Corner limiting mechanism of drive-by-wire upper steering system

Abstract

The invention discloses a steering angle limiting mechanism of a drive-by-wire upper steering system. A rotating shaft is installed in a shell and driven by a road feeling simulation control unit to rotate, a rope penetrates through an outer cam, the two ends of the rope are connected with a retractor, a reset spring is installed in the outer cam, and an inner cam is fixed to the rotating shaft; a locking inner boss is formed on the inner ring of the outer cam, and a locking outer boss is formed on the outer ring of the inner cam; when the rotating angle of the rotating shaft does not reach the set angle, the rope is wound on the rotating shaft by the rotating shaft, and the outer cam is pressed on the end cover by the reset spring; when the rotating angle of the rotating shaft reaches a set angle, the rotating shaft tightens the rope, the outer cam is driven by the rope to move upwards to a limit position, and at the moment, the locking inner boss and the locking outer boss form stopping locking. The rotating shaft is used for winding the rope to meet the rotating angle requirement that the rotating angle is larger than 360 degrees in an upper steering system, meanwhile, the rope is used for dragging the outer cam to make contact with the inner cam finally to achieve tail end locking, and therefore the rotating torque of the tail end of a steering wheel is borne.

Description

Technical Field

[0001] This invention relates to vehicle steering systems, and more particularly to a steering angle limiting mechanism for the upper steering system in a steer-by-wire system. Background Technology

[0002] With the increasing maturity of intelligent driving technology, the application of fully autonomous driving technology is just around the corner. At that time, the steering operation of the car will be completely controlled by the onboard computer, so the steering wheel will be unnecessary when not being driven manually. However, the need for human intervention will still exist. Therefore, the emergence of a retractable drive-by-wire column assembly is an inevitable trend. This will provide steering operation function and also allow the drive-by-wire column assembly to be stored when not needed, providing more spacious space for the driver's seat.

[0003] The steer-by-wire column assembly is a subsystem of the automotive steer-by-wire system. Its main functions include providing power assist feedback to simulate road feel, offering mechanical rotational hard limits, collapsible energy absorption, adjusting steering wheel position, connecting to the vehicle's crossbeam, and connecting to the guard's combination switch. Currently, non-steer-by-wire systems typically use a motor-driven worm gear reduction mechanism to reduce torque. The upper and lower steering systems are connected via an intermediate shaft to achieve synchronized rotation.

[0004] Existing steer-by-wire systems lack an intermediate shaft between the upper and lower steering systems, and there is no mechanical connection between the steering wheel and the tires. They primarily rely on axial limits on the steering gear to control the steering wheel's rotation limits, but this makes it difficult to guarantee synchronous rotation of the steering wheel and locking at the end of the steering wheel. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a rotation limiting mechanism for a steer-by-wire system, which can solve the problem that the steer-by-wire system cannot control the rotation angle of the steering wheel and the end lock.

[0006] To solve the above problems, the present invention provides a steering angle limiting mechanism for a steer-by-wire system. The steer-by-wire system includes a steering shaft, a steer-by-wire column assembly, and a road feel simulation control unit. The steering angle limiting mechanism includes a housing, a rotating shaft, an inner cam, an outer cam, a rope, a retractor, a return spring, and an end cap. The housing is fixedly connected to the outer shell of the road feel simulation control unit. The rotating shaft is installed inside the housing and rotates under the drive of the road feel simulation input shaft of the road feel simulation control unit. The rope passes through the outer cam and is connected to the retractor at both ends. The return spring is installed in the outer cam and its upper end abuts against the housing. The inner cam is fixedly installed on the rotating shaft. The inner ring of the outer cam forms a locking inner boss, and the outer ring of the inner cam forms a locking outer boss. When the steering wheel drives the rotating shaft to rotate and the rotation angle of the rotating shaft does not reach the set angle, the rotating shaft will wrap the rope in its own annular groove, and the outer cam will press against the end cover under the action of the return spring. When the rotation angle of the rotating shaft reaches the set angle, the rotating shaft tightens the rope and the outer cam is driven upward by the rope until the outer cam rises to the limit position. At this time, the locking inner boss of the outer cam and the locking outer boss of the inner cam form a stop and lock.

[0007] Furthermore, the end cap is formed with a limiting rib, which, together with the return spring, keeps the outer cam in the set position when the rotation angle of the rotating shaft has not reached the set angle.

[0008] Furthermore, the outer ring of the outer cam is formed with a sliding boss, and the inner wall of the housing is formed with a groove that slides in cooperation with the sliding boss.

[0009] Furthermore, the outer cam has four evenly distributed sliding bosses.

[0010] Furthermore, the outer cam has four evenly distributed locking inner bosses, and the inner cam has four evenly distributed locking outer bosses.

[0011] Furthermore, the outer cam has through holes formed on two symmetrical locking inner bosses for ropes to pass through, and a stop block is provided below the through hole for the rope, the outer diameter of which is larger than the diameter of the through hole.

[0012] Furthermore, the retractor is equipped with two coil springs, one at each end of the rope, which keeps the rope in a taut state.

[0013] Furthermore, the return spring is in a compressed state.

[0014] Furthermore, the center of the inner cam is a waist-shaped hole that mates with the rotating shaft, and the rotating shaft is provided with a retaining spring below the inner cam to restrict the inner cam.

[0015] Compared with the prior art, the technical effects that the present invention can achieve are: First, the present invention utilizes the method of winding a rope around a rotating shaft to achieve the rotation angle requirement of more than 360° in the steer-by-wire system. This structure can easily achieve the adjustment of the rotation angle by setting the total length of the rope. Second, when the rotating shaft reaches the set end limit position, the invention will trigger the outer cam to move upward in the axial direction by means of rope traction and finally contact the inner cam on the rotating shaft to achieve end locking. This locking structure can withstand the rotational torque at the end of the steering wheel. Third, in this invention, only the locking structure consisting of the outer cam and the inner cam bears the rotational torque at the end of the steering wheel, and the rope does not participate in the locking, so a lighter rope can be used. Fourth, before the outer cam moves upward during rope traction, only the rotating shaft rotates and wraps the rope around itself. There is no movement of any other parts. Therefore, the NVH effect and friction torque effect are excellent throughout the process, and no abnormal noise is caused. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall components of a steer-by-wire system. Figure 2 This is a schematic diagram of the upper actuator assembly of a steer-by-wire system; Figure 3 This is an exploded view of the corner limiting mechanism of the present invention; Figure 4 This is a cross-sectional view of the corner limiting mechanism of the present invention in the non-locking state; Figure 5 This is a partially enlarged cross-sectional view of the corner limiting mechanism of the present invention in the non-locking state; Figure 6 This is a cross-sectional view of the corner limiting mechanism of the present invention in the locked state; Figure 7 This is a cross-sectional view of the corner limiting mechanism of the present invention in the locked state.

[0017] The accompanying diagrams are labeled as follows: 1 is the steering shaft; 2 is the drive-by-wire column assembly; 3 is the road feel simulation control unit; 4 is the connecting wiring harness; 5 is the reduction gear; 6 is the steering gear; 7 is the steering gear drive motor; 8 is the steering gear power assist control unit; 9 is the tie rod; 11 is the housing; 111 is the slide groove; 12 is the rotating shaft; 13 is the inner cam; 131 is the locking outer boss; 14 is the outer cam; 141 is the sliding boss; 142 is the locking inner boss; 143 is the annular groove; 144 is the through hole; 15 is the rope; 151 is the stop block; 16 is the retractor; 161 is the coil spring; 17 is the return spring; 18 is the end cap; 181 is the limiting rib; 19 is the retaining spring. Detailed Implementation

[0018] The embodiments of the present invention are described below with reference to the accompanying drawings and specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Specific details are set forth in the following description to provide a thorough understanding of the present invention; however, the present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be based on different viewpoints and applications. Those skilled in the art can make various similar extensions and substitutions without departing from the spirit of the present invention.

[0019] It should be noted that the terms "comprising," "having," and "forming," and any variations thereof, used in this invention, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps, units, or components not explicitly listed or inherent to these processes, methods, products, or devices. Furthermore, the terms "connected," "linked," "installed," and "equipped with," and their variations, used in this invention, merely indicate the assembly relationship of components. The connection method or connection structure between components can be designed and arranged by those skilled in the art as needed. In addition, the directional terms such as "upper," "lower," "middle," "inner," and "outer" mentioned herein are used based on the positional relationships of the structures in the accompanying drawings and do not constitute a limitation on the technical solution.

[0020] Currently, in online steering systems, the upper steering system and the lower steering system are not connected by an intermediate shaft, resulting in no mechanical hard connection between the steering wheel and the tires. The steering wheel rotation limit can only be controlled by the axial limit on the steering gear, but this cannot guarantee that the steering column assembly and the steering gear are synchronized.

[0021] Figure 1 The diagram shows a steer-by-wire system in a vehicle, including a steering shaft 1, a steer-by-wire column assembly 2, a road feel simulation control unit 3 (containing a controller and a road feel motor, not shown in the diagram), a wiring harness 4, a reduction gear 5, a steering gear 6, a steering gear drive motor 7, a steering gear power assist control unit 8, and a tie rod 9. The steering wheel is connected to the steering shaft 1 via a spline. When the driver applies torque (hereinafter referred to as hand force) to turn the steering wheel, it drives the steering shaft 1 to rotate. The steering shaft 1 is connected via a spline to the steering column shaft in the steer-by-wire column assembly 2. The steering column shaft is connected to the road feel simulation input shaft of the road feel simulation control unit 3, such as... Figure 3 As shown. The controller in the road feel simulation control unit 3 transmits the angle signal to the steering assist control unit 8 via the connecting harness 4. The steerable column assembly 2 and the steering gear 6 are connected only through the connecting harness 4. The steering assist control unit 8 drives the steering gear drive motor 7 to provide assistance based on the road load, pushing the rack in the steering gear 6 to move left and right, and then the tie rod 9 drives the tire to rotate to achieve steering. At the same time, the steering assist control unit 8 feeds back the road resistance to the controller in the road feel simulation control unit 3, calculates the matching feel torque according to the built-in software algorithm, and drives the road feel motor in the road feel simulation control unit 3 to provide resistance torque. After being reduced and amplified by the reduction mechanism 5, the torque is fed back to the steering wheel, so that the entire steerable column assembly can provide the driver with virtual road feedback.

[0022] like Figure 2As shown, the upper actuator assembly of the steer-by-wire system includes a steer-by-wire column assembly 2 and a road feel simulation control unit 3 (containing a controller and a road feel motor). The steering column shaft in the steer-by-wire column assembly 2 rotates with the steering wheel and is connected to the road feel simulation input shaft of the road feel simulation control unit 3 via an external spline connection. The road feel simulation input shaft drives the rotating shaft in the rotation limit mechanism to rotate, and after multiple rotations to the left and right, it contacts a mechanical hard limit and stops, thus achieving rotation limit. The road feel simulation control unit 3 and the steer-by-wire column assembly 2 are fastened together with screws.

[0023] The angle limiting mechanism in this embodiment, such as Figure 3 As shown, the system includes a housing 11, a rotating shaft 12, an inner cam 13, an outer cam 14, a rope 15, a retractor 16, a return spring 17, and an end cap 18. The housing 11 is fixedly connected to the outer shell of the road feel simulation control unit 3. The rotating shaft 12 is installed inside the housing 11 and rotates under the drive of the road feel simulation input shaft of the road feel simulation control unit 3. The rope 15 passes through the outer cam 14 and is connected to the retractor 16 at both ends. The return spring 17 is installed in the annular groove 143 of the outer cam 14 and its upper end abuts against the housing 11. The inner cam 13 is fixedly installed on the rotating shaft 12. The inner ring of the outer cam 14 forms a locking inner boss 142, and the outer ring of the inner cam 13 forms a locking outer boss 131.

[0024] When the steering wheel drives the rotating shaft 12 to rotate and the rotation angle of the rotating shaft 12 does not reach the set angle, the rotating shaft 12 wraps the rope 15 in its own annular groove, and the outer cam 14 is pressed against the end cover 18 under the action of the return spring 17.

[0025] When the rotation angle of the rotating shaft 12 reaches the set angle, the rotating shaft 12 tightens the rope 15 and the outer cam 14 is driven to move upward by the rope 15 until the outer cam 14 rises to the limit position. At this time, the locking inner boss 142 of the outer cam 14 and the locking outer boss 131 of the inner cam 13 form a stop lock.

[0026] like Figure 3 As shown, the end cap 18 forms a limiting rib 181. This limiting rib 181 and the return spring 17 work together to keep the outer cam 14 in a set position when the rotation angle of the rotating shaft 12 has not reached the set angle. At this time, there is a certain distance between the outer cam 14 and the inner cam 13 in the axial direction of the rotating shaft 12. Figure 4 , Figure 5 As shown, the outer cam 14 and the inner cam 13 are not on the same horizontal plane.

[0027] like Figure 3 , Figure 7As shown, the outer ring of the outer cam 14 has a sliding boss 141, and the inner wall of the housing 11 has a groove 111 that slides in conjunction with the sliding boss 141. The sliding boss 141 can slide up and down in the groove 111, while the housing 11 restricts the rotation of the outer boss 14. Preferably, the outer cam 14 has four evenly distributed sliding bosses 141.

[0028] like Figure 3 As shown, the outer cam 14 has four evenly distributed locking inner bosses 142, and the inner cam 13 has four evenly distributed locking outer bosses 131. The outer cam 14 has through holes 144 for the rope 15 to pass through on two symmetrical locking inner bosses 142, and a stop block 151 is provided below the through hole 144 for the rope 15. The outer diameter of the stop block is larger than the diameter of the through hole 144. Figure 3 , Figure 4 , Figure 5 As shown.

[0029] like Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 As shown, the retractor 16 is equipped with two coil springs 161, and each end of the rope 15 is connected to a coil spring 161, which keeps the rope 15 in a tightened state.

[0030] In this embodiment, the return spring 17 is in a compressed state. Before the rope 15 pulls the outer cam 14 upward, the return spring 17 is used to press the outer cam 14 onto the end cap 18 so that the outer cam 14 will not move in the axial direction.

[0031] like Figure 3 , Figure 7 As shown, the center of the inner cam 13 is an oblong hole that mates with the rotating shaft 12, and the rotating shaft 12 is provided with a retaining spring 19 below the inner cam 13 to restrict the inner cam 13, as shown. Figure 4 , Figure 5 As shown, the inner cam 13 always rotates synchronously with the rotating shaft 12.

[0032] like Figure 4 , Figure 5 As shown, when the steering wheel drives the rotating shaft 12 to rotate via the steering shaft 1, steering column shaft, and road feel simulation input shaft, and the rotation angle of the rotating shaft has not reached the set angle (e.g., ±540°), the rotating shaft 12 rotates while simultaneously winding the rope 15 around its own annular groove. The rotation angle of the rotating shaft 12 depends on the length of the rope 15; that is, the length of the rope 15 can be adjusted to obtain the desired rotation angle of the rotating shaft. As the rotation angle of the rotating shaft 12 increases, the rope 15 will gradually tighten.

[0033] The lower end of the rope 15 is connected to the coil spring 161 of the retractor 16. As long as there is any gap in the free state, the rope 15 will be wound up by the retractor 16, and the coil spring 161 will tighten the posture of the rope 15 to ensure that the posture of the parts is controllable.

[0034] The top of the outer cam 14 is pressed by the return spring 17, and the bottom is supported by the protruding limiting rib 181 on the end cover 18, thus determining the spatial position of the outer cam 14 in the non-locked state.

[0035] When the steering wheel drive shaft 12 rotates to a set angle (e.g., ±540°), the shaft 12 begins to tighten the rope 15, and the rope 15 pulls the outer cam 14 upward until the rope 15 pulls the outer cam 14 to its upper limit position. Figure 6 As shown. At this time, as Figure 7 As shown, the four locking inner bosses 142 of the outer cam 14 and the four locking outer bosses 131 of the inner cam 13 form a stop to achieve end locking. This stop structure can stop rotational torque exceeding 150 Nm from the steering wheel at the end, and can withstand a maximum rotational torque of 200 Nm. In the locking structure, the rope 15 does not need to bear rotational torque, so the rope 15 can be made of a lighter nylon rope. For example, using a nylon rope with a diameter of 1.2 mm can ensure a breaking strength of 200 N. In the entire working system, the working tensile force of the rope 15 is only used to overcome the friction of the outer cam 14 in the housing groove, which is only about 5 N, while the breaking strength of the nylon rope is 40 times or even higher than that under working conditions.

[0036] When the end is locked, the steering wheel is turned in the opposite direction. At this time, the outer cam 14 will be pressed down and reset under the action of the return spring 17, and finally return to the initial state before locking. That is, the lower end face of the outer cam 14 presses on the limiting rib 181 of the end cover 18, and the upper end face of the outer cam 14 will be pressed by the return spring 17.

[0037] During the entire process before the outer cam 14 is pulled upward by the rope 15, only the rotating shaft 12 rotates while the rope 15 is wound around itself. There is no movement of any other parts, so the NVH effect and friction torque effect are excellent throughout the process, and no abnormal noise is caused. When the outer cam 14 is pulled upward by the rope 15, it is only triggered by the rotation angle at the end of the rotating shaft, such as ±540° or ±575°. There is no triggering mechanism in the middle section. The set angle (540°, 575°) is usually hidden at the end of the soft limit (the limit is implemented by software), so it is not easy to perceive the fluctuation of the feel or the abnormality of NVH.

[0038] The present invention has been described in detail above through specific embodiments. The above embodiments are merely preferred embodiments of the present invention, and the present invention is not limited to the above-described embodiments. Without departing from the principle of the present invention, equivalent substitutions and improvements made by those skilled in the art to the fitting method of the rotating shaft and the housing, as well as the shape and structure of the inner cam, outer cam, and rotating shaft, should all be considered within the technical scope protected by the present invention.

Claims

1. A steering angle limiting mechanism for a steer-by-wire system, the steer-by-wire system comprising a steering shaft, a steer-by-wire column assembly, and a road feel simulation control unit, characterized in that, The device includes a housing, a rotating shaft, an inner cam, an outer cam, a rope, a retractor, a return spring, and an end cap. The housing is fixedly connected to the outer shell of the road sense simulation control unit. The rotating shaft is installed inside the housing and rotates under the drive of the road sense simulation input shaft of the road sense simulation control unit. The rope passes through the outer cam and is connected to the retractor at both ends. The return spring is installed in the outer cam and its upper end abuts against the housing. The inner cam is fixedly installed on the rotating shaft. The inner ring of the outer cam forms a locking inner boss, and the outer ring of the inner cam forms a locking outer boss. When the steering wheel drives the rotating shaft to rotate and the rotation angle of the rotating shaft does not reach the set angle, the rotating shaft will wrap the rope in its own annular groove, and the outer cam will press against the end cover under the action of the return spring. When the rotation angle of the rotating shaft reaches the set angle, the rotating shaft tightens the rope and the outer cam is driven upward by the rope until the outer cam rises to the limit position. At this time, the locking inner boss of the outer cam and the locking outer boss of the inner cam form a stop and lock.

2. The steering angle limiting mechanism of the steer-by-wire system according to claim 1, characterized in that, The end cap forms a limiting rib, which, together with the return spring, keeps the outer cam in the set position when the rotation angle of the rotating shaft has not reached the set angle.

3. The steering angle limiting mechanism of the steer-by-wire system according to claim 1, characterized in that, The outer ring of the outer cam has a sliding boss, and the inner wall of the housing has a groove that slides in conjunction with the sliding boss.

4. The steering angle limiting mechanism of the steer-by-wire system according to claim 3, characterized in that, The outer cam has four evenly distributed sliding bosses.

5. The steering angle limiting mechanism of the steer-by-wire system according to claim 1, characterized in that, The outer cam has four evenly distributed locking inner bosses, and the inner cam has four evenly distributed locking outer bosses.

6. The steering angle limiting mechanism of the steer-by-wire system according to claim 5, characterized in that, The outer cam has through holes formed on two symmetrical locking inner bosses for ropes to pass through, and a stop block is provided below the through hole for the rope, the outer diameter of which is larger than the diameter of the through hole.

7. The steering angle limiting mechanism of the steer-by-wire system according to claim 1, characterized in that, The retractor has two coil springs, one at each end of the rope, which keeps the rope in a taut state.

8. The steering angle limiting mechanism of the steer-by-wire system according to claim 1, characterized in that, The return spring is in a compressed state.

9. The steering angle limiting mechanism of the steer-by-wire system according to claim 1, characterized in that, The center of the inner cam is a waist-shaped hole that mates with the rotating shaft, and the rotating shaft is provided with a retaining spring below the inner cam to restrict the inner cam.

Images