A large output force electric power steering gear structure

Abstract

The utility model discloses a kind of electric power steering gear structures of big output force, belong to electric power assisted steering technical field.The structure includes input unit and power unit, input unit is composed of hand force input end, gear, rack shell and rack, power unit includes motor and motor controller, worm, worm wheel, ball screw nut, ball screw and screw shell.Motor output shaft is driven worm rotation by spline coupling, worm and worm wheel meshing form speed reduction and increase torque transmission mechanism, worm wheel is coaxially connected with ball screw nut, drives ball screw to generate linear thrust, to push rack and realize vehicle steering.System is equipped with angle torque sensor and motor controller and constitutes closed loop control, realizes adaptive power adjustment based on vehicle speed and steering input.The utility model has the advantages of compact structure, large output force, high transmission efficiency and high control precision, and is suitable for electric power steering system of new energy automobile and intelligent driving vehicle.

Description

Technical Field

[0001] This utility model relates to the field of electric steering technology, specifically to an electric steering structure with high output force. Background Technology

[0002] This invention relates to the field of automotive steering system technology, and particularly to a high-output electric power steering (EPS) structure. With the rapid development of new energy vehicles and intelligent driving technology, the front axle load of vehicles is constantly increasing, placing higher demands on the output force and stability of the EPS system. Currently, common EPS systems mainly include two types of structures: rack and pinion and ball screw. The rack and pinion structure is simple, but due to limitations in tooth meshing strength and speed ratio, the output force is relatively small. While the ball screw structure has higher transmission efficiency, it often uses a motor belt drive, which limits the transmission ratio and complicates the structure, making it difficult to achieve high output force under high load conditions.

[0003] In existing belt-driven ball screw power steering systems, the torque output from the motor is transmitted to the screw nut via a belt, thereby driving the ball screw to produce power assist output. However, when a larger transmission ratio is required, the belt's meshing efficiency decreases significantly, easily leading to problems such as slippage, tooth skipping, and squealing noises, causing sluggish power assist response or even steering failure. Furthermore, belt drives suffer from rapid wear and tension decay during long-term operation, affecting the overall reliability and lifespan of the system. This type of structure is ill-suited to meet the steering requirements of electric vehicles and autonomous vehicles under high load and high torque conditions.

[0004] Furthermore, in some existing recirculating ball or ball screw type electric power steering systems, the ball screw simultaneously bears axial and radial loads. Uneven bearing stress can easily cause screw deformation, reduced system stiffness, and decreased transmission accuracy. At the same time, the complex system layout and numerous components not only limit assembly space but also increase manufacturing costs and the difficulty of noise control.

[0005] Patent document CN219969766U discloses a screw-worm gear electric power steering assembly. While this structure achieves high transmission efficiency and adaptive compensation, its worm gear mechanism and screw drive are separate components, resulting in a long transmission chain, complex structure, and poor rigidity and coaxiality. It still suffers from output response lag and high assembly precision requirements. Furthermore, the elastic element of the center distance compensation mechanism is prone to aging under long-term operation, affecting meshing stability. Patent document CN220884535U discloses a "worm gear electric power steering structure." Although this solution can improve the output torque of the steering system to some extent, its core transmission still relies on a belt structure, which is prone to problems such as whistling noise, belt skipping, and severe wear under high torque and high transmission ratios. Furthermore, belt drives are prone to tension attenuation, synchronization errors, and maintenance difficulties during long-term use, resulting in insufficient transmission stability. The applicant's earlier patent application, document number CN222793603U, proposed setting the manual force unit and the assist unit in parallel and achieving mechanical coupling through a connecting rod arm; however, its assist unit still relies on a belt-type reduction mechanism to achieve torque transmission, which limits the transmission ratio and cannot provide sufficient output force under high torque conditions. Patent document number CN222793606U sets a worm gear, helical pinion, and large helical gear to form a two-stage reduction mechanism, but the torque amplification process of this solution requires multiple stages of gear meshing, resulting in a long transmission path, high manufacturing complexity, and limitations imposed by the meshing angle and installation accuracy of the helical gears.

[0006] Patent document CN222611228U discloses an electric power steering assembly structure and vehicle, which mainly addresses the issues of environmental sealing and protection, but does not improve the output torque and transmission efficiency from the perspective of transmission structure. Its power steering mechanism still adopts the traditional gear or belt drive method. Therefore, there is an urgent need to provide an electric power steering structure with a compact structure, high transmission ratio, and large output force to replace the traditional belt drive form. Utility Model Content

[0007] The technical problem to be solved by this utility model is to overcome the existing defects and provide an electric steering gear structure with high output force. Through the innovative coaxial integrated worm gear and ball screw transmission structure, it is significantly superior to the existing technology in terms of transmission path, structural strength, noise control and intelligent power assist control. It achieves high output force, high transmission ratio and high stability, and can effectively solve the problems in the background technology.

[0008] To achieve the above objectives, this utility model provides the following technical solution: a high-output electric steering gear structure, comprising an input unit and an assist unit. The input unit includes a manual force input end, a gear, a rack housing, and a rack. The rack is disposed in the rack housing, and the gear is disposed at the lower end of the manual force input end, meshing with the rack. The assist unit includes a lead screw housing, a ball screw, a motor and a motor controller, a worm gear, and a worm. The output shaft of the motor and the motor controller is fixedly connected to the worm. The worm and the output shaft of the motor and the motor controller adopt a spline connection structure to achieve reliable torque transmission and facilitate assembly and maintenance. The worm and the worm wheel mesh with each other to form a worm gear transmission mechanism. The ball screw is disposed in the lead screw housing, and the worm wheel and the ball screw... The worm gear is coaxially arranged, with its end face firmly connected to the lead screw fixing bolt. Multiple evenly distributed worm gears are connected to the lead screw nut fixing bolt to ensure transmission concentricity and torque transmission stability. This structure can drive the ball screw nut to rotate synchronously by assisting the rotation of the worm gear. The ball screw nut and ball screw transmit motion through ball meshing, converting rotational motion into linear reciprocating motion; thus achieving power assistance. The ball screw and rack are integrally machined structures. The worm gear reduces speed and increases torque, transmitting it to the ball screw nut, and then transmits the torque through the ball screw to the ball joint to generate thrust. The ball joint pushes and pulls the wheels to achieve vehicle steering. The lead screw housing is fixedly connected to the rack housing with bolts, reducing intermediate transmission connection links and improving system rigidity and response speed.

[0009] Furthermore, an angle and torque sensor is installed on the hand force input end. The angle and torque sensor is electrically connected to the motor and motor controller. The angle and torque sensor detects the rotation angle and torque signal of the hand force input end and transmits the signal to the motor and motor controller. The motor and motor controller control the motor to output the corresponding assist torque according to the vehicle speed signal and steering input signal. The torque output is reduced and increased through the worm gear transmission mechanism to drive the ball screw nut to generate thrust. The motor controller and the angle and torque sensor form a closed-loop control system. The motor controller adjusts the motor output current in real time according to the steering input signal and vehicle speed signal to achieve adaptive assist control.

[0010] Furthermore, a lead screw positioning bearing is provided in the rack housing. The lead screw positioning bearing is a double-row angular contact ball bearing. The lead screw positioning bearing can withstand axial force and radial force at the same time, ensuring the stability of the ball screw transmission. The inner ring of the lead screw positioning bearing is fastened to the end of the lead screw through the positioning bearing fastening stud, and its outer ring is embedded in the rack housing.

[0011] Furthermore, a sealing ring is provided between the lead screw housing and the rack housing to seal the connection between the housings and prevent oil leakage.

[0012] Furthermore, the lead screw housing and rack housing are made of aluminum alloy or magnesium alloy to reduce overall weight and improve heat dissipation.

[0013] Compared with the prior art, the beneficial effects of this utility model are: 1. This invention achieves an integrated design of worm gear and ball screw transmission by arranging the worm wheel and ball screw nut coaxially. The motor output torque, after being reduced and amplified by the worm and worm wheel, directly drives the ball screw nut to generate thrust. This design significantly simplifies the transmission chain, eliminates the influence of multi-stage bearings and center distance errors, resulting in a more compact structure, higher transmission rigidity, and faster response speed. The multi-point evenly distributed worm wheel and ball screw nut fixing bolt connection ensures transmission concentricity and torque transmission stability, greatly improving the system's mechanical efficiency and output capacity.

[0014] 2. A high-ratio worm gear mechanism is used to replace the traditional belt drive, utilizing the high torque-increasing characteristics of the worm gear to achieve greater output torque; the ball screw positioning bearing adopts a double-row angular contact ball bearing, which can simultaneously withstand axial and radial loads, ensuring the smoothness and high precision of the ball screw drive.

[0015] 3. The present invention is significantly superior to the prior art in terms of structural integration, transmission efficiency, output force, control precision, heat dissipation performance and system reliability, and is particularly suitable for electric steering systems of new energy vehicles, high-load and intelligent driving vehicles. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the assist unit structure of this utility model; Figure 2 This is a schematic diagram of the input unit structure of this utility model; Figure 3 This is a schematic diagram of the overall structure of this utility model.

[0017] In the diagram: 1. Hand force input end, 2. Angle and torque sensor, 3. Gear, 4. Rack housing, 5. Rack, 6. Motor and motor controller, 7. Lead screw positioning bearing, 8. Positioning bearing fastening stud, 9. Worm, 10. Worm wheel, 11. Ball screw nut, 12. Sealing ring, 13. Bolt, 14. Ball screw, 15. Lead screw fixing bolt, 16. Lead screw housing. Detailed Implementation

[0018] In the description of this utility model, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0019] Please see Figure 1-3 This utility model provides a technical solution: a high-output electric steering gear structure, including an input unit and an assist unit; the input unit includes a manual force input end 1, a gear 3, a rack housing 4, and a rack 5, with the rack 5 disposed in the rack housing 4, and the gear 3 disposed at the lower end of the manual force input end 1, meshing with the rack 5; the assist unit includes a lead screw housing 16, a ball screw 14, a motor and motor controller 6, a worm gear 10, and a worm 9, with the output shaft of the motor and motor controller 6 fixedly connected to the worm 9, and the worm 9 and the output shaft of the motor and motor controller 6 using a spline connection structure to achieve reliable torque transmission and facilitate assembly and maintenance; the worm 9 and the worm gear 10 mesh with each other to form a worm gear transmission mechanism; the ball screw 14 is disposed in the lead screw housing 16, and the worm gear 10 and the ball screw nut The worm gear 10 is coaxially arranged, with its end face fastened to the lead screw fixing bolt 15. Multiple evenly distributed worm gears and lead screw nut fixing bolts 15 ensure transmission concentricity and torque transmission stability. This structure drives the ball screw nut 11 to rotate synchronously by assisting the rotation of the worm gear 10. The ball screw nut 11 and ball screw 14 transmit motion through ball meshing, converting rotational motion into linear reciprocating motion, thus providing power assistance. The ball screw 14 and rack 5 are integrally machined. After the worm gear 10 reduces speed and increases torque, it drives the ball screw nut 11 to generate thrust, which is then transmitted to the ball joint rod via the ball screw 14 to generate thrust. The ball joint rod pushes and pulls the wheels to achieve vehicle steering. The lead screw housing 16 is fixedly connected to the rack housing 4 by bolts 13, reducing intermediate transmission links and improving system rigidity and response speed.

[0020] In another embodiment, an angle torque sensor 2 is provided on the upper part of the hand force input terminal 1. The angle torque sensor 2 is electrically connected to the motor and motor controller 6 to detect the rotation angle and torque signal of the hand force input terminal 1 and transmit the signal to the motor and motor controller 6. The motor and motor controller 6 control the motor to output the corresponding assist torque according to the vehicle speed signal and the steering input signal. The torque output is reduced and increased through the worm gear transmission mechanism to drive the ball screw nut 11 to generate thrust. The motor controller 6 and the angle torque sensor 2 form a closed-loop control system, which adjusts the motor output current in real time according to the steering input signal and the vehicle speed signal to realize adaptive assist control.

[0021] In another embodiment, a lead screw positioning bearing 7 is provided in the rack housing 4. The lead screw positioning bearing 7 is a double-row angular contact ball bearing, which can withstand axial force and radial force at the same time, thereby ensuring the stability of the ball screw 14 transmission. The inner ring of the lead screw positioning bearing 7 is fastened to the end of the lead screw through the positioning bearing fastening stud 8, and its outer ring is embedded in the rack housing 4 to achieve high-precision positioning and support.

[0022] In another embodiment, a sealing ring 12 is provided between the lead screw housing 16 and the rack housing 4 to seal the connection between the housings, prevent lubricating oil leakage, and maintain the cleanliness and stability of the lubrication environment inside the system.

[0023] In another embodiment, the lead screw housing 16 and the rack housing 4 are made of aluminum alloy or magnesium alloy to reduce the overall weight and improve heat dissipation performance, thereby improving the lightweight and thermal management capabilities of the structure.

[0024] This structure achieves a combined mechanical and electric transmission of steering force through the collaboration of the input unit and the power assist unit. The driver's hand force is transmitted via the hand force input end 1, gear 3, and rack 5 to form a primary mechanical steering signal. Simultaneously, the angle and torque sensor 2 detects the angle and torque input by the driver in real time and transmits them to the motor controller 6. The motor controller 6 calculates the required power assist based on the vehicle speed signal, controls the motor output torque, and drives the ball screw nut 11 to rotate after being reduced and increased in torque by the worm gear 9 and worm wheel 10. The ball screw nut 11 drives the ball screw 14 to generate linear thrust, realizing the power assist output to the steering mechanism. Since the ball screw 14 and rack 5 are machined as a single unit, the thrust is directly transmitted to the wheel steering structure, thereby realizing electric power steering. The screw positioning bearing 7 provides bidirectional support, ensuring that the ball screw 14 has high coaxiality and low frictional resistance during movement. The sealing ring 12 maintains the system's airtightness, preventing oil leakage and the intrusion of external impurities. The high thermal conductivity of the housing material ensures the system's heat dissipation stability and control accuracy during long-term operation.

[0025] This electric steering system features a coaxial integrated design of worm gear and ball screw, significantly simplifying the transmission chain and reducing energy loss and assembly errors. The spline connection improves torque transmission reliability and facilitates maintenance. The double-row angular contact bearing design enhances system rigidity and stability. The sealing ring structure improves sealing and protection. The lightweight alloy housing effectively reduces overall weight and improves heat dissipation. A closed-loop control system composed of an angle torque sensor and a motor controller enables adaptive power assist control, resulting in more precise steering response—lightweight at low speeds and stable at high speeds. The system is compact, has high transmission efficiency, low noise, and rapid response, making it particularly suitable for high-torque electric steering systems in new energy vehicles and intelligent driving vehicles.

[0026] In the above implementation scheme, the transmission ratio between the worm 9 and the worm wheel 10 can be designed as a single-start or multi-start structure according to the vehicle model requirements; the spline connection can be changed to a keyway or tapered sleeve structure; the connection between the screw housing 16 and the rack housing 4 can be achieved by flange, welding or locking; the ball screw nut 11 can be made of different materials (such as alloy steel, engineering plastics or composite materials) to meet the requirements of high temperature or lightweight; the torque sensor 2 can be selected as a strain gauge type, Hall type or photoelectric type structure; the sealing ring 12 can be made of fluororubber, PTFE or nitrile rubber, and can be set with double seals to enhance the sealing performance; the control algorithm can adopt fuzzy control or neural network prediction algorithm to optimize the power assist output; the housing can be further made of aluminum-magnesium composite or carbon fiber reinforced materials to improve strength and reduce weight.

[0027] This invention combines an integrated worm gear-ball screw transmission structure with intelligent power steering control to achieve an electric power steering system with high transmission ratio, high rigidity, and high responsiveness. It overcomes the shortcomings of traditional belt-type and multi-stage gear-type structures, such as low transmission efficiency, complex assembly, and insufficient output force. It has wide applicability and excellent engineering implementation value.

[0028] The foregoing has shown and described the basic principles, main features and advantages of this utility model. Various changes and modifications may be made to this utility model without departing from the spirit and scope thereof, and all such changes and modifications fall within the scope of this utility model as claimed.

Claims

1. A high-output electric steering system structure, comprising an input unit and an assist unit, characterized in that: The input unit includes a manual force input end (1), a gear (3), a rack housing (4), and a rack (5). The rack (5) is located in the rack housing (4), and the gear (3) is located at the lower end of the manual force input end (1). The gear (3) meshes with the rack (5). The assist unit includes a lead screw housing (16), a ball screw (14), a motor and motor controller (6), a worm gear (10), and a worm (9). The output shaft of the motor and motor controller (6) is connected to the worm gear (10). 9) Fixed connection: The worm (9) and worm wheel (10) mesh with each other to form a worm gear transmission mechanism; the ball screw (14) is set in the screw housing (16), the worm wheel (10) and the ball screw nut (11) are arranged coaxially, the end face of the worm wheel (10) is fastened to the screw fixing bolt (15), the ball screw (14) and the rack (5) are integrally machined structures, and the screw housing (16) is fixedly connected to the rack housing (4) by bolts (13).

2. The electric steering gear structure with high output force according to claim 1, characterized in that: An angle torque sensor (2) is provided on the hand force input end (1), and the angle torque sensor (2) is electrically connected to the motor and the motor controller (6).

3. The electric steering gear structure with high output force according to claim 1, characterized in that: A lead screw positioning bearing (7) is provided in the rack housing (4). The lead screw positioning bearing (7) is a double-row angular contact ball bearing. The inner ring of the lead screw positioning bearing (7) is fastened to the end of the lead screw through the positioning bearing fastening stud (8), and its outer ring is embedded in the rack housing (4).

4. The electric steering gear structure with high output force according to claim 1, characterized in that: A sealing ring (12) is provided between the lead screw housing (16) and the rack housing (4).

5. The electric steering gear structure with high output force according to claim 1, characterized in that: The lead screw housing (16) and rack housing (4) are made of aluminum alloy or magnesium alloy.

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