Endless belt power transmission systems or components – Plural belts or plural output loads – Plural output loads
Patent
1997-12-09
2000-02-01
Hannon, Thomas R.
Endless belt power transmission systems or components
Plural belts or plural output loads
Plural output loads
474 94, 474150, 464 52, F16H 700, F16H 5514, F16H 724, F16C 100
Patent
active
060196920
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a belt drive device mounted on an engine main unit and capable of transmitting the turning force of a crankshaft on the driving side to a camshaft and other engine accessories on the driven side via an endless toothed belt. More particularly, the invention concerns a belt drive device having a dynamic damper disposed in a revolution transmission system of a timing belt.
BACKGROUND ART
An internal combustion engine, for example, a diesel engine, drives a camshaft and other engine accessories by the turning force of a crankshaft. Usually, the turning force of the crankshaft is transmitted to a fuel injection pump, a balance shaft, and a camshaft via an endless toothed belt.
A timing belt used in this belt drive device undergoes fluctuations in revolution from the camshaft or engine accessories during engine driving. Thus, a load on the timing belt increases or decreases.
For instance, a belt drive device of a diesel engine 100 is shown in FIG. 9. This belt drive device has a revolution transmission system for transmitting a turning force from a crank sprocket 101 to a cam sprocket 103 and a fuel injection pump sprocket 104 via a timing belt 102. The numeral 105 denotes an idler. If the diesel engine 100 is 4-cylindered, torque fluctuations of the crankshaft repeat a fluctuation pattern comprising two explosion torque fluctuations and two inertia torque fluctuations per revolution of the crankshaft as shown in FIG. 10. Torque fluctuations of the camshaft, on the other hand, repeat a specific fluctuation pattern for each cylinder as shown in FIG. 11. Furthermore, torque fluctuations of the fuel injection pump repeat a specific fluctuation pattern per injection as shown in FIG. 12.
Thus, as shown in FIG. 13, revolution fluctuations of the crankshaft follow a line a, revolution fluctuations of the camshaft follow a line b, and revolution fluctuations of the fuel injection pump follow a line c, in the entire revolution speed range of the diesel engine 100. In this case, the load on the timing belt 102 changes as shown in a solid line A on the tension side of the fuel injection pump sprocket 104. Particularly at a predetermined engine speed Ne.sub.1, resonance occurs, maximizing the load on the timing belt.
That is, a string such as the timing belt (the tension side of the fuel injection pump sprocket) is known to resonate. At the time of resonance, the load is known to peak. It is also known that its basic resonance frequency is inversely proportional to the length of the string, and is proportional to the square root of the ratio of the tension of the string to the linear density of the string.
With the belt drive device, the timing belt load is thus maximal at resonance. In setting the strength of the timing belt, and for ensuring its durability, therefore, the sectional shape, tension, material, and string vibration interval of the timing belt are suitably set so that the timing belt will have a sufficiently larger allowable limit of load P.sub.max than the timing belt load Ph. Besides, the length, tension, and linear density of the string are selected so that the engine speed Ne.sub.1 at resonance is excluded from the normal engine speed range. Actually, however, the belt drive device is required to have full durability, and yet is subject to restrictions on layout. The present situation is that sufficiently effective measures cannot be taken.
In reducing the timing belt load of such a belt drive device, it is known to use a dynamic damper. FIG. 14 shows that an inertial body B with the moment of inertia I.sub.B is supported on the substrate side via an elastic body with a spring constant K.sub.B, and an inertial body D with the moment of inertia I.sub.D is connected to the inertial body B via an elastic body with a spring constant K.sub.D. In this case, the inertial body D vibrating at a torsion angle .theta..sub.D acts as a dynamic damper d on a vibration system b in which the inertial body B vibrates at a torsion angle .theta..sub.B.
Basically, if the na
REFERENCES:
patent: 5405296 (1995-04-01), Cerny et al.
Hatano Kiyoshi
Imai Satoshi
Kojima Ichiyo
Nishihara Setsuo
Hannon Thomas R.
Kaness Matthew A.
Mitsubishi Jidosha Kogyo Kabushiki Kaisha
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