Planetary gear transmission systems or components – With means to vary drive ratio or disconnect drive – Plural elements selectively braked
Reexamination Certificate
2002-07-08
2004-10-26
Marmor, Charles A (Department: 3681)
Planetary gear transmission systems or components
With means to vary drive ratio or disconnect drive
Plural elements selectively braked
C475S277000, C475S279000, C475S280000, C475S281000
Reexamination Certificate
active
06808469
ABSTRACT:
This application is based on Japanese Patent Application Nos. 2001-308925, 2001-206471 and 2002-145513 filed Oct. 4, 2001, Jul. 6, 2001 and May 20, 2002, respectively, the contents of which are incorporated hereinto by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a planetary gear type multiple-step transmission interposed between a drive power source and drive wheels of a vehicle such as an automobile and a railcar.
2. Discussion of Related Art
For vehicles, there are widely used planetary gear type multiple-step transmissions which have a plurality of predetermined speed ratios or operating positions (gear positions) that are selectively established. Such planetary gear type multiple-step transmissions are desired to be not only simple in construction and small in size and to provide a large number of operating positions and a wide range of speed ratio, but also to provide speed ratios that change as geometric series or nearly geometric series.
There has been proposed a planetary gear type multiple-step transmission which has seven operating positions. Representative examples of this kind of planetary gear type multiple-step transmission include a transmission of a third embodiment of
FIGS. 5 and 6
and a transmission of a fourth embodiment of
FIGS. 7 and 8
of JP-A-2000-266138. Although these transmissions provide a relatively large number of operating positions and a relatively wide range of speed ratio, the transmissions have a large overall length due to the use of four planetary gear sets, and undesirably suffer from a relatively low degree of freedom in its installation on a vehicle.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a small-sized planetary gear type multiple-step transmission which has a relatively large number of operating positions and a relatively wide range of speed ratio.
The above object may be achieved according to a first aspect of this invention, which provides a planetary gear type multiple-step transmission for a vehicle, having seven forward drive positions for driving the vehicle in a forward direction, the seven forward drive positions including a first-speed, a second-speed, a third-speed, a fourth-speed, a fifth-speed, a sixth-speed and a seventh-speed position, the transmission comprising an input rotary member, an output rotary member, a first, a second and a third planetary gear set each including a sun gear, a carrier and a ring gear, and further comprising a first, a second and a third brake, and a first, a second, a third and a fourth clutch, wherein an improvement comprises:
(a) a first, a second, a third, a fourth and a fifth rotary element each of which is constituted by at least one of the sun gears, carriers and ring gears of the first, second and third planetary gear sets, and rotating speeds of the first, second, third, fourth and fifth rotary elements being represented by respective parallel straight lines of a collinear chart, which lines are arranged in a direction from one of opposite ends of the collinear chart toward the other end, the first rotary element being selectively brought to a stationary state by the first brake, and the second rotary element being selectively brought to a stationary state by the second brake, while the third rotary element being selectively brought to a stationary state by the third brake, the fifth, third and first rotary elements being selectively connected to the input rotary member by the first, second and third clutches, respectively, and the third rotary element being selectively connected to the input rotary member through the second clutch, and the third rotary element rotary element being selectively brought to a disconnected state by the fourth clutch, while the fourth rotary element being connected to the output rotary member; and
(b) the first-speed position being established by engaging the first clutch and the third brake, or the first and fourth clutches and the third brake, and the second-speed position being established by first clutch and the second brake, while the third-speed position being established by engaging the first and fourth clutches and the first brake, the fourth-speed position being established by engaging the first and second clutches and the first brake, the fifth-speed positioning being established by engaging the first, second and fourth clutches, the sixth-speed position being established by engaging the second and fourth clutches and the first brake, the seventh-speed position being established by engaging the second and fourth clutches and the second brake.
In a first preferred form of the transmission according to the first aspect of this invention, each of the first, second and third planetary gear sets is a single-pinion type planetary gear set, and the first rotary element consists of the sun gear of the first planetary gear set, and the second rotary element consists of the carrier of the first planetary gear set and the ring gear of the second planetary gear set, while the third rotary element consists of the ring gear of the first planetary set, the carrier of the second planetary gear set and the ring gear of the third planetary gear set, the fourth rotary element consisting of the carrier of the third planetary gear set, and the fifth rotary element consisting of the sun gear and the of the second planetary gear set and the sun gear of the third planetary gear set.
In a second preferred form of the transmission according to the first aspect of the invention, the first planetary gear set is a double-pinion type planetary gear set, while each of the second and third planetary gear sets is a single-pinion type planetary gear set, and the first rotary element consists of the sun gear of the first planetary gear set, and the second rotary element consists of the ring gear of the first planetary gear set and the ring gear of the second planetary gear set, while the third rotary element consists of the carrier of the first planetary set, the carrier of the second planetary gear set and the ring gear of the third planetary gear set, the fourth rotary element consisting of the carrier of the third planetary gear set, and the fifth rotary element consisting of the sun gear and the of the second planetary gear set and the sun gear of the third planetary gear set.
In a third preferred form of the transmission according to the first aspect of this invention, the first planetary gear set is a double-pinion type planetary gear set, while each of the second and third planetary gear sets is a single-pinion type planetary gear set, and the first rotary element consists of the carrier of the first planetary gear set, and the second rotary element consists of the ring gear of the first planetary gear set and the ring gear of the second planetary gear set, while the third rotary element consists of the sun gear of the first planetary set, the carrier of the second planetary gear set and the ring gear of the third planetary gear set, the fourth rotary element consisting of the carrier of the third planetary gear set, and the fifth rotary element consisting of the sun gear and the of the second planetary gear set and the sun gear of the third planetary gear set.
In the planetary gear type multiple-step transmission according to the first aspect of the present invention described above, the first, second and third planetary gear sets are arranged to provide providing a sufficiently wide range of speed ratio, thereby permitting not only high-speed running of the vehicle, but also stable starting of the vehicle on an uphill road, without an increase of the required size of the transmission.
In one advantageous arrangement of the first, second and third preferred forms of the first aspect of the invention described above, the transmission further has a rear drive position for driving the vehicle in a reverse direction, the rear drive position being established by engaging the third and fourth clutches and the third brake, the first, second and third planetary gear sets having re
Hojo Yasuo
Hoshino Akira
Miyazaki Terufumi
Tabata Atsushi
Le David D.
Marmor Charles A
Oblon, Spivak, McClelland, Maier & Neustadt PC
Toyota Jidosha & Kabushiki Kaisha
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