Automatic transmission for an automotive vehicle

Claim 2

A transmission for an automotive vehicle, comprising: an input shaft; an output shaft; a coupling device having an input portion thereof connected to said input shaft; gear means for transmitting power from said coupling device to said output shaft in such a way that three forward and one reverse drives can be obtained, said gear means including first, second, third and fourth rotatable members, said fourth rotatable member being connected to said output shaft; first and second clutches provided between said gear means and said coupling device, said first clutch being connected to said first rotatable member of said gear means, said second clutch being connected to said second rotatable member of said gear means; a first brake for selectively braking said third rotatable member of said gear means; a second brake for selectively braking said second rotatable member of said gear means; a third clutch connected to said input shaft; and a planetary gear set for providing an overdrive having a predetermined gear ratio as a fourth forward drive, said predetermined gear ratio being established without affecting the gear ratios of said gear means whereby said gear ratios of said gear means are established by said rotatable members of said gear means independently of said planetary gear set, said planetary gear set having fifth, sixth and seventh rotatable members, said sixth and seventh rotatable members being connected to said gear means, said fifth rotatable member being connected to said third clutch, said over-drive being obtained when said third clutch and said second brake are engaged.

Claim 3

A transmission of claim 1, wherein said gear means includes two planetary gear sets which are arranged in such a manner that, when said first clutch and said first brake are engaged a first forward drive is obtained, when said first clutch and said second brake are engaged a second forward drive is obtained, when said first and third clutches are engaged a third forward drive is obtained, when said third clutch and said second brake are engaged said forward over-drive is obtained, and when second clutch and said first brake are engaged a reverse drive is obtained.

Claim 4

A transmission of claim 1, wherein said coupling device is a fluid coupling or hydraulic torque converter wherein said first and third clutches can be engaged so as to provide a split drive during a direct forward drive by directly connecting said input shaft with said planetary gear set.

Claim 5

A transmission of claim 1, wherein said coupling device is a torque converter.

Claim 6

A transmission of claim 1, wherein said fifth member is a ring gear, said sixth member is a sun gear and said seventh member is a carrier supporting a planetary pinion.

Claim 7

An automatic transmission for an automotive vehicle, comprising: an input shaft; an output shaft; a coupling device having an input portion thereof connected to said input shaft; a gear train set for transmitting power from said coupling device to said output shaft in such a way that three forward and one reverse drives can be obtained, said gear train set including a first planetary gear set having first, second, third and fourth rotatable members said fourth rotatable member being connected to said output shaft; first and second clutches provided between said gear train set and said coupling device, said first clutch being connected to said first rotatable member of said gear train set, said second clutch being connected to said second rotatable member of said gear train set; a first brake for selectively braking said third rotatable member of said gear train set; a second brake for selectively braking said second rotatable member of said gear train set; a third clutch connected to said input shaft; and a second planetary gear set for providing an overdrive having a predetermined gear ratio as a fourth forward drive, said predetermined gear ratio being established without affecting the gear ratios of said gear train set, whereby said gear ratios at said gear train set are established by said rotatable members of said gear train set independently of said second planetary gear set, said second planetary gear set having fifth, sixth and seventh rotatable members, said sixth and seventh rotatable members being connected to said first planetary gear set, said fifth rotatable member being connected to said third clutch so that the power from the input shaft can be transmitted to the fifth rotatable member of said second planetary gear set bypassing said coupling device, in such a way that the over-drive can be obtained when said second brake and said third clutch are engaged while the other clutches and brake are disengaged.

Claim 8

An automatic transmission for an automotive vehicle, comprising: an input shaft; an output shaft; a coupling device having an input portion thereof connected to said input shaft; a gear train set for transmitting power from said coupling device to said output shaft in such a way that three forward and one reverse drives can be obtained, said gear train set including a first planetary gear set having first, second, third and fourth rotatable members said fourth rotatable member being connected to said output shaft; first and second clutches provided between said gear train set and said coupling device, said first clutch being connected to said first rotatable member of said gear train set, said second clutch being connected to said second rotatable member of said gear train set; a first brake for selectively braking said third rotatable member of said gear train set; a second brake for selectively braking said second rotatable member of said gear train set; a third clutch connected to said input shaft; and a second planetary gear set for providing an overdrive having a predetermined gear ratio as a fourth forward drive, said predetermined gear ratio being established without affecting the gear ratios of said gear train set, whereby said gear ratios at said gear train set are established by said rotatable members of said gear train set independently of said second planetary gear set, said second planetary gear set having fifth, sixth and seventh rotatable members, said sixth and seventh rotatable members being connected to said first planetary gear set, said fifth rotatable member being connected to said third clutch so that the power from the input shaft can be transmitted to the fifth rotatable member of said second planetary gear set bypassing said coupling device, in such a way that the over-drive can be obtained when said second brake and said third clutch are engaged while the other clutches and brake are disengaged.

Claim 9

An automatic transmission as claimed in claim 6, wherein said third clutch is designed to function as a locking-up clutch.

Claim 10

An automatic transmission as claimed in claim 6, wherein the fifth, sixth and seventh rotatable members of said second planetary gear set are a ring gear, a sun gear, and a carrier for a planetary pinion, respectively.

Claim 11

An automatic transmission as claimed in claim 6, wherein said coupling device is a fluid coupling or hydraulic torque converter wherein said first and third clutches can be engaged so as to provide a split drive by directly connecting said input shaft with the fifth rotatable member of said second planetary gear set.

Claim 12

An automatic transmission as claimed in claim 6, wherein said coupling device is a torque converter.

Claim 13

An automatic transmission for an automotive vehicle, comprising an input shaft, an output shaft, a coupling device connected to said input shaft, a conventional three-speed gear train set with three forward speeds and one reverse drive, said three speed gear train being connected to said coupling device and including a first clutch, a second clutch, a first planetary gear set, a first brake, and a second brake, said first planetary set having first, second, third and fourth rotatable members, said first rotatable member being connected by way of said first clutch to said coupling device, said second rotatable member being connected by way of said second clutch to said coupling device and selectively braked by said second brake, said third rotatable member being selectively braked by said first brake; said fourth rotatable member being directly connected to said output shaft; a second planetary gear set having fifth, sixth and seventh rotatable members for providing an overdrive having a predetermined gear ratio as a fourth forward drive said predetermined gear ratio being established without affecting the gear ratios of said conventional three speed gear train set, whereby said gear ratios of said gear train set are established by said rotatable members of said gear train set independently of said second planetary gear set; a third clutch placed between said second planetary gear set and said input shaft; said fifth rotatable member being connected by way of said third clutch to said input shaft; said sixth and seventh rotatable members being connected to two rotatable members among said first, second, third and fourth rotatable members; a first forward speed being obtained by engaging said first clutch and said first brake; a second forward speed being obtained by engaging said first clutch and said second brake; a third forward speed being obtained by engaging said first and third clutches;

Claim 14

An automatic transmission for an automotive vehicle, comprising an input shaft, an output shaft, a coupling device connected to said input shaft, a conventional three-speed gear train set with three forward speeds and one reverse drive, said three speed gear train being connected to said coupling device and including a first clutch, a second clutch, a first planetary gear set, a first brake, and a second brake, said first planetary set having first, second, third and fourth rotatable members, said first rotatable member being connected by way of said first clutch to said coupling device, said second rotatable member being connected by way of said second clutch to said coupling device and selectively braked by said second brake, said third rotatable member being selectively braked by said first brake; said fourth rotatable member being directly connected to said output shaft; a second planetary gear set having fifth, sixth and seventh rotatable members for providing an overdrive having a predetermined gear ratio as a fourth forward drive said predetermined gear ratio being established without affecting the gear ratios of said conventional three speed gear train set, whereby said gear ratios of said gear train set are established by said rotatable members of said gear train set independently of said second planetary gear set; a third clutch placed between said second planetary gear set and said input shaft; said fifth rotatable member being connected by way of said third clutch to said input shaft; said sixth and seventh rotatable members being connected to two rotatable members among said first, second, third and fourth rotatable members; a first forward speed being obtained by engaging said first clutch and said first brake; a second forward speed being obtained by engaging said first clutch and said second brake; a third forward speed being obtained by engaging said first and third clutches;

Claim 15

said overdrive being obtained by engaging said third clutch and said second brake; and a reverse drive being obtained by engaging said second clutch and said first brake.

Claim 16

said overdrive being obtained by engaging said third clutch and said second brake; and a reverse drive being obtained by engaging said second clutch and said first brake.

Claim 17

An automatic transmission as claimed in claim 11, wherein said coupling device is a fluid coupling or hydraulic torque converter wherein said first and third clutches can be engaged so as to provide a split drive by directly connecting said input shaft with the fifth rotatable member of said second planetary gear set.

Claim 18

An automatic transmission as claimed in claim 11, wherein said coupling device is a torque converter.