# US 2014/0155208 A1 · Chain transmission device for driving camshaft

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- Number: US 2014/0155208 A1
- Document ID: US20140155208A1
- Status: Published application
- Kind: A1
- Application number: 14/234,421
- Filed: 2012-07-18
- Published: 2014-06-05
- Earliest claimed: 2011-07-25
- Assignees: Ntn Corporation
- Inventors: Akio Kato; Shinji Oishi
- Web page: https://patentgrep.com/patent/US20140155208A1

## CPC

- F16H 7/08: Means for varying tension of belts, ropes or chains (pulleys of adjustable construction F16H55/52)
- F02B 67/06: driven by means of chains, belts, or like endless members
- F16H 7/06: with chains
- F16H 7/18: Means for guiding or supporting belts, ropes, or chains (construction of pulleys F16H55/36)
- F16H 7/1281: {where the axis of the pulley moves along a substantially circular path}
- F16H 7/20: Mountings for rollers or pulleys
- F16H 2007/0865: {Pulleys}
- F16H 2007/0893: {Circular path}
- F16H: GEARING
- F02B: INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL (gas-turbine plants F02C; hot-gas or combustion-product positive-displacement engine plants F02G)

## Abstract

A timing chain (5) is looped over a driving sprocket (2) attached to a crankshaft (1) and driven sprockets (4) attached to camshafts (3). A pivotable chain guide (A1) having a plurality of rotatable rollers (41) for guiding movements of the timing chain (5) is provided on one side of the slack side of the timing chain (5). Adjustment force of a chain tensioner is applied to a remote end of the chain guide remote from the center of pivoting movement of the chain guide, thereby pressing the rollers (41) against the timing chain (5). The ratio (D1/D2) between the pitch circle diameter D1 of the driving sprocket (2) and the outer diameter D2 of the rollers (41) is determined within the range of 5/3 to 5/1. This prevents insufficient lubrication of the chain guiding rollers (41), makes it easy to lay out the engine.

## Claims

### Claim 1

A chain transmission device for driving a camshaft, comprising:
a driving sprocket mounted to a crankshaft;
a driven sprocket mounted to a camshaft;
a timing chain looped over the driving sprocket and the driven sprocket;
a pivotable chain guide provided on one side of a slack side of the timing chain, and retaining a plurality of rotatable rollers for guiding movements of the timing chains so as to be spaced from each other in a direction in which the timing chain is moved; and
a chain tensioner for applying an adjustment force to a remote end of the chain guide remote from a center of pivoting movement of the chain guide, thereby pressing the rollers against the timing chain,
wherein the driving sprocket and the rollers are designed such that
a ratio (D1/D2) between a pitch circle diameter D1 of the driving sprocket and an outer diameter D2 of the rollers is within a range of 5/3 to 5/1.

### Claim 2 (depends on 1)

The chain transmission device according to claim 1, further comprising a fixed chain guide fixed in position on one side of a tight side of the timing chain, and having the same configuration as the pivotable chain guide.

### Claim 3 (depends on 1)

The chain transmission device according to claim 1, wherein the rollers comprise roller bearings each comprising an outer race and a plurality of roller elements mounted in the outer race.

### Claim 4 (depends on 2)

The chain transmission device according to claim 2, wherein the rollers comprise roller bearings each comprising an outer race and a plurality of roller elements mounted in the outer race.