Worm and gear intermittent compensation mechanism for electric power steering system

Abstract

The utility model discloses a worm gear and worm intermittent compensation mechanism for an electric power steering system, and belongs to the technical field of automobile manufacturing. The intermittent compensation mechanism comprises a shell, a sliding block is installed in the shell, a sliding way is arranged in the shell, the sliding block is in clearance fit with the sliding way, a first magnetic block is arranged above the sliding block in the shell, a second magnetic block is arranged at the top of the sliding block, the first magnetic block and the second magnetic block are identical in magnetism, and a worm fixing assembly is arranged at the end, close to the outer side, of the sliding block. The worm fixing assembly is used for being connected with a worm. In the meshing process of the worm gear and the worm, magnetic force always exists in the clearance compensation mechanism to push the worm to the worm gear, self-adaptive compensation of the meshing clearance of the worm gear and the worm can be achieved, and the worm gear and the worm are in a good meshing state all the time. The defect that the clearance between the worm gear and the worm becomes large due to insufficient spring elasticity of a spring clearance compensation mechanism can be overcome, and grouping matching work of the worm gear and the worm and a speed reducing mechanism shell can be omitted.

Description

Technical Field

[0001] This utility model relates to the field of automobile manufacturing technology, and more specifically, to a worm gear intermittent compensation mechanism for an electric power steering system. Background Technology

[0002] With the development of intelligent driving in automobiles, electric power steering systems are widely used. Among them, the worm gear mechanism has become a common choice for the reduction mechanism of this system due to its compact structure and large reduction ratio. It reduces and increases the torque of the motor, then combines it with the driver's steering force to operate the steering actuator and achieve steering.

[0003] Currently, electric power steering systems mostly use a combination of plastic worm gears and metal worms. However, plastic worm gears have many problems: thermal expansion and water absorption lead to poor dimensional stability; the material properties make it difficult to control the machining accuracy of the gear teeth; and poor wear resistance easily accelerates wear. These problems make it difficult to control the meshing center distance when the worm gear and worm are engaged.

[0004] The existing solution involves selecting and matching worm gears and reduction housings in groups based on their meshing center distance. While this results in good meshing during initial assembly, water absorption and thermal expansion of the worm gear during operation can cause the meshing center distance to exceed the housing center distance, leading to meshing jamming and affecting the steering system's operation. Over time, tooth surface wear can cause the meshing center distance to become smaller than the housing center distance, resulting in abnormal noise during reversing and reduced driving comfort. Furthermore, this grouping and matching method has poor interchangeability and is time-consuming and labor-intensive to assemble.

[0005] Existing worm gear backlash compensation mechanisms typically employ an adjustment device at the axial outer end of the worm's driven bearing, often using a spring for backlash compensation. However, due to metal fatigue and material properties, springs undergo plastic deformation during use, resulting in non-linear spring force decay. This leads to insufficient backlash compensation force, an uneven feel, and negatively impacts the normal operation of the steering system. Therefore, there is an urgent need for a backlash compensation mechanism that does not suffer from spring force decay due to metal fatigue. In light of this, we propose an intermittent worm gear compensation mechanism for electric power steering systems. Utility Model Content

[0006] The purpose of this invention is to provide a worm gear intermittent compensation mechanism for an electric power steering system, so as to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, this utility model provides the following technical solution:

[0008] A worm gear intermittent compensation mechanism for an electric power steering system includes a housing, a slider installed inside the housing, a slide rail provided inside the housing, the slider and the slide rail being clearance-fitted, a first magnetic block being provided above the slider inside the housing, and a second magnetic block being provided on the top of the slider, the first magnetic block and the second magnetic block having the same magnetism.

[0009] The slider is located at one end of the housing near the outer side, where a worm gear fixing assembly is provided. The worm gear fixing assembly is used to connect with the worm gear.

[0010] Preferably, the worm gear fixing assembly includes a bearing outer bushing, a bearing, and a bearing bushing. The bearing outer bushing is fitted inside the housing, the outer ring of the bearing is fitted inside the inner ring of the bearing outer bushing, and the bearing bushing is fitted inside the inner ring of the bearing.

[0011] Preferably, both the first magnetic block and the second magnetic block are rectangular.

[0012] Preferably, the first and second magnetic blocks are permanent magnets.

[0013] Preferably, the bearing is a deep groove ball bearing.

[0014] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0015] In this invention, during the worm gear meshing process, a clearance compensation mechanism continuously exerts a magnetic force to push the worm towards the worm wheel, enabling adaptive compensation of the worm gear meshing clearance and ensuring the worm gear remains in a optimal meshing state. When the worm gear meshing center distance is greater than the housing center distance, the clearance compensation mechanism allows the worm gear to operate stably at a larger meshing center distance, ensuring normal meshing transmission without jamming. When the worm gear meshing center distance is less than the housing center distance, the magnetic force of the clearance compensation mechanism maintains a good meshing state between the worm and the worm wheel, preventing meshing noise. Furthermore, this clearance compensation mechanism eliminates the drawback of spring clearance compensation mechanisms where insufficient spring force leads to increased worm gear clearance. It also eliminates the need for grouping and selecting the worm gear and reduction mechanism housings, improving assembly processability and reducing product development costs. Attached Figure Description

[0016] Figure 1 This is an exploded view of the overall structure of this utility model;

[0017] Figure 2 This is a cross-sectional structural diagram of the present invention;

[0018] Figure 3 This is a cross-sectional view of the overall structure of this utility model in its working state.

[0019] The following are the labels in the diagram: 1. Housing; 2. Slider; 201. Second magnet; 3. First magnet; 4. Bearing bushing; 5. Bearing; 6. Bearing bushing; 7. Worm; 8. Worm wheel. Detailed Implementation

[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0021] Example:

[0022] Please see Figure 1-3 A worm gear intermittent compensation mechanism for an electric power steering system includes a housing 1, a slider 2 installed inside the housing 1, and a slide rail provided inside the housing 1. The slider 2 is clearance-fitted with the slide rail, ensuring that the slider 2 moves along a predetermined trajectory while allowing for self-correction of minor displacement deviations. A first magnetic block 3 is disposed above the slider 2 inside the housing 1, and the first magnetic block 3 is interference-fitted with the housing 1. A second magnetic block 201 is disposed on the top of the slider 2. The first magnetic block 3 and the second magnetic block 201 have the same magnetism; both the first magnetic block 3 and the second magnetic block 201 are rectangular and are permanent magnets. A worm gear fixing assembly is disposed at one end of the slider 2 near the outer side of the housing 1. The worm gear fixing assembly is used to connect to the end of the worm gear 7. The movement of the slider 2 directly acts on the worm gear fixing assembly, realizing dynamic compensation of the meshing clearance between the worm gear 7 and the worm wheel 8.

[0023] The housing 1 contains a mounting position and a slide for the first magnet 3. The first magnet is interference-fitted with the housing, and the slider is clearance-fitted with the slide within the housing 1. A first magnet 3 is embedded inside the housing, and a second magnet is embedded at the top of the slider 2. During the meshing process of the worm 7 and worm wheel 8, a magnetic force is consistently applied between the first magnet 3 and the second magnet, pushing the worm 7 towards the worm wheel 8. This allows for adaptive compensation of the meshing clearance between the worm wheel 8 and worm 7, ensuring that the worm wheel 8 and worm 7 are always in a good meshing state. When the meshing center distance is greater than the housing center distance, the existence of this clearance compensation mechanism allows the worm wheel 8 and worm 7 to operate stably at a larger meshing center distance. The worm 7 can mesh and transmit power normally without jamming. When the meshing center distance is less than the housing center distance, the presence of the magnetic force of the clearance compensation mechanism ensures that the worm 7 and the worm wheel 8 always maintain a good meshing state, avoiding the generation of meshing noise. Moreover, since the clearance compensation mechanism uses magnetic force instead of spring force, the magnetic force can be adjusted more easily by adjusting the magnetic strength, avoiding the problem of plastic deformation due to spring fatigue and durability. The magnetic force will always be linear, which can eliminate the disadvantage of the spring clearance compensation mechanism causing the clearance to increase due to insufficient spring force. It can also eliminate the group selection work of worm wheel 8 and worm 7, improve the assembly process, and reduce product development costs.

[0024] In this application, the worm gear fixing assembly includes a bearing outer bushing 4, a bearing 5, and a bearing bushing 6. The bearing outer bushing 4 is fitted inside the housing 1, the outer ring of the bearing 5 is fitted over the inner ring of the bearing outer bushing 4, and the bearing bushing 6 is fitted over the inner ring of the bearing 5. The bearing 5 is a deep groove ball bearing. The end of the worm gear 7 passes through the bearing bushing 6 and the hole in the middle of the slider 2.

[0025] When the worm 7 rotates, a radial force Fr is generated on the worm 7 due to the gear meshing action. This radial force Fr will cause the worm 7 to always tend to move away from the worm wheel 8. Since the first magnet 3 and the second magnet 201 have the same magnetic poles and are mutually repulsive, a magnetic force F is always applied to the worm 7 through the first magnet 3. Because the bearing outer bushing 5 and the housing 1 have a gap along the meshing direction of the worm wheel 8 and worm 7, the worm 7 can wobble in the meshing direction of the worm wheel 8 and worm 7. When the meshing center distance between the worm gear 8 and worm 7 is greater than the designed center distance, the worm 7 can deflect a small angle away from the worm gear 8. This allows the worm gear 8 and worm 7 to operate stably at a larger meshing center distance, ensuring normal meshing transmission without jamming. When the meshing center distance between the worm gear 8 and worm 7 is less than the designed center distance, the magnetic force of the clearance compensation mechanism causes the worm 7 to deflect a small angle closer to the worm gear 8. This ensures that the worm 7 always maintains a good meshing state with the worm gear 8, avoiding the generation of meshing noise.

[0026] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A worm gear intermittent compensation mechanism for an electric power steering system, characterized in that, The shell (1) is internally provided with a sliding block (2), a sliding channel is arranged inside the shell (1), the sliding block (2) is in clearance fit with the sliding channel, a first magnetic block (3) is arranged above the sliding block (2) in the shell (1), a second magnetic block (201) is arranged on the top of the sliding block (2), the first magnetic block (3) and the second magnetic block (201) are magnetically identical; The sliding block (2) is provided with a worm fixing assembly at one end close to the outer side of the shell (1), and the worm fixing assembly is used for connecting a worm (7).

2. The worm / worm-and-gear intermittent compensation mechanism for an electric power steering system according to claim 1, characterized by: The worm fixing assembly comprises a bearing outer bushing (4), a bearing (5) and a bearing bushing (6), the bearing outer bushing (4) is sleeved on the inside of the shell (1), the outer ring of the bearing (5) is sleeved on the inner ring of the bearing outer bushing (4), and the bearing bushing (6) is sleeved on the inner ring of the bearing (5).

3. The worm / worm-and-gear intermittent compensation mechanism for an electric power steering system according to claim 1, characterized in that: The first magnetic block (3) and the second magnetic block (201) are rectangular.

4. The worm / worm-and-gear intermittent compensation mechanism for an electric power steering system according to claim 1, characterized in that: The first magnetic block (3) and the second magnetic block (201) are permanent magnets.

5. The worm / worm-and-gear intermittent compensation mechanism for an electric power steering system according to claim 2, characterized in that: The bearing (5) is a deep groove ball bearing.

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