Secure release linear actuator

Abstract

The utility model discloses a linear actuator capable of releasing safely, which solves the technical problem that the releasing speed of the existing linear actuator is too fast, and comprises a motor, a linear actuator body, a linear actuator body and a driving device, a transmission assembly; the screw rod is driven to rotate by the motor power transmitted by the transmission assembly; the tubular telescopic component is sleeved outside the lead screw and is driven by the rotary motion of the lead screw to do linear telescopic motion; the clutch is used for keeping or cutting off power transmission between the transmission assembly and the lead screw; the release part drives the clutch to cut off power transmission between the transmission assembly and the lead screw so as to activate a release function; a sealing device is installed on the lead screw, a buffering cavity is formed between the sealing device and the end, away from the transmission assembly, of the tubular telescopic component, the sealing device comprises a sealing piece and an air channel communicated with the buffering cavity, and the sealing piece adjusts the opening degree of the air channel along with linear telescopic movement of the tubular telescopic component.

Description

[Technical field]

[0001] The utility model relates to the technical field of linear actuators, in particular to a linear actuator with safe release. [Background technology]

[0002] Linear actuators, also known as electric push rods, are widely used in furniture, medical equipment, solar power generation and other fields. Their main structures include motors, transmission components, screws and tubular telescopic parts, where the transmission components include transmission worms and worm wheels, and the tubular telescopic parts include nuts threaded on the outside of the screws and inner tubes fixedly sleeved on the outside of the nut. The working principle is that the motor drives the transmission worm to rotate, the transmission worm engages with the worm wheel to drive the worm wheel to rotate, the worm wheel rotation drives the screw to rotate, the screw rotation drives the nut to move axially, and the nut drives the inner tube to move axially, thereby realizing the telescopic movement of the tubular telescopic part.

[0003] Combined with the application environment of the linear actuator, when the linear actuator encounters a motor failure, power outage or other situations where power needs to be cut off, in order to release the inner tube and retract it, a clutch and a release component are usually added, wherein the clutch is used to maintain or cut off the power transmission between the worm gear and the lead screw, and the release component is used to drive the clutch to cut off the power transmission between the worm gear and the lead screw and activate the release function, so that the reverse push can be achieved by manually driving the lead screw to rotate, thereby retracting the inner tube. Under the existing release function, the release speed of the inner tube is too fast, which will cause a large impact on the clutch, thereby shortening the service life of the clutch. At the same time, when used on an electric bed or a transfer machine, it is also easy to cause objects or people on the product to fall quickly, causing safety hazards. [Contents of the utility model]

[0004] The technical problem to be solved by the utility model is to overcome the deficiencies of the prior art and provide a safe-release linear actuator, which can slowly release the tubular telescopic component to extend the service life of the clutch and also improve the safety of product use.

[0005] In order to solve the above technical problems, the utility model adopts the following technical solutions:

[0006] Linear actuator with safety release, including:

[0007] Motor;

[0008] Transmission components;

[0009] A screw rod is driven to rotate by the motor power transmitted by the transmission assembly;

[0010] A tubular telescopic component is sleeved outside the screw rod and driven by the rotational movement of the screw rod to perform linear telescopic movement;

[0011] A clutch, used to maintain or cut off the power transmission between the transmission assembly and the screw rod;

[0012] A release component drives the clutch to cut off the power transmission between the transmission assembly and the screw rod to activate a release function;

[0013] A sealing device is installed on the screw rod, and a buffer cavity is formed between the sealing device and the end of the tubular telescopic component away from the transmission assembly. The sealing device includes a sealing member and an airway connected to the buffer cavity, and the sealing member adjusts the airway opening along with the linear telescopic movement of the tubular telescopic component.

[0014] In the above-mentioned safety release linear actuator, the tubular telescopic component has an extension stroke and a retraction stroke. When the tubular telescopic component is in the retraction stroke, it compresses the buffer chamber and drives the sealing member to move to reduce the opening of the airway.

[0015] In the above-mentioned safe release linear actuator, a cavity located outside the screw is provided between the sealing device and one end of the tubular telescopic component close to the transmission assembly. When the tubular telescopic component is in an extended stroke, the sealing element is driven to move to increase the airway opening so that the airway connects the cavity and the buffer cavity. When the tubular telescopic component is in a retracted stroke, the airway opening is reduced.

[0016] In the above-mentioned safe release linear actuator, the tubular telescopic component includes a nut installed on the outside of the screw and an inner tube fixedly sleeved on the outside of the nut, the sealing device also includes a column arranged on the screw, the seal is slidably sleeved on the column, the seal is interference fit with the inner wall of the inner tube, the outer peripheral side of the column is provided with a groove extending along the axial direction of the column or spirally extending around the axis of the screw, the airway is formed in the groove, one end of the airway is connected to the buffer chamber, and the seal adjusts the opening of the other end of the airway with the linear telescopic movement of the tubular telescopic component.

[0017] In the above-mentioned safety release linear actuator, the opening degree of the other end of the airway opened by the seal when the tubular telescopic component is extended is greater than the opening degree of the other end of the airway opened by the seal when the tubular telescopic component is retracted.

[0018] In the above-mentioned safe release linear actuator, two axially spaced limit plates are also protruded from the outer peripheral side of the cylinder, a flow gap is provided between the limit plates and the tubular telescopic component, the seal is defined between the two limit plates, and one end of the groove passes through the limit plate close to the buffer cavity.

[0019] In the above-mentioned safe release linear actuator, the sealing device further comprises a screw threadedly connected to the screw rod, and the column and the screw are integrally formed; or the column and the screw rod are integrally formed.

[0020] In the above-mentioned safe release linear actuator, the sealing device also includes a column arranged on the screw rod, and two axially spaced limit plates are protruding from the outer peripheral side of the column. A flow gap is provided between the limit plate and the tubular telescopic part, and the seal is confined between the two limit plates.

[0021] In the above-mentioned safe release linear actuator, the sealing device is arranged at the end of the screw rod away from the transmission assembly, the tubular telescopic component includes an inner tube and a pull head, the pull head is connected to the end of the inner tube away from the transmission assembly, and the part inside the inner tube between the sealing device and the pull head forms the buffer chamber.

[0022] In the above-mentioned safe release linear actuator, the clutch is arranged between the transmission assembly and the screw, the clutch rotates synchronously with the screw and is arranged to slide axially along the screw, and the release component drives the clutch to move axially along the screw to disengage the clutch from the transmission assembly and activate the release function.

[0023] Beneficial effects of the utility model:

[0024] 1. A sealing device is installed on the screw rod in the utility model, and a buffer chamber is formed between the sealing device and the end of the tubular telescopic component away from the transmission assembly. The sealing device includes a sealing member and an airway connected to the buffer chamber, and the sealing member adjusts the airway opening along with the linear telescopic movement of the tubular telescopic component. Since the buffer chamber is arranged between the sealing device and the end of the tubular telescopic component away from the transmission assembly, and in the process of retracting the tubular telescopic component, the distance between the end of the tubular telescopic component away from the transmission assembly and the sealing device becomes closer and closer, the volume of the buffer chamber will gradually decrease. By setting the sealing member to reduce the airway opening along with the retraction of the tubular telescopic component, the gas in the buffer chamber can be slowly released to the outside or not released to the outside. In this way, the pressure in the buffer chamber can gradually increase along with the increase of the retraction stroke of the tubular telescopic component. Under the action of the air pressure in the buffer chamber, the retraction speed of the tubular telescopic component will become slower and slower until the airway is retracted. until it is fully retracted, thereby achieving the purpose of slow release, thereby improving the safety of product use, and allowing objects or personnel connected to the tubular telescopic component to descend smoothly; in addition, when the release function is activated, the clutch will contact the housing along the axial direction of the screw rod. Since the tubular telescopic component retracts slowly, the impact force on the housing along the axial direction of the screw rod when it is fully retracted is relatively small, that is, the axial impact force transmitted to the clutch through the housing is also reduced, thereby extending the service life of the clutch; finally, only one sealing device needs to be set in the utility model, the structure is simple, and it is convenient for mass production.

[0025] 2. The tubular telescopic component has an extension stroke and a retraction stroke. When the tubular telescopic component is in the retraction stroke, it compresses the buffer cavity and drives the seal to move to reduce the opening of the airway. This design enables the tubular telescopic component to not only compress the buffer cavity during the retraction stroke, but also reduce the opening of the airway by driving the seal to move, so that the gas in the buffer cavity is slowly released or not released through the airway to quickly increase the pressure in the buffer cavity. Under the action of the pressure in the buffer cavity, the retraction speed of the tubular telescopic component will become slower and slower, achieving the purpose of slow release.

[0026] 3. A cavity located outside the screw rod is provided between the sealing device and the end of the tubular telescopic component close to the transmission assembly. When the tubular telescopic component is in the extension stroke, the seal is driven to move to increase the airway opening so that the airway connects the cavity and the buffer cavity. When the tubular telescopic component is in the retraction stroke, the airway opening decreases. With such a design, when the tubular telescopic component is in the extension stroke, the volume of the cavity will gradually decrease as the end of the tubular telescopic component close to the transmission assembly gradually approaches the sealing device. In order to avoid the increase of pressure in the cavity and hinder the extension of the tubular telescopic component, the seal is driven to move to increase the airway opening so that the airway connects the cavity and the buffer cavity. The gas in the cavity can enter the buffer cavity through the airway to reduce the pressure in the cavity, so that the tubular telescopic component can be extended smoothly.

[0027] 4. The tubular telescopic component includes a nut installed on the outside of the screw and an inner tube fixedly sleeved on the outside of the nut. The sealing device also includes a column arranged on the screw. The sealing member is slidably sleeved on the column. The sealing member is interference-fitted with the inner wall of the inner tube. The outer peripheral side of the column is provided with a groove extending along the axial direction of the column or spirally extending around the axis of the screw. An airway is formed in the groove. One end of the airway is connected to the buffer chamber. The sealing member adjusts the opening of the other end of the airway with the linear telescopic movement of the tubular telescopic component. With such a design, the friction between the inner tube and the sealing member can be used to drive the sealing member to move along the axial direction of the column when the tubular telescopic component is extended and retracted, so as to adjust the opening of the other end of the airway. No other components are required, so the structure is simpler.

[0028] 5. The opening of the other end of the airway opened by the seal when the tubular telescopic component is extended is greater than the opening of the other end of the airway opened by the seal when the tubular telescopic component is retracted. With this design, when the tubular telescopic component is extended, a large amount of gas enters the buffer cavity through the airway, so that there is more gas in the buffer cavity, and when it is released, the pressure in the buffer cavity rises quickly, realizing slow release.

[0029] 6. Two axially spaced limiting plates are also provided on the outer peripheral side of the column. A flow gap is provided between the limiting plates and the tubular telescopic component. The seal is limited between the two limiting plates, and one end of the groove passes through the limiting plate near the buffer cavity. With this design, the axial movement distance of the seal on the column can be limited by the two limiting plates to prevent the seal from detaching from the column and failing to form a buffer cavity; in addition, during the extension of the tubular telescopic component, even if the seal is against the limiting plate near the buffer cavity, the gas can enter the buffer cavity through the airway.

[0030] 7. The sealing device also includes a screw threadedly connected to the screw rod, and the column and the screw are integrally processed and formed; such a design can reduce the difficulty of processing the screw rod; or, the column and the screw rod are integrally processed and formed, such a design can reduce the number of parts and components to reduce the number of assembly steps.

[0031] 8. The sealing device also includes a column arranged on the screw rod, and two axially spaced limiting plates are convexly arranged on the outer peripheral side of the column. A flow gap is provided between the limiting plates and the tubular telescopic component, and the sealing member is limited between the two limiting plates. With such a design, the axial movement distance of the sealing member on the column can be limited by the two limiting plates to prevent the sealing member from being separated from the column and unable to form a buffer cavity; in addition, during the extension of the tubular telescopic component, even if the sealing member abuts against the limiting plate close to the buffer cavity, the gas can enter the buffer cavity through the airway.

[0032] 9. The sealing device is arranged at the end of the screw rod away from the transmission assembly, and the tubular telescopic component includes an inner tube and a pull head, the pull head is connected to the end of the inner tube away from the transmission assembly, and the portion of the inner tube between the sealing device and the pull head forms the buffer chamber. Such a design can effectively increase the setting length of the external thread on the screw rod, thereby increasing the extension stroke of the tubular telescopic component.

Brief Description of the Drawings

[0033] The utility model is further described below in conjunction with the accompanying drawings:

[0034] Figure 1 This is a schematic diagram of the structure of the linear actuator in the first embodiment of the utility model;

[0035] Figure 2 This is an exploded schematic diagram of the linear actuator in the first embodiment of the utility model after the housing is removed;

[0036] Figure 3 The structure of the screw in the first embodiment of the utility model is shown in FIG. Figure 1 ;

[0037] Figure 4 The structure of the screw in the first embodiment of the utility model is shown in FIG. Figure 2 ;

[0038] Figure 5It is a cross-sectional view of the screw in the first embodiment of the utility model;

[0039] Figure 6 This is a schematic diagram of the structure of the linear actuator in Embodiment 1 of the utility model after the housing is removed;

[0040] Figure 7 for Figure 6 A cross-sectional view of

[0041] Figure 8 for Figure 7 A is a partial enlarged schematic diagram;

[0042] Fig. 9 This is a schematic diagram of the sealing member in the first embodiment of the present utility model abutting against the limiting plate close to the buffer cavity;

[0043] Fig.10 Schematic diagram of the sealing member in the first embodiment of the utility model abutting against the limit plate near the buffer cavity

[0044] Fig.11 This is a schematic diagram of the structure of the screw in the second embodiment of the utility model;

[0045] Reference numerals:

[0046] 001, buffer chamber; 002, cavity; 100, motor; 200, transmission assembly; 210, transmission worm; 220, worm wheel; 300, lead screw; 310, spline; 400, tubular telescopic component; 410, nut; 420, inner tube; 430, pull head; 500, clutch; 510, annular groove; 600, release component; 610, release rod; 620, lever; 621, insert rod; 630, cable; 640, elastic return member; 700, housing; 800, sealing device; 801, airway; 810, sealing member; 820, column; 821, limit plate; 8211, through hole; 830, screw; 900, elastic return member. [Specific implementation method]

[0047] The utility model provides a linear actuator with safe release, comprising:

[0048] Motor;

[0049] Transmission components;

[0050] A screw rod is driven to rotate by the motor power transmitted by the transmission assembly;

[0051] A tubular telescopic component is sleeved outside the screw rod and driven by the rotational movement of the screw rod to perform linear telescopic movement;

[0052] A clutch, used to maintain or cut off the power transmission between the transmission assembly and the screw rod;

[0053] A release component drives the clutch to cut off the power transmission between the transmission assembly and the screw rod to activate a release function;

[0054] A sealing device is installed on the screw rod, and a buffer cavity is formed between the sealing device and the end of the tubular telescopic component away from the transmission assembly. The sealing device includes a sealing member and an airway connected to the buffer cavity, and the sealing member adjusts the airway opening along with the linear telescopic movement of the tubular telescopic component.

[0055] A sealing device is installed on the screw rod in the utility model, and a buffer chamber is formed between the sealing device and the end of the tubular telescopic component away from the transmission assembly. The sealing device includes a sealing member and an airway connected to the buffer chamber, and the sealing member adjusts the airway opening along with the linear telescopic movement of the tubular telescopic component. Since the buffer chamber is arranged between the sealing device and the end of the tubular telescopic component away from the transmission assembly, and in the process of retracting the tubular telescopic component, the distance between the end of the tubular telescopic component away from the transmission assembly and the sealing device becomes closer and closer, the volume of the buffer chamber will gradually decrease. By setting the sealing member to reduce the airway opening along with the retraction of the tubular telescopic component, the gas in the buffer chamber can be slowly released to the outside or not released to the outside. In this way, the pressure in the buffer chamber can be gradually increased along with the increase of the retraction stroke of the tubular telescopic component. Under the action of the air pressure in the buffer chamber, the retraction speed of the tubular telescopic component will become slower and slower until the airway is retracted. until it is fully retracted, thereby achieving the purpose of slow release, thereby improving the safety of product use, and allowing objects or personnel connected to the tubular telescopic component to descend smoothly; in addition, when the release function is activated, the clutch will contact the housing along the axial direction of the screw rod. Since the tubular telescopic component retracts slowly, the impact force on the housing along the axial direction of the screw rod when it is fully retracted is relatively small, that is, the axial impact force transmitted to the clutch through the housing is also reduced, thereby extending the service life of the clutch; finally, only one sealing device needs to be set in the utility model, the structure is simple, and it is convenient for mass production.

[0056] The technical scheme of the embodiment of the utility model is explained and illustrated below in conjunction with the drawings of the embodiment of the utility model, but the following embodiments are only preferred embodiments of the utility model, not all. Based on the embodiments in the implementation mode, other embodiments obtained by those skilled in the art without making creative work all belong to the protection scope of the utility model. In addition, it should be understood that the following words indicating orientation or position relationship such as "up", "down", "left", "right", "longitudinal", "lateral", "inside", "outside", "vertical", "horizontal", "top", "bottom", etc. are only based on the orientation or position relationship shown in the drawings, only for the convenience of describing the utility model and simplifying the description, rather than indicating or implying that the device / element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the utility model.

[0057] Embodiment 1

[0058] like Figures 1 to 10 As shown, the linear actuator with safe release in this embodiment includes a motor 100, a transmission assembly 200, a screw 300, a tubular telescopic component 400, a clutch 500, a release component 600 and a housing 700, wherein the transmission assembly 200 includes a transmission worm 210 and a worm wheel 220 meshing with the transmission worm 210, the transmission worm 210 is connected to the motor 100, and the worm wheel 220 is rotatably connected to the screw 300, that is, the worm wheel 220 is sleeved on the screw 300 and can rotate relative to the screw 300, that is, it does not rotate with the screw 300, and the tubular telescopic component 400 is threadedly connected to the screw 300. 00 and is driven by the rotation of the screw rod 300 to perform linear telescopic movement. The clutch 500 is arranged between the worm wheel 220 and the screw rod 300. The clutch 500 is used to maintain or cut off the power transmission between the transmission assembly 200 and the screw rod 300. When the clutch 500 maintains the power transmission between the worm wheel 220 and the screw rod 300, the motor 100 can drive the screw rod 300 to rotate through the transmission assembly 200 to make the tubular telescopic component 400 perform telescopic movement. The release component 600 is used to drive the clutch 500 to cut off the power transmission between the transmission assembly 200 and the screw rod 300 and activate the release function. The output end of the motor 100, the transmission assembly 200, the screw rod 300, and the clutch 500 are all arranged in the housing 700.

[0059] A sealing device 800 is installed on the screw rod 300 in this embodiment, and a buffer chamber 001 is formed between the sealing device 800 and the end of the tubular telescopic component 400 away from the transmission assembly 200. The sealing device 800 includes a sealing member 810 and an air passage 801 connected to the buffer chamber 001. The sealing member 810 adjusts the opening of the air passage 801 along with the linear telescopic movement of the tubular telescopic component 400.

[0060] When the linear actuator is in use, since the buffer chamber 001 is arranged between the sealing device 800 and the end of the tubular telescopic component 400 away from the transmission assembly 200, and during the retraction process of the tubular telescopic component 400, the distance between the end of the tubular telescopic component 400 away from the transmission assembly 200 and the sealing device 800 becomes closer and closer, the volume of the buffer chamber 001 will gradually decrease. By setting the sealing member 810 to reduce the opening of the airway 801 as the tubular telescopic component 400 retracts, the gas in the buffer chamber 001 can be slowly released or not released to the outside. In this way, the pressure in the buffer chamber 001 can gradually increase as the retraction stroke of the tubular telescopic component 400 increases. Under the action of the air pressure in the buffer chamber 001, the tubular telescopic component 400 0 will retract more and more slowly until it is fully retracted, thereby achieving the purpose of slow release, thereby improving the safety of product use, and allowing objects or personnel connected to the tubular telescopic component 400 to descend smoothly; in addition, when the release function is activated, the clutch 500 will contact the housing 700 along the axial direction of the screw rod 300. Since the tubular telescopic component 400 retracts slowly, the impact force on the housing 700 along the axial direction of the screw rod 300 when it is fully retracted is relatively small, that is, the axial impact force transmitted to the clutch 500 through the housing 700 is also reduced, thereby extending the service life of the clutch 500; finally, only one sealing device 800 is required in the utility model, which has a simple structure and is convenient for mass production.

[0061] Specifically, the tubular telescopic component 400 in this embodiment has an extension stroke and a retraction stroke. When the tubular telescopic component 400 is in the retraction stroke, it compresses the buffer chamber 001 and drives the seal 810 to move to reduce the opening of the airway 801. With such a design, the tubular telescopic component 400 can not only compress the buffer chamber 001 in the retraction stroke, but also reduce the opening of the airway 801 by driving the seal 810 to move, so that the gas in the buffer chamber 001 is slowly released or not released through the airway 801, so as to quickly increase the pressure in the buffer chamber 001. Under the action of the pressure in the buffer chamber 001, the retraction speed of the tubular telescopic component 400 will become slower and slower, so as to achieve the purpose of slow release.

[0062] Preferably, a cavity 002 located outside the screw rod 300 is provided between the sealing device 800 and the end of the tubular telescopic component 400 close to the transmission assembly 200. For the convenience of the following description, in this embodiment, the end of the tubular telescopic component 400 close to the transmission assembly 200 is defined as the rear end, and the end of the tubular telescopic component 400 away from the transmission assembly 200 is defined as the front end. When the tubular telescopic component 400 is in the extension stroke, the front end of the tubular telescopic component 400 extends toward the outside of the shell 700 and gradually moves away from the shell 700, and the movement of the tubular telescopic component 400 can drive the seal 810 to move to increase the opening of the airway 801, so that the airway 801 connects the cavity 002 and the buffer cavity 001. When the tubular telescopic component 400 is in the retraction stroke, the front end of the tubular telescopic component 400 retracts toward the inside of the shell 700 and gradually approaches the shell 700, and the movement of the tubular telescopic component 400 can drive the seal 810 to move to reduce the opening of the airway 801. With such a design, when the tubular telescopic component 400 is in the extension stroke, the volume of the cavity 002 will gradually decrease as the rear end of the tubular telescopic component 400 gradually approaches the sealing device 800. In order to prevent the pressure in the cavity 002 from increasing and hindering the extension of the tubular telescopic component 400, the seal 810 is driven to move to increase the opening of the airway 801, so that the airway 801 connects the cavity 002 and the buffer cavity 001. The gas in the cavity 002 can quickly enter the buffer cavity 001 through the airway 801 to reduce the pressure in the cavity 002, so that the tubular telescopic component 400 can be smoothly extended.

[0063] The tubular telescopic component 400 in this embodiment includes a nut 410, an inner tube 420 and a pull head 430. The nut 410 is sleeved on the outside of the screw rod 300 and is threadedly connected to the screw rod 300. One end of the inner tube 420 close to the transmission assembly 200 is fixedly sleeved on the outside of the nut 410. The pull head 430 is threadedly connected to the other end of the inner tube 420 and closes the end. The sealing device 800 is installed on the screw rod 300 and is located in the inner tube 420, wherein the cavity 002 is the part inside the inner tube 420 located between the nut 410 and the seal 810, and the buffer cavity 001 is the part inside the inner tube 420 located between the seal 810 and the pull head 430.

[0064] The sealing device 800 in this embodiment also includes a column 820 fixed on the screw rod 300, and a sealing member 810 is slidably sleeved on the column 820. The sealing member 810 is interference fit with the inner wall of the inner tube 420 so that the outer peripheral side of the sealing member 810 maintains contact and sealing with the inner wall of the inner tube 420. A plurality of grooves are circumferentially spaced on the outer peripheral side of the column 820, and each groove extends along the axial direction of the column 820. The above-mentioned airway 801 is formed inside the groove. One end of the airway 801 is always connected to the buffer cavity 001, and the sealing member 810 adjusts the opening of the other end of the airway 801 with the linear telescopic movement of the tubular telescopic component 400. It should be noted that the opening of the other end of the airway 801 refers to the opening size of the notch of the groove on the side of the seal 810 away from the buffer cavity 001. The larger the opening of the notch of the groove on the side of the seal 810 away from the buffer cavity 001, the larger the opening of the other end of the airway 801. With such a design, the friction between the inner tube 420 and the seal 810 can be used to drive the seal 810 to move axially along the column 820 when the tubular telescopic component 400 is extended or retracted, so as to adjust the opening of the other end of the airway 801. No other components are required, so the structure is simpler.

[0065] In addition, in order to prevent the seal 810 from detaching from the column 820 and being unable to adjust the opening of the other end of the airway 801, two axially spaced limit plates 821 are also protruded from the outer peripheral side of the column 820 in this embodiment, and the outer diameter of the limit plate 821 is smaller than the inner diameter of the inner tube 420, so that a flow gap is provided between the limit plate 821 and the tubular telescopic component 400, and the seal 810 is confined between the two limit plates 821, one end of the groove passes through the limit plate 821 close to the buffer cavity 001 and is always connected to the buffer cavity 001, and the other end extends to the inner side surface of the other limit plate 821. With such a design, the axial movement distance of the seal 810 on the column 820 can be limited by the two limit plates 821, so as to prevent the seal 810 from being separated from the column 820 and failing to form the buffer cavity 001; in addition, during the extension of the tubular telescopic component 400, even if the seal 810 is against the limit plate 821 close to the buffer cavity 001, the gas can enter the buffer cavity 001 through the airway 801, so that one end of the airway 801 is always connected with the buffer cavity 001.

[0066] When the tubular telescopic member 400 is normally extended, the volume of the cavity 002 becomes larger and larger. Since the sealing member 810 and the inner tube 420 are in interference fit, the sealing member 810 moves toward the side of the limit plate 821 close to the buffer cavity 001 under the drive of the inner tube 420 until it abuts against the inner side surface of the limit plate 821 (such as Fig. 9As shown), under the action of negative air pressure, the gas enters the buffer chamber 001 from the cavity 002 through the air passage 801, thereby ensuring that the air pressure in the cavity 002 and the buffer chamber 001 is always balanced, and also ensuring that the tubular telescopic component 400 extends smoothly; when the release component 600 drives the clutch 500 to cut off the power transmission between the transmission assembly 200 and the screw rod 300 and activates the release function, the tubular telescopic component 400 retracts under the action of the load pressure, and driven by the inner tube 420, the sealing member 810 moves toward the side of the limit plate 821 close to the cavity 002 to reduce the opening of the other end of the air passage 801 until it abuts against the inner side surface of the limit plate 821 (as shown in FIG. Fig.10 As shown), at this time, the other end of the airway 801 is completely blocked by the seal 810, and the opening of the airway 801 is 0. At this time, the buffer chamber 001 is in a completely sealed state, and the air pressure in the buffer chamber 001 is getting higher and higher. Under the action of the air pressure, the retraction speed of the tubular telescopic component 400 is getting slower and slower until it is completely retracted.

[0067] Preferably, the opening of the other end of the air passage 801 opened by the seal 810 when the tubular telescopic component 400 is extended is greater than the opening of the other end of the air passage 801 opened by the seal 810 when the tubular telescopic component 400 is retracted. With such a design, when the tubular telescopic component 400 is extended, a large amount of gas enters the buffer cavity 001 through the air passage 801, so that there is more gas in the buffer cavity 001, and when it is released, the pressure in the buffer cavity 001 rises rapidly, and a slow release is achieved. At the same time, the pressure in the cavity 002 can be quickly reduced to ensure that the tubular telescopic component 400 is smoothly extended. Finally, the air passage 801 can be hidden in the inner tube 420 to prevent external dust from entering the inner tube 420.

[0068] The sealing device 800 in this embodiment also includes a screw 830 threadedly connected to the screw rod 300. The screw 830 includes a screw rod and a screw head. The column 820 is the screw head of the screw 830, that is, the column 820 and the screw 830 are integrally processed and formed. Such a design can reduce the processing difficulty of the screw rod 300. The screw 830 and the column 820 in this embodiment are metal parts. In order to facilitate the processing and forming of the groove outside the column 820, a plurality of through holes 8211 are circumferentially spaced around the axis of the column 820 on the limiting plate 821 close to the buffer cavity 001 in this embodiment. The minimum distance between the hole wall of the through hole 8211 and the axis of the column 820 is less than the outer diameter of the column 820. In this way, when punching the through hole 8211 on the limiting plate 821 to form the through hole 8211, the groove can be formed by extending the punching distance, thereby reducing the processing difficulty of the groove.

[0069] In order to maximize the extension stroke of the tubular telescopic component 400 when the length of the screw rod 300 is constant, the sealing device 800 in this embodiment is arranged at the end of the screw rod 300 away from the transmission assembly 200, and a threaded hole is provided at the end of the screw rod 300 away from the transmission assembly 200, and the screw 830 is locked in the threaded hole. In this way, the part of the inner tube 420 located between the sealing device 800 and the pull head 430 forms the buffer cavity 001, thereby effectively increasing the setting length of the external thread on the screw rod 300, thereby increasing the extension stroke of the tubular telescopic component 400.

[0070] Finally, in order to realize that the release component 600 drives the clutch 500 to cut off the power transmission between the transmission assembly 200 and the screw rod 300 and activate the release function, in this embodiment, the end of the screw rod 300 close to the worm gear 220 is provided with a synchronously rotating spline 310, one end of the screw rod 300 is a non-circular cross-section, and the spline 310 is provided with a non-circular hole for one end of the screw rod 300 to pass through, so as to realize the synchronous rotation of the screw rod 300 and the spline 310, and the clutch 500 includes a keyway that cooperates with the spline 310, so as to ensure that the clutch 500 does not move relative to the screw rod 300 in the circumferential direction, but can move axially along the spline 310 in the axial direction, that is, the clutch 500 and the screw rod 300 rotate synchronously and are set to slide axially along the screw rod 300. The end surface of the clutch 500 facing the worm wheel 220 is provided with a transmission protrusion, and the worm wheel 220 is provided with a transmission groove. Through the insertion of the transmission protrusion and the transmission groove, the power of the worm wheel 220 can be transmitted to the clutch 500, and then transmitted to the spline 310 and the screw rod 300 through the clutch 500. Of course, the transmission protrusion can also be provided on the worm wheel, and the transmission groove can be provided on the clutch.

[0071] The release component 600 includes a release rod 610, a lever 620 and a cable 630. An annular groove 510 is provided on the outer peripheral side of the clutch 500. The lever 620 is provided with an insertion rod 621 inserted into the annular groove 510. The number of the insertion rods 621 can be one, two or three. The insertion of the insertion rod 621 into the annular groove 510 will not affect the rotation of the clutch 500, but can only push the clutch 500 to move along the axial direction of the screw rod 300. The cable 630 pulls the release rod 610 so that the release rod 610 drives the lever 620 to slide along the axial direction parallel to the screw rod 300, so that the clutch 500 is away from the worm gear 220, even if the transmission protrusion is disengaged from the transmission groove, thereby cutting off the power transmission between the transmission assembly 200 and the screw rod 300, that is, releasing the lock on the screw rod 300. In addition, the release rod 610 is also connected to an elastic reset member 900, which can push the clutch 500 to reset after the cable 630 removes the external force, so that the transmission protrusion is plugged into the transmission groove to ensure that the linear actuator can operate normally.

[0072] It can be understood that in other embodiments of the present invention, the groove may also extend spirally around the axis of the screw rod, with one end of the groove penetrating through a limit plate disposed near the buffer cavity and the other end being located between the two limit plates.

[0073] It is understandable that in other embodiments of the present invention, when the axial length of the column is long enough, the two limit plates may not be provided.

[0074] It can be understood that in other embodiments of the present invention, when the axial length of the groove is long enough, when the tubular telescopic component is in the process of retracting, the seal finally stops at the position between the other end of the groove and the limit plate close to the buffer cavity (such as Figure 8 As shown), that is, although the airway opening is reduced, the gas in the buffer cavity can still be slowly released into the cavity through the airway. Such a design can also achieve the purpose of slowly releasing the tubular telescopic component.

[0075] It can be understood that in other embodiments of the present invention, the airway includes a radial channel and an axial channel. The radial channel extends radially inward from the outer peripheral side of the cylinder to the axis of the cylinder, while the axial channel extends inward from the end surface of the cylinder close to the buffer cavity and is connected with the radial channel. The radial channel is located at one end of the outer peripheral side of the cylinder to form a first opening. When the tubular telescopic component is in the process of retraction, the seal completely blocks the first opening or partially blocks the first opening or is located on the side of the first opening away from the buffer cavity to reduce the opening of the first opening, that is, to reduce the opening of the airway, so as to increase the pressure in the buffer cavity and achieve the purpose of slow release; and when the tubular telescopic component is in the process of extension, the seal is located on the side of the first opening close to the buffer cavity to keep the first opening connected with the cavity.

[0076] It can be understood that in other embodiments of the present invention, the column and the screw rod are integrally formed. Such a design can reduce the number of parts and components, thereby reducing the number of assembly steps.

[0077] Embodiment 2

[0078] like Fig.11 As shown, compared with the first embodiment, the difference of this embodiment is that the other end of the groove is spaced apart from the limit plate 821 arranged near the cavity 002, and when the tubular telescopic component 400 is in the process of retraction, the seal 810 is finally located between the limit plate 821 arranged near the cavity 002 and the other end of the groove to achieve complete blocking of the other end of the airway 801, and the opening of the airway 801 is 0, and the buffer cavity 001 is in a completely sealed state.

[0079] The above is only a specific implementation of the utility model, but the protection scope of the utility model is not limited thereto. Those skilled in the art should understand that the utility model includes but is not limited to the contents described in the drawings and the above specific implementation. Any modification that does not deviate from the functional and structural principles of the utility model will be included in the scope of the claims.

Claims

1. A linear actuator with safety release, comprising: Motor; Transmission components; A screw rod is driven to rotate by the motor power transmitted by the transmission assembly; A tubular telescopic component is sleeved outside the screw rod and driven by the rotational movement of the screw rod to perform linear telescopic movement; A clutch, used to maintain or cut off the power transmission between the transmission assembly and the screw rod; A release component drives the clutch to cut off the power transmission between the transmission assembly and the screw rod to activate a release function; It is characterized in that a sealing device is installed on the screw rod, and a buffer cavity is formed between the sealing device and the end of the tubular telescopic component away from the transmission assembly. The sealing device includes a sealing member and an airway connected to the buffer cavity, and the sealing member adjusts the airway opening with the linear telescopic movement of the tubular telescopic component.

2. The safety release linear actuator of claim 1, wherein: The tubular telescopic component has an extension stroke and a retraction stroke. When the tubular telescopic component is in the retraction stroke, it compresses the buffer cavity and drives the sealing element to move to reduce the opening of the airway.

3. The safety release linear actuator of claim 2, wherein: A cavity located outside the screw rod is provided between the sealing device and one end of the tubular telescopic component close to the transmission assembly. When the tubular telescopic component is in an extended stroke, the sealing component is driven to move to increase the airway opening so that the airway connects the cavity and the buffer cavity. When the tubular telescopic component is in a retracted stroke, the airway opening is reduced.

4. A linear actuator with safety release according to any one of claims 1 to 3, characterized in that: The tubular telescopic component includes a nut installed on the outside of the screw and an inner tube fixedly sleeved on the outside of the nut. The sealing device also includes a column arranged on the screw. The seal is slidably sleeved on the column. The seal has an interference fit with the inner wall of the inner tube. The outer peripheral side of the column is provided with a groove extending along the axial direction of the column or spirally extending around the axis of the screw. The airway is formed in the groove. One end of the airway is connected to the buffer chamber. The seal adjusts the opening of the other end of the airway with the linear telescopic movement of the tubular telescopic component.

5. The safety release linear actuator of claim 4, wherein: The opening degree of the other end of the airway opened when the sealing member extends along with the tubular telescopic member is greater than the opening degree of the other end of the airway opened when the sealing member retracts along with the tubular telescopic member.

6. The safety release linear actuator of claim 4, wherein: The outer peripheral side of the column is also convexly provided with two axially spaced limit plates, the limit plates and the tubular telescopic component are provided with a flow gap, the sealing member is defined between the two limit plates, and one end of the groove passes through the limit plate close to the buffer cavity.

7. The safety release linear actuator of claim 4, wherein: The sealing device further comprises a screw threadedly connected to the screw rod, and the column and the screw are integrally formed; or the column and the screw rod are integrally formed.

8. A linear actuator with safety release as claimed in any one of claims 1 to 3, characterized in that: The sealing device also includes a column arranged on the screw rod, and two axially spaced limiting plates are protruded from the outer peripheral side of the column. A flow gap is provided between the limiting plates and the tubular telescopic component, and the sealing member is limited between the two limiting plates.

9. A linear actuator with safety release as claimed in any one of claims 1 to 3, characterized in that: The sealing device is arranged at one end of the screw rod away from the transmission assembly. The tubular telescopic component includes an inner tube and a pull head. The pull head is connected to the end of the inner tube away from the transmission assembly. The part inside the inner tube between the sealing device and the pull head forms the buffer chamber.

10. A linear actuator with safety release according to any one of claims 1 to 3, characterized in that: The clutch is arranged between the transmission assembly and the screw rod. The clutch rotates synchronously with the screw rod and is arranged to slide along the axial direction of the screw rod. The release component drives the clutch to move along the axial direction of the screw rod to disengage the clutch from the transmission assembly and activate the release function.

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