JP2011169269A - Low noise gear structure in internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low noise gear structure in an internal combustion engine, requiring only a load required for driving a cam gear and not deteriorating fuel economy. <P>SOLUTION: The cam gear 3 is divided into an inner member 30 fixed to a camshaft 2 and an outer member 31 meshed with an idle drive gear 16, and a vibration damping member 33 increasing internal friction resistance and damping vibration is provided between the internal member 30 and the outer member 31. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a low noise gear structure in an internal combustion engine.

  In the internal combustion engine, the camshaft 2 is driven from the crankshaft 1 through a gear train 18 as shown in FIG. Since the valve mechanism shown in FIG. 5 is a DOHC (double overhead camshaft) type, there are two camshafts 2 (see, for example, Patent Documents 1 and 2).

JP-A-6-341307 Japanese Patent Laid-Open No. 10-184381

  By the way, in an internal combustion engine, the crankshaft 1 rotates with rotational fluctuation. Further, since the camshaft 2 also has a cam crest, the camshaft 2 rotates with rotational fluctuation. For this reason, the cam gears 3a and 4a (gears attached to the camshafts 2 and 2) and the idle drive gear 16 in FIG. 5 mesh with each other with rotational fluctuations. In general, there is a gap called backlash between the two meshing gears. For this reason, the cam gears 3a, 4a and the tooth surfaces of the idle drive gear 16 are repeatedly in collision while being in contact with or separated from each other. As a result, a so-called “tooth noise” is generated. In order to avoid this “tooth rattling noise”, there is a scissors gear 5 disclosed in Japanese Utility Model Publication Nos. 4-13467 and 5-71519.

  That is, as shown in FIGS. 6 and 7, the scissors gears 5 and 5a (the scissors gear 5a is the same as the scissors gear 5 and will be described below), the main gear 50 fixed to the camshaft 2, and the main gear 50 50, the sub-gear 51 having a smaller tooth width than the main gear 50 that is rotatable relative to the main gear 50, and the knock pins 52, 52 fixed to the back side of the mating surface of the main gear 50 and the sub-gear 51 (in FIG. 7, fixed to the sub-gear 51). Only the knock pin 52 is visible), and a notch ring-shaped torsion spring 53 engaged at both ends of the knock pins 52 and 52, and the main gear 50 and the sub gear 51 are provided by the elastic force of the torsion spring 53. And the idle drive gear 16 that meshes with them. It is one that is configured to remove backlash between.

  As described above, in the case of the scissors gear 5, the backlash is made zero by stretching the two gears including the main gear 50 and the sub gear 51 with the torsion spring 53.

  Therefore, a load obtained by adding a load by the spring (elastic force of the torsion spring 53) to the load necessary for driving the scissor gear 5 shown in FIG. 7 is applied to the gear tooth surface. Therefore, the frictional force generated on the tooth surface is increased by the amount of the spring load, resulting in a deterioration in fuel consumption.

  The present invention has been made in view of such points, and an object of the present invention is to provide a low noise gear structure in an internal combustion engine that can reduce friction on the tooth surface and improve fuel efficiency. is there.

  In order to solve the above problems, a low noise gear structure in an internal combustion engine of the present invention includes an idle drive gear driven from a crank gear via a gear train, and a cam gear that meshes with the idle drive gear and transmits rotation to the camshaft. An internal combustion engine having a low noise gear structure, wherein the cam gear is divided into an inner member fixed to the camshaft and an outer member meshing with the idle drive gear, and between the inner member and the outer member. In addition to increasing the internal frictional resistance, a vibration damping member for attenuating vibration is provided.

  Further, the vibration damping member may be formed by mixing rubber with either a 1-2 mm square cloth chip or a resin ball or metal ball having a diameter of about 1 mm.

  The vibration damping member includes a rubber shock absorbing member and a resin sliding member provided on one side of the shock absorbing member, and the sliding member is between the inner member and the outer member. It may be press-fitted.

  The vibration damping member has a plurality of slits intermittently along the circumferential direction inside the rubber ring member, and the ring member is connected to the inner member and the outer member so that the slits are in close contact with each other. It may be press-fitted in between.

  According to the above configuration, the cam gear rotating while meshing with the idle drive gear has the internal frictional resistance increased by the vibration damping member, the vibration is attenuated, and the “tooth rattling noise” is avoided.

  According to the present invention, friction on the tooth surface can be reduced and fuel consumption can be improved.

FIG. 1 is a schematic front view of an internal combustion engine. 2A and 2B are diagrams showing a cam gear according to an embodiment of the present invention, in which FIG. 2A is a front view and FIG. 2B is a cross-sectional view taken along line AA of FIG. 3A and 3B are views showing a cam gear according to another embodiment of the present invention, in which FIG. 3A is a front view and FIG. 3B is a cross-sectional view taken along line BB in FIG. 4A and 4B are diagrams showing a vibration damping member of a cam gear according to another embodiment of the present invention, wherein FIG. 4A is a front view of the vibration damping member, and FIG. 4B is a front view of the vibration damping member after being press-fitted into the cam gear. It is. FIG. 5 is a schematic front view showing an example of the internal combustion engine. FIG. 6 is a front view showing an example of the scissor gear in the internal combustion engine of FIG. 7 is a cross-sectional view taken along the line CC of FIG.

  A preferred embodiment of the present invention will be described with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected and demonstrated about the part similar to a prior art example.

  When the internal combustion engine is DOHC as shown in FIG. 1, the camshafts 2 and 2 are connected from the crank gear 10 of the crankshaft 1 through the idle gears 11 and 12, the sprocket 13, the chain 14, the sprocket 15, and the idle drive gear 16. The cam gears 3 and 4 are driven by rotation. In FIG. 1, 6 is a cylinder block, 8 is a cylinder head, 14a is a chain tension, 14b is a guide member, and 17 is an oil pump driving gear.

  As shown in FIG. 2, cam gears 3 and 4 (the cam gear 4 is the same as the cam gear 3, so the cam gear 3 will be described below) are teeth that mesh with the inner member 30 fixed to the camshaft 2 and the idle drive gear 16. The outer member 31 includes a vibration damping member 33 interposed between the inner member 30 and the outer member 31. The camshaft 2 is inserted through a shaft hole 32 formed at the center of the inner member 30, and the inner member 30 rotates together with the camshaft 2 via a key or the like (not shown).

  The vibration damping member 33 is, for example, rubber formed in a ring shape, and an inner peripheral surface 33a thereof is in contact with the outer peripheral surface 30a of the inner member 30, and an outer peripheral surface 33b is in contact with the inner peripheral surface 31a of the outer member 31. . For this reason, the inner member 30 and the outer member 31 are connected via the vibration damping member 33.

  If the vibration damping member 33 is made of only rubber, the internal loss (internal frictional resistance) is small. Therefore, resonance due to rotational fluctuation of the camshaft 2 may occur, and noise may be worsened. Therefore, mechanical rubbing is performed inside the rubber, for example, a rubbing member 35 such as a 1-2 mm square cloth chip or a resin ball or metal ball having a diameter of about 1 mm is mixed during the rubber kneading to mix the internal loss of the vibration damping member 33. Try to increase. As the resin, engineer plastic with a certain level of heat resistance is used.

  In the cam gear 3 configured as described above, the inner member 30 is attached to the camshaft 2, and the outer member 31 is engaged with the idle drive gear 16, so that rotation is transmitted from the crank gear 10.

  By the way, the vibration that becomes the source of the “tooth rattling sound” is generated by the collision of the tooth surface.

  According to the present embodiment, as shown in FIG. 2, the cam gear 3 is provided with the vibration damping member 33 between the inner member 30 and the outer member 31 to attenuate the vibration. Is done. Further, since the rubbing member 35 is mixed inside the vibration damping member 33, mechanical rubbing occurs inside the vibration damping member 33 when the rotation is transmitted from the crank gear 10, the internal friction resistance increases, and the camshaft 2 Resonance due to rotational fluctuations does not occur.

  FIG. 3 shows another embodiment of the present invention.

  In this embodiment, the vibration damping member 33 includes a ring-shaped rubber cushioning member 36 and a ring-shaped resin sliding member 37 provided on one side of the cushioning member 36. 37 is press-fitted between the inner member 30 and the outer member 31. As the resin, engineer plastic with a certain level of heat resistance is used. When the sliding member 37 is deformed while sliding between the inner member 30 and the outer member 31, it acts as a friction damper of the cam gear 3.

  In the present embodiment as well, when the rotation is transmitted, the sliding member 37 is deformed while sliding to increase the internal frictional resistance, and resonance due to rotational fluctuation of the camshaft 2 does not occur.

  FIG. 4 shows another embodiment of the present invention.

  In the present embodiment, the vibration damping member 33 has a plurality of slits 39 intermittently along the circumferential direction inside a rubber ring member 38, and the ring member 38 is connected to the inner member so that the slits 39 are in close contact with each other. It is press-fitted between 30 and the outer member 31. Round holes 39 a are formed at both ends of each slit 39. By pressing a rubber ring member 38 between the inner member 30 and the outer member 31, the slit 39 can be brought into close contact with each other, whereby a friction damper can be obtained.

  Also in this embodiment, the internal frictional resistance increases due to the sliding resistance of the closely-fitting slit 39 during rotation transmission, and resonance due to rotational fluctuation of the camshaft 2 does not occur.

  As described above, according to the present invention, it is only necessary to increase the internal frictional resistance and to provide the vibration damping member 33 for damping the vibration in a part of the gear, and the number of parts is smaller than that of the conventional scissor gear, and the assembly is easy. And cheap. Further, since the friction on the tooth surface is less than that of the scissor gear, fuel efficiency is improved.

  In addition, since the teeth are metal compared to a so-called resin gear using the entire gear as a resin, the teeth have high strength and can be used in places with high loads. In addition, since the strength of the resin itself does not need to be increased, it is not necessary to use an expensive resin.

  In addition, although demonstrated as a low noise gear structure (cam gear) in an internal combustion engine until now, this invention is not limited to this, You may use for any gear. Further, if there is rotational fluctuation, the effect of the present invention can be obtained even if the engine is not an internal combustion engine.

DESCRIPTION OF SYMBOLS 1 Crankshaft 2 Camshaft 3, 4 Cam gear 6 Cylinder block 8 Cylinder head 10 Crank gear 13, 15 Sprocket 16 Idle drive gear 30 Inner member 31 Outer member 33 Vibration damping member 35 Rubbing member 36 Buffer member 37 Sliding member 38 Ring member 39 Slit

Claims (4)

A low noise gear structure in an internal combustion engine comprising an idle drive gear driven from a crank gear via a gear train and a cam gear that meshes with the idle drive gear and transmits rotation to the camshaft,
Dividing the cam gear into an inner member fixed to the camshaft and an outer member meshing with the idle drive gear;
A low noise gear structure for an internal combustion engine, wherein a vibration damping member for increasing internal friction resistance and damping vibration is provided between the inner member and the outer member.   2. The low noise gear structure for an internal combustion engine according to claim 1, wherein the vibration damping member is made by mixing either a 1 to 2 mm square cloth chip or a resin ball having a diameter of about 1 mm or a metal ball with rubber.   The vibration damping member includes a rubber cushioning member and a resin sliding member provided on one side of the cushioning member, and the sliding member is press-fitted between the inner member and the outer member. 2. A low noise gear structure in an internal combustion engine according to claim 1.   The vibration damping member has a plurality of slits intermittently along the circumferential direction inside the rubber ring member, and the ring member is disposed between the inner member and the outer member so that the slits are in close contact with each other. 2. A low noise gear structure in an internal combustion engine according to claim 1, wherein the low noise gear structure is press-fitted into the internal combustion engine.

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