Conveyor chain having a roller housing cylindrical rollers therein

A conveyor chain having a hollow roller housing (15), an annular series of cylindrical rollers (14A and 14B) therein providing rotation of the hollow roller on an internal bushing (13). Alternate cylindrical rollers (14A) have a pair of cylindrical roller separating retaining rings (17) rotatably fitted over both ends. Intermediate cylindrical rollers (14B) have no cylindrical roller separating retaining rings (17). The retaining rings (17) on the alternate rollers (14A) engage the intermediate cylindrical rollers (14B). The cylindrical bearing surfaces (13A, 15A) are sandwiched between the retaining rings at each end of the rollers (14A) and project toward the outer circumferential surfaces of the cylindrical rollers (14A and 14B). The roller (15) and the bushing (13) have recessed surfaces (15A and 13A) which are spaced from the outer and inner circumferential surfaces of the retaining rings (17).

FIELD OF THE INVENTION 
The present invention relates to a roller chain used as a conveyor chain. 
BACKGROUND OF THE INVENTION 
In the past, in a chain having a hollow roller housing cylindrical rollers 
therein used as a conveyor chain, a number of cylindrical rollers are 
disposed with peripheral surfaces circumscribed each other between the 
outer peripheral surface of a bushing fitted over a connecting pin and the 
inner peripheral surface of the roller, and the outer peripheral surface 
of the roller is slightly projected from an upper side and a lower side of 
a chain link, as disclosed in Japanese Patent Application Laid-Open No. 
Hei 4-78523. 
In the above-described conventional conveyor chain, a number of cylindrical 
rollers 3 circumscribe on the outer peripheral surface of a bushing 1 and 
inscribe the inner peripheral surface of a hollow roller 2 for rolling 
while engaging each other, as shown in FIG. 4. When the hollow roller 2 
rotates clockwise relative to the bushing 1 in a direction of arrow, the 
respective cylindrical rollers roll clockwise. Therefore, in the 
peripheral surface portion in which the cylindrical rollers 3 engage the 
adjacent rollers, their rolling directions are opposed to each other, so 
that when the lubricating function lowers due to the deterioration or 
leak-out of grease sealed for lubrication of the cylindrical rollers, the 
frictional resistance increases at the engaging peripheral surface 
portions between the adjacent cylindrical rollers and such friction may 
generate a defective rolling. As a result, the hollow roller 2 is not 
rotated smoothly, and finally, burning caused by frictional heat occurs to 
an extent that the hollow roller cannot be rotated. 
SUMMARY OF THE INVENTION 
The present invention solves the aforementioned problem by the arrangement 
wherein a pair of opposed thrust bearing plates are interposed between 
opposed inner surfaces of inner plates of the chain link and both end 
surfaces of the hollow roller, and both end surfaces of cylindrical 
rollers having an axis parallel with the connecting pin. Furthermore, 
selected cylindrical rollers have a pair of cylindrical roller separating 
retaining rings rotatably fitted over the cylindrical roller surface at 
both ends between said pair of thrust bearing plates. Other cylindrical 
rollers having no cylindrical roller separating retaining rings alternate 
with the selected cylindrical rollers in a series surrounding the outer 
periphery of a bushing fitted over said connecting pin, said cylindrical 
roller separating retaining rings engaging the outer peripheral surfaces 
of the cylindrical rollers having no cylindrical roller separating 
retaining rings. Between said pair of cylindrical roller separating 
retaining rings, the series of cylindrical rollers is sandwiched between 
the outer peripheral surface of said bushing and the inner peripheral 
surface of the roller. 
The cylindrical roller separating retaining rings fitted over both ends of 
the cylindrical rollers engage the outer peripheral surfaces of both ends 
of the cylindrical rollers having no roller separating retaining rings to 
retain a separated spacing between the cylindrical rollers in the series, 
avoiding direct contact of the cylindrical surfaces of the adjacent 
cylindrical rollers which roll in the direction opposed to each other. 
Further, since the cylindrical roller separating retaining rings are 
rotatably fitted over both ends of the cylindrical rollers, they rotate 
irrespective of the rolling direction of the cylindrical rollers and are 
engaged with the outer peripheral surfaces of both ends of the adjacent 
cylindrical rollers in the series.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 is a view of a conveyor chain according to the present invention, 
and FIG. 2 is a longitudinal sectional view (taken on line 2--2 of FIG. 
3). FIG. 3 is a transverse sectional view. In the conveyor chain, a pair 
of outer link plates 10 and inner link plates 11, 11 are connected in a 
chain-like form as a chain link by means of a connecting pin 12. The link 
plates are separated to leave a space therebetween to receive a hollow 
roller 15. The connecting pin 12 has both ends inserted into a bushing 13 
which is press-fitted into a connecting pin inserting hole of the inner 
link plates 11, 11. The roller 15 is rotatably fitted over the bushing 13 
by a series of cylindrical rollers 14A and 14B. 
Two annular thrust bearing plates 16, 16 are interposed between the opposed 
inner surfaces of the inner link plates 11, 11 and the end surfaces of the 
roller 15. 
The cylindrical rollers 14A and 14B form an annular series surrounding the 
bushing 13 and have their rotary axes parallel with the axis of the 
connecting pin 12 between the pair of thrust bearing plates 16, 16. 
Cylindrical rollers 14A have a pair of cylindrical roller separating 
retaining rings 17, 17 slidably mounted, one at each end of the 
cylindrical surface, for both circumferential and axial displacement 
relative to the cylindrical roller 14A. Cylindrical rollers 14B have no 
cylindrical roller separating retaining rings. The rollers 14A and 14B 
alternate in the annular series. Outer peripheral surfaces of the 
cylindrical roller separating retaining rings 17, 17 are not in contact 
with either the outer peripheral surface of the bushing 13 or the inner 
peripheral surface of the roller 15. To this end, the bushing 13 has a 
bearing surface portion 13A to engage the cylindrical rollers 14A and 14B 
and recessed portions 13B extending beyond said bearing surface portion 
13A to be spaced inwardly from the rings 17 on the rollers 14A. Likewise, 
the hollow roller 15 has a bearing surface 15A to engage the annular 
series of rollers 14A and 14B and recessed portions 15B extending beyond 
said surface portion 15A to be spaced outwardly from the rings 17 on the 
rollers 14A. The cylindrical roller bearing surfaces 13A and 15A have a 
width to be sandwiched between the confronting surfaces of the pair of 
cylindrical roller separating retaining rings 17, 17. In this way, the 
rings 17 may float between the bearing plates 16 and the ends of the 
bearing portions 13A and 15A. 
Accordingly, the cylindrical rollers 14A and 14B in the annular series are 
separated from each other by the cylindrical roller separating retaining 
rings 17, 17 so that the cylindrical rollers 14A and 14B cannot possibly 
directly engage one another. Further, since the cylindrical roller 
separating retaining rings 17, 17 are rotatably fitted over both ends of 
the cylindrical rollers 14A, even if the cylindrical roller separating 
retaining rings 17, 17 engage circumscribed on the outer peripheral 
surfaces at both ends of the adjacent cylindrical rollers 14B, they can be 
freely rotated in the rotating direction without being restrained by the 
rotating direction of the cylindrical rollers 14A. Further, since the 
width of the circumscribed peripheral surface of the cylindrical roller 
separating retaining rings 17, 17 is extremely small as compared with the 
case where the peripheral surfaces of the cylindrical rollers 14 are 
directly engaged, there is less frictional rotational resistance to impede 
the rotation of the cylindrical rollers 14A and 14B in the same direction. 
According to the present invention, since all of the cylindrical rollers 
14A and 14B interposed in series between the outer peripheral bearing 
surface 13A of the 13 bushing and the inner peripheral bearing surface 15A 
of the roller 15 can be rolled in the same direction without direct 
engagement between the cylindrical rollers by reason of the separating 
retaining rings 17, there is no rolling resistance between the cylindrical 
rollers, and smooth rolling can be retained. Further, since the 
cylindrical roller separating retaining rings 17 are rotatable on both 
ends of the cylindrical rollers 14A, even if the cylindrical roller 
separating retaining rings 17 engage the cylindrical rollers 14B, the 
width of the cylindrical roller separating retaining rings is extremely 
small as compared with the length of the cylindrical rollers 14A and 14B 
so that the rolling resistance is minor, and it is unlikely to cause 
defective rolling of the cylindrical rollers, and the durability of the 
conveyer chain also increases. 
While a particular embodiment of the invention has been herein illustrated 
and described, it is not intended to limit the invention to such 
disclosures, but changes and modifications may be made therein and thereto 
within the scope of the following claims.