Backlash suppression structure for gear with gradually varied axial tooth thickness

Abstract

The utility model discloses an axial tooth thickness gradual change gear and a backlash suppression structure, and belongs to the field of machinery. The tooth thickness of the cylindrical surface characteristic gear is gradually changed, that is, the corresponding tooth thickness on each cross section is different and is monotonically gradually changed. When the two gears are used in a matched mode, the changes of the tooth thicknesses of the cross sections of the two gears are opposite, and the tooth contact backlash can be changed through axial displacement of one gear. Gaps between the teeth can be increased when the teeth are far away from each other, gaps between the teeth can be reduced when the teeth are close to each other, and even zero-gap contact is achieved at proper positions; tooth clearance suppression has three structures, namely an end face gasket increasing and decreasing structure, an end piece abrasion compensation structure and a taper abrasion compensation structure. The continuous high-precision operation of the gear system can be ensured; the device can be widely applied to the mechanical industry.

Description

Technical Field

[0001] This invention belongs to the field of mechanical technology, specifically a kind of Background Technology

[0002] Overview of the history of gear development:

[0003] As early as 1694, the French scholar Philippe de la Hire first proposed that the involute could be used as a tooth profile curve. In 1733, the Frenchman M. Camus proposed that the common normal of the tooth contact point must pass through the node on the center line. When an auxiliary instantaneous center line rolls purely along the instantaneous center lines (pitch circles) of the large and small gears respectively, the two tooth profile curves formed by the auxiliary tooth profiles fixed to the auxiliary instantaneous center line on the large and small gears are conjugate to each other. This is Camus' theorem. It considers the meshing state of the two tooth surfaces and clearly establishes the modern concept of the contact point trajectory. In 1765, the Swiss L. Euler proposed the mathematical foundation for the analytical study of involute tooth profiles, clarifying the relationship between the radius of curvature and the center of curvature of the tooth profile curves of a pair of meshing gears. Later, Savary further completed this method, which became the Eu-Let-Savary equation. ROTEFT WULLS made significant contributions to the application of involute tooth profiles, proposing that involute gears maintain a constant angular velocity ratio despite changes in center distance. In 1873, German engineer Hoppé proposed the involute tooth profile for gears with different numbers of teeth under varying pressure angles, thus laying the foundation for modern modified gears. With the development of production, the smoothness of gear operation became increasingly important. In 1674, Danish astronomer Rømer first proposed using an epicycloid as the tooth profile curve to obtain gears with smooth operation. During the Industrial Revolution in the 18th century, gear technology developed rapidly, and extensive research was conducted on gears. In 1733, French mathematician Camille published the fundamental law of tooth profile meshing; in 1765, Swiss mathematician Euler suggested using an involute as the tooth profile curve.

[0004] In the late 19th century, the emergence of the generating gear cutting method and specialized machine tools and cutting tools using this principle provided more complete means for gear machining, and the involute tooth profile showed great superiority. During gear cutting, simply moving the cutting tool slightly from its normal meshing position allows for the cutting of corresponding modified gears on a machine tool using standard cutting tools. In 1908, the Swiss company MAAG researched the modification method and manufactured a generating gear shaper. Later, the British BSS, the American AGMA, and the German DIN successively proposed various calculation methods for gear modification. To improve the service life and reduce the size of power transmission gears, in addition to improvements in materials, heat treatment, and structure, gears with circular arc tooth profiles were developed. In 1907, the Englishman Frank Humphurst first published the circular arc tooth profile. In 1926, the Swiss Eruest Wildhaber obtained a patent for a helical gear with a normal circular arc tooth profile. In 1955, the Soviet Union's M. L. Novikov completed practical research on circular arc toothed gears and was awarded the Order of Lenin. In 1970, R. M. STUDER, an engineer at the British company ROLH-ROYCE, obtained a US patent for double circular arc gears. This type of gear is now receiving increasing attention and has proven to be very effective in production.

[0005] In 1899, Laschet first implemented the modified gear design. Modified gears not only avoid tooth undercut but also adjust the center distance and improve the gear's load-carrying capacity. In 1923, Wildhaber in the United States first proposed gears with circular arc tooth profiles. In 1955, Sunovikov conducted in-depth research on circular arc gears, which were then applied to production. These gears have high load-carrying capacity and efficiency, but they are not as easy to manufacture as involute gears and require further improvement. The hobbing machine and gear shaping machine, which appeared in the 19th century, solved the problem of mass-producing high-precision gears. In 1900, Pflötter equipped the hobbing machine with a differential device, enabling the machining of helical gears on the hobbing machine. From then on, gear hobbing became widespread, and the generating method for gear machining gained overwhelming dominance, with involute gears becoming the most widely used gears.

[0006] Existing methods for suppressing gear tooth backlash:

[0007] Gear backlash refers to the distance between the non-working surfaces of a pair of meshing gears along the normal direction.

[0008] Generally, gear backlash should be as small as possible while ensuring normal use. It is set during manufacturing based on the required precision level of the gears. Using high-precision machining equipment and achieving higher levels of machining and assembly processes results in smaller backlash; this primarily improves the precision of the transmission process and the control precision of the driven device, especially in high-end machine tool modules. However, there are other reasons why gear drives require backlash: a pair of meshing gears must have backlash to compensate for manufacturing and installation tolerances, elastic deformation under transmission loads, and deformation due to temperature effects. It also allows for the storage of a certain amount of lubricating oil to improve the lubrication of the gear surfaces.

[0009] Cylindrical gears:

[0010] *Center distance adjustment: By changing the center distance, the minimum limiting side clearance can be obtained.

[0011] *Misalignment adjustment method: By changing the misalignment displacement of the double-plate thin gear, the minimum limiting backlash can be obtained;

[0012] Helical gear situation:

[0013] *Center distance adjustment: By changing the center distance, the minimum limiting side clearance can be obtained.

[0014] *Axial shim adjustment: Add axial shims to achieve minimum clearance.

[0015] However, the industry currently lacks a way to automatically eliminate wear gaps that occur during use.

[0016] Besides adjusting the shaft spacing of the two gears, the method of eliminating backlash in double-plate thin gears involves: Backlash elimination gear transmission refers to eliminating tooth backlash in gear transmission. This method makes the driven gear of a pair of gears into two thin plates, one fixed to the shaft and the other fitted onto the hub of the same gear. Each thin gear plate has lugs, and a tension spring is hooked at one end to the lug and the other end to a fixing screw. A nut is used to adjust the extension length of the screw and to lock it in place. This structure utilizes the tension of the tension spring to ensure that the left side of the tooth of one thin gear and the right side of the tooth of the other thin gear are tightly pressed against the left and right sides of the tooth groove of the driving gear, respectively. This staggered tooth structure eliminates tooth backlash, preventing backlash error in the reverse direction. The role of the tension spring in the backlash elimination structure of double-plate thin gears is to utilize the tension force generated after the spring deforms, ensuring that the driving and driven gears are tightly pressed against each other in both forward and reverse directions. Because the position of the backlash elimination tension spring in the structure is confined to a ring-shaped area, and the parts fixing the tension spring are also located within this ring-shaped area, the above requirements must be met in the design.

[0017] Throughout the entire process of using a gear system, various clearances will wear out and become larger, so the requirements for materials, processes, and gear processing are very strict, and the price difference between gears of different qualities is also very large. Summary of the Invention

[0018] The purpose of this invention:

[0019] In order to automatically eliminate the wear clearance of gears during use, so as to maintain high-precision operation for a long time.

[0020] The feature of this invention is that it employs the principle of compensation.

[0021] Key technologies of this invention:

[0022] The mechanism of axial relative movement is adopted, provided that the side surface of the tooth is changed so that the normal of the surface is not perpendicular to the gear axis, and the side surface becomes part of the conical surface.

[0023] Specific details of the invention:

[0024] The axial tooth thickness gradually varying gear structure includes: tooth tips, tooth roots, and tooth flanks symmetrically distributed around the axis, characteristic of cylindrical gears; its key feature is that the tooth thickness varies on each cross-section (parallel to the end face), exhibiting a monotonically gradual change, with the maximum and minimum tooth thicknesses obtained on the two end faces. In paired use, the tooth thicknesses of the two gears change in opposite directions. Axial displacement of one gear alters the tooth contact clearance (commonly known as backlash); moving them away increases the tooth clearance, while moving them closer decreases it, and in suitable positions, even achieves zero-clearance contact.

[0025] There are three types of backlash suppression structures: adding or removing end face gaskets, end plate wear compensation structure, and taper wear compensation structure.

[0026] *End face shims are added to the structure: As gear systems wear gradually with continuous use, axial displacement of the gear can be achieved by increasing or decreasing the number of shims at the two end faces of the gear, or by changing the shim thickness, thereby reducing backlash.

[0027] *End plate wear compensation structure: Springs and compensation plates are installed at two end faces of at least one gear. The springs apply a pushing force to the end face of the gear, while the other end face of the gear presses against the compensation plate. The dynamic friction generated by rotation causes the compensation plate to wear. The material of the compensation plate is selected so that its wear rate can compensate for the wear rate between the teeth of the two gears. As the axial tooth thickness gradually decreases, the backlash between the two gears is reduced, thus ensuring transmission accuracy.

[0028] * Tapered wear compensation structure: At least one gear has a tapered inner bore, and the corresponding shaft is a tapered shaft; a spring applies a thrust to the end face of the gear, which acts on the inner wall of the tapered inner bore; as wear occurs, the gear will have axial displacement; the wear of the tapered inner bore can just compensate for the wear between the teeth of the two gears; the backlash between the two gears is reduced by the gradual axial downward movement of the gear with progressively thicker axial teeth, thus ensuring transmission accuracy.

[0029] Furthermore, the spring is a thrust spring, a carbon sheet, or a non-metallic elastic material.

[0030] *The foregoing describes the basic principles and main features of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

[0031] The beneficial effects of this invention are:

[0032] With its compact structure, the gear system maintains high-precision transmission despite a slight decrease in transmission efficiency and an extended service life, making it a promising option for the market. Attached Figure Description

[0033] The present invention will be further described below with reference to the accompanying drawings and preferred embodiments:

[0034] Figure 1 Schematic diagram of an axially variable tooth thickness gear structure;

[0035] Figure 2 Schematic diagram of end piece wear compensation structure

[0036] Figure 3 Schematic diagram of tapered wear compensation structure;

[0037] Label Explanation:

[0038] 1. Axial tooth thickness gradually changing gear

[0039] 1-1 Tooth Tip

[0040] 1-2 tooth roots

[0041] 1-3 Tooth flanks

[0042] 1-4 end faces

[0043] 1-5 inner holes

[0044] 1-6 teeth thickness 1

[0045] 1-7 tooth thickness 2

[0046] 2. Axis 1

[0047] 3. Axis 2

[0048] 4. Tapered shaft

[0049] 5. Shrapnel

[0050] 6. Compensation ring

[0051] 8. Axial tooth thickness gradually changing gear A

[0052] 9. Axial tooth thickness gradually changing gear B

[0053] 10. Wear-resistant compensation ring

[0054] 11. Structural support components Detailed Implementation

[0055] like Figure 1 As shown:

[0056] It is a typical axial tooth thickness gradient gear (1) with the axes of the two gears parallel, namely: axis 1 (2) and axis 2 (3); the upper left is a front view, with the inner hole (1-5) and end face (1-4) facing the viewer, and the upper right is an enlarged view of the tooth details, with the tooth tip (1-1), tooth root (1-2) and tooth side (1-3) clearly visible; the difference from conventional cylindrical gears is that the tooth thickness corresponding to the cross section (the cross section parallel to the end face) of this axial tooth thickness gradient gear is different, presenting a monotonically gradual state, and obtaining the maximum and minimum tooth thickness on the two end faces: as shown in tooth thickness 1 (1-6) and tooth thickness 2 (1-7).

[0057] When in use, the two gears are placed in opposite directions, meaning that the tooth thickness at the cross-section along the axis changes in opposite ways. In the right position, this ensures that the teeth of the two gears make contact with zero clearance. At the same time, the relative upward movement of the right gear will increase the tooth clearance, while the downward movement will decrease the tooth clearance, or even bring them into direct contact.

[0058] like Figure 2 As shown:

[0059] The end plate wear compensation structure, under the support of the structural support component (11), allows the axial tooth thickness progressive gear A (8) and axial tooth thickness progressive gear B (9) to mesh with each other under the constraint of the shaft. The left gear limits the axial displacement, while the right gear, pushed by the spring plate (5) against the end face of the axial tooth thickness progressive gear B (9), causes the axial tooth thickness progressive gear B (9) to apply pressure to the compensation ring (6). The selection of the compensation ring (6) is just enough to make its wear rate compensate for the wear rate of the teeth between the two gears; that is, as the axial tooth thickness progressive gear B (9) gradually moves axially downward, the gap between the two gears gradually decreases, thereby ensuring the transmission accuracy between the gears.

[0060] The worn compensation ring (10) is an overall view of the compensation ring (6).

[0061] like Figure 3 As shown:

[0062] The tapered wear compensation structure is expressed, and Figure 2 The basic structure is the same, the difference is that the shaft of the right gear is a tapered shaft (4), and the inner hole of the gear is also a tapered inner hole; by using the wear of the tapered shaft (4) and the tapered inner hole of the gear, the right gear is gradually moved axially downward, so as to reduce the tooth gap.

Claims

1. A side clearance suppression construction for an axially tooth-thickness- varying gearwheel, characterized by: There are three types of structures: end face gasket addition / reduction, end piece wear compensation structure, and taper wear compensation structure; End plate wear compensation structure: Springs and compensation plates are installed on two end faces of at least one gear. The springs apply a pushing force to the end face of the gear, while the other end face of the gear presses against the compensation plate. The dynamic friction generated by rotation causes the compensation plate to wear. The material of the compensation plate is selected so that its wear rate can compensate for the wear rate between the teeth of the two gears. As the axial tooth thickness gradually decreases, the backlash between the two gears is reduced, thus ensuring transmission accuracy. Tapered wear compensation structure: At least one gear has a tapered inner hole, and the corresponding shaft is a tapered shaft; a spring applies a thrust to the end face of the gear, and this thrust acts on the inner wall of the tapered inner hole; as wear occurs, the gear will produce axial displacement; and the wear of the tapered inner hole can just compensate for the wear between the teeth of the two gears; the backlash between the two gears is reduced by the gradual axial downward movement of the gear with axial tooth thickness gradient, thus ensuring transmission accuracy.

2. A side clearance suppressing structure of an axially tooth-thickness- varying gear according to claim 1, characterized in that The spring is a thrust spring, a spring sheet, or a non-metallic elastic material.

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