# US 2016/0258476 A1 · Crankshaft for reciprocating engine

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- Number: US 2016/0258476 A1
- Document ID: US20160258476A1
- Status: Published application
- Kind: A1
- Application number: 15/028,445
- Filed: 2014-10-14
- Published: 2016-09-08
- Earliest claimed: 2013-10-16
- Assignees: Nippon Steel & Sumitomo Metal Corporation
- Applicants: Nippon Steel & Sumitomo Metal Corporation
- Inventors: Koichiro ISHIHARA; Kenji IMANISHI; Ken YOSHINO; Kunihiro YABUNO
- Web page: https://patentgrep.com/patent/US20160258476A1

## CPC

- F16C 3/20: Shape of crankshafts or eccentric-shafts having regard to balancing
- F16C 3/06: Crankshafts
- F16C 3/08: made in one piece (features relating to lubrication F16C3/14, to cooling F16C3/16)
- F16C: SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS

## Abstract

A crankshaft includes: journals that define a central axis of rotation; crank pins that are eccentric with respect to the journals; and crank arms for connecting the journals and the crank pins, wherein each of the crank arms or at least one of the crank arms integrally includes a counterweight. The crank arms have a recess in a surface adjacent to a corresponding one of the journals, the recess disposed inward of a peripheral region along a periphery of the surface, the recess disposed along the peripheral region. With this configuration, it is possible to provide a crankshaft which has reduced weight and increased torsional rigidity in combination with increased flexural rigidity.

## Claims

### Claim 1

A crankshaft for a reciprocating engine, the crankshaft configured to be mounted in a reciprocating engine, the crankshaft comprising:
journals that define a central axis of rotation;
crank pins that are eccentric with respect to the journals; and
crank arms, each of the crank arms connecting a corresponding one of the journals to a corresponding one of the crank pins,
wherein each of the crank arms or at least one of the crank arms integrally includes a counterweight, and
wherein the crank arms have a recess in a surface adjacent to the corresponding one of the journals, the recess disposed inward of a peripheral region along a periphery of the surface, the recess disposed along the peripheral region, so that, in the crank arm, a central region inward of the recess is thick.

### Claim 2 (depends on 1)

The crankshaft for a reciprocating engine according to claim 1,
wherein the recess extends to a portion of the peripheral region, the portion corresponding to an area in the corresponding one of the crank pins, the area extending from an axis of the crank pin to an eccentrically top portion of the crank pin.

### Claim 3 (depends on 2)

The crankshaft for a reciprocating engine according to claim 2,
wherein the recess extends to an area of the peripheral region, the area corresponding to the top portion.

### Claim 4 (depends on 2)

The crankshaft for a reciprocating engine according to claim 2,
wherein the recess extends to a side area of the peripheral region.

### Claim 5 (depends on 2)

The crankshaft for a reciprocating engine according to claim 2,
wherein the recess extends to two side areas of the peripheral region, the recess being symmetrical with respect to a line connecting an axis of the corresponding one of the journals to the axis of the corresponding one of the crank pins.

### Claim 6 (depends on 1)

The crankshaft for a reciprocating engine according to claim 1,
wherein, of all the crank arms, a crank arm not having the counterweight has a recess in a surface adjacent to the corresponding one of the crank pins, the recess disposed inward of a peripheral region along a periphery of the surface, the recess disposed along the peripheral region.

### Claim 7 (depends on 2)

The crankshaft for a reciprocating engine according to claim 2,
wherein, of all the crank arms, a crank arm not having the counterweight has a recess in a surface adjacent to the corresponding one of the crank pins, the recess disposed inward of a peripheral region along a periphery of the surface, the recess disposed along the peripheral region.

### Claim 8 (depends on 3)

The crankshaft for a reciprocating engine according to claim 3,
wherein, of all the crank arms, a crank arm not having the counterweight has a recess in a surface adjacent to the corresponding one of the crank pins, the recess disposed inward of a peripheral region along a periphery of the surface, the recess disposed along the peripheral region.

### Claim 9 (depends on 4)

The crankshaft for a reciprocating engine according to claim 4,
wherein, of all the crank arms, a crank arm not having the counterweight has a recess in a surface adjacent to the corresponding one of the crank pins, the recess disposed inward of a peripheral region along a periphery of the surface, the recess disposed along the peripheral region.

### Claim 10 (depends on 5)

The crankshaft for a reciprocating engine according to claim 5,
wherein, of all the crank arms, a crank arm not having the counterweight has a recess in a surface adjacent to the corresponding one of the crank pins, the recess disposed inward of a peripheral region along a periphery of the surface, the recess disposed along the peripheral region.