JP5033677B2 - Gear meshing structure in power transmission mechanism - Google Patents

Description

  The present invention relates to a meshing structure of a drive gear and a driven gear in a power transmission mechanism.

In a power transmission mechanism such as a balancer mechanism used in a reciprocating engine, one of the gears to be driven is made of metal, and for the purpose of reducing gear noise (noise caused by gear meshing), the other gear to be driven is driven. The tooth surface is made of resin.
Further, for example, in the gear mechanism of the power transmission system of Patent Document 1, a second gear having a resin tooth surface meshes with a metal first gear, and a damping provided in the second gear. The mechanism suppresses the occurrence of a resonance phenomenon associated with gear meshing.

  Further, Patent Document 1 discloses a configuration in which a stopper rubber is provided in a counter gear provided on a balance shaft, and a protrusion is caused to collide with a circumferential end surface of the stopper rubber. And the volume of the acceleration side elastic part located in the circumferential direction one side in a stopper rubber is made larger than the volume of the deceleration side elastic part located in the circumferential direction other side. Thereby, the acceleration side elastic part to which a big load is applied compared with the deceleration side elastic part can be protected, and the durability of the stopper rubber is improved.

  However, Patent Document 1 is not sufficient to protect the stopper rubber from damage and the like more effectively. That is, in order to more effectively protect the stopper rubber from damage or the like, further contrivance is required for the shape of the stopper rubber.

JP 2001-193794 A

  The present invention has been made in view of such a conventional problem, and more effectively protects an acceleration-side elastic deformation portion to which a large collision force is applied from damage without increasing the volume of the stopper rubber as a whole. It is an object of the present invention to provide a gear meshing structure in a power transmission mechanism capable of achieving the above.

The present invention relates to a meshing structure of a metal drive gear provided on the first shaft portion and a driven gear provided on the second shaft portion in a state of being meshed with the drive gear provided with a resin tooth surface. ,
The first shaft portion and the second shaft portion are a crankshaft and a balance shaft that rotates following the rotation of the crankshaft in a reciprocating engine, or a driven shaft that receives the rotation of the crankshaft. A first balance shaft that rotates, and a second balance shaft that rotates following the rotation of the first balance shaft,
A disk-shaped rotating member is fixed to the second shaft portion,
Within the rotating member, stopper rubber is provided at equal intervals in a plurality of locations in the circumferential direction,
Between the stopper rubbers, a collision projection formed to project from the axial end surface of the driven gear is arranged in a state where a space is formed in the circumferential direction,
The stopper rubber is supported by a support portion that protrudes in the axial direction in the rotating member, and elastic deformation portions are arranged on both sides in the circumferential direction of the support portion, respectively.
The pair of elastically deforming portions are configured to be elastically deformed by being sandwiched between the collision projecting portion and the support portion, and the collision of the driven gear when the driven gear is accelerated by the rotation of the drive gear. An acceleration-side elastic deformation portion located on the side where the projection portion collides, and a deceleration-side elastic deformation portion located on the side where the collision projection portion collides when the driven gear decelerates due to the rotation of the drive gear. ,
The circumferential length of the portion of the acceleration side elastic deformation portion sandwiched between the collision projection portion and the support portion is sandwiched between the collision projection portion and the support portion of the deceleration side elastic deformation portion. 2 to 5 times the circumferential length of the part,
The radial length of the outer circumferential end surface with which the collision projection portion collides in the acceleration-side elastic deformation portion is longer than the radial length of the circumferential outer end surface with which the collision projection portion collides with the deceleration-side elastic deformation portion. In the gear meshing structure in the power transmission mechanism characterized in that (claim 1).

The gear meshing structure in the power transmission mechanism of the present invention is devised in the shape of the acceleration-side elastic deformation portion and the deceleration-side elastic deformation portion constituting the stopper rubber.
Specifically, the circumferential length of the acceleration-side elastic deformation portion is set to 2 to 5 times the circumferential length of the deceleration-side elastic deformation portion. Further, the radial length of the circumferential outer end surface of the acceleration side elastic deformation portion is set longer than the radial length of the circumferential outer end surface of the deceleration side elastic deformation portion.

Thereby, the volume of the acceleration side elastic deformation part can be more effectively made larger than the volume of the deceleration side elastic deformation part. The acceleration of the driven gear corresponds to the fact that the force that the collision projection collides with the acceleration side elastic deformation part during acceleration of the driven gear is larger than the force that the collision projection part collides with the deceleration side elastic deformation part during deceleration of the driven gear. Sometimes, the collision projection can collide with a large volume acceleration-side elastic deformation portion to secure a large amount of elastic deformation, whereas when the driven gear is decelerated, the collision projection portion has a small volume reduction-side elasticity. The amount of elastic deformation can be reduced by colliding with the deformable portion.
Therefore, the acceleration side elastic deformation part to which a big collision force is added can be more effectively protected from damage or the like.

Moreover, while increasing the volume of the acceleration side elastic deformation part, while reducing the volume of the deceleration side elastic deformation part, it can prevent that the volume as the whole stopper rubber increases.
Therefore, according to the gear meshing structure in the power transmission mechanism of the present invention, the elastic deformation portion on the acceleration side to which a large collision force is applied is more effectively protected from damage without increasing the volume of the stopper rubber as a whole. can do.

A preferred embodiment of the present invention described above will be described.
In the present invention, a circumferential length of a portion of the acceleration side elastic deformation portion sandwiched between the collision projection portion and the support portion is defined as a distance between the collision projection portion and the support portion in the deceleration side elastic deformation portion. If it is less than twice the circumferential length of the portion sandwiched between them, the volume of the acceleration-side elastic deformation portion cannot be increased sufficiently, and the acceleration-side elastic deformation portion cannot be sufficiently protected from damage or the like.
On the other hand, the circumferential length of the portion sandwiched between the collision projection and the support portion in the acceleration side elastic deformation portion is between the collision projection portion and the support portion in the deceleration side elastic deformation portion. If it exceeds 5 times the circumferential length of the sandwiched portion, the volume of the deceleration side elastic deformation portion becomes too small, and the rigidity required for the deceleration side elastic deformation portion cannot be maintained.
Further, the radial length of the outer circumferential end surface with which the collision projection portion collides with the acceleration elastic deformation portion is the radial length of the outer circumferential end surface with which the collision projection portion collides with the deceleration side elastic deformation portion. In the case of the following, it is difficult to sufficiently increase the volume of the acceleration side elastic deformation portion.

The first shaft portion may be a crankshaft in a reciprocating engine, and the second shaft portion may be a balance shaft that rotates following the rotation of the crankshaft .
In this case, the stopper rubber can be protected from damage or the like when the drive gear on the crankshaft is engaged with the driven gear on the balance shaft.

In addition, the first shaft portion is a first balance shaft that rotates following the rotation of the crankshaft in the reciprocating engine, and the second shaft portion is driven by the rotation of the first balance shaft. It can also be a rotating second balance shaft .
In this case, the stopper rubber can be protected from damage or the like in meshing between the gear in the first balance shaft and the gear in the second balance shaft.

Hereinafter, embodiments of the gear meshing structure in the power transmission mechanism of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 and 2, the gear meshing structure in the power transmission mechanism 1 of this example is a crankshaft 11 as a first shaft portion in order to reduce gear noise generated when the gears mesh. The balance shaft 4 serving as the second shaft portion is provided with a drive gear 12 made of metal (made of iron material) and a tooth surface made of resin (made of resin material). The present invention relates to a meshing structure with the provided driven gear 3.

  As shown in FIGS. 4 and 5, a disk-shaped rotating member 5 is fixed to the balance shaft 4, and stopper rubbers 6 are provided at equal intervals in the circumferential direction C in the rotating member 5. is there. Between the stopper rubbers 6, a collision protrusion 31 that protrudes from the axial end surface of the driven gear 3 is disposed in a state where a space 55 is formed in the circumferential direction C. The stopper rubber 6 is supported by support portions 53 that are formed so as to protrude in the axial direction in the rotating member 5, and elastic deformation portions 61 are disposed on both sides of the support portion 53 in the circumferential direction C.

  As shown in FIG. 5, the pair of elastic deformation portions 61 are configured to be elastically deformed by being sandwiched between the collision projection portion 31 and the support portion 53, and the driven gear 3 is received by the rotation of the drive gear 12. The acceleration side elastic deformation part 61A located on the side where the collision projection 31 collides when accelerating, and the deceleration located on the side where the collision projection 31 collides when the driven gear 3 decelerates due to the rotation of the drive gear 12 It consists of the side elastic deformation part 61B.

Further, as shown in FIG. 6, the circumferential length C1 of the portion sandwiched between the collision projection 31 and the support 53 in the acceleration-side elastic deformation 61A is equal to the collision projection 31 in the deceleration-side elastic deformation 61B. It is 2 to 5 times the circumferential length C2 of the portion sandwiched between the support portion 53. In addition, the radial length R1 of the outer circumferential end surface 611 with which the collision projection 31 collides in the acceleration-side elastic deformation portion 61A is equal to the diameter of the outer circumferential end surface 611 with which the collision projection 31 collides in the deceleration-side elastic deformation portion 61B. It is longer than the direction length R2.
5 and 6, the circumferential direction is indicated by an arrow C, and the radial direction is indicated by an arrow R.

Hereinafter, the gear meshing structure in the power transmission mechanism 1 of this example will be described in detail with reference to FIGS.
As shown in FIGS. 1 and 4, the power transmission mechanism 1 that employs the gear meshing structure of this example is a balance shaft mechanism 1 that is used to reduce the generation of primary and secondary vibrations of a reciprocating engine. The balance shaft mechanism 1 is configured to rotatably support a pair of balance shafts 4 that rotate following the rotation of a crankshaft 11 of a reciprocating engine on a 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.
In order to reduce gear noise, the gear 41 provided on one balance shaft 4 provided with the driven gear 3 is made of metal, and the gear 41 provided on the other balance shaft 4 is made of resin.

As shown in FIGS. 1 and 2, the first shaft portion of the present example is a crankshaft 11 in a reciprocating engine, and the second shaft portion of the present example is rotated following the rotation of the crankshaft 11. This is the balance shaft 4. The drive gear 12 of this example is provided on the crankshaft 11, and the driven gear 3 of this example is provided on one balance shaft 4.
As shown in FIGS. 4 and 5, the drive gear 12 and the driven gear 3 and the pair of gears 41 in this example are constituted by helical gears. The driven gear 3 is entirely made of resin, and a collision projection 31 that can collide with the elastic deformation portion 61 of the stopper rubber 6 is formed on the end face in the axial direction. The driven gear 3 can also be formed by fitting or coupling a resin outer peripheral part having a tooth surface to a metal inner peripheral part. The driven gear 3 is provided on one balance shaft 4 via a friction damper 32 that performs friction damping.

  As shown in FIG. 4, the rotating member 5 of this example is fixed at one end of the balance shaft 4 adjacent to the driven gear 3 and accommodates the stopper rubber 6 inside, that is, the axial direction of the stopper rubber 6. It has the bottom part 51 which faces an end surface, and the standing part 52 which stood up from the perimeter of the bottom part 51 so that the outer peripheral surface of the stopper rubber 6 may be faced. A support portion 53 for supporting the stopper rubber 6 is formed on the inner peripheral side of the rotating member 5.

  As shown in FIG. 5, the stopper rubber 6 of the present example is formed by connecting a pair of elastically deforming portions 61 by connecting portions 62, and a plurality of the stopper rubbers 6 at regular intervals in the circumferential direction C with respect to the rotating member 5 In the example, 4) are arranged. The stopper rubber 6 may be formed by integrally forming elastic deformation portions 61 at a plurality of locations in the circumferential direction C at an equal interval with respect to the annular base portion.

In addition, the plurality of pairs of elastic deformation portions 61 in the stopper rubber 6 includes an acceleration-side elastic deformation portion 61 </ b> A on one side in the circumferential direction C of the rotating member 5 and a deceleration side on the other side in the circumferential direction C of the rotating member 5. The elastic deformation part 61B is arranged.
The support portion 53 in the rotating member 5 of this example is formed from the inner peripheral surface of the standing portion 52 (formed at a position on the outer peripheral side of the rotating member 5), and the stopper rubber 6 is a pair of elastic members. The outer peripheral side portion between the deforming portions 61 is cut out, and the inner peripheral side portion is connected by a connecting portion 62.
In addition, the formation position of the support part 53 was changed, and as shown in FIG. 7, the stopper rubber 6 cuts out the inner peripheral part between the pair of elastic deformation parts 61, and connects the outer peripheral part. It can also be formed.

As shown in FIGS. 2 and 3, the reciprocating engine of this example is an in-line 4-cylinder reciprocating engine, and when the two pistons 13 are located at the top dead center U, the remaining two pistons 13 are at bottom dead center. It is comprised so that it may be located in L. 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 with the cylinder block 5 of the engine.
The drive gear 12 and the driven 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.

  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 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 the 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 1 Generation of secondary vibration can be reduced.

Next, the operation of the reciprocating engine and the balance shaft mechanism (power transmission mechanism) 1 will be described.
When the reciprocating engine accelerates, the rotational speed of the drive gear 12 provided on the crankshaft 11 increases, and the driven gear 3 meshing with the drive gear 12 is driven to rotate. At this time, the driven gear 3 rotates idly while being attenuated by the friction damper 32 until the collision protrusion 31 collides with the acceleration-side elastic deformation portion 61 </ b> A of the stopper rubber 6 accommodated in the rotating member 5. Then, in a state where the collision projection 31 collides with the acceleration-side elastic deformation portion 61 </ b> A, one balance shaft 4 is rotated by the driven gear 3, and the other balance shaft 4 is driven and rotated via the pair of gears 41.

  On the other hand, when the reciprocating engine decelerates, the rotational speed of the drive gear 12 provided on the crankshaft 11 and the rotational speed of the driven gear 3 meshing with the drive gear 12 decrease, while the pair of balance shafts 4 are caused by inertial force. Attempts to continue rotating at the rotational speed before deceleration. At this time, the pair of balance shafts 4 idle until the deceleration elastic deformation portion 61 </ b> B of the stopper rubber 6 accommodated in the rotating member 5 collides with the collision protrusion 31 of the driven gear 3. The rotational speed of the pair of balance shafts 4 is reduced in a state in which the deceleration-side elastic deformation portion 61B collides with the collision projection portion 31, and then the pair of balance shafts 4 is rotated according to the rotation of the drive gear 12 and the driven gear 3. Rotate.

As described above, in the stopper rubber 6, the circumferential length C1 of the acceleration side elastic deformation portion 61A is set to 2 to 5 times the circumferential length C2 of the deceleration side elastic deformation portion 61B. The radial length R1 of the circumferential outer end surface 611 of the acceleration side elastic deformation portion 61A is set longer than the radial length R2 of the circumferential outer end surface 611 of the deceleration side elastic deformation portion 61B.
Thereby, the volume of the acceleration side elastic deformation part 61A can be more effectively made larger than the volume of the deceleration side elastic deformation part 61B. The force that the collision projection 31 collides with the acceleration-side elastic deformation portion 61A when the driven gear 3 is accelerated corresponds to the force that the collision projection 31 collides with the deceleration-side elastic deformation portion 61B when the driven gear 3 decelerates. When the driven gear 3 is accelerated, the collision projection 31 can collide with the large-volume acceleration-side elastic deforming portion 61A to secure a large amount of elastic deformation, whereas when the driven gear 3 is decelerated, The collision projection 31 can collide with the deceleration-side elastic deformation portion 61B having a small volume, and the elastic deformation amount can be reduced.
Therefore, it is possible to more effectively protect the acceleration side elastic deformation portion 61A to which a large collision force is applied from damage or the like.

Moreover, while increasing the volume of the acceleration side elastic deformation part 61A, decreasing the volume of the deceleration side elastic deformation part 61B can prevent the volume of the stopper rubber 6 as a whole from increasing. .
Therefore, according to the gear meshing structure in the power transmission mechanism 1 of this example, the acceleration-side elastic deformation portion 61A to which a large collision force is applied is more effective from damage without increasing the volume of the stopper rubber 6 as a whole. Can be protected.

Explanatory drawing which shows the power transmission mechanism in the Example seen from the axial direction of the crankshaft. Explanatory drawing which shows the power transmission mechanism attached to the reciprocating engine in the Example seen from the side of the crankshaft. Explanatory drawing which shows the power transmission 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 power transmission mechanism in the Example from the direction of the crankshaft. Explanatory drawing which shows the state which has arrange | positioned the stopper rubber in the rotation member in an Example in the cross section of the state seen from the axial direction of the balance shaft. Explanatory drawing which shows the stopper rubber | gum in an Example. Explanatory drawing which shows the other stopper rubber in an Example.

Explanation of symbols

1 Balance shaft mechanism (power transmission mechanism)
11 Crankshaft (first shaft)
12 Drive gear 2 Housing 3 Driven gear 31 Collision projection 4 Balance shaft (second shaft)
41 Gear 42 Balance weight 43 Shaft part 5 Rotating member 53 Support part 55 Space 6 Stopper rubber 61A Acceleration side elastic deformation part 61B Deceleration side elastic deformation part

Claims (1)

In a meshing structure with a driven gear provided on the second shaft portion in a state of meshing with the drive gear provided with a metal drive gear provided on the first shaft portion and a resin tooth surface,
The first shaft portion and the second shaft portion are a crankshaft and a balance shaft that rotates following the rotation of the crankshaft in a reciprocating engine, or a driven shaft that receives the rotation of the crankshaft. A first balance shaft that rotates, and a second balance shaft that rotates following the rotation of the first balance shaft,
A disk-shaped rotating member is fixed to the second shaft portion,
Within the rotating member, stopper rubber is provided at equal intervals in a plurality of locations in the circumferential direction,
Between the stopper rubbers, a collision projection formed to project from the axial end surface of the driven gear is arranged in a state where a space is formed in the circumferential direction,
The stopper rubber is supported by a support portion that protrudes in the axial direction in the rotating member, and elastic deformation portions are arranged on both sides in the circumferential direction of the support portion, respectively.
The pair of elastically deforming portions are configured to be elastically deformed by being sandwiched between the collision projecting portion and the support portion, and the collision of the driven gear when the driven gear is accelerated by the rotation of the drive gear. An acceleration-side elastic deformation portion located on the side where the projection portion collides, and a deceleration-side elastic deformation portion located on the side where the collision projection portion collides when the driven gear decelerates due to the rotation of the drive gear. ,
The circumferential length of the portion of the acceleration side elastic deformation portion sandwiched between the collision projection portion and the support portion is sandwiched between the collision projection portion and the support portion of the deceleration side elastic deformation portion. 2 to 5 times the circumferential length of the part,
The radial length of the outer circumferential end surface with which the collision projection portion collides in the acceleration-side elastic deformation portion is longer than the radial length of the circumferential outer end surface with which the collision projection portion collides with the deceleration-side elastic deformation portion. A gear meshing structure in a power transmission mechanism.

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