Linear actuator and shifter
By adopting the structure of the transmission wheel and screw in the linear actuator, combined with elastic components and self-locking device, the problems of obstacle extrusion and connection damage during retraction of the linear actuator are solved, and safe object movement and Operation for user control.
Patent Information
- Application Number
- CN202421022090.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-11
- Publication Date
- 2024-12-10
- Estimated Expiration
- 2034-05-11
AI Technical Summary
When existing linear actuators encounter obstacles during retraction, they can easily cause damage to the connection and cannot continue to move. The object will fall off quickly after the obstacle is removed, which may cause damage.
A linear actuator is designed, adopting a structure of a transmission wheel and a screw, wherein the screw is arranged in the transmission hole of the transmission wheel, equipped with elastic components and self-locking devices, and the transmission section and the transmission hole are moved relative to each other in the axial direction. , cut off power transmission, avoid the squeezing of obstacles during retraction, and resume engagement after the obstacle is removed, achieving safe continued operation.
It effectively avoids damage to obstacles and damage to linear actuators, ensures safe movement of objects, reduces the distance when objects fall after they are removed, and improves the safety of use and convenience of operation.
Smart Images
Figure CN222141900U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the field of linear driving, and in particular relates to a linear actuator and a shifter. Background Art
[0002] At present, linear actuators are widely used in various fields, including medical equipment, home office, solar power generation, etc. The structure of a linear actuator usually includes a drive motor, a lead screw, a lead screw nut and a tubular structure. The drive motor drives the lead screw to rotate, and when the lead screw rotates, it drives the lead screw nut to move along the axial direction of the lead screw. The lead screw nut drives the tubular structure connected to it to move along the axial direction of the lead screw, and then drives the object connected to the tubular structure to move linearly to achieve the purpose of driving.
[0003] At present, the linear actuators on the market have the following defects: when the tubular structure retracts, if the object encounters an obstacle, the object cannot continue to move, and the obstacle will apply a force opposite to the retraction direction to the object, causing the object to pull the tubular structure to disengage the tubular structure from the lead screw nut, causing the connection between the lead screw nut and the tubular structure to be damaged and the two cannot move together. The user can neither control the lead screw to reverse and drive the tubular structure to extend so that the object connected to the tubular structure is separated from the obstacle, nor can the linear actuator be directly controlled to continue to descend after removing the obstacle. When the linear actuator is used as a lifting structure, if the user directly removes the obstacle, the object installed on the tubular structure will drive the tubular structure to quickly impact a long distance downward under the action of gravity. When the object is a structure such as a hospital bed or a desktop platform, the patient on the bed or the items placed on the desktop platform are easily damaged. Utility Model Content
[0004] The technical problem to be solved by the utility model is to provide a linear actuator to solve the problem of damage caused by obstacles when the linear actuator drives an object to retract.
[0005] In order to solve the above technical problems, the utility model adopts the following technical solutions:
[0006] The linear actuator comprises: a motor; a transmission wheel driven to rotate by the motor; a screw rod driven to rotate by the transmission wheel; a tubular telescopic component driven by the rotational movement of the screw rod to perform linear telescopic movement; wherein the transmission wheel comprises a transmission hole, the screw rod comprises a transmission section, the transmission section is meshed in the transmission hole and the two are kept to rotate synchronously in the circumferential direction and can move axially relative to each other, so as to allow the screw rod to move in the extending direction of the tubular telescopic component when subjected to an axial tensile load, so as to axially separate the transmission section and the transmission hole, and cut off the power transmission between the transmission wheel and the screw rod; an elastic component acts on the screw rod to keep it in a force state in the retracting direction of the tubular telescopic component.
[0007] In the above-mentioned linear actuator, the screw rod includes a supporting section, a threaded section and a transmission section connecting the two. The transmission wheel is provided with an axially penetrating through hole, in which a transmission hole and a support hole adapted to the supporting section are formed. The support section penetrates the supporting hole and can shuttle and rotate freely in the through hole.
[0008] In the above linear actuator, an avoidance hole is also formed in the through hole, a first step surface is formed between the avoidance hole and the support hole, and the elastic component is at least partially accommodated in the avoidance hole and pre-tightened between the tail end of the screw rod and the first step surface.
[0009] In the above linear actuator, the elastic component is one of a disc spring, a coil spring, a rubber spring or a combination thereof, the elastic component is sleeved on the support section, and a stopper abutting against the elastic component is provided at the tail of the screw rod.
[0010] In the above linear actuator, a limiting hole is also formed in the through hole, and when the transmission section is in meshing state with the transmission hole, the end of the threaded section is radially limited by the limiting hole.
[0011] In the above linear actuator, a second step surface is formed between the limiting hole and the transmission hole, and a shoulder surface is formed at one end of the transmission section. When the transmission section and the transmission hole are axially separated, the shoulder surface abuts against the second step surface.
[0012] In the above-mentioned linear actuator, the linear actuator also includes a self-locking device, which includes a first friction sleeve connected to the transmission wheel, a second friction sleeve, a self-locking torsion spring and a braking element. The braking element applies a braking torque to the second friction sleeve to limit the rotation of the second friction sleeve. The self-locking torsion spring is tightly attached to the first friction sleeve and the second friction sleeve to form a self-locking state. The active rotation of the transmission wheel forces the self-locking torsion spring to release the first friction sleeve.
[0013] In the above linear actuator, the first friction sleeve is configured as a part of the transmission wheel.
[0014] In the above linear actuator, the transmission wheel includes a worm wheel and a transmission sleeve embedded in the worm wheel, the transmission hole is arranged on the transmission sleeve, and one end of the transmission sleeve axially extends out of the worm wheel to form a first friction sleeve.
[0015] In the above linear actuator, a thrust bearing is arranged between the first friction sleeve and the second friction sleeve, and the elastic component is installed at the tail of the screw rod and is accommodated in the avoidance space formed by the transmission sleeve and the thrust bearing.
[0016] In the above linear actuator, the transmission section and the transmission hole form a non-circular shaft hole fit or a keyway fit.
[0017] In the above linear actuator, the axial engagement length between the transmission section and the transmission hole is ≤15 mm.
[0018] In the above linear actuator, the tubular telescopic component includes a transmission nut and a tubular component, the transmission nut is threadably matched with the lead screw, and the tubular component and the transmission nut are inseparably connected.
[0019] The beneficial effects of the utility model are:
[0020] The linear actuator includes: a motor; a transmission wheel, which is driven to rotate by the motor; a screw rod, which is driven to rotate by the transmission wheel; a tubular telescopic component, which is driven by the rotation of the screw rod to perform linear telescopic movement; wherein the transmission wheel includes a transmission hole, and the screw rod includes a transmission section, which is engaged in the transmission hole and keeps the two rotating synchronously in the circumferential direction and can move axially relative to each other, so as to allow the screw rod to move in the extension direction of the tubular telescopic component when subjected to an axial tensile load, so as to axially separate the transmission section and the transmission hole, and cut off the power transmission between the transmission wheel and the screw rod; an elastic component, which acts on the screw rod to keep it in a state of being stressed in the retraction direction of the tubular telescopic component. The technical solution has the following technical effects:
[0021] The utility model provides a screw rod through the transmission hole of the transmission wheel, and sets the screw rod to a structure that can move along the axial direction of the transmission wheel, so that the screw rod can maintain a meshing state with the transmission hole under the push of the elastic component. At this time, the output shaft of the motor drives the transmission wheel to rotate, and the transmission wheel drives the screw rod to rotate synchronously through the meshing transmission hole and the transmission section. The tubular telescopic component threadedly connected to the screw rod can perform linear telescopic movement along the central axis of the screw rod, that is, the tubular telescopic component translates along the axial direction of the screw rod to extend or retract, thereby driving the object connected to the end of the tubular telescopic component to move; during the retraction process of the tubular telescopic component, if the object connected to the end of the tubular telescopic component encounters an obstacle, the object can be moved. If the object is blocked, the object cannot continue to move. At the same time, the obstacle will apply a force opposite to the retraction direction to the object, that is, the tubular telescopic component will be subjected to an axial tensile load, so that the tubular telescopic component drives the screw rod to move along the central axis away from the transmission wheel, so that the transmission section and the transmission hole are no longer engaged, and then the power transmission between the transmission wheel and the screw rod is cut off, so that the transmission wheel is idle under the drive of the motor and will not drive the screw rod to rotate. The screw rod will not drive the tubular telescopic component to move, so as to prevent the tubular telescopic component from continuing to drive the object connected to it to retract and cause the squeeze of the obstacle (such as a person or an object), and to prevent the obstacle from being damaged, and also to prevent the obstacle from causing damage to the linear actuator. After the user removes the obstacle, at the moment of removing the obstacle, under the elastic force of the elastic component, the screw rod moves axially to restore the engagement between the transmission section and the transmission hole, and the user can control the linear actuator to make the tubular telescopic component continue to retract, which is convenient and simple to operate. Because the transmission section and the transmission hole can be engaged or disengaged by relatively moving a small distance in the axial direction, when the linear actuator is used as a lifting structure for objects such as a hospital bed or a desktop platform, the distance for the transmission section and the transmission hole to resume engagement is small, that is, the distance that objects such as a hospital bed or a desktop platform connected to the tubular telescopic component move downward quickly is shorter, which can avoid damage to the patient on the hospital bed or objects placed on the desktop platform, thereby ensuring the safe use of the linear actuator.
[0022] The screw includes a support section, a threaded section and a transmission section connecting the two. The transmission wheel is provided with an axially penetrating through hole, in which a transmission hole and a support hole adapted to the support section are formed. The support section penetrates the support hole and can freely shuttle and rotate in the through hole. When the transmission section of the screw moves axially to disengage from the transmission hole in the axial direction, the transmission section drives the support section to move in the support hole. The support hole guides and supports the end of the screw to prevent the screw from moving radially or shaking, so that the screw is always coaxial with the through hole, so that the transmission section and the transmission hole can quickly resume meshing in the later stage.
[0023] A relief hole is also formed in the through hole, and a first step surface is formed between the relief hole and the support hole. The elastic component is at least partially accommodated in the relief hole and is pre-tightened between the tail end of the screw rod and the first step surface. The setting of the relief hole accommodates and limits the elastic component, which is convenient for installing the elastic component and prevents the elastic component from shaking radially, ensuring that the elastic component is always pre-tightened between the screw rod and the first step surface to stably push the screw rod to reset.
[0024] The elastic component is one of a disc spring, a coil spring, and a rubber spring, or a combination thereof. The elastic component is mounted on the support section, and a stopper is provided at the tail of the screw rod to abut against the elastic component. The disc spring has the advantages of high rigidity and strong buffering and vibration absorption capabilities. It can withstand large loads with a small deformation amount. It is suitable for occasions with small axial space requirements and occupies a small space as an elastic component. The coil spring has a high elastic coefficient, a compact structure and a small mass. Its rigidity is stable and its service life can be extended as an elastic component. The rubber spring has the advantages of high internal resistance, simple structure, strong impact resistance and spring reset ability. It has a good reset effect when used as an elastic component.
[0025] A limiting hole is also formed in the through hole, and when the transmission section is in meshing state with the transmission hole, the end of the threaded section is radially limited by the limiting hole. The end of the threaded section is located in the limiting hole to limit the threaded section in the radial direction to prevent the threaded section from being displaced in the radial direction, so that the threaded section can only rotate in the limiting hole, and the operation of the screw rod is more stable and reliable.
[0026] A second step surface is formed between the limiting hole and the transmission hole, and a shoulder surface is formed at one end of the transmission section. When the transmission section and the transmission hole are axially separated, the shoulder surface abuts against the second step surface. When the transmission section and the transmission hole are meshed, the end of the threaded section abuts against the second step surface. When encountering an obstacle, the transmission section and the transmission hole are axially separated, and the shoulder surface abuts against the second step surface under the push of the elastic component. Because the shoulder surface abuts against the second step surface, there is a large friction between the shoulder surface and the second step surface. The user can control the motor to reverse through a structure such as a hand controller, and the reversed motor drives the transmission wheel to reverse. The reversed transmission wheel can drive the screw rod to reverse a certain angle through the abutted shoulder surface and the second step surface, so that the tubular telescopic component drives the object connected thereto to move a distance away from the obstacle, so as to provide a reset space for the transmission section, so that when the transmission hole is rotated to a suitable angle, the transmission section can be pushed by the elastic component to resume partial or full meshing with the transmission hole, so that the transmission wheel can drive the tubular telescopic component to extend through the screw rod to move away from the obstacle, so that the user can remove the obstacle.
[0027] The linear actuator also includes a self-locking device, which includes a first friction sleeve connected to the transmission wheel, a second friction sleeve, a self-locking torsion spring and a brake element. The brake element applies a braking torque to the second friction sleeve to limit the rotation of the second friction sleeve. The self-locking torsion spring is tightly clamped on the first friction sleeve and the second friction sleeve to form a self-locking state. The active rotation of the transmission wheel forces the self-locking torsion spring to release the first friction sleeve. When the linear actuator is extended and retracted, the self-locking torsion spring is always in a clamping state of clamping the first friction sleeve and the second friction sleeve. The motor drives the lead screw and the first friction sleeve to rotate to overcome the clamping force of the torsion spring through the transmission wheel. If the linear actuator is suddenly powered off, the motor no longer provides a driving force to overcome the clamping force of the torsion spring, and the self-locking torsion spring simultaneously clamps the first friction sleeve and the second friction sleeve, thereby preventing the lead screw from rotating, so that the lead screw forms a self-locking state, and preventing the tubular telescopic component and the object connected thereto from freely retracting by pushing the lead screw to rotate under the action of their own gravity. Furthermore, when the linear actuator is used as a lifting structure for controlling objects such as a hospital bed or a desktop platform, the objects such as the hospital bed or the desktop platform are prevented from falling rapidly when the linear actuator is powered off, thereby preventing damage to the patient on the hospital bed or the items placed on the desktop platform, thereby ensuring the safety of the linear actuator. Preferably, the first friction sleeve and the transmission wheel are an integrated structure to reduce the number of parts, reduce the difficulty of assembly, and improve assembly efficiency.
[0028] The first friction sleeve is constructed as a part of the transmission wheel so as to reduce the number of parts, lower the difficulty of assembly and improve the efficiency of assembly.
[0029] The transmission wheel includes a worm wheel and a transmission sleeve embedded in the worm wheel, a transmission hole is provided on the transmission sleeve, and one end of the transmission sleeve axially extends out of the worm wheel to form a first friction sleeve. By separately arranging the worm wheel and the transmission sleeve, and integrally arranging the first friction sleeve at the end of the transmission sleeve, the transmission wheel can not only serve as an intermediate transmission structure for the motor to drive the screw rod to rotate, but also serve as a part of the self-locking device to achieve the tightening of the screw rod when the power is suddenly cut off.
[0030] A thrust bearing is arranged between the first friction sleeve and the second friction sleeve, and the elastic component is installed at the tail of the screw and is accommodated in the avoidance space formed by the transmission sleeve and the thrust bearing. The ends of the first friction sleeve and the second friction sleeve abut against the thrust bearing, and the thrust bearing makes the relative rotation of the first friction sleeve and the second friction sleeve smoother. The transmission sleeve and the thrust bearing cooperate to form an avoidance space to avoid the elastic component installed at the tail of the screw, shorten the length of the self-locking device, the elastic component and the screw in the axial direction, and reduce the overall volume of the linear actuator.
[0031] The axial engagement length between the transmission section and the transmission hole is ≤15mm. By controlling the axial engagement length between the transmission section and the transmission hole, when the tubular telescopic component encounters an obstacle during retraction, if the user directly removes the obstacle, the transmission section quickly moves toward the transmission hole to resume engagement, and the distance can be no more than 15mm. Therefore, when the linear actuator is used as a lifting structure for controlling the lifting of objects such as hospital beds and desktop platforms, the downward impact distance of objects such as hospital beds and desktop platforms is no more than 15mm, thereby avoiding damage to patients on the hospital beds or items placed on the desktop platforms due to a long downward impact distance, thereby ensuring the safe use of the linear actuator and avoiding harm to the operator or user.
[0032] The tubular telescopic component includes a transmission nut and a tubular component. The transmission nut cooperates with the screw thread. The tubular component and the transmission nut are inseparably connected to avoid the transmission nut and the tubular component being disengaged when the linear brake encounters an obstacle during retraction, thereby avoiding damage to the tubular telescopic component and resulting in failure to transmit.
[0033] The utility model also provides a shifter, including a base and an arm rotatably connected to the base, and is characterized in that the shifter also includes the above-mentioned linear actuator, one end of the linear actuator is hinged to the base, and a tubular telescopic component is hinged to the arm, and the telescopic movement of the tubular telescopic component drives the arm to rise and fall.
[0034] The features and advantages of the present invention will be disclosed in detail in the following specific implementations and drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0035] The utility model is further described below in conjunction with the accompanying drawings and specific embodiments:
[0036] Figure 1 is a three-dimensional diagram of the linear actuator in the first embodiment;
[0037] Figure 2 It is a partial schematic diagram of the screw rod in the first embodiment;
[0038] Figure 3 is an internal schematic diagram of the linear actuator in Example 1;
[0039] Figure 4 is a cross-sectional view of the transmission section and the transmission hole of the linear actuator in the first embodiment when they are engaged;
[0040] Figure 5 A cross-sectional view of the axial separation of the transmission section and the transmission hole of the linear actuator in Example 1
[0041] Figure 6 A three-dimensional diagram of the transmission sleeve in the first embodiment
[0042] Figure 7 is a cross-sectional view of the transmission sleeve in the first embodiment;
[0043] Figure 8 It is a three-dimensional diagram of the shifter in the second embodiment.
[0044] Reference numerals:
[0045] 100, motor; 110, output shaft;
[0046] 200, transmission wheel; 210, through hole; 211, avoidance hole; 212, support hole; 213, transmission hole; 214, limit hole; 215, first step surface; 216, second step surface; 220, worm wheel; 230, transmission sleeve;
[0047] 300, screw rod; 310, support section; 311, stopper; 320, transmission section; 321, shaft shoulder surface; 330, threaded section;
[0048] 400, tubular telescopic member; 410, transmission nut; 420, tubular member;
[0049] 500, elastic component;
[0050] 600, self-locking device; 610, first friction sleeve; 620, second friction sleeve; 630, self-locking torsion spring; 640, braking element; 650, thrust bearing.
[0051] 700, housing; 710, outer tube;
[0052] 810, base; 820, boom. DETAILED DESCRIPTION
[0053] The following is an explanation and description of the technical scheme of the embodiment of the utility model in conjunction with the drawings of the embodiment of the utility model, but the following embodiment is only a preferred embodiment of the utility model, not all. Based on the embodiment in the implementation mode, other embodiments obtained by those skilled in the art without creative work are all within the protection scope of the utility model.
[0054] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.
[0055] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present utility model, unless otherwise specified, "plurality" means two or more, unless otherwise clearly defined.
[0056] In the present invention, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0057] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.
[0058] Embodiment 1:
[0059] Linear actuators, such as Figures 1 to 7As shown, it includes a housing 700 and a motor 100, a transmission wheel 200, a screw rod 300, a tubular telescopic component 400 and an elastic component 500 arranged in the housing 700. The motor 100 is provided with an output shaft 110, and the output shaft 110 cooperates with the outer peripheral side of the transmission wheel 200 to drive the transmission wheel 200 to rotate. The transmission wheel 200 is provided with a transmission hole 213 that penetrates the transmission wheel 200. The screw rod 300 is penetrated in the transmission hole 213 to be coaxially arranged with the transmission wheel 200. The screw rod 300 has a transmission section 320, and the transmission section 320 can be engaged in the transmission hole 213 to keep the transmission wheel 200 and the screw rod 300 rotating synchronously along the circumferential direction. The transmission section 320 can also be moved along the axial direction of the transmission wheel 200 so that the transmission section 320 is no longer engaged with the transmission hole 213, thereby cutting off the power transmission between the transmission wheel 200 and the screw rod 300. The housing 700 has a fixed outer tube 710, and the tubular telescopic component 400 is arranged in the outer tube 710 and is threadedly connected to the screw rod 300. When the linear actuator is used, because one end of the linear actuator is fixed and the other end is connected to a heavy object such as a hospital bed, a table platform, etc., the two ends of the linear actuator are restricted from rotating, that is, the tubular telescopic component 400 is restricted from rotating. When the screw rod 300 rotates, the tubular telescopic component 400 can perform linear telescopic movement along the central axis of the screw rod 300, that is, the tubular telescopic component 400 translates along the axial direction of the screw rod 300 to extend or retract the outer tube 710, thereby driving the object (a hospital bed, a table platform, etc.) connected to the end of the tubular telescopic component 400 to move. The elastic component 500 abuts against the screw rod 300 to push the screw rod 300 in the retracting direction of the tubular telescopic component 400, so that the screw rod 300 maintains its force state in the retracting direction of the tubular telescopic component 400.
[0060] The utility model is provided with the screw rod 300 through the transmission hole 213 of the transmission wheel 200, and the screw rod 300 is set to a structure that can move along the axial direction of the transmission wheel 200, so that the screw rod 300 can maintain a meshing state with the transmission hole 213 under the push of the elastic component 500. At this time, the output shaft 110 of the motor 100 drives the transmission wheel 200 to rotate, and the transmission wheel 200 drives the screw rod 300 to rotate synchronously through the meshing transmission hole 213 and the transmission section 320. The tubular telescopic component 400 threadedly connected to the screw rod 300 can perform linear telescopic movement along the central axis of the screw rod 300, that is, the tubular telescopic component 400 translates along the axial direction of the screw rod 300 to extend or retract, thereby driving the object connected to the end of the tubular telescopic component 400 to move; during the retraction of the tubular telescopic component 400, if the object connected to the tubular telescopic component 400 is 00, if the object at the end thereof encounters an obstacle, the object cannot continue to move, and the obstacle will apply a force opposite to the retraction direction to the object, that is, the tubular telescopic component 400 will be subjected to an axial tensile load, so that the tubular telescopic component 400 drives the screw rod 300 to move along the central axis to the side away from the transmission wheel 200, so that the transmission section 320 and the transmission hole 213 are no longer engaged, thereby cutting off the power transmission between the transmission wheel 200 and the screw rod 300, so that the transmission wheel 200 idles under the drive of the motor 100, and will not drive the screw rod 300 to rotate, and the screw rod 300 will not drive the tubular telescopic component 400 to move, thereby preventing the tubular telescopic component 400 from continuing to drive the object connected thereto to retract and causing squeezing of the obstacle (such as a person or object), thereby preventing the obstacle from being damaged and also preventing the obstacle from causing damage to the linear actuator. After the user removes the obstacle, at the moment of removing the obstacle, under the elastic force of the elastic component 500, the screw rod 300 moves axially to restore the engagement between the transmission section 320 and the transmission hole 213, and the user can control the linear actuator to make the tubular telescopic component 400 continue to retract, which is convenient and simple to operate. Because the transmission section 320 and the transmission hole 213 can be engaged or disengaged by relatively moving a small distance in the axial direction, when the linear actuator is used as a lifting structure for objects such as a hospital bed or a desktop platform, the distance for the transmission section 320 to restore the engagement with the transmission hole 213 is small, that is, the distance for the objects such as the hospital bed or the desktop platform connected to the tubular telescopic component 400 to move downward quickly is short, which can avoid damage to the patient on the hospital bed or the items placed on the desktop platform, thereby ensuring the safety of the use of the linear actuator.
[0061] like Figure 2 As shown, the screw rod 300 includes a supporting section 310, a transmission section 320 and a threaded section 330, the transmission section 320 is connected between the supporting section 310 and the threaded section 330, the outer diameter of the transmission section 320 is larger than the outer diameter of the supporting section 310, and the outer diameter of the threaded section 330 is larger than the outer diameter of the transmission section 320.
[0062] like Figure 7As shown, a through hole 210 is provided on the transmission wheel 200 and axially penetrates the transmission wheel 200. The through hole 210 is coaxial with the transmission wheel 200, and a transmission hole 213 and a support hole 212 are formed in the through hole 210 and are adjacent to each other. Figure 4 As shown, when the screw rod 300 is engaged with the transmission wheel 200, the transmission section 320 is inserted in the transmission hole 213 and engages with the inner wall of the transmission hole 213 to maintain circumferential linkage, and the support section 310 is inserted in the support hole 212 and can freely shuttle and rotate in the through hole 210. In the process of the transmission section 320 of the screw rod 300 moving axially to disengage from the transmission hole 213 in the axial direction, the transmission section 320 drives the support section 310 to move in the support hole 212. The support hole 212 cooperates with the support section 310 to guide and support the end of the screw rod 300 to prevent the screw rod 300 from radial movement or shaking, so that the screw rod 300 is always coaxial with the through hole 210, so as to facilitate the transmission section 320 to quickly resume engagement with the transmission hole 213 in the later stage.
[0063] like Figure 7 As shown, an avoidance hole 211 is also formed in the through hole 210, and the avoidance hole 211 is located at one end of the support hole 212 away from the transmission hole 213. The inner diameter of the avoidance hole 211 is larger than the inner diameter of the support hole 212, so as to form a first step surface 215 at the connection between the avoidance hole 211 and the support hole 212. The elastic component 500 is partially or completely arranged in the avoidance hole 211, and the two ends of the elastic component 500 are respectively abutted against the first step surface 215 and the tail end of the screw rod 300, so that the elastic component 500 is pre-tightened between the tail end of the screw rod 300 and the first step surface 215, so that the elastic component 500 can push the transmission section 320 of the screw rod 300 to reset to the transmission hole 213. The setting of the avoidance hole 211 accommodates and limits the elastic component 500, which facilitates the installation of the elastic component 500 and prevents the elastic component 500 from radially shaking, ensuring that the elastic component 500 is always pre-tightened between the screw rod 300 and the first step surface 215 to stably push the screw rod 300 to reset.
[0064] In this embodiment, the elastic component 500 can be one of a disc spring, a coil spring, and a rubber spring. The disc spring has the advantages of high stiffness and strong buffering and vibration absorption capabilities. It can withstand large loads with a small deformation amount and is suitable for occasions where small axial space requirements are required. As an elastic component 500, it occupies a small space. The coil spring has a high elastic coefficient, a compact structure and a small mass. Its stiffness is stable. As an elastic component 500, its service life can be extended. The rubber spring has the advantages of high internal resistance, simple structure, impact resistance and strong spring reset ability. When used as the elastic component 500, it has a good reset effect. Of course, the elastic component 500 can also be a combination of any two or three of the disc spring, coil spring and rubber spring. Figure 4 and Figure 5As shown, the elastic component 500 is sleeved on the part of the support section 310 extending into the avoidance hole 211 to limit the elastic component 500, and a stopper 311 coaxially arranged with the screw rod 300 is provided at the tail end of the screw rod 300, and the stopper 311 is fixed on the support section 310. The outer diameter of the stopper 311 is larger than the outer diameter of the support section 310, so as to abut the end of the elastic component 500, so that the two ends of the elastic component 500 respectively abut against the stopper 311 and the first step surface 215.
[0065] like Figure 7 As shown, a limiting hole 214 is also formed in the through hole 210. The limiting hole 214 is located at one end of the transmission hole 213 away from the support hole 212. When the transmission section 320 is engaged with the transmission hole 213, the end of the threaded section 330 is located in the limiting hole 214, so as to limit the threaded section 330 in the radial direction to avoid radial displacement of the threaded section 330, so that the threaded section 330 can only rotate in the limiting hole 214, and the operation of the screw rod 300 is more stable and reliable. The cross-sectional area of the limiting hole 214 is larger than the cross-sectional area of the transmission hole 213, so that a second step surface 216 is formed at the connection between the limiting hole 214 and the transmission hole 213, and a shoulder surface 321 is formed at one end of the transmission section 320 close to the support section 310. When the transmission section 320 is engaged with the transmission hole 213, the end of the threaded section 330 abuts against the second step surface 216. When encountering an obstacle, such as Figure 5 As shown, the transmission section 320 and the transmission hole 213 are axially separated, and the shoulder surface 321 is pushed by the elastic component 500 to abut against the second step surface 216. Because the shoulder surface 321 abuts against the second step surface 216, there is a large friction force between the shoulder surface 321 and the second step surface 216. The user can control the motor 100 to reverse through a structure such as a hand controller, and the reversed motor 100 drives the transmission wheel 200 to reverse. The reversed transmission wheel 200 can reverse through the abutting shoulder surface 321 and the second step surface 21 6 drives the screw rod 300 to reverse a certain angle, so that the tubular telescopic component 400 drives the object connected thereto to move a certain distance in the direction away from the obstacle, providing a reset space for the transmission section 320. When the transmission hole 213 rotates to a suitable angle, the transmission section 320 can restore partial or full engagement with the transmission hole 213 under the push of the elastic component 500, so that the transmission wheel 200 can drive the tubular telescopic component 400 to extend to move away from the obstacle through the screw rod 300, so that the user can move the obstacle away.
[0066] In this embodiment, the transmission section 320 can be set as a non-circular shaft, and the transmission hole 213 can be set as a non-circular shaft hole. The non-circular shaft and the non-circular shaft hole can be matched to make the transmission section 320 and the transmission hole 213 linked in the circumferential direction; matching keys and keyways can also be set on the outer wall of the transmission section 320 and the inner wall of the transmission hole 213 respectively to achieve the circumferential linkage between the transmission section 320 and the transmission hole 213, which is convenient and simple to install and has a good transmission effect between the transmission wheel 200 and the screw rod 300.
[0067] In an embodiment, Figure 3 As shown, the linear actuator further includes a self-locking device 600, which includes a first friction sleeve 610, a second friction sleeve 620, a self-locking torsion spring 630 and a brake element 640. The first friction sleeve 610 is fixedly connected to the transmission wheel 200 so that the first friction sleeve 610 and the transmission wheel 200 are linked. The second friction sleeve 620 is located on the side of the first friction sleeve 610 away from the transmission wheel 200. The first friction sleeve 610 and the second friction sleeve 620 are arranged adjacent to each other. The brake element 640 is fixed on the housing 700 to apply a braking torque to the second friction sleeve 620 to limit the rotation of the second friction sleeve 620. Preferably, the brake element 640 adopts a friction pad, the end surface of the friction pad is in contact with the second friction sleeve 620, and the friction force generated by the contact between the friction pad and the second friction sleeve 620 provides a braking torque for the second friction sleeve 620.
[0068] When the linear actuator is extended and retracted, the self-locking torsion spring 630 is always in a state of holding the first friction sleeve 610 and the second friction sleeve 620, and the motor 100 drives the screw rod 300 and the first friction sleeve 610 to rotate by overcoming the holding force of the torsion spring through the transmission wheel 200; if the linear actuator is suddenly powered off, the motor 100 no longer provides a driving force to overcome the holding force of the torsion spring, and the self-locking torsion spring 630 simultaneously holds the first friction sleeve 610 and the second friction sleeve 620, thereby preventing the screw rod 300 from rotating, so that the screw rod 300 forms a self-locking state, and preventing the tubular telescopic component 400 and the object connected thereto from freely retracting by pushing the screw rod 300 to rotate under the action of their own gravity. Furthermore, when the linear actuator is used as a lifting structure for controlling objects such as a hospital bed or a desktop platform, the objects such as the hospital bed or the desktop platform are prevented from falling rapidly when the linear actuator is powered off, and damage to the patient on the hospital bed or the objects placed on the desktop platform is avoided, thereby ensuring the safety of the use of the linear actuator. Preferably, the first friction sleeve 610 and the transmission wheel 200 are an integrated structure, so as to reduce the number of parts, reduce the difficulty of assembly, and improve the assembly efficiency.
[0069] A thrust bearing 650 is arranged between the first friction sleeve 610 and the second friction sleeve 620. The ends of the first friction sleeve 610 and the second friction sleeve 620 abut against the thrust bearing 650 to clamp the thrust bearing 650 together. The thrust bearing 650 makes the relative rotation of the first friction sleeve 610 and the second friction sleeve 620 smoother. The transmission sleeve 230 and the thrust bearing 650 cooperate to form an escape space to avoid the elastic component 500 installed at the tail of the screw rod 300, shorten the axial length of the self-locking device 600, the elastic component 500 and the screw rod 300, and reduce the overall volume of the linear actuator. When the transmission section 320 and the transmission hole 213 are engaged, the end of the threaded section 330 abuts against the second step surface 216, which can prevent the end of the screw rod 300 from excessively extending into the escape space and affecting the operation of the self-locking device 600.
[0070] The transmission wheel 200 in this embodiment can be an integral structure or a split structure. Preferably, the transmission wheel 200 includes a separately arranged worm wheel 220 and a transmission sleeve 230, the transmission sleeve 230 is nested in the worm wheel 220, and the transmission hole 213 is arranged on the transmission sleeve 230. One end of the transmission sleeve 230 axially extends out of the worm wheel 220 to form a first friction sleeve 610. By separately arranging the worm wheel 220 and the transmission sleeve 230, and integrally arranging the first friction sleeve 610 at the end of the transmission sleeve 230, the transmission wheel 200 can not only serve as an intermediate transmission structure for the motor 100 to drive the screw rod 300 to rotate, but also can serve as a part of the self-locking device 600 to achieve the clamping of the screw rod 300 when the power is suddenly cut off.
[0071] It can be understood from the above self-locking principle that the self-locking of the self-locking torsion spring 630 is based on the friction braking principle. Friction heat will be generated between the self-locking torsion spring 630 and the first friction sleeve 610. This heat generation will have an adverse effect on the dimensional stability of the worm wheel 220. In this embodiment, the transmission wheel 200 is set as a structure in which the worm wheel 220 and the transmission sleeve 230 are separately set, and the transmission sleeve 230 is nested in the worm wheel 220, so that the worm wheel 220 and the transmission sleeve 230 can be selected from different materials respectively. The first friction sleeve 610 is integrally set at the end of the transmission sleeve 230. The transmission sleeve 230 not only bears the role of transmitting torque, but also plays a role of heat insulation, weakening the friction heat transmitted from the first friction sleeve 610 to the worm wheel 220. More advantageously, the transmission hole 213 is also set on the transmission sleeve 230, which can achieve a high degree of integration of the transmission structure and the self-locking structure, and can be installed and used in the narrow space at the tail of the linear actuator.
[0072] The axial engagement length between the transmission section 320 and the transmission hole 213 is less than or equal to 15 mm. By controlling the axial engagement length between the transmission section 320 and the transmission hole 213, when the tubular telescopic component 400 retracts and encounters an obstacle, if the user directly removes the obstacle, the distance that the transmission section 320 quickly moves toward the transmission hole 213 to restore the engagement can be no more than 15 mm. Therefore, when the linear actuator is used as a lifting structure for controlling the lifting of objects such as a hospital bed and a desktop platform, the downward impact distance of objects such as the hospital bed and the desktop platform is no more than 15 mm, thereby avoiding damage to the patient on the hospital bed or the items placed on the desktop platform due to a long downward impact distance, ensuring the safety of the use of the linear actuator and avoiding harm to the operator or user. Preferably, the axial engagement length between the transmission section 320 and the transmission hole 213 is 10 mm.
[0073] In this embodiment, the transmission section 320 extends backward from the tail of the threaded section 330, and the length of the transmission hole 213 is greater than the length of the transmission section 320. After the transmission section 320 re-engages with the transmission hole 213, the tail of the threaded section 330 abuts against the second step surface 216. The axial engagement length of the transmission section 320 and the transmission hole 213 is the axial length of the transmission section 320, which can be pre-designed, which is very different from the prior art. When the previous linear actuator is used as a lifting structure, when the tubular structure is disengaged from the lead screw nut, the lead screw nut can still be driven downward by the lead screw due to friction, and the downward movement is uncontrollable, which may cause the tubular structure to produce a large stroke fall impact. This embodiment limits the axial engagement length of the transmission section 320 and the transmission hole 213 to be less than or equal to 15 mm, that is, the lead screw fall impact distance will not be greater than 15 mm. The controllable fall impact distance reduces human perception and ensures the safety of the linear actuator.
[0074] The tubular telescopic component 400 includes a transmission nut 410 and a tubular component 420. The transmission nut 410 is threadedly matched with the lead screw 300. The tubular component 420 and the transmission nut 410 are inseparably connected, so that when the linear brake encounters an obstacle in retracting, the transmission nut 410 and the tubular component 420 cannot be disengaged, thereby avoiding damage to the tubular telescopic component 400 and causing failure to transmit. It should be noted that the inseparability here is intended to indicate that the transmission nut 410 and the tubular component 420 will not be separated from each other due to axial tension, but this does not limit the specific connection structure. For example, the transmission nut 410 and the tubular component 420 can be connected by thread, snap connection, etc., which can be used to resist axial tension.
[0075] Embodiment 2:
[0076] A shifter, such as Figure 8As shown, it includes a base 810 and an arm 820, the arm 820 is rotatably connected to the base 810, and also includes the linear actuator in Example 1, the shell 700 at one end of the linear actuator is hinged to the base 810, and the tubular telescopic component 400 of the linear actuator is hinged to the arm 820, so that the arm 820 can be raised and lowered by the telescopic movement of the tubular telescopic component 400 of the linear actuator.
[0077] The above is only a preferred embodiment of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.
Claims
1. A linear actuator, characterized in that include: Motor; A transmission wheel, driven to rotate by the motor; A screw rod, driven to rotate by the transmission wheel; The tubular telescopic component is driven by the rotational motion of the screw rod to perform linear telescopic motion; Wherein, the transmission wheel includes a transmission hole, the screw rod includes a transmission section, the transmission section is meshed in the transmission hole and keeps the two rotating synchronously in the circumferential direction and can move axially relative to each other, so as to allow the screw rod to move in the extension direction of the tubular telescopic component when subjected to an axial tensile load, so that the transmission section and the transmission hole are axially separated, and the power transmission between the transmission wheel and the screw rod is cut off; The elastic component acts on the screw rod to keep the screw rod in a stressed state in the direction of retracting the tubular telescopic component.
2. The linear actuator according to claim 1, characterized in that: The screw rod includes a supporting section, a threaded section and the transmission section connecting the two. The transmission wheel is provided with an axially penetrating through hole, in which the transmission hole and the supporting hole adapted to the supporting section are formed. The supporting section penetrates the supporting hole and can freely shuttle and rotate in the through hole.
3. The linear actuator according to claim 2, characterized in that: An avoidance hole is also formed in the through hole, and a first step surface is formed between the avoidance hole and the support hole. The elastic component is at least partially accommodated in the avoidance hole and is pre-tightened between the tail end of the screw rod and the first step surface.
4. The linear actuator according to claim 3, characterized in that: The elastic component is one of a disc spring, a spiral spring, and a rubber spring, or a combination thereof. The elastic component is sleeved on the support section, and a stopper abutting against the elastic component is provided at the tail of the screw rod.
5. The linear actuator according to claim 2, characterized in that: A limiting hole is also formed in the through hole, and when the transmission section is in meshing state with the transmission hole, the end of the threaded section is radially limited by the limiting hole.
6. The linear actuator according to claim 5, characterized in that: A second step surface is formed between the limiting hole and the transmission hole, and a shoulder surface is formed at one end of the transmission section. When the transmission section and the transmission hole are axially separated, the shoulder surface abuts against the second step surface.
7. The linear actuator according to claim 1, characterized in that: The linear actuator also includes a self-locking device, which includes a first friction sleeve connected to the transmission wheel, a second friction sleeve, a self-locking torsion spring and a braking element. The braking element applies a braking torque to the second friction sleeve to limit the rotation of the second friction sleeve. The self-locking torsion spring is tightly attached to the first friction sleeve and the second friction sleeve to form a self-locking state. The active rotation of the transmission wheel forces the self-locking torsion spring to release the first friction sleeve.
8. The linear actuator according to claim 7, characterized in that: The first friction sleeve is designed as a part of the drive wheel.
9. The linear actuator according to claim 8, characterized in that: The transmission wheel comprises a worm wheel and a transmission sleeve embedded in the worm wheel, the transmission hole is arranged on the transmission sleeve, and one end of the transmission sleeve axially extends out of the worm wheel to form the first friction sleeve.
10. The linear actuator according to claim 9, characterized in that: A thrust bearing is arranged between the first friction sleeve and the second friction sleeve. The elastic component is installed at the tail of the screw rod and is accommodated in an avoidance space formed by the cooperation of the transmission sleeve and the thrust bearing.
11. The linear actuator according to any one of claims 1 to 10, characterized in that: The transmission section and the transmission hole form a non-circular shaft hole fit or a keyway fit.
12. The linear actuator according to any one of claims 1 to 10, characterized in that: The axial engagement length between the transmission section and the transmission hole is ≤15mm.
13. The linear actuator according to any one of claims 1 to 10, characterized in that: The tubular telescopic component comprises a transmission nut and a tubular component. The transmission nut is threadably matched with the lead screw. The tubular component and the transmission nut are inseparably connected.
14. A shifter comprising a base and a suspension arm rotatably connected to the base, characterized in that: The shifter also includes a linear actuator as described in any one of claims 1 to 13, one end of the linear actuator is hinged to the base, the tubular telescopic component is hinged to the boom, and the telescopic movement of the tubular telescopic component drives the boom to rise and fall.