Zero-position anti-rotation limiting mechanism and automobile brake-by-wire system

Abstract

The utility model relates to a zero-position anti-rotation limiting mechanism and an automobile brake-by-wire system, and belongs to the technical field of automobile brake-by-wire systems. The zero-position anti-rotation limiting mechanism comprises a lead screw shaft in transmission connection with a rotor shaft and a lead screw nut matched with the lead screw shaft, one end of the lead screw shaft is sleeved with a nut baffle in an anti-rotation mode, and the nut baffle is provided with a limiting boss I for limiting the lead screw nut located at the zero position to axially return. The problem that phases are difficult to match during installation can be solved, and the situation that parts are damaged or scrapped due to chippings generated by interference fit can be avoided.

Description

Technical Field

[0001] This utility model relates to the field of automotive brake-by-wire system technology, and in particular to a zero-position anti-rotation limit mechanism and an automotive brake-by-wire system. Background Technology

[0002] Currently, the main working principle of a brake-by-wire system is that the rotor shaft of the motor drives the lead screw shaft to rotate, and then the lead screw nut converts the rotational motion into linear motion, thereby driving the piston in the electric cylinder to move forward or backward. This compresses the brake fluid and builds up hydraulic pressure to provide braking force to the vehicle. During the pressure building and depressurization processes, the lead screw nut needs to perform reciprocating linear motion within a certain stroke. Without a zero-position anti-rotation limit structure, the lead screw nut will continue to retract during the depressurization process, coming into contact with other components and generating frictional torque. This frictional torque may exceed the starting torque of the motor, preventing the lead screw nut from moving forward further and causing the system to fail to achieve its braking function.

[0003] In existing technologies, a nut baffle is typically used, which is interference-fitted with the lead screw shaft. The nut baffle has a boss structure to convert axial impact into circumferential impact during retraction, thereby limiting the axial movement of the lead screw nut. The problem with zero-position anti-rotation limiting mechanisms using nut baffles is:

[0004] 1. The boss structure on the nut baffle is processed by welding or turning, which is time-consuming, labor-intensive, and costly. 2. When the screw nut retracts to near the zero position, if the circumferential position of the boss structure on the screw nut is used as a reference point, the relative angle between the boss structure on the nut baffle and the boss structure on the screw nut after the nut baffle is installed is denoted as β. In the zero-position anti-rotation limiting mechanism, the angle β on the boss on the screw nut baffle must be within a certain precision range during installation so that the two bosses can abut against each other and meet the strength requirements when the screw nut retracts to the zero position. However, during processing, the circumferential position of the boss on the screw nut is random, making it difficult to control the angle β and increasing installation difficulty. 3. When the screw nut baffle is interference-fitted with the screw shaft, if the phase does not meet the requirements, adjustment cannot be made, leading to part scrap. 4. There is a possibility of generating debris when the ball screw nut baffle is pressed into the ball screw shaft with an interference fit. These debris will fall into the ball screw assembly and reduce the service life of the ball screw assembly. Utility Model Content

[0005] To solve the above-mentioned technical problems, this utility model provides a zero-position anti-rotation limiting mechanism, which allows the phase of the nut baffle and the lead screw nut to be adjusted during installation. This solves the problem of phase mismatch during installation and avoids the situation where interference fit generates debris that could damage or scrap parts.

[0006] To achieve the above objectives, the technical solution adopted by this utility model to solve its technical problem is as follows: the zero-position anti-rotation limiting mechanism includes a lead screw shaft that is connected to the rotor shaft drive and a lead screw nut that cooperates with it. The lead screw nut is fixedly connected to the piston. A nut baffle is installed at one end of the lead screw shaft to prevent rotation. An elastic element and an external spline sleeve are fixedly sleeved at one end of the lead screw shaft. A limiting boss I is provided on the nut baffle to limit the axial retraction of the lead screw nut at the zero position.

[0007] The nut baffle includes a baffle body, and a flanged hole is provided at the center of the baffle body. The flanged hole is connected to the anti-rotation of the lead screw shaft, and the flanged hole is clearance-fitted with the lead screw shaft.

[0008] The cross-sectional shape of the flanged hole is consistent with the cross-sectional shape of the lead screw shoulder, and is composed of a combination of patterns arranged periodically around its center, including straight-edged polygons, curved-edged polygons, or mutually concave and convex structures; one end of the lead screw shaft mates with the flanged hole.

[0009] A limiting boss I is stamped on the side of the nut baffle facing the lead screw nut, and a limiting boss II is provided on the lead screw nut.

[0010] The lead screw shaft has a shoulder at one end, and the shoulder is connected to the nut baffle for axial blocking.

[0011] The distance between the center of the limiting boss I and the center of the limiting boss II is equal to the central axis of the lead screw shaft; when the lead screw nut is in the zero position, the limiting boss I is in limiting contact with the limiting boss II along the rotation direction of the lead screw shaft.

[0012] The transmission mechanism also includes an anti-rotation guide sleeve installed on the valve body of the online control braking system. Multiple guide ribs are provided on the inner wall of the anti-rotation guide sleeve along its length direction, and the lead screw nut is provided with a guide groove that is slidably connected to the corresponding guide rib.

[0013] One end of the lead screw shaft is interference-fitted with the outer spline sleeve, the outer spline sleeve is connected to the rotor shaft through the inner spline sleeve, and an elastic element is sleeved on the lead screw shaft between the outer spline sleeve and the nut baffle.

[0014] The elastic element is configured as an annular rubber elastic pad, and the flange of the nut baffle is connected to the anti-rotation feature of the elastic element.

[0015] The elastic element has a mounting hole at its center, which is connected to the lead screw shaft sleeve. The flange of the nut baffle extends into the mounting hole and is in anti-rotation clearance fit with the mounting hole.

[0016] A vehicle brake-by-wire system includes the aforementioned zero-position anti-rotation limit mechanism.

[0017] The beneficial effects of this utility model are:

[0018] 1. This utility model provides a zero-position anti-rotation limiting mechanism. By installing a nut baffle at one end of the lead screw shaft to prevent debris from falling into the transmission mechanism during the interference fit installation of the nut baffle and the lead screw shaft, which could damage the life of the transmission mechanism. At the same time, when installing the nut baffle, the phase between the nut baffle and the boss on the lead screw nut can be adjusted to avoid phase errors that may be caused by interference fit, which could lead to the scrapping of parts.

[0019] 2. In this utility model, the cross-sectional shape of the flanged hole on the nut baffle is formed by a combination of patterns arranged periodically around the center of the flanged hole. When installing the nut baffle, it can be adjusted at multiple angles to meet the phase requirements between the nut baffle and the boss on the lead screw nut. This allows the boss on the nut baffle to be machined at any position on the circumference without phase requirements, greatly reducing the difficulty of machining and installation. Attached Figure Description

[0020] The following is a brief explanation of the contents of each of the accompanying drawings and the markings in the drawings:

[0021] Figure 1 This is a schematic diagram of the phase angle between the lead screw nut and the boss on the nut baffle in the prior art;

[0022] Figure 2 This is a cross-sectional view of the zero-position anti-rotation limiting mechanism in this utility model;

[0023] Figure 3 This is an exploded view of the zero-position anti-rotation limiting mechanism in this utility model;

[0024] Figure 4 This is a structural schematic diagram of the relative position between the lead screw nut and the nut baffle when the screw is in the zero position in this utility model;

[0025] Figure 5 This is a schematic diagram of a structure in this utility model in which the flanged hole is connected to the lead screw shaft to prevent rotation.

[0026] Figure 6 This is a schematic diagram of another structure in this utility model where the flanged hole is connected to the lead screw shaft to prevent rotation.

[0027] The markings in the above figures are as follows: 1. Lead screw shaft, 11. Shoulder, 2. Lead screw nut, 21. Limiting boss II, 22. Guide groove, 3. Nut baffle, 31. Baffle body, 32. Flanged edge, 33. Flanged hole, 34. Limiting boss I, 4. Anti-rotation guide sleeve, 41. Guide rib, 5. External spline sleeve, 6. Elastic element, 61. Mounting hole. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate this utility model, but are not intended to limit the scope of this utility model.

[0029] In the description of this utility model, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0030] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0031] like Figures 1-4 As shown, this utility model provides a zero-position anti-rotation limiting mechanism, which is part of an automotive brake-by-wire system. It includes an anti-rotation guide sleeve 4 mounted on the valve body of the brake-by-wire system, a lead screw shaft 1 connected to the rotor shaft, and a corresponding lead screw nut 2. The rotor shaft is a hollow shaft, and the anti-rotation guide sleeve 4 is disposed within the inner cavity of the rotor shaft. Multiple guide ribs 41 are arranged along the length of the inner wall of the anti-rotation guide sleeve 4. The lead screw nut 2 is provided with guide grooves 22 that slide and guide the corresponding guide ribs 41. The lead screw nut 2 is fixedly connected to the piston. One end of the lead screw shaft 1 is interference-fitted with an outer spline sleeve 5, which is connected to the rotor shaft via an inner spline sleeve. The rotational motion of the rotor shaft is transmitted to the lead screw shaft 1 via spline transmission. The rotation of the lead screw shaft 1 drives the lead screw nut 2 to reciprocate stably along the axial direction of the lead screw shaft 1 and the axial direction of the anti-rotation guide sleeve 4, thereby driving the piston to move within the booster cylinder to achieve pressure build-up and pressure reduction.

[0032] The lead screw shaft 1, at the end furthest from the piston, is fitted with a nut baffle 3. The nut baffle 3 has a limiting boss I 34 that restricts the axial retraction of the lead screw nut 2 when it is in the zero position. The limiting boss I 34 is stamped from the side of the nut baffle 3 facing the lead screw nut 2, reducing processing steps and lowering costs. The lead screw nut 2 has a limiting boss II 21. The distance between the center of the limiting boss I 34 and the limiting boss II 21 and the central axis of the lead screw shaft 1 is equal. When the lead screw nut 2 is in the zero position, the limiting boss I 34 abuts against the limiting boss II 21 in the rotation direction of the lead screw shaft 1, preventing the lead screw nut 2 from retracting.

[0033] During the pressure building and depressurization process of the electric cylinder, the lead screw nut 2 needs to make reciprocating linear motion within a certain stroke. During the depressurization process, the lead screw nut 2 will keep retracting. When the lead screw nut 2 retracts to the zero position, the limiting boss I 34 makes a limiting contact with the limiting boss II 21 along the rotation direction of the lead screw shaft 1, converting the axial force of the lead screw shaft 1 into the frictional torque between the limiting bosses, so that the lead screw nut 2 no longer retracts.

[0034] Therefore, by installing a nut baffle 3 at one end of the lead screw shaft 1 to prevent rotation, this utility model not only allows the nut baffle 3 to rotate synchronously with the lead screw shaft 1, but also avoids the situation where debris may fall into the transmission mechanism during the interference fit installation of the nut baffle 3 and the lead screw shaft 1, which could damage the life of the transmission mechanism. At the same time, when installing the nut baffle 3, the phase between the zero position limit boss I 34 and the limit boss II 21 can be adjusted, avoiding the situation where the interference fit may cause phase errors that could lead to the scrapping of parts.

[0035] Specifically, the nut baffle 3 includes a baffle body 31, with a through hole at the center of the baffle body 31. The through hole is flanged outward 32 to form a flanged hole 33. The flanged hole 33 is connected to the lead screw shaft 1 to prevent rotation, and the flanged hole 33 is clearance-fitted with the lead screw shaft 1. This avoids the situation where debris may fall into the transmission mechanism during the installation of the nut baffle 3 and the lead screw shaft 1 with an interference fit, which could damage the life of the transmission mechanism. It also avoids the situation where the interference fit may cause phase errors and result in the scrapping of parts.

[0036] The cross-sectional shape of the flanged hole 33 is consistent with that of the lead screw shaft 1, and is composed of a combination of patterns arranged periodically around the center of the flanged hole 33, including straight-edged polygons, curved-edged polygons, or mutually concave and convex structures, such as... Figure 5 and Figure 6As shown. The cross-sectional shape of one end of the lead screw shaft 1 matches the cross-sectional shape of the flanged hole 33, allowing for multi-angle adjustment when installing the nut baffle 3. This satisfies the phase accuracy requirements between the nut baffle 3 and the boss on the lead screw nut 2, enabling the boss on the nut baffle 3 to be machined at any position on the circumference without phase requirements, greatly reducing machining and installation difficulties.

[0037] In addition, in order to axially limit the lead screw shaft 1, a shoulder 11 is provided at one end of the lead screw shaft 1. The shoulder 11 stops on one side of the nut baffle 3. An elastic element 6 is sleeved on the lead screw shaft 1 between the outer spline sleeve 5 and the nut baffle 3. The elastic element 6 stops on the other side of the nut baffle 3, thereby realizing the axial limitation of the nut baffle 3.

[0038] The elastic element 6 is set as an annular rubber elastic pad, which can not only limit the axial movement of the nut baffle 3, but also eliminate the axial installation clearance of the lead screw shaft.

[0039] The flange 32 of the nut baffle 3 extends into the elastic element 6 and is connected to the anti-rotation mechanism of the elastic element 6. Specifically, the elastic element 6 has a mounting hole 61 at its center. The cross-sectional shape of the mounting hole 61 is polygonal or irregular. The mounting hole 61 is sleeved and connected to the lead screw shaft 1. The flange 32 of the nut baffle 3 extends into the mounting hole 61 and is clearance-fitted with the anti-rotation mechanism of the mounting hole 61. This ensures that the lead screw shaft 1 rotates synchronously with the outer spline sleeve 5, the nut baffle 3, and the elastic element 6, without causing abnormal noise or wear of parts due to relative rotation, thus improving the service life of the entire transmission mechanism.

[0040] The working principle of the aforementioned zero-position anti-rotation limiting mechanism is as follows: When braking and pressure building are required, the rotor shaft of the motor rotates, and the rotational motion of the rotor shaft is transmitted to the lead screw shaft 1 through spline transmission. The rotation of the lead screw shaft 1 drives the lead screw nut 2 on it to move stably along the axial direction of the anti-rotation guide sleeve 4 away from the nut baffle 3 by a specific stroke, thereby driving the piston to move in the booster cylinder to achieve pressure building. When braking and pressure reduction are required, the rotor shaft of the motor rotates in the opposite direction, and the rotational motion of the rotor shaft is transmitted to the lead screw shaft 1 through spline transmission. The rotation of the lead screw shaft 1 drives the lead screw nut 2 on it to move stably along the axial direction of the anti-rotation guide sleeve 4 towards the nut baffle 3, thereby driving the piston to move in the booster cylinder. When the lead screw nut 2 returns to the zero position, the limiting boss I 34 and the limiting boss II 21 in the rotation direction of the lead screw shaft 1 are in contact, converting the axial force of the lead screw shaft 1 into a frictional torque between the limiting bosses, so that the lead screw nut 2 no longer returns.

[0041] In summary, this utility model allows the phase of the nut baffle and the lead screw nut to be adjusted during installation, which solves the problem of phase mismatch during installation and avoids the situation where interference fit generates debris that could damage or scrap parts.

[0042] The above description is merely an illustration of some principles of this utility model. This specification is not intended to limit this utility model to the specific structure and applicable scope shown. Therefore, all possible modifications and equivalents that may be used fall within the scope of the patent application of this utility model.

Claims

1. A zero-position anti-rotation limiting mechanism, comprising a lead screw shaft drivenly connected to a rotor shaft and a lead screw nut cooperating therewith, wherein the lead screw nut is fixedly connected to a piston, characterized in that, One end of the lead screw shaft is fitted with a nut baffle to prevent rotation. The nut baffle is provided with a limiting boss I to restrict the axial retraction of the lead screw nut when it is in the zero position.

2. The zero-position anti-rotation limiting mechanism according to claim 1, characterized in that: The nut baffle includes a baffle body, and a flanged hole is provided at the center of the baffle body. The flanged hole is connected to the anti-rotation of the lead screw shaft, and the flanged hole is clearance-fitted with the lead screw shaft.

3. The zero-position anti-rotation limiting mechanism according to claim 2, characterized in that: The cross-sectional shape of the flanged hole and the cross-sectional shape of the lead screw shaft shoulder are composed of a combination of patterns arranged periodically around their center. The patterns include straight-edged polygons, curved-edged polygons, or mutually concave and convex structures. One end of the lead screw shaft is anti-rotationally engaged with the flanged hole.

4. The zero-position anti-rotation limiting mechanism according to claim 1, characterized in that: A limiting boss I is stamped on the side of the nut baffle facing the lead screw nut, and a limiting boss II is provided on the lead screw nut.

5. The zero-position anti-rotation limiting mechanism according to claim 4, characterized in that: The lead screw shaft has a shoulder at one end, and the shoulder is connected to the nut baffle for axial blocking. The distance between the center of the limiting boss I and the center of the limiting boss II is equal to the central axis of the lead screw shaft; when the lead screw nut is in the zero position, the limiting boss I is in limiting contact with the limiting boss II along the rotation direction of the lead screw shaft.

6. The zero-position anti-rotation limiting mechanism according to claim 1, characterized in that: The zero-position anti-rotation limiting mechanism also includes an anti-rotation guide sleeve installed on the valve body of the online control braking system. Multiple guide ribs are provided on the inner wall of the anti-rotation guide sleeve along its length direction, and the lead screw nut is provided with a guide groove that is slidably connected to the corresponding guide rib.

7. The zero-position anti-rotation limiting mechanism according to claim 2, characterized in that: One end of the lead screw shaft is interference-fitted with the outer spline sleeve, the outer spline sleeve is connected to the rotor shaft through the inner spline sleeve, and an elastic element is sleeved on the lead screw shaft between the outer spline sleeve and the nut baffle.

8. The zero-position anti-rotation limiting mechanism according to claim 7, characterized in that: The elastic element is configured as an annular rubber elastic pad, and the flange of the nut baffle is connected to the anti-rotation feature of the elastic element.

9. The zero-position anti-rotation limiting mechanism according to claim 8, characterized in that: The elastic element has a mounting hole at its center, which is connected to the lead screw shaft sleeve. The flange of the nut baffle extends into the mounting hole and is in anti-rotation clearance fit with the mounting hole.

10. A brake-by-wire system for automobiles, characterized in that, Includes the zero-position anti-rotation limiting mechanism as described in any one of claims 1-9.

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