Linear actuator with anti-rotation mechanism

Abstract

A linear actuator includes elongate first and second belts that cooperate to form an extendable and retractable column. Rotatable first and second belt guide members respectively guide turns of the first and second belts into interwound engagement. A power actuator causes rotation of the first and second belt guide members such that the extendable and retractable column can be extended or retracted. A base carries the power actuator, the first and second belts, and the first and second belt guide members. An anti-rotation mechanism includes a first anti-rotation member attached to the base and a complementary second anti-rotation member attached to at least one of the first and second belts, wherein the first and second anti-rotation members engage one another in the column to prevent rotation of the column relative to the base. The engagement of the first and second anti-rotation members around the perimeter of the column is non-point-like.

Description

[0001] Cross-reference data

[0002] This application claims conventional priority to U.S. Provisional Patent Application No. 63 / 136,310. Technical Field

[0003] The present invention relates to linear actuators of the type that use intertwined tapes to form lead-out posts, and more particularly, to anti-rotation mechanisms for such linear actuators. Background Technology

[0004] Machines used for moving loads include linear actuators that use a flat, spiral-shaped band to form a vertically extendable and retractable column at one end of which the load is engaged. This type of device is primarily, but not exclusively, used for raising and lowering loads.

[0005] One known linear actuator of this construction comprises a hollow, generally cylindrical rotor rotatably supported on a base fixed to the ground. A motor selectively actuates the rotor. A first horizontal belt is vertically stacked in a helical (or three-dimensional helix) configuration and rests in a first belt reservoir, while a second vertical belt is horizontally stacked in a planar helix configuration in a second belt reservoir positioned coaxially around the rotor. The lower end of each belt is always located in its corresponding reservoir, while the upper end of each belt is fixedly attached to a support platform engaged below the load to be lifted. As the rotor rotates, each turn of the vertical belt is guided and mounted in a helical configuration between two consecutive vertical turns of the horizontal belt, gradually forming a vertically extendable column. More specifically, the load supported by the column is transmitted through each consecutive vertical and horizontal belt turn resting against each other, and subsequently to the rotor supporting the horizontal belt, and finally through ball bearings to the base and ground that ultimately supports the load.

[0006] Such a device is improved by providing an interlocking mechanism that interlocks the horizontal and vertical belts. More specifically, the first belt includes teeth, and the second belt includes an opening such that the teeth of the first belt can engage with the opening of the second belt to interlock the first and second belts. This helps prevent accidental disengagement of the continuous loops of the belt forming the post and also allows the linear actuator to be used when its axis is not vertical, for example, when the linear actuator can be set horizontally.

[0007] In either of these two linear actuator configurations, a rotor rotates about a first belt and a second belt, and carries guides to cause the successive turns of the first and second belts to form an interlocking relationship to create a vertical column. The guides carried by the rotor of the linear actuator specifically include: a first guide member, such as a helical groove in the rotor, which guides the turns of the first belt from the first belt reservoir into the vertical column; and a second guide member, such as an insert pad, which slides onto the outer surface of the second belt to guide its turns from the second belt reservoir into the vertical column.

[0008] When the rotor rotates together with the first and second guide members it carries, the vertical column itself does not rotate. If it rotates, the first and second belts will not be actuated to engage with each other, the vertical column will not form, and the load will not be lifted.

[0009] To prevent rotation of the first and second belts forming the vertical columns, it is known to fix the upper ends of the first and second belts to a support platform of a linear actuator, which is then fixed to the lifted load; and simultaneously, to prevent the load from rotating. For example, if the load is a theater stage lifted by a linear actuator, the theater stage can be guided along a vertical track to allow vertical movement but prevent rotation.

[0010] In summary, existing linear actuators with interlocking bands require attachment to a raised load, and the raised load must participate in preventing column rotation.

[0011] A prior art linear actuator provides a solution to avoid the need for a load to prevent rotation of a column. This prior art linear actuator has a ring of spaced anti-rotation rollers mounted to a fixed base of the linear actuator. These rollers cooperate with teeth arranged on a first belt to prevent rotation of the vertical column. The teeth protrude through openings in a second belt to interlock continuous loops of the second belt, and the teeth also protrude beyond the outer wall surface of the lead-out column. When the vertical column is led out or retracted, the teeth in the column slide within a space defined between the anti-rotation rollers as they move up or down. This causes the teeth to tangentially abut against the corresponding rollers while still allowing free vertical movement. Therefore, this anti-rotation mechanism inherent in the lead-out column prevents rotation of the column even if it does not prevent rotation of the load lifted by the linear actuator, or even if the linear actuator is not fixed to the load at its tip, thus allowing the column to be deployed as intended.

[0012] One problem with this system is that the anti-rotation rollers are arranged in a plane perpendicular to the longitudinal axis of the column, and the abutment of the teeth on the anti-rotation rollers is punctual; that is, a single tooth actually abuts against a single roller at a single peripheral location around the perimeter of the column, or very few teeth abut against very few rollers at essentially a single peripheral location around the perimeter of the column. As the column is formed, with each roller subsequently put into use, the position of this punctual abutment of the teeth on the rollers will shift around the vertical column. This is not ideal because the abutment resulting from tangential abutment is not uniformly distributed around the perimeter of the column; it is always essentially punctual. This uneven redistribution of abutment around the vertical column leads to undesirable tangential and radial mechanical stresses on the column. Summary of the Invention

[0013] Therefore, one object of the present invention is to provide an inherent anti-rotation system for linear actuators that improves upon existing systems.

[0014] Therefore, the present invention relates to a linear actuator comprising:

[0015] • The slender first band;

[0016] • A slender, generally flat second band;

[0017] The first and second strips have: corresponding storage portions where the first and second strips are separated from each other; and corresponding post portions where the first and second strips engage with each other to form a pull-out and retractable post, wherein the post portion of the second strip forms a helix about a longitudinal axis;

[0018] • A rotatable first belt guide member that guides the loops of the first belt from its storage portion into its post portion;

[0019] • A rotatable second belt guide member that guides the loops of the second belt from its storage portion into its column portion;

[0020] • A power actuator that causes rotation of the first guide member and the second guide member, such that the extendable and retractable post can be extended or retracted;

[0021] • The base, which carries the power actuator, the first belt and the second belt, and the first belt guide member and the second belt guide member; and

[0022] • An anti-rotation mechanism comprising a first anti-rotation member attached to the base and a complementary second anti-rotation member attached to at least one of the first belt and the second belt, wherein the first anti-rotation member and the second anti-rotation member engage with each other at the post portion of the first belt and the second belt to prevent the extendable and retractable post from rotating relative to the base.

[0023] The engagement of the first anti-rotation member and the second anti-rotation member around the periphery of the extendable and retractable column is non-point-like.

[0024] In one embodiment, the non-point engagement of the first anti-rotation member and the second anti-rotation member includes an engagement of the first anti-rotation member and the second anti-rotation member around at least one full circumference of the extendable and retractable post.

[0025] In one embodiment, the first anti-rotation member and the second anti-rotation member include a first abutting member and a second abutting member that are tangentially abutting each other relative to the extendable and retractable column.

[0026] In one embodiment, the first anti-rotation member and the second anti-rotation member include teeth disposed on the base or on at least one of the first and second belts, and grooves disposed on the other of the base or on the other of the first and second belts, wherein the grooves are parallel to the longitudinal axis such that when the extendable and retractable post is extended or retracted, the teeth can slide relative to each other in a direction parallel to the longitudinal axis, but the extendable and retractable post is prevented from rotating about the longitudinal axis by the teeth abutting against the wall of the groove.

[0027] In one embodiment, the teeth are disposed on one of the first belt and the second belt, and the grooves are disposed on the base.

[0028] In one embodiment, the groove is provided on an anti-rotation ring, the anti-rotation being provided around a portion of the extendable and retractable post.

[0029] In one embodiment, the first belt guide member and the second belt guide member are carried by a rotor operatively coupled to the power actuator to allow the rotor to rotate via the power actuator, the rotor carrying the first belt and the second belt, as well as the first belt guide member and the second belt guide member.

[0030] The present invention also relates to an anti-rotation ring for use with linear actuators of the following type:

[0031] • A long, generally flat strip having a post portion where the loops of the strip engage with each other to form a helix about a longitudinal axis, thereby forming a retractable post designed to extend through the anti-rotation ring. The strip also has a storage portion where the loops of the strip are separated from each other.

[0032] • A rotatable belt guide member that guides the loops of the belt from its storage portion into its column portion;

[0033] • Interlocking components that interlock the loops of the belt located in the column portion;

[0034] • A power actuator that causes rotation of the guide member, such that the extendable and retractable column can be extended or retracted;

[0035] • The base, which carries the power actuator, the belt, and the belt guide member; and

[0036] • Teeth protruding from the retractable and extendable column;

[0037] The anti-rotation ring includes an attachment device for securing the anti-rotation ring to the base, and a groove coaxially disposed on the inner surface of the anti-rotation ring for cooperating with the teeth of the linear actuator to allow the teeth to move in the groove in a direction parallel to the longitudinal axis, but to prevent the lead-out and retractable post from rotating relative to the base about the longitudinal axis, and wherein the engagement of the teeth with the groove about the periphery of the lead-out and retractable post is non-point-like.

[0038] The present invention also relates to a linear actuator comprising:

[0039] • A slender, essentially flat band;

[0040] • The belt has a post portion where the loops of the belt engage with each other to form a helix about a longitudinal axis, thereby forming a retractable post. The belt also has a storage portion where the loops of the belt separate from each other.

[0041] • A rotatable belt guide member that guides the loops of the belt from its storage portion into its column portion;

[0042] • Interlocking components that interlock the rings of the column portion of the belt;

[0043] • A power actuator that causes rotation of the guide member, such that the extendable and retractable column can be extended or retracted;

[0044] • The base, which carries the power actuator, the belt, and the belt guide member; and

[0045] • An anti-rotation mechanism comprising a first anti-rotation member attached to the base and a complementary second anti-rotation member attached to the belt, wherein the first anti-rotation member and the second anti-rotation member engage with each other at the post portion of the belt to prevent the extendable and retractable post from rotating relative to the base;

[0046] The engagement of the first anti-rotation member and the second anti-rotation member around the periphery of the extendable and retractable column is non-point-like. Attached Figure Description

[0047] In the attached diagram:

[0048] Figure 1 This is a front view of a linear actuator equipped with an anti-rotation device according to the present invention;

[0049] Figure 2 and Figure 3 It shows Figure 1 A partial cutaway perspective view of the linear actuator, in which the base, rotor, second belt, and part of the anti-rotation device are cut away to show otherwise internally hidden components, wherein... Figure 2 The vertical column is shown in its first position, which is mostly retracted, and Figure 3 It shows relative to Figure 2 Partially extended vertical columns;

[0050] Figure 4 It is an enlarged top view, a partially sectional perspective view, which shows Figure 1 The housing of the linear actuator, as well as the anti-rotation ring and the attachment plate for attaching the anti-rotation ring to the housing;

[0051] Figure 5 yes Figure 4 Exploded bottom perspective view of the components;

[0052] Figure 6 yes Figure 1 An enlarged, partially cut-away perspective view of the anti-rotation ring of the linear actuator and the several turns forming the first and second bands of the lead-out post; and

[0053] Figure 7 and Figure 8 yes Figure 1 An enlarged, partially cut-out perspective view of the anti-rotation device of the linear actuator and several turns of the first band forming the lead-out post, which sequentially shows the vertical movement of the first band relative to the anti-rotation device. Detailed Implementation

[0054] Figures 1-3 A linear actuator 10 according to the invention is shown for moving a load (not shown) along a longitudinal axis A. In most applications, axis A will be vertical, and the linear actuator 10 will be used to vertically raise and lower the load; however, axis A may also be non-vertical due to the interlocking nature of the band forming the linear actuator 10 as described below. For simplicity, the following description may assume that axis A is vertical, but it should be understood that this should not be considered as a limitation in any way.

[0055] The linear actuator 10 includes a hollow rotor 12 rotatably supported on a base 14, which rests on and is fixed to the ground. The base 14 includes a flat base plate 16 and a central column 18 erected from the base plate 16. High-capacity bearings 20, 22 allow the rotor 12 to be rotatably supported by the central column 18.

[0056] The base 14 includes a housing 32, which is fixed to and stands upright from the substrate 16. More specifically, and as in Figures 4-5 As further seen, the housing 32 includes four spaced sidewalls 32a, 32b, 32c, 32d that support a top wall 32e in which a circular central housing opening 32f is formed. The housing 32 extends spaced above and over the substrate 16 and partially encloses the rotor 12. The housing 32 may have a different construction than that shown in the figure; for example, it may have a continuous peripheral wall instead of spaced sidewalls 32a, 32b, 32c, 32d, or include any other modifications that will be apparent to those skilled in the art.

[0057] The linear actuator 10 includes a power actuator comprising a motor 24 equipped with a control panel 26, which selectively rotates the rotor 12 by means of a pair of interconnecting gears 28, 30 respectively attached to the motor 24 and the rotor 12. The base 14 includes a motor support 31 carried by a housing 32, which in turn carries the motor 24.

[0058] The linear actuator 10 forms a lead-out and retractable post 33 with a first band 34, which is used to interlock the successive turns of the second band 38 and transfer the load from one turn of the second band 38 to the next.

[0059] More specifically, the first belt 34 has a storage portion 34a, which is spirally stacked and stored in a first belt storage compartment 36, which is an annular space formed inside the lower portion 12a of the rotor 12. The first belt storage portion 34a can rest on the bottom wall 12d of the rotor 12 (and slide on it when the rotor 12 rotates), or be suspended above the bottom wall 12d of the rotor 32, as... Figures 2-3As shown in the diagram, the second belt 38 has a storage portion 38a, which is horizontally stacked in a planar spiral shape and stored in a second belt storage compartment 40, which is an annular space formed radially outside the upper annular wall portion 12b of the rotor 12 between the rotor 12 and the housing 32. The second belt storage portion 38a rests on a horizontal support wall portion 12c of the rotor 12 and slides thereon as the rotor 12 rotates. An opening 12e is formed in the upper wall portion 12b of the rotor 12, and the second belt 38 extends through this opening 12e into the radially inward space of the upper wall portion 12b.

[0060] The first belt 34 and the second belt 38 have pillar portions 34b and 38b, which are arranged to form a retractable pillar 33, as detailed below. As the pillar 33 is gradually retracted, the length of each first belt pillar portion 34b and second belt pillar portion 38b changes in a manner inversely proportional to the change in length of its storage portions 34a and 38a.

[0061] The upper ends of each of the straps 34, 38 are securely attached to a load engagement member 42, which engages the load to be moved. If the linear actuator 10 is positioned on the ground such that axis A is vertical (which is typically the case), the load to be moved will be raised or lowered by the linear actuator 10, and thus the load engagement member 42 will support the weight of the load. A platform or other intermediate structure (not shown) may be fixed between the load engagement member 42 and the load.

[0062] The rotor 12 includes a first belt guide member in the form of a helical groove 44 formed in the inner wall portion 46 of the rotor 12. The rotor 12 also includes a second belt guide member in the form of a second belt insert pad 48 carried by the rotor 12. When the motor 24 rotates the rotor 12 in a first direction to draw out the post 33, each turn of the second belt 38 is guided by the second belt insert pad 48 from the second belt storage compartment 40 through the rotor opening 12e and into the post 33, wherein it is arranged in a helical configuration such that the upper edge of each consecutive turn overlaps with the lower edge of the upwardly adjacent turn. Simultaneously, each turn of the first belt 34 is guided from the first belt storage compartment 36 through the helical groove 44 and into the post 33, wherein teeth 50 located on the outer periphery of the first belt 34 engage openings 52, 54 correspondingly located on the overlapping upper and lower edges of the second belt 38 to interlock every two consecutive turns of the post portion 38b of the second belt 38. Therefore, the wall of column 33 is formed by the column portion 38b of the second belt 38, while the teeth 50 of the first belt 34 cooperate with the openings 52, 54 of the second belt 38 as interlocking members to interlock the continuous loops of the column portion 38b of the second belt 38 and to transfer the load between every two continuous loops of the second belt 38. See [reference needed] Figure 6 .

[0063] More specifically, the load displaced by the linear actuator 10 (e.g., supported if axis A is vertical) is sequentially transferred to the load engagement member 42, then through each successive first and second loop of the first belt post portion 34b and the second belt post portion 38b, and subsequently to the rotor 12, on which the first belt 34 rests in the helical groove 44, and finally through the bearings 20, 22 to the base 14 resting on the ground, and finally to the ground on which the substrate 16 is resting.

[0064] Motor 24 can rotate rotor 12 in a second direction opposite to the first direction to retract column 33. Then, the first belt guide member and the second belt guide member (spiral groove 44, insertion pad 48) will guide the turns of the first belt 34 and the second belt 38 to gradually move away from column 33 and enter the first belt storage compartment 36 and the second belt storage compartment 40 respectively.

[0065] The above description represents the standard operation of a linear actuator with a known construction.

[0066] According to the present invention, and as Figures 1-8 As shown, an anti-rotation mechanism is provided to prevent the column 33 from rotating, while the load itself displaced by the column 33 is not involved in preventing the rotation, i.e., the load engagement member 42 is not fixed during rotation.

[0067] The anti-rotation mechanism of the linear actuator 10 includes: a first anti-rotation member 60 attached to the base 14, and more specifically, to the housing 32; and a second anti-rotation member in the form of a protruding end with first teeth 50, which cooperates with the first anti-rotation member as described below.

[0068] The first anti-rotation member 60 includes a ring 62 having an annular shoulder 80 at its lower end for fitting into a circular opening 32f of the housing 32 and resting on its top wall 32e. A recess 82 is formed in the periphery of the lower wall portion 83 of the ring 62 below the shoulder 80, and the recess 82 engages with a protrusion 84 that projects radially inward from the top wall 32e of the housing within the circular opening 32f.

[0069] An annular groove 86 is formed in the lower wall portion 83 of the ring 62 below the shoulder 80. When the ring 62 rests on the top wall 32e using the shoulder 80, the groove 86 is located below the top wall 32e of the housing. A pair of attachment plates 88, 90 engage the groove 86 below the top wall 32e of the housing, such that the top wall 32e of the housing is sandwiched between the annular shoulder 80 and the attachment plates 88, 90. Bolts 92 secure the attachment plates 88, 90 to the top wall 32e of the housing.

[0070] The ring 62 is sized in diameter to tightly receive the post 33 therein. The inner wall 94 of the ring 62 has a plurality of straight grooves 70 parallel to axis A. Each groove 70 has depth and width to receive a tooth 50 or several teeth 50 aligned parallel to axis A therein in a sliding longitudinal engagement, the teeth protruding from the outer edge of the first band 34 beyond the overlapping edge of the second band 38.

[0071] In use, when the post 33 is extended or retracted, the plurality of teeth 50 will each slide and engage with a corresponding one of the grooves 70. More specifically, as... Figure 7 and Figure 8 As shown, the tooth 50 slides within the groove 70 in a direction parallel to axis A, causing the first band 34 to also move in a direction directly parallel to axis A. In effect, when they engage the groove 70 in this way, the tooth 50 tangentially abuts against the sidewall of the groove 70 of the ring 62 to prevent rotation of the post 33. The ring 62 is also prevented from rotating due to its attachment to the housing 32, and specifically, by means of a protrusion 84 engaging within a recess 82. Thus, the tooth 50, in addition to allowing the interlocking engagement of the first band 34 and the second band 38, also acts as a second anti-rotation member, which cooperates with the first anti-rotation member 60 to prevent the post 33 from rotating about axis A.

[0072] In one embodiment (not shown), the first belt may be positioned outside the second belt, and the teeth may project inward. In such an embodiment, the anti-rotation device may be positioned inside the second belt to receive the inwardly projecting teeth in a groove located on its outer surface.

[0073] In another embodiment (not shown), the post may be formed from a single strip, similar to the second strip in the first embodiment, but with one of its upper or lower edges equipped with teeth, while its other edge will be equipped with a corresponding opening. In this embodiment, for example, the interlocking member that interlocks the strip loops in the post portion will include strip teeth that engage the openings of the strip itself. Again, regardless of whether the teeth extend inward or outward from the post, an anti-rotation device with grooves to engage with the teeth can be used to prevent rotation of the post.

[0074] In another embodiment (not shown), anti-rotation pins are provided on any one of the belts, and these anti-rotation pins are different from interlocking teeth. These anti-rotation pins engage an anti-rotation device.

[0075] A linear actuator (not shown) without interlocking teeth between the two belts can also be provided: the two belts will then rest against each other, as is known from prior art devices. In such an embodiment, teeth or pins will be provided on one of the belts solely for anti-rotation purposes, without any interlocking function.

[0076] In all embodiments of the invention, the anti-rotation device and the teeth or pins cooperate to form a non-punctual anti-rotation mechanism. In fact, contrary to the prior art which provides a set of planar annular anti-rotation rollers, where the teeth engage between the rollers at single point locations around the ring, the present invention provides a plurality of teeth that engage non-punctually in grooves of the anti-rotation device.

[0077] In the embodiment shown in the figure, the anti-rotation ring 62 has a longitudinal length sufficient to allow at least one full turn of the first band 34 to engage the groove 70 with the tooth 50, such that the tooth 50 enters the anti-rotation tangentially adjacent to the entire periphery of the post 33 in the groove 70, thereby reducing mechanical stress on the post 33. As shown in the figure, even more than one turn of the tooth 50 can also engage the ring 62.

[0078] Moreover, due to the tight engagement of the post 33 within the ring 62, the longitudinal length of the ring 62 helps the post 33 resist radial forces, including deflection.

Claims

1. A linear actuator, comprising: • The slender first band; • A slender, generally flat second band; The first and second strips have corresponding storage portions, where the first and second strips are separated from each other; And the corresponding column portion, where the first band and the second band join together to form a retractable column, wherein the column portion of the second band forms a helix about the longitudinal axis; • A rotatable first belt guide member that guides the loops of the first belt from its storage portion into its post portion; • A rotatable second belt guide member that guides the loops of the second belt from its storage portion into its column portion; • A power actuator that causes rotation of the first guide member and the second guide member, such that the extendable and retractable post can be extended or retracted; • The base, which carries the power actuator, the first belt and the second belt, as well as the first belt guide member and the second belt guide member; as well as • An anti-rotation mechanism comprising a first anti-rotation member attached to the base and a complementary second anti-rotation member attached to at least one of the first belt and the second belt, wherein the first anti-rotation member and the second anti-rotation member engage with each other at the post portion of the first belt and the second belt to prevent the extendable and retractable post from rotating relative to the base. The first anti-rotation member and the second anti-rotation member are always engaged with each other around the extendable and retractable column at least once.

2. The linear actuator according to claim 1, wherein, The first anti-rotation member and the second anti-rotation member include a first abutting member and a second abutting member that are tangentially abutting each other relative to the extendable and retractable column.

3. The linear actuator according to claim 2, wherein, The first anti-rotation member and the second anti-rotation member include teeth disposed on the base or on at least one of the first belt and the second belt, and grooves disposed on the other of the base or on at least one of the first belt and the second belt, wherein the grooves are parallel to the longitudinal axis, such that when the extendable and retractable post is extended or retracted, the teeth can slide relative to each other in a direction parallel to the longitudinal axis, but the extendable and retractable post is prevented from rotating about the longitudinal axis by the teeth abutting against the wall of the groove.

4. The linear actuator according to claim 3, wherein, The teeth are disposed on one of the first belt and the second belt, and the grooves are disposed on the base.

5. The linear actuator according to claim 4, wherein, The base includes an anti-rotation ring, and the groove is disposed on the anti-rotation ring, the anti-rotation being disposed around a portion of the extendable and retractable post.

6. The linear actuator according to claim 1, wherein, The first belt guide member and the second belt guide member are carried by a rotor, which is operatively coupled to the power actuator to allow the rotor to rotate via the power actuator. The rotor carries the first belt and the second belt, as well as the first belt guide member and the second belt guide member.

7. An anti-rotation ring for use with a linear actuator of the following type: • A long, generally flat strip having a post portion where the loops of the strip engage with each other to form a helix about a longitudinal axis, thereby forming a retractable post designed to extend through the anti-rotation ring. The strip also has a storage portion where the loops of the strip are separated from each other. • A rotatable belt guide member that guides the loops of the belt from its storage portion into its column portion; • Interlocking components that interlock the loops of the belt located in the column portion; • A power actuator that causes rotation of the guide member, such that the extendable and retractable column can be extended or retracted; • The base, which carries the power actuator, the belt, and the belt guide member; as well as • Teeth protruding from the retractable and extendable column; The anti-rotation ring includes an attachment device for securing the anti-rotation ring to the base, and a groove coaxially disposed on the inner surface of the anti-rotation ring for cooperating with the teeth of the linear actuator to allow the teeth to move in the groove in a direction parallel to the longitudinal axis, but to prevent the lead-out and retractable post from rotating relative to the base about the longitudinal axis, and wherein the engagement of the teeth with the groove about the periphery of the lead-out and retractable post is non-point-like.

8. The anti-rotation ring according to claim 7, wherein, The non-point engagement of the teeth and the slots includes at least one full circumference engagement around the extendable and retractable post.

9. A linear actuator, comprising: • A slender, essentially flat band; • The belt has a post portion where the loops of the belt engage with each other to form a helix about a longitudinal axis, thereby forming a retractable post. The belt also has a storage portion where the loops of the belt separate from each other. • A rotatable belt guide member that guides the loops of the belt from its storage portion into its column portion; • Interlocking components that interlock the rings of the column portion of the belt; • A power actuator that causes rotation of the guide member, such that the extendable and retractable column can be extended or retracted; • The base, which carries the power actuator, the belt, and the belt guide member; as well as • An anti-rotation mechanism comprising a first anti-rotation member attached to the base and a complementary second anti-rotation member attached to the belt, wherein the first anti-rotation member and the second anti-rotation member engage with each other at the post portion of the belt to prevent the extendable and retractable post from rotating relative to the base; The first anti-rotation member and the second anti-rotation member are joined to each other around the extendable and retractable column at least once.

Images