Motor self-locking device of a linear actuator and linear actuator

Abstract

The application discloses a motor self-locking device of a linear actuator, and belongs to the field of linear actuating devices. The motor self-locking device is sleeved on a motor output shaft and comprises an outer ring member and an inner friction sleeve. The inner friction sleeve is fixedly and synchronously rotated relative to the motor output shaft. The outer ring member is sleeved outside the inner friction sleeve. The outer wall of the inner friction sleeve is in interference fit with the inner wall of the outer ring member. At least one scaling gap for adjusting the outer diameter of the inner friction sleeve is arranged on the outer circumferential side wall of the inner friction sleeve. The extension direction of the scaling gap is obliquely intersected with the circumferential movement direction of the inner friction sleeve. The application further discloses a linear actuator adopting the motor self-locking device. The motor self-locking device has the advantage that the self-locking capacity of the linear actuator can be increased.

Description

[Technical Field]

[0001] This invention relates to a motor self-locking device for a linear actuator and a linear actuator, belonging to the field of linear actuator equipment. [Background Technology]

[0002] Linear actuators are currently widely used in various fields, including electric height-adjustable desks, electric beds, electric sofas, etc. The structure of such linear actuators typically includes a drive motor, a rotating lead screw, and a transmission nut. The drive motor drives the rotating lead screw to rotate, and when the rotating lead screw rotates, it drives the transmission nut to move axially. The transmission nut can be connected to the driven object, thereby achieving the driving purpose.

[0003] However, for this type of linear actuator, self-locking is an essential function. Examples include electric lifting desks and electric beds. When the motor is not running, the linear actuator needs to have self-locking capability to prevent the desk from automatically descending or the bed from automatically returning to its original position. Currently, most linear actuators rely on brake torsion springs for self-locking. The reverse rotation of the lead screw drives the brake torsion spring to clamp and generate braking force. However, the self-locking force of this current structure is relatively insufficient. [Summary of the Invention]

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a motor self-locking device and a linear actuator for a linear actuator, which can increase the self-locking capability of the linear actuator.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A motor self-locking device for a linear actuator is mounted on a motor output shaft. The device includes an outer ring component and an inner friction sleeve. The inner friction sleeve is fixed relative to the motor output shaft and rotates synchronously. The outer ring component is mounted outside the inner friction sleeve. The outer wall of the inner friction sleeve is interference-fitted with the inner wall of the outer ring component. At least one scaling notch is provided on the outer peripheral sidewall of the inner friction sleeve for adjusting the outer diameter of the inner friction sleeve. The extending direction of the scaling notch is obliquely intersecting the circumferential movement direction of the inner friction sleeve.

[0007] The beneficial effects of using the present invention are as follows:

[0008] In this invention, the motor self-locking device is installed on the motor. This design does not require any changes to the internal structure of the original linear actuator. Only the self-locking device needs to be added to the motor, which reduces the cost of modification. Moreover, this installation structure is applicable to linear actuators of various specifications. Since all linear actuators use motors, this motor self-locking device can be applied to many linear actuators.

[0009] Secondly, the motor self-locking device in this invention uses a structure with a scaling notch on the inner friction sleeve to adjust the outer diameter of the inner friction sleeve. The outer wall of the inner friction sleeve is interference-fitted with the inner wall of the outer ring component, and the extension direction of the scaling notch is inclined to intersect the circumferential movement direction of the inner friction sleeve. This design means that when the inner friction sleeve moves circumferentially relative to the outer ring component, if the inner friction sleeve rotates along the extension direction of the scaling notch, the scaling notch will be enlarged to a certain extent under the action of circumferential friction force. After the scaling notch is enlarged, the outer diameter of the inner friction sleeve will increase. After the outer diameter of the inner friction sleeve increases, the friction force between the inner friction sleeve and the outer ring component will increase, thereby increasing the resistance. However, if the inner friction sleeve rotates in the opposite direction of the extension direction of the scaling notch, the scaling notch will remain basically unchanged or even become smaller, so that the outer diameter of the inner friction sleeve remains the same as the initial or becomes smaller. In this way, the resistance between the inner friction sleeve and the outer ring component will remain basically unchanged or even become smaller. This ensures that when the motor rotates in one direction, the self-locking device does not cause the self-locking force to increase, but when the motor rotates in the opposite direction, the self-locking device starts to work and the self-locking force increases.

[0010] Preferably, the motor output shaft is in a self-locking state when it reverses direction, and the extension direction of the scaling notch is opposite to and obliquely intersects the forward rotation direction of the motor output shaft.

[0011] Preferably, the inner friction sleeve is provided with a plurality of scaling notches at uniform intervals in the circumferential direction.

[0012] Preferably, the inner friction sleeve includes a friction ring and an inner bushing, wherein the inner bushing is fixedly fitted to the motor output shaft, and the friction ring is fixedly fitted to the inner bushing.

[0013] Preferably, the outer ring of the inner bushing is provided with a plurality of positioning keys, and the friction collar is provided with a keyway that mates with the positioning keys.

[0014] Preferably, the friction collar is an elastomer, and the inner bushing is a hard body.

[0015] Preferably, the scaling notch is an arc-shaped groove or a wedge-shaped groove.

[0016] Preferably, the outer ring component is a rigid body, and the inner friction sleeve is an elastic body.

[0017] Preferably, the motor includes a motor housing, a motor output shaft extending out of the motor housing, and the outer ring member mounted at the end of the motor housing.

[0018] In addition, the present invention also discloses a linear actuator, including an inner tube, an outer tube, a rotating lead screw, a transmission nut, and a motor. The motor drives the rotating lead screw to rotate, and when the rotating lead screw rotates, it drives the transmission nut to move axially. The movement of the transmission nut causes the inner tube and the outer tube to expand and contract relative to each other. The motor is equipped with a motor self-locking device as described in any of the above embodiments.

[0019] These features and advantages of the present invention will be disclosed in detail in the following specific embodiments and accompanying drawings. [Attached Image Description]

[0020] The invention will be further described below with reference to the accompanying drawings:

[0021] Figure 1 This is a schematic diagram of the linear actuator in Embodiment 1 of the present invention;

[0022] Figure 2 This is an exploded view of the linear actuator in Embodiment 1 of the present invention;

[0023] Figure 3 This is a schematic diagram of the internal structure of the self-locking device after assembly in Embodiment 1 of the present invention;

[0024] Figure 4 This is a top view schematic diagram of the self-locking device in Embodiment 1 of the present invention;

[0025] Figure 5 This is a top view of the self-locking device in Embodiment 2 of the present invention.

Detailed Implementation Methods

[0026] The technical solutions of the embodiments of the present invention will be explained and described below with reference to the accompanying drawings. However, the following embodiments are only preferred embodiments of the present invention and not all of them. Other embodiments obtained by those skilled in the art based on the embodiments in the implementation methods without creative effort are all within the protection scope of the present invention.

[0027] In the following description, terms such as “inner,” “outer,” “upper,” “lower,” “left,” and “right” are used to indicate orientation or positional relationships only for the convenience of describing embodiments and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0028] Example 1

[0029] like Figures 1 to 4 The diagram illustrates the application of the motor self-locking device 100 on a linear actuator. There are various types of linear actuators, such as lifting columns and electric push rods. In this embodiment, the self-locking device is specifically applied to an electric push rod.

[0030] In this embodiment, the motor self-locking device 100 is specifically mounted on the motor output shaft 10, including an outer ring component 3 and an inner friction sleeve 2. The inner friction sleeve 2 is fixed relative to the motor output shaft 10 and rotates synchronously. The outer ring component 3 is mounted on the outer side of the inner friction sleeve 2. The outer wall of the inner friction sleeve 2 is press-fitted with the inner wall of the outer ring component 3. At least one scaling notch 201 for adjusting the outer diameter of the inner friction sleeve 2 is provided on the outer peripheral side wall of the inner friction sleeve 2. The extending direction of the scaling notch 201 is inclined to intersect the circumferential movement direction of the inner friction sleeve 2.

[0031] It should be noted that the extension direction of the scaling notch 201 mentioned in this article refers to one orientation of the scaling notch 201, which can be basically represented by the direction of the line connecting the inner and outer ends of the scaling notch 201. Figure 4 The direction F in the middle, and the direction of the connecting line intersects the circumferential movement direction of the inner friction sleeve 2 at an angle, can be understood as the direction F being inclined to the tangential direction T at the outer end of the scaling notch 201. Thus, when the scaling notch 201 is scaled, it will affect the outer diameter of the inner friction sleeve 2. When the scaling notch 201 is enlarged, the outer diameter of the inner friction sleeve 2 will increase, and when the scaling notch 201 is compressed, the outer diameter of the inner friction sleeve 2 will decrease.

[0032] Since the motor self-locking device 100 in this embodiment is installed on the motor 1, this design does not require any modification to the internal structure of the original linear actuator. Only the self-locking device needs to be added to the motor 1, which reduces the cost of modification. Moreover, this installation structure is applicable to linear actuators of various specifications. Since all linear actuators use motors, this motor self-locking device 100 can be applied to many linear actuators.

[0033] Secondly, the motor self-locking device 100 in this embodiment adopts a structure in which a scaling notch 201 is provided on the inner friction sleeve 2 to adjust the outer diameter of the inner friction sleeve 2. This design means that when the inner friction sleeve 2 moves circumferentially relative to the outer ring component 3, if it rotates along the extension direction of the scaling notch 201, the scaling notch 201 will be enlarged to a certain extent under the action of circumferential friction force. After the scaling notch 201 is enlarged, the outer diameter of the inner friction sleeve 2 will be increased. After the outer diameter of the inner friction sleeve 2 increases, the friction between it and the outer ring component 3 will increase, thereby increasing the resistance. However, if the inner friction sleeve 2 rotates in the opposite direction of the extension direction of the scaling notch 201, the scaling notch 201 will remain basically unchanged or even become smaller, so that the outer diameter of the inner friction sleeve 2 remains the same as the initial or becomes smaller. In this way, the resistance between the inner friction sleeve 2 and the outer ring component 3 will remain basically unchanged or even become smaller. This ensures that when motor 1 rotates in one direction, the motor self-locking device 100 does not cause the self-locking force to increase, but when motor 1 rotates in the opposite direction, the motor self-locking device 100 starts to work and the self-locking force increases.

[0034] It should be noted that the main function of this motor self-locking device is to prevent the linear actuator from returning to its original position when the motor stops working. However, if the motor 1 actively reverses, the reversing torque is sufficient to overcome the self-locking force. Therefore, when the motor 1 actively reverses, the motor self-locking device 100 is insufficient to prevent the entire linear actuator from returning to its original position. However, when the motor stops working and the linear actuator is driven by an external force, causing the motor output shaft 10 to have a tendency to reverse, the motor self-locking device 100 of this embodiment will produce a significant self-locking effect.

[0035] In terms of specific structure, you can refer to Figure 4 As shown in the figure, the clockwise direction is the reverse direction of motor 1. In this embodiment, the reverse direction of motor output shaft 10 is in a self-locking state, that is, self-locking is triggered when motor output shaft 10 is subjected to a reverse trend. In this embodiment, the shape of the scaling notch 201 is an arc-shaped slot. The extension direction of the scaling notch 201, that is, direction F in the figure, is basically the line connecting the inner endpoint a and the outer midpoint b of the scaling notch 201. This direction F is opposite to the forward rotation direction of motor output shaft 10 and intersects it at an angle.

[0036] When the motor output shaft 10 rotates counterclockwise, it drives the inner friction sleeve 2 to rotate counterclockwise as a whole. At this time, the scaling notch 201 will not increase, so the outer diameter of the inner friction sleeve 2 will not increase. However, when the motor output shaft 10 rotates clockwise, the rotation direction of the inner friction sleeve 2 and the extension direction of the scaling notch 201 tend to be the same, which causes the scaling notch 201 to increase, thereby increasing the outer diameter of the inner friction sleeve 2 and thus increasing the self-locking force.

[0037] Regarding the material selection, the outer ring component 3 is preferably a rigid material, while the inner friction sleeve 2 is an elastic material. This combination of an elastic and a rigid material allows for a larger interference fit between the inner friction sleeve 2 and the outer ring component 3 as the outer diameter of the inner friction sleeve 2 increases, thereby increasing the frictional resistance between them. However, it should be noted that the term "elastic material" for the inner friction sleeve 2 in this text does not mean that the entire inner friction sleeve 2 is elastic; it can simply be an elastic material in the portion in contact with the outer ring component 3.

[0038] In order to make the friction between the inner friction sleeve 2 and the outer ring component 3 more uniform and stable, the inner friction sleeve 2 in this embodiment is provided with a plurality of scaling notches 201 evenly spaced in the circumference. Such a plurality of scaling notches 201 can have a multi-point expansion effect on the outer diameter of the inner friction sleeve 2, thereby making the friction resistance generated evenly at multiple positions between the inner friction sleeve 2 and the outer ring component 3.

[0039] Regarding the structure of the inner friction sleeve 2, in this embodiment, the inner friction sleeve 2 includes two components: a friction ring 21 and an inner bushing 22. The inner bushing 22 is fixedly fitted to the motor output shaft 10, and the friction ring 21 is fixedly fitted to the inner bushing 22. The purpose of this design is that, since the inner friction sleeve 2 is preferably an elastomer, while the motor output shaft 10 is usually a hard metal shaft, it is difficult to ensure that the inner friction sleeve 2 and the motor output shaft 10 do not rotate relative to each other when the inner friction sleeve 2 is directly fitted onto the motor output shaft 10. By setting the inner friction sleeve 2 as a friction ring 21 and an inner bushing 22, the inner bushing 22 can be made of a hard material and then directly fitted onto the motor output shaft 10 with an interference fit. The friction ring 21 is made of an elastomer. In this way, it can ensure the synchronous rotation of the friction ring 21 and the motor output shaft 10, and also ensure that the friction ring 21 has good elastic deformation capability.

[0040] Regarding the fixed connection between the inner bushing 22 and the friction ring 21, in this embodiment, it is preferable to have multiple positioning keys on the outer ring of the inner bushing 22, so the inner bushing 22 is similar to a spline sleeve. The friction ring 21 is provided with a keyway that cooperates with the positioning keys, so as to ensure that there is no relative rotation between the inner bushing 22 and the friction ring 21.

[0041] In addition, the motor self-locking device 100 in this embodiment also includes a cover 4, which is fixedly installed on the top of the outer ring component 3, thereby enclosing the inner friction sleeve 2 inside the outer ring component 3 to provide protection.

[0042] In terms of specific assembly, in this embodiment, the motor includes a motor housing, the motor output shaft 10 extends out of the end of the motor housing, the outer ring component 3 is installed at the end of the motor housing, that is, the outer ring component 3 is stationary, and the cover 4 is directly installed at the end of the outer ring component 3.

[0043] Example 2

[0044] like Figure 5 As shown, the difference between this embodiment and embodiment one is that in this embodiment, the inner friction sleeve 2 is a single component, and multiple ribs 101 are provided on the outer peripheral wall of the motor output shaft 10, so that the inner friction sleeve 2 can be directly fitted onto the motor output shaft 10.

[0045] Furthermore, in this embodiment, the shape of the scaling notch 201 has been changed to a wedge-shaped notch. It should be noted that there are many ways to implement the shape of the scaling notch 201, such as a rectangular notch, etc. As long as the extension direction F of the scaling notch 201 is approximately inclined to the circumferential direction of the inner friction sleeve 2, it falls within the protection scope of this invention.

[0046] Example 3

[0047] As mentioned above, see also Figure 1 and Figure 2 As shown, the linear actuator in this embodiment is preferably an electric push rod. This embodiment includes an inner tube 51, an outer tube 52, a rotating lead screw 61, a transmission nut 62, and a motor 1. The motor 1 drives the rotating lead screw 61 to rotate. When the rotating lead screw 61 rotates, it drives the transmission nut 62 to move axially. The movement of the transmission nut 62 causes the inner tube 51 and the outer tube 52 to extend or retract relative to each other. The motor 1 is equipped with a motor self-locking device 100, as in Embodiment 1 or Embodiment 2 or an equivalent embodiment.

[0048] Other structures of electric linear actuators are not discussed in detail in this article because they are widely disclosed in existing technologies.

[0049] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that the present invention includes, but is not limited to, the contents described in the accompanying drawings and the specific embodiments above. Any modifications that do not depart from the functional and structural principles of the present invention will be included within the scope of the claims.

Claims

1. A motor self-locking device for a linear actuator, characterized in that, The motor self-locking device is mounted on the motor output shaft and includes an outer ring component and an inner friction sleeve. The inner friction sleeve is fixed relative to the motor output shaft and rotates synchronously. The outer ring component is mounted outside the inner friction sleeve. The outer wall of the inner friction sleeve is interference-fitted with the inner wall of the outer ring component. The outer peripheral sidewall of the inner friction sleeve is provided with at least one scaling notch for adjusting the outer diameter of the inner friction sleeve. The extension direction of the scaling notch is obliquely intersecting the circumferential movement direction of the inner friction sleeve. The motor output shaft is in a self-locking state when rotating in reverse. The extension direction of the scaling notch is opposite to the forward rotation direction of the motor output shaft and obliquely intersecting it.

2. The motor self-locking device as described in claim 1, characterized in that, The inner friction sleeve is provided with a plurality of scaling notches at uniform intervals in the circumferential direction.

3. The motor self-locking device as described in claim 1, characterized in that, The inner friction sleeve includes a friction ring and an inner bushing. The inner bushing is fixedly fitted to the motor output shaft, and the friction ring is fixedly fitted to the inner bushing.

4. The motor self-locking device as described in claim 3, characterized in that, The outer ring of the inner bushing is provided with multiple positioning keys, and the friction collar is provided with keyways that cooperate with the positioning keys.

5. The motor self-locking device as described in claim 4, characterized in that, The friction collar is an elastic body, and the inner bushing is a hard body.

6. The motor self-locking device as described in claim 1, characterized in that, The scaling notch is in the form of an arc-shaped groove or a wedge-shaped groove.

7. The motor self-locking device as described in claim 1, characterized in that, The outer ring component is a rigid body, and the inner friction sleeve is an elastic body.

8. The motor self-locking device as described in claim 7, characterized in that, The motor includes a motor housing, a motor output shaft extending from the end of the motor housing, and an outer ring member mounted on the end of the motor housing.

9. A linear actuator, comprising an inner tube, an outer tube, a rotating lead screw, a transmission nut, and a motor, wherein the motor drives the rotating lead screw to rotate, and the rotation of the rotating lead screw causes the transmission nut to move axially, and the movement of the transmission nut causes relative expansion and contraction of the inner tube and the outer tube, characterized in that, The motor is equipped with a motor self-locking device as described in any one of claims 1 to 8.

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