Self-locking mechanism of rear wheel steering system and rear wheel steering system

Abstract

The utility model relates to the technical field of rear wheel steering, and provides a self-locking mechanism of a rear wheel steering system and the rear wheel steering system. The self-locking mechanism of the rear wheel steering system is assembled between an input shaft and an output shaft of a power-assisted motor of the rear wheel steering system, and comprises a fixed check ring, a locking mechanism and a locking mechanism, a body of the anti-rotating pin is mounted in the first channel of the output shaft through a pre-tightening piece, and a support arm of the anti-rotating pin extends into the second channel of the input shaft; in the self-locking state, the anti-rotating pin abuts against the check ring under the action of the pre-tightening piece, and a torque transmission path from the output shaft to the input shaft is cut off. When the input shaft rotates, the anti-rotation pin leaves the check ring under the action of the second channel, and a torque transmission path from the input shaft to the output shaft is conducted. According to the self-locking mechanism, the anti-rotating pin, the pre-tightening piece, the check ring and the channels formed in the end faces of the input shaft and the output shaft are matched, so that the rear wheels are prevented from steering when a rear wheel steering system is not activated, and the rear wheels are helped to steer when the rear wheel steering system is activated.

Description

Technical Field

[0001] The utility model relates to the technical field of rear wheel steering, in particular to a self-locking mechanism of a rear wheel steering system and a rear wheel steering system. Background Art

[0002] Rear Wheel Steering (RWS) can improve the vehicle's handling and safety performance and facilitate the vehicle's steering operation.

[0003] In most vehicles equipped with rear-wheel steering systems, the front-wheel steering system is still the main actuator for vehicle direction control, and the rear-wheel steering system is only activated when needed. When the rear-wheel steering system is not activated (including in failure mode, etc.), it is necessary to avoid accidental steering of the rear wheels.

[0004] Therefore, how to prevent the rear wheel from steering when the rear wheel steering system is not activated, and allow the rear wheel to steering when the rear wheel steering system is activated, is a problem that needs to be solved urgently in the rear wheel steering system.

[0005] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute prior art known to ordinary technicians in the field. Utility Model Content

[0006] In view of this, the utility model provides a self-locking mechanism of a rear-wheel steering system and a rear-wheel steering system, which can prevent the rear wheels from steering when the rear-wheel steering system is not activated, and help the rear wheels to steer when the rear-wheel steering system is activated.

[0007] One aspect of the utility model provides a self-locking mechanism of a rear-wheel steering system, which is assembled between the input shaft and the output shaft of the power-assisting motor of the rear-wheel steering system, and includes: a fixed stop ring; an anti-rotation pin, wherein the body of the anti-rotation pin is installed in the first groove of the output shaft through a preload, and the support arm of the anti-rotation pin extends into the second groove of the input shaft; in the self-locking state, the anti-rotation pin abuts against the stop ring under the action of the preload, and the torque transmission path from the output shaft to the input shaft is cut off; when the input shaft rotates, the anti-rotation pin leaves the stop ring under the action of the second groove, and the torque transmission path from the input shaft to the output shaft is connected.

[0008] In some embodiments, the end surface of the body of the anti-rotation pin and the inner wall of the stop ring are provided with matching tooth structures; in the self-locking state, the tooth structures are engaged; when the input shaft rotates, the tooth structures are separated.

[0009] In some embodiments, the second groove includes two connected arc grooves, the two arc grooves are symmetrically distributed about the radial direction of the input shaft, and the arc groove is eccentric relative to the input shaft; when the support arm is located at the connecting part of the two arc grooves, the self-locking mechanism is in the self-locking state; when the support arm is located in any arc groove, the self-locking mechanism is unlocked.

[0010] In some embodiments, the first groove extends in a radial direction of the output shaft.

[0011] In some embodiments, the preload member is a spring pre-compressed between the first channel and the body of the anti-rotation pin.

[0012] In some embodiments, the anti-rotation pins include a plurality of pins that are evenly distributed along the circumferential direction.

[0013] In some embodiments, the retaining ring is fixed to a housing of the power-assisted motor or a housing of a rack of the rear-wheel steering system.

[0014] In some embodiments, the end surface of the output shaft is provided with a protrusion, the end surface of the input shaft is provided with a mounting hole, and the protrusion and the mounting hole are mounted by means of a bushing.

[0015] In some embodiments, the output shaft is rotatably supported by bearings.

[0016] Another aspect of the utility model provides a rear-wheel steering system, comprising: a power-assisting motor; a self-locking mechanism as described in any of the above embodiments, wherein the self-locking mechanism is assembled between the input shaft and the output shaft of the power-assisting motor; wherein the output shaft is connected to a rack through a reduction mechanism, and both ends of the rack are connected to two rear wheels.

[0017] Compared with the prior art, the beneficial effects of the present invention include at least:

[0018] The self-locking mechanism of the utility model prevents the rear wheels from turning when the rear wheel steering system is not activated, and helps the rear wheels to turn when the rear wheel steering system is activated, through the cooperation of the anti-rotation pin, the preload member, the stop ring and the grooves arranged on the end faces of the input shaft and the output shaft.

[0019] Specifically, the body of the anti-rotation pin is installed in the first groove of the output shaft through a preload. When the input shaft does not output torque (the power-assisted motor is not working at this time, so the rear-wheel steering system is not activated), the anti-rotation pin abuts against the stop ring under the action of the preload, so that the self-locking mechanism is in a self-locking state to cut off the torque transmission path from the output shaft to the input shaft; in this way, the power-assisted motor will not rotate, thereby preventing the rear wheels from turning and keeping the rear wheels running in a straight line;

[0020] When the input shaft rotates (indicating that the power-assisted motor is in an autonomously rotating working state at this time, and the rear-wheel steering system is activated), the second groove pulls the arm of the anti-rotation pin, so that the anti-rotation pin leaves the stop ring. At this time, the self-locking mechanism is unlocked, and the torque transmission path from the input shaft to the output shaft is connected, so that the torque from the power-assisted motor can be smoothly transmitted through the input shaft and the output shaft to help the rear wheel steering;

[0021] When the input shaft stops rotating (i.e. the power-assisting motor no longer outputs torque), the preload member will push the anti-rotation pin to abut against the stop ring, thereby achieving self-locking.

[0022] It should be understood that the above general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings herein are incorporated into the specification and constitute a part of the specification, showing embodiments consistent with the present utility model, and together with the specification, are used to explain the principles of the present utility model. Obviously, the drawings described below are only some embodiments of the present utility model, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 A schematic diagram showing the structure of a rear wheel steering system in an embodiment of the utility model is shown;

[0025] Figure 2 A cross-sectional structural diagram of the self-locking mechanism in an embodiment of the utility model is shown;

[0026] Figure 3 A schematic diagram of the explosion structure of the self-locking mechanism in the embodiment of the utility model is shown;

[0027] Figure 4 A schematic diagram showing the engagement of the anti-rotation pin and the toothed structure of the stop ring in an embodiment of the utility model;

[0028] Figure 5 A schematic diagram showing the separation of the anti-rotation pin and the toothed structure of the stop ring in the embodiment of the utility model;

[0029] Figure 6 A schematic diagram showing that the anti-rotation pin and the toothed structure of the stop ring are not engaged when the input shaft stops rotating in the embodiment of the utility model. DETAILED DESCRIPTION

[0030] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the embodiments set forth herein. Instead, these embodiments are provided so that the present invention will be comprehensive and complete and fully convey the concepts of the example embodiments to those skilled in the art. The same reference numerals in the figures represent the same or similar structures, and thus their repeated description will be omitted.

[0031] The words "first", "second" and similar words used in the specific description do not indicate any order, quantity or importance, but are only used to distinguish different components. The orientation or positional relationship indicated by the terms "upper" and "lower" etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, it cannot be understood as a limitation on the present utility model. The term "plurality" means two or more, unless otherwise clearly and specifically defined. In addition, in the description of the present utility model, when it is said that a device is "connected" to another device, this includes not only the case of direct connection, but also the case of indirect connection through other elements.

[0032] It should be noted that, in the absence of conflict, the embodiments of the present utility model and features in different embodiments may be combined with each other.

[0033] Figure 1 The structure of the rear wheel steering system in the embodiment of the utility model is schematically shown. Figure 2 The cross-sectional structure of the self-locking mechanism in the embodiment of the utility model is shown. Figure 3 The explosion structure of the self-locking mechanism in the embodiment of the utility model is shown; Figures 1 to 3 As shown, the self-locking mechanism 100 of the rear-wheel steering system provided by the embodiment of the utility model is assembled between the input shaft 210 and the output shaft 220 of the power-assisted motor 200 of the rear-wheel steering system, and includes:

[0034] A fixed stop ring 110;

[0035] The anti-rotation pin 120, the body 120a of the anti-rotation pin 120 is installed in the first groove 221 of the output shaft 220 through the pre-tightening member 130, and the arm 120b of the anti-rotation pin 120 extends into the second groove 212 of the input shaft 210;

[0036] In the self-locking state, the anti-rotation pin 120 abuts against the stop ring 110 under the action of the preload member 130 , and the torque transmission path from the output shaft 220 to the input shaft 210 is cut off;

[0037] When the input shaft 210 rotates, the anti-rotation pin 120 leaves the stop ring 110 under the action of the second groove 212 , and the torque transmission path from the input shaft 210 to the output shaft 220 is connected.

[0038] The above-mentioned self-locking mechanism 100, through the cooperation of the anti-rotation pin 120, the preload member 130, the stop ring 110 and the grooves arranged on the end faces of the input shaft 210 and the output shaft 220, prevents the rear wheels from turning when the rear-wheel steering system is not activated, and helps the rear wheels to turn when the rear-wheel steering system is activated.

[0039] Specifically, the body 120a of the anti-rotation pin 120 is installed in the first groove 221 of the output shaft 220 through the preload 130. When the input shaft 210 does not output torque (the power-assisted motor 200 is not working at this time, so the rear-wheel steering system is not activated), the anti-rotation pin 120 abuts against the stop ring 110 under the action of the preload 130, so that the self-locking mechanism 100 is in a self-locking state, so as to cut off the torque transmission path from the output shaft 220 to the input shaft 210; in this way, the power-assisted motor 200 will not rotate, thereby preventing the rear wheels from turning and keeping the rear wheels running in a straight line;

[0040] When the input shaft 210 rotates (indicating that the power-assisting motor 200 is in an autonomously rotating working state at this time, and the rear-wheel steering system is activated), the second groove 212 pulls the arm 120b of the anti-rotation pin 120, so that the anti-rotation pin 120 leaves the stop ring 110. At this time, the self-locking mechanism 100 is unlocked, and the torque transmission path from the input shaft 210 to the output shaft 220 is connected, so that the torque from the power-assisting motor 200 can be smoothly transmitted through the input shaft 210 and the output shaft 220, thereby helping the rear-wheel steering;

[0041] When the input shaft 210 stops rotating (ie, the power-assisting motor 200 no longer outputs torque), the preload member 130 will push the anti-rotation pin 120 to abut against the stop ring 110, thereby achieving self-locking.

[0042] Among them, the connection between the input shaft 210 and the output shaft 220 of the power-assisted motor 200 has a reasonable margin / idle stroke to ensure that when the input shaft 210 rotates, the anti-rotation pin 120 can be pulled away from the stop ring 110 through the second groove 212, and then the output shaft 220 can be driven to rotate; and, when the input shaft 210 stops rotating and the self-locking mechanism 100 has not entered the self-locking state, the self-locking mechanism 100 can be put into the self-locking state by rotating the output shaft 220 without affecting the input shaft 210.

[0043] Figure 4 The structure of the anti-rotation pin and the toothed structure of the stop ring in the embodiment of the utility model is shown in FIG. Figure 5 The structure in which the anti-rotation pin and the toothed structure of the stop ring are separated in the embodiment of the utility model is shown; Figures 1 to 5As shown, in some embodiments, the end surface of the body 120a of the anti-rotation pin 120 and the inner wall of the stop ring 110 are provided with matching tooth structures 150; in the self-locking state, the tooth structures 150 are engaged; when the input shaft 210 rotates, the tooth structures 150 are separated.

[0044] The engagement of the toothed structure 150 keeps the anti-rotation pin 120 and the stop ring 110 fixed, thereby keeping the output shaft 220 fixed, preventing the torque applied to the output shaft 220 in the self-locking state from being transmitted to the input shaft 210. When the input shaft 210 rotates, the toothed structure 150 is separated to allow the torque to be transmitted between the input shaft 210 and the output shaft 220.

[0045] The number of teeth, tooth width and other parameters of the toothed structure 150 can be adjusted as needed to ensure that the anti-rotation pin 120 and the stop ring 110 remain stable in the self-locking state; and to ensure that when the input shaft 210 stops rotating and the self-locking mechanism 100 does not enter the self-locking state, the output shaft 220 rotates and adjusts from the separated state to the engaged state, so that the self-locking mechanism 100 is locked.

[0046] Figure 6 The structure in which the anti-rotation pin and the toothed structure of the stop ring do not engage when the input shaft stops rotating in the embodiment of the utility model is illustrated. Figures 4 to 6 , and refer to Figures 1 to 3 As shown:

[0047] When the input shaft 210 stops rotating, the ideal situation is as follows Figure 4 As shown, the anti-rotation pin 120 is engaged with the tooth structure 150 of the stop ring 110 , so that the self-locking mechanism 100 enters a self-locking state.

[0048] Worst case reference Figure 6 As shown, the anti-rotation pin 120 is aligned exactly with the toothed structure 150 of the stop ring 110. At this time, the output shaft 220 needs to be controlled to rotate a certain angle to make the toothed structure 150 engage. In different designs, the rotation angle of the output shaft 220 required to switch the toothed structure 150 from being aligned to being engaged may be different; specifically, the required rotation angle of the output shaft 220 is determined according to the number of teeth of the toothed structure 150, and the number of teeth is determined according to the accuracy of the rear wheel steering system (i.e., the rack stroke). In this embodiment, according to the test, in the worst case, the output shaft 220 needs to rotate 1.8° to make the toothed structure 150 engage. According to the relationship between the rack stroke and the output shaft rotation angle:

[0049]

[0050] The rack travel refers to the travel / displacement of the rack 240 of the rear wheel steering system. The output shaft rotation angle is the rotation angle of the output shaft 220. In this embodiment, the output shaft rotation angle is 1.8°. The output shaft 220 is connected to the reduction mechanism. The ratio of the number of teeth of the driving wheel to the number of teeth of the driven wheel is determined according to the configuration of the reduction mechanism. In this embodiment, for example, The rack 240 is configured as a screw structure, on which a nut is disposed to form a lead screw nut structure, and the reduction mechanism is connected to the nut. The lead of the lead screw nut is determined according to the vehicle design requirements, and in this embodiment, for example, it is 8 mm. Then, in this embodiment, the calculated rack stroke is approximately 0.0097 mm. That is, when the output shaft 220 rotates 1.8° to engage the toothed structure 150, the rack 240 only moves 0.0097 mm, which meets the requirements of the rear wheel steering system and its self-locking performance.

[0051] In the specific design process, from the time when the input shaft 210 stops rotating to the time when the self-locking mechanism 100 enters the self-locking state, it is sufficient that the displacement of the rack 240 caused by the rotation angle of the output shaft 220 required to move the toothed structure 150 from the disengaged state to the engaged state is within the rack displacement range allowed by the rear-wheel steering system.

[0052] For other situations, please refer to Figure 5 As shown, there is a certain deviation between the anti-rotation pin 120 and the tooth structure 150 of the stop ring 110, and the output shaft 220 needs to be controlled to rotate a certain angle to make the tooth structure 150 engage. The specific adjustment process can refer to the description of the above embodiment.

[0053] In addition, during the design of the toothed structure 150 , it is also necessary to ensure that in the self-locking state, when the force from the rack 240 is output to the output shaft 220 , the toothed structure 150 can withstand the pressure to prevent the anti-rotation pin 120 from separating from the stop ring 110 .

[0054] Specifically, according to the vehicle design requirements, under normal circumstances, the force from the rack 240 when the vehicle is driving is 14.5KN. According to the relationship between the output shaft torque and the rack force:

[0055]

[0056] In this embodiment, the rack force is 14.5KN, and the ratio of the number of teeth on the driven wheel to the number of teeth on the driving wheel is The lead of the lead screw nut is 8mm; then, the calculated output shaft torque is 4.47Nm. Further, through software simulation, it can be known that when the output shaft torque is 4.47Nm, the pressure borne by the toothed structure 150 is 236MPa, which is less than its ultimate bearing pressure of 600MPa (the toothed structure 150 is made of steel material, for example, and its ultimate bearing pressure is about 600MPa after testing).

[0057] Therefore, the toothed structure 150 of the present invention can maintain stability in a self-locking state.

[0058] Continue to combine Figures 1 to 6 As shown, in some embodiments, the second groove 212 includes two connected arc grooves 212', the two arc grooves 212' are symmetrically distributed about the radial direction R of the input shaft 210, and the arc groove 212' is eccentric relative to the input shaft 210;

[0059] When the support arm 120b is located at the connecting portion of the two arc-shaped grooves 212' (such as Figure 4 The self-locking mechanism 100 is in the self-locking state;

[0060] When the support arm 120b is located in any arc-shaped groove 212' (such as Figure 5 / Figure 6 The self-locking mechanism 100 is unlocked.

[0061] By designing the arc groove 212' to be eccentric with respect to the input shaft 210, that is, the extension direction of the arc groove 212' is biased toward the center of the circle of the input shaft 210, the anti-rotation pin 120 can be "pulled away" from the stop ring 110 through the arc groove 212' when the input shaft 210 rotates, so that the self-locking mechanism 100 is unlocked. By designing the two arc grooves 212' to be symmetrically distributed about the radial direction R of the input shaft 210, the self-locking mechanism 100 can be unlocked when the input shaft 210 rotates forward or reversely; and when the support arm 120b is located at the connecting portion of the two arc grooves 212', the anti-rotation pin 120 engages with the toothed structure 150 of the stop ring 110, so that the self-locking mechanism 100 is locked.

[0062] In other embodiments, the second groove 212 may also have other designs, as long as the anti-rotation pin 120 can abut against the stop ring 110 in the self-locking state and the anti-rotation pin 120 can leave the stop ring 110 when the input shaft 210 rotates.

[0063] In some embodiments, the first groove 221 extends along the radial direction of the output shaft 220 , so as to facilitate the engagement of the toothed structure 150 .

[0064] In some embodiments, the pre-tightening member 130 is a spring pre-compressed between the first groove 221 and the body 120a of the anti-rotation pin 120. Alternatively, the pre-tightening member 130 may also be other suitable structures, as long as it can provide a pre-tightening force, drive the self-locking mechanism 100 to lock when the booster motor 200 is not working, and allow the anti-rotation pin 120 to leave the stop ring 110 when the input shaft 210 rotates.

[0065] In some embodiments, the anti-rotation pins 120 include a plurality of pins evenly spaced and distributed along the circumferential direction, so that the anti-rotation pins 120 and the stop ring 110 can be evenly and stably matched in the circumferential direction, which is conducive to achieving the self-locking state of the self-locking mechanism 100 .

[0066] In the case that the anti-rotation pin 120 includes a plurality of them, correspondingly, the pre-tightening member 130 , the first groove 221 , and the second groove 212 are all provided in plurality. Figure 3 In the figure, it is shown that the anti-rotation pin 120, the pre-tightening member 130, the first groove 221, and the second groove 212 are all provided in four, but the present invention is not limited thereto.

[0067] In some embodiments, the stop ring 110 is fixed to the housing of the power assist motor 200, and the stop ring 110 can also be fixed to the housing of the rack 240, which can be determined according to design requirements. Figure 1 In the illustrated embodiment, the stop ring 110 is fixed to the housing of the rack 240; specifically, the stop ring 110 and the housing of the rack 240 may be fixed by interference fit, threaded connection, or the like.

[0068] In some embodiments, the end surface of the output shaft 220 is provided with a protrusion 220', the end surface of the input shaft 210 is provided with a mounting hole 210', and the protrusion 220' and the mounting hole 210' are mounted with a bushing 230. In this way, the connection between the input shaft 210 and the output shaft 220 is achieved.

[0069] In some embodiments, the output shaft 220 is rotatably supported by a bearing 260 .

[0070] The embodiment of the utility model also provides a rear-wheel steering system, including: a power-assisting motor 200; a self-locking mechanism 100, which is assembled between the input shaft 210 and the output shaft 220 of the power-assisting motor 200; wherein the output shaft 220 is connected to the rack 240 through a reduction mechanism, and the two ends of the rack 240 are connected to the two rear wheels.

[0071] The rear-wheel steering system of the present invention, by configuring the above-mentioned self-locking mechanism 100, can prevent the rear wheels from steering when the rear-wheel steering system is not activated through the cooperation of the anti-rotation pin 120, the preload member 130, the stop ring 110 and the grooves arranged on the end faces of the input shaft 210 and the output shaft 220, and help the rear wheels to steer when the rear-wheel steering system is activated.

[0072] The above contents are further detailed descriptions of the present invention in combination with specific preferred implementations, and the specific implementation of the present invention cannot be considered to be limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A self-locking mechanism of a rear wheel steering system, characterized in that: Assembled between the input shaft and the output shaft of the power-assisted motor of the rear-wheel steering system, comprising: Fixed stop ring; An anti-rotation pin, wherein the body of the anti-rotation pin is installed in the first groove of the output shaft through a pre-tightening member, and the support arm of the anti-rotation pin extends into the second groove of the input shaft; In the self-locking state, the anti-rotation pin abuts against the stop ring under the action of the preload member, and the torque transmission path from the output shaft to the input shaft is cut off; When the input shaft rotates, the anti-rotation pin leaves the stop ring under the action of the second groove, and the torque transmission path from the input shaft to the output shaft is opened.

2. The self-locking mechanism according to claim 1, characterized in that: The end surface of the body of the anti-rotation pin and the inner wall of the stop ring are provided with matching tooth structures; In the self-locking state, the toothed structure is engaged; When the input shaft rotates, the teeth disengage.

3. The self-locking mechanism according to claim 1, characterized in that: The second groove includes two sections of connected arc grooves, the two sections of the arc grooves are symmetrically distributed with respect to the radial direction of the input shaft, and the arc grooves are eccentric with respect to the input shaft; When the support arm is located at the connecting portion of the two arc-shaped grooves, the self-locking mechanism is in the self-locking state; When the support arm is located in any section of the arc-shaped groove, the self-locking mechanism is unlocked.

4. The self-locking mechanism according to claim 1, characterized in that: The first groove extends in a radial direction of the output shaft.

5. The self-locking mechanism according to claim 1, characterized in that: The preload element is a spring pre-compressed between the first groove and the body of the anti-rotation pin.

6. The self-locking mechanism according to any one of claims 1 to 5, characterized in that: The anti-rotation pins include a plurality of pins that are evenly distributed along the circumferential direction.

7. The self-locking mechanism according to claim 1, characterized in that: The retaining ring is fixed to a housing of the power-assisted motor or a housing of a rack of the rear-wheel steering system.

8. The self-locking mechanism according to claim 1, characterized in that: The end surface of the output shaft is provided with a protrusion, and the end surface of the input shaft is provided with a mounting hole. The protrusion and the mounting hole are mounted in cooperation with each other through a bushing.

9. The self-locking mechanism according to claim 1, characterized in that: The output shaft is rotatably supported by a bearing.

10. A rear wheel steering system, characterized in that: include: Power assist motor; The self-locking mechanism according to any one of claims 1 to 9, wherein the self-locking mechanism is mounted between the input shaft and the output shaft of the booster motor; Wherein, the output shaft is connected to the rack through a speed reduction mechanism, and the two ends of the rack are connected to the two rear wheels.

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