Duplicate gear structure

Abstract

The utility model relates to the technical field of gears, in particular to a duplicate gear structure. Comprising a large gear, a small gear and supporting webs, the small gear is connected to an inner ring of the large gear through the supporting webs, the supporting webs are arranged in the middle of the tooth width of the large gear and at the ends of the small gear, a middle hole used for installing a bearing is formed in the middle of the small gear and penetrates through the middle area of the small gear, and axial supporting ribs protruding inwards are arranged in the middle hole. And the axial supporting rib limits the mounting position of the bearing. According to the structure, the injection molding precision of the duplicate gear, especially the precision of a high-speed bevel gear, is improved, and better NVH experience is brought; the rigidity supporting uniformity in the tooth direction of the high-speed bevel gear of the duplicate gear is improved, so that when the duplicate gear is meshed with a metal gear, the high-stress contact area at the end is reduced, the contact abrasion area tends to the middle high-rigidity area, and the problems of early tooth surface pitting corrosion and abrasion are solved.

Description

TECHNICAL FIELD

[0001] The utility model relates to gear technology field, especially a kind of double gear structure. BACKGROUND

[0002] Plastic double gear is common in the wheel hub motor of electric power-assisted bicycle, because the size wheel size difference of double gear is not big, considering the thickness of rim and specific structure, the existing structure design is the connection of big wheel and small wheel by end face cantilever structure of big wheel, and there are several radial divergent reinforcing ribs between middle hole and rim, especially guarantee the axial and radial engagement support when high-speed helical gear engages;For the consideration of improving the injection precision of plastic gear, there is also an improved scheme that cancels the reinforcing rib between middle hole and high-speed helical gear rim, but the connection of big wheel and small wheel is by end face cantilever structure of big wheel.

[0003] The common problem of the above design is that the end face cantilever support structure of the big wheel and small wheel of double gear will affect the injection molding process of plastic gear, so that the tooth profile of big wheel at end face part shrinks seriously, which affects its precision quality, and causes poor precision of plastic double gear-big gear, which causes NVH problem;At the same time, the tooth shape and direction shrinkage are uneven, when the big wheel and metal gear are engaged, the strong support stiffness at end face will cause stress concentration, the contact high stress area is deviated to one side of big gear, which easily causes early tooth surface pitting and wear problem. UTILITY MODEL CONTENTS

[0004] The utility model provides a kind of double gear structure, to solve the problem of poor precision quality, uneven shrinkage, easy to cause pitting and wear etc.

[0005] The utility model provides a kind of double gear structure, including big gear, pinion, support web, the pinion is connected in the inner ring of big gear by support web, the support web is arranged in the middle of tooth width of big gear and the end of pinion, the middle of pinion is equipped with the middle hole for installing bearing, the middle hole is through in the middle area of pinion, the middle hole is equipped with the axial support rib that projects inwards, the axial support rib limits the installation position of bearing.

[0006] As a further improvement of the utility model, the tooth surface of the pinion and the inner ring of the big gear are separated by a separation area.

[0007] As a further improvement of the utility model, the axial support rib is located in the middle of the middle hole, and the plurality of bearings are respectively installed into the middle hole from both sides of the middle hole, and the two sides of the axial support rib respectively abut against the two bearings.

[0008] As a further improvement of the utility model, the axial support rib is located at one side end of the middle hole, a plurality of bearings are installed into the middle hole from the end of the other side of the middle hole side by side, and the axial support rib abuts against the bearings on the inside.

[0009] As a further improvement of the utility model, the end bottom surface of the pinion gear and the bottom of the support web form a support plane.

[0010] As a further improvement of the utility model, a reinforcing ring is arranged on the support plane.

[0011] As a further improvement of the utility model, the top of the support web is a plane extending from the pinion gear tooth surface to the inner ring of the gear.

[0012] As a further improvement of the utility model, the top of the support web is a boss structure, the upper bottom surface of the boss is connected with the end of the pinion gear, and the lower bottom surface of the boss is connected with the inner ring of the gear.

[0013] As a further improvement of the utility model, the pinion gear is a straight gear, and the gear is a helical gear.

[0014] The utility model discloses the beneficial effect is: this structure improves the injection precision of double gear, especially the precision of high-speed level helical gear, and better NVH experience is brought;The stiffness support uniformity of high-speed level helical gear of double gear is improved, so that when it is engaged with the metal gear, the high stress contact area of end portion is reduced, thereby making the contact wear area tend to the middle high stiffness area, and the early tooth surface pitting and wear problem is avoided. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is the front structure diagram of the first kind of implementation of the utility model double gear structure;

[0016] Figure 2 It is the back structure diagram of the first kind of implementation of the utility model double gear structure;

[0017] Figure 3 It is the structure section view of the first kind of implementation of the utility model double gear structure;

[0018] Figure 4 It is the front structure diagram of the second kind of implementation of the utility model double gear structure;

[0019] Figure 5 It is the structure section view of the second kind of implementation of the utility model double gear structure;

[0020] Figure 6 It is the back structure diagram of the third kind of implementation of the utility model double gear structure;

[0021] Figure 7 is the front structure diagram of the third embodiment of the double gear structure. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical scheme and advantages of the utility model more clearly, the following will be further described in detail in combination with the drawings and examples.

[0023] Example one:

[0024] As Figures 1 to 7 shown, the double gear structure comprises a large gear 1, a small gear 2 and a support web 3, the small gear 2 is connected to the inner ring of the large gear 1 through the support web 3, the support web 3 is arranged at the middle of the tooth width of the large gear 1 and the end of the small gear 2, the middle of the small gear 2 is provided with a middle hole 4 for mounting a bearing, the middle hole 4 penetrates the middle region of the small gear 2, an inwardly protruding axial support rib 5 is arranged in the middle hole 4, and the axial support rib 5 limits the mounting position of the bearing.

[0025] The middle support web 3 is a wall plate connecting the large and small gears 2, is distributed at the middle of the tooth width of the large gear 1 and the end of the small gear 2, improves the contact stress of the large gear 1, so that the contact wear area tends to the high rigidity area in the middle of the large gear 1, and the occurrence of serious corrosion and wear is avoided. The whole double gear is integrated, that is, the large gear 1, the small gear 2 and the support web 3 are integrally injection molded, and the rationality of the structural layout has a great influence on the working performance of the gear, so that the integrally injection molding is beneficial to the consistency of stress and transmission.

[0026] The tooth surface of the small gear 2 and the inner ring of the large gear 1 are separated by a separation area 6. The separation area 6 refers to the connection between the large and small gears 2, especially the connection between the end of the large gear 1 and the small gear 2 without any reinforcing support rib. When the large gear 1 is contracted in the stress direction, the contraction force does not tend to the end of the large gear 1, so that the problem of uneven contraction is avoided.

[0027] The axial support rib 5 is a ring-shaped reinforcing rib arranged in the middle hole 4 of the double gear, which is a support structure for limiting the mounting position of the bearing.

[0028] The small gear 2 is a spur gear, and the large gear 1 is a helical gear. The whole double gear can be made of plastic material, and the positions of the spur gear and the helical gear are used for meshing with the corresponding metal gear outside to realize driving.

[0029] For the transmission system with helical gear meshing in the first stage, the existing design has a high stress effect when initially entering the meshing due to the high rigidity support of the end face support web 3, which is easy to cause pitting and wear failure, and first occurs at one end of the large gear 1 near the position of the end face support web 3; while in the design of the present invention, the initial meshing entry or the exit at the end of the meshing are both weak rigidity support areas with low stress levels. Only in the middle of the tooth part is the stress high, which is conducive to eliminating the high stress area of ​​edge contact and improving the contact wear condition. On the other hand, the design of the present invention is also conducive to improving the injection molding process of the large gear 1, and solves the problems of the existing design of setting the support web 3 on the end face of the large gear 1, local injection molding shrinkage, and easy to cause poor tooth direction error.

[0030] Example 2:

[0031] Based on the first embodiment, Figures 1 to 3 As shown, the axial support rib 5 is located in the middle of the center hole 4. Multiple bearings are installed into the center hole 4 from both sides, and the two sides of the axial support rib 5 respectively support two bearings. The middle axial support rib 5 refers to an annular reinforcement rib in the middle area of ​​the duplex gear center hole 4, which divides the center hole 4 into two parts. The two parts can be installed with bearings separately. The two bearings are installed into the center hole 4 from both sides until they support the middle axial support rib 5. The axial support rib 5 serves as a segmented axial support and also provides axial positioning.

[0032] Example 3:

[0033] Based on the first embodiment, Figure 4 and Figure 5 As shown, the axial support rib 5 is located at one end of the central hole 4. Multiple bearings are installed side by side into the central hole 4 from the other end, with the axial support rib 5 supporting the bearings inside. The axial support rib 5 on the side acts as a rib for the central hole 4. When the bearing is installed from one side of the central hole 4, it presses against the axial support rib 5 on the side, limiting the assembly position of the bearing in the central hole 4. The axial support rib 5 on the side also supports the bearing.

[0034] Example 4:

[0035] On the basis of the first embodiment, for the case where the tooth diameter of the small gear 2 is not much different from the tooth diameter of the large gear 1, as shown in FIG. Figure 2 As shown, the bottom surface of the end of the pinion 2 forms a support plane with the bottom of the support web 3. The spacing between the support webs 3 is relatively short. The width of the support webs 3 is sufficient to provide support between the pinion 2 and the gear 1, so a flat structure can be used to meet the strength requirements.

[0036] At the same time, when the tooth diameter of the small gear 2 is not much different from that of the large gear 1,Figure 1 and Figure 4 As shown, the top of the support web 3 is a flat surface extending from the tooth surface of the pinion 2 to the inner ring of the large gear 1. A shorter support web 3 is sufficient to meet strength requirements, and the distance between the tooth surface of the pinion 2 and the inner ring of the large gear 1 is limited. Therefore, the top surface of the support web 3 adopts a flat structural design at this location.

[0037] Embodiment 5:

[0038] On the basis of the first embodiment, for the case where the tooth diameter of the small gear 2 is significantly different from the tooth diameter of the large gear 1, such as Figure 6 As shown, a reinforcement ring 7 is provided on the support plane. The spacing between the support webs 3 is relatively long, and the strength of the support webs 3 with a longer width is lower than that of the support webs 3 with a shorter spacing. Therefore, the reinforcement ring 7 is added to the plane of the support webs 3 to increase the strength of the support webs 3 and meet structural requirements.

[0039] like Figure 7 As shown, the top of the support web 3 is a boss 8. The upper bottom surface of the boss 8 is connected to the end of the pinion 2, and the lower bottom surface of the boss 8 is connected to the inner ring of the gear 1. The strength requirements for the longer-span support web 3 are relatively low, and the space between the tooth surface of the pinion 2 and the inner ring of the gear 1 is larger. Therefore, the boss 8 is used on the top of the support web 3 in this position. The stepped transition between the upper and lower bottom surfaces acts as a reinforcement ring 7, enhancing the structural strength of the top of the support web 3.

[0040] This double gear structure has the following advantages:

[0041] (1) The large and small wheels of the plastic double gear are connected and supported by the support web 3 of the middle part of the large gear 1 and the small gear 2, and there is no connecting rib or support between the end of the large gear 1 and the small gear 2. By optimizing the plastic gear structure, the uniformity of circumferential and axial deformation caused by local shrinkage during the injection molding process is improved, thereby improving the accuracy of high-speed helical gears.

[0042] (2) By optimizing the plastic gear structure, the connecting support structure of the helical gear and the spur gear of the duplex gear is changed from the end cantilever to the middle support of the helical gear, thereby improving the local contact pressure when the helical gear and the metal gear are engaged, especially the high contact stress when the end enters, so that the contact wear area tends to the middle high stiffness area, avoiding the occurrence of severe pitting and wear.

[0043] (3) The new plastic gear has a middle hole 4 structure, an axial support rib 5 structure is added to the middle part of the middle hole 4, two bearings can be installed into the middle hole 4 left and right to achieve the function of axial positioning, and can also provide axial support for the left and right bearings. The axial positioning problem of the middle hole 4 bearing is improved, and the risk of axial loosening of the bearing under extreme conditions is avoided. A shaft sleeve can also be installed between the two bearings to increase the span support.

[0044] The above is a further detailed description of the utility model in combination with specific preferred embodiments, and cannot be regarded as the specific implementation of the utility model being limited to these descriptions. For ordinary skilled persons in the technical field to which the utility model belongs, without departing from the concept of the utility model, a number of simple deductions or substitutions can also be made, and all of them should be regarded as belonging to the protection scope of the utility model.

Claims

1. A double gear structure characterized by comprising: The gear includes a large gear, a small gear, and a support web, the small gear is connected to the inner ring of the large gear through the support web, the support web is arranged in the middle of the tooth width of the large gear and the end of the small gear, the middle of the small gear is provided with a middle hole for mounting a bearing, the middle hole penetrates the middle area of the small gear, an inwardly protruding axial support rib is arranged in the middle hole, and the axial support rib limits the mounting position of the bearing.

2. The double gear structure according to claim 1, characterized by The tooth surface of the small gear and the inner ring of the large gear are separated by a separation area.

3. The double gear structure according to claim 1, wherein The axial support rib is located in the middle of the middle hole, a plurality of bearings are mounted into the middle hole from both sides of the middle hole, and the two sides of the axial support rib abut against the two bearings respectively.

4. The double gear structure according to claim 1, wherein The axial support rib is located at one side end of the middle hole, a plurality of bearings are mounted into the middle hole side by side from the end of the other side of the middle hole, and the axial support rib abuts against the bearings on the inner side.

5. The double gear structure according to claim 1, wherein The end bottom surface of the small gear and the bottom of the support web form a support plane.

6. The double gear structure according to claim 5, wherein A reinforcing ring is arranged on the support plane.

7. The double gear structure according to claim 1, wherein The top of the support web is a plane extending from the tooth surface of the small gear to the inner ring of the large gear.

8. The double gear structure according to claim 1, wherein The top of the support web is a boss structure, the upper bottom surface of the boss is connected to the end of the small gear, and the lower bottom surface of the boss is connected to the inner ring of the large gear.

9. The double gear structure according to any one of claims 1 to 8, characterized by The small gear is a straight gear, and the large gear is a helical gear.

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