JP6599682B2 - Planetary gear set - Google Patents

Description

  The present invention relates to a planetary gear device having a helical gear.

  As a planetary gear device used in a power transmission mechanism of an aircraft or the like, one using a double helical gear as a planetary gear is known (see Patent Document 1). When the double helical gear is used, torque fluctuation is reduced by increasing the number of teeth meshed simultaneously, and the thrust force is canceled by the pair of helical gears arranged in parallel in the rotational axis direction.

International Publication No. 2011/129110

  By the way, when there is a strong demand for increasing the transmission torque per unit mass or unit volume of an planetary gear unit such as an aircraft, a method of simply increasing the transmission torque without changing the gear size, and reducing the diameter of each gear. For example, a method of thinning the rim of the ring gear meshing with the planetary gear can be considered. In particular, reducing the thickness of the rim also has the effect of reducing the rigidity and distributing the load between the planetary gears. In any method, the ratio of the transmission load to the rim thickness increases, and the stress generated in the rim increases.

  On the other hand, each of the inner teeth of the ring gear has tooth traces extending in a direction inclined with respect to the rotation axis direction of the ring gear, and therefore the contour viewed from the tooth tip side of the inner teeth is a parallelogram. Therefore, at one end portion in the tooth width direction orthogonal to the tooth thickness direction of the inner teeth, the end portion in the tooth width direction of each surface of the first tooth surface contacting the outer teeth of the planetary gear and the second tooth surface on the opposite side. The positions are shifted from each other. Therefore, the width of the first tooth surface becomes longer than the width of the second tooth surface at one end portion in the tooth width direction of the internal tooth, and the thickness becomes thinner and the rigidity decreases as the end portion approaches. Then, when the outer teeth of the planetary gear mesh with each other and the pressing force acts on the inner teeth of the ring gear, the inner teeth fall locally on the second tooth surface side due to the pressing force acting on the first tooth surface at one end portion of the inner teeth. Deformation tends to occur. Therefore, in consideration of local stress, there are limits to simple torque increase, gear diameter reduction, and ring gear rim thickness reduction. This is particularly important in applications where a thin-walled structure having a large transmission torque and reduced rigidity to reduce the weight is employed, such as an aircraft.

  Accordingly, an object of the present invention is to provide a planetary gear device having a helical gear and capable of suppressing local stress.

  A planetary gear device according to an aspect of the present invention includes a sun gear having external teeth, a plurality of planetary gears having external teeth and meshing with the sun gear, and a ring gear having internal teeth and meshing with the planetary gear, The ring gear is composed of at least one helical gear in which each of the inner teeth extends in a direction inclined with respect to the rotation axis direction of the ring gear, and each of the inner teeth of the ring gear includes the outer teeth of the planetary gear. And a second tooth surface opposite to the first tooth surface, and a pressure angle of the second tooth surface is larger than a pressure angle of the first tooth surface.

  According to the said structure, since a ring gear is comprised with a helical gear, the edge part position of the tooth width direction of each surface of a 1st tooth surface and a 2nd tooth surface mutually shifts, and tooth thickness becomes thin toward an edge part. Although there is a tendency, the pressure angle of the second tooth surface is set larger than the pressure angle of the first tooth surface. Therefore, when the external teeth of the planetary gear press the first tooth surface of the inner teeth of the ring gear, the portion on the second tooth surface side of the inner teeth can sufficiently obtain a rib effect that suppresses deformation due to the load. It is possible to prevent deformation in which the inner teeth fall to the second tooth surface side at one end in the width direction. Therefore, local stress generated in the ring gear can be suppressed.

  The ring gear may be a double helical gear, and the at least one helical gear may be a pair of helical gears arranged in parallel in the rotation axis direction.

  According to the above configuration, in the double helical gear, the number of one end portions in the tooth width direction in which the internal teeth are liable to fall down is doubled. Therefore, the deformation prevention by the rib effect of the second tooth surface side portion of the internal teeth described above. Becomes more effective.

  In the double helical gear, the inner teeth of the inner teeth are positioned on the first tooth surface side in the circumferential direction of the ring gear relative to the inner ends of the inner teeth in the tooth width direction. It may be inclined in the direction.

  According to the said structure, the edge part of the tooth width direction in which the deformation | transformation in which an internal tooth falls easily will be located in the both ends of the rotation axis direction of a double helical gear, respectively. Since both ends of the rim of the ring gear in the rotational axis direction are free ends, deformation is more likely to occur than in the central part in the rotational axis direction. In such a configuration, as described above, the rib effect of the portion of the internal tooth on the second tooth surface side can be obtained, which can further contribute to the prevention of deformation.

  Each of the external teeth of the planetary gear has a first tooth surface that contacts the internal teeth of the ring gear, and a second tooth surface that contacts the external teeth of the sun gear on the opposite side of the first tooth surface. Each of the external teeth of the sun gear has a first tooth surface and a second tooth surface that contacts the external teeth of the planetary gear on the opposite side of the first tooth surface, and the planetary gear and the sun gear The pressure angle of the second tooth surface may be larger than the pressure angle of the first tooth surface of the planetary gear and the sun gear, respectively.

  According to the above configuration, since the external teeth of the sun gear, which are engaged more often than the internal teeth of the ring gear, come into contact with the external teeth of the planetary gear at the second tooth surface having a large pressure angle, the tooth by reducing the surface pressure of the second tooth surface. The effect of suppressing surface fatigue and the effect of improving seizure resistance by reducing the sliding speed during meshing can be suitably exhibited.

  According to the present invention, it is possible to provide a planetary gear device having a helical gear and capable of suppressing local stress.

It is sectional drawing seen from the rotating shaft direction of the planetary gear apparatus which concerns on embodiment. It is a perspective view of the ring gear of the planetary gear apparatus of FIG. It is typical sectional drawing of the principal part of the planetary gear apparatus of FIG. It is drawing which looked at the internal tooth of the ring gear of FIG. 2 from the tooth tip side. FIG. 5 is a view corresponding to FIG. 4 in which the internal teeth of a ring gear of a modification are viewed from the tooth tip side.

  Hereinafter, embodiments will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view of the planetary gear device 1 according to the embodiment as viewed from the direction of the rotation axis X. The planetary gear device 1 of the present embodiment is used, for example, in a power transmission mechanism (deceleration mechanism) such as an aircraft engine. As shown in FIG. 1, the planetary gear device 1 includes a sun gear 3 that is fitted and fixed to the outer periphery of the input shaft 2, a plurality of (for example, five) planetary gears 4 that mesh with the sun gear 3, and a ring gear 5 that meshes with the planetary gear 4. With. The sun gear 3 has external teeth 6. The plurality of planetary gears 4 are arranged at equal intervals in the circumferential direction of the sun gear 3. Each planetary gear 4 has external teeth 7 and is rotatably supported on the outer periphery of the planetary shaft 8 via a bearing (not shown). The end of each planetary shaft 8 is attached to a planetary carrier (not shown), thereby determining the relative position between the planetary gears 4. The ring gear 5 has internal teeth 9. The ring gear 5 may be fixed to be non-rotatable and power may be output from the planetary carrier, the planetary carrier may be fixed to be non-rotatable and power may be output from the ring gear 5, or the ring gear 5 and the planetary carrier Power may be output from both. Further, the target to which power is input from the input shaft is not limited to the sun gear 3 but may be the planetary carrier or the ring gear 5.

  FIG. 2 is a perspective view of the ring gear 5 of the planetary gear device 1 of FIG. As shown in FIG. 2, the ring gear 5 is a double helical gear including a pair of helical gears 11 and 12 arranged in parallel in the rotation axis X direction. However, the ring gear 5 is not limited to a double helical gear, and a single helical gear may be used. The helical gears 11 and 12 have rims 13 and 14 and internal teeth 9. The rims 13 and 14 are cylindrical. A large number of inner teeth 9 protrude radially inward from the inner peripheral surfaces of the rims 13 and 14 respectively. The internal teeth 9 extend in a direction inclined with respect to the rotation axis X direction of the ring gear 5.

  The helical gears 11 and 12 further have flanges 15 and 16. However, the flanges 15 and 16 may be omitted. For example, the pair of helical gears 11 and 12 constituting the ring gear 5 may be integrated. The flanges 15 and 16 protrude outward in the radial direction from the outer periphery of the opposite ends of the rims 13 and 14. The pair of helical gears 11 and 12 form a double helical gear by the pair of flanges 15 and 16 being fixed to each other by fastening members (for example, bolts). The internal teeth 9 of the helical gear 11 and the internal teeth 9 of the helical gear 12 are inclined in opposite directions. An annular groove 17 is formed around the rotation axis X between the inner teeth 9 aligned in the rotation axis X direction on the inner peripheral surfaces of the opposite ends of the rims 13 and 14. The planetary gear 4 is a double helical gear corresponding to the ring gear 5, and the sun gear 3 is also a double helical gear corresponding to the planetary gear 4. Similarly, when the ring gear 5 is a single helical gear, the planetary gear 4 and the sun gear 3 are single helical.

  FIG. 3 is a schematic cross-sectional view of a main part of the planetary gear device 1 of FIG. In FIG. 3, for convenience of explanation, only some of the many teeth are illustrated, and the teeth are illustrated as enlarged. As shown in FIG. 3, each of the internal teeth 9 of the ring gear 5 includes a first tooth surface 9 a on one side in the circumferential direction of the ring gear 5, and the other side in the circumferential direction of the ring gear 5 (opposite side to the first tooth surface 9 a). It has the 2nd tooth surface 9b and the tooth-tip surface 9c which connects the 1st tooth surface 9a and the 2nd tooth surface 9b in the radial inside of the ring gear 5. The first tooth surface 9 a abuts on the external teeth 7 of the planetary gear 4 when the ring gear 5 meshes with the planetary gear 4. The first tooth surface 9a is a concave surface when viewed from the direction of the rotation axis X. In the normal use state in which the first tooth surface 9a is pressed by the external teeth 7 to transmit torque, the second tooth surface 9b does not contact any gear. The second tooth surface 9b is a convex surface when viewed from the direction of the rotation axis X, but may be a concave surface. The pressure angle of the second tooth surface 9b is larger than the pressure angle of the first tooth surface 9a. In other words, the tooth tip surface 9 c is located in the inner tooth 9 so as to be biased toward the first tooth surface 9 a side.

  Each of the external teeth 7 of the planetary gear 4 includes a first tooth surface 7a that contacts the internal teeth 9 of the ring gear 5, and a second tooth surface 7b on the other circumferential side of the planetary gear 4 (opposite side of the first tooth surface 7a). And a tooth tip surface 7c that connects the first tooth surface 7a and the second tooth surface 7b on the radially outer side of the planetary gear 4. The first tooth surface 7 a comes into contact with the first tooth surface 9 a of the inner tooth 9 of the ring gear 5 when the planetary gear 4 meshes with the ring gear 5. The second tooth surface 7 b comes into contact with the external teeth 6 of the sun gear 3 when the planetary gear 4 meshes with the sun gear 3. The first tooth surface 7a and the second tooth surface 7b are convex surfaces when viewed from the rotation axis X direction. The pressure angle of the second tooth surface 7b is larger than the pressure angle of the first tooth surface 7a. In other words, the tooth tip surface 7 c is located on the outer tooth 7 so as to be biased toward the first tooth surface 7 a.

  Each of the external teeth 6 of the sun gear 3 includes a first tooth surface 6a on one side in the circumferential direction of the sun gear 3, a second tooth surface 6b on the other circumferential side of the sun gear 3 (opposite side of the first tooth surface 6a), A tooth tip surface 6c that connects the first tooth surface 6a and the second tooth surface 6b on the radially outer side of the sun gear 3 is provided. The second tooth surface 6 b contacts the second tooth surface 7 b of the external tooth 7 of the planetary gear 4 when the sun gear 3 meshes with the planetary gear 4. In the normal use state in which the second tooth surface 6b is pressed by the external teeth 7 to transmit torque, the first tooth surface 6a does not contact any gear. The first tooth surface 6a and the second tooth surface 6b are convex surfaces when viewed from the rotation axis X direction. The pressure angle of the first tooth surface 6a is smaller than the pressure angle of the second tooth surface 6b. In other words, the tooth tip surface 6 c is located on the outer tooth 6 so as to be biased toward the first tooth surface 6 a.

  FIG. 4 is a view of the internal teeth 9 of the ring gear 5 of FIG. 2 as viewed from the tooth tip side. As shown in FIG. 4, each of the internal teeth 9 of the ring gear 5 extends in a direction inclined with respect to the rotation axis direction of the ring gear 5. Specifically, in the ring gear 5, the inner teeth 9 are arranged such that the outer end 9 d on the outer side in the rotation axis direction of the inner teeth 9 is more in the circumferential direction of the ring gear 5 than the inner end 9 e on the inner side in the rotation axis direction of the inner teeth 9. It inclines in the direction which is located in the 1 tooth surface 9a side. The contours of the inner teeth 9 viewed from the tooth tip side are parallelograms. That is, in the outer end portion 9d orthogonal to the tooth thickness direction of the inner tooth 9, the end position in the tooth width direction of each surface of the first tooth surface 9a and the second tooth surface 9b is shifted from each other, The outer end 9d of the tooth 9 has a triangular shape (hatched portion in FIG. 4) as viewed from the tooth tip side. For this reason, paying attention only to the outer end portion 9d of the inner tooth 9, the second tooth surface 9b tends to be shorter than the first tooth surface 9a, and the tooth thickness tends to become thinner toward the end portion.

  As shown in FIGS. 3 and 4, in the present embodiment, the pressure angle of the second tooth surface 9b is set larger than the pressure angle of the first tooth surface 9a. Therefore, when the internal teeth 9 are viewed from the tooth tip side, the length L2 of the second tooth surface 9b in the tooth thickness direction is longer than the length L1 of the first tooth surface 9a in the tooth thickness direction. Then, the region of the second tooth surface 9b in the outer end portion 9d is formed to be relatively large. Therefore, when a pressing force is applied from the outer teeth 7 of the planetary gear 4 to the first tooth surfaces 9a of the inner teeth 9 of the ring gear 5, the rib effect in which the portion of the inner teeth 9 on the second tooth surface 9b side suppresses deformation due to the load. The outer end 9d in the tooth width direction of the inner teeth 9 is prevented from being deformed to the second tooth surface 9b side. Therefore, local stress generated by the power transmitted from the inner teeth 9 to the rims 13 and 14 can be suppressed. As a result, the rims 13 and 14 of the ring gear 5 can be thinned. In addition, it is possible to prevent changes in the contact location between the internal teeth 9 and the planetary gear 4 due to the internal teeth 9 falling, and it is also possible to suppress local stress generated by the power transmitted from the planetary gear 4 to the internal teeth 9. Become.

  In addition, even in the external teeth 7 of the planetary gear 4, even if the pressing force acts on the first tooth surface 7 a by meshing with the ring gear 5, the rib effect on the second tooth surface 7 b side of the external teeth 7 suppresses deformation due to load. Is sufficiently obtained, and the deformation of the outer end portion of the external tooth 7 in the tooth width direction falling to the second tooth surface 7b side is prevented. Further, the outer teeth 6 of the sun gear 3 and the outer teeth 7 of the planetary gear 4 are in contact with the second tooth surfaces 6b and 7b. At this time, since the second tooth surfaces 6b and 7b form a high pressure angle, the surface pressure of the second tooth surfaces 6b and 7b is reduced, and tooth surface fatigue can be suppressed. Further, since the second tooth surfaces 6b and 7b form a high pressure angle, the sliding speed at the time of meshing is reduced, and seizure resistance is improved.

  FIG. 5 is a view corresponding to FIG. 4 in which the internal teeth 109 of the ring gear 105 of the modification are viewed from the tooth tip side. As shown in FIG. 5, in the ring gear 105 of this example, the inner teeth 109 are configured such that the outer end 109 d of the inner teeth 109 on the outer side in the rotation axis direction is closer to the ring gear 105 than the inner end 109 e of the inner teeth 109 on the inner side in the rotation axis direction. Is inclined in such a direction as to be located on the second tooth surface 109b side in the circumferential direction. The contour of each of the internal teeth 109 viewed from the tip side is a parallelogram. Therefore, the inner end portion 109e in the tooth width direction orthogonal to the tooth thickness direction of the inner tooth 109 has a triangular shape (hatched portion in FIG. 5) viewed from the tooth tip side. That is, when attention is paid to the inner end portion 109e of the inner tooth 109, the second tooth surface 109b tends to be shorter in width than the first tooth surface 109a, and the tooth thickness tends to become thinner toward the end portion.

  According to the configuration of FIG. 5, in the inner end 109e where the internal teeth 109 are liable to fall down, the outer end 9d of the inner teeth 109 becomes the first due to the rib effect of the portion of the inner teeth 109 on the second tooth surface 109b side. Deformation of the two tooth surfaces 9b can be suppressed, and the rims 13 and 14 can be prevented from being deformed by mutual interference between the pair of ring gears by being positioned at the center of the ring gear 105 in the rotation axis direction. In addition, at the outer end 109d of the internal tooth 109, the first tooth surface 109a that contacts the external tooth 7 of the planetary gear 4 is shorter than the second tooth surface 109b on the opposite side, so that the internal teeth are not easily deformed by falling. can do. Since other configurations are the same as those of the above-described embodiment, description thereof is omitted.

  In addition, this invention is not limited to embodiment mentioned above, The structure can be changed, added, or deleted. A part of the configuration in the embodiment can be arbitrarily extracted separately from the other configurations in the embodiment.

DESCRIPTION OF SYMBOLS 1 Planetary gear apparatus 3 Sun gear 4 Planetary gear 5,105 Ring gear 6,7 External tooth 7a First tooth surface 7b Second tooth surface 9,109 Internal tooth 9a, 109a First tooth surface 9b, 109b Second tooth surface 9d, 109d Out End 9e, 109e Inner end 11, 12 Helical gear

Claims (3)

A sun gear having external teeth;
A plurality of planetary gears having external teeth and meshing with the sun gear;
A ring gear having internal teeth and meshing with the planetary gear,
The ring gear is composed of at least one helical gear in which each of the internal teeth extends in a direction inclined with respect to the rotation axis direction of the ring gear,
Each of the internal teeth of the ring gear has a first tooth surface that abuts on the external teeth of the planetary gear, and a second tooth surface opposite to the first tooth surface,
The pressure angle of the second tooth surface is larger than the pressure angle of the first tooth surface,
Each of the external teeth of the planetary gear has a first tooth surface that contacts the internal teeth of the ring gear and a second tooth surface that contacts the external teeth of the sun gear on the opposite side of the first tooth surface. And
Each of the external teeth of the sun gear has a first tooth surface and a second tooth surface that contacts the external teeth of the planetary gear on the opposite side of the first tooth surface.
The pressure angle of the second tooth surface Puranetarigi Ya is much larger than the pressure angle of the first tooth surface before Symbol Puranetarigi Ya, and
Pressure angle of the second tooth surface of the sun gear is not greater than the pressure angle of the first tooth surface of the sun gear, the planetary gear unit.   2. The planetary gear device according to claim 1, wherein the ring gear is a double helical gear, and the at least one helical gear is a pair of helical gears arranged in parallel in the rotation axis direction.   In the double helical gear, the inner teeth of the inner teeth are positioned on the first tooth surface side in the circumferential direction of the ring gear relative to the inner ends of the inner teeth in the tooth width direction. The planetary gear device according to claim 2, wherein the planetary gear device is inclined in a direction.

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