JP2950732B2 - Cam gear drive gear bearing structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cam gear drive gear bearing structure suitable for a motorcycle, especially a racer.

[0002]

2. Description of the Related Art Conventionally, for example, as shown in FIG. 4, an engine body 100 (cylinder head, cylinder, case, etc.)
And a cover 101 (made of cast material) separate therefrom, the cam gear drive gear 102, the holder plate 103,
Since the driving devices such as 03a, the bearing 104 and the pin 105 are sandwiched and supported separately, it is difficult to secure the rigidity of the bearing portion. In addition, large parts such as the cover 101 are required, and additional processing with the parts on the engine body 100 side is required to secure the flatness of the upper and lower packing surfaces 106 and 107. That is, there remain problems such as an increase in the number of parts, an increase in the number of processing steps, and a decrease in the rigidity of the bearing portion. Conventionally, Japanese Patent Publication No. 62-393
No. 02 has a cam gear drive gear meshing with the intake / discharge cam gear, and a crank gear driven gear meshing with the crank gear in an engaged state, and each of the gears is press-fitted into opposed holes of two holder plates. The structure in which the supported gear cassette is arranged between the cylinders is shown. However, in that case, there is also a relationship of the arrangement location, fixing the angle material legs to the upper outer surface of both holder plates,
Adjust the backlash with the intake and exhaust cam gear by bolting the leg piece to the cylinder head via a shim, fix the leg piece bent at 90 degrees at the lower end of the holder plate, and fasten it to the cylinder with bolts, etc. And it takes time to adjust the backlash.

[0003]

An object of the present invention is to reduce the number of parts, reduce the number of processing steps, and improve the rigidity of a bearing.

[0004]

According to a first aspect of the present invention, there is provided a cam gear drive gear meshing with a suction / discharge cam gear, and a crank gear driven gear meshing with a crank gear in an engaged state. The above-mentioned gears are supported by press-fitted collars, the small-diameter part of the stepped shaft is fitted to the collar of the cam gear drive gear, and the tip of the small-diameter part is fitted to the bearing hole in the inner wall of the cylinder head. The large diameter part concentric with the small diameter part fits into the bearing hole in the outer wall of the cylinder head, and the collar is held between the small diameter part and the large diameter part by the step between the small diameter part and the inner wall surface of the cylinder head to adjust the position of the collar. It is a bearing structure of a cam gear drive gear, characterized in that it is determined.

According to a second aspect of the present invention, the length of the large diameter portion is increased to a value close to the length of the collar, and the large diameter portion is inserted into a bearing hole in a cylindrical boss provided on the outer wall of the cylinder head. 2. The cam gear drive gear bearing structure according to claim 1, wherein the shaft is fitted with a circlip at an end on the side opposite the collar in the bearing hole, and sealed with an O-ring.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference numeral 1 in FIG. 1 denotes a gear cassette. Pipe-shaped collars 3, 4, and 5 are press-fitted into holes drilled at opposing positions of two holder plates 2 and 2a so that both ends thereof slightly project. A cam gear drive gear 7 is mounted on the collar 3 between the holder plates via a ball bearing 6 on the collar 3 between the holder plates. The cam gear drive gear 7 is an equidistant intake cam gear 8 and an exhaust cam gear 9 (collectively referred to as intake and exhaust cam gears). The gears are engaged with optimal backlash by the bearing structure described later. A washer 10 whose outer diameter is equal to that of the inner race is clamped between the inner race of the ball bearing 6 and the holder plates 2 and 2a on both sides. An intermediate gear 12 is supported on the collar 4 via a ball bearing 6, and the intermediate gear 12 meshes with the cam gear drive gear 7 with an optimal backlash. This is obtained with the accuracy of the positions of the collars 3, 4 on the holder plates 2, 2a and of the two gears 7, 12. The collar 5 has a crank gear and a driven gear 13 via a ball bearing 6.
, And the crank gear driven gear 13 meshes with the intermediate gear 12 with the optimal backlash for the same reason. The driven gear 13 of the crank gear is meshed with the crank gear 14 with an optimum backlash by a driving mechanism described later. Holder plate 2, 2a
The upper cam gear driving gear 7 meshes with the intermediate gear 12, the intermediate gear 12 and the crank gear driven gear 1
Viewing windows 15 and 16 are also provided at the meshing portion 3 to reduce the weight, so that the backlash can be measured. The four corners at the center of the holder plates 2 and 2a in FIG.
7 are held at predetermined intervals. That is, a U-shaped spacer gauge (not shown) between the holder plates 2 and 2a.
The holder plates 2 and 2a are integrated by crimping both ends of the rivet 17 between the holder plates 2. Thus, the gear cassette 1 can handle the gears 7, 12, and 13 as one unit while maintaining the gears in an optimum meshing state.

The upper end of the gear cassette 1 enters the space between the inner wall 19a of the cylinder head 19 and the outer wall 19b integral therewith, and the small diameter portion 2 of the horizontal stepped shaft 20
1 fits snugly into the collar 3 and the tip fits snugly into the bearing hole 22 in the inner wall 19a, and the large diameter portion 23 concentric with the small diameter portion 21 is provided in the cylindrical boss 18 of the outer wall 19b. The bearing hole 24 fits snugly. Both end surfaces of the collar 3 have a step 25 between the small diameter portion 21 and the large diameter portion 23 and the inner wall surface 2.
6 pinched. The length of the large-diameter portion 23 is increased to a value close to the length of the collar 3 so that the outer wall 1 of the cylinder head 19 is
The large-diameter portion 23 is fitted to the inside of the bearing hole 24 in the cylindrical boss portion 18 provided at 9b almost completely. Therefore, the length of the bearing hole 24 is also long so as to be close to the length of the collar 3. Then, the collar 3 is stopped by the circlip 27 at the end on the side opposite the collar 3 in the bearing hole 24 and sealed by the O-ring 28, and the collar 3 is clamped by the step 25 of the stepped shaft 20 and the inner wall surface 26 of the inner wall 19a. doing. Reference numeral 29 denotes a screw hole into which a pull-out bolt (not shown) of a jig is screwed when the stepped shaft 20 is pulled out. The bearing hole 24, the bearing hole 22, and the inner wall surface 26 can be formed concentrically by processing from one side (the outer wall 19 b side) of the cylinder head 19.
Intake and discharge cam gear 8 on camshaft 30 supported by
The backlash between the gear 9 and the cam gear drive gear 7 can be optimally maintained from the beginning.

A female screw 32 is provided on the inner surface of the collar 4, and a bolt 36 is screwed into the female screw 32 through a fool hole 35 of a cylindrical boss 34 of a cylinder 33, and the position of the collar 4 is adjusted by the cylinder 33. It has established. The fool hole 35 needs to be large enough to rotate the gear cassette 1 about the stepped shaft 20 and adjust the backlash between the crank gear 14 and the crank gear driven gear 13. It may be a long hole having an arc-shaped cross section centered on the stepped shaft 20.

The collar 5 is screwed to a crankcase 41 by bolts 40 through washers 38 and 39. 43
Female screw. The gap 42 is formed by making the inner diameter of the collar 5 larger than the screw diameter of the mounting bolt 40. This gap also acts as a relief during backlash adjustment.

[0010] In FIG 2, the crank gear 14: vertical line 45 passing through the center O ₂ of the color 3 than the vertical line 44 passing through the center O ₁ of the (rotational direction arrow R) are shifted to the right by L ₁ Moreover, a straight line 46 connecting the center O ₂ , the center O ₃ of the collar ₄ and the center O _{4 of the} collar 5 is inclined downward to the right by an angle α with respect to the vertical line 45. Therefore, the crank gear driven gear 13 is a crank gear 14 that rotates in the direction of arrow R.
It meshes with the upper right part of the crank gear 14 so as to receive the thrust in the direction further away. Reference numeral 57 denotes a cylindrical boss provided on the cylinder 23. The tip (the left end in FIG. 2) of the adjusting bolt 48 screwed into the female thread of the boss 57 contacts the edge of the holder plate 2. 49 is a double nut.

To mount the gear cassette 1, the small diameter portion 21 of the stepped shaft 20 is inserted into the collar 3 (FIG. 1), the position is fixed by the circlip 27, and the bolts 36 and 40 are half-tightened. Loosen the nut 49 in FIG.
Then, the backlash between the crank gear 14 and the crank gear driven gear 13 is adjusted with a thickness gauge, and then the nut 49 and the bolts 36 and 40 are tightened.

[0012]

According to the first aspect of the present invention, the collar 3 is connected to the bearing hole 22 of the inner wall 19a of the cylinder head 19 and the outer wall 1 of the cylinder head 19.
Stepped shaft 20 supported by concentric bearing hole 24 of 9b
, The intake cam gear 8 and the exhaust cam gear 9, which are also supported by the cylinder head 19.
Can always be kept in a good state. The bearing holes 24, the bearing holes 22, and the inner wall surface 26 can be easily and accurately processed from one side of the outer wall 19b, and the stepped shaft 20 can be processed with high precision. . Also, the structure for supporting the collar 3 has been simplified,
The number of parts also decreases.

According to the second aspect of the present invention, since the large-diameter portion 23 and the boss portion 18 are lengthened, the length of engagement with the bearing hole 24 is increased, the holding rigidity of the outer wall 19b is increased, and durability is improved from this aspect. Can be improved. Since the circlip 27 is used, the fixing structure of the stepped shaft 20 is simplified, and attachment and detachment are also facilitated. Since the O-ring 28 is mounted, oil leakage can be prevented.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view.

FIG. 2 is a schematic sectional view taken along the line II-II of FIG.

FIG. 3 is a sectional view taken along the line III-III in FIG. 2;

FIG. 4 is a longitudinal sectional view showing an example of a conventional structure.

[Explanation of symbols]

 2, 2a Holder plate 3, 4, 5 Collar 7 Cam gear drive gear 8 Intake cam gear 9 Exhaust cam gear 13 Crank gear driven gear 19 Cylinder head 19b Outer wall 20 Stepped shaft 21 Small diameter portion 22 Bearing hole 23 Large diameter portion 24 Bearing hole 25 Step 26 Inner wall surface 27 Circle clip 28 O-ring

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁶ , DB name) F16H 57/00-57/04 F01L 1/02

Claims (2)

(57) [Claims] 1. A cam gear driving gear meshing with a suction / discharge cam gear, and a crank gear driven gear meshing with a crank gear in an meshing state, and each of the gears is a collar press-fit into opposed holes of two holder plates. The small diameter part of the stepped shaft is fitted to the collar of the cam gear drive gear, the tip of the small diameter part is fitted to the bearing hole in the inner wall of the cylinder head, and the large diameter is concentric with the small diameter part of the stepped shaft. The diameter portion is fitted into a bearing hole in the outer wall of the cylinder head, and the collar is sandwiched between the step portion between the small diameter portion and the large diameter portion and the inner wall surface of the cylinder head to determine the position of the collar. Cam gear drive gear bearing structure. 2. The method according to claim 1, wherein the length of the large diameter portion is increased to a value close to the length of the collar, and the large diameter portion is fitted into a bearing hole in a cylindrical boss provided on an outer wall of a cylinder head. 2. The bearing structure for a cam gear drive gear according to claim 1, wherein the circlip at an end on the side opposite to the collar in the bearing hole prevents the removal and seals the O-ring.