CN118602082A - Linear Actuators and Displacers - Google Patents

Abstract

The present invention discloses a linear actuator and a shifter, including: a motor; a transmission assembly; a screw rod; a tubular telescopic component; a front pull assembly, which is installed at the end of the tubular telescopic component through a clutch assembly; wherein the clutch assembly includes a first joint, a second joint and an elastic component, and the first joint and the second joint are relatively fixed in the circumferential direction and can move relative to each other in the axial direction when they are engaged, and the tubular telescopic component can rotate independently when the first joint and the second joint are axially separated. The present invention arranges a clutch assembly between the front pull assembly and the tubular telescopic component, and arranges the clutch assembly into a structure in which the first joint, the second joint and the elastic component cooperate, so that if the tubular telescopic component encounters an obstacle during the retraction process, the second joint is axially separated from the first joint, and the tubular telescopic component idles, thereby preventing the tubular telescopic component from continuing to drive the object connected to the front pull assembly to retract and causing the obstacle to be squeezed, and also preventing the obstacle from damaging the linear actuator.

Description

Linear Actuators and Displacers

Technical Field

The invention belongs to the field of linear driving, and in particular relates to a linear actuator and a shifter.

Background Art

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.

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.

Summary of the invention

The technical problem to be solved by the present invention is to provide a linear actuator to solve the problem of damage caused by obstacles when the linear actuator drives an object to retract.

In order to solve the above technical problems, the present invention adopts the following technical solutions: a linear actuator, comprising: a motor; a transmission assembly; a screw rod, driven to rotate by the motor power transmitted by the transmission assembly; a tubular telescopic component, driven by the rotational movement of the screw rod to perform linear telescopic movement; a front pull assembly, installed on the end of the tubular telescopic component through a clutch assembly; wherein the clutch assembly comprises a first joint connected to the tubular telescopic component, a second joint connected to the front pull assembly, and an elastic component that provides a thrust for the engagement of the two, wherein the first joint and the second joint remain relatively fixed in the circumferential direction when engaged and can move axially relative to each other, so as to allow the front pull assembly to drive the second joint and the first joint to separate axially when subjected to an axial tensile load, and when the first joint and the second joint are in an axially separated state, the tubular telescopic component can rotate independently.

In the above-mentioned linear actuator, the second joint has a connecting shaft, the first joint has a shaft connecting hole, the shaft connecting hole is for the connecting shaft to pass through and connect, a first axial stop is arranged in the shaft connecting hole, a second axial stop is arranged on the connecting shaft, and the elastic component is installed on the connecting shaft and is pre-tightened between the first axial stop and the second axial stop.

In the above linear actuator, the shaft connection hole includes a small diameter hole, a large diameter hole and a step surface connecting the two, the small diameter hole guides the axial displacement of the connecting shaft, and the elastic component is accommodated in the large diameter hole and abuts against the step surface constituting the first axial stop.

In the above-mentioned linear actuator, the second axial stop includes a fastener and a thrust bearing. The thrust bearing is installed on the connecting shaft through the fastener, and the elastic component is against the thrust bearing. When the first joint and the second joint are axially separated, the thrust bearing maintains the independent rotation of the first joint.

In the above linear actuator, the fastener is threadedly connected to the connecting shaft and is used to adjust the preload force of the elastic component.

In the above linear actuator, the elastic component is one of a disc spring, a coil spring, and a rubber spring, or a combination thereof.

In the above linear actuator, the first joint and the second joint adopt ratchet engagement or spline engagement.

In the above-mentioned linear actuator, the front pulling assembly includes a front pulling head and a hand-twist releasing device, and the hand-twist releasing device includes: a first connecting body connected to the front pulling head; a second connecting body connected to the tubular telescopic component, the second connecting body is nested in the first connecting body and the two form a rotatable axial positioning; a brake torsion spring, which is pressed against the inner surface of the first connecting body, and one end of the brake torsion spring is fixed to the second connecting body; an operating handle, which is constructed as a sleeve structure and is assembled outside the first connecting body, and rotating the operating handle is used to drive the brake torsion spring to retract and release the first connecting body and can drive the second connecting body to rotate.

In the above linear actuator, the second connecting body and the second joint are constructed as an integral structure.

In the above linear actuator, an axial engagement length of the first joint and the second joint is ≤15 mm.

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.

The beneficial effects of the present invention are:

The linear actuator includes: a motor; a transmission assembly; a screw rod, which is driven to rotate by the motor power transmitted by the transmission assembly; a tubular telescopic component, which is driven by the rotational movement of the screw rod to perform linear telescopic movement; a front pull assembly, which is installed at the end of the tubular telescopic component through a clutch assembly; wherein the clutch assembly includes a first joint connected to the tubular telescopic component, a second joint connected to the front pull assembly, and an elastic component that provides the engagement thrust between the two. When the first joint and the second joint are engaged, they remain relatively fixed in the circumferential direction and can move axially relative to each other, so as to allow the front pull assembly to drive the second joint and the first joint to separate axially when subjected to an axial tensile load. When the first joint and the second joint are axially separated, the tubular telescopic component can rotate independently. This technical solution has the following technical effects:

The present invention sets a clutch assembly between the front pulling assembly and the tubular telescopic component, and sets the clutch assembly into a structure in which the first joint, the second joint and the elastic component cooperate, so that during the retraction of the tubular telescopic component, if the object connected to the end of the tubular telescopic component encounters an obstacle, the object cannot continue to move, and at the same time the obstacle will apply a force opposite to the retraction direction to the object, that is, the front pulling assembly will be subjected to an axial tensile load, so that the second joint is separated from the first joint along the axial direction, and the first joint is no longer relatively fixed with the second joint in the circumferential direction, that is, the second joint and the front pulling assembly no longer limit the tubular telescopic component in the circumferential direction. At this time, the rotating screw can drive the tubular telescopic component and the first joint connected to the tubular telescopic component to idle, so as to prevent the tubular telescopic component from continuing to drive the object connected to the front pulling assembly to retract and causing squeezing of the obstacle (such as a person or an object), thereby preventing the obstacle from being damaged and also preventing the obstacle from damaging the linear actuator. After encountering an obstacle, the user can control the motor to reverse through a hand controller or other structures to drive the screw to rotate in the opposite direction. While the tubular telescopic component rotates driven by the screw, due to the friction between the two and the pull of the elastic component on the first joint, the tubular telescopic component simultaneously moves slightly toward the direction of the second joint, so that the first joint and the second joint are re-engaged, so that the second joint re-limits the tubular telescopic component in the circumferential direction through the first joint, and then the tubular telescopic component drives the front pull assembly to move away from the obstacle through the first joint and the second joint, so that the user can remove the obstacle. Of course, the user can also directly remove the obstacle. At the moment of removing the obstacle, under the elastic force of the elastic component, the second joint moves toward the first joint to resume engagement with the first joint. The user can control the tubular telescopic component of the linear actuator to continue to retract, which is convenient and simple to operate. Because there is an engaging structure between the first joint and the second joint, the engaging structure allows the first joint and the second joint to be disengaged by 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 second joint to resume engagement with the first joint is small, that is, the distance of the rapid downward impact of objects such as a hospital bed or a desktop platform connected to the front pull assembly after the obstacle is removed can be controlled within a short range, thereby avoiding damage to the patient on the hospital bed or the items placed on the desktop platform, thereby ensuring the safe use of the linear actuator.

The second joint has a connecting shaft, and the first joint has a shaft connection hole, the shaft connection hole is for the connecting shaft to pass through and connect, a first axial stop is arranged in the shaft connection hole, a second axial stop is arranged on the connecting shaft, and the elastic component is installed on the connecting shaft and pre-tightened between the first axial stop and the second axial stop. The cooperation between the connecting shaft and the shaft connection hole can guide the first joint and the second joint, so that the two can only move relative to each other along the axial direction, and the operation is stable. At the same time, it is convenient to install the elastic component, and the elastic component is hidden in the shaft connection hole of the first joint.

The shaft connection hole includes a small diameter hole, a large diameter hole and a step surface connecting the two. The small diameter hole guides the axial displacement of the connecting shaft, and the elastic component is received in the large diameter hole and abuts against the step surface constituting the first axial stop. By setting the shaft connection hole to a structure in which the small diameter hole and the large diameter hole cooperate, the shaft connection hole can not only guide the connecting shaft in the axial direction and limit the connection shaft in the radial direction through the small diameter hole, thereby ensuring the stable movement of the connecting shaft in the shaft connection hole, but also accommodate the elastic component through the large diameter hole. At the same time, the step surface formed between the small diameter hole and the large diameter hole can also serve as a stop structure for the end of the elastic component, thereby reducing the difficulty of processing and manufacturing the first joint.

The second axial stop includes a fastener and a thrust bearing. The thrust bearing is installed on the connecting shaft through the fastener. The elastic component is against the thrust bearing. When the first joint and the second joint are axially separated, the thrust bearing maintains the independent rotation of the first joint. When the first joint and the second joint move relative to each other in the axial direction to separate, the thrust bearing of the second axial stop and the step surface of the first axial stop jointly squeeze the elastic component to gradually compress the elastic component, thereby increasing the friction between the two ends of the elastic component and the first axial stop and the second axial stop. Because the elastic component is against the rotatable end face of the thrust bearing on the connecting shaft, the thrust bearing can ensure that the connecting shaft will not hinder the rotation of the elastic component due to the large friction between the second axial stop and the elastic component. That is, when the first joint and the second joint are in an axially separated state, the tubular telescopic component rotates to drive the first joint to rotate, and the first joint drives the elastic component to rotate together through the large friction between the step surface and the elastic component. The half circle of the thrust bearing close to the elastic component rotates together with the elastic component, avoiding the friction between the second axial stop and the elastic component at the end of the connecting shaft to hinder the rotation of the first joint, ensuring that the elastic component can rotate smoothly relative to the connecting shaft, thereby avoiding the situation where the tubular telescopic component is difficult to rotate due to the large friction between the second axial stop and the elastic component.

The fastener is threadedly connected to the connecting shaft and is used to adjust the preload force of the elastic component. The distance between the thrust bearing and the step surface is adjusted by adjusting the axial position of the thrust bearing on the connecting shaft, and then the preload force of the elastic component is adjusted to ensure the pushing effect of the elastic component on the second joint.

The elastic component is one of a disc spring, a coil spring, and a rubber spring, or a combination thereof. The disc spring has the advantages of high rigidity and strong buffering and vibration absorption capability, can bear large loads with a small deformation, 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, and its rigidity is stable. As an elastic component, its service life can be extended. The rubber spring has the advantages of high internal resistance, simple structure, strong impact bearing capacity, and strong spring reset capability. When used as an elastic component, it has a good reset effect of pushing the second joint.

The first joint and the second joint adopt ratchet engagement or spline engagement. The ratchet engagement makes the installation between the first joint and the second joint more convenient and simple, and the spline engagement can make the transmission effect between the first joint and the second joint good and the bearing capacity of the clutch assembly strong.

The front pulling assembly includes a front pulling head and a hand-twist releasing device, and the hand-twist releasing device includes: a first connecting body connected to the front pulling head; a second connecting body connected to the tubular telescopic component, the second connecting body is nested in the first connecting body and the two form a rotatable axial positioning; a braking torsion spring, which is pressed against the inner surface of the first connecting body, and one end of the braking torsion spring is fixed to the second connecting body; an operating handle, which is constructed as a sleeve structure and is assembled outside the first connecting body, and rotating the operating handle is used to drive the braking torsion spring to retract and release the first connecting body and can drive the second connecting body to rotate. When the linear actuator is working normally, the lead screw drives the tubular telescopic part threadedly connected to it to extend and retract by rotating, and the tubular telescopic part drives the second connecting body to move through the meshing first joint and second joint, thereby driving the first connecting body and the front pulling head connected to objects such as the bed and the desktop platform to move. At this time, the brake torsion spring abuts against the inner surface of the first connecting body and does not contact the outer surface of the second connecting body; when the linear actuator suddenly loses power, the lead screw is clamped by the self-locking structure to prevent the tubular telescopic part from retracting. The user can rotate the operating handle so that the brake torsion spring clamps the second connecting body and no longer abuts against the inner wall of the first connecting body. At this time, the operating handle can drive the second connecting body to rotate relative to the first connecting body, the second connecting body drives the second joint to rotate, and the second joint drives the first joint to rotate, thereby driving the tubular telescopic part to rotate relative to the lead screw, so that the tubular telescopic part moves in the direction of retraction along the central axis of the lead screw, and the tubular telescopic part pulls the clutch assembly, the front pulling assembly and the object connected to the front pulling assembly to move together to achieve retraction. When the linear actuator is used as a lifting structure to control the lifting of objects such as hospital beds and desktop platforms, the user can turn the operating handle of the hand-screw release device by himself to lower the hospital beds, desktop platforms and other objects that have risen or fallen into mid-air, thereby improving the user experience.

The second connector and the second joint are constructed as an integrated structure, so as to reduce the number of parts, reduce the difficulty of assembly, and improve the efficiency of assembly.

The axial engagement length of the first joint and the second joint is ≤15mm. By controlling the axial engagement length of the first joint and the second joint, when the tubular telescopic component encounters an obstacle during retraction, if the user directly removes the obstacle, the distance at which the second joint quickly moves toward the first joint to resume engagement with the first joint can be maintained at about 15mm. Therefore, when the linear actuator is used as a lifting structure to control 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 small and controllable, avoiding damage to patients on the hospital beds or items placed on the desktop platform due to a long downward impact distance, thereby ensuring the safety of the use of the linear actuator and avoiding harm to the operator or user.

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 being disengaged from the tubular component when the linear brake encounters an obstacle during retraction, thereby avoiding damage to the tubular telescopic component and resulting in failure to transmit.

The present invention also provides a shifter, including a base and an arm rotatably connected to the base. 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. The telescopic movement of the tubular telescopic component drives the arm to rise and fall.

The features and advantages of the present invention will be disclosed in detail in the following specific embodiments and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments:

FIG1 is a perspective view of a linear actuator in Embodiment 1;

FIG2 is a cross-sectional view of the linear actuator in Embodiment 1;

FIG3 is an internal schematic diagram of the linear actuator in Embodiment 1;

FIG4 is an assembly diagram of the front pull assembly and the clutch assembly in the first embodiment;

FIG5 is a cross-sectional view of the first joint and the second joint when they are engaged in the first embodiment;

FIG6 is a cross-sectional view of the first joint and the second joint when they are axially separated in the first embodiment;

FIG7 is a partial exploded view of the linear actuator in Embodiment 1;

FIG8 is a perspective view of the first joint in Example 1;

FIG. 9 is a three-dimensional diagram of the shifter in the second embodiment.

Reference numerals:

100, motor; 110, output shaft;

200, transmission assembly;

300, screw;

400, tubular telescopic member; 410, transmission nut; 420, tubular member;

500, front pull assembly; 510, front pull head; 520, hand-twist release device; 521, first connector; 522, second connector; 523, brake torsion spring; 524, operating handle; 5241, snap ring; 525, anti-wear nut;

600, clutch assembly; 610, first joint; 611, shaft connection hole; 6111, small diameter hole; 6112, large diameter hole; 6113, step surface; 640, meshing teeth; 620, second joint; 621, connecting shaft; 6211, mounting hole; 622, fastener; 6221, locking screw; 6222, locking nut; 623, thrust bearing; 630, elastic component;

700, housing; 710, outer tube;

810, base; 820, boom.

DETAILED DESCRIPTION

The technical solutions of the embodiments of the present invention are explained and described below in conjunction with the drawings of the embodiments of the present invention, but the following embodiments are only preferred embodiments of the present invention, not all. Based on the embodiments in the implementation mode, other embodiments obtained by those skilled in the art without creative work are all within the protection scope of the present invention.

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, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

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. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more, unless otherwise clearly specified.

In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" 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.

In the present invention, 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.

Embodiment 1:

The linear actuator, as shown in Figures 1 to 8, includes a housing 700, and also includes a motor 100, a transmission assembly 200, a screw rod 300, a tubular telescopic component 400, a front pull assembly 500 and a clutch assembly 600 arranged in the housing 700. An output shaft 110 is provided on the motor 100, and the transmission assembly 200 is connected between the output shaft 110 of the motor 100 and the screw rod 300. The motor 100 drives the screw rod 300 to rotate through the transmission assembly 200. Preferably, the transmission assembly 200 is a transmission wheel, and the outer peripheral side of the transmission wheel is engaged with the output shaft 110 of the motor 100. The end of the screw rod 300 is passed through and fixed on the transmission wheel. 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 using the linear actuator, because the outer shell of one end of the linear actuator is fixed, the tubular telescopic component 400 at the other end is connected to a heavy object such as a hospital bed, a desktop platform, etc. through the front pull assembly 500, so that 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 motion along the central axis of the screw rod 300, that is, the tubular telescopic component 400 moves along the axial direction of the screw rod 300 to extend or retract the outer tube 710. The front pull assembly 500 is connected to the end of the outer tube 710 away from the transmission assembly 200 through the clutch assembly 600. The tubular telescopic component 400 drives the front pull assembly 500 to move by telescoping, thereby driving the object connected to the front pull assembly 500 (such as a hospital bed, a desktop platform, etc.) to move.

The clutch assembly 600 includes a first joint 610, a second joint 620 and an elastic component 630. The first joint 610 is connected to the tubular telescopic component 400, and the second joint 620 is connected to the front pull assembly 500. The first joint 610 and the second joint 620 can be relatively displaced in the axial direction so that the opposite ends of the first joint 610 and the second joint 620 are separated or meshed in the axial direction. The elastic component 630 pushes the ends of the first joint 610 and the second joint 620 to keep meshing under the action of elastic force. The meshed first joint 610 and the second joint 620 can keep relatively fixed in the circumferential direction. The motor 100 drives the screw rod 300 to rotate through the transmission assembly 200, and the tubular telescopic component 400 moves along the central axis of the screw rod 300 to perform linear telescopic motion. The meshed first joint 610 and the second joint 620 drive the front pull assembly 500 to move together with the tubular telescopic component 400 in the axial direction. During this process, the tubular telescopic component 400 does not rotate.

The present invention provides a clutch assembly 600 between the front pull assembly 500 and the tubular telescopic component 400, and configures the clutch assembly 600 to be a structure in which the first joint 610, the second joint 620, and the elastic component 630 cooperate with each other, so that during the retraction of the tubular telescopic component 400, if an object connected to the end of the tubular telescopic component 400 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 front pull assembly 500 will be subjected to an axial tensile load, so that the second joint 620 and the first joint 610 are axially displaced. The first joint 610 is separated from the second joint 620 and is no longer relatively fixed in the circumferential direction, that is, the second joint 620 and the front pulling assembly 500 no longer limit the tubular telescopic component 400 in the circumferential direction. At this time, the rotating screw 300 can drive the tubular telescopic component 400 and the first joint 610 connected to the tubular telescopic component 400 to rotate idly, so as to prevent the tubular telescopic component 400 from continuing to drive the object connected to the front pulling assembly 500 to retract and cause squeezing of obstacles (such as people or objects), thereby preventing the obstacles from being damaged and also preventing the obstacles from damaging the linear actuator. After encountering an obstacle, the user can control the motor 100 to reverse through a hand controller or other structure to drive the screw rod 300 to rotate in the opposite direction. While the tubular telescopic component 400 rotates driven by the screw rod 300, due to the friction between the two and the pulling of the elastic component 630 on the first joint 610, the tubular telescopic component 400 simultaneously moves slightly toward the second joint 620, so that the first joint 610 and the second joint 620 are re-engaged, so that the second joint 620 re-limits the tubular telescopic component 400 in the circumferential direction through the first joint 610, and then the tubular telescopic component 400 drives the front pulling assembly 500 to move away from the obstacle through the first joint 610 and the second joint 620, so that the user can remove the obstacle. Of course, the user can also directly remove the obstacle. At the moment of removing the obstacle, under the elastic force of the elastic component 630, the second joint 620 moves toward the first joint 610 to resume engagement with the first joint 610. The user can control the tubular telescopic component 400 of the linear actuator to continue to retract, which is convenient and simple to operate. Because there is an engagement structure between the first joint 610 and the second joint 620, the engagement structure allows the first joint 610 and the second joint 620 to be separated by a small distance in the axial direction to achieve disengagement. 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 second joint 620 to resume engagement with the first joint 610 is small, that is, the distance for objects such as a hospital bed or a desktop platform connected to the front pull assembly 500 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.

The friction between the tubular telescopic component 400 and the screw rod 300 in this embodiment is controllable. When the user presses the hand control to control the retraction of the tubular telescopic component 400 and encounters an obstacle, if the user stops pressing in time or the linear actuator has safety protection measures such as power-off protection, the first joint 610 and the second joint 620 are in a position where they are just disengaged; even if the user fails to stop pressing in time, the displacement of the tubular telescopic component 400 relative to the screw rod 300 when it rotates freely is also very small, and the distance for the first joint 610 and the second joint 620 to resume engagement is slightly greater than the axial engagement length, so that when the linear actuator is used as a lifting structure, the distance for resuming engagement is still maintained within a small controllable range, that is, the distance for the object to move downward quickly is maintained within a small controllable range, which can avoid damage to the object connected to the front pulling assembly 500 and ensure the safe use of the linear actuator.

As shown in FIGS. 5 to 7 , the second joint 620 has a connecting shaft 621, and the first joint 610 has a shaft connection hole 611, the shaft connection hole 611 is used for the connecting shaft 621 to pass through and connect, a first axial stop is provided in the shaft connection hole 611, and a second axial stop is provided on the connecting shaft 621, and an elastic component 630 is installed on the connecting shaft 621, and the two ends of the elastic component 630 abut against the first axial stop and the second axial stop respectively, so that the elastic component 630 is pre-tightened between the first axial stop and the second axial stop. The cooperation between the connecting shaft 621 and the shaft connection hole 611 can guide the first joint 610 and the second joint 620, so that the two can only move relative to each other along the axial direction, and the operation is stable, and at the same time, it is convenient to install the elastic component 630, and the elastic component 630 is hidden in the shaft connection hole 611 of the first joint 610.

As shown in Figure 8, the axial connection hole 611 in this embodiment is a two-section structure, including a small diameter hole 6111 and a large diameter hole 6112. The connection between the small diameter hole 6111 and the large diameter hole 6112 forms a step surface 6113 of a first axial stop. The elastic component 630 is arranged in the large diameter hole 6112. One end of the elastic component 630 abuts against the connecting shaft 621, and the other end abuts against the step surface 6113. By setting the shaft connection hole 611 to a structure in which a small diameter hole 6111 and a large diameter hole 6112 cooperate, the shaft connection hole 611 can not only guide the connecting shaft 621 in the axial direction and limit it in the radial direction through the small diameter hole 6111, thereby ensuring the stable movement of the connecting shaft 621 in the shaft connection hole 611, but also accommodate the elastic component 630 through the large diameter hole 6112. At the same time, the step surface 6113 formed between the small diameter hole 6111 and the large diameter hole 6112 can also serve as a stop structure for the end of the elastic component 630, thereby reducing the difficulty of processing and manufacturing the first joint 610.

The second axial stop includes a fastener 622 and a thrust bearing 623. The thrust bearing 623 is arranged at the end of the connecting shaft 621 and fixed on the connecting shaft 621 through the fastener 622. One end of the elastic component 630 abuts against the thrust bearing 623, and the other end abuts against the step surface 6113 to achieve the limitation of the elastic component 630. As shown in FIG6 , when the first joint 610 and the second joint 620 move relative to each other in the axial direction to separate, the thrust bearing 623 of the second axial stop and the step surface 6113 of the first axial stop jointly squeeze the elastic component 630 to gradually compress the elastic component 630, thereby increasing the friction between the two ends of the elastic component 630 and the first axial stop and the second axial stop. Because the elastic component 630 is against the end surface of the rotatable thrust bearing 623 on the connecting shaft 621, the thrust bearing 623 can ensure that the connecting shaft 621 will not be hindered from rotating the elastic component 630 due to the large friction between the second axial stop and the elastic component 630. That is, the first joint 610 and the second joint 6 When the first joint 610 is in an axially separated state, the tubular telescopic component 400 rotates to drive the first joint 610 to rotate. The first joint 610 drives the elastic component 630 to rotate together through the larger friction between the step surface 6113 and the elastic component 630. The half circle of the thrust bearing 623 close to the elastic component 630 rotates together with the elastic component 630, avoiding the friction between the second axial stopper at the end of the connecting shaft 621 and the elastic component 630 to hinder the rotation of the first joint 610, thereby ensuring that the elastic component 630 can rotate smoothly relative to the connecting shaft 621, thereby avoiding the situation where the tubular telescopic component 400 is difficult to rotate due to the large friction between the second axial stopper and the elastic component 630.

The fastener 622 in this embodiment is threadedly connected to the connecting shaft 621. The distance between the thrust bearing 623 and the step surface 6113 is adjusted by adjusting the axial position of the thrust bearing 623 on the connecting shaft 621, and then the preload force of the elastic component 630 is adjusted to ensure the pushing effect of the elastic component 630 on the second joint 620. Preferably, the fastener 622 includes a matching locking screw 6221 and a locking nut 6222, the thrust bearing 623 is sleeved on the locking screw 6221 and clamped between the head of the locking screw 6221 and the locking nut 6222, the outer peripheral side of the locking nut 6222 is provided with an external thread, the end of the connecting shaft 621 is provided with a mounting hole 6211 with an internal thread, the locking nut 6222 is arranged in the mounting hole 6211, and the locking nut 6222 is threadedly connected to the mounting hole 6211. By rotating the locking nut 6222, the fastener 622 can be moved along the axial direction of the mounting hole 6211, thereby adjusting the axial position of the thrust bearing 623 on the connecting shaft 621. The structure is simple and reliable, and it is easy to operate.

In this embodiment, the elastic component 630 can be one of a disc spring, a coil spring, and a rubber spring. The disc spring has the advantages of high rigidity and strong buffering and vibration absorption ability. It can withstand large loads with a small deformation amount and is suitable for occasions with small axial space requirements. As the elastic component 630, it occupies a small space; the coil spring has a high elastic coefficient, a compact structure and a small mass, and its rigidity is stable. As the elastic component 630, its service life can be extended. The rubber spring has the advantages of high internal resistance, simple structure, strong impact resistance and spring reset ability. When used as the elastic component 630, it has a good reset effect of pushing the second joint 620. Of course, the elastic component 630 can also be a combination of any two or three of the disc spring, coil spring, and rubber spring.

In this embodiment, ratchet engagement or spline engagement can be used between the first joint 610 and the second joint 620. The ratchet engagement makes the installation between the first joint 610 and the second joint 620 more convenient and simple, and the spline engagement can ensure good transmission effect and strong load-bearing capacity between the first joint 610 and the second joint 620.

As shown in FIG2 , the front pull assembly 500 in this embodiment includes a front pull head 510 and a hand-twist release device 520. The front pull head 510 is used to connect to objects such as a hospital bed and a desktop platform. The hand-twist release device 520 is used for the user to manually control the movement of objects such as a hospital bed and a desktop platform connected to the front pull head 510 when the power is suddenly cut off. As shown in FIG5 and FIG6 , the hand-twist release device 520 includes a first connector 521, a second connector 522, a brake torsion spring 523 and an operating handle 524. The first connector 521 is fixedly connected to the front pull head 510 to be linked to the front pull head 510 in the axial and circumferential directions. The second connector 522 is fixedly connected to the end of the second joint 620 to be connected to the tubular telescopic component 400 through the second joint 620. The second connector 522 is nested in the first connector 521 so that the first connector 521 and the second connector 522 are coaxially arranged, and the first connector 521 and the second connector 522 can rotate around the center. The shafts rotate relative to each other, the brake torsion spring 523 is pressed against the inner surface of the first connecting body 521, the operating handle 524 is a sleeve structure, the operating handle 524 is sleeved outside the first connecting body 521, one end of the brake torsion spring 523 is plugged into the second connecting body 522, so that one end of the brake torsion spring 523 is fixed on the second connecting body 522, and the other end of the brake torsion spring 523 is plugged into the operating handle 524, so that the other end of the brake torsion spring 523 is fixed on the operating handle 524, and the operating handle 524 is provided with a retaining ring 5241 that restricts the first connecting body 521, the second connecting body 522 and the brake torsion spring 523 inside. In order to reduce the wear between the first connecting body 521 and the second connecting body 522, in this embodiment, an anti-wear nut 525 can be provided between the end faces of the first connecting body 521 and the second connecting body 522.

The operating handle 524 is used to rotate and drive the brake torsion spring 523 to retract, so as to release the first connecting body 521 and hold the second connecting body 522 tightly, thereby driving the second connecting body 522 to rotate. Preferably, the first connecting body 521 and the front pull head 510 are an integrated structure, and the second connecting body 522 and the second joint 620 are an integrated structure, so as to reduce the number of parts, reduce the difficulty of assembly, and improve the assembly efficiency.

When the linear actuator is working normally, the lead screw 300 drives the tubular telescopic component 400 threadedly connected to it to extend and retract by rotating. The tubular telescopic component 400 drives the second connecting body 522 to move through the meshing first joint 610 and the second joint 620, thereby driving the first connecting body 521 and the front pulling head 510 connected to objects such as a hospital bed and a desktop platform to move. At this time, the braking torsion spring 523 is in abutment against the inner surface of the first connecting body 521 and does not contact the outer surface of the second connecting body 522.

When the linear actuator is suddenly powered off, the screw rod 300 is clamped by the internal self-locking structure to prevent the tubular telescopic component 400 from retracting. The user can rotate the operating handle 524 so that the braking torsion spring 523 clamps the second connecting body 522 and no longer abuts against the inner wall of the first connecting body 521. At this time, the operating handle 524 can drive the second connecting body 522 to rotate relative to the first connecting body 521, and the second connecting body 522 drives the second joint 620 to rotate, and the second joint 620 drives the first joint 610 to rotate, thereby driving the tubular telescopic component 400 to rotate relative to the screw rod 300, so that the tubular telescopic component 400 moves in the direction of retraction along the central axis of the screw rod 300, and the tubular telescopic component 400 pulls the clutch assembly 600, the front pulling assembly 500 and the object connected to the front pulling assembly 500 to move together to achieve retraction. When the linear actuator is used as a lifting structure to control the lifting of objects such as hospital beds and desktop platforms, the user can turn the operating handle 524 of the hand-rotated release device 520 by himself to lower the hospital beds, desktop platforms and other objects that have risen or fallen into the air, thereby improving the user experience.

In this embodiment, as shown in FIG. 7 , meshing teeth 640 are respectively provided on the first joint 610 and the second joint 620, and the thickness of the meshing teeth 640 of the first joint 610 and the second joint 620 is less than or equal to 15 mm, that is, the axial meshing length of the first joint 610 and the second joint 620 is not greater than 15 mm. By controlling the axial meshing length of the first joint 610 and the second joint 620, when the tubular telescopic component 400 retracts and encounters an obstacle, if the user directly removes the obstacle, the second joint 620 quickly moves toward the first joint 610 to restore the meshing distance with the first joint 610 and maintains at about 15 mm. 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 small and controllable, 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, thereby ensuring the safety of the linear actuator and avoiding injury to the operator or user. Preferably, the axial engagement length of the first joint 610 and the second joint 620 is 10 mm. In this embodiment, preferably, the end surface of the meshing tooth 640 is set to a ramp structure, and when the first joint 610 and the second joint 620 are relatively displaced to restore the meshing, the ramp structure can assist the meshing teeth 640 on the first joint 610 and the second joint 620 to mesh smoothly, so that the meshing of the two is smoother.

Preferably, the tubular telescopic component 400 includes a transmission nut 410 and a tubular component 420, the tubular component 420 is threadedly connected to the first joint 610, the transmission nut 410 is sleeved on the outer peripheral side of the screw rod 300 and is threadedly connected to the screw rod 300, the transmission nut 410 is arranged at one end of the tubular component 420, the transmission nut 410 can be fixed to the tubular component 420 by a locking structure, and can also be integrally arranged with the tubular component 420 to achieve the inseparable relationship between the two, so as to avoid the transmission nut 410 and the tubular component 420 from being disengaged when the linear brake encounters an obstacle during retraction, and to avoid damage to the tubular telescopic component 400 and resulting in failure to transmit.

Embodiment 2:

The shifter, as shown in FIG9 , includes a base 810 and an arm 820, wherein the arm 820 is rotatably connected to the base 810, and also includes the linear actuator of the first embodiment, wherein a housing 700 at one end of the linear actuator is hinged to the base 810, and a tubular telescopic component 400 of the linear actuator is hinged to the arm 820, so that the arm 820 is driven to rise and fall through the telescopic movement of the tubular telescopic component 400 of the linear actuator.

The above is only a preferred embodiment of the present invention, and 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 (12)

1. A linear actuator, comprising:

a motor;

A transmission assembly;

the screw rod is driven to rotate by motor power transmitted by the transmission assembly;

a tubular expansion member driven by the rotational movement of the screw rod to perform linear expansion movement;

The front pulling assembly is arranged at the end part of the tubular telescopic component through a clutch assembly;

The clutch assembly comprises a first connector connected with the tubular telescopic component, a second connector connected with the front pulling assembly and an elastic component for providing engagement thrust for the first connector and the second connector, wherein the first connector and the second connector are kept circumferentially fixed relatively and can axially move relatively when engaged, so that the front pulling assembly can drive the second connector and the first connector to axially separate when being subjected to axial tensile load, and the tubular telescopic component can independently rotate in the axially separated state of the first connector and the second connector.

2. The linear actuator of claim 1, wherein: the second joint is provided with a connecting shaft, the first joint is provided with a shaft connecting hole, the shaft connecting hole is used for the connecting shaft to penetrate through, a first axial stop is arranged in the shaft connecting hole, a second axial stop is arranged on the connecting shaft, and the elastic component is arranged on the connecting shaft and is pre-tightened between the first axial stop and the second axial stop.

3. The linear actuator of claim 2, wherein: the shaft connecting hole comprises a small-diameter hole, a large-diameter hole and a step surface for connecting the small-diameter hole and the large-diameter hole, the small-diameter hole guides the axial displacement of the connecting shaft, and the elastic part is accommodated in the large-diameter hole and abuts against the step surface for forming the first axial stop.

4. The linear actuator of claim 2, wherein: the second axial stop comprises a fastener and a thrust bearing, the thrust bearing is mounted on the connecting shaft through the fastener, the elastic component abuts against the thrust bearing, and the first joint and the second joint are kept independently rotated through the thrust bearing in an axial separation state.

5. The linear actuator of claim 4, wherein: the fastener is in threaded connection with the connecting shaft and is used for adjusting the pretightening force of the elastic component.

6. The linear actuator of claim 2, wherein: the elastic component is one or a combination of a belleville spring, a spiral spring and a rubber spring.

7. The linear actuator of claim 1, wherein: the first joint and the second joint are engaged by ratchet or spline.

8. The linear actuator of claim 1, wherein: the front pull assembly comprises a front pull head and a hand rotation release device, and the hand rotation release device comprises:

a first connecting body connected with the front slider;

A second connector connecting the tubular telescoping members, the second connector being nested in the first connector and both forming a rotatable axial location;

The brake torsion spring is tightly pressed on the inner surface of the first connector, and one end of the brake torsion spring is fixed on the second connector;

The operation handle is assembled outside the first connecting body in a structure of a sleeve, and is used for driving the braking torsion spring to retract and release the first connecting body and driving the second connecting body to rotate.

9. The linear actuator of claim 8, wherein: the second connector and the second joint are constructed as a unitary structure.

10. The linear actuator according to any one of claims 1 to 9, wherein: the axial engagement length of the first joint and the second joint is less than or equal to 15mm.

11. The linear actuator according to any one of claims 1 to 9, wherein: the tubular telescopic component comprises a transmission nut and a tubular component, wherein the transmission nut is in threaded fit with the screw rod, and the tubular component and the transmission nut are connected inseparably.

12. Shifter, including the base with rotate connect in the davit on the base, its characterized in that: the shifter further comprises the linear actuator of any one of claims 1 to 11, wherein one end of the linear actuator is hinged to the base, the tubular telescopic part is hinged to the suspension arm, and telescopic movement of the tubular telescopic part drives the suspension arm to lift.