Multiple speed transmission with a pump assisted launch device

This application claims the benefit of U.S. Provisional Application No. 61/432,182, filed Jan. 12, 2011. The entire contents of the above application are incorporated herein by reference.

The invention relates generally to a powertrain having a pump assisted launch device coupled to a multiple speed transmission, and more particularly to a powertrain having an engine connected to a rotating housing of a pump and a transmission a rotor of the pump.

The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.

A typical multiple speed transmission uses a combination of friction clutches or brakes, planetary gear arrangements and fixed interconnections to achieve a plurality of gear ratios. The number and physical arrangement of the planetary gear sets, generally, are dictated by packaging, cost and desired speed ratios.

While current transmissions achieve their intended purpose, the need for new and improved transmission configurations which exhibit improved performance, especially from the standpoints of efficiency, responsiveness and smoothness and improved packaging, primarily reduced size and weight, is essentially constant. Accordingly, there is a need for an improved, cost-effective, compact multiple speed transmission.

A powertrain is provided having an engine and a launch device that supplies a driving torque to a transmission which supplies various gear or speed ratios to a final drive unit. In one embodiment, the launch device includes a positive displacement pump coupled with a gear set. The positive displacement pump is preferably a high efficiency pump that acts as a reaction element through the gear set during vehicle launch. In another embodiment, the launch device includes a pump having a rotatable housing connected to the engine and a rotor connected to the transmission.

Further features, aspects and advantages of the present invention will become apparent by reference to the following description and appended drawings wherein like reference numbers refer to the same component, element or feature.

The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

FIG. 1 is a lever diagram of an embodiment of a nine speed transmission according to the present invention;

FIG. 2 is a stick diagram of an embodiment of a nine speed transmission according to the present invention;

FIG. 3 is a truth table presenting the state of engagement of the various torque transmitting elements in each of the available forward and reverse speeds or gear ratios of the transmission illustrated in FIGS. 1 and 2 ;

FIG. 4 is a schematic diagram of a powertrain employing the transmissions of FIGS. 1-3 incorporated with a launch device according to the principles of the present invention; and

FIG. 5 is a schematic diagram of another powertrain employing the transmissions of FIGS. 1-3 incorporated with a launch device according to the principles of the present invention.

The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.

Referring to FIG. 1 , an embodiment of a nine speed transmission 200 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 wherein the three basic mechanical components of the planetary gear set are each represented by a node. Therefore, a single lever contains three nodes: one for the sun gear, one for the planet gear carrier, and one for the ring gear. The relative length between the nodes of each lever can be used to represent the ring-to-sun ratio of each respective gear set. These lever ratios, in turn, are used to vary the gear ratios of the transmission in order to achieve appropriate ratios and ratio progression. Mechanical couplings or interconnections between the nodes of the various planetary gear sets are illustrated by thin, horizontal lines and torque transmitting devices such as clutches and brakes are presented as interleaved fingers. If the device is a brake, one set of the fingers is grounded. Further explanation of the format, purpose and use of lever diagrams can be found in SAE Paper 810102, “The Lever Analogy: A New Tool in Transmission Analysis” by Benford and Leising which is hereby fully incorporated by reference.

The transmission 200 includes an input shaft or member 212 , a first planetary gear set 214 having three nodes: a first node 214 A, a second node 214 B and a third node 214 C, a second planetary gear set 216 having three nodes: a first node 216 A, a second node 216 B and a third node 216 C, a third planetary gear set 218 having three nodes: a first node 218 A, a second node 218 B and a third node 218 C, a fourth planetary gear set 220 having three nodes: a first node 220 A, a second node 220 B and a third node 220 C and an output shaft or member 222 .

The input member 212 is coupled to a launch device 225 and the first node 216 A of the second planetary gear set 216 . The output member 222 is coupled to the second node 218 B of the third planetary gear set 218 and the second node 220 B of the fourth planetary gear set 220 . The second node 214 B of the first planetary gear set 214 is coupled to the second node 216 B of the second planetary gear set 216 . The third node 214 C of the first planetary gear set 214 is coupled to the third node 216 C of the second planetary gear set 216 and the first node 218 A of the third planetary gear set 218 . The second node 218 B of the third planetary gear set 218 is coupled to the second node 220 B of the fourth planetary gear set 220 . The third node 218 C of the third planetary gear set 18 is coupled to the third node 220 C of the fourth planetary gear set 220 .

A first clutch 226 selectively connects the first node 216 A of the second planetary gear set 216 and the input member 212 with the third node 218 C of the third planetary gear set 218 and the third node 220 C of the fourth planetary gear set 220 . A second clutch 228 selectively connects the first node 216 A of the second planetary gear set 216 and the input member 212 with the first node 220 A of the fourth planetary gear set 220 . A first brake 230 selectively connects the first node 214 A of the first planetary gear set 214 to a stationary member or a transmission housing 240 . A second brake 232 selectively connects the second node 214 B of the first planetary gear set 214 and the second node 2168 of the second planetary gear set 216 to a stationary member or transmission housing 240 . A third brake 234 selectively connects the third node 214 C of the first planetary gear set, the third node 216 C of the second planetary gear set 216 , and the first node 218 A of the third planetary gear set 218 to the stationary member or transmission housing 240 . A fourth brake 236 selectively connects the third node 218 C of the third planetary gear set 218 and the third node 220 C of the fourth planetary gear set 220 to the stationary member or transmission housing 240 .

Referring now to FIG. 2 , a stick diagram presents a schematic layout of an embodiment of the nine speed transmission 200 according to the present invention. In FIG. 2 , the numbering from the lever diagram of FIG. 1 is carried over. The clutches, brakes, and couplings are correspondingly presented 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 planet gear carriers.

For example, the first planetary gear set 214 includes a sun gear member 214 A, a planet gear carrier member 214 C and a ring gear member 214 B. The sun gear member 214 A is connected for common rotation with a first shaft or interconnecting member 242 . The ring gear member 214 B is connected for common rotation with a second shaft or interconnecting member 244 . The planet gear carrier member 214 C rotatably supports a set of planet gears 214 D (only one of which is shown) and is connected for common rotation with a third shaft or interconnecting member 246 and a fourth shaft or interconnecting member 248 . The planet gears 214 D are each configured to intermesh with both the sun gear member 214 A and the ring gear member 214 B.

The second planetary gear set 216 includes a sun gear member 216 A, a planet carrier member 216 C that rotatably supports a set of planet gears 216 D and 216 E, and a ring gear member 216 B. The sun gear member 216 A is connected for common rotation with the input member 212 . The ring gear member 216 B is connected for common rotation with the second shaft or interconnecting member 244 . The planet carrier member 216 C is connected for common rotation with the fourth shaft or interconnecting member 248 and a fifth shaft or interconnecting member 250 . The planet gears 216 D are each configured to intermesh with both the ring gear member 216 B and the planet gears 216 E. The planet gears 216 E are each configured to intermesh with both the planet gears 216 D and the sun gear 216 A.

The third planetary gear set 218 includes a sun gear member 218 A, a ring gear member 218 B and a planet carrier member 218 C that rotatably supports a set of planet gears 218 D. The sun gear member 218 A is connected for common rotation with the fifth interconnecting member 250 . The ring gear member 218 B is connected for common rotation with a sixth shaft or interconnecting member 252 . The planet carrier member 218 C is connected for common rotation with a seventh shaft or interconnecting member 254 and with an eighth shaft or interconnecting member 256 . The planet gears 218 D are each configured to intermesh with both the sun gear member 218 A and the ring gear member 218 B.

The fourth planetary gear set 220 includes a sun gear member 220 A, a ring gear member 220 C and a planet carrier member 220 B that rotatably supports a set of planet gears 220 D. The sun gear member 220 A is connected for common rotation with a ninth shaft or interconnecting member 258 . The ring gear member 220 C is connected for common rotation with the seventh interconnecting member 254 . The planet carrier member 220 B is connected for common rotation with the sixth interconnecting member 252 and with the output member 222 . The planet gears 220 D are each configured to intermesh with both the sun gear member 220 A and the ring gear member 220 C.

The input shaft or member 212 is connected to the launch device 225 . The output shaft or member 222 is preferably continuously connected with a final drive unit or transfer case (not shown).

The torque-transmitting mechanisms or clutches 226 , 228 and brakes 230 , 232 , 234 , 236 allow for selective interconnection of the shafts or interconnecting members, members of the planetary gear sets and the housing. For example, the first clutch 226 is selectively engageable to connect the eighth interconnecting member 256 with the input member 212 . The second clutch 228 is selectively engageable to connect the ninth interconnecting member 258 with the input member 212 . The first brake 230 is selectively engageable to connect the first interconnecting member 242 to the stationary member or transmission housing 240 in order to restrict the sun gear member 214 A of the first planetary gear set 214 from rotating relative to the stationary member or transmission housing 240 . The second brake 232 is selectively engageable to connect the second interconnecting member 244 to the stationary member or transmission housing 240 in order to restrict the ring gear member 214 B of the first planetary gear set 214 and the ring gear member 216 B of the second planetary gear set 216 from rotating relative to the stationary member or transmission housing 240 . The third brake 234 is selectively engageable to connect the third interconnecting member 246 to the stationary member or transmission housing 240 in order to restrict the planet carrier member 214 C of the first planetary gear set 214 , the planet carrier member 216 C of the second planetary gear set 216 , and the sun gear 218 A of the third planetary gear set 218 from rotating relative to the stationary member or transmission housing 240 . The fourth brake 236 is selectively engageable to connect the seventh interconnecting member 254 to the stationary member or transmission housing 240 in order to restrict the planet carrier member 218 C of the third planetary gear set 218 and the ring gear member 220 C of the fourth planetary gear set 220 from rotating relative to the stationary element or transmission housing 240 .

Referring now to FIGS. 2 and 3 , the operation of the embodiment of the nine speed transmission 200 will be described. It will be appreciated that the transmission 200 is capable of transmitting torque from the input shaft or member 212 to the output shaft or member 222 in at least nine forward speed or torque ratios and at least one reverse speed or torque ratio. Each forward and reverse speed or torque ratio is attained by engagement of one or more of the torque-transmitting mechanisms (i.e. first clutch 226 , second clutch 228 , first brake 230 , second brake 232 , third brake 234 , and fourth brake 236 ), as will be explained below. FIG. 3 is a truth table presenting the various combinations of torque transmitting mechanisms that are activated or engaged to achieve the various gear states. Actual numerical gear ratios of the various gear states are also presented although it should be appreciated that these numerical values are exemplary only and that they may be adjusted over significant ranges to accommodate various applications and operational criteria of the transmission 200 . An example of the gear ratios that may be obtained using the embodiments of the present invention are also shown in FIG. 3 . Of course, other gear ratios are achievable depending on the gear diameter, gear teeth count and gear configuration selected.

To establish reverse gear, the first brake 230 and the fourth brake 236 are engaged or activated. The first brake 230 connects the first interconnecting member 242 to the stationary member or transmission housing 240 in order to restrict the sun gear member 214 A of the first planetary gear set 214 from rotating relative to the stationary member or transmission housing 240 . The fourth brake 236 connects the seventh interconnecting member 254 to the stationary member or transmission housing 240 in order to restrict the planet carrier member 218 C of the third planetary gear set 218 and the ring gear member 220 C of the fourth planetary gear set 220 from rotating relative to the stationary element or transmission housing 240 . Likewise, the nine forward ratios are achieved through different combinations of clutch and brake engagement, as shown in FIG. 3 .

Referring to FIG. 4 , a schematic diagram of a powertrain for a motor vehicle is indicated by reference number 300 . The powertrain 300 includes an engine 302 coupled with the launch device 225 that supplies a driving torque to the transmission 200 , described above, which supplies various gear or speed ratios to a final drive unit 304 . The engine 302 may be a conventional internal combustion engine or an electric engine, or any other type of prime mover, without departing from the scope of the present disclosure. The engine 302 supplies a driving torque to the launch device 225 through an engine output shaft 306 .

The launch device 225 includes a positive displacement pump 308 having a rotatable housing 310 and a rotor 312 . The rotatable housing 310 is coupled to the engine output shaft 306 and the rotor 312 is coupled to the transmission input shaft 212 . The pump 308 is preferably located on axis with the engine output shaft 306 and therefore receives no multiplication of engine torque or engine speed. Instead the pump 308 uses the static pressure of the hydraulic fluid within the pump 308 times the displacement of the pump 308 (e.g. area of a vane or a piston) for producing hydraulic torque. The pump 308 preferably operates at a high efficiency and high pressure (e.g. 1500 to 5000 psi) at close to zero speed. Therefore, the pump 308 is preferably a radial or axial piston pump.

During launch of the powertrain 300 there is relative speed between the engine output shaft 306 and the transmission input shaft 212 . Therefore, there is relative speed between the pump housing 310 and the pump rotor 312 which pumps hydraulic fluid from an inlet 314 of the pump 308 to an outlet 316 of the pump 308 . The inlet 314 is connected to a sump 320 . The outlet 316 is connected to an accumulator 322 and a valve body 324 through a flow control valve 318 . When pressure of the hydraulic fluid builds up due to flow restriction, the hydraulic fluid starts transmitting torque from the rotating housing 310 to the stationary rotor 312 and the powertrain 300 begins to launch. Flow restriction of the hydraulic fluid may be controlled by operating the valve 318 . Alternatively, the pump 308 may be operated through regenerative braking wherein the transmission input shaft 212 provides the driving torque to the pump 308 . When the pump 308 reaches a coupling speed, the speed of the transmission input shaft 212 equals the speed of the engine output shaft 306 and therefore the pump 308 ceases to pump the hydraulic fluid.

During launch, the hydraulic fluid may be directed into the accumulator 322 to provide potential energy storage and/or to the valve body 324 to provide pressurized hydraulic fluid to the control systems of the transmission 200 . In addition, the hydraulic fluid from the outlet 316 may be diverted through a valve 326 back to the inlet 314 to provide additional inlet oil flow.

Turning to FIG. 5 , a schematic diagram of another example of a powertrain for a motor vehicle is indicated by reference number 400 . The powertrain 400 includes an engine 402 and the launch device 225 that supplies a driving torque to the transmission 200 , described above, which supplies various gear or speed ratios to a final drive unit 406 . The engine 402 may be a conventional internal combustion engine or an electric engine, or any other type of prime mover, without departing from the scope of the present disclosure. The engine 402 supplies a driving torque to the launch device 225 through an engine output shaft 403 . The launch device 225 includes a positive displacement pump 408 having a rotor 409 coupled with a gear set 410 . For example, the gear set 410 may be a planetary gear set having a sun gear 410 A, a ring gear 410 B, and a carrier member 410 C. In one example, the rotor 409 of the pump 408 is connected to the sun gear 410 A, the transmission input member 212 is connected to the carrier member 410 C, and the engine output member 403 is connected to the ring gear 410 B. The positive displacement pump 408 is preferably a high efficiency pump that acts as a reaction element through the gear set 410 during vehicle launch. Additionally the pump 408 is driven by the engine 402 through the gear set 410 . In another example, a one-way clutch is disposed between the pump 408 and the launch gear set 410 to allow engine braking during coasting.

The description of the invention is merely exemplary in nature and variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.