Planetary roller screw rod self-locking structure

Abstract

A planetary roller screw rod self-locking structure comprises a screw rod shaft and a nut assembly which is arranged on the screw rod shaft in a sleeving mode and moves along with the screw rod shaft, and further comprises two one-way bearings which are arranged on the two sides of the nut assembly respectively, the two one-way bearings allow different rotation directions, and the linear distance between the two one-way bearings is larger than the width of the nut assembly. The nut assembly can be matched with the one-way bearing on one side to form synchronous rotation, and when the nut assembly generates a reverse movement trend, the one-way bearing can prevent the reverse movement trend from occurring. The nut assembly has the advantages that the linear distance between the one-way bearings located on the two sides of the nut assembly is larger than the width of the nut assembly, and therefore the nut assembly can only form matched synchronous rotation with the one-way bearing on one side during rotation; and when the motor stops outputting, the movement trend of reverse rotation generated by the nut assembly can be absorbed by the one-way bearing matched with the nut assembly on the side, so that reverse movement of the nut assembly is prevented.

Description

Technical Field

[0001] The utility model relates to a self-locking structure, in particular to a planetary roller screw self-locking structure. Background Art

[0002] Rear Wheel Steering (RWS) is an advanced automotive steering technology that enhances vehicle handling, stability, and agility by varying the steering angle of the rear wheels. The introduction of this technology marks a significant advancement in vehicle dynamics and handling. The importance of ball screw self-locking in rear wheel steering systems is reflected in the following aspects:

[0003] To ensure system stability, the ball screw self-locking function ensures that in a rear-wheel steering system, the rear wheels remain in a certain position under specific conditions, preventing unnecessary movement due to external forces or minor disturbances within the system. This is crucial for maintaining vehicle stability and controllability during driving.

[0004] To improve safety, rear-wheel steering systems may need to maintain a specific steering angle to accommodate certain driving conditions (such as parking). The self-locking function of the ball screw prevents the rear wheels from rotating unexpectedly without external power input, thereby avoiding possible accidents.

[0005] Chinese patent document CN117261998A discloses a rear-wheel steering gear and a vehicle having the same, which includes: a housing; a screw-nut mechanism, which is used to convert the rotational motion of the output shaft of the drive motor into axial linear motion of the screw spindle by the screw nut; a ball bearing, which is arranged between the sleeve and the housing; a locking mechanism, which includes a first locking assembly and a second locking assembly, the first locking assembly being connected to the end of the sleeve, the first locking assembly being used to provide an axial pre-tightening force for the screw-nut mechanism to eliminate the axial assembly clearance of the screw-nut mechanism, a part of the second locking assembly being connected to the end of the sleeve, and the other part of the second locking assembly being connected to the housing, and the second locking assembly being used to provide a limit for the axial freedom of movement at both ends of the ball bearing.

[0006] While the above solution simplifies the rear-wheel steering gear structure as much as possible, it has the following drawbacks: First, the second locking assembly is located at both axial ends of the ball bearing, meaning that the locking force acts on both ends of the ball bearing and is then transmitted to the nut, which reduces transmission and locking efficiency. Second, the existing technology cannot prevent the nut from rotating, that is, it cannot prevent the moving part from reversing. Utility Model Content

[0007] In view of the deficiencies in the prior art, the utility model provides a planetary roller screw self-locking structure which has a better self-locking effect and can prevent the nut from reversing.

[0008] To achieve the above-mentioned purpose, the technical solution of the utility model is as follows: a planetary roller screw self-locking structure, including a screw shaft and a nut assembly sleeved on the screw shaft and moving with the screw shaft, and also including two one-way bearings respectively arranged on both sides of the nut assembly. The two one-way bearings allow different rotation directions, and the straight-line distance between the two one-way bearings is greater than the width of the nut assembly. The nut assembly can cooperate with the one-way bearing on one side to form synchronous rotation and when the nut assembly generates a reverse motion trend, the one-way bearing is used to prevent the reverse motion trend from occurring.

[0009] The beneficial effects of this utility model are as follows: the linear distance between the one-way bearings on both sides of the nut assembly is greater than the width of the nut assembly itself, so that when the nut assembly rotates, it can only form a synchronous rotation with the one-way bearing on one side. When the motor stops outputting, the reverse rotation movement of the nut assembly is absorbed by the one-way bearing on that side, thereby preventing the nut assembly from reverse movement. Secondly, because the one-way bearing can directly apply the locking force to the nut assembly, the transmission efficiency is effectively improved.

[0010] Furthermore, the one-way bearing includes an inner ring whose inner diameter surface is conically set, and the nut assembly includes a nut and nut end covers arranged on both sides of the nut and fixed to the nuts respectively, and the nut end cover is provided with a stop ring with a conical cross-section facing the one-way bearing opposite to it.

[0011] The one-way bearing inner ring and the retaining ring, which have matching shapes and conical cross-sections, make it easier for the nut assembly to drive the one-way bearing on that side to operate. When the nut assembly has a tendency to reverse, greater friction can be generated between the retaining ring, which has a conical cross-section and the one-way bearing inner ring, so that the one-way bearing can better absorb the reverse movement trend of the nut assembly to prevent the nut assembly from reversing.

[0012] Furthermore, a plurality of circumferentially distributed stopping grooves are provided on the outer surface of each stopping ring, and the plurality of stopping grooves extend spirally on the outer surface of the stopping ring, and the spiral extension direction is opposite to the rotation direction allowed by the one-way bearing on that side.

[0013] Several retaining grooves extending in a spiral shape on the outer surface of the retaining ring can generate greater friction to prevent the nut assembly from reversing when the nut assembly has a tendency to reverse movement; similarly, the spiral extension direction formed by the several retaining grooves is opposite to the rotation direction allowed by the one-way bearing on that side, which can further increase the friction between the nut end cover and the one-way bearing when the nut assembly has a tendency to reverse.

[0014] Furthermore, a stopping bead is provided in each of the stopping grooves, and the depth of the stopping groove gradually decreases in the rotation direction allowed by the one-way bearing on that side.

[0015] During the process of the nut assembly moving toward the one-way bearing on one side and gradually forming a synchronous rotation relationship with the one-way bearing, the stop bead gradually moves in the stop groove and at this time the distance between the stop groove and the inner ring of the one-way bearing gradually decreases, so that the stop bead rests between the two, thereby better allowing the nut end cover to drive the one-way bearing on that side to rotate. And when the nut assembly has a reverse trend, the stop bead can also play a certain braking role to better avoid the possibility of the nut assembly moving in the opposite direction. In addition, the difference between the straight-line distance between the two one-way bearings and the width of the nut assembly is smaller than the width of a single stop groove projected on the axis, so that the stop bead is always between the stop ring and the inner ring of the one-way bearing. As a preferred embodiment, the cross-section of the stop groove can be set to be above the center line of the stop bead and in an enclosing shape to further prevent the stop bead from falling out.

[0016] Furthermore, a wave washer is provided between the one-way bearing and the nut end cover on each side.

[0017] The wave washer can effectively prevent the nut end cover from misalignment when the nut end cover and the one-way bearing on the same side form a synchronous rotation relationship, so as to achieve a better rotation relationship between the two; secondly, when the nut end cover withdraws from the one-way bearing on the same side, the wave washer can provide a certain pushing force to enable the nut end cover to better withdraw from the one-way bearing on that side and move. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is an axonometric diagram of an embodiment of the present utility model;

[0019] Figure 2 A cross-sectional view of an embodiment of the present utility model;

[0020] Figure 3 This is a disassembly diagram of an embodiment of the utility model;

[0021] Figure 4 This is a front view of the nut end cover of an embodiment of the utility model;

[0022] Figure 5 This is a partial enlarged view of the retaining groove of an embodiment of the present utility model. DETAILED DESCRIPTION

[0023] The utility model embodiment of a planetary roller screw self-locking structure is as follows Figure 1-5As shown: it includes a screw shaft 1 and a nut assembly 2 that is sleeved on the screw shaft 1 and drives the screw shaft 1 to move through a motor (not shown in the figure). One-way bearings 3 are respectively provided on both sides of the nut assembly 2. The straight-line distance between the two one-way bearings 3 is greater than the width of the nut assembly 2 itself, that is, the nut assembly 2 can move between the two one-way bearings 3 and when the nut assembly 2 abuts against the one-way bearing 3 on one side, it will not abut against the one-way bearing 3 on the other side. The two one-way bearings 3 allow different directions of rotation. In this embodiment, combined with the accompanying drawings, the one-way bearing 3 on the left side can allow right rotation, but not left rotation, while the one-way bearing 3 on the opposite side is the opposite. How the one-way bearing 3 achieves one-way rotation belongs to the existing technology and will not be elaborated here.

[0024] The nut assembly 2 comprises a nut 21 that fits over the screw shaft 1, a nut end cap 22 secured to the outside of the nut, and two nut end caps 22 located on either side of the nut 21 and secured to the nut end cap 22. Drive teeth 231 are located in the center of the nut housing 23, which mate with the drive belt of a motor (not shown). Each nut end cap 22 is provided with a stop ring 221, facing the inner ring 31 of the one-way bearing 3 on the same side. The outer surface of the stop ring 221 mates with the inner diameter of the inner ring 31 of the one-way bearing 3 and has a conical cross-section. Several stop grooves 2211 are provided on the outer surface of the stop ring 221. These grooves 2211 extend helically on the outer surface of the stop ring 221, and the direction of this helical extension is opposite to the permitted rotation direction of the one-way bearing 3 on the same side of each nut end cap 22. A retaining bead 2212 is also provided in the retaining groove 2211, and the depth of the retaining groove 2211 gradually decreases in the rotation direction allowed by the one-way bearing on the same side as the nut end cap 22. In addition, a wave washer 4 is provided between the one-way bearing and the nut end cap on each side.

[0025] The following is a brief description of the use of this embodiment, with reference to the accompanying drawings: When the motor (not shown) drives the nut assembly 2 to rotate, thereby driving the screw shaft 1 toward the right, causing the right nut end cap 22 to gradually abut against the right one-way bearing 3. During this abutment process, the wave washer 4 can correct the position and preload the position. As the stop ring 221 is inserted into the inner diameter surface of the inner ring 31 of the one-way bearing 3, the stop bead 2212 moves within the stop groove 2211 and gradually moves to a shallower position in the stop groove 2211, thereby forming a close abutment relationship with the inner ring 31 of the one-way bearing 3, thereby establishing a synchronous rotation relationship between the nut assembly 2 and the right one-way bearing 3.

[0026] When the motor (not shown in the figure) is powered off, it will cause the nut assembly 2 to have a reverse tendency. At this time, the one-way bearing 3 on the right is not allowed to rotate left, and since the stopping bead 2212 is stuck between the one-way bearing 3 and the nut end cover 22, the superimposed stopping ring 221 and the stopping groove 2211 arranged on the outer surface of the stopping ring 221 can effectively absorb the reverse rotation tendency of the nut assembly 2 and prevent it from rotating in the reverse direction.

[0027] The above embodiment is only one preferred embodiment of the present invention. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention are all included in the protection scope of the present invention.

Claims

1. A planetary roller screw self-locking structure, comprising a screw shaft and a nut assembly sleeved on the screw shaft and used to drive the screw shaft to move, characterized in that: It also includes two one-way bearings respectively arranged on both sides of the nut assembly. The two one-way bearings allow different rotation directions. The straight-line distance between the two one-way bearings is greater than the width of the nut assembly. The nut assembly can cooperate with the one-way bearing on one side to form synchronous rotation and when the nut assembly generates a reverse motion trend, the one-way bearing is used to prevent the reverse motion trend from occurring.

2. The planetary roller screw self-locking structure according to claim 1, characterized in that: The one-way bearing includes an inner ring whose inner diameter surface is conically set. The nut assembly includes a nut and nut end covers arranged on both sides of the nut and fixed to the nuts respectively. The nut end cover is provided with a stop ring with a conical cross-section facing the one-way bearing opposite to it.

3. The planetary roller screw self-locking structure according to claim 2, characterized in that: A plurality of circumferentially distributed stopping grooves are provided on the outer surface of each stopping ring. The plurality of stopping grooves extend spirally on the outer surface of the stopping ring, and the spiral extension direction is opposite to the rotation direction allowed by the one-way bearing on that side.

4. The planetary roller screw self-locking structure according to claim 3, characterized in that: A stopping bead is provided in each of the stopping grooves, and the depth of the stopping groove gradually decreases in the rotation direction allowed by the one-way bearing on that side.

5. The planetary roller screw self-locking structure according to claim 2, characterized in that: A wave washer is provided between the one-way bearing and the nut end cover on each side.

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