Mute clearance compensation structure for tail end of worm of electric power steering system

Abstract

The utility model discloses an electric power steering system worm tail end mute clearance compensation structure which comprises a shell, a worm installation cavity and a worm wheel installation cavity are arranged in the shell, a worm is installed in the worm installation cavity, a worm wheel is installed in the worm wheel installation cavity, the worm is meshed with the worm wheel, and the worm wheel is meshed with the worm wheel. A motor assembly is mounted at one axial end of the worm, the end of a motor rotor of the motor assembly is in transmission connection with the worm through a coupler, an elastic ejector block is axially mounted between the worm and the motor rotor, and the motor rotor and the elastic ejector block are axially compressed to be stressed through axial compression between the motor rotor and the elastic ejector block. The elastic ejector block is compressed to generate pretightening force in the axial direction of the worm, so that the worm gear is in close fit with the worm, and meanwhile axial movement caused by abrasion of a bearing on the worm after long-time use is restrained.

Description

Technical Field

[0001] The utility model relates to the technical field of automobile electric power steering systems, in particular to a silent clearance compensation structure at the tail end of a worm of an electric power steering system. Background Art

[0002] Electric power steering (EPS) is a power steering system that relies on an electric motor to provide auxiliary torque. It is mainly composed of gear racks, sensors (torque and angle sensors), power motors, worm gear reduction mechanisms, controllers, etc. Because it uses green energy, provides variable steering assistance, and can improve handling stability, it has been widely used in today's automotive industry. The worm gear reduction mechanism is the most commonly used torque transmission mechanism in the steering system. It can amplify the output torque of the power motor and provide a suitable speed. However, in the long-term use process, the NVH problem caused by the axial clearance caused by the wear between the worm gears is common.

[0003] The current technical solution generally adopts a pre-tightening mechanism that adds a compression spring and a metal top block to the tail of the big end of the worm. The motor rotor presses against the metal top block to compress the spring to provide pre-tightening force to reduce the axial meshing clearance between the worm gear and suppress the axial movement of the big end bearing to optimize the noise. However, after the steering gear is used for a long time, this solution will increase the risk of noise generation under extreme working conditions such as bumpy roads and rapid reversing due to the risk of the metal top block rebounding and hitting the motor rotor, and the non-axial deformation of the compression spring hitting the inner wall of the worm, which will also affect the driver's driving experience. Utility Model Content

[0004] The utility model provides a silent clearance compensation structure at the tail end of a worm of an electric power steering system, which can effectively avoid the risk of noise caused by impacting the motor rotor and the inner wall of the worm, thereby greatly reducing the risk of NVH.

[0005] To achieve the above-mentioned purpose, the utility model provides the following technical solutions: a silent clearance compensation structure for the tail end of a worm of an electric power steering system, comprising a shell, a worm mounting cavity and a worm wheel mounting cavity being arranged inside the shell, a worm being mounted in the worm mounting cavity, a worm wheel being mounted in the worm wheel mounting cavity, the worm being meshed with the worm wheel, a motor assembly being mounted at one axial end of the worm, the end of the motor rotor of the motor assembly being connected to the worm transmission through a coupling, an elastic top block being axially mounted between the worm and the motor rotor, the elastic top block being compressed by the axial compression force between the motor rotor and the elastic top block to generate a preload force along the axial direction of the worm, so that the worm wheel and the worm are closely matched, and at the same time, the axial movement caused by the wear of the bearing on the worm after long-term use is suppressed.

[0006] Preferably, an inner concave connection cavity is provided at the end of the worm, and the elastic top block is embedded and positioned in the inner concave connection cavity. The inner concave connection cavity can limit the position of the elastic top block, enabling the elastic top block to be fully stressed.

[0007] Preferably, the coupling is a rubber coupling, and an insertion portion is provided at one axial end thereof. The insertion portion is embedded into the inner concave connection cavity. The rubber coupling is convenient to install and realizes axial connection by using elasticity and friction. Inserting the insertion portion into the inner concave connection cavity can achieve a firm axial transmission connection.

[0008] Preferably, the elastic top block includes a guiding portion and a plugging portion. The diameter of the guiding portion is the same as the inner cavity diameter of the inner concave connection cavity and abuts against the bottom of the inner concave connection cavity. The plugging portion is inserted into the insertion portion of the coupling and abuts against the motor rotor. When the guiding portion is compressed, it will radially extend, and the pre-tightening force is relatively large. The plugging portion can be limited by the insertion portion, ensuring that the elastic top block can be axially stressed.

[0009] Preferably, the outer side of one end of the worm close to the coupling is connected to the housing through a bearing. The axial side of the bearing facing the coupling abuts against the outer side of the worm axially. A limit snap ring connected to the housing is further provided on the axial side of the bearing facing the coupling. The bearing is firmly installed, which can further reduce axial play.

[0010] Compared with the prior art, the beneficial effects of the present utility model are:

[0011] It is to compensate for the axial meshing clearance between the worm and the worm wheel and the axial clearance of the bearing through the compression pre-tightening force of the elastic top block. At the same time, when the rubber top block rebounds, the damping property of the rubber is used to avoid impacting the motor rotor, the inner wall of the worm, and suppressing the risk of abnormal noise caused by axial play of the bearing. By providing the corresponding axial compensation force through the compression pre-tightening force of the elastic top block, the risk of collision noise between the inner wall of the worm and the compression spring, and between the motor rotor and the metal top block can be avoided; in terms of structure, the part designs of the metal top block and the compression spring can be omitted, and at the same time, the processing cycle of the inner cavity of the worm can be reduced, and the rubber top block has a relatively simple process forming and low cost. The production cycle is reduced during the assembly of the assembly, which can achieve a good effect of cost reduction and efficiency increase. Description of the Drawings

[0012] Figure 1 is the main view sectional structure diagram of the present utility model;

[0013] Figure 2 is Figure 1 the partial enlarged structure diagram of

[0014] Reference Signs:

[0015] 1. Worm, 11. Concave connecting cavity, 12. Coupling, 13. Insertion part, 2. Worm mounting cavity, 3. Housing, 4. Worm gear mounting cavity, 5. Worm gear, 6. Motor assembly, 7. Elastic top block, 71. Guide part, 72. Connecting part, 8. Bearing, 9. Limiting spring, 10. Motor rotor. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0017] like Figure 1-2 As shown, the utility model is to effectively avoid the risk of noise caused by impacting the motor rotor and the inner wall of the worm, thereby greatly reducing the risk of NVH. Provide the following technical solutions: A silent clearance compensation structure of the tail end of the worm of an electric power steering system, comprising a housing 3, a worm mounting cavity 2 and a worm wheel mounting cavity 4 are arranged inside the housing 3, a worm 1 is installed in the worm mounting cavity 2, a worm wheel 5 is installed inside the worm wheel mounting cavity 4, the worm 1 is meshed with the worm wheel 5, a motor assembly 6 is installed at one axial end of the worm 1, the end of the motor rotor 10 of the motor assembly 6 is connected to the worm 1 through a coupling 12, and an elastic top block 7 is axially installed between the worm 1 and the motor rotor 10, and the elastic top block 7 is compressed by the axial compression force between the motor rotor 10 and the elastic top block 7 to generate a preload along the axial direction of the worm 1, so that the worm wheel 5 and the worm 1 are closely matched, and at the same time, the axial movement caused by the wear of the bearing on the worm 1 after long-term use is suppressed.

[0018] Specifically, the motor assembly 6 and the housing 3 are threadedly connected, and the motor rotor 10 may include a rotor winding, a rotor core and a main shaft. A coupling 12 is installed at one end of the main shaft, which is connected to the worm 1 through the coupling. The position of the coupling 12 and the worm 1 can be axially adjusted so that the elastic top block 7 always applies an axial preload force to the main shaft and the worm 1. A limit block can also be sleeved on the main shaft, and the coupling 12 is against the limit block to limit the coupling 12.

[0019] In this embodiment, if Figure 2 As shown, a concave connecting cavity 11 is provided at the end of the worm 1, and the elastic top block 7 is embedded and positioned in the concave connecting cavity 11. The concave connecting cavity 11 can limit the position of the elastic top block 7 so that the elastic top block 7 can be fully stressed.

[0020] In this embodiment, if Figure 2As shown, the coupling 12 is a rubber coupling. An insertion part 13 is provided at one axial end of the rubber coupling. The insertion part 13 is embedded into the concave connection cavity 11. The rubber coupling is convenient to install, and realizes axial connection by using elasticity and friction. Inserting the insertion part 13 into the concave connection cavity 11 can achieve a firm axial transmission connection.

[0021] Among them, the elastic top block 7 includes a guiding part 71 and a plugging part 72. The diameter of the guiding part 71 is the same as the inner cavity diameter of the concave connection cavity 11 and abuts against the bottom of the concave connection cavity 11. The plugging part 72 is inserted into the insertion part 13 of the coupling 12 and abuts against the motor rotor 10. When the guiding part 71 is compressed, it will extend radially, and the pre-tightening force is relatively large. The plugging part 72 can be limited by the insertion part 13, ensuring that the elastic top block 7 can be axially stressed.

[0022] In order to reduce the axial runout of the worm 1, one end of the worm 1 close to the coupling 12 is connected to the housing 3 through a bearing 8 on the outside. The axial side of the bearing 8 facing the coupling 12 abuts against the outside of the worm 1 axially. A limit snap ring 9 connected to the housing 3 is further provided on the axial side of the bearing 8 facing the coupling 12. The bearing 8 is firmly installed, which can further reduce axial play.

[0023] In the case of initial assembly, the worm wheel 5 and the worm 1 have not been worn, the bearing 8 and the snap ring 9 have not been deformed, and the elastic top block 7 is in a compressed pre-tightened state; after long-term use, the worm wheel 5 and the worm 1 are worn, and after the bearing 8 and the snap ring 9 are worn and deformed, a gap is generated between the worm 1 and the worm wheel 5. Due to compression, the elastic top block 7 provides a certain axial force to the worm 1, so as to ensure that the tooth surfaces of the worm 1 and the worm wheel 5 always remain in contact, and at the same time suppress axial play when the bearing is stressed, thereby optimizing the noise.

[0024] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relative position relationship and movement conditions between components in a certain specific posture (as shown in the drawings). If this specific posture changes, the directional indication will also change accordingly.

[0025] In addition, in the present invention, descriptions such as "first" and "second" are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0026] In the present utility model, unless otherwise clearly stipulated and defined, terms such as "connection" and "fixation" shall be understood in a broad sense. For example, "fixation" may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements or the interaction relationship between two elements, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0027] In addition, the technical solutions between various embodiments of the present utility model can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present utility model.

Claims

1. A silent clearance compensation structure for the tail end of a worm gear of an electric power steering system, comprising: A housing (3), wherein a worm mounting cavity (2) and a worm wheel mounting cavity (4) are arranged inside the housing (3), a worm (1) is mounted inside the worm mounting cavity (2), a worm wheel (5) is mounted inside the worm wheel mounting cavity (4), and the worm (1) and the worm wheel (5) are meshed, characterized in that: A motor assembly (6) is installed at one axial end of the worm (1); an end of a motor rotor (10) of the motor assembly (6) is drivingly connected to the worm (1) via a coupling (12); and an elastic top block (7) is also axially installed between the worm (1) and the motor rotor (10).

2. The silent clearance compensation structure at the worm end of the electric power steering system according to claim 1, characterized in that: The end of the worm (1) is provided with a concave connecting cavity (11), and the elastic top block (7) is embedded and positioned in the concave connecting cavity (11).

3. The silent clearance compensation structure at the worm end of the electric power steering system according to claim 2, characterized in that: The coupling (12) is a rubber coupling, and an insertion portion (13) is provided at one axial end thereof. The insertion portion (13) is embedded in the concave connecting cavity (11).

4. The silent clearance compensation structure at the worm end of the electric power steering system according to claim 3, wherein: The elastic top block (7) comprises a guide portion (71) and an insert portion (72); the diameter of the guide portion (71) is the same as the inner diameter of the inner concave connecting cavity (11) and abuts against the bottom of the inner concave connecting cavity (11); the insert portion (72) is inserted into the insertion portion (13) of the coupling (12) and abuts against the motor rotor (10).

5. The silent clearance compensation structure at the worm end of the electric power steering system according to claim 1, characterized in that: The outer side of one end of the worm (1) close to the coupling (12) is connected to the housing (3) via a bearing (8); the side of the bearing (8) axially facing the coupling (12) is axially in contact with the outer side of the worm (1); and the side of the bearing (8) axially facing the coupling (12) is also provided with a limit spring (9) connected to the housing (3).

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