CN113700816A

CN113700816A - Linear actuator and adjustable device comprising such a linear actuator

Info

Publication number: CN113700816A
Application number: CN202010437920.5A
Authority: CN
Inventors: 安思格·孟格尔
Original assignee: Linak AS
Current assignee: Linak Shenzhen Actuator System Ltd; Linak AS
Priority date: 2020-05-21
Filing date: 2020-05-21
Publication date: 2021-11-26

Abstract

A linear actuator comprises: an upper casing; a mandrel arranged between a front mounting part and a rear mounting part, on which a worm wheel is fixed, and an external thread is formed on the outer surface of the mandrel; The gear mechanism of the meshed worm, the motor holder is connected to the upper housing; the inner thread of the mandrel nut is engaged with the outer thread; the inner tube attached between the mandrel nut and the front mount is spaced around the mandrel; around the The outer tube part provided with the inner tube part, the mandrel nut is matched with the linear guide track on the outer tube part; the rear mounting part is an integral part, which includes a cylindrical rear section and a front section with a plurality of cantilever parts, each cantilever part is an integral part. The free ends of the sections each have radially inwardly extending projections against which a bearing is retained in the cavity defined by the front and rear sections. It also relates to an adjustable device comprising the linear actuator. The bearing accommodating cavity of the present application is made of a single part, which ensures the cylindricity and concentricity of the accommodating cavity.

Description

Linear actuator and adjustable device comprising such a linear actuator

Technical Field

The present invention relates to a linear actuator and an adjustable device comprising such a linear actuator. The linear actuator of the invention is particularly suitable for use with furniture-type products for adjusting the height, length, width and/or inclination of the furniture-type product.

Background

Linear actuators have found widespread use in industry as well as in everyday life, for example in the adjustment of the length, width, height and/or inclination of a patient, in particular a patient lying in bed for a long period of illness, or a bed used by a patient undergoing or having undergone surgery. Of course, the scope of application of the linear actuator is not limited thereto, but it may also be applied in other furniture type products where height, length, width and/or inclination adjustment is required.

In the case of the application of a linear actuator to a bed or patient lifting device of the above-mentioned kind, it would pose a great risk to the patient on the bed or device in case of a malfunction of the linear actuator (for example a deviation or jamming of the movement of the spindle due to a deviation of the cylindricity or concentricity of the housing chamber of the rear mounting housing the bearing).

The usual types of actuators mainly comprise: a linear actuator outer tube; a mandrel provided with an external thread; a reversible motor; a transmission mechanism connected with the reversible motor; a spindle nut formed with an internal thread to be engaged with the external thread of the spindle, the spindle nut having a maximum diameter portion formed with a sliding portion on an outer circumference thereof to be engaged with the guide rail on the inner surface of the outer pipe of the actuator; an actuating member having one end connected to one end of the spindle nut; the other end of the actuating element is connected with the front mounting piece; a rear mounting member; the rear end of the spindle is mounted in the rear mounting by means of a bearing; the spindle is provided with a worm wheel and the transmission mechanism comprises a worm, the worm wheel is meshed with the worm, the power of the reversible motor is transmitted to the spindle through the transmission mechanism and the meshed worm wheel and worm, the spindle is pushed to rotate, the rotary drive of the spindle is converted into the front and back linear movement of the spindle nut through the threaded fit between the spindle and the spindle nut, and the actuating element is moved back and forth, so that the front mounting piece is pushed or pulled to move back and forth relative to the rear mounting piece.

There are various drawbacks to the existing linear actuator, for example, a linear driver is disclosed in CN1281882C, in which a main shaft is mounted in a rear mount (i.e., a rear mount) through a ball bearing at a rear end portion thereof. It is clear from this prior art that: wherein the rear mount is of a two-piece design with recessed portions formed in each half of the rear mount.

In the assembled condition, the two halves of the rear support are joined to each other to form a complete housing cavity, so that the ball bearings are accommodated in the housing cavity formed by the corresponding two recessed portions.

This structure clearly has the following drawbacks:

1) the two halves are independently machined in different machining processes, and machining precision and machining errors of the two halves are different, so that deviation exists between cylindricity and concentricity of two parts of the accommodating cavity of the cylinder formed by the two halves. In the case of a bearing installed in the housing, the bearing experiences different support loads and wear conditions due to deviations in cylindricity and concentricity of the two halves, thereby preventing the bearing from operating and wearing consistently. And there is a case where the bearing is not operated normally in a deflected manner in the accommodation chamber. After a certain period of operation, the bearing is deformed due to uneven wear to which the bearing is subjected, which can cause jamming and failure of the bearing in the housing cavity. This makes the linear actuator and the equipment using it impossible to work properly, which would pose a great risk to the patient on the bed or the apparatus.

2) In the case of the linear actuators of the prior art assembled, the two halves are bolted, welded or glued or otherwise fixed together, and after a long period of operation, there is a risk of the bearings of the spindle becoming misaligned or out of position due to the work load, resulting in loosening of the connecting bolts or separation of the joints between the two halves, and thus making the linear actuator or the entire apparatus unable to function properly. Thereby increasing the operational risk and the cost of component replacement.

Based on this, there is a need in industrial applications and daily life to form a single integral housing chamber from an integral single component, to improve the cylindricity and concentricity of the housing chamber, to reduce waste of processing materials, to save labor costs, and to extend the service life of the linear actuator.

Disclosure of Invention

It is an object of the present invention to provide a linear actuator which obviates the above-mentioned drawbacks and disadvantages of the prior art and which provides a rear mounting having a desired cylindricity and concentricity and which enables a smooth and safe operation of the linear actuator and the adjustable device on which it is mounted.

The present invention relates to a linear actuator, wherein the linear actuator comprises:

an upper housing;

a spindle disposed between the front mount and the rear mount, a worm gear fixedly mounted on the spindle, and an external thread formed on an outer surface of the spindle between the worm gear and the front mount;

a motor and a transmission mechanism including a worm engaged with the worm wheel, the motor being disposed in a motor holder, the motor holder being connected to the upper housing;

a spindle nut disposed on the spindle, the spindle nut having an internal thread that engages the external thread of the spindle;

an inner pipe member attached at one end to the spindle nut and at the other end to a front mounting member, the inner pipe member being disposed around the spindle in parallel with the spindle at a certain interval;

an outer pipe member disposed around the inner pipe member in parallel with the inner pipe member at a certain interval;

wherein the rear mounting member is a unitary member comprising a cylindrical rear section and a front section having a plurality of identical cantilevered portions extending parallel forwardly from the cylindrical rear section in the axial direction of the spindle, the free end of each cantilevered portion having a radially inwardly extending projection against which a bearing on the rear end of the spindle is retained in a chamber defined by the front and rear sections.

Preferably, the plurality of identical cantilever portions are formed at equal angular intervals on the circumference of the cylindrical rear section.

Preferably, the plurality of identical cantilever portions are made of a plastic material having a certain hardness.

Preferably, an auxiliary bearing is provided on a base portion of the worm wheel fixedly mounted on the spindle, the auxiliary bearing being pressed between the base portion of the worm wheel and the upper housing of the linear actuator.

Preferably, the number of said plurality of identical cantilever portions is more than 2.

Preferably, a cavity is formed between the rear portion of the spindle nut and the spindle, in which cavity a safety nut is provided in threaded engagement with the spindle, the safety nut being retained on the spindle by the rear portion of the spindle nut.

Preferably, a coupling member of a stepped structure is fixedly mounted on a rear end portion of the spindle, the bearing is mounted on a small diameter portion of the stepped structure, and a coil spring is mounted on a large diameter portion of the stepped structure.

Preferably, a stopper holding portion is provided between two adjacent ones of the plurality of identical cantilever portions, and a catch portion formed by the stopper holding portion and one of the two adjacent cantilever portions fixes one end of the wrap spring extending outward, and the other end of the wrap spring is fixed to the coupling member.

Preferably, the catch is formed by both a catch on the retaining portion of the brake and a corresponding catch on one of the two adjacent cantilevered portions.

Preferably, a gasket for slidably supporting the inner pipe is disposed between the stopper and the inner pipe, and the gasket is a polyoxymethylene gasket.

Preferably, the spindle nut cooperates with a linear guide track on the outer tubular member to allow forward and backward movement of the spindle nut.

Preferably, the front end of the mandrel is supported in the inner tube by a rigid stop.

The invention also relates to an adjustable device, characterised in that it comprises a linear actuator according to the preceding technical disclosure, the front and rear mounts of which are respectively mounted on corresponding mounts of the adjustable device, so as to adjust the size or inclination of the adjustable device.

Preferably, the adjustable device is a rehabilitation or surgical bed or furniture type device.

Compared with the prior art, the technical scheme of the invention can produce remarkable technical effects, such as: since the rear mounting member in the present application is machined from a single workpiece, the coaxiality and cylindricity of the bearing accommodating chamber formed in the rear mounting member are ensured; since the rear mounting member in the present application is machined from a single piece, the rigidity of the rear mounting member is increased to avoid the problem of separation between the joining parts that would be present if it were formed from multiple parts, thus eliminating the problems of bearing running, uneven wear of the bearings and the corresponding parts of the receiving chamber, and frequent replacement of parts. Still further, this configuration in the present application significantly reduces material and tooling costs.

The foregoing has outlined some of the teachings of the linear actuator and the adjustable device incorporating the same of the present application so that the detailed description that follows may be better understood. There are, of course, additional embodiments that will be described below and which will form the subject matter of the claims. In this regard, it is to be understood that the linear actuator is not limited in its application to the details of construction and the arrangement of components set forth in the following disclosure or illustrated in the drawings. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. Accordingly, the concepts upon which this disclosure is based may readily be utilized as a basis for designing other structures and systems for carrying out several purposes of linear actuators. It is therefore to be understood that the claims are intended to cover such equivalent constructions insofar as they do not depart from the spirit and scope of the present disclosure.

Drawings

Specific embodiments of the subject linear actuator are described with reference to the drawings, wherein like reference numerals refer to like parts throughout. The matters described in the present application and shown in the drawings are only for the purpose of enabling those skilled in the art to better understand and realize the technical solution disclosed in the present application, but the drawings and the description of the embodiments are only for illustrative purpose and the present application is not limited thereto. Note that in the embodiments described below, the same reference numerals are used in common between different drawings to denote the same portions or portions having the same functions, and a repetitive description thereof will be omitted. In some cases, similar reference numbers and letters are used to denote similar items, and thus, once an item is defined in one figure, it need not be discussed further in subsequent figures.

For convenience of understanding, the positions, sizes, ranges, and the like of the respective structures shown in the drawings and the like do not sometimes indicate actual positions, sizes, ranges, and the like. Therefore, the present disclosure is not limited to the positions, dimensions, ranges, and the like disclosed in the drawings and the like.

FIG. 1 is a perspective view of a linear actuator according to the present invention;

FIG. 2 is a cross-sectional view of the general structure of a linear actuator according to a specific embodiment of the present application, showing in detail the various components that the linear actuator contains and the mating and positional relationships between the components;

FIG. 3 schematically illustrates an exploded view of the bearing at the rear end of the spindle and the integral rear mount of FIG. 2 showing the major components between the worm gear and the rear mount;

FIG. 4 schematically shows a cross-sectional view taken along line A-A of FIG. 1;

figure 5 shows a view of the main components between the worm gear and the rear mount after mounting.

Detailed Description

Various exemplary embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. It should be noted that: the relative arrangement of the components and steps, the numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present disclosure unless specifically stated otherwise.

The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. That is, the devices and methods herein are shown by way of example to illustrate different embodiments of the devices and methods of the present disclosure. Those skilled in the art will understand, however, that they are merely illustrative of exemplary ways in which the disclosure may be practiced and not exhaustive.

Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate.

In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values.

Reference will now be made in detail to the preferred embodiments of the present application, with reference to the accompanying drawings, in which reference numerals have the following specific meanings, and in which fig. 1 is a cross-sectional view of the general structure of a linear actuator according to an embodiment of the present application:

1. -a rear mount;

1' — cylindrical part

1 "-cantilever portion;

1 "' -a boss;

2. -a gasket;

3. -a bearing;

4. -a coupling member;

4' — a large diameter portion;

4 "-small diameter portion;

5. a brake holding portion;

6. -a brake member;

6' -one end of the wrap spring;

6 "-the other end of the wrap spring;

7. -a worm gear;

8. -an auxiliary bearing;

9. -a holding member;

10. -a spindle nut;

11. -an outer tube;

12. -an inner tube;

13. -a stopper;

14. -a gasket;

15. -a front mount;

16. -an upper shell;

17. -an electric motor;

18. -a motor attachment bolt;

19. -a motor attachment bolt;

20. -a magnet;

21. -a clamp;

22. -a safety nut;

23. -a mandrel;

24. -a sleeve;

25. -a catch;

28. motor holder

For the purpose of convenience of description, the "right side" along the longitudinal axis of the spindle 23 in fig. 1 of the present invention is defined as a front side, and the side opposite thereto is defined as a rear side.

Referring to fig. 1 and 2, there is generally shown the linear actuator of the present invention and the positional mating relationship of the components therein in an assembled condition. The linear actuator of the present invention comprises: an upper housing 16; a front mounting member 15 having a mounting hole to which a fixing portion of a corresponding apparatus (e.g., a rehabilitation bed) is connected; a rear mounting member 1 having a mounting hole connected to another fixing portion of the equipment; a spindle 23 extending longitudinally between the front mounting member 15 and the rear mounting member 1, wherein a portion of the spindle 23 is formed with an external thread; a spindle nut 10 having an internal thread formed thereon, the internal thread being threadedly engaged with the external thread of the spindle; an inner tubular member 12 arranged substantially parallel and coaxially outside and at a distance from said spindle 23, which inner tubular member 12 functions as an actuating element, the rear end of which is connected to said spindle nut 10 and the front end of which is connected to a front mounting member 15; an outer pipe member 11 surrounding the inner pipe member 12 at a certain distance and coaxially arranged substantially in parallel with the inner pipe member 12, a track portion along which the spindle nut 10 moves forward and backward being formed on the outer pipe member 11; a motor 17, the motor 17 having an output shaft which is finally coupled to a worm which meshes with a worm wheel 7 fixed on a spindle 23 to drive the spindle. When the spindle 23 is driven in rotation, the rotational movement of the spindle 23 is translated into a back and forth linear movement of the spindle nut 10, which spindle nut 10 pushes or pulls the inner tube 12 and thereby the front mounting 15, thereby effecting an adjustment in the length, width or pitch of the equipment to which the linear actuator is connected.

As shown in fig. 2, the spindle nut 10 takes the form of two portions having different diameters, wherein a portion that engages with the rail portion of the outer pipe 11 is formed on the large diameter portion at the rear side shown in fig. 1 to facilitate the forward and backward movement of the spindle nut 10 along the rail portion of the outer pipe member 11. The rear end of the inner tube member 12 is fixedly mounted (e.g., by threaded mounting, adhesive or riveting) to the small diameter portion of the spindle nut 10, thereby being moved axially back and forth by the spindle nut 10.

The linear actuator is arranged with a holding element 9, which holding element 9 connects the rear mounting 1 with the outer tube 11. Furthermore, a sleeve 24 is provided at the end of the outer tube facing the front mounting, and the upper housing 16, the holding element 9, the outer tube 11, the sleeve 24 and the motor holder 28 serve to enclose the individual components in the linear actuator.

A rigid stopper 13 for restricting the linear movement of the spindle nut 10 is fitted to the right end (outer free end) of the spindle 23, and a washer 14 for slidably supporting the inner periphery of the inner pipe 12 is fitted to the outer periphery of the stopper 13.

Preferably, the gasket 14 is made of Polyoxymethylene (POM).

Referring to fig. 2 and 3, a coupling member 4 (the spindle on the rear side of the worm wheel 7 is omitted in fig. 2 for clarity) is fixedly mounted on the unthreaded end of the spindle 23 on the rear side of the worm wheel 7, and rotates integrally with the spindle 23. The coupling member 4 is formed in a stepped shape, i.e., divided into two portions different in diameter, the bearing 3 is mounted on a small diameter portion 4 "(a portion closest to the rear mount 1) of the stepped shape, and the stopper member 6 is mounted on a large diameter portion 4' (a portion closest to the worm wheel 7) of the stepped shape; wherein the braking member 6 is preferably a coil spring. The wrap spring applies a torque to the spindle 23 opposite to its direction of rotation to decelerate the spindle nut 10 as it moves forward to the end of its travel.

In the embodiment of the present application, in which the rear mounting member 1 is integrally a single component made of a plastic material (e.g., nylon) having a certain hardness, a plurality of cantilever portions 1 ″ having the same shape extend forward on the cylindrical portion 1' of the rear mounting member 1 in the axial direction of the spindle 23. Preferably, the plurality of cantilever portions are arranged at equal angular intervals in the circumferential direction. A radially inwardly extending protrusion 1 "'is formed in the body of each cantilever part near the free end, and a bearing 3 mounted on the coupling 4 is received in a bore defined jointly by the body of the plurality of cantilever parts, the radially inwardly extending protrusion 1"' and the cylindrical part of the rear mounting member 1.

As shown in fig. 2, a spacer 2 functioning as a stopper is arranged on the spindle and on the rear side (left side in fig. 1) of the bearing 3 in the axial direction of the linear actuator. Which prevents the bearing from moving backwards along the spindle 23, while the front side of the bearing 3 is limited by the side of the large diameter part 4' of the two different diameter parts of the coupling 4, thereby preventing it from moving forwards or shifting relative to the spindle 23.

In some embodiments, the plurality of protrusions extending radially inward also serve to limit the forward movement of the bearing 3 to some extent.

As shown in fig. 2 and 3, the rear mounting member 1 preferably includes four cantilever portions, but the present application is not limited thereto, and the number of the cantilever portions may be 2, 3 or even more than four. The cantilever part 1 "extends from the integral cylindrical part 1' of the rear mounting member 1. The cantilever parts are made of a resilient material having a certain stiffness, wherein a radially inwardly protruding protrusion is formed at the free end of each cantilever part 1 ", which protrusion is perpendicular to the inner surface of the cantilever part 1" on the side to be in abutment with the bearing 3. When the bearing 3 is mounted, each cantilever part 1 "is pushed by the bearing 3 to bend and expand radially outwards, said cantilever part 1" regains its original shape by virtue of the elastic properties of its material after the bearing 3 is in place against said protrusion, thereby holding the bearing 3 in place. Thereby ensuring the cylindricity and concentricity of the containing cavity formed by the cantilever part 1' and the cylindrical part 1

The braking member 6 is preferably a coil spring, but the present application is not limited thereto. The wrap spring is mounted on the large diameter portion 4 'of the coupling portion 4 between the radially inwardly extending projection 1' "on said cantilever portion 1" and the worm wheel 7, and one end 6 'of the wrap spring is fixed to the large diameter portion 4' by welding, soldering or other means, while the other end 6 "thereof projects radially outwardly (as shown in fig. 4) and is fixed in the following manner, see fig. 3-5: a fixed matched brake piece holding part 5 is clamped between two adjacent cantilever parts in the plurality of cantilever parts 1', one side of the brake piece holding part 5 and the corresponding side of the adjacent cantilever part form a clamping part 25, and the clamping part 25 is preferably formed by corresponding clamping grooves on the two. The other end 6 "of the wrap spring is held in the catch 25. However, the catch portion 25 in the present application is not limited to the form of a card slot.

In fig. 4 and 5, the brake holding portion 5 is shown mounted on two adjacent cantilever portions to hold the radially outwardly projecting end of the wrap spring in place.

Preferably, a safety nut 22 is disposed around the spindle 23 at the rear side of the spindle nut 10 along the axial direction of the spindle, and when the spindle nut 10 is worn due to malfunction or for long-term use or slips due to an excessive load, the safety nut 22 performs an ejector function on the spindle nut 10, so that the spindle nut can be safely operated, thereby extending the operating life of the linear actuator and ensuring the safety of the operation of the linear actuator.

It is further preferred that a cavity is provided between the large diameter part of said spindle nut 10 and the spindle 23, said safety nut 22 being arranged in the cavity and being held by said spindle nut 10 on the spindle 23 for rotation with the spindle nut 10 on the spindle 23, see in particular fig. 2.

In a specific embodiment, the motor 17 is connected to the housing of the linear actuator by motor connection bolts 18, 19.

In a specific embodiment, an auxiliary bearing 8 is provided on the radially outer portion of the base portion of the worm wheel 7 mounted on the spindle 23. The auxiliary bearing 8 is pressed between the base part of the worm wheel 7 and said upper housing 16, thereby keeping the spindle straight during operation of the linear actuator.

Adjacent to the base of the worm wheel 7 there is provided a magnet 20 supported by a clamp 21, which magnet 20 is associated with an electronic control device of the linear actuator, such as a printed circuit board (PCB board), not shown in the figures, which calculates the number of rotations of the spindle in response to the induction of the rotation of the spindle by the magnet 20, thereby controlling the amount of movement of the spindle nut 10 along the spindle 23. The magnet 20 is fixed by a clamp 21.

Preferably, the bearing 3 and the auxiliary bearing 8 are both ball bearings, but the present application is not limited thereto.

The invention also relates to an adjustable device comprising the linear actuator, wherein the front mounting part and the rear mounting part of the linear actuator are respectively and fixedly mounted on the corresponding mounting parts of the adjustable device for adjusting the size or the inclination of the adjustable device.

The technical solution of the present invention has been described in detail above with reference to the accompanying drawings.

The terms "front," "back," "left," "right," "up," "down," and the like in the description and in the claims, if any, are used for descriptive purposes and not necessarily for describing permanent relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the disclosure described herein are, for example, capable of operation in other orientations than those illustrated or otherwise described herein.

As used herein, the word "substantially" is meant to encompass any minor variations due to design or manufacturing tolerances, environmental influences, and/or other factors.

It will be further understood that the terms "comprises/comprising," "includes" and/or "including," when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Although exemplary embodiments of the present disclosure have been described, it will be understood by those skilled in the art that various changes and modifications can be made to the exemplary embodiments of the present disclosure without substantially departing from the spirit and scope of the present disclosure. Accordingly, all changes and modifications are intended to be included within the scope of the present disclosure as defined in the appended claims. The disclosure is defined by the following claims, with equivalents of the claims to be included therein.

Claims

1. A linear actuator, characterized in that, the linear actuator comprises:

upper shell;

a mandrel arranged between the front mounting part and the rear mounting part, a worm wheel is fixedly mounted on the mandrel, and an external thread is formed on the outer surface of the mandrel between the worm gear and the front mounting part;

a motor and a transmission mechanism, the transmission mechanism comprising a worm gear engaged with the worm gear, the motor being arranged in a motor holder connected to the upper housing;

a mandrel nut arranged on the mandrel, the inner thread of the mandrel nut is engaged with the outer thread of the mandrel;

an inner tube, one end of which is attached to the mandrel nut and the other end of which is attached to the front mount, the inner tube being disposed parallel to the mandrel at a distance around the mandrel;

an outer pipe member arranged in parallel with the inner pipe member at a certain distance around the inner pipe member;

wherein the rear mount is a one-piece piece comprising a cylindrical rear section and including a plurality of identical pieces extending parallel to the front in the axial direction of the mandrel from the cylindrical rear section The forward section of the cantilever portion, the free end of each cantilever portion having a radially inwardly extending projection, the bearing on the rear end of the mandrel is retained in the front and rear sections defined by the front and rear sections. into the cavity to abut the protrusion.

2 . The linear actuator of claim 1 , wherein the plurality of identical cantilevered portions are formed on the circumference of the cylindrical rear section at equal angular intervals. 3 .

3. The linear actuator of claim 1, wherein the plurality of identical cantilever portions are made of a plastic material having a certain hardness.

4 . The linear actuator according to claim 1 , wherein an auxiliary bearing is provided on the base portion of the worm gear that is fixedly mounted on the spindle, and the auxiliary bearing is pressed against the between the base portion of the worm gear and the upper housing of the linear actuator.

5 . The linear actuator of claim 2 , wherein the number of the plurality of identical cantilever portions is more than two. 6 .

6 . The linear actuator according to claim 1 , wherein a cavity is formed between the rear part of the spindle nut and the spindle, and a thread is provided in the cavity to be threaded with the spindle. 7 . An engaged jam nut retained on the mandrel by the rear of the mandrel nut.

7 . The linear actuator according to claim 1 , wherein a coupling member in a stepped configuration is fixedly mounted on the rear end portion of the spindle, and the bearing is mounted on a small diameter portion of the stepped configuration. 8 . On the large diameter portion of the stepped configuration, a coil spring is mounted.

8 . The linear actuator according to claim 7 , wherein a stopper holding part is provided between two adjacent cantilever parts of the plurality of identical cantilever parts, the stopper holding part being connected to The holding portion formed by one of the two adjacent cantilever portions fixes one end of the coil spring extending outward, and the other end of the coil spring is fixed on the coupling member.

9 . The linear actuator according to claim 8 , wherein the retaining portion corresponds to one of the two adjacent cantilever portions by a retaining slot on the retaining portion of the braking member. 10 . The card slots are formed by both.

10 . The linear actuator according to claim 1 , wherein a gasket for slidingly supporting the inner pipe is provided between the stopper and the inner pipe, and the gasket is polyoxymethylene. 11 . washer.

11. The linear actuator of claim 1, wherein the mandrel nut cooperates with a linear guide track on the outer tubular member to allow the mandrel nut to move back and forth.

12. The linear actuator of claim 1, wherein the front end of the mandrel is supported in the inner tube by a rigid stop.

13. An adjustable device, characterized in that the adjustable device comprises the linear actuator according to any one of claims 1-12, wherein the front mount and the rear mount of the linear actuator are respectively mounted on on the corresponding mounting part of the adjustable device to adjust the size or inclination of the adjustable device.

14. The adjustable device of claim 13, wherein the adjustable device is a rehabilitation bed or surgical bed or furniture type device.