Gear assemblies and their modification design methods

Abstract

This invention discloses a gear assembly and its modification design method. The gear assembly includes a driving gear and a driven gear. The driving gear has a plurality of drum-shaped teeth evenly distributed along its circumference, and at least one tooth surface of each drum-shaped tooth protrudes towards the adjacent drum-shaped tooth. The driven gear meshes with the driving gear and has a plurality of mating teeth corresponding to the plurality of drum-shaped teeth, and at least one tooth surface of each mating tooth is correspondingly recessed. This invention aims to solve the problems of existing double-drum-shaped gear assemblies where the amount of drum shape is difficult to calculate and select, easily leading to tooth meshing deformation or small meshing area affecting transmission stability, requiring repeated vehicle testing, which is time-consuming and labor-intensive.

Description

Technical Field

[0001] This invention relates to the field of transmission system technology, and specifically to a gear assembly and its modification design method. Background Technology

[0002] Cylindrical gears generally include two types: spur gears and helical gears. Their profile modification includes both tooth profile modification and tooth direction modification. According to design theories in gear handbooks or textbooks, tooth direction modification of cylindrical gears typically involves designing both meshing gears with a bulging tooth direction (bulging in the middle along the tooth length, with the modification curve being a circular arc, symmetrical about the tooth width centerline), commonly known as "bulging teeth." Bulbous tooth modification mainly involves removing a portion of material from both ends of the gear to thin it, causing the middle of the gear to bulge slightly (generally 0.01–0.08 mm). This avoids interference noise caused by deformation during meshing and ensures that the meshing pattern remains in the middle of the gear, preventing uneven loading and improving load-bearing capacity.

[0003] However, the calculation and selection of the camber amount in this traditional tooth-direction camber modification relies on the designer's experience. If the camber amount is too small, it is impossible to avoid gear meshing deformation, resulting in interference and abnormal noise; if the camber amount is too large, although the meshing spot is located in the middle of the tooth length, the meshing area is greatly reduced, which will disrupt the smoothness of gear transmission and increase noise. It is often necessary to repeatedly manufacture gears and install them on vehicles (machines) for verification to determine the optimal camber amount, which is time-consuming and labor-intensive. For helical cylindrical gears, after tooth-direction camber modification, experiments have shown that tooth surface scratches are easily generated. This is because helical cylindrical gears are subjected to axial and circumferential forces during meshing. The resultant force of these two forces pushes the gear teeth to slide along the tooth length direction, which will cause accelerated tooth surface wear, gear failure, and reduced gear life. Summary of the Invention

[0004] The main objective of this invention is to propose a gear assembly that addresses the problems of existing double-drum gear assemblies, such as the difficulty in calculating and selecting the drum shape, the tendency for tooth meshing deformation or small meshing area to affect transmission stability, and the need for repeated vehicle testing, which is time-consuming and labor-intensive.

[0005] To achieve the above objectives, the present invention provides a gear assembly comprising:

[0006] A drive gear has a plurality of drum-shaped teeth evenly distributed along its circumference, at least one tooth surface of each drum-shaped tooth protruding toward the adjacent drum-shaped tooth; and,

[0007] The driven gear meshes with the driving gear. The driven gear has multiple mating teeth corresponding to multiple drum-shaped teeth, and at least one tooth surface of each mating tooth is correspondingly recessed.

[0008] Optionally, the protruding tooth surface of each of the drum-shaped teeth is a first tooth surface, and the center of each first tooth surface and the straight line passing through the center of the two tooth surfaces of the corresponding drum-shaped tooth are spaced apart in the length direction of the corresponding first tooth surface.

[0009] Optionally, both tooth surfaces of each of the drum-shaped teeth are convex, and the convex directions are opposite to each other;

[0010] Each of the mating teeth has two recessed tooth surfaces corresponding to each of the mating teeth.

[0011] Optionally, the amount of the drum shape of the driving gear is greater than the amount of the concavity of the driven gear.

[0012] Optionally, the recessed tooth surface of each of the mating teeth is a second tooth surface, and the straight line between the centers of the two tooth surfaces of each of the mating teeth passes through the center of the corresponding second tooth surface.

[0013] This invention also proposes a method for modifying the shape of a gear assembly. Based on the aforementioned gear assembly, the tooth surface of each convexly arranged drum-shaped tooth is the first tooth surface, and the tooth surface of each concavely arranged mating tooth is the second tooth surface. The method for modifying the shape of the gear assembly includes the following steps:

[0014] Provides a first gear and a second gear that mesh with each other;

[0015] The relevant parameters of the first gear and the second gear are obtained to calculate the machining parameters of the first gear and the second gear. The machining parameters of the first gear include the amount of the bulging of the bulging teeth and the first arc radius of the first tooth surface. The machining parameters of the second gear include the amount of the concavity of the mating teeth and the second arc radius corresponding to the second tooth surface.

[0016] Based on the machining parameters of the first gear and the second gear, the teeth of the first gear and the second gear are machined respectively to obtain the driving gear and the driven gear.

[0017] Optionally, the center of each first tooth surface and the straight line passing through the center of the two tooth surfaces of the corresponding drum-shaped tooth are spaced apart in the length direction of the corresponding drum-shaped tooth;

[0018] The machining parameters of the first gear also include the offset distance corresponding to the center of the first tooth surface.

[0019] Optionally, the step of obtaining the relevant parameters of the first gear and the second gear to calculate the machining parameters of the first gear and the second gear includes:

[0020] The first tooth width and the set circumferential force of the first gear are obtained, and the bulging amount of the bulging tooth is calculated based on the first tooth width and the set circumferential force.

[0021] The radius of the first arc corresponding to the first tooth surface is calculated based on the drum shape and the first tooth width.

[0022] Based on the drum-shaped amount, the concavity of the mating tooth is calculated;

[0023] Obtain the second tooth width of the second gear, and calculate the second arc radius corresponding to the second tooth surface based on the second tooth width and the concavity.

[0024] Optionally, the step of obtaining the first tooth width and the set circumferential force of the first gear includes:

[0025] The first tooth width is obtained by measurement, and the pitch circle diameter and set torque of the first gear are directly obtained.

[0026] The set circumferential force is calculated based on the pitch circle diameter and the set torque.

[0027] Optionally, the step of obtaining the second tooth width of the second gear includes:

[0028] The second tooth width is calculated based on the first tooth width.

[0029] In the technical solution of the present invention, the gear assembly includes a driving gear and a driven gear that mesh with each other. When the driving gear and the driven gear mesh and transmit power, the convex tooth surface of the drum-shaped tooth corresponds to the concave tooth surface of the driven gear, thereby appropriately increasing the meshing area while avoiding tooth interference, resulting in a longer contact trace, smoother transmission, and less noise. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0031] Figure 1 A side view schematic diagram of an embodiment of the drum-shaped teeth of the gear assembly provided by the present invention;

[0032] Figure 2 A side view schematic diagram of an embodiment of the mating teeth of the gear assembly provided by the present invention;

[0033] Figure 3 A schematic diagram showing the structure of the two tooth surfaces of an existing double-drum tooth and the first and second tooth surfaces of the present invention;

[0034] Figure 4 A schematic flowchart of an embodiment of the gear assembly's drum-shaped tooth modification design method provided by the present invention.

[0035] Explanation of icon numbers:

[0036]

[0037]

[0038] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0040] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0041] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0042] However, the calculation and selection of the camber amount in this traditional tooth-direction camber modification relies on the designer's experience. If the camber amount is too small, it is impossible to avoid gear meshing deformation, resulting in interference and abnormal noise; if the camber amount is too large, although the meshing spot is located in the middle of the tooth length, the meshing area is greatly reduced, which will disrupt the smoothness of gear transmission and increase noise. It is often necessary to repeatedly manufacture gears and install them on vehicles (machines) for verification to determine the optimal camber amount, which is time-consuming and labor-intensive. For helical cylindrical gears, after tooth-direction camber modification, experiments have shown that tooth surface scratches are easily generated. This is because helical cylindrical gears are subjected to axial and circumferential forces during meshing. The resultant force of these two forces pushes the gear teeth to slide along the tooth length direction, which will cause accelerated tooth surface wear, gear failure, and reduced gear life.

[0043] In view of this, the present invention provides a gear assembly that can increase the contact area between the gear teeth and improve the smoothness of transmission. Figures 1 to 3 An embodiment of the gear assembly provided by the present invention.

[0044] Please refer to Figures 1 to 3 The gear assembly 100 includes a driving gear 1 and a driven gear 2. The driving gear 1 has a plurality of drum-shaped teeth evenly distributed along its circumference, and at least one tooth surface of each drum-shaped tooth protrudes toward the adjacent drum-shaped tooth. The driven gear 2 meshes with the driving gear 1 and has a plurality of mating teeth corresponding to the plurality of drum-shaped teeth, and at least one tooth surface of each mating tooth is correspondingly recessed.

[0045] In the technical solution of the present invention, the gear assembly 100 includes a driving gear 1 and a driven gear 2 that mesh with each other. When the driving gear 1 and the driven gear 2 mesh and transmit power, the convex tooth surface of the drum-shaped tooth corresponds to the concave tooth surface of the driven gear 2, thereby appropriately increasing the meshing area while avoiding tooth interference, lengthening the contact trace, making the transmission smoother, and reducing noise.

[0046] In one embodiment, when the driving gear 1 and the driven gear 2 are helical gears, the protruding tooth surface of each of the drum-shaped teeth is a first tooth surface 11. The center of each first tooth surface 11 and the straight line passing through the center of the two tooth surfaces of the corresponding drum-shaped teeth are spaced apart along the length direction of the corresponding first tooth surface 11. This makes the most protruding position of the first tooth surface 11 offset along the length direction of the drum-shaped teeth, thereby increasing the angle of the sliding force and ultimately greatly reducing the sliding force between the tooth surfaces, reducing tooth surface wear, and extending the gear life.

[0047] Specifically, in this embodiment, the two tooth surfaces of each of the drum-shaped teeth are convex, and the convex directions are opposite; the two tooth surfaces of each of the mating teeth are concave; thus, the transmission between the driving gear 1 and the driven gear 2 can be made smoother.

[0048] To avoid interference between the driving gear 1 and the driven gear 2, in this embodiment, the convexity of the driving gear 1 is greater than the concaveness of the driven gear 2, so that the first tooth surface 11 and the second tooth surface 21 can always maintain meshing transmission, avoiding the seizing situation between the driving gear 1 and the driven gear 2, ensuring smooth transmission, and extending service life.

[0049] In this embodiment, the recessed tooth surface of each mating tooth is the second tooth surface 21. The straight line connecting the centers of the two tooth surfaces of each mating tooth passes through the center of the corresponding second tooth surface 21. Therefore, the second tooth surfaces 21 are symmetrically arranged. The most recessed position of the second tooth surface 21 is the center of the second tooth surface 21. The most protruding position of the first tooth surface 11 is offset, thereby reducing the angle between the sliding force and the first tooth surface 11, thus reducing the sliding force and reducing the wear between the driving gear 1 and the driven gear 2, and extending the service life.

[0050] It should be noted that, referring to Figure 3 Given:

[0051] Circular force F m1 =F m2 =2T1 / d1, α2>α1

[0052] F y1 =F m1 / sinα1,F y2 =F m 2 / sinα2,

[0053] F can be obtained y2 <F y1 Therefore, the sliding force of this application is less than that of traditional tooth profiled gears. Through repeated experiments, the inventors have found that the sliding force of this application is reduced by 30% to 50%.

[0054] Based on the aforementioned gear assembly 100, this application also proposes a gear assembly modification design method, wherein the tooth surface of each convexly arranged drum-shaped tooth is the first tooth surface 11, and the tooth surface of each mating tooth is the second tooth surface 21. Please refer to... Figure 4 The gear assembly modification design method includes the following steps:

[0055] S10, providing a first gear and a second gear that mesh with each other;

[0056] S20. Obtain the relevant parameters of the first gear and the second gear to calculate the processing parameters of the first gear and the second gear. The processing parameters of the first gear include the amount of the bulging of the bulging teeth and the first arc radius of the first tooth surface 11. The processing parameters of the second gear include the amount of the concavity of the mating teeth and the second arc radius corresponding to the second tooth surface 21.

[0057] In this embodiment, the teeth of the first gear can be machined according to the drum shape amount and the first arc radius to obtain the driving gear 1. Similarly, the teeth of the second gear can be machined according to the concave amount and the second arc radius to obtain the driven gear 2.

[0058] S30. Based on the machining parameters of the first gear and the second gear, the teeth of the first gear and the second gear are machined respectively to obtain the driving gear 1 and the driven gear 2.

[0059] It should be noted that this application does not limit the processing method of the first gear and the second gear, as long as the driving gear 1 and the driven gear 2 can be processed according to the corresponding processing parameters.

[0060] In the technical solution of the present invention, the relevant parameters of the first gear and the second gear are used to calculate the processing parameters of the first gear and the second gear. The corresponding first gear and the second gear are processed according to the processing parameters to obtain the driving gear 1 and the driven gear 2 that are still meshing with each other. There is no need to repeatedly install and test to adjust the meshing area of ​​the driving gear 1 and the driven gear 2. After the processing is completed and inspected, it can be used directly. The transmission is stable and the noise is low.

[0061] In another embodiment, since the center of each of the first tooth surfaces 11 and the straight line passing through the center of the two tooth surfaces of the corresponding drum-shaped tooth are spaced apart along the length direction of the corresponding drum-shaped tooth, the machining parameters of the first gear also include an offset distance of the center of the corresponding first tooth surface 11, the offset amount being T and the drum-shaped amount being B1, so that the first tooth surface 11, which is offset at the most prominent position, can be machined by using the offset distance, the drum-shaped amount, and the first arc radius. The specific value of the offset distance can be referred to in the following table:

[0062] B1 ≤10 10～20 20～35 35～55 ＞55 T 0.8～1.2 1.5～2.0 2.5～3.2 3.5～4.5 5

[0063] The mapping relationship between the offset distance and the first tooth width was obtained by the inventor through repeated experiments and is not limited here.

[0064] Specifically, the relevant parameters include the first tooth width, the set circumferential force, the torque acting on the first gear, and the pitch circle diameter of the first gear. Step S20 includes:

[0065] S31. Obtain the first tooth width and the set circumferential force of the first gear, and calculate the bulging amount of the bulging tooth based on the first tooth width and the set circumferential force.

[0066] Specifically, refer to Figure 1 The first tooth width is B1, and the set circumferential force is F. m The drum shape is D; it can be known that:

[0067]

[0068] S32. Calculate the first arc radius corresponding to the first tooth surface 11 based on the drum shape amount and the first tooth width;

[0069] Specifically, the relevant parameters include the drum-shaped evaluation length of the first gear, the evaluation length of the first tooth surface 11 being C1, and its relationship with the first tooth width being:

[0070] C1 = B1 × 0.9

[0071] According to geometric relationships:

[0072]

[0073] so:

[0074] S33. Calculate the concave amount of the mating tooth based on the drum-shaped amount;

[0075] Since the concave amount is less than the bulging amount, and the concave amount is S, based on the mapping relationship between the concave amount and the bulging amount (which the inventors determined through repeated experiments), it can be concluded that:

[0076] S = D / k (k is generally taken as 2.0 to 3.0)

[0077] S33. Obtain the second tooth width of the second gear, and calculate the second arc radius corresponding to the second tooth surface 21 based on the second tooth width and the concavity.

[0078] In this embodiment, refer to Figure 2 The second tooth width is B2, the second arc radius is R2, and the relevant parameters also include the evaluation length of the second tooth surface 21, which is C2. The relationship between the evaluation length C2 of the second tooth surface 21 and the second tooth width B2 is as follows:

[0079] C2 = B2 × 0.9 (mm)

[0080] Similarly, based on geometric relationships, the radius R2 of the second arc can be obtained as follows:

[0081]

[0082] Step S31 includes:

[0083] S311. The first tooth width is obtained by measurement, and the pitch circle diameter and set torque of the first gear are directly obtained.

[0084] Specifically, the torque is T1, and the pitch circle diameter is d1;

[0085] S312 calculates the set circumferential force based on the pitch circle diameter and the set torque.

[0086] We can know that: F m =2000×T1 / d1(N)

[0087] Step S33 includes:

[0088] S331. Calculate the second tooth width based on the first tooth width.

[0089] It should be noted that, in this embodiment, the second tooth width is B2, and the relationship between the second tooth width B2 and the first tooth width B1 is as follows:

[0090] B2 = B1 - Δ (When the width of the first tooth is less than 50mm, Δ is generally taken as 2 to 4mm)

[0091] Thus, the meshing area of ​​the driving gear 1 and the driven gear 2 is significantly increased, the contact trace is longer, the transmission is smoother, and the noise is lower. Furthermore, due to the concave shape of the second tooth surface 21 and the protruding and offset shape of the first tooth surface 11, the angle of the sliding force is increased, which ultimately greatly reduces the sliding force between the tooth surfaces, reduces tooth surface wear, and extends the gear life.

[0092] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A gear assembly, characterized in that, include: The driving gear has a plurality of drum-shaped teeth evenly distributed along its circumference, and at least one tooth surface of each of the drum-shaped teeth is provided to protrude toward the adjacent drum-shaped tooth; as well as, The driven gear meshes with the driving gear. The driven gear has multiple mating teeth corresponding to multiple drum-shaped teeth, and at least one tooth surface of each mating tooth is correspondingly recessed. Each of the drum-shaped teeth has a protruding tooth surface as a first tooth surface, and the center of each first tooth surface and the straight line passing through the center of the two tooth surfaces of the corresponding drum-shaped tooth are spaced apart in the length direction of the corresponding first tooth surface. Both the driving gear and the driven gear are helical gears; Both tooth surfaces of each of the aforementioned drum-shaped teeth are convex, and the directions of the convexity are opposite to each other; Each of the mating teeth has two tooth surfaces that are concave; The diameter of the driving gear is greater than the concave diameter of the driven gear. The recessed tooth surface of each of the mating teeth is the second tooth surface, and the straight line between the centers of the two tooth surfaces of each of the mating teeth passes through the center of the corresponding second tooth surface.

2. A method for modifying the shape of a gear assembly, based on the gear assembly as described in claim 1, characterized in that, The tooth surface of each drum-shaped tooth with a convex arrangement is the first tooth surface, and the tooth surface of each mating tooth with a concave arrangement is the second tooth surface. The modification design method of the gear assembly includes the following steps: Provides a first gear and a second gear that mesh with each other; The relevant parameters of the first gear and the second gear are obtained to calculate the machining parameters of the first gear and the second gear. The machining parameters of the first gear include the amount of the bulging of the bulging teeth and the first arc radius of the first tooth surface. The machining parameters of the second gear include the amount of the concavity of the mating teeth and the second arc radius corresponding to the second tooth surface. Based on the machining parameters of the first gear and the second gear, the teeth of the first gear and the second gear are machined respectively to obtain the driving gear and the driven gear.

3. The gear assembly modification design method as described in claim 2, characterized in that, The center of each first tooth surface and the straight line passing through the center of the two tooth surfaces of the corresponding drum-shaped tooth are spaced apart in the length direction of the corresponding drum-shaped tooth; The machining parameters of the first gear also include the offset distance corresponding to the center of the first tooth surface.

4. The gear assembly modification design method as described in claim 2, characterized in that, The step of obtaining the relevant parameters of the first gear and the second gear to calculate the machining parameters of the first gear and the second gear includes: The first tooth width and the set circumferential force of the first gear are obtained, and the bulging amount of the bulging tooth is calculated based on the first tooth width and the set circumferential force. The radius of the first arc corresponding to the first tooth surface is calculated based on the drum shape and the first tooth width. Based on the drum-shaped amount, the concavity of the mating tooth is calculated; Obtain the second tooth width of the second gear, and calculate the second arc radius corresponding to the second tooth surface based on the second tooth width and the concavity.

5. The gear assembly modification design method as described in claim 4, characterized in that, The steps of obtaining the first tooth width and setting the circumferential force of the first gear include: The first tooth width is obtained by measurement, and the pitch circle diameter and set torque of the first gear are directly obtained. The set circumferential force is calculated based on the pitch circle diameter and the set torque.

6. The gear assembly modification design method as described in claim 4, characterized in that, The step of obtaining the second tooth width of the second gear includes: The second tooth width is calculated based on the first tooth width.

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