Assembly structure and method for pure electric steering gear with double speed reducing mechanisms

Abstract

The invention discloses an assembling structure and method for a pure electric steering gear with double speed reducing mechanisms, and relates to the technical field of pure electric steering gear. According to the structure, a speed reducing shell and a motor controller are arranged on a steering gear shell, and a first-stage speed reducing mechanism composed of a small gear and a large gear is sequentially arranged in the speed reducing shell; one end of the worm is connected with the large gear through a transmission balance shaft, and a spring and a bearing are arranged in the transmission balance shaft to achieve radial elastic supporting and mechanical balance. The assembling method is carried out according to the sequence of the self-adaptive adjusting assembly, the worm, the transmission balance shaft, the speed reduction shell, the steering gear shell and the motor controller, and through a rotation test, the meshing clearance of the gear pair and the worm and gear pair is subjected to self-adaptive compensation by utilizing elastic deformation of a spring and a rubber element. Under the condition of a single motor, a large total transmission ratio and a large steering output torque are obtained, and meanwhile transmission stability, noise vibration performance and long-term use reliability are considered.

Description

Technical Field

[0001] This invention relates to the field of electric steering output and assembly technology, specifically to an assembly structure and method for a pure electric steering system with a dual reduction mechanism. Background Technology

[0002] Currently, commercial vehicle steering systems are gradually shifting from traditional mechanical hydraulic power steering to pure electric or electronically controlled power steering. Electric recirculating ball steering systems (also known as pure electric steering systems) integrate a motor and motor controller into the traditional recirculating ball steering system, achieving electronic power steering control. Compared to hydraulic power steering systems, they offer advantages such as energy saving, simplified structure, and ease of integration with the vehicle's electronic control system, and have been widely used in the light and medium-duty commercial vehicle sector.

[0003] In existing electric recirculating ball steering systems, the motor controller typically outputs torque directly to the steering input shaft or worm gear through a single-stage reduction mechanism. Common configurations include the motor output shaft meshing with a pair of gears, or the motor output shaft being directly connected to the worm gear, which then drives the steering output mechanism via a worm-worm gear pair. Due to the limited number of reduction stages, the transmission ratio is constrained by structural space and transmission efficiency. Furthermore, the output capacity of the matching motor and controller is limited by factors such as vehicle layout, cost, and heat dissipation. Consequently, the output steering torque of existing electric recirculating ball steering systems is generally low, typically only suitable for commercial vehicles with a gross vehicle weight of approximately 8 tons or less. They are insufficient to provide adequate steering assistance for medium- and heavy-duty commercial vehicles operating under heavy-load conditions.

[0004] On the other hand, electric recirculating ball steering systems typically incorporate gear pairs or worm gear pairs as key transmission mechanisms; due to factors such as component machining accuracy, assembly errors, and long-term wear, the gear meshing clearance and worm gear meshing clearance are prone to change during use. On the one hand, too small a meshing clearance can lead to increased transmission noise and frictional heat, and in severe cases, may cause jamming or premature failure. On the other hand, excessive meshing clearance will cause increased steering system play, noticeable knocking sounds, and poor steering wheel return performance and handling stability, seriously affecting the overall vehicle driving safety and ride comfort. To control the aforementioned meshing clearance, existing technologies often involve pre-adjustment during the assembly stage through manual adjustment, shim compensation, or selection of parts with different fit grades. Some structures also incorporate a simple pre-tightening mechanism at one end of the worm gear. However, these adjustment methods generally suffer from the following shortcomings: 1) Reliance on assembly personnel's experience leads to poor assembly consistency, which is detrimental to quality control in mass production; 2) It is difficult to take into account the combined effects of machining errors, assembly errors and long-term wear. As the usage time increases, the meshing clearance will gradually increase, requiring the steering gear to be disassembled for secondary adjustment or parts replacement, resulting in a large workload and high cost of maintenance. 3) Some structures obtain a smaller meshing clearance through rigid pre-tightening, which can easily cause local overload and abnormal wear under high load or impact load conditions, thus shortening the overall life of the machine.

[0005] Patent document CN111186478B discloses a method of sequentially arranging a cylindrical gear reduction mechanism, a planetary gear reduction mechanism, and a worm gear reduction mechanism between the power steering motor and the steering output shaft, which to some extent improves the problem of insufficient output torque in existing pure electric power steering systems in the commercial vehicle field. However, the multi-stage reduction structure has a long link, many types of parts, and a complex structure, resulting in high manufacturing and assembly costs. It does not involve a structural design for adaptive adjustment of the meshing clearance of gears and worm gears under long-term operation conditions of multi-stage transmission, and cannot solve the problems of dynamic balance and automatic compensation of meshing clearance. Patent document CN114278711A focuses on the gear combination transmission path and housing arrangement, improving torque output capability through the cooperation of cylindrical gears and planetary gears; it also suffers from the above problems.

[0006] Patent document CN214823590U discloses an assembly structure for a dual-assist mechanism in a recirculating ball steering gear. The use of dual-assistance design presents several challenges: firstly, it involves a large number of components, a complex structure, and requires significant space in the steering gear housing and vehicle layout; secondly, the two sets of assist mechanisms require precise synchronous control, making calibration and fault diagnosis difficult. Patent document CN112849263B employs a dual-motor, dual-worm gear drive worm wheel, but this patent also suffers from the aforementioned problems. Patent document CN113147887B discloses a pure electric steering system for heavy-duty commercial vehicles with safety redundancy. This system uses a "synchronous belt + planetary roller screw" reduction and transmission method, rather than a structure combining a single-stage gear reduction and a second-stage worm gear reduction. It still relies heavily on initial assembly and rigid support to ensure meshing quality, making it difficult to balance the combined effects of machining and assembly errors with life-cycle wear.

[0007] Patent document CN112572604A uses a worm gear and nut-screw structure to achieve torque output. This typically requires increasing the motor specifications or the single-stage reduction ratio to obtain torque, which can easily lead to increased motor size and decreased efficiency. Furthermore, the worm support in this patent is mostly a rigid bearing support and fixed installation structure. Control of the worm gear meshing clearance is mainly limited to initial assembly pre-tightening and maintenance adjustments, making it difficult to automatically compensate for clearance changes caused by wear throughout the entire lifespan. Patent document CN110733563A transmits motor power to the recirculating ball steering gear through a "belt drive + planetary reducer," offering relatively flexible structure. However, belt drives themselves have the risk of elastic elongation and slippage, resulting in insufficient transmission stiffness and response under high torque conditions. CN214875107U uses a belt and gears. Patent document CN201125984Y also uses a single-stage worm gear and nut without adding a front-stage gear reduction. It uses pins, bearings, and pressure cap nuts to ensure the coaxiality of the motor shaft and worm gear; however, it suffers from the aforementioned problems.

[0008] Patent document CN104527776A mainly uses a planetary reduction structure to achieve the required reduction ratio and torque matching. Its structural concept is "motor + planetary reduction + recirculating ball steering gear". When a larger output torque or a higher reduction ratio is required, it is often necessary to increase the number of planetary stars or increase the planetary reduction ratio, which leads to structural complexity and decreased efficiency. Patent document CN203318492U only discloses a single-stage worm gear reduction; there is no front-stage gear reduction; it is a conventional structure.

[0009] In addition, in order to increase output torque, some solutions attempt to simply increase the reduction ratio or select a larger power motor, but this will bring problems such as increased motor size, tight layout space, increased overall weight, increased energy consumption, and significantly increased system cost; at the same time, high reduction ratio single-stage transmission also has obvious limitations in terms of noise, efficiency and lifespan.

[0010] In summary, existing electric recirculating ball steering systems still have significant shortcomings in the following aspects: (1) Due to the limited transmission capacity of the motor and single-stage reduction mechanism, the output steering torque is too small, which is difficult to meet the high torque steering requirements of medium and heavy commercial vehicles. The use of dual power steering has two problems: firstly, the number of parts is large and the structure is complex, and the requirements for steering gear housing and vehicle layout space are high; secondly, the two power steering systems need to be precisely synchronized, making calibration and fault diagnosis difficult.

[0011] (2) The meshing clearance of gear pairs and worm gear pairs is sensitive to machining, assembly and wear. There is a lack of structure that can automatically or adaptively adjust the meshing clearance throughout the entire life cycle. After long-term use, it is easy to generate backlash, noise and vibration problems. (3) The existing schemes that control the meshing clearance by manual adjustment and rigid pre-tightening are complex to assemble, rely on manual experience, require frequent maintenance, and have limited overall reliability and economy.

[0012] Therefore, it is necessary to provide an assembly structure and method for a pure electric steering system with a dual reduction mechanism to solve the above problems. Summary of the Invention

[0013] The technical problem to be solved by the present invention is to overcome the existing defects and provide an assembly structure and method for a pure electric steering gear with a dual reduction mechanism. Under the conditions of limited motor output capacity and layout space, the output torque is effectively amplified through a reasonable dual reduction mechanism design, and the meshing clearance is automatically adjusted through a structure with elastic support and adaptive compensation function, thereby improving the output capacity, transmission stability and long-term reliability of the pure electric steering gear for commercial vehicles, reducing assembly and maintenance costs, and effectively solving the problems in the background art.

[0014] To achieve the above objectives, the present invention provides the following technical solution: an assembly structure and method for a pure electric steering gear with a dual reduction mechanism, comprising a reduction housing, a motor controller, a worm gear, a worm, and a steering gear housing. The worm gear and worm are disposed within the reduction housing and mesh with each other. One end of the worm is connected to a transmission balance shaft, one end of which has a connecting countersunk hole, and the other end has a supporting countersunk hole. The connecting countersunk hole is drively connected to one end of the worm, and the two can slide relative to each other. A balance spring is disposed between the bottom of the connecting countersunk hole and the worm. The balance spring is used to balance the radial force between the worm and the transmission balance shaft to improve transmission stability. The housing of the motor controller is connected to the reduction housing by motor fixing bolts. The output shaft is connected to gear one, and gear two is installed at one end of the transmission balance shaft. Gear two meshes with gear one. A pressure bearing is installed at the bottom of the countersunk hole, and a support spring is installed on the outside of the pressure bearing. The pressure bearing not only bears radial force but also provides rotational support, without affecting the rotation of the transmission balance shaft. The support spring abuts against the inner wall of the motor controller via a support circular plate. The support circular plate has through holes on its circumference and is fixed to the housing of the motor controller by bolts. The spring can deform axially and radially, providing radial support to the transmission balance shaft and adapting to axial force. The support spring and the balance spring keep the transmission balance shaft in a dynamic balance state, ensuring stable meshing of gear two and gear one and compensating for long-term stress. To address the wear issue between gears during operation and ensure reliable transmission, gear two and gear one form a primary reduction mechanism, while the worm gear and worm constitute a secondary reduction mechanism. This two-stage reduction amplifies the output torque to drive the commercial vehicle steering system. A mounting frustum is located at the connection end of the transmission balance shaft and the worm. Bearing two is mounted on this frustum, with a rubber sleeve between the outer ring of bearing two and the motor controller. Utilizing the principle that the rubber sleeve can undergo slight deformation, the transmission meshing clearance is adaptively adjusted via balance springs and support springs to maintain balance and ensure the stability of the secondary transmission structure. A cylindrical section is located on the reduction housing, with the worm located within it. An adaptive adjustment component is located at the other end of the worm, inside the cylindrical section. The adjustable components include an end support housing, an adaptive support slider, a bearing, and an adaptive spring. The adaptive support slider is slidably connected to the end support housing, and the adaptive spring is positioned between the side of the adaptive support slider and the end support housing, providing elastic support for the adaptive support slider. When a gap occurs during the operation of the worm gear and worm, this structure can automatically compensate for the gap between the worm gear and worm. This deformation is very small, and the deformation of the spring can adaptively adjust the meshing gap, ensuring stability during transmission. The bearing is located inside the end support housing, and one end of the worm passes through the bearing to the support hole of the adaptive support slider. A rubber washer is placed between the inner ring of the bearing and the worm, and this rubber washer can undergo slight deformation.The clearance between the worm gear and worm is adjusted using an adaptive adjustment component, and the reduction gear housing and steering gear housing are fixedly connected by bolts.

[0015] Furthermore, the end of the worm gear connected to the transmission balance shaft is designed with a convex structure, and the worm gear and the transmission balance shaft are connected by splines or keyways. An adaptive clearance is left between the convex structure of the worm gear and the transmission balance shaft. A retaining sleeve is provided on the outer side of the rubber sleeve, and the retaining sleeve is threadedly connected to the reduction housing. The retaining sleeve abuts against the reduction housing to prevent its position from sliding. An anti-loosening ring is provided on the outer side of the retaining sleeve, and the anti-loosening ring is threadedly connected to the retaining sleeve and abuts against the reduction housing. The anti-loosening ring plays the role of preventing the retaining sleeve from loosening and improving the overall structural strength.

[0016] Furthermore, the end support housing is provided with a convex rib in the circumferential direction. The convex rib increases the contact force with the cylindrical part and prevents the end support housing from rotating. A limit groove is provided inside the end support housing. The adaptive support slider is located in the limit groove and slides in contact with the limit groove. A countersunk hole is provided on the limit groove. The countersunk hole corresponds to the support hole. The diameter of the countersunk hole is larger than the diameter of the support hole. The countersunk hole leaves a gap for the radial space of the worm and does not affect the axial offset of the worm, so as to realize adaptive adjustment of the clearance.

[0017] Furthermore, a rubber washer is fitted onto the worm gear. The rubber washer can undergo slight deformation to meet the adjustment requirements of the clearance between the worm gear and the worm wheel. One end of the worm gear is tilted inward, while the other end is tilted slightly outward through the transmission balance shaft. This allows gear two to reliably contact gear one, ensuring the transmission stability of the two-stage reduction mechanism. An inner sleeve is provided between the inner ring of bearing one and the rubber washer. The inner sleeve serves to restrict bearing one. An outer bushing is provided between bearing one and the end support housing. The position of bearing one is fixed by the clamping sleeve and the inner sleeve.

[0018] Furthermore, the connection end between the reduction gear housing and the motor controller is set as the motor engagement end. The motor engagement end has a threaded hole in the circumferential direction for engaging with the motor fixing bolt. The motor controller has a cylindrical extension hole through which the motor fixing bolt passes. This structure allows the motor controller to rotate slightly relative to the reduction gear housing in the extension direction of the cylindrical extension hole.

[0019] Furthermore, a rotating pin is fixed on the motor engagement end of the reduction housing, and a positioning hole is provided on the motor controller to cooperate with the rotating pin. By inserting the rotating pin into the positioning hole and rotating the motor controller within the allowable range of the cylindrical extension hole, the meshing torque of gear two and gear one is adjusted. Then, the motor fixing bolts are tightened to complete the installation of the reduction mechanism and the initial adjustment of the meshing clearance. During long-term operation, gear two and gear one may develop a gap due to wear or other assembly reasons. This problem can be effectively solved by the adaptive adjustment component and the balance mechanism composed of the support spring and the balance spring, without the need for special maintenance and adjustment later.

[0020] When adjusting the meshing torque of gear one and gear two, the motor fixing bolt is in a loose state. The rotation center of the motor controller is restricted by the cooperation between the rotating pin and the positioning hole, and the angular position of the motor controller relative to the reduction housing is adjusted within the length range of the cylindrical extension hole.

[0021] Furthermore, gear one is set as a small gear, and gear two is set as a large gear. Gear one and gear two form a first-stage reduction mechanism with a transmission ratio i1 > 1, and the worm wheel and worm form a second-stage reduction mechanism with a transmission ratio i2 > 1. The worm wheel is connected to the steering gear output mechanism and is used to output the amplified steering torque to the steering gear output shaft or the recirculating ball mechanism. The product of the two, i1 × i2, is used to amplify the output torque of the motor controller to drive the commercial vehicle steering gear. Power output principle: The motor controller drives gear one to rotate, and the power output is sent to the worm through the first-stage reduction of gear one and gear two. Then, the power output is sent to the steering gear output mechanism through the second-stage reduction of worm and worm wheel.

[0022] Furthermore, an input shaft is provided at the upper end of the steering gear housing, an end cover is provided at the upper end of the reduction gear housing, and an output shaft is provided on the side of the steering gear housing; the steering gear body generally includes a steering gear housing, a steering screw, a nut, a steering rocker arm, a bearing, an input shaft, and an output shaft, etc. An angle sensor is provided on the input shaft, and the lower end of the input shaft is connected to the steering screw through a torsion bar. The steering screw engages with the steering arm through a nut.

[0023] Furthermore, a method for assembling a pure electric steering system with a dual reduction mechanism includes the following steps: Step 1, Assembly of the adaptive adjustment component: Install the adaptive support slider in the limiting groove of the end support housing, so that the adaptive support slider slides into the limiting groove, and place the adaptive spring between the adaptive support slider and the side wall of the limiting groove to provide elastic support for the adaptive support slider. Step 2, press the adaptive adjustment component into the reduction housing: press the outer bushing into the end support housing, then press the bearing into the outer bushing, press the inner sleeve into the inner ring of the bearing, and then press the adaptive adjustment component into the bottom of the cylindrical part of the reduction housing from the direction of the motor engagement end. Step 3: Assembly of the worm gear and the adaptive adjustment component: Fit the rubber washer onto one end of the worm gear, aligning that end with the support hole on the adaptive support slider, and insert one end of the worm gear into the support hole, so that the rubber washer is located inside the inner sleeve; Step 4: Assembly of the transmission balance shaft and balance structure: Press the bearing 2 onto the mounting platform of the transmission balance shaft, press the rubber sleeve into the reduction housing from the direction of the motor connection end; put the balance spring into the connecting countersunk hole of the transmission balance shaft, align the connecting countersunk hole with the outer end of the worm, press the transmission balance shaft in, so that one end of the worm extends into the connecting countersunk hole and abuts against the balance spring. Step 5: Assembly of the reduction gear housing and the steering gear housing: Attach the reduction gear housing containing the worm gear and adaptive adjustment components to the upper end of the steering gear housing, so that the worm gear meshes with the worm wheel inside the steering gear housing, and fix the reduction gear housing to the steering gear housing with bolts; attach the end cover to the reduction gear housing and fix it with bolts. Step Six: Assembly of the transmission balance shaft support structure: Fix the support circular plate to the housing of the motor controller with bolts, press the pressure bearing into the support countersunk hole of the transmission balance shaft, and arrange the support spring between the support circular plate and the pressure bearing, opposite to the support countersunk hole, so as to provide radial elastic support for the transmission balance shaft and allow its axial displacement. Step 7: Assembly of the motor controller and gear housing and adjustment of gear meshing: Align the positioning hole on the motor controller with the rotating pin on the gear housing, so that the motor engagement end is in contact with the motor controller. Pass the motor fixing bolt through the cylindrical extension hole on the motor controller and screw it into the threaded hole on the gear housing. When the motor fixing bolt is not fully tightened, use the cooperation between the rotating pin and the positioning hole to limit the rotation center of the motor controller. Adjust the angular position of the motor controller relative to the gear housing within the length range of the cylindrical extension hole, so that gear one and gear two reach the predetermined meshing torque. Then tighten the motor fixing bolt to complete the assembly of the reduction mechanism.

[0024] Furthermore, after completing step seven, a rotation test is conducted on the assembled pure electric steering gear. During the operation of the worm gear, worm, and gears one and two, the elastic deformation of the adaptive support slider and adaptive spring in the adaptive adjustment component, in conjunction with the elastic deformation of the balance spring and support spring on the transmission balance shaft, the rubber washer between the worm and bearing one, and the rubber sleeve between the outer ring of bearing two and the motor controller, adaptively compensates for the meshing clearance between the worm gear and worm, and between gears one and two. This automatically corrects the changes in meshing clearance caused by assembly errors and wear during long-term operation of the first and second reduction mechanisms, thereby maintaining the meshing stability of the two-stage reduction transmission process and the reliability of the steering output torque without the need for subsequent special maintenance and adjustment.

[0025] This invention integrates a primary reduction mechanism consisting of gear one and gear two with a secondary reduction mechanism consisting of a worm gear and a worm shaft. A transmission balance shaft, along with its matching connecting countersunk hole, supporting countersunk hole, balance spring, supporting spring, pressure bearing, and rubber sleeve, is introduced between the worm and gear two to form a dynamic balance support structure that runs through the two-stage reduction transmission chain. While meeting the requirements for a large overall transmission ratio and high output torque, it achieves a balance between high torque output and a compact structure on the existing recirculating ball steering platform without simply increasing the motor power or adding planetary gears or dual-assist mechanisms. This overall structural design distinguishes it from existing solutions such as single-stage worm gear, planetary reducers, or dual-motor dual-assist mechanisms.

[0026] This invention features an adaptive adjustment component at the end of the worm gear furthest from the transmission balance shaft. Through the cooperation of components such as the end support housing, limiting groove, adaptive support slider, adaptive spring, bearing, and rubber washer, the worm gear achieves controlled micro-floatability at both ends in the radial and axial directions. One end warps to adjust the gear meshing state by driving the transmission balance shaft, while the other end, with the spring and rubber components, automatically compensates for the worm gear meshing clearance. This combination of "transmission balance shaft + adaptive support slider + spring + rubber elastic element" constitutes an adaptive compensation system that runs through both the first and second stage reduction mechanisms. It can automatically correct the meshing clearance during long-term operation as wear and load changes occur, maintaining smooth transmission and stable torque output. This improves upon existing structures that rely on rigid preload or manual clearance adjustment, resulting in poor assembly consistency and frequent maintenance.

[0027] This invention adds a rotating pin and a cylindrical extended hole mating structure to the motor joint end of the reduction housing, allowing the motor controller to rotate slightly around the rotating pin as the rotation center during the assembly stage. This facilitates the initial adjustment of the meshing torque between gear one and gear two. During the usage stage, it is combined with a transmission balance shaft, adaptive adjustment components, and elastic elements to achieve continuous automatic optimization of the meshing clearance, forming a coordinated adjustment mechanism of "assembly coarse adjustment + operation self-adjustment". While achieving high torque output, it avoids the problems of many parts, complex control, and difficult layout in dual-assist and dual-motor structures, reduces the dependence on assembly experience and subsequent manual clearance adjustment, and achieves a more comprehensive technical effect in terms of high torque capacity, meshing stability, NVH performance, and maintenance economy.

[0028] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention uses a first-stage reduction mechanism consisting of gear one and gear two, and a second-stage reduction mechanism consisting of a worm gear and a worm, to sequentially amplify the output torque of the motor controller, achieving a larger overall transmission ratio. This significantly improves the output torque of the steering system without significantly increasing the motor power and size, enabling the pure electric steering system to be adapted to medium and heavy-duty commercial vehicles with a larger total mass. It overcomes the shortcomings of existing single-stage reduction, planetary reduction, or dual-assist structure, which cannot meet the high torque steering requirements, and broadens the application range of electric steering systems.

[0029] 2. This invention provides a transmission balance shaft between the worm and gear two. A balance spring, a support spring, and a pressure bearing are respectively arranged in the connecting countersunk hole and the supporting countersunk hole of the transmission balance shaft. A rubber sleeve is installed between the outer ring of bearing two and the motor controller housing, forming an elastic support and radial force balance structure for the transmission balance shaft. This structure can buffer the uneven load caused by machining, assembly errors, and load changes between the motor side and the worm side, ensuring that gear one and gear two, and worm wheel and worm maintain optimal meshing during operation. This effectively reduces impact and vibration, improves transmission smoothness and overall vehicle NVH performance, and enhances the working reliability of the two-stage reduction mechanism.

[0030] 3. Through the combination of end support housing, adaptive support slider, adaptive spring, bearing one, limit groove, countersunk hole and other structures, combined with the rubber gasket arranged between the worm and bearing one, the end of the worm has a controlled micro-float capability in the axial and radial directions. When the meshing clearance changes due to wear during long-term operation of the worm gear and gear pair, the adaptive adjustment component and elastic element can automatically generate micro-displacement and deformation to continuously compensate for the meshing clearance, thereby maintaining a suitable meshing clearance throughout the entire life cycle, avoiding frequent disassembly and readjustment, and significantly reducing maintenance workload and maintenance costs.

[0031] 4. By setting a rotating pin, threaded hole, and cylindrical extension hole at the motor connection end of the reduction housing, the motor controller can make a slight rotation around the rotating pin during the assembly stage, facilitating the initial adjustment of the meshing torque of gear one and gear two. This forms a coordinated adjustment mechanism of "coarse adjustment during assembly and fine adjustment during operation" with the aforementioned balance spring, adaptive spring, and rubber parts. Structurally, this invention introduces only one motor assembly, one two-stage reduction mechanism, and one adaptive compensation structure running through both ends, based on the traditional recirculating ball steering platform. By integrating the reduction housing and steering housing, the motor controller, first-stage gear pair, second-stage worm gear pair, adaptive adjustment components, and transmission balance shaft are compactly integrated within a limited space. Compared to the dual-assist structure requiring two sets of motors and two sets of worm gear mechanisms, this invention uses a single motor and a single two-stage reduction scheme to meet high torque output requirements. The number of parts is relatively small, the housing structure is more compact, and it is easier to arrange within limited spaces such as the frame longitudinal beams, reducing system weight and cost. At the same time, it reduces the complexity of multi-motor synchronous control, calibration, and fault diagnosis in multi-assist systems, which is beneficial to improving the overall reliability and safety of the vehicle steering system. 5. The assembly method of this invention organically connects the assembly relationships between the adaptive adjustment component, worm gear, transmission balance shaft, reduction housing and steering gear housing, and motor controller through a clear step-by-step assembly sequence. On the one hand, by utilizing the cooperation between the rotating pin and the cylindrical extension hole, the motor controller can easily and precisely coarsely adjust the meshing torque of gear one and gear two during the assembly stage, reducing the reliance on the experience of assembly personnel and improving assembly consistency and efficiency. On the other hand, the balance spring, support spring, rubber washer and rubber sleeve are pre-installed simultaneously during the assembly process, so that the adaptive adjustment component, transmission balance shaft and elastic support structure can automatically participate in the adaptive correction of the meshing state during the initial operation of the whole machine. This allows the first-stage gear pair and worm gear pair to automatically approach the optimal meshing clearance after assembly error and testing, thereby reducing the disassembly, debugging and maintenance work caused by changes in meshing clearance in the later stage and improving the assembly reliability of the whole machine. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the overall appearance and structure of the present invention; Figure 2 This is a schematic diagram of the structure of the present invention with the deceleration housing removed; Figure 3 This is a schematic diagram of the worm gear mounting structure inside the deceleration housing of the present invention; Figure 4 This is a schematic diagram of the deceleration housing structure of the present invention; Figure 5 This is a schematic diagram of the motor controller structure of the present invention; Figure 6 This is a schematic diagram of the adaptive support slider structure of the present invention; Figure 7 This is a schematic diagram of the end support shell structure of the present invention; Figure 8 This is a front view schematic diagram of the end support shell structure of the present invention; Figure 9 This is a schematic diagram of the worm gear being installed in the cylindrical part of the present invention.

[0033] In the diagram: 1. Steering gear housing; 2. Input shaft; 3. End cover; 4. Motor controller; 5. Output shaft; 6. Reduction housing; 7. Motor fixing bolt; 8. Gear II; 9. Gear I; 10. Worm gear; 11. Worm; 12. Adaptive adjustment assembly; 13. Cylindrical part; 14. Rotary pin; 15. Motor connection end; 16. Threaded hole; 17. Cylindrical extension hole; 18. Positioning hole; 19. Adaptive support slider; 20. Adaptive spring; 21. Raised strip; 22. Support hole; 23. End support housing; 24. Limiting groove; 25. Countersunk hole; 26. Rubber washer; 27. Inner sleeve; 28. Outer bushing; 29. ​​Bearing I; 30. Bearing II; 31. Rubber outer sleeve; 32. Retaining sleeve; 33. Anti-loosening ring; 34. Connecting countersunk hole; 35. Pressure bearing; 36. Support plate; 37. Support spring; 38. Support countersunk hole; 39. Transmission balance shaft; 40. Balance spring; 41. Adaptive clearance; 42. Mounting frustum. Detailed Implementation

[0034] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "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, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0035] Please see Figure 1-9This invention provides a technical solution: an assembly structure and method for a pure electric steering gear with a dual reduction mechanism, comprising a reduction housing 6, a motor controller 4, a worm gear 10, a worm 11, and a steering gear housing 1. The worm gear 10 and the worm 11 are disposed within the reduction housing 6 and mesh with each other. One end of the worm 11 is connected to a transmission balance shaft 39. One end of the transmission balance shaft 39 is provided with a connecting countersunk hole 34, and the other end is provided with a supporting countersunk hole 38. The connecting countersunk hole 34 is drively connected to one end of the worm 11, and the two can slide relative to each other. A balance spring 40 is provided between the bottom of the connecting countersunk hole 34 and the worm 11 to balance the radial force between the worm 11 and the transmission balance shaft 39 to ensure transmission stability. The housing of the motor controller 4 is connected to the reduction housing 6 by a motor fixing bolt 7. The output shaft of the motor controller 4 is connected to a gear 9. One end of the balance shaft 39 is equipped with a second gear 8, which meshes with the first gear 9. A pressure bearing 35 is installed at the bottom of the countersunk hole 34, and a support spring 37 is installed on the outside of the pressure bearing 35. The pressure bearing 35 bears radial force and also provides rotational support without affecting the rotation of the transmission balance shaft 39. The support spring 37 abuts against the inner wall of the motor controller 4 through a support circular plate 36. The circumference of the support circular plate 36 is provided with through holes and is fixed to the housing of the motor controller 4 with bolts. The support spring 37 can deform axially and radially, providing radial support to the transmission balance shaft 39 and adapting to axial force. The support spring 37 and the balance spring 40 together keep the transmission balance shaft 39 in a dynamic balance state, ensuring stable meshing of the second gear 8 and the first gear 9, compensating for the gap caused by wear between gears during long-term operation, and ensuring reliable transmission.

[0036] Gear 8 and gear 9 together form a primary reduction mechanism, while worm gear 10 and worm 11 form a secondary reduction mechanism. The two-stage reduction amplifies the motor's output torque to drive the commercial vehicle's steering system. A mounting platform 42 is provided at the connection end between the transmission balance shaft 39 and the worm 11. A bearing 30 is mounted on the mounting platform 42, and a rubber sleeve 31 is provided between the outer ring of the bearing 30 and the motor controller 4. Utilizing the slight elastic deformation of the rubber sleeve 31, combined with the elastic action of the balance spring 40 and the support spring 37, the transmission meshing clearance is adaptively adjusted, ensuring that the transmission balance shaft 39 is in a state of mechanical balance and guaranteeing the stability of the secondary transmission structure. The motor controller 4 in this invention is an integrated assembly comprising a drive motor and its control unit, with its output shaft being the output shaft of the drive motor.

[0037] A cylindrical portion 13 is provided on the reduction housing 6, and the worm gear 11 is located in the cylindrical portion 13. An adaptive adjustment component 12 is provided at the other end of the worm gear 11, and the adaptive adjustment component 12 is located at the inner end of the cylindrical portion 13. The adaptive adjustment component 12 includes an end support housing 23, an adaptive support slider 19, a bearing 29, and an adaptive spring 20. The adaptive support slider 19 is slidably connected to the end support housing 23, and the adaptive spring 20 is disposed between the side of the adaptive support slider 19 and the end support housing 23 to provide elastic support for the adaptive support slider 19. When the meshing clearance between the worm wheel 10 and the worm gear 11 changes during operation, the elastic deformation of the adaptive support slider 19 and the adaptive spring 20 automatically compensates for the clearance between the worm wheel 10 and the worm gear 11.

[0038] Bearing 29 is installed inside the end support housing 23. One end of the worm 11 passes through bearing 29 and extends into the support hole 22 of the adaptive support slider 19. A rubber washer 26 is provided between the inner ring of bearing 29 and the worm 11. The rubber washer 26 can undergo slight elastic deformation, which, together with the adaptive adjustment component 12, enables fine adjustment of the gap between the worm wheel 10 and the worm 11. The reduction housing 6 and the steering housing 1 are fixedly connected by bolts.

[0039] In the above embodiment, the motor controller 4 drives its output shaft to rotate under the command of the vehicle control system. The gear 9 on the output shaft meshes with the gear 8 at one end of the transmission balance shaft 39 to achieve first-stage reduction. The torque output by the gear 8 is transmitted to the worm 11 connected to it via the transmission balance shaft 39. The worm 11 meshes with the worm wheel 10 to form a second-stage reduction mechanism, which further amplifies the torque and reduces the speed. Finally, the torque is output to the steering output mechanism (such as a steering screw, recirculating ball mechanism, etc.) through the worm wheel 10 to drive the vehicle steering mechanism. During the power transmission process, the worm 11 and the transmission balance shaft 39 will experience slight deflection and displacement under the radial and axial forces generated by the gear meshing and the worm wheel meshing. The balance spring 40 in the countersunk hole 34 applies an elastic preload to one end of the worm 11, so that the worm 11 and the transmission balance shaft 39 form a floating connection that can slide relative to each other and has an elastic preload, thereby offsetting part of the eccentric load and reducing the radial force imbalance. The pressure bearing 35 at the bottom of the countersunk hole 34 and the support spring 37 on its outer side are connected by a support circle. Plate 36 is connected to the housing of motor controller 4, providing radial elastic support for transmission balance shaft 39 and allowing it to generate controlled axial displacement, so that transmission balance shaft 39 is in a dynamic balance state in both radial and axial directions; bearing 2 30 cooperates with rubber sleeve 31, allowing a very small relative offset between transmission balance shaft 39 and motor controller 4, using the elasticity of rubber sleeve 31 to filter high-frequency vibration and local impact load, thereby maintaining stable meshing between gear 1 9 and gear 2 8; at the other end of worm 11, the adaptive adjustment component 12, through the combination of end support housing 23, adaptive support slider 19, adaptive spring 20 and bearing 1 29, allows the end of worm 11 to have a small floating space in the axial and radial directions; during operation, when the meshing clearance between worm wheel 10 and worm 11 changes due to machining errors, assembly deviations or wear, the adaptive support slider 19 undergoes a small displacement under the action of adaptive spring 20, and in conjunction with the elastic deformation of rubber washer 26, automatically changes the position of worm 11 relative to worm wheel 10, realizing adaptive compensation for worm wheel and worm meshing clearance.

[0040] Through the power transmission path of "motor controller 4 - gear 1 9 - gear 2 8 - transmission balance shaft 39 - worm 11 - worm wheel 10 - steering gear output mechanism" and the elastic support and adaptive adjustment mechanism set at both ends, the present invention achieves a large overall transmission ratio while keeping the meshing state of the first-stage gear pair and the second-stage worm gear pair within a reasonable range throughout the entire service life.

[0041] This implementation significantly improves the overall transmission ratio without significantly increasing motor power and size by connecting a first-stage gear reduction mechanism and a second-stage worm gear reduction mechanism in series between the motor controller 4 and the worm 11. This enables the pure electric steering system to meet the large steering torque requirements of medium and heavy-duty commercial vehicles. The elastic support and radial force balance structure formed by the transmission balance shaft 39, balance spring 40, support spring 37, pressure bearing 35, and rubber sleeve 31 effectively reduces off-center loading and meshing impact caused by assembly errors and load fluctuations, improves the meshing quality of gear 9 and gear 8, reduces noise and vibration, and improves the overall NVH performance and the lifespan of the reduction mechanism. The adaptive adjustment component 12 and rubber washer 26 enable the end of the worm 11 to have controlled floating capability, which can automatically fine-tune the meshing position according to the wear of the worm wheel 10, worm 11, and gear pair, and achieve continuous compensation for meshing clearance. This avoids obvious backlash, knocking noise, and steering lag after long-term operation, thereby reducing the cost of disassembly, clearance adjustment, and maintenance, and improving the long-term reliability of the pure electric steering system.

[0042] The overall structure only requires a single motor, a single set of two-stage reduction mechanism and a set of adaptive compensation mechanism to meet the requirements of high torque output and high reliability. Compared with dual-assist or multi-stage planetary reduction schemes, it has fewer parts and a more compact structure, which is beneficial for vehicle layout and cost control.

[0043] In the above embodiments, gear 9 and gear 8 can be designed as spur gears or helical gears according to specific transmission ratio requirements, or gear combinations with different modules and tooth widths can be selected according to noise and efficiency requirements; the tooth profile of worm gear 10 and worm 11 can adopt conventional structures such as involute worm or Archimedes worm, as long as the required two-stage reduction ratio can be achieved; the stiffness and preload of balance spring 40 and support spring 37 can be designed and adjusted according to the maximum steering load, expected life and meshing clearance control range of the target vehicle, or springs with different cross-sectional forms (such as round wire springs, rectangular wire springs) or combined spring structures can be used; the materials of rubber washer 26 and rubber jacket 31 can be selected from elastomer materials with different hardness and formulations according to working temperature, medium environment and durability requirements, or can be replaced with other polymer materials with similar elasticity and damping characteristics.

[0044] The cross-sectional shape and size of the transmission balance shaft 39 can be appropriately changed according to space constraints and strength requirements, as long as one end is reliably connected to gear 2 8 and the other end is connected to worm 11, and can still form an elastic support and adaptive balance structure with the cooperation of balance spring 40, support spring 37 and pressure bearing 35; the structure of the end support housing 23 in the adaptive adjustment component 12 can also be modified according to the shape of the cylindrical part 13, for example, changing the integral structure to a split type or flange connection type, to adapt to different housing processing and assembly methods.

[0045] Furthermore, without altering the basic technical concept of this invention, the specifications and models of bearing 29 and bearing 30, such as the cross-sectional form of the self-aligning bearing and the adaptive support slider 19, can be equivalently replaced according to the requirements of different vehicle models for steering load, space layout, and cost.

[0046] In one possible implementation, the end of the worm gear 11 connected to the transmission balance shaft 39 is configured with a convex structure. The worm gear 11 and the transmission balance shaft 39 are connected by a spline or keyway, and an adaptive clearance 41 is left between the convex structure of the worm gear 11 and the transmission balance shaft 39. A retaining sleeve 32 is fitted on the outer side of the rubber sleeve 31 of the outer ring of the bearing 2 30. The retaining sleeve 32 is threaded to the reduction housing 6. The retaining sleeve 32 axially presses the rubber sleeve 31 against the reduction housing 6, preventing the rubber sleeve 31 from sliding during operation. An anti-loosening ring 33 is fitted on the outer side of the retaining sleeve 32. The anti-loosening ring 33 is threaded to the retaining sleeve 32 and abuts against the outer wall of the reduction housing 6 to prevent the retaining sleeve 32 from loosening, thereby improving the overall structural strength and reliability. The convex end structure and the spline or keyway connection form a reliable torque transmission link between the worm gear 11 and the transmission balance shaft 39, while retaining an adaptive clearance at the connection. 41 allows for minimal relative displacement between the worm gear 11 and the transmission balance shaft 39 in both the radial and axial directions. Under the combined action of the balance spring 40, support spring 37, and adaptive adjustment assembly 12, this adaptive clearance 41 provides additional compensation space during changes in meshing load and wear, preventing meshing impact and local overload caused by rigid connections. The rubber sleeve 31 acts as an elastic transition medium between the bearing 30 and the motor controller 4, absorbing vibration and impact loads during torque transmission. The retaining sleeve 32 is reliably connected to the reduction housing 6 via threads, locking the axial position of the rubber sleeve 31 and constraining it radially, making its elastic deformation more controlled. The anti-loosening ring 33, through its threaded engagement with the retaining sleeve 32 and its end face contacting the reduction housing 6, prevents the retaining sleeve 32 from loosening under long-term vibration and temperature change conditions, ensuring stable operation of the rubber sleeve 31 and the bearing 30.

[0047] By adopting a convex end with spline or keyway connection, the torsional resistance and alignment between the worm gear 11 and the transmission balance shaft 39 are improved, avoiding increased transmission backlash due to loose key connection or spline wear; the adaptive clearance 41 provides a certain degree of flexibility at the connection, which is beneficial for absorbing installation deviations and deflection during operation, further improving the meshing stability of the two-stage reduction mechanism.

[0048] The combined structure of the retaining sleeve 32 and the anti-loosening ring 33 provides axial and anti-loosening dual constraints on the rubber sleeve 31, ensuring that the rubber sleeve 31 maintains a stable working position under long-term high-frequency vibration and temperature cycling environment, preventing abnormal displacement between the bearing 30 and the motor controller 4, thereby improving the overall strength and durability of the transmission balance shaft 39 support structure and reducing maintenance requirements.

[0049] In this embodiment, in addition to splines and keyways, the connection between the worm gear 11 and the transmission balance shaft 39 can also be achieved through multi-key connections, tapered fit with key connections, etc., depending on the torque magnitude and processing conditions, as long as reliable transmission is guaranteed and the adaptive clearance 41 for compensation is retained. The specific geometry of the convex structure can be designed as a frustum of a cone, a spherical end, or a cylindrical end face with chamfers to improve assembly guidance and the rationality of contact stress distribution. In addition to threaded connections, the connection between the retaining sleeve 32 and the reduction housing 6 can also adopt a snap ring locking structure or a composite form of threaded connection with anti-loosening washers. The anti-loosening ring 33 can also be replaced with a locking nut with a radial locking structure or an anti-loosening component with a plastic deformation locking structure to adapt to different assembly processes and cost requirements. Under the premise of ensuring that the rubber sleeve 31 is reliably axially compressed and anti-loosened.

[0050] In one possible implementation, the end support housing 23 is provided with a plurality of axially extending protrusions 21 in the circumferential direction. The protrusions 21 increase the contact force between the end support housing 23 and the cylindrical part 13, preventing the end support housing 23 from rotating within the cylindrical part 13. A limiting groove 24 is provided inside the end support housing 23, and the adaptive support slider 19 is located in the limiting groove 24 and slides in contact with the side wall of the limiting groove 24. A countersunk hole 25 is provided on the limiting groove 24, which corresponds axially to the support hole 22 on the adaptive support slider 19. The diameter of the countersunk hole 25 is larger than the diameter of the support hole 22, which reserves a certain gap for the worm 11 in the radial position at that location. This ensures that the worm 11 has a certain amount of room for movement in the radial direction without affecting the axial offset of the worm 11, thereby realizing the adaptive adjustment of the meshing clearance.

[0051] In the above embodiments, the protrusion 21 improves the anti-rotation capability of the end support housing 23 in the cylindrical part 13 by interference or tight fit with the inner wall of the cylindrical part 13 of the deceleration housing 6, so as to ensure that the sliding direction of the adaptive support slider 19 is consistent with the meshing force direction of the worm 11, and avoid the end support housing 23 from rotating with the worm torque, thereby ensuring the working direction and accuracy of the adaptive adjustment component 12.

[0052] The limiting groove 24 provides a guiding constraint to the adaptive support slider 19, allowing it to only perform linear reciprocating micro-movements in a predetermined direction. The adaptive spring 20 provides elastic preload between the limiting groove 24 and the adaptive support slider 19. The countersunk hole 25 is located outside the support hole 22, and its diameter is larger than that of the support hole 22, so that when the worm 11 extends into the adaptive support slider 19 through the support hole 22, the section near the countersunk hole 25 has a certain radial movement space. When the meshing clearance between the worm wheel 10 and the worm 11 changes due to load variations or wear, the worm 11 can generate a micro-displacement within the radial clearance range provided by the countersunk hole 25, without being constrained by the meshing surface of the end support housing 23. This, in conjunction with the sliding of the adaptive support slider 19, achieves adaptive compensation for the meshing clearance of the worm wheel and worm.

[0053] By circumferentially arranging protrusions 21 on the end support housing 23, rotation of the end support housing 23 within the cylindrical portion 13 is effectively prevented, ensuring stable movement of the adaptive support slider 19 along a predetermined direction and improving the working stability and reliability of the adaptive adjustment assembly 12. The fit between the limiting groove 24 and the adaptive support slider 19 balances guidance and low friction, facilitating continuous and flexible pre-tensioning of the worm 11 by the adaptive spring 20. The coaxial arrangement of the countersunk hole 25 and the support hole 22 allows the worm 11 to have controllable radial freedom near the end, avoiding local stress concentration and meshing noise caused by rigid over-constraint, while ensuring that the axial position of the worm 11 is not adversely affected. This enables fine adjustment of the worm gear meshing clearance, improving the meshing stability and noise control performance of the entire machine during long-term operation.

[0054] The number and cross-sectional shape of the protrusions 21 can be adjusted according to the inner diameter of the cylindrical part 13 and the processing technology. For example, three or four evenly distributed straight protrusions can be used, or wavy or sawtooth anti-rotation ribs can be used to improve the anti-rotation effect and assembly guidance. The end support housing 23 and the cylindrical part 13 can also be connected by key, spline or pin anti-rotation to replace the protrusion structure 21, as long as it can effectively prevent the end support housing 23 from rotating relative to the deceleration housing 6.

[0055] The shape of the limiting groove 24 can be adjusted to a rectangular groove, dovetail groove or other structure according to the cross section of the adaptive support slider 19 to improve the guiding accuracy or load-bearing capacity; the diameter and depth of the countersunk hole 25 can also be designed according to the maximum expected deflection of the worm gear 11 and the meshing clearance compensation range to ensure that appropriate adaptive adjustment capability can be obtained under different vehicle models and working conditions.

[0056] In one possible implementation, a rubber washer 26 is fitted onto the worm gear 11. The rubber washer 26 can undergo slight deformation to meet the requirements of adjusting the clearance between the worm gear 11 and the worm wheel 10. One end of the worm gear 11 is slightly tilted towards the inside of the housing, while the other end of the worm gear 11 is slightly tilted outward through the transmission balance shaft 39, so that gear 28 and gear 19 form reliable contact in the axial and radial directions, ensuring the overall transmission stability of the two-stage reduction mechanism. An inner sleeve 27 is provided between the inner ring of bearing 129 and the rubber washer 26, and the inner sleeve 27 restricts the position of bearing 129 in the axial and radial directions. An outer bushing 28 is provided between bearing 129 and the end support housing 23. By pressing the outer bushing 28 and the inner sleeve 27 together, the position of bearing 129 is reliably fixed.

[0057] In this embodiment, the rubber washer 26 serves as an elastic transition element between the worm 11 and the bearing 29. Through its slight radial and axial deformation, it absorbs the minute displacements and vibrations generated by the worm 11 under load, making the change in the meshing clearance between the worm wheel 10 and the worm 11 more gradual and controllable. When the meshing clearance between the worm wheel 10 and the worm 11 is too large due to wear or assembly deviation, the rubber washer 26 undergoes slight compression or shear deformation under the combined action of the adaptive spring 20 and the adaptive support slider 19, driving the worm 11 to move slightly towards the worm wheel 10, thereby reducing the meshing clearance.

[0058] One end of the worm 11 is slightly tilted towards the inside of the housing, and the other end is slightly tilted outward through the transmission balance shaft 39, so that the worm 11 presents a slight tilt in space. This arrangement helps to maintain a stable and sufficient meshing contact line between gear 2 8 and gear 1 9 during operation, and reduces tooth backlash fluctuation. The inner sleeve 27 and the outer bushing 28 reliably limit the bearing 1 29 in the end support housing 23, ensuring that the bearing 1 29 will not loosen or shift position during adaptive adjustment, so that the floating of the worm 11 at the end is always within a controllable range.

[0059] This embodiment, through the combination of rubber washer 26 with inner sleeve 27 and outer bushing 28, enables a flexible connection between worm 11 and bearing 29, while ensuring the stability of bearing 29's installation position. The slight warping arrangement of worm 11 improves the load distribution and meshing contact state between the first-stage gear pair and the second-stage worm gear pair, which helps reduce tooth surface contact stress and meshing noise, and improves transmission smoothness. Through the above structure, the meshing clearance changes caused by wear and installation deviations of worm gear 10, worm 11, gear 9, and gear 8 during long-term operation can be compensated more smoothly and continuously, reducing sensitivity to assembly accuracy and further improving the reliability and service life of the two-stage reduction mechanism.

[0060] The rubber gasket 26 can be made of rubber or other elastic materials with different hardness and aging resistance, such as fluororubber, nitrile rubber, thermoplastic elastomers, etc., depending on the working temperature, load and environmental medium. It can also adopt a multi-layer composite gasket structure to obtain better damping and elastic characteristics.

[0061] In addition to compression fitting, the inner sleeve 27 and outer bushing 28 can also be fixed by a snap ring, positioning shoulder or threaded locking structure, as long as the axial and radial positions of bearing 29 in the end support housing 23 are stable, and the worm 11 is allowed to float slightly with the cooperation of rubber washer 26. The size of the "inward tilt" and "outward tilt" angles of the worm 11 can be designed and optimized according to the overall machine structure layout and meshing requirements to achieve better transmission contact state and noise control effect.

[0062] The axial compression deformation of the rubber washer 26 and the deformation of the adaptive spring 20 are combined and limited to no greater than the upper limit of the sliding stroke of the adaptive support slider 19. The radial compression deformation of the rubber sleeve 31 is limited to no greater than the upper limit of the radial fit clearance between the bearing 20 and the motor controller 4, so that the nonlinear viscoelastic deformation of the rubber washer 26 and the rubber sleeve 31 forms a multi-field coupled adaptive compensation for the meshing clearance under the combined effects of temperature change, load change and wear accumulation.

[0063] In one possible implementation, the connection end between the reduction housing 6 and the motor controller 4 is set as the motor engagement end 15. The motor engagement end 15 has a plurality of threaded holes 16 in the circumferential direction that mate with the motor fixing bolts 7. The motor controller 4 is provided with a cylindrical extension hole 17 through which the motor fixing bolts 7 pass, so that the motor controller 4 can rotate slightly and adjust its position relative to the reduction housing 6 in the extension direction of the cylindrical extension hole 17.

[0064] After the motor fixing bolt 7 passes through the cylindrical extension hole 17 on the motor controller 4 and is screwed into the threaded hole 16 on the reduction housing 6, the motor controller 4 can make slight rotations and offsets around the axis of each bolt in the long hole direction of the extension hole 17 when the bolt is not fully tightened. During this process, with the rotating pin 14 cooperating with the positioning hole 18 (see claim 6) as the rotation center, the meshing position and meshing torque of gear 1 9 and gear 2 8 can be changed by adjusting the angular position of the motor controller 4 relative to the reduction housing 6. When gear 1 9 and gear 2 8 are adjusted to the predetermined meshing torque, tightening the motor fixing bolt 7 can lock the relative position of the motor controller 4 and the reduction housing 6, thereby achieving coarse adjustment of the initial meshing clearance and contact stress of the first-stage reduction mechanism.

[0065] By setting a cylindrical extension hole 17 at the motor connection end 15, the motor controller 4 is given the ability to fine adjust relative to the reduction housing 6 during the assembly stage. This allows the assembler to conveniently and intuitively adjust the meshing torque and contact pattern of gear 1 9 and gear 2 8 without having to replace shims or repeatedly disassemble and reassemble parts for trial adjustment, thus simplifying the assembly process and reducing reliance on assembly experience.

[0066] This structure, together with the support spring 37, the balance spring 40, and the adaptive adjustment component 12, constitutes an interleaved "assembly coarse adjustment + operation fine adjustment" mechanism: during the assembly stage, coarse adjustment is performed through the motor engagement end 15, and during the operation stage, fine adjustment is automatically performed by the spring and rubber elastic element, which significantly improves the meshing stability and reliability of the two-stage reduction mechanism throughout its entire life cycle.

[0067] In one possible implementation, a rotating pin 14 is fixed on the motor engagement end 15 of the reduction housing 6, and a positioning hole 18 that mates with the rotating pin 14 is provided on the motor controller 4. During assembly, the rotating pin 14 is inserted into the positioning hole 18, and the motor controller 4 is rotated within the allowable range of the cylindrical extension hole 17 to adjust the meshing torque of gear 2 8 and gear 1 9. Then, the motor fixing bolt 7 is tightened to complete the installation of the reduction mechanism and the initial adjustment of the meshing clearance. Gear 2 8 and gear 1 9 may develop a gap due to wear or other assembly reasons during long-term operation. This problem can be effectively solved by the aforementioned adaptive adjustment component 12 and the balancing mechanism consisting of the support spring 37 and the balance spring 40, without the need for special maintenance and adjustment later. When adjusting the gear meshing torque, the motor fixing bolt 7 is in a loose state. The rotation center of the motor controller 4 is limited by the cooperation between the rotating pin 14 and the positioning hole 18, and the angular position of the motor controller 4 relative to the reduction housing 6 is adjusted within the length range of the cylindrical extension hole 17.

[0068] The cylindrical extension holes 17 are arc-shaped along the circumference of the motor controller 4, so that the motor controller 4 can only rotate around the rotating pin 14 within a predetermined angle range when the motor fixing bolt 7 is not tightened. This is used to perform initial coarse adjustment of the meshing position of gear 1 9 and gear 2 8 during the assembly stage. After assembly and tightening of the motor fixing bolts 7, the change in meshing clearance between gear 1 9 and gear 2 8 is automatically compensated by the elastic deformation of the balance springs 40, support springs 37, rubber sleeves 31 at both ends of the transmission balance shaft 39, and the adaptive springs 20 and rubber washers 26 in the adaptive adjustment assembly 12, without the need to loosen the motor fixing bolts 7 again for manual adjustment.

[0069] The axial length and cross-sectional dimensions of the transmission balance shaft 39 are coordinated with the stiffness parameters of the balance spring 40 and the support spring 37, so that the transmission balance shaft 39 undergoes controlled slight deflection and axial displacement within the rated output torque range of the motor controller 4. The balance spring 40 and the support spring 37 constitute a flexible distributed support system for both ends of the transmission balance shaft 39. Under low load conditions, the transmission balance shaft 39 is constrained to remain basically coaxial with the worm 11. Under high load or impact load conditions, the transmission balance shaft 39 is allowed to make limited attitude adjustments to simultaneously improve the meshing state of gear 1 9 and gear 2 8 as well as worm wheel 10 and worm 11.

[0070] This invention manages the mechanical coupling between the primary gear pair and the secondary worm gear pair through a unified double-end elastic support structure of the transmission balance shaft 39. The transmission balance shaft 39 is not a simple force transmission component, but rather constitutes a "flexible distributed support system" through the balance spring 40, support spring 37, and rubber sleeve 31. This system automatically adjusts the posture of the transmission balance shaft 39 according to changes in the output torque of the primary reduction gear, allowing the worm 11 to obtain a dynamically updated meshing angle that changes with operating conditions. This slight change in meshing angle simultaneously reduces the lateral force at the meshing ends of gear 19 / gear 28 and brings the meshing line of the worm gear 10 / worm 11 closer to the theoretical optimal position, thereby achieving cross-level synchronous optimization. This "coupled dual-stage linkage compensation mechanism" does not exist in existing technologies, solving the problem of the previous independent and uncoordinated compensation between the primary and secondary reduction mechanisms.

[0071] The rotating pin 14 and the positioning hole 18 constitute the geometric center and guiding reference for the rotation of the motor controller 4 relative to the reduction housing 6, ensuring that the motor controller 4 rotates at a small angle around a defined rotation axis during adjustment without producing uncontrollable translation or yaw. By changing the rotation angle of the motor controller 4 around the rotating pin 14, the meshing position of gear 19 relative to gear 28 changes accordingly, thereby changing the tooth backlash and contact spot distribution and adjusting the meshing torque. During long-term operation, even if the meshing clearance between gear 19 and gear 28 gradually increases due to wear, the transmission balance shaft 39 and worm gear 11 can automatically generate a small position adjustment under the combined action of the adaptive adjustment component 12, the balance spring 40 and the support spring 37 to compensate for the meshing clearance of the gear pair and the worm gear pair, without having to loosen the motor fixing bolt 7 or readjust the position of the rotating pin 14 again.

[0072] By setting a rotating pin 14 and a positioning hole 18 at the motor connection end 15, the controllability and repeatability of the assembly and adjustment process of the motor controller 4 and the reduction housing 6 are improved, making the adjustment process of gear meshing torque simple and accurate, and significantly reducing debugging time and assembly difficulty.

[0073] Combining the aforementioned elastic balance and adaptive structure, this embodiment enables the two-stage reduction mechanism to achieve a better meshing state in the initial stage of assembly, and can automatically compensate for changes in meshing clearance through internal elastic elements throughout the entire service life, avoiding disassembly and maintenance due to gear wear or assembly errors, thereby improving the reliability and economy of the whole machine.

[0074] The rotating pin 14 can be a cylindrical pin, a tapered pin, or a locating pin with a threaded locking structure. The locating hole 18 can be set as a smooth hole, a tapered hole, or a stepped composite hole, depending on the type of pin, to adapt to different manufacturing and assembly processes. Alternatively, a double pin or pin + locating block structure can be adopted to achieve the same adjustment effect while ensuring that the rotation center is determined and assembly is convenient.

[0075] In one possible implementation, gear 9 is configured as a pinion and gear 8 as a large gear. Gear 9 and gear 8 together form a first-stage reduction mechanism with a transmission ratio i1 > 1. Worm gear 10 and worm 11 together form a second-stage reduction mechanism with a transmission ratio i2 > 1. Worm gear 10 is connected to the steering gear output mechanism and is used to output amplified steering torque to the steering gear output shaft or recirculating ball mechanism. The product of the transmission ratios of the first and second-stage reduction mechanisms, i1 × i2, is used to amplify the output torque of the motor controller 4 to drive the commercial vehicle steering gear.

[0076] The power output principle is as follows: the motor controller 4 drives the gear 9 to rotate, and the first-stage reduction output of the gear 9 and the gear 8 is sent to the worm 11, and then the second-stage reduction output of the worm 11 and the worm wheel 10 is sent to the steering gear output mechanism.

[0077] After receiving the steering command from the vehicle control system, the motor controller 4 outputs torque. First, the small gear 9 drives the large gear 8 to achieve a first-stage reduction amplification, obtaining a larger intermediate torque and reducing the speed. This torque is transmitted to the worm 11 through the transmission balance shaft 39. The worm 11 then meshes with the worm wheel 10 to form a second-stage reduction, further amplifying the output torque and further reducing the speed. Finally, the worm wheel 10 outputs the torque to the steering gear output mechanism to drive the wheels to turn.

[0078] By rationally selecting the first-stage reduction ratio i1 and the second-stage reduction ratio i2, while meeting the vehicle's steering assist requirements and response speed requirements, i1×i2 achieves the high torque amplification factor required by medium- and heavy-duty commercial vehicles, while ensuring that the motor controller 4 operates in a high-efficiency and high-reliability range.

[0079] Beneficial effects: By connecting the first-stage gear reduction and the second-stage worm gear reduction in series, this implementation method achieves a larger overall transmission ratio and output torque within a limited layout space. It does not require the use of high-power large motors or complex multiple sets of assist mechanisms, thus reducing system costs and the difficulty of vehicle layout.

[0080] The single-stage gear reduction has high transmission efficiency and good rigidity, while the two-stage worm gear reduction has good self-locking and high transmission ratio characteristics. The combination of the two ensures sufficient steering assistance while taking into account transmission efficiency and safety, making it suitable for steering systems of various medium and heavy-duty commercial vehicles.

[0081] Provided that i1>1 and i2>1 are guaranteed, the specific values ​​of the first and second reduction ratios can be optimized according to the total mass of different vehicle models, front axle load and desired steering wheel feel. For example, the first reduction ratio can be appropriately increased to reduce the load on the worm gear pair, thereby increasing the life of the worm gear pair; the second reduction ratio can also be appropriately increased to reduce the size of the gear pair and improve the compactness of the layout.

[0082] The tooth ratio, module, and tooth width of gear 9 and gear 8 can be designed according to the transmission ratio and strength requirements; worm gear 10 and worm 11 can also use different combinations of the number of heads and the number of teeth to achieve the required reduction ratio; as long as the total transmission ratio i1×i2 meets the torque requirements of the whole vehicle and is compatible with the aforementioned elastic support and adaptive compensation structure, it is within the design scope of this invention.

[0083] In one possible implementation, an input shaft 2 is provided at the upper end of the steering gear housing 1, an end cover 3 is provided at the upper end of the deceleration housing 6, and an output shaft 5 is provided on the side of the steering gear housing 1. The steering gear body includes components such as the steering gear housing 1, steering screw, nut, steering rocker arm, bearing, input shaft 2, and output shaft 5. An angle sensor is provided on the input shaft 2, and the lower end of the input shaft 2 is connected to the steering screw through a torsion bar. The steering screw is engaged with the steering arm through a nut.

[0084] The driver applies angle and torque to the input shaft 2 through the steering wheel. The angle sensor collects the angle information of the input shaft 2 in real time and transmits it to the motor controller 4. The motor controller 4 calculates the required assist torque based on the angle, vehicle operating status and control strategy, and outputs it to the steering output mechanism through the aforementioned two-stage reduction mechanism. The steering wheel is then turned from the output shaft 5 through the steering rocker arm.

[0085] The torsion bar flexibly connects the input shaft 2 to the steering screw, enabling the system to sense the torque input by the driver and generate a certain self-centering torque and road feel feedback; the pure electric power steering mechanism provides additional assistance on this basis, improving steering ease and controllability.

[0086] This embodiment integrates a pure electric dual-stage reduction assist mechanism while maintaining the mechanical structure of the traditional recirculating ball steering system. It does not change the original mechanical steering force transmission path of the vehicle. Even when the electronic control system malfunctions, it can still rely on the mechanical path to achieve basic steering functions, thereby improving system redundancy and safety. By setting an angle sensor on the input shaft 2, it can achieve deep integration with the vehicle's electronic control system, providing a foundation for realizing advanced assistance functions such as active return to center, lane keeping, and autonomous driving, thus giving the invention good scalability.

[0087] In one possible implementation, a method for assembling a pure electric steering system with a dual reduction gear includes the following steps: Step 1, Assembly of the adaptive adjustment component 12: Install the adaptive support slider 19 in the limiting groove 24 of the end support housing 23, so that the adaptive support slider 19 slides in the limiting groove 24, and place the adaptive spring 20 between the adaptive support slider 19 and the side wall of the limiting groove 24 to provide elastic support for the adaptive support slider 19. Step 2, the adaptive adjustment component 12 is pressed into the reduction housing 6: the outer bushing 28 is pressed into the end support housing 23, the bearing 29 is pressed into the outer bushing 28, the inner sleeve 27 is pressed into the inner ring of the bearing 29, and then the adaptive adjustment component 12 is pressed into the bottom of the cylindrical part 13 of the reduction housing 6 from the direction of the motor connection end 15. Step 3, assembly of worm gear 11 and adaptive adjustment component 12: fit rubber washer 26 on one end of worm gear 11, align the end with the support hole 22 on adaptive support slider 19, insert one end of worm gear 11 into support hole 22, so that rubber washer 26 is located inside inner sleeve 27. Step 4, Assembly of the transmission balance shaft 39 and the balance structure: Press the bearing 30 onto the mounting frustum 42 of the transmission balance shaft 39, press the rubber sleeve 31 into the reduction housing 6 from the direction of the motor connection end 15; place the balance spring 40 into the connecting countersunk hole 34 of the transmission balance shaft 39, align the connecting countersunk hole 34 with the outer end of the worm 11, press the transmission balance shaft 39 in, so that one end of the worm 11 extends into the connecting countersunk hole 34 and abuts against the balance spring 40; Step 5, Assembly of the reduction housing 6 and the steering housing 1: The reduction housing 6, which is equipped with the worm gear 11 and the adaptive adjustment component 12, is fastened to the upper end of the steering housing 1, so that the worm gear 11 meshes with the worm wheel 10 inside the steering housing 1, and the reduction housing 6 is fixed to the steering housing 1 with bolts; the end cover 3 is fastened to the reduction housing 6 and fixed with bolts. Step 6, Assembly of the transmission balance shaft support structure: Fix the support circular plate 36 to the housing of the motor controller 4 with bolts, press the pressure bearing 35 into the support countersunk hole 38 of the transmission balance shaft 39, and arrange the support spring 37 between the support circular plate 36 and the pressure bearing 35, and opposite to the support countersunk hole 38, thereby providing radial elastic support to the transmission balance shaft 39 and allowing its axial displacement. Step 7, Assembly of motor controller 4 and gear housing 6 and adjustment of gear meshing: Align the positioning hole 18 on motor controller 4 with the rotating pin 14 on gear housing 6, so that the motor engagement end 15 is in contact with motor controller 4. Pass motor fixing bolt 7 through the cylindrical extension hole 17 on motor controller 4 and screw it into the threaded hole 16 on gear housing 6. When motor fixing bolt 7 is not fully tightened, limit the rotation center of motor controller 4 with the cooperation of rotating pin 14 and positioning hole 18. Adjust the angular position of motor controller 4 relative to gear housing 6 within the length range of cylindrical extension hole 17. After gear 1 9 and gear 2 8 reach the predetermined meshing torque, tighten motor fixing bolt 7 to complete the assembly of the reduction mechanism.

[0088] The predetermined meshing torque can be determined through testing or calculation based on the target vehicle model, gear module, and materials, and those skilled in the art can select a suitable torque range accordingly.

[0089] When completing step seven and conducting a rotation test on the pure electric steering gear, the motor fixing bolt 7 is no longer loosened or readjusted. Instead, the steering conditions are repeatedly applied under different temperatures and steering load conditions, causing the balance springs 40, support springs 37, and rubber sleeves 31 at both ends of the transmission balance shaft 39, as well as the adaptive springs 20 and rubber washers 26 in the adaptive adjustment assembly 12, to undergo multiple minor elastic deformations and displacement iterations. This causes the meshing clearance between gear 19 and gear 28, and between worm gear 10 and worm 11 to automatically converge to the preset stable range.

[0090] Working principle: This assembly method pre-assembles the adaptive adjustment component 12, worm gear 11 and transmission balance shaft 39, and then combines them with the steering gear housing 1 and motor controller 4 in subsequent steps to accurately control the relative positional relationship between each elastic element, bearing and housing; the adaptive adjustment component 12 is assembled first and pressed into the reduction housing 6 to ensure the matching accuracy between bearing 29, adaptive support slider 19 and adaptive spring 20, and reduce the transmission of subsequent assembly errors.

[0091] By using the rotating pin 14 and the positioning hole 18 to define the rotation center of the motor controller 4 in step seven, and adjusting the angle position of the motor controller 4 within the range of the cylindrical extension hole 17, the precise coarse adjustment of the meshing torque of gear 1 9 and gear 2 8 can be achieved, laying the foundation for adaptive fine adjustment in subsequent operation.

[0092] Beneficial effects: This assembly method connects the assembly relationships between the adaptive adjustment component 12, transmission balance shaft 39, reduction housing 6, steering gear housing 1, and motor controller 4 in a clear series of steps. The assembly process is clear and easy to operate, which is conducive to ensuring assembly consistency and product quality in mass production. By pre-installing the balance spring 40, support spring 37, rubber washer 26, and rubber sleeve 31 simultaneously during the assembly process, the two-stage reduction mechanism can have adaptive compensation function on the first run, shortening the test and adjustment cycle and reducing rework and maintenance costs.

[0093] Without affecting the relative positions of the adaptive adjustment component 12, the transmission balance shaft 39 and the motor controller 4, some assembly steps can be adjusted in sequence according to the production line layout and tooling type. For example, the execution order of steps five and six can be appropriately interchanged, or some external accessories can be assembled after the deceleration housing 6 and the steering housing 1 are assembled.

[0094] The pressing method used in the assembly process can be hydraulic pressing, mechanical pressing, or threaded pressing; as long as each bearing and bushing reaches the designed preload and maintains coaxiality, the effect of this assembly method can be achieved.

[0095] In one possible implementation, a rotation test is conducted on the assembled pure electric steering gear. During the operation of the worm gear 10, worm 11, and gears 9 and 8, the elastic deformation of the adaptive support slider 19 and adaptive spring 20 in the adaptive adjustment assembly 12, in conjunction with the elastic deformation of the balance spring 40 and support spring 37 on the transmission balance shaft 39, the rubber washer 26 between the worm 11 and bearing 29, and the rubber sleeve 31 between the outer ring of bearing 30 and the motor controller 4, adaptively compensates for the meshing clearance between the worm gear 10 and worm 11, and between gear 9 and gear 8. This automatically corrects the changes in meshing clearance caused by assembly errors and wear during long-term operation of the first and second reduction mechanisms, thereby maintaining the meshing stability of the two-stage reduction transmission process and the reliability of the steering output torque without the need for subsequent special maintenance and adjustment.

[0096] During rotational testing and subsequent practical use, the meshing clearance of the worm gear 10-worm 11 pair and the gear 1-gear 2-gear 8 pair will dynamically change under periodic loads, impact loads, and wear. Under the elastic force of the adaptive spring 20, the adaptive support slider 19 will generate a small displacement according to the change in meshing force, causing the end of the worm 11 to make a slight adjustment relative to the worm gear 10. The balance spring 40 and the support spring 37 apply radial and axial elastic support to the transmission balance shaft 39, so that gear 2-gear 8 and gear 1-gear 9 still maintain a reasonable contact line in the meshing area. The rubber washer 26 and the rubber sleeve 31 provide flexible buffering in the radial and axial directions, so that the meshing impact caused by wear and load changes is partially absorbed and delayed, thereby making the meshing clearance change process smooth and controllable. Through the synergistic effect of the above elastic elements and structural components, the entire process of automatic correction and compensation of the meshing clearance can be achieved without external adjustment.

[0097] This assembly and testing method enables the pure electric steering system to complete coarse assembly adjustment and automatic fine adjustment verification during operation before leaving the factory. It can verify the working effect of the adaptive adjustment component 12 and the balance spring structure under actual working conditions. Through the adaptive compensation mechanism, it can significantly reduce the problem of excessive or insufficient meshing clearance caused by wear and assembly errors, maintain the meshing stability of the two-stage reduction transmission process and the reliability of steering output torque in the long term, reduce or avoid later disassembly, maintenance and manual clearance adjustment work, and reduce maintenance costs.

[0098] This method can also be used for production line quality control. By monitoring noise, vibration and torque fluctuations during rotation tests, it can quickly determine whether the adaptive adjustment component 12 and related elastic elements are properly assembled and functioning normally, thereby improving product consistency.

[0099] Rotation tests can be conducted under bench conditions, or after vehicle assembly, they can be conducted as road tests or bench tests simulating operating conditions. Test conditions (such as steering angle, steering speed, and load conditions) can be set according to the usage scenarios of the target vehicle model.

[0100] In addition to subjective evaluation of noise and vibration, the monitoring of meshing state can also be carried out quantitatively with torque sensors, acceleration sensors, etc., to optimize the design parameters of adaptive spring stiffness and preload. As long as the meshing clearance is automatically compensated by the adaptive adjustment component 12, spring and rubber elastic element during operation, long-term reliable meshing stability can be achieved, which is an embodiment of the present invention.

[0101] In one specific embodiment, the transmission balance shaft 39 forms a continuous force transmission path between the first-stage gear pair (gear 9 and gear 8) and the second-stage worm gear pair, and provides controlled axial and radial elastic degrees of freedom at both ends through a balance spring 40, a support spring 37, and a rubber sleeve 31, respectively. Unlike the single-point preload structure or local elastic compensation structure commonly used in the prior art, this embodiment coordinates the elastic components at both ends of the transmission balance shaft 39 to make the transmission balance shaft 39 exhibit predictable dynamic balance characteristics throughout the entire rotation cycle. When the first-stage gear pair is subjected to load and undergoes bending deformation or the second-stage worm gear pair experiences meshing eccentricity due to clearance changes, the transmission balance shaft 39 will form a slight displacement under double-end elastic constraints, thereby actively dispersing the load concentration effect between the two stages of transmission. This "cross-stage linkage balance" has not yet appeared in the prior art, and can simultaneously improve the meshing stability of the two-stage reduction mechanism, reduce noise and wear, and provide an ideal displacement window for subsequent adaptive adjustment, forming a non-simple superposition of technical synergistic effects.

[0102] In another embodiment, the adaptive adjustment component 12 is a composite structure consisting of an end support housing 23, an adaptive support slider 19, an adaptive spring 20, and a bearing 29. This structure is not only used for simple preload or clearance compensation, but also, through the combination of a limiting groove 24, a countersunk hole 25, and a support hole 22, enables the worm 11 to have controlled floating degrees of freedom in both the axial and radial directions. Unlike traditional worm gear structures that rely solely on axial preload or eccentric sleeves for unidirectional adjustment, this embodiment achieves a dynamic compensation mechanism of "dual degrees of freedom + elastic controllable stroke." Driven by the transmission balance shaft 39, the micro-displacement of the worm 11 is absorbed and guided by the adaptive adjustment component 12 in real time. The micro-elastic deformation of the adaptive spring 20 and the rubber washer 26 can simultaneously offset the clearance fluctuations between the worm wheel 10 and the worm 11 caused by wear, temperature drift, or assembly deviations, ensuring that the secondary transmission pair maintains optimal meshing for a long time. This mechanism, based on "limiting guidance +..." The "elastic floating" composite compensation method can maintain meshing stability without the need for further adjustment, which is significantly better than the local, passive, and one-time compensation methods in the prior art, and has outstanding substantive characteristics.

[0103] In another embodiment, the motor engagement end 15 of the reduction housing 6 is provided with a rotating pin 14 and a cylindrical extension hole 17 for coarse adjustment of the meshing torque of the first-stage gear pair during the assembly stage. Unlike the prior art, which relies solely on experience to manually adjust the meshing clearance and is prone to deviation, the cooperation between the rotating pin 14 and the positioning hole 18 ensures that the motor controller 4 can only rotate slightly within a preset fan-shaped trajectory, making the meshing position adjustment more precise and controllable. More importantly, the assembly adjustment structure of the present invention forms a synergistic relationship with the dynamic balance characteristics of the transmission balance shaft 39 and the elastic compensation capability of the adaptive adjustment component 12: during the assembly stage, the initial meshing position is optimized first through the rotating pin 14; if a clearance change occurs during the operation stage, the double-end elastic support of the transmission balance shaft 39 and the adaptive adjustment component 12 will automatically perform secondary compensation, realizing a dual-layer adjustment mechanism of "assembly coarse adjustment + operation adaptive fine adjustment". This synergistic effect is far superior to the method of simply relying on assembly pre-tightening or fixed value compensation in the prior art, enabling the two-stage reduction mechanism to continuously maintain meshing stability and torque output consistency throughout its entire life cycle, which has significant inventiveness.

[0104] The foregoing has shown and described the basic principles, main features and advantages of the present invention. Various changes and modifications can be made to the present invention without departing from the spirit and scope thereof, and all such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. A pure electric steering gear assembly structure with double reduction mechanism, comprising a reduction housing (6), a motor controller (4), a worm wheel (10), a worm (11) and a steering gear housing (1), characterized in that: The worm wheel (10) and the worm (11) are arranged in the reduction shell (6) and are engaged with each other, one end of the worm (11) is connected with the transmission balance shaft (39), one end of the transmission balance shaft (39) is provided with a connecting counterbore (34), the other end of the transmission balance shaft (39) is provided with a supporting counterbore (38), the connecting counterbore (34) is in transmission connection with one end of the worm (11) and can slide relative to the worm (11), the bottom of the connecting counterbore (34) and the worm (11) are provided with the balance spring (40), the shell of the motor controller (4) is connected with the reduction shell (6) through the motor fixing bolt (7), the output shaft of the motor controller (4) is connected with the gear one (9), one end of the transmission balance shaft (39) is provided with the gear two (8), the gear two (8) and the gear one (9) are engaged with each other, the bottom of the connecting counterbore (34) is provided with the pressure bearing (35), the outer side of the pressure bearing (35) is provided with the supporting spring (37), the supporting spring (37) abuts against the inner wall of the motor controller (4) through the supporting disc (36), the connecting end of the transmission balance shaft (39) and the worm (11) is provided with the mounting circular table (42), the mounting circular table (42) is provided with the bearing two (30), the outer ring of the bearing two (30) and the motor controller (4) are provided with the rubber sleeve (31), the cylindrical part (13) is arranged on the reduction shell (6), the worm (11) is located in the cylindrical part (13), the other end of the worm (11) is provided with the self-adaptive adjusting assembly (12), the self-adaptive adjusting assembly (12) comprises an end head supporting shell (23), a self-adaptive supporting sliding block (19), a bearing one (29) and a self-adaptive spring (20), the self-adaptive supporting sliding block (19) is in sliding connection with the end head supporting shell (23), the self-adaptive spring (20) is arranged between the side surface of the self-adaptive supporting sliding block (19) and the end head supporting shell (23), the bearing one (29) is arranged in the end head supporting shell (23), one end of the worm (11) passes through the bearing one (29) to the supporting hole (22) of the self-adaptive supporting sliding block (19), the inner ring of the bearing one (29) and the worm (11) are provided with the rubber washer (26), the reduction shell (6) and the steering gear shell (1) are fixedly connected through the bolt.

2. The electric power steering gear assembly with double reduction mechanism according to claim 1, characterized in that: The end of the worm (11) connected with the transmission balance shaft (39) is provided in a convex structure, the worm (11) and the transmission balance shaft (39) are connected through the spline or the key groove, the self-adaptive gap (41) is left between the convex structure of the worm (11) and the transmission balance shaft (39), the outer side of the rubber sleeve (31) is provided with the retainer (32), the retainer (32) is in threaded connection with the reduction shell (6), the outer side of the retainer (32) is provided with the lock washer (33), the lock washer (33) is in threaded connection with the retainer (32) and abuts against the reduction shell (6).

3. The electric power steering gear assembly with double reduction mechanism according to claim 1, characterized in that: The convex strip (21) is arranged in the circumferential direction of the end support shell (23), the end support shell (23) is provided with a limiting groove (24), the adaptive support slider (19) is located in the limiting groove (24) and is in sliding contact with the limiting groove (24), the limiting groove (24) is provided with a counterbore (25), the counterbore (25) corresponds to the support hole (22), and the diameter of the counterbore (25) is greater than that of the support hole (22).

4. The electric power steering gear assembly with double reduction mechanism according to claim 2 or 3, characterized in that: The rubber gasket (26) is sleeved on the worm (11), the inner ring of the bearing one (29) is provided between the rubber gasket (26) and the inner sleeve (27), the inner sleeve (27) plays a limiting role on the bearing one (29), and the bearing one (29) is provided between the end support shell (23) and the outer bushing (28).

5. The electric power steering gear assembly with double reduction mechanism according to claim 4, characterized in that: The connecting end of the reduction shell (6) and the motor controller (4) is provided as a motor joint end (15), the circumferential direction of the motor joint end (15) is provided with a threaded hole (16) for cooperating with the motor fixing bolt (7), and the motor controller (4) is provided with a cylindrical extension hole (17) through which the motor fixing bolt (7) passes.

6. The electric power steering gear assembly with double reduction mechanism according to claim 5, characterized in that: The motor joint end (15) of the reduction shell (6) is fixed with a rotating pin (14), and the motor controller (4) is provided with a positioning hole (18) matched with the rotating pin (14).

7. The electric power steering gear assembly with double reduction mechanism according to any one of claims 1-6, characterized in that: The gear one (9) is arranged as a pinion gear, the gear two (8) is arranged as a large gear, the gear one (9) and the gear two (8) constitute a transmission ratio i1>1 of a one-stage reduction mechanism, and the worm wheel (10) and the worm (11) constitute a transmission ratio i2>1 of a two-stage reduction mechanism.

8. The electric power steering gear assembly with double reduction mechanism according to claim 7, characterized in that: The upper end of the diverter shell (1) is provided with an input shaft (2), the upper end of the reduction shell (6) is provided with an end cover (3), and the side surface of the diverter shell (1) is provided with an output shaft (5).

9. A method of assembling a purely electric power steering gear with a double reduction mechanism, characterized in that, The assembly of the pure electric diverter with a double reduction mechanism comprises the following steps: Step one, assembly of the adaptive adjustment assembly (12): install the adaptive support slider (19) in the limiting groove (24) of the end support shell (23), make the adaptive support slider (19) in sliding cooperation with the limiting groove (24), and place the adaptive spring (20) between the adaptive support slider (19) and the side wall of the limiting groove (24) to provide elastic support for the adaptive support slider (19); Step two, press the adaptive adjustment assembly (12) into the reduction shell (6): press the outer bushing (28) into the end support shell (23), then press the bearing one (29) into the outer bushing (28), press the inner sleeve (27) into the inner ring of the bearing one (29), and then press the adaptive adjustment assembly (12) into the bottom of the cylindrical part (13) of the reduction shell (6) from the direction of the motor joint end (15) of the reduction shell (6); Step three: cooperative assembly of the worm (11) and the adaptive adjustment assembly (12): sleeve the rubber gasket (26) on one end of the worm (11), align the end with the support hole (22) on the adaptive support slider (19), insert one end of the worm (11) into the support hole (22), and place the rubber gasket (26) on the inner side of the inner sleeve (27). Step four: transmission balance shaft (39) and the assembly of the balance structure: bearing two (30) is pressed on the installation round table (42) of transmission balance shaft (39), and the rubber sleeve (31) is pressed into the reduction shell (6) from the motor combination end (15) direction; The balance spring (40) is put into the connecting counterbore (34) of the transmission balance shaft (39), the connecting counterbore (34) is aligned with the outer end of the worm (11), the transmission balance shaft (39) is pressed in, one end of the worm (11) is inserted into the connecting counterbore (34) and abuts with the balance spring (40); Step five: the assembly of the reduction shell (6) and the steering gear shell (1): the reduction shell (6) with the worm (11) and the self-adaptive adjustment assembly (12) is buckled on the upper end of the steering gear shell (1), the worm (11) is engaged with the worm gear (10) in the steering gear shell (1), and the reduction shell (6) is fixed with the steering gear shell (1) through bolts; The end cover (3) is buckled on the reduction shell (6) and fixed through bolts; Step six: the assembly of the transmission balance shaft support structure: the support round plate (36) is fixed on the shell of the motor controller (4) through bolts, the pressure bearing (35) is pressed into the support counterbore (38) of the transmission balance shaft (39), the support spring (37) is arranged between the support round plate (36) and the pressure bearing (35), and is opposite to the support counterbore (38), so as to provide radial elastic support for the transmission balance shaft (39) and allow its axial displacement; Step seven: the assembly of the motor controller (4) and the reduction shell (6) and the gear meshing adjustment: the positioning hole (18) on the motor controller (4) is aligned with the rotating pin (14) on the reduction shell (6), the motor combination end (15) is attached to the motor controller (4), the motor fixing bolt (7) passes through the cylindrical extension hole (17) on the motor controller (4) and is screwed into the threaded hole (16) on the reduction shell (6); When the motor fixing bolt (7) is not completely tightened, the rotating center of the motor controller (4) is limited by the cooperation of the rotating pin (14) and the positioning hole (18), the angle position of the motor controller (4) relative to the reduction shell (6) is adjusted within the length range of the cylindrical extension hole (17), the gear one (9) and the gear two (8) reach the predetermined meshing torque, and then the motor fixing bolt (7) is tightened, the assembly of the reduction mechanism is completed.

10. The method of assembling a purely electric power steering gear with a double reduction mechanism according to claim 9, characterized in that, After the completion of step seven, the assembled pure electric steering gear is subjected to a rotation test. During the operation of the worm wheel (10), the worm (11), and the gear one (9) and the gear two (8), the elastic deformation of the adaptive support slider (19) and the adaptive spring (20) in the adaptive adjustment assembly (12) is utilized to cooperate with the elastic deformation of the balance spring (40) and the support spring (37) on the transmission balance shaft (39), and the elastic deformation of the rubber washer (26) arranged between the worm (11) and the bearing one (29) and the rubber sleeve (31) arranged between the outer ring of the bearing two (30) and the motor controller (4) to adaptively compensate the meshing gap of the worm wheel (10) and the worm (11), the gear one (9) and the gear two (8); the meshing gap changes caused by the assembly error and the wear in the long-term operation of the primary reduction mechanism and the secondary reduction mechanism are automatically corrected, so that the meshing stability in the double-stage reduction transmission process and the reliability of the steering output torque are maintained without the need for special maintenance and adjustment in the later period.

Images