US 5,853,344 AGranted

Automatic transmission

AssigneeAisin Aw Co., Ltd.

InventorsKazumasa Tsukamoto, Masahiro Hayabuchi, Masaaki Nishida, Kengo Nomura, Takashi Morimoto

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Abstract

Smooth driving of a vehicle is achieved by eliminating busy shift by providing a small gear ratio step between the two highest gear ranges while maintaining structural compactness of the transmission. In the second highest gear range or state, a first pinion P1 has a diameter smaller than that of a second pinion P2, both pinions P1 and P2 being coupled integrally and at least partially determining the second highest gear ratio. The gear ratio .lambda..sub.2 in the second highest gear range is described as 1+(Z.sub.S2 /Z.sub.R1).times.(Z.sub.P1 /Z.sub.P2). Since (Z.sub.P1 /Z.sub.P2) is always equal to 1.0 or less, the gear ratio can be made smaller without enlarging the diameter of the ring gear R1 significantly to decrease the gear ratio step to the highest gear range.

Claims5

Dependent claims

An automatic transmission comprising an input member to which motive power is applied, an output member from which the motive power is transmitted, and a planetary gear unit connecting the input member to the output member, wherein rotation from the input member is output to the output member via one of a plurality of transmission gear states of the planetary gear unit, said planetary gear unit comprising

a first ring gear,
a first pinion engaging the first ring gear,
a second pinion coupled to the first pinion so as to rotate integrally therewith,
a third pinion engaging the second pinion,
a second ring gear engaging the third pinion,
a first sun gear engaging the second pinion,
a carrier coupled to the output member and supporting the first, second and third pinions,
said first pinion having a diameter smaller than that of said second pinion, and
gear state setting means for achieving a first gear state range by transmitting rotation of the input member to the first ring gear and by stopping the second ring gear, for achieving a second range by transmitting rotation of the input member to the first ring gear and by stopping the first sun gear, and for achieving a third range by rotating the planetary gear unit integrally with the input member,
said smaller diameter of the first pinion relative to the diameter of the second pinion producing reduced output gear ratio in said first and second gear states.

7 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/675,904Filed 5 Jul 1996
Priority: JP 7-1711786 Jul 1995
Granted: 29 Dec 1998
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

F16H 3/663
Composed of a number of gear trains without drive passing from one train to another: with conveying rotary motion between axially spaced orbital…
F16H 2200/0039
Characterised by the number of forward speeds: the gear ratios comprising three forward speeds
F16H 2200/0047
Characterised by the number of forward speeds: the gear ratios comprising five forward speeds
F16H 2200/2005
Characterised by the number of sets of orbital gears: with one sets of orbital gears