Gear structure

Abstract

To provide a gear structure that can be obtained with excellent production efficiency.SOLUTION: In the gear structure, at least one of mutually meshing gears has a plurality of grooves on its tooth surface. The gear is a helical gear. The longitudinal direction of the grooves is orthogonal to the meshing progression line of the helical gear. At least one of the gears has walls at both ends in the longitudinal direction of the grooves.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a gear structure, and more particularly to a gear structure that can be obtained with excellent production efficiency. [Background technology]

[0002] Patent Document 1 discloses a gear that can reduce friction and improve metal fatigue life at the same time. This gear has a tooth contact region where the tooth surface comes into contact with the tooth surface of a mating gear, and 10% of the tooth contact region from the tooth base end of the gear, which is the meshing start position, toward the tooth tip is a non-dimpled region where no dimples are formed, and the remaining region is a dimpled region where multiple dimples are formed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-112243 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, when attempting to form multiple dimples on a gear tooth surface by laser processing as disclosed in Patent Document 1, one dimple is formed with one laser irradiation, and the cycle time for dimple processing is several hours per gear tooth, which creates the problem that excellent production efficiency cannot be achieved.

[0005] The present invention has been made in consideration of the problems inherent in the conventional technology, and has an object to provide a gear structure that can be obtained with excellent production efficiency. [Means for solving the problem]

[0006] As a result of extensive research into achieving the above-mentioned object, the inventors discovered that the above-mentioned object could be achieved by forming a plurality of grooves on the tooth surface of a gear, and thus completed the present invention.

[0007] That is, the gear structure of the present invention is characterized in that at least one of the gears that mesh with each other has a plurality of grooves on its tooth surface. Effect of the Invention

[0008] According to the present invention, since a plurality of grooves are formed on the tooth surface of the gear, a gear structure can be provided that can be obtained with excellent production efficiency. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view showing a schematic diagram of a first embodiment of a gear structure according to the present invention. [Diagram 2] 2 is an explanatory diagram showing a schematic view of a main part surrounded by line II of the gear structure shown in FIG. 1. [Diagram 3] FIG. 11 is an explanatory diagram illustrating a main part of a gear structure according to a second embodiment. [Figure 4] FIG. 11 is an explanatory diagram illustrating a main part of a gear structure according to a third embodiment. [Diagram 5] FIG. 13 is an explanatory diagram illustrating a schematic view of a main part of a gear structure according to a fourth embodiment. [Figure 6] FIG. 13 is a partial cross-sectional view showing a schematic view of a main part of a gear structure according to a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The gear structure of the present invention will be described in detail below with reference to the drawings. Note that the dimensional ratios of the drawings cited below are exaggerated for the convenience of explanation and may differ from the actual ratios.

[0011] (First embodiment) As shown in FIG. 1, the gear structure 10 of this embodiment includes a plurality of gears arranged in a gear box (not shown), specifically, a first gear 11, a second gear 12, a third gear 13, and a fourth gear 14. Although not shown in detail, the fourth gear 14 is arranged on the back side of the second gear 12 and coaxially therewith in FIG. 1. The first gear 11 and the second gear 12 mesh with each other, and the third gear 13 and the fourth gear 14 mesh with each other. In this way, the gear structure 10 has a three-shaft two-stage structure, and is used, for example, in a drive system for an automobile. Moreover, these gears (11, 12, 13, 14) in the illustrated example are helical gears, and are formed of, for example, a metal material such as iron. Furthermore, these gears are lubricated by a lubricating oil held in a gear box (not shown). As such a lubricating oil, a conventionally known lubricating oil that can be used in a gear box can be used.

[0012] As shown in FIG. 2, the second gear 12 has a plurality of grooves 122b on its tooth surface 122a, which meshes with the first gear (not shown) and comes into contact with it via an oil film of lubricating oil. The longitudinal direction of the plurality of grooves 122b, indicated by the arrow Z in the figure, is parallel to the meshing progression line A of the second gear (helical gear) 12. Examples of the cross-sectional shape of the groove 122a include a U-shape, a V-shape, and a rectangular shape. The entrance width of the groove 122a is preferably, for example, about 200 nm to 30 μm. The arrow Y in the figure indicates the tooth depth direction, and the arrow X indicates the tooth width direction.

[0013] Next, the advantages of this embodiment will be described. According to this embodiment, since multiple grooves 122b are formed on the tooth surface 122a of the second gear 12, the cycle time for groove processing by laser processing can be reduced to several minutes per gear tooth. This reduces the cycle time to about 1 / 10 of the cycle time for dimple processing by laser processing, and has the advantage that a gear structure can be obtained with excellent production efficiency.

[0014] In addition, according to this embodiment, the lubricating oil is held by the above-mentioned grooves 122b, so that an oil film necessary for lubrication can be formed on the tooth surface. This has the advantage of reducing friction loss and metal-to-metal contact in the gear structure, thereby improving transmission efficiency and metal fatigue life.

[0015] 3 to 6 are diagrams for explaining the gear structures of the second to fifth embodiments. In the following embodiments, the same components as those in the first embodiment are given the same reference numerals, and detailed descriptions of the invention are omitted.

[0016] Second embodiment Fig. 3 is an explanatory diagram showing a schematic view of a main part of the gear structure of the second embodiment at the same position as the part surrounded by line II in Fig. 1. As shown in Fig. 3, the gear structure of this embodiment has the same structure as the gear structure 10 of the first embodiment, except that the longitudinal direction of the multiple grooves 122b is perpendicular to the meshing progression line A of the second gear (helical gear) 12, which is shown by the two-dot chain line in the figure.

[0017] Next, the advantages of this embodiment will be described. According to this embodiment, the multiple grooves 122b are formed on the tooth surface 122a of the second gear 12 so that the longitudinal direction of the multiple grooves 122b is perpendicular to the meshing progression line A described above. This makes it more difficult for the lubricating oil to be discharged along the grooves than in the first embodiment, and the lubricating oil is compressed, resulting in a larger dynamic pressure effect. This has the advantage of reducing the friction coefficient by about 20% compared to the first embodiment.

[0018] Third embodiment Fig. 4 is an explanatory diagram showing a schematic view of a main part of the gear structure of the third embodiment at the same position as the part surrounded by line II in Fig. 1. As shown in Fig. 4, the gear structure of this embodiment has the same structure as the gear structure of the second embodiment, except that the second gear 12 has walls 122A at both ends in the longitudinal direction of the groove 122b.

[0019] Next, the advantages of this embodiment will be described. According to this embodiment, a plurality of grooves 122b are formed on the tooth surface 122a of the second gear 12 so that walls 122A are formed at both ends of the groove 122b in the longitudinal direction. This makes it more difficult for the lubricant to be discharged from both ends of the groove in the longitudinal direction than in the second embodiment. In other words, side leakage of the lubricant is suppressed or prevented, the lubricant is more compressed, and the dynamic pressure effect is greater. This has the advantage of reducing the friction coefficient by about 16% compared to the second embodiment.

[0020] (Fourth embodiment) The upper view of Figure 5 is an explanatory diagram that shows typically the meshing state between the first gear and the second gear in the gear structure of the fourth embodiment, the central view of Figure 5 is an explanatory diagram that shows typically the main parts of the first gear in the upper view of Figure 5, and the lower view of Figure 5 is an explanatory diagram that shows typically the main parts of the second gear in the upper view of Figure 5.

[0021] As shown in FIG. 5, the gear structure of this embodiment has the same structure as the gear structure of the third embodiment, except that both the first gear 11 and the second gear 12 have multiple grooves (111b, 122b) in the tooth tip side region (111c, 122c) from the center to the tooth tip in the tooth depth direction (direction indicated by arrow Y in the figure) of their tooth surfaces (111a, 122a).

[0022] Next, the advantages of this embodiment will be described. According to this embodiment, multiple grooves 111b, 122b are formed in the tooth tip side regions 111c, 122c from the center to the tooth tip in the tooth depth direction (direction indicated by arrow Y in the figure) of both tooth flanks 111a, 122a of the gears 11, 12, so there is no need to form grooves on the tooth base side where the laser irradiation light is likely to be blocked by adjacent teeth in laser processing. This has the advantage of improving processability in addition to the advantages of the third embodiment.

[0023] Fifth embodiment Fig. 6 is a partial cross-sectional view of a main part of the gear structure of the fifth embodiment, cut perpendicularly to the face width direction. As shown in Fig. 6, the gear structure of this embodiment has the same structure as the gear structure of the third embodiment, except for the following configurations (1) to (3).

[0024] Configuration (1): The second gear 12 (tooth 122) has a tooth surface 122a that is convex toward the tooth groove 12a.

[0025] Configuration (2): The second gear 12 (teeth 122) has a plurality of grooves 122b in a central portion 122B in the tooth depth direction (direction indicated by arrow Y in the figure) of a tooth surface 122a.

[0026] Configuration (3): In a cross section perpendicular to the tooth width direction (a direction perpendicular to the paper surface in Figure 6), the tooth flank line 122d corresponding to the tooth flank 122a has a central line 122e located in the central portion 122B and having a large radius of curvature, and end lines 122f connected to both ends of the central line 122e and having a small radius of curvature smaller than that of the central line.

[0027] Next, the advantages of this embodiment will be described. According to this embodiment, since the second gear 12 has a plurality of grooves formed in the central portion 122B of the convex tooth surface 122a corresponding to the tooth surface line 122d having the above-mentioned central portion line 122e and end portion line 122f, it is not necessary to form grooves in any portion other than the central portion 122B where the contact load is large. This has the advantage that a gear structure can be obtained with higher production efficiency than the third embodiment. Note that such tooth surfaces and grooves can be formed, for example, by adjusting the intensity of the laser irradiation light in the laser processing.

[0028] Although the present invention has been described above with reference to some embodiments, the present invention is not limited to these, and various modifications are possible within the scope of the gist of the present invention.

[0029] The gist of the present invention is that a plurality of grooves are formed on the tooth surface of a gear to provide a gear structure that can be obtained with excellent production efficiency.

[0030] Therefore, in the above embodiment, the gear is a helical gear, but the present invention is not limited to this. For example, the gear may be a spur gear or a gear of another shape.

[0031] In the above embodiment, the gear structure 10 has a three-shaft, two-stage structure and is used in an automobile drive system, such as a reducer that transmits the power of a drive motor to a drive shaft, but the present invention is not limited to this. In the present invention, for example, the gear structure 10 may be used in a speed increaser that transmits engine power to a generator motor. These may also be combined and placed in a gear box. In the present invention, the gear structure may have a structure other than the three-shaft, two-stage structure.

[0032] Furthermore, in the above embodiment, for convenience of explanation, the case where a plurality of grooves 122b is formed on the tooth surface of the second gear 12 (more specifically, the tooth surface 122a of the tooth 122) and the case where a plurality of grooves 111b is formed on the tooth surface of the first gear 11 (more specifically, the tooth surface 111a of the tooth 111) are exemplified, but the present invention is not limited thereto. In the present invention, for example, a plurality of grooves may be formed only on the tooth surface of at least one of the third gear 13 and the fourth gear 14, or a plurality of grooves may be formed on the tooth surfaces of all the gears of the first gear to the fourth gear (11, 12, 13, 14). Of course, it goes without saying that it is preferable to form a plurality of grooves on the tooth surfaces of all the teeth of at least one gear selected from the first gear to the fourth gear (11, 12, 13, 14), and it is more preferable to form a plurality of grooves on the tooth surfaces of all the teeth of the gears that are located at the positions where a plurality of grooves need to be formed, taking into consideration the flow of lubricating oil in the gearbox.

[0033] Furthermore, in the above-mentioned fourth embodiment, the first gear 11 and the second gear 12 both have a plurality of grooves (111b, 122b) in the tooth tip side region (111c, 122c) from the center in the tooth depth direction of the tooth flank (111a, 122a) to the tooth tip, but the present invention is not limited to this. In the present invention, for example, any one of the first gear to the fourth gear (11, 12, 13, 14) may have a plurality of grooves in the tooth tip side region from the center in the tooth depth direction of the tooth flank.

[0034] Furthermore, in the above-mentioned fifth embodiment, the tooth surface 122a of the second gear has a plurality of grooves 122b in the center 122B in the tooth depth direction, but the present invention is not limited to this. In the present invention, for example, the tooth surface 122a of the second gear may have a plurality of grooves 122b in the center in the tooth width direction, or these may be combined. [Explanation of symbols]

[0035] 10 Gear Structure 11 First Gear 11a Tooth groove 111,112 teeth 111A Wall 111a Tooth surface 111b Groove 111c Tooth tip area 12 2nd Gear 12a Tooth groove 121,122,123 teeth 122A Wall 122B Central part 122a Tooth surface 122b Groove 122c Tooth tip area 122d Tooth flank line 122e Central line 122f End Line 13 3rd Gear 14 4th Gear A Meshing Progression Line

Claims

1. A gear structure characterized in that at least one of the gears that mesh with each other has a plurality of grooves on its tooth surface.

2. The gear is a helical gear, The longitudinal direction of the plurality of grooves is perpendicular to the meshing progression line of the helical gear.

2. A gear structure according to claim 1.

3. 3. The gear structure of claim 2, wherein said at least one gear has walls at both longitudinal ends of said groove.

4. The gear structure according to any one of claims 1 to 3, characterized in that at least one of the gears has the plurality of grooves in a tooth tip side region from the center of the tooth flank in the tooth depth direction to the tooth tip.

5. At least one of the gears has a tooth surface that is convex toward the tooth groove side, and has the plurality of grooves at a central portion of the tooth surface in a tooth depth direction, A tooth flank line corresponding to the tooth flank in a cross section perpendicular to the tooth width direction has a center line located in the center portion and having a large radius of curvature, and end lines connected to both ends of the center portion and having a small radius of curvature smaller than that of the center line. A gear structure according to any one of claims 1 to 3.

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