-transmitting mechanisms in each of the available forward and reverse gears or ratios of the transmission 10. Accordingly, a reverse gear is established by the engagement or activation of the first clutch 24 and the SWOC 34. The first clutch 24 connects the input shaft or member 12 to the fifth shaft or interconnecting member 52. The third brake 34 connects the eighth shaft or interconnecting member 58 to the transmission housing 50 to restrict rotation of the member 58 relative to the transmission housing 50. Likewise, the nine forward gear ratios are achieved by varying combinations of clutch and brake engagement, as shown in Fig. 3 is shown.

[0024] Fig. 4, the transmission 10 includes an engine start / stop enable system 100 that includes a detent mechanism 102 associated with the third brake or SOWC 34. The detent mechanism 102 may be any suitable mechanism that places the respective clutch or brake, such as, for example, those described below, in a ready state. The ready state refers to various states or conditions of the clutch or brake, which may include a filled state in which oil is fed into the circuits that actuate the clutch, a piloted state in which the clutch has been moved near full engagement, and an engaged state in which the clutch is fully engaged and ready to transmit torque, or any other state in between.The transmission also includes a hydraulic control system 104 having a first solenoid valve 106, a second solenoid valve 108, a third solenoid valve 110, a fourth solenoid valve 112, a fifth solenoid valve 114, a sixth solenoid valve 116, and a seventh solenoid valve 118. In one embodiment, solenoid valves 106, 108, 110, 112, 114, 116, and 118 are variable force solenoid valves. In the particular embodiment shown in FIG. Fig.4, the first solenoid valve 106 is in selective fluid communication with the first clutch 24. The second solenoid valve 108 is in selective fluid communication with the second clutch 26. The third solenoid valve 110 is in selective fluid communication with the third clutch 28. The fourth solenoid valve 112 is in selective fluid communication with the first brake 30. The fifth solenoid valve 114 is in selective fluid communication with the second brake 32. The sixth solenoid valve 116 is in selective fluid communication with the third brake 34. The seventh solenoid valve 118 is in selective fluid communication with the fourth brake 36.

[0025] It should be appreciated that the hydraulic control system 104 may include various other systems, modules, solenoid valves, etc., without departing from the scope of the present invention. For example, in various arrangements, the hydraulic control system 104 includes variable-drain solenoid valves or on / off devices, or any other suitable devices for selectively engaging the torque-transmitting mechanisms 24, 26, 28, 30, 32, 34, and 36 by selectively communicating hydraulic fluid to the various torque-transmitting mechanisms.

[0026] Solenoid valves 106, 108, 110, 112, 114, 116, and 118 are supplied with pressurized hydraulic fluid by a pressure control subsystem 119, which includes an engine-driven pump 120 and / or an accumulator 122. Engine-driven pump 120 communicates with solenoid valves 106, 108, 110, 112, 114, 116, and 118. Alternatively, transmission 10 may include a second, auxiliary pump 124 in communication with solenoid valves 106, 108, 110, 112, 114, 116, and 118. The pressure control subsystem 119, which includes the pump 120 and the accumulator 122, as well as the solenoid valves 106, 108, 110, 112, 114, 116, and 118, receives instructions from a controller 126. The controller 126 may be a transmission control module (TCM), an engine control module (ECM), a hybrid control module, or any other type of controller.Controller 126 is preferably an electronic control device comprising a preprogrammed digital computer or processor, control logic, memory used to store data, and at least one I / O peripheral. The control logic includes a plurality of logic routines for monitoring, manipulating, and generating data.

[0027] If the motor vehicle comes to a stop while the ignition key is in the ON state, an auto-stop event may occur, in which the engine is automatically shut down. An auto-start event is then commanded based on certain indicators, such as accelerator pedal position.

[0028] During auto-start, when the engine is restarted and the motor vehicle begins moving, the motor vehicle typically restarts in first gear or reverse. That is, torque-transmitting mechanisms 24 and 34 are engaged for reverse; or torque-transmitting mechanisms 34 and 36 are engaged for first gear. However, during auto-stop, main pump 80 no longer supplies pressure to the clutches and brakes. Accordingly, when the motor vehicle is ready to restart and lock-out mechanism 102 is not engaged, transmission pump 120 is generally required to pump sufficient pressure to two of the torque-transmitting mechanisms depending on the gear that has been commanded. Sufficient pressure is preferably supplied such that the torque-transmitting mechanisms can be quickly engaged without delay when the vehicle restarts.Likewise, accumulator 122 is sized to supply sufficient fluid volume and flow, as moderated by respective solenoid valves 106, 108, 110, 112, 114, 116, and 118, to the torque-transmitting mechanisms depending on which gear has been commanded. Accumulator 122 supplies system pressure when the pump restarts and builds pressure. Alternatively, auxiliary pump 124 may be used in place of accumulator 122 to supply the appropriate hydraulic fluid pressure to the devices in hydraulic control system 104 and thus selectively engage torque-transmitting mechanisms 24, 26, 30, 32, 34, and 36. In some arrangements, a combination of two or all of transmission pump 120, accumulator 122, and auxiliary pump 124 provides flow to the torque-transmitting mechanisms.

[0029] With the implementation of the automatic start / stop enable system 100, the brake 34 can be considered a holding brake. That is, prior to or upon a start event, the detent mechanism 102 is activated to position the brake 34 in standby. Therefore, only the transmission pump 120, the accumulator 122, or the auxiliary pump 124 need provide sufficient pressure or volume of hydraulic fluid to engage one of the remaining torque-transmitting mechanisms 24 and 36 for first gear or reverse.Thus, when using the locking mechanism 102, the transmission pump 120 or the accumulator 122 or the auxiliary pump 124 is required to provide pressure or fluid volume to one torque-transmitting mechanism for a start event, whereas without the locking mechanism 102, the transmission pump 120 or the accumulator 122 or the auxiliary pump 124 is required to provide pressure or fluid volume to two torque-transmitting mechanisms for a start event.

[0030] The locking mechanism 102 is directly coupled to the third brake 34 and may be a mechanical lock or a hydraulic lock or any other suitable mechanism that may be under the control of the controller 126.

Claims

[1] Transmission (10) in a motor vehicle with a prime mover, the transmission (10) comprising: a gear housing (50); an input element (12); an output element (22); a first, second, third and fourth planetary gear set (14, 16, 18, 20), each comprising a sun gear (14C, 16A, 18A, 20A), a carrier element (14B, 16B, 18B, 20A) and, apart from the fourth planetary gear set (20), a ring gear (14A, 16C, 18C); wherein the output member (22) is continuously connected to the carrier element (14B) of the first planetary gear set (14) and the ring gear (18C) of the third planetary gear set (18), a connecting element (44) continuously connecting the ring gear (14A) of the first planetary gear set (14) to the carrier element (16B) of the second planetary gear set (16); a first torque-transmitting mechanism (24) selectively engageable to interconnect the input member (12) and the sun gear member (16A) of the second planetary gear set (16) with the sun gear member (18A) of the third planetary gear set (18); a second torque-transmitting mechanism (26) selectively engageable to interconnect the input member (12) and the sun gear member (16A) of the second planetary gear set (16) with the ring gear member (16C) of the second planetary gear set (16), the carrier member (18B) of the third planetary gear set (18), and the carrier member (20B) of the fourth planetary gear set (20); a third torque-transmitting mechanism (28) selectively engageable to interconnect the sun gear member (20A) of the fourth planetary gear set (20) with the ring gear member (16C) of the second planetary gear set (16), the carrier member (18B) of the third planetary gear set (18), and the carrier member (20B) of the fourth planetary gear set (20); a fourth torque-transmitting mechanism (30) selectively engageable to interconnect the sun gear (18A) of the third planetary gear set (18) with the transmission housing (50); a fifth torque-transmitting mechanism (32) selectively engageable to interconnect the sun gear member (20A) of the fourth planetary gear set (20) with the transmission housing (50); a sixth torque-transmitting mechanism (34) selectively engageable to interconnect the ring gear member (16C) of the second planetary gear set (16), the carrier member (18B) of the third planetary gear set (18), and the carrier member (20B) of the fourth planetary gear set (20) with the transmission housing (50); a seventh torque-transmitting mechanism (36) selectively engageable to interconnect the sun gear (14C) of the first planetary gear set (14) with the transmission housing (50); and a locking mechanism (102) connected to the sixth torque-transmitting mechanism (34), the locking mechanism (102) locking the sixth torque-transmitting mechanism (34) in a standby state, wherein standby state refers to states of the sixth torque-transmitting mechanism (34) including a filled state in which oil is fed into the circuits that actuate the sixth torque-transmitting mechanism (34), a piloted state in which the sixth torque-transmitting mechanism (34) has been moved near full engagement, and an engaged state in which the sixth torque-transmitting mechanism (34) is fully engaged and ready to transmit torque, or any other state in between, and wherein the seven torque-transmitting mechanisms (24, 26, 28, 3, 32, 34, 36) are selectively engageable in combinations of two to establish nine forward speed ratios and one reverse speed ratio between the input member (12) and the output member (22), wherein the sixth torque transmitting mechanism (34) is in the standby state during the first forward speed ratio and the reverse speed ratio, wherein the locking mechanism (102) locks the sixth torque transmitting mechanism (34) in preparation for a stop event of the motor vehicle's engine.

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