Multi-speed transmission having three planetary gear sets

A transmission is provided having an input member, an output member, three planetary gear sets, a plurality of coupling members and a plurality of torque transmitting devices. Each of the planetary gear sets includes first, second and third members. The torque transmitting devices include clutches and brakes.

FIELD

The invention relates generally to a multiple speed transmission having a plurality of planetary gear sets and a plurality of torque transmitting devices and more particularly to a transmission having six or more speeds, three planetary gear sets and a plurality of torque transmitting devices.

BACKGROUND

A typical multiple speed transmission uses a combination of friction clutches, 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.

SUMMARY

A transmission is provided having an input member, an output member, three planetary gear sets, a plurality of coupling members and a plurality of torque transmitting devices. Each of the planetary gear sets includes first, second and third members. The torque transmitting devices are for example clutches and brakes.

In one embodiment, a transmission includes an input member, an output member, first, second and third planetary gear sets each having first, second and third members, a first interconnecting member continuously interconnecting the third member of the first planetary gear set with a stationary member, a second interconnecting member continuously interconnecting the second member of the second planetary gear set with the third member of the third planetary gear set, and a third interconnecting member continuously interconnecting the first member of the second planetary gear set with the first member of the third planetary gear set. A first torque transmitting mechanism is selectively engageable to interconnect the second member of the first planetary gear set and the input member with the third member of the second planetary gear set, a second torque transmitting mechanism is selectively engageable to interconnect the second member of the first planetary gear set and the input member with the first member of the second planetary gear set, a third torque transmitting mechanism is selectively engageable to interconnect the first member of the first planetary gear set with the first member of the second planetary gear set and the first member of the third planetary gear set, a fourth torque transmitting mechanism is selectively engageable to interconnect the third member of the second planetary gear set with the stationary member and a fifth torque transmitting mechanism is selectively engageable to interconnect the second member of the second planetary gear set and the third member of the third planetary gear set with the stationary member. The torque transmitting mechanisms are selectively engageable in combinations of at least two to establish at least six forward speed ratios and at least one reverse speed ratio between the input member and the output member.

In another embodiment, a transmission includes an input member, an output member, first, second and third planetary gear sets each having first, second and third members, a first interconnecting member continuously interconnecting the first member of the first planetary gear set with a stationary member, a second interconnecting member continuously interconnecting the second member of the second planetary gear set with the third member of the third planetary gear set, and a third interconnecting member continuously interconnecting the first member of the second planetary gear set with the second member of the third planetary gear set. A first torque transmitting mechanism is selectively engageable to interconnect the second member of the first planetary gear set with the third member of the second planetary gear set, a second torque transmitting mechanism is selectively engageable to interconnect the third member of the first planetary gear set and the input member with the second member of the second planetary gear set and the third member of the third planetary gear set, a third torque transmitting mechanism is selectively engageable to interconnect the second member of the first planetary gear set with the first member of the third planetary gear set, a fourth torque transmitting mechanism is selectively engageable to interconnect the third member of the second planetary gear set with the stationary member and a fifth torque transmitting mechanism is selectively engageable to interconnect the second member of the second planetary gear set and the third member of the third planetary gear set with the stationary member. The torque transmitting mechanisms are selectively engageable in combinations of at least two to establish at least six forward speed ratios and at least one reverse speed ratio between the input member and the output member.

In another embodiment, a transmission includes an input member, an output member, first, second and third planetary gear sets each having first, second and third members, a first interconnecting member continuously interconnecting the third member of the first planetary gear set with a stationary member, a second interconnecting member continuously interconnecting the second member of the second planetary gear set with the second member of the third planetary gear set, and a third interconnecting member continuously interconnecting the third member of the second planetary gear set with the third member of the third planetary gear set. A first torque transmitting mechanism is selectively engageable to interconnect the second member of the first planetary gear set and the input member with the third member of the second planetary gear set and the third member of the third planetary gear set, a second torque transmitting mechanism is selectively engageable to interconnect the second member of the first planetary gear set and the input member with the first member of the second planetary gear set, a third torque transmitting mechanism is selectively engageable to interconnect the first member of the first planetary gear set with the first member of the second planetary gear set, a fourth torque transmitting mechanism is selectively engageable to interconnect the third member of the second planetary gear set and the third member of the third planetary gear set with the stationary member, and a fifth torque transmitting mechanism is selectively engageable to interconnect the second member of the second planetary gear set and the second member of the third planetary gear set with the stationary member. The torque transmitting mechanisms are selectively engageable in combinations of at least two to establish at least six forward speed ratios and at least one reverse speed ratio between the input member and the output member.

In another embodiment, a transmission includes an input member, an output member, first, second and third planetary gear sets each having first, second and third members, a first interconnecting member continuously interconnecting the third member of the third planetary gear set with a stationary member, a second interconnecting member continuously interconnecting the second member of the first planetary gear set with the second member of the second planetary gear set, and a third interconnecting member continuously interconnecting the third member of the first planetary gear set with the third member of the second planetary gear set. A first torque transmitting mechanism is selectively engageable to interconnect the first member of the third planetary gear set and the input member with the third member of the second planetary gear set and the third member of the first planetary gear set, a second torque transmitting mechanism is selectively engageable to interconnect the second member of the third planetary gear set with the first member of the second planetary gear set, a third torque transmitting mechanism is selectively engageable to interconnect the second member of the third planetary gear set with the first member of the first planetary gear set, a fourth torque transmitting mechanism is selectively engageable to interconnect the first member of the second planetary gear set with the stationary member and a fifth torque transmitting mechanism is selectively engageable to interconnect the third member of the second planetary gear set and the third member of the first planetary gear set with the stationary member. The torque transmitting mechanisms are selectively engageable in combinations of at least two to establish at least six forward speed ratios and at least one reverse speed ratio between the input member and the output member.

DETAILED DESCRIPTION

At the outset, it should be appreciated that the embodiments of the six speed automatic transmission of the present invention have an arrangement of permanent mechanical connections between the elements of the three planetary gear sets. A third component or element of a first planetary gear set is permanently coupled to a ground. A third component or element of a third planetary gear set is permanently coupled to a second component or element of a second planetary gear set. A second component or element of the third planetary gear set is permanently coupled to a first component or element of the second planetary gear set.

Referring now toFIG. 1, an embodiment of a six speed transmission10is 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 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. 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 interconnected through 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-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 an 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. 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 transmission10includes an input shaft or member12, a first planetary gear set14, a second planetary gear set16, a third planetary gear set18and an output shaft or member22. The first planetary gear set14has three nodes: a first node14A, a second node14B and a third node14C. The second planetary gear set16has three nodes: a first node16A, a second node16B and a third node16C. The third planetary gear set18has three nodes: a first node18A, a second node18B and a third node18C.

The input member12is continuously coupled to the second node14B of the first planetary gear set14. The output member22is coupled to the first node16A of the second planetary gear set16. The third node14C of the first planetary gear set14is coupled to a stationary member or transmission housing36. The second node16B of the second planetary gear set16is coupled to the third node18C of the third planetary gear set18. The first node16A of the second planetary gear set16is coupled to the second node18B of the third planetary gear set18.

A first clutch26selectively connects the first node14A of the first planetary gear set14with the third node16C of the second planetary gear set16. A second clutch28selectively connects the input member12and the second node14B of the first planetary gear set14with the first node18A of the third planetary gear set18. A third clutch30selectively connects the first node14A of the first planetary gear set14with the first node18A of the third planetary gear set18. A first brake32selectively connects the third node16C of the second planetary gear set16with a stationary member or transmission housing36. A second brake34selectively connects the second node16B of the second planetary gear set16with a stationary member or transmission housing36.

Referring now toFIG. 2, a stick diagram presents a schematic layout of the embodiment of the six speed transmission10according to the present invention. InFIG. 2, the numbering from the lever diagram ofFIG. 1is carried over. The clutches 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 planetary gear set14includes a sun gear member14C, a ring gear member14A and a planet gear carrier member14B that rotatably supports a set of planet gears14D (only one of which is shown). The sun gear member14C is connected to the stationary member or transmission housing36in order to prevent the sun gear member14C from rotating relative to the transmission housing36. The ring gear member14A is connected for common rotation with a first shaft or interconnecting member42. The planet carrier member14B is connected for common rotation with the input member12. The planet gears14D are each configured to intermesh with both the sun gear member14C and the ring gear member14A.

The planetary gear set16includes a sun gear member16C, a ring gear member16A and a planet gear carrier member16B that rotatably supports a set of planet gears16D (only one of which is shown). The sun gear member16C is connected for common rotation with a second shaft or interconnecting member44and with a third shaft or interconnecting member46. The ring gear member16A is connected for common rotation with the output member22. The planet carrier member16B is connected for common rotation with a fourth shaft or interconnecting member48and a fifth shaft or interconnecting member50. The planet gears16D are each configured to intermesh with both the sun gear member16C and the ring gear member16A.

The planetary gear set18includes a sun gear member18A, a ring gear member18C and a planet gear carrier member18B that rotatably supports a set of planet gears18D (only one of which is shown). The sun gear member18A is connected for common rotation with a sixth shaft or interconnecting member52a seventh shaft or interconnecting member54. The ring gear member18C is connected for common rotation with the fifth shaft or interconnecting member50. The planet carrier member18B is connected for common rotation with the output member or shaft22. The planet gears18D are each configured to intermesh with both the sun gear member18A and the ring gear member18C.

The input shaft or member12is continuously connected to an engine (not shown) or to a turbine of a torque converter (not shown). The output shaft or member22is continuously connected with the final drive unit or transfer case (not shown).

The torque-transmitting mechanisms or clutches26,28,30and brakes32and34allow for selective interconnection of the shafts or interconnecting members, members of the planetary gear sets and the housing. For example, the first clutch26is selectively engageable to connect the first shaft or interconnecting member42with the third shaft or interconnecting member46. The second clutch28is selectively engageable to connect the input member12with the seventh shaft or interconnecting member54. The third clutch30is selectively engageable to connect the first shaft or interconnecting member42with the sixth shaft or interconnecting member52. The first brake32is selectively engageable to connect the second shaft or interconnecting member44with the stationary element or the transmission housing36in order to restrict the member44from rotating relative to the transmission housing36. The second brake34is selectively engageable to connect the fourth shaft or interconnecting member48with the stationary element or the transmission housing36in order to restrict the member48from rotating relative to the transmission housing36.

Referring now toFIGS. 2 and 3, the operation of the embodiment of the six speed transmission10will be described. It will be appreciated that transmission10are capable of transmitting torque from the input shaft or member12to the output shaft or member22in at least six 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 clutch26, second clutch28, third clutch30, first brake32and second brake34), as will be explained below.FIG. 3is a truth table presenting the various combinations of torque-transmitting mechanisms that are activated or engaged to achieve the various gear states. An “X” in the box means that the particular clutch or brake 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 not carrying torque. 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 transmission10. An example of the gear ratios that may be obtained using the embodiments of the present invention are also shown inFIG. 3. Of course, other gear ratios are achievable depending on the gear diameter, gear teeth count and gear configuration selected.

To establish a reverse gear, the first clutch26and the second brake34are engaged or activated. The first clutch26connects the first shaft or interconnecting member42with the third shaft or interconnecting member46. The second brake34connects the fourth shaft or interconnecting member48with the stationary element or the transmission housing36in order to restrict the member48from rotating relative to the transmission housing36. Likewise, the six forward ratios are achieved through different combinations of clutch and brake engagement, as shown inFIG. 3.

It will be appreciated that the foregoing explanation of operation and gear states of the six speed transmission10assumes, first of all, that all the clutches not specifically referenced in a given gear state are inactive or disengaged and, second of all, that during gear shifts, i.e., changes of gear state, between at least adjacent gear states, a clutch engaged or activated in both gear states will remain engaged or activated.

Referring now toFIG. 4, another embodiment of a six speed transmission100is illustrated in a lever diagram format. The transmission100includes an input shaft or member112, a first planetary gear set114, a second planetary gear set116, a third planetary gear set118and an output shaft or member122. The first planetary gear set114has three nodes: a first node114A, a second node114B, and a third node114C. The second planetary gear set116has three nodes: a first node116A, a second node116B, and a third node116C. The third planetary gear set118has three nodes: a first node118A, a second node118B and a third node118C.

The input member112is continuously coupled to the second node114B of the first planetary gear set114. The output member122is coupled to the second node118B of the third planetary gear set118. The third node114C of the first planetary gear set114is coupled to a stationary member or a transmission housing136. The second node116B of the second planetary gear set116is coupled to the third node118C of the third planetary gear set118. The first node118A of the third planetary gear set118is coupled to the first node116A of the second planetary gear set116.

A first clutch126selectively connects the second node114B of the first planetary gear set114with the third node116C of the second planetary gear set116. A second clutch128selectively connects the second node114B of the first planetary gear set114with the first node116A of the second planetary gear set116and the first node118A of the third planetary gear set118. A third clutch130selectively connects the first node114A of the first planetary gear set114with the first node116A of the second planetary gear set116and the first node118A of the third planetary gear set118. A first brake132selectively connects the third node116C of the second planetary gear set116with a stationary member or transmission housing136. A second brake134selectively connects the third node118C of the third planetary gear set118and the second node116B of the second planetary gear set116with a stationary member or transmission housing136.

Referring now toFIG. 5, a stick diagram presents a schematic layout of the embodiment of the six speed transmission100according to the present invention. InFIG. 5, the numbering from the lever diagram ofFIG. 4is carried over. The clutches 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 planetary gear set114includes a sun gear member114C, a ring gear member114A and a planet gear carrier member114B that rotatably supports a set of planet gears114D (only one of which is shown). The sun gear member114C is connected for common rotation the stationary member or transmission housing136in order to prevent the sun gear member114C from rotating relative to the transmission housing136. The ring gear member114A is connected for common rotation with a first shaft or interconnecting member142. The planet carrier member114B is connected for common rotation with a second shaft or interconnecting member144and the input member112. The planet gears114D are each configured to intermesh with both the sun gear member114C and the ring gear member114A.

The planetary gear set116includes a sun gear member116A, a ring gear member116C and a planet gear carrier member116B that rotatably supports a set of planet gears116D (only one of which is shown). The sun gear member116A is connected for common rotation with a third shaft or interconnecting member146and a fourth shaft or interconnecting member148. The ring gear member116C is connected for common rotation with a fifth shaft or interconnecting member150. The planet carrier member116B is connected for common rotation with a sixth shaft or interconnecting member152. The planet gears116D are each configured to intermesh with both the sun gear member116A and the ring gear member116C.

The planetary gear set118includes a sun gear member118A, a ring gear member118C and a planet gear carrier member118B that rotatably supports a set of planet gears118D (only one of which is shown). The sun gear member118A is connected for common rotation with the third shaft or interconnecting member146. The ring gear member118C is connected for common rotation with the sixth shaft or interconnecting member152. The planet carrier member118B is connected for common rotation with the output member122. The planet gears118D are each configured to intermesh with both the sun gear member118A and the ring gear member118C.

The input shaft or member112is continuously connected to an engine (not shown) or to a turbine of a torque converter (not shown). The output shaft or member122is continuously connected with the final drive unit or transfer case (not shown).

The torque-transmitting mechanisms or clutches126,128, and130and brakes132and134allow for selective interconnection of the shafts or interconnecting members, members of the planetary gear sets and the housing. For example, the first clutch126is selectively engageable to connect the second shaft or interconnecting member144with the fifth shaft or interconnecting member150. The second clutch128is selectively engageable to connect the fourth shaft or interconnecting member148with the input shaft or member112. The third clutch130is selectively engageable to connect the first shaft or interconnecting member142with the fourth shaft or interconnecting member148. The first brake132is selectively engageable to connect the fifth shaft or interconnecting member150with the stationary element or the transmission housing136in order to restrict the member150from rotating relative to the transmission housing136. The second brake134is selectively engageable to connect the sixth shaft or interconnecting member152with the stationary element or the transmission housing136in order to restrict the member152from rotating relative to the transmission housing136.

Referring now toFIG. 5andFIG. 6, the operation of the embodiment of the six speed transmission100will be described. It will be appreciated that transmission100is capable of transmitting torque from the input shaft or member112to the output shaft or member122in at least six 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 clutch126, second clutch128, third clutch130, first brake132, and second brake134), as will be explained below.FIG. 6is a truth table presenting the various combinations of torque-transmitting mechanisms that are activated or engaged to achieve the various gear states. An “X” in the box means that the particular clutch or brake 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 not carrying torque. 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 transmission100. An example of the gear ratios that may be obtained using the embodiments of the present invention are also shown inFIG. 6. Of course, other gear ratios are achievable depending on the gear diameter, gear teeth count and gear configuration selected.

To establish a reverse gear, the first clutch126and the second brake134are engaged or activated. The first clutch126connects the second shaft or interconnecting member144with the fifth shaft or interconnecting member150. The second brake134connects the sixth shaft or interconnecting member152with the stationary element or the transmission housing136in order to restrict the member152from rotating relative to the transmission housing136. Likewise, the six forward ratios are achieved through different combinations of clutch and brake engagement, as shown inFIG. 6.

It will be appreciated that the foregoing explanation of operation and gear states of the six speed transmission100assumes, first of all, that all the clutches not specifically referenced in a given gear state are inactive or disengaged and, second of all, that during gear shifts, i.e., changes of gear state, between at least adjacent gear states, a clutch engaged or activated in both gear states will remain engaged or activated.

Referring now toFIG. 7, another embodiment of a six speed transmission200is illustrated in a lever diagram format. The transmission200includes an input shaft or member212, a first planetary gear set214, a second planetary gear set216, a third planetary gear set218and an output shaft or member222. The first planetary gear set214has three nodes: a first node214A, a second node214B, and a third node214C. The second planetary gear set216has three nodes: a first node216A, a second node216B, and a third node216C. The third planetary gear set218has three nodes: a first node218A, a second node218B and a third node218C.

The input member212is continuously coupled to the third node214C of the first planetary gear set214. The output member222is coupled to the second node218B of the third planetary gear set218. The second node216B of the second planetary gear set216is coupled to the third node218C of the third planetary gear set218. The first node216A of the second planetary gear set216is coupled to the second node218B of the third planetary gear set218. The first node214A of the first planetary gear set214is coupled to a stationary member or a transmission housing236.

A first clutch226selectively connects the second node214B of the first planetary gear set214with the third node216C of the second planetary gear set216. A second clutch228selectively connects the third node214C of the first planetary gear set214and the input member212with the third node218C of the third planetary gear set218and the second node216B of the second planetary gear set216. A third clutch230selectively connects the second node214B of the first planetary gear set214with the first node218A of the third planetary gear set218. A first brake232selectively connects the third node216C of the second planetary gear set216with a stationary member or transmission housing236. A second brake234selectively connects the second node216B of the second planetary gear set216and the third node218C of the third planetary gear set218with a stationary member or transmission housing236.

Referring now toFIG. 8, a stick diagram presents a schematic layout of the embodiment of the six speed transmission200according to the present invention. InFIG. 8, the numbering from the lever diagram ofFIG. 7is carried over. The clutches 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 planetary gear set214includes a sun gear member214A, a ring gear member214C and a planet gear carrier member214B that rotatably supports a set of planet gears214D (only one of which is shown). The sun gear member214A is connected for common rotation with a first shaft or interconnecting member242. The ring gear member214C is connected for common rotation with a second shaft or interconnecting member244and the input member212. The planet carrier member214B is connected for common rotation with a third shaft or interconnecting member246. The planet gears214D are each configured to intermesh with both the sun gear member214A and the ring gear member214C.

The planetary gear set216includes a sun gear member216C, a ring gear member216B and a planet gear carrier member216A that rotatably supports a set of planet gears216D (only one of which is shown) and a set of planet gears216E (only one of which is shown). The sun gear member216C is connected for common rotation with a fourth shaft or interconnecting member248and a fifth shaft or interconnecting member250. The ring gear member216B is connected for common rotation with a sixth shaft or interconnecting member252. It should be appreciated that the sixth member252may be broken up into several separate connected members without departing from the scope of the present invention. The planet carrier member216A is connected for common rotation with a seventh shaft or interconnecting member254and the output member222. The planet gears216D are each configured to intermesh with both the planet gears216E and the ring gear member216B. The planet gears216E are configured each to intermesh with both the planet gears216D and the sun gear member216C.

The planetary gear set218includes a sun gear member218A, a ring gear member218C and a planet gear carrier member218B that rotatably supports a set of planet gears218D (only one of which is shown). The sun gear member218A is connected for common rotation with an eighth shaft or interconnecting member256. The ring gear member218C is connected for common rotation with the sixth shaft or interconnecting member252. The planet carrier member218B is connected for common rotation with the seventh shaft or interconnecting member254. The planet gears218D are each configured to intermesh with both the sun gear member218A and the ring gear member218C.

The input shaft or member212is continuously connected to an engine (not shown) or to a turbine of a torque converter (not shown). The output shaft or member222is continuously connected with the final drive unit or transfer case (not shown).

The torque-transmitting mechanisms or clutches226,228and230and brakes232and234allow for selective interconnection of the shafts or interconnecting members, members of the planetary gear sets and the housing. For example, the first clutch226is selectively engageable to connect the third shaft or interconnecting member246with the fifth shaft or interconnecting member250. The second clutch228is selectively engageable to connect the sixth shaft or interconnecting member252with the second shaft or interconnecting member244and the input member212. The third clutch230is selectively engageable to connect the third shaft or interconnecting member246with the eighth shaft or interconnecting member256. The first brake232is selectively engageable to connect the fourth shaft or interconnecting member248with the stationary element or the transmission housing236in order to restrict the member248from rotating relative to the transmission housing236. The second brake234is selectively engageable to connect the sixth shaft or interconnecting member252with the stationary element or the transmission housing236in order to restrict the member252from rotating relative to the transmission housing236.

Referring now toFIG. 8andFIG. 9, the operation of the embodiment of the six speed transmission200will be described. It will be appreciated that transmission200is capable of transmitting torque from the input shaft or member212to the output shaft or member222in at least six 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 clutch226, second clutch228, third clutch230, first brake232and second brake234), as will be explained below.FIG. 9is a truth table presenting the various combinations of torque-transmitting mechanisms that are activated or engaged to achieve the various gear states. An “X” in the box means that the particular clutch or brake 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 not carrying torque. 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 transmission200. An example of the gear ratios that may be obtained using the embodiments of the present invention are also shown inFIG. 9. Of course, other gear ratios are achievable depending on the gear diameter, gear teeth count and gear configuration selected.

To establish a reverse gear, the first clutch226and the second brake234are engaged or activated. The first clutch226connects the third shaft or interconnecting member246with the fifth shaft or interconnecting member250. The second brake234connects the sixth shaft or interconnecting member252with the stationary element or the transmission housing236in order to restrict the member252from rotating relative to the transmission housing236. Likewise, the six forward ratios are achieved through different combinations of clutch and brake engagement, as shown inFIG. 9.

It will be appreciated that the foregoing explanation of operation and gear states of the six speed transmission200assumes, first of all, that all the clutches not specifically referenced in a given gear state are inactive or disengaged and, second of all, that during gear shifts, i.e., changes of gear state, between at least adjacent gear states, a clutch engaged or activated in both gear states will remain engaged or activated.

Referring now toFIG. 10, another embodiment of a six speed transmission300is illustrated in a lever diagram format. The transmission300includes an input shaft or member312, a first planetary gear set314, a second planetary gear set316, a third planetary gear set318and an output shaft or member322. The first planetary gear set314has three nodes: a first node314A, a second node314B and a third node314C. The second planetary gear set316has three nodes: a first node316A, a second node316B and a third node316C. The third planetary gear set318has three nodes: a first node318A, a second node318B and a third node318C.

The input member312is continuously coupled to the second node314B of the first planetary gear set314. The output member322is coupled to the first node318A of the third planetary gear set318. The third node316C of the second planetary gear set316is coupled to the third node318C of the third planetary gear set318. The second node316B of the second planetary gear set316is coupled to the second node318B of the third planetary gear set318. The third node314C of the first planetary gear set314is coupled to a stationary member or a transmission housing336.

A first clutch326selectively connects the input member312and the second node314B of the first planetary gear set314with the third node316C of the second planetary gear set316and the third node318C of the third planetary gear set318. A second clutch328selectively connects the input member314and the second node314B of the first planetary gear set314with the first node316A of the second planetary gear set316. A third clutch330selectively connects the first node314A of the first planetary gear set314with the first node316A of the second planetary gear set316. A first brake332selectively connects the third node316C of the second planetary gear set316and the third node318C of the third planetary gear set318with a stationary member or transmission housing336. A second brake334selectively connects the second node316B of the second planetary gear set316and the second node318B of the third planetary gear set318with a stationary member or transmission housing336.

Referring now toFIG. 11, a stick diagram presents a schematic layout of the embodiment of the six speed transmission300according to the present invention. InFIG. 11, the numbering from the lever diagram ofFIG. 10is carried over. The clutches 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 planetary gear set314includes a sun gear member314C, a ring gear member314A and a planet gear carrier member314B that rotatably supports a set of planet gears314D (only one of which is shown). The sun gear member314C is connected for common rotation with a first shaft or interconnecting member342. The ring gear member314A is connected for common rotation with a second shaft or interconnecting member344. The planet carrier member314B is connected for common rotation with the input member312. The planet gears314D are each configured to intermesh with both the sun gear member314C and the ring gear member314A.

The planetary gear set316includes a sun gear member316A, a ring gear member316C and a planet gear carrier member316B that rotatably supports a set of planet gears316D (only one of which is shown). The sun gear member316A is connected for common rotation with a third shaft or interconnecting member346. The ring gear member316C is connected for common rotation with a fourth shaft or interconnecting member348. The planet carrier member316B is connected for common rotation with a fifth shaft or interconnecting member350. The planet gears316D are each configured to intermesh with both the sun gear member316A and the ring gear member316C.

The planetary gear set318includes a sun gear member318C, a ring gear member318A and a planet gear carrier member318B that rotatably supports a set of planet gears318D (only one of which is shown). The sun gear member318C is connected for common rotation with a sixth shaft or interconnecting member352and the fourth shaft or interconnecting member348. The ring gear member318A is connected for common rotation with the output member322. The planet carrier member318B is connected for common rotation with a seventh shaft or interconnecting member354and with the fifth shaft or interconnecting member350. The planet gears318D are each configured to intermesh with both the sun gear member318C and the ring gear member318A.

The input shaft or member312is continuously connected to an engine (not shown) or to a turbine of a torque converter (not shown). The output shaft or member322is continuously connected with the final drive unit or transfer case (not shown).

The torque-transmitting mechanisms or clutches326,328,330and brakes332and334allow for selective interconnection of the shafts or interconnecting members, members of the planetary gear sets and the housing. For example, the first clutch326is selectively engageable to connect the input member312with the fourth shaft or interconnecting member348. The second clutch328is selectively engageable to connect the third shaft or interconnecting member346with the input member312. The third clutch330is selectively engageable to connect the third shaft or interconnecting member346with the second shaft or interconnecting member344. The first brake332is selectively engageable to connect the sixth shaft or interconnecting member352with the stationary element or the transmission housing336in order to restrict the member352from rotating relative to the transmission housing336. The second brake334is selectively engageable to connect the seventh shaft or interconnecting member354and the fifth shaft or interconnecting member350with the stationary element or the transmission housing336in order to restrict the members354,350from rotating relative to the transmission housing336.

Referring now toFIGS. 11 and 12, the operation of the embodiment of the six speed transmission300will be described. It will be appreciated that transmission300is capable of transmitting torque from the input shaft or member312to the output shaft or member322in at least six 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 clutch326, second clutch328, third clutch330, first brake332and second brake334), as will be explained below.FIG. 12is a truth table presenting the various combinations of torque-transmitting mechanisms that are activated or engaged to achieve the various gear states. An “X” in the box means that the particular clutch or brake is engaged to achieve the desired gear state. 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 transmission300. An example of the gear ratios that may be obtained using the embodiments of the present invention are also shown inFIG. 12. Of course, other gear ratios are achievable depending on the gear diameter, gear teeth count and gear configuration selected.

To establish a reverse gear, the first clutch326and the second brake334are engaged or activated. The first clutch326connects the input member312with the fourth shaft or interconnecting member348. The second brake334connects the seventh shaft or interconnecting member354and the fifth shaft or interconnecting member350with the stationary element or the transmission housing336in order to restrict the members354,350from rotating relative to the transmission housing336. Likewise, the six forward ratios are achieved through different combinations of clutch and brake engagement, as shown inFIG. 12.

It will be appreciated that the foregoing explanation of operation and gear states of the six speed transmission300assumes, first of all, that all the clutches not specifically referenced in a given gear state are inactive or disengaged and, second of all, that during gear shifts, i.e., changes of gear state, between at least adjacent gear states, a clutch engaged or activated in both gear states will remain engaged or activated.

Referring now toFIG. 14, another embodiment of a six speed transmission400is illustrated in a lever diagram format. The transmission400includes an input shaft or member412, a first planetary gear set414, a second planetary gear set416, a third planetary gear set418and an output shaft or member422. The first and second planetary gear sets414,416are represented by a single lever sharing common node points. The first planetary gear set414has three nodes: a first node414A, a second node414B and a third node414C. The second planetary gear set416has three nodes: a first node416A, a second node416B and a third node416C. The third planetary gear set418has three nodes: a first node418A, a second node418B and a third node418C.

The input member412is continuously coupled to the first node418A of the third planetary gear set418. The output member422is coupled to the second node414B of the first planetary gear set414and to the second node416B of the second planetary gear set416. The third node418C of the third planetary gear set418is coupled to a stationary member or a transmission housing436. The second node416B of the second planetary gear set416is coupled to the second node414B of the first planetary gear set414. The third node414C of the first planetary gear set414is coupled to the third node416C of the second planetary gear set416.

A first clutch426selectively connects the input member412and the first node418A of the third planetary gear set418with the third node416C of the second planetary gear set416and the third node414C of the first planetary gear set414. A second clutch428selectively connects the second node418B of the third planetary gear set418with the first node416A of the second planetary gear set416. A third clutch430selectively connects the second node418B of the third planetary gear set418with the first node414A of the first planetary gear set414. A first brake432selectively connects the first node416A of the second planetary gear set416with a stationary member or transmission housing436. A second brake434selectively connects the third node416C of the second planetary gear set416and the third node414C of the first planetary gear set414with a stationary member or transmission housing436.

Referring now toFIG. 14, a stick diagram presents a schematic layout of the embodiment of the six speed transmission400according to the present invention. InFIG. 14, the numbering from the lever diagram ofFIG. 13is carried over. The clutches 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.

The planetary gear sets414and416are a combined, or Ravigneaux, gear set. The planetary gear set414includes a sun gear member414A and the planetary gear set416includes a sun gear member416A and a ring gear member416B. The planetary gear sets414and416share a common planet gear carrier member460. The planetary carrier460is formed by combining the planet carrier member414C of the first planetary gear set414and the planet carrier member416C of the second planetary gear set416into a single planetary carrier460. The planetary carrier member460rotatably supports a first set of planet gears414D (only one of which is shown) and a second set of planet gears416D (only one of which is shown). In addition, the first planetary gear set414does not include a separate ring gear. Instead, the planetary gear set414“uses”, effectively, the ring gear416B of the second planetary gear set416through the meshing relationship of a first and a second set of planet gears414D and416D, the sun gear414A and ring gear416B.

The sun gear member414A is connected for common rotation with a first shaft or interconnecting member442. The planetary carrier member460is connected for common rotation with a second shaft or interconnecting member444and a third shaft or interconnecting member446. The sun gear member416A is connected for common rotation with a fourth shaft or interconnecting member448. The ring gear member416B is connected for common rotation with the output member422. The first set of planet gears414D each are configured to intermesh the sun gear member414A at a first end462of the planet gears414D and each are configured to intermesh with the planet gears416D at a second end464of the planet gears414D. The second set of planet gears416D are each configured to also intermesh with the sun gear416A and the ring gear member416B.

The planetary gear set418includes a sun gear member418C, a ring gear member418A and a planet gear carrier member418B that rotatably supports a set of planet gears418D (only one of which is shown). The sun gear member418C is connected for common rotation with a stationary member or the transmission housing436to prevent the sun gear member418C from rotating relative to the transmission housing436. The ring gear member418A is connected for common rotation with the input member412. The planet carrier member418B is connected for common rotation with a fifth shaft or interconnecting member450. The planet gears418D are each configured to intermesh with both the sun gear member418C and the ring gear member418A.

The input shaft or member412is continuously connected to an engine (not shown) or to a turbine of a torque converter (not shown). The output shaft or member422is continuously connected with the final drive unit or transfer case (not shown).

The torque-transmitting mechanisms or clutches426,428,430and brakes432and434allow for selective interconnection of the shafts or interconnecting members, members of the planetary gear sets and the housing. For example, the first clutch426is selectively engageable to connect the input member412with the third shaft or interconnecting member446. The second clutch428is selectively engageable to connect the fourth shaft or interconnecting member448with the fifth shaft or interconnecting member450. The third clutch430is selectively engageable to connect the first shaft or interconnecting member442with the fifth shaft or interconnecting member450. The first brake432is selectively engageable to connect the fourth shaft or interconnecting member448with the stationary element or the transmission housing436in order to restrict the member448from rotating relative to the transmission housing436. The second brake434is selectively engageable to connect the second shaft or interconnecting member444with the stationary element or the transmission housing436in order to restrict the member444from rotating relative to the transmission housing436.

Referring now toFIGS. 14 and 15, the operation of the embodiment of the six speed transmission400will be described. It will be appreciated that transmission400is capable of transmitting torque from the input shaft or member412to the output shaft or member422in at least six 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 clutch426, second clutch428, third clutch430, first brake432and second brake434), as will be explained below.FIG. 15is a truth table presenting the various combinations of torque-transmitting mechanisms that are activated or engaged to achieve the various gear states. An “X” in the box means that the particular clutch or brake is engaged to achieve the desired gear state. 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 transmission400. An example of the gear ratios that may be obtained using the embodiments of the present invention are also shown inFIG. 15. Of course, other gear ratios are achievable depending on the gear diameter, gear teeth count and gear configuration selected.

To establish a reverse gear, the second clutch428and the second brake434are engaged or activated. The second clutch428connects the fourth shaft or interconnecting member448with the fifth shaft or interconnecting member450. The second brake434connects the second shaft or interconnecting member444with the stationary element or the transmission housing436in order to restrict the member444from rotating relative to the transmission housing436. Likewise, the six forward ratios are achieved through different combinations of clutch and brake engagement, as shown inFIG. 15.

It will be appreciated that the foregoing explanation of operation and gear states of the six speed transmission400assumes, first of all, that all the clutches not specifically referenced in a given gear state are inactive or disengaged and, second of all, that during gear shifts, i.e., changes of gear state, between at least adjacent gear states, a clutch engaged or activated in both gear states will remain engaged or activated.