Lead screw assembly and actuator

Abstract

The utility model provides a lead screw assembly and an actuator. The lead screw assembly comprises a nut, a lead screw and a plurality of balls, the nut is arranged on the lead screw in a sleeving mode, a channel in the nut is matched with a channel in the lead screw to form a rolling channel, the balls are arranged in the rolling channel, and the lead screw assembly further comprises at least one retainer and a stop device. The retainer is movably arranged between the nut and the screw rod along the rolling channel, and the retainer is used for fixing the relative position between the adjacent balls; the retaining devices are arranged in the grooves in the nut or the grooves in the lead screw, and one retainer corresponds to one pair of retaining devices and is used for limiting the movement range of the retainer. According to the lead screw assembly, circulation is not needed, the machining difficulty of the lead screw assembly is reduced, and the lead screw assembly can be applied to the scene with the small lead screw size.

Description

Technical Field

[0001] This disclosure relates to the field of actuator technology, and in particular to a lead screw assembly and an actuator. Background Technology

[0002] Ball screws are a key component of electric cylinders. They convert rotational motion into linear motion by having balls roll in the helical channels of the screw and nut. Typically, ball screws have ball circulation channels on the nut or screw to form a closed path, allowing the balls to return to their starting point for a cycle. However, when ball screws are very small, machining these circulation channels on the screw or nut to achieve ball circulation is extremely difficult, and sometimes impossible. Utility Model Content

[0003] This disclosure provides a lead screw assembly and an electric cylinder.

[0004] In a first aspect, embodiments of this disclosure provide a lead screw assembly, including a nut, a lead screw, and a plurality of balls. The nut is sleeved on the lead screw, and the grooves on the nut and the lead screw match to form a rolling channel. The plurality of balls are disposed in the rolling channel. The lead screw assembly further includes at least one retainer and a stop device. The retainer is movably disposed between the nut and the lead screw along the rolling channel, and the retainer is used to space adjacent balls apart. The stop device is disposed in the grooves on the nut or the lead screw, with one retainer corresponding to one pair of stop devices, for limiting the range of motion of the retainer.

[0005] In some embodiments, the stop device includes a main body and a mounting part; the main body is disposed in a groove on the nut or a groove on the lead screw, and the main bodies of a pair of stop devices are respectively located at both ends of the groove on the nut or the groove on the lead screw, and the mounting part is used to be fixedly connected to the nut or the lead screw.

[0006] In some embodiments, the mounting part is fixedly connected to the nut or the lead screw by means of bolts, adhesive, clips, pins, etc.

[0007] In some embodiments, the stop device is disposed in the groove on the nut, and the surface shape of the main body on the side opposite to the mounting portion matches the groove shape on the lead screw; the mounting portion is provided with bolt holes, and is fixed to the end face of the nut by bolts.

[0008] In some embodiments, a first mounting groove is provided on the end face of the nut, the shape of the first mounting groove matching the shape of the mounting part; the mounting part is installed in the first mounting groove.

[0009] In some embodiments, the stop device is disposed in a groove on the lead screw, and the surface shape of the main body on the side opposite to the mounting portion matches the groove shape on the nut; the mounting portion is provided with bolt holes and is fixed to the end face of the lead screw by bolts.

[0010] In some embodiments, a second mounting groove is provided on the end face of the lead screw, the shape of the second mounting groove matching the shape of the mounting part; the mounting part is installed in the second mounting groove.

[0011] In some embodiments, the retainer is a spiral structure, the extension direction of the spiral structure matching the extension direction of the rolling channel; the retainer is provided with a plurality of positioning holes, and the ball is disposed in the positioning holes and can rotate in the positioning holes.

[0012] In some embodiments, two protrusions are provided opposite to each other on the edge of the positioning hole, and the concave surface of the protrusions facing the positioning hole matches the shape of the ball, so that the ball can rotate in the positioning hole without falling out.

[0013] In some embodiments, the length of the retainer and the length of the groove between the pair of stops are matched with the stroke of the lead screw assembly.

[0014] In some embodiments, the number of groove turns corresponding to the difference between the length of the groove between a pair of stop devices and the length of the retainer is greater than or equal to the number of groove turns corresponding to the stroke of the lead screw assembly.

[0015] In some embodiments, the stroke of the lead screw assembly is less than or equal to 5 times the lead of the lead screw assembly.

[0016] In a second aspect, embodiments of this disclosure also provide an actuator, the actuator including a lead screw assembly and a drive assembly as described in the first aspect of embodiments of this disclosure, the drive assembly driving the lead screw assembly to move.

[0017] In this embodiment, the ball screw assembly includes a nut, a lead screw, and a plurality of balls. The balls are disposed in a rolling channel formed by matching grooves on the nut and the lead screw via retainers, thereby fixing the relative positions of adjacent balls. By means of two stop devices disposed at both ends of the grooves, the range of motion of the retainers can be limited, preventing the balls from coming out of the grooves of the nut or the lead screw. This achieves a ball screw assembly that does not require ball circulation, thus eliminating the need to machine circulation grooves in the lead screw or nut, reducing the machining difficulty of the ball screw, and making it suitable for applications with smaller lead screw sizes. Attached Figure Description

[0018] Figure 1This is a three-dimensional structural diagram of a reverse ball screw according to an embodiment of the present disclosure;

[0019] Figure 2 yes Figure 1 A schematic diagram of the screw of a reversible ball screw;

[0020] Figure 3 This is a schematic diagram of the spiral structure of a retainer for a lead screw assembly according to an embodiment of the present disclosure;

[0021] Figure 4 yes Figure 3 A schematic diagram showing the unfolded spiral structure of the middle retainer;

[0022] Figure 5 yes Figure 4 A cross-sectional schematic diagram of the spiral structure of the retainer in its unfolded state;

[0023] Figure 6 This is a three-dimensional structural schematic diagram of a positive ball screw according to an embodiment of the present disclosure;

[0024] Figure 7 yes Figure 6 A schematic diagram of the nut structure of a positive-direction ball screw.

[0025] Explanation of reference numerals in the attached figures:

[0026] 1. Nut; 2. Lead screw; 3. Ball bearing; 4. Retainer; 41. Positioning hole; 42. Limiting structure; 43. Limiting part; 44. Protrusion; 5. Stopping device; 51. Main body; 52. Mounting part; 53. Bolt hole; 6. Groove; 61. First groove; 62. Second groove; 63. Rolling channel. Detailed Implementation

[0027] To enable those skilled in the art to better understand the technical solutions of this disclosure, the technical solutions of this disclosure will be described in detail below with reference to the accompanying drawings.

[0028] Exemplary embodiments will be described more fully below with reference to the accompanying drawings; however, these exemplary embodiments may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will enable those skilled in the art to fully understand the scope of this disclosure.

[0029] Where there is no conflict, the various embodiments of this disclosure and the features thereof in the embodiments may be combined with each other.

[0030] As used herein, the term “and / or” includes any and all combinations of one or more related enumerated entries.

[0031] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. As used herein, the singular forms “a” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It will also be understood that when the terms “comprising” and / or “made of” are used in this specification, the presence of the stated feature, integral, step, operation, element, and / or component is specified, but the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof is not excluded.

[0032] The embodiments described herein can be described with reference to plan views and / or cross-sectional views using the ideal schematic diagrams of this disclosure. Therefore, the example illustrations can be modified according to manufacturing techniques and / or tolerances. Therefore, the embodiments are not limited to those shown in the drawings, but include modifications to configurations formed based on manufacturing processes. Therefore, the areas illustrated in the drawings are schematic in nature, and the shapes of the areas shown in the figures illustrate specific shapes of areas of an element, but are not intended to be limiting.

[0033] Unless otherwise specified, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art. It will also be understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and this disclosure, and will not be interpreted as having an idealized or overly formal meaning, unless expressly so defined herein.

[0034] In this embodiment of the present disclosure, a ball screw in which the balls are arranged in the groove of the nut and the nut is driven to move linearly by the rotation of the screw is a forward ball screw; a ball screw in which the balls are arranged in the groove of the screw and the screw is driven to move linearly by the rotation of the nut is a reverse ball screw.

[0035] The lead screw assembly provided in this disclosure can be either a forward ball screw or a reverse ball screw. This disclosure does not impose any special limitations on this type of assembly.

[0036] Figure 1 This is a perspective view of a lead screw assembly according to an embodiment of the present disclosure. Figure 1 The lead screw assembly in the system is a reverse ball screw. Figure 2 yes Figure 1 A 3D view of the lead screw of the lead screw assembly.

[0037] like Figure 1As shown, the lead screw assembly includes a nut 1, a lead screw 2, balls 3, a retainer 4, and a stop device 5. Both the nut 1 and the lead screw 2 have grooves 6. The first groove 61 on the nut and the second groove 62 on the lead screw 2 match to form a rolling channel 63, in which multiple balls 3 are disposed. The nut 1 and the lead screw 2 mesh with each other through the balls 3. The rotation of the nut 1 drives the lead screw 2 to move linearly, thus converting rotational motion into linear motion. The retainer 4 is disposed between the nut 1 and the lead screw 2 along the rolling channel 63. The balls 3 are disposed on the retainer 4, which has a clearance fit with the first groove 61 on the nut 1 and the second groove 62 on the lead screw 2. The retainer 4 can move between the nut 1 and the lead screw 2 along the extension direction of the second groove 62. The stop device 5 is disposed in the second groove 62. One retainer 4 corresponds to one pair of stop devices 5, and the retainer 4 is disposed between two stop devices 5. The stop device 5 is used to limit the range of motion of the retainer 4 on the lead screw 2. For example, when the nut 1 rotates and drives the lead screw 2 to move linearly, the ball 3 rolls in the second groove 62, causing the retainer 4 to move along the extension direction of the second groove 62. When the retainer 4 contacts the stop device 5 on either side, it stops moving. The stop device 5 thus limits the range of motion of the retainer 4, that is, the retainer 4 can only move between its corresponding pair of stop devices 5.

[0038] The embodiments disclosed herein aim to achieve ball screws that do not require recirculation. For example... Figure 1 , Figure 2 As shown, the lead screw 2 does not have a circulation raceway for the balls 3 to circulate, and the balls 3 do not fill the second groove 62. With the stop device 5 installed, if the balls 3 were to fill the second groove 62, they would be unable to circulate and roll. However, by leaving the second groove 62 partially filled, space is reserved for the balls 3 to roll within it. Even without a circulation raceway in the lead screw 2, the balls 3 can still roll within the second groove 62. Thus, through the meshing action of the first groove 61, the balls 3, and the second groove 62, the rotational motion of the nut 1 can be converted into the linear motion of the lead screw 2. When the balls 3 do not fill the second groove 62, the length of the groove outside the two balls 3 at both ends of the second groove 62 is considered as the rolling space for all the balls 3 as a whole. Based on this, a retainer 4 is set to keep the relative positions of adjacent balls 3 fixed, which also fixes the overall rolling space of all balls 3, preventing the misalignment of the balls 3 in the second groove 62 from affecting the smooth operation of the ball screw.

[0039] The present invention does not impose any special limitation on the number of retainers 4 provided in the lead screw assembly.

[0040] In some embodiments, a plurality of retainers 4 are provided in the lead screw assembly, each retainer 4 corresponding to a pair of stop devices 5, the pair of stop devices 5 corresponding to a segment of a second channel 62, the stop devices 5 being disposed in the second channel 62.

[0041] In this embodiment, the load of the lead screw assembly is positively correlated with the number of turns of the balls 3 in the second groove 62; the more turns of the balls 3, the greater the load on the lead screw assembly. However, more turns of consecutive balls 3 in the second groove 62 is not necessarily better; after a certain number of turns, the load efficiency decreases. Therefore, by providing multiple retainers 4 and correspondingly multiple pairs of stop devices 5 in the lead screw assembly, the balls 3 in the second groove 62 are divided into multiple groups, which helps to improve load efficiency.

[0042] In some embodiments, such as Figure 1 , Figure 2 As shown, the lead screw assembly is provided with a retainer 4 and two stop devices 5 are respectively provided at both ends of the second channel 62.

[0043] In this embodiment of the disclosure, the length of the retainer 4 and the length of the channel between the pair of stop devices 5 are matched with the stroke of the lead screw assembly.

[0044] In some embodiments, the length of the retainer 4, the length of the groove between the pair of stop devices 5, and the stroke of the lead screw assembly are matched. This means that when the nut 1 rotates to drive the lead screw 2 to move linearly from the starting point to the other end, the difference between the length of the second groove 62 between the pair of stop devices 5 and the length of the retainer 4 is not less than the distance the ball 3 rolls in the second groove 62. For example, the number of groove turns corresponding to the difference between the length of the groove between the pair of stop devices 5 and the length of the retainer 4 is greater than or equal to the number of groove turns corresponding to the stroke of the lead screw assembly.

[0045] like Figure 1 , Figure 2 As shown, the stop device 5 includes a main body 51 and a mounting part 52. The main body is disposed in the second groove 62 on the lead screw 2. The main bodies 51 of a pair of stop devices 5 are respectively located at both ends of the second groove 62 on the lead screw 2. The mounting part 52 is used to fix the main body 51 in the second groove 62, thereby preventing the retainer 4 from moving further.

[0046] This embodiment does not impose any special limitations on how the mounting part 52 is fixedly connected to the lead screw 2. For example, the mounting part 52 can be fixedly connected to the lead screw 2 by means of bolts, adhesive, clips, pins, etc.

[0047] like Figure 1 , Figure 2As shown, the surface shape of the main body 51 on the side opposite to the mounting part 52 matches the shape of the first groove 61 on the nut 1. The mounting part 52 is provided with bolt holes 53, which are fixed to the end face of the lead screw 2 by bolts.

[0048] like Figure 1 , Figure 2 As shown, a mounting groove is also provided on the end face of the lead screw 2. The shape of the mounting groove matches the shape of the mounting part 52. The mounting part is installed in the mounting groove and further fixed by bolts.

[0049] Figure 3 This is a schematic diagram of a retainer according to an embodiment of the present disclosure.

[0050] like Figure 3 As shown, the retainer 4 is an integrally formed spiral structure, and the extension direction of the spiral structure matches the extension direction of the second groove 62 on the lead screw 2. The retainer 4 is provided with multiple positioning holes 41, and the balls 3 are disposed in the positioning holes 41, thereby keeping the relative positions of adjacent balls 3 fixed. The balls 3 can rotate in the positioning holes 41, and thus can roll in the second groove 62 to drive the retainer 4 to move spirally along the extension direction of the second groove 62.

[0051] This disclosure does not specifically limit the length of the retainer 4. In some embodiments, the length of the retainer 4 is no greater than the length of 6 turns of the second channel 62. For example, the length of the retainer 4 matches the length of 3 or 4 turns of the second channel 62. Figure 1 , Figure 2 As shown, the length of the retainer 4 matches the length of the three turns of the second groove 62, and the retainer 4 contains three turns of balls 3. The length of the retainer 4 not exceeding the length of the six turns of the second groove 62 can balance the maximum load and load efficiency of the ball screw.

[0052] like Figure 3 , Figure 4 , Figure 5 As shown, two protrusions 44 are provided opposite to each other on the edge of the positioning hole 41. The concave surface of the protrusions 44 facing the positioning hole 41 matches the shape of the ball. The ball 3 can rotate in the positioning hole 41 without falling out, which is convenient for installation.

[0053] Figure 4 This is a schematic diagram of the spiral structure of the retainer 4 in this embodiment of the present disclosure. The spiral structure has a plurality of continuous positioning holes 41 with a certain interval between adjacent positioning holes 41. Each positioning hole 41 has an internal space. The width and depth of the positioning hole 41 are suitable for accommodating and retaining the ball 3. The inner diameter of the positioning hole 41 is able to allow the ball 3 to roll freely therein.

[0054] Figure 5This is a cross-sectional schematic diagram of the unfolded state of the spiral structure of the retainer 4 in an embodiment of this disclosure, referring to... Figure 5 A limiting structure 42 matching the shape of the ball 3 is provided at the edge of the positioning hole 41. The limiting structure 42 contacts the outer peripheral surface of the ball 3 to limit the position of the ball 3 and prevent the ball 3 from coming out of the positioning hole 41. The limiting structure 42 includes a limiting part 43 and a protrusion 44. The protrusion 44 is fixedly connected to the limiting part 43, together forming the positioning hole 41. The protrusion 44 is arranged along the axis of the spiral extension direction of the retainer 4. The height of the protrusion 44 is higher than the height of the limiting part 43, and the height of the protrusion 44 is lower than the diameter of the ball 3. The limiting structure 43 can ensure that the ball maintains a stable position in the positioning hole, prevent the ball from coming out or shifting, provide mechanical restraint, and meet the positioning requirements.

[0055] In some embodiments, the protrusion 44 of the limiting structure 42 may be a raised annular edge, an annular shoulder, a stepped structure, or other forms of mechanical limiting device, which are not specifically limited in this disclosure. For example, the protrusion 44 may be an annular edge.

[0056] In some embodiments, the retainer is made of a rigid or elastic material. For example, the retainer is made of materials such as plastic, resin, or metal. This disclosure does not specifically limit the embodiments in this regard.

[0057] In some embodiments, the retainer material has suitable elasticity and strength, allowing the balls greater flexibility and adaptability within the retainer. For example, the retainer is flat injection molded, a flexible injection-molded elastomer made of plastic.

[0058] This disclosure does not impose any special limitations on the manufacturing process of the retainer. For example, the retainer can be manufactured by molding processes including but not limited to injection molding, casting, powder metallurgy, 3D printing, etc.

[0059] In some embodiments, the lead screw assembly provided in this disclosure is a short-stroke lead screw assembly. In some embodiments, the stroke of the lead screw assembly provided in this disclosure is less than or equal to 5 times the lead of the lead screw assembly. For example, the stroke of the lead screw assembly is 5 times, 4.5 times, 4 times, 3.5 times, 3 times, 2.5 times, 2 times, 1.5 times, 1 time, etc., of the lead.

[0060] It should be noted that in a reverse ball screw, the lead refers to the linear distance the screw moves axially when the nut rotates one revolution; the stroke refers to the maximum distance the screw can move axially.

[0061] In the embodiments of this disclosure, in the scenario of short-stroke lead screw assembly, by setting a retainer, it is not necessary to open a circulating raceway in the lead screw, thus overcoming the problem that it is impossible to realize a ball screw because it is impossible to open a circulating raceway in a small-sized lead screw, and reducing the design and manufacturing difficulty of the ball screw.

[0062] Figure 6 This is a perspective view of another lead screw assembly in an embodiment of this disclosure. Figure 6 The lead screw assembly in the system is a forward ball screw. Figure 7 yes Figure 6 A 3D view of the nut in the lead screw assembly.

[0063] like Figure 6 As shown, the lead screw assembly includes a nut 1, a lead screw 2, balls 3, a retainer 4, and a stop device 5. Both the nut 1 and the lead screw 2 have grooves 6. The first groove 61 on the nut and the second groove 62 on the lead screw 2 match to form a rolling channel 63, in which multiple balls 3 are disposed. The nut 1 and the lead screw 2 mesh with each other through the balls 3. The rotation of the lead screw 2 drives the nut 1 to move linearly, thus converting rotational motion into linear motion. The retainer 4 is disposed between the nut 1 and the lead screw 2 along the rolling channel 63. The balls 3 are disposed on the retainer 4, which has a clearance fit with the first groove 61 on the nut 1 and the second groove on the lead screw 2. The retainer 4 can move between the nut 1 and the lead screw 2 along the extension direction of the first groove 61. The stop device 5 is disposed in the first groove 61. One retainer 4 corresponds to one pair of stop devices 5, and the retainer 4 is disposed between two stop devices 5. The stop device 5 is used to limit the range of motion of the retainer 4 on the nut 1. For example, when the lead screw 2 rotates and drives the nut 1 to move linearly, the ball 3 rolls in the first groove 61, causing the retainer 4 to move along the extension direction of the first groove 61. When the retainer 4 contacts the stop device 5 on either side, it stops moving. The stop device 5 thus limits the range of motion of the retainer 4, that is, the retainer 4 can only move between its corresponding pair of stop devices 5.

[0064] The embodiments disclosed herein aim to achieve ball screws that do not require recirculation. For example... Figure 6 , Figure 7 As shown, the nut 1 does not have a circulation raceway for the balls 3, and the balls 3 do not fill the first groove 61. When the balls 3 do not fill the first groove 61, the length of the groove outside the two balls 3 at both ends of the first groove 61 serves as the rolling space for all the balls 3 as a whole. Based on this, a retainer 4 is provided to keep the relative positions of adjacent balls 3 fixed, thus fixing the rolling space for all the balls 3 as a whole and preventing misalignment of the balls 3 in the first groove 61 from affecting the smooth operation of the ball screw.

[0065] The present invention does not impose any special limitation on the number of retainers 4 provided in the lead screw assembly.

[0066] In some embodiments, a plurality of retainers 4 are provided in the lead screw assembly, each retainer 4 corresponding to a pair of stop devices 5, the pair of stop devices 5 corresponding to a segment of a first channel 61, the stop devices 5 being disposed in the first channel 61.

[0067] In this embodiment, the load of the lead screw assembly is positively correlated with the number of turns of the balls 3 disposed in the first groove 61; the more turns of the balls 3, the greater the load of the lead screw assembly. However, the number of consecutive turns of the balls 3 disposed in the first groove 61 is not necessarily better the more numerous they are; after the number of consecutive turns of the balls 3 exceeds a certain amount, the load efficiency will decrease. Therefore, multiple retainers 4 are provided in the lead screw assembly, and multiple pairs of stop devices 5 are correspondingly provided, dividing the balls 3 in the first groove 61 into multiple groups, which is beneficial to improving the load efficiency.

[0068] In some embodiments, such as Figure 6 , Figure 7 As shown, the lead screw assembly is provided with a retainer 4 and two stop devices 5 are respectively provided at both ends of the first channel 61.

[0069] In this embodiment of the disclosure, the length of the retainer 4 and the length of the channel between the pair of stop devices 5 are matched with the stroke of the lead screw assembly.

[0070] In some embodiments, the length of the retainer 4, the length of the groove between the pair of stop devices 5, and the stroke of the lead screw assembly are matched. This means that when the lead screw 2 rotates to drive the nut 1 to move linearly from the starting point to the other end, the difference between the length of the first groove 61 between the pair of stop devices 5 and the length of the retainer 4 is not less than the distance the ball 3 rolls in the first groove 61. For example, the number of groove turns corresponding to the difference between the length of the groove between the pair of stop devices 5 and the length of the retainer 4 is greater than or equal to the number of groove turns corresponding to the stroke of the lead screw assembly.

[0071] like Figure 6 , Figure 7 As shown, the stop device 5 includes a main body 51 and a mounting part 52. The main body is disposed in the first groove 61 on the nut 1. The main bodies 51 of a pair of stop devices 5 are respectively located at both ends of the first groove 61 on the nut 1. The mounting part 52 is used to fix the main body 51 in the first groove 61, thereby preventing the retainer 4 from moving further.

[0072] This embodiment does not impose any special limitations on how the mounting part 52 is fixedly connected to the nut 1. For example, the mounting part 52 can be fixedly connected to the nut 1 by means of bolts, adhesive, clips, pins, etc.

[0073] like Figure 6 , Figure 7 As shown, the surface shape of the main body 51 on the side opposite to the mounting part 52 matches the shape of the second groove 62 on the lead screw 2. The mounting part 52 is provided with bolt holes 53, which are fixed to the end face of the nut 1 by bolts.

[0074] like Figure 6 , Figure 7 As shown, a mounting groove is also provided on the end face of the nut 1. The shape of the mounting groove matches the shape of the mounting part 52. The mounting part 52 is installed in the mounting groove and further fixed by bolts.

[0075] Figure 3 This is a schematic diagram of a retainer according to an embodiment of the present disclosure.

[0076] like Figure 3 As shown, the retainer 4 is an integrally formed spiral structure, and the extension direction of the spiral structure matches the extension direction of the first groove 61 on the nut 1. The retainer 4 is provided with multiple positioning holes 41, and the balls 3 are disposed in the positioning holes 41, thereby keeping the relative positions of adjacent balls 3 fixed. The balls 3 can rotate in the positioning holes 41, and thus can roll in the first groove 61 to drive the retainer 4 to move spirally along the extension direction of the first groove 61.

[0077] This disclosure does not specifically limit the length of the retainer 4. In some embodiments, the length of the retainer 4 is no greater than the length of 6 turns of the first channel 61. For example, the length of the retainer 4 matches the length of 3 or 4 turns of the first channel 61. Figure 6 , Figure 7 As shown, the length of the retainer 4 matches the length of the three turns of the first groove 61, and the retainer 4 contains three turns of balls 3. The length of the retainer 4 not exceeding the length of the six turns of the first groove 61 can balance the maximum load and load efficiency of the ball screw.

[0078] like Figure 3 , Figure 4 , Figure 5 As shown, two protrusions 44 are provided opposite to each other on the edge of the positioning hole 41. The concave surface of the protrusions 44 facing the positioning hole 41 matches the shape of the ball. The ball 3 can rotate in the positioning hole 41 without falling out, which is convenient for installation.

[0079] Figure 4 This is a schematic diagram of the spiral structure of the retainer 4 in this embodiment of the present disclosure. The spiral structure has a plurality of continuous positioning holes 41 with a certain interval between adjacent positioning holes 41. Each positioning hole 41 has an internal space. The width and depth of the positioning hole 41 are suitable for accommodating and retaining the ball 3. The inner diameter of the positioning hole 41 is able to allow the ball 3 to roll freely therein.

[0080] Figure 5 This is a cross-sectional schematic diagram of the unfolded state of the spiral structure of the retainer 4 in an embodiment of this disclosure, referring to... Figure 5 A limiting structure 42 matching the shape of the ball 3 is provided at the edge of the positioning hole 41. The limiting structure 42 contacts the outer peripheral surface of the ball 3 to limit the position of the ball 3 and prevent the ball 3 from coming out of the positioning hole 41. The limiting structure 42 includes a limiting part 43 and a protrusion 44. The protrusion 44 is fixedly connected to the limiting part 43, together forming the positioning hole 41. The protrusion 44 is arranged along the axis of the spiral extension direction of the retainer 4. The height of the protrusion 44 is higher than the height of the limiting part 43, and the height of the protrusion 44 is lower than the diameter of the ball 3. The limiting structure 43 can ensure that the ball maintains a stable position in the positioning hole, prevent the ball from coming out or shifting, provide mechanical restraint, and meet the positioning requirements.

[0081] In some embodiments, the protrusion 44 of the limiting structure 42 may be a raised annular edge, an annular shoulder, a stepped structure, or other forms of mechanical limiting device, which are not specifically limited in this disclosure. For example, the protrusion 44 may be an annular edge.

[0082] In some embodiments, the retainer is made of a rigid or elastic material. This disclosure does not specifically limit this. For example, the retainer may be made of materials such as plastic, resin, or metal. This disclosure does not specifically limit this.

[0083] In some embodiments, the retainer material has suitable elasticity and strength, allowing the balls greater flexibility and adaptability within the retainer. For example, the retainer is flat injection molded, a flexible injection-molded elastomer made of plastic.

[0084] This disclosure does not impose any special limitations on the manufacturing process of the retainer. For example, the retainer can be manufactured by molding processes including but not limited to injection molding, casting, powder metallurgy, 3D printing, etc.

[0085] In some embodiments, the lead screw assembly provided in this disclosure is a short-stroke lead screw assembly. In some embodiments, the stroke of the lead screw assembly provided in this disclosure is less than or equal to 5 times the lead of the lead screw assembly. For example, the stroke of the lead screw assembly is 5 times, 4.5 times, 4 times, 3.5 times, 3 times, 2.5 times, 2 times, 1.5 times, 1 time, etc., of the lead.

[0086] It should be noted that in a forward ball screw, the lead refers to the linear distance the nut moves axially during one revolution of the screw; the stroke refers to the maximum distance the nut can move axially.

[0087] In the embodiments of this disclosure, in the scenario of short forming screw assembly, by setting a retainer, it is not necessary to open a circulating raceway in the screw, which overcomes the problem that it is impossible to open a circulating raceway in a small-sized screw and thus cannot realize a ball screw, reducing the design and processing difficulty of the ball screw.

[0088] This disclosure also provides an actuator that includes any of the above-described lead screw assembly and a drive assembly, wherein the drive assembly is used to drive the lead screw assembly to move.

[0089] In some embodiments, the drive component is an electric drive component, and the actuator is an electric cylinder.

[0090] Example embodiments have been disclosed herein, and while specific terminology has been used, it is for illustrative purposes only and should be construed as such, and is not intended to be limiting. In some instances, it will be apparent to those skilled in the art that features, characteristics, and / or elements described in connection with particular embodiments may be used alone, or in combination with features, characteristics, and / or elements described in connection with other embodiments, unless otherwise expressly indicated. Therefore, those skilled in the art will understand that various changes in form and detail may be made without departing from the scope of this disclosure as set forth by the appended claims.

Claims

1. A lead screw assembly, comprising a nut (1), a lead screw (2), and a plurality of balls (3), wherein the nut (1) is sleeved on the lead screw (2), and the grooves on the nut (1) match the grooves on the lead screw (2) to form a rolling channel (63), and the plurality of balls (3) are disposed in the rolling channel (63), characterized in that, The lead screw assembly also includes at least one retainer (4) and a stop device (5); The retainer (4) is movably disposed between the nut (1) and the lead screw (2) along the rolling channel (63), and the retainer (4) is used to fix the relative position between adjacent balls (3); The stop device (5) is disposed in the groove on the nut (1) or the groove on the lead screw (2), and one retainer (4) corresponds to a pair of stop devices (5) for limiting the range of motion of the retainer (4).

2. The lead screw assembly according to claim 1, characterized in that, The stop device (5) includes a main body (51) and a mounting part (52); The main body (51) is disposed in the groove on the nut (1) or the groove on the lead screw (2). The main body (51) of a pair of stop devices (5) are respectively located at both ends of the groove on the nut (1) or the groove on the lead screw (2). The mounting part (52) is used to fix it to the nut (1) or the lead screw (2).

3. The lead screw assembly according to claim 2, characterized in that, The mounting part (52) is fixedly connected to the nut (1) or the lead screw (2) by means of bolts, glue, clips, pins, etc.

4. The lead screw assembly according to claim 3, characterized in that, The stop device (5) is disposed in the groove on the nut (1), and the surface shape of the main body (51) on the side opposite to the mounting part (52) matches the groove shape on the lead screw (2); The mounting part (52) is provided with bolt holes (53), which are fixed to the end face of the nut (1) by bolts.

5. The lead screw assembly according to claim 4, characterized in that, The nut (1) has a first mounting groove on its end face, and the shape of the first mounting groove matches the shape of the mounting part (52); the mounting part (52) is installed in the first mounting groove.

6. The lead screw assembly according to claim 3, characterized in that, The stop device (5) is disposed in the groove on the lead screw (2), and the surface shape of the main body (51) on the side opposite to the mounting part (52) matches the groove shape on the nut (1); The mounting part (52) is provided with bolt holes (53), which are fixed to the end face of the lead screw (2) by bolts.

7. The lead screw assembly according to claim 6, characterized in that, A second mounting groove is provided on the end face of the lead screw (2), and the shape of the second mounting groove matches the shape of the mounting part (52); the mounting part (52) is installed in the second mounting groove.

8. The lead screw assembly according to any one of claims 1 to 7, characterized in that, The retainer (4) has a spiral structure, and the extension direction of the spiral structure matches the extension direction of the rolling channel (63). The retainer (4) is provided with a plurality of positioning holes (41), and the ball (3) is disposed in the positioning holes (41) and can rotate in the positioning holes (41).

9. The lead screw assembly according to claim 8, characterized in that, The positioning hole (41) has two protrusions (44) on opposite sides. The concave surface of the protrusions (44) facing the positioning hole (41) matches the shape of the ball. The ball (3) can rotate in the positioning hole (41) without coming out.

10. The lead screw assembly according to any one of claims 1 to 7, characterized in that, The length of the retainer (4) and the length of the groove between the pair of stop devices (5) are matched with the stroke of the lead screw assembly.

11. The lead screw assembly according to claim 10, characterized in that, The number of groove turns corresponding to the difference between the length of the groove between the pair of stop devices (5) and the length of the retainer (4) is greater than or equal to the number of groove turns corresponding to the stroke of the lead screw assembly.

12. The lead screw assembly according to any one of claims 1 to 7, characterized in that, The stroke of the lead screw assembly is less than or equal to 5 times the lead of the lead screw assembly.

13. The lead screw assembly according to any one of claims 1 to 7, characterized in that, The retainer (4) is made of rigid or elastic material.

14. An actuator, characterized in that, The actuator includes a lead screw assembly and a drive assembly as described in any one of claims 1 to 13, wherein the drive assembly drives the lead screw assembly to move.

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