JP2011179565A - Gear device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gear device that reduces misalignment between gears by allowing elastic deformation of a gear in a gear warpage direction, while increasing stiffness of the gear in a radial direction. <P>SOLUTION: In the gear device 1, a rim 10 is integrally formed through a hub 11 on an outer peripheral side of a boss 9 fitted to a shaft 4. The device includes gears 5, wherein gear teeth are formed in an outer peripheral surface of the rim 10. As driving power is transmitted by engaging the gears 5 with each other, a warpage is caused in the shaft 4 fitted to the gears 5. An elastic part 11 allowing a relative warpage between the gear teeth and the shaft 4 on the occurrence of warpage in the shaft 4 and a reinforcement member 12 provided in a sidewall surface of the elastic part 11 for increasing the stiffness of the gear 5 in the a radial direction, are provided in at least either the boss 9 or the hub 11. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a gear device, and more particularly to a gear device that is elastically deformed by a load that the gear receives during power transmission.

  When transmitting the power, the gear device transmits the power in the direction in which the driven gear is rotated and may apply a load in a direction different from the rotation direction of the driven gear. In particular, in the case of a helical gear, a load (thrust load) in a direction perpendicular to the rotation direction of the driven gear, that is, a rotation axis direction and a load in the radial direction of the gear (radial load) are generated.

  In Patent Document 1, when the shaft of the driving gear and the shaft of the driven gear are not parallel, a bevel gear is usually provided. However, since it is difficult to form a bevel gear, the spur gear is elastic in the direction in which it warps. A gear device having a configuration in which the plate thickness of a part of the intermediate portion in the radial direction of the gear is thinned so as to be deformable is described.

JP 2000-249213 A

  The gear device described in Patent Literature 1 can reduce the thickness of a part of the intermediate portion in the radial direction of the gear so that the gear can be warped. The shaft of the driving side gear and the shaft of the driven side gear The spur gears can mesh even when are not parallel. However, meshing a spur gear that is elastic in the warping direction with non-parallel shafts differs in the distance from the rotating shaft on one end side and the other end side in the axial direction of the gear. That is, since the speeds at the ends of the different end side and the other end side in the axial direction of the gear are different, there is a possibility that the meshing loss due to misalignment increases. Further, the device described in Patent Document 1 is made of resin, and is used, for example, in a place where a large transmission load acts, that is, in a place where a radial load of the gear is large, like a power transmission device in a vehicle. In this case, since the rigidity in the radial direction is low, there is a possibility that tooth skipping may occur, and it cannot be applied. Therefore, there is still room for improvement with respect to the gear device that is provided at a location where the transmission load is large and can maintain the meshing state even when the rotation shaft is inclined.

  The present invention has been made by paying attention to the above-mentioned problem, and is a gear that can be elastically deformed in the direction in which the gear warps and can reduce misalignment between the gears by increasing the rigidity in the radial direction. An object is to provide an apparatus.

  In order to achieve the above object, according to the first aspect of the present invention, a rim portion is integrally formed on the outer peripheral side of a boss portion fitted to a shaft via a hub portion, and teeth are formed on the outer peripheral surface of the rim portion. In the gear device in which the shaft that is engaged with the gear is deflected by transmitting the power by meshing the gears with each other, the boss portion and the hub portion are provided. At least one of the elastic portion that allows a relative curvature between the teeth and the shaft when the shaft is bent, and the rigidity of the gear in the radial direction provided on the side wall surface of the elastic portion. And a reinforcing member for increasing the thickness.

  According to a second aspect of the present invention, in the first aspect of the invention, the elastic portion is formed by reducing a plate thickness of at least one of the hub portion and the boss portion, and the reinforcing member is the hub portion. The gear device is characterized by being fitted into the entire portion where the plate thickness is reduced.

  According to a third aspect of the present invention, in the first aspect of the invention, the elastic portion is formed by reducing a plate thickness of at least one of the hub portion and the boss portion, and the reinforcing member is the hub portion. The gear device is provided with a certain interval in the circumferential direction.

  According to the present invention, the elastic part is provided in at least one of the boss part fitted to the shaft and the hub part provided on the outer peripheral side of the boss part. Even when the shaft is bent by a load, the gear can be warped and the meshing state of the gear can be maintained. In addition, since the reinforcing member for increasing the radial rigidity of the gear is provided on the side wall surface of the elastic part, the radial rigidity of the gear is increased, so even when the gear receives a radial load, Can be controlled. Therefore, the meshing loss due to gear misalignment can be reduced.

It is sectional drawing which shows an example of the gear apparatus which concerns on this invention. It is the schematic which shows an example of the gear train in the gear apparatus which concerns on this invention. It is a schematic diagram which shows the force which acts on a 2nd shaft. It is the schematic which shows the state which the 2nd gear inclined according to the inclination of a 2nd shaft. It is the schematic which shows the state which the 2nd gear is absorbing the inclination of a 2nd shaft. It is sectional drawing which shows the shape of a 2nd gear. It is a top view which shows the other structure of the gear apparatus which concerns on this invention.

  Next, a gear device according to the present invention will be described. FIG. 2 schematically shows a gear train of a gear device 1 in a vehicle, and includes a first gear 3 fitted to a first shaft 2 connected to a power source (not shown), A second gear 5 fitted to a second shaft 4 provided in parallel with the shaft 2 meshes with it to transmit power. Further, a third gear 6 fitted to the second shaft 4 and provided on the left side of the second gear 5 in the drawing and a third shaft 7 provided in parallel to the second shaft 4 are provided. The fitted fourth gear 8 meshes to transmit power. And the 3rd shaft 7 is connected with the wheel via the axle shaft etc. which are not illustrated.

In the gear train of the gear device 1 configured as described above, particularly when each of the gears 3, 5, 6, and 8 is a helical gear, so-called separation in which the gears that are engaged with each other exert a force in the direction of separating them from each other. The gears 3, 5, 6, 8 receive the force in the radial direction. Accordingly, the shafts 2, 4, 7 fitted to the gears 3, 5, 6, 8 receive a force in the vertical direction in the figure. FIG. 3 schematically shows the force received by the second shaft 4, and the force W ₂ is applied upward to the second shaft 4 by power transmission between the first gear 3 and the second gear 5. Acts, and the force W ₁ acts downward by the power transmission between the third gear 6 and the fourth gear 8. Note that the maximum values of the force W ₁ acting downward and the force W ₂ acting upward can be determined by predetermining the maximum torque to be applied to the gears 3, 5, 6, 8. Then, by the force W ₁ acting downward on the second shaft 4, the following equation deflection amount between the working point B of the force W ₁ acting on the left support portion A and the lower direction of the second shaft 4 In (1), the amount of deflection between the point of action B and the right support portion D of the second shaft 4 can be obtained by the following equation (2).

In the equations (1) and (2), y ′ represents the state in which the second shaft 4 is not bent, that is, the amount of deflection based on the design value, a is the distance between the left support A and the action point B, b is the distance between the point C of the force W ₂ acting upward to the point B and the second shaft 4, c is the distance between the action point C and the right support portion D, E is Young's modulus, I is the elastic A secondary moment, l represents the total length of the second shaft 4, and x represents an arbitrary distance from the left support A.

Further, due to the force W ₂ acting upward on the second shaft 4, the deflection amount between the left support portion A and the action point C is expressed by the following equation (3), and the action point C and the right support portion D: The amount of deflection between the two can be obtained by the following equation (4).

  Note that y ″ in the equations (3) and (4) indicates a state in which the second shaft 4 is not bent, that is, a deflection amount with reference to a design value.

  Furthermore, the amount of deflection between the left support portion A and the right support portion D due to the respective moments acting on the fixed end A and the fixed end D can be obtained by the following equation (5).

In y '''in Formula (5) shows the bending amount of the basis of the absence state or the design value deflection of the second shaft 4, the M _A and M _B the following equation (6) and (7) is there.

Incidentally, M _A represents a moment acting on the left support section A, M _B represents the moment acting on the right support portion D. By summing up the above equations, the amount of deflection due to the resultant force generated in the second shaft 4 can be obtained.

Therefore, the amount of deflection at an arbitrary position of the second shaft 4 can be obtained, so that the second gear when the second gear 5 is inclined according to the inclination of the second shaft 4 as shown in FIG. By substituting the _two end coordinates x ₁ and x ₂ in the axial direction of 5 into the above equation (5), the height difference in the radial direction of the second shaft can be obtained. Since the amount of bending of the second shaft 4 is very small, the coordinates of both ends of the second gear 5 when the second shaft 4 is not bent are approximated as x ₁ and x ₂ . That is, by substituting the following formulas (9) and (10) into the above formula (5), the deflection amounts y ₁ and y ₂ in the radial direction of the shaft 4 at each location can be obtained.

Then, the absolute value of the difference between y ₁ and y ₂ obtained by substituting x ₁ and x ₂ obtained by the equations (9) and (10) into the equation (5), that is, the height difference is the second value. The value obtained by dividing the upward force W ₂ acting on the shaft 4 is the amount by which the second shaft 4 bends due to the resultant force W ₁ , W ₂ acting on the second shaft 4 and the moment of the fixed end. This is the spring constant required for absorption. Formula (11) for obtaining the spring constant is shown below.

  As a result of the above calculation, the spring constant required to absorb the deflection of the second shaft 4 can be obtained, and the shape that allows the second gear 5 to be elastically deformed can be determined in accordance with the spring constant. .

  That is, as shown in FIG. 6, by reducing the plate thickness of the hub portion 11 located between the rim portion 10 where the teeth are formed and the boss portion 9 fixed to the shaft, the direction of the gear warping is reduced. The plate thickness may be formed to match the spring constant. A state where the second gear 5 absorbs the inclination of the second shaft 4 is shown in FIG.

  With this configuration, the gear can absorb the inclination of the shaft. Further, since both end portions of the shaft are fixed ends, the shaft does not move in the vertical direction in the figure, and the rotation axis of the shaft does not change. That is, the rotation axis and the tooth trace can be maintained in a parallel state.

  Further, the gear according to the present invention suppresses bending of the gear in the radial direction when the transmission force is large, that is, when the load in the radial direction of the gear is large. By providing the reinforcing member 12, the rigidity in the radial direction is increased. FIG. 1 shows an example in which the reinforcing member 12 is provided. An annular reinforcing member 12 is attached to the side wall surface of the portion where the plate thickness is reduced by shrink fitting. The material of the reinforcing member 12 is preferably a material having higher rigidity than the gear material. For example, it is preferable that the gear material is alloy steel (E = 200 GPa) and the reinforcing member 12 is cemented carbide (E = 440 to 550 GPa). Accordingly, the radial rigidity of the gear can be increased by the reinforcing member 12. Further, since the plate thickness including the plate thickness of the reinforcing member 12 of the hub portion 11 is thinner in the direction in which the gear is warped, the gear is more likely to warp than a conventional gear, that is, a gear with a uniform thickness, and the meshing state of the gear is a shaft. It is hard to be influenced by the inclination of In addition, although the reinforcement member 12 in a figure is provided in the both wall surfaces of the hub part 11, only a single wall surface may be sufficient.

  In the present invention, the thickness of a part of the gear is thinned to facilitate elastic deformation in the direction in which the gear is warped, and the reduction in the rigidity in the radial direction is compensated by the reinforcing member 12. It is not limited to examples. That is, the reinforcing member 12 may be ribs 13 provided at predetermined intervals in the circumferential direction from the boss portion 9 toward the rim portion 10 as shown in FIG.

  DESCRIPTION OF SYMBOLS 1 ... Gear apparatus, 2, 4, 7 ... Shaft, 3, 5, 6, 8 ... Gear, 9 ... Boss part, 10 ... Rim part, 11 ... Hub part, 12 ... Reinforcement member, 13 ... Rib

Claims (3)

On the outer peripheral side of the boss part fitted to the shaft, a rim part is integrally formed through a hub part, and a gear having teeth formed on the outer peripheral surface of the rim part,
In the gear device in which the shaft engaged with the gear bends as the gears mesh with each other to transmit power,
An elastic part that allows a relative warp between the teeth and the shaft when the shaft is bent in at least one of the boss portion and the hub portion;
A gear device, comprising: a reinforcing member provided on a side wall surface of the elastic portion and increasing rigidity in a radial direction of the gear. The elastic part is formed by reducing the thickness of a part of at least one of the hub part and the boss part,
2. The gear device according to claim 1, wherein the reinforcing member is provided so as to be fitted into an entire portion where the thickness of the hub portion is reduced. The elastic part is formed by reducing the thickness of a part of at least one of the hub part and the boss part,
2. The gear device according to claim 1, wherein the reinforcing members are provided at a predetermined interval in a circumferential direction of the hub portion.

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