Timing chain with timing marks and method of manufacturing the same

Abstract: [PROBLEM] To provide a timing mark on a place at a specific part of a timing chain in a state in which the quality of the timing chain is maintained. [SOLVING MEANS] A timing chain 4 is endless in which an outer plate 1 and an inner plate 2 are connected by means of connecting pins 3. In the timing chain 4, the outer plate 1 at a specific part on one side has a timing mark 1'. The timing mark 1' is in the shape of a web extending from an inner edge to an outer edge between the connecting pins of the outer plate 1. The timing mark 1' is provided by a baking coating after the timing chain has been composed.

Description: [INDUSTRIAL FIELD] The present invention relates to a timing chain wound between members which require a synchronous rotation. The timing chain manufactured according to the present invention is wound, for example, between a crank sprocket and a cam sprocket of an engine for a vehicle, and is used for the synchronous rotation of a crank shaft with a cam shaft. Further, the timing chain of the present invention is provided to be wound between a crank sprocket and a balancer sprocket of an engine for a vehicle, and is used for the synchronous rotation of a crank shaft with a balancer shaft. [PRIOR ART] The timing chain is used for the synchronous rotation as mentioned above. Therefore, a sprocket having timing marks and a timing chain having timing marks are used. The timing marks are registered and the timing chain is wound about the sprocket for achieving the synchronous rotation. Incidentally, generally, the timing marks of the timing chain are provided by a method of marking some marks on a single plate prior to composition of the timing chain. There is a further method of applying some marks to the timing chain by a plating treatment to provide timing marks. In this method, however, gases generated during the plating treatment, for example, hydrogen should be removed, and addition of a baking treatment is necessary to prevent the lowering of fatigue strength, the process management should naturally be severe, and the production efficiency is extremely bad. The applicant has previously proposed a timing chain applied with timing marks by a color baking coating as disclosed in Japanese Patent Laid-Open No. 242829/1997. In this timing chain, timing marks obtained by the color baking coating are applied to outer plates of a part composing the timing chain, which is composed endlessly together with other plates. However, the outer plates having timing marks are prepared via the manufacturing process separately from other outer plates. Therefore, it is necessary to store, as stocks, outer plates having timing marks and outer plates having no timing marks every type of the timing chain. This poses a problem in that many numbers of steps for managing parts constituting the timing chain are necessary, and the securing of storage areas for parts is very wasteful. Further, since coated outer plates are assembled with other plates, the coated outer plates have to be incorporated into the specific parts in the midst of composition of the timing chain. Normally, the specific parts are positioned on one side of the timing chain though different according to the type of the timing chain, and are positioned at two places in the chain. Accordingly, when the timing chain is composed, it is necessary to specify the surface and back of the timing chain, to specify the predetermined position in the chain, and then to assemble the coated outer plates. Further, since the coated outer plates have to be switched to the other outer plates to compose the timing chain, a number of steps has been required to assemble the timing chain. Furthermore, since after the whole surface of the outer plates have been coated, the timing chain is composed, when the outer plates are pressed into the pins when the timing chain is assembled, the coating is sometimes peeled off. When the coating is partly peeled off, the external appearance of the timing chain becomes worsened. When the coating is completely peeled off, the timing marks cannot be discriminated, failing to assemble them between the members for which the synchronous rotation is required. To solve the aforementioned problem, it has been known, see DE-A-4339321, to manufacture a timing chain as defined by the preamble of claim 1. When the timing chain thus manufactured is wound between the members, the members can be rotated synchronously. The method of manufacturing the timing chain according to the present invention is specified with regard to DE-A-4339321 by the characterising features of claim 1. The timing mark is provided by the color baking coating of coating other than metal color of the plate material, the spray coating of the coating, the stamp of the coating, or the laser, etc. This timing mark is provided not completely but partly. This prevents an entry of a coating between the plate and the connecting pin. [EMBODIMENTS] Fig. 1 shows a first embodiment of a timing chain according to the present invention. In the present embodiment, there is shown a timing chain 4 of a roller type which is endless in which an outer plate 1 and an inner plate 2 are connected by means of connecting pins 3. This timing chain 4 is wound between a crank sprocket 7 mounted on a crank shaft 5 and a cam sprocket 8 mounted on a cam shaft 6 in the vehicle engine. The timing chain 4 is sometimes wound between a crank shaft and a member for which synchronous rotation is required like a balancer shaft. In the timing chain 4 according to the present embodiment, a timing mark 1' is provided on the outer plate 1 at a specific part on one side. This specific part is a part corresponding to a timing mark 9 of the crank sprocket 7 and a timing mark 10 of the cam sprocket 8. The timing mark 1' corresponding to the timing mark 9 is provided on one outer plate 1, and the timing marks 1' corresponding to the timing mark 10 are provided on a plurality of outer plates 1, 1. The timing mark 1' is composed endlessly, after which it is provided on the timing chain. The respective timing marks 1' are in the shape of a web extending from an inner edge to an outer edge between the connecting pins of the outer plate 1. Thereby, even in the case where the timing mark 1' is provided by coating, the coating is prevented from being moved in and between the outer plate 1 and the connecting pin. The timing mark 1' is protected by the connecting pin projecting from the surface of the outer plate 1. In the present invention, the form of the timing mark 1' can be freely selected without increasing the number of assembling steps of the timing chain 4. That is, the form of the timing mark 1' corresponding to the timing mark 9 is made different from that of the timing mark 1' corresponding to the timing mark 10, and the timing mark 1' can be provided on one outer plate 1. For example, the timing mark 1' corresponding to the timing mark 9 is formed to be web-like and the timing mark 1' corresponding to the timing mark 10 is formed to be circular whereby one timing mark 1' can be made to correspond to the crank sprocket 7, and the other timing mark 1' can be made to correspond to the cam sprocket 8. The timing mark 1' is colored by the baking coating. A preferable color is a color other than a metal color and a dark color which are colors peculiar to materials used for parts of the vehicle engine. More specifically, preferred colors are colors having a high brightness and coloration such as white, yellow, pale blue, pink, green-yellow, red or the like. The timing marks may be provided by the spray coating of coating, the stamp of coating or laser. Fig. 2 shows a second embodiment of a timing chain 20 with a circular timing mark 22 provided on a pitch line between connecting pins, in the surface of an outer plate 21. Fig. 3 shows a second embodiment of the timing chain according to the present invention. A timing chain 30 in the present embodiment is a silent chain. There is provided a web-like timing mark 32 extending from an inner edge to an outer edge of a guide plate 31 between connecting pins, in the surface of a guide plate 31. Fig. 4 shows a timing chain 40 with a circular timing mark 42 provided on a pitch line between connecting pins, in the surface of a guide plate 41. [EFFECT OF THE INVENTION] In the present invention, since the timing marks are provided on the outer plates of the timing chain after being composed, the number of the outer plates constituting the timing chain can be reduced in half, whereby the number of parts in stock are reduced, and the number of steps of managing parts can be considerably reduced. Further, when the timing chain is manufactured, it is also unnecessary that the outer plate having the timing mark is switched to the outer plate having no timing mark for assembly. According to the kind of timing chains and synchronous members between which the timing chain is wound, the color and mounting means of the timing marks can be suitably selected, and the number of timing marks required and the position of the timing marks to be provided can be suitably selected whereby a freedom of design of the timing chain having the timing marks is enhanced. [BRIEF DESCRIPTION OF THE DRAWINGS] [FIG. 1] A side view showing a first embodiment of a timing chain according to the present invention. [FIG. 2] A side view showing a timing chain not according to the present invention. [FIG. 3] A side view showing a second embodiment of a timing chain according to the present invention. [FIG. 4] A side view showing a timing chain not according to the present invention. [DESCRIPTION OF REFERENCE NUMERALS] 4, 20, 30, 40 Timing chain 1, 21, 31, 41 Plate 1', 22, 32, 42 Timing mark

Claims: A method of manufacturing a timing chain (4; 30) having timing marks (1'; 32), comprising the steps of: assembling a plurality of links defined by inner plates (2) and outer plates (1; 31) interconnected by connecting pins (3) into an endless chain (4; 30); and thereafter imposing a timing mark (1'; 32) at a predetermined location on at least one outer plate (1; 31) characterized in that the timing mark imposing step includes the step of a color baking coating on said outer plate and that the timing mark (1'; 32) is in the shape of a web extending from an inner edge to an outer edge between the connecting pins (3) of the outer plate (1; 31). The method according to claim 1, wherein the colored timing mark (1'; 32) has a color such as white, yellow, pale blue, pink, green-yellow or red.

Inventors: KAGA ARIMASA, SHIMAYA KAZUHIKO, KAGA, ARIMASA, SHIMAYA, KAZUHIKO
Applicants: TSUBAKIMOTO CHAIN CO, TSUBAKIMOTO CHAIN CO.
Application year: 1998
Main classification: F16G13
IPC codes: F16G13