BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view, partly in cross-section, of a part of the oil-free chain in accordance with a first embodiment of the invention;
FIG. 2 is a perspective view, partly in cross-section, illustrating the manner in which an inner link and an outer link of the chain are connected;
FIG. 3 is an enlarge cross-sectional view of a part of the oil-free chain shown in FIG. 1, including an enlarged auxiliary view showing details of overlapping, mutually facing, surfaces of the inner and outer plates of the chain;
FIG. 4 is a cross-sectional view of the chain of the first embodiment, showing dimensions of parts of the chain;
FIG. 5 is a plan view of the chain, partly in section, showing the chain in tension, and including an enlarge auxiliary view illustrating details of a part of the connection between the inner and outer links of the chain;
FIG. 6 is a plan view of the chain, partly in section, including two enlarge auxiliary views, showing an inner link biased in a widthwise direction;
FIG. 7 is a perspective view, partly in section, showing a portion of a chain according to a second embodiment of the invention; and
FIG. 8 is a cross-sectional view of a part of the chain of FIG. 7, including an enlarge auxiliary view showing details of overlapping, mutually facing, surfaces of the inner and outer plates of the chain.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
As shown in FIGS. 1 and 3, a wear resistant and heat resistant, oil-free conveyor chain 100 according to a first embodiment of the invention, includes an inner link 140 and outer links 170. In the inner link 140, the ends of a pair of bushings 130, on which rollers 120 fit loosely, are press-fit into holes 111 in a pair of spaced inner plates 110. In the outer links 170, both ends of a pair of connecting pins 160 are press-fit into holes 151 of a pair of spaced outer plates 150.
The inner and outer links 140 are connected by virtue of the fact that each connecting pin 160 loosely fits into a bushing 130. Lubricating oil is sealed between the bushing 130 and the connecting pin 160.
As shown in FIGS. 2 and 3, bushing supporting bores 152 are formed on the inner side surfaces 153 the outer plates 150. These bushing supporting bores are open to their full diameter at the inside-facing surfaces of the outer plates, and each bore 152 is coaxial with a pin-receiving hole 151 formed in an outer plate. The ends of each bushing 130 protrude from the outer side surfaces 112 of the inner plates 110, and are received in, and supported by the bushing supporting bores 152.
As shown in the auxiliary enlargement which is part of FIG. 3, the overlapping parts of the inner surface 153 of the outer plate 150, and the outer surface 112 of the inner plate 110, have a matte-finish forming rough surfaces 153a and 112a respectively, which cooperate to form a labyrinth structure L2.
As shown in FIG. 4, the inner diameter Wj of the bushing supporting bore 152, the inner diameter Wbi of the bushing 130, the outer diameter Wbo of the bushing 130, and the outer diameter Wp of the connecting pin 160, are formed so that they satisfy the relationship Wj−Wbo>Wbi−Wp.
FIG. 4 also shows that the bushing 130 protrudes from the outer surface of inner plate 110 by an amount Db, which exceeds the depth Dj of the bushing support bore 152. That is, Dj<Db.
The depth Dj of the bushing supporting bore 152, the amount Db of protrusion of the bushing 130 from the outer side surface of the inner plate 110, the spacing Do between the inside faces of the plates of the outer link 170, and the spacing Di of the outside faces of the plates of the inner link 140, are formed so that they satisfy the relationship Dj+Do<Di+2Db<2Dj+Do.
As shown in FIG. 3, in the chain 100, since the protruding ends of each bushing 130 extend into the bushing supporting bores 152 in the inner sides 153 of the outer plates 150, a labyrinth structure L1 is formed between an end portion of each bushing 130 and the inner surface of a bushing supporting bore 152. This labyrinth structure prevents leakage of lubricating oil due to inertial forces generated during circulating travel of the chain. The sealed lubricating oil, guided by an inner circumferential surface of the bushing 130 tends to ooze outward toward the outer plates 150. However, the bent lubricant leakage path resulting from the cooperative relationship between the protruding ends of the bushings and the bushing supporting bores resists leakage of oil to the outside. At the same time, the labyrinth structure prevents the invasion of dust from the outside.
The chain 100 does not require additional seal members compressed between the inner plates 110 and the outer plates 150. Therefore, the chain can flex more smoothly than a conventional seal chain, and has the additional advantage that it has smaller number of the parts so that assembly of the chain is less expensive, and connection and disconnection of the chain are made easier.
Moreover, surface finishing to reduced the roughness of the plates in order to prevent wear of seal members is not needed. The avoidance of surface finishing also contributes to the low production cost of the chain.
The labyrinth structure L2, formed by the closely facing rough surfaces 153a and 112a, shown in FIG. 3, further improves the sealing effect of the chain, both preventing lubricating oil from leaking out, and preventing invasion of dust from outside the chain.
When the relationship Wj−Wbo>Wbi−Wp is satisfied, as shown the auxiliary enlargement of a portion of FIG. 5, even if a high degree of tension in the chain biases an inner link with respect to an outer link, the inner circumferential surface 131 (FIG. 3) of the bushing and the outer circumferential surface of the connecting pin 160 (FIG. 3) come into contact with each other before the outer circumferential surface of the end of a bushing can contact the inner circumferential surface 152a (FIG. 3) of a bushing supporting bore 152. Contact between the outer circumferential surface of an end portion of a bushing and the inner circumferential surface of a bushing supporting bore is entirely prevented. As a result, even if the supply of lubricating oil is in adequate, generation of metal powder by wear due to sliding contact between the outer circumferential surface of end portion of a bushing and the inner circumferential surface of a bushing supporting bore is avoided, and metal powder does not invade the space between the connecting pin and the bushing to cause abrasion, abnormal wear, and undesirable wear elongation of the chain.
Referring to FIGS. 3, 4 and 6, if the relationship Dj<Db is satisfied, even if an inner link 140 becomes skewed, pivoted or biased with respect to an outer link 170, an end surface 133 (FIG. 3) of the bushing and a bottom surface 152b (FIG. 3) of a bushing supporting bore 152 come into contact with each other. The end of the bushing and the bottom of the bore 152 have relatively small sliding are as compared to the are as of the mutually facing surfaces of the inner and outer plates. Because the ends of the bushings come into contact with the bottoms of the bores 152 before the inner and outer plates can come together, sliding contact between the mutually facing surfaces of the inner and outer plates is prevented as shown in FIG. 6. Thus, smooth bending of the chain over a long period of time can be realized.
Again referring to FIGS. 3, 4 and 6, when the relationship Dj+Do<Di+2Db<2Dj+Do is satisfied. even if an inner link 140 becomes skewed, pivoted or biased in a widthwise direction with respect to an outer link 170, the protruding end of the bushing 130 cannot separate from the bushing supporting bore 152. Therefore, leakage of lubricating oil and invasion of external dust can be more reliably prevented during operation of the chain, and wear between the outer circumferential surface 161 of the connecting pin 160 and the inner circumferential surface 131 of the bushing 130 can be reduced over a long period of time so that wear elongation of the chain can be prevented.
In the second embodiment of the invention, shown in FIGS. 7 and 8, a wear-resistant and heat-resistant, oil-free chain 200 includes an inner link 240 and an outer link 270. In the inner link 240, rollers 220 are loosely fitted on bushings 230. The ends of each bushing 230 are press-fit into holes 211 of a pair of inner plates 210. In the outer link 270, both ends of a pair of connecting pins 260 are press-fit into holes 251 of a pair of outer plates 250.
The inner links 240 and the outer links 270 are connected by virtue of the fact that each connecting pin 260 extends through a bushing 230. Lubricating oil is sealed between each bushing 230 and the connecting pin 260 extending through the bushing.
As shown in FIGS. 7 and 8, bushing support bores 252 are formed on the inner side surfaces 253 the outer plates 250. The bores are open to their full diameter at the inside-facing surfaces of the outer plates, and each bore 252 is coaxial with a pin-receiving hole 251 formed in an outer plate. The ends of each bushing 230 protrude from the outer side surfaces 212 of the inner plates 210, and are received in, and supported by, the bushing supporting bores 252.
As shown in the auxiliary enlargement which is part of FIG. 8, the overlapping parts of the inner surface 253 of the outer plate 250, and the outer surface 212 of the inner plate 210, both have a matte-finish, forming rough surfaces 253a and 212a respectively, which cooperate to form a labyrinth structure L4. As shown in the main part of FIG. 8, a D-shaped oil retaining groove 262 is provided on the outer circumferential surface of the connecting pin 260.
As in the first embodiment, the inner diameter Wj of the bushing supporting bore 252, the inner diameter Wbi of the bushing 230, the outer diameter Wbo of the bushing 230, and the outer diameter Wp of the connecting pin 260 satisfy the relationship Wj−Wbo>Wbi−Wp.
Moreover, as in the first embodiment, the bushing 230 protrudes from the outer surface 212 of inner plate 210 by an amount Db, which exceeds the depth Dj of the bushing support bore 252. That is, Dj<Db.
As in the first embodiment, the depth Dj of the bushing supporting bore 252, the amount Db of protrusion of the bushing 230 from the outer side surface of the inner plate 210, the spacing Do between the inside faces of the plates of the outer link 270, and the spacing Di of the outside faces of the plates of the inner link 120, are formed so that they satisfy the relationship Dj+Do<Di+2Db<2Dj+Do.
As shown in FIG. 8, in the chain according to the second embodiment of the invention, since the protruding ends of each bushings 230 extend into the bushing supporting bores 252 in the inner sides 253 of the outer plates 250, a labyrinth structure L3 is formed between an end portion of each bushing 230 and the inner surface of a bushing supporting bore 252. This labyrinth structure prevents leakage of lubricating oil due to inertial forces generated during circulating travel of the chain. The sealed lubricating oil, guided by an inner circumferential surface of the bushing 230 tends to ooze outward toward the outer plates 250. However, the bent lubricant leakage path resulting from the cooperative relationship between the protruding ends of the bushings and the bushing supporting bores prevents leakage of oil to the outside. At the same time, the labyrinth structure prevents the invasion of dust from the outside.
The chain 200 does not require additional seal members compressed between the inner plates 210 and the outer plates 250. Therefore, the chain can flex more smoothly than a conventional seal chain, and has the additional advantage that it has smaller number of the parts so that assembly of the chain is less expensive, and connection and disconnection of the chain are made easier.
Moreover, surface finishing to reduced the roughness of the plates in order to prevent wear of seal members is not needed. The avoidance of surface finishing also contributes to the low production cost of the chain.
In the second embodiment, the oil retaining groove 262 formed on the outer surface of the connecting pin holds lubricating oil for lubricating the mutually sliding inner circumferential surface 231 of the bushing 230 and outer circumferential surface 261 of the connecting pin 260.
The additional lubricating oil capacity afforded by the groove 262 ensures that sliding wear between the outer circumferential surface 261 of the connecting pin 260 and the inner circumferential surface 231 of the bushing 230 can be reduced over a long period of time so that wear elongation of the chain can be prevented.
The labyrinth structure L4, formed by the closely facing rough surfaces 253a and 212a, shown in the auxiliary enlargement of part of FIG. 8, further improve the sealing effect of the chain, both preventing lubricating oil from leaking out, and preventing invasion of dust from the outside.
As in the case of the first embodiment, since the relationship Wj−Wbo>Wbi−Wp is satisfied, contact between the outer circumferential surface of an end portion of a bushing and the inner circumferential surface of a bushing supporting bore is entirely prevented. As a result, even if the supply of lubricating oil is inadequate, generation of metal powder by wear due to sliding contact between the outer circumferential surface of end portion of a bushing and the inner circumferential surface of a bushing supporting bore is avoided, and metal powder does not invade the space between the connecting pin and the bushing to cause abrasion, abnormal wear, and undesirable wear elongation of the chain.
As in the first embodiment, since the relationship Dj<Db is satisfied, even if an inner link 240 becomes skewed, pivoted or biased with respect to an outer link 270, an end surface 233 (FIG. 8) of the bushing and a bottom surface 252b (FIG. 8) of a bushing supporting bore 252 come into contact with each other. The end of the bushing and the bottom of the bore 252 have relatively small sliding are as compared to the are as of the mutually facing surfaces of the inner and outer plates. Because the ends of the bushings come into contact with the bottoms of the bores 252 before the inner and outer plates can come together, sliding contact between the mutually facing surfaces of the inner and outer plates is prevented. Thus, smooth bending of the chain over a long period of time can be realized.
In the second embodiment, as in the first embodiment, the relationship Dj+Do<Di+2Db<2Dj+Do is also satisfied. As a result, even if an inner link 240 becomes skewed, pivoted or biased in a widthwise direction with respect to an outer link 270, the protruding end of the bushing 230 cannot separate from the bushing supporting bore 252. Therefore, leakage of lubricating oil and invasion of external dust can be more reliably prevented during operation of the chain, and wear between the outer circumferential surface 261 of the connecting pin 260 and the inner circumferential surface 231 of the bushing 230 can be reduced over a long period of time so that wear elongation of the chain can be prevented.
The invention may be embodied in a roller chain or a rollerless bushing chain. However, in a roller chain, engagement between the chain and a sprocket is smoother and less wear occurs. Thus, the roller chain is preferable.
Various modifications can be made to the chains according to the invention. For example, the oil-retaining grooves in the connecting pins can be annular grooves formed in the outer surfaces of the connecting pins. However, the D-shaped groove is preferable since it enables a large amount of lubricating oil to be sealed within the chain while maintaining the strength of the connecting pin.
The shape of the bushing supporting bore is preferably circular, but any of various alternative shapes, such as a regular polygon, can be adopted.
Various other modifications can be made to the embodiments described without departing from the scope of the invention as defined in the following claims.
Patent Application
20080076613
