Automobile steering speed reducer and assembly process thereof

Abstract

The invention discloses an automobile steering speed reducer which comprises a speed reducer shell, a worm, a worm gear assembly and a bearing seat assembly, the bearing seat assembly is installed on the worm through a first bearing, the bearing seat assembly comprises a bearing seat body and an elastic element arranged on the bearing seat body, and the elastic element makes contact with the inner circle face of the speed reducer shell. A second bearing is arranged on the worm, a mounting hole for containing the worm and a bearing hole for containing the second bearing are formed in the speed reducer shell, and a certain vertical distance is formed between the axis of the mounting hole and the axis of the bearing hole. According to the automobile steering speed reducer, the elastic element is arranged on the bearing seat, meanwhile, the mounting hole is an eccentric hole, and the elastic element always generates force enabling the worm to be close to the worm gear, so that it is guaranteed that noise generated by a large meshing gap between the worm gear and the worm is avoided, and noise generated in the working process of the speed reducer is reduced; the operation experience of the driver is improved. The invention further discloses an assembling process of the automobile steering speed reducer.

Description

Technical Field

[0001] The invention belongs to the technical field of automobile electric power steering systems, and in particular, relates to an automobile steering reducer and an assembly process thereof. Background Art

[0002] The trend towards electrification of automobile steering is very obvious, and the installation rate of electric power steering systems is getting higher and higher; the electric power steering system includes a steering reducer, which increases the torque of the power motor to reduce the steering torque when the driver turns the steering wheel to make the vehicle turn.

[0003] The existing electric power steering system includes a reducer, and the reducer adopts a worm gear structure.

[0004] 1) The worm wheel is made of engineering plastic material, while the worm is made of steel material. First, the worm wheel material is affected by temperature and humidity changes, and its geometric dimensions will expand or shrink; secondly, the worm wheel and the worm will wear out after long-term meshing operation, and the size of the worm wheel will become smaller. In the above case, there will be a meshing gap between the worm wheel and the worm, and it will gradually increase. When the vehicle is steering, there will be obvious abnormal noise, which affects the driving comfort. In order to eliminate or improve the meshing gap of the worm wheel and the worm, a gap compensation mechanism is generally set on the reducer. The compensation mechanism of the prior art is basically composed of a slider spring seat, a compensation spring, a bearing, a push rod, etc., and the structure and assembly process are complex and costly. At the same time, when the driver performs a reversing operation at a speed of more than 200 degrees / second, this structure will produce an obvious "clacking" sound, and the driver's operating experience is poor. This is because: on the one hand, the permanent deformation of the compensation spring causes the stiffness to decay, and on the other hand, since the slider spring seat, the compensation spring and the housing in this mechanism are all in hard contact, the collision between metal parts cannot be avoided;

[0005] 2) The worm adopts the bearing support method at both ends, with a self-aligning ball bearing at the large end and a deep groove ball bearing at the small end, so as to realize the swing of the worm to complete the clearance compensation action. Therefore, the self-aligning ball bearing has a large clearance. At the same time, the shaft diameter of the small end of the worm and the inner ring of the deep groove ball bearing at the small end are also clearance-matched, which causes the two bearings to make a large noise during operation. Moreover, with long-term use, the noise of the reducer will become louder, and the driver's operating experience will be poor. In addition, the use of self-aligning ball bearings has the problems of high cost and large housing geometry.

[0006] 3) The worm gear is cantilever-supported, with a deep groove ball bearing at one end and the other end suspended. The worm gear is prone to radial runout during operation, which causes a significant torque change during steering operation, resulting in a poor operating experience for the driver.

[0007] It is desirable to provide an improved automobile steering reducer, particularly with respect to improving the driver's operating experience and reducing the noise generated during operation. Summary of the invention

[0008] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a steering reducer for an automobile, the purpose of which is to reduce the noise generated during the working process.

[0009] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: an automobile steering reducer, including a reducer housing, a worm, a worm wheel assembly and a bearing seat assembly, the bearing seat assembly is installed on the worm through a first bearing, the bearing seat assembly includes a bearing seat body and an elastic element arranged on the bearing seat body, the elastic element is in contact with the inner circular surface of the reducer housing, a second bearing is arranged on the worm, and a mounting hole for accommodating the worm and a bearing hole for accommodating the second bearing are arranged in the reducer housing, and there is a certain vertical distance between the axis of the mounting hole and the axis of the bearing hole.

[0010] The bearing seat body is provided with a seat hole for accommodating the first bearing and a mounting groove for accommodating the elastic element. The seat hole and the outer ring of the first bearing are in interference fit, and the inner ring of the first bearing and the worm are in interference fit.

[0011] A second bearing is arranged on the worm, the worm is connected with a coupling, and the coupling is fitted with an inner ring end surface of the second bearing.

[0012] The second bearing is a four-point contact ball bearing.

[0013] A bearing pressure plate is arranged in the reducer housing, and the bearing pressure plate is in contact with the outer ring end surface of the second bearing. The bearing pressure plate is arranged to press the outer ring of the second bearing onto the reducer housing.

[0014] The worm gear assembly comprises a worm gear core and a worm wheel arranged on the worm gear core, the worm wheel is meshed with the worm, the worm gear core is installed on the gear shaft, and the gear shaft is provided with a third bearing and a fourth bearing.

[0015] The third bearing is a four-point contact ball bearing.

[0016] A portion of the third bearing is located inside the reducer housing, and another portion of the third bearing is located outside the reducer housing.

[0017] The fourth bearing is a deep groove ball bearing, and the fourth bearing is installed in the end cover, and the end cover is fixedly connected to the reducer housing.

[0018] The present invention also provides an assembly process for an automobile steering reducer, comprising the steps of:

[0019] S1. Install the fourth bearing in the end cover to form an end cover assembly;

[0020] S2. Install the third bearing in the reducer housing to form a first reducer housing assembly;

[0021] S3, installing the worm gear assembly on the gear shaft to form a gear shaft assembly;

[0022] S4, installing the gear shaft assembly in the first reducer housing assembly to form a second reducer housing assembly;

[0023] S5, installing the second bearing on the worm to form a first worm assembly;

[0024] S6, installing the coupling on the worm assembly to form a second worm assembly;

[0025] S7, installing the second worm assembly in the second reducer housing assembly, and then installing the bearing pressure plate in the reducer housing, the bearing pressure plate presses the outer ring of the second bearing, to form a third reducer housing assembly;

[0026] S8, installing the first bearing and the elastic element on the bearing seat body to form a bearing seat assembly;

[0027] S9. Install the bearing seat assembly in the third reducer housing assembly, and the inner ring of the first bearing is subjected to the pressing force;

[0028] S10, installing the plug on the reducer housing to form a fourth reducer housing assembly;

[0029] S11. Install the end cover assembly in the fourth reducer housing assembly.

[0030] The automobile steering reducer of the present invention arranges an elastic element on the bearing seat and arranges the mounting hole as an eccentric hole. The elastic element always generates a force to make the worm close to the worm wheel, thereby ensuring that noise caused by a large meshing gap between the worm wheel and the worm will not occur, reducing the noise generated during the operation of the reducer and improving the driver's operating experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] This specification includes the following drawings, which show the following contents:

[0032] Figure 1 The internal structure of the automobile steering reducer of the present invention is shown in FIG. Figure 1 ;

[0033] Figure 2 The internal structure of the automobile steering reducer of the present invention is shown in FIG. Figure 2 ;

[0034] Figure 3 The internal structure of the automobile steering reducer of the present invention is shown in FIG. Figure 3 ;

[0035] Figure 4 The external structure of the automobile steering reducer of the present invention is shown in FIG. Figure 1 ;

[0036] Figure 5 The external structure of the automobile steering reducer of the present invention is shown in FIG. Figure 2 ;

[0037] Figure 6 is a cross-sectional view of the bearing housing assembly;

[0038] The markings in the figure are: 1. elastic element; 2. plug; 3. bearing seat body; 4. first bearing; 5. worm; 6. worm wheel; 7. second bearing; 8. bearing pressure plate; 9. coupling; 10. first bolt; 11. fourth bearing; 12. end cover; 13. worm wheel core; 14. third bearing; 15. shaft retaining ring; 16. gear shaft; 17. second bolt; 18. reducer housing; 19. first mounting part; 20. second mounting part. DETAILED DESCRIPTION

[0039] The specific implementation methods of the present invention are further explained in detail below by describing the embodiments with reference to the accompanying drawings, with the aim of helping those skilled in the art to have a more complete, accurate and in-depth understanding of the concept and technical solution of the present invention and facilitating its implementation.

[0040] It should be noted that, in the following embodiments, the "first", "second", "third" and "fourth" do not represent an absolute distinction in structure and / or function, nor do they represent a sequence of execution, but are merely for the convenience of description.

[0041] like Figures 1 to 6 As shown, the present invention provides an automobile steering reducer, including a reducer housing 18, a worm 5, a worm wheel assembly and a bearing seat assembly. The bearing seat assembly is installed on the worm through a first bearing 4. The bearing seat assembly includes a bearing seat body 3 and an elastic element 1 arranged on the bearing seat body 3. The elastic element 1 contacts the inner circular surface of the reducer housing 18. The elastic element 1 is a circular ring structure. The elastic element 1 has elastic properties. The elastic element 1 always generates a force to make the worm 5 close to the worm wheel 6, thereby ensuring that noise caused by a large meshing gap between the worm and the worm wheel will not occur, reducing the noise generated during the operation of the reducer, and improving the driver's operating experience.

[0042] Specifically, if Figure 1 and Figure 6 As shown, the bearing seat body 3 is provided with a seat hole for accommodating the first bearing 4 and a mounting groove for accommodating the elastic element 1, the seat hole and the outer ring of the first bearing 4 are interference fit, and the inner ring of the first bearing 4 and the worm are interference fit.

[0043] Preferably, the first bearing 4 is a deep groove ball bearing, which is installed in a manner in which the outer ring and the inner ring are tightly fitted, and does not bear axial load. Therefore, the bearing will not generate noise that causes a poor steering experience for the driver during operation.

[0044] like Figure 1 and Figure 6 As shown, the bearing seat body 3 includes a first mounting portion 19 and a second mounting portion 20 connected to each other. The first mounting portion 19 and the second mounting portion 20 are coaxially arranged. A seat hole for accommodating the first bearing 4 is arranged on the first mounting portion 19. A mounting groove is arranged on the outer circumferential surface of the second mounting portion 20. The mounting groove is an annular groove extending along the entire circumference on the outer circumferential surface of the second mounting portion 20. The elastic element 1 is sleeved on the second mounting portion 20 and embedded in the mounting groove. The elastic element 1 is an elastic rubber ring. The elastic element 1 contacts the inner circumferential surface of the reducer housing 18, and the worm is inserted into the center hole of the second mounting portion 20.

[0045] like Figure 1 As shown, the worm 5 is provided with a second bearing 7, and a bearing hole matched with the second bearing 7 is provided in the reducer housing 18, and the bearing hole is matched with the outer ring of the second bearing 7 in a clearance manner. One end of the worm 5 is connected to the coupling 9, and the coupling 9 is fitted with the inner ring end face of the second bearing 7. The coupling 9 is used to connect with the motor of the electric power steering system of the automobile. The torque of the motor is transmitted to the worm 5 through the coupling 9, and the torque is amplified through the worm gear assembly and then transmitted to the gear shaft 16 to achieve the function of reducing speed and increasing torque. The first bearing 4 is located at the other end of the worm 5, and the worm 5 is supported by the first bearing 4 and the second bearing 7. A bearing pressure plate 8 is provided in the reducer housing 18, and the bearing pressure plate 8 is fitted with the outer ring end face of the second bearing 7. The bearing pressure plate 8 is configured to press the outer ring of the second bearing 7 against the reducer housing 18.

[0046] Preferably, the second bearing 7 is a four-point contact ball bearing that can bear axial loads. The bearing is installed in a loose outer ring and tight inner ring manner. The inner ring of the second bearing 7 is pressed against the worm 5 through a coupling 9, and the outer ring of the second bearing 7 is pressed against the reducer housing 18 through a bearing pressure plate 8 and a first bolt 10. The second bearing 7 has no axial movement, so the bearing will not generate noise that causes poor steering experience for the driver during operation. The first bolt 10 is a hexagonal bolt, two of which are provided, and a through hole for the first bolt 10 to pass through is provided on the bearing pressure plate 8.

[0047] like Figure 1 As shown, the outer ring of the second bearing 7 is pressed onto the reducer housing 18 using a bearing pressure plate 8 and two first bolts 10 , and the thickness of the outer ring of the second bearing 7 is greater than the depth of the bearing hole on the reducer housing 18 .

[0048] like Figure 1 As shown, a plug 2 is installed at the small end of the worm hole of the reducer housing 18, and the plug 2 is threadedly connected to the reducer housing 18. An O-ring groove is provided on the plug 2, and an O-ring can be installed for sealing as needed.

[0049] like Figure 2 As shown, the worm gear assembly includes a worm gear core 13 and a worm wheel 6 arranged on the worm gear core 13, the worm wheel 6 is meshed with the worm 5, the worm gear core 13 is mounted on the gear shaft 16, and the gear shaft 16 is provided with a third bearing 14 and a fourth bearing 11. The worm wheel 6 is injection molded on the worm gear core 13, and the two are combined into one to form a worm gear assembly. The worm gear assembly is mounted on the gear shaft 16 through the worm gear core 13, and the worm gear core 13 and the gear shaft 16 are interference fit to form a gear shaft assembly. The gear shaft assembly is mounted on the reducer housing assembly, which is a clearance fit. The gear shaft assembly is riveted to the third bearing 14 through the shaft retaining ring 15, and the shaft retaining ring 15 is sleeved on the gear set, and the third bearing 14 is clamped between the shaft retaining ring 15 and the worm gear core 13.

[0050] Preferably, the third bearing 14 is a four-point contact ball bearing. The third bearing 14 is mounted on the reducer housing 18, and the outer ring of the third bearing 14 and the bearing hole set on the reducer housing 18 are interference fit to form a reducer housing assembly. The third bearing 14 can withstand axial loads. The bearing adopts an installation method in which the outer ring is tightly fitted and the inner ring is loosely fitted, and the inner ring of the bearing is riveted in the axial direction with a shaft retaining ring 15, and there is no axial movement. Therefore, the bearing will not generate noise that causes poor steering experience for the driver during operation.

[0051] As a preferred example, Figure 1 As shown, a part of the third bearing 14 is located inside the reducer housing 18, and another part of the third bearing 14 is located outside the reducer housing 18. The thickness of the outer ring of the third bearing 14 is greater than the depth of the bearing hole set on the reducer housing 18. The gear shaft 16, the third bearing 14 and the bearing hole are coaxially arranged. A part of the outer ring of the third bearing 14 is located inside the bearing hole, and another part of the outer ring of the third bearing 14 is outside the bearing hole. The part of the outer ring of the third bearing 14 located outside the bearing hole is used for matching and installing the output unit, and the outer ring of the third bearing 14 can provide support for the output unit. This structural design realizes the simplification of the structure, so that the overall structure after the output unit and the reducer are assembled can be more compact, reducing the cost.

[0052] like Figure 2As shown, the fourth bearing 11 is installed in the end cover 12, and the outer ring of the fourth bearing 11 is interference fit with the bearing hole of the end cover 12 to form an end cover assembly, and the end cover 12 is fixedly connected to the reducer housing 18. The end cover assembly is installed with the reducer housing 18 through the stopper on the end cover 12, and an O-ring can be installed on the stopper of the end cover for sealing as needed.

[0053] Preferably, the fourth bearing 11 is a deep groove ball bearing, which is installed in a manner of tight fit of the outer ring and loose fit of the inner ring, and does not bear axial load. Therefore, the bearing will not generate noise that causes poor steering experience for the driver during operation.

[0054] like Figure 2 As shown, the worm wheel 6 realizes its two-end bearing support structure on the reducer housing 18 through the third bearing 14 and the fourth bearing 11, so the worm wheel 6 will not produce radial runout during operation, thereby not causing corresponding fluctuations in the driver's steering operation feel.

[0055] like Figure 1 and Figure 5 As shown, the reducer housing 18 is provided with a mounting stop A and three threaded holes B for matching and mounting various types of motors.

[0056] like Figure 1 and Figure 3 As shown, a mounting hole is provided in the reducer housing 18, and the worm 5, the bearing seat body 3 and the elastic element 1 are located in the mounting hole. The mounting hole is eccentrically arranged, and there is a certain vertical distance X between the axis of the mounting hole and the axis of the bearing hole where the second bearing 7 is located. Taking the axis of the bearing hole where the second bearing 7 is located as a reference, the axis of the mounting hole where the bearing seat body 3 is located is offset in the direction close to the worm wheel 6, and its eccentric distance is X. The distance between the axis of the mounting hole and the worm wheel 6 is smaller than the distance between the axis of the bearing hole where the second bearing 7 is located and the worm wheel 6, and the axis of the mounting hole is parallel to the axis of the bearing hole where the second bearing 7 is located. After all parts are assembled, the eccentric distance X causes the elastic element 1 to generate an elastic force that allows the worm 5 to approach the worm wheel 6, so that the worm wheel and the worm are always meshed without gap.

[0057] The elastic element 1 completely fills the eccentric circular cavity between the bearing seat body 3 and the reducer housing 18. Due to the damping effect of the elastic element 1, there will be no hardware contact in any movement direction other than the rotational movement of the worm 5, thereby avoiding the generation of metal contact and collision noise that causes a poor steering experience for the driver.

[0058] The present invention also provides an assembly process for an automobile steering reducer, comprising the following steps:

[0059] S1. Install the fourth bearing 11 in the end cover 12 to form an end cover assembly;

[0060] S2, installing the third bearing 14 in the reducer housing 18 to form a first reducer housing assembly;

[0061] S3, installing the worm gear assembly on the gear shaft 16 to form a gear shaft assembly;

[0062] S4, installing the gear shaft assembly in the first reducer housing assembly to form a second reducer housing assembly;

[0063] S5, installing the second bearing 7 on the worm to form a first worm assembly;

[0064] S6, installing the coupling 9 on the worm assembly to form a second worm assembly;

[0065] S7, installing the second worm assembly in the second reducer housing assembly, and then installing the bearing pressure plate 8 in the reducer housing 18, the bearing pressure plate 8 presses the outer ring of the second bearing 7, and forms a third reducer housing assembly;

[0066] S8, installing the first bearing 4 and the elastic element 1 on the bearing seat body 3 to form a bearing seat assembly;

[0067] S9, install the bearing seat assembly in the third reducer housing assembly, and the inner ring of the first bearing 4 is subjected to the pressing force;

[0068] S10, installing the plug 2 on the reducer housing 18 to form a fourth reducer housing assembly;

[0069] S11. Install the end cover assembly in the fourth reducer housing assembly.

[0070] In the above step S1, the fourth bearing 11 is pressed into the end cover 12, and the outer ring of the fourth bearing 11 is subjected to the pressing force to form an end cover assembly.

[0071] In the above step S2, the third bearing 14 is pressed into the reducer housing 18, and the outer ring of the third bearing 14 is subjected to the pressing force, thereby forming a first reducer housing assembly.

[0072] In the above step S3, the assembly of the worm wheel 6 and the worm wheel core 13 is pressed into the gear shaft, and the worm wheel core 13 is subjected to the pressing force to form a gear shaft assembly.

[0073] In the above step S4, the gear shaft assembly is placed into the first reducer housing assembly, and the two assemblies are riveted together using the shaft retaining ring 15, and the inner ring of the third bearing 14 is subjected to the pressing force to form the second reducer housing assembly.

[0074] In the above step S5, the second bearing 7 is pressed onto the worm 5, and the inner ring of the second bearing 7 is subjected to the pressing force, thereby forming a first worm assembly.

[0075] In the above step S6, the coupling 9 is pressed onto the first worm assembly, and the inner ring of the second bearing 7 is subjected to the pressing force, thereby forming the second worm assembly.

[0076] In the above step S7, the second worm assembly is placed into the second reducer housing assembly, the bearing pressure plate 8 is placed, and then the two first bolts 10 are installed. The bolts are tightened according to the specified torque requirements, and the bearing pressure plate 8 presses the outer ring of the second bearing 7 to form a third reducer housing assembly.

[0077] In the above step S8, the first bearing 4 is pressed into the bearing seat body 3, and then the elastic element 1 is put on to form a bearing seat assembly.

[0078] In the above step S9, the bearing seat assembly is pressed into the third reducer housing assembly, and the inner ring of the first bearing 4 is subjected to the pressing force.

[0079] In the above step S10, the plug 2 is tightened onto the reducer housing 18 to form a fourth reducer housing assembly.

[0080] In the above step S11, the end cover assembly is placed into the fourth reducer housing assembly, and three second bolts 17 are inserted to complete all assembly.

[0081] The automobile steering reducer with the above structure has a small number of parts, simple parts manufacturing, low cost and simple assembly process.

[0082] The present invention is described above by way of example in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-mentioned methods. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention; or the above concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. Automobile steering reducer, including reducer housing, worm and worm gear assembly, characterized in that: It also includes a bearing seat assembly, which is installed on the worm through a first bearing. The bearing seat assembly includes a bearing seat body and an elastic element arranged on the bearing seat body, the elastic element is in contact with the inner circular surface of the reducer housing, a second bearing is arranged on the worm, and a mounting hole for accommodating the worm and a bearing hole for accommodating the second bearing are arranged in the reducer housing, and there is a certain vertical distance between the axis of the mounting hole and the axis of the bearing hole.

2. The automobile steering reducer according to claim 1, characterized in that: The bearing seat body is provided with a seat hole for accommodating the first bearing and a mounting groove for accommodating the elastic element. The seat hole and the outer ring of the first bearing are in interference fit, and the inner ring of the first bearing and the worm are in interference fit.

3. The automobile steering reducer according to claim 1, characterized in that: The worm is connected to a coupling, and the coupling is fitted with an inner ring end surface of the second bearing.

4. The automobile steering reducer according to claim 3, characterized in that: The second bearing is a four-point contact ball bearing.

5. The automobile steering reducer according to claim 3, characterized in that: A bearing pressure plate is arranged in the reducer housing, and the bearing pressure plate is in contact with the outer ring end surface of the second bearing. The bearing pressure plate is arranged to press the outer ring of the second bearing onto the reducer housing.

6. The automobile steering reducer according to any one of claims 1 to 5, characterized in that: The worm gear assembly comprises a worm gear core and a worm wheel arranged on the worm gear core, the worm wheel is meshed with the worm, the worm gear core is installed on the gear shaft, and the gear shaft is provided with a third bearing and a fourth bearing.

7. The automobile steering reducer according to claim 6, characterized in that: The third bearing is a four-point contact ball bearing.

8. The automobile steering reducer according to claim 6, characterized in that: A portion of the third bearing is located inside the reducer housing, and another portion of the third bearing is located outside the reducer housing.

9. The automobile steering reducer according to claim 6, characterized in that: The fourth bearing is a deep groove ball bearing, and the fourth bearing is installed in the end cover, and the end cover is fixedly connected to the reducer housing.

10. The assembly process of the automobile steering reducer according to any one of claims 1 to 9, characterized in that: Includes steps: S1. Install the fourth bearing in the end cover to form an end cover assembly; S2. Install the third bearing in the reducer housing to form a first reducer housing assembly; S3, installing the worm gear assembly on the gear shaft to form a gear shaft assembly; S4, installing the gear shaft assembly in the first reducer housing assembly to form a second reducer housing assembly; S5, installing the second bearing on the worm to form a first worm assembly; S6, installing the coupling on the worm assembly to form a second worm assembly; S7, installing the second worm assembly in the second reducer housing assembly, and then installing the bearing pressure plate in the reducer housing, the bearing pressure plate presses the outer ring of the second bearing, to form a third reducer housing assembly; S8, installing the first bearing and the elastic element on the bearing seat body to form a bearing seat assembly; S9. Install the bearing seat assembly in the third reducer housing assembly, and the inner ring of the first bearing is subjected to the pressing force; S10, installing the plug on the reducer housing to form a fourth reducer housing assembly; S11. Install the end cover assembly in the fourth reducer housing assembly.

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