TRANSMISSION CHAIN WITH PIVOT PINS AND INTERMEDIATE PIECES WITH ROLLING CONTACT ACTION

Abstract: Transmission chain for a cone pulley drive, with intercoup­ led links (2a...2c) and pivot pins (4a, 4b) inserted through link openings of which the end surfaces (18a, 18b) cooperate with the cone surfaces, cooperating where between each pivot pin (4a, 4b), on the one hand, and the opposite opening sides of a number of adjacent links, on the other, an intermediate piece (6a...6d) with rolling contact action is inserted whit a coupling rib (14) for coupling the interme­ diate piece (6a...6d) to the link opening sides, and of which the oppposite-lying longitudinal side (10) forms the rolling surface cooperating with the longitudinal side of the pin, the end of each intermediate piece being provided with a recess (36, 38) at right angles to the longitudinal axis (30) running between the longitudinal sides (16a, 16b) through the coupling rib (14) and opening out into the end face (32, 34).

Description: Transmission chain with pivot pins and intermediate pieces with rolling contact action. The invention relates to a transmission chain as described in the preamble of Claim 1, and known from EP-A-0 275 608. For cheap manufacture of such a transmission chain (which is in particular intended for use in a continuously variable transmission) it is important to manufacture the many component parts as efficiently as possible, avoiding machine operations. The links can, of course, be manufactured by stamping out of sheet material, while the shaped pivot pins and intermediate pieces with rolling contact action can be made by a drawing a lengthwise section which is subsequently divided into discrete parts, following which the ends thereof are given the desired configuration by means of a machining operation. In the manufacture of intermediate pieces in particular problems occur because the coupling rib does not run over the entire length of the intermediate piece, but has to stop shortly before the two end faces in order to obtain supporting surfaces for the locking plates which are to be fitted at both ends of each pivot pin, and which can, for example, have a configuration such as shown in EP-A-0 275 608. This removal of a part of the coupling ridge by means of a machining operation on a part which is already small per se is an operation which is difficult to carry out, and which in practice often leads to a surface which is machined entirely smooth. Besides, a machining operation is in principle more expensive than a die-stamping operation. It is also conceivable for the ride to be partially planed off in a die-stamping tool, but this gives rise to problems with the die-stamping tool, in view of the fact that the chips released are difficult to remove. The object of the invention is to produce a configuration for the intermediate piece which not only makes it possible to manufacture the intermediate pieces without machining operation, but also improves the effect of locking plates of the type described above. This configuration is described in the characterizing part of Claim 1. Preferred embodiments of this configuration are the subjects of Claims 2 to 4, it being pointed out in particular with regard to Claim 3 that the diverging transitions described therein make the assembly of the transmission chain considerably easier. For this assembly, after the fitting of the links round the pivot pins, the intermediate pieces are inserted between pivot pins and links and the diverging transitions present in the preferred embodiment thereby serve as a "locating edge" by means of which the assembly is speeded up considerably. The process according to the invention which makes it possible to manufacture the intermediate pieces without machining operation is the subject of Claim 5 and results in a cheaper manufacture of the intermediate pieces. The invention is explained with reference to the drawing, in which: Figure 1 is an end view of a number of transmission chain links with their pivot pins and intermediate pieces designed according to the invention; Figure 2 is a side view of such an intermediate piece; Figure 3 is a perspective view of such an intermediate piece; Figure 4 is a perspective view of a pivot pin; Figure 5 is a perspective view of a link; Figure 6 is a perspective view of a locking plate used in such a transmission chain; Figure 7 is an end of a combination of a locking plate, pivot pin and intermediate pieces;; Figure 8 is a top view of a longitudinal section from which discrete intermediate pieces are formed by using the process according to the invention. The transmission chain according to the invention is of the type described in EP-A-0 060 008 and EP-A-0 102 673; such a transmission chain is in particular intended for use in a continuously variable transmission with cone pulleys. In such a transmission chain one link always cooperates with two pins; each side face of each pin always cooperates with a rolling contact face of an intermediate piece which is placed between the pin in question and an upright limitation of the opening present in the link; when they run between the cone pulleys the pins are clamped between them and carried along. In such a transmission chain the torque is transmitted by tension. Figure 1 shows in end view a part of three links 2a-2c with the pivot pins 4a-4b. The pin 4a cooperates with the links 2a, 2b, and the pin 4b with the links 2b, 2c. Each pin 4a, 4b cooperates with the appropriate links by means of two intermediate pieces for the pin 4a the intermediate pieces 6a, 6b, and for the pin 4b the intermediate pieces 6c, 6d. Each intermediate piece overlaps, as known per se, a number of links lying next to each other in the transverse direction of the chain. Each intermediate piece has a virtually flat longitudinal side 10 which forms the rolling surface with the pivot pin; the other longitudinal side 12 bears along part of its length a projecting rib 14. There are also two narrow longitudinal sides 16a, 16b. Each pivot pin has, viewed in cross-section, two end faces 18a, 18b, in Figure 1 shown for the pivot pin 4b and also shown in Figure 4; the end faces merge into the longitudinal faces 20a, 20b which roll over the intermediate pieces. Such a configuration is also known from the state of the art. In the two narrower longitudinal faces 19a, 19b a narrow groove is formed near the ends of pin, for the longitudinal face 19a indicated by the reference figures 22a, 22b, and for the longitudinal face 19b indicated by 22c in Figure 7. These grooves serve to take the end edges of the lips 24a, 24b of a locking plate 26 with a configuration which is shown in EP-A-0 275 608, filed in the name of Applicants and shown in Figure 6. The present invention relates in particular to the shaping of the ends of the intermediate pieces used in the transmission chain. As can be seen from Figures 2 and 3, in combination with the end view of the intermediate pieces according to Figure 1, a recess 36, 38 is formed in each intermediate piece, lying at right angles to the longitudinal axis 30 thereof, running between the two longitudinal sides 10 and 12 thereof, and opening out into the end face 32, 34. This recess in the embodiment shown is essentially semi-circular in longitudinal section, with a diameter equal to the width of the coupling ridge 14, and each recess merges via roundings 40a, 40b and 42a, 42b into the appropriate end face 32, 34. As Figure 2 shows, the configuration is symmetrical relative to the longitudinal axis 30. The figures also show how the end faces 32, 34 do not merge directly into the narrow longitudinal sides 16a, 16b, but via filets 44a, 44b and 46a, 46b, which is an advantage in the assembly of a transmission chain which is provided with the intermediate pieces according to the invention: the fillets 44a, 44b and 46a, 46b act as locating edges which facilitate the insertion of the intermediate pieces between the pivot pins and the links mating therewith. The configuration according to the invention has the advantage that the locking lips 48a, 48b disposed on the locking plate 26, which in a locking plate with a configuration described in the above-mentioned document EP-A-0 275 608 can extend only to the longitudinal side of the intermediate piece, can now extend much further, as can be seen clearly from Figure 7. This achieves a more secure locking of the intermediate pieces and the links between the two locking plates disposed on a pivot pin. An important aspect of the invention is the way in which the intermediate pieces are manufactured. This manufacture takes place according to the invention by cold drawing of a longitudinal section with a cross-section configuration corresponding to the intermediate pieces finally to be obtained an by trimming this section to the desired length by means of a cross-shaped die-stamping tool whose external contours correspond to those of two recesses and end face configurations lying opposite each other. Figure 8 shows a longitudinal section 50 in side view and an end view of the cross-shaped trimming tool 52 which is used for trimming the section 50. The external contours 54a, 54b correspond to the contour of the left and right end faces respectively of the intermediate piece in Figure 2, and the trimming movement takes place at right angles to the plane of the drawing. The end faces with recesses of two intermediate pieces are thus always formed in a single operation. The machining operation necessary for the known intermediate pieces is dispensed with, with all the advantages this entails.

Claims: Transmission chain to be used for a cone pulley drive, comprising a number of intercoupled links (2a...2c) each accommodating two pivot pins (4a, 4b) which lie at right angles to the link plane and are inserted through link openings in which the end surfaces (18a, 18b) of these pivot pins (4a, 4b) cooperate as friction surfaces with the surfaces of the cones of the pulley drive, the longitudinal sides (20a, 20b) of said pivot pins (4a, 4b) form rolling surfaces with a radius of curvature different from the radius of curvature of an intermediate piece (6a...6d) cooperating therewith, said intermediate piece (6a...6d) being provided between each pivot pin (4a, 4b) and the opposite-lying upright opening sides of a number of adjacent links for rolling contact with said pin (4a, 4b) while a first longitudinal side (12) of said intermediate piece (6a...6d) bears a coupling rib (14) running in its lengthwise direction for coupling the intermediate piece (6a...6d) to the link opening sides and the opposite-lying second longitudinal side of said intermediate pin (6a...6d) forms a rolling surface (10) being in rolling contact with the longitudinal side of the pivot pin (4a, 4b), the longitudinal sides (10,12) being connected to each other by two opposite-lying narrow longitudinal sides (16a, 16b), characterised in that a recess (36, 38) is formed on each end of the intermediate piece (6a...6d), said recess (36, 38) lying at a right angle with the longitudinal axis (30) of the intermediate piece (6a...6d), running between the narrow longitudinal sides (16a, 16b) of the intermediate piece (6a...6d) through the coupling rib (14) and opening out into the end face (32, 34) of the intermediate piece (6a...6d). Transmission chain according to Claim 1, characterized in that the recess (36, 38) is approximately semi-circular with a diameter equal to the width of the coupling rib (14) and merging via roundings (40a, 40b, 42a, 42b) into the end face (32, 34) which is arched in longitudinal section. Transmission chain according to Claim 1 or 2, characterized in that each end face (32, 34) merges via diverging transitions (44a, 44b, 46a, 46b) into the narrow longitudinal sides (16a, 16b). Transmission chain according to Claims 1-3, characterized in that coupling rib (14), recess (36, 38) and transitions are in longitudinal section symmetrical relative to the longitudinal axis (30) of the intermediate piece. Process to manufacture an intermediate piece (6a...6d) used in a transmission chain as defined in the preceding claims, characterised in that in a continuous drawing operation a section is made with its cross-section corresponding to that of said intermediate piece (6a..6d), and this section is divided into discrete rotting intermediate pieces with an end configuration as defined in the preceding claims by trimming with a cross-shaped die stamping toot with an edge configuration (54a,54b) corresponding to the externat contours (36,38) of the end faces of said intermediate piece (6a...6d) thus forming said recess (36).

Inventors: HOLWEG, HERMANUS ANTONIUS CANISIUS
Applicants: VOLVO CAR SINT-TRUIDEN, NAAMLOZE VENNOOTSCHAP
Application year: 1989
Main classification: F16H9
IPC codes: F16G5, F16H9