A damped reversing electric cylinder

Abstract

This utility model discloses a damped reversing electric cylinder, comprising: a motor, a reducer, an outer tube assembly, a lead screw, a nut, a bearing housing assembly, and a push rod; the motor and reducer are drivenly connected, the output shaft of the reducer is drivenly connected to the lead screw, the bearing housing assembly is wrapped around the outside of the lead screw and installed between the reducer and the outer tube assembly; the nut is installed on the lead screw to form a lead screw-nut pair, the outer tube assembly is sleeved on the outside of the lead screw-nut pair, the outer tube assembly has a rotational limit on the nut, and the nut can move axially along the outer tube assembly; one end of the push rod is connected to the nut, and the other end extends out from inside the outer tube assembly to the outside; at least one end of the outer tube assembly is provided with a damper, the damper being used to apply damping to the axial movement of the nut. This utility model can apply a controllable damping force to the axial movement of the nut at at least one reversing instant of the electric cylinder.

Description

Technical Field

[0001] This utility model belongs to the field of electric cylinder technology, and in particular relates to a damped reversing electric cylinder. Background Technology

[0002] Electric cylinders, as electromechanical actuators that convert the rotary motion of a servo motor into precise linear motion, are increasingly replacing traditional hydraulic or pneumatic cylinders in industrial automation, engineering machinery, and medical devices due to their advantages such as energy saving, high control precision, and fast response speed. Their basic working principle involves a motor driving a lead screw and nut pair to convert rotary motion into linear motion of a push rod, thereby outputting the required thrust and displacement. However, under conditions of high-frequency reversing, long stroke, or large inertia loads, the enormous inertial force accumulated in the moving parts (such as the nut and its connected push rod, and the external load) during start-up, stopping, and especially instantaneous reversing, transforms into a strong impact load. This impact not only causes severe vibration and noise in the entire transmission system (including the lead screw and nut), affecting positioning accuracy and equipment stability, but also significantly accelerates the wear and fatigue of transmission components, shortening the service life of the electric cylinder.

[0003] The mainstream solutions for mitigating the impact problem of electric cylinders in existing technologies mainly fall into three categories: First, improving structural rigidity, such as using integral cast shells, adding reinforcing ribs, or upgrading to high-load-bearing components like planetary roller screws to enhance overall deformation resistance; second, optimizing the materials of key components, such as using high-strength alloy steel and heat-treating it to enhance its wear resistance and toughness; and third, adding buffer devices inside or at the end of the system, such as integrating polyurethane buffer pads or disc springs at the end of the push rod, or designing pre-compressed spring groups internally, in order to absorb energy through slight deformation or displacement during overload. Although these solutions can alleviate the problem to some extent, they all have significant limitations: strengthening rigidity and optimizing materials significantly increase manufacturing costs and equipment weight; while internal buffer structures are usually complex in design, which may reduce the system's response speed and make maintenance inconvenient. More importantly, conventional end buffers are mainly aimed at the extreme impact at the end of the stroke, and have limited effect on suppressing axial vibration caused by load inertia during reversing, making it difficult to effectively offset the impact force generated by inertia of moving parts at the moment of reversing. Therefore, designing a device with a relatively simple structure that does not affect the system response speed and can effectively suppress axial impact caused by load inertia or moment of inertia during the reversing process has become a key technical challenge for improving the dynamic performance, operational stability and service life of electric cylinders. Utility Model Content

[0004] The technical problem to be solved by this utility model is to provide a damped reversing electric cylinder that addresses the shortcomings of the prior art. It can apply a controllable damping force to the axial movement of the nut at at least one reversing moment of the electric cylinder, thereby offsetting and dissipating most of the impact kinetic energy generated by the load inertia, converting harmful mechanical energy into other forms of energy dissipation, and thus directly suppressing the severe vibration and impact of the transmission system (especially the lead screw and nut pair).

[0005] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is: a damped reversing electric cylinder, comprising: a motor, a reducer, an outer tube assembly, a lead screw, a nut, a bearing housing assembly, and a push rod; the motor and the reducer are connected by transmission, the output shaft of the reducer is connected by transmission to the lead screw, the bearing housing assembly is wrapped around the outside of the lead screw and installed between the reducer and the outer tube assembly; the nut is installed on the lead screw to form a lead screw-nut pair, the outer tube assembly is sleeved on the outside of the lead screw-nut pair, the outer tube assembly has a rotational limit on the nut, and the nut can move axially along the outer tube assembly; one end of the push rod is connected to the nut, and the other end extends out from inside the outer tube assembly to the outside; at least one end of the outer tube assembly is provided with a damper, the damper being used to dampen the axial movement of the nut.

[0006] In the aforementioned damped reversing electric cylinder, dampers are provided at both ends of the outer tube assembly, and the dampers are located inside the outer tube assembly.

[0007] The damped reversing electric cylinder described above includes a damper comprising a fixed pressure ring, a spring, and a movable pressure ring. The fixed pressure ring and the movable pressure ring are respectively clamped at both ends of the spring, and the movable pressure ring is used to abut against the end of the nut.

[0008] In the aforementioned damped reversing electric cylinder, one end of the outer tube assembly is fixed to the connecting seat of the bearing housing assembly, and the other end of the outer tube assembly is connected to the flange. One of the dampers' retaining rings is fixed to the connecting seat, and the other damper's retaining ring is fixed to the flange.

[0009] In the aforementioned damped reversing electric cylinder, the inner ring side of the flange is provided with a seal that contacts the rod body of the push rod. The aforementioned damped reversing electric cylinder includes an outer tube assembly comprising an outer tube and a guide rail mounted on the inner side of the outer tube. The nut has a groove that cooperates with the guide rail, and the nut can move along the guide rail. The guide rail is parallel to the axis of the outer tube. Compared with the prior art, this invention has the following advantages: It can apply a controllable damping force to the axial movement of the nut at at least one reversing instant in the electric cylinder. This damping force effectively counteracts and dissipates most of the impact kinetic energy generated by load inertia, converting harmful mechanical energy into other forms of energy dissipation, thereby directly suppressing the severe vibration and impact of the transmission system (especially the lead screw and nut pair). This not only significantly improves the operational stability of the electric cylinder under high-speed, high-frequency reversing conditions and avoids positioning accuracy errors caused by impact, but also significantly reduces the peak stress and fatigue damage borne by key transmission components (such as the lead screw and nut), thereby extending the service life of the electric cylinder. Compared with existing technologies that strengthen overall rigidity or add complex internal buffer structures, the damper solution of this utility model has a simpler and more compact structure. It does not require complex modifications to the core transmission components of the electric cylinder, thus avoiding the increase in weight and cost caused by strengthening rigidity, as well as the problems of reduced response speed and inconvenient maintenance that may be caused by built-in complex buffer mechanisms. It achieves effective improvement of the electric cylinder's impact resistance and reliability with lower cost and simpler structure while ensuring efficient response and high-precision control.

[0010] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the structure of this utility model.

[0012] Figure 2 for Figure 1 A schematic diagram of the structure after removing the outer tube assembly.

[0013] Figure 3 This is a cross-sectional structural diagram of the present invention.

[0014] Figure 4 This is a schematic diagram of the damper of this utility model.

[0015] Explanation of reference numerals in the attached figures: 1—Motor; 2—Reducer; 3—Outer tube assembly; 4—Lead screw; 5—Nut; 6—Bearing housing assembly; 7—Push rod; 8—Damper; 9—Connecting seat; 10—Flange; 8-1—Fixing ring; 8-2—Spring; 8-3—Moving pressure ring. Detailed Implementation

[0016] like Figures 1-4As shown, a damped reversing electric cylinder includes: a motor 1, a reducer 2, an outer tube assembly 3, a lead screw 4, a nut 5, a bearing housing assembly 6, and a push rod 7; the motor 1 and the reducer 2 are connected in a driving relationship, the output shaft of the reducer 2 is connected in a driving relationship with the lead screw 4, the bearing housing assembly 6 is wrapped around the outside of the lead screw 4 and installed between the reducer 2 and the outer tube assembly 3; the nut 5 is installed on the lead screw 4 to form a lead screw 4-nut 5 pair, the outer tube assembly 3 is sleeved on the outside of the lead screw 4-nut 5 pair, the outer tube assembly 3 has a rotational limit on the nut 5, and the nut 5 can move axially along the outer tube assembly 3; one end of the push rod 7 is connected to the nut 5, and the other end extends out from inside the outer tube assembly 3 to the outside; at least one end of the outer tube assembly 3 is provided with a damper 8, the damper 8 is used to dampen the axial movement of the nut 5.

[0017] In implementation, motor 1 is typically a servo motor 1 or a stepper motor 1, connected to the input shaft of reducer 2 via flange 10. The motor 1 shaft is inserted into the keyway of the input hole of reducer 2 and secured with bolts to achieve power transmission. Reducer 2 is a planetary gear reducer 2 or a worm gear reducer 2, and its output shaft is fixedly connected to one end of lead screw 4 via a coupling. The coupling uses an elastic sleeve or diaphragm structure to compensate for installation errors. Lead screw 4 is a ball screw 4 or a trapezoidal lead screw 4, with a hardened surface. The thread of lead screw 4 mates with the internal thread of nut 5, forming a lead screw 4 and nut 5 pair. Bearing housing assembly 6 consists of bearing housing housing, rolling bearings, and sealing rings. The bearing housing housing is connected to the reducer 2 housing via bolts, and the other end is connected to the outer tube assembly 3 via a flange. The rolling bearing inside bearing housing assembly 6 supports lead screw 4, allowing lead screw 4 to rotate freely and bear axial loads. Nut 5 is made of bronze or engineering plastic, and the outer circle of nut 5 is machined with a keyway or flat surface for mating with the guide structure of outer tube assembly 3. The outer tube assembly 3 is a cylindrical structure made of steel or aluminum alloy. It is fitted around the outside of the lead screw 4 and nut 5. One end of the outer tube assembly 3 is connected to the bearing housing assembly 6, and the other end is open for the push rod 7 to extend out. The outer tube assembly 3 provides rotational limitation for the nut 5, for example, by installing a linear guide or key on the inner wall of the outer tube assembly 3, and providing a corresponding groove on the outer circumference of the nut 5, allowing the nut 5 to move only along the axial direction of the outer tube assembly 3 and preventing rotation. The push rod 7 is a steel rod. One end of the push rod 7 is connected to the nut 5 via a thread or pin, and the other end of the push rod 7 is machined with external threads or a ball head for connecting external loads.

[0018] A damper 8 is provided at least one end of the outer tube assembly 3. The damper 8 is installed inside the end of the outer tube assembly 3 and can be a hydraulic damper 8 or a mechanical spring 8-2 damper 8. Taking the mechanical spring 8-2 damper 8 as an example, the damper 8 includes a fixed pressure ring 8-1 and a movable pressure ring 8-3. The fixed pressure ring 8-1 can be fixed to the inner wall of the outer tube assembly 3 by welding or bolting, or it can be fixed to the connection structure at both ends of the outer tube assembly 3. The movable pressure ring 8-3 is connected to the spring 8-2, and the end of the movable pressure ring 8-3 maintains a certain gap with the end face of the nut 5. When the nut 5 moves axially and approaches the end of the outer tube assembly 3, the end of the nut 5 contacts the movable pressure ring 8-3, compressing the spring 8-2 and generating a damping force. The stiffness of the spring 8-2 of the damper 8 is selected according to the load weight and the speed of movement. For example, the preload of the spring 8-2 is set to the range of 50 Newtons to 200 Newtons to ensure smooth deceleration.

[0019] In operation, motor 1 receives a controller signal and starts, driving reducer 2 to output torque, which in turn rotates lead screw 4. The rotational motion of lead screw 4 is converted into linear motion of nut 5. Due to the rotational limitation of outer tube assembly 3, nut 5 moves axially, pushing push rod 7 to extend or retract. When push rod 7 moves rapidly and approaches the end of its stroke, the end of nut 5 contacts damper 8. Damper 8 absorbs kinetic energy and generates a reverse force through compression of spring 8-2, causing nut 5 to decelerate. For example, during the extension of push rod 7, nut 5 moves forward. When it approaches the front end of outer tube assembly 3, nut 5 presses against damper 8's moving pressure ring 8-3, spring 8-2 gradually compresses, damping force increases, push rod 7's speed decreases linearly, and eventually stops.

[0020] By incorporating damper 8, impact absorption and vibration suppression are achieved during the movement of the electric cylinder, resulting in smoother start-stop of push rod 7 and reduced component wear and noise generation. Simultaneously, the buffering effect of damper 8 improves the positioning accuracy and lifespan of the electric cylinder, making it suitable for high-frequency reversing applications.

[0021] In one scenario embodiment, this damped reversing electric cylinder is used in a feeding device of an automated production line. The feeding device needs to push metal workpieces from a conveyor belt into the machining position of a CNC machine tool. The electric cylinder's motor 1 is a servo motor 1, the reducer 2 has a transmission ratio of 10:1, and the lead screw 4 has a lead of 5 mm. The push rod 7 is connected to an aluminum alloy push plate, and the workpiece weighs 5 kg. When the controller sends a signal, the motor 1 rotates forward, the lead screw 4 rotates at a speed of 100 rpm, and the nut 5 drives the push rod 7 to extend at a speed of 500 mm / min. The push rod 7 pushes the workpiece forward, and when the workpiece approaches the machining position, the nut 5 moves to the front end of the outer tube assembly 3 and contacts the damper 8. The spring 8-2 of the damper 8 is compressed, generating a damping force of approximately 100 Newtons, causing the push rod 7 to decelerate uniformly in the last 10 mm of its stroke, and the workpiece gently contacts the machining position locating pin without rebound or deviation. Subsequently, the motor 1 reverses, and the nut 5 retracts. If a damper 8 is also provided at the rear end of the outer tube assembly 3, the retraction process is equally smooth. The entire feeding cycle is quiet and reliable, and the damper 8 enables efficient and shock-free automated operation.

[0022] In one embodiment, dampers 8 are provided at both ends of the outer tube assembly 3, and the dampers 8 are disposed inside the outer tube assembly 3.

[0023] In implementation, a damper 8 is installed inside the front and rear ends of the outer tube assembly 3. The dampers 8 have identical structures, both being mechanical spring 8-2 dampers 8. The fixing base of the front damper 8 is welded to the inner wall of the front end of the outer tube assembly 3, and the fixing base of the rear damper 8 is welded to the inner wall of the rear end of the outer tube assembly 3. The piston ends of the two dampers 8 maintain a 5 mm gap with the front and rear faces of the nut 5, respectively. When the nut 5 moves axially, regardless of the direction of movement, it will contact the corresponding damper 8 when approaching the end of the outer tube assembly 3.

[0024] During the extension of push rod 7, nut 5 moves forward and contacts the front damper 8; during the retraction of push rod 7, nut 5 moves backward and contacts the rear damper 8. The damper 8 generates damping force through the compression of spring 8-2, allowing nut 5 to decelerate smoothly in both directions. For example, in a feeding device, after push rod 7 extends to push material, motor 1 reverses, nut 5 retracts, and when it approaches the rear end of outer tube assembly 3, nut 5 contacts the rear damper 8, spring 8-2 is compressed, and push rod 7 retracts slowly, avoiding the impact caused by rapid return.

[0025] By setting dampers 8 at both ends of the outer tube assembly 3, uniform buffering of the bidirectional motion of the electric cylinder is achieved, avoiding motion imbalance that may be caused by single-end damping, and improving stability and reliability during commutation.

[0026] In one embodiment, the damper 8 includes a fixed pressure ring 8-1, a spring 8-2, and a movable pressure ring 8-3. The fixed pressure ring 8-1 and the movable pressure ring 8-3 are respectively clamped at both ends of the spring 8-2, and the movable pressure ring 8-3 is used to abut against the end of the nut 5.

[0027] In practice, the fixed pressure ring 8-1 is a ring-shaped steel component, fixed to the inner wall or end connection structure of the outer tube assembly 3 by bolts; the spring 8-2 is a compression spring 8-2, located between the fixed pressure ring 8-1 and the movable pressure ring 8-3; the movable pressure ring 8-3 is a sliding ring component, in contact with the end face of the nut 5. The outer diameter of the movable pressure ring 8-3 is slightly smaller than the inner diameter of the outer tube assembly 3, allowing it to move axially.

[0028] When nut 5 moves to its end point, the end of nut 5 pushes the movable pressure ring 8-3, compressing spring 8-2, while the fixed pressure ring 8-1 provides a reaction force. The stiffness of spring 8-2 is adjustable, for example, by replacing springs 8-2 of different specifications to adapt to different loads. In the feeding device, the fixed pressure ring 8-1 of the front damper 8 is fixed to the front end of the outer tube assembly 3 by bolts, and the movable pressure ring 8-3 contacts the front end face of nut 5; the rear damper 8 is similar. When push rod 7 extends, nut 5 pushes the front movable pressure ring 8-3, compressing spring 8-2, and the damping force gradually increases.

[0029] By using a combination of a fixed pressure ring 8-1, a spring 8-2, and a movable pressure ring 8-3, the damping force can be adjusted and evenly distributed, making the damping effect more controllable and improving installation convenience and maintainability.

[0030] In one embodiment, one end of the outer tube assembly 3 is fixed to the connecting seat 9 of the bearing seat assembly 6, and the other end of the outer tube assembly 3 is connected to the flange 10. One of the dampers 8 has a fixed pressure ring 8-1 fixed to the connecting seat 9, and the other damper 8 has a fixed pressure ring 8-1 fixed to the flange 10.

[0031] In practice, the connecting seat 9 is an extension of the bearing housing assembly 6 and is connected to one end of the outer tube assembly 3 by bolts; the flange 10 is an annular disc and is connected to the other end of the outer tube assembly 3 by bolts. The fixing ring 8-1 of the front damper 8 is fixed to the connecting seat 9 by bolts, and the fixing ring 8-1 of the rear damper 8 is fixed to the flange 10 by bolts.

[0032] The outer tube assembly 3 forms a closed structure through the connecting seat 9 and the flange 10, enhancing rigidity. In the feeding device, the connecting seat 9 is connected to the housing of the reducer 2, and the flange 10 seals the rear end of the outer tube assembly 3. The fixing ring 8-1 of the damper 8 is directly fixed to the connecting seat 9 and the flange 10, ensuring the stability of the damper 8. When the nut 5 moves, the damping force is transmitted to the connecting seat 9 or the flange 10 through the fixing ring 8-1, preventing loosening.

[0033] By connecting the damper 8 fixing ring 8-1 to the connecting seat 9 and flange 10, the damper 8 is securely installed, improving the overall structural rigidity and motion accuracy, and reducing vibration transmission.

[0034] In one embodiment, the inner ring side of the flange 10 is provided with a seal that contacts the body of the push rod 7. During implementation, the sealing element is a rubber sealing ring, which is embedded in the inner ring groove of the flange 10. The inner diameter of the sealing ring is slightly smaller than the diameter of the push rod 7, forming an interference fit. The sealing element is in continuous contact with the push rod 7, preventing external dust and liquid from entering the interior of the outer tube assembly 3.

[0035] During the movement of push rod 7, the seal slightly deforms as push rod 7 moves, maintaining the sealing effect. In the pusher device, flange 10 is installed at the rear end of outer tube assembly 3, and the seal protects the internal lead screw 4 and nut 5 from workshop dust contamination. For example, when push rod 7 retracts, the seal scrapes away impurities from the surface of push rod 7.

[0036] By incorporating seals, the internal components of the electric cylinder are protected from dust and contamination, improving their durability and lifespan in harsh environments.

[0037] In one embodiment, the outer tube assembly 3 includes an outer tube and a guide rail mounted on the inner side of the outer tube. The nut 5 has a groove that cooperates with the guide rail. The nut 5 is movable along the guide rail, and the guide rail is parallel to the axis of the outer tube.

[0038] During implementation, the outer tube is made of steel, and the guide rail consists of one or two parallel linear guide rails, which are fixed to the inner wall of the outer tube by bolts. The outer circumference of nut 5 is machined with a corresponding sliding groove, which is a T-shaped groove that mates with the T-shaped protrusion of the guide rail. The guide rail is precisely parallel to the axis of the outer tube, and a calibration tool is used during installation to ensure parallelism.

[0039] When the lead screw 4 rotates, the groove of the nut 5 slides along the guide rail, preventing the nut 5 from rotating and allowing only axial movement. In the pusher device, the guide rail length covers the entire stroke, and the gap between the nut 5 groove and the guide rail is 0.1 mm, ensuring smooth movement. For example, when the push rod 7 extends, the nut 5 moves forward in a straight line along the guide rail without deviation.

[0040] The cooperation of the guide rail and the slide groove enables precise linear guidance of nut 5, avoiding rotational errors and improving motion stability and positioning accuracy.

[0041] The above description is merely a preferred embodiment of the present utility model and does not constitute any limitation on the present utility model. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present utility model shall still fall within the protection scope of the present utility model.

Claims

1. A damped reversing electric cylinder, comprising: The device comprises a motor, a reducer, an outer tube assembly, a lead screw, a nut, a bearing housing assembly, and a push rod; the motor and reducer are connected by a drive mechanism, the output shaft of the reducer is connected to the lead screw by a drive mechanism, the bearing housing assembly is wrapped around the outside of the lead screw and installed between the reducer and the outer tube assembly; the nut is installed on the lead screw to form a lead screw-nut pair, the outer tube assembly is sleeved on the outside of the lead screw-nut pair, the outer tube assembly has a rotational limit on the nut, and the nut can move axially along the outer tube assembly; one end of the push rod is connected to the nut, and the other end extends out from inside the outer tube assembly to the outside; characterized in that at least one end of the outer tube assembly is provided with a damper, the damper being used to dampen the axial movement of the nut.

2. A damped reversing electric cylinder according to claim 1, characterized in that, Both ends of the outer tube assembly are equipped with dampers, which are located inside the outer tube assembly.

3. A damped reversing electric cylinder according to claim 2, characterized in that, The damper includes a fixed pressure ring, a spring, and a movable pressure ring. The fixed pressure ring and the movable pressure ring are respectively clamped at both ends of the spring, and the movable pressure ring is used to abut against the end of the nut.

4. A damped reversing electric cylinder according to claim 3, characterized in that, One end of the outer tube assembly is fixed to the connecting seat of the bearing seat assembly, and the other end of the outer tube assembly is connected to the flange. One of the dampers' retaining rings is fixed to the connecting seat, and the other damper's retaining ring is fixed to the flange.

5. A damped reversing electric cylinder according to claim 4, characterized in that, The inner ring of the flange is provided with a seal that contacts the body of the push rod.

6. A damped reversing electric cylinder according to claim 1, characterized in that, The outer tube assembly includes an outer tube and a guide rail installed inside the outer tube. The nut has a groove that cooperates with the guide rail. The nut can move along the guide rail. The guide rail is parallel to the axis of the outer tube.

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