JP5028300B2 - Engagement structure of a pair of gears in balance shaft mechanism - Google Patents

Description

  The present invention relates to a meshing structure of a pair of gears in a balance shaft mechanism.

In a balancer mechanism or the like used in a reciprocating engine, one of the gears to be driven is made of metal, and the tooth surface of the other gear to be driven is reduced for the purpose of reducing gear noise (noise generated by gear meshing). Resin is used.
For example, in the gear mechanism of the power transmission system of Patent Document 1, a second gear having a resin tooth surface is meshed with a metal first gear, and a damping mechanism provided on the second gear is used. This suppresses the occurrence of a resonance phenomenon associated with the meshing of the gears.

In the conventional meshing structure of a pair of gears, the pressure angle of any gear is a standard pressure angle such as 20 °.
However, when an input torque due to the output of the engine is applied to the drive side gear, the tooth tip portion of the tooth surface of the drive side gear strongly contacts the tooth bottom portion of the tooth surface of the driven gear. Therefore, the wear of the resin tooth surface in the driven gear increases, and the tooth width (thickness) has to be increased.

JP 2001-193794 A

  The present invention has been made in view of such conventional problems, and has a meshing structure of a pair of gears in a balance shaft mechanism capable of improving the durability reliability of a driven side gear having a resin tooth surface. It is something to be offered.

A first aspect of the invention includes a drive side gear provided on a crankshaft of a reciprocating engine, and a driven gear for rotating a pair of balance shafts in a driven manner, and a resin tooth surface meshing with the drive side gear. In the meshing structure with
The pressure angle of the drive-side gear is larger than the pressure angle of the driven-side gear, and there is an engagement structure of a pair of gears in the balance shaft mechanism.

  In the meshing structure of the pair of gears of the present invention, the pressure angle of the drive side gear provided on the crankshaft is made larger than the pressure angle of the driven side gear provided on the balance shaft. As a result, even when an input torque due to engine output is applied to the drive side gear, only the tooth tip portion of the tooth surface of the drive side gear is locally strongly applied to the tooth bottom portion of the tooth surface of the driven gear. The contact can be eased. Therefore, the wear of the resin tooth surface in the driven gear can be reduced.

  Therefore, according to the meshing structure of the pair of gears in the balance shaft mechanism of the present invention, it is possible to improve the durability reliability of the driven side gear provided with the resin tooth surface.

A second aspect of the invention includes a metal drive side gear provided on one balance shaft that rotates following the rotation of a crankshaft of a reciprocating engine, and a resin tooth surface that meshes with the drive side gear, In the meshing structure with the driven side gear for driven rotation of the balance shaft of
The pressure angle of the drive-side gear is larger than the pressure angle of the driven-side gear, and there is an engagement structure of a pair of gears in the balance shaft mechanism (claim 2).

  In the meshing structure of a pair of gears of the present invention, the pressure angle of the drive side gear provided on one balance shaft is made larger than the pressure angle of the driven side gear provided on the other balance shaft. As a result, even when an input torque due to engine output is applied to the drive side gear, only the tooth tip portion of the tooth surface of the drive side gear is locally strongly applied to the tooth bottom portion of the tooth surface of the driven gear. The contact can be eased. Therefore, the wear of the resin tooth surface in the driven gear can be reduced.

  Therefore, the durability reliability of the driven gear provided with the resin tooth surface can be improved also by the meshing structure of the pair of gears in the balance shaft mechanism of the present invention.

A preferred embodiment in the first and second inventions described above will be described.
In the first and second inventions, the pressure angle refers to a tilt angle of the tooth surface, and is an angle formed by a radial line and a tangent to a point on the reference pitch circle on the tooth surface (effect of meshing pressure). The angle formed by the line and the tangent line of the reference pitch circle) (see FIG. 5).
The pressure angle of the drive side gear can be 0.2 to 0.6 ° larger than the pressure angle of the driven side gear.
Alternatively, when the pressure angle of the drive-side gear is larger than the pressure angle of the driven-side gear, the circumferential length (refer to the dimension line L in FIG. 5) of the tooth surface of the drive-side gear is set to the driven side. It can be formed 20 to 50 μm shorter than the circumferential length of the tooth edge of the gear.

  Further, as the input torque to the drive side gear is set larger, the amount by which the pressure angle of the drive side gear is made larger than the pressure angle of the driven side gear can be set larger. In addition, the driven gear with a resin tooth surface is deformed by heat, so the amount of pressure on the drive gear is set larger than the pressure angle of the driven gear in consideration of thermal deformation. can do.

The driven gear may be a standard gear having a pressure angle of 20 °, and the drive gear may be a gear having a pressure angle larger than that of the standard gear. ).
In this case, by adjusting the pressure angle of the drive side gear, it is possible to easily form a state where the pressure angle of the drive side gear is larger than the pressure angle of the driven side gear.
In addition, the driven gear can be composed of gears having various pressure angles other than the above.

The drive side gear may be a standard gear having a pressure angle of 20 °, and the driven side gear may be a gear having a smaller pressure angle than the standard gear. ).
In this case, a state where the pressure angle of the drive side gear is larger than the pressure angle of the driven side gear can be easily formed by adjusting the pressure angle of the driven side gear.
In addition to the above, the drive side gear can be composed of gears having various pressure angles.

In the following, an embodiment according to the meshing structure of a pair of gears in the balance shaft mechanism of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 to 4, the meshing structure of the pair of gears in the balance shaft mechanism 1 of the present example includes a metal drive side gear 12 provided on the crankshaft 11 of the reciprocating engine 10 and a drive side gear 12. This is a meshing structure with a driven gear 3 that is provided with a meshing resin tooth surface and is driven to rotate the pair of balance shafts 4. In this meshing structure, as shown in FIG. 5, the pressure angle α <b> 1 of the drive side gear 12 is made larger than the pressure angle α <b> 2 of the driven side gear 3.
As shown in the figure, the pressure angles α1 and α2 are angles formed by the radius line R and the tangent line A to the point on the reference pitch circle C on the tooth surface (the line of action B of the engagement pressure and the reference line). The angle formed by the tangent line D of the pitch circle C).

Below, it explains in full detail with reference to FIGS. 1-6 about the meshing structure of a pair of gear in the balance shaft mechanism 1 of this example.
As shown in FIGS. 1 to 4, the meshing structure of the pair of gears of this example is employed in the balance shaft mechanism 1 used for reducing the occurrence of secondary vibration of the reciprocating engine 10. The balance shaft mechanism 1 is configured to support a pair of balance shafts 4 that rotate following the rotation of the crankshaft 11 of the reciprocating engine 10 so as to be rotatable with respect to the housing 2. The pair of balance shafts 4 includes a gear 41 that rotates in mesh with each other, and a balance weight 42 that forms an eccentric load. The housing 2 is formed with a bearing portion 21 that rotatably supports the shaft portions 43 of the pair of balance shafts 4.

The drive side gear 12 in the crankshaft 11 of this example, the driven side gear 3 in one balance shaft 4A, and the pair of gears 41 are all constituted by helical gears (helical gears). The driven gear 3 of this example is entirely made of resin. The driven gear 3 may be formed by fitting or coupling a resin outer peripheral portion having a tooth surface to a metal inner peripheral portion.
In order to reduce gear noise, one gear 41A provided on one balance shaft 4A provided with the driven gear 3 is made of metal, and the other gear 41B provided on the other balance shaft 4B is made of resin. It is. The other gear 41B may be formed by fitting or coupling a resin outer peripheral portion having a tooth surface to a metal inner peripheral portion.

Further, in this example, as shown in FIG. 5, by adjusting the pressure angle α1 of the drive side gear 12, a state in which the pressure angle α1 of the drive side gear 12 is larger than the pressure angle α2 of the driven side gear 3 is formed. did. That is, the driven side gear 3 of this example is composed of a standard gear having a pressure angle α2 of 20 °, and the drive side gear 12 of this example is a gear having a pressure angle α1 larger than that of the standard gear. It is composed of
In the figure, in the drive side gear 12, each tooth surface of the standard gear is indicated by a two-dot chain line P, and a state where the pressure angle α1 is increased is indicated by a solid line Q. By increasing the pressure angle α1 of the tooth surface of the drive side gear 12 at the tooth edge portion (near the point a in the figure) of the tooth surface of the drive side gear 12 existing at the terminal portion of the meshing action line B, It can be seen that it is difficult for the tooth edge of the tooth surface and the tooth surface of the driven gear 3 to come into contact with each other.

On the other hand, as shown in FIG. 6, the state in which the pressure angle α1 of the drive side gear 12 is larger than the pressure angle α2 of the driven side gear 3 is also formed by adjusting the pressure angle α2 of the driven side gear 3. Can do. In this case, the drive side gear 12 may be configured from a standard gear having a pressure angle α1 of 20 °, and the driven side gear 3 may be configured from a gear having a pressure angle α2 smaller than that of the standard gear. it can.
In the figure, in the driven gear 3, each tooth surface of the standard gear is indicated by a two-dot chain line X, and a state where the pressure angle α2 is reduced is indicated by a solid line Y. By reducing the pressure angle α2 of the tooth surface of the driven gear 3 at the tooth edge portion (near the point a in the figure) of the tooth surface of the drive side gear 12 existing at the terminal portion of the meshing action line B, It can be seen that the tooth edge portion of the tooth surface of the drive-side gear 12 and the tooth surface of the driven-side gear 3 are difficult to contact.

  As shown in FIG. 2, the reciprocating engine 10 of this example is an in-line four-cylinder reciprocating engine 10, and when the two pistons 13 are located at the top dead center U, the remaining two pistons 13 are at the bottom dead center L. It is comprised so that it may be located in. Each piston 13 is connected to a crank arm 111 provided on the crankshaft 11 via a connecting rod 14. Further, a counterweight 112 is formed on the crank arm 111 on the side opposite to the side where the connecting rod 14 is connected.

As shown in FIG. 1, the balance shaft mechanism 1 is attached to the engine by engaging the driven gear 3 with the drive gear 12 and screwing the housing 2 into the cylinder block 5 of the engine.
The drive-side gear 12 and the driven-side gear 3 of this example are provided at positions corresponding to the crankshaft 11 between the piston 13 positioned on the outermost side of the four pistons 13 and the piston 13 positioned on the inner side thereof. is there.

  Further, the reference pitch circle diameter and the number of teeth of the driven gear 3 are half of the reference pitch circle diameter and the number of teeth of the drive side gear 12. The gears 41 of the pair of balance shafts 4 have the same reference pitch circle diameter and the same number of teeth. When the crankshaft 11 rotates once, the driven gear 3 and the gear 41 of the pair of balance shafts 4 rotate twice.

As shown in FIG. 1, the balance weight 42 applies a balance force in a direction away from the piston 13 when each piston 13 connected to the crankshaft 11 is at the top dead center U or the bottom dead center L. It is configured.
That is, in this example, as shown in FIG. 2, the first and fourth pistons 13A and D located at both ends of the four cylinders are at the top dead center U, and the remaining second and third pistons 13B and C are at the bottom. When at the dead point L, the balance weight 42 generates a balance force in a direction away from each piston 13. Although not shown, when the first and fourth pistons 13A and 13D are at the bottom dead center L and the second and third pistons 13B and C are at the top dead center U, the balance weight 42 is A balance force is generated in a direction away from each piston 13A-D.

On the other hand, as shown in FIG. 3, when the first to fourth pistons 13 </ b> A to 13 </ b> D are at an intermediate position M between the top dead center U and the bottom dead center L, the balance weight 42 is in a direction approaching each piston 13 </ b> A to D. Generate balance force. Further, when the pair of balance shafts 4 are rotated in opposite directions, the pair of balance weights 42 forms a positional relationship that is closest to each other and a positional relationship that is most distant from each other.
In this way, the balance force (inertial force) by the balance weight 42 is applied in the direction opposite to the direction of action of the inertia force and the inertia couple generated by the reciprocating motion of the pistons 13A to 13D and the connecting rod 14, and the reciprocating engine 10 Generation of secondary vibration can be reduced.

  In the meshing structure of the pair of gears of this example, the pressure angle α1 of the drive side gear 12 provided on the crankshaft 11 is made larger than the pressure angle α2 of the driven side gear 3 provided on one balance shaft 4A. Yes. Thereby, even when the input torque by the output of the engine is applied to the drive side gear 12, only the tooth tip portion of the tooth surface of the drive side gear 12 is locally applied to the tooth bottom portion of the tooth surface of the driven side gear 3. Can be alleviated (see FIG. 5). Therefore, the wear of the resin tooth surface in the driven gear 3 of the one balance shaft 4A can be reduced.

  Further, as described above, the drive side gear 41A provided on one balance shaft 4A is made of metal, and the tooth surface of the driven side gear 41B provided on the other balance shaft 4B is made of resin. As in the relationship between the crankshaft 11 and one balance shaft 4A, the pressure angle of the drive side gear 41A in one balance shaft 4A is larger than the pressure angle of the driven side gear 41B in the other balance shaft 4B. You can also

  As a result, even when input torque due to engine output is applied to the drive side gear 41A in one balance shaft 4A, only the tooth tip portion of the tooth surface of the drive side gear 41A is driven side gear 41B in the other balance shaft 4B. It is possible to relieve local strong contact with the root part of the tooth surface. Therefore, the wear of the resin tooth surface in the driven gear 41B of the other balance shaft 4B can be reduced.

  Therefore, according to the meshing structure of the pair of gears in the balance shaft mechanism 1 of this example, it is possible to improve the durability reliability of the driven side gears 3 and 41B provided with resin tooth surfaces.

Explanatory drawing which shows the balance shaft mechanism in the Example seen from the axial direction of the crankshaft. Explanatory drawing which shows the balance shaft mechanism attached to the reciprocating engine in the Example seen from the side of the crankshaft. Explanatory drawing which shows the balance shaft mechanism attached to the reciprocating engine in the Example seen from the side of the crankshaft. Explanatory drawing which shows the cross section of the state which looked at the balance shaft mechanism in the Example from the direction of the crankshaft. The explanatory view which shows the state which the drive side gear of a crankshaft and the driven side gear of one balance shaft mesh in an Example. The explanatory view which shows the state which the drive side gear of a crankshaft and the driven side gear of one balance shaft mesh in an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Balance shaft mechanism 10 Reciprocating engine 11 Crankshaft 12 Drive side gear 2 Housing 3 Driven side gear 4 Balance shaft 41 Gear 42 Balance weight α1, α2 Pressure angle

Claims (4)

In a meshing structure of a metal drive side gear provided on a crankshaft of a reciprocating engine and a driven gear for rotating a pair of balance shafts, which has a resin tooth surface meshing with the drive side gear ,
A meshing structure of a pair of gears in a balance shaft mechanism, wherein a pressure angle of the drive side gear is larger than a pressure angle of the driven side gear. It has a metal drive-side gear on one balance shaft that is driven and rotated by the rotation of the crankshaft of the reciprocating engine, and a resin tooth surface that meshes with the drive-side gear, and the other balance shaft is driven and rotated. In the meshing structure with the driven side gear for
A meshing structure of a pair of gears in a balance shaft mechanism, wherein a pressure angle of the drive side gear is larger than a pressure angle of the driven side gear. In Claim 1 or 2, the driven gear is a standard gear having a pressure angle of 20 °,
The drive-side gear includes a gear having a pressure angle larger than that of the standard gear, and a meshing structure of a pair of gears in a balance shaft mechanism. The drive side gear according to claim 1 or 2, comprising a standard gear having a pressure angle of 20 °.
The driven gear includes a gear having a pressure angle smaller than that of the standard gear, and a meshing structure of a pair of gears in a balance shaft mechanism.

Images