A compact self-aligning steering gear for steer-by-wire vehicles

Abstract

The present application relates to a kind of automobile steer-by-wire compact self-returning steering gear, including steering gear housing, rack, return spring, spring guide seat, adjusting nut, bearing bush end cover, two sides of tie rod and accessory parts, steering gear, bearing, two-stage planetary reducer and its accessory parts, motor and necessary fastener.Motor torque output, after two-stage planetary reducer deceleration and torque increase, is transmitted to steering gear, and the rotary torque of steering gear is converted into the translation lateral force of rack by gear rack way, and steering wheel is pushed around kingpin line by the tie rod of both ends to complete steering movement, realizes the basic function of steer-by-wire steering gear.The structure of the present application is simple, parts are compact, response speed is high, service life is long, mass is small, transverse and vertical space occupation is small;Its self-returning angle can reach 30 °, and considerable return force in small angle range 3-5 °, can realize complete return, greatly guarantees the driving safety of automobile.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automobile structure, and particularly relates to a compact self-return steering gear for a steer-by-wire steering system of an automobile. BACKGROUND

[0002] In recent years, four-wheel steering has attracted much attention due to its characteristics of improving the operation stability of an automobile at high speed or under the action of lateral wind, improving the steering lightness at low speed, and reducing the turning radius in a parking lot. Four-wheel steering is generally used in luxury car models, and the rear-wheel steering often uses a steer-by-wire system. The ARS active rear-wheel steering system provided in the Cadillac CT6 can reverse the rotation of the rear wheels by up to 3.5 degrees. The rear wheels of the four-wheel steering system of the Audi A7 can rotate by up to 5 degrees. The Porsche 911, Bugatti Chiron, and Lamborghini Huracan Evo all use four-wheel steering systems. With the gradual popularization of technology, the focus of rear-wheel steering has shifted from extreme maneuverability to passive safety, that is, how to return the wheels to the original position when the rear-wheel steering system fails.

[0003] Some people have proposed that the overall redundancy backup of the steer-by-wire system serves as a guarantee for passive safety, but this solution is costly and occupies a large space. Some people have proposed that the maximum steering angle of the rear wheels be limited to 3-5 degrees to indirectly ensure a certain maneuverability of the vehicle in a failure state, but this solution does not really solve the complete maneuverability of the vehicle in a failure state, and may result in a change in the characteristics of the automobile and the driver's steering feeling. Some people have proposed using double-sided external springs to drive the rack to return to the original position, but this solution has the external springs outside the steering gear housing, which is heavy and occupies a large space, and cannot achieve self-return in a small angle range.

[0004] Therefore, the self-return mechanism of mechanical design has become an important solution to the problem and can also break through the major bottleneck of large-angle rear-wheel steering (about 30 degrees) at low speed.

[0005] Patent 201410230984.2 (publication number CN104210535A) discloses a displacement detection device of a linear motion mechanism capable of being easily mounted on a rod portion of the linear motion mechanism and having a rod portion rotation stopping device function, and a rear-wheel steering device having the displacement detection device and being easy to assemble and capable of reducing costs. The mechanism well integrates the linear motor and the steering gear, so that the steering gear is small in size, but does not have a self-return mechanism to ensure automatic return in a failure state of the steer-by-wire system.

[0006] A rear wheel steering and returning mechanism for a commercial vehicle is disclosed in Chinese patent CN104960568A, which comprises a hydraulic returning cylinder and a motor, a rear wheel steering gear, a steering rocker arm and a rear wheel steering drag link connected in sequence. The motor and the rear wheel steering gear are fixed on a vehicle frame crossbeam. An upper steering knuckle arm of a rear wheel steering drive axle is connected with the rear wheel steering drag link to drive the rear wheel steering. A lower steering knuckle arm of the rear wheel steering drive axle is connected with a piston rod of the hydraulic returning cylinder to drive the rear wheel returning. The patent uses a wire control hydraulic device to assist the rear wheel steering and returning, but cannot guarantee the automatic returning in the wire control failure state.

[0007] A double-curved air bag steering and returning mechanism is disclosed in Chinese patent CN213948561U, which comprises a double-curved air bag, a connecting plate, a returning arm, a fixed support and an adjustable limiting mechanism. The double-curved air bag steering and returning mechanism can solve the problem of short stroke of a single-curved air bag, and can improve the returning force through structure optimization. Compared with an oil cylinder structure, the mechanism has a fixed buffering effect and is low in cost. However, the mechanism cannot be well integrated in a sealed steering gear, and a block will protrude longitudinally in the middle of a laterally arranged steering gear, which will affect the arrangement of the steering gear on a vehicle frame.

[0008] A rear wheel steering device is disclosed in Chinese patent CN207580062U, which comprises a vehicle body, a mounting seat, a connecting seat, vehicle rear wheels symmetrically and rotatably connected to both sides of the mounting seat, and a connecting shaft for connecting the mounting seat and the connecting seat. The rear wheel steering device has certain buffering when the rear wheels are steered, is stable in steering, and has good damping effect. However, the device is large in size, poor in returning effect, and cannot guarantee the automatic returning in a small steering angle. SUMMARY

[0009] The present application aims to overcome the defects of the prior art and provides a compact self-returning steering gear for a vehicle wire control steering, which can be arranged in a vehicle steering gear to enable a steering rack to return to zero position in a wire control failure state, only a small number of components are changed, the volume of the steering gear is not particularly increased, the steering gear is easy to assemble, and the cost is relatively low, and finally a self-returning steering gear assembly is formed.

[0010] The object of the present application can be achieved by the following technical solutions.

[0011] A compact self-returning steering gear for a vehicle wire control steering is installed on a vehicle chassis, which comprises a reducer device, a steering motor, a gear and rack transmission device, a steering gear support and wrapping device, a self-returning device and two lateral drag links and connecting devices thereof.

[0012] The reducer device is internally provided with a double-stage planetary gear reducer.

[0013] The turning motor is located outside the speed reducer device and connected with the speed reducer device, and a communication cable attached to the turning motor is electrically connected with the electronic control unit of the automobile.

[0014] The rack and pinion transmission device is arranged in the steering gear housing and comprises a steering gear, a ball bearing, a rack and a rack pressing mechanism. The rack and pinion transmission device converts the rotary motion of the steering gear into the linear motion of the rack. The rack pressing mechanism comprises a rack pressing block, a pressing spring and a pressing adjusting nut. The rack pressing mechanism pushes the pressing spring by adjusting the pressing adjusting nut assembled on the steering gear housing, so that the rack pressing block generates a set axial force, thereby ensuring the normal operation of the rack and pinion transmission device and offsetting the deformation caused by the internal force.

[0015] The steering gear support and wrapping device is arranged on both sides of the steering gear housing and comprises a sealing ring, a bearing bush end cover and a wavy sealing rubber.

[0016] The self-returning device comprises a steering gear housing, a rack, a guide spring pad, a returning spring, a rack adjusting nut, a housing adjusting nut and a locking screw. The steering gear housing is connected with the suspension mechanism supporting the front wheel or the rear wheel of the vehicle. The guide spring pad is arranged on both sides of the returning spring. The guide spring pad and the returning spring are sleeved on the right end of the rack. The returning spring compression amount is adjusted by the rack adjusting nut, and the locking screw is locked.

[0017] The two-side transverse link and the connecting device thereof comprise a plurality of rod end bearings and a plurality of steering transverse links. The steering transverse link is connected with the rod end bearing and rotates or tilts around the spherical bearing center line of the rod end bearing. The rod end bearing arranged on the outer side of the steering transverse link is used to connect the steering point on the wheel-side upright column.

[0018] Further, the right side of the rack is provided with a characteristic shoulder, an external thread area, a first limiting step, a first smooth friction area and a first internal thread hole. The right side of the rack is provided with a tooth-shaped area, a V-shaped groove, a second limiting step, a second smooth friction area and a second internal thread hole.

[0019] The diameter of the shoulder is greater than the diameter of the rest of the rack. The external thread area is a fine thread, which is used to ensure self-locking under the condition of oil lubrication. The step is the starting position of the external thread area, which limits the transverse position of the steering gear.

[0020] The first smooth friction area and the second smooth friction area are respectively inserted into the round holes in the centers of the first bearing bush end cover and the second bearing bush end cover on both sides of the steering gear housing.

[0021] The rod end bearing and the U-shaped joint are connected with the two-side steering transverse links through the first internal thread hole and the second internal thread hole, respectively.

[0022] Further, the diverter housing body is composed of a transverse large cylinder, a transverse small cylinder, a longitudinal cylinder, a vertical cylinder and a four-corner connecting ring.

[0023] Further, the transverse large cylinder is provided with a step on the left side, and a smooth inner wall on the right side of the step;

[0024] The transverse large cylinder is provided with a fine thread area on the right side, and a pair of through-thread holes are arranged on the fine thread area;

[0025] The transverse large cylinder is provided with a meshed reinforcing rib on the outside, and the through-thread holes are arranged on the meshed reinforcing rib;

[0026] The transverse small cylinder is provided with a round square opening in the middle, a fine thread on the left end of the transverse small cylinder, and a plurality of reinforcing ribs on the outside.

[0027] Further, the longitudinal cylinder is provided with three kinds of diameter openings in the inside, from the left side to the right side of the inside of the longitudinal cylinder, they are a bearing axial limiting hole with the smallest diameter, a first bearing matching hole, a transition hole with the largest diameter and a second bearing matching hole, the first bearing matching hole and the second bearing matching hole are matched with the ball bearing;

[0028] The longitudinal cylinder is provided with a first six-hole connecting flange on the outside of the right side, which corresponds to a second six-hole connecting flange on the outside of the gear ring, and the two are fixedly connected through bolts and nuts.

[0029] Further, the vertical cylinder is provided with an internal thread hole on the outside, and a round square opening in the inside, the internal thread hole is matched with a compression adjusting nut to adjust the compression force, and the round square opening is matched with the side surface of the rack compression block to realize the horizontal and vertical limiting of the rack compression block.

[0030] Further, the middle part of the four-corner connecting ring is larger in diameter than the opening diameter of the two sides, and a housing rubber support and a housing metal support are embedded thereon, the housing metal support is connected with a suspension mechanism supporting the front wheels and the rear wheels of the automobile through bolts.

[0031] Further, the guide spring pad in the self-return device includes a first guide spring pad and a second guide spring pad, the left side plane of the first guide spring pad is matched with the right side plane of the rack and the right side step plane of the diverter housing, and the right side plane of the second guide spring seat is matched with the left side plane of the rack adjusting nut and the left side plane of the housing adjusting nut;

[0032] The inner ring surface diameter of the first guide spring pad is larger than the diameter of the rack, and chamfers are arranged on both sides to prevent jamming;

[0033] The diameter of the convex ring surface of the first guide spring pad is smaller than the diameter of the inner ring surface of the return spring, so as to ensure that the two are slightly combined with each other;

[0034] The convex flat surface of the first guide spring pad is in close contact with the flat ring surface of the return spring.

[0035] Further, the first guide spring pad and the second guide spring pad are mixed material components, the main body of which is composed of Teflon, brass or other low friction coefficient plastic, the bottom of which is composed of rubber or other elastic material, and the main body and the bottom are tightly bonded, and a corresponding socket is arranged on the main body to realize the close connection of the main body and the bottom.

[0036] Further, the maximum diameter of the rack, the maximum diameter of the guide spring pad and the maximum diameter of the return spring are all smaller than the internal diameter of the large transverse cylinder of the steering gear housing, the maximum diameter of the rack adjusting nut is smaller than the minimum diameter of the housing adjusting nut, the rack adjusting nut is provided with a hexagonal assembly feature, the minimum diameter of the housing adjusting nut is provided with a semicircular assembly feature, the locking screw is provided with a tapered top feature and an internal hexagonal assembly feature, and is locked in a deformed manner.

[0037] Compared with the prior art, the present application has the following advantages:

[0038] (1) The structure is simple, the parts are compact, the response speed is high, and the service life is long; compared with the traditional steering gear and the modern steer-by-wire steering gear, the mass is small, the transverse and vertical space occupation is small; compared with other self-return steering gears, the self-return angle can reach 30°, and the self-return force in the small angle range of 3-5° is also considerable, which can realize complete self-return; it can be compatible with any form of mechanical steering and steer-by-wire transmission device, and can replace the reducer and motor customized according to the product, has strong product force and mutual compatibility, and is suitable for large-scale production; and realizes self-return of mechanical movement under the failure of electric control, greatly guarantees the driving safety of the automobile, and is a highlight of automobile passive safety design.

[0039] (2) The special design of the rack and the interaction with the return spring, the spring guide seat and the adjusting nut make the rack return to zero position only through mechanical movement after displacement, that is, drive the steering wheel to return to zero position, realize the self-return function of steering, and when applied to rear wheel steering, the self-return operation of the rear wheel in a 30° steering angle to zero position can be realized. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 It is a complete assembly drawing of the preferred embodiment of the present application.

[0041] Figure 2 It is an assembly drawing of the preferred embodiment of the present application without the steering gear housing and its attached and whole vehicle connecting components.

[0042] Figure 3 A lateral vertical cross-sectional view of a preferred embodiment of the present invention.

[0043] Figure 4 A lateral vertical cross-sectional view of a preferred embodiment of the present invention.

[0044] Figure 5 A vertical cross-sectional view along the centerline of the steering motor of a preferred embodiment of the present invention.

[0045] Figure 6 A partial enlarged view of the self-aligning mechanism of a lateral vertical cross-sectional view and an upper cross-sectional view of a preferred embodiment of the present invention.

[0046] Figure 7 A partial enlarged view of the rack and pinion of a lateral vertical cross-sectional view of a preferred embodiment of the present invention.

[0047] Figure 8 A vertical cross-sectional view along the centerline of the steering motor with detailed feature labels of a preferred embodiment of the present invention.

[0048] Figure 9 A partial enlarged view of the housing end of a lateral vertical cross-sectional view of a preferred embodiment of the present invention.

[0049] Figure 10 A plurality of directional cross-sectional views of a housing of a preferred embodiment of the present invention.

[0050] Figure 11 A plurality of directional views of a housing of a preferred embodiment of the present invention.

[0051] Figure 12 A perspective view of a housing and housing supported parts of a preferred embodiment of the present invention.

[0052] Figure 13 A schematic view of the structure of a part of a preferred embodiment of the present invention.

[0053] Figure 14 A schematic view of the structure of a part of a preferred embodiment of the present invention.

[0054] Figure 15 A schematic view of the structure of a part of a preferred embodiment of the present invention.

[0055] Figure 16 A schematic view of the structure of a part of a preferred embodiment of the present invention.

[0056] Figure 17 A schematic view of the structure of a part of a preferred embodiment of the present invention.

[0057] Figure 18 A simplified model diagram of the self-aligning principle of a car self-aligning steering device of the present invention.

[0058] Figure 19 Figure 1 is a physical simplified model diagram of the rear wheel steering automatic self-aligning system of the automobile self-aligning steering gear of the present application.

[0059] Figure 20 Figure 2 is a required aligning force and aligning force versus displacement graph of the preferred embodiment of the automobile of the present application.

[0060] In the figure: 1 - diverter housing; 2 - rack; 3 - first guide spring pad; 4 - return spring; 5 - second guide spring pad; 6 - rack adjusting nut; 7 - first locking screw, 8 - second locking screw, 10 - third locking screw, 11 - fourth locking screw; 9 - housing adjusting nut; 12 - first housing rubber support, 14 - second housing rubber support, 30 - third housing rubber support, 32 - fourth housing rubber support; 13 - first housing metal support, 15 - second housing metal support, 31 - third housing metal support, 33 - fourth housing metal support; 16 first sealing ring, 34 - second sealing ring; 17 - first bearing bush end cover, 35 - second bearing bush end cover; 18 - first wave-shaped sealing rubber, 36 - second wave-shaped sealing rubber; 19 - first rod end bearing, 25 - second rod end bearing, 37 - third rod end bearing, 43 - fourth rod end bearing; 20 - first rod end bearing adjusting nut, 26 - second rod end bearing adjusting nut, 38 - third rod end bearing adjusting nut, 44 - fourth rod end bearing adjusting nut; 21 - first plug, 39 - second plug; 22 - first nut, 40 - second nut; 23 first U-shaped joint, 41 - second U-shaped joint; 24 - first steering tie rod, 42 - second steering tie rod; 27 - compression adjusting nut; 28 - compression spring; 29 - rack compression block; 45 - first ball bearing; 47 - second ball bearing; 49 - first needle bearing; 51 - second needle bearing; 53 - third needle bearing; 55 - fourth needle bearing; 57 - fifth needle bearing; 59 - sixth needle bearing; 61 - seventh needle bearing; 63 - eighth needle bearing; 46 - steering gear; 48 - second carrier; 50 - first planet gear, 52 - second planet gear, 54 - third planet gear, 58 - fourth planet gear, 60 - fifth planet gear, 62 - sixth planet gear; 56 - first carrier; 64 - sun gear; 65 - ring gear; 66 - steering motor; 67 - first bolt, 68 - second bolt, 69 - third bolt, 70 - fourth bolt, 71 - fifth bolt, 72 - sixth bolt; 73 - third nut, 74 - fourth nut, 75 - fifth nut, 76 - sixth nut, 77 - seventh nut, 78 - eighth nut;1a - step, 1b - inner wall, 1c - fine internal thread area, 1d - mesh reinforcement, 1e - through hole, 1f - four-corner connecting ring, 1j - internal thread hole, 1k - round square opening, 1m - bearing axial limiting hole, 1n - first bearing matching surface, 1p - second bearing matching surface, 1o - transition hole, 1r - first six-hole connecting flange, 2a - shoulder, 2b - external thread area, 2c - step, 2d - first smooth friction area, 2e - internal thread hole, 2f - toothed area, 2g - V-shaped groove, 2h - limiting step, 2i - second smooth friction area, 2j - internal thread hole, 3a - first plane, 3b - inner annular surface, 3c - second main body, 3d - convex annular surface, 4a - circular annular surface, 4b - inner annular surface diameter, 5a - second plane, 6a - third plane, 6c - hexagonal assembly feature, 7b - taper top feature, 7c - inner hexagonal assembly feature, 9a - semicircular assembly feature, 9c - fourth plane, 27a - feature annular groove, 27b - feature inner hexagon, 29a - V-shaped groove, 29b - feature groove, 29c - feature groove, 45a - first bearing outer ring matching surface, 45b - first bearing inner ring matching surface, 46a - feature tooth shape, 46b - feature middle through hole, 46c - shoulder, 46d - feature bearing matching surface, 46e - feature chamfer, 46f - feature internal spline, 46g - first chamfer, 47a - second bearing outer ring matching surface, 47b - second bearing inner ring matching surface, 48a - second chamfer, 48c - cylindrical support, 48d - step, 48e - round hole, 56a - central support cylinder, 56b - step, 56c - sun gear tooth shape, 56e - step, 56g - round hole, 56f - cylindrical support, 64a - cylindrical support, 64b - step, 64c - toothed part, 64d - spline groove, 65a - feature gear ring, 65b - second six-hole connecting flange, 65c - limiting end face, 65d - counterbore, 65e - groove, a - thread feature, b - hole ball hinge feature, c - wrench clamping surface feature, d - rod part, e - wrench clamping surface feature, f - thread feature, g - thread feature, h - hole ball hinge feature, i - round hole, j - U-shaped feature, k - rubber clamping groove, l - thread feature. DETAILED DESCRIPTION

[0061] The application will be described in detail below with reference to the drawings and specific embodiments.

[0062] EMBODIMENT

[0063] As shown in Figure 1 and Figure 2 , a compact self-aligning steering gear of a steer-by-wire steering system for a vehicle is mounted on a vehicle chassis, which comprises a reducer device, a steering motor 66, a rack and pinion transmission device, a steering gear support and wrapping device, a self-aligning device, and two side tie rods and their connecting devices.

[0064] As Figure 5 shown, the reducer device is internally provided with a double-stage planetary gear reducer device, including a sun gear 64, planetary gears, a ring gear 65, a first planetary carrier 56, a second planetary carrier 48, and a needle bearing device, wherein the planetary gears include a first planetary gear 50, a second planetary gear 52, a third planetary gear 54, a fourth planetary gear 58, a fifth planetary gear 60, a sixth planetary gear 62, and the needle bearings include a first needle bearing 49, a second needle bearing 51, a third needle bearing 53, a fourth needle bearing 55, a fifth needle bearing 57, a sixth needle bearing 59, a seventh needle bearing 61, and an eighth needle bearing 63. The sun gear 64 is connected with the output shaft of the steering motor 66 and is engaged with the fourth planetary gear 58, the fifth planetary gear 60, and the sixth planetary gear 62, which are engaged with the ring gear 65. The fourth planetary gear 58, the fifth planetary gear 60, and the sixth planetary gear 62 are respectively matched with the three columnar protrusions of the first planetary carrier 56 through the sixth needle bearing 59, the seventh needle bearing 61, and the eighth needle bearing 63. The first planetary carrier 56 is matched with the second planetary carrier 48 through the first needle bearing 49. The sun gear part of the first planetary carrier 56 is engaged with the first planetary gear 50, the second planetary gear 52, and the third planetary gear 54, which are matched with the second planetary carrier 48 through the second needle bearing 51, the third needle bearing 53, and the fourth needle bearing 55. The outer spline of the second planetary carrier 48 is matched with the inner spline of the steering gear 46.

[0065] As Figure 5As shown, the assembly sequence of the whole reducer should be: first, assemble the steering motor 66 to the reducer housing 65, and fasten it with the anti-loosening bolt. Second, place the four needle bearings 57, 59, 61, 63 on the feature cylinder 56f and the round hole 56g of the first planet carrier, then insert the feature cylinder 64a of the sun gear 64 into the round hole 56g of the planet carrier, and place the planet gears 58, 60, 62 on the feature cylinder 56f. Third, place the first needle bearing 49, the second needle bearing 51, the third needle bearing 53 and the fourth needle bearing 55 on the feature cylinder 48c and the round hole 48e of the second planet carrier, and place the first planet gear 50, the second planet gear 52 and the third planet gear 54 on the feature cylinder 48c, and insert the feature hole 48e of the assembly into the feature cylinder 56a obtained in the previous step. Fourth, insert the whole assembly into the reducer housing 65, and rotate the two planet carriers appropriately to ensure that the six planet gears mesh with the feature 65a of the reducer housing 65. If it cannot be inserted to the bottom, rotate the second planet carrier 48 so that the feature spline 64d of the sun gear 64 is in phase with the feature spline of the steering motor, and then insert it to the bottom. Fifth, insert the whole reducer assembly into the steering gear that has been assembled, align the feature spline 48a of the reducer assembly with the feature spline 46f of the steering gear, rotate the reducer assembly so that the feature flange hole 65b is aligned with the feature flange hole Ir of the steering gear housing, and fasten it with the bolt and nut.

[0066] The steering motor 66 is located outside the reducer device and connected to it, and its attached communication cable is connected to the vehicle electronic control unit. It is connected to the reducer device through the cooperation of the first bolt 67, the second bolt 68, the third bolt 69, the fourth bolt 70, the fifth bolt 71, the sixth bolt 72, the third nut 73, the fourth nut 74, the fifth nut 75, the sixth nut 76, the seventh nut 77 and the eighth nut, and its attached communication cable is connected to the vehicle ECU, where ECU stands for automobile electronic control unit.

[0067] As shown, Figure 7 The gear rack transmission device is arranged in the steering gear housing 1, including a steering gear 46, a first ball bearing 45, a second ball bearing 47, a rack 2 and a rack compression mechanism. The gear rack transmission device converts the rotational motion of the steering gear 46 into the linear motion of the rack 2. The rack compression mechanism includes a rack compression block 29, a compression spring 28 and a compression adjusting nut 27. By adjusting the compression adjusting nut 27 assembled on the steering gear housing 1, the rack compression mechanism pushes the compression spring 28 to make the rack compression block 29 generate a set of axial force, ensuring the normal operation of the gear rack transmission device and offsetting the deformation caused by the internal force.

[0068] like Figure 9 As shown, the steering gear support and wrapping device is installed on both sides of the steering gear housing 1 and includes a first sealing ring 16, a second sealing ring 34, a first bearing end cap 17, a second bearing end cap 35, a first wave sealing rubber 18, and a second wave sealing rubber 36. Round holes are provided in the middle of the first bearing end cap 17 and the second bearing end cap 35 to support, center, and lubricate the linearly moving rack 2. The wave sealing rubber wraps the rack 2, rod end bearing, U-joint, and corresponding fasteners that are exposed from the steering gear housing 1, ensuring the overall sealing and dustproofing of the steering gear.

[0069] like Figure 6 As shown, the self-centering device includes a steering gear housing 1, a rack 2, a first guide spring pad 3, a second guide spring pad 5, a return spring 4, a rack adjusting nut 6, a housing adjusting nut 9, a first locking screw 7, a second locking screw 8, a third locking screw 10 and a fourth locking screw 11. The steering gear housing 1 is connected to a suspension mechanism supporting the front or rear wheels of the vehicle. The guide spring pads are arranged on both sides of the return spring 4. The guide spring pads and the return spring 4 are sleeved on the right end of the rack 2. The compression amount of the return spring 4 is adjusted by the rack adjusting nut 6 and locked by the locking screw. The above components are placed in the right cylinder of the steering gear housing 1 and limited by the housing adjusting nut 9, so that the left side of the first guide spring pad 3 simultaneously contacts the left step 1a of the right cylinder of the steering gear housing 1 and the left side of the right end shoulder 2a of the rack 2, so that the right side of the second guide spring pad 5 simultaneously contacts the left side of the rack adjusting nut 6 and the left side of the housing adjusting nut 9. At this time, use the third locking screw 10 and the fourth locking screw 11 to lock.

[0070] like Figure 7 As shown, the tie rods on both sides and their connecting devices include multiple rod end bearings, multiple U-shaped joints, and multiple steering tie rods. The rod end bearings include a first rod end bearing 19, a second rod end bearing 25, a third rod end bearing 37, and a fourth rod end bearing 43. The U-shaped joints include a first U-shaped joint 23 and a second U-shaped joint 41. The steering tie rods include a first steering tie rod 24 and a second steering tie rod 42. The first steering tie rod 24 and the second steering tie rod 42 are connected to the first rod end bearing 19 and the third rod end bearing 37, respectively, and can rotate around the ball bearing centerline of the rod segment bearing within a large angle range or tilt horizontally within a small angle range. They are connected to the steering point on the wheel side column through the second rod end bearing 25 and the fourth rod end bearing 43 disposed outside the first steering tie rod 24 and the second steering tie rod 42.

[0071] The maximum diameter of the rack 2, the maximum diameter of the guide spring pad, the maximum diameter of the return spring 4 are all smaller than the internal diameter of the transverse large cylinder of the steering gear housing 1, the maximum diameter of the rack adjusting nut 6 is smaller than the minimum diameter of the housing adjusting nut 9, the rack adjusting nut 6 is provided with a hexagonal assembly feature 6c, and a hexagonal tool is used for assembly; the minimum diameter of the housing adjusting nut 9 is provided with a semicircular assembly feature 9a, and a special tool is used for assembly; the locking screw is provided with a tapered top feature 7b, which is locked in a deformed manner, and the locking screw is provided with an internal hexagonal assembly feature 7c, and a hexagonal tool is used for assembly.

[0072] As shown in Figure 13 The right side of the rack 2 is provided with a feature shoulder 2a, an external thread area 2b, a first limiting step 2c, a first smooth friction area 2d, and a first internal threaded hole 2e; the right side of the rack 2 is provided with a tooth-shaped area 2f, a V-shaped groove 2g, a second limiting step 2h, a second smooth friction area 2i, and a second internal threaded hole 2j.

[0073] Among the above features, the V-shaped groove 2g is formed by milling twice with an angle of 90°, which cooperates with the V-shaped groove 29a of the pressing mechanism to jointly limit the circumferential rotation of the rack. The diameter of the shoulder 2a is larger than that of the rest of the parts, the external thread area 2b is a fine thread, which ensures self-locking under oil lubrication conditions, and the thread area from the right end to the left is slightly larger than the area engaged with the rack adjusting nut 6. The step 2c is the starting position of the external thread area 2b, which is also a transverse limiting feature of the steering gear. The first smooth friction area 2d and the second smooth friction area 2i are respectively inserted into the circular holes in the centers of the first bearing bush end cover 17 and the second bearing bush end cover 35 on both sides of the housing. The internal threaded holes 2e and 2j are respectively connected through the first rod end bearing 19 and the third rod end bearing 37, the first U-shaped joint 23 and the second U-shaped joint 41, and the first and second steering tie rods 24 and 42. The connection lengths of the left and right sides of the rack 2 can be adjusted by the first and third rod end bearing adjusting nuts 20 and 38. The lengths of the first and second steering tie rods 24 and 42 can be adjusted by adjusting the second and fourth rod end bearing adjusting nuts 26 and 44.

[0074] As shown in Figure 17 The steering tie rods 24 and 42 at the left and right ends are completely identical and have thread features a and f, wrench clamping surface features c and e, and a middle rod part d. The U-shaped joint has U-shaped features j, circular holes i, rubber clamping grooves k, and thread features 1. The rod end bearing has thread features g and hole ball hinge features h.

[0075] The assembly sequence of the parts of the self-centering mechanism is as follows: first, lubricate the outer surface of the rack 2, and sequentially pass through the guide spring pad 3, the centering spring 4, and the guide spring pad 5; second, use the rack adjusting nut 6 to pre-tighten into the threaded area 2b of the rack 2 to compress the centering spring 4, and the compression amount is determined by a calculation formula; the pre-tightening speed is fast, and when the designed position is reached, the tightening speed is slowed down, and a distance measuring tool is used to measure the length of the centering spring 4, so that the length of the spring finally reaches the designed length; after the rack adjusting nut 6 is in place, the locking screws 7 and 8 are used to lock the rack adjusting nut 6; third, insert the above assembly from the large cylinder direction into the steering gear housing 1, and note that the inner surface of the housing is lubricated in advance to prevent scratching; fourth, use the housing adjusting nut 9 to pre-tighten into the threaded area 1c of the steering gear housing 1, and the depth is determined by the assembly design; when the right surface of the housing adjusting nut 9 is about to be combined with the right surface of the rack adjusting nut 6, the tightening speed is slowed down, and a torque measuring tool is used to measure the torque of the housing adjusting nut 9; when the torque is slightly greater than the designed torque, the nut is tightened in the opposite direction until the torque reaches the designed torque. This ensures that the left plane 6a of the rack adjusting nut 6 is combined with the left plane 9c of the housing adjusting nut 9; fifth, test whether the self-centering device is working correctly, otherwise repeat step four, and if so, use the locking screws 9 and 10 to lock the housing adjusting nut 9. The calculation formula for the above depth is s=F / k, where s is the pre-compression amount, F is the zero-centering force, and k is the spring stiffness coefficient.

[0076] As shown in Figure 10 and Figure 11 The steering gear housing 1 body is composed of a horizontal large cylinder, a horizontal small cylinder, a longitudinal cylinder, a vertical cylinder, and a four-corner connecting ring 1f. In this embodiment, the number of longitudinal cylinders and vertical cylinders is one. The left side of the horizontal large cylinder is provided with a step 1a, and the right side of the step 1a is a smooth inner wall 1b; the right side of the horizontal large cylinder is provided with a fine internal thread area 1c, and a pair of through-thread holes 1e are arranged on the internal thread area 1c; the outside of the horizontal large cylinder is provided with a meshed reinforcing rib 1d, and the through-thread holes 1e are arranged on the meshed reinforcing rib 1d; the middle of the horizontal small cylinder is provided with a round-cornered square opening 1k, the left end of the horizontal small cylinder is provided with a fine thread, and the outside is provided with a plurality of reinforcing ribs 1s.

[0077] As shown in Figure 8 and Figure 10 The inside of the longitudinal cylinder is provided with three kinds of diameter openings, which are sequentially arranged from the left side to the right side of the inside of the longitudinal cylinder, i.e., the bearing axial limiting hole 1m with the smallest diameter, the first bearing matching hole 1n, the largest diameter transition hole 1o, and the second bearing matching hole 1p, which are matched with the first ball bearing 45 and the second ball bearing 47.

[0078] The right side of the longitudinal cylinder is externally provided with a first six-hole connecting flange 1r, which corresponds to the second six-hole connecting flange 65b outside the gear ring 65, and the two are fixedly connected through bolts and nuts.

[0079] The feature shoulder 1m of the steering gear housing 1 serves as the axial limit of the bearing 45, the first feature bearing fitting surface 1n and the second feature bearing fitting surface 1p are in interference fit with the first bearing outer ring fitting surface 45a and the second bearing outer ring fitting surface 47a, and the bearing fitting transition surface 1o is further provided on the steering gear housing 1, which has a diameter slightly larger than the bearing fitting surface, and is used to ensure easy assembly of the bearing and reduce the cost of high-precision boring of the entire barrel-shaped inner surface. The installation steps of this part should be: first, assemble the first ball bearing 45 into the first feature bearing fitting surface 1n, then assemble the rack into the steering gear housing 1 from the large-diameter port, and then fix the rack, and then press the steering gear 46 and the second ball bearing 47 into the housing second feature bearing fitting surface 1p at the same time.

[0080] The vertical cylinder is externally provided with an internal thread hole 1j, and the vertical cylinder is internally provided with a rounded square opening 1k. The internal thread hole 1j cooperates with the compression adjusting nut 27 to adjust the compression force. The compression nut 27 has a feature annular groove 27a to ensure the positioning of the compression spring 28, and has a feature internal hex 27b to ensure the adjustment of the compression force. The rounded square opening 1k cooperates with the side surface of the rack compression block 29 to realize the transverse and longitudinal limiting of the rack compression block 29. The rack compression block 29 is provided with a feature annular groove 29c to ensure the positioning of the compression spring 28, and a feature groove 29b is provided in advance to ensure the machining of the feature V-shaped groove 29a.

[0081] As shown in Figure 12 The middle part of the four-corner connecting ring 1f has a larger diameter than the two side openings, and is embedded with a housing rubber support and a housing metal support. The housing rubber support includes a first housing rubber support 12, a second housing rubber support 14, a third housing rubber support 30, and a fourth housing rubber support 32. The housing metal support includes a first housing metal support 13, a second housing metal support 15, a third housing metal support 31, and a fourth housing metal support 33. The housing metal support is connected to the suspension mechanism supporting the front and rear wheels of the automobile through bolts.

[0082] As shown in Figure 6As shown, the guide spring pad in the self-centering device includes a first guide spring pad 3 and a second guide spring pad 5. The left side plane 3a of the first guide spring pad 3 is in line with the right side plane 2a of the rack 2 and the right side stepped plane la of the steering gear housing 1. The right side plane 5a of the second guide spring pad 5 is in line with the left side plane 6a of the rack adjusting nut 6 and the left side plane 9c of the housing adjusting nut 9. The self-centering spring is a pre-compressed spring. The pre-compression amount is determined by the thread engagement depth of the rack adjusting nut 6. The two in-line engagement depends on the thread engagement depth of the rack adjusting nut 6 and the thread engagement depth of the housing adjusting nut 9, and the thicknesses of the two are the same. The inner ring surface 3b of the guide spring pad 3 is slightly larger in diameter than the diameter of the rack 2, and the two sides are chamfered to prevent jamming. The outer convex ring surface 3d of the guide spring pad 3 is slightly smaller in diameter than the inner ring surface diameter 4b of the self-centering spring 4, to ensure that the two are slightly combined with each other. The convex plane 3c of the guide spring pad 3 is in close contact with the flat ring surface 4a of the self-centering spring 4. The guide spring pad 5 is a mirror image assembly, which is identical to the guide spring pad 3 in shape, function, material, process, and assembly.

[0083] As shown in Figure 8 and Figure 15 The steering gear 46 has a feature inner spline 46f, which can be interchangeably assembled with various forms of motor reducer forms. In this embodiment, the outer spline of the second planet carrier 48 in the steering gear reducer structure is in line with the inner spline of the steering gear 46, with the same tooth shape, modulus, and tooth number, and the two are matched with each other. At the same time, the end of the spline is provided with a first chamfer 46g and a second chamfer 48a to ensure smooth assembly. The depth of the inner spline 46f is slightly larger than the spline thickness of 48a to eliminate the influence of assembly errors and ensure a certain floating range of the second planet carrier 48. The steering gear 46 is provided with a shoulder 46c, which limits the axial movement of the ball bearing. The feature bearing matching surface 46d of the steering gear 46 is matched with the first bearing inner ring matching surface 45b and the second bearing outer ring matching surface 47b in an interference fit. At the same time, the feature chamfer 46e of the steering gear 46 can effectively ensure the assembly with the bearing.

[0084] Figure 7 As shown, the steering gear 46 has a feature tooth shape 46a, which is in mesh with the tooth shape part 2f of the rack 2, converting the rotary motion of the gear 46 into the linear motion of the rack 2. The steering gear 46 also has a feature middle through hole 46b to facilitate machining and clamping and to reduce the weight of the gear.

[0085] As shown in Figure 15As shown, the first planet carrier 56 and the second planet carrier 48 share common planet carrier features, including raised steps 56e and 48d, raised, evenly spaced cylindrical supports 56f and 48c, and chamfered central holes 56g and 48e. The raised steps 56e and 48d are used to relieve stress at vertical corners. The first planet carrier 56 also features a characteristic sun gear tooth profile 56c, a central support cylinder 56a, and a step 56b. The second planet carrier 48 also has a spline 48a for connection to the steering gear 46. The sun gear 64 similarly features a cylindrical support 64a, a step 64b, a tooth profile 64c, and a spline groove 64d. All planet gears share identical parameters, including module and number of teeth, and all feature chamfers for ease of assembly.

[0086] like Figure 16 As shown, the reducer housing 65 has a characteristic gear ring 65a and a flange circular hole 65b for connecting to the steering gear housing. The reducer housing 65 is also provided with a reducer axial limiting end face 65c, six countersunk holes 65d for connecting to the motor, and a weight-reducing groove 65e.

[0087] The self-centering principle of this self-centering steering gear is as follows:

[0088] Figure 18 This schematic diagram shows an embodiment of the linear displacement self-homing mechanism. It includes the following main components: housing 1, rack 2, spring 4, guide spring washer 3, housing adjustment nut 6, and rack adjustment nut 9. The spring is pre-compressed, meaning it remains compressed when the mechanism is in its zero position. The mechanism has three states: zero position, relative left displacement, and relative right displacement.

[0089] When the rack is in zero position, its left guide spring pad is in contact with the housing adjustment nut and the rack adjustment nut at the same time, and the right guide spring pad is in contact with the step feature on the right side of the housing and the rack shoulder feature at the same time. At this time, the elastic forces on both sides of the spring are transmitted to the housing and the rack at the same time, with equal magnitude and opposite direction, and the rack remains stationary.

[0090] When the rack moves to the left, it pushes the right guide spring pad to the left and leaves the right step surface of the housing, and the left rack nut leaves the left guide spring pad. The left guide spring pad only contacts the housing nut and remains stationary, thus generating spring compression. The left spring pad acts as a support, and the spring gives the right guide spring pad an elastic force to the right, thereby pushing the rack back to zero position.

[0091] When the rack is displaced to the right, it pushes the left guide spring washer away from the housing nut, and the rack shoulder surface leaves the right guide spring washer, which is only in contact with the right step surface of the housing and is stationary, thus generating spring compression. The right spring washer acts as a support, and the spring exerts an elastic force on the left guide spring washer to the left, thereby pushing the rack back to the zero position.

[0092] Figure 19 A physical model of the linear self-homing mechanism is built, which can more clearly show the relationship between the various parts and supplement the self-homing principle. m3 represents the metal part of the spring washer, m4 represents the outer rubber part of the spring washer, m5 represents the inner rubber part of the spring washer, m6 represents the rack, l1 represents the housing limiting distance, l2 represents the compressed main spring length, l3 represents the metal part thickness of the spring washer, l4 represents the outer rubber part thickness of the spring washer, l5 represents the inner rubber part thickness of the spring washer, and l6 represents the rack limiting distance. The rubber contact between m3 and m4 is replaced by a spring with damping, the spring between left m3 and right m3 is replaced by a spring with damping, m4 is in direct contact with the fixed surface, and m5 is in direct contact with m6.

[0093] Figure 20 The specific return force effect of an embodiment of the linear self-homing mechanism and the relationship between the required return force effect and the relative displacement are shown. The rack return force is symmetrical to the left and right, and the combined line is composed of two straight lines starting from zero and a smooth connecting curve in the middle. The required rack return force is symmetrical to the left and right, and the curve gradually slows down in slope from the non-zero outward extension. As can be seen from the figure, in most of the bilateral symmetrical interval (∞, -a) ∪ (a, ∞), the return force generated by the mechanism is greater than the required return force, which can achieve the self-return effect, that is, the self-homing effect of the rack; in the middle small interval (-a, a), the return force generated by the mechanism is less than the required return force, and cannot produce the return effect. The size of a is related to the rubber side stiffness of the guide spring washer, and the rubber side stiffness of the guide spring washer is directly related to the processing and assembly precision, the self-homing response characteristics of the mechanism, and the specific size needs to be designed comprehensively considering the three factors.

Claims

1. A compact self-aligning steering gear for steer-by-wire automotive vehicles, characterized in that, The self-correcting steering gear is mounted on the chassis of a car, comprising a reducer device, a steering motor (66), a rack and pinion transmission device, a steering gear support and wrapping device, a self-correcting device and two lateral tie rods and their connecting devices; The reducer device is internally provided with a double-stage planetary gear reducer device; The steering motor (66) is located outside the reducer device and connected with the reducer device, and the communication cable attached thereto is electrically connected with the electronic control unit of the car; The rack and pinion transmission device is arranged in the steering gear housing (1) and comprises a steering gear (46), a ball bearing, a rack (2) and a rack pressing mechanism, the rack and pinion transmission device converts the rotary motion of the steering gear (46) into the linear motion of the rack (2), and the rack pressing mechanism comprises a rack pressing block (29), a pressing spring (28) and a pressing adjusting nut (27), the rack pressing mechanism pushes the pressing spring (28) by adjusting the pressing adjusting nut (27) assembled on the steering gear housing (1), so that the rack pressing block (29) generates a set axial force, thereby ensuring the normal operation of the rack and pinion transmission device and offsetting the deformation caused by the internal force of the rack and pinion transmission device; The steering gear support and wrapping device is arranged on both sides of the steering gear housing (1) and comprises a sealing ring, a bearing bush end cover and a wave sealing rubber; The self-correcting device comprises a steering gear housing (1), a rack (2), a guide spring pad, a correcting spring (4), a rack adjusting nut (6), a housing adjusting nut (9) and a locking screw, the steering gear housing (1) is connected with the suspension mechanism supporting the front wheel or the rear wheel of the vehicle, the guide spring pad is arranged on both sides of the correcting spring (4), the guide spring pad and the correcting spring (4) are sleeved on the right end of the rack (2), the compression amount of the correcting spring (4) is adjusted by the rack adjusting nut (6), and the locking screw is locked; The two lateral tie rods and their connecting devices comprise a plurality of rod end bearings and a plurality of steering tie rods, the steering tie rods are connected with the rod segment bearings and make rotary motion or inclined motion around the spherical bearing center line of the rod segment bearings, and the rod end bearings arranged on the outer side of the steering tie rods are used to connect the steering points on the wheel-side vertical columns; The right side of the rack (2) is provided with a characteristic shoulder (2a), an external thread area (2b), a first limiting step (2c), a first smooth friction area (2d) and a first internal thread hole (2e); the right side of the rack (2) is provided with a tooth-shaped area (2f), a V-shaped groove (2g), a second limiting step (2h), a second smooth friction area (2i) and a second internal thread hole (2j); The diameter of the shoulder (2a) is greater than that of the rest of the rack (2), the external thread area (2b) is a fine thread, which is used to ensure self-locking under oil lubrication, and the first limiting step (2c) is the starting position of the external thread area (2b) and limits the lateral position of the steering gear. The first smooth friction area (2d) and the second smooth friction area (2i) are respectively inserted into the circular holes in the center of the first bearing bush end cover (17) and the second bearing bush end cover (35) on both sides of the steering gear housing (1); The rod end bearing and the U-shaped joint are connected with the steering tie rods on both sides through the first inner threaded hole (2e) and the second inner threaded hole (2j); The guide spring pad in the self-centering device includes a first guide spring pad (3) and a second guide spring pad (5), the left side plane (3a) of the first guide spring pad (3) is fitted with the right side plane of the feature shoulder (2a) of the rack (2) and the right side step plane of the steering gear housing (1); the right side plane (5a) of the second guide spring pad (5) is fitted with the left side plane (6a) of the rack adjusting nut (6) and the left side plane (9c) of the housing adjusting nut (9); The inner annular surface (3b) of the first guide spring pad (3) has a diameter larger than the diameter of the rack (2), and both sides are provided with chamfers to prevent jamming; The outer convex annular surface (3d) of the first guide spring pad (3) has a diameter smaller than the inner annular surface diameter (4b) of the self-centering spring (4), so as to ensure that the two are slightly combined with each other; The convex plane (3c) of the first guide spring pad (3) is in close contact with the flat annular surface (4a) of the self-centering spring (4).

2. A compact self-aligning steering gear for steer-by-wire steering of a vehicle according to claim 1, characterized in that The main body of the steering gear housing (1) is composed of a transverse large cylinder, a transverse small cylinder, a longitudinal cylinder, a vertical cylinder and a four-corner connecting ring (1f).

3. A compact self-aligning steering gear for steer-by-wire steering of a vehicle according to claim 2, characterized in that The left side of the transverse large cylinder is provided with a step (1a), and the right side of the step (1a) is a smooth inner wall (1b); The right side of the transverse large cylinder is provided with a fine thread inner threaded area (1c), and the inner threaded area (1c) is provided with a pair of through threaded holes (1e); The transverse large cylinder is provided with a meshed reinforcing rib (1d) on the outside, and the through threaded holes (1e) are arranged on the meshed reinforcing rib (1d); The transverse small cylinder is provided with a round square opening in the middle, a fine thread at the left end of the transverse small cylinder, and a plurality of reinforcing ribs (1s) on the outside.

4. A compact self-aligning steering gear for steer-by-wire steering of a vehicle according to claim 2, characterized in that The longitudinal cylinder is provided with three kinds of diameter openings inside, from the left side to the right side of the longitudinal cylinder inside, in sequence, the smallest diameter bearing axial limiting hole (1m), the first bearing matching hole (1n), the largest diameter transition hole (1o) and the second bearing matching hole (1p), the first bearing matching hole (1n) and the second bearing matching hole (1p) are matched with the ball bearing; The right side of the longitudinal cylinder is provided with a first six-hole connecting flange (1r) on the outside, which corresponds to the second six-hole connecting flange (65b) on the outside of the gear ring (65), and the two are fixedly connected through bolts and nuts.

5. A compact self-aligning steering gear for steer-by-wire steering of an automobile according to claim 2, characterized by The vertical cylinder is provided with an inner threaded hole (1j) on the outside, and a round square opening in the inside, the inner threaded hole (1j) is matched with the pressing adjusting nut (27) to adjust the pressing force, and the round square opening is matched with the side surface of the rack pressing block (29) to realize the horizontal and vertical limiting of the rack pressing block (29).

6. A compact self-aligning steering gear for steer-by-wire steering of an automobile according to claim 2, characterized by The middle diameter of the four-corner connecting ring (1f) is greater than the two-side opening diameter, and the housing rubber support and the housing metal support are embedded on the four-corner connecting ring (1f), and the housing metal support is connected with the suspension mechanism supporting the front and rear wheels of the automobile through bolts.

7. A compact self-aligning steering gear for steer-by-wire steering of an automotive vehicle according to claim 1, wherein The first guide spring pad (3) and the second guide spring pad (5) are mixed material components, the main body of which is composed of Teflon, brass or other low friction coefficient plastic, and the bottom of which is composed of rubber or other elastic material, and the two are tightly bonded, wherein the main body is provided with a corresponding socket to realize the tight connection of the main body and the bottom.

8. A compact self-aligning steering gear for steer-by-wire steering of an automobile according to claim 1, characterized by The maximum diameter of the rack (2), the maximum diameter of the guide spring pad, and the maximum diameter of the return spring (4) are all smaller than the internal diameter of the transverse large cylinder of the steering gear housing (1), the maximum diameter of the rack adjusting nut (6) is smaller than the minimum diameter of the housing adjusting nut (9), the rack adjusting nut (6) is provided with a hexagonal assembly feature (6c), the housing adjusting nut (9) is provided with a semicircular assembly feature (9a) at the minimum diameter, and the locking screw is provided with a tapered top feature (7b) and an internal hexagonal assembly feature (7c), and is locked in a deformed manner.

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