BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view, partly in cross-section, of a chain used in a chain transmission according to a first embodiment of the invention;
FIG. 2 is a front elevational view of a sprocket used with the chain of FIG. 1;
FIG. 3 is a schematic side elevational view illustrating the relationship between the chain of FIG. 1 and the sprocket of FIG. 2;
FIG. 4
a is a schematic side elevational view illustrating the meshing of a link plate with the sprocket;
FIG. 4
b is schematic diagram illustrating the polygonal movement of the chain;
FIG. 5 is schematic side elevational view illustrating the relationship between a chain and sprocket in a transmission according to a second embodiment of the invention;
FIG. 6
a a schematic side elevational view illustrating the meshing of a link plate with the sprocket in the second embodiment;
FIG. 6
b is schematic diagram illustrating the polygonal movement of the chain in the second embodiment; and
FIG. 7 is a plan view of a portion of a conventional composite chain.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The chain transmission according to the first embodiment of the invention comprises a composite chain and a set of sprockets. In the first embodiment, each of the link plates is formed with a pair of teeth.
As shown in FIG. 1, the chain 1 comprises outer links 5 and inner links 10 arranged in alternating relationship along the length of the chain. Each outer link comprises a pair of opposite link plates 2 connected by a pair of connecting pins 4. The ends of the connecting pins are fitted into pin holes 3 in the outer link plates 2. Each inner link 10 comprises a pair of inner link plates 6, connected by bushings 9 which are fitted into bushing holes 9 in the inner link plates. Rollers 8 are situated on the bushings between the inner link plates, and are rotatable on the bushings. Pins of the outer links extend through bushings of the inner links. The pins and bushings connect the inner and outer links in alternating relationship to produce a transmission chain in the form of an endless loop. The pins are rotatable in the bushings so that the links are articulable relative to one another, thereby allowing the chain to flex so that it can be wound around a sprocket.
As shown in FIGS. 3 and 4a, an outer link plate 2 and an inner link plate 6 have identical contours. Each is bifurcated so that it has a pair of teeth 11. The teeth have outer flanks 11b, and inner flanks 11a.
As shown in FIG. 2, a sprocket 12 of the transmission comprises three sets of sprocket teeth. First and second sets of sprocket teeth 13 are disposed on opposite sides of a third set of sprocket teeth 14, and the diameter of the third set of sprocket teeth is greater than the diameter of the first and second sets. When the chain 1 is in mesh with the sprocket, the rollers 8 mesh with teeth 14, fitting into the gaps between the teeth, the teeth 11 of the link plates on one side of the chain mesh with one set of sprocket teeth 13, and the teeth 11 of the link plates on the other side of the chain mesh with the other set of sprocket teeth 13. In a typical chain transmission, the chain will be in mesh with a driving sprocket and with one or more driven sprockets. The teeth of the outer link plates 2 and the teeth of the inner link plates 6 mesh in exactly the same way with sprocket teeth 13.
Referring to FIGS. 3 and 4a, as the chain 1 approaches the sprocket, an inner, or rear, flank 11a of a forward tooth 11 of a link plate 2 comes into contact with a first sprocket tooth 13, and the inner flank 11a slides along the sprocket tooth as the forward tooth moves toward the tooth gap bottom 13a. The forward tooth of each of the link plates 6 comes into contact with the sprocket teeth 13 in the same way that the forward tooth of each of the link plates 2 comes into contact with the sprocket teeth. As the forward tooth moves toward the tooth gap bottom, a roller 8, which is adjacent the rear tooth of the link plate, moves toward the intermediate sprocket, into a space between two adjacent sprocket teeth 14 where the roller becomes seated.
When the roller 8 is seated, the inner flank 11a of the forward tooth 11 moves away from the sprocket tooth 13 so that, when the roller adjacent the rear tooth of the link plate becomes seated, neither the inner nor outer flanks of the teeth 11 of the link plate are in contact with the sprocket teeth 13. As shown in FIG. 3, clearances are formed between both outer flanks 11b and the sprocket teeth 13.
Because at the start of meshing, the inner flank of a link plate tooth comes into contact with a sprocket tooth 11, noise at the start of meshing is suppressed. Noise on meshing of the roller 8 is also reduced, and, at the same time wear of the sprocket teeth 14 is suppressed. The surface pressure between the connecting pins and the bushings 9 is small, and pivotal movements of the links 5 and 10 are carried out smoothly. Thus, wear elongation of the chain can be suppressed.
As the chain is wound around the sprocket it moves up and down in a range δ1 as a result of polygonal movement of the chain as shown schematically in simplified form in FIG. 4b, where 2a represents the back of an outer link plate 2. However, since the inner flanks 11a of the teeth 11 of the link plates come into contact with sprocket teeth 13 at the start of meshing engagement, engagement noise is suppressed.
As the rollers 8 become seated, the teeth 11 of the link plates 2 and 6 are spaced away from the sprocket teeth 13. Thus the load on the chain is not applied to the teeth 11, and the fatigue strength of the chain is the same as that of the roller chain.
The number of link plates 2 and 6 in the direction of the width of the chain 1 is only four. Thus, the chain is lighter in weight than the conventional composite chain, and a cost reduction can be achieved.
In the second embodiment of the invention, as shown in FIGS. 5 and 6, each link plate has a single angle-shaped tooth formed thereon.
The chain 21, shown in FIG. 5, is similar to the chain in FIG. 3 in that it comprises outer links and inner links arranged in alternating relationship along the length of the chain. Each outer link comprises a pair of opposite link plates 22 connected by a pair of connecting pins 23. The ends of the connecting pins are fitted into pin holes in the outer link plates 22. Each inner link comprises a pair of inner link plates 24, connected by bushings which are fitted into bushing holes in the inner link plates. Rollers 25 are situated on the bushings between the inner link plates, and are rotatable on the bushings. Pins of the outer links extend through bushings of the inner links. The pins and bushings connect the inner and outer links in alternating relationship to produce a transmission chain in the form of an endless loop. The pins are rotatable in the bushings so that the links are articulable relative to one another, thereby allowing the chain to flex so that it can be wound around a sprocket.
As shown in FIGS. 5 and 6a, the outer link plates 22 of the outer link and the inner link plates 24 of the inner link have identical contours, and each has a single, angle-shaped tooth 26 protruding from a central location between the ends of the link plate. The teeth 26 has flanks 26a.
A sprocket around which the chain 21 is wound includes central sprocket teeth 28 for meshing with rollers 25 of the chain 21, and outer sprocket teeth 27 on both sides, for meshing with the teeth 26 of the link plates. The sprocket teeth 27 and 28 have the same pitch angle, and teeth 27 are shifted by ½ the pitch angle from teeth 28. As in the first embodiment, in the transmission, the chain 21 is typically in mesh with a driving sprocket and one or more driven sprockets.
When a driving sprocket around which the chain 21 is wound is rotated, the chain 21 progresses by meshing the respective teeth 26 of the outer link plates 22 and inner link plates 24 with sprocket teeth 27. The teeth of the outer link plate 22 and the teeth of the inner link plate 24 mesh in the same way with the sprocket teeth 27.
As the chain approaches the sprocket, a rear flank 26a of a tooth 26 comes into contact with a sprocket tooth 27, as shown in FIGS. 5 and 6a. The flank 26a slides on the sprocket tooth as the link plate tooth 26 moves toward a tooth gap bottom 27a. As the link plate tooth slides on the sprocket tooth, a roller 25, adjacent the trailing end of the link plate comes into contact with a sprocket tooth 28 and enters the space between that sprocket tooth and a preceding sprocket tooth, ultimately becoming seated on the intermediate sprocket between the pair of teeth 28. As the roller 25 becomes seated, the flank 26a of tooth 26 moves away from the sprocket tooth 27, and when the roller is seated, the tooth 26 is spaced from the sprocket teeth 27 between which it is situated, the clearances being illustrated in FIG. 5.
As in the case of the first embodiment, in the second embodiment, because at the start of meshing, the inner flank of a link plate tooth comes into contact with a sprocket tooth 27, noise at the start of meshing is suppressed. Noise on meshing of the roller 25 is also reduced, and, at the same time wear of the sprocket teeth 28 is suppressed. The surface pressure between the connecting pins and the bushings is small, and pivotal movements of the inner and outer links and are carried out smoothly. Thus, wear elongation of the chain can be suppressed.
As shown schematically in FIG. 6b, when the chain 21 is wound around a sprocket, the vertical movement 62, resulting from polygonal movement of the chain, is smaller than the vertical movement δ1 in the case of the first embodiment. Chordal vibration noise due to the polygonal movement of the chain is therefore reduced, and meshing noise is also further reduced. As the rollers 25 become seated, the teeth 26 of the link plates 2 and 6 are spaced away from the sprocket teeth 27. Thus the load on the chain is not applied to the teeth 26, and the fatigue strength of the chain can be the same as that of the roller chain.
As in the case of the first embodiment, the number of link plates in the widthwise direction of the chain is only four, and consequently the chain can be made lighter in weight than the composite chain, and a cost reduction can be achieved.
It should be understood that various modifications can be made to the chain transmission described. For example, although the embodiments described utilized roller chains, the advantages of the invention can be realized in chain transmissions using rollerless bushing chains, i.e., chains in which the bushings themselves come into direct contact with sprocket teeth.
Patent Application
20080096709
