Integrated electric steering gear with safety redundancy function

Abstract

An integrated electric steering gear with a safety redundancy function is characterized in that a 4 + 2 torque angle sensor is fixed on an input shaft and a steering screw assembly and clamped through a middle shell, two worm wheels are pressed on the input shaft and the steering screw assembly in an interference mode through bearing inner rings respectively, the two worm wheels are in tooth-shaped meshing transmission with a worm respectively, and the worm is driven to rotate through a transmission shaft. The two worms are in matched transmission with the two electric control driving units through tooth profiles in the axial direction to form two sets of independent electric control units, the two electric control driving units are connected to the 4 + 2 torque angle sensor through the connecting wire harness, the input shaft and the lower end of the steering screw assembly are connected with the mechanical structure assembly through the ball screw, force transmitted by the input and electric control parts is input, and the mechanical structure assembly is connected with the steering screw assembly through the ball screw. And torque output is carried out through the mechanical structure assembly. The whole electric control unit and the transmission mechanism thereof are fully redundant, the transmission mechanism is higher in durability and strength, and the structural design is highly integrated.

Description

Technical Field

[0001] The invention relates to an integrated electric steering gear with safety redundancy function, belonging to the technical field of electric power steering gears. Background Art

[0002] With the development of electrification, intelligence and networking of commercial vehicles, the steering system has also developed to provide more abundant steering functions, and the high safety performance requirements of steering are also gradually proposed and improved. The steering system of commercial vehicles has basically transitioned from hydraulic steering to electric intelligent steering. Light trucks have begun to become popular, and the demand for electric steering systems for medium and heavy trucks is also increasing day by day; electric steering gears, as an important component of the steering system, need to take into account safety performance while meeting normal power assistance and intelligent assistance, and better serve the entire steering system and even the whole vehicle; at present, commercial vehicles are still gradually improving the safety standards based on the steering function, the chassis steering space structure layout has not made much adjustment on the basis of the hydraulic layout, and the electric speed reduction structure has insufficient bearing capacity. Under this premise, the adapted electric steering gears often do not have safety redundancy or only have partial redundancy, and the electric structure with partial redundancy is relatively large, and the compatibility between different models is poor. Therefore, a highly integrated electric steering gear assembly with safety redundancy function is developed to better meet the vehicle matching and safety performance requirements. Summary of the invention

[0003] The purpose of the present invention is to develop a steering gear assembly that can meet the safety redundancy function requirements of a commercial vehicle steering system, with full redundancy of the entire electronic control unit and its transmission mechanism, higher durability and strength of the transmission mechanism, and a highly integrated structural design. It can meet the safety redundancy requirements of commercial vehicles with different load models, and can also be well adapted to the matching requirements of the compact space of a commercial vehicle chassis.

[0004] The technical solution of the present invention is: An integrated electric steering gear with safety redundancy function comprises an upper cover, an intermediate housing, a transition plate, a 4+2 torque angle sensor, a worm gear, an electronic control drive unit, an input shaft and a steering screw assembly, and a mechanical structure assembly. The invention is characterized in that: the 4+2 torque angle sensor is fixed on the input shaft and the steering screw assembly and is positioned by the intermediate housing; two worm gears are respectively pressed on the input shaft and the steering screw assembly by interference fit of the inner ring of the bearing; the two worm gears are respectively geared with the worm through tooth meshing; the two worm gears are respectively geared with the two electronic control drive units through axial tooth matching to form two independent electronic control units; the two electronic control drive units are connected to the 4+2 torque angle sensor through a connecting harness; the lower end of the input shaft and the steering screw assembly is connected to the mechanical structure assembly through a ball screw; the force transmitted by the input and electronic control parts is output as torque through the mechanical structure assembly.

[0005] A worm A and a worm B are respectively assembled on both sides of the intermediate housing, and worm A and worm B are in different axial positions, wherein worm A and worm wheel A are tooth-matched, and worm B and worm wheel B are tooth-matched, the end of worm A is connected to the electronically controlled drive unit A, and the end of worm B is connected to the electronically controlled drive unit B.

[0006] The connection direction between the worm and the electric drive unit is that the electric drive unit A connected to the worm A and the electric drive unit B connected to the worm B can be arranged in any direction on the circumference without interfering with each other.

[0007] The iron cores in the worm gear A and the worm gear B are axially limited to each other, and there is a certain axial clearance between the toothed end faces of the worm gear A and the worm gear B to avoid mutual interference during the transmission process and affect the transmission efficiency.

[0008] The inner holes of the worm gear A and the worm gear B respectively match with the shafts in the input shaft and the steering screw assembly, and form steps to meet the requirements of radial loosening force and durability after press-fitting.

[0009] The internal shape of the intermediate housing separates the 4+2 torque angle sensor from the worm gear and the bearing, preventing the grease in the worm gear and the bearing cavity from overflowing into the sensor cavity.

[0010] A clamping position for the 4+2 torque angle sensor is provided on the inner circumference of the intermediate housing to meet the assembly limit fixation of the clamp on the 4+2 torque angle sensor; a sealing hole is provided on the circumference of the intermediate housing to meet the assembly requirements of the sensor harness assembly. In addition, the sealing hole also serves as a laser welding hole for the stator in the 4+2 torque angle sensor component.

[0011] The matching holes between the sensor harness assembly and the intermediate housing are sealed with a rubber sealing ring and fastened to the intermediate housing with bolts to meet the dust and water resistance requirements; the external part of the sensor harness assembly is connected to the electronic control drive unit A and the electronic control drive unit B respectively.

[0012] The upper cover is fastened to the intermediate housing by bolts, the intermediate housing is axially fastened to the transition plate and the housing of the mechanical part by bolts, and the intermediate housing is also fastened to the electronic control drive unit A and the electronic control drive unit B by bolts, together forming the outer shell of the entire electric steering gear.

[0013] The advantages of the present invention are: The integrated electric steering gear with safety redundancy function has a complex structure, high component integration, and two independent electronic control transmission units. It has the characteristics of high structural strength, strong durability, and system redundancy. The transmission path passes through two sets of electronic control transmission units, from the electronic control drive unit (motor + ECU integration) to the worm, the worm to the worm gear, and the worm gear to the input shaft. The two sets of electronic control transmission units on the path are independent, which can meet the situation that if any part of one set of the path fails, the other set can still provide normal power steering. In terms of structural design, the double worm gear arrangement can greatly reduce the wear of the worm gear tooth profile compared to the single worm gear arrangement. According to the use mode of the steering gear input reciprocating cycle, the double worm gear can increase the durability life by at least 50% compared to the single worm gear arrangement according to the evaluation of the wear of the worm gear tooth profile; in addition, the double worm gear structure divides the force transmitted by the electronic control drive unit equally, and each worm gear is only subject to the torque transmitted by a single electronic control drive unit. Compared with the single worm gear structure, each worm gear is only subject to half the force, and its strength will be better, the worm gear material selection will be more, the cost will be better, and it can withstand the large output torque requirements of the steering gear assembly. The integrated electric steering gear with safety redundancy function is highly integrated, the transmission mechanism is durable and strong, and it has full redundancy of the electronic control unit and its transmission mechanism, which can be adapted to various types of commercial vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural schematic diagram of the present invention; Figure 2 It is a right side view of the present invention; Figure 3 It is a schematic diagram of the cooperation between the intermediate housing, the wiring harness assembly and the sensor of the present invention; Figure 4 This is a block diagram of the electronically controlled transmission unit of the present invention.

[0015] In the figure: 1. upper cover, 2. intermediate housing, 3. 4+2 torque angle sensor, 4. bearing, 5. worm gear A, 6. worm A, 7. worm gear B, 8. worm B, 9. transition plate, 10. housing assembly, 11. input shaft and steering screw assembly, 12. steering nut assembly, 13. mechanical structure assembly, 14. steering arm shaft assembly, 15. sealing hole, 16. electronic control drive unit A, 17. electronic control drive unit B, 18. sensor harness assembly, 19. clamping position, 20. rubber sealing ring. DETAILED DESCRIPTION

[0016] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0017] See also Figure 1-4The present invention includes an upper cover 1, an intermediate shell 2, a transition plate 9, a 4+2 torque angle sensor 3, a worm gear A5, a worm gear B7, a worm A6, a worm B8, a bearing 4, an electronic control drive unit A16, an electronic control drive unit B17, a sensor harness assembly 18, an input shaft and steering screw assembly 11, and a mechanical structure assembly 13. The worm gear A5, worm gear B7, and the inner ring of the bearing 4 are sequentially press-fitted on the input shaft and the steering screw assembly 11, the worm A6 and the worm gear A5 are driven by tooth meshing, the worm A6 and the electric control drive unit A16 are driven by axial tooth matching, the worm B8 and the worm gear B7 are driven by tooth meshing, and the worm B8 and the electric control drive unit B17 are driven by axial tooth matching; the 4+2 torque angle sensor 3 is welded on the input shaft and the steering screw assembly 11, and is limited by the position on the intermediate housing 2, and the sensor harness assembly 18 connected to the 4+2 torque angle sensor 3 is respectively connected to the corresponding terminals on the electric control drive unit A16 and the electric control drive unit B17; the lower end of the input shaft and the steering screw assembly 11 is connected to the mechanical structure assembly 13 through a ball screw, and the force transmitted by the input and electric control parts is output as torque through the mechanical structure assembly 13. The mechanical structure assembly 13 is a prior art, that is, a conventional mechanical structure arrangement of the steering gear, and will not be repeated in the present invention.

[0018] The sensor harness assembly 18 needs to be connected to the 4+2 sensor 3 inside the body and the electronic control drive unit outside the body through the sealing hole 15 on the intermediate shell 2. The sensor harness assembly 18 and the sealing hole 15 are sealed with a rubber sealing ring 20 and fastened with bolts to achieve the dustproof and waterproof functional requirements of this part.

[0019] Under normal circumstances, when the input end is subjected to a certain steering force, the 4+2 torque angle sensor 3 recognizes the torque / angle signal and transmits it synchronously to the electronic control drive unit A16 and the electronic control drive unit B17 through the sensor harness assembly 18. The electronic control drive unit A16 drives the motor to assist the transmission to the worm A6 through the ECU command integrated in it. The worm A6 is meshed with the worm gear A5 and the torque is amplified according to the set speed ratio; the synchronous electronic control drive unit B17 also transmits the force to the worm B8 and the worm gear B7 in a similar way and amplifies the torque. The worm gear A5 and the worm gear B7 are both fastened to the input shaft and the steering screw assembly 11, so the torque transmitted from the electronic control drive unit A16 and the electronic control drive unit B17 acts together on the input assistance, and then is transmitted to the steering nut assembly 12 and the steering arm shaft assembly 14 in the mechanical structure assembly 13 through the steering screw to achieve the required output torque and realize the electric steering assistance.

[0020] When one electronic control unit and the transmission mechanism on its path fail, including the electronic control drive unit, worm gear and worm in the path, in this case, since the two electronic control transmission mechanisms are composed of independent components, it does not affect the transmission of the other electric power steering. The other electronic control unit can continue to transmit force to the input shaft through its transmission mechanism to achieve emergency electric power steering. The whole vehicle also identifies the failure alarm of the steering electronic control unit through signal reception and then takes effective prevention measures.

[0021] In the redundant structure arrangement, the worm gear A5 and the worm gear B7 are mutually limited in the axial direction, and are completely limited by the steering screw and bearing 4 at both ends. The inner holes of the worm gear A5 and the worm gear B7 are respectively pressed into step-type with the steering screw to limit the radial direction. The tooth material of the worm gear A5 and the worm gear B7 is generally nylon material in the steering gear industry. A certain gap is left in the tooth part of the worm gear A5 and the worm gear 7B to ensure that there will be no end face friction during the transmission process to affect the transmission efficiency. Since both electronic control units can assist, under the condition of a certain output torque, worm gear A5 and worm gear B7 only need to transmit 50% of the electric torque respectively, and the force on the tooth surface of the worm gear is only half of that transmitted by a single worm gear. Therefore, under the same material and design parameters, the double worm gear structure can transmit a larger output torque and can be applied to large output steering gears; in addition, the double worm gears are arranged independently, and the worm gear transmission can be designed into different tooth shapes according to the force requirements to meet the tooth meshing strength requirements of greater torque; during the reciprocating operation of the steering gear, the number of tooth profile wear of each tooth of the worm gear is not the same. Compared with the single worm gear structure, the double worm gear structure can effectively reduce the number of wear of each tooth, and the wear-resistant life cycle of the tooth profile can be increased by more than 50%. Therefore, this redundant structure greatly improves the output torque and service life of the worm gear transmission, which can meet the needs of electric steering gears with different outputs, and has better durability and safety performance.

Claims

1. An integrated electric steering gear with safety redundancy function, comprising an upper cover, an intermediate housing, a transition plate, a 4+2 torque angle sensor, a worm gear, an electronically controlled drive unit, an input shaft and a steering screw assembly, and a mechanical structure assembly, characterized in that: The 4+2 torque angle sensor is fixed on the input shaft and the steering screw assembly and is positioned by the intermediate housing. The two worm gears are respectively pressed on the input shaft and the steering screw assembly through the interference fit of the inner ring of the bearing. The two worm gears are respectively geared with the worm through tooth meshing transmission. The two worms are respectively geared with the two electronic control drive units through axial tooth matching transmission to form two independent electronic control units. The two electronic control drive units are connected to the 4+2 torque angle sensor through a connecting harness. The lower end of the input shaft and the steering screw assembly is connected to the mechanical structure assembly through a ball screw. The force transmitted by the input and electronic control parts is output as torque through the mechanical structure assembly.

2. The integrated electric steering gear with safety redundancy function according to claim 1, characterized in that: A worm A and a worm B are respectively assembled on both sides of the intermediate housing, and worm A and worm B are in different axial positions, wherein worm A and worm wheel A are tooth-matched, and worm B and worm wheel B are tooth-matched, the end of worm A is connected to the electronically controlled drive unit A, and the end of worm B is connected to the electronically controlled drive unit B.

3. The integrated electric steering gear with safety redundancy function according to claim 2, characterized in that: The connection direction between the worm and the electric drive unit is that the electric drive unit A connected to the worm A and the electric drive unit B connected to the worm B can be arranged in any direction on the circumference without interfering with each other.

4. The integrated electric steering gear with safety redundancy function according to claim 3, characterized in that: The iron cores in the worm gear A and the worm gear B are axially limited to each other, and there is a certain axial clearance between the toothed end faces of the worm gear A and the worm gear B to avoid mutual interference during the transmission process and affect the transmission efficiency.

5. The integrated electric steering gear with safety redundancy function according to claim 4, characterized in that: The inner holes of the worm gear A and the worm gear B respectively match with the shafts in the input shaft and the steering screw assembly, and form steps to meet the requirements of radial loosening force and durability after press-fitting.

6. An integrated electric steering gear with safety redundancy function according to any one of claims 1 to 5, characterized in that: The internal shape of the intermediate housing separates the 4+2 torque angle sensor from the worm gear and the bearing, preventing the grease in the worm gear and the bearing cavity from overflowing into the sensor cavity.

7. The integrated electric steering gear with safety redundancy function according to claim 6, characterized in that: A clamping position for the 4+2 torque angle sensor is provided on the inner circumference of the intermediate housing to meet the assembly limit fixation of the clamp on the 4+2 torque angle sensor; a sealing hole is provided on the circumference of the intermediate housing to meet the assembly requirements of the sensor harness assembly. In addition, the sealing hole also serves as a laser welding hole for the stator in the 4+2 torque angle sensor component.

8. The integrated electric steering gear with safety redundancy function according to claim 7, characterized in that: The matching holes between the sensor harness assembly and the intermediate housing are sealed with a rubber sealing ring and fastened to the intermediate housing with bolts to meet the dust and water resistance requirements; the external part of the sensor harness assembly is connected to the electronic control drive unit A and the electronic control drive unit B respectively.

9. The integrated electric steering gear with safety redundancy function according to claim 8, characterized in that: The upper cover is fastened to the intermediate housing by bolts, the intermediate housing is axially fastened to the transition plate and the housing of the mechanical part by bolts, and the intermediate housing is also fastened to the electronic control drive unit A and the electronic control drive unit B by bolts, together forming the outer shell of the entire electric steering gear.

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