# US 10,865,837 B2 · Automatic transmission

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- Number: US 10,865,837 B2
- Document ID: US10865837B2
- Status: Granted
- Kind: B2
- Application number: 16/254,816
- Filed: 2019-01-23
- Published: 2019-08-22
- Granted: 2020-12-15
- Earliest claimed: 2018-02-20
- Assignees: Mazda Motor Corporation
- Applicants: Mazda Motor Corporation
- Inventors: Shota Yamakawa; Tatsuhiko Iwasaki; Tomotaka Ishizaka
- Web page: https://patentgrep.com/patent/US10865837B2

## CPC

- F16D 25/0638: with more than two discs, e.g. multiple lamellae
- F16H 57/10: Braking arrangements
- F16D 65/186: {with full-face force-applying member, e.g. annular}
- F16H 63/3026: {comprising friction clutches or brakes (band brake actuating mechanisms F16H63/3003)}
- F16D 55/40: actuated by a fluid-pressure device arranged in or one the brake
- F16D 65/853: with closed cooling system
- F16D 2048/0212: {Details of pistons for primary or secondary cylinders especially adapted for fluid control}
- F16H 3/663: {with conveying rotary motion between axially spaced orbital gears, e.g. a stepped orbital gear or Ravigneaux}
- F16H 57/0473: {Friction devices, e.g. clutches or brakes}
- F16H 57/0484: {with variable gear ratio or for reversing rotary motion}
- F16H 2063/303: {the friction member is actuated and released by applying pressure to different fluid chambers}
- F16H 2200/006: the gear ratios comprising eight forward speeds
- F16H 2200/2012: with four sets of orbital gears
- F16H 2200/2043: with five engaging means
- F16D: COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16H: GEARING

## Abstract

An automatic transmission is provided, which includes a friction engaging element. The friction engaging element includes a plurality of friction plates disposed inside a transmission case, a piston configured to cause the plurality of friction plates to be engaged with each other, and a spring configured to bias the piston. The spring includes a first spring and a second spring with a longer free length than the first spring, and the first spring and the second spring are aligned in circumferential directions of the transmission case.

## Claims

### Claim 1

An automatic transmission comprising a friction engaging element, the friction engaging element including:
a plurality of friction plates disposed inside a transmission case;
a piston configured to cause the plurality of friction plates to be engaged with each other;
a spring configured to bias the piston, the spring including a first spring and a second spring with a longer free length than the first spring, and the first spring and the second spring being aligned in circumferential directions of the transmission case; and
a hydraulic chamber to which hydraulic fluid is supplied, the hydraulic fluid biasing the piston,
wherein the hydraulic chamber includes a first hydraulic chamber for engagement to which hydraulic fluid to bias the piston in an engaging direction is supplied to cause the plurality of friction plates to be engaged with each other, and a second hydraulic chamber for release disposed at an opposite side of the piston from the first hydraulic chamber for engagement, the second hydraulic chamber for release being supplied with hydraulic fluid to bias the piston in a releasing direction opposite from the engaging direction,
wherein the second hydraulic chamber for release is formed to have a smaller outer diameter than the first hydraulic chamber for engagement, and
wherein a biasing force receiving member configured to receive the biasing force of the first spring and the second spring is coupled to the piston and is disposed at an outer circumferential side of the second hydraulic chamber for release.

### Claim 2 (depends on 1)

The automatic transmission of claim 1,
wherein the second hydraulic chamber for release and the first hydraulic chamber for engagement are disposed so as to overlap with each of the first spring and the second spring in a radially internal and external relationship.

### Claim 3 (depends on 2)

The automatic transmission of claim 2, further comprising:
a first retainer plate holding a first end part of the first spring and a first end part of the second spring; and
a second retainer plate, disposed so as to be axially separated from the first retainer plate, holding a second end part of the first spring, and having an insertion hole into which the second spring is inserted so that a second end part of the second spring is projectable in a direction opposite from the first retainer plate.

### Claim 4 (depends on 1)

The automatic transmission of claim 1, further comprising:
a first retainer plate holding a first end part of the first spring and a first end part of the second spring; and
a second retainer plate, disposed so as to be axially separated from the first retainer plate, holding a second end part of the first spring, and having an insertion hole into which the second spring is inserted so that a second end part of the second spring is projectable in a direction opposite from the first retainer plate.