Improved inverted tooth chain

Abstract: A chain constructed of alternating groups (12) of fine blanked articulating links (14) and sets (16) of guide and connecting links (18,20). The sets and groups of links are joined by pivot means (48), journaled in smooth walled openings in the articulating links and press-fit into the openings in the guide and connecting links. The articulating links (14) are of the silent variety with a pair of toes (24) spaced by a crotch with the defining flanks (26,28) of the toes being adaptable for drivingly contacting the teeth of sprockets. To provide the smooth walled openings in the articulating links, these links are fine blanked as opposed to being conventionally blanked.

Description: This invention relates to inverted tooth chain especially adapted for automotive use, such as for timing chains; the chain, however is adaptable for other power transmission applications. Inverted tooth chains are well known in the art and many are especially adaptable for automotive use, such as for timing chains. Many timing chains are of the roller chain construction, as well known in the art. These chains mesh with sprockets with their rollers drivingly engaging the flanks of the sprocket teeth. Other chains for the same purpose are of the "silent" or inverted tooth variety, comprising a plurality of interleaved sets of links, each set of links being joined to the next adjacent set of links by a pivot means, such, for example, a round pin or a multiple piece rocker joint. The various types of pivot means are well known in the chain art and need no further description. The links of silent or inverted tooth chain are constructed with a body having a pair of spaced openings to receive the pivot means, and a pair of depending toes separated by a crotch. The toes are defined by diverging inside and outside flanks, the flanks usually drivingly contacting the teeth of the sprockets in the drive in which the chain is used. Guide links flanking the outsides of the links of the chain or located centrally thereof serve to maintain meshing engagement of the chain with the sprockets. The guide links are placed are shaped to avoid any driving contact with the sprocket teeth. In any event, the pitch of all links is the same. U.S. Patent No. 4,463,550 shows a silent chain having a pair of guide links non-rotatively fastened to the ends of a pair of pins. A central link pack devoid of bushings is provided and directly engages the pins. The links in the central link pack are characterized by having a pair of depending toes separated by a crotch. A pair of articulating link packs are rotatively connected to one of the pins on either side of the central link pack. Bushings are provided in the articulating packs. The links in the articulating link packs are characterized by having a pair of depending toes separated by a crotch. Customarily, the links of a chain are stamped or blanked at relatively high rates of speed from metal strip and later treated to insure the proper hardness of the links. The pivot means can be cord wood cut from an extruded metal shape and then hardened to improve the wearing characteristics of the part and thus the finished chain. The chain is assembled in a continuous length with specific lengths being "broken" out, and the ends of each length being joined to complete the loop. Various methods are used to maintain the sets of links in the assembled chain, as for example upsetting or peening over of a joint members at their ends, such methods being well known in the chain art. When the links are customarily blanked, they are literally sheared from the strip material and the openings therethrough which receive the joint means, are likewise produced by the shearing action, resulting in an openings with walls that have a rough surface. Relative rotation between a joint member and such an opening causes the pin to rapidly wear, thus reducing the life of the chain. An improved inverted tooth chain having an improved weight/life ratio will be described; the chain has fewer ports that the usual chains for the same application, and provides improved bearing areas for the joint means resulting in better wear characteristics than prior art chains. The chain of this invention comprises alternating groups or sets of inverted tooth links and sets or groups of guide links and at least one connecting link, the inverted tooth links are articulating links and provide smooth walled openings for in which the pivot means is journaled. The articulating links are preferably double the thickness of the guide links or the connecting link, and are fine blanked, to provide the smooth walled openings to receive the joint means. The connecting and guide links are conventionally blanked. The pivot means, as indicated heretofore, are journaled for rotation in the articulating link openings and are press fit into openings in the guide links and the connecting links, so as not rotate with respect to those links. The inverted tooth articulating links, have diverging flanks defining their toes which drivingly contact the teeth of sprockets with which the chain meshes. Because of the arrangement of the links in the chain of this invention, bending of the pivot means is avoided, the links providing a balanced load distribution on the joint means counteracting joint deformation. In order that the invention may be well understood there will now be described two embodiments thereof, given by way of example, reference being made to the accompanying drawings, in which: Fig. 1 is a side view of a portion of a chain embodying the invention and showing in broken lines a sprocket with which the chain meshes; Fig. 2 is a top view of the portion of chain constructed as in Fig. 1, with parts broken away; Fig. 3 is an elevational view of an articulating link as used in the chain portion of Figs. 1 and 2; Fig. 4 is a view of a typical guide link as used in the chain portion of Fig. 1; Fig. 5 is an elevational view of a connecting link as used in the chain of Figs. 1 and 2; and Fig. 6 is a top view of a portion of an alternative chain embodying the invention. Referring first to Figs. 1 and 2, a chain 10 is constructed of a plurality of sets or groups 12 of articulating links 14 alternating with groups or sets 16 of links comprising a pair of guide links 18 which flank the outside of the chain 10 and a connecting link 20 which is centrally disposed between the links 14. Each link 14 has a body 22 and a pair of toes 24, each defined by an inside flank 26 and an outside flank 28. The flanks 26 and 28 can be straight or curved, so long as the flanks drivingly engage the teeth of a sprocket 30 in the overall drive arrangement. Each link 14 also is fine blanked with a pair of spaced openings 32, each defined by a smooth wall 34. Each guide link 18 has a body 36 and a pair of spaced openings 38 therein. Because these links are conventionally blanked, each wall 40 defining an opening 38 is somewhat rough, indicating that the opening 38 was formed primarily by a shearing action. Each connecting link 20 has a body 42 and a pair of spaced openings 44 therein. These links are conventionally blanked, and thus each wall 46 defining an opening 44 is somewhat rough, indicating that the opening was formed primarily by a shearing action. Each connecting link 20 is so shaped that it will not drivingly engage the teeth of a sprocket in the drive arrangement. Pivot means 48, shown as round pins, are used to connect the alternate sets or groups of links, and permit the articulation of the chain about the pivot means. Each pin means 48 is journalled in the openings 32 of each pair of links of the sets 12 of links 14 such that relative rotation between the links 14 and the pins 48 occurs. The pin which is journalled in the links 14 is a press fit in the opening 44 in the adjacent connecting link and also in the openings 38 in the guide links of the set of guide and connecting links, so that no relative rotation between the pin and the guide and connecting links occurs. The chain 50 illustrated in Fig. 6 differs from that illustrated in Figs. 1 and 2 in that the articulating sets 52 of links 14 comprise three links, with a connecting link 20 between each adjacent link and guide links 18 flanking the sides of the chain. The width of the chain can be changed so long as a connecting link 20 is placed between each adjacent articulating link 14. As can be appreciated, the bearing area for each pin, i.e., the area of the walls defining the openings in the articulating links, provides an improved load distribution on the pivot means counteracting any deformation of the pin and, also, because of the improved journal provided by the smooth walls of the openings in the articulating links, results in better wear characteristics than in the ordinary chain of the prior art. The central connecting links are so shaped to avoid all contact with sprocket teeth and do not therefore load relatively high area pressure on the sprocket teeth, resulting in longer sprocket life because of the reduction in wear caused by the absence of impact with the connecting links.

Claims: A chain (10) having sets (12, 16; 52, 16) of interlaced links (14, 16, 18) joined by pivot means (48) passing through aligned openings (32, 38, 44) in the sets of links, alternate sets (12; 52) of links (14) being articulating links (14), the other sets (16) of links (18, 20) being guide (18) and connecting (20) links, the guide links (18) flanking the outside of the articulating links (14), characterized by the openings (32) of the articulating links (14) being fine blanked to present smooth walls (34) and permitting relative movement between the pivot means (48) and the articulating links (14), the articulating links (14) having a plurality of diverging flanks (26, 28) defined by a pair of toes (24) spaced by a crotch and being constructed to drivingly engage teeth of a sprocket (30), the connecting links (20) being so shaped as to avoid contact with the sprocket teeth, the pivot means (48) being press-fit into the openings (38, 44) in the guide and connecting links (18, 20). A chain as claimed in claim 1, wherein each articulating link (14) is of the order of two times the thickness of each guide link (18) and connecting link (20) A chain as claimed in claim 1 or claim 2, wherein each set (12; 52) of articulating links (14) comprises at least two links (14). A chain as claimed in any of the preceding claims, wherein the pitch of the articulating links (14) is the same as the pitch of the guide links (18) and connecting links (20). A chain as claimed in any of the preceding claims, wherein the openings (38, 44) in the guide and connecting links (18, 20) snugly receive the pivot means (48) in such a manner as to avoid relative rotation of the pivot means (48) and the guide and connecting links (18, 20).

Inventors: REBER REINER F, REBER, REINER F.
Applicants: BORG WARNER AUTOMOTIVE, BORG-WARNER AUTOMOTIVE TRANSMISSION AND ENGINE COMPONENTS CORPORATION
Application year: 1989
Main classification: F16G13
IPC codes: F16G13