JPH0989083A - Lubricating structure for scissors gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a pressure drop in an oil system from being caused, by forming a supply oil hole of an overlapping surface of a main gear with a subgear in a large diameter as compared with a hole diameter supplying a necessary supply amount of oil, controlling a supply amount by an orifice, and stably ensuring the necessary supply amount of oil. SOLUTION: A scissors gear 1 is constituted by a main gear 2 and a subgear 3, this main gear 2 is press fitted to a scissors gear fitting part 6 of a camshaft 5 also brought into contact with a flange part 7, with positioning performed in the axial direction, the subgear 3 is fitted rotatably to the scissors gear fitting part 6 of the camshaft 5 further in a manner overlapping with the main gear 2. A supply oil hole 12 is formed in the radial direction so as to make an opening end appear in an overlapping surface of the main gear 2 with the subgear 3, an orifice 13 is arranged in a communication part between this supply oil hole 12 and an oil pasage 11, the supply oil hole 12 is formed in a large diameter as compared with a hole diameter supplying a necessary supply amount of oil, and a supply amount of oil is controlled by the orifice 13. Accordingly, the necessary supply amount of oil can be stably ensured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricating structure for a scissors gear such as a scissors gear provided for synchronously rotating two cam shafts in a DOHC engine, which transmits rotation without backlash.

[0002]

2. Description of the Related Art In a DOHC engine, as shown in FIG. 4, the rotation of a crankshaft 21 is transmitted to one camshaft 23 via a chain 22 or a timing belt, and the rotation of one camshaft 23 is transmitted to the other. It is configured to be transmitted to the cam shaft 24 via a pair of gears 25 and 26. In this case, the drive gear 25 attached to the one cam shaft 23 and the driven gear 26 attached to the other cam shaft 24.
Since it is necessary to perform the mesh rotation with the backlash removed, a scissors gear is used as the driven gear 26. 27 is a direct-type overhead cam mechanism.

A concrete example of the scissors gear will be described with reference to FIGS. 5 and 6. Reference numeral 5 denotes a cam shaft corresponding to the driven cam shaft 24, and a scissors gear 1 having a main gear 2 and a sub gear 3 at one end thereof. Are fitted. Main gear 2
With the sub gear 3 overlapping, the collar 7 and the snap ring 1
7, the main gear 2 is non-rotatably engaged with the cam shaft 5 by the key 16. An annular groove 8 is formed on the inner side surface of the main gear 2, and a C-shaped spring 18 is housed and arranged therein. One end of the spring 18 is in contact with the first stopper 19 on the main gear 2 side, and the other end of the spring 18 is in contact with the second stopper 20 on the sub gear 3 side, so that the sub gear 3 is located at a position where the teeth of the main gear 2 and the sub gear 3 are aligned. 6 to 6 are configured to urge the gears in the rotational direction as indicated by the arrow.

A driven gear 26 composed of the seed gear 1 is also provided.
When the gear is engaged with the drive gear 25, the screw holes 31 and the bolt holes 32 are provided at positions between both ends of the spring 18 in the main gear 2 and the sub gear 3 in order to temporarily fix the main gear 2 and the sub gear 3 by aligning the teeth. And a temporary fixing bolt 33 is provided.

In the scissors gear 1 having the above-mentioned structure, the main gear 2 is fixedly provided on the cam shaft 5, but the sub gear 3 rotates relatively to the cam shaft 5 and the main gear 2 even though the sub gear 3 has a small angle. It is necessary to lubricate the sliding surface by lubrication, and it is necessary to lubricate the annular groove 8 in order to ensure the smooth operation of the spring 18 in the annular groove 8.
Further, it is of course necessary to refuel and lubricate the meshing portion of the driven gear 26 composed of the scissors gear 1 and the drive gear 25.

Therefore, for example, in Japanese Utility Model Publication No. 4-37214, the oil pump 2 is attached to the camshaft 24 as shown in FIG.
7 is provided with an oil passage 28 in the axial direction communicating with 7, and an oil supply hole 29 is provided so that the opening end of the oil passage 28 in the radial direction faces the overlapping surface of the main gear 2 and the sub gear 3. There is disclosed a lubricating device in which a communication passage 30 that communicates 29 with the annular groove 8 is provided, and oil is supplied to the meshing portion from the oil passage 28 through the oil supply hole 29, the communication passage 30, and the annular groove 8.

As a lubricating device of this type, as shown in FIG. 8, a ball 10 is press-fitted into the end of a hollow hole 9 formed in the shaft core of the cam shaft 5 to form an oil passage 11, and a scissors gear fitting portion 6 is provided. It is known that the superposed surfaces of the main gear 2 and the sub gear 3 are lubricated by forming a radial lubrication hole 12 from the outer periphery toward the oil passage 11 at a position at an appropriate distance from the collar portion 7 in FIG. There is.

[0008]

However, in the lubricating device as described above, as shown in FIG. 9, the thickness of the main gear 2 is increased while the main gear 2 is press-fitted so as to come into contact with the collar portion 7. The degree of covering of the main gear 2 with respect to the oil supply hole 12 differs due to variations in the size, press-fitting accuracy, distance from the collar portion 7 to the oil supply hole 12, and the like, and as shown in FIG. It may be blocked by the main gear 2 or, as shown in FIG.
Most of the 2 may be open. Therefore, when the diameter of the oil supply hole 12 is small, there is a problem that the effective area of the oil supply hole 12 varies largely due to the processing accuracy and the gear press-fitting accuracy as described above, and the amount of oil supply also varies. On the other hand, if the diameter of the oil supply hole 12 is increased in order to solve such a problem, the pressure of the oil system decreases, and particularly when the engine oil is used as the lubricating oil, the engine is adversely affected. There is a problem.

In view of the above conventional problems, the present invention has an object to provide a scissor gear lubrication device which can stably secure a necessary amount of oil supply and does not cause a pressure drop in the oil system. And

[0010]

SUMMARY OF THE INVENTION According to the present invention, a main gear non-rotatably fitted to a rotary shaft and a sub gear rotatably fitted to the rotary shaft are superposed and combined with each other, and both gears are urged to rotate in opposite directions. Is a lubrication structure of a scissors gear with a spring interposed, and is formed in a radial direction such that an axial end oil passage communicating with an oil pump and an opening end face the overlapping surface of the main gear and the sub gear. The dimensional accuracy is low because the oil supply hole and the orifice provided in the communication part of the oil supply hole and the oil passage are provided, and the oil supply hole is formed to have a diameter larger than the diameter of the hole for supplying the required amount of oil supply. However, the required amount of oil supply was always secured, and the amount of oil supply was controlled by the orifice so that the pressure in the oil system would not drop.

[0011]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described below with reference to FIGS. Since the disposition state of the scissors gear and the overall configuration thereof are the same as those of the conventional example described with reference to FIGS. 4 to 6, the description thereof will be omitted and the description thereof will be omitted.

In FIG. 1, 1 is a scissors gear,
It is composed of a main gear 2 and a sub gear 3. The main gear 2 is a scissors gear fitting portion 6 of a cam shaft 5 which is a rotating shaft.
It is press-fitted in, and is brought into contact with the flange portion 7 to be positioned in the axial direction, and is rotatably coupled to the cam shaft 5 by a key (not shown). The sub gear 3 is rotatably fitted to the scissors gear fitting portion 6 of the cam shaft 5, and thus is relatively rotatable with respect to the main gear 2, and is fitted so as to overlap the main gear 2. Further, the sub gear 3 is provided in the annular groove 8 formed on the overlapping surface of the main gear 2 and the sub gear 3.
Means (not shown) for urging the main gear 2 to rotate in the rotation direction of the main gear 2 is incorporated.

A hollow hole 9 is formed in the shaft core of the cam shaft 5, and the tip of the hollow hole 9 is closed by a ball 10,
An oil passage 11 that communicates with an oil pump (not shown) is formed. In the scissors gear fitting portion 6, an oil supply hole 12 is bored in the radial direction so that the opening end 12a faces the overlapping surface of the main gear 2 and the sub gear 3. This lubrication hole 1
2 is formed as a hole having a diameter larger than the hole diameter required to supply the required amount of oil supply, and is drilled only up to the front position communicating with the oil passage 11. The inner end of the oil supply hole 12 and the oil passage 11 are communicated with each other via an orifice 13 that controls the amount of oil supply. In the example shown in FIG. 1, the orifice 13 is composed of a small diameter hole 14, and the hole diameter does not reduce the oil pressure of the oil system communicating with the oil passage 11 and is the amount of oil necessary for lubricating the sub gear 3. Is set to the minimum hole diameter required to supply
Is set to a larger diameter than that. For example, even if the diameter of the small diameter hole 14 determined by the required oil amount is 1 mm, the oil supply hole 12 is set to have a diameter of about 3 mm.

According to the above construction, the orifice 13 is provided in the communicating portion between the oil supply hole 12 and the oil passage 11, and the amount of oil supply is controlled by this orifice 13, so that the oil supply hole 12 has a large diameter. However, it does not cause a pressure drop in the engine oil system. Further, since the oil supply hole 12 is formed to have a larger diameter than the hole diameter for supplying the required amount of oil supply,
Since the processing accuracy such as the thickness of the main gear 2 and the distance from the flange portion 7 to the axial center position of the oil supply hole 12 and the press-fitting accuracy of the main gear 2 are low, for example, as shown in FIG. Even if there is some variation in the closed area of the oil supply hole 12 due to the main gear 2 such that the degree of covering the hole 12 becomes large enough to completely close it if it is a small diameter hole 14, it is used as the opening area of the oil supply hole 12 for oil supply. A sufficient area can be secured. Therefore, it is possible to stably secure the amount of oil supply required for lubricating the sub gear 3 without lowering the pressure of the engine hydraulic system.

Further, since the large diameter oil supply hole 12 is filled with the lubricating oil and the orifice 13 serving as a passage resistance is interposed between the oil supply hole 12 and the oil passage 11,
Even after the oil pump is stopped, a large amount of lubricating oil remains in the large-diameter oil supply hole 12, and as a result, when the camshaft 5 rotates when the engine is started, the oil is not supplied to the oil passage 11. Even in the stage, the lubricating oil in the oil supply hole 12 can be supplied to the scissors gear 1 by the centrifugal force generated by the rotation of the cam shaft 5. Therefore, the scissors gear 1 can be lubricated even at the initial stage of engine startup.

The orifice 13 is not limited to the small-diameter hole 14 shown in FIG. 1, but as shown in FIG. 3, a separate orifice member 15 is fitted to the communicating portion between the oil supply hole 12 and the oil passage 11. You may comprise. However, the orifice 13
If the small-diameter hole 14 is used, it is not necessary to prepare the orifice member 15 and press-fit it into the oil supply hole 12, and the hole can be formed by the same hole processing as the oil supply hole 12, so that the structure can be constructed at low cost.

[0017]

According to the lubrication structure of the scissors gear of the present invention, the oil supply hole formed in the radial direction so that the opening end faces the overlapping surface of the main gear and the sub gear as described above is a hole for supplying a necessary oil supply amount. By forming a larger diameter than the diameter,
The required lubrication area can be secured even if there is some variation in the closed area of the lubrication hole due to the main gear due to the processing accuracy and press-fitting accuracy of the main gear, and lubrication is provided by the orifice provided in the communication part between this lubrication hole and the oil passage. Since the amount is controlled, it is possible to stably secure the required amount of oil supply without causing a pressure drop in the oil system. Also,
When the cam shaft rotates, the lubricating oil in the oil supply hole is supplied to the scissors gear by centrifugal force, so that the scissors gear can be lubricated even at the initial stage of engine startup.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a main part of a scissors gear lubricating device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a closed state of a fuel supply hole by a main gear in the same embodiment.

FIG. 3 is a cross-sectional view showing another form of the orifice in the same embodiment.

FIG. 4 is a perspective view showing how scissors gears are arranged in the engine.

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

FIG. 6 is a perspective view of a scissors gear.

FIG. 7 is a vertical cross-sectional view of a lubricating device for a conventional zipper gear.

FIG. 8 is a vertical cross-sectional view of a main part of a conventional scissors gear lubrication device.

FIG. 9 is a vertical cross-sectional view of a main part showing a fitted state of a main gear in a conventional jigs gear.

FIG. 10 is an explanatory diagram of causes of variations in the amount of oil supply in the conventional example.

[Explanation of symbols]

 1 Scissors gear 2 Main gear 3 Sub gear 5 Cam shaft (rotary shaft) 11 Oil passage 12 Oil supply hole 13 Orifice

Claims (1)

[Claims] 1. A scissors gear in which a main gear non-rotatably fitted to a rotation shaft and a sub gear rotatably fitted thereto are superposed and combined with each other, and a spring is interposed between the two gears to urge them in opposite directions. The lubrication structure includes an oil passage in the axial direction communicating with the oil pump, a lubrication hole formed in the radial direction so that the opening end faces the overlapping surface of the main gear and the sub gear, and an oil supply hole. An orifice provided at the communicating portion of the oil passage is provided, and the oil supply hole is formed to have a diameter larger than the hole diameter for supplying the required oil supply amount, and the oil supply amount is controlled by the orifice. Lubrication structure for scissors gear.