Gear structure with special tooth profile structure

Abstract

The utility model provides a gear structure with a special tooth profile structure, and belongs to the technical field of gear transmission. Comprising at least two gears which are meshed with each other, and at the meshing point of the two gears which are meshed with each other, the tooth profile curvature centers of the two gears are located on the same side of the common tangent of the meshing point. By the adoption of the gear structure with the special tooth profile structure, the forming stability of an extrusion oil film on the friction surface in the gear transmission process can be improved, and therefore the abrasion resistance and bearing capacity of the gear are improved.

Description

Technical Field

[0001] This utility model relates to the field of gear transmission technology, and in particular to a gear structure with a special tooth profile. Background Technology

[0002] Mechanical transmission refers to the transmission of power and motion using mechanical means. Common types of mechanical transmission systems include gear drives, worm gear drives, belt drives, chain drives, and wheel trains. Among these, gear drives are the most widely used form of mechanical transmission. They offer relatively accurate transmission, high efficiency, compact structure, reliable operation, and long service life.

[0003] In related technologies, gear transmission mechanisms are line-contact high-pair mechanisms with high contact stress. Due to their surface geometry, it is difficult for an oil film to form when the two friction surfaces move relative to each other. Therefore, it is difficult to set the fluid lubrication state between the two gears, and they are usually in a mixed lubrication state. Under high loads, the rough surfaces can easily break the lubricating oil film, and even cause direct friction between protruding points. The friction and wear of the gear teeth under the above conditions directly affects the working efficiency and service life of the mechanical equipment, and thus affects the performance of the entire mechanical system. Utility Model Content

[0004] This utility model provides a gear structure with a special tooth profile, which can improve the stability of the oil film formation on the friction surface during gear transmission, thereby improving the wear resistance and load-bearing capacity of the gear. The technical solution is as follows:

[0005] A gear structure with a special tooth profile includes: at least two gears that mesh with each other, wherein at the meshing point of the two meshing gears, the centers of curvature of the tooth profiles of the two gears are located on the same side of the common tangent at the meshing point.

[0006] Optionally, the tooth profile of the gear is composed of alternating connections of tooth profiles of multiple internal teeth and tooth profiles of multiple external teeth.

[0007] Optionally, the tooth profile of the internal tooth is a concave arc shape, the chord length of the tooth profile of the internal tooth is 28% to 47% of the module of the gear, and the chord height is 1.1% to 4.3% of the module; the tooth profile of the external tooth is a convex arc shape, the chord length of the tooth profile of the external tooth is 44% to 51% of the module, and the chord height is 4.5% to 5.7% of the module.

[0008] Optionally, the chord angle of the tooth profile of the internal tooth is in the range of 13° to 25°, and the chord angle of the tooth profile of the external tooth is in the range of 33° to 40°.

[0009] Optionally, a tooth groove is provided between two adjacent tooth profiles, the depth of which ranges from 3.4% to 6% of the module of the gear.

[0010] Optionally, the two meshing gears have the same number of teeth.

[0011] Optionally, the two meshing gears may have different numbers of teeth.

[0012] Optionally, the hub of the gear is circular.

[0013] The beneficial effects of the technical solution provided by this utility model embodiment include at least the following:

[0014] The gear structure with a special tooth profile provided in this embodiment optimizes the tooth profile structure of the meshing gears, ensuring that the centers of curvature of the tooth profiles of the two meshing gears are located on the same side of the common tangent at the meshing point. Compared with conventional gears where the centers of curvature of the two tooth profiles are not on the same side of the common tangent after meshing, the overall radius of curvature is larger. According to Hertzian contact theory, under the same conditions, the larger the overall radius of curvature, the smaller the contact stress, and the greater the load-bearing capacity of the gear. On the other hand, with a larger overall radius of curvature, the lubricating oil at the meshing point is less likely to escape to the surrounding area after being pressurized, thus facilitating the formation of an oil film squeezed between the two tooth profiles, thereby reducing direct contact between the tooth surfaces, reducing friction and wear, and extending the service life of the gear. By ensuring the stability of the oil film formation on the friction surfaces during gear transmission, the wear resistance and load-bearing capacity of the gear are improved. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a three-dimensional structural diagram of a gear structure with a special tooth profile provided in an embodiment of this utility model;

[0017] Figure 2 This is an exploded view of the gear structure with a special tooth profile provided in this embodiment of the utility model;

[0018] Figure 3 This is a schematic diagram of a method for wearing a gear structure with a special tooth profile provided in an embodiment of this utility model;

[0019] Figure 4This is a schematic diagram of the gear structure with a special tooth profile provided in this embodiment of the present invention after it has been worn.

[0020] In the diagram: 1-Gear; 11-Internal tooth; 12-External tooth; 13-Tooth groove; 111-First tooth profile; 112-Second tooth profile; 121-Third tooth profile; 122-Fourth tooth profile; o-Meshing point; λ-Common tangent. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this utility model clearer, the embodiments of this utility model will be described in further detail below with reference to the accompanying drawings.

[0022] Figure 1 This is a three-dimensional structural diagram of a gear structure with a special tooth profile provided in an embodiment of this utility model; Figure 2 This is an exploded view of the gear structure with a special tooth profile provided in this embodiment of the utility model; Figure 3 This is a schematic diagram of a method for wearing a gear structure with a special tooth profile provided in an embodiment of this utility model; Figure 4 This is a schematic diagram of the gear structure with a special tooth profile provided in this embodiment of the present invention after it has been worn. Figures 1 to 4 As shown, this embodiment of the present invention provides a gear structure with a special tooth profile. It includes at least two gears 1 that mesh with each other. At the meshing point of the two meshing gears 1, the centers of curvature of the tooth profiles of the two gears 1 are located on the same side of the common tangent at the meshing point.

[0023] In this embodiment of the utility model, reference is made to Figure 1 As shown, the tooth profiles of both gears 1 are composed of alternating connections of tooth profiles of multiple internal teeth 11 and multiple tooth profiles of external teeth 12. The two meshing gears 1 are denoted as 1a and 1b, respectively. The tooth profiles of the two gears 1 mesh at point o, λ is the common tangent line of the two tooth profiles passing through point o, and ρ1 and ρ2 are the centers of curvature of the two tooth profiles, located on the same side of the common tangent line λ. Compared to conventional gears where the centers of curvature ρ1 and ρ2 are not on the same side of the common tangent line λ, the combined radius of curvature is larger. According to Hertzian contact theory, under the same conditions, a larger combined radius of curvature results in lower contact stress and a greater load-bearing capacity of the gear. Furthermore, a larger combined radius of curvature makes it less likely for the lubricating oil at the meshing point o to dissipate around the meshing point o after being pressurized, thus facilitating the formation of a squeezed oil film between the two tooth profiles. This reduces direct contact between the tooth surfaces, lowers friction and wear, and extends the service life of gear 1. By ensuring the stability of the oil film formed on the friction surface during gear transmission, the wear resistance and load-bearing capacity of the gears can be improved.

[0024] Furthermore, the tooth profile design process of gear 1 in this gear structure with a special tooth profile is explained. First, the definitions of pitch point, pitch line, normal vector, and pressure angle are given. The pitch point is the instantaneous center of relative velocity when the two gears 1 mesh, such as... Figure 1 As shown at point Q, vector V represents the instantaneous velocity of that node. The pitch line is the trajectory of the node of gear 1 within one meshing cycle in a reference frame that is stationary relative to one of the gears. The dashed lines corresponding to C1 and C2 in the figure represent the pitch lines of both gears 1. The normal vector is the vector pointing from the node to the meshing point o, and its magnitude is equal to the distance between the node and the meshing point. The pressure angle is the angle between the normal vector and the instantaneous motion direction of the node, as shown in the figure. Figure 1 The included angle α is shown in the figure.

[0025] For example, in this embodiment of the invention, the hub of gear 1 can be circular, that is, the optimized tooth profile structure is applied to a regular gear, and its pitch line is also circular. The number of teeth among the multiple gears 1 that make up the gear structure can be the same or different, so as to realize the transmission and speed adjustment after the gear set is formed by meshing. In other possible implementations, the optimized tooth profile structure can also be applied to meshing non-meshing gears, which will not be elaborated in this invention.

[0026] For example, taking a gear structure composed of two gears 1 as an example, given the pitch radius R, the number of teeth of gear 1, and the variation law of the pressure angle α (β), the profile of gear 1 is calculated according to the tooth profile parametric equation. Then, based on the meshing conditions and the tooth ratio, the profile of the other meshing gear 1 is obtained. This results in two gears 1 used to form the gear structure, where the center of curvature of the tooth profiles at the meshing point o is on the same side of the common tangent, which is conducive to the formation of a "squeezed oil film" and has the characteristics of wear resistance and high load-bearing capacity. The process of obtaining the profiles of the two meshing gears is given below.

[0027] First, we give the system of parametric equations for any tooth profile with respect to the parameter β:

[0028] α=α(β)(1)

[0029] p=abs(∫R*cos(α)dβ)(2)

[0030] x=R*cos(β)-p*sin(α+β)(3)

[0031] y=R*sin(β)+p*cos(α+β)(4)

[0032] In the above formula, a rectangular coordinate system is established based on the profile plane of gear 1, x and y are the horizontal and vertical coordinates of any point on the tooth profile, R is the pitch line radius, and equation (1) is a function of the pressure angle α with respect to the parameter β, and is a linear function with respect to α1, α2, α3, and α4. Specifically, α1, α2, α3, and α4 are functions whose domain and range are both in the interval [0,1]. It must satisfy condition A: if the "α(β)+β" corresponding to one tooth profile is a monotonically increasing function, then the "α(β)+β" corresponding to the other tooth profile meshing with it is a monotonically decreasing function; if the "α(β)+β" corresponding to one tooth profile is a monotonically decreasing function, then the "α(β)+β" corresponding to the other tooth profile meshing with it is a monotonically increasing function. That is, the derivatives of the pressure angle functions of the two meshing tooth profiles are on both sides of the line α(β)=-1, thus ensuring that the two tooth profiles are on the same side of the common tangent. Designers can first determine the function form, for example, α1, α2, α3, α4 = k0*(u) + k1, u∈[0,1], where k0 and k1 are constants. Designers can then uniformly select multiple sets of k0 and k1 values ​​within the interval [-1,1] and examine whether they satisfy condition A, thus obtaining some α(β) functions. α1, α2, α3, α4 can also be functions obtained through polynomial fitting or piecewise polynomial fitting of points with both x and y coordinates in the interval [0,1]. Moving these points yields a series of functions, and similarly, examining whether they satisfy condition A yields the corresponding α(β) functions.

[0033] Furthermore, the profile of gear 1 is obtained based on the above parametric equations:

[0034] First, take m values ​​of β uniformly in the interval [0, ε1Ф0], and calculate the coordinates of the m points according to equations (1) to (4). Connect these points to obtain the first tooth profile line 111. At this time, α(β) = π - π / 2 * α1(β / (ε1 * Ф0)), the lower limit of the integral of equation (2) is 0, and the upper limit is β.

[0035] Then, take m values ​​of β uniformly in the interval [Ф0-ε2Ф0,Ф0], and calculate the coordinates of the m points according to equations (1) to (4). Connect these points to obtain the second tooth profile 112. At this time, α(β)=π / 2*α2((Ф0-β) / (ε2*Ф0)), the lower limit of the integral of equation (2) is Ф0, and the upper limit is β;

[0036] Then, take m values ​​of β uniformly in the interval [Ф0, ε3(2*π / N-Ф0)+Ф0], and calculate the coordinates of the m points according to equations (1) to (4). Connect these points to obtain the third tooth profile 121. At this time, α(β)=-π+π / 2*α3((β-Ф0) / (ε3*(2*π / N-Ф0))), the lower limit of the integral of equation (2) is Ф0, and the upper limit is β;

[0037] Next, take m values ​​of β uniformly in the interval [2*π / N-ε4(2*π / N-Ф0),2*π / N], and calculate the coordinates of the m points according to equations (1) to (4). Connect these points to obtain the fourth tooth profile.

[0038] 122, at this time, α(β)=-π / 2*α4((2*π / N-β) / (ε4*(2*π / N-Ф0))), the lower limit of integration of equation (2) is 2*π / N, and the upper limit is β.

[0039] In the above, constants m and N are positive integers, and Ф0 is a constant greater than 0 and less than 2*π / N, generally taken as Ф0=π / N. ε1, ε2, ε3, and ε4 are constants greater than 0, generally taken as ε1, ε2, ε3, and ε4=1, in which case the number of meshing points is 2. The first tooth profile 111, the second tooth profile 112, the third tooth profile 121, and the fourth tooth profile 122 are arranged in a circular array with a span of 360° and a quantity of N, resulting in N internal teeth 11 composed of the first tooth profile 111 and the second tooth profile 112, and N external teeth 12 composed of the third tooth profile 121 and the fourth tooth profile 122. The internal and external teeth are alternately connected and tooth grooves 13 are cut out to form the outline of the entire gear 1. For example, in this embodiment of the present invention, by providing a tooth groove 13 structure between adjacent tooth profiles, interference between the tooth tip and the hub body is avoided when the two gears 1 mesh with each other, which can also reduce the overall weight of the gears and facilitate installation and transportation. At the same time, it can block and isolate the vibration generated during the meshing of the tooth profiles, and reduce the noise generated when the gears are running.

[0040] In summary, as long as the number of teeth N, pitch radius R, Ф0, ε1, ε2, ε3, ε4, α1, α2, α3, and α4 of the gear are given, the profile of the gear 1a can be obtained.

[0041] Finally, based on the meshing conditions and gear ratio, the profile of the other gear 1b is determined. The condition for correct meshing of the two gears 1a and 1b is:

[0042] (1)R A Ф0 A +R B Ф0 B =2*πR A / N A =2*πR B / N B ;

[0043] (2)ε1 A =ε4 B ε2 A =ε3 B ε3 A =ε2 B ε4 A =ε1B ;

[0044] (3)α1 A (u)=α4 B (u), α2 A (u)=α3 B (u), α3 A (u)=α2 B (u), α4 A (u)=α1 B (u), u∈[0,1];

[0045] In the above conditions, the superscript "A" indicates the relevant parameters of gear 1a, and the superscript "B" indicates the relevant parameters of gear 1b. Based on the meshing condition, only the N value of the first gear 1a needs to be given. A R A Ф0 A ε1 A ε2 A ε3 A ε4 A α1 A α2 A α3 A α4 A and the number of teeth ratio N A / N B Then you can find the R of the other gear. B N B Ф0 B ε1 B ε2 B ε3 B ε4 B α1 B α2 B α3 B α4 B Then, by using the aforementioned formulas (1) to (4) to obtain the process of obtaining gear 1a, the profile of another gear 1b is obtained.

[0046] Furthermore, in this embodiment of the invention, two gear structures are designed based on the above conditions. In the first embodiment, N is taken as... A =20, R A =10, Ф0 A =π / N A =π / 20, N B =11, then R B =R A *N B / N A =5.5, Ф0 B =(2*πR) A / N A -RA Ф0 A ) / R B =π / 11. Take ε1 A ε2 A ε3 A ,

[0047] ε4 A ε1 B ε2 B ε3 B ε4 B =1; α1 A (u), α2 A (u), α3 A (u), α4 A (u), α1 B (u),

[0048] α2 B (u), α3 B (u), α4 B α(u) = 0.45u, u∈[0,1]. α(u) is a linear function that can be changed according to actual needs, altering the tooth profile shape by changing the scaling factor. 20 points are evenly selected along each tooth profile line, i.e., m = 20. The final meshing condition of the two gears is as follows: Figure 3 As shown.

[0049] Further, in this embodiment, the endpoints of the tooth profile, that is, the two endpoints of the first tooth profile 111 or the second tooth profile 112, or the two endpoints of the third tooth profile 121 and the fourth tooth profile 122, are taken as chords, and the maximum distance from a point on the tooth profile to the chord is the chord height. The tooth profile of the internal tooth 11 is a concave arc, the chord length of the tooth profile of the internal tooth 11 is 28% to 47% of the module of gear 1, and the chord height is 1.1% to 4.3% of the module of gear 1; the tooth profile of the external tooth 12 is a convex arc, the chord length of the tooth profile of the external tooth 12 is 44% to 51% of the module of gear 1, and the chord height is 4.5% to 5.7% of the module of gear 1.

[0050] Furthermore, the starting point of the chord is on the pitch line, and the angle between the radius passing through this point and the chord is called the chord angle, which is an acute angle. The chord angle of the tooth profile of the internal tooth 11 ranges from 13° to 25°, and the chord angle of the tooth profile of the external tooth 12 ranges from 33° to 40°.

[0051] In the second embodiment, N is taken as A =60, R A =10, Ф0 A =π / N A =π / 60, N B =30, then R B =R A *N B / N A =5, Ф0 B =(2*πR) A / N A -R A Ф0 A ) / R B =π / 30. Take ε1 A ε2 A ε3 A ε4 A ,

[0052] ε1 B ε2 B ε3 B ε4 B =2; α1 A (u), α2 A (u), α3 A (u), α4 A (u), α1 B (u), α2 B (u),

[0053] α3 B (u), α4 B (u)=α(u)=-0.23810u^4+0.36247u^3+0.42658u^2-0.85095u

[0054] +0.5, u∈[0,1], α(u) is a polynomial fitting function passing through the points (0,0.5), (0.22924,0.33105), (0.48793,0.21496), (0.79238,0.18003), and (1,0.2). The tooth profile shape can be changed according to actual needs by moving the fitting points. 20 points are evenly selected on each tooth profile line, i.e., m=20. The final meshing condition of the two gears is as follows: Figure 4 As shown.

[0055] It should be noted that the concave and convex shape of the tooth profile in the second embodiment, as well as the relationship between its chord height, chord length and chord angle, are adaptively transformed according to the actual calculation results and requirements. As long as the curvature centers of the tooth profiles of the two gears 1 are ultimately located on the same side of the common tangent at the meshing point, this embodiment of the present invention does not limit this.

[0056] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains. The terms “first,” “second,” and similar terms used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an” or “a” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “comprising” or “including” and similar terms mean that the elements or objects preceding “comprising” or “including” encompass the elements or objects listed following “comprising” or “including” and their equivalents, and do not exclude other elements or objects. The terms “connected” or “linked” and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms “upper,” “lower,” “left,” and “right” are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0057] The above description is only an optional embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A gear structure with a special tooth profile, characterized in that, include: At least two gears (1) mesh with each other, and at the meshing point of the two meshing gears (1), the centers of curvature of the tooth profiles of the two gears (1) are located on the same side of the common tangent at the meshing point.

2. The gear structure with a special tooth profile according to claim 1, characterized in that, The tooth profile of the gear (1) is composed of alternating tooth profiles of multiple internal teeth (11) and multiple external teeth (12).

3. The gear structure with a special tooth profile according to claim 2, characterized in that, The tooth profile of the internal tooth (11) is a concave arc shape, the chord length of the tooth profile of the internal tooth (11) is 28% to 47% of the module of the gear (1), and the chord height is 1.1% to 4.3% of the module. The tooth profile of the external tooth (12) is a convex arc shape, the chord length of the tooth profile of the external tooth (12) is 44% to 51% of the module, and the chord height is 4.5% to 5.7% of the module.

4. The gear structure with a special tooth profile according to claim 3, characterized in that, The chord angle of the tooth profile of the internal tooth (11) ranges from 13° to 25°, and the chord angle of the tooth profile of the external tooth (12) ranges from 33° to 40°.

5. The gear structure with a special tooth profile according to claim 2, characterized in that, A tooth groove (13) is provided between two adjacent tooth profiles, and the depth of the tooth groove (13) ranges from 3.4% to 6% of the module of the gear (1).

6. The gear structure with a special tooth profile according to claim 2, characterized in that, The two meshing gears (1) have the same number of teeth.

7. The gear structure with a special tooth profile according to claim 2, characterized in that, The two meshing gears (1) have different numbers of teeth.

8. The gear structure with a special tooth profile according to any one of claims 1 to 7, characterized in that, The hub of the gear (1) is circular.

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