New energy automobile NW planetary reducer uniform load coefficient test method and system

Abstract

The invention discloses a new energy automobile NW planetary reducer uniform load coefficient test method and system, and the method comprises the steps: pasting n strain gauges at a position, close to a tooth root, of the end surface of an inner gear ring of a to-be-tested NW planetary reducer during testing, and uniformly distributing the strain gauges in the circumferential direction of the inner gear ring; marking an initial mounting position relationship between the planet gear and the strain gauge so as to enable each strain signal detected by the strain gauge to correspond to the planet gear; and testing the to-be-tested NW planetary reducer by adopting the torque rotating speed test working condition, recording the strain value of each strain gauge, and calculating the uniform load coefficient of the NW planetary reducer through the strain values of the n strain gauges. According to the method, the influence of the manufacturing error of the inner gear ring on poor uniform load can be considered, and the uniform load coefficient of the NW planetary reduction gearbox is accurately calculated.

Description

Technical Field

[0001] This invention relates to the field of planetary gear transmission technology, and in particular to a method and system for testing the load sharing coefficient of NW planetary reducers for new energy vehicles. Background Technology

[0002] New energy vehicle electric drive products are developed around the technological roadmap of high efficiency, miniaturization, and high voltage. Compared with parallel axis electric drives, coaxial electric drives are smaller and lighter, with a total weight reduction of 10-13 kg. The coaxial electric drive configuration is mainly based on the NW planetary gear configuration, which has driven domestic companies to gradually mass-produce it in recent years, and it is mostly used in mid-to-high-end models.

[0003] In planetary gear transmission systems, due to the collaborative nature of multiple gear pairs, manufacturing errors are easily amplified during meshing, ultimately leading to significant deterioration in NVH performance. In particular, phase angle deviations caused by assembly precision issues between the planet carrier and planet gears can result in uneven load distribution, further exacerbating NVH performance degradation. Therefore, a testing system and evaluation method for the load sharing coefficient of NW planetary reducers become especially important.

[0004] While existing technologies include methods for testing the load sharing coefficient of planetary gear transmissions, such as the "Method for Determining Tooth Root Stress and Load Sharing Coefficient for Planetary Gear Trains" (CN117347045A), the "Load Sharing Verification Test System for Planetary Gearbox for Tunnel Boring Machines and Method for Determining Uneven Load Coefficient of Planetary Gearbox" (CN115326389A), and the "A Method and System for Testing and Analyzing Load Sharing of Wind Turbine Gearboxes" (CN115577602A), these load sharing test methods are not applicable to NW planetary gearboxes for new energy vehicles. Furthermore, these methods cannot consider the influence of internal gear pitch error on poor load sharing, nor can they pinpoint the location of the planetary gears causing poor load sharing. Therefore, there is an urgent need to invent a method and system for testing the load sharing coefficient of NW planetary gearboxes for new energy vehicles. Summary of the Invention

[0005] To address the shortcomings of the existing technology, the technical problem to be solved by this invention is: how to provide a test method and system for the load sharing coefficient of NW planetary reducers for new energy vehicles that can accurately calculate the load sharing coefficient of NW planetary reducers, taking into account the influence of internal gear ring manufacturing errors on poor load sharing.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A method for testing the load-sharing coefficient of an NW planetary reducer for new energy vehicles includes the following steps: S1. Strain gauges are attached to the end face of the internal gear ring of the NW planetary reducer to be tested, near the tooth root. n strain gauges are evenly distributed along the circumference of the internal gear ring. S2. Mark the initial installation position relationship between the planetary gears and the strain gauges so that each strain signal detected by the strain gauges corresponds to the planetary gears; S3. The NW planetary reducer under test is tested using the torque-speed test condition, and the strain value of each strain gauge is recorded. S4. Calculate the load-sharing coefficient of the NW planetary reducer, as shown in the following formula: ; ; In the formula, The load sharing coefficient of the NW planetary reducer. The uniform load factor calculated for the strain gauge at position i is... The strain is given when the three planetary gears pass through this position.

[0007] Furthermore, for any three adjacent strain values ​​at any location, the difference between each strain value and the average strain value is calculated. The planetary gear corresponding to the strain value with the largest difference is identified as the planetary gear causing poor load distribution, as shown in the following formula: ; In the formula, For the i-th planetary gear, Let the strain be that of the i-th planetary gear. The strain is given when the three planetary gears pass through this position.

[0008] Furthermore, three strain gauges are evenly distributed along the circumference of the internal gear ring.

[0009] A load-sharing coefficient testing system for NW planetary reducers in new energy vehicles includes a bracket for mounting the NW planetary reducer, a drive motor for providing torque, a load motor for controlling speed, and a signal acquisition system. The signal acquisition system is connected to n strain gauges. During testing, the NW planetary reducer under test is mounted on the bracket. The drive motor is connected to the sun gear of the NW planetary reducer via a coupling, and the load motor is connected to the planet carrier of the NW planetary reducer via a coupling. The n strain gauges are evenly distributed circumferentially and attached to the internal gear ring of the NW planetary reducer under test near the tooth root. The load-sharing coefficient of the NW planetary reducer is calculated using the aforementioned test method.

[0010] In summary, this invention has the advantages of considering the influence of internal gear ring manufacturing errors on poor load sharing, locking the position of the planetary gears that cause poor load sharing, and accurately calculating the load sharing coefficient of the NW planetary gearbox. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the NW planetary reducer load sharing coefficient testing system; Figure 2 This describes the internal structure of the NW planetary reducer. Figure 3 This is a schematic diagram of strain data from a strain gauge; Detailed Implementation

[0012] The present invention will be further described in detail below with reference to the embodiments.

[0013] like Figures 1 to 3 As shown, a load-sharing coefficient testing system for an NW planetary reducer in a new energy vehicle includes a bracket 4. An NW planetary reducer 1 to be tested is fixedly mounted on the bracket 4. The sun gear of the NW planetary reducer is connected to a drive motor 2 for providing torque via a coupling 3. The planet carrier of the NW planetary reducer is connected to a load motor 5 for controlling speed via a coupling. Strain gauges are attached to the internal gear ring of the NW planetary reducer near the tooth root. n strain gauges are evenly distributed along the circumference of the internal gear ring. The n strain gauges are connected to a signal acquisition system 6 via wires to calculate the load-sharing coefficient and pinpoint the location of the planetary gear causing poor load sharing.

[0014] In this embodiment, n=3. For example... Figure 2 As shown, the NW planetary reducer in this embodiment includes a housing 15, an internal gear ring 14, a planet carrier 13, a first planetary gear 10, a second planetary gear 11, and a third planetary gear 12. Strain gauges include a first strain gauge 7, a second strain gauge 8, and a third strain gauge 9 attached to the internal gear ring 14, with a spatial phase difference of 120°, used to measure the strain generated at the root position of the internal gear ring when the planetary gears pass through this position. Attaching the strain gauges to three positions circumferentially on the internal gear ring allows for testing the influence of manufacturing errors on the load-sharing coefficient.

[0015] Mark the initial installation position relationship between the planetary gears and strain gauges so that each strain signal detected by the strain gauges can be correlated with a planetary gear. For example... Figure 2 As shown, the planetary gears revolve clockwise around the main shaft. The strain peak values ​​collected by the first strain gauge 7 are the first planetary gear 10, the second planetary gear 11, and the third planetary gear 12, respectively; the strain peak values ​​collected by the second strain gauge 8 are the third planetary gear 12, the first planetary gear 10, and the second planetary gear 11, respectively; and the strain peak values ​​collected by the second strain gauge 9 are the second planetary gear 11, the third planetary gear 12, and the first planetary gear 10, respectively.

[0016] The drive motor outputs a torque of 50 Nm, and the load motor provides a test speed of 10 rpm. The strain values ​​of strain gauges at three locations are recorded. Each time the planetary gear passes a strain gauge location, an impact signal is generated, indicating the maximum micro-strain value measured by the strain gauge. For every revolution of the output shaft, each planetary gear passes that location three times, resulting in three peak values ​​at each location. Figure 3 As shown in the figure, from top to bottom, the strain signal waveforms collected by the first strain gauge 7, the second strain gauge 8, and the third strain gauge 9 are respectively. The strains of the first planetary gear 10, the second planetary gear 11, and the third planetary gear 12 collected by the first strain gauge 7 are -46.5μE, -41μE, and -46μE, respectively. The strains of the first planetary gear 10, the second planetary gear 11, and the third planetary gear 12 collected by the second strain gauge 8 are -75.5μE, -72μE, and -74μE, respectively. The strains of the first planetary gear 10, the second planetary gear 11, and the third planetary gear 12 collected by the third strain gauge 9 are -64.8μE, -60μE, and -64μE, respectively.

[0017] The load-sharing coefficient of the NW planetary reducer is calculated as follows: ; ; In the formula, The load sharing coefficient of the NW planetary reducer. The uniform load factor calculated for the strain gauge at position i is... These represent the strains of the first planetary gear 10, the second planetary gear 11, and the third planetary gear 12 as they pass through this position. The maximum value, It is the minimum value.

[0018] The load-averaging factor at the first strain gauge 7 is 1.12, at the second strain gauge 8 it is 1.05, at the third strain gauge 9 it is 1.07, and the average load-averaging factor is 1.08. The difference in load-averaging factor at each location is due to the different tooth pitch errors at different positions of the gear ring.

[0019] The location of the planetary gear causing poor load distribution is locked. Based on the strain values ​​of the first planetary gear 10, the second planetary gear 11, and the third planetary gear 12 when they pass through any strain gauge location, the planetary gear with the largest change is identified as the root cause of poor load distribution.

[0020] For example, at the location of the first strain gauge 7, the strains of the first planetary gear 10, the second planetary gear 11, and the third planetary gear 12 are -46.5μE, -41μE, and -46μE, respectively, with an average strain value of -44.5μE. The differences between the three strain values ​​and the average strain value are 2μE, -3.5μE, and 1.5μE, respectively. Therefore, the planetary gear with the largest change is the second planetary gear 11.

[0021] At the location of the second strain gauge 8, the strains of the first planetary gear 10, the second planetary gear 11, and the third planetary gear 12 are -75.5μE, -72μE, and -74μE, respectively, with an average strain value of -73.8μE. The differences between the three strain values ​​and the average strain value are 1.7μE, -1.8μE, and 0.2μE, respectively. Therefore, the planetary gear with the largest change is the second planetary gear 11.

[0022] At the location of the third strain gauge 8, the strains of the first planetary gear 10, the second planetary gear 11, and the third planetary gear 12 are -64.8μE, -60μE, and -64μE, respectively, with an average strain value of -62.9μE. The differences between the three strain values ​​and the average strain value are 1.9μE, -2.9μE, and 1.1μE, respectively. Therefore, the planetary gear with the largest change is the second planetary gear 11.

[0023] Regardless of the location of the strain gauge, the strain value of the second planetary gear 11 differs significantly from that of the other two planetary gears. Therefore, the second planetary gear 11 is identified as the root cause of poor load sharing and should be given special attention.

[0024] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for testing the load-sharing coefficient of an NW planetary reducer for new energy vehicles, characterized in that, Includes the following steps: S1. Strain gauges are attached to the end face of the internal gear ring of the NW planetary reducer to be tested, near the tooth root. n strain gauges are evenly distributed along the circumference of the internal gear ring. S2. Mark the initial installation position relationship between the planetary gears and the strain gauges so that each strain signal detected by the strain gauges corresponds to the planetary gears; S3. The NW planetary reducer under test is tested using the torque-speed test condition, and the strain value of each strain gauge is recorded. S4. Calculate the load-sharing coefficient of the NW planetary reducer, as shown in the following formula: ； ； In the formula, The load sharing coefficient of the NW planetary reducer. The uniform load factor calculated for the strain gauge at position i is... The strain is given when the three planetary gears pass through this position.

2. The method for testing the load-sharing coefficient of NW planetary reducers for new energy vehicles as described in claim 1, characterized in that, For any three adjacent strain values ​​at any location, calculate the difference between each strain value and the average strain value. Identify the planetary gear corresponding to the strain value with the largest difference as the planetary gear causing poor load distribution, as shown in the following formula: ； In the formula, For the i-th planetary gear, Let the strain be that of the i-th planetary gear. The strain is given when the three planetary gears pass through this position.

3. The method for testing the load-sharing coefficient of NW planetary reducers for new energy vehicles as described in claim 1, characterized in that, Three strain gauges are evenly distributed along the circumference of the internal gear ring.

4. A load-sharing coefficient testing system for NW planetary reducers in new energy vehicles, characterized in that, The test includes a bracket (4) for mounting the NW planetary reducer, a drive motor (2) for providing torque, a load motor (5) for controlling the rotational speed, and a signal acquisition system (6), on which n strain gauges are connected. During testing, the NW planetary reducer to be tested is mounted on the bracket (4), the drive motor (2) is connected to the sun gear of the NW planetary reducer via a coupling (3), the load motor (5) is connected to the planet carrier of the NW planetary reducer via a coupling, and the n strain gauges are evenly distributed circumferentially and pasted on the internal gear ring of the NW planetary reducer to be tested near the tooth root. The load-equalizing coefficient of the NW planetary reducer is calculated using the load-equalizing coefficient test method for NW planetary reducers in new energy vehicles as described in claim 1.

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