Ball screw structure with holder and linear actuator

Abstract

The utility model discloses a ball screw structure with a retainer and a linear actuator, and belongs to the technical field of transmission structures, the ball screw structure comprises a nut, a screw rod, a ball and a retainer, the nut is provided with a through hole and a first spiral groove arranged on the hole wall of the through hole, the screw rod is provided with a transmission part, a second spiral groove is arranged on the peripheral surface of the transmission part, and the second spiral groove is provided with a second spiral groove. The ball is arranged in a roller path formed by matching the first spiral groove and the second spiral groove, the retainer is provided with an accommodating part for accommodating the ball, the accommodating part spirally extends and is consistent with the spiral of the roller path, and a limiting structure for keeping the ball in the accommodating part is arranged on the inner wall of the accommodating part; the balls moving along the raceways drive the retainer to move, and the balls can rotate in the containing parts. The rolling balls are kept in the containing parts through the limiting structures, the rolling balls are prevented from being separated from the retainer, and due to the fact that the rolling balls are installed on the retainer in advance, whether the rolling balls are full or not is conveniently confirmed during assembling, and therefore the production efficiency and the assembling efficiency can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of transmission structures, in particular to a ball screw structure with a retaining frame. In addition, the utility model also relates to a linear actuator adopting the ball screw structure. Background Art

[0002] The ball screw structure generally includes a screw rod, a nut and a ball arranged between the two. A spiral raceway for the ball to move is formed between the outer circumference of the screw rod and the inner circumference of the nut. The movement of the ball converts rotational motion into linear motion, or converts linear motion into rotational motion.

[0003] During the operation of the ball screw structure, since the balls move unidirectionally in the spiral raceway, in order to allow the balls that have moved to the end of the raceway to return to the raceway, a return structure is generally provided on the nut. The two ends of the return structure are respectively connected to the two ends of the raceway. The balls that have moved to the end of the raceway return to the beginning of the raceway through the return structure, thereby allowing the balls to circulate. In order to ensure that the balls can smoothly return to the raceway through the return structure, the structural requirements and precision requirements of the return structure are high. This makes the processing of the return structure more difficult, which is not conducive to improving the production efficiency and assembly efficiency of the product. In addition, when a return structure is provided on the nut or the screw rod, the nut and the screw rod are generally combined together before the balls are inserted. Since the inserted balls are not visible, it is impossible to quickly determine whether the balls are fully filled during the assembly process, which is not conducive to improving the assembly efficiency. Utility Model Content

[0004] In order to solve the shortcomings and deficiencies in the above-mentioned prior art, the utility model provides a ball screw structure with a retaining frame, which uses a limiting structure to retain the balls in the receiving portion to prevent the balls from escaping from the retaining frame. Moreover, since the balls are installed on the retaining frame in advance, it is convenient to confirm whether the balls are full during assembly, which is conducive to improving production efficiency and assembly efficiency.

[0005] In order to achieve the above technical objectives, the utility model provides a ball screw structure with a cage, comprising:

[0006] The nut has a through hole and a first spiral groove provided on the wall of the through hole;

[0007] A screw rod having a transmission portion cooperating with the nut, wherein a second spiral groove is provided on an outer circumference of the transmission portion;

[0008] The first spiral groove and the second spiral groove cooperate to form a spiral raceway, at least a portion of the raceway has a plurality of balls distributed along the raceway, and the balls move along the raceway when the nut or the screw is braked;

[0009] The ball screw structure also includes a retaining frame arranged between the transmission part and the nut, the retaining frame is provided with a receiving portion for installing balls, the receiving portion extends spirally and is consistent with the spiral of the raceway, and the inner wall of the receiving portion is provided with a limiting structure for retaining the balls in the receiving portion. The balls moving along the raceway drive the retaining frame to move and the balls can rotate in the receiving portion.

[0010] Preferably, the limiting structure includes a first limiting surface and a second limiting surface which are arranged on the inner wall of the receiving portion and distributed inside and outside. The first limiting surface and the second limiting surface are set at an obtuse angle, and the minimum distance between the first limiting surface and the second limiting surface and the center line of the receiving portion respectively is less than the diameter of the ball.

[0011] Preferably, the first limiting surface is directly formed on the inner wall of the accommodating portion; or, the first limiting surface is formed by spot welding.

[0012] Preferably, the second limiting surface is formed by riveting a part of the inner wall of the accommodating portion; or, the second limiting surface is formed by spot welding.

[0013] Preferably, an included angle θ between the first limiting surface and the second limiting surface is 140° to 160°.

[0014] Preferably, the retaining frame is in a hollow cylindrical shape, the receiving portion is a receiving hole provided on the retaining frame, and a plurality of the receiving holes are provided at intervals along the same spiral track as the raceway.

[0015] Preferably, the retaining frame is in a hollow cylindrical shape, the receiving portion is a receiving groove provided on the retaining frame, and the receiving groove extends spirally.

[0016] Preferably, the receiving grooves are continuously arranged and extend from one end to the other end of the retaining frame; or, the receiving grooves are spaced apart and are spaced apart in at least two sections along the axial direction of the retaining frame.

[0017] Preferably, the inner diameter of the retaining frame is larger than the outer diameter of the transmission part, and the outer diameter of the retaining frame is smaller than the inner diameter of the through hole.

[0018] The present invention also provides a linear actuator, including a housing, a stator module and the above-mentioned ball screw structure with a retaining frame. The ball screw structure is arranged in the housing and the screw rod can extend out of the housing. The nut is axially positioned and rotatably mounted in the housing, and the stator module is axially positioned and sleeved on the outside of the nut.

[0019] After adopting the above technical solution, the utility model has the following advantages:

[0020] 1. The ball screw structure provided by the present invention comprises a retainer disposed between the transmission portion and the nut, the retainer being provided with a receiving portion, and a limiting structure disposed on the inner wall of the receiving portion. During assembly, the balls are first loaded into the receiving portion of the retainer, and the limiting structure is used to retain the balls in the receiving portion to prevent the balls from escaping the retainer. The screw, the retainer containing the balls, and the transmission nut are then assembled together. Since the balls are pre-installed on the retainer, it is convenient to confirm whether the balls are fully loaded during assembly, thereby improving assembly efficiency. When either the nut or the screw is actuated, the balls move along the raceway and drive the other, and the movement of the balls along the raceway also drives the retainer. That is, the balls are always located between the transmission portion of the screw and the nut, eliminating the need for a conventional return device, significantly reducing structural and precision requirements, and improving production efficiency. If a portion of the retainer is dislodged from the screw and nut, the balls remain retained in the receiving portion by the limiting structure, preventing them from falling out of the retainer, thereby improving the integrity and stability of the overall structure.

[0021] 2. The limiting structure includes a first limiting surface and a second limiting surface. The two limiting surfaces are distributed at obtuse angles, and the minimum distance between the two limiting surfaces and the center line of the receiving portion is less than the diameter of the ball. The limiting structure is reasonably arranged, and the inner wall of the receiving portion is made into a bidirectional conical structure through the two limiting surfaces, so that the ball arranged in the receiving portion is subject to bidirectional limitation in the same radial direction, thereby effectively keeping the ball in the receiving portion and preventing the ball from escaping from the receiving portion.

[0022] 3. The first limiting surface can be formed directly from a portion of the inner wall of the receiving portion, or it can be formed by spot welding. The second limiting surface can be formed from a portion of the inner wall of the receiving portion by riveting, or it can be formed by spot welding. Reasonable arrangements are made to form the two limiting surfaces, thereby reducing the difficulty of forming the limiting surfaces and ensuring that the limiting surfaces meet the ball limiting requirements.

[0023] 4. Reasonably set the angle θ between the two limiting surfaces so that the limiting structure can retain the ball in the receiving portion. If the angle θ is less than 140°, the two limiting surfaces will be difficult to form, making it difficult to process. If the angle θ is greater than 160°, the contact point between the two limiting surfaces and the ball is far from the ball's center, and the limiting structure will not be able to stably retain the ball in the receiving portion.

[0024] 5. The receiving portion can be a plurality of receiving holes spaced apart along the spiral direction, or a receiving groove extending along the spiral. The receiving groove can be arranged continuously or in sections. The specific structure of the receiving portion is reasonably set to meet the structural requirements for installing the ball, so that the ball can meet the transmission requirements between the screw rod and the nut.

[0025] 6. The inner diameter of the cage is larger than the outer diameter of the transmission part. At the same time, the outer diameter of the cage is smaller than the inner diameter of the through hole on the nut. The size of the cage should be reasonably set so that the cage does not contact the nut or the screw as much as possible, avoiding interference between the cage and the transmission between the nut and the screw, thereby improving the transmission accuracy and stability of the structure.

[0026] 7. The linear actuator provided by the present invention uses a ball screw structure as a rotor module. The screw of the ball screw structure can move forward or backward when the linear actuator is working. The push-pull action can be achieved by utilizing the movement of the screw. This not only reduces the assembly workload of the linear actuator structure, but also can reasonably and linearly reduce the axial length of the actuator structure, so that the linear actuator can better meet the linear actuation requirements in a small space. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is an overall diagram of the ball screw structure of Example 1;

[0028] Figure 2 An exploded view of the ball screw structure of Example 1;

[0029] Figure 3 This is an axial cross-sectional view of the ball screw structure of Example 1;

[0030] Figure 4 An axial cross-sectional view of a ball screw structure in accordance with the first embodiment, wherein the ball screw and the nut cooperate to form a raceway;

[0031] Figure 5 This is an axial cross-sectional view of the nut in the ball screw structure of Example 1;

[0032] Figure 6 This is a structural diagram of the retaining frame in the ball screw structure of Example 1 in the initial state;

[0033] Figure 7 This is a structural diagram of the retaining frame in the ball screw structure of Example 1 after riveting;

[0034] Figure 8a This is a partial structural diagram of the retaining frame in the ball screw structure of Example 1 in the initial state;

[0035] Figure 8b This is a partial structural diagram of the retaining frame in the ball screw structure of Example 1 when the receiving hole is stuffed with balls;

[0036] Figure 8c This is a partial structural diagram of the retaining frame in the ball screw structure of Example 1 after riveting;

[0037] Figure 9 is an axial cross-sectional view of the linear actuator of Example 1;

[0038] Figure 10This is a structural diagram of the retaining frame in the ball screw structure of Example 2 after spot welding;

[0039] Figure 11 This is a partial structural diagram of the retaining frame in the ball screw structure of Example 2 after spot welding;

[0040] Figure 12a This is a structural diagram of the initial state of the retaining frame in the ball screw structure of Example 4 when the receiving grooves are continuously arranged;

[0041] Figure 12b This is a structural diagram of the ball screw structure in the fourth embodiment after the retaining frame is riveted when the receiving grooves are continuously arranged;

[0042] Figure 13 This is a structural diagram of the ball screw structure in Example 4 after the retaining frame is riveted when the receiving groove is segmented.

[0043] In the figure, 10-ball screw structure, 100-nut, 110-through hole, 120-first spiral groove,

[0044] 200-screw, 210-transmission part, 220-second spiral groove, 230-rod,

[0045] 300-roller,

[0046] 400-ball,

[0047] 500 - retaining frame, 510 - receiving portion, 511 - receiving hole, 511a - hole wall, 512 - receiving groove, 520 - limiting structure, 521 - first limiting surface, 522 - second limiting surface, 523 - limiting block.

[0048] 1000-Linear Actuator,

[0049] 20- housing, 21- main housing, 22- front cover, 23- rear cover, 24- support frame, 25- oil filling hole, 30- stator module, 41- front connector, 42- rear connector, 50- encoder, 60- control board. DETAILED DESCRIPTION

[0050] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the following terms indicating orientations or positional relationships, such as "upper," "lower," "left," "right," "longitudinal," "lateral," "inner," "outer," "vertical," "horizontal," "top," and "bottom," are based solely on the orientations or positional relationships shown in the accompanying drawings and are intended solely for the purpose of facilitating and simplifying the description of the present invention. They do not indicate or imply that the device or element referred to must have a specific orientation or be constructed or operated in a specific orientation, and therefore should not be construed as limiting the present invention.

[0051] Example 1

[0052] Combine Figures 1 to 8c The ball screw structure 10 with a retainer provided in the first embodiment of the present invention includes:

[0053] The nut 100 has a through hole 110 and a first spiral groove 120 provided on the wall of the through hole 110;

[0054] The screw rod 200 has a transmission portion 210 that cooperates with the nut 100, and a second spiral groove 220 is provided on the outer circumference of the transmission portion 210;

[0055] The first spiral groove 120 cooperates with the second spiral groove 220 to form a spiral raceway 300. At least a portion of the raceway 300 has a plurality of balls 400 distributed along the raceway. The balls 400 move along the raceway 300 when the nut 100 or the screw rod 200 is braked.

[0056] The ball screw structure 10 also includes a retaining frame 500 arranged between the transmission part 210 and the nut 100. The retaining frame 500 is provided with a receiving portion 510 for installing the ball 400. The receiving portion 510 extends spirally and is consistent with the spiral of the raceway 300. The inner wall of the receiving portion 510 is provided with a limiting structure 520 for retaining the ball 400 in the receiving portion 510. The ball 400 moving along the raceway 300 drives the retaining frame 500 to move and the ball 400 can rotate in the receiving portion 510.

[0057] During assembly, the ball 400 is first loaded into the receiving portion 510 of the retainer 500, and the limiting structure 520 is used to retain the ball 400 in the receiving portion 510 to prevent the ball 400 from escaping from the retainer 500. Then, the screw 200, the retainer 500 containing the ball 400, and the transmission nut 100 are assembled together. Since the ball 400 is pre-installed on the retainer 500, it is convenient to confirm whether the ball 400 is fully loaded during assembly, which is conducive to improving assembly efficiency. When one of the nut 100 or the screw 200 is actuated, the ball 400 moves along the raceway 300 and drives the other to move. When the ball 400 moves along the raceway 300, it also drives the retainer 500 to move. That is, the ball 400 is always located between the transmission portion 210 of the screw 200 and the nut 100. There is no need to set a conventional returner, which can greatly reduce the structural requirements and precision requirements, and is conducive to improving production efficiency. When a portion of the retaining frame 500 is disengaged from the screw 200 and the nut 100, the ball 400 is still retained in the receiving portion 510 under the action of the limiting structure 520, preventing the ball 400 from falling from the retaining frame 500, which is beneficial to improving the overall integrity and stability of the structure.

[0058] In this embodiment, the screw rod 200 also includes a rod portion 230. The rod portion 230 and the transmission portion 210 can be integrally formed or separately formed and then fixed together. The outer diameter of the transmission portion 210 can be greater than the outer diameter of the rod portion 230, and the outer diameter of the transmission portion 210 can also be consistent with the outer diameter of the rod portion 230. The retaining frame 500 is hollow and cylindrical. In order to avoid interference between the retaining frame 500 and the transmission between the nut 100 and the screw rod 200, the inner diameter D1 of the retaining frame 500 is greater than the outer diameter D3 of the transmission portion 210, and the outer diameter D2 of the retaining frame 500 is less than the inner diameter D4 of the through hole 110. Specifically, D1-D3 can be set to reasonable sizes such as 0.5mm, 0.7mm, 1mm, 1.2mm, 1.5mm, 1.7mm, 2mm, etc., and D4-D2 can be set to reasonable sizes such as 0.5mm, 0.7mm, 1mm, 1.2mm, 1.5mm, 1.7mm, 2mm, etc.

[0059] In this embodiment, the receiving portion 510 is a plurality of receiving holes 511 provided on the retainer 500. The plurality of receiving holes 511 are spaced apart along the same spiral trajectory as the raceway 300, thereby allowing the balls 400 mounted on the retainer 500 to be simultaneously located within the raceway 300. The spiral distribution of the receiving holes 511 is consistent with the spiral of the raceway 300, meaning that the helix angle and spiral direction of the two spirals are consistent.

[0060] The aperture of the receiving hole 511 is slightly larger than the outer diameter of the ball 400, so that the ball 400 can roll freely in the receiving hole 511. In this embodiment, the limiting structure 520 includes a first limiting surface 521 and a second limiting surface 522 which are arranged on the inner wall of the receiving portion 510 and distributed inside and outside. The first limiting surface 521 and the second limiting surface 522 are set at an obtuse angle, and the minimum distance between the first limiting surface 521 and the second limiting surface 522 and the center line of the receiving portion 510 is less than the radius R of the ball 400. Specifically, the first limiting surface 521 and the second limiting surface 522 are formed by the hole wall 511a of the receiving hole 511. The retaining frame 500 has a certain thickness, and the side facing the central axis L1 of the retaining frame 500 is defined as the inner side, and the side away from the central axis L1 of the retaining frame 500 is positioned as the outer side. Combined with Figure 8a In the initial state, the receiving hole 511 is roughly in the shape of a cone, the inner diameter D5 of the receiving hole 511 is smaller than the outer diameter D6 of the receiving hole 511, the inner diameter D5 is slightly smaller than the outer diameter of the ball 400, and the outer diameter D6 is slightly larger than the outer diameter of the ball 400. Figure 8bWhen installing, first insert the ball 400 into the receiving hole 511 on the retainer 500 from the outside, and the ball 400 is partially embedded in the receiving hole 511 and abuts against the hole wall 511a of the receiving hole 511. The ball 400 protrudes from the inner and outer peripheral surfaces of the retainer 500 at the same time. Then, the retainer 500 is riveted, so that the part of the retainer 500 located on the outer periphery of the receiving hole 511 undergoes a certain deformation, and the local hole wall 511a on the outer side of the receiving hole 511 deforms toward the center of the receiving hole 511. The part inside the hole wall 511a forms a first limiting surface 521, and the part outside the hole wall 511a forms a second limiting surface 522 after the retainer 500 is riveted. The first limiting surface 521 and the second limiting surface 522 combine to form a bidirectional tapered hole structure. Through the bidirectional tapered hole structure, the ball 400 is always subject to bidirectional limitation in a certain radial direction, thereby stably retaining the ball 400 in the receiving hole 511. Therefore, in this embodiment, the first limiting surface 521 is directly formed by the inner wall 511a of the receiving hole 511, that is, the first limiting surface 521 is formed on the inner wall of the receiving hole 511, and the second limiting surface 522 is formed by riveting the outer wall 511 of the receiving hole 511. The minimum distance E1 between the first limiting surface 521 and the centerline L2 of the receiving hole 511 is less than the radius R of the ball 400, and the minimum distance E2 between the second limiting surface 522 and the centerline L2 of the receiving hole 511 is less than the radius R of the ball 400. Specifically, E1 and E2 are generally consistent. In order to maintain the retaining effect of the limiting structure 520 on the ball 400, R-E1 (E2) can be set according to the radius R of the ball 400. R-E1 (E2) can be specifically set to reasonable sizes such as 0.02mm, 0.05mm, 0.07mm, 1mm, 1.2mm, 1.4mm, 1.6mm, 1.8mm, and 2mm.

[0061] An angle θ is formed between the first limiting surface 521 and the second limiting surface 522, and the angle θ is 140°≤θ≤160°. Specifically, in this embodiment, the angle θ is approximately 150°. As an alternative to this embodiment, the angle θ can also be set to 140°, 142°, 145°, 147°, 149°, 152°, 155°, 157°, 160°, or other reasonable values.

[0062] During assembly, the balls 400 are first loaded into the receiving holes 511, and then the retainer 500 is riveted. The first limiting surface 521 and the second limiting surface 522 are formed by the hole wall 511a of the receiving hole 511. The balls 400 are retained in the receiving holes 511 by the double-tapered hole structure formed by the first limiting surface 521 and the second limiting surface 522. After all the receiving holes 511 are filled with the balls 400, the retainer 500 with the balls 400 is screwed onto the outside of the transmission part 210, and the nut 100 is then screwed onto the outside of the retainer 500. The portion of the balls 400 protruding outward from the outer circumference of the retainer 500 is embedded in the first spiral groove 120, and the portion of the balls 400 protruding inward from the inner circumference of the retainer 500 is embedded in the second spiral groove 220.

[0063] When the screw rod 200 is actuated as an active part, the axial length of the transmission part 210 is greater than the axial length of the nut 100, and the axial length of the retaining frame 500 can be approximately equal to or slightly less than the axial length of the nut 100. The actuated screw rod 200 drives the nut 100 to move through the cooperation of the ball 400 and the raceway 300, and the ball 400 moving in the raceway 300 drives the retaining frame 500 to perform spiral motion, that is, the retaining frame 500 performs axial movement and circumferential rotation at the same time.

[0064] When the nut 100 is actuated as an active part, the axial length of the nut 100 is greater than the axial length of the transmission part 210, and the axial length of the retaining frame 500 can be approximately equal to or slightly less than the axial length of the transmission part 210. When the nut 100 rotates, the screw rod 200 is driven to move through the cooperation between the ball 400 and the raceway 300. The ball 400 moving in the raceway 300 drives the retaining frame 500 to perform spiral motion, that is, the retaining frame 500 performs axial movement and circumferential rotation at the same time.

[0065] As an optional solution of this embodiment, the second limiting surface 522 formed by press riveting can form a circle along the circumference of the receiving hole 511, or can be provided in at least two sections at intervals along the circumference of the receiving hole 511.

[0066] Combine Figure 9This embodiment also provides a linear actuator 1000, comprising a housing 20, a stator module 30, and the aforementioned ball screw structure 10. The ball screw structure 10 is disposed within the housing 20, and a screw 200 can extend out of the housing 20. A nut 100 is axially positioned and rotatably mounted within the housing 20, and the stator module 30 is axially positioned and sleeved on the exterior of the nut 100. The ball screw structure 10 directly serves as the rotor module of the linear actuator 1000. The screw 200 of the ball screw structure 10 can extend or retract into the housing 20 when the linear actuator 1000 is operating. The movement of the screw 200 can achieve a push-pull action, which not only reduces the assembly workload of the linear actuator structure, but also reasonably reduces the axial length of the actuator structure, enabling the linear actuator to better meet the linear actuation requirements in a small space.

[0067] Specifically, the housing 20 comprises a main housing 21, a front cover 22 secured to the front end of the main housing 21, and a rear cover 23 secured to the rear end of the main housing. The nut 100 is rotatably mounted within the housing 20 and axially positioned via two spaced-apart bearings. The front end of the screw 200 extends out of the housing 20 and is connected to a front connector 41. The rear cover 23 is connected to a rear connector 42. A stator module 30 is sleeved outside the central region of the nut 100 and positioned within the inner periphery of the housing 20. The stator module 30 can employ a conventional structure consisting of a stator core and stator windings. Furthermore, the housing 20 includes a support frame 24 clamped between the main housing 21 and the rear cover 23. The linear actuator 1000 also includes an encoder 50 located behind the support frame 24. A control board 60 is located within the rear end of the housing 20, behind the ball screw structure 10. The encoder 50 and control board 60 communicate with each other to ensure accurate operation of the linear actuator 10. In addition, an oil filling hole 25 is provided on the front wall or side wall of the housing 20. Lubricating oil or grease can be added to the interior of the linear actuator 1000 through the oil filling hole 25 after the linear actuator 1000 has been working for a period of time, so that the interior of the linear actuator 1000 is in a smooth transmission state, which is also convenient for regular maintenance of the linear actuator 1000.

[0068] During operation, the rear joint 42 of the linear actuator 1000 is hingedly or fixedly connected to another object, while the front joint 41 is connected to the object being actuated. When the linear actuator 1000 is in operation, switching the direction of current flowing through the stator module 30 changes the rotation direction of the nut 100, allowing the lead screw 200 to extend forward or retract backward, thereby enabling the actuated object to perform a corresponding action or execute a corresponding instruction.

[0069] Example 2

[0070] Combine Figure 10 、 Figure 11In this embodiment, after the ball 400 is installed in the receiving hole 511 , a limit block 523 is spot-welded on the outer hole wall 511 a of the receiving hole 511 , and the limit block 523 is used to form a second limit surface 522 .

[0071] As a specific solution of this embodiment, at least two limiting blocks 523 formed by spot welding are provided at intervals along the circumference of the receiving hole 511 .

[0072] The other structures of the ball screw structure are the same as those in the first embodiment and will not be described in detail here.

[0073] The other structures of the linear actuator except the ball screw structure are the same as those in the first embodiment and are not described in detail here.

[0074] Example 3

[0075] In this embodiment, the hole wall of the receiving hole is a cylindrical surface. Spot welding is first performed on the inner hole wall of the receiving hole to form a limiting protrusion, and the limiting protrusion is used to form a first limiting surface. Then, the ball is installed in the receiving hole, and the retaining frame is press-riveted to form a second limiting surface. Alternatively, spot welding is performed on the outer hole wall of the receiving hole to form a limiting block, and the limiting block is used to form a second limiting surface.

[0076] The other structures of the ball screw structure are the same as those in the first embodiment and will not be described in detail here.

[0077] The other structures of the linear actuator except the ball screw structure are the same as those in the first embodiment and are not described in detail here.

[0078] Example 4

[0079] Combine Figure 12a 、 Figure 12b In this embodiment, the receiving portion 510 is a receiving groove 512 provided on the retainer 500. Specifically, the receiving groove 512 extends continuously in a spiral from one end of the retainer 500 to the other end, and the helix angle of the receiving groove 512 is consistent with the helix angle of the raceway 300. In the initial state, the groove wall of the receiving groove 512 is inclined, and the inner groove width of the receiving groove 512 is smaller than the outer groove width. After the ball 400 is installed in the receiving groove 512, it is riveted, so that the outer groove wall of the receiving groove 512 forms a second limiting surface 522, and the inner groove wall of the receiving groove 512 forms a first limiting surface 521. The combination of the first limiting surface 521 and the second limiting surface 522 forms a bidirectional tapered groove structure, thereby retaining the ball 400 in the receiving groove 512.

[0080] As an alternative to this embodiment, after the ball 400 is installed in the receiving groove 512 , spot welding can be performed on the outer groove wall to form a limiting block, and the limiting block is used to form the second limiting surface 522 .

[0081] As an alternative to this embodiment, spot welding may be performed on the inner groove wall of the receiving groove 512 to form a limiting protrusion, and the limiting protrusion is used to form the first limiting surface 521.

[0082] Combine Figure 13 As an alternative to this embodiment, the receiving groove 512 can also be set in sections along the axial direction of the retaining frame 500, and the sectioned receiving grooves 512 are located on the same spiral.

[0083] The other structures of the ball screw structure are the same as those in the first embodiment and will not be described in detail here.

[0084] The other structures of the linear actuator except the ball screw structure are the same as those in the first embodiment and are not described in detail here.

[0085] In addition to the above preferred embodiments, the present invention has other implementation methods. Those skilled in the art can make various changes and modifications based on the present invention. As long as they do not depart from the spirit of the present invention, they should all fall within the scope defined in the claims of the present invention.

Claims

1. Ball screw structure with cage, including: The nut has a through hole and a first spiral groove provided on the wall of the through hole; A screw rod having a transmission portion cooperating with the nut, wherein a second spiral groove is provided on an outer circumference of the transmission portion; The first spiral groove and the second spiral groove cooperate to form a spiral raceway, at least a portion of the raceway has a plurality of balls distributed along the raceway, and the balls move along the raceway when the nut or the screw is braked; It is characterized in that the ball screw structure also includes a retaining frame arranged between the transmission part and the nut, the retaining frame is provided with a receiving portion for installing balls, the receiving portion extends spirally and is consistent with the spiral of the raceway, and the inner wall of the receiving portion is provided with a limiting structure for retaining the balls in the receiving portion. The balls moving along the raceway drive the retaining frame to move and the balls can rotate in the receiving portion.

2. The ball screw structure with a cage according to claim 1, characterized in that: The limiting structure includes a first limiting surface and a second limiting surface which are arranged on the inner wall of the receiving portion and distributed inside and outside. The first limiting surface and the second limiting surface are arranged at an obtuse angle. The minimum distance between the first limiting surface and the second limiting surface and the center line of the receiving portion respectively is less than the diameter of the ball.

3. The ball screw structure with a cage according to claim 2, characterized in that: The first limiting surface is directly formed on the inner wall of the receiving portion; or, the first limiting surface is formed by spot welding.

4. The ball screw structure with a cage according to claim 2, characterized in that: The second limiting surface is formed by riveting a portion of the inner wall of the receiving portion; or, the second limiting surface is formed by spot welding.

5. The ball screw structure with a cage according to claim 2, characterized in that: An included angle θ between the first limiting surface and the second limiting surface is 140° to 160°.

6. The ball screw structure with a cage according to any one of claims 1 to 5, characterized in that: The retaining frame is in a hollow cylindrical shape, and the receiving portion is a receiving hole provided on the retaining frame. A plurality of the receiving holes are provided at intervals along the same spiral track as the raceway.

7. The ball screw structure with a cage according to any one of claims 1 to 5, characterized in that: The retaining frame is in a hollow cylindrical shape, the receiving portion is a receiving groove provided on the retaining frame, and the receiving groove extends spirally.

8. The ball screw structure with a cage according to claim 7, characterized in that: The receiving grooves are continuously arranged and extend from one end to the other end of the retaining frame; or, the receiving grooves are spaced apart and are spaced apart in at least two sections along the axial direction of the retaining frame.

9. The ball screw structure with a cage according to claim 1, characterized in that: The inner diameter of the retaining frame is larger than the outer diameter of the transmission part, and the outer diameter of the retaining frame is smaller than the inner diameter of the through hole.

10. A linear actuator comprising a housing and a stator module, characterized in that: It also includes a ball screw structure with a retainer as described in any one of claims 1 to 9 above, the ball screw structure is arranged in the casing and the screw rod can extend out of the casing, the nut is axially positioned and rotatably mounted in the casing, and the stator module is axially positioned outside the nut.

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