An eps worm and wheel gap compensation mechanism for improving NVH performance

Abstract

This utility model relates to the technical field of automotive electric power steering systems, and discloses an EPS worm gear backlash compensation mechanism to improve NVH performance. It includes a protective housing, within which a floating support and a first bearing are installed. The floating support includes a support frame and a second bearing. The support frame of the floating support is fixedly installed on the inner wall of the housing. The inner rings of the second and first bearings of the floating support are jointly and fixedly connected to the worm gear body. This utility model ensures smooth axial movement through a pushrod side exhaust groove design, and simultaneously employs HNBR and POM buffer pads for dual vibration absorption and limiting, effectively preventing the worm gear body from deviating from the theoretical meshing state under power-assisted conditions. Furthermore, buffer protective pads are configured on both sides of the first bearing. Combined with the interference fit of the coupling and the minimal axial backlash design, this not only prevents abnormal noise caused by sudden changes in force on the worm gear body due to steel ball impact, but also absorbs micro-axial movement through the buffer pads, significantly improving NVH performance.

Description

Technical Field

[0001] This utility model relates to the technical field of automotive electric power steering systems, specifically to an EPS worm gear backlash compensation mechanism for improving NVH performance. Background Technology

[0002] EPS (Electric Power Steering) is a new type of power steering system that provides dynamic assistance strategies under different road conditions through the ECU control unit, improving self-centering and road feel. It is widely used in pure electric vehicles, SUVs, pickup trucks, and off-road vehicles. As vehicle size and weight increase, the requirements for the durability and comfort of EPS become higher. The core mechanism of EPS is a worm gear reducer, which reduces and increases the torque of the motor, then converts it into axial force through a rack and pinion mechanism to achieve steering assistance. However, the worm gear is made of nylon to reduce NVH (Noise, Vibration, and Harshness), which has lower wear resistance than metal and is prone to wear after long-term use. Furthermore, nylon is sensitive to the environment; changes in temperature and humidity can cause fluctuations in the worm gear size, thus altering the worm gear meshing clearance. This clearance variation can cause problems such as EPS looseness, abnormal noise, and steering sticking, affecting driving smoothness. Therefore, to ensure the durability, reliability, and environmental adaptability of the worm gear reducer, a worm gear clearance adjustment mechanism needs to be added to the worm gear mechanism to compensate for changes in the worm gear clearance and ensure product reliability.

[0003] Existing clearance adjustment mechanisms rely on internal grease seals, which obstruct the movement of the push rod and prevent it from effectively adjusting the clearance. Furthermore, insufficient axial clearance between the push rod and the internal components after assembly can easily lead to impact noises. Excessive bearing clearance exacerbates these problems. While existing technologies use axial springs and buffer couplings for preload to suppress worm gear movement, excessive preload can accelerate motor and bearing damage, increase system friction, and the sudden change in preload during reversal, lacking side buffering, can still cause bearing impact noises. Therefore, those skilled in the art require a clearance compensation mechanism for EPS worm gears to improve NVH performance and address the problems mentioned in the background. Utility Model Content

[0004] The purpose of this invention is to provide an EPS worm gear backlash compensation mechanism that improves NVH performance and solves the problems mentioned in the background art.

[0005] This utility model provides the following technical solution: an EPS worm gear backlash compensation mechanism for improving NVH performance, comprising a protective housing, a floating support and a first bearing installed inside the housing, the floating support including a support frame and a second bearing, the support frame of the floating support being fixedly installed on the inner wall of the housing, the inner ring of the second bearing and the inner ring of the first bearing of the floating support being fixedly connected to a worm body, a worm wheel body being rotatably connected to one side of the inner wall of the housing, the worm body and the worm wheel body meshing with each other, a backlash compensation component for pushing the worm body closer to the worm wheel body being installed inside the housing, and a protective component for protecting the first bearing being provided on the outer wall of the worm body.

[0006] As a preferred embodiment of the above technical solution, the gap compensation component includes a fixed cylinder, which is fixedly connected to one side of the inner wall of the housing. A push rod is slidably connected to the inner wall of the housing. One end of the push rod is disposed on the outer ring of the floating support. A placement groove is provided on the side of the push rod away from the floating support. A spring is fixedly connected to the end of the placement groove near the floating support. An exhaust groove is provided on the side wall of the push rod.

[0007] As a preferred embodiment of the above technical solution, an HNBR buffer pad is fixedly connected to the inner wall of the fixed cylinder on the side away from the floating support. The HNBR buffer pad is arranged in a ring shape, and a POM buffer pad is sleeved inside the HNBR buffer pad. The end of the spring near the HNBR buffer pad is located on the side wall of the POM buffer pad.

[0008] As a preferred embodiment of the above technical solution, the protective component includes a buffer protective pad and an O-ring. Two buffer protective pads are provided, and the two buffer protective pads are respectively sleeved on the outside of the worm body on the side away from the floating support. The two buffer protective pads are symmetrically arranged on both sides of the first bearing. The O-ring is disposed on the inner wall of the inner ring of the first bearing and is sleeved on the outside of the worm body. A coupling is fixedly installed at the end of the worm body away from the floating support.

[0009] As a preferred embodiment of the above technical solution, the inner wall of the fixed cylinder is coated with grease, and the grease is disposed between the fixed cylinder and the top rod.

[0010] As a preferred embodiment of the above technical solution, the first bearing is a 4P bearing, and the shaft diameter at the mating point between the worm gear body and the inner ring of the first bearing adopts an arc surface fit.

[0011] Compared with the prior art, the beneficial effects of this utility model are:

[0012] 1. By milling vent grooves on the side of the push rod, an venting channel is provided for the axial movement of the push rod in the fixed cylinder, avoiding the risk of obstructed axial movement of the push rod in the fixed cylinder. At the same time, HNBR buffer pads and POM buffer pads are added at the contact points between the push rod and the inner wall of the fixed cylinder for buffering and vibration absorption. When the push rod is subjected to the axial force of the second bearing of the floating support, the push rod moves axially towards the bottom end face of the inner wall of the fixed cylinder. The push rod first contacts the POM buffer pad, and the POM buffer pad then compresses the HNBR buffer pad to buffer and absorb vibration. After compression, the POM buffer pad contacts the bottom of the inner wall of the fixed cylinder, which plays a limiting role and prevents the worm gear body from moving too far away from the theoretical meshing state in the assisted state.

[0013] 2. Buffer protective pads are used on both sides of the first bearing. The first bearing is axially press-fitted with the worm gear body through an interference fit of the coupling. The rapid switching of the coupling's assist direction causes the axial force direction of the worm gear body to change rapidly. Since the axial clearance of the first bearing is extremely small, the risk of abnormal noise from the impact between the inner and outer rings of the first bearing and the steel balls is avoided. At the same time, buffer protective pads are evenly distributed on both sides of the first bearing. When the worm gear body moves slightly under axial force, the buffer protective pads play a role in buffering and absorbing vibration, further eliminating the risk of abnormal noise from the impact between the inner and outer rings of the first bearing and the steel balls. Attached Figure Description

[0014] Figure 1 A schematic diagram of the main structure of an EPS worm gear backlash compensation mechanism for improving NVH performance;

[0015] Figure 2 A schematic diagram of the worm and worm wheel structure of an EPS worm gear backlash compensation mechanism to improve NVH performance;

[0016] Figure 3 A structurally exploded view of the backlash compensation component of an EPS worm gear backlash compensation mechanism for improving NVH performance;

[0017] Figure 4 A cross-sectional view of the clearance compensation component structure of an EPS worm gear clearance compensation mechanism for improving NVH performance;

[0018] Figure 5 This is an exploded view of the protective component structure of an EPS worm gear backlash compensation mechanism for improving NVH performance.

[0019] Legend:

[0020] 1. Housing; 2. Floating support; 3. First bearing; 4. Worm gear body; 5. Worm wheel body; 6. Clearance compensation assembly; 601. Fixed cylinder; 602. Push rod; 603. Placement groove; 604. Spring; 605. Exhaust groove; 606. HNBR buffer pad; 607. POM buffer pad; 7. Protective assembly; 701. Buffer protective pad; 702. O-ring; 703. Coupling. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention.

[0022] Please see Figures 1-5 As shown, this utility model provides a technical solution: an EPS worm gear backlash compensation mechanism for improving NVH performance, including a protective housing 1, a floating support 2 and a first bearing 3 installed inside the housing 1, the floating support 2 including a support frame and a second bearing, the support frame of the floating support 2 being fixedly installed on the inner wall of the housing 1, the inner ring of the second bearing of the floating support 2 and the inner ring of the first bearing 3 being fixedly connected to a worm body 4, a worm gear body 5 being rotatably connected to one side of the inner wall of the housing 1, the worm body 4 and the worm gear body 5 meshing with each other, a backlash compensation component 6 for pushing the worm body 4 toward the worm gear body 5 being installed inside the housing 1, and a protective component 7 for protecting the first bearing 3 being provided on the outer wall of the worm body 4.

[0023] As one implementation method in this embodiment, please refer to Figures 1-4 As shown, the gap compensation component 6 includes a fixed cylinder 601, which is fixedly connected to one side of the inner wall of the housing 1. A push rod 602 is slidably connected to the inner wall of the housing 1. One end of the push rod 602 is disposed on the outer ring of the floating support 2. A placement groove 603 is provided on the side of the push rod 602 away from the floating support 2. A spring 604 is fixedly connected to the end of the placement groove 603 near the floating support 2. An exhaust groove 605 is provided on the side wall of the push rod 602.

[0024] An HNBR buffer pad 606 is fixedly connected to the inner wall of the fixed cylinder 601 on the side away from the floating support 2. The HNBR buffer pad 606 is arranged in a ring shape. A POM buffer pad 607 is sleeved inside the HNBR buffer pad 606. The end of the spring 604 near the HNBR buffer pad 606 is set on the side wall of the POM buffer pad 607.

[0025] Furthermore, the spring 604 drives the push rod 602 to slide within the fixed cylinder 601, causing the push rod 602 to push the second bearing on the floating support 2 to slide axially on the support frame. This pushes one end of the worm body 4 closer to the worm wheel body 5, compensating for the change in clearance between the worm wheel body 5 and the worm body 4, ensuring reliable meshing. Since the push rod 602 has a milled exhaust groove 605 on its side, it serves as an exhaust channel for the axial movement of the push rod 602 within the fixed cylinder 601, avoiding the risk of obstructed axial movement of the push rod 602 within the fixed cylinder 601. Simultaneously, the push rod 602 and the fixed cylinder 601... HNBR buffer pad 606 and POM buffer pad 607 are added to the contact area of ​​the inner wall to buffer and absorb vibration. When the push rod 602 is subjected to the axial force of the second bearing of the floating support 2, the push rod 602 moves axially towards the bottom end face of the inner wall of the fixed cylinder 601. The push rod 602 first contacts the POM buffer pad 607, and the POM buffer pad 607 then compresses the HNBR buffer pad 606 to buffer and absorb vibration. After compression, the POM buffer pad 607 contacts the bottom of the inner wall of the fixed cylinder 601, which plays a limiting role and prevents the worm gear body 4 from moving too far away from the theoretical meshing state in the assisted state.

[0026] The floating support 2 is an existing technology, a support structure that can freely expand and contract with thermal expansion and contraction or load changes. It avoids stress concentration or deformation damage by reducing fixed constraints. It consists of a sliding bearing and an elastic element. While ensuring the reliability of the support, it retains the axial displacement freedom of the sliding bearing. It will not be described in detail here.

[0027] As one implementation method in this embodiment, please refer to Figure 1 and Figure 5 As shown, the protective component 7 includes a buffer protective pad 701 and an O-ring 702. There are two buffer protective pads 701, which are respectively sleeved on the outside of the worm body 4 on the side away from the floating support 2. The two buffer protective pads 701 are symmetrically arranged on both sides of the first bearing 3. The O-ring 702 is disposed on the inner wall of the inner ring of the first bearing 3 and is sleeved on the outside of the worm body 4. A coupling 703 is fixedly installed at the end of the worm body 4 away from the floating support 2.

[0028] Furthermore, buffer protective pads 701 are used on both sides of the first bearing 3. They are axially press-fitted with the worm body 4 through a coupling 703 with an interference fit. The coupling 703 facilitates rapid switching of the direction of force, which causes the axial force direction of the worm body 4 to change rapidly. Since the axial clearance of the first bearing 3 is extremely small, the risk of abnormal noise from the impact between the inner and outer rings of the first bearing 3 and the steel balls is avoided. At the same time, the buffer protective pads 701 are evenly distributed on both sides of the first bearing 3. When the worm body 4 moves slightly under axial force, the buffer protective pads 701 play a role in buffering and absorbing vibration, further eliminating the risk of abnormal noise from the impact between the inner and outer rings of the first bearing 3 and the steel balls. In addition, the worm body 4 and the first bearing 3 are supported by an O-ring 702 with an interference fit in the middle, which plays a role in radial support of the worm body 4 and the first bearing 3, buffering and absorbing vibration, and avoiding abnormal noise from radial impact between the worm body 4 and the first bearing 3.

[0029] As one implementation method in this embodiment, please refer to Figure 4 As shown, the inner wall of the fixed cylinder 601 is coated with grease, and the grease is located between the fixed cylinder 601 and the top rod 602.

[0030] Furthermore, the grease can effectively reduce the frictional resistance between the fixed cylinder 601 and the push rod 602, reduce wear during movement, and ensure that the push rod 602 slides smoothly and steadily within the fixed cylinder 601.

[0031] As one implementation method in this embodiment, please refer to Figure 1 , Figure 2 and Figure 5 As shown, the first bearing 3 is a 4P bearing, and the shaft diameter at the mating point between the worm gear body 4 and the inner ring of the first bearing 3 adopts a circular arc surface fit.

[0032] Furthermore, the 4P bearing, with its high-rigidity double-row structure and bidirectional axial load capacity, can effectively cope with the complex composite loads in the transmission of the worm gear body 4. Its precision raceway design ensures high precision in the meshing of the worm gear body 4 and the worm wheel body 5, reducing vibration and noise during transmission. The preload adjustment function can eliminate axial clearance and improve the stability of system operation. The shaft diameter at the mating point between the worm gear body 4 and the inner ring of the first bearing 3 adopts an arc surface fit, allowing the worm gear body 4 to swing angularly within the inner ring of the first bearing 3. In conjunction with the clearance compensation component 6, it realizes the function of adjusting the clearance between the worm wheel body 5 and the worm gear body 4.

[0033] Working principle: Spring 604 drives push rod 602 to slide within fixed cylinder 601, causing push rod 602 to push the second bearing on floating support 2 to slide axially on the support frame. This pushes one end of worm body 4 closer to worm wheel body 5, compensating for the clearance changes between worm wheel body 5 and worm body 4, ensuring reliable meshing. Since vent groove 605 is milled on the side of push rod 602, it serves as a venting channel for axial movement of push rod 602 within fixed cylinder 601, preventing push rod 602 from being damaged within the fixed cylinder. To mitigate the risk of impaired axial movement in 601, HNBR buffer pads 606 and POM buffer pads 607 are added at the contact point between the push rod 602 and the inner wall of the fixed cylinder 601 for damping and vibration absorption. When the push rod 602 is subjected to axial force from the second bearing of the floating support 2, the push rod 602 moves axially towards the bottom end face of the inner wall of the fixed cylinder 601. The push rod 602 first contacts the POM buffer pad 607, which then compresses the HNBR buffer pad 606 to dampen and absorb vibration. After compression, the POM buffer pad 607 contacts the bottom of the inner wall of the fixed cylinder 601, which serves as a limit to prevent the worm gear body 4 from moving too far away from the theoretical meshing state in the assisted state. The first bearing 3 is protected by buffer pads 701 on both sides, which are axially press-fitted to the worm gear body 4 via a coupling 703 with an interference fit. The rapid switching of the assist direction by the coupling 703 causes a rapid change in the axial force direction of the worm gear body 4. Due to the extremely small axial clearance of the first bearing 3, the risk of abnormal noise from the impact between the inner and outer rings of the first bearing 3 and the steel balls is avoided. Simultaneously, the buffer pads 701 are evenly distributed on both sides of the first bearing 3. When the worm gear body 4 experiences slight axial movement, the buffer pads 701 act as a buffer and vibration absorber, further eliminating the risk of abnormal noise from the impact between the inner and outer rings of the first bearing 3 and the steel balls. Furthermore, the worm gear body 4 and the first bearing 3 are supported by an O-ring 702 with an interference fit in the middle, providing radial support for the worm gear body 4 and the first bearing 3, which also acts as a buffer and vibration absorber, preventing radial impact noise between the worm gear body 4 and the first bearing 3, thereby significantly improving NVH performance.

[0034] The above embodiments are only used to illustrate the technical solution of this utility model, and are not intended to limit it.

Claims

1. An EPS worm gear backlash compensation mechanism for improving NVH performance, comprising a housing (1) for protection, characterized in that: The housing (1) is equipped with a floating support (2) and a first bearing (3). The floating support (2) includes a support frame and a second bearing. The support frame of the floating support (2) is fixedly installed on the inner wall of the housing (1). The inner ring of the second bearing of the floating support (2) and the inner ring of the first bearing (3) are fixedly connected to the worm body (4). The worm wheel body (5) is rotatably connected to one side of the inner wall of the housing (1). The worm body (4) and the worm wheel body (5) mesh with each other. The housing (1) is equipped with a clearance compensation component (6) for pushing the worm body (4) closer to the worm wheel body (5). The outer wall of the worm body (4) is provided with a protective component (7) for protecting the first bearing (3).

2. The EPS worm gear backlash compensation mechanism for improving NVH performance according to claim 1, characterized in that: The gap compensation component (6) includes a fixed cylinder (601), which is fixedly connected to one side of the inner wall of the housing (1). A push rod (602) is slidably connected to the inner wall of the housing (1). One end of the push rod (602) is located on the outer ring of the floating support (2). A placement groove (603) is provided on the side of the push rod (602) away from the floating support (2). A spring (604) is fixedly connected to the end of the placement groove (603) near the floating support (2). An exhaust groove (605) is provided on the side wall of the push rod (602).

3. The EPS worm gear backlash compensation mechanism for improving NVH performance according to claim 2, characterized in that: An HNBR buffer pad (606) is fixedly connected to the inner wall of the fixed cylinder (601) away from the floating support (2). The HNBR buffer pad (606) is arranged in a ring shape. A POM buffer pad (607) is sleeved inside the HNBR buffer pad (606). The end of the spring (604) near the HNBR buffer pad (606) is set on the side wall of the POM buffer pad (607).

4. The EPS worm gear backlash compensation mechanism for improving NVH performance according to claim 1, characterized in that: The protective component (7) includes a buffer protective pad (701) and an O-ring (702). There are two buffer protective pads (701). The two buffer protective pads (701) are respectively sleeved on the outside of the worm body (4) away from the floating support (2). The two buffer protective pads (701) are symmetrically arranged on both sides of the first bearing (3). The O-ring (702) is set on the inner wall of the inner ring of the first bearing (3). The O-ring (702) is sleeved on the outside of the worm body (4). A coupling (703) is fixedly installed at the end of the worm body (4) away from the floating support (2).

5. The EPS worm gear backlash compensation mechanism for improving NVH performance according to claim 2, characterized in that: The inner wall of the fixed cylinder (601) is coated with grease, and the grease is disposed between the fixed cylinder (601) and the top rod (602).

6. The EPS worm gear backlash compensation mechanism for improving NVH performance according to claim 1, characterized in that: The first bearing (3) is a 4P bearing, and the shaft diameter of the worm body (4) and the inner ring of the first bearing (3) are fitted with a circular arc surface.

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