JPH05212681A - Tooth trace aligning jig of scissors gear - Google Patents

Abstract

PURPOSE:To enable a tooth trace to be accurately aligned in a job for aligning the tooth trace between a main gear and a sub gear in advance of engaging a scissors gear, made up of interposing a spring in space between both these main and sub gears as well as to make the setting work of this scissors gear easily performable. CONSTITUTION:A jig 15 for aligning a tooth trace is composed of a first 16 equipped with an engaging part 18 in mesh with a main gear 4 and a second member 17 equipped with an engaging part 19 in mesh with a sub gear 5, and both these members 16, 17 are correlated to each other free of relative movements so as to make these main and sub gears 4 and 5 relatively rotatable, and an adjusting means of an adjusting nut 21 or the like made up of making both these members 16, 17 into relative movements and holding the moving position, is installed in space between both these members 16 and 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention eliminates the backlash between gears, as in the case of transmitting the rotation of one camshaft to the other camshaft via a gear in a DOHC type internal combustion engine. The present invention relates to a jig for aligning the tooth traces of a main gear and a sub gear, which constitute a scissors gear, in a straight line when a scissors gear used for transmitting power is attached to a rotary shaft.

[0002]

2. Description of the Related Art In a DOHC type internal combustion engine, the rotation of a crankshaft is transmitted to one camshaft via a timing belt or a timing chain, and the rotation of one camshaft is transmitted to the other camshaft via a gear. In that case, the gear attached to the other cam shaft is configured as a scissors gear formed by superposing the main gear and the sub gear, and the main gear is inserted in the annular groove formed on the inner surface of the main gear. By inserting a C-shaped spring that biases the sub gear in the reverse direction, the main gear of the scissors gear can be attached to one of the cam shafts,
It is carried out with the backlash removed.

In order to attach the scissors gear to the rotary shaft such as the cam shaft and mesh with the mating gear as described above, the main gear and the sub gear in the scissors gear are
It is necessary to rotate the main gear and the sub-gear of the main gear in a straight line along the axial direction of the rotation shaft by relatively rotating them against the spring. Japanese Unexamined Patent Publication No. 60-237262 discloses that in FIG.
The means shown in FIG. 11 is proposed.

That is, this prior art is based on the scissors gear 4
A large-diameter guide hole 43 is formed in a portion between the ends of the spring 42 of the sub gear 41 constituting the main gear 4
4, a small-diameter engagement hole 45 is formed so as to be concentric with the guide hole 43 when the tooth traces of both gears 41 and 44 are aligned in a straight line. Then, a cam body 47 that fits into the guide hole 43 of the sub gear 41 is formed at one end of the adjusting jig 46, and the end surface of the cam body 47 is pinned in a state eccentric from the axial center of the cam body 47. 48 is provided so as to project, and a flat surface 49 is cut out at a portion of the outer peripheral surface of the cam body 47 located on the opposite side of the pin 49 with the axial center of the cam body 47 interposed therebetween. With the cam body 47 of the jig 46 inserted into the guide hole 43 of the sub gear 41 and the pin 48 inserted into the engagement hole 45 of the main gear 44 in a state where the cam body 47 of the jig 46 is held non-rotatably, Rotate the jig 46 in the direction of arrow A by a certain angle θ,
By utilizing the lever principle, only the sub gear 41 is rotated against the spring 42 so that the tooth traces of the main gear 41 and the scissors gear 44 are aligned.

[0005]

However, in this prior art, the angle θ at which the sub gear 41 rotates relative to the main gear 44 is such that the pin 48 of the jig 46 is eccentric from the axial center of the cam body 47. It is regulated to be constant according to the distance, and the angle at which the sub gear 41 rotates with respect to the main gear 44 cannot be adjusted to an arbitrary value. Therefore, if an error occurs in the drilling position of the guide hole 43 or the engaging hole 45, However, there is a problem that the tooth traces of the main gear 44 and the sub gear 41 cannot be aligned accurately. To avoid this problem, the guide hole 43 and the engagement hole 45 must be machined with high accuracy. However, the manufacturing cost of the scissors gear 40 increases.

Further, the sub gear 4 is rotated by rotating the jig 46.
It is necessary to keep the main gear 44 in a non-rotatable state due to the moment about the shaft center acting on the main gear 44 and the main gear 44. For this purpose, for example, the main gear 44 is fitted on the rotary shaft 51. Then, in that state, main gear 4
4 has to be meshed with the mating gear 50, which makes it difficult to attach the scissors gear 40.

According to the present invention, it is possible to accurately align the tooth traces of the main gear and the sub-gear without special processing of the scissors gear, and at the same time, to provide a jig which facilitates the attachment of the scissors gear. It is intended to be provided.

[0008]

In order to achieve this object, the present invention provides a main gear in a scissors gear comprising a main gear and a sub gear, which are superposed on each other, and a spring for urging the both gears in a reverse direction. A first member having an engaging portion that meshes with the second gear, and a second member having an engaging portion that meshes with the sub gear. Both of these members can relatively rotate the main gear and the sub gear. Thus, the adjusting means is provided so as to be relatively movable and to hold the moving position between the both members by relatively moving them.

[0009]

According to this structure, the adjusting means is operated with the engaging portion of the first member engaged with the main gear and the engaging portion of the second member engaged with the sub gear, respectively. By relatively moving the two members and rotating the sub gear and the main gear relative to each other by an arbitrary angle against the spring, the main gear and the sub gear are brought into a state where their tooth lines are accurately aligned. Can be held.

Then, the main gear and the sub gear are meshed with the mating gear while the teeth are aligned with the jig, or the teeth of the main gear and the sub gear are aligned with the jig, The main gear and the sub gear are once fastened with a fixing bolt, and in that state, they are meshed with the mating gear and then the fixing bolt is removed, whereby the scissors gear can be meshed with the other gear.

[0011]

As described above, according to the present invention, the sub gear and the main gear can be relatively rotated at an arbitrary angle without performing any special processing on the sub gear and the main gear. It is possible to accurately align the tooth traces of the main gear and the sub gear in the scissors gear without increasing the manufacturing cost, and to relatively rotate both gears while meshing with the main gear and the sub gear. However, since it is not necessary to hold the main gear in a non-rotatable manner when aligning teeth, it is possible to attach the scissors gear very easily.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment in which the present invention is applied to a scissors gear in a camshaft of a DOHC type internal combustion engine will be described with reference to the drawings. 1 to 7 show a first embodiment, and in these drawings, reference numeral 1 denotes an exhaust side cam shaft having a plurality of cam portions 1a for opening and closing an exhaust valve (not shown) formed therein. As shown, a large-diameter portion 1a having a collar 2 is formed at a position near one end of the exhaust-side camshaft 1, and the large-diameter portion 1b is
The main gear 4 and the sub gear 5 are superposed on each other, and the scissors gear 3 is fitted so that the outer surface of the main gear 4 is in contact with the collar 2.
Are held by a snap ring 6 engaged with the large diameter portion 1b of the exhaust side cam shaft 1 so as not to come off.

The main gear 4 in the scissors gear 3
Is non-rotatably fitted to the exhaust side cam shaft 1 by the key 7, while the sub gear 5 is rotatably fitted to the exhaust side cam shaft 1 and is annularly attached to the inner surface of the main gear 4. A groove 8 is formed, and a C-shaped spring 9 is inserted into the annular groove 8. One end surface of the spring 9 is attached to the first stopper pin 10 fixed to the main gear 4, and the other end surface of the spring 9 is attached to the sub gear 5. The main gear 4 and the sub gear 5 are rotated in the reverse direction by the spring 9 while being in contact with the second stopper pins 11 fixed to the main gear 4 and the sub gears 5 with the tooth traces 4a and 5a aligned in a straight line. I am trying to be relatively urged.

A through hole 13 for a temporary fixing bolt 12 is formed in a portion of the sub gear 5 between both ends of the spring 9, and a portion of the main gear 4 between both ends of the spring 9 is formed. A female screw hole 14 is formed so as to be substantially concentric with the through hole 13 of the sub gear 5 when the tooth traces 4a of the main gear 4 and the sub gear 5 are aligned. Code 15
Is the tooth traces 4a, 5 of the main gear 4 and the sub gear 5.
A jig for aligning a is shown. The jig 15 is a hollow rectangular first member 16 provided with a downward grip 16a, and is non-rotatably fitted in the first member 16 so as to be slidable back and forth. The second member 17 having a rectangular cross section is provided.

At the tip of the first member 16, the first member 1
7 is provided with a protrusion 16b that extends downward substantially orthogonally to
A fan-shaped engaging portion 18 having a plurality of teeth meshing with the main gear 4 in the lateral direction is fixedly formed at the lower end of the protruding portion 16b, while the sub gear 5 is provided at the tip of the second member 17.
An engaging portion 19 having a plurality of teeth that mesh with each other from above is fixedly formed, and a screw shaft 20 is further provided at the rear end of the second member 17.
An adjusting nut 21 as an example of adjusting means is screwed onto the screw shaft 20 so as to protrude from the rear end of the first member 16, and the adjusting nut 21 is inserted through a thrust bearing 22. It touches the rear end face.

To the first member 16 (or the second member 17), a tooth trace gauge 23 which is fitted tightly to the main gear 4 and the sub gear 5 is attached by a string 24. In the above configuration, the main gear 4 and the sub gear 5 are previously fitted to the large diameter portion 1b of the exhaust side cam shaft 1 before being attached to the cylinder head 25, and these are locked by the snap ring 6, First member 16 in jig 15
Of the second member 17 is engaged with the main gear 4, and the engaging portion 19 of the second member 17 is engaged with the sub gear 5. The adjusting nut 21 is rotated in this state to retract the first member 17, 1
7 is brought closer to the engaging portion 18 of the first member 16 and the sub gear 5 is rotated against the main gear 4 against the spring 9, whereby the main gear 4 and the sub gear 5 are rotated.
It is possible to align the tooth lines 4a and 5a of and with each other as shown in FIG. 6 to be aligned with each other as shown in FIG.

Then, a tooth trace gauge 23 is meshed with the main gear 4 or the sub gear 5 and is slid in the axial direction of the exhaust side cam shaft 1 as shown by an arrow B in FIG. After confirming whether the tooth lines 4a, 5a of 4,5 are aligned, the main gear 4 and the sub gear 5 are fastened by screwing the temporary fixing bolt 12 into the female screw hole 14 of the main gear 4. Then, as shown in FIG. 4, the exhaust side cam shaft 1 is mounted on the cylinder head 25 so that the scissors gear 3 meshes with the gear 27 of the intake side cam shaft 26, and then the exhaust side cam shaft 1 is supported. By attaching the cap 27 to the cylinder head 25 and then removing the temporary fixing bolt 12, the exhaust side camshaft 1
Is installed.

It should be noted that the main gear 4 and the sub gear 5 are not fastened with the temporary fixing bolts 12 and the jigs 15 keep the teeth 4a, 5a of the main gear 4 and the sub gear 5 aligned. The exhaust side cam shaft 1 may be attached to the cylinder head 25. As shown in FIG. 8, the scissors gear 3 includes a main gear 4 and a boss 4 having a small diameter.
There is a configuration in which the sub gear 5 is rotatably fitted to the boss portion 4b and is locked by the washer 28 and the snap ring 6 in this case. In this case, the scissors gear is used. Before attaching 3 to the exhaust side camshaft 1,
After the tooth lines 4a and 5a of both gears 4 and 5 are aligned with the jig 15 and both gears 4 and 5 are fastened with the temporary fixing bolt 12, the scissors gear 3 is attached to the exhaust side camshaft 1. It may be attached.

As shown in FIG. 9, two guide pins 30 are provided on the first member 16 while the second member 17 is provided with the guide pins 30.
An arc-shaped elongated hole 31 to be fitted into the guide pin 30 of the book is formed, and a holding portion 16c provided at the rear end of the first member 16 is further provided.
As an example of the adjusting means, an adjusting bolt 32 with a photograph 32a is rotatably and non-slidably attached, and the adjusting bolt 32 is non-rotatably attached to a support portion 17a protruding upward from the second member 17. By screwing on the locked nut 33,
By rotating the adjusting bolt 32, the sub gear 5 and the main gear 4 can be relatively rotated by an arbitrary angle.

In the present invention, instead of the first member and the second member being slidable relative to each other, for example,
Both members are formed in a rod shape, and a midway portion along the longitudinal direction is pivotally rotatably supported by a pin, and an engaging portion that meshes with the main gear or the sub gear is formed at one end of each member. On the other hand, the other ends of both members are connected by adjusting means such as bolts, and the rotation angle of both members is changed by adjusting means such as bolts, so that the main gear and the sub gear are relatively rotated. Further, the adjusting means is not limited to the screw type as in the embodiment, and other mechanism such as a hydraulic cylinder may be adopted.

[Brief description of drawings]

FIG. 1 is a partially cutaway side view showing a first embodiment.

FIG. 2 is a plan view of FIG.

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

FIG. 4 is a diagram showing a usage state.

FIG. 5 is an exploded perspective view of a scissors gear.

FIG. 6 is a perspective view of the scissors gear in a state where the tooth lines are displaced.

FIG. 7 is a perspective view of the scissors gear in a state where the tooth lines are aligned.

FIG. 8 is a vertical cross-sectional side view of another embodiment of a scissors gear.

FIG. 9 is a side view showing another embodiment.

FIG. 10 is a diagram showing a conventional technique.

FIG. 11 is a perspective view of a main part of a conventional jig.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 rotating shaft (exhaust side camshaft of DOHC type internal combustion engine) 3 scissors gear 4 main gear 5 subgear 4a, 5a toothed line 6 snap ring 12 temporary fixing bolt 15 jig 16 first member 17 second member 18, 19 engagement Joint part 20 Screw shaft 21 Adjustment nut 32 Adjustment bolt

Claims (1)

[Claims] 1. A first member having an engaging portion that meshes with the main gear in a scissors gear, which is formed by interposing a spring for biasing the main gear and the sub gear, which are superposed on each other, in a reverse direction. A second member having an engaging portion that meshes with the sub gear, and these two members are movably associated with each other so as to relatively rotate the main gear and the sub gear. A jig for aligning tooth traces of a scissors gear, characterized in that an adjusting means is provided so as to relatively move the both members and hold the moving position.