JP5283223B2 - Internal gear - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal gear processed in a gear profile by which stress concentration is hard to generate in tooth, and a strength of the whole tooth can be improved. <P>SOLUTION: The internal gear, wherein: a dedendum side of tooth 2 of internal gear 1 is (1) smoothly connected to a tooth face 3; a first curved surface 4 profiled in protrusion in the same direction of the tooth face 3, (2) a plane 5 connected to this first curved surface 4 and (3) a second curved surface 6 which is smoothly connected to the plane 5 and profiled in convex in the same direction of the first curved surface 4 are formed; and in the plane 5, a virtual plane, in which an end of the first curved surface 4 side is extended, is formed so that it may cross a tooth profile center line 13 at an angle of 50 degrees. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an internal gear widely used in power transmission mechanisms such as automobiles, precision machines, industrial machines, and parts thereof.

  Conventionally, various devices for increasing the strength of teeth have been applied to gears used in power transmission mechanisms such as automobiles and precision machines.

  FIG. 8 shows the tooth profile of such a gear 100. The gear 100 shown in FIG. 8 has an arch-shaped curved surface 102 in which the shape of the tooth bottom side of the tooth 101 is close enough not to interfere with the tooth movement trajectory of the mating gear (pinion). The position of the cross section is made closer to the tooth tip side from P1 to P2, and the strength of the teeth is increased (see Patent Document 1).

JP-T-2004-519644

  However, the gear 100 shown in FIG. 8 is intended to improve the strength of the teeth 101 of the external gear, and is not intended to improve the strength of the teeth of the internal gear.

  Moreover, in the gear 100 shown in FIG. 8, the arcuate curved surfaces 102, 102 of adjacent teeth 101, 101 merge to form a pointed triangular apex 103 at the tooth bottom. Therefore, in the gear 100 shown in FIG. 8, stress tends to concentrate on the tooth bottom.

  Accordingly, an object of the present invention is to provide an internal gear that can reduce the concentration of stress on the tooth and improve the strength of the entire tooth by devising the shape of the tooth root side of the tooth.

The invention of claim 1 relates to an internal gear having a plurality of teeth formed on the inner peripheral side. In this invention, the tooth base side of the tooth is (1) a first curved surface that is smoothly connected to the tooth surface and is convex in the same direction as the tooth surface, and (2) the first curved surface. (3) An arc that is smoothly connected to this plane and that protrudes in the direction from the tooth tip to the tooth base, and protrudes in the same direction as the tooth surface and the first curved surface. The second curved surface is formed.

  According to a second aspect of the present invention, in the internal gear according to the first aspect of the present invention, the second curved surface is smoothly connected to the flat surface of the adjacent tooth.

  The invention of claim 3 is characterized in that the plane of the internal gear according to the invention of claim 1 or 2 is characterized. That is, in the present invention, the plane is characterized in that an imaginary plane obtained by extending an end of the first curved surface intersects the tooth profile center line at an angle of 50 °.

  The invention of claim 4 is characterized in that the radius of curvature of the first curved surface of the internal gear according to any one of claims 1 to 3 is provided. That is, in the present invention, the curvature radius of the first curved surface is 1 to 1 / 0.7 of the curvature radius of the second curved surface, and does not interfere with the movement locus of the teeth of the mating gear. It is characterized by its size.

  According to the present invention, the stress generated in the teeth is widely dispersed on the root side, and stress concentration is hardly generated in the teeth, so that the strength of the entire teeth can be improved.

It is a figure which shows a part of teeth (tooth perpendicular cross section) of the internal gear which concerns on embodiment of this invention. It is a figure which expands and shows a part (part shown by the arrow Y) of the tooth | gear of the internal gear of FIG. It is a figure (teeth perpendicular cross-sectional view) which shows the 1st formation process of the tooth profile shape which concerns on 1st Embodiment. It is a figure (teeth perpendicular cross-sectional view) which shows the 2nd formation process of the tooth profile shape concerning a 1st embodiment. It is a figure (teeth perpendicular cross-sectional view) which shows the 3rd formation process of the tooth profile shape which concerns on 1st Embodiment. It is a figure (teeth perpendicular cross-sectional view) which shows the 4th formation process of the tooth profile shape which concerns on 1st Embodiment. It is a tooth perpendicular sectional view of a tooth of a comparative example. It is a tooth perpendicular sectional view of the tooth of a conventional gear.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an enlarged view showing a part of teeth 2 of an internal gear 1 according to an embodiment of the present invention. FIG. 2 is an enlarged view showing the root side (portion indicated by arrow Y) of the tooth 2 of FIG. In the present embodiment, the internal gear 1 is made of a resin material (PA, POM, PPS, PPA, etc.) and is manufactured by injection molding.

  As shown in FIGS. 1 and 2, the tooth 2 of the internal gear 1 according to the embodiment of the present invention is devised in the shape of the root side of the involute tooth profile A, and is connected to the tooth surface 3 of the involute tooth profile A. The first curved surface 4, the flat surface 5 extending from the end of the first curved surface 4, and the end of the flat surface 5 of another adjacent tooth 2 that is smoothly connected to the end of the flat surface 5. And a second curved surface 6 connected smoothly. In FIG. 2, S1 indicates a connection point between the tooth surface 3 and one end of the first curved surface 4, and S2 indicates a connection point between the other end of the first curved surface 4 and one end of the flat surface 5. , S3 indicates a connection point between the other end of the planes 5 and 5 and the end of the second curved surface 6.

  The tooth profile shape of the tooth 2 of the internal gear 1 according to the present embodiment is determined as follows.

  First, in the tooth perpendicular cross section of FIG. 3, it contacts with the tooth bottom 7 of the involute tooth profile A and contacts with the tooth surfaces 3 and 3 forming the same tooth gap 8 of the adjacent teeth 2 and 2 and meshes with each other. Of the arcs that do not interfere with the tooth movement locus B of the gear, an arc having the maximum curvature radius R1 (an arc that is convex in the direction from the tooth tip to the tooth base and that is convex in the same direction as the tooth surface 3) ) For convenience of explanation, this arc is referred to as a root R11.

  Next, as shown in FIG. 4, an arc having a radius of curvature R2 that is 1 to 1 / 0.7 times as large as the radius of curvature R1 of the root R11, touching the tooth surface 3 and meshing with it. An arc that does not interfere with the tooth movement locus B of the gear (an arc that is convex in the same direction as the tooth surface 3) is obtained. For convenience of explanation, this arc is referred to as a tooth surface R12. In addition, the pressure angle of the teeth of the mating gear is 20 °.

  Next, as shown in FIG. 5, a tangent line 14 that contacts the tooth surface R12 and intersects the tooth profile center line 13 at an angle of θ = 50 ° is drawn.

  Next, as shown in FIG. 6, the tooth bottom R11 in contact with the tangent line 14 is drawn using the tooth bottom R11. Thereby, the tooth profile shape of the tooth 2 of the internal gear 1 shown in FIG. 2 is completed. Here, let tooth surface R12 be the shape of the 1st curved surface 4 in a tooth perpendicular section. Further, the tooth bottom R11 has the shape of the second curved surface 6 in the tooth perpendicular cross section. The tangent line 14 has one end portion in contact with the tooth surface R12 at the connection point S2 and the other end portion in contact with the tooth bottom surface R11 at the connection point S3 between the first curved surface 4 and the second curved surface 6. The shape of the tooth perpendicular section of the plane 5 is shown (see FIG. 2). In addition, the virtual plane which extended the edge part by the side of the 1st curved surface 4 cross | intersects the plane 5 at the angle of 50 degrees with respect to the tooth profile centerline 13 (refer FIG. 5). Further, in FIG. 6, the tooth surface 3 and the tooth surface R12 are in contact at the connection point S1.

Table 1 shows the Mises stress value on the root side of the tooth 2 shown in FIG. 7 (here, the tooth of the reference example) and the stress value on the root side of the tooth 2 of the present embodiment shown in FIG. The Mises stress value of the first curved surface 4, the Mises stress value of the flat surface 5, and the Mises stress value of the second curved surface 6) are shown in comparison. In the reference example shown in FIG. 7, the fillet R of the root of the tooth 2 is maximized so as not to concentrate stress on the bottom of the conventionally used internal gear. Yes, the root shape of the tooth gap 8 between the teeth 2 and 2 is an arc shape drawn by the root R11 (see FIG. 3). In addition, the tooth 2 of the reference example and the tooth 2 of the present embodiment have the same gear specifications except for the shape on the tooth base side. Each numerical value shown in Table 1 indicates a Mises stress value by simulation analysis (two-dimensional linear analysis (CAE)).

  As shown in Table 1, in the tooth 2 of the present embodiment, the stress is dispersed in each part of the first curved surface 4, the flat surface 5, and the second curved surface 6, and the Mises stress value of each part is that of the comparative example. It is smaller than the Mises stress value of the tooth 2, and at least the Mises stress value can be reduced by about 12% from the Mises stress value of the tooth 2 of the comparative example.

  As described above, according to the tooth profile of the internal gear 1 according to the present embodiment, stress concentration is unlikely to occur in the teeth 2 and the overall strength of the teeth 2 can be easily improved. Further, the tooth profile-shaped internal gear 1 of the present embodiment can reduce the maximum stress value generated in the tooth 2 as compared with the case where the tooth profile shape of the tooth 2 of the reference example is adopted.

(Modification of this embodiment)
Table 2 shows Mises stress values when the angle θ of the tangent line 14 of this embodiment is changed to 50 ° and the degrees θ of the tangent line 14 are 45 °, 55 °, 60 °, and 65 °. As shown in Table 2, the tooth 2 of the tooth profile shape with the angle of each tangent line 14 has a Mises stress value of 35.5 (MPa) of the tooth 2 of the comparative example (see Table 1), whereas the Mises stress The value can be reduced. Therefore, the teeth 2 of the internal gear 1 may appropriately change the angle θ of the tangent line 14 in the range of 45 ° to 65 °.

  The tooth profile of the internal gear according to the present invention can be widely applied as the tooth profile of a spur gear and a helical gear. The tooth shape of the internal gear according to the present invention is not limited to an internal gear formed of a resin material, and can be applied to a metal internal gear and an internal gear that is sintered.

  DESCRIPTION OF SYMBOLS 1 ... Internal gear, 2 ... Teeth, 3 ... Tooth surface, 4 ... 1st curved surface, 5 ... Plane, 6 ... 2nd curved surface, 13 ... Tooth profile center line, B ... Engagement partner Gear tooth movement trajectory

Claims (4)

In the internal gear having a plurality of teeth formed on the inner peripheral side,
The root side of the tooth is (1) a first curved surface that is smoothly connected to the tooth surface and is convex in the same direction as the tooth surface, and (2) a plane that is connected to the first curved surface. And (3) a second arc that is smoothly connected to the plane and is convex in the direction from the tooth tip to the tooth root , and is convex in the same direction as the tooth surface and the first curved surface. The curved surface of was formed,
An internal gear characterized by that. The second curved surface is also smoothly connected to the plane of the adjacent tooth;
The internal gear according to claim 1. The plane is formed such that an imaginary plane extending from the end of the first curved surface intersects the tooth profile center line at an angle of 50 °.
The internal gear according to claim 1 or 2, wherein The radius of curvature of the first curved surface is 1 to 1 / 0.7 of the radius of curvature of the second curved surface, and is a size that does not interfere with the movement locus of the teeth of the mating gear.
An internal gear according to any one of claims 1 to 3, wherein

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