JP6818644B2 - Rotating shaft for engine - Google Patents

Description

The present invention relates to engine rotating shafts such as fuel camshafts and valve drive camshafts.

Fuel camshafts and valve drive camshafts used in industrial engines include a cam portion that is projected to push and drive the cam, and an inner fitting shaft portion that is internally fitted into a bearing. As such a conventional example, those disclosed in Patent Document 1 and Patent Document 2 are known.

For example, in the centrifugal governor of a diesel engine shown in Patent Document 1, a governor lever (1) is provided, and a rack pin (5) of a fuel injection pump (6) is connected to a start spring (2) via a first lever (1a). The governor weight (9) is interlocked and connected. A speed control lever (7) is connected to the second lever (1b) via a governor spring (8), and the tension of the governor spring (8) can be adjusted and operated by the speed control lever (7).

The fuel camshaft (15) that drives the fuel injection pump (6) is horizontally laid on the lower side of the fuel injection pump (6) substantially horizontally so as to be parallel to the fuel increase / decrease direction of the rack pin (5). A pump drive gear (16) incorporating a governor weight (9) is fixed to one end of the shaft (15).

In such a fuel camshaft, the corner of the cam portion (cam sliding portion) that comes into contact with the mating member is generally subjected to grinding and subsequent deburring in order to obtain a smooth sliding state. Met.

Japanese Patent Application Laid-Open No. 9-49440 Japanese Unexamined Patent Publication No. 2011-52571

In a high-load, high-speed engine, it is difficult to make the cam move more smoothly with less friction with the conventional cam shape by grinding and deburring, and the lubricity of the cam sliding part is improved and the fuel consumption is improved accordingly. Was leveling off.

An object of the present invention is to review the shape and structure of the cam portion through diligent research so that the frictional resistance with the mating member such as a tappet is reduced and the lubricity of the cam sliding portion can be improved. The point is to provide an improved rotating shaft for the engine.

The present invention relates to a rotary shaft for an engine.
It is provided with a support shaft portion 3 internally fitted in the bearing 7 and a cam portion 2 for pushing and driving the mating member 6 on the driven side, and is sandwiched between the pressing drive surface 2A and the side surface 2a of the cam portion 2. A tubular shape having a concavely curved inclined surface 9 following the pressing drive surface 2A having a constant width and a slight length in the axial center P direction following the minimum diameter of the inclined surface 9 on the entire circumference of the corner portion 8. It is characterized in that a composite stepped portion including the edge portion 12 of the above is formed .

The second invention relates to the rotary shaft for an engine according to the present invention.
The pressing drive surface 2A of the cam portion 2 is characterized in that a convex crowning process is applied.

The third invention relates to the rotary shaft for an engine according to the present invention or the second invention.
It is characterized in that it is applied to the fuel cam shaft 1.

According to the present invention, since the corner portion of the cam portion is provided with a concavely curved inclined surface, the lubricating oil is more easily held on the inclined surface by the surface tension when the engine speed is low. When the engine speed is high, the lubricating oil held on the inclined surface is scattered and the lubricating oil is sufficiently supplied to the sliding portion of the cam portion with the mating member to reduce friction and reduce friction loss. Becomes possible.

As a result, by reviewing the shape and structure of the cam part, the frictional resistance with the mating member such as the tappet is reduced, and the lubricity of the cam sliding part can be improved. A rotating shaft can be provided.

Front view with blowout diagram showing fuel camshaft of diesel engine Partially enlarged view showing the main part of the fuel cam shaft of FIG.

Hereinafter, a case where the embodiment of the rotary shaft for an engine according to the present invention is applied to a fuel cam shaft of various governors such as a mechanical type will be described with reference to the drawings.

As shown in FIG. 1, the fuel cam shaft 1 is formed on a pair of cam portions 2, 2 and a pair of support shaft portions 3, 3 and a support shaft portion 3 which are portions internally fitted in a bearing 7 such as a ball bearing. It is configured as a rotating shaft provided with flange portions 4, 4 and the like formed adjacent to each other. A drive shaft portion 5 having a diameter slightly smaller than that of the support shaft portion 3 is formed at one end of the fuel cam shaft 1.

The support shaft portion 3 and the flange portion 4 are locations having a circular cross section having a uniform diameter with respect to the shaft center P. The drive shaft portion 5 is also a portion having a circular cross section having a uniform diameter with respect to the shaft center P, except for a notch portion 5b such as a key groove. The pair of cam portions 2 and 2 are in contact with a mating member 6 such as a tappet, and have a known structure in which the mating member 6 is repeatedly pushed and driven as the fuel cam shaft 1 rotates.

In the fuel cam shaft (an example of an engine rotating shaft) 1, the cam portion 2 and the flange portion 4 are formed in a connecting shaft portion 10. Further, a connecting shaft portion 11 is formed between the pair of cam portions 2 and 2. The camshaft in the valve operating mechanism is also an example of a rotary shaft for an engine.

As shown in FIG. 2, concavely curved inclined surfaces 9 are formed on the corner portions 8 and 8 sandwiched between the pressing drive surface 2A and the side surface 2a and 2a of the cam portion 2. The side surface 2a on the flange portion 4 side is a slightly inclined substantially vertical surface, and the side surface 2a on the connecting shaft portion 11 side including the cam 11a for driving the feed pump is formed on the vertical surface. The pressing drive surface 2A is subjected to a convex crowning process in which the center is slightly larger (2 μm) in diameter than the left and right ends in the width direction (direction of the axis center P).

One corner portion 8 has a curved inclined surface 9 following the pressing drive surface 2A and a slight length in the axial center P direction following the minimum diameter of the curved inclined surface 9, as shown in the balloon diagram of FIG. It is formed in a composite stepped portion provided with a tubular edge portion 12. The other corner portion 8 has the same configuration as the other corner portion 8 except that the orientation in the axial center P direction is different.

As shown in FIG. 1, a concave recessed portion 14 including a portion having a diameter smaller than the diameter of the support shaft portion 3 is formed in the corner portion 13 on the flange portion 4 side of the support shaft portion 3. The concave slime portion 14 has an inclined peripheral surface 14a following the outer peripheral surface 3a of the support shaft portion 3, a bottom peripheral surface 14b having a diameter smaller than that of the support shaft portion 3, and an arc peripheral surface 14c following the side surface 4a of the flange portion 4. It is formed. The corner portion 13 is shown by one of the support shaft portions 3, but the other corner portion 13 has the same configuration except that the orientation in the axis center P direction is different, and the corresponding portions are designated by the same reference numerals. The explanation is omitted.

As shown in FIG. 1, a concave shaving portion 16 including a portion having a diameter smaller than the diameter of the drive shaft portion 5 is also formed in the corner portion 15 on the support shaft portion 3 side of the drive shaft portion 5. The concave shaving portion 16 has an inclined peripheral surface 16a following the outer peripheral surface 5a of the drive shaft portion 5, most of which has a smaller diameter than the drive shaft portion 5, and has a curved concave shape connecting the inclined peripheral surface 16a and the chamfered portion 3b of the support shaft portion 3. It is formed with a surface 16b.

Since curved inclined surfaces 9 which are concave surfaces are provided on both corner portions 8 and 8 of the cam portion 2, the lubricating oil is more easily held by the corner portions 8 when the engine speed is low. That is, at low rotation speeds, the lubricating oil is held on the curved inclined surface 9 by surface tension. Further, at high rotation speed, the lubricating oil held on the curved inclined surface 9 is scattered, and the lubricating oil on the sliding portion with the mating member 6 by the cam top (the portion most protruding in the radial direction of the shaft center P) is released. It will be sufficiently supplied, and it will be possible to reduce friction and reduce friction loss.

Since the cam portion 2 is subjected to a convex crowning process, even if the cam portion 2 and the tappet roller of the injection pump (an example of the mating member 6) are misaligned, the Hertz stress condition is relaxed. It is convenient to be able to do it.

Since the concave recessed portion 14 and the concave shaving portion 16 are provided in the corner portions 13 and 15 of the support shaft portion 3 and the drive shaft portion 5, more lubricating oil is held in the corner portions 13 and 15 when the engine speed is low. It becomes easy to be done. At high speeds, the lubricating oil held in the corners 13 and 15 is scattered and the lubricating oil is sufficiently supplied to the bearing 7 such as a ball bearing, and it is possible to reduce friction by fluid lubrication and reduce friction loss. become.

Therefore, even in a high-load, high-speed engine, the fuel cam shaft (rotary shaft) 1 can be smoothly rotated, and an effect that can improve the lubricity of the cam sliding portion and thereby improve the fuel efficiency can be obtained at a low price. There is. Since the chastity is improved, it is possible to improve the durability of the engine. Since the wear of the cam portion 2 can be reduced, the durability can be improved from this point as well.

[Another Embodiment]
A rotating shaft may have a structure in which the corner portion 8 is composed of only a concave curved inclined surface 9. Further, the shape and size of the inclined surface 9 can be changed in various ways.

1 Fuel camshaft 2 Cam part 2A Pressing drive surface 2a Side surface 3 Support shaft part 6 Mating member 7 Bearing 8 Square part 9 Inclined surface
12 Fuchibe
P-axis center

Claims (3)

A support shaft portion fitted inside the bearing and a cam portion for pushing and driving the mating member on the driven side are provided, and the entire circumference of the corner portion sandwiched between the pressing drive surface and the side surface of the cam portion is provided. , A composite stepped portion is formed having a concavely curved inclined surface following the pressing drive surface having a constant width and a tubular edge portion having a slight length in the axial center direction following the minimum diameter of the inclined surface. The rotating shaft for the engine.
The rotating shaft for an engine according to claim 1, wherein the pressing drive surface of the cam portion is subjected to a convex crowning process. The rotating shaft for an engine according to claim 1 or 2, which is applied to a fuel cam shaft.

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