JP3525305B2 - Sprocket mounting structure - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sprocket mounting structure. 2. Description of the Related Art Conventionally, in an engine as shown in FIG. 4, a crank sprocket 3 is fixed to a crankshaft 2 on a cylinder block 1 side, and a primary side of the crank sprocket 3 is attached to the crank sprocket 3. A chain 4 is mounted, and an upper portion of the primary side chain 4 is mounted on an idler sprocket 7 rotatably fitted to an idler sprocket shaft 6 fixed to a cylinder head. Are guided by primary side chain guides 8 and 8, and tension is applied by a primary side tensioner 9. A secondary chain 10 is mounted on the idler sprocket 7, and the secondary chain 10 is further mounted on the cam sprockets 11. The idler sprocket 7 and the idler sprocket shaft 6 are fixed to the shaft mounting surface 5a of the cylinder head with a mounting structure as shown in the sectional view of FIG. The idler sprocket 7 fitted to the outside as possible has primary teeth 7b on which the primary chain 4 is mounted and secondary teeth 7c on which the secondary chain 10 is mounted, both ends of the cylindrical portion 7a. Formed in the part,
The cylindrical portion 7a of the idler sprocket 7 is fitted around the outer periphery of the idler sprocket shaft 6, and the primary chain 4 is hung on the primary tooth portion 7b, and the outer end is inserted into the dowel hole 5c of the shaft mounting surface 5a. The engagement hole 6b formed in the flange portion 6a of the idler sprocket shaft 6 is positioned with respect to the dowel pin 12 which is fitted and projected, and the idler sprocket shaft 6 is held on the shaft mounting surface 5a. A bolt 14 is inserted through the plate 13 from the outside along the center axis of the shaft 6, and the tip of the bolt 14 is tightened into a screw hole 5 b formed in the shaft mounting surface 5 a. The idler sprocket shaft 6 is attached to the surface 5a. Just installed an idler sprocket 7 is set. In such a conventional mounting structure, when the idler sprocket shaft 6 is mounted on the mounting surface 5a, the idler sprocket shaft 6 is held with a considerable force against the tension of the primary side chain 4.
The work of aligning the engagement hole 6b of the idler sprocket shaft 6 with the dowel pin 12 is required, and the engagement with the dowel pin 12 is extremely troublesome.
There is a problem that the mounting operation is extremely difficult. Further, in the conventional structure, it is necessary to form the engaging hole 6b in the idler sprocket shaft 6, and the dowel hole 5c and the dowel pin 12 are formed on the shaft mounting surface 5a side. It has to be provided, and there is a problem that the structure becomes complicated and the processing cost increases. SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and does not provide a sprocket mounting structure having a simple structure and facilitating the mounting operation. The gist of the invention is to attach a sprocket to a screw hole formed in a mounting surface by tightening a bolt inserted through a center axis of a sprocket shaft on which a sprocket is rotatably fitted, so that the sprocket shaft is fixed to the mounting surface. In the structure, an end of the sprocket shaft is provided with the sprocket.
The sprocket shaft is formed on the outer periphery of the screw hole on the mounting surface while forming a concave portion having an enlarged inner diameter of the shaft.
A projection for holding the sprocket shaft, which can be fitted into the recess at the end of the shaft, is formed . An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of the mounting structure of the first embodiment, in which an idler sprocket 7 protrudes outward from both ends of a cylindrical tubular portion 7a and is integrally formed with a primary side tooth portion 7b and a secondary side tooth portion. 7c, the primary side tooth portion 7b is formed to have a large diameter to mount the primary side chain 4 with the crank sprocket 3, and the inner diameter of the cylindrical portion 7a of the idler sprocket 7 is formed. The idler sprocket shaft 6 having an outer diameter corresponding to the above has a body portion 6d which can rotate the cylinder portion 7a while being inserted into the cylinder portion 7a. The flange 6a is integrally formed in a flange shape so as to protrude outward, and an engagement recess 6c having an enlarged inner diameter is formed on the inner peripheral side of the flange 6a. A bolt hole 6e through which a bolt can be inserted is formed on the idler sprocket shaft 6 on the side opposite to the engagement recess 6c. An oil groove 6f for introducing oil toward the idler sprocket is formed in the body 6d. On the other hand, in this embodiment, a shaft holding projection 5d is formed on the outer periphery of the screw hole 5b formed in the mounting surface 5a so as to protrude outward (to the left in the drawing).
The shaft holding projection 5d is formed to have an outer diameter that engages with an engagement recess 6c formed in the idler sprocket shaft 6. The procedure for mounting the idler sprocket 7 on the shaft mounting surface 5a is as follows. The primary chain 4 is mounted on the primary teeth 7b of the idler sprocket 7, and the idler sprocket is placed in the cylinder 7a of the idler sprocket. The shaft 6 is inserted, and in this state, the engaging recess 6c of the idler sprocket shaft 6 is fitted into the shaft holding projection 5d formed on the shaft mounting surface 5a, and the idler sprocket is inserted into the shaft holding projection 5d. The shaft 6 can be temporarily held, and even when the tension of the primary side chain 4 is acting, the idler sprocket shaft 6 can be favorably held on the shaft mounting surface 5a against the tension, In this state, it is formed along the central axis of the idler sprocket shaft 6. It is inserted a bolt 14 from the left side into the bolt hole 6e that is, the tightening screwed tip of the bolt 14 into the screw hole 5b. At this time, bolt 14
A disk-shaped plate 13 is interposed on the head of the idler sprocket 7, and the plate 13 presses the idler sprocket 7 toward the flange portion 6a of the idler sprocket shaft 6 to prevent the idler sprocket 7 from being pulled out. The idler sprocket 7 can be attached by tightening the bolt 14 to firmly fix the idler sprocket shaft 6. In this embodiment, the engaging recess 6c is easily fitted into the shaft holding projection 5d by pressing the idler sprocket shaft 6 toward the screw hole 5b formed in the shaft mounting surface 5a. The sprocket shaft 6 can be held, and the difficult work of aligning the small engagement hole with the dowel pin as in the related art can be omitted, and the idler sprocket shaft 6 can be held extremely easily. FIG. 2 shows a mounting structure according to a second embodiment. In this embodiment, a concave portion 5e for holding a shaft is formed in the outer periphery of the screw hole 5b of the shaft mounting surface 5a. On the flange portion 6a side of the idler sprocket shaft 6, an engagement projection 6g is further formed to protrude rightward in the drawing from the flange portion 6a, and the engagement projection 6g is used for holding the shaft. It is formed to have an outer diameter that can be fitted into the recess 5e. The other construction is the same as that of the first embodiment. In this embodiment, the idler sprocket shaft 6 is inserted into the cylindrical portion 7a of the idler sprocket 7 with the primary side chain 4 mounted thereon. In this state, the idler sprocket shaft 6 is pressed toward the screw hole 5b to fit the engaging projection 6g at the tip of the idler sprocket shaft 6 into the shaft holding recess 5e, whereby the idler sprocket shaft is temporarily attached to the shaft mounting surface 5a. The sprocket shaft 6 can be held, and the primary side chain 4
The idler sprocket shaft 6 can be satisfactorily held against the tension of the bolt, and in this state, the bolt 14 is inserted through the idler sprocket shaft 6 with the plate 13 interposed therebetween, and the bolt 14 is screwed into the screw hole 5b. The idler sprocket shaft 6 can be firmly fixed to the mounting surface 5a by tightening the bolts 14 together, thereby facilitating the mounting operation. According to the present invention, a bolt inserted through a center shaft of a sprocket shaft on which a sprocket is rotatably fitted is fastened to a screw hole formed on a mounting surface, and the sprocket shaft is mounted on the mounting surface. In the fixed mounting structure,
At the end of the sprocket shaft, the sprocket
The sprocket shaft is formed on the outer periphery of the screw hole on the mounting surface while forming a concave portion having an enlarged inner diameter of the shaft.
The convex portions of the sprocket shaft holding that can be fitted to the recess of bets ends are formed, is formed a recess <br/> end of the sprocket shaft to the mounting surface side in a state of being fitted sprocket The sprocket shaft can be temporarily held in good condition on the mounting surface by fitting the sprocket shaft into the convex part, and the sprocket shaft can be held well against the tension of the chain mounted on the sprocket. The sprocket shaft can be firmly fixed to the mounting surface by inserting the bolt into the screw hole of the mounting surface and the positioning of the sprocket shaft to the small dowel pin as in the past is unnecessary, and the sprocket mounting work Can be performed very easily, and workability is improved. Further, since the structure can be simplified as compared with the related art, the processing cost can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional configuration view of a mounting structure according to a first embodiment. FIG. 2 is a cross-sectional configuration diagram of a mounting structure according to a second embodiment. FIG. 3 is a sectional configuration diagram of a conventional mounting structure. FIG. 4 is a configuration diagram showing an arrangement state of a sprocket and a chain. [Description of Signs] 4 Primary side chain 5a Shaft mounting surface 5b Screw hole 5d Shaft holding protrusion 5e Shaft holding recess 6 Idler sprocket shaft 6a Flange 6c Engagement recess 6g Engagement protrusion 7 Idler sprocket 7b Primary teeth Part 7c Secondary side tooth part 13 Plate 14 Bolt

Continuation of the front page (56) References JP-A 2-141603 (JP, U) JP-A 55-74852 (JP, U) JP-A 62-30057 (JP, U) (58) Fields surveyed (Int .Cl. ⁷ , DB name) F16H 51/00-55/30

Claims (1)

(57) [Claim 1] A bolt inserted through the center shaft of a sprocket shaft on which a sprocket is rotatably fitted is fastened to a screw hole formed on a mounting surface, and the sprocket is mounted on the mounting surface. in the mounting structure for fixedly shaft, said Supuro
At the end of the ket shaft, the sprocket shaft
A concave portion having an enlarged inner diameter is formed, while a concave portion at the end of the sprocket shaft is formed on the outer periphery of the screw hole on the mounting surface.
Projections of sprocket shaft holding capable fit the parts
A sprocket mounting structure, characterized in that a sprocket is formed .