Ball screw and electromechanical brake

Abstract

The utility model relates to brake technical field, specifically disclose a ball screw and electronic mechanical brake, the first lever of stud assembly includes the load department and the connecting portion along the axial arrangement, the load department is used for connecting the drive part, the first lever is coaxial with second lever setting and transmission connection, the connecting portion is inserted and fixed in second lever, second lever is provided with the threaded portion, the nut is covered in stud assembly outside and can relatively rotate, the circulating track is formed between the nut and threaded portion, the ball rolls in circulating track, the axle ring of thrust needle bearing is fixed with stud assembly, the race of thrust needle bearing is used for with the relative fixation of clamp body, thrust needle bearing, third gasket, second gasket are sequentially arranged along the axial direction, second gasket is fixed with second lever, third gasket is fixed with the axle ring of thrust needle bearing and is fixed and covered in first lever outside, ball hinge connection is connected between second gasket and third gasket. Relieve the bending force that occurs between the first lever and second lever.

Description

Technical Field

[0001] This utility model relates to the field of brake technology, and in particular to a ball screw and an electromechanical brake. Background Technology

[0002] Electromechanical brakes (EMBs), as a new generation of braking technology, offer significant advantages over traditional hydraulic braking systems, including faster response, higher control precision, and easier integration, and are considered the future direction of braking system development. In EMB systems, the ball screw is the core transmission component, and its performance directly affects the overall efficiency and reliability of the braking system.

[0003] In traditional ball screws, the balls circulate in the raceway between the nut and the screw to convert rotational motion into linear motion. However, when the nut is deflected by the reaction force of the brake block, the nut and screw are threaded together, and the nut's action on the screw causes it to also deflect. Since the screw connects the drive component and the nut, this deflection tendency affects two main aspects: firstly, it disrupts the circulation of the balls between the nut and the screw, impacting transmission efficiency and potentially causing ball jamming, leading to brake failure and seriously threatening vehicle safety; secondly, it affects the connection and locking between the screw and the output end of the drive component.

[0004] Therefore, there is an urgent need for a ball screw and electromechanical brake to solve the above problems. Utility Model Content

[0005] The purpose of this utility model is to provide a ball screw and an electromechanical brake to solve the problem of poor transmission between the screw and the drive component, and between the screw and the nut, when the nut is subjected to a force in a direction intersecting the axis.

[0006] On one hand, this utility model provides a ball screw and an electromechanical brake, the ball screw comprising:

[0007] A stud assembly includes a first rod and a second rod. The first rod includes a load portion and a connecting portion arranged axially. The load portion is used to connect a drive component. The first rod and the second rod are coaxially arranged. The connecting portion is inserted into and fixed in the second rod. The second rod is provided with a threaded portion.

[0008] Nut and ball, wherein the nut is sleeved on the stud assembly and the two are able to rotate relative to each other, and a circulating track is formed between the nut and the threaded portion, and the ball rolls in the circulating track;

[0009] A thrust needle roller bearing, wherein the shaft ring of the thrust needle roller bearing is fixed to the stud assembly, and the seat ring of the thrust needle roller bearing is used to fix it relative to the clamp body;

[0010] The second and third washers, the thrust needle roller bearing, the third washer, and the second washer are arranged sequentially along the axial direction. The second washer is fixed to the second rod, and the third washer is fixed to the shaft ring of the thrust needle roller bearing and is fixedly sleeved outside the first rod. The second and third washers are connected by a ball joint.

[0011] As a preferred embodiment of the ball screw, the load portion and the output end of the drive component are connected by a spline structure.

[0012] As a preferred embodiment of the ball screw, the stud assembly includes a first rod and a second rod. The first rod includes a load portion and a connecting portion arranged axially. The first rod and the second rod are coaxially arranged. The connecting portion is inserted into and fixed in the second rod. The second rod is provided with the threaded portion.

[0013] As a preferred embodiment of the aforementioned ball screw, the first member and the second member are connected by a spline structure.

[0014] As a preferred embodiment of the ball screw, it also includes a retaining ring. The connecting part of the first rod is a stepped shaft, including a large diameter section, a small diameter section and a shoulder formed between the two. The small diameter section passes through the second rod axially. The small diameter section has a retaining groove. Part of the retaining ring is inserted into the retaining groove. The second rod is clamped between the shoulder and the retaining ring.

[0015] As a preferred embodiment of the ball screw, the second rod has a first chamber on one axial side end face, and the first rod passes through the bottom wall of the first chamber and engages with the snap ring.

[0016] As a preferred embodiment of the ball screw, it further includes a wave spring, which is sleeved on the first member and sandwiched between the second member and the retaining ring. The wave spring causes the retaining ring to always have a tendency to move away from the second member along the axial direction.

[0017] As a preferred embodiment of the ball screw, it further includes a first washer, which is sandwiched between the retaining ring and the wave spring.

[0018] In a preferred embodiment of the ball screw, the threaded portion forms an external threaded guide rail, and the inner circumferential wall of the nut is provided with multiple raceways arranged sequentially along the axis of the nut. The raceways are annular and include a helical section and a connecting section. The helical section spirals around the axis of the nut, and the connecting section connects the two ends of the helical section. Multiple balls are provided and distributed within the multiple raceways. The balls can move along the raceways. When a ball is within the helical section, it is simultaneously located within the external threaded guide rail. When a ball is within the connecting section, it exits the external threaded guide rail.

[0019] As a preferred embodiment of the ball screw, the depth dimension of the connecting section is greater than the depth dimension of the helical section, and the connection between the connecting section and the helical section is provided with a rounded transition surface.

[0020] An electromechanical brake is also provided, including a caliper body and a brake block and a brake disc mounted in the caliper body, a drive member and the aforementioned ball screw, wherein the drive member is used to drive the aforementioned stud assembly to rotate about an axis, and the aforementioned nut is used to drive the aforementioned brake block to move axially relative to the aforementioned brake disc.

[0021] Beneficial effects:

[0022] This utility model provides a ball screw, including a stud assembly, a nut, balls, a thrust needle roller bearing, a second washer, and a third washer. The stud assembly includes a first rod and a second rod. The first rod includes a load portion and a connecting portion arranged axially. The load portion connects to a drive component. The first and second rods are coaxially arranged and drive-connected. The connecting portion is inserted into and fixed within the second rod. The second rod has a threaded portion. The nut and balls are fitted around the stud assembly and can rotate relative to each other. A circular track is formed between the nut and the threaded portion, and the balls roll within the circular track. The thrust needle roller bearing has its bearing ring fixed to the stud assembly, and its seat ring is fixed relative to the clamp body. The second and third washers are arranged axially in sequence. The second washer is fixed to the second rod, and the third washer is fixed to the bearing ring and fitted around the first rod. The second and third washers are connected by a ball joint.

[0023] For example, the stud assembly adopts a split design, with a first rod and a second rod, both of which are columnar structures. The first rod has a load-bearing part and a connecting part at its two axial ends, respectively. The load-bearing part is used to connect with the driving component, and the connecting part is coaxially inserted into the second rod and connected through a transmission structure. A gap is formed between the first rod and the second rod. When the driving component is started, the first rod rotates around its own axis, and the driving component drives the second rod to rotate through the first rod. The second rod has a threaded part on the side away from the first rod along its axial direction. A nut is sleeved on the threaded part. The nut and the stud assembly can rotate relative to each other around the axis, and a circular track is formed between the nut and the threaded part, and the ball rolls in the circular track. The second gasket is sleeved on the first rod and spaced apart from the first rod. The second gasket includes a first plane and an arc-shaped convex surface arranged opposite each other along the axial direction. The first plane is in close contact with the bottom wall of the second chamber. The third gasket is interference-fitted with the first rod and fixed thereto. The third gasket includes a second plane and an arc-shaped concave surface arranged opposite each other along the axial direction. The second plane is in close contact with the axial end face of the bearing. The arc-shaped concave surface and the arc-shaped convex surface are opposite to and in close contact to form a ball joint. Thus, when the nut is subjected to a force at an angle to its axis, the nut deflects. At the same time, the nut also acts on the second rod through the ball bearings, causing the second rod to shift in the same direction as the nut. The second washer, being in close contact with the second rod, also shifts in the same direction. Since the third washer is fixed against the clamp body through a thrust needle roller bearing and is ball-jointed with the second washer, the third washer remains relatively stationary with the clamp body, while rotating relative to the second washer. Simultaneously, the third washer suppresses the tendency of the first rod to deflect with the second rod, ensuring that the first rod is always coaxially aligned with the output end of the drive unit.

[0024] Thus, the separate design of the first and second rods facilitates production and processing. On the other hand, the assembly gap between the first and second rods allows for a small range of relative oscillation. When one of the first and second rods is subjected to external force and deflects to form an angle with the axis of the nut, the other can maintain its preset posture, reducing the bending force between the first and second rods. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the ball screw structure in an embodiment of the present invention;

[0026] Figure 2 This is a cross-sectional view of the ball screw in an embodiment of the present invention;

[0027] Figure 3 This is a cross-sectional view of the nut in an embodiment of this utility model;

[0028] Figure 4This is a schematic diagram of the electromechanical brake in an embodiment of this utility model.

[0029] In the picture:

[0030] 100. Ball screw;

[0031] 1. Stud assembly; 11. First rod; 111. Load-bearing part; 112. Connecting part; 12. Second rod; 121. External threaded guide rail; 122. First chamber; 123. Second chamber;

[0032] 2. Nut; 21. Spiral section; 22. Connecting section;

[0033] 3. Snap ring; 4. Wave spring; 5. First washer; 6. Thrust needle roller bearing; 7. Second washer; 8. Third washer;

[0034] 200, Brake block; 300, Brake disc; 400, Drive component; 500, Clamp body. Detailed Implementation

[0035] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0036] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this utility model and for 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. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "first position" and "second position" refer to two different positions. Moreover, "above," "on top of," and "over" the first feature in relation to the second feature includes the first feature directly above and diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "under," and "below" the first feature in relation to the second feature includes the first feature directly below and diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0037] 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; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0038] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0039] like Figures 1 to 4 As shown, this utility model provides a ball screw, including a stud assembly 1, a nut 2, balls, a thrust needle roller bearing 6, a second washer 7, and a third washer 8. The stud assembly 1 includes a first rod 11 and a second rod 12. The first rod 11 includes a load portion 111 and a connecting portion 112 arranged axially. The load portion 111 is used to connect to a drive component 400. The first rod 11 and the second rod 12 are coaxially arranged and connected for transmission. The connecting portion 112 is inserted and fixed inside the second rod 12, and the second rod 12 is provided with a threaded portion. The nut 2 and the balls are sleeved on the outside of the stud assembly 1 and can rotate relative to each other. A circulating track is formed between the nut 2 and the threaded portion. The ball bearings roll in the circulating track; the thrust needle roller bearing 6 has its shaft ring fixed to the stud assembly 1, and its seat ring is used to fix it relative to the clamp body 500; the second washer 7 and the third washer 8 are arranged sequentially along the axial direction, the second washer 7 is fixed to the second rod 12, the third washer 8 is fixed to the shaft ring of the thrust needle roller bearing 6 and is fixedly sleeved outside the first rod 11, and the second washer 7 and the third washer 8 are connected by a ball joint.

[0040] For example, the stud assembly 1 adopts a split design, with the first rod 11 and the second rod 12 being separate. Both the first rod 11 and the second rod 12 are columnar structures. The two axial ends of the first rod 11 are a load part 111 and a connecting part 112, respectively. The load part 111 is used to connect with the drive member 400. The connecting part 112 is coaxially inserted into the second rod 12 and connected through a transmission structure. A gap is formed between the first rod 11 and the second rod 12. When the drive member 400 is started, the first rod 11 rotates around its own axis. The drive member 400 drives the second rod 12 to rotate through the first rod 11. The second rod 12 is provided with a threaded part on the side away from the first rod 11 along the axial direction. A nut 2 is sleeved on the threaded part. The nut 2 and the stud assembly 1 can rotate relative to each other around the axis. A circular track is formed between the nut 2 and the threaded part, and the ball rolls in the circular track. The second gasket 7 is sleeved on the first rod 11 and spaced apart from the first rod 11. The second gasket 7 includes a first plane and an arc-shaped convex surface arranged opposite each other along the axial direction. The first plane is in close contact with the bottom wall of the second chamber 123. The third gasket 8 is interference-fitted with the first rod 11 and fixed thereto. The third gasket 8 includes a second plane and an arc-shaped concave surface arranged opposite each other along the axial direction. The second plane is in close contact with the axial end face of the bearing. The arc-shaped concave surface and the arc-shaped convex surface are opposite to and in close contact to form a ball joint. Thus, when nut 2 is subjected to a force at an angle to its axis, nut 2 deflects. At the same time, nut 2 also acts on the second rod 12 through the ball bearings, causing the second rod 12 to shift in the same direction as nut 2. The second washer 7, being in close contact with the second rod, also shifts in the same direction. Since the third washer 8 is fixed against the clamp body 500 through the thrust needle roller bearing 6 and is ball-jointed with the second washer 7, the third washer 8 remains relatively stationary with the clamp body 500, while rotating relative to the second washer 7. Simultaneously, the third washer 8 suppresses the tendency of the first rod 11 to deflect with the second rod 12, ensuring that the first rod 11 is always coaxially aligned with the output end of the drive unit 400.

[0041] Thus, the separate design of the first rod 11 and the second rod 12 facilitates production and processing. On the other hand, the assembly gap between the first rod 11 and the second rod 12 allows for a small range of relative oscillation. When one of the first rod 11 and the second rod 12 is subjected to external force and deflects to form an angle with the axis of the nut, the other can maintain its preset posture, reducing the bending force between the first rod 11 and the second rod 12.

[0042] Optionally, the load section 111 is connected to the output end of the drive member 400 via a spline structure. This ensures stable transmission between the first rod 11 and the drive member 400.

[0043] Optionally, the first member 11 and the second member 12 are connected by a spline structure.

[0044] For example, a spline groove is provided at the center of the second rod 12, and the spline groove is opened along the axial direction. The connecting part 112 of the first rod 11 forms an external spline, which is inserted into the spline groove. The spline structure can restrict the relative rotation of the first rod 11 and the second rod 12. In this way, it can be ensured that when one of the first rod 11 and the second rod 12 is driven to rotate around the axis, the other can also rotate around the axis.

[0045] Optionally, the ball screw 100 also includes a retaining ring 3. The connecting part 112 of the first rod 11 is a stepped shaft, including a large diameter section, a small diameter section and a shoulder formed between the two. The small diameter section passes through the second rod 12 axially. The small diameter section has a retaining groove. Part of the retaining ring 3 is inserted into the retaining groove. The second rod 12 is clamped between the shoulder and the retaining ring 3.

[0046] For example, an external spline is formed on the small diameter section, and the end of the small diameter section facing away from the large diameter section passes through the second rod 12 and extends out of the second rod 12. The retaining ring 3 is inserted into the retaining groove, and the retaining ring 3 and the shoulder form an axial limit between the first rod 11 and the second rod 12.

[0047] Optionally, a first chamber 122 is provided on one side of the axial end face of the second rod 12, and the first rod 11 passes through the bottom wall of the first chamber 122 and is engaged with the snap ring 3.

[0048] For example, the second rod 12 has an inward recess on the axial side of the load portion 111 opposite to the first rod 11 to form a first chamber 122, and the retaining spring 3 abuts against the bottom of the first chamber 122, thereby shortening the length of the connecting portion 112 of the first rod 11.

[0049] Optionally, the ball screw 100 also includes a wave spring 4, which is sleeved on the first rod 11 and clamped between the second rod 12 and the retaining ring 3. The wave spring 4 makes the retaining ring 3 always have a tendency to move away from the second rod 12 along the axial direction.

[0050] With this configuration, the wave spring 4 ensures that the retaining ring 3 always abuts against the side wall of the retaining groove away from the load part 111, and also ensures that the shoulder of the first rod 11 always abuts against the axial end face of the second rod 12 along the axial direction, thereby achieving axial positioning of both the first rod 11 and the second rod 12.

[0051] Optionally, the ball screw 100 may also include a first washer 5, which is sandwiched between the retaining ring 3 and the wave spring 4.

[0052] With this configuration, the first pad 5 can be used for anti-slip purposes, so that the first pad 5 and the retaining spring 3 can form a flexible contact.

[0053] Optionally, the threaded portion forms an external threaded guide rail 121. The inner circumferential wall of the nut 2 is provided with multiple raceways, which are arranged sequentially along the axis of the nut 2. The raceways are annular and include a helical section 21 and a connecting section 22. The helical section 21 is helical around the axis of the nut 2, and the connecting section 22 connects the two ends of the helical section 21. Balls are sandwiched between the nut 2 and the stud assembly 1. Multiple balls are provided and distributed in multiple raceways. The balls can move along the raceways. When a ball is in the helical section 21, it is also in the external threaded guide rail 121. When the ball is in the connecting section 22, it exits the external threaded guide rail 121.

[0054] For example, the threaded portion is provided with an external threaded guide rail 121, which is a groove spirally opened around its own axis. The inner sidewall of the nut 2 is provided with multiple raceways, which are opened around the axis of the nut 2. Each raceway is 360°, that is, a complete ring. Among the multiple raceways, two raceways adjacent to each other along the axial direction are not connected. Each raceway includes a spiral segment 21 and a connecting segment 22. The spiral segment 21 is a groove spirally opened around the axis of the nut 2. The projection of the spiral segment 21 along the axial direction is C-shaped, that is, the angle of the spiral segment 21 is less than 360°. It can also be understood that any generatrix of the nut 2 only intersects with the spiral segment 21 of the same raceway at one point. The connecting segment 22 is connected to the spiral segment 21 end by end. When the stud assembly 1 rotates around its own axis, the nut 2 rotates relative to the stud assembly 1, and the nut 2 moves linearly along the axial direction. The ball is used for transmission between the stud assembly 1 and the nut 2 to improve transmission efficiency. When the ball is in the helical section 21, it is also in the external thread guide 121. At this time, the ball is used for transmission between the stud assembly 1 and the nut 2. When the ball enters the connecting section 22 from the tail end of the helical section 21, since the extension direction of the connecting section 22 is opposite to the extension direction of the external thread guide 121, the ball is squeezed out of the external thread guide 121 and returns to the beginning of the thread section along the connecting section 22. At this time, the ball does not participate in transmission. When the ball re-enters the helical section 21, it re-participates in transmission.

[0055] By placing the raceway on the inner circumferential wall of the nut 2, the use of inverters is reduced, which can both reduce the overall size of the ball screw 100 and improve its reliability.

[0056] It should be noted that since the balls do not have a transmission function when they are in the connecting section 22, in order for the nut 2 and the stud assembly 1 to continue to transmit power, at least one of the multiple raceways must have a stud assembly 1 participating in the transmission within its helical section 21 at any given time. Preferably, each raceway is provided with multiple balls, and the length of the multiple balls connected sequentially is greater than the length of the connecting section 22. In this way, it can be ensured that each raceway's helical section 21 always has balls participating in the transmission.

[0057] Optionally, the depth dimension of the connecting segment 22 is greater than the depth dimension of the helical segment 21, and the connection between the connecting segment 22 and the helical segment 21 is provided with a rounded transition surface. This configuration allows the ball to switch more smoothly between the helical segment 21 and the connecting segment 22.

[0058] An electromechanical brake is also provided, including a caliper body 500 and a brake block 200, a brake disc 300, a drive member 400 and the aforementioned ball screw 100 installed in the caliper body 500. The drive member 400 is used to drive the stud assembly 1 to rotate around the axis, and the nut 2 is used to drive the brake block 200 to move axially relative to the brake disc 300.

[0059] For example, the clamp body 500 provides an assembly carrier for other parts, the main body of the drive component 400 is mounted on the clamp body 500, the output end of the drive component 400 is connected to the load part 111 of the stud assembly 1 of the ball screw 100, the brake disc 300 is fixed relative to the clamp body 500, and the brake block 200 is fixed to the nut 2. When the stud assembly 1 rotates around the axis, the nut 2 can drive the brake block 200 to move closer to or away from the brake disc 300 along the axial direction.

[0060] Optionally, a second chamber 123 is provided on the other end face of the second rod 12, and the thrust needle roller bearing 6, the third washer 8, and the second washer 7 are arranged sequentially along the axial direction in the second chamber 123.

[0061] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating the present utility model, and are not intended to limit the implementation of the present utility model. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.

Claims

1. A ball screw, characterized in that, include: The stud assembly (1) includes a first rod (11) and a second rod (12). The first rod (11) includes a load portion (111) and a connecting portion (112) arranged axially. The load portion (111) is used to connect to the drive member (400). The first rod (11) and the second rod (12) are coaxially arranged and connected in transmission. The connecting portion (112) is inserted into and fixed in the second rod (12). The second rod (12) is provided with a threaded portion. Nut (2) and ball, wherein the nut (2) is sleeved on the stud assembly (1) and the two can rotate relative to each other, and a circular track is formed between the nut (2) and the threaded part, and the ball rolls in the circular track; A thrust needle roller bearing (6) is provided, wherein the shaft ring of the thrust needle roller bearing (6) is fixed to the stud assembly (1), and the seat ring of the thrust needle roller bearing (6) is used to be fixed relative to the clamp body (500). The second washer (7) and the third washer (8) are arranged in sequence along the axial direction. The second washer (7) is fixed to the second rod (12). The third washer (8) is fixed to the shaft ring of the thrust needle roller bearing (6) and is fixedly sleeved outside the first rod (11). The second washer (7) and the third washer (8) are connected by a ball joint.

2. The ball screw according to claim 1, characterized in that, The load unit (111) is connected to the output end of the drive unit (400) via a spline structure.

3. The ball screw according to claim 1, characterized in that, The first rod (11) and the second rod (12) are connected by a spline structure.

4. The ball screw according to claim 1, characterized in that, It also includes a retaining ring (3). The connecting part (112) of the first rod (11) is a stepped shaft, including a large diameter section, a small diameter section and a shoulder formed between the two. The small diameter section passes through the second rod (12) axially. The small diameter section has a retaining groove. Part of the retaining ring (3) is inserted into the retaining groove. The second rod (12) is sandwiched between the shoulder and the retaining ring (3).

5. The ball screw according to claim 4, characterized in that, The second rod (12) has a first chamber (122) on one side of its axial end face. The first rod (11) passes through the bottom wall of the first chamber (122) and is engaged with the snap ring (3).

6. The ball screw according to claim 4, characterized in that, It also includes a wave spring (4), which is sleeved on the first rod (11) and sandwiched between the second rod (12) and the retaining ring (3). The wave spring (4) causes the retaining ring (3) to always have a tendency to move away from the second rod (12) along the axial direction.

7. The ball screw according to claim 6, characterized in that, It also includes a first gasket (5), which is sandwiched between the retaining ring (3) and the wave spring (4).

8. The ball screw according to claim 1, characterized in that, The threaded portion forms an external threaded guide rail (121). The inner circumferential wall of the nut (2) is provided with multiple raceways. The multiple raceways are arranged sequentially along the axis of the nut (2). The raceways are annular and include a helical section (21) and a connecting section (22). The helical section (21) spirals around the axis of the nut (2). The connecting section (22) connects the beginning and end of the helical section (21). Multiple balls are provided and distributed in the multiple raceways. When a ball is in the helical section (21), the ball is simultaneously located in the external threaded guide rail (121). When the ball is in the connecting section (22), it exits the external threaded guide rail (121).

9. The ball screw according to claim 8, characterized in that, The depth dimension of the connecting segment (22) is greater than the depth dimension of the spiral segment (21), and the connection between the connecting segment (22) and the spiral segment (21) is provided with an arc surface transition.

10. An electromechanical brake, characterized in that, The device includes a clamp body (500) and a brake block (200), a brake disc (300), a drive member (400), and a ball screw (100) according to any one of claims 1-9, wherein the drive member (400) is used to drive the stud assembly (1) to rotate about an axis, and the nut (2) is used to drive the brake block (200) to move axially relative to the brake disc (300).

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