Linear servo electric cylinder

Abstract

According to the linear servo electric cylinder, a pull rope sensor is fixedly installed at the rear end of a shell, and a pull rope output from the pull rope sensor penetrates through a roller lead screw transmission structure, then enters a movable sleeve, penetrates through a fixed pulley in the movable sleeve and then is fixedly connected with the other end, penetrating through an end cover, of the roller lead screw transmission structure; the pull rope sensor is integrally arranged in the shell of the linear servo electric cylinder, a sensor cable does not need to be reserved outside the servo electric cylinder, the situation that the sensor cable moves along with the output end of the electric cylinder during measurement is avoided, and the situation that the exposed sensor cable is prone to damage is avoided.

Description

Technical Field

[0001] The present application relates to the technical field of servo electric cylinders, and in particular to a linear servo electric cylinder. Background Art

[0002] Currently, servo cylinders use a servo motor, coupled to a synchronous belt or directly to a coupling, to drive a ball screw, achieving precise control of linear motion. To detect the force applied to the cylinder's output, a pressure sensor is typically added. Because the pressure sensor cable must be connected to and follow the cylinder's output, a certain length of sensor cable must be left outside the servo cylinder. Exposed sensor cable is susceptible to damage. Summary of the Invention

[0003] In order to solve the above problems, the purpose of the embodiments of the present application is to provide a linear servo electric cylinder.

[0004] In a first aspect, an embodiment of the present application provides a linear servo electric cylinder, comprising: a housing, a bearing, a roller screw transmission structure as a rotor, a coil stator, a movable sleeve, a spring, and a fixed pulley;

[0005] The coil stator is fixed on the inner side of the shell, and the front end of the shell is provided with an end cover;

[0006] The roller screw transmission structure is located on the inner side of the coil stator and is rotatably connected to the housing through a bearing. One end of the roller screw transmission structure is located inside the housing, and the other end of the roller screw transmission structure passes through the end cover and is located outside the housing. The movable sleeve is slidably connected to the other end of the roller screw transmission structure that passes through the end cover.

[0007] The spring is respectively connected to the inner bottom end of the movable sleeve and the other end of the roller screw transmission structure passing through the end cover;

[0008] The fixed pulley is fixed to the inner bottom end of the movable sleeve, and the fixed pulley is located inside the spring;

[0009] The draw rope sensor is fixedly mounted on the inner end face of the rear end of the housing. The draw rope output from the draw rope sensor passes through the roller screw transmission structure and enters the movable sleeve. After passing through the fixed pulley in the movable sleeve, the draw rope is fixedly connected to the other end of the roller screw transmission structure passing through the end cover.

[0010] In the solution provided in the first aspect of the embodiment of the present application, the pull rope sensor is fixedly installed at the rear end of the shell, and the pull rope output from the pull rope sensor passes through the roller screw transmission structure and enters the movable sleeve, and passes through the fixed pulley in the movable sleeve and is fixedly connected to the other end of the roller screw transmission structure through the end cover. Compared with the related art that requires a certain length of sensor cable to be reserved outside the servo electric cylinder, and the sensor cable needs to move with the output end of the electric cylinder when detecting the force at the output end of the electric cylinder, the pull rope sensor is arranged as a whole in the shell of the linear servo electric cylinder. During measurement, the sensor cable does not need to move with the output end of the electric cylinder, and there is no need to reserve a sensor cable outside the servo electric cylinder, which avoids the situation where the exposed sensor cable is easily damaged.

[0011] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0013] Figure 1 A schematic structural diagram of a linear servo electric cylinder provided in an embodiment of the present application is shown;

[0014] Figure 2 The embodiment of the present application provides Figure 1 A local enlarged schematic diagram;

[0015] Figure 3 The schematic diagram of the local structure of the lead screw provided in the embodiment of the present application is shown Figure 1 ;

[0016] Figure 4 The schematic diagram of the local structure of the lead screw provided in the embodiment of the present application is shown Figure 2 ;

[0017] Figure 5 A schematic diagram of the three-dimensional structure of the movable sleeve and the limiting screw provided in an embodiment of the present application is shown;

[0018] Figure 6 A curve diagram showing the relationship between the extension and contraction amount L of the pull rope provided in an embodiment of the present application and the time T.

[0019] Icons: 1. Housing; 101. Threading hole; 2. Bearing; 3. Long thread nut; 4. Permanent magnet; 5. Coil stator; 6. Planetary cage; 7. Roller; 8. Screw; 801. Through hole; 802. Mounting slot; 803. Sliding limiter; 9. Wire rope sensor; 901. Wire rope sensor body; 902. Wire rope; 10. Moving sleeve; 1001. Guide slot; 11. Limiting screw; 12. Spring; 13. Fixed pulley; 14. Drive circuit board; 15. End cover; 16. Guide seal; 17. Connector. DETAILED DESCRIPTION

[0020] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on this application.

[0021] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0022] In this application, unless otherwise specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they can refer to fixed connection, detachable connection, or integral connection; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0023] Currently, servo cylinders use a servo motor, coupled to a synchronous belt or directly to a coupling, to drive a ball screw, achieving precise control of linear motion. To detect the force applied to the cylinder's output, a pressure sensor is typically added. Because the pressure sensor cable must be connected to and follow the cylinder's output, a certain length of sensor cable must be left outside the servo cylinder. Exposed sensor cable is susceptible to damage.

[0024] Based on this, the following embodiment of the present application proposes a linear servo electric cylinder, in which a pull rope sensor is fixedly installed at the rear end of the shell, and the pull rope output from the pull rope sensor passes through the roller screw transmission structure and enters the movable sleeve, and passes through the fixed pulley in the movable sleeve and is fixedly connected to the other end of the roller screw transmission structure through the end cover, so that the entire pull rope sensor is set in the shell of the linear servo electric cylinder, and there is no need to reserve a sensor cable outside the servo electric cylinder. During measurement, the sensor cable will no longer move with the output end of the electric cylinder, and the exposed sensor cable is avoided from being easily damaged.

[0025] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and embodiments.

[0026] Example

[0027] See also Figure 1 The schematic diagram of the linear servo cylinder is shown in Figure 2 shown Figure 1 A partial enlarged schematic diagram, this embodiment proposes a linear servo electric cylinder, including: a housing 1, a bearing 2, a roller screw transmission structure as a rotor, a coil stator 5, a movable sleeve 10, a spring 12 and a fixed pulley 13.

[0028] The coil stator 5 is fixed on the inner side of the housing 1 , and an end cover 15 is provided at the front end of the housing 1 .

[0029] The roller screw transmission structure is located on the inner side of the coil stator 5 and is rotatably connected to the housing 1 through the bearing 2. One end of the roller screw transmission structure is located inside the housing 1, and the other end of the roller screw transmission structure passes through the end cover 15 and is located outside the housing 1. The movable sleeve 10 is slidably connected to the other end of the roller screw transmission structure through the end cover 15.

[0030] The spring 12 is connected to the inner bottom end of the movable sleeve 10 and the other end of the roller screw transmission structure passing through the end cover 15 respectively.

[0031] The fixed pulley 13 is fixed to the inner bottom end of the movable sleeve 10 , and the fixed pulley 13 is located inside the spring 12 .

[0032] The pull rope sensor 9 is fixedly mounted on the inner end face of the rear end of the housing 1. The pull rope 902 output from the pull rope sensor 9 passes through the roller screw transmission structure and enters the movable sleeve 10. After passing through the fixed pulley 13 in the movable sleeve 10, it is fixedly connected to the other end of the roller screw transmission structure through the end cover 15.

[0033] like Figure 1 As shown, the roller screw transmission structure includes: a long thread nut 3, a planetary retainer 6, rollers 7 and a screw 8.

[0034] The long-threaded nut 3 is located inside the shell 1 and is rotatably connected to the shell 1 through the bearing 2; a permanent magnet 4 is fixedly provided on the outer peripheral side of the long-threaded nut 3, and the position of the permanent magnet 4 corresponds to that of the coil stator 5, and the permanent magnet 4 is located on the inner side of the coil stator 5.

[0035] The permanent magnet 4 is composed of a plurality of permanent magnet sheets, each of which is clamped on the outer peripheral side of the long thread nut 3. Optionally, the permanent magnet sheets are made of neodymium iron boron permanent magnets, which can provide the maximum motor torque.

[0036] One end of the lead screw 8 is located inside the long thread nut 3, the planetary cage 6 is arranged on the circumference of the lead screw 8, the roller 7 is rotationally connected to the planetary cage 6, and the roller 7 is also threadedly connected to the lead screw 8 and the long thread nut 3 respectively.

[0037] The other end of the lead screw 8 passes through the end cover 15 and is slidably connected to the movable sleeve 10 .

[0038] The spring 12 is connected to the inner bottom end of the movable sleeve 10 and the polished rod portion of the lead screw 8 located outside the end cover 15 respectively.

[0039] The pull rope 902 output from the pull rope sensor 9 passes through the lead screw 8 and enters the movable sleeve 10 .

[0040] See also Figure 3 The local structure of the screw shown Figure 1 See also Figure 4 The local structure of the screw shown Figure 2 The linear servo electric cylinder proposed in this embodiment also includes: a guide seal 16 and a sliding limiter 803 .

[0041] The lead screw 8 includes: an integrally formed threaded portion and a polished rod portion; wherein the threaded portion is located on a side of the housing 1 away from the end cover 15 , and the polished rod portion is located on a side of the housing 1 close to the end cover 15 .

[0042] A planetary retainer 6 is provided on the outer circumferential surface of the threaded portion of the screw 8. The planetary retainer 6 is clearance-fitted with the threaded portion of the screw 8. Both ends of the roller 7 are rotatably connected to the planetary retainer 6. The middle part of the roller 7 is threadedly connected to the threaded portion of the screw 8 and the inner wall of the long threaded nut 3 respectively.

[0043] The smooth rod portion of the lead screw 8 passes through the end cover 15, and a guide seal 16 is provided between the smooth rod portion of the lead screw 8 and the end cover 15. A plurality of sliding limit portions 803 are evenly provided on the outer peripheral side of the smooth rod portion of the lead screw 8 located outside the end cover 15; the smooth rod portion of the lead screw 8 located outside the end cover 15 is slidingly connected to the movable sleeve 10 through the sliding limit portion 803.

[0044] Specifically, a through hole 801 is opened inside the lead screw 8 , and the through hole 801 passes through both ends of the lead screw 8 along the extension direction of the lead screw 8 .

[0045] The polished portion of the lead screw 8 outside the end cover 15 is provided with a mounting groove 802 .

[0046] The pull rope 902 passes through the through hole 801 of the lead screw 8 and enters the movable sleeve 10 . After passing through the fixed pulley 13 in the movable sleeve 10 , the pull rope 902 enters the installation groove 802 and is fixedly connected in the installation groove 802 .

[0047] Specifically, if Figure 1 As shown, the drawstring sensor 9 includes a drawstring sensor body 901 and a drawstring 902 .

[0048] The pull rope sensor body 901 is fixedly mounted on the inner end surface of the rear end of the housing 1. The pull rope 902 output from the pull rope sensor body 901 passes through the through hole 801 and enters the movable sleeve 10. After passing through the fixed pulley 13 in the movable sleeve 10, it is fixedly connected to the mounting groove 802.

[0049] See also Figure 5 The three-dimensional structural diagram of the movable sleeve and the limiting screw ring is shown. The movable sleeve 10 is sealed at one end away from the polished rod part, and a threaded groove is provided on the outer side wall of the end of the movable sleeve 10 connected to the polished rod part. Guide grooves 1001 are evenly provided on the side walls of the movable sleeve 10, and the extension direction of the guide grooves 1001 is the same as the extension direction of the movable sleeve 10.

[0050] The sliding limit portion 803 can be inserted into the guide groove 1001 so that the lead screw 8 can slide along the movable sleeve 10. When the movable sleeve 10 and the lead screw 8 move relative to each other, the guide groove 1001 of the movable sleeve 10 guides the lead screw 8.

[0051] The linear servo electric cylinder proposed in this embodiment further includes: a limiting screw 11 ; the thread groove of the movable sleeve is threadedly connected to the limiting screw 11 .

[0052] The linear servo electric cylinder proposed in this embodiment is characterized by further comprising: a driving circuit board 14;

[0053] A driving circuit board 14 is further provided on the inner end surface of the rear end of the housing 1 , and the coil stator 5 and the rope sensor 9 are both connected to the driving circuit board 14 .

[0054] like Figure 1 As shown, in the linear servo cylinder proposed in this embodiment, the housing 1 is further provided with a threading hole 101 for passing the wiring between the coil stator 5 and the driver circuit board 14. A connector 17 is also provided on the outside of the housing 1, and the connector 17 is connected to the driver circuit board 14.

[0055] When the linear servo electric cylinder starts working, when the lead screw 8 moves linearly and the movable sleeve 10 is not in contact with an object, the lead screw 8 moves linearly, and the pull rope 902 gradually extends along with the linearly moving lead screw 8. When the movable sleeve 10 contacts the object, the movable sleeve 10 no longer moves due to the obstruction of the object. Under the guiding effect of the movable sleeve 10 on the lead screw 8, relative movement occurs between the movable sleeve 10 and the lead screw 8, the spring is compressed, and the pull rope 902 retracts along with the compressed spring back to the pull rope sensor body 901 until the linear servo electric cylinder stops working.

[0056] See also Figure 6 The curve diagram shown is a graph of the relationship between the rope extension and contraction amount L and time T, wherein T1 represents the time point when the movable sleeve 10 contacts the object and the movable sleeve 10 no longer moves due to the obstruction of the object, and T2 represents the time point when the linear servo electric cylinder stops working.

[0057] Record the first extension L1 of the pull rope 902 from the start to the stop of the linear servo electric cylinder and the second extension L2 of the pull rope 902 when the movable sleeve 10 contacts the object and the movable sleeve 10 no longer moves due to the obstruction of the object.

[0058] The second extension amount L2 of the pull rope 902 when the movable sleeve 10 contacts the object and the movable sleeve 10 no longer moves due to the obstruction of the object is the second extension amount L2 of the pull rope 902 before the spring 12 is deformed.

[0059] The force applied to the linear servo electric cylinder is calculated based on the recorded first extension amount L1 and second extension amount L2.

[0060] Among them, L2-L1 is the deformation of the spring. Then, according to Hooke's law, the force F of the spring can be obtained as F=k(L2-L1), where k is the elastic coefficient of the spring, that is, the force F at the output end of the linear servo electric cylinder.

[0061] The linear servo electric cylinder provided in this embodiment can obtain the deformation of the spring using a pull-wire sensor, thereby deriving the magnitude of the force at the output end of the linear servo electric cylinder according to Hooke's law. It has a compact structure and reduces costs.

[0062] The linear servo electric cylinder provided in this embodiment also has the following characteristics:

[0063] The linear servo electric cylinder sets the roller screw transmission structure as the rotor of the linear servo motor inside the brushless servo motor, combining the roller screw transmission structure and the linear servo motor into one. The rotational motion of the linear servo motor rotor is directly converted into the linear motion of the screw through the rollers distributed around the screw in the roller screw transmission structure. This not only eliminates the original transmission mechanism between the roller screw transmission structure and the linear servo motor, improving the transmission efficiency, but also greatly reduces the size and weight of the electric cylinder.

[0064] To sum up, this embodiment proposes a linear servo electric cylinder, in which a pull rope sensor is fixedly installed at the rear end of the shell, and the pull rope output from the pull rope sensor passes through the roller screw transmission structure and then enters the movable sleeve, and passes through the fixed pulley in the movable sleeve and is fixedly connected to the other end of the roller screw transmission structure through the end cover. Compared with the related art that requires a certain length of sensor cable to be reserved outside the servo electric cylinder, and the sensor cable needs to move with the output end of the electric cylinder when detecting the force at the output end of the electric cylinder, the pull rope sensor is arranged as a whole in the shell of the linear servo electric cylinder. During measurement, the sensor cable does not need to move with the output end of the electric cylinder, and there is no need to reserve a sensor cable outside the servo electric cylinder, which avoids the situation where the exposed sensor cable is easily damaged.

[0065] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A linear servo electric cylinder, characterized in that: include: Housing, bearings, roller screw drive structure as rotor, coil stator, moving sleeve, spring and fixed pulley; The coil stator is fixed on the inner side of the shell, and an end cover is provided at the front end of the shell; The roller screw transmission structure is located on the inner side of the coil stator and is rotatably connected to the housing through a bearing. One end of the roller screw transmission structure is located inside the housing, and the other end of the roller screw transmission structure passes through the end cover and is located outside the housing. The movable sleeve is slidably connected to the other end of the roller screw transmission structure that passes through the end cover. The spring is respectively connected to the inner bottom end of the movable sleeve and the other end of the roller screw transmission structure passing through the end cover; The fixed pulley is fixed to the inner bottom end of the movable sleeve, and the fixed pulley is located inside the spring; The draw rope sensor is fixedly mounted on the inner end face of the rear end of the housing. The draw rope output from the draw rope sensor passes through the roller screw transmission structure and enters the movable sleeve. After passing through the fixed pulley in the movable sleeve, the draw rope is fixedly connected to the other end of the roller screw transmission structure passing through the end cover.

2. The linear servo electric cylinder according to claim 1, characterized in that: A roller screw transmission structure comprising: a long thread nut, a planetary cage, rollers and a screw; The long-threaded nut is located inside the housing and is rotatably connected to the housing via a bearing; a permanent magnet is fixedly provided on the outer periphery of the long-threaded nut, and the position of the permanent magnet corresponds to the position of the coil stator, and the permanent magnet is located on the inner side of the coil stator; One end of the lead screw is located inside the long-threaded nut, a planetary cage is arranged on the circumference of the lead screw, the roller is rotatably connected to the planetary cage, and the roller is also threadedly connected to the lead screw and the long-threaded nut respectively; The other end of the lead screw passes through the end cover and is slidably connected to the moving sleeve; The spring is respectively connected to the inner bottom end of the movable sleeve and the polished rod portion of the lead screw located outside the end cover; The pull rope output from the pull rope sensor passes through the lead screw and enters the moving sleeve.

3. The linear servo electric cylinder according to claim 2, characterized in that: Also includes: Guide seal and sliding limiter; The lead screw comprises: an integrally formed threaded portion and a polished rod portion; wherein the threaded portion is located on a side of the housing away from the end cap, and the polished rod portion is located on a side of the housing close to the end cap; A planetary cage is provided on the outer circumferential surface of the threaded portion of the screw. The planetary cage is clearance-fitted with the threaded portion of the screw. Both ends of the roller are rotatably connected to the planetary cage. The middle portion of the roller is threadedly connected to the threaded portion of the screw and the inner wall of the long-threaded nut respectively. The polished rod portion of the lead screw passes through the end cover, a guide seal is provided between the polished rod portion of the lead screw and the end cover, and a plurality of sliding limit portions are evenly provided on the outer peripheral side of the polished rod portion of the lead screw outside the end cover; the polished rod portion of the lead screw outside the end cover is slidably connected to the movable sleeve through the sliding limit portion.

4. The linear servo electric cylinder according to claim 2, characterized in that: A through hole is provided inside the lead screw, and the through hole passes through both ends of the lead screw along the extension direction of the lead screw; The smooth rod portion of the lead screw located outside the end cover is provided with a mounting groove; The pull rope passes through the through hole of the lead screw and enters the movable sleeve, passes through the fixed pulley in the movable sleeve and enters the installation groove, and is fixedly connected in the installation groove.

5. The linear servo electric cylinder according to claim 4, characterized in that: The draw rope sensor includes: a draw rope sensor body and a draw rope; The pull rope sensor body is fixedly mounted on the inner end surface of the rear end of the shell. The pull rope output from the pull rope sensor body passes through the through hole and enters the movable sleeve. After passing through the fixed pulley in the movable sleeve, it is fixedly connected to the mounting groove.

6. The linear servo electric cylinder according to claim 3, characterized in that: The end of the movable sleeve away from the polished rod portion is sealed, and a threaded groove is provided on the outer side wall of the end portion of the movable sleeve connected to the polished rod portion. Guide grooves are evenly provided on the side wall of the movable sleeve, and the extension direction of the guide grooves is the same as the extension direction of the movable sleeve. The sliding limit portion can be inserted into the guide groove, so that the lead screw can slide along the movable sleeve. When the movable sleeve and the lead screw move relative to each other, the guide groove of the movable sleeve guides the lead screw.

7. The linear servo electric cylinder according to claim 3, characterized in that: Also includes: Limiting screw; The thread groove of the movable sleeve is threadably connected to the limiting screw ring.

8. The linear servo electric cylinder according to claim 1, characterized in that: Also includes: Driver circuit board; A driving circuit board is also provided on the inner end surface of the rear end of the shell, and the coil stator and the pull rope sensor are both connected to the driving circuit board.

9. The linear servo electric cylinder according to claim 1, characterized in that: When the linear servo electric cylinder starts working, when the lead screw moves linearly and the moving sleeve is not in contact with the object, the lead screw moves linearly, and the pull rope will gradually extend along with the linearly moving lead screw. When the moving sleeve contacts the object, the moving sleeve will no longer move due to the obstruction of the object. Under the guiding effect of the moving sleeve on the lead screw, relative movement occurs between the moving sleeve and the lead screw, the spring is compressed, and the pull rope will retract along with the compressed spring into the rope sensor body until the linear servo electric cylinder stops working; Record the first extension of the rope from the start of the linear servo electric cylinder to the stop of the linear servo electric cylinder, and the second extension of the rope when the movable sleeve contacts the object and the movable sleeve no longer moves due to the obstruction of the object; The force applied to the linear servo electric cylinder is calculated based on the recorded first extension amount and second extension amount.

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