Endless belt power transmission systems or components – Pulley with belt-receiving groove formed by drive faces on... – Including lubrication or particular guide or bearing for...
Patent
1996-11-01
1998-03-10
Schoeppel, Roger J.
Endless belt power transmission systems or components
Pulley with belt-receiving groove formed by drive faces on...
Including lubrication or particular guide or bearing for...
474199, 384510, F16H 5536
Patent
active
057254486
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to an idler pulley, particularly to an idler pulley engaged with a timing belt or auxiliary machine driving belt for automobiles. An idler pulley is used with a timing belt for automobile engines to increase the belt wrapping angle and to impart a suitable tension to the belt. Idler pulleys include one (hat type outer race) in the form in which the pulley peripheral surface to be contacted by the belt is provided directly on the outer diameter of the outer race of a ball bearing and another, which is in frequent use, in the form in which as shown in FIG. 23 a pulley body 11 having a pulley peripheral surface 11a1 and a ball bearing 12 are integrally fitted together.
The pulley body 11 is made by pressing a steel plate, having an outer diameter cylindrical portion 11a and an inner diameter cylindrical portion 11b for having the outer race 12b of the ball bearing 12 fitted therein. The pulley peripheral surface 11a1 is disposed on the outer diameter of the outer diameter cylindrical portion 11a. The ball bearing 12 is a deep groove ball bearing comprising an outer race 12b fitted in the inner diameter cylindrical portion 11b of the pulley body 11, an inner race 12a fitted on a fixed shaft (omitted from illustration), a plurality of balls 12c held between the raceway surface of the inner race 12a and the raceway surface of the outer race 12b, a retainer 12d for holding the balls 12c, and a seal 12e for sealing the grease.
In this kind of idler pulley, when the pulley body 11 is rotated under torque from the belt, the outer race 12b of the ball bearing 12 fitted therein rotates with the pulley body 11.
In idler pulleys of the type described above, it is common practice to provide an arrangement in which the load center of a belt load coincides with the bearing center line Y of the ball bearing 12 and in which the pulley rotation axis Z coincides with the fixed axis X. This arrangement, which is intended to avoid undesirable effects on the ball bearing 12 as the belt load would otherwise act as localized load on the ball bearing 12, should be said to be a basic machine design which has heretofore been adopted. Further, the ball bearing 12 is usually a deep groove ball bearing and it is common practice not to use a preloaded bearing. This is believed to have stemmed from an anxiety about undesirable effects brought about by the use of bearings under preload.
In this connection, it is to be noted that the use of an idler pulley described above in cold time is sometimes attended by an abnormal sound (hoot sound). This abnormal sound in cold time, the so-called cold time abnormal sound, does not always occur in the market but, depending on temperature, etc., it occurs in restricted areas; For example, in Japan, it occurs in Hokkaido. Further, it occurs only for a short time (about 1 minute at most) from the time after the engine is started; thenceforth it never occurs. The cold time abnormal sound has such complicated properties and is difficult to reproduce; therefore, the cause has not been elucidated. Furthermore, idler pulleys used in automobiles and the like operate under high temperature high speed conditions, and their durability is one of the important characteristics and hence counter measures which would lead to a decrease in durability cannot be taken. For such reason, at present, there has been provided no effective means to solve the problem of cold time abnormal sound in idler pulleys. Heretofore, the use of grease having superior low temperature characteristics (which grease will form oil films evenly on areas of contact between the rolling elements and the raceway surfaces of the inner and outer race in cold time) in bearings as a measure against cold time abnormal sound has been taken into consideration. This measure aims at suppressing the occurrence of cold time abnormal sound by enhancing the lubricating performance of the grease in cold time, and a substantial effect can be expected. However, since the viscosity of grease decreases, the
REFERENCES:
patent: 3918277 (1975-11-01), Nakk
patent: 4265133 (1981-05-01), Van Der Meulen et al.
patent: 4917655 (1990-04-01), Martin
patent: 4938732 (1990-07-01), Krude
Fukuwaka Masao
Kato Yoshio
Koremoto Takahiro
Mizutani Tsutomu
Muranaka Masahiro
NTN Corporation
Schoeppel Roger J.
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