Ball screw pair

Abstract

The utility model provides a kind of ball screw pair, including screw shaft, nut, gear and bearing;The screw shaft is integrated structure, and gear section, bearing section and thread raceway section are integrated in sequence in its axial direction;Gear section is equipped with gear and directly engaged with driving motor gear transmission, bearing section is equipped with bearing, and thread raceway section is threadedly connected with nut.Integrated screw shaft structure is utilized, gear section, bearing section and thread raceway section are integrated in sequence in the axial direction, gear transmission, bearing support and ball screw conversion three major functional units are compressed to single axle body space.The design completely abandons traditional split type layout, directly eliminates idler / planetary gear train intermediate transmission link, significantly shortens transmission chain;While realizing gear-motor direct engagement, bearing accurate positioning, substantially reduce axial installation space and component quantity, perfect adaptation wheel edge brake assembly size constraint.

Description

Technical Field

[0001] This utility model relates to the field of ball screw pair technology, and specifically to a ball screw pair. Background Technology

[0002] In automotive electromechanical braking systems, the ball screw pair, as the core transmission component for converting rotary motion into linear motion, directly restricts the miniaturization and weight reduction of the braking assembly due to its spatial layout and structural complexity. Traditional solutions require assembling the drive gear, support bearing, and ball screw as separate components, resulting in a long transmission chain and large space occupation, especially difficult to arrange efficiently in the narrow space around the wheel. At the same time, the split design increases assembly steps and accumulated errors, reduces system rigidity and transmission efficiency, and cannot meet the stringent requirements of braking systems for high integration and high reliability. Summary of the Invention

[0003] This utility model proposes a ball screw pair that solves the problems of long transmission chains and low space utilization caused by the separate layout of gears, bearings and screws in the existing ball screw pair.

[0004] The technical solution of this utility model is implemented as follows:

[0005] A ball screw assembly includes a screw shaft, a screw nut, a gear, and a bearing. The screw shaft is an integral structure, with a gear section, a bearing section, and a threaded raceway section sequentially integrated along its axial direction. The gear section has a gear that directly meshes with the gear of a drive motor. The bearing section has a bearing, and the threaded raceway section is threadedly connected to the screw nut. By integrating the gear, bearing, and screw nut through the screw shaft, the functions of gear transmission, bearing support, and ball screw transmission are achieved.

[0006] Furthermore, a sleeve is fitted around the outside of the nut, covering at least a portion of the outer periphery of the nut to form a semi-sealed structure, thereby blocking the reverser mounting hole on the nut to prevent lubricating grease leakage.

[0007] Furthermore, the wire nut is provided with a plurality of reverser mounting holes, and a reverser is installed in the reverser mounting holes;

[0008] The reverser, the screw nut, and the thread raceway section all have built-in ball return channels, in which rolling balls are connected, and the balls form a closed loop path between the screw shaft and the ball return channel of the screw nut.

[0009] Furthermore, an anti-rotation fit structure is provided between the nut and the sleeve to constrain the nut to move only along the axial direction.

[0010] Furthermore, the anti-rotation mating structure includes a non-cylindrical mating part located at the end of the nut, and a corresponding mating part located inside the sleeve to adapt to the non-cylindrical mating part.

[0011] Furthermore, the end of the sleeve is provided with an external connection structure for adapting and connecting with an external braking assembly.

[0012] Furthermore, the outer wall of the sleeve is provided with an accessory mounting structure for installing a dust cover.

[0013] Furthermore, it also includes an axial limiting structure, which includes a stop pin press-fitted on the lead screw shaft and a stop block located at the end of the lead screw nut; the stop pin and the stop block cooperate to limit the end position of the axial travel of the lead screw nut relative to the lead screw shaft and prevent return impact.

[0014] Furthermore, the bearing section is configured to provide an axial positioning surface for the inner ring of the bearing.

[0015] Furthermore, the gear is either a spur gear or a helical gear, and its tooth profile parameters are matched with those of the drive motor gear to achieve direct meshing transmission.

[0016] The beneficial effects of the technical solution provided in this application are as follows:

[0017] 1. This ball screw assembly utilizes an integrated screw shaft structure, axially integrating the gear section, bearing section, and threaded raceway section to compress the three major functional units of gear transmission, bearing support, and ball screw conversion into a single shaft space. This design completely abandons the traditional split layout, directly eliminating intermediate transmission links such as idler gears / planetary gear trains, significantly shortening the transmission chain; while achieving direct gear-motor meshing and precise bearing positioning, it greatly reduces axial installation space and the number of components, perfectly adapting to the size constraints of the wheel-side brake assembly, and providing the system with higher rigidity and response speed, fundamentally solving the core pain points of "limited space and cumbersome assembly" in existing technologies.

[0018] 2. This ball screw assembly, with its highly integrated design, not only achieves the goal of lightweighting and reduces material and manufacturing costs, but also reduces power transmission losses and improves energy conversion efficiency due to the simplification of the transmission chain. In addition, the structural stability of the integrated screw shaft can effectively suppress vibration and noise caused by the assembly of multiple parts, extend the life of key components, and meet the stringent requirements of automotive braking systems for high durability and low failure rate. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1This is a three-dimensional schematic diagram of the ball screw pair of this utility model;

[0021] Figure 2 This is a cross-sectional schematic diagram of the ball screw assembly of this utility model;

[0022] Figure 3 This is an exploded schematic diagram of the ball screw pair of this utility model.

[0023] In the diagram: 10 Gear, 20 Bearing, 30 Ball bearing, 40 Lead screw shaft, 41 Stop pin, 50 Sleeve, 51 Corresponding mating part, 52 External connection structure, 53 Accessory mounting structure, 60 Nut, 61 Reversing device mounting hole, 62 Non-cylindrical mating part, 63 Reversing device, 64 Stop block. Detailed Implementation

[0024] The technical solution of this utility model will be clearly and completely described below with reference to its embodiments. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0025] Reference Figure 1-3 A ball screw assembly includes a screw shaft 40, a screw nut 60, a gear 10, and a bearing 20; the screw shaft 40 is an integral structure, and its axial direction is sequentially integrated with a gear section, a bearing section, and a threaded raceway section.

[0026] The gear segment is equipped with a gear 10 that directly meshes with the drive motor gear. The gear 10 is either a spur gear or a helical gear, and its tooth profile parameters are matched with the drive motor gear to achieve direct meshing transmission, providing the integrated lead screw shaft 40 with a power input end suitable for various working conditions. When the drive motor outputs torque, its end gear directly meshes with the tooth profile of the integrated gear 10 on the lead screw shaft 40, transmitting rotational power to the lead screw shaft 40 body without loss. If the gear 10 is a spur gear, efficient force transmission is achieved through instantaneous full-tooth contact in the tooth width direction; if it is a helical gear, the progressive meshing characteristics of the helix angle are used to suppress impact vibration.

[0027] The bearing section is equipped with a bearing 20, which is configured to provide an axial positioning surface for the inner ring of the bearing 20, providing a physical limiting reference for the bearing 20. The bearing section directly bears the axial load of the inner ring of the bearing 20 through the body structure of the lead screw shaft 40, precisely constraining the axial movement of the inner ring of the bearing 20 during high-speed rotation or reverse transmission. When the inner ring of the bearing 20 is assembled to the bearing section of the lead screw shaft 40, its end face forms a rigid surface contact with the pre-formed stepped surface or shoulder structure of the bearing section. At this time, the body of the lead screw shaft 40 acts as a physical stop for the inner ring of the bearing 20. When subjected to the rotational driving force input by the motor gear or the reverse thrust of the nut 60, this positioning surface absorbs all axial displacement tendencies of the inner ring of the bearing 20 through direct mechanical interference, forcibly maintaining zero relative axial displacement between the inner ring of the bearing 20 and the lead screw shaft 40, ensuring that the rotation center always coincides with the axis of the thread raceway section.

[0028] The threaded raceway section is threadedly connected to a nut 60, which has multiple reversing device mounting holes 61. Reversing devices 63 are installed in the reversing device mounting holes 61. The reversing devices 63, the nut 60, and the threaded raceway section all have built-in ball return channels, in which balls 30 are rolled. The balls 30 form a closed loop path between the lead screw shaft 40 and the ball return channel of the nut 60. Based on the semi-sealed protection of the sleeve 50, the multiple reversing device mounting holes 61 on the nut 60 provide direction conversion nodes for the balls 30 by precisely embedding the reversing devices 63. This allows the helical raceway inside the nut 60, the threaded raceway section of the lead screw shaft 40, and the built-in channel of the reversing device 63 to jointly form a continuous, through-type ball return path. This closed-loop design eliminates the risk of jamming when the ball 30 changes direction, ensuring that the ball group rolls uninterruptedly along the ball return channel when the lead screw shaft 40 rotates, thereby converting rotational friction into smooth axial thrust and significantly improving transmission smoothness and position control accuracy. When the lead screw shaft 40 rotates, the threaded raceway section pushes the balls 30 to roll along the helical raceway inside the lead screw nut 60. When the balls 30 reach the position of the reverser mounting hole 61, they are forcibly guided to change direction by the return ball channel of the reverser 63, realizing the continuous circulation of the balls 30 in a closed loop of "helical raceway → reverser direction → adjacent raceway". This process makes the ball group form a dynamic load chain between the lead screw shaft 40 and the lead screw nut 60, and efficiently converts the rotational torque into the linear displacement output of the lead screw nut 60 through low-friction rolling.

[0029] The lead screw shaft 40 integrates the gear section, bearing section, and threaded raceway section in an axial manner, compressing the three major functions of power input from the gear 10, rotational support from the bearing 20, and linear output from the lead screw nut 60 into a single shaft space, directly eliminating the transmission redundancy of the traditional split layout. The direct meshing between the gear 10 and the motor gear eliminates the intermediate gear train, the inner ring positioning of the bearing 20 ensures the coaxiality of the lead screw shaft 40, and the ball joint between the threaded raceway section and the lead screw nut 60 efficiently converts rotational motion into linear thrust. This achieves extreme simplification of the transmission chain and enhanced rigidity within the narrow space of the wheel edge, fundamentally solving the core defects of large space occupation and complex assembly in the background technology.

[0030] In some embodiments, a sleeve 50 is fitted around the outside of the nut 60, covering at least a portion of the outer periphery of the nut 60 to form a semi-sealed structure, thereby blocking the reverser mounting hole 61 on the nut 60 to inhibit lubricant leakage. Based on the high integration of the lead screw shaft 40, the sleeve 50, by covering at least a portion of the outer periphery of the nut 60 to form a semi-sealed enclosure structure, plays a crucial role in physically shielding the exposed reverser mounting hole 61 on the nut 60. This effectively blocks the path of lubricant splashing outwards due to centrifugal force during the circulation of the balls 30, while also isolating the risk of contaminants such as mud, water, and dust from the wheel-side environment entering the raceway through the reverser mounting hole 61. While maintaining heat dissipation and maintainability, this significantly improves the sealing reliability of the ball screw assembly under harsh automotive braking conditions. When the lead screw 60 rotates and makes axial displacement with the lead screw shaft 40, the sleeve 50, as a static protective shell, always wraps around the outer periphery of the lead screw 60; its coverage area places the reverser mounting hole 61 in a closed or semi-closed space, forming a dynamic sealing barrier around the orifice through a physical isolation mechanism: internally, it inhibits the leakage of grease splashed by the ball 30 from the reverser mounting hole 61, and externally, it blocks external contaminants from entering the raceway through the orifice, thereby achieving long-term stability of the lubrication system and clean operation of the moving parts through passive protection.

[0031] In some embodiments, an anti-rotation fitting structure is provided between the nut 60 and the sleeve 50 to constrain the nut 60 to move only axially. The anti-rotation fitting structure includes a non-cylindrical fitting portion 62 located at the end of the nut 60, and a corresponding fitting portion 51 located inside the sleeve 50 to fit the non-cylindrical fitting portion. The non-cylindrical fitting portion 62 has a flat rectangular structure, and the corresponding fitting portion 51 has a flat rectangular groove; the two fit together. Under the semi-sealed enclosure of the sleeve 50 around the nut 60, a rigid anti-rotation constraint mechanism is constructed through the embedded engagement of the non-cylindrical mating part 62 at the end of the nut 60 and the corresponding mating part 51 on the inner side of the sleeve 50. Its core value lies in completely eliminating the risk of circumferential rotation of the nut 60 when subjected to the torque transmitted by the ball 30, forcing the nut 60 to translate only along the axial direction of the lead screw shaft 40, completely converting the rotational motion into a pure linear output, ensuring that the braking thrust direction is precise and controllable, and at the same time avoiding the failure of the sleeve 50 seal or the loosening of the connection structure 52 due to the rotation of the nut 60, fundamentally ensuring the absolute reliability of the power transmission of the automotive braking system. When the lead screw shaft 40 rotates and drives the ball 30 to push the nut 60, the flat square structure 62 at the end of the nut 60 and the flat square groove 51 on the inner side of the sleeve 50 form a geometric interlock: the parallel plane of the flat square structure 62 is rigidly limited by the corresponding inner wall of the flat square groove 51, and the circumferential degree of freedom of the nut 60 is blocked by the mechanical interference of the non-rotationally symmetric contour, so that the tangential force generated by the ball 30 is completely converted into axial displacement, while any rotational tendency is absorbed by the static fixed structure of the sleeve 50, thereby realizing pure axial precise control of the movement trajectory of the nut 60.

[0032] In some embodiments, the end of the sleeve 50 is provided with an external connection structure 52 for adapting and connecting with an external braking assembly. The external connection structure 52 is a notch opened at the end of the sleeve 50. Based on the internal motion constraint achieved by the anti-rotation structure between the sleeve 50 and the nut 60, the external connection structure 52 at the end of the sleeve 50 is adapted and connected to the external braking assembly in the form of a notch. Its core function is to modularly anchor the entire ball screw pair to the braking actuator; through the snap-fit ​​positioning of the notch, the sleeve 50 achieves zero circumferential displacement and axial preload bearing, ensuring that the linear thrust output by the nut 60 is accurately transmitted to the brake caliper, while providing a stable mounting base for the semi-sealed sleeve 50, avoiding seal failure due to vibration, and fundamentally meeting the dual requirements of the automotive braking system for high rigidity connection and spatial adaptability of transmission components. When the positioning protrusion of the brake assembly is inserted into the notch 52 at the end of the sleeve 50, the vertical walls on both sides of the notch 52 form a rigid surface contact with the protrusion, directly absorbing the reaction torque generated when the nut 60 transmits axial thrust. The open structure of the notch 52 allows for rapid assembly and positioning, while its geometric constraints eliminate the circumferential movement of the sleeve 50 relative to the brake assembly through a mechanical interlocking mechanism, so that the pure linear displacement of the nut 60 is converted into the clamping motion of the brake caliper without loss, while maintaining the static stability of the semi-sealed protection of the sleeve 50.

[0033] In some embodiments, the outer wall of the sleeve 50 is provided with an accessory mounting structure 53 for installing a dust cover. The accessory mounting structure 53 is an annular groove. After the sleeve 50 is rigidly connected to the brake assembly through the notch 52, the annular groove 53 on its outer wall serves as the accessory mounting structure, providing a snap-fit ​​anchoring base for the dust cover. This design, through the circumferential continuous groove structure of the annular groove 53, ensures that the lip of the dust cover is evenly tightened around the outer wall of the sleeve 50. On the basis of the semi-sealed protection of the sleeve 50, a dynamic sealing layer is added, which completely blocks the path of fine dust and humid airflow in the wheel-side environment to enter the reverser mounting hole 61 along the axial gap of the sleeve 50. This significantly improves the sealing robustness of the ball screw pair under extreme working conditions, while avoiding the disassembly damage and increased maintenance costs caused by traditional adhesive or bolt fixing. When the elastic sealing lip of the dust cover is embedded in the annular groove 53 on the outer wall of the sleeve 50, the groove wall exerts a radial clamping force and an axial blocking effect on the sealing lip, forming a static sealing interface without relative sliding. This interface and the semi-sealed structure of the sleeve 50 work together to form a double barrier of "dynamic dust cover + static sleeve": when the axial displacement of the nut 60 causes the sleeve 50 to move slightly, the geometric constraint of the annular groove 53 keeps the dust cover in a pre-tightened state of the sealing lip, and dust and moisture are continuously blocked outside the protection system. The arc structure at the bottom of the groove avoids stress concentration and tearing of the sealing lip, ensuring long-term sealing reliability.

[0034] In some embodiments, an axial limiting structure is also included, comprising a stop pin 41 press-fitted onto the lead screw shaft 40 and a stop block 64 located at the end of the nut 60. The stop pin 41 and the stop block 64 cooperate to limit the axial travel endpoint of the nut 60 relative to the lead screw shaft 40, preventing return impact. The core function of the rigid cooperation between the stop pin 41 press-fitted onto the lead screw shaft 40 and the stop block 64 located at the end of the nut 60 is to precisely define the axial movement boundary of the nut 60 relative to the lead screw shaft 40. Its core function is to forcibly prevent further displacement of the nut 60 by utilizing the mechanical interference of the stop pin 41 and the stop block 64 when the nut 60 reaches the preset travel endpoint, effectively preventing severe impact caused by excessive return movement. This ensures the safety boundary and long-term working stability of the ball screw assembly under harsh operating conditions such as automotive braking systems, avoiding component damage or functional failure due to impact. When the lead screw shaft 40 rotates and drives the lead screw nut 60 to move along its axial direction, as the lead screw nut 60 gradually approaches the set maximum or minimum stroke position, the stop block 64 at its end will make physical contact with the stop pin 41 fixed on the lead screw shaft 40. At this time, the stop pin 41, as a rigid blocking point, will absorb the kinetic energy of the lead screw nut 60 instantaneously and forcibly stop its movement through the interaction with the stop block 64, thereby reliably limiting the axial stroke end position of the lead screw nut 60 and ensuring that it reciprocates within a safe range.

[0035] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A ball screw pair comprising a screw shaft (40), a nut (60), a gear (10), and a bearing (20), characterized in that, The lead screw shaft (40) is an integral structure, and its axial direction is sequentially integrated with a gear section, a bearing section and a threaded raceway section; The gear section is provided with a gear (10) that directly meshes with the drive motor gear for transmission; the bearing section is provided with a bearing (20); and the threaded raceway section is threadedly connected with a nut (60). The lead screw shaft (40) integrates the gear (10), bearing (20) and nut (60) to realize the functions of gear transmission, bearing support and ball screw transmission.

2. Ball screw pair according to claim 1, characterized in that The nut (60) is fitted with a sleeve (50) which covers at least a portion of the outer periphery of the nut (60) to form a semi-sealed structure, thereby blocking the reverser mounting hole (61) on the nut (60) to prevent lubricating grease leakage.

3. The ball screw assembly according to claim 2, characterized in that: The nut (60) is provided with a plurality of reverser mounting holes (61), and a reverser (63) is installed in the reverser mounting holes (61). The reverser (63), the nut (60) and the thread raceway section are all equipped with a ball return channel. The ball return channel is connected by rolling balls (30), and the balls (30) form a closed loop path between the ball return channel of the screw shaft (40) and the nut (60).

4. The ball screw pair according to claim 2, characterized in that: The nut (60) and the sleeve (50) are provided with an anti-rotation fit structure to constrain the nut (60) to move only along the axial direction.

5. Ball screw pair according to claim 4, characterized in that The anti-rotation mating structure includes a non-cylindrical mating part (62) provided at the end of the nut (60), and a corresponding mating part (51) provided inside the sleeve (50) to adapt to the non-cylindrical mating part.

6. The ball screw pair according to claim 2, characterized in that: The end of the sleeve (50) is provided with an external connection structure (52) for adapting and connecting with an external braking assembly.

7. The ball screw pair according to claim 2, characterized in that: The outer wall of the sleeve (50) is provided with an accessory mounting structure (53) for installing a dust cover.

8. The ball screw pair according to claim 1, characterized in that: It also includes an axial limiting structure, which includes a stop pin (41) press-fitted on the lead screw shaft (40) and a stop block (64) provided at the end of the lead nut (60); the stop pin (41) and the stop block (64) cooperate to limit the axial travel end position of the lead nut (60) relative to the lead screw shaft (40) and prevent return impact.

9. The ball screw pair according to claim 1, characterized in that: The bearing section is configured to provide an axial positioning surface for the inner ring of the bearing (20).

10. The ball screw pair according to claim 1, characterized in that: The gear (10) is either a spur gear or a helical gear, and its tooth profile parameters are matched with the gear of the drive motor to achieve direct meshing transmission.

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