Electric power steering worm assembly semi-finished product

Abstract

This utility model discloses a semi-finished worm gear assembly for an electric power steering system, comprising a gear shaft and a worm gear blank. The gear shaft is mounted on the worm gear blank, which includes a worm gear core and a worm gear ring disposed on the worm gear core. A mating hole for inserting the gear shaft is provided at the center of the worm gear core, and the worm gear ring surrounds the outer ring of the worm gear core. This semi-finished worm gear assembly for an electric power steering system, in which the gear shaft and worm gear blank are assembled into an integrated structure, allows for integrated processing, facilitating subsequent processing to form the final worm gear assembly. It solves problems such as poor tooth profile accuracy and deformation caused by assembly in worm gears, thus improving product quality.

Description

Technical Field

[0001] This utility model belongs to the technical field of vehicle steering systems. Specifically, this utility model relates to a semi-finished worm gear assembly for an electric power steering system. Background Technology

[0002] Currently, most automotive electric power steering systems use worm gear transmission to transmit motor torque to the worm. The torque is amplified and transmitted to the worm gear through worm gear meshing. The torque is then transmitted to the gear shaft through the worm gear assembly structure. The gear shaft drives the rack to generate thrust, which is then applied to the steering knuckle arm through the steering tie rod to achieve steering of the tires.

[0003] As a key component for torque transmission, the accuracy of the worm gear tooth profile and the positional relationship between the worm gear tooth profile and the gear shaft tooth profile directly affect the meshing accuracy of the worm gear and worm, as well as the meshing accuracy of the gear and rack.

[0004] Existing worm gear assemblies are generally formed by pressing a pre-machined worm gear with a gear shaft. Worm gear assemblies obtained in this way suffer from radial runout and deformation of the worm gear teeth due to the pressing force during assembly. This reduces the meshing accuracy of the worm gear and worm, resulting in problems such as large torque fluctuations in the steering gear assembly, uneven feel, and vibration and noise.

[0005] Chinese Patent Application No. 202421920415.6 discloses a steering gear, an electric steering system, and a vehicle. The steering gear in this application includes a transmission assembly and a backlash compensation assembly. The transmission assembly includes a worm gear and a worm, which are coupled in a transmission relationship. The backlash compensation assembly includes a guide member, an eccentric member, and an elastic member. The eccentric member is connected to both the worm and the elastic member, and provides driving force under the influence of the elastic member. The guide member is connected to the eccentric member and sleeved on the worm, guiding the direction of the driving force to move the worm in a first direction, which is the direction closer to the worm gear. The technical solution disclosed in this patent document also fails to solve the aforementioned technical problems.

[0006] A semi-finished worm gear assembly for an electric power steering system is provided, particularly regarding how to conveniently process the worm gear assembly. Utility Model Content

[0007] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention provides a semi-finished worm gear assembly for an electric power steering system, the purpose of which is to facilitate the processing of the worm gear assembly.

[0008] To achieve the above objectives, the technical solution adopted by this utility model is as follows: a semi-finished worm gear assembly for an electric power steering system, comprising a gear shaft and a worm gear blank, wherein the gear shaft is mounted on the worm gear blank, and the worm gear blank comprises a worm gear core and a worm gear ring disposed on the worm gear core, wherein a mating hole for inserting the gear shaft is provided at the center of the worm gear core, and the worm gear ring surrounds the outer ring portion of the worm gear core.

[0009] The worm gear ring is injection molded onto the worm gear core.

[0010] The worm gear core also includes an inner ring portion, which is coaxial with the outer ring portion. The inner ring portion and the outer ring portion are fixedly connected by a connecting portion, and the mating hole is located at the center of the inner ring portion.

[0011] The thickness of the connecting portion is less than the thickness of the inner ring portion and the outer ring portion.

[0012] The worm gear blank and the gear shaft are interference fit.

[0013] The gear shaft includes a mounting portion and a toothed portion arranged sequentially along the axial direction. The toothed portion is provided with teeth for meshing with the rack of the electric power steering system. The mounting portion is inserted into the mating hole and is provided with a central hole. The opening of the central hole is provided with an inner chamfer.

[0014] This utility model discloses a semi-finished worm gear assembly for an electric power steering system. The gear shaft and worm gear blank are assembled into an integrated structure, which can achieve integrated processing and facilitate subsequent processing to form the final worm gear assembly. This solves the problems of poor tooth profile accuracy and deformation caused by assembly of worm gears, and improves product quality. Attached Figure Description

[0015] This manual includes the following figures, which illustrate the following:

[0016] Figure 1 This is a disassembly diagram of a semi-finished worm gear assembly for an electric power steering system according to this utility model.

[0017] Figure 2 This is the front view of the gear shaft;

[0018] Figure 3 This is a sectional view of the worm gear blank;

[0019] Figure 4 This is a schematic diagram of the worm gear assembly mechanism connection;

[0020] The markings in the figure are as follows: 1. Gear shaft; 101. Inner chamfer; 102. Mounting part; 103. Tooth profile; 104. Center hole; 2. Worm gear blank; 201. Worm gear ring; 202. Connecting part; 203. Mating hole; 204. Inner ring part; 205. Outer ring part; 3. Worm gear; 301. Worm gear tooth profile. Detailed Implementation

[0021] The specific embodiments of this utility model will be further described in detail below with reference to the accompanying drawings, in order to help those skilled in the art to have a more complete, accurate and in-depth understanding of the concept and technical solution of this utility model, and to facilitate its implementation.

[0022] like Figures 1 to 3 As shown, this utility model provides a semi-finished worm gear assembly for an electric power steering system, including a gear shaft 1 and a worm gear blank 2. The gear shaft 1 is mounted on the worm gear blank 2, and the worm gear blank 2 and the gear shaft 1 are interference-fitted. The worm gear blank 2 includes a worm gear core and a worm gear ring 201 disposed on the worm gear core. A mating hole 203 for inserting the gear shaft 1 is provided at the center of the worm gear core, and the worm gear ring 201 surrounds the outer ring portion 205 of the worm gear core.

[0023] Specifically, such as Figures 1 to 3 As shown, the worm gear ring 201 has a circular ring structure and is injection molded onto the worm gear core. The worm gear ring 201 is coaxial with the worm gear core. The worm gear core also includes an inner ring portion 204, which is coaxially arranged with an outer ring portion 205. Both the inner ring portion 204 and the outer ring portion 205 have circular ring structures. The diameter of the outer ring portion 205 is larger than the diameter of the inner ring portion 204. The inner ring portion 204 and the outer ring portion 205 are fixedly connected by a connecting portion 202. A mating hole 203 is provided at the center of the inner ring portion 204. The thickness of the connecting portion 202 is less than the thickness of the inner ring portion 204 and the outer ring portion 205.

[0024] like Figures 1 to 3 As shown, the gear shaft 1 includes a mounting portion 102 and a toothed portion arranged sequentially and fixedly connected along the axial direction. The toothed portion has toothed profiles 103 for meshing with the rack of the electric power steering system. The mounting portion 102 is inserted into a mating hole 203 and has a center hole 104. An inner chamfer 101 is provided at the opening of the center hole 104. The mounting portion 102 on the gear shaft 1 is pressed into the mating hole 203 on the worm gear blank 2 and has an interference fit with the worm gear blank 2. One end of the toothed portion is fixedly connected to the mounting portion 102, and the other end of the mounting portion 102 has a center hole 104. The axis of the center hole 104 is colinear with the axis of the gear shaft 1. The center hole 104 and the inner chamfer 101 serve as positioning references when machining the worm gear blank 2. By machining away the excess material from the outer circle and end face of the worm gear blank 2, the worm gear toothed profile 301 is obtained, forming the final worm gear 3, thus realizing the machining of the worm gear assembly.

[0025] like Figures 1 to 3As shown, the center hole 104 at the first end of the gear shaft 1 and the inner chamfer 101 at the second end are coaxially arranged. The tooth profile 103 of the gear shaft 1 and the mounting part 102 are machined with the center hole 104 at the first end and the inner chamfer 101 at the second end of the gear shaft 11 as positioning references. Therefore, the center hole 104 and the inner chamfer 101 also serve as positioning references when machining the mounting part 102 and the tooth profile 103 of the gear shaft 1.

[0026] The worm gear tooth profile 301 is obtained by machining the outer circle and end face of the worm gear blank 2 with the center hole 104 at the first end of the gear shaft 1 and the inner chamfer 101 at the second end as positioning references. The accuracy and positional accuracy of the worm gear tooth profile 301 and the tooth profile 103 of the gear shaft 1 are ensured by sharing the machining references.

[0027] like Figure 4 As shown, gear shaft 1 meshes with the rack of the electric power steering system, and worm wheel 3 meshes with the worm assembly of the electric power steering system. When the electric power steering system is working, it transmits the controllable motor torque to the worm assembly. The worm assembly transmits the torque to the worm wheel 3 and amplifies the torque through the meshing of the worm teeth and the worm wheel teeth 301. The worm wheel 3 transmits the torque to the gear shaft 1 through the interference fit 202 with the gear shaft 1. The gear shaft 1 transmits the torque to the rack through the meshing of the teeth 103 and the rack teeth, converting the torque into rack thrust to achieve power steering.

[0028] The above-described semi-finished worm gear assembly for electric power steering has the following advantages:

[0029] Assembling the gear shaft 1 and the worm gear blank 2 into a single unit allows for integrated machining, facilitating subsequent processing to form the final worm gear assembly. This eliminates the need for press-fitting the worm gear to the gear shaft 1, and also removes the requirement for quality control of the press-fitting force. This solves problems such as poor tooth profile accuracy and deformation caused by assembly issues in the worm gear, thus improving product quality. The part has a simple and reliable structure, and is easy to machine.

[0030] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention; or the direct application of the inventive concept and technical solution to other situations without modification, are all within the protection scope of the present invention.

Claims

1. A semi-finished worm gear assembly for an electric power steering system, comprising a gear shaft and a worm gear blank, wherein the gear shaft is mounted on the worm gear blank, characterized in that, The worm gear blank includes a worm gear core and a worm gear ring disposed on the worm gear core. A mating hole for inserting the gear shaft is provided at the center of the worm gear core, and the worm gear ring covers the outer ring of the worm gear core.

2. The semi-finished worm gear assembly for electric power steering according to claim 1, characterized in that, The worm gear ring is injection molded onto the worm gear core.

3. The semi-finished worm gear assembly for electric power steering according to claim 1, characterized in that, The worm gear core also includes an inner ring portion, which is coaxial with the outer ring portion. The inner ring portion and the outer ring portion are fixedly connected by a connecting portion, and the mating hole is located at the center of the inner ring portion.

4. The semi-finished worm gear assembly for an electric power steering system according to claim 3, characterized in that, The thickness of the connecting portion is less than the thickness of the inner ring portion and the outer ring portion.

5. The semi-finished worm gear assembly for an electric power steering system according to any one of claims 1 to 4, characterized in that, The worm gear blank and the gear shaft are interference fit.

6. The semi-finished worm gear assembly for an electric power steering system according to any one of claims 1 to 4, characterized in that, The gear shaft includes a mounting portion and a toothed portion arranged sequentially along the axial direction. The toothed portion is provided with teeth for meshing with the rack of the electric power steering system. The mounting portion is inserted into the mating hole and is provided with a mounting hole. The opening of the mounting hole is provided with an inner chamfer.

Images