A motor assembly method for controlling NVH of a rear drive axle

Abstract

The present application provides a motor assembly method for controlling NVH of a rear drive axle, and relates to the technical field of motor assembly. The present invention adopts a flexible assembly method, which can effectively reduce the strong impact of the mating stop of the drive motor M and the mating stop of the rear axle main reducer L, as well as the spline collision and radial force between the output shaft of the drive motor M and the input shaft of the rear axle main reducer L, to ensure that the initial assembly state is in a good position; after the flexible assembly, the hook is removed, and the drive motor M is only subjected to the vertical downward force in the direction of its own deadweight, and is not subjected to the vertical upward pulling force of the hook, which lays a good foundation for the subsequent tightening sequence of the fixing bolts, reduces the vertical upward pulling force applied to the drive motor M by the hook during the tightening process of the fixing bolts, thereby reducing the upward deviation trend of the output shaft of the drive motor M.

Description

Technical Field

[0001] The present invention relates to the technical field of motor assembly, and in particular to a motor assembly method for controlling NVH of a rear drive axle. Background Art

[0002] In recent years, automobile OEMs have vigorously developed electric drive systems. As a highly integrated product of the current drive motor, main reducer assembly, and rear drive axle, the electric drive axle has been widely used in pure electric commercial vehicles due to its advantages such as low development difficulty, low manufacturing cost, simple structure, and small space occupation. Since pure electric vehicles have no engine noise mask and no suspension as a buffer, the NVH performance of the electric drive axle is poor, which is a major pain point complained by current OEMs and customers. Among them, the roaring problem in the NVH of coaxial / parallel axis electric drive axles has not been completely solved so far. The roaring noise is mainly 1st order, and there are 2nd, 3rd, 4th, 5th and 6th order harmonic frequencies. The fundamental reason is that the motor output shaft and the main reducer input shaft are too poorly aligned during the transmission process. With market demand, the maximum speed of the motor is constantly increasing, but the higher the motor speed, the more obvious the roaring noise will be. In order to solve the fundamental cause of this noise, in addition to the manufacturing accuracy of parts, the coaxiality of the rotating shaft, the rotational imbalance, the side clearance of the spline of the motor output shaft and the main reducer input shaft, etc., the more critical thing is the assembly process of the motor to the rear drive axle assembly.

[0003] In the prior art, in order to solve the roaring noise problem, it is proposed to use a tool to erect the rear drive axle and then install the motor vertically on the main reducer. This method can achieve optimization, but for mass production, it is not only time-consuming and slows down the production rhythm, but also has certain safety issues. Therefore, we have made improvements to this and proposed a motor assembly method for controlling the NVH of the rear drive axle. Summary of the invention

[0004] The purpose of the present invention is to solve the existing roaring noise problem caused by poor alignment between the motor output shaft and the main reducer input shaft during the transmission operation.

[0005] In order to achieve the above-mentioned purpose of the invention, the present invention provides a motor assembly method for controlling the NVH of a rear drive axle to improve the above-mentioned problem.

[0006] The specific application is as follows:

[0007] A motor assembly method for controlling NVH of a rear drive axle, comprising:

[0008] S1. Flexible assembly: Place the rear drive axle assembly on the fixed fixture, lift the drive motor with a hook, move it smoothly to the rear drive axle assembly, slowly adjust the posture, gently push the spline hole of the drive motor into the spline input shaft of the rear axle main reducer, make the mounting surfaces of the two fit together, and remove the hook;

[0009] S2. Pre-tighten the motor. According to the placement of the drive motor on the fixed workbench, apply thread locker to the fixing bolts and screw them into the threaded holes on the drive motor and the rear axle main reducer by hand to pre-tighten the fixing bolts.

[0010] S3. Tighten the motor. According to the placement of the drive motor on the fixed workbench, tighten the fixing bolts to the specified torque in the pre-tightening sequence;

[0011] S4. Pre-tighten the motor bracket: Apply thread locker to the fixing bolts and screw them into the threaded holes on the drive motor and the motor bracket, as well as the threaded holes between the motor bracket and the rear drive axle assembly by hand. Pre-tighten the fixing bolts connecting the motor bracket to the drive motor first according to the diagonal principle, and then pre-tighten the fixing bolts connecting the motor bracket to the rear drive axle assembly;

[0012] S5. Tighten the motor bracket: Tighten the fixing bolts to the specified torque in the pre-tightening sequence.

[0013] As a preferred technical solution of the present application, the pre-tightening torque of the fixing bolt in step S2 is performed at 30% of the prescribed torque.

[0014] As a preferred technical solution of the present application, the pre-tightening sequence in step S2 is: first from top to bottom, then from left to right or from right to left, and finally pre-tightening diagonally downward.

[0015] As the preferred technical solution of the present application, there are eight fixing bolts between the drive motor and the rear axle main reducer, of which six fixing bolts are located on the front of the rear axle main reducer, and the six fixing bolts are A, B, C, D, E, and F respectively; the other two fixing bolts are located on the back of the rear axle main reducer, and the two fixing bolts are G and H respectively.

[0016] As a preferred technical solution of the present application, when the drive motor is located on the front horizontal side of the rear drive axle assembly, the fixing bolts are pre-tightened in the order of B, F, D, G, C, H, A, and E.

[0017] As a preferred technical solution of the present application, the drive motor is located above the rear drive axle assembly and the fixing bolts are pre-tightened in the order of D, G, B, F, C, H, E, and A.

[0018] As a preferred technical solution of the present application, the pre-tightening torque of the fixing bolt in step S4 is performed at 30% of the prescribed torque.

[0019] As a preferred technical solution of the present application, the number of fixing bolts between the driving motor and the tightening motor bracket is six, and the six fixing bolts are O, P, Q, R, S, and T.

[0020] As the preferred technical solution of the present application, the pre-tightening order of the fixing bolts O, P, Q, R, S, T is O, S, P, T, Q, N.

[0021] As a preferred technical solution of the present application, the fixed tooling is used to support the rear drive axle assembly.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] In the scheme of this application:

[0024] 1. The present invention adopts a flexible assembly method, which can effectively reduce the strong impact of the matching stop of the drive motor M and the matching stop of the rear axle final reducer L, as well as the spline impact and radial force of the output shaft of the drive motor M and the input shaft of the rear axle final reducer L, ensuring that the initial assembly state is in a good position;

[0025] 2. After flexible assembly, remove the hook. The drive motor M is only subject to the vertical downward force in the direction of its own weight, and is not subject to the vertical upward pulling force of the hook. This lays a good foundation for the subsequent tightening sequence of the fixing bolts, reduces the vertical upward pulling force applied by the hook to the drive motor M during the tightening process of the fixing bolts, and thus reduces the upward deviation trend of the output shaft of the drive motor M;

[0026] 3. The fixing bolts on both sides of the drive motor M are pre-tightened before tightening, which can make the drive motor M fit well with the mating surface of the rear axle final reducer L, ensure the flatness of the fit, thereby ensuring the alignment of the output shaft of the drive motor M and the input shaft of the rear axle final reducer L, and reducing the assembly deviation caused by tightening the fixing bolts at one time;

[0027] 4. The order of pre-tightening and tightening the fixing bolts is based on the principle of "first from top to bottom, then from left to right or from right to left, and finally pre-tightening diagonally downward". From top to bottom, the offset caused by the deadweight of the drive motor M can be eliminated first, and then from left to right or from right to left, it plays a circumferential positioning role, and finally the order of pre-tightening and tightening diagonally downward allows the drive motor M to be in a very good assembly position, thereby ensuring the alignment of the output shaft of the drive motor M and the input shaft of the rear axle final reducer L. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic diagram of the structure of the fixed workbench provided in this application supporting the rear drive axle assembly;

[0029] Figure 2 A schematic diagram of the structure of the rear drive axle assembly provided for this application;

[0030] Figure 3 A structural schematic diagram of the rear drive axle assembly provided in this application from another perspective;

[0031] Figure 4 A schematic diagram of the three-dimensional structure of the rear drive axle assembly provided in this application. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0033] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features and technical solutions in the embodiments may be combined with each other.

[0034] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0035] For ease of understanding, this application uses J to represent fixed tooling, K to represent rear drive axle assembly, L to represent rear axle final reducer, M to represent drive motor, and N to represent motor bracket, and they are marked in the figures;

[0036] Example 1, please refer to Figure 1-Figure 4 , a motor assembly method for controlling NVH of a rear drive axle, comprising:

[0037] S1. Flexible assembly. Place the rear drive axle assembly K on the fixed fixture J, lift the drive motor M with a hook, and move it smoothly to the rear drive axle assembly K. Slowly adjust the posture, gently push the spline hole of the drive motor M into the spline input shaft of the rear axle main reducer L, so that the mounting surfaces of the two fit together, and remove the hook. The flexible assembly method can effectively reduce the strong impact of the matching stop of the drive motor M and the matching stop of the rear axle main reducer L, as well as the spline impact and radial force of the output shaft of the drive motor M and the input shaft of the rear axle main reducer L, so as to ensure that the initial assembly state is in a good position. After the flexible assembly, remove the hook. The drive motor M is only subjected to the vertical downward force in the direction of its own deadweight, and is not subjected to the vertical upward pulling force of the hook, which lays a good foundation for the subsequent tightening sequence of the fixing bolts, reduces the vertical upward pulling force applied to the drive motor M by the hook during the tightening process of the fixing bolts, and thus reduces the upward deviation trend of the output shaft of the drive motor M;

[0038] S2. Pre-tighten the motor. According to the placement position of the drive motor M on the fixed workbench J, apply thread locking agent to the fixing bolts and then manually screw them into the threaded holes on the drive motor M and the rear axle main reducer L to pre-tighten the fixing bolts. Pre-tightening the drive motor M can preliminarily fix the relative position of the drive motor M and the rear axle main reducer L, reduce the relative displacement between the two in subsequent operations, create conditions for accurately tightening the fixing bolts, help ensure the stability and consistency of the assembly, and reduce the loosening or dislocation of parts caused by not pre-tightening. Applying thread locking agent can enhance the reliability of threaded connection, reduce the loosening of fixing bolts during use, and reduce the vibration and noise caused by loose bolts.

[0039] S3, tighten the motor, according to the placement position of the drive motor M on the fixed workbench J, tighten the fixing bolts to the specified torque in the pre-tightening sequence;

[0040] S4. Pretighten the motor bracket N: Apply thread locking agent to the fixing bolts and screw them into the threaded holes on the drive motor M and the motor bracket N, as well as the threaded holes between the motor bracket N and the rear drive axle assembly K by hand. Pretighten the fixing bolts connecting the motor bracket N to the drive motor M according to the diagonal principle, and then pretighten the fixing bolts connecting the motor bracket N to the rear drive axle assembly K. Pretightening the motor bracket N can enhance the connection stability between the drive motor M and the motor bracket N, as well as between the motor bracket N and the rear drive axle assembly K. Pretightening according to the diagonal principle can make the force on the connection surface more uniform, reduce the warping or deformation of parts caused by unilateral pretightening, ensure the installation accuracy of the drive motor M on the motor bracket N, and reduce the transmission of the vibration of the drive motor M to the rear drive axle assembly K caused by improper installation of the motor bracket N;

[0041] S5. Tighten the motor bracket N: Tighten the fixing bolts to the specified torque in the pre-tightening sequence to form a reliable rigid connection between the motor bracket N, the drive motor M and the rear drive axle assembly K, which can effectively bear the various forces generated by the drive motor M when it is working, reduce the displacement or shaking of the drive motor M during operation, and reduce the vibration and noise of the rear drive axle caused by the instability of the drive motor M.

[0042] Embodiment 2 further optimizes the motor assembly method for controlling the NVH of the rear drive axle provided in Embodiment 1. Specifically, the pre-tightening torque of the fixing bolts in step S2 is performed at 30% of the prescribed torque. The pre-tightening torque of 30% of the prescribed torque can provide a certain tightening force to maintain the relative position of the parts during the pre-tightening stage, and will not cause uneven force on the fixing bolts during the subsequent tightening process due to excessive pre-tightening force. In this way, the tightening process of the fixing bolts can be better controlled, so that the connection between the drive motor M and the rear axle final reducer L gradually reaches an ideal state, reducing the assembly error caused by improper pre-tightening.

[0043] Further, such as Figure 4As shown, the pre-tightening sequence in step S2 is: first from top to bottom, then from left to right or from right to left, and finally pre-tightening diagonally downward. From top to bottom, the offset caused by the deadweight of the drive motor M can be eliminated first, and then from left to right or from right to left, it plays a circumferential positioning role. Finally, the pre-tightening and tightening sequence of diagonally downward can make the drive motor M finally in a very good assembly position, thereby ensuring the alignment of the output shaft of the drive motor M and the input shaft of the rear axle final reducer L.

[0044] Further, such as Figure 4 As shown, there are eight fixing bolts between the drive motor M and the rear axle final reducer L, of which six fixing bolts are located on the front of the rear axle final reducer L. The six fixing bolts are A, B, C, D, E, and F, respectively. Figure 2 The other two fixing bolts are located on the back of the rear axle main reducer L, and the two fixing bolts are G and H respectively.

[0045] Further, such as Figure 2 As shown, when the drive motor M is located at the horizontal side of the front of the rear drive axle assembly K, the fixing bolts are pre-tightened in the order of B, F, D, G, C, H, A, and E, so that each fixing bolt works in sequence during the pre-tightening process, which better adapts to the force characteristics of the drive motor M at this position, so that the connection between the drive motor M and the rear axle final reducer L gradually reaches a tight and uniform state, reducing loose connection, deformation or stress concentration caused by unreasonable pre-tightening sequence, ensuring the stability and reliability of the rear drive axle assembly K during vehicle driving, and reducing noise and vibration caused by assembly factors.

[0046] Furthermore, when the drive motor M is located above the rear drive axle assembly K, the fixing bolts are pre-tightened in the order of D, G, B, F, C, H, E, and A.

[0047] Embodiment 3 further optimizes the motor assembly method for controlling the NVH of the rear drive axle provided in Embodiment 1 or 2. Specifically, the pre-tightening torque of the fixing bolts in step S4 is performed at 30% of the specified torque, which is similar to the pre-tightening of the drive motor M. It can provide appropriate fastening force to prevent relative displacement of parts during initial fixation, and avoid problems such as uneven force on the fixing bolts, deformation of the motor bracket N, or poor connection between the drive motor M and the motor bracket N caused by excessive pre-tightening force during the subsequent tightening process. This helps to improve the accuracy and stability of the motor bracket installation and reduce the transmission of the drive motor M vibration caused by the motor bracket N installation problem to the rear drive axle assembly K.

[0048] Further, such as Figure 3 and Figure 4As shown, there are six fixing bolts between the driving motor M and the tightening motor bracket N, and the six fixing bolts are O, P, Q, R, S, and T.

[0049] Furthermore, the pre-tightening sequence of the fixing bolts O, P, Q, R, S, T is O, S, P, T, Q, N.

[0050] Furthermore, the fixed fixture J is used to support the rear drive axle assembly K, and the fixed fixture J provides a stable supporting platform for the rear drive axle assembly K.

[0051] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0052] Obviously, the embodiments described above are only some embodiments of the present invention, rather than all embodiments. The preferred embodiments of the present invention are given in the accompanying drawings, but they do not limit the patent scope of the present invention. The present invention can be implemented in many different forms. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive. Although the present invention has been described in detail with reference to the aforementioned embodiments, for those skilled in the art, it is still possible to modify the technical solutions recorded in the aforementioned specific implementation methods, or to replace some of the technical features therein with equivalents. Any equivalent structure made using the contents of the specification and drawings of the present invention, directly or indirectly used in other related technical fields, is also within the scope of patent protection of the present invention.

Claims

1. A motor assembly method for controlling NVH of a rear drive axle, characterized in that: include: S1. Flexible assembly: Place the rear drive axle assembly on the fixed fixture, lift the drive motor with a hook, move it smoothly to the rear drive axle assembly, slowly adjust the posture, gently push the spline hole of the drive motor into the spline input shaft of the rear axle main reducer, make the mounting surfaces of the two fit together, and remove the hook; S2. Pre-tighten the motor. According to the placement of the drive motor on the fixed workbench, apply thread locker to the fixing bolts and screw them into the threaded holes on the drive motor and the rear axle main reducer by hand to pre-tighten the fixing bolts. S3. Tighten the motor. According to the placement of the drive motor on the fixed workbench, tighten the fixing bolts to the specified torque in the pre-tightening sequence; S4. Pre-tighten the motor bracket: Apply thread locker to the fixing bolts and screw them into the threaded holes on the drive motor and the motor bracket, as well as the threaded holes between the motor bracket and the rear drive axle assembly by hand. Pre-tighten the fixing bolts connecting the motor bracket to the drive motor first according to the diagonal principle, and then pre-tighten the fixing bolts connecting the motor bracket to the rear drive axle assembly; S5. Tighten the motor bracket: Tighten the fixing bolts to the specified torque in the pre-tightening sequence.

2. A motor assembly method for controlling NVH of a rear drive axle according to claim 1, characterized in that: In step S2, the pre-tightening torque of the fixing bolt is performed at 30% of the specified torque.

3. The motor assembly method for controlling NVH of a rear drive axle according to claim 1, characterized in that: The pre-tightening sequence in step S2 is: first from top to bottom, then from left to right or from right to left, and finally pre-tightening diagonally downward.

4. A motor assembly method for controlling NVH of a rear drive axle according to claim 3, characterized in that: There are eight fixing bolts between the drive motor and the rear axle main reducer, six of which are located on the front of the rear axle main reducer, and the six fixing bolts are A, B, C, D, E, and F respectively; the other two fixing bolts are located on the back of the rear axle main reducer, and the two fixing bolts are G and H respectively.

5. The motor assembly method for controlling NVH of a rear drive axle according to claim 3, characterized in that: When the drive motor is located on the horizontal side of the front of the rear drive axle assembly, pre-tighten the fixing bolts in the order of B, F, D, G, C, H, A, and E.

6. The motor assembly method for controlling NVH of a rear drive axle according to claim 3, characterized in that: The drive motor is located above the rear drive axle assembly and the fixing bolts are pre-tightened in the order of D, G, B, F, C, H, E, and A.

7. The motor assembly method for controlling NVH of a rear drive axle according to claim 1, characterized in that: In step S4, the pre-tightening torque of the fixing bolt is performed at 30% of the prescribed torque.

8. The motor assembly method for controlling NVH of a rear drive axle according to claim 1, characterized in that: There are six fixing bolts between the drive motor and the tightening motor bracket, and the six fixing bolts are O, P, Q, R, S, and T.

9. The motor assembly method for controlling NVH of a rear drive axle according to claim 8, characterized in that: The pre-tightening sequence of fixing bolts O, P, Q, R, S, T is O, S, P, T, Q, N.

10. The motor assembly method for controlling NVH of a rear drive axle according to claim 1, characterized in that: The fixing tool is used to support the rear drive axle assembly.

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