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

Abstract

The invention discloses a rotation limiting mechanism of a drive-by-wire upper steering system, which is characterized in that a shell is fixedly connected with a shell of a road feeling simulation control unit, and a rotating shaft is arranged in the shell and is driven by a road feeling simulation input shaft of the road feeling simulation control unit to rotate; the sliding cam is driven by the rotating shaft to rotate with the axis of the rotating shaft as the center and axially translate in the axis direction, the locking cam is fixed to the lower end of the rotating shaft, an inner boss and an outer boss are formed on the sliding cam, a sliding groove matched with the outer boss is formed in the inner wall of the shell, a limiting boss is formed on the rotating shaft, and a locking boss is formed on the locking cam. When the sliding cam moves to the upper tail end of the rotating shaft, the limiting boss of the rotating shaft makes contact with the inner boss of the sliding cam to form upper locking, and when the sliding cam moves to the lower tail end of the rotating shaft, the inner boss of the sliding cam makes contact with the locking boss of the locking cam to form lower locking. The cable control column assembly can rotate by a required angle, and the tail end can be locked.

Description

Technical Field

[0001] This invention relates to vehicle steering systems, and more particularly to a rotation 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 address the aforementioned problems, this invention provides a rotation 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 rotation limiting mechanism includes a housing, a rotating shaft, a sliding cam, and a locking cam. 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 sliding cam rotates around the axis of the rotating shaft under the drive of the rotating shaft and simultaneously translates vertically along the axial direction. The locking cam is fixedly installed at the lower end of the rotating shaft. The inner ring of the sliding cam has an inner boss, and the outer ring has an outer boss. The inner wall of the housing has a groove that mates with the outer boss of the sliding cam. The rotating shaft has a limiting boss, and the locking cam has a locking boss. When the sliding cam moves to the upper end of the rotating shaft, the limiting boss of the rotating shaft contacts the inner boss of the sliding cam to form an upper lock. When the sliding cam moves to the lower end of the rotating shaft, the inner boss of the sliding cam contacts the locking boss of the locking cam to form a lower lock.

[0007] Furthermore, the rotating shaft has a threaded guide area, the middle part of which is a small-pitch thread, and the upper and lower parts are large-pitch threads. The switching position between the small-pitch thread and the upper large-pitch thread is the upper inflection point, and the switching position between the small-pitch thread and the lower large-pitch thread is the lower inflection point.

[0008] Furthermore, the limiting boss of the rotating shaft is located above the threaded guide area, and the locking cam is located below the threaded guide area.

[0009] Furthermore, the inner wall of the sliding cam is also formed with a guide pin, which slides along the threaded guide groove of the threaded guide area.

[0010] Furthermore, the sliding cam also forms a mounting groove for mounting an O-ring.

[0011] Furthermore, the mechanism also includes a lower end cover, which is threadedly connected to the housing, and the lower end cover has an assembly groove for installing an O-ring.

[0012] Furthermore, the rotating shaft is rotatably mounted inside the housing via bearings.

[0013] Furthermore, the center of the locking cam has a waist-shaped hole that mates with the lower end of the rotating shaft.

[0014] Furthermore, a retaining ring for limiting the locking cam is installed on the rotating shaft, and the retaining ring is located below the locking cam.

[0015] Furthermore, the inner and outer bosses of the sliding cam, the limiting boss of the rotating shaft, and the locking boss of the locking cam are all four and evenly distributed.

[0016] Compared with the prior art, the technical effects that the present invention can achieve are: First, the present invention utilizes a rotating shaft with a variable pitch threaded guide structure to drive a sliding cam to rotate around the central axis of the rotating shaft while simultaneously moving axially up and down along the threaded guide groove on the rotating shaft. By adjusting the length of the threaded guide groove, the steer-by-wire column can complete the required rotation angle of more than 360° within a limited space. Second, the present invention has an inner boss and an outer boss formed on the sliding cam, a limiting boss formed on the upper part of the rotating shaft, and a locking cam formed on the lower end of the rotating shaft. At the same time, a sliding groove is formed on the inner wall of the housing to cooperate with the outer boss of the sliding cam. When the sliding cam moves up to the upper end of the rotating shaft, the inner boss of the sliding cam contacts the limiting boss of the rotating shaft to achieve upper locking, and the outer boss of the sliding cam locks with the housing to restrict the rotation of the rotating shaft. When the sliding cam moves down to the lower end of the rotating shaft, the inner boss of the sliding cam contacts the locking boss of the locking cam to achieve lower locking, thereby achieving effective end-point stopping. Third, the rotating shaft of the present invention adopts a guide groove with a variable pitch thread. The middle section adopts a small pitch thread guide groove to save axial space, and the two ends adopt a large pitch thread guide groove to enable the sliding cam to move quickly to the upper and lower ends in the direction of the rotating shaft axis when the steering wheel rotates to the limit position and a small angle rotation occurs to complete the contact of the corresponding bosses, thereby achieving end locking. Fourth, the sliding cam, locking cam, and locking structure of the rotating shaft of the present invention are all provided with four bosses, which can withstand the rotational torque when the end of the steering wheel is locked. Attached Figure Description

[0017] 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 a schematic diagram showing the position of the rotary limiting mechanism of the present invention in the upper actuator assembly; Figure 4 This is an exploded view of the rotation limiting mechanism of the present invention; Figure 5 This is a schematic diagram of the rotating shaft in the rotating limiting mechanism of the present invention; Figure 6 This is a three-dimensional schematic diagram of the sliding cam in the rotation limiting mechanism of the present invention; Figure 7a , Figure 7b This is a diagram showing the positional relationship of the sliding cam in the rotary limiting mechanism when it reaches the upper inflection point of the rotating shaft. Figure 8a , Figure 8bThis is a schematic diagram showing the locking mechanism when the sliding cam reaches the upper end position of the rotating shaft in the rotary limiting mechanism. Figure 9a , Figure 9b This is a diagram showing the positional relationship of the sliding cam in the rotary limiting mechanism when it reaches the lower inflection point of the rotating shaft. Figure 10a , Figure 10b This is a schematic diagram showing the locking mechanism when the sliding cam reaches the lower end of the rotating shaft in a rotary limiting mechanism.

[0018] The accompanying diagrams are labeled as follows: 1 is the steering shaft; 2 is the drive-by-wire column assembly; 21 is the steering column shaft; 3 is the road feel simulation control unit; 31 is the road feel simulation input shaft; 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 limiting slot; 12 is the rotating shaft; 121 is the limiting boss; 122 is the threaded guide groove; 123 is the upper inflection point; 124 is the lower inflection point; 13 is the sliding cam; 131 is the inner boss; 132 is the guide pin; 133 is the outer boss; 134 is the assembly groove; 14 is the locking cam; 141 is the locking boss; 15 is the lower end cover; 16 is the first O-ring; 17 is the second O-ring; 18 is the retaining spring. Detailed Implementation

[0019] 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.

[0020] 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. Example

[0021] 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.

[0022] 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 21 in the steer-by-wire column assembly 2. The steering column shaft 21 is connected to the road feel simulation input shaft 31 of the road feel simulation control unit 3. 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.

[0023] like Figure 2, Figure 3 As 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 21 in the steer-by-wire column assembly 2 rotates with the steering wheel and is externally splinedly connected to the road feel simulation input shaft 31 of the road feel simulation control unit 3. The road feel simulation input shaft 31 drives the rotating shaft in the rotation limit mechanism to rotate, and after multiple rotations to the left and right, it contacts the mechanical hard limit and stops, achieving rotation limit. The road feel simulation control unit 3 and the steer-by-wire column assembly 2 are fastened together with screws.

[0024] The rotation limiting mechanism of the steer-by-wire system in this embodiment, such as Figure 4 As shown, the system includes a housing 11, a rotating shaft 12, a sliding cam 13, and a locking cam 14. The housing 11 is fixedly connected to the outer shell of the road feel simulation control unit 3. The rotating shaft 12 is rotatably mounted inside the housing 11 via bearings and rotates under the drive of the road feel simulation input shaft 31 of the road feel simulation control unit 3. Driven by the rotating shaft 12, the sliding cam 13 rotates around the axis of the rotating shaft 12 and simultaneously translates vertically along the axial direction. The locking cam 14 is fixedly mounted on the lower end of the rotating shaft 12. The inner ring of the sliding cam 13 has an inner boss 131, and the outer ring has an outer boss 133. The inner wall of the housing 11 has a groove that mates with the outer boss 133 of the sliding cam 13. The rotating shaft 12 has a limiting boss 121, and the locking cam 14 has a locking boss 141. When the sliding cam 13 moves to the upper end of the rotating shaft 12, the limiting boss 121 of the rotating shaft 12 contacts the inner boss 131 of the sliding cam 13 to form an upper lock. When the sliding cam 13 moves to the lower end of the rotating shaft 12, the inner boss 131 of the sliding cam 13 contacts the locking boss 141 of the locking cam 14 to form a lower lock.

[0025] like Figure 5 As shown, the rotating shaft 12 forms a threaded guide region with variable pitch. The middle part of the threaded guide region has a small-pitch thread, while the upper and lower parts have large-pitch threads. The switching position between the small-pitch thread and the upper large-pitch thread is the upper inflection point 123, and the switching position between the small-pitch thread and the lower large-pitch thread is the lower inflection point 124. The limiting boss 121 of the rotating shaft 12 is located above the threaded guide region, and the locking cam 14 is installed below the threaded guide region.

[0026] like Figure 6 As shown, the inner wall of the sliding cam 13 is also formed with a guide pin 132, which slides along the threaded guide groove 122 of the threaded guide area.

[0027] like Figure 4As shown, the center of the locking cam 14 has an oblong hole that mates with the lower end of the rotating shaft 12. A retaining ring 18 is mounted on the rotating shaft 12 to restrict the locking cam 14, and the retaining ring 18 is located below the locking cam 14.

[0028] When the steering wheel is turned clockwise, the steering shaft 1 also rotates clockwise, thereby driving the steering column shaft 21, the road feel simulation input shaft 31, and the rotating shaft 12 to rotate. The rotating shaft 12, mounted in the housing 11 via bearings, rotates through the threaded guide groove 122 and the guide pin 132 of the sliding cam 13 located within the threaded guide groove 122. This drives the sliding cam 13 to rotate around the central axis of the rotating shaft 12 while simultaneously performing an axial translational upward movement on the rotating shaft 12, until the sliding cam 13 moves to the upper inflection point 123 of the rotating shaft 12. Figure 7a , Figure 7b As shown, at this time, the inner boss 131 of the sliding cam 13 does not contact the limiting boss 121 of the rotating shaft 12.

[0029] Before reaching the upper inflection point 123, the sliding cam 13 moves along a path of slow, constant pitch as it rises. After passing the upper inflection point 123, the sliding cam 13 rises rapidly through the large-pitch threaded guide groove, thus achieving a large axial upward movement with a small-angle rotation. The axial displacement rapidly gained by the sliding cam 13 during its movement from the upper inflection point 123 to the upper end position is the axial overlap of the end lock, thereby improving the reliability and strength of the end lock. Figure 8a , Figure 8b As shown, the sliding cam 13 moves to the upper end position of the rotating shaft 12. At this time, the limiting boss 121 of the rotating shaft 12 contacts the inner boss 131 of the sliding cam 13 to lock the boss. At the same time, the sliding groove of the housing 11 locks the outer boss 133 of the sliding cam 13, thus preventing the rotating shaft 12 from rotating.

[0030] When the steering wheel starts to rotate counterclockwise from its clockwise end position, the steering shaft 1 also rotates counterclockwise, thereby driving the steering column shaft 21, the road feel simulation input shaft 31, and the rotating shaft 12 to rotate counterclockwise. During the rotation, the rotating shaft 12 drives the sliding cam 13 to rotate around the central axis of the rotating shaft 12 while simultaneously performing an axial translational downward motion on the rotating shaft 12, until the sliding cam 13 moves down to the lower inflection point position 124 of the rotating shaft 12. Figure 9a , Figure 9b As shown, at this time, the inner boss 131 of the sliding cam 13 and the limiting boss 141 of the locking cam 14 do not come into contact.

[0031] After the sliding cam 13 passes the lower inflection point 124, it descends rapidly through the large-pitch threaded guide groove, thus achieving a large axial downward movement with a small-angle rotation. Similarly, the axial displacement rapidly gained by the sliding cam 13 as it moves from the lower inflection point 124 to the lower end position is the axial overlap of the end lock, improving the reliability and strength of the end lock. Figure 10a , Figure 10b As shown, the sliding cam 13 moves to the lower end position of the rotating shaft 12. At this time, the locking boss 141 of the locking cam 14 contacts the inner boss 131 of the sliding cam 13 to lock. At the same time, the sliding groove of the housing 11 locks with the outer boss 133 of the sliding cam 13, thus preventing the rotating shaft 12 from rotating.

[0032] In this embodiment, the rotating shaft drives the sliding cam to rotate around the central axis of the rotating shaft while simultaneously moving axially up and down along the threaded guide groove on the rotating shaft. By adjusting the length of the threaded guide groove, the steer-by-wire column can complete the required rotation angle of more than 360° within a limited space.

[0033] Meanwhile, this embodiment employs a guide groove with a variable pitch thread. The middle section uses a small pitch thread guide groove, which not only saves axial space but also allows for different numbers of turns to be designed as needed, thereby meeting the required number of rotations of the rotating shaft. The two ends use large pitch thread guide grooves, which enable the sliding cam to move quickly along the axis of the rotating shaft to the upper and lower ends to complete the contact with the corresponding bosses when the steering wheel rotates close to its limit position, thus achieving end locking.

[0034] like Figure 7b , Figure 8b , Figure 9b and Figure 10b As shown, the inner boss 131 and outer boss 133 of the sliding cam 13, the limiting boss 121 of the rotating shaft 12, and the locking boss 141 of the locking cam 14 are all four and evenly distributed. This type of end stop surface can withstand the rotational torque when the steering wheel is locked, and can withstand a maximum rotational torque of 200 N*m. Example

[0035] Based on Embodiment 1, this embodiment further optimizes the structure of the locking position.

[0036] Specifically, such as Figure 8b , Figure 10b As shown, the sliding cam 13 also forms an assembly groove 134 for mounting the first O-ring 16. Meanwhile, the rotation limiting mechanism also includes a lower end cover 15, which is threadedly connected to the housing 11, and the lower end cover 15 forms an assembly groove for mounting the second O-ring 17.

[0037] As the sliding cam 13 moves from the upper inflection point 123 to the upper end of the rotating shaft 12, as... Figure 8a As shown, the first O-ring 16 installed in the sliding cam 13 first contacts the housing 11. Only after the first O-ring 16 is flattened can the sliding cam 13 contact the rotating shaft 12 to complete the locking. Similarly, as the sliding cam 13 moves down from the lower inflection point 124 to the lower end of the rotating shaft 12, as... Figure 10a As shown, the sliding cam 13 first contacts the second O-ring 17. Only after the second O-ring 17 is flattened can the sliding cam 13 contact the locking cam 14 to complete the locking. The two O-rings can effectively avoid the noise caused by the end impact and improve driving comfort.

[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. Any equivalent substitutions and improvements made by those skilled in the art to the fit between the rotating shaft and the housing, the shape and structure of the sliding cam, the locking cam, and the rotating shaft, etc., without departing from the principle of the present invention, should be considered within the technical scope protected by the present invention.

Claims

1. A rotation limiting mechanism for a steer-by-wire upper steering system, the upper steering system comprising a steering shaft, a steer-by-wire column assembly, and a road feel simulation control unit, characterized in that, The system includes a housing, a rotating shaft, a sliding cam, and a locking cam. 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 sliding cam rotates around the axis of the rotating shaft under the drive of the rotating shaft and simultaneously translates vertically along the axis. The locking cam is fixedly installed at the lower end of the rotating shaft. The inner ring of the sliding cam has an inner boss, and the outer ring has an outer boss. The inner wall of the housing has a groove that mates with the outer boss of the sliding cam. The rotating shaft has a limiting boss, and the locking cam has a locking boss. When the sliding cam moves to the upper end of the rotating shaft, the limiting boss of the rotating shaft contacts the inner boss of the sliding cam to form an upper lock. When the sliding cam moves to the lower end of the rotating shaft, the inner boss of the sliding cam contacts the locking boss of the locking cam to form a lower lock.

2. The rotation limiting mechanism of the steer-by-wire system according to claim 1, characterized in that, The rotating shaft has a threaded guide area. The middle part of the threaded guide area is a small-pitch thread, while the upper and lower parts are large-pitch threads. The switching position between the small-pitch thread and the upper large-pitch thread is the upper inflection point, and the switching position between the small-pitch thread and the lower large-pitch thread is the lower inflection point.

3. The rotation limiting mechanism of the steer-by-wire system according to claim 2, characterized in that, The limiting boss of the rotating shaft is located above the threaded guide area, and the locking cam is located below the threaded guide area.

4. The rotation limiting mechanism of the steer-by-wire system according to claim 2, characterized in that, The inner wall of the sliding cam is also formed with a guide pin, which slides along the threaded guide groove of the threaded guide area.

5. The rotation limiting mechanism of the steer-by-wire system according to claim 1, characterized in that, The sliding cam also forms a mounting groove for mounting an O-ring.

6. The rotation limiting mechanism of the steer-by-wire system according to claim 1, characterized in that, The mechanism also includes a lower end cover, which is threadedly connected to the housing, and the lower end cover has an assembly groove for installing an O-ring.

7. The rotation limiting mechanism of the steer-by-wire system according to claim 1, characterized in that, The rotating shaft is rotatably mounted inside the housing via bearings.

8. The rotation limiting mechanism of the steer-by-wire system according to claim 1, characterized in that, The center of the locking cam has a waist-shaped hole that mates with the lower end of the rotating shaft.

9. The rotation limiting mechanism of the steer-by-wire system according to claim 8, characterized in that, A retaining ring is mounted on the rotating shaft to limit the locking cam, and the retaining ring is located below the locking cam.

10. The rotation limiting mechanism of the steer-by-wire system according to claim 1, characterized in that, The sliding cam has four inner and outer bosses, the rotating shaft has four limiting bosses, and the locking cam has four locking bosses that are evenly distributed.

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