Gear

Abstract

To provide a gear capable of suppressing resonance and reducing a gear noise level.SOLUTION: In the gear 1 in which a plurality of meshing teeth 3 are formed at a constant interval on an outer peripheral portion of a disc-shaped disc portion 2, and a plurality of lightening portions 4 are arranged on the disc portion 2 in a circumferential direction, the gear noise due to a change in rigidity in the circumferential direction can be suppressed by providing the lightening portions 4 because the interval between the lightening portions 4 in a predetermined circumferential direction of the disc portion 2 is different from that in another place in at least one place in the predetermined circumferential direction. Since an interval between the mutual lightening parts 4 is different from the other place in at least one place in the predetermined circumferential direction, rigidity of the gear 1 becomes uneven, and resonance is hardly caused. As a result, gear noise due to resonance can be reduced.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a gear having a structure for suppressing gear noise. [Background technology]

[0002] Various technologies have been proposed to suppress gear noise (sound and vibration) generated when two gears mesh. For example, in the vehicle gear described in Patent Document 1 and the vehicle meshing gear described in Patent Document 2, a plurality of through holes, each connecting an arc-shaped slit and a round hole, are arranged circumferentially in the disk portion between the central boss portion and the rim portion on which the teeth are formed. These through holes are portions that can be called lightening holes, and the rigidity of each portion of the disk portion is varied in a complex manner depending on the presence or absence and shape of the through holes. This is said to change the vibration characteristics, thereby suppressing gear noise. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-063790 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-247348 Summary of the Invention [Problem to be solved by the invention]

[0004] The through holes in the gears described in Patent Documents 1 and 2 are circular arc-shaped slits with both ends or one end thereof formed as round holes, and multiple through holes (three in the figures of Patent Documents 1 and 2) are provided at equal intervals in the circumferential direction of the disk portion. That is, in the gear structures described in Patent Documents 1 and 2, the disk portion can be divided into three regions based on the through holes, and because the through holes have the same shape, the rigidity of these regions is the same. Furthermore, the pattern of change in rigidity in the circumferential direction within each region is the same. In other words, the gear structures described in Patent Documents 1 and 2 have a structure in which the rigidity of the disk portion is periodic when viewed in the circumferential direction.

[0005] Incidentally, gear noise is not only generated by the repeated meshing of teeth, but can also occur as a result of resonance with vibrations transmitted from the outside. Generally, resonance in rotating bodies, including gears, is more likely to occur when the rigidity of the rotating body is point-symmetrical with respect to the center point, and such resonance can be identified as antinodes and nodes using integer-order circular vibration shape (mode shape) analysis, etc.

[0006] As described above, the stiffness of the gears described in Patent Documents 1 and 2 varies periodically in the circumferential direction, and the stiffness pattern is close to point symmetry, if not point symmetry, about the center point. Therefore, the gear structures described in Patent Documents 1 and 2 are prone to exciting resonance, which can result in increased gear noise.

[0007] The present invention has been made in light of the above technical problems, and has an object to provide a gear that can suppress resonance and reduce gear noise levels. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the present invention provides a gear having a disk-shaped disc portion on the outer periphery thereof with a plurality of meshing teeth formed at regular intervals, and a plurality of cutouts arranged in the circumferential direction on the disc portion, characterized in that the spacing between the cutouts in a predetermined circumferential direction of the disc portion is different at at least one point in the predetermined circumferential direction from other points. [Effects of the Invention]

[0009] In the gear of the present invention, the spacing between the recessed portions in a predetermined circumferential direction of the disk portion is different at at least one location in the predetermined circumferential direction from other locations. Therefore, by providing the recessed portions, gear noise due to changes in rigidity in the circumferential direction can be suppressed. In addition, because the spacing between the recessed portions in at least one location in the predetermined circumferential direction is different from other locations, the rigidity of the gear becomes non-uniform, making it less likely for resonance to occur. As a result, gear noise due to resonance can be reduced. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram illustrating a gear according to an embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] As shown in Fig. 1, a gear 1 according to an embodiment of the present invention has a disk-shaped disc portion 2 attached to a rotating shaft (not shown), and the two rotate together around the rotation axis. A plurality of meshing teeth 3 are formed at regular intervals on the outer periphery of the disc portion 2, and are adapted to mesh with another gear (not shown). Here, the gear shown in Fig. 1 is a spur gear whose tooth trace is a straight line parallel to the rotation axis, but is not limited to this.

[0012] Additionally, a plurality of oval-shaped lightening holes 4 are arranged in the circumferential direction at positions spaced a predetermined radial distance from the center point P of the disk portion 2. In the gear 1 of the present invention, the spacing between the lightening holes 4 in the predetermined circumferential direction of the disk portion 2 is different in at least one location in the predetermined circumferential direction from the other locations.

[0013] Next, the spacing between the cutouts 4 in the circumferential direction will be described. For example, as shown in FIG. 1, the disk portion 2 is divided into eight equal parts in the circumferential direction (the dividing lines are indicated by two-dot chain lines). The cutouts 4 are formed in prime-numbered regions clockwise from a predetermined region designated as a first region (i) in the circumferential direction from the first region. In this embodiment, the number of cutouts 4 is prime within the range from the first region to the eighth region, so there are four cutouts: a second region (ii), a third region (iii), a fifth region (v), and a seventh region (vii). By forming the cutouts 4 at prime-numbered positions, the spacing between the cutouts 4 is different from the other regions at at least one predetermined location in the circumferential direction.

[0014] In the gear 1 according to the embodiment of the present invention, the spacing between the cutouts 4 in a predetermined circumferential direction of the disk portion 2 is different at at least one location in the predetermined circumferential direction from other locations. Therefore, the provision of the cutouts 4 not only suppresses gear noise due to changes in rigidity in the circumferential direction, but also makes the rigidity of the gear 1 non-uniform, making it less likely to resonate, thereby reducing gear noise due to resonance.

[0015] The above-described embodiment is merely an example of how the present invention can be implemented, and is not intended to limit the present invention. For example, although the cutouts 4 are oval in shape in the embodiment, the shape is not limited thereto and may be a perfect circle or a shape that is not symmetrical in the radial direction. Essentially, it is sufficient that the spacing between the cutouts 4 is different at at least one location in a predetermined circumferential direction from the other locations. [Explanation of symbols]

[0016] 1. Gears 2 Disc section 3 Teeth 4. Hollowed-out section P center point

Claims

[Claim 1] A gear having a disk-shaped disc portion on the outer periphery of which a plurality of meshing teeth are formed at regular intervals, and a plurality of recesses are arranged in the circumferential direction on the disc portion, The intervals between the recessed portions in a predetermined circumferential direction of the disk portion are different at at least one location in the predetermined circumferential direction from the other locations. A gear characterized by:

Images