A Design Method for Reducing Noise of Spiral Bevel Gears

Abstract

The present invention provides a method for reducing the noise of spiral bevel gears. The contact area of the spiral bevel gear pair is finely adjusted to make the contact trace of the spiral bevel gear pair deflect within a preset range. This deflection changes according to a preset law between the teeth of the pinion, such as changing according to a sine law. The change of the meshing contact trace will also cause the corresponding change of the contact area, so that the noise spectrum characteristics generated during the meshing process of the gear pair can be improved. That is, the high-frequency noise of the gear pair is reduced by the method of increasing the energy of the scattered harmonic peaks on the low-frequency sideband, effectively reducing the noise pollution and providing a new idea for gear noise control.

Description

Technical Field

[0001] The present invention relates to the technical field of gear noise reduction, and particularly relates to a noise reduction design method for spiral bevel gears. Background Art

[0002] With the continuous progress of electric vehicle technology, the motor is continuously improved in the direction of high speed, high efficiency and high peak torque. The maximum input speed of the matching reducer assembly has reached 15,000 - 20,000 RPM, and will reach 30,000 RPM in the next few years. The input speed of the reducer assembly is 3 - 10 times that of fuel vehicles. The high-frequency noise (such as howling) generated by its gear transmission system during high-speed meshing becomes the main noise source of electric vehicles, and the high-frequency noise is more harmful to people's psychology and physiology than the low-frequency noise generated by fuel vehicles. In addition, compared with fuel vehicles, electric vehicles do not have the cover of engine sound, and the noise in the reducer assembly will be more obvious, and the noise quality is even worse than that of fuel vehicles, seriously reducing the NVH (Noise, Vibration, Harshness) performance of electric vehicles.

[0003] Traditional methods for reducing the noise of the transmission system are mainly achieved by controlling the machining accuracy, installation accuracy, lubrication method, housing structure, optimization of macroscopic geometric parameters, tooth surface modification, etc. of transmission parts. Most of these methods are considered from the macroscopic structure of gears. However, the high-frequency noise generated by the gear pair at high speed is mainly generated by the microscopic tooth surface topography. Therefore, it is increasingly difficult for the current methods to achieve the purpose of suppressing high-frequency noise. In addition, the existing gear system noise control methods mainly aim to reduce the noise amplitude, and do not fully consider the influence of the noise spectrum characteristics on human psychology.

[0004] It should be noted that the above introduction of the technical background is only for the convenience of clearly and completely explaining the technical solutions of the present application and facilitating the understanding of those skilled in the art. It cannot be considered that the above technical solutions are well-known to those skilled in the art just because these solutions are described in the background art part of the present application. Summary of the Invention

[0005] The object of the present invention is: aiming at the deficiencies in the above background art, to provide a noise reduction design method for spiral bevel gears, so as to reduce the high-frequency noise of spiral bevel gears on the premise of not changing the machining accuracy.

[0006] To achieve the above object, the present invention provides a noise reduction design method for spiral bevel gears, which finely adjusts the contact area of the spiral bevel gear pair, so that the contact trace of the spiral bevel gear pair deflects within a preset range. This deflection changes according to a preset rule between the teeth of the pinion, so as to change the contact area accordingly, and improve the noise spectrum characteristics generated during the meshing process of the gear pair.

[0007] Furthermore, the deflection varies according to a sine function rule between the teeth of the pinion.

[0008] Furthermore, the change of the contact trace when the pinion rotates one week is one minimum sine period.

[0009] Furthermore, the change of the contact trace when the pinion rotates one week is two or more minimum sine periods.

[0010] Furthermore, assuming that the number of teeth of the pinion is n and the change amplitude of the contact trace is A, the angle of deflection of the k-th tooth relative to the meshing trace of the first tooth is

[0011]

[0012] At this time, the contact trace direction angle β K = β K '+ θ K , β K ' is the original contact trace direction angle.

[0013] Furthermore, the deflection varies according to a normal distribution rule between the teeth of the pinion.

[0014] Furthermore, assuming that the change amplitude of the contact trace is A, the angle of deflection of the k-th tooth relative to the meshing trace of the first tooth is

[0015]

[0016] In the formula, f(x) is the probability density of the normal distribution, and m k is the random number generated by the k-th tooth. At this time, the contact trace direction angle β K = β K '+ θ K , β K ' is the original contact trace direction angle.

[0017] The above solution of the present invention has the following beneficial effects:

[0018] The noise reduction design method provided by the present invention sets the meshing contact trace of the gear teeth to change according to a certain specific rule, such as changing according to the sine rule. The change of the meshing contact trace will also cause the corresponding change of the contact area, so as to improve the noise spectrum characteristics generated during the meshing process of the gear pair. That is, by increasing the method of dispersing the harmonic peak energy of the low-frequency sideband, the high-frequency noise of the gear pair is reduced, effectively reducing the noise pollution, and providing a new idea for gear noise control;

[0019] Other beneficial effects of the present invention will be described in detail in the subsequent specific implementation part. Brief Description of the Drawings

[0020] Figure 1In Embodiment 1 of the present invention, the sine of the deflection angle of the meshing trace of the seven-tooth pinion varies;

[0021] Figure 2 Schematic diagram of the contact trace of the working tooth surface of the seven-tooth pinion in Embodiment 1 of the present invention;

[0022] Figure 3 Schematic diagram of the rotation projection of the meshing trace of the seven-tooth pinion on one tooth surface in Embodiment 1 of the present invention;

[0023] Figure 4 Schematic flow chart of Embodiment 2 of the present invention. Detailed implementation manners

[0024] To make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention. In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0025] In the description of the present invention, for simplicity, the method or rule is depicted or described as a series of operations, the purpose of which is neither to exhaust the experimental operations nor to limit the order of the experimental operations. For example, the experimental operations can be carried out in various orders and / or simultaneously, and include other experimental operations not described again. In addition, the described steps are not all essential for the methods and algorithms described herein. Those skilled in the art can recognize and understand that these methods and algorithms can be represented as a series of unrelated states through state diagrams or items.

[0026] The present invention relates to the technical field of gear noise reduction. The existing methods for reducing the noise of the transmission system are mainly achieved by controlling the machining accuracy, installation accuracy, lubrication method, housing structure, optimization of macroscopic geometric parameters, tooth surface modification, etc. of the transmission parts. Most of these methods consider from the macroscopic structure of the gear, while the high-frequency noise generated when the gear pair rotates at high speed is mainly generated by the microscopic topography of the tooth surface. Therefore, it is increasingly difficult for the current methods to achieve the purpose of suppressing high-frequency noise. In addition, the existing gear system noise control methods mainly aim to reduce the noise amplitude and do not fully consider the influence of the noise spectrum characteristics on the human psyche. Based on this, the present invention provides a gear noise reduction method to improve the above problems.

[0027] Embodiment 1

[0028] Embodiment 1 of the present invention provides a noise reduction design method for spiral bevel gears.

[0029] Specifically, the contact area of the spiral bevel gear pair is finely adjusted to deflect the contact trace of the spiral bevel gear pair within a small range (i.e., finely adjust the contact trace direction angle). This deflection varies according to a preset law between the pinion teeth. In this embodiment, it varies according to the sine function law.

[0030] When varying according to the sine function law, it is preferably that the change of the contact trace during one rotation of the pinion is one minimum sine period. When the number of pinion teeth is large, if the change of the contact trace during one rotation of the pinion being one minimum sine period is not ideal for reducing high-frequency noise, two or more minimum positive periods can also be tried, or a larger change amplitude can be set.

[0031] Figure 1 The figure shows the change of the deflection angle of the meshing trace of a pinion with seven teeth over one sine period. 1 to 7 are the sequential numbers assigned to the pinion teeth, as Figure 2 shown. Assuming the change amplitude is A, the angle by which the kth tooth deflects the meshing trace relative to the first tooth is

[0032]

[0033] The contact trace of the working tooth surface of the seven-tooth pinion after the change is as Figure 2 shown. To facilitate showing the change of the meshing traces of the seven teeth, the meshing traces of the seven teeth after the change are rotationally projected onto the working tooth surface of tooth 1, and the corresponding tooth numbers and the rotation angle θ of the meshing trace of the corresponding tooth relative to the original trace are marked K , as Figure 3 shown. At this time, the contact trace direction angle β K = β K '+ θ K , where β K ' is the original contact trace direction angle.

[0034] The contact trace direction angle refers to the direction of the tooth surface contact area or contact spot. By presetting the contact trace direction angle and using an optimization algorithm, the optimal machine tool processing parameters and tool parameters are obtained, so as to control the direction of the contact area, and further achieve the purpose of improving the meshing performance of the gear pair.

[0035] If the change law is a non-periodic function, such as a normal distribution (or considering the t-distribution), then the period problem does not need to be considered, but a change amplitude A also needs to be preset. Taking the seven-tooth pinion as an example, seven random real numbers within a certain range (the values should not be too large) can be generated by a computer, then the angle by which the kth tooth deflects the meshing trace relative to the first tooth

[0036]

[0037] where f(x) is the probability density of the normal distribution, m kThe random number generated for the k-th tooth, and at this time the contact trace direction angle β K = β K '+ θ K , where β K ' is the original contact trace direction angle.

[0038] By using the method for precisely regulating the microscopic topological structure of the tooth surface provided in this embodiment, the meshing contact trace of the gear teeth changes according to a certain specific rule, such as changing according to the sine rule. The change in the meshing contact trace will also cause the corresponding change in the contact area, thereby improving the noise spectrum characteristics generated during the meshing process of the gear pair. That is, by increasing the energy of the scattered harmonic peaks in the low-frequency sidebands, the high-frequency noise of the gear pair is reduced, effectively reducing the noise pollution and providing a new idea for gear noise control. The noise experiment results show that: the noise amplitude can be reduced by up to 3 decibels, and the comfort level of the perceived noise is improved.

[0039] Embodiment 2:

[0040] Embodiment 2 of the present invention provides a specific design method for spiral bevel gears. As Figure 4 shown, it includes the following steps:

[0041] S1. Determine the gear pair parameters. Specifically, it includes the following sub-steps:

[0042] S11. Determine the basic design parameters of the gear pair. Determine the design parameters of the gear pair from the input speed, output speed, load, rotation direction, etc. of the gear pair. Its design parameters include module, number of teeth, offset distance, pressure angle, helix angle, tooth width, cutter head radius, shaft angle, cutting allowance, etc.

[0043] S12. Calculate the geometric parameters of the gear pair. Design the geometric parameters of the gear pair according to the gear pair design parameters: diameters of the large and small gears, tooth height, cone distance, cone angle, tooth thickness, groove width, etc.

[0044] S13. Calculate the generating gear parameters of the large gear in combination with the selected large gear cutter head parameters (including cutter head radius, tooth profile angle, tip radius of curvature, etc.). Since the gear cutters have been standardized, when machining the large gear, it is necessary to select the cutter according to the geometric parameters of the gear to be machined, and then calculate the generating gear parameters of the large gear (including curvature parameters in the tooth length and tooth height directions, position vector, unit normal vector, etc.) in combination with the selected cutter parameters.

[0045] S14. Calculate the machining parameters and curvature parameters of the large gear in combination with the meshing equation. After obtaining the generating gear parameters of the large gear, the machining parameters and curvature parameters and other tooth surface parameters of the large gear can be calculated according to the meshing equation.

[0046] S15. Calculate the tooth surface parameters of the small gear. Use the tooth surface of the large gear to calculate the position vector, unit vector, curvature parameters and other tooth surface parameters of the small gear.

[0047] S16. Calculate the machining parameters of the pinion. Based on the pinion tooth surface parameters obtained in S15, the pinion generating gear parameters can be obtained. Combining with the selected pinion machining cutter head parameters, meshing equation, etc., the pinion machining parameters can be obtained.

[0048] S2. Conduct a contact analysis on the gear pair. Establish a mathematical model of the gear pair, conduct a tooth surface contact analysis on the gear pair, and obtain the tooth surface contact area and transmission error of the gear pair under ideal conditions. The main judgment basis for the quality of the tooth surface contact area is to determine whether it meets the requirements according to the position, size, and shape of the contact area, and to judge by whether the transmission error curve is smooth and continuous. If the above conditions are met, it indicates that the design meets the expected requirements, and then proceed to the next step. If not, correct the basic design parameters, cutter head parameters of the large and small gears, and preset parameters (including contact trace deflection angle, tooth surface mismatch coefficient, contact balance coefficient, etc.).

[0049] S3. Conduct three-dimensional modeling on the gear pair. Based on the designed geometric parameters and machining parameters of the gear pair, calculate the tooth surface coordinate points and establish a three-dimensional model of the gear pair for subsequent performance simulation of the gear pair.

[0050] S4. Conduct noise prediction simulation. Conduct noise prediction simulation on the gear pair, assemble the three-dimensional model of the gear pair, and conduct noise simulation on the gear pair considering installation errors and machining errors. It is required to reduce the noise by 3 decibels or more on the original noise level, and verify whether the noise prediction simulation meets the expected requirements. If it meets, proceed to the next step. If not, correct the design parameters, cutter head parameters, and preset parameters.

[0051] It also includes S5. Conduct single-piece trial production of the gear pair for actual machining and bench testing. Conduct noise testing experiments on the test bench, with the goal of reducing the noise by 3 decibels or more on the original noise level. Check whether the noise test results meet the expected requirements. If they meet, proceed to the next step. If not, correct the design parameters, cutter head parameters, and preset parameters. After meeting the expected requirements, conduct mass production of the gear pair.

[0052] The above is the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for noise reduction design of spiral bevel gears, characterized in that, Fine-tune the contact area of the spiral bevel gear pair to deflect the contact trace of the spiral bevel gear pair within a preset range. This deflection changes according to a preset law between the teeth of the pinion, so that the contact area changes accordingly, and the noise spectrum characteristics generated during the meshing process of the gear pair are improved; The deflection changes according to the sine function law between the teeth of the pinion; Let the number of teeth of the pinion be n and the change amplitude of the contact trace be A. Then the angle of deflection of the k-th tooth relative to the meshing trace of the first tooth is ； At this time, the contact trace direction angle , is the original contact trace direction angle.

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