A linear actuator

Abstract

This utility model relates to the field of mechanical transmission technology, specifically disclosing a linear actuator. The linear actuator includes a mounting base, a motor, a worm gear, a worm wheel, a main nut, a lead screw, a first bearing, and a second bearing. The motor is mounted on the mounting base, the worm gear is driven by the motor, the worm wheel meshes with the worm gear, the main nut is driven by the worm wheel, and the lead screw is threadedly connected to the main nut. The outer ring of the first bearing is fixedly mounted on the mounting base, and the inner ring of the first bearing is fixedly sleeved on the worm gear. The second bearing is located away from the motor relative to the first bearing. The outer ring of the second bearing is fixedly mounted on the mounting base, and the inner ring of the second bearing is sleeved on the worm gear, allowing the worm gear to slide axially relative to the inner ring of the second bearing. Because the worm gear and the second bearing can slide relative to each other, when the worm gear heats up and expands, causing its axial dimension to increase, the worm gear has a certain deformation space, releasing the axial deformation and preventing damage to the worm gear.

Description

Technical Field

[0001] This utility model relates to the field of mechanical transmission technology, and in particular to a linear actuator. Background Technology

[0002] Linear actuators are widely used in automation, medical, and military industries. Existing technology provides a linear actuator including a motor, worm gear, worm, main nut, sleeve, and lead screw. The motor is driven by the worm gear, the worm gear meshes with the worm and is fixedly connected to the sleeve, the main nut is fixedly installed on the sleeve and threadedly connected to the lead screw, and the lead screw is connected to an external actuator through a connector. When the motor starts, it drives the sleeve to rotate via the worm and worm gear, and the sleeve drives the main nut to rotate synchronously. Driven by the main nut, the lead screw can drive the external actuator to reciprocate. The worm is mounted on a mounting base via two bearings, with the worm abutting axially against each bearing. However, during use, the worm heats up, increasing its temperature, which leads to an increase in its axial dimension. Due to the bearing constraints, the worm lacks expansion space, making it prone to damage and affecting the lifespan of the linear actuator. Utility Model Content

[0003] The purpose of this invention is to provide a linear actuator to prevent the worm gear from being damaged due to thermal expansion.

[0004] This utility model provides a linear actuator, which includes a mounting base, a motor mounted on the mounting base, a worm gear drivenly connected to the motor, a worm wheel meshing with the worm gear, a main nut drivenly connected to the worm wheel, and a lead screw threadedly connected to the main nut. The linear actuator further includes:

[0005] The first bearing has its outer ring fixedly mounted on the mounting base and its inner ring fixedly sleeved on the worm gear.

[0006] The second bearing is located away from the motor relative to the first bearing. The outer ring of the second bearing is fixedly mounted on the mounting base, and the inner ring of the second bearing is sleeved on the worm gear. The worm gear can slide axially relative to the inner ring of the second bearing along the worm gear.

[0007] As a preferred technical solution for the linear actuator, the linear actuator further includes a sleeve, which is rotatably connected to the mounting base through multiple load-bearing bearings. The lead screw passes through the sleeve, and the worm gear and the main nut are both fixedly installed on the sleeve, with the worm gear and the main nut arranged coaxially.

[0008] As a preferred technical solution for the linear actuator, the linear actuator further includes a flat key, the main nut is provided with a keyway, the sleeve is provided with a keyhole, and the flat key is respectively inserted into the keyway and the keyhole;

[0009] The inner wall of the flat key and the keyway is filled with adhesive, and / or the inner wall of the flat key and the keyhole is filled with adhesive.

[0010] As a preferred technical solution for the linear actuator, the linear actuator further includes a bushing. Along the axial direction of the sleeve, the bushing is located between the main nut and the worm gear. The bushing is fixedly disposed on the sleeve. The lead screw passes through the bushing and is slidably connected to the bushing.

[0011] As a preferred embodiment of the linear actuator, the linear actuator includes a plurality of bushings, which are arranged sequentially along the axial direction of the sleeve; and / or,

[0012] The bushing is made of a self-lubricating material.

[0013] As a preferred technical solution for the linear actuator, the linear actuator further includes a safety nut, which is fixedly disposed on the sleeve and sleeved on the lead screw. The safety nut is configured to abut or separate from the lead screw along the axial direction of the lead screw.

[0014] As a preferred technical solution for the linear actuator, the plurality of load-bearing bearings include needle roller bearings and two thrust bearings respectively disposed on both sides of the needle roller bearings along the axial direction of the sleeve, wherein the needle roller bearings and the two thrust bearings are all located between the worm and the main nut.

[0015] As a preferred technical solution for the linear actuator, the plurality of load-bearing bearings further include deep groove ball bearings. Along the axial direction of the sleeve, the deep groove ball bearings and the needle roller bearings are respectively located on both sides of the worm gear, and the outer ring of the deep groove ball bearing is fixedly disposed on the mounting seat, while the inner ring of the deep groove ball bearing is slidably sleeved on the sleeve.

[0016] As a preferred technical solution for the linear actuator, a slot is provided at one end of the worm gear near the motor, the output shaft of the motor is inserted into the slot, and the output shaft of the motor is fixedly connected to the worm gear.

[0017] As a preferred technical solution for the linear actuator, the end of the worm gear away from the motor is provided with a first insertion part, which is exposed outside the mounting base and is used to insert with the second insertion part of the wrench.

[0018] The linear actuator provided by this utility model has at least the following beneficial effects:

[0019] This linear actuator includes a mounting base, a motor, a worm gear, a worm wheel, a main nut, a lead screw, a first bearing, and a second bearing. The motor is mounted on the mounting base, the worm gear is driven by the motor, the worm wheel meshes with the worm gear, the main nut is driven by the worm wheel, and the lead screw is threadedly connected to the main nut. The outer ring of the first bearing is fixedly mounted on the mounting base, and the inner ring of the first bearing is fixedly fitted onto the worm gear. The second bearing is located away from the motor relative to the first bearing. The outer ring of the second bearing is fixedly mounted on the mounting base, and the inner ring of the second bearing is fitted onto the worm gear, allowing the worm gear to slide axially relative to the inner ring of the second bearing. Because the worm gear and the second bearing can slide relative to each other, when the worm gear heats up and expands, causing its axial dimension to increase, the worm gear has a certain deformation space, releasing the axial deformation of the worm gear and thus preventing damage to the worm gear. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the linear actuator in an embodiment of the present invention;

[0021] Figure 2 This is a first cross-sectional view of the linear actuator in an embodiment of the present invention;

[0022] Figure 3 This is a second cross-sectional view of the linear actuator in an embodiment of the present invention;

[0023] Figure 4 This is a partial structural diagram of the linear actuator in an embodiment of the present invention.

[0024] In the picture:

[0025] 1. Mounting bracket;

[0026] 2. Motor; 21. Output shaft;

[0027] 3. Worm gear; 31. Slot; 32. First insertion part;

[0028] 4. Worm gear; 5. Main nut; 6. Lead screw; 7. First bearing; 8. Second bearing; 9. Connecting parts;

[0029] 10. Sleeve; 101. Keyhole;

[0030] 11. Flat key; 12. Bushing; 13. Safety nut; 14. Needle roller bearing; 15. Thrust bearing; 16. Deep groove ball bearing. Detailed Implementation

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] In existing linear actuators, when the motor starts, the motor drives the sleeve to rotate via the worm and worm wheel. The sleeve then drives the main nut to rotate synchronously. Driven by the main nut, the lead screw can drive the external actuator to reciprocate. The worm is mounted on the mounting base via two bearings, and the worm abuts against the two bearings axially. However, during use, the worm will heat up and its temperature will rise, which will cause the axial dimension of the worm to increase. However, due to the limitation of the bearings, the worm lacks the space for expansion, which makes the worm easily damaged and thus affects the service life of the linear actuator.

[0036] For this, please refer to Figures 1 to 4 This embodiment provides a linear actuator, which includes a mounting base 1, a motor 2, a worm gear 3, a worm wheel 4, a main nut 5, a lead screw 6, a first bearing 7, and a second bearing 8. The motor 2 is mounted on the mounting base 1, the worm gear 3 is driven by the motor 2, the worm wheel 4 meshes with the worm gear 3, the main nut 5 is driven by the worm wheel 4, and the lead screw 6 is threadedly connected to the main nut 5. The outer ring of the first bearing 7 is fixedly mounted on the mounting base 1, and the inner ring of the first bearing 7 is fixedly sleeved on the worm gear 3. The second bearing 8 is located away from the motor 2 relative to the first bearing 7. The outer ring of the second bearing 8 is fixedly mounted on the mounting base 1, and the inner ring of the second bearing 8 is sleeved on the worm gear 3, allowing the worm gear 3 to slide axially relative to the inner ring of the second bearing 8. In this configuration, the worm 3 is rotatably connected to the mounting base 1 via the first bearing 7 and the second bearing 8. The motor 2 can drive the worm 3 to rotate, which in turn drives the worm wheel 4 to rotate. The worm wheel 4 transmits power to the main nut 5, driving it to rotate. The main nut 5 drives the lead screw 6 to reciprocate, which in turn drives the external actuators. When the worm 3 heats up and expands, causing its axial dimension to increase, the worm 3 has a certain deformation space because the worm 3 and the second bearing 8 can slide relative to each other. This space can release the axial deformation of the worm 3 and prevent damage.

[0037] Specifically, in this embodiment, the worm 3 is provided with a first shoulder and a second shoulder. The first shoulder abuts against the inner ring of the first bearing 7 along the axial direction of the worm 3, and the second shoulder is spaced apart from the inner ring of the second bearing 8 along the axial direction of the worm 3. Specifically, the inner ring of the first bearing 7 is fixed by the first shoulder and a retaining ring, and the outer ring of the first bearing 7 is fixed by a boss and a bearing cap provided on the mounting base 1. The external force borne by the lead screw 6 is converted into the axial force borne by the worm 3 through the worm wheel 4. The axial force borne by the worm 3 can be either tensile or thrust. Since the second shoulder and the inner ring of the second bearing 8 are spaced apart along the axial direction of the worm 3, and the worm 3 can move relative to the second bearing 8 along the axial direction of the worm 3, the axial force borne by the worm 3 will ultimately be borne by the first bearing 7. This not only protects the worm 3 when it overheats, but also avoids the problem of dimensional chain out-of-gauge due to machining errors.

[0038] Alternatively, please continue to refer to Figure 1 The linear actuator also includes a connector 9 fixedly connected to the lead screw 6. The connector 9 is used for pivotal connection with a movable external actuator, and the mounting base 1 is used for fixing it to an external device. It should be noted that when the main nut 5 rotates, under the constraint of the external actuator, the lead screw 6 cannot rotate synchronously with the main nut 5, thus allowing the lead screw 6 to move axially relative to the main nut 5, enabling the lead screw 6 to drive the external actuator through the connector 9.

[0039] Alternatively, please refer to Figure 3 The worm gear 3 has a slot 31 at one end near the motor 2. The output shaft 21 of the motor 2 is inserted into the slot 31 and is fixedly connected to the worm gear 3. This configuration allows the output shaft 21 of the motor 2 to be directly inserted into a portion of the worm gear 3, reducing the axial dimension of the linear actuator along the worm gear 3. Furthermore, by controlling the machining accuracy, the concentricity of both can be ensured, eliminating the need for a coupling. Specifically, the worm gear 3 and the output shaft 21 of the motor 2 are connected by a single key with an interference fit. Preferably, the slot 31 comprises an inner groove and an outer groove that communicate with each other. The wall of the outer groove has an interference fit with the output shaft 21 of the motor 2, while the wall of the inner groove has a clearance fit with the output shaft 21 of the motor 2, facilitating assembly and disassembly and reducing the size of surfaces requiring high-precision machining.

[0040] Alternatively, please refer to Figure 2 In this embodiment, the linear actuator further includes a sleeve 10, which is rotatably connected to the mounting base 1 via multiple load-bearing bearings. The lead screw 6 passes through the sleeve 10, and the worm gear 4 and the main nut 5 are both fixedly installed on the sleeve 10, with the worm gear 4 and the main nut 5 arranged coaxially. In other embodiments, the worm gear 4 can also be directly coaxially fixed together with the main nut 5.

[0041] Alternatively, please refer to Figure 1 The linear actuator also includes a flat key 11, a keyway (not shown in the attached diagram) on the main nut 5, and a keyhole 101 on the sleeve 10. The flat key 11 is inserted into both the keyway and the keyhole 101. Adhesive is used to fill the inner walls of the flat key 11 and the keyway, and / or adhesive is used to fill the inner walls of the flat key 11 and the keyhole 101. This arrangement further connects the flat key 11 to the sleeve 10 and / or the flat key 11 to the main nut 5 using adhesive, preventing the flat key 11 from loosening and thus ensuring the safe operation of the linear actuator.

[0042] Alternatively, please refer to Figure 2The linear actuator also includes a bushing 12, which is located between the main nut 5 and the worm gear 4 along the axial direction of the sleeve 10. The bushing 12 is fixedly mounted on the sleeve 10, and the lead screw 6 passes through the bushing 12 and is slidably connected to the bushing 12. By setting the bushing 12, the lead screw 6 can be stably supported, ensuring that the lead screw 6 remains smooth during reciprocating motion and can always remain coaxial with the nut, avoiding noise. Preferably, the linear actuator includes multiple bushings 12, which are arranged sequentially along the axial direction of the sleeve 10. In this embodiment, an example of a linear actuator including two bushings 12 is given. More preferably, the bushing 12 is made of a self-lubricating material, which can be nylon, plastic steel, etc.

[0043] Alternatively, please continue to refer to Figure 2 The linear actuator also includes a safety nut 13, which is fixedly disposed on the sleeve 10 and sleeved on the lead screw 6. The safety nut 13 is configured to abut or separate from the lead screw 6 along the axial direction of the lead screw 6. Specifically, the thread profile of the safety nut 13 is slightly larger than that of the main nut 5. The pitch of the safety nut 13 is equal to that of the main nut 5. The thread profile of the main nut 5 matches the thread profile of the lead screw 6, and the pitch of the main nut 5 matches that of the lead screw 6. When the main nut 5 is in a normal, undamaged state, the main nut 5 and the lead screw 6 are normally screwed together, and there is a safety clearance between the safety nut 13 and the lead screw 6. At this time, the safety nut 13 does not function, and the main nut 5 can drive the lead screw 6 to reciprocate along its axial direction. When the main nut 5 is in a damaged state, it means that the thread of the main nut 5 is damaged, and the main nut 5 can no longer support the lead screw 6 normally, and therefore cannot drive the lead screw 6 to reciprocate along its axial direction. The lead screw 6 will generate axial displacement relative to the main nut 5 until it contacts the safety nut 13. At this time, the safety nut 13 supports the lead screw 6 to prevent it from falling off, thereby ensuring the safe use of the linear actuator.

[0044] Alternatively, please refer to Figure 4 Multiple load-bearing bearings include needle roller bearings 14 and two thrust bearings 15 respectively disposed on both sides of the needle roller bearings 14 along the axial direction of the sleeve 10. The needle roller bearings 14 and the two thrust bearings 15 are located between the worm gear 3 and the main nut 5. The thrust bearings 15 provide axial support, preventing the thrust from being transmitted to the worm wheel 4, while the needle roller bearings 14 provide radial support, ensuring that the rotational runout of the sleeve 10 is within a reasonable range. Specifically, when the lead screw 6 is under pressure, the force is transmitted from the lead screw 6 to the main nut 5, then from the main nut 5 to the sleeve 10, then from the sleeve 10 to the thrust bearings 15, and finally from the thrust bearings 15 to the mounting base 1. The force path ends at this point. Therefore, by setting two thrust bearings 15, the axial pressure of the lead screw 6 is prevented from being transmitted to the worm wheel 4, avoiding damage to the worm wheel 4 and the worm gear 3.

[0045] Alternatively, please refer to Figure 4 The multiple load-bearing bearings also include deep groove ball bearings 16. Along the axial direction of the sleeve 10, the deep groove ball bearings 16 and needle roller bearings 14 are located on both sides of the worm gear 4, and the outer ring of the deep groove ball bearing 16 is fixedly mounted on the mounting seat 1, while the inner ring of the deep groove ball bearing 16 is slidably fitted onto the sleeve 10. With this arrangement, the needle roller bearings 14 and the deep groove ball bearings 16 provide radial support from both sides of the worm gear 4. In particular, the deep groove ball bearings 16 can move relative to the sleeve 10 along the axial direction of the sleeve 10. Theoretically, the deep groove ball bearings 16 do not bear axial force, but only radial force, releasing the axial deformation of the sleeve 10 and ensuring that the axial force of the sleeve 10 is only transmitted to the thrust bearing 15, thereby ensuring stable transmission performance.

[0046] Alternatively, please continue to refer to Figure 1 The worm gear 3 has a first insertion part 32 at the end furthest from the motor 2. The first insertion part 32 is exposed on the mounting base 1 and is used to connect with the second insertion part of a wrench. This configuration allows the worm gear 3 to be driven to rotate via the second insertion part of the wrench and the first insertion part 32, ensuring safe operation even in the event of a power outage or malfunction. Specifically, one of the first insertion part 32 and the second insertion part of the wrench is a polygonal socket, and the other is a polygonal connector. The connector and socket are connected. The socket can be hexagonal or quadrilateral, etc. For example, in this embodiment, the first insertion part 32 has a hexagonal socket, and correspondingly, the second insertion part of the wrench has a hexagonal connector.

[0047] 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 linear actuator, comprising a mounting base (1), a motor (2) disposed on the mounting base (1), a worm gear (3) drivenly connected to the motor (2), a worm wheel (4) meshing with the worm gear (3), a main nut (5) drivenly connected to the worm wheel (4), and a lead screw (6) threadedly connected to the main nut (5), characterized in that, The linear actuator further includes: The first bearing (7) has its outer ring fixedly mounted on the mounting base (1) and its inner ring fixedly sleeved on the worm (3). The second bearing (8) is located away from the motor (2) relative to the first bearing (7). The outer ring of the second bearing (8) is fixedly installed on the mounting base (1). The inner ring of the second bearing (8) is sleeved on the worm (3), and the worm (3) can slide along the axial direction of the worm (3) relative to the inner ring of the second bearing (8).

2. The linear actuator according to claim 1, characterized in that, The linear actuator also includes a sleeve (10), which is rotatably connected to the mounting base (1) through multiple load-bearing bearings. The lead screw (6) passes through the sleeve (10), and the worm gear (4) and the main nut (5) are both fixedly installed on the sleeve (10), and the worm gear (4) and the main nut (5) are coaxially arranged.

3. The linear actuator according to claim 2, characterized in that, The linear actuator also includes a flat key (11), the main nut (5) is provided with a keyway, the sleeve (10) is provided with a keyhole (101), and the flat key (11) is inserted into the keyway and the keyhole (101) respectively; The inner wall of the flat key (11) and the keyway is filled with adhesive, and / or the inner wall of the flat key (11) and the keyhole (101) is filled with adhesive.

4. The linear actuator according to claim 2, characterized in that, The linear actuator also includes a bushing (12) along the axial direction of the sleeve (10). The bushing (12) is located between the main nut (5) and the worm gear (4). The bushing (12) is fixedly disposed on the sleeve (10). The lead screw (6) passes through the bushing (12) and is slidably connected to the bushing (12).

5. The linear actuator according to claim 4, characterized in that, The linear actuator includes a plurality of bushings (12), which are arranged sequentially along the axial direction of the sleeve (10); and / or, The bushing (12) is made of a self-lubricating material.

6. The linear actuator according to claim 2, characterized in that, The linear actuator further includes a safety nut (13), which is fixedly disposed on the sleeve (10) and sleeved on the lead screw (6). The safety nut (13) is configured to abut or separate from the lead screw (6) along the axial direction of the lead screw (6).

7. The linear actuator according to claim 2, characterized in that, The plurality of load-bearing bearings include needle roller bearings (14) and two thrust bearings (15) respectively disposed on both sides of the needle roller bearings (14) along the axial direction of the sleeve (10). The needle roller bearings (14) and the two thrust bearings (15) are located between the worm (3) and the main nut (5).

8. The linear actuator according to claim 7, characterized in that, The plurality of load-bearing bearings also include deep groove ball bearings (16). Along the axial direction of the sleeve (10), the deep groove ball bearings (16) and the needle roller bearings (14) are located on both sides of the worm gear (4), and the outer ring of the deep groove ball bearings (16) is fixedly disposed on the mounting base (1), and the inner ring of the deep groove ball bearings (16) is slidably sleeved on the sleeve (10).

9. The linear actuator according to claim 1, characterized in that, The worm (3) has a slot (31) at one end near the motor (2), the output shaft (21) of the motor (2) is inserted into the slot (31), and the output shaft (21) of the motor (2) is fixedly connected to the worm (3).

10. The linear actuator according to any one of claims 1-9, characterized in that, The worm (3) has a first plug-in part (32) at the end away from the motor (2). The first plug-in part (32) is exposed on the mounting base (1) and is used to plug into the second plug-in part of the wrench.

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