Hollow double-output-shaft servo planetary roller screw electric cylinder

Abstract

This application relates to the field of electric cylinders, and more particularly to a hollow dual-output-shaft servo planetary roller screw electric cylinder, comprising a housing, a planetary screw, a screw nut, and an encoder. A servo motor stator is housed within the housing. The screw nut is rotatably connected to the housing, and a permanent magnet is fixed to the outer peripheral wall of the screw nut to serve as the servo motor rotor. The screw nut has a through-channel at its center, and the planetary screw is threaded into the channel. Output shafts are fixedly connected to both ends of the planetary screw, and the two output shafts exit from both ends of the housing via the channel. The encoder is a hollow annular structure, fitted onto the screw nut and coaxially arranged with it. The encoder is either a capacitive encoder or a photoelectric encoder. Compared to Hall effect magnetic sensing, capacitive or photoelectric encoders offer higher detection accuracy, faster response, and stronger interference resistance.

Description

Technical Field

[0001] This application relates to the field of electric cylinders, and more particularly to a hollow double-output shaft servo planetary roller screw electric cylinder. Background Technology

[0002] An electric cylinder, also known as an electric cylinder, is an actuation device that converts electrical energy into linear displacement. It is widely used in fields such as automation equipment, aerospace, robotics, and precision manufacturing. To achieve position feedback and control during the actuation process, electric cylinders are typically equipped with encoders.

[0003] In related technologies, since most existing encoders are solid structures, they are mostly used in electric cylinders with a single output shaft.

[0004] For some electric cylinders with dual output shafts, the function of the encoder used in them often depends on an additional reverse mechanism, such as the dual-head electric cylinder disclosed in patent document CN217904191U. In this solution, the position needs to be transmitted to the encoder outside the motor through the synchronous pulley box and synchronous belt. Not only is the feedback path long, but the structure is also complex and the dynamic response is slow, which cannot meet the application scenarios of high-frequency precision control.

[0005] Of course, some electric cylinders use the original Hall effect magnet structure to achieve position detection. For details, please refer to the actuation system disclosed in announcement number CN207200476U. However, although the Hall effect magnet structure is inexpensive, it has problems such as poor detection accuracy, slow response, and weak anti-interference, making it difficult to meet the needs of high-end servo control. Utility Model Content

[0006] In order to solve at least one of the technical problems mentioned in the background art, the purpose of this application is to provide a hollow double-output shaft servo planetary roller screw electric cylinder.

[0007] To achieve the above objectives, this application provides the following technical solution.

[0008] A hollow dual-output-shaft servo planetary roller screw electric cylinder includes a housing, a planetary screw, a screw nut, and an encoder. A servo motor stator is housed within the housing. The screw nut is rotatably connected to the housing, and a permanent magnet is fixed to the outer peripheral wall of the screw nut to serve as the servo motor rotor. The screw nut has a through-channel at its center, and the planetary screw is threaded into the channel. Output shafts are fixedly connected to both ends of the planetary screw, and the two output shafts exit from both ends of the housing through the channel. The encoder is a hollow annular structure, fitted onto the screw nut and coaxially arranged with it. The encoder is either a capacitive encoder or a photoelectric encoder.

[0009] As an optional embodiment of this application, the electric cylinder further includes a guide mechanism, under the guidance of the guide mechanism, the output shaft can move axially relative to the housing and maintain relative positioning with the housing in the circumferential direction.

[0010] As an optional embodiment of this application, the guiding mechanism includes a sliding sleeve and a guide rod; one of the guide rod and the sliding sleeve is fixed to the output shaft, and the other is fixed to the housing; the guide rod slides along the axial direction of the planetary screw on the sliding sleeve.

[0011] As an optional embodiment of this application, the two ends of the lead screw nut are rotatably connected to the housing via two bearings.

[0012] As an optional embodiment of this application, the bearing is a roller bearing.

[0013] As an optional embodiment of this application, at least one of the two output shafts has a lifting lug fixed to its end; or, one of the output shafts is connected to a hydraulic cylinder.

[0014] Compared with the prior art, this application has the following advantages:

[0015] Compared to Hall effect magnetic sensing, capacitive encoders or photoelectric encoders offer higher detection accuracy, faster response, and stronger resistance to interference.

[0016] In addition, in this application, since the encoder used is a hollow ring structure, it can be fitted onto the lead screw nut. Compared with the traditional ordinary encoder that relies on the synchronous belt and other reverse mechanisms, it can directly act on the lead screw nut, thereby shortening the feedback path and simplifying the structure of the entire electric cylinder, making the structure of the entire electric cylinder more compact.

[0017] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this application, nor is it intended to limit the scope of this application. Other features of this application will become readily apparent from the following description. Attached Figure Description

[0018] The above and other objects, features, and advantages of exemplary embodiments of this application will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings. Several embodiments of this application are illustrated in the drawings by way of example and not limitation, in which:

[0019] In the accompanying drawings, the same or corresponding reference numerals indicate the same or corresponding parts.

[0020] Figure 1 A schematic diagram of the structure of this application is shown. Figure 1 ;

[0021] Figure 2 An axial cross-sectional view of this application is shown;

[0022] Figure 3 A schematic diagram of the structure of this application is shown. Figure 2 (Features lifting lugs);

[0023] Figure 4 A schematic diagram of the structure of this application is shown. Figure 3 (Equipped with a hydraulic cylinder).

[0024] Explanation of the labels in the diagram:

[0025] 1. Housing; 11. Servo motor stator; 12. Roller bearing;

[0026] 2. Lead screw nut; 21. Permanent magnet; 22. Channel;

[0027] 3. Planetary lead screw; 31. Output shaft; 311. Lifting lug; 312. Hydraulic cylinder;

[0028] 4. Encoder;

[0029] 5. Guiding mechanism; 51. Guide rod; 52. Sliding sleeve; 53. Connecting plate. Detailed Implementation

[0030] To make the objectives, features, and advantages of this application more apparent and understandable, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0031] Reference Figures 1-4 As shown, this embodiment provides a hollow double-output shaft servo planetary roller screw electric cylinder (hereinafter referred to as electric cylinder), which includes a housing 1, a planetary screw 3, a screw nut 2, and an encoder 4.

[0032] like Figure 2 As shown, a servo motor stator 11 is provided inside the housing 1. The two ends of the lead screw nut 2 are rotatably connected to the housing 1 through two roller bearings 12. A permanent magnet 21 is fixed on the outer peripheral wall of the lead screw nut 2 to serve as the servo motor rotor. In other words, the permanent magnet 21 and the lead screw nut 2 together serve as the rotor of the servo motor. Thus, the servo motor rotor and the servo motor stator 11 together form the servo motor structure. When powered on, the servo motor rotor (lead screw nut 2) can rotate relative to the servo motor stator 11 in the housing 1. In this embodiment, the planetary lead screw 3 is a planetary roller lead screw.

[0033] The lead screw nut 2 has a through channel 22 at its center. The channel 22 is coaxial with the lead screw nut 2. The inner circumferential wall of the channel 22 is threaded. Based on this thread, the planetary lead screw 3 is threadedly engaged in the channel 22, that is, the planetary lead screw 3 is threadedly engaged with the lead screw nut 2. The planetary lead screw 3 is coaxial with the channel 22. When the lead screw nut 2 and the planetary lead screw 3 rotate relative to each other, the planetary lead screw 3 can move axially relative to the lead screw nut 2 in the channel 22.

[0034] Both ends of the planetary screw 3 are fixedly connected to output shafts 31. Both output shafts 31 are coaxially arranged with the planetary screw 3 and located in the channel 22. The two output shafts 31 move out from both ends of the housing through the channel 22.

[0035] The two output shafts 31 are equivalent to two force-applying ends, enabling the electric cylinder to be driven in both directions. One or both output shafts 31 can be selected as the power output end according to actual needs.

[0036] The encoder 4 is mainly used for position detection and control during actuation of the electric cylinder. In this embodiment, the encoder 4 is a hollow annular structure, such as a circular ring encoder 4. The encoder 4 is housed inside the housing 1 and passes through its own annular hole onto the outer peripheral wall of the lead screw nut 2, coaxially arranged with the lead screw nut 2. The encoder 4 can be a capacitive encoder or a photoelectric encoder, as is common in the prior art. This type of encoder 4 mainly includes two relatively rotatable components. Position detection is achieved by detecting the relative rotation angle of the two components. Specifically, in this embodiment, one of the two components of the encoder 4 is fixed to the housing 1, and the other is fixed to the lead screw nut 2, rotating synchronously and coaxially with the lead screw nut 2. Thus, the encoder 4 can detect parameters such as the rotation angle of the lead screw nut 2, thereby achieving position detection of the electric cylinder. Specific applications and descriptions of this type of encoder 4 in the prior art will not be elaborated upon here.

[0037] Compared to Hall effect magnetic sensing, capacitive encoders or photoelectric encoders offer higher detection accuracy, faster response, and stronger resistance to interference.

[0038] In addition, in this embodiment, since the encoder 4 used is a hollow ring structure, it can be fitted onto the lead screw nut 2. Compared with the conventional encoder 4 that relies on the synchronous belt and other reverse mechanisms, it can directly act on the lead screw nut 2, thereby shortening the feedback path and simplifying the structure of the entire electric cylinder, making the structure of the entire electric cylinder more compact.

[0039] In addition, to prevent the lead screw nut 2 from causing the planetary lead screw 3 to rotate along with it when rotating, in some embodiments, such as Figure 1As shown, the electric cylinder also includes a guide mechanism 5. Under the guidance of the guide mechanism 5, the output shaft 31 can move axially relative to the housing 1 and maintain relative positioning with the housing 1 in the circumferential direction. This circumferential relative positioning can be understood as the output shaft 31 being unable to rotate circumferentially relative to the housing 1, so that the output shaft 31 can only move linearly along the axial direction, which in turn limits the planetary screw 3 to only move linearly along the axial direction and prevents circumferential rotation. Thus, when energized, the housing remains stationary, and the screw nut 2 rotates inside the housing, thereby driving the planetary screw 3 to move axially, thus driving the two output shafts 31 to move synchronously in the same direction.

[0040] As a specific implementation method, such as Figure 1 As shown, the guiding mechanism 5 includes a sliding sleeve 52 and a guide rod 51. The number of guide rods 51 and sliding sleeves 52 can be selected according to actual needs. For example, in this embodiment, two guide rods 51 are used in conjunction with two sets of sliding sleeves 52. Each set of sliding sleeves 52 can be one or more. The two guide rods 51 are respectively located on both sides of the output shaft 31. Specifically, a connecting plate 53 is fixed on one of the output shafts 31. The guide rod 51 extends along the axial direction of the output shaft 31, and one end of the guide rod 51 is fixed on the connecting plate 53. The sliding sleeve 52 is fixed on the outer wall of the housing 1. The guide rod 51 slides through the sliding sleeve 52 to guide the axial movement of the output shaft 31 and prevent the output shaft 31 from deflecting.

[0041] It is worth noting that the positions of the output shaft 31 and the sliding sleeve 52 can also be interchanged. For example, the output shaft 31 can be fixed on the housing 1, and the sliding sleeve 52 can be fixed on the output shaft 31, which can also serve as a guide.

[0042] In some embodiments, such as Figure 3 As shown, at least one of the two output shafts 31 has a lifting lug 311 fixed at its end. For example, in this embodiment, both output shafts 31 are provided with lifting lugs 311 at their ends. The lifting lugs 311 are used to connect the load structure or hook assembly and can be used to suspend and precisely lift the load, which is suitable for automatic gripping and intelligent handling equipment.

[0043] In some other alternative implementations, such as Figure 4 As shown, a hydraulic cylinder 312 can be connected to one of the output shafts 31. Specifically, the end of the output shaft 31 is fixed to the piston of the hydraulic cylinder 312. The piston is controlled by an electric cylinder to move forward / backward in the piston cylinder of the hydraulic cylinder 312 to achieve closed-loop pressure control, which is suitable for pneumatic-hydraulic integrated servo devices.

[0044] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this application can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this application can be achieved, and this is not limited herein.

[0045] 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 technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0046] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A hollow double-output-shaft servo planetary roller screw electric cylinder, characterized in that, The device includes a housing, a planetary lead screw, a lead screw nut, and an encoder. The housing houses a servo motor stator. The lead screw nut is rotatably connected to the housing, and a permanent magnet is fixed to the outer peripheral wall of the lead screw nut to serve as the servo motor rotor. The lead screw nut has a through-channel at its center, and the planetary lead screw is threaded into the channel. Output shafts are fixedly connected to both ends of the planetary lead screw, and the two output shafts pass through the channel from both ends of the housing. The encoder is a hollow annular structure, fitted onto the lead screw nut and coaxially arranged with it. The encoder is either a capacitive encoder or a photoelectric encoder.

2. The hollow double-output-shaft servo planetary roller screw electric cylinder according to claim 1, characterized in that, The electric cylinder also includes a guide mechanism, under the guidance of the guide mechanism, the output shaft can move axially relative to the housing and maintain relative positioning with the housing in the circumferential direction.

3. A hollow double-output-shaft servo planetary roller screw electric cylinder according to claim 2, characterized in that, The guiding mechanism includes a sliding sleeve and a guide rod; one of the guide rod and the sliding sleeve is fixed to the output shaft, and the other is fixed to the housing; the guide rod slides along the axial direction of the planetary screw on the sliding sleeve.

4. A hollow double-output-shaft servo planetary roller screw electric cylinder according to claim 1, characterized in that, The two ends of the lead screw nut are rotatably connected to the machine housing via two bearings.

5. A hollow double-output-shaft servo planetary roller screw electric cylinder according to claim 4, characterized in that, The bearing is a roller bearing.

6. A hollow double-output-shaft servo planetary roller screw electric cylinder according to claim 1, characterized in that, At least one of the two output shafts has a lifting lug fixed to its end; or, one of the output shafts is connected to a hydraulic cylinder.

Images