JPH039281B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of assembling a timing gear for driving a camshaft of a twin cam valve system in a DOHC engine.

(Prior Art) In a DOHC engine, the crankshaft and both the intake side and exhaust side camshafts are generally connected by a rotation transmission means using a pulley and a belt or sprocket chain. Although it is designed to rotate both camshafts,
Recently, a system has been developed in which a crankshaft and one of two camshafts are connected by the above-mentioned rotation transmission means, and the camshaft and the other camshaft are connected by gear meshing. . According to this method,
This has the advantage that the space required to assemble the valve system including both camshafts and gears is reduced.

(Problems to be Solved by the Invention) Incidentally, both the intake side and exhaust side camshafts must operate at predetermined timings, so timing must be aligned when assembling their drive gears.

In this case, a general method is to mark each gear on the intake side and the exhaust side, and match the marks so that the two gears mesh to match the timing.

In other words, when matching Mark comrades,
First, one of the intake and exhaust gears, for example, the intake gear, is fixed in position on its shaft, and then the other exhaust side gear is placed in front of the shaft and marked on the intake gear. Bite together so that they fit together,
Thereafter, the exhaust side gear is rotated and moved along the teeth of the intake side gear, and the exhaust side gear is positioned on its shaft to facilitate assembly.

However, when using this method, in order to ensure reliability of assembly accuracy, it is necessary to rotate both gears together with the camshaft and check the marks by aligning them again, which inevitably increases the number of man-hours and is necessary for mass production lines. It is difficult to say that this method is sufficient for use in

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the need for rotating both gears after they are assembled, thereby ensuring reliability in assembly accuracy without increasing the number of man-hours.

(Means for Solving the Problems) Therefore, the present invention provides that the intake side gear and the exhaust side gear, which are marked at two points, the first point and the second point, are first connected to their shafts. Then, the other gear is meshed with the one gear by aligning their first point marks, and then the other gear is rotated and moved along the teeth of the one gear. When the other gear is positioned on its shaft portion, the marks at the second points of both gears are brought into contact with each other.

(Function of the Invention) According to the present invention, alignment can be checked using the mark at the second point that is brought into contact when the assembly of both gears is completed, so there is no need to rotate both gears again.

(Example) Examples of the present invention will be described below with reference to the drawings.

First, in FIG. 2, 1 is an engine, 2 is its oil pan, 3 is a cylinder block, 4 is a cylinder head, 5 is a crankshaft, 6 is an intake camshaft, and 7 is an exhaust camshaft. A timing pulley 8 is fixed to the crankshaft 5, and a timing pulley 9 and a timing gear 10 are fixed to the intake side camshaft 6.
A timing gear 11 is fixed to the exhaust side camshaft 7. A timing belt 12 is stretched between the timing pulley 8 and the timing pulley 9, and the rotation of the crankshaft 5 is transmitted to the intake camshaft 5 via the timing belt 12. 13 is an idler pulley that applies tension to the timing belt 12. The timing gear 11 and the timing gear 10 are directly meshed with each other, and the rotation of the crankshaft 5 is transmitted to the exhaust side camshaft 7 via these timing gears 10 and 11. In addition, 14
is the crank key.

As shown in an enlarged view in FIG.
17 and 18 are fixing caps. The centers of the bearings 15 and 16 become the shafts of the respective timing gears 10 and 11.

Marks 19 to 22 are attached to the timing gears 10 and 11 at two locations, respectively. Here, the locations with marks 19 and 20 are the first points, and the locations with marks 21 and 22 are the first points. is the second point. Here, marks 19, 20
The marks 21 and 22 have two points, and the marks 21 and 22 have one point, and the first point and the second point have different design properties.
There are various ways to make the design different, such as color and shape.

When assembling the valve drive system having such a configuration into the engine 1, first, the timing pulleys 8 and 9 and the timing gears 10 and 11 are fixed to the crankshaft 5 and the camshafts 6 and 7, respectively.

First, the intake camshaft 6 is assembled into the bearing 15, the cap 17 is closed and fixed, and the timing of the camshaft 6 and the crankshaft 5 is aligned. In this case, for example, with the crank key 14 facing upward, the timing gear 1
It is sufficient to hang the belt 12 with the 0 mark 21 placed on the horizontal line. Note that marks 23 and 24 are provided instead of marks 19 and 20, and these marks 23,
It is easier to carry out the work by holding the crank key 24 and the crank key 14 upward.

Next, the timing gear 11 of the exhaust side camshaft 7 is meshed with the timing gear 10 of the intake side camshaft 6 so that their first point marks 19 and 20 are aligned (as indicated by the two-dot chain line). Thereafter, the timing gear 11 is rotated and moved along the teeth of the timing gear 10 as shown by the arrow, the camshaft 7 is assembled into the bearing part 16, the cap 18 is closed and fixed, and the timing gear 11 is attached to the shaft part. Position against. At the same time, the marks 21 and 22 at the second point are matched to check timing alignment. That is, mark 21,
If marks 22 are not aligned, it means that the timing is not aligned, and if marks 21 and 22 are aligned, the timing is also aligned.Therefore, it is necessary to turn the timing gears 10 and 11 again. There will be no.

(Effects of the Invention) As is clear from what has been described above, according to the present invention, the timing alignment can be checked using the mark at the second point that meets when the assembly of both the intake and exhaust gears is completed. Therefore, there is no need to rotate both gears again, and the reliability of assembly accuracy can be ensured without increasing the number of man-hours.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram for explaining one embodiment of the method of the present invention, and FIG. 2 is a schematic structural diagram showing a valve drive mechanism of a type of engine to which the method of the present invention is applied. 6... Intake side camshaft, 7... Exhaust side camshaft, 10, 11... Timing gear, 19-24... Mark.

Claims (1)

[Claims] 1. 2 of the first point and the second point, respectively.
First fix one of the intake side gear and exhaust side gear with marks on its shaft, and then attach the other gear to that one gear with the marks at the first point on the other gear. Then, the other gear is rotated and moved along the teeth of the one gear, and when the other gear is positioned on its shaft, the marks at the second points of both gears are aligned. A method for assembling a camshaft drive gear of a twin cam valve system, which is characterized by the following: 2. The method of assembling a camshaft driving gear of a twin cam valve system according to claim 1, characterized in that marks having different design characteristics are used at the first point and the second point.