Ball screw structure and linear actuator

Abstract

The utility model discloses a ball screw structure and linear actuator belongs to transmission structure technical field, ball screw structure includes nut, lead screw, nut has through hole and first spiral groove, lead screw has transmission portion and second spiral groove, first spiral groove and second spiral groove cooperate to form transmission raceway, in transmission raceway has a plurality of balls, and the transmission raceway is equipped with the first spiral groove and second spiral groove. The axial length of the nut is larger than that of the transmission part, the screw rod is further provided with a rod part and a return roller path, the transmission part is arranged outside the rod part in a sleeving mode, the return roller path comprises a main body section and a connecting section, and the main body section of the return roller path is arranged between the rod part and the transmission part; and the connecting section of the return raceway is arranged between the end part of the transmission raceway and the end part of the main body section, so that the transmission raceway and the main body section are smoothly communicated. Due to the fact that the return raceway is arranged on the lead screw, the outer diameter of the nut can be reasonably reduced while the outer diameter of the lead screw is not increased, the whole ball screw structure is more compact, and therefore the ball screw structure can better meet the transmission requirement of small precision machinery.

Description

Technical Field

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

[0002] A ball screw pair generally consists of a screw rod, a nut and a ball arranged between the two. A spiral groove for the ball to move is formed between the outer surface of the screw rod and the inner surface of the nut. The movement of the ball can convert rotational motion into linear motion, or convert linear motion into rotational motion.

[0003] During the operation of the ball screw pair, since the balls move unidirectionally in the spiral groove, in order to allow the balls that move to the end of the groove to return to the groove, a return raceway is generally provided on the nut. The two ends of the return raceway are respectively connected to the two ends of the groove. The balls that move to the end of the groove return to the starting end of the groove through the return raceway, thereby allowing the balls to circulate.

[0004] When the axial length of the nut is greater than the axial length of the external thread on the screw, if the return raceway is still set on the nut, the internal thread on the nut cannot fully engage with the external thread on the screw and the ball will fall out of the return raceway. The fallen balls will not only be unable to return to the raceway to participate in the transmission, but will also interfere with the transmission between the nut and the screw, which is not conducive to ensuring the transmission stability of the structure. Utility Model Content

[0005] In order to solve the shortcomings and deficiencies in the above-mentioned prior art, the utility model provides a ball screw structure, in which the return raceway is arranged on the screw, which can reasonably reduce the outer diameter of the nut without increasing the outer diameter of the screw, making the overall ball screw structure more compact, so that the ball screw structure can better meet the transmission requirements of small precision machinery.

[0006] In order to achieve the above technical objectives, the ball screw structure provided by the present invention includes:

[0007] The nut has a through hole and a first spiral groove provided on the wall of the through hole;

[0008] The screw has a transmission portion rotatably disposed in the nut, and a second spiral groove is provided on the outer circumference of the transmission portion;

[0009] The first spiral groove cooperates with the second spiral groove to form a spiral transmission raceway, wherein a plurality of balls are arranged in the transmission raceway, and the balls move along the transmission raceway when the nut or the lead screw is actuated;

[0010] The axial length of the nut is greater than the axial length of the transmission part. The screw rod is also provided with a rod part and a return raceway. The transmission part is sleeved on the outside of the rod part. The return raceway is used to guide the balls that move to one end of the transmission raceway back to the other end of the transmission raceway. The return raceway includes a main section and a connecting section. The main section is provided between the rod part and the transmission part, and the connecting section is provided between the end of the transmission raceway and the end of the main section to connect the two smoothly.

[0011] Preferably, the main body section of the return raceway extends along the axial direction of the screw rod; or, the main body section of the return raceway extends in a spiral shape around the central axis of the screw rod.

[0012] Preferably, the transmission part is provided with an axial hole that cooperates with the rod part, a groove is provided on the outer peripheral surface of the rod part, and the main section is formed by the cooperation of the groove and the hole wall of the axial hole; or, the transmission part is provided with an axial hole that cooperates with the rod part, a groove is provided on the hole wall of the axial hole, and the main section is formed by the cooperation of the groove and the outer peripheral surface of the rod part; or, the transmission part is provided with an axial hole that cooperates with the rod part, a first groove body is provided on the outer peripheral surface of the rod part, a second groove body is provided on the hole wall of the axial hole, and the main section is formed by the cooperation of the first groove body and the second groove body.

[0013] Preferably, one end of the connecting section facing the transmission raceway is tangent to the end of the transmission raceway.

[0014] Preferably, the connecting section includes a first portion provided on the outer circumferential surface of the rod portion and a second portion provided on the transmission portion, the first portion is connected to the end of the main section, and the second portion is connected to the end of the second spiral groove.

[0015] Preferably, the screw rod is also provided with a return block, at least one end of the transmission part is provided with a notch that cooperates with the return block, the return block is arranged at the notch, and the connecting section of the return raceway is arranged on the return block or between the return block and the transmission part.

[0016] Preferably, the end surface of the return block perpendicular to the axial direction of the screw rod is in a fan ring shape.

[0017] Preferably, an insertion hole communicating with the second spiral groove is provided on the end surface of the transmission part, and the ball is inserted through the insertion hole.

[0018] Preferably, the axial length of the first spiral groove is 1.5 to 5 times the axial length of the second spiral groove.

[0019] The present invention also provides a linear actuator, including a housing, a stator module and the ball screw structure described above. The ball screw structure is arranged in the housing and the rod portion of the screw 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.

[0020] After adopting the above technical solution, the utility model has the following advantages:

[0021] 1. The ball screw structure provided by the present invention has a return raceway disposed on the screw, a main section of the return raceway disposed between the rod and the transmission portion, a connecting section of the return raceway disposed between the end of the transmission raceway and the end of the main section, and both ends of the return raceway are smoothly connected to the transmission raceway via the connecting section. The balls that move to the end of the transmission raceway pass through the return raceway and return to the transmission raceway, so that the balls can circulate. Since the main section of the return raceway is disposed on the screw, when the axial length of the nut is greater than the axial length of the transmission portion on the screw, the balls that pass through the return raceway can smoothly return to the transmission raceway, avoiding the situation where the balls that pass through the return raceway cannot re-enter the transmission raceway due to the return raceway being disposed on the nut and fall out. This improves the structural stability of the balls and prevents the fallen balls from interfering with the transmission coordination between the screw and the nut, thereby ensuring the transmission stability of the entire ball screw structure. In addition, since the return raceway is arranged on the screw, the outer diameter of the nut can be reasonably reduced without increasing the outer diameter of the screw, making the overall ball screw structure more compact, so that the ball screw structure can better meet the transmission requirements of small precision machinery.

[0022] 2. The main section of the return raceway can extend along the axial direction of the screw rod or extend spirally around the central axis of the screw rod. The extension direction of the main section is reasonably set so that the ball can move axially relative to the screw rod in the main section, so that the ball can move from one end of the transmission raceway to the other end through the return raceway, and then the ball can return to the transmission raceway.

[0023] 3. The main section of the return raceway can be formed by the groove on the outer peripheral surface of the rod and the hole wall of the shaft hole on the transmission part, or by the groove on the hole wall of the shaft hole and the outer peripheral surface of the rod, or by the first groove on the outer peripheral surface of the rod and the second groove on the hole wall of the shaft hole. The specific structure of the main section is reasonably set so that the main section can be completely located between the rod and the transmission part.

[0024] 4. The end of the connecting section facing the transmission raceway is tangent to the end of the transmission raceway, allowing the balls that move to the end of the transmission raceway to pass through the connecting section and enter the return raceway smoothly, and also allowing the balls that pass through the return raceway to enter the transmission raceway smoothly. Reasonable connection between the connecting section and the transmission raceway improves the smoothness of the ball's circulation between the transmission raceway and the return raceway.

[0025] 5. The connecting section of the return raceway can be formed by the first part on the outer peripheral surface of the rod and the second part on the transmission part. The first part is connected to the end of the main section, and the second part is connected to the end of the second spiral groove. The formation method of the connecting section is reasonably set so that the connecting section can smoothly connect the main section and the transmission raceway.

[0026] 6. A return block can be set on the screw rod, and the return block is set at the notch at the end of the transmission part. The connecting section can be set on the return block, or the connecting section can be set between the return block and the transmission part. The formation method of the connecting section is reasonably set, and the processing difficulty of the connecting section can be reasonably reduced through the return block.

[0027] 7. The end face of the return block is preferably arranged to be fan-shaped, that is, the return block is roughly in the shape of a fan-shaped block. The return block can be installed at the opening at the end of the transmission part not only axially, but also radially, which is conducive to reasonably reducing the difficulty of installing the return block.

[0028] 8. A loading hole is provided on the end face of the transmission part, which is connected to the second spiral groove. The balls can be inserted into the transmission raceway through the loading hole. When the transmission raceway is filled, the newly inserted balls can squeeze the balls in the transmission raceway into the return raceway, thereby realizing the installation of the balls and preventing the installed balls from falling out of the transmission raceway.

[0029] 9. The linear actuator provided by the present invention adopts the ball screw structure described above. The ball screw structure directly serves 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 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

[0030] Figure 1 This is an overall diagram of the ball screw structure of Example 1;

[0031] Figure 2 This is an axial cross-sectional view of the ball screw structure of Example 1;

[0032] Figure 3 This is a structural diagram of the nut in the ball screw structure of Example 1;

[0033] Figure 4 This is an axial cross-sectional view of the nut in the ball screw structure of Example 1;

[0034] Figure 5 This is a partial structural diagram of the ball screw structure in Example 1;

[0035] Figure 6 An exploded view of the rod portion and the transmission portion of the ball screw structure in Example 1;

[0036] Figure 7 This is a structural diagram of the transmission part in the ball screw structure of Example 1;

[0037] Figure 8 This is a partial structural diagram of the rod portion of the ball screw structure in Example 1;

[0038] Figure 9 is an axial cross-sectional view of the linear actuator of Example 1;

[0039] Figure 10 This is the partial structure of the screw in the ball screw structure of Example 5;

[0040] Figure 11 An exploded view of the screw in the ball screw structure of Example 5;

[0041] Figure 12 This is a partial structural diagram of the rod portion in the ball screw structure of Example 5;

[0042] Figure 13 This is a structural diagram of the transmission part in the ball screw structure of Example 5;

[0043] Figure 14 This is a structural diagram of the return block in the ball screw structure of Example 5;

[0044] Figure 15 This is an exploded view of the screw rod in the ball screw structure of Example 6.

[0045] In the figure, 100-ball screw structure,

[0046] 110-nut, 111-through hole, 112-first spiral groove,

[0047] 120-screw, 121-transmission part, 1211-shaft hole, 1212-notch, 122-second spiral groove, 123-rod, 1231-groove, 124-return raceway, 1241-main section, 1242-connecting section, 1242a-first part, 1242b-second part, 125-loading hole, 126-return block,

[0048] 130- transmission roller,

[0049] 140-ball,

[0050] 10-Linear actuator, 200-Casing, 210-Main housing, 220-Front cover, 230-Rear cover, 240-Support bracket, 250-Oil filling hole, 300-Stator module, 410-Front connector, 420-Rear connector, 500-Encoder, 600-Control board. DETAILED DESCRIPTION

[0051] 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.

[0052] Example 1

[0053] Combine Figures 1 to 8 The ball screw structure 100 provided in the first embodiment of the present invention includes:

[0054] The nut 110 has a through hole 111 and a first spiral groove 112 provided on the wall of the through hole 111;

[0055] The screw rod 120 has a transmission portion 121 rotatably disposed in the nut 110 , and a second spiral groove 122 is provided on the outer circumference of the transmission portion 121 ;

[0056] The first spiral groove 112 cooperates with the second spiral groove 122 to form a spiral transmission track 130. The transmission track 130 has a plurality of balls 140 therein. The balls 140 move along the transmission track 130 when the nut 110 or the screw rod 120 is actuated.

[0057] The axial length L1 of the nut 110 is greater than the axial length L2 of the transmission part 121. The screw rod 120 also has a rod portion 123 and a return raceway 124. The transmission part 121 is sleeved on the outside of the rod portion 123. The return raceway 124 is used to guide the balls 140 that move to one end of the transmission raceway 130 back to the other end of the transmission raceway 130. The return raceway 124 includes a main section 1241 and a connecting section 1242. The main section 1241 of the return raceway 124 is arranged between the rod portion 123 and the transmission part 121, and the connecting section 1242 of the return raceway 124 is arranged between the end of the transmission raceway 130 and the end of the main section 1241 to connect the two smoothly.

[0058] Because the main section 1241 of the return raceway 124 is provided on the screw rod 120, when the axial length of the nut 110 is greater than the axial length of the transmission portion 121, the balls 140 passing through the return raceway 124 can smoothly return to the transmission raceway 130 to participate in the transmission, thereby preventing the balls 140 passing through the return raceway from being unable to re-enter the transmission raceway 130 due to the return raceway 124 being provided on the nut 110 and falling out. This improves the structural stability of the balls 140 and prevents the fallen balls 140 from interfering with the transmission coordination between the screw rod 120 and the nut 110, thereby ensuring the overall transmission stability of the ball screw structure 100. In addition, because the return raceway 124 is provided on the screw rod 120, the outer diameter of the nut 110 can be reasonably reduced without increasing the outer diameter of the screw rod 120, making the ball screw structure 100 more compact as a whole, thereby enabling the ball screw structure 100 to better meet the transmission requirements of small precision machinery.

[0059] In this embodiment, the inner diameter of the through hole 111 is slightly larger than the outer diameter of the transmission part 121 to avoid friction caused by contact between the hole wall of the through hole 111 and the outer peripheral surface of the transmission part 121 during relative movement, so that the nut 110 and the screw rod 120 can move smoothly relative to each other. The spiral directions of the first spiral groove 112 and the second spiral groove 122 are consistent, and the groove depth and groove width of the first spiral groove 112 and the second spiral groove 122 are also basically consistent. The depth of the transmission raceway 130 formed by the first spiral groove 112 and the second spiral groove 122 is basically consistent with the outer diameter of the ball 140. The ball 140 rotates while performing spiral movement along the transmission raceway 130. As a further solution of this embodiment, for the nut 110 with a larger axial length L1, in order to reduce the difficulty of processing the first spiral groove 112 on the hole wall of the through hole 111, the nut 110 can adopt a multi-stage combination structure.

[0060] In this embodiment, the axial length of the first helical groove 112 is substantially consistent with the axial length L1 of the nut 110, and the axial length of the second helical groove 122 is substantially consistent with the axial length L2 of the transmission portion 121. Since the axial length L1 of the nut 110 is greater than the axial length L2 of the transmission portion 121, the axial length of the first helical groove 112 is greater than the axial length of the second helical groove 122. In this embodiment, the nut 110 is actuated as the active element, and the screw rod 120 is the passive element. When the nut 110 is actuated, the nut 110 rotates about its own central axis. The rotating nut 110 drives the screw rod 120 to move axially via the ball bearings 140, thereby achieving extension and retraction of the screw rod 120. For example, when the nut 110 is actuated to rotate forward, the balls 140 move from back to front within the transmission raceway 130, causing the screw 120 to extend relative to the nut 110. When the nut 110 is actuated to rotate backward, the balls 140 move from front to back within the transmission raceway 130, causing the screw 120 to retract relative to the nut 110. In order to ensure that the screw 120 meets the required telescopic distance while reasonably controlling the axial length of the nut 110, the axial length of the first helical groove 112 is preferably set to 1.5 to 5 times the axial length of the second helical groove 122. That is, the axial length L1 of the nut 110 is preferably set to 1.5 to 5 times the axial length L2 of the transmission portion 121. Specifically, the axial length L1 of the nut 110 can be a reasonable value such as 1.5 times, 2 times, 2.5 times, 3 times, 3.5 times, 4 times, 4.5 times, or 5 times the axial length L2 of the transmission portion 121. The second spiral groove 122 can be set to a reasonable number of turns such as 2 turns, 3 turns, 4 turns, 5 turns, 6 turns, 7 turns, 8 turns, 9 turns, or 10 turns. Of course, the axial length L1 of the nut 110 can also be set to other reasonable values such as 5.5 times, 6 times, 6.5 times, 7 times, 7.5 times, or 8 times the axial length L2 of the transmission portion 121.

[0061] The transmission portion 121 is provided with an axially extending shaft hole 1211. The transmission portion 121 is sleeved onto the exterior of the rear end of the rod portion 123 through the cooperation of the shaft hole 1211 and the rod portion 123. In this embodiment, a groove 1231 is provided on the outer circumferential surface of the rear end of the rod portion 123. When the transmission portion 121 is sleeved onto the exterior of the rear end of the rod portion 123, the groove 1231 cooperates with the wall of the shaft hole 1211 to form the main body section 1241 of the return raceway 124. Specifically, in this embodiment, the groove 1231 extends axially along the rod portion 123 and is in the shape of an elongated strip. Accordingly, the main body section 1241 is in the shape of an elongated strip extending axially along the rod portion 123. This appropriately shortens the path length of the ball 140 moving within the return raceway 124.

[0062] A connecting segment 1242 is provided at each end of the return raceway 124. The connecting segment 1242 includes a first portion 1242a provided on the outer circumference of the rod portion 123 and a second portion 1242b provided on the transmission portion 121. The first portion 1242a communicates with the end of the main segment 1241, while the second portion 1242b communicates with the end of the second spiral groove 122. The second portion 1242b extends from the inner surface of the transmission portion 121 to the outer surface of the transmission portion 121. The connecting segment 1242 formed by the combination of the first and second portions 1242a, 1242b, is generally involute-shaped relative to the central axis of the lead screw 120. Specifically, the distance between the connecting segment 1242 and the central axis of the lead screw 120 gradually increases from the end connected to the main segment 1241 to the end connected to the transmission raceway 130, allowing the connecting segment 1242 to smoothly connect the ends of the main segment 1241 and the transmission raceway 130. Furthermore, in order to allow the ball 140 passing through the connecting section 1242 to return smoothly to the transmission raceway 130, the end of the connecting section 1242 facing the transmission raceway 130 is preferably arranged tangent to the end of the transmission raceway 130, that is, the tangential direction of the connecting section 1242 close to the end of the transmission raceway 130 is preferably roughly consistent with the tangential direction of the end of the transmission raceway 130.

[0063] In order to install the ball 140, an installation hole 125 is provided on one end surface of the transmission part 121. The installation hole 125 is connected to the second spiral groove 122, and the ball 140 can be inserted into the transmission raceway 130 and the return raceway 124 through the installation hole 125. During assembly, the transmission part 121 is first sleeved on the end of the rod part 123, the groove 1231 cooperates with the hole wall of the shaft hole 1211 to form the main section 1241, the first part 1242a cooperates with the second part 1242b to form the connecting section 1242, and then the nut 110 is sleeved on the outside of the transmission part 121, the first spiral groove 112 is aligned with the second spiral groove 122 to form a transmission raceway 130, and then the balls 140 are inserted one by one from the loading hole 125. The inserted balls 140 first fill the transmission raceway 130, and the balls 140 inserted later can squeeze the balls 140 in the transmission raceway 130 into the return raceway 124. When the return raceway 124 and the transmission raceway 130 are filled with balls 140, the assembly of the ball screw structure 100 is completed.

[0064] Combine Figure 9This embodiment further provides a linear actuator 10, comprising a housing 200, a stator module 300, and the aforementioned ball screw structure 100. The ball screw structure 100 is disposed within the housing 200, and the rod portion 123 of the screw 120 can extend out of the housing 200. The nut 110 is axially positioned and rotatably mounted within the housing 200, and the stator module 300 is axially positioned and sleeved on the exterior of the nut 110. The ball screw structure 100 is directly used as the rotor module of the linear actuator. The screw 120 of the ball screw structure 100 can extend or retract into the housing 200 when the linear actuator 10 is operating. The movement of the screw 120 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.

[0065] Specifically, the housing 200 includes a main housing 210, a front cover 220 fixed to the front end of the main housing 210, and a rear cover 230 fixed to the rear end of the main housing 210. The nut 110 is rotatably mounted within the housing 200 and axially positioned via two spaced-apart bearings. The front end of the screw rod 120 extends out of the housing 200 and is connected to a front connector 410. The rear cover 230 is connected to a rear connector 420. The stator module 300 is sleeved outside the central area of the nut 110 and is located on the inner circumference of the housing 200. The stator module 300 can adopt a conventional structure consisting of a stator core and stator windings. The housing 200 also includes a support bracket 240 clamped between the main housing 210 and the rear cover 230. The linear actuator 10 also includes an encoder 500 located behind the support bracket 240. A control board 600 is located within the rear end of the housing 200, behind the ball screw structure 100. The encoder 500 and the control board 600 can communicate with each other to ensure the precise operation of the linear actuator 10. Furthermore, an oil filling port 250 is provided on the front or side wall of the housing 200. This port allows lubricating oil or grease to be added to the interior of the linear actuator 10 after a period of operation. This ensures smooth transmission within the linear actuator 10 and facilitates regular maintenance of the linear actuator 10.

[0066] During operation, the rear joint 420 of the linear actuator 10 is hingedly or fixedly connected to another object, while the front joint 410 is connected to the object being actuated. When the linear actuator 10 is in operation, switching the direction of current flowing through the stator module 300 changes the rotation direction of the nut 110, allowing the lead screw 120 to extend forward or retract backward, thereby enabling the actuated object to perform a corresponding action or execute a corresponding instruction.

[0067] Example 2

[0068] In this embodiment, the main section of the return raceway adopts a spiral structure. In this case, the groove on the outer surface of the rod extends spirally around the central axis of the rod. Accordingly, the main section, formed by the groove and the wall of the axial hole, also extends spirally around the central axis of the rod. This increases the path length of the main section and the number of balls within it, which can appropriately increase the load capacity of the entire structure.

[0069] 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.

[0070] 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.

[0071] Example 3

[0072] In this embodiment, the groove is provided on the wall of the shaft hole. When the transmission part is sleeved on the end of the rod, the groove on the wall of the shaft hole cooperates with the outer peripheral surface of the rod to form the main section of the return raceway.

[0073] The main body section in this embodiment can be configured as a long strip extending along the axial direction of the screw rod as in the first embodiment, or can be configured as a spiral extending around the central axis of the screw rod as in the second embodiment.

[0074] 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.

[0075] 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.

[0076] Example 4

[0077] In this embodiment, a first groove body is provided on the outer surface of the rod portion, and a second groove body is provided on the hole wall of the shaft hole. When the transmission part is sleeved on the end of the rod portion, the first groove body and the second groove body cooperate to form the main section of the return raceway.

[0078] The main body section in this embodiment can be configured as a long strip extending along the axial direction of the screw rod as in the first embodiment, or can be configured as a spiral extending around the central axis of the screw rod as in the second embodiment.

[0079] 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.

[0080] 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.

[0081] Example 5

[0082] Combine Figures 10 to 14In this embodiment, the screw rod 120 further includes a return block 126. A notch 1212 is provided at at least one end of the transmission portion 121 to mate with the return block 126. The return block 126 is positioned at the notch 1212, and the connecting section 1242 of the return raceway 124 is positioned on the return block 126. Specifically, the notch 1212 is provided at both ends of the transmission portion 121. The notch 1212 extends axially from the end surface of the transmission portion 121 to a certain depth. The cross-section of the notch 1212 perpendicular to the axial direction of the screw rod 120 is fan-shaped. The groove walls and bottom wall of the notch 1212 are both flat, and the notch 1212 radially penetrates the transmission portion 121. Accordingly, the end surface of the return block 126 is fan-shaped, with both sidewalls and end surface being flat. The return block 126 can be installed radially or axially at the notch 1212. The connecting section 1242 is completely arranged on the return block 126, and the connecting section 1242 extends from the inner surface to the outer surface of the return block 126, that is, the connecting section 1242 is arranged through the return block 126, one end of the connecting section 1242 is connected to the end of the main body section 1241, and the other end of the connecting section 1242 is connected to the end of the second spiral groove 122. The connecting section 1242 is roughly in the shape of an involute relative to the central axis of the screw rod 120, that is, the distance between the connecting section 1242 and the central axis of the screw rod 120 gradually increases from the end connected to the main body section 1241 to the end connected to the second spiral groove 122.

[0083] The main body section in this embodiment can be configured as a long strip extending along the axial direction of the screw rod 120 in the first embodiment, or can be configured as a spiral extending around the central axis of the screw rod 120 in the second embodiment.

[0084] In this embodiment, the loading hole 125 can be provided on the return block 126 or on the transmission part 121 .

[0085] As an alternative to this embodiment, a return block 126 may be provided at only one end of the transmission portion 121 , with the connecting section 1242 at one end of the return raceway 124 provided on the return block 126 , and the connecting section 1242 at the other end of the return raceway 124 adopting the structure of the first embodiment.

[0086] 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.

[0087] 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.

[0088] Example 6

[0089] Combine Figure 15In this embodiment, the connecting section is provided between the return block 126 and the transmission part 121. Specifically, a notch is provided on the return block 126. When the return block 126 is installed at the notch 1212 on the transmission part 121, the notch on the return block 126 cooperates with the partial second spiral groove 122 on the transmission part 121 to form the connecting section of the return raceway.

[0090] The main body section in this embodiment can be configured as a long strip extending along the axial direction of the screw rod 120 in the first embodiment, or can be configured as a spiral extending around the central axis of the screw rod 120 in the second embodiment.

[0091] In this embodiment, the loading hole 125 can be provided on the return block 126 or on the transmission part 121 .

[0092] As an alternative to this embodiment, a return block 126 may be provided at only one end of the transmission portion 121 , with the connecting section at one end of the return raceway being provided on the return block 126 , and the connecting section at the other end of the return raceway adopting the structure of the first embodiment.

[0093] 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.

[0094] 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.

[0095] 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, including: The nut has a through hole and a first spiral groove provided on the wall of the through hole; The screw has a transmission portion rotatably disposed in the nut, and a second spiral groove is provided on the outer circumference of the transmission portion; The first spiral groove cooperates with the second spiral groove to form a spiral transmission raceway, wherein a plurality of balls are arranged in the transmission raceway, and the balls move along the transmission raceway when the nut or the lead screw is actuated; It is characterized in that the axial length of the nut is greater than the axial length of the transmission part, the screw rod is also provided with a rod part and a return raceway, the transmission part is sleeved on the outside of the rod part, the return raceway is used to guide the balls that move to one end of the transmission raceway back to the other end of the transmission raceway, and the return raceway includes a main section and a connecting section, the main section is provided between the rod part and the transmission part, and the connecting section is provided between the end of the transmission raceway and the end of the main section and the two are smoothly connected.

2. The ball screw structure according to claim 1, characterized in that: The main body section of the return raceway extends along the axial direction of the screw rod; or the main body section of the return raceway extends in a spiral shape around the central axis of the screw rod.

3. The ball screw structure according to claim 1, characterized in that: The transmission part is provided with an axial hole that cooperates with the rod part, and a groove is provided on the outer peripheral surface of the rod part, and the main section is formed by the groove and the hole wall of the axial hole; or, the transmission part is provided with an axial hole that cooperates with the rod part, and a groove is provided on the hole wall of the axial hole, and the main section is formed by the groove and the outer peripheral surface of the rod part; or, the transmission part is provided with an axial hole that cooperates with the rod part, a first groove body is provided on the outer peripheral surface of the rod part, and a second groove body is provided on the hole wall of the axial hole, and the main section is formed by the first groove body and the second groove body.

4. The ball screw structure according to claim 1, characterized in that: One end of the connecting section facing the transmission raceway is tangent to the end of the transmission raceway.

5. The ball screw structure according to any one of claims 1 to 4, characterized in that: The connecting section includes a first part provided on the outer circumference of the rod and a second part provided on the transmission part. The first part is connected to the end of the main section, and the second part is connected to the end of the second spiral groove.

6. The ball screw structure according to any one of claims 1 to 4, characterized in that: The screw rod is also provided with a return block, at least one end of the transmission part is provided with a notch that matches the return block, the return block is arranged at the notch, and the connecting section of the return raceway is arranged on the return block or between the return block and the transmission part.

7. The ball screw structure according to claim 6, characterized in that: The end surface of the return block perpendicular to the axial direction of the screw rod is in a fan-shaped shape.

8. The ball screw structure according to claim 1, characterized in that: An insertion hole communicating with the second spiral groove is provided on the end surface of the transmission part, and the ball is inserted through the insertion hole.

9. The ball screw structure according to claim 1, characterized in that: The axial length of the first spiral groove is 1.5 to 5 times the axial length of the second spiral groove.

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

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